JPS6167818A - Semiconductor laser light scanner - Google Patents

Abstract

PURPOSE:To attain highly accurate scanning by forming a means for detecting the variation of movement of a photosensitive body in the 1st direction, a laser light scanning means for operating the 2nd direction and an optical system moving means. CONSTITUTION:In a constitution consisting of a semiconductor laser 8, a rotary polyhedral mirror 10 and the photosensitive body 12, the variation of the turning speed of the photosensitive body 12 in the narrow F direction is detected by a detector 15, the variation of the turning speed in each fixed scanning and the positional shift of the scanning line in the G direction are found out by a synchronization detector 13 and a collimator lens 9 is moved in the J direction by a moving device 16 in accordance with the shifted value to compensate the positional shift. Therefore, the uneven pitches of the scanning line which may be generated due to the variation of the moving speed of the photosensitive body is compensated only by displacing the lens 9 slightly to execute highly accurate scanning an the relative movement of the laser 8 and the collimator lens 9 can be attained highly accurately with a simple constitution. By using the moving means 16 having an electric distortion 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. 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. 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 6 by the fθ lens 4, and then scans on the photoreceptor S 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 6.

A portion of the laser beam 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 the scanning with respect to the rotational direction of the photoreceptor 6.

However, in the above configuration, the photoreceptor 6
Due to rotational speed fluctuations in the direction of the arrow in the figure, the laser beam scanning line recorded on the photoconductor 6 causes pitch unevenness in the direction of the arrow in the figure, resulting in a problem that the image quality deteriorates. had.

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 a collimator lens that converts the laser light emitted by the semiconductor laser into parallel laser light while moving in a first direction. a member to be irradiated with a laser beam; a speed fluctuation detection means for detecting a speed fluctuation of the movement of the member to be irradiated with the laser beam in the first direction; a laser beam scanning means for scanning the laser beam in a second direction in which the semiconductor laser and the collimating lens are moved in the first direction according to the speed fluctuation detected by the speed fluctuation detection means; and an optical system moving means for moving the optical system relatively in a direction corresponding to the direction corresponding to the laser beam. It performs 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 A synchronization detection device, 14 a semiconductor laser drive device, 15 a photoreceptor rotational speed fluctuation detection device, 1
6 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~
140 The basic operations are the same as the operations 1 to 7 in FIG. 1, so the explanation will be omitted.

The photoreceptor rotational speed fluctuation detection device 15 detects rotational speed fluctuations of the photoreceptor 12 in the direction of arrow F in the figure.

Using the synchronization signal output by the synchronization detection device 13 from the detected rotational speed fluctuation, the average rotational speed fluctuation for each -scanning line is determined, and furthermore, the amount of positional deviation of the scanning line in the direction of arrow G in the figure is determined. . The collimating lens moving device 16 is
According to the detected amount of positional deviation, the collimating lens 9 is moved in the direction of arrow J in the figure to correct the positional deviation.

The extent to which the scanning line shift t can be corrected by moving the collimating lens will be explained with reference to FIG. FIG. 3 is a front view of a half-11IB 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 a This is the 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 laser beam after passing through the collimating lens 18 and the optical axis 21.
1, b is the amount of deviation between the imaging point and the optical axis 21, f,
f2 is collimating lens 18 and fθ lens 1, respectively.
9, the arrows in the figure indicate directions corresponding to arrows G and J in FIG. From FIG. 3, θ can be determined by the following formula.

Go to θ=8 fI...Song...(1) fθ
From the characteristics of the lens, b: f2θ...
(2) (1) P From formula (2), the amount of deviation of the scanning line is usually 5525 μm.
(4), and as an optical system, r, = 1otnt... river... (
) f2 = 250 birds...Mountain (
6) Designed to a degree.

Substituting equations (4) to (6) into equation (3), 461 μm
. . . Mountain (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.

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 of the present invention includes 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, and a laser beam irradiated member that is irradiated with the laser beam while moving; a speed fluctuation detection means for detecting a speed fluctuation of the movement of the laser beam irradiated member in the first direction; a laser beam scanning means for scanning the laser beam in a second direction that is not parallel to the first direction; and a laser beam scanning means for scanning the laser beam in a second direction that is not parallel to the first direction; and an optical system moving means for moving the collimating lens relatively in a direction corresponding to the first direction, whereby the movement of the member to be irradiated with the laser beam is caused by fluctuations in the moving speed of the laser beam irradiated member. It is possible to correct the pitch unevenness of the laser beam scanning line that occurs, and to achieve the unique effect of being able to perform highly accurate scanning.

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・°°・・・Half-four-body laser, 9,18・River...
Collimating lens, 10...Rotating polygon mirror, 15...Photoconductor rotational speed fluctuation detection device, 16...Collimating 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 laser light emitted by the semiconductor laser into parallel laser light; and a member to be irradiated with laser light that is irradiated with the laser light while moving in a first direction; speed fluctuation detection means for detecting speed fluctuations in the movement of the member to be irradiated with the laser beam in the first direction; The semiconductor laser and the collimating lens are relatively moved in a direction corresponding to the first direction according to the speed fluctuation detected by the laser beam scanning means for scanning light and the speed fluctuation detection means. 1. A semiconductor laser beam scanning device characterized by comprising an optical system moving means. (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.