The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 22, 1998
Filed:
Mar. 20, 1996
Edward P Coleman, Fairport, NY (US);
PSC, Inc., Webster, NY (US);
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.