US 4,146,782 A · Decoder system for light pen bar code reader

Abstract

A manually supported reader for a bar code which comprises a plurality of parallel bars of varying widths employs an optical detector which generates an electrical output signal which is a function of the code as the detector is moved. The detector comprises a light source and a light sensor, optically arranged to reflect light off of that part of the bar code with which it is in contact, thereby varying the output signal of the detector each time a boundary of one of the bars within the code is traversed. A decoding network receives the output signal from the detector and determines the time required to traverse each successive bar. A signal associated with the traversal of each bar is compared with an internally generated criterian. As a result of the comparison, the bar associated therewith is classified as to its width. Based on that classification, the criterian is recalculated for comparison with the signal associated with the next bar scanned. The decoding circuitry can be implemented within computer software or hard wired.

Claims5

Dependent claims

A reader for bar codes which consist of a plurality of parallel bands of widths which fall within one of a plurality of fixed classifications comprising:

a sensor adapted to be manually moved across the bar code perpendicularly to the direction of extension of the bands and having an electric output signal with a characteristic which varies as a function of the properties of that portion of the code being instantaneously scanned;
decoding means operative to receive said electric output signal, generate a signal having a value which is a function of the time interval required for the sensor to traverse a band;
storage means for a criterion value;
comparator means operative to compare the criterion value retained in said storage means with said signal associated with said time to traverse a band, the output of said comparator means assigning said first band within one of said classifications;
and means for recalculating said criterion value based on said signal having a value which is a function of said time interval and the output of the comparator means;
whereby as each band after the first is scanned, the signal associated with that band is compared with a criterion value which is a function of the signal associated with the preceding band.

3 more elements

Dependencies are inferred from the claim text.

Decoder system for light pen bar code reader

Life of this patent

Decoder system for light pen bar code reader

Life of this patent

Abstract

Claims5