JPS6231485A - Bar code reader - Google Patents

Abstract

PURPOSE:To obtain a bar code reader which works at a low speed and with high performance by extracting the count output corresponding to the bar code out of a counting circuit in response to the output of detector. CONSTITUTION:Data shift registers 20 and 21 store the data on adjacent bar widths. The output of the register 20 is multiplied by 1/n- and n-multiplying circuits 22 and 23 and also multiplied directly by 1/n, n and 1 and then sent to error detecting circuits 24, 26 and 25 respectively. Then an error is measured between the outputs of both registers 20 and 21. For this error output, an ON signal is stored in a character detection shift register 30 nd the result of measurement of the ratio between the data on the adjacent bar widths is shifted toward a character detection shift register 37. Then the result showing that registers 30-37 are all turned on is delivered through an AND circuit 40 as the bar code detection signal. While black/white width data given from a black/white counter 13 are written alternately on a buffer memory 16. Then the bar code detection signal is received from a bar code detection output circuit 41 and delivered between blanks as a data cover signal through a bar code signal output circuit 17.

Description

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

[Conventional technology]

Conventionally, a stationary barcode is used in which a laser beam or the like passes through a scanning window of a scanner onto the surface of an object on which a barcode exists, and the barcode is read by the light reflected from that surface. Although it is easy for the reading device to read the .-- code, it is difficult to extract only the signal corresponding to the .-- code from the scanning signal. In other words, when a paper surface with a barcode label is scanned with a scanner, electrical signals obtained from the scanner while scanning the barcode, that is, barcode signals, and non-barcodes are separated. The method of extracting only the code signal by distinguishing it from the electrical signal, that is, the noise, obtained when scanning the paper surface is to extract only the code signal that corresponds to the white bar among the white and black bars that make up the bar code. The pulse width of the electrical signal is measured, and if the measured value exceeds a certain value, it is considered the start of barcode scanning, and the subsequently detected margin is considered the end of barcode scanning, and the white bar and black bar between this margin are If this number exceeds a predetermined value, the barcode detection conditions are met, and the electrical signal output from the scanner between the margins is used as a barcode signal.

[Problem that the invention seeks to solve]

However, in such a barcode detection method, the noise may contain many electrical signals that satisfy the barcode detection conditions, so it is difficult to identify only the barcode signal from among the electrical signals output from the scanner. The drawback was that the ability, or pattern extraction rate, was low. Therefore, there is a very high probability that noise will be erroneously output as a barcode signal, so the symbol conversion circuit that sequentially processes barcode signals and converts them into symbols must process a huge amount of data, making it possible to perform instant conversion processing. This had the disadvantage of requiring a very expensive computing unit.

The purpose of the present invention is to provide a high-performance barcode reading device that can accurately extract a barcode signal and reduce the mixing ratio of noise other than the barcode signal, and can therefore use a low-speed and inexpensive arithmetic unit. It's about doing.

[Means for Solving the Problems] The present invention provides a barcode reading device that recognizes a barcode by scanning a surface on which a barcode is displayed, which includes a scanner, and a receiver for receiving the output of the scanner. a counter circuit that counts the pulse width; and a detector that receives the output of the counting circuit and detects the continuity of the rate of change in the width of adjacent white pars and black pars that constitute the barcode; The barcode reading device is characterized in that a counting output corresponding to a barcode is extracted from the output of the counting circuit according to the output of the counting circuit.

〔Example〕

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of a barcode, and FIG. 2 is a diagram showing an embodiment of the present invention. In the embodiment, the scanner 11 scans the bar code surface as shown in FIG. It is stored in the register 20 and buffer memory 16. The data stored in the data shift register 20 is shifted in the direction of the data shift register 21 when changing from a white bar to a black par and from a black par to a white bar. Therefore, adjacent mouth width data and black width data are alternately stored in the data shift registers 20 and 21.

1/n times multiplication circuit 22, n times multiplication circuit 23F! The error detection circuit 24 calculates values of 1/n times and n times the mountain width and black width data output from the data shift register 20,
Output to 25. Here, the barcode is defined by the thin strips and tabs that make up the barcode according to its standards.
zW2sW5jW4xb5 and thick bar W1+b3. The width ratio of b4 is determined, and the error in the width of the thin bar and thick bar due to printing accuracy must be within a certain value according to the standard. In other words, if the thick par is n times the thin par, the thin par will be 1 times the thin par, the thick par will be 1 times the thick par, and the thin par will be 1/n times the thick par, but these n#L1/n The multiplied value remains constant within a certain error range. Also, since the barcode consists of only thin pars and large pars, there are only four types of combinations of adjacent pars: thin par and thin par, thin par and thick bar, thick bar and thin bar, and thick par and thick par. So the ratio is l.

1/n #n #1. According to Figure 1, t)
i r Wi e b 2 mW2hb3 *W5 m
b4 mW4 l b5 indicates one character, in this case it is the symbol °°°gW4
and bs) all correspond to either 1*1/n or n.

Here, the character gap 7°3 in Figure 1 is the white part inserted between the gear rafter and the character, b5
bl , W4 # b2 g −aW4 e b
If 5 is a gear rafter constituting a bar code, the ratio of the adjacent bar widths will all correspond to either Ll/n or n, and 8 pieces will be obtained consecutively. This is bl and Wj l Wl and b2+ ”' 1 W4 and b5
It corresponds to a set of 8. Therefore, in the present invention, the characters constituting the barcode are 6 thin bars and 3 thick bars, and since the ratio of the widths of the thin bars and thick bars is 1:n, the ratio of the widths of adjacent bars is Ll/nun, and using the condition that it occurs eight times in a row, the data in which the ratio of adjacent bar widths is within a certain value considering printing errors are continuous between one margin in Figure 1. The detection condition for the bar code pattern is that 9 pieces are detected, and when these conditions are met, the electric signal output from the scanner 11 is detected.
Output as a code signal.

In the present invention, in order to check the above-mentioned conditions, data of adjacent bar widths are stored in data shift registers 20 and 21, and the output of data shift register 20 is multiplied by 1/n in a 1/n multiplication circuit 22. The error detection circuit 24 outputs the same value to the error detection circuit 25, the n-fold multiplication circuit 23 multiplies it by n, and outputs it to the error detection circuit 26. In other words, the error detection circuit 24 receives 171 times the data of the data shift register 20, the error detection circuit 25 receives 1 times the data, and the error detection circuit 26 receives n times the data.
The error with the output from the data/futreno star 21 is measured by error detection circuits 24, 25, and 26. Here, if a thin bar with a fortune of 1 is stored in the data shift register 20 and a thick bar with a width of n is stored in the data shift register 21, then the error detection circuit 24 receives 1/n and n1.
l and n to the error detection circuit 25; n to the error detection circuit 26;
and n are input, and the error detection circuit 26 assumes that the input data are n and n and there is no error, and turns on its output, but in reality, it is allowed by the G-code standard. If the value is within a value that takes into account printing errors, the output is turned on. At this time, the outputs of the error detection circuits 24 and 25 are turned off, but the output of the error detection circuit 26 is turned on, so the OR circuit 2
The output of 7 is turned on, and when the next par width data is input to the data shift register 20 in synchronization with the change from a white bar to a black par or from a black bar to a white par, the output is turned on in the trap character detection shift register 30 at the same time. The signal is stored. Tsumashi Data Shift Renoster-20, 21
The ratio of the width data of adjacent bars stored in is 1.1
/n, if n, character-detection shift register-3
An on signal is stored at 0, the ratio of adjacent bar width data sequentially output from the black and white counter is measured, and the result is shifted in the direction of the character detection shift register 37.

AND circuit 40 is character detection shift register 3
The output is turned on only when all of the signals from 0 to 37 are turned on. Character detection shift registers 30 to 37 are all turned on when nine pieces of bar width data are consecutively detected in which the ratio of adjacent bar width data is within a certain standard value considering printing errors. , AND circuit 40
A barcode detection signal is outputted to an external device from the barcode detection signal output circuit 41 which receives the output of the barcode detection signal output circuit 41 .

On the other hand, the white and black width data constituting the character output from the white and black width counter 13 is stored in the graph memory 1.
6 and is sent to the margin detection circuit 12. The margin detection circuit 12 clears the buffer memory address counter 15 when a white margin 1 on the left side of FIG. 1 is detected as having a certain length. After that, buffer memo of black and white width data alternately! If the barcode detection signal is output from the barcode detection signal output circuit 41 before the next blank space (margin 1 on the right side in FIG. 1) is detected, the buffer memory 16 is The data written in the blank space is treated as a cover code signal and output to an external device via the barcode signal output circuit 17.If a barcode detection signal is not output between the margins, the panther memory address counter 15 is cleared. Repeat the above operation again.

As mentioned above, the electrical signals output from the scanner 11 include many electrical signals whose number of pulses is equal to or greater than a certain value, which corresponds to the white and black parts output between the margins, and these conditions are sufficient. However, in the present invention, by adding the condition that there are 9 consecutive pieces of data in which the ratio of adjacent bar widths is within a certain value, the pattern detection rate is significantly improved. When scanning something other than a code, the electrical signal of the scanner will not be erroneously output as a barcode. This is because numbers, alphabets, hiragana, kanji, and various patterns are printed on the paper surface on which the barcode exists, but it is almost impossible for these to satisfy the pattern detection conditions of the present invention.

In addition, in this embodiment, considering the case where the blank space cannot be detected due to dirt on the barcode label, etc., instead of outputting the data between the blank spaces to the outside as a barcode signal, the above-mentioned nine continuous data and their A certain number of data input before and after may be output as a barcode signal. Further, nine consecutive pieces of data may be used as arbitrary consecutive data in accordance with various barcodes. Furthermore, in the present invention, the data between the margins is output as a barcode signal to an external device, but the output from the barcode detection signal output circuit 41 in FIG. Since the barcode is turned on and the location of the barcode can be determined, it may be used as a barcode area detection device.

〔Effect of the invention〕

In the present invention, with the configuration described above, the scanner 1
It detects only the electrical signals scanned on the barcode from among the electrical signals output from the device, and it is very easy to implement, and the number of components is smaller than that of conventional devices of this type.・High mother turn detection rate. That is, according to the present invention, due to the high turn detection rate, the symbol conversion device does not need to process a huge amount of data, and an inexpensive arithmetic unit can be used, resulting in a significant cost reduction. It has practical effects.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a typical barcode, and FIG. 2 is a configuration diagram showing an embodiment of the present invention. 11...Scanner, 12...Margin detection circuit, 13...
・White, black width counter, 14... White, black change detection circuit, 15... Buffer memory address counter,
16... Buffer memory, 17... Bar code signal output circuit, 20.21... Data shift register, 22... 1/n times multiplication circuit, 23... n times multiplication circuit, 24...・Error detection circuit (IL25...Error detection circuit (I[L26...Error detection circuit (l[), 2
7...OR circuit, 30-37...Character detection shift register, 40...AND circuit, 41...
Barcode detection signal output circuit.

Claims (1)

[Claims] (1) A barcode reading device that performs barcode recognition by scanning a surface on which a barcode is displayed includes a scanner, a counting circuit that receives the output of the scanner and counts pulse widths, and a a detector that receives the output and detects the continuity of the rate of change in the width of adjacent white bars and black bars constituting the bar code; A barcode reading device characterized by extracting count output corresponding to a code.