Allen A Endres

US Patent:

49907654, Feb 5, 1991

Filed:

Nov 22, 1989

Appl. No.:

7/440779

Inventors:

Miroslav Ondris - Chagrin Falls OH
Allen A. Endres - Chagrin Falls OH

Assignee:

Stemcor Corporation - Cleveland OH

International Classification:

H01J 4014

US Classification:

2502082

Abstract:

A method and means for the electronic processing of an analog signal generated in a series addressed diode array to produce a digital signal indicative of the illumination of the photodiodes in the array is disclosed. A voltage ramp is applied to the array and the resulting current steps converted to a voltage signal. The voltage signal is differentiated and the resulting pulses are digitized to provide the illumination state of the photodiodes in the array. Alternately, the voltage signal is integrated in a series of windows. The results of each previous integration is substrated from the most current integration, producing a series of pulses that are digitized to provide the illumination state of the array. The processing may be synchronized by either dividing the sweep interval into evenly spaced intervals, by differentiating the voltage signal and detecting the derivative exceeding a threshold, or differentiating the voltage signal twice and detecting zero-crossings in the resulting signal. The voltage ramp may be made to increase in slope with time to help ensure that the addressing diodes begin conducting at equal time intervals.