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:
Nov. 21, 1989
Filed:
Sep. 10, 1986
Jonathan R White, Cedar Rapids, IA (US);
Norand Corporation, Cedar Rapids, IA (US);
Abstract
In laser bar code scanners bright sunlight tends to overpower the reflected laser light, drastically reducing the difference between bar code and background signals. In the present bar code reader, a plurality of light detectors are utilized with different spectral response characteristics at the wavelength of the incident laser beam, such that the differential response of the detectors tends to minimize the effect of background illumination. Narrowband optical filters with offset passbands may be used with conventional light sensors. As another example, filters with long wavelength transmission characteristics and offset cutoff wavelengths may be employed if necessary with a neutral density filter to provide balanced responses under broadband illumination.