JP4476192B2 - Lens unit adjustment mechanism, optical scanning device and image forming apparatus provided with lens unit adjustment mechanism - Google Patents

Description

  The present invention relates to a lens unit, an optical scanning device including the lens unit, and an image forming apparatus including the optical scanning device, and more specifically, for example, an electrophotographic image such as a digital copying machine, a printer, or a facsimile. The present invention relates to a lens unit of an optical scanning device used in a forming apparatus.

  Image forming apparatuses such as digital copying machines, laser printers, and facsimiles have become widespread. In such an image forming apparatus, an optical scanning device that scans a light beam by a laser beam is used. When an image is formed by an image forming apparatus, the photosensitive member is charged by a charging device, and then writing is performed according to image information by an optical scanning device to form an electrostatic latent image on the photosensitive member. Then, the electrostatic latent image on the photoreceptor is visualized with toner supplied from the developing device. The toner image visualized on the photosensitive member is transferred onto a recording sheet by a transfer device, and further fixed on the recording sheet by a fixing device, whereby a desired image can be obtained.

  In color image forming apparatuses such as digital copying machines and laser printers, a tandem system in which a plurality of photoconductors are arranged in tandem has been put into practical use as the speed thereof increases. Here, for example, four photosensitive drums are arranged in the conveyance direction of the recording paper, and these photosensitive members are simultaneously exposed by a scanning optical system corresponding to each of these photosensitive drums to form a latent image. The image is developed with a developing device using developers of different colors such as yellow, magenta, cyan, and black. Then, these visualized toner images are sequentially superimposed and transferred onto the same recording paper to obtain a color image.

  In the above optical scanning device, a configuration is generally adopted in which a light beam emitted from a laser diode is converted into parallel light by a collimator lens, and then the light beam is incident on a polygon mirror to be scanned. The light beams scanned by the polygon mirror are respectively imaged on the four photoconductors via the Fθ lens.

  The laser diode is attached to a lens holder, for example. The collimator lens is accommodated in the lens barrel, and an aperture for shaping parallel light emitted from the collimator lens is integrally attached to the lens barrel. The lens barrel is arranged on the front side of the lens holder to which the laser diode is attached. The lens unit of the light source unit is configured by the lens barrel and the aperture that accommodate these collimator lenses.

  In the lens unit as described above, it is necessary to adjust the distance between the laser diode and the collimator lens. As described above, the light beam emitted from the laser diode becomes parallel light by the collimator lens, and then forms an image on the photosensitive drum through a plurality of optical elements. At this time, in order to optimize the imaging state on the photosensitive drum, the lens unit including the collimator lens is moved along the optical axis so that the imaging position of the light beam is optimized on the surface of the photosensitive drum. Can be adjusted to any position.

For example, Patent Document 1 discloses a lens unit that can perform stable optical axis alignment between a semiconductor laser and a collimator lens. Here, an adjustment jig is used for moving the housing provided with the aperture in the optical axis direction of the collimator lens. The end face of the aperture is formed to be tapered in the vertical direction. Here, when the protrusion of the adjustment jig is brought into contact with the end face of the aperture, the taper shape causes the protrusion of the adjustment jig to come into contact with a relatively lower part of the end face of the aperture. When moving the lens in the optical axis direction (horizontal direction), the casing can be stably moved in the optical axis direction.
JP 2004-170854 A

  FIG. 20 is a diagram for explaining a conventional lens unit position adjusting method. FIG. 20A is a schematic side view of a lens barrel in which an adjusting member is inserted, and FIG. 20A shows an adjustment groove provided in the lens barrel. FIG. 20B is a schematic diagram of a main part viewed from above, and FIG. 20C is a diagram for explaining the rotational moment of the lens barrel at this time. In FIG. 20, 101 is a laser diode, 107 is a lens barrel including a collimator lens, 107a is an adjustment groove, 130 is an adjustment member for adjusting the position of the lens barrel, 131 is a holding member for holding the lens barrel, and x is This is the optical axis direction of the collimator lens.

  Adjustment is performed to optimize the imaging position of the light beam on the photosensitive drum by moving the lens barrel 107 containing the collimator lens in the optical axis direction x. At this time, conventionally, the operator inserts the adjustment member 130 into the adjustment groove 107a provided in the upper portion of the lens barrel 107, and moves the adjustment member 130 in the optical axis direction x. The distance was adjusted.

  As shown in FIGS. 20A and 20B, the adjustment member 130 is inserted into the adjustment groove 107a, and the adjustment member 130 is moved in the direction x1 in which the collimator lens and the laser diode 101 are separated in the optical axis direction x. When adjusting, the adjustment member 130 and the lens barrel 107 come into contact with each other at the contact point r of the front side wall portion of the adjustment groove 107a.

  At this time, the front lower end portion q of the lens barrel 107 is caught by the wall surface of the holding member 131 that holds the lens barrel 107, and the lens barrel 107 attempts to rotate with the front lower end portion q as a fulcrum. In this case, a gap is generated between the rear lower end p of the lens barrel 107 and the holding member that holds the lens barrel 107, and the lens barrel 107 is lifted. Due to such an action, there arises a problem that the movement of the lens barrel 107 in the direction x1 cannot be performed smoothly. In this case, it is difficult to accurately adjust the position of the collimator lens.

  In this case, as shown in FIG. 20C, a rotational moment Ma is generated with the front lower end q of the lens barrel 107 as a fulcrum. The rotational moment Ma at this time is Ma = F1 · La. Here, F1 is a force required to move the lens barrel 107 in the direction x1, and La is a height from the front lower end q of the lens barrel 107 to a position corresponding to the contact point r.

  The present invention has been made in view of the above circumstances, and a lens unit adjustment mechanism capable of accurately performing position adjustment between a laser diode and a collimator lens, and a high-quality image by the lens unit adjustment mechanism. It is an object of the present invention to provide an optical scanning apparatus and an image forming apparatus that can perform image formation.

In order to solve the above problems, a first technical means is provided with a lens barrel which accommodates a collimator lens, and a lens barrel receiving portion for supporting the lens barrel, can be moved in the optical axis direction of the lens barrel child Li meter lens In the lens unit adjustment mechanism configured as described above, the lens unit adjustment mechanism has an adjustment member having a circular outer periphery with a predetermined diameter, and the lens barrel is engaged with an adjustment member that engages an adjustment member that moves the lens barrel in the optical axis direction. The adjusting groove has two inclined surfaces inclined in the moving direction of the lens barrel, and the outer periphery of the adjusting member is in contact with the two inclined surfaces one by one. .

A second technical means is the first technical means, a line perpendicular to the inclined surface is adjusted member having a contact point to the contact point as and in one one of the two contact points for contact with the inclined surface, It is characterized in that it passes between two bottom corners before and after the movement direction of the lens barrel.

  According to a third technical means, in the second technical means, both of two lines passing through the respective contact points and perpendicular to the inclined surface having the respective contact points are two bottom surface angles before and after the moving direction of the lens barrel. It is characterized by passing between the parts.

  According to a fourth technical means, in any one of the first to third technical means, the lens unit adjustment mechanism includes a pressing member that presses the lens barrel, and the pressing member is a flat area in a contact area that contacts the lens barrel. It is characterized by having.

  A fifth technical means includes a lens unit adjustment mechanism in any one of the first to fourth technical means, a light source, and a polygon mirror, and applies a light beam emitted from the light source to a collimator lens to form a polygon. An optical scanning device characterized by irradiating a mirror and scanning a light beam by rotation of a polygon mirror.

  A sixth technical means includes the optical scanning device in the fifth technical means and a photosensitive member that is exposed by irradiation with a light beam scanned by the optical scanning device, and forms a latent image on the photosensitive member by the optical scanning device. The image forming apparatus is characterized in that the latent image is visualized to form an image.

  According to the present invention, it is possible to obtain a lens unit adjustment mechanism capable of accurately performing position adjustment between a laser diode and a collimator lens, thereby enabling high-quality image formation. An optical scanning device and an image forming apparatus including the optical scanning device can be provided.

That is, according to the present invention, the adjustment groove is provided in the lens barrel that accommodates the collimator lens, the adjustment groove has two inclined surfaces that are inclined in the moving direction when the lens barrel moves, and the adjustment member is The outer periphery is circular and is configured to contact each of the two inclined surfaces one by one, thereby generating a downward force by contact with the adjusting member, and lifting the barrel that houses the collimator lens. Can be suppressed.
At this time, since the adjustment member contacts at two points on the inclined surface, the line connecting the two contact points is less likely to deviate from the moving direction of the lens barrel, and it is difficult to move in a direction inclined from the moving direction. Can be moved.

  According to the invention, the line passing through one contact point of the two contact points where the adjustment member contacts the inclined surface and perpendicular to the inclined surface having the contact point is two in front and rear in the moving direction of the lens barrel. By configuring it to pass between the bottom corners, the bottom corner of the case is caught by the holding member that holds the lens barrel in the forward direction of movement when the case is moved, and the lens barrel rotates around that part as a fulcrum. Thus, it is possible to prevent the floating from occurring in the rear in the moving direction.

  Further, according to the present invention, the line passing through the contact point where the adjustment member contacts the inclined surface and perpendicular to the inclined surface having the contact point is the two bottom corners (front surface of the lens barrel) before and after the moving direction of the lens barrel. (Bottom end or rear bottom end), the bottom corner is caught on the bottom in the moving direction when the lens barrel is moved, and the lens barrel rotates and moves with the bottom corner as a fulcrum. It is possible to prevent the floating from occurring in the rear direction.

  Further, according to the present invention, of the contact points, a line passing through one contact point and perpendicular to the inclined surface having the one contact point passes between the two bottom corners before and after the moving direction of the lens barrel. By doing so, the restrictions on the design of the inclination angle of the inclined surface and the lens barrel length are reduced, and the degree of freedom in design is increased.

  Further, according to the present invention, since the pressing member that holds the lens barrel has a flat area in the contact area that contacts the lens barrel, the contact area with the lens barrel increases, and the contact portion where the adjusting member abuts is damaged. Therefore, it is possible to prevent the holding member and the lens barrel from being caught due to the occurrence of scratches, and to prevent the lens barrel containing the collimator lens from floating.

  FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus in which the optical scanning device of the present invention is used. The image forming apparatus forms multicolor and single color images on a predetermined sheet (recording paper) in accordance with image data transmitted from the outside. As shown in the figure, an exposure unit 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, an intermediate transfer belt unit 6, a fixing unit 7, a paper feed cassette 8, a paper discharge tray 9, and the like are provided. Configured.

  Note that image data handled in the image forming apparatus corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Accordingly, four developing devices 2, photosensitive drums 3, charging devices 5, and cleaner units 4 are provided to form four types of latent images corresponding to the respective colors, and are respectively provided in black, cyan, magenta, and yellow. These are set to form four image stations.

The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. As shown in FIG. 1, in addition to a contact type roller type or brush type charger, a charger type charging unit is used. A vessel may be used.

  The exposure unit 1 corresponds to an optical scanning apparatus according to the present invention, and is configured as a laser scanning unit (LSU) including a laser irradiation unit and a reflection mirror as shown in FIG. The exposure unit 1 includes a polygon mirror 201 that scans a laser beam, and optical elements such as a lens and a mirror for guiding the light beam reflected by the polygon mirror 201 to the photosensitive drum 3. The configuration of the optical scanning device constituting the exposure unit 1 will be specifically described later. In addition, the exposure unit 1 may use a technique such as an EL or LED writing head in which other light emitting elements are arranged in an array.

  The exposure unit 1 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 3 according to the input image data. The developing unit 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toner of four colors (YMCK). The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The intermediate transfer belt unit 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt tension mechanism 63, an intermediate transfer belt driven roller 64, an intermediate transfer roller 65, and An intermediate transfer belt cleaning unit 66 is provided. Four intermediate transfer rollers 65 are provided corresponding to each color for YMCK.

  The intermediate transfer belt drive roller 62, the intermediate transfer belt tension mechanism 63, the intermediate transfer belt driven roller 64, and the intermediate transfer roller 65 stretch the intermediate transfer belt 61 and rotate it in the direction of arrow M. Each intermediate transfer roller 65 is rotatably supported by an intermediate transfer roller mounting portion of the intermediate transfer belt tension mechanism 63 of the intermediate transfer belt unit 6, and the toner image on the photosensitive drum 3 is transferred onto the intermediate transfer belt 61. Provides transfer bias for transfer.

  The intermediate transfer belt 61 is provided so as to be in contact with each photoconductor drum 3, and the toner images of the respective colors formed on the photoconductor drum 3 are sequentially transferred to the intermediate transfer belt 61 and transferred. Further, it has a function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61. The intermediate transfer belt 61 is formed endlessly using a film having a thickness of about 100 μm to 150 μm.

  The transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 61 is performed by an intermediate transfer roller 65 that is in contact with the back side of the intermediate transfer belt 61. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 65 in order to transfer the toner image. The intermediate transfer roller 65 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In this embodiment, a roller shape is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic images visualized on the respective photosensitive drums 3 according to the respective hues are stacked on the intermediate transfer belt 61. As described above, the laminated image information is transferred onto the sheet by the transfer roller 10 disposed at a contact position between the sheet and the intermediate transfer belt 61 described later by the rotation of the intermediate transfer belt 61.

At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the sheet is applied to the transfer roller 10 (the polarity opposite to the toner charging polarity (−)). (+) High voltage). Further, in order to obtain the nip constantly, the transfer roller 10 uses either the transfer roller 10 or the intermediate transfer belt drive roller 62 as a hard material (metal or the like), and the other as a soft material (elasticity such as an elastic roller). A rubber roller, a foaming resin roller, or the like) is used.

  Further, as described above, the toner adhered to the intermediate transfer belt 61 by contacting the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the sheet by the transfer roller 10 is used in the next step. Therefore, the intermediate transfer belt cleaning unit 66 is configured to remove and collect the toner. The intermediate transfer belt cleaning unit 66 includes a cleaning blade as a cleaning member that contacts the intermediate transfer belt 61, for example, and the intermediate transfer belt 61 that contacts the cleaning blade is supported by an intermediate transfer belt driven roller 64 from the back side. ing.

  The paper feed cassette 8 is a tray for storing sheets (recording paper) used for image formation, and is provided below the exposure unit 1 of the image forming apparatus. A paper discharge tray 9 provided at the upper part of the image forming apparatus is a tray for collecting printed sheets face down.

  In addition, the image forming apparatus is provided with a substantially vertical sheet conveyance path S for sending the sheets of the sheet feeding cassette 8 to the sheet discharge tray 9 via the transfer roller 10 and the fixing unit 7. In the vicinity of the paper transport path S from the paper feed cassette 8 to the paper discharge tray 9, a pickup roller 11, a plurality of transport rollers 12a to 12e, a registration roller 13, a transfer roller 10, a fixing unit 7, and the like are arranged.

  The conveyance rollers 12 a to 12 e are small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 12 a to 12 e are provided along the sheet conveyance path S. The pickup roller 11 is provided near the end of the paper feed cassette 8 and picks up sheets one by one from the paper feed cassette 8 and supplies them to the paper transport path S.

  Further, the registration roller 13 temporarily holds the sheet being conveyed through the sheet conveyance path S. The sheet has a function of conveying the sheet to the transfer roller 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 and the leading edge of the sheet are aligned.

  The fixing unit 7 includes a heat roller 71 and a pressure roller 72, and the heat roller 71 and the pressure roller 72 rotate with the sheet interposed therebetween. The heat roller 71 is set by the control unit so as to reach a predetermined fixing temperature based on a signal from a temperature detector (not shown). It has the function of fusing, mixing, and pressing the transferred multicolor toner image and thermally fixing the sheet.

  Next, the sheet conveyance path will be described in detail. As described above, the image forming apparatus is provided with the paper feed cassette 8 that stores sheets in advance. In order to feed sheets from the sheet feeding cassette 8, pickup rollers 11 are arranged so as to guide the sheets one by one to the conveyance path S.

The sheet conveyed from the sheet feeding cassette 8 is conveyed to the registration roller 13 by the conveying roller 12a in the sheet conveying path S, and conveyed to the transfer roller 10 at a timing when the leading edge of the sheet and the leading edge of the image information on the intermediate transfer belt 61 are aligned. The image information is written on the sheet. Thereafter, the sheet passes through the fixing unit 7 so that the unfixed toner on the sheet is melted and fixed by heat, and then discharged onto the sheet discharge tray 9 through the conveyance roller 12c disposed.

  The above-mentioned conveyance path is for a single-sided printing request for a sheet. On the other hand, when a double-sided printing request is made, the trailing edge of the sheet that has finished single-sided printing and has passed through the fixing unit 7 as described above. When chucked by the final transport roller 12c, the transport roller 12c rotates backward to guide the sheet to the transport rollers 12d and 12e. Then, after printing is performed on the back side of the sheet through the registration roller 13, the sheet is discharged to the discharge tray 9.

Next, an embodiment of the optical scanning device of the present invention will be specifically described.
The optical scanning device of this embodiment has a plurality of photosensitive drums 3 as described above, and each photosensitive drum 3 is simultaneously scanned and exposed by a plurality of light beams, and each photosensitive drum 3 has a different color. The present invention can be applied to a tandem image forming apparatus that forms an image and forms a color image by superimposing the images of the respective colors on the same transfer medium.

As described above, the image forming apparatus includes a photosensitive drum for black (K) image formation, a photosensitive drum for cyan (C) image formation, a photosensitive drum for magenta (M) image formation, and yellow (Y ) Photosensitive drums for image formation are arranged at substantially equal intervals. The tandem image forming apparatus forms images of the respective colors at the same time, so that the time required for forming a color image can be greatly shortened.
In the following, black, cyan, magenta, and yellow are represented by K, C, M, and Y, respectively.

  The optical scanning device according to the present invention for exposing the photosensitive drum 3 includes a unitary primary optical system (incident optical system) and a secondary optical system (exit optical system). The primary optical system includes four semiconductor lasers that respectively emit YMCK light beams, and optical elements such as mirrors and lenses that guide these light beams to the polygon mirror 201 (rotating polygon mirror) of the secondary optical system. ing. The secondary optical system includes the polygon mirror 201 that scans a laser beam on a photosensitive drum 3 that is a scanning target, and a lens and mirror for guiding the light beam reflected by the polygon mirror 201 to the photosensitive drum 3. And the like, and a BD sensor for detecting a light beam. Further, the polygon mirror 201 employs a configuration shared by each color.

  FIG. 2 is a plan view showing a configuration example of a primary optical system unit of the optical scanning device of the present invention, and FIG. 3 is a schematic perspective view of the primary optical system unit of FIG. 2 and 3, 100 is a primary optical system unit, 101 is a laser diode, 102 is a collimator lens, 103 is an aperture, 104 is a laser drive substrate, 105 is a laser holder, 106 is a lens holder, 107 is a lens barrel, 108 is a mounting screw, 110 is a first mirror, 111 is a second mirror, 112 is a cylindrical lens, 113 is a third mirror, 115 is a pressing member for pressing the lens barrel, and 120 is an optical element of the primary optical system. It is a substrate.

  Each of the laser diodes 101 for K, C, M, and Y is driven by a laser drive circuit (not shown) as light source drive means. Various control signals output from the control unit of the image forming apparatus and image data supplied from the image processing unit are input to the laser driving circuit, and light emission of each laser diode 101 is controlled according to these control signals and image data. .

K, C, M, and Y collimator lenses 102 are disposed on the laser emission side of each laser diode 101, respectively. The light beam output from each laser diode 101 is substantially elliptical diffused light, and is converted into parallel light by a collimator lens 102 provided for each color. After each color collimator lens 102, an aperture (slit) 103 having a predetermined gap is arranged to regulate the diameter of the light beam. In this specification, parallel light refers to a state in which the diameter of the light beam does not change even when the beam travels, and is distinguished from a state in which the optical axes of a plurality of beams are parallel to each other.

  Each laser diode 101 is attached to a laser holder 105. The laser holder 105 is attached to the back side of the lens holder 106 that is integrally formed on the substrate of the primary optical system. A lens barrel 107 in which the collimator lens 102 and the aperture 103 are arranged is attached to the front side of the lens holder 106. The light beam emitted from the laser diode 101 is emitted to the front outside of the lens barrel 107 through the collimator lens 102 and the aperture 103. Each lens barrel 107 is pressed from above (from the side opposite to the substrate 120) by a pressing member 115.

  The light beam emitted from the lens barrel 107 of the K laser diode 101 is directed to the second mirror 111 through the K collimator lens 102 and the K aperture 103. The light beam emitted from the lens barrel 107 of the C, M, Y laser diode 101 enters the first mirror 110 through the C, M, Y collimator lens 102 and the aperture 103, respectively. The first mirror 110 includes three mirrors that individually reflect the C, M, and Y light beams, and the light beams for the respective colors reflected by these mirrors travel in the traveling direction of the K light beam. , And enters the second mirror 111.

  The laser diodes 101 of the respective colors are arranged at different heights in the sub scanning direction (direction perpendicular to the substrate surface). The difference in height is set to about 2 mm, for example. The first mirror 110 is disposed at a position where only the light beam emitted from the corresponding laser diode 101 can be reflected. Further, the three mirrors (for C, M, and Y) constituting the first mirror 110 are arranged at positions overlapping the light beam emitted from the K laser diode 101 when viewed from the main scanning direction.

  With the configuration as described above, the K light beam emitted from the K laser diode 101 and the C, M, and Y light beams reflected by the first mirror 110 all coincide in the main scanning direction, There is a deviation (level difference) in the sub-scanning direction, and the optical axes of the respective light beams are incident on the second mirror 111 in parallel with each other. Here, the light beam for each color emitted from each collimator lens 102 is parallel light whose diameter does not change even when the light beam travels.

  The second mirror 111 causes the incident light beams for K, C, M, and Y colors to enter the cylindrical lens 112. The cylindrical lens 112 is arranged to focus the incident light beam for each color in the sub-scanning direction. Then, the light beam for each color emitted from the cylindrical lens 112 is reflected by the third mirror 113 and enters the reflecting surface of the polygon mirror 201.

  Here, the cylindrical lens 112 has a lens power in the sub-scanning direction, and the light beam converges near the reflecting surface of the polygon mirror 201 in the sub-scanning direction according to the optical path length from the cylindrical lens 112 to the polygon mirror 201. It is set to be. That is, the light beams for the respective colors incident on the cylindrical lens 112 as parallel lights are almost converged on the reflection surface of the polygon mirror 201 in the sub-scanning direction. At the same time, the light beams for the respective colors incident on the cylindrical lens 112 with their optical axes parallel to each other converge at substantially the same position on the surface of the polygon mirror 201 in the sub-scanning direction.

Since this cylindrical lens 112 does not have lens power in the main scanning direction, the incident light beam for each color is emitted as parallel light as it is in the main scanning direction and is incident on the reflecting surface of the polygon mirror 201. To do. Usually, parallel light is incident on the polygon mirror 201 in the main scanning direction. Converging light in the main scanning direction is not preferable because a negative field curvature is generated by an fθ lens described later. Further, the sub-scanning direction is converged on the surface of the reflecting surface in order to correct the surface tilt of the reflecting surface. For example, the position of the light beam incident on the reflection surface of the polygon mirror 201 in the sub-scanning direction is near the center in the height direction of the reflection surface.

  In the optical scanning device of this embodiment, four light beams for YMCK are deflected by one polygon mirror 201 of the secondary optical system. In this case, it is necessary to be able to separate the four light beams after passing through the polygon mirror 201 and to prevent the light beams for each color from shifting in the main scanning direction. For this reason, the four light beams emitted from the cylindrical lens 112 of the primary optical system are incident on the polygon mirror 201 from the same direction in the main scanning direction to the same position, and the angular difference in the sub-scanning direction. It is set so as to be incident at substantially the same position from a certain direction. These optical path settings are made by arranging the laser diodes 101 having a difference in height in the sub-scanning direction, so that the light beams for the respective colors all match in the main scanning direction and have a predetermined height difference in the sub-scanning direction. It is realized by progressing. Thereby, the light beam for each color can be separated by the scanning optical system.

  Also, with the above configuration, since the light beams for each color are parallel light and their optical axes are parallel to each other on the optical path from the collimator lens 102 for each color of the primary optical system to the cylindrical lens 112, the collimator lens 102. To the cylindrical lens 112 can be freely set.

  FIG. 4 is a diagram showing a configuration example of the secondary optical system of the optical scanning device. FIG. 4A is a configuration diagram of the interior of the housing of the secondary optical system unit as viewed from above, and the interior of the housing 223 as viewed from the side. FIG. 4B shows a schematic configuration of the photosensitive member. 4, 200 is a secondary optical system unit, 201 is a polygon mirror, 202 is a first fθ lens, 203 is a second fθ lens, 204 is a K mirror, 205 is a first mirror for C, and 206 is a second mirror for C. , 207 is a third mirror for C, 208 is a first mirror for M, 209 is a second mirror for M, 210 is a first mirror for Y, 211 is a second mirror for Y, 212 is a third mirror for Y, 213 Is a synchronous mirror, 214 is a BD sensor lens, 215 is a BD sensor, 220 is a cylindrical lens for each color, 221a and 221b are fixing shafts, 222 is an installation position of the primary optical system unit, 223 is a housing, and 224 is a cylindrical A frame that holds the lens.

  The polygon mirror 201 has a plurality of (for example, seven) reflecting surfaces in the rotation direction, and is driven to rotate by a polygon motor (not shown). The polygon motor is installed in a recess on the back side of the casing 223 where the polygon mirror 201 is installed, and a lid for sealing the recess is provided. The polygon motor is provided with fins for heat dissipation. The light beams of the respective colors emitted from the laser diode 101 of the primary optical system and reflected by the third mirror 113 are reflected by the reflecting surface of the polygon mirror 201 of the secondary optical system, and then the photosensitive member through the respective optical elements. The drum 3 is scanned.

As described above, each laser beam incident on the polygon mirror 201 with an angle difference in the sub-scanning direction maintains the angle difference and passes through the scanning optical system including the first fθ lens 202 and the second fθ lens 203. It will be separated later.
The first fθ lens 202 has lens power in the main scanning direction. Thereby, in the main scanning direction, the light beam of the parallel light emitted from the polygon mirror 201 is converged so as to have a predetermined beam diameter on the surface of the photosensitive drum 3. The first fθ lens 202 has a function of converting a light beam that moves at a constant angular velocity in the main scanning direction by a constant angular velocity movement of the polygon mirror 201 so as to move on the scanning line on the photosensitive drum 3 at a constant linear velocity. Have.

  The second fθ lens 203 has a lens power mainly in the sub-scanning direction. As a result, the diffused light beam emitted from the polygon mirror 201 is converted into parallel light in the sub-scanning direction. The second fθ lens 203 also has lens power in the main scanning direction, and complements the functions of the first fθ lens 202 so that the beam diameter can be controlled and the beam linear velocity movement can be executed with high accuracy.

  The first fθ lens 202 and the second fθ lens 203 are made of resin. In order to form an aspherical shape for obtaining desired characteristics of the fθ lens, it is preferable to use a resin material for the fθ lens. In particular, since the second fθ lens 203 has lens power in both the main scanning direction and the sub-scanning direction, in order to obtain a complicated aspherical shape that realizes this, it can be manufactured using a resin material. preferable. As the resin material, an optimum material is selected in consideration of characteristics such as transparency, moldability, photoelastic modulus, heat resistance, hygroscopicity, mechanical strength, and cost.

Of the four light beams for each color separated by the polygon mirror 201 and passed through the first and second fθ lenses 202 and 203, the K light beam passes through the first and second fθ lenses 202 and 203. The light is reflected by the K mirror 204, passes through the K cylindrical lens 220, and enters the photosensitive drum 3 (K). Drawing is performed in the scanning area on the photosensitive drum 3.
The separated Y light beam is reflected by the Y first to third mirrors 210, 211, and 212, passes through the Y cylindrical lens 220, and enters the photosensitive drum 3 (Y). Similarly, the separated C light beam is reflected by the C first to third mirrors 205, 206, and 207, passes through the C cylindrical lens 220, and enters the photosensitive drum 3 (C). The separated light beam for M is reflected by the first and second mirrors 208 and 209 for M and enters the photosensitive drum 3 (M) through the cylindrical lens 220 for M.

  In the secondary optical system, the cylindrical lens 220 for each color has lens power in the sub-scanning direction. Thereby, in the sub-scanning direction, the light beam incident as parallel light is converged on the photosensitive drum 3 so as to have a predetermined beam diameter. In the main scanning direction, the light beam that has been converged by the first fθ lens 202 is converged on the photosensitive drum 3 as it is. The cylindrical lens 220 is formed using a resin. The long cylindrical lens 220 that covers the entire scanning width as in the optical scanning device is preferably a resin lens.

  The light beams of the respective colors emitted from the cylindrical lens 220 expose the charged photosensitive drum 3 according to the image data. As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 3. Then, the electrostatic latent images formed on the respective photosensitive drums 3 are visualized by YMCK toner by the developing unit.

  The state of the light beam of each color between the optical elements in the above-described embodiment will be described below. FIG. 5 is a diagram for explaining the state of each light beam of each color of the primary optical system and the secondary optical system, and FIG. 5A schematically shows the shape of one light beam in the main scanning direction. FIG. 5B is a diagram schematically showing the shape of one light beam in the sub-scanning direction.

First, the behavior of the light beam in the main scanning direction shown in FIG. The light beam emitted from the laser diode 101 of the primary optical system enters the collimator lens 102 as diffused light. With respect to the main scanning direction at this time, the angle of the diffused light from the laser diode 101 is about 30 °.
The collimator lens 102 converts the incident diffused light into parallel light and emits it. An aperture 103 is provided after the collimator lens 102, and the diameter of the light beam is regulated by the opening of the aperture 103. Here, the aperture diameter of the aperture 103 in the main scanning direction is about 7 mm.

The parallel light beam emitted from the aperture 103 passes through the first mirror 110 and the second mirror 111 (only the second mirror 111 for K) (not shown in FIG. 5) to the cylindrical lens 112 of the primary optical system. Incident. Since the cylindrical lens 112 of the primary optical system does not have lens power in the main scanning direction, the incident parallel light passes here as it is.
The parallel light beam emitted from the cylindrical lens 112 is incident on the reflection surface of the polygon mirror 201 via the third mirror 113 (not shown in FIG. 5). As shown in the figure, the angle of the reflecting surface of the polygon mirror 201 changes in the main scanning direction with the rotation.

The parallel light beam reflected by the polygon mirror 201 enters the first fθ lens 202 while moving in the main scanning direction at a constant angular velocity, and further enters the second fθ lens 203. The first fθ lens 202 and the second fθ lens 203 have lens power in the main scanning direction, and convert a light beam incident as parallel light into convergent light that converges on the surface of the photosensitive drum 3. The light beam moving in the main scanning direction at a constant angular velocity is converted so as to move at a constant linear velocity on the scanning line on the surface of the photosensitive drum 3.
The second fθ lens 203 complements the first fθ lens 202, and further corrects the light beam emitted from the first fθ lens 202 so that the light beam exhibits a desired behavior.

  Further, on the optical path between the second fθ lens 203 and the photosensitive drum 3, mirrors (one or a plurality of mirrors for each color) for folding the optical path of each color and guiding it to the target photosensitive drum 3 (FIG. 5). ) And a cylindrical lens 220 of a secondary optical system. Since the cylindrical lens 220 has no lens power in the main scanning direction, the light beam emitted from the second fθ lens 203 is directed to the photosensitive drum 3 without being affected in the main scanning direction. At this time, the spot diameter of the light beam on the photosensitive drum 3 in the main scanning direction is about 60 μm.

Next, the behavior of the light beam in the sub-scanning direction shown in FIG. The light beam emitted from the laser diode 101 becomes diffused light and enters the collimator lens 102 as in the main scanning direction. However, with respect to the sub-scanning direction at this time, the angle of the diffused light from the laser diode 101 is smaller than the main scanning direction and is about 11 °.
The collimator lens 102 converts the incident diffused light into parallel light and emits it. An aperture 103 is provided after the collimator lens 102, and the diameter of the light beam is regulated by the opening. Here, the aperture diameter of the aperture 103 is about 2 mm.

  The parallel light beam emitted from the aperture 103 passes through the first mirror 110 and the second mirror 111 (only the second mirror 111 for K) (not shown in FIG. 5) to the cylindrical lens 112 of the primary optical system. Incident. The cylindrical lens 112 of the primary optical system has a lens power in the sub-scanning direction, and incident parallel light is converted into convergent light that is substantially converged by the reflecting surface of the polygon mirror 201. Here, the parallel light beam emitted from the cylindrical lens 112 is incident on the reflecting surface of the polygon mirror 201 via the third mirror 113 (not shown in FIG. 5). In the sub-scanning direction, the light beam is converged to approximately the center in the height direction of the reflecting surface. At this time, by generating a conjugate relationship between the reflection surface of the polygon mirror 201 and the surface of the photosensitive drum 3, the surface tilt of the reflection surface is corrected.

The light beam reflected by the polygon mirror 201 becomes diffused light and enters the first fθ lens 202 and further enters the second fθ lens 203. Since the first fθ lens 202 does not have lens power in the sub-scanning direction, the diffused light beam incident on the first fθ lens 202 passes as it is.
The second fθ lens 203 has a lens power in the sub-scanning direction, and converts the light beam incident as diffuse light so as to become parallel light in the sub-scanning direction.

  On the optical path between the second fθ lens 203 and the photosensitive drum 3, mirrors (one or a plurality of mirrors for each color) for folding the optical path of each color and guiding it to the target photosensitive drum 3 (FIG. (Not shown) and a cylindrical lens 220 of a secondary optical system. The cylindrical lens 220 has a lens power in the sub-scanning direction, and the parallel light beam emitted from the second fθ lens 203 is converted into light that is substantially converged on the surface of the photosensitive drum 3. At this time, the spot diameter of the light beam on the photosensitive drum 3 in the sub-scanning direction is about 67 μm.

  FIG. 6 is a diagram schematically showing optical paths of four light beams in the sub-scanning direction. When considering the optical paths of the four color light beams of YMCK, as described above, these four light beams pass through the same position in the main scanning direction, but in the sub scanning direction, the height of the laser diode 101 is the same. The laser diodes 101 are separated from each other by the difference.

  As shown in FIG. 6, the four light beams emitted from the four laser diodes 101 (for YMCK) and passed through the collimator lens 102 have their optical axes parallel to each other and are applied to the cylindrical lens 112 of the primary optical system. Incident. In the cylindrical lens 112, each of the four light beams is converted so as to converge to approximately the center on the reflection surface of the polygon mirror 201. That is, in the sub-scanning direction, the four light beams converge at substantially the same position with an angle difference with respect to the reflection surface of the polygon mirror 201. In the main scanning direction, four beams are incident on the reflecting surface of the polygon mirror 201 from the same direction at the same position. In FIG. 6, the first mirror 110 to the third mirror 113 are not shown.

  The four light beams reflected by the polygon mirror 201 are diffused again with an angular difference and enter the second fθ lens 203 from the first fθ lens 202. Since the first fθ lens 202 has no lens power in the sub-scanning direction, the four light beams incident on the first fθ lens 202 pass as they are. The second fθ lens 203 has a lens power in the sub-scanning direction, and converts the four incident light beams so that their optical axes are parallel to each other.

  On the optical path between the second fθ lens 203 and the photosensitive drum 3, a mirror (one or a plurality of mirrors for each color) for folding the optical path of each color and guiding it to the target photosensitive drum 3 (in FIG. 6, (Not shown), but these mirrors use the deviation of the optical axes of the four light beams emitted from the second fθ lens 203 to divide the four beams onto the target photosensitive drum 3 respectively. Leading to. The optical path lengths from the second fθ lens 203 of the secondary optical system to the cylindrical lens 220 are all the same in the four light beams for each color.

Next, an installation example of a BD (Beam Detect) sensor for detecting a light beam and generating a reference signal for writing before the main scanning of the light beam on the photosensitive drum 3 will be described.
Of the light beams reflected by the polygon mirror 201 and traveling toward the photosensitive drum 3, a light beam used for image formation on the photosensitive drum 3, that is, a light beam for scanning the main scanning line is referred to as a main scanning beam. To do. Here, a spatial region that passes when the main scanning beam scans is an image region, and a region other than the image region is a non-image region.

When the light beam scans the photosensitive drum 3, the light beam periodically scans the main scanning line. At this time, since the photoconductive drum 3 is rotating, the photoconductive drum 3 is scanned at a different place every predetermined period. Each time the light beam is scanned, the writing start position of the scanning line needs to be the same.
In order to detect the writing start position of the scanning line, the optical scanning device is provided with a synchronization detecting device. Referring to FIG. 4, the synchronization detection device includes a BD sensor (synchronization detection sensor) 215 for detecting the light beam in the non-image region as a synchronization detection beam, and guide means for guiding the synchronization detection beam to the BD sensor 215. The synchronous detection beam folding mirror (synchronous mirror) 213 and a BD sensor lens 214 for condensing the synchronous detection beam on the BD sensor 215 are configured.

  The synchronization detection beam is a signal for synchronization, and is a light beam reflected by the synchronization mirror 213 after the light beam emitted from the polygon mirror 201 has passed through the first and second fθ lenses 202 and 203. . The synchronous detection beam is folded back by the synchronous mirror 213 and reaches the BD sensor 215 via the BD sensor lens 214. The BD sensor 215 outputs a sensor signal corresponding to the amount of received light. Then, a control unit (for example, an LSU controller described later) of the optical scanning device generates a synchronization signal (BD signal) for determining an image writing start position based on a sensor signal from the BD sensor 215. Specifically, the BD signal is generated when the amount of light received by the BD sensor 215 is at least greater than the amount of light necessary for the laser beam to expose the photosensitive drum 3 to form an electrostatic latent image. The BD signal is used as a scanning start reference signal in the main scanning direction, and the writing start position of each line in the main scanning direction is synchronized based on this signal.

  In addition, the synchronization detection device outputs an error signal when the BD sensor 215 cannot detect the light beam. In an image forming apparatus incorporating an optical scanning device, the operation of the device is stopped, and a predetermined service code is displayed on the display screen, for example, so that the user is informed of a defect in the writing start position in the scanning direction.

  The BD sensor 215 for detecting the writing position in the main scanning direction is provided only on the optical path of the K light beam, corresponds to only the K light beam of the four light beams, and is used for other colors. By making the light beam refer to this, scanning is started at a predetermined writing start timing of image data.

FIG. 7 is a block diagram illustrating a configuration example of a control system of the optical scanning device.
The LSU controller 301 receives an image data signal output from an image memory or the like of the image processing unit 402 of the image forming apparatus, and a laser driver circuit in accordance with the scanning start timing sent from the main body control unit 401 of the image forming apparatus. (LD Driver) 302,
Lighting control of the laser diode (LD) 101 is performed.
The LSU controller 301 controls the reference rotation operation of the polygon motor 303 that makes full use of the polygon mirror so as to meet the specifications in the main scanning direction of the image forming apparatus. Further, the BD sensor 215 that detects the writing start position in the main scanning direction detects the main scanning timing by receiving the light beam, and outputs an error signal to the main body control unit 401 if there is an error. Also, a detection signal of the BD sensor 215 that detects the writing position in the sub-scanning direction is input, and if there is an error, an error signal is output to the main body control unit 401. The LSU controller 301 is configured by an ASIC (Application Specific Integrated Circuit).

  In the optical scanning apparatus as described above, in order to accurately adjust the distance between the laser diode 101 and the collimator lens 102 as described above, an inclined surface is formed in the adjustment groove of the collimator lens 102, so that the adjustment member can Even when a force is applied to the collimator lens 102 in the lateral direction (the optical axis direction of the collimator lens), the collimator lens 102 can be moved smoothly. The configuration will be specifically described below.

  FIG. 8 is a perspective view showing the configuration of the substrate before each optical element such as a collimator lens is installed. As described above, the substrate 120 is provided with the four lens holders 106 for K, C, Y, and M. A laser holder 105 having a laser diode 101 is attached to the back side of the lens holder 106, and a lens barrel 107 to which a collimator lens 102 and an aperture 103 are attached is installed on the front side of the lens holder 106. The

  A lens barrel receiving portion 114 for installing the lens barrel 107 is provided on the front side of each lens holder 106. As shown in FIG. 8, each of the lens barrel receiving portions 114 is constituted by two inclined surfaces, and the lens barrel 107 installed thereon can slide in front and rear thereof (in the optical axis direction of the collimator lens 102). ing.

  FIG. 9 is a perspective view illustrating a configuration example of a lens barrel that houses a collimator lens. In the drawing, reference numeral 107 a denotes an adjustment groove provided in the lens barrel 107. An adjustment groove 107a for adjusting the position of the collimator lens is provided at a position on the upper side (the side opposite to the substrate 120) when the lens barrel 107 is arranged in the lens barrel receiving portion 114. By inserting and engaging an adjusting member, which will be described later, into the adjusting groove 107a, the position of the lens barrel 107 (that is, the collimator lens 102) in the optical axis direction can be adjusted.

FIG. 10 is a perspective view showing a state when the adjustment member is inserted into the lens barrel of the collimator lens, and FIG. 11 is a cross-sectional view taken along the line AA in FIG. 12 is a cross-sectional view taken along the line BB in FIG. In each figure, 115 is a pressing member and 130 is an adjusting member.
When adjusting the position of the collimator lens 102 in the optical axis direction, an adjustment member 130 as shown in FIGS. 10 to 12 is inserted into an adjustment groove 107 a provided in the lens barrel 107. Then, the operator uses the adjustment member 130 to adjust the lens barrel 107 by moving it in the optical axis direction, and optimizes the light beam imaging position on the photosensitive drum 3.

  FIG. 13 is a diagram for explaining a configuration example of the lens unit of the present invention. FIG. 13 (A) is a diagram schematically showing the side surface of the lens barrel in which the adjustment member is inserted, and the adjustment groove is shown from above. FIG. 13B shows the view. In FIG. 13, x is the optical axis direction of the collimator lens.

  As described above, when adjustment is performed to optimize the imaging position of the light beam on the photosensitive drum 3 by moving the collimator lens 102 in the optical axis direction x, the upper portion of the lens barrel 107 that houses the collimator lens 102 is used. The operator can adjust the distance between the collimator lens 102 and the laser diode 101 by inserting the adjustment member 130 into the adjustment groove 107a provided in the lens and moving the adjustment member 130 in the optical axis direction x.

  Here, in this embodiment, as shown in FIG. 13, the adjustment groove 107 a provided in the lens barrel 107 is formed by two inclined surfaces t inclined in a V shape, and is adjusted to each of these inclined surfaces t. The tip of the member 130 is configured to contact. The two V-shaped inclined surfaces t are provided so as to form inclined surfaces on the front side (aperture 103 side) and rear side (laser diode 101 side) of the collimator lens 102 in the optical axis direction. That is, the two inclined surfaces t are configured as surfaces that are inclined in the moving direction when the lens barrel 107 moves.

  When the adjustment member 130 is inserted into the adjustment groove 107a with the above-described configuration and the adjustment member 130 is moved in the optical axis direction x of the collimator lens 102, at the contact points r of the two inclined surfaces t of the adjustment groove 107a, The adjustment member 130 contacts. Here, by using the adjustment member 130 having a circular cross section, the adjustment member 130 comes into contact with the inclined surface at two points.

  At this time, since the adjustment groove 107a with which the adjustment member 130 abuts is constituted by a V-shaped slope t, the lens barrel 107 is pressed downward at the contact point r on the slope t, and the slope t A vertical drag w is generated.

  FIG. 14 is a diagram for explaining the rotational moment of the lens barrel. In this case, the rotational moment Mb having the front lower end q of the lens barrel 107 as a fulcrum is sufficiently smaller than the conventional configuration due to the vertical drag w due to the inclined surface t of the adjustment groove 107a, and the lens barrel 107 is moved in the direction x. The movement can be performed smoothly.

At this time, the rotational moment Mb with the front lower end q of the lens barrel 107 as a fulcrum is Mb = F2 · Lb. Here, F2 is a force required to move the lens barrel 107 in the direction x1, and Lb is a point s where the vertical drag w passing through the contact point r intersects the front end surface of the lens barrel 107, and the lens barrel 107. It is a distance with the front side lower end part q.
Further, F2 = F4 + μF3. Here, F3 is a force applied vertically downward by the lens barrel 107, and μ is a coefficient of friction between the lens barrel 107 and the lens barrel receiving portion 114. F4 is a force required to move the lens barrel 107 in the direction x when there is no frictional force μF3. Actually, since the friction coefficient μ is very small, the rotational moment Mb can be kept low.

  As described above, the rotational moment Mb is generated in the present embodiment, but the rotational moment of the present embodiment is larger than the rotational moment Ma described in the conventional example due to the vertical drag w generated on the inclined surface t of the adjustment groove 107a. Mb can be significantly reduced, and the lens barrel 107 can be moved smoothly when the position of the lens barrel 107 is adjusted using the adjustment member 130.

  In addition, since the adjustment member 130 having a circular cross section makes point contact at the contact points r of the two inclined surfaces t of the adjustment groove, the vertical displacement of the contact point r is small, and the lens barrel 107 is moved. In addition, the effect of suppressing the tilt of the lens barrel 107 is also obtained.

  FIG. 15 is a view for explaining another configuration example of the lens unit of the present invention, and schematically shows a side surface of a lens barrel into which an adjustment member is inserted. In this configuration example, by optimizing the direction of the normal force of the inclined surface t, a rotational moment with the lower end q on the front surface of the lens barrel 107 as a fulcrum is prevented from occurring.

  Here, the inclination angle of the adjustment groove 107a (angle formed by the horizontal plane and the inclined surface t when the lens barrel is placed horizontally) θ is reduced, and the inclined surface t passing through the contact point r of the inclined surface t is reduced. The vertical drag w passes through the inner side of the front lower end q of the lens barrel 107 (the collimator lens side behind the lower front end q). In this case, with respect to the line l in the optical axis direction at the lower end of the lens barrel, the height from the line l to the contact point r is V, and from the point m where the perpendicular of the line l passing through the contact point r intersects the line l, When the length to the point n where the normal force w passing through the contact point r intersects the line l is H, H = V tan θ. At this time, the length H may be shorter than the length from the point m to the front lower end q.

  In other words, the lens barrel 107 passes through one contact point r of the two contact points r with which the adjustment member 130 having a circular cross section with a predetermined diameter contacts the inclined surface t, and the contact point r. A line perpendicular to the inclined surface t having r is configured to pass between two bottom corners (front lower end q and rear lower end p) of the lens barrel 107 before and after the moving direction.

  The above-described configuration is designed in consideration of moving the lens barrel 107 in the direction x1, but when considering moving in the direction opposite to the direction x1 (that is, on the laser diode 101 side) The relationship between the rear inclined surface t of the groove 107a and the rear lower end portion p of the lens barrel 107 may be designed based on the same idea as described above.

  Further, when it is assumed that the lens barrel 107 is moved back and forth in the direction x, both the relationship between the respective inclined surfaces t and the front lower end q and the rear lower end p are designed based on the above concept. Good. The configuration at this time is such that two lines that pass through the respective contact points r and are perpendicular to the inclined surface t having the respective contact points r are two bottom corners (front end lower end of the front and rear) of the lens barrel 107 in the moving direction. It passes between the part q and the rear lower end part p).

  FIG. 16 is a diagram for explaining still another configuration example of the lens barrel in the lens unit of the present invention. As shown in FIG. 15, the vertical drag w of the inclined surface t passing through the contact point r of the inclined surface t passes through the inner side of the front lower end q of the lens barrel 107 (the collimator lens side behind the lower front end q). With this configuration, it is possible to suppress the generation of a rotational moment with the front lower end q as a fulcrum. At this time, if the condition as shown in FIG. 15 cannot be satisfied due to the restriction of the length of the lens barrel 107 or the inclination angle θ that the inclined surface t can take, the adjustment direction of the lens barrel 107 is one direction (here 16, assuming that only the x1 direction) is provided, the installation position of the adjustment groove 107a is configured to be moved backward (laser diode 101 side) as shown in FIG.

That is, in the embodiment shown in FIGS. 13 to 15, the position where the adjustment groove 107a is provided is substantially the center in the optical axis direction of the lens barrel 107, but it is obvious that the position is not limited to this position. In the embodiment of FIG. 16, the adjustment groove 107 a is provided from the rear of the lens barrel 107. As a result, the length of the front side (aperture side) of the adjustment groove 107a in the lens barrel 107 is increased, and a configuration in which the above-described rotational moment is not generated can be easily realized. In this case, as described above, it is assumed that the position adjustment is performed by moving the lens barrel 107 in one direction x1.
If the moving direction of the lens barrel x1 is limited to the direction opposite to the above x1, the position where the adjustment groove 107a is provided may be moved to the front side (aperture side) of the lens barrel 107.

  Next, a configuration example for fixing the lens barrel 107 whose position has been adjusted to the lens barrel receiving portion 114 on the substrate 120 will be described. FIG. 17 is a view for explaining the step portion for filling the adhesive provided in the lens barrel. FIG. 17A shows a top view of the lens barrel, and FIG. 17B shows a side view of the lens barrel. It is. As shown in FIG. 17, a step portion D <b> 1 and a step portion D <b> 2 are provided around the lens barrel 107. The step portion D 1 is provided over the entire circumference of the lens barrel 107, and the step portion D 2 is provided on both sides around the lens barrel 107.

  The lens barrel 107 whose position adjustment has been completed is fixed to the lens barrel receiving portion 114 using an adhesive. In the present embodiment, a step portion D1 is provided in the lens barrel in order to stably and accurately perform the fixing with the adhesive. By filling the stepped portion D1 with an adhesive, the lens barrel 107 can be fixed to the lens barrel receiving portion 114 stably and with high accuracy. At this time, the step d1 between the stepped portion D1 and the outermost peripheral portion of the lens barrel 107 is, for example, about 0.1 mm or less. Further, the step portion D2 can secure a working space when the step portion D1 is filled with the adhesive.

FIG. 18 is a schematic view of a main part for explaining a state in which the lens barrel is fixed to the lens barrel receiving portion. In the figure, reference numeral 140 denotes an adhesive.
The lens barrel 107 configured as shown in FIG. 17 is aligned on the lens barrel receiving portion 114 and fixed to the lens barrel receiving portion 114 using an adhesive 140. The adhesive 140 is filled in the region of the step portion D1 having the step d1 and flows and solidifies also below the lens barrel receiving portion 114, so that the lens barrel 107 can be fixed in a well-balanced manner. Reliability can be ensured.

Next, a configuration example of the pressing member 115 that holds the lens barrel 107 from above will be described.
FIG. 19 is an enlarged cross-sectional view of a main part around the lens barrel 107 installed at a fixed position. As described above, the lens barrel 107 is pressed from above (from the side opposite to the substrate 120) by the pressing member 115. At this time, the pressing member 115 and the lens barrel 107 are in line contact with each other through the contact region 115a. (Normally, since the lens barrel contact portion of the presser member is R-shaped, it is point-contacted with the cylindrical lens barrel.) That is, the presser member 115 has a flat region 115 a in the contact region that contacts the lens barrel 107. Yes. With such a configuration, the lens barrel 107 can be stably maintained.

  In particular, when the position of the lens barrel 107 is adjusted in the optical axis direction of the collimator lens, the pressing member 115 is scratched on the abutting portion of the lens barrel 107 that abuts the lens barrel 107, and this scratch causes the pressing member and the mirror to be in contact with each other. The tube is caught and the lens barrel 107 is prevented from floating from the lens barrel receiving portion 114, and stable adjustment can be performed during the position adjustment.

1 is a diagram illustrating a configuration example of an image forming apparatus in which an optical scanning device of the present invention is used. It is a top view which shows the structural example of the primary optical system unit of the optical scanning apparatus of this invention. FIG. 3 is a schematic perspective view of the primary optical system unit in FIG. 2. It is a figure which shows the structural example of the secondary optical system of an optical scanning device. It is a figure for demonstrating the state of each light beam of each color of a primary optical system and a secondary optical system. It is a figure which shows typically the optical path of four light beams in a subscanning direction. It is a block diagram explaining the structural example of the control system of an optical scanning device. It is a perspective view which shows the structure of the board | substrate before installing each optical element, such as a collimator lens. It is a perspective view which shows the structural example of the lens-barrel which accommodated the collimator lens. It is a perspective view which shows a state when an adjustment member is inserted in the lens barrel of a collimator lens. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a figure for demonstrating the structural example of the lens unit of this invention. It is a figure for demonstrating the rotational moment of a lens-barrel. It is a figure for demonstrating the other structural example of the lens unit of this invention. It is a figure for demonstrating the further another structural example of the lens-barrel in the lens unit of this invention. It is a figure for demonstrating the level | step-difference part for adhesive filling provided in the lens-barrel. It is a principal part schematic diagram for demonstrating the state which fixed the lens-barrel to the lens-barrel receiving part. It is a principal part expanded sectional view around the lens-barrel installed in the fixed position. It is a figure for demonstrating the position adjustment method of the conventional lens unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Exposure unit, 2 ... Developing device, 3 ... Photosensitive drum, 4 ... Cleaner unit, 5 ... Charger, 6 ... Intermediate transfer belt unit, 7 ... Fixing unit, 8 ... Paper feed cassette, 9 ... Paper discharge tray, DESCRIPTION OF SYMBOLS 10 ... Transfer roller, 11 ... Pick-up roller, 12a, 12b, 12c, 12d, 12e ... Conveyance roller, 13 ... Registration roller, 61 ... Intermediate transfer belt, 62 ... Intermediate transfer belt drive roller, 63 ... Intermediate transfer belt tension mechanism, 64 ... Intermediate transfer belt driven roller, 65 ... Intermediate transfer roller, 66 ... Intermediate transfer belt cleaning unit, 71 ... Heat roller, 72 ... Pressure roller, 100 ... Primary optical system unit, 101 ... Laser diode, 102 ... Collimator lens , 103 ... Aperture, 104 ... Laser drive substrate, 105 ... Laser holder, 106 ... Len Holder 107... Lens barrel 107 a. Adjustment groove 108. Mounting screw 110. First mirror 111. Second mirror 112. Cylindrical lens 113. Third mirror 114. Pressing member, 115a ... contact region, 120 ... substrate, 130 ... adjusting member, 131 ... holding member, 140 ... adhesive, 200 ... secondary optical system unit, 201 ... polygon mirror, 202, 203 ... f [theta] lens, 204-212 Mirror, 213 ... Synchronous mirror, 214 ... BD sensor lens, 215 ... BD sensor, 220 ... Cylindrical lens, 221a, 221b ... Shaft for fixing, 223 ... Housing, 301 ... LSU controller, 303 ... Polygon motor, 401 ... Body Control unit, 402... Image processing unit.

Claims (6)

In a lens unit adjustment mechanism that includes a lens barrel that stores a collimator lens, and a lens barrel receiving portion that supports the lens barrel, and the lens barrel is configured to be movable in the optical axis direction of the collimator lens.
The lens unit adjustment mechanism has an adjustment member having a circular outer periphery of a predetermined diameter,
The barrel has an adjustment groove the adjusting member for moving the lens barrel in the optical axis direction is engaged, the adjustment groove has two inclined surfaces inclined in the moving direction of the lens barrel The lens unit adjusting mechanism , wherein the outer periphery of the adjusting member is in contact with the two inclined surfaces one by one. The lens unit adjustment mechanism according to claim 1, wherein a line perpendicular to the inclined surface passing through one of the two contact points where the adjustment member contacts the inclined surface and having the one contact point is provided. A lens unit adjusting mechanism that passes between two corners of the bottom surface of the lens barrel in the moving direction.   3. The lens unit adjusting mechanism according to claim 2, wherein two lines passing through the respective contact points and perpendicular to the inclined surface having the respective contact points are two bottom surfaces before and after the moving direction of the lens barrel. A lens unit adjusting mechanism that passes between corners.   4. The lens unit adjustment mechanism according to claim 1, wherein the lens unit adjustment mechanism includes a pressing member that presses the lens barrel, and the pressing member is flat in a contact region that contacts the lens barrel. 5. A lens unit adjustment mechanism having a region.   A lens unit adjustment mechanism according to any one of claims 1 to 4, a light source, and a polygon mirror, wherein the polygon mirror is irradiated with a light beam emitted from the light source on the collimator lens, An optical scanning device characterized in that a light beam is scanned by rotation of the polygon mirror.   An optical scanning device according to claim 5 and a photosensitive member that is exposed by irradiating a light beam scanned by the optical scanning device, forms a latent image on the photosensitive member by the optical scanning device, and An image forming apparatus that forms an image by visualizing an image.

Images