JPH0543152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a barcode reading device that optically scans a barcode using an image sensor and reads the barcode.

Prior Art The configuration of a conventional barcode reading device is shown in FIG. In FIG. 4, 41 is an image sensor that converts barcode data into a video signal, 42 is an amplifier circuit that amplifies the video signal, 43 is a waveform shaping circuit that removes noise components from the output of the amplifier circuit,
44 is a binarization circuit that converts the output waveform of the waveform shaping circuit into a digital signal level, 45 is a microprocessor that takes in the output of the binarization circuit and performs barcode decoding processing, and 46 outputs drive pulses for the image sensor. timing generation circuit, 47
48 is a peak hold circuit that detects and holds the peak value of the output of the waveform shaping circuit, and 48 is an A/D converter that converts the peak hold output into a digital signal level. When reading a barcode label with a barcode reading device that uses an image sensor, in order to prevent the same barcode label from being read twice, a process to detect when the barcode label is removed from the field of view of the image sensor and a process to prevent duplicate readings are implemented. conduct. FIG. 5 shows the operation flow of the barcode reading device using an image sensor. After reading the barcode, the peak value of the video signal of the barcode label (a in FIG. 6a) is detected by the peak hold circuit 47, and the peak value is converted to a digital signal level by the A/D converter 48. The data is taken into the microprocessor 5 through the port 49 and stored. Thereafter, the microprocessor 45 repeats the peak value detection and capture processing of the video signal, and when the captured value becomes smaller than the stored value, it determines that the read barcode label has moved out of the field of view of the image sensor. was.

Problems to be Solved by the Invention However, in order to detect the peak value of the video signal and input it into the microprocessor 45, additional circuits such as a peak hold circuit 47 and an A/D converter 48 are required. When disturbance light such as illumination light enters the field of view of the image sensor, the video signal output has a waveform as shown in Figure 6b, and if the peak value A becomes larger than the peak value A in Figure 6a, The barcode reading device has a drawback in that it cannot determine whether the barcode label has moved out of the field of view of the image sensor.

Means for Solving the Problems A barcode reading device of the present invention for solving the above problems includes an image sensor that scans a barcode and converts it into a video signal, the image sensor, and an output signal of the image sensor. an amplifier circuit that amplifies a video signal; a waveform shaping circuit that removes low frequency component noise and high frequency component noise from the output of the amplifier circuit; and a binarization circuit that converts the output of the waveform shaping circuit into a digital signal level; and a microprocessor that takes in the output of the binarization circuit and decodes the barcode, and after the barcode decoding process is completed, the microprocessor
a first means for capturing the output of the binarization circuit into the microprocessor again; a second means for counting the number of bars of the captured data; and a third means for determining whether the count value is smaller than a predetermined value. The barcode label is provided with a means for determining whether the barcode label is out of the field of view of the image sensor when the determination result is small continuously for a predetermined number of times or more.

Effect With the above configuration, in order to determine the presence or absence of a barcode label from the bar number detection state of the video signal output from the image sensor, a peak hold circuit, an A/D
It is possible to detect that the barcode label has moved out of the field of view without using an additional circuit such as a converter, and even when ambient light enters the field of view of the image sensor.

Embodiment FIG. 1 is a block diagram of an embodiment of a barcode reading device of the present invention. In FIG. 1, 1 is an image sensor, 2 is an amplifier circuit that amplifies the output of the image sensor 1, 3 is a waveform shaping circuit that removes noise components from the output of the amplifier circuit 2, and 4 is a waveform shaping circuit 3.
5 is a microprocessor that performs barcode decoding processing; 51 is an input port that takes the output of the binarization circuit 4 into the microprocessor 5; 52 is a clock pulse output. The output port 6 is a timing generation circuit that generates an image sensor drive signal from the clock pulse. FIG. 2 is an example showing the configuration of FIG. 1 more specifically. The image sensor 1 uses a one-dimensional CCD (Charge Coupled Device), and includes an amplifier circuit 2, a waveform shaping circuit 3, and a binarization circuit 4.
consists of operational amplifiers, etc. 7 is a condensing lens that forms an image of the barcode label 8 on the image sensor 1. In the above configuration, barcode information imaged on the image sensor 1 is converted into a video signal by the image sensor 1 and amplified by the amplifier circuit 2. The output of the amplifier circuit 2 is sent to the waveform shaping circuit 3
High frequency component noise and low frequency component noise are removed from the signal, and the signal is converted to a digital signal level by a binarization circuit 4. In accordance with the flow shown in FIG. 3, the microprocessor 5 first takes in the output of the binarization circuit 4 (step I) and decodes the barcode label 8 (step). In the step, if decoding is impossible, the output of the binarization circuit 4 is taken in again and the bar code label 8 is decoded. In the step, when the decoding is completed, the loop counter x is cleared (x = 0) (step) and the output of the binarization circuit 4 is taken in (step). (step) and a third means to compare the count result with a predetermined value m (step). If the count value is less than or equal to m, the loop counter is incremented by (x+1) (step), and the same process (step) is repeated until the value x of the loop counter becomes greater than a predetermined value n. In the above-described repeated processing, if the comparison result is "small" n times in a row, the barcode label 8 is
It is determined that the barcode is out of the field of view, and the barcode reading process is terminated (step X).

In this example, as a result of reading tests on approximately 100 barcode labels, there was only 1 duplicate reading.
It never occurred.

Effects of the Invention As described above, according to the present invention, even after reading a barcode label, there is an excellent effect of preventing the same code from being read repeatedly.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a barcode reading device showing an embodiment of the present invention, FIG. 2 is a specific circuit diagram of the same device, FIG. 3 is a flowchart showing the processing operation of the device, and FIG. 5 is a block diagram of a conventional bar code reading device, FIG. 5 is a flowchart showing the processing operation of the device, and FIG. 6 is a signal waveform diagram of the main parts of the device. 1... Image sensor, 2... Amplification circuit, 3...
... Waveform shaping circuit, 4 ... Binarization circuit, 5 ... Microprocessor, 6 ... Timing generation circuit.

Claims (1)

[Claims] 1 An image sensor that scans a barcode and converts it into a video signal, an amplifier circuit that amplifies the video signal output from the image sensor, and waveform shaping that removes low frequency component noise and high frequency component noise from the output of the amplifier circuit. a binarization circuit that converts the output of the waveform shaping circuit into a digital signal level;
comprising a microprocessor that takes in the output of the binarization circuit and processes the barcode decoding;
After the barcode decoding process is completed, the microprocessor includes a first means for inputting the output of the binarization circuit into the microprocessor again, a second means for counting the number of bars of the input data, and a count value. is smaller than a predetermined value, and if the determination result is smaller than a predetermined number of times in succession, the bar code label is determined to have moved out of the field of view of the image sensor. Code reader.