JPH0451830B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to electrostatic recording in which development is performed while a photoreceptor and a developing roller are brought into contact with each other and are driven by a driving means provided at one end of the photoreceptor. Regarding equipment. Copying machines, printers, facsimile machines, and the like are known as this type of electrostatic recording device.

Prior Art In the electrostatic recording device described above, an electrostatic latent image formed on a photoreceptor is developed into a visible image using toner carried by a developing roller that rotates while in contact with the photoreceptor. The method in which development is performed while the photoreceptor and the developing roller are in contact is called the contact development method, which eliminates the need for a carrier, saves the trouble of replacing the carrier, allows the use of non-magnetic toner with good fixing properties, and further improves development performance. This has the advantage that the outline of the resulting visible image appears clearly (so-called sharpness).

However, in this contact development method, the contact pressure between the photoreceptor and the developing roller must always be kept constant, and if the contact pressure is unstable, it is conceivable that the best image cannot be obtained.

Purpose In view of the above points, an object of the present invention is to provide an electrostatic recording device that can always maintain stable contact pressure between a photoreceptor and a developing roller.

Structure The present invention achieves the above object by providing an electrostatic recording device that performs development while a photoreceptor and a developing roller that contacts the photoreceptor and is driven by a driving means provided at one end thereof are brought into contact with each other. at least two times to press the developing roller horizontally toward the photoreceptor.
This electrostatic recording apparatus is characterized in that it is provided with two horizontal pressing means and a vertical pressing means that presses the non-drive side portion of the developing roller in the vertical direction.

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. The operation panel 5 includes switches and the like for setting the size of the transfer material and various printing conditions. Front cartridge insertion slot 6
The system inserts a font cartridge, that is, a cartridge in which font information is stored, and sends the font information to a character controller, which will be described later. The emulation card insertion slot 7 is for connecting an emulation card to a character controller to match the host computer and this laser printer, depending on the type of host computer (not shown). be. The paper discharge switching knob 4 is used to switch between discharging the transfer material that has been printed inside the laser printer to the upper paper discharge tray 9, or discharging it to the left outside of 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
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, refracted upward by approximately 5 degrees, and is irradiated onto one surface of the polygon mirror 16. The laser beam thus irradiated is the second
The light is reflected by the mirror 21, passes through the second cylindrical lens 22, and is guided onto the photoreceptor 11. 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). This optical scanning is repeated for each surface of the polygon mirror 16,
At the same time, the photoreceptor 11 rotates in a direction perpendicular to the main scanning direction (sub-scanning direction), and as a result, the photoreceptor 11
An electrostatic latent image is formed corresponding to the image signal on the surface. In this embodiment, each surface of the polygon mirror 16 is curved so that the scanning image plane on the second mirror 21 is flat. Therefore, the so-called f-theta lens that was conventionally disposed between the polygon mirror 16 and the second mirror 21 is unnecessary. 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 generates 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 toner 29 contained in the developing tank 28 is supplied to the developing roller 26 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. 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, e.g. The paper 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 transport rollers 34 and 35, and further transported to the photoreceptor 11 by these transport rollers.
is transported to the transfer position.

The transfer paper conveyed 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, light from a 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 heating roller 36 and the pressure roller 37
The image is sent to a heat fixing device equipped with The transfer paper and the toner image transferred thereon are heated by a heating roller 36 and are subjected to pressure 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. A heater 38 is provided inside the heating roller 36 to heat the heating roller 36.

The transfer paper that has undergone the fixing operation is peeled off from the heating roller 36 by a peeling 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 experimental position shown in FIG. 3 and the paper ejection switching knob 4 shown in FIGS. Switch with the dashed line position. When the switching claw 41 is at the solid line position, the transfer paper coming out of the paper ejection roller 40 passes through the conveyance path formed by the paper ejection guide member 42 and the paper ejection guide plates 43 and 44, and passes through the upper paper ejection roller. Upper paper output tray 9 by 45
is discharged to. 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, when printing is performed in page order on weak plain paper transfer paper and it is desired to stack the sheets in page order, the upper paper discharge tray 9 is used for ejecting the paper. 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 by a static eliminating lamp 54 and scraped off from the photoreceptor 11 by a cleaning blade 55. The scraped off toner is sent into a toner collection tank 57 by a toner collection roller 56.
It can be 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 can be used in which carbon is mixed into the base of the roller such as Teflon. Since carbon has a relatively high hardness, this method can also increase the durability of the roller.

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.

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 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.

As can be seen from FIG. 4, the image forming unit case 60 is formed into a box shape with an open top, and a support shaft 62 of the photoreceptor 11 is mounted on the front and rear walls 60a and 60b.
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 the 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.

A pair of pivot pins 76 and 77 are protruded from the left wall 60d of the image forming unit case 60, and these pivot pins are connected to each frame 78 (FIGS. 1 and 3) of the printer lower unit 2. Side plates 78a, 78b
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 comes into pressure contact with 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 when transfer paper becomes jammed between the upper and lower transport rollers 34 and 35, it can be easily removed.

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.

When the image forming unit case 60 is installed, 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 as shown in FIG. 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, that is, the combined force P, is in the vertical direction. Since the acting force of the drive system is thus prevented from acting in the horizontal direction, the pressing force between the developing roller 26 and the photoreceptor 11 is no longer adversely affected by the acting force from the driving 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.

In FIG. 3, horizontal springs 109 and 110 are provided on the inner surface of the right end wall of the image forming unit case 60. The horizontal spring (which acts almost horizontally, but does not mean a spring that applies a spring force exactly in the horizontal direction) appears to be one in Fig. 3, but as shown in Fig. 4. , compression spring 10 on the front side
There are two springs in total, one compression spring 9 and one compression spring 110 on the back side (drive side). These springs press both ends of the case 66 of the developing unit 59 with spring forces P ₃ and P ₄ , respectively, as shown in FIG. 4b. on the other hand,
A vertical spring consisting of a compression spring 111 is applied to the part of the printer upper unit 1 corresponding to the non-driving side (the side without the gear 74) of the developing unit 59. The horizontal springs 109 and 110 are named to make it easier to distinguish them from the horizontal springs 109 and 110.
When the upper printer unit 1 is closed, this spring 111 presses the developing unit 59 downward at a portion on the non-drive side with a spring force _P5 .

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 to be appropriate values in consideration of the force acting on the developing roller shaft end gear 74 according to the applied developing unit 59 and other parts. For example, in consideration of the pressing force received by the developing roller drive gear 96, the drive side horizontal spring 110
The spring force of the horizontal spring 109 on the non-driving side is set to an appropriate value that is greater than the spring force of the horizontal spring 109, that is, a value that allows the developing roller to contact the photoreceptor with substantially uniform pressure over its entire length. Incidentally, in the example, P ₃
=700g, _P4 =100g, and _P5 =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 (in the diagonal diagram) 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 toner from leaking 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 122 on both the front and back sides.
a and 122b are provided in a protruding manner, and these small protrusions further improve the sealing performance of the side seal 115.

Drive System It has already been explained in connection with 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 drive 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 for adopting such an integrated structure 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.

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 bolts 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.

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 heating roller drive gear 99 shown in 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, it 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.

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.

A knob 22a that is pinched with human fingers when inserting and removing the second cylindrical lens 22.
is when the lens 22 is installed in a predetermined position,
Opening 2 of cover 8 similar to lock lever knob 10
48 to the outside. Since the opening 248 can be shared, the appearance is not impaired and workability is also good.

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 noise 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 at the front right side of the lower frame 78, as shown in FIG. 12, and is normally off, but turns 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 fingers cannot pass through it to prevent electric shock.

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 17 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.
7 power supply terminals 197 and 198 protrude (FIG. 2). The charging terminals 197, 198 have circular recesses 200 with claws 199 as shown in FIG.
and a spring terminal 201 which is accommodated in the recess in a state in which a preload is generated in advance. Terminals 195, 196 of the electrostatic charger etc. enter into the springs from the lower ends of the spring terminals 201 when both the upper and lower units 1, 2 are closed, and the spring terminals 201 are wrapped around the terminals 195, 196. Both 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. Also, the spring terminal and the terminal 195,
196 contact is also good. Furthermore, the spring terminal 20
1 is in a preloaded state by the claw portion 199, so 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 has been described with reference to FIG. 3. Controls the overall printer process such as charging, exposure, development, and transfer. The character controller 180 is attached to the electrical chassis 181 like the main controller 176, and is connected to the host computer 182.
(Fig. 24) is sent to the CPU 184 via the interface 183,
Here, a character signal is formed according to the character information. 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.

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 unit 186 drives the operation panel 5. In the case of this embodiment, as shown in FIG. Button switch 193 for giving various instructions, LED for various indications
A group 194 is provided. As shown in FIG. 13, this operation panel 5 is removably attached to the front surface of the electrical chassis 181, and
exposed to the outside. 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 opening 209 at a separate location with a cap.

The phase synchronization unit 187 drives the laser diode LD in the laser optical device 14 in synchronization with the printing process executed by the CPU 186. Further, a synchronization detection laser beam (described above) is received from the optical fiber 25 via the synchronization detection unit 189 to control 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 section 191 exchanges control data with the character controller 180, and also transmits a clock signal, which is a control reference, 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 drive motors, solenoids, etc. of each device. In this way, the main controller 17
The reason why a control voltage is specially created in 6 is to perform control using a clean power source with little pulsation. As a result, each printing process is executed without malfunction, and printed products with good print quality can be obtained.

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 is turned off and 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 2 (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 size is adjusted to a desired size such as B5 or A4, the timing of transporting the transfer material for the printing process is adjusted to match the size. For example, for detecting a jam in the transfer material, the registration sensor 2
19. It is determined that a jam has occurred when the trailing edge of the transfer material is not detected by the same sensor after a transport time commensurate with the size of the transfer material after the leading edge of the transfer material is detected by the paper ejection sensor 220 etc. It's becoming like that. If you specify an irregular size,
The timing is set based on the maximum size 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 indicated by lighting the LED on the operation panel 5.

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 paper 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. If the operator who sees this display immediately stops the printing process, the number of defective printed products can be minimized.

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.
Instructs the CPU 184 to keep 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.

Before the counter of the OPC counter 250 reaches 10,000, the toner over sensor 221 (Fig. 3, 2
4) detects toner overflow, a notification to that effect is sent to the main controller 176, and a photoreceptor unit replacement display is displayed in the same manner as above. At the same time, the latching solenoid 217 is turned on and its plunger is pulled down, thereby turning on the latching sensor 223. As long as the latch sensor 223 is on, the photoreceptor unit replacement display continues to be displayed. Once turned on, the latch sensor 223 turns off at the same time (initial state) when the reset lever 251 that resets the OPC counter 250 is reset as shown by arrow J.
It is said that

A photoconductor unit replacement display is displayed, and when the operator replaces the cleaning unit or photoconductor unit 58 in response to this and presses the reset lever 251, the latch sensor 223 is initialized and the OPC counter is reset at the same time. After that, the OPC counter starts counting again from zero. Even if the unit is replaced, the reset lever 2
As long as 51 is not pressed, the latch sensor 223 will not be initialized, and the photoreceptor unit replacement display will therefore continue. In other words, the latch sensor 223 prevents forgetting to reset the OPC counter after replacing a unit or the like.

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, since the photoreceptor and the developing roller are always in contact with each other under a constant pressure, it is possible to obtain an image with good uniform density and no white spots on the image.

[Brief explanation of drawings]

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
FIG. 8 is a sectional view showing the two-stage rotating structure of the printer upper unit, and FIG. 29 is an explanatory view of the transfer/static elimination cleaner. 11...Photoreceptor, 26...Developing roller, 74...
... Drive means (gear), 109, 110 ... Horizontal pressure means (spring), 111 ... Vertical pressure means (spring).

Claims (1)

[Claims] 1. An image forming unit case that supports a photoreceptor, a developing unit that can be detached from the upper side of the image forming unit case, and a horizontal spring that presses and moves the developing unit, and is supported by the developing unit by the horizontal spring. A developing roller shaft is provided on the shaft of the developing roller in a developing roller drive gear of a gear train which is capable of pressing a developing roller against the photoreceptor and is fixed in position to the lower frame supporting the image forming unit case. In the electrostatic recording device, the end gear is driven with its center positioned above a plane passing through the center of the developing roller driving gear, and the end gear engages with the end gear and applies an upward force to the developing unit. It consists of two springs provided near both ends, the driving side and the opposite non-driving side, and the spring force of each of the two springs is greater on the non-driving side than on the driving side. a vertical spring that is set to an appropriate value and that vertically pushes down the vicinity of the non-driving end of the developing unit; and a lock lever that locks the driving end of the developing unit so that it does not move in the vertical direction. An electrostatic recording device characterized in that the developing roller is in pressure contact with the photoreceptor with substantially uniform pressure over its entire length.