JP2006171159A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress variations in beam diameters of light beams on a photosensitive body which are to be generated by the inclination of a light emitting surface. <P>SOLUTION: In an optical scanner of the present invention, a first adjusting screw 54, a second adjusting screw 56 and a fixing pin 58 are projected from a light source supporting surface supporting a light source 12, and they abut on three points of surroundings of the light emitting surface 50. Then, beam diameters of light beams on the photosensitive body are adjusted by adjusting the inclination of the light emitting surface 50 with the first adjusting screw 54 and the second adjusting screw 56. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device that deflects and scans a surface to be scanned with a plurality of light beams emitted from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged.

  In recent laser beam printers, so-called surface-emitting lasers that emit a plurality of light beams from a plurality of light-emitting points arranged two-dimensionally are used as light sources in order to perform high-speed and high-resolution image formation. With this surface emitting laser, scanning with about 30 multi-beams is possible, and for example, 100 sheets can be output per minute at 2400 dpi.

  Incidentally, since the scanning optical system of the optical scanning device includes an optical system for correcting the surface tilt of the polygon mirror, as shown in FIG. 13A, the lateral magnification βt in the main scanning direction and the lateral magnification in the sub-scanning direction. Generally, βs is different. Among them, in the multi-beam scanning optical system, the design constraint on the lateral magnification in the sub-scanning direction becomes particularly strict, such as the lateral magnification in the sub-scanning direction being restricted in order to satisfy the relationship between the light emitting point interval and the scanning line pitch. Therefore, it is difficult to match the horizontal magnification in the main scanning direction and the sub-scanning direction.

For this reason, as shown in FIG. 13B, when an error Δ in the optical axis direction occurs at the position of the light emitting surface 100, the positional deviation amount of the image formation point in the optical axis direction is the main scanning direction. It differs between Δs (= Δ × βt ² ) and the sub-scanning direction Δs (= Δ × βs ² ). As a result, the beam diameter on the surface to be scanned 102 is different between the main scanning direction and the sub-scanning direction. Therefore, a beam that is circular (see FIG. 13A) in the nominal state on the surface to be scanned 102 (Z0). The shape is elliptical. Note that a line image is formed horizontally long at the image forming point Z1 in the sub-scanning direction, and a line image is formed vertically long at the image forming point Z2 in the main scanning direction.

  In FIG. 14A, the light emitting surface 100 is inclined in the main scanning direction or the sub scanning direction with respect to the optical axis 106 of the scanning optical system, so that each light emitting point 104 (see FIG. 14B). This shows a state in which an error in the optical axis direction has occurred at the position. In this case, the imaging point of the light beam emitted from the light emitting point 104 that is separated from the optical axis 106 of the scanning optical system in the main scanning direction or the sub-scanning direction is greatly shifted from the scanned surface 102 in the optical axis direction. For this reason, the beam diameter of the light beam on the surface to be scanned 102 increases as it moves away from the optical axis 106 in the main scanning direction or sub-scanning direction, and the variation in beam shape also increases as it moves away from the optical axis 106. As a result, there is a problem that image quality defects such as density unevenness occur.

  For this reason, in the optical scanning device in which the number of light beams is increased and the difference in distance from the optical axis 106 of the optical system to each light beam is increased, the uniformity of the beam diameter and beam shape of each light beam is maintained. For this reason, it is important to strictly regulate the inclination of the light emitting surface.

In addition, the structure which adjusts the angle of a light emission surface is conventionally well-known (for example, refer patent document 1). However, Patent Document 1 has a problem of reducing the pitch deviation caused by the deviation from the nominal optical path, in which the light emitting surface is inclined in the sub-scanning direction to reduce the curvature of the scanning line. There is no disclosure of an adjustment mechanism for suppressing the difference in the beam diameters or suppressing the image quality defect due to the difference in the beam diameters.
JP 2001-1225026 A

  The present invention has been made in consideration of the above-described fact, and suppresses a difference in beam diameter on a scanned surface of a plurality of light beams emitted from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged, and An object of the present invention is to effectively suppress image quality defects due to a difference in beam diameter.

  The optical scanning device according to claim 1, wherein a light source unit that emits a plurality of light beams from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged, and a surface to be scanned by the plurality of light beams emitted from the light source unit A scanning optical system that deflects and scans the light source unit, and projects from a light source support surface on which the light source unit is supported, abuts on three points surrounding the light emitting surface of the light source unit, The contact point includes three contact points that determine the posture, and at least one of the three contact points is an adjustment contact point capable of adjusting a protruding amount from the light source support surface. And

  In the optical scanning device according to claim 1, the light source unit emits a plurality of light beams from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged, and the scanning optical system includes a plurality of lights emitted from the light source unit. The scanning surface is deflected and scanned with the beam. As a result, high-speed and high-resolution image formation is possible.

  Here, although the light source unit is supported by the light source support surface, three contact points protrude from the light source support surface and contact the three points surrounding the light emitting surface of the light source unit, and the posture of the light emitting surface is determined. It has been. At least one of the three contact points is an adjustment contact point that can adjust the amount of protrusion from the light source support surface. Accordingly, the position of the light emitting surface can be adjusted by adjusting the positional relationship between the three contact points, so that variations in the beam diameters of the plurality of light beams on the surface to be scanned can be corrected. In addition, by bringing the three contact points into contact with the three points surrounding the light emitting surface of the light source unit, the posture of the light emitting surface can be stabilized and assembly errors can be suppressed.

  An optical scanning device according to a second aspect is the optical scanning device according to the first aspect, wherein the light source portion includes a reference surface that is substantially parallel to the light emitting surface and contacts the three contact points. It is characterized by having.

  In the optical scanning device according to claim 2, the light source portion is provided with a reference surface substantially parallel to the light emitting surface, and the three contact points come into contact with the reference surface, whereby the posture of the light emitting surface is determined. Is decided. Here, when a surface emitting laser is mounted on a rectangular package, it is easy to improve the flatness of the package surface and the parallelism between the package surface and the light emitting surface. The assembly accuracy and adjustment accuracy of the light source unit can be ensured.

  The optical scanning device according to claim 3 is the optical scanning device according to claim 1 or 2, wherein the adjustment contact point is an adjustment screw that penetrates the light source support surface and is adjusted from the inside of the device. It is characterized by that.

  In the optical scanning device according to the third aspect, the posture of the light emitting surface is adjusted by adjusting the adjusting screw penetrating the light source support surface from the inside of the device. Thus, since the adjustment contact point is an adjustment screw penetrating the light source support surface and the adjustment unit is provided inside the apparatus, the accuracy of the angle of the light emitting surface can be maintained even when an impact is applied to the optical scanning device.

  The optical scanning device according to claim 4, wherein a light source unit that emits a plurality of light beams from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged, and a surface to be scanned by the plurality of light beams emitted from the light source unit A scanning optical system that deflects and scans the light source, and protrudes from three points surrounding the light emitting surface of the light source unit so as to contact a light source support surface on which the light source unit is supported, It has three contact points that determine the posture, and at least one of the three contact points is an adjustment contact point that can adjust the amount of protrusion from the light source unit. To do.

  In the optical scanning device according to claim 4, the light source unit is supported by the light source support surface, but three contact points project from the three points surrounding the light emitting surface of the light source unit to contact the light source support surface. The posture of the light emitting surface is determined. At least one of the three contact points is an adjustment contact point that can adjust the amount of protrusion from the light source unit. Accordingly, the position of the light emitting surface can be adjusted by adjusting the positional relationship between the three contact points, so that variations in the beam diameters of the plurality of light beams on the surface to be scanned can be corrected. Further, by projecting the three contact points from the three points surrounding the light emitting surface of the light source unit and bringing them into contact with the light source support surface, the posture of the light emitting surface can be stabilized, and assembly accuracy can be maintained.

  An optical scanning device according to a fifth aspect is the optical scanning device according to any one of the first to fourth aspects, wherein the position of the light emitting surface is adjusted by the adjustment contact point, so that the scanned object is adjusted. The beam diameter of the plurality of light beams on the surface is adjusted.

  Here, when the light emitting surface is tilted, the beam diameters of the plurality of light beams on the scanned surface regularly increase as the distance from the optical axis of the scanning optical system increases in the tilt direction of the light emitting surface. This point will be described later in detail.

  Therefore, in the optical scanning device according to claim 5, the beam diameters of a plurality of light beams on the surface to be scanned are adjusted by adjusting the positional relationship of the three contact points by the adjustment contact point to adjust the inclination of the light emitting surface. Adjust. As a result, fluctuations in the beam diameters of the plurality of light beams on the surface to be scanned can be suppressed, so that image quality defects such as density unevenness can be suppressed.

  The optical scanning device according to a sixth aspect is the optical scanning device according to any one of the first to fifth aspects, wherein two of the three contact points are used as the adjustment contact points, respectively. The light emitting surface is disposed on one side and the other side of the light emitting surface in the longitudinal direction, and the other one of the contact points is set as the fixed contact point fixed to the light source support surface or the light source unit. An angle A between a straight line connecting the adjustment contact point and the fixed contact point disposed on one side in the longitudinal direction of the light emitting surface and the longitudinal direction of the light emitting surface, and the longitudinal direction of the light emitting surface A relationship between an angle B between a straight line connecting the adjustment contact point and the fixed contact point disposed on the other side and the short side direction of the light emitting surface is A> B.

  In the optical scanning device according to claim 6, the lengths of the light emitting surfaces in the X direction and the Y direction are different such that the arrangement of the light emitting points is m × n, and the light emitting points at both ends in the longitudinal direction of the light emitting surface. And the optical axis of the scanning optical system are long. For this reason, when the adjustment error of the attitude | position of a light emitting surface becomes large with respect to the longitudinal direction of a light emitting surface, the fluctuation | variation of the beam diameter in a to-be-scanned surface will become large.

  Therefore, in the present invention, the three contact points are arranged so that the adjustment error of the posture of the light emitting surface is reduced with respect to the longitudinal direction of the light emitting surface. Specifically, two of the three contact points are set as adjustment contact points, and are arranged on one side and the other side of the light emitting surface in the longitudinal direction. Then, the light source support part or another fixed contact point fixed to the light source part is disposed on the other side in the longitudinal direction of the light emitting surface, and the adjustment contact point disposed on one side in the longitudinal direction is fixed to the fixed contact point. The angle B between the straight line connecting the contact points and the longitudinal direction of the light emitting surface, and the angle B between the straight line connecting the adjustment contact point and the fixed contact point disposed on the other side of the light emitting surface in the longitudinal direction and the short direction of the light emitting surface. A> B.

  That is, when adjusting the adjustment contact point on one side in the longitudinal direction, the light emitting surface is rotated about a straight line connecting the adjustment contact point on the other side in the longitudinal direction and the fixed contact point. When the light emitting surface is tilted with respect to the short direction, the light emitting surface is adjusted not only with respect to the longitudinal direction but also with respect to the short direction. Further, when adjusting the adjustment contact point on the other side in the longitudinal direction, the light emitting surface is rotated about a straight line connecting the adjustment contact point on one side in the longitudinal direction and the fixed contact point. When the light emitting surface is tilted with respect to the longitudinal direction, the tilt adjustment of the light emitting surface is performed not only with respect to the lateral direction but also with respect to the longitudinal direction.

  For this reason, when the angle B between the straight line connecting the adjustment contact point on the other side in the longitudinal direction and the fixed contact point and the short side direction becomes large, when the inclination adjustment of the light emitting surface is performed with respect to the long side, the short side direction is reached. Thus, the change in the inclination of the light emitting surface becomes large, and the inclination amount with respect to the longitudinal direction of the light emitting surface cannot be changed by a desired amount. Therefore, by adjusting the angle B to be smaller than the angle A between the straight line connecting the adjustment contact point on one side of the longitudinal direction and the fixed contact point and the longitudinal direction, the adjustment error of the tilt adjustment with respect to the longitudinal direction of the light emitting surface is reduced. Suppressed.

  The optical scanning device according to claim 7 is the optical scanning device according to any one of claims 1 to 5, wherein one of the three contact points is set as the adjustment contact point, and the other. These two contact points are generated in the main scanning direction or the sub-scanning direction due to the inclination of the light emitting surface, and the variation in the beam diameters of the plurality of light beams on the scanned surface is larger. It arrange | positions on the substantially perpendicular | vertical straight line, It is characterized by the above-mentioned.

  In the optical scanning device according to claim 7, due to a difference in the width of the light emitting surface in the main scanning direction and the width in the sub scanning direction, a difference in the horizontal magnification in the main scanning direction and the horizontal magnification in the sub scanning direction of the scanning optical system, or the like. The method of changing the beam diameter of the light beam on the surface to be scanned differs between the main scanning direction and the sub-scanning direction.

  Therefore, one of the three contact points is used as an adjustment contact point, and the other two contact points are used as beam diameters of a plurality of light beams on the scanned surface in either the main scanning direction or the sub-scanning direction. The light emitting surface is arranged on a straight line that is substantially perpendicular to the larger variation due to the inclination of the light emitting surface. As a result, the tilt adjustment of the light emitting surface can be performed in the direction in which the beam diameter variation increases due to the tilt of the light emitting surface. The size can be reduced and the occurrence of image quality degradation can be suppressed.

  The optical scanning device according to claim 8 is the optical scanning device according to any one of claims 1 to 5, wherein one of the three contact points is set as the adjustment contact point, and the other. These two contact points are arranged on a straight line substantially parallel to the main scanning direction.

  In the optical scanning device according to the eighth aspect, when fluctuations in the beam diameters of the plurality of light beams on the surface to be scanned occur in the sub-scanning direction, the density change period becomes long and the density unevenness becomes remarkable. Therefore, one of the three contact points is set as an adjustment contact point, and the other two contact points are arranged on a straight line substantially parallel to the main scanning direction. As a result, the tilt adjustment of the light emitting surface can be performed in the sub-scanning direction, so that fluctuations in the beam diameter of the light beam with respect to the sub-scanning direction can be suppressed, and density unevenness can be suppressed.

  The optical scanning device according to claim 9 is the optical scanning device according to any one of claims 1 to 8, wherein the scanning optical system is supported on a bottom surface, and the light source support surface is provided on a side wall. An optical housing, and a housing cover that covers the optical housing, wherein the adjustment contact point is disposed on the housing cover side in the sub-scanning direction, and the other contact point is on the bottom surface side in the sub-scanning direction. It is characterized by being arranged.

  In the optical scanning device according to the ninth aspect, the scanning optical system is supported on the bottom surface of the optical housing, and the light source support surface is provided on the side wall of the optical housing. The optical housing is covered with a housing cover.

  Here, a collimator lens or the like is mounted in the vicinity of the light source unit, and a space for adjusting the adjustment contact point is limited. Therefore, the adjustment contact point is disposed on the housing cover side in the sub-scanning direction, that is, on the open side of the optical housing, and the other contact point is disposed on the bottom surface side in the sub-scanning direction. It is provided away from the bottom surface to ensure freedom of access during adjustment.

  Since the present invention has the above-described configuration, it is possible to suppress a difference in beam diameter on the scanned surface of a plurality of light beams emitted from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged. Defects can be effectively suppressed.

  A first embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, in the optical scanning device 10, a VCSEL control board 14 (hereinafter referred to as a substrate) on which a VCSEL light source section 12 (see FIG. 2, hereinafter referred to as a light source section) is mounted is disposed on the side wall 16 </ b> A of the optical housing 16. Installed. A through hole 16B is formed in the side wall 16A so as to face the light source unit 12, and the light beam L emitted from the light source unit 12 enters the optical housing 16 through the through hole 16B.

  A scanning optical system 15 is disposed on the bottom surface 16 </ b> C of the optical housing 16. The scanning optical system 15 includes a collimator lens 18, an aperture 20, a half mirror 22, a cylindrical lens 24, a polygon mirror 26, an Fθ lens 28, and a first cylindrical mirror 30, which are arranged in order along the optical path of the light beam L. , A folding mirror 32 and a second cylindrical mirror 34.

  The light beam L is converted into a parallel beam by the collimator lens 18 and shaped to a predetermined beam width by the aperture 20. Then, the light passes through the half mirror 22 and enters the cylindrical lens 24, and the cylindrical lens 24 forms an image in the vicinity of the reflection surface of the polygon mirror 26 in a linear shape extending in the main scanning direction.

  The light beam L is deflected by the rotation of the polygon mirror 26 and is converted into a light beam that is scanned at a constant speed by the two Fθ lenses 28, and then the first cylindrical mirror 30, the folding mirror 32, and the second cylindrical beam. The photosensitive member 36 is scanned by being reflected by the mirror 34 and passing through a dust-proof window (not shown).

  The half mirror 22 is a wedge prism having a trapezoidal cross-sectional shape in the main scanning direction, and reflects a part of the light beam L that has passed through the aperture 20. A lens 38 and a light amount detection sensor 40 are disposed in the traveling direction of the light beam L reflected by the half mirror 22, and the light beam L reflected by the half mirror 22 is condensed by the lens 38. It enters the light amount detection sensor 40. The light amount detection sensor 40 detects the light amount of the received light beam L, converts the light amount into a current value and outputs it to a control unit (not shown) of the light source unit 12, and the control unit of the light source unit 12 receives the input. The light amount of the light source unit 12 is controlled according to the current value.

  An SOS mirror 42 is disposed outside the effective scanning area between the folding mirror 32 and the second cylindrical mirror 34, and reflects the light beam L reflected by the folding mirror 32. An SOS lens 44 and a synchronization detection sensor 46 are disposed in the optical path of the light beam L reflected by the SOS mirror 42, and the light beam L reflected by the SOS mirror 42 is moved in the sub scanning direction by the SOS lens 44. The light is condensed and enters the synchronization detection sensor 46. The control unit of the light source unit 12 performs synchronization control based on the timing at which the synchronization detection sensor 46 receives the light beam L.

  The relationship between the lateral magnification βt in the main scanning direction and the lateral magnification βs in the sub-scanning direction of the scanning optical system 15 is expressed by the following equation (1).

  βt> βs (1).

  Here, the structure of the light source unit 12 will be described.

  As shown in FIG. 2, the light source unit 12 has a light emitting surface 50 in which a total of 32 light emitting points 48 are two-dimensionally arranged in four rows in the main scanning direction and eight rows in the sub scanning direction. The configuration is implemented in The interval between the light emitting points 48 is 28 μm in the main scanning direction and 35 μm in the sub scanning direction. That is, the relationship between the width Lt in the main scanning direction and the width Ls in the sub-scanning direction of the light emitting surface 50 is expressed by the following equation (2).

Lt <Ls (2)
The light emitting points 48 are arranged in a straight line inclined with respect to the main scanning direction and the sub-scanning direction, and can simultaneously scan the photoconductor 36 with 32 light beams L.

  As shown in FIG. 3, the light source unit 12 is mounted on the substrate 14, and the light source unit 12 is supported on the side wall 16 </ b> A by attaching the substrate 14 to the side wall 16 </ b> A of the optical housing 16. Here, as shown in FIGS. 3 to 5, three pins protrude from the periphery of the through hole 16 </ b> B formed in the side wall 16 </ b> A and abut against the surface 52 </ b> A of the package 52. Two of the three pins are a first adjustment screw 54 and a second adjustment screw 56, and the other one is a fixing pin 58 fixed to the side wall 16A.

  The first adjustment screw 54 and the second adjustment screw 56 are screwed into a sheet metal 60 attached to the inner surface of the side wall 16A, and protrude from the side wall 16A through a hole formed in the side wall 16A. The first adjustment screw 54 is disposed on one side in the sub-scanning direction (housing cover 17 side) from the light emitting surface 50, and the second adjustment screw 56 is on the other side in the sub-scanning direction (bottom surface 16C) from the light emitting surface 50. In addition, the fixing pin 58 is disposed between the first adjustment screw 54 and the second adjustment screw 56 in the sub-scanning direction. The second adjustment screw 56 is disposed on the one side in the main scanning direction (right side in FIG. 2) from the light emitting surface 50, and the fixing pin 58 is on the other side in the main scanning direction from the light emitting surface 50 (in FIG. 2). Further, the first adjustment screw 54 is disposed between the second adjustment screw 56 and the fixing pin 58 in the main scanning direction.

  That is, the first adjustment screw 54, the second adjustment screw 56, and the fixing pin 58 are disposed so as to face the periphery of the light emitting surface 50, and come into contact with three points surrounding the light emitting surface 50 of the surface 52 </ b> A of the package 52. The posture (angle) of the surface 52A of the package 52 is determined. Here, the parallelism between the surface 52A of the package 52 and the light emitting surface 50 and the flatness of the surface 52A are obtained with high accuracy. Therefore, the posture (angle) of the light emitting surface 50 can be determined with high accuracy using the surface 52A as a reference surface.

  By the way, in the present embodiment satisfying the above formulas (1) and (2), as shown in FIGS. 6A and 6B, when the light emitting surface 50 is tilted, the photosensitive surface is not affected. The light beam L in the body 36 spreads in the direction in which the magnification of the scanning optical system 15 is large, that is, in the main scanning direction, and the beam shape becomes an ellipse.

  As shown in FIG. 6A, when the light emitting surface 50 is inclined in the main scanning direction, the beam diameter of the light beam L on the photosensitive member 36 is changed from the optical axis 62 of the scanning optical system 15 to the main scanning direction. It gradually expands as you move away.

  As shown in FIG. 6B, when the light emitting surface 50 is inclined in the sub-scanning direction, the beam diameter of the light beam L on the photoreceptor 36 is changed from the optical axis 62 of the scanning optical system 15 to the sub-scanning direction. It gradually expands as you move away.

  That is, when the light emitting surface 50 is inclined in the sub-scanning direction, which is the longitudinal direction of the light emitting surface 50, the variation in the beam diameter of the light beam L on the photoconductor 36 is larger than when the light emitting surface 50 is inclined in the main scanning direction. . For this reason, when the error of the tilt adjustment with respect to the longitudinal direction of the light emitting surface 50 becomes large, the fluctuation of the beam diameter of the light beam L on the photoconductor 36 becomes large.

  Therefore, in the present embodiment, the first adjustment screw 54, the second adjustment screw 56, and the fixing pin 58 are provided so that the error in adjusting the inclination of the light emitting surface 50 is reduced with respect to the longitudinal direction of the light emitting surface 50. ing. Specifically, the angle A between the straight line L1 connecting the first adjustment screw 54 and the fixing pin 58 disposed on one side in the longitudinal direction of the light emitting surface 50 and the longitudinal direction of the light emitting surface 50, and the longitudinal direction of the light emitting surface 50 The relationship between the straight line L2 connecting the second adjustment screw 56 and the fixing pin 58 disposed on the other side and the angle B between the short side direction of the light emitting surface 50 is A> B.

  That is, when the first adjustment screw 54 is adjusted, the light emitting surface 50 is rotated about the straight line L2 connecting the second adjustment screw 56 and the fixing pin 58, so that the rotation axis L2 is shorter than the light emitting surface 50. When tilted with respect to the hand direction, the tilt adjustment of the light emitting surface 50 is performed not only with respect to the longitudinal direction but also with respect to the lateral direction. Further, when the second adjustment screw 56 is adjusted, the light emitting surface 50 is rotated with the straight line L1 connecting the first adjustment screw 54 and the fixing pin 58 as a rotation axis. When tilted with respect to the direction, the tilt adjustment of the light emitting surface 50 is performed not only with respect to the lateral direction but also with respect to the longitudinal direction.

  For this reason, when the angle B between the straight line L2 and the short side direction increases, the tilt change in the short side direction increases when the inclination adjustment of the light emitting surface 50 is performed with respect to the long side direction. Tilt adjustment cannot be performed with high accuracy. Therefore, by adjusting the angle B to be smaller than the angle A between the straight line L1 and the longitudinal direction, the adjustment error of the tilt adjustment with respect to the longitudinal direction of the light emitting surface 50 is suppressed.

  Accordingly, the attitude of the light emitting surface 50 can be adjusted with high accuracy with respect to the direction in which the variation of the beam diameter of the light beam L on the photosensitive member 36 caused by the inclination of the light emitting surface 50 is large. Defects can be effectively suppressed.

  As shown in FIG. 7, when the straight line L1 is parallel to the longitudinal direction of the light emitting surface 50 and the straight line L2 is parallel to the short direction of the issuing surface 50, the inclination adjustment of the light emitting surface 50 is performed in the longitudinal direction. It is possible to make the change in inclination in the short direction when performing with respect to the direction and the change in inclination in the longitudinal direction when adjusting the inclination of the light emitting surface 50 with respect to the short direction to be zero. The adjustment error of the tilt adjustment with respect to the longitudinal direction and the lateral direction can be eliminated.

  However, since the point where the three pins abut against the surface 52A of the package 52 is biased to one side of the light emitting surface 50, the posture of the light emitting surface 50 cannot be stabilized. For this reason, as in the present embodiment, the pins are brought into contact with the three points surrounding the light emitting surface 50 of the surface 52A of the package 52, and the relationship between the angle A and the angle B described above satisfies A> B, thereby emitting light. It is desirable to stabilize the posture of the surface 50 and to suppress an error in tilt adjustment with respect to the longitudinal direction of the light emitting surface 50.

  Next, a second embodiment will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted. In the present embodiment as well, the above expressions (1) and (2) are satisfied.

  As shown in FIGS. 8 and 9, in the optical scanning device 70, three pins protrude from the periphery of the through hole 16 </ b> B formed in the side wall 16 </ b> A and abut on the surface 52 </ b> A of the package 52. One of the three pins is an adjustment screw 72, and the other two are fixing pins 74 and 76 fixed to the side wall 16A.

  The adjusting screw 72 is screwed into a sheet metal 60 attached to the inner surface of the side wall 16A, and protrudes from the side wall 16A through a hole (not shown) formed in the side wall 16A. The adjustment screw 72 is disposed on one side of the light emitting surface 50 in the sub-scanning direction (housing cover 17 side) and in the center of the light emitting surface 50 in the main scanning direction, and the fixing pin 74 is arranged in the sub-scanning direction from the light emitting surface 50. The fixing pin 76 is disposed on the other side (the bottom surface 16C side) and on the one side in the main scanning direction (left side in FIG. 8) from the light emitting surface 50, and the fixing pin 76 is on the other side in the sub scanning direction from the light emitting surface 50 and emits light. It is disposed on the other side of the main scanning direction from the surface 50 (the right side in FIG. 8). The fixing pins 74 and 76 are arranged on a straight line substantially parallel to the main scanning direction, and the distances from the central portion of the light emitting surface 50 in the main scanning direction are equal. That is, the adjustment screw 72 and the fixing pins 74 and 76 form an isosceles triangle surrounding the light emitting surface 50.

  Here, when the adjustment screw 54 is adjusted, the light emitting surface 50 rotates about the straight line L3 connecting the fixing pins 74 and 76, and this straight line L3 is substantially parallel to the main scanning direction and emits light. The inclination of the surface 50 is adjusted only with respect to the sub-scanning direction.

  This is because, as described above, when the light emitting surface 50 is tilted in the sub-scanning direction corresponding to the longitudinal direction of the light emitting surface 50, the variation in the beam diameter of the light beam L on the photosensitive member 36 increases. By executing the inclination adjustment of the light emitting surface 50 in the direction in which the fluctuation of the light increases, the fluctuation of the beam diameter of the light beam L on the photosensitive member 36 can be reduced as a whole, and the occurrence of the image quality deterioration can be suppressed.

  In the present embodiment, the inclination of the light emitting surface 50 is adjusted with respect to the sub-scanning direction. However, the beam diameter variation of the light beam L on the photoconductor 36 caused by the inclination of the light emitting surface 50 is smaller than that in the sub-scanning direction. If the main scanning direction is larger, the inclination of the light emitting surface 50 may be adjusted with respect to the main scanning direction.

  Another reason for adjusting the inclination of the light emitting surface 50 with respect to the sub-scanning direction is that the inclination of the light emitting surface 50 with respect to the sub-scanning direction has a great influence on the density change of the image.

  As shown in FIG. 10A, when the light emitting surface 50 is inclined in the main scanning direction, the beam diameter in one scan fluctuates in a short cycle as shown in FIG. 10B. On the other hand, as shown in FIG. 11A, when the light emitting surface 50 is inclined in the sub-scanning direction, as shown in FIG. The cycle becomes longer.

  Here, an optical scanning device including light sources arranged two-dimensionally scans a plurality of light beams simultaneously. For example, when scanning at 1200 dpi with 32 light beams, the width in the sub-scanning direction of one scan is about 0.7 mm as shown in the following equation (3).

25.4 (mm / inch) /1200×32=0.68 (mm) (3)
Further, in the electrophotographic image forming apparatus, the charging potential of the photoconductor constituting the marking unit and the developability of the developing device vary depending on the energy density. Therefore, when the beam diameter on the photoconductor increases, the image density decreases. For this reason, density fluctuations according to the fluctuation period of the beam diameter in the photosensitive member occur.

  That is, as shown in FIG. 10B, when the beam diameter fluctuates in a short cycle, the density change occurs in a short cycle (eight cycles in one scan) as shown in FIG. 10C. , (3), the density change period λ1 is 0.10 mm or less, and density unevenness is hardly recognized. On the other hand, when the beam diameter fluctuates with a long period as shown in FIG. 11B, the density change with a long period (one period within one scan) as shown in FIG. 11C. Therefore, under the condition of the expression (3), the density change period λ2 is about 0.7 mm, and density unevenness appears remarkably.

  For this reason, as shown in FIGS. 8 and 9, by adjusting the inclination of the light emitting surface 50 in the sub-scanning direction, the density change cycle can be lengthened, and the occurrence of density unevenness can be suppressed.

  Since the straight line L2 serving as the rotation axis is offset from the optical axis 62, when the inclination adjustment of the light emitting surface 50 is performed, the light emitting point 48 on the optical axis 62 moves in the optical axis direction, and the imaging point becomes a light beam. Although shifted in the axial direction, this image point deviation can be corrected by moving the collimator lens 18 (see FIG. 1) or the like in the optical axis direction.

  Further, as shown in FIG. 1, a collimator lens 18 and the like are mounted in the vicinity of the light source unit 12, and a space for adjusting the adjustment screw 72 is limited. Therefore, in the present embodiment, as shown in FIG. 9, the adjustment screw 72 is disposed on the housing cover 17 side in the sub-scanning direction, that is, on the open side of the optical housing 16, and the fixing pins 74 and 76 are arranged on the bottom surface in the sub-scanning direction. By disposing on the 16C side, the adjustment screw 72 is provided away from the bottom surface 16C of the optical housing 16, and the degree of freedom of access during adjustment is ensured.

  Further, by making the distance of the fixing pins 74 and 76 in the main scanning direction the longest within a range not deviating from the surface 52A of the package 52, the inclination of the light emitting surface 50 which is not adjusted can be suppressed to the maximum.

  Next, a third embodiment will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st, 2nd embodiment, and description is abbreviate | omitted.

  As shown in FIG. 12, in the optical scanning device 80, the first adjustment screw 54 and the second adjustment screw 56 are screwed into the package 52 of the light source unit 12, and fixing pins 58 (not shown) are fixed. Is in contact with the side wall 16A. The surface of the side wall 16A with which the first adjustment screw 54, the second adjustment screw 56, and the fixing pin 58 come into contact has high flatness, and the posture of the light emitting surface 50 can be determined with high accuracy.

  Here, the substrate 14 has through holes 14A and 14B through which the first adjustment screw 54 and the second adjustment screw 56 pass, and the first adjustment is made from the back side of the substrate 14, that is, from the outside of the optical scanning device 80. The screw 54 and the second adjusting screw 56 can be adjusted. Therefore, the adjustment work is easy, and the image quality can be adjusted by adjusting the inclination of the light source unit 12 in a state where the optical scanning device 80 is mounted on the image forming apparatus.

It is a perspective view which shows the optical scanning device of 1st Embodiment. It is a front view which shows the adjustment mechanism of the light source part of the optical scanning device of 1st Embodiment. It is a top view which shows the optical scanning device of 1st Embodiment. FIG. 4 is a 4-4 sectional view of the optical scanning device shown in FIG. 3. It is a perspective view which shows the light source support part of the optical scanning device of 1st Embodiment. FIGS. 4A and 4B are diagrams showing fluctuations in the beam diameter of the light beam on the photosensitive member caused by the inclination of the light emitting surface. FIG. 5A shows the case where the light emitting surface is inclined with respect to the main scanning direction, and FIG. The case where it inclines with respect to the direction is shown. It is a front view which shows the modification of the adjustment mechanism of the light source part of the optical scanning device of 1st Embodiment. It is a front view which shows the adjustment mechanism of the light source part of the optical scanning device of 2nd Embodiment. It is a perspective view which shows the light source support part of the optical scanning device of 2nd Embodiment. When the light emitting surface is inclined with respect to the main scanning direction, (A) is a diagram showing the fluctuation of the beam diameter of the light beam on the photoconductor, and (B) is the distribution state of the light beam on the photoconductor. FIG. 4C is a graph showing changes in image density. When the light emitting surface is tilted with respect to the sub-scanning direction, (A) is a diagram showing the variation of the beam diameter of the light beam on the photoconductor, and (B) is the distribution state of the light beam on the photoconductor. FIG. 4C is a graph showing changes in image density. It is sectional drawing which shows the optical scanning device of 3rd Embodiment. (A) is a figure which shows the relationship between the horizontal magnification of a scanning optical system, and image formation, (B) is the horizontal magnification of a scanning optical system, and image formation when a light emission surface shift | deviates to an optical axis direction. It is a figure which shows a relationship. (A) is a figure which shows the relationship between the lateral magnification of a scanning optical system and image formation when a light emitting surface inclines, (B) is a figure which shows a light emitting surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical scanning device 12 Light source part 15 Scanning optical system 16 Optical housing 16A Side wall (light source support surface)
16C bottom surface 17 housing 36 photoconductor (scanned surface)
48 Light emitting point 50 Light emitting surface 52A Surface (reference surface)
54 First adjustment screw (contact point, adjustment contact point, adjustment screw)
56 Second adjustment screw (contact point, adjustment contact point, adjustment screw)
58 Fixed pin (contact point, fixed contact point)
70 Optical scanning device 72 Adjustment screw (contact point, adjustment contact point, adjustment screw)
74 Fixing pin (contact point, fixed contact point)
76 Fixing pin (contact point, fixed contact point)
80 Optical scanning device L Light beam L1 Straight line L2 Straight line

Claims (9)

A light source unit for emitting a plurality of light beams from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged;
A scanning optical system that deflects and scans a surface to be scanned with a plurality of light beams emitted from the light source unit,
Projecting from a light source support surface on which the light source unit is supported, contacting three points surrounding the light emitting surface of the light source unit, and comprising three contact points that determine the posture of the light emitting surface;
The optical scanning device according to claim 1, wherein at least one of the three contact points is an adjustment contact point capable of adjusting an amount of protrusion from the light source support surface.   2. The optical scanning device according to claim 1, wherein the light source unit has a reference surface that is substantially parallel to the light emitting surface and contacts the three contact points.   The optical scanning device according to claim 1, wherein the adjustment contact point is an adjustment screw that passes through the light source support surface and is adjusted from the inside of the device. A light source unit for emitting a plurality of light beams from a light emitting surface in which a plurality of light emitting points are two-dimensionally arranged;
A scanning optical system that deflects and scans a surface to be scanned with a plurality of light beams emitted from the light source unit,
Projecting from the three points surrounding the light emitting surface of the light source unit to contact the light source support surface on which the light source unit is supported, and comprising three contact points that determine the posture of the light emitting surface;
The optical scanning device according to claim 1, wherein at least one of the three contact points is an adjustment contact point capable of adjusting a protruding amount from the light source unit.   5. The light according to claim 1, wherein beam diameters of a plurality of light beams on the surface to be scanned are adjusted by adjusting an attitude of the light emitting surface by the adjustment contact point. Scanning device. Two of the three contact points are set as the adjustment contact points, which are disposed on one side and the other side in the longitudinal direction of the light emitting surface, and the other one contact point is the light source support surface or As a fixed contact point fixed to the light source unit, disposed on the other side in the longitudinal direction of the light emitting surface,
An angle A between a straight line connecting the adjustment contact point and the fixed contact point disposed on one side in the longitudinal direction of the light emitting surface and the longitudinal direction of the light emitting surface and the other side in the longitudinal direction of the light emitting surface. 6. The relationship between the straight line connecting the adjustment contact point and the fixed contact point provided and the angle B between the short side direction of the light emitting surface is set as A> B. The optical scanning device according to Item. One of the three contact points is set as the adjustment contact point,
The other two contact points are in the main scanning direction or the sub-scanning direction with respect to the larger variation in the beam diameter of the plurality of light beams on the scanned surface, which is caused by the inclination of the light emitting surface. 6. The optical scanning device according to claim 1, wherein the optical scanning device is disposed on a substantially perpendicular straight line. One of the three contact points is set as the adjustment contact point,
6. The optical scanning device according to claim 1, wherein the other two contact points are arranged on a straight line substantially parallel to the main scanning direction. An optical housing that supports the scanning optical system on a bottom surface, and the light source support surface is provided on a side wall; and a housing cover that covers the optical housing,
9. The adjustment contact point is disposed on the housing cover side in the sub-scanning direction, and the other contact point is disposed on the bottom surface side in the sub-scanning direction. The optical scanning device according to 1.

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