JPH0627398A - Laser beam scanner - Google Patents

Abstract

PURPOSE:To easily adjust beam waist in a vertical and a horizontal vibration directions with simple constitution in a laser beam scanner which emits laser beam for scanning. CONSTITUTION:The scanner consists of a semiconductor laser 11 which emits laser beam, a converging lens 12 which independently controls the beam waist position in the vertical vibration direction and the beam waist position in the horizontal vibration direction and is tilted to the optical axis of the laser beam and placed in the vicinity of the laser beam emitting end of the semiconductor laser 11 and a beam scanning means 20 which continuously and regularly changes the advancing direction of the laser beam passing through the converging lens 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam scanning device for emitting and scanning a laser beam.

Laser beam scanning devices are widely used in bar code readers, laser printers and the like. In order to secure the depth of focus of the laser beam, a beam waist in the vertical vibration direction and a beam waist in the horizontal vibration direction are used. Need to be set independently.

[0003]

2. Description of the Related Art In recent years, a laser light source used in a laser beam scanning device has been replaced with a semiconductor laser from a He-Ne laser device, and miniaturization and cost reduction have been promoted. However, shaping of an emission beam is more difficult with a semiconductor laser. Is.

Conventionally, in shaping a laser beam emitted from a semiconductor laser, a maximum diameter is regulated by using a pinhole aperture, and a beam emitted from the semiconductor laser is received by a collimator lens so that a vertical vibration direction and a horizontal vibration direction can be obtained. A plurality of cylindrical lenses or prisms for arranging the beam waist position of each of the above in a desired position are arranged.

[0005]

However, if a plurality of cylindrical lenses and prisms are provided at the emitting end of the semiconductor laser in addition to the collimator lens, the number of parts becomes large and the apparatus becomes complicated, and the adjustment work of the beam waist is also required. Since it is not simple, there is a drawback that the parts and the assembly and adjustment are considerably expensive.

Therefore, an object of the present invention is to provide a laser beam scanning device which can easily adjust the beam waist in the vertical vibration direction and the horizontal vibration direction with a simple structure.

[0007]

In order to achieve the above object, a laser beam scanning device of the present invention includes a semiconductor laser 11 for emitting a laser beam as shown in FIG. 1 for explaining an embodiment. , Focus the laser beam,
In addition, in order to independently control the beam waist position in the vertical vibration direction and the beam waist position in the horizontal vibration direction, the beam waist position is tilted with respect to the optical axis of the laser beam and is positioned near the laser beam emission end of the semiconductor laser 11. It is characterized in that a converging lens 12 arranged and a beam scanning means 20 for continuously and regularly changing the traveling direction of the laser beam passing through the converging lens 12 are provided.

The converging lens 12 may be disposed so as to be tilted in the vertical vibration direction of the laser beam, and tilt angle control means 18 for changing the tilt angle of the converging lens 12 may be provided.

The converging lens 12 is formed by a spherical or aspherical lens, and the converging lens 1 is formed.
A pinhole aperture 13 for restricting the outer diameter of the laser beam that has passed through 2 is arranged and the converging lens 12
The laser beam may be shaped by the pinhole aperture 13 and the pinhole aperture 13.

[0010]

As shown in FIG. 5, in the semiconductor laser 91, the light emitting point is different between the light wave in the vertical vibration direction and the light wave in the horizontal vibration direction. Generally, the light emitting point 92 in the vertical vibration direction is the horizontal vibration direction. From the light emitting point 93 of 5 μm to 10 μm
There is an astigmatic difference that is located only outside.

Therefore, as shown in FIG. 6, when the laser beam emitted from the semiconductor laser 91 is converged by one convex lens 94, the beam waist 95 in the vertical vibration direction is the beam waist in the horizontal vibration direction. It is formed farther than 96.

However, depending on the purpose of use, it may be necessary to make the position of the beam waist 95 in the vertical vibration direction closer to the position of the beam waist 96 in the horizontal vibration direction, or to set both beam waists 95, 96 at the same position. .

Therefore, as shown in FIG. 7, the convex lens 9
When 4 is tilted with respect to the optical axis in the plane of the vertical vibration direction, only the position of the beam waist 95 in the vertical vibration direction approaches the convex lens 94 side.

This phenomenon is due to the coma aberration generated by the convex lens 94 having an angle with respect to the optical axis. The beam waist position in the inclined direction becomes closer to the convex lens 94 side as the convex lens 94 is inclined to a greater extent. .

The present invention utilizes this development,
By arranging the converging lens 12 so as to be inclined with respect to the optical axis of the laser beam, the beam waist in the inclined direction approaches the side of the converging lens 12. Therefore, by changing the inclination direction and the inclination angle of the converging lens 12, The beam waist in any direction can be set at any position.

As a result, the laser beam whose traveling direction is continuously and regularly changed by the beam scanning means 20 can obtain the most desirable depth of focus for the object to be scanned. If the tilt angle control means 18 is provided, the tilt angle of the converging lens 12 can be freely changed.

Further, the pinhole aperture 13 for controlling the outer diameter of the laser beam passing through the converging lens 12 is provided, and the beam shaping of the laser beam can be performed only by the converging lens 12 and the pinhole aperture 13.

[0018]

Embodiments will be described with reference to the drawings. FIG. 2 shows an embodiment in which the present invention is applied to a bar code scanner.

In the figure, reference numeral 10 denotes a semiconductor laser module containing a semiconductor laser 11 for emitting a laser beam and a converging lens 12 for converging the laser beam emitted from the semiconductor laser 11.

A spherical or aspherical convex lens is used as the converging lens 12, and is arranged in the vicinity of the laser beam emitting end of the semiconductor laser 11 so as to face the laser beam emitting end.
A pinhole aperture 13 is formed in the laser beam emitting portion of the semiconductor laser module 10, and the outer diameter of the laser beam is regulated here.

The laser beam emitted from the semiconductor laser module 10 is reflected by the plane mirror 19 and enters the scanning optical system 20. Then, the light is reflected by a small plane mirror portion 22 formed in the center of the concave mirror 21 and goes toward the reflecting surface of the polygon mirror 23.

The polygon mirror 23 is rotationally driven at a constant speed. Therefore, the laser beam is reflected by the reflecting surface of the polygon mirror 23 while continuously changing its direction. Then, one of the three plane mirrors forming the three-sided mirror 24 is reflected toward the bottom surface mirror 25.

On the surface of the scanning optical system 20, a hologram window 26 of a refractive index distribution type in which a hologram material having a refractive index different depending on a place is formed on a transparent plate or a relief type in which a diffraction grating by unevenness is formed on the transparent plate. A hologram window is arranged, and the laser beam reflected by the bottom surface mirror 25 passes through the hologram window 26 to be refracted and converged.

Since the polygon mirror 23 is rotated, the laser beam is scanned in one direction at high speed with the vertical oscillation direction of the light wave as the scanning direction, and the barcode 1
It hits 00 and is reflected.

FIG. 3 is a side view of the scanning optical system 20,
The laser beam reflected by the barcode 100 outside the hologram window 26 passes through the hologram window 26 and is sequentially reflected by the bottom mirror 25, the three-sided mirror 24, and the polygon mirror 23, and then the concave mirror 2.
After being reflected by 1 and converged, and reflected by a small plane mirror 27, it is incident on a photodetector 28 arranged at the converging point of the laser beam by the concave mirror 21 and converted into an electric signal.

In this way, in the scanning optical system 20, the laser beam is scanned by the rotation of the polygon mirror 23, and the bar code 100 can be read by the output signal from the photodetector 28.

FIG. 1 shows the internal structure of the semiconductor module 10. The converging lens 12 is fixed to the lens holder 14. The lens holder 14 can be freely tilted in the vertical vibration direction of the laser beam about an axis 15 arranged in the horizontal vibration direction of the laser beam emitted from the semiconductor laser 11.

The gear 16 fixed to the shaft 15 is driven by a motor 18 via a reduction gear 17. Reference numeral 18a is a motor driver circuit, and 11a is a semiconductor laser driver circuit.

With such a configuration, the converging lens 12 is arranged so as to be tilted in the vertical oscillation direction of the laser beam,
Similar to that shown in FIG. 7, the beam waist in the vertical vibration direction is closer to the converging lens 12 than the beam waist in the horizontal vibration direction.

At the time of assembly or as needed, the tilt angle of the converging lens 12 can be changed by driving the motor 18 to adjust the beam waist position in the vertical vibration direction independently of the beam waist in the horizontal vibration direction. it can.

As a result, the beam shape of the scanning beam can be adjusted to a circular beam or an elliptical beam at an arbitrary position having a spatial spread to obtain the most desirable depth of focus for the barcode 100 to be read. it can.

FIG. 4 shows a second embodiment of the present invention, and shows an example in which the present invention is applied to a scanning device of a laser printer in which a hologram disk 31 is rotated to scan a laser beam. , 32 are photosensitive drums.

In this case, the beam waists in the vertical vibration direction and the horizontal vibration direction are at the same position, and the photosensitive drum 3
2 The angle of the converging lens 12 is fixed to an angle such that a circular beam is irradiated on the surface.

The present invention is not limited to the above-described embodiment. For example, the converging lens 12 can change the angle not only in the vertical vibration direction of the laser beam but also in the horizontal vibration direction. You may

[0035]

According to the laser beam scanning device of the present invention, the beam waist position in the vertical vibration direction and the beam waist position in the horizontal vibration direction can be set to each other simply by arranging the converging lens at an angle with respect to the optical axis of the laser beam. It can be set independently and arbitrarily, and as a result, the most desirable depth of focus and beam shape can be easily obtained.

Since the laser beam can be shaped only by the converging lens and the pinhole aperture,
The configuration of the device can be made very simple, and the component cost and the assembly adjustment cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a semiconductor laser module according to a first embodiment.

FIG. 2 is a perspective view of the laser beam scanning device according to the first embodiment.

FIG. 3 is a side view of the scanning optical system according to the first embodiment.

FIG. 4 is a perspective view of a laser beam scanning device according to a second embodiment.

FIG. 5 is a characteristic explanatory diagram of a semiconductor laser.

FIG. 6 is a characteristic explanatory view of a semiconductor laser.

FIG. 7 is a characteristic explanatory diagram of a semiconductor laser.

[Explanation of symbols]

 11 semiconductor laser 12 converging lens 13 pinhole aperture 20 scanning optical system (beam scanning means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location H04N 1/04 104 A 7251-5C (72) Inventor Yuichiro Takashima 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Address within Fujitsu Limited

Claims (4)

[Claims] 1. A semiconductor laser (1) for emitting a laser beam.
1) and, in order to converge the laser beam and independently control the beam waist position in the vertical vibration direction and the beam waist position in the horizontal vibration direction, the laser beam is tilted with respect to the optical axis of the laser beam, and Converging lens (12) arranged near the laser beam emitting end of the semiconductor laser (11), and beam scanning for continuously and regularly changing the traveling direction of the laser beam passing through the converging lens (12). A laser beam scanning device comprising means (20). 2. The laser beam scanning device according to claim 1, wherein the converging lens (12) is arranged so as to be inclined in a vertical oscillation direction of the laser beam. 3. The laser beam scanning device according to claim 1, further comprising tilt angle control means (18) for changing the tilt angle of the converging lens (12). 4. The converging lens (12) is formed by a spherical or aspherical lens, and the converging lens (1) is formed.
A pinhole aperture (13) for restricting the outer diameter of the laser beam that has passed through 2) is arranged, and the converging lens (12) and the pinhole aperture (13) perform beam shaping of the laser beam. The laser beam scanning device according to claim 1, 2 or 3, wherein