JP5264625B2 - Optical scanning apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an optical scanning device that scans a beam of light and writes and forms an image, and an image forming apparatus including the same, which are used in image forming apparatuses such as printers, copying machines, and facsimiles.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic system such as a copying machine or a printer, optical scanning is performed by scanning a light beam modulated based on input image data on the surface of a photosensitive drum uniformly charged by a charging device. An image forming process in which an electrostatic latent image formed by the optical scanning device is developed into a toner image by a developing device, and the toner image is further transferred onto a recording paper and the like, and is converted into a permanent image by a fixing device. Done.

  By the way, inside the image forming apparatus using the electrophotographic process, toner used for developing the electrostatic latent image, paper dust generated by the conveyance of the paper, dust entering from the outside of the image forming apparatus, etc. are scattered and floated. doing. If these dusts enter the optical scanning apparatus and adhere to optical elements and optical members such as lenses and mirrors, a part of the optical path of the scanning light is blocked, resulting in a decrease in image quality. For this reason, various measures have been devised to improve the sealing performance of the optical scanning device and prevent the entry of dust from the outside.

  For example, in Patent Document 1, an adhesive is applied to a part or the entire surface of a lid member that covers an opening of an optical box (housing), and the optical box is sealed by attaching the lid member to the optical box. A method for preventing the intrusion of dust and the like from the air is disclosed. Patent Document 2 discloses an optical scanning device in which dust is prevented from entering by providing an elastic member between a partition wall formed in the optical box or a component in the optical box and a cover member.

JP 2002-341275 A JP 2005-309085 A

  However, in the method of Patent Document 1, although the sealing performance of the optical scanning device can be ensured, once the lid is attached and the optical box is sealed, the optical elements and optical members inside the device are replaced. It is difficult to remove the lid member again for adjustment, and if it is removed forcibly, a load is applied to the optical box, which may cause deformation or breakage of the optical box.

  Further, in the method of Patent Document 2, there are cases where an elastic member cannot be provided due to the layout of the optical scanning device. When a sponge or the like is used as the elastic member, dust generated from the sponge adheres to the optical member. There is also a possibility of adversely affecting the image. Further, a method of providing double ribs on the cover member and preventing the intrusion of dust or the like by sandwiching the wall surface of the housing between the ribs is conceivable. However, the optical member is attached to the vicinity of the upper end of the wall surface of the housing. In this case, it was difficult to secure a space for providing the rib.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an optical scanning device that is excellent in hermeticity, reliably prevents entry of dust and the like from the outside, and can be easily opened and closed, and an image forming apparatus including the same. With the goal.

  To achieve the above object, the present invention is formed on a scanning optical system that deflects and scans a surface to be scanned by a beam emitted from a light source unit, a housing that supports the scanning optical system, and an upper surface or a lower surface of the housing. A first cover member that can be opened and closed to cover the opened opening, and a second cover member that is detachably mounted with the side surface of the housing sandwiched in the vertical direction via the first cover member. It is a scanning device.

  According to the present invention, in the optical scanning device configured as described above, the second cover member is attached to and detached from the housing by elastic deformation.

  According to the present invention, in the optical scanning device configured as described above, the first cover member includes a flange portion that covers a side surface of the housing from the outside, and the second cover member includes the flange portion and an upper surface or a lower surface of the housing. It has the engaging part engaged with.

  According to the present invention, in the optical scanning device having the above configuration, the engaging portion is provided with a locking claw for restricting sliding of the second cover member in a direction away from the side surface of the housing. Yes.

  The present invention also provides an image forming apparatus on which the optical scanning device having the above-described configuration is mounted.

  According to the first configuration of the present invention, by providing the second cover member that is mounted with the side surface of the housing sandwiched in the vertical direction via the first cover member, the housing and the first cover member are provided. It is possible to suppress entry of dust and the like into the optical scanning device from the gap. In addition, since the second cover member is detachable, the opening / closing performance of the first cover member can be secured.

  According to the second configuration of the present invention, in the optical scanning device of the first configuration, the second cover member is attached and detached by elastic deformation of the second cover member, whereby the housing and the first cover member are separated. Adhesion is ensured and a gap is less likely to occur, and entry of dust and the like can be more effectively suppressed.

  According to the third configuration of the present invention, in the optical scanning device having the first or second configuration, the first cover member is provided with the flange portion that covers the side surface of the housing from the outside, and is provided on the second cover member. The second cover member can be easily mounted with the side surface of the housing sandwiched in the vertical direction via the first cover member by engaging the formed engaging portion with the flange portion and the upper surface or the lower surface of the housing. Can do. Further, the second cover member and the first cover member can be easily removed simply by releasing the engagement of the engaging portion.

  Further, according to the fourth configuration of the present invention, in the optical scanning device of the third configuration described above, the engagement that restricts the sliding in the direction away from the side surface of the housing at the engaging portion of the second cover member. By providing the claw, it is possible to prevent the second cover member from being detached due to vibration or impact without using a screw or the like. Therefore, the first cover member can be prevented from being lifted and the strength of the optical scanning device can be increased.

  Further, according to the fifth configuration of the present invention, the lens in the optical scanning device is mounted by mounting the optical scanning device having any one of the first to fourth configurations on an image forming apparatus such as a copying machine or a printer. Thus, the image forming apparatus is less likely to cause image quality degradation due to adhesion of dust to optical elements such as mirrors and optical members.

Schematic showing the overall configuration of a tandem color image forming apparatus equipped with the optical scanning device of the present invention The top view which shows the internal structure of the optical scanner of this invention Side surface sectional drawing which shows the internal structure of the optical scanning device of this invention External perspective view of the optical scanning device of the present invention The perspective view which looked at the side cover from the back side Partial sectional view showing the housing with only the top cover attached Partial sectional view showing a state in which a top cover and a side cover are mounted on the housing The fragmentary sectional view which shows the engagement state of a side cover, a housing, and an upper surface cover Enlarged view of the engaging portion in FIG. Partial sectional view showing the joining state with the upper surface cover on the left and right side surfaces of the housing

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an image forming apparatus equipped with the optical scanning device of the present invention. Here, a tandem color image forming apparatus is shown. In the main body of the color image forming apparatus 100, four image forming portions Pa, Pb, Pc, and Pd are sequentially arranged from the upstream side in the transport direction (the right side in FIG. 1). These image forming portions Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow, and black), and cyan, magenta, and yellow are respectively performed by charging, exposure, development, and transfer processes. And a black image are sequentially formed.

  The image forming portions Pa to Pd are provided with photosensitive drums 1a, 1b, 1c, and 1d that carry visible images (toner images) of the respective colors, and are further driven by a driving unit (not shown). The intermediate transfer belt 8 that rotates clockwise is provided adjacent to the image forming portions Pa to Pd. The toner images formed on the photosensitive drums 1a to 1d are sequentially transferred onto the intermediate transfer belt 8 that moves while being in contact with the photosensitive drums 1a to 1d. The image is transferred onto P at a time, and further fixed on the transfer paper P in the fixing unit 7 and then discharged from the apparatus main body. An image forming process for each of the photosensitive drums 1a to 1d is executed while rotating the photosensitive drums 1a to 1d counterclockwise in FIG.

  The transfer paper P onto which the toner image is transferred is accommodated in a paper cassette 16 at the lower part of the apparatus, and is conveyed to the secondary transfer roller 9 via a paper feed roller 12a and a registration roller pair 12b. A sheet made of a dielectric resin is used for the intermediate transfer belt 8, and a belt in which both ends thereof are overlapped and joined to form an endless shape, or a belt without a seam (seamless) is used.

  Next, the image forming units Pa to Pd will be described. Around the photosensitive drums 1a to 1d that are rotatably arranged, there are chargers 2a, 2b, 2c, and 2d for charging the photosensitive drums 1a to 1d, and image information to the photosensitive drums 1a to 1d. Removes the developer (toner) remaining on the photosensitive drums 1a to 1d, the optical scanning device 4 that exposes the toner, the developing units 3a, 3b, 3c, and 3d that form toner images on the photosensitive drums 1a to 1d. Cleaning parts 5a, 5b, 5c and 5d are provided.

  When the start of image formation is input by the user, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the chargers 2a to 2d, and then the laser beam is irradiated by the optical scanning device 4 to each photosensitive drum. Electrostatic latent images corresponding to image signals are formed on 1a to 1d. Each of the developing units 3a to 3d is filled with a predetermined amount of cyan, magenta, yellow, and black toner by a replenishing device (not shown). The toner is supplied onto the photosensitive drums 1 a to 1 d by the developing units 3 a to 3 d and electrostatically attached to the toner image corresponding to the electrostatic latent image formed by exposure from the optical scanning device 4. Is formed.

  After an electric field is applied to the intermediate transfer belt 8 at a predetermined transfer voltage, the cyan, magenta, yellow, and black toner images on the photosensitive drums 1a to 1d are transferred to the intermediate transfer belt 8 by the primary transfer rollers 6a to 6d. Transcribed above. These four color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. Thereafter, the toner remaining on the surfaces of the photosensitive drums 1a to 1d is removed by the cleaning units 5a to 5d in preparation for the subsequent formation of a new electrostatic latent image.

  The intermediate transfer belt 8 is stretched between an upstream conveyance roller 10 and a downstream drive roller 11, and the intermediate transfer belt 8 rotates clockwise as the drive roller 11 is rotated by a drive motor (not shown). When the rotation starts, the transfer paper P is conveyed from the registration roller pair 12b to a transfer roller 9 provided adjacent to the intermediate transfer belt 8 at a predetermined timing, and a full-color image is transferred. The transfer paper P onto which the toner image is transferred is conveyed to the fixing unit 7.

  The transfer paper P conveyed to the fixing unit 7 is heated and pressurized by the fixing roller pair 13 so that the toner image is fixed on the surface of the transfer paper P, and a predetermined full color image is formed. The transfer paper P on which the full-color image is formed is distributed in the transport direction by the branching portion 14 that branches in a plurality of directions. When an image is formed on only one side of the transfer paper P, the image is directly discharged onto the discharge tray 17 by the discharge roller pair 15.

  On the other hand, when images are to be formed on both sides of the transfer paper P, the transfer paper P that has passed through the fixing unit 7 is distributed to the paper transport path 18 by the branching unit 14, and is transferred again to the transfer roller 9 with the image surface reversed. Be transported. Then, the next image formed on the intermediate transfer belt 8 is transferred to the surface of the transfer paper P on which the image is not formed by the transfer roller 9 and conveyed to the fixing unit 7 to fix the toner image, and then discharged. It is discharged to the tray 17.

  FIG. 2 is a plan view showing the internal configuration of the optical scanning device of the present invention, and FIG. 3 is a side sectional view (cross section AA ′ in FIG. 2) showing the internal configuration of the optical scanning device. In FIG. 2, the description of the plane mirrors 46a to 46d is omitted. As shown in FIGS. 2 and 3, the optical scanning device 4 has a housing 48, and a polygon mirror 44 is disposed at a substantially central portion of the bottom surface 48 a of the housing 48. In this embodiment, the polygon mirror 44 is composed of a regular hexagonal rotary polygon mirror having six deflection surfaces (reflection surfaces) 44 a on the side surface, and is rotated by the polygon motor 50 at a predetermined speed.

  In addition, four light source portions 40a to 40d are arranged in the vicinity of the front side (lower side in FIG. 2) end portion of the housing 48. Although illustrated as one in FIG. 2, the light source units 40a and 40b and 40c and 40d overlap in the sub-scanning direction (paper surface direction). The light source units 40a to 40d are configured by LDs (laser diodes), and emit light beams (laser beams) D1 to D4 that are optically modulated based on image signals.

  Between the light source units 40a to 40d and the polygon mirror 44, four collimator lenses 41 provided corresponding to the respective light source units 40a to 40d, and beam lights D1 to D4 that have passed through the collimator lens 41 are given beams. Aperture 51 having a width, two cylindrical lenses 42 through which the beam lights D1 and D2, D3 and D4 pass after passing through the aperture 51, and beam lights D1 to D4 which have passed through the cylindrical lens 42 are converted into the polygon mirror 44 Two folding mirrors 43 led to the deflection surface 44a are arranged. Although shown as one in FIG. 2, the collimator lens 41 and the aperture 51 corresponding to the light source units 40a and 40b and 40c and 40d overlap each other in the sub-scanning direction.

  The collimator lens 41 converts the light beams D1 to D4 emitted from the light source sections 40a to 40d into substantially parallel light beams, and the cylindrical lens 42 has a predetermined refractive power only in the sub-scanning direction (vertical direction in FIG. 3). It is. Further, in the housing 48, the first scanning lenses 45a and 45b and the second scanning lenses 47a, 47b, 47c, and 47d are arranged to face each other across the polygon mirror 44. The first scanning lenses 45a and 45b and the second scanning lenses 47a to 47d have fθ characteristics, and the light beams D1 to D4 deflected and reflected by the polygon mirror 44 are reflected on the photosensitive drums 1a to 1d (see FIG. 1). To form an image. Further, plane mirrors 46a to 46c are arranged on the optical paths of the respective beam lights D1 to D4 from the polygon mirror 44 to the photosensitive drums 1a to 1d (see FIG. 1).

  The scanning operation of the light beams D1 and D2 by the optical scanning device 4 configured as described above will be described. First, the light beams D1 and D2 emitted from the light source units 40a and 40b are made into a substantially parallel light beam by the collimator lens 41 and have a predetermined optical path width by the aperture 51. Next, the light beams D 1 and D 2 that have become substantially parallel light beams are incident on the cylindrical lens 42. The light beams D1 and D2 incident on the cylindrical lens 42 are in the state of a parallel light beam in the main scanning section as it is, converged and emitted in the sub-scanning direction, and are formed as a line image on the deflection surface 44a of the polygon mirror 44. . At this time, in order to easily separate the optical paths of the two light beams D1 and D2 deflected by the polygon mirror 44, the light beams D1 and D2 are incident on the deflecting surface 44a at different angles in the sub-scanning direction. Is configured to do.

  The light beams D1 and D2 incident on the polygon mirror 44 are deflected at a constant angular velocity by the polygon mirror 44 and then deflected at a constant velocity by the first scanning lens 45a. The light beams D1 and D2 that have passed through the first scanning lens 45a are folded a predetermined number of times by the plane mirrors 46a and 46b disposed in the respective optical paths, the light beam D1 is transmitted to the second scanning lens 47a, and the light beam D2 is the second light beam D2. The light enters the scanning lens 47b and is deflected at a constant speed by the second scanning lenses 47a and 47b. The beam beams D1 and D2 deflected at the same speed are folded back by the final plane mirror 47c disposed in the respective optical paths, and passed through the windows 60a and 60b formed on the upper surface cover 60 covering the opening of the housing 48. The light passes through and is distributed to the photosensitive drums 1a and 1b.

  Similarly, the light beams D3 and D4 emitted from the light source sections 40c and 40d pass through the collimator lens 41 and the cylindrical lens 42b, are deflected at an equal angle by the polygon mirror 44, and are deflected at a constant speed by the first scanning lens 45b. The Then, after being folded back by the plane mirrors 46a and 46b, the beam light D3 is deflected at a constant speed by the second scanning lens 47c, and the beam light D4 is deflected by the second scanning lens 47d, respectively. Further, the light is folded by the final flat mirror 46c and distributed to the photosensitive drums 1c and 1d from the windows 60c and 60d formed on the upper surface cover 60.

  FIG. 4 is an external perspective view of the optical scanning device of the present invention. Transparent plates for preventing entry of dust and the like are fitted into the four window portions 60 a to 60 d formed on the upper surface cover 60. Further, side covers 61 a and 61 b are attached to the front and rear sides of the housing 48.

  FIG. 5 is a perspective view of the side cover 61a as viewed from the back side. Engaging portions 63a are integrally formed at four locations on the upper end of the side cover 61a, and engaging portions 63b are integrally formed at four locations on the lower end. Further, a boss 65 that fits into a positioning hole (not shown) formed in the side surface of the housing 48 is projected from the center portion. Hereinafter, the mounting method and mounting state of the side cover 61a to the housing 48 will be described. However, the configuration of the side cover 61b, the mounting method to the housing 48, and the mounting state are basically the same, and description thereof will be omitted.

  As a mounting procedure of the side cover 61 a, the opening of the housing 48 is closed by the top cover 60, and then the side cover 61 a is pressed against the housing 48 with the boss 65 aligned with the positioning hole on the side of the housing 48. Then, the engaging portion 63a of the side cover 61a is elastically deformed to engage with a flange portion 68 (see FIG. 8) formed on the edge of the upper surface cover 60, and the engaging portion 63b is elastically deformed to deform the bottom surface of the housing 48. Engage with.

  FIG. 6 is a partial cross-sectional view showing a state where only the upper surface cover is attached to the housing, and FIG. 7 is a partial cross-sectional view showing a state where the upper surface cover and the side cover are attached to the housing. As shown in FIG. 6, since the parts such as the flat mirror 46c and the mirror preparation member 67 are attached to the side surface of the housing 48, double ribs 73a and 73b (see FIG. 10) are provided on the top cover 60 as a measure against dust. There is no space for providing an elastic member, and dust or the like easily flows into the apparatus through the gap 70a between the housing 48 and the upper surface cover 60 only by attaching the upper surface cover 60.

  Therefore, in the present invention, as shown in FIG. 7, a side cover 61 a that covers the gap 70 a between the housing 48 and the upper surface cover 60 is attached. With this configuration, in order for dust or the like to enter the inside of the apparatus, it is necessary to pass through the gap 70b between the top cover 60 and the side cover 61a and further through the gap 70a between the housing 48 and the top cover 60. Therefore, it becomes a structure in which dust does not easily flow in compared with the case where only the upper surface cover 60 is attached.

  FIG. 8 is a partial cross-sectional view including the engaging portion 63a in a state where the upper surface cover and the side surface cover are attached to the housing, and FIG. 9 is an enlarged view showing an engaged state of the engaging portion 63a in FIG. As shown in FIG. 8, the side cover 61a is configured to sandwich the housing 48 and the upper surface cover 60 from above and below by the restoring force of the engaging portions 63a and 63b (see FIG. 5), and thus holds the upper surface cover 60 in the closed state. be able to. In addition, the adhesion between the housing 48 and the upper surface cover 60 is ensured, and the gap 70a is less likely to occur, so that the inflow of dust and the like can be effectively suppressed.

  Further, as shown in FIG. 9, a locking claw 71 is formed at the tip of the engaging portion 63 a and engages with a protrusion 69 protruding from the flange portion 68. A similar locking claw 71 is also formed on the engaging portion 63 b and engages with an engaging hole formed on the bottom surface of the housing 48. With this configuration, sliding in the direction in which the side cover 61a moves away from the housing 48 (arrow B direction) is restricted. Therefore, the side cover 61a is dropped or the top cover 60 is lifted by vibration or impact without using screws or the like. And the strength of the optical scanning device 4 can be increased.

  Further, since the side cover 61a can be easily removed by simply disengaging the engaging portions 63a and 63b, the upper surface cover can be used when adjusting or replacing optical elements or optical members in the housing 48. 60 can be easily opened and closed.

  In this embodiment, the side covers 61a and 61b are attached to only two locations on the front side and the rear side (upper and lower sides in FIG. 2) of the housing 48, and the right side and left side of the housing 48 (left and right in FIG. 2). In the side surface, as shown in FIG. 10, double ribs 73 a and 73 b are provided on the edge of the upper surface cover 60 to sandwich the side surface of the housing 48.

  However, for example, when there is a space for providing double ribs on the rear side of the housing 48, the side cover 61a may be attached only to the front side. In addition, when there is no space for providing double ribs on the right side surface and the left side surface of the housing 48, the side covers may be attached to all four side surfaces of the housing 48.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the optical scanning device 4 shown in the above embodiment is configured to emit light beams D1 to D4 from the upper surface of the housing 48 and irradiate the upper photosensitive drums 1a to 1d, but the photosensitive drums 1a to 1d. May be arranged below the optical scanning device 4 and emit the light beams D1 to D4 from the lower surface of the housing 48. The same applies to the case where the lower surface cover is removable instead of the upper surface cover 60.

  In the optical scanning device 4 shown in the above embodiment, the polygon mirror 44 is disposed substantially at the center of the housing 48 to deflect the light beams D1 and D2, D3 and D4 in opposite directions. Alternatively, a polygon mirror 44 may be disposed at one end of the beam and separated in the sub-scanning direction while deflecting the light beams D1 to D4 in the same direction.

  The present invention is not limited to the multi-beam optical scanning device, but can be applied to a single-beam optical scanning device mounted on a monochrome copying machine or a monochrome printer.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical scanning device used for image forming apparatuses such as printers, copiers, and facsimiles, which scans light beams and writes and forms an image.

DESCRIPTION OF SYMBOLS 4 Optical scanning device 40a-40d Light source part 41 Collimator lens 42 Cylindrical lens 44 Polygon mirror 45a, 45b 1st scanning lens 46a-46c Planar mirror 47a-47d 2nd scanning lens 48 Housing 60 Upper surface cover (1st cover member)
61a, 61b Side cover (second cover member)
63a, 63b engaging portion 68 flange portion 69 projection 70a, 70b gap 71 locking claw 73a, 73b rib 100 image forming apparatus D1-D4 beam light

Claims (5)

A scanning optical system that deflects and scans the surface to be scanned by a beam emitted from the light source unit;
A housing for supporting the scanning optical system;
A first cover member that can be opened and closed to cover an opening formed on the upper surface or the lower surface of the housing;
A second cover member that is detachably mounted in a state where the side surface of the housing is sandwiched in the vertical direction together with the edge of the first cover member;
An optical scanning device.   The optical scanning device according to claim 1, wherein the second cover member is attached to and detached from the housing by elastic deformation.   The first cover member has a flange portion that covers the side surface of the housing from the outside, and the second cover member has an engagement portion that engages with the flange portion and an upper surface or a lower surface of the housing. The optical scanning device according to claim 1 or 2.   The optical scanning device according to claim 3, wherein a locking claw that restricts sliding of the second cover member in a direction away from a side surface of the housing is provided in the engaging portion.   An image forming apparatus on which the optical scanning device according to claim 1 is mounted.

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