JPH03175589A - Bar code reader - Google Patents

Abstract

PURPOSE:To enlarge a mirror for photodetection, to eliminate the necessity of a motor to oscillate the mirror and to suppress trouble such as the fault of a driving mechanism, etc., by freely oscillating a mirror for projection and fixing the mirror for photodetection. CONSTITUTION:A laser beam 2 from a laser oscillating source 1 is reflected by a mirror 3 for projection, passed through a through hole 7 of a mirror 6 for photodetection, reaches the surface of a bar code 5, scans the surface, is reflected again on the surface of the bar code 5, becomes scattered light, reaches the mirror 6 for photodetection, is condensed, reflected on this mirror and photodetected by a photodetector 12. In such a case, since the mirror 6 for photodetector is fixed, this mirror can be enlarged and since the motor is not required for oscillating the mirror even when enlarging this mirror, the rouble such as the fault of the driving mechanism, etc., is suppressed. Further, since the injurious laser beam to be full reflected on the surface of the bar code 5 and to return is passed through the through hole 7 and the mirror 6 for photodetection, darkness and brightness for the black and white bars of the bar code are exactly discriminated. Thus, the laser beam is condensed onto the curved mirror without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a barcode reading device, and particularly to a barcode reading device that scans a barcode using a laser beam.

[Conventional technology]

FIG. 5 shows the configuration of a conventional barcode reading device. According to this reading device, a laser beam 32 from a laser oscillation source 31 is reflected by a curved mirror 33, and the laser beam 34 reflected here is irradiated onto the surface of a barcode 35 to scan the barcode 35. . The laser beam that scans this barcode 35 is reflected in various directions on the surface of the barcode 35 and becomes scattered light 36. The laser beam 37 reflected in a predetermined direction is reflected again by the curved mirror 33, and the reflected laser beam 38 is received by a light receiver 39.

The light receiver 39 converts the intensity of the laser beam 37 reflected on the surface of the barcode 35, that is, the intensity depending on the brightness of the black bar and the white bar of the barcode 35, into an electrical signal and outputs the electrical signal.

On the other hand, the curved mirror 33 is oscillated by the motor 40, and the bar code 35 is read based on the oscillation angle and the output level from the light receiver 39 described above.

[Problem to be solved by the invention]

By the way, in order to accurately read the barcode 35 with this type of conventional reading device, it is important to optically correctly distinguish the brightness of the black bar and white bar of the barcode 35. This type of brightness and darkness is determined by the strength of the laser beam 37 received by the light receiver 39, but in order to accurately determine this optically, it is necessary to reliably focus the laser light 37 on the light receiver 39.

In order to reliably focus this light, the curved mirror 33 can be made larger, but this requires the swinging motor 40 to be made larger, which not only leads to an increase in size but also leads to failure of the mirror swinging mechanism. The problem is that it is easy.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a barcode reading device that solves the problems of the above-mentioned conventional techniques and is capable of reliably focusing laser light on a so-called curved mirror.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a swingable light projection mirror that reflects laser light from a laser oscillation source toward a barcode, and a light projection mirror that is disposed in front of the light projection mirror and that reflects a laser beam from a laser oscillation source toward a barcode. A fixed light-receiving mirror that has a through hole that allows the laser light to pass through, and that reflects the laser light that returns after being reflected on the barcode surface again, and a fixed light-receiving mirror that receives the laser light that is reflected by the light-receiving mirror. The device is characterized by comprising a light receiver.

[For production]

According to the present invention, the laser beam from the laser oscillation source is reflected by the light emitting mirror, reaches the surface of the barcode through the through hole of the light receiving mirror, scans there, and returns to the surface of the barcode. It is reflected, becomes scattered light, and reaches the light receiving mirror.
Here, the light is focused, reflected, and received by a light receiver. Since this light-receiving mirror is a fixed type, it can be made large, and even if it is made large, there is no need for a motor to swing the mirror, so troubles such as failure of the drive mechanism are suppressed. In addition, the harmful laser light that is totally reflected and returns on the barcode surface passes through the light receiving mirror through the through hole, so this harmful laser light is reflected by the light receiving mirror and is received by the light receiver. Therefore, the brightness of the black bar and white bar of the barcode can be accurately determined.

〔Example〕

Hereinafter, one embodiment of a barcode reading device according to the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, reference numeral 1 indicates a laser oscillation source.

The laser beam 2 oscillated from here is reflected by a rotatable or swingable light projecting mirror 3 made of a small plane mirror.
The laser beam 4 is irradiated onto the surface of the barcode 5.

A light-receiving mirror 6 made of a large curved mirror is arranged in front of the light-emitting mirror 3, and a rectangular through hole 7 through which the laser beam 4 passes is formed in the center of the light-receiving mirror 6. has been done.

The laser light that is irradiated onto the surface of the barcode 5 and scans the barcode 5 is reflected in various directions on the surface of the bar hood 5 and becomes scattered light 9, of which the laser light 10 that is reflected in a predetermined direction is It is reflected again by the curved surface of the light-receiving mirror 6, becomes a laser beam 11, and is received by a light receiver 12. The light-receiving mirror 6 is of a fixed type, and its curved surface is a three-dimensional paraboloid or the like that can evenly collect the scattered light reflected by the barcode 5.

A light receiver 12 receives laser light 1 reflected on the surface of the barcode 5.
The strength of 0, that is, the strength depending on the brightness and darkness of the black bar and white bar of barcode 5, is converted into an electrical signal and output. on the other hand,
The light projecting mirror 3 is driven to swing in the direction of the arrow by a motor 13. Then, the code of the bar code 5 is read based on the swing angle at which the light projecting mirror 3 swings and the output level from the light receiver 12 described above.

In this type of reading device, as shown in FIG. When light is received, the reflectance of the light becomes high, and both the black bar and the white bar reflect the strong laser light 16. This makes it difficult to distinguish between the brightness and darkness of the black and white bars. At this time, the light receiver 9 is arranged in a direction away from the total reflection angle, that is, in the direction in which the laser beam 18 is reflected.

Further, as shown in FIG. 3, when the laser beam 22 is sent out at right angles from the center of the curved mirror 21, the laser beam 23 that is reflected and returns is totally reflected and returns to exactly the same position. When this laser beam 23 is received by a light receiver (not shown), it becomes difficult to distinguish the brightness of the black bar and the white bar for the same reason as described above.

As is clear from these FIGS. 2 and 3, even if the laser beam returns in the direction of the total reflection angle, it is difficult to distinguish the brightness of the black bar and the white bar of the bar code. According to this embodiment, as shown in FIG. 4, the through hole 7 is formed in the center of the light receiving mirror 6, so that the so-called harmful laser light that returns in the direction of the total reflection angle passes through. Therefore, the harmful laser light is not received by the light receiver, and the brightness of the black bar and the white bar can be accurately determined.

In this embodiment, the light emitting mirror 3 and the light receiving mirror 692
The mirror is divided into two parts. That is, a projection mirror 3 reflects laser beams 2 and 4 from a laser oscillation source 1 toward a barcode 5, and a laser beam 10° 11 that is reflected on the surface of the barcode 5 and returns to a receiver 12. and a light-receiving mirror 6 that reflects the light toward the other direction. As described above, in order to accurately distinguish between the black bar and the dark bar of the barcode 5, it is necessary to reliably focus the reflected laser beams 10 and 11 on the light receiver 12. For this purpose, the light receiving mirror 6 may be made larger.

According to this embodiment, since the light-receiving mirror 6 is of a fixed type, even if the light-receiving mirror 6 is enlarged, problems like the conventional ones do not occur.In other words, even if the light-receiving mirror 6 is enlarged, Since there is no need to swing this, troubles such as breakdowns can be avoided. Further, the projection mirror 3 only needs to reflect the laser beam 2.4 toward the barcode 5. Therefore, this can be made smaller, and as a result, the drive motor 13 can be made smaller.

Although the present invention has been described above based on one embodiment, the present invention is not limited thereto. As another embodiment, the light projection mirror 3 is configured with a so-called surface vibration element such as a magnetostrictive element, an electrostrictive element, or a surface acoustic wave element, and the driving motor 1
3, it is also possible to vibrate the surface of the element to reflect the laser beam 2.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the light-emitting mirror is made swingable and the light-receiving mirror is fixed, so the light-receiving mirror can be made larger. Even if the mirror is made large, a motor for swinging the mirror is not required, so troubles such as failure of the drive mechanism can be suppressed. In addition, the harmful laser light that is totally reflected and returns on the barcode surface passes through the light receiving mirror through the through hole, so this harmful laser light is reflected by the light receiving mirror and is received by the light receiver. Therefore, the brightness of the black bar and white bar of the barcode can be accurately determined.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of a barcode reading device according to the present invention, FIGS. 2 to 4 are explanatory diagrams showing total internal reflection of laser light, and FIG. 5 is a perspective view of a conventional barcode reading device. FIG. 1... Laser oscillation source, 2. 4. 9. 10. 1
DESCRIPTION OF SYMBOLS 1...Laser beam, 3...Mirror for light emission, 6...Mirror for light reception 7...Through hole, 12...Receiver, 13.
··motor.

Claims (1)

[Claims] 1. A swingable light projection mirror that reflects laser light from a laser oscillation source toward the barcode, and a swingable light projection mirror that is placed in front of the light projection mirror to reflect the laser light directed toward the barcode. A fixed light-receiving mirror that has a through hole through which the laser light is reflected and returns again after being reflected on the surface of the bar code, and a light receiver that receives the laser light that is reflected by the light-receiving mirror. A barcode reading device comprising: 2. The barcode reading device according to claim 1, wherein the light projecting mirror is constituted by a surface vibrating element such as a magnetostrictive element, an electrostrictive element, or a surface acoustic wave element.