JP2012098648A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of avoiding resonance caused by an oscillation frequency of an optical deflector getting closer to a characteristic frequency of a housing.SOLUTION: An image forming apparatus comprises: an exposure device including an optical deflector having a rotating shaft for rotating a polygon mirror which exposes and scans light to a photoreceptor and a rotating shaft bearing part for supporting the rotating shaft, and a housing which accommodates the optical deflector and has an exposure hole for exposing the rotating shaft bearing part of the optical deflector; a housing support member for supporting the housing; and a heat radiation member which is arranged between the housing and the housing support member and supported between the rotating shaft bearing part and the housing support member so as to be in contact with the housing support member. The housing support member and the heat radiation member are configured to be changeable in the support force for supporting the rotating shaft bearing part by rotating the heat radiation member.

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus having an exposure device that exposes a photosensitive member with a laser beam is known (see, for example, Patent Document 1). The exposure apparatus has a rotary polygon mirror and a motor that drives the rotary polygon mirror, and the motor rotates the rotary polygon mirror at high speed to deflect and scan the laser beam to expose the photosensitive member.

JP 2010-78836 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of avoiding resonance caused by the vibration frequency of an optical deflector approaching the natural frequency of a housing of an exposure apparatus.

  In order to achieve the above object, an image forming apparatus according to claim 1 includes an optical deflector having a rotating shaft that rotates a polygon mirror that exposes and scans a photosensitive member with light, and a rotating shaft bearing that supports the rotating shaft, and An exposure apparatus having a housing that accommodates the optical deflector and has an exposure hole that exposes the rotary shaft bearing portion of the optical deflector, a housing support member that supports the housing, and the housing A heat radiating member disposed between the rotary shaft bearing portion and the housing support member so as to be in contact with the housing support member. The body support member and the heat radiating member are configured to be capable of changing a support force for supporting the rotary shaft bearing portion by rotating the heat radiating member.

  The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1, wherein the heat radiating member is rotatable with respect to the plurality of contact portions that can contact the housing support member and the rotary shaft bearing portion. A support portion that supports the housing support member, and when the one contact portion comes into contact with the housing support member, the housing support member has a relief portion that prevents the other contact portion from coming into contact with the housing support member. The width or length of the one contact portion is different from the corresponding width or length of the other contact portion.

  The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1, wherein the heat dissipating member is formed by superimposing a plurality of members, and each member is a contact portion that can contact the housing support member. And a support portion that rotatably supports the rotary shaft bearing portion. When the one member contacts the case support member, the other member supports the case. A relief portion that does not contact the member, and at least one of the width, thickness, length, and Young's modulus of the contact portion of the one member corresponds to the corresponding width, thickness, length of the contact portion of the other member It differs from at least one of thickness and Young's modulus.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the second aspect, at least one of a protruding portion and a groove portion is formed on the housing support member.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the third aspect, at least one of a projecting portion and a groove portion is formed on the housing support member.

  The image forming apparatus according to claim 6 is the image forming apparatus according to claim 1, wherein the heat radiating member is rotatably supported with respect to the contact portion that can come into contact with the housing support member and the rotary shaft bearing portion. A support portion, and at least one of a protruding portion and a groove portion is formed on the housing support member.

  According to the first aspect of the present invention, it is possible to avoid the resonance that occurs when the vibration frequency of the optical deflector is close to the natural frequency of the casing of the exposure apparatus.

  According to the second aspect of the invention, the supporting force for supporting the rotary shaft bearing portion can be changed by changing the spring coefficient of the heat radiating member.

  According to the invention of claim 3, the supporting force for supporting the rotary shaft bearing portion can be changed by changing the spring coefficient of the heat radiating member.

  According to the invention of claim 4, the support force for supporting the rotary shaft bearing portion can be changed by changing the deflection amount of the heat radiating member.

  According to the invention of claim 5, the supporting force for supporting the rotary shaft bearing portion can be changed by changing the deflection amount of the heat radiating member.

  According to the invention of claim 6, the supporting force for supporting the rotary shaft bearing portion can be changed by changing the deflection amount of the heat radiating member.

1 is a schematic configuration diagram of an image forming apparatus 1 according to the present embodiment. FIG. 2 is a schematic configuration diagram of an image forming unit 30 in FIG. 1. 2 is a schematic configuration diagram of an intake section 60 and an exhaust section 100. FIG. FIG. 6 is an explanatory diagram showing the flow of air from the front cover to the intake section 60. It is a schematic block diagram of the exposure unit 40 and the frame 41 of FIG. It is a figure which shows the AA cross section of FIG. FIG. 6 is a diagram showing a relationship between a vibration frequency of a sleeve 204 generated by two rotation modes of a motor 251 and a frequency response function of a housing 150. (A) is a figure which shows an example of a structure of the heat radiating member 219 at the time of seeing the heat radiating member 219 from upper direction. (B) is a figure which shows the B1-B1 cross section of FIG. 8 (A). (C) is a figure which shows the C1-C1 cross section of FIG. 8 (A). FIG. 9D is a diagram illustrating a state in which the heat dissipating member 219 of FIG. 8A is rotated 90 degrees clockwise or counterclockwise. (E) is a figure which shows the 1st modification of the heat radiating member 219. FIG. (F) is a diagram showing a second modification of the heat dissipation member 219. (A) is a figure which shows the 3rd modification of the heat radiating member 219. FIG. (B) is a figure which shows the B2-B2 cross section of FIG. 9 (A). (C) is a figure which shows the C2-C2 cross section of FIG. 9 (A). (D) is a figure which shows the modification of the C2-C2 cross section of FIG. 9 (A). (E) is a figure which shows the 4th modification of the heat radiating member 219. FIG. (A) is a figure which shows an example of a structure of the flame | frame 41 at the time of seeing the thermal radiation member 219 and the flame | frame 41 from upper direction. FIG. 10B is a diagram illustrating a DD cross section of FIG. 10A when the leg portion 232 of the heat radiating member 219 is disposed on the protruding portion of the frame 41. FIG. 10C is a diagram showing a cross section taken along the line E-E in FIG. 10A when the leg portion 232 of the heat dissipation member 219 is disposed on the groove portion of the frame 41.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus 1 according to the present embodiment. In the following description, the vertical direction of the image forming apparatus 1 is the arrow Z direction, and the horizontal direction shown in the figure, which is one of the horizontal directions orthogonal to the arrow Z direction, is the depth orthogonal to the arrow X direction, the arrow Z direction, and the arrow X direction. The direction is described as an arrow Y direction.

  The image forming apparatus 1 is, for example, a copier or a multifunction machine. The image forming apparatus 1 includes a paper storage unit 12 that stores recording paper P, and a paper processing unit 14 that is provided on the paper storage unit 12 and that forms and fixes images on the recording paper P supplied from the paper storage unit 12. A document reading unit 16 provided on the sheet processing unit 14 for reading the document G, and a control unit (not shown) provided in the sheet processing unit 14 for controlling the operation of each unit of the image forming apparatus 1. Yes.

  The paper storage unit 12 is provided with a delivery roll 22 that feeds the recording paper P to a conveyance path 18 provided in the image forming apparatus 1. A pair of transport rolls 24 that transport the recording paper P one by one are provided on the transport path 18 downstream of the feed rolls 22. The conveyance path 18 is provided in the arrow Z direction with the lower side in FIG. 1 as the upstream side and the upper side in FIG. 1 as the downstream side.

  The paper processing unit 14 includes a housing 14A, an image forming unit 30 that is disposed to face the conveyance path 18 in the housing 14A and forms a toner image (developer image) on the recording paper P, and a center in the housing 14A. And an exposure unit 40 (exposure device) for forming an electrostatic latent image on the photoreceptor 36 of the image forming unit 30 and a fixing unit 50 for fixing the toner image on the recording paper P. Further, the sheet processing unit 14 includes an intake unit 60 provided on the front side in the arrow Y direction in the housing 14A, and an exhaust unit 100 provided on the back side in the arrow Y direction in the housing 14A.

  On the upper part of the housing 14A, a side wall 15 that is a YZ surface standing on the right side in the arrow X direction with respect to the conveyance path 18, and an XZ standing perpendicular to the side wall 15 in the arrow Y direction A side wall 17 that is a surface, and an upper wall 19 having an inclined wall 19 </ b> A that is an XY plane connected to the lower end of the side wall 15 and the lower end of the side wall 17 and is inclined toward the side wall 15 are provided. Then, the recording paper P on which the toner image is fixed is discharged to a discharge unit 28 that is a space surrounded by the side wall 15, the side wall 17, and the upper wall 19. A front cover (not shown) that can be opened and closed is provided on the front side in the arrow Y direction of the housing 14A (that is, the front side of the image forming apparatus 1).

  As shown in FIG. 1, a pair of alignment rolls 26 are provided on the upstream side of the conveyance path 18 to temporarily stop the recording paper P and send the recording paper P to a transfer position described later at a predetermined timing. Yes. Further, on the downstream side of the transport path 18, a pair of lower discharge rolls 56 and upper discharge rolls 58 are provided for discharging the recording paper P on which the toner image is fixed to the discharge unit 28. Note that an accumulation plate for accumulating sheets can be attached to the position of the side wall 15 between the lower discharge roll 56 and the upper discharge roll 58 as necessary.

  A double-sided conveyance unit 80 that conveys and inverts the recording paper P for image formation on both sides of the recording paper P is attached to the left side surface of the housing 14A. The double-sided conveyance unit 80 is provided with a double-sided conveyance path 82. Further, the double-sided conveyance path 82 is provided with a plurality of conveyance rolls 84 for conveying the recording paper P fed from the upper discharge roll 58 toward the alignment roll 26. A gap 86 is formed between the housing 14A and the duplex conveyance unit 80, and outside air can flow into the housing 14A from the gap 86.

  A high voltage power source 92 is provided below the exposure unit 40, and a toner cartridge 94 containing black toner supplied to the image forming unit 30 is mounted or attached above the exposure unit 40. It is provided so that it can be detached. Further, a wall portion 96 is erected on the right side of the intake portion 60, and a low voltage power supply portion 98 is provided on the wall portion 96 at a position facing the intake portion 60. The high voltage power supply unit 92 and the low voltage power supply unit 98 supply power to each unit of the image forming apparatus 1.

  FIG. 2 is a schematic configuration diagram of the image forming unit 30 of FIG. As shown in FIG. 2, the image forming unit 30 includes a photoconductor cartridge 32 that has a photoconductor 36 and is arranged on the upper side, a developing cartridge 34 that is arranged on the lower side of the photoconductor cartridge 32, and the photoconductor cartridge 32. And a shutter member 38 movably provided on the side. The exposure light L emitted from the exposure unit 40 irradiates the outer peripheral surface of the photoconductor 36 through a passage 43 formed by the bottom wall of the photoconductor cartridge 32 and the top wall of the developing cartridge 34.

  The photosensitive cartridge 32 is provided so as to be rotatable in an arrow + R direction (clockwise direction in the drawing), and after charging, an electrostatic latent image is formed on the outer peripheral surface by irradiation with exposure light L from the exposure unit 40 (see FIG. 1). The formed photosensitive member 36, the charging roll 33 for charging the outer peripheral surface of the photosensitive member 36, the erase lamp 35 for irradiating light to the outer peripheral surface of the photosensitive member 36 after the transfer of the electrostatic latent image, and after the erase lamp irradiation And a cleaning member 37 for cleaning the outer peripheral surface of the photosensitive member 36.

  The developing cartridge 34 includes a developing roll 42 that develops the electrostatic latent image on the outer peripheral surface of the photosensitive member 36 into a toner image with the developer K (including toner). The developing roll 42 is disposed to face the outer peripheral surface of the photoreceptor 36. A first transport member 45 and a second transport member 46 that stir the developer K stored in the developer storage chamber 44 while transporting the developer K in the axial direction are provided below the developing roll 42. Further, a toner supply unit 48 is provided on the right side of the developer storage chamber 44. The toner is supplied from the toner supply unit 48 to the developer storage chamber 44 by the rotation of the supply member 47 provided between the developer storage chamber 44 and the toner supply unit 48.

  Here, the shutter member 38 is movably provided between a position covering the photoconductor 36 and a position exposing the photoconductor 36 (arrow-S direction or arrow + S direction). When the image forming unit 30 is detached from the image forming apparatus 1, the shutter member 38 covers the outer peripheral surface of the photoreceptor 36. When the image forming unit 30 is mounted on the image forming apparatus 1, the shutter member 38 exposes the outer peripheral surface of the photosensitive member 36 toward the conveyance path 18 in FIG. 1. When the image forming unit 30 is mounted on the image forming apparatus 1 and the photosensitive member 36 is exposed, the shutter member 38 is disposed between the photosensitive member cartridge 32 and the fixing unit 50.

  Returning to FIG. 1, the exposure unit 40 is screwed to a frame 41 (housing support member) made of metal (for example, iron or aluminum). The frame 41 supports the casing of the exposure unit 40 and is attached to a rib (not shown) of the exposure unit 40. The light emitted from the exposure unit 40 is irradiated as the exposure light L on the outer peripheral surface of the photoreceptor 36. As a result, an electrostatic latent image corresponding to the image data is formed on the outer peripheral surface of the photoreceptor 36. The configuration of the exposure unit 40 and the frame 41 will be described later.

  A transfer roll 49 to which a voltage having a polarity opposite to the polarity of toner (for example, minus) is applied is provided at a position facing the outer peripheral surface of the photoreceptor 36 with the conveyance path 18 interposed therebetween. Here, the inner side of the photosensitive member 36 is grounded, and a voltage having a polarity opposite to that of the toner (for example, minus) is applied to the transfer roll 49, so that the gap between the outer peripheral surface of the photosensitive member 36 and the transfer roll 49 is applied. A potential difference occurs. Due to this potential difference (electric field), the toner image present on the outer peripheral surface of the photoconductor 36 after development is transferred onto the recording paper P.

  The fixing unit 50 includes a heating roll 52 provided with a heater therein, and a pressure roll 54 that is disposed to face the outer peripheral surface of the heating roll 52 and presses the recording paper P toward the heating roll 52. In the fixing unit 50, the recording paper P is sandwiched between the heating roll 52 and the pressure roll 54 to heat and press the recording paper P and fix the toner image on the recording paper P.

  The document reading unit 16 includes a document transport device 74 that automatically transports the documents G placed on the document table 72 one by one, and a platen glass on which a single document G is placed below the document transport device 74. 76 and a document reading device 78 that can move or stop in the X direction below the platen glass 76 and reads the document G on the platen glass 76.

  The document transport device 74 includes a feed roll 71 that feeds the document G one by one and an automatic transport path 75 in which a plurality of pairs of transport rolls 73 are arranged. A part of the automatic transport path 75 is a recording sheet P. Is arranged so as to pass over the platen glass 76. The document reading device 78 reads the read document G conveyed by the document conveying device 74 in a state of being stationary below the left end portion of the platen glass 76 or moves on the platen glass 76 while moving in the arrow X direction. Read G.

  FIG. 3 is a schematic configuration diagram of the intake unit 60 and the exhaust unit 100. FIG. 4 is an explanatory view showing the flow of air from the front cover to the intake section 60.

  First, the intake section 60 will be described. In FIG. 3, the intake section 60 includes an intake fan 62 that intakes air from the outside of the image forming apparatus 1 and an air duct 64 that is an example of a guide member that is attached to and integrated with the intake fan 62. The air duct 64 is formed with a curved wall 64A, which is a side wall curved toward the photoreceptor 36, and an opening 64B that opens to the XZ plane and the YZ plane.

  On the other hand, as shown in FIG. 4, an opening 21 </ b> A penetrating in the arrow Z direction is formed at the lower end of the front cover 21. The outside air can flow inside 21. An inner cover 23 is provided inside the front cover 21 (inside the image forming apparatus 1).

  The inner cover 23 is formed in a hollow rectangular parallelepiped shape, and a plurality of louvers 25 that allow air to flow into the inner cover 23 are formed in the lower portion of the front wall 23A of the inner cover 23. The plurality of louvers 25 are formed in a slit shape. Further, a rib 27 protruding to the front cover 21 in the arrow Y direction is provided on the front wall 23A of the inner cover 23. Thereby, the air flowing in from the opening 21 </ b> A flows into the inner cover 23 through the plurality of louvers 25.

  Further, an opening 29 that opens toward the inside of the image forming apparatus 1 is formed in the upper portion of the rear wall 23B of the inner cover 23. An intake fan 62 is attached to the opening 29. As a result, when the intake fan 62 starts intake, air flows from the opening 21 </ b> A of the front cover 21 to the opening 29 via the louver 25 of the inner cover 23, and inside the image forming apparatus 1 via the air duct 64. Sent to.

  Next, the exhaust part 100 will be described. As shown in FIG. 3, the exhaust unit 100 is arranged side by side with the end of the shutter member 38 that covers the photoconductor 36 in the direction of the arrow X. The exhaust unit 100 includes an inflow duct unit 102 through which air in the image forming apparatus 1 flows, a discharge duct unit 104 disposed on the back side in the arrow Y direction with respect to the inflow duct unit 102, and the exhaust duct unit 104. An exhaust fan 106 for exhausting air and an exhaust cover 108 attached to a back panel (not shown) installed upright on the image forming apparatus 1 are provided.

  The inflow duct portion 102 has a bottom wall 102A that is formed in a substantially trapezoidal shape in a plan view and disposed on the XY plane. A side wall 102B and a side wall 102C are erected on the bottom wall 102A in the direction of arrow Z, and a partition wall 112 is erected at the center of the bottom wall 102A. The partition wall 112 divides the exhaust flow path into a first flow path 114 and a second flow path 116. The inflow duct portion 102 is covered with an inclined wall 19 </ b> A (see FIG. 1) attached to the upper side to form a cylindrical body, and air flows inside the closed first flow path 114 and second flow path 116. Flowing. The first flow path 114 is a cylindrical body surrounded by the bottom wall 102A, the side wall 102B, the partition wall 112, and the inclined wall 19A. The second flow path 116 is a cylindrical body surrounded by the bottom wall 102A, the partition wall 112, the side wall 102C, and the inclined wall 19A.

  The discharge duct section 104 is connected to the first discharge duct member 140 to which the inflow duct section 102 is connected, and the second odor of the recording paper P connected to the upper surface of the first discharge duct member 140 and discharged to the discharge section 28 is passed through. And a discharge duct member 146. The first discharge duct member 140 includes a first duct 142 connected to the first flow path 114 and a second duct 144 connected to the second flow path 116. With this configuration, when the exhaust fan 106 is operated, air is discharged from the first duct 142, the second duct 144, and the second discharge duct member 146 to the outside of the image forming apparatus 1 through the exhaust cover 108.

  FIG. 5 is a schematic block diagram of the exposure unit 40 and the frame 41 of FIG.

  The exposure unit 40 includes a housing 150, a semiconductor laser 151, a collimator lens 154, a cylindrical lens 152, an optical deflector 153, an imaging lens 155, a glass plate 156, a top plate 160, a printed circuit board 213, and a driving IC 215. . By screwing the top plate 160 onto the housing 150, the inside of the housing 150 is sealed. A side wall 157 is provided along the edge of the housing 150, and a glass plate 156 that transmits laser light is provided on the side wall 157 at a position facing the photoconductor 36. Laser light emitted from the semiconductor laser 151 is deflected and scanned by an optical deflector 153 via a collimator lens 154 and a cylindrical lens 152, and exposed to the outer peripheral surface of the photoreceptor 36 via an imaging lens 155 and a glass plate 156. Irradiated as L. As a result, an electrostatic latent image corresponding to the image data is formed on the outer peripheral surface of the photoreceptor 36.

  Here, the configuration of the optical deflector 153 will be described. FIG. 6 is a view showing a cross section taken along the line AA of FIG.

  The optical deflector 153 includes a polygon mirror 201 as a polygon mirror, a rotating body 202 that rotates at high speed, and a sleeve 204 (rotating shaft bearing portion) that is sealed at the lower end and supports the rotating shaft 203 of the rotating body 202. ing. The rotating body 202 includes a rotating body main body 206 to which a polygon mirror 201, a rotating shaft 203, and a drive magnet 205 are attached. The polygon mirror 201, the rotating shaft 203, and the drive magnet 205 are attached to the rotating body main body 206 by press-fitting or bonding, for example. The polygon mirror 201 is fixed to the rotating body main body 206 by a leaf spring 207 and a washer 208.

  The sleeve 204 has a radial bearing portion 209 </ b> A that supports the radial direction of the rotating shaft 203 and a thrust bearing portion 209 </ b> B that supports the thrust direction of the rotating shaft 203. The gap between the rotary shaft 203 and the radial bearing portion 209A is about several μm to several tens of μm, and the gap is filled with lubricating oil. The thrust bearing portion 209 </ b> B is a pivot bearing formed of a lower end portion of the rotating shaft 203 and a sliding member (for example, a thermoplastic industrial resin agent) 210. The axial direction of the rotating body 203 is supported by the thrust bearing portion 209B. The sliding member 210 is sealed with a lid member 211.

  In addition, an armature coil 212 is attached to the sleeve 204 at a position facing the drive magnet 205 in the radial direction. The armature coil 212 and the drive magnet 205 constitute a motor 251. The armature coil 212 is attached to the sleeve 204 by, for example, press fitting or adhesion.

  A printed circuit board 213 is attached to the sleeve 204 by, for example, caulking. A magnet position detector 214 (for example, a Hall element) is mounted on the printed board 213 at a position facing the armature coil 212. In addition, a drive IC 215 and a connector 216 are mounted on the printed circuit board 213.

  The motor 251 in the present embodiment is an outer rotor type in which a magnetic gap is provided in the radial direction and the drive magnet 205 is laid out outside the armature coil 212. The rotating body 202 refers to a signal output from the magnet position detector 214 by the magnetic field of the driving magnet 205 as a position signal, and rotates by switching the excitation of the armature coil 212 by the driving IC 215. A harness (not shown) is connected to the connector 216, and power is supplied from the main body of the image forming apparatus 1, the motor is started and stopped, and control signals such as the number of rotations are input and output via the connector 216 and the harness.

  The optical deflector 153 configured as described above is housed in the housing 150. The printed board 213 is fixed to the casing 150 by fixing the screw holes 213A formed at the end of the printed board 213 to the ribs 150B formed on the floor 150A of the casing 150 with screws 251. The floor 150A of the housing 150 has an exposure hole 217 that exposes the lower end surface of the thrust bearing 209B to the outside. The heat radiating member 219 is fastened to the lid member 211 by screw holes and bolts 218 formed in the lid member 211 provided in the thrust bearing portion 209B.

  The heat dissipation member 219 is provided between the bottom 150 </ b> A of the housing 150 and the frame 41. The bottom portion 150 </ b> A of the housing 150 is provided approximately 1 cm above the frame 41. The heat dissipating member 219 is a single plate spring (elastic member), for example, a sheet metal (for example, spring steel, stainless steel, brass, phosphor bronze, etc.) that has been subjected to bending processing, or aluminum molded by a die casting method. Composed of materials. Further, as shown in FIG. 6, the side shape of the heat dissipation member 219 is a “π” shape. The heat dissipation member 219 includes a substantially horizontal support portion 231, a substantially horizontal leg portion 232, and a shoulder portion 233 that connects the support portion 231 to the leg portion 232, and a bolt 218 is passed through the center of the support portion 231. A hole 234 is provided.

  When the housing 150 is fixed to the frame 41 with a plurality of screws 250, the leg portions 232 of the heat dissipation member 219 come into contact with the frame 41. That is, in the heat dissipation member 219, the leg portion 232 is in contact with the frame 41, and the support portion 231 is in contact with the bearing portion of the rotating shaft 203, that is, the sleeve 204. Thereby, the heat generated by the rotation of the rotating shaft 203 is directly transmitted to the heat radiating member 219 and then transmitted to the frame 41. Therefore, the heat generated inside the housing 150 due to the rotation of the rotating shaft 203 can be efficiently radiated to the outside. Further, even if the amount of heat generated due to the high-speed rotation of the polygon mirror 201 increases, the temperature rise inside the housing 150 can be suppressed.

  Moreover, since the leg part 232 contacts the frame 41 in a plane, the contact stability is increased as compared with the case of line contact. Further, heat can be transferred to the frame 41 more efficiently than in the case of line contact. In addition, the leg part 232 may not be flat but may be constituted by a bellows-like bent part in which irregularities are alternately arranged. In this case, the leg portion 232 makes line contact with the frame 41.

  The frame 41 is made of iron, aluminum, or the like, and a duct 170 (an escape portion) for flowing air is formed at a position facing the support portion 231 of the heat radiating member 219. In the duct 170, air exhausted from the intake section 60 and air entrained in the air flow flow. Since the air flowing through the duct 170 touches the support portion 231 and the shoulder portion 233 of the heat radiating member 219 and the frame 41, the heat radiating member 219 and the frame 41 are efficiently cooled as compared with the case where the duct 170 is not provided.

  Returning to FIG. 5, the frame 41 has been subjected to bending processing, and includes a mounting surface 171 to which the exposure unit 40 is mounted, a side surface 172 that faces the photoconductor 36 along an end of the mounting surface 171, and an upper surface 173. It has. The exposure unit 40 is screwed to the mounting surface 171. The mounting surface 171 is provided with a screw hole 174 for screwing to a rib (not shown) of the image forming apparatus 1. The side surface 172 on the side of the photoconductor 36 is formed at a position on the mounting surface 171 closer to the photoconductor 36 than the duct 170 in parallel with the longitudinal axis direction (Y direction in FIG. 5) of the photoconductor 36. Further, the side surface 172 on the photoconductor 36 side is formed lower than the height from the lower end of the casing 150 of the exposure unit 40 to the lower end of the glass plate 156. As a result, the laser light transmitted to the photoconductor 36 through the glass plate 156 is not blocked by the side surface 172 on the photoconductor 36 side. Further, the duct 170 is formed on the mounting surface 171 by, for example, pressing or drawing. The duct 170 includes a single first duct 170A extending in the Y direction (that is, the depth direction from the front surface to the back surface of the image forming apparatus 1 or the axial direction of the photosensitive member 36) and the X direction (that is, the left side of the image forming apparatus 1). Three second ducts 170B extending in the direction from the surface to the right side). The shape of the duct 170 is not limited to the shape shown in FIG. Air from the intake section 60 flows into the duct 170. Air from the intake section 60 flows through the first duct 170A and the second duct 170B, and finally travels toward the exhaust section 100 (not shown). In the second duct 170B, the air pushed out by the air from the intake section 60 or the air involved in the air flow from the intake section 60 flows into the first duct 170A.

  FIG. 7 is a diagram showing the relationship between the frequency of the sleeve 204 generated by the two rotation modes of the motor 251 and the frequency response function of the housing 150. In FIG. 7, the vertical axis represents inertance [(m / s ^ 2) / N] (response acceleration with respect to external force), and the horizontal axis represents the frequency of vibration of the casing 150. The frequency response function of the housing 150 is calculated in advance by modal analysis or simulation. For example, in a modal analysis, an accelerometer is attached to the housing 150, and a frequency response function of the housing 150 is obtained by measuring a response acceleration of the housing 150 when an external force assuming an excitation source is applied.

  The motor 251 has a plurality of rotation modes M1 and M2 in order to correspond to the print output speed or a plurality of image resolutions. It is assumed that the rotation speed in the rotation mode M2 is higher than the rotation speed in the rotation mode M1. The motor 251 may have two or more rotation modes. As described above, the housing 150 that accommodates the motor 251 is fixed to the frame 41 by the plurality of screws 250, so that a natural frequency exists at the bottom 150 </ b> A of the housing 150.

  As shown in FIG. 7, for example, when the motor 251 rotates in the rotation mode M <b> 2, the frequency of the sleeve 204 generated by the rotation of the motor 251 is close to or coincides with the natural frequency of the casing 150. May resonate with the vibration of the sleeve 204. In this case, the vibration of the housing 150 increases, and the irradiation position of the laser beam on the photosensitive member 36 is blurred. This blurring of the irradiation position leads to deterioration of image quality.

  Therefore, in the present embodiment, the natural vibration of the casing 150 is changed as shown in FIG. 7 by changing the support force to the sleeve 204 by the heat radiating member 219 disposed between the casing 150 and the frame 41. The number is shifted so as not to be close to the frequency of the sleeve 204 generated by the rotation of the motor. The natural frequency of the housing 150 shifts to the right when the support force of the heat dissipation member 219 increases, and shifts to the left when the support force of the heat dissipation member 219 decreases. Here, the principle by which the supporting force of the heat radiating member 219 varies the natural frequency of the housing 150 will be described. Since the housing 150 is fixed to the frame 41 with screws 250, it can be assumed that the housing 150 is a beam supported at both ends. Since the supporting force of the heat radiating member 219 is loaded at substantially the center of the beam, when the supporting force of the heat radiating member 219 varies, the spring coefficient of the beam is substantially changed. On the other hand, the natural frequency of the beam (housing 150) is proportional to the square root of the spring coefficient of the beam. Accordingly, the supporting force of the heat radiating member 219 varies the natural frequency of the housing 150.

  FIG. 8A is a diagram illustrating an example of the configuration of the heat dissipation member 219 when the heat dissipation member 219 is viewed from above. FIG. 8B is a diagram illustrating a B1-B1 cross section of FIG. FIG. 8C illustrates a cross section taken along line C1-C1 in FIG. FIG. 8D is a diagram illustrating a state in which the heat dissipating member 219 of FIG. 8A is rotated 90 degrees clockwise or counterclockwise. FIG. 8E is a diagram illustrating a first modification of the heat dissipation member 219. FIG. 8F is a diagram illustrating a second modification of the heat dissipation member 219.

  As shown in FIG. 8A, the heat dissipating member 219 is a leaf spring, and a hole 234 through which the bolt 218 is passed is provided at the center, and the pair of contact portions 301 is formed in the Y direction (image formation). The pair of contact portions 302 extends from the support portion 231 in the X direction (the direction from the left side surface to the right side surface of the housing 14A of the image forming apparatus 1). . Each of the contact portions 301 and 302 is made of the same material, and includes a shoulder portion 233 and a leg portion 232. The width W1 of the contact portion 301 is shorter than the width W2 of the contact portion 302.

  As shown in FIG. 8B, the leg portion 232 of the contact portion 302 is in contact with the frame 41, and the support portion 231 is disposed at a position facing the duct 170. On the other hand, as shown in FIGS. 8A and 8C, the pair of contact portions 301 are disposed above the duct 170 in parallel with the duct 170. Accordingly, the leg portion 232 of the contact portion 301 does not contact the frame 41.

  As shown in FIGS. 8A and 8B, in the state where the leg portion 232 of the contact portion 302 is in contact with the frame 41, the casing 150 resonates with the vibration of the sleeve 204 caused by the rotation in the rotation mode M2. In this case, as shown in FIG. 8D, the heat dissipating member 219 in FIG. 8A is rotated 90 degrees clockwise or counterclockwise. The heat radiating member 219 is rotated by the manufacturer in the manufacturing process of the image forming apparatus 1.

  In the case of FIG. 8D, the leg portions 232 of the pair of contact portions 301 are in contact with the frame 41. Since the width W1 of the contact portion 301 is shorter than the width W2 of the contact portion 302, the spring coefficient of the contact portion 301 is smaller than the spring coefficient of the contact portion 302. Therefore, the supporting force when the supporting force to the sleeve 204 by the heat radiating member 219 is as shown in FIG. For this reason, the natural frequency of the housing 150 shifts to the left in FIG. 7, and resonance due to vibration of the housing 150 and the sleeve 204 is avoided.

  On the other hand, when the casing 150 resonates with the vibration of the sleeve 204 caused by the rotation of the rotation mode M2 in the state of FIG. 8D, as shown in FIG. The heat radiating member 219 is rotated 90 degrees clockwise or counterclockwise. Thereby, the support force to the sleeve 204 by the heat radiating member 219 is also strong in the case of FIG. For this reason, the natural frequency of the housing 150 is shifted to the right in FIG. 7, and resonance due to vibration of the housing 150 and the sleeve 204 is avoided.

  In FIG. 8A, two pairs of contact portions 301 and 302 are formed on the heat dissipating member 219. However, as shown in FIG. 8E, two or more pairs of contact portions may be formed. . In this case, the width of each contact portion is changed. For example, in the example of FIG. 8E, the width W3 is longer than the width W1 and shorter than the width W2. Further, for example, as shown in FIG. 8F, the heat dissipating member 219 may be configured by overlapping a plurality of rectangular leaf springs 219A and 219B having different widths, that is, different contact portions 301 and 302. In FIG. 8F, the leaf spring 219A is disposed parallel to the Y direction and the leaf spring 219B is disposed parallel to the X direction. However, the leaf spring 219A and the leaf spring 219B may be overlapped in the same direction. . Further, the leaf springs 219A and 219B may be configured by springs having different Young's moduli. For example, the leaf spring 219A may be made of spring steel, and the leaf spring 219B may be made of stainless steel.

  FIG. 9A is a diagram illustrating a third modification of the heat dissipation member 219. FIG. 9B is a diagram illustrating a B2-B2 cross section of FIG. FIG. 9C illustrates a cross section taken along line C2-C2 of FIG. FIG. 9D is a diagram illustrating a modification of the C2-C2 cross section in FIG. FIG. 9E is a diagram illustrating a fourth modification of the heat dissipation member 219.

  As shown in FIG. 9A, the heat dissipating member 219 is a leaf spring, and a hole 234 through which the bolt 218 is passed is provided at the center, and the pair of contact portions 301 is formed in the Y direction (image formation). The pair of contact portions 303 extends from the support portion 231 in the X direction (a direction perpendicular to the depth direction of the image forming apparatus 1). Each of the contact parts 301 and 303 is made of the same material, and is constituted by a shoulder part 233 and a leg part 232. The width W1 of the contact portion 301 is the same as the width W1 of the contact portion 303. The contact part 301 is longer than the contact part 303.

  In this case, the deflection amount of the heat radiation member 219 shown in FIG. 9B (that is, the height in the vertical direction from the leg portion 232 to the support portion 231 of the contact portion 303) is the same as that of the heat radiation member 219 shown in FIG. It is the same as the amount of deflection (that is, the height in the vertical direction from the leg portion 232 to the support portion 231 of the contact portion 301). On the other hand, as shown in FIGS. 9B and 9C, the length L <b> 2 of the contact portion 301 is longer than the length L <b> 1 of the contact portion 303. Since the spring coefficient of the leaf spring is inversely proportional to the cube of the length from the spring center (hole 234) to the end of the spring, the spring coefficient of the contact portion 301 is smaller than the spring coefficient of the contact portion 303. Therefore, the support force to the sleeve 204 by the heat radiating member 219 in FIG. 9C is weaker than the support force in the case of FIG.

  When the leg part 232 of the contact part 303 comes into contact with the frame 41 and the casing 150 resonates with the vibration of the sleeve 204 caused by the rotation of the rotation mode M2, the leg part 232 of the contact part 301 comes into contact with the frame 41. 9A is rotated 90 degrees clockwise or counterclockwise. In this case, the natural frequency of the housing 150 shifts to the right in FIG. 7 with respect to the vibration frequency of the sleeve 204 caused by the rotation of the rotation modes M1 and M2 shown in FIG. Resonance due to is avoided.

  In FIG. 9A, two pairs of contact portions 301 and 303 having the same width are formed on the heat radiating member 219. For example, as shown in FIG. The heat dissipating member 219 may be configured by overlapping a plurality of rectangular leaf springs 219C and 219D having 301 and 303. In FIG. 9E, the leaf spring 219C is disposed in parallel to the Y direction and the leaf spring 219D is disposed in parallel to the X direction. However, the leaf spring 219C and the leaf spring 219D may be stacked in the same direction. . Further, the leaf springs 219C and 219D may be constituted by springs having different Young's moduli. For example, the leaf spring 219C may be made of spring steel, and the leaf spring 219D may be made of stainless steel.

  9B and 9D, the thickness TH1 of the contact portion 303 may be configured to be thicker than the thickness TH2 of the contact portion 301. Note that the length of the contact portion 301 in FIG. 9D is L1. In this case, the contact portion 303 and the contact portion 301 have the same length but different thicknesses. Since the contact portion 303 is thicker than the contact portion 301, the spring coefficient of the contact portion 303 is larger than the spring coefficient of the contact portion 301. Therefore, the support force to the sleeve 204 by the contact portion 303 shown in FIG. 9B is stronger than the support force to the sleeve 204 by the contact portion 301 shown in FIG. 9D.

  FIG. 10A is a diagram illustrating an example of the configuration of the frame 41 when the heat radiating member 219 and the frame 41 are viewed from above. FIG. 10B is a view showing a DD cross section of FIG. 10A when the leg portion 232 of the heat radiating member 219 is disposed on the protruding portion of the frame 41. FIG. 10C is a diagram showing an EE cross section of FIG. 10A when the leg portion 232 of the heat radiating member 219 is disposed on the groove portion of the frame 41.

  The heat dissipating member 219 in FIG. 10A is a single rectangular (rectangular) leaf spring, and includes a support portion 231, a pair of leg portions 232, and a pair of shoulder portions 233 (that is, a pair of contact portions 301). ). As shown in FIG. 10A, the frame 41 may be formed with a protrusion 181 and / or a groove 182 on which the leg 232 of the heat dissipation member 219 is placed when the heat dissipation member 219 is rotated. The protrusion 181 and / or the groove 182 are formed by, for example, drawing or pressing the frame 41.

  As shown in FIG. 10B, when the leg portion 232 of the heat radiating member 219 is disposed on the protruding portion 181 of the frame 41, the leg portion 232 is less than the case where the leg portion 232 is not disposed on the protruding portion 181. The height H3 in the vertical direction from the portion 232 to the support portion 231, that is, the length of the heat radiation member 219 in the vertical direction to the sleeve 204 is shortened. That is, when the leg portion 232 is disposed on the projecting portion 181, the support force to the sleeve 204 by the heat radiating member 219 is stronger than when the leg portion 232 is not disposed on the projecting portion 181.

  For example, when the leg 232 is not disposed on the protrusion 181 and the casing 150 resonates with the vibration of the sleeve 204 caused by the rotation of the rotation mode M2, the leg 232 is disposed on the protrusion 181. The heat radiating member 219 may be rotated as described. In this case, the natural frequency of the housing 150 shifts to the right in FIG. 7, and resonance due to vibration of the housing 150 and the sleeve 204 is avoided.

  On the other hand, as shown in FIG. 10C, when the leg portion 232 of the heat radiating member 219 is disposed on the groove portion 182 of the frame 41, the leg portion 232 is less than the case where the leg portion 232 is not disposed on the groove portion 182. The height H4 in the vertical direction from the portion 232 to the support portion 231, that is, the length of the heat radiation member 219 in the vertical direction to the sleeve 204 is increased. That is, when the leg portion 232 is disposed on the groove portion 182, the support force to the sleeve 204 by the heat radiating member 219 is weaker than when the leg portion 232 is not disposed on the groove portion 182.

  For example, when the leg 232 is not disposed on the leg 182 and the casing 150 resonates with the vibration of the sleeve 204 caused by the rotation of the rotation mode M2, the leg 232 is disposed on the leg 182. The heat radiating member 219 may be rotated as described. In this case, the natural frequency of the housing 150 shifts to the left in FIG. 7, and resonance due to vibration of the housing 150 and the sleeve 204 is avoided.

  In FIG. 10A, the support force of the heat radiation member 219 to the sleeve 204 can be changed by arranging the leg portion 232 on the protruding portion 181 and / or the groove portion 182. Further, when the heat radiating member 219 shown in FIG. 10A is used, the duct 170 may not be formed in the frame 41.

  Further, instead of the heat radiating member 219 in FIG. 10A, the heat radiating member 219 shown in FIG. 8A, FIG. 8E, FIG. 8F, FIG. 9A, or FIG. May be used. In this case, the supporting force of the heat radiating member 219 to the sleeve 204 can be changed by arranging the leg portion 232 on the protruding portion 181 and / or the groove portion 182, and the heat radiating member 219 should be rotated and used. It can also be changed by selecting the contact portion.

  As described above, according to the present embodiment, the frame 41 and the heat radiating member 219 are configured to be able to change the support force for supporting the sleeve 204 by rotating the heat radiating member 219. Specifically, the heat dissipating member 219 has a plurality of pairs of contact portions having different widths or lengths in order to change the spring coefficient. Alternatively, the heat radiating member 219 is configured by overlapping a plurality of elastic members having at least one of width, length, thickness, and Young's modulus. On the other hand, the frame 41 includes a duct 170 that prevents another pair of contact portions from contacting the frame 41 when a pair of contact portions contact the frame 41. Further, the frame 41 has a protrusion 181 and / or a groove 182 for changing the amount of deflection of the heat dissipation member 219.

  Therefore, resonance that occurs when the natural frequency of the casing 150 of the exposure unit 40 approaches the vibration frequency of the sleeve 204 can be avoided.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Paper accommodating part 14 Paper processing part 16 Document reading part 30 Image forming unit 36 Photoconductor 40 Exposure unit 41 Frame 150 Case 153 Optical deflector 170 Duct 201 Polygon mirror 203 Rotating shaft 204 Sleeve 219 Heat radiation member

Claims (6)

An optical deflector having a rotating shaft that rotates a polygon mirror that exposes and scans light to the photosensitive member and a rotating shaft bearing that supports the rotating shaft, and the optical deflector are housed and the rotation of the optical deflector An exposure apparatus having a housing in which an exposure hole for exposing the shaft bearing portion is formed;
A housing support member for supporting the housing;
A heat dissipating member disposed between the housing and the housing support member and supported between the rotary shaft bearing portion and the housing support member so as to be in contact with the housing support member;
The image forming apparatus, wherein the housing support member and the heat radiating member are configured to change a support force for supporting the rotating shaft bearing portion by rotating the heat radiating member. The heat radiating member includes a plurality of contact portions that can come into contact with the housing support member, and a support portion that rotatably supports the rotating shaft bearing portion,
The housing support member includes an escape portion so that when one contact portion comes into contact with the housing support member, the other contact portion does not come into contact with the housing support member,
The image forming apparatus according to claim 1, wherein a width or length of the one contact portion is different from a corresponding width or length of the other contact portion. The heat dissipation member is configured by overlapping a plurality of members, and each member includes a contact portion that can contact the housing support member, and a support portion that rotatably supports the rotary shaft bearing portion,
The case support member includes an escape portion so that when one member is in contact with the case support member, the other member is not in contact with the case support member.
At least one of the width, thickness, length and Young's modulus of the contact portion of the one member is different from at least one of the corresponding width, thickness, length and Young's modulus of the contact portion of the other member. The image forming apparatus according to claim 1, wherein:   The image forming apparatus according to claim 2, wherein at least one of a projecting portion and a groove portion is formed on the housing support member.   The image forming apparatus according to claim 3, wherein at least one of a projecting portion and a groove portion is formed on the housing support member. The heat dissipating member includes a contact portion that can come into contact with the housing support member, and a support portion that rotatably supports the rotating shaft bearing portion,
The image forming apparatus according to claim 1, wherein at least one of a projecting portion and a groove portion is formed on the housing support member.

Images