JP2001166238A - Scanning optical device - Google Patents

Abstract

(57) [PROBLEMS] To reduce the manufacturing cost by forming a stop for limiting the cross-sectional shape of a light beam on a scanning lens locking member. A pressing spring (15) moves a scanning lens (16) to a frame (2).
The scanning lens 16 is held in position by holding the scanning lens 16 so as to be pressed against the seating surfaces T1 and T2. Also,
The presser spring 15 is assembled to the frame 21 by two spring mechanisms. The holding spring 15 is the cylinder lens 1
The aperture 13 is extended to a position connecting the polygon mirror 2 and the polygon mirror 14b, and an aperture 13 is formed at a position intersecting the optical axis L of the laser beam. The holding spring 15 is the scanning lens 1
6 is designed such that the center of the aperture 13 coincides with the optical axis L of the laser beam in a state where the laser beam 6 is locked and assembled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device used for an image forming apparatus such as a laser beam printer and a digital copying machine.

[0002]

2. Description of the Related Art FIG. 15 is a partial plan view of a conventional scanning optical device. A cylinder lens 1, an aperture plate 2, and a polygon mirror 3 are arranged on an optical axis L of a laser beam from a semiconductor laser light source (not shown). The scanning lenses 4 and the like are arranged in the direction of reflection of the polygon mirror 3, and these members are fixed on a frame 5.

A laser beam emitted from a semiconductor laser light source is shaped into an elliptical shape with a limited beam cross-sectional shape determined by an opening 2 a of an aperture plate 2.
This light beam is deflected by the polygon mirror 3 and is scanned as a beam spot on the surface of the photosensitive drum through the scanning lens 4.

The aperture plate 2 is made elliptical or circular in order to suppress a side rope in a beam spot on the photosensitive drum surface, and is located before and after the collimator lens.
Often incorporated into a light source unit. But,
A scanning optical system arranged between the cylinder lens 1 and the polygon mirror 3 has been devised in order to suppress variations in the reflection position of the laser beam on the surface of the polygon mirror 3 and stabilize the printing quality.

FIGS. 16 and 17 are side views of FIG. 15 viewed from the directions A1 and A2, respectively, and FIG.
FIG. 5 is a cross-sectional view taken along line BB of FIG. 5 and shows an assembled state of the scanning lens 4. The aperture plate 2 is disposed on the upper surface of the frame 5 and fixed with screws 2b or the like such that the center of the elliptical or circular opening 2a coincides with the optical axis L from the cylinder lens 1 to the polygon mirror 3. I have. Also,
In order to prevent the reflected light from the surface of the aperture plate 2 from returning to the light source side, the surface facing the laser beam may be inclined, and a hole of the aperture plate 2 is formed in a boss 5 a formed in the frame 5. Are fitted to each other to provide positional accuracy.

The scanning lens 4 is locked at both ends in the longitudinal direction at the outside of the scanning angle range, and is provided on a frame 5 having a high surface accuracy provided on a frame 5 for maintaining the position and the posture. It is fixed by the fixing bracket 6 so as to be pressed against the surfaces T1 and T2.

[0007] The seating surfaces T1 and T2 of the frame 5 are integrally formed using a mold by an injection molding machine if the frame 5 is a resin molded product. The seating surface T1 for determining the attitude of the scanning lens 4 is formed so as to be perpendicular to the scanning plane. In this case, in order to suppress an assembly error in determining the attitude of the scanning lens 4, the seating surface T1 is used. Should be as long as possible. Specifically, by making the length of the portion of the scanning lens 4 abutting on the seating surface T1 close to the dimension in the short direction, the lens size is utilized to the maximum. As described above, by increasing the length of the seating surface T1, it is possible to suppress a tilt angle error of the laser beam of the scanning lens 4 with respect to the scanning surface. Further, the scanning lens 4 is provided with a pressing portion S provided on the fixture 6.
The position and posture of the scanning lens 4 are accurately held by being pressed against the seating surfaces T1 and T2 by S1 and S2.

[0008] The cylinder lens 1 is fixed between the light source unit and the polygon mirror 3 after the focus is adjusted on a seating surface T3 having high surface accuracy. Note that another optical member such as a diffraction grating may be used instead of the cylinder lens 1. The upper opening of the frame 5 is sealed with a lid (not shown) after all necessary members are incorporated into the frame 5.

[0009]

However, in the above-mentioned prior art, the aperture plate 2 having the opening 2a needs to be separately assembled to the frame 5 as an independent member, so that the number of members increases and the cost increases. Therefore, there is a problem in that the number of steps is increased, the assembly cost is increased, and as a result, the manufacturing cost is increased.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a scanning optical device in which manufacturing cost is suppressed by providing a stop for limiting a cross-sectional shape of a light beam also as a member having another function.

[0011]

In order to achieve the above object, a scanning optical apparatus according to the present invention comprises: a light emitting means having a light source for emitting a light beam; a deflection scanning means for deflecting and scanning the light beam; Means for deforming a light beam cross-sectional shape disposed in the optical path of the light beam between the means and the deflection scanning means, and a frame for accommodating these members to limit the cross-sectional shape of the light beam The stop is formed integrally with the scanning lens locking member.

Further, the scanning optical device according to the present invention includes a light emitting means having a light source for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and the light between the light emitting means and the deflection scanning means. Beam scanning means for deforming a cross-sectional shape of the light beam disposed in the optical path of the beam; and a frame accommodating these members, wherein a stop for limiting the cross-sectional shape of the light beam is formed in the scanning lens. And

[0013] The scanning optical device according to the present invention comprises a light emitting means having a light source for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and a light beam between the light emitting means and the deflection scanning means. A beam deforming means for deforming the cross-sectional shape of the light beam disposed in the optical path; and a frame accommodating these members, wherein a diaphragm for limiting the cross-sectional shape of the light beam is formed in the beam deforming means. And

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a plan view of the scanning optical device according to the first embodiment. Reference numeral 11 denotes a light source unit in which a semiconductor laser light source 11a, a collimator lens 11b, and the like are unitized, and the laser beam is compressed in the sub-scanning direction, that is, in the direction perpendicular to the deflection scanning plane, along the optical path of the laser beam emitted from the light source unit 11. Lens 12, aperture 13 and light source unit 1 for forming an image by
Polygon mirror 14b rotated by a motor 14a to deflect and scan the laser beam emitted from
And a deflection scanning unit 14 in which these are unitized. An aperture 13 is provided at one end to form an image of the laser beam that has been deflected and scanned on a photosensitive drum (not shown) and to keep the scanning speed of the laser beam on the surface of the photosensitive drum constant. A first scanning lens 16 fixed by a holding spring 15 having
The second scanning lens 17 and the folding mirror 18 are arranged. In addition, a reflection mirror 19 is disposed to detect a part of the laser beam, and a light detection unit 20 in which a lens and a sensor are unitized is provided in the reflection direction. Then, the cylinder lens 12, the deflection scanning unit 14, the scanning lenses 16, 17, the folding mirror 18,
The reflection mirror 19 and the light detection unit 20 are assembled to the frame body 21 and locked by screws or other fixing means. In addition, the folding mirror 18 below the frame 21
Is provided in the direction of reflection of the laser beam.

With such a configuration, the laser beam emitted from the semiconductor laser light source 11a is
2. Polygon mirror 1 that rotates through aperture 13
The light is reflected by 4b, passes through the scanning lenses 16 and 17, and the turning mirror 18, is irradiated from the emission port 22 of the frame 21 toward the photosensitive drum, and a latent image is formed on the photosensitive body. On the other hand, before being irradiated on the photosensitive drum, a part of the laser beam is
And the light is guided to the light detection unit 20, and the recording start timing is determined by the electric signal taken out therefrom. The image forming apparatus receives the extracted electric signal and forms an image in conjunction with the scanning optical device.

FIG. 2 is a plan view of an aperture portion, and FIG.
4 is a front view in the C2 direction, and FIG. 5 is a side view in the D direction. A holding spring 15 for fixing the scanning lens 16 is formed integrally with the aperture 13. The holding spring 15 is extended to a position connecting the cylinder lens 12 and the polygon mirror 14b, and is provided at a position intersecting the optical axis L of the laser beam. 13 are formed. The center of the aperture 13 coincides with the optical axis L of the laser beam in a state where the presser spring 15 is engaged with the rising portion of the frame 21 by pressing the scanning lens 16 by its elastic force so as to be pressed. It is designed to have such dimensions.

The aperture 13 formed in the presser spring 15 has an elliptical or circular shape, and has a function of shaping the spot on the photosensitive drum surface into an elliptical shape by limiting the cross-sectional shape of the laser beam. ing.
Further, a scanning optical system using a plurality of laser beam light sources has a function of stabilizing printing quality by making the reflection positions of the plurality of laser beams on the surface of the polygon mirror 14b close.

The scanning lens 16 is set in contact with the seating surfaces T1 and T2 formed on the frame body 21. Of the locking portions at both ends, the locking portion closer to the cylinder lens 12 integrates the aperture 13. It is locked by the holding spring 15. The pressing spring 15 locks the scanning lens 16 so as to press the scanning lens 16 against the bearing surfaces T1 and T2 of the frame body 21 to maintain the position and the posture of the scanning lens 16.

Further, the pressing spring 15 is
Assembled by the leaf spring mechanism at each location. For example, the leaf spring mechanism may be provided at a protruding portion near the aperture 13 or at three or more portions. With such a leaf spring mechanism, since the locking of the scanning lens 16 is completed in one operation, the number of assembly steps can be reduced. Note that a method of assembling by screwing may be used.

FIG. 6 is a plan view of a modification, and FIG. 7 is a front view. A regulating guide groove for improving the positional accuracy is added to the aperture. With a configuration similar to that of the first embodiment, a columnar projection 31 is provided upright on the frame body 21.
A groove 32 for sandwiching the plate surface on which the aperture 13 is formed is provided in the columnar projection 31.

Here, if the height of the columnar projections 31 is adjusted to the lower surface of the horizontal portion of the presser spring 15, the columnar projections 31 can function as columns to suppress the displacement of the aperture 13 in the height direction. it can. Although the columnar protrusions 31 are arranged on only one side, they may be arranged on both sides with the aperture 13 interposed therebetween. In this case, it is possible to further restrict the horizontal displacement of the aperture 13.

Further, as shown in the side view of FIG. 8 and the front view of FIG. 9, a return portion 33 is protruded from the plate surface on which the aperture 13 is formed. 32, the positional accuracy can be further improved by absorbing the play between the plate thickness and the groove width, and at the same time, the vibration of the overhanging portion can be prevented. Position is more stable.

FIG. 10 is a cross-sectional view of another modified example, in which the pressing spring 15 is extended to lower the aperture-forming surface, which hangs downward, down to the horizontal plane of the frame body 21. Suppress height deviation.
In addition, by inserting the convex shape 15a provided at the tip into the hole 21a provided in the frame 21, displacement of the aperture 13 can be suppressed. In addition, a concave shape may be provided at the tip of the aperture forming surface of the pressing spring 15, and a convex shape may be provided on the surface of the frame 21.

As described above, by using the pressing spring 15 of the scanning lens 16 in which the aperture 13 is integrated, the positional accuracy of the aperture portion is improved, and the number of members conventionally used two can be reduced to one. Since the components can be assembled in a single operation, the cost of members can be reduced, the number of assembling steps can be reduced, and the manufacturing cost can be reduced.

FIG. 11 is a plan view of an aperture portion of the second embodiment, in which an aperture is formed in a part of the scanning lens 41. FIG. 12 is a cross-sectional view as viewed from the direction E in FIG. 11, and FIG. 13 is a cross-sectional view along a straight line FF. The scanning lens 41 is locked to a seating surface formed on the frame body 21 by a fixture 42 as in the conventional example. However, in this embodiment, of the locking portions at both ends of the scanning lens 41, the locking portion closer to the cylinder lens 12 is provided at a position extending beyond the optical axis L of the laser beam.

An aperture 43 which is an elliptical or circular opening as shown in FIG. 12 is formed at a position intersecting the optical axis L at a connecting portion 41c connecting the lens portion 41a of the scanning lens 41 and the locking portion 41b. ing. Aperture 43
The opening has a cylindrical shape due to the thickness of the connecting portion 41c of the scanning lens 41, and the cylindrical inner surface 43a has
In order to prevent the laser beam from being reflected and becoming stray light, the shape is inclined so as to have a spread along the beam path. Further, the peripheral portion 43b of the aperture 43 to which the laser beam is irradiated is treated with an anti-reflection film or the like as necessary in order to prevent the laser beam from being reflected and returning to the light source to generate light. Have been. The peripheral portion 43 to which the laser beam is irradiated
b may be inclined with respect to the laser beam.

Further, the locking position of the scanning lens 41 is formed substantially symmetrically on both sides, and the end of the scanning lens 41 on the cylinder lens 12 side is extended beyond the locking portion, so that the optical axis L of the laser beam is The aperture 43 may be provided at a location where the intersection is made.

The scanning lens 41 has a lens portion 4 at its end.
Since the same transmittance as 1a can be expected, a method may be used in which only the necessary portion as the aperture 43 is left without providing an opening, and the other portion is cut off the laser beam to form the aperture 43. That is, the peripheral portion 43b is shielded from light by a coating or etching process, a method of attaching a sheet or a seal, or the like, while leaving an elliptical or circular portion corresponding to the aperture 43.

The scanning lens 41 is originally positioned with high accuracy, and the positional accuracy of the aperture 43 formed in the connecting portion 41c of the scanning lens 41 is maintained, so that a special positioning structure is not required. Further, even when the aperture 43 is formed in the scanning lens 41, it is not necessary to use a separate member, whereby the member cost and the manufacturing cost can be suppressed.

FIG. 14 is a perspective view of a cylinder lens according to the third embodiment. An elliptical or circular aperture 52 is formed on a surface of the cylinder lens 51 intersecting the optical axis L. Although the aperture 52 is provided on the surface of the cylinder lens 51 on the beam exit side, it may be provided on the opposite entrance surface. A portion 52a other than the aperture 52 on the surface on which the aperture 52 is formed is subjected to a coating or etching process or a process of attaching a sheet or a seal so as not to transmit the laser beam.

Since the cylinder lens 51 is mounted on the seat surface with high accuracy in both the height direction and the horizontal direction, the position accuracy of the aperture 52 formed in the cylinder lens 51 is maintained, and a special positioning structure is not required. . Also, when the aperture 52 is formed in the cylinder lens 51, another member having the function of the aperture 52 is not required, and the member cost and the manufacturing cost can be reduced.

[0032]

As described above, in the scanning optical apparatus according to the present invention, since the stop for limiting the cross-sectional shape of the light beam is formed integrally with the scanning lens locking member, a separate aperture member is not required. Material costs and manufacturing costs are reduced, contributing to higher performance and lower cost.

Further, in the scanning optical device according to the present invention, since a stop for limiting the cross-sectional shape of the light beam is formed on the scanning lens, a separate aperture member is not required, and the member cost and the manufacturing cost are suppressed, and the cost is reduced. It can contribute to performance and price reduction.

In the scanning optical apparatus according to the present invention, since the stop having the function of limiting the cross-sectional shape of the light beam is formed in the beam deforming means, a separate aperture member is not required, and the member cost and the manufacturing cost are suppressed. It can contribute to higher performance and lower price.

[Brief description of the drawings]

FIG. 1 is a plan view of a scanning optical device according to a first embodiment.

FIG. 2 is a partial plan view.

FIG. 3 is a side view of an aperture holding spring.

FIG. 4 is a front view of an aperture unit.

FIG. 5 is a side view.

FIG. 6 is a plan view of a modification of the aperture section.

FIG. 7 is a side view.

FIG. 8 is a measurement diagram of another modification of the aperture unit.

FIG. 9 is a front view.

FIG. 10 is a side view of still another modified example of the aperture section.

FIG. 11 is a partial plan view of the second embodiment.

FIG. 12 is a front view of an aperture unit.

FIG. 13 is a side view of an optical path of a laser beam.

FIG. 14 is a perspective view of a cylindrical lens according to a third example.

FIG. 15 is a partial plan view of a conventional example.

FIG. 16 is a front view of an aperture section.

FIG. 17 is a side view.

FIG. 18 is a side view of a scanning lens locking portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Light source unit 12, 51 Cylinder lens 13, 43, 52 Aperture 14 Deflection scanning unit 14b Polygon mirror 15 Pressing spring 16, 17, 41 Scanning lens 20 Light detection unit 21 Frame 31 Columnar projection 32 Groove 33 Return part 42 Fixing bracket

Claims (17)

[Claims] 1. A light emitting means having a light source for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and a light beam cross section arranged in an optical path of the light beam between the light emitting means and the deflection scanning means. A scanning optical system comprising: a beam deforming means for deforming the shape; and a frame for accommodating these members, wherein a stop for limiting a cross-sectional shape of the light beam is formed integrally with the scanning lens locking member. apparatus. 2. The scanning optical device according to claim 1, wherein the scanning lens locking member is a leaf spring. 3. The scanning optical device according to claim 1, wherein a portion of the scanning lens locking member where the stop is formed is engaged with a groove provided in the frame. 4. The scanning optical device according to claim 3, wherein a return portion for engaging with a groove provided in the frame is provided at a portion of the scanning lens locking member where the stop is formed. 5. The scanning optical device according to claim 1, wherein a portion of the scanning lens locking member where the stop is formed abuts against a surface of the frame. 6. A convex-shaped portion and a concave-shaped portion are provided on a portion of the scanning lens locking member where the stop is formed and on the frame.
The scanning optical device according to claim 1, wherein the convex portion is inserted into the concave portion. 7. The scanning optical device according to claim 1, wherein said light emitting means has a light source for emitting a plurality of light beams. 8. The scanning optical device according to claim 1, wherein the stop is arranged between the beam deforming unit and the deflection scanning unit. 9. The scanning optical device according to claim 1, wherein said beam deforming means is a cylinder lens. 10. A light emitting means having a light source for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and a light beam cross section arranged in an optical path of the light beam between the light emitting means and the deflection scanning means. A scanning optical device, comprising: a beam deforming means for deforming a shape; and a frame for accommodating these members, wherein a stop for limiting a cross-sectional shape of the light beam is formed in the scanning lens. 11. The scanning optical device according to claim 10, wherein said light emitting means has a light source for emitting a plurality of light beams. 12. The scanning optical device according to claim 10, wherein the stop is arranged between the beam deforming unit and the deflection scanning unit. 13. The scanning optical device according to claim 10, wherein said beam deforming means is a cylinder lens. 14. A light emitting means having a light source for emitting a light beam, a deflection scanning means for deflecting and scanning the light beam, and a light beam cross section arranged in an optical path of the light beam between the light emitting means and the deflection scanning means. A scanning optical apparatus, comprising: a beam deforming means for deforming a shape; and a frame for accommodating these members, wherein a stop for limiting a cross-sectional shape of the light beam is formed in the beam deforming means. 15. The scanning optical device according to claim 14, wherein said light emitting means has a light source for emitting a plurality of light beams. 16. The scanning optical device according to claim 14, wherein the stop is arranged between the beam deforming unit and the deflection scanning unit. 17. The scanning optical device according to claim 14, wherein said beam deforming means is a cylinder lens.