JPH05298472A - Bar code reader - Google Patents

Abstract

PURPOSE:To improve reliability by reducing the erroneous reading ratio of a left side character so as to reduce the erroneous reading ratio of a whole in a reader where division-reading is executed to a bar code at every right and left side. CONSTITUTION:The deciphered result of the character is read in a buffer BUF, the left side character is judged when whole parity arrayals are not even parities and the right side parity is judged in the case of the even parities. When the fetched left characters are same till a counter LCT counts to three, the left side characters are judged to be the normal left characters. When the fetched right characters are same till the counter RCT counts to two, the right characters are judged to be the normal right characters. Then, the both characters are judged to be the normal characters so that an output to a hostcomputer is executed.

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 having character codes on the left and right.

[0002]

2. Description of the Related Art Generally called source marking,
The JAN code and UPC, WPC, etc. of the system equivalent to this are widely used for the bar code printed on the product, and the standard version has 13 digits and the shortened version has 8 digits. Exists.

JA with a standard version consisting of 13 digits
For example, as shown in FIG. 3, the N-code has two bars having equal widths on both ends of the bar code, left and right guard bars consisting of one space, and three bar codes at the center of the bar code.
A book bar space and a center bar composed of two bars are arranged, and six-digit numbers are encoded between the left guard bar and the center bar and between the center bar and the right guard bar.

Each of the left and right 6-digit numbers is encoded with two bars and two spaces, and if one bar width of the guard bar or center bar is one module, one character, that is, two The total bar width of the black and white pair is coded to be 7 modules.

Regarding encoding, the left data character on the left side of the center bar is an encoding method of an odd parity configuration in which the total bar width in the character is an odd module, and an encoding method of an even parity configuration in which the total bar width is an even module. 2 types of bar configurations are possible, for example, the numeral 9 in the left data character is an odd parity configuration consisting of a space of 3 modules, a bar of 1 module, a space of 1 module and a bar of 2 modules shown in a in the figure. Bar arrangement (total width of 2 bars is 3 modules) and bar arrangement of 2 modules shown in b in the figure, 1 module bar, 1 module space, 3 modules bar with even parity configuration (2 bars) The total bar width of 4 modules can be selected from two encodings, but on the right side Over data character is in the bar arrangement of the even parity on the total character both. The numeral 9 in the data character on the left side of the bar code in FIG. 3 is odd parity.

Also, an even number in the left data character,
Odd parity is used to embed an extra digit in a bar code which originally has only 12 digits, and it is possible to indirectly display another digit of this parity. For example, if the left-side data character “912345” in FIG. 3 is “odd-odd”, and the right-side data character “678904” is “difficult-difference”, it is indirectly indicated as the arrangement of the parities of the left-side data character. Since the relationship of the one-digit numbers shown in the table is defined as shown in the table below, the number "4" is assigned to the parity sequence, and this bar code as a whole is "4 91234.
5 678904 ".

[0007]

[Table 1] Thus, in the JAN code, the left and right data characters are separated by the center bar and the guard bar,
Further, since the left and right data characters have different parity configurations, one bar code can be decoded separately for the left and right sides and combined to restore one bar code.

The fact that the bar code can be divided and decoded is a great advantage especially for a stationary bar code scanner used in a large-scale mass retailer. That is, the stationary bar code scanner reads a bar code that enters in any posture in a universal direction by intersecting a plurality of laser scanning lines emitted in a plurality of directions with the bar code, but if the bar code cannot be divided and read. , Fig. 4
As shown in (a) of Fig. 4, if the scanning line l1 is not generated for each angle θ, the universal reading of the bar code cannot be realized, whereas in the case where divided reading is possible, it is shown in Fig. 4 (b). As described above, the scanning line l2 may be generated for each angle θ1 (> θ), and the universal reading can be performed with a smaller number of scanning lines as compared with the case where the divided reading cannot be performed. As a result, a great simplification of the device can be realized.

By the way, the width of the bar (space) of the bar code is considerably deformed by an error in printing the bar code, a factor of analog processing in the apparatus, and so on. However, the same barcode is read multiple times, and the read result is output only when the results match.

[0010]

With a bar code scanner, in addition to misreading that occurs when reading a printed bar code, random reading is also performed when a bar code other than the bar code is read, for example, a rag placed on the reading window surface. In some cases, a black and white combination is reproduced, which accidentally becomes the same signal as the bar code and causes misreading.

Considering the probability that a randomly decoded character string will be established as a JAN code, in the case of a right-side character, all the characters have an even parity structure, so that the right-side character string in the parity sequence is established. Although the probability is 1/2 ^6, since in the case of the left character sequence of parity indirectly represent the number of 0-9, the probability that the left character string is satisfied 10/2
^{As a result} , the left character is more likely to be coded and established as a result of being randomly decoded than the right character, which increases the probability of causing misreading.

Therefore, according to the present invention, a bar code having a character code on the left and right is dividedly read on the right and left sides, and the misreading rate of the left side character is reduced, thereby reducing the overall misreading rate and improving reliability. The present invention intends to provide a bar code reading device that can be used.

[0013]

According to the present invention, a bar code having a left and right character code is read a plurality of times for each of the left and right sides, and when the results of the plurality of times of reading are the same, the bar code read data is output to the outside. In the reading device, a right side character is read m times (however, m ≧ 2) times, and a judgment means for judging whether or not the reading results of the m times are coincident, and a left side character is n (however,
(n ≧ m) times of reading, a judging means for judging whether or not the reading results of the n times coincide with each other, and an output for synthesizing the read data on the left and right when the both judging means judge the coincidence of the reading results and outputting to the outside Means are provided.

[0014]

In the present invention having such a structure, the character on the right side is read m times and it is determined whether or not the read results of the m times match. For the character on the left side, it is read n times more than outside m and it is determined whether or not the reading results of the n times match. Then, in both judgments, when it is judged that the reading results match, the left and right read data are combined and output to the outside.

[0015]

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

As shown in FIG. 1, the laser beam from the laser oscillator 1 is converted into an optical system (not shown) such as a collimator lens.
After that, the polygon mirror 2 is irradiated with and deflected by the polygon mirror 2, the barcode label 3 is scanned by the deflected light, and the reflected light is received by the sensor 5 via the light receiving lens 4.
Then, the sensor output is taken into the photoelectric conversion unit 6 and converted into an electric signal, and the electric signal is binarized by the A / D conversion unit 7 and supplied to the decoder 8.

The decoder 8 decodes the fetched bar code data into left and right halves, and activates an interrupt signal IS to the microprocessor 9 when the half decoding is correctly performed.

The microprocessor 9 receives the data bus DB when the interrupt signal IS from the decoder 8 becomes active.
The decoded data is taken in from the decoder 8 via.

The microprocessor 9 internally has a counter LC for counting the number of times the left side character is currently matched.
T, a counter RCT that counts the number of matches of the current right character, and a check buffer L for the left character
BUF, right character check buffer RBUF
Also, a buffer BUF is provided, and the program control shown in FIG. 2 is performed.

That is, when the power is turned on, initialization is performed, the counters LCT and RTC are reset to 0, and the coincidence count set values LNUM = 2 and RNUM = 1 are set in the internal memory.

In this state, if there is an interrupt signal from the decoder 8, the decoding result of the left or right character is stored in the buffer B.
I am trying to incorporate it into the UF. Then, it is checked whether or not the parity arrangement of the buffer BUF is all even parity. If not all even parity, this data can be judged to be the left character, so it is subsequently checked whether or not the counter LCT is 0. If LCT = 0, it is the first data, so the data in the buffer BUF is stored in the buffer LBU.
Transfer to F, set the counter LCT to 1, and wait for the data from the decoder 8 to be fetched.

If LCT = 0 is not satisfied, the decoding result of the left character has already been set in the buffer LBUF, so that the data in the buffer LBUF is compared with the data in the current buffer BUF. When both data match, the counter LCT is incremented, and then it is checked whether the content of the counter LCT is larger than the matching count setting value LNUM = 2. When they do not coincide with each other, the counter LCT is reset to 0 and waits for the data to be fetched from the decoder 8.

Further, if the parity arrangement of the buffer BUF is all even parity, this data can be judged as the right character, so it is checked whether the counter RCT is 0 or not. Then, if RCT = 0, it is the first data, so the data in the buffer BUF is transferred to the buffer RBUF, the counter RCT is set to 1, and the acquisition of data from the decoder 8 is awaited.

If RCT = 0 is not satisfied, the decoding result of the right character is already set in the buffer RBUF, so the data in the buffer RBUF and the current buffer B are set.
Compare the UF data. When both data match, the counter RCT is incremented, and then it is checked whether or not the content of the counter RCT is larger than the matching count setting value RNUM = 1. When they do not coincide with each other, the counter RCT is reset to 0 and waits for the data to be fetched from the decoder 8.

The contents of the counter LCT and the matching count set value L
In the comparison with NUM = 2 and the content of the counter RCT and the match count setting value RNUM = 1, LCT> LN
If it is not UM or RCT> RNUM, it waits for the data from the decoder 8, and if LCT> LNUM and RCT> RNUM, the left character has been properly decoded three times, and the right character is 2 This means that the buffer RBUF has been successfully decrypted.
And the data in the buffer LBUF are combined and output as one bar code data to the host computer 10. After the output, the counters LCT and RTC are reset to 0 and wait for the fetching of data from the decoder 8.

In the embodiment apparatus having such a configuration,
The sensor 5 receives the reflected light of the laser beam obtained by scanning the bar code on the bar code label 3, and the electric signal obtained from the photoelectric conversion section 6 at that time is binarized by the A / D conversion section 7.
Captured by the decoder 8. The decoder 8 divides the fetched bar code data into left and right parts and decodes them, and when half the decoding is correctly performed, it activates the interrupt signal IS to the microprocessor 9. As a result, the microprocessor 9 stores the decoded half of the data in the buffer BUF.

The microprocessor 9 determines whether the fetched data is a left-side character or a right-side character based on the parity arrangement. That is, if all have even parity, it is determined to be the right character, and if not all have even parity, it is determined to be the left character.

In the case of the left character, the data in the buffer BUF is transferred to the buffer LBUF and the counter LCT is set to 1, and in the case of the right character, the data in the buffer BUF is transferred to the buffer RBUF and the counter RCT is set to 1.

The left character is buffered BUF for the second time
When it is stored in, the data in the buffer BUF and the data in the buffer LBUF are compared, and when they match each other, the counter LCT is incremented to 2. When the right character is stored in the buffer BUF for the second time, the data in the buffer BUF and the data in the buffer RBUF are compared, and if they match each other, the counter RCT is incremented to 2.

In the case of the left character, the counter L
Even if CT counts “2”, the matching count setting value LNUM
Since it does not become larger than = 2, the left character is captured for the third time. Further, in the case of the right character, when the counter RCT becomes “2”, the matching number setting value RNUM =
Since it is larger than 1, it is determined that the decryption is legal.

The left character is fetched for the third time, and this time, the data in the buffer BUF and the buffer RBUF are also fetched.
The counter LCT becomes "3" when the data of "1" are matched, and therefore LCT> LNUM, and it is determined that the left character is properly decoded.

When both the left and right characters are properly decoded in this way, the data in the buffers LBUF and RBUF are combined and output as one bar code data to the host computer 10.

For the left side character, the captured 3
If the two data do not match, the counter LCT is reset to 0 and the acquisition is performed again from the beginning. For the right character, if the two captured data do not match, the counter RCT is reset to 0 and the capture is performed again from the beginning.

In this way, the data comparison is performed once for the left character having a high probability of being established as a character string than for the right character, and as a result, the probability of being established as a character string can be lowered. Therefore, the misreading rate of the left character can be reduced. Further, since the probability that the right-side character is originally established as a character string is low, the misreading rate can be sufficiently lowered by determining that the character string is a normal character string if the data match twice consecutively.

In this way, the misreading rate of the left and right characters can be reduced, and the misreading rate of the bar code can be reduced as a whole, and the reliability can be improved.

In the above embodiment, the number of matching data of the left character and the right character is set to 3 times and 2 times, but the number of matching data is not necessarily limited to this and may be more. However, it is necessary to set the number of matching data of the left character to be larger than the number of matching data of the right character.

[0037]

As described above in detail, according to the present invention, in a bar code having a character code on the left and right sides is divided and read separately, the misreading rate of the left side character is reduced, and as a result, the entire character is reduced. It is possible to provide a bar code reader which can reduce the misreading rate and improve the reliability.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing main processing by the microprocessor of the embodiment.

FIG. 3 is a diagram for explaining the structure of a 13-digit JAN code.

FIG. 4 is a diagram showing angles between adjacent scanning lines when a barcode is read without dividing it and when it is divided and read.

[Explanation of symbols]

9 ... Microprocessor, LCT, RCT ... Counter,
BUF, LBUF, RBUF ... Buffer.

Claims (1)

[Claims] 1. A bar code reading apparatus for reading a bar code having character codes on the left and right a plurality of times for each of the left and right sides and outputting the bar code read data to the outside when the results of the plurality of times of reading are the same. Is m (however, m ≧ 2) times of reading, and a judgment means for judging whether the m times of reading results match, and n (however, n ≧ m) times of reading for the left character, and n times of reading. Determination means for determining whether or not the results match,
A bar code reading apparatus comprising an output means for synthesizing left and right read data and outputting the result to the outside when the two judging means judge that the reading results match.