JP2743561B2 - Mirror for laser beam scanner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mirror mounted on a rotating shaft of a motor for reflecting a laser beam output from a laser oscillator and scanning the object surface with the laser beam. The present invention relates to a laser beam scanner mirror provided on a surface.

[Prior art] For a printer, various measuring devices, a barcode reader, and other devices for scanning and detecting a laser beam, a laser beam scanner motor generally equipped with a polygon mirror called a polygon mirror on a rotation axis is used. Have been.

5 and 6 are a plan view and a side view of a conventional example, respectively.

The laser beam output from the laser oscillator a is a motor b
The light is reflected by the outer peripheral surface of the polygon mirror c attached to the rotating shaft of, and is irradiated on the laser irradiation surface d of the object.

Here, the polygon mirror c has, for example, a hexagonal shape in plan view (of course, is not limited to a hexagonal shape) as shown in the figure, and the outer peripheral surface is formed as a mirror surface.

If the rotation axis of the motor b makes one rotation, the laser beams reflected by the respective mirror surfaces on the outer peripheral surface become points A and B on the laser irradiation surface d.
The space is scanned by the number of mirror surfaces on the outer peripheral surface of the polygon mirror c.

[Problems to be solved by the invention]

Irradiation of a laser beam as described above in a laser beam printer or the like requires that the scanning speed between points A and B is always constant.

For this reason, it is necessary to minimize the dimensional processing accuracy of each outer peripheral surface of the polygon mirror c and the jitter value due to rotation unevenness and the like, and the dimensional processing accuracy and the finishing accuracy of the polygon mirror c centered on the laser beam reflecting surface. Good things are required.

The polygon mirror c has a plurality of reflecting surfaces, and in order to finish it with high accuracy, a high-precision and expensive processing machine is required, a high-level processing technique is required, and the work process is complicated. .

For this reason, the price of polygon mirror in the price of laser beam scanner occupies nearly half in some cases,
It is difficult to reduce the cost of the laser beam scanner.

In addition, the laser irradiation surface is a straight line, and the distance from the polygon mirror c increases as the distance from the center to the outside increases,
The scanning distance on the laser irradiation surface d with respect to the rotation angle of the polygon mirror c does not correspond one-to-one.

Therefore, in a laser beam printer or the like, correction is performed using a lens e called an _Fθ lens as shown in FIG.
It corresponds to one to one.

Here, too, there is a problem that the processing accuracy of the _Fθ lens e is required, and the number of parts is increased, which hinders the cost reduction of a laser beam printer or the like.

An object of the present invention is to provide a mirror for a laser beam scanner that can be easily processed and that can arbitrarily set a correspondence of a scanning distance on a laser irradiation surface with respect to a rotation angle in view of the above problems.

[Means for solving the problem]

In order to achieve the above object, the present invention has a substantially cylindrical shape attached to a rotating shaft of a motor, and a mirror surface for reflecting a laser beam output from a laser oscillator and scanning the object surface with the laser beam is provided on an outer peripheral surface. And a mirror for a laser beam scanner, wherein the mirror surface is constituted by one or a plurality of spiral grooves, and a cross section of the spiral groove is a part of an arc, an ellipse, or another curve. It is.

[Action]

The mirror for a laser beam scanner according to the present invention is configured as described above, and is mounted on a rotating shaft of a motor and arranged so that a laser beam output from a laser oscillator irradiates a mirror surface on an outer peripheral surface.

Here, since the mirror surface is formed by one or a plurality of spiral grooves, when the motor is rotated, the mirror surface on the outer peripheral surface of the mirror also rotates, and the irradiation position of the laser beam output from the laser oscillator is changed. Changes the angle of the mirror surface, and the reflected light is scanned on the object surface.

In addition, while the apparatus using a polygon mirror scans a laser beam in a direction orthogonal to the rotation axis of the motor, the present invention scans the laser beam in a direction parallel to the rotation axis of the motor.

〔Example〕

 The details of the present invention will be described based on an illustrated embodiment.

FIG. 1 is a side view for explaining an embodiment of a mirror for a laser beam scanner according to the present invention.

Reference numeral 1 denotes a laser oscillator that outputs a laser beam for scanning the surface of an object.

Reference numeral 2 denotes a motor provided to face the laser oscillator 1, and a mirror 4 is attached to the rotating shaft 3.

The mirror 4 has a substantially cylindrical shape, and the outer peripheral surface forms a mirror surface for reflecting a laser beam from the laser oscillator 1.

The mirror surface of the mirror 4 is formed by one or a plurality of spiral grooves 5 as shown in the figure, and the cross section of the groove 5 is an arc, an ellipse, or a part of another curve.

At least the outer peripheral surface of the mirror 4 is made of aluminum or other metal, other engineering plastics, or the like, and the mirror surface of the outer peripheral surface can be processed by a precision lathe or the like while rotating the whole.

The laser beam output from the laser oscillator 1 is reflected by the mirror surface of the mirror 4 and scans the laser irradiation surface 6 of the object.

The outer peripheral surface of the mirror 4 that reflects the laser beam from the laser oscillator 1
It changes as shown in FIG. 3, FIG. 3, and FIG.

That is, the laser beam output from the laser oscillator 1 is reflected by the mirror 4 at a fixed angle with respect to the rotation axis 3 of the motor 2.
The mirror surface is illuminated.

Here, since the mirror surface of the mirror 4 is formed by the spiral groove 5 whose cross section is a part of an arc, an ellipse, or another curve, the angle between the laser beam incident light and the mirror surface of the mirror 4 is changed by the motor. 2 in a direction parallel to the rotation axis 3.

Since the laser beam is reflected so that the incident light and the reflected light are at the same angle with respect to the normal to the mirror surface of the mirror 4, the reflected light moves in a direction parallel to the rotation axis 3 of the motor 2 and the laser irradiation surface 6. Is scanned in the vertical direction in the figure.

Since the mirror 4 in the illustrated example has one spiral groove 5,
The scanning between the points A and B on the laser irradiation surface 6 is performed once per rotation of the rotating shaft 3 of the motor 2.

Therefore, by providing n grooves 5 of the mirror 4,
This makes it possible to perform n scans per rotation of the rotating shaft 3 of the motor 2.

The cross-sectional shape of the groove 5 can be a part of an arc, a part of an ellipse, or a part of another curve, and the scanning distance of the laser beam with respect to the rotation angle of the mirror 4 is set arbitrarily by this shape. Is what you can do.

From this, by appropriately setting the cross-sectional shape of the groove 5 of the mirror 4, the scanning distance of the laser beam with respect to the rotation angle of the mirror 4 can be made to correspond one-to-one, and when used in a laser beam printer or the like. This eliminates the need for correction using an _Fθ lens or the like, and can reduce the number of parts.

〔The invention's effect〕

The mirror for a laser beam scanner according to the present invention is configured as described above, the sectional shape of the groove of the mirror surface can be made arbitrary, and the relationship between the rotation angle of the mirror and the scanning distance of the laser beam can be set arbitrarily. It is possible.

One or more spiral grooves of the mirror can be provided, and the number of scans per one rotation of the mirror can be arbitrarily selected.

In addition, conventional polygon mirrors use a plane cutting machine for processing.
Although a polishing machine or the like was required, in the present invention, it is possible to perform the work with a precision lathe or the like while rotating the mirror, and it is easy to finish the work, simplify the work process, and reduce the cost. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a side view for explaining a mirror for a laser beam scanner according to the present invention, FIG. 2, FIG. 3, and FIG. 4 are views for explaining reflected light of a laser beam accompanying rotation of the mirror, and FIG. FIG. 6 is a plan view of a conventional example, FIG. 6 is a side view of the conventional example, and FIG. 7 is an explanatory diagram of an _Fθ lens in the conventional example. 1: Laser oscillator, 2: Motor, 3: Rotation axis, 4: Mirror, 5: Groove, 6: Laser irradiation surface.

Claims (1)

(57) [Claims] An outer peripheral surface of a substantially cylindrical shape attached to a rotating shaft of a motor for reflecting a laser beam output from a laser oscillator and scanning the surface of a target object with the laser beam. A mirror for a laser beam scanner, comprising one or a plurality of spiral grooves, wherein a cross section of the spiral groove is a part of an arc, an ellipse, or another curve.