JP2017227852A - Optical scanner and image forming apparatus including the optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner comprising a cleaning member that rubs a transparent cover part 46 covering a light emission port of the optical scanner, holding members 52 holding the cleaning member, and a driving mechanism 53 driving the holding members 52, and accurately perform detection of the movement ends for the holding members 52 while preventing a motor 57 being part of the driving mechanism 53 from being locked.SOLUTION: Photointerrupters 60 are provided respectively at the movement ends of reciprocation paths A for holding members 52. The holding members 52 are each provided with a detection target part 52b that shields, from light, a space between a light receiving part 60a and a light emitting part 60b of the photointerrupter 60 at each of the movement ends of the reciprocation paths A.SELECTED DRAWING: Figure 4

Description

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

  An image forming apparatus that employs an electrophotographic system such as a copying machine or a printer includes an optical scanning device that emits light for forming an electrostatic latent image on a photosensitive member, and an electrostatic latent image formed on the photosensitive member as a toner. And a developing device for developing as an image.

  The optical scanning device has a housing that houses a polygon mirror, an imaging lens, and the like. The housing is formed with an emission port through which light is emitted. The emission port includes an opening extending in a predetermined direction. The exit is closed by a transparent cover such as dust-proof glass.

  By the way, when dirt or dust due to toner or the like adheres to the surface of the dust-proof glass, there is a problem in that the optical characteristics of the optical scanning device deteriorate and an image defect occurs. On the other hand, Patent Document 1 discloses a cleaning mechanism that periodically cleans the surface of dust-proof glass.

  The cleaning mechanism of Patent Literature 1 includes a screw shaft that extends in the same direction as the extending direction of the dust-proof glass, and a holding member that engages with the screw shaft and holds the cleaning member. The screw shaft is connected to the motor through a gear train so as to be able to transmit power.

  The holding member reciprocates along the screw shaft as the screw shaft is rotated forward and backward by a motor. Thereby, the cleaning member reciprocates while contacting the surface of the transparent cover part, and the surface of the transparent cover part is cleaned by the cleaning member.

  In this type of cleaning mechanism, a timer control method or an overcurrent detection method is employed as a detection method for detecting that the holding member has reached the moving end. In the former case, the controller measures the elapsed time from the start of driving the motor to the present time, and determines that the holding member has reached the moving end when the elapsed time reaches a preset set time. In the latter case, it is determined that the holding member has reached the moving end when an overcurrent flows through the motor due to the holding member reaching the moving end.

JP 2012-185507 A

  However, when the timer control method is adopted, if the moving speed of the holding member fluctuates due to variations in the output of the motor, etc., the motor stops even before the holding member reaches the moving end, or even after the holding member reaches the moving end. There is a problem that the drive current is supplied and the motor is locked. Further, when the overcurrent detection method is adopted, there is a problem that the motor is similarly locked due to overcurrent. When the output of the motor is high, there is a possibility that the gear locks out by locking the motor.

  The present invention has been made in view of such a point, and an object of the present invention is to reliably detect that the holding member has reached each moving end while preventing the motor from being locked by overcurrent. Is to make it.

  An optical scanning device according to the present invention includes a housing having a light emission port extending in a predetermined direction, a transparent cover portion that closes the light emission port, and a cleaning member that slidably contacts the surface of the transparent cover portion to clean the surface. A holding member that holds the cleaning member, a drive mechanism that reciprocates the holding member along the transparent cover portion in the predetermined direction, and a motor that is a part of the drive mechanism and generates a driving force. A moving end detector that detects that the holding member has reached each moving end of the reciprocating path, and a motor controller that stops the motor when the moving end of the holding member is detected by the moving end detector. It has.

  The holding member further includes a pair of photointerrupters provided for each moving end of the reciprocating path of the holding member, and the holding member has an intermediate position in the moving direction of the reciprocating path. When the holding member reaches each moving end of the reciprocating path, the light emitting unit and the light receiving unit of each photo interrupter are positioned outside the light emitting unit and the light receiving unit of each photo interrupter. A detection unit located between the photointerrupters is provided, and the moving end detection unit is configured to reciprocate the holding member when the light-receiving unit and the light-receiving unit of each photo interrupter are shielded from light by the detection unit. It is configured to detect that each moving end of the route has been reached.

  According to the present invention, it is possible to reliably detect that the holding member has reached each moving end while preventing the motor from locking due to overcurrent.

FIG. 1 is a schematic configuration diagram of an image forming apparatus including an optical scanning device according to the embodiment. FIG. 2 is a perspective view showing the optical scanning device. FIG. 3 is a schematic view showing the structure inside the housing body of the optical scanning device. FIG. 4 is a plan view showing a cleaning mechanism of the optical scanning device. FIG. 5 is a perspective view showing a state in which the holding member that holds the cleaning member is at the moving end. FIG. 5 is a plan view showing details of the VI part of FIG. 7 is a view taken in the direction of arrow VII in FIG. FIG. 8 is a flowchart showing the contents of motor drive control in the control unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

<Embodiment>
FIG. 1 is a schematic configuration diagram of an image forming apparatus 1 according to an embodiment of the present invention. In the following description, the front side and the rear side mean the front side and the rear side (the front side and the rear side in the direction perpendicular to the paper surface in FIG. 1), and the left side and the right side refer to the image forming apparatus 1 from the front side. It means the left side and the right side when viewed.

  The image forming apparatus 1 is a tandem color printer, and includes an image forming unit 3 in a box-shaped casing 2. The image forming unit 3 transfers and forms an image on the recording paper P based on image data transmitted from an external device such as a computer connected to a network. An optical scanning device 4 that emits laser light is disposed below the image forming unit 3, and a transfer belt 5 is disposed above the image forming unit 3. A paper storage unit 6 that stores the recording paper P is disposed below the optical scanning device 4, and a manual paper feed unit 7 is disposed on the left side of the paper storage unit 6. On the right side and the upper side of the transfer belt 5, a fixing unit 8 that performs a fixing process on an image transferred and formed on the recording paper P is disposed. Reference numeral 9 denotes a paper discharge unit that is disposed on the casing 2 and discharges the recording paper P that has been subjected to fixing processing by the fixing unit 8.

  The image forming unit 3 includes four image forming units 10 arranged in a line along the transfer belt 5. These image forming units 10 have a photosensitive drum 11. A charger 12 is disposed immediately below each photoconductive drum 11, a developing device 13 is disposed on the left side of each photoconductive drum 11, and a primary transfer roller 14 is disposed directly above each photoconductive drum 11. A cleaning unit 15 for cleaning the peripheral surface of the photoconductive drum 11 is disposed on the right side of each photoconductive drum 11.

  Each photosensitive drum 11 is charged with a constant peripheral surface by a charger 12, and the laser corresponding to each color based on image data input from the computer or the like is applied to the peripheral surface of the photosensitive drum 11 after charging. Light is irradiated from the optical scanning device 4, and an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 11. Developer is supplied to the electrostatic latent image from the developing device 13, and a yellow, magenta, cyan, or black toner image is formed on the peripheral surface of each photosensitive drum 11. These toner images are respectively transferred to the transfer belt 5 by a transfer bias applied to the primary transfer roller 14.

  Reference numeral 16 denotes a secondary transfer roller disposed in contact with the transfer belt 5 below the fixing unit 8, and is recorded on the sheet conveyance path 17 from the sheet storage unit 6 or the manual sheet feeding unit 7. The paper P is sandwiched between the secondary transfer roller 16 and the transfer belt 5, and the toner image on the transfer belt 5 is transferred to the recording paper P by the transfer bias applied to the secondary transfer roller 16.

  The fixing unit 8 includes a heating roller 18 and a pressure roller 19. The toner image transferred onto the recording paper P is heated by holding the recording paper P between the heating roller 18 and the pressure roller 19 while being pressed. Is fixed to the recording paper P. The recording paper P after the fixing process is discharged to the paper discharge unit 9. Reference numeral 20 denotes a reversing conveyance path for reversing the recording paper P discharged from the fixing unit 8 during double-sided printing.

-Details of optical scanning device-
FIG. 2 is an external perspective view of the optical scanning device 4. The optical scanning device 4 includes a sealed box-shaped housing 40. The housing 40 includes a bottomed box-shaped housing main body 41 that opens on the ceiling side, and a lid member 42 that closes the ceiling side of the housing main body 41.

  FIG. 3 is a cross-sectional view showing a state where the lid member 42 is removed from the housing 40 of the optical scanning device 4. A polygon mirror 43 and a polygon motor 44 that rotationally drives the polygon mirror 43 are disposed at the center of the bottom wall portion of the housing body 41. The polygon mirror 43 deflects and scans a laser beam for writing an electrostatic latent image corresponding to each color of magenta (M), cyan (C), yellow (Y), and black (K) emitted from a light source. A total of four scanning optical systems S are arranged on the bottom wall of the housing body 41, two on each side of the polygon mirror 43. The four scanning optical systems S guide laser light corresponding to each color of magenta (M), cyan (C), yellow (Y), and black (K) to the surface of each photosensitive drum 11. These scanning optical systems S are composed of, for example, an fθ lens, a reflection mirror, and the like.

  The lid member 42 is formed with two sets (four in total) of one to one set of emission ports 45 through which the laser beams emitted from the respective scanning optical systems S pass (see FIG. 2). Each emission port 45 includes a rectangular opening extending in the front-rear direction (that is, the main scanning direction). The respective emission ports 45 are formed in parallel in the left-right direction (direction perpendicular to the main scanning direction) with a space therebetween. Each exit 45 is covered with a dustproof glass 46 as a transparent cover. Each dust-proof glass 46 covering each emission port 45 is formed in a rectangular plate shape that is long in the front-rear direction. The surface of each dustproof glass 46 is automatically cleaned by an automatic cleaning mechanism 50.

  The automatic cleaning mechanism 50 includes a pair of left and right holding members 52 and a drive mechanism 53 that reciprocates the pair of holding members 52 in the front-rear direction. Each holding member 52 is composed of a plate-like member that is long in the left-right direction, and the cleaning member 51 (only the cleaning member 51 held by the right holding member 52 is shown in FIG. ) Is held. Each cleaning member 51 is formed of an elastic blade member (for example, a silicon pad). Each cleaning member 51 is engaged and held in an engagement hole 52 a (see FIG. 5) formed in the holding member 52. Each cleaning member 51 is provided at a position corresponding to each dustproof glass 46. That is, each cleaning member 51 is provided at a position overlapping each dustproof glass 46 in plan view. Each cleaning member 51 is sandwiched between the holding member 52 and the dust-proof glass 46 and compressed with a light load in the thickness direction. Thereby, each cleaning member 51 is pressed against the dust-proof glass 46 with a predetermined pressing force. In this state, the holding member 52 is reciprocated by the drive mechanism 53 so that the surface of each dustproof glass 46 is cleaned.

  As shown in FIG. 4, the drive mechanism 53 includes a wire 54, a drum 55, four pulleys 56, and a motor 57. The wire 54 is disposed on the upper surface of the housing 40 so as to form a rectangular ring shape. A holding member 52 is fixed to two sides of the wire 54 that extend in the front-rear direction. The four pulleys 56 are disposed at the four corners of the rectangular annular wire 54 and guide the wire 54 so as to be movable in the circumferential direction. The drum 55 is attached to a right side portion of the rear end portion of the housing 40. The drum 55 is fixed integrally with a drive shaft of a motor 57 provided in the housing 40. Both ends of the wire 54 are wound around a drum 55. At one end and the other end of the wire 54, the winding direction around the drum 55 is reversed. Thus, for example, when the drum 55 rotates forward, one end side of the wire 54 is pulled out from the drum 55 and the other end side is wound around the drum 55, and when the drum 55 rotates backward, one end side of the wire 54 is wound around the drum 55. The other end side is pulled out from the drum 55.

  When the automatic cleaning mechanism 50 is operated, the motor 57 is rotationally driven in both forward and reverse directions. Thereby, each holding member 52 moves along a predetermined reciprocating path A extending in the front-rear direction. In the initial state before the cleaning by the automatic cleaning mechanism 50, the left holding member 52 is positioned at the front moving end of the reciprocating path A, and the right holding member 52 is positioned at the rear moving end of the reciprocating path A. doing. When the motor 57 rotates forward in this state, the drum 55 rotates forward and the wire 54 rotates clockwise in FIG. Thereby, each holding member 52 moves in the direction of the black arrow in the figure. When the left holding member 52 reaches the rear moving end of the reciprocating path A, the right holding member 52 reaches the front moving end. Then, when the motor 57 rotates in the reverse direction, the drum 55 rotates in the reverse direction and the wire 54 rotates in the counterclockwise direction. As a result, each holding member 52 moves in the direction of the white arrow in the figure and returns to the initial state. Thus, when the reciprocating movement of each holding member 52 is completed, the cleaning of each dustproof glass 46 by the cleaning member 51 is completed.

  A pair of front and rear photointerrupters 60 for detecting that each holding member 52 has reached each moving end of the reciprocating path A are provided on the upper surface of the housing 40. The holding member 52 has a detected portion 52 b that can be detected by each photo interrupter 60. Details of the detected portion 52b will be described later.

  A pair of photo interrupters 60 is provided for each moving end of the reciprocating path A of the left holding member 52. The photointerrupter 60 is not provided in the reciprocating path A of the right holding member 52. Since the left holding member 52 and the right holding member 52 move symmetrically alternately in the front-rear direction, the moving end of the left holding member 52 is detected without directly detecting the moving end of the right holding member 52. This is because the moving end of the right holding member 52 can also be indirectly detected.

  As shown in FIGS. 6 and 7, each photo interrupter 60 has a light emitting unit 60 a and a light receiving unit 60 b that are arranged to face each other. Each photo interrupter 60 is connected to the controller 100 via a signal line. Each photo interrupter 60 outputs a light transmission signal when the light emitting unit 60a and the light receiving unit 60b are in a light transmitting state, and outputs a light shielding signal when in a light blocking state.

  The detected portion 52b has a horizontal plate portion 52c extending horizontally from the left end portion of the holding member 52 to the left side, and a vertical plate portion 52d extending downward from the tip end portion of the horizontal plate portion 52c. When the left holding member 52 is located in the middle part of the reciprocating movement path A, the vertical plate part 52d is located outside the light emitting part 60a and the light receiving part 60b of the photo interrupter 60. On the other hand, the vertical plate portion 52d is positioned between the light emitting portion 60a and the light receiving portion 60b of the front photointerrupter 60 when the left holding member 52 reaches the front end of the reciprocating path A, and When it reaches the side end, it is configured to be positioned between the light emitting portion 60a and the light receiving portion 60b of the rear photo interrupter 60. The vertical plate portion 52d shields the light emitting portion 60a and the light receiving portion 60b of each photo interrupter 60 when the holding member 52 is positioned at each moving end of the reciprocating movement path A.

  The controller 100 determines (detects) that the left and right holding members 52 have reached the moving end of the reciprocating path A when receiving a light shielding signal from the photo interrupter 60, while holding the left and right when receiving a translucent signal. It is configured to determine (detect) that the member 52 is located in the middle part of the reciprocating path A. Thus, the controller 100 detects that the holding member 52 has reached each moving end of the reciprocating movement path A when the light emitting portion 60a and the light receiving portion 60b of each photo interrupter 60 are shielded from light. Functions as a detector.

  Next, drive control of the motor 57 by the controller 100 will be described with reference to the flowchart of FIG.

  In the first step S1, the motor 57 is driven in the forward rotation direction by starting the current supply to the motor 57.

  In step S2, it is determined whether or not a predetermined time T has elapsed from the start of driving of the motor 57 in the forward rotation direction. If this determination is NO, the process of step S2 is executed again. If there is, the process proceeds to step S3. Here, the predetermined time is shorter than the minimum time required for the vertical plate portion 52d to completely come out from the inside between the light emitting portion 60a and the light receiving portion 60b of the photo interrupter 60 as the holding member 52 moves. It is a little long time. In this embodiment, this predetermined time is set to 0.02 seconds, for example.

  In step S3, it is determined whether or not a light-shielding signal is received from the photo interrupter 60. If this determination is NO, the process of this step S3 is executed again. Assuming that the member 52 has reached the moving end of the reciprocating movement path A, the process proceeds to step S4.

  In step S4, the current supply to the motor 57 is stopped to stop the motor 57.

  In step S5, it is determined whether or not a preset set time (for example, 0.02 seconds in this embodiment) has elapsed. If this determination is NO, the process of step S5 is executed again, and YES. If so, the process proceeds to step S6.

  In step S6, the current supply to the motor 57 is resumed to drive the motor 57 in the reverse direction.

  In step S7, it is determined whether or not the predetermined time T has elapsed from the start of driving of the motor 57 in the reverse rotation direction. If this determination is NO, the process of this step S7 is executed again, and YES. If there is, the process proceeds to step S8.

  In step S8, it is determined whether or not a light-shielding signal from the photo interrupter 60 has been received. If this determination is NO, the process of step S8 is executed again. If YES, the process proceeds to step S9. move on.

  In step S9, the motor 57 is stopped by stopping the current supply to the motor 57, and then the drive control of the motor 57 is terminated.

  In the optical scanning device 4 configured as described above, the controller 100 includes a holding member when the light emitting unit 60a and the light receiving unit 60b of each photo interrupter 60 are shielded from light by the vertical plate unit 52d of the detected unit 52b. It is configured to stop the motor 57 by detecting that 52 has reached each moving end of the reciprocating path A.

  According to this configuration, the detection accuracy of the moving end of the holding member 52 can be improved as compared with the case where it is detected that the holding member 52 has reached the moving end by a timer control method or an overcurrent detection method. Therefore, it is possible to prevent an overcurrent from flowing through the motor 57 by delaying the detection of the moving end of the holding member 52. As a result, it is possible to prevent the motor 57 from being locked and causing tooth skipping in the drive gear system. Further, since the moving end detection of the holding member 52 is too early, it is possible to prevent the holding member 52 from stopping before reaching the moving end.

  Further, in the above embodiment, a wire drive system is adopted as the drive mechanism 53 of the left and right holding members 52, and the pair of photo interrupters 60 are only for the moving ends of the reciprocating path A of the left holding member 52. It is provided for each moving end of the reciprocating path A of the holding member 52 on the right side.

  According to this configuration, the number of photointerrupters 60 can be reduced as compared with the case where the photointerrupters 60 are provided in the reciprocating path of both the left and right holding members 52, so that the product cost can be reduced. Further, since it is not necessary to secure a space for placing the photo interrupter 60 for the right holding member 52, the horizontal dimension of the optical scanning device 4 is reduced by that much, thereby reducing the size of the entire device. Can do.

<< Other embodiments >>
In the above embodiment, the wire drive system is adopted as the drive mechanism 53 of the holding member 52, but the present invention is not limited to this, and a screw drive system in which the holding member 52 is screwed onto the screw shaft is adopted. It may be.

  As described above, the present invention is useful for an optical scanning device and an image forming apparatus including the optical scanning device.

A Reciprocating path 1 Image forming device 4 Optical scanning device 40 Housing 45 Outlet port 46 Dust-proof glass (transparent cover part)
DESCRIPTION OF SYMBOLS 50 Automatic cleaning mechanism 51 Cleaning member 52 Holding member 52b Detected part 53 Drive mechanism 54 Wire 55 Drum 56 Pulley 57 Motor 60 Photo interrupter 60a Light emitting part 60b Light receiving part 100 Controller (moving end detection part, motor control part)

Claims (3)

A housing having a light exit opening extending in a predetermined direction, a transparent cover portion that closes the exit opening, a cleaning member that slides on the surface of the transparent cover portion to clean the surface, and a holder that holds the cleaning member A member, a drive mechanism that reciprocates the holding member in the predetermined direction along the transparent cover portion, a motor that is a part of the drive mechanism and generates a driving force, and the holding member that moves along the reciprocating path. The optical scanning device includes a moving end detector that detects that each moving end has been reached, and a motor controller that stops the motor when the moving end of the holding member is detected by the moving end detector. And
A pair of photo interrupters provided for each of the moving ends of the reciprocating path of the holding member;
The holding member is positioned outside the light-emitting portion and the light-receiving portion of each photo interrupter when the holding member is located at an intermediate portion in the moving direction of the reciprocating path, and the holding member is positioned on the reciprocating path. A detected portion located between the light emitting portion and the light receiving portion of each photo interrupter when each moving end is reached,
The moving end detection unit detects that the holding member has reached each moving end of the reciprocating path when the detected portion shields light between the light emitting unit and the light receiving unit of each photo interrupter. An optical scanning device configured as described above. The optical scanning device according to claim 1,
At least two exits are provided, and the at least two exits are arranged side by side in a direction orthogonal to the predetermined direction,
The holding member is provided with respect to the transparent cover portion covering the emission ports,
The drive mechanism has an annular wire to which the two holding members are fixed, a pulley around which the wire is wound, and a motor that drives the pulley, and the pulley is rotated by the motor. By driving the wire in the circumferential direction of the pulley, each holding member is configured to reciprocate in the predetermined direction,
The photo interrupter is provided only for each moving end of the reciprocating path of one of the two holding members, and provided for each moving end of the reciprocating path of the other holding member. Optical scanning device that is not. An image forming apparatus comprising the optical scanning device according to claim 1.

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