Importance

Loading Importance Indicators...

Abstract

A bar code scanner system includes a laser light source that periodically produces a light beam that is swept across a bar code label. The laser light source is periodically turned 'on' and 'off' according to a duty cycle. A detector produces a first electric signal representative of received bar code label reflected light and ambient light when the laser light source is on, and produces a second electric signal representative of received ambient light when the light source is 'off'. A demodulator circuit, coupled to the detector, provides a first gain to the first electric signal and provides a second gain to the second electric signal. The gains applied are selected such that the signal and signal component produced solely as a result of the ambient light will significantly cancel out one another when the signals are combined. A filter, coupled to the demodulator circuit, receives the electric signals from the demodulator circuit and reduces out-of-band signal components such as noise. When the duty cycle of the laser light source is equal to 50%, the first gain is equal to the inverse of the second gain.

Loading the Abstract Image...

First Claim