JPS61289471A - Bar code reader - Google Patents

Abstract

PURPOSE:To prevent bar codes from uneven light irradiation and to increase the effective light projection upon the bar codes by arranging a wide angle lens array for diverging light on the almost same direction as the array direction of illuminating light sources and a photodetecting element array for reading out the reflected light of the bar codes. CONSTITUTION:The reflected light from the bar codes 31 is stopped by a diaphragm means 40, and even if the positions of the bar codes 31 are slightly shifted, the reflected light can be sufficiently read out because the focal depth is increased by said stopping. Light passed through the diaphragm means 40 is converged by a sylindrical lens 60 and forms its image on the photodetecting element array 51. In this case, the cylindrical lens 60 converges the light on the direction rectangular to the longitudinal direction of the array 51 without changing the light dispersing state in the longitudinal direction of the array 51. If the cylindrical lens 60 does not exist, light deviated from the array 51 is received by the array 51, so that the array 51 can obtain more brighter reflected light.

Description

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

[Prior Art] A conventional barcode 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.

Furthermore, in the conventional example described above, in order to accurately recognize barcodes, it is necessary to provide even illumination. For this purpose, a large number of illumination light sources are used.

In order to provide even illumination and reduce the number of illumination light sources, the light from the illumination light sources may be passed through ground glass or the like.

However, when ground glass is used, there is a problem in that the effective amount of light that reaches the barcode is extremely small.

``Object of the Invention'' The present invention has been made by focusing on the above-mentioned conventional problems.It is an object of the present invention to reduce the unevenness of light on a barcode, and to increase the amount of effective light emitted from an illumination light source to the barcode. The purpose of this invention is to provide a barcode reading device that can perform the following functions.

[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.

LED II, 12, 13 are provided as light sources, and a wide-angle lens array 20 is provided facing these.

This wide-angle lens array 20 includes fine wide-angle lenses 21,
22, 23, 24, 25°26.27, and these wide-angle lenses 21-27 are LED II, 12. [3] The arrangement direction is to widen the angle of light in the same direction. Each of the wide-angle lenses 21 to 27 is a cylindrical lens or a polygonal lens.

A barcode 31 is recorded on the label 30, and this barcode 31 receives light from the LEDs 11 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. 1, 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 so that the width is wider than the width of the barcode 31 on the label 30. Similarly, L.E.
In each case of D12.13, the light is once focused by the wide-angle lens 24.26 and then widened, so that the width of each light becomes wide.

FIG. 3 is a diagram showing changes in brightness with respect to position on the label.

In the m3 diagram, waveform 11a is the luminance distribution irradiated by LED II, and waveform 12a.

13a shows the luminance distribution irradiated by the LEDs 12 and 13, respectively. The composite sieve degree T is the waveform 11.
It is a composite of 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 possibility of reading errors increases.

In other words, if the non-bar part of the 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 LHDs 11 to 13, and
If the interval D is narrowed, the reading error will be reduced. However, when LEDs are installed in multiple shells, various problems arise.

In the above embodiment, even if the number of LED II-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 the LEo 11 to 13, and
If the surface opposite to 1 to 13 is made concave, the light emitted from the wide-angle lens 7 ray 20 will be parallel, the 1 degree distribution will be flat, and the amount of light deflected to the outside of the barcode 31 will be reduced. This makes it possible to provide efficient lighting.

Further, each of the wide-angle lenses 21 to 27 may be a toric lens. Furthermore, each of the wide-angle lenses 21 to 27 in the above embodiment 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 barcode 31 receives irradiation from the illumination system shown in FIG. 1 or 2, and is provided with an aperture means 40 for narrowing down the reflected light. A light-receiving element array 51 is provided to read the reflected light focused by the f-stage diaphragm 40. The light receiving element array 51 is arranged in a line on the surface of the light receiving element 50.

A cylindrical lens 60 is provided between the light receiving element array 51 and the aperture means 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 barcode 31 is narrowed down by the aperture means 40, and the depth of focus is increased by this aperture, so that even if the position of the barcode 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 above embodiment, 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 diaphragm 40 is a small circle, but it may be formed into a slit shape.If the slit shape is formed in the same direction as the longitudinal direction of the light receiving element array 51, the light receiving element array 60 The amount of light received at is further increased.

[Effects of the Invention] According to the present invention, there is little unevenness in the light of the barcode-L,
Moreover, it has the effect of increasing the effective amount of light that reaches the barcode from the illumination light source.

[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 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 applicant: Optoelectronics Co., Ltd. Figure 3

Claims (7)

[Claims] (1) at least one light source that illuminates the barcode; a wide-angle lens array that spreads light in substantially the same direction as the array direction of the light source and that includes a plurality of fine wide-angle lenses arranged in a row; A barcode reading device comprising: a light receiving element array for reading reflected light from a code; and a barcode reading device. (2) The barcode reading device according to claim 1, wherein the wide-angle lens is a cylindrical lens or a polygonal lens. (3) The barcode reading device according to claim 1, wherein the wide-angle lens is a toric lens. (4) The barcode reading device according to claim 1, wherein the wide-angle lens has a convex surface on the light source side and a concave surface on the opposite side from the light source. (5) The barcode reading device according to claim 1, wherein the wide-angle lens is a concave lens. (6) The bar code according to claim 1, further comprising a cylindrical lens provided between the light receiving element array and the aperture means to condense light in a direction intersecting the longitudinal direction of the light receiving element array. reading device. (7) The barcode reading device according to claim 6, wherein the aperture means has a small circular shape or a slit shape.