JPS6167819A - Semiconductor laser light scanner - Google Patents

Abstract

PURPOSE:To attain highly accurate scanning by forming a means for scanning laser light and detecting its speed variation and a means for relatively moving a laser and a collimator lens in accordance with the detected result. CONSTITUTION:In a constitution consisting of a semiconductor laser 8, a rotary polyhedral mirror 10 and a photosensitive body 12, the positional shift of a scanning line in the arrow F direction is found out on the basis of the variation of the turning speed of the mirror 10 in the arrow E direction which is detected by a detector 15 and the collimator lens 9 is moved in the arrow G direction by a moving device 16 in accordance with the positional shift value to compensate the shift value. Therefore, the uneven scanning of the laser light which may be generated due to the speed variation of a laser light canning means is compensated to execute highly accurate scanning and the relative movement of the laser and the collimator lens can be accurately attained by using the moving means 16 having an electrostrictive effect as an optical system moving means.

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 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 compact 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. There is.

In the following, 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. FIG. 1 is a perspective view of a conventional semiconductor laser beam printer, in which 1 is a semiconductor laser, 2
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 3 in the direction indicated by the arrow in the figure, the parallel laser beam is scanned in the direction indicated by the arrow B in the figure, and is further imaged onto the photoreceptor 5 by the fθ lens 4, so that the parallel laser beam is scanned in the direction indicated by the arrow C in the figure. Scan at a constant speed in the direction. 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 A, and synchronizes scanning with respect to the rotational direction of the photoreceptor 60.

However, in the above configuration, the laser beam scanning line recorded on the photoreceptor S becomes uneven in the direction of the arrow C in the figure due to fluctuations in the rotational speed of the rotating polygon mirror 3 in the direction of the arrow in the figure. As a result, there was a problem in that the image quality deteriorated.

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 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 a laser that scans the laser light in a first direction. a light scanning means; a speed fluctuation detection means for detecting a speed fluctuation in the first direction of the scanning of the laser beam; and an optical system moving means for relatively moving the collimating lens in a direction corresponding to the first direction, thereby correcting unevenness in laser beam scanning and achieving highly accurate scanning. It is something to do.

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, 13 is a synchronization detection device, 14 is a semiconductor laser drive device, 16 is a rotating polygon mirror rotation speed fluctuation detection device,
16 is a remote lens moving device.

The operation of the semiconductor laser beam printer of this embodiment configured as described above will be described below. However, 8~
140 The basic operations are the same as the operations 1 to 1A in FIG. 1, so the explanation will be omitted.

The rotating polygon mirror rotation speed fluctuation detection device 1S is a rotating polygon mirror 1.
The rotational speed fluctuation of o in the direction of arrow E in the figure is detected. The amount of positional deviation of the scanning line in the direction of arrow F in the figure is determined from the detected rotational speed fluctuation. The collimating lens moving device 16 moves the collimating lens 9 according to the detected positional deviation amount.
is moved in the direction of arrow G in the figure to correct the positional deviation.

The extent to which the deviation of the scanning line can be corrected by moving the collimating lens will be explained with reference to FIG. FIG. 3 is a front view of a semiconductor laser beam printer according to an embodiment of the present invention, in which 17 is a semiconductor laser, 18 is a collimating lens, 19 is an fθ lens, 20 is a laser beam imaging line, and 21 is an fθ lens 19. is the optical axis of 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 inclination of the laser beam after passing through the collimating lens 18 and the optical axis 21, b is the amount of deviation between the imaging point and the optical axis 21, fl and f2 are the focal lengths of the collimating lens 18 and fθ lens 19, respectively, and arrow H in the figure is an arrow indicating a direction corresponding to arrows F and G in FIG. From FIG. 3, θ can be determined by the following formula.

θ; a/f1 (1) From the characteristics of fθ lens, b; f2θ (2) (1), (2
) From the formula, the amount of deviation of the scanning line is usually about 5626 μm (4), and as an optical system, f = 10 pieces (5) f = 250
Translation: Designed to the extent of (6).

Substituting equations (4) to (6) into the (Shizu equation), 661 μm
...(7) is obtained, collimating lens 1
It can be seen that it is possible to correct the amount of deviation of the laser beam scanning line by only slightly displacing 8.

In addition, 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 displacements as expressed by equation (7) with a simple configuration. .

Effects of the Invention As is clear from the above description, the semiconductor laser beam scanning device according to the present invention includes a semiconductor laser serving as a light source, a collimating lens that converts the laser beam emitted by the semiconductor laser into a parallel laser beam, and a first direction parallel laser beam. a laser beam scanning means for scanning the laser beam with the laser beam; a speed fluctuation detecting means for detecting a speed fluctuation in the first direction of the scanning of the laser beam; The device is configured to include an optical system moving means for relatively moving the semiconductor laser and the collimating lens in a direction corresponding to the first direction in accordance with speed fluctuations. The excellent effect of correcting the scanning unevenness of the laser beam caused by speed fluctuations of the scanning means and performing highly accurate scanning can be obtained.

Furthermore, 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 precision 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 plan view of a semiconductor laser beam printer according to an embodiment of the present invention. 8.17... Semiconductor laser, 9,18...
...Collimating lens, 1Q...Rotating polygon mirror,
1S...Rotating polygon mirror rotation speed fluctuation detection device. 1
e... Collimator lens moving device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure H1

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
a speed fluctuation detection means for detecting speed fluctuation in the direction; and a speed fluctuation detection means for detecting speed fluctuation in the direction of the semiconductor laser and the collimating lens relative to the first direction in accordance with the speed fluctuation detected by the speed fluctuation detection means. 1. A semiconductor laser beam scanning device comprising: an optical system moving means for moving an optical system. (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.