JP5853677B2 - Scanning optical device - Google Patents

Description

  The present invention relates to a scanning optical device.

  In the scanning optical device, in order to improve the image quality of the image formed on the photosensitive member, it is very important to suppress the change in the optical performance due to the expansion or contraction of the scanning optical element based on the temperature change. However, since the scanning optical element is elongated and has a higher linear expansion coefficient than a housing such as a housing, the curvature of the optical surface is likely to change.

  Therefore, a technique has been proposed in which the optical surface of the scanning optical element is similarly deformed by pressing the scanning optical element against the holding member via a spherical object (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-315536

  However, even if the scanning optical element is similarly deformed, the change in the curvature of the optical surface is not sufficiently suppressed, and it is difficult to eliminate the influence of the temperature change.

  The present invention has been made in order to solve the problems associated with the above-described conventional technology, and eliminates the influence of temperature changes, and provides a scanning optical device that can stably realize high image quality of image formation on a photoreceptor. The purpose is to provide.

  The above object of the present invention is achieved by the following means.

(1) a long scanning optical element having an optical surface for forming an image of light output from a light source on a photosensitive member;
Guiding means for inducing deformation due to expansion or contraction of the scanning optical element based on a temperature change in a direction to maintain the curvature of the optical surface ;
The guide means includes
A convex portion provided on the scanning optical element;
A holding member having a seating surface in contact with the convex part;
A pressing means for pressing the convex portion against the seat surface;
A scanning optical device comprising:

( 2 ) The convex portion is located at both ends of a rib portion arranged so as to surround the optical surface in the longitudinal direction of the scanning optical element corresponding to the main scanning direction. 1 ) The scanning optical device according to item 1 ).

( 3 ) The scanning optical element is curved along the longitudinal direction,
The scanning optical apparatus according to ( 2 ), wherein the seating surface has an angle with respect to the longitudinal direction.

( 4 ) The scanning optical device according to ( 3 ), wherein the seating surface has an angle of 85 to 90 degrees with respect to a normal line with respect to a longitudinal end portion of the optical surface.

( 5 ) The scanning optical device according to ( 3 ), wherein the seating surface is perpendicular to a normal line with respect to a longitudinal end portion of the optical surface.

( 6 ) The seating surface is at an angle of 85 to 90 degrees with respect to a connecting line connecting the contact position of the seating surface and the convex portion and the contact position of the pressing member and the scanning optical element. The scanning optical apparatus according to ( 3 ) above, characterized by comprising:

( 7 ) The seating surface has an angle of 90 degrees with respect to a connecting line connecting the contact position of the seating surface and the convex portion and the contact position of the pressing member and the scanning optical element. The scanning optical device according to ( 3 ) above, wherein

( 8 ) The optical surface of the scanning optical element comprises a mirror,
( 3 ), wherein the convex portion is formed on a surface perpendicular to the thickness direction of the scanning optical element, and is located outside the optical surface with respect to the longitudinal direction. The scanning optical device described.

( 9 ) The optical surface of the scanning optical element comprises a lens,
In the above ( 3 ), the convex portion is formed on a surface perpendicular to the optical axis direction of the optical surface, and is located outside the optical surface with respect to the longitudinal direction. The scanning optical device described.

( 10 ) The scanning optical element has a second convex portion arranged on the back surface of the convex portion,
The scanning optical apparatus according to (8) or (9) , wherein the pressing unit includes an elastic member that is in contact with the second convex portion and applies a pressing force to the scanning optical element. .

( 11 ) The pressing means includes a convex portion that contacts the scanning optical element, and an elastic member that applies a pressing force to the scanning optical element via the convex portion,
The both end portions include an end surface on which the convex portion in contact with the seat surface of the holding member is disposed, and a seat surface in contact with the convex portion of the pressing means and to which the pressing force is applied. The scanning optical apparatus according to ( 3 ) above.

( 12 ) The scanning optical device according to ( 11 ), wherein the seating surfaces at both ends are parallel to the seating surface of the holding member.

( 13 ) The guide means includes
A second holding member having a seating surface in contact with an intermediate portion located between the both end portions;
The scanning optical apparatus according to ( 3 ), further comprising a second pressing unit that presses the intermediate portion against a seating surface of the second holding member.

( 14 ) The seating surface of the second holding member is
It is perpendicular to a connecting line connecting the contact position between the second pressing means and the scanning optical element and the contact position between the seating surface of the second holding member and the scanning optical element. ,And,
The scanning optical apparatus according to ( 13 ), wherein the connecting line is parallel to the direction of the pressing force of the second pressing unit.

( 15 ) The optical surface of the scanning optical element comprises a mirror,
The scanning optical device according to ( 3 ) above, wherein the scanning optical device has a positioning portion for positioning the scanning optical element in the thickness direction.

( 16 ) The optical surface of the scanning optical element comprises a lens,
The scanning optical apparatus according to ( 3 ), wherein the scanning optical apparatus includes a positioning unit for positioning the optical surface in the optical axis direction.

( 17 ) The scanning optical apparatus according to ( 15 ) or ( 16 ) above, wherein the positioning portion is located at an intermediate portion located between the both end portions.

(18) the positioning unit, the scanning optical apparatus according to (17), characterized in that located in the central portion in the longitudinal direction of the scanning optical element.

( 19 ) The optical surface of the scanning optical element comprises a mirror,
The scanning optical element includes a rib portion disposed so as to surround the optical surface, a convex portion protruding from the rib portion and disposed with the optical surface, and located on the opposite side of the convex portion and the rib A recess recessed from the portion,
The said convex part and the said recessed part are aligned, The thickness between the said convex part and the said recessed part is in agreement with the thickness of the said rib part. The said ( 3 ) characterized by the above-mentioned. Scanning optical device.

( 20 ) The scanning optical device according to any one of (1) to ( 19 ), wherein the photoconductor is a photoconductor drum of an image forming apparatus.

  According to the present invention, the deformation due to the expansion or contraction of the scanning optical element based on the temperature change is induced in the direction of maintaining the curvature of the optical surface, so that the change in the curvature of the optical surface at the time of the temperature change is suppressed, which is favorable. Optical properties are maintained. Therefore, it is possible to provide a scanning optical device that can eliminate the influence of temperature change and stably realize high image quality of image formation on the photoreceptor.

1 is a cross-sectional view for explaining an image forming apparatus according to an embodiment of the present invention. It is a top view for demonstrating the scanning optical apparatus shown by FIG. It is a top view for demonstrating the holder shown by FIG. It is a perspective view for demonstrating the holder shown by FIG. It is a front view for demonstrating the scanning optical element shown by FIG. FIG. 3 is a rear view for explaining the scanning optical element shown in FIG. 2. It is a bottom view for demonstrating the scanning optical element shown by FIG. It is an enlarged view for demonstrating the convex part of a scanning optical element, and the seat surface of a holding member. It is the schematic for demonstrating the deformation | transformation by the temperature change which concerns on embodiment of this invention. It is the schematic for demonstrating the deformation | transformation by the temperature change which concerns on a comparative example. It is a top view for demonstrating the modification 1 which concerns on embodiment of this invention. It is a perspective view for demonstrating the modification 2 which concerns on embodiment of this invention. It is an enlarged view for demonstrating the modification 3 which concerns on embodiment of this invention. It is a top view for demonstrating the modification 4 which concerns on embodiment of this invention. It is an enlarged view for demonstrating the modification 4 which concerns on embodiment of this invention. It is a top view for demonstrating the modification 5 which concerns on embodiment of this invention. It is a front view for demonstrating the scanning optical element shown by FIG. It is an enlarged view for demonstrating the scanning optical element shown by FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view for explaining an image forming apparatus according to an embodiment of the present invention.

  An image forming apparatus 100 shown in FIG. 1 is a tandem type color copier, and includes a control unit 110, an image reading unit 120, an operation display unit 130, an image forming unit 140, a transfer unit 150, a fixing unit 155, and a paper transport unit. 160.

  The control unit 110 is a control circuit configured by a microprocessor or the like that executes control of the above-described units and various arithmetic processes according to a program, and each function of the image forming apparatus 100 has a program corresponding to the control unit 110. It is demonstrated by executing.

  The image reading unit 120 is used to generate document image data, and includes a light source 122, an optical system 124, and an image sensor 126. The light source 122 irradiates light on the document placed on the reading surface 128, and the reflected light is imaged on the image sensor 126 that has moved to the reading position via the optical system 124. The image sensor 126 is composed of, for example, a line image sensor, and generates an electric signal (photoelectrically converts) in accordance with the reflected light intensity. The generated electrical signal is input to the image forming unit 140 after image processing. Image processing includes A / D conversion, shading correction, filter processing, image compression processing, and the like.

  The operation display unit 130 includes, for example, an LCD (Liquid Crystal Display) and a keyboard, and is used to present a device configuration, a print job progress status, an error occurrence status, a currently changeable setting, and the like to the user. Output means and input means used for the user to perform various instructions (inputs) such as character input, various settings, and start instructions. The keyboard has a plurality of keys including a selection key for specifying the size of the paper P, a numeric keypad for setting the number of copies, a start key for instructing start of operation, a stop key for instructing stop of operation, and the like.

  The image forming unit 140 uses an electrophotographic process that uses toner, and is used to form an image on a paper P that is a recording medium. The image forming unit 140 forms an image of yellow (Y) color, magenta ( M) an image forming unit 140B that forms an image of color, an image forming unit 140C that forms an image of cyan (C), and an image forming unit 140D that forms an image of black (K).

  Each unit of the image forming unit 140 includes a photosensitive drum 142, a charging unit 143, an optical writing unit 145, a developing device 146, and a cleaning unit 148.

  The photosensitive drum 142 includes a photosensitive layer made of a resin such as polycarbonate including an organic photoconductor (OPC), and is configured to rotate at a predetermined speed. The charging unit 143 includes a corona discharge electrode arranged around the photosensitive drum 142, and charges the surface of the photosensitive drum 142 with the generated ions.

  The optical writing unit 145 incorporates a scanning optical device 170 and exposes the charged photosensitive drum 142 based on the image data input from the image reading unit 120, thereby exposing the exposed portion. The electric potential is lowered to form a charge pattern (electrostatic latent image) corresponding to the image data. As will be described later, the scanning optical device 170 is configured to eliminate the influence of temperature changes and stably realize high image quality on the photosensitive member.

  The developing device 146 develops the formed electrostatic latent image and visualizes it with toner. That is, it is possible to form monochrome images of toners corresponding to yellow, magenta, cyan and black on the photosensitive drums 142 of the image forming units 140A, 140B, 140C and 140D, respectively.

  After the monochrome image is transferred to the intermediate transfer belt 151, the cleaning unit 148 scrapes (removes) the residual toner and external additives remaining on the surface of the photosensitive drum 142 to thereby change the surface state. Used to keep good.

  The transfer unit 150 includes an intermediate transfer belt 151, a primary transfer unit 153, and a secondary transfer unit 154. The intermediate transfer belt 151 is wound around a primary transfer unit 153 and a plurality of rollers, and is supported so as to be able to run. The primary transfer unit 153 includes primary transfer modules 153A, 153B, 153C, and 153D corresponding to yellow, magenta, cyan, and black. The secondary transfer unit 154 is disposed outside the intermediate transfer belt 151 and is configured to allow the paper P to pass between the intermediate transfer belt 151.

  The monochrome images of the respective colors formed in the image forming units 140A to 140D are sequentially transferred onto the intermediate transfer belt 151 by the primary transfer modules 153A to 153D, and the yellow, magenta, cyan, and black layers are superimposed. A color image is formed. The formed color image is transferred to the conveyed paper P by the secondary transfer unit 154.

  The fixing unit 155 is used for fixing the color image transferred to the paper P, and includes a heating roller 157 and a pressure roller 158. When the paper P passes between the heating roller 157 and the pressure roller 158, pressure and heat are applied to melt the toner, thereby fixing the color image.

  The paper transport unit 160 includes a paper feed unit 162, a registration roller 164, a fixing transport roller 165, a paper discharge roller 166, and a paper reversing unit 168.

  The paper feed unit 162 includes paper feed trays 162A to 162C that store paper P, a feed roller 163A, and a separation roller 163B. The feed roller 163A and the separation roller 163B feed sheets one by one from the sheet feed trays 162A to 162C to the transport path.

  The registration roller 164 conveys the paper P fed from the paper feeding unit 162 to the secondary transfer unit 154. The fixing conveyance roller 165 conveys the paper P that has passed through the secondary transfer unit 154 and the fixing unit 155 toward the paper discharge roller 166. The paper discharge roller 166 discharges the conveyed paper P to the outside of the apparatus.

  The paper reversing unit 168 introduces the paper P that has passed through the fixing conveyance roller 165 into a conveyance path between the paper feed trays 162 </ b> A to 162 </ b> C and the paper discharge roller 166 instead of a conveyance path toward the paper discharge roller 166. The sheet P is used to turn the paper P upside down and discharge it, or to form images on both sides of the paper P.

  Next, the scanning optical device 170 incorporated in the optical writing unit 145 will be described in detail.

  FIG. 2 is a plan view for explaining the scanning optical device shown in FIG.

  The scanning optical device 170 includes a light source 172, a light source holder 174, light source optical elements 176 and 178, a deflector 180, scanning optical elements 10 and 10A, optical element holders 50 and 50A, a condensing optical element (condensing lens) 182 and light. The sensor 184 is housed in a housing 186 formed of a box-shaped frame.

  The light source 172 is made of a semiconductor laser and is held by a light source holder 174 fixed to the housing 186 or integrally formed. The light source optical element 176 has a collimator lens and converts light emitted from the semiconductor laser into parallel light. The light source optical element 178 has a cylindrical lens and collects parallel light in the sub-scanning direction (converts it into convergent light). The deflector 180 includes a polygon mirror unit, and deflects the convergent light in the main scanning direction Y at an equal angular velocity. The main scanning direction Y and the sub scanning direction are orthogonal to each other.

  The scanning optical elements 10 and 10A have a long shape extending in the longitudinal direction (main scanning direction) Y, and are held by optical element holders 50 and 50A fixed to the housing 186 or integrally formed (attachment). The deflected light beam is condensed on the photosensitive drum 142, and the photosensitive drum 142 is scanned and exposed in the main scanning direction M. That is, the scanning optical elements 10 and 10 </ b> A are used to form an image of the light beam output from the light source 172 on the photosensitive drum 142.

  The condensing optical element 182 and the optical sensor 184 are used for adjusting the timing of the image writing position. The condensing optical element 182 condenses the light transmitted through the scanning optical element 10 toward the optical sensor 184, and the optical sensor 184 detects the light transmitted through the condensing optical element 182. The optical sensor 184 is composed of, for example, a photoelectric conversion element, and the detection signal is input to a control circuit (not shown) in order to generate a synchronization signal.

  Next, the optical element holder 50 and the scanning optical element 10 will be described in detail. The optical element holder 50A and the scanning optical element 10A have substantially the same configuration as that of the optical element holder 50 and the scanning optical element 10, and therefore the description thereof is omitted to avoid duplication.

  3 and 4 are a plan view and a perspective view for explaining the holder shown in FIG. 2, and FIGS. 5, 6 and 7 are front views for explaining the scanning optical element shown in FIG. It is a rear view and a bottom view.

  The optical element holder 50 is used for positioning and holding the scanning optical element 10, and has a base 52, a holding member 60, and a pressing means 70. The base 52 has a recess 54 for positioning the scanning optical element 10, and is attached to the housing 186 of the scanning optical device 170.

The holding member 60 has a seating surface 62 that comes into contact with the scanning optical element 10. The pressing means 70 includes a support portion 74 that is fixed to the base portion 52, and a leaf spring 72 that is attached to the support portion 74. The leaf spring 72 is an elastic member that applies a pressing force F ₁ to the scanning optical element 10.

  The scanning optical element 10 has optical surfaces 22 and 24, a rib portion 12, convex portions 30 and 32, and a protruding portion 40. The optical surfaces 22 and 24 are curved along the longitudinal direction (main scanning direction) Y, and are composed of lenses that transmit light. The rib portion 12 is disposed so as to surround the optical surfaces 22 and 24.

  The convex portions 30 and 32 are hemispherical and are arranged at both end portions 14 in the longitudinal direction Y of the rib portion 12, the convex portion 30 is located on the optical surface 20 side, and the convex portion 32 is on the optical surface 22 side. To position. That is, the convex portions 30 and 32 are formed on a surface perpendicular to the optical axis direction of the optical surfaces 22 and 24 and are located outside the optical surfaces 22 and 24 with respect to the longitudinal direction Y. The shape of the convex portions 30 and 32 is not limited to a hemispherical shape. The number of the protrusions 30 and 32 can be set to one each, or can be different (asymmetric number).

  The protrusion 40 is disposed on the bottom surface of the scanning optical element 10, is located in the center portion in the longitudinal direction Y of the rib portion 12, and is engaged with the recess 54 disposed in the base 52 of the optical element holder 50. The optical surfaces 22 and 24 function as positioning portions for positioning in the optical axis direction.

  The protrusion 40 is not limited to the form located in the center part of the rib part 12 in the longitudinal direction Y, and the installation position is set between the both end parts 14 (intermediate part) of the rib part 12 in the longitudinal direction Y as necessary. It is also possible to change appropriately. Plural protrusions 40 can be arranged apart from each other, or can be disposed on the top surface in addition to the bottom surface of the scanning optical element 10. When the protrusions 40 are disposed on the top surface, the optical element holder 50 is In this case, the upper structure body having the concave portion and the base portion 52 is provided. It is also possible to arrange a concave portion in the scanning optical element 10 and arrange a convex portion in the optical element holder 50.

  Note that Z represents a direction (short direction) orthogonal to the longitudinal direction (main scanning direction) Y and corresponds to the sub-scanning direction. A symbol X represents a direction orthogonal to the YZ plane.

  FIG. 8 is an enlarged view for explaining the convex portion of the scanning optical element and the seating surface of the holding member, and FIGS. 9 and 10 are for explaining deformation due to temperature change according to the embodiment of the present invention and the comparative example. FIG. In FIGS. 9 and 10, the solid line is before the temperature change, and the broken line is after the temperature rise.

The convex portion 30 and the convex portion 32 of the scanning optical element 10 are aligned (in a symmetrical position with respect to both end portions 14), the convex portion 30 is in contact with the seat surface 62 of the holding member 60, and the convex portion 32 is It is in contact with the leaf spring 72 of the pressing means 70. The leaf spring 72 is biased so as to apply a pressing force F ₁ toward the scanning optical element 10 and presses the convex portion 30 against the seat surface 62 of the holding member 60 via the convex portion 32.

The seat surface 62 has an angle with respect to the longitudinal direction Y, and is inclined with respect to the normals NL ₁ and NL _{2 with} respect to the end portions 21 and 23 in the longitudinal direction Y of the optical surfaces 22 and 24 of the scanning optical element 10. doing. The angle of the seating surface 62 with respect to the normals NL ₁ and NL ₂ is set to be vertical, but is not particularly limited thereto. However, a range of 85-90 degrees is preferred.

The convex portion 32 and the leaf spring 72 are in contact position, connecting line CL ₁ that connects the seating surface 62 and a position in contact has a convex portion 30 and the holding member 60 is perpendicular to the seating surface 26 (normal NL ₁ , parallel to NL ₂ ) and parallel to the direction of the pressing force F ₁ applied by the leaf spring 72. Angle to the connection line CL ₁ of the seating surface 62 is not limited vertically, preferably in the range of 85 to 90 degrees.

Therefore, when the scanning optical element 10 is thermally expanded with a temperature change, the upward deformation is suppressed by the pressing force F ₁ applied by the leaf spring 72 in contact with the convex portion 32, and the seating surface in contact with the convex portion 30. Therefore, as shown in FIG. 9, the curvature change of the optical surfaces 20 and 22 is small, and the curvature of the optical surfaces 20 and 22 is maintained.

On the other hand, in the scanning optical element 210 according to the comparative example, as shown in FIG. 10, the seating surface 262 of the holding member 260 is parallel to the longitudinal direction Y, and the convex portion 232 and the leaf spring 272 are in contact with each other. position and, connecting line CL ₁ that connects and the contacts positioned protrusion 230 and the seating surface 262, a is set at an angle with respect to the normal line _NL 1, NL _2. In this case, when the scanning optical element 210 is thermally expanded as the temperature changes, the scanning optical element 210 is guided along the seating surface 262 that has no angle in the longitudinal direction Y and is not perpendicular to the normals NL ₁ and NL _2. Unlike the optical element 10, the curvatures of the optical surfaces 220 and 222 change greatly.

  That is, in the present embodiment, the convex portions 30 and 32, the holding member 60, and the pressing unit 70 of the scanning optical element 10 are deformed by the expansion or contraction of the scanning optical element 10 based on the temperature change. The guide means for guiding in the direction of maintaining the curvature is configured, and the deformation due to the expansion or contraction of the scanning optical element 10 based on the temperature change is guided in the direction of maintaining the curvature of the optical surfaces 20 and 22. The curvature change of the optical surfaces 20 and 22 at the time of a change is suppressed, and a favorable optical characteristic is maintained.

Further, the convex portion 30 and the convex portion 32 of the scanning optical element 10, (due to the symmetrical positions with respect to both end portions 14) because they are aligned, the direction of the pressing force F ₁ applied by the leaf spring 72, it is easy to parallel to the connecting line CL _1.

  Next, modifications 1 to 5 according to the embodiment of the present invention will be described in order.

  FIG. 11 is a plan view for explaining Modification 1 according to the embodiment of the present invention.

  The optical surface of the scanning optical element is not limited to a form constituted by a lens that transmits light, and can be constituted by an optical surface that reflects light or an optical surface that diffracts light. For example, the scanning optical element 10A according to Modification 1 shown in FIG. 11 has an optical surface 20A, convex portions 30 and 32, and a protruding portion 40A. The optical surface 20A is composed of a mirror that reflects light. The convex portions 30 and 32 are formed on a surface perpendicular to the thickness direction of the scanning optical element 10A, and are located outside the optical surface 20A with respect to the longitudinal direction Y. The protrusion 40A functions as a positioning part for positioning in the thickness direction of the scanning optical element 10A. Since optical surface 20A is composed of a mirror, no optical surface is disposed on the opposite side of the surface on which optical surface 20A is disposed.

  Even in this case, the deformation due to the expansion or contraction of the scanning optical element 10A based on the temperature change is induced in the direction of maintaining the curvature of the optical surface 20A. Therefore, the change in the curvature of the optical surface 20A at the time of the temperature change is suppressed. Good optical properties are maintained.

  FIG. 12 is a perspective view for explaining a modification 2 according to the embodiment of the present invention.

  The scanning optical element 10 </ b> B according to the modification 2 is generally different from the modification 1 in that the scanning optical element 10 </ b> B has a convex portion 16 and a concave portion 18.

  The convex part 16 protrudes from the rib part 12, and an optical surface 20A composed of a mirror is disposed. The concave portion 18 is recessed from the rib portion 12 and is aligned with the convex portion 16 (located on the opposite side of the surface on which the optical surface 20A is disposed and corresponds to the back surface of the optical surface 20A). The thickness between the convex portion 16 and the concave portion 18 matches the thickness of the rib portion 12.

  In this case, the optical surface 20A is easily formed because it is disposed on the convex portion 16. On the other hand, since the thickness of the scanning optical element 10B is constant, the occurrence of stress due to the presence of the convex portion 16 is suppressed.

  FIG. 13 is an enlarged view for explaining a third modification according to the embodiment of the present invention.

  The convex portion 30 and the convex portion 32 of the scanning optical element 10C are not limited to the form in which they are aligned (symmetrical with respect to the both end portions 14). For example, as in the scanning optical element 10C according to the third modification example It is also possible to offset (asymmetric). In this case, the portion on the opposite side of the arrangement portion of the convex portions 30 and 32 is flat and there is a space, so that the degree of freedom of arrangement of the scanning optical element 10C is improved and the moldability of the scanning optical element 10C is improved. Improve (easily molded).

  14 and 15 are a plan view and an enlarged view for explaining a fourth modification according to the embodiment of the present invention.

  The modification 4 is generally different from the modification 1 with respect to the shape of the both end portions 14 of the scanning optical element 10 </ b> D and the configuration of the pressing means 70.

Both end portions 14 have a convex portion 30 disposed on the end surface 14A and a seat surface 14B that is parallel to and flat with respect to the seat surface 62 of the holding member 60, and the convex portion 32 is not disposed. The pressing means 70 has a hemispherical convex portion 76 disposed on the leaf spring 72. The convex portion 76 is in contact with the seating surface 14 </ b> B and is configured to apply a pressing force F ₁ to both end portions 14.

  In this case, since the convex portion 32 is not provided and the convex portion 30 is not disposed on a surface perpendicular to the thickness direction of the scanning optical element, the application is easy even when the curvature of the optical surface 20A is large. Thus, the degree of freedom of the arrangement of the scanning optical element 10C is improved, and the moldability of the scanning optical element 10C is improved (molding is easy).

  FIG. 16 is a plan view for explaining a modification 5 according to the embodiment of the present invention, and FIGS. 17 and 18 are a front view and an enlarged view for explaining the scanning optical element shown in FIG.

  As shown in FIG. 16, the modified example 5 is generally different from the modified example 1 in that it includes the second convex portions 30 </ b> E and 32 </ b> E, the second holding member 60 </ b> E, and the second pressing means 70 </ b> E.

The convex portions 30E and 32E are hemispherical, and as shown in FIG. 17, the convex portions 30E and 32E are disposed at the intermediate portion 13 located between both end portions 14 of the rib portion 12 of the scanning optical element 10E. Located on the surface 20A side, the convex portion 32E is located on the opposite side of the optical surface 20A. The holding member 60E has a seat surface 62E that contacts the convex portion 30E. Pressing means 70E adds the pressing force _{F 2} to the convex portions 32E, are used to press the protrusion 30E to the seating surface 62E.

As shown in FIG. 18, the seating surface 62E of the holding member 60E is a connecting line that connects the abutting position between the pressing means 70E and the convex portion 32E and the abutting position between the seating surface 62E and the convex portion 30E. It is perpendicular to CL _2, and the direction of the pressing force F ₂ is set to be parallel to the connecting line CL _2.

Therefore, when the scanning optical element 10E is thermally expanded as the temperature changes, even with respect to intermediate portion 13, deformation upward is prevented by the pressing force F ₂ applied by the pressing means 70E in contact with the convex portions 32E, the convex portions 30E Therefore, the curvature change of the optical surface 20A related to the intermediate portion 13 is small, and the curvature of the optical surface 20A is maintained. That is, the effect of guiding in the direction of maintaining the curvature of the optical surface 20A is improved. In addition, the number of installation of the convex parts 30E and 32E, the holding member 60E, and the pressing means 70E is not limited to four, It is possible to set suitably as needed.

  As described above, in the present embodiment, the deformation due to expansion or contraction of the scanning optical element based on the temperature change is induced in the direction of maintaining the curvature of the optical surface. Is suppressed, and good optical characteristics are maintained. Therefore, it is possible to provide a scanning optical device that can eliminate the influence of temperature change and stably realize high image quality of image formation on the photoreceptor.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, the modification 3 is applied to a scanning optical element having an optical surface composed of a mirror that reflects light, or the modification 4 and the modification 5 have an optical surface composed of a lens that transmits light. It can be applied to a scanning optical element. Further, the image forming apparatus to which the scanning optical device is applied is not limited to a copying machine, and it is also possible to apply a printer dedicated to printing, or an MFP (Multi-Function Peripheral) having a copy function, a printer function, and a scan function. It is.

10, 10A-10E scanning optical element,
12 ribs,
13 middle part,
14 both ends,
14A end face,
14B bearing surface,
16 convex part,
18 recess,
20, 20A, 22 optical surface,
21 end,
26 seating surface,
30, 30E convex part,
32, 32E convex part,
40, 40A protrusion,
50, 50A optical element holder,
52 base,
54 recess,
60, 60E holding member,
62, 62E bearing surface,
70, 70E pressing means,
72 leaf spring,
74 support,
76 convex part,
100 image forming apparatus,
110 control unit,
120 image reading unit,
122 light source,
124 optical system,
126 imaging device,
128 reading surface,
130 operation display section,
140 Image forming unit,
140A-140D image forming unit,
142 photosensitive drum,
143 charging unit,
145 optical writing unit,
146 Development device,
148 Cleaning section,
150 Transfer section,
151 Intermediate transfer belt,
153 Primary transfer part,
153A to 153D primary transfer module,
154 secondary transfer part,
155 fixing unit,
157 heating roller,
158 pressure roller,
160 paper transport section,
162 paper feeder,
162A paper feed tray,
163A delivery roller,
163B judgment roller,
164 Registration roller,
165 fixing conveyance roller,
166 paper discharge roller,
168 Paper reversing section,
170 scanning optical device,
172 light source,
174 light source holder,
176,178 light source optical element,
180 deflector,
182 Condensing optical element (condensing lens),
184 light sensor,
186 housing,
CL ₁ and CL ₂ connecting lines,
F ₁ , F ₂ pressing force,
P paper,
NL ₁ , NL ₂ normal,
A direction perpendicular to the XYZ plane,
Y longitudinal direction (main scanning direction),
Z Short direction (sub-scanning direction).

Claims (20)

An elongated scanning optical element having an optical surface for imaging light output from the light source on the photosensitive member;
Guiding means for inducing deformation due to expansion or contraction of the scanning optical element based on a temperature change in a direction to maintain the curvature of the optical surface ;
The guide means includes
A convex portion provided on the scanning optical element;
A holding member having a seating surface in contact with the convex part;
A pressing means for pressing the convex portion against the seat surface;
A scanning optical device comprising: The convex portion is directed to the longitudinal direction of the scanning optical element corresponding to the main scanning direction, according to claim 1, characterized in that located at both ends of the rib portion arranged to surround the optical surface Scanning optical device. The scanning optical element is curved along the longitudinal direction;
The scanning optical device according to claim 2 , wherein the seating surface has an angle with respect to the longitudinal direction. The scanning optical apparatus according to claim 3 , wherein the seating surface has an angle of 85 to 90 degrees with respect to a normal line with respect to a longitudinal end portion of the optical surface. The scanning optical device according to claim 3 , wherein the seating surface is perpendicular to a normal line with respect to a longitudinal end portion of the optical surface. The seat surface has an angle of 85 to 90 degrees with respect to a connecting line connecting the contact position of the seat surface and the convex portion and the contact position of the pressing member and the scanning optical element. The scanning optical apparatus according to claim 3 . The seating surface has an angle of 90 degrees with respect to a connecting line connecting the contact position between the seating surface and the convex portion and the contact position between the pressing member and the scanning optical element. The scanning optical device according to claim 3 . The optical surface of the scanning optical element comprises a mirror,
The convex portions, according to claim 3, wherein the scanning is formed in a plane perpendicular to the thickness direction of the optical element, and is characterized in that located on the outside of the optical surface relative to the longitudinal direction Scanning optical device. The optical surface of the scanning optical element comprises a lens,
The convex portions, according to claim 3, wherein is formed in a plane perpendicular to the optical axis of the optical surface, and is characterized in that located on the outside of the optical surface relative to the longitudinal direction Scanning optical device. The scanning optical element has a second convex portion disposed on the back surface of the convex portion,
It said pressing means, the scanning optical apparatus according to claim 8 or claim 9, characterized in that have a resilient member for adding a pressing force to the second protrusion and the contact and the scanning optical element. The pressing means includes a convex portion that contacts the scanning optical element, and an elastic member that applies a pressing force to the scanning optical element via the convex portion,
The both end portions include an end surface on which the convex portion in contact with the seat surface of the holding member is disposed, and a seat surface in contact with the convex portion of the pressing means and to which the pressing force is applied. The scanning optical device according to claim 3 . The scanning optical device according to claim 11 , wherein the seating surfaces at both ends are parallel to the seating surface of the holding member. The guide means includes
A second holding member having a seating surface in contact with an intermediate portion located between the both ends,
The scanning optical apparatus according to claim 3 , further comprising a second pressing unit that presses the intermediate portion against a seating surface of the second holding member. The seating surface of the second holding member is
It is perpendicular to a connecting line connecting the contact position between the second pressing means and the scanning optical element and the contact position between the seating surface of the second holding member and the scanning optical element. ,And,
The scanning optical device according to claim 13 , wherein the connecting line is parallel to a direction of a pressing force of the second pressing unit. The optical surface of the scanning optical element comprises a mirror,
The scanning optical apparatus according to claim 3 , wherein the scanning optical apparatus includes a positioning unit for positioning the scanning optical element in a thickness direction. The optical surface of the scanning optical element comprises a lens,
The scanning optical device according to claim 3 , wherein the scanning optical device has a positioning portion for positioning the optical surface in the optical axis direction. The scanning optical device according to claim 15 or 16 , wherein the positioning portion is located in an intermediate portion located between the both end portions. The scanning optical device according to claim 17 , wherein the positioning portion is located at a central portion in a longitudinal direction of the scanning optical element. The optical surface of the scanning optical element comprises a mirror,
The scanning optical element includes a rib portion disposed so as to surround the optical surface, a convex portion protruding from the rib portion and disposed with the optical surface, and located on the opposite side of the convex portion and the rib A recess recessed from the portion,
The scanning according to claim 3 , wherein the convex portion and the concave portion are aligned with each other, and a thickness between the convex portion and the concave portion coincides with a thickness of the rib portion. Optical device. The photoreceptor scanning optical apparatus according to any one of claims 1 to 19, characterized in that a photosensitive drum of the image forming apparatus.

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