JPH11255377A - Sheet conveying device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct skewing of sheets of many sizes and thicknesses to attain stable conveying performance by providing a shutter member capable of oscillating to a first attitude of locking the leading edge of a sheet and to a second attitude, of passing a sheet. SOLUTION: In the case where a sheet with a width L1 or more skews, the sheet abuts against one of contact surfaces 12a, 12d, and then it does not abut against contact surfaces 12b, 12c of the central part. Accordingly, after it abuts against both of the contact surfaces 12a, 12d, a loop is formed to produce sliffness, thereby turing a shutter member 12 to take a second attitude. In the case where the width of a sheet is L2-L1, it abuts against only two contact surfaces 12b, 12c of the central part to form a loop, thereby turning the shutter member 12. Accordingly, in the case where the width is L2 or more, it always abuts against only two contact surfaces, thereby eliminating the possibility of turning the shutter before skewing is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for conveying a sheet in an image forming apparatus or the like, and more particularly to a sheet conveying apparatus capable of correcting a skew of a sheet and improving the sheet conveying performance. .

[0002]

2. Description of the Related Art Generally, in an image forming apparatus, an apparatus for recording an image with respect to a sheet position, that is, recording accuracy is an important image quality factor. Therefore, means for correcting skew of various sheets for improving recording accuracy has been proposed in the conventional image forming apparatus. For example, Japanese Patent Application Laid-Open No. Hei 9-83539 describes an image forming apparatus that corrects skew of a sheet using a shutter member.

An example of a conventional image forming apparatus will be described with reference to the drawings. FIG. 11 is a schematic configuration diagram of a main part of a conventional image forming apparatus.
FIG. 12 is a perspective view of a configuration around a shutter member, FIG. 13 is a schematic configuration diagram of a main part illustrating an operation of the image forming apparatus, and FIG. 14 is a diagram illustrating a state where a sheet is in contact with a shutter member.

An image forming apparatus D shown in FIG. 12 employs an electrophotographic system and employs a conventional sheet skew correcting apparatus. The image forming apparatus D emits a laser L based on the obtained information by a laser scanner, and irradiates the photosensitive drum 103 built in the process cartridge 102. As a result, a latent image is formed on the photosensitive drum 103, and is visualized by the process cartridge with toner.

On the other hand, the sheets S stacked on the sheet stacking plate 105 are separated and fed one by one by a feeding roller 106 and a separation pad 107, and further conveyed by a first conveying roller 108 and a second conveying roller 109. The toner image formed on the photosensitive drum 103 is transferred onto the conveyed sheet S by the transfer roller 104.

In the above apparatus, the second conveying roller 109 is provided so as to cover the shutter member 112.
The sheet S fed from the feeding roller 106 is skew-corrected by rotating the shutter member 112 and passing therethrough, and reaches the transfer roller 104.

Here, a configuration around the shutter member 112 and a skew correction method will be described with reference to FIG. FIG.
As shown in FIG. 2, the shutter member 112 is rotatably supported by a support shaft 114. Further, transport rollers 113a, 113b, 113c, 113d, and 113e are rotatably mounted on the support shaft 114, and are pressed against the second transport roller 109 by urging means (not shown). As a result, the transport roller 113a is driven by the rotation of the second transport roller 109, so that the transported sheet S can be nipped and transported.

The shutter member 112 has an arrow Y due to its own weight.
The stopper 112e provided integrally with the shutter member 112 abuts against the rib 115a provided on the frame 115 supporting the second transport roller 109, so that the first posture is attained. keeping. Shutter member 112
Are provided with contact surfaces 112a, 112b, 112c, and 112d. The contact surfaces 112a, 112b, 112c, and 112d extend from the downstream side in the transport direction of the second transport roller 109 onto the sheet transport surface.
And protrudes further upstream in the transport direction.

Accordingly, the sheet S transported by the first transport roller 108 is transported by the second transport roller 109 and the transport rollers 113a.
Before entering the nip formed by ｅe, the tip abuts against the contact surfaces 112a to 12d of the shutter member 112.
At this time, since the shutter member 112 has a rotational moment due to its own weight, the leading end of the sheet S is blocked,
A loop is formed as shown in FIG.

Here, when the sheet S is conveyed from the first conveying roller 108 while being skewed, the leading end of the sheet S contacts only one of the contact surfaces 112a to 12d. While forming the loop, the skew is corrected, and the other contact surfaces 112a to 12d are also contacted.

[0011] Then, by forming a loop, stiffness is generated in the sheet, and as shown in FIG.
By pressing 12d, the shutter member 112 is rotated to the second posture. As a result, the shutter member 112 retreats from the sheet conveying surface, and the sheet S can enter the nip of the second conveying roller 109.

[0012]

However, in the image forming apparatus constructed as in the above-mentioned conventional example, in order to cope with sheets of a larger size, three or more contact surfaces are provided (in FIG. (Four places). Since these contact surfaces are arranged on the same plane, the leading end of the sheet may have a plurality of contact surfaces before the skew is corrected as shown in FIG.
It comes into contact with 112c and 112d.

Then, a loop is formed in the region S1a near these contact surfaces 112c and 112d. In particular, when the sheet S is thick, the stiffness of the sheet becomes sufficiently strong and the shutter member 112 is rotated. There is. Then, in a state where the skew is not completely corrected, the second transport roller 109
The nip.

Further, in the conventional example, since the stopper 112e of the shutter member 112 is configured to abut on the frame 115 to maintain the first position, the sheet guide is provided.
A gap is formed between 116 and the contact surfaces 112a to 112d. For this reason, the leading end of the conveyed sheet S may be displaced from the contact surface, and a jam may occur.

In view of the above problems, a sheet conveying apparatus and an image forming apparatus according to the present invention provide an image forming apparatus which corrects skew and supports more stable conveying performance for sheets having a larger size and thickness. It is intended to provide a device.

[0016]

In order to solve the above-mentioned problems, a representative configuration of a sheet conveying apparatus according to the present invention includes a first conveying unit for conveying a sheet, and a sheet conveying unit for conveying a sheet more than the first conveying unit. A second transport unit that is disposed on the downstream side in the direction and transports the sheet, and a first transport unit that is disposed near the second transport unit and that abuts on the leading edge of the sheet transported by the first transport unit and locks the leading edge of the sheet. And a shutter member capable of swinging between a second position capable of passing the sheet and a shutter member, wherein the shutter member has a contact surface contacting the leading end of the sheet by a second conveying unit. Also arranged at least three places on the upstream side in the sheet conveying direction, in the direction orthogonal to the sheet conveying direction, the contact surface provided on the end portion, the contact surface on the sheet conveying direction upstream from the contact surface on the center side That you have placed And butterflies.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a sheet conveying apparatus and an image forming apparatus according to the present invention will be described with reference to the drawings. 1 is an overall configuration diagram of an image forming apparatus according to the present embodiment, FIG. 2 is a perspective view of a configuration around a shutter member, FIG. 3 is a top view of the shutter member, and FIG. FIG. The image forming apparatus A according to the present embodiment employs an electrophotographic method.

First, the overall configuration of the image forming apparatus A will be described. The image forming apparatus A emits a laser L based on the obtained information by the laser scanner 1 and irradiates the laser L onto the photosensitive drum 3 built in the process cartridge 2. As a result, a latent image is formed on the photosensitive drum 3, and the latent image is visualized by the toner by the process cartridge 2.

On the other hand, the sheets S stacked on the sheet stacking plate 5 are separated and fed one by one by a feeding roller 6 and a separation pad 7, and further conveyed downstream by a first conveying roller 8 and a second conveying roller 9. I do. On this conveyed sheet S,
The toner image formed on the photosensitive drum 3 is transferred by the transfer roller 4.

The sheet S on which the unfixed toner image has been formed is further conveyed downstream, and the fixing roller 10 applies heat and pressure to fix the toner image. Thereafter, the sheet is discharged out of the apparatus by a discharge roller 11, and an image is formed by a series of these operations.

As shown in FIG. 2, a conveying roller 13 is urged to the second conveying roller 9 by urging means (not shown), and the sheet S is nipped and conveyed by the conveying roller 13 and the second conveying roller 9. can do.

A shutter member 12 is provided downstream of the transport roller 13.
Is provided so as to cover. The shutter member 12 is rotatably supported by a support shaft 14 of the transport roller 13 and is urged in the direction of arrow X by its own weight. Shutter member
A stopper 12 e is provided integrally with the frame 12, and the stopper 12 e is attached to a frame 15 supporting the second transport roller 9.
The first posture is maintained by making contact with the rib 15a provided at the first position.

The shutter member 12 has contact surfaces 12a, 12a
b, 12c, and 12d are provided, extend from the downstream side in the transport direction of the second transport roller 9 onto the sheet transport surface, and the leading end protrudes further upstream than the second transport roller 9 in the transport direction. Therefore, the leading end of the sheet S conveyed by the first conveying roller 8 contacts the contact surfaces 12 a to 12 d of the shutter member 12 before entering the nip formed by the second conveying roller 9 and the conveying roller 13. At this time, since the shutter member 12 has a rotational moment due to its own weight, the leading end of the sheet S is blocked.

The contact surfaces 12a to 12d are, as shown in FIG.
The contact surfaces 12a and 12d on the end side are arranged so as to protrude further upstream in the transport direction than the contact surfaces 12b and 12c at the center. For this reason, if the conveyed sheet S is more than the width L1 between the contact surfaces 12a and 12d, even if the sheet S is inclined,
From contact with either one of 12a or 12d to contact with the other, it does not contact the contact surfaces 12b and 12c at the center.

Therefore, after the sheet S comes into contact with both the contact surfaces 12a and 12d, a sufficient loop is formed as shown by a solid line in FIG. 4A. As a result, stiffness occurs in the sheet S, and the shutter member 12 can be turned to the second posture as shown in FIG. 4B. Then, the sheet S reaches the nip between the second transport roller 9 and the transport roller 13 and is nipped and transported, and the image on the photosensitive drum 3 is transferred by the transfer roller 4.

Similarly, the width of the sheet S is determined by the contact surfaces 12b and 12b.
In the case where the width between c is not less than L2 and not more than L1, a loop is formed by contacting only the two center contact surfaces 12b and 12c, and the shutter member 12 is rotated.

Therefore, if the sheet has a width of L2 or more, a sheet having any width always comes into contact with only two contact surfaces. From this, it is possible to form a loop sufficient to correct the skew, and there is no possibility that the shutter is rotated before the skew is corrected.

Second Embodiment Next, a second embodiment of the sheet conveying apparatus and the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 5 is a configuration diagram of a main part of the image forming apparatus according to the present embodiment, FIG. 6 is a perspective view of a configuration around a shutter member, and FIG. 7 is a top view of the shutter member. The same parts as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 5, the image forming apparatus B employs an electrophotographic system as in the first embodiment. The shutter member 16 has four contact surfaces 16a, 16b, 16c and 16d, and in a direction orthogonal to the sheet conveying direction,
The contact surfaces 16a and 16d provided at the end portions are arranged so as to extend upstream of the center contact surfaces 16b and 16c in the sheet conveying direction.

A sheet guide 17 is provided upstream of the second transport roller 9, and forms a transport path for guiding the sheet S transported by the first transport roller 8 to the second transport roller 9. The downstream end of the sheet guide 17 is
It is arranged close to the upstream side of the second transport roller 9.

The shutter member is rotatably supported by a support shaft 14 of the transport roller 13 and is urged in the direction of arrow Y by its own weight. Then, as shown in FIGS. 5 and 6, the shutter 16 stops by contacting the contact surfaces 16 a to 16 d of the shutter member 16 with the sheet guide 17, and holds the first posture in contact with the conveyed sheet S. I have.

The sheet S conveyed from the first conveying roller 8
Is transported along the sheet guide 17. Here, since there is no gap between the sheet guide 17 and the shutter member 16,
The leading end of the sheet S surely comes into contact with the contact surfaces 16a to 16d, so that the shutter member 16 can be rotated to the second posture and pass through. Therefore, sheet jams and the like hardly occur, and stable transportability can be secured.

[Third Embodiment] Next, a third embodiment of the sheet conveying apparatus and the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 8 is a main part configuration diagram of the image forming apparatus according to the present embodiment, FIG. 9 is a perspective view of a configuration around a shutter member, and FIG. 10 is a top view of the shutter member. The same parts as those in the first or second embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

Referring to FIG. 8, an image forming apparatus C employs an electrophotographic method as in the above embodiments, and employs a sheet conveying apparatus according to the present invention. The shutter member 18 has four contact surfaces 18a, 18b, 18c and 18d, and the contact surfaces 18a and 18d provided at the end portions in the direction orthogonal to the sheet conveying direction are centered. The contact surfaces 18b and 18c are arranged so as to extend upstream in the sheet conveying direction.

A sheet guide 19 is provided upstream of the second transport roller 9. The downstream end of the sheet guide 19 is disposed close to the second transport roller 9,
The contact surfaces 18a to 18d of the shutter member 18 come into contact with the shutter member 18 to maintain the first posture.

On the other hand, at the downstream end of the sheet guide 19,
Extension portions 19a to 19h are provided on both sides of the contact surfaces 18a to 18d so as to guide the sheet to the downstream side in the conveyance direction from the contact surfaces 18a to 18d.

Therefore, the sheet S conveyed from the first conveying roller 8 is moved from the first conveying roller 8 to the second conveying roller 9 and the sheet guide 19 even after the shutter member 18 is rotated to the second posture. Guided by With such a configuration, problems such as sheet clogging can be greatly reduced, and stable transportability can be ensured.

In each of the above embodiments, an even number of contact surfaces are provided, but a wide contact surface may be provided instead of the two contact surfaces closest to the center. This is convenient for correcting skewing of narrow sheets such as business cards.

[0039]

As described above, in the sheet conveying apparatus and the image forming apparatus according to the present invention, a large loop can be formed on the upstream side of the shutter regardless of the size of the sheet. Skew can be corrected for sheets of size and thickness.

Further, by forming a loop in the sheet while the shutter member is in contact with the sheet guide,
Problems such as sheet clogging can be greatly reduced, and stable transportability can be ensured.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is a perspective view of a configuration around a shutter member.

FIG. 3 is a top view of a shutter member.

FIG. 4 is a diagram illustrating an operation of the image forming apparatus.

FIG. 5 is a main part configuration diagram of an image forming apparatus according to a second embodiment.

FIG. 6 is a perspective view of a configuration around a shutter member.

FIG. 7 is a top view of the shutter member.

FIG. 8 is a main part configuration diagram of an image forming apparatus according to a third embodiment.

FIG. 9 is a perspective view of a configuration around a shutter member.

FIG. 10 is a top view of the shutter member.

FIG. 11 is a schematic configuration diagram of a main part of an image forming apparatus according to a conventional example.

FIG. 12 is a perspective view of a configuration around a shutter member.

FIG. 13 is a schematic diagram illustrating a main part of the operation of the image forming apparatus.

FIG. 14 is a diagram illustrating a state in which a sheet is in contact with a shutter member.

[Explanation of symbols]

 L ... Laser S ... Sheet 1 ... Laser Scanner 2 ... Process Cartridge 3 ... Photosensitive Drum 4 ... Transfer Roller 5 ... Sheet Loading Plate 6 ... Supply Roller 7 ... Separation Pad 8 ... First Transport Roller 9 ... Second Transport Roller 10 ... Fixing roller 11 ... Discharge roller 12 ... Shutter member 12a to 12d ... Contact surface 12e ... Stopper 13 ... Transport roller 14 ... Support shaft 15 ... Frame 15a ... Rib 16 ... Shutter member 16a to 16d ... Contact surface 17 ... Sheet guide 18 … Shutter member 18a… Contact surface 19… Seat guide

Claims (4)

[Claims] A first conveying unit that conveys a sheet, a second conveying unit that is disposed downstream of the first conveying unit in a sheet conveying direction and conveys the sheet, and is disposed near the second conveying unit. A sheet conveying device having a shutter member swingable between a first position for abutting against a front end of a sheet conveyed by the first conveying means and locking the sheet front end and a second position for allowing the sheet to pass therethrough. In the apparatus, the shutter member has at least three contact surfaces abutting on the sheet front end in the sheet conveying direction upstream of the second conveying means, and has an end portion in a direction orthogonal to the sheet conveying direction. A sheet conveying device, wherein the contact surface provided on the side is disposed upstream of the contact surface on the center side in the sheet conveying direction. 2. The image forming apparatus according to claim 1, further comprising a guide member configured to guide a sheet conveyed by the first conveying unit to the shutter member, wherein a contact surface of the shutter member contacts the guide member. The sheet conveying device according to claim 1, wherein the sheet conveying device is configured to hold the first posture. 3. The image forming apparatus includes a guide member for guiding a sheet conveyed by the first conveying unit to the shutter member, and the guide member is provided downstream of a contact surface of the shutter member in a sheet conveying direction. The sheet conveying device according to claim 1, wherein the sheet conveying device extends to the side. 4. An image forming apparatus comprising: image recording means for recording an image on the sheet; and the sheet conveying device according to claim 1.