JPH0145108B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a reading device for reading a barcode printed on a medium used in a POS (Point of Sales) system, and particularly relates to the structure of an optical part.

(b) Background of the Technology In recent years, with the spread of computer network systems, electronic registers and stationary reading devices have been used as POS terminals in department stores, supermarkets, etc. These terminals are installed at payment counters, are operated by operators such as store clerks, and are used to read barcodes printed on product labels and the like using reading devices. The barcode displays the product number, product name, and product price. When the barcode is read, the prices are sequentially displayed on the display of the electronic register, and finally, the total price is displayed according to the push button instruction. In addition to the register function, this terminal also functions as a data input device for an information management system that comprehensively performs product management such as sales aggregation, inventory management, and purchase management by sending online sales information for each product to a computer sensor. It is playing a leading role.

(c) Prior Art and Problems A stationary reader used in a POS system will be described below with reference to FIGS. 1 to 3 as an example. FIG. 1 is a perspective view illustrating the usage state of an optical reading device to which the present invention is applied, FIG. 2 is a side sectional view illustrating the outline of the structure of the device, and FIG. It is a side view explaining a state.

As shown in Figure 1, a checkout operator 1 at a supermarket picks up products 2 with barcodes 3 at the counter from one basket to another without stopping.
Move in the direction of arrow V. In this case, the product needs to pass over the transparent window 5 of the reading device 4 within a predetermined dimension. Then, the light (arrow R) emitted from the reading device 4 through the transparent window 5 scans the barcode 3 attached to the product 2, and the reading device 4 reads the reflected light.

FIG. 2 shows an outline of the structure of the reading device. A laser beam emitted from a laser tube 6 is reflected by a mirror 7 as shown by a dashed line and enters a hologram disk 9 which is rotated at high speed by a motor 8. Then, the light is polarized by the diffraction phenomenon of the hologram disk, enters the mirror 10, and is emitted from the reading device 4 through the transparent window 5 upon reflection. At this time, the emitted beam is swung in a plurality of directions due to the rotation of the hologram disk 9.

Because of the above configuration, the precision of the optical system must be extremely high. Therefore, high-precision jigs are used to assemble the optical system, and a large number of man-hours are required to assemble the optical system. Here, as shown in FIG. 3, the laser beam arrow R incident on the hologram disk is diffracted by the hologram disk 9 as shown by the one-dot chain line, and is reflected by the mirror 1.
1 and is emitted as shown by arrow a. This arrow a is called primary light and accounts for 60 to 70% of the amount of incident light (arrow R) of the laser light.

Then, reading is performed using this primary light. However, in addition to the primary light, light corresponding to approximately 3% of the light amount of the incident laser beam arrow R is emitted through the hologram disk 9 as indicated by arrow 0 indicated by a two-dot chain line. This is called 0th order light. In addition, it separates into countless light beams, such as -1st order light with a weak amount as indicated by the dotted arrow a', secondary light (arrow b), and -2nd order light (arrow b').

Therefore, the light other than the effective primary light (arrow a) is unnecessary light, and the inside of the casing 11 of the reading device 4 is made black to prevent troubles caused by diffuse reflection of these unnecessary lights.

(d) Object of the Invention The object of the present invention is to solve the above-mentioned drawbacks, and to provide an optical reading device in which the assembly and adjustment of the optical system is easy and the blackening of the device casing can be omitted.

(e) Structure of the Invention In order to achieve the above object, the present invention uses a hologram disk to irradiate a code or image outside the device with a laser beam emitted from a light source inside the device, and the reflected light is emitted from a hologram disk. is a reading device in which a blackbody region is provided at a predetermined portion where a laser beam incident on a hologram disk in the device passes straight through the hologram disk.

(f) Embodiment of the Invention An embodiment of the present invention will be described below with reference to FIG. FIG. 4 is a side view illustrating a state in which a black area is provided according to the present invention.

In the figure, 10' is a mirror and 12 is a target. Items with the same reference numerals throughout the figures are the same. In the present invention, it is noted that a part of the laser beam (arrow R) that is perpendicularly incident on the hologram disk 9 passes straight through the hologram disk 9 as zero-order light.
The objective is to use secondary light to relatively easily assemble and adjust optical systems, which has been extremely difficult in the past.

That is, the most important thing in this optical reading device 4 is to emit the laser beam from the transparent window 5 in an accurate direction. For this purpose, it is an absolute condition that the laser beam (arrow R) be perpendicularly incident on a predetermined position of the hologram disk 9. Since there is no way to detect this in the conventional technology, the reflected light from the mirror 10' (arrow a)
The direction of laser beam emission from the laser tube 6, the position of the mirror, the angle of inclination, etc. are adjusted using a jig.

However, since a part of the vertically incident laser light, called 0th order light, has the property of penetrating the hologram disk 9 and traveling straight, the target 12 that receives this 0th order light
is set at a predetermined portion of the casing 11 that can be limited in design. Then, the optical system can be adjusted so that the zero-order light coincides with the target 12 visually, without using a high-precision jig or the like.

The target 12 may be, for example, a black circle with a diameter of 5 to 6 mm, and any material that produces a black area in the target 12 may be used, such as pasting a black sticker, painting black, or using a black material such as rubber. anything is fine.
The reason why the target 12 is made black is because the amount of light of the 0th order light is the largest, other than the 1st order light that is actually used for reading.
This is because the other spectral light amounts are too weak to cause any problems, and if only the reflection of the zero-order light is prevented by providing a black area, no trouble will occur.

Therefore, there is no need to blacken the inside of the housing 11 as in the prior art.

(g) Effects of the Invention As explained above, by providing a black target at a predetermined position where the zero-order light incident on the hologram disk reaches as in the present invention, assembly and adjustment of the optical system is facilitated, and the optical reading device The black treatment inside the housing is no longer necessary.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the usage state of an optical reading device to which the present invention is applied, FIG. 2 is a side sectional view illustrating the outline of the structure of the device, and FIG. FIG. 4 is a side view illustrating a state in which a black area is provided according to the present invention. In the figure, 2 is the product, 3 is the barcode, 4 is the reader, 5 is the transparent window, 6 is the laser tube, 7, 10, 1
0' is Mira, 9 is a hologram disk, 11 is a housing, and 12 is a target.

Claims (1)

[Claims] 1 An optical reading device that uses a hologram disk to irradiate a code or image outside the device with a laser beam emitted from a light source inside the device, and reads the reflected light. An optical reading device characterized in that a blackbody region is provided at a predetermined portion where light passes straight through the hologram disk.