JP2019128485A - Optical scanner and image forming apparatus including the same - Google Patents

Abstract

To provide an optical scanner that detects a deflected and scanned beam by a beam detection unit, the optical scanner capable of effectively preventing a beam made incident to the beam detection unit from being blocked by dust, and an image forming apparatus including the optical scanner.SOLUTION: An optical scanner comprises: a deflector that deflects and scans a beam; an fθ lens through which a beam passes which is deflected and scanned by the deflector and directed toward a surface to be scanned; a lens for beam detection that is provided outside a range of an effective beam scan area; a beam detection unit that detects the beam from the lens for beam detection at the outside of the effective scan area; and a blocking member that blocks a gap between the fθ lens and a lens for beam detection.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an optical scanning device that detects a beam that has been deflected and scanned by a beam detection unit, and an image forming apparatus such as a copying machine, a multifunction peripheral, a printer, or a facsimile machine provided with the same.

  As an optical scanning device for detecting a deflected and scanned beam by a beam detection unit, for example, there is the one described in Patent Document 1.

  That is, Patent Document 1 discloses a light sensor (beam detection unit, for example, a BD sensor, for example, a BD sensor) serving as a synchronous detection element for the light beam (beam) deflected by the light deflector via an imaging lens (beam detection lens, for example, a BD lens) Discloses the configuration leading to the

  By the way, in the optical scanning device, when dust enters inside and dust adheres to the lens system member, an image formed is affected. In this case, the inconvenience is eliminated by cleaning the lens system members. However, if the beam incident on the beam detection unit is blocked by dust, a beam detection error may occur and image formation itself can not be performed. Therefore, it is required to prevent the beam incident on the beam detection unit from being blocked by dust.

  In this regard, the configuration described in Patent Document 1 is not configured to prevent the beam incident on the beam detection unit from being blocked by dust.

JP 2004-333556 A

  Therefore, the present invention is an optical scanning device that detects a deflected and scanned beam by a beam detection unit, and is capable of effectively preventing the beam incident on the beam detection unit from being blocked by dust. An object of the present invention is to provide an image forming apparatus provided with the same.

  In order to solve the above problems, an optical scanning device according to the present invention comprises: a deflector for deflecting and scanning a beam; an fθ lens through which the beam is deflected and scanned by the deflector and travels to a surface to be scanned; A beam detection lens provided outside the range of the effective scanning area of the beam; a beam detection unit for detecting the beam from the beam detection lens outside the range of the effective scanning area; the fθ lens and the beam detection And a closing member for closing between the lenses.

  According to the present invention, it is possible to effectively prevent the beam incident on the beam detection unit from being blocked by dust.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus including an optical scanning device according to an embodiment of the present invention as viewed from the front. FIG. 2 is a perspective view of an optical scanning device and a surface to be scanned as viewed from diagonally above the front side. It is a perspective view which shows the state which removed the 2nd housing | casing of the optical scanning device. FIG. 4 is a perspective view of the optical scanning device shown in FIG. 3 as viewed obliquely from above on the left side. It is the perspective view which looked at the optical scanning device shown in FIG. 3 from diagonally upward on the front side. It is a perspective view which shows the closing member part shown in FIG. It is a top view which shows the closing member part in an optical scanner. It is a top view which shows the substrate part which mounts a light source and a beam detection part. It is a top view which shows a mode that the board | substrate was removed in FIG. It is a rear view which shows the 1st housing | casing which removed the board | substrate which mounted the light source and the beam detection part.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[Image forming apparatus]
FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 including an optical scanning device 200 according to an embodiment of the present invention as viewed from the front. Image forming apparatus 100 according to the present embodiment is a monochrome image forming apparatus. The image forming apparatus 100 performs an image forming process in accordance with the image data read by the image reading apparatus 1 or the image data transmitted from the outside. The image forming apparatus 100 may be a color image forming apparatus that forms a multi-color image and a single-color image on the sheet P.

  The image forming apparatus 100 includes a document feeder 108 and an image forming apparatus main body 110. The image forming apparatus main body 110 is provided with an image forming unit 102 and a sheet conveyance system 103.

  The image forming unit 102 includes an optical scanning device 200 (specifically, an optical scanning unit), a developing unit 2, a photosensitive drum 3 that acts as an electrostatic latent image carrier, a cleaning unit 4, a charging device 5, and a fixing unit 7. I have. These constituent members are supported by the main body frame 101 of the image forming apparatus 100. The sheet conveyance system 103 also includes a sheet feed tray 81, a manual sheet feed tray 82, an ejection roller 31, and an ejection tray 14.

  At the upper part of the image forming apparatus main body 110, an image reading apparatus 1 for reading an image of a document G is provided. The image reading apparatus 1 includes a document placement table 107 on which a document G is placed. The document table 107 is in the shape of a square made of transparent tempered glass. Further, a document feeding device 108 is provided above the document placement table 107. In the image forming apparatus 100, the image of the document G read by the image reading apparatus 1 is sent to the image forming apparatus main body 110 as image data, and the image is recorded on the sheet P.

  The image forming apparatus main body 110 is provided with a sheet conveyance path W1. The sheet feeding tray 81 or the manual sheet feeding tray 82 supplies the sheet P to the sheet conveyance path W1. The sheet conveyance path W1 guides the sheet P to the discharge tray 14 through the transfer roller 10 and the fixing unit 7. The fixing unit 7 heats and fixes the toner image formed on the sheet P to the sheet P. In the vicinity of the sheet conveyance path W1, pickup rollers 11a and 11b, a conveyance roller 12a, a registration roller 13, a transfer roller 10, a heat roller 71 and a pressure roller 72 in the fixing unit 7, and a discharge roller 31 are disposed.

  In the image forming apparatus 100, the sheet P supplied by the sheet feeding tray 81 or the manual sheet feeding tray 82 is conveyed to the registration roller 13. Next, the sheet P is conveyed to the transfer roller 10 at a timing at which the sheet P and the toner image on the photosensitive drum 3 are aligned by the registration roller 13. The toner image on the photosensitive drum 3 is transferred onto the sheet P by the transfer roller 10. Thereafter, the sheet P passes through the heat roller 71 and the pressure roller 72 in the fixing unit 7, and is discharged onto the discharge tray 14 through the conveyance roller 12 a and the discharge roller 31. When image formation is performed not only on the front surface of the paper P but also on the back surface, the paper P is transported in the reverse direction from the discharge roller 31 to the reverse paper transport path W2. The sheet P passes through the reverse conveying rollers 12b to 12b, and is turned over to the registration roller 13 after the sheet P is reversed. The paper P is discharged onto the discharge tray 14 after a toner image is formed and fixed on the rear surface in the same manner as the front surface.

[Optical scanning device]
FIG. 2 is a perspective view of the light scanning device 200 and the surface to be scanned F as viewed from diagonally above the front side. FIG. 3 is a perspective view showing a state in which the second housing 202 of the light scanning device 200 is removed. In the figure, reference numeral X denotes the main scanning direction (in this example, the depth direction), reference numerals X1 and X2 denote one side (rear side) and the other side (front side). The symbol Y represents a sub-scanning direction (vertical direction, vertical direction in this example) orthogonal to the main scanning direction X. The code Z is an orthogonal direction orthogonal to both the main scanning direction X and the sub-scanning direction Y (horizontal direction when viewed from the front of this example), and symbols Z1 and Z2 are one side (right side when viewed from the front) From left to right).

  The optical scanning device 200 includes an incident optical system 220, a deflector 230, an output optical system 240, and a detection unit 250. The incident optical system 220 is disposed upstream of the deflector 230 in the traveling direction of the beam BM. The incident optical system 220 causes the beam BM to be incident on the deflector 230. The deflector 230 deflects and scans the beam BM in the main scanning direction X. The emission optical system 240 is disposed between the deflector 230 and the surface to be scanned F (in this example, the surface of the photosensitive drum 3) on the optical path of the beam BM. The emission optical system 240 irradiates the beam BM deflected and scanned by the deflector 230 onto the surface F to be scanned. The detector 250 detects the beam BM deflected and scanned by the deflector 230. The entrance optical system 220, the deflector 230, the exit optical system 240, and the detection unit 250 are accommodated in the first housing 201 (an example of the housing).

  In the optical scanning device 200, the beam BM from the incident optical system 220 is incident on the deflector 230, is deflected and scanned in the main scanning direction X by the deflector 230, and is detected by the detector 250 via the output optical system 240. Then, image information is written on the surface F of the photosensitive drum 3 to be scanned. The beam BM periodically scans the surface to be scanned F in the main scanning direction X. However, since the photosensitive drum 3 rotates in the rotation direction B (see FIG. 2), the secondary surface on the photosensitive drum 3 is rotated. It is also possible to scan in the scanning direction Y.

(Incidence optical system)
The incident optical system 220 irradiates the beam BM to the reflecting surface 231 a of the deflector 230. The incident optical system 220 includes a light source unit 210, a collimator lens 221, an aperture member 222, and a cylindrical lens 223.

  The light source unit 210 includes a light source 211. The light source 211 is formed of a semiconductor laser element such as a laser diode that emits a beam BM. The light source 211 emits a beam BM modulated according to image data. The light source 211 emits a beam BM having a circular beam cross section perpendicular to the optical axis. The light source 211 is mounted on the substrate 260.

  The collimator lens 221 is an optical component that shapes the beam BM emitted from the light source 211 in parallel. The aperture member 222 is a plate-like member in which a slit-like opening 222 a long in the main scanning direction X is formed. The aperture member 222 is an optical component that shapes the beam cross section into a rectangular shape when the beam BM from the collimator lens 221 passes. The cylindrical lens 223 is an optical component that causes the beam BM from the aperture member 222 to converge toward the reflecting surface 231 a of the deflector 230.

(Deflector)
In this example, the deflector 230 includes a polygon mirror 231 (a rotating polygon mirror) and a drive motor 232 that rotationally drives the polygon mirror 231. The polygon mirror 231 is fixed to the rotation shaft 232 a of the drive motor 232. The polygon mirror 231 has a plurality of reflecting surfaces 231a along the rotation axis 232a at the periphery. The drive motor 232 rotates at a constant rotational speed in a constant rotational direction E. Thus, the polygon mirror 231 can deflect and scan the beam BM incident on the reflecting surface 231 a in the main scanning direction X.

(Reflective optical system)
The emission optical system 240 irradiates the beams BM, which are repeatedly scanned in the main scanning direction X, on the surfaces to be scanned F to F. The emission optical system 240 includes an fθ lens 241. The lens 230 is deflected for scanning by the deflector 230 and passes the beam BM directed to the surface F to be scanned. The fθ lens 241 is formed in a rod shape elongated in the main scanning direction X.

  The fθ lens 241 has a function of correcting the beam BM emitted from the reflecting surface 231a of the deflector 230 and moving at a constant angular velocity so that the beam BM moves on the scanned surface F at a constant velocity. Further, the fθ lens 241 has a function of causing the beam BM to converge on the surface to be scanned F.

(Detection unit)
The detection unit 250 includes a beam detection lens 251 and a beam detection unit 252 (specifically, a semiconductor light sensor). The beam detection lens 251 has a function of bending the beam BM reflected by the reflection surface 231 a of the deflector 230 and passing through the fθ lens 241 toward the beam detection unit 252. Also, the beam detection lens 251 has a function of focusing the beam BM on the beam detection unit 252. The beam detection unit 252 detects the beam BM from the beam detection lens 251 outside the range of the effective scanning area α. The effective scanning area α of the beam BM is an area where the beam BM irradiates the surface F to be scanned, and is a scanning area used as an image forming width for actually forming an image. The beam detection unit 252 photoelectrically converts the beam BM collected by the beam detection lens 251. In this example, the beam detection unit 252 is a beam detection (BD: Beam Detect) sensor for controlling the scanning timing of the beam BM (specifically, the writing timing of the image on the surface F to be scanned).

  Specifically, the detection unit 250 is disposed outside the range of the effective scanning area α on the surface to be scanned F. The beam detection lens 251 is disposed on the optical path of the beam BM outside the range of the effective scanning area α. The beam detection unit 252 receives the beam BM from the beam detection lens 251. The beam detection unit 252 is mounted on the substrate 260.

(Housing)
The first housing 201 is provided with an opening 201a for emitting the beam BM deflected and scanned by the deflector 230 in the effective scanning area α. In this example, the opening 201a is open to the outside. Accordingly, in the optical scanning device 200, air from the outside is circulated from the opening 201a to the inside. Then, in the optical scanning device 200, dust tends to get inside. When dust adheres to the lens system member, the formed image is likely to be affected. In this case, the inconvenience is eliminated by cleaning the lens system members. However, if the beam BM incident on the beam detection unit 252 is blocked by dust, a beam detection error may occur and image formation itself can not be performed. Therefore, it is required to prevent the beam BM incident on the beam detector 252 from being blocked by dust.

  By the way, dust which is caused to flow by the flow of air in the optical scanning device 200 is likely to be accumulated at corners (particularly at acute corners) or in gaps. In the area through which the beam BM incident on the beam detection unit 252 passes, the portion where dust tends to accumulate is a corner (in particular, an acute corner) or a gap formed by the fθ lens 241 and the beam detection lens 251. . In addition, stray light may be generated in the beam detection lens 251. In this case, stray light from the beam detection lens 251 enters the effective scanning area α. This affects the image caused by stray light in the beam detection lens 251.

First Embodiment
From this point of view, the optical scanning device 200 according to the present embodiment includes a blocking member 270 that blocks between the fθ lens 241 and the beam detection lens 251. The closing member 270 closes a corner (a sharp corner in this example) or a gap formed by the fθ lens 241 and the beam detection lens 251.

  FIG. 4 is a perspective view of the optical scanning device 200 shown in FIG. 3 as viewed obliquely from above on the left side. FIG. 5 is a perspective view of the light scanning device 200 shown in FIG. 3 as viewed obliquely from above on the front side. 6 is a perspective view showing the closing member 270 shown in FIG. FIG. 7 is a plan view showing a closing member 270 portion in the optical scanning device 200. FIG.

  According to the present embodiment, the blocking member 270 blocks between the fθ lens 241 and the beam detection lens 251. Therefore, it is possible to suppress dust accumulation in the corner or gap where dust is likely to be accumulated in the area through which the beam BM incident on the beam detection unit 252 passes. Thereby, it can be effectively prevented that the beam BM incident on the beam detection unit 252 is blocked by dust. In addition, the blocking member 270 can suppress entry of stray light by the beam detection lens 251 into the effective scanning area α. Therefore, the influence of the image due to stray light on the beam detection lens 251 can be reduced. Here, the blocking member 270 can be formed of an opaque material or a material whose light transmittance is smaller than a predetermined value, from the viewpoint of light shielding property against stray light. In addition, the blocking member 270 can be formed of a material which does not reflect light or whose light reflectance is smaller than a predetermined value. In this example, the closing member 270 is formed of a black material.

  By the way, when the blocking member 270 blocks the beam passage area β through which the beam BM passes between the fθ lens 241 and the beam detection lens 251, a beam detection error occurs and the image formation itself can not be performed. On the other hand, if the blocking member 270 blocks the effective scanning area α, it affects the formed image.

  In this regard, in the present embodiment, the blocking member 270 is a partition portion that divides the beam passage area β and the effective scanning area α. By doing this, dust does not block the beam passing area β and the effective scanning area α, and dust in the corner or gap where dust is likely to be accumulated in the area through which the beam BM incident on the beam detection unit 252 passes. Can be suppressed.

  In the present embodiment, the closing member 270 is configured by a sheet-like member. In this way, it is possible to suppress dust accumulation in corner portions or gaps where dust easily accumulates in the area through which the beam BM incident on the beam detection unit 252 passes, with a simple and inexpensive configuration. In this example, the closing member 270 is a sheet-like member (elastic resin film) made of resin.

  In the present embodiment, the beam detection lens 251 has a flat portion 251a. A closing member 270 formed of a sheet-like member is provided (specifically, adhered) to the flat portion 251 a of the beam detection lens 251. By doing so, it is not necessary to separately provide a configuration for providing the closing member 270. Thereby, the closing member 270 can be provided in a state where space saving is realized. Specifically, the flat portion 251a is located in a portion where the beam BM does not pass.

  In the present embodiment, the blocking member 270 extends to the opposite side of the fθ lens 241 with respect to the beam detection lens 251. In this way, the blocking member 270 can further suppress the entry of stray light at the beam detection lens 251 into the effective scanning area α. Therefore, the influence of the image due to stray light on the beam detection lens 251 can be further reduced or eliminated. In this example, the blocking member 270 extends along the flat portion 251 a opposite to the deflector 230.

  Specifically, an outer peripheral side wall 201 e is provided on the outer peripheral portion of the first housing 201. The blocking member 270 may be extended so as to be close to or in contact with the outer circumferential inner wall surface 201 f of the outer circumferential side wall 201 e without blocking the effective scanning region α.

Second Embodiment
In the present embodiment, the beam detection lens 251 is a prism lens. By doing so, the traveling direction of the beam BM from the deflector 230 can be bent by the beam detection lens 251 which is a prism lens. Thus, the beam detection unit 252 can be disposed at a desired position for miniaturizing the light scanning device 200. Therefore, the miniaturization of the optical scanning device 200 can be easily realized.

  FIG. 8 is a plan view showing a portion of the substrate 260 on which the light source 211 and the beam detector 252 are mounted. FIG. 9 is a plan view showing a state where the substrate 260 is removed from FIG. FIG. 10 is a rear view showing the first housing 201 from which the substrate 260 on which the light source 211 and the beam detection unit 252 are mounted is removed.

Third Embodiment
In the present embodiment, a first housing 201, a light source 211, and a substrate 260 are further provided. In the first housing 201, a deflector 230, an fθ lens 241, a beam detection lens 251, and a beam detection unit 252 are provided. The substrate 260 mounts the light source 211 and the beam detection unit 252 on the same substrate surface 261. By doing this, the substrate for the light source and the substrate for the beam detection unit can be shared by one substrate. Thereby, cost reduction can be realized. Further, the first housing 201 is provided with a light source opening 201 b and a beam detection opening 201 c. The light source opening 201 b passes the beam BM emitted from the light source 211. The beam detection opening 201 c passes the beam BM incident on the beam detection unit 252. The substrate 260 is provided in the first housing 201 from the outside of the first housing 201 so that the light source 211 faces the light source opening 201 b and the beam detection unit 252 faces the beam detection opening 201 c. . By this, the space for providing the substrate in the first housing 201 can be reduced. Thereby, further miniaturization of the optical scanning device can be realized.

  Specifically, the first housing 201 accommodates the collimator lens 221, the aperture member 222, the cylindrical lens 223, the deflector 230, the fθ lens 241, and the beam detection lens 251. The light source opening 201b and the beam detection opening 201c are provided on the outer peripheral side wall 201e. The substrate 260 is provided so that the mounting side of the light source 211 and the beam detection unit 252 faces the outer peripheral side wall 201e of the first housing 201. The light source 211 is located in the light source opening 201b, and the beam detection unit 252 is located in the beam detection opening 201c. Thus, the beam BM from the light source 211 can be emitted toward the collimator lens 221. Further, the beam BM from the beam detection lens 251 can be incident on the beam detection unit 252.

  In the present embodiment, the closing member 270 is in contact with the fθ lens 241 and the beam detection lens 251. By doing this, it is possible to reliably suppress dust accumulation in corner portions or gaps where dust is easily accumulated in the area through which the beam BM incident on the beam detection unit 252 passes. In addition, the influence of the image due to stray light on the beam detection lens 251 can be further reduced. In this case, the closing member 270 may be brought into contact with or close to the bottom surface 201d of the first housing 201. Further, the closing member 270 may be brought into contact with or close to the second housing 202 (upper lid).

(Other embodiments)
In the present embodiment, the closing member 270 may be configured by a rib standing from the bottom surface 201 d of the first housing 201. By doing this, the closing member 270 can be stably held on the bottom surface 201 d of the first housing 201. Therefore, it is possible to reliably suppress dust accumulation in corners or gaps where dust in the region through which the beam BM incident on the beam detection unit 252 passes is likely to accumulate. Moreover, the influence of the stray light at the beam detection lens 251 can further reduce the influence of the image. In this case, the closing member 270 can be brought close to the fθ lens 241 and the beam detection lens 251. Also, the closing member 270 may be brought into contact with or in proximity to the second housing 202 so as to face it. Further, the closing member 270 may be configured by a rib standing from the bottom surface of the second housing 202. In this case, the closing member 270 can be brought close to and opposed to the fθ lens 241 and the beam detection lens 251. Further, the closing member 270 may be in contact with or close to the bottom surface 201 d of the first housing 201. In addition, the closing member 270 may be provided in the fθ lens 241. In addition, a transparent plate such as glass may be provided in the opening 201 a of the first housing 201 to close the opening 201 a.

  The present invention is not limited to the embodiments described above, and can be implemented in other various forms. Therefore, such an embodiment is merely illustrative in every point and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of the claims, and is not limited at all by the text of the specification. Furthermore, all variations and modifications that fall within the equivalent scope of the claims fall within the scope of the present invention.

100 Image Forming Device 200 Optical Scanning Device 201 First Case (Example of Case)
201a opening 201b light source opening 201c beam detection opening 201d bottom surface 201e outer peripheral side wall 202 second housing 210 light source unit 211 light source 220 incident optical system 221 collimator lens 222 aperture member 223 cylindrical lens 230 deflector 231 polygon mirror 240 emission optical system 241 fθ lens 250 detection unit 251 beam detection lens 251a flat portion 252 beam detection unit 260 substrate 261 substrate surface 270 closing member B rotation direction BM beam E rotation direction F scan surface X main scan direction Y sub scan direction α effective scan area β Beam passing area

Claims (9)

A deflector for deflecting and scanning the beam;
An fθ lens through which the beam is deflected and scanned by the deflector and directed to the surface to be scanned;
A beam detection lens provided outside the effective scanning area of the beam;
A beam detection unit for detecting the beam from the beam detection lens outside the range of the effective scanning area;
An optical scanning device comprising: a closing member for closing between the fθ lens and the beam detection lens. The optical scanning device according to claim 1,
The optical scanning device according to claim 1, wherein the closing member is a partition part between the fθ lens and the beam detection lens and a beam passing area through which the beam passes and the effective scanning area. The optical scanning device according to claim 1 or 2, wherein
The light blocking device is characterized in that the closing member is a sheet-like member. The optical scanning device according to claim 3,
The beam scanning lens has a flat portion, and the blocking member made of the sheet-like member is provided on the flat portion. The optical scanning device according to any one of claims 1 to 4, wherein
The optical scanning device according to claim 1, wherein the blocking member extends on the opposite side to the fθ lens with respect to the beam detection lens. The optical scanning device according to any one of claims 1 to 5, wherein
The light scanning device according to claim 1, wherein the beam detection lens is a prism lens. The optical scanning device according to claim 6, wherein
A housing provided with the deflector, the fθ lens, the beam detection lens, and the beam detection unit;
A light source for emitting the beam;
And a substrate for mounting the light source and the beam detection unit on the same substrate surface,
The housing is provided with a light source opening through which the beam emitted from the light source passes and a beam detection opening through which the beam incident on the beam detector is passed,
The substrate is provided on the casing from the outside of the casing such that the light source faces the light source opening, and the beam detection unit faces the beam detection opening. Optical scanning device. The optical scanning device according to any one of claims 1 to 7, wherein
The optical scanning device, wherein the closing member is in contact with the fθ lens and the beam detection lens.   An image forming apparatus comprising the light scanning device according to any one of claims 1 to 8.

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