JP2013010285A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a cleaning device for cleaning a dust proof glass from interrupting an optical path of light for forming an electrostatic latent image.SOLUTION: After the cleaning of the dust proof glass is completed, a control unit negatively turns a clutch 61 by an angle θ and brings a solenoid 62 into a state of non-energization (OFF state) (step S15). As a result, a claw 621 is changed into a locking position. Afterwards, when the control unit positively turns the clutch 61, a protrusion 611 is engaged with the claw 621, and thereby the clutch 61 and an eccentric cam 52 stop at a reference position.

Description

  The present invention relates to an image forming apparatus including an optical scanning unit that irradiates an image carrier with light based on image data, and a cleaning device that cleans a transmission window that transmits light provided in an exposure apparatus.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a photosensitive drum by irradiating a charged photosensitive drum with laser light based on image data. The laser light is emitted toward a photosensitive drum from a laser scanning unit (hereinafter referred to as “LSU (Laser Scanning Unit)”) in which optical devices such as a light source, a polygon mirror, an fθ lens, and a deflection mirror are incorporated. The electrostatic latent image formed on the photosensitive drum by the laser beam emitted from the LSU is visualized as a toner image by supplying toner by the developing device, and the toner image is transferred and fixed on the paper. The printing is performed by.

  By the way, the toner supplied from the developing device to the photosensitive drum is peeled off from the photosensitive drum during the supply process, when the photosensitive drum rotates, or when the residual toner attached to the surface of the photosensitive drum is collected. May float inside the forming device. Therefore, in order to prevent the toner from entering the inside of the LSU, a transmissive dustproof glass is generally provided at the exit from which the laser beam is emitted from the LSU. In particular, when the LSU is disposed below the photosensitive drum, there is a high possibility that the toner peeled from the photosensitive drum enters the LSU, and thus a dust-proof glass that closes the emission port is necessary.

  Providing the dust-proof glass in this way can prevent the toner from entering the LSU, but the toner falls and adheres to the surface of the dust-proof glass. When dust such as toner adhering to the dustproof glass obstructs the optical path of the laser beam, there arises a problem that an accurate electrostatic latent image cannot be drawn on the photosensitive drum.

  Therefore, a cover with dust-proof glass is slidably attached to the top of the LSU, and when irradiating the photosensitive drum with laser light, the cover is slid so that the dust-proof glass is positioned on the optical path of the laser light, and cleaning is performed during standby. Patent Document 1 discloses an image forming apparatus capable of cleaning dust-proof glass by holding the brush in contact with dust-proof glass and moving the cleaning brush by a user or a service person.

JP 2009-148979 A

  However, with the technique described in Patent Document 1, the final cleaning of the dustproof glass is not performed unless the cleaning brush is moved by a human hand. Therefore, it is troublesome and inconvenient for users and service personnel.

  In addition, a cleaning device that automatically cleans the dust-proof glass using a transport roller that transports the paper as a drive source has been proposed, but there is a method of covering the cleaning device with a film member made of polyethylene as a dust-proof measure of the cleaning device. . However, the protrusions of the parts that make up the cleaning device come into contact with the film-like member, and after cleaning, the dust-proof removal member that cleans the dust-proof glass does not fit well in the standby position and is dust-proof removed during printing (when laser light is emitted). There is a problem that the member blocks the optical path of the laser beam.

  The present invention has been made to solve the above-described problem, and an object thereof is to provide an image forming apparatus including a cleaning device that automatically cleans dust-proof glass without blocking the optical path of laser light. To do.

  An image forming apparatus according to a first aspect of the present invention includes an image carrier that carries an electrostatic latent image, an exposure unit that emits light based on image data toward the image carrier, and the exposure unit that includes And a housing having a transmission window that transmits light emitted from the exposure means, an eccentric cam that is rotationally driven by a driving force transmitted from a driving source, and a protrusion on a part of the outer periphery. A clutch for switching presence / absence of transmission of driving force from a source to the eccentric cam, and a claw that engages with the projection, and the clutch is stopped at a reference stop position by engaging the claw with the projection. A driving means having a stopping means, a dust removing means for removing dust adhering to the transmission window by sliding on the surface of the transmission window, and a driving force of the driving means to the dust removal means. Transmit the dust A transmission means for sliding the means; a film-like member interposed between the drive means and the cleaning means; and controlling the operation of the clutch. Drive control means for switching between an engagement position that engages with the protrusion and a non-engagement position that does not engage, and after the cleaning of the transmission window by the cleaning means, the drive control means The claw claw is switched to the non-engagement position with respect to the stop means, and the clutch is rotated in reverse at a predetermined angle, and then the claw claw is switched to the engagement position with respect to the stop means. By rotating the clutch forward, the clutch is stopped at the reference stop position.

  In some cases, the protruding portion of the clutch is caught on the film-like member due to a change in the position or shape of the film-like member, and the clutch does not stop at the reference stop position. When stopping at a position other than the reference stop position, the projection and the claw are not engaged, so the clutch easily rotates by some force applied from the outside, and the cleaning of the transmission window by the dust removing means is at an unexpected timing. Sometimes it was done. If this cleaning is performed during exposure by the exposure means, the light transmitted through the transmission window is blocked, and a correct electrostatic latent image cannot be formed on the image carrier, and correct printing cannot be performed.

  Therefore, after the cleaning of the transmission window by the cleaning means is completed, the clutch is reversely rotated by a predetermined angle under the control of the drive control means, and then forwardly rotated, whereby the protrusion and the claw can be engaged. it can. The engagement between the projection and the claw means that the clutch stops at the reference stop position, and it is possible to prevent a situation in which the driving means starts to move during exposure and the transmission window is cleaned.

  The clutch according to the present invention normally transmits a driving force to the eccentric cam when the driving source is rotating forward, but rotates idly when a force exceeding a predetermined torque is applied to the projection or the like (that is, driving of the driving source). Force is not transmitted to the eccentric cam). Further, during reverse rotation, the driving force is transmitted to the eccentric cam.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the predetermined angle is a range in which the protrusion is located at a position facing the film-like member. The angle is greater than the angle formed by the position farthest from the engagement position and the engagement position.

  By doing so, it is possible to move the protrusion so that it comes closer to the front side during forward rotation than the position of the protrusion when the clutch is in the reference stop position. Thereafter, by rotating the clutch 61 forward, it can be engaged with the claw 621 at the position of the protrusion 611a.

  A third aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the drive control means has a slower speed than the forward rotation when the clutch is reversely rotated by the predetermined angle. Rotate with.

  By making the rotation speed at the time of reverse rotation slower than that at the time of normal rotation, the inertial rotation time of the drive source is shortened, so that the accuracy of the stop position of the drive source can be increased and the accuracy of the stop position of the clutch is also increased. Can do.

  According to the present invention, the clutch can be surely stopped at the reference stop position, the driving means starts moving during exposure, the transmission window is cleaned, and the light for forming the electrostatic latent image is blocked. Can be prevented.

FIG. 2 is a cross-sectional view schematically illustrating an image forming apparatus. The schematic block diagram of a LSU main-body part and a top cover. The perspective sectional view showing a part of cleaning device and a drive unit. Front sectional drawing which showed a cleaning apparatus and a part of drive device. The external view when a part of cleaning device is seen from the top. The perspective view when the housing | casing which provided the drive device inside is seen from the upper surface lid side. Front sectional drawing which showed a cleaning apparatus and a part of drive device. Front sectional drawing which showed a cleaning apparatus and a part of drive device. Front sectional drawing which showed a cleaning apparatus and a part of drive device. Front sectional drawing which showed a cleaning apparatus and a part of drive device. The flowchart which showed the flow of control with respect to the drive device by a control part. The figure which showed the change of the signal waveform of the motor remote signal at the time of reverse rotation, and the rotational speed of DC motor. The figure which showed the change of the signal waveform of the motor remote signal at the time of reverse rotation, and the rotational speed of DC motor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a color printer is described as an example of the image forming apparatus, but a monochrome printer may be used. The present invention can be applied to any image forming apparatus having an LSU that irradiates a photosensitive drum with laser light through a transmission window. Therefore, in addition to a printer, a copier, a facsimile machine, A multifunction machine or the like having a function may be used.

  FIG. 1 is a sectional view schematically showing an image forming apparatus 1 according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the LSU 6. The configuration of the image forming apparatus 1 will be described with reference to FIGS. 1 and 2.

  The image forming apparatus 1 is a tandem color printer including image forming units 2 (2M, 2C, 2Y, and 2K) for each color of magenta (M), cyan (C), yellow (Y), and black (K). is there. Each of the image forming units 2M, 2C, 2Y, and 2K includes a photosensitive drum 4, a developing device 3, a charger 5, an LSU 6, a toner supply unit 7, a cleaner 21, and a primary transfer roller 9.

  The toner supply unit 7 stores magenta, cyan, yellow, and black toners. The developing device 3 includes a developing roller 39 for supplying the toner supplied from the toner supply unit 7 to the photosensitive drum 4.

  The developing roller 39 includes, for example, a cylindrical developing sleeve whose surface is made of a nonmagnetic material such as aluminum. A magnet material or the like is disposed inside the developing sleeve. The developer composed of toner and carrier in the developing device 3 is attracted to the surface of the developing roller 39 by the magnetic force of the magnet material, and the developing roller 39 rotates in a predetermined direction, so that only the toner of the developer is a photoreceptor. Move to the surface of the drum 4.

  The photosensitive drum 4 is located below a transfer belt 8 described later and is disposed in contact with the outer surface of the transfer belt 8. From the upstream side in the rotation direction B of the transfer belt 8, a magenta photosensitive drum 4, a cyan photosensitive drum 4, a yellow photosensitive drum 4, and a black photosensitive drum 4 are arranged in parallel. The photosensitive drum 4 is made of a-Si (amorphous silicon) or the like and rotates in the clockwise direction (A direction in the figure) in FIG.

  A primary transfer roller 9 is disposed through the transfer belt 8 in a state where the primary transfer roller 9 is in contact with the inner surface of the transfer belt 8 at a position facing the photosensitive drum 4. The primary transfer roller 9 is a roller that is driven to rotate by the rotation of the transfer belt 8, nips the transfer belt 8 with the photosensitive drum 4, and transfers the toner images of the respective colors formed on the photosensitive drum 4 to the transfer belt 8. A primary transfer portion T for primary transfer is configured. In the primary transfer portion T, the toner images of the respective colors are transferred onto the transfer belt 8 in a multiple manner. As a result, a color toner image is formed on the transfer belt 8.

  The charger 5 uniformly charges the peripheral surface of the photosensitive drum 4. The LSU 6 includes a polygon mirror 28 that guides laser light based on image data transmitted from an external device to the peripheral surface of the photosensitive drum 4. The polygon mirror 28 scans the circumferential surface of each photosensitive drum 4 in the main scanning direction while rotating by a polygon motor (not shown) to form an electrostatic latent image on each circumferential surface. The main scanning direction is a direction in which laser light is scanned in the longitudinal direction of the photosensitive drum 4. In FIG. 1, the polygon mirror 28 is shared between the plurality of photosensitive drums 4.

  The developing device 3 supplies toner to the photosensitive drum 4. As a result, toner adheres to the electrostatic latent image, and a toner image is formed on the photosensitive drum 4.

  The cleaner 21 is disposed on the peripheral surface of each photosensitive drum 4 and removes residual toner and the like on the peripheral surface.

  The transfer belt 8 is arranged above the row of the photosensitive drums 4 and is stretched between the driven roller 10 and the driving roller 11 so that the outer surface is in contact with the peripheral surface of the photosensitive drum 4. It is installed. Further, the transfer belt 8 is urged upward by a tension roller 19. The driving roller 11 rotates in response to a driving force from a driving source (not shown) to drive the transfer belt 8 to rotate. The driven roller 10 is driven to rotate by the rotation of the transfer belt 8. As a result, the transfer belt 8 rotates in the B direction (counterclockwise direction).

  Further, the transfer belt 8 is in a state where a portion wound around the driving roller 11 is bent, and the toner image primarily transferred to the transfer belt 8 is secondarily transferred to the paper P in this bent portion. Secondary transfer position P1. At the secondary transfer position P1, a secondary transfer roller 18 facing the driving roller 11 with the transfer belt 8 interposed therebetween is provided. The secondary transfer roller 18 forms a nip with the driving roller 11, and secondarily transfers the toner image on the outer surface of the transfer belt 8 onto the paper P passing through the nip.

  A pair of registration rollers 17 is disposed below the secondary transfer position P1. The registration roller 17 transports the paper P toward the secondary transfer position P1 at an appropriate timing and corrects the oblique feeding of the paper P.

  Above the secondary transfer position P1, there is provided a fixing device 14 that performs a fixing process on the paper P on which the secondary transfer of the toner image has been performed at the secondary transfer position P1. The fixing device 14 includes a heating roller 14a and a pressure roller 14b, and this pair of rollers forms a fixing nip portion NP. When the paper P passes through the fixing nip NP, the heating roller 14a heats the paper P, and the pressure roller 14b presses the paper P, so that the second-transferred toner image is fixed on the paper P. To do.

  After the fixing process is performed at the fixing nip portion NP, the paper P may be wound around the heating roller 14a. In this case, inconvenience such as paper jam occurs. In order to eliminate such inconvenience, a separation claw member is provided in the fixing device. This separation claw member will be described in detail later.

  A sheet feeding cassette 12 that stores a bundle of sheets is disposed below the LSU 6. Between the paper feed cassette 12 and the secondary transfer position P1, a paper transport path 13 for guiding the paper P from the paper feed cassette 12 to the secondary transfer position P1 is provided. The registration roller 17 described above is disposed in the sheet conveyance path 13. In addition to the registration rollers 17, a plurality of roller pairs for guiding the paper P are disposed at appropriate positions in the paper transport path 13.

  The heating roller 14 a and the pressure roller 14 b convey the paper P toward the discharge roller pair 151 after passing through the fixing nip NP. On the upper surface of the image forming apparatus 1, a discharge unit 16 that discharges the paper P that has been subjected to the fixing process by the fixing device 14 is formed, and between the discharge unit 16 and the fixing device 14, the paper P Is provided with a paper discharge path 15. The paper P is conveyed to the paper discharge path 15 by driving the discharge roller pair 151 and is discharged to the discharge unit 16.

  Next, the LSU 6 will be described in detail. FIG. 2 is a schematic configuration diagram of the LSU main body portion 31 and the upper surface lid 33 of the LSU 6, and the broken lines shown in the drawing indicate the assembly corresponding positions of the LSU main body portion 31 and the upper surface lid 33. 3 is a perspective sectional view showing a part of the cleaning device 40 and the driving device 50, and FIG. 4 is a front sectional view.

  The LSU main body 31 incorporates optical devices such as a light source 301, a deflection mirror 302, a polygon mirror 28, and various optical lenses. The upper surface lid 33 is formed with an emission port 303 (303BK, 303M, 303Y, and 303C) through which laser light emitted from the light source 301 is emitted from the LSU (see partially enlarged view A). Further, in order to prevent dust such as toner from entering the LSU main body 31 from the exit port 303, each exit port 303 is covered with dust-proof glass 304 (304BK, 304M, 304Y and 304C) that transmits laser light. (See partially enlarged view A). Accordingly, the laser light emitted from the light source 301 passes through the dust-proof glass 304 covering the emission port 303 and is irradiated on the photosensitive drum 4.

  When the LSU 6 is disposed below the photosensitive drum 4 and the developing device 3, the toner is peeled off when the photosensitive drum 4 rotates or when the toner moves from the developing device 3 to the photosensitive drum 4. 1 may float inside. The peeled toner is highly likely to fall on the LSU 6 below. When the dropped toner adheres to the dustproof glass 304, the laser beam is blocked by the toner, and the laser beam is not normally irradiated to the photosensitive drum 4. That is, the toner image is not accurately formed, and the image quality is deteriorated.

  For this reason, the upper surface lid 33 is integrally provided with a cleaning device 40 for cleaning the dust-proof glass 304. The cleaning device 40 according to the present embodiment is configured integrally with the upper surface lid 33 of the LSU 6, but is not limited thereto, and an example in which the cleaning device 40 is configured separately from the upper surface lid 33 and mounted on the upper portion of the LSU 6 is also considered. It is done.

  The cleaning device 40 includes a cleaning blade 41 (41BK, 41M, 41Y and 41C) for cleaning the dustproof glass 304, a holding member 42 (42BK, 42M, 42Y and 42C) for holding the cleaning blade 41, and both end portions of the holding member 42. By connecting the plurality of cleaning blades 41, the plurality of cleaning blades 41 are integrally connected to each other.

  The cleaning blade 41 is an elastic plate-like member formed in substantially the same length as the longitudinal direction (X direction) of the dust-proof glass 304, and is disposed in a state where one side thereof is in contact with the surface of the dust-proof glass 304. . As the cleaning blade 41 slides, the side of the cleaning blade 41 in contact with the dust-proof glass 304 rubs the surface of the dust-proof glass 304, and the toner attached to the surface of the dust-proof glass 304 is removed. The cleaning blade 41 may be, for example, a brush or the like as long as it is a member that can remove dust such as toner by sliding in one direction on the surface of the dust-proof glass 304.

  The connecting member 43 is fitted in rail grooves 34 (34 a and 34 b) provided in the upper surface lid 33, and is slidable along the rail grooves 34. When a driving force is transmitted to the connecting member 43 from a driving device 50 described later, the cleaning device 40 slides along the rail groove 34, and the cleaning blade 41 connected by the connecting member 43 has a plurality of dustproof glasses 304. Slide all at once along the surface.

  The driving device 50 in the present embodiment presses the cleaning device 40 in one direction (arrow S) by rotating and receiving a driving force from the DC motor M and rotating and supported by the rotating shaft 51. Eccentric springs 52 (52a and 52b), and springs 53 (53a and 52b) for urging the connecting member 43 in a direction opposite to the direction in which the cleaning device 40 is slid by the eccentric cam 52 (in the direction of arrow R). 53b), a clutch 61 for switching presence / absence of transmission of driving force from the DC motor M to the rotating shaft 51, and a solenoid 62 for stopping the rotation of the eccentric cam 52.

  The eccentric cam 52 is an eccentric wheel in which a rotating shaft 51 serving as the center of rotational driving is inserted at a position deviated from the center point of a circle. The eccentric cam 52a and the eccentric cam 52b are respectively located at both ends of the rotating shaft 51. The eccentric cam 52a is connected to a clutch 61 described later, and rotates together with the clutch 61 when the clutch 61 is in a connected state. Then, the rotational motion of the eccentric cam 52 a is converted into the reciprocating motion of the connecting member 43.

  More specifically, the connecting member 43 is pressed and slid in one direction (arrow S direction) by the rotational drive of the eccentric cam 52a, and the spring 53 is compressed by the connecting member 43. Energize in the reverse direction (arrow R direction). Accordingly, the cleaning device 40 reciprocates by the amount of the deviation width between the center point of the eccentric cam 52a and the rotation shaft 51 as the eccentric cam 52a is driven to rotate.

  The deviation width between the center point of the eccentric cam 52 and the rotating shaft 51 is set to be approximately the same as the width of the dust-proof glass 304 in the short direction. Therefore, the dust-proof glass 304 is simultaneously cleaned by the reciprocating motion of the cleaning device 40 at this time, that is, the reciprocating motion of the cleaning blade 41. On the other hand, the eccentric cam 52 b rotates following the rotation of the rotating shaft 51.

  By the way, although the DC motor M is used as the rotation drive source of the rotation shaft 51, the DC motor M also serves as a drive source of a transport roller for transporting paper such as the secondary transfer roller 18 and the registration roller 17. In this case, the driving force is transmitted to the driving device 50 even when these transport rollers are rotationally driven. That is, the driving force is transmitted to the driving device 50 regardless of whether or not the dust-proof glass 304 is cleaned by the cleaning device 40, and there arises a problem that noise and the cleaning blade 41 are wasted.

  Therefore, the clutch 61 switches the presence / absence of transmission of the driving force from the DC motor M by switching connection / disconnection in accordance with control by the control unit 90. The control unit 90 outputs a motor remote signal for instructing rotation to the DC motor M, outputs a signal for instructing connection / disconnection to the clutch 61, and controls whether the solenoid 62 is energized or not energized. Output a signal.

  The control unit 90 outputs a control signal for connecting the clutch 61, for example, immediately after the image forming apparatus 1 is turned on or before and after printing. In response to this control signal, the clutch 61 is connected, the driving force is transmitted from the DC motor M to the eccentric cam 52a, and the dust-proof glass 304 is cleaned by the cleaning blade 41. As the clutch 61, for example, a one-way clutch that is driven to rotate only in one direction is used.

  The clutch 61 is connected to the eccentric cam 52a. The clutch 61 normally transmits its driving force to the eccentric cam 52a when the DC motor M is rotating forward. However, when the force exceeding a predetermined torque is applied to the eccentric cam 52a, the clutch 61 idles (that is, the DC motor M). The driving force is not transmitted to the eccentric cam 52a), and during reverse rotation, the driving force is transmitted to the eccentric cam 52a.

  The solenoid 62 is for stopping the clutch 61 and the eccentric cam 52a at the reference position (home position). The solenoid 62 is controlled to be energized / de-energized under the control of the control unit 90. For example, the claw 621 is switched to a dotted line position (non-locking position) when energized, and to a solid line position (locking position) when not energized. Change. A protrusion 611 is provided on the outer periphery of the clutch 61, and the solenoid 62 is adjusted and arranged so that the hook claw 621 and the protrusion 611 are engaged when the hook claw 621 is in the locking position. By engaging the claw 621 and the protrusion 611, the rotation of the clutch 61 is stopped, and the stop position of the eccentric cam 52a can be determined as the reference position.

  The clutch 61 and the eccentric cam 52a shown in FIG. 4 show a state stopped at the reference position. The position of the protrusion 611 is such that the eccentric cam 52a and the holding member 42 are not in contact with each other when the protrusion 611 and the claw 621 are engaged (when the clutch 611 is stopped at the reference position). It is desirable to be provided.

  The holding member 42 includes a shaft blade 42a that supports the cleaning blade 41 by being directly connected, and a support plate 42b that transmits the rotational drive of the eccentric cam 52a to the shaft blade 42a. FIG. 5 is an external view when a part of the cleaning device 40 is viewed from above (however, the film-like member 71 is not shown). The support plate 42b has a contact portion 421 that contacts the eccentric cam 52a and a connecting portion 422 for connecting to the shaft blade 42a, and has an L-shape when viewed from above. When the eccentric cam 52a rotates, the eccentric cam 52a presses the contact portion 421 at a constant cycle, and the pressing force is transmitted to the cleaning blade 41 through the shaft blade 42a, so that the cleaning blade 41 slides.

  Returning to FIG. 3 and FIG. The film-like member 71 prevents the toner from entering the driving device 50, and is an insulating and heat-resistant film-like member having a predetermined elasticity. The film-like member 71 is disposed so as to cover the driving device 50 between the cleaning device 40 and the driving device 50.

  More specifically, the housing 72 that houses the cleaning device 40 has an opening 722 at a position facing the cleaning device 40. In order to prevent the toner from entering the housing 72 through the opening 722, the end 71a of the film-like member 71 is attached to the vertical surface 721 near the cleaning device 40 on the upper surface side of the housing 72 with an adhesive or the like. The opening 722 is covered with the film-like member 71. The end 71b located on the opposite side to the end 71a is not fixed to any part and is in a variable state.

  The length (short side) from the end 71 a to the end 71 b of the film-like member 71 is set to a length that can sufficiently cover the opening 722. Further, the film-like member 71 has a rectangular shape having a long side in the X direction. However, since the eccentric cam 52a and the contact portion 421 need to contact each other, the entire opening 722 is covered with the film-like member 71. Inconvenience occurs.

  Therefore, as shown in FIG. 6, the film-like member 71 is pasted so as not to cover the position where the eccentric cam 52a and the contact portion 421 are in contact with each other, but to cover the other region. FIG. 6 is a perspective view of the housing 72 as viewed from the upper surface lid 33 side. The region 73 is a region where the opening 722 is not covered with the film-like member 71 so that the eccentric cam 52a and the contact portion 421 come into contact with each other. The width of the region 73 in the X direction is desirably minimized in order to prevent toner from entering the housing 72.

  Next, operations of the eccentric cam 52a and the holding member 42BK will be described with reference to FIGS. 7 and 8 are front sectional views showing a part of the cleaning device 40 and the driving device 50. FIG. First, as shown in FIG. 7A, when the solenoid 62 is energized and the projection 611 is unlocked by the claw 621, the clutch 61 starts to rotate in the direction of arrow P, and similarly the eccentric cam. 52a also rotates in the direction of arrow P. When the eccentric cam 52a rotates, as shown in FIG. 7B, the eccentric cam 52a contacts the support plate 42b and presses the shaft blade 42a. As a result, the cleaning blade 41BK slides in the arrow S direction, and the dustproof glass 304 is cleaned.

  As described above, it is preferable that the width in the X direction of the region 73 that is not covered with the film-like member 71 and is in the open state is minimal. In this case, the eccentric cam 52a and the film-like member 71 are very close to each other. Will be placed. For this reason, depending on how the film-like member 71 is attached or how the cleaning device 40 and the drive device 50 are assembled, the support plate 42b hits the film-like member 71 when the cleaning device 40 reciprocates, and the film-like member 71 The shape and position of the member 71 sometimes changed.

  When the shape or position of the film-like member 71 changes, the projection 611 may interfere with the film-like member 71 as shown in FIG. The film-like member 71 indicated by a solid line is when the shape and position are not changed, and the film-like member 71 indicated by a dotted line is when the shape and position are changed. When the film-like member 71 is in the position indicated by the dotted line, there is a problem that the projection 611 is caught by the film-like member 71 when the clutch 61 rotates, and the clutch 61 stops at a position other than the reference position.

  The fact that the clutch 61 stops at a position other than the reference position indicates that the protrusion 611 is not locked to the claw 621 and the clutch 61 is not fixed. Accordingly, when the laser beam for forming the electrostatic latent image is emitted from the LSU 6 (during exposure), the clutch 61 is rotated by receiving some force from the outside, and the cleaning blade 41 slides to emit the laser beam. There is a possibility of blocking. When such a phenomenon actually occurs, the formed image becomes a blank image.

  Therefore, after the cleaning operation of the dust-proof glass 304 by the cleaning blade 41 (hereinafter simply referred to as “cleaning operation”) is completed, the DC motor M rotates the clutch 61 in the reverse direction by a predetermined angle under the control of the control unit 90 and then rotates it forward. By engaging the projection 611 and the claw 621, the clutch 61 and the eccentric cam 52a are always stopped at the reference position at times other than cleaning work. This method will be described in detail with reference to FIGS.

  In FIG. 9, reference numeral 611a denotes a protrusion when the clutch 61 is stopped at the reference position, and reference numerals 611b and 611c denote protrusions when the clutch 61 is stopped at a position other than the reference position. 611 c is at a position facing the film-like member 71. The projecting portion 611 and the film-like member 71 are close to the position facing the film-like member 71, and the projecting portion 611 and the film-like member 71 can be in contact with each other depending on the position and shape of the film-like member 71. It is a highly probable position. Hereinafter, the position range of the projecting portion 611 that is likely to come into contact with each other because the film-like member 71 and the projecting portion 611 approach each other is referred to as a “range facing the film-like member 71”.

  A supplementary description will be given of the “range facing the film-like member 71”. The protrusion 611b is closest to the reference position (position of the protrusion 611a) in the range facing the film-like member 71, and the protrusion 611c is most from the reference position in the range facing the film-like member 71. It can be said that it is a distant position. That is, as shown in FIG. 9A, the angle formed by the line segment connecting the projection 611a when the clutch 61 is at the reference position and the line segment connecting the center axis and the projection 611b is the same. As shown in FIG. 9B, when the angle formed by the line segment connecting the central axis and the protrusion 611a and the line segment connecting the central axis and the protrusion 611c is an angle β as shown in FIG. The range facing the angle is the range from the angle α to the angle β. If the projection 611 is in this range, the possibility of contact depending on the position and shape of the film-like member 71 increases.

  In order to avoid this contact, the clutch 61 is reversely rotated by a predetermined angle, but the protrusion 611c located farthest from the reference position in the range facing the film-like member 71 is more than the protrusion 611a being the reference position. Rotate it back so that it comes to the front side during forward rotation. Thereafter, by rotating the clutch 61 forward, it can be engaged with the claw 621 at the position of the protrusion 611a. That is, the reverse rotation angle θ may be set in a range of β <θ <180 °.

  The reverse rotation operation of the clutch 61 will be described. FIG. 10 is a front sectional view of the cleaning device 40 and the driving device 50, and FIG. 11 is a flowchart showing a flow of control of the driving device 50 by the control unit 90.

  First, the control unit 90 turns on the solenoid 62 (ON state) (step S11). As a result, the claw 621 is switched from the locking position to the non-locking position, and the clutch 61 is released from the restriction by the claw 621. And the control part 90 connects the clutch 61 (step S12). Thereby, the driving force of the DC motor M is transmitted to the rotating shaft 51 and the eccentric cam 52, and the dustproof glass 304 is cleaned by the cleaning device 40 (step S13).

  After the cleaning device 40 repeats the reciprocating motion a predetermined number of times (after a predetermined time has elapsed after the clutch 61 is connected), the control unit 90 rotates the clutch 61 in the reverse angle θ (step S14). That is, as shown in FIG. 10A, the clutch 61 rotates reversely in the direction of the arrow Q, and, for example, the protrusion moves from 611b to 611d. At the same time, the clutch 52a moves from the position of the solid line to the position of the two-dot chain line.

  And the control part 90 makes the solenoid 62 a non-energized state (OFF state) (step S15). Thereby, the claw 621 is switched to the locking position. When the controller 90 rotates the clutch 61 forward (step S16), the protrusion 611 and the claw 621 are engaged, and the clutch 61 and the eccentric cam 52a stop at the reference position. That is, as shown in FIG. 10B, the clutch 61 rotates forward in the direction of the arrow P, and the protrusion moves from the position 611d to the position 611a that is the home position. At the same time, the clutch 52a moves from the two-dot chain line position to the solid line position.

  Thereafter, the control unit 90 disconnects the clutch 61. As a result, the rotation shaft 51 and the eccentric cam 52a lose their drive sources and stop rotating, and the cleaning operation by the cleaning device 40 ends.

  As described above, after cleaning by the cleaning device 40, the clutch 61 is rotated reversely by the angle θ, and then the solenoid 61 is deenergized and the clutch 61 is rotated forward so that the clutch 61 and the eccentric cam 52a are used as a reference. It can be stopped reliably at the position. Therefore, when the projection 611 is caught by the film-like member 71, the clutch 61 and the eccentric cam 52a are stopped at a position other than the reference position, and then they are rotated by an unexpected external force, so that the cleaning operation is performed during the exposure. It is possible to prevent a situation where the laser beam for forming the electrostatic latent image is blocked.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, if the rotational speed when the DC motor M rotates the clutch 61 forward is N, the rotational speed is less than N (for example, rotational speed N / 2) during reverse rotation. By doing so, it is possible to prevent the clutch 61 from rotating too much due to the inertial rotation of the DC motor M, and to improve the stop position accuracy during reverse rotation.

  explain in detail. 12 and 13 are diagrams showing changes in the signal waveform of the motor remote signal and the rotational speed of the DC motor M during reverse rotation, and FIG. 12 shows a diagram when the rotational speed is the rotational speed N during forward rotation. Reference numeral 13 denotes a case where the rotational speed is N / 2. The motor remote signal is a signal output from the control unit 90 to the DC motor M. When the motor remote signal is ON (H level), the DC motor M rotates, and when the motor remote signal is OFF (L level), it stops. For the rotation direction (forward / reverse) of the DC motor M, a control signal for instructing the rotation direction is output separately.

  As shown in FIG. 12, when the DC motor M is reversely rotated at the rotational speed N and stopped, the DC motor M rotates inertially after the stop, so that the DC motor M is completely turned off after the motor remote signal is turned OFF. It takes time t12 to stop. The stop time t12 due to this inertial rotation greatly depends on variations in the characteristics of the DC motor M. The long inertia rotation time means that the stop position is not fixed, and if it rotates too much, it takes time until the subsequent forward rotation operation and the operation of stopping the clutch 61 at the reference position are completed. It will take.

  Therefore, as shown in FIG. 13, the rotational speed at the time of reverse rotation is set to be less than the rotational speed at the time of forward rotation (for example, N / 2). By doing so, the time t22 from when the motor remote signal is turned OFF until the DC motor M is completely stopped is shortened. That is, the inertial rotation time is shortened and the time during which the motor remote signal is ON is lengthened, so that the accuracy of the stop position of the DC motor M can be improved. Therefore, the stop position of the clutch 61 can be easily controlled, and the operation of stopping the clutch 61 at the reference position can be performed smoothly.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 4 Photosensitive drum (Image carrier)
6 LSU (exposure means)
31 LSU body 33 Upper lid (housing)
40 Cleaning device (cleaning means)
41 Cleaning blade (dust removal means)
42 Holding member (transmission means)
50 Driving device (driving means)
52 Eccentric Cam 61 Clutch 611 Protrusion 62 Solenoid (Stopping Means)
621 Claw 71 Film-like member 90 Control unit (drive control means)
303 Outlet 304 Dustproof glass M DC motor

Claims (3)

An image carrier for carrying an electrostatic latent image;
Exposure means for irradiating light based on image data toward the image carrier;
A casing having the exposure means disposed therein and having a transmission window that transmits light emitted from the exposure means;
An eccentric cam that is rotationally driven by a driving force transmitted from a driving source; a clutch that has a protrusion on a part of an outer periphery thereof; and that switches whether or not the driving force is transmitted from the driving source to the eccentric cam; A driving means having a claw to engage, and a stopping means for stopping the clutch at a reference stop position by engaging the claw with the protrusion.
Dust removing means for removing dust adhering to the transmissive window by sliding on the surface of the transmissive window, and transmitting the driving force of the driving means to the dust removing means to slide the dust removing means. A cleaning means having a transmission means;
A film-like member interposed between the driving means and the cleaning means;
Drive control means for controlling the operation of the clutch, and for switching the claw to either the engagement position where the protrusion is engaged or the non-engagement position where the protrusion is not engaged with the stop means;
And after the cleaning of the transmission window by the cleaning means, the drive control means switches the claw to the disengaged position with respect to the stop means and reverses the clutch by a predetermined angle. An image forming apparatus that rotates, and then stops the clutch at the reference stop position by causing the stop means to switch the claw to the engagement position to rotate the clutch forward.   The predetermined angle is an angle that is larger than an angle formed by the engagement position and a position farthest from the engagement position in a range where the projection portion is located at a position facing the film-like member. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 1, wherein the drive control unit rotates the clutch at a speed slower than that at the time of forward rotation when the clutch is reversely rotated at the predetermined angle.

Images