JP2009230283A - Bar code scanner and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bar code scanner surely preventing double reading of a bar code even when an unauthorized interrupt occurs in a CPU (Central Processing Unit) by noise such as static electricity, and to provide a method for controlling the bar code scanner. <P>SOLUTION: A photosensor receives reflected light from the bar code, binarizing an electric signal to be output, and thereafter converts it into width information of bars and spaces constituting the bar code. Next, the width information is stored in a memory, and an interrupt signal generation part outputs an interrupt signal according to that the width information of all the bars and spaces constituting the bar code is completely stored. When the CPU receives the interrupt signal, the CPU sequentially reads the width information of the bars and the spaces from the memory, and erases the width information from the memory. After reading all pieces of the width information, the CPU decodes the width information into bar code information. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a barcode scanner used for reading a barcode and a control method thereof.

  Conventionally, a bar code formed by combining a plurality of types of bars and spaces is used for managing articles in the distribution industry. The bar code is read by a dedicated bar code scanner, and bar code information is input to the host device for information processing. In general, a bar code scanner recognizes reflected light obtained by irradiating a bar code with infrared rays or the like by a photo sensor, generates binarized data about bars and spaces, and stores this data therein. After being converted into bar and space width information by a decoding FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), it is decoded into bar code information that can be recognized by a host device.

  When a barcode is read by a barcode scanner, if the barcode is held over an infrared ray emitted from the barcode scanner for a long time, double reading may be performed in which the barcode once recognized by the scanner is read again. For example, in a retail store or the like, a barcode attached to a product is read by a barcode scanner, and the product data of the product is input to the product sales processing device for sale processing. Inconveniences such as double charges for the same product occur.

In order to deal with the problem of double reading, for example, a double reading prevention device for a barcode decoder described in Patent Document 1 has been proposed. This double reading prevention device stores the data read from the bar code in the data buffer, judges the coincidence / non-coincidence with the newly read data, and when the number of scans does not match or sets a preset reference number When it exceeds, it is configured to output newly read data.
JP-A-4-297969

  By the way, in the decoder FPGA or ASIC, the width information obtained from the binarized data is sequentially stored in the memory, and the width information has been obtained from all the bars and spaces constituting one barcode. A predetermined interrupt signal is issued to a CPU (Central Processing Unit). The CPU that detects this interrupt signal acquires the width information from the memory and decodes it into bar code information that can be recognized by the host device.

  However, the CPU obtains the width information from the memory not by the interrupt signal but also by an illegal interrupt such as noise generated when static electricity is generated near the circuit pattern on the board. When such erroneous CPU reading occurs, double reading occurs in order to read again the width information that has already been read from the memory. Further, the double reading prevention function described in Patent Document 1 cannot cope with double reading due to an illegal interrupt to the CPU.

  The present invention has been made based on the above situation, and its purpose is to reliably prevent double reading of a barcode even when an illegal interrupt occurs in the CPU due to noise such as static electricity. It is to provide a barcode scanner and a control method thereof.

  The bar code scanner according to the present invention includes a light receiving unit that converts reflected light from a received bar code into an electric signal and outputs the electric signal, and the electric signal output from the light receiving unit is applied to a bar and a space constituting the bar code. Binarization means for binarizing into corresponding signals, and width information conversion means for converting the electric signals binarized by the binarization means into width information of each bar and space constituting the barcode and outputting the information And storage means for storing the width information output by the width information converting means, and interrupting in response to completion of storing the width information of all bars and spaces constituting the barcode in the storage means. An interrupt means for outputting a signal; a read control means for reading the width information from the storage means when the interrupt signal output by the interrupt means is received; and the read control means And erasing control means for erasing the width information from said storage means and is characterized by comprising a decoding means for decoding the width information said reading control means has read the bar code information.

  According to the present invention in which such a measure is taken, a barcode scanner capable of reliably preventing double reading of a barcode even when an illegal interruption occurs in the CPU due to noise such as static electricity, and a control method therefor are provided. can do.

Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a main configuration of a barcode scanner 1 according to the present invention. The bar code scanner 1 includes a CPU 2 that is a control main body, firmware 3 that includes a control program necessary for the operation of the bar code scanner 1, a photo sensor 4 that detects the brightness of light and outputs an analog electric signal, and digitally converts the analog signal. An A / D conversion circuit 5 for converting signals, an FPGA 6 programmed to execute predetermined processing, and a USB (registered trademark) port 7 used for connection to an external device 8 such as a POS (Point Of Sales) terminal are provided. ing.

  The photosensor 4 receives reflected light when a laser beam emitted from a light source (not shown) scans a barcode to be read, and is reflected light caused by a color difference between bars and spaces constituting the barcode. An analog electric signal corresponding to the brightness of the signal is output to the A / D conversion circuit 5 (light receiving means). The A / D conversion circuit 5 binarizes the input electrical signal into data composed of “0” corresponding to the bar portion of the barcode and “1” corresponding to the space portion, and outputs the data to the FPGA 6 (binary). Means). The FPGA 6 generates 16-bit width information of each bar and space constituting the barcode from the input binary data, and outputs an interrupt signal to the CPU 2 at a predetermined timing. When the CPU 2 receives this interrupt signal, it acquires the width information from the FPGA 6 and proceeds with the decoding process according to the barcode standard. The barcode information decoded in this way is output to the external device 8 connected via the USB port 7.

  FIG. 2 is a block diagram showing a main configuration of the FPGA 6. The FPGA 6 includes a video signal input unit 10 that receives binary data input, a barcode detection unit 11 that detects barcode reading, a memory A and a memory B that store the width information, and a width to these memories A and B. A memory control unit 12 that controls writing and reading of information, a register 13 that stores predetermined information, and an interrupt signal generation unit 14 that generates an interrupt signal are provided.

  When the video signal input unit 10 detects an edge between “0” and “1” of the binary data, the video signal input unit 10 measures the time until the next edge is detected, and measures the measured data Together with the type of “0” or “1”, the measured time is output to the barcode detection unit 11 as 16-bit information. That is, the video signal input unit 10 is width information conversion means for converting the electrical signal binarized by the A / D conversion circuit 5 into width information of each bar and space constituting the barcode and outputting the information. The barcode detection unit 11 determines whether or not the input 16-bit information is barcode bar or space width information. If it is determined that the input is 16-bit information, the barcode control unit 11 sends the 16-bit information to the memory control unit 12. This is output together with the type of “0” or “1”, that is, the type of bar or space, and this 16-bit information is discarded when it is determined not to be width information. Receiving the output of the width information, the memory control unit 12 writes the width information into either the memory A or the memory B, and reads the width information when a request from the CPU 2 is received later.

  FIG. 3 is a schematic diagram showing a configuration of data stored in the memory A and the memory B. In the memory A and the memory B, a memory area capable of storing one width information for each address is formed. In this memory area, width information can be written and read out under the control of the memory control unit 12.

  Now, the memory control unit 12 can write the width information of another barcode input while reading the width information from either the memory A or the memory B into the other memory. FIG. 4 is a schematic diagram for explaining switching of memories used for reading and writing of width information. After writing the width information of a certain barcode into the memory A (ST101), the memory control unit 12 switches the memory B to the writing of the width information when the width information is read from the memory A. At this time, when the width information of another barcode is input from the barcode detection unit 11, the memory control unit 12 writes the width information in the memory B (ST102). After the width information is read from the memory A and the width information is written to the memory B, when the width information is read from the memory B, the memory A is switched to write the width information. At this time, when the width information of another barcode is input from the barcode detection unit 11, the memory control unit 12 writes the width information in the memory A (ST103). Thereafter, similarly, the memory A and the memory B are used for writing and reading the width information while switching appropriately. Thus, the processing of the memory control unit 12 that switches between the memory A and the memory B as appropriate constitutes a memory switching control means. Since the memory A and the memory B are configured to be switchable in this way, the width information of other barcodes input before the reading of the width information from the CPU 2 can be saved without being discarded. Reading efficiency is improved.

Next, taking the case where the width information is stored in the memory A as an example, the processing performed by the CPU 2 and the FPGA 6 will be specifically described with reference to the flowchart of FIG. When this processing is performed, a counter i and a counter N are formed in the register 13.
First, it is determined whether or not the 16-bit information input from the video signal input unit 10 in the barcode detection unit 11 is the width information of the bar or space constituting the barcode (ST201). This process is repeated until it is determined that the width information of the bar or space is determined (No in ST201), and when it is determined that the barcode is detected (Yes in ST201), the 16-bit information is displayed together with the type of the bar or space. The width information is input to the memory control unit 12. At this time, the memory control unit 12 initializes the counter i formed in the register 13 to “1” and stores the type of the bar or space of the width information (ST202).

  Next, the memory control unit 12 stores the width information at the address i of the memory A (ST203), and determines whether or not the input width information is interrupted, that is, whether or not the barcode is interrupted (ST204). . In this determination, for example, the elapsed time from when the width information is input by the timer is measured, and if the next width information is not input even after the predetermined time has elapsed, it is determined that the input width information has been interrupted. . When it is determined that the input width information is not interrupted (No in ST204), the counter i is incremented (ST205), and the processing returns to ST203 and the next received width information is the next address in the memory A. Write to i. As described above, the memory control unit 12 stores the input width information in the memory A in the order of addresses.

  On the other hand, when the memory control unit 12 detects that the input width information is interrupted (Yes in ST204), the interrupt signal generation unit 14 outputs an interrupt signal to the CPU 2 (ST206). In other words, the interrupt signal generation unit 14 is an interrupt unit that outputs an interrupt signal in response to the storage of the width information of all the bars and spaces constituting the barcode in the memory A.

  Thereafter, the CPU 2 acquires the value of the counter i stored in the register 13 and the type of the bar or space of the head width information stored in the processing of ST202 (ST207), and initially sets the counter N to “1”. (ST208). The value of counter i acquired at this time is stored and held in a memory area (not shown) of CPU 2 as the number Nmax of width information to be acquired by CPU 2.

  Next, the CPU 2 requests the FPGA 6 to read the width information. Upon receiving this request, the memory control unit 12 reads the width information stored in the address N of the memory A and outputs it to the CPU 2 (ST209), and writes “0” in the address N of the memory A (ST210). That is, the process of ST9 in which the CPU 2 requests the FPGA 6 to read the width information is a read control unit, and the process of ST10 in which the memory control unit 12 erases the width information read from the memory A is an erase control unit.

  Next, the CPU 2 acquires the value of the counter N from the register 13 and determines whether or not the value of the counter N has reached the number Nmax of width information to be acquired (ST211). When it is determined that the number Nmax of width information has not been reached (No in ST211), the counter N is incremented (ST212), and the memory control unit 12 is requested to read the width information again.

  On the other hand, when it is determined that the number Nmax of width information has been reached (Yes in ST11), the CPU 2 reads the bar or space of each width information read based on the type of the top bar or space acquired in the process of ST207. Is identified, and it is decoded into barcode information by collating with the barcode standard information held in advance (ST13). That is, the process of ST13 executed by the CPU 2 is a decoding unit. The decoded barcode information is output to the external device via the USB port 7, and the reading process is completed. Even when the width information is written to and read from the memory B, the processes of ST201 to ST213 are similarly executed.

  As described above, in the barcode scanner 1, when the CPU 2 acquires the barcode width information from the memory A or the memory B, the memory controller 12 stores the width information stored at a predetermined address in the memory A or the memory B. Is read and the width information is erased. For this reason, since the width information that has already been read is not read again from the memory A or the memory B, double reading of the barcode is surely prevented even when an illegal interruption due to noise such as static electricity occurs. be able to.

  In addition, this invention is not limited to the said embodiment as it is, In an implementation stage, in the range which does not deviate from the summary, each component can be deform | transformed and embodied suitably.

  For example, in the above embodiment, the barcode scanner 1 is configured using the FPGA 6, but the invention is not limited to this, and an ASIC designed to perform the same processing as the FPGA 6 may be used instead of the FPGA 6. .

  Further, when the CPU 2 acquires the barcode width information from the memory A, the memory control unit 12 reads the width information stored at a predetermined address of the memory A or the memory B and erases the width information. However, after reading the width information of all the bars and spaces constituting one barcode from the memory A or B, the width information stored in all addresses may be erased. Even in such a processing configuration, it is possible to prevent double reading when an illegal interrupt to the CPU 2 occurs.

  In addition to the memory A and the memory B, a larger number of memories may be mounted on the FPGA 6 and used for writing and reading width information as appropriate by the memory switching means. For example, in addition to the memory A and the memory B, the memory C is further mounted. When the width information stored in the memory A is read, the memory B is switched to write the width information. When the writing of the width information to the memory B is completed before completion, the memory C is switched for writing the width information. With such a configuration, the efficiency of reading a barcode can be further improved.

  In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from the overall components shown in the embodiment.

1 is a block diagram showing a main configuration of a barcode scanner according to an embodiment of the present invention. The block diagram which shows the principal part structure of FPGA in the same embodiment. The schematic diagram which shows the structure of the data memorize | stored in the memory in the embodiment. The schematic diagram for demonstrating switching of the memory in the embodiment. 4 is a flowchart of processing performed by a CPU and an FPGA in the embodiment.

Explanation of symbols

  A, B ... Memory, i, N ... Counter, 1 ... Barcode scanner, 2 ... CPU, 3 ... Firmware, 4 ... Photo sensor, 5 ... A / D conversion circuit, 6 ... FPGA, 7 ... USB port, 8 ... External device, 10 ... video signal input unit, 11 ... barcode detection unit, 12 ... memory control unit, 13 ... register, 14 ... interrupt signal generation unit

Claims (5)

A light receiving means for converting the reflected light from the received bar code into an electrical signal and outputting it,
Binarizing means for binarizing the electrical signal output by the light receiving means into signals corresponding to the bars and spaces constituting the barcode;
Width information conversion means for converting the electric signal binarized by the binarization means into width information of each bar and space constituting the barcode and outputting the information;
Storage means for storing the width information output by the width information conversion means;
Interrupt means for outputting an interrupt signal in response to the storage of the width information of all the bars and spaces constituting the barcode in the storage means;
Read control means for reading the width information from the storage means when receiving the interrupt signal output by the interrupt means;
Erasure control means for erasing the width information read by the read control means from the storage means;
Decoding means for decoding the width information read by the read control means into barcode information;
A bar code scanner comprising:   2. The bar according to claim 1, wherein the erase control unit erases the width information from the storage unit each time the read control unit reads the width information of one bar or space from the storage unit. Code scanner. The width information conversion unit, the storage unit, and the interrupt unit are implemented by an FPGA.
The read control means requests the FPGA to read the width information when the interrupt signal is received, and causes the width information to be read from the storage means, and the erase control means stores the width information. The barcode scanner according to claim 1, wherein the barcode scanner is erased from the means. A plurality of storage means;
When the read control means reads the width information from the specific storage means, the storage means for storing the width information output by the width information conversion means is changed from the specific storage means to the other storage means. 2. The barcode scanner according to claim 1, further comprising a memory switching control means for switching between the two. A light receiving step for converting the reflected light from the received bar code into an electrical signal and outputting it;
A binarization step for binarizing the output electric signal into a signal corresponding to a bar and a space constituting the barcode;
A width information conversion step of converting the binarized electrical signal into width information of each bar and space constituting the barcode and outputting the information;
A storage step of storing the output width information in a predetermined storage means;
An interrupt step of outputting an interrupt signal in response to the width information of all the bars and spaces constituting the bar code being stored in the storage means;
A reading step of reading the width information from the storage means when the control means receives the output interrupt signal;
An erasing step of erasing the read width information from the storage means;
A decoding step of decoding the width information read in the reading step into bar code information;
A control method for a bar code scanner, comprising:

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