JP2001249515A - Developing method, developing device and multicolor image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing method where throughput can be improved. SOLUTION: In the method, each developer carrier 7a of a multiple number of developing devices 7Y, 7M, 7C and 7K is made able to come into contact with or separate from an intermediate developer carrier 15, developer from the developer carrier 7a is carried once on the intermediate developer carrier 15 by having the developer carrier 7a abutted to the intermediate developer carrier 15 and an electrostatic latent image on a photoreceptor drum (image carrier) 1 is developed by utilizing the developer carried on the intermediate developer carrier 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method and a developing device for developing an electrostatic latent image formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic latent image dielectric, and the developing device. The present invention relates to a multicolor image forming apparatus provided with:

[0002]

2. Description of the Related Art Conventionally, various methods have been used for a multicolor image forming apparatus, for example, a method of winding a transfer material around a transfer drum or a method of using an intermediate transfer member.
Further, in order to facilitate the arrangement of each unit, a photoconductor and an intermediate transfer body are also formed in a belt shape.

Further, in order to use various transfer materials, for example, as shown in FIG.
There has been proposed a multi-color image forming apparatus using the same.

In the multicolor image forming apparatus shown in FIG.
Full-color image information is decomposed into four color image information of yellow (Y), magenta (M), cyan (C) and black (K) by a controller (not shown). 23.

On the other hand, the surface of the photosensitive drum 1 is uniformly charged in advance by a charging device 21, and the exposure device 23 exposes the photosensitive drum 1 in accordance with input information to expose an electrostatic latent image corresponding to color information. Formed on the drum 1. Thereafter, the electrostatic latent image on the photosensitive drum 1 is developed using a developer by a developing device 7Y and is visualized as a developer image. This developer image is used in a primary transfer unit D1 by using a high-voltage power supply (not shown) or the like. Is transferred to the intermediate transfer drum 11. The developer remaining on the photosensitive drum 1 without being transferred to the intermediate transfer drum 11 is removed and collected by the cleaner device 8. At this time, the secondary transfer device 3 is
Is kept out of contact with

When the same operation as above is performed for each of the colors magenta (M), cyan (C), and black (K), yellow (Y), magenta (M), and cyan (C) are placed on the intermediate transfer drum 11. ) And black (K) are formed.

After that, the transfer material P is synchronously fed to the secondary transfer portion D2, and the developer image on the intermediate transfer drum 11 is secondarily transferred to the transfer material P by the secondary transfer device 3. At this time, the developer that has not been completely transferred to the transfer material P by the secondary transfer is removed and collected by the intermediate transfer body cleaning device 4 abutting on the intermediate transfer drum 11, whereby the intermediate transfer drum 11 The surface is refreshed.

Then, the transfer material P to which the developer image has been transferred
Is transferred to a fixing device 6, where the developer image is melted and fixed on the transfer material P by being heated and pressed by the fixing device 6, whereby a full-color image is obtained.

[0009]

However, in a multicolor image forming apparatus, it is difficult to increase throughput in a conventional multicolor image forming apparatus employing a four-rotation type one-drum photosensitive drum system. was there.

Also, there is a problem that the throughput of an image such as a character having a relatively low image ratio is slower than that of the ink jet system.

Further, there is a problem that the maximum throughput cannot be obtained by the on / off mechanism of the developing device, and the cost of the device is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a developing method, a developing apparatus, and a multicolor image forming apparatus capable of increasing the throughput.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, each developer carrying member of a plurality of developing units can be brought into contact with and separated from an intermediate developer carrying member. The developer carrier is brought into contact with the intermediate developer carrier, the developer is temporarily supported on the intermediate developer carrier from the developer carrier, and the developer carried on the intermediate developer carrier is used. And developing the electrostatic latent image on the image carrier.

According to a second aspect of the present invention, the developer is once carried on the intermediate developer carrier by each developer carrier of a plurality of developing units, and the peripheral speed ratio between the intermediate developer carrier and the image carrier is reduced. The electrostatic latent image on the image carrier is developed using the developer carried on the intermediate developer carrier while changing according to the image ratio.

According to a third aspect of the present invention, each developer carrier of a plurality of developing units is opposed to each other with a predetermined gap from the surface of the intermediate developer carrier, and the developer flying in this gap is mixed with the intermediate developer. The present invention is characterized in that the electrostatic latent image on the image carrier is developed by using the developer carried on the intermediate developer carrier once by carrying the carrier on the carrier.

According to a fourth aspect of the present invention, in the developing device having a plurality of developing devices, an intermediate developer carrier is provided between the image carrier and each of the developing devices, and the developer carrier of each developing device is provided. The intermediate developer carrier is detachable from the intermediate developer carrier, the developer carrier is brought into contact with the intermediate developer carrier, and the developer is once carried on the intermediate developer carrier from the developer carrier, The electrostatic latent image on the image carrier is developed using the developer carried on the intermediate developer carrier.

According to a fifth aspect of the present invention, in the developing device having a plurality of developing devices, an intermediate developer carrier is provided between the image carrier and each of the developing devices, and each developer carrier of the plurality of developing devices is provided. The developer is once carried on the intermediate developer carrier by the body, and the development carried on the intermediate developer carrier while changing the peripheral speed ratio between the intermediate developer carrier and the image carrier according to the image ratio. The electrostatic latent image on the image carrier is developed using an agent.

According to a sixth aspect of the present invention, in the developing device having a plurality of developing devices, an intermediate developer carrier is provided between the image carrier and each of the developing devices, and the developer carrier of each developing device is provided. The intermediate developer carrier is detachable from the intermediate developer carrier, the developer carrier is brought into contact with the intermediate developer carrier, and the developer is once carried on the intermediate developer carrier from the developer carrier, The electrostatic latent image on the image carrier is developed using the developer carried on the intermediate developer carrier.

According to a seventh aspect of the present invention, there is provided a multicolor image forming apparatus comprising an image carrier and a developing device having a plurality of developing devices, wherein the intermediate portion is provided between the image carrier and each developing device of the developing device. A developer carrier is provided, and a developer is once carried on the intermediate developer carrier by the developer carrier of each developing device,
The electrostatic latent image on the image carrier is developed using the developer carried on the intermediate developer carrier.

In a multicolor image forming apparatus provided with an image carrier and a developing device having a plurality of developing devices, the invention according to claim 8 is an intermediate device between the image carrier and each developing device of the developing device. A developer carrier is provided, and the developer is once carried on the intermediate developer carrier by each developer carrier of the plurality of developing devices, and a peripheral speed ratio between the intermediate developer carrier and the image carrier is determined according to an image ratio. While developing the electrostatic latent image on the image carrier using the developer carried on the intermediate developer carrier.

According to a ninth aspect of the present invention, there is provided a multicolor image forming apparatus having an image carrier and a developing device having a plurality of developing devices, wherein the intermediate portion is provided between the image carrier and each developing device of the developing device. A developer carrier is provided, the developer carrier of each developing device can be brought into contact with and separated from the intermediate developer carrier, and the developer carrier is brought into contact with the intermediate developer carrier to remove the developer. The developer is once carried on the intermediate developer carrier from the developer carrier, and the electrostatic latent image on the image carrier is developed using the developer carried on the intermediate developer carrier. And

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a sectional view showing a schematic configuration of a multicolor image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a sectional view of a developing device portion of the multicolor image forming apparatus.

In FIG. 1, reference numeral 22 denotes a control arithmetic unit to which an image input signal D for forming an electrostatic latent image is input. Reference numeral 7 denotes a developing device according to the present invention. In the developing device 7, four colors of yellow (Y), magenta (M), cyan (C), and black (K) are stored, respectively. Developing device 7
Y, 7M, 7C and 7K are arranged in tandem in the vertical direction, and a developer carrier 7a of each of the developing devices 7Y, 7M, 7C and 7K is an intermediate developer carrier (hereinafter also referred to as TDS). 15).

In the present embodiment, the developing units 7Y, 7M, 7C, and 7K of the respective colors are one-component non-contact developing units, and each developer carrier 7a is attached to the intermediate developer carrier 15. The on-off mechanism (not shown) is configured to be able to abut at the same time. Further, since a developer bias can be applied to each developer carrier 7a, and a negative developer is used in this embodiment, a DC bias should be applied to each developer carrier 7a. Can be. Here, the developer carrier 7a has a medium resistance (approximately 10 ⁶ Ω to 10 ⁸ Ω).
cm).

In this embodiment, the intermediate developer carrier 15 has a thickness of 50 μm, an A4 size in the longitudinal direction, a diameter of about 140 mmφ, and a low volume efficiency of 10 ⁶ to 10.
A polyimide product having a resistance of ¹² Ωcm was used. The intermediate developer carrier 15 is provided with an intermediate developer carrier drive roller 1.
6 and the intermediate developing unit roller 17 and are driven to rotate. That is, the intermediate developer carrier driving roller 16 is driven by the intermediate developer carrier 62, and the intermediate developer carrier 62 is driven and controlled by the intermediate developer carrier controller 61 so that the intermediate developer carrier 15 is moved to a predetermined position. It is rotationally driven at a rotational speed. A developing bias can be applied to the intermediate developing unit roller 17 using a power supply (not shown).

In FIG. 1, reference numeral 11 denotes an intermediate transfer belt.
And the intermediate transfer belt driving roller 10 and the secondary transfer unit roller 12 are suspended and driven. Here, the intermediate transfer belt driving roller 10 is driven by the intermediate transfer belt driving device 52, and the intermediate transfer belt driving device 52 is driven and controlled by the intermediate transfer belt driving control device 51, so that the intermediate transfer belt 11 is rotated at a predetermined rotational speed. Driven by In FIG. 1, reference numeral 4 denotes an intermediate transfer member cleaning device for cleaning the intermediate transfer belt 11.

Here, the developing units 7Y, 7M, 7C,
The 7K developer carrier 7a is provided with driving devices 32Y and 32Y, respectively.
M, 32C, and 32K, and the driving devices 32Y, 32M, 32C, and 32K are driven by the control device 31.
Each developer carrier 7a is driven at a predetermined rotation speed by being driven and controlled by Y, 31M, 31C and 31K.

Next, the operation of the multicolor image forming apparatus according to the present embodiment will be described with reference to FIG.

As one aspect of the present embodiment, when the peripheral speed Ps (TDS) of the intermediate developer carrier 15 is set to 3: 1 with respect to the peripheral speed Ps (ITB) of the intermediate transfer belt 11,
That is, Ps (ITB) = 188 mm / sec, Ps (T
DS) = 47 mm / sec.

A photosensitive drum 1 serving as an image carrier is driven by a photosensitive drum driving device 4 controlled by a photosensitive drum control device 41.
2, the photosensitive drum 1 is uniformly rotated by a charging device 21 such as a charging roller or a corona charger.

Here, 23 is an exposure device, D is the image input signal, 22 is the control operation device for separating the input information into each color, and a laser beam modulated by the image signal of each color by the exposure device 23. An electrostatic latent image of each color is formed on the photosensitive drum 1 by forming an optical signal such as the above on the photosensitive drum 1. Note that a self-scanning system such as an LED may be used as the optical system.

On the other hand, in each of the developing devices 7Y, 7M, 7C, and 7K, the first color yellow (Y) is developed on the entire surface of the intermediate developer carrier 15 in the longitudinal direction and approximately 100 mm in the circumferential direction. The powder image is formed in a belt shape by carrying the agent. Here, a powder image was formed in a region having a length of 100 mm in the circumferential direction of the intermediate developer carrier 15, but this length is generally determined by the peripheral speed Ps (IT
B) and the peripheral speed Ps (TDS) of the intermediate developer carrier 15. That is, the peripheral speed Ps of the intermediate transfer belt 11
(ITB) and the peripheral speed Ps (TD
As the difference in the ratio of S) increases, the area of the entire yellow (Y) powder image decreases, and as the ratio decreases, the area of the entire yellow (Y) powder image increases.
Note that the ratio between the peripheral speed Ps (ITB) of the intermediate transfer belt 11 and the peripheral speed Ps (TDS) of the intermediate developer carrier 15 is determined by the developing units 7Y, 7M, and 7M that form a powder image on the intermediate developer carrier 15.
7C and 7K and the bias value applied between them.

Thus, the medium-resistance intermediate developer carrier 15 used in the present embodiment can carry a large amount of developer. That is, in the present embodiment, the intermediate developer carrier 15 and the developer carrier 7a
By controlling the value of the developing bias applied during the period, it is possible to realize a state in which the developer in the area of the entire powder image at the first developing site can achieve a substantially saturated density over the entire A4 size. I got it. In other words,
This means that three times the amount of developer on the intermediate developer carrier 15 is carried on the intermediate developer carrier 15 from the developing units 7Y, 7M, 7C, and 7K.

Subsequently, the above process is sequentially performed for magenta (M), cyan (C), and black (K), so that yellow (Y), magenta (M), cyan (C) ) And black (K) band-shaped powder images are each formed with a width of 100 mm.

In the above process, the developing devices 7Y and 7Y are arranged so as not to disturb the powder image before the first color or the like.
M, 7C, 7K are provided with an on / off mechanism, and a slight gap is formed between the developer carrier 7a of each of the developing units 7Y, 7M, 7C, 7K and the entire surface powder of each color. This situation is shown in FIGS.

Subsequently, of the image information color-separated into yellow (Y) magenta (M), cyan (C) and black (K), first, an optical signal corresponding to yellow (Y) information is exposed to the exposure device 23. An image is formed on the photosensitive drum 1 to form an electrostatic latent image on the photosensitive drum 1.
The electrostatic latent image formed on the photosensitive drum 1 is formed on the photosensitive drum 1 as a yellow (Y) developer image by performing non-contact development corresponding to yellow (Y) information at the developing site. Be visualized. At this time, the peripheral speed of the photosensitive drum 1 is 188 mm / sec, and the developer image on the photosensitive drum 1 is primarily transferred onto the intermediate transfer belt 11 by the primary transfer unit roller 9. At this time, the secondary transfer device 3 is separated from the intermediate transfer belt 11, and the primary transfer residual developer remaining on the photosensitive drum 1 without being transferred to the intermediate transfer belt 11 is removed by the cleaner device 8. Collected.

In this embodiment, the peripheral length of the intermediate transfer belt 11 is set to the length in the longitudinal direction of A4 size + α, and α depends on the interval between the colors on the intermediate developer carrier 15. are doing. However, this is not the case depending on the driving method of the intermediate transfer belt 11 or the intermediate developer carrier 15.

Subsequently, magenta (M) and cyan (C)
Similarly, for black (K), developer images corresponding to image information are formed on the photosensitive drum 1, and each developer image is primarily transferred onto the intermediate transfer belt 11 sequentially. At this time, it is needless to say that it is necessary to perform control so that the yellow (Y), magenta (M), cyan (C) and black (K) colors do not shift by a sequence calculation or a sensor (not shown). .

In the above, one of the intermediate developer carriers 15
Since four rotations of the intermediate transfer belt 11 are possible by the number of rotations, the throughput for each color is increased, and high-speed multicolor image formation is possible.

The remaining developer remaining on the intermediate developer carrier 15 is used for the next development. Therefore, it is necessary to control the rotation of the intermediate developer carrier 15. In particular, in the case of continuous black single color, it is necessary to controlly rotate the intermediate developer carrier 15 so that black can always be developed.

The four color developer images of yellow (Y), magenta (M), cyan (C) and black (K) formed on the intermediate transfer belt 11 are synchronously fed from the cassette CT. Secondary transfer is performed by the secondary transfer device 3 on the transferred transfer material P. The transfer material P that has received the transfer of the developer images of the four colors is guided to the fixing device 6 along the transport guide H, and the developer is heated and melted by the fixing device 6, so that the developer is added to the transfer material P. The image is fixed to form a full-color image. Here, the developer remaining on the intermediate transfer belt 11 without being transferred to the transfer material P by the secondary transfer is removed and collected by the intermediate transfer body cleaning device 4, whereby the surface of the intermediate transfer belt 11 is refreshed. .

In this embodiment, the contact developing method is used as the developing method at the second developing portion, but a non-contact developing method may be used. Although the contact developing method was used as the developing method at the first developing site, it is needless to say that a non-contact developing method using a two-component developer or another developing method may be used.

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

The present embodiment is characterized in that the peripheral speed ratio between the intermediate developer carrier and the image carrier is changed according to the image ratio.

1) Example 1: FIG. 4 is a sectional view showing a schematic configuration of a multicolor image forming apparatus according to Example 1 of the present embodiment. In this figure, the same elements as those shown in FIG. The same reference numerals are given, and the description thereof will be omitted below.

In FIG. 4, reference numeral 72 denotes an image ratio calculating device. The image ratio calculating device 72 receives an image input signal D for forming an electrostatic latent image, and outputs a signal within a page or a continuous page. The image ratio in each page is calculated in the image ratio calculation device 72 for each of yellow (Y), magenta (M), cyan (C), and black (K). At this time, it is most common to calculate the ratio with respect to the maximum image printing area. However, the calculation may be performed on an area for guaranteeing an image.

In this embodiment, the image ratio for the maximum image printing area is calculated for each color. Here, a description will be given assuming that the maximum image ratio is 100%. For example, since the image ratio is 5% in a normal text document, in the present embodiment, the image ratio of black (black) is 5%, and the image ratio of color (yellow, magenta, and cyan) is described for simplicity. Is 0.5% (for convenience, Y, M,
C and K are each set to 0.5%).

When a pictorial image such as a photograph is included in a part of the document, the image ratio is, for example, 3
It is considered to be around 0% to 70%. Needless to say, when a photograph of a star in the night sky is printed out with a black background, the image ratio is considered to be about 95% or more (but the color ratio is reduced in this case).

In this embodiment, the developing units 7Y, 7M, 7C and 7K of the respective colors of the developing device 7 are provided in the first embodiment.
A non-magnetic one-component contact developing device was used in the same manner as in Example 1. The developing sleeves 7a of the developing devices 7Y, 7M, 7C, and 7K used in the present embodiment are the developing sleeve driving devices 32Y and 32Y.
M, 32C, and 32K. At this time,
The information of each color from the image ratio calculation device 72 is input to the intermediate developer carrier drive control device 61, and the rotation speed of the intermediate developer carrier 15 is controlled by the drive device 62 according to the image ratio.

As described above, for example, the yellow (Y) electrostatic latent image formed on the photosensitive drum 1 is developed by the developer at the second developing portion and is visualized as a developer image.
This developer image is subsequently secondarily transferred onto the intermediate transfer belt 11.

This embodiment shows an example in which the transfer material P is A4 size. The peripheral speed of the photosensitive drum 1 is 48 mm / sec or more
The peripheral speed can be continuously changed by the photosensitive drum control device 41 and the photosensitive drum drive device 42.

Each color information continues to be magenta (M),
The toner images are developed with cyan (C) and black (K) developers and visualized as developer images, and the respective developer images are sequentially secondarily transferred onto the intermediate transfer belt 11.

The transfer material P to which the developer images of the respective colors have been transferred is conveyed at least in accordance with the peripheral speed of the intermediate transfer belt 11, guided to the fixing device 6, and developed by the fixing device 6. By heating and melting the developer, the developer image is fixed on the transfer material P, and a full-color image is formed.

The fixing property of the developer used in this embodiment is such that the peripheral speed of the photosensitive drum 1 is 48 mm / sec to 188 mm / sec.
In this case, the peripheral speed of the photosensitive drum 1 does not need to be changed in accordance with the paper feeding / conveying speed, but the control temperature and the pressing force of the fixing device 6 are changed in accordance with the image ratio. Needless to say, various transfer materials P can be finely handled.

In this embodiment, each of the developing units 7Y, 7M,
In 7C and 7K, the peripheral speed of each developer carrying member 7a is 48 m
It was variable in the range of m / sec to 188 mm / sec.

Further, a laser beam scanning optical system was used for the exposure device 23. The speed of the exposure device 23 was also controlled in synchronization with the rotation of the photosensitive drum 1 so that the scanning density did not change. As can be easily analogized, use of a self-scanning optical system such as an LED makes it easy to make the exposure amount constant according to a change in the peripheral speed of the photosensitive drum 1, and
The amount of exposure can be instantaneously controlled without delay in rotation change as seen in a laser scanner.

Table 1 shows the throughput for various image ratios in the first embodiment in comparison with the comparative example. In this embodiment, for the sake of convenience, the image ratios of yellow (Y), magenta (M), and cyan (C) are the same.

[0059]

As shown in Table 1, in the comparative example, the throughput is constant regardless of the image ratio. That is, the throughput of black was 8 ppm, and the throughput of full color was 2 ppm.

In this embodiment, the throughput is optimized according to the image ratio of each color, and black is 8 pp.
For m, full color, 2 ppm to 6 ppm could be realized in a form that maximized the performance of the developing device.

As described above, changing the peripheral speed of the developer carrier and the photosensitive drum according to the image ratio is very effective in maximizing the throughput while minimizing the deterioration of the developer. I can understand.

In this embodiment, since the laser scanner is used as the exposure device, the peripheral speeds of the developer carrier and the photosensitive drum are controlled by the average value of 1 to 5 sheets. Change the peripheral speed of the photosensitive drum for each page,
It can be inferred that weighting can be easily controlled for each page. The control as shown in this embodiment can also be performed by an external signal. In particular, a self-scanning exposure apparatus such as an LED can perform fine control.

2) Embodiment 2: In this embodiment, the image ratios Gth (Y), Gth (M), Gth
(C) and Gth (K) are set, and the image ratio is smaller than the image ratio Gth (Y), Gth (M), Gth (C), Gth (K) of each color. At least one color has an image ratio Gth (Y), Gth (M),
It is characterized by increasing the speed of the image carrier in a state larger than Gth (C) and Gth (K). FIG. 5 shows an outline thereof. In FIG. 5, the same elements as those shown in FIG. 4 are denoted by the same reference numerals.

Also in this embodiment, the image ratio in each color of the average is calculated by the image ratio calculation device 72 assuming a continuous document of 5 pages.

In this embodiment, the peripheral speed of the photosensitive drum 1 was changed while the peripheral speed of the intermediate developer carrier 15 was kept constant. Table 2 shows the throughput with respect to various image ratios in this embodiment in comparison with the comparative example.

[0066]

Here, the peripheral speed of the intermediate developer carrier 15 is 72 m.
m / sec, and the same image ratio Gth (Y), Gth (M), Gth (C), Gth (K) is used for each color to simplify the description. Was. That is, Gth (Y) = Gth (M) = Gth (C) = Gth (K)
= 69%.

That is, when the image ratio calculation device 72 determines that the image ratio is ≤69% for each color, the photosensitive drum drive control device 41 of the photosensitive drum 1 causes the photosensitive drum drive device 42 to change from 48 mm / sec to 144 mm. / Se
As shown in Table 2, a speed increase command for c is output, and as a result, a throughput of 2 ppm to 6 ppm for full color and 8 ppm to 24 ppm for black can be obtained.

The Gth (Y), Gth (M), Gth
(C), Gth (K) is 70% for each color to 1
00% is defined as the minimum image ratio required for obtaining sufficient density, and in this embodiment, density = 1.1 was used as a reference.

When the image ratio is low for each color, sufficient development can be performed even if the supply amount of the developer is large, which is effective for increasing the throughput.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a sectional view of a developing device portion of the multicolor image forming apparatus according to the present embodiment, and FIG. 7 is a partial perspective view for explaining a developing method according to the present embodiment. 6 and 7, FIG.
The same elements as those shown in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted below.

In this embodiment, in each of the above-described embodiments, the developer carrying member carrying the developer is opposed to the intermediate developer carrying member at a required minute gap from the surface of the intermediate developer carrying member.
It is characterized in that the developer flying in the gap is once carried on the intermediate developer carrier.

In the present embodiment, since a so-called non-contact developing method and a non-contact developing device are used in the first developing portion, an on / off mechanism of each of the developing devices 7Y, 7M, 7C and 7K is not required. Therefore, the configuration of the developing device 7 is simplified, and the cost of the multicolor image forming apparatus can be reduced.
Further, there is an advantage that the interval between the developing devices 7Y, 7M, 7C, and 7K can be suppressed as small as possible. In the non-contact method, it goes without saying that a DC electric field and an alternating electric field can be applied to the developing bias.

[0073]

As is apparent from the above description, according to the present invention, the developer is once carried on the intermediate developer carrier by each developer carrier of the plurality of developing units, Since the electrostatic latent image on the image carrier is developed using the developer carried on the body, the effect of increasing the throughput and enabling high-speed multicolor image formation is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a multicolor image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a developing device portion of the multicolor image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a view for explaining a developing method according to the first embodiment of the present invention.

FIG. 4 is a sectional view illustrating a schematic configuration of a multicolor image forming apparatus according to Example 1 of Embodiment 2 of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a multicolor image forming apparatus according to a second embodiment of the second embodiment of the present invention.

FIG. 6 is a sectional view of a developing device portion of a multicolor image forming apparatus according to Embodiment 3 of the present invention.

FIG. 7 is a view for explaining a developing method according to a third embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a conventional multicolor image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photosensitive drum (image carrier) 7 Developing device 7a Developer carrier 7Y, 7M, 7C, 7K Developing device 15 Intermediate developer carrier 22 Control arithmetic unit 72 Image ratio arithmetic unit

[Table 1]

[Table 2]

Claims (9)

[Claims] An image forming apparatus according to claim 1, wherein each developer carrier of the plurality of developing devices can be moved toward and away from the intermediate developer carrier, and the developer carrier is brought into contact with the intermediate developer carrier to discharge the developer. The developer is once carried on the intermediate developer carrier from the developer carrier, and the electrostatic latent image on the image carrier is developed using the developer carried on the intermediate developer carrier. Development method. 2. A developer is once carried on an intermediate developer carrier by each developer carrier of a plurality of developing units, and a peripheral speed ratio between the intermediate developer carrier and the image carrier is changed according to an image ratio. A developing method for developing the electrostatic latent image on the image carrier using a developer carried on the intermediate developer carrier while performing the developing. 3. A developer carrier of a plurality of developing units is opposed to each other with a predetermined gap from the surface of the intermediate developer carrier, and the developer flying in this gap is once carried on the intermediate developer carrier. And developing the electrostatic latent image on the image carrier using the developer carried on the intermediate developer carrier. 4. A developing device having a plurality of developing devices, wherein an intermediate developer carrier is provided between an image carrier and each of the developing devices, and the developer carrier of each developing device is replaced with the intermediate developer carrier. The developer carrying member is brought into contact with the intermediate developer carrying member, and the developer is once carried on the intermediate developer carrying member from the developer carrying member. A developing device for developing an electrostatic latent image on an image carrier using a developer carried thereon. 5. A developing device having a plurality of developing devices, wherein an intermediate developer carrier is provided between the image carrier and each of the developing devices, and the developer is interposed by each developer carrier of the plurality of developing devices. Once carried on the developer carrier, while changing the peripheral speed ratio of the intermediate developer carrier and the image carrier according to the image ratio,
A developing device for developing an electrostatic latent image on an image carrier using a developer carried on an intermediate developer carrier. 6. A developing device having a plurality of developing devices, wherein an intermediate developer carrier is provided between an image carrier and each of the developing devices, and the developer carrier of each developing device is replaced with the intermediate developer carrier. The developer carrying member is brought into contact with the intermediate developer carrying member, and the developer is once carried on the intermediate developer carrying member from the developer carrying member. A developing device for developing an electrostatic latent image on an image carrier using a developer carried thereon. 7. A multicolor image forming apparatus comprising an image carrier and a developing device having a plurality of developing devices, wherein an intermediate developer carrier is provided between the image carrier and each developing device of the developing device. The developer is once carried on the intermediate developer carrier by the developer carrier of each developing device, and the electrostatic latent image on the image carrier is used by using the developer carried on the intermediate developer carrier. A multi-color image forming apparatus characterized by developing. 8. A multicolor image forming apparatus comprising an image carrier and a developing device having a plurality of developing devices, wherein an intermediate developer carrier is provided between the image carrier and each developing device of the developing device. The developer is once carried on the intermediate developer carrier by each developer carrier of the plurality of developing devices, and the intermediate speed is changed while changing the peripheral speed ratio between the intermediate developer carrier and the image carrier according to the image ratio. A multicolor image forming apparatus, wherein an electrostatic latent image on an image carrier is developed using a developer carried on the developer carrier. 9. A multicolor image forming apparatus comprising an image carrier and a developing device having a plurality of developing devices, wherein an intermediate developer carrier is provided between the image carrier and each developing device of the developing device. The developer carrying member of each developing unit can be brought into contact with and separated from the intermediate developer carrying member, and the developer carrying member is brought into contact with the intermediate developer carrying member to move the developer from the developer carrying member to the intermediate developer carrying member. Forming a multicolor image by temporarily supporting the developer on a developer carrier and developing the electrostatic latent image on the image carrier using the developer carried on the intermediate developer carrier. apparatus.