JP2576604B2 - Laser light scanning device - Google Patents

Description

The present invention relates to a laser beam scanning device for reading a bar code or the like using a hologram and a laser beam, and more particularly to a hologram scanner capable of reducing the size and thickness of the device. The objective is to generate a multi-directional scanning pattern on the hologram window without using divided side mirrors by diffracting the scanning light from A reading window is formed by a hologram window having a plurality of transmission band holograms, and laser scanning light emitted outside the apparatus passes through the hologram window and is deflected by the band hologram to irradiate a medium to be read. In the laser beam scanning device which becomes the scanning beam to be scanned, the laser scanning beam incident on the hologram window is used for horizontal scanning of a plurality of parallel rows. Deflecting means for scanning a laser beam so as to form a turn, and scanning each of the band-shaped holograms of the hologram window by diffracting incident laser light from the deflecting means in directions different from each other and arranged corresponding to the plurality of rows. And a reflection type hologram that emits light as described above.

[Industrial applications]

The present invention relates to a laser beam scanning apparatus that reads a hologram and a bar code or the like using a laser beam, and more particularly to a hologram scanner that can reduce the size and thickness of the apparatus.

As a laser scanner that scans a laser beam in accordance with a desired pattern, there is a hologram scanner using a hologram in a scanning unit. By using such a hologram scanner, it is possible to form a complicated scanning pattern with a simple optical system, and it is possible to realize a bar code reader having a large reading depth.

Such a hologram scanner is widely used in supermarkets and other fields as a POS (Point of Sales) terminal capable of directly inputting data from a cash register to a computer and collecting sales data in a clear time.

However, in supermarkets and the like, devices are often installed on cashier counter tables together with cash registers and the like, and barcodes are read while moving goods in hand, from the viewpoint of layout flexibility, space saving and operator operability. There is a demand for smaller and thinner devices.

[Conventional technology]

FIG. 3 is a schematic view showing a conventional laser beam scanning device, and FIG.
The figure is a perspective view showing a conventional fixed hologram.

In FIG. 3, the conventional hologram scanner is a motor 11
And a hologram disk 12 having a plurality of holograms
, A mirror 13, a fixed hologram 2, a window cover 14, and a reading window 15 (corresponding to the portion of the fixed hologram 2 exposed by the opening 14a of the window cover 14).
The scanning light 16 deflected by the hologram disk 12 enters the fixed hologram 2 via the mirror 13. The scanning light 16 incident on the fixed hologram 2 is further deflected and focused on the bar code 17 of the medium 1 to be read from the reading window 15 through the opening 14a.

Further, the reflected light, that is, the scattered signal light 18 in the bar code 17 is propagated through the optical path in the direction opposite to the scanning light 16 and enters the hologram disk 12 as shown by the broken line,
The bar code 17 is condensed on a light detector (not shown) by 12 and is read.

The signal scattered light 18 enters the fixed hologram 2 while diverging, but does not spread greatly because the fixed hologram 2 is close to the barcode 17. Moreover, since the light is converted into a plane wave by the fixed hologram 2 and is incident on the hologram disk 12, there is an advantage that the condensing portion of the hologram disk 12 can be downsized.

In such a hologram scanner, light for scanning the surface of the bar code 17 is called a scanning line, and the scanning light 16 incident on the fixed hologram 2 is deflected in a plurality of directions in order to scan the surface correctly regardless of the direction of the bar code 17. Thus, a plurality of scanning lines are formed.

That is, as shown in FIG.
The hologram diffraction gratings 22, 23, 24 are formed in the reading window 15 corresponding to the scanning lines, and a plurality of intersecting scanning lines 220, 230,
A scan pattern including 240 is formed.

However, if the reading window formed in the window cover is close to the fixed hologram as shown in FIG. 5 (a), if the bar code 17 is inclined, it can be moved from top to bottom in the figure. Depending on the position where the barcode 17 passes, it may not be possible to read. For example, the barcode 17 passing through the position indicated by で is readable, but the barcode 17 passing through the position indicated by で is unreadable. Therefore, it is necessary to provide a reading window at the position where the scanning lines 220, 230 and 240 cross as shown in FIG. 9 (b). In the conventional hologram scanner, the distance h from the position where the scanning lines 220, 230 and 240 intersect to the fixed hologram 2 is at least 100 mm.
However, there is a problem that the thickness of the hologram scanner is hindered.

In order to solve such a problem, the present applicant has previously proposed a laser beam scanning apparatus using a hologram window as shown in FIGS. 6 and 7 in Japanese Patent Application No. 61-239903.

 FIG. 6 is an exploded perspective view showing the main structure.

In the figure, reference numeral 8 denotes a hologram window, which is formed by bonding three transparent substrates 44, 45, 46 having strip holograms 41, 42, 43 formed in different directions to each other so that the strip holograms cross each other. It is.

Then, the hologram window 8 is 3
The side mirrors 51, 52, 53, a concave mirror 55 having a through hole 54 and having a curved reflecting surface on the inner surface, a bottom mirror 56, and a light detector 5
7. It is installed on optical components such as a side mirror 58 for condensing light on the photodetector 57, a rotating polygon mirror 59 having five reflecting mirror surfaces, and a motor 60 for rotating the polygon mirror 59.

The optical components are a He-Ne laser 61 and a reflection mirror 62.
The laser beam scanning device is mounted on a base (not shown) in a predetermined positional relationship.

 Next, the operation will be described with reference to FIG.

As shown in FIG. 7A, a laser beam generated by a laser 61 is deflected by a reflection mirror 62 (see FIG. 6) and is a polygon mirror 59.
From the side to the concave mirror 55 side. The emitted light is reflected by the rear mirror 63 through the through hole 54, and is emitted again to the polygon mirror 59 through the through hole 54. This emission is scanned over a predetermined range by the inclination and rotation of the reflection surface of the polygon mirror 59, and sequentially scans the three side mirrors 51, 52, 53 (in the figure, the state where the scanning is performed on the center side mirror 52 is shown). (Shown) laser scanning light. Laser scanning light is mirror 5
It is emitted to the hologram window 8 via 1, 52, 53 and the bottom mirror 56, and sequentially scans three band-shaped holograms having different directions. Then, the emitted light is emitted as a scanning line in a predetermined direction by the band-shaped hologram, and a desired scanning pattern is formed by the emitted light.

Also, the signal scattered light from the bar code is emitted to the side mirror 52 via the reverse optical path of the scanning pattern, ie, →, and then the reflected light from the mirror 52 is transmitted through the polygon mirror 59 as shown in FIG. The emitted light emitted to the curved surface of the concave mirror 55 and condensed on the curved surface is detected by the photodetector 57 as signal light via the side mirror 58.

Thus, the scanning light from the polygon mirror is reflected by the three side mirrors and the bottom mirror arranged so as to cover the scanning angle, and the band hologram on the hologram window is sequentially scanned from the lower surface in the direction of the band, Laser light is emitted in a predetermined pattern above the hologram window by the diffraction effect of the band-shaped hologram, and the bar code is irradiated.

In the laser beam scanning device having the above configuration, the laser beam is emitted such that scanning patterns having different directions intersect on all planes above the hologram window.
The thickness of the device can be reduced without the need for a device.

[Problems to be solved by the invention]

However, in the above-described conventional laser beam scanning apparatus, three horizontal side-divided side mirrors are planarly incorporated below the hologram window in order to generate three different scanning patterns on the hologram window. There is a need. Since the side mirrors on both sides of the three surfaces are arranged so as to protrude to the outside of the hologram window, the outer shape of the device must be made larger than the size of the hologram window, and the device cannot be made compact. Was.

The present invention has been made in view of the above problems, and diffracts a scanning light from a rotating polygon mirror with a reflection hologram, thereby forming a three-directional scanning pattern on a hologram window without using a divided side mirror. An object of the present invention is to reduce the size of the apparatus by generating the light.

[Means for solving the problem]

FIG. 1 is a bottom perspective view showing a main part of a laser beam scanning device according to the present invention. The same object is denoted by the same symbol throughout the drawings.

The above problem is that a reading window is formed in the hologram window 8 having a plurality of transmission-type band-shaped holograms 81a, 82a, and 83a crossing each other. Through and the strip hologram
In a laser beam scanning device which is deflected by 81a, 82a, and 83a and becomes scanning light for irradiating a medium to be read, a laser scanning beam incident on the hologram window 8 is a plurality of rows of horizontal scanning patterns 34, 35 parallel to each other. And deflecting means 59 that scans the laser light so as to become 36, arranged in correspondence with the plurality of rows, diffracts the incident laser light from the deflecting means 59 in different directions from each other, and the band-like hologram 81a of the hologram window. The problem is solved by the laser light scanning device of the present invention, which is generated by reflection-type band-shaped holograms 31, 32, and 33 that emit light so as to scan each of 82a and 83a.

[Action]

When a plurality of reflection-type holograms 31, 32, and 33 have different diffraction directions and are formed in a predetermined manner, and are sequentially scanned by the scanning light from the deflecting means 59, the corresponding holograms on the reading window 8 have a desired scanning pattern. The light can be emitted to 81a, 82a, and 83a.

The scanning light from the deflecting means 59 is a reflection type band hologram 3
Since the light is reflected and diffracted by the light beams 1, 32, and 33 and is directly incident on the reading window 8, the deflection angle of the deflecting means 59 can be reduced, so that the side mirror and the bottom surface mirror are not required, and the device can be reduced in size and thickness.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

An exploded perspective view showing an embodiment of the present invention shown in FIG. 2 will be described with reference to FIG.

In FIG. 2, reference numeral 8 denotes a hologram window, 3 denotes a reflection hologram, 55 denotes a concave mirror having a through hole 54 and a curved reflecting surface, 59 denotes a rotating polygon mirror, 60 denotes a motor for rotating the rotating polygon mirror, and 61 denotes a motor. A laser light source, 57 is a light detector, and 58 is a side mirror for condensing light on the light detector.

The laser light is first emitted from a laser light source 61 such as a He-Ne laser, deflected by a reflection mirror 62, reflected by a rear mirror (not shown) behind the through hole 54 of the concave mirror 55, and directed in the direction of the reflection hologram 3. From the polygon mirror 59. The rotating polygon mirror 59 is made of, for example, a polygon having six faces, and the three-stage strip-shaped hologram 31 of the reflection hologram 3 is formed by slightly changing the emission angles in the height direction of the laser light incident from the same direction. , 32, and 33 are successively scanned within the same deflection angle range, and the three adjacent reflecting surfaces on the outer periphery of the polygon mirror have different inclinations with respect to the rotation axis.

The reflection type hologram 3 is provided below the hologram window, and has three reflection type band-shaped holograms 3 having different diffraction directions.
1, 32, 33 are vertically arranged in the same plane, and each hologram diffracts scanning light incident from the direction of the rotary polygon mirror 59, and strip holograms 81a, 82a,
A hologram is formed so as to irradiate 83a from below.

The hologram window 8 is formed by laminating three transparent substrates 81, 82, 83 such as glass having transmission-type strip holograms 81a, 82a, 83a having different directions so as to cross the strip holograms 81a, 82a, 83a. The hologram window 8 is formed so as to diffract laser light incident from a predetermined direction on the lower surface, transmit the diffracted laser light to the upper surface, and emit laser scanning light in a predetermined scanning pattern above the hologram window 8. Next, the operation of the reflective hologram 3 which is a feature of the present invention will be described with reference to FIG.

As described above, when the scanning light is sequentially radiated from the rotating polygon mirror (deflecting means) 59 to the band-shaped hologram of a plurality of stages, the scanning light is deflected and scans the hologram window in a predetermined scanning pattern as described below.

For example, in the present embodiment, first, the upper band hologram 31
Is scanned by a certain reflection surface of the rotary polygon mirror 59 as in the scanning pattern 34, the laser light diffracted and reflected obliquely upward is scanned in a scanning pattern substantially parallel to the surface of the reflection hologram 3 in the hologram window 8. The hologram 81a is scanned.

Next, when the band hologram 32 at the middle stage is scanned on the reflection surface next to the rotary polygon mirror 59 as shown in the scanning pattern 35, the laser beam is twisted and reflected, and scans the oblique band hologram 83a on the hologram window 8 this time. Is emitted.

Further, the light is deflected by the third reflecting surface of the rotary polygon mirror 59 and is incident on the lowermost band-shaped hologram 33 to be scanned.
The laser beam scanned as indicated by 56 is twisted and reflected in the direction opposite to the above-mentioned middle stage, and the hologram 82 in the hologram window 8 is reflected.
It is emitted as if scanning a.

The scattered signal light from the bar code follows the optical path opposite to the scanning light, enters the reflection type hologram 3 from the hologram window 8 and becomes a signal light having a constant direction from the rotating polygon mirror 59 to become a concave mirror mirror 55 (FIG. 2). Out). Since this signal light has a certain extent, unlike the scanning light, it is condensed by a concave reflecting surface having a large area, becomes converged light, is deflected by the side mirror 58, and is detected by the photodetector 57 at the focal position.

With the above configuration, since the scanning range of the rotating polygon mirror is small, there is no need to provide side mirrors or bottom mirrors on both sides, and it is easy to achieve a small and thin device.

〔The invention's effect〕

As described above, according to the present invention, in a laser scanning device capable of reducing the thickness of a barcode reading device, the side mirror and the bottom mirror that hinder the miniaturization of the device are not required.
It is possible to provide a smaller and thinner device as a whole.

[Brief description of the drawings]

FIG. 1 is a bottom perspective view showing a main part of a laser beam scanning device of the present invention, FIG. 2 is an exploded perspective view showing an embodiment of the present invention, FIG. 3 is a schematic diagram showing a conventional laser beam scanning device, FIG. 4 is a perspective view showing a conventional fixed hologram, FIG. 5 is a view showing a problem in a conventional laser beam scanning device, and FIG. 6 is an exploded perspective view showing a main configuration of a laser beam scanning device using a hologram window. FIG. 7 is a schematic side view showing an optical path state of the FIG. 6 apparatus. In the figure, 3 ... reflection hologram, 31,32,33 ... reflection band hologram, 34,35,36 ... horizontal scanning pattern, 51,52,53 ... side mirror, 55 ... concave mirror , 56 ... Bottom mirror, 57 ... Photodetector, 59 ... Rotating polygon mirror (deflection means), 60 ... Motor, 61 ... Laser light source, 8 ... Hologram window, 81a, 82a, 83a ... Transmission Type hologram,

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumio Yamagishi 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Hiroyuki Ikeda 1015 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (1)

(57) [Claims] A reading window is formed by a hologram window (8) having a plurality of transmissive band-shaped holograms (81a, 82a, 83a) crossing each other, and a laser scanning light emitted outside the apparatus is provided. In a laser beam scanning device which passes through a hologram window (8) and is deflected by said strip-shaped holograms (81a, 82a, 83a) to become scanning light for irradiating a medium to be read, a laser beam scanning said hologram window (8) A deflecting means (59) for scanning the laser beam so that the light has a plurality of parallel horizontal scanning patterns (34, 35, 36); and a deflecting means (59) arranged corresponding to the plurality of rows. The reflection-type hologram (3) which diffracts the incident laser light from the hologram in different directions and emits it so as to scan each of the holograms (81a, 82a, 83a) of the hologram window.
1, 32, 33).