JPS61289470A - Bar code reader - Google Patents

Abstract

PURPOSE:To maintain focal depth at a deep state and to prevent the reflected light of bar codes from reducing by converging light on a direction intersected with the longitudinal direction of a photodetecting element array for reading out the reflected light through cylindrical lenses. CONSTITUTION:Light emitting diodes (LEDs) 11-13 are arranged as light sources and a wide lens array 20 is arranged oppositely to the LEDs 11-13. The wide angle lens array 20 has fine wide lenses 21-27 and these wide angle lenses 21-27 diverge light on the almost same direction as the array direction of the LEDs 11-13. Each of the wide angle lenses 21-27 consists of a cylindrical lens or a polygonal lens. Bar codes 31 are recorded on a label 30, and when light is irradiated from the LEDs 11-13 to the bar codes 31, the reflected light is read out.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a barcode reading device.

[Prior Art] A conventional eight-code reading device is a device that illuminates a coded gray pattern (barcode) and reads reflected light from the barcode using an electronic scanning type light receiving element array.

In the conventional example L, it is necessary to increase the depth of focus in order to prevent out-of-focus of the 8-code, and for this reason, the circular aperture hole serving as the aperture means is made small. Another problem is that in order to clearly image the 8-code on the light receiving element array, an illumination device with a large amount of light must be used.

On the other hand, if the aperture of the diaphragm is made larger, the amount of light received on the photodetector array will increase, but the depth of focus will become shallower.
Another problem arises in that barcode pins are likely to be misaligned.

``Object of the Invention'' The present invention has been made by focusing on the above-mentioned conventional problems, and provides a barcode reading device that can maintain a deep depth of focus and prevent the amount of reflected light from the barcode from decreasing. The purpose is to

[Embodiment of the Invention] FIG. 1 is a perspective view showing an embodiment of the present invention, and shows an example of an illumination system.

LEDIs 1.12.13 are provided as light sources, and a wide-angle lens array 20 is provided facing them. This wide-angle lens array 20 includes a fine wide-angle lens 21
, 22, 23, 24, 25°26.27, and these wide-angle lenses 21 to 27 spread light in substantially the same direction as the arrangement direction of the LED IIs and 12.13. Each of the wide-angle lenses 21 to 27 is a cylindrical lens or a polygonal lens.

An eight-code 31 is recorded on the label 30, and this barcode 31 is irradiated with light from LEDs II to 13, and the reflected light is read through a condensing system, which will be described later.

Next, the operation of the above embodiment will be explained.

FIG. 2 is an enlarged view of the embodiment shown in FIG. tIIJ1, as seen from the front.

In Figure 2, focusing on LED II, this LED
The light from II is once focused by the wide-angle lens 22, and then spread out. And this widened width is the LED
The barcode 31 on the label 30 is irradiated over a wide range in order to be wider than the width of the label II. Similarly, LEDI
2.13, once with wide-angle lens 24.26,
Since the light is focused and then widened, the width of each beam becomes wider.

FIG. 3 is a diagram showing the change in brightness for the second place on the label.

In FIG. 3, waveform 11a is the luminance distribution illuminated by LED II, and waveform 12a.

13a shows the luminance distribution irradiated by LEDI2.13 respectively.0 composite moderation T is the waveform 11
a, 12a, and 13a, and its amplitude (
In other words, if the wide-angle lens array 20 did not exist in the above embodiment, the brightness on the label 30 would change greatly, and when the reflected light at this time was read, The probability of the reading error increases.

In other words, if the non-bar part of a barcode overlaps with the dark part of the light source's stripes, it will be mistakenly determined that a bar exists, and conversely, if the bar part overlaps with the bright part of the light source's stripes, It is incorrectly assumed that the bar does not exist.

Of course, increase the number of LED II-13 and use the above LED
The narrower the interval, the smaller the reading error. However, installing a large number of LEDs causes various problems.

In the above embodiment, even if the number of LEDs 11 to 13 is small, the variation in the brightness distribution is small, so the reading error is small, and even if one LED is provided, the brightness distribution is small. For example, light from LED II illuminates the barcode 31 through the wide-angle lens 21 or 23, but since the amount of light is relatively small, it will be omitted for the sake of explanation.

In addition, each of the wide-angle lenses 21 to 27 in FIG. 1 has a convex surface on the same side as LED II-13, and
If the surface opposite to -13 is made concave, the light emitted from the wide-angle lens array 20 will be parallel, the brightness distribution will be flat, and the amount of light that curves to the outside of the barcode 31 can be reduced. , efficient lighting can be performed.

Further, each of the wide-angle lenses 21 to 27 may be a toric lens. Further, in the above embodiment, each of the wide-angle lenses 21 to 27 is a convex lens.
These may be concave lenses, that is, even if each of the wide-angle lenses 21 to 27 is a concave lens, the LED
It is possible to spread the light from I to 13.

FIG. 4 is a perspective view showing another embodiment of the present invention, and shows a condensing system.

A barcode 31 is printed on the label 30, and this eight-
The cord 31 receives irradiation from the illumination system shown in FIG. 1 or 2, and is provided with an aperture f stage 40 that narrows down the reflected light. A light-receiving element array 51 is provided to read the reflected light focused by the first stage 40 of the aperture. This light receiving element array 51 is arranged in a line on the surface of the light receiving element f-50.

A cylindrical lens 60 is provided between the light-receiving element array 51 and the first aperture stage 40, and this cylindrical lens 60 focuses light in a direction perpendicular to the longitudinal direction of the light-receiving element array 51.

Next, the operation of the above embodiment will be explained.

FIG. 5 is a left side view of the embodiment shown in FIG. 4.

The reflected light from the eight-code 31 is narrowed down by the diaphragm means 40, and the depth of focus is increased by this diaphragm, so that even if the position of the bar code 31 is slightly shifted, reading can be performed satisfactorily. The light passing through the aperture means 40 is condensed by a cylindrical lens 60 and arranged at a light receiving element array 51.
The image is formed on the .

In this case, the cylindrical lens 60 focuses the light in a direction perpendicular to the longitudinal direction of the light receiving element array 51 without changing the dispersion state of the light in the longitudinal direction of the light receiving element array 51. For this reason, if there were no cylindrical lens 60, the light receiving element array 51 would receive the light that deviates from the light receiving element array 51.
1 allows for brighter reflected light.

Therefore, if the amount of light received on the light-receiving element array 51 is kept the same, the brightness of the illumination system can be made lower than before or the number of LEDs can be reduced.

In the embodiment E, the cylindrical lens 60 is
Although the light is focused in a direction perpendicular to the longitudinal direction of the light receiving element array 51, the light may be focused not only in a direction perpendicular to the longitudinal direction but also in a direction intersecting with the longitudinal direction.

Further, in the above embodiment, the aperture of the aperture means 40 is a small circle, but it may be formed into a slit shape.If it is formed into a slit shape in the same direction as the longitudinal direction of the light receiving element array 51, The amount of light received at is further increased.

[Effects of the Invention] According to the present invention, the depth of focus can be maintained deep, and the light receiving element can receive a large amount of reflected light from the barcode.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention. FIG. 2 is an enlarged view of the above embodiment. FIG. 3 is a characteristic diagram showing luminance changes with respect to position in the above embodiment. FIG. 4 is a perspective view showing another embodiment of the present invention. FIG. 5 is a left side view of the embodiment shown in FIG. 4. 11-13... LED as lighting means, 20...
Wide-angle lens array, 21-27... wide-angle lens, 30... label, 31... barcode, 40... aperture means, 51... light receiving element array, 60... cylindrical lens, patent application People Optoelectronics Co., Ltd. Figure 3

Claims (7)

[Claims] (1) A barcode reading device comprising: a light-receiving element array that reads reflected light; and a cylindrical lens that focuses light in a direction intersecting the longitudinal direction of the light-receiving element array. (2) The barcode reading device according to claim 1, further comprising a diaphragm means for narrowing down the reflected light, and the diaphragm means has a small circular shape or a slit shape. (3) In claim 1, an illumination means for illuminating the barcode is provided, and the illumination means includes at least one light source and a fine wide-angle light source extending in substantially the same direction as the arrangement direction of the light source. A barcode reading device comprising a wide-angle lens array in which a plurality of lenses are arranged in a row. (4) The barcode reading device according to claim 3, wherein the wide-angle lens is a cylindrical lens or a polygonal lens. (5) The barcode reading device according to claim 3, wherein the wide-angle lens is a toric lens. (6) The barcode reading device according to claim 3, wherein the wide-angle lens has a convex surface on the same side as the light source and a concave surface on the opposite side from the light source. (7) The barcode reading device according to claim 3, wherein the wide-angle lens is a concave lens.