Abstract: A color display tube which has a channel plate electron multiplier for multiplying a low voltage, low current electron beam and thereby obtaining an amplified output beam for producing an image on a screen formed of a plurality of different phosphors arranged as dots, each of which is surrounded by at least one ring. In order to form the output beam into well defined dots and rings to obtain good color purity, the source-to-screen distance of the output beam is varied in a predetermined manner. A means for doing this comprises additional electrodes mounted on the output side of the electron multiplier.

Abstract: A channel plate electron multiplier is mounted parallel to, but spaced from, the screen. The electron multiplier comprises a stack of juxtaposed substantially planar apertured dynodes with the apertures therein aligned to form channels. An apertured extractor electrode is mounted on the output side of the electron multiplier. Preferably two or more foraminous deflector electrodes are mounted on the extractor electrode. The apertures in the foraminous deflector electrodes have the same pitch as the channels of the electron multiplier but are offset laterally relative to each other and to the axes of the channels by amounts which allow the emergent electron beam from each channel to pass through to the screen without impinging upon the deflector electrodes. By applying a potential difference between the deflector electrodes an electron beam emerging from its respective channel is deflected laterally onto a respective one of its associated group of phosphor stripes.

Abstract: A cathode ray tube comprising a channel plate electron multiplier structure disposed between a source of electrons and an output device such as a cathodeoluminescent screen. The electron multiplier comprises a stack of n apertured dynodes which are separated from each other and are arranged in cascade with the apertures in adjacent dynodes aligned to form channels. In order to improve the resolution of the electron multiplier while enabling the dynodes to be aceptably rigid the axial profile of the apertures in at least the second to the (n-1)th dynodes is such that it comprises a re-entrant portion within the thickness of the dynode with the axially spaced ends of the re-entrant portion being spaced from the respective opposite surfaces of the dynode by a convergent or cylindrical input portion and a divergent or cylindrical output portion.

Abstract: A deflection color selection system for a single beam channel plate display tube includes, within an envelope 10, a laminated dynode channel plate electron multiplier (16) having channels whose exit apertures are aligned in columns. An apertured extractor electrode (36) is mounted on and electrically insulated from an output face of the electron multiplier (16), the apertures (42) in the extractor electrode (36) being aligned with respective channels. A luminescent screen (14) spaced from the extractor electrode (36) includes patterns of phosphor elements (R, G, B) adapted to luminesce in different colors.

Abstract: Channel plate image intensifiers, for use as raster intensifiers in cathode ray tubes for example, comprise a stack of alternately arranged perforate laminar dynodes M and perforate laminar separators D aligned to form electron multiplier channels P. Each of the separators comprise a perforate aluminium plate having an anodized layer some 15 microns thick on the plate surface. Such separators can be manufactured to have the desired electrical characteristics and uniform thickness over their entire area so that the dynodes M are parallel to each other and provide a uniform gain over their entire area.The invention also relates to a method of anodizing perforate and imperforate aluminium foils.