JPS648876B2 - - Google Patents

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 one-dimensional image sensor is used as a reading sensor 1 in a device that reads barcodes, that is, reflected light from 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 light is the length in the longitudinal direction of the barcode scanning image 3 that is imaged on the one-dimensional image sensor. The ratio of the length and the length in the direction intersecting 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. Then,
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. Furthermore, 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 compensate for the amount of light received, a light source for bar code 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, light is focused in the longitudinal direction of the bar code scanning image between the lens and the reading sensor. By installing a condensing lens to focus the longitudinal direction of the bar in the barcode scanning image onto the reading line, it is possible to not only effectively utilize the image of the bar in the longitudinal direction of the barcode, but also to focus the light onto the photodiode array. The purpose of this invention is to be able to increase the amount of light that is detected, thereby making it resistant to the effects of void spots and the like, and to enable highly accurate reading.

An embodiment of the present invention shown in the drawings will be described below. FIG. 2 is an explanatory diagram showing the general arrangement, and FIG. 3 is a partial sectional view showing the detailed configuration. In FIGS. 2 and 3, the illumination light source 6 that illuminates the barcode is a group of incandescent lamps, and the illumination light passes through a semicylindrical illumination lens 7 for the barcode printed on the barcode label 8. 8a is illuminated. 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 fixed direction, and the reflected light passes through the lens 10 and the aperture member 1 having a flat slit 11a.
1, and a scanning image is formed on the reading line of the reading sensor 12. 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 focusing the longitudinal direction of the barcode image to 1/3 on the light receiving surface of the photodiode 12C. Kamaboko-shaped condensing lens 1
2b, and the light-receiving surface of each photodiode 12c, which 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. have.

The one-dot chain line in the optical system shown in FIG. 2 indicates the trajectory of light. Reference numeral 13 denotes an electrical control circuit that drives the reading sensor 12 and processes electrical signals from the reading sensor 12 to convert them into digital signals corresponding to the barcode 8a. Reference numeral 15 indicates an outer case made of synthetic resin for hand-held use, and 16 indicates an inner case in which the flat reflector 9, lens 10, aperture member 11, reading sensor 12, illumination light source 6, and 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 of the above configuration 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, The code label 8 is illuminated. The barcode label 8 has different reflectance depending on the printed white and black bars, and a reflected light beam whose light intensity distribution corresponds to the barcode 8a is generated. 1
A scanning image of the barcode 8a is formed on the reading line 12a of the reading sensor 12 through the barcode 1a. Therefore, the scanning image is converted into an electrical signal by the electronic scanning reading operation by the electronic sensor circuit 13 of this reading sensor 12, and based on this electrical signal,
Furthermore, the electronic control circuit 13 converts it into a digital code signal and sends the signal to the outside.

At this time, the one-dimensional image sensor used in the reading sensor 12 has a semicylindrical condensing lens 1 that functions to condense light in the longitudinal direction of the scanning image.
Since the scanning image is formed on the photodiode row constituting 2b by reducing the longitudinal direction of the bar to 1/3, the amount of light entering the photodiode row can be expanded by 3 times. I can do it. In addition, since the light-receiving surface of the photodiode 12c is arranged in a rectangular shape with a length ratio of 10:1 between the longitudinal direction and the width direction of the bar of the scanning image, the incidence in the longitudinal direction of the bar of the scanning image 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.

In addition, the effects of voids and spots can be reduced to 1/30, making it possible to reduce the effects of voids and spots by 1/30, making it possible to
However, highly accurate reading is possible.

In addition, in the arrangement of the optical system, it has a lens 10 for imaging an image for barcode scanning, a semicylindrical lens 12b for condensing light in the longitudinal direction of the image for barcode scanning, and an aperture member. By correlating the effects of 11, it is possible to clearly form a barcode scanning image on the reading line 12a, and this 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 axis is aligned. It is easy to read and is resistant to vibrations, which also makes highly accurate reading possible.

In the above embodiment, the semicylindrical condensing lens 12b is used as the protective glass for the photodiode of the one-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 semi-cylindrical 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 condensing lens for condensing light in the longitudinal direction of the bar of the scanning image is provided between the lens that forms an image of the barcode image and the reading line. By focusing the longitudinal 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 it is less susceptible to the effects of voids and spots.
This has the excellent effect of enabling highly accurate reading using a light source for illumination with a small amount of light.

[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. This figure 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...Barcode label, 8a...Barcode, 9...Plane reflector, 10...Lens, 11...Aperture member,
11a... flat slit, 12... reading sensor,
12a...Reading line, 12b...Condensing lens, 12
c...Photodiode array, 13...Electronic control circuit.

Claims (1)

[Scope of Claims] 1. A barcode reading device equipped with a reading sensor arranged with a photodiode array and converting a barcode image on a reading line into an electrical signal through an electronic scanning type reading operation, comprising: reading of the reading sensor; a lens disposed between the line and the barcode to form an image of the barcode image; and a lens disposed between the reading line of the reading sensor and the lens to form an image of the barcode image in the longitudinal direction of the bar of the barcode image. A barcode reading device comprising: a condensing lens that condenses light.