JPS6167817A - Semiconductor laser light scanner - Google Patents

Abstract

PURPOSE:To compensate the scanning shift value of laser light scanning and to attain highly accurate scanning by moving a semiconductor laser and a collimator lens in accordance with the detected scanning shift value. CONSTITUTION:Light from the semiconductor laser 8 is collimated by the collimator lens 9 and the parallel light is scanned by the rotation of a rotary polyhedral mirror 10 and formed at its image on a photosensitive body 12 by an ftheta lens 11 to scan the photosensitive body 12 at a constant speed. A part of the laser light is formed on the photodetecting surface of a synchronization detecter 13, which applies a write starting signal in each scanning line to a semiconductor laser driving device 14 to synchronize the scanning as to the turning direction of the photosensitive body 12. The scanning line on the photosensitive body 12 is shifted in the H direction by the turn or the like of respective reflecting surfaces of the mirror 10 in the G direction, the shift is detected by a device 15 and a moving device 16 moves the lens 9 in the J direction in accordance with the detected shift value to compensate the shift value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor laser beam scanning device used in semiconductor laser beam printers and the like.

Conventional Structures and Their Problems In recent years, as semiconductor technology has progressed, semiconductor lasers have become more reliable and cheaper year by year. In addition, semiconductor lasers are small and can be directly modulated, so their field of use is rapidly expanding, and semiconductor laser beam scanning devices are also required to have even higher precision. ing.

Hereinafter, a semiconductor laser beam printer will be explained as a typical example using a semiconductor laser beam scanning device.

A conventional semiconductor laser beam printer will be described below with reference to the drawings. Figure 1 is a perspective view of a conventional semiconductor laser beam printer.
3 is a collimating lens, 3 is a rotating polygon mirror, 4 is an fθ lens, 5 is a photoreceptor, 6 is a synchronization detection device, and 7 is a semiconductor laser drive device.

The operation of the semiconductor laser beam printer configured as above will be described below. A laser beam emitted from a semiconductor laser 1 is converted into a parallel laser beam by a collimating lens 2, and is incident on a rotating polygon mirror 3. By rotating the rotating polygon mirror 30 in the direction of the arrow in the figure, the parallel laser beam is scanned in the direction of the arrow B in the figure, and is further imaged onto the photoconductor 6 by the fθ lens 4, and then scanned on the photoconductor 6 in the direction of the arrow C in the figure. Scan at a constant speed. Further, by rotating the photoreceptor 6 in the direction indicated by the arrow in the figure, a plane scan is performed on the photoreceptor 5.

A portion of the laser light forms an image on the light receiving surface of the synchronization detection device 6.

The synchronization detection device 6 provides a write start signal for each -scanning line to the semiconductor laser drive device 7, and synchronizes scanning with respect to the rotational direction of the photoreceptor 60.

However, in the above configuration, there is a problem that the laser scanning light is shifted in the F direction on the photoreceptor S due to the tilting of each mirror surface of the rotating polygon mirror 3 in the direction of the arrow E in the figure, resulting in a decrease in image quality. Was.

OBJECTS OF THE INVENTION An object of the present invention is to provide a semiconductor laser beam scanning device that enables highly accurate scanning.

Structure of the Invention A semiconductor laser beam scanning device of the present invention includes a semiconductor laser serving as a light source, a collimating lens that converts laser light emitted by the semiconductor laser into parallel laser light, and scanning the laser light in a first direction. a laser beam scanning means for performing the scanning;
a scanning deviation amount detection means for detecting a scanning deviation amount in a second direction that is not parallel to the first direction of the scanning of the laser beam, and according to the scanning deviation amount detected by the scanning deviation amount detection means, The device may be configured to include an optical system moving means for relatively moving the semiconductor laser, the collimator, and the lens in a direction corresponding to the first direction. The system corrects this and performs highly accurate scanning.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view of a semiconductor laser beam printer according to an embodiment of the present invention, in which 8 is a semiconductor laser, 9 is a collimating lens, 1o is a rotating polygon mirror, 11 is an fθ lens, 12 is a photoreceptor, and 13 is a 14 is a semiconductor laser drive device, 16 is a scanning deviation amount detection device, and 16 is a collimating lens moving device.

The operation of the semiconductor laser beam printer of this embodiment configured as described above will be described below. However, 8~
The basic operations of 14 are the same as those of 1 to 7 in FIG. 1, so their explanation will be omitted. The scanning line of the laser beam on 12 is indicated by arrow H in the figure.
direction. The scanning deviation amount detection device 16 detects this deviation amount. According to the detected amount of deviation, the collimating lens moving device 16 moves the collimating lens 9 in the direction of arrow J in the figure to correct the amount of deviation.

The extent to which the shift in the scanning line can be corrected by moving the collimating lens 9 will be explained with reference to FIG. Third
The figure is a front view of a semiconductor laser beam printer in an embodiment of the present invention.

17 is a semiconductor laser, 18 is a collimating lens, 19 is an fθ lens, 2o is a laser beam imaging line, and 21 is an optical axis of the fθ lens 19. Further, the light emitting point of the semiconductor laser 17 is located on the optical axis of the fθ lens 19. Furthermore, in FIG. 3, a is the amount of deviation between the optical axis of the collimating lens 18 and the optical axis 21 of the fθ lens 19, and θ is the amount of deviation between the optical axis of the collimating lens 18 and the optical axis 21 of the fθ lens 19.
8 is the inclination of the laser beam and the optical axis 21, b is the amount of deviation between the imaging point and the optical axis 21, f', and f2 are the focal lengths of the collimating lens 18 and fθ lens 19, respectively, and are indicated by the arrows in the figure. is an arrow indicating a direction corresponding to arrows H and J in FIG. From FIG. 3, θ can be determined by the following formula.

θ=a/f, ・・・・・・(1
) From the characteristics of the fθ lens, b = f2θ ・River... (2) (1
), From formula (2), fl & =-b...
... (3) The amount of deviation of the scanning line is usually about 5626 μm ... (4) and as an optical system, f, = 10 order - Old ... (6) f2
=260ytpr (6
) is designed to a certain degree.

Substituting equations (4) to (6) into equation (3), a≦1μm
. . . (7) is obtained, and it can be seen that the amount of deviation of the laser beam scanning line can be corrected by only slightly displacing the collimating lens 18.

However, since the collimating lens moving device 16 shown in FIG. 2 is constructed using a material that has an electrostrictive effect, it is possible to accurately realize minute displacement as expressed by equation (7) with a simple configuration. .

Effects of the Invention As is clear from the above description, the semiconductor laser scanning device according to the present invention includes a semiconductor laser serving as a light source, a collimating lens that transforms the laser light emitted by the semiconductor laser into parallel laser X laser light, and a first direction. a scanning deviation amount detection means for detecting a scanning deviation amount in a second direction not parallel to the first direction of the scanning of the laser beam; Optical system moving means for relatively moving the semiconductor laser and the collimating lens in a direction corresponding to the first direction according to the scanning deviation amount detected by the scanning deviation amount detection means. Therefore, the excellent effect of correcting the amount of scanning deviation of the laser scanning light and performing highly accurate scanning can be obtained.

Further, by using a member having an electrostrictive effect in the optical system moving means, it is possible to achieve the effect that relative movement between the semiconductor laser and the collimating lens can be realized with high accuracy with a simple configuration.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a conventional semiconductor laser beam printer.
FIG. 2 is a perspective view of a semiconductor laser beam scanning device according to an embodiment of the present invention, and FIG. 3 is a front view thereof. 8.17... Semiconductor laser, 9,18...
...Collimating lens, 1o...Rotating polygon mirror,
16...Scanning deviation amount detection device, 16...
・Collimator lens moving device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure IK

Claims (2)

[Claims] (1) A semiconductor laser serving as a light source, a collimating lens that converts the laser light emitted by the semiconductor laser into parallel laser light, a laser light scanning unit that scans the laser light in a first direction, and the laser light the first of the scans of
scanning deviation amount detection means for detecting a scanning deviation amount in a second direction that is not parallel to the direction of 1. A semiconductor laser beam scanning device comprising an optical system moving means for moving the optical system relatively in a direction corresponding to the direction. (2) A semiconductor laser beam scanning device according to claim 1, wherein a member having an electrostrictive effect is used for the optical system moving means.