JP2007031025A - Curl correction device and image formation device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To retain stable conveying force of a curl correction roller without influenced by difference of a transfer image and a fixing temperature. <P>SOLUTION: The curl correction device 50 has a curl correction roller 22 comprising a high hardness roller 25 composed of a rigid body and an elastic roller 26 having an elastic layer 26B pressure-contacted with the high hardness roller 25 so as to be opposed to it; and a drive source 27 for giving rotation drive force to the high hardness roller 25, is arranged in a downstream side more than a fixing part 7 of a conveying passage until the paper printed/outputted in an electrophotographic process is delivered and corrects curls of the paper. Gears 33, 34 engaged with the high hardness roller 25 and the elastic roller 26 are arranged respectively and rotation drive force of the elastic roller 26 is obtained from the high hardness roller 25. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a curl correction device that is disposed downstream of a fixing portion of a conveyance path until a sheet printed out in an electrophotographic process step is discharged, and an image forming apparatus using the same. .

  2. Description of the Related Art Conventionally, there has been proposed an image forming apparatus provided with a fixing device or a means for correcting a sheet curled (curled) by the curvature of a conveyance guide formed downstream thereof.

  For example, a curl correction unit comprising a driving roller made of a rigid body such as metal and a driven roller having a sponge elastic layer formed on the outer side of a metal shaft core in a transport unit that transports paper after fixing processing by a fixing device. A roller is provided, and the driving roller and the driven roller are pressed against each other (nip) so that the elastic layer is deformed, so that the paper passing through the nip portion of the curl correction roller has a curling direction opposite to the curling direction. Corrections are made.

  Japanese Patent Application Laid-Open No. H10-228707 proposes a unit having a plurality of curl correction units in which the elastic layer is made of rubber and the driving side and driven side rollers are switched.

In the above-described prior art, the rotational driving force of the curl correction roller is given only by the gear disposed on the driving roller, and the driven roller is nipped by the driving roller. ).
Japanese Patent Laying-Open No. 2003-12215 (see paragraph 0024, FIG. 3)

  However, in such a configuration of the curl correction roller, in the paper after the fixing process sandwiched between the nip portions of the curl correction roller, a high density image is transferred on the entire surface of the front and back surfaces of the paper, and on one side. When a small amount of characters is transferred, there is a difference in conveying force even with the same size paper. Also, in models where the fixing temperature is set in several stages depending on the paper type, such as plain paper or thick paper, the surface temperature of the paper after the fixing process varies depending on the paper type, and there is a difference in the conveyance force of the curl correction roller. It is a factor that arises.

  When a difference occurs in the conveyance force of the curl correction roller as described above, the balance of the sheet conveyance speed is easily lost between the fixing unit and the curl correction roller on the downstream side. Then, the amount of deflection of the paper becomes larger than expected during that time, causing problems such as the toner being peeled off by rubbing against the conveyance guide and the paper becoming dirty.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to maintain a stable conveying force of a curl correction roller without being affected by a difference in a transfer image and a fixing temperature.

  In order to achieve the above object, the present invention provides a curl correction roller comprising a high-hardness roller comprising a rigid body and an elastic roller having an elastic layer pressed against the high-hardness roller, and a rotational driving force applied to the high-hardness roller. A curling correction apparatus for correcting the curl of the paper disposed on the downstream side of the fixing portion of the conveyance path until the paper printed out in the electrophotographic process step is discharged. Gears meshing with each other are disposed on the roller and the elastic roller, respectively, and the rotational driving force of the elastic roller is obtained from the high hardness roller.

  The gear ratio between the gear disposed on the high hardness roller and the gear disposed on the elastic roller is a gear ratio that causes the elastic roller to rotate at a constant speed or higher with respect to the high hardness roller.

  The curl correction apparatus is mounted on an image forming apparatus using an electrophotographic process such as a printer or a facsimile.

  According to the present invention, the elastic roller is not rotated with respect to the high hardness roller, but the elastic roller is rotated by obtaining a rotational driving force from the high hardness roller. A stable curling roller conveying force can be maintained without being affected.

  In particular, when the elastic roller is rotated at a constant speed or a few percent faster than the high-hardness roller, the relationship between the peripheral speed at the set fixing portion and the peripheral speed of the curl correction roller on the downstream side is as follows. It is possible to solve problems such as fluctuations in the behavior of the deflection of the paper, which are caused by the loss of balance.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 shows an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 includes a display unit 2, an operation input unit 3, a document reading unit 4 composed of a CCD or the like, and a printing unit 9. The printing unit 9 further includes a sheet feeding unit 5 having 5A including a plurality of sheet feeding units for storing and feeding the sheet P, and image formation for forming an image on the photosensitive member 10 and transferring the image onto the sheet P. A registration unit 16 that temporarily stops and bends the sheet P fed from the sheet feeding unit 5 and feeds it to the image forming unit 6; a fixing unit 7 that fixes the image on the sheet P; A paper discharge unit 8 that discharges the fixed paper P is configured.

  Further, the image forming unit 6 exposes the photosensitive member 10 that rotates clockwise in the drawing, a charging unit 11 that charges the surface of the photosensitive member 10, and the charged photosensitive member 10 to form an electrostatic latent image. An exposure unit 12; a developing unit 13 that develops the electrostatic latent image as a visible image with toner via a developing roller 13a; a transfer unit 14 that transfers the visible image of the toner onto the paper P; And a cleaning unit 15 that removes residual toner that is not transferred to the surface of the photoreceptor 10.

  Further, the fixing unit 7 includes a heat roller 18 that is heated to a fixing temperature by the heater 17 and fixes the visible image of the toner with the heat, and a pressure roller 19 that is in pressure contact with the heat roller 18.

  Further, the paper discharge unit 8 includes a conveyance roller 20 that conveys the fixed paper P along a conveyance guide 21 that is refracted upward, a curl correction roller 22 that corrects the curl of the paper, and a paper discharge tray 24. A paper discharge roller 23 for discharging the paper upward is provided.

  FIG. 2 is a plan view of the curl forcing device of the image forming apparatus. The curl correction device 50 includes the curl correction roller 22 and a motor (drive source) 27 that applies a rotational driving force to the high hardness roller 25 of the curl correction roller 22. The curl correction roller 22 has a high-hardness roller 25 made of a rigid body such as a metal integrally formed with roller shafts 25A at both ends, and a metal shaft center 26A pressed against the high-hardness roller 25 and made of sponge on the outside. And an elastic roller 26 on which an elastic layer 26B is formed. As shown in FIG. 3, the high hardness roller 25 and the elastic roller 26 are set to face each other at a distance L such that the elastic layer 26B is deformed.

  The high hardness roller 25 and the elastic roller 26 are rotatably supported by bearings 31 and 32 provided on the frame side walls 30 facing each other by a roller shaft 25A and a shaft center 26A, respectively. One end side of the roller shaft 25A of the high hardness roller 25 penetrates the bearing 31 and protrudes to the outside of the frame side wall 30, and a driven gear 28 is attached to the end portion. The driven gear 28 meshes with a driving gear 29 attached to the tip of a motor shaft 27 </ b> A that is rotationally driven by a motor 27. Therefore, when the drive gear 29 is rotationally driven by the motor 27, the driven gear 28 is rotated and the high hardness roller 25 can be rotated.

  Furthermore, roller gears 33 and 34 that mesh with the roller shaft 25A of the high hardness roller 25 and the shaft center 26A of the elastic roller 26 are arranged inside the one side wall 30 of the roller, and the high hardness roller 25 is rotated. Instead of rotating the elastic roller 26 with respect to the high hardness roller 25, the elastic roller 26 is rotated by obtaining a rotational driving force from the high hardness roller 25.

  At this time, the gear ratio between the roller gear 33 disposed on the high hardness roller 25 and the roller gear 34 disposed on the elastic roller 26 is set so that the elastic roller 26 rotates at a constant speed or several percent faster than the high hardness roller 25. Is set so that there is no delay in the set conveyance speed.

  FIG. 3 is a cross-sectional view around the curl correction roller. As indicated by an arrow X, the sheet is conveyed from the lower side to the upper side of the drawing, P1 indicates a sheet before passing through the curl correction roller 22, and P2 indicates a sheet after passing through the curl correction roller 22. When the paper P1 with curl in the right direction enters, the paper P1 receives the curl opposite to the curl by the curl correction roller 22. As a result, the curled paper P1 is corrected as indicated by P2.

  At this time, as described above, the elastic roller 26 is rotated at a constant speed or several percent faster than the high-hardness roller 25, so that the peripheral speed at the set fixing unit 7 (see FIG. 1) and its downstream side. The relationship between the peripheral speeds of the curl correction roller 22 on the side is maintained, and problems such as fluctuations in the behavior of the deflection of the paper, which are caused by the loss of balance, can be solved.

  The present invention can be used in an image forming apparatus using an electrophotographic process such as a printer or a facsimile.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a plan view of a curl forcing device of the image forming apparatus. These are sectional drawings of the curl correction roller of the said curl correction apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Display part 3 Operation input part 4 Document reading part 5 Paper feeding part 6 Image forming part 7 Fixing part 8 Paper discharge part 9 Printing part 10 Photoconductor 11 Charging part 12 Exposure part 13 Developing part 13a Developing roller 14 Transfer Section 15 Cleaning Section 16 Registration Roller 17 Heater 18 Heat Roller 19 Pressure Roller 20 Conveyance Roller 21 Conveyance Guide 22 Curl Correction Roller 23 Discharge Roller 24 Discharge Tray 25 High Hardness Roller 25A Roller Shaft 26 Elastic Roller 26A Axis Center 26B Elastic Layer 27 Motor 27 Drive source 27A Motor shaft 28 Driven gear 29 Drive gear 30 Frame side wall 31 Bearing 33 Roller gear 33, 34 Roller gear 50 Curl correction device P Paper

Claims (3)

  An electrophotographic process, comprising: a high-curing roller composed of a rigid body; and a curl correcting roller composed of an elastic roller having an elastic layer pressed against the high-hardness roller; and a drive source for applying a rotational driving force to the high-hardness roller. In the curl correction device for correcting the curl of the paper disposed downstream of the fixing portion of the conveyance path until the paper printed out in the process is discharged, the gear that meshes with the high-hardness roller and the elastic roller respectively. A curl correcting device that is arranged and obtains the rotational driving force of the elastic roller from the high hardness roller.   2. The gear ratio between the gear disposed on the high hardness roller and the gear disposed on the elastic roller is a gear ratio that causes the elastic roller to rotate at a constant speed or higher with respect to the high hardness roller. The curl straightening device described in 1.   An image forming apparatus using the curl correction apparatus according to claim 1.

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