JP2002098924A - Optical scanning system lens and optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of an abnormal images, even in the case of forming vertical walls at both ends of a lens part so as to reinforce the lens part. SOLUTION: An optical scanning system lens 9 has vertical walls 18 which are formed at both ends of the lens part 16 in the longitudinal direction, to integrally form the lens part 16 to converge scanning light and a reinforcing part 17. When the angle obtained between the optical axis of the lens part 16 and the scanning light at the end part is defined as θ1 and an angle obtained between the optical axis of the lens part 16 and the vertical wall 18 is defined as θ2, a relation is set to be θ1<θ2, or the vertical wall 18 is inclined with respect to a surface perpendicular to a scanning surface in the main scanning direction of a beam. Thus, even in the case that the vertical walls 18 are formed at both ends of the lens part 16 so that the lens part 16 is reinforced by the reinforcing part 17, the scanning light transmitted through the end part of the lens 16 is prevented from entering the inside of an effective scanning area, by being reflected by the vertical wall 18 and also the occurrence of the abnormal image thereby is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an electrophotographic image forming apparatus such as a laser printer, a digital copying machine, and a laser facsimile, and forms an optical scanning system for imaging a beam irradiated from a light source on a surface to be scanned. The present invention relates to a lens and an optical scanning device.

[0002]

2. Description of the Related Art In an optical scanning apparatus in which a beam emitted from a light source is deflected and scanned by a deflector to form an image on a surface to be scanned such as a photosensitive member, the beam spot diameter on the surface to be scanned is stabilized. Ingenuity has been devised. For example, JP
As described in JP-A-33712, between a deflector such as a polygon mirror and a surface to be scanned, an fθ lens that corrects a light beam in a main scanning direction, and a light beam in a sub scanning direction is corrected. A configuration in which a long toroidal lens is disposed is adopted.

Meanwhile, optical scanning lenses such as fθ lenses and toroidal lenses have complicated shapes, and high precision is required to maintain high optical characteristics. It is necessary to prevent the occurrence of distortion and deformation. Since a long toroidal lens has a thin shape in which a beam incident surface side is concave, a demand for preventing distortion and deformation is higher than that of an fθ lens. Glass toroidal lenses have high rigidity, but increase manufacturing costs.

Therefore, as shown in FIG. 7, a lens portion 101 for converging a beam scanned in a predetermined range on a surface to be scanned such as a photoconductor and a reinforcing portion 102 for reinforcing the lens portion 101 are integrated. There has been proposed a toroidal lens 100 made of synthetic resin. In this example, the reinforcement 1
Reference numeral 02 denotes a frame shape that surrounds both sides and both ends in the longitudinal direction of the lens unit 101 when viewed from the beam scanning direction. Here, FIG. 7 is a horizontal sectional view showing a part of the conventional toroidal lens 100 in a section parallel to a beam scanning surface. As described above, since the rigidity increases when the lens portion 102 and the reinforcing portion 102 are integrally molded, it is advantageous in preventing distortion and deformation.

[0005]

Generally, an optical scanning system lens such as an fθ lens or a toroidal lens is required to be as short as possible in the scanning direction in order to reduce the size of the entire optical scanning device. ing. As in the case of the toroidal lens 100 shown in FIG.
3, the optical axis of the lens unit 101 and the lens unit 101
The angle θ1 formed with the scanning light at the end of the lens unit 1 is
When the angle θ2 between the optical axis 01 and the vertical wall 103 is larger than the angle θ2, the scanning light is reflected on the vertical wall 103, and the reflected light increases the amount of light in the effective scanning area, thereby causing an abnormal image.

If the length of the toroidal lens 100 is increased in order to prevent the occurrence of the abnormal image, the size of the optical scanning device increases.

Accordingly, an object of the present invention is to prevent occurrence of an abnormal image even when standing walls are formed at both ends of the lens portion to reinforce the lens portion.

[0008]

According to a first aspect of the present invention, there is provided an optical scanning system lens comprising: a lens portion for converging a beam scanned within a predetermined range on a surface to be scanned; a reinforcing portion for reinforcing the lens portion; An optical axis of the lens unit and an optical axis of the lens unit in an optical scanning system lens in which a standing wall that is a part of the reinforcing unit and protrudes in the beam scanning direction from both ends in the longitudinal direction of the lens unit is integrally formed; The angle θ2 between the optical axis of the lens unit and the upright wall is determined to be larger than the angle θ1 between the scanning light at the end of the lens unit and the vertical axis.

Therefore, it is possible to prevent the scanning light transmitted through the end of the lens portion from being reflected by the vertical wall while satisfying that the distortion and deformation of the optical scanning lens are prevented by the reinforcing portion. Become.

According to a second aspect of the present invention, there is provided an optical scanning system lens comprising a lens portion for converging a beam scanned in a predetermined range on a surface to be scanned, a reinforcing portion for reinforcing the lens portion, and a part of the reinforcing portion. And an upright wall protruding in the beam scanning direction from both ends in the longitudinal direction of the lens unit, wherein the upright wall is a surface perpendicular to a scanning surface in the main scanning direction of the beam. Is inclined with respect to

Therefore, after satisfying that the distortion and deformation of the optical scanning system lens are prevented by the reinforcing portion, even if the scanning light transmitted through the end of the lens portion is reflected by the vertical wall, the reflected light is transmitted by the beam. Can be deflected in the sub-scanning direction away from the scanning surface.

According to a third aspect of the present invention, in the optical scanning lens according to the first or second aspect, the incident side surface of the lens portion is a concave surface serving as a toroidal surface.

Therefore, in the toroidal lens as the optical scanning system lens, the lens portion and the reinforcing portion are formed integrally, and even if it is thin, distortion and deformation are prevented. Further, similarly to the first or second aspect, it is possible to avoid the problem that the scanning light transmitted through the end of the lens portion is reflected on the vertical wall.

According to a fourth aspect of the present invention, there is provided an optical scanning device, wherein the optical scanning system lens according to any one of the first to third aspects is disposed so as to face a surface to be scanned, and the light beam emitted from a light source is scanned by the light scanning system. A deflector for deflecting and scanning toward the system lens.

Therefore, since the lens portion and the reinforcing portion are integrally formed in the optical scanning system lens, distortion and deformation are prevented. Further, it is possible to avoid the adverse effect that the scanning light transmitted through the end of the lens portion is reflected on the standing wall.

[0016]

FIG. 1 shows a first embodiment of the present invention.
A description will be given with reference to FIG. 1 is a perspective view of the optical scanning device, FIG. 2 is a side view of the optical scanning device, FIG. 3 is a plan view of the optical scanning device, and FIG. 4 is a cross-sectional view of a part of the toroidal lens parallel to the beam scanning surface. It is a horizontal sectional view.

As shown in FIGS. 1 to 3, a deflector 3 for deflecting and scanning a beam emitted from a light source (laser emitting portion) 1 and transmitted through a cylindrical lens 2 is provided. The deflector 3 is formed by a motor 4 (see FIG. 2) and a polygon mirror 5 directly connected thereto. The polygon mirror 5 has a plurality of reflection surfaces 6 for deflecting and scanning the beam from the light source 1.

In the optical path between the polygon mirror 5 and the surface to be scanned (photosensitive member) (not shown), an fθ lens 7 as an optical scanning system lens, a folding mirror 8, a toroidal lens 9 as an optical scanning system lens, a folding Mirrors 10, 11
Are sequentially arranged. Further, a pair of synchronous mirrors 12 for reflecting the scanning light reflected from the folding mirror 10 are disposed near both ends of the folding mirror 10, and the scanning mirror 12 receives the scanning light reflected from the synchronous mirror 12 and synchronizes the light. A photodiode 13 that outputs a signal (see FIG. 3) is provided on the synchronization detection plate 14.

A light source 1, a cylindrical lens 2,
Polygon mirror 5, fθ lens 7, folding mirror 8,
10, 11, the toroidal lens 9, the synchronization mirror 12, the synchronization detection plate 14, and the like are provided in a dustproof case (not shown). An opening for emitting the scanning light reflected from the folding mirror 11 toward the surface to be scanned is formed in the dustproof case, and the opening is closed by a transparent dustproof glass 15.

Here, the toroidal lens 9 has a lens portion 16 that is long in the beam scanning direction, a reinforcing portion 17 that reinforces the lens portion 16, and a part of the reinforcing portion 17 that is a longitudinal direction of the lens portion 16. Are formed by integrally resin-molding an upright wall 18 projecting from both ends of the upright in the beam scanning direction and a mounting portion 19 extending outside the upright wall 18. In this example, the mounting portion 19 is the toroidal lens 9.
Is provided inside the above-described dustproof case. The incident surface on the deflector 3 side of the lens portion 16 is a concave surface having a barrel-shaped toroidal surface 16a, and is thin but reinforced by the reinforcing portion 17 as shown in FIG. This reinforcing part 17
Are provided to prevent distortion during molding of the toroidal lens 9 and deformation during assembly, as shown in this example, both sides along the longitudinal direction of the lens portion 16 and both ends in the longitudinal direction of the lens portion 16. Is desirably framed so as to surround the frame from the outside.

Thus, as shown in FIG.
Assuming that the angle between the optical axis 6 and the scanning light at the end of the lens section 16 is θ1, and the angle between the optical axis of the lens section 16 and the standing wall 18 is θ2, the relationship is θ1 <θ2. . In this case, the scanning angle of the beam deflected and scanned by the polygon mirror 5 changes depending on the angle of incidence of the beam from the light source 1 on the polygon mirror 5 and its reflection surface 6, but even if the distance of the toroidal lens 9 to the polygon mirror 5 is changed. The relationship of θ1 <θ2 does not change.

In such a configuration, the beam emitted from the light source 1 is deflected and scanned by a polygon mirror 5 driven to rotate by a motor 4. The beam transmitted through the fθ lens 7 is scanned along the longitudinal direction of the toroidal lens 9. The scanning light transmitted through the end of the toroidal lens 9 in the scanning area is reflected by the folding mirror 10 and the synchronization mirror 12, detected by the photodiode 13 as a synchronization detection signal, and transmitted through the intermediate portion of the toroidal lens 9. Are reflected by the return mirrors 10 and 11 and scanned by the photoconductor.

Here, in FIG. 4, the scanning light transmitted through the end of the lens portion 16 at an angle of θ1 with the optical axis of the toroidal lens 9 is scanning for synchronization detection incident on the photodiode 13. The state where the scanning light is reflected on the standing wall 18 can be avoided. This is due to the setting of θ1 <θ2. Thus, it is possible to prevent the amount of light from becoming abnormally high at the end of the effective scanning area and prevent the occurrence of an abnormal image due to the abnormally high light amount.

Further, reflection of the scanning light into the effective scanning area can be prevented without increasing the length of the lens section 16 in the main scanning direction, which can contribute to downsizing of the optical scanning device. .

Since the standing wall 18 is formed by integrally forming the lens portion 16 and the reinforcing portion 17 as described above, the invention according to claim 1, wherein θ1 <θ2, is set. Is also applicable.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the above embodiment are denoted by the same reference numerals, and description thereof is omitted. FIG. 5 is a rear view of a part of the toroidal lens seen from the scanning light emission surface side, and FIG. 6 is a plan view of a part of the toroidal lens seen from a direction orthogonal to the scanning direction of the scanning light.

This embodiment is an example in which a toroidal lens 20 as an optical scanning system lens is used instead of the toroidal lens 9 in the above embodiment. The toroidal lens 20 is formed by integrally resin molding the lens portion 16, the frame-shaped reinforcing portion 17, the upright wall 18, and the mounting portion 19, similarly to the toroidal lens 9 described above. However, as shown in FIG. 5, the standing wall 18 in the present embodiment is inclined at an angle of θ3 with respect to a plane Y perpendicular to the scanning plane X in the main scanning direction of the beam. This inclination direction is upward in FIG. 5, but may be downward.

In such a configuration, since the toroidal lens 20 has the lens portion 16 and the reinforcing portion 17 integrally formed, distortion and deformation can be prevented. Also,
Even if the scanning light transmitted through the end of the lens unit 16 is reflected by the standing wall 18, the reflected light can be deflected in the sub-scanning direction away from the scanning plane X of the beam. Thus, it is possible to prevent the amount of light from becoming abnormally high at the end of the effective scanning area and prevent the occurrence of an abnormal image due to the abnormally high light amount.

Also in the present embodiment, reflection of scanning light into the effective scanning area can be prevented without increasing the length of the lens section 16 in the main scanning direction. Can contribute.

Since the standing wall 18 is formed by integrally forming the lens portion 16 and the reinforcing portion 17, the standing wall 18 is inclined with respect to a plane Y perpendicular to the scanning plane X in the main scanning direction of the beam. The invention described in claim 2 is also applicable to an fθ lens.

[0031]

According to the optical scanning lens of the first aspect, the lens portion, the reinforcing portion for reinforcing the lens portion, and the beam scanning from both ends of the lens portion in the longitudinal direction of the reinforcing portion. In an optical scanning system lens in which an upright wall protruding in the direction is integrally formed, an angle θ1 between the optical axis of the lens section and the scanning light at the end of the lens section forms an angle between the optical axis of the lens section and the upright wall. Since the angle θ2 is set to a larger value, the condition that the scanning light transmitted through the end of the lens portion is reflected on the vertical wall while satisfying the prevention of distortion and deformation of the optical scanning lens is satisfied. Can be avoided and therefore
It is possible to prevent the amount of light from becoming abnormally high at the end of the effective scanning area and to prevent the occurrence of an abnormal image due to the abnormally high light amount.

According to the optical scanning system lens of the second aspect,
In a light scanning system lens in which a lens portion, a reinforcing portion for reinforcing the lens portion, and a standing wall that is a part of the reinforcing portion and protrudes from both ends in the longitudinal direction of the lens portion in the beam scanning direction are integrally formed, Since the upright wall is inclined with respect to a plane perpendicular to the scanning plane in the main scanning direction of the beam, the end of the lens section is satisfied after satisfying that distortion and deformation of the optical scanning lens are prevented by the reinforcing section. Even if the transmitted scanning light is reflected by the standing wall, the reflected light can be deflected in the sub-scanning direction away from the scanning surface of the beam, so that the amount of light becomes abnormally high at the end of the effective scanning area.
Further, it is possible to prevent occurrence of an abnormal image caused by the above.

According to the third aspect of the present invention, in the optical scanning lens according to the first or second aspect, the incident side surface of the lens portion is a concave surface serving as a toroidal surface. In the lens, the lens portion and the reinforcing portion are integrally formed, so that even if the lens is thin, distortion and deformation can be prevented, and furthermore, as in the first or second aspect, the lens portion is transmitted through the end portion. It is possible to avoid the adverse effect that the scanning light is reflected on the standing wall and prevent the occurrence of an abnormal image.

According to a fourth aspect of the present invention, an optical scanning system lens according to any one of the first to third aspects is disposed so as to face the surface to be scanned, and the light emitted from the light source is emitted by the light scanning system. And a deflector that deflects and scans toward the scanning lens, so that the scanning light passing through the end of the lens unit is satisfied after satisfying that the distortion and deformation of the optical scanning lens are prevented by the reinforcing unit. An adverse image reflected on the standing wall can be avoided to prevent occurrence of an abnormal image.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical scanning device according to a first embodiment of the present invention.

FIG. 2 is a side view of the optical scanning device.

FIG. 3 is a plan view of the optical scanning device.

FIG. 4 is a horizontal sectional view showing a part of the toroidal lens in a section parallel to a beam scanning surface.

FIG. 5 is a rear view of a part of the toroidal lens according to the second embodiment of the present invention as viewed from a scanning light emitting surface side.

FIG. 6 is a plan view of a part of the toroidal lens viewed from a direction orthogonal to a scanning direction of scanning light.

FIG. 7 is a horizontal sectional view showing a part of a conventional toroidal lens in a section parallel to a beam scanning surface.

[Explanation of symbols]

 Reference Signs List 1 light source 3 deflector 9 optical scanning system lens 16 lens unit 16a toroidal surface 17 reinforcing unit 18 standing wall 20 optical scanning system lens X scanning surface Y perpendicular surface

Claims (4)

[Claims] 1. A lens section for converging a beam scanned in a predetermined range on a surface to be scanned, a reinforcing section for reinforcing the lens section, and a part of the reinforcing section and a longitudinal direction of the lens section. An optical scanning system lens integrally formed with standing walls protruding in the scanning direction of the beam from both ends of the lens, wherein an angle θ1 between an optical axis of the lens unit and scanning light at an end of the lens unit is determined by an angle θ1. An angle θ2 between the optical axis of the portion and the upright wall is set to a larger value. 2. A lens portion for converging a beam scanned in a predetermined range on a surface to be scanned, a reinforcing portion for reinforcing the lens portion, and a part of the reinforcing portion and a longitudinal direction of the lens portion. An upright wall protruding from both ends of the beam in the scanning direction of the beam, wherein the upright wall is inclined with respect to a plane perpendicular to a scanning surface in the main scanning direction of the beam. An optical scanning system lens characterized by the above-mentioned. 3. The incident surface of the lens section is a concave surface serving as a toroidal surface.
The optical scanning system lens according to the above. 4. The device according to claim 1, wherein the device is arranged to face the surface to be scanned.
An optical scanning device, comprising: the optical scanning system lens according to any one of claims 3 to 3; and a deflector that deflects and scans a beam emitted from a light source toward the optical scanning system lens.