JPH0312291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hologram scanner that performs optical scanning using a hologram.

Recently, in order to save labor at registers at supermarkets, etc., barcode reading devices have come into use that read barcodes printed on the exterior of products and input them into computers.
A hologram scanner using a hologram is suitable for the optical scanning section of this barcode reading device, and therefore, this hologram scanner is often used.

FIG. 4 is a diagram for explaining the optical system configuration of a hologram scanner, and 1 shows a hologram 2 on two sides.
and 3 are equipped with a spinning top-shaped hologram rotating body (hereinafter referred to as holotop), 4 is a laser beam, 5a,
5b is a reflecting mirror, 6 is a window glass, 7 is a window cover,
, respectively indicate scanning light. In this hologram scanner, by rotating a holotop 1, a laser beam 4 is alternately incident on holograms 2 and 3, and scanning light is alternately emitted from a slit in a window cover 7. This scanning light is scattered and reflected by the bar code to become a scattered signal light 8, which travels in the opposite direction to the scanning light, enters the holograms 2 and 3, and is guided into the holotop. Further, this signal light is reflected and converged by a reflective Fresnel lens 9 provided in the holotop 1, and enters a photodetector 10 located at the center of the rotation axis, where the bar code is read. In such hologram scanners, technological development is progressing toward miniaturization and higher precision.

[Conventional technology]

In the above-mentioned conventional hologram scanner, the holotop directs the signal light 8 onto the photodetector 10 outside the holotop, or as shown in FIG.
2 to be focused on the detector 10.

[Problem that the invention seeks to solve]

In both of the above configurations, as shown in FIG. 6 (bottom view of the holotop), the ineffective portions 13 of the holograms 2 and 3 located at the center of the holotop are quite large. There were also problems such as considerable windage loss due to the large holes.

[Means for solving problems]

The present invention provides a hologram scanner that solves the above-mentioned problems, and its means is such that a laser beam incident on the inside of the rotating body is diffracted by a hologram attached to or formed on the rotating body, and the rotating body is rotated. While being emitted to the outside of the body, the emitted light functions as a scanning light for the object to be read by the rotation of the rotating body, and the signal scattered light from the object to be read by the scanning light is collected again by the hologram. The hologram scanner is of a type in which light is emitted and guided to a photodetector, and the hologram is disposed on the rotating body at a laser beam scanning/reading position, and the hologram is transmitted through the rotating body. The signal scattered light is passed through a signal scattered light passage hole provided close to the laser beam scanning/reading position of the rotating body, and the light detection unit installed on the rotation center axis outside the rotating body. A lens means for guiding the signal to the light detector, and a light condensing means is provided outside the rotating body between the passage hole and the photodetector, and the point of convergence of the signal scattered light by the lens means is located at the passage hole. matches,
In the hologram scanner, the signal scattered light becomes a diverging light that is emitted toward the outside of the rotating body from the convergence point, and is then guided to the photodetector by the light condensing means. It is done by hand.

[Effect]

The above-mentioned hologram scanner can make the hole smaller by aligning the signal light convergence point of the holotop with the hole at the lower end of the holotop, reducing the ineffective area of the hologram and reducing windage loss compared to the conventional method. reduction can be achieved.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram for explaining one embodiment of the present invention, in which a is a sectional view and b is a bottom view. In the figure, 20 is a holotop, 21 and 22 are holograms, 23 is a drive motor, 24 is a laser beam,
25 is a reflecting mirror, 26 is a scanning light, 27 is a signal light, 2
8 is a reflective Fresnel lens, 29 is a condensing lens,
30 each indicates a photodetector.

As shown in FIG. 1, this embodiment has holograms 21 and 22 for scanning and condensing laser beams on the slope of a top-shaped rotating body, and a reflective Fresnel lens 28, which is a lens means for condensing signal light, on the upper inner surface. Holotop 2
0, the small hole 3 centered on the rotation center axis
1 is provided in the holotops 21 and 22, the focal length of the reflective Fresnel lens 28 is set so that the signal hole 27 is converged on the hole 31, and
A condensing lens 29, which is a condensing means, is placed on the central axis of rotation away from 0, and a photodetector 30 is placed at the convergence point of the signal light condensed by the condensing lens 29.
is arranged.

In this embodiment configured in this way, the signal light 27
is displayed on the holotop 20 by the holograms 21 and 22.
Furthermore, a reflective Fresnel lens 28 is introduced into the
After being reflected by the hole 31 and converging on the hole 31, the light exits the holotop 20 and becomes a diverging light. This diverging signal light is focused onto a photodetector 30 by a condensing lens 29. In this case, since the hole 31 coincides with the convergence point of the signal hole, its diameter can be made much smaller than in the prior art.

Note that instead of the condenser lens 29, a hologram 32 as shown in FIG. 2 may be used, or a concave mirror 33 as shown in FIG. 3 may be used. In these cases as well, the hole 31 for signal light passage provided in the holotop 20 can be made small as in the previous embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, by aligning the signal light convergence point of the holotop with the hole at the bottom end of the holotop, the hole can be made smaller than before, and the ineffective area of the hologram is This has the effect of reducing windage and windage losses.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining one embodiment of the hologram scanner of the present invention, FIGS. 2 and 3 are diagrams for explaining other embodiments of the present invention, and FIG. 4 is a diagram for explaining a conventional hologram scanner. FIG. 5 is a diagram for explaining the scanner, FIG. 5 is a diagram showing an example of a conventional holotop, and FIG. 6 is a bottom view of the conventional holotop. In the figure, 20 is a holotop, 21 and 22 are holograms, 23 is a drive motor, 24 is a laser beam, 25 is a reflecting mirror, 26 is a scanning light, 27 is a signal light, 28 is a reflective Fresnel lens, and 29 is a condenser. 30 is a photodetector, 31 is a hole for passing signal light, 32 is a hologram, and 33 is a concave mirror.

Claims (1)

[Claims] 1. Laser light incident on the rotating body is diffracted by a hologram attached to or formed on the rotating body and emitted to the outside of the rotating body, and the emitted light also reflects the rotation of the rotating body. The hologram scanner functions as a scanning light for the object to be read by the hologram, and the signal scattered light from the object to be read by the scanning light is again focused by the hologram and guided to the photodetector. The hologram is disposed on the rotating body at the laser beam scanning/reading position, and the signal scattered light transmitted through the hologram is transmitted inside the rotating body at the laser beam scanning/reading position of the rotating body. Through a hole for passing signal scattered light provided close to the
Lens means for guiding the light to the photodetector installed on the rotation center axis outside the rotating body, and light condensing means provided outside the rotating body between the passage hole and the photodetector. The convergence point of the signal scattered light by the lens means coincides with the passage hole, and the signal scattered light becomes diverging light that is emitted toward the outside of the rotating body from the convergence point, and then the signal scattered light is emitted from the convergence point to the outside of the rotating body. A hologram scanner characterized in that light is guided to the photodetector by optical means.