JPH031165A - Color image forming device - Google Patents

Abstract

PURPOSE:To make the device compact and to stably supply black-and-white images which are in great demand by employing a black-and-white process cartridge, specifying the array and costitution of an image forming machine and arranging a color developing device on a main device side. CONSTITUTION:A process cartridge 1 contains an electrifier 3, a BK developing device 8 and a cleaning device 10 integrally around an image carrier drum 2 and is mounted on the device main body detachably, and a color developing device 4 is arranged on the device main body side. In this case, a developing device group which includes a color developing device 4 and a BK developing device 8 is arranged below an image carrier drum 2 and a transfer conveying means 40 for transfer paper is arranged above the drum. Consequently, the device can be made compact and black-and-white images which are in great demand can stably be supplied.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a color image forming apparatus such as a color printer or a color copying machine, and particularly relates to a color image forming apparatus that enables a stable supply of black and white images, which are in high demand. Regarding equipment.

[Conventional technology]

Conventionally, for example, Japanese Patent Application Laid-Open No. 57-163276 discloses a copying machine having a process cartridge that integrally houses an image carrier drum, a charger, a cleaning device, and a black and white developer, and is configured to be freely inserted into and removed from the main body of the device. ing.

In such a copying machine, the cartridge is replaced within the usage limit of the image forming equipment and materials, avoiding excessive use of the copying machine, and always ensuring stable image quality.

On the other hand, in the copying industry, there is an increasing demand for color images with a larger amount of information in place of black and white images.

Therefore, Japanese Patent Application Laid-Open No. 58-72159 discloses a color process cartridge containing an image bearing drum, a charger, a color developing device consisting of a plurality of developing devices, a cleaning device, etc., and a black (BK) process cartridge as a spare for the cartridge. ) A color copying machine is described that has a black and white process cartridge containing a developing device.

However, since a plurality of developing devices are incorporated in the color process cartridge, the color process cartridge becomes complicated and expensive. Therefore, we will add practicality in terms of cost to color process cartridges! Therefore, it is preferable to replace or discard the cartridge after, for example, continuing image formation until the use of the carrier in the image bearing drum or developer, which has a long life, is reached. The lifespan of the image carrier drum is usually 5 to 8 years.
The lifetime of the carrier in the developer is said to be 20,000 to 30,000 color copies, so during that time, toner is continuously replenished from a toner replenishing device installed in the main body of the apparatus and corresponding to each of the plurality of developing devices. It becomes necessary to do this.

This toner replenishing device is located on the outer wall of the process cartridge and is removably connected to the process cartridge at a connecting portion having a toner replenishing opening to the developing chamber of each developing device.

[Problem that the invention seeks to solve]

However, the toner replenishing device is attached and detached from the connecting portion each time the process cartridge is inserted and removed, but at that time, there is a problem in that the cartridge and the main body of the device are contaminated due to toner leakage and scattering. Further, in order to eliminate this problem, a complicated device is required, such as providing an opening shielding member at the connecting portion that opens and closes each time the toner replenishing device is attached to and removed from the process cartridge. In particular, in color image forming apparatuses, it is necessary to supply toners of each color to multiple developing units, which makes the layering device complicated, and even if a small amount of toner leaks or scatters, the image quality deteriorates due to mixing of toners of each color. cause problems.

Furthermore, in the color image forming apparatus described in Japanese Patent Application Laid-open No. 58-72159, when forming an image, it is necessary to replace the cartridge with a dedicated cartridge every time the image is changed from color to black and white, or from black and white to color. This method has drawbacks such as being complicated, expensive, and time-consuming.

In addition, since the multiple developing devices in the process cartridge are horizontal and adjacent to each other and stacked in the lateral direction of the image bearing drum, the toners of each color are likely to mix, making the device unstable. It had Further, since the transfer paper transfer means is disposed below the image bearing drum, it has the disadvantage that it is easily contaminated by toner leakage and scattering.

[Means for solving problems]

(Object of the Invention) The present invention has been proposed in view of the above-mentioned circumstances, and aims to stabilize the quality of black and white images by adopting a black and white process cartridge, and to improve image quality by optimizing the arrangement and configuration of image forming equipment. An object of the present invention is to provide a color image forming device which improves the image quality and makes the device more compact, and which has a color developing device located on the device main body side and which makes it possible to convert from black and white to color without being restricted by cartridges. .

(Structure and operation of the invention) The above object is to provide an image bearing drum, a developing device group including a charging device, a color toner developing device, and a black toner developing device, a cleaning device, and a transfer paper transfer means on the periphery thereof. In the color image forming apparatus, the black toner developer;
A process cartridge is formed which integrally includes an image bearing drum and a cleaning device and is removably inserted into the apparatus main body, and the color developing device is arranged on the apparatus main body side, and the developing device downwards,
This is achieved by a color image forming apparatus characterized in that the transfer conveyance means is disposed above.

In the color image forming apparatus of the present invention, an image bearing drum, a charger, a BK developer, a cleaning device, and if necessary a waste toner collection container are integrally housed in a process cartridge, and the cartridge is a main body of the apparatus. The main feature of the apparatus is that the color developing units for yellow (Y), magenta (M), and cyan (C) are arranged on the side of the main body of the apparatus. With this configuration, it is possible to realize a low-cost black and white process cartridge that can be used disposablely as needed.Also, a color developer is provided as an option, and black and white process cartridges can be created with one touch without the need to replace the cartridge. It is possible to convert images from color to black and white.

In addition, since the color developing device is installed in the main body of the device, it is possible to replace the developing device as needed, regardless of the cartridge, and there are other advantages such as easy installation of a toner supply device to the color developing device. occurs.

Furthermore, in the color image forming apparatus of the present invention, the developing device group including the color developing device and the BK developing device is arranged below the image carrier drum, and the transfer paper transfer means is arranged above. It is characterized by its stabilization and compactness as well as improved quality of black and white and color images.

The group of developing devices is vertically arranged so as to surround the outer periphery of the image carrier drum, and in particular, the Y, M, and C color developing devices have an integrated unit structure, sharing a part of the wall surface with each other. It is preferable to do so. The developer used in the developer group may be a one-component developer containing magnetic toner as a main component or a two-component developer containing non-magnetic toner and a magnetic carrier.

However, the two-component developer is preferred in order to obtain a clear color tone of the colorant contained in the toner.

The BK developing device in the process cartridge is provided with a toner chamber for replenishment, and the cartridge is replaced when the toner in the toner chamber is consumed, or a toner replenishing device is attached to the developing device, and the toner is filled with the toner by the device. Toner is continuously replenished until the usage limit of the carrier is reached, and the cartridge is replaced when the usage limit of the carrier is reached.

In some cases, the BK developing device in the cartridge may be replaceable, and the cartridge may be replaced when the use limit of the image bearing drum is reached.

In addition, in order to efficiently control the formation of black and white images, which are in high demand, it is preferable to provide a waste toner collection container in the cartridge, and use a cleaning device to scrape and collect the residual toner on the surface of the image bearing drum. The obtained waste toner is preferably collected into the collection container by a waste toner transport pipe having, for example, a screw conveyor or a spring coil.

Furthermore, the waste toner may be collected in the cavity of the image carrier drum instead of the waste toner collection container.

Further, it is preferable that the Y, M, and C color developing device groups are replenished with toner from, for example, a toner replenishment hopper provided on the front or rear surface of the apparatus main body, and depending on toner consumption or carrier fatigue. They may be used individually or as a unit by replacing them at any time.

Next, when forming an image using the color image forming apparatus of the present invention, black and white and color image forming processes are stored in the program memory in advance, and one of the processes is selected by operating a program operation key provided on the main body of the apparatus. is selected and the desired image forming process is performed via the control device.

〔Example〕

FIG. 1 is a sectional view of a color printer explaining this embodiment. In the figure, 1 is a process cartridge, and inside the cartridge there is a photoreceptor drum 2, a charger 3, a BK developer 8,
Cleaning device 10. A waste toner collection container 15 is included. In the BK developing device 8, a developing roll 8a,
[Agitator roll 8b.

8c, a layer thickness regulating roll 8d, a developer layer scraping member (scraper) 8e after development, and a toner replenishment cylinder 8f, and by continuous toner replenishment from the toner replenishment cylinder, a large amount of black and white images can be produced. Stable supply is possible.

The cleaning device 10 includes a waste toner collection tube 10a.

Waste toner collection film fob, cleaning blade l
Oc, has a pre-cleaning static elimination lamp lod,
The waste toner scraped off by the blade lOc is collected in the collection tube 10a via the waste toner collection film tab.

The collection pipe 10a is a waste toner transport pipe 1 installed at the front of the device.
2, and the other end is connected to a waste toner collection container I5.
The cleaned waste toner is connected to the collection pipe 15a of
will be collected.

The charger 3 is a scorotron charger having a grid, and the discharge wire can be cleaned by manual cleaning means. Next, the color developing device 4 includes a Y developing device 5 and an M developing device 6.
, C developing device 7 share a part of the wall surface with each other to form an integral unit, and are detachably installed in the main body of the apparatus. Each developing device C1 includes a developing roll 5a, 6a, 7a
, It stirring crawl 5b6b, 7b+5e, 6c, 7c,
It has layer thickness regulating rolls 5 d , 6 d , 7 d and scrapers 5 e , 6 e , 7 e. This color developing unit 4 is not limited by the process cartridge 1, and can be used by replacing the unit as required by the user. In this embodiment, each of the Y, M, and C developing units is provided with a hopper for replenishing toner of the corresponding color, and the usage limit ratio of the carrier in the developer is adjusted so that color images can be continuously formed. It's Nishide.

In addition, the BK developer unit 8 and the color developer unit 1
The developing roll and stirring roll are arranged vertically, and the stirring and mixing efficiency of the developer is excellent, and it is said that it is possible to impart sufficient triboelectric charge to the developer.

Further, the developing device group is arranged below the photosensitive drum 2 so as to surround the circumferential surface of the photosensitive drum 2, so that the two devices can be combined more compactly.

Next, 20 is a laser optical device for image exposure, which includes a polygon mirror 20a1, a collimating lens 20b1, reflection mirrors 20c, 20d, 20e, an Xf-theta lens 20f1, and a dustproof glass 20g, and L is image exposure light. Semiconductor laser light modulated by an external video signal is introduced into the optical device 20, and the device 20 also irradiates image exposure light onto the photoreceptor drum to form an electrostatic latent image.

30 is a paper feed cassette, and the transfer paper P fed from the horn set 30 by a paper feed roll 31 is transported to a transfer area via a transport path 32 and upper and lower rolls 33a and 33b of a transport roll 33.

40 is a transfer conveyance device, 40a is a transfer conveyance belt, 40
b and 40c are drive rollers for the belt 40a, 40d is a belt tension roll, and 40e is a transfer pole. 41
is a fixing device consisting of a pressure roll 41a and a heat roll 41b, and the transfer paper after fixing is discharged to a paper discharge tray 43 by lower rolls 42a and 42b of a delivery roll 42.

The main body of the apparatus is the upper roll 33a of the transfer paper transport roll 33.
, transfer conveyance device 140. , the pressure roll 4 of the fixing device 41
1a, the upper casing containing the upper roll 42a of the delivery roll 42 and the lower casing containing the process cartridge are opened with P and -P as boundaries, 5 to prevent jams occurring in the transfer/conveyance system. processing is possible.

Insertion and removal of the paper feed cassette 30 is accomplished by opening the side cover containing the paper discharge tray 43 via the boundary P3-P. Further, jam removal during the transfer paper conveyance process is performed by opening the side lid including one side of the conveyance path with ps-ps as the boundary.

Next, a method for inserting and removing the process cartridge 1 and the color developing unit 4 into and from the lower housing of the main body of the apparatus will be explained with reference to FIG. 1 and the second factor. First, from the lower housing to the cartridge 1 and unit 4.
To take out the process cartridge 1, first open the lower casing and the upper casing upwards about the axis Ql, and then first remove the process cartridge 1 from the handles M provided on its front and rear surfaces.
, M' are grasped and pulled upward to be taken out. Next, the color developing unit 4 located below the no-notridge 1 is similarly pulled upward and taken out.

On the other hand, in order to install the cartridge 1 and the color developer unit 4 into the lower housing Kl, first the color developer unit 4 is attached to the unit receivers 4a and 4 provided in the lower housing 1.
b, and then the cartridge l is dropped into la +lb provided in the lower housing. Next, the upper casing 2 and the lower casing are closed to enable image formation. When the upper housing 2 is closed, the protrusion N (N') provided on the cartridge 1 is pushed downward by the protrusion L (L') provided on the upper housing 2,
The ridge holder is tightly fixed to the members 1a and 1b. Incidentally, a gap between the photosensitive drum 2 and the color developing unit 4 is secured by an abutting member (not shown), and when the upper housing is closed, the cartridge 1 is held together with the cartridge 1 via the abutting member. The color developer unit also has a unit holder member 4a;
4b.

Next, in the color printer having the above configuration, image formation was performed as follows. Process specification key 47 in advance
The color process specification key 48 is operated to read out the color process stored in the memory 45, and the CPLI4
6, a color process is specified, and based on the color video signal related to the color process, the Y, M, and C color developers of the color developer unit 4 disposed on the main body side of the apparatus and the BK developer in the process cartridge are designated. Image formation was performed using

First, during the first rotation of the photoreceptor drum 2 with the cleaning device released, a charge of -700V is applied to the drum 2 by the charger 3, and then the semiconductor The laser beam oscillated from the laser device 22 is modulated, and the obtained modulated laser beam is imagewise exposed onto the drum 2 via the laser optical device 20 including the polygon mirror 20a to form an electrostatic latent image, Contains a two-component developer, with a DC component of 160
Y developer unit 5 in color developer unit 4 to which a developing bias of 500 V and an AC component of 3 KHz at 0 V is applied.
The image was developed in a non-contact, reversal manner, and a Y toner image was formed on the photoreceptor drum.

The photoreceptor drum 2 is then rotated and charged by the charger 3 at 170
After being recharged to 0 V, image exposure with a laser beam modulated by the M signal and similar development using the M developing device 6 were performed to form an M toner image superimposed on the Y toner image. Similarly, during the third and fourth rotations of the photosensitive drum 2, image exposure by laser light modulated by the C signal and the BK multiplied signal, and reversal development by the C developer 7 and the BK developer 8 in the process cartridge 1 are repeated. Then, a C toner image and a BK toner image were sequentially superimposed on the Y toner image and M toner image to obtain a color toner image.

The M toner image, the C toner image, and the BK toner image were formed under the same image forming conditions as the Y toner image.

Next, according to a predetermined image forming program, the transfer paper is sent out from the paper feed cassette 30 by the paper feed roller 31, and is conveyed to the transfer area T by the conveyance roller 338 and the transfer belt 40a via the conveyance path 32. The transfer area T
The color toner image on the photoreceptor drum 2 is transferred onto the transfer paper by the transfer pole 40e, and is heated and fixed by the heat roll 41b of the fixing device t41, and the color toner image is transferred face down to the transfer paper by the paper discharge roll 42. after the transfer, the cleaning device is turned “on”;
The remaining toner on the photoreceptor drum 2 was cleaned and prepared for the next image formation. A color image was formed by continuously repeating the above cycle 1000 times. During this time, the color toner is supplied to the toner replenishing hoppers 5e (Y) and 6e (M
), 7e (C), and BK) toner was continuously replenished from the toner replenishment cylinder 8f while image formation was performed, resulting in a high-density, clear color image being obtained from beginning to end.

Next, the monochrome (black) process specification key 49 of the process specification keys 47 was operated to change the image forming process to a monochrome image forming process, and image formation was performed using the BK developer 8 based on the monochrome video signal. .

With the cleaning blade lOc turned on, a charge of -700V is applied to the photoreceptor drum 2 by the charger 3, and then the laser beam oscillated from the laser device 22 is modulated by the BK video signal. The modulated laser beam was imagewise exposed onto the drum 2 through the laser optical device 20 to form an electrostatic latent image. This electrostatic latent image is developed in a non-contact, reversal manner by a BK developer 8 which contains a two-component developer, has a DC component of 1600V and an AC component of 3KHz, and is applied with a bias of 500V. A BKI-toner image was formed on drum 2.

This BK) toner image was transferred and fixed onto a transfer paper fed from the paper feed cassette 30 to form both B and K images, and the photosensitive drum 2 after the transfer was cleaned by the cleaning device IO. At the time when image formation has been performed 25,000 times while receiving toner supply from the toner supply cylinder 8f,
Taking carrier fatigue into account, the process cartridge was replaced, a new cartridge was installed, and subsequent image formation was performed, resulting in a high-density, clear black-and-white image.

Furthermore, in this embodiment, by collecting the waste toner scraped off by the cleaning device tlO into the collection container 15, image formation over a long period of time is possible.

Although a color printer was used in the above embodiment, it can be combined with a color scanner to form a color copying machine, and this case is also included in the present invention.

[Effects of the Invention] As is clear from the above description, the color image forming apparatus of the present invention achieves compactness of the apparatus and stable arrangement of each image forming device, and moreover, switching between color and monochrome images is not limited by the cartridge. This can be achieved with a single touch without having to be affected by the process, and it has the advantage of being able to stably supply black and white images, which are particularly in high demand, and also being able to supply color images as an option.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating the structure of a color printer according to an embodiment, and FIG. 2 is a perspective view of the color printer shown in FIG. l...Process cartridge 4...Color developer unit 5.6.7...Y, M, C developing units 8...BK developer 10...Cleaning device 15...Waste toner Recovery device 20... Laser optical device 30...
・Paper feed cassette 40...Transfer conveyance means 45...Memory 46...CPU 47...Process key

Claims (1)

[Claims] A color image forming apparatus having an image bearing drum, a developing device group including a charging device, a color toner developing device, and a black toner developing device, a cleaning device, and a transfer paper transfer means on the periphery of the image bearing drum, the black toner developing device, the image forming device; A process cartridge is formed which integrally includes a carrier drum and a cleaning device and is removably inserted into the apparatus main body, and the color developing device is disposed on the apparatus main body side, and the developing device is disposed with respect to the image carrier drum. A color image forming apparatus characterized in that the group is arranged below and the transfer conveyance means is arranged above.