JP7027701B2 - 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 inversion path to the transfer unit at the time of image formation, but due to mechanical factors of the apparatus, the paper is orthogonal to the conveying direction (hereinafter, paper width). It may be biased to the direction). When the printing process is performed in a state where the paper is offset in this way, there arises a problem that the position where the image is formed 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 image forming position, 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 the line sensor is detected. An image forming apparatus for correcting a paper offset by swinging the paper in the paper width direction based on the amount of the paper offset is disclosed.

Japanese Unexamined Patent Publication No. 2013-91563

By the way, in the conventional technique including Patent Document 1, the resist roller swings before the tip of the paper reaches the secondary transfer roller, and the positions of the side edges of the paper are aligned. However, simply shaking the paper before it reaches the secondary transfer roller causes misalignment of the resist roller, secondary transfer roller, and fixing roller, and the front side of each roller when the image forming apparatus is viewed from the front. Due to the difference in roller diameter between the back side and the back side, sub-scanning bending occurs in which the paper bends from the middle of the transport direction (sub-scanning direction). In addition, skew correction that abuts the leading edge of the paper against the resist roller to correct the skewing of the paper corrects the skewing of the leading edge of the paper, but does not correct the trailing edge, leaving distortion between the leading edge and the trailing edge. Therefore, the sub-scanning bend occurs (see FIG. 7). In particular, long paper is susceptible to this effect, so that sub-scanning bending occurs remarkably. If printing is performed in a state where the sub-scanning bend occurs, the image formation position shifts from the middle with respect to the paper.

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
In an image forming apparatus that conveys paper to a transfer unit and transfers an image to the paper.
An oscillating roller composed of a pair of rollers that transport the conveyed paper toward the transfer unit, and
A detection unit arranged between the rocking roller and the transfer unit to detect the position of the side edge portion of the paper.
The rocking roller is controlled to swing before the paper rushes into the transfer portion and after the paper rushes into the transfer portion, and at least after the paper rushes into the transfer portion, the detection unit performs the swing control. A control unit that swings the swing roller based on the detected detection result and predetermined swing control information, and a control unit that swings the swing roller.
An image reading unit that reads the paper on which an image is transferred by passing through the transfer unit and acquires a scanned image including a region of the paper and an area of the image.
A correction unit that acquires the distance between the edge of the paper and the image from the scanned image acquired by the image reading unit and corrects the swing control information based on the acquired distance .
To prepare for.

The invention according to claim 2 is the invention according to claim 1.
The correction unit determines a correction value of the swing control information based on the distance acquired from the image read by the image reading unit, and stores the determined correction value in the storage unit.

The invention according to claim 3 is the invention according to claim 2.
The storage unit stores a table in which correction values of the swing control information are stored according to conditions related to paper transport.

The invention according to claim 4 is the invention according to claim 1.
It is equipped with a storage unit that stores a table that stores the swing control information according to the conditions related to paper transport.
The correction unit determines a correction value of the swing control information based on the distance acquired from the image read by the image reading unit, and uses the determined correction value to obtain the swing control information stored in the table. to correct.

The invention according to claim 5 is the invention according to claim 3 or 4.
It is provided with an adjustment mode in which a sheet of paper is passed, an image is transferred to the sheet of paper, the image is read by the image reading unit, and the table is set or corrected based on the distance acquired from the scanned image .

The invention according to claim 6 is the invention according to any one of claims 1 to 5.
The correction unit corrects the swing control information in real time based on the distance acquired from the scanned image each time the image reading unit reads the image.

The invention according to claim 7 is the invention according to any one of claims 1 to 5.
The correction unit corrects the swing control information based on the calculated value of the deviation amount based on the distance acquired from the scanned image acquired by the image reading unit in a predetermined period.

The invention according to claim 8 is the invention according to any one of claims 1 to 7.
The control unit performs the swing control based on a plurality of swing control information according to the timing of swinging the swing roller.
The correction unit corrects a plurality of swing control information according to the timing of swinging the swing roller based on the distance acquired from the image read by the image reading 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
An oscillating roller composed of a pair of rollers that transport the conveyed paper toward the transfer unit.
A detection unit arranged between the rocking roller and the transfer unit to detect the position of the side edge portion of the paper.
It is a control method of a rocking roller in an image forming apparatus provided with.
The paper is at least after the paper has rushed into the transfer portion by the control unit that controls the swing of the swing roller before the paper has rushed into the transfer portion and after the paper has rushed into the transfer portion. A process of swinging the swing roller based on the detection result detected by the detection unit and predetermined swing control information, and
A step of reading the paper on which an image is transferred by passing through the transfer unit by an image reading unit to acquire a scanned image including a region of the paper and a region of the image .
A step of acquiring the distance between the edge of the paper and the image from the scanned image acquired by the image reading unit and correcting the swing control information based on the acquired distance .
including.

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 explanatory drawing which shows the rocking process of a paper by a resist roller. It is a block diagram schematically showing the structure of the control system of the image forming apparatus of FIG. It is a figure which shows the data storage example of a swing control table. It is a flowchart which shows the swing control process A executed by the control part of FIG. 3 in 1st Embodiment. 2 is a flowchart showing a swing control process B executed by the control unit of FIG. 3 in the second embodiment. It is a figure which shows an example of a sub-scanning bend.

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 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 type 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, an image reading unit 60, 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 an image of black (K).

The image forming unit 10Y is composed of a photoconductor drum 1Y and 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 transport 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 as 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 an image carrier and the secondary transfer roller 9 as a transfer portion. And the paper P are conveyed.

FIG. 2 is an explanatory diagram showing a swing process of the paper P by the resist roller 27. The resist roller 27 is configured to be swingable 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 is connected to the resist roller 27, and by being driven by the drive mechanism 34, the resist roller 27 can move to the CD in the paper width direction starting from a predetermined home position. ..

The resist roller 27 can move 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). process). 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. Here, the position where the side end portion of the paper P should pass in the CD in the paper width direction is referred to as a target position Tp. This target position Tp has an optimum positional relationship between the paper P and the toner image (for example, the center in the width direction of the paper P) if the side edge portion of the paper P passes through the position in the paper width direction CD. The position is expected to coincide with the center of the toner image in the width direction), and the resist roller 27 adjusts the transport position of the CD in the width direction of the paper P so that the side edge portion of the paper P becomes the target position Tp. do. The position of the toner image in which the positional relationship between the paper P and the toner image is optimum is called the optimum image position.

A resist sensor SE1 and a position detection sensor SE2 are provided in the transport path, and the operation of the resist roller 27 is controlled by the control unit 11 based on the detection results of these sensors.

The resist sensor SE1 is arranged between the resist roller 27 and the loop roller 26 in the transport path, and the tip of the paper P reaches the detection position of the resist sensor SE1 (a position in front of the resist roller 27 by a predetermined distance). Is detected. The detection result of the resist sensor SE1 is used for detecting the rotation start timing of the resist roller 27 and the like.

The position detection sensor SE2 is a detection unit that detects the position of the CD in the paper width direction at the side edge of the paper P. As the position detection sensor SE2, for example, a linear image sensor (for example, a CCD line sensor or the like) in which a plurality of light receiving elements are linearly arranged along a CD in the width direction of the paper can be used. The detection result of this position detection sensor SE2 is used for determining the amount of movement of the resist roller 27 in the rocking process and the like.

As shown in FIG. 1 again, 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 fixing members (for example). It is composed of a pair of rollers) and a heater that heats one or both of the fixing 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 member.

The paper P that has been fixed by the fixing device 50 is read by the image reading unit (ICCU) 60 and then discharged by the paper ejection roller 28 to the paper ejection 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 that has finished image formation on the paper surface is read by the image reading unit 60 and then conveyed to the reversing roller 31 below by the switching gate 30. Will be done. 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.

The image reading unit 60 is configured to include, for example, a linear image sensor (for example, a CCD line sensor or the like), an optical system, a light source, or the like, reads the paper P on which the toner image is transferred, and controls the obtained scanned image. Output to 11. In the present embodiment, the image reading unit 60 can measure the color of the toner image on the paper P, but is not particularly limited as long as it can recognize at least the area of the paper P and the area of the toner image. Further, in the present embodiment, it is assumed that the image reading unit 60 is located downstream of the fixing device 50 and on the front side where the transport path is switched by the switching gate 30, but is downstream of the secondary transfer roller 9. The arrangement position is not particularly limited as long as both sides of the paper P (may be one side at a time) can be read. Of course, it may be arranged downstream of the image forming apparatus 100 as an optional device.

FIG. 3 is a block diagram schematically showing the configuration of the control system of the image forming apparatus 100 according to the present embodiment.
As shown in FIG. 3, 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, an image reading unit 60, and a resist sensor. It is connected to SE1, position detection sensor SE2, and environment sensor SE3. 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 job execution command is input by the operation unit 14, 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, and corrects the swing control and swing control information of the resist roller 27 during job execution. conduct.

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.

For example, the storage unit 12 stores the swing control table 121 and the correction value table 122.

The swing control table 121 is a table in which swing control information for controlling the swing operation of the resist roller 27 (here, as an example, the target position Tp of the paper P and the swing speed) is stored. The swing control table 121 stores swing control information according to the swing timing (timing 1 to n) in which the resist roller 27 is swing controlled. In the present embodiment, for example, the timing when the position detection sensor SE2 detects the tip of the paper is 0 seconds, the section from 0 seconds to T1 seconds is timing 1, the section from T1 to T2 seconds is timing 2, ... Tn. It is assumed that the swing control information corresponding to a plurality of timings 1 to n is stored with the section from -1 to Tn seconds (Tn is, for example, the timing when the paper P passes through the resist roller 27) as the timing n. , The swing control information may be stored in detail for each detection timing of the position detection sensor SE2. The timings 1 to n include the timing before the paper P rushes into the secondary transfer roller 9 and the timing after the paper P rushes into the secondary transfer roller 9. That is, on the swing control table 121, the swing control information used for swing control of the resist roller 27 before the paper P rushes into the secondary transfer roller 9 and after the paper P rushes into the secondary transfer roller 9. The swing control information used for swing control of the resist roller 27 is stored.

Here, the swing control information for forming the toner image at the optimum image position without generating noise or the like includes the paper type (basis weight, size, paper quality, etc.) and environment (for example, temperature and humidity) of the paper P. It depends on the conditions related to paper transport such as the paper surface (front / back surface) on which the image is formed and the paper feed tray. That is, in order to accurately write the toner image at the optimum image position of the paper P, the rocking control table 121 is rocked according to the conditions related to the paper transport such as the paper type, environment, printing surface, and paper feed tray. It is preferable that the information is stored.
FIG. 4 is a diagram showing an example of the swing control table 121. FIG. 4 shows, as an example, a swing control table 121 in which swing control information used at each swing timing (timing 1 to n) is stored for each paper type.

The correction value table 122 is a table for storing correction values for correcting the swing control information of the swing control table 121.
Here, even if the side edge portion of the paper P is aligned with the target position Tp, the toner image may not always be formed at the optimum image position due to the above-mentioned sub-scanning bend or the like. Further, the amount of deviation varies depending on the paper type of the paper P, the environment, the paper surface, the paper transport conditions such as the paper feed tray of the paper P, and the like. Therefore, the correction value table 122 stores the correction value for the swing control information of each swing timing of the swing control table 121 according to the conditions related to the paper transport such as the paper type, environment, printing surface, and paper feed tray. ..

In the present embodiment, the swing control information (for example, target position Tp, etc.) used for swing control of the resist roller 27 is a correction value table 122 of the swing control information stored in the swing control table 121. It is the information corrected by the correction value of.

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 the operation unit 14, the user sets printing conditions, that is, the type of paper P (for example, basis weight, size, paper quality, etc.), paper feed tray to be used, image density, magnification, presence / absence of double-sided printing, and the like. be able to. Further, the user can input a job execution command and an operation instruction in the adjustment mode through the operation unit 14. Further, by controlling the operation unit 14, the control unit 11 can display various messages to the user via the operation unit 14.

The environment sensor SE3 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 and the position of the side edge of the paper P is detected by the position detection sensor SE2 (step S1), the control unit 11 determines the detection result by the position detection sensor SE2, the swing control table 121, and the correction value. Based on the swing timing and the target position Tp according to the conditions related to the paper transport specified by the table 122, it is determined whether or not the side end portion of the paper P deviates from the target position Tp (step S2). ..

When it is determined that the side end portion of the paper P does not deviate from the target position Tp (step S2; NO), the control unit 11 returns to step S1.

When it is determined that the end portion of the paper P deviates from the target position Tp (step S2; YES), the control unit 11 swings the resist roller 27 by the drive mechanism 34 (step S3). That is, the swing amount and swing direction of the resist roller 27 are determined based on the deviation amount between the position of the side end portion of the paper P and the target position Tp, and the swing control is performed by the swing amount determined in the determined swing direction. The resist roller 27 is rocked and stopped by the drive mechanism 34 at a rocking speed specified by the table 121 and the correction value table 122 according to the rocking timing and the conditions related to the paper transport.

Next, the control unit 11 determines whether or not the rear end of the paper P has passed through the resist roller 27 (step S4). For example, the control unit 11 determines that the rear end of the paper P has passed through the resist roller 27 when a predetermined time corresponding to the transport speed has elapsed after the resist sensor SE1 detects the rear end of the paper P.

When it is determined that the rear end of the paper P has not passed through the resist roller 27 (step S4; NO), the control unit 11 returns to step S1 and repeatedly executes the processes of steps S1 to S4.

Here, in the present embodiment, not only before the paper P rushes into the secondary transfer roller 9 as in the conventional case, but also after the paper P rushes into the secondary transfer roller 9, steps S1 to step S1 to step continuously. The process of S4 is repeatedly executed. Therefore, since the position of the paper side end portion can be corrected not only on the front end side of the paper P but also on the rear end side, the sub-scanning bend that occurs remarkably on paper long in the paper transport direction such as long paper can be prevented. It can be corrected.

When it is determined that the rear end of the paper P has passed through the resist roller 27 (step S4; YES), the control unit 11 uses the image reading unit 60 to read the paper P on which the toner image is formed by passing through the secondary transfer roller 9. It is read (step S5), and the correction value of the swing control information is calculated based on the read image acquired by the image reading unit 60 (step S6).

In step S6, for example, the control unit 11 identifies a region of the paper P and a region of the toner image from the scanned image, and a position corresponding to each swing timing in the sub-scanning direction of the paper P (reference position of each swing timing). ), The distance between the side edge of the paper P and the toner image is acquired. 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 target position Tp at each swing timing is calculated.

Further, the control unit 11 detects noise in the toner image region based on the scanned image acquired by the image reading unit 60. For example, noise (image defect) is detected by collating the value of the toner image area in the scanned image with the value of the original image. Here, after the paper P is rushed into the secondary transfer roller 9, the paper P swings in a state of being sandwiched by the secondary transfer roller 9. Therefore, if the swing speed is too fast, noise due to transfer misalignment or the like is generated. Therefore, the control unit 11 detects noise in the toner image region and calculates a correction value for lowering the swing speed at the swing timing corresponding to the position where the noise is generated.

Then, the control unit 11 updates the correction value table 122 according to the correction value calculated for each swing timing (step S7). That is, the calculated correction value overwrites the correction value according to the swing timing of the correction value table 122 and the conditions related to the paper transport, and the overwritten correction value table 122 is stored in the storage unit 12.

Here, even if the side end portion of the paper P is aligned with the target position Tp at the position of the position detection sensor SE2, the sub-scanning bend occurs as described above, and the image of the toner image with respect to the paper P as it goes to the rear end. The misalignment tends to be large. In particular, the deviation is remarkable for paper that is long in the paper transport direction, such as long paper. In the present embodiment, the correction values of the swing control information at the plurality of positions corresponding to the plurality of swing timings in the sub-scanning direction of the paper P are calculated and stored in the correction value table 122, so that each of the sub-scanning directions The swing control information can be individually corrected based on the image misalignment and noise at the position of, and the misalignment between the paper and the image position due to the sub-scanning bend can be suppressed with high accuracy. In addition, since the edges on the same side are always aligned, it is possible to suppress the influence of variations in the outer shape of the paper.

Next, the control unit 11 determines whether or not the transcription up to the final page is completed (step S8).
If it is determined that the transcription up to the final page has not been completed (step S8; NO), the control unit 11 returns to step S1.
When it is determined that the transfer up to the final page is completed (step S8; YES), the control unit 11 ends the swing control process A.

The swing control process A is a process for correcting swing control information used for subsequent swing control based on the swing operation of the resist roller 27 during job execution. The image forming apparatus 100 has an adjustment mode. Therefore, in the adjustment mode, the correction value can be set or corrected in advance in the correction value table 122 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 toner image is transferred to the paper by the secondary transfer roller 9. Further, the control unit 11 causes the resist roller 27 to swing and the paper on which the toner image is transferred to be read by the image reading unit 60 under the same control as the shaking control process A, and the reading result by the image reading unit 60. The correction value of the swing control information is calculated based on the above, and the calculated correction value is set or corrected in the correction value table 122. As described above, since the image forming apparatus 100 has the adjustment mode, the correction value can be set or corrected in advance in the correction value table 122 before the job is executed, and the image position shifts from the first sheet to the paper. It is possible to provide a print with a good finish.

<Second embodiment>
Next, the second embodiment will be described.
In the first embodiment, an example in which the corrected value of the calculated swing control information is stored in the correction value table 122 has been described, but in the second embodiment, the swing corrected by the calculated correction value has been described. An example of storing the dynamic control information in the swing control table 121 will be described.

The storage unit 12 of the second embodiment stores a program for executing the swing control process B described later. Further, the storage unit 12 stores the swing control table 121 described in the first embodiment.
Since the other configurations in the second embodiment are the same as those described in the first embodiment, the description will be incorporated, and the operation in the second embodiment will be described below.

FIG. 6 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 and the position of the side end portion of the paper P is detected by the position detection sensor SE2 (step S21), the control unit 11 is specified by the detection result by the position detection sensor SE2 and the swing control table 121. It is determined whether or not the side end portion of the paper P deviates from the target position Tp based on the swing timing and the target position Tp according to the conditions related to the paper transport (step S22).

When it is determined that the side end portion of the paper P does not deviate from the target position Tp (step S22; NO), the control unit 11 returns to step S21.

When it is determined that the side end portion of the paper P deviates from the target position Tp (step S22; YES), the control unit 11 swings the resist roller 27 by the drive mechanism 34 (step S23). That is, the swing amount and swing direction of the resist roller 27 are determined based on the deviation amount between the position of the side end portion of the paper P and the target position Tp, and the swing control is performed by the swing amount determined in the determined swing direction. The resist roller 27 is shaken and stopped by the drive mechanism 34 at a swinging speed according to the swinging timing and the conditions related to the paper transport specified by the table 121.

Next, the control unit 11 determines whether or not the rear end of the paper P has passed through the resist roller 27 (step S24). For example, the control unit 11 detects that the rear end of the paper P has passed through the resist roller 27 when a predetermined time corresponding to the transport speed has elapsed after the resist sensor SE1 detects the rear end of the paper P. ..

When it is determined that the rear end of the paper P has not passed through the resist roller 27 (step S24; NO), the control unit 11 returns to step S21 and repeatedly executes the processes of steps S21 to S24.

Here, in the present embodiment, not only before the paper P rushes into the secondary transfer roller 9 as in the conventional case, but also after the paper P rushes into the secondary transfer roller 9, steps S21 to step are continued. The process of S24 is repeatedly executed. Therefore, since the position of the paper side end portion can be corrected not only on the front end side of the paper P but also on the rear end side, the sub-scanning bend that occurs remarkably on paper long in the paper transport direction such as long paper can be prevented. It can be corrected.

When it is determined that the rear end of the paper P has passed through the resist roller 27 (step S24; YES), the control unit 11 uses the image reading unit 60 to read the paper P on which the toner image is formed by passing through the secondary transfer roller 9. It is read (step S25), and the correction value of the swing control information is calculated based on the read image acquired by the image reading unit 60 (step S26).

In step S26, for example, the control unit 11 identifies a region of the paper P and a region of the toner image from the scanned image, and a position corresponding to each swing timing in the sub-scanning direction of the paper P (reference position of each swing timing). The correction value of the swing control information (target position Tp, swing speed) in the above is calculated. The method of calculating the correction value is the same as that described in step S6 of FIG.

Then, the control unit 11 corrects the swing control information of the swing control table 121 based on the correction value calculated for each swing timing in the sub-scanning direction (step S27), and the corrected swing control information is used. The swing control table 121 is updated (step S28). That is, the calculated correction value is used to correct the swing control information of each swing timing of the swing control table 121 according to the conditions related to paper transport, and the corrected swing control table 121 is stored in the storage unit 12. Let me.

Here, even if the side end portion of the paper P is aligned with the target position Tp at the position of the position detection sensor SE2, the sub-scanning bend occurs as described above, and the image position shifts with respect to the paper P toward the rear end. Tends to increase. In particular, the deviation is remarkable for paper that is long in the paper transport direction, such as long paper. In the present embodiment, the swing control information at a plurality of positions corresponding to the plurality of swing timings in the sub-scanning direction of the paper P is corrected and stored in the swing control table 121. Therefore, the swing control information can be individually corrected based on the image deviation and noise at each position in the sub-scanning direction, and the deviation between the paper and the image position due to the sub-scan bending can be suppressed with high accuracy. It becomes. In addition, since the edges on the same side are always aligned, it is possible to suppress the influence of variations in the outer shape of the paper.

Next, the control unit 11 determines whether or not the transcription up to the final page is completed (step S29).
When it is determined that the transcription up to the final page has not been completed (step S29; NO), the control unit 11 returns to step S21.
When it is determined that the transfer up to the final page is completed (step S29; 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 based on the swing operation of the resist roller 27 during job execution. The image forming apparatus 100 sets the adjustment mode. In the adjustment mode, 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 of paper 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 the paper by the secondary transfer roller 9. Further, the control unit 11 causes the resist roller 27 to swing and the paper on which the image is transferred to be read by the image reading unit 60 under the same control as the shaking control process B, and the reading result by the image reading unit 60 is obtained. Based on this, 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 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.

As described above, according to the image forming apparatus 100, the control unit 11 swings the resist roller 27 based on the detection result detected by the position detection sensor SE2 and the swing control information determined in advance. The control is continuously performed not only before the paper P rushes into the secondary transfer roller 9 but also after the paper P rushes into the secondary transfer roller 9. Then, the image-transferred paper P that has passed through the secondary transfer roller 9 is read by the image reading unit 60, and the swing control information is corrected based on the reading result.
Therefore, even after the paper P has rushed into the secondary transfer roller 9, the position of the side end portion of the paper P is adjusted, and the swing control information is obtained based on the misalignment between the paper and the toner image after transfer. Since the correction is performed, it is possible to suppress the deviation of the image position with respect to the paper due to the sub-scanning bend with high accuracy.

For example, by correcting the swing control information used for swing control of the resist roller 27 before the paper rushes into the secondary transfer roller 9 based on the reading result by the image reading unit 60, the image position on the paper tip side is corrected. The deviation can be suppressed with high accuracy.

Further, for example, based on the reading result by the image reading unit 60, the swing control information used for swing control of the resist roller 27 after the paper has rushed into the secondary transfer roller 9 is corrected to correct the swing control information on the rear end side of the paper. It is possible to suppress the deviation of the image position in the image with high accuracy.

Further, for example, the correction value of the swing control information is determined based on the reading result by the image reading unit 60, and the determined correction value is stored in the storage unit 12, so that the correction value is obtained even after the next job or the power is turned off. Can be used. Further, for example, a table storing correction values of swing control information according to conditions related to paper transport such as a paper type, an environment, a paper surface forming an image, and a paper feed tray is stored in the storage unit 12. This makes it possible to perform optimum swing control according to the conditions related to paper transport.

Further, for example, a table storing swing control information according to conditions related to paper transport such as a paper type, an environment, a paper surface forming an image, and a paper feed tray is stored in a storage unit 12, and an image reading unit is stored. By correcting the swing control information according to the conditions related to paper transport stored in the table by the correction value determined based on the reading result by 60, the optimum swing control according to the conditions related to paper transport can be performed. It will be possible to do.

Further, the image forming apparatus 100 has an adjustment mode, and when an operation in the adjustment mode is instructed, the paper is automatically passed through, the image is transferred to the paper, and the image reading unit 60 reads the image. Since the swing control table 121 or the correction value table 122 is corrected based on the reading result, the swing control information and the correction value can be set to the optimum values in advance before the job is executed.

Further, by correcting each of a plurality of swing control information according to the timing of swinging the resist roller 27 based on the reading result by the image reading unit 60, the deviation of the image position with respect to the paper due to the sub-scanning bend is higher. It can be suppressed with 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 swing control processes A and B, a case where the control to swing the resist roller 27 when the paper side edge deviates from the target position Tp is performed until the paper P comes out of the resist roller has been described as an example. The timing of rocking control (detection of the paper side edge by the position detection sensor SE2 and rocking of the resist roller 27) is determined multiple times according to the paper length, and rocking is performed multiple times at a plurality of predetermined timings. Dynamic control may be performed.

Further, in the first and second embodiments, every time one page of an image is transferred, the paper P is read by the image reading unit 60, and the control unit 11 shakes in real time based on the reading result. Although the case of correcting the dynamic control information has been described as an example, the calculated value (for example, the average value of the deviation amount, the median value, etc.) of the reading result for a predetermined period (that is, the paper on which a plurality of images are transferred) is set. Based on this, the swing control information may be corrected. Thereby, the swing control information can be efficiently corrected based on the tendency of the predetermined period.

Further, in the swing control processes A and B, the swing control information used for swing control of the resist roller 27 on the next paper is corrected based on the reading result of the image reading unit 60 on the front paper during job execution. Although this case has been described as an example, 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 image reading unit 60 reads paper up to a predetermined size, the control unit 11 corrects the swing control information based on the reading result. 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 above embodiment, a color image forming apparatus for primary transfer of an image formed on a photoconductor drum to an intermediate transfer roller and transfer of an image from the intermediate transfer roller to paper by a 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 photoconductor drum to paper by a transfer roller.

Further, in the above embodiment, the position detection sensor SE2 is provided between the resist roller 27 and the secondary transfer roller 9, and the resist roller 27 swings based on the detection result of the paper side edge portion by the position detection sensor SE2. Although it has been described as controlling, it is also possible to directly control the swing of the resist roller 27 based on the reading result of the transferred paper by the image reading unit 60 without providing the position detection sensor SE2.

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 does not necessarily have to be. 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 embodiment, it is described that the resist roller 27 is shaken based on the detection result by the position detection sensor SE2 and the swing control information before and after the paper P is pushed into the secondary transfer roller 9. However, different swing control may be performed before the paper P enters the secondary transfer roller 9.

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. Further, 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 122 Correction value table 13 Communication unit 14 Operation unit SC Document reading device 10 Image forming unit 9 Secondary transfer roller 20 Paper transfer unit 27 Resist roller 50 Fixing device 60 Image Reader SE1 Resist sensor SE2 Position detection sensor SE3 Environmental sensor

Claims (10)

In an image forming apparatus that conveys paper to a transfer unit and transfers an image to the paper.
An oscillating roller composed of a pair of rollers that transport the conveyed paper toward the transfer unit, and
A detection unit arranged between the rocking roller and the transfer unit to detect the position of the side edge portion of the paper.
The rocking roller is controlled to swing before the paper rushes into the transfer portion and after the paper rushes into the transfer portion, and at least after the paper rushes into the transfer portion, the detection unit performs the swing control. A control unit that swings the swing roller based on the detected detection result and predetermined swing control information, and a control unit that swings the swing roller.
An image reading unit that reads the paper on which an image is transferred by passing through the transfer unit and acquires a scanned image including a region of the paper and an area of the image.
A correction unit that acquires the distance between the edge of the paper and the image from the scanned image acquired by the image reading unit and corrects the swing control information based on the acquired distance .
An image forming apparatus. The image according to claim 1, wherein the correction unit determines a correction value of the swing control information based on the distance acquired from the image read by the image reading unit, and stores the determined correction value in the storage unit. Forming device. The image forming apparatus according to claim 2, wherein the storage unit stores a table in which correction values of the swing control information are stored according to conditions related to paper transport. It is equipped with a storage unit that stores a table that stores the swing control information according to the conditions related to paper transport.
The correction unit determines a correction value of the swing control information based on the distance acquired from the image read by the image reading unit, and uses the determined correction value to obtain the swing control information stored in the table. The image forming apparatus according to claim 1. 3 . The image forming apparatus according to 4. The correction unit according to any one of claims 1 to 5, wherein the correction unit corrects the swing control information in real time based on the distance acquired from the scanned image each time the image reading unit reads the image. Image forming device. Claims 1 to 5 in which the correction unit corrects the swing control information based on the calculated value of the deviation amount based on the distance acquired from the scanned image acquired by the image reading unit in a predetermined period. The image forming apparatus according to any one of the above. The control unit performs the swing control based on a plurality of swing control information according to the timing of swinging the swing roller.
Any of claims 1 to 7, wherein the correction unit corrects a plurality of swing control information according to the timing of swinging the swing roller based on the distance acquired from the image read by the image reading unit. The image forming apparatus according to claim 1. The image forming apparatus according to any one of claims 1 to 8, wherein the swing roller swings in a direction orthogonal to the paper transport direction. An oscillating roller composed of a pair of rollers that transport the conveyed paper toward the transfer unit.
A detection unit arranged between the rocking roller and the transfer unit to detect the position of the side edge portion of the paper.
It is a control method of a rocking roller in an image forming apparatus provided with.
The paper is at least after the paper has rushed into the transfer portion by the control unit that controls the swing of the swing roller before the paper has rushed into the transfer portion and after the paper has rushed into the transfer portion. A process of swinging the swing roller based on the detection result detected by the detection unit and predetermined swing control information, and
A step of reading the paper on which an image is transferred by passing through the transfer unit by an image reading unit to acquire a scanned image including a region of the paper and a region of the image .
A step of acquiring the distance between the edge of the paper and the image from the scanned image acquired by the image reading unit and correcting the swing control information based on the acquired distance .
Control methods including.

Images