JP2008070774A - Light deflector, optical scanning device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light deflector the shaft collapse of which is made small by removing the inclination of a bearing-fixed part due to a warp of a base stock of a metal-based printed board or the residual deformation of the metal-based printed board after punched; and to provide a high-precision optical scanning device and an image forming apparatus. <P>SOLUTION: The light deflector is configured such that: a polygon mirror-fixed rotating body is supported by a bearing; the bearing is fixed to the metal-based printed board; and a mounting reference surface to a box unit is provided, wherein a plane for fixing the bearing, which is almost parallel to the mounting reference surface to be fit to a box unit and the base stock of which is made different from that of the printed board, is arranged on the printed board so that the bearing is fixed to the printed board in such a state that the fixed part of the bearing is abutted on the plane for fixing the bearing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical deflector, an optical scanning device, and an image forming apparatus that are used in a digital copying machine, a laser printer, and the like and deflect a light beam.

  Patent Document 1 discloses an optical scanning device that can easily adjust the influence of the axis tilt of the rotary polygon mirror at the mechanical accuracy level and cancel the axis tilt. That is, as shown in FIG. 2 of Patent Document 1, the semiconductor laser unit 5 has a cylindrical surface 13 having a curvature in the sub-scanning direction at a joint portion with the housing 6 such as the rotary polygon mirror 7. By the curvature of the cylindrical surface 13, the holding member 4 of the semiconductor laser unit 5 that holds the coupling lens 2 and the aperture 3 is tilted to a required angle within the plane including the sub-scanning direction of the emitted laser light L. Enable.

Patent Document 2 discloses a technique for improving the axis tilt accuracy of a rotary shaft with respect to a motor board and an optical box of a scanner motor using a dynamic pressure bearing. That is, the final tilting of the inner diameter of the bearing sleeve and the motor board mounting surface are machined with a single chuck, thereby improving the accuracy of the axis of the rotation shaft with respect to the motor board.
JP 7-318844 A JP 2003-295099 A

  However, the invention of Patent Document 1 requires a mechanism for adjusting the axis tilt of the rotary polygon mirror, and there is a problem that adjustment work is required. In addition, if the tilting accuracy is not obtained and the variation in tilting becomes large, the position where the light beam emitted from the polygon mirror passes through the scanning lens varies in the thickness direction, and the range in which the light beam is transmitted and used is limited. It becomes larger in the thickness direction. For this reason, there is a problem that the guaranteed range of optical characteristics is increased, the thickness of the scanning lens is increased, the yield of non-defective products is reduced, and the environmental load is increased.

  In the invention of Patent Document 2, the inner diameter of the bearing sleeve and the motor board mounting surface of the bearing sleeve can be formed with high precision, but the shaft collapse due to warpage of the motor board material or residual deformation after punching. There was a problem that could not be removed.

  The present invention has been made in view of the above circumstances, and eliminates the inclination of the bearing fixing portion caused by warpage of a metal-based printed circuit board material or residual deformation after punching, thereby reducing light deflection with a small axis collapse. An object of the present invention is to provide a high-precision optical scanning device and image forming apparatus.

  In order to achieve this object, the invention according to claim 1 is characterized in that a rotating body to which a polygon mirror is fixed is supported by a bearing, the bearing is fixed to a metal-based printed circuit board, and a reference for mounting the housing on the printed circuit board. In the optical deflector provided with the surface, the printed circuit board has a bearing fixing surface that is substantially parallel to the reference surface for mounting to the housing and is different from the material surface of the printed circuit board, and the bearing fixing surface has a bearing fixing portion. It is fixed in the contact state.

  According to a second aspect of the present invention, in the first aspect of the invention, the bearing fixing surface is formed by cutting a part of the printed circuit board.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the bearing fixing surface is formed by cutting or grinding.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the bearing fixing surface is formed by adding another material to the printed circuit board.

  The invention according to claim 5 is the invention according to claim 4, wherein the bearing fixing surface is formed by resin molding.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the reference mounting surface to the housing is formed by a surface different from the material surface of the printed circuit board, It was formed by the same method.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the fixing portion of the bearing is fixed to the printed circuit board by caulking.

  The invention according to claim 8 is the invention according to any one of claims 1 to 6, wherein the fixing portion of the bearing is fixed to the printed circuit board by adhesion.

  According to a ninth aspect of the present invention, a beam from a semiconductor laser is guided to a scanned surface through an optical system including an optical deflector to form a light spot and deflected by the optical deflector. In the optical scanning device that scans the scanning line, the optical deflector is the optical deflector according to any one of claims 1 to 8.

  According to the tenth aspect of the present invention, there are a plurality of beams from the semiconductor laser, which are guided to the scanning surface via an optical system including the optical deflector to form a plurality of light spots and deflected by the optical deflector. Accordingly, in the optical scanning device that performs adjacent scanning of a plurality of scanning lines on the surface to be scanned, the optical deflector is the optical deflector according to any one of claims 1 to 8.

  According to an eleventh aspect of the present invention, there is provided an image forming apparatus in which a latent image is formed on a photosensitive surface of a photosensitive medium by optical scanning using an optical scanning device, and the latent image is visualized to obtain an image. The optical scanning device according to claim 9 or 10 is used as the optical scanning device that performs the optical scanning.

  According to the present invention, it is possible to provide an optical deflector with a small axis collapse by eliminating the inclination of the bearing fixing portion due to the warp of the metal-based printed circuit board material or the residual deformation after punching, In addition, a highly accurate optical scanning device and image forming apparatus can be provided.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  A configuration of an optical deflector that is Embodiment 1 of the present invention will be described with reference to a sectional view of FIG. 1 and a perspective view of a rotating body of FIG.

  As shown in FIG. 1, the rotating body 101 of the optical deflector includes a bearing shaft 102, a mirror rotor 105, and a rotor magnet 106.

  The radial bearing is an oil-impregnated bearing including a bearing shaft 102 and a fixed sleeve 107, and the bearing clearance is set to 10 μm or less in diameter. In order to ensure the stability at high speed rotation, the radial bearing is provided with a dynamic pressure generating groove (not shown). The dynamic pressure groove is provided on the outer peripheral surface of the bearing shaft 102 or the inner peripheral surface of the fixed sleeve 107, but is preferably provided on the inner periphery of the fixed sleeve 107 made of a sintered member having good workability. The material of the bearing shaft 102 is preferably martensitic stainless steel (for example, SUS420J2) that can be quenched, can have high surface hardness, and has good wear resistance.

  The rotor magnet 106 is fixed to the lower inner surface of the mirror rotor 105, and constitutes an outer rotor type brushless motor together with a stator core 109 (winding coil 109 a) fixed to the bearing housing 108. The rotor magnet 106 is a bonded magnet using a resin as a binder, and the outer diameter portion of the rotor magnet 106 is held by the mirror rotor 105 so as not to be broken by centrifugal force during high-speed rotation. The rotor magnet 106 may be fixed by an adhesive. However, the rotor magnet 106 is made of a material having a linear expansion coefficient substantially equal to that of the mirror rotor 105, and is pressed and fixed to achieve higher rotation speed and a high temperature environment. In this case, it is possible to maintain a high accuracy in the balance of the rotating body without causing a slight movement of the fixed portion.

  The axial bearing is a pivot bearing in which the convex receiving surface 102a formed on the lower end surface of the bearing shaft 102 and the thrust receiving member 110 are brought into contact with the opposing surface. The thrust receiving member 110 uses a resin material or the like to improve the lubricity, or the surface of the martensitic stainless steel or ceramics or metal member is subjected to a hardening treatment such as a DLC (diamond-like carbon) treatment to produce wear powder. Occurrence is suppressed. The fixed sleeve 107 and the thrust receiving member 110 are housed in the bearing housing 108, and the fluid seal 111 prevents oil from flowing out.

  When rotating the rotating body 101 at a high speed of 25,000 rpm or higher, the balance of the rotating body 101 must be corrected and maintained with high accuracy in order to reduce vibration. The rotating body 101 has two upper and lower unbalance correction portions, and balance correction is performed by applying an adhesive or the like to the circumferential recesses 105 e and 105 f formed above and below the mirror rotor 105. The unbalance amount is required to be 10 mg · mm or less. For example, the correction amount is kept at 1 mg or less at a location having a radius of 10 mm. Note that when performing such minor corrections as described above, it is difficult to manage with an adherent such as an adhesive, or because the amount is small, the adhesive force is weak, and peeling off and scattering during high-speed rotation of 40,000 rpm or more. In that case, it is preferable to carry out a method (a cutting with a drill or a laser processing) for deleting a part of a part of the rotating body.

  The motor system in this embodiment is a system called an outer rotor type in which a magnetic gap is provided in the radial direction and the rotor magnet 106 is laid out on the outer diameter portion of the stator core 109. The rotation drive refers to the signal output from the Hall element 113 mounted on the printed circuit board 112 by the magnetic field of the rotor magnet 106 as a position signal, and rotates by switching the excitation of the winding coil 109a by the drive IC 114. The rotor magnet 106 is magnetized in the radial direction, and generates rotational torque with the outer periphery of the stator core 109 to rotate. The rotor magnet 106 has a magnetic path in the outer diameter direction open, and a Hall element 113 for switching excitation of the motor is disposed in the open magnetic path. Reference numeral 115 in FIG. 1 denotes a connector, to which a harness (not shown) is connected, and power is supplied from the main body, the motor is started and stopped, and control signals such as the rotational speed are input and output.

  On the upper part of the mirror rotor 105, two four-sided mirrors 105a and 105b are stacked in the rotation axis direction, and upper and lower deflection reflection surfaces 105d are formed with a 45 ° offset in the rotation direction. A cylindrical connecting portion 105c is formed between the polygon mirrors 105a and 105b. The polygon mirrors 105 a and 105 b, the connecting portion 105 c, and the holding portion 105 g of the rotor magnet 106 are formed as one integrated part and are shrink-fitted onto the bearing shaft 102. The part of the mirror rotor 105 that interferes with the upper end of the bearing housing 108 is cut into a cup shape.

  The mirror rotor 105 is made of a pure aluminum-based metal material, and secures a predetermined interval between the polygon mirrors 105a and 105b so that the deflection reflection surfaces 105d of the polygon mirrors 105a and 105b can be processed in an integrated state. A connecting portion 105c is provided.

  3 is a perspective view of the printed circuit board 112 shown in FIG. 1 as viewed from below, and FIG. 4 is an enlarged view of the main part of the rotating body 101 shown in FIGS. 1 and 2. Hereinafter, the present embodiment will be described in more detail with reference to FIGS.

  The printed circuit board 112 shown in FIG. 3 is formed of a metal-based printed circuit board such as steel or aluminum having a thickness of about 1 mm, and the material surface opposite to the surface on which the Hall element 113 and the drive IC 114 are mounted is used as it is. This is a reference surface 112b for attachment to an optical housing (not shown). The attachment to the optical housing (not shown) is fixed with screws using the attachment holes 112c. On the same side as the reference mounting surface 112b, the periphery of the center hole to which the bearing housing 108 is fixed is circular, and the material surface of the substrate is cut off by about 0.1 mm by cutting or grinding to form the bearing fixing surface 112a. ing. A cutting or grinding machine may be formed by turning using a lathe, or may be cut or ground using a milling machine or a grinding machine.

  The bearing housing 108 shown in FIG. 4 is firmly fixed to the printed circuit board 112 by plastic deformation of the caulking portion 108b in a state where the end surface 108a is in direct contact with the bearing fixing surface 112a of the printed circuit board 112. As in Example 2 described later, the bearing housing 108 and the printed circuit board 112 may be fixed using an adhesive.

  As described above, in the first embodiment, the metal-based printed circuit board and the bearing fixing portion are firmly fixed by a method (using caulking or using an adhesive) with a small axis collapse.

  Conventionally, the bearing housing 108 is tilted and fixed due to warpage of the printed circuit board material in the rolling roll direction or residual deformation after punching, and the shaft collapse sometimes increases.

  FIG. 5 shows a state of warping in order to explain a shaft collapse caused by warping of a conventional printed circuit board. As actual warpage and residual deformation, a slight deformation amount of about several μm to several tens of μm causes a shaft collapse. If the axis tilt is large, the position where the light beam passes through the scanning lens is shifted from a predetermined position, the image forming position of the light beam is shifted, and the beam shape is deteriorated, so that the axis tilt is about 0.1 ° or less. It is necessary to become.

  In the optical deflector according to the first embodiment, the printed board material around the center hole to which the bearing housing 108 is fixed is warped in the rolling direction, or residual deformation after punching is removed, so that it is parallel to the mounting reference surface 112b. The bearing fixing surface 112a is formed with high accuracy, and shaft tilt can be suppressed to 0.1 ° or less. In addition, the high-precision bearing fixing surface 112a can be easily formed at a low cost by cutting or grinding.

  As described above, according to the present embodiment, the optical deflector with a small axis collapse is obtained by eliminating the inclination of the bearing fixing portion caused by the warp of the material of the metal-based printed circuit board or the residual deformation after the punching process. Can be realized.

  Further, according to the present embodiment, the bearing fixing surface can be formed with high accuracy by scraping off the warpage of the metal-based printed circuit board material or the residual deformation after the punching process.

  Further, according to the present embodiment, it is possible to carry out warping of a metal-based printed circuit board material, removal of residual deformation after punching, and formation of a highly accurate bearing fixing surface at a low cost.

  In the first embodiment, when the bearing fixing surface 112a is formed by cutting or grinding, fixing to the processing machine in the same state as when fixing to the optical housing is suitable for reducing the shaft collapse.

  In the first embodiment, the two-stage optical deflector in which two four-sided mirrors 105a and 105b are stacked in the rotation axis direction has been described. However, a general one-stage optical deflector can also be applied. Of course.

  In FIG. 3 of the first embodiment, only the bearing fixing surface 112a is scraped off, and the material surface of the substrate is used as it is as the mounting reference surface 112b. However, in the second embodiment, the bearing fixing surface 112a is used as shown in FIG. In addition to this, an attachment reference surface 112b (shaded portion in the figure) to the optical housing is also formed by cutting or grinding. As a result, the bearing fixing surface 112a and the attachment reference surface 112b can be formed as parallel surfaces with higher accuracy, and shaft tilt can be reduced.

  As described above, according to the present embodiment, it is possible to realize an optical deflector with a smaller axial tilt than that of the first embodiment by reducing the inclination of the bearing fixing portion with respect to the reference mounting surface of the metal-based printed circuit board. .

  A configuration of an optical deflector that is Embodiment 3 of the present invention will be described with reference to a cross-sectional view of FIG. 7 and a perspective view of the printed circuit board of FIG. 8 viewed from below. Since the configuration of the printed circuit board in the third embodiment is different from that in the first embodiment, the same components in the third embodiment as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The printed circuit board 120 shown in FIG. 7 is made of a metal-based printed circuit board such as steel or aluminum having a thickness of about 1 mm, and mounting holes are formed on the material surface opposite to the surface on which the Hall element 113 and the driving IC 114 are mounted. As shown in FIG. 8, a reference mounting surface 120b and a bearing fixing surface 120a are formed by molding and adding resin by resin molding to the periphery and a part near the center hole where the bearing housing 108 is fixed. . Also, as shown in FIG. 8, the attachment to the optical housing (not shown) is fixed with screws using the attachment holes 120c.

  The bearing housing 108 is firmly fixed to the printed circuit board 120 with an adhesive in a state where the end surface 108 a is in direct contact with the bearing fixing surface 120 a of the printed circuit board 120. As in the first embodiment, the bearing housing 108 and the printed circuit board 120 may be fixed by caulking.

  In the optical deflector of the third embodiment, the reference mounting surface is obtained by correcting the warpage in the rolling roll direction of the printed circuit board material around the center hole to which the bearing housing 108 is fixed or the residual deformation after punching with an additional material. The bearing fixing surface 120a is formed with high accuracy in parallel with 120b, and the shaft collapse can be suppressed to 0.1 ° or less. Further, a highly accurate bearing fixing surface can be easily formed at a low cost by molding.

  As described above, according to the present embodiment, the optical deflector with a small axis collapse is obtained by eliminating the inclination of the bearing fixing portion caused by the warp of the material of the metal-based printed circuit board or the residual deformation after the punching process. Can be realized.

  Further, according to the present embodiment, the warpage of the metal-based printed circuit board material or the residual deformation after the punching process is corrected with the additional material, and the bearing fixing surface can be formed with high accuracy.

  Further, according to the present embodiment, it is possible to perform warpage of a metal-based printed board material, correction of residual deformation after punching, and formation of a bearing fixing surface at a low cost.

  In this embodiment, the mounting reference surface 120b to the optical housing is also formed by resin molding together with the bearing fixing surface 120a. Therefore, the bearing fixing surface 120a and the mounting reference surface 120b are formed as parallel surfaces with higher accuracy. It is possible to reduce the axis collapse.

  Therefore, according to the present embodiment, by reducing the inclination of the bearing fixing portion with respect to the mounting reference surface of the metal-based printed circuit board, an optical deflector with a smaller axial tilt than those of the first and second embodiments is provided.

  In the present embodiment, as in the first embodiment, only a part of the vicinity of the central hole to which the bearing housing 108 is fixed is subjected to resin molding, and the material surface of the substrate can be used as it is as the mounting reference surface 120b. . Further, the bearing fixing surface 120a and the mounting reference surface 120b may be formed by forming the material surface of the opposite substrate on which the mirror rotor 105 is disposed so as to be entirely covered with resin.

  Next, as Example 4, an optical scanning device using the optical deflectors of Examples 1 to 3 will be described with reference to FIG.

  In FIG. 9, reference numerals 1 and 1 ′ denote semiconductor lasers. The semiconductor lasers 1 and 1 ′ are “two light emitting sources constituting one light source”, and each emits one light beam. These semiconductor lasers 1, 1 ′ are held by the holder 2 in a predetermined positional relationship.

  The respective light beams emitted from the semiconductor lasers 1 and 1 ′ are converted by the coupling lenses 3 and 3 ′ into light beam forms (parallel light beams or weakly divergent or weakly convergent light beams) suitable for the subsequent optical system. The In this embodiment, the light beams coupled by the coupling lenses 3 and 3 ′ are both parallel light beams.

  Each light beam emitted from the coupling lenses 3 and 3 ′ and having a desired light beam shape is “beam-shaped” through the opening of the aperture 12 that regulates the light beam width, and then the half mirror prism 4. Is divided into two in the sub-scanning direction by the action of the half mirror prism, and each is divided into two light beams.

  This situation is shown in FIG. In order to avoid the complexity of the drawing, the light beam L1 emitted from the semiconductor laser 1 is shown as a representative. Although the vertical direction in FIG. 10 is the sub-scanning direction, the half mirror prism 4 has a semi-transparent mirror 4a and a reflecting surface 4b in parallel in the sub-scanning direction. When the light beam L1 is incident on the half mirror prism 4, the light beam L1 is incident on the semi-transparent mirror 4a, and part of the light beam L1 is transmitted straight through the semi-transparent mirror 4a to become the light beam L11, and the rest is reflected and incident on the reflecting surface 4b. The light beam L12 is totally reflected by 4b.

  In this embodiment, the semi-transparent mirror 4a and the reflecting surface 4b are parallel to each other, and thus the light beams L11 and L12 emitted from the half mirror prism 4 are parallel to each other. In this way, the light beam from the semiconductor laser 1 is divided into two light beams L11 and L12 in the sub-scanning direction. The light beam from the semiconductor laser 1 ′ is also divided into two in the same manner.

  In this way, two light beams are emitted from one light source (m = 1), and these two light beams are divided into two in the sub-scanning direction (q = 2) to obtain four light beams. It is done.

  Returning to FIG. 9, these four light beams enter the cylindrical lenses 5 a and 5 b and are condensed in the sub-scanning direction by the action of the cylindrical lenses 5 a and 5 b, and are deflected by the polygon mirror optical deflector 7. An image is formed in the vicinity of the reflecting surface as a “line image long in the main scanning direction”.

  As shown in FIG. 9, among the light beams emitted from the semiconductor lasers 1 and 1 ′ and divided by the half mirror prism 2, the light beam that has passed straight through the half mirror 4a of the half mirror prism 4 (see FIG. 10). A light beam L12) is incident on the cylindrical lens 5a, reflected by the semi-transparent mirror 4a, and further reflected by the reflecting surface 4b (light beam L12 shown in FIG. 10) is incident on the cylindrical lens 5b.

  In FIG. 9, reference numeral 6 indicates “soundproof glass” provided in a window of a soundproof housing of the polygon mirror type optical deflector 7. The four light beams from the light source side enter the polygonal mirror type light deflector 7 through the soundproof glass 6, and the deflected light beams are emitted to the scanning imaging optical system side through the soundproof glass 6.

  As shown in FIG. 9, the polygon mirror type optical deflector 7 has an upper polygon mirror 7a and a lower polygon mirror 7b that are stacked in two stages in the upper and lower directions in the direction of the rotation axis to be integrated, and around the rotation axis by a drive motor (not shown). It can be rotated to.

  In this embodiment, both the upper polygon mirror 7a and the lower polygon mirror 7b have the same shape having “four deflection reflection surfaces”. However, the lower polygon mirror 7b has the same shape as the deflection reflection surface of the upper polygon mirror 7a. The deflecting and reflecting surface is deviated by a predetermined angle: θ (= 45 degrees) in the rotation direction.

  In FIG. 9, reference numerals 8a and 8b denote "first scanning lenses", reference numerals 10a and 10b denote "second scanning lenses", and reference numerals 9a and 9b denote "optical path bending mirrors". Reference numerals 11a and 11b denote “photoconductive photoreceptors”.

  The first scanning lens 8a, the second scanning lens 10a, and the optical path bending mirror 9a are composed of two light beams (emitted from the semiconductor lasers 1 and 1 ') that are deflected by the upper polygon mirror 7a of the polygon mirror optical deflector 7. The two light beams transmitted through the semi-transparent mirror 4a of the half mirror prism 4) are guided to the photoconductive photoreceptor 11a which is the corresponding optical scanning position and separated in the sub-scanning direction. A set of scanning imaging optical systems for forming spots is formed.

  The first scanning lens 8b, the second scanning lens 10b, and the optical path bending mirror 9b are two light beams (emitted from the semiconductor lasers 1, 1 ′) deflected by the lower polygon mirror 7b of the polygon mirror optical deflector 7. The two light beams reflected by the half mirror 4a of the half mirror prism 4 are guided onto the photoconductive photoreceptor 11b which is the corresponding light scanning position, and separated in the sub scanning direction. A set of scanning imaging optical systems for forming a light spot is constructed.

  The optical arrangement of the light beams emitted from the semiconductor lasers 1, 1 ′ is determined so that “the principal rays intersect in the vicinity of the position of the deflecting reflecting surface” when viewed from the rotational axis direction of the polygon mirror optical deflector 7. Therefore, each pair of two light beams incident on the deflecting reflection surface has a mutual opening angle (when the light source side is viewed from the side of the deflecting reflection surface, it is orthogonal to the rotation axes of the two light beams. The angle formed by projection onto the surface).

  Due to this “open angle”, the two light spots formed on each of the photoconductive photoreceptors 11a and 11b are also separated in the main scanning direction, and thus two light beams for optically scanning each photoreceptor. Can be detected individually to synchronize the start of optical scanning for each light beam.

  In this way, the photoconductive photosensitive member 11a is subjected to multi-beam scanning with two light beams by the two light beams deflected by the upper polygon mirror 7a of the polygon mirror optical deflector 7, and the polygon mirror optical deflector. The photoconductive photosensitive member 11b is subjected to multi-beam scanning with two light beams by the two light beams deflected by the lower polygon mirror 7b.

  Since the deflecting and reflecting surfaces of the polygon mirror 7b, which is the upper polygon mirror 7a of the polygon mirror type optical deflector 7, are deviated from each other by 45 degrees in the rotational direction, the deflected light beam from the upper polygon mirror 7a is emitted from the photoconductive photoreceptor 11a. When scanning, the deflected light beam from the lower polygon mirror 7b is not guided to the photoconductive photoreceptor 11b, and when the deflected light beam from the lower polygon mirror 7b performs optical scanning of the photoconductive photoreceptor 11b, The light beam deflected by the upper polygon mirror 7a is not guided to the photoconductive photoreceptor 11a.

  That is, the optical scanning of the photoconductive photoreceptors 11a and 11b is performed "alternatingly shifted in time". FIG. 11 is a diagram for explaining this situation. Since FIG. 11 is an explanatory diagram, in order to avoid complications, the light beams (actually four beams) incident on the polygon mirror type optical deflector 7 are “incident light”, and the deflected light beams are “deflected light”. a, deflected light b ".

  FIG. 11A shows the situation when incident light enters the polygon mirror optical deflector 7 and the “deflected light a” deflected by being reflected by the upper polygon mirror 7a is guided to the optical scanning position. Show. At this time, the deflected light b from the lower polygon mirror 7b does not go to the optical scanning position. FIG. 11B shows a situation when “deflected light b” reflected and deflected by the lower polygon mirror 7 b is guided to the optical scanning position. At this time, the deflected light a from the upper polygon mirror 7a does not go to the optical scanning position.

  It should be noted that an appropriate light shielding means SD as shown in FIG. 11 is used so that the deflected light from the other polygon mirror does not act as “ghost light” while the deflected light from one polygon mirror is guided to the optical scanning position. It is preferable to shield the deflected light that is not guided to the optical scanning position by using. In practice, this can be easily realized by making the inner wall of the “soundproof housing” non-reflective.

  As described above, in the fourth embodiment shown in FIG. 9, since the optical scanning of the photoconductive photoreceptors 11a and 11b (multi-beam method) is performed alternately, for example, the optical scanning of the photoconductive photoreceptor 11a. Is performed, the light intensity of the light source is modulated by the “black image signal”, and when the photoconductive photoconductor 11b is scanned, the light intensity of the light source is modulated by the “magenta image signal”. For example, an electrostatic latent image of a black image can be written on the photoconductive photoreceptor 11a, and an electrostatic latent image of a magenta image can be written on the photoconductive photoreceptor 11b.

  FIG. 12 shows a time chart of “when all the light is lit in the effective scanning region” when writing the black image and the magenta image by the “common light source (semiconductor lasers 1 and 1 ′ in FIG. 9)”. . A solid line indicates a portion corresponding to writing of a black image, and a broken line indicates a portion corresponding to writing of a magenta image. As described above, the timing of writing out the black image and the magenta / magenta image is to the optical scanning start position by the synchronous light receiving means (not shown in FIG. 9, usually a photodiode) arranged outside the effective scanning area. It is determined by detecting the light beam going.

  In the optical scanning device according to the fourth embodiment, the optical deflectors according to the first to third embodiments are used as the polygon mirror optical deflector 7.

  As described above, according to the present embodiment, the axial tilt of the optical deflector is reduced, the variation in the position where the light beam passes through the scanning lens is suppressed, and the guaranteed range of the optical characteristics of the scanning lens is minimized. A multi-beam optical scanning device having a necessary range can be realized. As a result, the thickness of the scanning lens can be reduced, the yield of non-defective products can be increased, and the environmental load can be reduced. Further, there is no need to provide a special mechanism for correcting the axis collapse. Furthermore, the number of parts and materials of the light source unit are reduced, the environmental load is reduced, and the failure probability of the light source can be kept low.

  Next, an optical scanning apparatus and an image forming apparatus will be described as Embodiment 5 of the present invention with reference to FIGS.

  FIG. 13 shows a state in which the optical system portion of the optical scanning device is viewed from the sub-scanning direction, that is, from the rotational axis direction of the polygon mirror type optical deflector 7. In FIG. 13, for the sake of simplicity of illustration, the illustration of the mirror for bending the optical path on the optical path from the polygon mirror type optical deflector 7 to the optical scanning position is omitted, and the optical path is drawn in a straight line.

  In this optical scanning device, m = q = 2, p = 1, and n = 4 (m: number of light sources, q: number of divisions, p: number of light beams, n: optical scanning device), four light beams Each scanning position is optically scanned with one light beam. In addition, photoconductive photoconductors 11Y, 11M, 11C, and 11K are individually arranged at the optical scanning positions, and the electrostatic latent images formed on these four photoconductive photoconductors are magenta (M), yellow. Visualization is individually performed with toners of (Y), cyan (C), and black (CK) to form a color image.

  In FIG. 13, reference numerals 1YM and 1CK denote semiconductor lasers, respectively. Each of these semiconductor lasers 1YM and 1CK emits one light beam. The intensity of the semiconductor laser 1YM is alternately modulated with “an image signal corresponding to a yellow image” and “an image signal corresponding to a magenta image”. The intensity of the semiconductor laser 1CK is alternately modulated with “an image signal corresponding to a cyan image” and “an image signal corresponding to a black image”.

  The light beam emitted from the semiconductor laser 1YM is converted into a parallel beam by the coupling lens 3YM, and after passing through the aperture 12YM, the beam is shaped, and then incident on the half mirror prism 4YM and separated in the sub-scanning direction. Beam split into light beams. The half mirror prism 4YM is the same as the half mirror prism 4 described with reference to FIG. One of the split light beams is used to write a yellow image and the other one is used to write a magenta image.

  The two light beams divided in the sub-scanning direction are condensed in the sub-scanning direction by cylindrical lenses 5Y and 5M (arranged so as to overlap in the sub-scanning direction) arranged in the sub-scanning direction. The light enters the polygon mirror type optical deflector 7. The polygon mirror type optical deflector 7 is the same as that described with reference to FIGS. 9 and 11, and polygon mirrors having four deflection reflecting surfaces are stacked in two stages in the direction of the rotation axis. The deflecting and reflecting surfaces of the polygon mirrors are integrated by shifting in the rotational direction. A line image long in the main scanning direction by the cylindrical lenses 5Y and 5M is formed in the vicinity of the position of the deflection reflection surface of each polygon.

  The light beams deflected by the polygon mirror optical deflector 7 are transmitted through the first scanning lenses 8Y and 8M and the second scanning lenses 10Y and 10M, respectively, and light spots are formed at the optical scanning positions 11Y and 11M by the action of these lenses. Then, these optical scanning positions are optically scanned.

  Similarly, the light beam radiated from the semiconductor laser 1CK is converted into a parallel beam by the coupling lens 3CK, shaped through the aperture 12CK, and then separated into two in the sub-scanning direction by the half mirror prism 4CK. Beam split into light beams. The half mirror prism 4CK is the same as the half mirror prism 4YM. One of the split light beams is used to write a cyan image and the other one is used to write a black image.

  The two light beams divided in the sub-scanning direction are condensed in the sub-scanning direction by the cylindrical lenses 5C and 5K (arranged so as to overlap in the sub-scanning direction) arranged in the sub-scanning direction. Are incident on the polygon mirror type optical deflector 7 and deflected through the first scanning lenses 8C and 8K and the second scanning lenses 10C and 10K, respectively, and a light spot is formed at the optical scanning positions 11C and 11K by the action of these lenses. Then, these optical scanning positions are optically scanned.

  In FIG. 14, a portion denoted by reference numeral 20 is an optical scanning device, which is the portion described with reference to FIG. 13. As shown in FIG. 14, one of the light beams deflected by the upper polygon mirror of the polygon mirror optical deflector 7 has the optical scanning position determined by the optical path bent by the optical path folding mirrors mM1, mM2, and mM3. The other light beam is guided to the photoconductive photoconductor 11C that forms the substance of the optical scanning position by the optical path bent by the optical path bending mirrors mC1, mC2, and mC3. .

  In addition, one of the light beams deflected by the lower polygon mirror of the polygon mirror type optical deflector 7 is guided to the photoconductive photoreceptor 11Y which forms the substance of the optical scanning position by the optical path bent by the optical path folding mirror mY. The other light beam is guided to the photoconductive photosensitive member 11K that forms the substance of the optical scanning position by the optical path bent by the optical path bending mirror mK.

  Accordingly, the light beams from the m = 2 semiconductor lasers 1YM and 1CK are divided into two light beams by the half mirror prisms 4YM and 4CK, respectively, so that four light beams are obtained. The photoconductive photoreceptors 11Y, 11M, 11C, and 11K are optically scanned. The photoconductive photoreceptors 11Y and 11M are alternately scanned by the light beams obtained by dividing the light beam from the semiconductor laser 1YM into two as the polygon mirror optical deflector 7 rotates, and the photoconductive photoreceptors 11C and 11M With 11K, each light beam obtained by dividing the light beam from the semiconductor laser 1CK into two is alternately scanned with the rotation of the polygon mirror optical deflector 7.

  Each of the photoconductive photoconductors 11Y to 11K is rotated clockwise at a constant speed, and is uniformly charged by charging rollers TY, TM, TC, and TK that form a charging unit, and each receives light scanning of a corresponding light beam to yellow, Magenta, cyan, and black color images are written and corresponding electrostatic latent images (negative latent images) are formed.

  These electrostatic latent images are reversal developed by developing devices GY, GM, GC, and GK, respectively, and a yellow toner image, a magenta toner image, a cyan toner image, and a black toner are respectively formed on the photoconductive photoreceptors 11Y, 11M, 11C, and 11K. An image is formed.

  These color toner images are transferred onto a “transfer sheet” (not shown). That is, the transfer sheet is transported by the transport belt 17, the yellow toner image is transferred from the photoconductive photoreceptor 11Y by the transfer device 15Y, and the photoconductive photoreceptors 11M, 11C, and 15K are respectively transferred by the transfer devices 15M, 15C, and 15K. From 11k, a magenta toner image, a cyan toner image, and a black toner image are sequentially transferred.

  In this way, a yellow toner image to a black toner image are superimposed on the transfer sheet to compose a color image synthetically. This color image is fixed on the transfer sheet by the fixing device 19 to obtain a color image.

  That is, the embodiment shown in FIGS. 13 and 14 is obtained by individually forming an electrostatic latent image on a plurality of photoconductive photoreceptors by optical scanning, and visualizing these electrostatic latent images to obtain a toner image. In a tandem type image forming apparatus that transfers a toner image onto the same sheet-like recording medium to form a synthetic image, the number of photoconductive photoconductors is 4, and two light sources are used as an optical scanning device. A light beam from each light source is configured to optically scan two photoconductive photoreceptors using 1YM and 1CK, and is formed on four photoconductive photoreceptors 11M, 11Y, 11C, and 11K. The electrostatic latent image is visualized individually with magenta, yellow, cyan, and black toners to form a color image.

  In the optical scanning device provided in the image forming apparatus according to the fifth embodiment, the optical deflectors according to the first to third embodiments are used as the polygon mirror optical deflector 7.

  As described above, according to the present embodiment, the axial tilt of the optical deflector is reduced, the variation in the position where the light beam passes through the scanning lens is suppressed, and the guaranteed range of the optical characteristics of the scanning lens is minimized. A single beam optical scanning device having a required range can be realized. As a result, the thickness of the scanning lens can be reduced, the yield of non-defective products can be increased, and the environmental load can be reduced. Further, there is no need to provide a special mechanism for correcting the axis collapse. Furthermore, the number of parts and materials of the light source unit are reduced, the environmental load is reduced, and the failure probability of the light source can be kept low.

  Further, according to the present embodiment, it is possible to realize an image forming apparatus in which the image formation of the optical scanning device is highly accurate and the environmental load is reduced, and the image quality is high and the environmental load is small.

  In the image forming apparatus according to the fifth embodiment, each photoconductive photoconductor is scanned by the “single beam method”. However, each light source is configured as shown in FIG. Naturally, the light scanning of the body can be carried out by the “multi-beam method”.

  As mentioned above, although each Example of this invention was described, it is not limited to description of the said Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

  As described above, according to the present invention, an optical deflector with a small axis tilt can be obtained by eliminating the inclination of the bearing fixing portion caused by warpage of the material of the metal-based printed circuit board or residual deformation after punching. Can be provided.

  Further, according to the optical deflector of the present invention, it is possible to form the bearing fixing surface with high accuracy by scraping off the warp of the metal-based printed circuit board material or the residual deformation after punching.

  In addition, according to the optical deflector of the present invention, it is possible to carry out warping of a metal-based printed board material, elimination of residual deformation after punching, and formation of a highly accurate bearing fixing surface at a low cost.

  Further, according to the optical deflector of the present invention, it is possible to correct the warp of the metal-based printed circuit board material or the residual deformation after the punching with an additional material, and to form the bearing fixing surface with high accuracy.

  In addition, according to the optical deflector of the present invention, it is possible to perform warping of a metal-based printed board material, correction of residual deformation after punching, and formation of a bearing fixing surface at a low cost.

  In addition, according to the optical deflector of the present invention, it is possible to provide the optical deflector according to claim 1 in which the tilt of the bearing fixing portion with respect to the mounting reference surface of the metal-based printed circuit board is reduced, thereby further reducing the shaft tilt. it can.

  In addition, according to the optical deflector of the present invention, the metal-based printed circuit board and the bearing fixing portion can be firmly fixed by a method with little shaft collapse.

  According to the present invention, an optical scanning device that reduces the axial tilt of the optical deflector, suppresses variation in the position where the light beam passes through the scanning lens, and minimizes the guaranteed range of optical characteristics of the scanning lens. Can be provided. In addition, it is possible to provide an optical scanning device in which the thickness of the scanning lens is reduced, the yield of non-defective products is increased, and the environmental load is reduced. Furthermore, it is possible to provide a high-precision optical scanning device (single beam, multi-beam) without providing a special mechanism for correcting the axis tilt.

  According to the present invention, it is possible to provide an image forming apparatus in which the image formation of the optical scanning device is highly accurate and the environmental load is reduced, and the image quality is high and the environmental load is small.

It is a sectional side view which shows the whole structure of the optical deflector which is Example 1 of this invention. It is a perspective view which shows the external appearance of the rotary body of the optical deflector which is Example 1 of this invention. It is a perspective view which shows the downward appearance of the printed circuit board of the optical deflector which is Example 1 of this invention. It is a sectional side view which expands and shows the structure of the principal part of the optical deflector which is Example 1 of this invention. It is a sectional side view which shows the state of the axis fall resulting from the curvature of a printed circuit board concerning the optical deflector of a prior art. It is a perspective view which shows the downward appearance of the printed circuit board of the optical deflector which is Example 2 of this invention. It is a sectional side view which shows the whole structure of the optical deflector which is Example 3 of this invention. It is a perspective view which shows the downward appearance of the printed circuit board of the optical deflector which is Example 3 of this invention. It is a perspective view which shows the whole structure of the optical scanning device which is Example 4 of this invention. It is a figure which shows the state by which the light beam in the optical scanning device which is Example 4 of this invention was divided into two. It is a figure which shows the scanning state of the light beam in the optical scanning apparatus which is Example 4 of this invention. It is a time chart which shows the scanning timing of the light beam in the optical scanning device which is Example 4 of this invention. It is a figure which shows the state which looked at the optical system part of the optical scanning device which is Example 5 of this invention from the subscanning direction. It is a figure which shows the structure of the image forming apparatus which is Example 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 ', 1CK, 1YM Semiconductor laser 2 Holder 3, 3', 3CK, 3YM Coupling lens 4, 4CK, 4YM Half mirror prism 4a Semi-transparent mirror 4b Reflective surface 5a, 5b, 5CK, 5YM Cylindrical lens 6 Soundproof glass 7 Polyhedral mirror type optical deflector 7a Upper polygon mirror 7b Lower polygon mirror 8a, 8b, 8C, 8M, 8Y, 8K First scanning lens 9a, 9b, mC1, mC2, mC3, mM1, mM2, mM3, mY1, mY2, mY3 , MK1, mK2, mK3 Optical path bending mirrors 10a, 10b, 10C, 10M, 10Y, 10K Second scanning lenses 11a, 11b, 11C, 11M, 11Y, 11K Photoconductive photoreceptors 12, 12CK, 12YM Apertures 15C, 15M, 15Y, 15K Transfer device GC, GM, GY, GK Developing device TC, TM, TY, TK Charging roller 17 Conveying belt 20 Optical scanning device 101 Rotating body 102 Bearing shaft 102a Convex surface 105 Mirror rotor 105a, 105b Polyhedral mirror 105c Cylindrical connecting part 105d Vertical deflection reflecting surface 105e, 105f Circle Circumferential recess 105g Rotor magnet holding portion 106 Rotor magnet 107 Fixed sleeve 108 Bearing housing 108a End surface 108b Caulking portion 109 Stator core 109a Winding coil 110 Thrust receiving member 111 Fluid seal 112, 120 Printed circuit board 112a, 120a Bearing fixing surface 112b, 120b Mounting reference Surface 112c, 120c Mounting hole 113 Hall element 114 Drive IC
115 Connector L1, L11, L12 Light beam SD Light blocking means

Claims (11)

In an optical deflector in which a rotating body to which a polygon mirror is fixed is supported by a bearing, the bearing is fixed to a metal-based printed circuit board, and a mounting reference surface to the housing is provided on the printed circuit board.
The printed circuit board is substantially parallel to a reference surface for attachment to the housing, and includes a bearing fixing surface different from the material surface of the printed circuit board,
An optical deflector fixed in a state where a fixed portion of the bearing is in contact with the bearing fixing surface.   The optical deflector according to claim 1, wherein the bearing fixing surface is formed by cutting a part of the printed board.   The optical deflector according to claim 1, wherein the bearing fixing surface is formed by cutting or grinding.   4. The optical deflector according to claim 1, wherein the bearing fixing surface is formed by adding another material to the printed circuit board. 5.   The optical deflector according to claim 4, wherein the bearing fixing surface is formed by resin molding.   The mounting reference surface to the casing is formed by a surface different from a material surface of the printed circuit board, and is formed by the same method as the bearing fixing surface. An optical deflector as described in 1.   The optical deflector according to claim 1, wherein the fixed portion of the bearing is fixed to the printed circuit board by caulking.   The optical deflector according to claim 1, wherein the fixed portion of the bearing is fixed to the printed circuit board by adhesion. A beam from the semiconductor laser is guided to the surface to be scanned through an optical system including an optical deflector to form a light spot and deflected by the optical deflector, thereby scanning the scanning surface with the scanning line. In an optical scanning device,
The optical scanning device according to claim 1, wherein the optical deflector is the optical deflector according to claim 1. A plurality of beams from the semiconductor laser are guided to the scanned surface via an optical system including an optical deflector to form a plurality of light spots and deflected by the optical deflector. In an optical scanning device that performs adjacent scanning of a plurality of scanning lines,
9. The optical scanning device, wherein the optical deflector is the optical deflector according to claim 1. An image forming apparatus for forming a latent image by performing optical scanning on a photosensitive surface of a photosensitive medium by an optical scanning device and visualizing the latent image to obtain an image,
An image forming apparatus using the optical scanning device according to claim 9 or 10 as an optical scanning device for optically scanning a photosensitive surface of the photosensitive medium.

Images