GB683598A - Improvements in or relating to cathode ray image reproducing devices - Google Patents

Abstract

683,598. Cathode-ray tubes. RAULAND CORPORATION. June 22, 1951 [June 23, 1950], No. 14878/51. Drawings to Specification. Class 39(i) An image reproducing cathode ray tube has a fluorescent screen formed on a glass viewing window and constructed to have low reflectivity in accordance with the principles set out in Specification 683,597, wherein both the inner and the outer surfaces of the window are formed with nodular protuberances, having a height of 5-10 microns and a diameter of 25-100 microns. Both surfaces of the window may be formed by any of the methods disclosed in Specification 683,596, [Group XX], and 683,597'as applied to the outer surface only and the fluorescent screen is formed as a coating on the inner surface thereof. For glass bulb tubes the reflectivity of the window is 0.5 to 2 per cent of that of a mirror surface and the nodules 5-10 microns in height and 25-100 microns in diameter. Since the window varies in thickness, being thicker at the edges than at the centre, the reflectivity is made higher than would be necessary at the centre to maintain acceptable definition over the whole picture. For metal cone' tubes the glass window is thinner and of more uniform thickness than in the glass bulb type and suitable parameters are a reflectivity of 0.5- 1.5 per cent of that of a mirror surface and nodule dimensions of 5-10 microns in height and 25-50 microns in diameter.