JPH09166924A - Multicolor image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a formed image of high quality with less load fluctuation and free from color slurring, etc., of a superposed image, even in the case of carrying/driving an intermediate transfer belt and forming multicolor image, by disconnecting/connecting the transmission of a rotational force between a driving shaft and a flywheel so that the flywheel may be locked/released. SOLUTION: The driving shaft 4a which is rotate to drive a pulley 3a while supporting it where the intermediate transfer belt 2 is stretched, is driven to rotate by a stepping motor 4b in a transfer direction, or a direction opposite to the transfer direction, the intermediate transfer belt 2 is driven to be carried by an intermediate transfer belt carrying/driving means 4 in the transfer direction, or the direction opposite to the transfer direction. On the same shaft of the driving shaft 4a, the flywheel 5 and an electromagnetic clutch 6 are connected, then, by turning on/off the electromagnetic clutch as a disconnecting/ connecting means 6, the rotational force of the driving shaft 4a which rotate to drive the pulley 3a of an intermediate transfer belt attaching/detaching means 3 while supporting it and the flywheel 5 is connected/disconnected so as to lock/release the flywheel 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a facsimile, a printer, etc., and in particular, toner images of different colors sequentially formed on a photosensitive member are sequentially superposed and transferred on an intermediate transfer belt. The present invention relates to a multi-color image forming apparatus that forms a multi-color image by batch-transferring to a transfer paper.

[0002]

2. Description of the Related Art As a conventional multicolor image forming apparatus, a flywheel is rotatably mounted on a rotary shaft,
By arranging the rotation transmitting means for restraining or releasing the flywheel on the rotating shaft, it is possible to obtain a good image without color misregistration and to stop the rotation of the photosensitive drum due to occurrence of jam or the like. By releasing the restraint between the flywheel and the photoconductor drum drive system or the photoconductor belt drive system that operates independently, it is possible to stop suddenly and reduce the load on the drive system when stopped. Such a technique is known (see Japanese Patent Laid-Open No. 4-288559). However, when the photoconductor and the intermediate transfer belt are interlocked and driven to be transferred in the transfer direction or in the direction opposite to the transfer direction to form a multicolor image, the load fluctuation becomes large.
Since the rotation fluctuation of one is transmitted to the other that is interlocked with each other, there has been a problem that a color shift or the like of the superimposed image occurs and a high quality formed image cannot be obtained.

[0003]

In the above-mentioned conventional multicolor image forming apparatus, the intermediate transfer belt interlocking with the photosensitive member is conveyed and driven in the transfer direction or in the reverse direction of the transfer direction to form a multicolor image. In such a case, there is a problem that the load fluctuation is large and one rotation fluctuation is transmitted to the other, which causes color misregistration of the superimposed images and the like, so that a high quality formed image cannot be obtained. Then, the subject of this invention is solving such a problem. That is, even when the intermediate transfer belt that interlocks with the photoconductor is conveyed and driven in the transfer direction or in the direction opposite to the transfer direction to form a multicolor image, the load fluctuation becomes small, and one rotation fluctuation interlocks. It is an object of the present invention to provide a multi-color image forming apparatus capable of obtaining a high quality formed image in which a color shift of a superposed image does not occur and is not transmitted to the image forming apparatus.

[0004]

In order to achieve the above object, the present invention according to claim 1 is characterized in that after toner images of different colors sequentially formed on a photoconductor are transferred one after another onto an intermediate transfer belt. In a multi-color image forming apparatus that forms a multi-color image by batch-transferring onto a transfer paper, a photoreceptor that is rotationally driven to sequentially form toner images of different colors, and a toner image formed on the photoreceptor are sequentially formed. An intermediate transfer belt that is superimposed and transferred, an intermediate transfer belt contacting / separating unit that contacts and separates the intermediate transfer belt from the photoconductor, and the intermediate transfer belt is conveyed and driven in a transfer direction or in a direction opposite to the transfer direction. The intermediate transfer belt conveyance drive means, a flywheel connected to the drive shaft of the intermediate transfer belt conveyance drive means, and the flywheel by connecting / disconnecting the transmission of rotational force between the drive shaft and the flywheel. And having a disengaging means for restraining or releasing the. According to a second aspect of the present invention, in the multicolor image forming apparatus according to the first aspect, the connecting / disconnecting means is turned on before the intermediate transfer belt comes into contact with the photosensitive member, and the drive shaft and the drive shaft are connected to each other. It is characterized in that the flywheel is restrained by connecting driving force transmission with the flywheel. According to a third aspect of the present invention, in the multicolor image forming apparatus according to the first or second aspect, the connecting / disconnecting means is turned off after being separated from a state in which the intermediate transfer belt is in contact with the photoconductor. The flywheel is released by interrupting the transmission of the driving force between the drive shaft and the flywheel. According to a fourth aspect of the present invention, in the multicolor image forming apparatus according to the first, second or third aspect, the connecting / disconnecting means is turned off before being conveyed and driven in a direction opposite to the transfer direction of the intermediate transfer belt. And transmitting the driving force between the drive shaft and the flywheel to release the flywheel.

[0005]

The multicolor image forming apparatus configured as described above is
According to the first aspect of the present invention, there is provided an intermediate transfer belt conveyance drive unit that conveys and drives the intermediate transfer belt to which the toner image on the surface of the photoconductor is transferred so as to contact and separate from the surface of the photoconductor by the intermediate transfer belt contacting and separating unit. Since the transmission of the driving force between the drive shaft and the flywheel is connected or separated by the connecting / disconnecting means to restrain or release the flywheel, the intermediate transfer belt interlocking with the photoconductor transfers in the transfer direction or Even when a multi-color image is formed by being driven in the direction opposite to the transfer direction, load fluctuations are reduced, rotation fluctuations of one are not transmitted to the other linked, and color misregistration of superimposed images does not occur. It is possible to provide a multicolor image forming apparatus capable of obtaining a high quality formed image that does not occur.

According to another aspect of the present invention, the drive shaft of the intermediate transfer belt conveying drive means is connected to the flywheel by the connecting / disconnecting means before the intermediate transfer belt contacting / separating means contacts the surface of the photoconductor with the intermediate transfer belt. Since the flywheel is constrained, load fluctuations are reduced even when the intermediate transfer belt that interlocks with the photoconductor is driven in the transfer direction or in the reverse direction of the transfer direction to form a multicolor image. Therefore, the rotation fluctuation of one is not transmitted to the other that is interlocked with each other, and a high-quality formed image in which the color shift of the superimposed image does not occur can be obtained. Further, it is possible to prevent the rotation fluctuation of the intermediate transfer belt when the flywheel is restrained at the start of the copying operation from being transmitted to the photoconductor and the drive system of the photoconductor that are interlocked with the intermediate transfer belt.

According to another aspect of the present invention, after the intermediate transfer belt contacting / separating means separates the intermediate transfer belt from the state in which the intermediate transfer belt is in contact with the surface of the photoconductor, the connecting / disconnecting means is used to connect / disconnect the drive shaft of the intermediate transfer belt conveying drive means. Since the flywheel is released by separating it from the flywheel, load fluctuations occur even when the intermediate transfer belt interlocked with the photoconductor is driven in the transfer direction or in the reverse direction of the transfer direction to form a multicolor image. It is possible to obtain a high-quality formed image in which the rotational fluctuation of one is not transmitted to the other, which is interlocked, and the color shift of the superimposed image does not occur. Further, it is possible to prevent the rotation fluctuation of the intermediate transfer belt when the flywheel is released from being transmitted to the photoconductor and the drive system of the photoconductor that are interlocked with the intermediate transfer belt.

According to another aspect of the present invention, the drive shaft of the intermediate transfer belt transport drive means is separated from the flywheel by the connecting / disconnecting means before the intermediate transfer belt transport drive means drives the intermediate transfer belt in the opposite direction to the transfer direction. Since the flywheel is released by rotating the intermediate transfer belt that is driven in the transfer direction or in the direction opposite to the transfer direction to form a multicolor image, the load fluctuation is small and one rotation is performed. It is possible to obtain a high quality formed image in which the variation is not transmitted to the other linked with each other and a color shift or the like of the superimposed image does not occur. Further, it is possible to prevent the rotation fluctuation at the time of conversion from the transfer direction of the intermediate transfer belt to the direction opposite to the transfer direction from being transmitted to the photoconductor and the drive system of the photoconductor that are interlocked with the intermediary transfer belt.

[0009]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration explanatory view of a color copying machine which is an example of a multicolor image forming apparatus to which the present invention is applied, FIG. 2 is an enlarged view of a main part thereof, and FIG. 3 is a perspective view thereof.
This color copier is equipped with an original 7 on the contact glass CG.
Scanner unit 20 for reading color images of
A color image is formed on a transfer paper as the transfer material 8 based on the image processing unit 30 that processes the digital output signal sent from the color scanner unit 20 and the image recording information of each color from the image processing unit 30. Printer section 5
0. The scanner unit 20 uses a stepping motor (not shown) as a drive source to drive the first traveling body 2
1 and the second traveling body 22 are conveyed and driven in the direction of the arrow A shown in the figure to scan the color image reading surface of the document 7. The color image surface of the original 7 has an illumination lamp 21 a provided on the first traveling body 21, a first mirror 21 b, and a second mirror 21 b.
The color sensor 24 is provided via the second mirror 22a provided on the traveling body 22, the third mirror 22b, and the imaging lens 23.
The color image information of the original 7 imaged is read for each color separation light of blue (B), green (G), and red (R), and converted into an electrical signal. Image processing unit 3
0 performs color conversion processing based on the intensity levels of the blue (B), green (G), and red (R) color-separated image signals obtained by the scanner unit 20, and black (Bk),
Recording information of color images of cyan (C), magenta (M), and yellow (Y) is obtained. The recording information converted by the image processing unit 30 is input to the printer unit 50 and sent to the laser light emitting device 51.

The image forming section of the printer section 50 includes a drum-shaped photosensitive member 1, an intermediate transfer belt 2, and a laser beam emitting device 5 which rotate in the direction of arrow B shown by a drive source not shown.
1, charging device 52, developing device 53, cleaning device 5
4, a fixing device 55 and the like. The laser light emitting device 51 converts the recording information of the color image into an optical signal, and performs optical writing corresponding to the original image through the polygon mirror 56, the f / θ lens 57, and the reflection mirror 58, and charges. An electrostatic latent image is formed on the surface 1a of the photoconductor 1 uniformly charged by the device 52. The electrostatic latent image formed on the surface 1 a of the photoconductor 1 is transferred to the developing device 5
3 is developed into a visible toner image,
The surface 1a of the photoconductor 1 by the intermediate transfer belt contacting / separating means 3
The image is transferred by the switchback method onto the intermediate transfer belt 2 which is brought into contact with or separated from the intermediate transfer belt 2.

The switchback method for preventing the transfer position deviation of each image of black (Bk), cyan (C), magenta (M), and yellow (Y) transferred onto the intermediate transfer belt 2 is an intermediate transfer. The intermediate transfer belt transport drive unit 4 for transporting and driving the belt 2, the flywheel 5 arranged to be connected to the drive shaft 4a of the intermediate transfer belt transport drive unit 4, and the transmission of the rotational force of the drive shaft 4a are connected and disconnected. The flywheel 5 is constituted by an unillustrated connecting / disconnecting means 6 for restraining or releasing the flywheel 5. First, while the intermediate transfer belt transport drive unit 4 rotates the intermediate transfer belt 2 in the forward direction indicated by the arrow C, the intermediate transfer belt contacting / separating unit 3 contacts the surface 1a of the photoconductor 1 to expose the intermediate transfer belt 2. Body 1
The first image of the first color on the surface 1a of the above is transferred onto the intermediate transfer belt 2. Next, the intermediate transfer belt contacting / separating means 3 separates the intermediate transfer belt 2 from the surface 1a of the photoconductor 1,
Only the amount of rotation in the forward direction is rotated in the return direction opposite to the direction of arrow C shown in the drawing, and the transfer position of the next color is aligned. As a result, the surface 1a of the photoconductor 1
The black (Bk), cyan (C), magenta (M), and yellow (Y) toner images formed on the image are transferred to the intermediate transfer belt 2 for a total of four times for each color. By sequentially transferring the toner images formed on the surface 1a of the photoconductor 1 onto the intermediate transfer belt 2 in a superimposed manner, the transfer positions of the four-color toner images can be formed without deviation. There is. The four-color toner image transferred onto the intermediate transfer belt 2 is transferred to the registration roller 5
The toner image transferred onto the transfer material 8 that has been conveyed at the same timing by 9 and then transferred onto the transfer material 8 is conveyed to the fixing device 55 by the paper conveying unit 60, melted and fixed, and then discharged. It is then stored on the discharge tray.

In FIG. 2, the intermediate transfer belt contacting / separating means 3 for contacting / separating the intermediate transfer belt 2 stretched from the surface 1a of the photosensitive member 1 with the pulley 3a, the tension pulley 3c, the driven pulley 3i and the driven pulley 3j, A first support member 3b supporting the pulley 3a side facing the surface 1a of the photoconductor;
Second support member 3d supporting the tension pulley 3c side
And a cam member 3e. The first support member 3b is supported by a support shaft 3f, and the second support member 3d is supported by a support shaft 3g so as to be swingable in the directions of the arrows. A pulley 3a is rotatably supported on the swing end side of the first support member 3b, and a tension pulley 3c is rotatably supported on the swing end side of the second support member 3d. A cam member 3e is arranged between the first support member 3b and the second support member 3d, and is attached so that the outer peripheral edge of the cam member 3e is in contact with the opposing side edge portions of each support member. Both support members are pressed against each other by the biasing member. The cam member 3e is disposed between the first support member 3b and the second support member 3d, and is disposed on the rotating shaft 3
It is designed to rotate about h as an eccentric axis. The distance from the rotating shaft 3h to the facing surfaces of the first supporting member 3b and the second supporting member 3d, that is, the cam lift, is calculated by the cam member 3
When e is rotated a half turn, the first support member 3b and the second support member 3d move toward and away from the surface 1a of the photoconductor 1 in the same direction while maintaining the same distance. .

In FIG. 3, a contact / separation clutch 3k is attached to the shaft end of a rotary shaft 3h that supports the cam member 3e, and the cam member 3e is rotated by the rotation of the drive motor 3l.
The half rotation step drive is performed. FIG. 4 is a front view of a main part of the intermediate transfer belt transport driving means 4 of FIG. 3, and the intermediate transfer belt transport driving means 4 supports a pulley 3a on which the intermediate transfer belt 2 is stretched and drives the rotary shaft to rotate. The intermediate transfer belt 2 is conveyed and driven in the transfer direction or in the reverse direction of the transfer direction by rotationally driving the stepping motor 4a in the transfer direction or in the reverse direction of the transfer direction by the stepping motor 4b. Reference numeral 4A is a pulley and 4B is a timing belt. Since the flywheel 5 and the electromagnetic clutch (disconnection / disconnection means) 6 are connected coaxially with the drive shaft 4a, the intermediate transfer belt contact / separation means 3 is turned on or off by turning on or off the electromagnetic clutch as the connection / disconnection means 6. The flywheel 5 can be restrained or released by connecting or separating the rotational force between the drive shaft 4a that supports the pulley 3a of FIG.

Next, the ON / OFF timing of the electromagnetic clutch as the connecting / disconnecting means 6 and its operation will be described.
At the start of the copy operation, a drive shaft 4a that stretches the intermediate transfer belt 2 and supports and rotates the pulley 3a that drives the conveyance.
However, before the rotation is started by the stepping motor 4b, the electromagnetic clutch 6 is turned on to connect the rotational force between the drive shaft 4a and the flywheel 5 to restrain the flywheel 5. After the rotation of the drive shaft 4a is started by the stepping motor 4b in a state in which the flywheel 5 is constrained, and after a certain rotation speed is reached, the intermediate transfer belt contacting / separating means 3 moves the intermediate transfer belt 2 to the photosensitive member 1 The first toner image of the first color formed on the surface 1a of the photoconductor 1 is transferred onto the intermediate transfer belt 2 by contacting the surface 1a. Therefore, it is possible to prevent the rotational fluctuation of the intermediate transfer belt 2 when the flywheel 5 is restrained at the start of the copying operation from being transmitted to the photoconductor 1 interlocking with the intermediate transfer belt 2 and the drive system of the photoconductor 1 (not shown). To be done.

Next, after the first toner image of the first color formed on the surface 1a of the photoconductor 1 is transferred onto the intermediate transfer belt 2, the intermediate transfer belt contacting / separating means 3 moves the intermediate transfer belt 2 to the photoconductor. After being separated from the surface 1a of the magnetic disk 1, the intermediate transfer belt 2 is conveyed and driven after the electromagnetic clutch 6 is turned off, and when the electromagnetic clutch 6 is turned off, the pulley 3a is supported to rotate and drive the drive shaft 4a and the flywheel 5. Flywheel 5 by cutting off torque transmission between
After releasing, the drive shaft 4a is rotationally driven in the direction opposite to the transfer direction by the stepping motor 4b. During this time, the flywheel 5 is
Continues to rotate at an almost constant rotation speed. Therefore, when the intermediate transfer belt 2 is conveyed and driven by the stepping motor 4b and the drive shaft 4a is rotationally driven in the direction opposite to the transfer direction, when the intermediate transfer belt 2 is converted from the transfer direction to the reverse direction. Is prevented from being transmitted to the photoconductor 1 which is interlocked with the intermediate transfer belt 2 and the drive system of the photoconductor 1 (not shown).

Again, by the stepping motor 4b,
The drive shaft 4a is rotated in the transfer direction to turn on the electromagnetic clutch 6.
In the N state, the rotational force between the drive shaft 4a and the flywheel 5 is connected to restrain the flywheel 5. When the stepping motor 4b causes the intermediate transfer belt 2 to rotate at a constant rotational speed of the conveyance drive, the intermediate transfer belt contacting / separating means 3 contacts the intermediate transfer belt 2 with the surface 1a of the photoconductor. Then, the second color is transferred. This operation is repeated up to the fourth color. Surface 1 of photoconductor 1
After the transfer of the fourth color from a to the intermediate transfer belt 2 is completed, the intermediate transfer belt 2 is separated from the surface 1a of the photoconductor 1 by the intermediate transfer belt contacting / separating means 3, and then the electromagnetic clutch 6 is turned off. Then, the flywheel 5 is released. Therefore, the rotation fluctuation of the intermediate transfer belt 2 when the flywheel 5 is released is prevented from being transmitted to the photoconductor 1 that interlocks with the intermediate transfer belt 2 and the drive system of the photoconductor 1 (not shown).

[0017]

As described above, according to the invention of claim 1, the intermediate transfer belt to which the toner image on the surface of the photoconductor is transferred is brought into contact with or separated from the surface of the photoconductor by the intermediate transfer belt contacting / separating means. Since the transmission of the driving force between the drive shaft of the intermediate transfer belt conveyance drive means and the flywheel which are conveyed and driven by the connecting / disconnecting means are connected or separated to restrain or release the flywheel. Even when the intermediate transfer belt that interlocks with the body is driven in the transfer direction or in the direction opposite to the transfer direction to form a multicolor image, the load fluctuation is reduced, and the rotational fluctuation of one is transmitted to the other that is interlocked. And a high-quality formed image in which no color misregistration of the superimposed images occurs can be obtained.

According to a second aspect of the present invention, the drive shaft of the intermediate transfer belt conveying drive means is connected to the flywheel by the connecting / disconnecting means before the intermediate transfer belt contacting / separating means contacts the surface of the photoconductor with the intermediate transfer belt. Since the flywheel is constrained, load fluctuations are reduced even when the intermediate transfer belt that interlocks with the photoconductor is driven in the transfer direction or in the reverse direction of the transfer direction to form a multicolor image. Therefore, the rotation fluctuation of one is not transmitted to the other that is interlocked with each other, and a high-quality formed image in which the color shift of the superimposed image does not occur can be obtained. Further, it is possible to prevent the rotation fluctuation of the intermediate transfer belt when the flywheel is restrained at the start of the copying operation from being transmitted to the photoconductor and the drive system of the photoconductor that are interlocked with the intermediate transfer belt.

According to a third aspect of the present invention, after the intermediate transfer belt contacting / separating means separates the intermediate transfer belt from the state where the intermediate transfer belt is in contact with the surface of the photoreceptor, the drive shaft of the intermediate transfer belt conveying drive means is connected / disconnected by the connecting / disconnecting means. Since the flywheel is released by separating it from the flywheel, load fluctuations occur even when the intermediate transfer belt interlocked with the photoconductor is driven in the transfer direction or in the reverse direction of the transfer direction to form a multicolor image. It is possible to obtain a high-quality formed image in which the rotational fluctuation of one is not transmitted to the other, which is interlocked, and the color shift of the superimposed image does not occur. Further, it is possible to prevent the rotation fluctuation of the intermediate transfer belt when the flywheel is released from being transmitted to the photoconductor and the drive system of the photoconductor that are interlocked with the intermediate transfer belt.

According to another aspect of the present invention, the drive shaft of the intermediate transfer belt transport drive means is separated from the flywheel by the connecting / disconnecting means before the intermediate transfer belt transport drive means drives the intermediate transfer belt in the reverse direction of the transfer direction. Since the flywheel is released by rotating the intermediate transfer belt that is driven in the transfer direction or in the direction opposite to the transfer direction to form a multicolor image, the load fluctuation is small and one rotation is performed. It is possible to obtain a high quality formed image in which the variation is not transmitted to the other linked with each other and a color shift or the like of the superimposed image does not occur. Further, it is possible to prevent the rotation fluctuation at the time of conversion from the transfer direction of the intermediate transfer belt to the direction opposite to the transfer direction from being transmitted to the photoconductor and the drive system of the photoconductor that are interlocked with the intermediary transfer belt.

[Brief description of the drawings]

FIG. 1 is a schematic configuration explanatory diagram of an example of a multicolor image forming apparatus to which the present invention is applied.

FIG. 2 is an explanatory diagram of a main part configuration of the multicolor image forming apparatus of FIG.

FIG. 3 is a perspective view of a main part configuration of the multicolor image forming apparatus of FIG.

FIG. 4 is a front view of a main part of an intermediate transfer belt conveyance driving unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 photoconductor, 1a surface, 2 intermediate transfer belt, 3 intermediate transfer belt contacting / separating means, 3a pulley, 3b supporting member, 3c tension pulley, 3d supporting member, 3e
Cam member, 3f support shaft, 3g support shaft, 3h rotation shaft,
3i driven pulley, 3j driven pulley, 3k contact / disengagement clutch, 3l drive motor, 4 intermediate transfer belt conveyance drive means, 4a drive shaft, 4b stepping motor, 5
Flywheel, 6 connecting / disconnecting means, 7 originals, 8 transfer materials, 20 color scanner section, 21 first traveling body, 21a
Illumination lamp, 21b First mirror, 22 Second traveling body, 22a Second mirror, 22b Third mirror, 23
Imaging lens, 24 color sensor, 30 image processing unit,
50 printer unit, 51 laser light emitting device, 52 charging device, 53 developing device, 54 cleaning device, 5
5 fixing device, 56 polygon mirror, 57 f / θ lens, 58 reflection mirror, 59 registration roller, 60
Paper transport unit

Claims (4)

[Claims] 1. A multicolor image forming apparatus for forming a multicolor image by transferring toner images of different colors sequentially formed on a photoconductor onto an intermediate transfer belt in sequence and then transferring them collectively onto a transfer paper. A photoconductor that is rotationally driven to sequentially form toner images of different colors, an intermediate transfer belt to which the toner images formed on the photoconductor are sequentially superposed and transferred, and the intermediate transfer belt from above the photoconductor An intermediate transfer belt contacting / separating unit that contacts and separates the intermediate transfer belt, and an intermediate transfer belt transport driving unit that transports and drives the intermediate transfer belt in a transfer direction or in a direction opposite to the transfer direction,
A flywheel connected to the drive shaft of the intermediate transfer belt conveyance drive means, and a connecting / disconnecting means for connecting / disconnecting the transmission of the rotational force between the drive shaft and the flywheel to restrain or release the flywheel. A multicolor image forming apparatus having. 2. The multicolor image forming apparatus according to claim 1, wherein the connecting / disconnecting means is turned on before the intermediate transfer belt comes into contact with the photoconductor, and the drive shaft and the flywheel are connected. A multicolor image forming apparatus characterized in that the flywheel is restrained by connecting driving force transmission between the multicolor image forming apparatus and the flywheel. 3. The multicolor image forming apparatus according to claim 1, wherein the connecting / disconnecting means is turned off after being separated from a state where the intermediate transfer belt is in contact with the photosensitive member, A multicolor image forming apparatus, characterized in that drive power transmission between the drive shaft and the flywheel is interrupted to release the flywheel. 4. The multicolor image forming apparatus according to claim 1, 2 or 3, wherein the connecting / disconnecting means is turned off before being conveyed and driven in a direction opposite to a transfer direction of the intermediate transfer belt, A multicolor image forming apparatus, characterized in that transmission of driving force between a drive shaft and the flywheel is interrupted to release the flywheel.