JP6274512B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning device and an image forming apparatus, and more particularly to an optical scanning device that scans a surface to be scanned with light, and an image forming apparatus including the optical scanning device.

  In electrophotographic image recording, an image forming apparatus using a laser is widely used. Generally, this image forming apparatus includes an optical scanning device for scanning the surface of a photosensitive drum with a laser beam and forming a latent image on the surface of the drum.

  The optical scanning device includes a light source, a pre-deflector optical system, an optical deflector, and a scanning optical system. The laser light emitted from the light source enters the optical deflector via the pre-deflector optical system, is reflected by the rotary polygon mirror of the optical deflector, and is then guided to the drum via the scanning optical system.

  For example, Patent Document 1 discloses a deflector mounting structure in which different types of deflectors are mounted on a common housing via a connection plate, and a scanning optical device including the mounting structure.

  However, in the scanning optical device disclosed in Patent Document 1, the imaging performance of the scanning optical system may be deteriorated.

The present invention is an optical scanning device that scans a surface to be scanned with light, and includes a light source, a rotary polygon mirror, an optical deflector that deflects light emitted from the light source, and deflection by the optical deflector. A scanning optical system that guides the emitted light to the surface to be scanned, and a housing to which the light source, the optical deflector, and the scanning optical system are attached, and the housing is a rotating shaft of the rotary polygon mirror Including an attachment portion of the optical deflector having a first reference surface and a second reference surface having different positions with respect to directions, and the optical deflector is attached to one of the first reference surface and the second reference surface. In the mounting portion, the first optical deflector having the first reference surface as a reference surface and the second reference surface as the reference surface, the dimensions in the rotation axis direction are from the first optical deflector. One of the smaller second optical deflectors is attached, and the rotation axis direction In this regard, the second reference plane is higher than the first reference plane in correspondence with a difference in dimension between the first optical deflector and the second optical deflector in the rotation axis direction. This is an optical scanning device.

  According to the optical scanning device of the present invention, it is possible to reduce the cost without deteriorating the imaging performance of the scanning optical system.

1 is a diagram for explaining a schematic configuration of a multifunction peripheral according to an embodiment of the present invention. FIG. FIG. 2 is a diagram (part 1) for explaining the configuration of the optical scanning device in FIG. 1; FIG. 3 is a second diagram for explaining the configuration of the optical scanning device in FIG. 1; FIG. 3 is a third diagram for explaining the configuration of the optical scanning device in FIG. 1; FIG. 4 is a fourth diagram for explaining the configuration of the optical scanning device in FIG. 1; It is a figure for demonstrating the scanning start position and scanning end position in a scanning area | region. It is a figure for demonstrating angle (theta) in which the advancing direction (incident direction) of the light beam which injects into an optical deflector, and a reference axis direction make. It is a figure for demonstrating the light beam width din of the light beam which injects into an optical deflector. It is a figure for demonstrating the inscribed circle of a rotary polygon mirror. It is a figure for demonstrating the incident light beam and reflected light beam with respect to a rotary polygon mirror in the timing which the light beam deflected by the optical deflector heads to the scanning start position in the scanning area | region of a photosensitive drum. It is a figure for demonstrating the incident light beam and reflected light beam with respect to a rotary polygon mirror in the timing which the light beam deflected by the optical deflector goes to the center position of the scanning area | region of a photosensitive drum. It is a figure for demonstrating the incident light beam and reflected light beam with respect to a rotary polygon mirror in the timing which the light beam deflected by the optical deflector goes to the scanning end position in the scanning area | region of a photosensitive drum. It is a figure for demonstrating a scanning angle of view. It is a figure for demonstrating the deflector attachment part provided in the optical housing. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a perspective view of a deflector attachment part. FIG. 18A and FIG. 18B are diagrams for explaining the first reference plane, respectively. FIG. 19A and FIG. 19B are diagrams for explaining the second reference plane, respectively. It is FIG. (1) for demonstrating the optical deflector 2104A for low speed rotation. It is FIG. (2) for demonstrating optical deflector 2104A for low speed rotations. 3 is a YZ sectional view of the rotating member 10. FIG. It is a figure for demonstrating the state which removed the rotation member 10 in FIG. It is a figure for demonstrating a motor. It is FIG. (1) for demonstrating the optical deflector 2104B for high speed rotation. It is FIG. (2) for demonstrating the optical deflector 2104B for high speed rotation. 3 is a YZ sectional view of the rotating member 11. FIG. It is a figure for demonstrating the state which removed the rotation member 11 in FIG. It is a figure for demonstrating the difference between optical deflector 2104A and optical deflector 2104B. It is FIG. (1) for demonstrating the screw fixation of optical deflector 2104A. It is FIG. (2) for demonstrating the screw fixation of optical deflector 2104A. It is a figure for demonstrating the state in which the optical deflector 2104A is attached to the deflector attachment part. It is a figure for demonstrating the sealing member. It is FIG. (1) for demonstrating the screw fixation of the optical deflector 2104B. It is FIG. (2) for demonstrating the screw fixation of the optical deflector 2104B. It is a figure for demonstrating the state in which the optical deflector 2104B is attached to the deflector attachment part. FIG. 6 is a diagram (No. 1) for describing a difference Dz between the first reference surface and the second reference surface in the Z-axis direction. FIG. 10 is a diagram (No. 2) for explaining a difference Dz between the first reference surface and the second reference surface in the Z-axis direction. It is a figure for demonstrating the heat radiating member. It is AA sectional drawing of FIG. It is a figure for demonstrating the modification 1 of a deflector attachment part. It is a figure for demonstrating the modification 2 of a deflector attachment part. It is a figure for demonstrating the modification 3 of a deflector attachment part.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a schematic configuration of a multifunction machine 2000 as an image forming apparatus according to an embodiment.

  The multifunction machine 2000 has functions of a copying machine, a printer, and a facsimile machine, and includes a main body device 1001, a reading device 1002, an automatic document feeder 1003, and the like.

  The main body device 1001 is a tandem multicolor printer that forms a full-color image by superimposing four colors (black, cyan, magenta, and yellow), and includes an optical scanning device 2010 and four photosensitive drums (2030a and 2030b). , 2030c, 2030d), four cleaning units (2031a, 2031b, 2031c, 2031d), four charging devices (2032a, 2032b, 2032c, 2032d), four developing rollers (2033a, 2033b, 2033c, 2033d), intermediate transfer A belt 2040, a transfer roller 2042, a fixing roller 2050, a paper feed roller 2054, a paper discharge roller 2058, a paper feed tray 2060, a paper discharge tray 2070, a communication control device 2080, and a printer control device 2090 that comprehensively controls the above components. It is equipped with a.

  The reading device 1002 is disposed on the upper side of the main body device 1001 and reads a document. That is, the reading device 1002 is a so-called scanner device. The image information of the document read here is sent to the printer control device 2090 of the main body device 1001.

  The automatic document feeder 1003 is disposed on the upper side of the reading device 1002 and sends out the set document toward the reading device 1002. This automatic document feeder 1003 is generally called an ADF (Auto Document Feeder).

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network and data communication via a public line.

  The printer control device 2090 includes a CPU, a program written in a code decipherable by the CPU, a ROM storing various data used when executing the program, a RAM as a working memory, an analog signal An AD converter circuit for converting the signal into a digital signal. Then, the printer control device 2090 sends image information from the reading device 1002 or image information via the communication control device 2080 to the optical scanning device 2010.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, and the cleaning unit 2031a are used as a set, and constitute an image forming station (hereinafter also referred to as “K station” for convenience) that forms a black image.

  The photosensitive drum 2030b, the charging device 2032b, the developing roller 2033b, and the cleaning unit 2031b are used as a set, and constitute an image forming station (hereinafter also referred to as “M station” for convenience) that forms a magenta image.

  The photosensitive drum 2030c, the charging device 2032c, the developing roller 2033c, and the cleaning unit 2031c are used as a set, and constitute an image forming station (hereinafter also referred to as “C station” for convenience) that forms a cyan image.

  The photosensitive drum 2030d, the charging device 2032d, the developing roller 2033d, and the cleaning unit 2031d are used as a set, and constitute an image forming station (hereinafter also referred to as “Y station” for convenience) that forms a yellow image.

  Each photosensitive drum has a photosensitive layer formed on the surface thereof. Each photosensitive drum is rotated in the direction of the arrow in the plane of FIG. 1 by a rotation mechanism (not shown).

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

  The optical scanning device 2010 is charged correspondingly by light modulated for each color based on multi-color image information (black image information, cyan image information, magenta image information, yellow image information) from the printer control device 2090. Each surface of the photosensitive drum is scanned. Thereby, a latent image corresponding to the image information is formed on the surface of each photosensitive drum. That is, the surface of each photoconductive drum is a surface to be scanned. Each photosensitive drum is an image carrier. Therefore, hereinafter, the surface of each photosensitive drum is also referred to as a scanned surface or an image surface. The latent image formed here moves in the direction of the corresponding developing device as the photosensitive drum rotates. The configuration of the optical scanning device 2010 will be described later.

  By the way, in each photosensitive drum, an area scanned with light is called a “scanning area”, and an area in which image information is written in the scanning area is an “effective scanning area”, “image forming area”, “ This is called “effective image area”. In addition, the direction parallel to the rotation axis of each photosensitive drum is referred to as “main scanning direction”, and the rotation direction of the photosensitive drum is referred to as “sub-scanning direction”.

  As each developing roller rotates, toner from a corresponding toner cartridge (not shown) is thinly and uniformly applied to the surface thereof. Then, when the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves only to a portion irradiated with light on the surface and adheres to the surface. In other words, each developing roller causes toner to adhere to the latent image formed on the surface of the corresponding photosensitive drum so as to be visualized. Here, the toner-attached image (toner image) moves in the direction of the intermediate transfer belt 2040 as the photosensitive drum rotates.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the intermediate transfer belt 2040 at a predetermined timing, and are superimposed to form a color image.

  Recording paper is stored in the paper feed tray 2060. A paper feed roller 2054 is disposed in the vicinity of the paper feed tray 2060. The paper feed roller 2054 takes out the recording paper one by one from the paper feed tray 2060. The recording paper is sent out toward the gap between the intermediate transfer belt 2040 and the transfer roller 2042 at a predetermined timing. As a result, the color image on the intermediate transfer belt 2040 is transferred to the recording paper. The recording paper on which the color image is transferred is sent to the fixing roller 2050.

  In the fixing roller 2050, heat and pressure are applied to the recording paper, whereby the toner is fixed on the recording paper. The recording paper on which the toner is fixed is sent to the paper discharge tray 2070 via the paper discharge roller 2058 and is sequentially stacked on the paper discharge tray 2070.

  Each cleaning unit removes toner (residual toner) remaining on the surface of the corresponding photosensitive drum. The surface of the photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  Next, the configuration of the optical scanning device 2010 will be described.

  2 to 5 as an example, the optical scanning device 2010 includes two light sources (2200A, 2200B), four coupling lenses (2201a, 2201b, 2201c, 2201d), and four aperture plates (2202a, 2202b, 2202c, 2202d), four cylindrical lenses (2204a, 2204b, 2204c, 2204d), an optical deflector 2104, four scanning lenses (2105a, 2105b, 2105c, 2105d), eight folding mirrors (2106A, 2106B, 2107a, 2107b, 2107c, 2107d, 2108a, 2108d), a scanning control device (not shown), and the like. These are assembled at predetermined positions of the optical housing 2300.

  Here, in the XYZ three-dimensional orthogonal coordinate system, the direction along the longitudinal direction (rotation axis direction) of each photosensitive drum is defined as the Y-axis direction, and the direction along the rotation axis of the optical deflector 2104 is defined as the Z-axis direction. To do. In the following, for convenience, the direction corresponding to the main scanning direction of each optical member is abbreviated as “main scanning corresponding direction”, and the direction corresponding to the sub scanning direction is abbreviated as “sub scanning corresponding direction”.

  The light source 2200A and the light source 2200B are arranged at positions separated from each other in the X-axis direction. Each light source has two light emitting portions, and emits two light beams that are separated from each other at least in the Z-axis direction.

  Here, of the two light beams emitted from the light source 2200A, the light beam on the + Z side is referred to as “light beam La”, and the light beam on the −Z side is referred to as “light beam Lb”. Of the two light beams emitted from the light source 2200B, the light beam on the + Z side is referred to as “light beam Ld”, and the light beam on the −Z side is referred to as “light beam Lc”.

  The coupling lens 2201a is disposed on the optical path of the light beam La emitted from the light source 2200A, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201b is disposed on the optical path of the light beam Lb emitted from the light source 2200A, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201c is disposed on the optical path of the light beam Lc emitted from the light source 2200B, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201d is disposed on the optical path of the light beam Ld emitted from the light source 2200B, and makes the light beam a substantially parallel light beam.

  The cylindrical lens 2204a is disposed on the optical path of the light beam La via the coupling lens 2201a, and condenses the light beam in the Z-axis direction.

  The cylindrical lens 2204b is disposed on the optical path of the light beam Lb via the coupling lens 2201b, and condenses the light beam in the Z-axis direction.

  The cylindrical lens 2204c is disposed on the optical path of the light beam Lc via the coupling lens 2201c, and condenses the light beam in the Z-axis direction.

  The cylindrical lens 2204d is disposed on the optical path of the light beam Ld via the coupling lens 2201d, and condenses the light beam in the Z-axis direction.

  The aperture plate 2202a has an aperture and shapes the light beam La via the cylindrical lens 2204a.

  The aperture plate 2202b has an aperture and shapes the light beam Lb via the cylindrical lens 2204b.

  The aperture plate 2202c has an opening, and shapes the light beam Lc via the cylindrical lens 2204c.

  The aperture plate 2202d has an aperture and shapes the light beam Ld via the cylindrical lens 2204d.

  The light beam that has passed through the opening of each aperture plate enters the optical deflector 2104.

  The optical system disposed on the optical path between each light source and the optical deflector 2104 is also referred to as “pre-deflector optical system”.

  The optical deflector 2104 has a two-stage rotating polygon mirror. Each rotary polygon mirror is formed with six mirror surfaces, and each mirror surface is a deflection reflection surface. In the first-stage (lower) rotary polygon mirror, the light beam Lb that has passed through the opening of the aperture plate 2202b and the light beam Lc that has passed through the aperture of the aperture plate 2202c are deflected, respectively, and rotated in the second stage (upper). In the polygon mirror, the light beam La that has passed through the opening of the aperture plate 2202a and the light beam Ld that has passed through the opening of the aperture plate 2202d are respectively deflected.

  Here, the light beam La and the light beam Lb are deflected to the + X side of the optical deflector 2104, and the light beam Lc and the light beam Ld are deflected to the −X side of the optical deflector 2104.

  The scanning lens 2105 a and the scanning lens 2105 b are disposed on the + X side of the optical deflector 2104, and the scanning lens 2105 c and the scanning lens 2105 d are disposed on the −X side of the optical deflector 2104.

  The scanning lens 2105a and the scanning lens 2105b are stacked in the Z-axis direction, the scanning lens 2105a faces the second-stage rotary polygon mirror, and the scanning lens 2105b faces the first-stage rotary polygon mirror. The scanning lens 2105c and the scanning lens 2105d are stacked in the Z-axis direction, the scanning lens 2105c is opposed to the first-stage rotary polygon mirror, and the scanning lens 2105d is opposed to the second-stage rotary polygon mirror.

  The light beam La deflected by the optical deflector 2104 is irradiated onto the photosensitive drum 2030a through the scanning lens 2105a, the folding mirror 2106A, the folding mirror 2107a, and the folding mirror 2108a, thereby forming a light spot.

  The light beam Lb deflected by the optical deflector 2104 is irradiated onto the photosensitive drum 2030b through the scanning lens 2105b, the folding mirror 2106A, and the folding mirror 2107b, thereby forming a light spot.

  The light beam Lc deflected by the optical deflector 2104 is irradiated onto the photosensitive drum 2030c through the scanning lens 2105c, the folding mirror 2106B, and the folding mirror 2107c, thereby forming a light spot.

  The light beam Ld deflected by the optical deflector 2104 is irradiated onto the photosensitive drum 2030d through the scanning lens 2105d, the folding mirror 2106B, the folding mirror 2107d, and the folding mirror 2108d, thereby forming a light spot.

  The light spot on each photoconductive drum moves along the longitudinal direction (main scanning direction) of the photoconductive drum as the optical deflector 2104 rotates. The photosensitive drum 2030a and the photosensitive drum 2030b perform optical scanning in the −Y direction, and the photosensitive drum 2030c and the photosensitive drum 2030d perform optical scanning in the + Y direction (see FIG. 6).

  The optical system disposed on the optical path between the optical deflector 2104 and each photosensitive drum is also called a “scanning optical system”.

  Here, as shown in FIG. 7, when viewed from the Z-axis direction, an axis passing through the rotation center of the rotary polygon mirror and parallel to the X-axis is defined as a “reference axis”.

  When viewed from the Z-axis direction, the angle between the traveling direction of the light beam emitted from the light source and incident on the deflecting / reflecting surface and the reference axis is expressed as θin. Here, it is set to be θin = 55.0 °.

  Further, as shown in FIG. 8, when viewed from the Z-axis direction, the width of the light beam that has passed through the opening of the aperture plate is expressed as din. This light beam enters the optical deflector 2104. Here, din is set to be 3.8 mm.

  The diameter of a circle (see FIG. 9) inscribed in the rotary polygon mirror is 18 mm. Therefore, the length of the perpendicular drawn from the rotation center of the rotary polygon mirror to each deflecting reflection surface is 9 mm. When it is necessary to distinguish between the six deflecting reflecting surfaces, they are referred to as surface 1, surface 2, surface 3, surface 4, surface 5, and surface 6 in the counterclockwise direction.

  Next, a light beam emitted from the light source 2200A and incident on the optical deflector 2104 and a light beam deflected by the optical deflector 2104 will be described with reference to FIGS. Here, it is assumed that the light beam reflected by the surface 1 of the rotary polygon mirror goes to the scanning area of the corresponding photosensitive drum.

  FIG. 10 shows the incident light beam and the reflected light beam with respect to the rotary polygon mirror at the timing when the light beam deflected by the optical deflector 2104 moves toward the scanning start position in the scanning region of the corresponding photosensitive drum. At this time, not all of the light beam incident on the optical deflector 2104 is incident on the surface 1 of the rotary polygon mirror, but a part of the light beam incident on the optical deflector 2104 is set to be incident on the surface 6. . Therefore, the width ds of the light beam reflected by the surface 1 of the rotary polygon mirror and traveling toward the scanning start position of the corresponding photosensitive drum is smaller than the width din of the light beam incident on the optical deflector 2104. That is, at this time, in the optical deflector 2104, a part of the incident light flux is “scratched”. Here, ds = 3.5 mm is set.

  At this time, the angle θs between the traveling direction of the light beam reflected by the surface 1 of the rotary polygon mirror and the reference axis is 40.0 °. The inclination angle θ1 of the surface 1 with respect to the reference axis is 42.5 °.

  FIG. 11 shows the incident light beam and the reflected light beam with respect to the rotary polygon mirror at the timing when the light beam deflected by the optical deflector 2104 goes to the center position of the scanning region of the corresponding photosensitive drum. At this time, all the light beams incident on the optical deflector 2104 are set to be incident on the surface 1 of the rotary polygon mirror. Therefore, the width dc of the light beam reflected by the surface 1 of the rotary polygon mirror and going to the center position of the scanning region of the corresponding photosensitive drum is the same as the width din of the light beam incident on the optical deflector 2104. That is, at this time, the optical deflector 2104 does not “jump” the incident light beam. At this time, the inclination angle θ1 of the surface 1 with respect to the reference axis is 62.5 °.

  FIG. 12 shows the incident light beam and the reflected light beam with respect to the rotary polygon mirror at the timing when the light beam deflected by the optical deflector 2104 moves toward the scanning end position in the scanning region of the corresponding photosensitive drum. At this time, not all the light beams incident on the optical deflector 2104 are incident on the surface 1 of the rotary polygon mirror, but a part of the light beams incident on the optical deflector 2104 are set to be incident on the surface 2. . Therefore, the width de of the light beam reflected by the surface 1 of the rotary polygon mirror and traveling toward the scanning end position of the corresponding photosensitive drum is smaller than the width din of the light beam incident on the optical deflector 2104. That is, at this time, in the optical deflector 2104, a part of the incident light flux is “scratched”. Here, it is set so that de = 3.5 mm.

  At this time, the angle θe formed between the traveling direction of the light beam reflected by the surface 1 of the rotary polygon mirror and the reference axis is 40.0 °. The inclination angle θ1 of the surface 1 with respect to the reference axis is 82.5 °.

  | Θs | + | θe | is an angle corresponding to a so-called scanning angle of view (see FIG. 13), and is 80.0 ° here. Also, θs and θe are called “scanning half angle of view”. Here, | θs | = | θe |.

  Here, the scanning start position in the scanning area of the photosensitive drum is one side end of the scanning area in the main scanning direction, and the scanning end position in the scanning area of the photosensitive drum is in the scanning area in the main scanning direction. It is the other end.

  The luminous flux emitted from the light source 2200B and incident on the optical deflector 2104 and the luminous flux deflected by the optical deflector 2104 are set in the same manner as the luminous flux emitted from the light source 2200A.

  By the way, there are an underfilled type and an overfilled type as a method of making laser light enter the rotary polygon mirror. Hereinafter, for convenience, the underfilled type is also referred to as “UF type” and the overfilled type is also referred to as “OF type”.

  In the UF type, the width of the incident light is smaller than the length of the deflecting / reflecting surface in the direction corresponding to the main scanning direction (see, for example, JP-A-2005-92129). In this case, all of the incident light is guided to the photosensitive drum.

  In the OF type, the width of the incident light is larger than the length of the deflection reflection surface in the direction corresponding to the main scanning direction (see, for example, Japanese Patent Application Laid-Open Nos. 10-206778 and 2003-279877). In this case, ambient light in the incident light is not guided to the photosensitive drum.

  In the conventional UF type optical scanning device, in order to cope with high-speed image formation and high pixel density, it is necessary to increase the length of the deflection reflection surface in the direction corresponding to the main scanning direction. It is necessary to reduce the number of faces in the rotating polygon mirror or increase the diameter of the inscribed circle in the rotating polygon mirror.

  However, if the number of surfaces is reduced, there is a disadvantage that the number of rotations of the rotary polygon mirror must be increased. On the other hand, when the diameter of the inscribed circle is increased, the windage loss of the rotary polygon mirror increases and there is a disadvantage that the power consumption increases. It is conceivable to increase the number of light sources and increase the number of beams deflected by one deflecting / reflecting surface. However, as the number of light sources increases, the drive circuit of the light source increases in size, resulting in an increase in cost.

  Further, in the conventional OF type optical scanning device, it is necessary to use 10 or more rotating polygonal mirrors in order to cope with high-speed image formation and high pixel density, so the scanning angle of view becomes small. There is a disadvantage that the optical scanning device is increased in size. Moreover, since the peripheral part of the light beam is not used, there is a disadvantage that the light utilization efficiency is low.

  In the optical scanning device 2010 in this embodiment, (1) the rotating polygon mirror can be made smaller than the conventional UF type optical scanning device. Therefore, it becomes possible to rotate the rotary polygon mirror at a high speed without increasing the power consumption. Further, it is possible to cope with a high-speed image formation and a high pixel density without increasing the number of light sources, that is, without increasing the cost.

  Further, in the optical scanning device 2010 in this embodiment, (2) the scanning angle of view can be made larger than that of the conventional OF type optical scanning device. Therefore, it is possible to cope with an increase in image formation speed and an increase in pixel density without causing an increase in size.

  Incidentally, the optical housing 2300 is a resin molded product using a mold. The optical housing 2300 has a thickness (plate thickness) t of about 2 mm, and ribs are provided at a plurality of locations to ensure strength.

  14 to 17 show a mounting portion (hereinafter also referred to as “deflector mounting portion” for convenience) 2310 of the optical deflector 2104 in the optical housing 2300 of the present embodiment. 15 is a cross-sectional view taken along the line AA in FIG. 14, and FIG. 16 is a cross-sectional view taken along the line BB in FIG. FIG. 17 is a perspective view of the deflector mounting portion 2310.

  The deflector mounting portion 2310 can be attached with either an optical deflector for low speed rotation or an optical deflector for high speed rotation.

  The deflector mounting portion 2310 has a shape in which the central portion is recessed toward the −Z side. Here, the indented portion is referred to as a surface P1, and the portion surrounding the surface P1 is referred to as a surface P2. Both the surface P1 and the surface P2 are substantially parallel to a plane orthogonal to the Z axis.

  The surface P1 is provided with four first positioning portions (201, 202, 203, 204) for positioning the light deflector for low-speed rotation in the Z-axis direction. Each first positioning portion is a portion protruding to the + Z side with respect to the surface P1, and a screw hole is formed at the center. Here, the protrusion amount h1 (see FIGS. 18A and 18B) of each first positioning portion with respect to the surface P1 is about 0.5 mm.

  The surface on the + Z side of each first positioning portion is parallel to a plane orthogonal to the Z axis, and the position in the Z axis direction is the same. That is, the surfaces of the four first positioning portions on the + Z side are on the same plane orthogonal to the Z axis. Hereinafter, the surface on the + Z side of each first positioning portion is also referred to as a “first reference surface”. Here, each first reference plane has a square shape with a side length of about 10 mm.

  Further, four second positioning portions (205, 206, 207, 208) for positioning the optical deflector for high-speed rotation in the Z-axis direction are provided on the surface P2. Each second positioning portion is a portion protruding to the + Z side with respect to the surface P2, and a screw hole is formed at the center. Here, the protrusion amount h2 (see FIGS. 19A and 19B) with respect to the surface P2 of each second positioning portion is about 0.5 mm.

  The surface on the + Z side of each second positioning portion is parallel to a plane orthogonal to the Z axis, and the position in the Z axis direction is the same. That is, the + Z side surfaces of the four second positioning portions are on the same plane orthogonal to the Z axis. Hereinafter, the surface on the + Z side of each second positioning portion is also referred to as a “second reference surface”. Here, each second reference plane has a square shape with a side length of about 10 mm.

  Here, an optical deflector for low-speed rotation (referred to as an optical deflector 2104A) will be described. The optical deflector 2104A is a low-cost optical deflector for a relatively low speed rotation of 30000 to 40000 rotations.

  As shown in FIG. 20 and FIG. 21 as an example, the optical deflector 2104A includes a rotating member 10, a circuit board 41, a drive IC 43, a connector 44, and the like.

  FIG. 22 shows a YZ cross section of the rotating member 10. The rotating member 10 includes a rotating polygon mirror 12, a holding member 13, a shaft 15, a rotor 31, and the like.

  The rotary polygon mirror 12 is made of an aluminum alloy, and the deflection reflection surface is processed simultaneously by a plurality of rotary polygon mirrors to reduce the cost. Here, the diameter of the inscribed circle of the rotary polygon mirror 12 is 18 mm.

  The holding member 13 is a steel member that holds the rotary polygon mirror 12. The shaft 15 is a rod-shaped member made of stainless steel, and is attached to the holding member 13. The rotor 31 is a bonded magnet using a resin as a binder, and is magnetized in the radial direction.

  FIG. 23 shows a state where the rotating member 10 is removed in FIG. A bearing member 21 into which the shaft 15 is inserted is fixed to the circuit board 41. A stator core 32 is attached to the bearing member 21, and a winding coil 33 is attached to the stator core 32.

  The rotor 31, the stator core 32, and the winding coil 33 constitute a motor (see FIG. 24). This motor is an outer rotor type DC brushless motor in which a rotor 31 is disposed in the vicinity of an outer peripheral portion of a stator core 32. The rotor 31 rotates by generating rotational torque with the outer peripheral portion of the stator core 32.

  The drive IC 43 refers to the output signal of the hall element (not shown) as the position signal of the rotating member 10 and switches the excitation of the winding coil 33. Thereby, rotation of the rotation member 10 is continued.

  A harness (not shown) is connected to the connector 44, and power is supplied from the scanning control device, the motor is started and stopped, and control signals such as the number of revolutions are input and output.

  On the circuit board 41, a wiring pattern for electrically connecting the winding coil 33 and the driving IC 43, a wiring pattern for electrically connecting the Hall element and the driving IC 43, and an electrical connection between the connector 44, the Hall element and the driving IC 43, A wiring pattern or the like connected to is formed.

  In the optical deflector 2104A, the distance D1 (see FIG. 21) between the −Z side surface of the circuit board 41 and the center of the −Z side deflection reflection surface of the rotary polygon mirror 12 is 11 mm.

  Next, an optical deflector for high-speed rotation (referred to as an optical deflector 2104B) will be described. The optical deflector 2104B has high durability even when used at a rotational speed of 30000 to 40000 or more.

  As an example, the optical deflector 2104B includes a rotating member 11, a circuit board 42, a drive IC 43, a connector 44, and the like, as shown in FIGS.

  FIG. 27 shows a YZ cross section of the rotating member 11. The rotating member 10 includes a rotating polygon mirror 16, a shaft 15, a rotor 31, and the like.

  The rotary polygon mirror 16 is made of an aluminum alloy, is processed for each single item, and is more expensive than the rotary polygon mirror 12 of the optical deflector 2104A. Here, the diameter of the inscribed circle of the rotary polygon mirror 16 is 18 mm.

  The shaft 15 and the rotor 31 are attached to the rotary polygon mirror 16. The rotating member 11 has a lower center of gravity than the rotating member 10 of the optical deflector 2104A.

  FIG. 28 shows a state where the rotating member 11 is removed in FIG. A bearing member 22 into which the shaft 15 is inserted is fixed to the circuit board 42. A stator core 32 is attached to the bearing member 22, and a winding coil 33 is attached to the stator core 32.

  The bearing member 22 is set to withstand high-speed rotation as compared with the bearing member 21 of the optical deflector 2104A and is expensive. That is, the optical deflector 2104B is more expensive than the optical deflector 2104A.

  In the optical deflector 2104B, the distance D2 (see FIG. 25) between the −Z side surface of the circuit board 42 and the center of the −Z side deflection reflection surface of the rotary polygon mirror 16 is 3 mm.

  When the optical deflector 2104A and the optical deflector 2104B are compared, the length (height) in the Z-axis direction is different as shown in FIG. Here, with respect to the Z-axis direction, the position of the deflecting / reflecting surface in the optical deflector 2104B is 8 (= 11−3) mm lower than the position of the deflecting / reflecting surface in the optical deflector 2104A.

  In the optical deflector 2104A, the −Z side surface of the circuit board 41 is placed on the four first reference surfaces and fixed with screws (see FIGS. 30 and 31). A state where the optical deflector 2104A is fixed to the deflector mounting portion 2310 is shown in FIG.

  The optical housing 2300 is provided with dust-proof glass on a window from which light is emitted toward the photosensitive drum, and further a lid member in order to prevent clouding of the rotating polygon mirror, contamination of the optical member and accompanying optical performance deterioration. And the inside of the optical housing 2300 has a substantially sealed structure. Therefore, if the screw holes of the four second positioning portions (205, 206, 207, 208) are through-holes, dust from outside can be obtained by closing the screw holes with the seal member 40 as shown in FIG. Can be prevented from entering. For example, a double-sided tape may be attached to a resin sheet having a diameter of about 10 mm. Instead of the seal member 40, the screw hole may be filled with an adhesive.

  In the optical deflector 2104B, the surface on the −Z side of the circuit board 42 is placed on the four second reference surfaces and fixed with screws (see FIGS. 34 and 35). A state where the optical deflector 2104B is fixed to the deflector mounting portion 2310 is shown in FIG.

  In this embodiment, the position difference Dz (see FIG. 37) in the Z-axis direction between the first reference surface and the second reference surface is set to 8 mm. Therefore, as shown in FIG. 38, the position of the deflection reflection surface in the Z-axis direction can be the same regardless of whether the optical deflector 2104A is attached or the optical deflector 2104B is attached. As a result, a desired imaging characteristic can be obtained regardless of which of the optical deflector 2104A and the optical deflector 2104B is attached.

  By the way, in recent image forming apparatuses such as a multi-function printer (MFP), a copying machine, and a printer, a plurality of machines having different printing speeds are made into the same model group, and a low-speed machine (for example, 20 sheets / minute). To high-speed machines (for example, 60 sheets / minute) are manufactured on the same platform. In an optical scanning device in a plurality of machines having different printing speeds, for example, an optical deflector in which a rotating polygon mirror rotates at 20000 rpm to 60000 rpm is used, and the rotating polygon mirror rotates at a rotation speed corresponding to the printing speed.

  However, as described above, the optical deflector for low-speed rotation and the optical deflector for high-speed rotation have different rotating member structures, and the height of the rotary polygon mirror from the mounting reference plane is different. In one model group including up to high-speed machines, high-speed optical deflectors were used for low-speed machines, resulting in high costs.

  Patent Document 1 discloses a deflector mounting structure in which different types of deflectors are attached to a common housing via a connection plate, and a scanning optical device including the mounting structure. In this case, the direction perpendicular to the mounting surface of the housing and the direction of the rotation axis of the optical deflector are to coincide with each other, but an inclination error is added by interposing the connection plate, and the imaging performance of the scanning optical system deteriorates. There was a fear.

  In the present embodiment, the first reference surface and the second reference surface that are parallel to the surface orthogonal to the Z-axis direction are provided at different positions with respect to the Z-axis direction. In this case, there is no possibility that the imaging performance of the scanning optical system is deteriorated regardless of which one of the light deflector for low speed rotation and the light deflector for high speed rotation is used.

  In the present embodiment, the plane including the four second reference planes having a larger distance between the reference planes is larger in the Z axis than the plane including the four first reference planes and the plane including the four second reference planes. There is little error with respect to the plane orthogonal to Therefore, the tilt error of the rotation axis of the optical deflector can be suppressed smaller when the optical deflector is attached to the second positioning portion than when the optical deflector is attached to the first positioning portion.

  That is, the second reference surface is also suitable as an attachment reference surface for an optical deflector for forming a high resolution image.

  As described above, the optical scanning device 2010 is an optical scanning device that can be used in common except for the optical deflector, while corresponding to models with different imaging performance specifications, or with future imaging performance improvement and cost reduction. is there.

  When the optical deflector 2104B is attached, the heat dissipation member 500 may be placed on the first reference surface so as to be in contact with the −Z side surface of the circuit board 42 (see FIGS. 39 and 40). . 40 is a cross-sectional view taken along the line AA in FIG. Thereby, even if the heat capacity increases and the amount of heat generated by high-speed rotation increases, the temperature rise of the optical deflector 2104B can be suppressed. As a result, an increase in unbalanced vibration of the rotating member in the optical deflector 2104B is reduced, and image deterioration factors such as variations in scanning position and banding due to the vibration can be suppressed.

  As the heat radiating member 500, an aluminum alloy plate, a steel plate, a resin containing metal powder, ceramics having excellent thermal conductivity, or the like can be used. Further, the heat radiating member 500 may be attached to the −Z side surface of the circuit board 42 of the optical deflector 2104B.

  Further, a vibration isolating member may be placed on the first reference surface so as to come into contact with the −Z side surface of the circuit board 42 when the optical deflector 2104B is attached. Thereby, even if it rotates at high speed, vibration and noise can be reduced. As the vibration isolating member, a damping steel plate in which a plurality of steel plates are laminated with a resin interposed therebetween can be used. The vibration isolating member may be attached to the surface on the −Z side of the circuit board 42.

  As described above, according to the optical scanning device 2010 according to the present embodiment, an optical deflector corresponding to the printing speed is selected without interposing a connecting plate or the like in the deflector mounting portion 2310 of the optical housing 2300. Can be attached. In this case, it is possible to suppress degradation of the imaging performance of the scanning optical system regardless of which optical deflector is selected. That is, the cost can be reduced without deteriorating the imaging performance of the scanning optical system.

  In addition, at the timing when the light beam reflected by the rotating polygon mirror is directed to the center of the scanning area of the corresponding photosensitive drum, all the light beams incident on the rotating polygon mirror are reflected by one reflecting surface, and the rotating polygon mirror is used. At the timing when the light beam reflected by the light beam travels toward each end of the scanning area of the corresponding photosensitive drum, a part of the light beam incident on the rotary polygon mirror is reflected by one reflecting surface, and the rest is reflected by the other reflecting surface. It is set to reflect on the surface. In this case, it is possible to reduce the size of the rotary polygon mirror and increase the scanning field angle.

  Therefore, the optical scanning device 2010 can further reduce the size and speed at a low cost without degrading the image quality.

  Since the multifunction machine 2000 includes the optical scanning device 2010, as a result, it is possible to reduce the size and speed at a low cost without deteriorating the image (output image) quality.

  In the above embodiment, the case where the shape of each reference surface is a square has been described. However, the present invention is not limited to this. For example, the shape of each reference surface may be circular.

  Further, the size of each reference plane is not limited to the above embodiment.

  Moreover, although the said embodiment demonstrated the case where the shape of each reference plane was the same, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the screw hole was provided in each reference surface, it is not limited to this. As an example, as shown in FIG. 41, screw holes may be provided at positions different from the reference plane.

  Moreover, although the said embodiment demonstrated the case where four 1st reference planes were provided, it is not limited to this. Three or more first reference surfaces may be provided, and two of them may be provided with a rotation shaft (shaft) of the rotating member interposed therebetween.

  Moreover, although the said embodiment demonstrated the case where four 2nd reference planes were provided, it is not limited to this. Three or more second reference surfaces may be provided, and two of them may be provided with a rotation shaft (shaft) of the rotating member interposed therebetween.

  Moreover, in the said embodiment, two 1st reference planes may be connected (refer FIG. 42). Similarly, two second reference planes may be connected (see FIG. 42).

  Moreover, in the said embodiment, the four 1st reference planes may be connected (refer FIG. 43). Similarly, four second reference planes may be connected (see FIG. 43).

  Moreover, the dimension in the said embodiment is an example, and is not limited to this.

  In the above-described embodiment, the case where the incident light beam is “kept” by the optical deflector 2104 at both the timing toward the scanning start position and the timing toward the scanning end position in the scanning region has been described. However, the present invention is not limited to this. Instead, the incident light beam may be “kept” by the optical deflector 2104 at either the timing toward the scanning start position or the timing toward the scanning end position in the scanning region.

  Moreover, although the said embodiment demonstrated the case where din was 3.8 mm, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the diameter of the circle | round | yen inscribed in a rotating polygon mirror was 18 mm, it is not limited to this.

  Moreover, although the said embodiment demonstrated the case where the mirror surface of 6 surfaces was formed in the rotating polygon mirror, it is not limited to this.

  Further, in the above-described embodiment, the amount of “deletion” of the light beam toward the one side end of the scanning region by the optical deflector and the “deletion” of the light beam toward the other end of the scanning region by the optical deflector. The amount may be different.

  In the above embodiment, the case of | θs | = | θe | has been described. However, the present invention is not limited to this.

  Moreover, in the said embodiment, the system which makes a rotary polygon mirror inject a laser beam may be a conventional UF type, and may be a conventional OF type.

  In the above embodiment, a monolithic edge emitting laser array or a surface emitting laser array may be used as the light source.

  In the above embodiment, the case where the number of photosensitive drums is four has been described. However, the present invention is not limited to this.

  In the above embodiment, the case where the main body apparatus 1001 is a multicolor printer has been described. However, the present invention is not limited to this, and may be a monochrome printer.

  Moreover, although the said embodiment demonstrated the case where two light sources each having two light emission parts were used, it is not limited to this. For example, four light sources each having one light emitting unit may be used. Alternatively, two light sources each having one light emitting unit may be used, and the light beam emitted from each light source may be divided into two.

  In the above-described embodiment, the case where the image forming apparatus is a multifunction peripheral has been described. However, the present invention is not limited to this. The image forming apparatus may be a single copying machine, a printer, and a facsimile machine.

  Further, an image forming apparatus that directly irradiates laser light onto a medium (for example, paper) that develops color with laser light may be used.

  Further, an image forming apparatus using a silver salt film as the image carrier may be used. In this case, a latent image is formed on the silver salt film by optical scanning, and this latent image can be visualized by a process equivalent to a developing process in a normal silver salt photographic process. Then, it can be transferred to photographic paper by a process equivalent to a printing process in a normal silver salt photographic process. Such an image forming apparatus can be implemented as an optical plate making apparatus or an optical drawing apparatus that draws a CT scan image or the like.

  DESCRIPTION OF SYMBOLS 10 ... Rotating member, 11 ... Rotating member, 12 ... Rotating polygon mirror, 13 ... Holding member, 15 ... Shaft, 21 ... Bearing member, 22 ... Bearing member, 31 ... Rotor, 32 ... Stator core, 33 ... Winding coil, 40 ... Sealing member, 41 ... Circuit board, 42 ... Circuit board, 43 ... Drive IC, 44 ... Connector, 201-204 ... First positioning part, 205-208 ... Second positioning part, 2000 ... Multifunction machine (image forming apparatus) 2010 ... Optical scanning devices, 2030a, 2030b, 2030c, 2030d ... Photosensitive drum (image carrier), 2104 ... Optical deflectors, 2105a, 2105b, 2105c, 2105d ... Scanning lens (part of scanning optical system), 2200A , 2200B ... light source, 2201a, 2201b, 2201c, 2201d ... coupling lens, 2202a, 2202b, 202c, 2202 d ... aperture plate, 2204a, 2204 b, 2204 c, 2204 d ... cylindrical lens 2300 ... optical housing (housing), 2310 ... deflector mounting portion (mounting portion).

JP 2013-040882 A

Claims (9)

An optical scanning device that scans a surface to be scanned with light,
A light source;
An optical deflector having a rotating polygon mirror and deflecting light emitted from the light source;
A scanning optical system for guiding the light deflected by the optical deflector to the scanned surface;
A housing to which the light source, the optical deflector, and the scanning optical system are attached;
The housing includes a mounting portion for the optical deflector having a first reference surface and a second reference surface that have different positions in the rotation axis direction of the rotary polygon mirror, and the optical deflector includes the first reference surface. And attached to one of the second reference planes,
The mounting portion has a first optical deflector that uses the first reference surface as a reference surface and a second reference surface that serves as a reference surface, and has a smaller dimension in the rotation axis direction than the first optical deflector. One of the second light deflectors is attached,
With respect to the rotation axis direction, the second reference plane is higher than the first reference plane, corresponding to a difference in dimensions with respect to the rotation axis direction of the first optical deflector and the second optical deflector. optical scanning device you wherein a. When orthogonally projected on a plane perpendicular to the rotation axis direction, the second reference surface, the optical scanning apparatus according to claim 1, characterized in that surrounds the first reference plane. The second optical deflector is attached to the second reference plane;
The optical scanning device according to claim 1 or 2, characterized by further comprising a heat radiation member provided between the second optical deflector and the first reference surface. The second optical deflector is attached to the second reference plane;
Wherein the first reference surface is provided between the second optical deflector, the optical scanning device according to claim 1 or 2, characterized by further comprising suppressing member vibration or noise. The second reference surface has a screw hole for attaching the second optical deflector;
The first optical deflector is attached to the first reference plane;
The optical scanning device according to any one of claims 1 to 4, further comprising a seal member for sealing the threaded hole of the second reference plane. The first optical deflector is an optical deflector for low-speed rotation, the second optical deflector any one of claims 1-5, characterized in that an optical deflector for high-speed rotation The optical scanning device according to 1. 6. The optical scanning device according to claim 1 , wherein the second optical deflector is an optical deflector having a higher resolution than the first optical deflector. The first reference surface and the second reference surface is divided into at least three, two of which in any one of claims 1 to 7, characterized in that provided across the rotary shaft The optical scanning device described. An image carrier;
Image forming apparatus and a light scanning apparatus according to any one of claims 1-8 for scanning by light modulated with said image bearing member by the image information.

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