JPH0765100A - Bar code reading method and device - Google Patents

Abstract

(57) [Abstract] [Purpose] To make it possible to read a barcode formed on the surface of a mirror-like body on a glass substrate with a reflection-type barcode reader that could not be used conventionally. [Structure] A white reflective diffusion plate 15 is attached to a part of the inner surface of the hood 2 near the lower opening, and a bar code reader 4 is attached to the upper part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a bar code reading method and apparatus, and more particularly in the field of manufacturing semiconductor devices and liquid crystal display panels, and a method and apparatus for reading a bar code formed on a mirror surface of a glass substrate or the like. Regarding

[0002]

2. Description of the Related Art Automatic recognition of products using bar codes is widely used in the secondary market because it is cheaper and easier to handle than optical character recognition devices. However, a glass substrate related to a liquid crystal display panel or a thin film formed on the surface of the glass substrate is a mirror surface, and a bar code formed by etching or laser marking is difficult to distinguish between a bar and a space. No commercial bar code reader was available.

Conventionally, in this field, a special bar code reader in which a light projecting portion and a light receiving portion of a system of reading by a light transmitted through a bar code portion formed on a transparent substrate such as glass are separated is slightly used. Also, as another method, CCD
Reading a barcode pattern captured by a camera by a computer image recognition method is also slightly used.

[0004]

A bar code is usually formed by printing a black bar on a white background, but it cannot be used on a glass substrate for manufacturing a liquid crystal display panel because it dislikes dust. As a specific method of forming a bar code, a metal thin film on a glass substrate is marked by melting and blowing off the surface with a laser beam or marking is performed, or a bar code pattern is exposed to a photosensitive resist applied on the surface, and after development, It is formed by etching. In any case, the barcode is formed on the surface in a mirror state.

As shown in FIG. 4, when the bar code 18 printed on a blank sheet is read by the laser scanning type bar code reader 4, the irradiation light 19 from the light emitting section 5 is absorbed by the black bar sections 22 (plural). The white bar portions 23 (plurality) are reflected like the reflected diffused light 20, and a part of the reflected diffused light 21 reaches the light receiving portion 6. As a result, the light receiving unit output as shown in FIG.
Can be recognized as a high level and the black bar portion 22 can be recognized as a low level.
The barcode 18 can be read.

However, as shown in FIG. 6, in the case of the bar code 25 formed on the glass substrate 7, the pattern is recessed with respect to the periphery by scraping the metal thin film 8 on the surface of the glass substrate 7. Only.

Therefore, the irradiation light 19 from the light emitting section 5 of the bar code reader 4 becomes almost regular reflection light 24 at any portion and does not return to the light receiving section 6 of the bar code reader 4.
As a result, only the light receiving unit output as shown in FIG. 7 is obtained, and the barcode 25 cannot be read. This is the same even if the barcode pattern 25 is inverted in black and white.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a bar code reading method and apparatus which can correctly recognize even a bar code formed on the surface of a specular body with a simple structure. is there.

[0009]

In order to achieve the above object, the present invention irradiates a bar code provided on an object with irradiation light from a light emitting portion from a direction inclined with respect to the surface of the object. In a barcode reading method of reading the barcode by receiving the reflected light reflected by the object with a light receiving unit provided integrally with the light emitting unit, the reflected light progresses in the vicinity of the barcode. A reflection surface is provided in the direction, and the reflection light is reflected by the reflection surface so that the reflection light is received by the light receiving unit.

In such a method, the reflected light may be diffusely reflected by the reflecting surface, or may be specularly reflected by the reflecting surface and then transmitted through an auxiliary plate to be diffused. Or may be such that it is specularly reflected by the reflecting surface and then passes through a filter and is attenuated.

Further, according to the present invention, the light emitted from the light emitting unit is applied to the bar code provided on the object in a direction inclined with respect to the surface of the object, and the reflected light reflected by the object is emitted. In a bar code reading device for reading the bar code by receiving light by a light receiving section provided integrally with the light receiving section, a reflection surface is provided inside an outside light blocking hood integrated with the light emitting section and the light receiving section. By reflecting the reflected light from the object on the reflecting surface, the reflected light is received by the light receiving section. At this time, the reflecting surface may diffusely reflect the reflected light.

[0012]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

As shown in FIG. 3, the bar code 25 (see FIG. 6) formed on the metal thin film (mirror surface) 8 on the glass substrate 7 has a portion (metal thin film) corresponding to a white background portion of the bar code 25. Light from the front surface 8) to the bar code reader 4 is returned to the light receiving unit 6 as an appropriate amount of return light 16 (a part of diffused light of the specular reflection light 14), and return light 17 from the black bar unit 9 is generated. If there is a clear level difference with (a part of diffused light of specular reflection light 13), it can be read. Therefore, in this embodiment, as shown in FIG.
As shown in, the surface is a matte white reflective diffuser 1
5 is placed in the vicinity of the bar code part and along the traveling direction of the reflected light 14 reflected by the metal thin film 8, and the light 14 specularly reflected by the bar code part is diffusely reflected and returned to the light receiving part 6. .

When the bar code 25 without the black bar portion 9 is formed on the metal thin film 8 on the glass substrate 7 shown in FIG.
As shown in FIG. 3, the specular reflection light 14 from the metal thin film 8 corresponding to the white background is strong, and most of the irradiation light from the light emitting portion 5 in the black bar removal portion 9 becomes the transmission light 12 that passes through the glass substrate 7. Therefore, the specular reflection light 13 from the black bar removal portion 9 becomes weak. Further, the specular reflection lights 13 and 14 are diffused and reflected by the diffuse reflection plate 15, and are weak diffused lights (returned lights 16 and 1).
7), and a part of the diffused light (returns 16 and 17) reaches the light receiving unit 6.

In this embodiment, since the return light 16 becomes larger than the return light 17 at this time, as a result, the light receiving section 6 obtains the bar code 18 (see FIG. 4) printed on a blank sheet of paper. The output similar to that shown in FIG. 5 is obtained, and the barcode 25 can be read.

An embodiment of the present invention using the reflective diffusion plate 15 is shown in more detail in FIG. A hood 2 that blocks external light is attached to a barcode reader 4 in which a light emitting unit 5 and a light receiving unit 6 are integrated. The inner wall of the hood 2 has a black matte surface to prevent the scattering of extra light. The lower opening of the hood 2 faces the bar code 25 on the substrate 7, and a reflective diffusion plate 15 such as white ceramic or frosted glass is attached to a part of the inner surface of the lower opening of the hood 2.

The light emitting portion 5 of the bar code reader 4 to the substrate 7
The irradiation light emitted from the direction inclined with respect to the surface of the (metal thin film 8) almost passes through the glass surface 7 in the black bar removal portion 9 (see FIG. 3) of the barcode 25 and corresponds to the white background of the barcode 25. The metal thin film 8 is almost regularly reflected. The specularly reflected light is diffused by the reflection / diffusion plate 15 and then reaches a part of the light receiving unit 6.

In this embodiment, when the surface 3 of the hood 2 on which the reflection / diffusion plate 15 is attached is made substantially vertical to the glass substrate 7, the reflection efficiency to the light receiving portion 6 is maximized and the reading accuracy is improved. It is set to be high.

Next, another embodiment of the present invention using a transmission diffusion plate or an attenuation filter is shown in FIG. In this embodiment, the light receiving section 6 receives the reflected light via a ground glass that transmits and diffuses light or a filter 11 such as an ND filter that transmits and attenuates light. Barcode 2
The specularly reflected light on the surface of the metal thin film 8 of No. 5 is the reflection diffusion plate 1
It is specularly reflected again by the mirror 10 provided in place of 5,
It reaches the filter 11. The light attenuated by the filter 11 enters the light receiving unit 6.

[0020]

The present invention has a simple structure as described above, but according to the present invention, conventionally, the irradiation light is not specularly reflected by the bar code surface and does not return to the light receiving portion, so that it can be used. A general commercial bar code reader which has not been used can also be used for reading a bar code formed on the surface of a mirror body. Further, according to the present invention, a simple hood-like member may be attached, and the hood itself is small and can be manufactured at a very low cost.

The reflection type bar code reader can be read to some extent by placing a reflection diffusion plate on the lower surface of the glass plate, but when a color filter material is applied,
The irradiation light of the barcode scanner and the filter material of the complementary color system absorb the light, and as a result, the glass plate cannot be read from the upper surface or the lower surface.

This is because the reflection of transmitted light is utilized. The same can be said for the bar code reader of the light emitting / light receiving separating type because the transmitted light is used. However, in the case of the present invention, since it is not necessary to utilize transmitted light,
It is possible to stably read from the lower surface where the filter material is not applied regardless of the presence or absence of the filter material.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a cross-sectional view of a bar code reader using a reflective diffusion plate.

FIG. 2 shows another embodiment of the present invention and is a cross-sectional view of a bar code reader using a filter.

FIG. 3 is a diagram showing the principle of the present invention for reading a barcode by using a reflective diffusion plate.

FIG. 4 is a diagram showing an example of reading a barcode printed on a blank sheet.

5 is a diagram showing an output waveform of the barcode reader light receiving unit in the example of FIG. 4;

FIG. 6 is a diagram illustrating a case of reading a barcode on a glass substrate.

FIG. 7 is a diagram showing an example of an output waveform of the light receiving unit in the case of FIG.

[Explanation of symbols]

 2 Hood 4 Bar code reader 5 Light emitting part 6 Light receiving part 7 Glass substrate 8 Metal thin film 11 Filter 15 Reflective diffuser plate 25 Bar code 21 Partial reflected diffused light

Claims (6)

[Claims] 1. A bar code provided on an object is irradiated with light emitted from the light emitting unit from a direction inclined with respect to the surface of the object, and reflected light reflected by the object is integrated with the light emitting unit. In the bar code reading method of reading the bar code by receiving light by a light receiving unit provided in, a reflection surface is provided in a direction in which the reflected light proceeds in the vicinity of the bar code, and the reflection surface reflects from the object. A bar code reading method, wherein the reflected light is received by the light receiving section by reflecting light. 2. The bar code reading method according to claim 1, wherein the reflected light is diffused and reflected by the reflecting surface. 3. The bar code reading method according to claim 1, wherein the reflected light is specularly reflected by the reflecting surface and then transmitted through an auxiliary plate to be diffused. 4. The bar code reading method according to claim 1, wherein the reflected light is specularly reflected by the reflecting surface and then passes through a filter to be attenuated. 5. A bar code provided on an object is irradiated with light emitted from the light emitting unit from a direction inclined with respect to the surface of the object, and reflected light reflected by the object is integrated with the light emitting unit. In a bar code reading device for reading the bar code by receiving light by a light receiving section provided in the light receiving section, a reflecting surface is provided inside an outside light blocking hood integrated with the light emitting section and the light receiving section, and the reflecting surface is provided. A bar code reading device, characterized in that the reflected light from the object is reflected by the light receiving section to receive the reflected light. 6. The bar code reader according to claim 5, wherein the reflection surface diffuses and reflects the reflected light.