JP4871577B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning device for performing optical writing in an electrophotographic printer or the like and an image forming apparatus equipped with the optical scanning device.

JP 2000-263839 A

  Image forming apparatuses such as laser beam printers, digital copying machines, and laser facsimiles include an optical scanning device for writing a latent image on a photosensitive member. In recent years, there has been a demand for higher image quality in image forming apparatuses, and in optical scanning devices, dirt such as dust and toner adheres to the laser beam emitting part, and the problem that the image quality deteriorates by blocking the laser beam is also serious. It has become. On the other hand, with the demand for downsizing of the image forming apparatus, the arrangement of the optical writing unit (optical scanning apparatus) in the image forming apparatus has been diversified, and it is horizontal with respect to the image carrier or below it. May be placed. With such a configuration, there is a problem that dirt in the image forming apparatus is likely to adhere to a transparent member such as dust-proof glass provided at the laser emission port. Furthermore, recently, there is a tendency to use a toner having a shape close to a sphere compared to conventional toner. The toner having a shape close to a sphere has a difficulty in cleaning performance, and cleaning by the conventional technique may be insufficient. Therefore, for example, Patent Document 1 proposes to provide a shutter mechanism between the image carrier and the optical scanning device.

  However, if the shutter mechanism is arranged between the image carrier and the body light scanning device, a space required in the vertical direction in the image forming apparatus becomes large, which is in conflict with the demand for downsizing the apparatus.

  In addition, since the gap between the shutter mechanism and the optical scanning device is large in the one described in Patent Document 1, there is a problem that toner, dust, or the like enters from the lateral direction, and deterioration in image quality cannot be sufficiently prevented. is there.

  An object of the present invention is to solve the above-described problems in a conventional optical scanning device, and to provide an optical scanning device and an image forming apparatus that save space and do not deteriorate image quality.

According to the present invention, there is provided an optical scanning device that scans a surface to be scanned by emitting a light beam from a light source from an exit window of an optical housing, and includes a shutter member that shields and opens the exit window. The member is urged by the urging means in the direction of shielding the exit window, and the shutter member is moved through one link mechanism comprising a pair of lever members, and the link mechanism is driven means. The one lever member operated by the actuator is configured to operate the other lever member, and an end portion of the one lever member is bent to form a flat portion, and the flat portion is brought into contact with the driving means. And the other lever member end is driven through the flat portion of the one lever member .

Further, the link mechanism has both end portions in a direction in which a force point by the driving means is at a central portion in the longitudinal direction of the exit window and an action point at which each lever member acts on the shutter member is perpendicular to the moving direction of the shutter member. It is preferable to be provided in the vicinity .

Moreover, it is preferable that the length from the pivot point of the lever member to the action point is set larger than the length from the force point to the pivot point .

Further, it is preferable that the urging means urges the lever member.
The biasing means is preferably a torsion coil spring mounted on the rotation shaft of the lever member.

Further, it is preferable that the optical housing is provided with a plurality of shutter guide portions extending in the moving direction of the shutter member and supporting the shutter member.
The shutter guide portion is preferably formed in a thin rib shape.

Further, a plurality of the exit window, the shutter member is not preferred if there a member that shields and opening together said plurality of exit window.

According to the present invention, the above problem is solved by an image forming apparatus comprising the optical scanning device according to any one of claims 1 to 8 .

  According to the optical scanning device and the image forming apparatus of the present invention, since the shutter member that shields and opens the light emission window from the housing of the optical scanning device is provided, the vertical space is not increased. This can contribute to downsizing of the image forming apparatus. In addition, it is possible to prevent intrusion of toner and dust from the lateral direction, and to effectively prevent deterioration of image quality due to the adhesion of the toner and dust to the dust-proof glass.

  Further, since the shutter member is urged by the urging means in the direction of shielding the exit window, it is possible to minimize the contamination caused by the adhesion of toner or dust to the dust-proof glass provided in the exit window of the light beam. It becomes. Therefore, a good image can be continuously maintained.

  The biasing means biases the shutter member in the closing direction, so that it is necessary to replace the optical scanning device for assembly in the factory, repair, etc., or for the optical scanning device. It prevents dust from adhering to the dust-proof glass during transportation, etc., and also prevents the dust-proof glass from being damaged or damaged due to work mistakes, etc., thus protecting an expensive optical scanning device. It becomes.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram illustrating an outline of an image forming apparatus including an example of an optical scanning device according to the present invention. The full-color printer 50 shown in this figure is a so-called quadruple tandem image forming apparatus. Four image forming units (for four colors) are arranged facing the transfer belt 51, and toner images on the respective photoreceptors 9 are arranged. Are transferred onto the transfer belt 51 and transferred onto a recording material fed from the paper supply unit 52, and a full-color image can be obtained in a short time.

  The transfer belt 51 is rotated counterclockwise in the drawing. Four image forming units (for four colors) centering on the photosensitive drum 9 are arranged in parallel below the transfer belt 51. The configuration of each color image forming unit is the same, and only the color of the toner used is different. In this example, each color image forming unit forms an image using cyan, magenta, yellow, and black (symbols indicating the colors of C, M, Y, and K are written in the photosensitive drum 9). . An optical scanning device 15 is disposed below the image forming unit. The recording material fed from the paper feeding unit 52 is sent out in timing with the toner image on the transfer belt 51 by the registration roller 53, and the toner on the transfer belt 51 is operated by the transfer roller 54 as a transfer unit. The image is transferred to the recording material. The toner image on the recording material is fixed by the fixing device 55, and the recording material is discharged to the discharge tray 57 by the discharge roller 56 and stacked.

FIG. 2 is an enlarged view showing the vicinity of the optical scanning device 15 in detail.
As shown in this figure, the optical scanning device 15 includes two-stage polygon mirrors 1a and 1b, soundproof glasses 2a and 2b, fθ lenses 3a and 3b, and first to third mirror groups 4a, 4b, 4c, 4d, and 6a. , 6b, 6c, 6d, 7a, 7b, 7c, 7d, long lenses 5a, 5b, 5c, 5d, dust-proof glass 8a, 8b, 8c, 8d, etc., which are arranged in the optical housing 13. Has been.

  The polygon mirror 1 has a reflection mirror on the side of a regular polygon, is rotated at a high speed by a polygon motor (not shown), and deflects and scans laser light from a light source (not shown). The soundproof glass 2 is for soundproofing the sound generated by the polygon motor. The fθ lens 3 is an optical element that changes the equiangular motion of the beam scanning by the polygon mirror 1 into a uniform linear motion. The first to third mirror groups 4, 6, and 7 are optical elements that guide laser beams to the respective photosensitive members 9 disposed above the optical scanning device 15. The long lens 5 corrects the tilting of the polygon mirror and has a function of correcting the position of the scanning line in the sub-scanning direction. The dust-proof glass 8 prevents dust and the like from falling into the optical housing 13.

  The optical housing 13 includes a side wall 13a, an optical element arrangement surface 13b, an upper cover 11 and a lower cover 12 for sealing the housing, and a lid 10 for a polygon mirror portion. A shutter member 14 is slidably and integrally mounted on the upper cover 11. In FIGS. 1 and 2, the optical path to each photoconductor is indicated by reference numerals L1, L2, L3, and L4.

  FIG. 3 is a perspective view showing the optical scanning device 15 and its shutter driving mechanism. In this figure, reference numeral 58 denotes a face plate provided on the main body side of the image forming apparatus, and the optical scanning device 15 causes the right side wall 13a of the housing 13 in FIG. Positioned and fixed to the body.

  As shown in FIG. 3, the shutter member 14 mounted on the upper surface of the optical housing 13 has three guide grooves 16 extending in a direction perpendicular to the main scanning direction (longitudinal direction of the optical scanning device 15). A stepped screw 17 is screwed into the upper cover 11 so as to hold the shutter member 14 in each guide groove 16. The stepped screw 17 restricts the shutter member 14 from being lifted from the upper cover 11, and ensures an appropriate interval necessary for sliding the shutter member 14. As indicated by a double arrow A, the shutter member 14 is It is supported so that it can reciprocate.

  The shutter member 14 has three openings 18 provided in parallel with the main scanning direction in order to allow scanning light to pass through. FIG. 3 shows a state in which the shutter is closed. The shutter member 14 is moved in the A1 direction from the shutter closed position, and the shutter is opened by taking the position shown in FIG. In the shutter open position, the three openings 18 are positioned above the dust-proof glasses 8b, 8c, and 8d on the upper surface of the housing. Note that the opening corresponding to the dustproof glass 8a at the left end in FIG. 2 is not provided in the shutter member 14, and the dustproof glass 8a is moved by moving the left end of the shutter member 14 to the right position of the dustproof glass 8a in FIG. Is opened above. In this way, the shutter is opened, and the scanning lights L1 to L4 can be exposed through the dust-proof glasses 8a, 8b, 8c, and 8d.

  Then, when the shutter member 14 is moved in the A2 direction from the shutter open position of FIG. 2 and the shutter is closed as shown in FIG. 3, the openings 18 of the shutter member 14 are moved from the positions of the dustproof glasses 8b, 8c, and 8d. As a result of the displacement and the end of the shutter member 14 moving above the dust-proof glass 8a, all the dust-proof glass 8a, 8b, 8c, and 8d are covered by the shutter member 14.

  In the optical scanning device 15 of this example, since the shutter member 14 is provided integrally with the optical housing 13, it is possible to contribute to downsizing of the image forming apparatus without increasing the vertical space. . Further, since the shutter member 14 is provided integrally with the optical housing 13, there is no gap between the conventional shutter member and the optical scanning device, preventing intrusion of toner or dust from the lateral direction, It is possible to effectively prevent the image quality from being deteriorated due to the adhesion to the dust-proof glass.

Next, the shutter drive mechanism will be described with reference to FIGS.
A pair of levers 20, 20 that are link members are rotatably attached to shafts 19, 19 at one end in the longitudinal direction of the upper surface of the upper cover 11 of the optical housing. The shafts 19 and 19 are fitted with torsion coil springs 21 and 21, respectively. The coil springs 21 and 21 have one end engaged with the levers 20 and 20 and the other end engaged with locking portions 23 and 23 provided on the upper cover 11, and the left lever 20 in FIG. The right lever 20 is urged counterclockwise in the figure in the clockwise direction. That is, the torsion coil spring 21 biases the shutter member 14 in the closing direction.

  A pin receiving hole 20a is formed at the outer end of each lever 20, and pins 22 and 22 projecting downward (planted) to the end of the shutter member 14 are loosely fitted into the pin receiving hole 20a. Is done. Therefore, when the pair of levers 20 and 20 rotate about the shafts 19 and 19, the shutter member 14 is moved in the vertical direction in FIG. 4 (longitudinal direction of the optical scanning device 15: arrow A direction in FIG. 1). . In this example, the length of the portion (outer portion) from the shaft 19 to the pin receiving hole 20a in the lever 20 is set to be larger than the length of the portion (inner portion) opposite to the pin receiving hole 20a from the shaft 19. Has been. Thus, the movement amount of the shutter member 14 is increased when the pair of levers 20, 20 that are link members rotate about the shafts 19, 19.

  On the other hand, a motor 59 as a shutter drive source is mounted via a bracket 62 on a face plate 58 that is a member on the image forming apparatus main body side. A shaft 60 rotated by the motor 59 protrudes from the upper surface of the bracket 62, and an eccentric cam 61 is fixed to the rotating shaft 60. The eccentric cam 61 rotates the disk member at a non-center position of the disk. Due to the rotation of the motor 59, the eccentric cam 61 rotates so as to include a position indicated by a solid line and a position indicated by an imaginary line in FIG. The face plate 58 is provided with a hole through which the eccentric cam 61 can protrude toward the optical scanning device 15, and the side surface of the eccentric cam 61 abuts against one lever 20 (in this example, the right lever 20 in FIG. 4). Has been. As shown in FIG. 5, the end portion of the lever 20 on one side (the contact portion with the eccentric cam 61) is bent vertically downward so that the lever and the eccentric cam 61 are in contact with each other to disperse the sliding resistance. Thus, the operation of the lever and the eccentric cam is stabilized, and partial wear of the lever 20 and the eccentric cam 61 is prevented.

  And the lever end of the other side (the left lever 20 in FIG. 4 in this example) is not bent, and the planar lever end is the side surface of the bent portion of the right lever 20 end (described above). It is in contact with the upper surface in FIG. In this example, the two levers are not moved in contact with the eccentric cam 61, but the other lever is moved via one lever, and the end of one lever in that case is bent. Accordingly, the two levers 20 moved by the eccentric cam 61 are prevented from interfering with each other and can be operated stably.

  Now, as the eccentric cam 61 rotates, the side surface of the eccentric cam 61 presses the inner ends of the levers 20 and 20, and the levers 20 and 20 rotate about the shafts 19 and 19. Thereby, as described above, the shutter member 14 is moved in the vertical direction in FIG. 4 (longitudinal direction of the optical scanning device 15: direction of arrow A in FIG. 1).

  When the eccentric cam 61 moves to the position indicated by the solid line in FIG. 4, that is, when the eccentric cam 61 is retracted to the inside of the face plate 58 (on the side opposite to the optical scanning device 15), the pressing of the levers 20 and 20 by the eccentric cam 61 is released. Therefore, the levers 20 and 20 biased by the torsion coil springs 21 and 21 rotate to the position shown in FIG. 4 (the position indicated by the solid line in FIG. 3), and the shutter member 14 is in the closed position shown in FIG. Moved to.

  When the eccentric cam 61 moves to the position indicated by the phantom line in FIG. 4, that is, when the eccentric cam 61 protrudes outside the face plate 58 (on the optical scanning device 15 side), the eccentric cam 61 biases the torsion coil springs 21 and 21. Against this, the levers 20 and 20 are rotated to the positions indicated by phantom lines in FIG. 3, and the shutter member 14 is moved to the open position shown in FIG.

  In the normal state (during non-image formation), the eccentric cam 61 is in the position shown by the solid line in FIG. 4. At this time, the shutter member 14 is held in the shutter closed position by the urging force of the torsion coil springs 21 and 21. When an instruction to shift to a writable state is issued during image formation, the motor 59 is driven (rotated by a predetermined amount), and the eccentric cam 61 rotates by a predetermined amount to open the shutter.

  In the optical scanning device 15 of this example, the shutter member 14 is urged in the closing direction by the urging means (here, the torsion coil spring 21). A certain dust-proof glass 8a, 8b, 8c, 8d portion can be protected, and contamination due to adhesion of toner, dust, etc. to the dust-proof glass can be minimized. Therefore, it is possible to continuously maintain a good image without causing streaks or unevenness in the formed image. In addition, it is possible to minimize the situation in which the dustproof glasses 8a, 8b, 8c, and 8d have to be cleaned.

  The state before the optical scanning device 15 is assembled to the main body of the image forming apparatus or when the optical scanning device 15 is removed from the main body of the image forming apparatus by the biasing means being biased in the closing direction. For example, the shutter member 14 is held in the shutter closed position. Therefore, the dust-proof glass 8a, 8b, 8c, and 8d portions are not used when the optical scanning device 15 needs to be replaced for repair or the like in the factory, or when the optical scanning device 15 is transported. Since it is covered with the shutter member 14 and is not exposed to the outside, it is possible not only to prevent dust from adhering to the dust-proof glass, but also to prevent the dust-proof glass from being damaged or damaged due to a work mistake or the like. It becomes possible to protect the optical scanning device.

  When the optical scanning device 15 is mounted on the main body of the image forming apparatus, it is arranged so that the inner ends of the levers 20 and 20 are in contact with the side surface of the eccentric cam 61 as described above, and the eccentric cam 61 is rotated by the motor 59. As a result, the shutter is opened and closed.

  By the way, the operation of the shutter member 14 must be reliably controlled to a shutter closed position that shields a laser beam that is scanning light and a shutter open position that allows passage of the laser beam. Therefore, in this example, a configuration for detecting that the shutter member 14 is in the closed position or the open position is provided.

  That is, as shown in FIG. 3, a bracket 63 is attached to the side surface of the face plate 58 opposite to the optical scanning device 15. A detection lever 64 is rotatably supported on the bracket 63 by a shaft 65. One end of the detection lever 64 is bent vertically upward, and the bent portion comes into contact with the side surface of the eccentric cam 61. A sensor 66 is provided in the vicinity of the opposite end of the detection lever 64. In this example, the sensor 66 includes two photo interrupters 67 and 68, and is supported on the face plate 58 via a bracket. The opposite end (the end opposite to the eccentric cam 61) of the detection lever 64 is a feeler (detected portion) detected by the sensor 66, and the lever end is a photo interrupter 67, 68. Is closed, the closed position or the open position of the shutter member 14 is detected.

  A torsion coil spring (not shown) is fitted to the shaft 65 that supports the detection lever 64, and the torsion coil spring causes the detection lever 64 to rotate clockwise in FIG. 3 (the lever bent portion is brought into contact with the eccentric cam 61. In the direction). In the shutter closed state of the eccentric cam 61 indicated by the solid line in FIGS. 3 and 4, the detection lever 64 is pressed by the eccentric cam 61 and the feeler blocks the photo interrupter 67. 3 and FIG. 4, in the shutter open state of the eccentric cam 61, the pressing force of the eccentric cam 61 is released, the torsion coil spring rotates the detection lever 64 to the position of the phantom line, and the feeler The photo interrupter 68 is blocked. Therefore, in this example, it is detected that the shutter member 14 is in the closed position due to the output of the photo interrupter 67 being off, and that the shutter member 14 is in the open position due to the output of the photo interrupter 68 being off. The shutter drive motor 59 is controlled based on the output of the sensor 66 (photointerrupters 67 and 68), and the drive and stop control are appropriately performed.

  As described above, in this example, the state of the eccentric cam 61 which is a member constituting the shutter driving means is detected by the sensor 66 via the detection lever 64, whereby the position of the shutter member 14 (the open / close state of the shutter is determined). It is possible to reliably obtain the closed state and the open state of the shutter by accurately detecting and thereby controlling the drive and stop of the motor 59 which is the shutter drive source.

  In general, the space in the actual image forming apparatus in which the writing unit as the optical scanning device is arranged is narrow, and it is difficult to take a long movement stroke of the shutter member. Therefore, it is necessary to maintain the positions of the shutter member in the light path blocking state and the non-blocking state with high accuracy. In this example, as described above, the torsion coil spring 21 is used as the urging means for urging the shutter member 14 toward the closed position, and the torsion coil spring 21 is provided on the upper cover 11 of the optical housing. Therefore, the shutter member 14, the levers 20 and 20 that are link members, and the torsion coil springs 21 and 21 that are urging members are arranged on the upper cover 11 of the same member, so that the mutual positional relationship is kept with high accuracy. Thus, the positions of the shutter member in the light path blocking state and the non-blocking state can be accurately maintained.

  In this example, as a biasing means for biasing the shutter member 14 in the closed position direction, a torsion coil spring 21 mounted on a shaft 19 that is a pivotal fulcrum of the lever 20 that is a link member is used. In this case, the degree of freedom in design with respect to the location and shape of the shutter member urging means is slightly reduced, but the force point for moving the shutter member can be limited to the shaft 19, so that the shutter member 14 The shutter member 14 can be smoothly and stably moved without applying an unexpected moment. If the tension spring or compression spring is directly locked to the shutter member, the balance with the link member may be poor depending on the position of the spring, and a moment that adversely affects the linear movement of the shutter member is generated. There is a case. However, in this example, no extra moment is generated, and the shutter member can be moved stably.

  Incidentally, as shown in FIG. 5, a plurality of (many) reinforcing ribs extending in the longitudinal direction of the housing are projected on the upper surface of the upper cover 11 of the optical housing. In this example, the shutter guide portion 24 is provided on an appropriate number (12 in this example) of the plurality of reinforcing ribs. The shutter guide portion 24 is provided with a part of the reinforcing rib extending upward from the other part and having a high (large) height. As described above, the shutter member 14 is not lifted by the stepped screw 17 (FIG. 3) and is mounted on the upper cover with an appropriate interval necessary for sliding, but is provided on the upper surface of the upper cover 11. It is slidably supported on a predetermined number (12 in this example) of shutter guide portions 24. As described above, the shutter member 14 is supported by the thin rib-shaped shutter guide portion 24 that extends in the moving direction of the shutter member 14, thereby suppressing the sliding resistance of the shutter member 14 and the shutter member 14. Stable movement is possible.

  And as shown in FIG. 6, the part surrounding the dust-proof glass 8 mounting part of the upper cover 11 is raised upwards, and the upright part 11a is formed. As a result, when the shutter member 14 is in the closed state, the shutter member 14 and the raised portion 11a are close to each other, and there is almost no gap between them, thereby preventing the entry of toner or dust.

  In this embodiment, a link mechanism is employed as a movable member that moves the shutter member 14. In the link mechanism, the shutter member 14 is a driven member that is moved by the link mechanism, the levers 20 and 20 are link members, and the eccentric cam 61 drives the levers 20 and 20 together with a motor 59 as a drive source. Means. In the link mechanism having such a configuration, the levers 20 and 20 are pivotally supported around the shafts 19 and 19 as described above. The positions of the shafts 19 and 19 (positions of the rotation fulcrums of the levers 20 and 20) are provided closer to the eccentric cam 61 side which is an operating member than the center of the lever 20. Thereby, the movement amount of the eccentric cam 61 which is a drive means can be expanded and transmitted to the shutter member 14.

  That is, as described above, the amount of movement of the shutter member 14 when the pair of levers 20 and 20 rotates about the shafts 19 and 19 is increased. For example, when the ratio of the length of the outer portion (distance to the pin receiving hole 20a) and the inner portion (distance to the contact portion with the eccentric cam 61) of the lever 20 around the shaft 19 is 2: 1, The shutter member 14 can be moved by a distance that is approximately twice the distance of the eccentric cam 61 in the A direction (see FIGS. 3 and 4). As described above, the space in the actual image forming apparatus in which the optical scanning device is installed is narrow, and there may be a case where the moving amount (eccentric amount) of the eccentric cam 61 which is a member constituting the driving unit cannot be sufficiently secured. Even when a drive mechanism having a configuration different from that of the present example is used, there may be a case where the stroke of the drive means or the operation means cannot be secured sufficiently. However, by using the link member as described above and providing the fulcrum on the drive means side with respect to the center of the link member, it is possible to obtain a necessary amount of movement of the shutter member in a narrow space.

  Although it is possible to move the shutter member 14 directly by the driving means actuating means without using the link member as in another embodiment described later, the shutter member 14 is moved via the link mechanism as in this embodiment. By doing so, there is an advantage that the design margin with respect to the moving direction and moving stroke of the shutter can be increased.

  In this embodiment, as described above, one end of the pair of levers 20 and 20 is bent, and the end of the other lever 20 is in contact with the bent portion (see FIG. 5). Accordingly, when one lever 20 (on the side having the bent portion) is pushed by the eccentric cam 61 which is an operating member, the other lever 20 is pushed in conjunction with the one lever 20, and as a result, 1 The pair of levers 20 and 20 are simultaneously driven by the same amount. This makes it possible to equalize the drive timing, drive force, and drive stroke for the pair of levers 20, 20 that are link members, and smooth the shutter member 14 without applying an unexpected moment to the shutter member 14. Can be moved stably and repeatedly.

  By the way, in the present embodiment, of the mechanism for moving the shutter member, the driving means (the motor 59 and the eccentric cam 61 as a driving source) are arranged on the image forming apparatus main body side. Thereby, the cost and weight of the unit of the optical scanning device 15 can be reduced. Therefore, when the optical scanning device is replaced after shipment as an image forming device, it is advantageous in terms of cost and workability. Further, when the optical scanning device 15 is attached / detached, it is not necessary to attach / detach the harness of the driving unit, and the optical scanning device 15 does not need to directly mount the driving unit serving as a vibration source. Adverse effects can be avoided.

  On the other hand, it is possible to mount the driving means on the optical scanning device. Although not shown, in the case where the driving means is mounted on the optical scanning device, the accuracy of each component of the mechanism for moving the shutter member can be kept high, and the shutter member can be opened and closed with higher accuracy. Is possible. Whether the driving means is mounted on the optical scanning device or disposed on the main body side of the image forming apparatus should be appropriately considered depending on the layout of the system.

  In the present embodiment, the sensor 66 that detects the open / closed state of the shutter member 14 indicates the movement of the eccentric cam 61 as a driving means (one of the members constituting the mechanism for moving the shutter member) (the detection lever 64 is operated). To detect). However, the present invention is not limited to this, and a configuration in which the motor 59 or the eccentric cam 61 is directly detected or the movements of the levers 20 and 20 as other members are detected by a sensor is also possible.

  Furthermore, a configuration in which a part of the shutter member 14 is directly detected is also possible. For example, as shown in FIG. 7, a detected portion 25 may be provided in a part of the shutter member 14 and the detected portion 25 may be detected by a sensor 66. In this configuration example, the sensor 66 is disposed on the upper cover 11 of the optical housing. As the shutter member 14 reciprocates in the direction A in FIGS. 2 and 3, the detected portion 25 blocks the photo interrupter of the sensor 66 at the shutter closed position, and the detected portion 25 comes out of the sensor 66 when the shutter is opened. Therefore, the open / close state of the shutter can be detected based on the output of the sensor 66.

  When a sensor for detecting the open / close state of the shutter is mounted on the optical scanning device side, the movement of the shutter member can be directly detected, so that highly accurate detection is possible. On the other hand, the cost of the optical scanning device itself, which can be considered as a service unit, is increased, and there is a disadvantage that the handling of a harness (necessary for sending the sensor output to the main body) when attaching and detaching the optical scanning device becomes complicated. Therefore, an optimal method for the system may be appropriately selected as to whether the sensor for detecting the opening / closing state of the shutter is arranged on the image forming apparatus main body side or mounted on the optical scanning apparatus side.

  FIG. 8 shows another example in which a tension spring is used as the urging means for urging the shutter member 14. In the illustrated example, a tension spring 28 is locked between the shutter member 14 and the upper cover 11 of the optical housing. When the shutter member 14 is moved in the A1 direction from the shutter closed position shown in the drawing and the shutter is opened, the tension spring 28 is pulled by the shutter member 14. Therefore, the shutter member 14 is urged by the tension spring 28 in the direction of closing the shutter. In the case of this configuration, the tension spring 28 is locked at a position in consideration of the balance with the levers 20 and 20 that are link members so as not to generate a moment that adversely affects the linear movement of the shutter member 14. .

  FIG. 9 is a schematic diagram showing a configuration example in which the shutter member 14 </ b> B is directly driven by the eccentric cam 61. In the illustrated example, the shutter member 14B that is in direct contact with the eccentric cam 61 is linearly moved in the direction of arrow B in accordance with the movement of the eccentric cam 61 that is rotationally driven by a motor.

  There are other methods for converting the rotation of the motor as the drive source into a linear movement of the shutter member. In the example shown in FIG. 10, a roller-attached rod 26 having a roller at the tip is attached to the shutter member 14C, and is urged rightward in the drawing by an urging means (not shown). The roller of the roller rod 26 is in contact with the inclined surface of the conversion member 70. When the conversion member 70 having a slope obtained by obliquely cutting the cylinder is rotated by the motor 69, the shutter member 14C is linearly moved in the direction of arrow C.

  In the example shown in FIG. 11, a rack member 27 having a rack at the tip is attached to the shutter member 14D. The rack of the rack member 27 is meshed with a gear 71 rotated by a motor 69. By rotating the motor 69 forward and backward, the shutter member 14D is linearly moved in the direction of arrow D.

  In the example shown in FIG. 12, a pin 73 is protruded at a position off the center of the disk 72 rotated by the motor 69. The shutter member 14E is urged to the right in the figure by an urging means (not shown) so as to abut against the pin 73. When the disk 72 is rotated by the motor 69, the shutter member 14E is linearly moved in the direction of arrow E.

  In such a configuration without the link member, restrictions on the shutter stroke occur compared to the configuration in which the shutter member is moved through the link member described above, but the number of parts can be reduced, and the configuration is simple. A low-cost configuration can be obtained. An appropriate configuration can be selected according to specifications, device layout, and the like required from the image forming apparatus system.

  When the driving means for driving the shutter member is arranged on the image forming apparatus main body side, it is preferable to arrange the driving means at a portion between the optical scanning device and the paper feed path.

  In general, the optical scanning device is generally attached and detached on the opposite side of the paper feed path or on the front side of the device. For this reason, the installation location of the driving means for driving the shutter member may be between the optical scanning device on the rear side in the attaching / detaching direction of the optical scanning device and the paper feed path, or the back side of the device so as not to disturb the attachment / detachment. . However, the space on the back side of the image forming apparatus is limited by the drive system of the main body device, and the arrangement becomes complicated if the drive means is arranged at a position perpendicular to the shutter moving direction, and the design is free. For example, it is optimal to place the drive means in a portion between the optical scanning device and the paper feed path. Also in this embodiment, as is clear from FIGS. 1 to 3, a motor 59 or the like is disposed between the optical scanning device 15 and the paper feeding path from the paper feeding unit 52 (on the right side of the optical scanning device 15 in FIG. 1). An eccentric cam 61 and the like are arranged.

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. For example, the conversion mechanism that converts the rotational motion of the motor into linear motion and moves the shutter member is not limited to the eccentric cam, and a normal cam made of a non-disk member may be used. Moreover, when using a link mechanism, the shape of a link member, the position of a fulcrum, etc. can be set suitably. In addition, as the configuration of each part of the optical scanning device, an appropriate configuration can be adopted within the scope of the present invention. In an image forming apparatus equipped with an optical scanning device, the method of the image forming unit and the configuration of each part of the device are arbitrary. Further, the image forming apparatus is not limited to a printer, and may be a copier, a facsimile, or a complex machine thereof.

1 is a cross-sectional configuration diagram illustrating an outline of an image forming apparatus including an example of an optical scanning device according to the present invention. It is an enlarged view which shows the optical scanning device vicinity in detail. It is a perspective view which shows an optical scanning device and its shutter drive mechanism. It is a fragmentary top view which shows the link member vicinity of a shutter drive mechanism. It is a perspective view which shows the upper cover of an optical housing. It is sectional drawing of dust-proof glass mounting part vicinity. It is a perspective view which shows typically another structural example which detects the opening / closing state of a shutter. It is a perspective view which shows another example of the shutter urging means using a tension spring. It is a schematic diagram which shows another example of a shutter moving mechanism. It is a schematic diagram which shows another example of a shutter moving mechanism. It is a schematic diagram which shows another example of a shutter moving mechanism. It is a schematic diagram which shows another example of a shutter moving mechanism.

Explanation of symbols

8 Dust-proof glass 11 Upper cover 13 Optical housing 14 Shutter member 15 Optical scanning device 16 Guide groove 17 Stepped screw 18 Shutter opening 20 Lever (link member)
21 Torsion coil spring (shutter biasing means)
50 Full color printer 58 Face plate 59 Motor 61 Eccentric cam 64 Detection lever 66 Sensor

Claims (9)

In an optical scanning device that scans a surface to be scanned by emitting a light beam from a light source through an exit window of an optical housing,
A shutter member for shielding and opening the exit window;
The shutter member is urged by urging means in a direction to shield the exit window, and the shutter member is moved via one link mechanism including a pair of lever members,
The link mechanism is configured such that one lever member operated by the driving means operates the other lever member ,
An end portion of the one lever member is bent to form a flat portion, and the flat portion is driven by being brought into contact with the driving means, and the end portion of the other lever member is the one of the one lever member. An optical scanning device that is driven through a flat surface portion . In the link mechanism, the force point by the driving means is in the central portion in the longitudinal direction of the exit window, and the action point at which each lever member acts on the shutter member is in the vicinity of both end portions in the direction perpendicular to the moving direction of the shutter member. The optical scanning device according to claim 1, wherein the optical scanning device is provided. 3. The optical scanning device according to claim 2 , wherein a length from the pivot point of the lever member to the action point is set larger than a length from the force point to the pivot point. Characterized in that said biasing means for biasing said lever member, an optical scanning apparatus according to any one of claims 1-3. The optical scanning device according to claim 4 , wherein the urging unit is a torsion coil spring mounted on a rotation shaft of the lever member. The optical scanning device according to claim 1, wherein the optical housing is provided with a plurality of shutter guide portions that extend in the moving direction of the shutter member and support the shutter member. The optical scanning device according to claim 6 , wherein the shutter guide portion is formed in a thin rib shape. The optical scanning device according to claim 1, wherein the optical scanning device includes a plurality of the exit windows, and the shutter member is a member that integrally shields and opens the plurality of exit windows. An image forming apparatus comprising the optical scanning apparatus according to any one of claims 1-8.

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