Automatic exposure control circuit for an image intensifier camera
AssigneeThe United States of America as represented by the Secretary of the Army
InventorJohn A. D'Agostino
Life of this patent
Estimating the term…
Abstract
This invention relates to automatic exposure control for an image-intensiation photographic camera through the employment of a capacitor discharge circuit. The electrical energy stored in a capacitor is discharged to activate an image intensifier tube which forms part of the photographic camera system. The characteristics of the capacitor discharge circuit are chosen to correspond to the energy required for proper exposure time through the image intensifier tube and onto a photographic emulsion.
Claims1
In combination with a camera having an image intensifier tube including a photocathode, an anode and phosphor screen, and characterized by variable resistance that is a function of light intensity incident on the photocathode when the photocathode is exposed to light, an automatic exposure control system comprising:
- a direct current power source;
- a variable capacitor;
- and
- switching means operable for connecting said variable capacitor across said power source to charge said variable capacitor from said power source, and operable for disconnecting the charged variable capacitor from the power source and for connecting the charged variable capacitor in series with the photocathode and anode and phosphor screen for discharging said variable capacitor through said image intensifier tube and wherein the rate of discharge is dependent continuously on the light intensity incident to the photocathode during the discharge.
Dependencies are inferred from the claim text.