JPH0453402B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] Conventional hologram scanners require a space of about 100 mm between the hologram and the scanning pattern forming surface, which impedes the ability to make the device thinner. Therefore, the hologram scanner is made thinner by allowing scanning light to enter the hologram lens from multiple directions.

[Industrial application field]

The present invention relates to a barcode reading device using a laser beam, and more particularly to a hologram scanner that allows the device to be made thinner.

BACKGROUND ART Hologram scanners that use a hologram in a scanning section are becoming widely used as laser scanners that scan a laser beam in accordance with a desired pattern. A hologram scanner is an optical scanning device that is configured so that only a hologram performs the two functions of a rotating polyhedron and a scanning lens in conventional optical scanning devices. By using a scanner, it has become possible to form complex scanning patterns with a simple optical system, and it has become possible to realize barcode reading devices with a deep reading depth. In many cases, barcodes are read while the barcode scanner is installed on a table and the product held in hand is moved, and there is a demand for a laser scanner used in the barcode reader to be even thinner.

[Conventional technology]

FIG. 3 is a schematic diagram showing a conventional hologram scanner, and FIG. 4 is a perspective view showing a conventional fixed hologram.

In FIG. 3, the conventional hologram scanner consists of a laser beam scanning mechanism 10 consisting of a motor 11 and a hologram disk 12 having a plurality of holograms, a mirror 13, a fixed hologram 2, a window cover 15, etc. The scanning light 16 deflected by the mirror 12 is incident on the fixed hologram 2 via the mirror 13. The scanning light 16 incident on the fixed hologram 2 is further deflected and focused on the barcode 17.

Further, the reflected light from the barcode 17, that is, the signal scattered light 18, follows the optical path of the scanning light 1, as shown by the broken line.
6 is propagated in the opposite direction to hologram disk 1.
2, the light is focused by the hologram disk 12 onto a photodetector (not shown), and a barcode 17 is detected.
is read. The signal scattered light 18 enters the fixed hologram 2 in a diverging manner, but since the fixed hologram 2 is close to the barcode 17, it does not spread significantly. Furthermore, since the light is converted into a plane wave by the fixed hologram 2 and is incident on the hologram disk 12, there is an advantage that the light condensing section of the hologram disk 12 can be made smaller.

In such a hologram scanner, the light that scans the surface of the barcode 17 is called a scanning line, and in order to correctly scan the surface regardless of the direction of the barcode 17, the scanning light 16 that has entered the fixed hologram 2 is directed in multiple directions. The beam is deflected to form a plurality of scanning lines. That is, as shown in FIG.
consists of a substrate 21 and hologram diffraction gratings 22, 23, 24 corresponding to the scanning lines, and a plurality of scanning lines 220, 2 are arranged in a space away from the fixed hologram 2.
A scan pattern including 30,240 is formed.

[Problem that the invention seeks to solve]

FIG. 5 is a diagram showing problems in the conventional hologram scanner.

If the reading window formed in the window cover is close to the fixed hologram as shown in FIG. It may not be possible to read the image depending on the position where it passes. For example, a barcode 17 passing through the position indicated by is readable, but a barcode 17 passing through a position indicated by or becomes unreadable. Therefore, it is necessary to provide a reading window at the position where the scanning lines 220, 230, and 240 intersect, as shown in FIG. 5b. In conventional hologram scanners, these scanning lines 220, 230, 2
The distance h from the position where the holograms 40 intersect to the fixed hologram 2 must be at least about 100 mm, which poses a problem in that it impedes efforts to make the hologram scanner thinner.

[Means for solving problems]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. The same objects are represented by the same symbols throughout the figures.

The above problem arises because a scanning pattern is formed using a plurality of hologram diffraction gratings, and the scanning light 41 is incident on one hollow window 3 equipped with a hologram lens 31 and the scanning light 41 is incident on the hologram lens 31 from a plurality of directions. This problem is solved by the hologram scanner of the present invention, which has a laser beam scanning mechanism 4 that focuses the scanning beam 41 using the hologram lens 31 and deflects it in a plurality of directions.

[Effect]

Unlike conventional hologram scanners that form a continuous scanning pattern from independently formed hologram diffraction gratings, this hologram uses a hollow window that integrates a fixed hologram with a hologram lens and a window cover. The scanner does not require the space h to synthesize scan patterns because the scan lines already overlap on the hollow window. Therefore, the distance from the reading area to the hollow window can be significantly shortened, and the hologram scanner can be made thinner.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is an explanatory diagram of the operation of the hologram scanner of the present invention.

In FIG. 2a, when a reference beam 32 and an object beam 33 consisting of a spherical wave or a plane wave are irradiated onto a photosensitive material 35 covered by a mask 34, a hollow window 3 having a hologram lens 31 is formed. When the hologram lens 31 is irradiated with a laser beam 38 from a light source 37 disposed at approximately the same position as the light source 36 of the reference beam 32 as shown in FIG. It focuses on a predetermined position 39 determined by conditions. By scanning the laser beam 38, the focal point 39 moves and draws a scanning line 40.

When light enters a lens from different positions, it is focused at different positions. For example, when a laser beam 380 is emitted from a light source 370 disposed at a different position from the light source 36 of the reference beam 32 as shown in FIG. By focusing on a position 390 and scanning the laser beam 380, the focusing point 390 moves to draw a scanning line 400.

That is, in FIG. 1, the scanning light 41 that is emitted from an arbitrary point 4a of the laser beam scanning mechanism 4 and focused by the hologram lens 31 draws a scanning line 42. Further, the scanning light 41 emitted from another point 4b or 4c of the laser beam scanning mechanism 4 and focused by the hologram lens 31 is scanned by the scanning line 4, respectively.
Draw 3,44.

A hologram scanner using such a hollow window does not require a space h for synthesizing scanning patterns because the scanning lines already overlap on the hollow window. Therefore, the distance from the reading area to the hollow window can be significantly shortened, and the hologram scanner can be made thinner.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a hologram scanner that allows the barcode reading device to be made thinner.

[Brief explanation of drawings]

Figure 1 is a schematic diagram showing one embodiment of the present invention, Figure 2 is a schematic diagram showing an embodiment of the present invention.
3 is a schematic diagram showing a conventional hologram scanner, FIG. 4 is a perspective view showing a conventional fixed hologram, and FIG. 5 is a diagram illustrating a conventional hologram scanner. FIG. 2 is a diagram showing problems. In the figure, 3 is a hollow window, 4 is a laser beam scanning mechanism, and 4 is a hollow window.
a, 4b, 4c are emission points, 31 is a hologram lens, 32 is a reference beam, 33 is an object beam, 34 is a mask, 35 is a photosensitive material, 36, 37, 370 is a light source, 38, 380 is a laser beam, 39, 390 is a focusing point, 40, 400 is a scanning line, 41 is a scanning light, 4
2, 43, and 44 represent scanning lines, respectively.

Claims (1)

[Claims] 1 has one hollow window 3 equipped with a hologram lens 31 and a laser beam scanning mechanism 4 that allows scanning light 41 to be incident on the hologram lens 31 from multiple directions; A hologram scanner that focuses and deflects in multiple directions.