JP2011107388A - Optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variation in the position of a beam spot, due to the bending vibration of a folding mirror in an optical scanner in which a photoreceptor drum is irradiated with a laser beam for an image formation. <P>SOLUTION: Both end parts of the folding mirror 101 are fixed in the state where the reflection face of the folding mirror 101 is tilted and supported by two bottom face members 102a, 102b provided on the bottom face of an optical box of the optical scanner, and a vibration suppression fixture 104 is provided to press the folding mirror 101 in the direction of the bottom face of the optical box in a prescribed position in the longitudinal direction between the two bottom face members 102a, 102b of the folding mirror 101. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  In a conventional image forming apparatus, many optical scanning apparatuses that form an image by irradiating a photosensitive drum with a laser beam use a reflection mirror (folding mirror) for bending an optical path. If the angle accuracy of the folding mirror is not sufficiently high, the beam spot applied to the photosensitive drum varies in the sub-scanning direction, and the image position varies with respect to the paper. In order to correct this variation, adjustment is required for each machine, resulting in a decrease in mass production efficiency. In addition, when the position irradiated on the photosensitive drum is changed, the optical path length is changed and the beam spot diameter is changed, which also affects the image quality degradation.

  Conventionally, the mirror holding seat surface has been formed with very high positional accuracy in the optical box. However, if the mirror holding seat surface is not sufficiently held by the mirror holding seat surface, the mirror angle will shift when the folding mirror is attached. was there.

  To deal with such problems, Patent Document 1 discloses a technique for suppressing the rotational moment of the folding mirror by devising the folding mirror support position, direction, and pressing force in order to suppress the mirror angle variation in the folding mirror holding portion.

  Patent Document 2 discloses a relational expression between the pressing force of the folding mirror support portion and the mass of the folding mirror for suppressing the vibration of the folding mirror.

  However, in the invention described in Patent Document 1, fluctuations in the beam spot position in the sub-scanning direction due to bending vibration that vibrates so that the folding mirror bends cannot be suppressed. Further, in the invention described in Patent Document 2, it is possible to suppress vibration when the pressing force of the folding mirror support portion is not sufficient, but when the folding mirror is supported by the supporting portion with sufficient pressing force. It did not suppress the bending vibration of the folding mirror.

  The present invention has been made in view of the above problems in the prior art, and an optical scanning device and an optical scanning device that improve the image quality by suppressing the bending vibration of the folding mirror to reduce the change amount of the beam spot position. An object of the present invention is to provide an image forming apparatus including the above.

The present invention provided to solve the above problems is as follows.
[1] A light source (light source unit 12), a light deflector (deflection scanning unit 14) for scanning a light beam emitted from the light source, and a light beam deflected and scanned by the light deflector The light source, the optical deflector, and the folding mirror are mounted in an optical box (optical box 11) having a single or a plurality of long folding mirrors (folding mirror 101) for exposure and scanning. In the optical scanning device, both end portions of the folding mirror are supported with two reflecting members (seat surface members 102a and 102b) provided on the bottom surface of the optical box inclining the reflecting surface of the folding mirror. (Fixed by leaf springs 103a and 103b), and the folding mirror is pressed toward the bottom surface of the optical box at a predetermined position in the longitudinal direction between the two support members of the folding mirror. An optical scanning device having a vibration suppression jig (vibration suppression jig 104) (FIG. 1).
[2] The optical scanning device according to [1], wherein the vibration suppression jig is detachably mounted in the optical box.
[3] The optical scanning device according to [1] or [2], wherein the vibration suppressing jig includes an elastic member (elastic layer 105b) at a contact portion with the folding mirror (FIG. 4). .
[4] The optical scanning device according to any one of [1] to [3], wherein a force for pressing the folding mirror of the vibration suppression jig is variable.
[5] An image forming apparatus (image forming apparatus 200, FIG. 5) comprising the optical scanning device according to any one of [1] to [4].

According to the optical scanning device of the present invention, the vibration suppression jig presses a predetermined position in the longitudinal direction of the folding mirror supported and fixed at both ends, and the apparent rigidity in the short side direction and the thickness direction of the folding mirror is obtained. By improving, the natural frequency related to the bending vibration of the folding mirror is increased, and the amount of change in the beam spot position due to the mirror bending vibration is reduced, so that the output image quality can be improved.
Further, according to the image forming apparatus of the present invention, by using the optical scanning apparatus of the present invention, it is possible to reduce the beam spot position fluctuation due to the bending vibration of the folding mirror, and to obtain a higher quality image than before. it can.

It is a top view which shows the structure of the optical scanning device based on this invention. It is a perspective view which shows the member structure regarding installation of the folding | turning mirror in the optical scanning device of FIG. It is sectional drawing which shows the structural example of the vibration suppression jig and folding mirror used by this invention. It is sectional drawing which shows the structural example of the pressing member and screw used by this invention. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present invention.

The optical scanning device according to the present invention will be described below with reference to FIGS.
FIG. 1 is a top view showing a configuration of an optical scanning device according to the present invention.
In FIG. 1, 11 is an optical box, 12 is a light source unit that emits a laser beam, 13 is a cylinder lens that condenses the laser beam from the light source 12 in the sub-scanning direction, and 14 is a deflection scanning unit that deflects and scans the laser beam. 14a is a polygon mirror that reflects the laser beam, 14b is a drive motor that rotationally drives the polygon mirror 14a, 15a and 15b are scanning lenses such as an fθ lens and a surface tilt correction lens, and 16 is before irradiating the photosensitive drum. The light detection mirror 17 reflects the laser beam L2, the light detection unit 17 detects the laser beam L2 from the light detection mirror 16, and the reflection 101 irradiates the photosensitive drum by reflecting the laser beam L1 from the polygon mirror 14a. The mirror 104 is a predetermined portion in the longitudinal direction of the folding mirror 101 (for example, the longitudinal direction A central portion) of the presser folding mirror 101 apparent suppressing vibration suppression jig bending vibration to improve the rigidity of the (also referred to as a damper).

FIG. 2 is a perspective view showing a member configuration relating to the installation of the folding mirror of the optical scanning device of the present invention, and FIG. 3 is a cross-sectional view showing a configuration example of the vibration suppressing jig and the folding mirror in FIG.
Reference numerals 102a and 102b are provided integrally with the optical box 11, support both ends of the folding mirror 101 placed thereon, and bring the reflecting surface of the folding mirror 101 into contact with the inclined seating surface 102c, thereby turning the mirror 101. The seating members 103a and 103b for determining the inclination angle of the plate springs 105a and 103b are attached to the seating members 102a and 102b with screws, and a leaf spring 105 for applying a pressing force so that the folding mirror 101 is fixed to the seating members 102a and 102b. A pressing member that directly presses the folding mirror 101, 106 is a screw that applies a pressing force to the pressing member 105, and 107 is an attachment member that is detachably fixed to the bottom surface of the optical box 11 and that the pressing member 105 is attached via the screw 106. is there.

  Note that the vibration suppression jig 104 includes a pressing member 105, a screw 106, and an attachment member 107. The attachment member 107 is a Y-shaped component obtained by sheet-metal processing the same material as the optical box 11, and two of the three Y-shaped end portions are fixed to the bottom surface of the optical box 11 with screws, and the rest A presser member 105 is attached to one place via a screw 106. When the attachment member 107 is attached as a constituent member of the vibration suppressing jig 104, the attachment member 107 may be elastically deformed like a leaf spring so as to press the holding member 105 against the folding mirror 101, or it is not elastically deformed. A highly rigid member may be used.

  FIG. 4 is a cross-sectional view showing a more detailed configuration of the pressing member 105 and the screw 106 in FIG. The holding member 105 is a rectangular parallelepiped having higher rigidity than the folding mirror 101, and has a metal member 105a provided with a V-shaped groove portion on the surface in contact with the folding mirror 101, and a rigidity on the V-shaped groove surface of the metal member. It is composed of an elastic layer 105b in which an elastic body is provided in a thin layer so as to be negligible. When the vibration suppressing jig 104 is attached to the bottom surface of the optical box 11, the V-shaped groove of the holding member 105 comes into contact with the corner of the folding mirror 101, but the elastic layer 105 b contacts the folding mirror 101. It is possible to prevent the folding mirror 101 from being damaged.

  Reference numeral 108 denotes a dish-shaped disk attached to the tip of the screw 106. The screw 106 penetrates the through hole provided with the screw groove of the attachment member 107 in a state of being screwed with the screw groove, and protrudes downward (bottom side of the optical box 11), and the tip thereof is V of the metal member 105a. A disk 108 is provided at the tip of the screw 106 so as to be rotatable within the metal member 105a. As a result, the protruding amount of the disk 108 from the mounting member 107 can be adjusted by rotating the screw 106, and the holding member 105 turns the mirror 101 through the disk 108 toward the bottom surface of the optical box 11. The pressing force can be adjusted.

  Here, the folding mirror 101 is fixed to the seating surface members 102a and 102b by the leaf springs 103a and 103b with the inclination angle determined by the seating surface members 102a and 102b. Since the supporting force for suppressing the vibration is not given, as described above, the laser beam L1 reflected by the folding mirror 101 is greatly affected by the bending vibration when irradiated to the photosensitive drum (not shown). End up.

  Therefore, in the present invention, the vibration suppressing jig 104 is used to press the folding mirror 101 toward the bottom surface of the optical box 11 at a predetermined position in the longitudinal direction between the two seating surface members 102 a and 102 b of the folding mirror 101. .

  Detailed attachment procedures of the folding mirror 101 and the vibration suppression jig 104 are as follows (see FIGS. 2 and 3). That is, first, at both ends of the folding mirror 101, the reflecting surface of the folding mirror 101 is supported by contacting the inclined seating surfaces 102c of the two seating surface members 102a and 102b provided on the bottom surface of the optical box 11. Then, the inclination angle of the reflecting surface of the folding mirror 101 is determined, and then the leaf springs 103a and 103b are arranged so as to sandwich the both ends of the folding mirror 101 between the seating surface members 102a and 102b and screwed. Then, the spring elastic force of the leaf springs 103a and 103b acts to press the folding mirror 101 toward the seating surface members 102a and 102b, thereby fixing the folding mirror 101. Next, a vibration suppression jig 104 including a pressing member 105, a screw 106, and a mounting member 107 is arranged at a predetermined position in the longitudinal direction between the two seating surface members 102 a and 102 b of the folding mirror 101, and the V-shaped groove of the pressing member 105 is arranged. The fixing member 107 is fixed to the bottom surface of the optical box 11 by screwing the mounting member 107 to the corner of the folding mirror 101. Next, the protrusion amount of the disk 108 from the mounting member 107 is adjusted by rotating the screw 106 so that the pressing member 105 presses the folding mirror 101 toward the bottom surface of the optical box 11 with a predetermined force.

  As a result, the folding mirror 101 is supported by the seating surface members 102a and 102b at both ends thereof, and is pressed by a predetermined force toward the bottom surface of the optical box 11 at a predetermined position in the longitudinal direction. The apparent rigidity in the short direction and the thickness direction of 101 is improved, the natural frequency related to the bending vibration of the folding mirror 101 is increased (the bending vibration amplitude is reduced), and the photosensitive drum is irradiated in the optical scanning device. Sub-scanning beam spot position fluctuations due to mirror bending vibration of the laser beam can be suppressed. Therefore, it is possible to improve the output image quality in the image forming apparatus described later. Further, the vibration suppressing jig 104 has a function of suppressing the rotational moment of the folding mirror 101 in order to apply a pressing force to the folding mirror 101 from the diagonal direction with the seating surface members 102a and 102b.

  The arrangement position of the vibration suppressing jig 104 with respect to the folding mirror 101 is preferably the central portion in the longitudinal direction between the two seating surface members 102a and 102b, but the seating surface members 102a and 102b are arranged so that the folding mirror 101 does not resonate. The natural frequency (resonance frequency) of the folding mirror 101 may be adjusted as an arbitrary position in the longitudinal direction.

Next, the configuration of the image forming apparatus according to the present invention will be described.
FIG. 5 shows the configuration of the image forming apparatus according to the present invention, and is an overall side view of the image forming apparatus using the optical scanning device of the present invention.
In FIG. 5, an image forming apparatus 200 that is an electrophotographic apparatus arranges image forming units 110, 120, 130, and 140 for each color on an intermediate transfer belt 151, and forms a color image with toner on the intermediate transfer belt 151. The color image is transferred to a sheet 171 that is a recording medium conveyed from the sheet feeding device 170, and the fixing device 160 melts and fixes the toner with heat and pressure to form a color image.

  There are four types of image forming units 110, 120, 130, and 140, each having a K developing unit 110 having black toner, a C developing unit 120 having cyan toner, an M developing unit 130 having magenta toner, and a yellow toner. Y developing unit 140. For example, the image forming unit 110 includes a toner hopper for storing toner, a developing device 114 including a developing roller for forming a toner layer and bringing the toner into contact with the photosensitive drum 111, a drum cleaner 115 for cleaning the photosensitive drum 111, and a photosensitive member. A charger 112 for charging the drum 111 and an optical scanning device 113 for writing an electrostatic latent image on the photosensitive drum 111 are configured. The toner hopper, the developing roller, the drum cleaner 115, the charger 112 and the like included in the image forming unit 110 are attached to a frame (not shown in FIG. 5) and configured to be able to be pulled out from the main body of the image forming apparatus 200. Yes. As the optical scanning device 113, the optical scanning device of the present invention (FIG. 1) having the above-described vibration suppressing jig 104 is used.

  The intermediate transfer belt 151 is stretched around a plurality of rollers and is conveyed by the secondary transfer roller 150. The belt cleaner 152 removes residual toner on the intermediate transfer belt 151. The primary transfer roller is disposed so as to face the photosensitive drum 111 and the like, and is disposed inside the intermediate transfer belt 151 so as to face the photosensitive drum 111 and the like.

  The paper 171 is pulled out one by one by a pick roller from the paper feeding device 170 on which the paper is deposited, passes through a separation roller, and comes into contact with the intermediate transfer belt 151 while being pressed by the secondary transfer roller 150 and its opposing roller. The image is transferred and reaches the fixing device 160 via the conveyance belt.

  The fixing device 160 includes a backup roller 163, an elastic roller 162, a heating roller, a fixing belt 161, and the like. The fixing belt 161 is stretched between the elastic roller 162 and the heating roller, and is conveyed by the rotation of the heating roller or other rollers. The heating roller has heating means such as a halogen heater in a metal hollow shaft, and heats the fixing belt 161. The surface of the elastic roller 162 is formed of an elastic material such as silicon rubber, and the nip portion is protruded toward the elastic roller 162 by pressing the backup roller 163 to prevent the paper 171 from being wound around the fixing belt 161. When the sheet 171 passes through the fixing device 160, the sheet 171 is heated while being pressed with a predetermined pressure to the elastic roller 162 side by the backup roller 163 at the nip portion.

  When an image is formed, the surface of the photosensitive drum 111 is charged by the charging device 112 and light corresponding to the image is applied by the optical scanning device 113 to drop the potential on the photosensitive drum 111. The portion reaches the developing device 114 due to the rotation of the photosensitive drum 111, and when it comes into contact with the toner layer on the developing device 114, charged toner adheres to the image position.

  The toner image on the photosensitive drum 111 is transferred onto the intermediate transfer belt 151 at a portion where the primary transfer roller presses the intermediate transfer belt 151 toward the photosensitive drum 111. The toner images on the photosensitive drums 111 of the image forming units 110, 120, 130, and 140 are transferred onto the intermediate transfer belt 151 to form a color toner image. Then, the toner image is transferred onto the sheet 171 conveyed at the site of the secondary transfer roller 150 by the conveyance of the intermediate transfer belt 151. The sheet 171 having the toner image transferred thereon is conveyed to the fixing device 160 by a conveying belt, and the toner is melted and fixed by heat and pressure to form a color image.

  In the image forming apparatus 200 of the present invention, since the beam spot position fluctuation due to the bending vibration of the folding mirror 101 can be reduced in the optical scanning apparatus 113 of the present invention, a high-quality image with little color shift can be obtained.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

DESCRIPTION OF SYMBOLS 11 Optical box 12 Light source unit 13 Cylinder lens 14 Deflection scanning unit 14a Polygon mirror 14b Drive motor 15a, 15b Scanning lens 16 Photodetection mirror 17 Photodetection unit 101 Folding mirror 102a, 102b Seat surface member 102c Seat surface 103a, 103b Leaf spring 104 Vibration suppression jig 105 Holding member 106 Screw 107 Mounting member 108 Disk 110, 120, 130, 140 Image forming unit 111 Photoreceptor drum 112 Charger 113 Optical scanning device (latent image forming device)
114 Developing Device 115 Image Carrier Cleaner 150 Secondary Transfer Roller 151 Intermediate Transfer Belt 152 Belt Cleaner 160 Fixing Device 161 Fixing Belt 162 Elastic Roller 163 Backup Roller 170 Paper Feeding Device 171 Paper (Recording Medium)

JP 2002-182144 A JP 2000-227569 A

Claims (5)

A light source, a light deflector for scanning the light beam emitted from the light source, and a single or a plurality of long lengths for exposing and scanning the surface to be scanned with the light beam deflected and scanned by the light deflector An optical scanning device comprising the light source, the light deflector, and the folding mirror mounted in an optical box,
Both ends of the folding mirror are fixed in a state where the reflecting surface of the folding mirror is inclined and supported by two support members provided on the bottom surface of the optical box,
An optical scanning device comprising: a vibration suppressing jig for pressing the folding mirror toward the bottom surface of the optical box at a predetermined position in the longitudinal direction between the two support members of the folding mirror.   The optical scanning device according to claim 1, wherein the vibration suppression jig is detachably mounted in the optical box.   The optical scanning device according to claim 1, wherein the vibration suppression jig includes an elastic member in a contact portion with the folding mirror.   The optical scanning device according to claim 1, wherein a force for pressing the folding mirror of the vibration suppression jig is variable.   An image forming apparatus comprising the optical scanning device according to claim 1.

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