JP2008081286A - Paper delivery device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper delivery device, almost eliminating limitation on the kind of paper used without any increase in height even in a curl straightening device and image forming apparatus. <P>SOLUTION: An angle of entering a nip formed between a paper delivery roller 21 and a curl straightening roller 22 on the upstream side in the paper transport direction is obliquely declined, the paper delivery roller 21 is constructed as a belt holding roller round which a belt 31 for guiding paper P toward the nip is wrapped, and the belt 31 is wrapped round a pulley 32 disposed on the upstream from the paper delivery roller 21 in the paper transport direction. In the belt 31, a traveling side traveling from the pulley 32 toward the paper delivery roller 21 is formed as a belt 31a for guiding the paper, and the angle θ1 of inclination of the belt 31a is substantially equal to the angle of entering the nip. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a paper discharge device and an image forming apparatus.

  In an image forming apparatus that executes an electrophotographic copying process such as a copying machine, a printer, or a facsimile machine, an electrostatic latent image formed on an image carrier is subjected to a visible image processing in a developing process, and then the visible image is processed. Electrostatic transfer is performed on recording paper (hereinafter referred to as paper), which is one of recording media, and the transferred visible image is obtained, for example, by heating and fixing as a copy or a recorded material. . The paper is discharged by the paper discharge device toward the paper discharge unit after fixing, but most of the paper discharge devices are composed of a pair of rollers. With this configuration, when the paper is curled, the leading edge of the paper that has passed through the paper discharge roller advances in the direction in which the paper is curled, and collides with the paper discharge tray surface, thereby smoothing the paper. There is a case where the paper cannot be discharged onto the paper discharge tray and is jammed, so-called jam occurs.

  One of the causes of the curling is the distance between the fixing device and the contact position between the paper discharge rollers. This distance is one of the factors that determine the size of the image forming apparatus. If the distance is increased, the height of the image forming apparatus increases. For this reason, when the distance is shortened, the conveyance path of the paper fed out from the fixing device may be bent suddenly, and this causes the sheet S to be easily bent or so-called curled.

JP 2002-145507 A

  In order to eliminate the curl generated in such a sheet, as shown in Patent Document 1, a paper discharge device including a pair of curl correction rollers has been proposed along the peripheral surface of the discharge roller. In the paper discharge device 100, as shown in FIG. 5, the paper P moves along the circumferential direction of the discharge roller 101 and is folded back in the direction opposite to the direction of curling by the pair of curl correction rollers 102 and 103. It goes out with the curl corrected.

  By the way, in the apparatus that discharges paper after the paper transport path has been bent sharply after passing through the fixing device from the lower side as described above, if the curl correction roller is provided, the paper path that has been bent sharply is further bent. Will be. This is because when the paper P to be discharged is to be discharged almost horizontally in the horizontal direction, the paper discharge device using a pair of paper discharge rollers enters the nip of the paper discharge roller pair from the horizontal direction as it is. It is discharged horizontally. However, in the discharging device including the pair of curl correction rollers 102 and 103, as shown in FIG. 5, if the nip between the discharge roller 101 and the curl correction roller 102 is not inclined and entered lower than the horizontal, the discharge is performed. The paper P that passes through the nip between the roller 101 and the curl correction roller 103 cannot be discharged almost horizontally.

  Therefore, in the apparatus provided with the curl correction roller, the sheet that has passed through the fixing device is bent more rapidly before being discharged. For this reason, when the paper is thick paper or the like, as shown in FIG. 6, there is a case where the paper hits the discharge roller 101 without being bent and jammed. Therefore, in this type of image forming apparatus, it has been necessary to select whether to limit the transfer material that can be used, to increase the height of the apparatus, or to widen the width of the apparatus to alleviate the sharp bending of the conveyance path. .

  However, it is not acceptable to limit the types of paper that can be used as a transfer material as an image forming apparatus. However, increasing the height or expanding the width of the apparatus is not acceptable. There wasn't.

  In view of the above-described conventional circumstances, the present invention provides a paper discharge device and an image forming apparatus that can substantially eliminate restrictions on the types of paper that can be used without increasing the height even if the device can correct curl. The purpose is to do.

  In order to solve the above-mentioned problems, the present invention provides a recording medium that has been passed through the fixing unit from the bottom to the top and then changed in direction to the side, along the discharge roller and the circumferential direction of the discharge roller. In the paper discharge device for discharging paper by a plurality of opposing rollers, an angle of entering a nip formed by the paper discharge roller and a roller on the upstream side in the recording medium conveying direction is obliquely downward, and the paper discharge roller The belt is configured as a belt holding roller around which a belt for guiding the medium toward the nip is wound, and the belt is wound around a belt holding roller disposed on the upstream side of the paper discharge roller in the recording medium conveyance direction. The belt is configured as a part of an outer conveyance path in which a traveling side that travels from the belt holding roller toward the paper discharge roller guides the recording medium, and an inclination angle of the belt Suggest sheet discharging device, characterized in that substantially the same angle as the angle of entry into substantially the nip.

  In order to solve the above-described problem, the present invention provides a recording medium that is converted into a direction that substantially folds back with respect to a conveyance direction that passes through the fixing unit after passing through the fixing unit. In a paper discharge device that discharges paper by a plurality of opposing rollers arranged along the circumferential direction, the direction-changed recording medium is sandwiched by a nip formed by the paper discharge roller and an opposing roller upstream in the recording medium conveyance direction. A belt unit configured to convey and provided at an outer periphery of the conveyance path to change the direction, and to change a conveyance direction at the leading end of the recording medium and to guide the nip; The paper discharge device is characterized in that it is wound around a roller and a belt holding roller arranged upstream of the paper discharge roller in the recording medium conveyance direction.

  In the present invention, the leading end of the recording medium is in contact with a portion of the belt between the belt holding roller and the paper discharge roller, except for a portion wound around the belt wheel and the paper discharge roller. It is effective when guided to the nip.

Furthermore, the present invention is effective when the angle formed by the direction in which the recording medium enters at the point where the recording medium contacts the belt and the guide travel side is an acute angle.
Furthermore, the present invention is effective when the angle formed by the belt and the horizontal line at the point where the recording medium contacts the belt is an acute angle.

  In order to solve the above problems, the present invention proposes an image forming apparatus using the paper discharge device according to any one of claims 1 to 5.

  According to the present invention, in a paper discharge device having a paper discharge roller and a plurality of opposed rollers arranged along the circumferential direction of the paper discharge roller, even a thick paper such as thick paper can be used without increasing the size of the device. The paper can be discharged stably, and the restriction on the types of paper that can be used can be almost eliminated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a vertical sectional view showing an example of an image forming apparatus. The image forming apparatus shown here has an image carrier 2 made of a drum-shaped photoconductor disposed in a main body 1 thereof. During the printing operation, the image carrier 2 is driven to rotate counterclockwise in FIG. 1, and at this time, the image carrier 2 is charged to a predetermined polarity by the charging roller 3. The charged image carrier 2 is irradiated with light-modulated laser light L emitted from the optical writing device 4, whereby an electrostatic latent image is formed on the image carrier 2. The electrostatic latent image is visualized as a toner image by the developing device 5.

  On the other hand, a paper feed cassette 6 containing paper P and a paper feed device 8 having a paper feed roller 7 are disposed in the lower part of the image forming apparatus main body 1. Is sent in the direction of arrow A. The fed sheet is fed between the image carrier 2 and the transfer roller 10 by the registration roller pair 9 at a predetermined timing. At this time, a predetermined transfer voltage is applied to the transfer roller 10, whereby the toner image on the image carrier 2 is transferred to the paper. The sheet on which the toner image has been transferred is further conveyed upward and passes between the fixing roller 12 and the pressure roller 13 of the fixing device 11, and at this time, the toner image on the sheet is fixed by the action of heat and pressure. On the other hand, the transfer residual toner adhering to the image carrier after the toner image transfer is removed by the cleaning device 14.

  The sheet passing through the fixing device 11 is guided to the sheet discharge path 15 as indicated by an arrow B, and is discharged to the sheet discharge tray 16 through the sheet discharge apparatus 20 shown in FIG. The discharged sheet can be taken out from an opening provided in the front of the apparatus between the document reading unit 17 and the discharge tray 16.

  The paper discharge device 20 is provided with a discharge roller 21 that forms a main part thereof, and a pair of curl correction rollers 22 and 23 that are disposed along the circumferential direction so as to face the discharge roller 21. The curl correction rollers 22 and 23 are configured to be able to contact and separate from the discharge roller 21 independently. FIG. 3 is a view showing one of the contact / separation mechanisms. The curl correction rollers 22 and 23 are respectively mounted on rotatable holders 25 and 26 using a support shaft 24 supported by a support bracket 24A as a common fulcrum. It is supported. As shown in FIG. 4, the support bracket 24A is fastened and fixed to a support member 40 supported in the image forming apparatus. Although the discharge roller 21 will be described in detail later, the discharge roller 21 is also configured as a driving belt holding roller of the belt conveyance unit 30. The belt conveyance unit 30 is a pulley 32 as a belt holding roller provided on the upstream side in the paper conveyance direction from the discharge roller. A belt 31 is wound around the belt.

  Of the holders 25 and 26, in the holder 25 that pivotally supports the curl correction roller 21 located on the upstream side in the moving direction (the direction indicated by the arrow in FIG. 3) corresponding to the transport direction of the paper P, the support shaft 24 is The curl correction roller 22 is supported at one swing end as a boundary, and one end of an elastic body 27 such as a tension spring shown in FIG. 4 is hooked on the other swing end. As a result, a counterclockwise rotational bias is applied to press the curl correction roller 22 against the discharge roller 21. In the holder 26 that pivotally supports the curl correction roller 23 located on the downstream side in the moving direction of the paper P, the curl correction roller 23 is supported on one swing end with the support shaft 24 as a boundary, and the other swing end has One end of an elastic body 28 such as a compression spring shown in FIG. 4 is disposed, and the curl correction roller 23 is brought into pressure contact with the discharge roller 21 by applying a clockwise rotation bias in FIG.

  The holders 25 and 26 are biased in a direction in which the distance between the axes of the curl correction rollers 22 and 23 is narrowed by the biasing of the elastic bodies 27 and 28. The nip portions 23 are in pressure contact with each other, and constitute a nip portion that can hold and convey the paper P at a position where it is in pressure contact with the discharge roller 21.

  A guide member for guiding the movement of the paper P is provided between the holders 25 and 26. In the configuration shown in FIG. 3, a curl correction roller 23 positioned on the downstream side in the movement direction of the paper P is pivotally supported. The guide 26A is located near the peripheral surface of the discharge roller 21 in the holder 26 and extends toward the holder 25 on the upstream side in the movement direction.

  Since the present embodiment is configured as described above, when the paper P enters as shown by an arrow in FIG. 3, the paper moves along the peripheral surface of the discharge roller 21 by the curl correction rollers 22 and 23. The curl is corrected by folding back in the direction opposite to the direction in which the curl is generated. When the leading edge of the paper P enters the nip portion formed by the curl correction roller 22 and the discharge roller 21 positioned on the upstream side in the movement direction of the paper P, the curl correction roller 22 is discharged according to the thickness of the paper P. It is displaced in the direction that changes the contact state.

  When the paper P is thick, the amount of the curl correction roller 22 moving away from the discharge roller 21 increases. However, the curl correction roller 23 located on the downstream side in the movement direction of the paper P is independent of the upstream curl correction roller 22. Thus, it is in pressure contact with the discharge roller 21. For this reason, even when the upstream curl correction roller 22 is separated from the discharge roller 21, the pressure contact state with the discharge roller 21 is maintained. Thereby, even when the pressing force against the discharge roller 21 in the curl correction roller 22 on the upstream side in the movement direction is reduced, the paper P has a holding and conveying force secured by the curl correction roller 23 located on the downstream side in the movement direction. Therefore, it can move along the direction in which the curl is corrected, that is, along the peripheral surface of the discharge roller 21, and the curl is folded back in the direction opposite to the direction in which the curl is generated.

  Thus, it is possible to correct the curl and prevent a problem such as a jam caused by the curl. However, as described above, the paper P discharged through the paper discharge device 20 is directed at a considerably steep angle. It must be converted.

  Therefore, as described above, the paper discharge device 20 of the present embodiment is provided with the belt conveying means 30 as a belt holding roller for driving the discharge roller 21, and the belt 31 wound around the discharge roller 21 and the pulley 32 is used. The paper P is smoothly guided to the nip between the discharge roller 21 and the curl correction roller 22.

  As shown in FIGS. 3 and 4, the belt conveying means 30 is configured such that the leading end of the paper P conveyed through the fixing device 11 is between the belt pulley 32 and the paper discharge roller 21 in the belt traveling direction. It is important to arrange them so as to abut (contact) the guide travel surface 31a excluding the portion wound around 21 and the pulley 32. That is, if the point at which the leading edge of the paper P abuts on the conveyance belt 31 is Q, the Q point is a portion of the guide travel surface 31a that should be called the “effective conveyance surface” of the conveyance belt 31, and the leading edge of the paper P is the Q point. Thus, a stable and moderate elastic displacement / deformation state of the conveying belt 31 is obtained, and the leading end of the sheet P is reliably contacted with the guide travel surface 31a of the conveying belt 31 without causing repulsion of the leading end of the sheet P. Abut.

  In the paper discharge device 20, if the angle formed between the horizontal line at the point Q of the conveyor belt 31 and the guide travel surface 31a of the conveyor belt 31 is θ1, θ1 is an acute angle. Furthermore, if the angle formed between the guide travel surface 31a of the conveyor belt 31 at the point Q and the paper entry direction is θ2, θ2 is also set to be an acute angle.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, Various modifications can be made.
For example, in the above embodiment, as shown in FIG. 4, the pair of curl correction rollers 22 and 23 is provided at two locations, but the pair of curl correction rollers 22 and 23 may be one, and in this case Of course, the belt conveying means 30 is also provided at one place corresponding to the pair of curl correction rollers 22 and 23.

1 is an overall schematic diagram illustrating an embodiment of an image forming apparatus according to the present invention. 3 is an enlarged explanatory view showing a paper discharge unit from a fixing unit of the image forming apparatus. FIG. It is a figure which shows the structure which shows the paper discharge apparatus which concerns on this invention. FIG. 3 is an exploded perspective view illustrating a configuration of a paper discharge device according to the present invention. It is explanatory drawing which shows the conventional paper discharge apparatus. It is explanatory drawing which shows the problem which shows the conventional paper discharge apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Fixing device 20 Paper discharge device 21 Paper discharge roller 22, 23 Curl correction roller 30 Belt conveyance means 30
31 Conveying belt 31a Guide running surface 32 Pulley

Claims (6)

After passing through the fixing means from below to above, the recording medium whose direction has been changed to the side is discharged by a discharge roller and a plurality of opposing rollers arranged along the circumferential direction of the discharge roller. In paper equipment,
The angle of entering the nip formed by the discharge roller and the upstream roller in the recording medium conveyance direction is obliquely downward,
The paper discharge roller is configured as a belt holding roller around which a belt for guiding the recording medium toward the nip is wound, and the belt is disposed upstream of the paper discharge roller in the recording medium conveyance direction. It is wrapped around the belt holding roller,
The belt is configured as a part of an outer conveyance path in which a running side that runs from the belt holding roller toward the paper discharge roller guides a recording medium,
A paper discharge device characterized in that an inclination angle of the belt is substantially the same as an angle of entering the nip. After passing through the fixing means, the recording medium converted into a direction that is almost folded back with respect to the conveying direction passing through the fixing means is a discharge roller and a plurality of opposing rollers arranged along the circumferential direction of the discharge roller. In the paper discharge device for discharging paper
The direction-converted recording medium is sandwiched and conveyed by a nip formed by the discharge roller and a counter roller on the upstream side in the recording medium conveyance direction,
A belt means provided on the outer periphery of the conveyance path for changing the direction, for changing the conveyance direction of the leading edge of the recording medium and guiding the nip;
The paper discharge device, wherein the belt means is wound around the paper discharge roller and a belt holding roller disposed upstream of the paper discharge roller in the recording medium conveyance direction.   3. The paper discharge device according to claim 1, wherein a leading end of the recording medium is wound around the belt wheel and the paper discharge roller between the belt holding roller and the paper discharge roller of the belt. A paper discharge device which is guided to the nip in contact with a portion other than the portion.   4. The paper discharge device according to claim 3, wherein an angle formed by the direction in which the recording medium enters and the guide travel side at a point where the recording medium contacts the belt is an acute angle.   5. The paper discharge device according to claim 3, wherein an angle formed by the belt and a horizontal line at a point where the recording medium contacts the belt is an acute angle.   An image forming apparatus using the paper discharge device according to claim 1.

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