JP2003036416A - Barcode reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barcode reader and a reading method capable of completing barcode reading in a short time without having to frequently correcting a scanning direction. SOLUTION: A barcode recognition/demodulator circuit 10 mutually compares data strings including a start bar but including no end bar with data strings including the end bar but including no start bar among various data strings obtained, by a scanning/convergence optical system 2, by scanning a barcode 3a. The circuit 10 detects the total sum of the numbers of digits of both of the data strings and checks whether or not the total sum is more than the number of digits of a barcode type to be a read object. In the case the total sum is more, the circuit 10 checks whether data of an overlapping parts of the both data strings coincide with each other or not. If the data coincide with each other, read data corresponding to the entire barcode are combined based on the both data strings.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reading apparatus and a method for reading a bar code sandwiched by a start bar and an end bar, and more particularly to a start bar including read data including the start bar but not the end bar and the end bar. The present invention relates to a bar code reading device that obtains read data based on the entire bar code by synthesizing the read data that does not include the.

[0002]

2. Description of the Related Art In recent years, as represented by POS systems in the distribution industry and the like, it has become common to manage products and the like by bar codes. For example, in a POS system of a store, information such as a product type and a selling price is coded in a barcode format and attached to the product. Then, by reading this bar code at the cash register, the payment is made and the number of products sold is calculated in real time, which is useful for inventory management and purchase management.

By the way, such a bar code is WP
It is roughly classified into fixed length codes such as C code, UPC code and EAN code, and variable length second code. The variable length code is a code whose length (the number of bars) is not defined in the standard, and is, for example, ITF (Interleaved Two of Fiv).
e) Code, CODE39, NW7, CODE128,
Etc.

The above-mentioned fixed length code has a guard bar added to both front and rear ends and a center bar inserted in the middle part, and 4 or 6 data characters are stored between each guard bar and the center bar. Has been done.
In this case, even if only the first half data character is read, since this data character is sandwiched between the guard bar and the center bar on the tip side, it can be recognized as the data forming the barcode. Similarly, even if only the latter half of the data character is read, it can be recognized as the data forming the barcode because the data character is sandwiched between the center bar and the guard bar on the rear end side. Therefore, the read data of the entire barcode can be combined based on the data obtained by separately reading the first half data character and the second half data character that form the barcode.

On the other hand, as shown in FIG. 9, the second code has a start bar (start character) SB on the front end side and an end bar (end character) E on the rear end side.
Data character DC having variable length B and having a length between both bars
Is stored. Then, as in the case of the fixed length code, the conventional barcode reading apparatus recognizes only the data having both ends surrounded by the bar as the data character DC forming the barcode.

Therefore, the conventional bar code reading apparatus, as shown by "C" in FIG. 10, shows only the data character in which the entire bar code sandwiched by the start bar SB and the end bar EB is read all at once.
It could not be recognized as the data that constitutes the barcode. That is, in FIG. 10, the read data including the start bar indicated by "A" but not including the end bar and the read data including the end bar indicated by "B" but not including the start bar are the data forming the barcode. Since it is not recognized as the character DC, the read data of the entire bar code cannot be synthesized based on these data.

FIG. 15 shows a data reading process by the conventional bar code reading device. In the first step S501 after the start of the data reading process, the initial setting is executed. That is, the data character length (reading digit number) of the second code to be read is set.

In the next S502, the detection of the start bar is awaited. That is, it is checked whether the read data includes the start bar. In S503 executed when the start bar is detected, the end bar detection is checked. That is, it is checked whether the read data includes the end bar. If the end bar is not detected, the read data does not include both bars, so that the process is returned to S502 because it is not guaranteed that the data is the data forming the barcode.

S5 executed when both bars are detected
In 04, the length of the first character (character adjacent to the start bar) is checked. Then, if the length of the first character is out of the standard, the process returns to S502.
On the other hand, if the length of the first character is in conformity with the standard, the first character is converted into corresponding data in S505.

In step S506, the length of the adjacent character is checked. Then, if the length of this character is out of the standard, the process is returned to S502. On the other hand, if the length of this character is in conformity with the standard, this character is converted into corresponding data in S507.

At the next step S508, steps S505 and S507 are performed.
Check if the data demodulation by is good. Then, if the data demodulation is not successful, the process proceeds to S50.
Return to 2.

On the other hand, if the data demodulation is good,
In S509, it is checked whether the adjacent character (the character adjacent to the character that is the processing target in S507) is the end character (end bar) or the start character (start bar). Then, if it is other than the end character and the start character, the process is returned to S506 to demodulate the adjacent character.

On the other hand, if it is the end character or the start character, it is determined that the demodulation of all the data characters is completed, and the demodulated data is stored in S510. Then, in the next S511,
The demodulated data is transmitted to the data processing device, and the process returns to S502 for demodulation of the next bar code.

[0014]

However, generally, the second bar is a truncated label having a narrow width W (see FIG. 9). Therefore, for example, among various data obtained by scanning a barcode in various directions by a fixed scanning device, read data including a start bar SB and an end bar EB as indicated by "C" in FIG. Hereinafter, "continuous reading data") is extremely small. Therefore, in the conventional reader, it took a long time to complete the reading of the bar code, and the scanning direction had to be corrected many times before the reading was completed.

In view of the above problems, an object of the present invention is to adopt a means for suppressing misreading of data as much as possible, so that read data including a start bar indicated by "A" in FIG. 10 but not including an end bar, Also, it enables the synthesis of read data by the entire barcode based on the read data including the end bar but not including the start bar indicated by "B", and the barcode can be read in a short time without frequent correction in the scanning direction. The object is to provide a bar code reader capable of completing reading.

[0016]

In order to solve the above-mentioned problems, the bar code reader according to the present invention has a first bar (100a) and a second bar (100b) as shown in the principle diagram of FIG. A bar code (10
0), and a light and dark pattern detecting means (101) for detecting a light and dark pattern data string in the scanning locus,
Data conversion means for dividing the light / dark pattern data sequence detected by the light / dark pattern detection means into data of the other format corresponding to each character, and the first bar (100a) are included. 2 bars (10
0b) is not included in the first light-dark pattern data string converted by the data converting unit and the second bar (10).
0b) but not the first bar (100a) and the second light-dark pattern data string converted by the data converting means is the light-dark pattern detecting means (101).
And an overlapping portion determination unit (102) that determines whether or not an overlapping portion formed of the same data is included in each of the first light-dark pattern data sequence and the second light-dark pattern data sequence when detected by , The first bright-dark pattern data string and the second bright-dark pattern data string each include the overlapping portion, when the overlapping portion determining means (102) determines that the first bright-dark pattern data A combination means (103) for connecting the column and the second light / dark pattern data row, a threshold setting means for presetting a threshold value of the number of characters of the overlapping portion, the first light / dark pattern data row and the The comparison means for comparing whether or not the number of characters of the overlapping portion included in the second light-dark pattern data string is smaller than the threshold value, and the comparison result by the comparison means. When the number of characters in the overlapping portion is less than the threshold value, the determination made by the overlapping portion determining means is newly detected by the bright / dark pattern detecting means, and the first bright / dark pattern data string and the second And a judgment re-execution means for executing the light-dark pattern data sequence.

According to the bar code reading apparatus of the present invention, the light and dark pattern detecting means (101) includes the first bar (100).
The bar code (100) whose both ends are sandwiched by a) and the second bar (100b) is scanned to detect a bright / dark pattern data string in the scanning locus. The light / dark pattern data string detected by the light / dark pattern detecting means (101) and converted by the data converting means includes the first bar (100a) but does not include the second bar (100b). Light and dark pattern data sequence of
And a second bar (100b) but a first bar (1
(00a) does not include the second light-dark pattern data sequence in the scanning locus, the overlapping portion determination means (102)
Determines whether or not the first light-dark pattern data string and the second light-dark pattern data string each include an overlapping portion formed of the same data. A threshold value for the number of characters included in the overlapping portion is set in advance by the threshold value setting means, and is included in each of the first light-dark pattern data string and the second light-dark pattern data string. If the number of characters in the overlapping portion is smaller than the threshold value, the comparing means compares the results, and as a result of the comparison by the comparing means, if the number of characters in the overlapping portion is less than the threshold value,
The determination re-execution unit executes the determination by the overlapping portion determination unit on the first bright-dark pattern data sequence and the second bright-dark pattern data sequence newly detected by the bright-dark pattern detection unit. In this way, the overlapping part determination means (102) determines that the first bright-dark pattern data string and the second bright-dark pattern data string each include the overlapping part, and the overlapping part is included in the overlapping part. When the number of existing characters is larger than the threshold value, the first light / dark pattern data string and the second light / dark pattern data string are combined. As a result, the combination is performed only when the first light-dark pattern data string and the second light-dark pattern data string sufficiently overlap each other. Therefore, erroneous reading of data can be suppressed as much as possible, and it is possible to synthesize read data of the entire bar code based on these bright and dark pattern data strings. Therefore, it becomes possible to complete the reading of the bar code in a short time without requiring frequent correction in the scanning direction. Further, when the number of duplicate characters is less than the threshold value, it is possible to read and determine the light and dark pattern data string again, so even if there is a possibility of misreading data,
The mixture can be prevented.

The constituent features of the present invention will be described below. (Brightness / darkness pattern detecting means) The bright / darkness pattern detecting means may optically read the bright / dark pattern, but in that case, the irradiation light emitted from the light emitting portion may be scanned or the light receiving portion may be scanned. Is also good. (Barcode) The barcode may be a fixed length or a variable length, as long as it is a barcode sandwiched between a first bar and a second bar having a predetermined fixed pattern. When using a variable-length bar code, CO
It can be DE128, CODE39, ITF, NW7, etc.

In any of these, the bar code is
It is composed of a plurality of characters respectively corresponding to other types of data (code data). In this case, the bar code reading device may further include a data conversion unit that divides the light-dark pattern data string detected by the light-dark pattern detection unit into each character and converts the divided data into data of another corresponding format. In that case, the overlapping portion determination means
The determination is performed on the first light-dark pattern data string and the second light-dark pattern data string that have been converted into data of another format by the data converting means. By doing this, the processing can be performed after removing the noise that cannot form the character, so that the erroneous reading of the data can be further prevented.

Further, a character number specifying means for specifying the number of characters of the bar code to be read by the bar code reader may be further provided. (Overlapping part determining means) The overlapping part determining means is specified by a total sum calculating means for calculating the sum of the number of characters in the first light-dark pattern data string and the number of characters in the second light-dark pattern data string, and the character number specifying means. The above-mentioned determination is performed only when the total number calculated by the total sum calculation unit is compared with the total number calculated by the total sum calculation unit, and the total sum exceeds the specified number of characters as a result of comparison by the comparison unit. You may do it. This is because it is meaningless to make the above determination because there can be no overlapping portion unless the total sum exceeds the number of characters of the specified barcode.

Further, the overlapping portion determining means is specified by a total sum calculating means for calculating the total sum of the number of characters in the first light / dark pattern data string and the number of characters in the second light / dark pattern data string, and the character number specifying means. And a comparing means for comparing the combined digit number set by the combined digit number setting means with the total sum calculated by the total sum calculating means. At the same time, the determination may be performed only when the total sum exceeds the combined digit number as a result of comparison by the comparison means. By changing the number of composite digits, the lower limit of the number of characters in the overlapping portion can be changed. As a result, by mixing the lower limit of the number of characters in the overlapping portion in accordance with the set number of characters of the barcode, it is possible to further prevent the mixing of data due to erroneous reading.

It is desirable that the composite digit number setting means sets the composite digit number larger as the character number specified by the character number specifying means increases. This is because if the number of specified characters becomes large, the probability that the same pattern will accidentally be mixed due to misreading in both light and dark pattern data strings can be increased, so that misread data can be prevented from being mixed by increasing the threshold value. .

The following constitutional requirements may be added to the constitution of the present invention. <Effective character number setting means, discarding means> Effective character number setting means for setting the effective character number of the light and dark pattern data string corresponding to the character number specified by the character number specifying means, and the effective character number setting means. Further, a discarding means for discarding the light and dark pattern data string having the number of characters less than the number of effective characters may be further provided. In this way, extremely short bright and dark pattern data strings can be removed. Such a short light-dark pattern data string may be indistinguishable from the misread data in appearance. Therefore, by removing such a short light-dark pattern data string, the mixture of misread data can be suppressed as much as possible.

It is preferable that the effective character number setting means sets the effective character number to be larger as the number of characters specified by the character number specifying means increases. This is because, if the number of specified characters becomes large, there is a high possibility that the data due to erroneous reading will have the same form as the bright and dark pattern data sequence at first glance. <Threshold deciding means, comparing means, determination re-executing means> Threshold setting means for setting a threshold value of the number of characters in the overlapping portion corresponding to the number of characters specified by the number-of-characters specifying means; Comparison means for comparing whether or not the number of characters in the overlapping portion included in each of the light and dark pattern data string and the second light and dark pattern data string is less than a threshold value, and as a result of the comparison by the comparing means, When the number of characters is less than the threshold value, the above-mentioned determination by the overlapping part determination means is newly detected by the light / dark pattern detection means, and the first light / dark pattern data sequence and the second
And a determination re-execution unit for executing the light-dark pattern data sequence. With this configuration, when the number of duplicated characters is less than the threshold value, the light and dark pattern data string can be read again for determination, so that even if there is a possibility of misreading data, Mixing can be prevented. Further, since this threshold value is varied according to the number of characters set by the character number setting means, it is possible to minimize the possibility of misreading data being mixed depending on the number of characters of the barcode.

It is preferable that the threshold value setting means sets the threshold character number to a larger value as the character number set by the character number setting means increases. If the number of set characters becomes large, it is more likely that the characters included in each light / dark pattern data string will accidentally take the same form due to erroneous reading.Therefore, it is possible to prevent erroneous reading data from being mixed by increasing the threshold value. is there.

The barcode reading method according to the present invention is a first method.
Scanning the bar code whose both ends are sandwiched by the first bar and the second bar to detect the bright and dark pattern data sequence in the scanning locus, and the scanning including the first bar but not the second bar When the first light-dark pattern data string in the locus and the second light-dark pattern data string in the scanning locus including the second bar but not the second bar are detected by the light-dark pattern detecting means,
It is determined whether or not the first light-dark pattern data sequence and the second light-dark pattern data sequence each include an overlapping portion formed of the same data, and the first light-dark pattern data sequence and the second light-dark pattern are determined. When it is determined that the data string includes the overlapping portion, the first light-dark pattern data string and the second light-dark pattern data string are combined.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 2 is a block diagram showing the schematic arrangement of a bar code reading apparatus according to the first embodiment of the present invention. (Overall Structure) In FIG. 2, a laser light source 1 is a semiconductor laser that emits a laser beam L. The laser beam L emitted from the laser light source 1 is incident on the scanning / focusing optical system 2. The scanning / focusing optical system 2 is an optical system that deflects the laser beam L by a polygon mirror and reflects the deflected laser beam in various directions by a plurality of fixed mirrors. According to the scanning / focusing optical system 2, laser beam scanning in a plurality of directions is continuously performed at high speed in the upward direction of the scanning / focusing optical system 2 within a deflection cycle by one reflecting surface of the polygon mirror. Done in. The laser beam L scanned in this manner is used as the product 3
When it hits the surface of the laser beam L, the laser beam L is diffusely reflected on this surface, and a part of the reflected light R is scanned / focused by the optical system 2.
Return to.

The scanning / focusing optical system 2 relays the reflected light R to the photodetector 4. The photodetector 4 uses the laser beam L
It is a photodiode covered with a filter that transmits only light having the same wavelength as (reflected light R), and inputs a current corresponding to a change in intensity of reflected light R to the binarization circuit 5.

The binarization circuit 5 converts the current value input from the photodetector 4 into a voltage value, compares the converted voltage value with a predetermined threshold value, and shapes the waveform into a square wave signal. To do. This square wave signal indicates “H” when the intensity of the reflected light R corresponds to the reflectance of the white bar in the barcode 3 a on the product 3, and the intensity of the reflected light R is the barcode on the product 3. When it corresponds to the reflectance of the black bar in 3a, "L" is shown. The binarization circuit 5 detects the rising edge (white edge) and the falling edge (black edge) of the square wave signal, outputs a white edge pulse (WEG) in synchronization with the white edge, and outputs the square edge signal to the black edge. Black edge pulse (BE
G) is output.

The bar width counter 6 is based on the white edge pulse (WEG) and the black edge pulse (BEG) input from the binarization circuit 5, and changes from the timing of the white edge pulse (WEG) to the black edge pulse (BEG). (Expected to correspond to the width of the white bar in the barcode 3a), and the time from the timing of the black edge pulse (BEG) to the timing of the white edge pulse (WEG) (the barcode 3a Expected to correspond to the width of the black bar inside). The bar width counter 6
Counts the number of clocks from the clock 7 in order to measure the time corresponding to these bar widths, and outputs the count value corresponding to these bar widths.

The filter circuit 8 logically judges each count value inputted from the bar width counter 6 and removes the counter value which clearly shows the intensity change due to a factor other than the reflected light R from the bar code 3a, This is a filter circuit that extracts only those that have a high probability of being the count value indicating the width of each bar of the barcode 3a and pass them to the next stage. The bar code 3a is scanned from the laser light source 1, the scanning / focusing optical system 2, the photodetector 4, the binarization circuit 5, the bar width counter 6, the clock 7, and the filter circuit 8, and the light and darkness on the scanning locus is scanned. Bright / dark pattern detection means for detecting the pattern row is configured.

The FIFO memory circuit 9 is a first-in first-out memory that temporarily holds the count values that have passed through the filter circuit 8 and outputs the count values in the order in which they are held, and functions as a buffer.

The bar code recognition / demodulation circuit 10 uses a FIF.
This is a processor that executes a predetermined recognition / demodulation program for each count value read from the O memory circuit 9 to take out various data encoded in the bar code.

Next, among these, the configurations of the FIFO memory circuit 9 and the bar code recognition / demodulation circuit 10 will be described in more detail. (FIFO Memory Circuit) FIG. 3 shows input / output signals of the FIFO memory circuit 9. In Figure 3, "BCD0-10"
Indicates a count value indicating the bar width output from the filter circuit 8. “B / W” is the filter circuit 8
The color identification signal indicates the bar color (white / black) output from. Each of these signals is sent from the filter circuit 8 to the SFTI.
When the N signal is transmitted, it is read by the FIFO memory circuit 9. Also, when reading these signals,
The FIFO memory circuit 9 receives the input ready signal (I
R) is sent to the bar width counter 6.

The FIFO memory circuit 9 and the bar code recognition / demodulation circuit 10 at the next stage are connected by a 16-bit external bus EB. Then, the FIFO memory circuit 9 outputs the earliest read bar width count value and color identification signal to the bar code recognition / demodulation circuit 10 via the external bus EB, and outputs an output instruction to instruct these information. A ready signal (OR) is issued to the barcode recognition / demodulation circuit 10. Then, when the bar code recognition / demodulation circuit 10 notifies the signal (SETOUT) indicating the completion of loading of these signals, the next bar width count value and color identification signal are directed to the bar code recognition / demodulation circuit 10. Output.

An external RAM 46 and an external ROM 47 are also connected to the external bus EB that connects the FIFO memory circuit 9 and the bar code recognition / demodulation circuit 10. The external RAM 46 is a random access memory that temporarily stores the data transmitted from the FIFO memory circuit 9. In addition, the external ROM 47 is the same as that shown in FIGS.
9 is a read-only memory for storing the program shown in FIG. 8 and the minimum valid data digit number table shown in FIG. (Bar Code Recognition / Demodulation Circuit) Next, the detailed configuration of the bar code recognition / demodulation circuit 10 will be described with reference to FIG.
The bar code recognition / demodulation circuit 10 includes a CPU 43 and an RA connected to a 32-bit internal bus LB.
M44, Universal Asynchronous Receiver
Transmitter (UART) 45, direct memory access controller (DMAC) 41, timer 42, and internal bus LB and external bus EB
Bus state controller (BS
C) 40.

The CPU 43 is composed of a RISC chip and controls the entire bar code recognition / demodulation circuit 10.
Further, with respect to the bar width count value and the color identification signal transmitted from the FIFO memory circuit 9, the minimum effective data digit number table shown in FIG. 8 is referred to and the barcode recognition shown in FIGS. 4 to 7 is performed. / Execute demodulation processing.

Bus state controller (BSC) 40
Is an input / output interface for managing the states of the internal bus LB and the external bus EB. The direct memory access controller (DMAC) 41 controls the bus state controller 40 when the signal (OR) instructing the signal acquisition from the FIFO memory circuit 9 is input, and the direct memory access controller (DMAC) 41 transmits the signal from the FIFO memory circuit 9. The received bar width count value and color identification signal are transferred to the CPU 43.
When this transfer is completed, the FIFO memory circuit 9 is notified of a signal (SETOUT) indicating the completion of signal acquisition.

The timer 42 is a device for generating time information used for various processes in the barcode recognition / demodulation circuit 10. A universal asynchronous receiver / transmitter (UART) 45 is a parallel / serial interface that converts the character information demodulated as parallel information into a serial signal and outputs the serial signal from an RS-232C port (not shown) to the outside.

Next, the contents of the bar code recognition / demodulation processing program executed by the CPU 43 will be described with reference to the flowcharts of FIGS. 4 to 7. The flowchart of FIG. 7 starts when the main power source is turned on to the barcode reading device. Then, in the first S001, initialization is performed. Here, for example, in accordance with a setting by a dip switch (not shown), the number of digits (reading digit number information) of the characters forming the barcode to be read by this barcode reading device is set (corresponding to character number specifying means). ).

At the next step S002, the most of the data strings stored in the external RAM 46 (corresponding to a series of count value strings, color identification signal strings, and light / dark pattern data strings read by one-way bar code scanning). Check if the old one contains the start bar (first bar). And when the start bar is detected,
It is assumed that this data string is likely to be based on the reflected light from the barcode, and the process proceeds to S004. On the other hand, when the start bar is not detected, it is checked in S003 whether the same data string includes the end bar (second bar). Then, when the end bar is detected, it is determined that this data string is highly likely to be based on the reflected light from the barcode, and the processing is performed in S004.
Proceed to. On the other hand, when the end bar is not detected, it is considered that the data is based on the reflected light from a portion other than the barcode, the data string is discarded, and the process returns to S002.

In S004, the length of the character adjacent to the bar (the start bar if the process comes directly from S002, the end bar if the process comes in from S003) is the standard condition of the predetermined bar code. Check whether or not Then, if the length of this character does not satisfy the predetermined standard condition, it is considered that this data string is data based on the reflected light from a position other than the barcode, and this data string is discarded and processed. Return to S002.

On the other hand, when the length of the character satisfies the predetermined standard condition, in S005,
This character is converted into corresponding data (corresponding to data conversion means for dividing the bright / dark pattern data string for each character and converting it into corresponding data of another format).

In the next step S006, it is checked whether or not the length of the character adjacent to the character converted into the data in step S005 satisfies the standard condition of the predetermined bar code. Then, if the length of this character does not satisfy the predetermined standard condition, the process proceeds to S009.

On the other hand, when the length of the character satisfies the predetermined standard condition, in S007,
This character is converted into corresponding data (corresponding to data conversion means), and in next S008, S005 or S
It is checked whether the data demodulation of 007 has been performed well. If the demodulation is unsuccessful, the process proceeds to 009, and if the demodulation is good, the process is S
Proceed to 011.

In S011, it is checked whether or not the adjacent character is the end bar. Then, when the adjacent character does not satisfy the configuration of the end bar, the processing is returned to S006. On the other hand, when the end bar is detected, it is determined that the barcode can be read all at once by continuous reading, and the process proceeds to S012.

On the other hand, in S009, based on the read digit number information set in S001, the minimum valid data digit number table shown in FIG. 8 is referred to and the corresponding "minimum valid data digit number" information is read. (Equivalent to the effective character digit number setting means). This "minimum number of valid data digits" is the minimum length (the number of character digits) necessary to handle each data string as valid when a barcode is synthesized based on two data strings. . As shown in FIGS. 10A and 10B, reading the barcode by dividing it into two data strings is called “division reading”.

In the minimum valid data digit number table of FIG. 8, the minimum valid data digit number is increased or decreased in substantially direct proportion to the size of the read digit number information (digit number of the entire bar code). This is because the data due to the erroneous reading is excluded and the barcode is synthesized only from the data string having a high probability due to the reflected light from the barcode. That is, the data sequence A and the data sequence B obtained by reading the barcode separately in the barcode 1 and the barcode 2 shown in FIG.
Since the bar code is obtained by reading 1/3 or more, it is unlikely that the data string from the part other than the bar code will have the same form by accident, but the data string A in the bar code 3 is
Since it is less than 1/3, there is a high possibility that the data string from the part other than the barcode will have the same form by chance. Therefore, the minimum valid data digit number is increased or decreased according to the read digit number.

In the next S010, the number of digits (number of characters) of the demodulated data string at this point in this data string.
"Minimum number of valid data digits" read in S009
Check if greater than. If the number of digits (number of characters) of the demodulated data string is less than the minimum number of valid data digits, the data string that is likely to have the same form as the data string from the barcode by chance is excluded and the data is removed. In order to prevent misreading, this data string is discarded and the process proceeds to S0.
The value is returned to 02 (corresponding to a discarding means for discarding the light / dark pattern data string having the number of characters less than the effective number of characters). On the other hand, if the number of digits (the number of characters) of the demodulated data string is larger than the minimum number of valid data digits, it is highly possible that the data string is obtained by dividing the barcode and read. Proceed to S012.

In S012, the barcode combining processing subroutine shown in FIG. 5 is executed. First S1 in FIG.
In 01, it is checked whether or not the demodulated data string that is the processing target in S012 is a data string obtained by scanning so as to pass only one of the start bar and the end bar. Then, in the case of the data string obtained by scanning so as to pass through both the start bar and the end bar, this is the case where the bar code is read all at once by continuous reading, so the variable i is set to "0" in S111. To reset the routine to end this subroutine.

On the other hand, in the case of the data string obtained by scanning so that only one of the start bar and the end bar passes, in S102, the demodulated data string is scanned so as to pass the start bar. Check whether it is the data string obtained by. If the data string has passed the start bar, the data string including the start bar (first light-dark pattern data string) is stored in the RAM 44 in S103, and if the data string has passed the end bar, , S104 stores a data string including the end bar (second light-dark pattern data string) in the RAM 44.

In any case, in the next step S105, it is checked whether or not the data sequence passing through the start bar and the data sequence passing through the end bar are aligned. Then, when the data strings passing through each bar are not yet complete, the process is returned to S002, and the demodulation process for the next data string is executed.

On the other hand, when the data strings passing through the respective bars are complete, the data digit number check subroutine shown in FIG. 6 is executed in S106. In the first step S201 in this data digit number check subroutine, the number of digits (number of characters) of the data string that has passed through the start bar.
And the number of digits (the number of characters) of the data string that has passed through the end bar are summed up (corresponding to the total sum calculation means). Next S20
In 2, it is checked whether or not the total sum added up in S201 exceeds the number of read digits set in S001 (corresponding to a comparison unit). When the sum is less than the number of read digits, there is no overlap between the data strings. Therefore, there is no guarantee that both data strings are data strings with the same bar code. Therefore, in order to eliminate erroneous reading of data, the process is returned to S002, and the demodulation process for another data string in place of the data string currently stored in the RAM 44 is executed. On the other hand, when the total sum exceeds the number of read digits, there is a high possibility that the data strings overlap each other. Therefore, this data digit number check subroutine is terminated, and the process returns to S106 of FIG. In S107 executed after S106, the data duplication part is checked.
This data duplication portion is a portion that is read in duplicate by each of the two data strings, as indicated by the shaded portion in FIG. That is, here, it is checked whether the data at the end portion of the data string passing through the start bar and the data at the end portion of the data string passing through the end bar match. The number of digits (the number of characters) of this data duplication part is equal to the number obtained by subtracting the number of read digits from the total number of digits of both data strings. If the result of this check is that there is no overlapping part, or if the number of digits in the overlapping part does not match the number obtained by subtracting the number of reading digits from the total number of digits in both data strings, then data other than data based on the same barcode is not used. On the assumption that the data is likely to be mixed, the process is returned to S002 in S108, and the demodulation process is performed on another data string in place of the data string currently stored in the RAM 44. On the other hand, if the number of digits in the overlapped portion matches the number obtained by subtracting the number of read digits from the total number of digits in both data strings, the process proceeds to S109. That is, these S1
From 06 to S108, the first overlapping part is the same data.
And the second bright / dark pattern data sequence are included in the overlapping portion determining means.

In S109, the matching number check subroutine shown in FIG. 7 is executed. The number of matching check subroutines is the number of read digits and the number of duplicated digits (number of characters)
According to the above, it is a process for varying the number of coincidences of the data of the overlapping part as the data synthesis execution condition. That is, FIG.
Since the number of read digits is different between the barcode 1 and the barcode 2 shown in FIG. 2, there is a difference in the ratio of the overlapping portion to the number of read digits. Then, when the ratio of the overlapping portion to the number of read digits is small like the barcode 2, there is a possibility that the overlapping portion of both data may be caused by erroneous reading. Therefore,
In such a case, the condition of the data combination is to perform the data demodulation again and to confirm the coincidence of the overlapping part data again. Similarly, since the bar code 2 and the bar code 3 shown in FIG.
There is a difference in the ratio of the duplicated portion to the number of read digits. When the ratio of the overlapping portion to the number of read digits is large like the barcode 3, the possibility that the overlapping portion of both data is caused by erroneous reading becomes low. Therefore, in such a case, the condition for data composition is only that the coincidence of the duplicated part data is confirmed this time.

When the subroutine for checking the number of coincidences is entered, the variable i indicating the number of coincidences of the data in the first S301 overlapped portion is incremented by one. The initial value of this variable i is 0.

In the next step S302, it is checked whether the number of read digits is 5 digits or less (corresponding to a threshold value setting means). If the number of digits is 5 or less, in S303, it is checked whether or not the number of digits of the overlapping portion is 3 or more (corresponding to a comparison unit). If the result of this check is that the number of digits in the duplicated portion is three or more, the process proceeds to S307 and 3
If it is less than the digit, the process proceeds to S308.

On the other hand, the number of read digits is 5 in S302.
When it is determined that the number of digits exceeds the number of digits, it is checked in S304 whether the number of read digits is 10 digits or less (corresponding to a threshold value setting means). If it is 10 digits or less, in S305, it is checked whether the number of digits of the overlapping portion is 4 digits or more (corresponding to a comparison unit). As a result of this check, if the number of digits of the overlapping part is 4 digits or more, the process proceeds to S307, and if it is less than 4 digits, the process proceeds to S308. On the other hand, if the number of read digits exceeds 10, then S
At 306, it is checked whether the number of digits of the overlapping portion is 5 digits or more (corresponding to a comparison unit). As a result of this check, if the number of digits of the overlapping portion is 5 or more, the processing is performed in S307.
If it is less than 5 digits, the process proceeds to S308.

In S307, the reference value k is set to "1". Further, in S308, the reference value k is set to "2". In any case, in the next step S309, the matching number i at the present time is compared with the reference value k. If the matching count i is less than the reference value k, the process returns to S002 in order to demodulate the data string again and reconfirm the matching of the data. In this case, while holding the value of the variable i, the RAM
The data string stored in 44 is cleared, and the newly demodulated data string is stored (the judgment by the overlapping part judging means is determined by the first bright-dark pattern data string newly detected by the light-dark pattern detecting means and the first light-dark pattern data string). (Corresponding to the judgment re-execution means to be executed with respect to the light-dark pattern data sequence 2).
On the other hand, if the matching count i is equal to or greater than the reference value k, it is confirmed that the data duplication part is not likely to be misread, and the possibility of data misreading is reduced. The check subroutine is terminated and the process returns to FIG. As a result, the larger the number of digits to be read, the larger the number of digits of the overlapping portion that allows confirmation of coincidence of the overlapping portion only once.

In the barcode synthesizing subroutine of FIG. 5 to which the processing is returned, the synthesizing of data is executed in S110 executed after S109. That is, the overlapping portion of the data string passing through the start bar and the portion following the overlapping portion of the data string passing through the end bar are combined to synthesize a series of data strings corresponding to the entire barcode (first It corresponds to a combining means for combining the light-dark pattern data string and the second light-dark pattern data string). The data string synthesized in this way has the same structure as the data string read all at once by continuous reading.

In the next step S111, since the synthesis of one bar code is completed, the variable i is reset to 0 in preparation for the reading of the next bar code. After this, this barcode synthesis subroutine is terminated and the processing returns to FIG.

In the main routine of FIG. 4 in which the processing is returned, data transmission is executed in S013 executed after S012. That is, the data string stored in the RAM 44 (the data string read at a stretch by continuous reading, or the data string synthesized in S012) is
Transmits to the outside via a universal asynchronous receiver transmitter (UART) 45. Then, in order to read the next bar code, the process returns to S002.

According to the bar code reader having the above-described structure according to the present embodiment, since it includes only one of the start bar and the end bar, it cannot be immediately regarded as the data string based on the bar code. By checking the data contents of the overlapping portions even for the divided read data string, it is possible to combine them as a series of data strings based on one bar code. This overlapping portion can be easily extracted by specifying the number of digits to be read of the barcode and only calculating the total number of digits of the data string for divided reading.

A data string of each divided reading (a data string including only one of the start bar and the end bar)
Has undergone screening based on the minimum number of effective data digits in advance (S010), so only those with a number of digits greater than this minimum effective data digit number will be erroneously read based on the reflected light from a portion other than the barcode. There is less room for data to be mixed. Since the minimum number of valid data digits is determined in direct proportion to the number of read digits (S009), data combination is performed only from a data string having sufficient reliability in relation to the number of digits of the barcode. be able to.

Further, in checking the data content of the overlapping part of the divided read data string, the number of passes required for data combination changes depending on the number of read digits and the number of digits of the overlapping part ( S309). That is, when the number of digits in the overlapping portion is the same, and the number of digits to be read becomes large, the number of passes required for data combination becomes twice. Further, if the number of read digits is the same, and the number of digits in the overlapped portion becomes smaller, the number of passes required for data combination becomes twice. Therefore, the number of reading digits and the number of digits in the overlapped portion are changed to increase the reliability of data combination by varying the number of checks, so there is room for misreading data based on the reflected light from the portion other than the barcode. Becomes smaller.

[Embodiment 2] In the first embodiment, regardless of the number of read digits, it is sufficient that the total sum of both data strings in divided reading exceeds the number of read digits (S20).
2). Therefore, the number of digits in the overlapping part should be at least 1,
Only afterwards, in the matching count check of FIG. 7, only the number of passes of the data contents of the overlapping part necessary for data composition was changed according to the number of digits of this overlapping part.

The second embodiment is characterized in that the number of digits required for the overlapped portion is changed according to the size of the number of read digits. FIG. 14 is an external RO in the second embodiment.
The composite digit number table stored in M47 (see FIG. 3) is shown. As is apparent from FIG. 14, when the number of read digits increases, the “combined number of digits” increases in almost direct proportion. This "composite digit number" defines the lower limit of the sum of the number of digits of data that has passed through the start bar and the number of digits of data that has passed through the end bar. Therefore, when the number of read digits increases, the number of digits of the overlapping portion increases in almost direct proportion.

FIG. 13 is a flow chart showing a data digit number check subroutine executed in S106 of FIG. 5 to check the number of digits in the overlapped portion by referring to the composite digit number table. 6 corresponds to the flowchart of FIG. In the first step S401 after entering this data digit number check subroutine, S001
Based on the number of read digits set in (4), the combined digit number table of FIG. 14 is referred to, and the combined digit number information corresponding to the read digit number is read (corresponding to the combined digit number setting means).

In the next step S402, the number of digits (the number of characters) of the data string that has passed the start bar and the number of digits (the number of characters) of the data string that has passed the end bar are summed up (corresponding to the total sum calculation means). In the next step S403, it is checked whether or not the total sum added up in step S402 exceeds the combined digit number read in step S401 (corresponding to a comparison unit). If this total is less than or equal to the number of read digits, there is no overlap between the data strings, or the number of digits in the overlapped portion is insufficient compared to the number of read digits. Therefore, even if the data in the overlapping parts match each other, it cannot be denied that they may just match by chance. Therefore, in order to eliminate erroneous reading of data, the process is returned to S002, and the demodulation process for another data string in place of the data string currently stored in the RAM 44 is executed. On the other hand, when the total sum exceeds the combined digit number, the overlapping part has a digit number such that the data cannot coincide with each other by chance. Therefore, the subroutine for checking the number of data digits is completed, and S in FIG.
Return to 106.

As described above, in the second embodiment, the number of digits of the overlapped portion which requires the matching of the data contents is changed according to the size of the number of read digits (S401). Therefore, the data combination can be performed only from the data string having sufficient reliability in relation to the number of digits of the barcode. That is, the barcode 1 and the barcode 2 shown in FIG.
Even if the number of digits of the overlapping portion is the same, the number of digits of the entire barcode is different, and therefore the ratio of the overlapping portion to the entire barcode is different. That is, the ratio of the overlapping part in the barcode 2 is smaller than the ratio of the overlapping part in the barcode 1. Therefore, even if there is no erroneous reading of data in the barcode 1, there is a high possibility that the data in the barcode 2 will only coincide by chance due to erroneous reading of the data in the overlapping portion. Therefore, in that case, as shown by the barcode 3, the number of digits required for the overlapping portion is increased so that the data in the overlapping portion do not coincide with each other by accident.

The other hardware configuration and processing contents in the second embodiment are the same as those in the first embodiment, and therefore their explanations are omitted.

[0072]

According to the barcode reading apparatus and the barcode reading method of the present invention configured as described above, the first bright-dark pattern data string including the first bar but not the second bar, and , The second light-dark pattern data string including the second bar but not the first bar is connected to each other only when both have an overlapping portion formed of the same data. As a result, erroneous reading of data can be suppressed as much as possible, and it is possible to synthesize read data of the entire barcode based on these data strings. Therefore, it becomes possible to complete the reading of the bar code in a short time without requiring frequent correction in the scanning direction.

[Brief description of drawings]

FIG. 1 is a principle diagram showing the principle of the present invention.

FIG. 2 is a block diagram of a barcode reader according to the first embodiment of the present invention.

3 is a block diagram showing a detailed configuration of a FIFO memory circuit and a barcode recognition / demodulation circuit of FIG.

4 is a flowchart showing the contents of a barcode recognition / demodulation processing program executed by the CPU of FIG.

FIG. 5 is a flowchart showing the contents of a barcode synthesis subroutine executed in S012 of FIG.

FIG. 6 is a flowchart showing the contents of a data digit number check subroutine executed in S106 of FIG.

FIG. 7 is a flowchart showing the contents of a match count check subroutine executed in S109 of FIG.

8 is a diagram showing a minimum valid data digit number table stored in the external RAM shown in FIG. 3;

FIG. 9 is a diagram showing the configuration of a second code.

FIG. 10 is a diagram showing a scanning direction for reading a second code.

FIG. 11 is an explanatory diagram of the relationship between the number of read digits and the minimum valid data.

FIG. 12 is an explanatory diagram of the relationship between the number of digits to be read and the number of digits in the overlapping part.

FIG. 13 shows S1 of FIG. 5 in the second embodiment of the present invention.
Flowchart showing contents of data digit number check subroutine executed in 06

FIG. 14 is a diagram showing a combined digit number table stored in the external RAM of FIG. 3 in the second embodiment of the present invention.

FIG. 15 is a flowchart showing the contents of a barcode recognition / demodulation processing program executed by a conventional barcode reader.

[Explanation of symbols]

1 laser light source 2 scanning / focusing optical system 3a barcode 4 Light detector 5 Binarization circuit 6-bar width counter 8 filter circuits 10 Bar code recognition / demodulation circuit 43 CPU 44 RAM 47 External ROM

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Isao Iwaguchi             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited (72) Inventor Ichiro Shinoda             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited F term (reference) 5B072 AA01 AA02 CC24 DD01 DD02                       EE11 FF02 FF33 LL01 LL12                       LL20

Claims (4)

[Claims] 1. A light / dark pattern detecting means for scanning a bar code whose both ends are sandwiched by a first bar and a second bar to detect a light / dark pattern data string in a scanning locus, and the light / dark pattern detecting means. Data conversion means for dividing the detected light-dark pattern data sequence into characters corresponding to the other data and converting the data into other corresponding data, and the data conversion including the first bar but not the second bar. The first light-dark pattern data string converted by the means and the second light-dark pattern data string including the second bar but not the first bar are converted into the light-dark pattern data. When detected by the means, an overlapping portion composed of the same data overlaps the first light-dark pattern data string and the second light-dark pattern data string. And an overlapping portion determining unit that determines whether or not the overlapping portion is included in each of the first light-dark pattern data sequence and the second light-dark pattern data sequence. The first light-dark pattern data string and the second light-dark pattern data string are combined, a threshold setting unit that presets a threshold value for the number of characters in the overlapping portion, The number of characters in the overlapping portion included in each of the first light and dark pattern data string and the second light and dark pattern data string is smaller than the threshold value is compared, and the number of characters in the overlapping portion is the threshold value. A comparison unit that completes reading of the first light-dark pattern data string and the second light-dark pattern data string when the above is satisfied, and the comparison result by the comparison unit, When the number of characters in the multiple part is less than the threshold value, the first bright / dark pattern data string and the second bright / dark pattern newly detected by the bright / dark pattern detecting means are newly determined by the overlapping portion determining means. And a determination re-execution unit for executing the pattern data sequence. 2. The bar code reading device according to claim 1, further comprising a character number specifying means for specifying the number of characters of the bar code to be read. 3. The threshold value setting means sets the number of characters of the threshold value larger as the number of characters specified by the character number specifying means increases. Bar code reader. 4. When the threshold value setting means determines that the first light-dark pattern data string and the second light-dark pattern data string include an overlapping portion, the number of times the pattern strings match each other. Is increased by one, and the comparison unit compares the number of characters in the overlapping portion with each other, and when the result is equal to or more than the threshold value, the reference value is 1, and when the number is less than the threshold value, the reference value is 2. When the number of matches is greater than or equal to a reference value, the reading is completed, and when the number of matches is less than the reference value, the determination execution means is configured to set the threshold value. 4. The bar code reading device according to claim 1, wherein the determination by the means and the comparison by the comparison means are executed again.