JP2000247492A - Sheet carrying device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a stable transport of sheet by arranging a second interval keeping means positioned away further than a first interval keeping means with respect to at least the center of rotation of one of rotatable guide members so as to keep a distance between two guide members forming a carrying path within an allowable interval range. SOLUTION: An abutting member 20 serving as a first interval keeping means provided at a lower guide 15 in the vicinity of an inversion roller 9 on an inversion carrying path C formed by the guide 1 and a lower guide 15 is abutted against an inversion guide 1 to thereby keep an interval in the vicinity of the roller 9. Downstream of the guide 1 opposite to a second abutting member 34, a buffer member 34 is provided to make the member 34 to abut on the member 35 at the formation of the path C, and a second interval keeping means is constructed by both the members 34, 35. At the formation of the path C, the holding pressure of inversion roller pair is kept constant and the distance between the guides 1, 15 is kept to thereby surely carry a sheet of paper P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus provided with a conveying path at least one of which is formed by a rotatable guide member, and is applied to, for example, an image forming apparatus for forming an image on a sheet. Things.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus includes an image reading section for reading image information on the image surface of a book document at an upper portion, and an image forming section for forming an image on a sheet as a sheet based on the image information at a lower portion. , And a sheet deck provided at the lowermost portion thereof, to form an apparatus main body.

A sheet fed from a sheet cassette in a sheet deck at the bottom of the image forming apparatus is conveyed by a conveying roller through a predetermined guide, and is brought into contact with a certain pressure to stop at a nip of a pair of registration rollers. After that, the sheet is guided to an image forming section provided with image forming means by a pair of registration rollers which starts rotating in synchronization with the image forming operation.

The image forming section guides a light image based on image information from an image reading section or the like to a photosensitive drum to form a latent image, develops the latent image to form a toner image, and is sent. The toner image on the photosensitive drum is transferred to paper.

The sheet on which the image is formed by the image forming section passes through a conveying section, passes through a fixing section for fixing the image to the sheet, and then forms a sheet discharging section which is one of the sheet conveying units. The paper is discharged outside the apparatus through a paper discharge unit.

[0006] The discharge of the image-formed paper by the paper discharge unit includes a front-side paper discharge, which is usually performed with the image-formed side facing up, and a back-side paper discharge, which is discharged with the image-formed side reverse. You can choose to do it. The front side paper discharge guides the paper as it is and discharges it.

On the other hand, in the case of the back side discharge, the sheet immediately after being discharged from the fixing unit has the image surface on the front side. Must be on the back side. For this reason, after the paper is guided to the reverse conveyance path in the paper discharge unit by a flapper for selecting the paper discharge, the paper is reversely conveyed by a pair of reversing rollers including a reversing roller and a reversing roller at a predetermined reversing position. Then, the sheet is discharged out of the apparatus with the image forming surface on the back side.

The reversing conveyance path is formed by a reversing guide, which is a rotatable guide member having a curved surface, and a lower guide, which is a position facing the reversing guide member and is fixed to the sheet discharging unit. ing. Also, a reversing roller is provided on the lower guide, and a reversing roller is provided on the reversing guide.

[0009] There is also a setting for double-sided copying in which the sheet is once returned to the image forming section from the sheet discharging unit through the process of discharging the back side of the sheet, and the back side is also subjected to image formation and discharge.

[0010] In the case of the setting for duplex copying, the sheet forms an image on the front surface, passes through a reversing conveyance path having a pair of reversing rollers of the sheet discharging unit, is conveyed to the two-sided conveyance path, and forms an image on the back surface. After the image forming process, the sheet passes through the fixing unit and the sheet discharging unit again and is discharged outside the apparatus.

Here, the paper discharge unit is provided movably with respect to the apparatus main body so as to open the inside of the apparatus main body as a treatment for causing a paper jam in the fixing unit and the paper discharge unit.

When the paper discharge unit is moved to open the inside of the apparatus, the user grasps the handle of the paper discharge unit and releases the hook interlocking with the handle put on the apparatus main body, thereby opening the inside of the apparatus. The paper discharge unit moves.

Further, as a treatment for causing a paper jam in the reversing conveyance path, the reversing guide is configured to rotate so as to open the reversing conveyance path widely. The jammed paper can be easily removed.

The rotatable reversing guide is provided with a reversing guide pushing member for urging the reversing guide toward the lower guide, and after the processing of the jammed paper is completed, the inside of the apparatus is opened to open. The reversing guide pushing member comes into contact with the block member provided on the apparatus main body side by the moving operation of returning the sheet discharging unit to the apparatus main body, and the reversing guide and the lower guide re-form the reversing conveyance path.

A predetermined interval is maintained between the reversing guide forming the reversing conveyance path and the lower guide by the reversing guide surface abutting against a contact member provided on the lower guide near the reversing roller.

Since the position where the abutting member abuts is in the vicinity of the reversing roller, the contact pressure between the reversing roller and the reversing roller can be maintained substantially constant when the predetermined interval is maintained. , And the sheet conveyance ability in the reversing conveyance path is stabilized.

[0017]

However, in the case of the above-described prior art, the following problems have occurred.

While the abutting member abuts near the reversing roller, the reversing guide pushing member for urging the reversing guide toward the lower guide side may have a rotation center depending on the shape of the reversing guide. May be arranged at a position more distant from the abutting position where the abutting member abuts.

In this way, the reversing guide, which is pressed at a position farther from the center of rotation than the abutting position of the abutting member, is deformed toward the lower guide from the abutting position if the inverting guide itself has insufficient rigidity. In some cases, the interval between the reverse conveyance paths becomes narrow, and the paper conveyance ability may become unstable.

In order to prevent the deformation of the reversing guide, it is conceivable to add a second abutting member to the side farther from the center of rotation. It becomes difficult to maintain a state in which both the member and the conventional abutting member near the reversing roller are in contact with the reversing guide.

That is, when one of the abutting members comes into contact with the reversing guide first, there is a possibility that the other abutting member to be contacted thereafter does not abut against the reversing guide.

If the abutting member near the reversing guide is not in contact, the roller conveying force of the reversing roller pair becomes unstable, and if the reversing roller is configured to correct the curl state of the sheet, the curl correcting force is reduced. Could be reduced.

If the second abutment member farther from the center of rotation of the reversing guide is not in contact, the interval of the reversing conveyance path farther from the center of rotation of the reversing guide varies, and passes through the far side. There is a possibility that the condition of the paper to be made becomes unstable.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to maintain a constant holding pressure of a pair of conveying rollers while forming a conveying path. It is an object of the present invention to provide a sheet conveying apparatus and an image forming apparatus that secure a gap between opposed guide members over the entire length of the guide members.

[0025]

According to the present invention, there is provided a sheet conveying apparatus for forming a conveying path for conveying sheets facing each other and opening at least the conveying path. In a sheet transporting apparatus including: two guide members, one of which is rotatably provided; and a pair of transport rollers disposed to face the two guide members, respectively, to pinch and transport a sheet. A first interval maintaining means for maintaining a predetermined interval between the two guide members forming the conveying path, and a first interval maintaining means for rotating the at least one rotatable guide member.
A second interval maintaining unit that is disposed farther than the interval maintaining unit and maintains an interval within an allowable range between the two guide members that form the transport path.

Preferably, the second interval maintaining means includes a buffer means interposed between the two guide members forming the transport path.

A transport unit having the two guide members and movable with respect to the apparatus main body is provided, and at least one of the rotatable guide members is linked to an operation of moving the transport unit to the closed position. It is preferable to rotate so as to form a transport path.

The conveying roller pair is provided so as to be rotatable forward and backward,
Preferably, the sheet is switched back in the transport path.

It is preferable that the sheet enters and exits the conveying path at the center of the rotation.

An image forming apparatus according to the present invention includes the above-described sheet conveying device and image forming means for forming an image on a sheet.

Accordingly, the distance between the guide members in the vicinity of the pair of conveying rollers is kept constant to keep the clamping pressure of the pair of conveying rollers constant, and the distance between the guide members forming the conveying path facing each other is secured over the entire length of the guide member. The sheet can be stably conveyed without the sheet being jammed in the conveying path.

[0032]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The materials, shapes, relative arrangements, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

FIGS. 1 to 5 are views showing a sheet discharging unit according to the embodiment.

The paper discharging unit 2 which is a sheet conveying unit
Reference numeral 6 designates a sheet P as a sheet which can be inverted.
It is arranged downstream of the fixing section 21 of the image forming apparatus in the transport direction. Since the image forming apparatus is a known technique described in the related art, the description is omitted here.

The paper transport in the paper discharge unit 26 will be described. The paper P is discharged from the nip between the fixing roller 22 and the pressure roller 23 of the fixing unit 21 and is formed by the upper guide 4 and the reversing upper guide 5. The vehicle enters the path from the direction of arrow A.

The paper P entering from the direction A is conveyed into the paper discharge unit 26 by the internal paper discharge rollers 2 and the internal paper discharge rollers 3.

A flapper 6 is provided downstream of the inner discharge roller 2 so that the transport direction can be switched according to a paper discharge method such as front discharge or back discharge.

When the front side paper is discharged, the flapper 6 is set to 6b.
(Indicated by dotted lines in FIGS. 2 to 4), the paper P is transported along the upper guide 4 in the direction B, and is nipped and transported by the external discharge rollers 7 and the external discharge rollers 8. Paper output unit 2
From 6 is discharged out of the apparatus.

On the other hand, when the back side paper is discharged, the flapper 6
Is in the position 6a (indicated by a solid line in FIGS. 2 to 4),
Is transported to a reverse transport path C constituted by the reverse guide 1 and the lower guide 15.

The reversing guide 1 is held by guide pins 17a and 18a provided on side plates 17 and 18 on both sides in the sheet width direction, and is rotatable. Further, the reversing guide 1 includes a reversing roller 10, which presses against the reversing roller 9 provided on the lower guide 15 to generate a nip pressure and conveys the paper P passing therethrough. The sheet P conveyed to the reversing conveyance path C moves along the flapper 6 and the rotatable reversing guide 1 and is nipped and conveyed by a pair of reversing rollers including a reversing roller 9 and a reversing roller 10. The reversing roller 10 is urged toward the reversing roller 9 by a reversing roller spring, and a clamping pressure is generated between the reversing roller 9 and the reversing roller 10.

Here, the sheet P conveyed to the reverse conveying path C
When the sheet passes through the reversing guide 1, a curl following the curved shape of the reversing guide 1 tends to be formed. This curl is caused by the cooling of the heat applied to the sheet by the curl fan 12 for cooling the reversing guide 1 and the reversing. Due to the effect of stiffening the paper by the rollers 10, the shape of the reversing guide 1 is corrected in the direction opposite to the curved surface, and a flat state without curl is obtained.

Next, the sheet P conveyed to the reversing roller 9 and the reversing roller 10 is temporarily stopped at a position where the rear end of the sheet P has passed through the flapper sheet 16 and passed a certain amount, and then the reversing roller 9 By reversing the direction, the sheet is conveyed after being reversed in the conveying path D direction. Then, the sheet P transported to the transport path D
Is conveyed by being sandwiched between the external discharge rollers 7 and the external discharge rollers 8 and discharged out of the apparatus.

Here, when the paper discharge unit 26 is incorporated in the image forming apparatus, the rotation support shaft 19 and the hook 28
Has been fixed by.

The rotation support shaft 19 supports the paper discharge unit 26 in a hole in the main body side plates 29 and 30 of the apparatus main body through the side plates 17 and 18 in a rotatable state.

The hook 28 is attached to the end surface of the fixing upper stay 33 which is a component of the fixing unit 21 in the assembled state, so that the sheet discharging unit 26 cannot be separated from the apparatus main body. The hook 28 is a handle 27 that the user holds.
When the user grasps the handle 27, the hook 2
8 comes off.

Next, a paper jam process in the paper discharge unit 26 of the present embodiment will be described.

When the paper P is jammed in the reversing conveyance path C formed between the reversing guide 1 and the lower guide 15, the user grips the handle 27 as shown in FIG. 28 is removed from the upper fixing stay 33.

As a result, the paper discharge unit 26 is rotated in the direction E around the rotation support shaft 19 to open the inside of the apparatus. Thereafter, as shown in FIG. 4, the reversing guide 1 is rotated in the direction F around the guide pins 17a and 18a to separate the reversing guide 1 from the lower guide 15 to open the reversing transport path C widely, thereby reversing the reversing transport path. Paper P with paper jam in C
Get rid of.

In the paper discharging unit 26 performing the above operation, the abutting member 20 as the first interval maintaining means provided on the lower guide 15 near the reversing roller 9 contacts the reversing guide 1, and And a space near the reversing roller 9 of the reversing conveyance path C constituted by the lower guide 15 and the lower guide 15.

The urging member 20 is biased toward the lower guide 15 side of the reversing guide 1 to make contact with the reversing guide 1 by pressing the spring cap 14 provided on the reversing guide 1 with the lower stay 24 of the fixing unit 21. This is performed by pressing the reversing guide 1 in the H direction by pressing against the spring cap block member 25 provided in the above.

At this time, the spring 14a in the spring cap 14
Is compressed to generate a pressure, which is greater than the pressure of the spring 10d of the reversing roller 10 urged in the opposite direction to the spring 14a.

Therefore, regardless of the spring of the reversing roller 10, the contact between the reversing guide 1 and the lower guide 15 in the vicinity of the reversing roller pair is maintained at a predetermined distance by the abutting member 20 abutting on the reversing guide 1. 9 and reversing roller 10
Is also kept constant.

On the other hand, on the side plates 17 and 18 at both ends in the width direction of the lower guide 15 in the vicinity of the downstream side of the reversing guide 1, a second abutting member 34 is provided.

As shown in an enlarged view in FIG. 5, a buffering member 35 as a buffering means is provided on the downstream side of the reversing guide 1 facing the second abutting member 34. The second butting member 34 contacts the buffer member 35. The second abutting member 34 and the buffering member 35 constitute a second interval maintaining means.

As a result, when the spring cap 14 is pressed by the spring cap block member 25, the downstream side of the reversing guide 1 is deformed to the lower guide 15 side, and the cushioning member 35 is formed.
Abuts on the second abutting member 34, and the downstream side of the reversing conveyance path C is maintained at an interval within an allowable range.

At this time, since the reversing guide 1 and the lower guide 15 are in contact with each other via the buffer member 35, even if the reversing guide 1 is slightly deformed, the abutment member 20 is moved by the elastic deformation of the buffer member 35. There is no separation from 1 within an allowable range.

As described above, the space between the reversing guide 1 and the lower guide 15 can be maintained over the entire length of the transport path by the abutting member 20, the buffer member 35, and the second abutting member 34.

Therefore, when the reverse conveyance path C is formed,
Since the holding pressure of the pair of reversing rollers is kept constant and the interval between the reversing guide 1 and the lower guide 15 is maintained over the entire length of the transport path, the paper P can be transported stably without causing paper jam. .

The buffer member 35 may not be provided on the reversing guide 1 and may be attached to the tip of the second abutting member 34. Also, the abutment members 20, 34 are not provided on the lower guide 15,
It may be provided on the reversing guide 1, or may be provided so as to protrude from both the reversing guide 1 and the lower guide 15,
Further, the second gap maintaining means may be constituted only by the buffer member 35 without providing the second butting member 34.

The paper discharge unit 26 for opening the inside of the apparatus is not limited to the one that rotates with respect to the apparatus main body as in this embodiment, but may be one that performs a movement operation such as a slide movement.

[0061]

As described above, according to the present invention, when the two guide members form the conveyance path, the gap between the guide members near the conveyance roller pair is kept constant and the clamping pressure of the conveyance roller pair is kept constant. , The distance between the conveyance paths formed by the two guide members facing each other can be secured over the entire length of the guide members, and the sheets can be stably conveyed without the sheets being jammed in the conveyance paths. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a paper discharge unit according to an embodiment.

FIG. 2 is a cross-sectional view illustrating a sheet discharging unit according to the embodiment.

FIG. 3 is a cross-sectional view illustrating a state in which a hook of the sheet discharging unit according to the embodiment is released.

FIG. 4 is a cross-sectional view illustrating a state in which a reverse conveyance path of the sheet discharging unit according to the embodiment is opened.

FIG. 5 is a perspective view showing a second butting member and a cushioning member according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reverse guide 2 internal discharge roller 3 internal discharge roller 4 upper guide 5 reverse upper guide 6 flapper 7 external discharge roller 8 external discharge roller 9 reverse roller 10 reverse roller 12 fan 14 spring cap 15 lower guide 16 flapper sheet 17 , 18 Side plate 17a, 18a Guide pin 19 Rotating support shaft 20 Abutment member 21 Fixing part 22 Fixing roller 23 Pressure roller 24 Lower stay 25 Spring cap block member 26 Paper discharge unit 27 Handle 28 Hook 29, 30 Main body side plate 33 Fixing Upper stay 34 Second butting member 35 Buffer member

Claims (6)

[Claims] 1. A guide path which conveys a sheet facing each other, at least one of which is rotatably provided to open the inside of the feed path, and two guide members, respectively. A sheet conveying apparatus comprising: a pair of conveying rollers disposed to face each other to pinch and convey a sheet, wherein a first interval for maintaining a predetermined interval between the two guide members forming the conveying path near the pair of conveying rollers. A maintenance unit, which is disposed farther than the first interval holding unit with respect to a rotation center of the at least one rotatable guide member, and has an allowable range between the two guide members forming the transport path. And a second interval maintaining means for maintaining the sheet at an internal interval. 2. The sheet conveying apparatus according to claim 1, wherein said second interval maintaining means includes a buffering means interposed between said two guide members forming said conveying path. 3. A guide unit having the two guide members and being movable with respect to the apparatus main body, wherein the at least one guide member is rotatable in conjunction with an operation of moving the transport unit to a closed position. The sheet conveying device according to claim 1, wherein the sheet conveying device also rotates so as to form the conveying path. 4. The transport roller pair is provided so as to be rotatable forward and backward,
The sheet conveying apparatus according to claim 1, wherein the sheet is switched back in the conveying path. 5. The sheet conveying device according to claim 4, wherein the sheet is moved in and out of the conveying path on the rotation center side. 6. An image forming apparatus comprising: the sheet conveying device according to claim 1; and an image forming unit that forms an image on a sheet.