JP6926724B2 - Image forming device and control method - Google Patents

Description

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

In recent years, multifunctional image forming devices having functions such as printers, scanners, copiers, and fax machines have been widely used. In the image forming apparatus, the paper is conveyed from the paper feeding unit or the reversing path to the transfer unit at the time of image formation, but due to mechanical factors of the apparatus or the like, the direction in which the paper is orthogonal to the conveying direction (hereinafter, paper width). It may be biased to the direction). When the printing process is performed with the paper offset in this way, there arises a problem that the image formation position on the paper deviates from the original proper position.

Therefore, in order to accurately align the image and the paper in consideration of the paper bias, the resist roller holds the paper and swings it in the paper width direction to correct the paper bias. Dynamic correction is being performed.
For example, in Patent Document 1, a resist roller is arranged on the upstream side of the secondary transfer roller, and a line sensor is arranged on the downstream side of the resist roller and on the upstream side of the secondary transfer roller, and is detected by the line sensor. An image forming apparatus is disclosed that corrects the offset of the paper by swinging the paper in the width direction of the paper based on the position of the side edge portion of the paper.

Further, in Patent Document 2, a plurality of CIS are arranged downstream of the resist roller and upstream of the secondary transfer roller, and before the sheet rushes into the secondary transfer roller, the sheet has a CIS close to the resist roller side. The position of the side edge of the sheet is detected, and the resist roller is moved in the paper width direction based on the detection result. During transfer, the resist roller is moved based on the CIS detection result close to that of the secondary transfer roller to move the sheet. It is stated that the position of is corrected.

Japanese Unexamined Patent Publication No. 2013-91563 Japanese Unexamined Patent Publication No. 2014-133634

However, as in Patent Document 1 and Patent Document 2, even if the position of the paper side edge before passing through the secondary transfer roller is detected and the resist roller is shaken based on the detection result, the resist roller , The paper is transferred from the middle of the transport direction (secondary scanning direction) due to the misalignment of the secondary transfer roller and the fixing roller 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. Bending sub-scanning There are cases where the deviation between the paper and the image position due to bending cannot be suppressed accurately. In particular, since the transporting force of the fixing roller is large, there is a large tendency that sub-scanning bending occurs due to the influence of fixing, and the paper and the image are misaligned.

An object of the present invention is to suppress the deviation of the image position with respect to the paper due to the sub-scanning bend.

In order to solve the above problems, the invention according to claim 1 is
A transfer unit that transfers images to paper,
A fixing unit for fixing the image transferred by the transfer unit on the paper, and a fixing unit.
In an image forming apparatus including
An oscillating roller composed of a pair of rollers for transporting the conveyed paper toward the transfer unit, and
A detection unit that is arranged downstream of the fixing unit and detects the position of the side edge of the paper.
Based on the detection result by the detection unit, the swing control information of the swing roller is determined, and the control unit that controls the swing of the swing roller based on the determined swing control information.
Equipped with a,
The detection unit is arranged on the side of the surface on which the image of the paper is transferred, and detects the position of the side edge portion of the paper and the position of the image on the paper.
The control unit determines the swing control information based on the position of the side edge portion of the paper detected by the detection unit and the position of the image on the paper .

The invention according to claim 2 is the invention according to claim 1 .
The control unit further determines the swing control information according to the conditions related to paper transport.

The invention according to claim 3 is the invention according to claim 1 or 2 .
Based on the detection result by the detection unit, the control unit determines the swing control information for each of a plurality of timings for swinging the swing roller.

The invention according to claim 4 is the invention according to any one of claims 1 to 3.
A second detection unit, which is arranged upstream of the rocking roller and detects the position of the side edge portion of the paper, is further provided.
The control unit further controls the swing of the swing roller based on the detection result of the second detection unit.

The invention according to claim 5 is the invention according to any one of claims 1 to 4.
A third detection unit, which is arranged downstream of the rocking roller and upstream of the transfer unit and detects the position of the side edge portion of the paper, is further provided.
The control unit further controls the swing of the swing roller based on the detection result of the third detection unit.

The invention according to claim 6 is the invention according to any one of claims 1 to 5.
A fourth detection unit, which is arranged downstream of the transfer unit and upstream of the fixing unit and detects the position of the side edge portion of the paper, is further provided.
The control unit further controls the swing of the swing roller based on the detection result of the fourth detection unit.

The invention according to claim 7 is the invention according to any one of claims 1 to 6.
The swing roller swings in a direction orthogonal to the paper transport direction.

The invention according to claim 8 is
A transfer unit that transfers images to paper,
A fixing unit for fixing the image transferred by the transfer unit on the paper, and a fixing unit.
An oscillating roller composed of a pair of rollers for transporting the conveyed paper toward the transfer unit, and
It is a control method of a rocking roller in an image forming apparatus provided with.
The paper is arranged downstream of the fixing portion on the side of the surface on which the image of the paper is transferred, and is detected by a detection unit that detects the position of the side edge portion of the paper and the position of the image on the paper. The rocking control information of the rocking roller is determined based on the position of the side end portion of the paper and the position of the image on the paper, and the rocking control of the rocking roller is performed based on the determined rocking control information. conduct.

According to the present invention, it is possible to suppress the deviation of the image position with respect to the paper due to the sub-scanning bend.

It is a block diagram which shows typically the image forming apparatus which concerns on this embodiment. It is the figure which looked at the arrangement of the position detection sensor, and the rocking process of a paper by a resist roller seen from the upper surface. It is a figure which shows the arrangement of a position detection sensor and a suction fan. It is a block diagram which shows schematic structure of the control system of the image forming apparatus of FIG. FIG. 5 is a flowchart showing a swing control process A executed by the control unit of FIG. 4 in the first embodiment. It is a figure which shows an example of the sub-scanning bend. It is a figure which shows an example of a swing control table. FIG. 5 is a flowchart showing a swing control process B executed by the control unit of FIG. 4 in the second embodiment. It is a figure which shows the arrangement example of a position detection sensor. It is a figure which shows the arrangement example of a position detection sensor. It is a figure which shows the arrangement example 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>
[Structure of image forming apparatus 100]
First, the configuration of the image forming apparatus 100 in the first embodiment will be described.
FIG. 1 is a configuration diagram schematically showing 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 copier, and forms a full-color image by arranging a plurality of photoconductors in a vertical direction facing a single intermediate transfer belt. This is a so-called tandem type color image forming apparatus.

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

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

The image forming unit 10 includes four sets of image forming units 10Y, 10M, 10C, 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 an image of yellow (Y), an image forming unit 10M that forms an image of magenta (M), and an image that forms an image of cyan (C). It is composed of a forming unit 10C and an image forming unit 10K that forms a black (K) image.

The image forming unit 10Y includes a photoconductor drum 1Y, a charging unit 2Y arranged around the photoconductor drum 1Y, an optical writing unit 3Y, a developing device 4Y, and a drum cleaner 5Y. Similarly, the image forming units 10M, 10C, 10K include the photoconductor drums 1M, 1C, 1K and the charging units 2M, 2C, 2K arranged around them, the optical writing units 3M, 3C, 3K, the developing device 4M, and the like. It is composed of 4C, 4K and drum cleaners 5M, 5C, 5K.

The surface of the photoconductor drums 1Y to 1K is uniformly charged by the charging portions 2Y to 2K, and a latent image is formed on the photoconductor drums 1Y to 1K by scanning exposure by the optical writing units 3Y to 3K. Will be done. Further, the developing devices 4Y to 4K visualize the latent image on the photoconductor drums 1Y to 1K by developing with toner. As a result, a toner image of a predetermined color corresponding to any of yellow, magenta, cyan, and black is formed on the photoconductor drums 1Y to 1K. The toner image formed on the photoconductor drums 1Y to 1K is sequentially transferred to a predetermined position on the rotating intermediate transfer belt 6 by the primary transfer rollers 7Y, 7M, 7C, 7K.

The toner image composed of each color transferred on the intermediate transfer belt 6 is transferred by the secondary transfer roller 9 to the paper P transferred at a predetermined timing by the paper transport 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 placed in pressure contact with the intermediate transfer belt 6.

The paper transport unit 20 transports the paper P according to the transport path of the paper P. The paper P is housed in the paper feed tray 21, and the paper P housed 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 housed in a paper feed tray of a paper feed device (not shown) connected to the image forming device 100, and the paper P held by the paper feed device forms an image from the paper feed device. By being supplied to the device 100, it is sent out to the transport path.

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

In the present embodiment, intermediate transport rollers 23 to 25, loop rollers 26, and resist rollers 27 are provided as transport means from the upstream side to the downstream side of the paper P transport path. In addition to being composed of a pair of rollers, the transporting means can be widely adopted in a configuration composed of a pair of rotating members, such as a combination of belts and a combination of belts and rollers.

In such a transport path, the paper P fed from the paper feed tray 21 or the paper feed tray of the paper feed device is fed by a plurality of intermediate transport rollers 23 to 25 and loop rollers 26 provided from the upstream side to the downstream side. They are sequentially transported and proceed along the transport path. When the tip of the paper P approaches the resist roller 27, the paper P conveyed by the loop roller 26 or the like is abutted against the resist roller 27 in the stopped rotation 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 the action of this loop formation, the bending of the tip of the paper P is corrected (skew correction).

Next, when the resist 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 transfer rollers 23 to 25 and the loop roller 26 switch from the pressure contact state to the separated state. Be done. That is, after the loop roller 26 transitions to the separated state, the paper P is conveyed only by the resist roller 27. As a rocking roller, the resist roller 27 performs a rocking process described later while transporting the paper P to the transfer nip portion of the intermediate transfer belt 6 as the image carrier and the secondary transfer roller 9 as the transfer portion. And the paper P are conveyed.

As shown in FIG. 2, the resist roller 27 is configured to swing in the paper width direction CD (direction orthogonal to the paper transport direction (sub-scanning direction) FD). A drive mechanism 34 mainly composed of an electric motor (for example, a stepping motor) is connected to the resist roller 27, and by being driven by the drive mechanism 34, the CD in the paper width direction starts from a predetermined home position. You can move to.

The resist roller 27 moves the conveyed paper P along the paper width direction CD by moving along the paper width direction CD according to the passing period in which the paper P passes through itself (swing processing). As a result, the resist roller 27 adjusts the transport position of the paper P in the paper width direction CD so as to match the position of the transferred toner image.

A resist sensor 61 is arranged between the resist roller 27 and the loop roller 26 in the transport path. The resist sensor 61 detects the arrival of the tip of the paper P at the detection position of the resist sensor 61 (a position in front of the resist roller 27 by a predetermined distance). The detection result of the resist sensor 61 is used for detecting the rotation start timing of the resist roller 27 and the like.

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, and is, for example, a pair of fixing members (for example, a pair of rollers) and the fixing. It is composed of a heater that heats one or both of the members. In the process of transporting the paper P, the fixing device 50 fixes the toner image on the paper P through the action of the pressure of the pair of fixing members and the heat of the fixing members.

The paper P that has been fixed by the fixing device 50 is discharged by the paper ejection roller 28 to the paper ejection tray 29 attached to the outer side surface of the housing. Further, when the image is formed on the back surface of the paper P, the paper P that has finished forming the image on the front surface of the paper is conveyed to the reversing roller 31 below by the switching gate 30. The reversing roller 31 sandwiches the rear end of the conveyed paper P and then reverse-feeds the paper P to invert the paper P and feed it to the re-feeding and conveying path. The paper P fed to the re-feeding transfer path is conveyed by a plurality of re-feeding transfer means, and the paper P is returned to the transfer nip portion via the resist roller 27. The paper ejection roller 28, the switching gate 30, the reversing roller 31, and the conveying means for re-feeding also constitute the above-mentioned paper conveying section 20.

As shown in FIGS. 2 and 3, a position detection sensor 62 is provided on the image surface side of the paper P, which is downstream 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 a CD in the width direction of the paper, an optical system, a light source, and the like. The position detection sensor 62 is a detection unit that detects the position of the CD in the paper width direction at the side edge of the paper P after fixing. Further, in the present embodiment, since the position detection sensor 62 can read the paper P from the image surface side, it 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 resist roller 27 in the swing process.

Further, as shown in FIG. 3, a suction fan 70 is provided downstream of the fixing device 50 and below the transport path facing the position detection sensor 62. For example, since the paper P can be made to follow the lower guide (conveyor belt) by providing a ventilation hole or the like in the lower guide of the transport path and sucking with the suction fan 70, the toner on the paper P adheres to the position detection sensor 62. You can prevent it from happening. Further, the position detection sensor 62 can be arranged near the image surface, and the detection accuracy can be improved.

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 resist sensor 61, and a position detection sensor. 62, connected to the environment sensor 63 and the like. The control unit 11 is composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the control unit 11 reads out the system program and various processing programs stored in the storage unit 12 and expands them in the RAM, and centrally controls the operation of each unit of the image forming apparatus 100 according to the expanded program. For example, when the operation unit 14 inputs a job execution command, the control unit 11 executes the job and causes the paper P to form a toner image based on the image data input by the document reading device SC and the communication unit 13. Take control. Further, when the job execution command is input by the operation unit 14, the control unit 11 executes the swing control process A described later to control the swing of the resist roller 27 during job execution.

The storage unit 12 is composed of a non-volatile 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 required by each unit.

The communication unit 13 is provided with various interfaces such as NIC (Network Interface Card), MODEM (Modulator-DEModulator), and 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 the information displayed on the display can be used. Through such an operation unit 14, the user can set printing conditions, that is, the paper type, basis weight, size of paper P, paper feed tray to be used, image density, magnification, presence / absence of double-sided printing, and the like. In addition, the user can input a job execution command and an operation instruction in the adjustment mode through the operation unit 14. Further, 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 is configured to include, for example, a temperature sensor, a humidity sensor, and the like, detects the temperature and humidity inside 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 resist roller 27. The process shown in this flowchart is executed in collaboration with the program stored in the control unit 11 and the storage unit 12 in response to a job execution command from the user.

When the job is started, the control unit 11 waits for the tip of the paper P to be detected by the position detection sensor 62 (step S1).
When the tip 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 (for example, two points) by the position detection sensor 62. Acquire the result (step S2).

Next, the control unit 11 determines the swing control information of the resist roller 27 at each swing timing determined in advance based on the detection result by the position detection sensor 62 (step S3). Here, the swing timing is a timing at which the resist roller 27 is rocked. In the present embodiment, a plurality of swing timings (for example, at substantially equal intervals) are set in advance, for example, t1 second, t2 seconds, and so on from the timing when the position detection sensor 62 detects the tip of the paper P. It has been decided.

Here, since the fixing device 50 has a strong conveying force, as shown in FIG. 6, the paper P may be bent in the middle due to, for example, misalignment of the fixing device 50. Then, the position of the paper P shifts with respect to the transfer position of the toner image by the secondary transfer roller 9, and the toner image is at the optimum position (referred to as the optimum image position. For example, the center of the paper P in the width direction and the toner image). It will not be transferred to the position that coincides with the center in the width direction of. Therefore, in the present embodiment, the position detection sensor 62 provided downstream of the fixing device 50 detects the side end portion of the paper P, and the resist roller 27 is swung based on the detection result to cause the side of the paper P. The position of the end portion is adjusted to prevent the position of the paper P from being displaced with respect to the transfer position due to the influence of the fixing device 50. For example, in the case shown in FIG. 6, the resist roller 27 is swung in the direction of the arrow.

In step S3, for example, the control unit 11 acquires and acquires the detection result of the position of the end portion on the paper side (referred to as X1 and X2) by the position detection sensor 62 at two points in the sub-scanning direction on the front end side of the paper P. The inclination of the paper P is calculated based on the detected detection result. Then, based on the calculated inclination, the amount of deviation from the target position of the paper side edge at each swing timing is calculated, and based on the calculated deviation amount, the swing control information (swing amount, The rocking direction and rocking speed) are determined. 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 portion of the paper P passes through the position. Since the position of the resist 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 resist roller 27. It may be that.

The inclination of the paper P can be calculated by, for example, the following formula.
Inclination of paper P = (difference between X1 and X2 in the paper width direction) ÷ (conveyance distance between X1 and X2)
Further, the swing amount can be calculated by, for example, the following formula.
Amount of swing = amount of deviation from the target position on the paper side edge x α
Here, α is a coefficient. Since the transport state of the paper P differs depending on the conditions related to the paper transport, for example, the paper type, basis weight, environment (temperature, humidity, etc.), paper size (paper width, paper length), etc. of the paper P, the coefficient α is , It is preferable that the paper transport conditions and the swing timing (that is, the position in the swinging sub-scanning direction) differ. Further, it is preferable that the swing speed is increased as the swing amount increases.

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

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

Next, the control unit 11 determines whether or not the swing at the final swing timing is completed (step S6). For example, it is determined whether or not the swing at the final swing timing is completed based on the paper size of the paper P, the elapsed time since the position detection sensor 62 detects the tip of the paper P, and the transport speed. ..

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 arrives. Then, the process of swinging the resist roller 27 is repeated.

When it is determined that the swing at the final swing timing is completed (step S6; YES), the control unit 11 determines whether or not the transfer up to the final page is completed (step S7).
When it is determined that the transcription up to the final page has not been completed (step S7; NO), the control unit 11 returns to step S1.
When it is determined that the transfer up to the final page is 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 fixing device 50, and the detection result of the position detection sensor 62 on the front end side of the paper P (the position of the end portion on the paper side and / or the toner image). The swing of the resist roller 27 on the rear end side of the paper P is controlled based on the position). Therefore, it is possible to suppress the deviation of the toner image position with respect to the paper P due to the sub-scanning bending of the paper P caused by the influence of the fixing device 50.

<Second embodiment>
Next, a second embodiment of the present invention will be described.
In the second embodiment, an example of determining the swing control information of the resist roller 27 after the next paper will be described based on the detection result of the position detection sensor 62 provided downstream of the fixing device 50.

In the second embodiment, the storage unit 12 stores various programs executed by the control unit 11, parameters and data required by each unit, and a swing control table 121.
The swing control table 121 is a table in which swing control information for controlling the swing operation of the resist roller 27 is stored. On the swing control table 121, swing control information (here, swing amount, swing direction, swing speed) corresponding to a plurality of swing timings (timings 1 to n) in which the resist roller 27 is swing controlled is displayed. Are remembered respectively. In the present embodiment, the swing timing is set so as to swing from the front end to the rear end of the paper P at substantially equal intervals.
Here, the state when the paper P is transported is the conditions related to the paper transport, for example, the paper type, basis weight, environment (temperature, humidity, etc.), paper size (paper width, paper length), etc. of the paper P. In order to accurately write the toner image at the optimum image position of the paper P, it is preferable that the swing control table 121 stores the swing control information according to the conditions related to the paper transport. ..
FIG. 7 is a diagram showing an example of the swing control table 121. In FIG. 7, as an example, a swing control table 121 in which swing control information used at each swing timing (timing 1 to n) for each paper type is stored is shown.

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

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

When the job is started, the control unit 11 waits for the rocking timing of the resist roller 27 to arrive (step S11). Here, in the present embodiment, the swing timing is determined by the elapsed time after the resist sensor 61 detects the tip of the paper P, and the control unit 11 detects the tip of the paper P by the resist sensor 61. It is determined whether or not the swing timing has arrived based on the elapsed time since then.

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

The control unit 11 repeatedly executes steps S11 to S13 until the rocking of the resist roller 27 at the final rocking timing is completed, and swings the resist roller 27 at each rocking timing. When the paper P reaches the position detection sensor 62 during this period, the position detection sensor 62 detects, for example, the position of the paper side end portion and the position of the toner image for each line and outputs the position to the control unit 11.

When it is determined that the rocking of the resist roller 27 at the final rocking timing is completed (step S13; YES), the control unit 11 acquires the detection result by the position detection sensor 62 at the position corresponding to each rocking timing. (Step S14). For example, the control unit 11 identifies a region of the paper P and a region of the toner image from the detection result (scanned image) by the position detection sensor 62, and the paper P at a position corresponding to each swing timing in the sub-scanning direction of the paper P. Acquires the position of the side edge of the toner image and the toner image.

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

Then, the control unit 11 corrects the swing control information and updates the swing control table 121 based on the correction values calculated for each swing timing (step S16). That is, the swing control information corrected by the calculated correction value overwrites the swing control information according to the swing timing of the swing control table 121 and the conditions related to the paper transport, and the swing control table 121 is stored in the storage unit 12. To memorize.

Here, since the fixing device 50 has a strong conveying force, the deviation of the image position of the toner image with respect to the paper P tends to be larger toward the rear end where the toner image is transferred after the tip of the paper P reaches the fixing device 50. be. In the swing control process B, each position in the sub-scanning direction corresponding to each swing timing is based on the detection result of the position of the paper side edge and the toner image by the position detection sensor 62 after passing through the fixing device 50. The amount of deviation in the positional relationship between the paper side edge and the toner image (the amount of deviation from the optimum positional relationship) is calculated, and based on the calculated deviation amount, the swing control information at each swing timing is corrected and rocked. Since the motion control table 121 is updated, the swing control information can be individually corrected for each swing timing based on the image deviation of each position in the sub-scanning direction. It is possible to suppress the deviation between the paper and the image position with high accuracy.

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

The swing control process B is a process of correcting swing control information used for subsequent swing control (after the next paper) based on the swing operation of the resist roller 27 during job execution. Reference numeral 100 denotes an adjustment mode, in which the swing control information of the swing control table 121 can be set or corrected in advance before the job is executed. For example, when the operation unit 14 instructs the operation in the adjustment mode, the control unit 11 conveys a predetermined number of sheets from the paper feed tray 21 or the paper feed tray of the paper feed device, and stores the predetermined number of sheets in the storage unit 12 in advance. An image is formed by the image forming units 10Y to 10K based on the image data, and the image is transferred to paper by the secondary transfer roller 9. Further, the control unit 11 causes the resist roller 27 to swing and detect the side edge of the paper on which the image is transferred and the position detection sensor 62 of the toner image by the same control as the swing control process B. The swing control information is set or corrected in the swing control table 121 based on the detection result. 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 deviation between the paper and the image position with respect to the first sheet of paper can be set or corrected in advance. It is possible to provide a print with a good finish.

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

Further, in the swing control process B, when the swing control information used for swing control of the resist roller 27 on the next paper is corrected based on the detection result by the position detection sensor 62 on the front paper during job execution. However, the swing control information used for swing control of the resist roller 27 on the rear end side of the own paper may be corrected. For example, in the case of long paper or other paper having a long paper transport direction, 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 determines the position of the toner image based on the detection result. The correction value of the swing control information may be calculated to correct the swing control information, and the resist roller 27 on the rear end side of the own paper may be controlled based on the corrected swing control information.

Further, in the swing control process B, the swing control information of the swing control table 121 is directly rewritten by the correction value calculated in step S15, but the storage unit 12 is related to the swing timing and the paper transfer. A correction value table for storing correction values may be provided according to the conditions. 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 paper transport, and then swing control when the resist roller 27 is swing controlled. The rocking control of the resist roller 27 may be performed based on the rocking control information based on the correction values of the table 121 and the correction value table.

As described above, according to the image forming apparatus 100, the image forming apparatus 100 includes a position detecting sensor 62 which is arranged downstream of the fixing apparatus 50 and detects the position of the side end portion of the paper P, and the control unit 11 includes the position detecting sensor 62. The rocking control of the resist roller 27 is performed based on the detection result of the above. For example, the rocking control information of the resist roller 27 is determined based on the detection result of the position detection sensor 62, and the rocking control of the resist roller 27 is performed based on the determined rocking control information.
Therefore, the resist roller 27 can be swung based on the position of the side end portion of the paper P after fixing, and the position of the side end portion of the paper P when the resist roller 27 passes can be adjusted. The deviation of the toner image position with respect to the paper P due to the influence of the device 50 can be suppressed with high accuracy.

Further, the position detection sensor 62 is arranged on the side of the surface on which the toner image of the paper P is transferred, and the control unit 11 is based on the position of the side end portion of the paper P detected by the position detection sensor 62 and the position of the toner image. By determining the swing control information, 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 amount of deviation between the paper P and the toner image.

Further, 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 optimum 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 resist roller 27 based on the detection result of the position detection sensor 62, thereby performing the sub-scanning. It is possible to suppress the deviation of the toner image position with respect to the paper due to bending with higher accuracy.

The description in the above embodiment shows a suitable example of the image forming apparatus according to the present invention, and is not limited thereto.

For example, in the above embodiment, the case where the position detection sensor 62 for detecting the position of the side end portion of the paper P is provided only downstream of the fixing device 50 has been described as an example, but a plurality of position detection sensors 62 are provided on the transport path and each of them is detected. The swing control information may be determined individually based on the result or based on the detection result 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 fixing device 50, the position detection sensor 64 (second detection unit) may be provided upstream of the resist roller 27. Then, for example, when the position detection sensor 64 detects the position of the side end portion of the paper P, the control unit 11 of the resist roller 27 (for example, based on the amount of deviation from the target position) based on the detection result. After the rocking control information is determined to swing the resist roller 27 and the side edge of the paper P is detected by the position detection sensor 62, the rocking control is performed by, for example, the method described in the first embodiment. The information may be determined and the resist roller 27 may be shaken. Further, when determining the swing control information in the first embodiment, the detection result of the position detection sensor 64 may be taken into consideration. In this way, in addition to the position detection sensor 62, a position detection sensor 64 is further provided upstream of the resist roller 27, and the resist roller 27 is swung based on these detection results to adjust the position of the side end portion of the paper P. By doing so, it is possible to further suppress the transfer variation upstream of the resist roller 27.

Further, for example, as shown in FIG. 10, in addition to the position detection sensor 62, the position detection sensor 65 (third detection unit) may be provided downstream of the resist roller 27 and upstream of the secondary transfer roller 9. good. Then, for example, when the position detection sensor 65 detects the position of the side end portion of the paper P, the control unit 11 of the resist roller 27 (for example, based on the amount of deviation from the target position) based on the detection result. After the rocking control information is determined to swing the resist roller 27 and the side edge of the paper P is detected by the position detection sensor 62, the rocking control is performed by, for example, the method described in the first embodiment. The information may be determined and the resist roller 27 may be shaken. Further, when determining the swing control information in the first embodiment, the detection result of the position detection sensor 65 may be taken into consideration. In this way, in addition to the position detection sensor 62, a position detection sensor 65 is further provided downstream of the resist roller 27, and the resist roller 27 is swung based on these detection results to adjust the position of the side end portion of the paper P. By doing so, it is possible to further suppress the transfer variation of the resist roller 27. In addition, by providing the position detection sensor 65 downstream of the resist roller 27 as close as possible to the transfer portion, it is possible to accurately align the paper position with respect to the transfer position (image formation position).

Further, for example, as shown in FIG. 11, in addition to the position detection sensor 62, the position detection sensor 66 (fourth detection unit) may be provided downstream of the secondary transfer roller 9 and upstream of the fixing device 50. good. Then, for example, when the position detection sensor 66 detects the position of the side end portion of the paper P, the control unit 11 of the resist roller 27 (for example, based on the amount of deviation from the target position) based on the detection result. The rocking control information is determined to swing the resist roller 27, and after the position detection sensor 62 detects the side edge of the paper P, the position detection sensor swing control information is determined to swing the resist roller 27. It may be moved. Further, when determining the swing control information in the first embodiment, the detection result of the position detection sensor 66 may be taken into consideration. As described above, by providing the position detection sensor 66 downstream of the secondary transfer roller 9 in addition to the position detection sensor 62, it is possible to further suppress the transfer variation of the secondary transfer roller 9. In addition, by providing the position detection sensor 66 downstream of the transfer unit as close as possible to the transfer unit, it is possible to accurately align the paper position with respect to the transfer position (image drawing position).

Further, in addition to the position detection sensor 62, 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 sensor 66 shown in FIG. 11 are provided in combination, and the control unit 11 has a plurality of control units 11. 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, 66, and at each swing timing based on the calculated inclination. The swing control information may be determined.

Further, in the above embodiment, a color image forming apparatus in which the image formed on the photoconductor drum is primarily transferred to the intermediate transfer roller and the image is transferred from the intermediate transfer roller to the paper by the secondary transfer roller will be described as an example. However, the present invention is also applicable to a monochrome image forming apparatus that transfers an image directly from a photoconductor drum to paper by a transfer roller.

Further, in the above embodiment, the resist roller 27 has been described as swinging in a direction orthogonal to the paper transport direction, but the swing direction does not necessarily have to be a direction orthogonal to the paper transport direction, and the paper feed direction. I wish I could change.

Further, in the above embodiment, the case where the rocking roller is the resist roller 27 has been described as an example, but the present invention is not limited to this, and for example, the rocking roller may be a separate body from the resist roller 27.

Further, 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 has been 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 data of the program according to the present invention via a communication line.

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

100 Image forming device 11 Control unit 12 Storage unit 121 Swing control table 13 Communication unit 14 Operation unit SC Document reading device 10 Image forming unit 9 Secondary transfer roller 20 Paper transport unit 27 Resist roller 50 Fixing device 60 Image reading unit 61 Resist Sensor 62 Position detection sensor 63 Environment sensor 64 Position detection sensor 65 Position detection sensor 66 Position detection sensor 70 Suction fan

Claims (8)

A transfer unit that transfers images to paper,
A fixing unit for fixing the image transferred by the transfer unit on the paper, and a fixing unit.
In an image forming apparatus including
An oscillating roller composed of a pair of rollers for transporting the conveyed paper toward the transfer unit, and
A detection unit that is arranged downstream of the fixing unit and detects the position of the side edge of the paper.
Based on the detection result by the detection unit, the swing control information of the swing roller is determined, and the control unit that controls the swing of the swing roller based on the determined swing control information.
Equipped with a,
The detection unit is arranged on the side of the surface on which the image of the paper is transferred, and detects the position of the side edge portion of the paper and the position of the image on the paper.
The control unit is an image forming apparatus that determines the swing control information based on the position of the side edge portion of the paper detected by the detection unit and the position of the image on the paper. The image forming apparatus according to claim 1 , wherein the control unit further determines the swing control information according to conditions related to paper transport. The image forming apparatus according to claim 1 or 2 , wherein the control unit determines the rocking control information for each of a plurality of timings at which the rocking roller is swung based on the detection result of the detection unit. A second detection unit, which is arranged upstream of the rocking roller and detects the position of the side edge portion of the paper, is further provided.
The image forming apparatus according to any one of claims 1 to 3 , wherein the control unit further controls the swing of the swing roller based on the detection result of the second detection unit. A third detection unit, which is arranged downstream of the rocking roller and upstream of the transfer unit and detects the position of the side edge portion of the paper, is further provided.
The image forming apparatus according to any one of claims 1 to 4 , wherein the control unit further controls the swing of the swing roller based on the detection result of the third detection unit. A fourth detection unit, which is arranged downstream of the transfer unit and upstream of the fixing unit and detects the position of the side edge portion of the paper, is further provided.
The image forming apparatus according to any one of claims 1 to 5 , wherein the control unit further controls the swing of the swing roller based on the detection result of the fourth detection unit. The image forming apparatus according to any one of claims 1 to 6 , wherein the swing roller swings in a direction orthogonal to the paper transport direction. A transfer unit that transfers images to paper,
A fixing unit for fixing the image transferred by the transfer unit on the paper, and a fixing unit.
An oscillating roller composed of a pair of rollers for transporting the conveyed paper toward the transfer unit, and
It is a control method of a rocking roller in an image forming apparatus provided with.
The paper is arranged downstream of the fixing portion on the side of the surface on which the image of the paper is transferred, and is detected by a detection unit that detects the position of the side edge portion of the paper and the position of the image on the paper. The rocking control information of the rocking roller is determined based on the position of the side end portion of the paper and the position of the image on the paper, and the rocking control of the rocking roller is performed based on the determined rocking control information. Control method to be performed.

Images