JPH02311853A - Color process cartridge - Google Patents

Abstract

PURPOSE:To eliminate the need for an energization device and to set the developing sleeve of each developing device with a correct space between the sleeve and an image forming body surface by constituting each developing sleeve of the developing device unit in such a manner that a fixed space between the sleeve and the image forming body surface is held. CONSTITUTION:The developing device unit 100 has such a shape that it is deformed slightly inward and contracted so that the developing sleeves 361, 371, 381, and 391 of respective developing devices are uniformly brought into contact with a periphery, whose curvature is slightly smaller than that of the periphery of the photosensitive drum 30, at the time of a single body. When butting rollers 361A, 371A, 381A, and 391A provided on the same axis of corresponding developing sleeves so as to place them on the position facing the periphery of the photosensitive drum 30, are brought into press-contact with the periphery of the photosensitive drum 30, the developing unit 100 expands to the right and left to cause butting rollers to be uniformly brought into contact with the periphery of the photosensitive drum 30 with uniform pressure; consequently, respective developing sleeves 361, 371, 381 and 391 can be set in a position with a correct space for development to the image forming body by using a considerably simple means.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a process cartridge for a color image forming apparatus that incorporates a plurality of developing devices.

[Background of the invention]

An electrophotographic image forming apparatus that forms a multicolor image such as a full color image or a functional color image includes a charger that charges a photoreceptor drum that is an image forming member, an image exposure unit that exposes an image to the photoreceptor drum, and a photoreceptor. A developing device that develops the electrostatic image on the photosensitive drum with toner, a transfer device that transfers the toner image on the photosensitive drum onto recording paper, and the like are arranged around the photosensitive drum.

Among these, the developing units in full-color electrophotographic image forming apparatuses are comprised of three or four developing units each containing yellow (Y), magenta (M), cyan (C) toner, and sometimes black (BK) toner. It consists of a developing device, and while the photosensitive drum rotates three or four times,
Yellow (Y), magenta (M), cyan (C), and black (BK) toner images are formed on the photosensitive drum, and these toner images are transferred to recording paper to obtain a full-color image. There is. When using such an image forming method, the color image forming apparatus can be made compact by making three or four developing units thin and arranging them close to each other.

Japanese Unexamined Patent Publication No. 61-55661 proposes a color image forming apparatus using such an image forming method, in which latent images are formed by three exposure devices corresponding to three current devices, and a photoreceptor drum and The developing device and the cleaning means are integrated into a unit and can be taken out from the main body of the apparatus as a process cartridge.

Furthermore, Japanese Patent Application No. 62-320596 discloses a system in which one exposure device is used and the developing devices are placed one on top of the other, and the unit is made into a unit that can be taken out from the main body of the device.

[Problem that the invention seeks to solve]

Each developing device of a color image forming apparatus used in this way is usually manufactured as an integral structure and handled as a developing device unit, and is usually constructed so that it can be easily attached to and removed from the process cartridge. .

However, when each developing device is housed in a process cartridge, it is necessary to urge the curved surface of the developing sleeve to a position that maintains an accurate developing interval with respect to the image forming body surface by means such as well-known pressure contact with abutting rollers. When the developing devices are integrated as a developing unit as described above, a device for energizing the developing device must be provided individually in each developing device, and the structure inside the developing device becomes extremely complicated. In addition, it may also cause operational troubles.

As a result of solving this problem and improving the present invention, the present invention provides an image forming apparatus in which the developing sleeve of each developing device can be set at an accurate developing interval with respect to the surface of the image forming body without requiring any particular urging device. The purpose is to provide color process cartridges.

[Means for solving problems]

The above object is to provide a color process cartridge in which a plurality of developer units are provided at least on an image forming body and a peripheral portion thereof, wherein the plurality of developer units are integrally molded from a resin having elasticity and This is achieved by a color process cartridge characterized in that it faces the image forming body with a pressing force of 1, and each developing sleeve of the developing device unit is formed at a constant distance from the surface of the image forming body.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 to 6.

FIG. 1 shows an embodiment in which the present invention is applied to a printer.

The printer is divided into an upper housing l containing a transfer belt and an apparatus main body 2 containing a color process cartridge.
The gram shell has the following structure, and the upper housing l can be held open at a predetermined angle by a hinge connected to the device main body 2, and in the closed state, it is integrated with the device main body 2 by a locking metal fitting. .

A photosensitive drum 30 as an image forming body constituting the image forming section of the printer, developing units 36, 37, 38, and 39 containing yellow, magenta, cyan, and black developers, and a pressure releasing mechanism for the image forming body. A cleaning device 14 having
In addition, each component of the charger 35 is housed in an integrated color process cartridge 3 to form a unit.

The unitized process cartridge 3 has a second
As shown in the figure, by opening the upper case l, it is vertically inserted into the device main body 2 from above, and the bottom holder is inserted into the base 4.
After being placed in the upper case 1, it is fixed at the storage position by the action of a pressing member (not shown) that is linked to the closing of the upper housing 1.

The developing devices 36, 37, 38, and 39 housed in the color process cartridge 3 occupy symmetrical positions with respect to the rotation axis of the photosensitive drum 30, which is an image forming member, and then rotate so as to face the circumferential surface of the photosensitive drum 30. The developer units 100 are housed as a plurality of developing unit units 100 arranged vertically in sequence from the upstream direction.

Therefore, since all of the developing devices are maintained with their openings facing upward, the developer does not leak out and fall or get mixed into other developing devices.

The printer has a laser writing system unit B in a space on the side of the process cartridge 3, and a recording paper conveying surface in a part above the process cartridge 3 that spans both the upper housing 1 and the main body 2 of the apparatus. We have set up
The photosensitive drum 30 is subjected to laser scanning by the laser writing system unit B from diagonally downward, and a color toner image formed on the circumferential surface thereof is superimposed and transferred to the lower surface of the recording paper.

The process of color image copying by the printer 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. That is, the color image data input section (Fig. 3 (a)) where the image sensor scans the original image.
) is processed by an image data processing unit equipped with a computer (Figure 3 (b)) to create image data, which is then stored in the star image memory (Figure 3 (c)). Stored. Then, the image memory is taken out during recording and stored in the recording section (
For example, the color image forming apparatus shown in FIG. 1 is inputted as shown in FIG. 3(d)).

That is, when a color signal output from an image reading device separate from the printer is input to the laser writing system unit B, the laser writing system unit B outputs a laser beam generated by a semiconductor laser (not shown). The peripheral surface of the photosensitive drum 30 is rotated and scanned by a polygon mirror 32 rotated by a drive motor 31, the optical path is bent by a mirror 34 via an fθ lens 33, and the peripheral surface of the photosensitive drum 30 is charged in advance by a charger 35 serving as a charging means. It is projected upward and forms 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 is transferred to the photoreceptor drum 30.
scan the circumferential surface of the Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the photoreceptor drum 30 by main scanning by the laser beam and sub-scanning by the rotation of the photoreceptor drum 30. This latent image is developed by a developing device 36 loaded with yellow (Y) toner (II image medium) of the developing means, and a toner image is formed on the drum surface. The obtained toner image passes under a cleaning device 40, which is a cleaning means, which is separated from the peripheral surface of the photosensitive drum 30 while being held on the drum surface, and enters the next copy cycle.

That is, the photosensitive drum 30 is charged again by the charger 35, and then the second
The color signal is input to the writing system unit B, and writing is performed on the drum surface to form a latent image in the same manner as in the case of the first color signal described above. The latent image is developed by a developer 37 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.

A developing device 38 has cyan (C) toner, and forms a cyan (C) toner image on the drum surface based on a control signal generated by a signal processing section.

Furthermore, 39 is a developing device having black toner, and a black toner image is superimposed and formed on the drum surface by the same process. Direct current or even alternating current bias is applied to each of the sleeves 36, 37, 388, and 39 of these current devices, and jumping development is performed using a two-component developer as a developing means, and the photoreceptor whose base is grounded is Development is performed on the drum 30 without contact.

The color image thus formed on the circumferential surface of the photoreceptor drum 30 is re-charged by the charger 9 and then transferred to the lower surface of the recording paper fed from the paper cassette C via the paper feed roller and the paper feed guide at the transfer section. transcribed.

That is, after this multicolor toner image is charged by the pre-transfer charger 9 to be easily transferred, the transfer belt 50, which has been rotating since the start of transfer, is brought into contact with the photoreceptor drum 30.
The image is transferred to a recording sheet fed from a paper cassette C via a paper feed roller 12 and a timing roller 13 in synchronization with image formation.

The structure of the transfer belt 50 is that a 0.5 mm thick elastic layer is provided on the outer periphery of a conductive cloth-containing rubber belt as a base, and a 50 μm insulator layer (dielectric layer) is further provided on the outer periphery of the rubber belt with vignetting, rollers 60a, 60b, 60c (1) is rotated by the drive of the roller 60a, and the roller 60
As b moves up and down, the transfer pel l-50 comes into contact with or separates from the photosensitive drum 30. The transfer belt 5o is charged by a transfer device 51, and the surface of the transfer belt 50 is charged with electricity.
．． 5KV~3. Transfer is performed by applying a transfer charge having a polarity opposite to that of the toner of about OKV. 866 is the transfer belt 5
This is a cleaning device for the transfer belt that cleans the top surface of the transfer belt.

On the other hand, the photosensitive drum 3 with the recording paper separated from the drum circumferential surface
At 0, the blade 40A of the cleaning device 40 comes into contact and removes the remaining toner, and when that is finished, it is separated from the drum circumferential surface again and a new color image format process begins.

In this way, the recording paper is conveyed horizontally over the top of the process cartridge 3, and the transfer surface is also facing downward, so even if the toner spills or scatters from the cleaning device 40 or the like, the image surface will be contaminated. I never get to the point where I do it. The recording paper that has been transferred is transferred to the fixing roller 80. The paper is discharged to the outside via a paper discharge roller 90.

The developing device unit) 100 includes each developing device 36, 37, 3.
Developing device housings 36A, 37A, 88 and 39, respectively;
38A and 39A are integrated in series as shown in FIG. 4(a), and are molded from a synthetic resin material with appropriate elasticity by providing a cut S between each developer housing. .

Further, when the developing device unit 100 is used as a single unit, each developing device has a built-in developing sleeve 36i, '371.381.
and 391 are deformed slightly inward to uniformly contact the cylindrical surface with a curvature slightly smaller than the curvature of the photoreceptor drum 3o on the circumferential surface of the photoreceptor drum 3o, exhibiting a reduced shape, and facing the situation of the photoreceptor drum 30. Each abutting roller 361A is provided on the same axis of each developing sleeve so as to be placed in the same position.

371A, 381A and 391A photosensitive drum 3o
When pressed against the circumferential surface of the photoreceptor drum 30, the developer unit loo expands to the left and right as shown in FIG. Each developing sleeve is set at a position that constitutes an accurate developing interval.

Further, in the developing device unit 100, after each developing sleeve is placed at its respective setting position, each developing device is supported by plate-shaped elastic members PI, P2, and P3 provided on the inner bottom surface of the color process unit 3, and is exposed to light. The relative position relative to the body drum 30 is maintained.

Further, FIG. 4(c) shows another embodiment, in which the developing unit 100A is deformed slightly inwardly so as to uniformly contact a cylindrical surface having a curvature slightly smaller than the curvature of the drum. Main body 101A made of elastic resin with a shape
In contrast, a front plate 102A and a rear plate 103A are glued or screwed together with machine screws 104A at the front and rear.
36A, 37A, 38A, and 39A are developing unit housings of the respective developing units 36, 37, 38, and 39. The position relative to the photosensitive drum 30 is the same as that of the elastic member Pi.
, P2° is held by P3.

Figure 5 shows each developing device 136, 137, 13 manufactured individually.
8 and 139 are housed in a casing 200A molded from a synthetic resin material having appropriate elasticity similar to the developer unit 1-100.
An example of 00 is shown.

The developer unit 200 also includes each developer 136, 13.
The development interval of each developing sleeve is set by pressing the abutting rollers 138 and 139 against the circumferential surface of the photoreceptor drum 30, and in the color process cartridge 3, it is the same as in the case of the developer unit 100 in the previous example. Each developer is supported by an elastic member to maintain its relative position with respect to the photoreceptor drum 30.

The structure and function of each developing device will be explained using the developing device 36 as an example.

FIG. 6 shows a cross section of the developing device 36 in the developing device housing 100, and 361 is a developing sleeve containing a magnet roller, which is connected to the circumferential surface of the photoreceptor drum 3o by a coaxial abutting roller 361A. It is driven and rotated in a clockwise direction with a predetermined development interval maintained in between. Reference numeral 362 denotes a rigid and magnetic thin layer forming member that is pressed against the developing sleeve 361 with a predetermined load without the presence of developer. 36
Reference numerals 3 and 364 are a pair of toner conveying screws that have a screw structure and transport and circulate the developer in opposite directions, and function to sufficiently stir and mix the toner and carrier and then send the toner and carrier as developer to the developing sleeve 361. .

The toner conveyance screw 363 and the toner conveyance screw 364 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 363 are transferred to the toner conveyance screw 364. The developer is transferred to the front side of the drawing by its thrust, and the mixture of toner and carrier therebetween becomes a homogeneous developer that is triboelectrically charged and adheres to the circumferential surface of the developing sleeve 361 in a layered manner.

A thin layer is formed by adhering to the circumferential surface of the developing sleeve 3 (il).
: This developer layer develops the latent image on the circumferential surface of the photosensitive drum 30 rotating in the direction of the arrow in the developing area in a non-contact manner at the above-mentioned development interval to form a toner image.

During this non-contact development, a developing bias containing an AC component is applied to the developing sleeve 361 from a power source (not shown),
On the image forming sleeve 361, only the toner in the developer is selectively transferred and adhered to the surface of the latent image.

The developer whose toner components have been consumed has a higher carrier ratio and is transported by the developing sleeve 361 to the scraper 3.
The toner is peeled off and collected by step 65, and then mixed with a developer having a high toner ratio again.

〔Effect of the invention〕

The present invention makes it possible to set each developing sleeve of a plurality of developing devices at a uniform position with respect to an image forming body using extremely simple means and at a position where an accurate developing interval can be established. The structure of the image forming device has been significantly simplified, reducing manufacturing costs, and maintenance work has become easier, providing a color process cartridge for an image forming apparatus that is easy to handle.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of an image forming apparatus having a color process cartridge of the present invention, FIG. 3 is a block diagram showing an image forming system, and FIGS. 4(a), (b), and 5 are 4(c) is a perspective view of a developing device unit of another embodiment; FIG. 6 is a sectional view of the developing device included in the unit. 1... Upper housing 2... Apparatus main body 3... Color process cartridge 30... Photosensitive drum 36, 37, 38, 39... Developing units 36A, 37A, 38A, 39A... Developing Device housing 100.200...Developer unit 200A...Casing

Claims (1)

[Claims] In a color process cartridge in which at least an image forming body and a plurality of developer units are provided in the peripheral area thereof, the plurality of developer units are integrally molded from an elastic resin, and the image forming unit is formed with a pressing force due to the elasticity. A color process cartridge, characterized in that each developing sleeve of the developing device unit faces the image forming body and is configured to maintain a constant distance from the surface of the image forming body.