GB1263668A - Cathode ray tube bistable storage apparatus - Google Patents

Abstract

1,263,668. Cathode-ray storage tubes. TEKTRONIX Inc. 1 April, 1970 [16 April, 1969], No. 15459/70. Heading H1D. In a cathode-ray storage tube comprising a high-velocity writing gun and a low-velocity flood gun adapted to produce secondary emission at the target to cause bi-stable storage of a charge image, the target comprises a dielectric layer 40, Fig. 3, deposited on a conductive layer 42 on a support 14 and is characterized by the provision of a collector electrode 44 in contact with the layer 42 and adapted to collect secondary electrons. The collector electrode 44 may be a mesh held at the optimum potential (+ 170 volts) for secondary electron collection, whilst the target electrode 42 is normally at earth potential and may be pulsed to + 200 V. to erase the charge image. This erasure takes 1 to 5 milliseconds, and is so fast that the erase electrode may be pulsed at 60 cycles to operate the tube in a non-storage mode. The target electrode 42 may be divided into two horizontal strips energized independently (Fig. 2, not shown), or into a number of vertical strips. The dielectric layer 40 is preferably a continuous phosphor layer to provide an optical output, but may comprise a number of islands of phosphor material or may comprise non-luminescent material, and the writing gun may also be used for reading to produce an electrical output from electrode 44. The electrode 44 is preferably of light-reflecting material such as aluminium to increase the brightness of the optical image, and may be coated on the phosphor by vapour deposition through a mask; it may comprise 200 lines/inch with an electron transmission of 80%. The substrate 14 may be a glass faceplate which is sealed to the ceramic envelope 58 with crystallized glass 60, with tin oxide coatings extending through the seal to form lead-in connections to electrodes 42 and 44. The tube may include two flood guns at earth potential and a writing gun at - 3000 V. (Fig. 1, not shown).