JP2009067491A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct recording paper bent along the circumference of a fixation roller and smoothly and securely discharge the recording paper to a paper discharge part by a simple and inexpensive constitution in a laser-beam printer. <P>SOLUTION: The image forming device is provided with a discharge roller 30 for discharging recording paper P passed through the fixation roller and first and second pinch rollers 31, 32 for pressing the recording paper P against the discharge roller 30, etc. The discharge roller 30 is arranged at the back face side of the bent recording paper P and the first and second pinch rollers 31, 32 are arranged at the front face side of the bent recording paper P. The first pinch roller 31 is disposed at the upstream side of the carrying path of the recording paper P and the second pinch roller 32 at the downstream side. The abutment face of the second pinch roller 32 made to abut on the discharge roller 30 is formed to have larger surface roughness compared to the abutment face of the first pinch roller 31 so as to swiftly kick out the rear end of the recording paper P to the discharge direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on recording paper, and more particularly to a laser beam printer that forms an image by scanning a photosensitive drum with a laser beam.

  2. Description of the Related Art Conventionally, various studies have been made on recording paper transport mechanisms of image forming apparatuses in order to stably transport recording paper. For example, Patent Document 1 discloses a transport mechanism in which a predetermined frictional surface is formed on the surface of a paper feed roller so that a stable frictional force can be obtained between recording papers. Patent Document 2 discloses an image forming apparatus in which a high friction area is formed on the surface of a paper feed roller. Patent Document 3 discloses an image forming apparatus in which a surface of a paper feed roller is subjected to a texture with a predetermined roughness. Patent Documents 4 and 5 disclose techniques relating to a paper feed roller in an inkjet image forming apparatus.

  In general, in a laser beam type image forming apparatus, a recording sheet on which a toner image is fixed by a fixing roller is driven, and a sheet discharge roller for discharging the recording sheet to a sheet discharge unit is disposed opposite to the sheet discharge roller. A pinch roller that presses the recording paper against the paper discharge roller is provided. When the recording paper passes through the fixing roller, it tends to be curved (curled) along the circumference of the fixing roller.

However, it is difficult to correct the recording paper that is curved along the circumference of the fixing roller by using any of the techniques disclosed in any of the above patent documents. There was a problem that was deposited.
Japanese Utility Model Publication No. 5-058301 Japanese Patent Laid-Open No. 2000-0666545 Japanese Patent Laid-Open No. 5-221059 JP 2000-038233 A Japanese Patent Laid-Open No. 11-116090

  The present invention has been made to solve the above-described problems, and corrects the recording paper curved along the circumference of the fixing roller with a simple and inexpensive configuration, and smoothly and reliably in the paper discharge unit. An object of the present invention is to provide an image forming apparatus capable of discharging.

In order to achieve the above object, the invention of claim 1
A toner image forming means for forming a toner image on the surface of the recording paper, and a fixing roller for fixing the toner image on the recording paper by applying predetermined heat and pressure to the recording paper on which the toner image is formed by the toner image forming means. An image forming apparatus including a discharge roller disposed on the back side of the recording paper curved by the fixing roller and driving and discharging the recording paper.
A first pinch roller disposed on the surface side of the recording paper curved by the fixing roller and pressing the recording paper against the discharge roller; and a surface side of the recording paper curved by the fixing roller, A second pinch roller disposed on the downstream side of the conveyance path of the recording paper relative to the one pinch roller and pressing the recording paper against the discharge roller;
The contact surface of the second pinch roller with the discharge roller is formed to have a rougher surface than the contact surface of the first pinch roller with the discharge roller.

The invention of claim 2 is the image forming apparatus according to claim 1,
A pinch roller support member that rotatably supports the first pinch roller and the second pinch roller, a guide mechanism that guides the pinch roller support member in a radial direction of the discharge roller, and the pinch roller support member And an urging member for urging in the direction of the discharge roller.

The invention of claim 3 is the image forming apparatus according to claim 2,
The guide mechanism has a pair of bar-shaped protrusions extending in the radial direction of the paper discharge roller in the vicinity of both ends of the pinch roller support member, and a pair of guide holes into which the bar-shaped protrusions are inserted. It is.

  According to the first aspect of the present invention, since the recording paper is pressed against the discharge roller by the first pinch roller and the second pinch roller arranged on the surface side of the recording paper, the recording paper is discharged when passing through the discharge roller. It is curved along the circumference of the roller with the back side as the inside. Since the recording paper immediately before entering the discharge roller is curved with the fixing roller as the inner surface, the recording paper is discharged by the discharge roller, the first pinch roller, and the second pinch roller. Will be canceled. Thereby, the curvature of the recording paper is corrected and smooth discharge becomes possible. At this time, since the contact surface of the second pinch roller is formed to be rougher than the contact surface of the first pinch roller, the friction between the recording paper and the second pinch roller is increased, and the recording paper The rear end is kicked out vigorously in the discharge direction by the second pinch roller. As a result, the recording paper can be reliably discharged, and conveyance failure such as paper jam in the vicinity of the second pinch roller can be prevented. Further, since the frictional force between the recording paper and the second pinch roller can be ensured without putting a rubber band or the like on the second pinch roller, the configuration is simplified and the cost of the apparatus can be reduced. Moreover, since it is not necessary to form the contact surface with a discharge roller roughly about the 1st pinch roller, it becomes possible to hold down the component unit price at low cost, and this contributes to the further cost reduction of an apparatus.

  According to the second aspect of the present invention, since the pinch roller support member is configured to be movable in the radial direction of the discharge roller by the guide mechanism, the pinch roller support member moves according to the thickness of the recording paper. Thereby, the pressing force of the first pinch roller and the second pinch roller can be optimized according to the recording sheets having different thicknesses, and smooth discharge becomes possible.

  According to the invention of claim 3, since the pinch roller support member moves while maintaining a posture parallel to the axis of the paper discharge roller, the shaft of the paper discharge roller and the shafts of the first pinch roller and the second pinch roller The first pinch roller and the second pinch roller follow the recording paper while maintaining the parallelism. As a result, the distribution of the pressing force by the first pinch roller and the second pinch roller becomes uniform in the axial direction of the paper discharge roller, and it is possible to prevent a conveyance failure such as skew (skew) and smooth discharge.

  An image forming apparatus according to an embodiment of the invention will be described with reference to the drawings. FIG. 1 shows a laser beam printer 1 which is a configuration example of an image forming apparatus. The laser beam printer 1 includes a photosensitive drum (toner image forming means) 2, a cleaner 3, a charger 4, a laser scanning unit 5, a developing brush 6, a transfer roller 7, and a transfer roller 7 on which a photosensitive member is applied. On the other hand, a fixing roller (fixing means) 8 disposed on the downstream side in the conveyance direction of the recording paper P, a paper feed tray (recording paper holding means) 9 loaded with the recording paper P, and a printed recording paper P are accumulated. The paper discharge unit 10, the recording paper P loaded in the paper feed tray 9, the recording paper transport mechanism (transport means) 11 that transports the recording paper P to the position of the photosensitive drum 2, and the recording paper P that has passed through the fixing roller 8 are discharged. A recording paper discharge mechanism 12 that discharges to the unit 10 and a power circuit board that supplies power to each unit of the apparatus are configured. Each of the above components is mounted and supported on a metal frame 13 or the like disposed on the bottom of the laser beam printer 1 or the like. Further, a cover member 14 is mounted on the frame 13 so as to cover the above-described components and form the exterior of the laser beam printer 1, and on the rear side thereof, the recording paper P jammed in the recording paper transport mechanism 11 is removed. Alternatively, a door member 15 for replacing a later-described toner cartridge 17 is provided so as to be freely opened and closed.

  The cleaner 3 removes toner and paper dust before one stroke (one rotation) adhering to the surface of the photosensitive drum 2 and cleans the drum surface. The charger 4 uniformly charges the surface of the photosensitive drum 2 cleaned by the cleaner 3. The laser scan unit 5 forms a latent image by irradiating the surface of the photosensitive drum 2 charged by the charger 4 while scanning the laser beam L. The developing brush 6 is attached to a toner cartridge 17 filled with toner, and forms a toner image by attaching toner to a portion of the surface of the photosensitive drum 2 where a latent image is formed. The transfer roller 7 is provided so as to oppose the surface of the photosensitive drum 2, and charges the surface of the recording paper P while pressing the recording paper P against the surface of the photosensitive drum 2. The formed toner image is transferred onto the recording paper P. Electric power necessary for the transfer is supplied from the power circuit board. The recording paper P on which the image is formed on the surface by the transfer roller 7 is conveyed to the fixing roller 8. The fixing roller 8 fixes the toner by applying heat and pressure while sandwiching the recording paper P together with the pressing roller 16 disposed opposite to the fixing roller 8. Heat for fixing the toner is supplied from a heater (for example, a halogen lamp) built in the fixing roller 8. A fixing voltage generated by the power supply circuit board is applied to the heater. The recording paper transport mechanism 11 has a pick roller 21 that sends out the recording paper P loaded in the paper feed tray 9. The pick roller 21 is rotatably supported by a subframe 23 in an upright posture via a rotation shaft 22.

  2 and 3 show the configuration of the recording paper discharge mechanism 12. The recording paper discharge mechanism 12 drives the recording paper P that has passed through the fixing roller 8 to discharge the recording paper P to the paper discharge unit 10, and the first pinch roller 31 and the second pinch roller 31 that press the recording paper P against the discharge roller 30. The pinch roller 32, the pinch roller support member 33 that rotatably supports the first pinch roller 31 and the second pinch roller 32, the guide mechanism 34 that guides the pinch roller support member 33, and the pinch roller support member 33 are energized. The urging member 35 and the like are configured. A plurality of first pinch rollers 31, second pinch rollers 32, pinch roller support members 33, guide mechanisms 34, and urging members 35 are arranged side by side in the axial direction of the discharge roller 30.

  The recording paper P that has passed through the fixing roller 8 tends to be bent along the circumference of the fixing roller 8 with the surface (front surface: print surface) being the inner side. The discharge roller 30 is disposed on the back side of the curved recording paper P. The first pinch roller 31 and the second pinch roller 32 are arranged on the surface side of the curved recording paper P. The first pinch roller 31 is disposed on the upstream side (the fixing roller 8 side) of the recording paper P conveyance path, and the second pinch roller 32 is disposed on the downstream side (the paper discharge unit 10 side). When the first pinch roller 31 and the second pinch roller 32 press the recording paper P to the circumference of the discharge roller 30, the recording paper P is curved along the circumference of the discharge roller 30 with the back surface inside. Become. The second pinch roller 32 is made of synthetic resin and has a contact surface 32 a that contacts the discharge roller 30. The contact surface 32a is formed to have a rougher surface than the contact surface 31a of the first pinch roller 31 with the discharge roller 30 by performing a texture process or a blast process. As shown in FIG. 2, the second pinch roller 32 is arranged so that the rotation shaft thereof is positioned downstream of the conveyance path in the horizontal direction with respect to the rotation shaft of the discharge roller 30. Therefore, when the trailing edge of the recording paper P passes directly above the second pinch roller 32, the trailing edge of the recording paper P is separated from the discharge roller 30 and driven only by the second pinch roller 32. . At this time, since the contact surface 32a of the second pinch roller 32 is formed to be rough, the rear end of the recording paper P is kicked out vigorously in the discharge direction by the second pinch roller 32.

  The guide mechanism 34 includes a pair of rod-shaped protrusions 34a extending in the radial direction of the discharge roller 30 in the vicinity of both ends of the pinch roller support member 33, and a pair of guide holes 40a into which the rod-shaped protrusions 34a are inserted. The pinch roller support member 33 is movably guided in the radial direction of the discharge roller 30. The guide hole 40 a is formed in the housing 40 of the laser beam printer 1. The biasing member 35 biases the pinch roller support member 33 guided by the guide mechanism 34 in the direction of the discharge roller 30.

  As described above, according to the laser beam printer 1 of the present embodiment, the recording paper P is pressed against the discharge roller 30 by the first pinch roller 31 and the second pinch roller 32 arranged on the front side of the recording paper P. Therefore, when the recording paper P passes through the discharge roller 30, the recording paper P is curved along the circumference of the discharge roller 30 with the back surface as the inner side. Since the recording paper P immediately before entering the discharge roller 30 is curved with the fixing roller 8 facing the inside, the curvature by the fixing roller 8 is curved by the discharge roller 30, the first pinch roller 31 and the second pinch roller 32. This cancels out when the recording paper P is discharged. Thereby, the curvature of the recording paper P is corrected and smooth discharge becomes possible. At this time, since the contact surface 32a of the second pinch roller 32 is formed to be rougher than the contact surface 31a of the first pinch roller 31, the friction between the recording paper P and the second pinch roller 32 is reduced. The rear end of the recording paper P is kicked out vigorously in the discharge direction by the second pinch roller 32. As a result, the recording paper P is reliably discharged to the paper discharge unit 10, and conveyance failure such as paper jam in the vicinity of the second pinch roller 32 can be prevented. Further, since the frictional force between the recording paper P and the second pinch roller 32 can be secured without putting a rubber band or the like on the second pinch roller 32, the configuration becomes simple and the cost of the apparatus can be reduced. . Moreover, since it is not necessary to form the contact surface 30a with the discharge roller 30 roughly with respect to the first pinch roller 31, it is possible to keep the cost of parts low, which further reduces the cost of the apparatus. To contribute.

  Further, since the pinch roller support member 33 is configured to be movable in the radial direction of the discharge roller 30 by the guide mechanism 34, the pinch roller support member 33 moves according to the thickness of the recording paper P. Thereby, the pressing force of the first pinch roller 31 and the second pinch roller 32 can be optimized according to the recording paper P having different thicknesses, and smooth discharge becomes possible. Further, since the pinch roller support member 33 is guided by the pair of rod-shaped convex portions 34a formed in the vicinity of both ends of the pinch roller support member 33 and the pair of guide holes 40a, the pinch roller support member 33 becomes the discharge roller. Move while maintaining a posture parallel to the 30 axis. For this reason, the first pinch roller 31 and the second pinch roller 32 follow the recording paper while maintaining the parallelism between the shaft of the discharge roller 30 and the shafts of the first pinch roller 31 and the second pinch roller 32. To do. As a result, the distribution of the pressing force by the first pinch roller 31 and the second pinch roller 32 becomes uniform in the axial direction of the discharge roller 30, and conveyance failure such as skew (skew) can be prevented and smooth discharge becomes possible.

  The present invention is not limited to the configuration of the above-described embodiment, and the discharge roller 30 is at least on the back side of the recording paper P curved by the fixing roller 8, and the first pinch roller 31 and the second pinch roller 32 are on the front side. Are arranged, and the contact surface 32a of the second pinch roller 32 on the downstream side may be rougher than the contact surface 31a of the first pinch roller 31 on the upstream side. The present invention can be modified in various ways. For example, the pinch roller support member 33 and the guide mechanism 34 are not limited to the shapes shown in FIG.

The figure which shows the structure of the laser beam printer by one Embodiment of this invention. FIG. 3 is a side view showing a configuration of a recording paper discharge mechanism in the laser beam printer. The perspective view which shows the structure of the recording paper discharge mechanism.

Explanation of symbols

1 Laser beam printer 2 Photosensitive drum (toner image forming means)
8 Fixing roller (fixing means)
11 Recording paper transport mechanism (transport means)
30 discharge roller 31 first pinch roller 32 second pinch roller 32a contact surface 33 pinch roller support member 34 guide mechanism 34a rod-like convex portion 40a guide hole

Claims (3)

A toner image forming means for forming a toner image on the surface of the recording paper, and a fixing roller for fixing the toner image on the recording paper by applying predetermined heat and pressure to the recording paper on which the toner image is formed by the toner image forming means. An image forming apparatus including a discharge roller disposed on the back side of the recording paper curved by the fixing roller and driving and discharging the recording paper.
A first pinch roller disposed on the surface side of the recording paper curved by the fixing roller and pressing the recording paper against the discharge roller; and a surface side of the recording paper curved by the fixing roller, A second pinch roller disposed on the downstream side of the conveyance path of the recording paper relative to the one pinch roller and pressing the recording paper against the discharge roller;
The image forming apparatus according to claim 1, wherein a contact surface of the second pinch roller with the discharge roller is formed to be rougher than a contact surface of the first pinch roller with the discharge roller.   A pinch roller support member that rotatably supports the first pinch roller and the second pinch roller, a guide mechanism that guides the pinch roller support member in a radial direction of the discharge roller, and the pinch roller support member The image forming apparatus according to claim 1, further comprising a biasing member that biases in the direction of the discharge roller.   The guide mechanism has a pair of rod-shaped protrusions extending in the radial direction of the paper discharge roller in the vicinity of both ends of the pinch roller support member, and a pair of guide holes into which the rod-shaped protrusions are inserted. The image forming apparatus according to claim 2.

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