JP2011137920A - Optical scanner and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner which is capable of suppressing rise in ambient temperature inside the housing and preventing degradation of image quality incidental to thermal deformation or the like of a polygon mirror. <P>SOLUTION: This invention is related to an optical scanner 21 that is positioned and fixed to a metal frame 37 of an image forming apparatus, in which a polygon mirror 31 being a deflection means and a polygon motor 32 rotationally driving the polygon mirror are accommodated inside a housing 28 made of resin. In the optical scanner, a bearing 39 of the polygon motor 32 and a metallic positioning pin 38 provided upright to the metal frame 37 are inserted into and fitted with each other from opposite directions in a positioning boss 28A formed in the housing 28, with the two brought into contact with each other. Also, the bearing 39 of the polygon motor 32 and the positioning pin 38 are brought into contact with each other through a highly thermally conductive cushion material 40 interposed in-between. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical scanning device for optically scanning a surface to be scanned and an image forming apparatus such as a copying machine and a printer provided with the optical scanning device.

  In an image forming apparatus such as a copying machine or a printer, an image carrier whose surface is uniformly charged by a charger is optically scanned by an optical scanning device, and an electrostatic latent image corresponding to image information is formed on the surface. The The electrostatic latent image is developed by a developing device using toner as a developer to be visualized as a toner image. The toner image is transferred onto a sheet by a transfer device and then heated and heated by a fixing device. A series of image forming operations is completed by discharging the sheet having the toner image fixed thereon by being pressed and fixed on the sheet.

  By the way, an optical scanning device that optically scans an image carrier to form an electrostatic latent image on the surface thereof is positioned and fixed on a metal frame of the image forming device, and various resins such as lenses and mirrors are provided in a resin housing. A part, a polygon mirror as a deflecting means, and a polygon motor for rotationally driving the part are housed.

  When the number of prints increases in an image forming apparatus equipped with such an optical scanning device, the ambient temperature in the housing rises due to the heat generated by the rotation of the polygon motor, causing thermal deformation of the polygon mirror, adversely affecting the focal length, etc. Since high-precision optical scanning is not performed, problems such as image quality degradation occur.

  Therefore, for example, Patent Document 1 proposes a configuration in which a blower for generating an air flow and a duct for guiding the air flow from the blower are provided in the housing of the optical scanning device.

JP 2008-268698 A

  However, in the configuration proposed in Patent Document 1, since it is necessary to provide a blower and a duct in the housing, there is a problem that the optical scanning device is increased in size and the number of parts is increased, resulting in an increase in cost.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to reduce the increase in the ambient temperature in the housing without causing an increase in size and cost, and image quality associated with thermal deformation or the like in the polygon mirror. It is an object of the present invention to provide an optical scanning device capable of preventing the deterioration of the image and an image forming apparatus including the same.

  In order to achieve the above object, an invention according to claim 1 is an apparatus which is positioned and attached to a metal frame of an image forming apparatus, and is a polygon mirror which is a deflecting means in a resin housing and a rotational drive thereof. In the optical scanning device for storing the polygon motor, the bearing of the polygon motor and the metal positioning pin erected on the metal frame are inserted and fitted to the positioning boss formed in the housing from opposite directions. , The two are brought into contact with each other.

  The invention according to claim 2 is the invention according to claim 1, characterized in that the bearing of the polygon motor and the positioning pin are brought into contact with each other via a cushion material having high thermal conductivity.

  An image forming apparatus according to a third aspect includes the optical scanning device according to the first or second aspect.

  According to the first aspect of the invention, the heat generated in the polygon motor is conducted from the bearing of the polygon motor through the metal positioning pin and radiated to the outside of the housing. With this configuration, it is possible to suppress an increase in the ambient temperature in the housing, and without causing an increase in the size and cost of the optical scanning device, it is possible to prevent deterioration in image quality due to focal length deviation due to thermal deformation of the polygon mirror. It is.

  According to the second aspect of the present invention, the heat generated in the polygon motor is conducted to the outside of the housing through the heat conductive high cushioning material and the metal positioning pin. The rise is suppressed, and the variation in the height dimension of the positioning pin is absorbed by the elastic deformation of the cushion material.

  According to the third aspect of the present invention, since the increase in the ambient temperature in the housing of the optical scanning device is suppressed and high-precision optical scanning is performed on the image carrier, a high-quality image can be stably obtained. .

1 is a side sectional view of an image forming apparatus (laser printer) according to the present invention. It is a top view which removes and shows the cover of the optical scanning device concerning the present invention. It is a sectional side view of the optical scanning device concerning the present invention. It is the perspective view which looked at the housing of the optical scanning device concerning the present invention from the lower part. 2 is a perspective view of a metal frame of the image forming apparatus. FIG.

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

[Image forming apparatus]
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), and the manual feed provided rotatably in the manual feed tray 4 and 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 transports the paper P, which is a recording material, along the transport path S provided in the printer main body 2, and based on the image data transmitted from a terminal (not shown) or the like. The conveyance path S is formed in a substantially L shape in 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 S. The transport path S 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. An optical scanning device (laser scanner unit) 21 according to the present invention arranged above, a toner hopper 22 containing toner for replenishment, 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 by a biasing means such as a spring with a predetermined pressure. Is formed.

  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 transport path S. A pair of paper rollers 25, 26, a plurality of vertical rib-shaped conveyance guide ribs 27 for guiding the paper P conveyed from the fixing device 9 along the conveyance path S to the conveyance roller pairs 25, 26, and the outside of the printer main body 2. The paper discharge tray 3 for loading the paper P to be discharged 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 the laser beam L based on the image data transmitted from the terminal is output from the optical scanning device 21 and irradiated onto the photosensitive drum 16, an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 16. It is formed. 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 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. 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 on which the toner image is fixed on the surface by the fixing device 9 is conveyed upward along the conveyance path S 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.

[Optical scanning device]
Next, the optical scanning device 21 according to the present invention will be described with reference to FIGS.

  2 is a plan view of the optical scanning apparatus according to the present invention with the cover removed, FIG. 3 is a side sectional view of the optical scanning apparatus, FIG. 4 is a perspective view of the optical scanning apparatus viewed from below, and FIG. FIG. 3 is a perspective view of a metal frame of a laser printer.

  As shown in FIG. 2, a laser diode 29 as a light source is attached to the resin housing 28 of the optical scanning device 21 according to the present invention. The housing 28 contains a cylindrical lens 30, a polygon mirror 31 as a deflecting means, a polygon motor 32 that rotates the mirror 31, fθ lenses 33 and 34 that are scanning lenses, a folding mirror 35, and the like. The upper surface opening of 28 is covered with a resin cover 36 as shown in FIG.

  As shown in FIG. 3, the optical scanning device 21 having the above configuration is positioned and attached to the metal frame 37 of the laser printer 1 shown in FIG. 1. However, as shown in FIG. A cylindrical positioning boss 28A is formed. Further, as shown in FIG. 5, a metal positioning pin 38 is erected at a position corresponding to the positioning boss 28A of the metal frame 37.

  By the way, in the present embodiment, as shown in FIG. 3, the positioning boss 28 </ b> A formed on the housing 28 has a bearing 39 of the polygon motor 32 and a metal positioning pin 38 erected on the metal frame 37. In opposite directions, that is, the bearing 39 of the polygon motor 32 is inserted and fitted from above and the positioning pin 38 is inserted and fitted from below, respectively, and a highly thermally conductive cushion material 40 made of Si-based resin or the like is interposed therebetween. is doing.

  Therefore, in the positioning boss 28 </ b> A formed in the housing 28, the bearing 39 of the polygon motor 32 and the positioning pin 38 are in contact with each other via the cushion material 40 having high thermal conductivity.

  Thus, in the optical scanning device 21 configured as described above, as shown in FIGS. 2 and 3, the laser beam L emitted from the laser diode 29 as the light source is a cylindrical having a refractive index only in one direction. The light passes through the lens 30 and is condensed linearly on the reflection surface of the polygon mirror 31.

  The polygon mirror 31 is rotationally driven at a high speed by a polygon motor 32. The laser beam L condensed on the reflection surface of the polygon mirror 32 is deflected and scanned by the rotation of the polygon mirror 32, and two fθ lenses 33, After passing through 34, it is folded back by a folding mirror 35 and imaged on the surface of the photosensitive drum 16 shown in FIG. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 16, and the electrostatic latent image is visualized as a toner image by the developing device 18 as described above.

  In the above, the heat generated in the polygon motor 32 of the optical scanning device 21 is conducted from the bearing 39 of the polygon motor 32 to the metal positioning pin 38 through the cushioning material 40 having high thermal conductivity, and the positioning pin 38. Since the positioning pin 38 functions as a heat sink, the rise of the ambient temperature in the housing 28 can be suppressed with a simple configuration using existing components. For this reason, it is possible to prevent a decrease in image quality due to a focal length shift due to thermal deformation of the polygon mirror 31 without causing an increase in size and cost of the optical scanning device 21, and the laser printer 1 shown in FIG. Thus, a high quality image can be stably obtained.

  In the present embodiment, since the bearing 39 of the polygon motor 32 and the positioning pin 38 are brought into contact with each other via the cushion material 40 having high thermal conductivity, the variation in the height dimension of the positioning pin 38 is the cushion material 40. It is absorbed by the elastic deformation of the material, and the effect that productivity and assemblability are improved is also obtained.

  Although the present invention has been described with respect to a mode in which the present invention is applied to a laser printer and an optical scanning device provided in the laser printer, the present invention is not limited to any other image forming apparatus including a copying machine, a facsimile, etc. Of course, the present invention can also be applied to the optical scanning device provided in the same.

1 Laser printer (image forming device)
DESCRIPTION OF SYMBOLS 2 Printer main body 3 Paper discharge tray 4 Manual feed tray 5 Paper feed roller 6 Manual paper feed part 7 Cassette paper feed part 8 Image forming part 9 Fixing device 10 Paper discharge part 11 Paper feed cassette 12 Pick roller 13 Feed roller 14 Retard roller 15 Resist Roller pair 16 Photosensitive drum 17 Charger 18 Developing device 19 Transfer roller 20 Cleaning device 21 Optical scanning device (laser scanner unit)
22 toner hopper 23 fixing roller 24 pressure roller 25, 26 discharge roller pair 27 guide rib 28 optical scanning device housing 28A housing positioning boss 29 laser diode 30 cylindrical lens 31 polygon mirror 32 polygon motor 33, 34 fθ lens 35 folding mirror 36 Cover 37 Metal frame 38 Positioning pin 39 Polygon motor bearing 40 Cushion material L Laser beam P Paper S Transport path

Claims (3)

In an optical scanning apparatus that is positioned and attached to a metal frame of an image forming apparatus, and that houses a polygon mirror that is a deflecting means and a polygon motor that rotationally drives the polygon mirror in a resin housing,
A bearing of the polygon motor and a metal positioning pin erected on the metal frame are inserted and fitted in opposite directions to a positioning boss formed in the housing, and both are brought into contact with each other. Optical scanning device.   2. The optical scanning device according to claim 1, wherein a bearing of the polygon motor and the positioning pin are brought into contact with each other via a cushion material having high thermal conductivity. An image forming apparatus comprising the optical scanning device according to claim 1.

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