JP2010241569A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the involvement of a foreign matter or the like in a paper discharge part by a simple construction. <P>SOLUTION: The image forming device includes pairs of paper discharge rollers 25, 26 discharging record materials formed with an image to the outside of a device body in which axial opposite ends of a roller shaft 28 attached with the one pair of paper discharge rollers 26 are rotatably supported by bearings 29, a paper discharge gear G1 attached to one of axial ends of the roller shaft 28 is meshed with a drive gear G2, and the roller shaft 28 and the paper discharge rollers 26 attached to the shaft are rotatively driven by a drive force transmitted to the roller shaft 28 from the drive gear G2 via the paper discharge gear G1. Springs (biasing means) 31 for movably supporting the bearings 29 and biasing the bearings 29 in a direction in which the paper discharge gear G1 meshes with the drive gear G2 are provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a pair of paper discharge rollers for discharging a recording material on which an image is formed to the outside of the apparatus main body.

  In an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, a sheet as a recording material is fed to an image forming unit, and a toner image formed on an image carrier in the image forming unit is placed on the sheet. After the transfer, a series of processes are executed in which the toner image is fixed on a sheet, and the sheet on which the toner image is fixed is discharged out of the apparatus main body by a pair of discharge rollers.

  By the way, the sheet on which the toner image is fixed is discharged to the outside of the apparatus main body by a pair of discharge rollers, but one of the pair of discharge rollers is connected to a roller shaft, and the other discharge roller is connected to this one discharge roller. The roller is pressed by a spring. Both ends of the roller shaft in the axial direction are rotatably supported by bearings, and a paper discharge gear is attached to one end of the roller shaft in the axial direction, and the paper discharge gear meshes with the drive gear.

  Thus, when the driving force is transmitted from the drive gear to the roller shaft through the paper discharge gear, the roller shaft and one paper discharge roller bonded to the roller shaft are rotationally driven to fix the toner image. Are nipped and conveyed by a pair of paper discharge rollers rotating in contact with each other and discharged to a paper discharge tray outside the apparatus main body.

  By the way, if a foreign object or the like enters the gap between the paper discharge roller attached to the roller shaft and the image forming apparatus main body, the foreign object is caught and the rotation of the paper discharge roller is obstructed, and the paper discharge is normal. The problem that it will not be performed occurs.

  As means for solving the above problem, for example, Patent Document 1 proposes a roll safety device in which a plurality of roll reverse rotation driving switches are provided and the roll is driven after the safety confirmation operation. There has been proposed an image forming apparatus provided with a detection sensor using a light beam in order to detect entry of a foreign object such as a hand into a paper discharge unit. Also, in Patent Document 3, a door that can be opened and closed is provided on the front surface of the paper discharge unit, and the door is locked with a key so as to prevent the contents of the paper discharged on the paper discharge tray from being exposed and taking out the paper. An image forming apparatus has been proposed.

JP 2008-247490 A JP 2005-179040 A JP-A-8-339102

  However, the configurations proposed in Patent Documents 1 and 2 have a problem that cost increases cannot be avoided because many sensors and switches are used. In particular, a sensor using a light beam may be erroneously detected depending on the environment, and is not sufficient for safety measures.

  The configuration proposed in Patent Document 3 is mainly for preventing the contents of the paper from being exposed and taking out the paper, and is insufficient as a safety measure against the entry of foreign matter into the paper discharge section. This is because if the door is opened due to forgetting to close the key, foreign matter or the like may be caught in the paper discharge unit.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of preventing foreign matter and the like from being caught in a paper discharge unit with a simple configuration.

  In order to achieve the above object, the invention described in claim 1 is provided with a pair of paper discharge rollers for discharging a recording material on which an image is formed to the outside of the apparatus main body, and a roller formed by binding one of the paper discharge roller pairs. Both ends of the shaft in the axial direction are rotatably supported by bearings, and a paper discharge gear connected to one end of the roller shaft in the axial direction is engaged with the drive gear, and transmitted from the drive gear to the roller shaft through the paper discharge gear. In the image forming apparatus that rotationally drives the roller shaft and the paper discharge roller bonded thereto by a driving force applied, the bearing is movably supported, and the paper discharge gear meshes with the drive gear. An urging means for urging in the direction is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, a guide member that slidably supports the bearing is provided, and the guide member is engaged with the bearing to hold the bearing in a normal position. A protrusion is formed.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, there is provided detection means for detecting movement of the bearing, and when the detection means detects movement of the bearing, driving of the drive gear is stopped. It is characterized by.

  According to the first aspect of the present invention, when a foreign object or the like enters from a gap between the paper discharge roller that rotates together with the roller shaft and the image forming apparatus main body, the bearing that supports the roller shaft serves as the urging force of the urging means. Since the paper discharge gear attached to the roller shaft moves away from the drive gear and the meshing of both gears is released, the transmission of the driving force to the roller shaft is interrupted, and the roller shaft The rotation of the paper discharge roller bound thereto is stopped, and foreign matter is prevented from being caught. When the foreign matter or the like is removed, the bearing and the roller shaft are returned to the original normal position by the urging force of the urging means, and the paper discharge gear attached to the roller shaft is reengaged with the drive gear. The pair rotates and the paper discharge is resumed. As described above, according to the present invention, it is possible to prevent entrainment of foreign matters or the like with a simple and inexpensive mechanical configuration without using expensive electronic components.

  According to the second aspect of the invention, since the bearing engages with the protrusion formed on the guide member and is held in the normal position (position where the paper discharge gear meshes with the drive gear) during normal operation, it is discharged from the drive gear. The driving force is normally transmitted to the roller shaft through the paper gear, and the pair of paper discharge rollers is rotationally driven by the roller shaft, so that the paper is stably discharged. When foreign matter or the like enters the gap between the paper discharge roller and the image forming apparatus main body, the bearing moves over the protrusion of the guide member, so that the meshing between the paper discharge gear and the drive gear is released and the roller Since the transmission of the driving force to the shaft is interrupted, the rotation of the pair of paper discharge rollers is stopped, and foreign matters are reliably prevented from being caught.

  According to the third aspect of the present invention, when the bearing moves because foreign matter or the like has entered the gap between the paper discharge roller and the image forming apparatus main body, the movement of the bearing is detected by the detecting means, and the driving of the drive gear is stopped. Therefore, the rotation of the paper discharge roller pair can be stopped more reliably, and foreign matter or the like can be reliably prevented. If not only the drive gear is driven but also the operation of the entire apparatus is stopped, it is possible to prevent wasteful conveyance of the paper and suppress consumption of the paper.

1 is a side sectional view of a laser printer according to the present invention. It is a fragmentary perspective view which shows the state of the paper discharge part at the time of normal operation | movement of the racer printer which concerns on this invention. It is a side view which shows the state of the bearing at the time of normal operation | movement of the racer printer which concerns on this invention. It is a fragmentary perspective view which shows the state of the paper discharge part at the time of abnormality of the racer printer which concerns on this invention. It is a side view which shows the state of the bearing at the time of abnormality of the racer printer which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side sectional view of a laser printer as an embodiment of an image forming apparatus according to the present invention. In the illustrated laser printer 1, a rectangular box-shaped printer body (housing) 2 has a central portion on the upper surface thereof. An inclined concave paper discharge tray 3 is provided. An openable and closable manual feed tray 4 is provided at the upper part of the front surface of the printer main body 2 (the right side in FIG. 1 is the front). The manual feed tray 4 and a manual feed tray that is rotatably provided in the printer main body 2 at the back thereof. The sheet feeding roller 5 constitutes a manual sheet feeding unit 6.

  Thus, the laser printer 1 transfers the paper P based on image data transmitted from a terminal (not shown) while transporting the paper P as a recording material along the transport path L provided in the printer body 2. The transport path L is formed in a substantially L shape in a side view and extends to the paper discharge tray 3.

  The laser printer 1 includes a cassette paper feeding unit 7 provided at a lower portion of the printer main body 2, an image forming unit 8 provided at a substantially central portion in the printer main body 2 above the cassette paper feeding unit 7, A fixing device 9 disposed behind the image forming unit 8 and a concave paper discharge unit 10 provided on the upper surface of the printer main body 2 above the fixing device 9 are provided.

  The cassette sheet feeding unit 7 stacks and stores a plurality of sheets of paper P in a rectangular tray-shaped sheet feeding cassette 11 having an open upper surface, and picks a roller 12 that picks up the sheets P in the sheet feeding cassette 11 one by one. And a feed roller 13 and a retard roller 14 for separating the taken paper P one by one and feeding them to the transport path L. The transport path L has a predetermined length after the fed paper P is temporarily held. A registration roller pair 15 is provided to be supplied to the image forming unit 8 at this timing.

  The image forming unit 8 forms an image corresponding to the image data on the paper P supplied one by one from the manual paper feeding unit 6 or the cassette paper feeding unit 7. A photosensitive drum 16 as an image carrier that is rotatably arranged on the printer, a charger 17 disposed around the photosensitive drum 16, a developing device 18 that is a developing unit, a transfer roller 19 that is a transfer unit, and a cleaning device 20, and the like. A laser scanner unit (LSU) 21 disposed above, a toner hopper 22 containing replenishing toner, and the like are provided.

  The fixing device 9 is for fixing the toner image transferred onto the paper P in the image forming unit 8 to the paper P, and includes a fixing roller 23 and a pressure roller 24 that rotate while being pressed against each other. I have. The fixing roller 23 incorporates a heating means such as a heater, and the pressure roller 24 is pressed against the fixing roller 23 with a predetermined pressure by a biasing means such as a spring, and a fixing nip is formed between them. Has been.

  Further, the paper discharge unit 10 is for discharging the paper P on which the toner image has been fixed in the fixing device 9 to the outside of the printer main body 2, and is a pair of upper and lower discharges provided at the end of the conveyance path L. A pair of paper rollers 25 and 26, a plurality of vertical rib-shaped conveyance guide ribs 27 for guiding the paper P conveyed along the conveyance path L from the fixing device 9 to the paper discharge roller pairs 25 and 26, and the printer main body 2 The paper discharge tray 3 for loading paper P to be discharged outside is provided.

  Next, an image forming operation of the laser printer 1 having the above configuration will be described.

  For example, when a print start signal is transmitted to the laser printer 1 from a terminal such as a personal computer (personal computer), the photosensitive drum 16 is moved in the direction indicated by the arrow (clockwise) in FIG. ) At a predetermined process speed, and its surface is uniformly charged to a predetermined potential by the charger 17. When a laser beam based on the image data transmitted from the terminal is output from the laser scanner unit 21 and irradiated onto the photosensitive drum 16, an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 16. Is done. Then, the electrostatic latent image formed on the photosensitive drum 16 is developed by the developing device 18 using toner as a developer to be visualized as a toner image.

  By the way, when cassette feeding is performed, the paper P stored in the paper feeding cassette 11 of the cassette paper feeding unit 7 is picked up one by one from the uppermost one by the pick roller 12, and the feed roller 13 and the retard roller 14. Are separated one by one and conveyed to the registration roller pair 15. In the registration roller pair 15, the paper P is temporarily put into a standby state and then supplied to the image forming unit 8 at a predetermined timing synchronized with the formation of the toner image on the photosensitive drum 16.

  In the image forming unit 8, the sheet P supplied to the transfer nip between the photosensitive drum 16 and the transfer roller 19 is conveyed while being pressed against the photosensitive drum 16 by the transfer roller 19, so that the surface (transfer) The toner image on the photosensitive drum 16 is transferred onto the surface) by the action of the transfer bias applied to the transfer roller 19. The sheet P on which the toner image has been transferred is conveyed to the fixing device 9 where it is heated and pressurized in the process of being sandwiched and conveyed by the fixing nip between the fixing roller 23 and the pressure roller 24. The toner image is fixed. The toner remaining on the surface of the photosensitive drum 16 (transfer residual toner) after the transfer of the toner image onto the paper P is removed by the cleaning device 20, and the photosensitive drum 16 whose surface has been cleaned is prepared for the next image forming operation. .

  Thus, the sheet P having the toner image fixed on the surface thereof by the fixing device 9 is conveyed upward along the conveyance path L toward the sheet discharge unit 10, and along the conveyance guide rib 27, the discharge roller pair 25, 26, and is sent out of the printer main body 2 while being sandwiched between the pair of paper discharge rollers 25 and 26, and is stacked on a paper discharge tray 3 provided on the upper portion of the printer main body 2 to form a series of image formations. The operation ends.

  When the user manually feeds the paper, the paper P stacked on the manual tray 4 of the manual paper feed unit 6 is supplied to the registration roller pair 15 by the manual paper feed roller 5. Through the same process, an image is formed on the paper P, and the paper P on which the image is formed is stacked on the paper discharge tray 3 outside the printer main body 2.

  Next, the gist of the present invention will be described with reference to FIGS.

  2 is a partial perspective view showing the state of the paper discharge unit during normal operation, FIG. 3 is a side view showing the state of the bearing during normal operation, and FIG. 4 is a partial perspective view showing the state of the paper discharge unit during abnormal operation. FIG. 5 is a side view showing the state of the bearing at the time of abnormality.

  As shown in FIG. 2, two pairs of the discharge roller pairs 25 and 26 are provided at a predetermined interval in the width direction, and the lower discharge roller 26 of the discharge roller pairs 25 and 26 is a roller. The upper discharge roller 25 is bonded to the shaft 28 and is pressed against the lower discharge roller 26 by a spring (not shown). Both ends of the roller shaft 28 in the axial direction are rotatably supported by bearings 29 (only one is shown in the figure), and these bearings 29 are fitted and held by a rectangular frame-shaped guide member 30 so as to be movable up and down. ing.

  A discharge gear G1 is attached to one end of the roller shaft 28 in the axial direction (front side in FIG. 2), and this discharge gear G1 meshes with a drive gear G2 disposed below the discharge gear G1. The drive gear G2 is rotationally driven in response to transmission of drive force from a motor (not shown) that is a drive source.

  By the way, a spring 31 as an urging means is mounted between each bearing 29 and the guide member 30, and the bearing 29 and the roller shaft 28 supported by the bearing 29 are bonded to the roller shaft 28. The paper discharge gear G1 is urged in a direction to mesh with the drive gear G2.

  Thus, when a normal operation is performed without foreign matter or the like entering the gap between the lower discharge roller 26 and the printer main body 2 of the discharge roller pair 25, 26, as shown in FIG. Further, the bearing 29 is urged downward by the spring 31 and is held at the normal position (lower limit position) of the guide member 30, but as shown in FIG. A projection 32 is formed to hold the bearing 29 in a normal position. Further, as shown in FIG. 5, a switch 33, which is a detecting means for detecting the movement of the bearing 29, is provided in the fitting portion 30 b in which the bearing 29 of the guide member 30 is fitted. 2 and 3, when the switch 33 is in the normal position, the switch 33 is pressed by the bearing 29 and is in the ON state.

  Then, the bearing 29 engages with the protrusion 32 formed on the guide member 30 and is held at a normal position (position where the paper discharge gear G1 meshes with the drive gear G2), and the paper discharge gear G1 is as shown in FIG. During normal operation meshed with the drive gear G2, the driving force is normally transmitted from the drive gear G2 to the roller shaft 28 through the paper discharge gear G1, and the paper discharge roller 26 is rotationally driven by the roller shaft 28. The paper discharge roller 25 pressed by the paper discharge roller 26 is driven to rotate. Accordingly, the paper P on which the toner image is formed is conveyed to the paper discharge unit 10 (see FIG. 1) and is held between the pair of paper discharge rollers 25 and 26 that rotate while being in contact with each other, and is stable outside the printer main body 2. And is stacked on a paper discharge tray 3 (see FIG. 1) formed on the upper portion of the printer main body 2.

  By the way, when foreign matter or the like enters through a gap between the lower discharge roller 26 that rotates together with the roller shaft 28 and the printer body 2, the bearing 29 that supports the roller shaft 28 resists the biasing force of the spring 31. As shown in FIGS. 4 and 5, since the protrusion 32 is pushed over and pushed up, the paper discharge gear G1 attached to the roller shaft 28 is disengaged from the drive gear G2 and the meshing of both gears G1 and G2 is released. . For this reason, the transmission of the driving force to the roller shaft 28 is interrupted, the rotation of the roller shaft 28 and the paper discharge roller 26 attached thereto is stopped, and foreign matters are prevented from being caught. Further, when the bearing 29 is pushed up along the guide member 30, as shown in FIG. 5, the pressing of the switch 33 by the bearing 29 is released, so that the switch 33 protrudes upward and enters the OFF state, and the drive gear G2 Is stopped. For this reason, it is possible to more reliably stop the rotation of the paper discharge roller pair 25 and 26 and reliably prevent foreign matters from being caught.

  Thus, in the present embodiment, when the switch 33 is turned off because foreign matter or the like has entered from the gap between the paper discharge roller 26 and the printer main body 2, not only the drive gear G2 but also the entire laser printer 1 is driven. The operation is stopped, the conveyance of the paper P that has not reached the fixing device 9 is stopped, and the paper P that has reached the fixing device 9 is forcibly discharged. And the consumption of the paper P can be suppressed.

  Thereafter, when foreign matter or the like is removed, the bearing 29 and the roller shaft 28 are returned to the normal positions shown in FIGS. 2 and 3 by the urging force of the spring 31, and the paper discharge gear G1 attached to the roller shaft 28 is driven by the drive gear G2. Therefore, the paper discharge roller pair 25, 26 rotates and the discharge of the paper P is resumed.

  As described above, according to the present invention, it is possible to obtain an effect that foreign matters can be prevented from being caught with a simple and inexpensive mechanical configuration without using expensive electronic components.

1 Laser printer (image forming device)
2 Printer body (image forming device body)
DESCRIPTION OF SYMBOLS 3 Paper discharge tray 4 Manual feed tray 5 Manual feed roller 6 Manual paper feed unit 7 Cassette paper feed unit 8 Image forming unit 9 Fixing device 10 Paper discharge unit 11 Paper feed cassette 12 Pick roller 13 Feed roller 14 Retard roller 15 Registration roller Pair 16 Photosensitive drum 17 Charger 18 Developing device 19 Transfer roller 20 Cleaning device 21 Laser scanner unit 22 Toner hopper 23 Fixing roller 24 Pressure roller 25, 26 Paper discharge roller pair 27 Guide rib 28 Roller shaft 29 Bearing 30 Guide member 30a Guide member Guide surface 30b Guide member fitting portion 31 Spring (biasing means)
32 protrusion 33 switch (detection means)
G1 paper discharge gear G2 drive gear L conveyance path P paper (recording material)

Claims (3)

A pair of paper discharge rollers for discharging the recording material on which an image is formed in the image forming unit to the outside of the apparatus main body, and both ends in the axial direction of a roller shaft formed by binding one of the pair of paper discharge rollers can be rotated by bearings. The paper discharge gear connected to one end in the axial direction of the roller shaft is meshed with the drive gear, and the roller shaft and the roller shaft are coupled to the roller shaft by the driving force transmitted from the drive gear to the roller shaft through the paper discharge gear. In an image forming apparatus that rotationally drives a bound discharge roller,
An image forming apparatus comprising: an urging unit that movably supports the bearing and urges the bearing in a direction in which a paper discharge gear meshes with the drive gear.   The image forming apparatus according to claim 1, wherein a guide member that slidably supports the bearing is provided, and a protrusion that engages the bearing and holds the bearing in a normal position is formed on the guide member.   3. The image forming apparatus according to claim 1, further comprising a detecting unit configured to detect the movement of the bearing, and stopping the driving of the driving gear when the detecting unit detects the movement of the bearing.

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