JPS6111810Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an optical reading device, and in particular to an optical reading device such as a barcode reading device that scans a light beam and receives scattered light from an object to read information. Regarding.

In an optical reading device such as a barcode reading device, a method for easily condensing scattered light from an object to be scanned must be used as a light beam scanning means. For this reason, in addition to the conventional rotating polygon mirror, hologram scanners have recently been used. Equivalently, a hologram scanner scans a light beam by moving a lens composed of a diffraction grating, so this lens action can also be used to focus scattered light, which has the advantage of simplifying the optical system. . However, since barcode reading devices are required to read labels regardless of their orientation, it is necessary to scan the object to be scanned using intersecting scanning lines. On the other hand, since a hologram scanner can only perform parallel scanning, a method of changing the scanning direction by reflecting the scanning beam with a reflecting mirror is used to construct intersecting scanning lines. In this case, since the hologram that participates in scanning is also used to collect scattered light, depending on the arrangement of the reflecting mirrors, the scattered light may not reach the hologram. Therefore, conventionally, reflecting mirrors are arranged as shown in FIG. FIG. 1 is a perspective view showing a conventional optical reading device, in which a light beam 1 emitted from a light beam generator (not shown) illuminates a hologram disk 9 on which a plurality of holograms 2 to 8 are arranged on the circumference. do. Hologram disk 9 rotates about central axis 10 in the direction of arrow 11, and each hologram 2-8 generates a scanning line. In order to form intersecting scanning lines on the scanning plane 12, for example, the scanning line by the hologram 2 is formed by a scanning line 15 which is scanned by the reflecting mirror 13 on the scanning plane 12 in the direction of the arrow 14.
reflected as. A scanning line from a hologram 3, which is different from the hologram 2, is reflected by a reflecting mirror 16 as a scanning line 18 (the scanning line from the hologram 3 is shown by a broken line) that scans on the scanning surface 12 in the direction of an arrow 17. A scanning line pattern intersecting with the scanning line 15 is formed. In such a conventional optical reading device, as will be explained next, the hologram itself, which is involved in the scanning, focuses the scattered light from the object to be scanned, so there are restrictions on the arrangement of the reflecting mirrors 13 and 16. The scanning line length is not sufficient. FIGS. 2a, 2b, and 2c are diagrams for explaining the convergence of scattered light in a conventional optical reading device. FIG. 2a is a cross-sectional view showing a state in which the upper end of the hologram 2 in FIG. 1 is irradiated with the light beam 1. In FIG. 2a, only the hologram 2 is shown, and the other holograms of the hologram disk 9 are omitted. In FIG. 2a, the scanning beam (diffracted light from the hologram) 19 is located at the scanning point 20
is being scanned. Scattered light from the scanned object at the scanning point 20 exits in various directions, but the hologram 2
The scattered light that has reached the point 23 is focused by the lens action of the hologram 2. The light focused on the point 23 is spatially separated from the light beam 1 by an anti-transparent mirror or a perforated mirror, photoelectrically converted, and information about the scanned object is detected. In this case, in order for the scattered light to reach the hologram 2, the reflecting mirror 22 corresponding to the reflecting mirror 13 in FIG.
It must be possible to reflect scattered light in a range between 9 and 21. Next, hologram disk 9
Considering the case where the hologram 2 is rotated in the direction of the arrow 11 and the hologram 2 is in the position shown in FIG. There is. In this state, in order for the scattered light from the scanning point 25 to reach the hologram 2, the reflecting mirror 27 corresponding to the reflecting mirror 13 in FIG.
is the scanning beam 24 and the scattered light 2 as shown in Figure 2b.
It must be possible to reflect scattered light in the range between 6 and 6. The scanning beam 19 and the scattered light 21 for the case of FIG. 2a are also shown simultaneously in FIG. 2b, as a result of which
It can be seen that the reflecting mirror 27 needs to be spatially arranged to be able to reflect the scanning beam and the scattered light in the range between the scattered light 21 and the scattered light 26. Therefore, the scanning range is limited to between scanning points 20 and 25,
The scanning angle portion in the range indicated by the arrow 28 cannot be used because the reflecting mirrors 13 and 16 overlap. FIG. 2c is a diagram showing the range of scanning lines from holograms 2 and 3. Since the reflectors 13 and 16 must be arranged so that they do not overlap, hologram 2
The scanning line from the hologram 3 can be used for optical reading only in the range between the scanning points 20 and 25, and the scanning line from the hologram 3 can only be used in the range between the scanning points 29 and 30. The portion corresponding to scan angle 31 is not available.

As you can see from the above explanation, the scanning line length of conventional optical reading devices is limited, and in order to obtain long scanning lines, the scanning angle (diffraction angle) must be large, and the scanning beam In addition to the occurrence of aberrations, the spatial frequency of the hologram increases, making it extremely difficult to manufacture. Furthermore, although the above explanation is an example of two crossing lines, obtaining three crossing scanning lines is
Furthermore, the scanning range was limited, making it virtually impossible.

The purpose of this invention is to provide an optical reading device that can perform cross-scanning with a large scanning line length without increasing the diffraction angle of the hologram.

Another object of this invention is to provide an optical reading device capable of triple-cross scanning.

The optical reading device of this invention includes a hologram disk in which a plurality of holograms are arranged on the circumference, means for rotating the hologram disk, a light beam generator installed to irradiate the hologram, and an object to be scanned. means for detecting the light diffracted by the hologram participating in the light scanning on the hologram disk out of the scattered light from the hologram disk; and space division into scanning lines in the scanning direction having substantially the entire length of the scanning lines by the hologram. and a means for reflecting the light.

Next, this invention will be explained in detail with reference to the drawings.

FIG. 3 is a perspective view showing a first embodiment of this invention, in which a light beam 1 emitted from a light beam generator (for example, a laser device) (not shown) forms a plurality of holograms 31 to 36 on the circumference. The hologram disks 9 arranged individually are irradiated. Hologram disk 9 rotates about central axis 10 in the direction of arrow 11, and each hologram 31-36 generates a scanning line. In a conventional optical reading device, one hologram corresponds to one scanning line, but in this embodiment, the scanning line from one hologram is generated by reflecting mirrors 37 and 40 whose normals to the reflecting surfaces intersect with each other. One set (two in this example) that are split and reflected in different directions and intersect.
A feature is that the reflecting mirrors 37 and 40 are arranged so as to constitute a scanning line. i.e. arrow 4
One hologram, for example, 31 scans the scanning angle range shown by 3, and is dividedly reflected by reflecting mirrors 37 and 40 arranged as described next, and scans in the direction shown by arrow 38 with a scanning line 39 and an arrow. A cross-scanning pattern is formed on the scanning surface 12 as scanning lines 42 scanning in the direction indicated by 41. Therefore, a wide scanning angle and a long scanning line can be obtained without increasing the diffraction angle of the hologram. Reflecting mirrors 37 and 40 are plane mirrors in this embodiment. A spherical mirror or an aspherical mirror may be used if only to generate a crossing pattern of scanning lines, but in that case, the beam diameter on the scanning surface,
The scanning speed changes depending on the curvature of the reflective surface, and
The scanning line is curved due to curved surface reflection. Therefore, a plane mirror is the simplest means. Reflector 37 and 4
The arrangement of 0 will be explained. The angle formed by the reflecting surfaces of the reflecting mirrors 37 and 40 corresponds to the scanning line 39 on the scanning plane 12.
and 42 intersect at approximately their centers, so that the hologram disk 9 and the reflecting mirrors 37 and 40
and the relative distance to the scanning surface 12. Next, the intersection angle of the scanning lines 39 and 42 on the scanning surface 12 can be arbitrarily determined by selecting the incident angle of the scanning light to the reflecting mirrors 37 and 40 (the average incident angle because the incident angle changes depending on the scanning angle). . At this time, the larger the incident angle is, the larger the intersection angle can be.

It will be explained next that when the configuration shown in FIG. 3 is adopted, the scattered light from the object to be scanned can be collected without any problem. FIGS. 4a, b, c, and d are diagrams for explaining the convergence of scattered light in the optical reading device of this invention. Figures a, b, c, and d are cross-sectional views showing the hologram 31 of the hologram disk 9 in FIG. 3, with other holograms omitted. FIG. 4a shows a state in which the upper end of the hologram 31 in FIG. 3 is irradiated with the light beam 1. In FIG. 4a, scanning beam 43 is scanning scanning point 44. In FIG. Scattered light from the object to be scanned at the scanning point 44 exits in various directions, but the scattered light that reaches the hologram 31 is focused on the point 23 by the lens action of the hologram 31. The light focused on the point 23 is spatially separated from the light beam 1 by an anti-transparent mirror or a perforated mirror, photoelectrically converted, and information about the scanned object is detected. In this case hologram 31
In order for the scattered light to reach the top, the reflector 37 is sized and arranged to reflect the scattered light in the range between the scanning beam 43 and the scattered light 45 . Next, when the hologram disk 9 rotates in the direction of the arrow 11 and the hologram 31 comes to the position shown in FIG. A beam 46 is scanning a scanning point 47. Of the scattered light from the object to be scanned 47, the scattered light in the range between the scanning beam 46 and the scattered light 48 is reflected by the reflecting mirror 37, reaches the hologram 31, and is focused on the point 23. Figure 4c,
FIG. 4d shows that when the hologram disk 9 rotates further in the direction of the arrow 11, the scanning beam 49 scans the scanning point 50 to the scanning beam 52 scans the scanning point 53, and the scattered lights 51, 54 are scanned.
This is a diagram illustrating a case in which the light is reflected by a reflecting mirror 40 and condensed by a hologram 31, but since it is almost the same as the explanation for FIGS. 4a and 4b, the explanation will be omitted.

Next, a second embodiment of this invention will be described. FIG. 5 is a perspective view showing a second embodiment of this invention. In the embodiment of FIG.
Since everything other than the arrangement of 6 and 57 is the same as the first embodiment (FIG. 3), only the structure of the reflecting mirror will be described.
As in the first embodiment, one hologram, for example hologram 31, scans the scanning angle range indicated by arrow 43. The scanning beam is transmitted through reflecting mirrors 55, 5
6 and 57 and are reflected, forming a scanning pattern consisting of three intersecting scanning lines 58, 59, and 60 on the scanning surface 12. Since the scattered light from the object to be scanned is almost the same as that shown in FIG. 4 described above, the description thereof will be omitted. This embodiment allows scanning of three intersecting lines, and can also be applied to barcode reading devices for POS (point of sale) systems. The holograms used in these examples are usually produced by the interference of a spherical wave and a plane wave, but the hologram was produced by the interference of a diverging spherical wave and a converging spherical wave, as in the invention filed in Patent Application No. 53-11711 in 1971. Using holograms, the aberrations of the scanning beam are significantly smaller over large scanning angles.

With this invention, an optical reading device capable of cross-scanning with a large scanning line length without increasing the diffraction angle of the hologram and an optical reading device capable of three-line crossing can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a conventional optical reading device, FIGS. 2a, b, and c are diagrams for explaining the convergence of scattered light in the conventional optical reading device, and FIG.
4a, b, c, and d are diagrams for explaining the convergence of scattered light in the first embodiment. FIG. 5 is a perspective view showing the configuration of the first embodiment of this invention. FIG. 2 is a perspective view showing the configuration of a second embodiment of the present invention. In the figure, 1 is a laser beam, 2 to 8 and 3
1 to 36 are holograms, 9 is a hologram disk, 10 is a rotation center axis, 11 is a disk rotation direction, 12 is a scanning surface, 13, 16, 22, 27, 3
7, 40, 55, 56 and 57 are reflecting mirrors, 15,
18, 39, 42, 58, 59 and 60 are scanning lines, 19, 24, 43, 46, 49 and 52 are scanning beams, 21, 26, 45, 48 and 51 are scattered lights, 20, 25, 29, 30, 44, 47,
50 and 53 represent scanning points, respectively.

Claims (1)

[Scope of utility model registration request] A hologram disk in which a plurality of holograms are arranged on a circumference, a means for rotating the hologram disk, a light beam generator installed to irradiate the hologram, and a scanning beam from the hologram directed toward an object to be scanned. an optical reader for reading information on the object to be scanned, comprising means for reflecting, and means for detecting the light scattered by the object to be scanned, which is diffracted by the hologram participating in the scanning of the light on the hologram disk; In the apparatus, the means for reflecting the scanning beam onto the object to be scanned is a means for spatially dividing substantially the entire length of the scanning line by the hologram into scanning lines in a plurality of scanning directions. reader.