JP2012159529A - Optical scanning device and image forming device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanning device that can prevent vibration from being transmitted from a housing to a folding back mirror without causing increase of assembling man hours and manufacturing costs.SOLUTION: The optical scanning device incorporates, in a housing 25, a deflector for deflecting a light beam emitted from a light source, an imaging lens for converting the light beam deflected by the deflector into constant speed scanning light, and a folding back mirror 32 for folding back the constant speed scanning light to guide the light to a photoreceptor. An elastic member 36 for filling a clearance of the folding back mirror 32, formed in two directions (lateral direction and vertical direction) except a reference plane to be attached to the housing 25, is attached to the folding back mirror 32.

Description

  The present invention relates to an optical scanning device for optically scanning a photoreceptor and an image forming apparatus such as a copying machine and a printer provided with the optical scanning device.

  In an image forming apparatus such as a copying machine or a printer, a photosensitive member whose surface is uniformly charged by a charger is optically scanned by an optical scanning device, and an electrostatic latent image corresponding to image information is formed on the surface. . The electrostatic latent image is developed by a developing device using toner as a developer to be visualized as a toner image. The toner image is transferred onto a sheet by a transfer device and then heated and heated by a fixing device. A series of image forming operations is completed by discharging the sheet having the toner image fixed thereon by being pressed and fixed on the sheet.

  By the way, an optical scanning device that optically scans a photoconductor to form an electrostatic latent image on the surface thereof includes a deflector such as a polygon mirror that deflects a light beam emitted from a light source, and light deflected by the deflector. An imaging lens that converts the beam into constant speed scanning light and a plurality of folding mirrors that fold back the constant speed scanning light and guide it to the photosensitive member are housed in a housing.

  Since the folding mirror used in such an optical scanning device is generally composed of a long mirror that is long in the main scanning direction, it is likely to vibrate due to vibrations of the image forming apparatus main body, the polygon mirror, and the like. When the folding mirror vibrates, the light beam moves up and down on the photosensitive member, and this causes a problem that the image is affected as a jitter.

  As a method for solving the above problem, it is generally performed that the resonance frequency of the folding mirror is shifted from the driving frequency of the polygon motor. The resonance frequency of the folding mirror deviates from the assumed resonance frequency. It is impossible to define the contact point between the folding mirror and the casing by narrowing the clearance between the folding mirror and the casing. Clearance will occur. For this reason, it is impossible to know whether or not the folding mirror and the housing are in contact with each other at locations other than the attachment reference, and if they are in contact, at which location they are in contact.

  Therefore, Patent Document 1 proposes a configuration in which one longitudinal end face of the reflection mirror (folding mirror) is held by an elastic member (contact member).

  Patent Document 2 proposes a configuration in which both end portions of the folding mirror and other predetermined positions are fixed with an adhesive that exhibits elasticity even in a cured state.

JP 2007-003726 A Japanese Patent Laid-Open No. 7-092210

  However, in the configuration proposed in Patent Document 1, since the short direction of the reflection mirror (folding mirror) is not regulated, elements that are unstable with respect to vibration remain.

  Further, the configuration proposed in Patent Document 2 has a problem that it takes a long time for the adhesive to harden and a jig for positioning is required.

  The present invention has been made in view of the above problems, and the object of the present invention is light that can suppress vibration from the housing to the folding mirror with a simple configuration without increasing the number of assembly steps or increasing the cost. An object of the present invention is to provide a scanning device and an image forming apparatus having the same.

  In order to achieve the above object, a first aspect of the present invention includes a deflector that deflects a light beam emitted from a light source, and an imaging lens that converts the light beam deflected by the deflector into constant-speed scanning light. In the optical scanning device in which a folding mirror that folds back the constant-speed scanning light and guides it to the photosensitive member is housed in the casing, the clearance formed in two directions other than the reference plane for mounting the folding mirror to the casing is filled. An elastic member is attached to the folding mirror.

  According to a second aspect of the present invention, in the first aspect of the present invention, the elastic member is attached to each of both ends of the folding mirror in the main scanning direction.

  An image forming apparatus according to a third aspect includes the optical scanning device according to the first or second aspect.

  According to the first aspect of the present invention, since the clearance formed in two directions other than the reference plane for attaching the folding mirror to the casing is filled with the elastic member attached to the folding mirror, the damping action of the elastic member This suppresses vibration from the housing to the folding mirror. In addition, since the folding mirror does not come into contact with the housing at a place other than the mounting reference surface, the resonance frequency of the folding mirror does not deviate from the assumed resonance frequency, and this resonance frequency is deflected by a polygon mirror or the like. It can be separated from the drive frequency of the device, and vibration due to resonance of the folding mirror can be suppressed. And since such an effect is acquired by the simple structure which only attaches an elastic member to a folding | return mirror, the increase in an assembly man-hour and a cost increase are not caused.

  According to the second aspect of the present invention, since the elastic members are respectively attached to both ends of the folding mirror in the main scanning direction, it is possible to suppress a significant increase in the number of parts and the number of assembly steps.

  According to the third aspect of the present invention, since the vibration of the folding mirror is suppressed, the vertical movement of the light beam on the photosensitive member is suppressed, and the occurrence of image defects such as jedder is prevented, and the high quality image is stabilized. Can be obtained.

1 is a side sectional view of an image forming apparatus (color laser printer) according to the present invention. It is a perspective view which removes and shows the cover of the optical scanning device concerning the present invention. 1 is a cross-sectional view of an optical scanning device according to the present invention. It is a perspective view of the folding mirror attaching part of the optical scanning device concerning the present invention. It is a top view of the A section of FIG. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is a perspective view of the folding mirror of the optical scanning device concerning the present invention.

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

[Image forming apparatus]
FIG. 1 is a cross-sectional view of a color laser printer as an embodiment of an image forming apparatus according to the present invention. 1M, a cyan image forming unit 1C, a yellow image forming unit 1Y, and a black image forming unit 1K are arranged in tandem at regular intervals.

  In each of the image forming units 1M, 1C, 1Y, and 1K, photosensitive drums 2a, 2b, 2c, and 2d, which are photosensitive members, are arranged, respectively, and around each of the photosensitive drums 2a to 2d, a charger 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c, 4d, transfer rollers 5a, 5b, 5c, 5d and drum cleaning devices 6a, 6b, 6c, 6d are arranged, respectively.

  Here, the photosensitive drums 2a to 2d are drum-shaped photosensitive members, and are rotationally driven at a predetermined process speed in a direction indicated by an arrow (clockwise) by a driving motor (not shown). The chargers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing devices 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (K) toner, respectively, and are formed on the photosensitive drums 2a to 2d. In addition, the toner of each color is attached to each electrostatic latent image to visualize each electrostatic latent image as a toner image of each color.

  The transfer rollers 5a to 5d are arranged so as to be able to contact the photosensitive drums 2a to 2d via the intermediate transfer belt 7 in the respective primary transfer portions. Here, the intermediate transfer belt 7 is stretched between a driving roller 8 and a tension roller 9 and is disposed on the upper surface side of each of the photosensitive drums 2a to 2d. The driving roller 8 is a secondary roller. The transfer unit is disposed so as to be in contact with the secondary transfer roller 10 via the intermediate transfer belt 7. A belt cleaning device 11 is provided in the vicinity of the tension roller 9.

  Incidentally, toner containers 12a, 12b, 12c, and 12d for supplying toner to the developing devices 4a to 4d are arranged in a line above the image forming units 1M, 1C, 1Y, and 1K in the printer main body 100. It is installed.

  In addition, below the image forming units 1M, 1C, 1Y, and 1K in the printer main body 100, four optical scanning devices (laser scanner units) 13 are arranged in parallel in the paper transport direction. A paper feed cassette 14 is detachably installed at the bottom of the printer main body 100 below the bottom. A plurality of sheets (not shown) are stacked and accommodated in the sheet cassette 14, and in the vicinity of the sheet cassette 14, a pickup roller 15 that extracts sheets from the sheet cassette 14, and the extracted sheets A feed roller 16 and a retard roller 17 are provided for separating the components and feeding them one by one to the conveyance path S.

  In addition, the conveyance path S extending in the vertical direction on the side of the printer main body 100 includes a conveyance roller pair 18 that conveys a sheet, and the secondary transfer counter roller 8 and the second roller at a predetermined timing after the sheet is temporarily held. A registration roller pair 19 is provided to be supplied to a secondary transfer portion that is a contact portion with the next transfer roller 10. Next to the transport path S, another transport path S ′ used for forming an image on both sides of the sheet is formed, and a plurality of reversing roller pairs 20 are appropriately used for the transport path S ′. Are provided at regular intervals.

  By the way, the conveyance path S arranged in the vertical direction on one side of the printer main body 100 extends to the paper discharge tray 21 provided on the upper surface of the printer main body 100, and the fixing device 22 and the discharge path are disposed in the middle. Paper roller pairs 23 and 24 are provided.

  Next, an image forming operation by the color laser printer having the above configuration will be described.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate at a predetermined process speed in the direction of the arrow (clockwise) in the image forming units 1M, 1C, 1Y, and 1K, and these photosensitive drums 2a. ˜2d are uniformly charged by the chargers 3a to 3d. Each optical scanning device 13 emits a light beam modulated by a color image signal for each color, irradiates the surface of each photosensitive drum 2a to 2d with each light beam, and each color on each photosensitive drum 2a to 2d. The electrostatic latent images corresponding to the color image signals are respectively formed.

  First, magenta toner is attached to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charged polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. The magenta toner image is moved in the direction indicated by the arrow in the primary transfer portion (transfer nip portion) between the photosensitive drum 2a and the transfer roller 5a by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied. Primary transfer is performed on the intermediate transfer belt 7 that is rotationally driven.

  The intermediate transfer belt 7 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred to the magenta toner image on the intermediate transfer belt 7 in the primary transfer portion in the same manner as described above.

  Similarly, yellow and black toners respectively formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1K on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 7, respectively. The images are sequentially superimposed at each primary transfer portion, and a full-color toner image is formed on the intermediate transfer belt 7. The transfer residual toner which is not transferred onto the intermediate transfer belt 7 and remains on the photosensitive drums 2a to 2d is removed by the drum cleaning devices 6a to 6d, and the photosensitive drums 2a to 2d are prepared for the next image formation. It is done.

  Then, in accordance with the timing at which the leading end of the full-color toner image on the intermediate transfer belt 7 reaches the secondary transfer portion (transfer nip portion) between the drive roller 8 and the secondary transfer roller 10, The sheet fed to the conveyance path S by the feed roller 16 and the retard roller 17 is conveyed to the secondary transfer unit by the registration roller pair 19. Then, a full-color toner image is collectively transferred from the intermediate transfer belt 7 to the sheet conveyed to the secondary transfer unit by the secondary transfer roller 10 to which a secondary transfer bias having a polarity opposite to that of the toner is applied. .

  Thus, the sheet on which the full-color toner image has been transferred is conveyed to the fixing device 22, and the sheet on which the full-color toner image has been fixed by being heated and pressurized and thermally fixed on the surface of the sheet. A pair of paper discharge rollers 23 and 24 are discharged onto the paper discharge tray 21 to complete a series of image forming operations. The transfer residual toner that is not transferred onto the sheet and remains on the intermediate transfer belt 7 is removed by the belt cleaning device 11, and the intermediate transfer belt 7 is prepared for the next image formation.

[Optical scanning device]
Next, the optical scanning device 13 according to the present invention will be described with reference to FIGS.

  2 is a perspective view showing the optical scanning apparatus according to the present invention with the cover removed, and FIG. 3 is a cross-sectional view of the optical scanning apparatus. The color laser printer shown in FIG. 1 has four optical scanning devices 13 described below arranged in parallel. However, since all of these configurations are the same, only one optical scanning device 13 will be described below. explain.

  The optical scanning device 13 has a housing 25 integrally formed in a rectangular box shape with resin, and a polygon mirror 26 that is a deflector and a polygon motor that rotationally drives this at the bottom of the housing 25. 27 is arranged. Although not shown, a laser diode as a light source is attached to the side of the housing 25, and a collimator lens and a cylindrical lens are arranged in the housing 25 along the light beam emitting direction from the laser diode. Has been.

  Further, as shown in FIG. 3, the housing 25 has first and second imaging lenses 28 and 29 for converting the light beam deflected by the polygon mirror 26 into constant speed scanning light, and constant speed scanning light. First to third folding mirrors 30, 31, and 32 that are folded and guided to the photosensitive drum 2 a (2 b to 2 d) are accommodated.

  Meanwhile, the illustrated optical scanning device 13 exposes and scans the photosensitive drum 2a of the magenta image forming unit 1M shown in FIG. 1. As shown in FIG. A cover 33 made of resin is attached, and an opening 33a through which scanning light passes is formed in the optical path connecting the third folding mirror 32 of the cover 33 and the photosensitive drum 2a.

  Thus, a light beam emitted from a laser diode (not shown) that is a light source in the optical scanning device 13 is collimated by a collimator lens (not shown), and then converges in the sub-scanning direction by a cylindrical lens (not shown). The light enters the polygon mirror 26 that is rotationally driven by the polygon motor 27.

  As described above, the light beam incident on the polygon mirror 26 is deflected by the polygon mirror 26, passes horizontally through the first imaging lens 28, and then is folded upward and vertically by the first folding mirror 30. It is folded back toward the third folding mirror 32 by the folding mirror 31. The light beam folded back by the second folding mirror 31 passes through the second imaging lens 29 and is then folded obliquely upward toward the photosensitive drum 2 a by the third folding mirror 32, and an opening formed in the cover 33. The photosensitive drum 2a is exposed and scanned by forming a spot that passes through the portion 33a toward the photosensitive drum 2a, forms an image on the photosensitive drum 2a, and moves at a constant speed in the main scanning direction.

  2 and FIG. 3 exposes and scans the photosensitive drum 2a of the magenta image forming unit 1M shown in FIG. 1, but the printer main body of the color laser printer shown in FIG. As described above, four similar optical scanning devices 13 are arranged in parallel in 100, and these four optical scanning devices 13 provide another cyan image forming unit 1C, yellow image forming unit 1Y, and Bralac image forming unit 1K. All of the four photosensitive drums 2a to 2d including the photosensitive drums 2b, 2c and 2d are exposed and scanned by the light beam.

  Here, a mounting structure of a third folding mirror (hereinafter simply referred to as “folding mirror”) 32 will be described with reference to FIGS.

  4 is a perspective view of a folding mirror mounting portion of the optical scanning device, FIG. 5 is a plan view of a portion A in FIG. 4, FIG. 6 is a sectional view taken along line BB in FIG. .

  The folding mirror 32 is a long mirror that is long in the scanning direction as shown in FIGS. 4 and 7, and both ends in the scanning direction (left and right direction) are made at a predetermined angle with respect to the housing 25 by metal leaf springs 34. It is elastically fixed in an inclined state.

  That is, as shown in FIGS. 4 to 6, holding brackets 35 bent in an L shape in a plan view are integrally formed at two locations of the housing 25 (fixed locations of the folding mirror 32). Reference numeral 35 denotes a vertical wall 35A that stands upright from the side wall 25A and the bottom wall 25B of the housing 25, and an inclined wall 35B that stands upright from the bottom wall 25B of the housing 25 at an angle (attachment angle of the folding mirror 32). It is configured. Here, the inner surface of the inclined wall 35B of each holding bracket 35 and the bottom wall 25B of the housing 25 constitute a reference surface for attaching the folding mirror 32 to the housing 25, and the inner surface and the housing of the inclined wall 35B. Positioning projections 35a and 25a are formed on the bottom wall 25B of the body 25 as shown in FIG.

  The plate springs 34 are bent into a Z shape, and the hemispherical projections 34a formed on the plate springs 34 abut against the folding mirror 32, so that both ends of the folding mirror 32 in the scanning direction (left and right direction) The holding bracket 35 is pressed against the inclined wall 35B. In addition, the front-end | tip part 34b of each leaf | plate spring 34 is bent at right angle.

  As shown in FIG. 6, the folding mirror 32 scans the projections 35 a and 25 a formed on the inner surface of the slope wall 35 </ b> B of each holding bracket 35 and the bottom wall 25 </ b> B of the housing 25. (Left and right direction) Positioned in a state where the two surfaces are in contact with each other, and fixed to the casing 25 by pressing both ends in the scanning direction (left and right direction) against the inclined wall 35B of each holding bracket 35 by the plate spring 34 as described above. Has been. When the folding mirror 32 is attached to the housing 25 in this manner, the horizontal direction shown in FIG. 5 is provided between both ends of the folding mirror 32 in the scanning direction (left-right direction) and the vertical wall 35A of each holding bracket 35. A clearance δ1 is formed, and a vertical clearance δ2 shown in FIG. 6 is formed between the folding mirror 32 and the tip portion 34b of each leaf spring 34 bent at a right angle.

  Thus, in the present embodiment, both ends of the folding mirror 32 in the main scanning direction (left-right direction) are arranged in two directions (left-right direction and up-down direction) other than the reference plane for attaching the folding mirror 32 to the housing 25. Elastic members 36 for filling the formed clearances δ1 and δ2 are attached. Here, as shown in FIG. 7, one elastic member 36 is attached to each end of the folding mirror 32 in the main scanning direction (left and right direction), and extends over the end surface of the folding mirror 32 and the upper and lower surfaces adjacent thereto. It is attached in a folded state in a U shape.

  As described above, in the optical scanning device 13 according to the present invention, the clearances δ1 and δ2 formed in two directions (left and right directions and up and down directions) other than the reference surface for attaching the folding mirror 32 to the housing 25 are the folding mirrors. Since the elastic members 36 are attached to both ends of the main scanning direction (left-right direction) 32, the vibration from the housing 25 to the folding mirror 32 is suppressed by the vibration control action of the elastic members 36. Further, since the folding mirror 32 does not come into contact with the housing 25 at a position other than the mounting reference surface, the resonance frequency of the folding mirror 32 does not deviate from the assumed resonance frequency. It can be separated from the drive frequency of the motor 27, and vibration due to resonance of the folding mirror 32 can be suppressed. And since such an effect is acquired by the simple structure which only attaches the elastic member 36 to the folding | return mirror 32, the increase in an assembly man-hour and a cost increase are not caused.

  In the present embodiment, the elastic member 36 is attached to each of both ends of the folding mirror 32 in the main scanning direction (left and right direction), so that it is possible to suppress a significant increase in the number of parts and the number of assembly steps.

  As described above, according to the optical scanning device 13 of the present invention, since the vibration of the folding mirror 32 is suppressed, the vertical movement of the light beam on the photosensitive drums 2a to 2d of the color laser printer shown in FIG. The occurrence of image defects such as jedder is prevented, and high-quality images can be stably obtained.

  Although the above description has been made on the mounting structure of one folding mirror of the optical scanning device, vibrations of these folding mirrors can be suppressed by employing the same mounting structure for the other folding mirrors. Although the present invention has been described with respect to a mode in which the present invention is applied to a color laser printer and an optical scanning device provided in the color laser printer, the present invention is not limited to a color printer and other arbitrary images including monochrome. Of course, the present invention can be similarly applied to the forming apparatus and the optical scanning device provided therein.

1M Magenta image forming unit 1C Cyan image forming unit 1Y Yellow image forming unit 1K Black image forming unit 2a to 2d Photosensitive drum (photoconductor)
3a to 3d charger 4a to 4d developing device 5a to 5d transfer roller 6a to 6d drum cleaning device 7 intermediate transfer belt 8 drive roller 9 tension roller 10 secondary transfer roller 11 belt cleaning device 12a to 12d toner container 13 optical scanning device 14 Paper cassette 15 Pickup roller 16 Feed roller 17 Retard roller 18 Transport roller pair 19 Registration roller pair 20 Transport roller pair 21 Paper discharge tray 22 Fixing device 23, 24 Paper discharge roller pair 25 Optical scanning device housing 25A Side wall of housing 25B Bottom wall of housing 25a Projection of housing 26 Polygon mirror 27 Polygon motor 28, 29 Imaging lens 30 to 32 Folding mirror 33 Cover 33a Cover opening 34 Plate spring 34a Plate spring projection 34b plate spring tip 35 holding bracket 35A retaining projection 36 elastic member 100 printer body S of the inclined surface wall 35a holding bracket of the vertical wall 35B holding bracket of the bracket, S 'conveying path δ1 lateral direction of the clearance δ2 vertical clearance

Claims (3)

A deflector that deflects the light beam emitted from the light source, an imaging lens that converts the light beam deflected by the deflector to constant-speed scanning light, and a folding mirror that folds the constant-speed scanning light and guides it to the photoconductor. In an optical scanning device housed in a housing,
An optical scanning device characterized in that an elastic member for filling a clearance formed in two directions other than a reference plane for attaching the folding mirror to the housing is attached to the folding mirror.   2. The optical scanning device according to claim 1, wherein one elastic member is attached to each of both ends of the folding mirror in the main scanning direction. An image forming apparatus comprising the optical scanning device according to claim 1.

Images