JP2007171503A - Optical deflector, optical scanner, image forming apparatus and method of manufacturing optical deflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resource-saving, reliable and inexpensive optical deflector in which stacked polygon mirrors are accurately positioned and fixed, and to provide an optical scanner, an image forming apparatus and a method of manufacturing the optical deflector. <P>SOLUTION: The plurality of polygon mirrors are stacked in the rotating axis direction and the deflection reflecting faces of the polygon mirrors of respective stages are dislocated by a predetermined amount in the rotating direction and fixed, whereby the stacked polygon mirrors of the optical deflector are accurately positioned and fixed, thus the resource-saving, reliable and inexpensive optical deflector, the optical scanner, the image forming apparatus and the method of manufacturing the optical deflector are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical deflector, an optical scanning device, an image forming apparatus, and an optical deflector manufacturing method used in a color image forming apparatus.

As an optical deflector used in a color image forming apparatus such as a color copying machine, a color printer, a color facsimile machine, etc., a plurality of polygon mirrors are stacked in the direction of the rotation axis, and the deflection reflection surface of each stage of the polygon mirror is in the rotation direction ( An optical deflector that is fixed at a predetermined angular deviation in the circumferential direction) is disclosed.
This color image forming apparatus can output images at high speed while reducing the number of light sources of the optical scanning device, and as an image forming apparatus, resource saving and cost reduction are possible. Further, since the failure probability of the light source can be reduced by reducing the number of light sources, the reliability of the image forming apparatus can be improved (see, for example, Patent Document 1).
JP 2005-92129 A

However, in the conventional optical deflector, since there is no reference plane for determining the position of the stacked polygon mirror, it cannot be fixed with a predetermined angle shift in the rotational direction with high accuracy.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to accurately position and fix a polygonal mirror in which optical deflectors are stacked, and to save resources, high reliability, and low cost, an optical deflector, an optical scanning device, and an image forming apparatus. And a method of manufacturing an optical deflector.

  According to a first aspect of the present invention, in the optical deflector in which a rotating body to which a polygonal mirror is fixed is driven to rotate, a plurality of the polygonal mirrors are stacked in the direction of the rotation axis, and the deflection reflection surface of the polygonal mirror at each stage rotates. It has a polyhedral mirror fixed at a predetermined angle in the direction.

  According to a second aspect of the present invention, in the optical deflector in which a rotating body to which a polygon mirror is fixed is supported by a bearing and is driven to rotate by a motor, a plurality of the polygon mirrors are stacked in the rotation axis direction, The deflecting / reflecting surface of the polygon mirror is fixed at a predetermined angle in the rotation direction, and the effective area of the deflecting / reflecting surface is configured to be biased in the direction of the rotation axis of the polygon mirror, for adjusting the fixed position parallel to the deflecting / reflecting surface. A polyhedral mirror having a reference surface is provided.

  According to a third aspect of the present invention, in the optical deflector according to the first or second aspect, the optical deflector includes a pressing member that is fixed to the rotating body so that the plurality of polygon mirrors are simultaneously pressed and fixed. Features.

  According to a fourth aspect of the present invention, in the optical deflector according to the third aspect, the pressing member is a leaf spring member that is elastically deformed in the rotation axis direction.

  According to a fifth aspect of the present invention, in the optical deflector according to the first or second aspect, the polygon mirrors are arranged such that the deflection reflection surfaces or the fixed position adjustment reference surfaces are adjacent to each other in the rotation axis direction. The above-mentioned polygon mirrors are stacked.

  According to a sixth aspect of the present invention, in the optical deflector according to the first or second aspect, the deflection reflection surface and the fixed position adjusting reference surface are formed on the same continuous plane.

  According to a seventh aspect of the present invention, in the optical deflector according to the first or second aspect, a groove is formed between the deflection reflection surface and the fixed position adjustment reference surface, and the deflection reflection surface and the fixed position adjustment. The reference plane for use is formed by simultaneous machining.

  The invention according to claim 8 is an optical deflector manufacturing method for manufacturing the optical deflector according to any one of claims 1 to 7, wherein an assembly jig is provided on the reference plane for fixed position adjustment. The polygonal mirror is fixed to the rotating body in a state in which the polygonal mirror is brought into contact with each other and the position in the rotational direction of the polygonal mirror is adjusted.

  The invention described in claim 9 includes the optical deflector according to any one of claims 1 to 7 and a semiconductor laser, and a beam from the semiconductor laser is transmitted through an optical system including the optical deflector. A beam spot is formed by being guided to a surface to be scanned, and deflected by the optical deflector, thereby scanning the beam on the surface to be scanned.

  According to a tenth aspect of the present invention, there is provided an optical deflector according to any one of the first to seventh aspects, at least one semiconductor laser, splitting means for splitting a beam from the semiconductor laser into a plurality, and the splitting means A plurality of beams from the scanning surface through an optical system including the optical deflector to form a plurality of light spots and deflected by the optical deflector. The beam is adjacently scanned.

  According to an eleventh aspect of the present invention, there is provided an optical scanning device according to the eighth or ninth aspect, wherein the latent image is formed by optically scanning the photosensitive surface of the photosensitive medium, and an image forming means for obtaining an image by visualizing the latent image An image forming apparatus comprising:

  According to the present invention, a plurality of polygon mirrors are stacked in the direction of the rotation axis, and the deflecting reflection surface of each stage of the polygon mirror is provided with a polygon mirror body fixed at a predetermined angular deviation in the rotation direction. Provided a manufacturing method of an optical deflector, an optical scanning device, an image forming apparatus, and an optical deflector which can accurately position and fix the stacked polygon mirrors, and save resources, high reliability and low cost. Can be realized.

  One embodiment of the optical deflector according to the present invention is an optical deflector in which a rotating body to which a polygonal mirror is fixed is driven to rotate. A plurality of polygonal mirrors are stacked in the rotation axis direction, and the deflection reflection of the polygonal mirrors at each stage is performed. A polyhedral mirror having a surface fixed at a predetermined angle in the rotational direction is provided.

  According to this optical deflector, a plurality of polygon mirrors are stacked in the direction of the rotation axis, and the deflection reflectors of the polygon mirrors at each stage are provided with a polygon mirror that is fixed at a predetermined angle in the rotation direction. It is possible to provide a structure for accurately positioning and fixing the provided polygonal mirror at a predetermined angle.

  In another embodiment of the optical deflector according to the present invention, in a light deflector in which a rotating body to which a polygon mirror is fixed is supported by a bearing and rotated by a motor, a plurality of polygon mirrors are stacked in the rotation axis direction. The deflection reflection surface of each stage of the polygon mirror is fixed at a predetermined angle in the rotation direction, and the effective area of the deflection reflection surface is biased in the direction of the rotation axis of the polygon mirror, and the fixed position adjustment is parallel to the deflection reflection surface. A polyhedral mirror having a reference plane for use is provided.

  According to this optical deflector, a plurality of polygon mirrors are stacked in the direction of the rotation axis, the deflection reflection surfaces of the polygon mirrors at each stage are fixed at a predetermined angle in the rotation direction, and the effective area of the deflection reflection surface is the polygon mirror. The multi-faced mirror body that is biased in the direction of the rotation axis and is formed with a reference surface for fixed position adjustment that is parallel to the deflecting reflecting surface is positioned with high accuracy at a predetermined angle. A fixing structure can be provided.

  Another embodiment of the optical deflector according to the present invention is characterized in that, in addition to the above-described configuration, a pressing member is provided that is fixed to a rotating body so that a plurality of polygon mirrors are simultaneously pressed and fixed.

  According to this optical deflector, by providing a pressing member that is fixed to a rotating body so that a plurality of polygonal mirrors are pressed at the same time, the number of parts necessary for fixing the polygonal mirror is reduced, and assembly is performed. Can be easily.

  Another embodiment of the optical deflector according to the present invention is characterized in that, in addition to the above configuration, the pressing member is a leaf spring member that is elastically deformed in the rotation axis direction.

  According to this optical deflector, since the pressing member is a leaf spring member that is elastically deformed in the direction of the rotation axis, deformation due to assembly can be reduced, and the surface accuracy of the polygon mirror can be maintained with high accuracy.

  In another embodiment of the optical deflector according to the present invention, in addition to the above-described configuration, the polygon mirror includes a polygon mirror so that the deflection reflection surface sides or the fixed position adjustment reference surface sides are adjacent to each other in the rotation axis direction. It is characterized by being stacked.

  According to this optical deflector, the polygon mirror is assembled by arranging the polygon mirrors so that the deflection reflection surfaces or the fixed position adjustment reference surfaces are adjacent to each other in the rotation axis direction. Sometimes assembly can be facilitated without damaging the effective area of the deflecting and reflecting surface of the polygon mirror.

  Another embodiment of the optical deflector according to the present invention is characterized in that, in addition to the above configuration, the deflection reflection surface and the fixed position adjustment reference surface are formed on the same continuous plane.

  According to this optical deflector, since the deflection reflection surface and the fixed position adjustment reference surface are formed on the same continuous plane, the parallelism between the deflection reflection surface and the fixed position adjustment reference surface is improved. The accuracy of the angle of deviation of the polygon mirror can be increased.

  In another embodiment of the optical deflector according to the present invention, in addition to the above configuration, a groove is formed between the deflection reflection surface and the fixed position adjustment reference surface, and the deflection reflection surface and the fixed position adjustment reference surface are It is characterized by being formed by simultaneous processing.

  According to this optical deflector, a groove is formed between the deflection reflection surface and the fixed position adjustment reference surface, and the deflection reflection surface and the fixed position adjustment reference surface are formed by simultaneous processing. The fixed position adjustment reference surface absorbs excess stress during assembly and does not deteriorate the surface accuracy of the deflecting / reflecting surface after assembly.

  An embodiment of the optical deflector manufacturing method according to the present invention is an optical deflector manufacturing method for manufacturing any of the above optical deflectors, wherein an assembly jig is brought into contact with a fixed position adjusting reference plane. The polygon mirror is fixed to the rotating body in a state where the position of the polygon mirror in the rotation direction is adjusted.

  According to this method of manufacturing an optical deflector, a jig for assembly is brought into contact with a reference surface for fixing position adjustment, and the polygon mirror is fixed in a state in which the position of the polygon mirror in the rotation direction is adjusted. In the optical deflector in which the deflecting reflecting surface of the polygon mirror is fixed at a predetermined angle in the rotation direction, the polygon mirror can be positioned and fixed with a predetermined angle with high accuracy.

  An embodiment of an optical scanning device according to the present invention includes any one of the above optical deflectors and a semiconductor laser, and guides a beam from the semiconductor laser to a surface to be scanned through an optical system including the optical deflector. Thus, a light spot is formed and deflected by an optical deflector, whereby the beam is scanned on the surface to be scanned.

  According to this optical scanning device, the number of parts and materials of the light source section can be reduced, the environmental load can be reduced, and the failure probability of the light source can be kept low.

  Another embodiment of the optical scanning device according to the present invention includes any one of the above optical deflectors, at least one semiconductor laser, a dividing unit that divides a beam from the semiconductor laser into a plurality, and a plurality of units from the dividing unit. The beam is guided to the surface to be scanned through an optical system including an optical deflector to form a plurality of light spots and deflected by the optical deflector so that the plurality of beams on the surface to be scanned are adjacently scanned. It is characterized by that.

  According to this optical scanning device, the number of parts and materials of the light source section can be reduced, the environmental load can be reduced, and the failure probability of the light source can be kept low.

  An embodiment of the image forming apparatus according to the present invention includes any one of the above optical scanning apparatuses that forms a latent image by optically scanning a photosensitive surface of a photosensitive medium, and an image forming unit that visualizes the latent image to obtain an image. It is characterized by comprising.

  According to this image forming apparatus, it is possible to reduce the number of parts and materials of the light source unit of the optical scanning device, and to reduce the environmental load.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

Next, an embodiment of the optical deflector according to the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view showing an embodiment of an optical deflector according to the present invention.
In FIG. 1, a rotating body 101 of an optical deflector includes a flange 103 shrink-fitted on the outer periphery of a bearing shaft 102, two polygon mirrors 104 and 105 stacked on the flange 103, and a mirror presser as a pressing member. 106 and a rotor magnet 107.

The radial bearing is an oil-impregnated bearing including a bearing shaft 102 and a fixed sleeve 108, and the bearing gap is set to be 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 generating groove is provided on the outer peripheral surface of the bearing shaft 102 or the inner peripheral surface of the fixed sleeve 108, and is preferably provided on the inner periphery of the fixed sleeve 108 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 107 is fixed to the lower inner surface of the flange 103 and constitutes an outer rotor type brushless motor together with a stator core 109 (winding coil 109a) fixed to the bearing housing 111. The rotor magnet 107 is a bonded magnet using a resin as a binder, and the outer diameter portion of the rotor magnet 107 is held by the flange 103 so as not to be broken due to centrifugal force during high-speed rotation. By press-fitting and fixing the rotor magnet 107, it is possible to maintain a high accuracy in the balance of the rotating body without causing fine movement of the fixed portion even in a higher speed rotation and in a high temperature environment.

  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 is made of martensitic stainless steel or ceramics, or a metal member whose surface is hardened such as DLC (diamond-like carbon) treatment, or a resin material. It is designed to suppress the generation of wear powder.

  The sleeve 108 and the thrust receiver 110 are housed in a bearing housing 111, and the fluid seal 112 prevents oil from flowing out.

  When the rotating body 101 is rotated 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 caused by the rotation. The rotating body 101 has two upper and lower unbalance correction portions, the upper side is coated with an adhesive on the circumferential recess 106 a of the mirror presser 106, and the lower side is coated with the adhesive on the circumferential recess 103 a of the flange 103. To correct the balance. The unbalance amount needs to be 10 mg · mm or less. For example, the correction amount is maintained at 1 mg or less at a location having a radius of 10 mm.

  In addition, when performing such minor corrections as described above, it is difficult to manage with an adhesive or the like, or when the amount is small, the adhesive force is weak, and peeling or scattering occurs during high-speed rotation of 40,000 rpm or more. 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.

The motor system in the present embodiment is a system called an outer rotor type in which a magnetic gap is provided in the radial direction and the rotor magnet 107 is laid out on the outer diameter portion of the stator core 109. The rotation drive is performed by switching the excitation of the winding coil 109a by the drive IC 115, and the rotation control is performed by detecting the magnetic field of the rotor magnet 107 with the Hall element 114 mounted on the circuit board 113 and outputting from the Hall element 114. The rotation control is performed by referring to the signal to be used as the position signal.
The rotor magnet 107 is magnetized in the radial direction, and rotates by generating rotational torque with the outer periphery of the stator core 109. The rotor magnet 107 has a magnetic path open in the outer diameter and height direction other than the inner diameter, and a Hall element 114 for switching excitation of the motor is disposed in the open magnetic path.

Reference numeral 116 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 number of revolutions are input and output.
Four flanged mirrors 104 and 105 are stacked and fixed on the flange 103 in the rotational axis direction (vertical direction in the figure). The flange 103 is shrink-fitted to the bearing shaft 102, and the surface on which the polygon mirror is mounted is processed with high accuracy in flatness and perpendicularity to the bearing shaft 102. The two polygon mirrors 104 and 105 that are stacked are fixed so that their deflecting and reflecting surfaces are shifted by 45 ° in the rotation direction. Effective areas 104a and 105a (see FIG. 2) of the respective deflecting and reflecting surfaces described later are configured to be biased in the rotation axis direction (thickness direction).

  That is, the upper polygon mirror 104 is arranged on the upper side, the lower polygon mirror 105 is arranged on the lower side, and the polyhedral mirror body is configured so that the effective areas 104a and 105a of the deflecting reflection surface are biased. The polyhedral mirrors 104 and 105 of the polyhedral mirror are formed with fixed-position adjusting reference surfaces 104b and 105b as the same plane continuous with effective areas 104a and 105a (see FIG. 2) of the deflecting and reflecting surfaces described later. . The fixed position adjustment reference surfaces 104b and 105b are used as reference surfaces during assembly as described later, and are not used for light deflection.

FIG. 2 is an explanatory view showing an example of a method for manufacturing the rotating body shown in FIG.
Hereinafter, a method for fixing the polygonal mirror by bringing the assembly jig into contact with the reference plane for fixing position adjustment, adjusting the position of the polygonal mirror in the rotational direction will be described with reference to FIG.

In FIG. 2, the jigs 120 and 121 are abutted against the fixed position adjusting reference surfaces 104b and 105b from the left and right sides of the two polygon mirrors 104 and 105 of the polygon mirror, so that the positions of the polygon mirrors 104 and 105 in the rotational direction are changed. Is adjusted. In a state where the position is adjusted and held by the jigs 120 and 121, the leaf spring-like mirror presser 106 is press-fitted into the bearing shaft 102 and fixed to the upper end.
The mirror presser 106 is compressed in the direction of the rotation axis and is elastically deformed and fixed to the tip of the bearing shaft 102 to act as a presser spring, and the two polygon mirrors 104 and 105 are pressed against the flange 103 at the same time. To be fixed.

  The material of the jigs 120 and 121 used for positioning is preferably a resin material having a Young's modulus smaller than that of the polygon mirror so that the deflecting and reflecting surfaces of the polygon mirrors 104 and 105 are not deformed.

  By the above method, the two polygon mirrors 104 and 105 can be accurately positioned and fixed at a predetermined angle (claim 8).

  In the optical deflector according to the first embodiment, the fixed-position adjusting reference surfaces 104b and 105b parallel to the deflecting / reflecting surface are formed, so that the multi-faced mirrors 104 and 105 stacked in the multi-faceted mirror can be accurately positioned at a predetermined angle. It can be positioned and fixed by (claims 1 and 2).

  Further, since the two polygon mirrors 104 and 105 are fixed to the rotating body at the same time using the mirror presser 106 as one pressing member, the number of parts required for fixing the polygon mirrors 104 and 105 is small, and assembly is performed. And the productivity is improved (claim 3).

  Since the leaf spring-like mirror presser 106 is used as the pressing member, excessive stress is absorbed, the deformation of the deflecting / reflecting surface due to assembly is small, and the surface accuracy is kept high.

  Since the fixed position adjustment reference surfaces 104b and 105b are adjacent to each other in the rotation axis direction and the effective areas 104a and 105a of the deflecting / reflecting surfaces are separated from each other, the jigs 120 and 121 for the effective areas 104a and 105a are stacked. It is easy to form a relief portion, and the jigs 120 and 121 can prevent the effective areas 104a and 105a of the deflecting reflection surface from being damaged.

  If the deflection reflection surface and the fixed position adjusting reference surfaces 104b and 105b are in a predetermined relationship, the polyhedral mirror bodies of the stacked polygon mirrors can be accurately positioned and fixed at a predetermined angle. In consideration of workability, it is preferable to form the deflection reflection surface and the fixed position adjustment reference surfaces 104b and 105b as parallel surfaces. Further, as in the first embodiment, if the deflecting reflecting surface and the fixed position adjusting reference surfaces 104b and 105b are configured as the same plane, they can be easily formed by simultaneous processing, with the most accurate predetermined angle. It can be positioned and fixed by (Claim 6).

FIG. 3 is an external perspective view of another embodiment of the optical deflector according to the present invention, and FIG. 4 is a longitudinal sectional view of the optical deflector shown in FIG.
The difference between the optical deflector shown in FIGS. 3 and 4 and the optical deflector shown in FIG. 1 is that only the configuration of the polygon mirror is different.

  In the polygonal mirrors 134 and 135, grooves 134c and 135c are formed between the effective areas 134a and 135a of the deflecting / reflecting surfaces and the fixed position adjusting reference surfaces 134b and 135b. The deflection reflection surfaces 134a and 135a and the fixed position adjustment reference surfaces 134b and 135b are formed by simultaneous processing.

The optical deflector of the second embodiment is also assembled by the same method as that of the first embodiment.
The grooves 134c and 135c are formed between the deflecting / reflecting surfaces 134a and 135a and the fixed position adjustment reference surfaces 134b and 135b, so that the fixed position adjustment reference surfaces 134b and 135b are adjusted when the positions of the polygon mirrors 134 and 135 are adjusted. Stress is not easily transmitted to the effective areas 134a and 135a of the deflecting / reflecting surface, so that the surface accuracy of the deflecting / reflecting surface after assembly does not deteriorate.

FIG. 5 is a conceptual diagram showing an embodiment of an optical scanning device according to the present invention.
The optical deflector shown in the first and second embodiments is used in the optical scanning device shown in FIG.
In FIG. 5, 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 light beams emitted from the semiconductor lasers 1 and 1 ′ are converted into light beam forms (parallel light beams or weakly divergent or weakly convergent light beams) suitable for the subsequent optical system by the coupling lenses 3 and 3 ′, respectively. The In the present embodiment, it is assumed that 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” after passing through the opening of the aperture 12 that regulates the light beam width, and then as a dividing unit. The light enters the half mirror prism 4 and is divided into two in the sub-scanning direction by the action of the half mirror prism 4, and each is divided into two light beams. FIG. 6 shows the light beam splitting state.

FIG. 6 is a conceptual diagram of light beam splitting means in the optical scanning device shown in FIG.
In order to avoid the complexity of the figure, the light beam L1 emitted from the semiconductor laser 1 is shown as a representative.
Although the vertical direction in FIG. 6 is the sub-scanning direction, the half mirror prism 4 has a semi-transparent mirror 4a and a reflecting surface 4b arranged in parallel in the sub-scanning direction.

When the light beam L1 enters the half mirror prism 4, the light beam L1 enters the half mirror 4a, and part of the light beam L1 passes straight through the half mirror 4a to become the light beam L11, and the rest is reflected by the half mirror 4a and reflected on the reflecting surface 4b. Incident light is totally reflected by the reflecting surface 4b to become a light beam L12.
In this example, since the semi-transparent mirror 4a and the reflecting surface 4b are parallel to each other, therefore, 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 manner, two light beams are emitted from one light source (number m = 1), and these two light beams are divided into two in the sub-scanning direction (number of divisions q = 2). Can be obtained.

  Returning to FIG. 5, these four light beams enter the cylindrical lenses 5a and 5b, and are condensed in the sub-scanning direction by the condensing action of the cylindrical lenses 5a and 5b in the curvature direction, so that the polygon mirror light deflection is performed. An image is formed as a “line image long in the main scanning direction” in the vicinity of the deflecting reflection surface of the device 7.

  As shown in FIG. 5, among the light beams emitted from the semiconductor lasers 1 and 1 ′ and divided by the half mirror prism 2, the light beams that pass straight through the half mirror 4 a of the half mirror prism 4 (FIG. 6). 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 in FIG. 6) is incident on the cylindrical lens 5b.

In FIG. 5, reference numeral 6 denotes a part of “soundproof glass” provided in a window of a soundproof housing (not shown) of the polygon mirror type optical deflector 7.
The four light beams from the light source side enter the polygon mirror optical 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 the figure, the polygon mirror optical deflector 7 has an upper polygon mirror 7a and a lower polygon mirror 7b stacked vertically in two stages in the direction of the rotation axis to form a polygon mirror, and around the rotation axis by a drive motor (not shown). It is designed to rotate.

  The upper polygon mirror 7a and the lower polygon mirror 7b are of the same shape having “four deflection reflection surfaces” in this embodiment, but the lower polygon mirror 7b is opposed to the deflection reflection surface of the upper polygon mirror 7a. Is deflected by a predetermined angle: θ (= 45 degrees) in the rotation direction. The upper polygon mirror 7a and the lower polygon mirror 7b are formed separately, but may be formed integrally.

  In FIG. 5, 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 (from the semiconductor lasers 1 and 1 ′) deflected by the upper polygon mirror 7a of the polygon mirror optical deflector 7. The two light beams emitted and transmitted through the semi-transparent mirror 4a of the half mirror prism 4 are guided onto 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 a light spot is constructed.

  The first scanning lens 8b, the second scanning lens 10b, and the optical path bending mirror 9b are composed of two light beams (from the semiconductor lasers 1 and 1 ′) deflected by the lower polygon mirror 7b of the polygon mirror optical deflector 7. The two light beams emitted and reflected by the semi-transparent mirror 4a of the half mirror prism 4 are guided onto the photoconductive photoreceptor 11b which is the corresponding optical scanning position and separated in the sub-scanning direction 2 A set of scanning imaging optical systems for forming one 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 reflection 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 / reflecting surface has an optical beam mutual "open angle (a surface perpendicular to the rotation axes of the two light beams when viewed from the light source side from the deflecting / reflecting surface side). Means the angle formed by the projection onto. 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 by the two light beams deflected by the upper polygon mirror 7a of the polygon mirror optical deflector 7, and the lower polygon mirror of the polygon mirror optical deflector 7 is scanned. The photoconductive photoreceptor 11b is subjected to multi-beam scanning by the two light beams deflected by 7b.

  Since the deflection reflection surface of the upper polygon mirror 7a and the deflection reflection surface of the lower polygon mirror 7b are shifted from each other by 45 degrees in the rotational direction, the deflection light beam from the upper polygon mirror 7a is photoconductive. When the photosensitive photoconductor 11a is optically scanned, the light beam deflected by the lower polygon mirror 7b is not guided to the photoconductive photoconductor 11b.

Similarly, when the light beam deflected by the lower polygon mirror 7b scans 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".

  FIGS. 7A and 7B are explanatory diagrams for explaining the scanning of the light beam in the optical scanning device shown in FIG.

In FIGS. 7A and 7B, in order to avoid complication, “incident light” is a light beam that is incident on the polygon mirror type optical deflector (two in the figure are actually four). The deflected light beam is shown as “deflected light a, deflected light b”.
FIG. 7A 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. 7B 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 while the deflected light from one polygon mirror 7a (7b) is guided to the optical scanning position, the deflected light from the other polygon mirror 7b (7a) does not act as "ghost light". It is preferable to shield the deflected light that is not guided to the optical scanning position by using an appropriate light shielding means SD as shown in (a) and (b).
In practice, this light shielding means SD can be easily realized by making the inner wall of the aforementioned “soundproof housing” non-reflective.

  As described above, in the embodiment shown in FIG. 5, 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 with the “black image signal”, and when the photoconductive photoconductor 11b is scanned, the light intensity of the light source is modulated with the “magenta image signal”. An electrostatic latent image of a black image can be written on the photoconductive photoconductor 11a, and an electrostatic latent image of a magenta image can be written on the photoconductive photoconductor 11b.

FIG. 8 is a diagram showing the scanning timing of the light beam in the optical scanning device shown in FIG. 5, where the consistent axis is the time axis and the vertical axis is the emission intensity axis.
That is, FIG. 8 shows a time chart of “when all the light is lit in the effective scanning region” when writing a black image and a magenta image with the “common light source (semiconductor lasers 1 and 1 ′ in FIG. 5)”. ing. In FIG. 8, 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 optically scanned by the synchronous light receiving means (not shown in FIG. 5, usually a photodiode or phototransistor) provided outside the effective scanning area. It is determined by detecting the light beam toward the starting position.

  According to the optical scanning device of the third embodiment, it is possible to provide a multi-beam optical scanning device in which the number of parts and the material of the light source unit are reduced, the environmental load is reduced, and the failure probability of the light source is reduced. Item 10).

One embodiment of an image forming apparatus according to the present invention will be described with reference to FIGS.
FIG. 9 shows a state in which the optical system portion showing an embodiment of the optical scanning device used in the image forming apparatus according to the present invention is viewed from the sub-scanning direction (the rotational axis direction of the polygon mirror optical deflector 7). FIG.
For the sake of simplicity, 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 so as to be a straight line.

  The optical scanning device shown in FIG. 9 is a case where m = q = 2, p = 1, and n = 4, and each of the four optical scanning positions is optically scanned with one light beam. In addition, photoconductive photoreceptors 11Y, 11M, 11C, and 11K are individually arranged at the optical scanning positions, and electrostatic latent images formed on these four photoconductive photoreceptors are magenta, yellow, cyan, Visualization is individually performed with black toner to form a color image.

  In FIG. 9, 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. Are 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. 5 and 7, and polygon mirrors having four deflecting reflecting surfaces are stacked in two stages in the rotation axis direction. 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 emitted from the semiconductor laser 1CK is converted into a parallel light beam by the coupling lens 3CK, shaped through the aperture 12CK, and then separated into the sub-scanning direction by the half mirror prism 4CK. Are 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.

FIG. 10 is a conceptual diagram showing an embodiment of the image forming apparatus according to the present invention.
In FIG. 10, a portion indicated by reference numeral 20 is an optical scanning device, which is the portion described with reference to FIG. In FIG. 10, charging rollers TY, TM, TC, TK, developing devices GY, GM, GC, GK, GK15K, BK, which are arranged around the photoconductive photoreceptors 11Y to 11K by the optical scanning device 20, respectively. TK, transfer devices 15Y, 15M, 15C, and 15K, the conveyance belt 17, and the fixing device 19 constitute an image forming unit.

  As shown in FIG. 10, one of the light beams deflected by the upper polygon mirror of the polygon mirror type optical deflector 7 is scanned by the optical path bent by the optical path bending mirrors mM1, mM2, and mM3. Is guided to the photoconductive photosensitive member 11M. Similarly, the other light beam is guided to the photoconductive photosensitive member 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 optical deflector 7 is a photoconductive photoconductor that forms the substance of the optical scanning position by the optical path bent by the optical path bending mirror mY. 11Y is guided. Similarly, 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 number m = 2 of the 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. Four 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 at a constant speed in one direction (clockwise in the drawing), and is uniformly charged by the charging rollers TY, TM, TC, and TK that form the charging means, and the corresponding light beams. In response to the optical scanning, 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. In the figure, BY, BM, BC, and BK are squeegees for removing excess toner.

  That is, in the embodiments shown in FIGS. 9 and 10, electrostatic latent images are individually formed on a plurality of photoconductive photoreceptors by optical scanning, and these electrostatic latent images are visualized to obtain toner images. In the tandem type image forming apparatus that transfers the toner image to the same sheet-like recording medium and forms an image synthetically, the number of photoconductive photoconductors is 4, and two optical scanning devices are used. Using the light sources 1YM and 1CK, each light beam from each light source is configured to optically scan two photoconductive photoreceptors.

  In this image forming apparatus, electrostatic latent images formed on the four photoconductive photoreceptors 11M, 11Y, 11C, and 11K are individually visualized with magenta, yellow, cyan, and black toners to form color images. . In this embodiment, the optical scanning of each photoconductive photoconductor is performed by the “single beam method”. However, each light source side is configured as shown in FIG. Of course, it can be done in the “beam mode”.

[Action / Effect]
Claims 1 and 2 In an optical deflector in which a plurality of polygon mirrors are stacked and the deflection reflecting surface is fixed at a predetermined angle in the rotation direction, the stacked polygon mirrors are accurately positioned and fixed at a predetermined angle. A structure can be provided.

According to the third aspect of the present invention, it is possible to provide an optical deflector that requires few parts for fixing the polygon mirror and is easy to assemble.

According to the fourth aspect of the present invention, it is possible to provide an optical deflector in which deformation due to assembly is small and the surface accuracy of the polygonal mirror is maintained with high accuracy.

According to the fifth aspect of the present invention, it is possible to provide an optical deflector that can be easily assembled without damaging the effective area of the deflecting reflecting surface of the polygon mirror during assembly.

According to the sixth aspect of the present invention, it is possible to provide an optical deflector in which the parallelism between the deflecting reflecting surface and the fixed position adjusting reference surface is good, and the accuracy of the deviation angle of the polygon mirror is high.

According to the seventh aspect of the present invention, it is possible to provide an optical deflector that absorbs excessive stress at the time of assembly by the reference surface for adjusting the fixed position and does not deteriorate the surface accuracy of the deflecting / reflecting surface after assembly.

According to the eighth aspect of the present invention, it is possible to provide a manufacturing method in which, in an optical deflector in which the deflecting reflecting surfaces of a plurality of polygon mirrors are fixed at a predetermined angle in the rotation direction, the polygon mirrors are accurately positioned and fixed at a predetermined angle.

According to the ninth aspect of the present invention, it is possible to provide an optical scanning device in which the number of parts and materials of the light source section are reduced, the environmental load is reduced, and the failure probability of the light source is kept low.

According to the tenth aspect of the present invention, it is possible to provide a multi-beam optical scanning device in which the number of parts and materials of the light source section are reduced, the environmental load is reduced, and the failure probability of the light source is kept low.

According to the eleventh aspect of the present invention, it is possible to provide an image forming apparatus in which the number of parts and materials of the light source section of the optical scanning device are reduced and the environmental load is reduced.

  The present invention can be used for an optical deflector, an optical scanning device, an image forming apparatus, and a method of manufacturing an optical deflector used in a color image forming apparatus such as a color copying machine, a color printer, and a color facsimile apparatus.

It is a longitudinal cross-sectional view which shows one Example of the optical deflector which concerns on this invention. It is explanatory drawing which shows an example of the manufacturing method of the rotary body shown in FIG. It is an external appearance perspective view of the other Example of the optical deflector which concerns on this invention. It is a longitudinal cross-sectional view of the optical deflector shown in FIG. It is a conceptual diagram which shows one Example of the optical scanning device concerning this invention. FIG. 6 is a conceptual diagram of light beam splitting means in the optical scanning device shown in FIG. 5. (A), (b) is explanatory drawing for demonstrating the scanning of the light beam in the optical scanning device shown in FIG. It is a figure which shows the scanning timing of the light beam in the optical scanning device shown in FIG. 1 is a diagram showing a state in which an optical system portion showing an embodiment of an optical scanning device used in an image forming apparatus according to the present invention is viewed from a sub-scanning direction (a rotation axis direction of a polygon mirror optical deflector 7). 1 is a conceptual diagram illustrating an embodiment of an image forming apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Rotating body 102 Bearing shaft 103 Flange 104, 105 Polyhedral mirror 106 Mirror presser 107 Rotor magnet 108 Fixed sleeve 109 Stator core 110 Thrust receiving member 111 Bearing housing 112 Fluid seal 113 Circuit board 114 Hall element 115 Drive IC
116 connector

Claims (11)

In an optical deflector in which a rotating body with a polygon mirror fixed is driven to rotate,
An optical deflector comprising: a plurality of polygon mirrors stacked in a rotation axis direction, and a polygon mirror body in which the deflection reflection surfaces of the polygon mirrors at each stage are fixed at a predetermined angle in the rotation direction. In the optical deflector in which the rotating body to which the polygon mirror is fixed is supported by the bearing and is driven to rotate by the motor,
A plurality of the polygon mirrors are stacked in the direction of the rotation axis, and the deflection reflection surfaces of the polygon mirrors at each stage are fixed with a predetermined angle deviation in the rotation direction, and the effective area of the deflection reflection surface is the rotation axis direction of the polygon mirror An optical deflector comprising a multi-faceted mirror body that is configured to be biased toward the surface and is formed with a reference surface for fixed position adjustment parallel to the deflection reflecting surface. The optical deflector according to claim 1 or 2,
An optical deflector comprising: a pressing member that is fixed to the rotating body so that the plurality of polygon mirrors are pressed and fixed simultaneously. The optical deflector according to claim 3, wherein
The optical deflector according to claim 1, wherein the pressing member is a leaf spring member that is elastically deformed in a rotation axis direction. The optical deflector according to claim 1 or 2,
The optical deflector, wherein the polygon mirrors are stacked such that the deflection reflection surfaces or the fixed position adjustment reference surfaces are adjacent to each other in the rotation axis direction. . The optical deflector according to claim 1 or 2,
The optical deflector, wherein the deflecting reflecting surface and the fixed position adjusting reference surface are formed on the same continuous plane. The optical deflector according to claim 1 or 2,
A light is characterized in that a groove is formed between the deflection reflection surface and the fixed position adjustment reference surface, and the deflection reflection surface and the fixed position adjustment reference surface are formed by simultaneous processing. Deflector. An optical deflector manufacturing method for manufacturing the optical deflector according to any one of claims 1 to 7,
An optical deflector, wherein an assembly jig is brought into contact with the fixed position adjustment reference surface, and the polygon mirror is fixed to the rotating body in a state where the position of the polygon mirror in the rotation direction is adjusted. Production method.   An optical spot comprising the optical deflector according to any one of claims 1 to 7 and a semiconductor laser, and a beam from the semiconductor laser is guided to a surface to be scanned through an optical system including the optical deflector. And scanning the beam on the surface to be scanned by deflecting the optical beam by the optical deflector.   The optical deflector according to any one of claims 1 to 7, at least one semiconductor laser, splitting means for splitting a beam from the semiconductor laser into a plurality, and a plurality of beams from the splitting means, A plurality of light spots are formed through an optical system including an optical deflector to form a plurality of light spots and deflected by the optical deflector so that a plurality of beams on the surface to be scanned are adjacently scanned. An optical scanning device.   10. An optical scanning apparatus according to claim 8 or 9, wherein a latent image is formed by optically scanning a photosensitive surface of a photosensitive medium, and image forming means for visualizing the latent image to obtain an image. Image forming apparatus.

Images