JP2021110798A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can improve productivity.SOLUTION: An image forming apparatus 100 is an apparatus that conveys a recording medium P along a conveyance path and forms an image on the recording medium P, and comprises: an intermediate transfer body 251 in an endless belt shape; a secondary transfer unit 252; a cleaning mechanism 256; and a control unit 10. When the intermediate transfer body 251 is normally rotated, if the arrival of the recording medium P to the secondary transfer unit 252 is predicted to be delayed compared with the arrival of a toner image to the secondary transfer unit 252, the control unit 10 reversely rotates the intermediate transfer body 251 to perform control such that the toner image on the intermediate transfer body 251 is removed by the cleaning mechanism 256.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus.

The image forming apparatus of Patent Document 1 includes an intermediate transfer belt, a secondary transfer roller, and a cleaning mechanism. When a delay in feeding paper to the secondary transfer roller is predicted, this image forming apparatus idles the intermediate transfer belt for about one round with the secondary transfer roller and the cleaning mechanism retracted, and then spins the intermediate transfer belt idlely. The toner image is transferred from the secondary transfer roller to the sheet at a predetermined timing.

Japanese Unexamined Patent Publication No. 2001-356556

In the image forming apparatus described in Patent Document 1, when a delay in feeding paper to the secondary transfer roller is predicted, the intermediate transfer belt is idled by about one revolution, so that the productivity is impaired.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of improving productivity.

The image forming apparatus according to the present invention is an image forming apparatus that conveys a recording medium along a conveying path and forms an image on the recording medium, and includes an image carrier and an endless belt-shaped intermediate transfer body. The exposed unit, the developing unit, the primary transfer unit, the secondary transfer unit, the cleaning mechanism, and the control unit are provided. The exposed portion is exposed so as to form an electrostatic latent image on the image carrier. The developing unit develops the electrostatic latent image on the image carrier into a toner image. The primary transfer unit transfers the toner image on the image carrier to the intermediate transfer body. The secondary transfer unit transfers the toner image on the intermediate transfer body to the recording medium. The cleaning mechanism removes residual toner on the intermediate transfer body. The control unit predicts that when the intermediate transfer body rotates in the forward direction, the arrival of the recording medium at the secondary transfer unit is delayed from the arrival of the toner image at the secondary transfer unit. Occasionally, by rotating the intermediate transfer body in the reverse direction, the toner image on the intermediate transfer body is controlled to be removed by the cleaning mechanism.

According to the image forming apparatus according to the present invention, it is possible to provide an image forming apparatus with improved productivity.

It is a figure which shows an example of the image forming apparatus which concerns on embodiment of this invention. It is a block diagram which shows an example of the circuit structure of an image forming apparatus. It is a flowchart which shows an example of the operation of a control part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description is not repeated. In the present specification, the X-axis and the Y-axis are parallel to the horizontal plane, and the Z-axis is parallel to the vertical line.

The image forming apparatus 100 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an example of an image forming apparatus 100.

The image forming apparatus 100 shown in FIG. 1 is a copying machine, a printer, a facsimile, or a multifunction device having these functions. Hereinafter, the image forming apparatus 100 will be described as a copying machine, but the present invention is not limited thereto.

The image forming apparatus 100 includes an image reading unit 170, an image forming unit 180, a control unit 10, and a storage unit 50. The image forming apparatus 100 further includes a paper feed unit 120, a paper feed roller 21, a feed roller 22, a retard roller 23, a transport roller to 24, an intermediate roller to 31, a resist roller to 41, a paper feed sensor S1, and a resist sensor S2. Be prepared. The image forming unit 180 includes a toner replenishing unit 140, an image forming unit 130, a fixing unit 110, a sheet conveying unit 160, and a sheet discharging unit 150. The image forming unit 180 forms an image on the sheet P based on the image data read by the image reading unit 170. Sheet P corresponds to an example of a "recording medium". The paper feed sensor S1 corresponds to an example of the “first detection unit”. The resist sensor S2 corresponds to an example of the "second detection unit".

A sheet P for printing is loaded on the paper feed unit 120. When printing, the sheet P in the paper feed unit 120 passes through the paper feed roller 21, the feed roller 22, the retard roller 23, the transport roller to 24, the intermediate roller to 31 and the resist roller to 41, and then to the image forming unit 180. Will be transported to.

The paper feed roller 21 feeds the sheet P from the paper feed unit 120. The sheet P fed by the paper feed roller 21 is conveyed to the feed roller 22 and the retard roller 23. The feed roller 22 and the retard roller 23 face each other and are in pressure contact with each other. The feed roller 22 rotates and feeds the sheet P in the transport direction. When one sheet P is fed, the retard roller 23 is driven by the feed roller 22 to rotate. On the other hand, when a plurality of sheets P are overlapped and fed, the retard roller 23 rotates or stops in the direction opposite to the direction in which the sheets P are sent out, and the retard roller 23 comes from the sheet P in contact with the feed roller 22. Separate the other sheet P. As a result, one sheet P is fed out by the feed roller 22.

The transfer roller pair 24 and the intermediate roller pair 31 are provided between the paper feed roller 21 and the resist roller pair 41, and transfer toward the resist roller pair 41 with the sheet P delivered by the feed roller 22 and the retard roller 23 sandwiched between them. do. The resist roller pair 41 corrects the inclination of the sheet P that has come into contact with the resist roller pair 41 and stopped. Then, the resist roller pair 41 temporarily waits for the sheet P in order to synchronize the transfer timing with the transfer of the sheet P, and then sends the sheet P to the image forming unit 180 in accordance with the transfer timing.

The paper feed sensor S1 is provided on the downstream side of the paper feed roller 21 and on the upstream side of the paper feed roller pair 24 (between the paper feed roller 21 and the paper feed roller pair 24) with respect to the paper feed direction of the sheet P. The paper feed sensor S1 detects the presence or absence of the sheet P at the first detection position P1. The resist sensor S2 is provided on the upstream side of the resist roller pair 41 and the downstream side of the intermediate roller pair 31 (between the intermediate roller pair 31 and the resist roller pair 41) with respect to the transport direction of the sheet P. The resist sensor S2 detects the presence or absence of the sheet P at the second detection position P2.

The sheet P transported to the image forming unit 180 is transported in the transport direction along the transport path by the sheet transport section 160 so that the sheet P is discharged from the sheet discharge section 150 via the image forming section 130 and the fixing section 110. Will be done.

The image forming unit 130 forms a toner image on the sheet P. The image forming unit 130 includes a photoconductor drum 131, an exposure unit 134, a developing unit 132, and a transfer unit 133. The photoconductor drum 131 corresponds to an example of an “image carrier”.

An electrostatic latent image is formed on the photoconductor drum 131 by a laser from the exposed unit 134. This laser is irradiated based on the electronic signal of the original image generated by the image reading unit 170. The developing unit 132 has a developing roller 232. The developing roller 232 forms a toner image on the photoconductor drum 131 by supplying toner to the photoconductor drum 131 to develop an electrostatic latent image. Toner is replenished from the toner replenishment unit 140 to the developing unit 132.

The transfer unit 133 transfers the toner image formed on the photoconductor drum 131 to the sheet P. The transfer unit 133 includes an intermediate transfer belt 251, a primary transfer roller 255, a secondary transfer roller 252, a drive roller 253, an opposing roller 254, and a cleaning mechanism 256. The intermediate transfer belt 251 corresponds to an example of an "intermediate transfer body". The primary transfer roller 255 corresponds to an example of the “primary transfer unit”. The secondary transfer roller 252 corresponds to an example of the “secondary transfer unit”.

The intermediate transfer belt 251 is an endless belt. The opposing roller 254 is arranged at a distance from the drive roller 253 in the positive direction of the Y axis so that the intermediate transfer belt 251 is stretched. The intermediate transfer belt 251 rotates, for example, along the forward rotation direction D. The forward rotation direction D is a direction in which the X axis facing the forward direction rotates counterclockwise.

The primary transfer roller 255 is arranged to face the photoconductor drum 131 via the intermediate transfer belt 251. When the primary transfer roller 255 presses against the photoconductor drum 131, the toner image formed on the surface of the photoconductor drum 131 is transferred to the outer peripheral surface of the intermediate transfer belt 251.

Toner images of, for example, Y (yellow), C (cyan), M (magenta), and B (black) colors are sequentially transferred to the outer peripheral surface of the intermediate transfer belt 251. As a result, the intermediate transfer belt 251 carries a full-color toner image in the immediate vicinity of the secondary transfer roller 252.

The secondary transfer roller 252 is pressed against the drive roller 253 via the intermediate transfer belt 251. The toner image transferred to the intermediate transfer belt 251 is transferred to the sheet P as it passes between the secondary transfer roller 252 and the drive roller 253.

The cleaning mechanism 256 removes residual toner on the intermediate transfer belt 251. The cleaning mechanism 256 is arranged, for example, in the vicinity of the opposing roller 254. That is, the cleaning mechanism 256 is arranged at a position where the intermediate transfer belt 251 is rotated by about half a circumference starting from the position of the secondary transfer roller 252.

The fixing portion 110 heats and pressurizes the sheet P by the fixing member 111 and the pressurizing member 112 to melt the unfixed toner image formed in the image forming portion 130 and fix it on the sheet P.

The control unit 10 includes a processor such as a CPU (Central Processing Unit). The storage unit 50 includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a hard disk drive, and stores data and computer programs. The processor of the control unit 10 controls each configuration of the image forming apparatus 100 by executing a computer program stored in the storage unit 50.

Next, the circuit configuration of the image forming apparatus 100 will be described with reference to FIGS. 1 and 2. FIG. 2 is a block diagram showing an example of the circuit configuration of the image forming apparatus 100.

As shown in FIG. 2, the image forming apparatus 100 further includes a drive circuit 60 and a motor 70. The control unit 10 controls the motor 70 via the drive circuit 60. The motor 70 drives the intermediate transfer belt 251 via the drive roller 253. The intermediate transfer belt 251 can rotate not only in the forward rotation direction D but also in the reverse rotation direction according to the control by the control unit 10.

The control unit 10 receives the detection result of the paper feed sensor S1 and the detection result of the resist sensor S2. The control unit 10 can calculate the linear velocity related to the transport of the sheet P based on the detection result of the paper feed sensor S1 and the detection result of the resist sensor S2. Further, the control unit 10 controls so that the paper feeding starts after a predetermined time has elapsed from the start of image drawing based on the design value of the linear velocity. However, for example, when the paper feed roller 21 is worn, the sheet P tends to slip. As a result, the arrival of the sheet P on the secondary transfer roller 252 may be delayed from the arrival of the toner image on the secondary transfer roller 252.

Therefore, when the intermediate transfer belt 251 rotates in the forward rotation direction D, the control unit 10 delays the arrival of the sheet P on the secondary transfer roller 252 from the arrival of the toner image on the secondary transfer roller 252. Is predicted or not, and the delay amount is predicted. The delay prediction is performed based on the detection result of the paper feed sensor S1 and the detection result of the resist sensor S2.

Next, the operation of the control unit 10 will be described with reference to FIGS. 1 to 3. FIG. 3 is a flowchart showing an example of the operation of the control unit 10.

Step S101: As shown in FIG. 3, the control unit 10 determines whether or not a paper feed delay to the secondary transfer roller 252 is predicted. Specifically, the control unit 10 predicts the paper feed delay based on the detection result of the paper feed sensor S1. Then, the control unit 10 predicts the delay amount from the linear velocity of the sheet P calculated based on the detection result of the paper feed sensor S1 and the detection result of the resist sensor S2. If a paper feed delay is predicted (Yes in step S101), the process of the control unit 10 proceeds to step S103. If the paper feed delay is not predicted (No in step S101), the process of the control unit 10 proceeds to step S115.

Step S103: The control unit 10 determines whether or not the sheet P for which the paper feed delay is predicted is the second or subsequent sheet of continuous printing. When the sheet P is the second and subsequent sheets of continuous printing (Yes in step S103), the process of the control unit 10 proceeds to step S113. When the sheet P is the first sheet of continuous printing (No in step S103), the process of the control unit 10 proceeds to step S105.

Step S105: The control unit 10 stops the image drawing by the image forming unit 130 in the middle. When the process of step S105 is completed, the process of the control unit 10 proceeds to step S107.

Step S107: The control unit 10 switches so that the intermediate transfer belt 251 rotates in the reverse rotation direction. When the process of step S107 is completed, the process of the control unit 10 proceeds to step S109.

Step S109: The control unit 10 controls so that the toner image in the process of image formation on the intermediate transfer belt 251 is removed by the cleaning mechanism 256. When the process of step S109 is completed, the process of the control unit 10 proceeds to step S111.

Step S111: The control unit 10 switches so that the intermediate transfer belt 251 rotates in the forward rotation direction D. After that, the process of the control unit 10 proceeds to step S115. As a result, the image is executed again. In order to match the timing when the toner image to be recreated arrives at the secondary transfer roller 252 and the timing when the sheet P for which the paper feed delay is expected arrives at the secondary transfer roller 252, the control unit 10 sets the sheet P. It may be stopped by the resist roller vs. 41.

Step S113: When the sheet P for which the paper feed delay is predicted is the second and subsequent sheets of continuous printing, the delay amount of the paper feed delay is already known. Therefore, the control unit 10 controls so that the timing at which the exposure unit 134 starts forming an electrostatic latent image on the photoconductor drum 131 is delayed by a time equal to the delay amount. After that, the process of the control unit 10 proceeds to step S115. As a result, the reverse rotation control of the intermediate transfer belt 251 becomes unnecessary for the second and subsequent sheets of continuous printing.

Step S115: The control unit 10 determines whether or not the job has been completed. When the job is completed (Yes in step S115), the processing of the control unit 10 is completed. If the job is not completed (No in step S115), the process of the control unit 10 returns to step S101.

According to the embodiment, when a delay in feeding paper to the secondary transfer roller 252 is predicted, the intermediate transfer belt so that the toner image in the middle of image formation on the intermediate transfer belt 251 is removed by the cleaning mechanism 256. The 251 is controlled to rotate in the reverse direction. Since the paper feed delay can be predicted at the initial stage of a series of printing operations called the detection timing of the paper feed sensor S1, the cleaning by the reverse rotation control of the intermediate transfer belt 251 can be completed in a shorter time, and the image forming apparatus can be completed. The productivity of 100 is improved.

During the reverse rotation period of the intermediate transfer belt 251, the secondary transfer roller 252 may be retracted from the intermediate transfer belt 251 so that the influence of the residual toner on the intermediate transfer belt 251 is alleviated.

The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various embodiments without departing from the gist thereof. The drawings are schematically shown mainly for each component for easy understanding, and the thickness, length, number, etc. of each component shown are different from the actual ones for the convenience of drawing creation. .. Further, the material, shape, dimensions, etc. of each component shown in the above embodiment are merely examples, and are not particularly limited, and various changes can be made without substantially deviating from the effects of the present invention. be.

The present invention can be used in the field of image forming apparatus.

10 Control unit 100 Image forming device 130 Image forming unit 131 Photoreceptor drum (image carrier)
132 Development unit 133 Transfer unit 134 Exposure unit 180 Image formation unit 251 Intermediate transfer belt (intermediate transfer body)
252 Secondary transfer roller (secondary transfer section)
255 Primary transfer roller (Primary transfer unit)
256 Cleaning mechanism D Forward rotation direction P sheet (recording medium)
P1 1st detection position P2 2nd detection position S1 Paper feed sensor (1st detection unit)
S2 resist sensor (second detector)

Claims (4)

An image forming apparatus that transports a recording medium along a transport path and forms an image on the recording medium.
Image carrier and
An endless belt-shaped intermediate transfer member and
An exposed portion that is exposed so as to form an electrostatic latent image on the image carrier, and an exposed portion.
A developing unit that develops the electrostatic latent image on the image carrier into a toner image, and
A primary transfer unit that transfers the toner image on the image carrier to the intermediate transfer body, and
A secondary transfer unit that transfers the toner image on the intermediate transfer body to the recording medium, and
A cleaning mechanism that removes residual toner on the intermediate transfer member,
When the intermediate transfer body rotates in the forward direction and the arrival of the recording medium at the secondary transfer unit is predicted to be delayed from the arrival of the toner image at the secondary transfer unit, the intermediate transfer is performed. An image forming apparatus including a control unit that controls the toner image on the intermediate transfer body to be removed by the cleaning mechanism by rotating the body in the reverse direction. The image forming apparatus according to claim 1, wherein the cleaning mechanism is arranged at a position where the intermediate transfer body is rotated by half a circumference starting from the position of the secondary transfer portion. A first detection unit that detects the presence or absence of the recording medium at the first detection position on the transport path, and
Further provided with a second detection unit for detecting the presence or absence of the recording medium at the second detection position located on the downstream side of the first detection position and on the upstream side of the secondary transfer unit on the transport path.
The image forming according to claim 1 or 2, wherein the control unit predicts the presence or absence of the delay and the delay amount based on the detection result of the first detection unit and the detection result of the second detection unit. Device. After the delay amount is predicted, the control unit delays the timing of starting image formation in which the exposure unit forms the electrostatic latent image on the image carrier by a time equal to the delay amount. The image forming apparatus according to claim 3.

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