JP2018013703A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which can accurately correct an error caused by wear of a sensor piece.SOLUTION: An image forming apparatus 1 includes an image forming section 3, a conveyance section 5, a sensor 56 and a control section 9. The sensor 56 has a sensor piece 56a and a detection section 56c. The sensor piece 56a abuts on a sheet S and is tilted from an initial position, and is separated from the sheet S and is returned to the initial position. The detection section 56c outputs a detection signal indicating that the sensor piece 56a is tilted. The control section 9 has an operation control section 91, a measurement section 92 and a correction section 93. The measurement section 92 measures a time at which a detection signal is output from the detection section 56c, and generates a detection time. The correction section 93 corrects such a timing that the operation control section 91 controls the operations of the image formation section 3 and the conveyance section 5 based on a difference between the detection time and a reference time.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an image forming apparatus.

  The image forming apparatus described in Patent Document 1 includes a registration roller, a registration sensor, an image forming unit, a control unit, and a storage unit. The registration rollers are temporarily stopped to form a bend in the paper being conveyed. As a result, the paper whose posture is corrected is conveyed. The registration sensor is arranged on the upstream side of the registration roller in the paper conveyance path. The resist sensor has a sensor section and a detection unit. The sensor slice comes into contact with the leading edge of the paper and tilts from the initial position. After the sensor piece slides on the back surface of the sheet, the sensor piece moves away from the rear end of the sheet and returns to the initial position. The detection unit detects the tilt of the sensor slice and outputs a detection signal.

  The image forming unit forms an image on a sheet. Based on the detection signal, the control unit controls the registration roller and the image forming unit so that the sheet conveyance timing coincides with the image formation timing. The storage unit stores the correction value. The correction value is a value for correcting an error due to wear occurring in the sensor intercept. The correction value is set in advance for each operation amount of the image forming apparatus, that is, for each predetermined number of conveyed sheets. The sensor slice is worn by sliding with the paper.

JP 2011-175165 A

  In the image forming apparatus described in Patent Document 1, a correction value is added to the timing at which the registration roller and the image forming unit are operated when the number of conveyed sheets is equal to or greater than a predetermined value. As a result, the error due to wear of the sensor segment is corrected. However, there is still room for improvement in terms of correcting the error due to wear of the sensor section more accurately.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of more accurately correcting an error due to wear of a sensor section.

  An image forming apparatus according to the present invention includes an image forming unit, a transport unit, a sensor, and a control unit. The image forming unit forms an image on a recording medium conveyed along a conveyance path. The transport unit transports the recording medium along the transport path. The sensor detects the recording medium transported by the transport unit. The control unit controls the image forming unit and the transport unit. The sensor includes a sensor section and a detection unit. The sensor piece abuts on the tip of the recording medium and tilts from an initial position. The sensor segment is separated from the rear end of the recording medium and returns to the initial position. The detection unit outputs a detection signal indicating that the sensor slice is tilted. The control unit includes an operation control unit, a measurement unit, and a correction unit. The operation control unit controls operations of the image forming unit and the transport unit based on the detection signal. The measurement unit measures a time during which the detection signal is continuously output, and generates a detection time. The correction unit corrects a timing at which the operation control unit controls operations of the image forming unit and the conveyance unit based on a difference between the detection time and a reference time.

  According to the image forming apparatus of the present invention, it is possible to more accurately correct an error due to wear of the sensor section.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a transport unit on the upstream side of the image forming unit in FIG. 1. It is a figure which shows the time of the initial stage operation | movement of the sensor intercept of FIG. FIG. 3 is a diagram illustrating an initial wear state of the sensor section of FIG. 2. It is a figure which shows the time of medium-term wear of the sensor slice of FIG. It is a figure which shows the wear end stage of the sensor slice of FIG. FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus in FIG. 1. It is a flowchart which shows the correction control of the control part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 1 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment is a multifunction machine. The image forming apparatus 1 may be a copy, a printer, or a facsimile. The multi-function peripheral has, for example, at least two functions among a copy function, a printer function, and a facsimile function.

  The image forming apparatus 1 includes a housing 2, an image forming unit 3, a fixing unit 4, a transport unit 5, a storage unit 6, a discharge tray 7, an operation panel 8, a control unit 9, and a storage unit 10. With. In FIG. 1, the direction in which the operation panel 8 faces is defined as the front, and the front-rear direction is defined. Further, the left-hand side is defined as the left side toward the front of the image forming apparatus 1, and the left-right direction is defined. Further, the front-rear direction and the direction orthogonal to the left-right direction are defined as the up-down direction.

  The operation panel 8 includes a display unit 81 and an input unit 82. The display unit 81 includes a display. The display includes an LCD (Liquid Crystal Display) having a touch panel function, or an organic ELD (Electro Luminescence Display). The display unit 81 displays various setting screens of the image forming apparatus 1. Input unit 82 includes hard keys. The input unit 82 generates an operation signal corresponding to a user operation. User operations include, for example, operations for performing various settings of the image forming apparatus 1.

  The image forming apparatus 1 forms an image on the paper S. The paper S is an example of the recording medium of the present invention. The paper S is, for example, plain paper, copy paper, recycled paper, thin paper, thick paper, glossy paper, or OHP (Overhead Projector) paper. The paper S is conveyed from the storage unit 6 to the discharge tray 7 along the paper conveyance path.

  The housing 2 is formed in a box shape having a rectangular bottom surface. The housing 2 houses an image forming unit 3, a fixing unit 4, a transport unit 5, a storage unit 6, a control unit 9, and a storage unit 10.

  The storage unit 6 is disposed at the lower part of the housing 2. The storage unit 6 includes a paper feed cassette 61. The paper feed cassette 61 is detachable from the lower part of the housing 2. The paper feed cassette 61 is formed in a box shape with an open top. The paper feed cassette 61 can accommodate a plurality of paper S. The storage unit 6 may further include a manual feed tray. A plurality of sheets S can be placed on the manual feed tray.

  The image forming unit 3 is disposed on the downstream side of the storage unit 6 in the paper transport path. The image forming unit 3 is disposed above the storage unit 6 in the housing 2. The image forming unit 3 forms a toner image on the paper S. The image forming unit 3 includes a photosensitive drum 31, a charging unit 32, an exposure unit 33, a developing unit 34, a transfer unit 35, and a cleaning unit 36.

  The photosensitive drum 31 is rotatably arranged. The photosensitive drum 31 includes, for example, a conductive substrate and a photosensitive layer. The conductive substrate has conductivity. The photosensitive layer is formed on the outer peripheral surface of the conductive substrate. The charging unit 32 charges the photosensitive drum 31 to a predetermined potential. The exposure unit 33 irradiates a laser on the outer peripheral surface of the charged photosensitive drum 31 to form an electrostatic latent image. The developing unit 34 develops the electrostatic latent image as a toner image. As a result, a toner image is formed on the outer peripheral surface of the photosensitive drum 31.

  The transfer unit 35 transfers the toner image formed on the outer peripheral surface of the photosensitive drum 31 onto the paper S. The cleaning unit 36 removes residual toner adhering to the photosensitive drum 31 after the toner image is transferred.

  The fixing unit 4 is disposed on the downstream side of the image forming unit 3 in the paper conveyance path. The fixing unit 4 is disposed in front of the image forming unit 3 in the housing 2. The fixing unit 4 fixes the toner image transferred to the paper S. The fixing unit 4 includes a fixing roller 41 and a pressure roller 42. The fixing roller 41 has a heat source for heating the paper S. The pressure roller 42 forms a fixing nip with the fixing roller 41. The fixing unit 4 heats and presses the paper S that passes through the fixing nip to fix the toner image on the paper S. The sheet S on which the toner image is fixed is discharged to the discharge tray 7.

  The transport unit 5 transports the paper S along the paper transport path. The transport unit 5 has a plurality of rollers arranged along the paper transport path. The plurality of rollers include a registration roller 51, an intermediate roller 52, a feed roller 53, a transport roller 54, and a pickup roller 55.

  The pickup roller 55 takes out the paper S from the paper feed cassette 61 by rotating in contact with the upper surface of the paper S. The feed roller 53 is disposed on the downstream side of the pickup roller 55 in the paper transport path. The feed roller 53 sends out the paper S taken out by the pickup roller 55 to the downstream side of the paper transport path.

  The intermediate roller 52 is disposed on the downstream side of the feed roller 53 in the paper transport path. The intermediate roller 52 sends the paper S sent by the feed roller 53 to the registration roller 51. The transport roller 54 is disposed between the intermediate roller 52 and the feed roller 53 when the distance between the intermediate roller 52 and the feed roller 53 is larger than a predetermined length. The transport roller 54 sends the paper S sent by the feed roller 53 to the intermediate roller 52.

  The registration roller 51 corrects the posture of the paper S sent out by the intermediate roller 52. Specifically, the registration roller 51 is temporarily stopped and comes into contact with the leading end of the sheet S sent out by the intermediate roller 52. As a result, the paper S is bent so that the leading edge of the paper S is aligned. The registration roller 51 can correct the posture of the paper S by forming a bend in the paper S. Further, the registration roller 51 sends the sheet S to the image forming unit 3 after forming the deflection on the sheet S.

  FIG. 2 is an enlarged view schematically showing the transport unit 5 on the upstream side of the image forming unit 3. As shown in FIG. 2, the transport unit 5 further includes a registration sensor 56. The resist sensor 56 is an example of the sensor of the present invention. The registration sensor 56 detects the leading edge and the trailing edge of the paper S. The registration sensor 56 is a contact type that contacts the paper S conveyed by the conveyance unit 5.

  The resist sensor 56 includes a sensor section 56a, a support part 56b, and a detection part 56c. The sensor slice 56a is formed in a long shape. The sensor slice 56a is made of plastic, for example. The sensor slice 56a is supported by the support portion 56b. The tip of the sensor piece 56a protrudes into the paper transport path.

  The support part 56b supports the sensor slice 56a so that it can tilt. The support portion 56b supports the sensor slice 56a so as to be tiltable from the initial position T. The support portion 56b supports the sensor slice 56a along the direction orthogonal to the paper transport path at the initial position T. The support part 56b supports the sensor slice 56a so as to be tiltable in the transport direction of the paper S. The support portion 56b has an urging portion (not shown) inside. The biasing unit returns the tilted sensor section 56a to the initial position T.

  The detection unit 56 c outputs a detection signal to the control unit 9. The detection unit 56c includes a light emitting unit and a light receiving unit. The light emitting unit and the light receiving unit are arranged with the sensor slice 56a interposed therebetween. The light emitting unit emits light to the light receiving unit. The light emitted from the light emitting unit is blocked when the sensor slice 56a is tilted at a predetermined angle. The light receiving unit outputs a detection signal indicating the tilt of the sensor slice 56a to the control unit 9 when the light emitted from the light emitting unit is blocked. Further, the light receiving unit stops outputting the detection signal when receiving the light emitted from the light emitting unit.

  In the registration sensor 56 of this embodiment, the sheet S and the sensor piece 56a abut. The sensor slice 56a is in contact with the leading edge of the sheet S and tilted from the initial position T. The sensor piece 56a is separated from the rear end of the paper S after sliding with the paper S. The sensor piece 56a is separated from the paper S and returned to the initial position T. Further, the sensor piece 56a is worn when sliding with the paper S.

  FIG. 3 is a diagram illustrating an initial operation of the sensor piece 56a. The sensor intercept 56a shown in FIG. 3 is located at the initial position T and is indicated by a chain line. As shown in FIG. 3, the sensor slice 56a is formed in a substantially rectangular shape in a side view. The sensor intercept 56a has a vertex P1 and a vertex P2. The vertex P1 is located on the downstream side of the vertex P2 in the paper transport path. When the sensor piece 56a comes into contact with the sheet S during the initial operation, the sensor piece 56a is tilted by the angle α from the initial position T and transitions to the initial tilt position T1. Further, the sensor intercept 56a returns from the initial tilt position T1 to the initial position T when the apex P1 and the rear end S1 of the paper S are separated.

  FIG. 4 is a diagram showing the initial wear of the sensor segment 56a. The sensor intercept 56a shown in FIG. 4 is located at the initial position T and the initial tilt position T1 during the initial operation, and is indicated by a chain line. Here, the initial wear region is a region from a region where wear occurs at the vertex P2 to a region where wear occurs at the vertex P1. As shown in FIG. 4, in the sensor segment 56a, the area of wear increases from the vertex P2 toward the vertex P1. When the sensor piece 56a comes into contact with the paper S during initial wear, the sensor piece 56a is tilted from the initial position T by the angle α and transitions to the initial tilt position T1. Therefore, the sensor piece 56a at the initial wear is separated from the paper S at the same position as the sensor piece 56a at the initial operation.

  FIG. 5 is a diagram showing the middle period of wear of the sensor slice 56a. In FIG. 5, the sensor intercept 56a is located at the initial position T and the initial tilt position T1 during the initial operation, and is indicated by a chain line. Here, the medium-term wear region is a region from the region where the wear has occurred at the apex P1 to the region where the wear expands thereafter. As shown in FIG. 5, the wear area of the sensor slice 56a increases in the longitudinal direction of the sensor slice 56a. When the sensor piece 56a comes into contact with the paper S during the medium-term wear, it tilts by an angle β from the initial position T and transitions to the medium-term tilt position T2. The angle β is smaller than the angle α. Therefore, the sensor piece 56a at the time of middle-term wear is separated from the paper S earlier than the sensor piece 56a at the time of initial operation. During the medium-term wear, the position at which the sensor piece 56a and the paper S are separated from each other sequentially moves to the upstream side of the paper conveyance path as the wear area of the sensor piece 56a increases. As a result, at the time of middle-term wear, the timing at which the detection unit 56c described with reference to FIG. 2 stops outputting the detection signal is sequentially advanced as the wear area of the sensor segment 56a is enlarged.

  FIG. 6 is a diagram showing end-stage wear of the sensor section 56a. The sensor intercept 56a shown in FIG. 6 is located at the initial position T and the initial tilt position T1 during the initial operation, and is indicated by a chain line. Here, the end-stage wear area is an area when the middle-stage wear area is expanded to a predetermined area. As shown in FIG. 6, when the sensor piece 56a comes into contact with the paper S during the last stage wear, the sensor piece 56a is tilted by the angle γ from the initial position T and transitions to the last stage tilt position T3. The angle γ is a predetermined angle. There is a possibility that the sensor section 56a at the time of final wear cannot be detected by the detection unit 56c.

  FIG. 7 is a block diagram illustrating a configuration of the image forming apparatus 1. As shown in FIG. 7, the control unit 9 controls the image forming unit 3, the fixing unit 4, the transport unit 5, and the display unit 81 of the operation panel 8. The control unit 9 functions as an operation control unit 91, a measurement unit 92, and a correction unit 93 by executing a computer program stored in advance in the storage unit 10. The control part 9 is comprised from CPU (Central Processing Unit), for example.

  The storage unit 10 includes a semiconductor memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory). For example, the ROM stores various computer programs executed by the control unit 9. The RAM stores, for example, image data of an image formed on the paper S.

  The storage unit 10 of the present embodiment stores a reference time. The reference time is the time during which a reference sheet S such as A4 size plain paper comes into contact with the sensor slice 56a during conveyance. The reference time is, for example, the time when the detection signal is continuously output from the detection unit 56c during the initial operation described with reference to FIG. The reference time may be stored in advance in the storage unit 10.

  The operation control unit 91 controls the operations of the image forming unit 3, the fixing unit 4, and the registration roller 51. Specifically, the operation control unit 91 matches the timing at which the registration roller 51 conveys the paper S and the timing at which the image forming unit 3 and the fixing unit 4 form an image based on the detection signal of the detection unit 56c. In this manner, the operations of the image forming unit 3, the fixing unit 4, and the registration roller 51 are controlled. Further, the operation control unit 91 stops the operation of the image forming unit 3 and the fixing unit 4 when the sheet S passes through the image forming unit 3 and the fixing unit 4 based on the detection signal of the detection unit 56c. The operations of the image forming unit 3, the fixing unit 4, and the registration roller 51 are controlled so that the timing matches.

  The measurement unit 92 measures the time during which the detection signal is output from the detection unit 56c. Moreover, the measurement part 92 produces | generates detection time based on the measured time.

  The correction unit 93 compares the detection time with the reference time stored in the storage unit 10. The correction unit 93 corrects the timing at which the operation control unit 91 stops the image forming unit 3, the fixing unit 4, and the registration roller 51 when the detection time is shorter than the reference time. Specifically, the correction unit 93 performs correction by adding a correction time to the timing at which the operation control unit 91 stops. The correction time is stored in advance in the storage unit 10 based on the difference between the reference time and the detection time.

  The abrasion generated in the sensor section 56a described with reference to FIGS. 4 to 6 increases with the operation amount of the image forming apparatus 1, that is, the number of sheets S conveyed. However, the speed at which the wear of the sensor slice 56a increases varies depending on the use environment of the image forming apparatus 1 such as the surface roughness of the paper S, the installation environment of the image forming apparatus 1, the transport speed of the paper S, and the like. As a result, when using a correction value predicted from the operation amount and stored in advance, the actual wear amount and the correction value are different, and an error may occur in the formation position of the image formed on the paper S.

  As described with reference to FIGS. 1 to 7, in the present embodiment, the correction control unit 93 causes the operation control unit 91 to perform the image forming unit 3, the fixing unit 4, and the resist based on the reference time and the detection time. The timing for stopping the roller 51 is corrected. Accordingly, the error corresponding to the wear of the sensor segment 56a is corrected. As a result, in the image forming apparatus 1 of the present embodiment, the error due to wear of the sensor section 56a can be corrected more accurately, the timing at which the sheet S passes through the image forming unit 3 and the fixing unit 4, and the image forming unit 3, In addition, the timing at which the operation of the fixing unit 4 stops is matched, so that the image forming accuracy can be improved.

The control unit 9 of this embodiment further functions as a notification unit 94 by executing a computer program stored in advance in the storage unit 10. When the difference between the reference time and the detection time is larger than the threshold value, the notification unit 94 notifies the outside of the replacement time of the sensor intercept 56a. The notification unit 94 according to the present embodiment replaces the reference time with the length of the reference sheet S, and replaces the detection time with the length of the conveyed sheet S to determine the replacement timing of the sensor slice 56a. Specifically, the difference between the length of the reference sheet S and the length of the conveyed sheet S is calculated using the following equation (1). When the difference between the length of the reference sheet S and the length of the conveyed sheet S is larger than the threshold value, the notification unit 94 notifies the replacement time to the outside. The threshold is, for example, 5.0 mm when an image is formed on A4 size paper S. As a result, in the image forming apparatus 1 of the present embodiment, it is possible to notify the outside when the sensor section 56a is to be replaced at an optimal time.
Reference length x (reference time-detection time) / reference time (1)

  For example, the notification unit 94 controls the display unit 81 of the operation panel 8 so as to display a message for notifying the replacement timing of the sensor slice 56a. As a result, the user of the image forming apparatus 1 can be notified of the replacement time of the sensor slice 56a.

  The function of the correction unit 93 of this embodiment may be stopped by the user. Specifically, when there is a difference between the reference time and the detection time, the control unit 9 controls the display unit 81 so as to display a selection message such as “Do you want to disable the correction function?” . When it is input via the input unit 82 that the user has selected invalidity, the control unit 9 controls the correction unit 93 so that correction due to wear of the sensor segment 56a is not performed. As a result, in the image forming apparatus 1 of the present embodiment, for example, even when an image is formed on the sheet S having a length slightly smaller than the A4 size, the correction unit 93 does not malfunction and image formation is performed. Accuracy can be maintained.

  Further, the correction unit 93 of the present embodiment corrects the timing at which the operation control unit 91 stops the image forming unit 3, the fixing unit 4, and the registration roller 51 only when an image is formed on the paper S that is plain paper. May be. As a result, for example, it is possible to avoid erroneous correction for a flexible sheet S such as thin paper. The type of paper S is detected by, for example, the detection unit and determined by the control unit 9. The detection unit is, for example, an optical sensor such as a media sensor provided in the storage unit 6. The detection unit outputs a detection signal including the reflectance of reflected light and the wavelength. The control unit 9 further functions as a determination unit by executing a computer program stored in advance in the storage unit 10. The determination unit determines the type of the paper S based on the detection signal.

  The correction unit 93 may correct the timing at which the operation control unit 91 stops the image forming unit 3, the fixing unit 4, and the registration roller 51 regardless of the type of the paper S. The correction unit 93 acquires a correction time corresponding to the type of the paper S stored in the storage unit 10 in advance based on the type of the paper S determined by the determination unit. Therefore, the correction unit 93 corrects the timing at which the operation control unit 91 stops the image forming unit 3, the fixing unit 4, and the registration roller 51 with the correction time corresponding to the type of the paper S. As a result, the image forming apparatus 1 can improve the image forming accuracy regardless of the type of the paper S.

  Subsequently, correction control of the control unit 9 according to the present embodiment will be described with reference to FIGS. 7 and 8. FIG. 8 is a flowchart showing the correction control of the control unit 9. In the present embodiment, the reference time is stored in the storage unit 10 prior to the correction control.

  As shown in FIG. 8, in step S10, a detection signal is input from the detection unit 56c to the measurement unit 92. When a detection signal is input in step S10, the measurement unit 92 generates a detection time in step S20. When the detection time is generated in step S20, the correction unit 93 compares the detection time with the reference time in step S30. In step S30, when the detection time is equal to the reference time (No in step S30), in step S40, the operation control unit 91 presets the operations of the image forming unit 3, the fixing unit 4, and the registration roller 51. Then, control is performed at the normal timing, and the correction control is terminated.

  In step S30, when the detection time is shorter than the reference time (Yes in step S30), in step S50, the notification unit 94 compares an error, which is a difference between the detection time and the reference time, with a threshold value. In step S50, when the error is less than the threshold value (No in step S50), in step S60, the correction unit 93 performs normal operations set in advance for the operations of the image forming unit 3, the fixing unit 4, and the registration roller 51. A correction time corresponding to the error is added to the timing. In step S60, the operation control unit 91 controls the operations of the image forming unit 3, the fixing unit 4, and the registration roller 51 at the timing when the correction time is added, and ends the correction control.

  If the error is greater than or equal to the threshold value in step S50 (Yes in step S50), in step S70, the notification unit 94 notifies the replacement time to the outside. Further, when the replacement time is notified in step S70, the process proceeds to step S60. According to the correction control of the present embodiment, it is possible to more accurately correct an error due to wear of the sensor segment 56a, thereby improving the image forming accuracy. In addition, the user can be notified of the replacement time of the sensor slice 56a.

  The image forming apparatus 1 according to the embodiment of the present invention has been described above with reference to FIGS. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof.

  For example, in the embodiment of the present invention, the notification unit 94 controls the display unit 81 of the operation panel 8 to display a message notifying the replacement time, but the present invention is not limited to this. For example, the image forming apparatus 1 may further include a communication unit connected to the Internet, and the notification unit 94 may control the communication unit so as to notify the service center of the image forming apparatus 1 of the replacement time.

  In order to facilitate understanding, the drawings schematically show each component mainly, and the thickness, length, etc. of each component shown in the drawings are different from the actual for convenience of drawing. . In addition, the material, shape, dimensions, and the like of each component shown in the above embodiment are merely examples, and are not particularly limited, and various changes can be made without departing from the effects of the present invention. is there.

  The present invention relates to an image forming apparatus, and is useful for an image forming apparatus including a conveyance unit having a registration roller that temporarily stops conveyance of a recording medium and corrects the posture of the recording medium.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Image forming part 5 Conveying part 9 Control part 51 Registration roller 56 Registration sensor 56a Sensor section 56c Detection part 91 Operation control part 92 Measurement part 93 Correction part S Paper

Claims (7)

An image forming unit that forms an image on a recording medium conveyed along a conveyance path;
A transport unit that transports the recording medium along the transport path;
A sensor for detecting the recording medium conveyed by the conveying unit;
A control unit that controls the image forming unit and the transport unit;
The sensor is
A sensor piece that is tilted from an initial position in contact with the front end of the recording medium, and is separated from a rear end of the recording medium to return to the initial position;
A detection unit that outputs a detection signal indicating that the sensor intercept is tilted,
The controller is
An operation control unit that controls operations of the image forming unit and the transport unit based on the detection signal;
A measurement unit that measures the time that the detection signal is continuously output and generates a detection time;
An image forming apparatus comprising: a correction unit configured to correct timing for controlling the operation of the image forming unit and the transport unit by the operation control unit based on a difference between the detection time and the reference time.   The image forming apparatus according to claim 1, wherein the correction unit adds a correction time to the timing based on a difference between the detection time and the reference time. The control unit further includes a notification unit,
The image forming apparatus according to claim 1, wherein the notification unit notifies the wear of the sensor segment to the outside when a difference between the detection time and the reference time is greater than a threshold value.   The image forming apparatus according to claim 1, wherein the correction unit can be stopped by a user. The recording medium is A4 size plain paper,
The image forming apparatus according to claim 1, wherein the correction unit corrects the timing when an image is formed on the plain paper. A storage unit;
The image forming apparatus according to claim 1, wherein the storage unit stores the reference time measured during an initial operation of the sensor slice. The transport unit includes a registration roller that transports the recording medium to the image forming unit,
The image forming apparatus according to claim 1, wherein the sensor is located upstream of the registration roller in the transport path.

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