JPH04242872A - Bar code reader - Google Patents

Abstract

PURPOSE:To obviate the difficulty of bar code label decoding and misdecoding by eliminating the influence of A/D conversion due to disturbance light. CONSTITUTION:A bar code label 18 is scanned by a scanning part 11, and its reflection light 19 is converted into an electric signal in a light receiving part 12 to be outputted. In a subtraction part 14, the output of a disturbance light receiving part 13 is subtracted from the output of the light receiving part 12 by taking a slice level set according to the level of the disturbance light as an argument value. The disturbance light receiving part 13 receives the only disturbance light 20 to be outputted. A subtraction part 14 outputs the only bar code label signal slicing and eliminating the disturbance light. The signal is amplified by a video amplifier part 15 and digitized by an A/D conversion part 16. Then it is recognized by a recognition part 17.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reading device.

0002

2. Description of the Related Art Generally, barcode reading devices are used as input devices for POS systems. Barcode symbols are used for input, and therefore accurate reading of the barcode symbols is required.

FIG. 2 is a block diagram of a conventional barcode reading device.

The barcode reading device shown in FIG. 2 includes a scanning section 1 that scans a barcode label 18 with a laser beam or the like.
1, a light receiving section 12 that receives the reflected light scanned by the scanning section 11 and converts it into an electric video signal, a video signal amplifying section 15 that amplifies the video signal output from the light receiving section 12, and a video signal amplifying section 15. an A/D converter 16 that A/D converts the output of the A/D converter 16 into a digital signal, and a recognition unit 17 that receives the output of the A/D converter 16 and decodes the content of the scanned barcode label 18. Become.

Note that FIG. 2 also shows reflected light 19 of the laser beam projected onto the barcode label 18 and disturbance light 20 received by the light receiving section 12 in addition to the reflected light.

[0006]

[Problems to be Solved by the Invention] In the conventional barcode reading device described above, the light receiving section that receives the reflected light from the barcode label also receives the reflected light from the barcode label and ambient light other than the reflected light. . This disturbance light affects the A/D conversion of the reflected light from the barcode label, causing erroneous conversion, which makes it difficult to decipher the barcode label signal or leads to misunderstandings. There are drawbacks.

[0007]

[Means for Solving the Problems] The barcode reading device of the present invention includes a disturbance light receiving section that receives only disturbance light included in reflected light from a barcode label, converts it into an electrical signal, and outputs it. and a subtraction section that subtracts and removes a slice level set corresponding to the output of the disturbance light receiving section from the received light output of reflected light including disturbance light.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

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

The embodiment shown in FIG. 1 has the same scanning section 11, light receiving section 12, video signal reciprocating section 15, and A/
In addition to the D conversion section 16 and the recognition section 17, there is a disturbance light receiving section 13 that receives only the disturbance light 20 and converts it into an electrical signal, and a subtraction section 14 that subtracts the output of the disturbance light receiving section 13 from the output of the light receiving section 12. It is composed of:

Next, the operation of this embodiment will be explained.

[0012] Scanning the barcode label, the reflected light 1
When receiving light 9 and converting it into an electrical signal, the disturbance light receiving section 20 also receives disturbance light 20, converts it into an electrical signal, and outputs it. The reflected light 19 from the barcode label 18 includes
Since the disturbance light 20 is also included, in the subtraction section 14, the light receiving section 1
The output of the disturbance light receiving section 13 is subtracted from the output of step 2. This subtraction is performed by slicing the output of the light receiving section 12 at a slice level set corresponding to the level of the disturbance light 20 and cutting out only the barcode label signal. As a result, the disturbance light signal is removed from the reflected light signal from the barcode label 18, this signal is amplified by the video signal amplification section 15, converted into a digital signal by the A/D conversion section 16, and sent to the recognition section 17 for decoding. .

[0013]

Effects of the Invention As explained above, the present invention removes ambient light from the reflected light of a barcode label and reads it, so that the barcode label can be read even if the barcode label is located in a place where a large amount of ambient light enters the light receiving section. This has the effect of making it possible to accurately extract and decipher.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional barcode reading device.

[Explanation of symbols]

11 Scanning section 12 Light receiving part 13 Disturbance light receiving section 14 Subtraction part 15 Video signal amplification section 16 A/D conversion section 17 Recognition section 18 Barcode label 19 Reflected light 20 Ambient light

Claims (1)

[Claims] 1. A disturbance light receiving section that receives only disturbance light included in reflected light from a barcode label, converts it into an electrical signal, and outputs it; A barcode reading device comprising: a subtraction unit that subtracts and removes a slice level set corresponding to the output of the light receiving unit as a subtraction value.