US 5,393,968 A · Method and device for reading bar code

Abstract

The present invention relates to a bar code reading method and a bar code reader applied preferably to POS systems used in the distribution industry. The object of the invention is to achieve an improved reading ratio or a reduced erroneous reading ratio in practical use by evaluating quantitatively the reliability of demodulation data and by performing a coincidence checking plural times only when a large error is recognized. When a reading distortion amount measured is within a predetermined allowable value, data extracted and demodulated from the bar code is judged to be valid, whereby the bar code reading is completed. When a reading distortion amount measured is not within the predetermined allowable value, if the same data from the bar code is extracted and demodulated continuously and at least twice, the same data extracted and demodulated from the bar code is judged to be valid, whereby the bar code reading is completed.

Claims24

Dependent claims

A bar code reading method wherein a beam light is irradiated and scanned to a bar code and data of the bar code is extracted and demodulated based on the light amount of a reflection light of said beam light, comprising the steps of:

measuring a reading distortion amount of said bar code;
judging data extracted and demodulated from said bar code as valid data when said reading distortion amount measured is within a predetermined allowance range, whereby said bar code reading is completed;
and
judging data extracted and demodulated from said bar code as valid data if said data from said bar code is extracted and demodulated continuously and at least twice when said reading distortion amount measured is not within said predetermined allowance range, whereby said bar code reading is completed.

1 more element

A bar code reader comprising:

a light source for emitting a beam light;
scanning means for scanning said beam light from said light source to irradiate to a bar code;
photoelectric converting means for receiving a reflection light of said beam light from said bar code to convert it into an electric signal corresponding to the light amount thereof;
and
demodulating means for extracting and demodulating data of said bar code based on said electric signal from said photoelectric converting means;
said demodulating means including:
distortion amount measuring means for calculating and measuring the reading distortion amount of said bar code;
and
judging means for judging whether said reading distortion amount calculated and measured by said distortion amount measuring means is within a predetermined allowable range or not;
whereby said demodulating means judges that the data extracted and demodulated from said bar code is valid when said judging means judges that said reading distortion amount is within said allowable range, and then completes the bar code reading operation;
whereby said demodulating means judges that the data extracted and demodulated from said bar code is valid only when the data of said bar code can be extracted and demodulated continuously and at least twice when said judging means judges that said reading distortion amount is not within said allowable range, and then completes the bar code reading operation.

8 more elements

Dependencies are inferred from the claim text.

Method and device for reading bar code

Life of this patent

Method and device for reading bar code

Life of this patent

Abstract

Claims24