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US 4,101,931 AGranted
Silicon diode array vidicon with electronically controlled sensitivity
AssigneeHughes Aircraft Company
InventorLeon S. Yaggy
Life of this patent
Estimating the term…
Abstract
Silicon diode array target sensitivity is made adjustable over a wide range by retracing the reading electron beam in the erase mode for each line, a variable number of scan periods ahead of its being read.
Claims11
A method of electronically selecting the sensitivity of an imaging device having a silicon diode array target comprising steps of:
- (a) exposing the front of said target to an image;
- (b) periodically scanning successive lines on the back of said target with an erasing electron beam;
- (c) periodically scanning each of said successive target lines with a reading electron beam a uniform time after it has been scanned by said erasing electron beam;
- and
- (d) selecting the time lag of said scanning electron beam relative to said erasing electron beam to attain a desired sensitivity for said imaging device.
2 more elements
A method of electronically varying the sensitivity of an imaging device having a semiconductor target with an array of diodes covering the rear surface of said target comprising the steps of:
- (a) exposing the front of said target to an image;
- (b) periodically scanning successive lines across the back of said target with a reading electron beam at a given current level;
- (c) retracing said electron beam at an elevated current level across the back of said target during periods intervening between successive ones of said scannings, the retracing that follows each scanning occurring along a line to be swept a uniform number of scannings thereafter;
- and
- (d) altering said uniform number to adjust the sensitivity of said imaging device.
2 more elements
An imaging device comprising in combination:
- (a) a semiconductor target disk having a front surface for receiving a projected image and a rear surface covered with an array of diodes;
- (b) means for projecting a beam of electrons at said target rear surface;
- and
- (c) means for periodically read-scanning said beam of electrons along successive lines forming a field on said target rear surface so as to read charges stored in diodes traversed by said beam and for periodically erase-scanning said beam across said lines so as to recharge said diodes prior to next reading them, each erase-scanning of a line in a given field preceding by a uniform time interval the next read-scanning of said line in the same field.
1 more element
An imaging device comprising in combination:
- (a) a semiconductor target disk having a front surface for receiving a projected image and a rear surface covered with an array of diodes;
- (b) means for projecting a beam of electrons at said target rear surface;
- (c) means for periodically read-scanning said beam of electrons along successive lines on said target rear surface so as to read charges stored in diodes traversed by said beam and for periodically erase-scanning said beam across said lines so as to recharge said diodes prior to next reading them, each erase-scanning of a line preceding by a unform time interval the next read-scanning of said line:
- and
- (d) means for adjusting said uniform time interval to alter the sensitivity of said imaging device.
2 more elements
An imaging device comprising in combination:
- (a) an evacuated envelope having a radiation transmissive window;
- (b) a charge storing target comprised of a silicon disk having a front surface facing said window and a back surface containing an array of junction diodes;
- (c) means facing said back surface for generating a beam of electrons;
- (d) means for scanning said beam of electrons along successive lines across the back surface of said disk at a given current level so as to read charges stored in diodes traversed by said beam;
- (e) means for retracing said electron beam during periods intervening between successive ones said scannings so as to charge diodes in the path of said retraced beam, the scanning of each line by said beam lagging the charging of that line by the retrace beam by a predetermined number of scanning intervals;
- (f) means for maintaining the current level of said electron beam higher during said retracings than during said scannings;
- and
- (g) means for varying the number of scanning intervals by which the reading of a given target line lags the charging of that line.
5 more elements
A method of operating an imaging device having a semiconductor target with an array of diodes covering its rear surface, an electron beam generator aimed at said diodes, vertical electron beam deflecting elements and horizontal beam deflecting elements comprising the steps of:
- (a) applying a periodically recurring horizontal deflection voltage ramp having a trailing edge which is steep relative to its leading edge to said horizontal beam deflecting elements to alternately scan and retrace said electron beam across the rear surface of said target;
- (b) alternately applying two identical, periodically recurring vertical deflection voltage ramps to said vertical beam deflecting elements so that one of said vertical deflection voltage ramps coincides with the leading edge of said horizontal deflection voltage ramp and the other of said vertical deflection voltage ramps coincides with the trailing edge of said horizontal deflection voltage ramp;
- (c) varying the phase of one of said vertical deflection voltage ramps relative to the other;
- and
- (d) applying a control signal to said electron beam generator in synchronism with said horizontal voltage ramp so as to raise the current level of said electron beam during the trailing edges of said horizontal voltage ramp above its current level during the leading edges of said horizontal voltage ramp.
2 more elements
Dependencies are inferred from the claim text.