JP4340569B2 - Optical element holding member, optical scanning device, and image forming apparatus - Google Patents

Description

  The present invention relates to an optical element holding member that houses an optical scanning device that deflects a plurality of light beams modulated in accordance with an image signal and focuses each deflected beam as a light spot on a surface to be scanned. The present invention relates to an optical scanning apparatus and an image forming apparatus provided with members.

  In an image forming apparatus such as a digital copying machine, a printer, or a facsimile, a light beam modulated in accordance with an image signal is deflected to be condensed as a light spot on a surface to be scanned such as a photoconductor, and is latent on the surface to be scanned. It is widely practiced to form an image, develop the latent image, and transfer it to a transfer material such as recording paper. Along with the digitalization of copiers, digitalization is also progressing in copiers that support wide paper such as A1 and A0. In response to the demand for higher image quality, a light beam such as a laser is used like a polygon mirror. An optical writing type in which scanning is changed by a deflector has been put into practical use. However, in such an optical writing system, for example, in writing by light beam scanning with an A0 width, since the scanning width is large, the lens becomes large and very expensive. Furthermore, the length of the reflection mirror becomes long, and the housing for holding the lens, the reflection mirror, etc. becomes large, and not only the parts but also the mold cost for manufacturing the housing becomes enormous. Therefore, for example, Patent Documents 1 to 3 disclose a method of obtaining a wide scanning width by connecting two writing systems in the main scanning direction (laser beam scanning direction).

  Such an optical scanning device in which two writing systems are connected in the main scanning direction will be described with reference to FIG. FIG. 3 is a schematic configuration diagram showing an example of an optical scanning scanning device corresponding to a wide width. On the light emitting side of the optical scanning device, light sources 1-1 and 1-2 configured by two semiconductor lasers (LD) as light sources for emitting light beams, and the emitted beams of these light sources 1-1 and 1-2 are used. On the other hand, collimating lenses 2-1 and 2-2 and cylindrical lenses 3-1 and 3-2 are arranged, respectively. A deflection having a plurality of deflection surfaces for deflecting two light beams respectively guided through the collimating lenses 2-1 and 2-2 and the cylindrical lenses 3-1 and 3-2 on the downstream side in the light irradiation direction. One polygon mirror 4 is provided as a means.

  Further, on the downstream side of the polygon mirror 4 in the light irradiation direction, a first imaging unit for imaging the two light beams deflected by the polygon mirror 4 on the photosensitive drum 10 which is the surface to be scanned is provided as a first imaging unit. Fθ lenses 5-1 and 5-2 and second Fθ lenses 6-1 and 6-2 are provided, respectively, and two reflections are provided for each of the two optical paths as scanning direction changing means. Mirrors, that is, first mirrors 7-1 and 7-2 and second mirrors 8-1 and 8-2 are provided. Further, on the optical path of the imaging optical system, the scanning light whose scanning direction is changed by the first mirrors 7-1 and 7-2 and the second mirrors 8-1 and 8-2 is applied to the photosensitive drum 10. Third mirrors 9-1 and 9-2 for guiding are provided.

  Thus, the wide optical scanning device (optical writing device) includes, for example, two optical writing systems, and the polygon mirror 4 is configured to be shared by the two optical writing systems. Here, the left half optical writing system from the polygon mirror 4 is referred to as a first writing system I, and the right half optical writing system is referred to as a second writing system II.

  In the first writing system I, the light source 1-1 emits laser light modulated according to the image signal under the control of a driving device (not shown), and this laser light is converted into parallel light by the collimator lens 2-1. The laser beam converted into parallel light by the collimator lens 2-1 enters the polygon mirror 4 through the cylindrical lens 3-1. The polygon mirror 4 is rotated by a motor (not shown), and the laser beam incident on the polygon mirror 4 is reflected by the deflection surface and deflected and scanned. The light beam changed and scanned by the polygon mirror 4 is changed from the constant angular velocity deflection to the constant velocity deflection by the first and second Fθ lenses 5-1 and 6-1, respectively, and then the third mirror 9-1. And is guided in the direction of the photosensitive drum 10, and scans from the center of a predetermined scanning position on the photosensitive drum 10 toward one end.

The second writing system II has the same configuration as the first writing system I, and is arranged at a position obtained by rotating the first writing system I by 180 ° around the polygon mirror 4. The laser light emitted from the light source 1-2 is converted into parallel light by the collimator lens 2-2, then enters the polygon mirror 4 through the cylindrical lens 3-2, is changed and scanned by the polygon mirror 4, and is first scanned. , Reflected by the second Fθ lenses 5-2 and 6-2 and the third mirror 9-2, guided to the direction of the photosensitive drum 10, and from the center of a predetermined scanning position on the photosensitive drum 10. Scanning is performed toward the end in the direction opposite to that of the one writing system I. In the figure, 11-1, 11-2 first, second writing system I, respectively, in synchronization detection unit II, each of the synchronization detection unit 11-1 and 11-2 detects the scanning timing of the laser beam . Further, the scanning timing of the laser beams of the first and second writing systems I and II and the writing start position are synchronized according to the timing detected by the synchronization detection units 11-1 and 11-2 by a writing control circuit (not shown). It is configured as follows. As described above, in the optical scanning device of FIG. 3, a single deflecting device uses a plurality of general-purpose small lenses to connect the scanning lines to form a low-cost and compact wide optical system. Therefore, considerable space saving can be achieved with respect to the method of constructing the wide optical system.

  However, regarding the housing that houses the optical scanning device configured as described above, the size of the housing needs to be about 914 mm when the A0 machine is configured using two A2 lenses. Therefore, as shown in FIG. 4 which shows the shape of the housing, the housing 21 is required to have a minimum width of 970 mm, a depth of 450 mm, and a height of 150 mm, and the size of the housing is insignificant compared to a general A3 machine or the like. There is a drawback that becomes larger. Therefore, in addition to the part cost, the mold cost becomes enormous and the cost increases. Reference numeral 22 denotes a positioning pin, and 23 denotes an eccentric cam for position adjustment. The eccentric cam 23 is rotated to adjust the optimum position of the housing 21.

On the other hand, dividing the housing into a plurality of units is disclosed in Patent Document 4, for example. In Patent Document 4, a plurality of housings are divided in a direction perpendicular to the optical center, and these housings are coupled following a guide member positioned in a direction perpendicular to the photosensitive drum.
JP-A-11-95152 JP 2000-18171 A JP 2001-341348 A JP 4-110912 A

  However, in the invention described in Patent Document 4, there is a single writing optical system. When the housings are divided in this way, the mold for making each housing becomes small, but it is divided depending on the size of the supporting component. The size of the housing is different, and various sizes of housings must be made. Accordingly, it is necessary to prepare various types of molds, resulting in an increase in manufacturing cost. Further, when applied to a plurality of writing optical systems, it takes time to adjust the connection, and the advantage of reducing the mold is offset in terms of manufacturing cost.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the number of parts by sharing a housing when dividing a housing that accommodates an optical scanning device.

In order to achieve the above object, the first means mainly arranges a plurality of writing optical systems in point symmetry with respect to the rotation center of one deflecting device, and scans the light beam of the writing optical system with the deflecting device. An optical element holding member that holds an optical element that performs wide optical writing by being connected in the scanning direction. The optical element holding member is connected to a central unit that holds the deflection device and to both sides of the central unit. The left and right units each independently holding the first and second writing optical systems, and the central unit is made of a material having higher thermal conductivity than the left and right units, and the connection characterized in that it is composed one housing by three units, which are.

The second means is characterized in that in the first means, the central unit and the left and right units are connected to each other by a positioning member.

The third means is characterized in that, in the second means, the positioning member is attached to the central unit and the left and right units via an elastic member.

Scanning operation according to a fourth means apparatus, the first and second writing optical system includes an optical element holding member according to the first to third means, the deflection device disposed on the optical element holding member And optical scanning means for performing wide writing by connecting the first and second writing optical systems.

The fifth means includes an optical scanning device according to the fourth means and an image forming means for outputting an image written on the image carrier by the optical scanning device as a visible image on a recording medium. Features.
In the embodiment described later , the deflecting device is the polygon mirror 4, the first and second writing optical systems are the first and second writing optical systems I and II, the two units are the housing units 31a and 31b, and the central unit. The unit corresponds to the central unit 51, the left and right units correspond to the left unit 61 and the right unit 62, the positioning members correspond to the sheet metals 71 and 81, and the elastic members correspond to the rubber sheets 72 and 82, respectively.

  According to the present invention, a housing in which a plurality of writing optical systems are mounted can be formed with a small mold without producing a large mold, and the mold can be miniaturized. It is possible to reduce the environmental load such as expenses.

  Hereinafter, the best mode for carrying out the present invention will be described. As the optical scanning device used here, the above-described optical scanning device of FIG. 3 is used. In addition, the same reference number is attached | subjected to the component substantially the same as the prior art mentioned above, and the overlapping description is abbreviate | omitted.

FIG. 1 is a perspective view schematically showing a first embodiment of the present invention. In the first embodiment, as shown in FIG. 3, the light source 1-1 of the first writing system I, the collimating lens 2-1, the cylindrical lens 3-1, the first and second Fθ lenses 5- 1, 6-1, first, second and third mirrors 7-1, 8-1 and 9-1, a light source 1-2 of the second writing system II, a collimating lens 2-2, a cylindrical lens 3- 2, first and second Fθ lens 5-2 and 6-2, first, the optical elements such as the second and third mirrors 7-2,8-2,9-2 is a port Rigonmira 4 Focusing on the point symmetrically arranged with respect to the center, using this feature, the housing is divided into left and right with the polygon mirror 4 as the center, and the two housing units 31a and 31b having the same shape are connected. So that it becomes one housing 31 . Thus, since the left and right housing units 31a and 31b are formed of common parts, the size of the mold can be halved, and the mold investment can be greatly reduced.

  FIG. 2 is an exploded perspective view showing only the housing in the second embodiment of the present invention. In the second embodiment, the housing has a three-part configuration including a central unit 51 that is a portion on which a motor (not shown) of the polygon mirror 4 that is a heating element is mounted, and left and right units 61 and 62. Yes.

  The central unit 51 includes a bottom plate portion 52, a front side plate portion 53 and a rear side plate portion 54 formed so as to be orthogonal to both ends thereof, and ribs for reinforcing the four corner intersections of the bottom plate portion 52 and the side plate portion 53. 55 is integrally formed. An opening 56 for the polygon mirror 4 is perforated at substantially the center of the bottom plate portion 52. The central unit 51 is made of a material such as AL having a high thermal conductivity in order to efficiently release the heat generated from the polygon motor to the outside. Further, the central unit 51 protrudes to the outer wall of the housing and can efficiently release heat to the outside.

  The left and right units 61 and 62 include bottom plate portions 63a and 63b, front side plate portions 64a and 64b located on the front side of these bottom plate portions 63a and 63b, and rear side plate portions 65a located on the rear side of the bottom plate portions 63a and 63b, respectively. , 65b and side plate portions 66a, 66b located on the side surfaces of the bottom plate portions 63a, 63b are integrally formed, have a substantially point-symmetric shape around the polygon mirror 4, and are formed with the same mold. ing. Although a partial difference in shape is not shown, it is handled by nesting or the like. The materials of the left and right units 61 and 62 are molded in a mold such as Mo for cost reduction.

  Reference pins 67a for positioning in the YZ direction with respect to the central unit 51 are provided on the edge of the bottom plate part 63a, 63b of the left and right units 61, 62, which is the other side of the bottom plate part 52 of the central unit 51. 67b protrudes substantially horizontally, and receiving holes 68a into which the reference pins 67a and 67b are inserted at corresponding positions on both side edges of the bottom plate portion 52 of the central unit 51 (not shown in FIG. 2 and thus omitted). ) Is provided. In addition, in order to obtain position accuracy in the Y direction by abutting the central unit 51 and the left and right units 61 and 62, reference pins 69a and 69b are provided at two upper and lower positions on the edge portions of the side plate portions 53 of the central unit 51, respectively. (It is omitted because it is not visible in FIG. 2) protrudes substantially horizontally, and at the corresponding positions of the side edge portions of the front side plate portions 64 a and 64 b and the rear side plate portions 65 a and 65 b of the left and right units 61 and 62. Are provided with receiving holes 70a (not shown in FIG. 2 and omitted) 70b into which the reference pins 69a and 69b are inserted. These reference pins 69a and 69b also ensure the positional accuracy of the left and right units 61 and 62 in the rotational directions of γ and α.

  In order to connect the central unit 52 and the left and right units 61 and 62 with high precision, an iron sheet metal 71 is attached to the rubber sheet 72 on the rear side plate portion 54 of the central unit 52 and the rear side plate portions 65a and 65b of the left and right units 61 and 62. Is attached through. The rear side plate portions 54, 65a, 65b are omitted from the reference pins (not shown in FIG. 2 because they are not visible in FIG. 2) at the same positions as the reference pins 73, 74a, 74b provided on the front side plate portions 53, 64a, 64b. ) Are provided so as to protrude substantially horizontally, and receiving holes 75, 76a, 76b into which these reference pins are inserted are provided. With these reference pins 74, 75a, 75b, the sheet metal 71 accurately connects the central unit 52 and the left and right units 61, 62, and ensures the strength of the entire outer frame while positioning the entire Y direction during connection. Do. Further, the rubber sheet 72 is prevented from being distorted in the X direction as the temperature rises due to the difference in linear expansion coefficient due to the material difference between the sheet metal 71 and the central unit 52. A hole for inserting the reference pins 74, 75 a, 75 b may be formed in the rubber sheet 72. Such sheet metal 71 and rubber sheet 72 are also provided on the front side plate portions 53, 64a, 64b side.

  A sheet metal 81 similar to the sheet metal 71 is also fixed to the side plate part 66 a by screwing or the like at both ends of the sheet metal 71. The metal plates 71 and 81 ensure the strength of the outer frame and the accuracy during connection. The sheet metal 81 is also screwed directly to the side surface side plate portion 66 via a rubber sheet 82 similar to the rubber sheet 72. The rubber sheet 72 is prevented from being distorted in the Y direction as the temperature rises due to the difference in coefficient of linear expansion caused by the material difference between the sheet metal 71 and the left and right units 61 and 62.

  As described above, in the second embodiment, one central unit 52 and two left and right units 61 and 62 are formed, and the left and right units 61 and 62 are substantially point-symmetric with respect to the polygon mirror 4. As a result, they can be made with the same mold, and miniaturization and mold sharing can be performed at the same time to reduce costs. Further, the central unit 52 is made of a material having good heat dissipation, so that the polygon motor can efficiently dissipate heat, and is fastened between each unit and a connecting member via an elastic member such as a rubber sheet. Therefore, if the housing is prevented from being distorted due to a difference in linear expansion coefficient due to a difference in material, and used in an image forming apparatus, a stable image can always be obtained.

  FIG. 5 is a schematic configuration diagram showing the overall configuration of a digital copying machine using the above-described optical scanning device. This digital copying machine can be roughly divided into a copying machine main body 500 and an image reading unit 600. The copying machine main body 500 controls the optical scanning device 501, cassettes 502 and 502 ′ for storing sheets, sheet feed rollers 503 and 503 ′ for taking out sheets one by one from the cassettes 502 and 502 ′, and conveyance timing. A registration roller 504, a transfer charger 505, a process cartridge 509 in which the photosensitive drum 10, the developing roller 507, the charging roller 508, and the like are integrated, a fixing roller 510 incorporating a halogen heater, a pressure roller 511, , A conveyance roller 512 and a paper discharge roller 513 are included. The image reading unit 600 forms an image on the original reading unit 601 fixed on the original table on the photoelectric conversion element 603 such as a CCD via the imaging lens 602, moves the mirror group 604, sequentially Convert to data. In the digital copying machine having such a configuration, first, the semiconductor laser is modulated in accordance with the image signal by the optical scanning device 501, and a latent image is formed on the photosensitive drum 10 uniformly charged by the charging roller 508, The toner is visualized by toner supplied from the developing roller 507. On the other hand, the paper taken out by the paper feed roller 503 or 503 'is conveyed by the registration roller 504 in accordance with the image writing timing of the optical scanning device 501, and the toner image is transferred. The transferred image is fixed by the fixing roller 510 and discharged.

1 is a perspective view schematically showing a first embodiment of the present invention. It is a perspective view which decomposes | disassembles and shows only the housing in the 2nd Embodiment of this invention. It is a schematic block diagram which shows an example of an optical scanning scanning apparatus. It is a schematic perspective view which shows the housing which accommodates the optical scanning device of FIG. 1 is a schematic configuration diagram showing an overall configuration of a digital copying machine using the above-described optical scanning device.

Explanation of symbols

500 Copier Main Body 501 Optical Scanning Device 509 Process Cartridge 510 Fixing Roller 600 Image Reading Unit 601 Reading Unit 603 Photoelectric Conversion Element 1-1, 1-2 Light Source 2-1, 2-2 Collimating Lens 3-1, 3-2 Cylindrical Lens 4 Polygon mirror 5-1 and 5-2 First Fθ lens 6-1 and 6-2 Second Fθ lens 7-1 and 7-2 First mirror 8-1 and 8-2 Second mirror 9-1, 9-2 Third mirror 10 Photosensitive drum 31 Housing 31a, 31b Housing unit 51 Central unit 53, 64a, 64b Front side plate portion 54, 65a, 65b Rear side plate portion 52, 63a, 63b Bottom plate portion 61 Left Unit 62 Right unit 67a, 67b, 69a Reference pin 68a, 70b, 75, 76a, 76b 71 81 sheet metal 72, 82 rubber sheet I first writing system
II Second writing system

Claims (5)

An optical system in which a plurality of writing optical systems are arranged point-symmetrically with respect to the rotation center of one deflecting device, and a light beam of the writing optical system is scanned by the deflecting device and connected in the main scanning direction to perform wide-width optical writing. In the optical element holding member that holds the element,
The optical element holding member is connected to a central unit that holds the deflecting device and left and right units that are connected to both sides of the central unit and hold the first and second writing optical systems independently. Consists of two units
The central unit is made of a material with higher thermal conductivity than the left and right units,
An optical element holding member, wherein one housing is constituted by the three connected units . 2. The optical element holding member according to claim 1, wherein the central unit and the left and right units are connected to each other by a positioning member. 3. The optical element holding member according to claim 2, wherein the positioning member is attached to the central unit and the left and right units via an elastic member. The optical element holding member according to any one of claims 1 to 3,
A first and a second writing optical system including the deflecting device disposed on the optical element holding member;
Optical scanning means for performing wide writing by connecting the first and second writing optical systems;
Optical scanning apparatus which is characterized in that it comprises. An optical scanning device according to claim 4,
Image forming means for outputting an image written on the image carrier by the optical scanning device as a visible image on a recording medium;
An image forming apparatus characterized by comprising a.

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