JP2689158B2 - Barcode reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a bar code reading device, particularly when a bar card (a card on which a bar code is printed) or the like has wrinkles or folds, or a bar card is fed. The present invention relates to a bar code reading device that can correctly read a bar code even when unevenness occurs.

[Conventional technology]

Bar codes have been used in various fields. In addition to POS (point-of-sale information management), technologies have been developed that allow users to make calls by simply inserting a business card with a barcode printed into the phone.

When used and applied in various fields like this, the paper on which the barcode is printed is also used from hard to soft, and when reading the barcode, various misreading factors cause the barcode to be printed. There is also a case where it occurs on the side of the paper. For example, when the paper is soft, wrinkles and folds occur in the bar code portion, which may cause misreading when reading the bar code.

A conventional bar code reader has a structure as shown in FIG. That is, the bar code read by the bar code reading unit 1 is converted from an optical signal into an electric signal, and is compared with the slice level L set by the binarizing means 2 to perform binarization of black and white and waveform. The shaping is performed, and the time width detection means 3 converts the black and white binarized shaping waveform into the time width. Then, the thinness determination means 4 compares the time width with a determination reference time width of a constant time width for determining the thinness or thickness of black and white, determines the thinness of black and white, and sends it to the analysis means 5, and the analysis means. In 5, the code of the combination of the thin black bar, the thick black bar, the thin white space, and the thick white space sent from the thin judgment means 4 is analyzed.

[Problems to be solved by the invention]

However, in the conventional bar code reading apparatus having the structure as shown in FIG. 7, the thin width determining unit 4 determines the time width detected by the time width detecting unit 3 and the determination reference time width of the constant time width T. Since the configurations are compared, there is a drawback that the barcode reading unit 1 side erroneously reads as a deviation from the normal state.

For example, when the bar code read by the bar code reader 1 has wrinkles or folds, the waveform read by the bar code reader 1 is corrugated as shown in FIG. Since the binarization is performed in step 1, the binarized waveform is not shaped in the correct time width in the normal state. Therefore, the thick / thin determination means 4 determines that the thick one is originally thin, or vice versa. However, there is a defect that the object is judged to be thick and is misread.

Further, if unevenness in the feeding of the bar card on which the bar code is printed occurs, the thinness is judged to be thick if the feeding of the bar card is delayed as shown in FIG. 9, or the feeding of the bar card is not shown as shown in FIG. There is a drawback that the thickness is finely judged when the speed is high.

An object of the present invention is to solve the above-mentioned drawbacks by always changing the judgment reference time width of the constant time width T according to the value read by the barcode reading unit side. SUMMARY OF THE INVENTION An object of the present invention is to provide a bar code reader capable of always reading accurately and stably even if a bar card on which a bar code is printed is wrinkled or bent, or the bar card is unevenly fed.

[Means for solving the problem]

In order to achieve the above-mentioned object, a bar code reading device of the present invention is a binarization part for reading a bar code and a binarization for binarizing an output read by the bar code reading part into a black and white shaped waveform. Means, a time width detecting means for detecting the time width from the waveform binarized by the binarizing means, and a criterion for judging the time width and the thinness detected by the time width detecting means. The thinness determining means for determining the fineness from the time width and the thinness obtained from the time width detecting means are the difference between the thickness detection time width and the immediately preceding thin or thick time width. By multiplying by a predetermined coefficient, a judgment reference time width correction means for calculating a correction value for the judgment reference time width, and a correction value calculated by the judgment reference time width correction means is added to the judgment reference time width, When a new judgment criterion is used as a judgment criterion for thinness by the thinness judgment means. It comprises a reference time width generating means for generating a width, and an analysis means for decoding the bar code from the HosoFutoshi code black and white, which is determined by the HosoFutoshi determining means.

An embodiment of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 1 is a basic configuration diagram of a bar code reading device according to the present invention, FIG. 2 is an example configuration of a bar code reading device according to the present invention, and FIG. 3 is a judgment reference time width when a bar card has wrinkles. Shows an example of tracking the detection time width, FIG. 4 is a variable explanatory view of the judgment reference time width when the bar card feeding is slow, and FIG. 5 is a judgment reference time when the bar card feeding is fast. Width variable explanatory diagram, FIG. 6 (I), (II)
Shows an example of the follow-up experiment of the judgment reference time width of the black bar and the white space when the bar card has wrinkles.

In the basic configuration diagram of the bar code reading apparatus according to the present invention in FIG. 1, 1 to 5 correspond to those in FIG. 7, 6 is a judgment reference time width correcting means, and 7 is a judgment reference time width creating means. ing.

The judgment reference time width correction means 6 detects the thin or thick detection time width of the black bar or white space detected by the time width detection means 3 and the thin or thick detection time width of the immediately preceding black bar or white space. If the thick detection time width, that is, the detection time width detected by the time width detection means 3 is, for example, a thin black bar, the detection time width of the preceding thin black bar, or 1 if the white space is thin It compares the detection time width of the previous white space, finds the time width difference, and outputs the value obtained by multiplying the time width difference by a certain coefficient as a correction value for the judgment reference time width. It is supposed to do. The constant coefficient is determined by the transportation speed of the bar card.

The determination reference time width creating means 7 creates the determination reference time width in the thin weight determining means 4, and the initial value set from the outside becomes the determination reference time width in the first thin weight determination. From then on, the value obtained by accumulating the correction value output from the judgment reference time width correction means 6 to the initial value becomes the judgment reference time width. That is, the determination reference time width changes in accordance with the change in the detection time width that is thick if it is thick or thin if it is detected by the time width detection means 3.

Next, the operation of FIG. 1 will be described. The bar code reading section 1, the binarizing means 2 and the time width detecting means 3 are the same as those of the conventional bar code reading apparatus shown in FIG. The time width detecting means 3 outputs the detection time width obtained by converting the waveform width of the binarized shaped waveform into the time width, that is, the time width of the black bar and the white space read by the bar code reading unit 1 is alternately output. come. Now, for example, a black bar will be described. The detection time width of the black bar output from the time width detection means 3 is input to the thin weight determination means 4 and the thin weight determination means 4
As described below, it is compared with the determination reference time width of the black bar created by the determination reference time width creating means 7, and the thinness thereof is determined. Then, the judgment result is sent to the analysis means 5 and held as decoding data.

On the other hand, the black bar detection time width output from the time width detection means 3 is simultaneously input to the judgment reference time width correction means 6 and based on the thin or thick information judged by the thin judgment means 4. It is compared with the immediately preceding corresponding thin or thick detection time width. From this comparison, the difference in the time width between the two is obtained, and the value obtained by multiplying the difference in the time width by a certain coefficient is used as the correction value from the judgment reference time width correcting means 6 to the judgment reference time width creating means. It is output to 7. The judgment reference time width creating means 7 adds the correction value input from the judgment reference time width correcting means 6 and the previous judgment reference time width to create a new judgment reference time width. This newly created determination reference time width is sent to the thin weight determination means 4 and serves as a reference for the thin weight determination for the detection time width of the next black bar input from the time width detection means 3.

The above has described the correction value by the judgment reference time width correction unit 6 and the creation of the judgment reference time width by the judgment reference time width creation unit 7 for the black bar. Then, the judgment reference time width is created. Therefore, the thin judgment means 4 judges the thinness of the white space on the basis of the newly created judgment reference time width.

In this way, the judgment reference time width serving as the reference for the thin and thick judgment is changed according to the reading waveform read by the barcode reading unit 1, that is, according to the detection time width output from the time width detecting means 3. As shown in FIGS. 8 to 10, when the reading waveform read by the barcode reading unit 1 tends to expand, the judgment reference time width becomes longer,
On the contrary, when the read waveform tends to shrink, the judgment reference time width becomes short and the bar code is read correctly.

FIG. 2 shows the construction of an embodiment of the bar code reading apparatus according to the present invention, and 1 corresponds to that of FIG.
8 is a binarization circuit, 9 is an oscillator, 10 is a counter, 11 is a memory, 12 is a black bar thin detection circuit, 13 is a white space thin detection circuit, 14 is a register, 15 is a decoder, 16 is a subtractor , 17 is a multiplier, 18 is an accumulator, 19 is a comparator, 20 is a subtractor, 21 is a multiplier, 22 is an accumulator, and 23 is a comparator.

When a barcode printed with a barcode is sent to the barcode reading unit 1 of the barcode reading device, the barcode is scanned and read by the barcode reading unit 1. A light / dark optical signal related to the combination of the thin black bar and the thin white space of the barcode read by the barcode reading unit 1 is converted into an electric signal as a read waveform, and 2
It is sent to the digitization circuit 8. The binarization circuit 8 uses a predetermined slice level L based on the read waveform converted into an electric signal.
The black and white binarization and waveform shaping are performed. The counter 10 counts oscillation pulses from the oscillator 9 using the binarized black and white shaped waveform as a gate. The count value counted by the counter 10 indicates the time width for the black and white of the read waveform read by the barcode reading unit 1.
Now, assuming that the counter 10 counts the time width of the waveform of the black bar, the count value of the counter 10 is stored in the memory 11 and is also input to the subtracter 16 of the black bar thin detection circuit 12. It This count value stored in the memory 11 is immediately read out from the memory 11 and the comparator 19
And is compared with the value of the judgment reference time width which has already been input from the accumulator 18 and serves as the judgment reference for the thin weight. The thinness of the black bar is determined based on the magnitude of the count value from the counter 10 and the value of the determination reference time width, and the determination result is stored in the register 14. Further, this determination result is sent to the memory 11, and the count value for the waveform of the black bar corresponding to the previous determination result is read from the memory 11. That is, when the determination result stored in the register 14 is, for example, fine, the count value of the thin black bar immediately before the currently determined thin black bar is read from the memory 11. The previous count value of the corresponding waveform read from the memory 11 is sent to the subtracter 16 and its difference from the count value from the counter 10 already input to the subtracter 16 is subtracted. Desired. The value of the difference between the two obtained by the subtracter 16 is multiplied by a predetermined coefficient in the multiplier 17, and output from the multiplier 17 as a correction value. This correction value is input to the accumulator 18, is added to the value of the judgment reference time width used as the thin judgment reference, and is a new judgment reference time width for the next black bar count value output from the counter 10. Becomes the value of. That is, the reference value of the new determination reference time width is created in the accumulator 18.

Next, since the counter 10 outputs a count value for the waveform of the white space, the count value is stored in the memory 11 and also input to the white space thin / thick detection circuit 13. The white space thin line detection circuit 13 performs exactly the same operation as the black bar thin line detection circuit 12 described above, and the judgment result is stored in the register 14 and the accumulator is also stored.
In 22, a reference value of a new determination reference time width for the count value of the next white space output from the counter 10 is created.

In this way, the black bar thin line detection circuit 12 and the white space thin line detection circuit 13 alternately detect the thin lines of the black bar and white space based on the count value output from the counter 10, and the result is It is stored in the register 14. Decoder 15 is register 14
From the combination of the black bar and the thin space of the white space,
For example, even if the bar card has wrinkles or folds, or if the bar card has uneven feeding, it can be correctly decoded.

For each count value of the first black bar and white space output from the counter 10, the black bar thin and thick detection circuit
It goes without saying that the initial values set in the accumulators 18 and 22 of 12 and the thin white space detection circuit 13 become the reference value of the determination reference time width. These initial values and the coefficients used in the multipliers 17 and 21 are determined based on the experimental results in consideration of the bar card transportation speed.

Further, except for the bar code reading unit 1 and the memory 11, it can be processed by a program by a microprocessor, and when the operation of the microprocessor is fast, the count value output from the counter 10 is stored in the memory 11 and the comparators are directly connected. You may make it input to 19,23 and perform real-time processing.

FIGS. 6 (I) and (II) show an example of the follow-up experiment of the judgment reference time width of the black bar and the white space when the bar card has wrinkles, and FIG. 6 (I) shows the black bar, (II). )
Is for white space. In the accumulator 18 of the black bar thin / thick detection circuit 12, the value of the point A in FIG. 9 (I) is set as an initial value and becomes the first reference value of the judgment reference time width. Similarly, the accumulator 22 of the white space thin detection circuit 13 has the same (II) in FIG.
The value of point B is set as an initial value and becomes the first reference value of the determination reference time width. Also, 1/2 is used as the multiplication coefficient of each of the multipliers 17 and 21, and the value obtained by rounding down the decimal point of the multiplication result is used as the correction value.

It can be seen from FIGS. 6 (I) and (II) that the values X and Y of the respective judgment reference time widths are changed in accordance with the count value C of each thin black bar and the count value D of each thick space. I understand. In the figure, the black circle marks represent the thin or thick read at that time, and the triangular marks A and B represent the initial values.

〔The invention's effect〕

As described above, according to the present invention, the judgment reference time width changes when the bar card has wrinkles, folds or the like, or when the bar card is unevenly fed, so that stable bar code reading demodulation is possible. Therefore, the misreading of the barcode reading measure is reduced.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a bar code reading device according to the present invention, FIG. 2 is an example configuration of a bar code reading device according to the present invention, and FIG. 3 is a judgment reference time width when a bar card has wrinkles. Shows an example of tracking the detection time width, FIG. 4 is a variable explanatory view of the judgment reference time width when the bar card feeding is slow, and FIG. 5 is a judgment reference time when the bar card feeding is fast. Width variable explanatory diagram, FIG. 6 (I), (II)
Is an example of an experiment for following the judgment reference time width of a black bar and a white space when the bar card has wrinkles. Fig. 7 is a block diagram of a conventional bar code reader, and Fig. 8 is a conventional method when the bar card has wrinkles. Fig. 9 is an explanatory view of the occurrence of misreading of a bar card, and Fig. 9 is an explanatory diagram of a conventional misreading when the bar card is fed slowly. FIG. 8 is a diagram for explaining a conventional erroneous reading occurrence when the speed becomes faster. In the figure, 1 is a bar code reading unit, 2 is a binarization unit, 3 is a time width detection unit, 4 is a thinness judgment unit, 5 is an analysis unit, 6 is a judgment reference time width correction unit, and 7 is a judgment reference time. Width creating means, 8 binarization circuit, 9 oscillator, 10 counter, 11 memory, 12 black bar thin detection circuit, 13 white space thin detection circuit, 14 register, 15 decoder, 16 is a subtractor, 17
Is a multiplier, 18 is an accumulator, 19 is a comparator, 20 is a subtractor, 21 is a multiplier, 22 is an accumulator, and 23 is a comparator.

Claims (1)

(57) [Claims] 1. A bar code reading unit (1) for reading a bar code, a binarizing unit (2) for binarizing an output read by the bar code reading unit into a black and white shaped waveform, and the binary value. A time width detecting means (3) for detecting the time width from the binarized waveform by the digitizing means, and a time width detected by the time width detecting means and a judgment reference time width which is a reference for judging thinness. A thinness determining means (4) for determining the thinness, and a predetermined difference between the detection time width of the thinness or the thickness obtained from the time width detecting means and the corresponding time width of the thinness or the thickness immediately before that. And a correction value calculated by the judgment reference time width correction means (6) for calculating a correction value for the judgment reference time width and adding the correction value calculated by the judgment reference time width correction means to the judgment reference time width. Then, the thinness determination means creates a new determination reference time width as a thinness determination reference. A bar code reading device comprising: a judgment reference time width creating means (7); and an analyzing means (5) for decoding the bar code from the black and white thin code judged by the thin judgment means. apparatus.