JPH0449943B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to electrostatic recording devices such as copying machines, facsimile machines, printers, and the like.

Prior Art Generally, in the electrostatic recording apparatus described above, an electrostatic latent image on a photoreceptor is developed into a visible toner image by toner carried by a developing roller. In this case, in order to obtain a uniform, high-quality toner image, the distance between the photoreceptor and the developing roller, or in the case of a contact development method, the contact pressure between the two must be maintained constant.

However, in an electrostatic recording device in which the developing roller is rotated by gear conduction using a driving gear, when the load on the developing roller increases over time, the developing roller is pushed away from the driving gear to the developing roller. As a result of this force, the distance between the photoreceptor and the developing roller may become abnormally close, or the contact pressure between the two may become abnormally high in the case of a contact development system, resulting in a reduction in image quality.

Purpose In view of the above points, it is an object of the present invention to provide an electrostatic recording device that can perform stable developing work regardless of load fluctuations on the developing roller.

Configuration The present invention achieves the above object in an electrostatic recording device that develops an electrostatic latent image on a photoreceptor by a developing roller rotated by a driving gear, in which the developing roller is separated from the axis of the driving gear. This electrostatic recording device is characterized in that it is provided with a lock plate that controls the device from moving away beyond a predetermined distance.

Hereinafter, the present invention will be explained based on Examples.

FIG. 1 shows the appearance of a laser printer, which is an example of an electrostatic recording device. This laser printer prints characters or the like on a transfer material such as a sheet of paper or an envelope based on instructions from a host computer (not shown). Further, this laser printer can be roughly divided into a printer upper unit 1 and a printer lower unit 2. A paper feed tray 3 is removably attached to the lower unit 2, and a paper discharge switching knob 4 is also provided. The upper unit 1 is provided with an operation panel 5, a font cartridge insertion slot 6, and an emulation card insertion slot 7. Further, the upper surface of the cover 8, which is one of the constituent elements of the upper unit 1, constitutes an upper paper discharge tray 9.

Transfer materials to be printed are stacked and held on a paper feed tray 3. In this example, it is possible to print on a wide variety of transfer materials, from large-sized paper such as so-called legal size to small-sized paper such as envelopes, but when applying transfer materials of such different sizes, it is necessary to Guide plate 254 on tray 3 with arrow K
Guide each size paper by moving it as shown. Both guide plates 254, 254 are linked together on the lower surface of the tray, so that when one moves in either direction in the K direction, the other automatically moves in the other direction in the K direction. The operation panel 5 includes switches and the like for setting the size of the transfer material and various printing conditions. The font cartridge insertion slot 6 is used to insert a font cartridge, that is, a ROM cartridge in which several types of font information are stored, and to send the font information to a character controller, which will be described later. The emulation card insertion slot 7 connects an emulation card (ROM card) to the character controller to match the host computer and this laser printer, depending on the type of host computer (not shown). It is for. The paper discharge switching knob 4 is used to switch whether to discharge the transfer material that has finished printing inside the laser printer to the upper paper discharge tray 9 or to the left outside the laser printer as shown by arrow A. .

Printer upper unit 1 and printer lower unit 2
are hinged together on the back side of the figure, and are fixedly held together on the front side by a locking mechanism that will be described later. If the lock lever knob 10 protruding from the front surface of the cover 8 is pushed up to release the lock mechanism, the upper printer unit 1 can be rotated and lifted from the lower printer unit 2 as shown in FIG. The reason why the upper and lower units 1 and 2 are constructed so that they can be separated from each other is to facilitate maintenance work or to facilitate replacement of photoreceptors, developer, etc., which will be described later.

FIG. 3 is a side sectional view of the laser printer in which the upper printer unit 1 and the lower printer unit 2 are connected to each other. Hereinafter, an outline of the operation of the laser printer will be described using this diagram.

A drum-shaped photoreceptor 11 disposed approximately in the center of the lower printer unit 2 is driven and rotated in a clockwise direction and is first subjected to a discharging action by the charging charger 12 . Charge wire 13 of charger 12
are stretched parallel to the photoreceptor 11 as shown in FIG.

The thus charged photoreceptor 11 is then subjected to an image exposure action by the laser exposure device 14. As shown in FIG. 5, the laser exposure device 14 includes a polygon mirror 16 rotated clockwise by a scanner motor 15, and a laser diode (LD).
unit 17 and first cylindrical lens 18
, the first mirror 19 , and the spherical lens 20
and a second mirror 21.

LD unit 17 has a laser diode (LD)
is built in, and this LD emits a laser beam for writing an image signal based on an image signal, which will be described later. This laser beam is
It enters the spherical lens 20 via the cylindrical lens 18 and the first mirror 19. The laser beam is focused by the spherical lens 20 and refracted upward by approximately 5 degrees, and is incident on one surface of the polygon mirror 16, where it is reflected. Since the light incident on the polygon mirror 16 is refracted upward by the spherical lens 20, the reflected light passes above the incident light. The reflected laser beam is further reflected by the second mirror 21, passes through the second cylindrical lens 22, is guided onto the photoreceptor 11, and is irradiated dot by dot. At this time, as the polygon mirror 16 rotates, the laser beam is scanned on the second mirror 21 and therefore on the photoreceptor 11 as shown by arrow B (main scanning). By this main scanning, a dot line is formed by the laser beam on the photoreceptor. This optical scanning is repeated for each surface of the polygon mirror 16, and at the same time, the photoreceptor 11 rotates in a direction perpendicular to the main scanning direction (sub-scanning direction). A latent image is formed. In this embodiment, main scanning and sub-scanning are performed so that the dot density of this electrostatic latent image is 300 dots/inch. When printing is performed based on such a high-density dot image, it is possible to obtain a clear printed image equivalent to that of the so-called type impact method. Further, in this embodiment, each surface of the polygon mirror 16 is curved to form the second mirror 2.
The scanning image plane on the image plane 1 is made flat. Therefore, the so-called f-θ, which was conventionally disposed between the polygon mirror 16 and the second mirror 21,
No lens is required. As a result, the overall shape of the laser optical device 14 can be significantly reduced in size.

The LD in the LD unit 17 detects a synchronization detection laser beam once for each scan, in addition to the image signal writing laser beam. After this beam is reflected by the polygon mirror 16, it is reflected by the third mirror 2.
3. Enters the optical fiber 25 through the third cylindrical lens 24. The optical fiber 25 is connected to a main controller (described later) that controls the overall operation of the printer, and the image signal writing laser beam is controlled by the synchronization detection laser beam sent to the main controller via the optical fiber 25. Controls the start timing of light emission.

In FIG. 3, the electrostatic latent image formed on the photoreceptor 11 by the laser exposure device 14 is
1 rotation, it is carried to the developing roller 26. In this embodiment, a so-called contact developing method is adopted, and the developing roller 26 is driven and rotated counterclockwise while lightly contacting the photoreceptor 11.
Further, the developing roller 26 is supplied with non-magnetic toner 29 contained in the developing tank 28 by a toner replenishing roller 27 that is disposed at the bottom of the developing tank 28 and rotates counterclockwise. Therefore, the electrostatic latent image on the photoreceptor 11 carried to the developing roller 26 is developed into a visible image by the toner carried by the developing roller 26. In the contact development method in which the photoreceptor 11 and the developing roller 26 are brought into contact, a one-component developer made of non-magnetic toner is used and there is no need to use magnetic toner, so the toner structure is simple. Furthermore, since no carrier is used, the need for carrier replacement when using a conventional so-called two-component developer can be omitted. Furthermore, the non-magnetic toner can easily perform the fixing operation described below, and the fixing device can be manufactured with a simple structure and small size. Furthermore, when a non-magnetic toner is used, the outline of the toner image obtained by development can be clearly defined, and a higher quality image can be obtained than a single-component developer using a magnetic toner.

This toner image is then conveyed to a transfer position, which is a position opposite transfer charger 30. 64 is a toner layer thickness regulating blade, and 65 is a toner cartridge.

While the above process is being executed, the topmost sheet of the transfer material stacked on the paper feed tray 3, for example, the sheet-like transfer paper 31, is transferred to the paper feed roller 32, which is driven to rotate clockwise, and It is separated from other papers by the friction pad 33 that comes into pressure contact with the paper and is sent to the nip portion of upper and lower conveyance rollers 34 and 35, and further conveyed to the photoreceptor 11 by these conveyance rollers.
is transported to the transfer position.

The transfer device transported in this manner is superimposed on the toner image on the photoreceptor 11 at the transfer position, and is subjected to a discharge action by the transfer charger 30.
Due to this discharge, the toner image on the photoreceptor 11 is transferred onto the transfer paper. When the transfer operation is completed, the light from the static elimination lamp 54 consisting of an LED placed next to the transfer charger 30 is irradiated onto the photoreceptor 11 through the transfer paper, and the light from the static elimination lamp 54 is applied to the photoreceptor 11 while overlapping the transfer paper. The surface potential of the photoreceptor passing through the irradiation position is eliminated.

When the potential of the photoreceptor is weakened, the electrostatic adhesion force between it and the transfer paper is weakened, and the transfer paper is attracted to the photoreceptor 11 due to its own weight.
The toner is reliably separated from the toner and sent to a heat fixing device equipped with a heating roller 36 and a pressure roller 37. The transfer paper and the toner image transferred thereon are transferred to the heating roller 3.
While being heated by rollers 6 and 6, pressure is applied from above and below by both rollers 36 and 37, and as a result, the toner image is fused and fixed onto the transfer paper. In order to heat the heating roller 36, a heater 3 is installed inside the heating roller 36.
8 is provided.

The transfer paper that has undergone the fixing operation is separated from the heating roller 36 by a separation claw 39 and sent to a paper discharge roller 40 . A paper ejection switching claw 41 is provided at the downstream position of the paper ejection roller 40, and this switching claw 41 can be switched between the solid line position in FIG. 3 by turning the paper ejection switching knob 4 shown in FIGS. 1 and 2. Switch with the dashed line position.
When the switching claw 41 is at the solid line position, the paper ejection roller 4
The transfer paper that comes out from the transfer paper passes through a conveyance path formed by a paper discharge guide member 42 and paper discharge guide plates 43 and 44, and is discharged to the upper paper discharge tray 9 by an upper paper discharge roller 45. . On the other hand, when the switching claw 41 is at the position shown by the broken line, the transfer paper coming out of the paper ejection roller 40 is ejected out of the printer in a straight line as shown by arrow A.

The manner in which the transfer paper is to be discharged is determined by the operator's operation of the switching knob 4. Generally, printing is performed in page order on weak plain paper transfer paper, and when it is desired to stack the sheets in page order, the sheets are discharged to the upper paper discharge tray 9. On the other hand, when printing on envelopes or other stiff transfer materials, the paper is ejected in a straight line.

Toner that did not contribute to the transfer remains on the photoreceptor 11 after the transfer is completed. This residual toner is neutralized together with the photoreceptor 11 by the static eliminating lamp 54.
It is scraped off from the photoreceptor 11 by the cleaning blade 55. The scraped toner is transferred to the toner collection tank 5 by the toner collection roller 56.
It is sent inside 7 and stored here. The photoreceptor 11 cleaned by the cleaning blade 55 is again subjected to the charging action by the charging charger 12.

The surface of the fixing roller 36 in the embodiment is electrically conductive. In this way, the charge on the transfer paper is removed via the fixing roller during the fixing operation. Conventionally, in order to improve the stackability of the transfer paper, the transfer paper discharged to the outside was charged with a special charge eliminating brush before being discharged, but this embodiment eliminates the need for the charge eliminating brush. Incidentally, in order to impart conductivity to the fixing roller, for example, a method of mixing carbon into a base material such as Teflon can be used. Since carbon has a relatively high hardness, this method can also increase the durability of the roller.

The general operation of the laser printer according to the embodiment has been described above. Details of each part will be explained below.

Image forming section In this embodiment, the photoreceptor 1 in FIG.
1, the charging charger 12, and the toner recovery tank 57 are constructed as one unit (photoreceptor unit 58) as shown in FIG. 4A.
Further, the developing roller 26, toner replenishing roller 27, and developing tank 28 are also connected to one another as shown in FIG. 4b.
It is configured as one unit (developing unit 59). The photoreceptor unit 58 and the developing unit 59 are each detachably supported by an image forming unit case 60.

The photoreceptor unit 58 has a box-shaped case 61, and the support shaft 6 of the photoreceptor 11 is attached to this case 61.
2 is rotatably and detachably supported.
Further, this case 61 is formed with a hole 63 through which the laser beam from the laser optical device 14 (FIG. 3) enters, and furthermore, the case 61 itself accommodates the toner collection tank 57 (FIG. 3). A casing (a wall surrounding the charge wire 13) of the charger 12 is formed.
The cleaning blade 55 and the toner collection roller 56 are each supported by a case 61. The reason why the photoreceptor 11 is made detachable from the case 61 and therefore the toner collection tank 57 is as follows. That is, generally when the toner collection tank 57 becomes full of waste toner, it is replaced with a new one. In this case, the photoreceptor 11 and the toner collection tank 5
If 7 is integrated, the photoreceptor will also be replaced at the same time as the toner collection tank. However,
The lifespan of recent photoreceptors has been significantly extended due to improvements in materials, manufacturing methods, and the like. Therefore, if the photoreceptor is to be used until the end of its life, a very large-capacity toner collection tank is required, making the printer as a whole unnecessarily large. In order to avoid this, the toner collection tank for one photoreceptor can be replaced, thereby reducing the size of the printer and making effective use of the photoreceptor.

The developing unit 59 has a case 66,
This case 66 allows the developing tank 28 (third
A developing roller 26 and a toner replenishing roller 27 are rotatably supported by a case 66. The toner cartridge 65 is removably mounted on the case 66. When the remaining amount of toner in the developing tank 28 becomes low, the cartridge 65 that has been attached until then is replaced with a new cartridge and toner is replenished into the developing tank 28.

The image forming unit case 60 is disposed within the printer lower unit 2. Therefore, the photoreceptor unit 58
The developing unit 59 is also arranged within the printer lower unit 2. When you lift unit 1 on the printer as shown in Figure 2, the photoconductor unit 5
The upper parts of both the developing unit 8 and the developing unit 59 are exposed.

(Attachment of photoreceptor unit 58 and developing unit 59 to image forming unit case 60) As can be seen from FIG. 4, the image forming unit case 60 is formed into a box shape with an open top, and has front and rear walls 60a, 60b. The support shaft 62 of the photoreceptor 11 is shown in FIG.
Groove-shaped support portions 67, 67 are formed to support the. The photoreceptor unit 58, supported on one side by the support portion 67, is pressed against the other side by a stop claw 69. Developing unit 5
9 is also pressed by the stop claw 70 while being housed in the image forming unit case 60. These stop claws 69, 70 are made of a flexible material, and when each unit 58, 59 is inserted into the imaging unit case 60, they expand outward so as not to interfere with the insertion. .

The photoreceptor unit 58 is placed in the image forming unit case 60.
When the photoreceptor 11 is mounted on the housing, a portion of the lower side of the photoreceptor 11 enters an opening 71 formed in the bottom wall of the case 60, and a gear 72 attached to a support shaft further enters a small opening 73.

When the developing unit 59 is viewed from the direction of the arrow, the seventh
As shown in the figure, a gear 74 is attached to the shaft end of the developing roller 26. When the developing unit 59 is attached to the image forming unit case 60,
This gear 74 projects outward from a recess 75 in the rear wall 60b of the imaging unit case in FIG.

FIG. 35 shows a preferred example of the method of mounting the photoreceptor unit to the image forming unit case. In the figure, the photoconductor unit 558 and the image forming unit case 560 have different shapes compared to the photoconductor unit 58 and the image forming unit case 60 shown in FIG. 4, but this is to make the following explanation easier to understand. Photoconductor unit 58 shown in Figure 4
Of course, the mounting method described hereinafter can be applied to the following.

As shown in FIG. 35, a triangular projection 500 is provided on the side surface of the photoreceptor unit 558. This projection can be integrally molded with resin together with the case (corresponding to 61 in FIG. 4a). This protrusion 500 is not provided on one side of the photoreceptor unit 558 as shown in FIG. 36, but is provided on both sides.

The image forming unit case 560 has elongated holes 501, 501 at positions corresponding to the projections 500 when the photoreceptor unit 558 is mounted. The vertical widths of these long holes 501 are large enough to allow a portion of the apex side of the triangular protrusion 500 to fit therein (see FIG. 36).

With the above configuration, the operator can turn the knob 50.
2,502 and photoconductor unit case 558
When installed into the image forming unit case 560, the protrusions 500, 500 first fit into the image forming unit case 56.
Push 0 out to both sides. Image forming unit case 56
0 is made of resin, so it bends outward. Thereafter, when the protrusions 500, 500 reach the elongated holes 501, 501, the image forming unit case 560 elastically restores itself inward, the elongated hole 501 instantly fits into the protrusion 500, and the elongated hole 501 causes the protrusion 500 to is held and fixed. Since the elongated hole 501 is fitted into the protrusion 500 instantaneously and forcefully due to the elasticity of the image forming unit case 560, this fitting is conveyed to the operator as a slight impact feeling (so-called click feeling). This allows the operator to confirm that the photoreceptor unit 558 is securely attached to the image forming unit case 560.

Furthermore, as shown in FIG. 36, when the photoreceptor unit 558 is installed at a predetermined position in the printer lower unit 2, the upper surface of the photoreceptor unit 558 and the bottom surface of the printer upper unit 1 (usually the upper unit frame 47) When V is the gap dimension with the bottom surface) and W is the dimension from the center (apex position) of the protrusion 500 to the top surface of the elongated hole 501 in the attached state, it is preferable to set it so that V<W. . By doing this, even if the photoconductor unit 558 is not completely attached to the image forming unit case 560 (the protrusion 500 and the elongated hole 501 are not fitted), the printer can be removed when the printer upper unit 1 is closed. The top surface of the photoreceptor unit 558 is pressed by the bottom surface of the upper unit 1, and as a result, the photoreceptor unit 558 is automatically attached to the image forming unit case 560 before the printer upper unit 1 is completely closed. It will be done.

(Attachment of the image forming unit case 60 to the printer lower unit 2) A pair of pivot pins 76 and 77 are provided protruding from the left side wall 60d of the image forming unit case 60, and these pivot pins are attached to the printer lower unit 2. Each side plate 78a, 78b of the frame 78 (Figs. 1 and 3)
It fits into the support grooves 79, 79 provided in the. Therefore, as shown by arrow E in FIG.
can be rotated around pivot pins 76, 77 and lifted up while still housed. In this case, as shown in FIG. 3, the lower part of the case 60 serves as the conveyance path for the transfer paper, so when the case 60 is lifted as described above, the paper conveyance path is exposed to the outside, and the paper conveyance path becomes clogged here. transfer paper (so-called jam paper)
can be easily removed. The entire image forming unit case 60 can be removed from the printer lower unit 2 if necessary.

In FIG. 4, a pair of support pins 81, 81 are protruded from the right end of the image forming unit case 60, and a rotating member 82 is rotatably supported by these support pins. This member 82 has a pair of lock claws 83, 8.
3 and a knob 84 are integrally formed. or,
A compression spring 87 is press-fitted between a receiving portion 85 formed by cutting and bending a part of the rotating member 82 and the right end horizontal portion 86 of the image forming unit case 60. is urged toward the image forming unit case 60 around the support pin 81.

A pair of locking holes 88, 88 are formed in the lower frame side plates 78a, 78b, and when the image forming unit case 60 is placed in the device position shown in FIG. They are engaged by the action of spring 87. In this case, as shown in FIG. 3, a compression spring 89 is provided at the lower right end of the image forming unit case 60, and the lower end of this spring 89 is compressed by the lever 90, so that when the case 60 is placed in the mounting position, the 60 is urged counterclockwise by a spring 89 around pivot pins 76 and 77. Therefore, the lock claw 83 comes into pressure contact with the upper surface of the locking hole 88, and the case 60 is reliably locked.

The lever 90 is rotatably supported on the lower frame 78 by a pin 91, and rotatably supports the upper conveyance roller 34 for conveying the transfer paper 31. Image forming unit case 6
0 is installed in the predetermined position shown in FIG. 3, the spring 89 presses the lever 90 as described above. This results in
The upper and lower conveyance rollers 34 and 35 press against each other to convey the transfer paper. The image forming unit case 60 is
When lifted as shown in Figure E, the pressure of the spring 89 against the lever 90 is released, so that if the transfer paper becomes jammed in the upper and lower conveyance rollers 34 and 35, it can be easily removed.

(Relationship with the drive unit) In Fig. 4, the lower frame side plate 78b on the back side
Another frame side plate 78c is fixed to.
A main motor unit 93 having a main motor 92 is attached to the frame side plate 78c. A drive gear 94 is fixed to the output shaft of the main motor 92, and a photoreceptor drive gear 95 and a developing roller drive gear 96 are rotated by this drive gear via an appropriate gear train.

When the image forming unit case 60 is installed in the predetermined position shown in FIG.
a) in the figure meshes with the photoconductor drive gear 95, while the shaft end gear 74 of the developing roller 26 (FIG. 7) meshes with the development roller drive gear 96. When the main motor 92 rotates in this state, the photoconductor 11 and the developing The roller 26 rotates.

(Supporting the developing unit 59) When the image forming unit case 60 is attached, the contact state between the photoreceptor 11 and the developing roller 26 and the meshing state between the developing roller shaft end gear 74 and the developing roller driving gear 96 are shown in FIG. As shown. With the positional relationship as shown in the figure, when the developing roller shaft end gear 74 is driven by the developing roller driving gear 96, the shaft end gear 7 is moved from the developing roller driving gear 96 to the shaft end gear 74.
4. Therefore, the acting force P on the developing roller 26 is in the vertical direction. Since the force of the drive system is thus prevented from acting in the horizontal direction, the pressure force between the developing roller 26 and the photoreceptor 11 is no longer adversely affected by the force of the drive system.

On the other hand, in addition to the gear 74, a lock lever 101 is attached to the shaft of the developing roller 26, as shown in FIG.
It is rotatably mounted on the 4 shaft. A tension spring 102 is attached to the upper part of the lock lever 101, and when the developing unit 59 is not installed in the image forming unit case 60 (FIG. 4), the lock lever 101 is moved by the spring force of the spring 102. It has been lifted and rotated to the upper position.

When the developing unit 59 is placed in the predetermined position shown in FIG. 3 and the printer upper unit 1 is closed, the leaf spring 1 installed in the printer upper unit 1 in advance
03 comes into contact with the lock lever 101 and pushes it down. Then, the recess 10 of the lock lever 101
4 is caught on a lock pin 105 fixedly arranged near the developing roller drive gear 96, as shown in FIG. Movement to is restricted. In addition, pin 10 in Figure 10
6 and the elongated hole 107 are for determining the rotation range of the lock lever 101.

As described above, by limiting the acting force P to the developing roller 26 only in the vertical direction and further regulating the vertical movement of the developing unit 59 with the lock lever 101, the contact pressure between the developing roller 26 and the photoreceptor 11 is stabilized.
Also, the vibration of the developing roller 26 was reduced. When the vibration of the developing roller 26 decreases, the uneven rotation of the photoreceptor 11 decreases accordingly. In this way, jitter in the photoreceptor rotation direction (sub-scanning direction) was significantly reduced. Further, in this case, the rotation of the lock lever 101 by the spring 102 does not impede the operability when attaching and detaching the developing unit 59.

In the case of the above configuration, when the above-described printing process is executed, the developing unit 59 is connected to the leaf spring 10.
It is pressed downward by the spring force of 3. Generally, this configuration alone is sufficient, but in order to more reliably prevent the occurrence of jitter, it is convenient to adopt the following configuration.

A compression spring 108 is provided on the printer upper unit 1 in addition to the leaf spring 103. Printer top unit 1
When the lock lever 101 is closed, the leaf spring 1
03 and the compression spring 108 until it is caught on the lock pin 105. Once the lock lever 101 is locked, the lock pin 105
When the lock lever 101 is caught, a gap is created between the lock lever 101 and the spring 108, and the spring force of the spring 108 no longer applies to the lock lever 101. That is, the lock lever 101 engages with the lock pin 105 only by a small spring force from the leaf spring 103. In this case, when the pressing force by the compression spring 108 is P ₁ and the pressing force by the leaf spring 103 is P ₂ , if P ₁ is too small, the lock lever 101 cannot be rotated sufficiently, and the lock lever 101 cannot be locked. It is easy to cause defects and may cause problems such as gear gaps. Further, if _P2, that is, the pressing force during the printing operation is too large, the contact pressure between the photoreceptor 11 and the developing roller 26 will be adversely affected, and there is a risk of image skipping or jitter. Therefore, when selecting P ₁ and P ₂ , it is necessary to choose the best combination.
In the example, P ₁ =2.0Kg and _P2 =300g.

FIG. 37 shows a preferred example of supporting means for the developing roller 26. In the figure, a lock plate 502 made of a plate material is connected to the developing roller drive gear 9.
6 axis (drive gear shaft 503 and lower frame side plate 78
The position is adjusted and fixed by a pin 504 which is fixed to the position c (FIG. 4). When the developing unit 59 is installed in the image forming unit case 60 (FIG. 4), the shaft 505 of the developing roller 26 fits into the recess 506 of the lock plate 502 either directly or via a bearing (not shown).

As shown in FIG. 38, the lock plate recess 506 has a left inner surface 507 (the surface far from the drive gear shaft 503) formed in an arc shape (half radius R ₁ ) centered on the axis of the drive gear shaft 503. A gap X is formed between the circumferential surface of the developing roller shaft 505 housed in the recess 506 and the inner surface 507 of the recess. This gap X is approximately 40 mm of the module of gear 96.
It is best to set it to a value of about %.

With the above configuration, the developing roller shaft 505, and thus the developing roller 26, will not be separated from the drive gear shaft 503 by more than the distance X. When printing operations are repeated, the load on the developing roller 26 increases due to toner clogging and the like. Then, a force is applied from the driving gear 96 to the developing roller shaft end gear 74 in a direction in which the shaft end gear 74 moves away from the driving gear 96, and as a result, the developing roller 26 is pressed against the photoreceptor 11. If the developing roller 26 is pressed against the photoreceptor 11 with more pressure than necessary, the image quality will deteriorate.

However, in this embodiment, as described above, the inner surface 507 of the recess of the lock plate 502 limits the displacement of the developing roller 26 toward the photoreceptor 11 to less than the distance X. This prevents the image quality from deteriorating due to excessive pressure.

Frame pin 5 in Figures 37 and 38
Hole 508 in lock plate 502 that fits into 04
It is desirable that the hole be a long hole. Drive gear 96
This is so that when the position of the lock plate 502 is adjusted, the lock plate 502 can move freely accordingly.

An upper inner surface 509 that is continuous with the inner surface 507 of the recessed portion of the lock plate 502 is formed as a circular arc surface (radius R ₂ ) centered on the axes of the pivot pins 76 and 77, and when the developing roller 26 is removed from the lock plate 502. It is desirable that the upper end of the roller shaft 505 escapes so that it does not collide.

In FIG. 3, compression springs 109 and 110 are provided on the inner surface of the right end wall of the image forming unit case 60. Although it looks like there is only one in the diagram, there are two in total, one on the front side and one on the back side. These springs are
As shown in FIG. 4b, the case 66 of the developing unit 59
Both ends of are pressed with spring forces P ₃ and P ₄ respectively. On the other hand, a compression spring 111 is provided in a portion of the upper printer unit 1 corresponding to the non-driving side of the developing unit 59 (the side where the gear 74 is not provided). This spring 111 prevents the developing unit 5 from closing when the upper printer unit 1 is closed.
9 is pressed downward by a spring force P ₅ on a part of the non-drive side.

In this way, the developing unit 59, and thus the developing roller 26, are pressed horizontally in the direction toward the photoreceptor 11 at two points, and the developing roller 26 is further pressed downward by a part on the non-driving side, so that the photoreceptor 11 The contact pressure between the toner and the developing roller 26 has become even more stable, making it possible to obtain a toner image of uniform density. Note that the values of P ₃ , P ₄ , and P ₅ are selected appropriately depending on the developing unit 59 and other parts to which it is applied. Incidentally, in the example, P ₃ = 700g, P ₄ = 100g,
P ₅ =1000g.

The developing roller shaft end gear 74 shown in FIG. 7 is attached to a bracket 116 in which an oil seal 112, a retainer 113 (press-fitted), a cushion 114, a side seal 115, etc. are housed, as shown in FIG.
It is attached to the developing roller 26 via. The developer roller 26 rotates during the printing process. If no precautions are taken, toner may spill from between the bracket 116 and the developing roller 26. Therefore, in this embodiment, one end 118 (shaded area) of a seal 117 made of a thin material such as polyethylene film is fixed to the bracket 116, and the seal 117 is rotated while covering the joint between the bracket 116 and the developing roller 26. , the other end 119 is pulled out above the developing unit 59 as shown in FIG. 7, and is further fixed. For fixation, apply adhesive to the seal in the shaded area Q in advance, and apply it to the case 66 of the developing unit 59.
This is done by gluing the To ensure complete adhesion, a plate 120 is further placed on the adhesive part Q.
117, fold back the tip 119 of the tape 117, carry it to the top of the plate 120, and place the plate 120 in this state on the printer unit 1.
It is best to press with

Radial leakage of toner is thus prevented.
In order to completely prevent leakage of toner in the axial direction, it is preferable to interpose a seal plate 121 between the side seal 115 and the developing roller 26. This seal plate 121 has small protrusions 122a on both the front and back sides.
122b are provided in a protruding manner, and these small protrusions further improve the sealing performance of the side seal 115.

In the embodiment, the casing of the charging charger 12 is integrally molded with the photoreceptor unit 58 from resin. This has the advantage of reducing the number of parts and manufacturing man-hours.

By the way, the resin used here is generally an insulating material. When the charge wire 13 is covered only with such an insulating material, the charge wire 13
The voltage at which the discharge starts becomes abnormally high, and as a result, there is an inconvenience that current leaks in an unspecified direction, so-called leakage, before normal discharge to the photoreceptor 11 occurs. Further, even after the discharge to the photoreceptor 11 has started, the discharge becomes unstable. In conventional chargers, the above-mentioned disadvantages were avoided by making the casing surrounding the charge wire from a grounded conductive material, but in this example, the casing was made by integral resin molding, so there were some problems. Compensation is necessary.

Therefore, as shown in FIGS. 3 and 4a, an opening 296 is provided in the upper part of the casing of the charging charger 12.
Open the ground plate 2 made of a conductive material on the bottom of the printer upper unit 1 in the area corresponding to the opening.
97 is provided. In this way, the ground plate 297 functions similarly to the conductive casing in the conventional device, and therefore the above-mentioned disadvantages such as leakage or unstable discharge do not occur.

As shown in FIG. 2, the ground plate 297 has a protrusion 297a on its front side (the side where the operation panel 5 is located).
is formed. This protrusion 297a is connected to an opening 298 provided in the photoreceptor unit 58 when the upper printer unit 1 and the lower printer unit 2 are combined.
Get stuck in. A conductive wire 299 connected to the shaft of the photoreceptor 11 is disposed in the opening 298 as shown by the broken line in FIG.
The earth plate protrusion 297a that penetrates into the conductive plate 2
It is electrically connected to the shaft of the photoreceptor 11 via 99. Generally, the shaft of the photoreceptor 11 is grounded, so the ground plate 297 is also grounded.

Drive System It has already been explained with reference to FIG. 4 that the photoreceptor 11 and the developing roller 26 are driven by the main motor 92. However, in this embodiment, only those two are driven by the main motor 92.
It is not limited to one member.

FIG. 18 shows the gear train driven by the main motor 92 in detail. Photoreceptor drive gear 9
5 and the developing roller driving gear 96, a conveying roller driving gear 97, a paper feeding roller driving gear 98, a heating roller driving gear 99, a paper ejection roller driving gear 100, etc. are also driven. Conveyance roller drive gear 97
drives the lower conveyance roller 35 in FIG. Paper feed roller drive gear 98 drives paper feed roller 32 .
The heating roller drive gear 99 drives the heating roller 36. A paper discharge roller driving gear 100 drives upper and lower paper discharge rollers 40 and 45.

The main motor unit 93 includes a main motor driver 139 in addition to the main motor 92 described above. The main motor 92 includes a crystal oscillator that generates a reference signal for constant speed control, an encoder that indicates the actual motor speed that also serves as a control amount for constant speed control, a power circuit, and a servo circuit that performs constant speed control. It becomes necessary. The main motor driver 139 has the above-mentioned devices mounted on a board, and is fixedly attached to the main motor 92 and integrated therewith. The reason why such an integrated structure is adopted is to minimize the number of cables connecting the above-mentioned devices and the main motor 92, thereby achieving compactness.

Ozone discharge device, cooling device Generally, ozone is generated by the discharge of the electrical charger 12 or the like. If this ozone accumulates at a specific location near the photoreceptor 11 inside the printer, it will cause deterioration of the photoreceptor, which is not desirable. Also, unit 1 on the printer
causes discomfort to the operator when lifted. In this embodiment, these inconveniences are solved by providing the following ozone discharge device.

In FIG. 3, an ozone blowing fan 46 is disposed above the charging charger 12. As shown in FIG.
From 7a toward the back (perpendicular to the paper in Figure 3)
Fixed. The frame 47 to which the ozone blower fan 46 is fixed has a plurality of air blowing openings 4.
8 is open. When the ozone blower fan 46 rotates, air is axially uniformly sent into the vicinity of the photoreceptor 11 through the individual blower openings 48, as shown in FIG. As a result, ozone near the photoreceptor is blown away, and deterioration of the photoreceptor due to ozone is prevented. The ozone blower fan 46 starts at the latest at the same time as the photoreceptor 11 rotates. This is because the rotation of the photoreceptor 11 and the lighting of the charger 12, which is a source of ozone generation, are generally synchronized.
Further, the timing for stopping the ozone blowing fan 46 is set 8 to 10 seconds after the photoreceptor 11 stops.
When the photoreceptor 11 stops, the discharge from the charger 12 also stops, but at the same time, the ozone fan 46
If it is stopped, the ozone accumulated around the photoreceptor 11 cannot be sufficiently blown away. Therefore, the fan 46 is continuously rotated for 8 to 10 seconds to ensure that the ozone is blown away. In addition, 8
The period of ~10 seconds is for the structure of the example, and if the structure is different, the appropriate time is set accordingly.

In FIG. 3, a suction fan unit 49 is provided to the left of the ozone blower fan 46. As shown in FIG. 15, the suction fan unit 49 has a suction fan 50 and an ozone filter 52 supported by a holder 51 fixed to the casing of the suction fan 50. When the suction fan 50 rotates, ozone blown off from the photoreceptor 11 by the ozone blowing fan 46 is attracted to the suction fan 50 and discharged to the outside of the machine via the ozone filter 52. In this way, ozone does not accumulate inside the printer, and the ozone filter 52
Because it passes through the air, ozone is not released to the outside.

As shown in FIG. 16, the filter holder 51 is
It is made of a thin metal material, and a holding piece 53 is formed on one side thereof. The filter 52 is formed into a cylindrical shape by winding a corrugated paper tape in a spiral shape and fixing the outermost surface with adhesive tape, and the paper used as the material is impregnated with carbon. The holding piece 53 of the holder 51 can be manually pushed outward as shown by the arrow C, and can elastically return inward as shown by the arrow D from the pushed out state. The filter 52 is attached to the holder 51
When attaching the filter 52 to the holder 51, first push the holding pieces 53 apart to press the filter 52 against the holder 51, and then return the holding pieces 53 in the D direction. As a result, the filter 52
is held and fixed in position by the holding piece 53 and a portion 47b of the frame. Since no special fixing tools are required, the cost is low and attachment/detachment work is easy.

In FIG. 12, a large number of air holes 123 are formed in the paper conveying rib 124 of the lower frame 78 (details will be described later). Further, in FIG. 13, a large number of air holes 125 are also formed in the lower part of the paper discharge guide member 42 (details will be described later). Therefore, when the suction fan 50 rotates, outside air flows through these holes 123 and 125 toward the fixing device such as the fixing roller 36 and the toner recovery tank 57, and is then discharged from the suction fan 50 to the outside. Therefore, the fixing device and tank 57 are efficiently cooled. The purpose of cooling the fixing device is to prevent the fixing device itself and other devices around it from overheating. The purpose of cooling the toner recovery tank 57 is to prevent the waste toner in the tank 57 from melting and sticking due to heat.

In order to improve cooling efficiency, it is desirable to provide an appropriate space between the image forming unit case 60 and the fixing device in FIG. 3. Cooling is performed efficiently by the air flowing through this space. Suction fan 50
Unlike the ozone blower fan 46, it is constantly rotated because it also serves to cool the fixing device and the like.

Printer case and paper transport system Each component of the printer is surrounded by a cover 8 and a lower frame 78. All of these are integrally molded from a synthetic resin containing 10 to 20% glass fiber, such as Noryl (trade name). In particular, as shown in FIG. 12, the lower frame 78 forms a transfer paper conveyance path (see FIG. 3) and has a large number of ribs 124 arranged along the paper conveyance direction.
have. These ribs are also made by integral molding. Further, among these ribs, the one located below the toner recovery tank 57 of the photoreceptor unit 58 is provided with a large number of air holes 123 as described above. Note that the paper discharge guide plate 44 in FIG. 3 is also integrally molded with the lower frame 78.

The paper discharge guide member 42 is fixed to the side surface 47c of the upper unit frame 47 as shown in FIG. This paper ejection guide member 42 is also molded from synthetic resin, and has the aforementioned numerous air holes 125 at the bottom.
is provided.

The paper discharge guide plate 43 shown in FIG. 3 is integrally molded with the upper cover 8.

As shown in FIG. 17, the drive rollers 45a and 40a of the upper paper discharge roller 45 and the lower paper discharge roller 40 are roller shafts that are detachably and rotatably supported on the upper and lower sides of the paper discharge guide member 42, respectively. 12
It is a rubber ring fitted in a predetermined position on 6,127. A gear 128 is fixed to the shaft end of the lower roller shaft 127, and this gear meshes with the paper discharge roller drive gear 100 (see FIG. 18). This drive gear 100 is supported by an arm 129 rotatably attached to a lower roller shaft 127, and a compression spring 130 is further attached to this arm.

As mentioned above, the paper ejection guide member 42 is attached to the upper unit frame 47 (FIG. 13) of the printer upper unit 1, but when the printer upper unit 1 is closed with the paper ejection guide member 42 attached, the paper ejection roller Drive gear 100 meshes with heated roller drive gear 99 of FIG. At this time, spring 1
30 is compressed by a predetermined amount, and a pressure necessary for transmitting driving force is applied between gears 100 and 99. Thus, when the main motor 92 rotates, the lower roller shaft 12
7 rotates, and the drive sheet discharge roller 40a rotates.
The lower roller shaft 127 and the upper roller shaft 126 are
They are driven and connected by pulleys 131, 131 and a belt 132 stretched around them, so that when the lower drive roller 40a rotates, the upper drive roller 45a also rotates at the same time.

The paper discharge drive rollers 40a and 45a are in pressure contact with driven rollers 40b and 45b, respectively, as shown in FIG. In this embodiment, driven rollers 40b, 45b
As shown in Fig. 19, there is a holder 1 made of spring material.
33 to the lower frame 78 or the cover 8. When the driving rollers 40a, 45a are pressed against the driven rollers 40b, 45b, the holder 1
The arm 136 of 33 flexes to create a spring force and the necessary pushing force to drive the paper.

A slot 134 is formed in the fixed part of the holder 133, and this slot 134 is connected to the lower frame 7.
8 or by press-fitting the holder 133 into the pin 135 protruding from the cover 8.
etc. is fixed. No fasteners such as screws are required.
Further, the driven rollers 40b and 45b are supported by inserting their support shafts into the curved end portion of the arm 136.

Incidentally, it is preferable that the upper and lower roller shafts 126 and 127 be molded from non-conductive synthetic resin. This is because there is no need for grounding. Also, paper ejection rollers 40a, 45
It is preferable that the shaft portion where the rubber ring (a) is provided has a step with respect to the other shaft portions. This is to prevent the rubber ring from shifting.

In FIG. 17, a paper feed ring 137 is lightly press-fitted approximately in the center of the upper roller shaft 126. This ring has small projections 138 on its outer periphery, as shown in FIG. This small protrusion is
This is to push out the rear end of the transfer paper discharged to the upper paper discharge tray 9 (FIG. 3) to improve the stackability of the next transfer paper discharged.

Paper ejection switching claw 41 (third
2) and the paper discharge switching knob 4 (FIG. 2) are as follows. In FIG. 21, the paper ejection switching claw 4
1 and the paper discharge switching knob 4 are connected by a shaft 140. The cam 14 has two recesses in the middle of this shaft 140 (of course, inside the lower frame 78).
1 is fixed. The concave portion of the cam 141 fits into the convex portion of a locking member 142 fixed to the lower frame 78 and formed of a spring material. In this fitted state, the rotation of the cam 141, that is, the rotation of the switching pawl 41 is restricted.

When the knob 4 is turned in the direction of the arrow F from the state shown in the figure, the locking member 142 is pressed and bent, and the cam 1
When the upper concave portion 41 is brought to the convex portion of the locking member 142, the two are fitted again and fixed in position. The upper recessed portion and lower recessed portion of the cam 141 correspond to the solid line position and the broken line position of the switching pawl 41 in FIG. 3, respectively. Note that the size of the concave portion of the cam 141 (for example, radius of curvature) is preferably smaller than the size of the convex portion of the locking member 142. This is because it is possible to securely fix the position.

Printer upper unit 1 is printer lower unit 2
As mentioned above, the skein can be lifted and rotated. This rotation is performed by rotating the upper unit frame 47 of the upper printer unit 1 about a hinge pin 238 fixed to the lower frame 78 of the lower printer unit 2, as shown in FIG. When lifting the upper unit 1, there are cases where it is not necessary to lift it at such a large angle, such as when removing jam paper or performing simple maintenance work. In consideration of such a case, a stop pin 246 is arranged inside the lower frame 78 on the back side of the hinge pin 238 (on the right side in the figure), and when the bracket 247 of the upper frame 47 hits this stop pin 246, the upper frame is closed. It is convenient if the rotation of 47 is restricted.

Further, the stop pin 246 is made removable from the lower frame 78, and the photoconductor unit 58
When it is necessary to lift up the printer upper unit 1 greatly, such as when replacing the developing unit 59, this stop pin 246 is moved to the lower frame 7.
It is more convenient if the upper frame 47 can be removed from the upper frame 8 and lifted up to a substantially right angle as shown by the chain line.

By adopting such a two-stage rotation structure, convenience for the operator can be achieved.

Upper and Lower Unit Lock Mechanism In FIG. 2, when the printer upper unit 1 is closed from the open position shown in the figure as indicated by arrow G, the printer becomes in the state shown in FIG. 3 and is ready to print.
However, when actually printing, it is necessary to lock the upper and lower units 1 and 2 in this state. The mechanism for this will be explained below.

In FIG. 13, lever support brackets 143, 14 are attached to the front surface 47a of the upper unit frame 47.
3 and lever press plates 144, 144 are provided by integral resin molding. The lever support brackets 143, 143 support support shafts 146, 146 at both ends of the lock lever 145. At this time, spindle 1
The upper sides of 46, 146 are pressed downward by presser plates 144, 144. Since the holding plate 144 is made of resin and has flexibility, when inserting the support shaft 146 into the bracket 143, the holding plate 144 is
The insertion operation is performed while pushing the 44 upwardly. When the support shaft 146 enters the recessed portion of the bracket 143, the presser plate 144 automatically moves downward and holds the entire lock lever 145. In order to facilitate the assembly of the lock lever 145 to the upper unit frame 47, the support shaft 146 may be provided with an axial slot.

At this time, the lock lever 145 is rotatable around the support shaft 146;
Since spring members 147, 147 are preliminarily attached to the upper part of the frame 47 so as to protrude toward the frame 47, the lock lever 145 attached to the front face 47a of the frame is urged to rotate in the direction of arrow H. The spring material 147 may be a leaf spring, or may be integrally molded with the entire lock lever 145 from a resin with spring properties.

Lock pawls 148, 148 are integrally formed at the lower portions of both ends of the lock lever 145, respectively. As shown in FIG.
Hooks 149, 149 are integrally formed at positions corresponding to the lock pawls 148. When the printer upper unit 1 is closed, the spring material 14
7, the lock pawl 148 of the lock lever 145 automatically fits into the hole of the hook 149, and the upper unit 1 is locked, that is, fixed. When lifting the printer upper unit 1, first grasp the lock lever knob 10, and then release it from the spring material 14.
7. Rotate it upward against the spring force. Then,
The lock claw 148 and hook 149 are disengaged,
The unit 1 above the printer can be lifted without any trouble. The lock lever knob 10 projects outward from an opening 248 provided on the front surface of the cover 8.

Conventionally, when making such a locking mechanism, a composite structure was often used in which a knob, pawl, etc. were attached to a metal shaft. In contrast, this embodiment has an integral resin structure, so it is lightweight and easy to manufacture. Also, grounding is not required. stoppa 3
12 is formed integrally with the entire lock lever 145, and protrudes toward the case 47 like the spring member 147. This is to limit the rotation of the lock lever 145 to a certain amount in order to prevent the spring material 147 from sagging due to excessive rotation of the lock lever 145.

Below the support brackets 143, 143, positioning protrusions 150, 150 in the paper transport direction and positioning protrusions 151, 151 in the axial direction of the photoreceptor are integrally molded with the frame 47. Of these protrusions, one set on the right side in FIG. 13 engages with the hook 149 on the right side in FIG. 12, and the manner of engagement is shown in FIG. 22. By engaging each of the protrusions with one hook 149, it is possible to ensure that the upper unit frame 47 is not displaced in the photoconductor axial direction (laser main scanning direction) and paper conveyance direction (laser sub-scanning direction). It can be prevented.

Laser Optical Device The general operation of the laser optical device 14 (FIG. 3) has been explained using an example in FIGS. 5 and 6. In this example, the first mirror 19 and the third mirror 23 must be fixed perpendicularly to the case 155 in order to maintain the optical path of the laser beam in a normal state.

In this embodiment, as shown in FIG.
Support part 156 integrally molded with 55 (Fig. 5)
and a presser plate 157 made of spring material.
Fix the mirror 19 etc. In this case, the support part 15
Regarding No. 6, the surface 156a against which the first mirror 19 is pressed is precisely finished vertically.
The mirror 19 is pressed against this vertical surface 156a, and the arms 157a, 15 of the presser plate 157 are
7a presses the mirror 19 against the vertical surface 156a. The arm 157a of the holding plate 157 is configured to press the mirror 19 by bending and deforming when the holding plate 157 is screwed into a predetermined position of the case 155 through the hole 158. At this time, the arm 157a is provided in advance with small protrusions 159, 159 that protrude in the direction of the mirror 19, so that the mirror 19 is pressed at two points via these small protrusions. By this two-point pressing, the mirror 19 is reliably positioned by the vertical surface 156a.

The second cylindrical lens 22, which is briefly shown in FIGS. 3 and 6, has a 13th overall shape.
It is located as shown in the bottom position of the figure. this is,
The entire body, together with the lens part, is made by integral resin molding. This cylindrical lens 22 has an opening 2 provided on the front surface 47a of the upper unit frame 47.
49 to the upper unit frame 4 shown in FIG.
7 can be inserted into a predetermined position and can be pulled out from there. The cylindrical lens 22 inserted at a predetermined position acts as an optical lens, and
It also acts as a sealing member to prevent toner and other debris from entering the optical device 14. Therefore, it is desirable that the fitting between the cylindrical lens 22 and the corresponding portion of the upper unit frame 47 be as airtight as possible.

An example of a means for attaching the second cylindrical lens 22 is as follows. As shown in FIG.
It is arranged inside two side walls 304, 304. A second cylindrical lens 2 is provided on both sides of each side wall 304 integrally formed with the upper unit frame 47.
upper and lower support parts 305 and 30 that slidably guide each side edge 22b, 22b in the longitudinal direction of 2;
6 is molded integrally with the upper unit frame 47, and the second cylindrical lens 22 is supported while being sandwiched between these support parts 305, 306.

The upper and lower support portions 305 and 306 of each side wall 304 are arranged in a staggered pattern, but this is to make it easier to cut out the mold when molding the upper unit frame 47. For example, the support portion may be formed in an appropriate form, such as a parallel guide rail shape.

When the second cylindrical lens 22 is set, as shown in FIG.
7, an elastic piece 308 integrally molded on the upper unit frame 47 engages, thereby preventing the second cylindrical lens 22 from coming off. or,
Stopper 309 integrally bridged with both side walls 304
The regulating piece 310 protruding from the second cylindrical lens 22 comes into contact with the second cylindrical lens 22, and prevents the second cylindrical lens 22 from being pushed deeper than the predetermined set position.

When pulling out the second cylindrical lens 22 for cleaning or replacement, it is sufficient to grasp the knob 22a and pull it in the direction of arrow T. In this way, both elastic pieces 308 are elastically expanded by the bulge 311 at the tip of the second cylindrical lens 22,
The second cylindrical lens 22 is pulled out through the opening 249 of the upper unit frame 47.

The knob 22a is the second cylindrical lens 2.
2 is exposed to the outside through the opening 248 of the cover 8, similar to the lock lever knob 10. Since the opening 248 can be shared in this way, the appearance is not impaired and workability is also good.

A beam shutter 258 provided on the right side of the ozone fan 46 in FIG. 3 is rotatable about a pin 259. As shown in Figure 3,
When the lower units 1 and 2 are closed, the beam shutter 258 is pushed up and rotated by the protrusion 250 (FIG. 4a) on the photoreceptor unit 58, and the laser beam irradiation aperture 251 is opened. When the upper printer unit 1 is lifted, the engagement between the protrusion 250 and the beam shutter 258 is released, and the beam shutter rotates to the right to close the laser beam irradiation port 251.

In this embodiment, when the printer unit 1 is lifted up, the power supply to the laser optical device 14 is cut off and the laser beam is not irradiated due to the action of an interlock switch, which will be described later.
In consideration of the malfunction of the interlock switch 4, the beam shutter 258 is provided to ensure safety.

Further, a shielding member 252 made of an elastic material such as rubber or sponge is fixed to a portion of the upper unit frame 47 of the printer unit 1 corresponding to the laser beam irradiation port 251 (see FIG. 2). Up·
When the lower units 1 and 2 are closed, the lower end of the shielding member 252 comes into pressure contact with the upper surface of the developing unit 58 (see FIG. 4a) in the printer lower unit 2, as shown in FIG. As a result, the area around the laser irradiation port 251 is sealed. This prevents intrusion of toner and other dust into the laser optical device 14, leakage of laser light, and intrusion of light from the outside.

Paper feed/discharge section The paper feed tray 3 is removably attached to the printer lower unit 2. As can be seen from FIG. 1, this paper feed tray 3 has an uneven bottom because a portion 153 provided with a pressing lever 152 protrudes downward. Therefore, if the paper feed tray 3 is removed from the lower unit 2 and left unattended, there is a risk that the rear part of the tray 3 will fall downward like a seesaw, and the transfer paper will slide backward. In order to prevent this, it is preferable to provide a protrusion 154 on the rear bottom surface of the protrusion 153 as shown in FIG. This allows the paper feed tray 3 to sit comfortably and eliminates paper slippage.

At the top of the paper feed tray 3 is a manual feed guide plate 255.
is attached, and this manual feed guide plate 25
The transfer material can be manually fed from above 5 (arrow M in Fig. 3). If you load plain paper transfer paper on the paper feed tray 3 and manually feed envelopes from the manual feed guide plate 255, you can print letters and address notes on the envelopes alternately.
You can also do it one by one.

Further, in the printer according to this embodiment, a paper feed unit 266 can be detachably connected to the lower part of the printer lower unit 2, as shown in FIG. A preliminary paper feed tray 267 is provided in the paper feed unit 266.
A plurality of transfer papers 268 are stacked on top. These transfer sheets 268 are fed one by one into the lower printer unit 2 in the direction of arrow N by a feed roller 269 and a conveyance roller 270. The fed transfer paper undergoes the printing process described above in the same way as the transfer paper 31 on the paper feed tray 3.

Whether to feed paper from paper feed tray 3 or from preliminary paper feed tray 267 is determined by
This can be done by providing a selection switch on the operation panel 5 and giving instructions, or by instructions from the host computer.

Furthermore, as can be seen from the figure, the lower paper feed tray 267
From the upper and lower transport rollers 3 in the printer lower unit 2
The paper transport distance to rollers 4 and 35 is longer than the paper transport distance from paper feed tray 3 to these rollers 34 and 35. On the other hand, in order to effectively carry out the printing process, the time required for the transfer paper from both paper feed trays 3 and 267 to reach the upper and lower conveyance rollers 34 and 35 must be equal. Therefore,
The preliminary paper feed roller 269 in this embodiment is adapted to feed out the transfer paper 267 at a faster speed than the paper feed roller 32 in the printer lower unit 2.

After printing is completed, the transfer sheets are discharged to the upper paper discharge tray 9 and stacked. The deeper the upper paper discharge tray 9 is, that is, the higher the height h from the upper paper discharge tray 9 to the upper paper discharge roller 45, the greater the number of transfer sheets that can be stacked. However, if this depth is too deep, the stacked transfer papers will be disturbed and the printer as a whole will become unnecessarily large. Therefore, depending on the depth and therefore the number of transfer paper stacks, there is a limit.

However, in the case of the above-mentioned embodiment using the preliminary paper feed tray 267, it is conceivable that the number of transfer sheets to be stacked on the upper paper discharge tray 9 increases significantly. For this reason, it is convenient to adopt the following configuration.

As shown in FIG. 30, a paper discharge unit 271 is attached to the left side of the upper and lower units 1 and 2 of the printer. This paper ejection unit 271 is connected to the main body case 2.
72, and a cover 274 pivotally supported thereon via a pin 273 so as to be rotatable in the direction of arrow P. Cover 274 is normally held in the vertical position shown in FIG. 30 by a locking device, not shown. The cover 274 and main body case 272 are provided with a plurality of ribs 275, 276, 277 arranged at intervals in the direction perpendicular to the plane of the paper in FIG.
8 is formed. The main body case 272 supports transport rollers 279 and 280 and a discharge roller 281, and the transfer paper is transported and discharged by each of these rollers.

When conveying the transfer paper through the paper discharge unit 271, the paper discharge switching claw 41 is switched to the position shown by the broken line. As a result, the transfer paper sent out from the paper ejection roller 40 is transferred to the paper ejection unit 27 via the conveyance roller 279.
Sent to 1.

The height H from the paper ejection tray 9 to the paper ejection roller 281 of the paper ejection unit 272 is higher than the height h from the upper paper ejection roller 45 (H>h). Therefore, when transfer sheets are discharged from the paper discharge unit 271, it is possible to stack more transfer sheets. In this case, as a paper ejection method, the upper paper ejection roller 45 of the printer upper unit 1 is initially used to eject the paper, and the transfer paper is ejected from the upper paper ejection roller 45 of the printer upper unit 1.
When the sheets are stacked to a height of , the sheet ejecting roller 281 of the sheet ejecting unit 271 starts ejecting the sheets. In this way, the situation where the transfer paper discharged from the paper discharge unit 271 falls to a deep position can be avoided, and irregularities will not occur in the stacked transfer paper.

In some cases, only the paper ejection roller 281 of the paper ejection unit 271 or only the upper paper ejection roller 45 of the upper printer unit 1 may be used.
Further, these paper ejection rollers 281 and 45 can also be used alternately.

The printer upper unit 1 of the embodiment is lifted and rotated relative to the printer lower unit 2. However, if the upper part of the paper ejecting unit 271 is located above the upper printer unit 1 as shown in FIG. 30, the upper printer unit 1 cannot be lifted up because the paper ejecting unit 271 becomes an obstacle. Therefore, in the illustrated example, the paper ejection unit 271 is supported by the paper feed unit 266 (which may be the printer lower unit 2) via a pin 282 so as to be rotatable in the direction of the arrow Q. When opening and closing the printer upper unit 1, the paper discharge unit 271 is rotated in the Q direction relative to the upper and lower units 1 and 2, and is retracted to a position where it does not interfere with the opening and closing of the printer upper unit 1. Note that the paper ejecting unit 271 may be configured to be detachable from the paper feeding unit 266 or the like, so that it can be removed when the upper printer unit 1 is opened or closed.

When the transfer paper jams in the paper discharge path 278 of the paper discharge unit 271, the cover 274 is rotated in the P direction about the pin 273 and moved to the position shown in FIG. 31. As a result, the paper discharge path 278 is exposed to the outside, so that the jammed paper can be easily removed.

A preliminary switching pawl 283 is provided at a downstream position of the lower conveyance roller 279. This switching pawl 283 is switched between the position shown in FIG. 30 and the position shown in FIG. 31. When the preliminary switching claw 283 is in the position shown in FIG. 30, the paper is ejected to the upper paper ejection tray 9 described above. On the other hand, when the preliminary switching claw 283 is in the position shown in FIG.
and is discharged onto the cover 274. This paper ejection mode is adopted when it is not desired to eject the transfer paper in reverse. Since the cover 274 itself can also be used as a paper discharge tray, the number of parts can be reduced.

In addition, the preliminary switching claw 2 is activated in conjunction with the opening and closing of the cover 274.
It is advantageous to configure the device so that 83 switching operations can be performed because the operation becomes simple. For example, cover 27
A switch (not shown) is provided that turns on and off when the cover 274 is opened and closed, and when the cover 274 is opened to the position shown in FIG. 31, this switch is turned on.
As a result, a drive device (not shown) such as a motor or solenoid is operated to move the preliminary switching pawl 283 to the 30th position.
When the cover 274 is operated from the position shown in the figure to the position shown in FIG. 31, and the cover 274 is closed, the preliminary switching pawl 283 is returned to the position shown in FIG. 1 by the operation of the drive device.

There is also the following method. Figure 30 and 3
As shown in FIG. 1, a cam member 284 is attached to the cover 274.
is fixed, and when the cover 274 is closed, the preliminary switching pawl 283 is moved to the third position by the action of the toggle spring 285.
Hold it in the position shown in Figure 0. When opening the cover 274,
The cam member 284 integrated with this is the preliminary switching pawl 283.
Then apply pressure to it and rotate it to the position shown in Figure 31. The preliminary switching pawl 283 is held in this state by a toggle spring 285.

The paper ejection roller 281 of the paper ejection unit 271 is connected to the upper and lower printer units 1 and 2 as shown in FIG.
It can be configured in the same manner as the paper ejection rollers 40 and 45 inside. Moreover, it is even more convenient to do as shown in FIG. In the figure, the paper discharge roller 281 consists of a drive roller 286 and a driven roller 287, and the drive roller 286 has a driven gear 2 fixed to its support shaft 288.
89 and a drive gear 290 that meshes with the drive gear 290. Connecting member 291 on support shaft 288
is rotatably but non-axially slidably mounted. A nut 29 is attached to the other end of the connecting member 291.
2 is provided, and this nut 292 is engaged with a feed screw 294 that is rotationally driven by a reversible rotor 293.

The position of the transfer paper when discharging the transfer paper to the upper paper ejection tray 9 with the motor 293 stopped is set to the third position.
Assume that the position is indicated by the chain line in Figure 2. After stacking several sheets of transfer paper in this state, the motor 293
to rotate the feed screw 294. Then, the nut 292 moves in the axial direction of the feed screw 294, and the drive roller 286 also moves in the same direction, so that the rollers 286 and 287
The transfer paper sandwiched between is shifted (shifted) by δ as shown by the broken line.

If the transfer paper shifted by δ in this manner is ejected to the upper paper ejection tray 9, it can be distinguished from the transfer paper group that was previously ejected onto the tray 9. In other words, a plurality of transfer papers can be divided into several bundles.

Actually, as shown in FIG. 30, the paper ejection roller 2
A sensor 295 is provided upstream of the transfer paper 81, and when an external signal to shift the transfer paper is input to the main controller (described later), when the sensor 295 detects the trailing edge of the transfer paper, the motor is activated based on the detection signal. 293 to shift the drive roller 286.

Electrical equipment-related In Fig. 24, 160 is a power input section,
It is connected to a commercial power source via an AC plug 161.
This includes a main switch 162 and a nozzle filter 163. The power input section 160 is
As shown in FIG. 12, it is arranged on the back side of the lower frame 78. The main switch 162 is located on the lower frame 7.
It passes through the side wall of 8 and exits to the outside, allowing the operator to perform switching operations from the outside. Noise filter 163 removes external noise from the supplied power.

The power from the power input unit 160 is supplied to a power supply unit for the main controller (main PSU) 165 via an interlock switch 164 on one side, and a power supply unit for the character controller (character PSU) 166 on the other side. Supplied.
The main PSU 165 is placed on the left side of the upper unit frame 47 as shown in FIG. 13, and includes a noise filter 167, a constant voltage circuit 168,
It has a semiconductor relay (SSR) 169. Constant voltage circuit 168 mainly performs AC/DC conversion. SSR
169 is the heater 38 (third
Turns on/off the power supply for temperature control (see figure). As can be seen from FIG. 3, the heater 38 is equipped with a thermistor 235 for temperature control. is arranged at an upper position corresponding to the conveyance path. The reason for this is that envelopes are generally made by gluing, so if the fixing temperature is too high, the glue will melt, causing problems. Therefore, the purpose is to arrange the thermistor 235 closest to the position where the minimum width transfer material such as an envelope will pass, thereby enabling accurate heater temperature control.

The interlock switch 164 is disposed in front of the right side of the lower frame 28 as shown in FIG. 12, and is normally turned off, but turned on when pressed downward. When the printer is assembled, a resin inner cover 170 is attached to the right end of the lower frame 78. As a result, the interlock switch 164 is covered by the switch cover 171 of the inner cover 170. A cross-shaped hole 172 is formed in the switch cover 171. This cross recess is large enough that a human finger cannot fit into it, but a suitably shaped presser 173 (FIG. 2) provided in a corresponding portion of the printer unit 1 can fit therein. Therefore, when the printer upper unit 1 is lifted up as shown in FIG. 2, the interlock switch 164 is off and power is not supplied to the main PSU, but when the upper unit 1 is closed, Interlock switch 164 is turned on and power is supplied. The cross recess 172 is designed so that a person's finger cannot pass through it to prevent the interlock switch 164 from being accidentally turned on when the upper unit 1 is opened. By turning off the interlock switch 164, the laser optical device 1
As described above, when the power supply to 4 is cut off, the laser beam irradiation is interrupted.

The inner cover 170 is attached to the third
As shown in the figure, it covers the paper feed roller 32. This prevents dust and the like from adhering to the paper feed roller 32, and further protects the paper feed roller 32 when the upper unit 1 is lifted.

The character PSU 166 is disposed on the back right side of the upper unit frame 47 in FIG. 13, and a noise filter 174 and a constant voltage circuit 175 are provided inside thereof as shown in FIG. 24.

Main PSU165 is main controller 1
76, power pack for charging charger 12 and developing bias (charging/developing PP) 177, power pack for transfer charger 30 (transfer PP) 178,
It drives the main motor 92, various operating devices 179, etc. It also drives fans such as the ozone fan 46 and the suction fan 50, and the fixing unit heater 38. Character PSU 166 drives character controller 180.

The charging/developing PP 177 is disposed on the back side of the upper unit frame 47 as shown in FIG. On the other hand, the charging charger 12 and the developing roller 26 driven by the charging/developing PP 177 are the third
As already described with reference to FIG. 4, they are arranged in the lower printer unit 2 together with the photoreceptor unit 58 and the developing unit 59, respectively. In order to electrically connect the units disposed across both units 1 and 2, the following configuration is adopted.

First, a terminal 195 is provided on the charging charger 12 as shown in FIG. 4a, and a terminal 196 is provided on the shaft end of the developing roller 26 as shown in FIG. Then, the charging/developing PP 177 is connected from the bottom of the printer upper unit 1 (that is, the bottom of the upper unit frame 47) so as to correspond to these terminals.
The power supply terminals 197 and 198 protrude (FIG. 2). The power terminals 197, 198 have a circular recess 200 with a claw portion 199 as shown in FIG.
The spring terminal 201 is housed in the recess in a state where a preload is generated in advance. Terminals 195, 196 of the electrostatic charger etc. enter into the spring from the lower end of the spring terminal 201 when both the upper and lower units 1, 2 are closed, and the terminals 195, 196 enter the spring from the lower end of the spring terminal 201, and the terminals 195, 196 are wrapped around the terminals 195,196. are connected, and high voltage is applied to the terminals 195 and 196.
Since the spring terminal 201 has a shape that widens toward the lower end, the terminals 195 and 196 can enter without fail. Further, the contact between the spring terminals 195 and 196 is also good. Furthermore, the spring terminal 201 is connected to the claw portion 1
Since it is in a preloaded state by 99, there is no contact failure.

As shown in FIG.
It is fixed on the right side of the transfer charger 30 in the figure. The high voltage terminal from the transferred PP is configured as a spring terminal 202 as shown in FIG. Apply high voltage. The casing 206 of the transfer charger 30 is
Grounding is provided by an integral spring terminal 207 having two spring portions 207a and 207b.

As is clear from FIG. 3, an image forming unit case 60 is placed above the transfer charger 30. As shown in FIG. 26, spacer members 208, 208 are provided at both ends of the transfer charger 30, and the transfer charger 30 connects the spring terminals 202 and 207 via these spacer members 208.
It is pressed against the image forming unit case 60 from below by a. The spacer member 208 is integrally molded with resin together with the end block 204, and its height can be accurately determined. Therefore, transfer charger 30
The distance between the image forming unit case 60 and the image forming unit case 60 is always maintained reliably by the height of the spacer member 208. This allows constant transfer work to be performed at all times.

The main controller 176 is attached to the electrical chassis 181 in the printer unit 1, as shown in FIGS. 13 and 3, and controls charging, exposure, development, transfer, etc. described in connection with FIG. Controls the entire printer process. The character controller 180 is attached to the electrical chassis 181 like the main controller 176, and is connected to the host computer 182.
Character information sent from (FIG. 24) via the Centronics interface (S) or RS232C (R) is sent to the CPU 184 via the interface 183, where a character signal corresponding to the character information is formed. At this time, as described above, the font is formed in a font corresponding to the content of the font cartridge 185 inserted into the font cartridge insertion opening 6 of FIG. 1.

Information from host computer 182 is typically transmitted to character controller 180 (and possibly main controller 176) via an interface cable. In this example, the 13th
As shown in the figure, a connector 253 is provided on the system controller 180 attached to the electrical chassis 181 in the printer unit 1, and the interface cable is directly connected to the character controller 180 via this connector. Since the interface cable is not routed inside the printer, there is no need to worry about noise entering the information from the host computer and causing printing defects.

The main controller 176 includes a CPU 186, a phase synchronization section 187 composed of a gate array, a display drive section 188, a scanner synchronization detection section 189, a scanner motor driver 190, and a video interface section 191.

The display drive section 188 drives the operation panel 5. In the case of this embodiment, as shown in FIG. Button switch group 193 for issuing various instructions and various displays
A group of LEDs 194 is provided. As shown in FIG. 13, the operation panel 5 is detachably attached to the front surface of the electrical chassis 181 and exposed to the outside through the opening 209 of the cover 8. If the mounting position of the operation panel 5 on the chassis 181 is made variable, and the opening 209 of the cover 8 is opened in another location accordingly, the operation panel 5 can be freely moved and the operation surface can be changed. It can be changed. In this case, it is convenient to cover the separate opening 209 with a cap.

The button switch group 193 includes the following switches.

(Font Selection Switch) As mentioned above, a font cartridge (ROM) storing several types of fonts is inserted into the font cartridge insertion slot 6. The font selection switch is operated to select a desired font from among these.

(Line on/off switch) This is used to turn on/off information transmission from the host computer 182 to the character controller 180. When the line is turned on, information is transmitted. When line-off occurs, information transmission is interrupted. By providing the line-off, it is possible to prevent information from the host computer from being input during test printing of the printer or when replacing a font cartridge, emulation card, etc.

The phase synchronization unit 187 drives the laser diode LD of the laser optical device 14 in synchronization with the printing process executed by the CPU 186. In addition, the optical fiber 2
It receives the synchronization detection laser beam (described above) from 5 and controls the light emission timing of the LD. Furthermore, the phase of the scanner motor 15 is controlled via the scanner motor driver 190.

The video interface unit 191 exchanges image information and control data with the character controller 180, and also transmits a clock signal, which is a reference for control, to the character controller 180.

Inside the main controller 176, two voltage converters 210 and 211 consisting of a three-terminal regulator, a DC/DC converter, etc. are provided.
These voltage converters allow +24V, +12V, +5V,
Each voltage of -12V is created. These voltages control the drive motors, solenoids, laser diodes, polygon motors, etc. of each device.
Each logic circuit is driven. The reason why the control voltage is specially created in the main controller 176 in this way is to perform control using a clean power source with little pulsation. As a result, the laser diode's light emission, the polygon mirror's rotation, and other printing processes are executed without malfunction, and printed products with good print quality can be obtained.

The option interface 300 is used to instruct the start and stop timing of the paper feed roller 269 in the paper feed unit 266 (FIG. 30) when the paper feed unit 266 (FIG. 30) is attached.

Power supply unit is main PSU165 and character
The reason for dividing PSU166 into two is as follows.

By providing an interlock switch 164, when the printer unit 1 is lifted up, the power supply from the power input section 160 is automatically stopped.
In this case, the character controller 180
It would be bad if the memory contents of the CPU 184 were also erased at the same time. Therefore, a separate power supply section for the character controller was provided.

Some printers have the character controller 180 installed externally rather than internally.
In this case, the character PSU 166 is not particularly required, so the character PSU 166 is made separate in advance.

The various operating devices 179 shown in FIG. 24 will be described in detail as follows. Paper feed clutch 21
2 controls the rotation of the paper feed roller 32. Paper transport clutch 213 controls the rotation of lower transport roller 35. The total counter solenoid 214 counts up a total counter 215 (located at the back right of the lower frame 78 in FIG. 12 and visible through the window 216 of the inner cover 170) that displays the number of prints. In this embodiment, the solenoid 214 is programmed to operate and count up by "1" each time the transfer charger is turned on during the printing process by the CPU 186 of the main controller 176. The reason for counting up based on the transfer operation is to ensure that the number of printed products corresponds accurately to the count value on a one-to-one basis. If some step prior to the transfer operation in the printing process is used as a reference, when the transfer paper is removed by a jam or the like midway, the number of printed products and the count value will not correspond one-to-one.

The latching solenoid 217 is assembled in FIG. 15 as a component of the suction fan unit 49 (its operation itself is not directly related to the suction fan 50). The detailed action will be described later.

In FIG. 24, the main controller 176
The registration sensor 21 serves as an input device 218 that sends a process reference signal to the CPU 186 of the
9. Paper discharge sensor 220, toner over sensor 2
21, a paper end sensor 222, a latch sensor 223, and a toner end sensor 224 are provided.

The registration sensor 219 is arranged on the right side of the conveyance rollers 34 and 35 in FIG. The starting timing of the lower conveyance roller 35 is determined based on the timing when the transfer paper passes the registration sensor.

The paper discharge sensor 220 is arranged at a downstream position of the fixing device in FIG.

The toner over-sensor 221 is disposed above the detection filler 225 provided at the top of the toner recovery tank 57 in FIG. 3 (attached to the printer upper unit 1). Waste toner cleaned from the top of the photoreceptor 11 accumulates in the toner collection tank 57, and when the tank is full, the detection filler 225 is lifted upward by the waste toner and is detected by the toner over sensor 221.

The paper end sensor 222 is arranged on the right side of the paper feed roller 32 in FIG. 3, that is, above the tip of the paper feed tray 3. When there is no transfer paper on the tray 3, it is detected.

Latch sensor 223 is located above latching solenoid 217 in FIG. It is turned off when the optical path is blocked by the plunger of the solenoid 217.

The toner end sensor 224 is a micro switch located at the bottom of the upper printer unit 1 so as to be located above the cam mechanism 226 provided at one end of the developing unit 59 as shown in FIG. Figure 2). The cam mechanism 226 includes a cam 228 mounted on the rotating shaft of a toner stirring member 227 (FIG. 2) in the developing tank 28, and
It has a lever 230 that comes into contact with the outer peripheral surface of 28 and swings around a pin 229 . Lever 230 is pressed against cam 228 by spring 231.

In FIG. 3, a toner stirring member 227 stirs the toner in the developing tank 28. As shown in FIG. The cam 228 is made up of two cam plates each having a recess (not shown in detail), and the stirring member 22
When the agitation resistance 7 is large (when there is a sufficient amount of toner), the recesses overlap each other, and the lever 230 that comes into contact with it is always lifted upward, turning on the toner end sensor 224.
When the stirring resistance decreases (when the toner runs out)
One of the cam plates rotates out of alignment, the recesses of both cam plates overlap, and the lever 230 falls into the recess.
The toner end sensor 224 turns off and the toner end is detected.

As is clear from the above explanation, the toner end is
It is detected by turning the microswitch on and off by moving the lever 230 upward. Therefore, the distance between the lever 230 and the actuator of the microswitch must always be maintained constant. Therefore, in this embodiment, as shown in FIG. 7, the toner end sensor 224, which is a micro switch, is mounted on a holder 23 formed by curving a spring material.
2, and this holder 232 is fixed to the printer upper unit 1, and the actuator portion of the microswitch is configured to protrude from the printer upper unit 1 toward the printer lower unit (see Fig. 2). .

When the printer upper unit 1 and lower unit 2 are closed, the projecting piece 233 of the developing unit 59 in FIG.
233 pushes up the projecting pieces 234, 234 on both sides of the microswitch while bending the holder 232 upward. When the upper and lower units 1 and 2 are locked, the protrusions 233 and 234 are fixed in position with an interval equal to the height of the switch protrusion 234 while exerting pressure on each other. In this way, the distance between the lever 230 and the actuator of the microswitch is maintained constant.

Line 236 in FIG. 24 indicates a ground line connected between each electrical device. In this embodiment, the ground board 237 is fixedly installed on the lower frame 78 of the printer lower unit 2, as shown in FIG. However, many of the devices shown in FIG. 24 are installed in the printer unit 1 as described above. Since the upper and lower units 1 and 2 rotate with respect to each other around the hinge pin 238, some ingenuity is required to connect the ground lines of each device in the upper printer unit 1 to the ground board 237 of the lower printer unit 2.

In the embodiment, a rigid conductive metal plate 239 is connected to the grounding board 237, and this metal plate 239 is extended above the lower frame 78.
and a grounding plate 240 of the printer upper unit 1 are electrically connected via a connecting plate 241. The connection plate 241 is formed by bending a thin plate of a conductive and flexible material, such as phosphor bronze. Also, both ends 241 of the connection plate 241
a, 241b are curved as shown,
Electrical connection is achieved by screwing these curved terminals to the ground plate 240 and metal plate 239, respectively, using stepped screws 242.

By using the stepped screws 242, the connection plate 241, the ground plate 240, and the metal plate 239 are not connected by screw force, but are brought into contact by the spring properties of the curved terminal parts 241a and 241b themselves. is ensured. This prevents the contact state of the contact portion from deteriorating over time and permanently provides a good contact state. In addition, since the entire connecting plate 241 is finished in a curved shape, even if the upper and lower units 1 and 2 rotate relative to each other, the connecting plate 241
can freely follow the rotation, and there is no need to place a large burden on the terminal portions 241a, 241b.

When the upper printer unit 1 is lifted and rotated, there is a risk that the connecting plate 241 will hit the screws 242, etc., depending on the shape of the curved portion 241c of the connecting plate 241. Even in this case, connecting plate 2
41, it is preferable to provide a guide plate 243 at the screw 242 that extends perpendicular to the plane of the paper and has a smoothly curved surface facing the connection plate 241.

A power input section 160 in FIG. 24 is provided in the printer lower unit 2. On the other hand, power input section 1
A main PSU 165 and a character PSU 166 connected to the printer 60 are provided in the printer unit 1. Therefore, the cable that connects these will be routed between the upper and lower units. This cable is protected by being covered around it by a metal spring tube 245, as shown at 244 in FIG. Since it is a spring tube, it is flexible and does not restrict the degree of freedom in bending the cable 244. In addition, since the tube is made of metal, the upper unit 1 of the printer is repeatedly opened and closed, and the spring tube 245 is attached to the lower frame 78.
Alternatively, even if the cable 244 rubs against the cover 8 (FIG. 13), the cable 244 will not be damaged.

Control process In this example, the main controller 1 shown in FIG.
The printing process and various processes associated therewith are controlled and executed by the CPU 186 of 76. The above-mentioned printing process, which includes steps such as charging, exposure, development, and transfer, is as explained in connection with FIG. 3.

We will now discuss some other important processes that accompany the printing process.

(Irregular Size Paper Print) In this embodiment, as shown in FIGS. 1 and 24, a rotary switch 192 for specifying the size of the transfer material is provided on the operation panel 5. This switch 192 specifies a paper size such as B5 or A4. In addition, in consideration of printing on envelopes of various sizes, it is also possible to specify an irregular size without specifying a particular size. The operator presses this size switch 192.
When the desired size, such as B5 or A4, is selected, the timing for transporting the transfer material for the printing process and the character arrangement settings (settings such as how many characters can be printed on one page) are set according to each size. . For example, for detecting a jam in the transfer material, the registration sensor 219, the paper ejection sensor 220
When the leading edge of the transfer material is detected by the same sensor and the trailing edge of the transfer material is not detected by the same sensor after a conveyance time commensurate with the size of the transfer material, it is determined that a jam has occurred. When an irregular size is specified, various timing settings for the printing process are performed based on the maximum size among the sizes that can be specified.

The above jam detection is performed when the size switch 192
If it is suitable for standard size paper such as B5 or A4,
It will be done without any problems. However, when the operator selects an irregular size to print on envelopes of various sizes, the registration sensor 219
There is a possibility that the above-mentioned jam detection using the above method may not be performed normally. Therefore, in this embodiment, when an irregular size is specified by the paper size switch 192, the jam detection operation is not performed to ensure smooth progress of the printing process.

In this case, the fact that jam detection is omitted is displayed by lighting the LED on the operation panel 5.

Incidentally, when setting the size switch 192 to an irregular size and printing on an envelope, it is also possible to program the temperature of the overheating roller 36 of the fixing device to be slightly lower than during normal printing. This is because envelopes are generally made by gluing, so if the fixing temperature is too high, the glue will melt. However, even in this case, care must be taken because lowering the temperature too much may result in poor fixing. Generally, a reduction of about 20% can prevent the adhesive from melting while maintaining sufficient fixing performance.

In the above explanation, when the irregular size is selected, the printing process is executed based on the maximum size transfer material, and the jam detection function is omitted. Apart from this control method, when an irregular size is specified, the process for the first transfer material is performed based on the largest size material, but the first transfer material is not conveyed. After the size of the transfer material is detected during the printing process, the printing process can be performed for the second and subsequent transfer materials based on the detected size. According to this method, high-speed printing can be performed in accordance with the size of the transfer material.

(Transfer material size abnormality notification) The operator can specify the paper size using the paper size switch 192. This designation is performed by selecting the same size as the transfer material placed on the paper feed tray 3. Therefore, normally the size specified by the switch 192 and the size of the transfer material on the paper feed tray 3 are the same. However, it is conceivable that the two sizes may be different due to an operator's switch setting error. In this case, if the printing process is carried out without any compensation,
For example, printing for B5 size may be performed on A4 size paper, resulting in too large a margin, or conversely, the paper size may not be sufficient for the number of prints.

In order to solve this problem, in this embodiment, when the printing process is started and the first sheet of transfer paper is conveyed into the printer, the size of the first sheet of transfer paper is checked, and the detected size of the first sheet of transfer paper is checked. If the size is different from the size specified by the switch 192, an LED display to that effect is displayed on the operation panel 5, and the printing operation is stopped.
This makes it possible to minimize the number of defective printed products.

In this case, the first sheet of transfer paper once sent into the printer is directly ejected to the outside by the ejection roller 40 or 45. In addition, to detect the transfer paper size,
A special sensor for this purpose may be prepared, or an existing sensor such as the registration sensor 219 may be used.

When an abnormality in the transfer paper size is notified as described above, at the same time the main controller 176
The CPU 186 is the character controller 180.
The CPU 184 is instructed to hold the print information that is currently being printed. Otherwise, the print information that has been painstakingly created will be lost due to an error in specifying the paper size.

(Photoconductor Unit Replacement Instruction Control) The OPC counter 250 disposed above the suction fan unit 49 in FIG.
7. Count the number of prints for each part related to cleaning (cleaning unit) such as the cleaning blade 55, etc.

OPC counter 250 is main controller 1
The count up is performed by the transfer command signal from 76, and when the count reaches 10,000, a signal to that effect is sent to the main controller 176 (Fig. 24).
The main controller 176 displays a photoconductor unit replacement display on the operation panel 5.
Furthermore, if the toner overflow sensor 221 (FIGS. 3 and 24) detects toner overflow before the count of the OPC counter 250 reaches 10,000, a notification to that effect is sent to the main controller 176, and the photoconductor is activated in the same way as above. A unit replacement display will be displayed.

On the other hand, in FIG. 4a, a protrusion 301 for identifying the unit is formed on the upper surface of the case 61 of the photoreceptor unit 58 that supports a new photoreceptor 11. As shown in FIG. This protrusion is detected by a type sensor 302 provided on the bottom surface of the printer upper unit 1 in FIG. When the photoconductor unit replacement display is displayed, if the unit identification protrusion 301 is detected by the type sensor 302 (i.e.,
(If the photoreceptor 11 has not yet been used 10,000 times),
"1" is displayed along with the photoconductor unit replacement display.

At the same time that "Photoconductor unit replacement "1"" is displayed, the latching solenoid 217 is turned on and its plunger is pulled down, thereby turning on the latch sensor 223. As long as the latch sensor 223 is on, “Photoconductor unit replacement “1”” continues to be displayed. Once turned on, the latch sensor 223 turns off at the same time when the reset lever 251 that resets the OPC counter 250 is reset as shown by arrow J (initial state). It is said that

For convenience, the display ``Photoconductor unit replacement ``1'' indicates that the photoconductor has been used 10,000 times. (Figure) is designed to have a capacity that is full of waste toner after 10,000 printings have been performed.Therefore, before the 10,000th printing is performed, toner overflow is detected and the photoconductor unit is replaced. If "1" is displayed, it is assumed that the photoconductor has been used 10,000 times.) Therefore, the operator who sees this display should
The cleaning unit in the photoreceptor unit 58 is replaced. The lifespan of the photoreceptor 11 is 20,000 cycles in the case of the example, and there is still 10,000 cycles left, so it will not be replaced. The photoreceptor 11 is removed from the photoreceptor unit 58 and only the cleaning unit is discarded.

When replacing the cleaning unit, replace the old photoconductor unit 58 with a new photoconductor unit 58 whose toner recovery tank 57 is empty, and attach the photoconductor 11 that has been used 10,000 times. Attach it to the predetermined position of the printer lower unit 2. Incidentally, the case 61 of the new photoreceptor unit is selected not to have the unit identification protrusion 301. Thereafter, when the operator presses the reset lever 251, the latch sensor 223 is initialized and at the same time the OPC counter is reset.
Therefore, from now on, the OPC counter starts counting from zero again. Even if the unit is replaced, the latch sensor 2 will remain closed unless the reset lever 251 is pressed.
23 is not initialized, and therefore the display of "Photoconductor unit replacement "1"" continues. In other words, the latch sensor 223 prevents forgetting to reset the OPC counter after replacing the unit.

Thereafter, printing is repeated, and when the OPC counter counts 10,000 times again or when toner overflow is detected, the photoreceptor unit replacement message is displayed again. However, since there is no unit identification protrusion 301 this time, the type sensor 302 will not detect it. Therefore, the display at this time will be something like "Photoconductor unit replacement '2'". This display indicates that the unit has been replaced for the second time, that is, the photoconductor has been used 20,000 times or close to it. This indicates that the life of the photoconductor itself has come to an end.Therefore, when the message "Replace photoconductor unit '2'" is displayed, the operator should replace the entire photoconductor unit 58 including the photoconductor 11 with a new one. do.

Transfer/Static Elimination Cleaner In this embodiment, as shown in FIG.
4 and the transfer charger 30 are arranged adjacent to each other. By using the cleaner 252 shown in FIG. 29, both can be cleaned at the same time. The upper transparent plate 253 of the static elimination lamp 54 is cleaned with felt 254 . Charge wire 2 of charger 30
05 is cleaned with a polishing cloth 255 made of polyurethane rubber or the like. When cleaning, place the felt 254 on the transparent plate 25.
3 and the polishing cloth 255 are simultaneously pressed against the charge wire 205, and in this state, the entire cleaner 252 is moved in a direction perpendicular to the plane of the paper. This removes toner and other debris. The clip 256 is attached to this cleaner 252.
This is for hanging it at an appropriate place inside the printer. The guide protrusion 257 is inserted into the lower frame 78 so as not to push the charge wire 205 etc. too much.
(FIG. 3) engages with an overhang (not shown).

Effects According to the present invention, even if the developing roller tries to approach the photoreceptor due to load fluctuations, its movement is restricted by the lock plate, and as a result, the distance or contact pressure between the photoreceptor and the developing roller becomes constant and stable. Now it is possible to perform high-quality development.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a laser printer according to an embodiment, FIG. 2 is a perspective view showing the upper unit of the laser printer shown in FIG. 1 in an open state, and FIG. 3 is a side sectional view of the laser printer. Fig. 4 is an exploded perspective view of the image forming unit of the laser printer, Fig. 5 is a plan view of the laser optical device, Fig. 6 is an optical path diagram of the laser optical device, and Fig. 7 is a partial perspective view of the developing unit. , FIG. 8 is a diagram of the meshing state of the gears, FIG. 9 is a perspective view of another part of the developing unit, FIG. 10 is a diagram taken along arrow X in FIG. 9, and FIG. 11 is a diagram of the developing roller. 12th exploded perspective view for explaining sealing means
The figure is an exploded perspective view showing a part of the printer lower unit, Figure 13 is an exploded perspective view showing a part of the printer upper unit, Figure 14 is a front view of a part of the ozone discharge device, and Figure 15 is a suction fan. A perspective view of the unit, FIG. 16 is an exploded perspective view of a part of the suction fan unit, FIG. 17 is a perspective view of the paper discharge guide member, FIG. 18 is a front view of the drive system, and FIG. 19 is the paper discharge roller. 20 is a perspective view of the paper ejection ring, FIG. 21 is a perspective view of the paper ejection path switching means, and FIG. 22 is a perspective view of the paper ejection path switching means.
The figure is a perspective view of a part of the positioning means of the unit on the printer, Figure 23 is a perspective view of the mirror fixing means of the laser optical device, Figure 24 is a control circuit diagram, and Figure 25 is a side cross-section of the high voltage connection terminal section. Figure 26 shows the installation state of the transfer charger, Figure 27 shows the upper
Cross-sectional view of one means of grounding the lower unit, 2nd
Figure 8 is a sectional view showing the two-stage rotating structure of the printer upper unit, Figure 29 is an explanatory diagram of the transfer/static elimination cleaner, Figure 30 is a side sectional view showing the state in which the optional paper feed unit is installed, and Figure 31. 32 is a perspective view of an example of the paper ejection roller, FIG. 33 is a perspective view of an example of the support means for the second cylindrical lens, and FIG. 34 is a perspective view of the second cylindrical lens.
A perspective view of the tip of the cylindrical lens attached.
FIG. 35 is a perspective view showing an example of how the photoreceptor unit is mounted, FIG. 36 is a cross-sectional view showing the completed state of the photoconductor unit, FIG. 37 is a perspective view of an example of the method of supporting the developing roller, and FIG. FIG. 3 is a front view of the lock plate. 11...Photoreceptor, 26...Developing roller, 96...
...Drive gear, 502...Lock plate.

Claims (1)

[Scope of Claims] 1. An image-forming unit case that is vertically movably supported on a main body frame by a pivot pin and supports a photoreceptor, and a developing unit that is removably attached to the image-forming unit case. The developing roller supported by the developing unit can be brought into pressure contact with the photoreceptor by pressing and moving the developing roller, and a driving gear of a gear train fixed in position on the main body frame is a gear provided on the shaft of the developing roller. In an electrostatic recording device that engages with and drives the developing roller, a lock plate is provided that can be positioned and fixed to the main body frame and rotatably fitted to the shaft of the driving gear, and the lock plate is arranged so that the shaft of the developing roller is aligned with the shaft of the developing roller. a recess into which the developing unit is placed; the recess has an arcuate inner surface having a predetermined distance from the circumferential surface of the shaft of the developing roller when the developing unit is in a predetermined position, and having an arcuate inner surface centered on the axis of the drive gear; An electrostatic recording device characterized by: 2. The arc-shaped inner surface is formed as a surface connecting an arc centered on the axis of the driving gear and an arc centered on a pivot pin supporting the imaging unit case, and the inner surface is formed as a surface that connects an arc centered on the axis of the driving gear and an arc centered on a pivot pin supporting the imaging unit case, and allows vertical movement of the imaging unit case. 2. The electrostatic recording apparatus according to claim 1, wherein the shaft of the developing roller is prevented from coming into contact with the lock plate.