JP2010128359A - Optical scanner, image forming apparatus equipped with the optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner which saves space, has a small number of components, reduces cost, and prevents an abnormal image from being generated due to flare light. <P>SOLUTION: A luminous flux L from a light source 201 is a divergent light beam and is converged into a substantially parallel light beam passing through a coupling lens 202, however a portion of the luminous flux L which largely diverges beyond the diameter of a coupling lens 202 is not shielded, reflected on an optical element and becomes stray light. The unshielded luminous flux L which is repeatedly reflected and reaches a latent image carrier may generate an abnormal image. Therefore, the divergent light from the light source 201 is shielded by a wall in the vicinity of an aperture 203 integrally provided in an optical housing 200. There is no luminous flux L not passing through the aperture 203 and the abnormal image due to the flare light is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention uses an optical scanning device used in an image forming apparatus such as a digital PPC having a writing unit that deflects a beam emitted from a light source by a deflector and performs exposure on a photosensitive member by an imaging optical system, and the same. The present invention relates to an image forming apparatus.

  Some image forming apparatuses such as copiers, printers, and facsimiles irradiate a scanning light according to image information on the latent image carrier by deflecting scanning to form a latent image on the latent image carrier. It is known that the latent image is developed to obtain an image. An optical scanning device that deflects and scans writing light generally includes a coupling lens that converts a light beam from a light source unit into a substantially parallel light, an aperture that shapes parallel light from the coupling lens, and a cylindrical image that converts the shaped light beam into a line image. A lens, a polygon scanner that deflects and scans the light beam, and an optical component such as an imaging lens that forms an image of the writing light deflected and scanned by the polygon scanner on the surface of the latent image carrier are provided. Further, synchronization detection means for obtaining a synchronization signal for determining the writing light writing position is provided, and these are housed in an optical housing.

  The optical scanning device as described above has various requirements such as high quality images, high speed, space saving, energy saving, and low cost, and various devices have been conventionally made.

JP 2007-178744 A JP 2007-240884 A

  In Patent Document 1, an aperture integrated with an optical housing is disclosed, and cost reduction and improvement in assembly are achieved by reducing the number of parts. On the other hand, the light source unit is separate from the optical housing. It is conceivable that the number of components increases and the cost reduction effect is reduced. Further, since the light source unit is configured, the degree of freedom in layout is small, and the unit size is limited.

  Patent Document 2 discloses a configuration in which a light source is directly attached to an optical housing, and the optical housing and the aperture are integrated. The component configuration is simplified, and the cost is reduced and the assembly is reduced by reducing the number of components. The improvement of the property is aimed at. However, of the light flux from the light source, the light passing outside the coupling lens is reflected by the optical element and may reach the latent image carrier and become an abnormal image.

  Therefore, the present invention proposes a high-quality optical scanning device that can be manufactured at low cost with a small space and has few components, and an image forming apparatus using the optical scanning device that uses the flare light.

  The optical scanning device according to the first aspect of the present invention includes at least a light source, a coupling lens for coupling a light beam emitted from the light source, and shaping the light beam from the light source into a desired shape. An optical scanning device comprising: an aperture unit that performs scanning; a deflector that scans a light beam from the light source; an optical element that forms an image of the light beam deflected by the deflector into a desired shape; and an optical housing including the optical element. A wall around an aperture provided in the optical housing shields a light beam outside the coupling lens out of the light beam emitted from the light source.

  According to a second aspect of the present invention, in the optical scanning device of the first aspect, the aperture portion is formed integrally with the optical housing.

  According to a third aspect of the present invention, in the optical scanning device according to the first or second aspect, the wall of the portion where the aperture portion is provided surrounds the coupling lens.

  According to a fourth aspect of the present invention, in the optical scanning device according to the first or second aspect, the wall of the portion provided with the aperture portion surrounds the emission portion of the light source.

  According to a fifth aspect of the present invention, in the optical scanning device according to the first or second aspect, a light shielding plate is attached to an upper portion of a wall around the aperture portion.

  According to a sixth aspect of the present invention, in the optical scanning device according to the fifth aspect, a wall around the aperture portion surrounds the coupling lens.

  According to a seventh aspect of the present invention, in the optical scanning device according to the fifth aspect, a wall around the aperture portion surrounds the emission portion of the light source.

  According to an eighth aspect of the present invention, in the optical scanning device of the first aspect, the aperture portion is a separate member from the optical housing, a wall around the aperture portion is surrounded by the coupling lens, and a light-shielding portion is provided above the wall. A plate is attached.

  According to a ninth aspect of the present invention, in the optical scanning device of the first aspect, the aperture portion is a separate member from the optical housing, a wall around the aperture portion surrounds the light emitting portion of the light source, and a light-shielding portion is provided above the wall. It is characterized by being attached with a plate.

  According to a tenth aspect of the present invention, in the optical scanning device according to the eighth or ninth aspect, the aperture section and the plate are formed of the same component.

  An image forming apparatus according to an eleventh aspect includes the optical scanning apparatus according to any one of the first to tenth aspects.

  According to the present invention, it is possible to realize an optical scanning device that is space-saving, has few components, can be reduced in cost, and is unlikely to generate an abnormal image due to flare light, and an image forming apparatus using the optical scanning device.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings. The present invention is not limited to the illustrated image forming apparatus, and can be applied to various apparatuses that perform image formation.

  FIG. 12 is a schematic configuration diagram showing a cross section of the image forming apparatus. In FIG. 12, an image forming apparatus 1 which is a tandem full-color machine includes a photosensitive member 3 as an image carrier, a charging device 2, a developing device 5 as a developing unit, a cleaning device 7 for cleaning the photosensitive member 3, and a static upper member of the photosensitive member 3. The image forming unit 20 includes an optical scanning device 10 for writing an electrostatic latent image. In addition, the image forming unit 20 includes a transfer roller 6 that faces the photoconductor 3 with the transfer conveyance belt 6a interposed therebetween. The transfer roller 6 forms a transfer nip with the photoreceptor 3 via the transfer conveyance belt 6a. Further, a toner bottle 20a is provided for storing replenishment toner to be supplied to the developing device 5 that consumes toner.

  A paper feed unit 40 is provided below the image forming unit 20. The paper feed unit 40 includes a paper feed cassette 11 which is a recording material storage unit and a paper feed roller 11a, and the paper feed cassette 10 stacks transfer paper S as a recording material on a stacking surface. . The sheet feeding roller 11a is for separating and feeding the transfer sheets S stacked on the sheet feeding cassette 10 one by one. The transfer paper S fed by the paper feed roller 11a is temporarily put on standby at the position of the registration roller 12 in front of the photoconductor 3. Then, the rotation of the photosensitive member 3 is performed at the timing when the leading edge of the image formed on the photosensitive member 3 and the leading edge of the transfer sheet S reach the transfer nip that is the nip portion between the photosensitive member 3 and the transfer roller 6 almost simultaneously. It is fed in synchronization with

  Further, above the image forming unit 20, a fixing device 9 is provided as a fixing unit including two rollers that form a fixing nip so as to rotate in pressure contact with each other across the conveyance path of the transfer paper S. A discharge roller 18 for discharging the transfer sheet S that has passed through the fixing nip to the discharge tray 8 is provided downstream of the fixing device 9 in the transfer sheet conveyance direction.

  A reading unit 30 is provided further above the image forming unit 20. The reading unit 30 includes a first traveling body 32 including a document illumination light source 32a and a first mirror 32b, and a second mirror for scanning a document (not shown) placed on the contact glass 31. A second traveling body 35 including 35a and a third mirror 35b is provided. The image information of the original scanned by the first traveling body 32 and the second traveling body 35 is read as an image signal into the CCD 34 installed behind the lens 33, and the read image signal is digitized. Image processing is performed. Based on the image-processed signal, a light source of an optical scanning device 10 to be described later emits irradiation light, and the irradiation light scans the surface of the photosensitive member 3 to form an electrostatic latent image on the surface of the photosensitive member 3. Is done.

Next, an image forming operation of the image forming apparatus will be described.
In the image forming apparatus, first, the photoreceptor 3 is uniformly charged by the charging device 2 during rotation. Next, the optical scanning device 10 is driven based on image information input from the outside, whereby an electrostatic latent image is formed in the charged area (image forming area) of the photoreceptor 3. This electrostatic latent image is developed by a developer (toner) supplied from the developing roller 5a of the developing device 5 to become a visible toner image.

  On the other hand, while the toner image is being formed on the photosensitive member 3, the transfer paper S is pulled out from the selected one of the plurality of paper feed cassettes 11 by the paper feed roller 11a, and the leading edge of the transfer paper S is removed. It waits in a state where it is in contact with the nip portion of the registration roller 12. When the registration roller 12 starts rotating at the timing when the toner image is superimposed on the photoconductor 3, the transfer paper S is sent out to a transfer nip formed by the photoconductor 3 and the transfer roller 6. Then, after the toner image on the photoconductor 3 is transferred at the transfer nip, it is discharged by contact with a discharging brush (not shown). The transfer sheet S that has been neutralized is mechanically separated from the photoreceptor 3 and then sent to the fixing device 9.

  The fixing device 9 sandwiches the transfer paper S between two rollers, thereby heating and pressurizing the transfer paper S to fix the toner image on the transfer paper S. The transfer sheet S on which the toner image is fixed in this manner is discharged onto the discharge tray 8 by the discharge roller 18.

  On the other hand, residual toner remaining on the surface of the photoreceptor 3 after passing through the transfer nip is removed from the photoreceptor 3 by the cleaning device 7 and collected.

  In the above description, the function as a copying machine of the image forming apparatus that reads the image information of the document placed on the contact glass 31 with the reading unit 30 and forms an image based on the image information has been described. The image forming apparatus has not only a function as a copying machine but also a function as a printer that forms an image based on image information input from an external electronic device such as a personal computer.

  The apparatus shown in FIG. 1 is a cross-sectional view of a counter scanning optical scanning apparatus used in a tandem full-color machine in which a deflector is arranged at the center. This will be described as an example of an embodiment of the invention.

  FIG. 2 is a perspective view of a part of the optical scanning device. The light source 201 is directly held by the optical housing 200, and the light beam from the light source 201 is made into substantially parallel light by the coupling lens 202. The light beam from the coupling lens 202 is shaped by the aperture 203 and enters the cylindrical lens 204. The cylindrical lens 204 condenses the shaped light beam into a line image, and the light beam after passing through the cylindrical lens 204 is deflected and scanned by the polygon scanner 205. The deflected and scanned light beam is imaged on the latent image carrier by the imaging lens 206 to form a latent image.

  On the opposite side of the light source 201, the light source 201 is laid out at the same position in the main scanning direction and at different positions in the sub scanning direction. Since it is directly attached to the optical housing 200 without providing a light source unit, space saving can be realized. Further, since the positions are the same in the main scanning direction, it is not necessary to install a folding mirror between the light source 201 and the polygon scanner 205, and the number of parts can be reduced.

  As shown in FIG. 3, the light beam L from the light source 201 is divergent light and is made substantially parallel light by the coupling lens 202, but the light beam L diverging larger than the outer diameter of the coupling lens 202 is It is reflected by the optical element without being shielded and becomes stray light. The light beam L that is not shielded is repeatedly reflected and may reach the photosensitive member 3 as a latent image carrier and become an abnormal image. However, as shown in FIG. 4, the aperture 203 provided integrally with the optical housing 200 is provided. By blocking the divergent light from the light source 201 on the peripheral wall, the light flux L passing through other than the aperture 203 is eliminated, and an abnormal image due to flare light can be suppressed.

  Further, since the light beam from the light source 201 is diverging light, it may be reflected by the inner surface of the coupling lens 202 and become stray light. Therefore, a light beam reflected by the coupling lens 202 can be shielded by providing a shape as shown in FIG. 5 on the wall around the aperture 203 integrated with the optical housing 200 and surrounding the coupling lens 202. is there.

  Furthermore, the light shielding degree can be increased by connecting the light source 201 and the coupling lens 202 by connecting to the wall to which the light source is attached as shown in FIG.

  Since the above-mentioned shapes utilize a part of the wall forming the aperture, the mold configuration is simple and the dimensional accuracy of the molded product is stabilized. Further, the degree of freedom of the shape is high, the shape can be freely changed according to the divergence angle of the light source and the size of the coupling lens, and light can be reliably shielded under any conditions.

  The deflection direction of the light source 201 differs depending on the light source 201, and when a 2ch-LDA (amplifier separation type digital laser sensor) is used, the beam pitch on the latent image carrier needs to be a desired pitch. There are constraints on the direction. In that case, it is conceivable that light cannot be shielded even if the wall around the aperture is raised. However, as shown in FIG. It is possible to shield light even with a light beam. A wall around the plate 701 and the aperture 203 as separate members is provided so as to surround the coupling lens 202 as described above (FIG. 8), and further, the plate 701 is connected to the wall to which the light source 201 is attached ( In FIG. 9), the light shielding degree can be further increased.

  With such a configuration, flare light can be reliably suppressed and good image quality can be obtained, and the adjusted coupling lens is protected from contact during assembly and adjusted. The position of the coupling lens can be maintained, and good image quality can be maintained.

  By the way, when the optical scanning device of the same optical system is used for different image forming apparatuses, the beam spot diameter on the latent image carrier is changed according to the conditions of the image forming process, so that there is no difference between different image forming apparatuses. A latent image may be obtained. In that case, it is possible to cope with the change in the shape and size of the aperture. If the aperture is configured separately from the optical housing, selecting the aperture according to the model makes it possible to easily create a model that can be used for different models while achieving many commonality. In production, as the number of common parts increases, the assemblability is simplified and the cost reduction effect by mass production can be obtained.

  When the aperture is a separate part, it is easy to make the component 1001 in which the aperture 203 and the plate 701 are integrated as shown in FIG. 10, and the number of parts can be reduced and the cost can be reduced while reliably suppressing flare light. Can be planned. Further, if the wall around the aperture 203 is provided so as to surround the coupling lens 202 as shown in FIG. 10, it is possible to shield the reflected light from the coupling lens 202.

  Similarly, the light shielding degree can be increased by connecting the wall around the aperture 202 to the wall to which the light source 201 is attached to surround the light source 201 and the coupling lens 202 as shown in FIG.

Cross-sectional view of counter scanning optical scanning device 1 is a perspective view of a part of the optical scanning device in FIG. 1 is an enlarged perspective view of a first example of a part of the optical scanning device of FIG. FIG. 2 is an enlarged perspective view of a second example of a part of the optical scanning device of FIG. FIG. 3 is an enlarged perspective view of a third example of a part of the optical scanning device in FIG. 1. An enlarged perspective view of a fourth example of a part of the optical scanning device of FIG. An enlarged perspective view of a fifth example of a part of the optical scanning device of FIG. An enlarged perspective view of a sixth example of a part of the optical scanning device of FIG. An enlarged perspective view of a seventh example of a part of the optical scanning device of FIG. FIG. 1 is an enlarged perspective view of an eighth example of part of the optical scanning device of FIG. An enlarged perspective view of a ninth example of part of the optical scanning device of FIG. Schematic configuration diagram showing a cross section of an image forming apparatus

Explanation of symbols

200: Optical housing 201: Light source 202: Coupling lens 203: Aperture 204: Cylindrical lens 205: Polygon scanner 206: Imaging lens 701: Plate 1001: Component part in which the aperture and the plate are integrated L: Light beam

Claims (11)

At least, a light source, a coupling lens for coupling a light beam emitted from the light source, an aperture unit for shaping the light beam from the light source into a desired shape, and a deflector for scanning the light beam from the light source In an optical scanning device comprising an optical element that forms an image of a light beam deflected by the deflector into a desired shape, and an optical housing including them.
An optical scanning device characterized in that a wall around an aperture portion provided in the optical housing blocks a light beam outside the coupling lens among light beams emitted from the light source. 2. The optical scanning device according to claim 1, wherein the aperture portion is formed integrally with the optical housing. 3. The optical scanning device according to claim 1, wherein the coupling lens is surrounded by the wall of the portion where the aperture portion is provided. 3. The optical scanning device according to claim 1, wherein the wall of the portion where the aperture portion is provided surrounds the emission portion of the light source. 3. The optical scanning device according to claim 1, wherein a light shielding plate is attached to an upper part of a wall around the aperture portion. 6. The optical scanning device according to claim 5, wherein a wall around the aperture portion surrounds the coupling lens. 6. The optical scanning device according to claim 5, wherein a wall around the aperture portion surrounds an emission portion of the light source. 2. The optical scanning device according to claim 1, wherein the aperture part is a separate member from the optical housing, the wall around the aperture part is surrounded by the coupling lens, and a light shielding plate is attached to the upper part of the wall. An optical scanning device. 2. The optical scanning device according to claim 1, wherein the aperture portion is a separate member from the optical housing, a wall around the aperture portion surrounds the emission portion of the light source, and a light shielding plate is attached to the upper portion of the wall. An optical scanning device. 10. The optical scanning device according to claim 8, wherein the aperture portion and the plate are made of the same component. An image forming apparatus comprising the optical scanning device according to claim 1.