JP2006201284A - Optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner and an image forming apparatus in which the heat generated in a light deflector is hardly conducted to an optical housing and other optical elements without complicating the configuration of the light deflector. <P>SOLUTION: The light deflector 120 is composed so that the light deflector is made contact directly with a base plate 123 of the light deflector only at base plate fixing parts 124 of the optical housing 110, and the light deflector 120 and the optical housing 110 are not made in direct contact with each other at other parts. With this composition, the heat is conducted only from the base plate fixing parts 124 to the optical housing 110 and the heat quantity conducted to the optical housing 110 is reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device and an image forming apparatus.

  In an electrostatic copying type image forming apparatus such as a digital copying machine or a laser printer, a light beam from a laser light source is deflected / scanned by an optical deflector, and the laser light is irradiated onto a uniformly charged photoreceptor. This forms an electrostatic latent image on the photoreceptor. The electrostatic latent image is developed with toner to form a toner image, and the toner image is transferred to an output sheet to output an image.

  The configuration of the optical scanning device is shown in FIG. The optical scanning device 200 includes a laser light source 201, a coupling lens 202, an aperture 203, an optical deflector 220, an fθ lens 204, a toroidal lens 205, a folding mirror 206, a synchronization mirror 207, and a synchronization detection sensor. 208 is configured to be provided on the optical housing 210.

  The laser light source 201 outputs laser light based on the input image signal. The output laser light is applied to the optical deflector 220 through the coupling lens 202 and the aperture 203. The optical deflector 220 deflects / scans the laser light. The deflected / scanned laser light is irradiated onto the photosensitive member via the fθ lens 204, the toroidal lens 205, and the folding mirror 206, whereby an electrostatic latent image is formed on the photosensitive member. The end light of the laser beam reflected by the synchronization mirror 207 is detected by the synchronization detection sensor 208 and used to synchronize the scanning lines.

  As the optical deflector 220, a polygon mirror (rotating polygonal mirror) is generally used. The polygon mirror is a mirror provided with a polygonal mirror surface in a direction parallel to the rotation axis, whereby the laser light is deflected / scanned from the laser light source.

  The configuration of a conventional optical deflector 220 is shown in FIG. The optical deflector 220 includes a polygon mirror 221, a polygon motor 222, and a base plate 223. The optical deflector 220 is configured to be provided on the optical housing 210.

  The polygon motor 222 and the polygon mirror 221 fixed to the rotation shaft of the polygon motor 222 are provided on the base plate 223. Further, the bearing portion 225 of the polygon motor 222 protrudes on the back side of the base plate 223. The base plate 223 is supported by a base plate fastening portion 224 of the optical housing 210 and is fixed by a fixing member 226 such as a screw.

  As shown in FIG. 11, the conventional optical deflector 220 has a structure in which the bearing 225 of the polygon motor 222 is in direct contact with the optical housing 210 and heat generated when the polygon motor 222 is driven is easily transmitted to the optical housing. It has become.

  Heat generated by driving the polygon motor 222 is transmitted to the optical elements (laser light source 201, coupling lens 202, fθ lens 204, etc.) in the optical scanning device 200 via the optical housing 210, and the optical characteristics of each optical element. Adversely affects the image forming position and causes a defective operation such as a deviation in focus (focus shift), a beam spot diameter increase, and a writing magnification error. If these defective operations occur, the apparatus cannot perform the intended optical scanning, and good image formation cannot be expected.

  In particular, in recent years, the polygon mirror drive speed has been increasing in order to increase the image output speed. Therefore, the amount of heat generated when the polygon motor is driven at a high speed has increased. Therefore, it is considered how to avoid heat transfer to the optical element as described above.

  In Patent Document 1, the optical deflector is held in an optical housing via a holding member, and the optical housing is formed of a material having a lower thermal conductivity than that of the holding member, so that heat generated from the optical deflector can be reduced to other optical components. An optical scanning device that makes it difficult to transmit to an element has been proposed.

  Further, in Patent Document 2, a heat transfer member for forming the vicinity of the optical deflector as a substantially sealed space using a cover member or a seal member made of iron plate and transmitting heat generated by the optical deflector to the cover member. Has been proposed in such a manner that the heat generated from the optical deflector is dissipated from the cover member and hardly transmitted to other optical elements.

In Patent Document 3, the optical deflector is not fixed to the optical housing, but is fixed to other parts of the image forming apparatus so that the optical deflector and the optical housing are not in direct contact with each other. There has been proposed an optical scanning device that makes it difficult to transfer heat generated from a deflector to an optical housing and other optical elements.
JP 2001-154134 A JP 2001-208997 A JP 2002-062500 A

  However, the above-described invention has the following problems.

  In the optical scanning devices described in Patent Literature 1 and Patent Literature 2, the configuration of the optical scanning device is complicated. In addition, the polygon motor, which is a heat generating part of the optical deflector, and the optical housing are configured to contact indirectly through a holding member or a heat transfer member, but heat is applied to the optical housing through the holding member or the heat transfer member. There is a problem that is transmitted.

  Further, in the optical scanning device described in Patent Document 3, since it is necessary to fix the optical deflector to other components of the image forming apparatus, the conditions and the shape when using the technology are limited. Further, since the optical deflector is fixed using other parts of the image forming apparatus, there is a problem that the configuration of the optical scanning device becomes complicated.

  The present invention has been proposed in view of the above problems, and does not complicate the configuration of the optical deflector and makes it difficult to transfer heat generated from the optical deflector to the optical housing and other optical elements. An object is to provide an image forming apparatus and an image forming apparatus.

  The invention according to claim 1 includes a laser light source, an optical deflector that deflects and scans laser light output from the laser light source, and an optical housing that houses the laser light source and the optical deflector. The optical deflector includes a base plate serving as a base of the optical deflector, a deflection mirror having a plurality of deflection surfaces, a motor that rotationally drives the deflection mirror, and a bearing that casings a rotation shaft of the motor. The optical housing has an optical deflector support that supports the optical deflector, and only a part of the base plate of the optical deflector is supported by the optical deflector support. In the optical scanning device, the deflection mirror, the motor, and the bearing portion do not contact the optical housing.

  According to a second aspect of the present invention, in the first aspect of the invention, the optical scanning device includes a plurality of the laser light sources, and the laser light output from the plurality of laser light sources is used as a single optical deflector. It is characterized by performing deflection scanning.

  According to a third aspect of the invention, in the first or second aspect of the invention, the optical housing is made of a resin material.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the vicinity of the periphery of the optical deflector is surrounded by a glass material.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the optical scanning device further includes a control unit that controls the motor of the optical deflector. The portion is disposed outside the optical housing and at a location that does not contact the optical housing.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the optical scanning device further outputs the laser beam deflected and scanned by the optical deflector to the outside of the optical scanning device. The optical system includes an fθ optical system that guides light to a photoconductor provided on the substrate, and the fθ optical system is made of a resin material.

  A seventh aspect of the invention is an image forming apparatus comprising the optical scanning device according to any one of the first to sixth aspects.

  According to the present invention, it is possible to make it difficult for heat generated from the optical deflector of the optical scanning device to be transmitted to the optical housing and other optical elements, and thus it is possible to suppress deterioration of the optical characteristics of the optical element due to heat. Become. As a result, the optical characteristics can be maintained at a high level, so that good optical scanning can be performed.

  The optical scanning device of the first embodiment will be described with reference to FIG. FIG. 1 shows the configuration of the optical scanning device of this embodiment.

  The optical scanning device 100 includes a laser light source 101, a coupling lens 102, an aperture 103, an optical deflector 120, an fθ lens 104, a toroidal lens 105, a folding mirror 106, a synchronous mirror 107, and a synchronous detection sensor. 108 is configured to be provided on the optical housing 110.

  The laser light source 101 outputs laser light based on the input image signal. The output laser light is applied to the optical deflector 120 through the coupling lens 102 and the aperture 103. The optical deflector 120 deflects / scans the laser light. The deflected / scanned laser beam is applied to the folding mirror 106 via the fθ lens 104 as the first imaging lens and the toroidal lens 105 as the second imaging lens. The irradiated laser beam is reflected from the laser beam exit window of the optical housing onto the photosensitive member by the folding mirror 106, whereby an electrostatic latent image is formed on the photosensitive member. Further, the edge light of the laser beam reflected by the synchronization mirror 107 is detected by the synchronization detection sensor 108 and used to synchronize the scanning lines.

  Next, the optical deflector 120 of the optical scanning device 100 of this embodiment will be described with reference to FIG. FIG. 2 shows the configuration of the optical deflector 120.

  The optical deflector 120 includes a polygon mirror 121, a polygon motor 122, and a base plate 123. The optical deflector 120 is configured to be provided on the optical housing 110.

  The polygon motor 122 and the polygon mirror 121 fixed to the rotation shaft of the polygon motor 122 are provided on the base plate 123. Further, the bearing portion 125 of the polygon motor 122 protrudes toward the back side of the base plate 123. The base plate 123 is supported by the base plate fastening portion 124 of the optical housing 110 and is fixed by a fixing member 126 such as a screw.

  As shown in FIG. 2, the optical deflector 120 of this embodiment is in direct contact with the base plate 123 of the optical deflector 120 only at the base plate fastening portion 124 of the optical housing 110, and the optical deflector 120 and the optical housing at other locations. 110 is configured not to contact directly. With this configuration, the polygon motor 122 and the bearing portion 125 that are likely to become high temperature do not directly contact the optical housing 110, and the generated heat is transmitted to the optical housing 110 only from the base plate fastening portion 124. Therefore, the optical scanning device 100 according to the present embodiment reduces the amount of heat transmitted to the optical housing 110, makes it difficult to transmit heat to other optical elements such as the laser light source 101 and the fθ lens 104, and improves optical characteristics. Since the level can be maintained, good optical scanning can be performed.

  The optical deflector 120 of the present embodiment is not limited to the configuration shown in FIG. 2, and the base plate 123 is in direct contact only with the base plate fastening portion 124 of the optical housing 110, and the optical deflector is used in other places. A configuration as shown in FIG. 3 may be used as long as 120 and the optical housing 110 are not in direct contact with each other.

  In the optical scanning device 100 of the present embodiment, the optical housing 110 and the base plate fastening portion 124 are preferably made of a resin material. The optical housing 110 made of a resin material has a lower thermal conductivity than an optical housing made of a metal such as aluminum. Therefore, by configuring the optical housing 110 and the base plate fastening portion 124 with a resin material, it is possible to make it difficult for heat to be transmitted to other optical elements via the optical housing 110.

  As shown in FIG. 4, in the optical scanning device 100 of the present embodiment, it is preferable that the optical deflector 120 is surrounded by a material such as glass. By configuring in this way, the optical deflector 120 and other optical elements are spatially separated, and the thermal conductivity in the space is lowered, so that the heat generated from the optical deflector 120 is transmitted to the other through the air. It is possible to suppress transmission to the optical element. As a material surrounding the optical deflector 120, a member conventionally used in the optical scanning device 100 such as the sound insulating glass 130 is used, so that the configuration of the device is not complicated.

  In the optical scanning device 100 of this embodiment, it is preferable to use an optical element made of a resin material as an optical element such as the fθ lens 104. With this configuration, the optical scanning device 100 can be provided at low cost. In general, an optical element made of a resin material has a demerit that it easily causes volume fluctuation and magnification fluctuation due to heat compared to an optical element made of glass or the like. However, in the optical scanning device 100 of the present embodiment, the amount of heat transmitted to the optical element is reduced. Since this can be reduced, this disadvantage can be avoided.

  The polygon mirror 121 of the optical deflector 120 is driven by a polygon motor 122, which is controlled by a driver IC 141 on the control board 140. The driver IC 141 is a semiconductor circuit that controls the rotation speed by applying a pulse to the polygon motor 122. The driver IC 141 generates heat, and particularly when the rotation speed of the polygon motor 122 (polygon mirror 121) increases, the driver IC 141 generates heat. The amount will increase.

  Therefore, as shown in FIG. 5, the control board 140 including the driver IC 141 is preferably disposed outside the optical scanning device 100 at a location that does not have a thermal effect on the optical scanning device 100. For example, the control board 140 and the optical deflector 120 are connected by wiring, and are installed adjacent to the location where the optical scanning device 100 is installed in the image forming apparatus. With this configuration, the control board 140 that generates heat is disposed outside the optical scanning device 100, so that the amount of heat transmitted to the optical housing 110 can be reduced.

  Next, an optical scanning device according to a second embodiment will be described with reference to FIGS. FIG. 6 is a top view of the optical scanning device of the present embodiment, and FIG. 7 is a cross-sectional view of the optical scanning device of the present embodiment. FIG. 8 is an enlarged view of a portion surrounded by a dotted line in FIG. The optical scanning device according to the present embodiment corresponds to a tandem image forming apparatus that forms a color image by superimposing a plurality of color toner images.

  The optical scanning device 100 of this embodiment includes four laser light sources 101 (a to d), a coupling lens 102 provided for each laser light source, an aperture 103, an optical deflector 120, an fθ lens 104, and a return. The mirror 106 is configured to be provided on the optical housing 110. The optical deflector 120 includes a polygon mirror 121, a polygon motor 122, and a base plate 123.

  The polygon motor 122 and the two polygon mirrors 121 fixed to the rotation shaft of the polygon motor 122 are provided on the base plate 123. Further, the bearing portion 125 of the polygon motor 122 protrudes toward the back side of the base plate 123. The base plate 123 is supported by the base plate fastening portion 124 of the optical housing 110 and is fixed by a fixing member 126 such as a screw.

  The four laser light sources 101 (a to d) output laser light based on the input image signals. The output laser light is applied to the optical deflector 120 through the coupling lens 102 and the aperture 103. The optical deflector 120 performs deflection / scanning by distributing the laser light from the laser light source 101 in two symmetrical directions. The laser light deflected / scanned in two directions by two beams by the optical deflector 101 passes through the fθ lens 104 (a, b) having an upper and lower two-layer structure, and a folding mirror 106 (a) provided for each laser light. ˜d) and passes through the laser light exit window 150 of the optical housing 110. Each laser beam that has passed through the laser beam exit window 150 forms an electrostatic latent image on each photoconductor 305 via the toroidal lens 105 and the reflection mirror 151. This electrostatic latent image is developed by the developing device 304 for each color toner (C, M, Y, K), and a color image is formed by superimposing and transferring this.

  As shown in FIG. 8, the optical deflector 120 of this embodiment is in direct contact with the base plate 123 of the optical deflector 120 only at the base plate fastening portion 124 of the optical housing 110, and the optical deflector 120 and the optical housing at other locations. 110 is configured not to contact directly. With this configuration, the polygon motor 122 and the bearing portion 125 that are likely to become high temperature do not directly contact the optical housing 110, and the generated heat is transmitted to the optical housing 110 only from the base plate fastening portion 124. Therefore, the optical scanning device 100 according to the present embodiment reduces the amount of heat transmitted to the optical housing 110, makes it difficult to transmit heat to other optical elements such as the laser light source 101 and the fθ lens 104, and provides good optical scanning. Can be performed.

  In the optical scanning device 100 of the present embodiment, the optical housing 110 and the base plate fastening portion 124 are preferably made of a resin material. The optical housing 110 made of a resin material has a lower thermal conductivity than an optical housing made of a metal such as aluminum. Therefore, by configuring the optical housing 110 and the base plate fastening portion 124 with a resin material, it is possible to make it difficult for heat to be transmitted to other optical elements via the optical housing 110.

  Further, in the optical scanning device 100 of the present embodiment, it is preferable that the optical deflector 120 is surrounded by a material such as glass. By configuring in this way, the optical deflector 120 and other optical elements are spatially separated, and the thermal conductivity in the space is lowered, so that the heat generated from the optical deflector 120 is transmitted to the other through the air. It is possible to suppress transmission to the optical element. As a material surrounding the optical deflector 120, a member conventionally used in the optical scanning device 100 such as sound insulation glass is used, so that the configuration of the device is not complicated.

  In the optical scanning device 100 of this embodiment, it is preferable to use an optical element made of a resin material as an optical element such as the fθ lens 104. With this configuration, the optical scanning device 100 can be provided at low cost. In general, an optical element made of a resin material has a demerit that it easily causes volume fluctuation and magnification fluctuation due to heat compared to an optical element made of glass or the like. However, in the optical scanning device 100 of the present embodiment, the amount of heat transmitted to the optical element is reduced. Since this can be reduced, this disadvantage can be avoided.

  Further, it is preferable that the control board including the driver IC for controlling the driving of the polygon motor 122 is arranged outside the optical scanning apparatus 100 so as not to have a thermal effect on the optical scanning apparatus 100. With this configuration, since the control board that generates heat is disposed outside the optical scanning device 100, the amount of heat transmitted to the optical housing 110 can be reduced.

  Next, a third embodiment will be described with reference to FIG. FIG. 9 shows the configuration of the image forming apparatus of this embodiment. The image forming apparatus 300 includes a document table 301, a reading device 302, an optical scanning device (writing device) 303, a developing device 304, a photosensitive member 305, a fixing device 306, a paper discharge roller 307, and a paper discharge tray. 308, a paper feed tray 309, and a paper feed roller 310.

  The reading device 302 reads the image data of the document placed on the document table 301 and transmits the read image data to the optical scanning device 303 as an image signal. The optical scanning device 303 irradiates a writing laser based on the image signal to form an electrostatic latent image on the photoconductor 305. The developing device 304 develops the electrostatic latent image on the photoconductor 305 to form a toner image. The toner image is transferred onto a sheet conveyed from the sheet feeding tray 309 by the sheet feeding roller 310. The fixing device 306 thermally fixes the toner image transferred onto the paper. The sheet on which the toner image is thermally fixed is discharged onto a discharge tray 308 via a discharge roller 307.

  The image forming apparatus 300 of this embodiment includes the optical scanning device described in the first embodiment and the second embodiment as the optical scanning device 303. According to the present embodiment, in the optical scanning device, it is possible to suppress a decrease in the optical characteristics of the optical element due to heat generated from the optical deflector and maintain the optical characteristics at a high level, so that a good optical scanning can be performed. It becomes possible for the image forming apparatus 300 to form an image with an originally intended image quality.

It is a figure which shows the structure of the optical scanning device of this embodiment. It is a figure which shows the structure of the optical deflector of this embodiment. It is a figure which shows the structure of the optical deflector of this embodiment. It is a figure which shows the optical scanning device which surrounded the optical deflector with the sound insulation glass. It is the figure which installed the control board outside the optical scanning device. It is a top view of an optical scanning device having a plurality of light sources. It is sectional drawing of the optical scanning device with a some light source. It is the figure which expanded a part of FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. It is a figure which shows the structure of the conventional optical scanning device. It is a figure which shows the structure of the conventional optical deflector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical scanning device 104 f (theta) lens 110 Optical housing 120 Optical deflector 121 Polygon mirror 122 Polygon motor 123 Base plate 124 Base plate fastening part 125 Bearing part 130 Sound insulation glass 140 Motor control board 141 Driver IC
300 Image forming apparatus 305 Photoconductor

Claims (7)

An optical scanning device comprising: a laser light source; an optical deflector that deflects and scans laser light output from the laser light source; and an optical housing that houses the laser light source and the optical deflector.
The optical deflector is
A base plate as a base of the optical deflector;
A deflection mirror having a plurality of deflection surfaces;
A motor for rotationally driving the deflection mirror;
A bearing portion for casing the rotating shaft of the motor,
The optical housing has an optical deflector support that supports the optical deflector,
Only a part of the base plate of the optical deflector is supported by the optical deflector support,
The optical scanning device, wherein the deflection mirror, the motor, and the bearing portion do not contact the optical housing. The optical scanning device includes a plurality of the laser light sources,
The optical scanning apparatus according to claim 1, wherein the laser light output from the plurality of laser light sources is deflected and scanned by one optical deflector.   The optical scanning device according to claim 1, wherein the optical housing is made of a resin material.   4. The optical scanning device according to claim 1, wherein the vicinity of the periphery of the optical deflector is surrounded by a glass material. 5. The optical scanning device further includes a control unit that controls the motor of the optical deflector,
5. The optical scanning device according to claim 1, wherein the control unit is disposed outside the optical housing and at a location that does not contact the optical housing. 6. The optical scanning device further includes an fθ optical system that guides the laser beam deflected and scanned by the optical deflector to a photoconductor provided outside the optical scanning device,
The optical scanning apparatus according to claim 1, wherein the fθ optical system is made of a resin material.   An image forming apparatus comprising the optical scanning device according to claim 1.

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