JPS594063B2 - information reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a hologram or the like on a rotating disk to scan an information carrier, and when the reflected light is read through a focusing hologram or the like on the disk, the signal light intensity is increased and the light is focused. The present invention relates to an information reading device with a simplified hologram configuration.

Recently, a bar code label as shown in FIG. 1 has been attached to articles such as commercial products, which is read by an information reading device when the article is moved and processed as data for transactions, inventory management, etc.

A schematic diagram of a conventional information reading device for reading this barcode is shown in FIG.

That is, a laser beam 3 a is irradiated from a laser oscillator 3 via a lens 4 to an optical deflector distributed and embedded around the disk 1 , such as a hologram having a spatial frequency gradient or a Fresnel lens 2 . 5 When the disk 1 is rotated in this state, a scanning line T as shown in FIG. 3 is drawn through the transparent reading window 6 provided in the housing 5.

When a barcode label 9 attached to an article 8 passes over this reading window 6, the barcode label 9 is scanned by a scanning line. 10, reflected light 10 is generated from the barcode label 9, which is received by a photodetector placed at an appropriate position, and any one of the scanning lines shown in FIG. 3 corresponds to the entire barcode. When they intersect, this is read to detect information. However, since the reading device is usually used in a bright place 15, ambient light enters the housing 5 through the reading window 6. This disturbance light includes light of all wavelengths, including light of the same wavelength as the light reflected from the barcode label. Therefore, if the disturbance light is received by the photodetector together with the scanning reflected light, the S/N ratio may deteriorate, or in extreme cases, detection may become impossible. In contrast, the present applicant has filed Japanese Patent Application No. 52-32429 (Japanese Unexamined Patent Publication No. 53-117333),
We have proposed 25 new methods that can eliminate the effects of the above-mentioned disturbance light using an "information reading device."

That is, as shown in FIG. 2, a condensing hologram 11 is separately provided, for example, concentrically, corresponding to the scanning hologram 2 of the rotating disk 1, and its focus is set at approximately the same position as the scanning hologram 2. . Of course, since the optical detector 30 detector 12 is placed near the focal point, it is necessary to take care not to obstruct the main optical path of the laser light source by slightly shifting the position as shown in the figure or by using a reflecting mirror. With this configuration, almost no disturbance light is received by the photodetector 12 provided at this focal position. If there is disturbance light near the 35 scanning point, it will be detected by the photodetector at the focal point along with the reflected light, worsening the S/N ratio, but in reality, the scanning point is on the label code and the main body of the article is behind it. Since the external light is blocked by the light detector 11, the external light does not enter the photodetector 11 described above.
Therefore, reflected light can be detected with a good S/N ratio. FIG. 4 is a partially enlarged view of a rotary disk showing the arrangement of holograms in the proposed example of FIG. 2.

That is, in order to draw scanning lines 13 consisting of rasters of a predetermined pitch in the same direction around the disk 1 on the barcode label 9 with the laser beam 7, as shown in the figure, three scanning lines with equal length in the circumferential direction are drawn. holograms 21, 22, 2
3, are arranged at equal intervals in the circumferential direction. Further, condensing holograms 111, 112, and 113 for concentrically condensing reflected light are provided corresponding to these scanning holograms.
The light is focused through the focusing holograms 111 to 113 onto the photodetector provided at the focal point, but if the scanning holograms 21 to 23 are small, even if the radial dimension is increased, the amount of incident light will not increase much. Therefore, it is difficult to secure a large area. An object of the present invention is to provide an information reading device that can detect by increasing the signal light intensity from a focusing hologram corresponding to each scanning line.

In order to achieve the above object, the information reading device of the present invention irradiates a light beam onto scanning optical deflectors distributed around the rotating disk, draws two scanning lines on the reading window, and uses the scanning lines to draw two scanning lines on the reading window. In an information reading device that scans an information carrier on a reading window and collects reflected light from the information carrier through a condensing optical deflector provided concentrically with a scanning optical polarizer on the disk, A common light condensing optical deflector having the same focal position as one of the three scanning optical deflectors that perform raster scanning at a predetermined pitch is provided, and all the reflected light corresponding to the raster scanning is It is characterized by condensing light. The present invention will be described in detail below with reference to examples.

The principle of the present invention is that a plurality of adjacent holograms are always scanned at a predetermined interval like a raster of a predetermined pitch.
Moreover, it is applied when the reflected light from the scanning point of each hologram is weak, and the shape is a combination of condensing holograms corresponding to multiple scanning holograms, and the same focal position as one of the multiple holograms is used. It is something that you have.

In this case, the signal light intensity is high because the condensing area is large, but on the other hand, a plurality of focal points are generated, and it is necessary to distinguish between them. FIG. 5 is an explanatory diagram showing the configuration of an embodiment of the present invention.

In this figure, the difference from FIG. 4 is the shape of the condensing hologram, in which a common condensing hologram 21 corresponding to scanning holograms 21, 22, and 23 is provided, and this condensing hologram 21 is, for example, It has the same focal point P2 as the scanning hologram 22. Therefore, this condensing hologram 21
When the reflected light from the scanning lines of the scanning holograms 2, 22, and 23 is collected, P, , P shifted from the focal point P2
3, the focus is separated. Therefore, it is necessary to take this point into consideration when making a discrimination, but since the raster is a raster with a predetermined pitch, this discrimination is easy. As explained above, according to the present invention, by providing a common large condensing hologram that corresponds to a plurality of scanning holograms and has the same focal position as one of the holograms, a large condensing area can be obtained. This is particularly effective when the reflected light corresponding to the scanning hologram of each raster is weak, since it is possible to increase the signal light intensity when this light is focused.

It goes without saying that the configuration of the condensing hologram can also be simplified.

[Brief explanation of drawings]

1 to 4 are explanatory diagrams of conventional proposals, and FIG. 5 is an explanatory diagram showing the configuration of an embodiment of the present invention. In the figures, 1 is a disk, 21 to 22 are scanning holograms, and 7 Laser light, 1
0 indicates reflected light, 13 indicates a scanning line, and 21 indicates a condensing hologram.

Claims (1)

[Claims] 1. A light beam is irradiated onto scanning optical deflectors distributed around the rotating disk, a scanning line is drawn on the reading window, the information carrier on the reading window is scanned by the scanning line, and the information carrier is extracted from the information carrier. In the information reading device, a plurality of scanning optical deflectors for performing raster scanning at a predetermined pitch are used. An information reading device characterized in that a common optical deflector for focusing light having the same focal position as one of the objects is provided with respect to the body, and all reflected light corresponding to the raster scanning is focused.