JP2006221001A - Deflection scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deflection scanner in which balance correction efficiency is excellent and deterioration of surface accuracy of the reflection face of a rotating polygon mirror is reduced. <P>SOLUTION: The deflection scanner in which a plurality of beams are separated in a rotating shaft direction and made incident on the reflection face of the rotating polygon mirror has: the rotating polygon mirror on which the reflection face of the rotating polygon mirror is separated into a plurality of parts in the rotation axis direction according to the incident position; a motor which rotationally drives the rotating polygon mirror; a bearing means which rotationally supports a rotating member which is integrated with the rotating polygon mirror; and a rotating body including the rotating polygon mirror, the rotating part of the motor, and the rotating member. Non-reflection faces between the separated reflection faces of the rotating polygon mirror is used as balance correction parts of a rotating body. The balance of one face of the rotating body can be corrected only by the balance correction part of the non-reflection faces between the separated reflection faces. Further, the non-reflection faces between the separated reflection faces can form a radius larger than the radius of the inscribed circle of the reflection faces. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a deflection scanning apparatus that is used in a laser beam printer or the like and deflects and scans a plurality of laser beams.

  A deflection scanning apparatus used in an electrophotographic image forming apparatus such as a laser beam printer or a laser facsimile deflects and scans a light beam such as a laser beam by a rotating polygon mirror that rotates at high speed, and the obtained scanning light is rotated by a rotating drum. An electrostatic latent image is formed by forming an image on the upper photoconductor. Next, the electrostatic latent image on the photosensitive member is visualized as a toner image by a developing device, transferred to a recording medium such as recording paper, sent to a fixing device, and the toner on the recording medium is heated and fixed for printing ( Print).

  FIG. 4 shows a main part of a deflection scanning apparatus according to a conventional example, which is a deflection scanning apparatus described in Patent Document 1. The external appearance of the hydrodynamic air bearing type deflection scanning device 130 is formed by a housing 131 and an upper cover 132 fixed on the housing 131, and a fixed shaft 133 is press-fitted to the center of the bottom of the housing 131 or is fit-fitted. It is fixed by the method.

  The fixed shaft 133 has a herringbone groove 133a formed at an appropriate position on the peripheral wall portion thereof, and a ring-shaped permanent magnet assembly 134 having a predetermined length in the axial direction is formed in the upper end recess of the fixed shaft 133. Is buried.

  The permanent magnet assembly 134 includes a ring-shaped permanent magnet 135 in which a center circle of a predetermined size is formed at the center thereof, is magnetized in two poles in the axial direction, and the magnetic poles are oriented in the axial direction. A pair of fixed yoke plates 136 made of a ferromagnetic material and having a center circle fixed at both ends in the axial direction (both ends in the axial direction) and smaller than the center circle (inner diameter) of the permanent magnet 135. Yes. The permanent magnet assembly 134 is embedded in the recessed portion at the upper end of the fixed shaft 133 with the permanent magnet 135 sandwiched between the pair of fixed yoke plates 136.

  The upper part of the fixed shaft 133 is inserted into the hollow of the cylindrical rotating sleeve 137. The fixing shaft 133 is formed in a cap shape from the upper surface to the outer peripheral surface of the rotating sleeve 137, and has an outward (radial) direction. A flange (holding member) 138 protruding in a shape is fixed. A magnetic bearing rotating part 139 is press-fitted and fixed to the flange 138 at the center part of the flange 138, and the magnetic bearing rotating part 139 forms a magnetic gap between the central circle parts of the pair of fixed yoke plates 136. An outer cylinder surface is formed.

  A rotating polygon mirror 140 is placed on the upper surface of the seat surface 138 a protruding in a flange shape of the flange 138, and the rotating polygon mirror 140 is pressed against the flange 138 of the rotating sleeve 137 by the rotating polygon mirror holding spring 141. At the same time, the rotary polygon mirror presser spring 141 is fixed to the magnetic bearing rotating portion 139 by screwing the screw 142 into a screw hole formed in the upper end portion of the magnetic bearing rotating portion 139 and fixing it to the magnetic bearing rotating portion 139. Has been.

  As described above, the flange 138 is attached to the rotary sleeve 137 in a state where the hollow portion above the rotary sleeve 137 is closed, and the hollow of the rotary sleeve 137 closed by the upper end of the fixed shaft 133 and the flange 138 is attached. An air reservoir 143 is formed in the part.

  The magnetic bearing rotating part 139 is formed of a material with high dimensional accuracy, such as a permanent magnet or a steel-based ferromagnetic material. The fixed shaft 133, the rotary sleeve 137, and the rotary polygon mirror presser spring 141 are made of a non-magnetic material, and a magnetic flux leaks into the gap between the permanent magnet assembly 134 that generates an attractive force and the magnetic bearing rotary part 139. Is suppressed, and an axial suction force is efficiently generated in an axial bearing described later.

  In addition, a fine hole 138 a is formed around the magnetic bearing rotating portion 139 in the flange 138 so that the air reservoir 143 communicates with the outside of the rotating sleeve 137 through a slit (not shown) of the rotary polygon mirror holding spring 141. The fine hole 138a has an appropriate damping characteristic for an axial bearing described later, due to the viscous resistance of the air passing through the fine hole 138a.

  A rotor magnet 144 is attached circumferentially on the lower surface of the flange 138 and in the outer circumferential direction of the rotary sleeve 137.

  The rotating sleeve 137 to which the flange 138, the magnetic bearing rotating portion 139, the rotating polygon mirror 140, the rotating polygon mirror holding spring 141, the screw 142, the rotor magnet 144, and the like are attached constitutes a rotating body 145.

  A stator core 146 is disposed on the inner peripheral side facing the rotor magnet 144, and a winding coil 146 a is wound around the stator core 146. A substrate 147 and a hall element 148 are disposed below the stator core 146 around which the rotor magnet 44 and the winding coil 146a are wound. The substrate 147 and the stator core 146 around which the winding coil 146 a is wound are attached to the housing 131, and the Hall element 148 is attached to the substrate 147.

  A drive circuit (not shown) is formed on the substrate 147. The rotor magnet 144, the stator core 146, the winding coil 146a, the substrate 147, the Hall element 148, and the like constitute a radial gap / outer rotor type brushless motor 149. The brushless motor 149 rotates the rotating body 145 by switching the excitation by controlling the energization to the winding coil 148 sequentially based on the position detection signal of the Hall element 148 by the drive circuit of the substrate 147. And control at a constant speed.

  Further, a balance correcting groove 138b for correcting the unbalance of the rotating body 145 is formed at the lower end of the flange 138, and the circumferential bent portion of the rotary polygon mirror presser spring 141 is used for correcting the unbalance. A balance correction unit 141a is formed.

  The rotary polygon mirror 140 has reflection surfaces 140a and 140b formed at the upper and lower ends in the axial direction, and a non-reflection surface 140c formed at the center in the axial direction. The reflecting surfaces 140a and 140b of the rotary polygon mirror 140 have an area sufficient to deflect a plurality of incident laser beams, that is, a length in the axial direction, and the non-reflecting surface 140c is a reflecting surface 140a. , 140b. The non-reflecting surface 140c may have a radius smaller than the inscribed circle radius of the reflecting surfaces 140a and 140b, but in practice, it is appropriately selected depending on the rigidity of the rotary polygon mirror 140 during processing. That is, if the non-reflective surface 140c is formed with a very small diameter, the mechanical rigidity of the material of the rotary polygon mirror 140 is lowered, and distortion may occur when the reflective surfaces 140a and 140b are processed.

  The length of the non-reflecting surface 140c in the axial direction is determined by the interval between the incident laser beams. The interval between the laser beams is a lens through which the laser beam passes after being deflected by the rotating polygon mirror 140. Determined by the interval.

  FIG. 5 shows a main part of another conventional deflection scanning apparatus, which is a deflection scanning apparatus described in Patent Document 2. It is a longitudinal cross-sectional view which shows the Example of the rotary polygon mirror used for a color image forming apparatus etc. A plurality of laser beams A, B, C, and D corresponding to the respective colors are incident on the four surfaces facing each other on the rotating polygon mirror reflecting surfaces 108a and 108b spaced apart in the axial direction of the rotating polygon mirror 101, so A deflection scan is performed.

  In the rotating polygon mirror 101, the upper outer periphery of the rotating shaft 110 made of martensitic stainless steel is fitted and fixed to a rotating member 108 having an aluminum purity of 99.9% or more having rotating polygon mirror reflecting surfaces 108a and 108b. . Martensitic stainless steel is suitable because it can be hardened and has high surface hardness, and has good wear resistance as a rotating shaft. A rotor magnet 111 is fixed to the lower inner surface of the rotating member 108, and constitutes an outer rotor type brushless motor together with the stator core 104a (winding coil 104).

  The rotating polygon mirror reflecting surfaces 108a and 108b have an area sufficient for deflecting a predetermined laser beam, and the space portion 108j separating the rotating polygon mirror reflecting surfaces 108a and 108b is included in the reflecting surfaces 108a and 108b. The shape is smaller than the diameter of the contact circle. By reducing the diameter of the space portion 108j, it is possible to effectively reduce the windage loss that increases as the rotation increases. The distance L between the upper and lower laser beams is determined by the vertical distance of the fθ lens that passes after deflection by the rotary polygon mirror reflecting surfaces 108a and 108b. The narrower the gap, the smaller the surface area and the smaller the overall windage loss.

  This structure has an advantage that there is no need to use a fixing member such as a leaf spring for the rotating polygon mirror, and hence there is no distortion on the reflecting surface of the rotating polygon mirror due to the fixing pressure. Circumferential grooves 108i and 108k provided on the rotary member 108 prevent stress strain on the rotary polygonal mirror reflecting surfaces 108a and 108b due to environmental shrinkage and fix adhesion when the rotary shaft 10 is fixed by shrinkage fitting. It is also used for the agent application part. The rotor magnet 11 is a bonded magnet using a resin as a binder, and the rotating member 108 maintains the outer diameter so that the outer diameter portion of the rotor magnet 111 does not break due to centrifugal force during high-speed rotation. It is. By press-fitting and fixing the rotor magnet 111, it is possible to maintain the high accuracy of the rotating body balance without causing further movement of the fixed portion even at a higher speed and in a high temperature environment.

  The radial bearing includes an outer diameter of the rotating shaft 110 and an upper bearing 105 and a lower bearing 106 disposed above and below the fixed sleeve 103, and is constituted by an oil-impregnated bearing. The axial bearing is a pivot bearing in which a thrust curved surface 110a formed on the lower end surface of the rotating shaft 110 and a thrust receiving member 107 are brought into contact with the opposed surface.

  When the rotating body 102 is rotated at a high speed of 25,000 rpm or higher, the balance of the rotating body 102 must be corrected and maintained with high accuracy in order to reduce vibration. The rotating body 102 has an unbalance correcting portion, and a balance is obtained by applying an adhesive to the circumferential recess 108i or 108k of the rotating member 108 on the upper side of the center of gravity G and the lower side to the circumferential recess 108h. Make corrections. In addition, when it is difficult to manage with a deposit such as an adhesive when performing a minor correction, or when the amount is small, the adhesive force is weak, and when it rotates at a high speed of 40,000 rpm or more, it peels off and scatters. It is preferable to carry out a method (cutting with a drill or laser processing) for deleting a part of a part of the rotating body.

JP 11-271654 A JP 2003-177346 A

  However, in the above-mentioned conventional example, the diameter of the balance correction portion is small and the correction efficiency is poor. In addition, the surface accuracy of the reflecting surface of the rotating polygon mirror deteriorates due to the fixing pressure of the rotating polygon mirror pressing spring, and the image quality deteriorates. Further, since the balance correcting groove is provided, the surface accuracy of the rotating polygon mirror reflecting surface is deteriorated due to the centrifugal force caused by the rotation, and the image quality is deteriorated.

  Further, when the diameter of the balance correcting portion is increased with the same configuration, the fixing position of the rotary polygon mirror pressing spring and the balance correction groove approach the rotary polygon mirror reflecting surface, and the surface accuracy of the rotating polygon mirror reflecting surface is further deteriorated.

  An object of the present invention is to provide a deflection scanning apparatus that solves the above-mentioned problems, has good balance correction efficiency, and reduces deterioration of surface accuracy of a rotating polygon mirror reflecting surface.

  In order to achieve the above object, a deflection scanning apparatus according to the present invention is a deflection scanning apparatus in which a plurality of beams are separated in the rotation axis direction and incident on a rotating polygon mirror reflecting surface, and the rotating polygon mirror reflecting surface is incident. A rotary polygon mirror that is divided into a plurality of parts in the direction of the rotation axis according to the position, a motor that rotationally drives the rotary polygon mirror, bearing means that rotatably supports a rotary member that is integral with the rotary polygon mirror, a rotary polygon mirror, and a motor. A rotating body including a rotating part and a rotating member is provided, and in the rotary polygon mirror, a non-reflective surface between the separated reflecting surfaces is used as a balance correcting part of the rotating body.

  Further, the balance of the rotating body may be corrected by one surface only by the balance correcting portion of the non-reflecting surface between the separated reflecting surfaces.

  Further, the non-reflecting surface between the separated reflecting surfaces may have a radius larger than the inscribed circle radius of the reflecting surface.

  Further, the non-reflecting surface between the separated reflecting surfaces may have a radius smaller than the inscribed circle radius of the reflecting surface.

  Further, in the non-reflecting surface between the separated reflecting surfaces, a radial direction surface may be used as the balance correcting unit.

  Further, in the non-reflecting surface between the separated reflecting surfaces, a surface in the thrust direction may be used as the balance correcting portion.

  Further, in the non-reflective surface between the separated reflecting surfaces, an annular balance correction groove may be provided on the radial surface, and the balance correction groove may be used as the balance correction portion.

  Further, in the non-reflective surface between the separated reflective surfaces, an annular balance correction groove may be provided on the surface in the thrust direction, and the balance correction groove may be used as the balance correction portion.

  According to the present invention, the deviation in the axial direction of the center of gravity of the rotating body and the balance correction unit is reduced, and one-side correction is possible in addition to the two-side correction of balance correction.

  In addition, since the non-reflective surface formed between the separated reflecting surfaces and having a larger diameter than the reflecting surface is used as the balance correcting portion, the diameter of the balance correcting portion is increased, and the amount of balance weight attached can be reduced. Efficient balance correction can be performed. In addition, due to the fixing pressure of the rotating polygon mirror pressing spring and the groove for correcting the balance, the surface accuracy of the reflecting surface of the rotating polygon mirror is deteriorated, and there is no fear of deteriorating the image quality. In addition, there is an effect of preventing scratches and dirt on the reflecting surface of the rotating polygon mirror, and handling of the rotating polygon mirror becomes easy.

  Also, by making the non-reflective surface formed between the separated reflecting surfaces smaller in diameter than the reflecting surface as the balance correcting portion, the diameter of the balance correcting portion increases, and the amount of balance weight attached can be reduced. Efficient balance correction can be performed. In addition, due to the fixing pressure of the rotating polygon mirror pressing spring and the groove for correcting the balance, the surface accuracy of the reflecting surface of the rotating polygon mirror is deteriorated, and there is no fear of deteriorating the image quality. Furthermore, the adhesion strength of the balance weight with respect to the balance correction unit is greatly improved, and it is possible to provide a high-performance deflection scanning device with excellent durability by avoiding troubles such as separation and scattering of the balance weight due to centrifugal force. it can.

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

<Embodiment 1>
FIG. 1 shows a deflection scanning apparatus according to Embodiment 1 of the present invention, which includes a rotary polygon mirror 1, a shaft 2 that is a rotating member that rotates integrally with the rotary polygon mirror 1, and A sleeve 3 is rotatably fitted, and the sleeve 3 is integral with the bearing housing 4. A thrust plate 6 that supports the spherical lower end of the shaft 2 in the thrust direction is fixed to the lower end of the sleeve 3, and a flange member 7 is fixed to the upper portion of the shaft 2.

  The rotary polygon mirror 1 is fixed to the upper surface of the flange member 7 by a method such as adhesion, and is integrated therewith, and is configured to rotate together with the shaft 2.

  A rotor 8 that is a rotating part of the motor is fixed to the outer peripheral portion of the flange member 7, and the rotor 8 is disposed so as to face the stator 9 on the motor substrate 5 fixed to the bearing housing 4. Yes. When the stator 9 is excited by a drive current supplied from a drive circuit (not shown), the rotor 8 rotates together with the shaft 2 and the rotary polygon mirror 1.

  The sleeve 3 forms a rotary bearing means that forms a fluid film with the shaft 2 by the rotation of the shaft 2 and rotates and supports the shaft 2 in a non-contact manner by the dynamic pressure of the fluid film. A first dynamic pressure generating groove and a second dynamic pressure generating groove (not shown) are formed on the outer peripheral surface of the shaft 2 with an interval upward from the lower end of the shaft 2. As the shaft 2 rotates, a lubricant or the like filled in the bearing gap with the sleeve 3 is sucked into the central portion of each dynamic pressure generating groove to generate a high pressure region. The high pressure region supports the shaft 2 and the sleeve 3 in a non-contact state in the radial direction. The bearing in the thrust direction is composed of a convex curved surface formed on the lower end surface of the rotating shaft 2 and a pivot bearing that makes the thrust plate 6 contact the opposite surface.

  The rotary polygon mirror 1 has reflection surfaces 1a and 1b formed at the upper and lower end portions in the axial direction, and a non-reflection surface 1c formed at the central portion in the axial direction. The reflecting surfaces 1a and 1b of the rotary polygon mirror 1 have an area sufficient to deflect a plurality of incident laser beams, that is, a length in the axial direction, and have a non-reflecting surface therebetween. The non-reflective surface 1c is formed with a larger diameter than the reflective surfaces 1a and 1b. The non-reflective surface 1c may have a radius larger than the inscribed circle radius of the reflective surfaces 1a and 1b.

  When the rotating polygonal mirror 1 is rotated at a high speed, a dynamic imbalance occurs due to an unbalance of the mass of the entire rotating body including the rotating polygonal mirror 1, the flange member 7, the rotor 8 and the like, and the whirling vibration caused by this. For this reason, the image quality of the image forming apparatus may be deteriorated.

  Therefore, the unbalance of the mass of the rotating body is reduced by bonding a balance weight or the like. The flange portion of the rotor 8 is provided with an annular balance correcting groove 10 which is a balance correcting portion, and the rotating polygon mirror non-reflecting surface is used as the balance correcting portion. If the balance correcting groove is provided on the surface 1f, the surface accuracy of the rotating polygon mirror reflecting surface 1a is deteriorated due to the centrifugal force of rotation. However, if the balance correcting groove is provided on the surfaces 1c, 1d, and 1e, the centrifugal force of rotation is reduced. Therefore, balance correction grooves may be provided on the surfaces 1c, 1d, and 1e in order not to deteriorate the surface accuracy of the rotating polygon mirror reflecting surfaces 1a and 1b. Then, a balance weight or the like is added to the balance correction groove of the rotor 8 and the balance correction portion (the balance correction groove provided on the surfaces 1c, 1d, 1e or the surfaces 1c, 1d, 1e) of the rotating polygon mirror non-reflecting surface. Perform surface correction. Alternatively, a balance weight or the like is added only to the balance correcting portion (the surfaces 1c, 1d, 1e or the balance correcting grooves provided on the surfaces 1c, 1d, 1e) of the non-reflecting surface of the rotating polygon mirror to correct one surface of the balance.

  When adding the balance weight, the axial length of the rotating polygon mirror reflecting surface and the non-reflecting surface and the axial height of the balance weight are adjusted and restricted so that the added balance weight does not contact the laser beam.

  The balance correction may be performed by removing predetermined portions of the rotary polygon mirror 1 and the rotor 8 by cutting or the like without adding a balance weight or the like to the balance correction unit.

  In addition, you may combine the balance correction which adds a balance weight to a balance correction groove | channel, and the balance correction which removes a part of a rotary polygon mirror or a rotor locally, and forms a notch part. Moreover, you may use an air bearing and a ball bearing, without being limited to the dynamic pressure bearing which uses a lubricant etc.

  Thus, in the present embodiment, a deflection scanning device in which a plurality of beams are separated in the rotation axis direction and incident on the rotating polygon mirror reflecting surface, and the rotating polygon mirror reflecting surface depends on the incident position in the rotation axis direction. A rotary polygon mirror that is separated into a plurality of parts, a motor that rotationally drives the rotary polygon mirror, bearing means that rotatably supports a rotary member that is integral with the rotary polygon mirror, a rotary polygon mirror, a rotating part of the motor, and a rotary member In the rotary polygon mirror having a rotating body, the non-reflective surface between the separated reflecting surfaces is used as a balance correcting section of the rotating body. The deviation of the direction is reduced, and only one-side correction is possible in addition to the two-side correction of balance correction.

  In addition, since the non-reflective surface formed between the separated reflecting surfaces and having a larger diameter than the reflecting surface is used as the balance correcting portion, the diameter of the balance correcting portion is increased, and the amount of balance weight attached can be reduced. Efficient balance correction can be performed.

  Furthermore, there is no fear that the surface accuracy of the reflecting surface of the rotating polygon mirror deteriorates and the image quality deteriorates due to the fixing pressure of the rotating polygon mirror pressing spring and the groove for correcting the balance. In addition, there is an effect of preventing scratches and dirt on the reflecting surface of the rotating polygon mirror, and handling of the rotating polygon mirror becomes easy.

<Embodiment 2>
FIG. 2 shows a deflection scanning apparatus according to the second embodiment. Components that are the same as those in FIG. 1 and that have the same functions are denoted by the same reference numerals and description thereof is omitted.

  In FIG. 2, the rotary polygon mirror 1 has reflection surfaces 1a and 1b formed at the upper and lower end portions in the axial direction, and a non-reflection surface 1g formed at the central portion in the axial direction. The non-reflective surface 1g is formed with a smaller diameter than the reflective surfaces 1a and 1b. The non-reflecting surface 1c may have a radius smaller than the inscribed circle radius of the reflecting surfaces 1a and 1b.

  The flange portion of the rotor 8 is provided with an annular balance correcting groove 10 which is a balance correcting portion, and the rotating polygon mirror non-reflecting surface is used as the balance correcting portion. If the balance correction grooves are provided on the surfaces 1f, 1h, 1i, the surface accuracy of the rotary polygon mirror reflecting surfaces 1a, 1b is deteriorated due to the centrifugal force of rotation, but if the balance correction grooves are provided on the surface 1g, the rotational centrifugal force Therefore, since the surface accuracy of the rotary polygon mirror reflecting surfaces 1a and 1b is not deteriorated, a balance correcting groove may be provided on the surface 1g. Then, a balance weight or the like is added to the balance correction groove of the rotor 8 and the balance correction portion (the balance correction groove provided on the surface 1g, 1h, 1i or the surface 1g) of the rotating polygon mirror non-reflecting surface to perform two-sided balance correction. . Further, a balance weight or the like is added only to the balance correcting portion (the surface 1g, 1h, 1i or the balance correcting groove provided on the surface 1g) of the non-reflecting surface of the rotating polygon mirror to correct one surface of the balance.

  The balance correction may be performed by removing predetermined portions of the rotary polygon mirror 1 and the rotor 8 by cutting or the like without adding a balance weight or the like to the balance correction unit.

  In addition, you may combine the balance correction which adds a balance weight to a balance correction groove | channel, and the balance correction which removes a part of a rotary polygon mirror or a rotor locally, and forms a notch part.

  Moreover, you may use an air bearing and a ball bearing, without being limited to the dynamic pressure bearing which uses a lubricant etc.

  As described above, in the present embodiment, the non-reflective surface formed between the separated reflecting surfaces and having a smaller diameter than the reflecting surface is used as the balance correcting unit. The amount of weight attached can be reduced, and an efficient balance correction can be performed.

  In addition, due to the fixing pressure of the rotary polygon mirror holding spring and the groove for correcting the balance, the surface accuracy of the rotary polygon mirror reflecting surface is not deteriorated, and there is no fear of deteriorating the image quality.

  Furthermore, the adhesion strength of the balance weight with respect to the balance correction portion is greatly improved, and it is possible to provide a high-performance deflection scanning apparatus with excellent durability by avoiding troubles such as separation and scattering of the balance weight due to centrifugal force. it can.

  FIG. 3 shows the entire deflection scanning apparatus, which includes a light source 51 that generates a light beam (light beam) such as a laser beam, and a cylindrical beam that condenses the light beam linearly on the reflecting surface of the rotary polygon mirror 1. A lens 51a, which deflects and scans the light beam by the rotation of the rotary polygon mirror 1, passes through an imaging lens system 52 as an imaging optical system, and a folding mirror 53. To form an image. The imaging lens system 52 includes a spherical lens 52a, a toric lens 52b, and the like, and has an fθ function for correcting the scanning speed of a point image formed on the photosensitive member 54.

  When the rotary polygon mirror 1 is rotated in the direction of the arrow A by the motor, the reflection surface rotates around the axis of the rotary polygon mirror 1 at a constant speed. As described above, the angle formed by the optical path of the light beam generated from the light source 51 and collected by the cylindrical lens 51a and the normal line of the reflecting surface of the rotary polygon mirror 1, that is, the incident angle of the light beam with respect to the reflecting surface is As the rotary polygon mirror 1 rotates, it changes with time and the reflection angle also changes. Therefore, the point image formed by condensing the light beam on the photosensitive member 54 moves in the axial direction (main scanning direction) of the rotary drum. (Scan).

  The imaging lens system 52 condenses the light beam reflected by the rotary polygon mirror 1 into a point image having a predetermined spot shape on the photosensitive member 53, and the scanning speed of the point image in the main scanning direction is constant. Is designed to keep

  The point image formed on the photosensitive member 54 forms an electrostatic latent image in accordance with the main scanning by the rotation of the rotary polygon mirror 1 and the sub scanning by the rotation of the rotating drum having the photosensitive member 54 about its axis. To do.

  Around the photoconductor 54, a charging device for uniformly charging the surface of the photoconductor 54, a developing device for developing an electrostatic latent image formed on the surface of the photoconductor 54 into a toner image, A transfer device (none of which is not shown) for transferring the toner image to the recording paper is disposed, and the recording information by the light beam generated from the light source 51 is printed on the recording paper or the like.

  The detection mirror 55 reflects the light beam upstream of the optical path of the light beam incident on the recording information writing start position on the surface of the photoreceptor 54 in the main scanning direction, and receives the light receiving element 56b having a photodiode or the like through the lens 56a. To the light receiving surface. The light receiving element 56b outputs a scanning start signal for detecting a scanning start position (writing position) when the light receiving surface is irradiated with the light beam.

  The light source 51 generates a light beam corresponding to the signal given from the processing circuit 57 that processes information from the host computer. The signal given to the light source 51 corresponds to information to be written on the photoconductor 54, and the processing circuit 57 displays information corresponding to one scanning line that is a locus formed by a point image formed on the surface of the photoconductor 54. A signal to be expressed is given to the light source 51 as a unit. This information signal is transmitted in synchronization with a scanning start signal given from the light receiving element 56b via the line 56c.

  The rotating polygon mirror 1 and the imaging lens system 52 are accommodated in the optical box 50, and the light source 51 and the like are attached to the side wall of the optical box 50. After the rotary polygon mirror 1 and the imaging lens system 52 are assembled to the optical box 50, a lid (not shown) is attached to the upper opening of the optical box 50.

FIG. 3 is a half sectional view of the deflection scanning apparatus according to the first embodiment of the present invention. FIG. 6 is a half sectional view of a deflection scanning apparatus according to a second embodiment of the present invention. It is a figure explaining the whole deflection scanning apparatus. It is a figure which shows the deflection | deviation scanning apparatus which has the conventional rotary polygon mirror pressing spring. It is a figure which shows the deflection | deviation scanning apparatus which has the conventional balance groove | channel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotation polygon mirror 1a, 1b Rotation polygon mirror reflective surface 1c-1c Rotation polygon mirror non-reflective surface 2 Rotating shaft 3 Sleeve 7 Flange member 10 Balance correction groove

Claims (8)

  A deflection scanning device in which a plurality of beams are separated in a rotation axis direction and incident on a reflecting surface of the rotating polygon mirror, and the rotating polygon mirror reflecting surface is divided into a plurality of rotation axis directions according to the incident position; A motor that rotationally drives the rotary polygon mirror; bearing means that rotatably supports a rotary member that is integral with the rotary polygon mirror; and a rotary body that includes the rotary polygon mirror, a rotating portion of the motor, and the rotary member. In the rotary polygon mirror, a non-reflective surface between the separated reflective surfaces is used as a balance correction unit of the rotating body.   2. The deflection scanning apparatus according to claim 1, wherein the balance of the rotating body is corrected by one surface only by the balance correcting portion of the non-reflecting surface between the separated reflecting surfaces.   2. The deflection scanning apparatus according to claim 1, wherein the non-reflecting surface between the separated reflecting surfaces has a radius larger than an inscribed circle radius of the reflecting surface.   2. The deflection scanning apparatus according to claim 1, wherein the non-reflecting surface between the separated reflecting surfaces has a radius smaller than an inscribed circle radius of the reflecting surface.   4. The deflection scanning apparatus according to claim 2, wherein a radial correction surface is used as a balance correction portion among the non-reflection surfaces between the separated reflection surfaces.   4. The deflection scanning device according to claim 2, wherein a non-reflective surface between the separated reflective surfaces has a surface in the thrust direction as a balance correction unit.   3. The deflection scanning apparatus according to claim 2, wherein an annular balance correcting groove is provided on a radial surface of the non-reflecting surfaces between the separated reflecting surfaces, and the balance correcting groove serves as a balance correcting portion.   4. The deflection scan according to claim 2, wherein an annular balance correction groove is provided on a surface in a thrust direction among the non-reflection surfaces between the separated reflection surfaces, and the balance correction groove serves as a balance correction portion. apparatus.

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