JP2021085885A - Secondary transfer device and image forming apparatus - Google Patents

Abstract

To smoothly perform a pressing/separating operation of a transfer roller.SOLUTION: A secondary transfer device controls an angular position (rotational position) of a pressure reducing cam so that the angular position of the pressure reducing cam is shifted from a butting position to a push-up position when a leading end and a rear end of a sheet enter a nip part formed by a secondary transfer roller and an opposing roller, and adjusts a duty ratio of a motor that drives the pressure reducing cam to a high duty ratio at which torque of the motor can be maintained at a predetermined magnitude for a certain period (t1 to t2), and after that (t2 to t3), adjusts the duty ratio to a low duty ratio lower than the high duty ratio in a predetermined period for returning the angular position of the pressure reducing cam from the push-up position to the butting position.SELECTED DRAWING: Figure 5

Description

The present invention relates to a secondary transfer device and an image forming device.

In many electrophotographic image forming devices, yellow (yellow) that forms a toner image of one color component along the outer peripheral surface of an intermediate transfer belt having an endless annular shape and a predetermined width, which is wound around a plurality of rollers and orbits. A configuration is adopted in which image forming units for each color such as Y), magenta (M), cyan (C), and black (K) are arranged. Then, by sequentially superimposing the toner images of each color on the intermediate transfer belt by these image forming units, a full-color color toner image is formed on the intermediate transfer belt, and this is secondarily transferred to the paper. ..

At the secondary transfer position, the intermediate transfer belt is sandwiched between a roller that supports it from the inside and a secondary transfer roller that is urged and pressed by a spring or the like from the outside to form a transfer nip. When the conveyed paper passes through the transfer nip (between the outer peripheral surface of the intermediate transfer belt and the secondary transfer roller), the toner image on the intermediate transfer belt is transferred to the paper.

Here, there is a problem that paper jam occurs when the paper passes through the transfer position. In order to deal with this problem, for example, a transfer abnormality of the transfer material (paper) conveyed by the transfer means is detected. In this case, the transfer means is separated from the image carrier (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 5-6108

However, in the apparatus disclosed in Patent Document 1, if there are variations in the dimensions of the apparatus or the motor that drives the transfer means, the transfer means is appropriately used after the transfer means is separated from the image carrier. It cannot be returned to the correct position, which may cause problems such as transfer failure.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a secondary transfer device and an image forming device capable of smoothly performing a decompression operation of a transfer roller.

In order to solve the above problems, the invention according to claim 1 is
A secondary transfer device that secondarily transfers a toner image primaryly transferred to the outer peripheral surface of an intermediate transfer belt onto paper.
An adjustment mechanism that adjusts the pressing force that the secondary transfer roller sandwiches and presses the intermediate transfer belt between the intermediate transfer belt and the opposing roller based on the displacement of the rotational position of the eccentric cam.
A control unit that controls the rotational position of the eccentric cam,
With
In the adjusting mechanism, the pressing force becomes the normal first pressing force when the rotating position of the eccentric cam is in the first position, and the pressing force is applied when the rotating position of the eccentric cam is in the second position. It is configured to have a second pressing force that is smaller than the first pressing force.
The control unit
When the front end and the rear end of the paper enter the nip portion formed by the secondary transfer roller and the opposing roller, the rotation position of the eccentric cam shifts from the first position to the second position. Control the rotation position of the eccentric cam so that
In a predetermined period when the rotation position of the eccentric cam is returned from the second position to the first position, the duty ratio of the motor that drives the eccentric cam is set to a predetermined amount for a certain period of time. The first duty ratio that can be maintained is then adjusted to a second duty ratio that is lower than the first duty ratio.
It is characterized by that.

The invention according to claim 2 is the secondary transfer apparatus according to claim 1.
The adjusting mechanism is configured so that when the rotational position of the eccentric cam reaches the first position, the eccentric cam is abutted against a predetermined abutting member.
The control unit sets the duty ratio of the motor to the first duty ratio for a certain period at least in the predetermined period until the eccentric cam is abutted against the predetermined abutting member, and then sets the duty ratio to the first duty ratio. Adjust to a duty ratio of 2,
It is characterized by that.

The invention according to claim 3 is the secondary transfer apparatus according to claim 2.
The control unit adjusts the duty ratio of the motor to a third duty ratio lower than the second duty ratio for a certain period immediately before the rotation position of the eccentric cam reaches the first position. It is characterized by that.

The invention according to claim 4 is the secondary transfer apparatus according to any one of claims 1 to 3.
The control unit is characterized in that the duty ratio is adjusted so that the average of the duty ratios of the motors in the predetermined period is equal to or less than a predetermined threshold value.

The invention according to claim 5 is the secondary transfer apparatus according to any one of claims 1 to 4.
After the rotation position of the eccentric cam reaches the first position, the control unit controls the drive of the motor at a duty ratio at which the rotation position of the eccentric cam can maintain the first position. It is a feature.

The invention according to claim 6 is the secondary transfer apparatus according to any one of claims 1 to 5.
The control unit
At the time of the initial operation, the rotation position of the eccentric cam is controlled so that the rotation position of the eccentric cam shifts from the predetermined retracted position to the first position.
The duty ratio of the motor set during the predetermined period is corrected based on the information related to the duty ratio of the motor required at the time of the initial operation.
It is characterized by that.

The invention according to claim 7
An image forming unit that forms a toner image by an electrophotographic method and first transfers the toner image to an intermediate transfer belt.
The secondary transfer device according to any one of claims 1 to 6, wherein the toner image primary transferred to the intermediate transfer belt by the image forming unit is secondarily transferred to paper.
It is an image forming apparatus characterized by the present invention.

According to the present invention, the pressure release operation of the transfer roller can be smoothly performed.

It is a front view which shows the schematic structure of the image forming apparatus which concerns on this embodiment. It is a front view which shows the schematic structure of the secondary transfer apparatus which concerns on this embodiment. It is a timing chart which shows the relationship between the nip pressure and the angular position of a decompression cam when the paper passes through a secondary transfer position. (A) is a diagram showing the angular position of the decompression cam when the abutting operation is insufficient, and (b) is a diagram showing the angular position of the decompression cam when the abutting operation is excessive. It is a figure which shows an example of the duty ratio of the motor of the adjustment mechanism set at the time of abutting operation. It is a figure which shows an example of the duty ratio of the motor of the adjustment mechanism set at the time of abutting operation. (A) to (c) are diagrams showing the setting pattern of the duty ratio of the motor of the adjusting mechanism during the period in which the abutting operation is performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The image forming apparatus 10 according to the present embodiment has a copy function of forming an image obtained by optically reading a document on a recording material such as recording paper and outputting the image, and rasterizing based on print data input from the outside. It is a so-called compound machine equipped with a printing function for forming an image on a recording paper and outputting the image. The recording material is not limited to recording paper, and may be a film, cloth, or the like. Hereinafter, the recording material will be described as paper (recording paper).

As shown in FIG. 1, the image forming apparatus 10 includes a scanner unit 11 that optically reads a document, an operation panel 12 that accepts user operations and displays various information, and a control circuit that controls the operation of the entire apparatus and performs image processing. Section 13, image forming section 20 for forming an unfixed toner image on paper, fixing device 15 for fixing an unfixed toner image on paper, and a paper feed tray 14 capable of accommodating a large number of sheets used for image forming. , A transport unit 16 for transporting the paper fed from the paper feed tray 14 and the like.

The image forming unit 20 forms a toner image by an electrophotographic method. The image forming unit 20 forms a toner image of one color component on each of the endless annular intermediate transfer belt 21 having a predetermined width and the outer peripheral surface of the intermediate transfer belt 21 wound around a plurality of rollers (primary transfer). Image forming units 22Y, 22M, 22C, 22K for each color of yellow (Y), magenta (M), cyan (C), and black (K), and a toner image formed on the outer peripheral surface of the intermediate transfer belt 21. It has a secondary transfer device 30 for secondary transfer to paper. The color-coded image forming units 22Y, 22M, 22C, and 22K are collectively referred to as the image forming unit 22.

The image forming units 22Y, 22M, 22C, and 22K have the same structure as each other, although the colors of the toners used are different. The image forming units 22Y, 22M, 22C, and 22K have a cylindrical photoconductor drum 24 as an electrostatic latent image carrier on which an electrostatic latent image is formed on the surface, and a charging device, a developing device, and the like around the cylindrical photoconductor drum 24. A transfer device, a photoconductor cleaning device, etc. are arranged and provided. Further, it includes a print head 26 composed of a laser diode (LD) which is a laser element, a polygon mirror, various lenses, a mirror, and the like.

In each image forming unit 22Y, 22M, 22C, 22K, the photoconductor drum 24 is driven by a drive unit (not shown) and rotates in a certain direction, and the charging device uniformly charges the photoconductor drum 24 and prints. The head 26 scans the photoconductor drum 24 with a laser beam controlled on / off according to a drive signal based on image data of the corresponding color to form an electrostatic latent image on the surface of the photoconductor drum 24.

The developing apparatus performs a developing step of developing an electrostatic latent image on the surface of the photoconductor drum 24 with toner to visualize it. The toner image formed on the surface of the photoconductor drum 24 is transferred (primary transfer) to the intermediate transfer belt 21 at a point where it comes into contact with the intermediate transfer belt 21. The photoconductor cleaning device removes and recovers the toner remaining on the surface of the photoconductor drum 24 after transfer by rubbing with a blade or the like.

The intermediate transfer belt 21 wound around the plurality of rollers is driven by a drive unit (not shown) and orbits in the direction of arrow A in the drawing. In the process of circulation, the toner images formed on the photoconductor drums 24 of the image forming units 22Y, 22M, 22C, and 22K of each color are sequentially transferred onto the intermediate transfer belt 21 and superposed, whereby a full-color color image is obtained. Is synthesized on the intermediate transfer belt 21. This toner image is transferred (secondary transfer) from the intermediate transfer belt 21 onto the paper by the secondary transfer device 30 arranged at the secondary transfer position D. Further, the toner remaining on the intermediate transfer belt 21 after the secondary transfer is removed from the intermediate transfer belt 21 by the cleaning device 27 provided downstream of the secondary transfer position D.

The fixing device 15 is provided in the middle of the paper transport path and downstream of the secondary transfer position D, and pressurizes the toner image transferred on the surface of the paper at the secondary transfer position D. Heat and fix.

The transport unit 16 functions to transport the paper fed from the paper feed tray 14 to the paper output tray 17 through the secondary transfer position D and the fixing device 15. The transport unit 16 is composed of a transport roller and a guide that form a transport path, a motor that drives the transport roller, and the like. Although not shown, the transport unit 16 has a paper reversing mechanism for double-sided printing that reverses the front and back of the paper that has left the fixing device 15 and feeds it back to the transport path upstream of the secondary transfer position D. I have.

The control circuit unit (control unit) 13 is configured with a CPU, ROM, RAM, and the like as main units. When the CPU executes the process according to the program stored in the ROM, each function as the image forming apparatus 10 is realized. The control circuit unit 13 controls the operation of the transport unit 16, the image forming unit 20, and the like.

In the secondary transfer device 30, the intermediate transfer belt 21 is wound by pressing the secondary transfer roller 41 whose axial direction is the width direction of the intermediate transfer belt 21 against the outer peripheral surface of the intermediate transfer belt 21 at the secondary transfer position D. An intermediate transfer belt 21 is sandwiched between the secondary transfer roller 41 and the opposing roller 28 arranged at a position facing the secondary transfer roller 41 among the plurality of hung rollers to form a transfer nip (nip portion).

As shown in FIG. 2, the secondary transfer roller 41 is incorporated in the secondary transfer unit 40. The secondary transfer unit 40 is configured by rotatably supporting the secondary transfer roller 41 on the frame member 42 and attaching a guide plate (not shown) or the like for guiding the paper to the transfer nip to the frame member 42. ..

In the secondary transfer device 30, the secondary transfer unit 40, the pressing (crimping) position where the secondary transfer roller 41 presses against the intermediate transfer belt 21 to form a transfer nip, and the secondary transfer roller 41 form an intermediate transfer belt. A crimp release portion (not shown) that displaces the secondary transfer unit 40 so as to be displaced to a separation (separation) position away from 21 and a secondary transfer roller 41 that is in the pressing position opposes the intermediate transfer belt 21. The nip pressure (pressing pressure) that is sandwiched and pressed between the 28 and 28 is temporarily applied when the front and rear ends of the paper pass through the secondary transfer position D (between the secondary transfer roller 41 and the intermediate transfer belt 21). It is configured to include an adjusting mechanism 50 for reducing the pressure.

The secondary transfer unit 40 is pivotally supported by the unit support shaft 43, and by swinging around the unit support shaft 43, the axis is located at a position separated by a predetermined distance from the unit support shaft 43 to the downstream side in the paper transport direction. The secondary transfer roller 41 having the above is displaced between the pressing position and the separating position.

The adjustment mechanism 50 rotates in the same direction as the axis of the secondary transfer roller 41 and is attached to a rotating shaft 51 driven by a motor (not shown) and rotates, and a pressure reducing cam 52 abuts on the reduced pressure cam 52 and rotates. It has a pressure reducing arm 53 that displaces the secondary transfer unit 40 at the pressing position in a direction in which the nip pressure weakens by swinging around the fulcrum 53a.

One end 53b of the pressure reducing arm 53 is a pressing portion that presses the back surface of the secondary transfer unit 40 toward the intermediate transfer belt 21, and the upper end of the spring 54 is in contact with the back surface of the pressing portion. The portion where the upper end of the spring 54 is in contact is the point of action of the decompression arm 53 in the decompression operation. On the other hand, the other end 53c of the pressure reducing arm 53 is a force point that receives the force from the pressure reducing cam 52.

Next, the operation of the secondary transfer device 30 will be described.
When the secondary transfer device 30 rotates the pressure reducing cam 52 of the adjusting mechanism 50 to a predetermined angle position (rotational position), the pressure reducing cam 52 causes the pressure point (the other end 53c) of the pressure reducing arm 53 as shown in FIG. The decompression arm 53 rotates slightly counterclockwise around the rotation fulcrum 53a and acts on the opposite end (one end 53b) of the rotation fulcrum 53a with the rotation fulcrum 53a in between. The nip pressure is reduced by displacing the spring 54 at a point to push it back. On the other hand, in the secondary transfer device 30, when the pressure reducing cam 52 is at an angle position where the pressure reducing cam 52 does not come into contact with the force point of the pressure reducing arm 53, the pressure reducing arm 53 is urged by the spring 54 at the point of action, so that the nip pressure is normally applied. It is designed to be maintained at pressure (first pressing force).

The control circuit unit 13 controls the angular position (rotational position) of the pressure reducing cam 52 so that the nip pressure is temporarily reduced when the front end and the rear end of the paper pass through the secondary transfer position D.
Specifically, for example, a sensor (not shown) for detecting the front end S1 and the rear end S2 of the paper S is provided slightly upstream of the secondary transfer position D in the paper transport direction, and the control circuit unit 13 uses this sensor. As shown in FIG. 3, a predetermined period T1 before and after the time when the front end S1 of the paper S passes through the secondary transfer position D and the said The angular position of the decompression cam 52 is the abutting position (the decompression cam 52) so that the decompression state (second pressing force) is applied for a predetermined period T2 before and after the time when the rear end S2 of the paper S passes through the secondary transfer position D. The push-up position (the position where the decompression cam 52 pushes up the force point (the other end 53c) of the decompression arm 53 (second position)) from the position (first position) abutted against the force point (the other end 53c) of the decompression arm 53. The angular position of the decompression cam 52 is controlled so as to shift to the position)). Here, when the front end S1 and the rear end S2 of the paper S pass through the secondary transfer position D, the nip pressure is temporarily reduced to alleviate the impact generated at the timing of the paper S entering and exiting. This is to suppress image deterioration such as shock noise.

Further, as shown in FIG. 3, in the secondary transfer device 30, after the nip pressure is reduced when the front end S1 of the paper S passes through the secondary transfer position D, the rear end S2 of the paper S is secondary. As a preliminary operation for reducing the nip pressure again when passing through the transfer position D, a pressing operation is performed in which the pressure reducing cam 52 is abutted against the force point (the other end 53c) of the decompression arm 53.

Here, as shown in FIG. 4A, when the rotational movement amount of the pressure reducing cam 52 during the abutting operation is insufficient and the abutting position is not reached, the rear end S2 of the paper S passes through the secondary transfer position D. During the predetermined period T2 before and after the time, when the nip pressure is shifted to the depressurized state, the decompression cam 52 starts rotating from a position that has not reached the abutting position as described above. There is a problem that the amount of decompression in T2 is insufficient. Further, as shown in FIG. 4 (b), the amount of rotational movement of the decompression cam 52 during the abutting operation becomes excessive and the abutting position is exceeded, that is, the decompression cam 52 causes the force point (the other end 53c) of the decompression arm 53. If it is pushed too much, there is a problem that the nip pressure at the time of secondary transfer of the toner image to the paper S is insufficient and transfer failure occurs. Therefore, in the secondary transfer device 30 of the present embodiment, the abutting operation is appropriately performed, and the pressure reducing cam when the rear end S2 of the paper S passes through the secondary transfer position D to shift the nip pressure to the reduced pressure state. By accurately controlling the rotation start position of 52, the above-mentioned problem is solved.

In the following, the motor control of the adjusting mechanism 50 during the abutting operation will be described in detail with reference to FIGS. 5 to 7.

FIG. 5 is a diagram showing an example of the duty ratio of the motor of the adjusting mechanism 50 set at the time of the abutting operation.
As shown in FIG. 5, when the above-mentioned abutting operation is performed in the control circuit unit 13 after a predetermined period T1 before and after the time when the tip S1 (see FIG. 3) of the paper S passes through the secondary transfer position D has elapsed. First, the angular position of the decompression cam 52 is set so that the angular position of the decompression cam 52 shifts to the abutting release position (a predetermined position where the decompression cam 52 does not abut on the force point (the other end 53c) of the decompression arm 53). Control. Then, the control circuit unit 13 stops the driving of the motor for a predetermined period (t0 to t1) at the abutting release position. Next, the control circuit unit 13 drives the motor and starts the abutting operation. The control circuit unit 13 has a duty ratio (high duty) capable of securing the torque required to rotate the motor during the first half (t1 to t2) of the period (t1 to t3) in which the abutting operation is performed. The drive of the motor is controlled by the ratio (first duty ratio)), and the drive of the motor is controlled by the duty ratio (low duty ratio (second duty ratio)) lower than the duty ratio of the first half in the latter half (t2 to t3). Control. Here, the reason why the duty ratio in the latter half (t2 to t3) is set to the low duty ratio is that when the abutting operation is completed, the decompression cam 52 abuts excessively on the force point (the other end 53c) of the decompression arm 53. This is to prevent the occurrence of transfer defects.

As shown in FIG. 6, the control circuit unit 13 divides the period in which the above-mentioned abutting operation is performed into three periods of the early stage, the middle stage, and the final stage, and the early stage (t11 to t12) has a high duty ratio (first). Duty ratio), the middle stage (t12 to t13) has a medium duty ratio (second duty ratio), and the final stage (t13 to t14) has a low duty ratio (third duty ratio) to control the drive of the motor. It may be.

Further, the duty ratio setting pattern of the motor during the period in which the abutting operation is performed is not limited to the patterns shown in FIGS. 5 and 6. For example, as shown in FIG. 7 (a), a setting pattern in which the duty ratio is reduced at a constant rate in proportion to the passage of the abutting operation time, and as shown in FIG. 7 (b), the abutting operation is performed. A setting pattern in which the duty ratio is gradually lowered in the early and final stages of the period, and the duty ratio is suddenly reduced in the middle stage. As shown in FIG. 7 (c), the duty is in the early stage of the abutting operation. The ratio may be a high duty ratio, the middle stage may be a low duty ratio, and the final stage may be a setting pattern in which the duty ratio is lowered at a constant rate in proportion to the passage of the abutting operation time. Regardless of the setting pattern, it is preferable to adjust so that the average duty ratio over the entire abutting operation time is equal to or less than a predetermined threshold value. Here, the predetermined threshold value is an index for preventing excessive abutting by the decompression cam 52 when the decompression cam 52 is abutted against the force point (the other end 53c) of the decompression arm 53. For example, it is a value obtained based on empirical facts.

As described above, in the secondary transfer device 30 according to the present embodiment, when the front end S1 and the rear end S2 of the paper S enter the nip portion formed by the secondary transfer roller 41 and the opposing roller 28, the pressure is reduced. The angular position of the decompression cam 52 is controlled so that the angular position (rotational position) of the cam 52 shifts from the abutment position to the push-up position, and the angular position of the decompression cam 52 is returned from the push-up position to the abutment position in a predetermined period. The duty ratio of the motor that drives the decompression cam 52 is set to a high duty ratio that can maintain the torque of the motor at a predetermined magnitude for a certain period of time, and then adjusted to a low duty ratio that is lower than the high duty ratio. ..
Therefore, according to the secondary transfer device 30 according to the present embodiment, the duty ratio of the motor for driving the pressure reducing cam 52 is set for a certain period of time in a predetermined period when the angular position of the pressure reducing cam 52 is returned from the pushing position to the abutting position. During the period, the torque of the motor can be maintained at a predetermined magnitude by setting the duty ratio to a high value, and thereafter, by setting the duty ratio to a low duty ratio, the power point of the pressure reducing arm 53 by the pressure reducing cam 52 ( It is possible to prevent the other end 53c) from being pushed too much. As a result, the release operation of the secondary transfer roller 41 when the front end S1 and the rear end S2 of the paper S pass through the nip portion can be smoothly performed.

Further, in the secondary transfer device 30 according to the present embodiment, the duty ratio of the motor is set for a certain period of time in a predetermined period until the pressure reducing cam 52 is abutted against the power point (the other end 53c) of the pressure reducing arm 53. Set to a high duty ratio and then adjust to a low duty ratio.
Therefore, according to the secondary transfer device 30 according to the present embodiment, it is possible to prevent the rotational movement amount of the pressure reducing cam 52 from becoming insufficient during the abutting operation, and the rotational movement amount of the pressure reducing cam 52 is increased. It can be prevented from becoming excessive.

Although the specific description has been given above based on the embodiment of the present invention, the present invention is not limited to the above embodiment and can be changed without departing from the gist thereof.

For example, in the above embodiment, in the abutting state after the angular position (rotational position) of the pressure reducing cam 52 reaches the abutting position from the abutting release position, the pressing force required for transfer (conveyance) is applied to the nip portion. The motor of the adjusting mechanism 50 may be driven with a minute duty ratio.

Further, in the above embodiment, for example, during the home position operation (initial operation) performed when the power is turned on to the image forming apparatus 10, the amount of rotational movement (unit time) of the decompression cam 52 at a predetermined duty ratio. The motor / mechanical load variation may be estimated by measuring the amount of rotational movement per hit, and the duty ratio of the motor of the adjusting mechanism 50 set at the time of the abutting operation may be adjusted (corrected).

In addition, the detailed configuration of each device constituting the image forming apparatus and the detailed operation of each device can be appropriately changed without departing from the spirit of the present invention.

10 Image forming device 11 Scanner unit 12 Operation panel 13 Control circuit unit (control unit)
14 Paper feed tray 15 Fixing device 16 Conveying unit 20 Image forming unit 21 Intermediate transfer belt 22 Image forming unit 24 Photoreceptor drum 26 Printhead 27 Cleaning device 28 Opposing roller 30 Secondary transfer device 41 Secondary transfer roller 50 Adjustment mechanism 52 Decompression mechanism 52 Cam (eccentric cam)
53 Decompression arm (butting member)
D Secondary transfer position A Circumferential direction of intermediate transfer belt S Paper

Claims (7)

A secondary transfer device that secondarily transfers a toner image primaryly transferred to the outer peripheral surface of an intermediate transfer belt onto paper.
An adjustment mechanism that adjusts the pressing force that the secondary transfer roller sandwiches and presses the intermediate transfer belt between the intermediate transfer belt and the opposing roller based on the displacement of the rotational position of the eccentric cam.
A control unit that controls the rotational position of the eccentric cam,
With
In the adjusting mechanism, the pressing force becomes the normal first pressing force when the rotating position of the eccentric cam is in the first position, and the pressing force is applied when the rotating position of the eccentric cam is in the second position. It is configured to have a second pressing force that is smaller than the first pressing force.
The control unit
When the front end and the rear end of the paper enter the nip portion formed by the secondary transfer roller and the opposing roller, the rotation position of the eccentric cam shifts from the first position to the second position. Control the rotation position of the eccentric cam so that
In a predetermined period when the rotation position of the eccentric cam is returned from the second position to the first position, the duty ratio of the motor that drives the eccentric cam is set to a predetermined amount for a certain period of time. The first duty ratio that can be maintained is then adjusted to a second duty ratio that is lower than the first duty ratio.
A secondary transfer device characterized by the fact that. The adjusting mechanism is configured so that when the rotational position of the eccentric cam reaches the first position, the eccentric cam is abutted against a predetermined abutting member.
The control unit sets the duty ratio of the motor to the first duty ratio for a certain period at least in the predetermined period until the eccentric cam is abutted against the predetermined abutting member, and then sets the duty ratio to the first duty ratio. Adjust to a duty ratio of 2,
The secondary transfer apparatus according to claim 1. The control unit adjusts the duty ratio of the motor to a third duty ratio lower than the second duty ratio for a certain period immediately before the rotation position of the eccentric cam reaches the first position. The secondary transfer device according to claim 2, wherein the secondary transfer device is characterized by the above. The one according to any one of claims 1 to 3, wherein the control unit adjusts the duty ratio so that the average of the duty ratios of the motors in the predetermined period is equal to or less than a predetermined threshold value. Secondary transfer device. After the rotation position of the eccentric cam reaches the first position, the control unit controls the drive of the motor at a duty ratio at which the rotation position of the eccentric cam can maintain the first position. The secondary transfer device according to any one of claims 1 to 4, wherein the secondary transfer device is characterized. The control unit
At the time of the initial operation, the rotation position of the eccentric cam is controlled so that the rotation position of the eccentric cam shifts from the predetermined retracted position to the first position.
The duty ratio of the motor set during the predetermined period is corrected based on the information related to the duty ratio of the motor required at the time of the initial operation.
The secondary transfer apparatus according to any one of claims 1 to 5. An image forming unit that forms a toner image by an electrophotographic method and first transfers the toner image to an intermediate transfer belt.
The secondary transfer device according to any one of claims 1 to 6, wherein the toner image primary transferred to the intermediate transfer belt by the image forming unit is secondarily transferred to paper.
An image forming apparatus comprising.

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