JPH0311369A - Color image forming device - Google Patents

Abstract

PURPOSE:To facilitate an operation and to perform stable copying for a long time by constituting a process cartridge which includes a developing device group and a cleaning device, etc., and can be freely attached to and detached from a device main body and using a discharged toner collecting device also as a black toner replenishing device. CONSTITUTION:An image carrier drum 30, the developing devices 36-39 storing the developers of yellow, magenta, cyanogen and black, a cleaning device 40, an electrostatic charger 35, a pretransfer electrostatic charger 9 and a toner collecting box 70 being the discharged toner collecting device are housed in one process cartridge 3 to become a unit. The toner collecting box 70 is such constituted that it can be also used as the black toner replenishing device for the developing device 39 of black toner. Therefore, the large toner collecting box 70 is not needed and it is unnecessary to replenish the black toner frequently. Thus, the stable copying is performed for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention involves uniformly charging an image bearing drum and performing image exposure based on an image signal corresponding to a specific color to form a latent image. The step of developing the latent image using a developing device containing toner of a color corresponding to the image signal is repeated for a preset number of colors to form a colored toner image on the image carrier drum. The present invention relates to an improvement in a color image forming apparatus that forms a fixed color image by transferring it to a transfer material.

[Background of the invention]

In an electrophotographic image forming apparatus that forms a color image such as a full color image or a functional color image, a charger that charges an image bearing drum, an image exposure means that exposes an image to the image bearing drum, and a A developing device that develops an electrostatic image with toner, a transfer device that transfers the toner image on the image carrier drum to a transfer material, and the like are arranged around the image carrier drum.

Among these, the developing units in full-color electrophotographic image forming apparatuses are composed of three or four developing units each containing yellow (Y), magenta (M), cyan (C) toner, and sometimes black (BK) toner. Consists of a developing device,
While the image carrier drum rotates three or four times, yellow (Y), magenta (M), cyan (C), and sometimes black (BK) toner images are formed on the image carrier drum,
This toner image is transferred to a transfer material, and the transferred transfer material is fixed to obtain a full-color image. When using this 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 and patent application No. 62-320
The color image forming apparatus described in the specification of No. 596 is a proposal in which the image bearing drum and the developing device are integrated into a unit, which contributes to improving the maintainability. It was easy to cause breakage and contamination.

Further, in a color image forming apparatus that uses a transfer drum to transfer each color toner image to a transfer material, an example in which the image bearing drum and its surroundings are formed into a unit is described in Japanese Patent Laid-Open No. 58-72159.

In this way, various color image forming methods have been developed for copying color images, each with its own special color, but each method requires the image bearing drum, developing device, cleaning device, etc. as described above. By storing it in one cartridge and making it into a unit, it is possible to simplify its handling, jam handling, and other maintenance work.

On the other hand, looking at the layout of each of the above-mentioned equipment in a unitized cartridge, the developing unit group is arranged at the bottom of the image carrier drum, and the image transfer section is placed at the top of the image carrier drum. An image forming apparatus configured as shown in FIG. Such an image forming apparatus was previously proposed by the present applicant in, for example, Japanese Patent Application No. 6 dated April 3, 1999.

With this type of device, the image is transferred to the lower surface of the transfer material, so there is less risk of it being smudged by falling toner, and a high-quality image can be provided. It is also possible to open the door, which has the advantage of further improving the workability of jam removal and maintenance.

[Problem to be solved by the invention]

By the way, in the color m image forming apparatus as described above,
When multicolor toner images are superimposed and transferred onto an image carrier drum, residual toner tends to occur more easily than when monochrome images are formed.

This means that a large amount of toner is collected during cleaning, which poses the problem of requiring a large waste toner collection device.

Furthermore, in full-color image formation, there has been a problem in that black toner consumes the most amount according to conventional experience, and black toner must be replenished frequently.

The present invention solves the above-mentioned drawbacks, and provides a color image forming apparatus that does not require a large waste toner collection device, does not require frequent replenishment of black toner, and therefore enables stable copying over a long period of time. The purpose is to provide.

[Means to solve the problem]

The above purpose is to provide a charger, a color toner developer, and a black toner developer to the image carrier drum and its surroundings. In the color image forming apparatus, the color image forming apparatus includes a developing device group consisting of a developing device, a cleaning device, and a waste toner recovery device for recovering waste toner collected by the cleaning device, the image bearing drum, a developing device disposed below the drum. The present invention is characterized in that a process cartridge is configured that includes a group of devices and a cleaning device and can be freely inserted into and removed from the main body of the device, and the waste toner recovery device is configured to be able to be used also as a device for replenishing black toner to the black toner developing device. This is achieved by a color image forming device that uses

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a color image forming apparatus that is an embodiment of the present invention, FIG. 2 is a sectional view showing the image bearing drum and toner collection box of FIG. 1, and FIG. 3 is an image forming system. FIG. 1 is a block diagram of a printer to which the present invention is applied.

The printer has a clamshell structure divided into an upper housing 1 and an apparatus main body 2.

The upper housing 1 can be held at a predetermined open angle using a hinge IA connected to the device main body 2 as a fulcrum, and is integrated with the device main body 2 by a stopper (not shown) in the closed state.

Image carrier drum 3 constituting the image forming section of the printer
Developing device 36, 37, 38° 39 which is a developing means containing 0, yellow, magenta, cyan, and black developers, a cleaning device 40 which is a cleaning means, a charging device 35, a pre-transfer charging device 9, and waste toner. Each component of the toner collection box 70, which is a collection device, is housed in the process cartridge 3 of the body to form a unit, and can be inserted into and removed from the inside of the device main body 2 via a guide member 4 provided on the bottom surface. In particular, in this embodiment, the housings of the respective developing units 36, 37, 38, and 39 are integrally constructed, and the rotating direction is such that the housings are arranged below the image carrier drum 30 and facing the circumferential surface thereof. They are arranged in parallel upwards along the .

That is, the process cartridge 3 is inserted and installed in the execution direction of the apparatus main body 2 by holding the handle provided on the front side and engaging the guide member 4, and when pulled out toward the front, the engagement of the guide member 4 is released. The developing units 36, 37 and 38.3 are removed from the front of the apparatus main body 2.
9 are maintained with their openings facing upward, so that 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 transfer material conveying surface in a part above the process cartridge 3 that spans both the upper housing 1 and the apparatus main body 2. The image carrier drum 30 receives laser scanning from the laser writing system unit B from diagonally below, and transfers a color toner image formed overlappingly on its circumferential surface to the lower surface of the transfer material. method.

In this way, the transfer material is conveyed horizontally over the top of the process cartridge 3, and since the transfer surface faces downward, even if the toner spills or scatters from the cleaning device 40 or the like, the image surface It does not go to the extent of contaminating the product.

In addition, this device has the following advantages: (1) The paper feeding system is located below, and the center of gravity is set further below, which has great advantages in terms of the structure of the machine.

(2) The transport system can be easily opened when a jam occurs.

Benefits include:

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 the image data processing unit (Figure 3 (b)) equipped with a calculation function to create image data, which is then stored in the - star image memory (Figure 3 (c)). ). Then, the image memory is taken out during recording and inputted into a printer, which is a recording section (FIG. 3(d)), for example, 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 B, the laser writing system unit B receives a laser beam generated by a semiconductor laser (not shown). The beam is rotated and scanned by a polygon mirror 32 rotated by a drive motor 31, passes through an fθ lens 33, and then passes through three mirrors 3.
The optical path is bent by 4A, 34B, and 34C, and the light is projected onto the circumferential surface of the image carrier drum 30 to which a charge has been previously applied by a charger 35 serving as a charging means.

On the other hand, when scanning is started, the laser beam is detected by the index sensor, modulation of the laser beam by the first color signal is started, and the modulated laser beam scans the circumferential surface of the image carrier drum 30. . Therefore, a latent image of the first color is formed on the circumferential surface of the image carrier drum 30 by main scanning by the laser beam and sub-scanning by the rotation of the image carrier drum 30. This latent image is developed by a developing device 36 loaded with yellow toner in the developing means, and a toner image is formed on the circumferential surface of the image bearing drum 30. The obtained toner image, while being held on the circumferential surface of the image carrier drum 30, passes under a cleaning device 40, which is a cleaning means, which is separated from the circumferential surface of the image carrier drum 30, and enters the next copy cycle.

That is, the image carrier drum 30 is charged again by the charge l135, and then the second
The color signal is input to the writing system unit B, and the image carrier drum 3
Writing is performed on the zero circumferential surface and a latent image is formed. The latent image is produced by developer 3 loaded with magenta toner as the color '$2.
7. This magenta toner image is formed over the previously formed yellow toner image.

A developing device 38 has cyan toner, and forms a cyan toner image on the circumferential surface of the image carrier drum 30 based on an image signal generated by a signal processing section.

Furthermore, 39 is a developing device having black toner, and forms a black toner image superimposed on the circumferential surface of the image carrier drum 30 by the same process. Each of these developing devices 36, 37
．． Direct current or even alternating current bias is applied to each of the sleeves 38 and 39, so that non-contact jumping development is performed using a two-component developer serving as a developing means.

The color image thus formed on the circumferential surface of the image carrier drum 30 is transferred to the lower surface of the transfer material fed from the paper feed cassette C via the paper feed roller 12 and the paper feed guide in the transfer section.

That is, after this multicolor toner image is charged by the pre-transfer charger 9 to be easily transferred, the transfer belt 50 used as a transfer means, which has been rotated since before the start of transfer, is brought into contact with the image carrier drum 30. , is transferred onto a transfer material supplied from a paper feed cassette C via a paper feed roller 12 and a timing roller 13 in synchronization with image formation.

The transfer belt 50 is stretched between a roller 59 and a roller 60, and the image carrier drum 30 is rotated by the rotation of the roller 60.
The roller 58 is rotated in synchronization with the circumferential speed of the image carrier drum 30, and as the roller 58 moves up and down, it is moved away from or in contact with the image carrier drum 30.

The roller 58 is attached to a lever 57 that can swing around the axis of the roller 60 as a fulcrum.
The transfer belt 50 is held in the upper position shown by the solid line by an elastic member that urges the image forming member 30, but the transfer belt 50 is held in the upper position shown by the solid line by the power of a solenoid or the like that operates at the timing of transfer, that is, the transfer belt 50 is moved to the lower position shown by the dashed line, that is, around the circumference of the image forming body 30. It is moved to the position where it is pressed against the surface.

As the transfer belt 50, a rubber belt containing conductive cloth is used as a base, and a high resistance layer made of an elastic material and an insulating layer with a thickness of 0.5 mm are provided on the outside of the belt.

The transfer belt 50 is charged by a transfer device 51, and a transfer charge having a polarity opposite to that of the toner is applied to perform the transfer. Note that the toner adhering to the transfer belt 50 is removed and cleaned by a transfer belt cleaning device 50A.

The transfer material to which the multicolor toner image has been transferred in this way is an image forming body 3.
The toner is separated from the sheet and conveyed to the fixing section, where the toner is melted and fixed by a fixing roller 80 that rotates at a speed suitable for the transfer material and color mode, and then discharged from the machine via a discharge roller 90.

On the other hand, the image carrier 30 from which the transfer material has been separated is cleaned by rubbing and removing residual toner by a cleaning device [40] having a plate-shaped blade 41 made of hard urethane rubber or the like. When the cleaning is completed, the cleaning device 40 is again separated from the circumferential surface of the image carrier drum 30, and a new color image forming process begins.

The waste toner, which is the residual toner removed by the cleaning device 40, passes through a toner transport pipe 71 installed on the front surface of the process cartridge 3, and is transferred to a toner recovery box 70, which also serves as a toner supply box for the developing device 39 attached to the process cartridge 3. It will be collected.

The toner conveying pipe 71 has a built-in flexible toner conveying screw 72 that is rotated by the power system of the apparatus main body 2, and waste toner is transferred from the cleaning device 40 to the toner collection box 70 by the propulsive force generated by the rotation of the toner conveying screw 72. transported.

Note that the toner conveying pipe 71 is a pipe member molded from a synthetic resin material with high lubricity so as not to provide resistance to the operation of the toner conveying screw 72.

When the process cartridge 3 is installed in the apparatus main body 2, an electrical connection terminal provided on the outer side of the process cartridge 3 in the rear direction, a rotating shaft of the photoreceptor drum 30 protruding from the side, and the developing unit 36 to A rotating shaft for transmitting power to 39 and the like is connected to a connection terminal and a power shaft provided in the main body 2 of the device.

As shown in FIGS. 1 and 2, the toner collection box 70 also serves as a toner supply box for the developing device 39 that stores black toner. Also, the toner collection box 70
may be connected to a toner replenishment box for replenishing new toner, and may be in the form of a box in which new toner and waste toner can be mixed.

The developing device 39 is positioned so as to press against the image carrier drum 30 with a pair of abutting rollers 3903A provided concentrically at both shaft ends of the developing sleeve 3903, so that the surface of the developing sleeve 3903 and the surface of the image carrier drum 30 are pressed against each other. and are located at regular intervals.

The abutting roller 3903A is connected to the developing sleeve 3903.
is provided to maintain a constant distance from the circumferential surface of the image carrier drum 30 and to perform non-contact development.

An extension of the housing 3902 of the developer 39 is connected to the bottom of the toner collection box 70 .

The developing device 39 is equipped with a pair of developer conveying screws 3907 and 3908 that stir the developer contained in the developing device 39 by using propulsive forces in opposite directions, as will be described later. One developer conveying screw 3907 having a propulsive force in the direction is extended into the toner collection box 70 which also serves as the toner supply box.

Therefore, when the developing sleeve 3903 starts rotating, the gear pair G
A developer conveying screw 3907 rotates through the developer device 39, and a toner concentration detection means for detecting the toner ratio in the developer is provided in the developing device 39. When the toner concentration falls below a certain set ratio, , a toner supply roller 39 using a sponge roller or the like provided at the bottom of the toner collection box 70 by a tooth-arashi pair G2 via an electromagnetic clutch MC that is activated when the toner concentration decreases under the control of the main body control section.
B rotates and drops the collected and stored toner. The fallen toner is transported into the developing device 39 by the propulsive force of the developer transporting screw 3907.

The transported toner is replenished by a developer transport screw 3907 rotating in one direction and another developer transport screw 3908 rotating in the opposite direction. It is supplied to the developing sleeve 3903 by a supply roller.

The waste toner collected by the cleaning device 40 is a mixture of color and black toners, but from past experience and experiments, even if the waste toner is recycled to the black developing device 39, there is almost no change in the black image. It has been confirmed that this is not acceptable. Therefore, no problem occurs even if the waste toner is used as replenishment toner for the black developing device 39, which consumes a large amount.

〔Effect of the invention〕

According to the present invention, as described above, in a color image forming apparatus having a cleaning device and a waste toner collecting device for collecting waste toner collected by the cleaning device, an image bearing drum is disposed below the drum. A process cartridge is constructed which includes a group of developing devices and a cleaning device that can be freely inserted into and removed from the main body of the device, and the waste toner collecting device can also be used as a device for replenishing black toner to the black toner developing device. Therefore, there is no need for a large waste toner collection device, and there is no need to frequently replenish black toner, which consumes a large amount.In addition to being easy to operate, it is possible to make stable copies over long periods of time. A color image forming apparatus is now provided.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a color image forming apparatus that is an embodiment of the present invention, FIG. 2 is a sectional view showing the image bearing drum and toner collection box of FIG. 1, and FIG. 3 is an image forming system. FIG. ■...Upper housing IA...Hinge 2...Device main body 3...Process cartridge 4...Guide member 9...Pre-transfer charger 30
...Image carrier drum 36.37.38.39...
・Developing device 39B...Sponge roller 2 40...Cleaning device 50...Transfer bell) 51...
・Transfer device 70...Toner collection box 71...Toner transport tube 72.3907.3908...Developer transport screw 80...Fixing roller (A) (B) (C) (D)

Claims (1)

[Claims] A color image having an image bearing drum, a charging device, a developing device group consisting of a color toner developing device and a black toner developing device, a cleaning device, and a waste toner collecting device for collecting waste toner collected by the cleaning device around the image bearing drum. In the forming apparatus, a process cartridge including the image bearing drum, a group of developing devices disposed below the drum, and a cleaning device constitutes a process cartridge that can be inserted into and removed from the apparatus main body, and the waste toner collection device is connected to the black A color image forming apparatus characterized in that it is configured so that it can be used also as a black toner replenishing device for a toner developing device.