JP4750306B2 - Optical scanning device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical scanning apparatus suitable for a color image forming apparatus such as a laser beam printer having a color electrophotographic process or a color digital copying machine.
[0002]
[Prior art]
In general, a color image forming apparatus records color image information while suppressing a shift in scanning lines between colors, and an optical scanning apparatus usable for this type of color image forming apparatus emits laser light, for example. The optical box includes a light source, a deflection scanning unit that deflects and scans the light beam from the light source, and a scanning lens that scans the light beam deflected and scanned by the deflection scanning unit on the scanning surface of the image carrier at a constant speed. .
[0003]
In such an optical scanning device, when the scanning lens is deformed or its position is decentered, the scanning line that scans the surface to be scanned is bent, or the length in the main scanning direction is the left-right difference. One half magnification will occur. Such bending of scanning lines and single magnification are not a problem when forming monochrome images unless they are extremely large. However, when forming a color image, they are problematic because they overlap a plurality of scanning lines. Will occur. Therefore, in order to form a color image with high definition, it is necessary to reduce the bending of the scanning line and the half magnification, thereby reducing the deviation of the scanning line between the colors.
[0004]
Specifically, each color is superimposed on the surface to be scanned by a combination of a single optical scanning device and a single image carrier. However, when forming a color image, the scanning line of each color is Since the curvature and the habit of half magnification are the same, the color shift can be within a certain range.
[0005]
However, when a color image is formed at a high speed by combining a plurality of optical scanning devices and a plurality of image carriers, the position and orientation of the scanning lens can be obtained by simply assembling the scanning lens in an optical box, for example. Variation occurs. Therefore, since the bend of the scanning line of each color and the habit of one magnification are different for each optical scanning device, even if the registration in the sub-scanning direction is combined, the scanning line shifts between the colors, and a high-definition color image Is extremely difficult to form.
[0006]
In view of this, the present applicant has proposed an optical scanning apparatus that addresses the above-mentioned problems in Japanese Patent Application No. 2000-6729. This optical scanning device is configured as shown in FIG. 8, for example, and includes a light source unit 2, a cylindrical lens 3, a polygon mirror 4 and a drive motor 5 in an optical box 1, a deflection scanner 6, a refractive optical element 7, a diffraction optical element. An optical element 8 and the like are arranged. Then, the laser light L emitted from the light source unit 2 is transmitted through the cylindrical lens 3 and condensed linearly on the reflection surface of the polygon mirror 4 of the deflection scanner 6, and is deflected by the reflection surface of the rotating polygon mirror 4. Then, the light passes through the refractive optical element 7 and the diffractive optical element 8 to scan the surface to be scanned of the photosensitive member of the rotary drum 9 which is an image carrier.
[0007]
As shown in FIGS. 9, 10, and 11, the lower surface 8 a of the diffractive optical element 8 is a curved surface, and the optical box 1 includes left and right holding bases 11 for holding the diffractive optical element 8, and these And an adhering base 12 for adhering the diffractive optical element 8. The upper surface of the holding table 11 is a recess 11 a that receives the diffractive optical element 8, and the upper surface of the bonding table 12 is a recess 12 a that receives the diffractive optical element 8.
[0008]
When the diffractive optical element 8 is attached to the optical box 1, after the ultraviolet curable adhesive 13 is applied to the concave portion 12 a of the bonding table 12, the diffractive optical element 8 is bridged over the concave portions 11 a of the left and right holding tables 11. As a result, the gap 13 between the diffractive optical element 8 and the bonding base 12 is filled with the adhesive 13. Then, in order to correct the bend and the half magnification of the scanning line, the diffractive optical element 8 is moved in the A direction and rotated in the B direction to adjust the position and posture of the diffractive optical element 8, and then the ultraviolet rays are bonded. The agent 13 is irradiated to cure it.
[0009]
[Problems to be solved by the invention]
However, in the above-described prior application example , since the bonding table 12 is integrated with the optical box 1, the rigidity of the bonding table 12 is higher than the rigidity of the diffractive optical element 8. Further, when the adhesive 13 is cured, shrinkage stress is generated in the adhesive 13. Therefore, when the adhesive stand 12 is cured and contracted, the diffractive optical element 8 is attracted, and the diffractive optical element 8 whose position and posture are accurately adjusted as shown in FIG. 12 may be deformed to deteriorate the image.
[0010]
On the other hand, in order to reduce the amount of cure shrinkage of the adhesive 13, when the gap 14 between the diffractive optical element 8 and the adhesive base 12 is reduced and the amount of the adhesive 13 is reduced, the adhesive 13 While the amount of cure shrinkage is reduced, the adhesive force of the adhesive 13 is weakened. Accordingly, in this case, it is conceivable that the diffractive optical element 8 is easily detached from the optical box 1 due to an impact or the like, and it becomes impossible to form an image.
[0011]
An object of the present invention is to provide an optical scanning device that can solve the above-described problems and can form a high-definition image without changing a predetermined position and posture of a scanning lens.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a deflection scanning unit that deflects and scans a light beam from a light source, a scanning lens that transmits a light beam deflected and scanned by the deflection scanning unit,
An optical box that houses the deflection scanning means and the scanning lens, a first holding base and a second holding base that respectively hold both ends in the longitudinal direction of the scanning lens, and the first holding base in the longitudinal direction of the scanning lens And a second holding base, and an adhesive portion to which the scanning lens is adhered by an adhesive, and scanning a surface to be scanned with a light beam transmitted through the scanning lens. The adhesive portion is a flexible piece supported in a cantilever shape by the optical box, and is elastically deformed toward the scanning lens side by curing shrinkage of the adhesive.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 is a plan view of the first embodiment, and a light source unit 22 that emits laser light L is attached to an optical box 21. A cylindrical lens 23 and a deflection scanner 24 are sequentially arranged in the traveling direction of the laser light L emitted from the light source unit 22 in the optical box 21. The deflection scanner 24 includes a polygon mirror 25 that deflects the laser beam L, and a drive motor 26 that holds the polygon mirror 25 rotatably in the C direction. In the traveling direction of the laser beam L deflected by the polygon mirror 25, a refractive optical element 27 constituting a refractive part of an fθ lens as a scanning lens and a diffractive optical element 28 constituting a diffractive part of the fθ lens are provided in an optical box 21. The rotary drum 29 that is an image carrier is disposed outside the optical box 21.
[0022]
The laser light L emitted from the light source unit 22 passes through the cylindrical lens 23, is linearly collected on the reflection surface of the polygon mirror 25, and is deflected by the reflection surface of the rotating polygon mirror 25. The deflected laser light L passes through the refractive optical element 27 and the diffractive optical element 28, is emitted from the exit 21a of the optical box 21, forms an image on the photosensitive member on the rotating drum 29, and is the D direction which is the main scanning direction. To scan.
[0023]
Figure 2 is an enlarged perspective view of the diffractive optical element 28 near the front attachment to the optical box 21, the holding base 31 of the left and right for holding longitudinal both end portions of each of the diffractive optical element 28 (first holder and A second holding base) and an adhesive portion 32 for adhering the diffractive optical element 28 located between the holding bases 31 are provided integrally with the optical box 21. On the upper surface of the holding base 31, a substantially V-shaped concave portion 31a for receiving the lower surface 28a having a circular arc shape of the diffractive optical element 28 is formed.
[0024]
Here, the adhesive part 32 has front and rear base parts 33 and 34 having the same height as the holding base 31, and for example, one flexible piece 35 is supported in a cantilever shape on the front base part 33. The flexible piece 35 is formed at a position corresponding to the approximate center of the diffractive optical element 28 in the longitudinal direction. Between the front and rear base parts 33, 34, there is a penetration part 36 in which the three sides of the flexible piece 35 are discontinuous with respect to the optical box 21 and the remaining one side is continuous with the base part 33. Is formed. As a result, the flexible piece 35 is elastically deformable with the base 33 side being a fixed end and the opposite side being a free end.
[0025]
The flexible piece 35 is formed in, for example, a substantially U shape that receives the lower surface 28 a of the diffractive optical element 28, and the left and right base portions 37 and 38 located on both sides of the flexible piece 35 are similar to the flexible piece 35. Substantially U-shaped upper surfaces 37a and 38a are formed. When the diffractive optical element 28 is bridged over the concave portions 31a of the left and right holding bases 31, gaps described later are formed between the lower surface 28a of the diffractive optical element 28 and the upper surfaces 35a, 37a, 38a of the bonding portion 32. It is designed to be provided.
[0026]
3 is a longitudinal sectional view of the diffractive optical element 28 and the vicinity thereof, and FIG. 4 is a transverse sectional view of the optical box 21 in the vicinity of the diffractive optical element 28. When the diffractive optical element 28 is fixed to the optical box 21, First, the ultraviolet curable adhesive 39 is applied only to the upper surface 35 a of the flexible piece 35 of the bonding portion 32, and then the diffractive optical element 28 is bridged between the concave portions 31 a of the left and right holding bases 31. As a result, the gap 39 between the lower surface 28 a of the diffractive optical element 28 and the upper surface 35 a of the flexible piece 35 is filled with the adhesive 39. On the other hand, between the lower surface 28a of the other upper surface 37a, 38 b and the diffractive optical element 28 of the adhesive portion 32 there is a gap in a state where the diffractive optical element 28 floats. In this state, the position and orientation of the diffractive optical element 28 are adjusted by the method described below.
[0027]
FIG. 5 is a plan view showing a method for measuring and adjusting the bending and half magnification of the scanning line. Optical sensors 41, 42 and 43 for detecting the laser beam L are arranged in place of the rotating drum 29, and these lights are arranged. The optical sensor surfaces of the sensors 41, 42, and 43 are disposed at positions corresponding to the scanned surface 29 a of the rotary drum 29.
[0028]
When correcting the half magnification of the scanning line, first, the time for the laser light L to scan between the optical sensor 41 and the optical sensor 42, and the time for the laser light L to scan between the optical sensor 42 and the optical sensor 43, Measure. Next, these times are compared, and the difference between the lengths of the left and right scanning lines with respect to the center of the scanning line in the main scanning direction, that is, the D direction on the scanned surface 29a, that is, the half magnification is obtained. Then, the diffractive optical element 28 is moved in the E direction in FIG. 2 along the longitudinal axis so that the left and right half magnifications are the same.
[0029]
On the other hand, when correcting the bending of the scanning line, line sensors arranged in the height direction of the optical sensors 41, 42, 43 are used, and the height position of the laser light L incident on the optical sensors 41, 42, 43 is used. , And the difference between the height of the laser light L incident on the outer optical sensors 41 and 43 and the height of the laser light L incident on the central optical sensor 42 is measured as the bending of the scanning line. Then, the diffractive optical element 28 is rotated in the direction F in FIG. 2 about the longitudinal axis so that the bending of the scanning line is reduced.
[0030]
In this way, after correcting the single magnification and the bending of the scanning line, when the ultraviolet ray is irradiated onto the adhesive 39 from above the diffractive optical element 28, the adhesive 39 cures and shrinks while the diffractive optical element 28 and the adhesive part 32 are bonded. Glue. At this time, since the flexible piece 35 has a cantilever shape and has a rigidity lower than that of the diffractive optical element 28, the flexible piece 35 is elastically deformed with the fixed end as a fulcrum. That is, as shown in FIG. 6, the flexible piece 35 is elastically deformed from a position having a gap 40 indicated by a broken line to a position having a narrow gap 40 'indicated by a solid line, and the diffractive optical element in which the bending of the scanning line and the half magnification are corrected. 28 predetermined positions and postures are held.
[0031]
As described above, in the first embodiment, since the flexible piece 35 is provided by forming the through portion 36 in the optical box 21, the adhesive 39 between the diffractive optical element 28 and the flexible piece 35 is cured and contracted. At this time, the flexible piece 35 is elastically deformed, and the diffractive optical element 28 is not deformed and its position and posture are not changed. Therefore, the diffractive optical element 28 can be securely fixed to the optical box 21 while maintaining a predetermined position and posture, and a high-definition image can be formed.
[0032]
FIG. 7 is a longitudinal sectional view of the diffractive optical element 28 of the second embodiment and the vicinity thereof, and the flexible piece 35 ′ is entirely thinner than the flexible piece 35 of the first embodiment. . Moreover, the groove 35b is formed in the fixed end of flexible piece 35 ', and the thickness of a fixed end is made thin locally.
[0033]
In the second embodiment, one of the thickness of the flexible piece 35 ′, the size of the groove 35b, the size of the gap 40, the filling amount of the adhesive 39, and the surface area of the flexible piece 35 ′. By combining one or more, it is possible to adjust the rigidity of the flexible piece 35 '. Therefore, the flexible piece 35 'can be deformed so as to be equal to the curing shrinkage amount of the adhesive 39, that is, no stress is applied to the diffractive optical element 28, which is better than that of the first embodiment. Effects can be achieved.
[0034]
In the first and second embodiments described above, the ultraviolet curable adhesive 39 is used, but an adhesive having other characteristics can also be used.
[0035]
【The invention's effect】
As described above, in the optical scanning device according to the present invention, the adhesive portion of the optical box is elastically deformed to the scanning lens side due to curing shrinkage of the adhesive, so that the predetermined position and posture of the scanning lens are not changed. A high-definition image can be formed.
[0036]
In the optical scanning device of the first embodiment, since at least one portion in the vicinity of the center of the scanning lens is adhered, when the scanning lens is thermally expanded, the right and left stretching amounts are uniform, and the scanning line is single-magnification. Can be made uniform.
[0037]
In the optical scanning device according to the first embodiment , since the penetration portion is formed so that a part of the adhesion portion is a fixed end and the other portion is a free end, the adhesion portion has a cantilever shape. And is easily elastically deformed.
[0041]
In the optical scanning device according to the first embodiment , the scanning lens is translated along the longitudinal axis to adjust the half magnification in the main scanning direction on the scanning surface, so that the half magnification is easily adjusted. Thus, the scanning lens can be easily adhered.
[0042]
In the optical scanning device according to the first embodiment, since the scanning lens is rotated around the longitudinal axis to adjust the curvature of the scanning line on the surface to be scanned, the curvature of the scanning line is easily adjusted. Thus, the scanning lens can be easily adhered.
[0043]
In the optical scanning device according to the first embodiment, since the scanning lens is a diffractive optical element, the scanning line is suppressed while suppressing deterioration in optical performance such as a spot diameter as compared with a refractive optical element. Can be corrected with higher accuracy.
[Brief description of the drawings]
FIG. 1 is a plan view of a first embodiment.
FIG. 2 is an enlarged perspective view of a diffractive optical element and its vicinity before being attached to an optical box.
FIG. 3 is a longitudinal sectional view of a diffractive optical element and its vicinity.
FIG. 4 is a cross-sectional view of an optical box in the vicinity of a diffractive optical element.
FIG. 5 is an explanatory diagram of measurement of scanning line bending and half magnification.
FIG. 6 is an explanatory diagram of the operation of a flexible piece.
FIG. 7 is a longitudinal sectional view of a diffractive optical element according to a second embodiment and the vicinity thereof.
FIG. 8 is a plan view of a prior application example .
FIG. 9 is a longitudinal sectional view of the diffractive optical element of the prior application example and the vicinity thereof.
FIG. 10 is a cross-sectional view of an optical box in the vicinity of the diffractive optical element of the prior application example .
FIG. 11 is an explanatory diagram of a method for attaching a scanning lens according to a prior application example .
FIG. 12 is an operation explanatory diagram of a prior application example .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 21 Optical box 22 Light source unit 24 Deflection scanner 27 Refractive optical element 28 Diffractive optical element 28a Lower surface 29 Rotating drum 29a Surface to be scanned 31 Holding stand 32 Adhesion part 33, 34, 37, 38 Base part 35, 35 'Flexible piece 35a , 37a, 38a surface 35b groove 36 penetrating portion 39 adhesive 40, 40 ′ gap

Claims (5)

Deflection scanning means for deflecting and scanning a light beam from a light source;
A scanning lens for light flux deflected and scanned by said deflection scanning means is transmitted,
An optical box for accommodating the deflection scanning means and the scanning lens;
A first holding table and a second holding table that respectively hold both ends in the longitudinal direction of the scanning lens;
An adhesive portion located between the first holding base and the second holding base in the longitudinal direction of the scanning lens, and the scanning lens being bonded by an adhesive;
The optical scanning apparatus for scanning a scanned surface upper Yu, and the light beam transmitted through the scanning lens,
The optical scanning device according to claim 1, wherein the adhesive portion is a flexible piece supported in a cantilever shape by the optical box, and is elastically deformed toward the scanning lens side by curing shrinkage of the adhesive. The flexible piece, wherein the first holder and the second holder includes an optical scanning apparatus according to claim 1, characterized in that provided in the optical box and integral. Deflection scanning means for deflecting and scanning a light beam from a light source;
A scanning lens through which the light beam deflected and scanned by the deflection scanning means passes;
An optical box for accommodating the deflection scanning means and the scanning lens;
A first holding table and a second holding table that respectively support the longitudinal ends of the scanning lens;
An adhesive portion located between the first holding base and the second holding base in the longitudinal direction of the scanning lens, and the scanning lens being bonded by an adhesive;
An optical scanning device that scans the surface to be scanned with a light beam transmitted through the scanning lens,
The rigidity of the adhesive part in the direction in which the scanning lens and the adhesive part are aligned is lower than the rigidity of the scanning lens so that the adhesive part is elastically deformed to the scanning lens side by curing shrinkage of the adhesive. Optical scanning device. The first holder, the lower surface of the front Symbol Scanning lens facing the second holder and the bonded joints, cross section seen from the longitudinal direction of the scanning lens is a plane is a circular arc shape,
The first holder and a portion facing the second holder of the scanning lens has a recess for receiving the lower surface of the scanning lens, respectively,
Said opposed portions to said scanning lens bonding portion includes an optical scanning apparatus according to any one of claims 1 to 3, characterized in that a substantially U-shaped to receive the lower surface arc-shaped of the scanning lens .   The optical scanning device according to claim 1, wherein the scanning lens is a diffractive optical element.

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