JP2001256431A - Bar code reader, method for detecting start margin candidate by the same and method for reading bar code - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently read a bar code by simple hardware. SOLUTION: This reader has an m-stage data buffer part 5 reading a bar code and temporarily stores count data showing the width of each part of a binarized signal due to the density difference of the bar code as much as the number of optional stages, an n-fold device 7 multiplying the count data by (n), a comparator 9 comparing a piece of data selected by a selector part 8 among pieces of the count data stored in the m-stage data buffer part with the count data multiplied by (n) by the device 7 to detect start margin candidates, and a start margin candidate storing part 10 storing the data of the detected start margin candidates time sequentially.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code symbol reading device for reading a bar code symbol as bar code data by an optical reading means in a distribution system of articles or the like having the bar code symbol. The present invention relates to a start margin candidate detection method for detecting a start margin candidate for starting reading of a barcode symbol using a reading device, and a barcode symbol reading method using the detection result.

[0002]

2. Description of the Related Art When a bar code symbol is read by a bar code symbol reading device, it is necessary to detect a start margin candidate as preprocessing for decoding bar code symbol data. As a method of detecting the start margin candidate, it is known that a method widely used in the past corresponds to this by processing by software. Here, the “start margin candidate” is synonymous with the first candidate of the barcode symbol.

In a conventional bar code symbol reading device,
An example of a method of detecting a start margin candidate and reading a barcode symbol by generally known software will be described with reference to an example of time-series data indicating the width of each part of the barcode symbol shown in FIG. 5 and a flowchart of FIG. I do.

According to this method, in order to detect a start margin candidate by software from the time-series data shown in FIG. 5, as shown in FIG. , When it is black data, the data value (bar width) is n times (in this example, 3 times, d = storage data m × 3) and the data of the (m−1) th white data immediately before it This is realized by performing a comparison operation with the value and determining that the latter is a start margin candidate when the latter is larger than the former. Here, the value of “n” used for the above calculation is generally about 3 to 7. In addition, m is an arbitrary place in all the read data.

When a start margin candidate is detected using such conventional software, the software reads the start margin candidate until the start margin candidate is detected, that is, until the head candidate of the bar code symbol is detected. The above comparison operation is repeatedly performed for all of the data values obtained, and thereafter, the barcode symbol is read by shifting to the decoding process.

FIG. 5 shows an example of data of bar widths from the (m−2) th to (m + 3) th bar code symbols stored in time series. FIG. 6 is a flowchart showing an example of the start margin candidate detection processing by software when the above “n” is set to “3”. According to this example, when a white bar having a width of three times or more the black bar is immediately before, it is determined that the black bar is a start margin candidate. Also,
As another conventional example, there is a method of detecting the position of a barcode without using a microprocessor (CPU).

For example, as disclosed in Japanese Patent Application Laid-Open No. 3-144787, a scanner which reads a scanned image as two levels of data corresponding to white and black continuously inputs data of a level corresponding to "white". A measuring circuit for measuring a period, a comparing circuit for comparing the continuous input period calculated by the measuring circuit with a preset period, and a CPU for performing data processing based on a result of the comparison by the comparing circuit. On the other hand, there has also been proposed a method including a starting circuit for starting a barcode symbol recognition process, and detecting a start position of the barcode symbol by hardware to start the barcode symbol recognition process.

[0008]

However, in the above-described conventional bar code symbol reading method, when the start margin candidates are detected by software, the start margin candidates are not detected until the start margin candidates are detected. The decoding process cannot be started until the leading candidate of the symbol is detected. Therefore, it is necessary to repeatedly perform an operation on the read barcode symbol data until a start margin candidate is detected. Therefore, before decoding the barcode symbol data, a certain amount of time for detecting the start margin candidate is indispensable, and as a result, the reading time of the barcode symbol is affected.

The above-described method of detecting the start position of a barcode symbol by hardware and causing the CPU to start the recognition process of the barcode symbol also requires that the detected position of the black bar be a leading candidate of the barcode symbol. One that is (single)
Is transmitted to the CPU, and based on the signal, the CP
U will process, and as a result, will have to rely on software processing.

That is, in this case, the CPU directly takes in the output signal of the comparator (comparing circuit) for comparing the value of the start margin register with the value of the margin counter. If there is an error in the detection of the start margin candidate due to dirt or the like due to an external factor, the start margin candidate must be found again by software processing, which also takes a long detection time.

The present invention has been made to solve such a conventional problem, and it is possible to efficiently read bar code symbols with simple hardware without using software as in the above-described conventional example. And to detect a start margin candidate without error even when a printed barcode symbol is stained by printing stains or other external factors. . Thereby, it is another object to reduce the manufacturing cost of the bar code symbol reading device.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a bar code symbol is read, and count data indicating the width of each part of a signal binarized by a density difference is provided by an arbitrary number of stages. An m-stage data buffer for temporarily storing the data; an n-multiplier for multiplying the count data by n; a selected one of the count data stored in the m-stage data buffer; Comparing with the doubled count data, a comparator for detecting a start margin candidate, and a start margin candidate storage unit for storing data of the start margin candidate detected by the comparator in chronological order. A bar code symbol reading device is provided.

An m-stage data buffer unit for temporarily storing the bar code symbol count data for an arbitrary number of stages includes:
A storage circuit such as a flip-flop circuit or a memory can be used. An n-multiplier for multiplying the bar code symbol count data by n may be constituted by an arithmetic circuit.

Further, a start margin candidate detecting method according to the present invention uses the bar code symbol reading device described above.
A bar code symbol is read, and n times the set value of the count data of the black bar in the count data indicating the width of each part of the signal binarized by the density difference, and m steps of the set value of the bar before that. The count data is compared with the count data, and when the value of n times the count data is smaller than each of the count data values of the m stages, the count data of the black bar is detected as a start margin candidate, and the start margin candidate is detected. It is characterized in that it is stored in a storage unit in a time-series manner.

Further, in the bar code symbol reading method according to the present invention, the start margin candidates stored in the start margin candidate storage means in time series by the start margin detecting method are read by the microprocessor in time series order. The bar code symbols are sequentially called and barcode symbol recognition processing is attempted from the count data corresponding to the called start margin candidate.

If the barcode symbol data cannot be recognized, the barcode symbol recognition process is repeated from the count data corresponding to the next start margin candidate, and the barcode symbol data is recognized. It is characterized in that the barcode symbol recognition processing started from the count data corresponding to the first start margin candidate in time series is performed to the end to decode the barcode symbol.

[0017]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram of hardware for detecting a start margin candidate of a barcode symbol in a barcode symbol reading device according to the present invention, and is a diagram best representing the features of the present invention.

In FIG. 1, 1 is a bar code symbol to be read, 2 is an optical reading unit in a bar code symbol reading device, 3 is a bar code data value counting unit,
The barcode data output from the optical reading unit 2 is input, and a count operation is performed by the sampling clock from the sampling clock generation circuit 4 to convert the barcode data into count data (numerical values) indicating the width of white data and black data.

Reference numeral 5 denotes an m-stage data buffer unit for temporarily storing the count data output from the barcode data value counting unit 3 for m stages (m is an arbitrary integer), such as a flip-flop circuit or a memory. It is composed of a circuit. Reference numeral 6 denotes a count data value storage unit, which stores count data sequentially output from the barcode data value count unit 3.
It consists of a storage circuit such as a flip-flop circuit or a memory that stores and saves all in time series. Reference numeral 7 denotes an n-multiplier constituted by an arithmetic circuit for multiplying the count data by n.

Reference numeral 8 denotes a selector unit, which selects data to be compared among the m-stage count data temporarily stored in the m-stage data buffer unit 5. Reference numeral 9 denotes a comparator for comparing the data from the selector unit 8 with the data from the n-multiplier 7, and outputs a start margin candidate detection flag when the result of the comparison indicates that the data on the n-multiplier 7 side is smaller.
Reference numeral 10 denotes a start margin candidate storage unit having a storage function such as a flip-flop circuit, and stores a start margin candidate detection flag SMF output from the comparator 9 in association with the count data value to be compared at that time. .

Reference numeral 11 denotes an interface unit for inputting each data of the start margin candidate storage unit 10 and the count data value storage unit 6 to the microprocessor (CPU) 12. The CPU 12 is a microprocessor that executes a barcode recognition process based on the start margin candidate detection flag and the count data input through the interface unit 11. The CPU 12 is a ROM as a program memory and a RAM as a data memory. And the like.

In the above-described configuration, the bar code reading apparatus has the following features.
Light emitting diode (LED) and laser diode (LD)
Irradiate light from a light source such as a light source, and receive the reflected light with a light receiving element such as a photodiode or a phototransistor to convert it into an electric signal. It is converted to digital barcode data indicating a bar.

This is input to the bar code data value counting section 3 which counts by the sampling clock generated by the sampling clock generating circuit 4,
The count data is converted into count data that can be handled by the CPU 12. The count data is a numerical data string indicating the width of each white data and black data in the barcode symbol 1. The count data is stored in the count data value storage unit 6 and “m steps” according to the printing state of the barcode symbol.
Is also temporarily stored in the arbitrarily determined m-stage data buffer unit 5.

In detecting a start margin candidate, the count data that is about to be stored in the count data value storage unit 6 and the m that is temporarily stored first
It is necessary to compare the count data of the stage data buffer unit 5 with the count data. The selector unit 8 selects which data is to be compared among the m-stage data.

The selector section 8 determines in advance how many rows of data in the m-stage data buffer section 5 are to be compared by the CPU 12 or the like according to the printing state of barcode symbols, printing stains, and external factors. It can be set according to dirt or the like. This is defined as a set value m in the description of the present invention.

In comparing data, m
It is also necessary to set in advance whether the count data from the row data buffer unit 5 is larger than the count data value output from the barcode data value count unit 3 and is used as a start margin candidate. It is the n-multiplier 7 that performs the setting of “n” indicating the multiple and the calculation of n times. The setting of how many times the count data is to be multiplied in the n-multiplier 7 is also set in advance by the CPU 12 or the like according to the printing state of the barcode symbol and the like.
This is defined as a set value n in the description of the present invention.

The comparator 9 compares the data output from the n-multiplier 7 with the data of the m-stage data buffer 5 selected and output by the selector 8. At this time, if the data output from the n multiplier 7 is smaller, it is determined that there is a start margin candidate, and a start margin candidate detection flag SMF is output. The flag SMF is stored in the start margin candidate storage unit 10 in association with the latest count data stored in the count data value storage unit 6 so as to determine which count data has become a start margin candidate.

Although the number of start margin candidates is not limited to one, each time the start margin candidate detection flag SMF is generated, the flag SMF and the count data compared at that time are stored in the start margin candidate storage unit 10. Are sequentially stored. However, the start margin candidate is generated when a white bar having a certain width or more exists before the black bar in the barcode symbol 1.

The start margin candidate storage unit 1
Start margin candidate detection flag S stored in 0
The MF and the count data stored in the count data value storage 6 are transmitted to the C
It can be read by PU12. These components are all constructed by hardware.

Several embodiments of a method for detecting a start margin candidate using the bar code symbol reader shown in FIG. 1 will be described with reference to FIGS. FIG.
FIG. 4 is a diagram for explaining a flow of barcode data in hardware for detecting a start margin candidate according to the present invention described with reference to FIG. 1 and an operation until a start margin candidate is detected, according to the first embodiment; Here is an example.

In FIG. 2, the bar code symbol shown in FIG. 2A is read by the optical reading unit 2 and converted into binary bar code data as shown in FIG. In this example, the white level is "0" and the black level is "1". This barcode data is stored in a barcode data value
Thus, the duration (width) of each level is counted at the cycle of the sampling clock, and is converted into count data shown in FIG.

That is, the count data indicates the width of the shade (black bar and white bar) of the symbol in the bar code symbol 1, and the wider the symbol, the larger the value of the count data. That is, the value of the count data is proportional to the width of the black bar or the white bar constituting the barcode symbol 1. The count data represents each width of the barcode symbol by the number of pulses of the sampling clock from the sampling clock generating circuit 4 shown in FIG.

Further, FIG. 2C shows the data of the parts (a) to (h) of the count data, but the data of the part (a) is the oldest in time series.
(H) The data of the part is the newest. That is, the count data is stored in time series in the m-stage data buffer unit 5 shown in FIG.

In the first embodiment, it is artificial to previously set the set value m to "2" (m = 2) in the selector unit 8 of FIG. 1 and always compare the set value m with the data up to two before. Is set to The set value n is previously stored in the n-multiplier 7 of FIG.
Is set to “3”, and the count data is always tripled.
This is also set artificially. The part (a) of the count data (C) shown in FIG. 2 will be described. Here, a value “100” corresponding to the width of a white bar symbol is stored.

Next, when the value "20" corresponding to the width of the black bar symbol immediately after the white bar symbol is stored in the portion (b), the set value is set in the first embodiment. n
= 3 is set in advance, and when this black bar symbol is output as count data through the n-multiplier 7, the output value is “20 × 3 = 60”. This value is calculated by the comparator 9 shown in FIG.
The data value is compared with the data value “100” already stored in the m-stage data buffer unit 5 at the time of the copy (comparison 1).

As a result of the comparison, 60 <100, the start margin candidate is detected, and the start margin candidate detection flag of (D) becomes "1" in a portion corresponding to the (b) portion of the count data. The start margin candidate detection flag is "1" to indicate detection, and "0" indicates no detection.

Next, focusing on the part (d) of the count data shown in (C), the count data at this time is "2".
0 ". Here, since the set value m = 2, the data (b) and the data (c) up to the immediately preceding data in the time series are to be compared. Further, the set value n = 3 of the n-multiplier 7 is set, and when this black bar symbol is output as count data, the output value of the n-multiplier 7 is “20 × 3 = 6”.
0 ". This value is compared with the (b) and (c) parts of the count data in the comparator 9 (Comparison 2), which is larger than the (20) of the (b) part and the 35 of the (c) part. The margin candidate detection flag is not generated, and is set to “0”.

Thereafter, this process is repeated, and the start margin candidates are automatically detected by the hardware sequentially, and the start margin candidate detection flag is stored in the start margin candidate storage unit 10 of FIG.

Focusing on the (h) part of the count data shown in FIG. 2C, the count data at this time is "20", and the output value of the n-multiplier 7 is "(h) × 3". = 2
0 × 3 = 60 ”. This value is obtained by the comparator 9
It is compared with the (g) and (f) parts of the count data (comparison 4). As a result, since the count data of the portion (g) is “35”, (g) <(h) × 3, so that
The count data of the immediately preceding (f) part is compared in time series. The count data of the section (f) is “7
Since “0”, (f)> (h) × 3, the start margin candidate is detected, and the start margin candidate detection flag becomes “1” in a portion corresponding to the (h) portion, and the start margin candidate storage unit 10 Is stored in

Thus, the detected start margin candidate detection flag is stored in the start margin candidate storage unit 1 shown in FIG.
0, the time series (a) to (h)... Of the count data of (C) as shown in (D) of FIG. 2 (the count data sequence stored in the count data value storage 6) It is stored in a form that can be compared with.

The CPU 12 in FIG. 1 stores a predetermined bar code recognition code, for example, a JAN code, in a memory, and sequentially calls data stored therein from the start margin candidate storage unit 10. A bar code symbol recognition process (decoding operation) based on the JAN code is attempted based on the count data sequence from the called start margin candidate. If the bar code symbol data cannot be recognized, the count from the next start margin candidate is counted. The bar code symbol recognition process is repeated by repeating the data sequence, and the bar code symbol recognition process started from the count data of the first start margin candidate in chronological order that can be recognized as bar code symbol data is terminated. Go to and read the barcode symbol.

FIG. 3 shows a second embodiment of a start margin candidate detecting method using the bar code symbol reading apparatus shown in FIG. The second embodiment is a case in which a start margin candidate is detected when there is a print stain or a stain due to an external factor such as a hand before the barcode symbol. Here is an example of the case where it exists before.

The bar code symbol shown in FIG. 3A is read by the optical reading section 2 in FIG. 1, converted into binary bar code data shown in FIG. 1B, and further converted to a bar code data value count. The conversion into count data as shown in (C) by the unit 3 and the storage of the count data in the m-stage data buffer unit 5 and the count data value storage unit 6 in time series are the same as in the first embodiment. is there. Therefore,
Detailed description of the process is omitted.

Also in the second embodiment, the set value m previously set in the selector section 8 in FIG. 1 is 2 (m = 2).
Thus, the set value n set in the n-multiplier 7 is also 3 (n = 3), which is the same as in the first embodiment. The second embodiment shown in FIG. 3 is an example in which a start margin candidate is detected when there are several stains before the barcode symbol as described above. explain.

In the count data shown in (C) of FIG. 3, (a) shows "6" corresponding to the width of the white bar symbol.
"0" is stored. Next, in part (b),
The value “15” corresponding to the width of the black bar symbol immediately after the white bar symbol is stored. Also in the second embodiment, since the set value n = 3 is set as in the first embodiment, when the stain corresponding to the black bar symbol is output as count data, it is increased by n times. The output value of the unit 7 is “15 × 3 = 45”.

This value is “60”, which is the data value already stored in the m-stage data buffer unit 5 at the time point (a) of the count data by the comparator 9 shown in FIG.
Is compared with (comparison 1). As a result, (a)
> (B) × 3, it means that a start margin candidate has been detected, and the start margin candidate detection flag shown in (D) of FIG. 3 is set to 1 at a portion corresponding to the (b) portion of the count data. Become. This detection flag is stored in the start margin candidate storage unit 10.

Next, focusing on the part (d) of the count data shown in FIG. 3 (C), the value of the count data at this time is “8”, and the output value of the n-multiplier 7 is “ 8 × 3 =
24 ". Here, since the set value m is 2, the data up to two values before this value in time series are to be compared (
The comparison 2) shows that the value “24” is the data value “15” already stored at the time of the parts (b) and (c).
And greater than "8". Therefore, the start margin candidate detection flag is not generated and is “0”.

Thereafter, the above operation is repeated, and the start margin candidates are automatically detected sequentially by the hardware shown in FIG. 1 and the detection flag is stored in the start margin candidate storage unit 10.

Next, focusing on the part (h) in the count data shown in FIG. 3C, the count data at this time is “20”, and the output value of the n-multiplier 7 is “20”.
× 3 = 60 ”, and the data of the part (g) immediately before is“ 6 ”.
5 ", and when compared with it (comparison 4),
Since (g)> (h) × 3, the start margin candidate is detected again in this case, and the start margin candidate detection flag shown in FIG.
It becomes "1" in the part corresponding to the part.

As described above, also in the second embodiment, under the condition that the start margin candidate has been detected once, the operation of detecting the start margin candidate is not stopped, and the above-described comparison operation is continued by hardware. All the start margin candidates are sequentially detected and stored.
The start margin candidate detection flag detected in this manner is stored in the start margin candidate storage unit 10 of FIG. 1 from the (a) part of the count data shown in (C) to (h) as shown in (D) of FIG. ) Part (a count data string stored in the count data value storage part 6)
It is stored in a form that can be compared to 1: 1.

By the way, when observing FIG. 3 of the second embodiment, a start margin candidate is detected in a portion corresponding to the portion (b) in the count data of (C). Thus, the portion (b) that appears to correspond to a black bar on the barcode data is not the bar itself to be decoded but a black stained portion.

Therefore, if the CPU 12 considers this portion as a start margin of the bar code symbol and starts decoding the count data string read from the count data value storage section 6, the code does not become a normal code. This is not recognized as a predetermined bar code symbol. In such a case, the CPU 12 immediately stops the decoding process and searches for a next start margin candidate detection flag in order to decode a normal barcode symbol.

Then, the CPU 12 moves to the next operation, and detects the part (h) of the start margin candidate detection flag shown in (D) of FIG. Then, the CPU 12 regards the (h) portion as the start of the barcode symbol for the count data sequence read from the count data value storage 6 and starts the decoding process. In this decoding process, unlike in the previous case, the CPU 12 recognizes the count data sequence after the (h) copy shift corresponding to the start margin candidate detection flag as barcode data, and completes the decoding process to the end. Continue and read the barcode.

As described above, the CPU 12 shown in FIG.
The stored data is called from the start margin candidate storage unit 10 and, at the same time as in the first embodiment, the time at which the start margin candidate was found is recognized, and the first time-series data recognized as barcode symbol data is recognized. A start margin candidate detection flag is detected, and a barcode is read by performing recognition (decoding) processing on the count data sequence read from the count data value storage unit 6.

The reason why the CPU 12 does not recognize the bar code data as the bar code symbol data even though the CPU 12 handles the portion (b) in FIG. 3C as a start margin candidate is the first embodiment described above. As described above, the CPU 12, for example, JAN
The code is stored in the memory, and the CPU 12 initially treats the data of the part (b) as a start margin candidate. However, for the count data sequence (data configuration) after the start margin candidate of the part (b), It recognizes (decodes) whether or not the data is barcode symbol data.

That is, the CPU 12 determines and processes whether or not such a start margin candidate is normal or due to dirt or the like in a decoding process.

Next, a third embodiment will be described with reference to FIG. Similar to the second embodiment, the third embodiment is an example relating to detection of a start margin candidate of a barcode symbol in the case where there is a print stain or oil stain before the barcode symbol. Is present immediately before a bar code symbol.

In such a case, if the number m of comparison stages is set to 2 as described in the second embodiment, there is a problem in detecting a start margin candidate of a bar code symbol. That is, in the third embodiment shown in FIG. 4, similarly to the second embodiment, the number m of comparison stages is set to m = 2, and n times the amount of n is set to n.
= 3, the data value of the (f) part of the count data shown in (C) is “12”, so that the output value of the n-fold amount is “12 × 3 = 36”, which is equivalent to m stages, that is, 2
"2" in the part (e) and the part (d) of the count data before the stage.
The start margin candidate detection flag is not detected in this part (f) because it is compared with "0" and "15", respectively. In this case as well, in the third embodiment, the start margin candidate at the head of the bar code symbol can be detected.

Therefore, in the third embodiment, the number m of comparison stages is m = 4, and the number n of n times is n = 3. In the count data shown in FIG. 4C, a value of “60” corresponding to the width of the white bar symbol is stored in the part (a). Next, in the part (b), the symbol (dirt) corresponding to the black bar immediately after the white bar is counted data “1”.
5 ”, and the output value of the n-multiplier 7 is“ 15 × 3 =
45 ". This value is compared with the comparator 9 as in the second embodiment shown in FIG. 3, and since 45 <60,
(A)> (b) × 3. Therefore, the start margin candidate is detected, and the start margin candidate detection flag shown in (D) becomes “1” in a portion corresponding to the portion (b).

Next, focusing on the portion (d) corresponding to the width of the black stain (black bar) immediately before the bar code symbol, the count data value at this time is "15",
Since the set value n = 3, the output value of “15 × 3 = 4
5 ". Here, since the set value m = 4, the data up to four data in time series is to be compared with the output value of the n-multiplier 7. First, the count data is compared with the stored value “65” of the part (c) immediately before the part (d), so that 45 <65.
The start margin candidate detection flag shown in (D) becomes “1” in a portion corresponding to the portion (d) of the count data.

Next, focusing on the part (f) in the count data, the count data at this time is “12”, and the output value of the n-multiplier 7 is “12 × 3 = 36”. Here, in this embodiment, since the number m of comparison stages is set to m = 4 (count data up to four counts in time series are to be compared), first, the number of comparison stages is compared with the count data “20” in the part (e). Then, since 20 <36, (e) <(f) × 3, and no start margin candidate is detected.

Next, when compared with the count data "15" of the preceding (d) part, since 15 <36, (d) <
(F) × 3, and no start margin candidate is detected. Further, when compared with the count data “65” of the preceding part (c), 65> 36, so that (c)>
(F) × 3, where the start margin candidate is detected for the first time, and the start margin candidate detection flag shown in (D) is set in the part corresponding to the (f) part of the count data shown in (C). It becomes “1”.

Also in the third embodiment, FIG.
Although start margin candidates are detected in the parts (b) and (d) in the count data shown in FIG.
As apparent from FIG. 4A, the bar code data appears to correspond to a black bar (b) and (d).
The part is not a bar itself to be decoded, but a black stained part.

Therefore, in this embodiment, as in the case of the above-described second embodiment, the CPU 12 in FIG. 1 is stored in the start margin candidate storage section 10 in order to decode a normal bar code symbol. The start margin candidate flags are sequentially read out in chronological order,
A decoding process is attempted on the count data sequence from the count data, and a time-series first start margin candidate detection flag recognized as barcode symbol data. In the example shown in FIG. A margin candidate detection flag is detected. Then, the barcode symbol recognition (decoding) operation started from the count data corresponding to the flag is continued to the end to read (decode) the barcode symbol.

By the way, in the three embodiments described above, an example in which the set value of the number m of comparison stages is set to 2 and 4 has been described. Thus, it is possible to set it arbitrarily arbitrarily, and the timing and method for arbitrarily setting include the following methods.

1. A method in which a human observes a printing state and a stain state before starting reading a barcode symbol and sets the state via the CPU 12. 2. When the bar code symbol cannot be read, the bar code is reset via the CPU 12 by manual operation. 3. If the bar code symbol cannot be read, the CPU 12
Is determined by the CPU 12 itself before the optical reading unit 1 performs the next reading operation.

In practicing the present invention, the number m of comparison stages may be set using any of these methods. Also, n
The setting value n of the multiplier 7 has been described in each of the above embodiments only when the setting multiple is 3, but may be set to about 3 to 7 depending on the characteristics of the bar code symbol.

The ratio of the data width (count data value) of each part constituting the barcode symbol in each of the above-described embodiments is not for the actual barcode, but is for the purpose of describing the embodiment. .

[0069]

As described above, according to the present invention. By providing the m-stage data buffer unit in the bar code symbol reading device, the data up to an arbitrary m-stage before can be compared with the current count data, so that the range of start margin candidate detection can be greatly expanded. Can be. Further, by providing the n-multiplier, it is possible to compare the current count data to an arbitrary n-fold value, and to set the magnification to an optimum value according to the type of the bar code, etc. Detection accuracy can be improved.

Further, the start margin candidate is automatically detected by hardware when the count data is stored, and the detection flag is stored in the start margin candidate storage unit, thereby eliminating the start margin candidate detection processing (calculation) by the CPU. In addition, since a plurality of start margin candidates can be stored, even when one of the start margin candidates is erroneous, the decoding process of the barcode data by the CPU can be quickly restarted from the next start margin candidate. Therefore, the software can be simplified and the barcode symbol reading time can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of hardware for detecting a start margin candidate of a barcode symbol in a barcode symbol reader according to the present invention.

FIG. 2 is an explanatory diagram for explaining a first embodiment for detecting a start margin candidate of a bar code symbol using the hardware of FIG. 1;

FIG. 3 is an explanatory diagram for explaining a second embodiment.

FIG. 4 is an explanatory diagram for explaining a third embodiment.

FIG. 5 is a diagram showing a bar code symbol bar width count data string stored in time series for explaining a conventional bar code symbol start margin candidate detection method.

FIG. 6 is a flowchart of a process for detecting a start margin candidate using conventional software.

[Explanation of symbols]

 1: bar code symbol 2: optical reading unit 3: bar code data value counting unit 4: sampling clock generation circuit 5: m-stage data buffer unit 6: count data value storage unit 7: n-folder 8: selector unit 9: comparison Unit 10: Start margin candidate storage unit 11: Interface unit 12: Microprocessor (CPU)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jin Yoshishima 833-6, Kami Kamisato-cho, Kodama-gun, Saitama Prefecture Inside Tesco Saitama Plant, Ltd. (72) Inventor Hidefumi Morita 833-6, Kami Kamisato-cho, Kodama-gun, Saitama F-term (reference) in Tesco Saitama Plant of the stock company 5B072 AA01 CC24 DD01 FF00

Claims (5)

[Claims] An m-stage data buffer unit for temporarily storing, for an arbitrary number of stages, count data indicating the width of each unit of a signal obtained by reading a bar code symbol and binarizing the signal according to a density difference; N is multiplied by n, and the selected data of the count data stored in the m-stage data buffer unit is compared with the count data multiplied by n by the n-multiplier to determine a start margin candidate. A bar code symbol reading device comprising: a comparator for detecting; and a start margin candidate storage unit for storing data of the start margin candidate detected by the comparator in a time-series manner. 2. The m-stage data buffer unit is configured by a storage circuit such as a flip-flop circuit or a memory.
The bar code symbol reader of the description. 3. The bar code symbol reading device according to claim 1, wherein said n-folder is constituted by an arithmetic circuit. 4. Count data indicating the width of each part of a signal obtained by reading a barcode symbol using the barcode symbol reader according to claim 1 and binarizing the signal based on a density difference. Is compared with each count data of the set value of the count data of the black bar at m stages and the set value of the previous bar of m stages, and the value of n times of the count data is set at each count of the m stages. A bar code symbol start margin candidate detection method, wherein when the data value is smaller than any of the data values, the count data of the black bar is detected as a start margin candidate and stored in a start margin candidate storage unit in time series. . 5. The microprocessor sequentially calls the start margin candidates stored in the start margin candidate storage means in chronological order by the start margin detecting means according to claim 4. Then, the barcode symbol recognition process is attempted from the count data corresponding to the called start margin candidate, and if the barcode symbol data cannot be recognized as barcode symbol data, the barcode symbol is calculated from the count data corresponding to the next start margin candidate. The barcode symbol recognition process started from the count data corresponding to the first start margin candidate in chronological order, which was recognized as barcode symbol data, was repeated until the barcode symbol data was recognized as barcode symbol data. Bar code symbol reading characterized by decoding code symbols How to take.