JPH0561342A - Color image forming device - Google Patents

Abstract

PURPOSE:To miniaturize the device, to prevent soiling by toner of an electrifying device, a transferring device and a laser writing system, and to record a good color image as well as a monochrome image. CONSTITUTION:Each developing devices 8, 9, 10, and 11 are provided containing each color developer below a photosensitive belt 1 wound and hung on each rotating roll 2 and 3. An electrifying device 6 and a transferring device 12 are provided faced to a curved surface of the photosensitive belt 1 wound around the rotating roll 3, a cleaning device 13 is provided adjacent to a developing device 8 and faced to the curved surface of the photosensitive belt on the rotating roll 2 side on the opposite side, and each of them are isolated. The electrifying device 6 and the transferring device 12 are shared or attached integrally to an integral member and the position can be changed over. Then, the stretched photosensitive belt 1, cleaning device 13 and each developing device 8, 9, 10, and 11 are made into cartridges and attached freely attachable/ detachable to the color image forming device. Furthermore, each developing device of the color cartridge is shared and utilized even in the monochrome image formation, and black toner is filled to each developing device 8, 9, 10 and 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus in which a toner image is formed on a belt-shaped image forming body by an electrophotographic method and is transferred onto a transfer material to obtain an image.
In particular, it relates to the formation of a mono black image.

[0002]

2. Description of the Related Art A conventional color image forming apparatus having an image carrier belt suspended substantially horizontally and a plurality of developing devices arranged in parallel on the lower surface of the belt is disclosed in, for example, Japanese Patent Laid-Open No. 61-151560. Described and known. According to the color image forming apparatus described in the above publication, the image carrier belt is arranged substantially horizontally and horizontally, and a plurality of developing devices are arranged in parallel on the lower surface of the belt with the development openings thereof facing upward. .. And
Around the image carrier belt stretched between two rotating rollers provided opposite to each other, an exposing section by a charger and a laser writing system, and yellow and magenta arranged at the above-described positions in the order of image formation. , A developing device for accommodating each of the cyan and black developers, and a transfer device provided at a predetermined interval so as to face the curved surface of the image carrier belt wound around one rotating roller. A fixing device is provided above the transfer device. A cleaning device is provided adjacent to the charging device, facing the curved surface of the image carrier belt wound around the other rotating roller and having a predetermined distance.

The color image forming apparatus having the above-described structure records color images one after another on recording paper that is intermittently conveyed. Further, a monochrome image using only black toner requested by the user is also recorded.

[0004]

By the way, in a practical color printer or color copying machine, the toner remaining on the belt surface of the image carrier after the toner image is transferred onto the recording paper is removed by a cleaning device. However, as the number of cleanings increases, the toner scattered from the cleaning device gradually contaminates the surfaces of the charging device, the lens and the mirror of the laser writing system adjacent to the cleaning device, and the toner is formed on the image carrier belt or the recording paper. The image quality of the toner image is adversely affected.

Further, even in a color image forming apparatus, many users request image recording in black, and it is necessary to prevent the adverse effect of image deterioration due to toner scattering, as described above. The present invention solves such problems and prevents toner stains on the charging device, the optical system in the laser writing system unit, and the like, and forms a good color toner image even when forming a mono black image. The goal is to provide equipment.

[0006]

[Means for Solving the Problems] The purpose is to:
This can be achieved by either means (b) or (c).

(A) In a color image forming apparatus in which a color cartridge of a developing device containing a plurality of specific color toners and a monochrome cartridge containing a black toner in a plurality of developing devices replaceable with the color cartridge can be mounted,
A color image forming apparatus, wherein the toner in a specific developing device is sequentially consumed during image formation using the monochrome cartridge.

In (b) and (a), the order of consumption of black toner accommodated in a plurality of developing devices is such that the developing device closer to the cleaning device is used first, and the charging device and the developing device closer to the exposing portion are used later. A color image forming apparatus characterized by the above.

(C) A color image forming apparatus characterized in that the developing device in which trouble has occurred in (a) is stopped and switched to another developing device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a side sectional view showing the construction of a color image forming apparatus of FIG. 1, a block diagram showing an image forming system of FIG. 2, and a construction of a charging device and a transfer device of FIG. Will be described with reference to FIG. 4, a block diagram showing the operation of the charging device and the transfer device in FIG. 4, and a side sectional view showing the configuration of the color image forming apparatus including the black toner developing device in FIG.

However, the present invention is not limited to this embodiment.

In FIG. 1, reference numeral 1 denotes a flexible photosensitive belt which is a belt-shaped image forming body. The photosensitive belt 1 is provided between rotating rollers 2 and 3 and is driven by the rotating roller 2. It is conveyed counterclockwise as indicated by the arrow.

Reference numeral 4 denotes a guide member fixed to the main body of the apparatus so as to be inscribed in the photoconductor belt 1. The photoconductor belt 1 is stretched by the action of the tension roller 5 so that its inner peripheral surface is The guide member 4 is rubbed. The guide member 4 is provided with a concave portion in an area unnecessary for image formation to reduce resistance due to rubbing. Of course, this recess may be omitted if the rubbing resistance is low. Further, a low friction member such as a Teflon coating is provided on either surface of the photoconductor belt 1 or the guide member 4 for the purpose of reducing the sliding resistance between the photoconductor belt 1 or the guide member 4, or is constituted by the above low friction member. Preferably.

Therefore, the photoconductor on the outer peripheral surface of the photoconductor belt 1 is always kept in a constant relation position with respect to the surface of the guide member 4 even during conveyance, so that a stable image forming surface can be formed. ..

Further, by disposing the developing device and the cleaning device below the photosensitive belt, it is possible to prevent the developer from scattering and spilling.

Reference numeral 6 denotes a scorotron charger, which is a charging means, and 7
Is a laser writing system unit as an image exposing means, 8 to 11
Is a developing device that is a plurality of developing means that contains a developer of a specific color, and these image forming means are arranged at positions facing the guide member 4 of the photosensitive belt 1. Then, in order to hold the gap without hindering the movement of the photoconductor belt 1, the guide member 4 is brought into contact with the gap holding means on the outer side of the photoconductor belt 1.

In addition to the optical system shown in the figure, the laser writing system unit 7 may be an optical system in which a light emitting section and a converging optical transmission body are integrated.

The developing units 8, 9, 10, and 11 contain, for example, yellow, magenta, cyan, and black developers, respectively, and the developing sleeves 8A and 9A that maintain a predetermined gap with the photosensitive belt 1. , 10A, 11A, and has a function of visualizing the latent image on the photoconductor belt 1 by a non-contact developing method. Unlike the contact development, the non-contact development has an advantage that the movement of the photosensitive belt 1 is not hindered. The developing device 11 has a capacity 1.5 to 2.0 times larger than that of the other developing devices 8, 9 and 10 in order to support monochrome image recording requested by the user.

A transfer device 12 is provided above the charging device 6 and slides up and down integrally with the charging device 6 to switch the position. 12A is a static eliminator, 13 is a cleaning device, and 13A is a blade of the cleaning device and 13 is a toner conveying roller.
B is kept at a position separated from the surface of the photosensitive belt 1 during image formation and is pressed against the surface of the photosensitive belt 1 as shown in the figure only during cleaning after image transfer.

A color image forming process by the color image forming apparatus 25 is performed as follows.

First, the formation of a multicolor image according to this embodiment is shown in FIG.
Image forming system. That is, the data obtained by the color image data input unit (FIG. 2A) in which the image sensor scans the original image is processed by the image data processing unit (FIG. 2B) to create image data, This is once stored in the image memory (FIG. 2C). Then, the image memory is taken out at the time of recording and is recorded (see FIG. 2).
(D)), for example, is input to the color image forming apparatus 25 shown in the embodiment of FIG.

That is, when a color signal output from an image reading apparatus separate from the printer is input to the laser writing system unit 7, the laser writing system unit 7 generates a semiconductor laser (not shown). The laser beam is rotationally scanned by the polygon mirror 7B rotated by the drive motor 7A, the optical path is bent by the mirrors 7D and 7E via the fθ lens 7C, and the photoconductor belt previously charged by the charger 6 as a charging means. 1 is projected onto the peripheral surface to form a bright line.

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

That is, the photoconductor belt 1 has the charger 6
Then, the second color signal output from the signal processing unit is input to the writing system unit 7, and writing on the belt surface is performed in the same manner as in the case of the first color signal described above. The image is formed. The latent image is subjected to reversal development in a non-contact state by the developing device 9 loaded with magenta (M) toner as the second color.

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

Reference numeral 10 denotes a developing device having cyan (C) toner, which forms a cyan (C) NATO image on the surface of the belt based on a control signal generated by a signal processing section.

Further, reference numeral 11 denotes a developing device having black toner, which is formed by superposing a black toner image on the belt surface by the same process. These developing devices 8, 9, 10 and
A direct current or an alternating current bias is applied to each sleeve of 11, and jumping development is performed by a one-component or two-component developer that is a developing device, and the development is performed in a non-contact manner on the photoreceptor belt 1 whose base is grounded. It is supposed to be done.

Thus, the color toner image formed on the peripheral surface of the photoconductor belt 1 is slid downward and switched to the position of the charger 6, the transfer device 12 and the neutralizing plate.
At 12A, the image is transferred onto the transfer material sent from the paper feed cassette 14 through the paper feed guide 15.

That is, the transfer material contained in the paper feed cassette 14 is carried out by the rotation of the paper feed roller 16 and one of the uppermost layers is carried out, and the timing is adjusted with the image formation on the photosensitive belt 1 via the timing roller 17. And is supplied to the transfer device 12.

The transfer material subjected to image transfer and charge removal is more reliable than the photosensitive belt 1 which suddenly changes its direction along the rotating roller 2 without being affected by the charge removal effect on the image quality such as toner scattering. And then move it upwards to the fixing roller.
The image is fused by 18 and then discharged onto a tray 20 via a discharge roller 19.

On the other hand, in the cleaning device 13, the photosensitive belt 1 which has been transferred to the transfer material is further conveyed and the blade 13A facing the rotating roller 3 and the rotating toner conveying roller 13B are brought into pressure contact with each other. After the residual toner is removed and after the completion of the removal, the blade 13A is separated again, and a little later, the toner carrying roller 13B is separated, and a new image forming process is started.

The charging device 6 and the transfer device 12 are shown in FIGS. 3 and 4.
An example of switching between and will be described below.

An integral member 60 for integrally holding the transfer device 12 having the charge eliminating plate 12A and the charger 6 is always provided, for example, by a spring 32 having one end fixed to a part of the frame of the color image forming apparatus 25 as shown in FIG. It is pulled downward and is positioned and locked by a stopper 6C.

As shown in the block diagram of FIG. 4, when the image forming sequence is started by the start of copying from an operation unit (not shown), a solenoid 30 located above the transfer unit 12 shown in FIG. 3 is energized through a control unit. Signal sent solenoid
When 30 is turned on, the integrated member 60 holding the transfer device 12 and the charger 6 is pulled upward through the arm 61 that engages the solenoid plunger 31 against the tension of the spring 32. Then, the integral member 60 moves along an engaging groove (not shown) which is appropriately engaged with the slide portion 62 and the fixed guide 63, so that the charger 6 is spaced a predetermined distance from the curved portion at the right end of the photosensitive belt 1. Is pulled up to the opposite position.

By the processes described above, the toner of a predetermined color is formed on the photosensitive belt 1, and the start signal of the transfer material (timing roller drive) is held by the timing roller 17 in order to set the paper feed registration timing at the timing of starting the transfer. Signal), the drive signal from the control unit is received and the energization of the solenoid 30 is cut off. Then, the integral member 60 slides downward through the slide portion 62 and the fixed guide 63 by the tension of the spring 32, returns to the position of the stopper 6C, and the transfer process (transfer, separation) is performed between the transfer device 12 and the charge eliminating plate 12A. It has been switched to the state and is functioning.

Even if the positions of the transfer device 12 and the charging device 6 are attached to the integral member 60 contrary to the above-mentioned example, it goes without saying that the mode of switching is included in the present invention.

Although not shown, the charging device 6 and the transfer device 12
It is also possible to switch the output from the same power source so as to output 4 kv and 0.25 mA when the scorotron charging is charged to the photosensitive belt 1 and output 5 kv and 2-3 mA during the transfer. The space is reduced and the color image forming apparatus 25 can be made compact. The cleaning device 13 is disposed to face the curved surface at the left end of the photoconductor belt 1 wound around the rotating roller 2 with a predetermined interval, and the waste toner box 13C.
Is connected below the cleaning device 13.

Then, the cleaning device 13 and the waste toner box 13C are formed into a cartridge together with the developing devices 8, 9, 10, 11 and the stretched photosensitive belt 1 as shown by a chain line to form a color image forming device 25. It is designed to be detachably attached.

Further, at least the photoconductor belt 1 and the cleaning device 13 and / or the waste toner box 13C are made into a cartridge, and the developing devices 8, 9, 10 and 11 are made into a cartridge, and each of them is placed in the color image forming apparatus 25. It may be attached.

Therefore, the charging device 6, the transfer device 12 and the charge eliminating plate 12A
The cleaning device 13 and the cleaning device 13 are provided in the color image forming device 25 even if toner is scattered from the cleaning device by the cartridges which are separately provided at both longitudinal ends of the photoconductor belt 1 and whose outer periphery is formed in a hermetically sealed state. Since the diffusion is extremely small, the charging device 6, the transfer device 12, and the optical systems 7A, 7B, 7C, 7D, 7 of the laser writing system unit
A stable color image is formed even when the color image forming apparatus 25 is operated for a long time without being contaminated by toner such as E.

Then, as shown in FIG. 5, the developing devices 8, 9
Black toner is filled in each of 10 and 11. That is, a developing device cartridge for color toner and a developing device cartridge for mono-black toner are commonly used, and for example, the developing devices 8, 9,
10 is filled with 2000 copies of A4 size toner to form black toner developing devices 8 ', 9', and 10 ', and the same size is used for the conventional large-capacity developing device 11 containing black toner. Fill 3000 copies of black toner.

The arrangement of the developing devices 8 ', 9', 10 'and 11 with respect to the photosensitive belt 1 which rotates in the direction of the arrow is the same as in the case of forming the color image as shown in the figure. The developing device 11 is positioned adjacent to the cleaning device 13 which is arranged in the above order, and the developing devices 10 ', 9'and 8'are sequentially arranged on the right side thereof. The developing units 8 ', 9', 10 ', 11 are used in the order of development, which is the farthest position from the charger 6 or the exposure unit of the laser writing system unit 7 shown in the figure.
When the black toner in the developing device 11 is consumed, it is automatically switched to the adjacent developing device 10 ', and then the developing devices 9'and 8'are used in this order.

This switching is performed by the CPU stored in advance.
It operates properly under the control of. Depending on the frequency of use of the black toner, the developing device 11 alone or the developing device 11 or 10 'may be filled and used. In any case, it is preferable that the developing devices 8'and 9'close to the charging device 6 are not used as much as possible.

Further, if, for example, if the developing device 11 fails during development during image formation and development becomes impossible, the image can be immediately switched to the adjacent developing device 10 'under the control of the CPU stored in advance. It does not interfere with the formation. The photosensitive member used in the color image forming apparatus 25 is not limited to the belt-shaped photosensitive member and may be a drum-shaped photosensitive member.

Since the monochrome developing device cartridge thus configured is used in common with the color developing device cartridge, it is not necessary to make a special monochrome developing device cartridge, which is extremely economical. is there. Further, it is possible to sufficiently cope with monochrome image recording which is frequently requested by the user, and since the developing device 11 which is most isolated from the charging device 6 and the laser writing system unit 7 is used in sequence, charging is performed. It is possible to prevent contamination of each optical system in the container 6 and the laser writing system unit 7. Further, as in the case of forming a color image, at least the photoconductor belt 1, the cleaning device 13, and the waste toner box 13C can be formed into a cartridge in a sealed state as shown by a chain line as in the previous embodiment. Toner scattering is prevented and the optical systems 7A, 7B, 7C, 7D and 7E of the laser writing system unit 7 are kept clean.

[0046]

The cleaning device of the present invention, the waste toner box, the charging device, and the transfer device are separated from each other, and the toner belt is scattered and diffused in the image forming apparatus by using the photosensitive belt, the cleaning device, and the developing device as a cartridge. Since it was remarkably prevented, it was possible to prevent toner contamination of the charging device, the transfer device, and each optical system in the laser writing system.

Further, since the charging device and the transfer device can be used in common or can be connected to each other so that the photosensitive belt can be switched to a predetermined position, the image forming apparatus can be downsized. Also,
Even when frequently forming monochrome images, use a monochrome developer cartridge that is the same as the color developer, and prioritize the use order of the developer that is farther than the charger or the exposure part of the laser writing system. Therefore, the toner stain on the charging device and the laser writing system unit can be prevented as much as or more than when the color image is formed.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the configuration of a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an imaging system according to one embodiment of the present invention.

FIG. 3 is a side view showing a configuration of a charging device and a transfer device according to an embodiment of the present invention.

FIG. 4 is a block diagram showing the operation of a charging device and a transfer device according to an embodiment of the present invention.

FIG. 5 is a side sectional view showing a configuration of a color image forming apparatus including a black toner developing device according to an embodiment of the present invention.

[Explanation of symbols]

 1 photoconductor belt (image forming belt) 2 rotary roller 3 rotary roller 6 charger 7 laser writing system unit 8 developing device (yellow) 8'developing device (black) 9 developing device (magenta) 9'developing device ( Black) 10 Developing device (cyan) 10 'Developing device (black) 11 Developing device (black) 12 Transfer device 12A Discharging plate 13 Cleaning device 13C Waste toner box 18 Fixing roller 25 Color image forming device 30 Solenoid 60 Integrated member

Claims (3)

[Claims] 1. A color image forming apparatus in which a color cartridge of a developing device containing a plurality of specific color toners and a monochrome cartridge containing a black toner in a plurality of developing devices replaceable with the color cartridge can be mounted. A color image forming apparatus characterized in that toner is sequentially consumed from a specific developing device when forming an image using a monochrome cartridge. 2. The consumption order of black toner accommodated in a plurality of developing devices according to claim 1, the developing device closer to the cleaning device is used first, and the developing device closer to the charging unit and the exposing unit are used later. And a color image forming apparatus. 3. A color image forming apparatus according to claim 1, wherein the developing device having the trouble is stopped from use and switched to another developing device.