JPH07249093A - Reader for bar code symbol - Google Patents

Abstract

PURPOSE:To automatically and securely read a multi-stage bar code symbol by projecting light, emitted from plural light sources into individual divided areas of the bar code symbols with time differences. CONSTITUTION:To read the multi-stage bar code symbol 4, this reader is equipped with a scanning mirror 1, three light sources 2, and a photodetector 3. A raster scan is made by shifting the axis of rotation of the scanning mirror 1 and the light sources 2 are made multiple and made different installation direction to project the light from each light source into a mutually different area of the bar code symbol 4; and the light sources 2 repeat turned-on operation one after another and the multistage bar code symbol 4 is read with the lights from the light sources 2. The light sources 2 are arranged in the specific directions and the light emitted by the light sources 2 is projected into the different areas of the bar code symbol 4 in order respectively with time differences. Therefore, the bar code symbol can securely be read without increasing the number of the reflecting surface of the scanning mirror 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention projects light emitted from a light source and reflected by a scanning mirror toward a multi-stage bar code symbol, and receives light reflected by the bar code symbol at a light receiving section. The present invention relates to a barcode symbol reading device that reads a signal output from a light receiving unit and reads information described in the barcode symbol.

[0002]

2. Description of the Related Art For example, as a reading device for reading a bar code symbol, a semiconductor laser serving as a light source, a polygon mirror for reflecting a laser beam from the semiconductor laser into scanning light, and a bar after being reflected by the polygon mirror. There is known a device including a photodiode that receives reflected light reflected by a code symbol and returns, and outputs a signal. Further, among the barcode symbol readers, there is known one in which the rotational position of the polygon mirror is provided slightly deviated from the central axis thereof, and raster scanning is performed by this.

[0003]

By the way, among the bar code symbols to be read by such a reading device, the bar code is described in a plurality of stages, that is, two-dimensionally (hereinafter referred to as a multi-stage bar code symbol. ) Has been proposed, and in the case of the reading device having the above-mentioned configuration, it is difficult to automatically read even if the number of reflecting surfaces of the polygon mirror is increased and raster scanning is performed.
For example, in the case of reading a bar codecivore composed of N-stage bar codes, at least as many scanning lights as the number of stages N are required, and even if one line is out of the bar code, an accurate reading operation cannot be performed. Therefore, in view of the above circumstances, it is an object of the present invention to provide a barcode symbol reader capable of automatically and reliably reading a multi-stage barcode symbol.

[0004]

That is, according to the present invention, light emitted from a light source and reflected by a scanning mirror is projected toward a multi-stage bar code symbol, and light reflected by the bar code symbol is received by a light receiving section. Which is a barcode symbol reading device for reading the information output from the light receiving unit and reading the information described in the barcode symbol,
Raster scanning is performed by displacing the rotation axis of the scanning mirror, the light source is composed of a plurality of light sources, and the installation directions of the light sources are different so that light from each light source is projected to different areas of the barcode symbol. The lighting operation of the light source is repeated one by one, and the multi-stage bar code symbol is read by light from a plurality of light sources.

[0005]

According to the present invention, a plurality of light sources are installed in a specific direction, and the light emitted from these light sources is projected to different areas of the bar code symbol with a time lag, whereby a scanning mirror is provided. It is possible to read reliably without increasing the number of reflective surfaces.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view showing a bar code symbol reading apparatus according to the present invention. This bar code symbol reading device is adapted to read a multi-stage bar code symbol 4, and includes a scanning mirror 1, three light sources 2, and a light receiving element 3.

The scanning mirror 1 is a polyhedron whose rotation axis 1A is displaced from the central axis by a predetermined angle α (rad) for performing raster scanning (for example, a regular hexagonal section in this embodiment).
It has a reflective surface 11 on the side of the
The light beams emitted from the respective light sources 2 are respectively reflected by the reflecting surface 11 on the side surface side and then raster-scanned on the multi-stage bar code symbol 4. In addition, as shown in FIG. 2, the scanning mirror 1 is configured so that at least one (or a plurality of) reflecting surfaces 11 can irradiate the beam light onto all the bar codes 40 in one step without leaking. Assuming that the distance between the barcodes 40 is W and the inclination angle difference between adjacent reflecting surfaces is Δα, the following formula is satisfied from the principle of optical leverage as well known, that is,

[0008]

[Equation 1]

It is necessary that The scanning mirror 1 is rotationally driven by a motor 12 controlled by a control unit 5 (see FIG. 4) described later.

The light source 2 includes a first light source 2A to a third light source 2C.
In this embodiment, a semiconductor laser (L
D) is used. Then, the light beams from the first light source 2A to the third light source 2C are transmitted through the collimating lenses 21A to 21C to be collimated, respectively, and then are divided into three areas of the multi-stage barcode symbol 4 in the first area A1 to the third area A1. The light is projected toward the three areas A3.

Therefore, as shown in FIG. 3, the first light source 2A to the third light source 2C are accurately aligned and mounted on a mount base 22 formed in a predetermined shape. The mount base 22 includes the second light source 2B and the reflection surface 11
Is D, and the angles formed by the rays traveling toward the central portions of the first area A1 to the third area A3 are θ ₁ , θ ₂ (rad) (where these angles θ ₁ , θ ₂ are 1 (rad) Is sufficiently smaller than the first light source 2A and the third light source 2C.
The portions where and are to be mounted are in a state of being inclined by θ ₁ and θ _{2 with} respect to the second light source 2B, respectively. Further, the first light source 2A to the third light source 2C are configured such that the lighting operation is repeated one by one under the control of the control unit 5, for example, 2-3 times (several times) per second. Thus, the raster scanning is automatically and instantaneously performed on all the barcodes and the information is accurately read.

One photodiode is used for the light receiving element 3, and the multi-stage bar code symbol 4 emitted from each light source is divided into three areas, that is, a first area A1 to a third area A.
Each of the reflected lights reflected by 3 is transmitted through the condenser lens 31 and then sequentially incident with a temporal shift. The light receiving element 3 outputs a signal corresponding to the bar code 40 at each stage when these reflected lights are incident. In this embodiment, the light-receiving element 3 is composed of one photodiode, but it is not limited to this, and the same number of light sources may be used. The light receiving element is not particularly limited to the photodiode, and may be, for example, a CCD (charge coupled device). Further, in this embodiment, the multi-stage bar code 40
In addition to the normal information, unique identification information is recorded so that the read signal can be easily identified from which bar code 40 of the read signal.

The multi-stage bar code symbol 4 of this embodiment uses a 16-stage bar code 40 so that the information described therein can be read easily and accurately.

As shown in FIG. 4, the control unit 5 is configured to perform control such that the on / off operations of the semiconductor lasers, which are the first light source 2A to the third light source 2C, are periodically repeated. There is.

Therefore, according to this embodiment, it is possible to surely and quickly read the 16-step bar code 40 without leaking even one step.

[0016]

As described above, according to the present invention, a plurality of light sources are installed in a specific direction, and the light emitted from these light sources is sequentially applied to the respective divided areas of the bar code symbol. The light is projected at different times,
As a result, the scanning can be reliably read without increasing the number of reflecting surfaces of the scanning mirror, so that the manufacturing cost can be reduced and the apparatus can be easily downsized. Moreover, according to the present invention, the distance between the scanning mirror and the bar code and the inclination angle difference between the adjacent reflecting surfaces of the scanning mirror are set to have a constant relationship, whereby the scanning mirror for raster scanning Since the tilt of the rotation axis can be reduced, the light reflected by the scanning mirror can be projected and scanned in a substantially linear shape instead of a large arc shape with respect to the bar code, and it does not deviate from the bar code. An accurate raster scanning operation can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a barcode symbol reader according to the present invention.

FIG. 2 is an explanatory view showing a gap between a tilt angle difference between adjacent reflecting surfaces of the scanning mirror according to the present invention and a barcode gap of each stage.

FIG. 3 is an explanatory diagram showing a relationship between each light source and a barcode symbol according to the present invention.

FIG. 4 is a block diagram showing the electrical connection of a barcode symbol reader according to the present invention.

[Explanation of symbols]

 1 Scanning mirror (Polygon mirror) 2 Light source 3 Light receiving element 4 Multi-stage bar code symbol

Claims (1)

[Claims] 1. A signal emitted from a light source and reflected by a scanning mirror is projected toward a multi-stage bar code symbol, and the light reflected by the bar code symbol is received by a light receiving unit and output from the light receiving unit. Is a bar code symbol reading device for reading information described in the bar code symbol, wherein the rotation axis of the scanning mirror is provided offset from the central axis, and the light source is composed of a plurality of sources and installed therein. The direction is changed to a predetermined angle, the light from each light source is projected to different areas of the barcode symbol, the lighting operation of the light source is repeated one by one, and the multi-stage barcode symbol from the plurality of light sources is emitted. A bar code symbol reader characterized by being configured to read with light.