JP2013159438A - Sheet conveying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device configured to roughly correct skew according to a skew amount of a sheet before the front end of the sheet enters a registration member by varying a loop space according to the skew amount of the sheet, and to correct the skew with high precision by bringing a front end side following the skewed sheet into contact with the registration member with larger force.SOLUTION: A sheet conveying device includes: a registration roller pair 44 that receive a sheet S conveyed by a pre-registration roller 42 to a downstream side in a sheet conveying direction and that control the posture of the sheet; and a conveyor guide pair 43 that are provided between the pre-registration roller 42 and registration roller pair 44, and guide the front end of the sheet S conveyed to the pre-registration roller 42 to the registration roller pair 44. one conveyor guide of the conveyor guide pair 43 includes a rotary guide 43a that rotates around a center of rotation arranged at a lateral center part of the sheet S conveyed by the pre-registration roller 42 to the downstream side in the sheet conveying direction along the sheet conveying direction.

Description

  The present invention relates to a sheet conveying apparatus applied to an image forming apparatus such as a printer, a copying machine, or a facsimile.

  With regard to sheet posture control in the image forming apparatus, a sheet that is skewed greatly may be conveyed. In that case, in order to align the leading edge of the sheet and the leading edge of the image, the sheet is once stopped and the timing is adjusted. Such a general registration roller and the conveyance guide have a problem that the skew amount of the sheet cannot be eliminated.

  As a means for solving this problem, a method of adjusting the skew feeding amount by using a conveyance guide that contacts the sheet when a loop is formed on the sheet that has reached the registration roller can be considered. For example, the conveyance guide in front of the registration rollers is a guide that is divided into a plurality in the sheet width direction. The division guide is pivotally supported so as to be rotatable in a direction approaching / separating from the sheet conveyance path. As a result, means for changing the space according to the loop amount of the sheet and applying a load to the sheet has been proposed (see Patent Document 1).

Japanese Patent Laid-Open No. 9-235041

  However, in Patent Document 1, although the loop space can be made variable according to the loop amount with respect to the skew of the sheet, the skew of the sheet is not corrected before the leading edge of the sheet hits the registration roller. For this reason, it is impossible to effectively prevent the leading end of the skewed sheet from entering the nip portion when the leading end of the skewed sheet enters the nip portion of the registration roller.

  Therefore, there arises a problem that the input skew amount when the leading edge of the skewed sheet enters the nip portion of the registration roller affects the output skew amount (skew residual) after the skew correction. Further, since the division guide rotates in a direction away from the sheet conveyance path in accordance with the loop amount of the sheet, it is not possible to increase the force for abutting the trailing edge of the skewed sheet against the registration roller. Therefore, a large abutting force is generated on the leading end side of the skewed sheet, and there is a problem that an effective turning force for correcting the skew feeding is not generated.

  The present invention solves the above-described problems, and an object of the present invention is to make the loop space variable according to the amount of skew of the sheet. Furthermore, before the leading edge of the sheet enters the resist member, the skew correction can be corrected according to the skew amount of the sheet. Then, the trailing edge side of the skewed sheet can be abutted against the resist member with a larger force. This provides a sheet conveying apparatus that performs skew feeding correction with high accuracy.

  A typical configuration of the sheet conveying apparatus according to the present invention for achieving the above object includes a conveying unit that conveys a sheet, and a sheet conveyed downstream in the sheet conveying direction by the conveying unit, and has a posture thereof. A conveyance guide pair provided between the resist member to be controlled, the conveyance unit, and the registration member, and leading a leading end of the sheet conveyed to the conveyance unit to the registration member; and one of the conveyance guide pair The conveyance guide is configured to be able to rotate around a rotation center disposed along the sheet conveyance direction at an intermediate portion in the width direction of the sheet conveyed downstream in the sheet conveyance direction by the conveyance unit. It is characterized by.

  According to the above configuration, the loop space can be made variable according to the skew amount of the sheet. Furthermore, before the leading edge of the sheet enters the resist member, the skew correction can be corrected according to the skew amount of the sheet. Then, the trailing edge side of the skewed sheet can be abutted against the resist member with a larger force.

1 is an explanatory cross-sectional view illustrating a configuration of a first embodiment of an image forming apparatus including a sheet conveying device according to the present invention. (A)-(c) is a structure of 1st Embodiment of the sheet conveying apparatus which concerns on this invention, A conveyance guide rotates according to the skewing amount of this sheet | seat with advance of a sheet | seat, and loop space is variable. It is sectional explanatory drawing which shows a mode to make. FIGS. 2A and 2B show the first embodiment as viewed from the t direction in FIG. 2. As the sheet advances, the conveyance guide rotates according to the skew amount of the sheet to make the loop space variable. It is a front view which shows a mode. (A)-(c) is a structure of 2nd Embodiment of the sheet conveying apparatus which concerns on this invention, A conveyance guide is rotated according to the amount of skew feeding of this sheet | seat with advance of a sheet | seat, and loop space is variable. It is sectional explanatory drawing which shows a mode to make. FIG. 5 is a front view showing a state in which the conveyance guide rotates in accordance with the skew amount of the sheet as the sheet advances to make the loop space variable in the second embodiment viewed from the t direction in FIG. 4. (A)-(c) is a structure of 3rd Embodiment of the sheet conveying apparatus which concerns on this invention, A conveyance guide is rotated according to the skewing amount of this sheet with advancing of a sheet | seat, and loop space is variable. It is sectional explanatory drawing which shows a mode to make. It is the front view seen from the t direction of Fig.6 (a).

  An embodiment of an image forming apparatus provided with a sheet conveying apparatus according to the present invention will be specifically described with reference to the drawings.

  First, a first embodiment of an image forming apparatus provided with a sheet conveying apparatus according to the present invention will be described with reference to FIGS. FIG. 1 shows a configuration of a first embodiment of an image forming apparatus provided with a sheet conveying device 4R. In FIG. 1, an image forming unit 2 serving as an image forming unit that forms an image on a sheet S conveyed by a sheet conveying device 4 </ b> R is provided in an upper hollow portion of the image forming apparatus 1. A sheet conveying unit 4 and a sheet feeding unit 5 are provided below the image forming apparatus 1.

  In the image forming section 2, a photosensitive drum 20 as an image carrier is provided in each of the image forming stations for yellow Y, magenta M, cyan C, and black Bk. Further, a charging device 21 for uniformly charging the surface of the photosensitive drum 20 and an LED (light emitting diode) unit 22 for forming an electrostatic latent image on the photosensitive drum 20 are provided.

  Further, the image forming unit 2 includes a developing device 23 that develops the electrostatic latent image on the surface of the photosensitive drum 20 into a toner image. Further, a primary transfer roller 25 that transfers the toner image on the surface of the photosensitive drum 20 to the intermediate transfer belt 24 is provided. Further, a cleaner 26 for removing residual toner on the surface of the photosensitive drum 20 is provided.

  The intermediate transfer belt 24 is stretched around a drive roller 27, a secondary transfer inner roller 28, and a tension roller 29.

  The sheets S accommodated in the feeding cassette 501 are separated and fed one by one by the feeding roller 51 and the separation roller pair 52. Then, the plurality of conveyance rollers 53 and the conveyance roller group 41 are conveyed in the order of a pre-registration roller 42 that is a conveyance unit that conveys the sheet S and a registration roller pair 44 that is a registration member.

  The registration roller pair 44 receives the sheet S conveyed downstream in the sheet conveyance direction by the pre-registration roller 42 and controls the posture thereof. The registration member according to the present embodiment is an example configured by a registration roller pair 44 serving as a pair of conveyance rotating bodies that are pressed against each other to form a nip portion.

  The sheet S that has reached the position of the registration roller pair 44 is conveyed in synchronism with the position of the toner image on the intermediate transfer belt 24. The toner image on the intermediate transfer belt 24 is transferred onto the sheet S by the secondary transfer outer roller 45.

  A transport belt 46 that transports the sheet S and a fixing device 47 that fixes the toner image to the sheet S are provided downstream of the secondary transfer outer roller 45 in the sheet transport direction. The sheet S on which the toner image is fixed by the fixing device 47 is discharged onto the discharge tray 49 by the discharge roller 48. When printing on both sides of the sheet S, the sheet S exiting the fixing device 47 is conveyed in the order of the sheet reversing unit 6 and the double-sided conveying unit 7, and merges with the sheet conveying unit 4 again to form an image on the second surface. And is discharged onto a discharge tray 49 through a fixing device 47 and a discharge roller 48.

  2A to 2C are cross-sectional views at each position of the sheet S of the sheet conveying device 4R in the present embodiment, and FIG. 3A is a configuration diagram when FIG. 2A is viewed from the direction of the arrow t. is there. In the sheet conveying device 4R shown in FIG. 2, the locus of the leading edge S1 that precedes the sheet S when the sheet S is conveyed from the pre-registration roller 42 in a skewed state is indicated by a dotted arrow. The locus of the tip S2 is indicated by a solid arrow.

  The sheet conveyance device 4R includes a conveyance guide pair 43 that is provided between the pre-registration roller 42 and the registration roller pair 44 and guides the leading edge of the sheet S conveyed by the pre-registration roller 42 to the registration roller pair 44.

  The rotation guide 43a constitutes a part of the conveyance guide on one side of the conveyance guide pair 43. The rotation guide 43a is a rotation shaft 431 serving as a rotation center in the intermediate portion (intermediate portion in the width direction) of the sheet S conveyed in the downstream side of the sheet conveyance direction by the pre-registration roller 42. It is comprised so that it can rotate centering on. The rotation shaft 431 is disposed along the sheet conveyance direction (left-right direction in FIG. 2).

  The rotation guide 43a rotates with the leading edge of the sheet S conveyed downstream by the pre-registration roller 42 in contact with the sheet. The rotation guide 43a has a rotation shaft 431 that supports the rotation of the rotation guide 43a. Further, in the state where the rotation guide 43a is rotatably held and the sheet S is not in contact with the rotation guide 43a, as shown in FIGS. 2 (a) and 3 (a), the rotation guide 43a is maintained so as to be kept horizontal. It has compression springs 432a and 432b which are elastic members for biasing.

  As shown in FIG. 3, one end of each of the compression springs 432a and 432b has holders 433a and 433a arranged at symmetrical positions separated from each other by substantially the same distance around the rotation shaft 431 of the rotation guide 43a. It is supported by 433b. The other ends of the compression springs 432a and 432b are in contact with the surface of the rotation guide 43a at symmetrical positions separated from each other by substantially the same distance about the rotation shaft 431 of the rotation guide 43a. Configured to get.

  Each of the compression springs 432a and 432b is positioned by holders 433a and 433b provided in the apparatus main body so as to urge the rotation guide 43a with a predetermined urging force in a state of being compressed to some extent.

  Further, as shown in FIGS. 2A and 3A, when the sheet S is not touching the rotation guide 43a, the rotation shaft of the rotation guide 43a urged by the compression springs 432a and 432b. The rotation angle θ around 431 becomes zero. As such, the holders 433a and 433b are assembled with their positions adjusted.

  FIG. 2B is a cross-sectional view showing the state of the sheet conveying device 4R when the leading edge of the sheet S comes into contact with the surface of the rotation guide 43a, and FIG. 3B is an arrow t in FIG. It is the block diagram seen from the direction. The sheet S conveyed by the conveying roller group 41 of the image forming apparatus 1 shown in FIG. 1 is further conveyed downstream in the sheet conveying direction by the pre-registration roller 42 and contacts the rotation guide 43a.

  At this time, it is assumed that the sheet S is skewed. Then, as shown in FIGS. 3A and 3B, the leading end S1 of the skewed sheet S comes into contact with the rotation guide 43a. At that time, the tip S1 pushes the right side of the rotation shaft 431 of the rotation guide 43a shown in FIGS. 3 (a) and 3 (b) upward in FIGS. 3 (a) and 3 (b). The rotation guide 43a rotates about the rotation shaft 431 against the urging force of the compression spring 432a.

  At this time, as shown in FIG. 3B, the leading tip S1 that contacts and slides on the surface of the rotation guide 43a rotated about the rotation axis 431 by a predetermined rotation angle θ is It passes through a transport path longer than the leading edge S2. As a result, when the leading edge of the sheet S abuts and slides on the surface of the rotation guide 43a rotated about the rotation axis 431 by a predetermined rotation angle θ, the sheet S rotates while being roughly skewed. It is conveyed along the moving guide 43a.

  FIG. 2C is a cross-sectional view showing the state of the sheet conveying device 4R when the leading edge of the sheet S hits the nip portion of the registration roller pair 44. As described above, when the leading edge of the sheet S conveyed while coarsely correcting the skew strikes the nip portion of the registration roller pair 44, the registration roller pair 44 is stopped, so that a loop is formed on the sheet S.

  At this time, as shown in FIG. 3B, a large loop space is formed on the leading end S1 side by the rotation guide 43a that is rotated about a rotation axis 431 by a predetermined rotation angle θ. The loop space is formed small on the trailing end S2 side. Therefore, when the leading edge of the sheet S abuts against the nip portion of the registration roller pair 44, a large abutting force is generated at the trailing edge S2 where the loop space is formed to be small, and the skew of the sheet S is corrected. Sufficient turning force in the direction is generated. Thereafter, the registration roller pair 44 starts to rotate, and the sheet S whose skew has been corrected is conveyed downstream in the sheet conveying direction.

  As described above, the skew coarse correction is performed when the skewed sheet S is conveyed along the rotation guide 43a that is rotatable about the rotation shaft 431. Further, when the leading edge of the sheet S hits the nip portion of the registration roller pair 44, there is a large or small difference in the loop space formed between the leading edge S1 side and the trailing edge S2 side. Further, the skew of the sheet S can be effectively corrected by the sheet conveying device 4R by the effects of both the rough skew correction and the skew correction due to the size of the loop space.

  Next, a second embodiment of the image forming apparatus provided with the sheet conveying apparatus according to the present invention will be described with reference to FIGS. 4 and 5. In addition, what was comprised similarly to the said 1st Embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.

  In the first embodiment, when the leading edge of the skewed sheet S contacts and slides on the surface of the rotation guide 43a, the rotation guide 43a rotates about the rotation axis 431 by a predetermined rotation angle θ. It was set as the structure to do. In this case, the rotation guide 43a rotates about the rotation shaft 431 by a predetermined rotation angle θ against the urging force of the compression springs 432a and 432b by the urging force generated only by the waist force of the seat S. . In the present embodiment, the rotation guide 43a is centered on the rotation axis 431 by the rotation means based on the detection information of the skew amount detected in advance on both sides of the leading edge of the sheet S upstream of the rotation guide 43a in the sheet conveyance direction. Is configured to rotate by a predetermined rotation angle θ.

  4A to 4C are cross-sectional views at each position of the sheet S of the sheet conveying device 4R in the present embodiment, and FIG. 5 is a configuration diagram viewed from the direction of the arrow t in FIG. The sheet conveying apparatus 4R according to the present embodiment includes a sensor array 8 serving as a plurality of leading edge detecting means for detecting both sides of the leading edge of the sheet S conveyed downstream in the sheet conveying direction by the pre-registration roller 42. The sensor array 8 is disposed upstream of the rotation guide 43a in the sheet conveying direction.

  The present embodiment further includes a gear train 430 that serves as a turning means for turning the turning guide 43a about the turning shaft 431, and a motor 9 that rotationally drives the gear row 430.

  Furthermore, the motor 9 is rotationally driven by the control unit 10 serving as control means based on the detection information obtained by detecting the both sides of the leading edge of the sheet S by the sensor array 8. Then, the gear provided on the rotation shaft 431 of the rotation guide 43a is rotated through the gear train 430 connected to the rotation shaft of the motor 9. Then, the control unit 10 controls the rotation angle θ about the rotation shaft 431 of the rotation guide 43a.

  The control unit 10 detects both sides of the leading edge of the sheet S by the sensor array 8. Based on the detected detection information, the rotation shaft 431 of the rotation guide 43a is moved before the leading edge of the sheet S conveyed downstream in the sheet conveyance direction by the pre-registration roller 42 hits the nip portion of the registration roller pair 44. The rotation angle θ as the center is controlled.

  The sensor row 8 is configured to have two or more optical sensors on the front side and the back side in FIG. 4 so that the skew amount of the sheet S can be detected. 4A to 4C show the locus of the leading edge S1 that precedes the sheet S when the sheet S is conveyed from the pre-registration roller 42 in a skewed state, and the trailing edge that follows the sheet S. S2 is indicated by a solid arrow.

  The position of the sheet S conveyed by the pre-registration roller 42 is detected by the sensor array 8 disposed immediately downstream of the pre-registration roller 42 in the sheet conveyance direction, and the control unit 10 detects the position of the sheet S. The amount of skew is calculated. After that, as shown in FIG. 5, the control unit 10 drives the motor 9 so that the rotation angle θ about the rotation axis 431 of the rotation guide 43a matches the skew amount of the sheet S, and the gear train. A rotational driving force is applied to the rotation shaft 431 via 430 to change the posture of the rotation guide 43a.

  FIG. 4B is a cross-sectional view illustrating a state of the sheet conveying device 4R when the leading edge of the sheet S comes into contact with the rotation guide 43a. The sheet S conveyed by the pre-registration roller 42 corresponds to the skew amount of the sheet S detected by the sensor row 8 and is on the surface of the rotation guide 43a already rotated by a predetermined rotation angle θ. Contact.

  Here, as in the first embodiment, the leading end S1 of the skewed sheet S that contacts and slides on the surface of the rotation guide 43a rotated by a predetermined rotation angle θ is It passes through a transport path longer than the leading edge S2. As a result, the sheet S is conveyed along the surface of the rotation guide 43a that has been rotated by a predetermined rotation angle θ while coarsely correcting skew.

  FIG. 4C is a cross-sectional view illustrating the state of the sheet conveying device 4 </ b> R when the leading edge of the sheet S hits the nip portion of the registration roller pair 44. Similar to the first embodiment described above, the leading edge of the sheet S conveyed while roughly correcting the skew along the surface of the rotation guide 43a rotated by a predetermined rotation angle θ is the registration roller pair 44. It hits the nip. At this time, since the registration roller pair 44 is stopped, a loop is formed on the sheet S.

  At this time, a large loop space formed on the leading end S1 side of the sheet S formed along the surface of the rotation guide 43a rotated by a predetermined rotation angle θ, and the trailing end S2 side There is a large or small difference from the small loop space formed in Due to the difference in the size of the loop space, a large abutting force is generated on the trailing edge S2 side following the sheet S, and a sufficient turning force is generated in the direction in which the skew is corrected in the sheet S.

  Thereafter, the rotational driving of the registration roller pair 44 is started, and the sheet S whose skew has been corrected is further conveyed downstream in the sheet conveying direction.

  As described above, the skew coarse correction when the skewed sheet S is conveyed along the rotation guide 43a and the skew due to the difference in the loop space when the sheet S hits the nip portion of the registration roller pair 44. Both effects of correction can be obtained. Thus, effective skew correction can be performed as in the first embodiment.

  Further, since the rotation angle θ around the rotation axis 431 of the rotation guide 43a is controlled by the control unit 10, the skew correction of the sheet S can be corrected with higher accuracy than in the first embodiment. Other configurations are the same as those in the first embodiment, and the same effects can be obtained.

  Next, a third embodiment of the image forming apparatus provided with the sheet conveying apparatus according to the present invention will be described with reference to FIGS. 6 and 7. In addition, what was comprised similarly to each said embodiment attaches | subjects the same code | symbol, and abbreviate | omits description.

  In each of the above-described embodiments, the registration roller pair 44 serving as a pair of transport rotating bodies is configured as an example of the registration member. In this embodiment, as shown in FIGS. 6 and 7, as another example of the resist member, a resist shutter 441 serving as a sheet contact member is provided. The registration shutter 441 is held at a position where it abuts against the leading edge of the sheet S conveyed downstream in the sheet conveyance direction by the pre-registration roller 42 and prevents the sheet S from proceeding. And it is comprised so that it can move from the position to the position which cancels prevention of advance of sheet S.

  6A to 6C are cross-sectional views at each position of the sheet S of the sheet conveying apparatus 4R in the present embodiment. In this embodiment, instead of the registration roller pair 44 in each of the above embodiments, a registration shutter 441 as a registration member and a conveying roller pair 442 in a state of being always driven to rotate are combined. The registration shutter 441 is pivotally supported by the rotation shaft of one roller 442a of the conveyance roller pair 442 in a state where the wall surface portion 441a as a sheet contact member is positioned upstream of the nip portion of the conveyance roller pair 442 in the sheet conveyance direction. ing.

  Then, an urging means (not shown) is attached in the direction opposite to the arrow q direction in FIG. 6 (c) so as to be rotatable around the rotation axis of one roller 442a (in the arrow q direction in FIG. 6 (c)). 6 and is held in a state shown in FIGS. 6A and 6B by a stopper (not shown).

  As shown in FIG. 6B, the leading edge of the sheet S conveyed by the pre-registration roller 42 and conveyed while roughly correcting the skew by the rotation guide 43a contacts the wall surface portion 441a of the registration shutter 441. Then, as described above in each of the embodiments, a large abutting force is generated on the trailing edge S2 side of the skewed sheet S, and a turning force in a direction in which the skew is corrected is generated on the sheet S. To do.

  The sheet S that has been skew-corrected by the above operation is further given a conveying force by the pre-registration roller 42. Then, the resist shutter 441 with which the leading edge of the sheet S abuts according to the strength of the sheet S is rotated in the direction of the arrow q in FIG. The wall surface portion 441a of 441 is retracted from the sheet conveyance path. The sheet S is always sandwiched between the pair of conveying rollers 442 in a rotationally driven state, and further conveyed downstream in the sheet conveying direction.

  The configuration other than the registration shutter 441 and the conveyance roller pair 442 can be configured in the same manner as in each of the above embodiments, and the same effect can be obtained. In the present embodiment, by using the registration shutter 441 and the conveying roller pair 442, the same effect as in each of the above embodiments can be obtained, and the skew remaining due to the leading edge of the sheet S being stuck in the nip portion of the registration roller pair 44. Can be realized. In general, the registration roller pair 44 is configured to apply pressure at both ends of the rotation shaft, so that the pressing force at the central portion in the axial direction tends to decrease. It is possible to realize a sheet conveying device 4R capable of correcting skew feeding.

S ... Sheet
42 ... Roller before registration (conveying means)
43a ... Rotating guide (one conveyance guide)
44… Registration roller pair (registration member; a pair of conveying rotating bodies)

Claims (7)

Conveying means for conveying the sheet;
A resist member that receives the sheet conveyed downstream in the sheet conveying direction by the conveying means and controls its posture;
A pair of conveyance guides provided between the conveyance unit and the resist member and guiding a leading edge of the sheet conveyed to the conveyance unit to the registration member;
One conveyance guide of the pair of conveyance guides rotates around a rotation center arranged along the sheet conveyance direction at an intermediate portion in the width direction of the sheet conveyed downstream by the conveyance unit in the sheet conveyance direction. A sheet conveying apparatus configured to be obtained.   The sheet conveying apparatus according to claim 1, further comprising an elastic member that rotatably holds the one conveyance guide. A plurality of leading edge detecting means for detecting the leading edge of the sheet conveyed downstream in the sheet conveying direction by the conveying means;
Rotation means for rotating the one conveyance guide around the rotation center;
Control means for driving the turning means on the basis of detection information of the tip detecting means to control the turning angle of the one conveyance guide;
The sheet conveying apparatus according to claim 1, further comprising: The leading edge detection unit is disposed on the upstream side in the sheet conveyance direction from the one conveyance guide,
Based on the detection information of the leading edge detecting means, the control means determines the rotation angle of the one conveying guide before the leading edge of the sheet conveyed by the conveying means on the downstream side in the sheet conveying direction hits the registration member. The sheet conveying device according to claim 3, wherein the sheet conveying device is controlled.   5. The sheet conveying apparatus according to claim 1, wherein the resist member includes a pair of conveying rotating body pairs.   The resist member is movable to a position where the sheet is conveyed to the downstream side in the sheet conveying direction by the conveying means to prevent the sheet from advancing and to a position where the sheet is prevented from advancing. The sheet conveying apparatus according to claim 1, comprising a sheet contact member. The sheet conveying apparatus according to any one of claims 1 to 6,
Image forming means for forming an image on the sheet conveyed by the sheet conveying device;
An image forming apparatus comprising:

Images