JPS6120911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical reading systems, particularly barcode reading systems.

Barcode reading devices are broadly classified into those whose light beam scanning units, so-called scanners, are stationary types and those which are handheld.

Among these, hand-held scanners are designed to hold the scanner in your hand, bring it close to a barcode symbol affixed or printed on a product, and then operate a switch on the scanner to start reading. It's normal. However, with this method, there is a loss in the time from when the scanner approaches the barcode symbol to when it starts scanning.
Since a switch operation is required for each barcode symbol, when a large number of products are handled, such as in a supermarket store, this causes a great deal of fatigue to the operator.

In view of these drawbacks, the present invention seeks to provide a barcode reading method that automatically scans and reads barcode symbols when a scanner approaches a position where barcodes can be read. be.

According to the present invention, it is possible to obtain a barcode reading system in which a scanning light beam is continuously waved in a scanner, but a barcode decoding operation is performed only when a signal scanning a barcode symbol is sent.

Examples of the present invention will be described below.

FIG. 1 shows a block diagram of an embodiment of the present invention.

This device includes a photoelectric converter 1 that converts scanning reflected light into an electrical signal, a comparator 2 for noise signal cancellation and waveform shaping, and a device that determines whether or not this output signal is a signal obtained by scanning a barcode symbol. A barcode discrimination circuit 3, a barcode decoder 4,
It consists of a hand-held scanner 5 and a control circuit 6 for the scanner 5.

Simply put, the barcode discrimination circuit 3 photoelectrically converts scanning reflected light obtained by scanning a barcode symbol to obtain a pulse train-shaped electrical signal (hereinafter referred to as a barcode signal). Due to the nature of barcodes, if the scanning speed of the code signal is constant, the maximum value of the pulse interval is also determined, so it is detected whether or not the pulse train arriving from comparator 2 is continuous at an interval within this maximum value. This controls the decoding operation of the decoder 4. The configuration for this purpose includes a pulse generator 31 using a retriggerable monostable multivibrator, a clock pulse generator 32, an AND circuit 33, a counter 34, a flip-flop 35, and a counter reset circuit 36.

The pulse generator 31 uses the pulse from the comparator 2 as a trigger input and outputs a high level signal for a certain period of time t _1. If a trigger input is received again while the output is at a high level, the pulse generator 31 outputs a high level signal for a period of time t ₁ from this point onwards. Output. Therefore, if this time _t1 is set to be slightly larger than the maximum value of the pulse interval of the barcode signal, the pulse generator 31 will wait until the output generated by the first pulse of the barcode signal changes to low level. It is triggered again by the next pulse of the barcode signal, and is triggered in this manner sequentially, so that the output of the pulse generator 31 remains at a high level while the barcode signal is arriving.

On the other hand, when scanning characters or numbers other than the barcode symbol attached to an item, the spacing between these lines is usually larger than the maximum bar spacing of the barcode symbol and is irregular. The pulse interval of the electrical signal obtained from the comparator 2 is considerably larger than the maximum value of the pulse interval of the barcode signal. Therefore, when such a signal arrives, the pulse generator 31 is normally only triggered by the first pulse, and before the next pulse is input, the output changes to low level, and the output changes to high level. The state rarely exceeds time t ₁ .

From this, it is possible to determine whether the scanned signal is a barcode signal or not based on whether the high level output duration of the pulse generator 31 is sufficiently longer than the time _t1 .

The control circuit 6 includes an oscillator 6 that outputs a signal that defines the scanning period and angle of the light beam in the scanner 5.
1 and an analog switch 62 for switching the scanning angle.
The rotary reflector of the scanner 5 is rotated back and forth to swing the light beam (laser beam), but normally the light beam is swung repeatedly at a small angle, and then the analog switch 62 is sent from the flip-flop 35. The light beam is repeatedly swung at an angle that allows scanning the entire bar code only when a high-level signal arrives at the bar code.

Further, the barcode decoder 4 decodes the pulse signal, that is, the barcode signal, arriving from the comparator 2 using the high level signal from the flip-flop 35, and after the decoding is completed, the barcode decoder 4
Reset 5.

Next, the operation will be explained with reference to FIG. 2, which is a time chart of input and output signals of each part.

After the power is turned on and while the scanner 5 is brought close to the article on which the barcode symbol is affixed or printed, the scanning angle by the scanner 5 is small and there is no scanning reflected light to the photoelectric converter 1, so the scanning angle to the pulse generator 31 is small. No trigger input, flip-flop 35
The output also remains at low level. However, when a barcode symbol is scanned, the reflected light is converted into a pulse signal by the photoelectric converter 1 (Fig. 2 A), and then waveform-shaped into a rectangular pulse signal by the comparator 2 (Fig. 2 B). be done.

In the barcode discrimination circuit 3, the pulse generator 31
is triggered by the first pulse of pulse signal RO and outputs a high level signal (FIG. 2 C), and the pulse interval of signal RO is equal to the output duration time t ₁ of pulse generator 31.
Since it is shorter, the output of the pulse generator 31 continues to be at a high level because it is repeatedly triggered every time a pulse arrives.

The counter 34 receives a pulse (second pulse) from the clock pulse generator 32 which is input through the AND circuit 33.
After counting the predetermined number, a signal (second
Figure E) is output. This clock pulse number n ₄ is
The number of clock pulses is set to be sufficiently larger than the number of clock pulses corresponding to the output duration time _t1 of the pulse generator 31, so that the arrival of the barcode signal from the comparator 2 is detected at the output level of the counter 34. be able to. When the output of the flip-flop 35 (FIG. 2) becomes high level, the analog switch 62 in the control circuit 6 changes the output frequency of the oscillator 61 and changes the scanning angle of the scanner 5 so that all bar codes can be scanned. At the same time, the barcode decoder 4 starts decoding the pulse signal coming from the comparator 2 and digitally displays the information represented by the barcode.

In this way, the decoding operation in the barcode decoder 4 is defined by the output of the flip-flop 35, and when the decoding operation starts, the start and end of the barcode signal are determined from the signal arriving from the comparator 2, and the barcode signal portion is determined. It is now possible to decipher only the Therefore, the barcode decoder 4 does not start the decoding operation unless the signal coming from the comparator 2 is a barcode signal.
Even if a portion other than the barcode symbol is scanned, a signal similar to the barcode signal may be obtained and the output of the pulse generator 31 may continue. However, since such a signal does not have regularity like a barcode signal, the barcode decoder 4 cannot decode it, and in this case, the flip-flop 35 is automatically reset, so the scanner 5 All you have to do is bring it close to the barcode symbol and scan it.

When the flip-flop 35 is reset after the decoding is completed, the analog switch 62 is switched to reduce the scanning angle by the scanner 5, and scanning for barcode discrimination is performed again. After the decoding is completed, the next decoding is not started unless the pulse signal from the comparator 2 is interrupted for a certain period of time, thereby preventing repeated reading of the same bar code signal. The counter reset circuit 36 resets the counter 34 when the pulse signal from the comparator 2 is interrupted and the output of the pulse generator 31 becomes low level. In other words, preparations for decoding the next barcode are made until the scanner 5 approaches the barcode symbol of the next article after the decoding of the barcode of a certain article is completed.

As is clear from the above explanation, in the present invention, since scanning by the scanner is constantly repeated, a barcode signal can be obtained by bringing the scanner closer to a barcode symbol, and whether or not the incoming signal is a barcode signal can be obtained. The barcode decoder automatically decodes the barcode signal for which the next scan can be obtained only when it is a barcode signal, and does not decode it in other cases. There is no need to operate a switch to start and stop scanning for each code symbol, making it very easy to handle and greatly improving work efficiency.

Furthermore, since the scanning angle for barcode discrimination is made smaller than normal scanning angles, the load on the scanning mechanism of the scanner is reduced and power consumption, temperature rise, etc. can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention.
Figure 2 is a time chart of the input and output waveforms of each part. In the figure, 1 is a photoelectric converter, 2 is a comparator, and 3
is a barcode discrimination circuit, 4 is a barcode decoder,
5 is a scanner, 6 is a control circuit, 31 is a pulse generator, 32 is a clock pulse generator, 33 is an AND circuit, 34 is a counter, 35 is a flip-flop, 36 is a counter reset circuit, 61 is an oscillator, 62 is an analog switch, 63 is an amplifier.

Claims (1)

[Claims] 1 In a device that scans a barcode with a light beam using a handheld scanner, converts the scanned reflected light into an electrical signal, and reads the information represented by the barcode using a decoder, the electrical signal is in a pulse form and Furthermore, it is possible to determine whether the electrical signal is a barcode signal obtained by scanning a barcode by detecting whether or not the pulse interval continues for a predetermined period of time within a predetermined period of time. and a control circuit for switching at least the scanning angle of the scanner according to the determination result of the determining means, and when the bar code signal is detected while the light beam is continuously swung. . An optical reading system characterized in that the scanning angle is increased and the operation of the decoder is started.