JPH0561307A - Color image forming device - Google Patents

Abstract

PURPOSE:To miniaturize a color image forming device, to prevent an electrifier, a transfer device and a laser writing system from being stained with toner and to always record a satisfactory toner image. CONSTITUTION:On the downward of a photosensitive belt 1 wound around turning rollers 2 and 3 and stretched therebetween, developing units 8, 9, 10 and 11 storing their respective color developers are provided. The electrifier 6 and the transfer device 12 are provided opposed to the curved surface of the photosensitive belt 1 wound around the turning roller 3. A cleaning device 13 is adjacent to the developing unit 13 and is provided opposed to the curved surface of the photosensitive belt on the side of the opposite turning roller 2. They are separated from one another. The electrifier 6 and the transfer device 12 are shared or their positions are switched by integrally attaching the devices 6 and 7 to an integral member. The stretched photosensitive belt 1, cleaning device 13 and developing units 8, 9, 10 and 11 are made in the forms of cartridges and attachably/detachably fitted in the color image forming device. At the time of forming a color image, the photosensitive belt 1 is turned five times; at the time of forming a monochrome image, it is turned two times. Then, transfer is finished.

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.

[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, black developer, 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.

[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.

If the charging device and the transfer device are separately arranged at both ends in the longitudinal direction of the stretched image carrier belt, a required space is required for each of them, so that the image forming apparatus is inevitably large in size. Turn into.

The present invention solves such a problem and prevents the charging device, the laser writing optical system, and the like from being contaminated due to toner scattering and enables miniaturization, and always records a good toner image. An object of the present invention is to provide a color image forming apparatus that can be used.

[0007]

[Means for Solving the Problems]
b is achieved by any means.

(A) In a color image forming apparatus in which a stretched belt-shaped image forming body and a plurality of developing devices are arranged in parallel therebelow, a cleaning unit is provided adjacent to the developing device. A color image forming apparatus, wherein the image forming body and the plurality of developing devices can be integrally attached to and detached from the image forming apparatus.

(B) In (a), the image forming body rotates 5 times during color image formation by the image forming process of at least charging, exposure, development, transfer, and cleaning, and the image forming body during the mono black image formation by the above process rotates 5 times. The color image forming apparatus is characterized in that the image forming body rotates twice.

[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 transfer device and a charging device of FIG. 4, a block diagram showing the operation of the charging device and the transfer device of FIG. 4, a diagram showing the number of rotations of the image forming body at the time of forming the color and mono black images, and a developing device of FIG. Will be described with reference to a side sectional view showing the configuration of the color image forming apparatus positioned above.

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.

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, the color signal output from the image reading device separate from the printer is the laser writing system unit 7.
Is input to the laser writing system unit 7, the laser beam generated by the semiconductor laser (not shown) is rotationally scanned by the polygon mirror 7B rotated by the drive motor 7A, and passes through the fθ lens 7C and the mirror 7D. The optical path is bent by 7E, and a bright line is formed by being projected onto the peripheral surface of the photosensitive belt 1 to which electric charges have been previously given by the charger 6 as a charging means.

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 yellow (Y) in the developing means.
The toner image is formed on the surface of the belt by reversal development in a non-contact state by the developing device 8 loaded with the toner (visual medium). 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) toner image on the belt surface 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.

As described above, the number of rotations of the photosensitive belt 1 at the time of forming a color image by at least the processes of charging, exposing, developing, transferring, and cleaning is as shown in the solid line in FIG. The electrostatic latent image formed on the surface of the photosensitive belt 1 by the scorotron charging and exposure is developed with yellow toner.

Next, during two rotations, charging, exposure and development with magenta toner are similarly performed, and during three rotations, cyan, 4
During rotation, each black toner is applied and developed. Therefore, a color image of yellow, magenta, cyan, and black toners is formed on the surface of the photosensitive belt 4 by four rotations. Then, in order to stably and satisfactorily transfer the color image formed on the photoconductor belt 1 to the transfer material, the photoconductor belt 1 further rotates once while carrying the toner image which has been completely developed. The toner image is transferred onto the surface of the transfer material by the transfer device 12 switched to the position shown in FIG. 1, and then the photosensitive belt 1 is cleaned by the cleaning device 13. That is, the photosensitive belt 1 is charged for the first time,
Five rotations are required from exposure and development to the end of cleaning. Therefore, since the developing process is completed at the time of transfer, stable transfer of the toner image is performed, and, for example, when a thick paper or OHP sheet is used as the condition of the transfer material, or when the mono-black image is formed, the photoreceptor belt 1 is used.
There is an effect that efficient image processing can be performed by appropriately changing the rotation speed, the fixing condition or the transfer condition. In addition, the number of rotations of the photosensitive belt 1 at the time of forming a mono black image is shown in FIG.
As indicated by the dotted line, the black toner is applied to the electrostatic latent image on the surface of the photosensitive belt 1 that has been charged and exposed at the first rotation to develop the electrostatic latent image.

Then, similarly to the case of the color image described above, the photosensitive belt 1 makes one rotation while carrying the toner image, and then the toner image is transferred onto the transfer material by the transfer device 12 at the position shown in FIG. Processing is performed.

That is, by rotating the photosensitive belt 1 twice during the formation of a mono black image, the same effect as that during the formation of the color image can be obtained.

Next, an example of switching between the charging device 6 and the transfer device 12 will be described below with reference to FIGS. 3 and 4.

An integral member 60 for integrally holding the transfer device 12 having the charge eliminating plate 12A and the charger 6 is constantly provided, for example, in FIG. 3 by a spring 32 whose one end is fixed to a part of the frame of the color image forming apparatus 25. 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 the operation unit (not shown), the solenoid 30 located above the transfer unit 12 shown in FIG. 3 is energized through the 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, and the charger 6 is spaced a predetermined distance from the curved portion at the right end of the belt photosensitive member 1. Is pulled up to the opposite position.

The toner of a predetermined color is formed on the belt photosensitive member 1 by each of the above-described processes, and the transfer material start signal (timing roller drive 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 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 photoreceptor belt 1 as shown by a chain line, and then the color image forming device 25 is formed. 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, the static eliminator 12A and the cleaning device 13 are provisionally provided as a cleaning device by means of cartridges which are arranged separately at both longitudinal ends of the photosensitive belt 1 and whose outer periphery is hermetically sealed. Even if the toner is scattered from 13, it hardly diffuses into the color image forming apparatus 25. Therefore, the charging device 6, the transfer device 12, and the optical systems 7A, 7B, 7C, 7D of the laser writing system unit 7,
A stable color image is formed even when the color image forming apparatus 25 is operated for a long time without contamination by toner such as 7E.

Further, the charging device 6 and the transfer device 12 are commonly used, or both are integrally connected so that the charging device 6 and the transfer device 12 can be slid up and down to be switched to a predetermined position on the photosensitive belt 1 as required for image formation. The color image forming apparatus 25 can be downsized. In the above-described embodiment, the color image forming apparatus 25 in which the developing devices 8, 9, 10, and 11 are located below the photosensitive belt 1 has been described, but as shown in FIG. The case where 10 and 11 are located above will be described below.

That is, yellow, magenta, cyan, and black developers, for example, are accommodated in this order from the right side of the drawing above the photosensitive belt 1 which is stretched around the rotating rollers 2 and 3 and rotates counterclockwise. Each of the developing devices 8, 9, 10, 11 has a predetermined interval and is provided with the same function as in the case of being located below.

The cleaning device 13 is disposed adjacent to the developing device 11 located at the left end, faces the curved surface of the photosensitive belt 1 wound around the rotating roller 2 with a predetermined space, and is discarded. The toner box 13C is connected below the cleaning device 13.

On the other hand, the charging device 6, the transfer device 12 and the static eliminator 12A
Is configured in the same manner as described in the above-mentioned embodiment, and is provided at a predetermined interval so as to face the curved surface of the photosensitive belt 1 on the side opposite to the cleaning device 13. Then, the photosensitive belt 1, the cleaning device 13, and the developing devices 8, 9, 1
0 and 11 are formed into a cartridge as shown by a chain line and are detachably attached to the color image forming apparatus 25.

In this cartridge formation, the cartridges of the developing devices 8, 9, 10, and 11 and the cartridge of the photosensitive belt 1, the cleaning device 13, and the waste toner box 13C are separately configured as described above. May be.
Although not shown and described, the laser writing system unit 7, the paper feed cassette 14, the paper feed guide 15, and the paper feed roller.
The paper feed / conveyance system including the timing rollers 17 and the paper discharge rollers 19 and the like are provided in substantially the same arrangement as in the above-described embodiment, and have the same functions.

The image forming processes of charging, exposure and development, transfer and cleaning which are carried out in synchronism with the rotation of the photosensitive belt 1 are carried out in the respective developing units 8, 9, 10, 11 described above.
Is exactly the same as when is located below. The number of rotations of the photosensitive belt 1 at the time of forming a color image is 5 as in the case shown in FIG. 5, and the rotational speed of the photosensitive belt 1 at the time of forming a mono black image is 2 as shown by the dotted line in FIG. Is set to. Therefore, the same effects as those of the above-described embodiment can be obtained, and since the developing devices 8, 9, 10, 11 are located above, the toner replenishing device can be constructed with an extremely simple structure.

Color image forming apparatus constructed as described above
As for 25, the cleaning device 13 is arranged adjacent to the developing device 11 and the cleaning device 13 is arranged in the same manner as in the above-described embodiment in which the developing devices 8, 9, 10, 11 are arranged below the photosensitive belt 1.
Since the charging device 6, the transfer device 12, and the charge removing plate 12A are sufficiently isolated from each other, it is possible to prevent the charging device 6 and the transfer device 12 from being contaminated by toner.

Further, at least the photoconductor belt 1, the cleaning device 13 and the waste toner box 13C can be made into a cartridge in a sealed state as shown by the chain line as in the previous embodiment, so that the toner in the color image forming apparatus 25 can be formed. Of the laser writing system unit 7 is prevented and the optical systems 7A, 7B, 7 of the laser writing system unit 7 are prevented.
C, 7D and 7E are kept clean.

[0053]

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 are commonly used or both are connected to each other so that the photosensitive belt can be switched to a predetermined position, it is possible to downsize the image forming apparatus and efficiently produce a good toner. Images are now recorded.

[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 showing the image forming system of the above.

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.

FIG. 5 is a diagram showing the number of rotations of the photoconductor belt at the time of forming a color image and a mono black image according to the embodiment of the present invention.

FIG. 6 is a side sectional view showing the configuration of a color image forming apparatus in which a developing device according to an embodiment of the present invention is located above.

[Explanation of symbols]

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

Claims (2)

[Claims] 1. A color image forming apparatus comprising a stretched belt-shaped image forming body and a plurality of developing devices arranged in parallel therebelow, wherein a cleaning unit is arranged adjacent to the developing device and A color image forming apparatus, wherein the image forming body and the plurality of developing devices can be integrally attached to and detached from the image forming apparatus. 2. The method according to claim 1, wherein at least charging, exposure,
A color image forming apparatus characterized in that the image forming body is rotated 5 times during color image formation by the image forming process of development, transfer and cleaning, and the image forming body is rotated twice during mono black image formation by the process. ..