JPH0581461A - Signal processing system for bar code scanner - Google Patents

Abstract

PURPOSE:To provide the signal processing system of a bar code scanner which is provided with the erroneous read preventing function which prevents erroneous read at the time of the occurrence of total reflection of scanning light. CONSTITUTION:This signal processing system of a bar code scanner is provided with a CCD element 1, an analog amplifying part 2, an analog/digital conversion part 3, and a control part 4 and decodes a bar code. A level detecting part 5 which detects the output level of the CCD element 1 is provided. The control part 4 is provided with the erroneous read preventing function which invalidates the digital signal from the analog/digital conversion part 3 to prevent erroneous read of the bar code at the time of detecting it by the level detecting part 5 that the output level of the CCD element 1 exceeds a prescribed level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing system of a bar code scanner having an erroneous reading preventing function for preventing erroneous reading when total reflection occurs in scanning light obtained by scanning a bar code.

[0002]

2. Description of the Related Art Generally, a bar code scanner forms an image of scanning light of a bar code on a CCD element (charge coupled device), converts it into an electric signal, amplifies the scanning light converted into the electric signal, and further, an analog signal. .Converting to a digital signal from a digital converter and converting the converted digital signal to CP
It is configured so that it is processed by a control unit composed of U, converted into a character, and the barcode is decoded.

[0003]

In the bar code scanner configured as described above, when the level of the analog signal changes due to total reflection, the analog signal is converted into a digital signal and processed by the control unit to process the character. When converted to, there is a risk that it will be converted to the wrong character.

The present invention has been made in view of the above points, and provides a signal processing system for a bar code scanner having an erroneous reading prevention function for preventing erroneous reading when total reflection of scanning light occurs in the bar code scanner. The purpose is to do.

[0005]

In order to solve the above problems, the present invention provides a signal processing system for a bar code scanner,
A level detector for detecting the output level of the CCD element is provided, and the controller invalidates the digital signal from the analog / digital converter when the level detector detects that the output level of the CCD element exceeds a predetermined level. It is characterized by having an erroneous reading prevention function for preventing erroneous reading of barcodes.

[0006]

According to the present invention, by configuring the signal processing system of the bar code scanner as described above, when total reflection occurs in the scanning light, the output level of the CCD element exceeds a predetermined level. When it is detected that the predetermined level is exceeded, the misreading prevention function of the control unit is activated and the digital signal from the analog-digital converter is invalidated, so that the misreading of the bar code can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a bar code scanner to which the signal processing system of the present invention is applied. In FIG. 1, reference numeral 1 denotes a bar code scanning light, that is, a light emitted from a light emitting element such as a light emitting diode to a bar code label surface, and the light reflected by the label surface and returned is converted into an electric signal C
CD element, 2 is an analog amplification section for amplifying the output of the CCD element, 3 is an analog / digital conversion section for converting the analog output of the analog amplification section 2 into a digital signal, and 4 is digital for the analog / digital conversion section 3. A control unit 5 having various functions such as a function of processing an output to decode a bar code, a function of transmitting the decoded signal to another device and a misreading prevention function described later, and 5 detect an output level of the CCD element. It is the level detection unit 5. In addition,
The control unit 4 has a CPU.

In the bar code scanner having the above structure,
If the scanning light of the barcode is normal scanning light, CCD
The analog output of the element 1 is amplified by the analog amplifier 2,
The analog / digital conversion unit 3 converts the signal into a digital signal and sends it to the control unit 4. On the other hand, the level detector 5 is CC
Since the analog output of the D element 1 is at the normal scanning light level, the output signal is not output to the control unit 4. The control unit 4 processes the digital output of the analog-to-digital conversion unit 3 to convert it into a character, decodes the bar code, and transmits the decoded character signal to another device.

When the totally reflected light is generated in the scanning light and the output of the CCD 1 exceeds the normal scanning light level, the level detecting section 5 detects the totally reflected light and the detected signal is a digital signal. Output to the control unit 4. When the control unit 4 receives this detection signal from the level detection unit 5, it invalidates the digital output of the analog / digital conversion unit 3. This can prevent erroneous reading of the bar code when the scanning light is totally reflected.

FIG. 2 is a block diagram showing the configuration of a bar code scanner that embodies the analog amplifier 2 and the level detector 5 of FIG. As shown in FIG. 2, the analog amplification section 2 is composed of an operational amplifier, and the level detection section 5 is composed of a reference voltage generation circuit 5-1 and a comparator 5-2. C
The analog output of the CD element 1 is input to one input terminal of the comparator 5-2, and the reference value of a predetermined level from the reference voltage generating circuit 5-1 is input to the other input terminal of the comparator 5-2. .. The comparator 5-2 outputs a detection signal of a digital signal to the control unit 4 when the analog output of the CCD element 1 exceeds the reference value from the reference voltage generation circuit 5-1.

Next, the operation of the bar code scanner of FIG. 2 will be described with reference to the waveform diagram of FIG. When the scanning light is normal, the waveform of the analog output of CCD element 1 is shown in FIG.
The waveform of the analog output when the total reflection occurs is as shown in FIG. 3B, and the portion where the total reflection occurs exceeds the level of the reference value Ls from the reference voltage generation circuit 5-1. .. Therefore, the comparator 5-2 is shown in FIG.
A detection signal having a waveform as shown in (c) is output to the control unit 4.

FIG. 4 is a flow chart showing the flow of signal processing of the control unit 4. First, in step ST1, the digital output of the analog / digital converter 3 is read to read the output signal of the CCD element 1. Next, in step ST2, it is determined whether or not the output of the CCD element 1 has total reflection, that is, whether or not there is the output of the level detection unit 5. If there is no total reflection, then in step ST3,
The bar code is analyzed to decode the bar code, and the decoded data is sent to another device in step ST4. In step ST2, if there is total reflection, the barcode analysis process is not performed, and the process returns to step ST1 to repeat the process.

The signal processing system of the bar code scanner of the present invention can be applied to touch type, pen type and fixed type bar code scanners.

In the above embodiment, the output of the CCD element 1 is directly input to the level detecting section 5, but the input to the level detecting section 5 is not limited to this. For example, the analog amplifying section 2 is used. From the middle part of the analog amplifier 2
It is also possible to input from the output unit of. The point is that a signal representing the output level of the CCD element 1 can be input to the level detection section 5, and the level detection section 5 can determine whether or not the output level of the CCD element 1 exceeds a predetermined level.

[0015]

As described above, according to the present invention, C
A level detector for detecting the output level of the CD element is provided,
The control section has a misreading prevention function for invalidating the output of the CCD element when the level detection section detects that the output level of the CCD element exceeds a predetermined level, and therefore the following excellent effects are obtained.

(1) It is possible to prevent erroneous reading when total reflection occurs. (2) Since there is no erroneous reading, the reliability of the output data of the barcode scanner is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a bar code scanner to which a signal processing system of the present invention is applied.

FIG. 2 is a block diagram showing a specific configuration example of a barcode scanner to which the signal processing system of the present invention is applied.

FIG. 3 is a waveform diagram showing waveforms of signals of respective parts in FIG.

FIG. 4 is a flowchart showing a flow of signal processing of a control unit of the barcode scanner.

[Explanation of symbols]

 1 CCD element 2 analog amplifier 3 analog / digital converter 4 controller 5 level detector

Claims (1)

[Claims] 1. A CCD element for converting scanning light of a barcode into an electric signal, an analog amplifying section for amplifying an output of the CCD element, and an analog / digital converting section for converting an output of the analog amplifying section into a digital signal. And a level detection section for detecting the output level of the CCD element in the signal processing system of the bar code scanner for decoding the bar code, the control section for processing the digital signal from the analog / digital conversion section. When the level detection unit detects that the output level of the CCD element exceeds a predetermined level, the control unit invalidates the digital signal from the analog / digital conversion unit to prevent an erroneous reading of the bar code. A signal processing method for a bar code scanner, which is characterized by being provided.