JP2006201274A - Optical scanning device and image forming apparatus to which the same is applied - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent with simple constitution the shift in a scanning position with respect to a sub scanning direction of an optical beam, due to the rise in the temperature of an optical scanning device. <P>SOLUTION: When a device chassis 12 is expanded by the rise in the temperature of the optical scanning device 10, the optical beam emitted toward a photoreceptor 22 is shifted upwardly with respect to the sub scanning direction, due to the distortion between a bottom plate 12A and a side plate 12B of the device chassis 12 or the variation in attachment alignment by the thermal expansion of an optical component. Because it is constituted so that a hemispherical protrusion 24 travels obliquely to the optical beam emission direction, along a slant surface 34 descending downwardly with respect to the sub scanning direction, by the stretch in the emission direction by the thermal expansion of the device chassis 12, the upward shift in the beam position with respect to the sub scanning direction can be downwardly corrected with respect to the sub scanning direction. Accordingly, only utilizing the slant surface 34 formed on a main body frame 32, the shift in the beam position with respect to the sub scanning direction is prevented with a simple mechanism. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device that prevents deviation of a scanning position of a light beam due to a temperature rise, and an image forming apparatus to which the optical scanning device is applied.

  In a general optical scanning device applied to an image forming apparatus, a light beam emitted from a light source is incident on a rotary polygon mirror, and the incident light beam is emitted to a photosensitive member and scanned in the main scanning direction. The light beam emitted to the photoconductor is imaged on the photoconductor by the fθ lens.

  At this time, the temperature in the image forming apparatus gradually rises due to the heat generated from the scanner motor and the light source driving circuit for driving the rotary polygon mirror, and other heat generated in the image forming apparatus, and the optical scanning is performed. The temperature of the device also rises.

  At this time, the optical components such as the lens of the optical scanning device and the device casing are thermally expanded, so that the scanning position of the optical beam fluctuates, resulting in image quality degradation, and the optical beam is blocked by other components. Cause problems such as failure to reach the photoconductor.

  In order to solve this problem, in Patent Document 1, an adjustment mechanism is provided, and the optical scanning device is rotated by the thermal expansion of the adjustment mechanism to prevent fluctuations in the scanning position of the light beam.

  However, this technique has a problem in that the number of parts is increased by providing a new adjustment mechanism, the optical scanning device is increased, and the cost is increased.

  Further, in Patent Document 2, the abutting portion between the bottom plate and the peripheral wall of the casing of the optical scanning device is used as an inclined surface, and the inclined surface is used to deform the device casing to the outside and to the inside of the bottom plate when the apparatus casing is thermally expanded. This prevents the displacement of the scanning position of the light beam.

  However, there is a problem in that the apparatus housing is locally deformed due to the influence of holes and ribs provided in the bottom plate, and the mounting accuracy of the optical components in the housing is deteriorated.

In Patent Document 3, the tilt adjustment in the scanning direction is performed by the slope, but this technique is intended to adjust the height in the scanning direction and cannot prevent the light beam sub-scanning position shift when the temperature rises. In addition, the optical scanning device is supported by the frame on the image forming apparatus side at four points, and when the optical scanning device casing is thermally expanded locally, it is supported at three points, resulting in an unstable posture. There is a problem that.
JP 2000-267033 A JP 2001-228426 A Japanese Utility Model Publication No. 61-201011

  In view of the above facts, an object of the present invention is to prevent the deviation of the scanning position of the light beam in the sub-scanning direction due to the temperature rise of the optical scanning device with a simple configuration.

  According to a first aspect of the present invention, an apparatus housing supported by a plurality of support portions on a main body frame provided in the image forming apparatus, and a light source that is disposed in the apparatus housing and emits a light beam, A rotating polygon mirror that enters the light beam emitted from the light source, emits the incident light beam to the photosensitive member, and scans the light beam in the main scanning direction; and the light beam emitted from the rotating polygon mirror. An optical scanning device comprising an optical element that forms an image on a photosensitive member, wherein the plurality of support portions include a first support portion provided at a lower portion of the device casing and a lower portion of the device casing. And two second support portions arranged along the surface to be scanned of the photoconductor, and the first support portion can be skewed in the main body frame and directed in the light beam emitting direction. And an inclined surface having an angle in the sub-scanning direction is formed. The body is rotatable about a line connecting the two second support parts, and the first support part inclines the inclined surface in a direction opposite to the direction of deviation of the light beam due to temperature rise. The light beam emission direction front side is inclined.

  In this optical scanning device, a light beam emitted from a light source is incident on a rotary polygon mirror, and the incident light beam is emitted to the photosensitive member and scanned in the main scanning direction. The light beam emitted to the photoconductor is imaged on the photoconductor by an optical element.

  The apparatus housing of the optical scanning device has one first support portion provided at the lower portion of the apparatus housing and two second supports arranged at the lower portion of the apparatus housing along the surface to be scanned of the photosensitive member. The main body frame provided in the image forming apparatus is supported at three points. In the main body frame, the first support portion can be skewed, and an inclined surface having an angle in the sub-scanning direction toward the light beam emitting direction is formed.

  In addition, the apparatus housing is rotatable about a line connecting the two second support parts, and the first support part obliquely moves the inclined surface, so that the light beam is emitted in a direction opposite to the light beam shift direction due to temperature rise. Tilt the front side of the beam emission direction.

  Here, when the apparatus casing expands due to the temperature rise of the optical scanning apparatus, the apparatus casing is deformed and the mounting alignment of optical components such as an optical element and a rotary polygon mirror is changed. For this reason, the light beam emitted to the photosensitive member is shifted to one side in the sub-scanning direction.

  However, in the above configuration, the apparatus housing can rotate about the line connecting the two second support portions as the rotation axis. The first support portion skews the inclined surface having an angle in the scanning direction. When the first support section is inclined on the inclined surface, the apparatus housing tilts the front side of the light beam emission direction in the direction opposite to the direction of deviation of the light beam due to temperature rise, and thus corrects the deviation of the beam position in the sub-scanning direction. be able to. Thus, since only the inclined surface formed on the main body frame is used, deviation of the beam position in the sub-scanning direction can be prevented with a simple mechanism.

  In addition, since the apparatus housing is supported at three points and can be rotated about the line connecting the two second support portions as the rotation axis, even if the device housing is locally deformed, it is supported at three points. Is maintained, and the posture of the apparatus housing is stabilized.

  According to a second aspect of the present invention, in the configuration of the first aspect, the first support portion is provided on the front side of the device housing in the light beam emitting direction, and the second support portion is disposed on the device housing. It is provided on the rear side of the body in the light beam emitting direction.

  According to this configuration, since the second support portion is provided on the rear side in the light beam emitting direction of the apparatus casing, the apparatus casing is rotated about the rear side in the light beam emitting direction.

  Then, the first support portion provided on the front side of the light emitting direction of the device casing obliquely moves the inclined surface having an angle in the sub-scanning direction toward the light beam emitting direction, so that the device housing is The front side of the light beam emission direction is tilted in the direction opposite to the light beam deviation direction due to the temperature rise of the optical scanning device, and the deviation of the beam position in the sub-scanning direction can be corrected.

  In the invention according to claim 3 of the present invention, in the configuration of claim 2, the inclination angle of the inclined surface is θ, the temperature rise of the device housing is ΔT, and the line connecting the two second support portions is The shortest distance to the first support portion is L1, the shortest distance from the first support portion to the surface to be scanned on the photoconductor is L2, and the amount of deviation in the sub-scanning direction of the beam position on the surface to be scanned on the photoconductor due to temperature rise Is y, and the linear expansion coefficient of the device casing is α, θ = atan (y / ((L1 + L2) * α * ΔT)).

  According to this configuration, since the inclination of the inclined surface is determined based on the amount of deviation of the beam position in the sub-scanning direction due to the temperature rise of the optical scanning device, the deviation of the beam position in the sub-scanning direction can be reliably performed. Can be prevented.

  According to a fourth aspect of the present invention, in the configuration of the first aspect, the first support portion is provided on the rear side of the device housing in the light beam emitting direction, and the second support portion is disposed on the device housing. It is provided on the front side of the body in the light beam emitting direction.

  According to this configuration, since the second support portion is provided on the front side of the apparatus housing in the light beam emission direction, the apparatus housing rotates around the rotation axis on the front side of the light beam emission direction.

  Then, the first support portion provided on the rear side of the device housing in the light beam emitting direction skews an inclined surface having an angle in the sub-scanning direction toward the light beam emitting direction. The front side of the light beam emission direction is tilted in the direction opposite to the light beam deviation direction due to the temperature rise of the optical scanning device, and the deviation of the beam position in the sub-scanning direction can be corrected.

  In the invention according to claim 5 of the present invention, in the configuration of claim 4, the inclination angle of the inclined surface is θ, the temperature rise of the apparatus housing is ΔT, and the line connecting the two second support portions is The shortest distance to the first support portion is L1, the shortest distance from the first support portion to the surface to be scanned on the photoconductor is L2, and the amount of deviation in the sub-scanning direction of the beam position on the surface to be scanned on the photoconductor due to temperature rise Is y, and the linear expansion coefficient of the apparatus housing is α, θ = atan (y / ((L2−L1) * α * ΔT)).

  According to this configuration, since the inclination of the inclined surface is determined based on the amount of deviation of the beam position in the sub-scanning direction due to the temperature rise of the optical scanning device, the deviation of the beam position in the sub-scanning direction can be reliably performed. Can be prevented.

  According to a sixth aspect of the present invention, in the configuration according to any one of the first to fifth aspects, the amount of change in the inclination angle of the inclined surface is determined in the sub-scanning direction on the surface to be scanned on the photosensitive member due to a temperature rise. It is characterized in that it is matched with the beam position deviation amount.

  Usually, the relationship between the temperature rise amount of the optical scanning device and the beam position deviation amount of the light beam is not constant, and the “temperature rise” inherent to the optical scanning device depends on factors such as the temperature region, the structure of the housing, and the arrangement of optical components. Draw an “amount-beam position deviation amount curve”.

  In the above configuration, by adjusting the amount of change in the inclination angle of the inclined surface to the amount of beam position deviation in the sub-scanning direction due to the temperature rise of the optical scanning device, it is possible to prevent the beam position deviation in the sub-scanning direction more reliably. .

  In the invention which concerns on Claim 7 of this invention, in the structure of any one of Claims 1-6, the said 2nd 2nd support part is a hemispherical protrusion, The one is the said main body flame | frame. The other is engaged with the formed recess, and the other is characterized in that a groove formed in the main body frame can be moved along the main scanning direction.

  According to this configuration, by moving one of the two second support portions along the groove formed along the main scanning direction, the extension of the apparatus housing in the main scanning direction due to the temperature rise of the optical scanning apparatus is released. And the posture of the apparatus housing is stabilized.

  According to an eighth aspect of the present invention, in an image forming apparatus including a plurality of optical scanning devices, any one of the optical scanning devices according to the first to seventh aspects is applied to each of the plurality of optical scanning devices. It is characterized by.

  If the temperature distribution in the image forming apparatus is not uniform, the beam position deviation amount of the light beam of each optical scanning device varies. In the above configuration, since any one of the optical scanning devices according to claims 1 to 7 is applied to each of the plurality of optical scanning devices, there is a case where temperature distribution is uneven in the image forming apparatus or each optical scanning device. Even if the heat generation amount of the apparatus is different, it is possible to prevent the deviation of the beam position of the light beam.

  Since the present invention has the above-described configuration, it is possible to prevent the shift of the scanning position of the light beam in the sub-scanning direction due to the temperature rise of the optical scanning device with a simple configuration.

(First embodiment)
1st Embodiment which concerns on the optical scanning device of this invention is described based on FIGS.

  FIG. 1 shows an outline of an optical scanning device arranged inside the image forming apparatus.

  The optical scanning device 10 includes an apparatus housing 12, and a light source 14 is disposed in the apparatus housing 12, and the light beam B is directed toward the collimator lens 16 positioned coaxially with the light source 14 by the light source 14. Irradiated.

  The light beam B emitted from the light source 14 is converted into parallel rays by the collimator lens 16 and is incident on a polygon mirror (rotating polygon mirror) 18 that is rotated at a high speed by a scanner motor (not shown). The incident light beam B is a photoconductor. 22 is deflected and scanned. The light beam B emitted from the polygon mirror 18 is subjected to scanning speed correction by an fθ lens (optical element) 20, and a latent image corresponding to an image signal is formed on a photoconductor 22 that is an image carrier.

  As shown in FIG. 2, the device housing 12 of the optical scanning device 10 is formed in a box shape with a bottom plate 12A and a side plate 12B erected on the outer periphery thereof, and the bottom plate (lower portion) 12A has three hemispheres. The protrusions (hemispherical protrusions) 24, 26, and 28 are formed.

  The hemispherical protrusion (first support portion) 24 is provided at the center of the apparatus housing 12 on the front side in the light beam emission direction (direction C in FIG. 2). The hemispherical protrusion (second support portion) 26 is formed on one of the flanges 30 protruding in the lateral direction (D direction in FIG. 2) on the rear side of the light beam emission direction of the apparatus housing 12, and the hemispherical protrusion (second The support portion 28 is formed on the other bottom plate 12A of the flange 30 projecting in the lateral direction. The hemispherical protrusions 26 and the hemispherical protrusions 28 are arranged along the surface to be scanned of the photosensitive member 22 (parallel to the surface to be scanned).

  On the other hand, in the main body frame 32 provided on the image forming apparatus side, as shown in FIG. 3, a support base 36 with an inclined surface 34, a support base 40 with a hemispherical recess 38, and a groove 42. And a support base 44 formed along the scanning direction.

  A leaf spring 46 for pressing the device housing 12 is screwed to the block 50 in the vicinity of the support base 44 and the support base 40.

  The hemispherical protrusion 24 of the apparatus housing 12 is supported by being in contact with the inclined surface 34 of the main body frame 32, and the hemispherical protrusion 28 of the apparatus housing 12 is supported by being engaged with the recess 38 of the main body frame 32. The hemispherical protrusion 26 of the body 12 is supported by being engaged with the groove 42 of the main body frame 32.

  As shown in FIGS. 4A and 4B, the rear side of the device housing 12 in the light beam emitting direction is moved to the main body frame 32 side by a leaf spring 46 in which each of the flanges 30 is fixed to the upper portion of the block 50. It is pressed. Further, the plate piece 47 that protrudes forward on the front side in the light beam emitting direction is connected to the main body frame 32 by a spring 48, and the front side of the device housing 12 in the light beam emitting direction on the main body frame 32 by the elastic force of the spring 48. It is urged to the side.

  Thereby, the hemispherical protrusion 24 can be skewed without floating on the inclined surface 34, and the hemispherical protrusion 26 can move the groove 42 in the scanning direction (D direction in FIG. 4B). The hemispherical projection 28 remains in the concave portion 38 and its position does not change.

  Further, the apparatus housing 12 can be rotated about a line connecting the hemispherical protrusions 26 and the hemispherical protrusions 28 (in FIG. 4A, it can be rotated in the A direction). That is, the emitted light beam B can move in the sub-scanning direction (vertical direction) on the surface to be scanned of the photosensitive member 22.

  In addition, the inclined surface 34 is an inclined surface that goes down in the sub-scanning direction toward the light beam emission direction, and the inclination angle θ is as shown in FIGS. 5 (A) and 5 (B). The temperature rise is ΔT, the shortest distance from the line connecting the hemispherical protrusion 26 and the hemispherical protrusion 28 to the hemispherical protrusion 24 is L1, the shortest distance from the hemispherical protrusion 24 to the scanned surface on the photoreceptor 22 is L2, and the light When the amount of deviation in the sub-scanning direction of the beam position on the surface to be scanned on the photosensitive member 22 due to the temperature rise of the scanning device 10 is y and the linear expansion coefficient of the device housing 12 is α, θ = atan (y / ( (L1 + L2) * α * ΔT)).

  The beam position deviation y is deformed, for example, in a direction in which the side plate 12B standing on the outer periphery of the bottom plate 12A of the apparatus housing 12 spreads outward, and the bottom plate 12A is also curved and deformed accordingly (FIG. 5A). The two-dot chain line portion shows the state after the device housing 12 is deformed), and the mounting alignment of optical components such as the fθ lens 20 and the polygon mirror 18 changes.

  In addition, as described below, the support base 36 provided with the inclined surface 34 may be provided not on the front side in the light beam emission direction but on the rear side in the light beam emission direction.

  That is, as shown in FIGS. 6A and 6B, the hemispherical protrusion 26 and the hemispherical protrusion 28 are provided on a flange 30 that protrudes laterally on the front side of the light emitting direction of the device housing 12. Yes. Further, the hemispherical protrusion 24 is provided at the center of the apparatus housing 12 on the rear side in the light beam emitting direction.

  Correspondingly, the support base 44 in which the grooves 42 are formed along the scanning direction and the support base 40 in which the hemispherical recesses 38 are formed are provided on the front side of the main body frame 32 in the light beam emission direction, and are inclined surfaces. The support base 36 formed with 34 is provided on the rear side of the main body frame 32 in the light beam emitting direction. The hemispherical protrusion 24 of the device housing 12 is supported by being in contact with the inclined surface 34, and the hemispherical protrusion 28 of the device housing 12 is supported by being engaged with the recess 38, and the hemisphere of the device housing 12 is supported. The protrusion 26 is supported by being engaged with the groove 42.

  The front side of the device housing 12 in the light beam emitting direction is pressed toward the main body frame 32 by a leaf spring 46 in which each of the flanges 30 is fixed to the upper portion of the block 50. Further, the plate piece 47 protruding rearward on the rear side in the light beam emitting direction is connected to the main body frame 32 by a spring 48, and the main body frame 32 is connected to the rear side in the light beam emitting direction of the apparatus housing 12 by the elastic force of the spring 48. It is urged to the side.

  Accordingly, the hemispherical protrusion 24 can be inclined without floating on the inclined surface 34, and the hemispherical protrusion 26 can move the groove 42 in the scanning direction (D direction in FIG. 6B). The hemispherical projection 28 remains in the concave portion 38 and its position does not change.

  Further, the apparatus housing 12 can be rotated about a line connecting the hemispherical protrusion 26 and the hemispherical protrusion 28 (in FIG. 6A, the apparatus housing 12 is rotatable in the A direction). That is, the emitted light beam B can move in the sub-scanning direction (vertical direction) on the surface to be scanned of the photosensitive member 22.

  In addition, the inclined surface 34 is an inclined surface that descends downward in the sub-scanning direction toward the light beam emission direction, and the inclination angle θ causes the temperature rise of the apparatus housing 12 to be Δ as shown in FIG. T, the shortest distance from the line connecting the hemispherical protrusion 26 and the hemispherical protrusion 28 to the hemispherical protrusion 24 is L1, the shortest distance from the hemispherical protrusion 24 to the surface to be scanned on the photoconductor 22 is L2, and the optical scanning device 10 When y is the amount of deviation of the beam position in the sub-scanning direction on the surface to be scanned on the photoreceptor 22 due to temperature rise, and α is the linear expansion coefficient of the apparatus housing 12, θ = atan (y / ((L2-L1 ) * Α * ΔT)).

  Next, the operation of the first embodiment will be described.

  When the optical scanning device 10 is operated, the temperature of the optical scanning device 10 rises due to heat generated from the scanner motor of the polygon mirror 18 and the drive circuit of the light source 14.

  When the temperature of the optical scanning device 10 rises, the device housing 12 extends in the emission direction due to thermal expansion. At this time, since the apparatus housing 12 can be rotated with a line connecting the hemispherical protrusion 26 and the hemispherical protrusion 28 as a rotation axis, the hemispherical protrusion 24 inclines the inclined surface 34 forward in the light beam emitting direction and inclines. It goes down along the surface 34 in the sub-scanning direction. Further, in the configuration in which the inclined surface 34 is formed on the rear side in the light beam emitting direction, the hemispherical protrusion 24 obliquely tilts the inclined surface 34 rearward in the light beam emitting direction and moves upward along the inclined surface 34 in the sub-scanning direction. climb.

  For this reason, the front side of the light beam emission direction of the optical scanning device 10 is inclined downward in the sub-scanning direction, and the emission end surface of the optical scanning device 10 is directed downward in the sub-scanning direction. Correction can be made downward in the scanning direction. As described above, since only the inclined surface 34 formed on the main body frame 32 is used, it is possible to prevent deviation of the beam position in the sub-scanning direction with a simple mechanism.

  The apparatus housing 12 is supported at three points of the hemispherical protrusions 24, 26, and 28, and can rotate about a line connecting the hemispherical protrusion 26 and the hemispherical protrusion 28. Even if it is locally deformed, support at three points is maintained, and the posture of the apparatus housing 12 is stabilized.

  Furthermore, since the hemispherical protrusion 26 moves in the scanning direction in the groove 42, the expansion in the scanning direction due to the thermal expansion of the apparatus housing can be released, and the attitude of the apparatus housing is stabilized.

  As described above, in this embodiment, the light beam position shift due to the temperature rise of the entire optical scanning device 10 including the distortion between the bottom plate 12A and the side plate 12B of the apparatus housing 12 and the mounting alignment due to the thermal expansion of the optical components. Is displaced in the direction opposite to the direction of deviation, thereby preventing the deviation of the light beam position on the photosensitive member 22 by moving the apparatus housing 12 of the optical scanning device 10.

  In the first embodiment, the inclined surface 34 is formed on the assumption that the light beam is shifted upward. When the inclined surface 34 is formed, first, the hemisphere is not on the inclined surface 34 but on the horizontal plane. A temperature characteristic test is performed with the projections 24 placed thereon, and at that time, data on the beam position deviation of the light beam that is peculiar to each apparatus is obtained. Based on this, the inclination direction of the inclined surface 34 having an angle in the sub-scanning direction toward the light beam emission direction is determined, and the beam position deviation of the light beam is prevented.

  Therefore, an apparatus that has been confirmed to cause a beam position shift not in the sub-scanning direction but in the sub-scanning direction lower than in the sub-scanning direction is configured as follows.

  That is, as shown in FIG. 7A, when the inclined surface 34 is formed in front of the light beam emitting direction, the inclined surface 34 that rises upward in the sub-scanning direction toward the light beam emitting direction. Form.

  Further, as shown in FIG. 7B, even when the inclined surface 34 is formed behind the light beam emitting direction, the inclined surface 34 that rises upward in the sub-scanning direction toward the light beam emitting direction. Form.

  As shown in FIG. 7A, in the configuration in which the inclined surface 34 is formed on the rear side in the light beam emission direction, the temperature of the optical scanning device 10 rises, and the device housing 12 extends in the emission direction due to thermal expansion. Then, the hemispherical protrusion 24 skews the inclined surface 34 forward in the light beam emitting direction and rises upward along the inclined surface 34 in the sub-scanning direction.

  Further, as shown in FIG. 7B, in the configuration in which the inclined surface 34 is formed on the rear side in the light beam emitting direction, the temperature of the optical scanning device 10 rises, and the device housing 12 emits in the emitting direction due to thermal expansion. The hemispherical protrusion 24 skews the inclined surface 34 backward in the light beam emission direction and descends downward along the inclined surface 34 in the sub-scanning direction.

For this reason, the front side of the light beam emission direction of the optical scanning device 10 is inclined upward in the sub-scanning direction, and the emission end face of the optical scanning device 10 is directed upward in the sub-scanning direction. Correction can be made upward in the scanning direction.
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the part same as 1st Embodiment, description is abbreviate | omitted, and only a different part from 1st Embodiment is demonstrated.

  In the first embodiment, the inclination angle of the inclined surface 34 is obtained by θ = atan (y / ((L1 + L2) * α * ΔT)) and is a constant angle.

  That is, as shown in FIG. 8A, when the relationship between the temperature rise amount and the beam position deviation amount of the light beam is constant, as shown in FIG. 8D, the inclination is inclined at a constant angle. Even on the surface 34, the positional deviation of the light beam can be corrected.

  However, the relationship between the amount of temperature rise and the amount of positional deviation of the light beam is usually not constant. For example, the relationship between the temperature region, the structure of the apparatus housing 12, the arrangement of optical components, and the like are shown in FIGS. As shown, a “temperature rise amount-light beam position deviation amount curve” unique to the optical scanning device is drawn.

  As shown in FIG. 8B, when the amount of deviation is small with respect to the temperature change, as shown in FIG. 8E, the angle change amount that can form an inclined surface 52 that is bulged upward and curved is shown. As shown in FIG. 8C, when the amount of deviation with respect to the temperature change is large, as shown in FIG. 8F, the angle change amount forms an inclined surface 54 that bulges downward and curves.

As described above, if the inclination θ of the inclined surface 34 is matched with the beam position deviation amount in the sub-scanning direction due to the temperature rise, corresponding to the “temperature rise amount-light beam position deviation amount curve” inherent to the optical scanning device, It is possible to prevent the beam position deviation in the sub-scanning direction precisely.
(Third embodiment)
Next, a third embodiment in which the optical scanning device of the first embodiment is applied to a color image forming apparatus will be described with reference to FIG.

  Here, the present invention is applied to a so-called tandem type image forming apparatus 60 that includes a plurality of independent image forming units, continuously transfers the formed development onto a single transfer medium, and forms a full color image in one cycle.

  In this embodiment, as in the first embodiment, three hemispherical protrusions (hemispherical protrusions) are formed on the bottom plate 12A of each of the four optical scanning devices 61 to 64 for each of the colors Y, M, C, and K. ) 24, 26, and 28, and the hemispherical protrusion 24 is in contact with and supported by an inclined surface 34 having an angle in the sub-scanning direction toward the light beam emitting direction, and the hemispherical protrusion 28 is engaged with the recess 38. The hemispherical protrusions 26 were engaged with and supported by the grooves 42.

  In the tandem image forming apparatus, since the light beams reach the photoconductors 71 to 74 through independent optical systems from the light scanning devices 61 to 64 serving as exposure sources for the colors Y, M, C, and K, the image forming apparatus. In this embodiment, there is a problem that the amount of misalignment of the light beam in each color varies due to non-uniform temperature distribution in 60 and color misregistration occurs in the superimposed color image. In this embodiment, however, Y, M, C , K for each color, the optical scanning devices 61 to 64 of the first embodiment are applied. Therefore, when there is non-uniform temperature distribution in the color image forming device 60 or for each color, the optical scanning devices 61 to 64 are used. This is particularly effective because the light beam position does not shift even if the amount of heat generation is different.

  The present invention is not limited to the embodiment described above, and various forms are possible.

FIG. 1 is a schematic diagram of an optical scanning device according to the first embodiment of the present invention. FIG. 2 is a diagram of the optical scanning device according to the first embodiment viewed from below. FIG. 3 is a view showing the main body frame according to the first embodiment. FIG. 4 is a plan view of the optical scanning device according to the first embodiment. FIG. 5 is a plan view of the optical scanning device according to the first embodiment. FIG. 6 is a plan view showing a modification of the optical scanning device according to the first embodiment. FIG. 7 is a plan view showing a modification of the optical scanning device according to the first embodiment. FIG. 8 is a diagram illustrating the inclination of the inclined surface according to the second embodiment. FIG. 9 is a diagram illustrating an image forming apparatus according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical scanning device 12 Apparatus housing 14 Light source 18 Polygon mirror (rotating polygon mirror)
20 fθ lens (optical element)
24 Hemispherical protrusion (first support part)
26 Hemispherical protrusion (second support part)
28 Hemispherical protrusion (second support part)
32 body frame 34 inclined surface 38 recess 42 groove 60 image forming apparatus

Claims (8)

An apparatus housing supported by a plurality of support portions on a main body frame provided in the image forming apparatus;
A light source that is disposed within the device housing and that emits a light beam;
A rotating polygon mirror that enters the light beam emitted from the light source, emits the incident light beam to the photosensitive member, and scans the light beam in the main scanning direction;
An optical element that forms an image of the light beam emitted from the rotary polygon mirror on the photosensitive member;
In an optical scanning device comprising:
The plurality of support portions include one first support portion provided at a lower portion of the apparatus housing, and two second supports arranged at a lower portion of the apparatus housing along a scanned surface of the photoconductor. Part, and
In the main body frame, the first support portion can be skewed, and an inclined surface having an angle in the sub-scanning direction toward the light beam emission direction is formed.
The apparatus housing is rotatable about a line connecting the two second support parts, and the first support part skews the inclined surface, thereby causing a deviation direction of the light beam due to temperature rise. An optical scanning device characterized by tilting the front side of the light beam emitting direction in the opposite direction. The first support portion is provided on the front side of the device housing in the light beam emitting direction,
The optical scanning device according to claim 1, wherein the second support portion is provided on the rear side of the device housing in the light beam emitting direction.   The inclination angle of the inclined surface is θ, the temperature rise of the apparatus housing is ΔT, the shortest distance from the line connecting the two second support parts to the first support part is L1, and the first support part is exposed to light. When the shortest distance to the body scanning surface is L2, the deviation of the beam position on the photosensitive body scanning surface due to temperature rise in the sub-scanning direction is y, and the linear expansion coefficient of the apparatus housing is α, The optical scanning device according to claim 2, wherein θ = atan (y / ((L1 + L2) * α * ΔT)). The first support portion is provided on the rear side of the device housing in the light beam emission direction,
The optical scanning device according to claim 1, wherein the second support portion is provided on the front side of the device housing in the light beam emitting direction.   The inclination angle of the inclined surface is θ, the temperature rise of the apparatus housing is ΔT, the shortest distance from the line connecting the two second support parts to the first support part is L1, and the first support part is exposed to light. When the shortest distance to the body scanning surface is L2, the deviation of the beam position on the photosensitive body scanning surface due to temperature rise in the sub-scanning direction is y, and the linear expansion coefficient of the apparatus housing is α, The optical scanning device according to claim 4, wherein θ = atan (y / ((L2−L1) * α * ΔT)).   The amount of change in the inclination angle of the inclined surface is matched with the amount of beam position deviation in the sub-scanning direction on the surface to be scanned on the photosensitive member due to a temperature rise. Optical scanning device. The two second support parts are hemispherical protrusions,
7. One of them is engaged with a recess formed in the main body frame, and the other is movable in a groove formed in the main body frame along the main scanning direction. The optical scanning device according to any one of the above. In an image forming apparatus including a plurality of optical scanning devices,
An image forming apparatus, wherein one of the optical scanning devices according to claim 1 is applied to each of the plurality of optical scanning devices.

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