JP3654266B2 - Optical information reader - Google Patents

Description

[0001]
[Technology to which the invention belongs]
The present invention relates to an optical information reading apparatus for reading optical information such as a bar code and a two-dimensional code.
[0002]
[Prior art]
In recent years, optical information such as barcodes and two-dimensional codes has been increasingly printed directly on the surface of substrates such as glass and metal for industrial parts, in addition to those printed on paper. Used for quality control. Optical information marked on the surface of the substrate that hardly causes light diffusion when the surface is in a mirror state is obtained by imaging the light that is regularly reflected on the substrate from the light projecting means of the optical information reader. It is necessary to form an image and obtain an image by the difference in reflectance between the marking surface and the substrate surface. In an optical system that obtains an image by utilizing regular reflection on a surface with little diffusion, it is desired that the light is emitted from the surface substantially uniformly so as not to cause uneven brightness. Therefore, as shown in FIG. 5, conventionally, a large number of light emitting elements 13 such as light emitting diodes are arranged on the surface, and light is projected through a diffusion plate 14 for further diffusing light.
[0003]
[Problems to be solved by the invention]
In the conventional light projecting means in which a large number of light emitting elements are arranged on the surface and light is projected through a diffusion plate for further diffusing light, the light emitting elements are arranged at short intervals in order to obtain planar light emission. In order to obtain sufficient diffusion between the light emitting source and the surface where the illumination light is emitted from the diffusion plate, an interval is necessary. It is difficult to reduce the dimension in the thickness direction of the light emitting surface of the light projecting means by shortening the interval. The present invention solves the above problems.
[0004]
In order to solve the above problems, an optical information reader according to the present invention projects an exterior case, an opening provided in the exterior case so as to read the optical information, and the optical information. A light guide plate having a concavo-convex surface for guiding the light from the light source and irradiating the optical information with light, and an imaging unit for forming an image of reflected light from the optical information. In the optical information reading apparatus having a sensor that captures imaged light, the light guide plate has a surface with the irregularities, the opening side having a short side that is substantially the same as the opening width, and the light source side having an opening. Symmetrical trapezoidal shape with a longer side longer than the width, and a smooth surface placed on the reading surface of the opening, and substantially the entire field of view of the imaging unit where the optical axis is obliquely arranged on the reading surface The light from the uneven surface of the light guide plate is totally reflected before To image the sensor, in which are arranged substantially along the outer edge of the field of view of the imaging unit.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
According to the first optical information reader of the present invention, when the light from the light source is incident on the light guide plate, the light is repeatedly reflected on the surface of the light guide plate and diffused on the uneven surface and partially guided. The reflected light that is emitted from the light and irradiates the optical information with the projected light reflected by the optical information is imaged by the imaging unit, and the imaged light is captured by the sensor.
[0008]
According to the second optical information reader of the present invention, when the light from the light source is incident on the light guide plate, the light is repeatedly guided and diffused on the uneven surface opposite to the reflection on the surface of the light guide plate. The part exits from the surface and irradiates the optical information with light. The reflected light of the projected light reflected by the optical information is imaged by the imaging unit, and the imaged light is captured by the sensor.
[0009]
According to the third optical information reader of the present invention, when the light from the light source enters the light guide plate, the light is repeatedly reflected on the surface of the light guide plate and diffused on the uneven surface and partially guided. The reflected light that is emitted from the light and irradiates the optical information with the projected light reflected by the optical information is imaged by the imaging unit, and the imaged light is captured by the sensor. The surface of the light guide plate that is opposite to the surface that emits light and irradiates the optical information is painted so that the light is easily reflected to prevent light from leaking from the light guide plate.
[0010]
Hereinafter, an optical information reading apparatus according to an embodiment of the present invention will be described with reference to the drawings.
[0011]
(Embodiment)
FIG. 1 is a perspective view showing an embodiment of the present invention. FIG. 2 is a partially broken side view. FIG. 3 is a partially broken projection view seen from the arrow (a) in FIG.
[0012]
The optical information reading device 1 is configured to operate a reading opening 4 for reading optical information 3 such as a barcode and a two-dimensional code on the front part of the outer case 2 on the rear part of the outer case 2 in appearance. A grip 5 for a person to hold with his / her hand is disposed at the rear end of the outer case 2 and an outlet for a cable 6 for transferring data from the optical information 3 to a host computer.
[0013]
Inside the exterior case 2, as light projecting means for irradiating the optical information 3 with light, a plurality of light emitting diodes 7 that are light sources of illumination light, and light from the light emitting diodes 7 are guided and emitted from the surface. A light guide plate 8 for projecting light onto the optical information 3, a lens 9 as an imaging means for imaging the reflected light from the optical information 3, and a two-dimensional arrangement at the imaging position of the lens 9 The image sensor 10 having the received light receiving element and converting the image information of the optical information 3 formed into an image into an electrical signal, and electrically connected to the image sensor 10 to perform signal processing on the electrical signal converted from the image information In addition, a circuit board 11 for transferring the signal processed data to the host computer via the cable 6 is incorporated. 4A is a perspective view of the light guide plate 8, FIG. 4B is a side view of the light guide plate 8, and FIG. 4C is a front view of the light guide plate 8. The light guide plate 8 is molded from a resin such as transparent polycarbonate that transmits light, and the light from the light emitting diode 7 is incident from the upper surface (A) and is relative to the front surface (C) and the surface (C) having a large area. The surface of the back surface (d) that faces the surface is extremely uneven, and all surfaces including the back surface (d) other than the light incident surface (b) and the front surface (c) It is painted white. As shown in FIG. 4B, when viewed from the side, the thickness of the light guide plate on the incident side where the light from the light emitting diode 7 is incident is such that the light can be sufficiently incident from the light emitting diode 7. The side is thin and has a tapered shape. As shown in FIG. 4C, when viewed from the front, the reading port side is substantially the width of the reading port, and the incident side has a trapezoidal shape wider than the reading port side. A notch (e) on the incident side is a cause of interference with the imaging lens 9.
[0014]
The focus position A with the best resolution of the image formed on the image sensor 10 of the lens 9 is in the vicinity of the reading opening 4 of the outer case 2. The optical information 3 is obtained by direct marking by vapor deposition printing a metal film on the smooth surface of the glass substrate 12. In a state where the opening edge 13 of the opening 4 is brought into contact with the glass substrate 12 so as to cover the optical information 3 or slightly lifted as shown in FIG. 2, the optical information 3 is the in-focus position of the lens 9. An image with good resolution is formed on the image sensor 10 in the vicinity of A. The light guide plate 8 of the light projecting unit is in a state where the opening edge 13 is in contact with the glass substrate 12 or slightly floated, that is, the surface of the glass substrate 12 is in the vicinity of the focusing position A of the lens 9. In a state substantially parallel to the edge 13, the light B from which the light from the front surface (c) of the light guide plate 8 is totally reflected by the lens 9 on the surface of the glass substrate 12 illuminates substantially the entire field C of the lens 9. Are arranged as follows.
[0015]
In such a configuration, when the optical information 3 is covered with the opening edge 13 of the opening 4 in contact with the glass substrate 12 so as to cover the optical information 3 or slightly lifted, the light emitting diode 7 When the light enters the inside from the upper surface (a) of the light guide plate 8, the light is reflected on the surface of the light guide plate and diffused on the uneven surface of the front surface (c) and the back surface (d) to be uniform and partially Is emitted from the front surface (c) and projected onto the glass substrate 12 marked with the optical information 3. The light reflected from the glass substrate 12 is imaged on the image sensor 10 by the lens 9, and an optical information image is obtained by the difference in reflectance between the glass substrate surface and the metal deposition surface. The formed image is converted into an electric signal by the two-dimensionally arranged light receiving elements of the image sensor 10, and the circuit board 11 electrically connected to the image sensor 10 performs signal processing on the electric signal obtained by converting the image information. Then, the signal processed data is transferred to the host computer via the cable 6.
[0016]
In this embodiment, the front surface (c) of the light guide plate 8 and the back surface (d) opposite to the surface (c) are roughened by embossing, but the smooth surface is transparent. An uneven surface may be formed by applying a texture coating. Moreover, it is possible to make it difficult for the illumination light to leak even if a reflecting plate is arranged so as to cover the surface (D) instead of painting the back surface (D) white.
[0017]
【The invention's effect】
As described above, according to the present invention, when the light from the light source enters the light guide plate, the light is repeatedly reflected on the surface of the light guide plate and diffused on the uneven surface, and part of the light is emitted from the surface. To illuminate the optical information. By repeating reflection and diffusion in the light guide plate, the light is uniformly diffused, and the light emitting surface can be projected as a substantially uniform light emitting surface for optical information. Further, the light emitting surface of the light projecting means, that is, the dimension in the thickness direction of the light emitting surface is the thickness of the light guide plate and can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an optical information reader according to an embodiment of the present invention. FIG. 2 is a partially broken side view showing an optical information reader according to an embodiment of the invention. FIG. 4 is a partially broken projection view of the optical information reading device according to the embodiment of the present invention as viewed from the arrow (a) in FIG. 2; FIG. 4 (a) is a guide for the optical information reading device according to the embodiment of the present invention; (B) A side view showing the light guide plate of the optical information reading device according to the embodiment of the present invention. (C) The light guide plate of the optical information reading device according to the embodiment of the present invention. Front view shown [FIG. 5] Partially cutaway side view showing an embodiment of a conventional example [Explanation of symbols]
7 Light-emitting diode 8 Light guide plate 9 Lens 10 Image sensor 11 Circuit board

Claims (1)

An exterior case, an opening provided in the exterior case and opened to read optical information, a light source for projecting the optical information, light from the light source, and the optical information In the optical information reading device, comprising: a light guide plate having a concavo-convex surface for irradiating light; an imaging unit that forms an image of reflected light from the optical information; and a sensor that captures the imaged light. The light guide plate has a substantially trapezoidal shape in which the surface having the unevenness is a symmetrical trapezoidal shape having a short side whose opening side is substantially the same as the opening width and a long side longer than the opening width on the light source side The light from the uneven surface of the light guide plate is totally reflected with respect to a substantially entire area of the field of view of the imaging unit in which the optical axis is obliquely arranged on the reading surface with a smooth surface placed on the reading surface. In order to form an image on the sensor, the outer edge of the field of view of the imaging unit is substantially aligned. Optical information is arranged Te reader.

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