JP3064632B2 - Barcode reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader for reading a bar code, and more particularly, to prevention of double reading. In the present specification, the term “double reading” is used to read (decode) the contents of a barcode and continuously image and decode the barcode for which data transfer to the host has been completed. To the host.

[0002]

2. Description of the Related Art In recent years, point of sales (POS)
With the spread of the system, barcodes have become ubiquitous. This barcode has dozens of types of code systems.
de39, ITF, etc. These barcode systems are called one-dimensional barcodes, and the allowable information amount is about a dozen characters.

[0003] On the other hand, POS systems are widely used at merchandise sales sites such as department stores and supermarkets, and barcode readers are used as terminals thereof. Therefore, the bar code reader is required to be inexpensive, easy to use, and accurate in reading the bar code.

[0004] In addition, one-dimensional bar code readers, in particular,
In the case of a type that constantly scans a barcode, even if the barcode reading device finishes reading the barcode, the item with the barcode may be left as it is, or even if the user tries to remove the item, the barcode may be slowly removed. When the removal operation is performed, the same barcode is read multiple times, or the barcode cannot be read, so while moving the item from one place to another, it is read multiple times and the number of items actually purchased There may be a discrepancy between the number read and the number transferred to the host.

Therefore, in the conventional one-dimensional bar code reader, if the contents of the bar codes read continuously are the same, it is determined that one label has been read twice.
A method of preventing double reading by invalidating a bar code read later has been proposed.

[0006]

However, in recent years, the shortage of information amount of one-dimensional barcode has been overlooked.
Several code systems having a large amount of information called two-dimensional barcodes have been developed. One of them is called a data code. This data code is formed of a two-dimensional black and white pattern, and is a square pattern as a whole including an L-shaped outer frame, an alternately black and white outer frame, and a data area therein.

However, in a two-dimensional bar code reader for reading such a two-dimensional bar code, no effective double reading prevention method has been proposed yet.

If the above-described method for preventing double-reading of a one-dimensional bar code is applied to this type of two-dimensional bar code reading apparatus, the two-dimensional bar code has an information amount smaller than that of the one-dimensional bar code. And the data comparison process takes a long time. Further, the decoding process of the two-dimensional barcode itself is very complicated and time-consuming. Therefore, the conventional method of comparing the decoding contents has a problem that the processing time is long,
It cannot be directly applied to a two-dimensional barcode reader.
The present invention has been made in view of the above points, and an object of the present invention is to provide a barcode reader that can prevent double reading with simple and high-speed processing.

[0009]

In order to achieve the above object, a bar code reader according to the present invention is provided with an image storage device for storing image information obtained by imaging a bar code at a predetermined time interval. Means, position detecting means for detecting position information of a barcode from image information stored in the imaging storage means, first storage means for storing position information of the barcode detected by the position detecting means, Second storage means for storing the position information of the barcode detected immediately before by the position detection means, comparison means for comparing the two position information stored in the first and second storage means, And decoding means for decoding the contents of a bar code from the image information stored in the imaging storage means when it is determined that the two pieces of position information are different as a result of the comparison by the comparison means. It is characterized by a door.

[0010]

That is, in the bar code reader according to the present invention,
Comparing means for comparing the position information of the bar code detected by the position detecting means stored in the first storage means with the position information of the bar code previously detected by the position detecting means stored in the second storage means; When these two pieces of position information are different, the decoding means decodes the contents of the barcode from the image information stored in the imaging storage means.

That is, first and second storage means for storing the position information of the barcode and comparison means for comparing the two pieces of position information are provided, and the position of the decoded barcode and the newly read barcode position are provided. Compare with the barcode position,
If they are the same, the newly read barcode label is invalidated, and decoding is not performed, thereby preventing double reading.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram of a first embodiment of the present invention. In the same figure, the CCD image sensor 1
Captures image information of a barcode label which is affixed to an item (not shown) and printed with a barcode. The frame memory 2 temporarily stores image information captured by the CCD image sensor 1.

The label detection processing unit 3 includes a frame memory 2
The barcode label is found from the data stored in the storage device, and its position information is output. The primary buffer 4 sequentially stores the position information of the barcode labels detected by the label detection processing unit 3 and transfers the stored label position information to the secondary buffer 5 or the comparison unit 6. 2
The next buffer 5 stores the label position information sent from the primary buffer 4 and transfers the stored label position information to the comparing unit 6. The comparing unit 6 compares two pieces of label position information sent from the primary and secondary buffers 4 and 5.

The decoding processing section 7 reads out the bar code label data from the data stored in the frame memory 2 based on the bar code label position information detected by the label detection processing section 3, and reads the bar code label data. The content is decoded, and the decoding result is transferred to a host or the like (not shown).

The control unit 8 controls the CCD image sensor 1, the label detection processing unit 3, the primary buffer 4, the secondary buffer 5, the comparison unit 6, the decoding processing unit 7, and the like. The label detection processing unit 3, the comparison unit 6, the decoding processing unit 7, and the control unit 8 can be configured by a CPU 9.

Next, a processing procedure when a bar code label is read in the above-described configuration using a previously published data code as an example will be described with reference to the processing flowchart of FIG.

According to the control of the control unit 8, first, image information of a bar code label is picked up by the CCD image sensor 1 and stored in the frame memory 2 (step S1).
A bar code label is detected by the label detection processing unit 3 (step S2). That is, in the case of a data code label, since a characteristic pattern exists in the L-shaped outer frame, the coordinates of the four corners can be found by detecting this pattern. Then, it is determined whether there is a barcode label, that is, whether the coordinates of the four corners have been obtained (step S3). If the barcode label does not exist in the captured image, the process returns to step S1.

Here, the detection of the bar code label and the determination of the presence or absence of the label in the above steps S2 and S3 will be described in more detail with reference to the flowcharts of FIGS.

The label detection processing section 3 scans the frame memory 2 every several pixels in the horizontal direction (x), for example, as shown in FIG. That is, first, the Y coordinate is set to the initial value Y _0.
To initially set (step S21), and by changing the number of pixels every other X-coordinate to the initial value X ₀ ~ maximum X _N, scanning in the horizontal direction (step S22). Then, the coordinate points of the black level detected first and the black level detected last in the scan are stored (step S23). Then, to update the Y-coordinate by a predetermined distance A (step S24), and the result determines whether exceeds the maximum value Y _N (step S25). If not, the process returns to step S22, and the above processing is repeated.

When all the horizontal scans have been completed, the first detected black level coordinate points are connected, and a straight line A connecting many coordinate points (for example, four or more) is connected.
(Eg, L _{1 in} FIG. 6), and if there is such a straight line A (step S26), all the coordinate points PA on the straight line _A are stored (step S27). Similarly, a line B connecting the coordinate points of the black level detected last is searched for a straight line B connecting many coordinate points (for example, four or more). If there is such a straight line B (step S28), the straight line B is searched. All coordinate points P _B on _B are stored (step S29).
Then, it is determined whether or not the straight lines A and B are substantially orthogonal (step S30). If the straight lines A and B are orthogonal, both straight lines A. and B are determined from the stored coordinate points P _A and P _B. The coordinates of the intersection b of B (see FIG. 6) are obtained by calculation (step S31).

On the other hand, in step S30, a straight line A,
If it is determined that B is not substantially orthogonal (including the case where the two straight lines A and B cannot be obtained), scanning is further performed in the vertical direction (y), and similar processing is performed. That is, first, the X coordinate is initialized to the initial value X ₀ (step S3).
2) by changing every several pixels the Y coordinate to the initial value Y ₀ ~ maximum Y _N, scanning in the vertical direction (step S33). Then, the coordinate points of the black level detected first and the black level detected last in the scan are stored (step S34). Then, to update the X-coordinate by a predetermined distance B (step S35), the result is determined whether it exceeds the maximum value X _N (step S3
6). If not, the process returns to step S33,
The above process is repeated. When all the scans in the vertical direction have been completed in this way, a straight line C connecting the first detected black level coordinates and connecting many coordinate points (for example, four or more) is searched for. If there is (step S37), all the coordinate points PC on the straight line _C are stored (step S38). Similarly, a straight line D (for example, L _{2 in} FIG. 6) connecting the coordinates of the last detected black level and connecting many coordinate points (for example, four or more) is searched for. If there is (step S39), all coordinate points PD on the straight line _D are stored (step S4).
0). Then, it is determined whether or not there are two straight lines that are substantially orthogonal to each other with respect to the straight lines A to D (step S41).
42), the process ends, and the process returns to step S1.

Also, if there are two lines that are substantially orthogonal,
The coordinates of the intersection b (see FIG. 6) of the two straight lines are calculated from the coordinate points stored for the two orthogonal straight lines (step S43).

The coordinates a, b, c, d of the four corners of the label are calculated from the calculated intersection point b of the two straight lines and the detected coordinate point.
To determine. That is, data is read out by scanning in a direction away from the intersection b along each of two orthogonal straight lines to read data (step S44), and the last coordinate point of the black level is set to the point a.
And c (step S45). The coordinates of the point d are calculated from the stored coordinates of the three points a, b, and c and the result is stored, and the obtained coordinates of the four corner coordinate points a, b, c, and d are represented by position information. Is output to the primary buffer 4 (step S46). That is, in the case of the data code, since the label is a square, the intersection b
If you know the length of one side, you can easily determine the four corners. Note that the coordinates of the four corners do not need to exactly match the label positions.

The coordinates of the four corners thus found are temporarily stored in the primary buffer 4, and are stored in the primary buffer 4.
Transfers the position information to the comparison unit 6 and the secondary buffer 5.
The secondary buffer 5 transfers the stored position information to the comparing unit 6 and stores the position information of the label sent from the primary buffer 4. Then, the comparing unit 6 compares at least one coordinate point of the two sets of four coordinates sent from the primary buffer 4 and the secondary buffer 5 to determine whether they are the same (step S4). In this determination, if the error of each coordinate point is about several pixels, it is regarded as the same. Here, if it is determined that the positions are the same, it is determined that the same barcode label has been read twice, this label is invalidated, and an alarm indicating that the double reading prevention mechanism has been activated is issued. After prompting replacement of the barcode label, that is, replacement of the product (step S5), the process returns to step S1 to perform the next reading.

If it is determined in step S4 that the positions are different, a process for determining the position of the barcode label (a process for confirming the stillness of the barcode label) is performed. That is, the label is immediately read again (step S6), and the label detection processing unit 3 is read in the same manner as in step S2.
To detect the label position (step S7). And
The new position information is stored in the primary buffer 4, and the position information of the immediately preceding label stored in the secondary buffer 5 is compared with the coordinates by the comparing unit 6 (step S8). This time, if the positions are the same, it is considered that the barcode label has been determined.

If the position of the bar code label is determined in this way, that is, if the stillness is confirmed, the bar code label is decoded by the decoding processing section 7 (step S9). Using the label position information from the label detection processing unit 3, the decoding processing unit 7 scans only the frame memory 2 where the bar code label is present along the bar code label as shown in FIG. Decoding information. Then, the decoding result is transferred to the host (not shown) (step S10), an alarm for notifying that the reading of one barcode label has been completed is issued (step S11), and the process is terminated. The process returns to S1 to read the next barcode label.

On the other hand, if it is determined in step S8 that the position is different, it is determined that the barcode label is moving, and it is determined that label replacement is in progress, and decoding is not performed. Return to the next reading.

That is, in the first embodiment, as soon as the bar code label is replaced and the image is picked up by the CCD image sensor 1, the image is picked up again by the CCD image sensor 1, and if the label position has not moved, decoding is started. I do. Until the decoded label is replaced, the loop of steps S1 to S5 is repeated, and decoding is performed again, that is, double reading is prevented.

If an image is taken while the label is being moved to remove the decoded bar code label, the process goes from step S4 to step S6. In this case, the stillness is confirmed in step S8. Since the data is rejected and returned to step S1, decoding is performed again, that is, double reading is prevented.

During the insertion of the next barcode label, the stillness check in step S8 is rejected, and the decoding is not started until the barcode label becomes still.

However, in this case, if the bar code label is stopped in the time between the step S8 based on the label reading in the step S6 and the label reading in the step S1, the process proceeds to the step S4. Since it is determined that the positions are the same, it is not possible to proceed to the processing after step S6, and there is a possibility that decoding will not be performed forever. However, in such a case, it is possible to cope with the alarm in step S5 by notifying the operator that reading is not possible and prompting the movement of the barcode label.

As described above, in the first embodiment, since only the position information of the barcode label is compared, the comparison process can be easily and quickly performed. In addition, since decoding is performed after the position of the barcode label is determined, double reading during barcode label replacement can be prevented.

(Second Embodiment) In the first embodiment, the label reading in step S6 is performed immediately. However, if it is performed after one or two seconds, for example, the label can be set securely. Since it can be confirmed that reading has been performed, reading can be performed more accurately.

(Third Embodiment) In the second embodiment, if it is considered that another barcode is always read if the label reading in step S6 is performed after one or two seconds, the label position in step S8 is considered. The comparison process can be omitted. In this way, higher-speed processing can be performed.

(Fourth Embodiment) In the first embodiment, after the alarm is generated in step S11, the process immediately returns to step S1 to perform the label reading process. Is sufficient, for example, after a few seconds, the label is read in step S1.
8 can be omitted, and higher-speed processing can be performed. Similarly, in the second and third embodiments, when returning from step S11 to step S1, a time interval in which a person can sufficiently exchange labels may be set. Also, when returning from step S5 to step S1, it is preferable to similarly wait for a time interval at which a person can sufficiently exchange labels.

In the first to fourth embodiments, the data code is used for the bar code label. However, the present invention is not limited to this. For example, PDF417, Code49,
For example, another two-dimensional barcode may be used. Further, the label position information may be one, two, or three of the four coordinates of the four corners of the label. Further, in the above embodiment, the CCD image sensor 1 and the frame memory 2
CMD (Charge Modulation Device) that allows random access as an image sensor
If you use, since it has the function of frame memory,
There is no need to provide a separate frame memory.

[0037]

As described in detail above, according to the present invention,
A bar code reader that can prevent double reading with simple and high-speed processing can be provided. That is, since only the position information of the barcode label is compared, double reading of the two-dimensional barcode can be prevented at high speed and easily.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the first embodiment.

FIG. 3A is a first part of a series of three flowcharts for explaining the label detection process in the flowchart of FIG. 2 in more detail, and FIG. 3B is a second part of the flowchart. Part.

FIG. 4 is a third part of a series of flowcharts for explaining the label detection processing in the flowchart of FIG. 2 in more detail;

FIG. 5 is a diagram showing scanning directions and detection coordinate points for obtaining four corners.

FIG. 6 is a diagram showing a relationship between two substantially orthogonal straight lines obtained from detected coordinate points and coordinate points at four corners.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... CCD, 2 ... Frame memory, 3 ... Label detection processing part, 4 ... Primary buffer, 5 ... Second buffer, 6 ... Comparing part, 7 ... Decoding processing part, 8 ... Control part, 9 ... CPU.

Claims (1)

(57) [Claims] 1. An imaging storage means for storing image information obtained by imaging a barcode at predetermined time intervals, and detecting barcode position information from the image information stored in the imaging storage means. Position detection means; first storage means for storing position information of the barcode detected by the position detection means; second storage for storing position information of the barcode detected immediately before by the position detection means Means for comparing two pieces of position information stored in the first and second storage means; and as a result of the comparison by the comparing means, when it is determined that the two pieces of position information are different, Decoding means for decoding the contents of the barcode from the image information stored in the imaging storage means.