JPH04100188A - Bar code reader - Google Patents

Abstract

PURPOSE:To preclude a misread due to a noise without decreasing a read rate by inputting demodulated data which has an identification flag to a check part at least twice and checking the data as demodulation data of a block when a match is obtained. CONSTITUTION:A demodulation part 11 passes the demodulated data 20 to the check part together with an added identification flag 21 when detecting a right or left guard bar LGB or RGB in a serial electric signal inputted by repeatedly scanning a bar code label 15 and starting demodulation, the identification flag 21 is added to the demodulated data 20 and the data 20 is gived to a check part 10. The check part 10 when inputting the demodulated data 20 together with the identification flag 21, inputs the data at least twice, and checks the demodulated data 20 as demodulation data 20 of one block when the data are equal. Consequently, the read rate is increased and a misread can be prevented.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a barcode reading device, and an object of the present invention is to prevent misreading due to noise without reducing the reading rate. A scanning section that repeatedly scans the divided barcode labels and converts the reflected light into electrical signals, a demodulation section that demodulates the barcode for each left and right block based on the electrical signal, and a demodulation section that demodulates the demodulated data of the left and right blocks. and a check unit for checking the normality of combining and reading, and the demodulating unit includes:
An identification flag is attached to the demodulated data obtained by scanning from the left guard bar toward the center bar or from the right guard bar toward the center bar, and inputted to the checking unit, and the checking unit determines that the demodulated data with the identification flag is at least The configuration is such that when the data is input twice and they match, it is checked as demodulated data of the 8-block.

[Industrial application field]

The present invention relates to improvements in barcode reading devices.

There are white areas on the left and right sides of the barcode as margins, and if noise is picked up in these areas, there is a risk of misreading depending on the scanning direction.

In order to prevent this misreading, in a reading device that scans the label multiple times, it is sufficient to match all the data, but the reading rate decreases.

Therefore, there is a need to prevent misreading due to noise without reducing the reading rate.

[Conventional technology]

FIG. 5 is a diagram explaining the prior art, and FIG. 6 is a diagram showing an example of bit shift due to noise.

As shown in Figure 5, barcodes used in PO3 terminals, etc. are separated by left guard bar LGB, center bar CB, and right guard bar RGB.
-CB), (CB-RGB) can be read even if half blocks are input at a time.

FIG. 5 shows an example of the configuration of a stationary barcode reading device using a laser beam, in which the scanning unit 1 repeatedly scans the barcode label 15 with the laser beam, and
The AD conversion circuit 2 receives the reflected beam and performs photoelectric conversion.
binarizes this converted signal, and the demodulator 11a demodulates each block.

The demodulated data 20 of the left and right blocks is sent to the checking unit 10.
The normality of the data is checked based on check digits included in the barcode, and if normal, the operator is notified and each demodulated data 20 is output to the main unit.

Note that in order to prevent misreading, the left and right blocks must be scanned at least twice each so that the demodulated data matches.
In addition, if the other checks are OK, the reading is OK (double match method), or if one block is scanned two or more times and the demodulated data matches, the other block is scanned once. Read OK even if 1
, 5-time matching method, etc. are used.

[Problem to be solved by the invention]

As shown in FIG. 5, the barcode label 15 is provided with white portions on the left and right sides as margins.

However, if this white part is long, paper surface noise is likely to be picked up due to unevenness of the paper surface, and depending on the scanning direction, a bit shift of the barcode may occur, resulting in misreading.

Figure 6 shows an example of a bit shift, and (II) is the AD conversion when scanning is performed in the direction A in Figure 5, that is, from LGB to CB, and noise 30 is acquired in the margin immediately before LBG. An example of binary data output from the circuit 2 is shown. According to this, the normal value (3030) of ODD shown in (1) is bit shifted and is misread as (6464) of ODD as shown in (n).

This bit shift tends to occur when scanning from a white part (LGB or RGB) in the CB force direction, that is, in the A direction or C direction in FIG. 5, and does not occur when scanning in the B direction or D direction.

This is due to the characteristics of the AD conversion circuit 2, such as the fact that if the white portion is long, the slice level for noise removal is lowered.

In order to prevent misreading due to this noise, the above-mentioned two-time matching method may be adopted, but since the left and right blocks must be scanned at least twice without coexistence, the reading rate decreases.

In view of the above problems, it is an object of the present invention to provide a barcode reading device that prevents misreading due to noise without reducing the reading rate.

[Means for Solving the Problems] In FIG. 1, a diagram showing the principle of the present invention, 1 is a scanning unit that repeatedly scans a barcode label 15 divided into left and right blocks by left and right guard bars and a center bar, and Convert reflected light into electrical signals.

Reference numeral 11 denotes a demodulating section, which demodulates the bar code for each left and right block based on the electric signal, and sets an identification flag 21 to the demodulated data 2o obtained by scanning from the left guard bar toward the center bar or from the right guard bar toward the center bar. and input it into the checking section 10.

Reference numeral 10 denotes a check section, which checks the demodulated data 20 of the left and right blocks.
When checking the normality of reading by combining the demodulated data 20 with the identification flag 21, the demodulated data 20 with the identification flag 21 is input at least twice, and when they match, the demodulated data 20 of the block is determined.

(Function) When the demodulating unit 11 starts demodulating by detecting the right or left guard bar LGB, RGB among a series of electrical signals inputted by repeatedly scanning the barcode label 15, the demodulating unit 11 starts the demodulation. An identification flag 21 is attached to the data 20 and the data is passed to the checking unit 10.

When the demodulated data 20 to which the identification flag 21 is attached is input, the checking unit 10 checks the demodulated data 2° as the demodulated data 20 of one block when it is input at least twice and they match. .

As a result, when scanning from the guard bar LGB or RGB to the center bar CB, it is necessary to scan twice, but when the other block is scanned from the center bar CB in the LGB or RGB direction, it only needs to be scanned once. .

As described above, since data is matched twice only in the scanning direction where noise is likely to be found, the reading rate is improved compared to the conventional method in which matches are made twice for both blocks, and misreading is prevented to the same extent. I can do it.

〔Example〕

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

FIG. 2 is a block diagram of one embodiment, FIG. 3 is a demodulation operation flowchart, and FIG. 4 is a check operation flowchart.

Reference numeral 1 denotes a scanning unit that repeatedly scans light and converts reflected light from the barcode label 15 into an electrical signal.

2 is an AD conversion circuit that binarizes the converted electrical signal.

Reference numeral 11 denotes a demodulator, which, when performing demodulation, first detects LGB or RGB, adds an identification flag 21 to the demodulated data 20, and stores it in the memory 9 together with other demodulated data 20.

A series of demodulated data 20 is stored in a memory 9 and passed to a checking section 10.

A checker section 10 verifies the normality of reading using check digits and the like. If demodulated data 20 with identification flag 2I is input, it is not input twice, and if it is input twice but does not match, read O
Wait for input without entering K.

Further, in the demodulation section 11, 3 is a bar width detection circuit that detects the black and white bar width of the binarized signal and encodes it.

4 is a filter circuit, left and right guard bars LGB, RG
B and center bar CB, and instructs the demodulation circuit 5 to start/stop demodulation, and if LGB or RGB is input following white data of a predetermined width (corresponding to the margin), the predetermined focus of the buffer 7 is detected. Set “1” to (
identification flag 21).

A demodulation circuit 5 converts the input bar width code into a numerical code while referring to a conversion table 6, and sets the 0/E-specific numerical code in a buffer 7.

Reference numeral 7 denotes a buffer, the contents of which are transferred to the memory 9 by a write circuit 8 every time one digit is demodulated.

In this example, the demodulated data 20 for each block is composed of 4 bytes when the block is composed of 4 digits, and in addition to the numerical code for each 1 digit, the 1 identification flag 21 for each 0/E is included. Granted.

In the above configuration, demodulation and check operations are performed as follows.

(1) The filter circuit 4 checks the data output from the bar width detection circuit 3, and if it detects <LGB, B in R, and CB following white data with a predetermined width or more,
Instructs the demodulation circuit 5 to start demodulation.

At this time, if it is LGB or RGB, the identification flag 21 of the buffer 7 is turned on.

(2) The demodulation circuit 5 demodulates the first digit and sets the 0/E and numerical data to the buffer 7.

(3) When the demodulation of one digit is completed, the write circuit 8 transfers the contents of the buffer 7 to the memory 9.

The above demodulation operation is completed at half block, that is, CB or LG.
This process is repeated until B (RGB) is detected.

In this way, the demodulation operation is performed while the barcode label 15 is being scanned, and the demodulated data 20 is sequentially transferred to the memory 9.
is stored in

(4) The check unit IO starts a check process during the demodulation operation, searches the memory 9, and if there is demodulated data 20 with the identification flag 21 on, searches to see if there are two or more sets, and if not, waits for input. .

Then, when there are two sets, the demodulated data 20 are compared,
If they do not match, it waits for input, and if they match, it is combined with the demodulated data 20 of the other block to check for normality, and if it is normal, it outputs normally.

As described above, since the two-time matching method is performed only when scanning from the guard bars LGB and RGB to the center bar CB, it is possible to prevent misreading due to bit shifts caused by noise without reducing the reading rate. .

〔Effect of the invention〕

As explained above, in the present invention, when scanning is performed from the right or left guard bar toward the center bar, the block is scanned twice, and when the demodulated data match, the reading of that block is OK. This has the effect of preventing misreading due to noise caused by the margin portion without reducing the reading rate.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the present invention, Fig. 2 is a configuration diagram of an embodiment,
Fig. 3 is a demodulation operation flowchart, Fig. 4 is a check operation flowchart, Fig. 5 is an explanatory diagram of the prior art, and Fig. 6
The figure is a diagram showing an example of bit shift due to noise. In the figure, 1 is a scanning section, 2 is an AD conversion circuit, 3 is a bar width detection circuit, 4 is a filter circuit, 5 is a demodulation circuit, 6 is a conversion table, 7 is a buffer, 8 is a write circuit, 9 is a memory, 1
0 is a check section, 11 is a demodulation section, 15 is a bar code label, 20 is demodulated data, and 21 is an identification check operation flowchart in FIG. , blasphemy ,. Maan (white) Conventional technology explanatory diagram Figure 5 GB B (1) Normal binary data (n) Bit knotted due to noise A diagram representing an example of bit shift due to binary data noise 6r71

Claims (1)

[Claims] a scanning unit (1) that repeatedly scans a barcode label (15) divided into left and right blocks by left and right guard bars and a center bar, and converts reflected light into an electrical signal;
It has a demodulation section (11) that demodulates the barcode for each left and right block based on the electric signal, and a check section (10) that combines the demodulated data of the left and right blocks and checks the normality of reading. The demodulation unit (11) adds an identification flag (21) to the demodulated data (20) obtained by scanning from the left guard bar toward the center bar or from the right guard bar toward the center bar, and inputs the same to the checking unit (10);
The checking unit (10) is characterized in that the demodulated data with the identification flag (21) is input at least twice, and when they match, it is checked as the demodulated data (20) of the block. .