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:
Apr. 04, 1995
Filed:
Apr. 30, 1993
Keith E Cobbs, San Diego, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A phase plate adapted for use with an optical sensor module for an inkjet printer/plotter equipped with a photodetector to sense a test pattern having a plurality of horizontally spaced bars or vertically spaced bars and a photodetector. The inventive phase plate is in optical alignment with the photodetector and is constructed of opaque material. The phase plate includes a plurality of apertures horizontally spaced therein. The spacing between the apertures is equal to the spacing between the horizontally spaced bars in said test pattern. In the alternative, the plate may include a plurality of apertures vertically spaced therein. In this case, the spacing between the apertures is equal to the spacing between the vertically spaced bars in the test pattern. In a particular implementation, the phase plate includes both horizontally spaced apertures and vertically spaced apertures. In this case, the horizontal spacing between the apertures is equal to the spacing between the horizontally spaced bars in the test pattern and the spacing between the vertically spaced apertures is equal to the spacing between the vertically spaced bars in the test pattern.