JP2010191047A - Optical scanner and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner in which the warpage of a rid member caused when fixed on a housing or by the influence of a variation in temperature is prevented, suitable light beam irradiation is performed and a high quality image is obtained. <P>SOLUTION: The optical scanner 20 includes: the housing 21 in which optical equipment which irradiates a face to be scanned with the light beam is equipped; and the thin plate-shaped rid member 24 which covers the open part of the housing 21 wherein the rid member 24 is split into a plurality of parts, and each rid member 24 is individually fixed to the housing 21. Thus, the size of each rid member 24a to 24d is small with respect to the open part of the housing 21, and the generation of warpage is suppressed. Furthermore, even if the rid members 24 are expanded or contracted due to the variation in the temperature of the housing 21, the expansion and the contraction of the rid members 24 are adjustable between the adjacent rid members 24. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical scanning device that is mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile machine, and exposes and scans the surface of an image carrier with a light beam (for example, laser light). The present invention also relates to an image forming apparatus equipped with this optical scanning device.

  An optical scanning device mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile is generally exposed while scanning the surface of an image carrier represented by a photosensitive drum, that is, a scanned surface. A predetermined electrostatic latent image is formed on the drum surface. In an optical scanning device, a light beam such as laser light emitted from a light source is deflected in a main scanning direction by an optical deflector and emitted toward a surface to be scanned by a reflecting mirror.

  The optical scanning device includes a housing and an optical device that irradiates a surface to be scanned with a light beam such as a light source, an optical deflector, a lens, and a reflection mirror in the housing. The housing has a box shape with one side open, and an optical device is inserted into the inside from the open portion when the apparatus is assembled. The open portion of the housing is provided with a thin plate-shaped lid member that serves as a cover so that dust such as toner scattered in the image forming apparatus such as a copying machine or a printer does not enter the optical scanning device. The part is blocked. An example of the optical scanning device having such a configuration can be seen in Japanese Patent Application Laid-Open No. 2004-133830.

JP 2006-154228 A (6th page, FIG. 2)

  In the optical scanning device (optical scanning unit) described in Patent Document 1, a lid member (upper surface cover) is provided on a housing (unit main body) having an open portion on the upper surface, so that optical devices inside the housing are scattered. Good light beam irradiation can be performed without being adversely affected by dust such as toner. However, since the lid member of such an optical scanning device has a relatively wide flat surface portion and is fixed to the housing only at its peripheral edge so as not to interfere with the light beam that scans within the housing. There is a risk of warping in which the central portion is bent during fixing.

  Here, in the optical scanning device described in Patent Document 1, an opening through which a light beam irradiated by an optical device travels to a surface to be scanned is provided in a lid member (upper surface lid). Since the light beam needs to be deflected in the main scanning direction, that is, the axial direction of the photosensitive drum, the opening provided in the housing has a relatively long shape in the axial direction of the photosensitive drum. The opening is provided with a light-transmitting member such as dust-proof glass so that dust such as scattered toner does not enter the housing.

  As described above, when the lid member is warped when the lid member is fixed, there is a high possibility that the dust-proof glass is also distorted. As a result, there is an adverse effect that the scanning line is bent on the light beam, and the problem of image quality degradation occurs. Therefore, the optical scanning device suppresses warpage that may occur in the lid member when the scanning line cannot be adjusted by operating the lens or mirror inside the lid member after the lid member is fixed to the housing. An elaborate design is required.

  In recent years, image forming apparatuses capable of high-speed printing have become widespread. The optical scanning device also needs to operate correspondingly, and it is necessary to rotate the polygon mirror, which is a rotating polygon mirror of the optical deflector, at high speed. For this reason, in the optical scanning device, the amount of heat generated at the position of the optical deflector becomes large, and the entire housing may be affected by the temperature change. That is, the lid member fixed to the housing may expand and contract due to a temperature change, and there is a concern that warping may occur due to this.

  The present invention has been made in view of the above points, and in an optical scanning device including a thin-plate-shaped lid member that covers an open portion of a housing that includes an optical device, the lid member is fixed to the housing or at a temperature. An object of the present invention is to provide an optical scanning apparatus that can prevent warping caused by the influence of changes, perform suitable light beam irradiation, and obtain a high-quality image. Another object of the present invention is to provide a high-performance image forming apparatus equipped with such an optical scanning device.

  In order to solve the above problems, the present invention provides an optical scanning device including a housing that includes an optical device that irradiates a scanned surface with a light beam and a lid member that covers an open portion of the housing. The lid member is divided into a plurality of parts, and each lid member is individually fixed to the housing.

  In the optical scanning device having the above-described configuration, the lid member is configured such that adjacent portions of adjacent lid members overlap each other.

  In the present invention, the optical scanning device is mounted on an image forming apparatus.

  According to the configuration of the present invention, in the optical scanning device including a housing that includes an optical device that irradiates the surface to be scanned with a light beam, and a lid member that covers an open portion of the housing, the lid member includes Since each of the lid members is individually fixed to the housing, the size of each lid member is reduced with respect to the open portion of the housing, and the occurrence of warpage can be suppressed. Thereby, distortion of the dust-proof glass provided in the lid member can be suppressed, and the scanning line can be prevented from being curved. Further, even if the lid member expands and contracts due to a change in the temperature of the housing, the expansion and contraction of the lid member can be adjusted between the adjacent lid members. Therefore, it is possible to prevent the warp caused by the expansion and contraction of the lid member. In this way, it is possible to prevent the warpage caused by the lid member being fixed to the housing or affected by temperature changes, and to perform suitable light beam irradiation, thereby obtaining a high-quality image. An optical scanning device can be provided.

  Moreover, since the said cover member decided that the adjacent location of the adjacent cover member overlaps, a clearance gap produces between adjacent cover members, and the distribution | circulation of air becomes easy between the inside and the exterior of a housing. Can be prevented. Thereby, it is possible to prevent dust such as scattered toner from entering the housing from between adjacent lid members. Accordingly, the optical scanning device has an effect of preventing dust from entering the housing in addition to the effect of suppressing the warping of the lid member, and can perform more suitable light beam irradiation, and can further improve the quality of the image. It becomes possible to obtain.

  Further, in the present invention, since the optical scanning device is mounted on the image forming apparatus, it is possible to prevent the warpage caused by the influence of the lid member of the optical scanning device when it is fixed to the housing or due to the temperature change. Therefore, it is possible to provide a high-performance image forming apparatus that can perform irradiation with a light beam and obtain a high-quality image.

1 is a schematic vertical sectional front view of an image forming apparatus equipped with an optical scanning device according to an embodiment of the present invention. It is a model vertical cross section front view of the optical scanning device shown in FIG. FIG. 3 is a schematic top view of the optical scanning device shown in FIG. 2. It is the perspective view seen from the back upper part of the optical scanning device. It is a rear view of the optical scanning device shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an image output operation of an image forming apparatus equipped with an optical scanning device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic vertical sectional front view of an image forming apparatus. This image forming apparatus is of a color printing type in which a toner image is transferred onto a sheet using an intermediate transfer belt.

  As shown in FIG. 1, a paper feed cassette 3 is disposed below the inside of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates paper P such as cut paper before printing. The sheets P are separated and sent one by one toward the upper left of the sheet cassette 3 in FIG. The paper feed cassette 3 can be pulled out horizontally from the front side of the main body 2.

  A first paper transport unit 4 is provided inside the main body 2 and to the left of the paper feed cassette 3. The first paper transport unit 4 is formed substantially vertically along the left side surface of the main body 2. The first paper transport unit 4 receives the paper P sent out from the paper feed cassette 3 and transports the paper P vertically upward along the left side surface of the main body 2 to the secondary transfer unit 9.

  A manual paper feed unit 5 is provided above the paper feed cassette 3 at a location on the right side which is the side opposite to the left side of the main body 2 where the first paper transport unit 4 is formed. Yes. In the manual paper feed unit 5, paper of a size that is not in the paper feed cassette 3, or paper that is to be manually fed, such as thick paper and OHP sheets, is placed.

  A second paper transport unit 6 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 6 is located immediately above the paper feed cassette 3, extends substantially horizontally from the manual paper feed unit 5 to the first paper transport unit 4, and joins the first paper transport unit 4. The second paper transport unit 6 receives the paper sent out from the manual paper feed unit 5 and transports it to the first paper transport unit 4 substantially horizontally.

  On the other hand, the image forming apparatus 1 receives document image data from an external computer (not shown). The information of the image data is sent to the optical scanning device 20 that is an exposure unit disposed above the second paper transport unit 6. The laser beam L controlled based on the image data is emitted toward the image forming unit 30 by the optical scanning device 20.

  A total of four image forming units 30 are provided above the optical scanning device 20, and an intermediate transfer belt 7 using an intermediate transfer member in the form of an endless belt is provided above each image forming unit 30. The intermediate transfer belt 7 is supported by being wound around a plurality of rollers, and is rotated clockwise in FIG. 1 by a driving device (not shown).

  As shown in FIG. 1, the four image forming units 30 are of a so-called tandem type arranged in a line from the upstream side in the rotational direction to the downstream side in the rotational direction of the intermediate transfer belt 7. The four image forming units 30 are, in order from the upstream side, a yellow image forming unit 30Y, a magenta image forming unit 30M, a cyan image forming unit 30C, and a black image forming unit 30B. These image forming units 30 are replenished with a developer (toner) by a developer supply container and a conveying unit (not shown) corresponding to each color. In the following description, the identification symbols “Y”, “M”, “C”, and “B” are omitted unless particularly limited.

  In each image forming unit 30, an electrostatic latent image of a document image is formed by the laser light L emitted by the optical scanning device 20 that is an exposure unit, and a toner image is developed from the electrostatic latent image. The toner image is primarily transferred to the surface of the intermediate transfer belt 7 by the primary transfer unit 8 provided above each image forming unit 30. Then, as the intermediate transfer belt 7 rotates, the toner image of each image forming unit 30 is transferred to the intermediate transfer belt 7 at a predetermined timing, so that the surface of the intermediate transfer belt 7 has four colors of yellow, magenta, cyan, and black. A color toner image is formed by superimposing the color toner images.

  A secondary transfer unit 9 is disposed at a position where the intermediate transfer belt 7 is suspended on the sheet conveyance path. The color toner image on the surface of the intermediate transfer belt 7 is transferred to the paper P sent in synchronization by the first paper transport unit 4 at the secondary transfer nip portion formed in the secondary transfer unit 9.

  After the secondary transfer, deposits such as toner remaining on the surface of the intermediate transfer belt 7 are cleaned for the intermediate transfer belt 7 provided on the upstream side in the rotation direction of the yellow image forming portion 30Y with respect to the intermediate transfer belt 7. It is cleaned and collected by the apparatus 10.

  A fixing device 11 is provided above the secondary transfer unit 9. The sheet P carrying the unfixed toner image in the secondary transfer unit 9 is sent to the fixing device 11 where the toner image is heated and pressed by a heat roller and a pressure roller to be fixed.

  A branch portion 12 is provided above the fixing device 11. The sheet P discharged from the fixing device 11 is discharged from the branching unit 12 to the sheet discharging unit 13 provided at the upper part of the image forming apparatus 1 when double-sided printing is not performed.

  The discharge port portion from which the paper P is discharged from the branch portion 12 toward the paper discharge portion 13 functions as the switchback portion 14. When performing duplex printing, the switchback unit 14 switches the transport direction of the paper P discharged from the fixing device 11. Then, the sheet P is sent downward through the branching unit 12, the left side of the fixing device 11, and the left side of the secondary transfer unit 9, and again passes through the first sheet transport unit 4 to the secondary transfer unit 9. Sent.

  Next, the outline of the structure of the optical scanning device 20 of the image forming apparatus 1 will be described with reference to FIGS. 2 is a schematic vertical sectional front view of the optical scanning device, FIG. 3 is a schematic top view of the optical scanning device, and FIG. 4 is a perspective view of the optical scanning device viewed from the upper rear side. 2 and 3, the drawing of the lid member arranged on the upper surface of the optical scanning device shown in FIG. 4 is omitted.

  As described above, the optical scanning device 20 is designed to be mounted on the tandem type image forming apparatus 1 provided with four photosensitive drums corresponding to four colors of yellow, magenta, cyan, and black. Is.

  As shown in FIGS. 2 and 3, the optical scanning device 20 includes a light source 22, an optical deflector 40, an optical member group 50, and an optical sensor 23 inside a box-shaped housing 21 whose upper surface is formed as an open portion. An optical device composed of

  The housing 21 has a box shape with an upper surface formed as an open portion. A thin plate-shaped lid member 24 shown in FIG. 4 is attached to the upper surface of the housing 21 so as to cover and close the open portion. Both the housing 21 and the lid member 24 are made of synthetic resin.

  The light source 22 is provided on one end side of the housing 21, that is, on the right end side in FIG. The optical scanning device 20 corresponds to four colors of yellow, magenta, cyan, and black, and four independent light sources 22 are provided. The light source 22 is composed of a laser diode having a specification for irradiating a visible region light beam, for example, a laser beam of about 670 nm.

  The optical deflector 40 is provided in the vicinity of the light source 22 and on one end side of the housing 21, that is, on the right end side in FIG. The optical deflector 40 includes a polygon mirror 41 that is a rotating polygon mirror and a motor 42. The motor 42 rotates the polygon mirror 41 having a regular polygonal plane shape around the axis in the vertical direction in FIG. A plurality of reflecting surfaces for reflecting light are provided around the polygon mirror 41 that rotates about the axis.

  The laser beams LY, LM, LC, and LB emitted from the four light sources 22 are incident on the reflection surface around the polygon mirror 41 while being shifted by a minute angle in the sub-scanning direction (vertical direction in FIG. 2). . While rotating, the polygon mirror 41 reflects each laser beam on its reflecting surface and deflects it in the main scanning direction (vertical direction in FIG. 3), while at the other end in the housing 21, that is, the left in FIGS. Lead towards the direction.

  The optical member group 50 is provided in a region in the housing 21 where the laser light reflected by the optical deflector 40 travels. The optical member group 50 includes a first fθ lens 51, a second fθ lens 52, and a reflection mirror 53.

  The first fθ lens 51 is disposed at a position immediately ahead where the laser beams LY, LM, LC, and LB reflected by the optical deflector 40 travel. The first fθ lens 51 is shared by the laser beams LY, LM, LC, and LB, and one first fθ lens 51 is provided. In the first fθ lens 51, the laser beams LY, LM, LC, and LB are deflected at a constant speed in the main scanning direction. Furthermore, the first fθ lens 51 corrects the adverse effects on the scanning such as the incident angles of the laser beams LY, LM, LC, and LB to the polygon mirror 41 and the surface tilt of the polygon mirror 41, while correcting the laser beams LY, LM, and LC. , Slightly increase the angle of LB in the sub-scanning direction.

  The yellow laser light LY that has passed through the first fθ lens 51 is reflected by the reflection mirror 53Ya in the vicinity of the inner bottom surface of the housing 21 and is folded back toward the first fθ lens 51. Thereafter, the laser beam LY passes through the second fθ lens 52Y, is reflected by the reflection mirror 53Yb near the upper end of the housing 21, and reaches the surface of the yellow photosensitive drum 31Y, which is the scanning surface, to form an image.

  The magenta laser light LM that has passed through the first fθ lens 51 is also reflected by the reflection mirror 53Ma near the inner bottom surface of the housing 21 and folded back toward the first fθ lens 51, similarly to the yellow laser light LY. Thereafter, the laser beam LM passes through the second fθ lens 52M, is reflected by the reflection mirror 53Mb near the upper end of the housing 21, reaches the surface of the magenta photosensitive drum 31M, which is the scanning surface, and forms an image.

  The cyan laser light LC that has passed through the first fθ lens 51 is reflected substantially vertically upward by the reflecting mirror 53Ca in the vicinity of the inner bottom surface of the housing 21, and then substantially in the horizontal direction by the reflecting mirror 53Cb in the vicinity of the upper end of the housing 21. Then, it is folded in the direction of the first fθ lens 51. Thereafter, the laser beam LC passes through the second fθ lens 52C, is reflected by the reflection mirror 53Cc, and reaches the surface of the cyan photosensitive drum 31C, which is the scanning surface, to form an image.

  The black laser beam LB that has passed through the first fθ lens 51 passes through the second fθ lens 52B directly without passing through the reflection mirror. Thereafter, the laser beam LB is reflected by the reflection mirror 53B and reaches the surface of the black photosensitive drum 31B, which is the surface to be scanned, and forms an image.

  As shown in FIG. 3, the optical sensor 23 is disposed in the vicinity of the reflection mirror 53Ya and the second fθ lens 52M and closer to the outside in the main scanning direction. The optical sensor 23 receives a laser beam reflected by the polygon mirror 41 of the optical deflector 40 that is outside the effective exposure area of the surface to be scanned. The laser light received by the optical sensor 23 is reflected toward the optical sensor 23 by the reflection mirror 25 provided in the vicinity of the second fθ lens 52B. The optical sensor 23 is a synchronization detection sensor for measuring the scanning timing of the laser beams LY, LM, LC, and LB corresponding to the four colors, and is called a BD sensor.

  Next, the configuration of the lid member 24 of the optical scanning device 20 will be described in detail with reference to FIG. 5 in addition to FIG. FIG. 5 is a rear view of the optical scanning device.

  As shown in FIG. 4, the lid member 24 has an opening 26 through which laser beams LY, LM, LC, and LB, which are light beams emitted from the optical device, pass toward the surface of the photosensitive drum that is the surface to be scanned. Is provided. The opening 26 has a rectangular shape extending in the main scanning direction of the laser light, and four locations are provided corresponding to the laser lights LY, LM, LC, and LB. The four openings 26 are arranged side by side in the same manner as the four photosensitive drums 31 corresponding to the respective laser beams L are arranged.

  The four openings 26 are provided with dustproof glass 27 which is a light transmissive member. The dust-proof glass 27 has a rectangular parallelepiped shape that extends in the main scanning direction like the opening 26, and is provided so as to close the opening 26 so that dust such as scattered toner does not enter the housing 21 from the opening 26. Yes.

  The lid member 24 is divided into four as lid members 24 a to 24 d and arranged side by side in the laser beam sub-scanning direction, that is, the left-right direction of the optical scanning device 20. Each of the lid members 24a to 24d includes an opening 26 and a dustproof glass 27, and has a rectangular shape extending in the main scanning direction. The cover members 24 a to 24 d are fastened and fixed individually to the housing 21 by screws 28 at almost four corners.

  Moreover, the lid member 24 is configured in a shape provided with a step so that adjacent portions of the adjacent lid members 24 overlap each other. In this place, the adjacent lid members 24 are overlapped, and the two lid members 24 are fastened and fixed to the housing 21 with a common screw 28. Accordingly, the total number of screws 28 for fixing the four corners of the four lid members 24 is ten.

  As described above, in the optical scanning device 20 including the housing 21 that includes the optical device that irradiates the surface to be scanned with the optical beam and the lid member 24 that covers the open portion of the housing 21, the lid member 24. Is divided into a plurality of parts, and each lid member 24 is individually fixed to the housing 21, so that the size of the individual lid members 24a to 24d is smaller than the open portion of the housing 21, and the occurrence of warpage is suppressed. be able to. Thereby, distortion of the dust-proof glass 27 provided in the lid member 24 can be suppressed, and the scanning line can be prevented from being curved. Even if the lid member 24 expands and contracts due to a temperature change of the housing 21, the expansion and contraction of the lid member 24 can be adjusted between the adjacent lid members 24. Therefore, it is possible to prevent the occurrence of warping due to the expansion and contraction of the lid member 24. In this way, it is possible to prevent the warpage caused by the influence of the lid member 24 when it is fixed to the housing 21 or due to a temperature change, and to perform suitable light beam irradiation, thereby obtaining a high-quality image. Thus, the optical scanning device 20 capable of performing the above can be provided.

  Moreover, since the adjoining location of the adjacent lid member 24 overlaps with the lid member 24, a gap is generated between the adjacent lid members 24, and air circulation is facilitated between the inside and the outside of the housing 21. Can be prevented. Thereby, it is possible to prevent dust such as scattered toner from entering the housing 21 from between the adjacent lid members 24. Accordingly, the optical scanning device 20 has an effect of preventing dust from entering the housing 21 in addition to an effect of suppressing the warpage of the lid member 24, and can perform a more suitable light beam irradiation, thereby further improving the quality. Images can be obtained.

  Further, in the present invention, since the optical scanning device 20 is mounted on the image forming apparatus 1, the warpage caused by the influence of the lid member 24 of the optical scanning device 20 when it is fixed to the housing 21 or due to a temperature change is prevented. Therefore, it is possible to provide a high-performance image forming apparatus 1 that can perform suitable light beam irradiation and can obtain a high-quality image.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  For example, in the embodiment of the present invention, an optical scanning device mounted on a tandem type image forming apparatus provided with four photosensitive drums has been described as an example, but the target optical scanning device is in this form. However, the present invention is not limited thereto, and may be an optical scanning device mounted on another type of image forming apparatus.

  Further, the number and location of the lid member 24 to be divided, the number of screws 28 that are fastening members, and the fastening location are not limited to the configuration of the embodiment of the present invention, but may be configured with other quantities and locations. It doesn't matter.

  INDUSTRIAL APPLICABILITY The present invention can be used in an optical scanning device that includes a lid member that covers an open portion of a housing that includes an optical device.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20 Optical scanning device 21 Housing 22 Light source 24 Cover member 26 Opening part 27 Dust-proof glass 28 Screw 40 Optical deflector

Claims (3)

In an optical scanning device including a housing that internally includes an optical device that irradiates a surface to be scanned with a light beam, and a lid member that covers an open portion of the housing.
The lid member is divided into a plurality of parts, and each lid member is individually fixed to a housing.   The optical scanning device according to claim 1, wherein the lid member overlaps adjacent portions of adjacent lid members.   An image forming apparatus comprising the optical scanning device according to claim 1.

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