JPH0990779A - Multicolor image forming device - Google Patents

Abstract

(57) Abstract: To prevent image blurring when forming a multicolor image and a single color image using an endless intermediate transfer belt. An intermediate transfer belt 27 has a distance Lb from a primary transfer position with respect to a photoconductor 24 to a secondary transfer position with a paper transfer unit 63 longer than the maximum paper size, and the primary transfer is performed regardless of a color mode and a single color mode. Secondary transfer does not occur. If the distance Lb is shorter than the maximum paper size Lp, 1
When the primary transfer of the first sheet is completed, the photosensitive member 24 and the belt cleaning unit 62 are separated from the intermediate transfer belt 27, the intermediate transfer belt 27 is moved in the opposite direction at a high speed, and the tip of the toner image on the intermediate transfer belt 27 is secondary. When it passes the transfer position in the reverse direction, it again starts moving in the forward direction. At this start, the paper transfer unit 63 and the belt cleaning unit 62
Comes into contact with the intermediate transfer belt 27 to carry out secondary transfer, and when this secondary transfer is completed, the next primary transfer is carried out.

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 and a single color image using an endless intermediate transfer belt.

[0002]

2. Description of the Related Art Generally, in a multicolor image forming apparatus such as a color copying machine, a color facsimile, and a color printer,
A latent image of each color is sequentially formed on the photoconductor, developed with toner of each color, each toner image is primarily transferred so as to be superimposed on the intermediate transfer member, and the toner image on the intermediate transfer member is secondarily transferred to the paper. It is configured to transfer. FIG. 8 shows the intermediate transfer belt 64.
Shows a method of rotating the intermediate transfer belt 27 in only one direction, and FIG. 9 shows a method of rotating the intermediate transfer belt 27 back and forth.

In FIG. 8, the document is a scanner exposure device 6
The latent image is formed on the photoconductor belt 63 by the exposure image 62 that has been scanned three times by 0 and passed through the color separation filter 61. This latent image is a Y (yellow) developing device 64Y, M
(Magenta) developing device 64M and C (cyan) developing device 64
One of C is selectively developed, and the toner images of the respective colors on the photosensitive belt 63 are primarily transferred so as to be superposed on the intermediate transfer belt 64. This alignment is performed by the exposure operation start timing of the scanner exposure device 60 and the intermediate transfer belt 6
The mark detection device 65 detects the marks provided on the fourth side.

The image superposed on the intermediate transfer belt 64 is transferred by the secondary transfer roller 66 to the sheet conveyed at a timing by the registration roller 67, and the toner on this sheet is fixed by the fixing device 69. It is fixed. Here, on the intermediate transfer belt 64, the intermediate transfer belt 6
To superimpose the three colors so that the toner on 4 is not disturbed,
The intermediate transfer belt 64 is controlled so as to be separated from the photosensitive belt 63 and the secondary transfer roller 66 except during primary transfer and during secondary transfer, respectively. Further, in the single color mode in which only one color of YMC is formed, the intermediate transfer belt 64 is controlled so as to continuously contact the photoconductor belt 63 and the secondary transfer roller 66.

In the copying machine shown in FIG. 9, the color image reading device 12 illuminates the document G on the document table 15 with an illumination lamp 16,
An image is formed on the color sensor 21 by the mirror groups 17 to 19 and the lens 21, and converted into R, G, and B electric signals.
The R, G, B electrical signals are converted into Bk, C, M, Y electrical signals by image processing (not shown), and the writing unit 30 produces electrostatic latent images of the respective colors based on the electrical signals of the respective colors. The layers are sequentially formed on the photosensitive drum 24.

The photosensitive drum 24 rotates counterclockwise, and around it, a charging device 25, a four-color Bk developing device 26b, a C developing device 26c, and an M developing device 26m in which black (b) is added to YMC. A Y developing device 26y, an endless intermediate transfer belt 27, a photoconductor cleaning unit 28, and a discharge lamp 29 are arranged.

The intermediate transfer belt 27 rotates in a clockwise direction, and a paper transfer unit 63 and a belt cleaning unit 61 are also arranged around the intermediate transfer belt 27. In the color mode, the intermediate transfer belt 27 moves in the forward direction while being in contact with the photosensitive drum 24, and when the primary transfer of black for the first color is completed, the intermediate transfer belt 27 is separated from the photosensitive drum 24 and moves in the backward direction. Then, in order to perform the primary transfer of the second color C, the photosensitive drum 24 is moved again in the forward direction in a state of being in contact with the photosensitive drum 24. Further, in the monochromatic mode in which only one of black and YMC is used for image formation, the intermediate transfer belt 27 is set to the photosensitive drum 24.
It only moves in the forward direction while being in contact with.

[0008]

Here, in the apparatus shown in FIGS. 8 and 9, the image is transferred to the endless intermediate transfer belt 64, 2
7, the peripheral lengths of the intermediate transfer belts 64 and 27 are configured to be longer than the maximum paper length, and after the secondary transfer is completed,
The devices 68 and 62 for cleaning the intermediate transfer belts 64 and 27 are required before the next primary transfer. In this case, in order to reduce the mechanical size and to reduce the cost, it is necessary to make the circumferential lengths of the intermediate transfer belts 64 and 27 as short as possible. Therefore, the distance from the primary transfer position to the secondary transfer position is It is configured to be shorter than the maximum paper length.

However, when the distance from the primary transfer position to the secondary transfer position is shorter than the maximum paper length,
During the primary transfer, the paper transfer unit 63 causes the intermediate transfer belt 6 to
There is no problem in the color mode in which the sheet transfer unit 63 is separated from the sheets 4 and 27, but the sheet transfer unit 63 does not
In the monochrome mode in which the sheet is in contact with the secondary transfer is performed on the same transfer image during the primary transfer, the intermediate transfer belts 64, 2 generated when the sheet enters the secondary transfer position.
There is a problem that an image blur occurs during the primary transfer due to the speed variation of 7 and the speed variation of the intermediate transfer belts 64 and 27 due to the disturbance of the movement of the paper during the secondary transfer. Further, there is a problem in that the disturbance of the movement of the sheet that occurs when the sheet enters the fixing device causes a blur in the next primary transfer during continuous sheet passing.

Further, it is desirable that the speeds of the photoconductor, the intermediate transfer belt and the secondary transfer device are the same during image formation.
In order to achieve the perfect match, the speed variation of the intermediate transfer member at the time of the secondary transfer does not affect the primary transfer, and the drive transmission must be accurately followed. However, such an accurate driven ratio is extremely difficult for the photoconductor and the intermediate transfer belt where the force of the cleaning device acts.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a multicolor image forming apparatus capable of preventing image blurring.

[0012]

In order to achieve the above object, the present invention primarily transfers a toner image formed on an image bearing member to an intermediate transfer member, and secondarily transfers the toner image on the intermediate transfer member. In a multi-color image forming apparatus that secondarily transfers to a transfer material by means, a color mode in which a multi-color toner image is superposed on an intermediate transfer member and is primarily transferred, and a single-color mode in which a single-color toner image is primarily transferred to the intermediate transfer member In addition, the primary transfer and the secondary transfer are not performed at the same time regardless of the color mode and the monochrome mode.

Further, the distance from the primary transfer position to the secondary transfer position of the intermediate transfer member is longer than the maximum length of the transfer material, and the next toner image on the image carrier at the time of secondary transfer is primary transferred to the intermediate transfer member. It is characterized in that the interval of the transfer material is set so as not to be performed.

In the monochrome mode, the intermediate transfer member moves in the forward direction with the secondary transfer means separated from the intermediate transfer member, and the toner image on the image carrier is primarily transferred to the intermediate transfer member.
After the completion of the primary transfer, the intermediate transfer body moves away from the image carrier in the opposite direction, the leading edge of the toner image on the intermediate transfer body passes through the secondary transfer position in the opposite direction, then stops, and moves again in the forward direction. At the same time, the secondary transfer means comes into contact with the intermediate transfer body and is secondarily transferred to the transfer material of the toner image on the intermediate transfer body, and after the secondary transfer is completed, the intermediate transfer body comes into contact with the image carrier to carry out the next primary transfer. Characterized by being started.

In the multicolor image forming apparatus, the toner image formed on the image carrier is primarily transferred to the intermediate transfer member, and the toner image on the intermediate transfer member is secondarily transferred to the transfer material by the secondary transfer means. The inertia member is fixed to the drive shaft of the image carrier, and the drive of the image carrier is transmitted to the secondary transfer member.

The intermediate transfer body is driven by a dedicated drive source, and the drive source or its drive transmission mechanism delays the moving displacement amount of the intermediate transfer body in proportion to the load of the intermediate transfer body. It is characterized in that it is configured as follows.

Further, the driving of the intermediate transfer member is turned off at least during the primary transfer or the secondary transfer.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an intermediate transfer belt of a color copying machine and a structure around it as an embodiment of an image forming apparatus according to the present invention, and FIG. 2 is an example of timing for explaining an operation in a monochrome monochromatic mode. It is a chart.

The configuration shown in FIG. 1 shows in detail the intermediate transfer belt 27 of the color copying machine shown in FIG. 9 and the structure around it. The developing units 26b, 26c, 26m, and 26y respectively generate electrostatic latent images on the photoconductor 24 by Bk, C, M, and
Developing sleeves 26b-1, 26c-1, 2 that rotate so that the developer for developing with Y faces the photoconductor 9
6m-1, 26y-1, and developing paddles 26b-2, 26c-2 that rotate to suck up and agitate each developer,
26m-2, 26y-2 and a toner concentration detection sensor.

In the color mode, first, the Bk developing device 2
The developing sleeve 26b-1 of 6b is Bk on the photoconductor 24.
Rotation is started before the leading edge of the latent image of B reaches and development is performed with Bk toner, and when the trailing edge of the Bk latent image passes, rotation is stopped before the leading edge of the next C latent image arrives. Hereinafter, C,
The M and Y developing units 26c, 26m and 26y operate in the same manner to develop the C, M and Y latent images, respectively.
Further, in the monochrome mode, only the developing device corresponding to that color operates.

The intermediate transfer belt 27 is driven in the clockwise direction at the same speed as the photosensitive member 24, and Bk, C, and
The toner images of M and Y are primarily transferred so as to be superimposed on the intermediate transfer belt 27. The primary transfer is performed by the primary transfer bias roller 27 while the photoconductor 24 and the intermediate transfer belt 27 are in contact with each other.
This can be done by applying a predetermined bias voltage to -a. The intermediate transfer belt 27 is a driving roller 27-
b, it is suspended by a driven roller group including a primary transfer bias roller 27-a and a tension roller 27-c, and the drive roller 27-b is driven by a belt drive motor (not shown).

A paper transfer unit 63 and a belt cleaning unit 62 for secondarily transferring the toner image on the intermediate transfer belt 27 onto the paper P are also arranged around the intermediate transfer belt 27. The paper transfer unit 63 includes a contact / separation mechanism 63 for the secondary transfer bias roller 63-1, the roller cleaning blade 63-2, and the intermediate transfer belt 27.
-3 and the like, and the belt cleaning unit 62 includes a rubber blade 62-1 and a contact / separation mechanism 62-2 for the intermediate transfer belt 27.

In the case of full color, the contact / separation mechanisms 63-3 and 62-2 of the paper transfer unit 63 and the belt cleaning unit 62 both perform intermediate transfer until the primary transfer from the print start to the last color Y is completed. It is controlled to be separated from the belt 27, and when the primary transfer is completed, the intermediate transfer belt 27 is controlled to be contacted for the secondary transfer.

Here, in the first embodiment, the distance Lb from the primary transfer position 7 of the intermediate transfer belt 27 to the photoconductor 24 to the secondary transfer position of the paper transfer unit 63 becomes longer than the maximum paper size Lp. Is configured. Therefore, when the front end of the paper P enters the secondary transfer position of the paper transfer unit 63, the rear end of the toner image on the intermediate transfer belt 27 has already passed the primary transfer position with the photoconductor 24. Even if a slip occurs between the transfer belt 27 and the photoconductor 24, it is possible to prevent image blurring.

Next, the operation in the monochrome two-color mode will be described with reference to FIG. FIG. 2 shows a case where continuous copying of three sheets is performed. When the print start signal is turned on, the original becomes three.
The latent images are read once, and are sequentially formed on the photoconductor 24 three times in total. As for the developing devices, only the Bk developing device 26b is on, and the other developing devices 26c, 26m and 26y are off.
Then, the intermediate transfer belt 27 is continuously driven in only one direction at a constant speed, and the contact with the photoconductor 24 is such that the third toner image from the leading edge of the first toner image on the photoconductor 24 is contacted. Continue to the rear end of.

The primary transfer bias roller 27-a is on in the section from the front end to the rear end of each toner image on the photoconductor 24, and the secondary transfer bias roller 63-1 of the paper transfer unit 63 is an intermediate transfer. 1 for belt 27
The contact is continuously made from the front end of the third toner image to the rear end of the third toner image, and it is on in the section from the front end to the rear end of each toner image on the photoconductor 24. The belt cleaning unit 62 comes into contact with the intermediate transfer belt 27 as soon as it starts moving, and keeps in contact with the intermediate transfer belt 27 until the third toner image is cleaned.

In this example, the interval when the paper P is continuously conveyed to the secondary transfer position is the intermediate transfer belt 2.
The distance Lb from the primary transfer position 7 to the secondary transfer position 7 is controlled to be longer than the distance Lb. Therefore, when the front end of the paper P during the secondary transfer reaches the fixing device 24 through the secondary transfer position and when the rear end of the paper P during the secondary transfer passes through the registration rollers, Since the next toner image on 24 has not yet been primarily transferred to the intermediate transfer belt 27, image blurring can be prevented.

Next, a second embodiment will be described with reference to FIG. In the second embodiment, contrary to the first embodiment,
The intermediate transfer belt 27 has a distance Lb from the primary transfer position 7 with the photoconductor 24 to the secondary transfer position with the paper transfer unit 63.
Is smaller than the maximum paper size Lp, and image blurring is prevented by the processing shown in FIG.
FIG. 3 shows a case where three black and white continuous copies are performed as in FIG. 2, and the steps of forming a toner image on the photoconductor 24 are the same.

In the second embodiment, 1 on the photoconductor 24 is used.
When the sheet is primarily transferred to the intermediate transfer belt 27, the paper transfer unit 63 is separated from the intermediate transfer belt 27. When the primary transfer of the first sheet is completed, the intermediate transfer belt 2
When the photosensitive member 24 and the belt cleaning unit 62 are separated from 7, the intermediate transfer belt 27 moves at a high speed in the opposite direction, and when the leading edge of the toner image on the intermediate transfer belt 27 passes the secondary transfer position in the opposite direction, it stops. Start moving in the forward direction again.

At the start of this process, the paper transfer unit 63
And the belt cleaning unit 62 are the intermediate transfer belt 2
7, the secondary transfer bias roller 63-1 is turned on, and the secondary transfer is performed. Next, when this secondary transfer is completed, the photosensitive member 24 contacts the intermediate transfer belt 27, and the second sheet on the photosensitive member 24 is primarily transferred to the intermediate transfer belt 27.

Therefore, according to this second embodiment,
Even if the distance Lb from the primary transfer position to the secondary transfer position of the intermediate transfer belt 27 is shorter than the maximum sheet size Lp, the image transfer can be prevented because the primary transfer and the secondary transfer are not performed at the same time.

Next, a third embodiment will be described with reference to FIG. In the third embodiment, the distance Lb from the primary transfer position to the secondary transfer position of the intermediate transfer belt 27 is configured to be shorter than the maximum paper size Lp as in the second embodiment, and the second paper is used. Unlike the embodiment, the primary transfer and the secondary transfer are configured to be performed simultaneously.

In FIG. 4, a flywheel 71 is fixed to a shaft 70 of the photoconductor 24, and the photoconductor 24 and the flywheel 71 are both a drive motor 72 and a belt reduction mechanism 73.
Driven by Further, the rotation of the photoconductor shaft 70 is transmitted to the shaft 75 via the belt transmission mechanism 74, and the shaft 75 rotates in the same direction as the photoconductor shaft 70. Further, the belt transmission mechanism 74 is supported by the tightener 76. Incidentally, the belt reduction mechanism 73 and the belt transmission mechanism 74 may be a gear mechanism instead.

A center gear 75-1 is coaxially fixed to the shaft 75, and a gear 63-4 meshes with the center gear 75-1. The gear 63-4 is a secondary transfer bias roller 63-
It is connected to 1. The gear 63-4 and the secondary transfer bias roller 63-1 can be pulled out in the arrow direction A at the time of maintenance or replacement.

In this way, the intermediate gear 75-1 and the gear 63-
4 and the secondary transfer bias roller 63
The tensioner 76 absorbs the difference in tension when -1 comes into contact with and separates from the intermediate transfer belt 27, so that the leading edge of the paper enters the secondary transfer position and the fixing position, and the trailing edge of the paper is the registration roller. When passing through, it is possible to reduce the speed fluctuation of the intermediate transfer belt 27.

That is, as described in the conventional example, the speed fluctuation of the intermediate transfer belt 27 causes the fluctuation of the movement of the paper to change the rotation of the secondary transfer bias roller 63-1.
At the contact portion between the secondary transfer bias roller 63-1 and the outside of the image area on the intermediate transfer belt 27, the intermediate transfer belt 27 is
However, since the drive of the secondary transfer bias roller 63-1 in this embodiment is directly transmitted from the photoconductor shaft 70 provided with the flywheel 71, the secondary transfer bias roller 63-1 is driven. The speed fluctuation is less likely to occur at -1, and therefore the speed fluctuation of the intermediate transfer belt 27 can be reduced.

Here, the intermediate transfer belt 27 moves at the same speed as the secondary transfer bias roller 63-1 while the secondary transfer bias roller 63-1 is in contact, and the intermediate transfer belt 27 during the primary transfer is It moves at the same speed as the photoconductor 24 due to the electrostatic attraction force with the photoconductor 24. In addition, the tension of the tension roller 27-c that supports the intermediate transfer belt 27 has to be set to a high value, and the followability is limited, but the intermediate transfer belt 27 is driven by a dedicated drive source. By using a drive source or a drive transmission mechanism that causes a delay in the movement displacement of the transfer belt 27,
The followability of the intermediate transfer belt 27 with respect to the surface speed is further improved. As a result, naturally, the followability of the surface speed of the intermediate transfer belt 27 to the surface speed change of the secondary transfer bias roller 63-1 during the secondary transfer is also improved.

That is, the photoconductor 24 at the time of primary transfer
Between the surface speed of the intermediate transfer belt 27 and the surface speed of the intermediate transfer belt 27, and between the surface speed of the intermediate transfer belt 27 and the surface speed of the secondary transfer bias roller 63-1 during the secondary transfer.
Since minute slip due to eccentricity of the intermediate transfer belt drive roller 27-b and the like does not occur, image unevenness can be prevented.

5 and 6 show a fourth embodiment, in which the intermediate transfer belt 27 is driven by a dedicated stepping motor 80.
It is performed by In this case, the rotor shaft of the motor 80 is transmitted to the shaft 83 via the timing belt 81,
Drive shaft 27 of intermediate transfer belt via coupling 82
connected to b. In order to superimpose each image on the intermediate transfer belt 27 in the full color mode, the intermediate transfer belt 27
When reciprocating, the dedicated stepping motor 80
By using the open loop control, that is, in order to equalize the distances in the forward direction and the backward direction, only the forward / reverse rotation signal and the number of movement steps need be given as control signals
There is no need to provide position detection means.

The load torque-rotor delay angle characteristic of the stepping motor 80 shown in FIG. 6 indicates that a delay amount is generated in the displacement angle of the rotor shaft in proportion to the load torque. The speed can move in conformity with the surface speed of the photoconductor 24 during the primary transfer and in conformity with the surface speed of the secondary transfer bias roller 63-1 during the secondary transfer.

FIG. 7 shows the shaft 83 and the coupling 8 shown in FIG.
2, a clutch 84 is provided between the two, and the stepping motor 80 is turned off during the primary transfer and the secondary transfer. With this configuration, the intermediate transfer belt 27 is driven by the photoconductor 24 and the secondary transfer bias roller 63-1 during the primary transfer and the secondary transfer, respectively.
The surface speed of the intermediate transfer belt 27 can move in accordance with the surface speed of the photoconductor 24 during the primary transfer, and can match the surface speed of the secondary transfer bias roller 63-1 during the secondary transfer.

[0042]

As described above, according to the present invention, the primary transfer and the secondary transfer are not performed at the same time regardless of the color mode and the monochromatic mode. Therefore, the speed of the intermediate transfer member depends on the paper during the secondary transfer. Even if it fluctuates, it is possible to prevent image blurring during primary transfer.

Further, the distance from the primary transfer position to the secondary transfer position of the intermediate transfer member is longer than the maximum length of the transfer material, and the next toner image on the image carrier is not primary transferred to the intermediate transfer member during the secondary transfer. Since the interval of the transfer material is set like this,
Even if the speed of the intermediate transfer member varies depending on the paper at the time of the secondary transfer, the blurring of the image at the time of the primary transfer can be prevented.

In the monochromatic mode, the intermediate transfer member moves in the opposite direction to carry out the secondary transfer after the completion of the primary transfer, and the next primary transfer is started after the completion of the secondary transfer. Even if the speed of the transfer body fluctuates, it is possible to prevent image blurring during primary transfer.

Since the inertia member is fixed to the drive shaft of the image carrier and the drive of the image carrier is transmitted to the secondary transfer member,
Between the surface speed of the image carrier and the surface speed of the intermediate transfer member during the primary transfer, and between the surface speed of the intermediate transfer member and the surface speed of the secondary transfer unit during the secondary transfer, A minute slip due to the eccentricity of the driving roller or the like does not occur, and as a result, image unevenness can be prevented.

The intermediate transfer body is driven by a dedicated drive source, and the drive source or its drive transmission mechanism delays the moving displacement amount of the intermediate transfer body in proportion to the load of the intermediate transfer body. Therefore, an image is transferred between the surface speed of the image carrier and the surface speed of the intermediate transfer member during the primary transfer, and between the surface speed of the intermediate transfer member and the surface speed of the secondary transfer unit during the secondary transfer. No minute slip occurs due to eccentricity of the carrier or the drive roller of the intermediate transfer member, and as a result, image unevenness can be prevented.

Further, since the driving of the intermediate transfer member is stopped at least during the primary transfer or the secondary transfer, between the surface speed of the image carrier and the surface speed of the intermediate transfer member during the primary transfer,
Between the surface speed of the intermediate transfer member at the time of secondary transfer and the surface speed of the secondary transfer means, a minute slip due to eccentricity of the drive roller of the image carrier or the intermediate transfer member does not occur, and as a result,
Image unevenness can be prevented.

[Brief description of drawings]

FIG. 1 is a side view showing an intermediate transfer belt of a color copying machine and a structure around it as an example of an image forming apparatus according to the present invention.

FIG. 2 is a timing chart for explaining an operation in a monochrome monochromatic mode as an example.

FIG. 3 is a timing chart for explaining an operation in a monochrome monochromatic mode according to the second embodiment.

FIG. 4 is a diagram showing a driving mechanism of a photoconductor and a secondary transfer bias roller of a third embodiment.

FIG. 5 is a diagram showing a driving mechanism of an intermediate transfer belt of a fourth embodiment.

6 is a graph showing load torque-rotor delay angle characteristics of the stepping motor of FIG.

FIG. 7 is a diagram showing a driving mechanism of an intermediate transfer belt of a fifth embodiment.

FIG. 8 is a side view showing an example of a color copying machine.

FIG. 9 is a side view showing another example of a color copying machine.

[Explanation of symbols]

 24 Photoreceptor 27 Intermediate Transfer Belt 27-a Primary Transfer Bias Roller 63 Paper Transfer Unit 63-1 Secondary Transfer Bias Roller

Claims (6)

[Claims] 1. A multicolor image forming apparatus for primary-transferring a toner image formed on an image carrier to an intermediate transfer body, and secondarily transferring the toner image on the intermediate transfer body to a transfer material by a secondary transfer means. In the above, there are a color mode in which a multicolor toner image is superposed on the intermediate transfer member and is primarily transferred, and a single color mode in which a single color toner image is primarily transferred to the intermediate transfer member, regardless of the color mode and the single color mode. A multicolor image forming apparatus characterized in that primary transfer and secondary transfer are not performed simultaneously. 2. The distance from the primary transfer position to the secondary transfer position of the intermediate transfer body is longer than the maximum length of the transfer material, and the next toner image on the image carrier is primary transferred to the intermediate transfer body during the secondary transfer. 2. The multi-color image forming apparatus according to claim 1, wherein the interval between the transfer materials is set so that the transfer material does not move. 3. In the monochromatic mode, the intermediate transfer member moves in the forward direction with the secondary transfer means separated from the intermediate transfer member, so that the toner image on the image carrier is primarily transferred to the intermediate transfer member, and the primary transfer is performed. After the end, the intermediate transfer member moves away from the image carrier in the opposite direction, the leading edge of the toner image on the intermediate transfer member passes through the secondary transfer position in the opposite direction, then stops, and then moves in the forward direction again. The secondary transfer means comes into contact with the intermediate transfer body and is secondarily transferred to the transfer material of the toner image on the intermediate transfer body, and after the secondary transfer is completed, the intermediate transfer body comes into contact with the image carrier to start the next primary transfer. The multicolor image forming apparatus according to claim 1, wherein: 4. A multicolor image forming apparatus for primary-transferring a toner image formed on an image carrier to an intermediate transfer body, and secondarily transferring the toner image on the intermediate transfer body to a transfer material by a secondary transfer means. An inertia member is fixed to the drive shaft of the image carrier,
A multicolor image forming apparatus, wherein the driving of the image carrier is transmitted to the secondary transfer member. 5. The intermediate transfer body is driven by a dedicated drive source, and the drive source or its drive transmission mechanism delays the movement displacement amount of the intermediate transfer body in proportion to the load of the intermediate transfer body. The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus is configured as described above. 6. The driving of the intermediate transfer member is stopped at least during the primary transfer or the secondary transfer.
6. The multicolor image forming apparatus according to any one of 5 to 5.