JP2003108916A - Barcode reading method and barcode reader - Google Patents

Abstract

(57) [Problem] To provide a barcode reading method and a barcode reading device capable of suppressing erroneous reading of a barcode displayed by a display device that displays an image in a pixel configuration on a screen. . According to the present invention, a light guide plate is provided on the front of a screen of a display device that displays an image in a pixel configuration on a screen. It has an illumination light source that illuminates a wider area than the illumination area, and the illumination angle of the illumination light source is larger than the total reflection angle of the light guide plate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reading method and a bar code reading apparatus, and more specifically, to a PH.
A barcode that can prevent erroneous reading of a barcode displayed on a liquid crystal display device of a portable electronic device such as an S, a mobile phone (mobile communication device) such as a mobile phone, an electronic book, or a PDA. The present invention relates to a reading method and a bar code reading device.

[0002]

2. Description of the Related Art Conventionally, a system has been proposed in which a barcode is displayed on a liquid crystal display device and the barcode is read by a reading device, and recently, a portable type having a liquid crystal display device such as a PHS or a mobile phone. A system has been proposed in which a bar code is displayed on a mobile phone and the bar code is read to receive a certain discount service. In such a system, a bar code encrypted with discount service information or the like transmitted from the system provider is received by a PHS, a mobile phone, or the like, and when the user purchases a particular product at a store, the bar code is received. Is displayed on the display device of the telephone and the displayed contents are presented to the clerk. By reading the barcode with a device such as a POS, the store clerk receives a specific discount service at the time of payment.

Such a system has been proposed for some time and has been partially put into practical use. However, in order to make it easier to read a bar code in front of a liquid crystal screen, it is transparent and has polarization characteristics for light from the liquid crystal. Plate (light guide plate) is provided. Therefore, the bar code displayed on the liquid crystal screen is read via this light guide plate. On the other hand, POS
The reading device side such as has a light emitting element and a light receiving element for reading a bar code, and the light receiving element receives a change in the intensity of the reflected light from the reflecting surface of the liquid crystal display device and converts it into an electric signal. Get information from barcodes.

[0004]

However, in order to read the bar code from the screen of the liquid crystal display device, the light from the light emitting element is partially reflected by the light guide plate, and the light receiving element is in front of receiving the bar code information. The reflected light affects the reflected light from the barcode. As a result, there is a problem that the reading device cannot read the barcode properly depending on the display state or the liquid crystal display model. However, if the light guide plate is eliminated, the amount of diffused reflection light from the liquid crystal screen will increase, and the white level of the liquid crystal screen will fall below that of paper, making it more difficult to read the barcode. An object of the present invention is to solve the above-mentioned problems of the prior art and to prevent erroneous reading of a bar code displayed by a display device that displays an image with a pixel configuration on a screen. It is to provide a reading method and a bar code reading device.

[0005]

The features of the barcode reading method and the barcode reading device of the present invention for achieving the above-mentioned object are that a front face of a screen of a display device for displaying an image with a pixel configuration on the screen is provided. The light guide plate is provided and has an illumination light source for illuminating white irradiation light including a wavelength with high light receiving sensitivity in the barcode reading device in a range wider than the irradiation area of the laser light, and the irradiation angle of this illumination light source is the light guide plate. Is larger than the total reflection angle of.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, white illumination light including a wavelength having a high light receiving sensitivity in a bar code reader at an angle larger than the total reflection angle of the light guide plate and larger than the laser light irradiation area. Since the bar code on the screen is irradiated, even if the reflected light from the surface of the light guide plate due to the irradiation of the laser light is mixed, the reflected light from the bar code is added by the irradiation light from the illumination light source. Enhanced reflected light can be obtained corresponding to the bar code stripes. At this time, since the irradiation angle of the illumination light source is larger than the total reflection angle of the light guide plate, the reflected light is enhanced corresponding to the reflected light corresponding to the stripe of the barcode, and the reflected light at the light receiving level is increased. The S / N ratio is improved, and the reduction of the contrast of the reflected light of the barcode due to the reflected light from the light guide plate is suppressed. As a result, it is possible to prevent erroneous reading of the barcode displayed on the display device that displays an image with a pixel configuration on the screen.

[0007]

1 is a schematic view of an embodiment of a bar code reading method to which the present invention is applied, and FIG. 2 shows a bar code reading device of the embodiment shown in FIG. FIG. 3 is an explanatory view of an optical path for reading a code, FIG. 3 is a graph illustrating the correlation between the illuminance of the screen and the reading rate of the liquid crystal display device in the embodiment of FIG. 1, and FIG. 4 is a bar code reading device to which the present invention is applied. FIG. 5 is an explanatory diagram of an embodiment of the present invention, and FIG. 5 is an explanatory diagram of an optical path through which a conventional barcode reading device reads a barcode displayed on a liquid crystal display device. Figure 1
In the figure, 1 is a mobile phone, 2 is a screen of the liquid crystal display device, 3 is a light guide plate having polarization characteristics, and 4 is a bar code displayed on the screen. Reference numeral 5 is a bar code scanner (reading device) connected to a POS or the like for reading the bar code displayed on the mobile phone 1, 6, 6
Is a light emitting element provided on both sides of the line sensor (light receiving element), 7 is a CCD line sensor (hereinafter referred to as line sensor), and 8 is an auxiliary light source. The skin control circuit and the like of the bar code scanner 5 are omitted in the figure. P
The light emitting element 6 of the barcode scanner 5 such as OS is usually
It is composed of a red laser diode and emits red light.
Therefore, the line sensor 7 uses an element having high sensitivity to the red wavelength.

Here, the auxiliary light source 8 for illuminating the screen 2 is
It is a fluorescent lamp with a light bulb color. Light bulb color fluorescent tubes are so-called 3
It is a light source that uses a wavelength phosphor and has a peak in the red wavelength, and that is a light source that irradiates a barcode with a larger irradiation area than that of a point or line irradiation range such as laser light. . The irradiation light is applied to the screen 2 from a direction different from the irradiation direction of the light emitting element 6, and is not the focused irradiation light having a strong directivity like the laser light. In this embodiment, the irradiation optical axis of the auxiliary light source 8 is set to an angle lower than the irradiation optical axis of the light emitting element 6 by 10 ° or more. However, when this is irradiated at a low angle, it is totally reflected on the surface of the light guide plate 3, so that erroneous reading occurs. The irradiation angle of the auxiliary light source 8 needs to be larger than this total reflection angle (≈45 °). Since the auxiliary light source 8 is not a laser beam, its reflected light is obtained from a wide irradiation direction.
Is reflected from the line sensor 7 side. The irradiation angle is appropriately selected in the range of about 50 ° to 60 ° according to the polarization characteristics of the light guide plate 3.

The laser light from the light emitting element 6 is received at a specific angle (60 ° -80 °) so that it is received by the line sensor 7 side.
The bar code is irradiated with a degree. Since the barcode 4 normally has a striped pattern in which white and black are repeated, the reflected light of the laser light irradiated in a specific direction has a relationship as shown in FIG. Mix with reflected light to reduce contrast. In FIG. 5, 10 is the irradiation laser beam from the light emitting element 6, and 11 is the light guide plate 3 thereof.
The reflected light from the surface of the bar code 12 is the reflected light from the bar code surface on which white and black liquid crystals are formed. The reflected light 11 from the surface of the light guide plate 3 and the reflected light 12 from the barcode surface match the direction of the line sensor 7. Moreover, the reflected light (indicated by a dotted line) where the reflected light 11 deviates by the thickness difference t between the barcode surface and the surface of the light guide plate 3 is superimposed on the reflected light overlapping the stripe portion of the barcode. . Since the difference t at this time is as thin as several meters in the liquid crystal display device, the light guide plate 3
The reflected light 11 from the surface of the bar code is superimposed on the reflected light from the other bar code on the bar code surface to dilute the white and black striped state, and the original contrast of the striped state is lowered.

On the other hand, the light from the auxiliary light source 8 is not directed light as directional as the laser light, but is directed from a direction different from the irradiation direction of the light emitting element 6, so that the bar code surface is irradiated. In this case, the reflected light from the other direction is larger than the superposed reflected light, and the reflected light corresponding to the stripe of the barcode is enhanced. This will be described with reference to FIG. In FIG. 2, 13 is one of the irradiation lights from the auxiliary light source 8, and 14 is a reflected light from the barcode surface by the irradiation light 13. Irradiation light 13 from the auxiliary light source 8
In the above, the irradiation direction is different from that of the light emitting element 6, and more light is emitted from the direction different from the direction from the adjacent stripe of the barcode. This enhances the reflected light corresponding to the bar code stripes. Moreover, of the reflected light from the surface of the light guide plate 3 generated by the irradiation light from the auxiliary light source 8, the level of the light in the direction corresponding to the direction from the stripe of the adjacent barcode is low. As a result, the reduction in the contrast of the reflected light of the barcode is suppressed, and the barcode displayed on the liquid crystal surface can be read accurately.

FIG. 3 is an average characteristic graph obtained by measuring the illuminance on the liquid crystal surface and the reading rate when the angle is set to be lower by about 15 ° with respect to the irradiation optical axis of the light emitting element 6. In FIG. 3, the vertical axis represents the reading rate and the horizontal axis represents the illuminance. Illumination A indicated by ♦ is a fluorescent lamp of a light bulb color, and illumination B indicated by □ is a white fluorescent tube. As shown by these characteristics, the illuminance is from 10000 lux to 140 lux.
High reading rate in the range of 00 lux. Illuminance is 1400
When it exceeds 0 lux, the reading rate decreases because the reflected light that is added by the auxiliary light source 8 and increases increases.
It is presumed that the contrast is lowered due to saturation on the side.

FIG. 4 shows an embodiment of a bar code reading apparatus in which an auxiliary light source 8a is incorporated in the central portion of the upper surface of the bar code scanner 5 and is enlarged and converged by a lens 9 provided in the front light projecting section. And the screen 2 is illuminated. The other configuration is similar to that of FIG. 1, and therefore its description is omitted.
Of course, the optical axis of the auxiliary light source 8a is set by the lens 9 and is set at an angle lower than the laser irradiation direction of the light emitting element 6. A xenon lamp is used as the light source lamp.

As described above, in the embodiment, a bar code scanner is used as the bar code reading device, but the bar code scanner is not limited to the scanner type. Further, the scanner type light emitting element side may be a type in which a point light source is shaken instead of the element array. Further, it is needless to say that the scanner type light receiving element side is not limited to a one-dimensional CCD linear sensor, and a two-dimensional sensor such as an image sensor may be used. In addition,
In the example, a light bulb color light source and a white light source are mentioned,
In the sense of including these light sources, including wavelengths with high photosensitivity,
In addition, it is of course possible to use a light source of irradiation light that includes a wavelength component of another color and becomes white as a whole. Further, the light source is not limited to the fluorescent tube. In the above-mentioned embodiment, the example of the liquid crystal display device is given, but it goes without saying that the present invention can be applied to an organic EL display device which displays a bar code by a pixel configuration.

[0014]

As described above, according to the present invention, the light receiving sensitivity of the bar code reading device is high at an angle larger than the total reflection angle of the light guide plate and larger than the laser light irradiation area. Since the bar code on the screen is illuminated with the white illumination light including the wavelength, even if the reflected light from the surface of the light guide plate due to the irradiation of the laser light is mixed, the irradiation light from the illumination light source can be added. As reflected light from the barcode, enhanced reflected light corresponding to the stripes of the barcode can be obtained. As a result, it is possible to prevent erroneous reading of the barcode displayed on the display device that displays an image with a pixel configuration on the screen.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a barcode reading method to which the present invention is applied.

FIG. 2 is an explanatory diagram of an optical path by which the barcode reading device in the embodiment of FIG. 1 reads a barcode displayed on a liquid crystal display device.

FIG. 3 is a graph illustrating the correlation between the screen illuminance and the reading rate of the liquid crystal display device in the embodiment of FIG.

FIG. 4 is an explanatory diagram of an embodiment of a bar code reading device to which the present invention is applied.

FIG. 5 is an explanatory diagram of an optical path in which a conventional barcode reading device reads a barcode displayed on a liquid crystal display device.

[Explanation of symbols]

1 ... mobile phone, 2 ... screen of liquid crystal display device, 3 ... light guide plate,
4 ... Bar code displayed on the screen, 5 ... Bar code scanner, 6 ... Light emitting element, 7 ... Line sensor, 8, 8a ... Auxiliary light source, 10 ... Laser light emitted from light emitting element 6, 11 light guide plate 3 Light reflected from the surface of the bar code, 12 ... reflected light from the bar code surface, 13 ... irradiation light from the auxiliary light source 8, 14 ... reflected light from the bar code surface of the auxiliary light source 8.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Chika Suzuki             Hitachima, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. (72) Inventor Ichiro Fujita             Hitachima, 1-88, Torora, Ibaraki City, Osaka Prefecture             Within Kucsel Co., Ltd. F-term (reference) 5B072 AA02 CC24 LL11 MM11

Claims (3)

[Claims] 1. A bar code reading method for reading a bar code displayed by a display device for displaying an image with a pixel configuration on a screen by irradiating a laser beam with a bar code reading device. The light source has an optical plate and an illumination light source that illuminates white-based irradiation light including a wavelength having high light-receiving sensitivity in the barcode reading device in a range wider than the irradiation region of the laser light. A barcode reading method characterized in that it is larger than the total reflection angle of the light plate. 2. The display device is a liquid crystal display device, the laser light is red light, and the illumination light source is a fluorescent tube whose illuminance on the surface of the light guide plate is in the range of 10,000 to 14,000 lux. The barcode reading method according to claim 1. 3. A bar code reading device which irradiates a laser beam to read a bar code displayed on a display device which has a light guide plate on the front surface of the screen and displays an image in a pixel configuration on the screen. The apparatus has an illumination light source that illuminates white-based irradiation light including a wavelength with high light-receiving sensitivity in a range wider than the irradiation area of the laser light, and the irradiation angle of the illumination light source is larger than the total reflection angle of the light guide plate. A bar code reading device characterized by the above.