JPH071350B2 - Laser optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A laser light scanning device comprising a light scanning unit such as a hologram disk and a fixed hologram for forming a scanning pattern, the reference light side and the object light side of the fixed hologram. By reproducing from both sides of the scanning pattern to form a scanning pattern, the scanning line is converted from horizontal scanning to vertical scanning,
Enables thinner devices.

[Industrial application field]

The present invention relates to a laser beam scanning device such as a bar code reading device for reading a bar code of a product.

[Conventional technology]

FIG. 6 shows the structure of a conventional laser beam scanning device using a hologram. This is composed of a scanning laser light generator 1 and a light scanning unit 2. The scanning laser light generator 1 includes a laser light source 3, a beam expander 4, mirrors 5 and 6, a perforated lens 7 having a hole 7a, and a mirror. 8, a motor 9, a hologram disc 10, and a photodetector 11 are provided, and the optical scanning unit 2 is provided.
Is composed of a plurality of mirrors 12 to 16. Further, a reading window 19 provided with a fixed hologram 18 is provided on the upper surface of a housing 17 that houses these. Then, the laser light generated by the laser light source 3 is made into laser light having a predetermined diameter by the beam expander 4, reflected by the mirrors 5 and 6 and passing through the hole 7a of the lens 7, and further reflected by the mirror 8 so that the motor It is incident on a hologram disk 10 which is rotated by 9, is redirected here, is reflected by an appropriate one of the mirrors 12 to 16 and is emitted as a scanning beam A from a reading window 19 to irradiate a bar code 20a of a product 20. To do. Barcode 2
0a receives the scanning beam A and reflects it as scattered light B. The scattered light B is collimated by the fixed hologram 18 and reaches the hologram disc 10 through the original optical path, where it is diffracted, reflected by the mirror 8, condensed by the lens 7, and detected by the photodetector 11. It has become.

[Problems to be solved by the invention]

In the above-mentioned conventional laser light scanning device, the mirrors 15 and 16 just before being emitted from the device need to have a size corresponding to the required scanning line length, which is an obstacle to making the device thinner.

The present invention was created in view of the above circumstances, and an object thereof is to provide a laser light scanning device that can be made thin.

[Means for solving problems]

Therefore, in the present invention, in the laser beam scanning device including at least the optical scanning unit 2 including the hologram disk and the fixed hologram 24 provided in the reading window, the fixed hologram 24 includes the reference light side and the fixed light side. It is characterized in that scanning light is made incident from both the object light side to form a scanning pattern.

[Action]

FIG. 1 is a diagram for explaining the principle of the present invention. This figure shows a method for producing a fixed hologram provided in the reading window. As shown in FIG.
It is created by using the reference light 22 of a divergent spherical wave and the object light 23 of a divergent spherical wave having a point light source at a position symmetrical with respect to the YZ plane perpendicular to.

In the hologram 24 thus created, since the created light is incident at an equiangular angle, the interference fringes 25 have a vertical inclination as shown in FIG. 2, so that double-sided reproduction is possible and a plurality of holograms on the hologram can be reproduced. Scanning lines can be formed.

〔Example〕

FIG. 3 is a diagram showing an embodiment of the present invention. In the figure, 2 is an optical scanning unit, 9 is a motor, 10 is a hologram disk, 12 is a mirror, and 19 is a reading window provided with a fixed hologram 18. The scanning laser light generator is similar to that shown in FIG. 1 and is not shown.

As shown in FIG. 3, this embodiment is different from the conventional example shown in FIG. 6 in that the mirrors 13 to 16 are removed and the mirror 12 is removed.
The hologram 24, which is made almost as shown in FIG.
Was used.

In this embodiment having the above-described structure, the two scanning light beams diffracted by the hologram disk as shown in FIGS.
If A and B are made incident on the reference light side and the object light side of the fixed hologram 18, respectively, as shown in FIG.
Horizontal scanning between a and a'-b ', and c- as shown in FIG.
Vertical scanning between d and c'-d 'can be performed simultaneously.

According to the present embodiment, the scanning line in the vertical direction is converted from the horizontal scanning to the vertical scanning by the fixed hologram.
The mirrors 15 and 16 shown in the conventional example in the figure are not required, and the device can be thinned.

Further, in the conventional example, there is a difference in the distance from the scanning point P at both ends e and f of the scanning line as shown in FIG. 7, but in this embodiment, the difference can be almost eliminated as shown in FIG. As a result, scanning can be performed on the image plane and scanning can be performed in a state close to ideal.

〔The invention's effect〕

As described above, according to the present invention, it is possible to reduce the thickness of the laser beam scanning device with an extremely simple structure, which is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a diagram showing a method for reproducing the hologram produced in FIG. 1, FIG. 3 is a diagram showing an embodiment of the present invention, and FIG. Is a diagram showing horizontal scanning line reproduction of a fixed hologram, FIG. 5 is a diagram showing vertical scanning line reproduction of a fixed hologram, FIG. 6 is a diagram showing a configuration of a conventional laser beam scanning device, and FIG. 7 is a conventional laser It is a figure which shows the scanning line of an optical scanning device. In FIGS. 1, 2, 3, and 4, 2 is an optical scanning unit, 9 is a motor, 10 is a hologram disc,
12 is a mirror, 19 is a reading window, 21 is a dry plate, 22 is a reference beam,
23 is an object beam and 24 is a fixed hologram.

Claims (2)

[Claims] 1. An optical scanning unit (2) provided with a hologram disk and the like, and a fixed hologram (2) provided in a reading window.
In the laser beam scanning device including at least 4), the fixed hologram (24) is characterized in that scanning light is incident from both sides of the reference light side and the object light side to form a scanning pattern. And a laser beam scanning device. 2. The fixed hologram (24) according to claim 1, characterized in that the reference light and the object light are created by diverging spherical waves from equidistant point light sources. Laser light scanning device.