JPS6029088B2 - optical scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning device in an optical reading device that optically scans and reads an object to be read using light emitted from a light source that emits colored light.

Recently, optical reading devices (POS terminal systems) have been introduced in department stores and supermarkets that print price tags consisting of barcodes consisting of spaces and bars that indicate product prices and types, and then optically scan and read the price tags. It is being put into practical use.

FIG. 1 shows a conventional example. This is a system for reading information about a product 8 with an object to be read attached to a reading window 6 on a table 7 when an article 8 comes to the reading window 6 on a table 7 using an optical scanning and sampling system provided in the object 1. The light 11 emitted from the laser 2 is reflected multiple times by the reflecting mirrors 3, and then enters the rotating reflecting mirror 4.

The light is reflected by the annular reflecting mirror group 5 and scans the scanning window 6. After the reflected light that has scanned the object to be read is received and detected by the photodetector 9, the information recognition circuit 10 performs reading recognition. A perspective view and a side view of this scanning operation are shown in FIGS. 2a and 2b.
FIG. 2a is a perspective view, in which the ray light 12 is transmitted through the rotating mirror 13.
AB after being reflected on one sheet 14 of the annular reflector group 5
When scanning C, the scanning table 15 is scanned ABC'.

FIG. 2b is a side view. A rotating mirror 13 is driven and rotated by a motor 17 via a belt 18. The laser beam is then reflected by the fixed annular reflector group 14 and scans the scanning body on the scanning table 15. A He-Ne gas laser is used as a light source for such an optical reading device, but the beam diameter of a He-Ne gas laser is usually 0.5 to 0.5 mm unless it is passed through a slit etc. at the risk of loss of light intensity.
0.8 skin, and the beam spread is about 1.5 mrad.

Generally, the width of the narrow bar of barcodes that are currently being used is about 0.22 to 0.33 feet, so in order to read the object by optical scanning, it is necessary to
．． The beam diameter must be about the size of a willow tree. Therefore, although not shown in the conventional example shown in FIG. 1, the optical lens system in which the laser light is received is usually searched for between the optical lens system and the rotating reflector. When the optical system is set so that the minimum beam is on the scanning surface 15, the trajectory of the minimum beam diameter is A' as shown in FIG. 3 due to the optical path difference between the fixed annular reflector 14 and the scanning surface.
EC' and a part of a circular arc.

Further, the optical path difference between the rotating reflecting mirror position D and the scanning point of the fixed reflecting mirror 14 is superimposed on the optical path difference, so that the actual trajectory of the minimum beam diameter takes A'FC' with the center part being more prominent. The laser beam is fitted into a beam with a diameter of 0.1, and it is possible to read objects with a beam diameter of up to, for example, 0.2 diameter under the beam spread angle at the minimum beam position. When , that range becomes the discussable size.

That is, it can be read if it is within a predetermined range above and below the dotted line A'FC' in FIG.

However, when the object to be read is very long or when the object to be read is to be read in a product with a curvature such as a can, restrictions are added to these conditions. The present invention is intended to eliminate such drawbacks in the optical reading device.

FIG. 4 shows an embodiment of the present invention.

In the present invention, one annular fixed reflecting mirror performs unidirectional scanning of the reading scanning surface 15, and for the unidirectional scanning, one reflecting mirror 16 is used to partially shift the optical path as shown in FIG. The objective is to correct the optical path difference up to 15 on the scanning surface by increasing the length of the optical path. That is, to explain with reference to FIG. 4, the laser beam from the rotating reflector position D first passes through the reflector 16.
Scan the reflective surface S and above from G to day.

After that, the reflecting surface S21 moves back in position and has a different reflection angle from the reflecting surface S so as to scan the same scanning plane →
J is scanned, and the reflective surface S is scanned again from K to L, completing one scan of the reading scanning surface 15. FIG. 5 shows the state on the scanning plane when such scanning is performed. The light reflected by the reflecting mirror 16 shown in FIG. 4 according to the present invention performs the scanning of AMNC' in FIG. 5 in contrast to the scanning of A'FC' in the case of FIG. 3. By performing such scanning, the scanning position of the minimum beam comes closer to the scanning surface.

In Fig. 4, an explanation was given of a device having two reflective surfaces S and S2, but as the number of these surfaces increases, the
The 4th beam scanning position in 5 becomes closer. By setting the scanning position of the maximum beam diameter parallel to the scanning surface and changing the imaging position of the lens system, the position of the minimum beam diameter can be set to be parallel to the scanning surface. It is possible to read floating objects or very long codes.

As is clear from the above explanation, by correcting the optical path difference, reading, which has been difficult in the past, becomes possible and the range of possible readings can be greatly expanded.

Brief explanation of figures Figure 1 is a configuration diagram of a conventional scanning inspection device, Figures 2 a and b are perspective views and side views of the optical deflection section of the conventional example, and Figure 3 is a
・Scanning locus diagram of the beam diameter position, FIG. 4 is a structural diagram of one reflecting mirror according to an embodiment of the present invention, and FIG. 5 is a scanning locus diagram of the maximum beam diameter of the reflecting mirror in FIG. 4. shows.

2...Laser, 3...Reflector, 4...
...Rotating reflector, 5...Fixed annular reflector group, 1
1, 12...Laser light, 6...Scanning window, 8...Object to be read, 9...Photodetector,
10...Recognition circuit, 14,16...Reflector, 1
8...Belt, 17...Motor, 1
5...Scanning surface ~S,,S2...Reflecting surface.

Meno spear 2 ★j diagram Figure 4 Chiku diagram

Claims (1)

[Claims] 1. A light source that generates a light beam, an optical lens system, a rotating reflector into which the light beam from the light source is incident through the optical lens system, and a rotating reflector arranged around the rotating reflector. As an optical scanning device in an optical reading device comprising a fixed reflecting mirror that reflects reflected light from an object toward a scanning surface, and a detection means that reads reflected light from an object placed opposite to the scanning surface, In order to configure one scanning beam formed on the scanning surface with one fixed reflecting mirror having a plurality of reflecting surfaces and to suppress the locus amplitude of the minimum scanning beam diameter on the scanning surface, The central reflecting surface of the fixed reflecting mirror is set to have a longer optical path from the rotating reflecting mirror than the reflecting surfaces on both sides, and the reflecting angle of the surface is set to
An optical scanning device characterized in that the angle is set to correct a change in scanning position due to an optical path difference with the other reflecting surface.