JPH04219880A - Optical reader - Google Patents

Abstract

PURPOSE:To improve the read operation efficiency by reading only a bar code that a user intends at all times and securing the read of the bar code by the optical reader. CONSTITUTION:When there are plural bar code images in the scanning range of a scanner and at least part of the bar code images is present in a constant range <N-M,N+M> at the center part of the scanning range, a bar code touching the center of the scanning range or a bar code which is the closest to the center of the scanning range among those bar code images is recognized, but when no bar code image is included in the constant range at the center part, no bar code is recognized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical reading device for reading symbols such as characters and codes displayed on the surface of an object. Among these, an optical reading device that reads characters displayed on the surface of an object is called an OCR (optical character reading device), and an optical reading device that reads barcodes is called a BCR (barcode scanner).

[0002]Furthermore, the above-mentioned optical reading device includes a hand-held type in which the housing is held in the hand, irradiates light toward an object, and receives the reflected light to read symbols, and there are also types in which the housing is fixed. There is also a fixed type, in which several laser beams are scanned in multiple directions, and the symbol can be read simply by holding an object over the laser beam. Hand-held devices include laser scanners, which optically scan a laser beam and illuminate a distant object;
There is a touch scanner that receives reflected light from an object by bringing a reading window of an optical reading device into contact with an object.

0003

[Prior Art] Barcodes and characters (hereinafter referred to as "barcodes") read by optical reading devices are
There are various sizes. Therefore, in order to accommodate a somewhat wide range of targets, optical reading devices generally have a scanning range that matches wide barcodes.

[0004] For this reason, in situations where large and small products with barcodes are mixed together, such as in POS cash register operations or transportation industry pickup and delivery operations, multiple barcodes often fall within the scanning range. happen. In particular, in the case of a laser scanner, such a situation becomes more likely to occur because the reading depth is deep and barcodes can be read even at different distances from the scanner (see FIG. 8).

[0005] Optical reading devices recognize the contents of barcodes by processing the image of the barcode that enters the scanning range, but when multiple barcodes enter the scanning range at the same time, which one should be recognized? Conventionally, barcodes processed earlier in time are recognized (
(the former), or, out of caution, reading was suspended when multiple barcodes were entered (the latter).

[0006]

[Problem to be solved by the invention] If the former is adopted,
A user may read the barcode of a product that he or she did not intend, and this may result in an irreversible error. In the latter case, a fatal error will not occur, but in a cluttered work environment, imposing a condition on the worker to never include any extra barcodes within the scanning range is This places an excessive burden on workers and causes a decline in work efficiency.

[0007] The above-mentioned problems also occur in OCR. Since the scanning range in OCR is two-dimensional, there is a possibility that a plurality of character strings are lined up within the scanning range more than in BCR. The present invention was made in view of the above problem, and even if multiple barcodes and other symbols fall into the scanning range at the same time, only the one that the user intended to read can be recognized. The purpose of the present invention is to provide an optical reading device.

[0008]

[Means for solving the problem] In general, regardless of whether the scanner is a touch scanner or a laser scanner, the user consciously or unconsciously moves the symbol he or she wants to read to the center of the scanner. Never attempt to read symbols at the edge of the read scanning range. As described above, even when a plurality of symbols enter the scanning range at the same time, the target symbol is included near the center of the scanning range, and other symbols are included at the periphery of the scanning range.

To achieve the above object, the optical reading device of the present invention includes symbol position detection means for detecting the position where an image of the symbol obtained by scanning exists within the scanning range; If at least some of the symbol images detected by the symbol position detection means exist in a certain range of the part, the symbol image closest to the center of the scanning range is identified and detected by the symbol position detection means. symbol image identifying means that does not identify the symbol image if the symbol image is not included in a certain range in the center of the scanning range; and symbol recognition means that recognizes the content of the symbol identified by the symbol image identifying means. It is something that you have.

0010

[Operation] With the above optical reading device, if at least a part of the symbol images exists in a certain range at the center of the scanning range, the symbol closest to the center of the scanning range or the center If the symbol image is not included in a certain range at the center of the scanning range, the symbol can not be identified. Therefore, even when a plurality of symbols enter the scanning range at the same time, the target symbol is located near the center of the scanning range, so that only the target symbol can be read.

[0011] Note that if the "certain range in the center of the scanning range" is too small, operability will be impaired.
It is preferable to set it in consideration of the size of the image when the symbol to be read appears in the scanning range.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples will be explained in detail below with reference to the accompanying drawings showing examples. Figure 2 shows how to read symbols such as barcodes.
Figure 1 shows a hand-held optical reader with laser beam output.
shows a functional block diagram of an electric circuit including a microcomputer. This optical reader includes a pistol-shaped housing 1, a semiconductor laser oscillation device 2, an aberration lens 3 that focuses the output light of the semiconductor laser oscillation device 2, and a rotary lens that scans the output light over a fixed angular width. A polygon mirror 4 of the formula, a motor 11 that rotationally drives the polygon mirror 4.
, a light-receiving element 7 such as a CCD, which receives light that is emitted from the opening 13 at the tip of the housing 1, hits a plurality of barcodes 6a and 6b placed a distance D apart, and is reflected, and the light that is reflected from the polygon mirror surface. The scan detection light receiving element 12 is installed at the end of the effective scanning angle range of the reflected light and directly receives the reflected light, and the output signals of the light receiving element 7 are waveform-shaped.
Binarize to obtain an image signal S2 containing a signal (barcode signal) corresponding to the shape of the barcode to be read,
Based on this image signal S2, the processing section 9a identifies the contents of the barcode according to the control procedure of the present invention, and a synchronization signal for waveform shaping and binarization of the output signal of the scanning detection light receiving element 12 to define the scanning range. It houses a board 9 on which a processing section 9b for producing S1 is mounted. A code 10 coming out of the casing 1 is a signal code for providing an output signal from the processing section 9a to the outside, and a lever 8 serves as a reading switch for an optical reading device.

FIG. 3 is a diagram showing the positional coordinates of each part of the scanning range of the light receiving element 7. Both ends of the scanning range are 0 and 2N, respectively, the center of the scanning range is N, and the reading zone in the center of the scanning range is 0 and 2N. Both ends are indicated by NM and N+M. FIG. 4 is a waveform diagram of the synchronization signal S1 and the image signal S2, and both ends of the scanning range of the light receiving element 7 are temporally defined by the synchronization signal S1. An image signal S2 including two barcode signals is drawn within the scanning range. Both ends of the two barcode signals are b1 and e1, respectively.
, b2, e2.

FIG. 1 is a block diagram showing the main parts of the processing sections 9a and 9b, and an image signal S2 representing a read barcode image is input to a symbol position detection section 91. The symbol position detection unit 91 detects the position coordinates <bi,ei>(i=1,2) of both ends of the barcode included in the image signal S2.
, ...) is output. Here, the subscript i is a number corresponding to each barcode that enters the scanning range at the same time. The symbol image specifying section 92 determines, based on the position coordinate signal S3, that at least a part of the symbol image detected by the symbol position detecting section 91 exists in a reading zone <N-M, N+M> at the center of the scanning range. case,
Among these symbol images, the symbol image closest to the center N is identified, and if the symbol image detected by the symbol position detection section 91 is not included in the reading zone, the symbol image is not identified. be. A signal S representing the position coordinates <b, e> of both ends of the symbol image identified as a result of this processing
4 enters the symbol recognition unit 93, and the symbol recognition unit 93 generates the barcode signal S2 based on this position coordinate signal S4.
decipher and recognize the contents of the target barcode.

FIG. 5 is a flowchart showing the processing procedure of the symbol image specifying section 92. In step (1), the position coordinates of both ends of the barcode <bi, ei> (i=
1, 2, ..., n), and in step (2), first set i = 1 for the first barcode (the order of barcodes is arbitrary), and find the shortest distance between the barcode and the center. Let M be a numerical value Dmin indicating distance. Step (
3) It is determined whether i=n, and if i=n, then in step (4) it is determined whether ei <N-M or bi >N+M. This condition is as shown in Figure 6(a) or Figure 6(b), respectively, when the barcode is within the reading zone.
This corresponds to the fact that N-M, N+M> is not satisfied. In this case, the process jumps to step (13) and starts processing the next barcode i+1.

[0016] Barcode reading zone <N-M, N+
M>, it is determined in step (5) whether bi≦N. If the answer is NO, this indicates that the barcode is to the right of the center line (see Figure 6(c)). At this time, as in step (6), Di = bi
-N.

[0017] If bi ≦N in step (5), then
Proceeding to step (10), it is determined whether ei≧N. If YES, the barcode is placed on the center line (see Figure 6(d)), and this barcode < bi
, ei > is determined as the reading target (step (12)
)).

If ei <N, the barcode is on the left side of the center line (see FIG. 6(e)), and in step (11) Di = N-ei is set. Step (
7) Now, compare Di obtained as above and M, and if Di < M, then in step (8)
and Dmin (in the first case Dmin = M
Therefore, Di<Dmin), Di<Dmin
If so, set Dmin=Di. In this way, the barcode with the smallest distance Di between the barcode and the center is found.

Then, in step (13), i is incremented and the process returns to step (3). Step (
3) Then, perform the above judgment for all barcodes, and if i=n, move to step (15).
Check whether Dmin <M. Dmi
If n = M, it means that there is no barcode covering the reading zone <N-M, N+M> as shown in Figures 6(c) and (e), and barcode reading is given up, resulting in no output. A signal indicating this is issued (step (17)).

If Dmin<M, then FIG. 6(c), (
e) It means that a barcode exists, and the position coordinates <bi,ei> of the barcode are determined and output (step (16)). In the above manner, the barcode covering the reading zone <N-M, N+M> can be identified.

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, in OCR, the scanning range is 2.
It can be easily extended to the case of dimensions. At this time, as the distance between the character strings i, j and the center X of the scanning range, as shown in FIG. 7, the distance Di from the center X to the nearest part,
Dj may be set. However, if you think about it in practice, when reading horizontally written characters, it is clear that when you compare the possibility that the targeted character string will move a distance D above or below from the center with the possibility that it will move a distance D to the left or right. The former is more likely. Conversely, there is a high possibility that character strings that are far to the left or right are unintentionally coming into view. Therefore, when calculating the distance from the center, different weights should be given to the horizontal and vertical components. For example, the distance Di between the center X=<NH,Nv> and the character string i is calculated by using m as the weighting coefficient (0<m<1), Di =
The distance Dj between the center X of m(bvi-Nv) and the character string j is Dj = {m(evj-Nv)2 + (NH -eHj
)2 }1/2 can obtain more desirable results. Here, bvi is the ordinate of the lower end Pi of character string i, evj is the ordinate of the upper right end Pj of character string j, eHj
is the abscissa of the upper right corner Pj of character string j.

Various other design changes can be made without changing the gist of the present invention.

[0023]

As described above, according to the optical reading device of the present invention, if at least a part of the symbol images exists in a certain range at the center of the scanning range, the By recognizing the symbol at the center or the symbol closest to the center of the scanning range, and not recognizing the symbol if the symbol image is not included in a certain range in the center of the scanning range, only the symbol intended by the user is always recognized. can be read. Therefore, the symbol can be read reliably by the optical reading device, and the reading efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a main part of an electric circuit of an optical reading device according to the present invention.

FIG. 2 is a perspective view showing the internal structure of the optical reading device.

FIG. 3 is a diagram showing a scanning range of an optical reading device.

FIG. 4 is a waveform diagram showing a synchronization signal S1 and an image signal S2.

FIG. 5 is a flowchart showing the processing procedure of the symbol image specifying unit 92.

FIG. 6 is a diagram showing the positional relationship between the scanning range of the optical reading device and the barcode image.

FIG. 7 is a diagram showing the positional relationship between a two-dimensional scanning range and a character string.

[Figure 8] BC that reads barcodes attached to multiple products
It is a figure showing R.

[Explanation of symbols]

1 Housing 2 Laser oscillation device 6a, 6b Barcode side 7 Photo receiving element 9a, 9b processing section 12 Light receiving element for scanning detection 91 Symbol position detection section 92 Symbol image identification part 93 Symbol recognition section

Claims (1)

[Claims] 1. An optical reading device that reads a symbol attached to a target surface by applying light output from a light source to the target surface and focusing reflected light from the target surface within a scanning range of a scanner, comprising: symbol position detection means for detecting the position where an image of the symbol obtained by scanning exists within the scanning range; and at least a portion of the symbol image detected by the symbol position detection means within a certain range in the center of the scanning range. If there is a symbol image, the symbol image located at the center of the scanning range or the symbol image closest to the center of the scanning range is identified, and the symbol image detected by the symbol position detection means is located at the center of the scanning range. An optical reading device comprising: symbol image specifying means that does not specify a symbol image if the symbol image does not fall within a certain range; and symbol recognition means that recognizes the content of the symbol specified by the symbol image specifying means.