JPH02235188A - Bar code reader - Google Patents

Abstract

PURPOSE:To discriminate respective bar codes and to eliminate the need for rapid decoding by storing the scanning position and scanning time of a laser beam and bar code data as the data of one group, then reading out and decoding the data. CONSTITUTION:A binary signal is outputted from a binary signal (binarization circuit) 12 based on reflected beams from each of bar codes 30 to 32. At the timing of the output, the scanning positions of the laser beams are detected by a counter 13 and the time is detected by a counter 14. The binary signal, the scanning positions and the time information as the data of one group are successively stored in a memory 17 so as to store plural groups of data. Then, the data are read out from the memory 17 in each group and decoded by a decoder 18 to read out the information of the bar code and to detect the passing position and passing time of the bar code. Thereby, rapid decoding processing can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a barcode reading device that optically reads barcodes attached to moving objects. [Prior Art] A method of attaching a barcode to an object and optically reading it is widely used for object identification, product management, and the like. As a reading device for reading barcodes, methods such as a CCO method and a laser scan method are adopted.

However, there are cases where it is necessary to read each bar code attached to a plurality of objects moving over a wide range, and also to detect the passing position and time of each bar code. In such a case, conventionally, the reading line is first divided so that a plurality of barcodes do not pass through at the same time, and one reading device is placed in each divided range.

Then, each reader reads the barcode as it moves within the corresponding range, estimates the passing position of the barcode from the placement position of the reader, and measures the time when the reading result is obtained using an external timer. to estimate the barcode passage time.

[Problem to be solved by the invention]

Therefore, the conventional method as described above has a problem in that it is not possible to accurately detect the passing position and passing time of the barcode.

Additionally, if multiple barcodes exist on the reading line handled by one reading device, in order to be able to read these barcodes, a decoding device capable of extremely high-speed processing must be installed. The problem is that it needs to be kept.

These problems limit the expansion of barcode applications. The present invention has been made in view of the above circumstances, and includes a built-in means for detecting the scanning position and scanning time of a laser beam, and combines the information from this means and the barcode reading signal into one set of data. Once such data is stored in memory, it is retrieved one set at a time from memory and decoded. Even when multiple bar codes pass simultaneously on the reading line, each bar code can be identified. It is an object of the present invention to provide a barcode reading device that can read barcodes and accurately detect the passing position and passing time of each barcode.

[Means to solve the problem]

A barcode reading device according to a first aspect of the present invention scans and irradiates a moving barcode with a laser beam, receives a reflected beam from the barcode, and reads the barcode based on the reflected beam. In the barcode reading device, a light receiving element receives the reflected beam, a binarization means binarizes a light reception signal of the light receiving element, and scanning of the laser beam when the light receiving element receives the reflected beam. a scanning position detection means for detecting a position; a time detection means for detecting a time when the light receiving element receives the reflected beam; a binary signal from the binarization means in one scan; a memory for storing a plurality of sets of data including scanning position information from the scanning position detection means and time information from the time detection means;
The present invention is characterized by comprising means for extracting data one set at a time from the memory, reading the barcode, and detecting the passing position and passing time of the barcode.

Moreover, the barcode reading device of the second invention according to the present invention includes:
The reading device of the first invention is characterized in that it further includes means for preventing reading the same barcode more than a predetermined number of times.

(Function) In the reading device of the present invention, a binary signal indicating percode information is obtained in the binary circuit based on the reflected beam from the barcode. At the obtained timing, the scanning position detector detects the scanning position of the laser beam, and the time detector detects the time.Then, this binary signal and the scanning position and time information are set as a set of data. Multiple sets of such data are stored one after another in the memory.Finally, data sets are taken out from the memory one by one and decoded to read the barcode information and detect the barcode passing position and passing time.The present invention In this case, the obtained information is temporarily stored in the memory and decoded when there is time.Therefore, high-speed decoding is not required.

Further, the second aspect of the present invention includes means for controlling so that the same barcode is not read more than a predetermined number of times. Therefore, one barcode is read less than a predetermined number of times. In this case, the number of data sets that can be obtained is limited, so there is no risk of memory overflow.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 is a schematic diagram showing the configuration of a reading device according to the present invention. In the figure, 30, 31, 32 are bar codes to be read, and each bar code 30, 31, 32 is attached to an object (not shown). It moves along with the object in the front and back directions of the drawing.

Further, 2 in the figure is a laser diode (LD) that emits a laser beam that is high-frequency modulated by the modulation circuit 1,
A lens system 3, a mirror 4.5, and a polygon mirror 6 are optically coupled to the laser diode 2 in this order, and the laser beam emitted from the laser diode 2 is
The light passes through the lens system 3, is reflected by the mirror 4.5, and enters the polygon mirror 6. The laser beam 34 reflected by the polygon mirror 6 is irradiated onto the barcode 30, 31, 32 while scanning the reading line 33 in the direction of the arrow in accordance with the rotation of the polygon mirror 6. The reflected beam 35 from the barcodes 30, 31, 32 for the laser beam 34 is reflected by the polygon mirror 6 and the mirror 5, passes near the mirror 4, is focused by the light receiving lens 8, and is sent to the disturbance light removal filter. After passing through 9, the light is incident on the light receiving element 10. Further, a sensor 7 is provided near the polygon mirror 6 to receive the reflected beam 36 from the polygon mirror 6 when the polygon mirror 6 is at a specific angle. When light is received, the timing signal is output to a scanning position counter 13, which will be described later. Note that FIG. 1 only shows the optical path of the laser beam in the barcode 31, and the remaining barcodes 30.
The optical path for 32 is omitted.

The light receiving element 10 converts the amount of light received into an electrical signal and outputs it to the demodulator 11. The demodulator 11 demodulates this electrical signal into a barcode light reception signal corresponding to the barcode and outputs it to the binarization circuit 12. The binarization circuit 12 binarizes the barcode light reception signal, and converts the barcode light reception signal into a binarized signal (0.1 of the barcode).
) is output to the presence/absence detection circuit 15. The presence/absence detection circuit 15 detects whether or not the barcode has passed based on the binary signal from the binarization circuit 12. When it is confirmed that the barcode has actually passed, the presence/absence detection circuit 15 transmits the binary signal to the memory control circuit 1.
Output to 6.

Further, information on the scanning position of the laser beam is input from the scanning position counter 13 and time information is input to the memory control circuit 16 from the time counter 14.

After being reset in synchronization with the timing signal from the sensor 7, the scanning position counter 13 starts counting at a constant frequency. Therefore, the count value of the scanning position counter 13 always corresponds to the laser beam scanning position, and the scanning position counter 13 outputs this count value as scanning position information to the memory control circuit 16. Further, the time counter 14 counts at regular intervals after being reset at the reference time. Therefore, the count value of this time counter 14 always corresponds to the time, and the time counter 14 outputs this count value to the memory control circuit 16 as time information. When the binary signal is input, the memory control circuit 16 samples the count value of the scanning position counter 13 and the count value of the time counter 14 at this timing, and combines the binary signal and these count values into one set. Write to memory 7 as data. Note that the memo IJ17 can be a ring buffer memory or a first-in first-out memory.
You can use memory etc. In addition, 18 in the figure is the memory 1
The decoding device 18 reads one set of data from the memory 17 and decodes the data, and the decoding device 18 includes a reading section 19 that reads out one set of data from the memory 17, a direction determining section 20 that determines the direction of the barcode, and a decoding section 21 that reads barcode information and detects the passing position and passing time of the barcode.

Next, the operation will be explained.

A high-frequency modulated laser beam 34 from the laser diode 2 passes through a lens system 3, mirrors 4 and 5, and a polygon mirror 6, and is scanned on a reading line 33. The reflected beam 35 from the barcodes 30, 31, 32 located on the reading line 33 passes through the polygon mirror 6, the mirror 5, the light receiving lens 8, and the disturbance light removal filter 9, and then reaches the light receiving element 10.
The light is received and converted into an electrical signal. After this electric signal is demodulated by a demodulator 11, it is converted to 0 by a binarization processing circuit 12.
, 1 into a binary signal.

The disulfide signal representing barcode information is input to the memory control circuit 16 after being checked by the presence/absence detector 15 to see if it is actually a signal derived from the barcode. Further, in synchronization with the timing of this input, scanning position information and time information are inputted from the scanning position counter 13 and the time counter 14 to the memory control circuit 16. A set of data including these two types of information and the binary signal is stored in the memory 17. This storage operation in the memory 17 is performed every time the binary signal for the barcode is input to the memory control circuit 16, so the laser beam 3 is stored multiple times.
By scanning No. 4, a plurality of sets of data are stored in the memory 17. The data stored in the memory 17 is read out one set at a time by a decoding device 18, and the decoding device 18 reads barcode information and detects the passing position and passing time of the barcode. Note that when a plurality of reading devices are provided, the passing direction of the barcode can also be detected.

As described above, in the present invention, a binary signal indicating the information of each barcode and the scanning position information and time information obtained in synchronization with the detection of this binary signal are decoded as one set of data. Therefore, the barcode passing position and passing time can be accurately detected, and each piece of information can be obtained independently for each barcode.

Furthermore, in the present invention, since the detected data is temporarily stored in the memory, the decoding process can be performed when there is sufficient time, and the decoding device is not required to have high-speed processing capability. The timing at which the decoding process is performed is
Even if the barcode is scanned much later than the time when the barcode is scanned, the detected barcode passing position and time will not be inaccurate.

Furthermore, it is possible to increase the writing speed to memory sufficiently, so even if multiple barcodes exist simultaneously on a reading line, the data for each barcode is stored in memory as independent data. and each barcode can be independently identified.

By the way, if the scanning speed of the laser beam 34 is fast and the moving speed of the barcodes 30, 31, 32 is slow, the same barcode will be scanned many times. Therefore, an overflow may occur in the memory 17, or the processing of the decoding device 18 may not be able to keep up with the writing to the memory 17, which may result in a reading error. A device devised to prevent such a possibility is the second invention of the present invention. This second invention is such that the same barcode is not read more than a predetermined number of times.

FIG. 2 is a schematic diagram showing the configuration of this second invention, and the parts in the figure with the same numbers as in FIG. In the second invention, a number limiting device 22 is provided between the presence/absence detection circuit 15 and the memory control circuit 16 to limit the number of times one bar code is read. FIG. 3 is a schematic diagram showing the internal configuration of this number-of-times limiting device 22, which includes a mask signal generation circuit 221 that generates a mask signal in accordance with the binary signal that has passed through the presence/absence detection circuit 15. , a delay circuit 222 that delays the mask signal by a predetermined number of scans;
The gate circuit 223 does not allow the binary signal to pass when the delayed mask signal is present.

Next, we will discuss the operation of this number-of-times limiting device 22 in detail, taking as an example the case where the maximum number of readings for one barcode is 5 (the case where the same barcode is not read six times or more consecutively). Explain in detail.

FIG. 4 is a waveform diagram of various signals for explaining this operation, and the waveform diagram (al is a scan synchronization signal synchronized with the start timing of one scan. When the digitized signal is input to the mask signal generation circuit 221, the mask signal generation circuit 221 generates a mask signal (waveform diagram (
C)) is generated and output to the delay circuit 222. In the delay circuit 222, the input mask signal is delayed by a phase equal to the scanning time of the number of times (5 times) corresponding to the reading limit number of times (here, 5 times), and the delayed mask signal (waveform diagram (d) ) is output to the gate circuit 223. Note that the delay operation at this time is controlled by a clock signal from a reference oscillator (not shown). In the gate circuit 223, the binary signal that has passed through the presence/absence detection circuit 15 is masked by this delayed mask signal, and the binary signal after gate processing (waveform diagram (e)) is sent to the memory control circuit 16. Output to.

In this example, in the sixth scan, a binary signal A derived from the same barcode as that detected in the first scan is detected, but the gate processing in the gate circuit 223 The value signal A is turned off, and reading is not performed six times or more consecutively. Since the binary signal B derived from another barcode is not detected in the first scan, it is read without being subjected to gate processing in the sixth scan.

In this way, even if one barcode is present on the reading line many times in succession, it is actually read only the first predetermined number of times. Therefore, even when a plurality of barcodes move at an extremely low speed, the amount of data stored in the memory 17 is limited, which may cause the memory 17 to overflow or the processing speed of the decoding device 18 to slow down. There is no risk of not being able to keep up with the writing speed to the memory 16.

〔Effect of the invention〕

As detailed above, in the barcode reading device of the present invention, even when a plurality of barcodes pass simultaneously on the reading line, each barcode can be independently identified, and the information of each barcode can be read and , it is possible to accurately detect the passing position and passing time of each barcode. the result,
The present invention has excellent effects such as being able to greatly expand the range of use of barcodes.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a barcode reading device according to the present invention, FIG. 2 is a schematic diagram showing the configuration of a barcode reading device according to a second aspect of the present invention, and FIG. FIG. 4 is a schematic diagram showing the internal configuration of the number-of-times limiting device, and is a waveform diagram of various signals for explaining the operation of this number-of-times limiting device. 6... Polygon mirror 10... Light receiving element 12.
...Binarization circuit l3...Scanning position counter 14.
...Time counter l6...Memory control circuit 17.
...Memory 18...Decoding device 22...Number of times limiting device 30, 31.32...Barcode 33.
...Reading line 34...Laser beam 35...
Reflected beam patent applicant: Sumikin Control Engineering Co., Ltd.
given name)

Claims (1)

[Scope of Claims] 1. A barcode reading device that scans and irradiates a moving barcode with a laser beam, receives a reflected beam from the barcode, and reads the barcode based on the reflected beam, comprising: a light-receiving element that receives the reflected beam; a binarization means that binarizes the light-receiving signal of the light-receiving element; and a scanning position detector that detects the scanning position of the laser beam when the light-receiving element receives the reflected beam. means, a time detection means for detecting the time when the light receiving element receives the reflected beam; and a binary signal from the binarization means and a scanning signal from the scanning position detection means in one scan. A memory for storing a plurality of sets of data, including position information and time information from the time detection means; and a memory for extracting data one set at a time from the memory, reading a bar code, and determining the passing position of the bar code. and means for detecting passage time. 2. The barcode reading device according to claim 1, further comprising a control means for controlling not to read the same barcode more than a predetermined number of times.