JP2011197081A - Optical scanning apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanning apparatus that highly accurately positions and holds an optical element on a holder, and that suppresses deterioration in optical characteristics as much as possible in the time of thermal deformation.SOLUTION: This is an optical scanning apparatus that deflects and scans light radiated from a light source in a main scanning direction Y by a scanning lens 13 or the like. The scanning lens 13 is elongated in the main scanning direction Y and has a flat mounting reference face 13a on one side. A lens holder 30 has: a positioning bearing surface 33 that supports the mounting reference face 13a of the scanning lens 13 at least at three points on the X-Y plane and an adhesive bearing surface 36 that is for forming a filling space 40 between it and the mounting reference face 13a for the purpose of filling an adhesive 50. The scanning lens 13 is positioned and adjusted on the positioning bearing surface 33 in accordance with advance or retreat of a screw member 45, in the state where the mounting reference face 13a is elastically held with pressure on the positioning bearing surface 33 with a leaf spring 43. After this positional adjustment, the adhesive 50 is charged in the filling space 40 and hardened.

Description

  The present invention relates to an optical scanning optical device, and more particularly to an optical scanning optical device mounted as an image writing unit in an image forming apparatus such as an electrophotographic copying machine or printer.

  In general, in this type of optical scanning optical apparatus, an optical element such as a scanning lens has a long shape extending in the main scanning direction, is placed on the positioning seating surface of the element holder, and is pressed by an elastic member It is fixed with adhesive. In the finishing stage of the assembly process, in order to satisfy predetermined optical performance, the position of the optical element is adjusted on the element holder by the adjusting member while confirming the actually emitted light beam.

  In recent years, the resolution of image forming apparatuses has been increased, and there has been an increasing demand for optical elements to be accurately arranged at design positions on a holder and to maintain the optical performance as much as possible even when temperature changes occur. Therefore, various problems when the optical element is bonded and fixed on the holder have been studied.

  Patent Document 1 describes that an optical element is placed on a holder in a state where an adhesive is applied in advance, and the position of the optical element is adjusted while checking optical performance. Two points on both ends of the long optical element in the main scanning direction are used as adhesive fixing points. However, in this adjustment technique, the optical element is adjusted and moved while the adhesive is applied to the pedestal of the holder, so that the adhesive sandwiched between the pedestal and the optical element is stretched to form an irregular shape. It may be deformed. After the adjustment, when the internal temperature of the optical scanning optical device changes (rises) and thermal expansion occurs in the optical element or the holder, ideally, the optical element is desirably deformed from the center. However, when the adhesive is hardened in an irregular shape, the optical element expands and contracts without an ideal similar deformation, and the optical performance may be deteriorated.

  On the other hand, Patent Document 2 describes that a guide is provided on the adhesive application surface of the housing in order to regulate expansion and contraction caused by thermal expansion in the longitudinal direction of the long lens. However, since the adhesive is applied before adjusting the position of the optical element, the movement of the optical element during adjustment causes “rubbing” to the adhesive, and the problem that the adhesive hardens in an irregular shape. It is left.

JP 2008-3373 A JP 2007-127793 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanning optical device that can position and hold an optical element on a holder with high accuracy and can suppress deterioration of optical performance during thermal deformation as much as possible.

An optical scanning optical device according to an aspect of the present invention is
In an optical scanning optical device that deflects and scans light emitted from a light source in a main scanning direction by a predetermined optical element,
An elongated optical element extending in the main scanning direction and having a flat mounting reference surface on one surface;
An element having an adhesive seating surface for forming a filling space between a positioning seating surface for holding the mounting reference surface of the optical element on at least three points on a plane and the mounting reference surface for filling with an adhesive. A holder,
An elastic member that elastically presses the mounting reference surface of the optical element onto the positioning seating surface of the element holder;
An adjustment member for adjusting the position of the optical element on the positioning seating surface of the element holder;
With
The filling space has a substantially symmetrical shape with respect to the central axis in the main scanning direction,
After adjusting the position of the optical element with the adjusting member, the filling space was filled with an adhesive and cured,
It is characterized by.

  In the optical scanning optical device, the long optical element extending in the main scanning direction is positioned and held on the element holder with high accuracy after the position adjustment. Since the optical element is fixed by an adhesive filled in a filling space having a substantially symmetric shape with respect to the central axis in the scanning direction, the optical element is deformed in a substantially symmetrical manner and optical performance is deteriorated. It can be suppressed. In addition, after the optical element is positioned, the filling space is filled with an adhesive and cured, so that the adhesive does not distort as a result of “rubbing” due to the position adjustment compared to the case where the position is adjusted after curing. Also in this respect, deterioration of the optical performance at the time of thermal deformation of the optical element and the holder can be suppressed.

  According to the present invention, the optical element can be positioned and held on the holder with high accuracy, and deterioration of optical performance during thermal deformation can be suppressed as much as possible.

1 is a schematic perspective view showing an optical scanning optical device according to an embodiment of the present invention. It is a schematic plan view which shows the principal part of the said optical scanning optical apparatus. It is a front view which shows the position adjustment mechanism and adhesion fixing mechanism of an optical element. The 1st example of an adhesion seat surface is shown, (A) is a perspective view and (B) is a sectional view. The 2nd example of an adhesion seat surface is shown, (A) is a perspective view and (B) is a sectional view. The 3rd example of an adhesion seat surface is shown, (A) is a perspective view and (B) is a sectional view. The 4th example of an adhesion seating surface is shown, (A) is a perspective view and (B) and (C) are sectional views. (A), (B), (C) is explanatory drawing which shows the adhesion state of an optical element. (A), (B), (C) is explanatory drawing which shows the mode of the ideal thermal expansion of an optical element.

  Embodiments of an optical scanning optical device according to the present invention will be described below with reference to the accompanying drawings. In each figure, common parts and portions are denoted by the same reference numerals, and redundant description is omitted.

(Schematic configuration of optical scanning optical device, see FIG. 1)
As shown in FIG. 1, an optical scanning optical apparatus according to an embodiment of the present invention is roughly shown as a laser diode 1, a collimator lens 2, mirrors 3 and 4, a cylinder lens 5, a polygon mirror 10, and lenses 11, 12, and 13. , 14, mirrors 15, 16, lens 17, and dust-proof glass 18, and the basic configuration is well known. The light beam emitted from the laser diode 1 is deflected at a constant angular velocity in the main scanning direction Y by the polygon mirror 10, and the aberration in the main scanning direction Y is corrected by the scanning lenses 11, 12, and 13 having the fθ function. Scan / exposure with the image formed above. Incidentally, in each figure, the arrow X indicates the traveling direction of the light beam, and the arrow Z indicates the sub-scanning direction.

  The scanning lenses 11, 12, and 13 have a long shape extending in the main scanning direction Y, and are integrally assembled as a unit on the lens holder 30 as shown in FIG. The scanning lenses 11, 12, and 13 have an attachment reference surface whose bottom surface is flat on the XY plane. The lens holder 30 is filled with positioning seating surfaces 31, 32, 33 for holding the reference mounting surfaces of the scanning lenses 11, 12, 13 at three points on the XY plane, and an adhesive 50 (see FIG. 3). For this purpose, adhesive seating surfaces 34, 35, and 36 for forming a filling space 40 between the mounting reference surface and the mounting reference surface are provided on the XY plane. Each scanning lens 11, 12, 13 is elastically pressed from above by the leaf springs 41, 42, 43 while being placed on the mounting reference surfaces 31, 32, 33, and is described below. After the adjustment, the filling space 40 is filled with the adhesive 50 and fixed in a cured state.

  Here, the position adjustment mechanism and the adhesion mechanism of the scanning lens 13 will be described with reference to FIG. The other scanning lenses 11 and 12 have the same mechanism. Further, the description of the thermal deformation and the like regarding the scanning lens 13 is also valid for the other scanning lenses 11 and 12.

  As shown in FIG. 3, one end of the scanning lens 13 is elastically urged toward the center of the optical axis in the arrow Y direction by a spring member (not shown), and the other end is pressed by a screw member 45. Therefore, the scanning lens 13 is adjusted in the main scanning direction Y on the positioning seating surface 33 by moving the screw member 45 back and forth. This position adjustment is performed while observing the light beam at an equivalent position to the photoconductor 20 while actually emitting the laser diode 1 in a state where the adhesive 50 is not filled. Therefore, the position adjustment can be performed with high accuracy.

  After the position adjustment, the adhesive 50 is filled in the filling space 40 (the gap between the adhesive seating surface 36 and the reference surface 13a) and cured. As the adhesive 50, it is preferable to use an ultraviolet curing type or a visible light curing type. Since the scanning lens 13 is made of a transparent material, the adhesive 50 can be easily cured by irradiating light from above the scanning lens 13 (see arrow a).

  The scanning lens 13 is made of glass or transparent resin, and the lens holder 30 is made of aluminum die-cast or high-rigidity resin. When thermal expansion occurs in these members, positional deviation occurs between the scanning lens 13 and the lens holder 30 due to the difference in linear expansion coefficient. When the scanning lens 13 is a glass material and the lens holder 30 is an aluminum material, the aluminum material has a larger linear expansion coefficient. Therefore, at the time of thermal expansion, in addition to the thermal expansion of the scanning lens 13 itself, the adhesive 50 serves as an anchor, and the scanning lens 13 is deformed as the lens holder 30 expands.

  In the case of the long scanning lens 13, the adhesive fixing position is symmetrically arranged in the longitudinal direction, and the filling space 40 has a symmetrical shape, so that the scanning lens 13 has a similar deformation with little influence on the optical performance. It becomes possible to make it. At the same time, it is desirable that the adhesive 50 is substantially circular or substantially oval in a cured state, or is substantially linear in the direction in which the scanning lens 13 or the lens holder 30 thermally expands. When it becomes distorted, the scanning lens 13 is prevented from ideally deforming symmetrically in the left-right direction during thermal deformation, and the optical performance cannot be maintained.

  From the above viewpoint, the adhesive seating surface 36 preferably has various configurations and shapes as shown in FIGS.

  In the first example shown in FIG. 4, a pair of restricting portions 36 a is provided on the circular adhesive seating surface 36 to form a linear filling space 40, and the adhesive 50 is one end (filling port) of the filling space 40. A syringe is inserted from 40a and injected. FIG. 8A shows a state in which the scanning lens 13 is bonded and fixed using the adhesive seating surface 36, and the state of the scanning lens 13 during thermal expansion is shown by a dotted line in FIG. 9A. Since the adhesive 50 is linearly cured in the thermal expansion direction of the scanning lens 13 by the restricting portion 36a, the scanning lens 13 is ideally deformed symmetrically to the left and right, and deterioration of optical performance is suppressed as much as possible.

  The second example shown in FIG. 5 is a filling space 40 in which a pair of restricting portions 36a are provided on a circular adhesive seating surface 36 and a through hole 36b is formed. It is injected from the rear surface side of the lens holder 30. The operational effects of the second example are the same as those of the first example.

  In the third example shown in FIG. 6, a pair of bent regulating portions 36 a is provided on the circular adhesive seating surface 36 to form a linear filling space 40, and the adhesive 50 is provided at one end (filling port) of the filling space 40. ) A syringe is inserted from 40a and injected. A state in which the scanning lens 13 is bonded and fixed using the adhesive seating surface 36 is shown in FIG. 8B, and the state of the scanning lens 13 during thermal expansion is shown by a dotted line in FIG. By bending the restricting portion 36a in accordance with the direction of thermal expansion of the scanning lens 13, it is possible to suppress deterioration of optical performance in a more preferable state.

  The fourth example shown in FIG. 7 is a filling space 40 provided with a regulating portion 36a whose central portion swells on a circular adhesive seating surface 36. One end (filling port) 40a of the filling space 40 is narrowed and a syringe is used. The tip of can be inserted without gaps. A state in which the scanning lens 13 is bonded and fixed using the adhesive seating surface 36 is shown in FIG. 8C, and the state of the scanning lens 13 during thermal expansion is shown by a dotted line in FIG. 9C. The effect is the same as that of the first example.

(Other examples)
The optical scanning optical device according to the present invention is not limited to the above-described embodiments, and can be variously modified within the scope of the gist thereof.

  In particular, the configuration and arrangement of the light source optical system and the scanning optical system are arbitrary. The detailed structure and shape of the lens holder are also arbitrary, and the lens holder may be a holder part formed integrally with the housing without being provided independently of the housing of the apparatus. Further, the position adjustment of the optical element may be performed not only in the main scanning direction but also in other directions.

  As described above, the present invention is useful for an optical scanning optical device, and is particularly excellent in that deterioration of optical performance during thermal deformation can be suppressed as much as possible.

DESCRIPTION OF SYMBOLS 1 ... Laser diode 11, 12, 13 ... Scanning lens 13a ... Mounting reference surface 30 ... Lens holder 31, 32, 33 ... Positioning seat surface 34, 35, 36 ... Adhesion seat surface 36a ... Restriction part 40 ... Filling space 40a ... Filling Port 45 ... Screw member 50 ... Adhesive Y ... Main scanning direction

Claims (4)

In an optical scanning optical device that deflects and scans light emitted from a light source in a main scanning direction by a predetermined optical element,
An elongated optical element extending in the main scanning direction and having a flat mounting reference surface on one surface;
An element having an adhesive seating surface for forming a filling space between a positioning seating surface for holding the mounting reference surface of the optical element on at least three points on a plane and the mounting reference surface for filling with an adhesive. A holder,
An elastic member that elastically presses the mounting reference surface of the optical element onto the positioning seating surface of the element holder;
An adjustment member for adjusting the position of the optical element on the positioning seating surface of the element holder;
With
The filling space has a substantially symmetrical shape with respect to the central axis in the main scanning direction,
After adjusting the position of the optical element with the adjusting member, the filling space was filled with an adhesive and cured,
An optical scanning optical device.   The optical scanning optical device according to claim 1, wherein the adhesive is an ultraviolet curable type or a visible light curable type.   3. The optical scanning optical device according to claim 1, wherein a filling port for filling an adhesive is formed in the adhesive seating surface.   The adhesive seating surface has a restricting portion that restricts movement of the filled adhesive, and the restricting portion extends in substantially the same direction as the direction in which the optical element or the element holder thermally expands, The optical scanning optical device according to claim 1, wherein

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