Radiation shutters
AssigneeEnglish Electric Valve Company Limited
InventorRalph D. Nixon
Life of this patent
Estimating the term…
Abstract
A rotatable thermal shutter for use with a pyroelectric camera tube is provided with blades having opening and closing edges in the shape of a spiral. The use of a spiral shape allows the rotatable shutter to have a particularly small diameter while still providing satisfactory performance.
Claims11
A pyroelectric television camera arrangement including a camera tube and a rotatable radiation shutter mounted so as to be capable of modulating thermal radiation incident upon the camera tube, the shutter having a plurality of blade portions arranged symmetrically about its axis of rotation and having opening and closing edges in the shape of a spiral, the camera tube being orientated in relation to the blade portions so that the line scan direction of the television raster is substantially aligned with said opening and closing edges as the thermal radiation is modulated by rotation of the shutter.
In a pyroelectric television camera system, the combination of:
- a camera tube having an image-receiving target and means for periodically scanning said target, line by line, to obtain a useful video signal therefrom;
- a shutter mounted for rotation relative to said target, said shutter including window means defining spiral opening and closing edges for sweeping in front of said target respectively to unmask and mask said target progressively in a direction substantially perpendicular to the scanning direction;
- and
- means for rotating said shutter in synchronism with said scanning whereby the scan lines of said scanning track closely in front of said opening and closing edges.
Dependencies are inferred from the claim text.