Conveying device and image forming apparatus

Abstract

To provide a conveying device capable of accurately detecting and correcting various types of sheets without performing a plurality of times of detections and corrections nor previously executing adjustment as a reference.SOLUTION: A conveying device 45 includes: a first holding roller 18; a second holding roller 17 consisting of a pair of rollers contactable to and separable from each other arranged on an upstream side of the first holding roller 18; positional deviation correction means 33 for correcting positional deviation in a width direction of a recording medium S; end position detection means 22, 23, 24 for detecting an end position of the recording medium S in the width direction; and adjustment means 36 for performing output adjustment of the end position detection means 22, 23, 24. When adjusting the end position detection means 22, 23, 24, conveyance of the recording medium S is stopped when a tip end part of the recording medium S reaches the end position detection means 24, and the recording medium S is moved to a position for covering the end position detection means 24 by the positional deviation correction means 33, and the adjustment means 36 performs output adjustment of the end position detection means 24 so that the end position detection means 24 detects the recording medium S.SELECTED DRAWING: Figure 21

Description

[Technical field]

[0001] The present invention relates to a conveying device and an image forming apparatus. [Background technology]

[0002] In image forming devices such as copiers and printers, there is known a technique for correcting the skew of a sheet conveyed along a conveying path, and for detecting a deviation in the width direction (called main scanning registration) perpendicular to the conveying direction of the sheet, and correcting the conveying position of the sheet to a reference position. However, this technique has a problem in that when sheets with different reflectances due to different colors, etc., are conveyed, there is a risk that the sheet posture cannot be accurately corrected.

[0003] In view of this, a technique has been proposed in which at least one of the light emission time of a detection means that optically detects the position of a sheet according to the reflectance of the sheet, the time interval for performing a correction operation, the light emission intensity of the detection means, and the conveying speed of a pair of rollers that sandwich and convey the sheet in the conveying path is set to perform a correction operation (see, for example, "Patent Document 1"). In this technique, the edge of the sheet is detected by the detection means to calculate the amount of deviation of the sheet, and the detection means detects the edge of the sheet by receiving light that is irradiated from a light source and reflected by the sheet.

[0004] Since the above-mentioned detection means have a variation in accuracy for each part, the amount of light emitted and the output level of the detection means are adjusted using a reference white sheet so that the sheet can be detected. In addition, since the sheets actually used are diverse in color and transparency, it was necessary to make a certain amount of adjustment from the adjusted value before using them. "Patent Document 1" discloses a technology in which sheet detection and position correction are performed once, and the control settings of the detection means are changed according to the reflectance of the sheet. Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned technology is based on the premise that sheet detection and position correction are performed two or more times, and has a problem that it cannot be performed in a device that performs detection and position correction only once due to structural constraints. In addition, sheet reflectance detection using a detection means is based on the premise that the sheet can be detected in the first detection using a reference setting, so reference setting is essential, and it cannot be applied to sheets that cannot be detected in the reference setting, and further, there is a problem that the sheet position cannot be corrected with high accuracy. Furthermore, since the position correction is performed using the first detection result, there is a problem that malfunctions and sheet transport jams occur. The present invention aims to solve the above-mentioned problems and provide a conveying device and an image forming apparatus that can correctly detect and correct a wide variety of sheets without performing detection and correction multiple times and without performing standard adjustments in advance. [Means for solving the problem]

[0006] The invention described in claim 1 comprises a first clamping roller consisting of a pair of rollers that clamp and transport a recording medium, a second clamping roller consisting of a pair of rollers that can be moved toward and away from each other and is arranged upstream of the first clamping roller in a transport path for the recording medium, a position shift correction means for correcting position shift in the width direction of the recording medium transported along the transport path, an end position detection means that is provided from the inside to the outside of the transport path in the width direction and detects an end position of the recording medium in the width direction, and an adjustment means for adjusting the output of the end position detection means, wherein when adjusting the end position detection means, the transport of the recording medium is stopped when the leading end of the recording medium reaches the end position detection means, the position shift correction means moves the recording medium towards the outside of the transport path until it covers the end position detection means, and the adjustment means adjusts the output of the end position detection means so that the end position detection means detects the recording medium. Effect of the Invention

[0007] According to the present invention, a wide variety of recording media can be correctly detected by the edge position detection means without performing detection and correction multiple times and without performing a reference adjustment in advance. This makes it possible to provide a conveying device that can accurately correct the positional deviation of the recording media with simple adjustment. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. [Diagram 2] 1 is a schematic configuration diagram of a transport device according to a first embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic plan view illustrating a conveying device and a skew correction operation according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view of a main part for explaining a drive mechanism of the transport device according to the first embodiment of the present invention. [Diagram 5] 5A to 5C are schematic diagrams illustrating a skew correction operation of the conveying device according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a block diagram of a control unit used in the transport device according to the first embodiment of the present invention. [Figure 7] 5 is a flowchart illustrating a first correction operation of the transport device according to the first embodiment of the present invention. [Figure 8] 6 is a flowchart illustrating a second correction operation of the transport device according to the first embodiment of the present invention. [Figure 9] FIG. 4 is a schematic plan view illustrating a first correction operation of the transport device according to the first embodiment of the present invention. [Figure 10] FIG. 4 is a schematic plan view illustrating a first correction operation of the transport device according to the first embodiment of the present invention. [Figure 11] FIG. 4 is a schematic plan view illustrating a first correction operation of the transport device according to the first embodiment of the present invention. [Figure 12] FIG. 4 is a schematic plan view illustrating a first correction operation of the transport device according to the first embodiment of the present invention. [Figure 13]FIG. 4 is a schematic plan view illustrating a second correction operation of the transport device according to the first embodiment of the present invention. [Figure 14] FIG. 4 is a schematic plan view illustrating a second correction operation of the transport device according to the first embodiment of the present invention. [Figure 15] FIG. 2 is a schematic diagram illustrating an end position detection unit used in the first embodiment of the present invention. [Figure 16] 1A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a first embodiment of the present invention; FIG. [Figure 17] 1A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a first embodiment of the present invention; FIG. [Figure 18] 1A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a first embodiment of the present invention; FIG. [Figure 19] 1A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a first embodiment of the present invention; FIG. [Figure 20] 1A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a first embodiment of the present invention; FIG. [Figure 21] 5 is a flowchart illustrating an adjustment operation of an end position detection unit in the transport device according to the first embodiment of the present invention. [Figure 22] FIG. 4 is a schematic diagram illustrating a light absorbing member used in a modified example of the first embodiment of the present invention. [Figure 23] 13A is a schematic plan view illustrating a detection operation and an adjustment operation of an end position detection means in a transport device according to a second embodiment of the present invention, and FIG. 13B is a schematic front view of the same. [Figure 24] 13A is a schematic plan view illustrating a detection operation and an adjustment operation of an end position detection means in a transport device according to a second embodiment of the present invention, and FIG. 13B is a schematic front view of the same. [Diagram 25]13A is a schematic plan view illustrating a detection operation and an adjustment operation of an end position detection means in a transport device according to a second embodiment of the present invention, and FIG. 13B is a schematic front view of the same. [Figure 26] 13A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a second embodiment of the present invention, and FIG. 13B is a schematic front view of the same. [Figure 27] 13A is a schematic plan view illustrating an adjustment operation of an end position detection means in a transport device according to a second embodiment of the present invention, and FIG. 13B is a schematic front view of the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 1 shows a copying machine as an image forming apparatus according to a first embodiment of the present invention. In the figure, the copying machine 1 includes an image reading unit 3 that optically reads image information from an original 2, an exposure unit 5 that irradiates the surface of a photosensitive drum 4 with exposure light L based on the image information read by the image reading unit 3, and an image creating unit 6 that includes the photosensitive drum 4 and forms a toner image on the surface of the photosensitive drum 4. The image reading unit 3 is provided with an original transport unit 7 that transports the original 2 that is set thereon. Below the photosensitive drum 4 is a transfer roller 8 which transfers the toner image formed on the peripheral surface of the photosensitive drum 4 onto a sheet S, and below the image creating unit 6 is a paper feeding unit 12 which has a number of paper feeding cassettes 9, 10, and 11 which store the sheet S, which is the recording medium. A fixing device 15 having a heating roller 13 with an internal heat source and a pressure roller 14 in pressure contact with the heating roller 13 is disposed downstream of the imaging unit 6 in the sheet conveying direction.

[0010] Between the paper feed section 12 and the imaging section 6, a plurality of conveying roller pairs 16 and conveying roller pairs 17 are arranged to convey the sheet S fed from the paper feed section 12. Each conveying roller pair 16 has a drive roller and a driven roller pressed against the drive roller, and conveys the sandwiched sheet S when the drive roller is rotationally driven by a driving means (not shown). The conveying roller pair 17 functioning as a second sandwiching roller also has a drive roller and a driven roller pressed against the drive roller, and conveys the sandwiched sheet S when the drive roller is rotationally driven by a driving means (not shown). The driven roller constituting the conveying roller 17 is moved by a contacting / separating means (not shown) and is selectively displaced to a pressing position where it is in pressure contact with the drive roller or a separated position where it is separated from the drive roller.

[0011] A registration roller pair 18 is disposed downstream of the conveying roller pair 17 in the sheet conveying direction to feed the sheet S conveyed by the conveying roller 17 toward between the photosensitive drum 4 and the transfer roller 8 at a predetermined timing. The registration roller pair 18, which functions as a first pinching roller, is configured to be able to perform skew correction and main scanning registration correction of the sheet S. A detailed configuration of the registration roller pair 18 will be described later. An operation panel 37 equipped with a display device, which is operated by a user of the copier 1, is disposed on the upper surface of the main body of the copier 1, located above the image reading unit 3.

[0012] Here, the image forming operation of the copying machine 1 under normal circumstances will be described. 1 from the document tray by the transport rollers of document transport unit 7, and image information is optically read as the document passes over an image reading sensor provided in image reading unit 3. The optical image information read by image reading unit 3 is converted into an electrical signal and then sent to exposure unit 5. Exposure light L based on the image information converted into this electrical signal is emitted from exposure unit 5 toward the circumferential surface of photosensitive drum 4. 1, a toner image is formed on the circumferential surface of the photosensitive drum 4 through an image forming process including a well-known charging step, an exposure step, and a developing step. The formed toner image is transferred onto a sheet S fed from a pair of registration rollers 18 in a transfer nip portion where the photosensitive drum 4 and a transfer roller 8 come into contact with each other.

[0013] 1 and 2, one of the paper feed cassettes 9, 10, and 11 in the paper feed unit 12 is automatically or manually selected. In this example, it is assumed that the paper feed cassette 9 is selected. The topmost sheet S in the selected paper feed cassette 9 is separated and fed by the paper feed roller 19, and is conveyed toward a curved conveying path in which the conveying roller pairs 16 are arranged. Thereafter, the sheet S passes through a junction 20 where the sheet transport paths from the curved transport path and the sheet transport paths from the two paper feed cassettes 10 and 11 arranged outside the main body of the apparatus join, and is then sent to a registration roller pair 18 via a straight transport path in which a transport roller pair 17 and a registration roller pair 18 are arranged. Then, after skew correction and main scanning registration correction are performed by the registration roller pair 18, the registration roller pair 18 is rotated at a predetermined timing that matches the toner image formed on the photosensitive drum 4, and the sheet S is fed toward the transfer nip portion.

[0014] When sheet S is fed toward the transfer nip portion, the transfer roller 8 and the photosensitive drum 4 each rotate in the direction of transporting the sheet S, and the transfer roller 8 and the photosensitive drum 4 function as downstream transport rollers arranged downstream in the sheet transport direction relative to the pair of registration rollers 18. The sheet S onto which the toner image has been transferred in the transfer nip is sent to the fixing device 15 via a sheet transport path. The sheet S sent to the fixing device 15 is fed between a heating roller 13 and a pressure roller 14, where the toner image is fixed by heat and pressure. The sheet S with the fixed image is discharged from the device body to the outside by a pair of discharge rollers 21, and is discharged and stacked on a discharge tray (not shown). With these operations, a series of image forming operations is completed.

[0015] As described above, a linear transport path formed in a substantially straight line along the transport direction of the sheet S is provided as a transport path from the junction 20 to the transfer nip. This linear transport path is formed by a pair of linear transport guide plates (not shown) provided to sandwich the front and back surfaces of the transported sheet S, and as shown in Fig. 3, a transport roller pair 17, a first CIS 22, a second CIS 23, a registration roller pair 18, and a third CIS 24 are arranged in this order from the upstream side in the sheet transport direction. Each of the CISs 22, 23, and 24 is a contact image sensor consisting of a plurality of photosensors arranged in parallel in the sheet width direction, and optically detects a side end portion (edge ​​portion) Sa of the sheet S passing each photosensor. With this configuration, each of the CISs 22, 23, and 24 functions as an end position detection unit.

[0016] Next, a specific configuration of the pair of registration rollers 18 will be described with reference to FIG. The registration roller pair 18 is a roller pair having a roller portion divided into a plurality of pieces in the sheet width direction, and includes a drive roller 18a that is rotationally driven by the first drive motor 25, and a driven roller 18b that rotates following the rotation of the drive roller 18a. Note that, although a roller pair having roller portions divided into a plurality of pieces in the sheet width direction is used as the registration roller pair 18 in this embodiment, a roller pair having roller portions that extend without being divided in the sheet width direction may also be used. The pair of registration rollers 18 is configured to be rotatable in an inclined direction relative to the conveying direction of the sheet S (rotating in the direction of the double-headed arrow W shown in Figure 3, which is a direction parallel to the sheet conveying surface) and to be movable in the sheet width direction (the direction of the double-headed arrow R shown in Figure 3).

[0017] The first drive motor 25 is fixed to a frame (not shown) of the device body, and a drive gear 26 is provided on the output shaft of the first drive motor 25. The rollers 18a, 18b are supported by a holding member 30 supported by a frame 27 so that the support shafts of the rollers 18a, 18b are rotatably supported by the upright portion 27a of the frame 27. The frame side rotation shaft 28 is provided with a gear portion 28a having a sufficient length in the axial direction, and the drive gear 26 is engaged with the gear portion 28a. The support shaft of the drive roller 18a and the frame side rotation shaft 28 are connected by a coupling 29. As a result, when the frame side rotation shaft 28 rotates in the direction of the arrow Q in FIG. 4 by the driving force of the first drive motor 25, the rotation force is transmitted to the support shaft of the drive roller 18a via the coupling 29, and the drive roller 18a rotates, and the driven roller 18b rotates in response to the rotation. The coupling 29 is a shaft coupling such as a constant velocity joint or a universal joint, and is capable of transmitting the rotational driving force without causing a change in the rotational speed of the registration roller pair 18 even when the registration roller pair 18 rotates together with the holding member 30 as described below, changing the shaft angle between the support shaft of the drive roller 18a and the frame side rotation shaft 28.

[0018] Each of the rollers 18a, 18b is supported by a rectangular holding member 30 so as to be rotatable and axially movable. Specifically, each of the rollers 18a, 18b is supported rotatably and movably via a bearing member (not shown) whose both ends of the support shaft are fixed to the holding member 30. In addition, an arc-shaped gear portion 30b that is integrally formed and protrudes from the support portion 30a is attached to one end side of the holding member 30 in the sheet width direction. A sufficient gap is provided between the support portion 30a and the gear portion 30b in the sheet width direction, so that the support shaft of each of the rollers 18a, 18b does not interfere with the gear portion 30b even if each of the rollers 18a, 18b slides in the axial direction.

[0019] The holding member 30 is supported rotatably about a shaft portion 27b with respect to a frame 27 that functions as a part of the frame of the device main body. A second drive motor 31 that can rotate forward and backward is installed on one end side of the frame 27 in the sheet width direction. A gear provided on a motor shaft 31a of the second drive motor 31 is connected to a gear portion 30b With this configuration, when the second drive motor 31 is driven to rotate in the forward and reverse directions, the pair of registration rollers 18 together with the holding member 30 rotates about the shaft portion 27b in the direction of the arrow W shown in FIGS. The second drive motor 31 rotatably displaces the registration roller pair 18 and the holding member 30 in a tilted direction with respect to the conveying direction of the sheet S based on the detection results of each of the above-mentioned CISs 22, 23, and 24. The second drive motor 31 is provided with a well-known encoder and is configured to be able to detect the amount and direction of displacement of the registration roller pair 18 in the tilted direction with respect to the reference position. This makes it possible to correct the skew of the registration roller pair 18 based on the detection results of each of the CISs 22, 23, and 24. With this configuration, the second drive motor 31 functions as a skew correction means. In this embodiment, the pair of registration rollers 18 is configured to rotate about approximately the center position in the sheet width direction, but may be configured to rotate about a different position.

[0020] A rack gear portion 32 is provided on the other end side in the sheet width direction of the frame-side rotating shaft 28, which is rotatably supported by the frame 27. The rack gear portion 32 is supported by the device body so as to be slidable together with the frame-side rotating shaft 28 in the sheet width direction shown by the arrow R in Fig. 4 in a non-rotating state along a guide rail (not shown) formed on the device body. A third drive motor 33 is also installed on the device body, the motor shaft 33a of which has a pinion gear that meshes with the rack gear portion 32. A connecting member 34 is provided between the support column on the other end side of the holding member 30 in the sheet width direction and the coupling 29. The connecting member 34 rotatably connects the rollers 18a, 18b so that the rollers 18a, 18b move in the sheet width direction in conjunction with each other, and is clamped by a stop ring 35 installed in a groove formed in each of the support shafts of the rollers 18a, 18b. When the driving roller 18a moves in the sheet width direction due to the action of the connecting member 34, the driven roller 18b also moves in the sheet width direction by the same distance in conjunction with this.

[0021] With the above-mentioned configuration, the pair of registration rollers 18 moves in the sheet width direction indicated by the arrow R in Figures 3 and 4 by the rotational drive of the third drive motor 33 in the forward and reverse directions. Therefore, the third drive motor 33 moves the frame side rotating shaft 28 and the pair of registration rollers 18 in the sheet width direction based on the detection results of each of the CISs 22, 23, and 24 described above. A known encoder is provided on the motor shaft 33a of the third drive motor 33, and is configured to be able to detect the amount and direction of displacement of the registration roller pair 18 in the sheet width direction relative to the reference position. This makes it possible to perform main scanning registration correction of the registration roller pair 18 based on the detection results of each CIS 22, 23, and 24. With this configuration, the third drive motor 33 teeth It functions as a main scanning registration correcting means which is a position deviation correcting means. The above-mentioned components such as the third drive motor 33, rack gear portion 32, frame side rotating shaft 28, coupling 29, connecting member 34, and holding member 30 constitute a moving mechanism that moves the registration roller pair 18 in the sheet width direction.

[0022] The registration roller pair 18 conveys the sheet S while sandwiching it, and corrects the amount of misalignment of the sheet S by rotating together with the holding member 30 based on the detection results of two of the CISs 22, 23, and 24. That is, the registration roller pair 18 functions as a means for performing skew correction (oblique feed correction) of the sheet S by displacing the sheet S conveyed in the conveying path in a direction inclined with respect to the conveying direction. The registration roller pair 18 conveys the sheet S while sandwiching it, and corrects the amount of misalignment of the sheet S by moving in the sheet width direction based on the detection results of two of the CISs 22, 23, and 24. That is, the registration roller pair 18 also functions as a means for correcting the misalignment of the sheet S, that is, performing main scanning registration correction, by displacing the sheet S conveyed in the conveying path in the sheet width direction.

[0023] In this embodiment, the pair of registration rollers 18 rotates while sandwiching the sheet S, and conveys the sheet S toward the transfer nip after performing skew correction and main scanning registration correction. Here, the first drive motor 25 that rotates and drives the pair of registration rollers 18 is a variable rotation speed motor, and is capable of changing the conveying speed of the sheet S. Then, when a photosensor (not shown) detects that the sheet S is sandwiched between the pair of registration rollers 18, the pair of registration rollers 18 performs the desired skew correction and main scanning registration correction, and further, the sheet conveying speed of the pair of registration rollers 18 is changed based on the detection timing of the photosensor. That is, the sheet conveying speed of the pair of registration rollers 18 is changed so that the timing at which the pair of registration rollers 18 feeds the sheet S to the transfer nip coincides with the timing at which the toner image formed on the photosensitive drum 4 reaches the transfer nip. As a result, an image can be formed at a desired position on the sheet S while the pair of registration rollers 18 performs skew correction and main scanning registration correction on the sheet S. The conveying speed of the registration roller pair 18 is changed so that a linear speed difference does not occur between the registration roller pair 18 and the photosensitive drum 4 immediately after the leading edge of the sheet S reaches the transfer nip portion, causing distortion of the image transferred onto the sheet S.

[0024] 3, the above-mentioned first CIS 22 and second CIS 23 are disposed between the conveying roller pair 17 and the registration roller pair 18. The CISs 22 and 23 are disposed such that the first CIS 22 is located upstream in the sheet conveying direction. In addition, a third CIS 24 is disposed between the registration roller pair 18 and the transfer roller 8. In this embodiment, the amount of positional deviation in the inclination direction of the first sheet S transported by the first CIS 22 and the second CIS 23 or the second CIS 23 and the third CIS 24, i.e., the skew amount, is detected. Then, skew correction is performed based on this detection result. At the same time, the amount of positional deviation in the sheet width direction of the first sheet S transported by the first CIS 22 and the second CIS 23, i.e., the main scanning registration amount, is detected. Then, main scanning registration correction is performed based on this detection result.

[0025] Here, a specific example of skew correction will be described. First, as shown in Fig. 3, the first CIS 22 and the second CIS 23 or the second CIS and the third CIS 24 detect a state in which the sheet S is skewed by an angle β in the forward direction of the skew correction direction W (counterclockwise direction in Fig. 3) with respect to the normal position without skew, as shown by the dashed line. Next, the control means 36 described later determines the skew amount β as the skew correction amount, and rotates the registration roller pair 18 by the angle β in the opposite direction to the skew correction direction W (clockwise direction in Fig. 3) while the sheet S is sandwiched between the registration roller pair 18.

[0026] In detail, as shown in FIG. 5, the skew amount β, which is the amount of misalignment in the inclination direction of the sheet S, is detected based on the value (M2-M1) / H obtained by dividing the difference M2-M1 between the amount of misalignment M1 in the sheet width direction of the sheet S detected by the first CIS 22 (or the second CIS 23) and the amount of misalignment M2 in the sheet width direction of the sheet S detected by the second CIS 23 (or the third CIS 24) by the distance H between the first CIS 22 (or the second CIS 23) and the second CIS 23 (or the third CIS 24). Then, the correction angle β for correction is calculated as tan β using the calculated value (M2-M1) / H, and the pair of registration rollers 18 is rotated in the opposite direction while the sheet S is sandwiched between the pair of registration rollers 18 so as to cancel the angle β. The above-mentioned positional deviation amounts M1 and M2 in the sheet width direction are both deviation amounts from the normal position of the sheet S indicated by the two-dot chain line in FIG.

[0027] 6 calculates the amount of skew β based on the detection results from the first CIS 22 and the second CIS 23, or the second CIS 23 and the third CIS 24, and calculates a count number p1 in the encoder of the second drive motor 31 based on the amount of skew β. Then, the count number p1 is stored as a target transport encoder count number p1 for the second drive motor 31, and the second drive motor driver 39 is controlled by the second drive motor control unit 38 while performing position detection based on this target transport encoder count number p1, and the second drive motor 31 is driven.

[0028] Next, a specific example of main scanning registration correction will be described. First, as shown in Fig. 3, a state in which the sheet S is shifted by a distance α toward one end in the sheet width direction, which is downward in Fig. 3, from the normal position is detected by the first CIS 22 and the second CIS 23 or the second CIS and the third CIS 24. Next, the control means 36 determines the main scanning registration amount α as the main scanning registration correction amount, and displaces the registration roller pair 18 by the distance α toward the other end in the sheet width direction, which is upward in Fig. 3, while the sheet S is sandwiched between the registration roller pair 18.

[0029] Specifically, a main scanning resist amount α, which is the amount of misalignment of the sheet S in the width direction, is detected based on the average value (M1+M2) / 2 of the above-mentioned amounts of misalignment M1 and M2. Then, the obtained value (M1+M2) / 2 is set as the main scanning registration amount α, and the registration roller pair 18 is displaced while the sheet S is sandwiched between the registration roller pair 18 so as to cancel out this value. The control means 36 calculates the main scanning registration amount α based on the detection results by the first CIS 22 and the second CIS 23, or the second CIS 23 and the third CIS 24, and calculates a count number p2 of the encoder of the third drive motor 33 based on the main scanning registration amount α. Then, the count number p2 is stored as a target transport encoder count number p2 of the third drive motor 33, and the third drive motor control unit 40 controls the third drive motor driver 41 while performing position detection based on this target transport encoder count number p2, and the third drive motor 33 is driven. In addition, the calculation of the target transport encoder count numbers p1 and p2 is performed by finding in advance the correction amount (transport amount) per count (one pulse) by calculation from the design value or the like, and storing the result in the calculation unit.

[0030] As described above, in this embodiment, based on the detection results of the multiple CISs 22, 23, and 24, the pair of registration rollers 18 rotate in an inclined direction to perform skew correction of the sheet S without stopping the conveyance of the sheet S, and the pair of registration rollers 18 displaces in the sheet width direction to perform main scanning registration correction of the sheet S. This can significantly improve the productivity of the device compared to a case where the conveyance of the sheet S is stopped and skew correction and main scanning registration correction are performed separately. In addition, when performing skew correction and main scanning registration correction, there is no linear speed difference between the roller portions provided in the pair of registration rollers 18 in the sheet width direction, so that bending and slipping of the sheet S are prevented even when thin paper or a sheet S with a low surface friction coefficient is passed through.

[0031] In this embodiment, the CISs 22, 23, and 24 provided in the conveying path are used to perform the skew correction and main scanning registration correction of the sheet S by the registration roller pair 18 in two stages. That is, while the pair of registration rollers 18 is holding and transporting the sheet S, the CISs 22 and 23 detect the amount of skew and the amount of main scanning registration of the sheet S, and based on the detection results, the skew of the sheet S is corrected, and almost simultaneously, the main scanning registration of the sheet S is corrected. These correction operations are called the first correction operations. Furthermore, after the first correction is performed, the second CIS 23 and the third CIS 24 detect the skew amount and main scanning registration amount of the sheet S while the registration roller pair 18 is holding and transporting the sheet S, and the skew correction of the sheet S is performed based on the detection result, and almost simultaneously, the main scanning registration correction of the sheet S is performed. These correction operations are called second correction operations. In the second correction operation, the correction operation for correcting the inclination direction and the posture in the sheet width direction of the sheet S based on the detection results of either the first CIS 22 or the second CIS 23 and the third CIS 24 is repeated to the extent possible until just before the leading edge of the sheet S reaches the transfer nip portion, which will be described later.

[0032] In this embodiment, before the sheet S is conveyed to the registration roller pair 18, based on the detection result of the first CIS 22 or the second CIS 23, the registration roller pair 18 is rotated by the second drive motor 31 from the rotation reference position (a position corresponding to the normal position of the sheet S without positional deviation in the skew direction) which is an initial position, so as to face the end of the sheet S shifted in the skew direction to correspond to the skew amount of the sheet S. Furthermore, in parallel with this rotation operation, the registration roller pair 18 is moved in the sheet width direction from the movement reference position (a position corresponding to the normal position of the sheet S without positional deviation in the sheet width direction) by the third drive motor 33 to correspond to the main scanning registration amount of the sheet S. Thereafter, the pair of registration rollers 18 holding the sheet S are rotated by the second drive motor 31 so as to return to the rotation reference position so as to correct the skew amount, and are displaced by the third drive motor 33 so as to return to the movement reference position so as to correct the main scanning registration amount, which is the positional deviation in the sheet width direction. This is the first correction operation described above.

[0033] After the first correction operation, a second correction operation is performed. The posture of the sheet S (the amount of skew and the amount of main scanning registration) after the amount of skew and the amount of main scanning registration of the sheet S are respectively corrected by the pair of registration rollers 18 is detected by the first CIS 22 (or the second CIS 23) and the third CIS 24 arranged to sandwich the pair of registration rollers 18. Then, the amount of skew and the amount of main scanning registration of the sheet S are further corrected based on the detection result. This is the second correction operation. During the second correction operation, the registration roller pair 18 further rotates from the above-mentioned rotation reference position while sandwiching the sheet S so as to further correct the skew amount of the sheet S based on the detection results of the first CIS 22 (or the second CIS 23) and the third CIS 24. At the same time, the registration roller pair 18 further displaces in the sheet width direction from the above-mentioned movement reference position while sandwiching the sheet S so as to further correct the main scanning registration amount of the sheet S.

[0034] As described above, in this embodiment, skew correction and main scanning registration correction are performed as a first correction operation while the sheet S is nipped and conveyed by the registration roller pair 18 based on the detection result before the sheet S is sandwiched between the registration roller pair 18. Then, thereafter, skew correction and main scanning registration correction are performed again as a second correction operation while the sheet S is nipped and conveyed by the registration roller pair 18 based on the detection results of the first CIS 22 (or the second CIS 23) and the third CIS 24. This is because there is a risk of slight skew or main scanning registration misalignment occurring due to the impact when the sheet S enters the nip portion of the registration roller pair 18, and there is also a risk of slight skew or main scanning registration misalignment occurring when eccentricity or assembly defects occur in the roller portion of the registration roller pair 18. In this embodiment, the second correction operation is performed after the first correction operation, so that the occurrence of the above-mentioned problems is prevented and more highly accurate skew correction and main scanning registration correction can be performed.

[0035] In this embodiment, when the first CIS 22 (or the second CIS 23) and the third CIS 24 are made to function in performing the second correction operation, the skew amount and main scanning registration amount of the sheet S are corrected by feedback control based on the detection results of the first CIS 22 (or the second CIS 23) and the third CIS 24, which are detected almost continuously. That is, in the second correction operation, the position information of the sheet S is successively detected by each of the two CISs, the skew amount and main scanning registration amount of the sheet S are calculated based on each position information and fed back to the control means 36, the skew correction amount and main scanning registration correction amount of the sheet S are successively corrected, and the drive of each motor 31, 33 is controlled based on each correction amount. This type of correction operation is repeated until just before the leading edge of the sheet S reaches the transfer nip portion, so that positional deviations and correction errors of the sheet S that occur during the second correction operation can be corrected responsively, and moreover, highly accurate skew correction and main scanning resist correction can be performed.

[0036] 6 shows a block diagram of the control means 36 that controls various operations of the copier 1. The control means 36, which is made up of a known microcomputer, has a recognition unit 42, a second drive motor control unit 38, a third drive motor control unit 40, etc. The control means 36 also has a function of adjusting the output of each of the CISs 22, 23, and 24, and in this case functions as an adjustment unit. The recognition unit 42 has a function of counting the main scanning resist amount and skew amount of the sheet S from the information received from each of the CISs 22, 23, and 24, and a function of recognizing the reflectance of the sheet S based on the detection results of each of the CISs 22, 23, and 24, as described below. The second drive motor control unit 38 determines the rotation direction and the amount of rotation of the second drive motor 31 based on the skew amount obtained from the recognition unit 42. The third drive motor control unit 40 determines the rotation direction and the amount of rotation of the third drive motor 33 based on the main scanning registration amount obtained from the recognition unit 42. The drive motor drivers 39, 41 receive signals from the drive motor control units 38, 40, respectively, and drive the drive motors 31, 33, respectively. The drive motor encoders 43, 44 detect the amount of rotation of the drive motors 31, 33, respectively.

[0037] Of the above-mentioned components, the conveying device 45 shown in Figures 2, 3, and 4 is composed of the second clamping roller 17, the pair of registration rollers 18 having the drive roller 18a and the driven roller 18b, each CIS 22, 23, 24, the first drive motor 25, the drive gear 26, the frame 27, the frame side rotating shaft 28, the coupling 29, the holding member 30, etc. The conveying device 45 further has a second drive motor 31, a rack gear unit 32, a third drive motor 33, a connecting member 34, a retaining ring 35, a control means 36 having a second drive motor control unit 38, a third drive motor control unit 40, and a recognition unit 42. The transport device 45 further includes a second drive motor driver 39, a third drive motor driver 41, a second drive motor encoder 43, a third drive motor encoder 44, and the like.

[0038] FIG. 7 is a flowchart illustrating the first correction operation in the transport device 45. First, each CIS 22, 23 detects the sheet S (ST01), and the skew amount and main scanning registration amount of the sheet S are calculated (ST02). Next, based on the detection results, the skew correction amount and main scanning registration correction amount are calculated (ST03), and the correction amount in the first correction operation is determined. Next, the encoder counts are calculated by the drive motor encoders 43 and 44 based on the correction amounts (ST04), and the drive motor drivers 39 and 41 drive the drive motors 31 and 33 in accordance with the calculated encoder counts, causing the registration roller pair 18 to rotate and move in the sheet width direction to perform a pick-up operation (ST05). At this time, the position information of the registration roller pair 18 is sequentially fed back by the drive motor encoders 43 and 44, and the registration roller pair 18 moves by a determined movement amount (ST06). Thereafter, after the pair of registration rollers 18 has sandwiched the sheet S (ST07), the contact / separation means (not shown) is actuated to cause the driven roller of the pair of conveying rollers 17 to assume the separated position, and the pair of registration rollers 18 is rotated to return to the reference position by the drive of each of the drive motors 31 and 33, and displaced in the sheet width direction, thereby performing a first correction operation (ST08). At this time, the position information of the pair of registration rollers 18 is sequentially fed back by each of the drive motor encoders 43 and 44, and the pair of registration rollers 18 moves by a determined movement amount (ST09). Then, when the pair of registration rollers 18 assumes a predetermined correction position, the first correction operation is completed (ST10).

[0039] FIG. 8 is a flowchart illustrating the second correction operation in the transport device 45. First, each CIS 23, 24 detects the sheet S (ST11), and the skew amount and main scanning registration amount of the sheet S are calculated (ST12). Next, the skew correction amount and main scanning registration correction amount are calculated based on these detection results (ST13), and the encoder count number is calculated (ST14). Then, the drive motors 31, 33 are driven by the drive motor drivers 39, 41 according to the calculated encoder count numbers, and a second correction operation is performed (ST15). At this time, the position information of the sheet S is successively detected by the CISs 23, 24, and the skew amount and main scanning registration amount are calculated based on this position information and fed back. Then, the skew amount and main scanning registration amount of the sheet S are successively corrected, and the registration roller pair 18 moves by a determined movement amount (ST16). Then, when the registration roller pair 18 occupies a predetermined correction position, the second correction operation is completed (ST17). Thereafter, the sheet S is sent to the transfer nip portion, and a contact / separation means (not shown) is activated so that the driven roller of the conveying roller pair 17 assumes a pressure contact position, and the sheet S is conveyed toward the fixing device 15 by the conveying force of the photosensitive drum 4 and the transfer roller 8 and the conveying force of the conveying roller pair 17.

[0040] Next, the operation of the transport device 45 will be described with reference to FIGS. 9, the sheet S fed from the paper feed unit 12 is nipped and conveyed by the conveying roller pair 17 toward the registration roller pair 18. At this time, the registration roller pair 18 is in the initial state, and is located at the rotation reference position and the movement reference position described above. Then, when the sheet S passes through the first CIS 22 and reaches the second CIS 23, the main scanning registration amount α of the sheet S and the skew amount β are detected by each of the CISs 22 and 23. Thereafter, as shown in FIG. 10, the pair of registration rollers 18, together with the holding member 30, are rotated by an angle β around the shaft portion 27b in the same inclination direction in accordance with the detected skew amount β, and are further displaced by a distance α in the same direction, that is, in the direction of arrow R1, in accordance with the detected main scanning registration amount α. Then, as shown in FIG. 11, just before the leading edge of the sheet S reaches the pair of registration rollers 18, the pair of registration rollers 18 starts to rotate, and when the sheet S is sandwiched and transported between the pair of registration rollers 18, a contact / separation means (not shown) is activated to displace the driven roller of the pair of transport rollers 17 to the separated position.

[0041] Thereafter, as shown in FIG. 12, the pair of registration rollers 18 rotates around the shaft portion 27b to return to the rotation reference position while clamping and transporting the sheet S to offset the skew amount β, and displaces in the direction of arrow R2 to return to the movement reference position to offset the main scanning registration amount α. 13, when the sheet S conveyed after the correction operation reaches the third CIS 24, the main scanning registration amount α and the skew amount β of the sheet S are detected substantially continuously by the second CIS 23 and the third CIS 24. The registration roller pair 18 rotates in the opposite direction from the rotation reference position by the angle β about the shaft portion 27b in accordance with the substantially continuously detected skew amount β, and is displaced in the direction of the arrow R1 from the movement reference position by the distance α in accordance with the substantially continuously detected main scanning registration amount α.

[0042] In this way, the sheet S is transported toward the transfer nip while being subjected to skew correction and main scanning registration correction in sequence. At this time, the rotation speed of the registration roller pair 18 (the transport speed until the sheet S reaches the transfer roller 8) is changed so as to match the timing with the toner image on the photosensitive drum 4. 14, the sheet S is transported toward the transfer nip portion, and an image is transferred to a desired position on the sheet S. Thereafter, a contact / separation means (not shown) is operated to move the driven roller of the transport roller pair 17 to a pressure contact position, thereby assisting the transport of the sheet S by the registration roller pair 18 and preparing for the transport operation of the next sheet S to be transported. Thereafter, when the trailing edge of the sheet S passes through the pair of registration rollers 18, the pair of registration rollers 18 returns to the rotation reference position and the movement reference position in preparation for skew correction and main scanning registration correction of the sheet S to be conveyed next.

[0043] In the conveying device 45 according to the present embodiment, the reference color of the sheet S used is set to white. This is because white sheets are generally used frequently. Therefore, the conveying device 45 is configured so that the side edge Sa of the sheet S can be detected with high accuracy by each of the CISs 22, 23, and 24, assuming that white sheets, which are the reference color, are mainly used. In the conveying device 45, the portions of the device body of the conveying device 45 that face each of the CISs 22, 23, and 24 with the conveyed sheet S therebetween are often formed in a color with high light absorption, such as black. As a result, the light emitted from the light-emitting portion of each of the CISs 22, 23, and 24 has a low incidence rate of reflected light to the light-receiving portion on the outside of the sheet S, with the side edge Sa of the white sheet S as the boundary, and a high incidence rate of reflected light to the light-receiving portion on the inside of the sheet S. As a result, the overall output values ​​of each of the CISs 22, 23, and 24 have a clear difference in height with the position corresponding to the side edge Sa of the sheet S as the boundary, and the side edge Sa of the sheet S can be detected with high accuracy.

[0044] However, when a sheet S having a color with a different reflectance compared to the reference color white, such as a color with low reflectance such as black or gray, is transported, the side edge Sa of the sheet S cannot be accurately detected by each CIS 22, 23, and 24 with the previous settings. As described above, the parts of the device body of the conveying device 45 facing each CIS 22, 23, 24 are often formed in a color with high light absorption, such as black. Therefore, when a black or gray sheet S is conveyed, the incidence rate of reflected light to the light receiving section of the light emitted from the light emitting section of each CIS 22, 23, 24 is low on both the inside and outside of the sheet S, with the side edge Sa as the boundary. As a result, the overall output value of each CIS 22, 23, 24 is unlikely to have a clear difference in height with the position corresponding to the side edge Sa of the sheet S as the boundary, and the side edge Sa of the sheet S is not accurately detected. Therefore, if this continues, the skew amount and main scanning registration amount of the sheet S cannot be accurately detected by each CIS 22, 23, 24, and high-precision skew correction and main scanning registration correction cannot be performed.

[0045] In order to prevent such a problem, when the type of sheet S is changed and the reference color is replaced with a different color, the adjustment operation of each CIS 22, 23, 24 is performed. However, in the conventional configuration, it is assumed that the detection and position correction of the sheet are performed two or more times, and there is a problem that it cannot be performed in an apparatus that performs detection and position correction only once due to the constraints of the configuration. In addition, in the sheet reflectance detection using the detection means, it is assumed that the sheet can be detected in the first detection using the reference setting, so the reference setting is essential, and it cannot be applied to a sheet that cannot be detected in the reference setting, and further there is a problem that the position of the sheet cannot be corrected with high accuracy. Furthermore, there is a problem that malfunctions and sheet conveyance jams occur because the position correction is performed using the first detection result. The adjustment operation of each CIS 22, 23, 24 in the present invention that solves these problems will be described below.

[0046] Prior to describing the adjustment operation, there will be described the configuration of each of the CISs 22, 23, and 24 used in this embodiment. The same contact image sensor is used for each of the CISs 22, 23, and 24, and the configuration of the first CIS 22 will be described as a representative example. As shown in Fig. 15(a) as viewed from the left of Fig. 3, the first CIS 22 has two light-emitting units 22a, a lens array 22b, and a light-receiving unit 22c. The light-emitting unit 22a has a plurality of light sources made of LEDs, and the lens array 22b and the light-receiving unit 22c are divided into a plurality of units corresponding to the plurality of light sources. Fig. 15(b) is a view of Fig. 15(a) as viewed from the right. 15(b), each light-emitting unit 22a is attached to an immovable member 48 that constitutes the main body of the transport device 45. The immovable member 48 is provided with an opening 48a that passes the light emitted from the light-emitting unit 22a.

[0047] As shown in Fig. 15, the sheet S passes under each light-emitting unit 22a and the lens array 22b. At this time, the light emitted from each light source of the light-emitting unit 22a is reflected by the sheet S and then received by the light-receiving unit 22c via the lens array 22b. However, in areas where the sheet S does not pass, the light emitted from the light-emitting unit 22a is not reflected by the sheet S, so the light received by the light-receiving unit 22c is only the light reflected by the device body, and the amount of received light is reduced. As a result, the side edge Sa of the sheet S differentiates between the area of ​​the light-receiving unit 22c where the amount of received light is high and the area of ​​the light-receiving unit 22c where the amount of received light is low. This boundary is detected as the side edge Sa of the sheet S. As described above, the second CIS 23 has a light-emitting section 23a, a lens array 23b, and a light-receiving section 23c, although not shown, and the third CIS 24 has a light-emitting section 24a, a lens array 24b, and a light-receiving section 24c, although not shown.

[0048] Next, the control means 36 that functions as an adjustment means for adjusting the operations of the CISs 22, 23, and 24 will be described. 6, the control means 36 is provided with an output adjustment unit 46 that adjusts the output of each of the CISs 22, 23, and 24. The output adjustment unit 46 adjusts the number of emissions and the amount of emission of light from the multiple light sources of the light-emitting units 22a, 23a, and 24a of each of the CISs 22, 23, and 24, based on signals from the light-receiving units 22c, 23c, and 24c of each of the CISs 22, 23, and 24. This adjustment operation will be described later. Each CIS 22, 23, 24, whose output is adjusted by the output adjustment unit 46, is provided with a recording means 22d, 23d, 24d capable of recording adjustment data according to the type of sheet S. The recording means 22d, 23d, 24d is composed of a non-volatile memory such as a ROM or a flash memory, and stores the number of lights emitted and the amount of light emitted by the light-emitting units 22a, 23a, 24a according to the color or light reflectance of the sheet S.

[0049] Based on the above-mentioned configuration, the adjustment operation of each of the CISs 22, 23, and 24 will be described with reference to the operation diagrams shown in FIGS. 16 to 20 and the flowchart shown in FIG. When a start key (not shown) is pressed after the adjustment operations of the CISs 22, 23, and 24 are set on the operation panel 37 (ST21), one sheet S is separated and fed from the paper feed unit 12 (ST22). The fed sheet S is fed by the paper feed roller 19 and each of the transport roller pairs 16, and is then further transported by the transport roller pair 17 as shown in FIG. The conveyed sheet S has its leading edge contacted with the nip portion of the stopped registration roller pair 18, and is further conveyed slightly from that state by the conveying roller pair 17. As a result, the skew state of the sheet S, which is inclined as shown by the dashed line in Fig. 17, is corrected as shown by the solid line (ST23). Note that, in this embodiment, the skew correction of the sheet S is performed by bringing the sheet S into contact with the nip portion of the registration roller pair 18, but the skew correction may be performed by bringing the sheet S into contact with a member other than the registration roller pair 18.

[0050] When the skew correction of the sheet S is completed, the pair of registration rollers 18 starts rotating and the sheet S is transported downstream. When the pair of registration rollers 18 starts transporting the sheet S, a contact / separation means (not shown) is operated to displace the driven roller of the pair of transport rollers 17 to a separated position. Then, when an encoder (not shown) that detects the number of rotations of the first drive motor 25 detects that the sheet S has been transported to a position where the leading edge can be detected by the third CIS 24 as shown in FIG. 18, the rotation of the pair of registration rollers 18 is stopped (ST24). Thereafter, the third drive motor 33 is operated, and the pair of registration rollers 18 is displaced upward in Fig. 18 while sandwiching the sheet S. Then, when the third drive motor encoder 44 detects that the pair of registration rollers 18 has been displaced from the position shown by the dashed line in Fig. 19 to the position shown by the solid line in Fig. 19, that is, the position where the third CIS 24 is completely covered by the sheet S, the operation of the third drive motor 33 is stopped, and the pair of registration rollers 18 and the sheet S are positioned (ST25).

[0051] Next, the control means 36 sends an operation command to the third CIS 24 to start detecting the sheet S (ST26). This causes light to be emitted from the light emitting unit 24a of the third CIS 24, and the emitted light is reflected by the sheet S and detected by the light receiving unit 24c. Here, the control means 36 judges whether the transmitted light can be detected by the light receiving unit 24c when all the light sources of the light emitting unit 24a are operated at the maximum value (ST27). If it is judged that the transmitted light can be detected, the control means 36 adjusts the output level of the light emitting unit 24a so that the light receiving unit 24c can detect the reflected light when the light sources are operated with the minimum number and light amount. Then, when the output level capable of detecting the sheet S is determined, the determined output level is linked to the type and light reflectance of the sheet S used, and recorded in the recording means 24d (ST28). This record is also recorded in the recording means 22d and 23d of the other CISs 22 and 23 in the same manner.

[0052] When the output level adjustment operation and recording operation of the third CIS 24 are completed, the third drive motor 33 is operated again to return the pair of registration rollers 18 to the reference position, and the sheet S that was occupying the position shown by the dashed line in Figure 20 is returned to the initial position shown by the solid line (ST29). When the pair of registration rollers 18 is displaced to the reference position, the third CIS 24 detects the main scanning registration amount of the sheet S, and the main scanning registration correction operation is performed in the same manner as described above (ST30). Then, the second correction operation is performed in the same manner as described above, and the sheet S is transported to the transfer nip portion to perform the image forming operation (ST31). If the control means 36 judges in step ST21 that the adjustment operation is not to be performed, the process jumps to step ST31, where the series of adjustment operations are omitted and the image forming operation is performed. Also, if the control means 36 judges in step ST27 that the sheet S cannot be detected, a message to that effect is displayed on the operation panel 37, and the operation is terminated.

[0053] As described above, according to the present invention, when adjusting each of the CISs 22, 23, and 24, the pair of registration rollers 18 that sandwich the sheet S is displaced toward the outside of the sheet conveying path by the third drive motor 33 until the sheet S covers the third CIS 24. Thereafter, the control means 36 adjusts the output of the third CIS 24 so that the third CIS 24 detects the sheet S. Therefore, a wide variety of sheets S can be correctly detected by each of the CISs 22, 23, and 24 without performing detection and correction multiple times and without performing a reference adjustment in advance. This makes it possible to provide a conveying device that can accurately perform skew correction and main scanning registration correction of the sheet S with simple adjustments. In the present invention, the displacement of the registration roller pair 18 by the operation of the third drive motor 33 is performed after the contact / separation means (not shown) is operated to displace the driven roller of the conveying roller pair 17 to the separated position. This reduces the force acting on the sheet S and improves the accuracy of the main scanning registration correction.

[0054] Furthermore, in the present invention, the third drive motor 33 corrects the amount of positional deviation in the width direction of the sheet S, i.e., the amount of main scanning registration, based on the results of edge position detection of the sheet S from each of the CISs 22, 23, and 24. This makes it possible to accurately perform main scanning registration correction of the sheet S. In the present invention, each CIS 22, 23, 24 has a light-emitting unit 22a, 23a, 24a including a plurality of light sources and a light-receiving unit 22c, 23c, 24c, and the control means 36 adjusts the number of lights emitted and the amount of light emitted by each of the light-emitting units 22a, 23a, 24a during adjustment. This allows fine adjustment. In addition, in the present invention, when the third CIS 24 detects the sheet S, the number of emitted light and the amount of emitted light of the light source of the light-emitting unit 24a are adjusted based on the output of the light-receiving unit 24c. This allows the settings of the CISs 22, 23, and 24 to be changed according to the sheet S being used, and allows detection operations to be performed that are compatible with a wide variety of sheets S.

[0055] Furthermore, in the present invention, the sheet S that is moved out of the transport path during the adjustment operation of each of the CISs 22, 23, and 24 is returned to its original position after the adjustment of each of the CISs 22, 23, and 24. This allows the sheet S used during the adjustment operation to be used in the image formation operation without being wasted, thereby reducing costs and improving the efficiency of image formation. Furthermore, in the present invention, each CIS 22, 23, 24 has a recording means 22d, 23d, 24d capable of recording adjustment data for each type of sheet S, and the control means 36 adjusts each CIS 22, 23, 24 based on the adjustment data recorded in each recording means 22d, 23d, 24d. This allows the adjustment operation to be performed based on the information of the sheet S recorded in advance, making the adjustment operation efficient. In the present invention, the immovable member 47 supporting each of the CISs 22, 23, and 24 has an opening 47a, and the immovable member 48 supporting each of the CISs 22A, 23A, and 24A has an opening 48a. This allows the light emitted from each of the light-emitting units 22a, 23a, 24a, 22Aa, 23Aa, and 24Aa to be concentrated, preventing erroneous detection of the background.

[0056] As a modification of this embodiment, a light absorbing member 49 may be provided on the device main body (not shown) below the light emitting units 22a, 23a, 24a and the lens arrays 22b, 23b, 24b as shown in Fig. 22. As the light absorbing member 49, a brushed black member, specifically a felt material, is used. This reduces the reflectance of the light emitted from the light emitting unit by the device body, making it possible to reduce the occurrence of false detections.

[0057] Next, a second embodiment of the present invention will be described. Fig. 23 shows a conveying device 50 used in the second embodiment of the present invention. This conveying device 50 is different from the conveying device 45 shown in the first embodiment in that it does not have the first CIS 22 and the second CIS 23. In addition, the conveying device 45 has a holding member 30 that rotatably supports the registration roller pair 18 and is supported rotatably relative to the frame 27, while the conveying device 50 has a holding member 30 that is not rotatably supported relative to the frame 27. In addition, the conveying device 45 has a second drive motor 31 that functions as a skew correction means, while the conveying device 50 has a holding member 30 that does not rotate and therefore does not have the second drive motor 31.

[0058] Next, the operation of the conveying device 50 will be described. First, as shown in FIG. 23, the sheet S fed from the paper feed unit 12 is nipped and conveyed by the conveying roller pair 17 toward the registration roller pair 18. The conveyed sheet S contacts its leading edge with the nip portion of the registration roller pair 18 that is stopped, and is further conveyed slightly from that state by the conveying roller pair 17. As a result, the skew state of the sheet S, which is inclined as shown by the dashed line in FIG. 24, is corrected as shown by the solid line. In this configuration, the registration roller pair 18 functions as a skew correction means. In this embodiment, the sheet S is brought into contact with the nip portion of the registration roller pair 18 to correct the skew of the sheet S, but the sheet S may be brought into contact with a member other than the registration roller pair 18 to perform the skew correction. In this case, the other member with which the leading edge of the sheet S comes into contact functions as the skew correction means.

[0059] When the skew correction of the sheet S is completed, the pair of registration rollers 18 rotate to transport the sheet S downstream, and a contact / separation means (not shown) is operated to displace the driven roller of the pair of transport rollers 17 to the separated position. Then, when the sheet S is transported until the leading edge is detected by the third CIS 24 as shown in FIG. 25, the rotation of the pair of registration rollers 18 is stopped. When the side edge Sa of the sheet S is detected by the third CIS 24, the control means 36 detects the main scanning registration amount of the sheet S from the position of the side edge Sa. After that, the control means 36 sends an operation command to the third drive motor 33 to drive the third drive motor 33, and the registration roller pair 18 is displaced in a direction to offset the detected main scanning registration amount. At this time, the third drive motor 33 functions as a position deviation correction means. In this way, the sheet S is conveyed toward the transfer nip portion after the skew correction and main scanning registration correction are performed. At this time, the rotation speed of the registration roller pair 18 is changed so as to match the timing with the toner image on the photosensitive drum 4.

[0060] Next, the adjustment operation of the third CIS 24 in the second embodiment will be described. When a start key (not shown) is pressed after the adjustment operation of the third CIS 24 is set on the operation panel 37, one sheet S is separated and fed from the paper feed unit 12. The fed sheet S is transported by the paper feed roller 19 and each transport roller pair 16, and then further transported by the transport roller pair 17 as shown in FIG. The conveyed sheet S has its leading edge contacted with the nip portion of the stopped registration roller pair 18, and is further conveyed slightly from that state by the conveying roller pair 17. As a result, the skewed state of the sheet S, as shown by the dashed line in FIG. 24, is corrected as shown by the solid line. In this configuration, the registration roller pair 18 functions as a skew correction means. Note that in this embodiment, the skew correction of the sheet S is performed by bringing the sheet S into contact with the nip portion of the registration roller pair 18, but the skew correction may also be performed by bringing the sheet S into contact with a member other than the registration roller pair 18. In this case, the other member with which the leading edge of the sheet S comes into contact functions as the skew correction means.

[0061] When the skew correction of the sheet S is completed, the pair of registration rollers 18 rotate to transport the sheet S downstream, and a contact / separation means (not shown) is operated to displace the driven roller of the pair of transport rollers 17 to the separated position. Then, when an encoder (not shown) that detects the number of rotations of the first drive motor 25 detects that the sheet S has been transported to a position where the leading edge can be detected by the third CIS 24 as shown in FIG. 25, the rotation of the pair of registration rollers 18 is stopped. Thereafter, the third drive motor 33 is operated, and the pair of registration rollers 18 is displaced upward in Fig. 25 while sandwiching the sheet S. Then, when the third drive motor encoder 44 detects that the pair of registration rollers 18 has been displaced from the position shown by the dashed line in Fig. 26 to the position shown by the solid line, that is, to the position where all of the light-emitting units 24a, the lens array 24b, and the light-receiving units 24c of the third CIS 24 are covered by the sheet S, the operation of the third drive motor 33 is stopped, and the pair of registration rollers 18 and the sheet S are positioned at a predetermined detection position.

[0062] Next, the control means 36 sends an operation command to the third CIS 24, and starts detecting the sheet S in the same manner as in the first embodiment. Then, when the output level of the light-emitting unit 24a capable of detecting the sheet S is determined in the same manner as in the first embodiment, the determined output level is linked to the type and light reflectance of the sheet S used, and recorded in the recording means 24d. When the output level adjustment operation and the recording operation of the third CIS 24 are completed, the third drive motor 33 is operated again to return the registration roller pair 18 to the reference position, and the sheet S, which occupied the detection position shown by the dashed line in Fig. 27, is returned to the position shown by the solid line. When the registration roller pair 18 is displaced to the reference position, the main scanning registration amount of the sheet S is detected by the third CIS 24, and a main scanning registration correction operation is performed in the same manner as the operation described above. After the correction operation is completed, the registration roller pair 18 is rotated to transport the sheet S toward the transfer nip portion, and an image forming operation is performed. This second embodiment also has the same effect as the first embodiment, due to the configuration using one CIS as the end position detection means.

[0063] In the above embodiment and each modified example, an example was shown in which a monochrome copier 1 was used as an image forming apparatus, but the image forming apparatus is not limited to this, and the present invention is also applicable to printers, facsimiles, multifunction machines, and monochrome and full-color devices thereof. In addition, in each embodiment, a configuration was shown in which a sheet S was used as a recording medium on which an image is formed, but the sheet S also includes cardboard, postcards, envelopes, plain paper, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, OHP films, resin films, etc., and any material that is sheet-like, capable of forming an image, and transmits or reflects light may be used.

[0064] Although a preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the spirit of the present invention described in the claims, unless otherwise specifically limited in the above description. For example, in the above-described embodiments, a reflective type is used as each of the CISs 22, 23, 24 functioning as the end position detection means, but a transmissive CIS or other detection sensor may be used as the end position detection means. The effects described in the embodiments of the present invention are merely examples of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. [Explanation of symbols]

[0065] 1. Image forming equipment (copying machines) 17 Second clamping roller (pair of conveying rollers) 18 First clamping roller (pair of registration rollers) 22, 22A End position detection means (first CIS) 22a, 22Aa, 23a, 23Aa, 24a, 24Aa Light-emitting part 22c,22Ac,23c,23Ac,24c,24Ac light receiving part 22d, 23d, 24d Recording means 23, 23A End position detection means (second CIS) 24, 24A End position detection means (third CIS) 33 Position deviation correction means (third drive motor) 36 Adjustment means (control means) 45 Transport Equipment 47,48 Immovable parts 47a,48a opening 49 Light absorbing material S Recording medium (sheet) [Prior art documents] [Patent documents]

[0066] [Patent Document 1] JP 2018-203538 A

Claims

1. a first nip roller consisting of a pair of rollers for nipping and conveying a recording medium; a second nip roller arranged upstream of the first nip roller in a conveying path for the recording medium, the second nip roller being a pair of rollers that can be moved toward and away from each other; a positional deviation correction unit that corrects a positional deviation in a width direction of the recording medium transported along the transport path; an end position detection unit that is provided from the inside to the outside of the conveying path in the width direction and detects an end position of the recording medium in the width direction; an adjustment means for adjusting an output of the end position detection means; A conveying device in which, when adjusting the end position detection means, the conveying of the recording medium is stopped when the leading end of the recording medium reaches the end position detection means, the position shift correction means moves the recording medium toward the outside of the conveying path until it reaches a position covering the end position detection means, and the adjustment means adjusts the output of the end position detection means so that the end position detection means detects the recording medium.

2. 2. The conveying device according to claim 1, The conveying device according to claim 1, wherein the position deviation correction means operates after the second pinch roller releases the recording medium from the nip.

3. 3. The conveying device according to claim 1, The conveying device is characterized in that the positional deviation correction means corrects the amount of positional deviation in the width direction of the recording medium based on the detection result by the end position detection means.

4. 4. The conveying device according to claim 1, A conveying device characterized in that the end position detection means has a light-emitting unit including a plurality of light sources and a light-receiving unit that outputs a signal corresponding to the amount of light irradiated from the light-emitting unit and reflected or transmitted by the recording medium, and the adjustment means adjusts the number and amount of light emitted by the light-emitting unit.

5. 5. The conveying device according to claim 4, the adjustment means adjusts the number of emitted lights and the amount of emitted light based on an output from the light receiving portion when the end position detection means detects the recording medium.

6. 6. The conveying device according to claim 1, A transport device comprising: a recording medium transport path that is moved to the outside of the transport path during adjustment of the edge position detection means, the recording medium being transported back to its original position after the adjustment of the edge position detection means.

7. 7. The conveying device according to claim 1, A conveying device characterized in that the end position detection means has a recording means capable of recording adjustment data for each type of recording medium in advance, and the adjustment means adjusts the end position detection means based on the adjustment data recorded in the recording means.

8. 5. The conveying device according to claim 4, A conveying device characterized in that the end position detection means is supported by an immovable member, and an opening is provided at a portion of the immovable member corresponding to the end position detection means to allow light irradiated from the light emitting unit to pass through.

9. 9. An image forming apparatus comprising the conveying device according to claim 1.

Images