JPH0377972A - Color image forming device - Google Patents

Abstract

PURPOSE:To drive a belt-like image forming body at a stable carrying speed and to make a device itself simple and compact by making plural developing devices face a turnable roller while a transfer device faces the other turnable roller. CONSTITUTION:A color image forming device is provided with two turnable rollers 2 and 3, the belt-like image forming body 1 strung, rotated and supported by the turnable rollers 2 and 3, and image forming means disposed in a periphery thereof. The plural developing devices 8-11 face the turnable roller 2, on the other hand, the transfer device 12 faces the other turnable roller 3. Therefore, by forming an image forming plane, which is constituted of the flexible belt-like image forming body, of the peripheries of the turnable rollers driving the image forming body, the image forming body can be carried at a stable speed without receiving frictional resistance. Thus, a highly precise color image can be obtained and the device itself can be made simple and compact.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color image in which a toner image is formed on a belt-like image forming member by an electrophotographic method and transferred onto a transfer material to obtain an image. The present invention relates to a forming device.

[Background of the invention]

There are many ways to obtain color images using electrophotography.
A device has been proposed. For example, Japanese Patent Publication No. 61100770
As disclosed in the publication, a latent image is formed and developed in accordance with the number of separated colors of the original image on a photosensitive drum serving as an image forming member, and is transferred onto a transfer drum each time it is developed. There is a method of forming a multicolor image and then transferring it onto recording paper to obtain a color copy. A device using this method requires a transfer drum large enough to transfer one sheet of image onto its circumferential surface in addition to the photoreceptor drum, and the device does not have a large and complicated structure. It cannot be avoided.

For example, as disclosed in Japanese Patent Laid-Open No. 61-149972, a latent image is formed and developed on a photoreceptor drum according to the number of separated colors of the original image, and is transferred onto a transfer material each time it is developed. This is a method of obtaining multicolor copies. With this method, it is difficult to overlap multicolor images with high precision, and it is impossible to obtain high-quality color copies.

Another method is to repeatedly form a latent image on a photoreceptor drum according to the number of separated colors of the original image and develop it with color toner, and then transfer the color toner images overlapping each other on the photoreceptor drum to obtain a color image. . The basic process of forming a multicolor image is disclosed in Japanese Patent Application Laid-open No. 60-75850 and No. 60-7 by the present applicant.
No. 6766, No. 60-95456, No. 60-9545
No. 8, No. 60-158475, etc.

In a multicolor image forming apparatus that obtains a color image through such superimposition, color toners of different colors are stored around the periphery of a photoreceptor drum, and a plurality of developing devices are arranged. , generally the photoreceptor drum is rotated multiple times,
A color image is obtained by developing the latent image on the photosensitive drum.

As for image forming bodies, as explained above, there are photosensitive drums with a photoconductor coated or vapor-deposited on the circumferential surface of the drum, and belt-shaped image forming bodies with a photoconductor coated or mounted on a flexible belt. has also been proposed. The shape of the belt-shaped image forming body (hereinafter also referred to as a photoconductor belt) is determined by stretching it between rotating rollers including a drive roller, so it is possible to effectively utilize space and create a compact color image forming apparatus. It is effective when configured. Also, since the photoreceptor belt can run along a small curvature,
By using a rotating roller with a small diameter and separating the transfer material using this curvature, it is also possible to prevent poor separation of the transfer material.

[Purpose of the invention]

Since such a flexible belt-like image forming member constitutes a constant image forming surface, it is conveyed while slidingly contacting a fixed member usually called a guide member.

This creates a large frictional resistance during conveyance, so a strong driving force is required to maintain a stable conveyance speed.Furthermore, especially in the case of color image forming apparatuses, multiple developing units are used, so a large image forming surface is required. Therefore, a large guide member must be provided, and as a result, it has been difficult to realize a color image forming apparatus with a simple and compact structure.

As a result of solving and improving this point, the present invention makes it possible to configure an image forming surface without the above-mentioned frictional resistance, etc.
Therefore, it is an object of the present invention to provide a compact color image forming apparatus that can drive a belt-shaped image forming member at a stable conveyance speed.

[Structure of the invention]

The above object is to provide a color image forming apparatus that includes a plurality of rotating rollers, a belt-like image forming member supported by the rotating rollers, stretched and rotated, and an image forming means disposed on the peripheral edge thereof. While multiple developing units face the moving roller,
This is achieved by a color image forming apparatus characterized in that a transfer device faces the other rotating roller.

〔Example〕

An embodiment of the color image forming apparatus of the present invention is shown in FIGS. 1 to 8.

In FIG. 1, reference numeral 1 denotes a flexible photoreceptor belt which is a belt-like image forming member. transported to.

The rotary roller 2 is preferably a hollow roller having an outer diameter of about 80 to 120 mm, and is rotated clockwise by the power of the main body of the apparatus, and the photoreceptor belt is wound around more than half a circumference. The photosensitive surface on one outer periphery is part of the image forming surface. If the outer diameter is small, it becomes difficult to arrange a plurality of developing devices, and if the outer diameter is too large, the unit including the photoreceptor belt becomes large.

On the other hand, since the rotating roller 3 performs separation, it is preferable to have a small diameter.On the other hand, since the cleaning device 13 is installed, it needs to have a dimension larger than a certain value, and the preferred outer diameter is 2.
It is 0 mm to 50 mm.

6 is a scorotron charger which is a charging means; 7 is a laser writing system unit which is an image exposure means; and 8 to 11 are developing devices which are a plurality of developing means each containing a developer of a specific color. The rollers are arranged opposite to the photosensitive surfaces on the outer periphery of the photoreceptor belt l which is kept in tension by the urging of the laser writing system unit 7 and each developing device. 2 is arranged on the photosensitive surface around which the photosensitive belt 1 is wound, so that the accuracy of the positional relationship with the photosensitive belt 1 is particularly maintained.

In addition to the optical system shown in the drawings, the laser writing system unit 7 may also include an optical system that integrates a light emitting section and a convergent light transmission body.

The developing units 8.9, IO, and 11 contain, for example, yellow magenta, cyan, and black developers, respectively, and the developing sleeves 8A, 9A, IOA, and IIA maintain a predetermined gap from the photoreceptor belt l. It has a function of visualizing the latent image on the photoreceptor belt l by a non-contact development method. Unlike contact development, this non-contact development has the advantage of not interfering with the movement of the photoreceptor belt.

12 is a transfer device, 12A is a static elimination bar 13
is a cleaning device which is a cleaning means, and includes a blade 13A of the cleaning device 13 and a toner conveying roller 13.
B is separated from the surface of the photoreceptor belt l during image formation.
; It is kept in this position and is brought into pressure contact with the surface of the photoreceptor belt l as shown only during cleaning after image transfer.

The transfer device 12 and the cleaning device 13 include a photoreceptor belt l that is wound around a rotating roller 3 that is different from the rotating roller 2.
In particular, the transfer device 12 is arranged so as to face the tangent at the bottom of the rotating roller 3, so that the transfer material having the image transferred thereon is easily separated from the photoreceptor belt l and moves straight. It is configured as follows.

The process of forming a color image by the color image forming apparatus is performed as follows.

First, the formation of a multicolor image according to this embodiment is performed according to the image forming system shown in FIG. In other words, the color image data input section (Figure 2 (a)) where the image sensor scans the original image.
) is processed by the image data processing section (FIG. 2 (b)) to create image data, which is then stored in the image memory (FIG. 2 (c)). Then, the image memory is taken out at the time of recording and sent to the recording section (FIG. 2 (d)).
For example, the image data is input to the color image forming apparatus shown in the embodiment of FIG.

That is, when a color signal output from an image reading device separate from the printer is input to the laser writing system unit 7, the laser writing system unit 7 outputs a laser beam generated by a semiconductor laser (not shown). is rotated and scanned by a polygon mirror 7B rotated by a drive motor 7A, and passes through an fθ lens 7C to mirrors 7D and 7E.
The optical path is bent by this, and the light is projected onto the circumferential surface of the photoreceptor belt l, which has been charged in advance by a charger 6 serving as a charging means, to form a bright line.

On the other hand, when scanning is started, the beam is detected by the index sensor, modulation of the beam by the first color signal is started, and the modulated beam scans the circumferential surface of the photoreceptor belt l. Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the photoreceptor belt l by the main scanning by the laser beam and the sub-scanning by the conveyance of the photoreceptor belt l. This latent image is developed by a developing device 8 loaded with yellow (Y) toner (developing medium) of the developing means, and a toner image is formed on the belt surface. The obtained toner image, while being held on the belt surface, passes under a cleaning device 13, which is cleaning means, which is separated from the circumferential surface of the photoreceptor belt 1, and enters the next copy cycle.

That is, the photoreceptor belt l is charged again by the charger 6, and then the second color signal outputted from the signal processing section is input to the writing system unit 7, and the second color signal is inputted to the writing system unit 7, and the second color signal is inputted to the writing system unit 7. In the same manner, writing is performed on the belt surface to form a latent image. The latent image is developed by a developer 9 loaded with magenta (M) toner as a second color.

This magenta (M) toner image is formed in the presence of the previously formed yellow (Y) toner image.

IO is a developing device having cyan (C) toner, and forms a cyan (,C) toner image on the belt surface based on a control signal generated by a signal processing section.

Further, numeral 11 denotes a developing device having black toner, which forms a black toner image superimposed on the drum surface by the same process. These developing units 8, 9, 10 and 11
A direct current or even alternating current bias is applied to each sleeve, and jumping development is performed using an l-component or two-component developer as a developing means, and non-contact development is performed on the photoreceptor belt 1 whose base is grounded. It is about to be done.

The color toner image thus formed on the circumferential surface of the photoreceptor belt l is transferred to a transfer material fed from the paper feed cassette 14 via the paper feed guide 15 at the transfer section.

That is, the top layer of the transfer material stored in the paper feed cassette 1-14 is carried out by the rotation of the paper feed roller I6, and is transferred via the timing roller 17 in synchronization with the image formation on the photoreceptor belt l. is supplied to the vessel 12.

The transfer material with the image transferred thereto is reliably separated from the photoreceptor belt l, which suddenly changes direction along the rotation roller 2, and heads to the left, and after the image is fused by the fixing roller 18, it is discharged. It passes through rollers 19 and is discharged onto tray 20 .

On the other hand, the photoreceptor belt l, which has completed the transfer to the transfer material, continues to be conveyed upward, and the remaining toner is removed by the cleaning device 13 in which the blade 13A and the toner conveying roller 13B are brought into pressure contact. The blade 13A is removed, and a little later, the toner conveying roller 13B is removed to begin a new image forming process.

The aforementioned photoreceptor belt 11 charger 6, cleaning device 1
3 including the rotation rollers 2 and 3 described above is housed between the front and rear substrates 3OA and 30B as shown in FIG.

That is, each of the boards 30A and 30B has three stays 3.
The bearing supports the rotary rollers 2 and 3 and the tension roller 5, which are integrated through the roller 1 and around which the photoreceptor belt 1 is wound, and also holds a charger 6 and a cleaning device 13 between them. .

The cartridge 30 is inserted horizontally into the main body of the apparatus from the front. A handle 35 attached to the front is used for insertion.

Two shafts, a driving shaft and a fixed shaft, are provided inside the main body of the device, and are fitted to the respective shaft centers of the rotary rollers 2 and 3.
The cartridge 30 is supported and attached to the main body of the apparatus by fitting the rotary rollers 2 and 3 onto the outside.

FIG. 4 shows a cross section taken along the line AA in FIG. It is supported by ribs R1 and R2 in a loosely fitted state, respectively.

On the other hand, a drive shaft 2A and a fixed shaft 3A having a gear G connected to the power system of the device are protruded from the main body of the device.
By fitting the rotary rollers 2 and 3 onto the fixed shaft 3A and the fixed shaft 3A, the cartridge 30 is supported, and at the same time, the position and spacing of the rotary rollers 2 and 3 are determined. The photosensitive surface is also set at a predetermined position.

The drive shaft 2A and the fixed shaft 3A are connected to each rotary roller 2 and 3.
After passing through, the nut 2B is tightened to fix the rotary roller 2 to the drive shaft 2A to make it integral, and the rotary roller 3 is held rotatably with respect to the fixed shaft 3A by attaching the nand 3B.

It is assumed that the cartridge 30 itself is also held by locking either the substrate 3OA or 30B to the apparatus main body after being attached to the apparatus main body.

FIG. 5 shows the structure for setting the relative position of each image forming means with respect to the photoreceptor belt l. Regarding the developing means, its main part is shown in FIG. Regarding the exposure means, an optical system having a convergence transmitter is shown in FIG. 5(B) in a YY section.

9A in FIG. 5(A) is the developing sleeve of the developing device 9;
Reference numeral 9B denotes an abutting roller as an abutting member, and the abutting roller 9B is rotatably supported by a bearing on the rotating shaft 9c of the developing sleeve 9A. When the abutting roller 9B is pressed against the rotary roller 2, the abutting roller 9B is moved from the developing sleeve 9A so that a gap corresponding to the developing gap can be formed between the circumferential surface of the developing sleeve 9A and the outer circumferential surface of the photoreceptor belt l. It has a slightly larger outer diameter.

Therefore, the developing sleeve 9A has a constant developing interval (0.3 to 1
mm), and the developing device 9 can always perform proper developing process. Note that the same applies to the other developing devices 8 and 10.11, and the abutment rollers incorporated therein are pressed against the rotating roller 2 by a biasing mechanism described later.

The structure and function of each developing device will be explained using the developing device 9 as an example.

FIG. 6 shows a cross section of the developing device 9. 9A is a developing sleeve containing a magnetic roller, and a predetermined developing interval is maintained between the developing sleeve and the circumferential surface of the photoreceptor belt l by coaxial abutment rollers 9B. It is driven and rotated counterclockwise. 19A is a rigid and magnetic thin layer forming member that is pressed against the developing sleeve 9A with a predetermined load without the presence of developer. Reference numerals 19B and 19C are a pair of toner conveying screws having a screw structure and conveying and circulating the developer in mutually opposite directions, which function to sufficiently stir and mix the toner and carrier and send the resulting developer to the developing sleeve 9A. .

The toner conveyance screw 19B and the toner conveyance screw 19c are members that also serve as stirring members that rotate in opposite directions, and the toner and carrier conveyed to the back side by the thrust of the toner conveyance screw 19c are transferred to the toner conveyance screw 19B side. The developer is conveyed to the front side of the drawing by the thrust, and is triboelectrically charged and homogeneous by the mixing action of the toner and carrier during that time. adhere to.

This thin layer of developer adheres to the circumferential surface of the developing sleeve 9A, and forms a latent image on the circumferential surface of the photoreceptor pel +-i, which is conveyed clockwise in the developing area, at the above-mentioned development interval. A toner image is formed by reversal development in a non-contact manner.

During this non-contact development, a developing bias containing a direct current or an alternating current component is applied from a power supply (not shown) to the developing sleeve 9A, and only the toner in the developer is selectively applied to the surface of the latent image on the image sleeve 9A. Transferred and attached.

The developer whose toner components have been consumed has a higher carrier ratio and is conveyed by the developing sleeve 9A to the scraper 19.
It is peeled off and collected by step D, and then mixed with a developer having a high toner ratio again.

On the other hand, reference numeral 17 shown in FIG. 5(B) is an image exposure means, which consists of an optical system that integrates a convergent light transmitter 17A and a light emitting section 17B such as an LED, and the light emitting section 17B projects from both ends of the casing. A protrusion 17c having a predetermined height is integrally formed as this member.

The optical system 17 is biased by an elastic member such as a leaf spring so that each of the protrusions 17C comes into pressure contact with the rotary roller 2 on the outside of the photoreceptor belt l.

Therefore, the optical system 17 is also always positioned at a constant distance from the circumferential surface of the photoreceptor bell l-1, so that an image can be accurately formed on the photoreceptor.

Furthermore, regarding the photoreceptor belt 1, it is shown in FIG. 5(A).

As shown in (B), a pair of continuous guide rails IA are integrally formed on the inner periphery of the photoreceptor belt, and the guide rails IA are engaged with the guide grooves 4 of the rotating roller 2, so that the photoreceptor belt is easily generated during conveyance. This prevents meandering of l.

Further, each of the developing units is provided with pairs of moving rollers 29B on the bottom surface of the housing 29A, as shown in the example of the developing unit 9 shown in FIG. 6. It is built in so that it can move horizontally within the garage 40.

As mentioned above, the rotary roller 2 has an outer diameter of about 80 to 120 mm, and the rotary roller 3 has an outer diameter of about 20 to 50 mm, while each developing device is thinned to a vertical height of about 20 mm. Therefore, each developer is assembled in a stacked state in the developing garage 40 as shown in FIG.
Each of the abutting rollers can be appropriately pressed against the photoreceptor belt I around which the photoreceptor belt I is wound, thereby forming a required development interval between the rollers and the developing sleeve.

Further, the right side of the developing device 9 is connected to a toner box 39A.
The toner for replenishment contained in the toner box 39A is supplied into the developing device by the rotation of the toner replenishing roller 39B and the sponge roller 39C.

Furthermore, the developing device 9 is configured to move the regulating pin 29D on the protrusion 29C on the right outer surface of the housing 29A to the developing garage 40.
It is engaged with a grooved cam 43 of a cam plate 42 that is integrated with a rotating shaft 41 provided in the.

When the rotating shaft 4■ is in the clockwise rotated position, the groove cam 43 of the cam plate 42 moves the developing device 9 to the left, that is, toward the photoreceptor belt l side, via the regulating bin 29D. Further, with the regulation bin 29D in a free state, the image forming device 9 is urged to the left, that is, in the direction of the photoreceptor belt l, by the action of the tension spring 44 stretched between it and the developing garage 4D, as described above. The position of the developing sleeve 9A with respect to the photoreceptor belt 1 is set by bringing the abutting roller 9B into contact with the rotating roller 2.

On the other hand, when the rotary shaft 41 is rotated half a turn counterclockwise, the grooved cam 43 moves the developing device 9 to the right through the regulating bin 29D, that is, in a direction in which it is retracted away from the photoreceptor belt l. The force-string 30 can be attached to and detached from the main body of the device.

Note that by moving each developer individually to the right, it is possible to open the shielding plate 39D as in the example of the developer 9 shown in FIG. 7, and therefore the toner box 39A can be replenished with toner. becomes.

Further, in the color image forming apparatus of the present invention, it is also possible to arrange the current IgA devices in parallel in the horizontal direction below the driving rotary roller that conveys the photoreceptor belt.

FIG. 8 shows an example of a color image forming apparatus having such an arrangement.
02 shows a configuration in which a pair of driven rotary rollers 103 are disposed laterally above the transfer roller 102, and the conveying surface of the transfer material is provided horizontally.

In this example as well, the rotating rollers 102 and 103
The cartridge 130, which supports the image forming means including the charger 106 and the cleaning device 113, is moved downward by operating the developing garage 140, which has the same function as the previous example. It is inserted and installed more horizontally.

By adopting such an arrangement, it is possible to reduce the floor space occupied by the main body of the apparatus, and it is also possible to prevent toner from flowing out and scattering when handling the developing device.

Furthermore, since the conveying surface of the transfer material is horizontal and located above the main body of the apparatus, copying operations are facilitated.

〔Effect of the invention〕

The present invention stabilizes the image forming body without receiving frictional resistance by forming the image forming surface of the flexible belt-like image forming body by the circumferential surface of a rotating roller that drives the image forming body. As a result, a color image forming apparatus has been provided which can obtain highly accurate color images and which can also simplify and downsize the apparatus itself.

[Brief explanation of drawings]

1 and 8 are cross-sectional configuration diagrams of a color image forming apparatus of the present invention, and FIG. 2 is a block diagram showing an image forming system.
3, 4, and 5 are a front view, a cross-sectional view, and a cross-sectional view of a main part of a cartridge of the apparatus, FIG. 6 is a cross-sectional view of a developing device, and FIG. 7 is a front view of a developing garage. l... Photoreceptor belt 2.3, IO2, ]03... Rotating roller 5... Tension roller 6,106... Charger 7.107.
...Laser writing system unit 9B...Developing sleeve 8.9.10, 11, 108.109. lol, ill
...Developer 12.112...Transfer device 13.113...Cleaning device 14.114...Paper feed cassette 16.116...
Paper feed roller 17,117...Timing roller 18,118...Fixing roller 19,119...
Paper ejection roller 20.120...Tray 30.
... Cartridge 30A, 30B... Board
31... Stay 35... Handle 40.
...Development garage 40A...Support stand 42
...Cam plate 43...Groove cam

Claims (2)

[Claims] (1) In a color image forming apparatus comprising a plurality of rotating rollers, a belt-like image forming body supported by the rotating rollers, stretched and rotated, and an image forming means disposed on the peripheral edge thereof, the rotating A color image forming apparatus characterized in that a plurality of developing devices face a roller, and a transfer device faces another rotating roller. (2) The color image forming apparatus according to claim 1, wherein after forming a color toner image on the belt-like image forming member, the color toner image is transferred onto a transfer material.