JPH04276877A - Bar code detector - Google Patents

Abstract

PURPOSE:To miniaturize a multilead type bar code detector and to reduce the power consumption thereof by using a semiconductor laser for the laser light source. CONSTITUTION:This bar code detector is equipped with a semiconductor laser 1 as a laser light source, a collimate lens 2 that converges laser light and that generates a laser beam 4, a polygon mirror 5 for scanning the laser beam 4, and a reflective mirror group 6 that can read generates more than 5 directional laser beam scanning lines by making the scanned laser beam 4 reflect so as to be able to read even the laser beam 4 emitted from the semiconductor laser 1 and having a large aspect ratio, and a PIN diode 9 that receives a reflected light from bar code 7 by laser beam scanning line.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a barcode detection device used in POS systems, logistics management, production management, etc.

0002

2. Description of the Related Art A conventional barcode detection device configured to scan a laser beam in multiple directions (multi-read barcode detection device) uses a helium neon laser tube as a laser light source. The shape of the laser beam was circular. Further, the directions of the scanning lines of the laser beam were set to three directions as shown in FIG.

0003

[Problem to be Solved by the Invention] By the way, if the scanning lines of the laser beam are in three directions, in order to detect barcodes facing in all directions, it is necessary to calculate the angle at which the scanning lines cross the barcode. If the rotation angle is θ (see Figure 5),
It is necessary to be able to detect a barcode within a range of rotation angle θ of ±30 degrees using a scanning line in one direction.

However, as shown in FIG. 6, when the shape of the laser beam is such that the beam diameter Y in the direction perpendicular to the scanning direction is longer than the beam diameter X in the direction parallel to the scanning direction, As shown in (a), barcodes can be detected with high accuracy when the rotation angle is small, but as shown in (b), when the rotation angle becomes large, the laser beam also irradiates adjacent bars (or spaces). Therefore, there is a problem that the resolution deteriorates and it becomes impossible to detect barcodes with high accuracy.

The results of actually changing the aspect ratio (the ratio of the beam diameter in the long axis (vertical) direction to the beam diameter in the short axis (horizontal) direction) of the laser beam and measuring the readable rotation angle θ at that time are shown below. Shown in FIG. From FIG. 8, in order to be able to read at a rotation angle θ of 30 degrees, the aspect ratio of the laser beam must be 1.
It turns out that it needs to be 8 or less.

However, when a laser beam is formed by condensing the light of a semiconductor laser, the shape of the laser beam becomes an ellipse with an aspect ratio of 2.5 to 5.0. Therefore, a semiconductor laser cannot be used as a laser light source in the conventional multi-read type barcode detection device, making it difficult to downsize and reduce power consumption.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a multi-read type barcode detection device that uses a semiconductor laser as a laser light source to achieve miniaturization and low power consumption.

[0008]

[Means for Solving the Problems] The barcode detection device of the present invention includes a laser light source, a condensing means for condensing laser light from the laser light source to generate a laser beam, and a condenser for scanning the laser beam. The scanning device includes a scanning device, a reflecting device that reflects the scanned laser beam in a plurality of directions to generate laser beam scanning lines in a plurality of directions, and a light receiving device that receives reflected light from the barcode of the laser beam scanning line. In the barcode detection device according to the present invention, the reflecting means is configured so that the direction of the laser beam scanning line is divided into five or more directions divided at approximately equal angles, and the laser light source is comprised of a semiconductor laser.

[0009]

[Function] According to the barcode detection device of the present invention, the scanning line direction is set to five or more directions, so that the scanning line in one direction is ±
It is only necessary to be able to read up to a rotation angle of 18 degrees, and it is also possible to read the laser beam shape when using a semiconductor laser as the laser light source, so it is possible to use a semiconductor laser as the laser light source to reduce size and power consumption. A multi-lead type barcode detection device can be realized.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A barcode detection apparatus according to an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, a laser beam emitted from a semiconductor laser (TOLD9210: manufactured by Toshiba) 1 that emits a laser beam with a wavelength of 675 nm is condensed by a collimating lens 2 with a focal length of 7.0 mm, and is further focused by a collimating lens 2 with a length of 3 mm and a width of 3 mm. It is shaped with a 1 mm slit 3 to form an elliptical or oval laser beam 4 with an aspect ratio of 3.0. The laser beam 4 is incident on the polygon mirror 5 such that the rotation direction of the polygon mirror 5, which has four reflecting surfaces and rotates at a rotation speed of 6000 rpm, coincides with the short axis direction of the laser beam 4, and as a result, the laser beam The beam 4 is scanned over a range of about 180 degrees in the same direction as its short axis.

The scanned laser beam 4 is arranged so that it circumscribes a circle with a radius of 40 mm centered at the position where the laser beam 4 is reflected by the polygon mirror 5, and makes an angle of 144 degrees with an adjacent mirror. 2 and is reflected by a group of five reflective mirrors 6 tilted toward one side in the axial direction of the polygon mirror 5.
As shown in the figure, scanning is performed in five directions divided into approximately equal angles of about 36 degrees.

Further, the scanning direction is the same direction as the short axis direction of the elliptical or elliptical shape of the laser beam 4.

The laser beam 4 scanned in five directions scans the barcode 7, and the reflected light from the barcode 7 is condensed by a condensing lens 8 with a diameter of 30 mm, and a PIN photodiode (S1223-01: Hamamatsu) manufactured by Photonics)
The image is formed on 9. This PIN photodiode 9 converts the light reception signal into an electrical signal and outputs it, and the barcode 7 is read.

As described above, since the barcode 7 is scanned by the laser beam 4 from five directions, no matter how the barcode 7 is positioned at the reading position, any one of the scanning lines of the laser beam 4 will be scanned. is scanned at a rotation angle θ of ±18 degrees or less with respect to the barcode 7, and the laser beam 4
Even if the shape is elliptical or oblong, it can be read properly. Note that the output signal of the PIN photodiode 9 is output during scanning in each direction, and the signal with the best resolution is selected from the output signals to read the barcode 7.

In the above embodiment, all four reflecting surfaces of the polygon mirror 5 are formed parallel to the rotation axis or inclined at the same angle, and when the polygon mirror 5 rotates once, the laser beam 4 moves in five directions. 4 on the same scanning line
However, if the angle of each of the four reflective surfaces of the polygon mirror 5 with respect to the rotation axis is changed by several degrees, the scanning line of each reflective surface will sequentially move in parallel at the reading position of the barcode 7. Four parallel scanning lines can be created for each of the five scanning directions, and a maximum of 20 scanning lines can be created. FIG. 3 shows the scanning state of the scanning lines when there are 20 scanning lines.

[0017] By forming a plurality of parallel scanning lines in each direction in this way, a wide range can be read with high precision, and the readable area of the barcode 7 can be expanded.

According to the above embodiment, the semiconductor laser 1
By using this, the volume ratio is reduced to 1/5 compared to the conventional method. Also, in the past, the power consumption was 800mA/5V, so the power could not be taken directly from a computer such as a POS, and a separate power supply was required, but in this example, the power consumption is 300mA/5V. , POS, etc. can be powered directly from a computer, eliminating the need for a separate power supply.

[0019]

[Effects of the Invention] According to the barcode detection device of the present invention,
By setting the scanning line direction to five or more directions, it is possible to read the laser beam shape even when a semiconductor laser is used as the laser light source, and by using a semiconductor laser as the laser light source, the multi-read barcode detection device can be miniaturized. Lower power consumption can be achieved.

Furthermore, by forming a plurality of parallel scanning lines in each direction, a wide range can be read with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a barcode detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a scanning state of a laser beam in the same embodiment.

FIG. 3 is a diagram showing a scanning state of a laser beam in another embodiment.

FIG. 4 is a diagram showing a scanning state of a laser beam in a conventional barcode detection device.

FIG. 5 is a diagram showing the definition of rotation angle.

FIG. 6 is a diagram showing the shape of a laser beam.

FIG. 7 is an explanatory diagram for explaining problems in the conventional example.

FIG. 8 is a diagram showing the relationship between the aspect ratio of a laser beam and the readable rotation angle.

[Explanation of symbols]

1 Semiconductor laser 2 Collimating lens 4 Laser beam 5 Polygon mirror 6 Reflection mirror group 7 Barcode 9 PIN photodiode

Claims (3)

[Claims] Claim 1: A laser light source, a focusing means for collecting laser light from the laser light source to generate a laser beam, a scanning means for scanning the laser beam, and a scanning means for scanning the laser beam in a plurality of directions. In a barcode detection device, the barcode detection device is equipped with a reflecting means for generating laser beam scanning lines in a plurality of directions by reflecting the laser beam from the barcode, and a light receiving means for receiving the reflected light of the laser beam scanning line from the barcode. 1. A barcode detection device, characterized in that the reflection means is configured so that the reflection means is divided into five or more directions divided at substantially equal angles, and the laser light source is comprised of a semiconductor laser. 2. The barcode detection device according to claim 1, wherein the shape of the laser beam is an ellipse or an oval whose short axis direction substantially coincides with the scanning direction in the reading range. 3. The barcode detection device according to claim 1, wherein each of the laser beam scanning lines in five or more directions includes a plurality of parallel laser beam scanning lines.