Low light level image pick-up tube arrangement
AssigneeThomson-CSF
InventorChristian Pepin
Life of this patent
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Abstract
A low light level image pick-up tube is protected from excessive illumination intensity damage by controlling a very high voltage assembly supplying the tube. The tube comprises in a preferred embodiment a plurality of image intensifier stages in cascade preceding an electron gun from which a video signal is provided by electronic scanning. A mean level video regulation circuit provides from the video signal an output signal used for controlling the supply voltage value to at least one of the image intensifier stages including the last one i.e. that preceding the electron gun. Further, a signal proportional to the supply current to the last image intensifier stage is used for controlling the supply voltage value of the input image intensifier stage which receives focussed radiation from an observed field.
Claims10
A low light level image pick-up tube arrangement comprising:
- optical means for focussing radiation received from an observed field;
- an image pick-up tube for receiving the said focussed radiation and for delivering a video signal, the said pick-up tube comprising image intensifying means which include a plurality of image intensifier stages in cascade, and electron gun means from which said video signal is derived by electronically scanning a target;
- very high voltage generating means for supplying said intensifier stages with supply voltages respectively;
- a mean level video signal regulation circuit receiving said video signal for providing a first control signal;
- said first control signal providing through said generating means a variation of the supply voltage to at least one of the said image intensifier stages including the last one i.e., that preceding the said electron gun means, and, a control circuit receiving a signal proportional to the supply current of the said last image intensifier stage for providing a second control signal, said second control signal providing through said generating means a variation of the supply voltage to the input image intensifier stage;
- said generating means comprising means for receiving said first and second control signals respectively and for controlling the magnitude of the supply voltages which feed said intensifier means.
Dependencies are inferred from the claim text.