JPH02262672A - Color image forming device - Google Patents

Abstract

PURPOSE:To improve the maintainability by constituting a process unit by uniting an image formation body, a group of developing devices which are distributed on the right and left sides of the image formation body center line and provided below it, and a cleaning device, and enabling the process unit to be attached to and detached from a device main body. CONSTITUTION:Respective members, i.e. the image formation body 30 which constitutes the image formation part of a printer, the developing devices 36 to 39 which contain developers of yellow, magenta, cyan, and black, the cleaning device 40 which has a pressing and releasing mechanism for the image formation body, and an electrostatic charger 35 are put in the process cartridge 3 and united, and then stored in the device main body 2 through a couple of guide members 4 which engage the right and left external surfaces so that the device can be inserted and extracted. The process cartridge 3 can be united into compact structure with good handling while the distribution of the weight and the balance of a power system are maintained. Consequently, various maintenance operations such as toner supply control can be performed extremely easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image forming apparatus using electrophotography, and more particularly, to a color image forming apparatus that is miniaturized, has improved maintenance performance, and has improved jam processing performance. .

[Conventional technology]

An electrophotographic image forming apparatus that forms a multicolor image such as a full color image or a funxional 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 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 devices in the electrophotographic image forming apparatus for full-color images are three or four developing devices each containing yellow (Y), magenta CM), cyan (C) toner, and sometimes black (BK) toner. While the photosensitive drum rotates 3 or 4 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 developing 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. In addition, a patent application published in 1982-32 used two exposure devices, arranged the developing devices one on top of the other, and made it into a unit that could be taken out from the main body of the device.
It is described in the specification of No. 0596.

The above-mentioned Japanese Patent Application Laid-Open No. 61-55661 and Japanese Patent Application No. 1983-
Although the color image forming apparatus described in the specification of No. 320596 contributes to improved maintainability, it is easy for developer to spill or get mixed in when the unit is inserted or removed.

Furthermore, Japanese Patent Application Laid-Open No. 72159/1983 describes an example in which the area around the photosensitive drum is formed into a unit in a color image forming apparatus that uses a transfer drum to transfer each color toner image to a recording paper.

[Problem that the invention seeks to solve]

However, in the color image forming apparatus described in Japanese Unexamined Patent Publication No. 58-72159, (1) the image forming section extends not only around the photosensitive drum but also onto the transfer drum.

(2) The circumferential speed and gap between the photosensitive drum and the transfer drum must be maintained with high accuracy.

(3) A release mechanism is required to take out the photoreceptor drum.

As described above, in a color image forming apparatus using a transfer drum, the mechanism is not only complicated and expensive as described in (2) and (3) above, but also the image forming apparatus is difficult to form, as in a monochrome image forming apparatus that does not require a transfer drum. Since the means are not concentrated around the photoreceptor, the advantages of unitization (process unit) in the image forming section cannot be fully obtained.

The present invention improves maintainability by integrating the developing unit, the image forming body, and the cleaning means, or by forming a cartridge structure in which two of them are integrated and the remaining one is independently insertable and removable. , and to prevent the developer from spilling outside or getting mixed into other developing units when a plurality of developing units are combined into a unit and the process unit is inserted into and removed from the main body of the apparatus. Another object of the present invention is to provide a color image forming apparatus which facilitates jam handling when a conveyance failure occurs in the conveyed recording paper.

Another object of the present invention is to reduce the size of a color image forming apparatus using a process of forming a composite toner image such as a color toner image made of toners of multiple colors on the surface of a photoreceptor drum and transferring the same to recording paper at once. In addition, in order to make it more compact, image forming means such as multiple developing devices and cleaning means are concentrated around the photoreceptor drum, and in particular, the image forming means provided at the periphery of the photoreceptor drum is not aligned with the vertical axis of the photoreceptor drum. It is an object of the present invention to provide a color image forming apparatus which is arranged so that the left and right weight balance is maintained, and has excellent operability such that a process unit can be easily inserted and removed from the apparatus main body.

[Means for solving problems]

The above purpose is to form a plurality of toner images on a rotating image forming body by repeating charging, image exposure and development multiple times on the image forming body, and transfer the toner images to recording paper. In a color image forming apparatus for transferring images, a process unit is configured by integrating an image forming body, a group of developing devices distributed to the left and right with respect to the center line of the image forming body and provided below, and a cleaning device. This is achieved by a color image forming apparatus that is capable of being attached to and detached from the main body.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 to 5.

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

The printer has a clamshell structure divided into an upper casing l containing a transfer belt and an apparatus main body 2 containing a process unit, and the upper casing l is fixed at a predetermined angle by a hinge connected to the apparatus main body 2. can be held open,
In the closed state, it is integrated with the main body 2 of the device by means of a metal fitting.

An image forming body 30 constituting an image forming section of the printer, developing units 36, 37, 38, 39 containing yellow, magenta, cyan, and black developers, and a cleaning device 40 having a pressure releasing mechanism for the image forming body. And charger 35
Each of the equipment is housed in a unitized process cartridge 3 and is removably inserted into the apparatus main body 2 via a pair of guide members 4 that engage on the left and right outer surfaces of the unit. However, in particular, in the present invention, the developing units 36, 37, 38, and 39 are disposed below the image forming member 30 and arranged vertically and sequentially in parallel from the rotational upstream direction so as to face the circumferential surface of the image forming member 30.

That is, the process cartridge 3 is inserted and mounted in the depth direction of the apparatus main body 2 by holding the handle provided on the front side and the guide member 4 is engaged, and when pulled out toward the front, the engagement of the guide member 4 is released and the process cartridge 3 is attached to the apparatus main body. However, since each developing unit is kept with its opening facing upward, there is no possibility of the developer leaking out and falling or getting mixed into other developing units. nothing happens.

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 apparatus main body 2. We have set up
The image forming body 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 carried out as follows.

First, the formation of a multicolor image in this embodiment is performed according to the image forming system shown in FIG. That is, the data obtained from the color image data input unit (FIG. 4 (a)) in which an image sensor scans the original image is input to the image data processing unit (
Image data is created through arithmetic processing in FIG. 4 (b)), and is stored in the star image memory (FIG. 4 (c)). Next, the image memory is taken out during recording and transferred to the recording section (fourth
For example, the color image forming apparatus shown in FIG. 1 is input as shown in 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 B, the laser writing system unit B outputs a laser beam generated by a semiconductor laser (not shown). 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 image forming body 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 scans the circumferential surface of the image forming body 30. Therefore, a latent image corresponding to the first color is formed on the circumferential surface of the image forming body 30 by the main scanning by the laser beam and the sub scanning by the rotation of the image forming body 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 image forming body 30 while being held on the drum surface, and enters the next copy cycle.

That is, the image forming body 30 is charged again by the charger 35, and then outputted from the signal processing section; a second color signal is input to the writing system unit B, and the second color signal is inputted to the above-mentioned first color signal. Writing is performed on the drum surface in the same manner as in the case of the drum surface, and a latent image is formed.

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 sleeve of each of these developing devices 36, 37, 38 and 39, and jumping development is performed using a two-component developer serving as a developing means to form an image with the substrate grounded. body 30
Development is now possible without contact.

The color image thus formed on the circumferential surface of the image forming body 30 is re-charged by the charger 9 and transferred to the recording paper fed from the paper cassette C via the paper feed roller and the paper feed guide in the transfer section 40. is transferred to the bottom surface of the .

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 image forming body 30, and the paper is fed from the paper feed cassette C. The image is transferred to the supplied recording paper via the roller 12 and the timing roller 13 in synchronization with the image formation.

The structure of the transfer belt 50 is such that a 0.5 mm thick elastic layer is provided on the outer periphery of a comb belt containing conductive cloth as a base, and a 50 μm insulating layer (dielectric layer) is further provided on the outer periphery. The transfer belt 50 is stretched between rollers 60a, 60b, and 60c and rotates by driving the roller 60a, and the roller 60b moves up and down, so that the transfer belt 50 comes into contact with or separates from the image forming body 30. The transfer belt 50 is charged by the charging brush 6.
5 or corotron, and the surface of the transfer belt 50 is coated with 1.5xv to 3. Transfer is performed by applying a transfer charge having a polarity opposite to that of the toner of about OKV.

Note that 66 is a cleaning device for the transfer belt that cleans the top of the transfer belt 50.

On the other hand, the blade 40A of the cleaning device 40 comes into contact with the image forming body 30 from which the recording paper has been separated from the drum circumferential surface to remove the remaining toner, and after that, it is separated from the drum circumferential surface again. Entering the process of a new color image format.

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.

FIG. 2 is a front view of the process cartridge 3 taken out from the main body of the apparatus, and the handle 5 on the front side is used to take it out.

In the process cartridge 3, the developing units 36, 37, 38, and 39 are distributed to the left and right with respect to the center line of the image forming body 30, that is, the developing units 36, 36, and 39 are separated from each other by the axis of the image forming body 30. 37 is on the right side, and developer unit 38 and 3
9 are placed at symmetrical positions on the left side, and furthermore, the developing sleeves of the developing units 36 and 37 placed on the right side are arranged clockwise, and the developing units 38 and 3 placed on the left side are arranged in a clockwise direction.
By rotating each of the developing sleeves 9 in a counterclockwise direction, the developing action of each image is performed.

By arranging the developing device group in this manner and further rotating the developing sleeve in the opposite direction, the process cartridge 3 has a well-balanced left and right balance in terms of weight and power transmission, and is easy to handle. The generation of harmful vibrations is also prevented.

In addition, it is possible for the developing units placed in symmetrical positions on the left and right sides to have the same structure, and the toner can be scraped off from the developing sleeve after the developing action is completed extremely efficiently due to the action of gravity. This has the advantage that a suitable amount of fresh toner can always be supplied.

On the other hand, the cleaning device 40 for the image forming body 30
A toner collection box 47 is installed at a symmetrical position to improve the left and right weight balance of the process cartridge 3. A toner transport pipe 49 containing a toner transport screw 48 is installed between the toner collection box 47 and the cleaning device 40 at the front of the process cartridge 3, and the blade 40A
The waste toner peeled off from the surface of the image forming body 30 is transported by the thrust of the toner transport screw 48 and collected into the toner collection box 47.

The toner conveying pipe 49 is a connecting pipe member molded from a synthetic resin material with high lubricity so as not to cause resistance to the operation of the toner conveying screw 48.

Furthermore, the process cartridge 3 has toner replenishment boxes 36A, 37A, and 38 that store toner of a specific color to be supplied to each developer at a position on the front surface corresponding to each developer 36, 37, 38, and 39 housed inside. ^, 39A
It is equipped with

Figure wc3 shows each cross-sectional configuration of the inside of the toner collection box 47 and the connecting portion between the developing device 37 and the toner replenishment box 37A, as viewed from the arrow AA in Figure 2.

The developing device 37 is positioned so as to press against the image forming body 30 with a pair of abutting rollers 3703A provided concentrically at the end of the outer shaft of the developing sleeve 3703, and the extension of the housing 3702 is connected to the toner replenishing box 37A. Connected to the bottom.

The developing device 37 is equipped with a pair of toner conveying screws that agitate the contained toner by using propulsive forces in opposite directions, as will be described later. Toner transport screw 370
7 is extended to the inside of the toner supply box 37A.

Therefore, when the developing sleeve 3703 starts to rotate, the toner conveying screw 3707 rotates via the gear pair G1, and when the toner concentration decreases, the toner supply box 3 rotates via the electromagnetic clutch MC.
The sponge roller 37B included in the sponge roller 37B rotates and drops the stored toner, and the toner is transported into the developing device 37 by the driving force of the toner transport screw 3707.

The toner thus replenished into the developing device 37 is supplied to the upper developing sleeve 3703 where it is evenly mixed with the existing toner by the stirring action of the toner conveying screw 3707 and the other toner conveying screw.

Further, the replenishment of toner from the toner supply boxes 36A8, 38A, and 39A to the developing units 36 and 38, and 39 is performed using the same structure and operation.

Since the toner boxes are arranged in a line substantially parallel to each other, toner can be easily supplied by opening the upper housing 1.

Note that if the aforementioned toner collection box 47 is provided outside the process cartridge 3 and the toner replenishment box 39A is expanded in the rearward direction using that space, a large amount of black toner, which is said to be consumed the most, can be collected in large quantities. Since the toner replenishment box 39A can be stored in the toner replenishment box 39A, the interval between toner replenishment operations for the toner replenishment box 39A can be extended.

Each developing device used in each embodiment contains a developer of a specific color, and its structure and function are the same as the developing device 37 of the printer described below with reference to FIG. be done.

In FIG. 5, 3702 is a housing, 3703 is a developing sleeve, 3704 is a magnet roller, and 3705 is a rigid and magnetic thin layer forming member that regulates the amount of developer, and the thin layer forming member 3705 is a developing sleeve. 370
3, it is pressed with a constant load without the presence of developer. 37078 and 3708 have a screw structure,
A pair of toner conveying screws 3709 that convey and circulate the developer in mutually opposite directions are supply rollers.

The toner supplied from the toner supply box 37A is transferred to one of the toner transport screws 370, which rotates in the direction of the arrow.
7 and the other toner conveying screw 3708 that rotates in the opposite direction so as to overlap with each other, supply roller 3709 as the upper developer that is sufficiently stirred and mixed with the carrier.
is sent to the developing sleeve 3703 via.

The toner conveying screw 3707 and the toner conveying screw 3708 are members that also serve as stirring members that rotate in opposite directions.
The toner and carrier transported to the back side by the thrust of 8 are transferred to the toner transport screw 3707 side and transported to the front side of the drawing by the thrust, and the toner and carrier are homogeneously charged by friction due to the mixing action of the toner and carrier during that time. The developer is formed into a layer and adheres to the circumferential surface of the developing sleeve 3703 by a sponge-like supply roller 3709 that rotates in the direction of the arrow.

In this embodiment, a fixed magnet roller 37o4 and a developing sleeve 3 rotating in the direction of the arrow (clockwise) on the outside thereof
This thin layer of developer adhered on the circumferential surface of the image forming body 3 rotates in the direction of the arrow in the development area 3712.
The latent image on the roller 3703A is developed in a non-contact manner by abutting the latent image on the roller 3703A, thereby forming a toner image.

During this non-contact development, a developing bias containing an AC component is applied to the developing sleeve 3703 from a power source (not shown), and only the toner in the developer is selectively transferred to the surface of the latent image on the image forming sleeve 3703. attached.

After the toner component is consumed, the developer has a high carrier ratio, is transported by the developing sleeve 3703, is peeled off and collected by the scraper 371O, and is again mixed with a developer having a high toner ratio.

〔Effect of the invention〕

The present invention utilizes a process cartridge that houses major process equipment such as an image forming body, multiple developing devices, and a cleaning device in a color image forming apparatus, while efficiently utilizing space while maintaining weight distribution and power system balance. This makes it easy to handle and allows for compact unitization.Furthermore, by providing a toner replenishment device for each developing device on the front of the process cartridge, it is easy to perform various maintenance and toner replenishment management. A color image forming apparatus has been provided that allows maintenance work to be performed extremely easily.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus of the present invention, FIGS. 2 and 3 are a front view and a sectional view of a main part of a process cartridge housed in the apparatus, and FIG. 4 is a block diagram showing an image forming system. FIG. 5 is a sectional view of a developing device housed in the process cartridge. 3... Process cartridge 4... Guide member 5... Handle 30... Image forming body 36.37.38.39... Developing device 3δA, 37A, 38A, 39A... Toner supply box 37B ...Sponge roller 40...Cleaning device 40A...Cleaning blade 47...Toner collection box 48.3707.3708...Toner conveyance screw 49...Toner conveyance pipe 3702...Housing 3703...・Developing sleeve Figure 4 Outer Konica Co., Ltd. (A) (B) (C) (D)

Claims (3)

[Claims] (1) A rotating image forming body; charging, image exposure, and development are repeated multiple times on the image forming body to form a plurality of toner images on the image forming body, and the toner images are transferred to recording paper. In a color image forming apparatus, an image forming body, a group of developing devices distributed to the left and right with respect to the center line of the image forming body and provided below, and a cleaning device are integrated to form a process unit, and the process unit is A color image forming apparatus characterized in that it can be attached to and detached from the image forming apparatus. (2) The color image forming apparatus according to claim 1, wherein each toner supply box is integrally provided in parallel with the developing device group. (3) The color image forming apparatus according to claim 1, wherein in the left and right developing devices, the rotation directions of developing sleeves provided in the left and right developing devices are opposite to each other.