JPH11231743A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the pressing force of an entire spring for pressing a squeeze roller to a backup roller, to lighten a load imposed on a belt photoreceptor and to make a housing of a color image forming device light in weight by making the pressing force of the spring successively larger in the disposing order of developing devices. SOLUTION: A PS spring 9 (a yellow PS spring, a magenta PS spring, a cyan PS spring and a black PS spring are generically named as the PS spring 9) keeps press-contact force between a squeeze roller 7 and a belt photoreceptor 3 constant by pussing up bearing parts at the both ends of the roller 7. By changing the pressing force of the PS spring 9, adhesive ink is removed and the filming performance of a picture is adjusted. The large and small strength relation of the press-contact force of the respective PS springs that are yellow, magenta, cyan and black ones is set to yellow < magenta < cyan < black in the disposing order of the developing devices.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing device for an electrophotographic image forming apparatus, and more particularly to a developing device for a color image forming apparatus.

[0002]

2. Description of the Related Art An electrophotographic type color image forming apparatus needs to be equipped with developing devices of three primary colors of yellow, magenta and cyan and four colors of black, so that the size of the entire image forming apparatus can be reduced. It is difficult to reduce the weight.

[0003] Factors hindering the reduction in size and weight include:
The large weight is due to the need to increase the rigidity of the housing to support a large load and the large size of the motor for driving the developing device. The large size of the motor also causes high manufacturing costs.

[0004]

As described above, the conventional color image forming apparatus has a problem that it is difficult to reduce the size and weight of the entire apparatus.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional color image forming apparatus, and to reduce the load, which is one of the causes of the problems, in the developing apparatus of the color image forming apparatus. Is to provide.

[0006]

SUMMARY OF THE INVENTION A developing device according to the present invention is a color image forming apparatus for sequentially forming images of respective colors of yellow, magenta, cyan and black in a predetermined order on a belt photosensitive member circulating. A developing device for developing the yellow, magenta, cyan, and black, respectively, a developing roller that supplies ink to a latent image formed on the belt photoreceptor by a corresponding laser device to develop the latent image; A developer supply unit that supplies ink to the developing roller, and removes the ink attached to a portion other than the latent image of the belt photoconductor provided downstream of the developing roller and develops the developed image. A squeeze roller that is dried to form a film and a backup roller that is provided on the opposite side of the belt photoconductor are provided. Wherein a spring for pressing the squeeze roller, and a cleaning roller for cleaning the developing roller, the pressing force of the spring Te,
The first developing device to the fourth developing device are sequentially increased in the order of development. In particular, the pressing force of the spring is 3 to 9 kgf for the first developing device, and 6 to 12 kgf for the second developing device.
f, the third developing device is 9 to 15 kgf, the fourth developing device is 12 to 18 kgf, and the first developing device, the second developing device, the third developing device, and the fourth developing device increase in this order. It was done. Further, the first developing device is a yellow developing device, the second developing device is a magenta developing device, the third developing device is a cyan developing device, the fourth developing device is a black developing device, or the first developing device is a black developing device. Magenta developer,
The second developing device is a yellow developing device, the third developing device is a cyan developing device, or the fourth developing device is a black developing device,
Alternatively, the first developing device is a cyan developing device, the second developing device is a magenta developing device, the third developing device is a yellow developing device, the fourth developing device is a black developing device, and the squeeze roller has elasticity. It is formed of a resin material, particularly urethane.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing device of this embodiment is a developing device for a color image forming apparatus having developing devices of three primary colors of yellow, magenta and cyan and four colors of black. PS for pressing the squeeze rollers provided in the yellow and magenta and cyan and black developing units to the belt photoreceptor in order to remove ink adhering to portions other than the portion where the latent image is formed. The pressing force of a spring (primary squeeze spring: spring) is increased in the order of yellow-magenta-cyan-black, which is the development order, and the sum of the pressing forces of the four PS springs is made smaller than before.

Hereinafter, the present embodiment will be described with reference to the drawings.

FIG. 1 is a sectional view showing details of a developing unit used in the embodiment of FIG. 2, and FIG. 2 is a front view showing an embodiment of the present invention.

In FIG. 2, the belt photoreceptor 3 is wound between a driving roller 29 and a driven roller 30, and is driven by the driving roller 29 to make a circular motion in the direction of arrow A. The belt photoreceptor 3 is provided with a photosensitive layer on a resinous film having a conductive surface, on which a barrier layer for protection and liquid toner (ink) are separated from the belt photoreceptor. And a release layer for facilitation.

A yellow developing unit 12, a magenta developing unit 15, a cyan developing unit 18, and a black developing unit 21 are arranged below the belt photoreceptor 3 below the driving roller 29 and the driven roller 30 in order from the right. The yellow laser device 11, the magenta laser device 14, the cyan laser device 17, and the black laser device 20 are arranged on the right side of each of them.

Above the driving roller 29 and the driven roller 30, the belt photoreceptor 3 is provided with guide rollers 31 and 32.
The transfer roller 26 is disposed opposite the guide roller 32 with the belt photoconductor 3 interposed therebetween. Further, a fixing roller 27 is provided on the transfer roller 26. A main charger 28 is provided at a position facing the guide roller 32.

At the position of the driven roller 30, a drying roller 23 is provided outside the belt photoreceptor 3 with the removal roller 24 in contact with the drying roller 23.

The belt photoreceptor 3 includes a main charger 28
When the laser beam reaches the position of the yellow laser unit 11 after passing through the drive roller 29, the laser beam is radiated by an image signal for attaching and developing a liquid yellow toner (yellow ink). When the toner reaches the position of the yellow developing device 12, yellow ink is supplied to the exposed portion where the latent image is formed and developed.

The image on the belt photoreceptor 3 developed with the yellow ink is pressed against the backup roller 6 by the yellow PS spring 13 in the yellow developing device 12 and adheres to a portion other than the portion where the latent image is formed. The remaining yellow ink is removed, and the yellow ink image is dried to form a film.

The pressing force of the yellow PS spring 13 is:
Since the yellow ink is also pressed in the development of the next magenta, cyan and black colors, it is not necessary to form a complete film when developing the yellow image. Is a low pressing force of 3 to 9 kgf that does not mix the yellow ink with the yellow ink and does not deteriorate the yellow image.

Here, the configuration and operation of the developing device will be described with reference to FIG.

The yellow developing device 12, the magenta developing device 15, the cyan developing device 18, and the black developing device 21
Have the same configuration except for the pressure contact force of each PS spring, and the operation is the same except that the color of the ink is different. Therefore, the configuration and operation of each developing device will be described collectively.

In FIG. 1, a developing roller 4 is formed of a metal material, and a liquid toner (ink) discharged from a developing solution supply unit 2 adheres to a surface of the belt photoreceptor 3.
To develop the latent image formed on the belt photoconductor 3. There is a gap of 0.15 mm in the developing area between the developing roller 4 and the belt photoconductor 3.

A backup roller 5 provided opposite to the developing roller 4 with the belt photoreceptor 3 interposed therebetween is for keeping the gap between the developing roller 4 and the belt photoreceptor 3 constant.

The cleaning roller 1 is for cleaning the developing roller 4 in contact with the developing roller 4, and is made of a coarse foam. Cleaning roller 1
Has a hole in the axial direction (hollow), and the ink of the developing roller 4 is washed away by supplying ink to the hollow part and excreting it from the foam.

The developer supply unit 2 includes a cleaning roller 1
The ink is supplied to the developing roller 4 cleaned by the above.

The squeeze roller 7 provided downstream of the developing roller 4 is formed of an elastic resin material such as urethane and adheres to a portion other than the latent image of the belt photoconductor 3 after being developed by the developing roller 4. The developed toner is removed and the developed image is dried to form a film.

The backup roller 6 has a function of pressing the belt photoreceptor 3 sandwiched between the backup roller 6 and the squeeze roller 7 to convert an image into a film.

When the developing device is performing the developing operation, the tip of the blade 8 is not in contact with the squeeze roller 7, but the developing operation is completed and the developing device is separated from the belt photoreceptor 3. At this time, the tip contacts the squeeze roller 7 to remove the ink adhering to the squeeze roller 7.

The PS spring 9 (yellow PS spring 13, magenta PS spring 16, cyan PS spring 19, and black PS spring 22)
Are collectively referred to as PS springs 9) by pushing up the bearings at both ends of the squeeze roller 7 to maintain a constant pressure contact force between the squeeze roller 7 and the belt photoconductor 3. By changing the pressing force of the PS spring 9, it is possible to adjust the performance of removing adhered ink and forming an image into a film.

The charger 10 is a belt photoconductor 3 immediately after development so that development can be performed continuously.
Is charged.

The developing device constructed as described above operates as follows. That is, the photoconductor 3 which forms a latent image by being irradiated with laser light corresponding to an image of a corresponding color from a laser device provided on the right side of each developing device is turned into a developing roller 4.
Is reached, the developing roller 4 receiving the ink supply from the developer supply unit 2 transfers the ink to the latent image on the photosensitive member 3 while rotating in the same direction as the moving direction of the photosensitive member 3. And develop. At this time, the photosensitive member 3 may adhere to a part other than the part where the latent image is formed, and the developed image is also in a wet state.

When the developed image arrives at the position of the squeeze roller 7 while the photosensitive member 3 is continuously conveyed, the ink adhering to portions other than the image is removed by the squeeze roller 7 pressed by the PS spring 9. At the same time, the developed image is dried to form a film.

Photoreceptor 3 after development and film formation
Is continuously transported and reaches the position of the charger 10, the entire surface is uniformly charged by the charger 10, and is sent to the developing device of the next color.

Returning to FIG. 2, the description of the developing device will be continued.

Subsequently, when the belt photoreceptor 3 is conveyed and reaches the position of the magenta laser unit 14, a laser beam based on an image signal for attaching and developing the magenta ink is emitted and exposed, and the magenta developing unit 15 is exposed. Is reached, the magenta ink is supplied to the exposed area where the latent image is formed and developed, and the magenta PS is developed.
The magenta ink adhered to a portion other than the image by being pressed by the spring 16 is removed, and the magenta ink image is formed into a film together with the yellow ink image.

The pressing force of the magenta PS spring 16 is
Since the magenta ink is also pressed during the subsequent development of each of the cyan and black colors, the ink of each of the cyan and black colors does not mix with the magenta ink and the yellow and magenta images do not degrade.
kgf, the pressure contact force of yellow PS spring 13 is 3 ~
The pressing force is higher than 9 kgf.

Further, the belt photoreceptor 3 has a cyan laser 17
Is reached there, a laser beam is emitted by an image signal for adhering and developing the cyan ink and is exposed, and the cyan ink is supplied to a portion where the exposed and latent image is formed by the cyan developing device 18. Then, the cyan ink adhered to a portion other than the image by being pressed by the cyan PS spring 19 is removed, and the image of the cyan ink is formed into a film together with the image of the yellow ink and the image of the magenta ink.

The pressing force of the cyan PS spring 19 is such that the black ink does not mix with the magenta ink and the yellow, magenta and cyan images do not deteriorate because the cyan ink is also pressed during the next black development. 9 to 15 kgf, which is higher than the pressing force of the magenta PS spring 16.

Finally, when the belt photoreceptor 3 reaches the position of the black laser device 20, a laser beam based on an image signal for depositing and developing black ink is radiated and exposed, and the black developing device 21 exposes the laser beam. The black ink is supplied to the portion where the latent image is formed and developed, and is pressed by the black PS spring 22 to remove the black ink adhering to the portion other than the image. The film is formed together with the ink image, the magenta ink image, and the cyan ink image.

The pressing force of the black PS spring 22 is
Since the development of black ink is the final step of development, it is necessary to perform complete film formation in this step.
At a pressure of up to 18 kgf, the pressing force is higher than the pressing force of the cyan PS spring 19.

Accordingly, the magnitude relationship between the pressing forces of the yellow, magenta, cyan and black PS springs is (yellow) <(magenta) <(cyan) <
(Black).

When the belt photoreceptor 3 carrying the image developed by the four developing devices reaches the position of the drying roller 23 provided opposite the driven roller 30, the drying roller 23 develops the image. The ink is further dried to a film having a drying rate of about 98%. Also, the belt photoconductor 3
The ink adhering to the drying roller 23 from the
4 removes it from the drying roller 23. In this way, the drying roller 23 is prevented from swelling due to the ink transferred from the belt photoreceptor 3 and deteriorating in performance.

When the belt photoreceptor 3 further circulates and reaches the position of the transfer roller 26, the transfer roller 26 transfers the image on the belt photoreceptor 3 to a sheet (conveyed between the transfer roller 26 and the fixing roller 27). (Not shown), and the fixing roller 27 fixes the image on paper.

Thereafter, the belt photoreceptor 3 reaches the position of the main charger 28 again and repeats the above operation.

In the above embodiment, the order of disposing the developing devices is as follows.
Although the order of development is yellow, magenta, cyan, and black, the order of magenta, yellow, cyan, black, and cyan, magenta, and black are set according to the characteristics of the ink so that a color closest to the natural color is obtained.・ The order may be yellow / black or some other order.

[0043]

As described above, the developing device according to the present invention is capable of forming each of the four color images of yellow, magenta, cyan and black in a predetermined order on the belt photosensitive member circulating. The developing device includes a developing roller that supplies ink to the latent image formed on the belt photoreceptor by a corresponding laser device to develop the latent image, a developer supply unit that supplies ink to the developing roller, and a developing roller. A squeeze roller provided downstream to remove ink adhering to portions other than the latent image on the belt photoconductor and to dry the developed image to form a film, and a backup roller provided on the opposite side of the belt photoconductor with the belt interposed therebetween. A spring that presses the squeeze roller and a cleaning roller that cleans the developing roller. By sequentially increasing the arrangement order, it is possible to reduce the pressing force of the entire spring, so that the load on the belt photoreceptor can be reduced. Has the effect of being able to be lightweight. Further, by reducing the load on the belt photoreceptor, the motor for driving the belt photoreceptor can be reduced in size, so that the color image forming apparatus can be reduced in size and weight.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing details of a developing device used in the embodiment of FIG.

FIG. 2 is a front view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cleaning roller 2 Developer supply part 3 Belt photoconductor 4 Developing roller 5 Backup roller 6 Backup roller 7 Squeeze roller 8 Blade 9 PS spring 10 Charger 11 Yellow laser device 12 Yellow developing device 13 Yellow PS spring 14 Magenta laser device 15 Magenta developing Device 16 magenta PS spring 17 cyan laser device 18 cyan developing device 19 cyan PS spring 20 black laser device 21 developing device 22 black PS spring 23 drying roller 24 removal roller 26 transfer roller 27 fixing roller 28 main charger 29 drive roller 30 driven roller 31・ 32 ・ 33 Guide roller

Claims (7)

[Claims] 1. A developing device of a color image forming apparatus for sequentially forming images of respective colors of yellow, magenta, cyan and black in a predetermined order on a belt photosensitive member circulating, wherein the yellow, magenta and A developing device for each of cyan and black supplies ink to a latent image formed on the belt photoreceptor by a corresponding laser device and develops the latent image, and supplies ink to the developing roller. A developer supply unit, a squeeze roller that is provided downstream of the developing roller and removes the ink attached to a portion other than the latent image of the belt photoconductor and dries the developed image to form a film, A squeeze roller that presses the squeeze roller against a backup roller provided on the opposite side of the belt photoconductor. And a cleaning roller for cleaning the developing roller, wherein the pressing force of the spring is increased in the order of the first developing device to the fourth developing device in the order of development. 2. The pressing force of the spring is 3 to 9 kgf for the first developing device and 6 to 12 kgf for the second developing device.
f, the third developing device is 9 to 15 kgf, the fourth developing device is 12 to 18 kgf, and the first developing device, the second developing device, the third developing device, and the fourth developing device increase in this order. The developing device according to claim 1, wherein 3. The device according to claim 1, wherein the first developing device is a yellow developing device, the second developing device is a magenta developing device, the third developing device is a cyan developing device, and the fourth developing device is a black developing device. The developing device according to claim 1. 4. The method according to claim 1, wherein the first developing device is a magenta developing device, the second developing device is a yellow developing device, the third developing device is a cyan developing device, and the fourth developing device is a black developing device. The developing device according to claim 1. 5. The method according to claim 1, wherein the first developing device is a cyan developing device, the second developing device is a magenta developing device, the third developing device is a yellow developing device, and the fourth developing device is a black developing device. The developing device according to claim 1. 6. The developing device according to claim 1, wherein the squeeze roller is formed of a resin material having elasticity. 7. The developing device according to claim 6, wherein the squeeze roller is formed of urethane.