JPH0519588A - Multi color image forming device - Google Patents

Abstract

PURPOSE:To approximately equalize developing characteristic in each developing device regardless of the thickness of the toner layer formed previously in the multi color image forming device forming a multi color image by having an image of another color sequentially superposed over the image formed previously CONSTITUTION:A multiple number of image recording parts 5 to 8 are sequentially disposed along a surface of a photosensitive body 3, and electrifying devices 21, 25, 29, and 33, exposure devices 22, 26, 30, and 34, and developing devices 24, 28, 32, and 36 forming toner images of differing colors from each other on the surface of an image forming medium are provided to each image recording part. A means to control developing parameter of developing devices of following image recording parts according to operation of the image recording part mentioned before is also provided. A means to vary the developing bias, a means to control the speed of revolution of a developing roll, or a means to vary the distance between a surface of the developing roll and the surface of the photosensitive body, for example, can be considered as the means to control the developing parameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus for forming a multicolor image by one rotation of an image forming medium.

[0002]

2. Description of the Related Art There are various types of multicolor image forming apparatuses, one of which is to form a multicolor image on an image forming medium by one rotation of the image forming medium and to perform this multicolor image once. There is a multicolor image forming apparatus that transfers onto a recording paper in a process. In this multicolor image forming apparatus, a plurality of sets of a charger, an exposure unit, and a developing unit are arranged around the image forming medium, for example, a belt-shaped photoreceptor, corresponding to each color of black, yellow, magenta, and cyan. Then, by repeating the steps of charging, exposing and developing for each color during one rotation of the belt-shaped photoreceptor, toner images of each color are sequentially laminated on the belt-shaped photoreceptor to form a multicolor image. Then, this multicolor image is transferred onto the recording paper in one step.

[0003]

In the above-mentioned multicolor image forming apparatus, all four colors of black, yellow, magenta, and cyan are not always used, but an arbitrary color and number of these colors are used. A multicolor image is formed by the combination of.

For example, when forming a red image,
The yellow developing device and the magenta developing device are activated, and when forming a blue image, the magenta developing device and the yellow developing device are activated.

Now, assume that development is performed in the order of black, yellow, magenta, and cyan. Focusing on the magenta developing machine, when a blue image is formed, the magenta developing process is performed on the surface of the belt-shaped photoreceptor on which no toner is attached. However, in the case of forming a red image, in the magenta developing machine, the magenta developing process is performed so as to be superimposed on the previously formed yellow toner image.

In the conventional multicolor image forming apparatus, the developing machine for each color is designed to have the same dimensions, applied voltage, etc., and each color is developed under the same conditions. However,
As described above, the thickness of the toner image at the time of development varies depending on the combination of colors used, so the distance between the surface of the developing roll of the developing machine and the surface of the toner image on the photoconductor differs. . For this reason, the developing electric field is changed and the toner density is changed even though the developing machine is the same. As a result, there is a problem that the color balance of the finally formed multicolor image is different from the original one. For example, taking the case of forming the above-described red image and blue image as an example, magenta toner excessively adheres when forming a red image.

The present invention has been devised to solve the above-mentioned problems, and is a multicolor image forming a multicolor image by successively superimposing images of other colors on the previously formed image. An object of the image forming apparatus is to make the developing characteristics of the respective developing machines substantially equal.

[0008]

According to the present invention, in order to achieve the above object, a plurality of image recording portions are sequentially arranged along the surface of an image forming medium, and each image recording portion has a surface of the image forming medium. Means for controlling the development parameters in the developing machine of the subsequent image recording section in accordance with the operation of the image recording section of the preceding stage, while providing a charger, an exposure device and a developing machine for forming toner images of different colors Is provided.

[0009]

In the multicolor image forming apparatus of the present invention, the steps of charging, exposing and developing are repeated for each color to form a multicolor image on the image forming medium in a superposed state. During development, the development parameters in the developing machine are controlled according to whether or not a toner image has already been formed on the image forming medium in the previous step. For example, when developing another toner image on the image forming medium on which the toner image has already been formed, the bias of the developing device in the subsequent stage is lowered. As a result, the developing efficiency is lowered, and excessive toner is prevented from being attached due to the surface of the toner layer and the developing roll being close to each other.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below based on embodiments with reference to the drawings.

FIG. 1 is a side view showing a structural example of a multicolor image forming apparatus to which the present invention is applied.

The multicolor image forming apparatus includes an upper image forming section 1
And the lower sheet feeding section 2. Image forming unit 1
In the above, the transparent belt-shaped photosensitive member 3 functioning as an image forming medium is provided with a driving roller 4a and idler rollers 4b-4.
It is arranged vertically with respect to e, etc. Belt-shaped photoconductor 3
Is rotationally driven in the direction of arrow A by the drive roller 4a. Around the belt-shaped photoreceptor 3, a first image recording section 5, a second image recording section 6, a third image recording section 7, a fourth image recording section 8, a pre-transfer corotron 9, a developing density sensor 10, A light guide unit 11, a transfer unit 12, a pre-cleaning corotron 13, a cleaning device 14, and a ground strip 15 are arranged. The components constituting each of these image recording units and the like are arranged along a substantially vertical surface of the belt-shaped photosensitive member 3. Further, inside the lower end portion of the belt-shaped photoconductor 3, there are disposed static elimination lamps 16 that irradiate the belt-shaped photoconductor 3 from the inside before and after the transfer section 12.

The transfer section 12 is a transfer corotron 12a.
Also, the peeling corotron 12b is provided, and is arranged at the lowermost end portion of the vertically long belt-shaped photosensitive member 3 such that the sheet conveying direction is substantially horizontal. Further, adjacent to the transfer section 12, a sheet conveying device 17 and a conveying roller 18 are provided on the sheet introducing side, and a conveying belt 20 for conveying the recording sheet after transfer to the fixing device 19 is provided on the sheet discharging side. There is.

The first image recording section 5 includes the first charger 2
1. Laser light source (not shown), rotary polygon mirror 22a irradiated with laser light, motor 22b for rotating and driving this rotary polygon mirror 22a, lenses 22c, 22d, mirrors 22e, 22
A first exposure device 22, a first potential sensor 23, a first developing device 24, and the like, which are configured by f and the like, are provided. The second image recording unit 6 also includes a second charger 25, a second exposure device 26 including a light emitting diode array, a second potential sensor 27, a second developing device 28, and the like. Similarly, the third and fourth image recording units 7 and 8 also have third and fourth chargers 29 and 33 and third and fourth chargers 29 and 33, respectively.
Fourth exposure device 30, 34, third and fourth potential sensor 31,
35, third and fourth developing machines 32, 36 and the like.

The first, second, third and fourth image recording sections 5, 6, 7 and 8 are respectively made of, for example, black, yellow, magenta and cyan toners, and the belt-shaped photosensitive member 3 is formed. An image of each color is formed on top. Also,
Each potential sensor 23, 27, 31, 35 detects the surface potential of the belt-shaped photoconductor 3 in each of the image recording units 5, 6, 7, 8 and sets a control circuit (Fig. Each charger 21, 25, 29, 33 is controlled by (not shown). Further, the final development density is detected by the development density sensor 10, and the development conditions in each of the image recording units 5, 6, 7 and 8 are adjusted so that an appropriate density is obtained.
The development density sensor 10 is configured by arranging color sensor elements corresponding to respective colors in a direction perpendicular to the moving direction of the photoconductor 3.

The developing machines 24, 28, 32 and 36 are
The developing rolls 24a, 28a, 32a, 36a and the backup rolls 24b, 28b, 32b, 36b are provided, respectively. Second, third and fourth developing machines 28, 32, 3
No. 6 does not cause the toner image formed on the photoconductor 3 by the preceding developing machine to be disturbed, so a non-contact type developing device is adopted.

FIG. 2 shows an example of the structure of a non-contact type developing device.

The third developing machine 32 will be described as an example.
Inside the developer housing 32c, the donor roll, that is, the developing roll 32a and the mag roll 3 from the side of the belt-shaped photosensitive member 3 are arranged.
2d, a trimmer 32f, and an auger 32e are sequentially arranged. In the rear portion of the developer housing 32c, a magnetic two-component developer is circulated by the auger 32e, and a part of the developer is, for example, − by the variable DC power source 32g.
Attached to a mag roll 32d biased to 400V,
Further, only the toner in the developer moves from the mag roll 32d to the developing roll 32a. The developing roll 32a has 2000 Hz, 2000-2400 from the AC power source 32h.
-200 to the AC component of V from the variable DC power supply 32i
A bias voltage with a −300 V DC component superimposed is applied. Although details will be described later, the mag roll 32
The voltage applied to d is variable, and the distance between the surface of the developing roller 32a and the surface of the belt-shaped photoreceptor 3 is variable between 100 and 300 μm.

The paper feed unit 2 includes an intermediate tray 41 having paper feed devices 37, 38, 39 and 40, paper feed trays 42 and 43, a large capacity tray 44, and a paper reversal unit 4.
5 etc. are arranged. The intermediate tray 41 is provided with a plurality of switching claws 46a, 46b, 46c.
6 is provided. In addition, 47 and 48 are conveyance rolls,
49 is a reversing roll.

Next, a circuit configuration for forming an image in the above-mentioned multicolor image forming apparatus will be described with reference to FIG.

Image signals from the image input device 51, the computer 52, and the communication device 54 that communicates via the communication line 53 are supplied to the multicolor image forming device 50 through the image processing device 55. It The image signal supplied to the image processing device 55 is processed by the color separation circuit 56 into first to fourth signals.
Color component signals, for example, four color component signals of black, yellow, magenta, and cyan are separated, and the first color component signal is directly supplied to the first exposure device 22 of the first recording unit 5, and the second to fourth The color components are transmitted through the first to third delay circuits 57 to 59, respectively, to the second to fourth exposure devices 2 of the second to fourth recording units 6 to 8.
6, 30, 34. The delay times in the first to third delay circuits 57 to 59 are calculated from the exposure positions of the belt-shaped photoconductor 3 by the second to fourth exposure devices 26, 30, and 34, respectively. It corresponds to the distance of. Further, the first to fourth chargers 21, 25, 29, 33 of the respective recording units 5 to 8 and the first to fourth exposure devices 2
2, 26, 30, 34, first to fourth developing machines 24, 28,
The operations of 32 and 36 are controlled by the control device 61 that operates based on an instruction from the control panel 60.

Next, the operation of the above-described multicolor image forming apparatus will be described by taking as an example the case of forming a multicolor image from a combination of four colors of black, yellow, magenta and cyan. However, in the following description, a process of forming a red image by combining the yellow and magenta images will be described.

In this case, the second image recording section 6 and the third image recording section 7 can be sequentially operated by the control device 61 based on an instruction from the control panel 60. This operation switching is performed, for example, by sequentially applying a predetermined operating voltage or bias voltage to each charging device, each exposure device, and each developing device.

The belt-shaped photosensitive member 3, which is rotationally driven in the direction of arrow A by the drive roller 4a, first passes through the first image recording section 5, but at this time, the first image recording section 5 is in the inoperative state. Therefore, a black toner image is not formed. Next, it proceeds to the second image recording unit 6 and is charged by the second charger 25. Next, in the second exposure device 26, the surface of the photoconductor 3 is exposed by the light from the light emitting diode array modulated by the signal corresponding to the image yellow, and an electrostatic latent image is formed. Next, the electrostatic latent image is transferred to the second developing unit 28.
(See FIG. 4A), where the yellow toner T
It is developed by _Y (see FIG. 4 (b)). In the figure,
S0 is the distance between the surface of the photoconductor 3 and the surface of the toner layer T formed around the developing roll 28a, and is, for example, about 100 to about 300 μm. Further, H is the thickness of the toner layer formed by development, for example, about 5
It is 0 μm.

Next, the yellow developing portion advances to the third image recording portion 7 and is charged again by the third charger 29.
Next, in the third exposure device 30, the surface of the photoconductor 3 is exposed by the light from the light emitting diode array modulated by the signal corresponding to the magenta of the image, and the electrostatic latent image is formed. Next, the electrostatic latent image advances to the third developing unit 32, where it is developed with magenta toner T _M (FIG. 4).
(See (c)). At this time, since on the photosensitive member 3 is already attached yellow toner T _Y, a magenta toner T _M surface which is formed on top of the yellow toner T _Y toner layer T surface of the developing roller 32a distance S2 of between the yellow toner T _Y in the case of forming a yellow toner T _Y
Is shorter than the distance S1 between the surface of the developing roller 28a and the surface of the toner layer T of the developing roller 28a. Therefore, when the voltages applied to the developing rolls 28a and 32a of the second developing section 28 and the third developing section 32 are the same, the developing electric field (= applied voltage / distance) in the third developing section 32 becomes strong, The magenta toner adheres excessively.

Therefore, in the first embodiment of the present invention, the variable DC power source 3 is used in the third developing section 32 shown in FIG.
2i is adjusted so that the DC bias voltage E2 applied to the developing roller 32a is smaller than the DC bias voltage E1 applied to the developing roller 28a of the second developing section 28. That is,
See the absolute value and lower it. As a result, the developing electric field on the downstream side or the latter stage side, that is, the third developing section 32 side decreases,
The magenta toner does not adhere excessively. As a result, a red image having a good color balance is obtained on the photoconductor 3. The change of the DC bias voltage is performed by controlling each developing machine by the control device 61 shown in FIG. 3 according to the combination of colors.

The belt-shaped photosensitive member 3 further advances and passes through the fourth image recording portion 8, but at this time, since the image recording portion 8 is inoperative, cyan toner does not adhere.

Then, the charge of the toner image is adjusted by the pre-transfer corotron 9 and the charge eliminating lamp 16 to be in a state suitable for transfer.

When the toner image of each color reaches the transfer unit 12, in synchronization therewith, the recording paper is conveyed from any one of the trays 41 to 44 of the paper feeding unit 2 by any one of the paper feeding devices 37 to 40. The sheet is fed to the image forming unit 1 side along B, is further conveyed by the sheet conveying device 17 and the conveying roller 18, and comes into contact with the surface of the belt-shaped photoreceptor 3.

In the transfer section 12, the toner image of each color is transferred from the surface of the belt-shaped photoconductor 3 to the recording paper by the electric field from the transfer corotron 12a. The recording paper after the transfer is separated from the belt-shaped photoconductor 3 by the separating corotron 12b and is conveyed to the fixing device 19 by the conveying belt 20 to fix the toner image on the recording paper.

The recording paper after fixing advances, for example, in the direction of arrow C, and is directly discharged outside the apparatus by the conveying roller 47 with the image surface facing upward. When the image surface is to be ejected on the lower side, the conveying rollers 48, 49 once move the arrow D,
The sheet is conveyed in the E direction, then the rotations of the conveying rollers 48 and 49 are reversed, and the conveying roller 47 discharges it to the outside of the machine.

The toner remaining on the belt-shaped photosensitive member 3 after the transfer is removed by the cleaning device 14 after the charge state is adjusted by the charge eliminating lamp 16 and the pre-cleaning corotron 13. Further, the electric charge remaining on the photoconductor 3 is discharged through the ground strip 15 to prepare for the next image forming cycle.

In the case of double-sided copying, the recording paper after fixing advances in the direction of arrow D, is conveyed to the paper reversing unit 45 of the paper feeding unit 2 by the conveying roller 48, and is temporarily moved in the direction of arrow E by the reversing roller 49. After being conveyed, the rotation of the reversing roller 49 is reversed, the conveying direction of the recording paper is reversed in the arrow F direction, and the recording paper is stored in the intermediate tray 41 with the image surface facing upward. At this time, by changing the posture of the switching claws 46a, 46b, 46c of the switching claw device 46 according to the size of the recording paper, the recording paper is stored in the intermediate tray 41 from the proper position. This recording paper is sent to the transfer unit 12 of the image forming unit 1 again by the paper feeding device 37, and the image on the back surface of the recording paper is formed this time. In the case of double-sided printing, it goes without saying that a toner image is formed by the image forming unit 1 on each side.

Further, in the case of making two copies by superimposing on one side, the recording paper is directly fed from the conveying roller 48 to the intermediate tray 4 directly.
It may be transported to 1.

The above description is for the case of forming a red image. However, for forming a blue image, the first toner image is formed on the photoconductor 3 by the third image recording section 7. become. Therefore, in this case, the DC bias voltage applied to the developing roll 32a is set to the reference value E1.

Table 1 shows the DC bias voltages E1, E2, E3 in each developing machine for each color combination. However, E1>E2> E3. It should be noted that the operation of the black developing device is omitted here for the sake of simplicity.

[0037]

[Table 1]

Next, a second embodiment of the present invention will be described.

In the second embodiment, the voltage applied to the mag roll 32d in the developing section after the second stage, for example, the third developing section 32 shown in FIG. 2, is applied to the mag roll (not shown) of the second developing section 28. ) Smaller than the voltage applied to. That is, the absolute value is lowered. As a result, the thickness of the toner layer T1 formed on the developing roller 28a of the second developing unit 28 is smaller than that of the third developing unit 32 (see FIG. 5A).
The thickness of the toner layer T2 formed on the surface of the developing roller 32a (see FIG. 5B) becomes thin. As shown in FIG. 6, when the thickness of the toner layer of the developing roll becomes thin, the amount of development decreases, so that overdevelopment is prevented. To explain this schematically, as shown in FIG. 5, the distance S1 between the surface of the uppermost layer of the toner layer formed on the photoconductor 3 and the surface of the toner layer formed on the surface of the developing roller is the first 2 developing unit 28 and third
It becomes the same in the developing unit 32. As a result, the developing electric field in each developing section becomes equal, and an appropriate amount of toner adheres to the photoconductor 3. Similarly, in the developing unit in the subsequent stage, by appropriately decreasing the voltage applied to the mag rolls, an appropriate amount of toner adheres to each color, and a multicolor image having a good color balance can be obtained on the photoconductor 3.

The control for switching the voltage applied to the mag roll of the developing section is performed by controlling each developing machine by the control device 61 shown in FIG. 3 according to the color combination, as in the first embodiment. Done.

Next, a third embodiment of the present invention will be described.

In the third embodiment, the number of rotations of the developing roll in the developing section in the subsequent stage is lowered. As shown in FIG. 7, when the number of rotations of the developing roll is reduced, the amount of development is reduced, so that excessive development is prevented. In Table 1, the position marked E1 corresponds to the reference rotation speed, the position marked E2 corresponds to the low rotation speed, and the position marked E3 corresponds to the minimum rotation speed. The control of the number of rotations of the developing roll and the members associated therewith in the developing unit is performed by the control device shown in FIG.

Next, a fourth embodiment of the present invention will be described.

In the fourth embodiment, in the second and subsequent developing sections, for example, the third developing section 32 shown in FIG.
As schematically shown in FIG. 8, a tracking roll 62 is provided coaxially with the developing roll 32a and rotatable with respect to the developing roll 32a. The tracking roll 62 is eccentric and has three parts having different diameters. The minimum diameter r1 is selected to be suitable for first forming a toner image on the photoconductor 3, and the intermediate diameter r2 is larger than the minimum diameter r1 by one toner layer thickness, for example, 50 μm. The maximum diameter r3 is larger than the minimum diameter r1 by the thickness of two toner layers, for example, 100 μm. It should be noted that in FIG. 8, the difference in size is greatly exaggerated.

Therefore, with the tracking roll 62 in contact with the tracking receiving component 63, the photoconductor 3
By rotating the tracking roll 62 stepwise by a rotation drive device (not shown) according to the state of the upper toner, as shown in FIGS. 8A, 8B, and 8C, the surface of the photoconductor 3 is The distance between the surfaces of the developing roll 32a changes in three steps, and the distance S between the surface of the photoconductor 3 or the surface of the toner image formed on the photoconductor 3 and the surface of the developing roll 32a is always maintained constant. It That is, the developing characteristics are the same. In FIG. 8, P1 indicates the center of the developing roll 32a at the reference position, and Q1 and Q2 indicate the center of the developing roll 32a when the tracking roll 32 is rotated by 90 ° and 180 °. 8B and 8C show a state in which the developing roller 32a is retracted from the reference position by 50 μm and 100 μm, respectively. In Table 1, the position marked E1 corresponds to the minimum diameter, the position marked E2 corresponds to the intermediate diameter, and the position marked E3 corresponds to the maximum diameter.

Next, a fifth embodiment of the present invention will be described.

In the fourth embodiment, as schematically shown in FIG. 9, the developing roll 32a is coaxial with the developing roll 3a.
A tracking roll 64 is provided rotatably with respect to 2a. Then, the tracking roll 64 is brought into contact with a tracking receiving component 65 provided on the photoconductor 3 so as to be movable in a direction perpendicular to the moving direction. The tracking receiving component 65 has a pair of pins 65b erected in the receiving component main body 65a, and is biased in the tracking roll 64 direction by a compression spring 65c. Further, a drive pin 65d is erected on the receiving component body 65a, and the drive pin 65d can be moved only in a direction perpendicular to the moving direction of the photoconductor 3 by a guide member (not shown). The drive pin 65d is in contact with the inner peripheral surface of the annular body 65f which is rotationally driven by the rack gear 65e.

The rack gear 65e is moved to move the annular body 65f.
When is rotated, the drive pin 65d moves in a direction perpendicular to the moving direction of the photoconductor 3 with the drive pin 65d being in contact with the inner peripheral surface of the annular body 65f. Therefore, the tracking receiving component 65
Also moves in the same direction, and the surface of the developing roll 32a and the photoconductor 3
The distance from the surface of the changes. As a result, the distance between the surface of the photoconductor 3 or the surface of the toner image formed on the photoconductor 3 and the surface of the developing roller 32a is always maintained constant. That is, the developing characteristics are the same. In addition, the above Table 1
In, the position marked E1 corresponds to the retracted position of the tracking receiving component 65, the position marked E2 corresponds to the intermediate position, and the position marked E3 corresponds to the protruding position.

[0049]

As described above, in the present invention, since the developing characteristics in the subsequent stage are controlled according to the state of the image formed in the previous step, each developing layer is controlled regardless of the difference in toner layer thickness. The same development characteristics can be obtained with a developing machine, and a multicolor image having a good color balance can be obtained.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a multicolor image forming apparatus of the present invention.

FIG. 2 is a schematic cross-sectional view showing a configuration example of a non-contact type developing device.

FIG. 3 is a block diagram showing an example of a circuit configuration for forming an image in a multicolor image forming apparatus.

FIG. 4 is a diagram for explaining an embodiment in which the developing characteristic is controlled by controlling the developing bias voltage.

FIG. 5 is a diagram for explaining an example in which the developing characteristics are controlled by controlling the thickness of the toner layer on the developing roll.

FIG. 6 is a graph showing the relationship between the thickness of the toner layer on the developing roll and the amount of development.

FIG. 7 is a graph showing the relationship between the number of rotations of the developing roll and the amount of development.

FIG. 8 is a diagram for explaining an embodiment in which a developing characteristic is controlled by controlling a distance between a photoconductor and a developing roll by an eccentric tracking roll.

FIG. 9 is a diagram for explaining an embodiment in which a movable tracking receiving component controls a gap between a photoconductor and a developing roll to control a developing characteristic.

[Explanation of symbols]

1 image forming unit, 2 paper feeding unit, 3 belt-shaped photoconductor, 4
a drive roller, 4b-4e idler roller, 5-8
Image recorder, 9 pre-transfer corotron, 1
0 development density sensor, 11 light guide section, 12 transfer section,
12a transfer corotron, 12b peeling corotron, 1
3 pre-cleaning corotron, 14 cleaning device, 15 ground strip, 16 static elimination lamp, 17
Paper transport device, 18 transport rollers, 19 fixing device, 2
0 conveyor belts 21, 25, 29, 33 chargers, 2
2, 26, 30, 34 exposure device, 22a rotary polygon mirror, 22b motor, 22c, 22d lens, 22
e, 22f mirror, 23, 27, 31, 35 potential sensor, 24, 28, 32, 36 developing machine, 24a, 28
a, 32a, 36a developing roll, 24b, 28b, 3
2b, 36b backup roll, 32c developer housing, 32d mag roll, 32e auger, 32
f trimmer, 32g, 32i DC power supply, 32h AC power supply, 37-40 paper feeding device, 41-44 tray 4
5: paper reversing unit, 46 switching claw device, 46a, 46b,
46c switching claw, 47, 48 transport roll, 49 reversing roll, 50 multicolor image forming device, 51 image input device, 52 computer, 53 communication line, 54 communication device, 55 image processing device, 56: color separation device, 57-
59 delay circuit, 60 control panel, 61 control device,
62 tracking rolls, 63 tracking receiving parts, 64 tracking rolls, 65 tracking receiving parts, 65a receiving part body, 65b pin, 65c
Compression spring, 65d drive pin, 65e rack gear,
65f annular body

Claims (6)

[Claims] 1. A charger in which a plurality of image recording units are sequentially arranged along the surface of an image forming medium, and each image recording unit forms toner images of different colors on the surface of the image forming medium, An exposure device and a developing machine are provided respectively,
A multicolor image forming apparatus comprising means for controlling a development parameter in a developing machine of a subsequent image recording section according to an operation of an image recording section of a preceding stage. 2. The means for controlling the development parameter comprises:
The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus is means for controlling a developing bias in the developing machine. 3. The developing device comprises a developing roll for adhering toner to the image forming medium and a mag roll for supplying toner to the developing roll, and the means for controlling the developing parameter is the developing device. The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus is a unit that varies a voltage applied to the roll. 4. The developing machine includes a developing roll for adhering toner to the image forming medium and a mag roll for supplying toner to the developing roll, and the means for controlling the developing parameter is the mag roll. The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus is a unit that varies a voltage applied to the image forming apparatus. 5. The developing machine comprises a developing roll for adhering toner to the image forming medium, and the means for controlling the developing parameter is means for controlling the number of rotations of the developing roll. The multicolor image forming apparatus according to claim 1. 6. The developing machine comprises a developing roll for adhering toner to the image forming medium, and the means for controlling the developing parameter is arranged between the surface of the developing roll and the surface of the image forming medium. 2. The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus is a unit that varies the distance.