JP2995108B2 - Scanning optical device - Google Patents

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 for forming an image on a surface to be scanned by laser light from a semiconductor laser modulated by an image signal.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view of a conventional scanning optical device, and FIG. 6 is a diagram showing a semiconductor laser 1 and a collimating lens 3 shown in FIG.
FIG.

[0003] This scanning optical device comprises a semiconductor laser 1
, Collimating optical system, rotating polygon mirror 5 and imaging lens 6
And the photoconductor 7. The semiconductor laser 1 is fixed to the laser base 14, the laser chip 8 and the photodiode cell 10 installed in the laser base 14, and the emission direction of laser light output from the laser chip 8. It consists of a laser window 9. The collimating optical system includes a collimating lens 3 and a collimating lens aperture 13.
And a cylindrical lens 4.

A laser beam from a semiconductor laser 1 modulated by an image signal obtained by exposing and scanning an original image is collimated by a collimating optical system, and is incident on a rotary polygon mirror 5. Laser light for each scanning unit time passes through the rotating polygon mirror 5 and passes through the imaging lens 6 to form an image on the photoconductor 7, and an image is formed by continuing scanning.

[0005]

In the above-described conventional scanning optical device, light from the back surface of the laser chip 8 is diffused by the laser base 14 as shown in FIG. Since the light passes through the laser window 9 and passes through the collimating optical system and is irradiated onto the photoreceptor 7 as disturbance light, there is a disadvantage that the image quality is deteriorated and the high image quality is hindered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a scanning optical device which does not generate disturbance light irradiated on a photosensitive member for imaging by diffused light.

[0007]

According to the scanning optical apparatus of the present invention, light emitted from the back surface of a laser chip of a semiconductor laser is diffused by a laser base, and diffused light passing through a laser window in the laser base is scanned. It has a light shielding member for preventing the light from reaching the surface.

The light shielding member may be provided between the semiconductor laser and the collimating optical system, or may also serve as a stop of the collimating optical system.
Alternatively, it may be provided at a portion of a laser window of a semiconductor laser.

[0009]

By providing a light shielding member for blocking the diffused light passing through the laser window, the diffused light entering the imaging optical system via the rotary polygon mirror is blocked.

[0010]

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

FIG. 1 is an explanatory view of a first embodiment of the scanning optical device of the present invention, and FIG. 2 is a longitudinal sectional view of the semiconductor laser 1 and the collimating optical system shown in FIG.

This scanning optical device comprises a semiconductor laser 1
, A collimating optical system, a scanning optical system, and a photoconductor 7. The semiconductor laser 1 is the same as a conventional scanning optical device, and a laser chip 8 is provided in a laser base 14.
, A photodiode cell 10 and a laser window 9. In the collimating optical system, in addition to the collimating lens 3 and the collimating lens stop 13, the light shielding member 2 of the present invention is provided between the semiconductor laser 1 and the collimating lens 3.

Next, the operation of the scanning optical device will be described.

A laser beam 11, which is an output of the semiconductor laser 1 and modulated by an image signal obtained by exposing and scanning an original image, passes through a laser window 9 and is collimated by a collimating lens 3 to be collimated. , Is incident on a rotating polygon mirror 5 that rotates in only one direction, and the light reflected here is imaged on a photoconductor 7 by an imaging lens 6.
On the other hand, light emitted from the back surface of the laser chip 8 in the semiconductor laser 1 is usually detected by the photodiode cell 10 and used for controlling the amount of laser light. It is diffused by the inner wall, which is generally a metal surface other than the cell 10. Of the diffused light, the diffused light 12 emitted through the laser window 9 is blocked by the light shielding member 2, and the amount of the diffused light that reaches the photoreceptor 7 via the collimating lens 3 and becomes disturbance light is greatly reduced. You.

FIG. 3 is a longitudinal sectional view showing an installation position of a light shielding member 2 of a scanning optical device according to a second embodiment of the present invention.

In this scanning optical device, a collimating lens diaphragm 13 is provided on the side of the semiconductor laser 1 of the collimating lens 3 and is used also as an action of the light shielding member 2, and the diffused light 1 is used.
The aperture is adjusted so as to shield the laser beam 2 and pass only the effective laser beam 11, and no light shielding member is required.

FIG. 4 is a longitudinal sectional view showing an installation position of a light shielding member 2 of a third embodiment of the scanning optical device of the present invention.

In this scanning optical device, the light-shielding member 2 is provided in contact with the laser window 9 of the semiconductor laser 1 on the side of the collimating lens.
Since there is no need to adjust the optical axis, and because it is closer to the laser chip 8, the ratio of blocking the diffused light 12 can be improved.

[0019]

As described above, according to the present invention, a laser beam is converted into parallel light by a collimating optical system, and a scanning optical system scans and forms an image on a surface to be scanned by a rotating polygon mirror and an imaging lens. By providing a light blocking member for blocking the diffused light, the diffused light can be prevented from reaching the photoreceptor as disturbance light, and a good laser spot can be obtained, thereby achieving high image quality. This has the effect.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of a scanning optical device of the present invention.

FIG. 2 is a longitudinal sectional view of the semiconductor laser 1 shown in FIG. 1 and a collimating optical system.

FIG. 3 is a longitudinal sectional view showing an installation position of a light shielding member 2 of a scanning optical device according to a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing an installation position of a light shielding member 2 of a scanning optical device according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a conventional scanning optical device.

6 is a longitudinal sectional view of the semiconductor laser 1 and the collimating lens 3 shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor laser 2 Shielding member 3 Collimating lens 4 Cylindrical lens 5 Rotating polygon mirror 6 Imaging lens 7 Photoreceptor 8 Laser chip 9 Laser window 10 Photodiode cell 11 Laser beam 12 Diffusing light 13 Collimating lens aperture 14 Laser base

Claims (4)

(57) [Claims] A semiconductor laser modulated by an image signal; a collimating optical system for collimating a laser beam output from the semiconductor laser; a deflector for deflecting and scanning the laser beam from the collimating optical system; Forming a laser beam scanned by a deflector on a surface to be scanned;
In a scanning optical device having an imaging optical system, light emitted from the back surface of a laser chip of a semiconductor laser is diffused by a laser base, and diffused light that has passed through a laser window reaches the surface to be scanned. A scanning optical device comprising a light-blocking member for preventing the occurrence of light. 2. The scanning optical system according to claim 1, wherein the light shielding member is provided between the semiconductor laser and the collimating optical system. 3. The scanning optical system device according to claim 2, wherein the light shielding member also serves as a stop of the collimating optical system. 4. The scanning optical device according to claim 2, wherein the light shielding member is provided at a portion of the laser window of the semiconductor laser.