Optical scanner and image formation device including the same

Abstract

To provide an optical scanner in which detection accuracy is not reduced when a transmission type detection part is used and with which a smooth movement of a cleaning holder can be maintained, and provide an image formation device including the optical scanner.SOLUTION: An optical scanner includes a housing, a transmissive member, a linear member, a drive part, a guide rail, a cleaning holder, a cleaning member, a detection part, and a control part. The detection part includes: a light emission part that emits light in a parallel direction of the transmissive member; and a light reception part that receives light emitted from the light emission part. The detection part is arranged along the housing such that a longitudinal direction of the light emission part and the light reception part is parallel to a movement direction of the cleaning holder. The cleaning holder has a light shielding part that is arranged between the light emission part and the light reception part and shields light emitted from the light emission part when reaching one end portion of a movement route. A gap is formed between the light shielding part and the housing. The housing is formed with a light leakage prevention part between the light emission part and the light reception part.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to an optical scanning device that irradiates a photosensitive member with light to form an electrostatic latent image in an electrophotographic image forming apparatus, and an image forming apparatus including the optical scanning device.

Background Art

[0002] A conventional optical scanning device is disclosed in Patent Document 1. This optical scanning device irradiates a charged photosensitive member with light to form an electrostatic latent image on the photosensitive member. The optical scanning device includes a housing, a transmissive member, a linear member, a drive member, a guide rail, a cleaning holder, a cleaning member, and a stopper.

[0003] The housing is formed with an exit port for laser light that extends in the main scanning direction of the laser light irradiated on the photosensitive member. The transmissive member extends in the main scanning direction of the laser light and seals the exit port of the laser light. The spiral member extends in the extending direction of the transmissive member. The guide rail is arranged in parallel with the exit port and extends in the extending direction of the transmissive member.

[0004] The cleaning holder is connected to the linear member, and two cleaning holders move along the transmissive member as the linear member runs in a loop. The cleaning member is fixed to the cleaning holder and cleans the transmissive member by sliding with respect to the transmissive member as the cleaning holder moves. The cleaning holder abuts against the stopper at one end of the movement path, thereby stopping the running of the linear member.

[0005] In the configuration of Patent Document 1, at the time of switching from the forward movement operation to the return movement operation, it is stopped in a state of being in contact with the stopper. At this time, a large tension (load) is applied to the linear member, and there is a problem that the gear that supports the linear member so as to be able to run in a loop is damaged. Therefore, a method of detecting the position of the cleaning holder using a transmissive optical sensor (photo interrupter) in which a light emitting part and a light receiving part are arranged opposite to each other can be considered.

[0006] In the case of a transmissive optical sensor, as described in Patent Documents 2 to 4, it is common to use it in a state where the optical path between the light emitting part and the light receiving part can be completely blocked by a light shielding member. When there is a wall surface (frame) parallel to the opposing direction of the light emitting part and the light receiving part near the sensor, if the optical path between the light emitting part and the light receiving part is not completely blocked by the light shielding member, the light emitted from the light emitting part is reflected by the wall surface, and the reflected light enters the light receiving part, resulting in a decrease in detection accuracy.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] When detecting the position of the cleaning holder using a transmissive optical sensor, since there is a housing (frame) of the optical scanning device below the optical sensor, there is a possibility that the light passing through the gap between the light shielding member provided on the cleaning holder and the housing enters the light receiving part, resulting in a decrease in detection accuracy. On the other hand, when the gap between the light shielding member and the housing is eliminated, there is a problem that the friction between the cleaning holder and the housing increases, and the cleaning holder cannot move smoothly.

[0009] In view of the above problems, an object of the present invention is to provide an optical scanning device that does not reduce the detection accuracy when using a transmissive detection unit and can maintain smooth movement of the cleaning holder, and an image forming apparatus including the same.

Means for Solving the Problems

[0010] In order to achieve the above object, a first configuration of the present invention includes a housing, a transmissive member, a linear member, a driving unit, a guide rail, a cleaning holder, a cleaning member, a detection unit, and a control unit, and is an optical scanning device that irradiates a laser beam onto an image carrier to form an electrostatic latent image. The housing is formed with an exit port for the laser beam that extends in the main scanning direction of the laser beam corresponding to the image carrier. The transmissive member has transmissivity to the laser beam, extends in the main scanning direction of the laser beam, and seals the exit port of the laser beam. The linear member is stretched annularly around the housing. The driving unit runs the linear member in a predetermined direction. The guide rail is arranged in parallel with the exit port and extends in the extending direction of the transmissive member. The cleaning holder is fixed to the linear member and moves on the transmissive member along the guide rail when the linear member is run by the driving unit. The cleaning member is fixed to the cleaning holder and cleans the transmissive member by sliding with respect to the transmissive member as the cleaning holder moves. The detection unit is arranged on one side in the extending direction of the transmissive member and detects that the cleaning holder has reached one end of the moving path of the cleaning holder. The control unit controls the driving of the driving unit. The detection unit has a light emitting unit that emits light in the parallel direction of the transmissive member and a light receiving unit that receives the light emitted from the light emitting unit, and is arranged along the housing such that the longitudinal direction of the light emitting unit and the light receiving unit is parallel to the moving direction of the cleaning holder. The cleaning holder has a light shielding portion that is arranged between the light emitting unit and the light receiving unit when reaching one end of the moving path and shields the light emitted from the light emitting unit, and a gap is formed between the light shielding portion and the housing. The housing is formed with a light leakage prevention portion between the light emitting unit and the light receiving unit.

Effect of the Invention

[0011] According to the first configuration of the present invention, by forming a light leakage prevention portion in the portion facing the space between the light emitting unit and the light receiving unit of the housing, it is possible to prevent the light reflected by the housing from entering the light receiving unit through the gap between the light shielding portion and the housing. Therefore, it is possible to suppress a decrease in the detection accuracy of the detection unit due to the light passing through the gap between the light shielding portion and the housing entering the light receiving unit.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

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Figure 11

Figure 12

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Figure 17

Figure 18

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the overall configuration of an image forming apparatus 1 in which the optical scanning device of the present invention is mounted. The image forming apparatus 1 is a tandem type color printer. The image forming apparatus 1 includes photosensitive drums 11a to 11d that are rotatable as image carriers. For the photosensitive drums 11a to 11d, an organic photoreceptor (OPC photoreceptor) having an organic photosensitive layer formed thereon, an amorphous silicon photoreceptor having an amorphous silicon photosensitive layer formed thereon, or the like is used. The photosensitive drums 11a to 11d are tandemly arranged corresponding to the colors yellow, magenta, cyan, and black.

[0014] Around the photosensitive drum 11a, a developing device 2a, a charger 13a, and a cleaning device 14a are disposed. Similarly, around each of the photosensitive drums 11b to 11d, developing devices 2b to 2d, chargers 13b to 13d, and cleaning devices 14b to 14d are respectively disposed. Further, an optical scanning device 12 is disposed below the developing devices 2a to 2d.

[0015] The developing devices 2a to 2d are respectively arranged to the right of the photosensitive drums 11a to 11d. The developing devices 2a to 2d face the photosensitive drums 11a to 11d respectively and supply toner to the photosensitive drums 11a to 11d. In this specification, right and left indicate right and left in the drawing.

[0016] The chargers 13a to 13d are arranged upstream of the developing devices 2a to 2d with respect to the rotation direction of the photosensitive drums 11a to 11d and face the surfaces of the photosensitive drums 11a to 11d respectively. The chargers 13a to 13d uniformly charge the surfaces of the photosensitive drums 11a to 11d respectively.

[0017] The optical scanning device 12 irradiates (optically scans) light onto the surfaces of the photosensitive drums 11a to 11d uniformly charged by the chargers 13b to 13d based on image data such as characters and patterns input from a personal computer or the like to an image input unit, and forms electrostatic latent images on the surfaces of the photosensitive drums 11a to 11d.

[0018] The housing 12a of the optical scanning device 12 includes a housing portion 12b with one surface open and a cover portion 12c covering the opening. The housing portion 12b incorporates a scanning optical system 120 inside. An emission port 12d (see FIG. 4) of light (laser light) emitted from the scanning optical system 120 is formed in the cover portion 12c corresponding to the photosensitive drums 11a to 11d. Further, as will be described later, the emission ports 12d are respectively covered with a transmissive member 52. The transmissive member 52 has transmissivity with respect to the light emitted from the scanning optical system 120.

[0019] The scanning optical system 120 includes a laser light source (not shown) and a polygon mirror. The scanning optical system 120 also includes at least one reflection mirror and a lens corresponding to the photoreceptor drums 11a to 11d. The laser light emitted from the laser light source is irradiated onto the surfaces of the photoreceptor drums 11a to 11d from the downstream side with respect to the rotation direction of the photoreceptor drums 11a to 11d via the polygon mirror, the reflection mirror group, and the lens group, downstream of the chargers 13a to 13d. Thereby, an electrostatic latent image is formed on the surfaces of the photoreceptor drums 11a to 11d. These electrostatic latent images are developed into toner images by the developing devices 2a to 2d.

[0020] The endless intermediate transfer belt 17 is stretched over the tension roller 6, the drive roller 25, and the driven roller 27. When the drive roller 25 is rotated by a motor (not shown), the intermediate transfer belt 17 is circulated and driven in the clockwise direction in FIG. 1.

[0021] The photoreceptor drums 11a to 11d are arranged adjacent to each other along the conveyance direction (the direction of the arrow in FIG. 1) below the intermediate transfer belt 17. The photoreceptor drums 11a to 11d are each in contact with the intermediate transfer belt 17. The primary transfer rollers 26a to 26d face the photoreceptor drums 11a to 11d with the intermediate transfer belt 17 interposed therebetween. The primary transfer rollers 26a to 26d are each pressed against the intermediate transfer belt 17 to form a primary transfer portion together with the photoreceptor drums 11a to 11d. In these primary transfer portions, the toner image is transferred to the intermediate transfer belt 17. Specifically, by applying a primary transfer voltage to the primary transfer rollers 26a to 26d, the toner images on the photoreceptor drums 11a to 11d are sequentially transferred to the intermediate transfer belt 17 at a predetermined timing. Thereby, a full-color toner image in which yellow, magenta, cyan, and black toner images are superimposed with a predetermined positional relationship is formed on the surface of the intermediate transfer belt 17.

[0022] The secondary transfer roller 34 faces the driving roller 25 with the intermediate transfer belt 17 interposed therebetween. The secondary transfer roller 34 is pressed against the intermediate transfer belt 17 and forms a secondary transfer portion together with the driving roller 25. In this secondary transfer portion, when a secondary transfer voltage is applied to the secondary transfer roller 34, the toner image on the surface of the intermediate transfer belt 17 is transferred onto the paper P. After the transfer of the toner image, the belt cleaning device 31 cleans the toner remaining on the intermediate transfer belt 17.

[0023] A paper feed cassette 32 is disposed below the image forming apparatus 1. The paper feed cassette 32 can store a plurality of sheets of paper P. To the right of the paper feed cassette 32, a stack tray 35 for manual paper feeding is disposed. To the left of the paper feed cassette 32, a first paper conveyance path 33 is disposed. The first paper conveyance path 33 conveys the paper P fed from the paper feed cassette 32 to the secondary transfer portion. Also, to the left of the stack tray 35, a second paper conveyance path 36 is disposed. The second paper conveyance path 36 conveys the paper fed from the stack tray 35 to the secondary transfer portion. Further, in the upper left of the image forming apparatus 1, a fixing unit 18 and a third paper conveyance path 39 are disposed. The fixing unit 18 performs a fixing process on the paper P on which an image has been formed. The third paper conveyance path 39 conveys the paper P on which the fixing process has been performed to the paper discharge portion 37.

[0024] The paper P stored in the paper feed cassette 32 is fed one by one to the first paper conveyance path 33 side by the pickup roller 33b and the deflector roller pair 33a.

[0025] The first paper conveyance path 33 and the second paper conveyance path 36 merge upstream (in front) of the registration roller pair 33c. The registration roller pair 33c conveys the paper P to the secondary transfer portion by timing the image forming operation on the intermediate transfer belt 17 and the paper feeding operation to the secondary transfer portion. With respect to the paper P conveyed to the secondary transfer portion, the full-color toner image on the intermediate transfer belt 17 is secondarily transferred by the secondary transfer roller 34 to which a secondary transfer voltage is applied. The paper P onto which the full-color toner image has been transferred is conveyed to the fixing unit 18.

[0026] The fixing unit 18 includes a fixing belt heated by a heater, a fixing roller inscribed in the fixing belt, a pressure roller pressed against the fixing roller with the fixing belt interposed therebetween, and the like. The fixing unit 18 heats and presses the sheet P onto which the toner image has been transferred. Thereby, the fixing process is performed. The sheet P on which the toner image has been fixed in the fixing unit 18 is reversed in front and back in the fourth sheet conveyance path 40 as necessary. Thereafter, the sheet P is conveyed to the secondary transfer portion again via the resist roller pair 33c, and then a new toner image is secondarily transferred onto the back surface of the sheet P by the secondary transfer roller 34 and fixed by the fixing unit 18. The sheet P on which the toner image has been fixed passes through the third sheet conveyance path 39 and is discharged to the sheet discharge portion 37 by the discharge roller pair 19.

[0027] Next, with reference to FIGS. 2 to 6, the optical scanning device 12 will be described. FIG. 2 is a perspective view of the optical scanning device 12 according to the first embodiment of the present invention. FIGS. 3 and 4 are enlarged perspective views around the cleaning holders 511 and 512 attached to the cover portion 12c of the optical scanning device 12. FIG. 5 is a cross-sectional view of the cleaning holder 511 attached to the cover portion 12c of the optical scanning device 12 as viewed from the moving direction. FIGS. 6 and 7 are plan views of the optical scanning device 12.

[0028] In the following drawings, the extending direction of the transmissive member 52 is defined as the X direction, X1 is one side of the extending direction of the transmissive member 52 approaching the detection unit 56, and X2 is the other side of the extending direction of the transmissive member 52 moving away from the detection unit 56. The parallel direction of the transmissive members 52 is defined as the Y direction, Y1 is one side of the parallel direction of the transmissive members 52, and Y2 is the other side of the extending direction of the transmissive member 52. Further, in FIG. 2, with the cleaning holders 511 and 512 on top with respect to the cover portion 12c, the shape and positional relationship of each part will be described. Note that the vertical direction is merely a name used for explanation and does not limit the direction when the optical scanning device 12 is incorporated into the image forming apparatus 1.

[0029] The optical scanning device 12 includes a housing 12a, a transmissive member 52, a linear member 54, a motor (drive unit) 55, a guide rail 61, a stopper 62, cleaning holders 511 and 512, a cleaning member 53, a detection unit 56, and a control unit 90 (see FIG. 10).

[0030] The housing 12a includes a housing portion 12b and a cover portion 12c attached to the housing portion 12b. Four laser light emission ports 12d (see FIG. 5) corresponding to the four photosensitive drums 11a to 11d are arranged in parallel on the cover portion 12c. The shape of each emission port 12d is a rectangular shape that is long in the main scanning direction (X direction) of the corresponding laser light, and the longitudinal directions (X direction) of the emission ports 12d are formed parallel to each other.

[0031] The transmissive member 52 is formed in a rectangular plate shape and seals each emission port 12d. This can prevent toner, dust, etc. from entering the inside of the optical scanning device 12 through each emission port 12d. The four transmissive members 52 are arranged in parallel such that their longitudinal directions (X direction) are parallel to each other. Each transmissive member 52 is, for example, a glass cover.

[0032] A pair of guide rails 61 are arranged on both sides sandwiching a pair of transmissive members 52. That is, four guide rails 61 are arranged in parallel. The guide rail 61 protrudes from the upper surface of the cover portion 12c and extends in the extending direction (X direction) of the transmissive member 52. The guide rail 61 has a guide rib 61a that protrudes outward from the tip and extends in the extending direction (X direction) of the transmissive member 52 (see FIG. 5).

[0033] The stopper 62 is arranged on one side (X1 side) in the extending direction of the guide rail 61 and restricts the movement of the cleaning holders 511 and 512 to one side (X1 side) in their extending directions, respectively. The stopper 62 is fixed to the upper surface of the cover portion 12c. In the present embodiment, the stopper 62 is provided on one side of the two guide rails 61 straddled by the cleaning holders 511 and 512, respectively, and extends in the parallel direction (Y direction) of the transmissive members 52.

[0034] The cleaning holders 511 and 512 are arranged on the upper surface of the cover portion 12c (the surface on the side of the photoreceptor drums 11a to 11d), and include a main body portion 51a, an engaging portion 51b, and first light-shielding portions 511a and 512a. The main body portion 51a is formed in a plate shape and extends in the parallel direction (Y direction) of the transmissive members 52 so as to straddle between two adjacent transmissive members 52.

[0035] The cleaning member 53 is fixed to the lower surface of the main body portion 51a (see FIG. 5). A pair of cleaning members 53 are arranged inside the engaging portion 51b in the parallel direction (Y direction). As the linear member 54 runs in a loop, each cleaning member 53 slides on the upper surface of each transmissive member 52 (the surface on the side of the photoreceptor drums 11a to 11d). Thereby, the upper surfaces of the respective transmissive members 52 are simultaneously cleaned by the corresponding cleaning members 53.

[0036] The cleaning member 53 is, for example, a rubber pad. For example, silicone rubber can be used as the material of the rubber pad. Each of the cleaning holders 511 and 512 is formed of, for example, resin. Note that each cleaning member 53 is not limited to a rubber pad and may be, for example, a non-woven fabric.

[0037] A pair of engaging portions 51b are arranged on both sides with a pair of guide rails 61 interposed therebetween. The engaging portion 51b protrudes downward from the bottom surface of the main body portion 51a and the tip portion bends toward the adjacent guide rail 61 side. The engaging portion 51b engages with the guide rib 61a. The cleaning holders 511 and 512 are guided along the corresponding pair of guide rails 61. Thereby, the cleaning holders 511 and 512 can stably move along the extending direction (X direction) on each transmissive member 52.

[0038] Further, the engaging portion 51b and the guide rib 61a are engaged with each other, and both end portions of the main body portion 51a are locked to the guide rails 61 in the direction away from the housing 12a of the optical scanning device 12 (the upward direction in FIG. 5). Thereby, the upward movement (displacement) of the cleaning holders 511 and 512 is restricted, and detachment from the cover portion 12c can be prevented. Therefore, the cleaning members 53 can be stably brought into close contact with the respective transmissive members 52.

[0039] On the other side (X2 side) in the extending direction of the guide rail 61, it is open in the extending direction (X direction) of the guide rail 61 (see FIGS. 6 and 7). Thereby, the cleaning holders 511 and 512 can be easily incorporated into the guide rail 61 by sliding the cleaning holders 511 and 512 to the one side (X1 side) in the extending direction of the guide rail 61 while engaging the engaging portion 51b with the guide rib 61a from the other end in the extending direction of the guide rail 61. Therefore, the assembling workability of the optical scanning device 12 can be improved.

[0040] Note that the engaging portion 51b and the guide rib 61a are an example of the engagement between the cleaning holders 511 and 512 and the cover portion 12c, and the present invention is not limited to this structure.

[0041] The first light-shielding portion 511a is disposed at the side end portion on one side (Y1 side) in the parallel direction of the main body portion 51a in the cleaning holder 511 and protrudes in one direction (X1 direction) in the extending direction (see FIGS. 6 and 7). The second light-shielding portion 512a is disposed at the side end portion on the other side (Y2 side) in the parallel direction of the main body portion 51a in the cleaning holder 512 and protrudes in one direction (X1 direction) in the extending direction (see FIGS. 6 and 7). The shapes of the first light-shielding portion 511a and the second light-shielding portion 512a will be described in detail later.

[0042] The main body portion 51a has a recess 51c that is recessed downward from the upper surface, and a linear member 54 is fitted in the recess 51c. Further, the recess 51c has a protrusion 51d that protrudes inward from the inner surface. By providing the protrusion 51d, the linear member 54 is bent within the recess 51c. Thereby, the cleaning holders 511 and 512 and the linear member 54 are firmly fixed. Note that the recess 51c may be formed to be recessed upward from the lower surface of the main body portion 51a.

[0043] The linear member 54 includes, for example, a timing belt or a wire. The linear member 54 passes between two transmissive members 52 in the housing 12a and is annularly stretched between four stretching pulleys 57. The linear member 54 extends parallel to the extending direction (X direction) of each transmissive member 52 between two adjacent transmissive members 52. The four stretching pulleys 57 are rotatably held on the upper surface of the cover portion 12c.

[0044] Also, one of the stretching pulleys 57 is connected to a gear 57a disposed on the lower surface of the cover portion 12c (see FIGS. 6 and 7). The gear 57a is connected to a motor 55. When the motor 55 rotates the gear 57a, the linear member 54 runs annularly.

[0045] The motor (drive unit) 55 is disposed outside the linear member 54 and fixed to the lower surface of the cover portion 12c. That is, the upper end of the motor 55 is disposed below the upper end of the linear member 54. Thereby, space can be saved on the upper surface of the cover portion 12c. Further, by disposing the motor 55 outside the linear member 54, the maintainability of the motor 55 and the gear 57a is improved. The motor 55 can rotate forward and backward. By driving the motor 55, the linear member 54 runs annularly in the clockwise direction (D2 direction) or counterclockwise direction (D1 direction) in a top view (see FIGS. 6 and 7). Thereby, the cleaning holders 511 and 512 reciprocate along the longitudinal direction of the transmissive member 52 (the main scanning direction of the laser beam). Further, in the reciprocating movement, the cleaning holder 511 and the cleaning holder 512 linearly move in opposite directions to each other.

[0046] Note that the cleaning process is executed when the state of the image forming apparatus 1 is in the maintenance mode and the user inputs a process start command from the operation unit 80 (see FIG. 10) or a host device such as a personal computer. Further, for example, the cleaning process may be periodically executed each time printing (image formation) of about 10,000 sheets is performed.

[0047] The detection unit 56 is disposed on one side (X1 side) in the extending direction of the transmissive member 52, and is disposed between the movement path of the cleaning holder 511 and the movement path of the cleaning holder 512 in the parallel direction (Y direction) of the transmissive member 52 (see FIGS. 6 and 7). The detection unit 56 detects that one of the cleaning holders 511 and 512 has reached one end of the movement paths of the cleaning holders 511 and 512. Note that the cleaning holders 511 and 512 that have reached one end of the movement path come into contact with the stopper 62, and the movement to one side (X1 side) in the extending direction is restricted.

[0048] The detection unit 56 is a transmissive optical sensor (photointerrupter) having a light emitting unit 56a and a light receiving unit 56b, and one sensor can detect that either the cleaning holder 511 or the cleaning holder 512 has reached one end of the movement path. The light emitting unit 56a emits light in the parallel direction (Y direction) of the transmissive member 52. The light receiving unit 56b receives the light emitted from the light emitting unit 56a. In the present embodiment, the light emitting unit 56a is disposed on one side (Y1 side) in the parallel direction with respect to the light receiving unit 56b, but the light emitting unit 56a may be disposed on the other side (Y2 side) in the parallel direction with respect to the light receiving unit 56b.

[0049] Next, with reference to FIGS. 8 and 9, the detection unit 56 and the first light shielding portions 511a and 512a will be described. FIGS. 8 and 9 are perspective views schematically showing the detection unit 56 and the first light shielding portions 511a and 512a. FIG. 8 shows the positional relationship between the detection unit 56 and the first light shielding portion 511a, and FIG. 9 shows the positional relationship between the detection unit 56 and the second light shielding portion 512a.

[0050] The first light shielding portion 511a and the second light shielding portion 512a have different shapes. In the present embodiment, the second light shielding portion 512a is formed with a through hole 512b penetrating in the parallel direction (Y direction) (see FIG. 9), but the first light shielding portion 511a is not formed with the through hole 512b (see FIG. 8).

[0051] As a result, when the cleaning holder 511 or the cleaning holder 512 reaches one end of the moving path, the light receiving patterns received by the light receiving portion 56b are different between the first light shielding portion 511a and the second light shielding portion 512a.

[0052] Specifically, when the tip of the first light shielding portion 511a moving in one side (X1 side) of the extending direction is inserted between the light emitting portion 56a and the light receiving portion 56b, the light emitted from the light emitting portion 56a is blocked by the tip of the first light shielding portion 511a. As a result, the light receiving portion 56b cannot receive the light emitted from the light emitting portion 56a. At this time, the detection portion 56 is turned on. Further, by moving the first light shielding portion 511a in one side (X1 side) of the extending direction, the cleaning holder 511 reaches one end of the moving path and contacts the stopper 62. As a result, the movement of the cleaning holder 511 in one side (X1 side) of the extending direction is restricted. At this time, the light emitted from the light emitting portion 56a is blocked by the first light shielding portion 511a, and the detection portion 56 is maintained in the on state (see FIG. 8).

[0053] On the other hand, when the tip of the second light shielding portion 512a moving in one side (X1 side) of the extending direction is inserted between the light emitting portion 56a and the light receiving portion 56b, the light emitted from the light emitting portion 56a is blocked by the tip of the second light shielding portion 512a. As a result, the light receiving portion 56b cannot receive the light emitted from the light emitting portion 56a. At this time, the detection portion 56 is turned on. Further, by moving the second light shielding portion 512a in one side (X1 side) of the extending direction, the cleaning holder 512 reaches one end of the moving path and contacts the stopper 62. As a result, the movement of the cleaning holder 512 in one side (X1 side) of the extending direction is restricted. At this time, the light emitted from the light emitting portion 56a passes through the through hole 512b and is received by the light receiving portion 56b, and the detection portion 56 is switched to the off state (see FIG. 9).

[0054] As a result, during the execution of the cleaning mode, when the on state continues for a predetermined time, the detection unit 56 can detect that the cleaning holder 511 has reached one end of the movement path of the cleaning holder 511. Further, during the execution of the cleaning mode, when the on state switches to the off state after continuing for a predetermined time, the detection unit 56 can detect that the cleaning holder 512 has reached one end of the movement path of the cleaning holder 512. At this time, the running of the linear member 54 stops. That is, when one of the cleaning holders 511 and 512 reaches one end of the movement path and its movement is restricted by the stopper 62, the other of the cleaning holders 511 and 512 stops moving. Thereby, on the other side (X2 side) in the extending direction of the opened guide rail 61, it is possible to prevent the other of the cleaning holders 511 and 512 from coming off the guide rail 61.

[0055] Next, returning to FIGS. 6 and 7, the operation of the cleaning holder 51 will be described. In the present embodiment, as described above, in one cleaning process, the corresponding cleaning member 53 reciprocates once along the extending direction (X direction) of each permeable member 52. Here, a case will be described in which, during the cleaning process, the running direction of the linear member 54 changes from the direction indicated by the arrow D1 (first direction) to the direction indicated by the arrow D2 (second direction).

[0056] At the start of the cleaning process, the cleaning holder 511 turns on the detection unit 56 at one end of its movement path (see FIG. 6). By setting the state in which the cleaning holder 511 is disposed at one end of the movement path as the initial position at the start of the execution of the cleaning mode, the detection unit 56 can detect the cleaning holder 511 in the on state. Thereby, it is possible to prevent the occurrence of an initial error in the cleaning process.

[0057] When the cleaning process starts, the linear member 54 travels in the first direction indicated by the arrow D1 (see FIG. 6). As a result, the cleaning holders 511 and 512 move from the position shown in FIG. 6 to the position shown in FIG. 7, and the detection unit 56 detects that the cleaning holder 512 has reached one end of the movement path, and stops the travel of the linear member 54. Thereby, the cleaning holders 511 and 512 stop.

[0058] Next, the rotation direction of the motor 55 is reversed, and the linear member 54 travels in the second direction (opposite to the first direction) indicated by the arrow D2 (see FIG. 7). As a result, the cleaning holders 511 and 512 move from the position shown in FIG. 7 to the position shown in FIG. 6, and the detection unit 56 detects that the cleaning holder 511 has reached one end of the movement path, and stops the travel of the linear member 54. Thereby, the operations of the cleaning holders 511 and 512 stop.

[0059] FIG. 10 is a block diagram showing an example of a control path used in the image forming apparatus 1. Since various controls of each part of the apparatus are performed when using the image forming apparatus 1, the control path of the entire image forming apparatus 1 becomes complicated. Therefore, here, the parts necessary for the implementation of the present invention in the control path will be mainly described.

[0060] The voltage control circuit 71 is connected to the motor drive power supply 73 and operates the motor drive power supply 73 by an output signal from the control unit 90. The motor drive power supply 73 applies a predetermined drive voltage to the motor 55 in the optical scanning device 12 according to a control signal from the voltage control circuit 71.

[0061] The operation unit 80 is provided with a liquid crystal display unit 81 and LEDs 82 indicating various states, and is configured to indicate the state of the image forming apparatus 1, display the image forming status, the number of printed sheets, and the like. Various settings of the image forming apparatus 1 are made from the printer driver of the personal computer.

[0062] The control unit 90 includes at least a CPU (Central Processing Unit) 91 as a central processing unit, a ROM (Read Only Memory) 92 which is a read-only storage unit, a RAM (Random Access Memory) 93 which is a rewritable storage unit, a timer 95, and an I / F (interface) 96 that transmits control signals to each device in the image forming apparatus 1 and receives input signals from the operation unit 70.

[0063] The ROM 92 stores data such as a control program for the image forming apparatus 1 and numerical values necessary for control that should not be changed during the use of the image forming apparatus 1. The RAM 93 stores necessary data generated during the control of the image forming apparatus 1 and data temporarily required for the control of the image forming apparatus 1. Further, in the RAM 93 (or ROM 92), voltage values (DUTY) applied to the motor 55 and the driving time of the motor 55 in each operation mode of the cleaning holder 51 described later are also stored during the cleaning of the transmissive member 52 of the optical scanning device 12. The timer 95 measures the driving time of the motor 55.

[0064] According to the present embodiment, during the execution of the cleaning mode, when the detection unit 56 detects that one of the cleaning holders 512 has reached one end of the movement path, the forward movement operation is started, and when the detection unit 56 detects that the other of the cleaning holders 511 has reached one end of the movement path, the return movement operation is started. That is, the control unit 90 can determine the switching between the return movement operation and the forward movement operation based on the detection result of the detection unit 56, thereby reducing the load applied to the linear member 54 and preventing the stretching pulley 57 from being damaged.

[0065] Further, the shapes of the first light-shielding portion 511a and the second light-shielding portion 512a are different, and the second light-shielding portion 512a has a through hole 512b. Thereby, the detection unit 56 can detect which of the cleaning holder 511 or the cleaning holder 512 has reached one end of the movement path based on the light reception pattern received by the light receiving unit 56b. Therefore, the detection unit 56 can be simplified and the manufacturing cost of the optical scanning device 12 can be reduced.

[0066] Further, by forming the through hole 512b in the second light-shielding portion 512a, it is possible to easily detect which of the cleaning holder 511 or the cleaning holder 512 has reached one end of the movement path by the light-receiving pattern received by the light-receiving portion 56b.

[0067] Also, at the start of execution of the cleaning mode, by setting the state in which the cleaning holder 511 is disposed at one end of the movement path as the initial position, the detection unit 56 can detect the cleaning holder 511 while being in the on state. Thereby, it is possible to prevent the occurrence of an initial error in the cleaning process.

[0068] Further, at the start of execution of the cleaning mode, the control unit 90 determines with the detection unit 56 which of the cleaning holder 511 or the cleaning holder 512 is disposed at one end of the movement path, and determines which of the forward movement operation or the return movement operation to start. Thereby, even when either the cleaning holder 511 or the cleaning holder 512 was disposed at one end of the movement path when the execution of the previous cleaning mode ended, the start of the cleaning operation can be quickly performed.

[0069] FIG. 11 and FIG. 12 are a perspective view and a plan view respectively showing a state in which the detection unit 56 of the optical scanning device 12 of the first embodiment is shielded by the first light-shielding portion 511a. FIG. 13 is a cross-sectional view (a cross-sectional view taken along the arrow AA in FIG. 12) of the state in which the detection unit 56 of the optical scanning device 12 of the first embodiment is shielded by the first light-shielding portion 511a as viewed from the movement direction of the cleaning holder 511.

[0070] As shown in FIG. 11, the detection unit 56 is horizontally disposed along the upper surface of the cover portion 12c such that the longitudinal directions of the light-emitting unit 56a and the light-receiving unit 56b are parallel to the movement direction (X1, X2 directions) of the cleaning holder 511. Thereby, the protruding amount of the detection unit 56 in the height direction can be made smaller compared to the case where the light-emitting unit 56a and the light-receiving unit 56b are disposed vertically, and the height of the optical scanning device 12 can be made smaller (lower profile). On the other hand, in the above configuration, the distances between the light-emitting unit 56a and the light-receiving unit 56b and the upper surface of the cover portion 12c become smaller.

[0071] Also, as shown in FIG. 13, a gap is formed between the first light-shielding portion 511a provided on the cleaning holder 511 and the upper surface of the cover portion 12c. Thereby, the frictional resistance between the upper surface of the cover portion 12c when the cleaning holder 511 moves can be eliminated, and the cleaning holder 511 can be smoothly moved.

[0072] As shown in FIGS. 12 and 13, the first light-shielding portion 511a of the cleaning holder 511 is disposed on the light-emitting portion 56a side rather than at the center portion in the facing direction of the light-emitting portion 56a and the light-receiving portion 56b. Therefore, with the first light-shielding portion 511a of the cleaning holder 511 shielding the optical path between the light-emitting portion 56a and the light-receiving portion 56b, the light emitted from the light-emitting portion 56a passes through the gap between the first light-shielding portion 511a and the cover portion 12c.

[0073] As a result, there is a possibility that the light passing through the gap between the first light-shielding portion 511a and the cover portion 12c is reflected by the upper surface of the cover portion 12c and enters the light-receiving portion 56b, and there is a possibility that the detection accuracy of the detection unit 56 may decrease.

[0074] In the present embodiment, on the upper surface of the cover portion 12c extending along the facing direction (Y1, Y2 directions) of the light-emitting portion 56a and the light-receiving portion 56b of the detection unit 56, in a region facing the space between the light-emitting portion 56a and the light-receiving portion 56b, a light-shielding rib 63 (light leakage prevention portion) is formed. The light-shielding rib 63 protrudes upward from the cover portion 12c at a substantially central portion in the facing direction of the light-emitting portion 56a and the light-receiving portion 56b. In other words, the light-shielding rib 63 protrudes to the side opposite to the light-emitting portion 56a (light-receiving portion 56b side) with the first light-shielding portion 511a interposed therebetween.

[0075] FIG. 14 is an enlarged view showing the positional relationship in the height direction of the light-emitting portion 56a, the first light-shielding portion 511a, and the light-shielding rib 63 in FIG. 13. As shown in FIG. 14, the height h1 of the light-shielding rib 63 from the upper surface of the cover portion 12c is made smaller than the height h2 to the lower end portion of the light emission region 56a1 of the light-emitting portion 56a, and is made equal to or greater than the gap h3 between the cover portion 12c and the first light-shielding portion 511a. That is, the height h1 of the light-shielding rib 63 is determined so as to satisfy the following inequality (1). h3 ≤ h1 < h2 ···(1)

[0076] By satisfying h3 ≤ h1, the light that passes through the gap between the first light-shielding portion 511a and the cover portion 12c and is reflected by the upper surface of the cover portion 12c (the dashed arrow in FIG. 13) can be surely shielded by the light-shielding rib 63. Also, by satisfying h1 < h2, there is no longer a risk that the light-shielding rib 63 will block the optical path from the light-emitting portion 56a to the light-receiving portion 56b.

[0077] When the cleaning holder 512 reaches one end of the movement path, the second light-shielding portion 512a of the cleaning holder 512 is inserted on the light-receiving portion 56b side rather than at the center in the facing direction between the light-emitting portion 56a and the light-receiving portion 56b. Also in this case, since the light reflected by the upper surface of the cover portion 12c is shielded by the light-shielding rib 63, there is no risk that the light reflected by the upper surface of the cover portion 12c will pass through the gap between the second light-shielding portion 512a and the cover portion 12c and enter the light-receiving portion 56b.

[0078] FIG. 15 is a plan view showing the configuration around the detection portion 56 of the optical scanning device 12 according to the second embodiment of the present invention. FIG. 16 is a cross-sectional view of the detection portion 56 of the optical scanning device 12 of the second embodiment as viewed from the moving direction of the cleaning holder 511 with the detection portion 56 shielded by the first light-shielding portion 511a. In the present embodiment, instead of the light-shielding rib 63 of the first embodiment, a rough surface portion 65 (reflection suppression portion) is formed on the upper surface of the cover portion 12c that faces between the light-emitting portion 56a and the light-receiving portion 56b.

[0079] The rough surface portion 65 has fine irregularities formed over the entire area of the cover portion 12c that faces the space between the light-emitting portion 56a and the light-receiving portion 56b, and has a lower reflectance than other portions of the cover portion 12c. The rough surface portion 65 is formed by roughening the upper surface of the cover portion 12c by means of dimpling (pear surface) processing. The light that has passed through the gap between the first light-shielding portion 511a and the cover portion 12c (the dashed arrow in FIG. 16) becomes scattered light that is scattered in irregular directions after being reflected by the rough surface portion 65. Therefore, it is possible to suppress a decrease in the detection accuracy of the detection portion 56 due to the light that has passed through the gap between the first light-shielding portion 511a and the cover portion 12c entering the light-receiving portion 56b.

[0080] FIG. 17 is a plan view showing the configuration around the detection unit 56 of the optical scanning device 12 according to the third embodiment of the present invention. FIG. 18 is a cross-sectional view of the detection unit 56 of the optical scanning device 12 according to the third embodiment as viewed from the moving direction of the cleaning holder 511 in a state where the detection unit 56 is shielded by the first light shielding portion 511a. In the present embodiment, instead of the rough surface portion 65 of the second embodiment, a reflection suppression sheet 67 (reflection suppression portion) is attached to the upper surface of the cover portion 12c facing each other between the light emitting portion 56a and the light receiving portion 56b.

[0081] The reflection suppression sheet 67 is formed of a material having a lower reflectance than the cover portion 12c, and is fixedly attached to the entire area of the cover portion 12c facing the space between the light emitting portion 56a and the light receiving portion 56b. The light (dashed arrow in FIG. 18) that has passed through the gap between the first light shielding portion 511a and the cover portion 12c becomes scattered light that scatters in irregular directions after entering the reflection suppression sheet 67. Therefore, similarly to the second embodiment, it is possible to suppress a decrease in the detection accuracy of the detection unit 56 due to the light that has passed through the gap between the first light shielding portion 511a and the cover portion 12c entering the light receiving portion 56b. As the reflection suppression sheet 67, for example, a sheet (embossed sheet) in which the surface of a resin film such as polycarbonate is roughened, an ND filter (attenuating filter), or the like can be used.

[0082] In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiments, the optical scanning device 12 including the pair of cleaning holders 511 and 512 that reciprocate in opposite directions by the travel of the linear member 54 has been described. However, the present invention can be similarly applied to an optical scanning device 12 including only one cleaning holder.

[0083] In addition, in each of the above embodiments, the image forming apparatus 1 on which the optical scanning device 12 is mounted has been described by taking a tandem type color printer as an example. However, the present invention is not limited to a color printer, and is applicable to electrophotographic image forming apparatuses including a color copying machine, a monochrome printer, a monochrome copying machine, a digital multifunction peripheral, a facsimile machine, etc., which are equipped with the optical scanning device 12.

Industrial Applicability

[0084] The present invention is applicable to an optical scanning device that irradiates an image carrier with light to form an electrostatic latent image. By using the present invention, it is possible to provide an optical scanning device that does not reduce the detection accuracy when using a transmissive detection unit and can maintain smooth movement of the cleaning holder, and an image forming apparatus equipped with the same.

Explanation of Signs

[0085] 1 Image forming apparatus 12 Optical scanning device 12a Housing 12b Accommodating part 12c Cover part 12d Exit port 511, 512 Cleaning holder 51a Main body part 51b Engaging part 51c Recess 51d Protrusion 511a First light shielding part 512b Second light shielding part 52 Transparent member 53 Cleaning member 54 Linear member 55 Motor 56 Detection unit 56a Light emitting part 56b Light receiving part 61 Guide rail 61a Guide rib 63 Light shielding rib (light leakage prevention part) 65 Rough surface part (light leakage prevention part, reflection suppression part) 67 Reflection suppression sheet (light leakage prevention part, reflection suppression part) 90 Control unit 120 Scanning optical system Pa~Pd Image forming unit

Claims

1. An optical scanning device that irradiates a laser beam onto an image carrier to form an electrostatic latent image, comprising: a housing corresponding to the image carrier, the housing having an emission port of the laser beam extending in the main scanning direction of the laser beam; a transmissive member having transmissivity with respect to the laser beam, extending in the main scanning direction of the laser beam, and sealing the emission port of the laser beam; a linear member annularly stretched on the housing; a driving unit that runs the linear member in a predetermined direction; a guide rail arranged in parallel with the emission port and extending in the extending direction of the transmissive member; a cleaning holder fixed to the linear member and moving on the transmissive member along the guide rail when the linear member is run by the driving unit; a cleaning member fixed to the cleaning holder and cleaning the transmissive member by sliding with respect to the transmissive member as the cleaning holder moves; a detection unit arranged on one side in the extending direction of the transmissive member and detecting that the cleaning holder has reached one end of the moving path of the cleaning holder; a control unit that controls the driving of the driving unit; The optical scanning device further comprises: The detection unit includes: a light emitting unit that emits light in the parallel direction of the transmissive member; a light receiving unit that receives the light emitted from the light emitting unit; The light emitting unit and the light receiving unit are arranged along the housing such that the longitudinal directions of the light emitting unit and the light receiving unit are parallel to the moving direction of the cleaning holder. The cleaning holder has a light shielding portion that is arranged between the light emitting unit and the light receiving unit and shields the light emitted from the light emitting unit when reaching one end of the moving path. A gap is formed between the light shielding portion and the housing. The housing is characterized in that a light leakage prevention portion is formed between the light emitting unit and the light receiving unit.

2. The optical scanning device according to claim 1, wherein the light leakage prevention portion is a light shielding rib protruding from the housing into the space between the light emitting unit and the light receiving unit.

3. When the protruding height of the light shielding rib from the housing is h1, the height from the housing to the light emission region of the light emitting unit is h2, and the gap between the housing and the light shielding portion is h3, the optical scanning device according to claim 2 is characterized in that the following formula (1) is satisfied. h3 ≦ h1 < h2... (1)

4. The optical scanning device further comprises a pair of cleaning holders that move in opposite directions on adjacent transmissive members along the guide rail when the linear member is run by the driving unit. One of the pair of the cleaning holders has a first light-shielding portion as the light-shielding portion, and the other of the pair of the cleaning holders has a second light-shielding portion having a shape different from that of the first light-shielding portion. When one of the cleaning holders reaches one end of the movement path, the first light-shielding portion is disposed between the light-emitting portion and the light-shielding rib. The optical scanning device according to claim 2, wherein when the other cleaning holder reaches one end of the movement path, the second light-shielding portion is disposed between the light-shielding rib and the light-receiving portion.

5. The light leakage prevention portion is a reflection suppression portion formed over the entire portion facing the space between the light-emitting portion and the light-receiving portion of the housing and having a lower reflectance than other portions of the housing, according to claim 1. The optical scanning device described.

6. The optical scanning device according to claim 5, wherein the reflection suppression portion is a rough surface portion having fine irregularities formed on the surface of the housing.

7. The optical scanning device according to claim 5, wherein the reflection suppression portion is a reflection suppression sheet that is affixed and fixed to the surface of the housing and has a lower reflectance than the housing.

8. An image forming unit including one or more of the image carriers; The optical scanning device according to any one of claims 1 to 7, which irradiates the image carrier with laser light to form an electrostatic latent image; An image forming apparatus comprising:

Images