Film stabilizing system for electron beam recorder

Abstract

Abstract The invention is applicable to an electron beam recording system which includes a film transport for moving a film past a scanning window, the system including an electron sensitive plate positioned adjacent to the window, and means for scanning the modulated electron beam in a repetitive scanline pattern over a reference position which includes the plate and the window. In the system, the rate of scanning is synchronized with the motion of the film and the plate has an output which is a function of the intensity of the beam that is incident on an active area thereof. The invention comprises an improved subsystem for stabilizing the position of the beam with respect to the film. In accordance with the invention, there are provided interrupt means located at a prescribed position on the plate for causing an interruption signal on the output of the plate means when the electron beam is scanned over the prescribed position. Means are provided for comparing the interrupt signal to the timing of individual scanlines and for generating a correction signal which reflects the comparison. Finally, means are provided for varying the reference position of the scanline pattern in accordance with the correction signal. In a preferred embodiment of the invention, the interrupt means comprises a vertical slot in the plate. In this embodiment, the interrupt signal is used to sample a ramp voltage that is, in turn, synchronized with horizontal synchronizing pulses. The sampled voltage is applied to a sample and hold circuit which generates the correction signal for application to the horizontal centering circuitry of the electron beam scanner.

Inventors

• 👤 R Castrignano

Bibliographic Details