JP2751641B2 - Barcode reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a POS (Point of Sal
e) Bar code readers used in terminals and the like.

[0002]

2. Description of the Related Art A stationary bar code reader emits a laser beam from a reading window, and an operator scans a bar code printed or affixed to a product to be moved on the reading window, and reflects the reflected light as an electric signal. Convert to and read the barcode. Generally, in a bar code reading device for a POS terminal, the movement of a product is manually performed by an operator. Because of this, the time to pass over the reading window is limited, and the speed of the scanning beam is high, so that the demodulation processing for restoring the read barcode content is performed by hardware, and this hardware uses the barcode. And is configured to read only one type of barcode.

In recent years, there has been a demand for stationary bar code readers to read various types of bar codes.
In addition to superstores that require conventional reading speeds, department stores that use barcodes different from barcodes used for food etc. are also required to have high reading speeds and hands-free, This is because stationary barcode readers have come to be used.

[0004]

For this reason, in order to read various types of bar codes and to demodulate the contents, it is sufficient to configure hardware for each type of bar codes. The size and cost increase. The present invention has been made in view of the above problems,
It is an object of the present invention to provide a barcode reading device in which only a barcode data group among data read by a barcode detection unit is extracted by hardware and demodulated by firmware.

[0005]

FIG. 1 is a diagram illustrating the principle of the present invention. In the figure, reference numeral 101 denotes a barcode detection unit that reads a barcode, and 102 denotes a plurality of storage units, which are a barcode detection unit.
101 stores the read data. 103 selects which storage unit 102 stores the data read by the storage control unit, detects barcode data from the read data, and detects the address of the barcode data stored in the storage unit 102. I do. Reference numeral 104 denotes an address storage unit that stores the address detected by the storage control unit 103. 105
Reads out the address from the address storage unit 104 in the bar code demodulation unit, reads out the bar code data from the storage unit 102 based on this address, and performs demodulation processing.

Further, the storage unit 102 is constituted by a ring buffer, and overwriting is performed until a bar code portion is detected.

A set of a barcode recognition circuit of the storage control unit 103 and an address storage unit 104 for storing an address when the barcode detected by the barcode recognition circuit is stored in the storage unit 102 is stored in the barcode. Provided for each type.

Further, a circuit for operating only a desired set of the set of the bar code recognition circuit and the address storage unit 104 is provided.

[0009]

According to the above configuration, the data read by the barcode detection unit 101 is stored in the storage unit 10 selected by the storage control unit 103.
2, barcode data is detected from the read data, and the address of the barcode data stored in the storage unit 102 is stored in the address storage unit 104. The barcode demodulation unit 105 reads an address from the address storage unit 104, reads barcode data from the storage unit 102 based on the address, and performs a demodulation process. The storage control unit 103 selects one storage unit 10 when selecting the storage unit 102.
2 stores the read data until the barcode data is stored.After storing the barcode data, the subsequent data is stored in the next storage unit 102, and when the barcode data is stored again, the subsequent data is stored in the next storage unit. And then similarly stored in another storage unit 102 one after another.

When the bar code data is stored in the first ring buffer by using the storage unit 102 as a ring buffer, the read data is stored in the second ring buffer. During this time, if the barcode demodulation unit 105 has read the barcode data from the first ring buffer that has already stored the barcode data, then the second ring buffer stores the barcode data, and then the first ring buffer stores the barcode data. The read data can be stored in the ring buffer. That is, bar code data can be stored alternately in the two ring buffers. When the barcode data is stored in the second ring buffer and the barcode demodulation unit 105 has not read the barcode data from the first ring buffer, the barcode data is stored in the third ring buffer. As described above, the storage capacity of the storage unit 102 can be reduced by normally storing read data in two ring buffers and in three ring buffers if two are insufficient.

Further, by providing a combination of a bar code recognition circuit and an address storage unit 104 for each type of bar code desired to be read, the bar code demodulation unit 105 can perform demodulation processing of these bar codes by firmware. Since the barcode demodulation unit 105 can be used in common, the circuit scale of the demodulation device does not increase.

The bar code recognition circuit and the address storage unit
By providing a circuit that effectively activates only the bar code type set to be read out of the pair with 104, the bar code type set that is not read out is activated and the data scanned obliquely with respect to the bar code. It is possible to prevent erroneous reading of erroneously recognizing a bar code that is not a reading target.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram of the stationary scanner according to the present embodiment. This device comprises an optical system and a control system. The optical system is composed of a laser unit 1 for generating a laser, a laser control circuit 2 for controlling the laser unit 1, and a laser beam reflected from the laser unit 1 by a polygon mirror. Optical unit 3 for scanning on code
A motor 4 for rotating the polygon mirror, a photodetector 5 for receiving the laser beam reflected on the bar code, an amplifier circuit 6 for amplifying the output of the photodetector 5, and an output of the amplifier circuit 6. To an analog / digital converter (A / D circuit) 7 for converting a bar code into a digital value, an LED lamp 8 indicating a reading result, and a signal for notifying an operator that the bar code has passed through the optical unit 3 and has been read. And a speaker 9 for generating sound.

The control system comprises a scanner control circuit 10 for controlling the optical system, a demodulation circuit 11 for demodulating digital data of the A / D circuit 7, and an I / F control unit 12 for interfacing with the POS terminal. Is done.

FIG. 3 is a block diagram showing the configuration of the control system. The CPU 13, the ROM 14, and the RAM 15 perform bar code demodulation, optical system interface control, POS interface control, and the like. The interface unit 16 is a driver
The POS terminal 18 is interfaced via the receiver 17. The optical system controller 19 also interfaces with the optical system 21 via the driver / receiver 20. The bar width counter 22 counts the bar width from the bar code signal received from the optical system 21 and obtains the bar width. The buffer control unit 23 stores the bar width count data counted by the bar width counter 22 in the bar width count data buffer 241 or 242, and stores a buffer when the start / stop detection circuit detects the start portion and the stop portion of the bar code. 241 and 24
Then, the address at which the barcode data is stored in the buffer 241 or 242 is stored in the pointer instruction buffer 25.

Bar width count data buffers 241, 242
Is a buffer for storing bar width count data, and the bar width count data written to this buffer 24 includes:
Not only the barcode portion but also data (hereinafter referred to as dust data) in which characters and the like printed around the barcode are black and white information are included. Therefore, if a lot of characters such as a description of a product are written around the barcode, garbage data increases, and the buffer 24 becomes full. Therefore, in this embodiment, a ring buffer is used as shown in FIG. If a ring buffer is used, the dust data portion is overwritten, and the bar code data portion is also demodulated by C demodulation.
After reading by the PU 13, overwriting can be performed, so that the storage capacity can be reduced. It suffices if there is a storage capacity for the maximum number of bars of the barcode as the minimum storage capacity. The pointer instruction buffer 25 stores the address of the bar code data stored in the bar width count data buffer 24.

Next, the operation of this embodiment will be described with reference to FIGS. FIG. 5 is an operation flowchart of the present embodiment. First, a bar code is scanned with a laser beam. FIG. 6 shows a situation in which laser beams A and B scan a product on which a barcode is printed, and the barcode and dust data around the barcode are converted into white / black signals and detected by this scanning. This is digitally converted (step 51), and the bar width of each of the white bar and the black bar is counted by the bar width counter 22 (step 52). The above processing is performed by hardware.

FIG. 7 shows a buffer 24 for bar width count data.
FIG. 2 is a diagram showing 1,242 and a storage area of a pointer instruction buffer 25. The operation of these buffers is performed as follows. Data (barcode data and dust data) is buffered from the beginning of the buffer 241. Buffer 241
If there is no bar code data before the end of
It returns to the beginning of 1 (the above is step 53). When the start / stop portion of the barcode is detected, the start address and the stop address are stored in the buffer 251 (step
54). Next, the data is buffered in the buffer 242.
The buffer 242 operates similarly to the buffer 241 (steps 55 and 56).

Here, the bar code data stored in the buffer 241 must be demodulated by the firmware in the buffer 242 before the next bar code data is detected. If it is not completed, another buffer 243 needs to be added. Assuming that the rotation speed of the rotation motor 4 of the polygon mirror is 6000 rpm, that is, 10 ms per rotation, the number of times the laser beam scans the bar code during this period is about 1 to 3 times. It is necessary to perform demodulation processing. Actually 2ms
It can be demodulated by the degree.

The bar code data read from the bar width count data buffer 24 is used to remove dust data by a software filter (step 57). In this embodiment, in order to reduce the hardware circuit scale, only the start part and the stop part and the number of elements between them (the number of white and black bars) are checked. Various checks defined in the code are performed, final filtering is performed, and all garbage data is deleted. As a result, the B beam data and dust data are discarded in FIG.
Only the data part of the beam is extracted. One of the checks is a check of the adjacent character length of the barcode by the firmware.

The bar code data thus extracted is demodulated by the firmware (step 58). Since the barcode data is input many times, steps 50 to 58 need to be repeated several times. If the data thus demodulated is different from the previously input data, if different data is demodulated, all the different data are buffered (step 59). Since the data demodulated in this manner may include misread data, various checks specified in the code (for example, checks using a modulus 10 check code) are performed, and only the barcode data that passes all the checks is displayed. It is determined that code reading is completed (step 60).

In this embodiment, one type of bar code is read. However, the number of pairs of the start / stop detection circuit of the buffer control unit 23 and the pointer instruction buffer 25 is equal to the number of bar code types. Accordingly, it is possible to read these types of barcodes. Further, by providing a circuit that effectively operates only the set of the bar code type desired to be read out of these sets, occurrence of erroneous reading can be prevented. This is because, when a set of barcode types not to be read is also operating, when the barcode is scanned obliquely, the barcode may be in the same state as the barcode not to be read, resulting in erroneous reading.

[0023]

As is apparent from the above description, according to the present invention, only bar code data is extracted from detected data and demodulated by firmware, so that hardware for demodulating each bar code type is used. Do not need. For this reason, the circuit scale is reduced, and the demodulation logic can be easily changed because the demodulation unit is configured by firmware. Further, by using a ring buffer as the buffer for storing the read data, the capacity can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of a stationary scanner according to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of the present exemplary embodiment.

FIG. 4 is a diagram showing a configuration of a ring buffer.

FIG. 5 is an operation flowchart of the present embodiment.

FIG. 6 is a diagram illustrating scanning of a barcode by a laser beam.

FIG. 7 is a diagram illustrating a storage area of a buffer for storing detected data.

[Explanation of symbols]

 13 CPU 14 ROM 15 RAM 19 Optical system control unit 20 Driver / receiver 21 Optical system 22 Bar width counter 23 Buffer control unit 24 Bar width count data buffer 25 Pointer instruction buffer

Claims (4)

(57) [Claims] 1. A bar code detector (101) for reading a bar code, a plurality of storages (102) for storing data read by the bar code detector (101), and the bar code detector (101). The storage control for selecting the storage section (102) for storing the read data, recognizing a bar code data group from the read data, and detecting an address at which the bar code data is stored in the storage section (102). Unit (103) and an address storage unit (104) for storing an address detected by the storage control unit (103).
And a bar code demodulation unit (105) for reading bar code data from the storage unit (102) based on the address of the address storage unit (104) and performing demodulation processing. . 2. The bar code reading device according to claim 1, wherein said storage unit (102) is constituted by a ring buffer. 3. A bar code recognition circuit of the storage control unit (103) and an address storage unit (104) for storing an address of the bar code detected by the bar code recognition circuit to be stored in the storage unit (102). 2. The bar code reader according to claim 1, wherein a set is provided for each bar code type. 4. The bar code reading device according to claim 3, further comprising a circuit for operating only a desired set of the set of the bar code recognition circuit and the address storage unit (104).