JPS6273387A - Bar-code reader - Google Patents

Abstract

PURPOSE:To prevent a level drop of an electric signal outputted from a photodetecting element, and to improve the read accuracy by providing a reflecting member so that a beam which has been reflected in the direction being different from the photodetecting element side can also be turned to the photodetecting element side. CONSTITUTION:A surface to be scanned F provided with a bar-code is brought to an optical scan by an optical beam, a reflected light is photodetected by photodetecting elements 4a, 4b and read of the bar-code is executed. On the outside of these elements 4a, 4b, reflecting members 5a, 5b are provided, and a reflected light in the direction being different from the elements 4a, 4b is also reflected by the members 5a, 5b and made incident on the elements 4a, 4b. Accordingly, the photodetecting quantity of the elements 4a, 4b increases, a level drop of a part corresponding to the center and both sides of the scanning face F of an electric signal outputted from the elements 4a, 4b is prevented, the bar-code read accuracy is improved, and the bar-code which has been deteriorated due to contamination, etc. can also be read.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a light source that irradiates a light beam onto a surface to be scanned, an optical system that focuses the light beam onto the surface to be scanned, and a light source that directs the light beam in a direction parallel to barcodes. The present invention relates to a barcode reader having a light beam scanning means for scanning, and a light receiving element that receives light reflected from the surface to be scanned, converts it into an electric signal according to the intensity of the light, and outputs the electric signal.

BACKGROUND OF THE INVENTION Conventionally, barcode readers of this type generally have a 5th barcode reader.
It was configured as shown in the figure. In this figure, ■ is a light source that irradiates a light beam onto the scanned surface F formed by the barcode surface, 2 is a convergence lens (optical system) that converges the light beam onto the scanned surface F, and 3 is a scanning mirror for scanning a light beam in the parallel direction of barcodes. 4 is a light-receiving element that receives the light reflected from the scanned surface F, converts the light received by this light-receiving element 4 into an electrical signal, and converts the information recorded in the barcode according to the strength of the electrical signal. Configured to read.

However, in the case of the conventional example having such a configuration, there is a drawback that the light receiving device deteriorates at both ends of the scanned surface F in the scanning direction, resulting in so-called blurring. That is, a blank sheet of paper is placed on the surface to be scanned F and the light beam is scanned,
If we look at the output change of the reflected light from the scanned surface F at each position of the scanned surface F in the scanning direction, as shown in FIG. It is clear that at both ends, the amount of light received by the light receiving element 4 decreases, and the output level from the light receiving element 4 decreases. If the output level decreases in this way, when converting it into an electrical signal and decoding a barcode, the output level of the reflected light from the white area at both ends in the scanning direction and the reflected light from the black area at the center side in the scanning direction will be reduced. The level difference with the output level of
Even the slightest amount of dirt can easily cause errors in decoding, resulting in a reduction in reading accuracy.

Therefore, in order to reduce such changes in the output level, two light receiving elements are provided at a predetermined interval in the scanning direction of the scanned surface F, as shown in Japanese Patent Laid-Open No. 56-140467. There is something. When two light receiving elements are provided, the following two forms can be considered, and each of them will be considered.

(i) First Form As shown in FIGS. 7 and 8(a), the first and second light-receiving elements 4a and 4b are provided with their light-receiving surfaces parallel to the scanned surface F, respectively.

In this case, if we look at the output change of the reflected light from the scanned surface F in the same manner as described above, as shown in FIG. So,
The outputs from both light receiving elements 4a and 4b are added together, making it possible to avoid a decrease in the output level. However, although the decrease in the output level at both ends of the scanned surface F in the scanning direction can be halved compared to when there is only one light-receiving element, since there is no addition of outputs as at the center side, the output There is a drop in the level.

(11) Second form As shown in FIGS. 9 and 10(a), each of the first and second light receiving elements 4a, 4b has its light receiving surface facing toward the end of the scanned surface F in the scanning direction. It is provided so that it is facing outward, that is, facing outward.

In this case, if we look at the change in the output of the reflected light from the scanned surface F as described above, as shown in Figure 1O (b),
Within the scanning area, a decrease in the output level at both ends of the scanned surface F in the scanning direction is suppressed. However, in each of the first and second light receiving elements 4a and 4b, the output level at the center side decreases, so both light receiving elements 4
Even if the outputs from a and 4b are added together, the output level at the center will decrease, and the output level will decrease at three locations, at both ends in the scanning direction and at the center, resulting in unevenness as a whole. It's inconvenient.

The present invention has been made in view of the above circumstances, and it is possible to avoid a decrease in the amount of light received by the light receiving element not only at the center side in the scanning direction of the surface to be scanned, but also at both end sides in the scanning direction. It is an object of the present invention to improve reading accuracy by eliminating a drop in the level of an electrical signal output from an element.

Means for Solving the Problems The present invention aims to increase the number of light beams that reach the light receiving element from the light source through the scanned surface by reflecting light that was not incident on the light receiving element in the past. A reflective member was provided to guide the light.

action FIG. 1(a) provides a detailed explanation of the invention.

In this figure, 4a and 4b are first and second light receiving elements, and 5a and 5b are reflective members provided on the outside of each of the first and second light receiving elements 4a and 4b. With this configuration, apparent light-receiving elements 4a' and 4b' corresponding to the first and second light-receiving elements 4a and 4b are provided on the outside of each of the reflecting members 5a and 5b. As a result, as shown in FIG. 1(b), the outputs of the first and second light receiving elements 4a and 4b at both ends in the scanning direction of the surface to be scanned F within the scanning area,
The outputs from the corresponding apparent light-receiving elements 4a' and 4b' are added, and the output level not only at the center side of the scanned surface F in the scanning direction but also at each self-portrait end side in the scanning direction is made to be as high as the center side. can.

EXAMPLES Hereinafter, the present invention will be explained in detail based on examples shown in the drawings. FIG. 2 is a partially cutaway side view of a barcode reader A according to an embodiment of the present invention, and FIG. 3 is a perspective view showing a schematic configuration for reading barcodes. In these figures, ■ is a light source composed of a light emitting diode, etc., 2 is an optical system composed of a converging lens, 3 is a scanning mirror, and 4a and 4b each have a light receiving surface that is the scanned surface F. The light receiving elements are arranged in a parallel orientation, and their respective functions are as described above, and their explanations will be omitted here. 5 a and 5 b are each reflective members,
Reference numeral 6 denotes an electric circuit that amplifies and smoothes the electric signal that is photoelectrically converted by the light-receiving elements 4a and 4b and is outputted therefrom, performs A/D conversion, and reads the information recorded on the barcode according to the strength of the electric signal. Department.

An electric motor 7 is interlocked with the scanning mirror 3;
A light beam scanning means 8 is configured to drive and rotate the scanning mirror 3 to scan the light beam converged on the scanned surface F in the parallel direction of the barcodes.

These members are attached to the support member 9 and housed in a main body 11 having a grip portion lO. This main body 11 is formed with an opening 12 through which the light beam from the scanning mirror 3 passes, and the edge of this opening 12 is brought into contact with the barcode attachment B to maintain a predetermined posture when reading the barcode. It is structured so that it can be maintained.

Reference numeral 13 denotes a switch section, and by pressing the switch section 13 while the edge of the opening 12 is in contact with the barcode attachment B, barcode reading can be started. There is.

On the inner surface of the peripheral part of the opening 12 of the main body 11, a surface to be scanned is located between the surface to be scanned F and the light receiving elements 4a and 4b, and at both ends mar of the surface to be scanned F in the scanning direction. F
The reflecting members 5a and 5b are provided so as to reflect the light reflected in a direction different from the light receiving elements 4a and 4b toward the light receiving elements 4a and 4b. The reflecting members 5a and 5b may be made of dedicated mirror members, or may be made by finishing the inner surface of the main body 11 with a mirror finish.

The reflecting members 5a and 5b are not limited to those provided perpendicularly to the scanned surface F as in the above-mentioned embodiments, but for example, as shown in FIG. In other words, at both ends of the scanned surface F in the scanning direction, the light beam reflected from the scanned surface F in a direction different from that of the light receiving elements 4a and 4b is transmitted to the light receiving elements 4a and 4b. It is sufficient if the light can be reflected toward the side, and the mounting posture thereof may be appropriately set based on the relative relationship between the light receiving elements 4a, 4b and the surface to be scanned F.

In the above embodiment, two light receiving elements 4a and 4b are provided, and one
However, in the present invention, it is possible to reduce the sensitivity unevenness and increase the amount of received light compared to the case where one is provided. However, in the present invention, it is possible to reduce sensitivity unevenness and increase the amount of received light by providing one or three or more. It may also be something that allows it to increase. That is, in order to increase the amount of light reflected from the surface F to be scanned, it is preferable to bring the light receiving elements 4a and 4b close to the surface F to be scanned. However, the closer the light receiving elements 4a and 4b are brought to the scanned surface F, the more likely it is that uneven sensitivity will occur in the scanning direction of the light beam with respect to the scanned surface F, and the length in the scanning direction that will not cause sensitivity unevenness will be shortened. Become. Therefore, by increasing the number of light receiving elements 4a and 4b,
By adding the outputs of the adjacent light-receiving elements 4a and 4b, it is possible to avoid a decrease in the output level due to uneven sensitivity, and increase the amount of received light with less uneven sensitivity.

The light beam scanning means 8 is configured such that the light source 1 and the optical system 2 are integrally provided in a case, and the case is driven and rotated by an electric motor to scan the surface F to be scanned with the light beam. It may be something that constitutes.

As described above, according to the present invention, no matter where the scanning position of the light beam is in the scanning direction of the surface to be scanned, if the reflectance from there is the same for white and black, it is equal. Alternatively, it is possible to receive approximately the same amount of reflected light, eliminating changes in the level of the electrical signal output from the light-receiving element. This makes it possible to successfully avoid erroneously decoding parts such as white parts, and it is now possible to read the information recorded in barcodes with high accuracy. In particular, in a barcode reader that uses a light emitting diode as a light source, the light beam is weak and the reading accuracy is greatly affected by changes in the amount of received light, so the present invention can be effectively applied. .

[Brief explanation of drawings]

FIG. 1(a) is a schematic plan view for explaining the operation of the embodiment of the present invention, and FIG. 1(b) is a schematic plan view of the embodiment of the present invention.
A graph showing the correlation between the change in the output of reflected light from the surface to be scanned and the scanning position with respect to the surface to be scanned, FIG. 2 is a partially cutaway side view of a barcode reader according to an embodiment of the present invention, and FIG. FIG. 4 is a schematic plan view showing another embodiment; FIG. 5 is a perspective view showing the schematic structure of a conventional example; and FIG. 6 is a conventional example. 7 is a graph showing the correlation between the output change of the reflected light from the surface to be scanned and the scanning position with respect to the surface to be scanned, and FIG. 7 is a perspective view showing the schematic configuration of the first form in another conventional example, and FIG. (a
) is a schematic plan view for explaining the operation of the conventional example shown in FIG. 7, and FIG. FIG. 9, a graph showing the correlation between the scanning position and the scanning plane, is a perspective view showing the schematic configuration of the second form in another conventional example, and FIG.
a) is a schematic plan view for explaining the operation of the conventional example shown in FIG. 9, and FIG. 10(b) shows changes in the output of reflected light from the scanned surface in the conventional example shown in FIG. It is a graph showing the correlation between the scan position and the surface to be scanned. ■...Light source, 2...Optical system, 4a, 4b...Light receiving element, 5a, 5b...Reflecting member, 8...Light beam scanning means, F...Scanned surface.

Claims (1)

[Claims] (1) a light source that irradiates a light beam onto a surface to be scanned, an optical system that focuses the light beam onto the surface to be scanned, and a light beam scanning device that scans the light beam in a parallel direction of the barcode; A barcode reader having a light receiving element that receives light reflected from the surface to be scanned, converts it into an electric signal according to its intensity, and outputs it, wherein the light receiving element is provided between the surface to be scanned and the light receiving element. Reflecting members are provided at each end of the scanned surface in the scanning direction to reflect the light reflected from the scanned surface in a direction different from the light receiving element toward the light receiving element. A barcode reader characterized by: