JPS58112174A - Bar code reader - Google Patents

Abstract

PURPOSE:To increase the reading sensitivity and to prevent the generation of an error for a bar code reader, by illuminating a bar code label through a semicylindrical lens and with use of plural light sources and compressing the reflected light down to about 1/3 and in the lengthwise direction of the bar to feed the compressed light to a photodetecting element. CONSTITUTION:Plural units of light source lamps 6 are arranged in the direction rectangular to a drawing and illuminate with reflection 17 a bar code 8a of a bar code label 8 through a semicylindrical lens 7. This reflected light is formed into an image to a condenser lens 12b of a reading sensor 12 via a flat reflector 9 and via a lens 10 and a slit 11. In this case, a scanning image is formed by compressing the lengthwise direction (rectangular to the paper surface) of the bar code down to about 1/3. Then the sensors 12 are arranged to perform a photoelectric conversion. The scanning image is detected by an electronic control circuit 13. In such a way, the entire surface of the label 8 is used effectively to increase the reading sensitivity as well as to avoid a reading error.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a barcode reading device using a reading sensor that reads barcodes by electronic scanning in a system where barcodes printed on recording media such as labels are distributed together with goods. It is related to.

Conventionally, as shown in FIG. 1, a device that uses a -dimensional image sensor as a reading sensor 1 is known as a device that reads barcodes, that is, light reflected by a coded gray pattern using an electronic scanning type reading sensor. . When using a one-dimensional image sensor used in facsimiles, etc., the light-receiving shape of the photodiode 2 for receiving the light is the length in the longitudinal direction of the barcode scanning image 3 that is imaged on the -dimensional image sensor. The ratio of the length in the direction crossing the longitudinal direction of the bar is approximately 1:1, so the image in the longitudinal direction of the barcode scanning image 3 has the same length as the image in the width direction of the bar. Not only is it not possible to effectively utilize the image in the longitudinal direction of the barcode image, but the barcode label is susceptible to the effects of voids 4 and spots 5 during printing, which affects reading accuracy. In addition, since the size of the image is limited by the length in the bar width direction, the light receiving area becomes small, and in order to cover the amount of light received, a light source for barcode illumination is required to have a large amount of light.

In the present invention, in order to image a barcode image on the reading line of a photodiode array, which is a photoelectric exchange element of a one-dimensional image sensor, the longitudinal direction of the bar of the barcode scanning image is placed between the barcode label and the reading sensor. By providing a semicylindrical condensing lens to condense the light in the longitudinal direction of the bar in the barcode scanning image onto the reading line, it is possible to effectively utilize the image of the bar in the longitudinal direction of the barcode. As a reading sensor, the light-receiving shape of the photodiode constituting the -dimensional image sensor is designed to have a rectangular light-receiving surface corresponding to the longitudinal direction of the bar in the image for barcode scanning. The objective is to enable viewing of the field of view, which is resistant to the effects of void spots, etc., and enables highly accurate reading.

An embodiment of the present invention shown in the drawings will be described below. Second
The figure is an explanatory diagram showing a schematic arrangement, and FIG. 3 is a partial sectional view showing a detailed configuration. In FIGS. 2 and 3, the illumination light source 6 that illuminates the bark board is a group of incandescent lamps.
The illumination light passes through a semicylindrical illumination lens 7 and illuminates a barcode 8a printed on a barcode label 8. This barcode 8a is coded based on the widths of white and black bars as a shading pattern. Reference numeral 9 denotes a surface reflecting mirror that reflects the reflected light from the barcode 8a in a specific direction.
A scanning image is formed on the reading line No. 2. This reading sensor uses a one-dimensional image sensor that converts the scanning image on the reading line 12a into an electrical signal by electronic scanning operation based on the application of a clock pulse. As shown in FIG. 5, the position of the general protective glass has the effect of converging the longitudinal direction of the barcode image to 1/3 on the light receiving surface of the photodiode 12C. Each light-receiving surface of the photodiode 12c, which has a semicylindrical condensing lens 12b and is a photoelectric conversion element, is arranged so that the ratio of the length of the scanning image in the longitudinal direction to the width direction is 10:1. It has an elongated light-receiving surface.

The one-dot chain line in the optical system shown in FIG. 2 indicates the trajectory of light. Reference numeral 13 denotes an electric control circuit that drives the reading sensor 12 and processes the electric signal therefrom to convert it into a digital signal corresponding to the bar code 8a. 1
Reference numeral 5 indicates an outer case made of synthetic resin for hand-held use, and 16 indicates an inner case, in which a flat reflector 9, a lens 10, an aperture member 11, a reading sensor 12, an illumination light source 6, and an illumination lens 7 are arranged and fixed, and the illumination light source is A reflecting mirror 17 that reflects the illumination light on the reflection side of 6 is fixed.

Next, the operation in the above-mentioned process will be explained. now,
When the reading device is placed at the position shown in FIG. 3 with respect to the barcode label 8 and the illumination light source 6 is turned on, the illumination light from the group of incandescent lamps is focused by the illumination lens 7, and the barcode label is 8 is illuminated. The barcode label 8 has different reflectance according to the printed white and black bars, and a reflected light beam whose light intensity distribution corresponds to the barcode 8a is generated.
A scanning image of the barcode 8a is formed on the reading line 12a of the reading sensor 12 through the barcode 8a.

Therefore, the scanning image is converted into an electrical signal by the electronic scanning reading operation by the electronic sensor circuit 13 of the reading sensor 12, and based on this electrical signal, the electronic control circuit 13 further converts it into a digital code signal, and the external is sending out that signal.

At this time, the one-dimensional image sensor used in the reading sensor 12 has a photodiode array E constituting a semicylindrical condensing lens 12b that functions to condense light in the longitudinal direction of the scanning image. Since the photodiode array is arranged so as to form a scanning image that is reduced to 1/3, the amount of light that enters the photodiode array can be expanded three times. In addition, since the light-receiving surface of the photodiode 12c is arranged in a rectangular shape with a length ratio of the length direction of the bar of the scanning image bar to the width direction of 10:1, the incidence in the longitudinal direction of the bar of the scanning image bar is The amount of incident light is 10 times that of a square-shaped light-receiving surface. Therefore, the synergistic effect of the above two points makes it possible to achieve a reading sensitivity 30 times higher.

Further, the influence of voids and spots can be reduced to 1/30, and highly accurate reading is possible even with the illumination light source 6 with a small amount of light.

Further, in the arrangement of the optical system, it has a lens 10 for imaging the barcode scanning image, and further has a semicylindrical lens 12b for condensing light in the longitudinal direction of the barcode scanning image, By correlating this with the effect of the diaphragm member 11, it is possible to clearly form a barcode scanning image on the reading line 12a, which also allows highly accurate reading.

In addition, the semicylindrical condensing lens 12b that condenses light in the longitudinal direction of the bar of the image for barcode scanning is placed on the one-dimensional image sensor surface, and since the distance from the photodiode array is small, the optical axes are aligned. It is easy to read and is resistant to vibrations, which also makes it possible to read with high precision.

In the above embodiment, the semicylindrical condensing lens 12b is used as the protective glass for the photodiode of the -dimensional image sensor, and has the function of protecting the photodiode and condensing light in the longitudinal direction of the scanning image bar. However, a semicircular condensing lens may be installed separately from the protective glass, and in that case, the condensing lens can be placed between the barcode label and the light receiving surface of the photodiode. You can install it anywhere.

As described above, in the present invention, a semicylindrical condensing lens is provided between the barcode and the reading line to condense light in the longitudinal direction of the bar of the scanning image. By focusing the image on the reading line, it is possible to increase the amount of light incident on the light receiving surface of the photodiode that makes up the reading line, and the light receiving surface of the photodiode has a shape that is elongated in the longitudinal direction of the scanning image bar. Because of the arrangement, a large light-receiving surface can be provided in the longitudinal direction of the scanning image bar.The synergistic effect of the above two points makes it less susceptible to the effects of voids and spots, and requires a small amount of light. This has the excellent effect of enabling highly accurate reading using an illumination light source.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the outline of a conventional one-dimensional image sensor, Fig. 2 is an explanatory diagram showing the schematic arrangement of the optical system of the present invention, Fig. 3 is a partial cross-sectional configuration diagram of Fig. 12, and Fig. 4 1 is a front view of the reading sensor in FIG. 1, and FIG. 5 is a sectional view of the reading sensor in FIG. 4. 6... Illumination light source, 7... Illumination lens, 8... Neue code label, 8a... Barcode, 9... Plane reflector, IO... Lens, 11... Aperture member ,ll
a... Oblate slit, 12... Reading sensor, 12a
...Reading line, 12b...Condensing lens, 12C...
Photodiode row, 13... electronic control circuit. Representative patent attorney Ryuichi Okabe 45'.

Claims (1)

[Scope of Claims] A barcode reading device equipped with a reading sensor that converts a barcode image on a reading line into an electrical signal by an electronic scanning type reading operation, comprising: A lens is arranged to form an image of the barcode image, and a condensing lens is provided to focus the barcode image in the longitudinal direction of the bar, and the reading sensor is provided with a photodiode having an elongated shape in the longitudinal direction of the bar. A barcode reading device characterized by arranging columns.