KR940007936B1 - Light intensity automatic control apparatus of barcode scanner - Google Patents

Abstract

The apparatus comprises a clock generator for generating a clock pulse, a digital-to-analog converter for converting a prescribed number of bits among bits generated from the clock generator to a sawtooth analog signal, and a light generator for varying the light quanity to be scanned to a bar code, thereby accurately sensing the bar code.

Description

Light quantity automatic control device of barcode scanner

1 is a schematic diagram of a typical barcode scanner system.

2 is a configuration diagram of an embodiment of the automatic adjustment of the amount of light of a barcode scanner according to the present invention.

3 is a detailed block diagram of the clock generator of FIG.

4 to 6 are explanatory diagrams showing an example of output of a digital / analog converter when an arbitrary bit is selected in the clock generator.

* Explanation of symbols for main parts of the drawings

1: Clock generator 2: Light generator

3: barcode 4: lens

5 imaging device 6 small signal amplifier

7: comparison unit 8: microcomputer

9: memory section 11: digital / analog conversion section

The present invention relates to a barcode scanner for barcode recognition, and more particularly, to automatically adjust the brightness of a light source when scanning a barcode so that an image pickup device analyzes the barcode at the most appropriate light source brightness. It relates to a control device.

As shown in FIG. 1, a typical barcode scanner is reflected by a light generating unit 2 for generating an optical signal and scanning the barcode 3 with a black bar and a white bar of the barcode 3. According to the lens 4 for condensing the incident optical signal, the clock generator 1 generating a clock pulse of a predetermined period by counting a frequency to an arbitrary bit, and according to the clock pulse generated by the clock generator 1 An image pickup device 5 for capturing an optical signal through the lens 4 and converting the signal into an electrical signal; and a small signal amplification for amplifying and outputting an electrical signal corresponding to the optical signal output from the image pickup device 5 to a predetermined level. The comparison unit 7 compares the signal hole reference signal amplified by the small signal amplifier 6 with the comparison unit 7 and outputs the result as a digital signal, and the digital signal output from the comparison unit 7. To store the data in the memory unit 9 and store the stored data. A synchronism with the clock pulses of the clock generator (1) consists of a microcomputer 8 for controlling the overall operation of the system as well as a bar code scanner and also sent to the host computer 10.

The bar code 3 is composed of a start bar indicating the start, a middle bar and an end bar indicating the end, and between the start bar and the end bar, pure bar code data exists.

In the conventional barcode scanner configured as described above, when the optical signal scanned by the light generator 2 is incident on the barcode 3 and reflected, the lens 4 condenses the optical signal reflected by the barcode 3 to capture the image pickup device 5. ).

In this case, the amount of light incident on the image pickup device 5 is different from the amount reflected by the white bar and the black bar of the barcode 3.

Therefore, the imaging device 5 converts the optical signal incident through the lens 4 into an electrical signal corresponding to the clock pulse of the clock generator 1 in synchronization.

The signal output from the image pickup device 5 is amplified by the small signal amplifier 6 and input to the comparator 7, and the comparator 7 is configured of the bar code and the input signal set according to the white bar and the black bar. The signals are compared and the result is input to the microcomputer 8 as a digital signal.

Accordingly, the microcomputer 8 analyzes the digital signal input from the comparator 7, removes the start bar signal and the end bar signal, stores only pure data codes in the memory unit 9, and clocks the stored data. In synchronization with the clock pulse of the unit (1), the signal is sent to the host computer 10.

However, such a conventional barcode scanner, when the light reflected from the barcode is input to the image pickup device through the lens, if the light is too strong, the image pickup device is saturated, if too weak it is difficult to amplify the signal output from the image pickup device.

Also, the amount of reflection of light varies depending on the material on which the barcode is printed and the color of the barcode, and the amount of light incident on the image pickup device varies depending on the location of the lens, image pickup device, and light source. Not only was it difficult, but bar code analysis was impossible and mechanically required precision.

Accordingly, an object of the present invention is to provide a device for automatically adjusting the amount of light of a barcode scanner to automatically recognize a bar code at the most appropriate light brightness by automatically changing the light amount when scanning a bar code regardless of the reflected light amount of the material on which the bar code is printed and the position of the light source. Is in.

An object of the present invention is to count the oscillation frequency to any bit to generate a clock pulse of a certain period, and to select a predetermined number of bits from any bits generated from the clock generator to convert to an analog signal A digital / analog converting unit and a light generating unit converting a light quantity ratio according to the level of a signal output from the digital / analog changing unit and scanning the barcode into a bar code. The explanation is as follows.

FIG. 2 is a configuration diagram of an automatic light quantity adjusting device of the barcode scanner of the present invention, and FIG. 3 is a detailed configuration diagram of the clock generator of FIG. 2, and as shown therein, the frequency generated from the oscillator 1a is converted into an inverter. In the clock generation section 1 and the clock generation section 1, the waveform shaping is performed by the gate 1b, and the waveform shaping clock is divided at an arbitrary rate through the counter 1C to generate clock pulses of a predetermined period. The amount of light is selected according to the sawtooth waveform level converted from the digital / analog converter 11 and the digital / analog converter 11 that selects a predetermined number of bits from the generated random bits and converts them into a sawtooth waveform of a predetermined period. A light generator 2 for changing and scanning the barcode 3, a lens 4 for condensing an optical signal reflected and reflected according to the black and white bars of the barcode 3, and the clock generator 1 Generated by) Image pickup device 5 for picking up the optical signal through the lens 4 according to the pulse and converting it into the corresponding electrical signal, and amplifying the electrical signal corresponding to the optical signal output from the image pickup device 5 to a predetermined level. A small signal amplifier 6 for outputting and a comparison signal 7 for comparing the signal of the barcode amplified by the small signal amplifier 6 with a reference signal set according to the black bar and the white bar and outputting the result as a digital signal. And the digital signal output from the comparator 7 are stored in the memory 9 and transmitted to the host computer 10 in synchronization with the clock pulse of the clock generator 1. And a microcomputer 8 for controlling the entire system operation of the barcode scanner.

In the drawings, reference numerals C1 and C2 are capacitors.

Referring to the operation, effects of the present invention configured as described above in detail.

In order to scan a barcode, if a few bits are taken from the random bits generated periodically by the clock generator 1 and input to the digital / analog converter 11, the digital / analog converter 11 receives the input clock pulse. Is converted into a sawtooth waveform of a certain period and applied to the light generating unit 2, the light generating unit 2 changes the brightness of the optical signal according to the level of the sawtooth waveform input from the digital / analog changing unit 11 The most suitable optical signal reflected from the barcode 3 is incident on the image pickup device 5 by scanning the barcode 3.

That is, this will be described with reference to FIGS. 4 to 6 as follows.

First, when the oscillation frequency is generated from the oscillator 1a of the clock generator 1, the inverter gate lb forms a waveform of the input oscillation frequency and inputs it to the clock terminal CLK of the counter unit 1c. The counter 1c of the unit 1 counts the input pulse to an arbitrary bit and outputs clock pulses of a predetermined period divided by the output terminals Q1-Q12, respectively.

The digital / analog converter 11 receives a clock pulse from an arbitrary bit output from the counter 1C, that is, an output terminal selected by the experimenter from among the output terminals Q1-Q12 of the counter 1C. The light signal of the light generator 2 is changed by converting into a sawtooth waveform of a certain period.

For example, when an experimenter selects output terminals Q1, Q2, and Q3 among the output terminals Q1 to Q12 of the counter 1C, and connects them to the digital / analog converter 11, the output of the counter 1C is output. As shown in a of FIG. 4, at the terminal Q1, a clock pulse of a predetermined period is generated, and at the output terminal Q2, a clock pulse of a predetermined period divided by two of Q1 is divided into four divisions of Q1 at the output terminal Q3. Since the clock pulse is generated, the digital / analog converter 11 changes the clock pulse inputted from the output terminals Q1, Q2, and Q3 of the counter 1C into a sawtooth waveform having a rapid magnitude change in the level as shown in FIG. To be input to the light generating unit 2.

Accordingly, the light generator 2 rapidly changes the brightness of the optical signal according to the level change of the sawtooth waveform input from the digital / analog converter 11 to scan the barcode 3.

As another example, when the experimenter selects the output terminals Q1, Q3 and Q4 of the counter machine 1C and connects them to the digital / analog converter 11, as described above, the output terminal Q4 of the counter machine 1C. In FIG. 5, since the clock pulses of a predetermined period of 8 divided by Q1 are generated as shown in FIG. 5A, the digital / analog converter 11 performs the clock input from the output terminals Q1, Q3, Q4 of the counter 1C. By converting the pulse into a sawtooth waveform in which the magnitude change of the level as shown in b of FIG. 5 is changed irregularly, the light generator 2 inputs the optical signal in accordance with the level change of the input sawtooth waveform. Irregularly changes the brightness of the bar code 3 to be scanned.

As another example, when the experimenter selects the output terminals Q1, Q2, Q3, and Q4 of the counter machine 1C and connects them to the digital / analog converter 11, the output terminal Q1 of the counter machine 1C is provided at the output terminal Q1. As shown in Fig. 6A, a clock pulse of a certain period is generated, and a clock pulse divided by 4 of Q1 is generated at the output terminal Q3, and a clock pulse divided by 8 at Q1 is generated at the output terminal Q4. (11) converts the input clock pulse into a sawtooth waveform in which the magnitude change of the level as shown in b of FIG. 6 is converted slowly, and inputs it to the light generator 2, whereby the light generator 2 The brightness is changed slowly to scan the barcode 3.

As such, when the most suitable optical signal is selected by the experimenter and reflected through the barcode 3, the lens 4 collects the incident optical signal reflected by the barcode 3 and inputs it to the image pickup device 5. The device 5 captures an optical signal input at the most appropriate brightness at a moment in synchronization with the clock of the clock generator 1 and converts the optical signal into a corresponding electrical signal.

The signal output from the image pickup device 5 is amplified by the small signal amplifier 6 and input to the comparator 7, and the comparator 7 is a reference signal set according to the white bar and the black bar of the barcode 3. And compare the input signal with the barcode and input the result to the microcomputer 8 as a digital signal.

Therefore, the microcomputer 8 analyzes the digital signal input from the comparator 7 to remove the start bar signal and the end bar signal, and stores only pure bar code data in the memory unit 9 and stores the stored data in a clock generator ( The clock is sent to the host computer 10 in synchronization with the clock of 1).

As described in detail above, the present invention analyzes the barcode at the most appropriate light source brightness by automatically adjusting the light source brightness of the barcode scanner, thereby accurately recognizing the barcode regardless of the reflected light amount of the material on which the barcode is printed and the position of the light source. In addition, mechanically, there is an effect that high precision is not required as in a general barcode scanner.

Claims (2)

A lens 4 for collecting the incident light signal reflected by the black bar and the white bar of the barcode 3 and an optical signal through the lens 4 according to the clock pulse generated by the clock generator 1 An image pickup device 5 for converting into an electrical signal corresponding thereto, a small signal amplifier 6 for amplifying and outputting an electrical signal corresponding to an optical signal output from the image pickup device 5 to a predetermined level, and the small signal The comparison unit 7 which compares the signal of the barcode amplified by the amplification unit 6 with the reference signal set according to the black bar and the white bar, and outputs the result as a digital signal, and the digital signal output from the comparison unit 7. The microcomputer 8 which stores the data in the memory unit 9 and transmits the stored data to the host computer 10 in synchronization with the clock pulse of the clock generator 1 and controls the entire operation of the barcode scanner. Equipped with a barcode scanner system Then, a clock generator for waveform shaping the frequency generated from the oscillator 1a to the inverter gate 1b and dividing the waveform-shaped clock by an arbitrary multiple through the counter 1C to generate clock pulses of a predetermined period. 1), a digital / analog converter 11 for selecting a predetermined number of bits from any of the bits generated by the clock generator 1 and converting the same to a sawtooth analog signal of a predetermined period; and the digital / analog converter. A light quantity automatic adjustment device of a barcode scanner, characterized by comprising a light generating unit (2) which scans a barcode (3) by changing the quantity of light according to the sawtooth wave signal level converted from (11). The apparatus according to claim 1, wherein the predetermined number of bits selected by the digital / analog converter is at least one bit.