GB549890A - Electron camera - Google Patents

Abstract

549,890. Electron image dissectors ; television. STANDARD TELEPHONES & CABLES, Ltd. Sept. 19, 1941, No. 12064. Convention date, Sept. 24, 1940. [Classes 39 (i) and 40 (iii)] In an electron camera of the image dissector type used to scan a motion-picture film in successive transverse lines-the film movement providing the " frame " scanning movement - the effect of an irregularity on the photo-sensitive screen is reduced by (i) distorting an elemental strip of the picture or (ii) moving the optical strip image about the screen. (i) By means of a light 12, Fig. 1, and an optical system 13, 14 a portion of the film 10 which is moving over the rollers 40, 41 is focused on a diaphragm 15 with slit 16 ; a further convex lens 17 and concave cylinder 18 is used to produce a wide distorted picture of this slit on the photo sensitive screen 19 the emission from which is scanned over a slit 21 or square aperture in the dissector tube 22. The electron image is received on the output electrode 23, which may be connected to the signal resistance 24 directly or through an electron multiplier. The lenses 17, 18 may be placed next to the lens 14 the diaphragm 15 being omitted. (ii) The optical image of the slit 16 is moved up and down the screen by a pair of prisms 42, 43, Fig. 2, rotating in opposite directions or by a glass plate with plane parallel faces and tilted about a horizontal axis. In this form also the diaphragm 15 may be dispensed with. In addition to the electromagnetic means 28 for scanning the electron optical picture across the slit 21, Fig. 1, or aperture 46, Fig. 2, in this second arrangement a further focusing device is used consisting of an electromagnet 44, which acts in synchronism with the movement of the prisms 42, 43 or plane glass plate to bring the electron optical line emission as it moves about the screen in all cases to the level of aperture 46 as it arrives at the dissector tube. The Specification as open to inspection under Sect. 91 states that the invention is applicable to iconoscopes. This subject-matter does not appear in the Specification as accepted.