JP5482127B2 - Paper conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus, particularly an image forming apparatus such as a copying machine or a printer, a document reading apparatus attached to the image forming apparatus, or a sheet incorporated in a sheet post-processing apparatus having a function of binding sheets. The present invention relates to a conveyance device and an image forming apparatus including the sheet conveyance device.

  In general, in an image forming apparatus that forms an image on a sheet by an electrophotographic process, conveyance of the sheet is performed by guiding the sheet in a specific direction by a guide member while applying a driving force in one direction to the sheet by a roller pair. ing. Due to the layout inside the apparatus, a curved portion always exists in the paper conveyance path, and the paper is guided in a predetermined direction by the guide member in the curved portion.

  Therefore, if a curved portion exists on the downstream side in the conveyance direction of the roller pair, the paper is already curved by the guide member when the trailing edge of the paper conveyed by the roller pair passes through the roller pair. Since the rear edge of the sheet bounces toward the outer guide member and momentarily strikes the guide member, an unpleasant collision sound is generated.

  Therefore, in Patent Documents 1 and 2, a leaf spring or an elastic member is provided on the downstream side of the pair of rollers in order to prevent the rear edge of the paper in the reverse path path curved in a U-shape. A paper transport device has been proposed.

  Certainly, in the paper conveyance devices described in Patent Documents 1 and 2, it is possible to suppress the collision noise caused by the trailing edge of the paper. However, a collision sound is generated even when the leading edge of the paper enters the roller pair, and it has not been solved in the past to suppress this collision sound.

Japanese Patent Application Laid-Open No. 11-246073 JP 2002-68512 A

  Accordingly, an object of the present invention is to prevent a collision sound when the leading edge of the conveyed paper enters the roller pair and a collision noise to the guide member that occurs when the trailing edge of the paper leaves the roller pair. It is an object of the present invention to provide a sheet conveying apparatus and an image forming apparatus that can perform the above.

In order to achieve the above object, a sheet conveying apparatus according to a first embodiment of the present invention is
A guide member for curving and guiding the conveyed paper;
An upstream roller pair and a downstream roller pair that convey the paper in one direction along a conveyance path formed by the guide member;
An elastic member provided near the upstream roller pair and provided on the guide member;
With
The upstream roller pair is disposed at a position where the sheet is conveyed at the curved portion,
The downstream roller pair is disposed at a position for receiving a sheet having undergone a curved portion,
The elastic member has an upstream end and a downstream end extending upstream and downstream from the intersection of the tangent of the nip portion of the upstream roller pair and the guide member, and a sheet conveyance path. It is arranged at the width direction center part and the width direction both ends ,
The rigidity of the elastic member arranged at both ends in the width direction of the paper transport path is smaller than the rigidity of the elastic member arranged at the center part in the width direction;
It is characterized by.
The sheet conveying apparatus according to the second aspect of the present invention is
A guide member for curving and guiding the conveyed paper;
An upstream roller pair and a downstream roller pair that convey the paper in one direction along a conveyance path formed by the guide member;
An elastic member provided near the upstream roller pair and provided on the guide member;
With
The upstream roller pair is disposed at a position where the sheet is conveyed at the curved portion,
The downstream roller pair is disposed at a position for receiving a sheet having undergone a curved portion,
The elastic member has an upstream end and a downstream end extending upstream and downstream from the intersection of the tangent of the nip portion of the upstream roller pair and the guide member,
The elastic member has a rigidity on the downstream side of the pair of upstream rollers larger than a rigidity on the upstream side,
It is characterized by.

An image forming apparatus according to a third aspect of the present invention includes the sheet conveying device.

  In the paper transport device, the elastic members extending upstream and downstream in the transport direction of the roller pair are cushioning materials for the leading edge of the paper that is about to enter the roller pair and the trailing edge of the paper that has slipped out of the roller pair. And the collision noise at the leading and trailing edges of the paper is suppressed.

  According to the present invention, it is possible to effectively prevent a collision sound when the leading edge of the conveyed paper enters the roller pair and a collision sound with the guide member that occurs when the trailing edge of the paper leaves the roller pair. be able to.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus. 1 shows a sheet conveying apparatus according to a first embodiment, where (A) is a cross-sectional view and (B) is a perspective view. In the paper conveying apparatus which is 1st Example, when a paper rushes into a roller pair is shown, (A) is sectional drawing, (B) is a perspective view. In the paper conveying apparatus which is 1st Example, it shows when a paper slips out of a roller pair, (A) is sectional drawing, (B) is a perspective view. It is a perspective view which shows the paper conveying apparatus which is 2nd Example. It is a perspective view which shows the paper conveying apparatus which is 3rd Example. It is a perspective view which shows the paper conveying apparatus which is 4th Example. It is sectional drawing which shows the paper conveying apparatus which is 4th Example. It is sectional drawing which shows the paper conveying apparatus which is 5th Example.

  Hereinafter, embodiments of a sheet conveying device and an image forming apparatus according to the present invention will be described with reference to the accompanying drawings. In the drawings showing the respective embodiments, the same members and portions are denoted by the same reference numerals, and redundant description is omitted.

(Schematic configuration of image forming apparatus, see FIG. 1)
The image forming apparatus shown in FIG. 1 is a color printer using a tandem electrophotographic method, and is roughly a process unit 10 (10Y, 10M, 10) for forming toner images of each color of Y, M, C, K. 10C, 10K), an intermediate transfer unit 20, a three-stage sheet feeding unit 30 containing recording paper, and a fixing unit 35.

  Each process unit 10 includes a photosensitive drum 11, a charging charger 12, an exposure device 13, a developing device 14, a cleaning device 15 for the photosensitive drum 11, and the like. The electrostatic latent image drawn on the photosensitive drum 11 is developed by the developing unit 14 to form toner images of each color.

  The intermediate transfer unit 20 includes an intermediate transfer belt 21 that is rotationally driven endlessly in the direction of the arrow Z, and each photoconductor drum 11 is subjected to an electric field applied from a primary transfer roller 22 facing each photoconductor drum 11. The toner image formed above is primarily transferred onto the intermediate transfer belt 21 to be synthesized. Note that such an electrophotographic image forming process is well known, and a detailed description thereof will be omitted.

  In the lower part of the apparatus main body, paper feed units 30 for feeding stacked paper one by one are arranged in three stages, and the paper is selectively fed from each paper feed unit 30 with a paper feed roller 31 and a separating roller 32. Is conveyed to the nip portion between the intermediate transfer belt 21 and the secondary transfer roller 25 through the timing roller pair 33, where the toner image (synthesized color image) is secondarily transferred. Thereafter, the sheet is conveyed to the fixing unit 35 where the toner is heated and fixed, and is discharged to the tray portion 5 disposed on the upper surface of the apparatus main body.

  By the way, the sheet conveying apparatus according to the present invention is disposed, for example, at a location where the timing roller pair 33 is installed (a location indicated by a symbol A in FIG. 1), and will be described as a first embodiment to a fifth embodiment below.

(Refer to the first embodiment, FIGS. 2, 3, and 4)
As shown in FIG. 2A, the sheet conveying apparatus according to the first embodiment has a roller pair 33 that conveys a sheet in one direction (arrow B direction) and a downstream side in the conveying direction B by the roller pair 33. The pair of rollers 34 is arranged, guide members 41 and 42 for curving and guiding the conveyed paper, and an elastic member 45 provided on the inner surface of the outer guide member 42. The roller pair 33 is disposed at a position for conveying the sheet at the curved portion, and the roller pair 34 is disposed at a position for receiving the sheet that has passed through the curved portion.

  As shown in FIG. 2B, the roller pair 33 is divided into two pairs of rollers, and the guide members 41 and 42 are installed over the entire width of the sheet conveyance path. The elastic member 45 is disposed between the roller pair 33 at the center in the width direction of the paper transport path. The guide members 41 and 42 are made of a rigid body of metal or resin, and form a curved conveyance path that guides the sheet that has passed through the roller pair 33 upward by approximately 60 ° from the horizontal direction. In this case, the outer guide member 42 functions to bend and guide the sheet, and the inner guide member 41 functions to correct the sheet conveyance direction.

  The elastic member 45 is made of a resin film or a thin spring-like metal plate, and the upstream end 45a in the conveying direction B goes around the opening from the opening 42a of the guide member 42 and sticks to the outer surface of the guide member 42. Has been. The downstream end 45 b of the elastic member 45 in the transport direction B is attached to the inner surface of the guide member 42. The downstream end 45b is not necessarily attached to the guide member 42, and may simply be in contact with the inner surface of the guide member 42. When the tangent of the nip portion of the roller pair 33 is C, the upstream end 45a of the elastic member 45 extends upstream from the intersection C1 between the tangent C and the guide member 42. The downstream end 45 b extends further downstream than the intersection C <b> 2 between the tangent line C and the guide member 42.

  In the above configuration, as shown in FIG. 3, when the paper P is conveyed in the direction of arrow B, the leading edge of the paper P contacts the elastic member 45 immediately before colliding with the roller pair 33, and the elastic member 45 It rushes into the roller pair 33 in a buffered and guided state. Therefore, the collision noise when the leading edge of the paper P enters the roller pair 33 is suppressed. Further, as shown in FIG. 4, the paper P is held in the roller pair 34 on the downstream side and conveyed in the direction of arrow B, and when the rear end of the paper P passes through the roller pair 33, Can be flipped toward the outer guide member 42. At this time, the movement of the trailing edge of the paper P is buffered by the elastic member 45 and does not collide with the guide member 42, thereby preventing the occurrence of a collision sound. The rigidity of the elastic member 45 can be set to an arbitrary value within a range in which the sheet collision noise can be suppressed.

(Refer to the second embodiment, FIG. 5)
As shown in FIG. 5, the sheet conveying apparatus according to the second embodiment is configured such that the elastic members 45 are arranged at the center portion in the width direction and both end portions in the width direction of the sheet conveying path, and the guide members 42 of these elastic members 45. The mounting form is the same as in the first embodiment. Therefore, the operational effects of the second embodiment are the same as those of the first embodiment.

  In the second embodiment, it is desirable that the rigidity of the elastic member 45 arranged at both ends in the width direction is smaller than the rigidity of the elastic member 45 arranged at the center part in the width direction. This is because both ends of the sheet in the width direction correspond to the fact that the collision force is smaller than that of the center part, and the conveyance of the sheet is not impaired as much as possible.

(Refer to the third embodiment, FIG. 6)
As shown in FIG. 6, the sheet conveying apparatus according to the third embodiment has elastic members 45 arranged at both end portions in the width direction in the sheet conveying direction. The elastic member 45 is attached to the guide member 42 in the above-described manner. This is the same as in the first embodiment. Accordingly, the operational effects of the third embodiment are the same as those of the first embodiment.

(Refer to the fourth embodiment, FIGS. 7 and 8)
By the way, in the paper conveying apparatus, the elastic member 45 may have different rigidity on the upstream side and the downstream side of the dotted line D located in the vicinity of the roller pair 33 as shown in FIG. In this case, it is preferable that the rigidity on the downstream side of the dotted line D is larger than the rigidity on the upstream side.

  Specifically, as shown in FIG. 8, one resin film or a thin metal plate 46 can be laminated on the downstream side rear surface of the elastic member 45 to increase the rigidity. Alternatively, the rigidity may be increased by making the downstream side of the elastic member 45 thicker than the upstream side.

(Refer to the fifth embodiment, FIG. 9)
As shown in FIG. 9, the paper conveying apparatus according to the fifth embodiment is provided with an elastic member 47 made of sponge or foam material inside the elastic member 45, and the elastic member 47 is arranged on the inner surface of the guide member 42. The elastic member 45 is attached with a small gap. The elastic member 47 may be disposed without a gap with respect to the elastic member 45. By providing another elastic member 47, the rigidity of the elastic member 45 can be reinforced.

(Other examples)
The sheet conveying device and the image forming apparatus according to the present invention are not limited to the above-described embodiments, and can be variously modified within the scope of the gist.

  For example, the sheet conveying apparatus according to the present invention can be provided at a location other than the location indicated by the symbol A in FIG. Further, the configuration and shape of the guide member and the elastic member are arbitrary. Further, the image forming apparatus to which the present invention is applied may be a copying machine, a facsimile, a complex machine of these, or a monochrome image forming apparatus in addition to the tandem electrophotographic printer. Furthermore, the paper transport device according to the present invention can be mounted on a paper post-processing device such as a scanner for reading a document image or a finisher having a function of binding paper.

  As described above, the present invention is useful for a sheet conveying apparatus and an image forming apparatus. In particular, the collision sound when the leading edge of a sheet to be conveyed enters a roller pair, and the trailing edge of the sheet is a roller pair. It is excellent in that it can prevent a collision sound to the guide member that occurs when it comes off.

33 ... upstream roller pair 34 ... downstream roller pair 42 ... guide member 45 ... elastic member 45a ... upstream end 45b ... downstream end C ... tangent C1, C2 ... intersection

Claims (8)

A guide member for curving and guiding the conveyed paper;
An upstream roller pair and a downstream roller pair that convey the paper in one direction along a conveyance path formed by the guide member;
An elastic member provided near the upstream roller pair and provided on the guide member;
With
The upstream roller pair is disposed at a position where the sheet is conveyed at the curved portion,
The downstream roller pair is disposed at a position for receiving a sheet having undergone a curved portion,
The elastic member has an upstream end and a downstream end extending upstream and downstream from the intersection of the tangent of the nip portion of the upstream roller pair and the guide member, and a sheet conveyance path. It is arranged at the width direction center part and the width direction both ends ,
The rigidity of the elastic member arranged at both ends in the width direction of the paper transport path is smaller than the rigidity of the elastic member arranged at the center part in the width direction;
A paper conveying device characterized by the above. The paper conveying apparatus according to claim 1, wherein the elastic member has different rigidity between an upstream side and a downstream side of the upstream roller pair. A guide member for curving and guiding the conveyed paper;
An upstream roller pair and a downstream roller pair that convey the paper in one direction along a conveyance path formed by the guide member;
An elastic member provided near the upstream roller pair and provided on the guide member;
With
The upstream roller pair is disposed at a position where the sheet is conveyed at the curved portion,
The downstream roller pair is disposed at a position for receiving a sheet having undergone a curved portion,
The elastic member has an upstream end and a downstream end extending upstream and downstream from the intersection of the tangent of the nip portion of the upstream roller pair and the guide member,
The elastic member has a rigidity on the downstream side of the pair of upstream rollers larger than a rigidity on the upstream side,
Paper transport device for you characterized. The paper conveying apparatus according to claim 3, wherein the elastic member is arranged at a central portion in the width direction and / or at both ends in the width direction of the paper conveying path. The elastic member, the sheet conveying device according to any one of claims 1 to 4, characterized in that it consists of a resin film or sheet metal. Any the upstream end of the elastic member is disposed on the outer surface of the guide member, the downstream end of claims 1 to 5, characterized in, that it is arranged on the inner surface of said guide member sheet conveying apparatus according to any. Sheet conveying apparatus according to any one of claims 1 to 6, characterized in that, provided with good enough for the elastic member to the inside of the elastic member. An image forming apparatus comprising the sheet conveying device according to any one of claims 1 to 7.

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