JP2017003918A - Optical scanner and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner that can prevent a stress from acting on a holding body due to provision of a light blocking member in the optical scanner, and an image forming apparatus including the same.SOLUTION: In a writing unit 100 being an optical scanner comprising: a scanning lens 57 being an optical system constituent member constituting part of an optical system through which a laser beam 13 being a light beam passes; a housing 101 being a holding body holding the optical system; and a light blocking member 61 that blocks, light beams emitted from the scanning lens 57, a flare light beam being a light beam directed to a path different from a predetermined path, only one end of the light blocking member 61 is fixed to the housing 101.SELECTED DRAWING: Figure 1

Description

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

  Image forming apparatuses such as printers, copiers, and facsimiles include an optical scanning device that deflects light emitted from a light source by a deflector, scans the light, and irradiates a photosensitive member to write a latent image. . Patent Document 1 includes a light shielding member that shields so-called flare light, which is light traveling from a fθ lens that forms part of an optical system through which a light beam passes, that is directed to a path different from a predetermined path. An optical scanning device is described.

In the optical scanning device described in Patent Document 1, a light shielding member is fixed to a holding body that holds an optical system constituent member such as an fθ lens with a both-ends fixing structure. In the case of the both-end fixed structure, when the distance between the fixed portions in the light shielding member and the distance between the fixed portions in the holding body are different due to the difference in expansion amount during thermal expansion, the light shielding member and the holding body Tensile stress or compressive stress acts on.
When deformation occurs due to the stress acting on the holding body, the optical system held by the holding body is displaced, and the irradiation position of the light beam with respect to the photosensitive body is displaced, and there is a possibility that the image is displaced.

  In order to solve the above-described problem, the invention of claim 1 includes an optical system constituent member that constitutes a part of an optical system through which light passes, a holding body that holds the optical system, and the optical system constituent member. An optical scanning device having a light shielding member that shields light that goes to a path different from a predetermined path among emitted light, wherein only one end of the light shielding member is fixed to the holding body. Is.

  According to the present invention, there is an excellent effect that stress can be prevented from acting on the holding body due to the provision of the light shielding member in the optical scanning device.

FIG. 4 is an enlarged explanatory view of the vicinity of a scanning lens and dust-proof glass of a writing unit. 1 is a schematic configuration diagram of a multifunction machine. The schematic block diagram of a writing unit. The enlarged perspective view of the polygon scanner vicinity of a writing unit. The perspective view which shows the optical path in which the reflected light in soundproof glass injects into a scanning lens as flare light. FIG. 3 is a side sectional view of a scanning lens showing an optical path from when flare light enters the scanning lens and exits. The expanded sectional view of the writing unit which shows the state in which the flare light radiate | emitted from the scanning lens upper surface permeate | transmits dust-proof glass. The enlarged perspective view of the attachment position vicinity of the light shielding member before attaching the light shielding member in a writing unit. FIG. 4 is an enlarged perspective view of the vicinity of the light shielding member in a state where the light shielding member is attached in the writing unit.

  Hereinafter, an embodiment of an electrophotographic image forming apparatus provided with a writing unit which is an optical scanning apparatus to which the present invention is applied will be described.

FIG. 2 is a schematic configuration diagram of a multi-function device 500 that is an image forming apparatus according to the present embodiment.
The multi-function device 500 includes an image forming unit 200, a paper feeding unit 400 disposed below the image forming unit 200, and a reading unit 300 disposed above the image forming unit 200.

The image forming unit 200 includes four image forming apparatuses 1 (Y, M, C, K) corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). Y, M, C, and K attached to the numbers of the respective symbols indicate members for yellow, magenta, cyan, and black (the same applies hereinafter). The four image forming apparatuses 1 (Y, M, C, and K) have substantially the same configuration except that the colors of the toners to be handled are different from each other. Therefore, “Y” indicating the color of the toner to be used will be described below. , “M”, “C”, and “K” are appropriately omitted.
The image forming apparatus 1 includes a photosensitive member 3 as an image carrier, a charging device 2 that charges the surface of the photosensitive member 3, a developing device 5 as a developing unit, and a cleaning device 7 that cleans the photosensitive member 3.

  The image forming unit 200 includes a writing unit 100 that writes an electrostatic latent image on the photoconductor 3 and an intermediate transfer belt 16 to which a toner image formed on the photoconductor 3 is transferred. Further, a primary transfer roller 6 is provided which forms a primary transfer nip so as to face the photoreceptor 3 with the intermediate transfer belt 16 interposed therebetween, and primarily transfers the toner image on the photoreceptor 3 to the intermediate transfer belt 16. Further, a secondary transfer roller 26 is provided for transferring the toner image on the intermediate transfer belt 16 onto a transfer sheet S as a recording material. A registration roller pair 12 for temporarily waiting for the transfer sheet S is provided upstream of the secondary transfer nip formed by the secondary transfer roller 26 and the intermediate transfer belt 16 in the transport direction of the transfer sheet S.

  The image forming unit 200 includes four toner bottles 20 (Y, M, C, and K) that store supply toner to be supplied to the developing devices 5 (Y, M, C, and K) that consume toner. A fixing device 9 as a fixing unit is provided above the secondary transfer roller 26, and a discharge roller 18 is provided on the downstream side of the fixing device 9 in the transport direction of the transfer paper S.

  The paper feed unit 400 includes a paper feed cassette 10 that is a recording material storage unit and a paper feed roller 11, and the paper feed cassette 10 stacks transfer sheets S on a stacking surface. The paper feed roller 11 is for separating and feeding the transfer paper S stacked on the paper feed cassette 10 one by one.

  The reading unit 300 includes a contact glass 31 on which a document is placed. Further, in order to read and scan a document placed on the contact glass 31, a first traveling body 32 including a document illumination light source 32a and a first mirror 32b, a second mirror 35a, and a third mirror 35b are provided. A second traveling body 35 provided. Furthermore, a lens 33 and a CCD 34 installed behind the lens 33 are provided.

Next, an image forming operation of the multi-function device 500 will be described.
When an original is placed on the contact glass 31 and an image forming operation is started, the original illumination light source 32a emits light. The reflected light reflected by the original is reflected by the first mirror 32b, the second mirror 35a, and the third mirror 35b, passes through the lens 33, and enters the CCD 34. The reading unit 300 generates image information to be formed on the transfer sheet S based on the reflected light received by the CCD 34.

  In the image forming unit 200, the photoreceptor 3 is uniformly charged by the charging device 2 during rotation. Next, the writing unit 100 is driven based on the image information generated by the reading unit 300. In the writing unit 100, the light source emits irradiation light, and the irradiation light scans the surface of the photoconductor 3, whereby an electrostatic latent image is formed on the charged area (image forming area) of the photoconductor 3. This electrostatic latent image is developed by a developer (toner) supplied from the developing roller 15 of the developing device 5 to become a toner image as a visible image.

  On the other hand, while the toner image is being formed on the photoreceptor 3, the transfer sheet S is pulled out from the selected one of the plurality of paper feed cassettes 10 by the paper feed roller 11, and the leading edge of the transfer paper S is pulled out. It waits in the state contact | abutted to the nip part of the registration roller pair 12. FIG. Then, at the primary transfer nip, the registration roller pair 12 starts rotating at the timing when the toner images transferred so that the toner images of the respective colors are superimposed on the intermediate transfer belt 16 from the photoreceptor 3 are superimposed. The transfer sheet S is sent out to the secondary transfer nip. The transfer sheet S on which the toner image is transferred at the secondary transfer nip is neutralized by contact with the neutralizing brush, mechanically separated from the intermediate transfer belt 16, and then sent to the fixing device 9.

The fixing device 9 includes two rollers that form a fixing nip so as to be pressed against each other across the conveyance path of the transfer paper S, and the transfer paper S is heated by sandwiching the transfer paper S between the two rollers. And pressurizing to fix the toner image on the transfer paper S. The transfer sheet S on which the toner image is fixed by passing through the fixing device 9 is discharged onto the discharge tray 8 by the discharge roller 18.
Residual toner remaining on the surface of the photoreceptor 3 after passing through the primary 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 multi-function device 500 that reads image information of a document placed on the contact glass 31 with the reading unit 300 and forms an image based on the image information has been described. The multi-function device 500 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.

  In the multi-function device 500 that is the image forming apparatus of the embodiment, the latent image formed on the photosensitive member 3 is developed into a toner image that is a visible image, and then is passed through the intermediate transfer belt 16 that is an intermediate transfer member. After the toner image is transferred to the transfer paper S, the toner image on the transfer paper S is fixed to obtain an image. The method of transferring the toner image to the transfer paper S is not limited to the intermediate transfer method via the intermediate transfer member, and may be a direct method of transferring the toner image directly from the photosensitive member to the transfer paper S. In a direct transfer type color image forming apparatus, a latent image formed on each photoconductor is developed and visualized, and then a transfer material such as a recording sheet carried on a transfer conveyance belt or the like is transferred to each photoconductor. To the transfer section. Each color visible image formed on each photoconductor is transferred onto the transfer material in an overlapping manner, and the visible image transferred onto the transfer material is fixed to obtain an image.

Next, the writing unit 100 will be described.
FIG. 3 is a schematic configuration diagram of the writing unit 100 of the present embodiment provided in the multi-function device 500. In the multi-function device 500 shown in FIG. 2, the writing unit 100 is arranged in an inclined state, but in FIG. 3, it is shown in an inclining state for convenience.

  The writing unit 100 includes a reflection mirror on the side of a regular polygon that rotates at high speed, and includes a polygon scanner 56 that deflects and scans the laser light incident on the reflection mirror. Further, the installation portion of the polygon scanner 56 is a sealed space, and a soundproof glass 55 is provided for suppressing noise when the polygon scanner 56 is driven to rotate the reflection mirror. Further, a resin-made scanning lens 57 that is an imaging optical element and has an fθ correction function, and a first reflecting mirror 80 and a second reflecting mirror 81 for guiding the laser light that has passed through the scanning lens 57 to the photosensitive member 3; .

The writing unit 100 includes a housing 101 that is an optical housing that forms an optical box that is a resin holder on which the above-described members are disposed, and an upper cover 102 and a lower cover 103 for sealing the housing 101. Prepare. “13” in FIG. 3 indicates the optical path of the laser beam for exposing the photoreceptor 3 of each color.
In the writing unit 100, a dust-proof glass 59 that prevents falling of dust and the like into the housing 101 is disposed at the opening of the upper cover 102 through which the laser beam 13 passes. The member through which the laser beam 13 disposed in the opening of the upper cover 102 transmits is not limited to a flat glass member such as the dustproof glass 59. As long as the laser beam 13 can be transmitted and the fall of dust or the like into the housing 101 can be prevented, a shape other than a flat plate shape or a material such as a resin other than glass may be used.

FIG. 4 is an enlarged perspective view of the vicinity of the polygon scanner 56 of the writing unit 100.
As shown in FIG. 4, the writing unit 100 includes a light source unit 51, and includes a coupling lens 52, an aperture 53, and a pre-polygon optical system installed in the path of the laser beam 13 from the light source unit 51 to the polygon scanner 56. A cylindrical lens 54 is provided. The light source unit 51 can use a semiconductor laser as a light source, but the light source is not limited to this.

The laser beam 13 incident on the polygon scanner 56 is emitted from the light source unit 51, converted from a divergent beam into a parallel beam by the coupling lens 52, and shaped by the aperture 53. Next, the laser beam 13 is condensed in the sub-scanning direction by the cylindrical lens 54, passes through the soundproof glass 55, and enters the polygon scanner 56. The laser beam 13 incident on the polygon scanner 56 is deflected and travels toward the scanning lens 57.
As shown in FIG. 1, the laser beam 13 that has passed through the scanning lens 57 is reflected by the first reflecting mirror 80 and the second reflecting mirror 81, passes through the dust-proof glass 59, and exposes the surface of the photoreceptor 3.

The coupling lens 52 and the cylindrical lens 54 are adjusted to have desired optical characteristics and then fixed to the housing 101 with an adhesive. The light source 51, aperture 53, soundproof glass 55, polygon scanner 56, scanning lens 57, first reflection mirror 80 and second reflection mirror 81 are also fixed to the housing 101.
As described above, the optical system components are attached to the housing 101 that is a single casing, and the housing 101 is covered with the upper cover 102 and the lower cover so that dust and dust do not adhere to the optical system components. Covered with a cover 103. Further, an opening provided in the upper cover 102 that is an optical path through which the laser beam 13 passes is provided with a dustproof glass 59, and the photosensitive member is irradiated with the laser beam 13 in a state where the space where the optical system components are arranged is sealed. It has a configuration.

  The writing unit 100 according to the present embodiment is an optical scanning device used in the multi-function device 500 that is a color image forming apparatus, and includes a plurality of light source units 51, a scanning lens 57, and the like so as to face each color. ing. In the present embodiment, a plurality of light source units 51, a scanning lens 57, and the like are accommodated in a housing 101 that is a single casing.

In the writing unit 100, in addition to the laser beam 13 for forming a latent image on the photoconductor 3, a so-called flare that deviates from the normal optical path due to surface reflection of an optical element from the light source unit 51 to the photoconductor 3. Light may be generated. When this flare light reaches the photosensitive member 3 and the surface of the photosensitive member 3 is exposed, an abnormal image such as a vertical stripe is formed.
As a countermeasure, exposure to the photoreceptor 3 can be shielded by providing a shield on the optical path of flare light. As a method of providing a shielding object, when the shielding object is affixed on the scanning lens 57, the scanning lens 57 is stressed when the temperature rises due to the difference in linear expansion coefficient between the scanning lens 57 and the shielding object, and the scanning line profile changes. There is a risk.

FIG. 5 is a perspective view showing an optical path in which reflected light from the soundproof glass 55 enters the scanning lens 57 as flare light 13a.
The laser beam 13 transmitted through the cylindrical lens 54 enters the soundproof glass 55. Since the soundproof glass 55 has a transmittance of 80% or more, most of the incident laser light 13 is transmitted as shown by the broken line in FIG. However, a part of the laser light 13 that does not transmit is reflected by the surface of the soundproof glass 55 as flare light 13a, as indicated by the solid line arrow in FIG.

FIG. 6 is a side sectional view of the scanning lens 57 showing an optical path from the time when the flare light 13a is incident on the scanning lens 57 and is emitted.
As shown in FIG. 6, the flare light 13a reflected by the soundproof glass 55 is incident on the scanning lens 57, and the sinking portion 41 on the scanning lens upper surface 57a, the scanning lens exit surface 57b, and the sinking portion 41 on the scanning lens lower surface 57c. Each is reflected. Then, the light is emitted from the scanning lens upper surface 57a or the scanning lens incident surface 57d. FIG. 6 shows an example in which the flare light 13a is emitted from the scanning lens upper surface 57a.

FIG. 7 is an enlarged cross-sectional view of the writing unit 100 showing a state in which the flare light 13 a emitted from the scanning lens upper surface 57 a passes through the dust-proof glass 59.
As shown in FIG. 7, when the flare light 13a emitted from the upper surface 57a of the scanning lens passes through the dust-proof glass 59, the flare light 13a reaches the surface of the photoconductor 3 arranged above the writing unit 100, and the photosensitivity. The surface of the body 3 is exposed. Thereby, a range different from the range to be exposed based on the image information on the surface of the photoreceptor 3 is exposed, and an abnormal image is generated.
6 and 7, for the sake of convenience, hatching indicating the cross section of the scanning lens 57 is not shown for the sake of convenience, in which the path of the flare light 13a in the scanning lens 57 is indicated by an arrow.

FIG. 1 is an enlarged explanatory view of the vicinity of the scanning lens 57 and the dust-proof glass 59 of the writing unit 100 of the present embodiment. A region α surrounded by a broken line in FIG. 1 is a region through which the flare light 13a emitted from the scanning lens upper surface 57a passes when emitted from the dustproof glass 59 toward the photosensitive member 3. As shown in FIG. 1, the writing unit 100 of this embodiment includes a light shielding member 61 that blocks a part of the region α between the scanning lens upper surface 57 a and the dust-proof glass 59.
As shown in FIG. 1, flare light 13 a directed from the scanning lens 57 toward the photosensitive member 3 can be shielded by disposing a part of the light shielding member 61 between the scanning lens 57 and the dust-proof glass 59. . That is, the flare light 13 a that exits the scanning lens 57, passes through the dust-proof glass 59, exits the writing unit 100, and travels to the optical path reaching the photoreceptor 3 can be shielded.

FIG. 8 is an enlarged perspective view of the vicinity of the attachment position of the light shielding member 61 before the light shielding member 61 is attached in the writing unit 100, and FIG. 9 is a light shielding member 61 in a state where the light shielding member 61 in the writing unit 100 is attached. It is an expansion perspective view of the neighborhood.
The light shielding member 61 is a black polyester film having a thickness of about 0.1 [mm] and hardly transmits light.

  A double-sided tape 63 is used to fix the light shielding member 61 to the housing 101, and the double-sided tape 63 is affixed to the light shielding member 61 only at locations where the light shielding member 61 is affixed to the housing 101. On the housing 101 side, the upper surface of the rib 105 at a position slightly higher than the upper surface 57a of the scanning lens is used as the pasting surface 105a.

As shown in FIGS. 8 and 9, the attachment position 61a is determined using the rib 105 as the attachment reference 105b.
As shown in FIGS. 1 and 9, one end of the light shielding member 61 is fixed to the housing 101 with double-sided tape, and the other end side which is an unfixed free end is positioned to face the scanning lens upper surface 57a. Has been placed.
As shown in FIG. 9, the light shielding member 61 has a shape in which the width increases from the middle toward the free end side from the fixed end side, and the two corners 62 on the free end side scan. The arrangement is located above the lens 57.

  By making the width of the fixed portion side narrower than the free end side, the width of the rib 105 to which the light shielding member 61 is fixed can be reduced, and the rib positioned outside the path of the laser beam 13 for forming the latent image. Even if the light shielding member 61 is fixed to the 105, the increase in size of the apparatus can be suppressed. Further, by making the width on the free end side wider than that on the fixed portion side, the width on the free end side of the light shielding member 61 can be made larger than the range through which the flare light 13a passes, and the flare light 13a has a margin. Can be shielded from light.

  The latent image forming laser beam 13 is incident from the scanning lens incident surface 57d, passes through the scanning lens 57, and is emitted from the scanning lens emission surface 57b. For this reason, in the writing unit 100 of this embodiment in which the free end of the light shielding member 61 faces the scanning lens upper surface 57a, one of the light shielding members 61 is arranged in a direction orthogonal to the transmission direction of the laser light 13 through the scanning lens 57. The part is located. The light emitted in the direction orthogonal to the transmission direction of the laser light 13 is flare light 13a that does not contribute to latent image formation. Since a part of the light shielding member 61 is positioned in the emission direction, it is possible to realize a configuration in which the scanning lens upper surface 57a from which only the flare light 13a is emitted is covered with the light shielding member.

As shown in FIG. 1, the affixing surface 105a is slightly higher than the scanning lens upper surface 57a, so that the light shielding member 61 does not contact the scanning lens 57 and is slightly lifted.
The light shielding member 61 is arranged such that the scanning lens 57 is slightly lifted, and the corner 62 of the light shielding member 61 is located above the scanning lens 57. With this arrangement, even if the light-shielding member 61 is not fixed to the attachment surface 105a by the double-sided tape 63, the light-shielding member 61 includes the upper surface of the rib 105 (attachment surface 105a) and the scanning lens upper surface 57a. It is held in a state of straddling between. For this reason, it is possible to prevent the light shielding member 61 from entering between the scanning lens incident surface 57d of the scanning lens 57 and the soundproof glass 55 when the fixation is released, and shielding the laser light 13 for forming the latent image.

  Further, with the arrangement described above, even if the light shielding member 61 is deformed due to heat shrinkage or moisture absorption over time, the light shielding member 61 does not fall below the upper surface 57a of the scanning lens. For this reason, even if it fixes in a cantilever state, it can prevent shielding the laser beam 13 for latent image formation.

  Further, a flare emitted from the scanning lens upper surface 57a even when the fixed portion side of the light shielding member 61 including the corner portion 62 faces the scanning lens upper surface 57a and the free end protrudes to a position not facing the scanning lens upper surface 57a. The light 13a can be shielded. However, in this case, if the free end side of the light shielding member 61 is displaced downward toward the scanning lens 57 due to the fixation by the double-sided tape 63 or the deformation of the light shielding member 61 over time, the light shielding member 61 is free. The fixed part side of the end contacts the scanning lens upper surface 57a. At this time, the free end of the light shielding member 61 protruding to the opposite side of the fixed portion across the scanning lens 57 hangs down below the contact portion with the scanning lens upper surface 57a, and is at a position facing the scanning lens emitting surface 57b. The laser beam 13 for reaching the latent image may be shielded.

On the other hand, in this embodiment, since the free end of the light shielding member 61 including the corner portion 62 faces the scanning lens upper surface 57a, even if the free end side of the light shielding member 61 is displaced downward toward the scanning lens 57, the light shielding member. The free end 61 contacts the upper surface 57a of the scanning lens. Therefore, a part of the light shielding member 61 does not reach below the scanning lens upper surface 57a, and the light shielding member 61 can be prevented from shielding the laser light 13 for forming the latent image.
As shown in FIGS. 1 and 9, the free end of the light shielding member 61 faces the scanning lens upper surface 57a. If at least a part of the free end faces the scanning lens upper surface 57a, the other part is the scanning lens. Even if it protrudes from the upper surface 57a, it is possible to suppress light shielding when it hangs down.

The double-sided tape 63 is affixed only to the portion in contact with the housing 101. Even if foreign matter such as lint or lint adheres to the double-sided tape 63, there is no risk of blocking the laser light 13 for forming a latent image. .
In the present embodiment, a polyester film is used as the light shielding member 61, but the light shielding member 61 is not limited to this, and may be a plate-shaped resin member or a metal member.

  The scanning lens 57 of this embodiment uses a resin molded part. The optical surface (lens surface) of the scanning lens 57, that is, the scanning lens exit surface 57b and the scanning lens incident surface 57d through which the laser beam 13 passes, are required to have a highly accurate shape with few errors. On the other hand, the scanning lens upper surface 57a and the scanning lens lower surface 57c are not functionally used. For this reason, at the time of molding, the scanning lens upper surface 57a and the scanning lens lower surface 57c are cooled, and the sink marks 41 (see FIG. 6 and the like) are intentionally formed on the scanning lens upper surface 57a and the scanning lens lower surface 57c. The lens surface of the mold to be used is transferred to the molded part with high accuracy.

  Since the scanning lens upper surface 57a and the scanning lens lower surface 57c of the scanning lens 57 have sink marks as described above, their shapes vary due to molding lot differences and mold cavity differences. For this reason, the optical path of the flare light 13a transmitted or reflected through the scanning lens upper surface 57a and the scanning lens lower surface 57c becomes a cause.

  In the present embodiment, such a variation is anticipated, and a further margin is taken into consideration so that the free end side of the light shielding member 61 is larger than the range through which the flare light 13a passes. When the portion where the light shielding member 61 shields light is increased in this way, the flare light 13a is easily shielded. However, when the light shielding member 61 is unfixed, the light shielding member 61 emits the laser light 13 for forming a latent image. There is a risk of shading. On the other hand, by arranging the corner 62 of the light shielding member 61 so as to be positioned above the scanning lens 57, it is possible to prevent the latent image forming laser light 13 from being shielded. Thereby, in the writing unit 100 of this embodiment, the flare light 13a can be shielded by the light shielding member 61, and the laser light 13 for forming a latent image can be shielded.

  In the present embodiment, the light shielding member 61 is fixed to the housing 101 instead of the scanning lens 57. Thus, the influence on the scanning lens 57 is suppressed by fixing the light shielding member 61 to the housing 101 side. When the double-sided tape 63 is affixed to the scanning lens 57, the amount of elongation at the time of temperature rise differs depending on the difference in linear expansion coefficient, and thermal stress is applied to the scanning lens 57. The thermal stress applied to the scanning lens 57 affects the deformation of the lens surface and changes the scanning position on the surface of the photoreceptor 3 that is the surface to be scanned. In the color image forming apparatus, the change in the scanning position becomes a color shift from a scan position shift between colors, and the image quality deteriorates. In the present embodiment, since the light shielding member 61 is fixed on the housing 101 side, the above-described problems do not occur.

  In the present embodiment, the light shielding member 61 is fixed to the housing 101 in a cantilever structure. If fixed at both ends, the following problems may occur due to the difference in coefficient of linear expansion between the light shielding member 61 and the housing 101. That is, when thermal expansion occurs, there may be a difference between the distance between the fixed portions at both ends of the light shielding member 61 and the distance between the fixed portions in the housing 101. As described above, when a difference occurs between the distance between the fixed points and the distance between the fixed points, thermal stress is generated between the light shielding member 61 and the housing 101. When the housing 101 is deformed by this thermal stress, the position of the components of the optical system fixed to the housing 101 changes, and there is a possibility that the scanning position on the surface of the photoreceptor 3 that is the surface to be scanned changes.

In this embodiment, since the light shielding member 61 is fixed to the housing 101 in a cantilever structure, no thermal stress is generated between the light shielding member 61 and the housing 101, and the above-described problems do not occur.
In the present embodiment, the light shielding member 61 has a cantilever structure with respect to the housing 101, but it is sufficient that only one end of the light shielding member 61 is fixed to the housing 101. For example, the other end portion of the light shielding member 61 opposite to the fixed end is in contact with and supported by the scanning lens upper surface 57a or a part of the housing 101 other than the rib 105 provided with the attaching surface 105a. A structure in which the lower part of the other end is supported, such as a supported structure, may be used.

  In the multi-function device 500 including the writing unit 100 having the above-described configuration, the light shielding member 61 shields the flare light 13a, so that the flare light exposes the surface of the photoconductor 3, and thus an abnormal image such as a vertical stripe is generated. Occurrence can be prevented. Further, since no stress is generated in the housing 101 due to the provision of the light shielding member 61, it is possible to prevent the occurrence of image displacement due to the deformation of the housing 101 due to the stress.

  With the above configuration, when α in FIG. 1 is an optical path for the flare light 13a due to the surface reflection of the soundproof glass 55 to reach the photosensitive member 3, even if the optical path of the flare light 13a varies, the light shielding member 61 Can be shielded from light. Further, by fixing the light shielding member 61 to the housing 101, the fixing of the light shielding member 61 does not affect the scanning lens 57.

Furthermore, when the fixing deterioration with time or the deformation of the light shielding member 61 occurs, the corner 62 serving as the free end of the light shielding member 61 may be displaced downward, that is, displaced toward the scanning lens 57 side. Even if such a displacement occurs, in this embodiment, the corner portion 62 hits the scanning lens upper surface 57a and is not displaced further downward. Thereby, it is possible to prevent the light shielding member 61 from facing the scanning lens exit surface 57b and the scanning lens incident surface 57d, and it is possible to prevent the light shielding member 61 from shielding the laser beam 13 passing through these surfaces. Therefore, even if fixing deterioration with time or deformation of the light shielding member 61 occurs, the light shielding member 61 can shield only the flare light 13a without shielding the laser light 13 forming the latent image.
Therefore, it is possible to realize an image forming apparatus capable of outputting a high-quality image without an abnormal image due to the flare light 13a.

  In the writing unit 100 of the present embodiment, the flare light 13a reflected by the soundproof glass 55 is incident on the scanning lens 57, and then reflected internally to the width direction of the scanning lens 57 (front and back direction in FIG. 5). The light is emitted from the end portion. For this reason, the light shielding member 61 covers only the vicinity of the end portion in the width direction of the scanning lens upper surface 57a. When the flare light 13a is emitted from the vicinity of the center of the scanning lens 57 in the width direction, the length of the light shielding member 61 is increased to cover the vicinity of the center of the scanning lens 57 in the width direction, or scanning. It is good also as a structure which covers the whole area of the width direction of the lens 57. FIG.

In the above-described embodiment, the case where the optical system constituent member that emits the flare light 13a shielded by the light shielding member 61 is the scanning lens 57 that is an imaging optical element has been described. The optical system constituent member that emits the flare light 13a shielded by the light shielding member 61 is not limited to the scanning lens. Any member that forms an optical system, such as various lenses and mirrors, may be used as long as it emits light (flare light) that travels along a path different from the predetermined path.
In the above-described embodiment, the outline of the tandem color image forming apparatus is shown. However, the image forming apparatus is not limited to the tandem color image forming apparatus, and is effective in a monochrome image forming apparatus.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect A)
An optical system constituent member such as a scanning lens 57 that constitutes a part of an optical system through which a light beam such as laser light 13 passes, a holder such as a housing 101 that holds the optical system, and light emitted from the optical system constituent member Among them, in an optical scanning apparatus such as a writing unit 100 having a light shielding member such as a light shielding member 61 that shields light such as flare light 13a directed to a path different from a predetermined path, only one end of the light shielding member is held. Secure against the body.
According to this, as described in the above embodiment, by fixing only one end of the light shielding member to the holding body, a difference in expansion amount during thermal expansion occurs between the light shielding member and the holding body. However, no stress acts on the holder. For this reason, it can prevent that a stress acts on a holding body resulting from providing a light shielding member in an optical scanning device.

(Aspect B)
In aspect A, a dust-proof glass that is made of a cover member such as an upper cover 102 that covers a holding body such as the housing 101 and a material through which a light beam such as a laser beam 13 transmits, and that blocks an opening provided on the cover member through which the light beam passes. And a part of the light shielding member such as the light shielding member 61 is located between the optical system constituent member such as the scanning lens 57 and the opening light transmissive member.
According to this, as described in the above embodiment, the optical system constituent member is emitted and transmitted through the aperture light transmitting member, and is emitted to the outside of the optical scanning device such as the writing unit 100 and the like. It is possible to block light such as flare light 13a toward the optical path reaching the irradiation target.

(Aspect C)
In either aspect A or B, a part of the light-shielding member such as the light-shielding member 61 is opposed to the optical system constituent member such as the scanning lens 57.
According to this, as described in the above embodiment, the light to be shielded such as the flare light 13a emitted from the position facing the light shielding member in the optical system constituent member can be shielded. In addition, even if fixing deterioration with time or deformation of the light shielding member occurs, the light shielding member hits the optical system component member, and the surface other than the surface that emits light to be shielded on the surface of the optical system component member is shielded. It can prevent that a member opposes. Thereby, it is possible to prevent light passing through a surface other than the surface from which light to be shielded is emitted from being shielded by the light shielding member.

(Aspect D)
In any one of the aspects A to C, at least a part (corner part 62 or the like) of the free end of the cantilever structure of the light shielding member such as the light shielding member 61 faces the optical system constituent member such as the scanning lens 57.
According to this, as described in the above embodiment, even if the light shielding member is displaced toward the optical system constituent member, the light shielding member shields the light beam such as the laser beam 13 for forming the latent image. The side effect resulting from providing a member can be suppressed.

(Aspect E)
In any of the aspects A to D, the optical system constituent member is a light transmitting member such as the scanning lens 57 through which the light beam such as the laser beam 13 is transmitted, and is orthogonal to the light transmission direction of the light transmitting member. A part of the light shielding member such as the light shielding member 61 is located in the direction (upward direction).
According to this, as described in the above embodiment, the configuration in which the light shielding member covers the surface that emits only the light to be shielded such as the flare light 13a that does not contribute to the latent image formation in the optical transmission member is realized. Can do.

(Aspect F)
In any one of the aspects A to E, the fixing portion (the pasting surface 105a or the like) of the light shielding member such as the light shielding member 61 or the like with respect to the holding body such as the housing 101 or the like is higher than the upper surface of the optical system constituent member such as the scanning lens 57. Above, a part of the light shielding member faces the upper surface of the optical system constituent member.
According to this, as described in the above embodiment, it is possible to realize a configuration in which the light shielding member is arranged so as to cover the upper surface of the optical system constituent member.

(Aspect G)
In any of the aspects A to F, the light shielding member such as the light shielding member 61 shields light to be shielded such as the flare light 13a from the part fixed to the holding body such as the housing 101 ( The vicinity of the corner 62 is a wider shape.
According to this, as described in the above embodiment, the light to be shielded that does not contribute to the formation of the latent image can be shielded with a margin while suppressing the enlargement of the apparatus.

(Aspect H)
In any of the aspects A to G, the light shielding member such as the light shielding member 61 is fixed by an adhesive tape such as the double-sided tape 63, and the adhesive tape is a portion where the light shielding member shields light to be shielded such as flare light 13a. It is pasted only on a part other than.
According to this, as described in the above embodiment, it is possible to suppress the side effect that the foreign matter blocks the light beam such as the laser beam 13 for forming a latent image even if the adhesive tape has a foreign matter.

(Aspect I)
It was obtained by irradiating the surface of a latent image carrier such as the photosensitive member 3 with a light beam such as a laser beam 13 using an optical scanning means to form a latent image on the surface of the latent image carrier and developing the latent image. In an image forming apparatus such as a multi-function device 500 that forms an image by finally transferring an image onto a recording material such as transfer paper S, the writing according to any one of aspects A to H is used as an optical scanning unit. An optical scanning device such as the unit 100 is used.
According to this, as described in the above embodiment, generation of abnormal images due to exposure of light to be shielded such as flare light 13a that does not contribute to latent image formation to the surface of the latent image carrier is prevented. it can. Furthermore, it is possible to prevent the occurrence of image misalignment due to the provision of the light shielding member. Therefore, a high quality image can be obtained.

DESCRIPTION OF SYMBOLS 1 Image forming device 2 Charging device 3 Photoconductor 5 Developing device 6 Primary transfer roller 7 Cleaning device 8 Paper discharge tray 9 Fixing device 10 Paper feed cassette 11 Paper feed roller 12 Registration roller pair 13 Laser light 13a Flare light 15 Developing roller 16 Intermediate Transfer belt 18 Paper discharge roller 20 Toner bottle 26 Secondary transfer roller 31 Contact glass 32 First traveling body 32a Original illumination light source 32b First mirror 33 Lens 35 Second traveling body 35a Second mirror 35b Third mirror 41 Sink 51 Light source 52 Coupling lens 53 Aperture 54 Cylindrical lens 55 Soundproof glass 56 Polygon scanner 57 Scanning lens 57a Scanning lens upper surface 57b Scanning lens exit surface 57c Scanning lens lower surface 57d Scanning lens entrance surface 59 Dustproof glass 61 Light shielding member 61a Pasting position 62 Angle 63 Double-sided tape 80 First reflecting mirror 81 Second reflecting mirror 100 Writing unit 101 Housing 102 Upper cover 103 Lower cover 105 Rib 105a Adhering surface 105b Adhering reference 200 Image forming unit 300 Reading unit 400 Paper feeding unit 500 Multifunction device S Transfer paper

Japanese Patent No. 4925623

Claims (9)

An optical system component that forms part of the optical system through which the light passes; and
A holder for holding the optical system;
A light-blocking member that blocks light traveling from a path different from a predetermined path among the light emitted from the optical system constituent member;
An optical scanning device, wherein only one end of the light shielding member is fixed to the holding body. The optical scanning device according to claim 1.
A cover member covering the holding body;
An opening light transmitting member that is made of a material that transmits light, and that covers the opening through which the light beam provided in the cover member passes,
A part of the light shielding member is located between the optical system constituting member and the opening light transmitting member. The optical scanning device according to claim 1,
An optical scanning device characterized in that a part of the light shielding member opposes in the vicinity of the optical system constituent member. The optical scanning device according to any one of claims 1 to 3,
An optical scanning device characterized in that at least a part of a free end of the cantilever structure of the light shielding member faces the optical system constituent member. In the optical scanning device according to any one of claims 1 to 4,
The optical system constituent member is a light transmitting member that transmits light,
An optical scanning device characterized in that a part of the light shielding member is positioned in a direction orthogonal to a light transmission direction of the light transmitting member. The optical scanning device according to claim 1,
An optical scanning device characterized in that the light shielding member is fixed to the holder above the upper surface of the optical system constituent member, and a part of the light shielding member faces the upper surface of the optical system constituent member. . The optical scanning device according to any one of claims 1 to 6,
The light scanning device according to claim 1, wherein the light shielding member has a wider shape in a portion that shields light than a portion fixed to the holding body. The optical scanning device according to any one of claims 1 to 7,
The optical scanning device, wherein the light shielding member is fixed with an adhesive tape, and the adhesive tape is attached only to a part other than a portion where the light shielding member shields light. The surface of the latent image carrier is irradiated with light using an optical scanning means to form a latent image on the surface of the latent image carrier, and an image obtained by developing the latent image is finally formed on a recording material. In an image forming apparatus that forms an image by transferring,
An image forming apparatus using the optical scanning device according to claim 1 as the optical scanning unit.

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