JP2015086040A - Sheet transportation device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize control on a sheet that has been transported in a state in which a position in width direction is being displaced.SOLUTION: A controller 50, in a case where a displacement amount X is such a degree as slightly exceeding an upper limit amount (3 mm) by an amount (5 mm or less), continues transportation of a sheet instead of assuming it as jamming (abnormal transportation). The controller 50, in a case where the displacement amount X significantly exceeds the upper limit amount (3 mm) by an amount (larger than 5 mm), determines that abnormal transportation has occurred, and stops transportation of the sheet. It is determined that abnormal transportation (jamming) has occurred.

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet, and an image forming apparatus including the sheet conveying apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image on a sheet is provided with a width direction correction mechanism that corrects a position in a direction (width direction) orthogonal to the sheet conveyance direction.

  Japanese Patent Application Laid-Open No. 2004-228561 describes a configuration in which the sheet is moved in the width direction based on a detection result of the detection unit and a detection result of the detection unit as a width direction configuration mechanism. More specifically, in Patent Document 1, a registration roller pair (hereinafter referred to as a registration roller pair as appropriate) that detects the edge of the sheet by CIS and holds the sheet by the amount of deviation from the reference position. The structure which moves this to the width direction is described.

JP2013-126914A

  By the way, the amount that the registration roller pair can move in the width direction has a limit (upper limit) for various reasons (space, skew, productivity, etc.). This will be described below.

  When the amount that the registration roller pair can move in the width direction is increased, it is necessary to secure a space correspondingly, leading to an increase in the size of the apparatus.

  Further, depending on the characteristics of the apparatus and the characteristics of the sheet, if the amount that the registration roller pair can be moved in the width direction is increased, the sheet may be skewed. This is because the registration roller pair moves in the width direction while sandwiching the sheet.

  Further, the registration roller pair moved in the width direction for the preceding sheet needs to return to the position before moving (home position) before the leading edge of the succeeding sheet reaches the registration roller pair. Therefore, if the amount that the registration roller pair can be moved in the width direction is increased, the time required to return the registration roller pair to the home position becomes longer. Therefore, it is necessary to increase the interval (distance / time) between the preceding sheet and the succeeding sheet. That is, this may lead to a decrease in productivity.

  Japanese Patent Application Laid-Open No. 2004-228561 describes what kind of control is performed when a sheet is conveyed in a state of being displaced from the reference position by an amount larger than the amount that the registration roller pair can move in the width direction. Not.

  The present invention optimizes control for a sheet that has been conveyed in a state in which the position in the width direction has shifted.

  The present invention includes a conveyance unit that nipping and conveying a sheet, a detection unit that detects an end in a width direction orthogonal to the conveyance direction of the sheet, and a moving unit that moves the conveyance unit that nipping the sheet in the width direction. And a control unit that controls the moving unit based on a detection result of the detection unit, and the control unit has a position of an end in the width direction of the sheet detected by the detection unit, When the distance from the reference position is greater than the first predetermined amount and less than or equal to the second predetermined amount, the transport unit is moved by a third predetermined amount that is less than or equal to the first predetermined amount; The control unit performs an abnormality process when the position of the end in the width direction of the sheet detected by the detection unit is separated from the reference position by an amount larger than a second predetermined amount. This is a sheet conveying apparatus.

  According to the present invention, it is possible to optimize control for a sheet that has been conveyed in a state in which the position in the width direction is shifted.

The figure which looked at the sheet conveyance device to which a 1st embodiment was applied from the device front side The figure which looked at the sheet conveyance device to which a 1st embodiment was applied from the device back side. Detailed view of the transport roller attaching / detaching mechanism of the first embodiment 1 is a block diagram of an image forming apparatus according to a first embodiment. Flowchart of image forming apparatus according to first embodiment Conveying diagram and driving diagram of the first embodiment 1 is a diagram illustrating an overall configuration of an image forming apparatus to which a first embodiment is applied.

(First embodiment)
(Configuration of the entire image forming apparatus)
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 7 shows a schematic sectional view of a color digital printer as an example of an image forming apparatus to which the sheet conveying apparatus of the present invention is applied.

  First, the image forming unit will be described. The surfaces of the four photosensitive drums 101a to 101d are charged with uniform charges by the charging rollers 102a to 102d, respectively. Each of the laser scanners 103a to 103d receives yellow (Y), magenta (M), cyan (C), and black (K) image signals, and irradiates the drum surface with laser light in accordance with the image signals, and charges Is neutralized to form a latent image.

  The latent images formed on the photosensitive drum are developed with yellow, magenta, cyan, and black toners by developing units 104a to 104d, respectively. The toner developed on each photosensitive drum is sequentially transferred to an intermediate transfer body belt 106, which is an endless belt-like image carrier, by primary transfer rollers 105a to 105d, and a full color toner image is formed on the intermediate transfer body belt 106. It is formed.

  A sheet fed from one of the sheet feeding cassettes 111 and 112 is conveyed toward the registration roller pair (conveying unit) 120 by the upstream roller pair 115. Similarly, the sheet fed from the manual feeding unit 113 is also conveyed to the registration roller pair 120. The toner image on the intermediate transfer belt 106 is controlled so that there is no deviation between the sheet conveyed by the registration roller pair 120 and the image. The toner image is transferred to the sheet by the secondary transfer outer roller 109. Thereafter, the toner image is heated and pressed by the fixing device 110 and fixed on the sheet. Thereafter, the sheet is discharged from the discharge unit 119a or 119b to the outside of the apparatus main body.

  The side regulating plate has a function of preventing the skew of the sheet and the displacement in the width direction that occur during sheet feeding. However, in actuality, if a slight gap is generated between the side regulating plate and the sheet, the skew of the sheet and the positional deviation in the width direction may occur. Further, the fed sheet may cause skew and lateral registration misalignment during conveyance.

  Therefore, in this embodiment, the leading edge of the conveyed sheet is brought into contact with the nip portion of the stopped registration roller pair 120, and the leading edge of the sheet is moved along the nip portion while forming a loop on the sheet. Correct the skew of the sheet. At this time, it is necessary to convey the sheet by the upstream roller pair 115 so that the leading edge of the sheet contacts the nip portion of the registration roller pair 120 so that the leading edge of the sheet follows the nip portion.

  Between the registration roller pair 120 and the secondary transfer unit 109, a CIS (Contact Image Sensor) 143 is arranged as a detection unit for detecting the position in the width direction of the sheet (direction orthogonal to the conveyance direction). ing. After starting the conveyance of the sheet by the registration roller pair 120, the position in the width direction of the sheet is corrected by shifting (moving) the registration roller pair 120 in the thrust direction (width direction) based on the detection result by the CIS 143. Is done.

(Registration structure, mechanism explanation)
Next, a first embodiment of the sheet conveying apparatus will be described with reference to the drawings. The sheet conveying device 116 is provided in the middle of a sheet conveying path connecting the sheet feeding cassettes 111 and 112 and the image forming unit. FIG. 1 is a perspective view of the sheet conveying device 116 as viewed from the front side.

  The sheet conveyance path in the vicinity of the registration roller pair 120 includes an upper conveyance guide 121a and a lower conveyance guide 121b, and the lower conveyance guide 121b, which is the upper conveyance guide 121a, is integrally configured. The upper conveyance guide 121 a and the lower conveyance guide 121 b are arranged so as to guide the sheet conveyed from the upstream roller pair 115 to the nip portion of the registration roller pair 120.

  The registration roller pair 120 includes an upper roller (first roller) 120a having a roller made of polyacetal (POM), and a lower roller (second roller) 120b formed by a rubber roller disposed opposite to the upper roller 120a. Have A rotating shaft 120s that rotates integrally with the lower roller 120b is rotatably supported by the lower conveyance guide 121b via a bearing or the like. The upper roller 120a is rotatably supported via a plurality of bearings 122a, b, and c.

  The bearings 122a, b, and c are respectively fixed to the spring hook members 123a, 123b, and 123c that are integrally provided in the transport upper guide 121a so as not to move in the sheet transport direction. The bearings 122a, b, and c are held so as to be movable in a direction away from the lower roller 120b. The springs (biasing portions) 124a to 124f are hooked on the hook portions formed on the spring hook members 123a, 123b, and 123c so that the upper roller 120a is pressed against the lower roller 120b, and the sheet A clamping force is applied. That is, the spring applies a clamping force (biasing force) to the registration roller pair 120.

  In FIG. 1, a registration motor 61 generates a driving force for rotating the registration roller pair 120, and an upstream roller driving motor 62 generates a driving force for rotating the upstream roller pair 115.

  The shift mechanism (moving unit) that moves the sheet in the width direction is as follows. The lower roller 120b of the registration roller pair 120 is fixed to the rotation shaft 120S, and the rotation shaft 120S is fixed to the apparatus main body so as to be movable in the width direction. As the rotation shaft 120S moves in the width direction, the upper roller 120a and the lower roller 120b move together in the width direction.

  The pinion gear 44 is rotated by the driving force from the shift motor 43 to move the rack 45 in translation. The rack 45 is rotatable in the rotation direction with respect to the rotation shaft 120S, and is fixed and supported in the width direction. Thereby, the movement operation in the width direction of the registration roller pair 120 is possible, and the sheet sandwiched by the registration roller pair 120 can be moved in the width direction.

  The idler gear 63 has a wider tooth width than the input gear 68. This is for maintaining the meshing of the gears and allowing the registration roller pair 120 to rotate even when the registration roller 120 and the input gear 68 are thrust. It should be noted that the detection of the shift amount in the width direction is performed by CIS 143. The CIS 143 is disposed in front of the image transfer unit in the transport direction. Further, the CIS 143 is arranged so as to be deviated from the center in the width direction. This is because it is sufficient to detect the side edge on one side of the sheet, regardless of the minimum width or maximum width.

  Next, the separation mechanism (release part) 150 that separates the registration roller pair 120 against the urging force of the springs 124a to 124f will be described with reference to FIGS. 2A and 2B are perspective views of the sheet conveying device 116 as viewed from the back side. FIG. 3A is a diagram illustrating a state in which the registration roller pair 120 is attached, and FIG. 3B is a diagram illustrating a separated state.

  The separation mechanism 150 is configured to separate the upper roller 120a from the lower roller 120b, and thereby, the sheet clamping force can be zero (released).

  The driving force from the detachable motor 151 is transmitted to the motor input gear 152, idler gear 153, and cam input gear 154 to drive the cam 155. These are arranged symmetrically in the front of the apparatus main body, and the driving force from the attachment / detachment motor 151 on the back side is transmitted to the front side via the cam shaft 157.

  The outer shape of the cam 155 is eccentric with respect to the rotation center axis, and when the distance from the center axis to the outer shape of the cam is the minimum, the registration roller pair 120 is in a worn state (FIG. 3A). On the other hand, when the distance from the central axis to the cam outer shape is the maximum, the cam 155 pushes up the cam follower 156, so that the registration roller pair 120 is separated (FIG. 3B). The cam follower 156 is provided to be rotatable coaxially with the upper roller 120a, and the cam 155 is provided to be rotatable coaxially with the lower roller 120b. When the cam follower 156 is pushed up by the cam 155, the upper roller 120a is separated from the lower roller 120b. The amount of separation here is 2 mm. In the present embodiment, the cam 155 and the cam follower 156 constitute a separation mechanism (release part) 150.

  As a cam profile in the separated state, a region of 60 degrees has a constant radius, and the torque applied to the cam 155 is almost zero. Thereby, even if the driving force of the detachable motor 151 is turned off, the separated state is maintained.

  Further, the cam 155 is rotatably supported by a bearing or the like with respect to the rotating shaft 120s, and operates independently of driving by the registration motor 61. That is, even if the registration motor 61 rotates the rotating shaft 120s, the cam 155 does not rotate.

  The shift mechanism moves the next member integrally in the width direction. The registration roller pair 120, the conveyance upper guide 121a and the conveyance lower guide 121b, the spring hooking members 123a, b, c, the springs 124a to f, the cam 155, and the cam follower 156 are integrally moved. Note that the cam input gear 154 has a wide tooth width so that the meshing between the cam 155 and the cam input gear 154 is maintained even when the cam 155 is shifted. Therefore, even when the cam 155 is shifted, the driving force from the attachment / detachment motor 151 is transmitted from the cam input gear 154 to the cam 155.

  As shown in the block diagram of FIG. 4, the controller 50 as a control unit is connected to the operation unit 200 and the display unit 210 of the image forming apparatus. The controller 50 is connected to a registration motor 61, an upstream roller drive motor 62, a shift motor (drive source) 43, a detachable motor (drive source) 151, a registration sensor 141, and a CIS 143. The controller 50 is connected to the ROM and RAM. The controller 50 executes the program stored in the ROM storing the program corresponding to the procedure shown in FIG. 5 by using the RAM as a work memory. In addition, the structure using the common display which has the function of the operation part 200 and the function of the display part 210 may be sufficient as this invention.

(Explanation of misalignment correction operation in the width direction)
Next, the positional deviation correction operation in the sheet width direction by the sheet conveying device 116, which is a feature of the first embodiment, will be described with reference to the drawings.

  In the first embodiment, the controller 50 controls the driving of the shift motor 43 based on the detection result of the CIS 143 to move the registration roller pair 120 that sandwiches the sheet in the width direction, so that the sheet width direction Correct the position of. Specifically, the amount of deviation between the position of the end of the sheet detected by the CIS 143 and the reference position (the position of the end serving as the reference when forming an image on the sheet) is corrected for misalignment in the width direction. Calculated as a quantity. The reference position is set for each sheet size, and the controller 50 stores in advance a table in which each sheet size is associated with the reference position of the end in the width direction of the sheet. The controller 50 determines the amount of movement of the registration roller pair 120 in the width direction of the sheet by referring to the table in accordance with the position of the end portion in the width direction detected by the CIS 143. Then, the position in the width direction of the sheet is corrected by shifting (moving) the registration roller pair 120 in the thrust direction (width direction) by the amount of positional deviation correction.

  Here, the amount that the registration roller pair 120 can move in the width direction (hereinafter, appropriately referred to as an upper limit amount) has a limit (upper limit) from the viewpoint of space, skew, productivity, and the like. In the first embodiment, the upper limit amount is set to 3 mm.

  The first embodiment is characterized in the control by the controller 50 when the edge of the sheet detected by the CIS 143 is displaced by an amount larger than 3 mm (upper limit) from the reference position. Hereinafter, the description will be divided into three cases. In the following description, the distance between the position of the end of the sheet detected by the CIS 143 and the reference position of the CIS 143 is referred to as a deviation amount X.

(1) In the case of 0 ≦ deviation amount X ≦ 3 mm In this case, the controller 50 moves the registration roller pair 120 in the width direction by the deviation amount X. Thereby, the position of the sheet in the width direction can be corrected.

(2) When 3 mm (first predetermined amount) <deviation amount X ≦ 5 mm (second predetermined amount) In this case, the controller 50 moves the registration roller pair 120 in the width direction by 3 mm (upper limit amount). . That is, if the deviation amount X is an amount (5 mm or less) that slightly exceeds the upper limit amount (3 mm), the controller 50 continues the sheet conveyance without causing a jam (conveyance abnormality).

  In this case, the controller 50 displays a warning on the display unit 210 provided in the apparatus main body. As this warning display, for example, it is conceivable to display an alarm indicating that the sheet is set correctly.

  This is because it can be considered acceptable for the user as long as the image is slightly shifted in the width direction (in the first embodiment, the correction is made by the upper limit amount to be 2 mm or less). . Rather, in this case, it may be inconvenient for the user if the conveyance of the apparatus main body is stopped as a conveyance abnormality.

(3) When 5 mm (second predetermined amount) <deviation amount X In this case, the controller 50 determines that a conveyance abnormality (jam) has occurred, and uses the motors of the apparatus main body including the registration motor 61. Stop all (perform error processing). That is, when the deviation amount X is an amount (exceeding 5 mm) that greatly exceeds the upper limit amount (3 mm), the controller 50 determines that a conveyance abnormality has occurred and stops conveying the sheet.

  This is because if the sheet is greatly displaced in the width direction (in the first embodiment, even if the upper limit amount is corrected, the amount exceeds 2 mm), any part of the downstream conveyance path. This is because there is a possibility of getting caught. If the sheet is caught in the conveyance path, there is a risk of damaging the components of the apparatus main body.

  Another reason is that if the sheet is greatly displaced in the width direction, it is highly likely that the sheet is skewed at the same time, and the quality of the product (sheet after image formation) is unacceptable to the user. This is because there is a high possibility of being.

  Even when the sheet is conveyed with a large deviation (outside the detection area of the CIS 143), similarly to the above, the controller 50 determines that a conveyance abnormality has occurred and stops conveying the sheet.

  FIG. 5 is a flow of control by the CPU 50, FIG. 6A shows the leading / rear end positions of the sheet in continuous paper passing, and FIG. FIG. In FIGS. 6A and 6B, the horizontal axis is the time axis, and the vertical axis indicates the position of the sheet.

  First, the user executes a print job from the operation unit 200 of the image forming apparatus or from the computer 201 connected to the image forming apparatus directly or via a network (Step 101). When the print job is executed, the sheet feeding operation is started (Step 102), the sheet is conveyed by the upstream roller pair 115 (Step 103), and is conveyed to the registration sensor 141.

  When the registration sensor 141 detects the conveyed sheet, the upstream roller pair 115 stops rotating, and the sheet is temporarily stopped immediately before the nip portion of the registration roller pair 120 (Step 104). After a predetermined time has elapsed, the controller 50 controls the driving of the upstream roller drive motor 62, starts the rotation of the upstream roller pair 115, and makes the sheet tip contact the registration roller pair 120 to form a loop on the sheet. The skew correction operation is performed (Step 105).

  Thereafter, the controller 50 simultaneously restarts the registration roller pair 120 and the upstream roller pair 115 to convey the sheet downstream while maintaining the skew correction state (Step 106).

  The sheet conveyed downstream by the registration pair roller 120 is detected by the CIS 143 at the end position in the width direction of the sheet (Step 107). The controller 50 calculates a deviation amount (deviation amount X) in the width direction between the position of the sheet edge detected by the CIS 143 and the reference position.

  The controller 50 determines which of the above-described pattern 1 to pattern 3 the calculated deviation amount X applies. Specifically, first, the controller 50 determines whether or not the deviation amount X is 3 mm or less (Step 108).

  If the calculated deviation amount X is 0 ≦ deviation amount X ≦ 3 mm, the controller 50 controls the shift motor 43 so as to move the registration roller pair 120 in the width direction by the deviation amount X. (Step 109). As a result, the sheet is adjusted to the reference position.

  When the calculated displacement amount X is 3 mm <displacement amount X ≦ 5 mm (Step 110), the controller 50 controls the shift motor 43 so as to move the registration roller pair 120 in the width direction by 3 mm. (Step 112). In addition, the controller 50 performs a display unit 210 warning display.

  On the other hand, if the calculated displacement amount X is 5 mm <displacement amount X, the controller 50 stops driving the drive source of the apparatus main body including the registration motor 61 (Step 112). Further, the controller 50 displays on the display unit 210 that the jam processing is to be performed.

T ₄ has elapsed from the width direction of the correction start, the sheet is corrected position has been completed is conveyed to the secondary transfer unit, an image transfer to the sheet is performed (Step 113). After the leading edge of the sheet has advanced a predetermined amount beyond the secondary transfer portion, the CPU 50 separates the registration roller pair 120 by the attachment / detachment motor 151 (Step 114, operation time T ₃ ).

Thereafter, the presence / absence of a succeeding sheet is determined (Step 115). If there is a succeeding sheet, the shift motor 43 is driven in the reverse direction by the same amount as the shift amount at Step 108. Thus, the registration roller pair 120 returns to the initial position in the width direction (hereinafter referred to as shift home position operation) (Step 116, operation time T ₄ ). Then, the registration roller is put on after the trailing edge of the preceding sheet exceeds the registration roller pair 120 and before the succeeding sheet reaches the registration roller pair 120 (Step 117, operation time T). ₂ ). If there is no subsequent sheet, the print job is terminated (Step 118).

  That is, in the present embodiment, the controller 50 controls the shift motor 43 and the attachment / detachment motor 151 to move the registration roller pair 120 that sandwiched the sheet in the width direction from the initial position, and then moves the registration roller pair 120. Separate. Thereafter, the controller 50 controls the shift motor 43 and the attachment / detachment motor 151 to move the registration roller pair 120 to the initial position in the width direction in a state where the registration roller pair 120 is separated.

Here, the reason why the shift home position operation is performed in a state where the registration roller pair 120 is separated will be described. This is because the paper interval T ₁ (the time from the trailing edge of the preceding sheet to the leading edge of the succeeding sheet in the registration roller pair 120) is shorter than the shift home position operation time T ₅ . That is, the operation of performing the shift home position operation is not in time after the trailing edge of the preceding sheet passes through the registration roller pair 120 and before the leading edge of the succeeding sheet reaches the registration roller pair 120.

Recent image forming apparatus that is progressing increasingly faster, also set from the fact that stops the sheet at the registration roller pair 120 in the skew correction mechanism as in this embodiment, T ₁ is shorter Often done. Therefore, as described above, it is preferable to perform the shift home position operation in a state in which the registration roller pair 120 is separated before the trailing edge of the preceding sheet still passes the registration roller pair 120.

  In many cases, the rear end portion of the sheet at the time of shifting is still held between a plurality of rollers (upstream roller pair 115 and the like). When the shift operation is performed in this state, a twist is generated in a loop formed between the registration roller pair 120 and the upstream roller pair 115, and a force for turning the sheet is exerted on the registration roller pair 120. If the turning force exceeds the clamping force of the registration roller pair 120, skewing may deteriorate in the registration roller pair 120.

  In general, the pair of registration rollers 120 is set to have a higher clamping pressure than the other conveyance rollers so that the leading edge timing with the image is accurately adjusted, and so that the sheet does not slip during conveyance. There are many. Further, it is desirable to set the clamping pressure as high as possible in order to prevent slipping due to the twisting of the loop.

  In particular, cardboard having a large basis weight has high rigidity, and a greater turning force acts, so that slipping easily occurs. For this reason, the clamping pressure of the registration roller pair 120 of the present embodiment is set to 4 kgf with respect to 1 kgf of the normal conveyance roller pressure. As described above, the clamping force of the registration roller pair 120 is a relatively high clamping pressure for the transport roller. Therefore, if this is separated, a large rubbing force is generated between the cam surface of the cam 155 and the cam follower 156 described above. Will work.

  As in the technique described in Japanese Patent Application Laid-Open No. 2008-50069, the cam follower shifts together with the conveying roller. On the other hand, when the cam does not shift, the rubbing force is generated when the shift home position operation is performed in a separated state. It becomes resistance. As a result, not only the load torque due to the shift motor increases, but also wear due to rubbing advances, an appropriate roller separation amount cannot be obtained, and the shift mechanism is deformed by the rubbing force, so that the shift accuracy is improved. There was a case where it was lowered.

  In this embodiment, the separation mechanism and the shift mechanism as described above are provided, and the above-described sliding force can be configured not to contribute to the shift home position operation.

  Specifically, in this embodiment, the registration roller pair 120, the springs 124a to 124f that apply the clamping pressure to the registration roller pair 120, the cam 155, and the cam follower 156 are all shifted integrally. Furthermore, in this embodiment, the profile of the cam 155 is set so that the separated state is maintained even when the drive of the attachment / detachment motor 151 is turned off when the registration roller pair 120 is separated by driving the cam 155.

  Therefore, according to this embodiment, even if the shift home position operation is performed in a state where the registration roller pair 120 is separated, the rubbing force by the springs 124a to 124f is not affected. Thereby, the following effects are acquired.

  Since the torque required for the shift can be reduced, the size of the shift motor 43 can be reduced. In addition, since the deformation of the shift mechanism due to the rubbing force can be reduced, the shift accuracy can be improved.

  Further, the registration roller pair 120 does not have a small inertial force, and tends to have a large acceleration torque and deceleration torque during the shift operation. According to the present embodiment, since there is no influence of torque due to the rubbing force, the acceleration and deceleration can be increased correspondingly, and the time required for the shift operation can be further shortened. This can be applied to an image forming apparatus with higher productivity.

  Since the clamping pressure of the registration roller pair 120 can be set high, slip during conveyance to the image forming unit and slip during shift are less likely to occur, and image printing accuracy is improved.

  In the above description, as a pair of conveyance rollers that are shifted in the width direction and separated from each other, a registration roller pair provided upstream from an image forming unit that forms an image on a sheet is described as an example. The scope to which the invention is applied is not limited to this. For example, a sheet aligning apparatus or the like also includes a pair of conveying rollers that perform correction in the width direction, and the same effect can be expected even if the configuration of the present embodiment is applied thereto.

  In the above description, the configuration in which the tension springs 124a to 124f are applied in a U shape has been described as an example, but the scope to which the present invention is applied is not limited to this. In other words, the urging portion that applies the clamping force to the conveying roller pair may be a compression spring, a leaf spring, or the like.

  In the above description, the configuration in which the registration roller pair 120 is moved in the width direction by the upper limit amount (3 mm) when 3 mm <deviation amount X ≦ 5 mm has been described, but the present invention is limited to this. Should not. That is, when 3 mm <displacement amount X ≦ 5 mm, the registration roller pair 120 may be moved in the width direction by an amount equal to or less than the upper limit amount (third predetermined amount), for example, 2.9 mm. .

  Further, the upper limit amount may be changed according to the type of sheet. For example, the upper limit amount may be set to 4 mm larger than 3 mm for a sheet having a low basis weight or a sheet having a short length in the conveyance direction.

  In the above-described embodiment, the description has been made using specific numerical values. However, the numerical values should be changed as appropriate according to the characteristics of the apparatus, and the present invention should not be limited to this.

43 Shift motor 50 CPU (control unit)
116 Sheet conveying device 120 Registration roller pair (conveying unit)
120a Upper roller 120b Lower roller 143 CIS (detection unit)

Claims (8)

A conveyance unit for nipping and conveying the sheet;
A detection unit for detecting an end portion in the width direction orthogonal to the conveyance direction of the sheet;
A moving unit that moves the conveying unit sandwiching the sheet in the width direction;
A control unit for controlling the moving unit based on a detection result of the detection unit,
When the position of the end in the width direction of the sheet detected by the detection unit is separated from the reference position by an amount that is greater than the first predetermined amount and equal to or less than the second predetermined amount, , Moving the transport unit by a third predetermined amount that is less than or equal to the first predetermined amount,
Further, the control unit performs an abnormality process when the position of the end portion in the width direction of the sheet detected by the detection unit is separated from the reference position by an amount larger than a second predetermined amount. A sheet conveying apparatus characterized in that it performs.   The sheet conveying apparatus according to claim 1, wherein the third predetermined amount is the same amount as the first predetermined amount.   The sheet conveying apparatus according to claim 1, wherein the control unit stops driving of the conveying unit as the abnormality processing.   When the position of the end in the width direction of the sheet detected by the detection unit is separated from the reference position by the first predetermined amount or less, the control unit is separated from the conveyance unit. The sheet conveying apparatus according to any one of claims 1 to 3, wherein the sheet conveying apparatus is moved only by the distance.   The said control part calculates the deviation | shift amount from the said reference position of the position of the edge part of the said width direction of the sheet | seat detected by the said detection part. The sheet conveying apparatus according to the description. It has a display part provided in the device body,
In the control unit, the position of the end in the width direction of the sheet detected by the detection unit is separated from the reference position by an amount greater than the first predetermined amount and not more than the second predetermined amount. In such a case, a warning is displayed on the display unit, and the sheet conveying apparatus according to any one of claims 1 to 5. The transport unit includes a pair of registration rollers that transports the sheet to the image forming unit,
The sheet conveying apparatus according to claim 1, wherein the reference position is a position that serves as a reference when an image is formed on a sheet by the image forming unit. An image forming unit for forming an image on a sheet;
A sheet conveying device according to any one of claims 1 to 7,
An image forming apparatus comprising:

Images