JPH0312295B2 - - 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 the hologram of the present invention.

Recently, in order to save labor at registers in 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. Conventionally, this hologram scanner collects signal scattered light using a disk-type hologram, and then assembles individual optical components such as a perforated mirror, Fresnel lens, and filter in order to guide the signal light to a detector. It is necessary to construct a re-imaging optical system, which has been an obstacle to miniaturization. For this reason, a holotop type scanner has been devised in which an optical system for laser aperture scanning and re-imaging of signal scattered light on a detector is integrated in a spinning top-shaped rotating body.

[Conventional technology]

FIG. 5 is a diagram showing the main parts of a conventional holotop type hologram scanner. Holograms 2 and 3 are provided on the bottom slope of a hollow top-shaped rotating body 1, and a reflective Fresnel lens 4 is provided inside the top to form a hologram rotating body (holotop) 5, which is rotated by a motor 6 of this holotop 5. Just like that, a laser beam 8 enters from the slit 7 via a mirror 9, is alternately diffracted by the holograms 2 and 3, and becomes a scanning beam 10.
emits. Also, the scattered signal light 1 from the barcode
After entering the holograms 2 and 3 and being diffracted, the light is focused on a photodetector 12 by a reflective Fresnel lens 4, and the bar code is read.

[Problem that the invention seeks to solve]

Although the holotop 5 of the above structure has been made smaller, it has the disadvantage that windage loss during rotation is large because its shape is not a perfect rotating body as shown in FIG.

[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. It is a hologram scanner of a type in which light is emitted and guided to a photodetector, and the rotating body has a hollow cylindrical shape rotatable around a rotation axis, and the hologram is arranged at a laser beam scanning/reading position at the bottom of the rotating body. At the top thereof, the signal scattered light that passes through the hologram and passes through the rotating body is reflected, and the light that passes through the rotating body again and is placed on the rotation center axis outside the rotating body is reflected. This is done by a hologram scanner characterized in that it is provided with lens means leading to the detector.

[Effect]

In the above-mentioned hologram scanner, the hologram rotating body is formed into a hollow cylinder shape with a hologram disk attached to the bottom, so that the hologram rotating body becomes a complete rotating body and windage loss during rotation can be reduced.

〔Example〕

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

FIG. 1 shows a main part of an embodiment of the present invention as a sectional view. In the figure, 20 is a motor, 21 is its shaft, 22 is a holotop, 23 is a hollow cylindrical rotating body, 24 is a hologram disk, 25 is a filter/lens, 26 is a reflective Fresnel lens, 27
indicate a photodetector, respectively.

In FIG. 1, a hologram disk 24 is attached to the bottom of a hollow cylindrical rotating body 23, and a reflective Fresnel lens 26 is provided inside the top. Note that a lens 25 that also serves as a filter is provided at the center of the hologram disk 24. Further, the hologram disk 24 has two parts as shown in FIG.
Even if it has two facets 24 _-1 and 24 _-2 ,
Alternatively, as shown in FIG. 3, it may have a large number of facets _24-1 to _24-o .

The operation of this embodiment will be explained below. When the laser beam 28 for generating scanning light is input into the holotop 22 from the slit 30 via the mirror 29, the scanning light 31 is emitted from each facet of the hologram disk 24.
is emitted. Further, the scattered signal light 32 from the barcode is diffracted by each facet of the hologram disk 24 and becomes parallel light, and then focused on the photodetector 27 by the reflective Fresnel lens 26 and the filter/lens 25, and the barcode is detected. be read.

According to this embodiment, since the holotop 22 is a completely rotating body, the windage loss during rotation is reduced compared to the conventional holotop as shown in FIG.

Next, another embodiment of the present invention will be described with reference to FIG. In this figure, the same parts as in FIG. 1 are designated by the same reference numerals.

This embodiment differs from the previous embodiment in that the signal light converged by the reflective Fresnel lens is received by a filter/lens provided at the center of the hologram disc. In this embodiment, as shown in FIG. 4, the signal convergence light is guided from the reflective Fresnel lens 26 to the photodetector installed while maintaining an appropriate space between the two, and the bragging condition is removed. Therefore, the hologram on the hologram desk 24 is passed through and guided to the photodetector 27, thereby eliminating the need for a filter/lens. This embodiment has the advantage that the thickness T of the holotop 22 can be made thinner than in the previous embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, by using the hologram provided on the holotop as a disk, the holotop can be made into a completely rotating body, and the effect of reducing windage loss during rotation is significant.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining one embodiment of the hologram scanner of the present invention, FIG. 4 is a diagram for explaining another embodiment of the present invention, and FIG. 5 is a diagram for explaining a conventional hologram scanner. FIG. 6 is a cross-sectional view of a main part for explaining the scanner, and a perspective view of its holotop. In the figure, 20 is a motor, 21 is a shaft, 22 is a holotop, 23 is a hollow cylindrical rotating body, 24 is a hologram disk, 25 is a filter/lens, 26 is a reflective Fresnel lens, and 27 is a photodetector.

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 rotating body has a hollow cylindrical shape that can rotate around a rotation axis, the hologram is disposed at the laser beam scanning/reading position at the bottom, and the inside of the rotating body is transmitted through the hologram at the top of the hologram. and a lens means for reflecting the signal scattered light passing through the rotary body and guiding it again through the interior of the rotary body to the photodetector installed on the rotation center axis outside the rotary body. A hologram scanner.