JP6245146B2 - Optical scanning device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to an optical scanning device that is used in an image forming apparatus such as a printer, a copying machine, and a facsimile machine, and scans a beam of light to write and form an image.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method such as a copying machine or a printer, a beam light (laser light) modulated based on input image data is applied to the surface of a photosensitive drum uniformly charged by a charging device. An optical scanning device that irradiates and scans is provided. An electrostatic latent image formed by the optical scanning device is developed into a toner image by a developing device, and further, the toner image is transferred onto a recording paper or the like, and then permanently fixed by a fixing device. An image forming process to form an image is performed.

  Such an optical scanning device includes a light source unit such as an LD (laser diode) and optical members such as a polygon mirror, a scanning lens, and a mirror in a housing, and each optical member is accurately positioned at a predetermined position of the housing. Need to be placed.

  As a method for positioning the scanning lens, for example, in Patent Document 1, the imaging lens (scanning lens) can be in contact with the imaging lens at three points, that is, both ends in the main scanning direction and an intermediate portion between the both ends. There has been proposed an optical scanning device including an abutting member and an urging means for urging the imaging lens toward the abutting member.

JP 2000-111182 A

  By the way, the photosensitive drum includes an OPC drum having an organic photosensitive layer (OPC) as a photosensitive layer and an a-Si drum having an amorphous silicon (a-Si) photosensitive layer. The wavelength of the LD used for writing the electrostatic latent image is different between the OPC drum and the a-Si drum.

  For this reason, when using LDs having different wavelengths without changing the arrangement of optical components such as scanning lenses, an expensive scanning lens having a performance sufficient to allow the difference in wavelengths is required. Further, when an inexpensive scanning lens is arranged at different positions in consideration of the cost of the scanning lens, it is necessary to prepare a plurality of types of housings for arranging optical components. As a result, the number of parts increases and parts management becomes complicated, which is disadvantageous in terms of cost.

  In view of the above problems, the present invention includes an optical scanning device capable of arranging a scanning lens at an optimum position according to the wavelength of the light source when a common scanning lens is used for light sources having different wavelengths, and the same. Another object of the present invention is to provide an image forming apparatus.

  In order to achieve the above object, the present invention is an optical scanning device including a light source unit, an aperture, a polygon mirror, a scanning lens, and a housing. The light source unit emits beam light. The aperture shapes the light beam emitted from the light source unit. The polygon mirror deflects and scans the light beam that has passed through the aperture. The scanning lens is disposed in the optical path of the beam light deflected by the polygon mirror. The housing supports the light source unit, the aperture, the polygon mirror, and the scanning lens. The housing is capable of selectively mounting a plurality of types of light source units having different light beam wavelengths and a plurality of types of apertures corresponding to the mounted light source unit, and the scanning lens is provided in the plurality of types of apertures. The lens positioning portion selectively positions the different positions of the housing.

  According to the first configuration of the present invention, when a plurality of types of light source units having different wavelengths are used, an aperture corresponding to the type of the light source unit to be mounted is selectively attached, and the lens positioning provided in the aperture The portion selectively positions the scanning lens at a different position on the housing. Accordingly, it is possible to attach the scanning lens with high accuracy to a predetermined position of the housing corresponding to the wavelength of the light source unit using a common scanning lens and a common housing. As a result, an optical scanning device capable of scanning the surface to be scanned with high accuracy without using an expensive scanning lens or a plurality of types of housings is obtained.

1 is a schematic diagram showing an overall configuration of an image forming apparatus 100 equipped with optical scanning devices 4a and 4b according to an embodiment of the present invention. The perspective view which shows the internal structure of the optical scanning device 4a Side sectional view schematically showing the internal structure of the optical scanning device 4a The perspective view which looked at the 2nd apertures 47a and 47b used for optical scanning device 4a of the present invention from the surface side The perspective view which looked at the 2nd aperture 47a and 47b from the back side. The perspective view which shows the state which mounted | wore the housing main body 41a with the 2nd aperture 48b, and has arrange | positioned the scanning lens 48b. The top view which shows the state which mounted | wore the housing main body 41a with the 2nd aperture 48b, and has arrange | positioned the scanning lens 48b. FIG. 7 is an enlarged view of a contact portion between the scanning lens 48a and the lens positioning portion 50 of the second aperture 48a as viewed from the back side of the second aperture 47b, and shows a state in which the scanning lens 48a is positioned in the longitudinal direction. It is the enlarged view which looked at the contact part of the scanning lens 48a and the lens positioning part 50 of the 2nd aperture 48a from the back surface side of the 2nd aperture 47b, and shows the state which the scanning lens 48a was positioned to the longitudinal direction and the thickness direction. Figure

  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 100 on which optical scanning devices 4a and 4b of the present invention are mounted. Here, a tandem color image forming apparatus is shown. In the main body of the 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.

  These image forming portions Pa to Pd are provided with photosensitive drums 1a, 1b, 1c and 1d which carry visible images (toner images) of the respective colors, and are further illustrated by a driving means (not shown). 1, an intermediate transfer belt 8 that rotates in the clockwise direction is provided adjacent to each of the image forming portions Pa to Pd. The toner images formed on the photosensitive drums 1 a to 1 d are sequentially transferred onto the intermediate transfer belt 8 that moves while contacting the photosensitive drums 1 a to 1 d, and then transferred onto the transfer paper at the secondary transfer roller 9. 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 in the counterclockwise direction 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 the paper feed roller 12a and the registration roller pair 12b. A sheet made of dielectric resin is used for the intermediate transfer belt 8, and a (seamless) belt mainly having no seam is used.

  Next, the image forming units Pa to Pd will be described. Around the photosensitive drums 1a to 1d 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. Scanning devices 4a and 4b for exposing the toner, developing units 3a, 3b, 3c and 3d for forming toner images on the photosensitive drums 1a to 1d, and a developer (toner) remaining on the photosensitive drums 1a to 1d. Cleaning portions 5a, 5b, 5c, and 5d are provided for removing water.

  When the start of image formation is input by the user, the surfaces of the photosensitive drums 1a to 1d are first uniformly charged by the chargers 2a to 2d, and then the laser beams are irradiated by the optical scanning devices 4a and 4b. Electrostatic latent images corresponding to image signals are formed on the body drums 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). This toner is supplied onto the photosensitive drums 1a to 1d by the developing units 3a to 3d and electrostatically attached thereto, so that the toner corresponds to the electrostatic latent image formed by exposure from the optical scanning devices 4a and 4b. A toner image is formed.

  After an electric field is applied between the primary transfer rollers 6a to 6d and the intermediate transfer belt 8 at a predetermined transfer voltage, cyan, magenta, yellow, and yellow on the photosensitive drums 1a to 1d are applied by the primary transfer rollers 6a to 6d. The black toner image is transferred onto the intermediate transfer belt 8. 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 transport 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 rotation in the direction starts, the transfer paper P is conveyed from the registration roller pair 12b to the secondary transfer roller 9 provided adjacent to the intermediate transfer belt 8 at a predetermined timing, and the full color formed on the intermediate transfer belt 8 is formed. The 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 pressed by the fixing roller pair 13 so that the toner image is fixed on the surface of the transfer paper P to be a permanent image. The transfer paper P on which the full-color image is formed in the fixing unit 7 is distributed in the transport direction by the branching unit 14 that branches in a plurality of directions. When an image is formed on only one side of the transfer paper P, it is discharged as it is onto the discharge tray 17 by the discharge roller pair 15.

  On the other hand, when images are formed on both sides of the transfer paper P, most of the transfer paper P that has passed through the fixing unit 7 is discharged to the discharge tray 17, and then the discharge roller pair 15 is reversely rotated to be drawn into the apparatus again. . The drawn transfer paper P is distributed to the reversal conveyance path 18 by the branching section 14 and re-conveyed to the secondary transfer roller 9 with the image surface reversed. Then, after the next image formed on the intermediate transfer belt 8 is transferred by the secondary transfer roller 9 to the surface of the transfer paper P where the image is not formed, and conveyed to the fixing unit 7 to fix the toner image. , And discharged to the discharge tray 17.

  FIG. 2 is a perspective view showing the internal configuration of the optical scanning device 4a of the present invention, and FIG. 3 is a side sectional view of the optical scanning device 4a (a cross-sectional view taken along the line AA 'in FIG. 2). 2 shows a state in which the upper lid 41b is removed so that the inside of the optical scanning device 4a can be seen. Although the configuration of the optical scanning device 4a is described here, the configuration of the optical scanning device 4b is exactly the same.

  As shown in FIGS. 2 and 3, the optical scanning device 4a has a housing 41 composed of a housing main body 41a and an upper lid 41b, and a polygon mirror 42 is disposed at a substantially central portion of the housing main body 41a. . In the present embodiment, the polygon mirror 42 is composed of a regular hexagonal rotary polygon mirror having six deflection surfaces (reflection surfaces) on the side surface, and is rotated by the polygon motor 51 at a predetermined speed. The polygon motor 51 is fitted in a motor positioning hole 52 formed on the bottom surface of the housing body 41a.

  In addition, two light source portions 43a and 43b are disposed on the side wall on the front side (the left front side in FIG. 2) of the housing body 41a. The light source units 43a and 43b are constituted by LDs (laser diodes), and emit light beams (laser beams) D1 and D2 that are optically modulated based on image signals.

  Between the light source units 43a and 43b and the polygon mirror 42, two collimator lenses 44a and 44b provided corresponding to the light source units 43a and 43b, and the beam light D1 that has passed through the collimator lenses 44a and 44b. , D2 each having a predetermined optical path width, two cylindrical lenses 46a and 46b through which the beam lights D1 and D2 pass after passing through the first apertures 45a and 45b and the first apertures 45a and 45b, respectively, and the cylindrical Second apertures 47a and 47b are provided in which the light beams D1 and D2 that have passed through the lenses 46a and 46b respectively have predetermined optical path widths.

  The collimator lenses 44a and 44b make the light beams D1 and D2 emitted from the light source units 43a and 43b into substantially parallel beams, respectively. The cylindrical lenses 46a and 46b are predetermined only in the sub-scanning direction (vertical direction in FIG. 3). It has a refractive power of In the housing main body 41a, scanning lenses 48a and 48b are arranged opposite to each other with the polygon mirror 42 interposed therebetween. The scanning lenses 48a and 48b have fθ characteristics, and form an image of the beam light deflected and reflected by the polygon mirror 42 on the photosensitive drums 1a to 1d (see FIG. 1). Further, three plane mirrors 49a and 49b are arranged on the optical paths of the respective beam lights D1 and D2 from the scanning lenses 48a and 48b to the photosensitive drums 1a to 1d (see FIG. 1).

  The beam scanning operation by the optical scanning device 4a configured as described above will be described. First, as shown in FIG. 2, the light beams D1 and D2 emitted from the light source units 43a and 43b are made into substantially parallel light beams by the collimator lenses 44a and 44b, and have a predetermined optical path width by the first apertures 45a and 45b. Is done. Next, the beam lights D1 and D2 that have become substantially parallel light beams are incident on the cylindrical lenses 46a and 46b. The light beams D1 and D2 incident on the cylindrical lenses 46a and 46b are in the state of parallel light beams as they are in the main scanning section and converged and emitted in the sub-scanning direction. After that, a line image is formed on the deflection surface of the polygon mirror 42.

  The light beams D1 and D2 incident on the polygon mirror 42 are deflected at a constant angular velocity by the polygon mirror 42 and then deflected at a constant velocity by the scanning lenses 48a and 48b. As shown in FIG. 3, the light beams D1 and D2 that have passed through the scanning lenses 48a and 48b are folded a predetermined number of times (here, three times) by the plane mirrors 49a and 49b arranged in the respective optical paths, and formed on the upper lid 41b. The light is distributed to the photosensitive drums 1a and 1b through the window portion 54 formed. Similarly, the light beam emitted from the optical scanning device 4b is distributed to the photosensitive drums 1c and 1d.

  4 and 5 are perspective views of the second apertures 47a and 47b used in the optical scanning devices 4a and 4b of the present invention, respectively, as viewed from the front side and the back side. The second apertures 47a and 47b include a lens positioning unit 50 that positions the scanning lenses 48a and 48b, an opening 55 that uses the light beams D1 and D2 that have passed through the cylindrical lenses 46a and 46 as predetermined optical path widths, and a housing. Boss portions 56a and 56b inserted into positioning holes 53a and 53b (see FIG. 6) of the main body 41a.

  A first regulating surface 61a and a second regulating surface 61b for regulating the positions of the scanning lenses 48a and 48b are formed on the inner wall surface of the lens positioning unit 50. The second apertures 47a and 47b are prepared in a plurality of types in which the dimensions of the opening 55 and the shapes of the first and second regulating surfaces 61a and 61b of the lens positioning unit 50 are different depending on the wavelength of the LD used as the light source units 43a and 43b. Has been.

  Hereinafter, a manufacturing method (assembly procedure) of the optical scanning devices 4a and 4b according to the embodiment of the present invention will be described. Here, the assembly of the optical scanning device 4a will be described as an example, but the assembly of the optical scanning device 4b is exactly the same.

  First, an adhesive is applied to a position for fixing the scanning lenses 48a and 48b on the bottom surface of the housing main body 41a. As the adhesive, an ultraviolet (UV) curable adhesive is used.

  Next, the boss portions 56a and 56b are inserted into the positioning holes 53a and 53b (see FIG. 6) formed in the bottom surface of the housing main body 41a to fix the second apertures 47a and 47b.

  After the second apertures 47a and 47b are fixed, the scanning lenses 48a and 48b are positioned. The scanning lenses 48a and 48b are common lenses even when the wavelengths of the LDs used as the light source units 43a and 43b are different. By changing the arrangement of the scanning lenses 48a and 48b with respect to the housing main body 41a, the light source units 43a and 43b having different wavelengths are used. 43b can also be supported.

  FIGS. 6 and 7 are a perspective view and a plan view, respectively, showing a state in which the second aperture 47b is fixed to the housing body 41a and the scanning lens 48b is arranged. FIGS. It is the enlarged view which looked at the contact part with the aperture 47b from the back surface side of the 2nd aperture 47b. 8 shows a state in which the scanning lens 48a is positioned in the longitudinal direction (vertical direction in FIG. 7), and FIG. 9 shows a state in which the scanning lens 48a is positioned in the longitudinal direction and the thickness direction (horizontal direction in FIG. 7). Is shown.

  As shown in FIGS. 6 and 7, the scanning lens 48 b is placed from the inner side of the lens positioning portion 50 in the region where the adhesive of the housing body 41 a is applied. At this time, since the adhesive is not cured, the scanning lens 48b is movable with respect to the housing body 41a.

  Then, as shown in FIG. 8, the end surface 60 a in the longitudinal direction of the scanning lens 48 b is brought into contact with the first restriction surface 61 a of the lens positioning portion 50. As a result, the scanning lens 48b is positioned in the longitudinal direction (vertical direction in FIG. 7).

  Further, by sliding the scanning lens 48b in the arrow direction from the state of FIG. 8, as shown in FIG. 9, two side surfaces 60b in the vicinity of both ends in the longitudinal direction of the scanning lens 48b orthogonal to the end surface 60a are It is made to contact | abut to the 2nd 2nd regulation surface 61b of two places of the positioning part 50, respectively. Thereby, positioning of the scanning lens 48a in the longitudinal direction and the thickness direction (left-right direction in FIG. 7) is performed. As described above, the scanning lens 48b is positioned in the horizontal direction with respect to the housing body 41a. The scanning lens 48b is positioned in the same manner with respect to the housing body 41a.

  With the scanning lenses 48a and 48b positioned, the adhesive is cured by irradiating ultraviolet rays (UV), and the scanning lenses 48a and 48b are fixed to the housing body 41a. In this manner, the attachment of the scanning lenses 48a and 48b to the housing body 41a is completed.

  Thereafter, the polygon motor 51 is fitted into the motor positioning hole 52, and the polygon mirror 42 is attached to the housing body 41a. Further, the collimator lenses 44a and 44b, the first apertures 45a and 45b, the cylindrical lenses 46a and 46b, and the like are attached to predetermined positions of the housing body 41a. Finally, the light source parts 43a and 43b are attached to the side wall of the housing body 41a, the light source parts 43a and 43b are finely adjusted to adjust the optical path of the beam light, and then the upper lid 41b is attached to assemble the optical scanning device 4a. To complete.

  According to the optical scanning devices 4a and 4b of the present invention described above, when a plurality of types of light source units 43a and 43b having different wavelengths are used, the common scanning lenses 48a and 48b and the common housing 41 are used. The scanning lenses 48a and 48b can be accurately attached to predetermined positions of the housing 41 corresponding to the wavelengths of 43a and 43b. As a result, the optical scanning devices 4a and 4b that can scan the surface to be scanned with high accuracy can be manufactured easily and at low cost without using an expensive scanning lens or a plurality of types of housings. Further, by mounting the optical scanning devices 4a and 4b on the image forming apparatus 100, high-quality image formation is possible.

  Further, by forming the lens positioning portion 50 integrally with the second apertures 47a and 47b, it is not necessary to separately attach a lens positioning member to the housing main body 41a, and the number of parts and assembly man-hours can be reduced.

  The second apertures 47a and 47b have different shapes according to the plurality of types of light source units 43a and 43b, and scanning according to the types of the second apertures 47a and 47b, that is, the wavelengths of the light source units 43a and 43b. The lenses 48a and 48b can be positioned. Accordingly, it is possible to prevent an erroneous attachment position of the scanning lenses 48a and 48b and prevent the second apertures 47a and 47b from being erroneously attached.

  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, in the optical scanning devices 4a and 4b shown in the above embodiment, the beam light that has passed through the second apertures 47a and 47b is directly incident on the polygon mirror 42. However, the second apertures 47a and 47b and the polygon mirror 42 The structure which provides a folding mirror in the optical path in between may be sufficient. The optical scanning devices 4a and 4b have the first apertures 45a and 45b and the second apertures 47a and 47b. However, the optical scanning devices 4a and 4b may have only the second apertures 47a and 47b.

  In the above embodiment, the two-beam type optical scanning devices 4a and 4b including the two light source units 43a and 43b have been described. However, the present invention is not limited to the two-beam type optical scanning device, and four light source units are provided. The present invention can be applied in exactly the same manner to the four-beam type optical scanning device provided and the single-beam type optical scanning device mounted in a monochrome copying machine or monochrome printer.

  INDUSTRIAL APPLICABILITY The present invention can be used in an optical scanning apparatus that is used in image forming apparatuses such as printers, copiers, and facsimiles and that scans light beams to write and form images. By using the present invention, when a common scanning lens is used for light sources having different wavelengths, it is possible to provide an optical scanning device capable of arranging the scanning lens at an optimum position corresponding to the wavelength of the light source. .

Pa to Pd Image forming units 1a to 1d Photosensitive drum (scanned surface)
4a, 4b Optical scanning device 41 Housing 41a Housing body 41b Upper lid 42 Polygon mirrors 43a, 43b Light source portions 44a, 44b Collimator lenses 45a, 45b First apertures 46a, 46b Cylindrical lenses 47a, 47b Second apertures 48a, 48b Scanning lens 50 Lens positioning part 53a, 53b Positioning hole 55 Opening part 56a, 56b Boss part 61a First regulating surface 61b Second regulating surface 100 Image forming apparatus

Claims (4)

A light source unit for emitting beam light;
An aperture for shaping the light beam emitted from the light source unit;
A polygon mirror that deflects and scans the light beam that has passed through the aperture;
A scanning lens disposed in the optical path of the beam light deflected by the polygon mirror;
A housing that supports the light source, aperture, polygon mirror, and scanning lens;
In an optical scanning device comprising:
The housing is capable of selectively mounting a plurality of types of light source units having different wavelengths of light beams and a plurality of types of apertures corresponding to the mounted light source units,
The optical scanning device, wherein the scanning lens is selectively positioned at different positions of the housing by lens positioning portions provided in a plurality of types of the apertures.   The lens positioning portion includes a first restriction surface that abuts on an end surface in the longitudinal direction of the scanning lens, and a second restriction surface that abuts on a side surface in the thickness direction of the scanning lens orthogonal to the end surface. The optical scanning device according to claim 1.   3. The optical scanning device according to claim 2, wherein the second restriction surface is formed at two positions of the lens positioning portion that abuts on side surfaces in the vicinity of both ends in the longitudinal direction of the scanning lens.   An image forming apparatus on which the optical scanning device according to claim 1 is mounted.

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