JP2022178142A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that avoids an image defect in an obliquely fed sheet.SOLUTION: An image forming apparatus 1 comprises: an exposure unit 11 that forms a latent image on a photoreceptor drum 13; a developing unit 12 that develops the latent image to form a toner image; a secondary transfer unit 27 that transfers the toner image to the sheet; a sheet conveyance path that conveys the sheet; a tip detection unit that detects the tip of the sheet to be conveyed; an end detection sensor 35 that detects an end position in a width direction of the sheet; a storage unit 42 that stores results of detection made by the tip detection unit and the end detection sensor; and a control unit 41 that controls an image forming position of the latent image formed on the photoreceptor drum 13. The end detection sensor 35 detects at least two or more end positions separated from each other in a conveyance direction. The control unit 41 corrects the image forming position based on the results of detection made by the tip detection unit and the end detection sensor 35.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus that forms a toner image on a photoreceptor.

2. Description of the Related Art Currently, in an electrophotographic image forming apparatus, a toner image is transferred from a photosensitive drum onto a sheet of paper via an intermediate transfer belt. 2. Description of the Related Art In an image forming apparatus, misalignment between a sheet and a toner image makes it impossible to form an image at an appropriate position on the sheet. Therefore, a sheet skew correction mechanism is known as a mechanism for aligning the positions of the sheet and the toner image. The skew correcting mechanism corrects the skew of the paper by abutting the leading edge of the paper against a registration roller arranged upstream of the transfer position. Also, regarding the skew correction mechanism, there has been proposed a method of expanding the range in which the positional deviation can be corrected (see, for example, Japanese Unexamined Patent Application Publication No. 2002-100002).

JP 2014-61989 A

The image forming apparatus described in Japanese Patent Application Laid-Open No. 2002-200010 includes correcting means for correcting misalignment of paper in the width direction, and first detecting means for detecting misalignment of the paper before the conveyed paper reaches the correcting means. a determining means for determining a correction direction for shifting the correcting means based on the detection result of the first detecting means; and a control means for pre-shifting the correcting means for shifting in a direction opposite to the correcting direction.

In the above-described image forming apparatus, misalignment of the paper is corrected by shifting the correcting means while holding the paper. However, if the paper is shifted in the width direction, it will be misaligned with the toner image. There was a fear that

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of avoiding image defects caused by obliquely fed paper.

An image forming apparatus according to the present invention is an image forming apparatus that forms a toner image on a photoreceptor, and includes an exposure unit that forms a latent image on the photoreceptor and a latent image that develops the latent image on the photoreceptor. a developing section for forming a toner image; a transfer section for transferring the toner image on the photoreceptor onto a sheet; a sheet conveying path for conveying the sheet to the transferring section; an edge detection section for detecting the leading edge of the paper, an edge detection sensor provided upstream of the edge detection section in the paper transport direction and detecting an edge position in the width direction of the sheet, and the edge detection and a storage unit for storing detection results of the end detection sensor and the end detection sensor, and a control unit for controlling an image forming position of the latent image formed on the photoconductor by the exposure unit, wherein At least two edge positions spaced apart in the conveying direction are detected, and the control unit corrects the image forming position based on the detection results of the leading edge detection unit and the edge detection sensor. and

In the image forming apparatus according to the present invention, the control unit estimates the skew of the conveyed paper based on the detection results of the leading edge detection unit and the edge detection sensor, and forms the image according to the skew of the paper. A configuration for correcting the position may be employed.

In the image forming apparatus according to the aspect of the invention, the storage unit stores the size of the conveyed paper in association with the detection result, and the control unit stores the size of the paper corresponding to the detection result and the size of the paper to be conveyed. When the size of the paper is different, the image forming position on the paper of the different size may be estimated from the inclination of the paper.

In the image forming apparatus according to the present invention, the control section may be configured to keep the image forming positions constant between the adjacent end positions.

In the image forming apparatus according to the present invention, the storage unit stores a plurality of detection results of the leading edge detection unit and the edge detection sensor for a plurality of sheets, and the control unit stores the plurality of detection results. The image forming position may be corrected based on the average value of the results.

In the image forming apparatus according to the present invention, the control section may update the detection results stored in the storage section when the leading edge detection section and the edge detection sensor output detection results.

According to the present invention, by correcting the position at which the latent image is formed on the skewed paper, it is possible to avoid image defects such as the image being misaligned with the paper and the paper being partially cut off.

1 is a schematic side view of an image forming apparatus according to an embodiment of the invention; FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention; FIG. FIG. 2 is a schematic explanatory diagram showing the relationship between the image forming position of the latent image on the photosensitive drum and the paper conveyed on the paper conveying path. FIG. 3 is a schematic explanatory diagram showing the relationship between the image forming position of the latent image on the photoreceptor drum and the sheet fed obliquely. FIG. 4 is a schematic explanatory diagram showing the positional relationship between a sheet conveyed on a sheet conveying path and an edge detection sensor; FIG. 11 is an explanatory diagram showing an example of a detection result of end positions; FIG. 10 is an explanatory diagram showing a sheet on which a corrected image is formed; FIG. 3 is a flowchart showing a control flow when forming an image with the image forming apparatus according to the present embodiment;

An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic side view of an image forming apparatus according to an embodiment of the invention.

The image forming apparatus 1 forms multicolor and monochromatic images on a predetermined sheet of paper in accordance with image information transmitted from the outside. The image forming apparatus 1 includes an exposure section 11, a development section 12, a photoreceptor drum 13 (an example of a photoreceptor), a cleaner device 14, a charger 15, an intermediate transfer belt device 16, a fixing device 17, a paper feed tray 18, and a paper discharge. It is configured to include a tray 19 and a sheet conveying device 20 .

The image data handled by the image forming apparatus 1 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, four developing units 12, photosensitive drums 13, chargers 15, and cleaning devices 14 are provided so as to form four types of latent images corresponding to the respective colors, respectively black, cyan, magenta, and yellow. , and these constitute four image stations.

The photosensitive drum 13 is arranged substantially in the center of the image forming apparatus 1 and is rotationally driven by a connected drive source (not shown). The charger 15 uniformly charges the surface of the photosensitive drum 13 to a predetermined potential. The exposure unit 11 exposes the surface of the photosensitive drum 13 to form an electrostatic latent image (latent image). The developing unit 12 develops the electrostatic latent image on the surface of the photoreceptor drum 13 to form a toner image on the surface of the photoreceptor drum 13 . Through the series of operations described above, a toner image of each color is formed on the surface of each photoreceptor drum 13 , and the toner image on the photoreceptor drum 13 is transferred onto the intermediate transfer belt 21 . The cleaner device 14 removes and collects residual toner on the surface of the photosensitive drum 13 after development and image transfer.

The intermediate transfer belt device 16 is arranged above the photosensitive drum 13 and includes an intermediate transfer belt 21 , a transfer drive roller 22 , a transfer driven roller 23 , a transfer pressure contact roller 24 and an intermediate transfer belt cleaning device 25 . Four transfer pressure contact rollers 24 are provided corresponding to the image stations of each color for YMCK.

The intermediate transfer belt 21 is stretched and supported by a transfer driving roller 22 , a transfer driven roller 23 , and a transfer pressing roller 24 . The transfer drive roller 22 is connected to a drive source and rotationally driven to rotate the intermediate transfer belt 21 in the arrow C direction. An intermediate transfer belt cleaning device 25 removes and collects residual toner from the intermediate transfer belt 21 , and the toner images of the respective colors formed on the surfaces of the photosensitive drums 13 are sequentially transferred and superimposed to form the intermediate transfer belt 21 . A color toner image is formed on the surface.

The image forming apparatus 1 further includes a secondary transfer section 27 including a transfer roller 27a and a secondary transfer belt 27b. The secondary transfer belt 27b is stretched and supported by the transfer roller 27a. In addition to the transfer roller 27a, a plurality of rollers for stretching the secondary transfer belt 27b may be provided. The transfer roller 27a is provided at a position facing the transfer drive roller 22, and a transfer nip portion is formed between the transfer roller 27a and the intermediate transfer belt 21 via the secondary transfer belt 27b. The incoming sheet P is nipped in the transfer nip portion and conveyed. The toner image on the surface of the intermediate transfer belt 21 is transferred to the paper P while passing through the transfer nip portion.

The paper feed tray 18 is a tray for storing paper P used for image formation, and is provided below the exposure section 11 . Also, the paper discharge tray 19 is provided in the upper part of the image forming apparatus 1 and is a tray for placing paper P on which an image has been formed.

Further, the image forming apparatus 1 is provided with a paper conveying device 20 for conveying the paper P from the paper feed tray 18 to the paper discharge tray 19 via the secondary transfer portion 27 and the fixing device 17 . The paper conveying device 20 has an S-shaped paper conveying path S. Along the paper conveying path S, there are a pickup roller 31, a pair of separation rollers 31a and 31b, a registration roller 32, a pre-registration roller 33, and a fixing device 17. , and a discharge roller 34 are arranged.

The pickup roller 31 is provided near the end of the paper feed tray 18 and is a pickup roller that feeds the paper P from the paper feed tray 18 to the paper transport path S one by one. One separation roller 31a passes the paper P between itself and the other separation roller 31b, and conveys the paper P to the paper conveyance path S while separating the paper one by one. The registration roller 32 temporarily holds the paper P conveyed from the paper feed tray 18, and conveys the paper P to the transfer roller 27a at the timing when the leading edge of the toner image on the photosensitive drum 13 and the leading edge of the paper P are aligned. . The pre-registration rollers 33 are small rollers for promoting and assisting the transportation of the paper P. As shown in FIG.

The fixing device 17 is of a belt fixing type. A fixing belt 173 is wound around a fixing roller 171 and a heating roller 172 , and a pressure roller 174 is pressed against the fixing roller 171 via the fixing belt 173 . ing. The fixing device 17 receives the paper P on which the unfixed toner image is formed, and conveys the paper P while sandwiching it between the fixing belt 173 and the pressure roller 174 . After fixing, the paper P is discharged onto the paper discharge tray 19 by the paper discharge rollers 34 . Although the fixing device 17 is a belt fixing type fixing device, the fixing device 17 is not limited thereto, and may be a type in which the pressure roller 174 directly presses the fixing roller 171 .

Photoreceptor drum 13 and transfer drive roller 22 may not be directly connected to a drive source, and a gear or clutch may be interposed therebetween so that photoreceptor drum 13 and transfer drive roller 22 can be driven at different speeds. , or may be driven at different timings.

An edge detection sensor 35 is arranged between the pre-registration roller 33 and the registration roller 32 in the paper transport path S. As shown in FIG. The edge detection sensor 35 is a line sensor having a plurality of detection elements arranged side by side along the width direction W of the paper P. As shown in FIG. The position of the edge detection sensor 35 with respect to the paper P transported on the paper transport path S will be described later with reference to FIG.

In the present embodiment, the registration rollers 32 are used as a leading edge detection section that detects the leading edge Pa (see FIG. 3 described later) of the sheet P being conveyed. That is, the leading edge Pa of the paper P can be detected when the paper P transported on the paper transport path S reaches the registration rollers 32 . The present invention is not limited to this, and a sensor provided along the paper transport path S may be used as the leading edge detection section. The leading edge detection unit may be an optical sensor that does not contact the paper P, or a contact sensor that uses an actuator that is pressed by the leading edge Pa of the paper P and swings. When the sensor is used as the leading edge detection section, the sensor may be provided downstream of the edge detection sensor 35 in the direction in which the paper P is conveyed.

FIG. 2 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the invention.

The image forming apparatus 1 includes a control section 41 and a storage section 42 in addition to the photosensitive drum 13 , exposure section 11 , secondary transfer section 27 , registration rollers 32 , and edge detection sensor 35 described above. 2, only a part of the image forming apparatus 1 is shown, and the rest is omitted.

The storage unit 42 stores detection results of the leading edge detection unit and the edge detection sensor 35 . When storing the detection result of the edge detection sensor 35, the storage unit 42 may store the detection result in association with the size of the paper P transported on the paper transport path S and the like.

The control unit 41 controls the image forming position of the latent image formed on the photosensitive drum 13 by the exposure unit 11 . The image forming position of the latent image on the photosensitive drum 13 will be described in conjunction with FIG. 3 described later.

FIG. 3 is a schematic explanatory diagram showing the relationship between the image forming position of the latent image on the photosensitive drum and the paper conveyed on the paper conveying path.

In FIG. 3, the latent image formed on the photosensitive drum 13 is shown in the width direction W with respect to the registration roller 32 and the paper P so that the position of the latent image formed on the photosensitive drum 13 when it reaches the transfer nip portion via the intermediate transfer belt 21 and the like can be seen. The positional relationship of is shown schematically.

The exposure unit 11 has a light source 11a, a mirror 11b, a rotating polygon mirror 11c, and a laser sensor 11d. In addition, in FIG. 3, a part of the exposure unit 11 is extracted and shown, and other parts may be included. The light source 11a irradiates the laser beam BM toward the mirror 11b. The mirror 11b reflects the laser beam BM toward the rotary polygon mirror 11c. The rotating polygon mirror 11c is a mirror having a plurality of surfaces around a rotation axis, and rotates in the rotation direction R to scan the incident laser beam BM in the scanning direction S. As shown in FIG. The laser beam BM scanned by the rotating polygon mirror 11c is incident on the laser sensor 11d after scanning the surface of the photosensitive drum 13. As shown in FIG. The laser sensor 11d detects the output of the incident laser beam BM. The photosensitive drum 13 has a rotating shaft arranged parallel to the width direction W of the paper P, and the scanning direction S of the laser beam BM corresponds to the width direction W. As shown in FIG.

In the exposure unit 11, when the photoreceptor drum 13 is irradiated with the laser beam BM, the output of the laser beam BM is adjusted to adjust the output of the laser beam BM from the write start position BP1 to the write end position BP2 on the surface of the photoreceptor drum 13. A latent image is formed in the That is, the writing start position BP1 to the writing end position BP2 correspond to the image forming positions of the latent image formed on the photosensitive drum 13 by the exposure unit 11 . In the exposure unit 11, the writing start position BP1 and the writing end position BP2 can be shifted by changing the timing for adjusting the output of the laser beam BM. The first image line BL1 shown in FIG. 3 is a straight line corresponding to the writing start position BP1, and the second image line BL2 is a straight line corresponding to the writing end position BP2. That is, the latent image formed on the photosensitive drum 13 is positioned between the first image line BL1 and the second image line BL2 when it reaches the transfer nip portion.

The writing start position BP1 and the writing end position BP2 are determined based on the margin SP on the paper P. FIG. The paper P is provided with a margin SP in which no image is formed on the peripheral edge, and in the width direction W, the space from the first image line BL1 or the second image line BL2 to the side edge Pb is the margin SP. That is, by adjusting the positions of the writing start position BP1 and the writing end position BP2, the paper P is provided with a margin SP having a predetermined width.

FIG. 4 is a schematic explanatory diagram showing the relationship between the image forming position of the latent image on the photoreceptor drum and the sheet fed obliquely.

FIG. 4 differs from FIG. 3 in that the sheet P is skewed. In the state shown in FIG. 4, the paper is fed obliquely and the side edge Pb is slanted. Therefore, the width of the margin SP varies between the leading edge Pa and the trailing edge, and part of the image may protrude from the paper. There is The present embodiment aims to eliminate image misalignment by correcting the position where the latent image is formed on the sheet P that has been skewed as shown in FIG.

3 and 4 show the case where the writing start position BP1 and the writing end position BP2 are not moved when forming a latent image on one sheet of paper P, and the first image line BL1 and the second image line BL1 are not moved. Although BL2 is a straight line, the first image line BL1 and the second image line BL2 are displaced in the width direction W by moving the writing start position BP1 and the writing end position BP2. In this embodiment, in order to determine the writing start position BP1 and the writing end position BP2, the edge position (side edge Pb) of the paper P in the width direction W is detected by the edge detection sensor 35 .

Next, a method for determining the write start position BP1 and the write end position BP2 from the detected end positions will be described with reference to FIGS. 5 and 6. FIG.

FIG. 5 is a schematic explanatory diagram showing the positional relationship between the paper conveyed on the paper conveying path and the edge detection sensor.

The edge detection sensor 35 is provided at a position facing the periphery of one edge of the sheet P in the width direction W in the sheet conveying path S. As shown in FIG. A reference position is set in the width direction W of the edge detection sensor 35 . In the image forming apparatus 1, the edge detection sensor 35 is fixed, and the paper P is transported in the transport direction H. Therefore, in FIG. For the sake of illustration, a reference line CL extending in the transport direction H from the reference position is shown.

Next, the case of detecting the edge positions of an A3 sheet of paper P whose length (total length PL) in the transport direction H is 420 mm will be described. The edge detection sensor 35 measures the distance (initial distance Δ0) from the reference line CL to the side edge Pb of the paper P at an initial point KP0 a predetermined distance (margin distance ML) away from the leading edge Pa of the paper P. Thereafter, the distance from the side edge Pb of the paper P to the reference line CL is measured every time the initial point KP0 is separated from the initial point KP0 by a predetermined distance. Specifically, in the case of A3 paper, the first detection point KP1 is set at a distance of 100 mm from the initial point KP0, and the second detection point KP2, the third detection point KP3, and the fourth detection point KP3 are set at intervals of 100 mm. A point KP4 is set. Then, the distances (first distance Δ1 to fourth distance Δ4) from the reference line CL to the side edge Pb of the paper P are measured at the first detection point KP1 to the fourth detection point KP4. In this way, the edge position of the paper P in the width direction W is detected by measuring the distance (first distance Δ1 to fourth distance Δ4) from the reference position (reference line CL) in the width direction W. be able to.

FIG. 6 is an explanatory diagram showing an example of the detection result of the end position.

In FIG. 6, the horizontal axis indicates the position in the transport direction H, the vertical axis indicates the position in the width direction W, and the distance from the reference line CL to the side edge Pb of the paper P increases upward. is increasing. In the example shown in FIG. 6, the distance from the reference line CL to the side edge Pb of the paper P gradually increases from the initial point KP0 toward the fourth detection point KP4. For the sake of explanation, the results of measurements at the initial point KP0 to the fourth detection point KP4 may be referred to as measurement points hereinafter.

A first correction line TL1 shown in FIG. 6 is a curve that smoothly connects the measurement points. In addition, the second correction line TL2 is a line that connects adjacent points in a stepped manner with a constant value between adjacent points at the initial point KP0 to the fourth detection point KP4. For example, on the second correction line TL2, the position in the width direction W is a constant value based on the average value of both from the initial point KP0 to the first detection point KP1. Similarly, between the first detection point KP1 and the second detection point KP2, a constant value is set based on the average value of both, and the positions in the width direction W are determined in the same manner for the other points.

FIG. 7 is an explanatory diagram showing a sheet on which a corrected image is formed.

FIG. 7 shows the sheet P with the trailing edge side (the right side in FIG. 7) being curved. The control unit 41 sets the image forming position so that the image GZ is curved according to the paper P. FIG. Specifically, in the curved portion of the paper P, the first interval Δ1 to the fourth interval Δ4 are displaced as in the example shown in FIG. 6 . Therefore, the control unit 41 can curve the image GZ by changing the image forming position like the first correction line TL1 or the second correction line TL2.

In this manner, the control unit 41 estimates the skew of the conveyed paper based on the detection results of the leading edge detection unit and the edge detection sensor 35, and corrects the image forming position according to the skew of the paper. Therefore, by correcting the position where the latent image is formed on the skewed sheet P, it is possible to avoid image defects such as the image GZ and the sheet P being partially cut off due to misalignment. Further, by estimating the inclination of the sheet P as in the case of the first correction line TL1, it is possible to correct the image forming position even in a portion where the edge position is not detected, and make the deviation of the image GZ due to the inclination less noticeable. can. Furthermore, even in a portion where the edge position is not detected, such as the second correction line TL2, by setting a constant image forming position based on the detection result, it is possible to correct image misalignment.

FIG. 8 is a flowchart showing a control flow when forming an image with the image forming apparatus according to this embodiment.

In the control flow shown in FIG. 8, execution of image formation is instructed at the start of processing.

In step S01, the control unit 41 reads image information. The control unit 41 instructs the exposure unit 11 to form a latent image according to the read image information.

In step S02, the control unit 41 performs image forming position setting processing. When setting the image forming position, the image forming position stored in advance in the storage unit 42 may be applied. Further, when a predetermined time has passed since the previous image formation, the image forming position may be initialized to a predetermined value.

In step S03, the paper P is transported through the paper transport path S. As shown in FIG. In conveying the paper P, the timing may be appropriately adjusted by the registration rollers 32 so as to match the toner image formed on the intermediate transfer belt 21 .

In step S<b>04 , the edge position of the paper P is detected by the edge detection sensor 35 .

In step S<b>05 , the detected end positions are stored in the storage unit 42 .

In step S06, the control unit 41 performs correction processing of the image forming position. Specifically, the image forming position is corrected based on the end positions stored in step S05. In correcting the image forming position, the image forming position is set according to the end position, like the first correction line TL1 and the second correction line TL2 shown in FIG. Thereafter, an image is formed on the paper P by forming and transferring a toner image.

In step S07, the controller 41 determines whether or not there is another sheet for image formation next. As a result, if there is a sheet for image formation next (step S07: YES), the process returns to step S02 and repeats the processes up to step S06. On the other hand, if there is no sheet for image formation next (step S07: NO), the process ends.

In the correction processing of the image forming position, the image forming position may be corrected based on the average value of the detection results detected for a plurality of sheets. When performing such processing, the storage unit 42 stores detection results for a plurality of sheets. The control unit 41 calculates the average value for each point (initial point KP0 to fourth detection point KP4). Note that the number of sheets P for which the average value is to be calculated may be set as appropriate. good. By calculating based on the average value of the detection results in this manner, the image forming position can be obtained with high accuracy.

Further, in the image forming position correction process, the control section 41 may update the detection results stored in the storage section when the leading edge detection section and the edge detection sensor 35 output the detection results. In this way, by updating to the detection result during the image forming operation, it is possible to improve the correction accuracy in the next job.

The first correction line TL1 shown in FIG. 6 is a curve connecting all the measurement points from the initial point KP0 to the fourth detection point KP4, but is not limited to this, and the initial point KP0 to the fourth detection point KP4. Of these, the correction line may be set based on a straight line passing through two measurement points. Thus, the inclination of the paper P may be estimated from two measurement points. In this case, it is sufficient to detect the edge position only at two points, and it is not necessary to detect the edge position at other points.

Further, when the size of the paper P corresponding to the detection result stored in the storage unit 42 is different from the size of the paper P to be conveyed, the image forming position on the different size paper P is estimated from the inclination of the paper P. may For example, the detection result for A4 paper is stored, and when the A3 paper is conveyed, the inclination of the paper (first correction line TL1, etc.) estimated from the detection result for A4 paper is set to the total length PL of the A3 paper P. to set the image forming position. In this way, by estimating the image forming position from the inclination of the paper P of different sizes, it is possible to cope with the size of the paper P that has not been measured.

In addition, the embodiment disclosed this time is an example in all respects, and does not serve as a basis for a restrictive interpretation. Therefore, the technical scope of the present invention is not to be interpreted only by the above-described embodiments, but is defined based on the description of the claims. In addition, all changes within the meaning and range of equivalence to the claims are included.

REFERENCE SIGNS LIST 1 image forming apparatus 11 exposure section 12 development section 13 photoreceptor drum (an example of a photoreceptor)
27 Secondary transfer unit (an example of a transfer unit)
32 registration roller (an example of the leading edge detector)
35 Edge detection sensor 41 Control unit 42 Storage unit S Paper transport path

Claims (6)

An image forming apparatus for forming a toner image on a photoreceptor,
an exposure unit that forms a latent image on the photoreceptor;
a developing unit that develops the latent image on the photoreceptor to form a toner image;
a transfer unit that transfers the toner image on the photoreceptor to paper;
a paper transport path for transporting paper to the transfer unit;
a leading edge detection unit that is provided along the paper transport path and detects the leading edge of the transported paper;
an edge detection sensor provided on the upstream side of the leading edge detection unit in the paper transport direction and detecting an edge position in the width direction of the paper;
a storage unit that stores detection results of the tip detection unit and the edge detection sensor;
a control unit for controlling an image forming position of the latent image formed on the photoreceptor by the exposure unit;
The edge detection sensor detects at least two edge positions spaced apart in the conveying direction,
The image forming apparatus, wherein the control section corrects the image forming position based on the detection results of the leading edge detection section and the edge detection sensor. The image forming apparatus according to claim 1,
The control unit estimates the skew of the conveyed paper based on the detection results of the leading edge detection unit and the edge detection sensor, and corrects the image forming position according to the skew of the paper. Image forming device. The image forming apparatus according to claim 2,
The storage unit associates and stores the size of the conveyed sheet and the detection result,
wherein, when the paper size corresponding to the detection result is different from the size of the paper to be conveyed, the control unit estimates the image forming position on the different size paper from the inclination of the paper. forming device. The image forming apparatus according to claim 1,
The image forming apparatus, wherein the control unit keeps the image forming position constant between the adjacent end positions. The image forming apparatus according to any one of claims 1 to 4,
The storage unit stores a plurality of detection results of the leading edge detection unit and the edge detection sensor detected with respect to a plurality of sheets,
The image forming apparatus, wherein the control unit corrects the image forming position based on an average value of the plurality of detection results. The image forming apparatus according to any one of claims 1 to 5,
The image forming apparatus, wherein the control unit updates the detection results stored in the storage unit when the leading edge detection unit and the edge detection sensor output detection results.

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