JP6864859B2 - Skew correction device, paper transfer device and image forming device - Google Patents

Description

The present invention relates to a skew correction device, a paper transport device, and an image forming device.

Conventionally, there is known a skew correction device that bends the paper by abutting the tip of the paper tilted with respect to the paper transport direction against the abutting member or the nip portion of the roller pair to correct the tilt (skew) of the paper tip. ing.

For example, Patent Document 1 describes a skew correction device in which transport roller pairs and resist roller pairs are sequentially arranged on a paper transport path from the upstream side to the downstream side in the paper transport direction. It is disclosed. The skew correction device includes a gate member as an abutting portion that is coaxially supported coaxially with the lower roller of the resist roller pair of rollers so as to be rotatable integrally with the lower roller. The gate member includes a protrusion having an abutting surface that projects into the paper transport path and abuts the tip of the paper. The protruding portion can be moved to an abutting position where the tip of the paper abuts against the abutting surface and a retracting position where the paper is retracted from the paper transport path by rotating the gate member by the driving means of the resist roller pair.

Then, with the protruding portion positioned at the abutting position in the paper transport path, the tip of the paper transported from the upstream side in the paper transport direction by the transport roller pair is abutted against the abutting surface of the protruding portion. After that, by rotating the transfer roller pair to continue the transfer of the paper, the paper is bent into a loop shape and the inclination of the paper tip is corrected. After that, the rotation of the transfer roller pair is stopped to stop the transfer of the paper. After that, the resist roller pair is rotated to retract the protruding portion from the abutting position to the retracted position to stop the rotation of the resist roller pair. As a result, the shape restoring force of the paper that is bent even after the inclination of the paper tip is corrected moves the paper tip whose inclination is corrected in the paper transport direction and pushes it into the nip of the resist roller pair. After that, by rotating the resist roller pair to convey the paper at a predetermined timing, the paper in the state where the inclination of the tip is corrected is conveyed to the downstream side in the paper conveying direction.

According to the skew correction device disclosed in Patent Document 1, the paper is held by the transport roller pair until a predetermined timing is reached after the tip of the paper is pushed into the nip of the resist roller pair, so that the paper is bent. Remains. Since the paper is twisted due to the correction of the inclination of the paper tip side, the magnitude of the shape restoration force due to the bending differs in the paper width direction orthogonal to the paper transport direction. Therefore, in the nip of the resist roller pair that sandwiches the paper, one end side in the paper width direction in which the shape restoring force due to bending is large is more likely to slide and move than the other end side. As a result, the paper may rotate in the plane in the paper transport direction, and the tip of the paper tilts again during paper transport by the resist roller pair.
Note that this problem is not limited to the configuration in which the tip of the paper is abutted against the protruding portion of the gate member to correct the inclination of the tip of the paper, and the tip of the paper is directly abutted against the nip of the resist roller pair to correct the inclination of the tip of the paper. This is also a problem that can occur in a configuration that corrects the inclination.

In order to solve the above-mentioned problems, the present invention bends the paper by abutting the tip of the paper tilted with respect to the paper transport direction against the abutting portion before feeding the tip of the paper to the resist roller pair. In a skew correction device that corrects the inclination of the tip of the paper, the paper transport roller pair that holds the paper and transports it toward the resist roller pair and the paper transport on the upstream side in the paper transport direction from the nip of the pinch transport roller pair. The abutting member constituting the abutting portion, which is movable between the abutting position where the tip of the paper protrudes into the path and abuts the tip of the paper in the paper transport path and the retracting position where the paper is retracted from the paper transport path, and the paper When the tip of the paper is abutted against the abutting member to correct the inclination of the tip of the paper, the paper is conveyed by the sandwiching and conveying roller after the inclination of the paper tip is corrected without contacting the surface of the paper. on the surface of the the nip of the transporting pinch roller pairs abut on the upstream side in the sheet conveyance direction, and a contact means for applying a resistance force while turns with the surface movement of the sheet to the surface movement of the paper It is characterized by that.

According to the present invention, it is possible to obtain a unique effect that the tip of the paper after skew correction can be suppressed from tilting.

The schematic block diagram of the printer which concerns on this embodiment. Explanatory drawing of the control system of a printer. The schematic diagram explaining the structure of the paper transport part. The perspective view which shows the structure of the skew correction apparatus. The schematic diagram explaining the skew correction operation. The schematic diagram explaining the skew correction operation. The schematic diagram explaining the operation which suppresses the posture change of the paper after skew correction. The schematic diagram explaining the operation which suppresses the posture change of the paper after skew correction. The schematic diagram explaining the re-delivery operation of a paper in a state where the posture change of a paper is suppressed. The schematic diagram explaining the structure of the paper transport part of this modification. The cross-sectional view explaining the structure of the sheet pressing apparatus included in the paper transport part of this modification. The perspective view which shows the whole structure of the skew correction apparatus which has the paper transport part of this modification. The schematic diagram explaining the skew correction operation. The schematic diagram explaining the skew correction operation. The schematic diagram explaining the operation which suppresses the posture change of the paper after skew correction. The schematic diagram explaining the operation which suppresses the posture change of the paper after skew correction. The schematic diagram explaining the re-delivery operation of a paper in a state where the posture change of a paper is suppressed. The figure explaining the operation of projecting and separating the locking portion and the seat pressing member 2.

Hereinafter, an embodiment of an electrophotographic printer (hereinafter, simply referred to as a printer) as an image forming apparatus to which the present invention is applied will be described. First, the basic configuration of the printer 100 according to the present embodiment will be described.
FIG. 1 is an overall configuration diagram showing the printer. The printer 100 shown in FIG. 1 is a tandem type electrophotographic apparatus in an intermediate transfer method using an intermediate transfer belt 8 as an image carrier, and a paper which is a recording medium loaded and accommodated in a paper feed cassette 34 at the lower part. A paper feeding device 3 for feeding the paper is provided, and a printing mechanism unit 1 is provided above the paper feeding device 3.

The printing mechanism unit 1 is provided with a transfer device 20 provided with an endless intermediate transfer belt 8 substantially in the center, and the intermediate transfer belt 8 includes a plurality of tension rollers including a drive roller 14, driven rollers 15, 16 and the like. It is stretched by and rotates in the direction of arrow A in the figure. An intermediate transfer belt cleaning device 17 is provided on the downstream side of the driven roller 16 in the belt rotation direction, and the intermediate transfer belt cleaning device 17 removes residual toner remaining on the surface of the intermediate transfer belt 8 after image transfer. To prepare for the next image formation.

Above the linear portion of the intermediate transfer belt 8 bridged between the drive roller 14 and the driven roller 15, there are four colors, yellow, magenta, cyan, and black, along the surface movement direction of the intermediate transfer belt 8. Image forming portions 18Y, 18M, 18C, 18K are provided.

Each image forming unit 18Y, 18M, 18C, 18K is a drum-shaped photoconductor 10Y, 10M, 10C, 10K as a latent image carrier (hereinafter, when it is not necessary to explain in different colors, a color-coded code is used. Some Y, M, C, and K are omitted). Each of the photoconductors 10 is provided so as to be rotatable in the counterclockwise direction in FIG. 1, and around the photoconductor 10, a charging device 60, a developing device 61, a primary transfer roller 62 constituting a primary transfer means, and a photoconductor 10 are provided. A cleaning device 63 and a static elimination device 64 are provided, respectively. Further, an exposure device 21 is provided above the photoconductor 10.

A secondary transfer roller 22 as a transfer member constituting the secondary transfer device 104 is provided on the lower side of the intermediate transfer belt 8. The secondary transfer roller 22 is pressed against the driven roller 16 via the intermediate transfer belt 8. Then, the toner image on the intermediate transfer belt 8 is collectively transferred to the paper fed to the secondary transfer region where the secondary transfer roller 22 and the intermediate transfer belt 8 face each other. A transfer bias is applied to the driven roller 16 by the secondary transfer bias application power source in order to form a transfer electric field for transferring the toner image on the intermediate transfer belt 8 to the paper side in the secondary transfer region.

On the upstream side of the secondary transfer device 104 in the paper transport direction, there is a paper transport unit 2 which is a sheet transport device that transports the paper by matching the paper feeding timing with the image position, and the paper to be transported toward the secondary transfer device 104. A skew correction device 300 for correcting the skew of the paper is provided.

On the downstream side of the secondary transfer roller 22 in the paper transport direction, the toner image formed on the paper is fixed by heat and pressure with a fixing nip formed by pressing the pressure roller 27 against the endless fixing belt 26. A fixing device 25 is provided. The paper after image transfer is conveyed to the fixing nip of the fixing device 25 by the endless transfer belt 24 spanned between the tension roller 23a and the tension roller 23b.

Further, a jam paper purge area 80, which is a predetermined jam processing position for discharging paper when jam occurs, is provided above the transport belt 24 on the downstream side of the secondary transfer device 104. The jam paper purge area 80 is provided so that when a jam occurs, paper that is not particularly damaged is conveyed by each roller pair and automatically aggregated so that the user can easily remove the jam paper.

Next, the image forming operation in the printer of this embodiment will be described.
Based on image information from a personal computer or the like, yellow, magenta, cyan, and black monochromatic toner images are formed on each photoconductor 10. Each monochromatic toner image formed on each photoconductor 10 in this way is superimposed on the intermediate transfer belt 8 rotating in the direction of arrow A in the drawing and sequentially transferred to form a full-color composite color image. ..

On the other hand, the paper feed roller 32 in the paper feed device 3 rotates, and the paper is fed out from the paper bundle loaded and stored in the paper feed cassette 34 in the paper bank 33, separated into one sheet by the separation roller 35, and fed. It is conveyed to the paper path 36. In the printer of the present embodiment, it is possible to continuously feed out a plurality of sheets of paper from the paper feed cassette 34 for continuous printing.

The paper fed from the paper cassette 34 by the paper feed roller 32 is conveyed to the paper transfer path 70 by the transfer roller pair 37, and the paper transfer section 2 corrects the skew of the paper. After that, the paper is fed between the intermediate transfer belt 8 and the secondary transfer roller 22 by the resist roller pair 6 in accordance with the image position on the intermediate transfer belt 8.

The paper fed between the intermediate transfer belt 8 and the secondary transfer roller 22 has a color image on the paper from the intermediate transfer belt 8 due to the action of the transfer electric field due to the transfer bias applied to the secondary transfer roller 22. Transcribed. The paper on which the color image is transferred is conveyed to the fixing device 25 by the transport belt 24, heated and pressurized to fix the transferred image, and then discharged onto the paper ejection tray by the ejection roller and stacked.

The main body control unit 200 controls the operation of each unit provided in the main body of the printer 100 and the operation of the device or the like provided in each unit. The main body control unit 200 will be described with reference to FIG.

FIG. 2 is an explanatory diagram of the control system of the printer 100. As shown in FIG. 2, the main body control unit 200 includes a central processing unit (CPU) 201, a memory including a ROM 202 and a RAM 203, and I / O ports 204 and 205 for input and output. Further, the I / O port 204 is connected to the operation unit 206. The I / O port 205 includes a paper position detecting means 207, a temperature / humidity sensor 208, a photoconductor drive motor 209, a belt drive motor 210, an intermediate transfer contact / detachment clutch 211, a primary transfer high-voltage power supply 212, and a secondary transfer high-voltage power supply 213. It is connected to a charged high-voltage power supply 214, a developing high-voltage power supply 215, an LED array 216, an image position detector 217, a paper transport control means 218, a gate member drive control means 219, a pre-nip roller contact / detachment control means 220, and the like.

The paper position detecting means 207 optically detects the tip of the paper from the timing when the sandwiching and conveying roller pair and the resist roller pair start to rotate. Further, the temperature / humidity sensor 208 acquires the environmental information in the apparatus main body of the printer 100. Further, the intermediate transfer contact / detachment clutch 211 switches the trajectory of the intermediate transfer belt so that the photoconductors of the image forming units of other colors and the intermediate transfer belt are separated from each other when forming a monochrome image.

Next, the schematic configuration of the paper transport unit 2 will be described. FIG. 3 is a schematic view illustrating the configuration of the paper transport unit 2. FIG. 4 is a perspective view showing the configuration of the skew correction device.
The paper transporting unit 2 faces each other with respect to the paper transporting direction indicated by the arrow in FIG. 3 from the upstream side to the downstream side with the sheet material abutting roller pair 4 and the accompanying belt 301 of the skew correction device 300 interposed therebetween. A sandwich transfer roller pair 5 and a resist roller pair 6 composed of a gate side roller 5a as a drive roller and a delivery roller 5b as a driven roller are arranged in this order. Further, the sheet material abutting roller pair 4 and the resist roller pair 6 are composed of two rollers having substantially the same diameter facing each other across the paper transport path 70, and the sandwich transport roller pair 5 is a lower gate side roller 5a. It is composed of a pair of rollers having a diameter larger than that of the upper feeding roller 5b.

Further, the endless belt-shaped traveling belt 301, which is a resistance applying means, is stretched between a feeding roller 5b and a plenip roller 302, which is a resistance applying means. The accompanying belt 301 rotates when the gate-side roller 5a abuts on the peripheral surface of the gate-side roller 5a and rotates, or when the paper P abuts on the surface of the paper P and the paper P is conveyed. The pre-nip roller 302 is configured to be rotatable around the rotation axis of the delivery roller 5b. Then, in the ple-nip roller contact / detachment control means 220 of FIG. 2, the paper is bent on the rear end side of the paper with the retracted position where the prep-nip roller 302 retracts from the paper transport path 70 and the inclination of the paper tip corrected. Controls the movement to the resistance applying position that applies resistance to the surface of the paper. As a result, the pre-nip roller 302 is retracted from the paper transport path 70 before the inclination of the tip of the paper is corrected so that the paper transport is not hindered. After correcting the inclination of the tip of the paper, the ple-nip roller 302 intervenes a rotating belt to contact the surface of the paper to give resistance to prevent the paper from moving in the paper transport direction, thereby imparting resistance. It is possible to weaken the pushing force of the paper due to the bending of the portion on the rear end side of the paper rather than the portion.

The paper arrival detection sensor 7 which is a arrival detection means for detecting the arrival of the tip of the paper on the paper transfer path 70 at a predetermined position between the sheet material abutting roller pair 4 and the resist roller pair 6 in the paper transfer path 70. Is placed.

In the paper transport path 70 between the sheet material abutting roller pair 4 and the sandwiching transport roller pair 5, the lower transport guide 153 and a part of the extension direction facing the lower transport guide 153 are the lower transport guide. An upper transport guide 154 having a shape that bulges away from the 153 is provided. Further, the lower transport guide 153 is arranged so as to be substantially parallel to the tangential direction extending from the nip portion of the sheet material abutting roller pair 4. The bulging portion of the upper transport guide 154 is a portion where a loop (curved portion) generated when a part of the paper described later is bent is located.

The sandwiching and transporting roller pair 5 includes a gate-side roller 5a located on the lower side and a feeding roller 5b located on the upper side of the accompanying belt 301. The gate-side roller 5a is rotationally driven by a drive mechanism that is a drive means. The delivery roller 5b is rotated by a rotating belt 301 that is rotated along with the rotation of the gate side roller 5a. The peripheral length of the gate side roller 5a is longer than the distance between the sandwiching and conveying roller pair 5 and the resist roller pair 6. As a result, the corrected tip of the paper P can satisfactorily enter the nip portion of the resist roller pair without any shortage, and can be accurately transported to the target position on the downstream side in the paper transport direction with respect to the resist roller pair.

The gate-side roller 5a is provided with a gate member 9 coaxially supported adjacent to the axial end surface of the gate-side roller 5a. As shown in FIG. 3, the gate member 9 includes a fixing portion 91 of the gate member 9 fixed to the gate side roller 5a of the sandwiching transport roller pair 5 and a gate member 9 having an abutting surface 92a projecting from the paper transport path 70. It is composed of a locking portion 92 and the like, which are abutting members. Then, the fixing portion 91 and the gate side roller 5a are fastened to each other, and rotate coaxially and integrally with the gate side roller 5a.

By rotating the gate member 9, the locking portion 92 is provided so as to be movable between the abutting position where the tip of the paper abuts and the retracting position where the paper is retracted from the paper transport path 70.

The locking portion 92 is rotatably held by the gate member 9 with the shaft 93 as a fulcrum by a shaft 93 provided on the fixing portion 91. That is, the locking portion 92 has the tip of the locking portion 92 sandwiched and conveyed from the first posture in which the tip of the paper is abutted against the end surface of the fixing portion 91 of the gate member 9 with the shaft 93 as a fulcrum. It is rotatably held up to the second posture, which is housed inside the roller peripheral surface 51 of the pair 5 gate side roller 5a. Further, the locking portion 92 rotatably supported by the shaft 93 can rotate together with the fixing portion 91 together with the gate side roller 5a.

Further, the paper arrival detection sensor 7 is a sensor that detects the paper P to be conveyed downstream of the sheet material abutting roller pair 4 in the paper conveying direction. When the paper P passes through the detection location of the paper arrival detection sensor 7, it is detected that the paper P is present. Based on the detection timing, the timing at which the tip of the paper P reaches the abutting surface 92a of the locking portion 92 can be known. The position of the locking portion 92 is detected with reference to this timing. Further, based on the timing at which the tip of the paper P is detected by the paper arrival detection sensor 7, the inclination of the tip of the paper is satisfactorily corrected, and the position where the accompanying belt 301 is brought into contact with the surface of the paper to impart the above resistance. Control to move to.

The gate member 9 includes a locking portion 92 that protrudes into the paper transport path 70 in a part in the circumferential direction and is abutted when the tip of the paper abuts, and a part continuous with the locking portion 92 is on the gate side. The guide surface 94 is formed so as to follow the roller peripheral surface 51 from the inside of the roller peripheral surface 51 of the roller 5a. The guide surface 94 is configured with a low friction surface so that the tip of the paper moves while rubbing against the guide surface and exerts a function of easily guiding the tip of the paper to the nip portion of the sandwiching and conveying roller pair 5. Is preferable.

Further, as shown in FIG. 4, the delivery roller 5b facing the gate-side roller 5a is configured to be in contact with and detachable from the gate-side roller 5a. The roller widths of the gate-side roller 5a and the delivery roller 5b may be substantially the same length as each other. Since the diameter through which the tip of the locking portion 92 of the gate member 9 passes is larger than that of the gate side roller 5a, the tip of the locking portion 92 reaches the roller portion of the delivery roller 5b in the nip state of the sandwiching and transporting roller pair 5. However, since the locking portion 92 and the delivery roller 5b are arranged at positions where they do not intersect on the axis, they do not interfere with each other. As a result, the gate member 9 not only has a function of abutting the tip of the paper by the locking portion 92, but also has a function of increasing the holding width with respect to the paper by allowing the outer peripheral surface of the feeding roller 5b to come into contact with the guide surface 94. I have come to have it. At least two or more sandwiching and transporting roller pairs 5 are arranged coaxially.

Next, the skew correction operation of the paper fed from the paper feeding device 3 and the posture change suppression operation of the paper will be described. 5 and 6 are schematic views for explaining the skew correction operation, FIG. 7 is a schematic diagram for explaining the operation of suppressing the change in the posture of the paper after the skew correction, and FIG. 8 is a schematic view for explaining the posture of the paper after the skew correction. FIG. 9 is a schematic diagram illustrating an operation of suppressing a change, and FIG. 9 is a schematic diagram illustrating a paper re-transporting operation in a state of suppressing a change in the posture of the paper.

As shown in FIG. 5, the locking portion 92 of the gate member 9 is made to stand by at the abutting position protruding into the paper transport path 70, and the paper P is directed toward the sandwiched transport roller pair 5 by the sheet material abutting roller pair 4. And transport. When the paper P passes through the detection location of the paper arrival detection sensor 7, it is detected that the paper P is present, and the position of the locking portion 92 is detected based on the detection timing. As shown in FIG. 6, when the tip of the paper P abuts on the abutting surface 92a of the locking portion 92, the portion of the paper P on the rear end side of the front end of the paper P bends and deforms in a loop shape. When the feeding by the sheet material abutting roller pair 4 is continued, the surface in the paper conveying direction is eliminated by the moment centered on the tip portion of the paper P abutting on the abutting surface 92a of the locking portion 92. Rotate within. As a result, the entire tip of the paper P in the paper width direction abuts on the abutting surface 92a, so that the inclination of the paper P is corrected. The timing at which the paper P reaches the sandwiching and conveying roller pair 5 is measured by the paper arrival detection sensor 7, and in addition to the distance from the paper arrival detection sensor 7 to the position of the locking portion 92, an extra fixed distance is conveyed. The sheet material abutting roller pair 4 stops. The paper arrival detection sensor 7 guarantees a constant abutting amount against the locking portion 92. The posture of the paper is corrected by the extra distance carried.

After the inclination of the tip of the paper P is corrected in this way, the tip of the paper P is made to enter the nip portion of the pinch transfer roller pair 5, and the paper P is sent out by the pinch transfer roller pair 5 at a predetermined timing such as a writing signal. .. At this time, the amount of bending deformation differs between one end and the other end of the paper P in the paper width direction orthogonal to the paper conveying direction of the paper P. Therefore, when the paper P is fed by rotating the pinching transfer roller pair 5, the shape restoring force due to the bending applied to the tip of the paper P differs between one end side and the other end side of the paper P in the paper width direction. In the nip of the transport roller pair 5, one end side of the paper P, which has a large shape restoring force due to bending, slides more easily than the other end side. Therefore, there is a possibility that the paper is transported while being tilted to the resist roller pair 6 on the downstream side in the paper transport direction from the sandwiching and transporting roller pair 5.

According to the skew correction device 300 of the present embodiment, as shown in FIG. 6, the sheet material abutting roller pair 4 is rotated, and the number is counted after the tip of the paper P reaches the paper arrival detection sensor 7, and a predetermined value is obtained. When the count value is reached, the sheet material abutting roller pair 4 is stopped. Then, after a lapse of a certain period of time, the pre-nip roller 302 changes from the state drawn by the dotted line in FIG. 6 to the state drawn by the solid line in FIG. 6 centered on the rotation axis of the delivery roller 5b in the direction of arrow A in FIG. Rotate and move. The ple-nip roller 302 provides the paper P with a resistance force that prevents the paper from moving in the paper transport direction by the gate-side roller 5a via the accompanying belt 301. The pushing force of the paper tip due to the bending of the rear end side portion of the resistance force application portion is weakened. As a result, the magnitude of slippage in the nip of the resist roller pair is reduced as a whole, and the difference in slippage in the paper width direction is also reduced. Therefore, it is possible to prevent the tip of the paper from tilting. Further, the paper P can be brought into contact with the gate-side roller 5a on the surface by the accompanying belt 301, and the bending generated at the tip of the paper P can be satisfactorily leveled. Therefore, the magnitude of slippage in the nip of the rotating sandwiching and conveying roller pair 5 is weakened, the occurrence of rotation of the paper P in the plane is suppressed, and the tip of the paper P after skew correction is conveyed while being tilted. Can be suppressed.

As described above, by using the carrying belt 301, the surface of the paper can be brought into contact with the surface, so that the fluttering of the paper can be suppressed. Further, since a space is formed between the pre-nip roller 302 and the locking portion 92, the paper posture collapses when the paper bends. Therefore, by using the accompanying belt 301, it is possible to hold the paper while suppressing the buffer, so that the posture of the thin paper having a weak paper stiffness can be stabilized. It should be noted that the pre-nip roller 302 may be pressed by the gate-side roller 5a to generate a pressure large enough to convey the paper P without passing through the accompanying belt 301.

Then, as shown in FIG. 7, the gate member 9 rotates in the direction of arrow A in FIG. 7 so that the locking portion 92 moves from the abutting position to the retracted position. At this time, the rear end portion of the paper P is sandwiched by the sheet material abutting roller pair 4. Therefore, the paper P is bent. By further rotating the gate member 9 in the direction of arrow A in FIG. 7, the tip of the paper P is brought into the nip portion of the sandwiching and conveying roller pair 5 by the shape restoring force due to the bending of the paper P.

As shown in FIG. 8, by further rotating the gate member 9 in the direction of arrow A in FIG. 8, the locking portion 92 is retracted from the paper transport path 70 to the retracted position. The pinching transfer roller pair 5 rotates in the circumferential direction to the paper transfer start point at the same time as the locking portion 92 moves to the retracted position. The accompanying belt 301 is brought around in the direction of the arrow B in FIG. 8 by transporting the paper P while contacting the surface of the paper P. As a result, it is possible to apply a resistance force to the paper P to prevent the paper from moving in the paper transport direction, and the pushing force to the paper tip due to the bending of the rear end side portion of the resistance force application portion is weakened. Therefore, the magnitude of slippage in the nip of the rotating sandwiching and conveying roller pair 5 is weakened, the occurrence of rotation of the paper P in the plane is suppressed, and the tip of the paper P after skew correction is conveyed while being tilted. Can be suppressed. After that, the paper P is sent out at a predetermined timing such as a writing signal by the sandwiching and conveying roller pair 5.

As shown in FIG. 9, the sandwiching transfer roller pair 5 is a resist roller pair 6 that rotates and moves by a predetermined rotational movement amount starting from the paper transport start point and is always driven or driven at the same time as the holding transfer roller pair 5 is driven. Paper P is sandwiched between the nip portions. Then, the paper P is conveyed toward the secondary transfer device 104 of FIG. The locking portion 92 of the gate member 9 is projected into the paper transport path 70, and the abutting surface 92a of the locking portion 92 is positioned at the abutting position to prepare for the subsequent skew correction of the paper P.

(Modification example)
Next, a modification of the skew correction device will be described.
FIG. 10 is a schematic view illustrating the configuration of the paper transport unit 2 having the skew correction device of this modified example. FIG. 11 is a cross-sectional view illustrating the configuration of the seat pressing device 400 included in the skew correction device of this modified example. FIG. 12 is a perspective view showing the overall configuration of the skew correction device of this modified example.

As shown in FIGS. 10, 11 and 12, the sheet pressing device 400 included in the paper transport unit 2 of this modified example includes a fixing portion 401, a sheet pressing member 402, a sheet pressing member support base 403, and a sheet pressing member movement restriction. It is composed of a member 404, an elastic body 405, and a cover member 406. The fixing portion 401 is fixed on the shaft 93 of the gate-side roller 5a in the sandwiching and conveying roller pair 5, and rotates with the rotation of the gate-side roller 5a. A notch is provided in a part of the outer peripheral surface of the fixing portion 401, one end of the elastic body 405 is fixed to the bottom of the notch, and the other end is fixed to the seat pressing member support base 403. The seat pressing member 402 forms a sphere, and the elastic body 405 applies an elastic force in the direction from the center to the outer circumference of the fixing portion 401 via the seat pressing member support base 403. The sheet pressing member 402 takes the paper P around and presses against the feeding roller 5b with the belt 301 sandwiched between them. The sheet pressing member 402 is not limited to a sphere, but may be a roller.

The sheet pressing member movement restricting member 404 is provided between the side walls forming the notch, and abuts on the outer peripheral surface below the spherical apex of the sheet pressing member 402 projecting from the outer peripheral surface of the fixing portion 401. The maximum amount of protrusion from the outer peripheral surface of 402 is regulated. The cover member 406 covers the seat pressing member 402 from the outside so that the seat pressing member 402 does not protrude from the notch. The gate-side roller 5a and the seat pressing member 402 are arranged in parallel with respect to the axial direction. Further, the total length of the accompanying belt 301 and the total peripheral length of the delivery roller 5b are longer than the diameters of the gate side roller 5a and the fixing portion 401 of the seat pressing device 400. Further, the accompanying belt 301 is configured as both the gate side roller 5a and the seat pressing member 402. Further, the accompanying belt 301 or the feeding roller 5b is longer than the width including the width of the gate side roller 5a and the width of the contact portion of the sheet pressing member 402 with the paper in the axial direction of the sandwiching and conveying roller pair 5. As a result, the paper P can be stably pressed against the gate-side roller 5a and the sheet pressing member with the rotating belt 301 or the feeding roller 5b sandwiched between them.

Next, in this modification, the skew correction operation of the paper fed from the paper feeding device 3 and the posture change suppression operation of the paper will be described.
13 and 14 are schematic views for explaining the skew correction operation, FIGS. 15 and 16 are schematic views for explaining the operation of suppressing the change in the posture of the paper after the skew correction, and FIG. 17 is a schematic view for explaining the change in the posture of the paper after the skew correction. It is a schematic diagram explaining the paper re-delivery operation in the state which suppressed.

According to the skew correction device 300 of this modification, as shown in FIGS. 13 and 14, the locking portion 92 of the gate member 9 is made to stand by at the abutting position protruding into the paper transport path 70, and the paper P is placed on standby. The sheet material is conveyed toward the sandwiching and conveying roller pair 5 by the abutting roller pair 4. When the paper P passes through the detection location of the paper arrival detection sensor 7, it is detected that the paper P is present, and the position of the locking portion 92 is detected based on the detection timing. As shown in FIG. 14, when the tip of the paper P abuts on the abutting surface 92a of the locking portion 92, the paper P bends and deforms in a loop shape. When the feeding by the sheet material abutting roller pair 4 is continued, the surface in the paper conveying direction is eliminated by the moment centered on the tip portion of the paper P abutting on the abutting surface 92a of the locking portion 92. Rotate within. As a result, the entire tip of the paper P in the paper width direction abuts on the abutting surface 92a, so that the inclination of the paper P is corrected.

As shown in FIG. 15, the sheet material abutting roller pair 4 is rotated and counted after the tip of the paper P reaches the paper arrival detection sensor 7, and when a predetermined count value is reached, the sheet material abutting roller pair 4 is counted. Is stopped. Then, after a lapse of a certain period of time thereafter, the feeding roller 5b and the pre-nip roller 302 rotate the accompanying belt 301. At the same time, the gate member 9 rotates in the direction of arrow A in FIG. 15, so that the locking portion 92 moves from the abutting position to the retracting position. At this time, the rear end portion of the paper P is sandwiched by the sheet material abutting roller pair 4. Therefore, the paper P is bent. By further rotating the gate member 9 in the direction of arrow A in FIG. 15, the tip of the paper P is brought into the nip portion of the sandwiching and conveying roller pair 5 by the shape restoring force due to the bending of the paper P.

At this time, the sheet pressing member 402 of the sheet pressing device 400 rotates to a position where the maximum amount of the sheet pressing member 402 protrudes into the paper transport path 70. At the time of the maximum protrusion, it can come into contact with the accompanying belt 301. Actually, the sheet pressing member 402 and the feeding roller 5b sandwich the rotating belt 301 to grip the paper. The seat pressing member 402 receives a force perpendicular to the rotation axis of the gate side roller 5a of the sandwiching and conveying roller pair 5 by the elastic body 405 and is restrained at the maximum position. When gripping the paper, the sheet pressing member 402 is lowered to the equilibrium position of the external force because the external force is also received from the feeding roller 5b. Therefore, it is possible to stably grip the paper and satisfactorily transport the paper without applying an excessive load to the paper.

The sheet pressing member 402 abuts on the paper P and imparts a relatively weak resistance to the paper P by the interaction between the elastic force of the elastic body and the bending force of the paper P (semi-pressure contact state). When the gate member 9 further rotates, the sheet pressing member 402 presses the paper P so as to grip the paper P with the accompanying belt 301, so that the resistance force against the paper P is stronger than that in the semi-pressure contact state. Is given (total pressure welding state). When the sheet pressing member 402 is in the half pressure contact state or the full pressure contact state, a resistance force is applied to the paper P to prevent the paper P from moving in the paper transport direction. The pushing force of the paper tip due to the bending of the paper rear end side portion is weaker than that of the place where the resistance force is applied. As a result, the magnitude of slippage in the nip of the resist roller pair is reduced as a whole, and the difference in slippage in the paper width direction is also reduced. Therefore, according to this modification, the magnitude of slippage in the nip of the rotating pinch transfer roller pair 5 is weakened, the occurrence of rotation of the paper P in the plane is suppressed, and the paper P after skew correction is suppressed. It is possible to prevent the tip from being transported while tilting. Further, it is not necessary to have a mechanism for moving the accompanying belt so as to come into contact with the paper P, and a simple mechanism can prevent the tip of the paper from tilting.

Then, as shown in FIG. 16, the gate member 9 is further rotated in the direction of arrow A in FIG. 16 to retract the locking portion 92 from the paper transport path 70 to the retracted position. Simultaneously with the movement of the locking portion 92 to the retracted position, the sheet pressing member 402 presses against the accompanying belt 301 with the paper P sandwiched by the elastic force of the elastic body 405. As shown in FIG. 17, the sandwiching transfer roller pair 5 is a resist roller pair 6 that rotates and moves by a predetermined rotational movement amount starting from the paper transport start point and is always driven or driven at the same time as the holding transfer roller pair 5 is driven. Paper P is sandwiched between the nip portions. Then, the paper P is conveyed toward the secondary transfer device 104 of FIG. The locking portion 92 of the gate member 9 is projected into the paper transport path 70, and the abutting surface 92a of the locking portion 92 is positioned at the abutting position to prepare for the subsequent skew correction of the paper P.

FIG. 18 is a diagram illustrating an operation of projecting / separating the locking portion 92 and the seat pressing member 402. In FIG. 18, at time t1, the locking portion 92 protrudes from the paper transport path, and the sheet pressing member 402 is separated from the paper transport path. At the intermediate time between time t1 and time t2, the gate side roller of the pinching transfer roller pair stops, and when the paper waits for arrival at the locking portion, the locking portion 92 is in the abutting position and the sheet pressing member 402 is in the abutting position. It stands by between the protrusion and the separation (near the middle between the lower transfer guide 153 and the upper transfer guide 154 in FIG. 10) (semi-pressure contact state). Then, after the skew correction process is completed at time t2, the paper is re-conveyed. At time t3, the locking portion 92 is separated from the paper transport path, and the sheet pressing member 402 protrudes from the paper transport path and is in a full pressure contact state. Then, at time t4, the sheet pressing member 402 is separated from the paper transport path.

What has been described above is an example, and has a unique effect in each of the following aspects.
(Aspect A)
In the skew correction device 300, which corrects the inclination of the tip of the paper by bending the paper by abutting the tip of the paper tilted with respect to the paper transport direction against the abutting portion before feeding the tip of the paper to the registration roller pair. It is characterized by having a resistance applying means such as a plenip roller 302 that imparts a resistance to prevent the paper from moving in the paper transport direction with respect to the paper after the inclination of the paper tip is corrected. ..
In this embodiment, it is possible to impart a resistance force that prevents the paper from moving in the paper transport direction to the bent surface of the paper whose inclination has been corrected. Due to the resistance force, the force for pushing the leading edge of the paper in the paper transport direction is weakened by the bending of the rear end side portion of the paper rather than the portion where the resistance force is applied. As a result, the magnitude of slippage in the nip of the resist roller pair is reduced as a whole, and the difference in slippage in the paper width direction is also reduced. Therefore, it is possible to prevent the tip of the paper from tilting.

(Aspect B)
In (Aspect A), the resistance applying means is composed of a roller such as a pre-nip roller 302 that rotates with respect to the conveyed paper or an endless belt such as a traveling belt 301.
According to this aspect, the frictional force generated between the peripheral surface of the roller or the endless belt and the paper causes the force to push the paper tip in the paper transport direction due to the bending of the rear end side portion of the paper rather than the resistance applying portion. Can be weakened. Further, when an endless belt is used as the resistance applying means, the surface of the paper can be in contact with the surface of the paper on the belt surface, so that the contact area can be increased as compared with the line contact by the side in the axial direction by the roller, and the bending caused in the paper. Can be well leveled. Therefore, the force for pushing the tip of the paper in the paper transport direction is weakened by the bending of the portion on the rear end side of the portion where the resistance force is applied.

(Aspect C)
In (Aspect A) or (Aspect B), the resistance applying means provides a resistance applying position that prevents the paper from moving in the transport direction with respect to the bent surface of the tilt-corrected paper. It is characterized in that it has a structure that can be moved to a retracting position for retracting from the paper transport path.
According to this aspect, before correcting the inclination of the tip of the paper, the resistance applying means is moved to the retracted position for retracting from the paper transport path, so that the tip of the paper is improved without hindering the transport of the paper. It is struck against the abutment part. As a result, the inclination of the tip of the paper can be satisfactorily corrected. On the other hand, by moving the resistance applying means to the resistance applying position, the above resistance is applied to the surface of the paper, and the tip of the paper is pushed by the bending of the rear end side portion of the paper rather than the portion to which the resistance is applied. You can weaken your power.

(Aspect D)
In any one of (Aspect A) to (Aspect C), the paper is moved to a butt position where the tip of the paper protrudes into the paper transport path and abuts in the paper transport path, and a retracted position where the paper is retracted from the paper transport path. Of the sandwiching and transporting roller pairs 5 that sandwich and transport the paper, the paper has a butt member such as a locking portion 92 that can rotate integrally with a drive roller such as a gate-side roller 5a that applies a transporting force to the paper. It is characterized by that.
According to this aspect, by configuring the moving mechanism for moving the abutting member between the abutting position and the retracting position by a rotary motion, it becomes possible to apply it to a device requiring high productivity.

(Aspect E)
In (Aspect A) to (Aspect D), the sandwiching transport roller pair 5 for transporting the paper is provided, and the resistance applying means is corrected in inclination according to the rotation of one roller of the sandwiching transport roller pair. It can be moved to a resistance applying position that contacts the bent surface of the paper and imparts a resistance force that prevents the paper from moving in the paper transport direction, and a retracting position that retracts from the resistance applying position. It is characterized by having such a structure.
According to this aspect, the resistance applying means is brought into contact with the surface of the bending paper in response to the rotation of one of the sandwiching and transporting rollers, and the resistance that prevents the paper from moving in the paper transporting direction with respect to the paper. Power can be applied. As described above, it is possible to prevent the tip of the paper from being tilted by a simple configuration without the need for a mechanism for moving the resistance applying means.

(Aspect F)
In (Aspect E), the resistance applying means includes a paper pressing member such as a sheet pressing member 402 that presses the paper, and the paper pressing member has the resistance force in response to rotation with one roller in the sandwiching and conveying roller. It is characterized in that it moves to the imparting position and presses the paper.
According to this aspect, the resistance applying means is brought into contact with and pressed against the surface of the bending paper according to the rotation of one roller of the pair of sandwiching and conveying rollers. As a result, the paper pressing member is brought into a pressure contact state with respect to the paper to impart a resistance force that prevents the paper from moving in the paper transport direction. Therefore, it is possible to prevent the tip of the paper from tilting.

(Aspect G)
In (Aspect F), the paper pressing member is characterized in that it comes into contact with an opposing portion of the sandwiching and conveying roller that faces one of the rollers.
According to this aspect, the paper pressing member is brought into contact with the facing portion such as the feeding roller 5b and the accompanying belt 301. As a result, the paper is prevented from moving in the paper transport direction without the need for a mechanism for moving the facing portion with respect to the paper pressing member. Therefore, it is possible to prevent the tip of the paper from tilting due to the simple configuration.

(Aspect H)
In (Aspect G), the facing portion is characterized in that the axial direction of the sandwiching transport roller is longer than the width including the width of the sandwiching transport roller and the width of the contact portion of the paper pressing member with the paper. It is a thing.
According to this aspect, the facing portion can be satisfactorily pressed against the sandwiching transfer roller and the paper pressing member with the paper sandwiched between them.

(Aspect I)
In (Aspect F) to (Aspect H), the paper pressing member has a structure that is movable with respect to the rotation center of the sandwiching and conveying roller.
According to this aspect, the paper pressing member is brought into a pressure contact state with respect to the paper by a simple structure, thereby imparting a resistance force that prevents the paper from moving in the paper transport direction. Therefore, it is possible to prevent the tip of the paper from tilting.

(Aspect J)
In (Aspect I), the paper pressing member is characterized by having a restraining member that restrains the paper pressing member at a predetermined position.
According to this aspect, the paper pressing member is positioned at a position balanced with the external force with respect to the paper pressing member by restricting the movement of the paper pressing member to the paper side from the predetermined position by the restraining member. As a result, the paper can be stably gripped and the paper can be conveyed satisfactorily without giving an excessive load to the paper.

(Aspect K)
In a paper transport device having a transport means for transporting paper to a target transport position and a skew correction means for correcting the inclination of the paper transported by the transport means, the skew correction means (Aspects A) to (Aspects A) to (Aspects A). It is characterized in that any of the skew correction devices of J) is used.
According to this aspect, it is possible to provide a paper transport device capable of satisfactorily transporting paper without tilting the paper tip again after the tilt of the paper tip is corrected.

(Aspect L)
In (Aspect K), the arrival detection means such as the paper arrival detection sensor 7 that detects that the tip of the paper has reached the upstream side in the paper transport direction from the skew correction means, and the abutting member of the skew correction means. Control of the transport amount of the sheet material abutting roller pair 4 or the like that conveys the paper so as to abut the paper and the abutting roller pair such as the abutting roller pair 4 based on the trigger that the arrival detection means detects the tip of the paper. It is characterized by having a paper transport control means 218 to be executed.
If the transport amount of the butt roller pair is not set appropriately, for example, if the transport amount of the butt roller pair is smaller than the predetermined amount, the tip of the paper is not sufficiently butted against the butt member of the paper. Tilt correction is not performed well. On the other hand, if the amount of the abutting pair to be conveyed is larger than the predetermined amount, the tip of the paper is excessively abutted against the abutting member and bent, which causes a transfer failure during transportation. According to this aspect, the amount of abutting the tip of the paper against the abutting member is appropriately guaranteed by controlling the abutting roller pair to be conveyed by the conveying amount added to the distance from the arrival detection means to the abutting member. To do. As a result, the inclination of the tip of the paper can be satisfactorily corrected, and the transfer failure due to the tip of the paper being bent can be suppressed.

(Aspect M)
In (Aspect K) or (Aspect L), a plurality of the abutting members are arranged in the width direction of the paper orthogonal to the paper transport direction.
According to this aspect, in the configuration in which one abutting member is arranged in the paper width direction, an event of rotation in the plane in the paper transport direction may occur with the abutting portion as a fulcrum. Therefore, by arranging a plurality of abutting members in the paper width direction, it is possible to suppress the occurrence of an event in which the paper rotates in the plane in the paper transport direction.

(Aspect N)
In (Aspect L) or (Aspect M), based on the trigger that the tip of the paper is detected by the arrival detection means, the skew correction means is used to transport the paper to the bent surface of the tilt-corrected paper. It has a contact / detachment control means such as a prenip roller contact / detachment control means 220 that controls the movement to a position where a resistance force is applied to prevent the movement in a direction and a position away from the surface of the bent paper. It is characterized by that.
According to this aspect, the resistance resistance means is moved to the resistance applying position and the separation position based on the trigger of detecting the tip of the paper by the arrival detecting means. As a result, before correcting the inclination of the tip of the paper, the resistance applying means is retracted from the paper transport path so that the tip of the paper is satisfactorily abutted against the abutting portion without hindering the transport of the paper. The inclination of the tip of the paper can be corrected satisfactorily. On the other hand, the resistance applying means is moved to the resistance applying position, the resistance is applied to the paper by the resistance applying means, and the tip of the paper is bent due to the bending of the rear end side of the portion where the resistance is applied. The pushing force can be weakened.

(Aspect O)
In (Aspect K) to (Aspect N), the resist roller pair 6 for adjusting the trigger for transporting to the target transport position is provided, and the peripheral length of the drive roller among the pinch transport roller pairs is the same as that of the resist roller pair. It is characterized in that it is longer than the distance between the sandwiching and conveying roller pair.
According to this aspect, the corrected tip of the paper can satisfactorily enter the nip portion of the resist roller pair without any shortage, and can be accurately conveyed to the target position on the downstream side of the resist roller pair in the paper conveying direction.

(Aspect P)
In an image forming apparatus such as a printer 100 provided with an image forming means for forming an image on a recording medium and a recording medium conveying means for conveying the recording medium to the image forming means, the recording medium conveying means is (Aspect K). It is characterized in that the paper transport device according to any one of (Aspect O) is used.
According to this aspect, the recording medium can be satisfactorily conveyed to the transfer position, and image formation can be satisfactorily performed.

1 Image forming unit 2 Paper transporting unit 3 Paper feeding device 4 Sheet material abutting roller pair 5 Holding transport roller pair 5a Gate side roller 5b Feeding roller 6 Resist roller vs. 7 Paper arrival detection sensor 8 Intermediate transfer belt 9 Gate member 10 Photosensitivity Body 14 Drive roller 15 Driven roller 16 Driven roller 17 Driven roller 17 Intermediate transfer belt cleaning device 18 Image forming unit 20 Transfer device 21 Exposure device 22 Secondary transfer roller 23a Stretching roller 23b Stretching roller 24 Conveying belt 25 Fixing device 26 Fixing belt 27 Pressure roller 32 Paper feed roller 33 Paper bank 34 Paper bank 34 Separation roller 36 Paper feed path 37 Transport roller pair 51 Peripheral surface 60 Charging device 61 Developer 62 Primary transfer roller 63 Photoreceptor cleaning device 64 Static elimination device 70 Paper transport path 80 Jam Paper purge area 91 Fixed part 92 Locking part 92a Abutting surface 93 Axis 94 Guide surface 104 Secondary transfer device 153 Lower transfer guide 154 Upper transfer guide 200 Main body control unit 207 Paper position detection means 218 Paper transfer control means 219 Gate Member drive control means 220 Plenip roller contact / detachment control means 300 Skew correction device 301 Accompanying belt 302 Plenip roller 400 Seat pressing device 401 Fixed part 402 Seat pressing member 403 Seat pressing member Support base 404 Seat pressing member Movement control member 405 Elastic body 406 Cover member

Japanese Unexamined Patent Publication No. 2014-058367

Claims (17)

In a skew correction device that corrects the tilt of the tip of the paper by bending the paper by hitting the tip of the paper tilted with respect to the paper transport direction against the abutting portion before feeding the tip of the paper to the resist roller pair.
A pair of sandwiching and conveying rollers that sandwich and convey the paper toward the resist roller pair,
Between the abutting position where the tip of the paper protrudes into the paper transport path on the upstream side in the paper transport direction from the nip of the pinch transport roller pair and abuts in the paper transport path, and the retracting position where the paper is retracted from the paper transport path. A movable abutting member constituting the abutting portion and
When the tip of the paper is abutted against the abutting member to correct the inclination of the tip of the paper, the paper is not brought into contact with the surface of the paper, and after the inclination of the tip of the paper is corrected, the paper is conveyed by the sandwiching and conveying roller. on the surface of the sheet, said the nip of nip conveyance roller pairs abut on the upstream side in the sheet conveyance direction, and abutment means for imparting a resistance force while turns with the surface movement of the sheet to the surface movement of the paper A skew correction device characterized by having. In the skew correction device according to claim 1,
The abutting means is a skew correction device including a roller or an endless belt that rotates with respect to the conveyed paper. In the skew correction device according to claim 1 or 2.
The abutment means is a skew correction device having a configuration in which it can move to a contact position where it abuts on the surface of the paper whose inclination has been corrected and a retracted position where the paper is retracted from the paper transport path. In the skew correction device according to any one of claims 1 to 3,
The abutting means has a configuration that can be moved to a abutting position that abuts on the surface of the paper and a retracting position that retracts from the corresponding contact position according to the rotation of one roller of the sandwiching and conveying roller pair. A featured skew correction device. In the skew correction device according to any one of claims 1 to 4.
The abutting member is a skew correction device that can rotate integrally with a drive roller that applies a conveying force to paper among the holding and conveying roller pairs. In the skew correction device according to claim 1,
The contacting means abutting the tip of the paper against the abutting member to face the facing portion of the paper whose inclination of the tip of the paper has been corrected, and pressing the paper against the facing portion, and pressing the facing portion against the facing portion. A skew correction device comprising a paper pressing member that brings the paper into contact with the paper. In the skew correction device according to claim 6,
The paper pressing member is movable to a contact position where the facing portion is brought into contact with the paper and a retracted position retracted from the corresponding contact position according to the rotation of one roller in the sandwiching and transporting roller pair. A featured skew correction device. In the skew correction device according to claim 7,
The skew correction device is characterized in that the facing portion is longer in the axial direction of the sandwiching transport roller pair than the width including the width of the sandwiching transport roller pair and the width of the contact portion of the paper pressing member with the paper. In the skew correction device according to any one of claims 6 to 8.
The paper pressing member is a skew correction device having a structure capable of advancing and retreating so as to change the distance from the rotation center of the sandwiching and conveying roller pair. In the skew correction device according to claim 9,
A skew correction device comprising a regulating member that regulates the movement of the paper pressing member from a predetermined position, which is a predetermined distance from the center of rotation, to the paper side. In the skew correction device according to any one of claims 1 to 10.
The contacting means is a skew correction device that imparts a resistance force that prevents the paper from moving in the paper transport direction to the paper after the inclination of the paper tip is corrected. In a paper transport device having a transport means for transporting paper to a target transport position and a skew correction means for correcting the inclination of the paper transported by the transport means.
A paper transport device according to claim 1, wherein the skew correction device according to any one of claims 1 to 11 is used as the skew correction means. In a paper transport device having a transport means for transporting paper to a target transport position and a skew correction means for correcting the inclination of the paper transported by the transport means.
As the skew correction means, the skew correction device according to any one of claims 4 to 11 is used.
It has a resist roller pair that adjusts the trigger for transporting to the target transport position, and the peripheral length of the drive roller among the pinch transport roller pairs is longer than the distance between the resist roller pair and the pinch transport roller pair. A paper transport device characterized by this. In the paper transport device according to claim 12 or 13.
A pair of arrival detection means for detecting that the tip of the paper has reached upstream of the skew correction means and a butt roller pair for conveying the paper so as to abut the paper against the abutting member of the skew correction means. A paper transport device, characterized in that, the paper transport control means includes a paper transport control means that controls the transport amount of the abutting roller pair based on the trigger that the arrival detection means detects the tip of the paper. In the paper transport device according to claim 14,
A paper transport device characterized in that a plurality of the abutting members are arranged in the width direction of the paper orthogonal to the paper transport direction. In the paper transport device according to claim 14 or 15.
Based on the trigger that the tip of the paper is detected by the arrival detection means, the skew correction means is moved to the contact position where the tilt-corrected paper surface comes into contact with the paper and the distance position away from the paper surface. A paper transport device comprising a contact / separation control means for controlling. In an image forming apparatus including an image forming means for forming an image on a recording medium and a recording medium conveying means for conveying the recording medium to the image forming means.
An image forming apparatus according to any one of claims 12 to 16, wherein the paper conveying device according to any one of claims 12 to 16 is used as the recording medium conveying means.

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