JP2019003078A - Image forming apparatus and control method - Google Patents

Abstract

To accurately prevent displacement of an image position with respect to a sheet.SOLUTION: An image forming apparatus 100 comprises a position detection sensor 62 that is arranged downstream of a secondary transfer roller 9 and upstream of a fixing device 50, and detects the position of a side end part of a sheet P. A control unit 11 controls swinging of a registration roller 27 on the basis of a result of detection performed by the position detection sensor 62. For example, the control unit determines swinging control information on the registration roller 27 on the basis of a result of detection performed by the position detection sensor 62, and controls swinging of the registration roller 27 on the basis of the determined swinging control information.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an image forming apparatus and a control method.

  In recent years, multifunctional image forming apparatuses having functions such as printers, scanners, copiers, and fax machines have been widely used. In an image forming apparatus, paper is transported from a paper feed unit or a reverse path to a transfer unit during image formation. (There is also a case of direction). When the printing process is performed in such a state where the paper is misaligned, there is a problem that the image forming position on the paper is deviated from the original proper position.

Therefore, in order to accurately align the image and the paper in consideration of the deviation of the paper, the registration rocking that corrects the deviation of the paper by sandwiching the paper with the registration roller and swinging in the paper width direction is performed. Dynamic correction is performed.
For example, in Patent Document 1, a registration roller is disposed on the upstream side of the secondary transfer roller, and a line sensor is disposed on the downstream side of the registration roller and on the upstream side of the secondary transfer roller. An image forming apparatus that corrects a deviation of a sheet by swinging the sheet in the sheet width direction based on the position of the side edge of the sheet is disclosed.

  In Patent Document 2, a plurality of CISs are arranged downstream of the registration roller and upstream of the secondary transfer roller. Before the sheet enters the secondary transfer roller, the CIS is close to the registration roller side. , The registration roller is moved in the paper width direction based on the detection result, and during the transfer, the registration roller is moved based on the CIS detection result close to the secondary transfer roller. It is described that the position of is corrected.

JP 2013-91563 A JP 2014-133634 A

  However, as in Patent Document 1 and Patent Document 2, the position of the paper side end before passing through the secondary transfer roller is detected, and the registration roller is swung based on the detection result, thereby the paper side end. Even if these positions are aligned, it is not possible to suppress the shift of the sheet that occurs after the position of the sheet side edge is detected or after the registration roller swings. Therefore, the image position with respect to the paper may be shifted.

  An object of the present invention is to suppress a deviation of an image position with respect to a sheet with high accuracy.

In order to solve the above-mentioned problem, the invention described in claim 1
A transfer section for transferring an image to paper;
A fixing unit for fixing the image transferred by the transfer unit to the paper;
In an image forming apparatus comprising:
A swing roller configured by a pair of rollers for transporting the paper being transported toward the transfer unit;
A detection unit that is disposed downstream of the transfer unit and upstream of the fixing unit and detects a position of a side edge of the sheet;
A control unit that performs swing control of the swing roller based on a detection result by the detection unit;
Is provided.

The invention according to claim 2 is the invention according to claim 1,
The control unit determines swing control information of the swing roller based on a detection result by the detection unit, and performs swing control of the swing roller based on the determined swing control information.

The invention according to claim 3 is the invention according to claim 2,
The detection unit is disposed on the side of the sheet on which the image is transferred, detects the position of the side edge of the sheet and the position of the image on the sheet,
The control unit determines the swing control information based on the position of the side edge of the sheet detected by the detection unit and the position of the image on the sheet.

The invention according to claim 4 is the invention according to claim 2 or 3,
The control unit further determines the swing control information according to a condition related to paper conveyance.

The invention according to claim 5 is the invention according to any one of claims 2 to 4,
The control unit determines the swing control information for each of a plurality of timings at which the swing roller is swung based on a detection result by the detection unit.

The invention according to claim 6 is the invention according to any one of claims 1 to 5,
A second detection unit that is disposed upstream of the swing roller and detects a position of a side edge of the paper;
The control unit further performs swing control of the swing roller based on a detection result of the second detection unit.

The invention according to claim 7 is the invention according to any one of claims 1 to 6,
A third detection unit that is disposed downstream of the swing roller and upstream of the transfer unit and detects a position of a side edge of the paper;
The control unit further performs swing control of the swing roller based on a detection result of the third detection unit.

The invention according to claim 8 is the invention according to any one of claims 1 to 7,
A fourth detection unit that is disposed downstream of the fixing unit and detects a position of a side edge of the paper;
The control unit further performs swing control of the swing roller based on a detection result of the fourth detection unit.

The invention according to claim 9 is the invention according to any one of claims 1 to 8,
The swing roller swings in a direction orthogonal to the paper transport direction.

The invention according to claim 10 is:
A transfer section for transferring an image to paper;
A fixing unit for fixing the image transferred by the transfer unit to the paper;
A swing roller configured by a pair of rollers for transporting the paper being transported toward the transfer unit;
A control method of a swing roller in an image forming apparatus comprising:
Based on the detection result of the detection unit that is disposed downstream of the transfer unit and upstream of the fixing unit and detects the position of the side edge of the sheet, the swing control of the swing roller is performed.

  According to the present invention, it is possible to suppress the displacement of the image position with respect to the sheet with high accuracy.

1 is a configuration diagram schematically illustrating an image forming apparatus according to an embodiment. It is the figure which looked at the arrangement | positioning of a position detection sensor, and the rocking | fluctuation process of the paper by a registration roller from the upper surface. It is a figure which shows arrangement | positioning of a position detection sensor and a suction fan. FIG. 2 is a block diagram schematically showing a configuration of a control system of the image forming apparatus in FIG. 1. It is a flowchart which shows the rocking | swiveling control process A performed by the control part of FIG. 4 in 1st Embodiment. It is a figure which shows an example of a sub scanning curve. It is a figure which shows an example of a rocking | fluctuation control table. It is a flowchart which shows the rocking | swiveling control process B performed by the control part of FIG. 4 in 2nd Embodiment. It is a figure which shows the example of arrangement | positioning of a position detection sensor. It is a figure which shows the example of arrangement | positioning of a position detection sensor. It is a figure which shows the example of arrangement | positioning of a position detection sensor.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

<First Embodiment>
[Configuration of Image Forming Apparatus 100]
First, the configuration of the image forming apparatus 100 according to the first embodiment will be described.
FIG. 1 is a configuration diagram schematically illustrating an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 is an electrophotographic image forming apparatus 100 such as a copying machine, and forms a full-color image by arranging a plurality of photoconductors facing one intermediate transfer belt in the vertical direction. This is a so-called tandem color image forming apparatus.

  The image forming apparatus 100 is mainly composed of a document reading device SC, an image forming unit 10, a fixing device 50, and a control unit 11, and these are housed in one casing.

  The document reader SC scans and exposes an image of the document with the optical system of the scanning exposure device, reads the reflected light with a line image sensor, and obtains an image signal. This image signal is subjected to processing such as A / D conversion, shading correction, and compression, and then input to the control unit 11 as image data. Note that the image data input to the control unit 11 is not limited to the data read by the document reading device SC. For example, the image data is received from a personal computer connected to the image forming device 100 or another image forming device by the communication unit 13. It may be what you did.

  The image forming unit 10 includes four sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 6, a secondary transfer roller 9, and the like. The image forming units 10Y, 10M, 10C, and 10K are an image forming unit 10Y that forms a yellow (Y) image, an image forming unit 10M that forms a magenta (M) image, and an image that forms a cyan (C) image. The forming unit 10C includes an image forming unit 10K that forms a black (K) image.

  The image forming unit 10Y includes a photosensitive drum 1Y and a charging unit 2Y, an optical writing unit 3Y, a developing device 4Y, and a drum cleaner 5Y arranged around the photosensitive drum 1Y. Similarly, the image forming units 10M, 10C, and 10K include the photosensitive drums 1M, 1C, and 1K and charging units 2M, 2C, and 2K, optical writing units 3M, 3C, and 3K, and developing devices 4M, arranged around the photosensitive drums 1M, 1C, and 1K. 4C, 4K and drum cleaners 5M, 5C, 5K.

  The surfaces of the photosensitive drums 1Y to 1K are uniformly charged by the charging units 2Y to 2K, and latent images are formed on the photosensitive drums 1Y to 1K by scanning exposure by the optical writing units 3Y to 3K. Is done. Further, the developing devices 4Y to 4K develop latent images on the photosensitive drums 1Y to 1K by developing with toner. Thereby, a toner image of a predetermined color corresponding to any one of yellow, magenta, cyan, and black is formed on the photosensitive drums 1Y to 1K. The toner images formed on the photosensitive drums 1Y to 1K are sequentially transferred to predetermined positions on the rotating intermediate transfer belt 6 by primary transfer rollers 7Y, 7M, 7C, and 7K.

  The toner image composed of each color transferred onto the intermediate transfer belt 6 is transferred by the secondary transfer roller 9 to the paper P conveyed at a predetermined timing by a paper conveyance unit 20 described later. The secondary transfer roller 9 is a pressure contact member that forms a nip portion (hereinafter referred to as “transfer nip portion”) by being disposed in pressure contact with the intermediate transfer belt 6.

  The paper transport unit 20 transports the paper P along the transport path of the paper P. The paper P is stored in the paper feed tray 21, and the paper P stored in the paper feed tray 21 is taken in by the paper feed unit 22 and sent out to the transport path. Alternatively, the paper P is stored in a paper feed tray included in an external paper feed device (not shown) connected to the image forming apparatus 100 via the external paper feed ports 81 and 82 and the like. The held paper P is supplied from the paper supply device to the image forming apparatus 100 via the external paper supply port 81 or 82 and is sent out to the conveyance path. For example, the long paper is supplied from the external paper feeder to the image forming apparatus 100 via the external paper feed port 81 or 82.

  In this transport path, a plurality of transport means for transporting the paper P is provided upstream of the transfer nip portion. Each of the conveying means is composed of a pair of pressure-contacted rollers, and conveys the paper P when at least one of the rollers is rotationally driven through a driving mechanism mainly composed of an electric motor. In addition, the pair of rollers constituting the individual conveying means is configured so that the state between the rollers can be switched between a pressure contact state and a separated state.

  In the present embodiment, intermediate conveyance rollers 23 to 25, a loop roller 26, and a registration roller 27 are provided as conveyance means from the upstream side to the downstream side of the conveyance path of the paper P. In addition to the configuration of the pair of rollers, the conveyance unit can widely employ a configuration including a pair of rotating members such as a combination of belts or a combination of a belt and a roller.

  In such a transport path, the paper P fed from the paper feed tray 21 or the paper feed tray of the paper feeder is fed by a plurality of intermediate transport rollers 23 to 25 and a loop roller 26 provided from the upstream side to the downstream side. It is sequentially transported and travels along the transport path. When the leading edge of the paper P approaches the registration roller 27, the paper P conveyed by the loop roller 26 and the like is abutted against the registration roller 27 in a rotation stopped state, and the loop roller 26 continues to rotate for a predetermined time. As a result, a loop is formed on the paper P. By this loop forming action, the bending of the leading edge of the paper P is corrected (skew correction).

  Next, when the registration roller 27 starts rotating at a predetermined timing so as to synchronize with the toner image carried by the intermediate transfer belt 6, the intermediate transport rollers 23 to 25 and the loop roller 26 are switched from the pressure contact state to the separated state. It is done. That is, after the loop roller 26 transitions to the separated state, the paper P is conveyed only by the registration roller 27. The registration roller 27 performs a swinging process, which will be described later, while transporting the paper P as a swinging roller, to the transfer nip portion of the intermediate transfer belt 6 as an image carrier and the secondary transfer roller 9 as a transfer portion. And the paper P are conveyed.

  As shown in FIG. 2, the registration roller 27 is configured to be swingable in the sheet width direction CD (direction perpendicular to the sheet conveyance direction (sub-scanning direction) FD). A driving mechanism 34 mainly composed of an electric motor (for example, a stepping motor) is coupled to the registration roller 27, and is driven by the driving mechanism 34, whereby the sheet width direction CD starts from a predetermined home position. Can be moved to.

  The registration rollers 27 move the conveyed paper P along the paper width direction CD by moving along the paper width direction CD in accordance with the passage period during which the paper P passes through the registration roller 27 (oscillation process). Thereby, the registration roller 27 adjusts the transport position of the paper P in the paper width direction CD so as to be aligned with the position of the transferred toner image.

  A registration sensor 61 is disposed between the registration roller 27 and the loop roller 26 in the conveyance path. The registration sensor 61 detects the arrival of the leading edge of the paper P at the detection position of the registration sensor 61 (a position that is a predetermined distance before the registration roller 27). The detection result of the registration sensor 61 is used for detecting the rotation start timing of the registration roller 27 and the like.

  As shown in FIGS. 2 and 3, a position detection sensor 62 is provided on the image surface side of the sheet P downstream of the secondary transfer roller 9 and upstream of the fixing device 50. The position detection sensor 62 includes, for example, a linear image sensor (for example, a CCD line sensor) in which a plurality of light receiving elements are linearly arranged along the paper width direction CD, an optical system, a light source, and the like. The position detection sensor 62 is a detection unit that detects the position in the sheet width direction CD of the side edge of the sheet P after the toner image is transferred by the secondary transfer roller 9. In the present embodiment, since the position detection sensor 62 can read the paper P from the image surface side, the position detection sensor 62 can detect the image position of the toner image transferred to the paper P. The detection result of the position detection sensor 62 is output to the control unit 11 and used for determining the swing control information of the registration roller 27 in the swing process.

  As shown in FIG. 3, a suction fan 70 is provided below the conveyance path that faces the position detection sensor 62. For example, since the paper P can be made to follow the lower guide by providing a vent hole or the like in the lower guide (conveyor belt) of the transport path and sucking with the suction fan 70, the toner on the paper P adheres to the position detection sensor 62 Can be prevented. Further, the position detection sensor 62 can be disposed in the vicinity of the image plane, and the detection accuracy can be improved.

  The fixing device 50 is a device that performs a fixing process on the paper P on which the toner image is transferred, that is, the paper P sent out from the transfer nip portion. For example, the fixing device 50 includes a pair of fixing members (eg, a pair of rollers) It is comprised with the heater which heats one or both of the members. The fixing device 50 fixes the toner image onto the paper P through the action of the pressure applied by the pair of fixing members and the heat of the fixing member in the conveyance process of the paper P.

  The paper P subjected to the fixing process by the fixing device 50 is discharged by a paper discharge roller 28 to a paper discharge tray 29 attached to the outer side surface of the housing. When image formation is also performed on the back surface of the paper P, the paper P on which image formation on the paper surface has been completed is conveyed by the switching gate 30 to the reverse roller 31 below. The reversing roller 31 pinches the rear end of the conveyed paper P, reverses the paper P by reverse feeding, and sends it out to the refeed conveyance path. The paper P sent out to the paper re-feed transport path is transported by a plurality of paper re-feeding transport means, and the paper P is returned to the transfer nip portion via the registration roller 27. The paper discharge roller 28, the switching gate 30, the reversing roller 31, and the refeeding transport means also constitute the paper transport unit 20 described above.

  As shown in FIG. 4, the control unit 11 includes a storage unit 12, a communication unit 13, an operation unit 14, a document reading device SC, an image forming unit 10, a paper transport unit 20, a fixing device 50, a registration sensor 61, and a position detection sensor. 62, connected to the environment sensor 63 and the like. The control unit 11 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the control unit 11 reads the system program and various processing programs stored in the storage unit 12 and expands them in the RAM, and centrally controls the operations of the respective units of the image forming apparatus 100 according to the expanded programs. For example, when a job execution command is input from the operation unit 14, the control unit 11 executes a job and forms a toner image on the paper P based on image data input by the document reading device SC or the communication unit 13. Take control. Further, when a job execution command is input from the operation unit 14, the control unit 11 executes a swing control process A described later, and performs swing control of the registration roller 27 during job execution.

  The storage unit 12 is configured by a nonvolatile semiconductor memory, an HDD (Hard Disk Drive), or the like, and stores various programs executed by the control unit 11 as well as parameters and data necessary for each unit.

  The communication unit 13 includes various interfaces such as a NIC (Network Interface Card), a MODEM (Modulator-DEModulator), and a USB (Universal Serial Bus), and connects to an external device.

  The operation unit 14 outputs various information set by the user to the control unit 11. As the operation unit 14, for example, a touch panel capable of performing an input operation according to information displayed on the display can be used. Through the operation unit 14, the user can set the printing conditions, that is, the paper type, basis weight, size, paper feed tray to be used, image density, magnification, presence / absence of duplex printing, and the like. Further, the user can input a job execution command and an operation instruction in the adjustment mode through the operation unit 14. The control unit 11 can display various messages to the user via the operation unit 14 by controlling the operation unit 14.

  The environment sensor 63 includes, for example, a temperature sensor and a humidity sensor, detects the temperature and humidity in the housing of the image forming apparatus 100, and outputs the detection result to the control unit 11.

[Operation of Image Forming Apparatus 100]
Next, the operation of the image forming apparatus 100 in the first embodiment will be described.
FIG. 5 is a flowchart showing a swing control process A for controlling the swing operation of the registration roller 27. The processing shown in this flowchart is executed in cooperation with the program stored in the control unit 11 and the storage unit 12 in accordance with a job execution command from the user.

When the job is started, the control unit 11 waits for the position detection sensor 62 to detect the leading edge of the paper P (step S1).
When the leading edge of the paper P is detected by the position detection sensor 62 (step S1; YES), the control unit 11 detects the position of the side edge of the paper P at a plurality of positions (eg, two points) by the position detection sensor 62. A result is acquired (step S2).

  Next, the control unit 11 determines the swing control information of the registration roller 27 at each predetermined swing timing based on the detection result by the position detection sensor 62 (step S3). Here, the swing timing is a timing at which the registration roller 27 is swung. In the present embodiment, for example, a plurality of swing timings (for example, at substantially equal intervals) in advance, such as t1 seconds after the timing when the position detection sensor 62 detects the leading edge of the paper P, t2 seconds later,. It has been decided.

  Here, for example, misalignment of the fixing roller of the registration roller 27, the secondary transfer roller 9, and the fixing device 50, and the difference in roller diameter between the front side and the back side of each roller when the image forming apparatus is viewed from the front. For example, as shown in FIG. 6, after entering the registration roller 27, there may occur a sub-scanning curve in which the paper P is bent in the middle. As a result, the position of the paper P shifts with respect to the transfer position by the secondary transfer roller 9, and the toner image is the optimum position (referred to as the optimum image position. For example, the center in the width direction of the paper P and the width direction of the toner image. Is not transferred to the position where the center of the line coincides). Therefore, in this embodiment, the position detection sensor 62 provided downstream of the secondary transfer roller 9 detects the actual position of the side edge of the sheet P after transfer, and the registration roller 27 swings based on the detection result. By determining the amount of movement and the like and swinging the registration roller 27, the position of the side edge of the paper P is adjusted, and the deviation of the position of the paper P from the transfer position is suppressed. For example, in the case shown in FIG. 6, the registration roller 27 is swung in the direction of the arrow.

  In step S <b> 3, for example, the control unit 11 acquires and acquires the detection results of the positions of the sheet side end portions (X <b> 1 and X <b> 2) by the position detection sensor 62 at two points in the sub-scanning direction on the leading end side of the sheet P. Based on the detected result, the inclination of the paper P is calculated. Then, based on the calculated inclination, the amount of deviation from the target position of the sheet side edge at each swing timing is calculated, and based on the calculated shift amount, swing control information (swing amount, Determine the rocking direction and rocking speed. The target position is a position where the toner image is expected to be transferred to the optimum image position with respect to the paper P if the side edge of the paper P passes through the position. Since the position of the registration roller 27 is known from the roller position of the stepping motor of the drive mechanism 34, the control unit 11 determines the swing control information based on the detection result by the position detection sensor 62 and the position information of the registration roller 27. It is good as well.

The inclination of the paper P can be calculated by the following equation, for example.
Inclination of paper P = (difference in the paper width direction between X1 and X2) / (transport distance between X1 and X2)
Further, the swing amount can be calculated by the following equation, for example.
Swing amount = Deviation amount from the target position at the paper side edge x α
Here, α is a coefficient. The transport state of the paper P differs depending on the paper transport conditions, for example, the paper type, basis weight, environment (temperature, humidity, etc.), paper size (paper width, paper length), etc. of the paper P. It is preferable that the value varies depending on the conditions related to the sheet conveyance and the swing timing (that is, the position in the sub-scanning direction to be swung). Further, it is preferable to increase the swing speed as the swing amount increases.

  Since the position detection sensor 62 can acquire the image information of the toner image, the swing detection information of the registration roller 27 is obtained based on the detection result of the position of the paper side edge and the position of the toner image by the position detection sensor 62. You may decide. For example, based on the detection result of the position of the paper side edge and the position of the toner image at a plurality of points detected by the position detection sensor 62, the distance and inclination of the paper side edge and the toner image at the plurality of points are calculated and calculated. Based on the measured distance and inclination, the distance between the paper side edge and the toner image at each swing timing is calculated. Then, the difference (deviation amount) between the calculated distance and the distance between the sheet side edge when the toner image is placed at the optimum image position and the toner image is calculated, and each swing is calculated based on the calculated deviation amount. The swing control information at the timing is determined. Thereby, the toner image can be aligned with the optimum image position with higher accuracy.

  Next, the control unit 11 waits for the swing timing of the registration roller 27 to arrive (step S4). When it is determined that the swing timing has arrived (step S4; YES), the control unit 11 causes the drive mechanism 34 to move the registration roller 27 based on the swing control information determined in step S3 according to the swing timing. Swing (step S5).

  Next, the control unit 11 determines whether or not the swing at the final swing timing is finished (step S6). For example, based on the paper size of the paper P, the elapsed time after the position detection sensor 62 detects the leading edge of the paper P, and the conveyance speed, it is determined whether or not the swing at the final swing timing has ended. .

  When it is determined that the swing at the final swing timing has not been completed (step S6; NO), the control unit 11 returns to step S4, waits for the next swing timing, and the swing timing has arrived. Then, the process of swinging the registration roller 27 is repeated.

When it is determined that the swing at the final swing timing has been completed (step S6; YES), the control unit 11 determines whether the transfer to the final page has been completed (step S7).
If it is determined that the transfer to the last page has not been completed (step S7; NO), the control unit 11 returns to step S1.
When it is determined that the transfer to the last page has been completed (step S7; YES), the control unit 11 ends the swing control process A.

  As described above, in the first embodiment, the position detection sensor 62 is provided downstream of the secondary transfer roller 9, and the detection result of the position detection sensor 62 on the leading end side of the sheet P (the position of the sheet side end and / or the toner). Based on the image position), the swing of the registration roller 27 on the rear end side of the paper P is controlled. Therefore, the position of the side edge of the paper P can be adjusted by swinging the registration roller 27 based on the deviation of the position of the side edge of the actual paper P after the transfer from the target position. The deviation of the toner image position with respect to the paper P due to the bending can be suppressed with high accuracy. In particular, it is more effective when the paper is long in the paper conveyance direction, such as long paper.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
In the second embodiment, an example will be described in which the swing control information of the registration roller 27 after the next sheet is determined based on the detection result of the position detection sensor 62 provided downstream of the secondary transfer roller 9.

In the second embodiment, the storage unit 12 stores a swing control table 121 in addition to various programs executed by the control unit 11 and parameters and data necessary for each unit.
The swing control table 121 is a table in which swing control information for controlling the swing operation of the registration roller 27 is stored. The swing control table 121 includes swing control information (here, swing amount, swing direction, swing speed) corresponding to a plurality of swing timings (timing 1 to n) at which the registration roller 27 is swing controlled. Are stored. In the present embodiment, the swing timing is determined so as to swing from the leading edge to the trailing edge of the paper P at substantially equal intervals.
Here, the state when the paper P is transported is a condition related to the paper transport, such as the paper type, basis weight, environment (temperature, humidity, etc.), paper size (paper width, paper length), etc. Therefore, in order to accurately write the toner image at the optimum image position on the paper P, it is preferable that the swing control table 121 stores swing control information according to the conditions related to the sheet conveyance. .
FIG. 7 is a diagram illustrating an example of the swing control table 121. FIG. 7 shows, as an example, a swing control table 121 that stores swing control information used at each swing timing (timing 1 to n) for each paper type.

Further, the storage unit 12 of the second embodiment stores a program for executing a swing control process B described later.
Since the configuration of the other second embodiment is the same as that described in the first embodiment, the description will be cited and the operation in the second embodiment will be described below.

  FIG. 8 is a flowchart showing the swing control process B of the registration roller 27 executed by the control unit 11 in the second embodiment. The processing shown in this flowchart is executed in cooperation with the program stored in the control unit 11 and the storage unit 12 in accordance with a job execution command from the user.

  When the job is started, the control unit 11 waits for the swing timing of the registration roller 27 to arrive (step S11). In this embodiment, the swing timing is determined by the elapsed time after the registration sensor 61 detects the leading edge of the paper P, and the control unit 11 detects the leading edge of the paper P. It is determined whether or not the swing timing has arrived based on the elapsed time since.

  When it is determined that the swing timing has arrived (step S11; YES), the control unit 11 is based on the swing control information that is specified by the swing control table 121 and that corresponds to the swing timing and the conditions related to paper conveyance. Then, the registration roller 27 is swung by the drive mechanism 34 (step S12).

  The control unit 11 repeatedly executes steps S11 to S13 until the registration roller 27 swings at the final swing timing, and swings the registration roller 27 at each swing timing. If the sheet P reaches the position detection sensor 62 during this time, the position detection sensor 62 acquires image information indicating the position of the sheet side edge and the position of the toner image for each line, for example, and outputs the image information to the control unit 11. To do.

  When it is determined that the swing of the registration roller 27 at the final swing timing has been completed (step S13; YES), the control unit 11 obtains a detection result by the position detection sensor 62 at a position corresponding to each swing timing. (Step S14). For example, the control unit 11 specifies the region of the paper P and the toner image region from the detection result (image information) by the position detection sensor 62, and the paper P at the position corresponding to each swing timing of the paper P in the sub-scanning direction. The position of the side edge and the position of the toner image are acquired.

  Next, the control unit 11 calculates a correction value of the swing control information at each swing timing based on the acquired detection result by the position detection sensor 62 (step S15). For example, the control unit 11 determines the distance between the side edge of the sheet P and the position of the toner image at a position corresponding to each swing timing of the sheet P in the sub-scanning direction (position swung at each swing timing). get. Then, for example, the difference between the acquired distance and the distance between the side edge of the paper P when the toner image is written at the optimal image position and the toner image is calculated as a shift amount, and based on the calculated shift amount, The correction value of the swing control information at each swing timing is determined.

  And the control part 11 corrects rocking | fluctuation control information based on the correction value calculated about each rocking | fluctuation timing, and updates the rocking | fluctuation control table 121 (step S16). In other words, the swing control table 121 is stored in the storage unit 12 by overwriting the swing control information according to the swing timing of the swing control table 121 and the conditions related to the sheet conveyance with the swing control information corrected by the calculated correction value. Remember me.

  Here, when the sub-scanning curve occurs, the deviation of the image position with respect to the paper P tends to increase toward the rear end. In particular, the deviation becomes significant in a sheet that is long in the sheet conveyance direction, such as a long sheet. In the swing control process B, based on the detection results of the position of the side edge of the paper P and the position of the toner image by the position detection sensor 62 after the transfer, at each position in the sub-scanning direction corresponding to each swing timing. The amount of deviation of the positional relationship between the paper side edge and the toner image (the amount of deviation from the optimum positional relationship) is calculated, and the swing control information of the registration roller 27 at each swing timing is corrected based on the calculated shift amount. Since the swing control table 121 is updated, the swing control information can be individually corrected at each swing timing, and the displacement of the image position with respect to the sheet due to the sub-scan bend is suppressed with high accuracy after the next sheet. It becomes possible to do. In particular, it is more effective when the paper is long in the paper conveyance direction, such as long paper.

Next, the control unit 11 determines whether or not the transfer to the last page has been completed (step S17).
If it is determined that the transfer to the last page has not been completed (step S17; NO), the control unit 11 returns to step S11.
When it is determined that the transfer to the last page has been completed (step S17; YES), the control unit 11 ends the swing control process B.

  The swing control process B is a process of correcting the swing control information used for the subsequent swing control (after the next sheet) based on the swing operation of the registration roller 27 during the job execution. Reference numeral 100 has an adjustment mode. In the adjustment mode, the swing control information in the swing control table 121 can be set or corrected in advance before executing a job. For example, when an operation in the adjustment mode is instructed by the operation unit 14, the control unit 11 conveys a predetermined number of sheets from the sheet feeding tray 21 or the sheet feeding tray of the sheet feeding device, and is stored in the storage unit 12 in advance. An image is formed by the image forming units 10Y to 10K based on the image data being transferred, and the image is transferred to the paper by the secondary transfer roller 9. Further, the control unit 11 causes the registration roller 27 to swing and detect the side edge of the sheet onto which the image has been transferred and the position detection sensor 62 of the toner image by the same control as the swing control process B. Based on the detection result, the swing control information is set or corrected in the swing control table 121. As described above, since the image forming apparatus 100 has the adjustment mode, the swing control table 121 can be set or corrected in advance before the job is executed, and the shift between the sheet and the image position with respect to the first sheet is performed. Can be suppressed, and a print with good finish can be provided.

  Further, for example, in the second embodiment, every time an image for one page is transferred, the detection result of the position of the side edge portion of the paper P and the position of the toner image by the position detection sensor 62 is acquired. Although the case where the swing control information is corrected in real time based on the detection result has been described as an example, the calculation value (for example, the amount of deviation) of the detection result in a predetermined period (that is, a sheet on which a plurality of images are transferred) The swing control information may be corrected based on an average value, a median value, or the like. Thus, the swing control information can be efficiently corrected based on the tendency of the predetermined period.

  In the swing control process B, when the job is being executed, the swing control information used for swing control of the registration roller 27 on the next sheet is corrected based on the detection result by the position detection sensor 62 of the front sheet. However, the swing control information used for swing control of the registration roller 27 on the rear end side of the own paper may be corrected. For example, in the case of a sheet having a long sheet conveyance direction such as a long sheet, when the position detection sensor 62 detects the position of the side edge portion and the toner image up to a predetermined size, the control unit 11 performs the detection based on the detection result. The correction value of the swing control information may be calculated to correct the swing control information, and the registration roller 27 may be controlled on the rear end side of the own paper based on the corrected swing control information.

  In the swing control process B, the swing control information in the swing control table 121 is directly rewritten with the correction value calculated in step S15. A correction value table that stores correction values according to conditions may be provided. Then, the control unit 11 writes the correction value calculated in step S15 into the correction value table according to the swing timing and the conditions related to the sheet conveyance, and then performs the swing control when performing the swing control of the registration roller 27. The swing control of the registration roller 27 may be performed based on the swing control information based on the correction values in the table 121 and the correction value table.

As described above, the image forming apparatus 100 includes the position detection sensor 62 that is disposed downstream of the secondary transfer roller 9 and upstream of the fixing device 50 and detects the position of the side edge of the paper P. The unit 11 performs swing control of the registration roller 27 based on the detection result by the position detection sensor 62. For example, the swing control information of the registration roller 27 is determined based on the detection result of the position detection sensor 62, and the swing control of the registration roller 27 is performed based on the determined swing control information.
Therefore, the registration roller 27 can be swung based on the actual position of the side edge of the paper P after the transfer, and the position of the side edge of the paper P when the registration roller 27 passes can be adjusted. The deviation of the toner image position with respect to the paper P due to the scanning curve can be suppressed with high accuracy.

  Further, a position detection sensor 62 is disposed on the side of the surface of the paper P on which the toner image is transferred, and the control unit 11 is based on the position of the side edge of the paper P detected by the position detection sensor 62 and the position of the toner image. By determining the swing control information in this way, it is possible to suppress the deviation of the position of the toner image with respect to the paper P with higher accuracy based on the deviation amount of the paper P and the toner image.

  In addition, the control unit 11 determines the swing control information according to the conditions related to the paper transport such as the paper type and the environment, thereby performing the optimal swing control according to the conditions related to the paper transport. Is possible.

  Further, the control unit 11 determines the swing control information for each of a plurality of predetermined timings for swinging the registration roller 27 based on the detection result of the position detection sensor 62, thereby performing sub-scanning. The deviation of the toner image position with respect to the paper due to the bending can be suppressed with higher accuracy.

  Note that the description in the above embodiment shows a preferred example of the image forming apparatus according to the present invention, and the present invention is not limited to this.

  For example, in the above embodiment, the case where the position detection sensor 62 that detects the position of the side edge of the paper P is provided only downstream of the secondary transfer roller 9 and upstream of the fixing device 50 has been described as an example. A plurality of them may be provided, and the swing control information may be determined individually based on the respective detection results or based on the detection results of the plurality of position detection sensors.

  For example, as shown in FIG. 9, in addition to the position detection sensor 62 provided downstream of the secondary transfer roller 9 and upstream of the fixing device 50, a position detection sensor 64 (second detection unit) is provided upstream of the registration roller 27. It is good also as providing. Then, for example, when the position detection sensor 64 detects the position of the side edge of the paper P, the control unit 11 detects the position of the registration roller 27 based on the detection result (for example, based on the amount of deviation from the target position). After determining the swing control information and swinging the registration roller 27 and the position detection sensor 62 detects the side edge of the paper P, the swing control is performed by the method described in the first embodiment, for example. Information may be determined and the registration roller 27 may be swung. Further, when determining the swing control information in the first embodiment, the detection result of the position detection sensor 64 may be taken into account. In this way, in addition to the position detection sensor 62, the position detection sensor 64 is further provided upstream of the registration roller 27, and the position of the side edge of the paper P is adjusted by swinging the registration roller 27 based on the detection results. By doing so, the conveyance variation upstream of the registration roller 27 can be suppressed.

  Further, for example, as shown in FIG. 10, in addition to the position detection sensor 62 provided downstream of the secondary transfer roller 9 and upstream of the fixing device 50, downstream of the registration roller 27 and upstream of the secondary transfer roller 9. A position detection sensor 65 (third detection unit) may be provided. Then, for example, when the position detection sensor 65 detects the position of the side edge of the paper P, the control unit 11 detects the position of the registration roller 27 based on the detection result (for example, based on the amount of deviation from the target position). After determining the swing control information and swinging the registration roller 27 and the position detection sensor 62 detects the side edge of the paper P, the swing control is performed by the method described in the first embodiment, for example. Information may be determined and the registration roller 27 may be swung. In addition, when determining the swing control information in the first embodiment, the detection result of the position detection sensor 65 may be taken into account. In this way, in addition to the position detection sensor 62, the position detection sensor 65 is further provided downstream of the registration roller 27. Based on the detection results, the registration roller 27 is swung to adjust the position of the side edge of the paper P. By doing so, the conveyance variation of the registration roller 27 can be further suppressed. In addition, by providing the position detection sensor 65 downstream of the registration roller 27 as close as possible to the transfer portion, the paper position can be accurately aligned with the transfer position (image forming position).

  For example, as shown in FIG. 11, in addition to the position detection sensor 62 provided downstream of the secondary transfer roller 9 and upstream of the fixing device 50, a position detection sensor 66 (fourth detection) is further provided downstream of the fixing device 50. Part) may be provided. For example, when the position detection sensor 62 detects the position of the side edge of the paper P, the control unit 11 determines the swing control information of the registration roller 27 based on the detection result, and swings the registration roller 27. After the position detection sensor 66 detects the side edge of the sheet P, the registration roller 27 may be swung by determining the swing control information based on the detection result by the position detection sensor 66. . Further, when the swing control information is determined in the first embodiment, the detection result of the position detection sensor 66 may be taken into account. In this way, in addition to the position detection sensor 62, the position detection sensor 66 is further provided downstream of the fixing device 50, and the position of the side edge of the paper P is adjusted by swinging the registration roller 27 based on the detection results. By doing so, the conveyance variation of the fixing device 50 can be further suppressed.

  Further, in addition to the position detection sensor 62, a combination of two or more of the position detection sensor 64 shown in FIG. 9, the position detection sensor 65 shown in FIG. 10, and the position detection sensor 66 shown in FIG. The swing control information may be determined based on the detection result of the position detection sensor.

  Further, the control unit 11 calculates the inclination of the paper P based on the detection result of the position detection sensor 62 and any of the position detection sensors 64, 65, and 66, and at each swing timing based on the calculated inclination. The swing control information may be determined.

  In the above-described embodiment, the color image forming apparatus that primarily transfers the image formed on the photosensitive drum to the intermediate transfer roller and transfers the image from the intermediate transfer roller to the paper by the secondary transfer roller has been described as an example. However, the present invention is also applicable to a monochrome image forming apparatus that directly transfers an image from a photosensitive drum to a sheet by a transfer roller.

  In the above-described embodiment, the registration roller 27 is described as swinging in a direction orthogonal to the paper transport direction. However, the swing direction is not necessarily a direction orthogonal to the paper transport direction. You can change

  In the above embodiment, the case where the swing roller is the registration roller 27 has been described as an example. However, the present invention is not limited to this, and may be a separate body from the registration roller 27, for example.

  In the above description, an example in which a non-volatile memory, a hard disk, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of the image forming apparatus can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 11 Control part 12 Storage part 121 Swing control table 13 Communication part 14 Operation part SC Document reading apparatus 10 Image forming part 9 Secondary transfer roller 20 Paper conveyance part 27 Registration roller 50 Fixing apparatus 61 Registration sensor 62 Position detection Sensor 63 Environmental sensor 64 Position detection sensor 65 Position detection sensor 66 Position detection sensor 70 Suction fan

Claims (10)

A transfer section for transferring an image to paper;
A fixing unit for fixing the image transferred by the transfer unit to the paper;
In an image forming apparatus comprising:
A swing roller configured by a pair of rollers for transporting the paper being transported toward the transfer unit;
A detection unit that is disposed downstream of the transfer unit and upstream of the fixing unit and detects a position of a side edge of the sheet;
A control unit that performs swing control of the swing roller based on a detection result by the detection unit;
An image forming apparatus comprising:   The said control part determines the rocking | swiveling control information of the said rocking | swiveling roller based on the detection result by the said detection part, and performs rocking | fluctuation control of the said rocking | swiveling roller based on the determined rocking | fluctuation control information. The image forming apparatus according to 1. The detection unit is disposed on the side of the sheet on which the image is transferred, detects the position of the side edge of the sheet and the position of the image on the sheet,
The image forming apparatus according to claim 2, wherein the control unit determines the swing control information based on a position of a side edge portion of the sheet detected by the detection unit and a position of the image on the sheet.   The image forming apparatus according to claim 2, wherein the control unit further determines the swing control information according to a condition related to sheet conveyance.   The said control part determines the said rocking | swiveling control information for every some timing which rocks the said rocking | fluctuating roller based on the detection result by the said detection part, respectively. Image forming apparatus. A second detection unit that is disposed upstream of the swing roller and detects a position of a side edge of the paper;
The image forming apparatus according to claim 1, wherein the control unit further performs swing control of the swing roller based on a detection result of the second detection unit. A third detection unit that is disposed downstream of the swing roller and upstream of the transfer unit and detects a position of a side edge of the paper;
The image forming apparatus according to claim 1, wherein the control unit further performs swing control of the swing roller based on a detection result of the third detection unit. A fourth detection unit that is disposed downstream of the fixing unit and detects a position of a side edge of the paper;
The image forming apparatus according to claim 1, wherein the control unit further performs swing control of the swing roller based on a detection result of the fourth detection unit.   The image forming apparatus according to claim 1, wherein the swing roller swings in a direction orthogonal to a conveyance direction of the paper. A transfer section for transferring an image to paper;
A fixing unit for fixing the image transferred by the transfer unit to the paper;
A swing roller configured by a pair of rollers for transporting the paper being transported toward the transfer unit;
A control method of a swing roller in an image forming apparatus comprising:
A control method for performing swing control of the swing roller based on a detection result by a detection unit that is disposed downstream of the transfer unit and upstream of the fixing unit and detects a position of a side edge of the sheet.

Images