JPS5922992B2 - information reading device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information reading device that reads information on an information carrier by scanning an inertial carrier such as a barcode with a light beam and detecting reflected light from the information carrier. .

Recently, barcode labels such as those shown in Figure 1 are attached to goods such as products, and when the goods are moved due to sale, etc., they are read by a reading device, and based on this data, prices can be aggregated and transaction slips can be created. At the same time, information has come to be sent to a central processing unit and processed as data for inventory management and other purposes.

Conventionally, the reading device for reading this 'ゞ-code is a second
It was configured as shown in the figure.

That is, a hologram 2 having a spatial frequency gradient, which is a deflection piece embedded around the disk 1, is irradiated with laser light 3a from a laser oscillator 3 made into a spherical shape by a lens 4.

When the disk 1 is rotated in this state, a scanning line T as shown in FIG. 3 is drawn through a transparent reading window 6 provided in the housing 5.

The scanning principle is detailed in Japanese Patent Application No. 50-70378 (Japanese Unexamined Patent Publication No. 51-146244), so the explanation will be omitted here. 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. Then, reflected light is generated from the barcode label 9, and this reflected light is detected by the photomultiplier 11 via the filter 10. The electrical signal from this photomultiplier 11 is input to a processing device. A filter 10 is placed in front of the photomultiplier 11 to detect only the reflected light from the barcode label 9. However, since the reading device is usually used in a bright place, 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, the disturbance light passes through the filter 10 and becomes a photomultiplier along with the reflected light. 11. There is no problem if the level of disturbance light incident on the photomultiplier 11 is low, but if it is high, it becomes difficult to distinguish it from the reflected light from the barcode label, and the photomultiplier becomes saturated, making it impossible to read accurate information. .
The purpose of the present invention is to eliminate such drawbacks.The purpose of the present invention is to irradiate a deflection piece provided on a rotating disk with a light beam to draw a scanning line on the reading window, and to perform reading using the scanning line. An information reading device that scans an information carrier on a window, detects reflected light from the information carrier with a photoelectric converter, and converts it into an electrical signal to read the terminal information on the information carrier, The photoelectric converter is the hologram,
Alternatively, this can be achieved by an information reading device characterized in that the reflected light from the information carrier is detected after passing through a condensing hologram having a focal point at the same position as the hologram. Hereinafter, the present invention will be explained in detail based on examples.

FIG. 4 is a plan view showing the principle of the invention.

First, as shown in FIG. 4, when the hologram 2 is irradiated with a laser beam 3a, the laser beam 3a' passing through the hologram 2 is converged onto a point Y on the reading window 6. When the barcode label 9 is located on this point Y1, the light 9a reflected from the barcode label 9 converges on the point X through the same path as the laser beams 3a and 3a'. This is because the point X and the point Y1 are in an imaging relationship. At this time, disturbance light (indicated by a dotted line) enters through the reading window 6 from the part where the barcode label 9 is not present.
Therefore, the disturbance light passing through the hologram 2 converges at a point X' that is distant from the point X.

Furthermore, when the hologram 2 rotates and moves in the direction of arrow A as shown in FIG. 5, the laser beam 3a' passing through the hologram 2
converges on point Y2 of reading window 6. If the barcode label 9 is located on this point Y2, the reflected light from the barcode label 9 will converge on the point X in the same way as described above. Here, the disturbance light (indicated by the dotted line) enters from the part where the barcode label 9 is not present. Since there is no relationship between this incident part and point X, the disturbance light that passed through hologram 2
The image is formed on point X' in the figure, and on point X/7 in FIG. The present inventors invented a configuration as shown in FIG. 6 based on the above phenomenon.

Note that FIG. 6 is a side view. As described above, the reflected light 9a from the barcode label 9 always converges on a specific position X.

Therefore, as shown in FIG. 6, when the reflecting mirror 12 is arranged opposite to the lower part of the hologram 2, the reflected light 9a from the barcode label 9 to the reflecting mirror 12 (indicated by a solid thin line)
Since the incident angle of is constant, when reflected by the reflecting mirror 12, it converges to one point. However, since the disturbance light 9b (indicated by a thin dotted line) converges at different positions, when reflected by the reflecting mirror 12, it does not converge at one point. Therefore, the shutter 1 is placed at a position where the reflected light 9a from the barcode label 9 converges.
If the pinhole 13a of 3 is positioned, the photomaru 1
1 can detect only the reflected light 9a from the barcode label 9. Here, the reflected light may be detected near the point X, but this is not preferable because the reflected light from the surface 2a of the hologram 2 and the laser beam from the laser oscillator mix with the reflected light from the bicode label. For this purpose, a reflecting mirror is used to block the reflected light from the hologram, and the disturbance light 9b and the reflected light 9a are separated in a place not affected by the laser beam from the laser oscillator. Another embodiment of the invention is shown in FIG. In the case of FIG. 7, a scanning hologram 14 and a condensing hologram 15 are arranged separately on the disk 1.

In the figure, 14a is the optical axis of the hologram 14, and 15a is the optical axis of the hologram 15. The scanning hologram 14 and the condensing hologram 15 have the same focal length. Since the holograms 14 and 15 are arranged apart from each other as shown in the figure, the imaging position of the hologram 15 is naturally shifted from the point X. Therefore, in this case, there is no need for a reflecting mirror, making purchasing easier. Here, we will find the placement position of the photomultiplier 11 and prove that light is always focused at this position. Letting the distance from point X to point X5 be X, x = (m-m●+s (
1).

The value of (m−m/) is expressed as follows.

The magnification m/n of the hologram 14 is m/n, where f is the focal length and h is the distance from the hologram 14 to the imaging position.
n=f/b−f (2).

Also, the magnification m'/n-s of the hologram 15 is m/n-s-
f/b−f (3).

From equations (2) and (3), m/n=m'/n-S m(n-s): m'n ′ Mn-Ms-Mn ′ Mn-Mn2msn (m-m′)=Ms m−m′::Ms/n (4).

Substituting equation (4) into equation (1), we get x::Ms/n+s:s(m/n+1) becomes.

Here, m/n is constant and s is also constant.

Therefore, x remains constant.

Another embodiment of the invention is shown in FIG.

FIG. 8 is a side view.

In FIG. 8, a reflecting/absorbing pipe 17 is provided and a reflecting mirror 18 is provided with a hole 18a through which the laser beam 3a passes. Here, the reflected light 9a from the barcode is the laser beam 3
It spreads around a' and returns to point X. Therefore, with this configuration, a larger amount of the reflected light 9a can be collected than in the previous embodiment, so that the intensity of the light incident on the photomultiplier 11 can be increased.

Moreover, since the reflected light from the hologram 16 is cut off, the S/N ratio is improved. As described above, according to the present invention,
Since the reflected light from the mark code label is detected via the hologram, it is possible to prevent the SN ratio from decreasing due to ambient light.

[Brief explanation of drawings]

Fig. 1 shows a '\゜-code label, Fig. 2 shows a conventional reading device, Fig. 3 shows an example of a scanning pattern, and Figs. 4 and 5 show the principle of the present invention. FIG. 6 shows,
FIG. 7 and FIG. 8 are diagrams showing an embodiment of the present invention. In the figure, 1 is a disk, 2 and 16 are holograms, 3 is a laser oscillator, 4 is a lens, 5 is a housing, 6 is a reading window, 8 is an article, 9 is a barcode, 10 is a filter, 11 is a photomultiply, 12 , 18 is a reflecting mirror, 13 is a shutter, 14 is a scanning hologram, 15 is a condensing hologram, and 17 is a reflection/absorption pipe.

Claims (1)

[Claims] 1. A hologram provided on a rotating disk is irradiated with a light beam to draw a scanning line on a reading window, and an information carrier on the reading window is scanned by the scanning line to detect the information from the information carrier. By detecting reflected light with a photoelectric converter and converting it into an electrical signal,
In an information reading device configured to read information on the information carrier, the photoelectric converter converts reflected light from the information carrier after passing through the hologram or a condensing hologram having a focal point at the same position as the hologram. An information reading device characterized by detecting information. 2. The information reading device according to claim 1, wherein the reflected light is detected by changing the direction of the reflected light using a reflecting member. 3. The information reading device according to claim 1, wherein the hologram and the condensing hologram are arranged separately on the disk, and reflected light is detected through these holograms. . 4 A hole through which the light beam passes is provided in the reflecting member, and a reflection/absorption pipe is provided, and the hologram is irradiated with a light beam through the hole and the reflection/absorption pipe to draw a scanning line, and the reflected light from the information carrier is 2. The information reading device according to claim 1, wherein the information reading device detects the information by changing the direction using the reflecting member.