JP2903792B2 - Barcode reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader which measures the width of a bar and space pattern of bar code information, sequentially analyzes a character pattern based on the measurement result, and reads the character.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for decoding UPC-based and EAN-based bar codes, for example, Japanese Patent Application Laid-Open No. 60-108
An apparatus described in Japanese Patent No. 978 is known. In the conventional device, the barcode is read as follows.
FIG. 2 is an enlarged view of a main part of the barcode. First, the widths b, c, d, and e of two spaces and two bars representing one character are measured. Then, the character is determined from the sum of the width c of the first bar and the width d of the second space, and the sum of the width d of the second space and the width e of the second bar. However, this technique alone cannot distinguish between the number “1” and the number “7”, and further cannot distinguish between the number “2” and the number “8”. Therefore, if these indistinguishable numbers are listed as candidates in the conventional device, one more
From the sum (b + d) of the widths of the second space and the second space,
By subtracting the sum (c + e) of the widths of the first and second bars and comparing the subtracted value with a threshold value, it is possible to determine the numbers “1” and “2” or to determine the numbers “7” and “8”. "Can be determined.

[0003]

However, the above-mentioned conventional apparatus has a problem that erroneous reading occurs due to thickening or thinning of a bar or space caused by bleeding or the like when printing a barcode. That is, the width c, e of each bar
Is larger than the nominal value on both sides by Δ3, Δ4, Δ5, and Δ6, respectively, the subtraction value to be compared with the predetermined threshold value is 2 × (Δ3 + Δ
4 + Δ5 + Δ6).
Therefore, erroneous reading may occur depending on the magnitude of Δn.

An object of the present invention is to solve the above-mentioned problems and to eliminate the possibility of erroneous reading caused by a thick or thin bar or space.

[0005]

As shown in FIG. 1, a bar code reader according to the present invention has a measuring means for measuring the width of a bar and space pattern of bar code information, and the measuring means comprises: Analyzing means for sequentially analyzing a plurality of character patterns constituting the pattern arrangement based on the measured result and reading the character indicated by each character pattern; and reading means for reading the barcode information by the character read by the analyzing means. And a bar code reading apparatus comprising: a plurality of candidate characters for the decoding target character pattern as a result of the analysis by the analysis unit; The measured value of the width and the one immediately before the character pattern to be decoded
A subtraction value calculating means for adding a measured value of the width of the pattern and calculating a subtraction value obtained by subtracting the nominal value of the width of the immediately preceding pattern from the added value; First one of each character pattern
A character pattern whose nominal value of the book pattern is close to the subtraction value is selected, a character corresponding to the selected character pattern is read as a character indicated by the character pattern to be decoded, and the selected character is read by the reading means. And character selecting means for outputting a character.

In the above arrangement, the measuring means measures the width of the bar and space pattern of the bar code information. Then, based on the result measured by the measuring means, the analyzing means sequentially analyzes a plurality of character patterns constituting the pattern arrangement and interprets the character indicated by each character pattern.

Various well-known techniques are used as an analysis technique in the analysis means. For example, the method described in the related art is used. As a result of the analysis by the known method, a plurality of candidate characters may be listed for the character pattern to be decoded. According to the method described in the related art, the number “1” and the number “7” cannot be distinguished from each other and are both considered as candidate characters. Similarly, the numeral “2” and the numeral “8” are both candidates.

When a plurality of candidate characters are listed, the subtraction value calculation means calculates the measured value of the width of the first one of the character patterns to be decoded and the one immediately before the character pattern to be decoded. The measured value of the width of the pattern of the book is added, and the one
A subtraction value is calculated by subtracting the nominal value of the width of the book pattern. Here, the subtraction value calculated by the subtraction value calculation means will be described with reference to FIG. As shown in FIG. 2, each bar and each space are thick and thin. There are thick components Δ1 to Δ6 (or thin components) on both sides of each bar a, c, e.
Generally, such thickening or thinning occurs due to the habit of a printing machine or the like, and thus the thickening component Δ of each of the bars a, c, and e.
The width of 1, Δ3, Δ5 (or the narrow component) is substantially equal. Therefore, a subtraction value obtained by subtracting the nominal value A of the immediately preceding pattern from the sum (a + b) obtained by adding the first one pattern b of the character pattern to be decoded and the immediately preceding pattern a is: , (A + b) −A = (Δ1 + A + Δ2 + b) −A = Δ1 + Δ2 + b ≒ Δ2 + b + Δ3 This is the measured value of the first pattern of the character pattern to be decoded, that is, the value obtained by adding the thick components (or thin components) Δ2 and Δ3 to the width b of the space to compensate for the effect of the thin (or thick). This value is sufficiently close to the nominal value B of this space.

The character selection means selects a character pattern in which the nominal value of the first one of the character patterns corresponding to the candidate character is close to the subtraction value, and selects a character corresponding to the selected character pattern. It is interpreted as a character indicated by the character pattern to be decoded. Then, the selected character is output to the reading means. The reading means reads bar code information by the character. Since the subtraction value is a value sufficiently close to the nominal value as described above, by reading the approximation with the nominal value in this way, it is possible to perform high-precision reading without the influence of the thickening or thinning of the bar or space. .

[0010]

An embodiment of the present invention will be described below. FIG. 3 is a block diagram of a main part of the barcode reading device according to the embodiment. The bar code reader includes a central processing unit 1, a sensor output signal processing circuit 3, a CCD image sensor 5, a sensor driving circuit 7, an optical system 9, an LED 11, an LED
It includes a drive circuit 13, an interface circuit 15, and the like. The central processing unit 1 is a computer mainly including a CPU, a ROM, a RAM, and the like. The ROM previously stores software for various processes to be described later, a table referred to in the reading process, and the like. CPU 1 by executing the software, the control of the peripheral circuits, and performs such as a bar code width counting and analysis of the bar code B of the B. The analyzed data is output to an external device such as a POS (corresponding to a reading unit) via the interface circuit 15.
The sensor output signal processing circuit 3 amplifies the output signal of the CCD image sensor 5 and converts the output signal into a digital signal. The optical system 9 includes a lens, a mirror, an aperture, and the like, and forms an image of the barcode B on the CCD image sensor 5.
The LED 11 is a light source for illuminating the bar code B.
Driven by the ED drive circuit 13.

The central processing unit 1 includes an LED driving circuit 1
3 and the sensor drive circuit 3 to capture the bar and space width data of the bar code B from the sensor output signal processing device 3, and analyze the bar code as follows. As an example of the barcode analysis processing, the decoding of a character on the left side of the center bar will be described below.

When the CPU of the central processing unit starts the decoding processing routine (FIG. 4), first, the measurement processing of the bar code measurement elements a, b, c, d, and e (S100, S11).
0, S120, S130, S140). The measurement element a is the width of one bar immediately before the character pattern to be decoded. The nominal value of the width of one of the bars just before this is A. Measuring elements b, c, d,
e is the measured value of the first space, the measured value of the first bar, the measured value of the second space, and the measured value of the second bar of the character pattern to be decoded.

Next, the comparison values M1 and M2 are calculated (S1
50, S160). The sum of the measured value of the width of the first bar and the measured value of the width of the second space is set as the comparison value M1 (S150). The sum of the measured value of the width of the second space and the measured value of the width of the second bar is set as the determination value M2 (S160).

Next, the comparison values M1 and M2 are determined by a known method (S170), and the comparison values M1 and M2 are set to the numbers "1,"
If it is determined that the character is a character other than "2, 7, 8", a determination process for that character is executed (S180). on the other hand,
When it is determined that the comparison values M1 and M2 are either the number “1” and the number “7” or the number “2” and the number “8” (S170), the processing of calculating the comparison value M4 in any case. Is executed (S190, S200). The comparison value M4 is set to a value obtained by subtracting the nominal value A of the immediately preceding bar from the sum of the measured value a of the immediately preceding bar and the measured value b of the first space. Is done.

Next, the comparison value M4 is compared with the threshold value S (S210, S220). The threshold value S is set in advance as shown in Table 1 and stored in the ROM.

[0016]

[Table 1]

For example, this decoding processing routine (FIG. 4) targets a character on the left side of the center bar. Assuming that ODD parity is set on the left side of the center bar, when determining the number “2” and the number “8”, the threshold value S = 1.5 is compared with the comparison value M4 (S21).
0). If the comparison value M4 is smaller than the threshold value S (S21
0), the process of setting the number "8" (S240) is executed, and if M4 is equal to or larger than the threshold value S (S210), the process of setting the number "2" (S230) is executed, and this routine is executed. To end. On the other hand, when determining the number “1” and the number “7”, the threshold value S = 1.5 is compared with the value of M4 (S220). If M4 is smaller than the threshold value S (S220), the process of setting the number "7" (S2)
60), and if M4 is greater than or equal to the threshold value S (S2
20), the process of setting the number “1” (S250) is executed, and this routine ends.

That is, when the numbers “2” and “8” cannot be determined, or when the numbers “1” and “7” cannot be determined, the measurement of one bar immediately before the character pattern to be decoded is performed. By using the value and the nominal value, the determination of the numbers “2” and “8” or the numbers “1” and “7” is performed. An example of this embodiment will be described below with reference to FIG. There are thick components (or thin components) Δ1 to Δ6 on both sides of each bar a, c, e. As described above, since such thickening or thinning generally occurs due to the habit of a printing machine or the like, the widths of thickening components (or thinning components) Δ1, Δ3, and Δ5 of the bars a, c, and e are substantially equal. Therefore, the comparison value M4 calculated in steps S190 and S200 of the decoding processing routine is very close to the nominal value of the first space of the character pattern to be determined from now, as shown in the following equation.

M4 = (a + b) −A = (Δ1 + A + Δ2 + b) −A = Δ1 + Δ2 + b ≒ Δ2 + b + Δ3 = B The nominal value B of the first space of the character pattern is
As shown in Table 1, each number differs. Therefore, by comparing the threshold value for distinguishing between the nominal values B of the candidate characters with the above-mentioned M4, the numbers “1”, “7”, “2”, “2”, which cannot be determined from the comparison values M1 and M2. 8 "
Can be read without being affected by the weight and thickness of the bars and spaces.

It should be noted that the nominal value A of one bar immediately before being used in the above processing is obtained as follows. The pattern immediately before the character pattern to be decoded includes
There are three types: guard bar, center bar, and character. In the following, a process for obtaining a nominal value according to the type of the immediately preceding pattern will be described. Here, the read code type is EAN-
13. The decoding direction is one direction from the left guard bar to the right guard bar. Of course, other UPC, EA
The N code and other decoding directions are decoded in the same manner.

FIG. 5 shows a left guard bar nominal value setting processing routine, FIG. 6 shows a character pattern nominal value setting processing routine, FIG. 7 shows a center bar nominal value setting processing routine, and FIG.
9 shows a flowchart of the right guard bar determination processing routine. At the time of reading a barcode, since the decoding direction is one direction from the left side to the right side, first, the left guard bar nominal value setting processing routine of FIG. 5 is started.

When the routine is started, a margin is searched first (S300). Then, the width of each of the next two bars of the margin and one space sandwiched between the bars is measured, and the measured values are added, and the added value is set as a variable J (S310). Next, the width of each of the two spaces and the two bars immediately after the measurement object measured in step S310 is measured, the measured values are added, and the added value is set as a variable K (S320).

Next, it is determined whether or not the value of the variable J falls within a range obtained by substituting the variable K into a predetermined formula (S33).
0), if fit, 1 sandwiched between the first two bars
It is determined that the book space is a guard bar (S34)
0). Then, the nominal value of the second guard bar is set to 1
The module is set as a module (S350), and this routine ends.
If the variable J does not fall within the predetermined range (S330),
It is determined that the code is not the EAN-13 code (S360), and this routine ends.

As described above, the nominal value of the second guard bar is obtained. The obtained nominal value is used at the time of decoding the first character pattern following the guard bar when executing the above-described decoding processing routine (FIG. 3). Next, a description will be given of a character pattern nominal value setting processing routine (FIG. 6) which is activated when decoding a character subsequent to the first character.

When the routine (FIG. 6) is started, first,
The character determined by executing the preceding decoding process routine (FIG. 4) is read (S400). Then, the nominal value of the last bar of the character is read from the table (Tables 2 and 3) stored in the ROM in advance, and is set as the nominal value of the bar immediately before decoding the next character. (S410). As shown in Tables 2 and 3, the nominal value is specified from three types of conditions: the position of the character (left or right of the center bar), the type of parity, and the character.

[0026]

[Table 2]

[0027]

[Table 3]

As described above, the nominal value of the last bar of the character pattern immediately before the character pattern to be decoded is obtained. The obtained nominal value is used at the time of executing the above-described decoding processing routine (FIG. 4). While the determination of the characters is progressing by executing the above-described routines, the center bar nominal value setting processing routine (FIG. 7) is started when the sixth character is determined. When the center bar nominal value setting processing routine is started, first, the two space values of the sixth character pattern and the measured values of the widths of the two bars are added, and the added value is set in a variable M ( S500). The width of each of the three spaces and the two bars following the sixth character pattern is measured, the measured values are added, and the added value is set as a variable N (S510).

Next, it is determined whether or not the variable M falls within a range obtained by substituting the variable N into a predetermined equation (S520). If the variable M falls within the range, the three spaces and the two bars are replaced by the center bar. It is determined that there is (S530), and the last space out of the five
The nominal value of the scan was a 1 module (S540), and terminates this routine. If the variable M does not fall within the predetermined range (S520), it is determined that the code is not an EAN-13 code (S550), and the routine ends.

As described above, the nominal value of the last space of the center bar is obtained. The obtained nominal value is used at the time of executing the above-described decoding processing routine (FIG. 4). The execution of each of the above-described routines advances the determination of the character. When the sixth character from the center bar is determined, the right guard bar determination processing routine (FIG. 8) is started.

First, two spaces and two bars of the sixth character pattern from the center bar are measured, and an added value obtained by adding the measured values is set as a variable X (S600). Next, two bars following the sixth character pattern from the center bar and one space between them are measured, and an added value obtained by adding the measured values is a variable Y
(S610).

Next, it is determined whether or not the value of X falls within a range obtained by substituting Y into a predetermined formula (S620). If it does, two bars and one space between them are located on the right. It is determined that it is a guard bar (S630), and this routine ends. If the variable X does not fall within the predetermined range (S62)
0), it is determined that the code is not the EAN-13 code (S65).
0), end this routine.

According to the bar code reader described above,
When reading the numbers "1" and "7" or the numbers "2" and "8", the thickening or thinning of the bar and the space has almost no effect, so that the risk of erroneous reading is extremely small and the reading accuracy of the bar code reading device is improved. Is achieved.

Although the embodiment has been described above, the present invention is not limited to the embodiment at all, and it goes without saying that the present invention can be implemented in various modes without departing from the spirit of the present invention. For example, a laser or an incandescent bulb may be used as a light source for irradiating a bar code with light. In configurations used in sufficiently bright locations, the light source is not essential. Further, as the optical sensor, a one-dimensional sensor such as a MOS sensor may be used in addition to the CCD image sensor. Further, a one-element photosensor used in a pen scanner or a laser scanner may be used. In this case, the barcode must be scanned, but the scanning may be performed manually or may be automatically performed using a motor or the like. Further, when the sensor is brought into close contact with or close to the barcode, the optical system 9 is not essential. In the embodiment, the decoding order is performed in one direction from the left guard bar to the right guard bar. However, the decoding order may be sequentially performed from the center bar to the guard bar. Further, the decoding may be performed sequentially from the right guard bar to the left guard bar. The subtraction value is compared with a threshold value (S21).
0, 220), besides the configuration for selecting a character, for example, a configuration may be adopted in which a subtracted value is selected for a character having a nominal value that is smaller than the nominal value corresponding to a candidate character. There are various methods for determining the guard bar and the center bar other than the embodiment, and any of them may be used.

[0035]

According to the bar code reader described above, since the thickness and width of the bar and the space hardly affect the reading, the risk of erroneous reading is extremely small, and the reading accuracy of the bar code reader is improved. This has the effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a basic configuration of the present invention.

FIG. 2 is an explanatory diagram for explaining a reading principle.

FIG. 3 is a block diagram of a bar code reader according to one embodiment of the present invention.

FIG. 4 is a flowchart of a decoding processing routine executed in a central processing unit of the barcode reading device.

FIG. 5 shows EAN-13 executed in the central processing unit.
5 is a flowchart of a left guard bar nominal value setting processing routine in FIG.

FIG. 6 is a character pattern nominal value setting processing routine executed in the central processing unit.

FIG. 7 shows EAN-13 executed in the central processing unit.
7 is a flowchart of a center bar nominal value setting processing routine in FIG.

FIG. 8 shows EAN-13 executed in the central processing unit.
9 is a flowchart of a right guard bar determination processing routine in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Central processing unit, 3 ... Sensor output signal processing circuit, 5 ... CCD image sensor, 9 ... Optical system, 11 ... LED, B ... Bar code

Claims (1)

(57) [Claims] 1. A measuring means for measuring the width of a bar and space pattern of bar code information, and a plurality of character patterns constituting the pattern arrangement are sequentially analyzed based on a result measured by the measuring means for each character. In a bar code reading apparatus comprising: analysis means for reading a character indicated by a pattern; and reading means for reading the bar code information by the character read by the analysis means, the result of the analysis by the analysis means, a character pattern to be decoded When a plurality of candidate characters are listed, the measured value of the width of the first pattern of the character pattern to be decoded and the measurement of the width of the single pattern immediately before the character pattern to be decoded And a nominal value of the width of the immediately preceding pattern is calculated from the added value. Subtraction value calculation means for calculating the calculated subtraction value; and selecting a character pattern in which the nominal value of the first one of the character patterns corresponding to the candidate character is similar to the subtraction value. The corresponding character of the character pattern is interpreted as a character indicated by the character pattern to be decoded,
A bar code reader comprising: a character selecting unit that outputs the selected character to the reading unit.