JP2004199266A - Bar code reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bar code reader that increases utilization rate of reflection light from a bar code in order to improve detection accuracy, with a miniaturized size and a reduced number of components. <P>SOLUTION: The bar code reader comprises a laser beam source 101, a photodetector 401, a light projecting optical system that leads laser beam 104 emitted from the laser beam source to the bar code 301, and a light receiving optical system that leads the reflection light 302 from the bar code to the photodetector 401. The light projecting optical system is equipped with a pivoting mirror 201 for scanning the laser beam 104 on the bar code, and the light receiving optical system comprises the pivoting mirror. The photodetector 401 is placed on a light beam axis X of a part from the laser beam source of the light projecting optical system to the pivoting mirror. The photodetector has an opening 401a so that the light beam axis and the part around it allow the laser beam 104 to pass, and a planate detecting surface perpendicular to the light beam axis X, which is fitted with a filter 402 to block the light outside a required wavelength range. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a barcode reader, and more particularly to a barcode reader having an integrated optical system for projecting and receiving light.
[0002]
Problems to be solved by the prior art and the invention
2. Description of the Related Art A system for attaching a barcode carrying information on a product to various products or its packaging to obtain information for management of production, distribution, storage, sale, and the like of the product is widely used. A bar code reader is used as a means for inputting information obtained by reading a bar code of an individual product into a management computer.
[0003]
The bar code reader irradiates the bar code with light, and detects the reflected light of the irradiation light by the bar code using a photodetector. This detection is performed by scanning the detection area along the direction of the bar array with respect to the barcode, and barcode information is reproduced as a time-series electric signal based on the output of the photodetector at that time. There are various means for scanning the detection area in the bar code reader, for example, scanning the irradiation position of a small width light beam such as a laser beam on the bar code along the bar array direction of the bar code, In such a case, light reflected from each irradiation position is guided to a photodetector.
[0004]
As described in, for example, JP-A-6-176181 (Patent Document 1) and JP-A-6-180766 (Patent Document 2), the scanning of the light beam irradiation position is performed by converting the entire barcode reader into a barcode. On the other hand, it can be performed by relatively moving manually. This method is advantageous for miniaturization because it does not require an optical means for scanning the light beam irradiation position in the bar code reader, such as a swing mirror. However, for example, in a cash register of a supermarket that reproduces barcode information of a large number of commodities, there is a drawback that an increase in scanning speed cannot be expected in a manual operation of moving a barcode reader.
[0005]
As another example of light beam irradiation position scanning, as described in, for example, JP-A-10-40328 (Patent Document 3) and JP-A-2000-231598 (Patent Document 4), An optical means for scanning the irradiation position of the light beam, such as a oscillating mirror and a rotating polygon mirror, is arranged at the position, and the optical path of the irradiation light beam is deflected by the optical means while the bar code reader is arranged in a stationary state. In some cases, scanning is performed by changing the deflection angle. According to this, the scanning speed can be improved.
[0006]
By the way, in order to use the irradiation light amount for detection as effectively as possible, it is preferable to make as much of the reflected light from the barcode as possible incident on the photodetector, and particularly incident on the photodetector over a required scanning range. It is preferable that the light quantity does not decrease. Therefore, as shown in FIG. 5 of Japanese Patent Application Laid-Open No. 2000-231598, for example, the reflected light in the widest possible range is converged on a photodetector using a condensing means such as a condensing lens. I have. However, the use of the light collecting means has a disadvantage of increasing the number of optical components. Also, in such a separate light emitting and receiving optical system in which a light projecting optical system for irradiating light and a light receiving optical system for guiding the bar code reflected light to the photodetector form separate optical paths, the optical detector is externally connected to the photodetector. Light may enter to lower the detection accuracy.
[0007]
In general, the light irradiation on the barcode is performed so that the irradiation light beam is incident substantially perpendicularly (in particular, such that the irradiation light beam is incident substantially perpendicularly to the center position of the scanning range). Therefore, if the photodetector is arranged so as to detect the reflected light that travels backward in the projection path of the irradiation light beam, the influence of external light can be reduced and the reflected light amount can be received efficiently. In a conventional bar code reader having such an integrated optical system for projecting and receiving light, a beam splitter or a partial reflecting mirror that reflects only a partial area is arranged in a portion from a laser light source to a scanning mirror of the projecting optical system. , The reflected light from the barcode is separated and guided to a photodetector arranged at a position distant from the optical path of the light projecting optical system.
[0008]
Alternatively, as shown in FIG. 3 of JP-A-2000-231598, the irradiation light beam is always vertically incident on the bar code over a required scanning range, and the principal ray of the reflected light follows the path of the incident light beam. The beam splitter is placed in the part from the laser light source to the scanning mirror of the light projecting optical system so that the reflected light from the bar code is separated and placed at a position away from the light path of the light projecting optical system. To the photodetector.
[0009]
However, when such a beam splitter or a partially reflecting mirror is used, the light amount loss at these reflecting means increases, the utilization rate of the bar code reflected light amount is reduced, and the detection accuracy may be reduced.
[0010]
Further, in such a structure, since the photodetector is disposed at a position deviated from the optical path of the light projecting optical system, it is difficult to reduce the size of the device.
[0011]
Further, there is a disadvantage that the number of components is increased by using the beam splitter or the partially reflecting mirror.
[0012]
In view of the above problems of the prior art, the present invention can improve the utilization rate of the reflected light amount of a barcode and thereby improve the detection accuracy, can reduce the size of the apparatus, and can reduce the number of parts. It is intended to provide a simple bar code reader.
[0013]
[Patent Document 1]
JP-A-6-176181 [Patent Document 2]
JP-A-6-180766 [Patent Document 3]
JP-A-10-40328 [Patent Document 4]
Japanese Patent Application Laid-Open No. 2000-231598
[Means for Solving the Problems]
According to the present invention, as achieving the above objects,
A bar code including a light source, a light detector, a light projecting optical system that guides light emitted from the light source to a bar code, and a light receiving optical system that guides reflected light from the bar code to the photo detector. In the reader,
The light projection optical system includes a scanning mirror for scanning light emitted from the light source on the bar code,
The light receiving optical system includes the scanning mirror,
A bar code reader, wherein the light detector is arranged on an optical axis of a portion from the light source of the light projection optical system to the scanning mirror,
Is provided.
[0015]
In one embodiment of the present invention, the photodetector is formed such that the optical axis and a portion near the optical axis allow passage of light emitted from the light source. In one embodiment of the present invention, the optical axis of the photodetector and a portion near the optical axis are openings. In one aspect of the present invention, the photodetector has a planar detection surface substantially orthogonal to the optical axis. In one embodiment of the present invention, a filter for blocking light outside a required wavelength range is provided on a detection surface of the photodetector.
[0016]
In one embodiment of the present invention, the light source is a laser light source. In one embodiment of the present invention, the light source is provided with a collimator lens. In one embodiment of the present invention, the light source is provided with an aperture limiting member having an aperture at and near the optical axis.
[0017]
In one embodiment of the present invention, the scanning mirror is a swing mirror or a rotating polygon mirror.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a schematic diagram showing an optical system of a barcode reader according to the present invention. In FIG. 1, reference numeral 101 denotes a laser light source, reference numeral 102 denotes a collimator lens, reference numeral 103 denotes an aperture limiting member, and reference numeral 104 denotes an opening 103a of the collimator lens 102 and the aperture limiting member 103 emitted from the laser light source 101. 2 shows a laser beam emitted through a laser beam. Reference numeral 201 denotes a swing mirror as a scanning mirror, and reference numeral 202 denotes a swing drive unit. Reference numeral 301 denotes a barcode (a barcode label or the like), and reference numeral 302 denotes reflected light from the barcode. Reference numeral 401 denotes a photodetector, and reference numeral 402 denotes a filter.
[0020]
The light projecting optical system that guides light emitted from the laser light source 101 to the bar code 301 includes a collimator lens 102, an aperture limiting member 103, and a swing mirror 201. Reference sign X indicates an optical axis of a portion from the laser light source 101 of the light projection optical system to the oscillating mirror 201. The opening 103a of the opening limiting member is located at the optical axis X and its vicinity. Further, the photodetector 401 is disposed on the optical axis X, and allows the light emitted from the laser light source 101 to pass through the opening 103a of the aperture limiting member in the optical axis and in the vicinity thereof. An opening 401a is formed. FIG. 2 is a plan view of the photodetector 401 viewed from the side of the oscillating mirror in the direction of the optical axis X. The photodetector 401 has a planar detection surface 401b substantially orthogonal to the optical axis X. Similarly, the filter 402 attached to the detection surface 401b of the photodetector is also disposed on the optical axis X, and the aperture 103a of the aperture limiting member emitted from the laser light source 101 is disposed near the optical axis. An opening 402a is formed to allow the passage of light passing through the aperture 402a. The opening 402a has the same shape and dimensions as the opening 401a. The filter 402 blocks external light outside the required wavelength range from entering the detection surface 401b of the photodetector. The required wavelength range includes the wavelength of light emitted from the laser light source 101.
[0021]
In FIG. 1, reference symbol Y indicates a rotation center axis of the swing mirror 201. The direction of the rotation center axis Y is perpendicular to the paper surface, and the swing mirror 201 is turned around the rotation center axis Y by the swing drive unit 202 as indicated by an arrow. As a result, the light beam 104 is scanned in the optical path from the rotating mirror 201 to the barcode 301, and the light irradiation position on the barcode 301 is scanned on the barcode 301 as indicated by an arrow. Note that the direction of each bar constituting the barcode 301 is perpendicular to the paper surface, and the direction of the bar arrangement is the same as the direction of the arrow for scanning the light irradiation position.
[0022]
The light receiving optical system that guides the reflected light from the bar code 301 to the photodetector 401 includes the above-mentioned oscillating mirror 201. That is, a part 302 of the diffuse reflected light from the light irradiation position of the barcode 301 is reflected by the oscillating mirror 201, reaches the photodetector 401 via the filter 402, and is detected. Note that FIG. 1 shows that the light reflected at the outer edge of the oscillating mirror 201 is incident on the outer edge of the photodetector 401. However, when the distance from the oscillating mirror 201 to the barcode 301 changes, these relationships are changed. Is changed, so that the size of the detection surface 401b of the photodetector is set to be larger than that shown in the figure, so that there is a margin so that all the reflected light from the oscillating mirror 201 reaches the photodetector 401. Is preferred. Thereby, the distance range from the barcode 301 which can be detected well to the barcode reader can be expanded.
[0023]
In the above embodiment, since there is no reflecting member between the oscillating mirror 201 and the photodetector 401, the barcode reflected light 302 passes through the filter 402 immediately after being reflected by the oscillating mirror 201. Incident on the photodetector 401 and a decrease in the amount of incident light at that time can be minimized, so that the detection accuracy can be maintained well. Also, the number of parts can be reduced. Further, since the photodetector 401 is arranged on the optical axis X, the size of the barcode reader can be reduced.
[0024]
In the above embodiments, a laser light source is used as a light source. However, in the present invention, another light source such as a light emitting diode can be used as long as required light intensity and light amount can be obtained. As the scanning mirror, other mirrors, for example, a rotating polygon mirror, can be used other than the swing mirror.
[0025]
【The invention's effect】
As described above, according to the present invention, by arranging the photodetector on the optical axis of the portion from the light source of the light projecting optical system to the scanning mirror, it is possible to improve the utilization rate of the barcode reflected light amount, and A bar code reader capable of improving detection accuracy, reducing the size of the device, and reducing the number of components is provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an optical system of a barcode reader according to the present invention.
FIG. 2 is a plan view of a photodetector of the bar code reader of FIG.
[Explanation of symbols]
101 Laser light source 102 Collimator lens 103 Opening limiting member 103a Opening 104 Outgoing laser beam 201 Swing mirror 202 Swing drive 301 Barcode 302 Barcode reflected light 401 Photodetector 401a Opening 401b Detection surface 402 Filter 402a Opening X Optical axis Y Rotation center axis

Claims (9)

A bar code including a light source, a light detector, a light projecting optical system that guides light emitted from the light source to a bar code, and a light receiving optical system that guides reflected light from the bar code to the photo detector. In the reader,
The light projection optical system includes a scanning mirror for scanning light emitted from the light source on the bar code,
The light receiving optical system includes the scanning mirror,
A bar code reader, wherein the light detector is arranged on an optical axis of a portion of the light projecting optical system from the light source to the scanning mirror. The bar code reader according to claim 1, wherein the light detector is formed such that the optical axis and a portion near the optical axis allow passage of light emitted from the light source. The barcode reader according to claim 2, wherein the optical axis of the photodetector and a portion near the optical axis are openings. The barcode reader according to any one of claims 1 to 3, wherein the photodetector has a planar detection surface substantially orthogonal to the optical axis. The barcode reader according to claim 4, wherein a filter for blocking light outside a required wavelength range is provided on a detection surface of the photodetector. The bar code reader according to claim 1, wherein the light source is a laser light source. The bar code reader according to claim 1, wherein the light source is provided with a collimator lens. The bar code reader according to any one of claims 1 to 7, wherein the light source is provided with an opening limiting member having an opening in the optical axis and in the vicinity thereof. The barcode reader according to any one of claims 1 to 7, wherein the scanning mirror is a swing mirror or a rotating polygon mirror.

Images