JP2706446B2 - Laser light scanning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Since signal scattered light C propagates while spreading between optical systems, a wide area must be secured as a traveling optical path for passing the light. Therefore, the signal light path is narrowed by a concave mirror having a curved surface on the inside, and the device is made thinner. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader that reads a bar code on a product, and more particularly to a laser beam scanning device that scans a laser beam in a desired direction. Bar code readers that can directly input data from a cash register to a computer are widely used in supermarkets and other fields as POS (point of sales) terminals that can collect sales data in real time. However, in a supermarket or the like, a plurality of barcode readers are often arranged side by side on the same cashier counter, and a reduction in the size of the apparatus is required from the viewpoint of freedom of layout and space saving. Particularly in supermarkets and the like in Europe where an operator operates a bar code reader while sitting down, there is a great demand for a thin device. As a means for realizing such a bar code reader, a laser beam scanning device used for the bar code reader is required to have a small occupied space and to be thin. [Prior Art] FIG. 2 is a schematic view showing a conventional laser beam scanning device. In FIG. 2 (a), a conventional laser beam scanning device comprises an optical scanning unit 1 composed of a rotating mirror or a hologram disk, a deflection system 2 composed of at least one plane mirror 21, a concave mirror 31, and a light detection unit. A laser beam A is converted into a scanning beam B in the optical scanning unit 1. The scanning light B generated in the optical scanning unit 1 is deflected by the deflection system 2, emitted from the reading window 4 to the outside of the apparatus, and irradiates the read medium 5 such as a barcode. The signal scattered light C from the medium to be read 5 generated by the irradiation of the scanning light B is guided to the signal detection system 3 via the deflecting system 2 and the optical scanning unit 1, and is detected by the photodetector 32.
Focus on As shown in FIG. 2 (b), the signal detection system 3 is composed of a condenser lens 33 and a photodetector 32, and the signal scattered light C from the optical scanning unit 1 is collected on the photodetector 32 by the condenser lens 33. You may light. [Problems to be Solved by the Invention] However, the signal scattered light C has a property of propagating while spreading inside the optical system, and if it is deflected by the plane mirror 21 and propagated, a wide area must be secured as a signal light path. . As a result the height h ₁ of the laser beam scanning device is increased, there is a problem that inhibits thinning of the bar code reader. [Means for Solving the Problems] FIG. 1 is a schematic view showing a laser beam scanning apparatus according to the present invention. The same object is denoted by the same symbol throughout the drawings. The above problem is that the laser scanning light is emitted through the reading window to irradiate the surface of the medium to be read, and the signal scattered light generated by the laser scanning light being reflected by the medium to be read is received through the reading window and detected by the light detector. In a laser beam scanning device for detecting, a laser beam A incident from a predetermined direction is converted into a scanning beam B for scanning in a predetermined direction by a rotation operation thereof, and a scanning beam B from the optical scanning unit 1 is converted. Is reflected toward the reading window 4, and the signal scattered light C incident from the reading window 4 is reflected toward the optical scanning unit 1 via at least one first concave mirror 22 and the optical scanning unit 1. A second concave mirror 31 for further reflecting the incident reflected light from the first concave mirror 22 and condensing the reflected light on the photodetector 32; the first concave mirror 22 extends the scanning direction of the scanning light B The direction perpendicular to the axial direction and the long axis direction is the short axis direction The problem is solved by the laser light scanning device of the present invention, which is a cylindrical concave mirror having a reflecting surface oriented in a short direction and having a reflecting surface curved in a short axis direction. [Operation] In FIG. 1, a deflecting system 2 for deflecting the scanning light B has a rectangular curved surface whose major axis is the scanning direction of the scanning light B and whose minor axis is a direction perpendicular to the scanning direction. By configuring with a curved cylindrical concave mirror 22,
The width in the height direction of the signal light path through which the signal scattered light C passes is reduced, and the height of the laser light scanning device is reduced, so that the bar code reader can be made thinner. Embodiment An embodiment of the present invention will be described below in detail with reference to FIG. In FIG. 1 (a), the laser beam scanning device according to the present invention comprises a light scanning section 1 constituted by a rotating mirror or a hologram disc and at least one first concave mirror 22 having a curved surface inside. Deflection system 2 and a second concave mirror
The laser beam A is converted into a scanning beam B in the optical scanning unit 1. The scanning light B generated by the scanning light generating unit 1 is deflected by the deflection system 2, emitted from the reading window 4 to the outside of the apparatus, and irradiates the read medium 5 such as a bar code. The signal scattered light C from the medium to be read 5 generated by the irradiation of the scanning light B is guided to the signal detection system 3 via the deflection system 2 and the optical scanning unit 1 and is collected on the photodetector 32. The signal scattered light C has a property of propagating while spreading, and when it is deflected by a plane mirror, it continues to spread even after being deflected. However, by deflecting this by a first concave mirror 22 having a curved surface inside, it is deflected. Signal scattered light C
Can be parallel, for example. As a result, the optical system that receives the signal scattered light C deflected by the deflection system 2, that is, the optical scanning unit 1 and the signal detection system 3 are reduced in height and thickness, and at the same time, the laser light scanning device is used. The interval in the height direction of the above-mentioned optical system can be reduced. By configuring the deflection system 2 with the first concave mirror 22 having a curved surface inside as described above, the width in the height direction of the signal light path through which the signal scattered light C passes is reduced, and the height of the laser light scanning device is reduced. is reduced to a conventional h ₁ is smaller than h _2, it is possible to reduce the thickness of the bar code reader. Moreover, it is more desirable to use, for example, a cylindrical concave mirror as the first concave mirror 22 having a curved surface inside in that the width of the scanning light B in the scanning direction is not reduced. As shown in FIG. 1B, the beam diameter of the scanning light B has a different reduction ratio between the vertical direction and the horizontal direction. There is no problem if the incident laser light A is corrected. Further, as shown in FIG. 1 (c), the signal detection system 3 is made thinner by using a concave mirror having a different radius of curvature in the vertical and horizontal directions as the second concave mirror 31 constituting the signal detection system 3. Signal scattered light C from the read medium
Can be condensed on the photodetector 32 with high efficiency. [Effects of the Invention] As described above, according to the present invention, it is possible to provide a laser beam scanning device that realizes a thin bar code reader.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a laser beam scanning device according to the present invention, and FIG. 2 is a schematic diagram showing a conventional laser beam scanning device. In the figure, 1 is an optical scanning unit, 2 is a deflection system, 3 is a signal detection system, 4 is a reading window, 5 is a medium to be read, 22 is a concave mirror, 31 is a concave mirror, and 32 is a photodetector.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hiroyuki Ikeda               Fujitsu, 1015 Ueodanaka, Nakahara-ku, Kawasaki-shi               Inside the corporation                (56) References: Japanese Utility Model Showa 54-70447 (JP, U)                 52-46636 (JP, U)

Claims (1)

(57) [Claims] The laser scanning light is emitted through the reading window to irradiate the surface of the medium to be read, and the laser scanning light is reflected by the medium to be read and the signal scattered light generated is received through the reading window and detected by the photodetector. A laser beam scanning device that converts a laser beam A incident from a predetermined direction into a scanning beam B that scans in a predetermined direction by rotating the laser beam A; Is reflected toward the reading window (4), and the signal scattered light C incident from the reading window (4) is reflected toward the optical scanning unit (1). And a second mirror for further reflecting the reflected light from the first concave mirror (22) incident through the optical scanning unit (1) and condensing the reflected light on the photodetector (32). And the first concave mirror (22) has a concave mirror (31). The scanning direction of the inspection light B is a major axis direction, a reflecting surface having a minor axis direction perpendicular to the major axis direction, and the reflecting surface is a cylindrical concave mirror curved in the minor axis direction. Laser light scanning device characterized by the above-mentioned. 2. The second concave mirror (31) has a reflecting surface whose major axis is a direction parallel to the scanning direction of the scanning light B and whose minor axis is a direction orthogonal to the major axis direction. 2. The laser beam scanning device according to claim 1, wherein the laser beam scanning device is curved in the major axis direction and the minor axis direction.