基本信息
摘要：658,961. Cathode-ray tubes. RADIO COR- .PORATION OF AMERICA. Sept. 29, 1947, No. 26288. Convention date, Sept. 27, 1946. [Class 39 (i)] The target electrode of a cathode-ray storage tube comprises a conducting element, a first layer of insulating material and a second layer of insulation material joining the first layer to the conducting layer, electrons with a sufficient velocity impinging on and passing through the first layer to produce a trapped charge image which can be sensed by electrons impinging on said target with less than the said sufficient velocity. The target comprises a metal plate 1 having thereon a peaked layer 21 of high dielectric material of several times the thickness which stops electrons of less than 5000 volts e.g. a barium and strontium titanate mixture applied by settling from a suspension. A thin film of collodion is applied by immersing in water and applying a drop or so of collodion which spreads over the tops 5 of the titanate crystals. A silicon dioxide film 4 is formed by evaporation, and on subsequent heating the silicon dioxide layer settles on to the crystal peaks 5 and the collodion is evaporated. The target T is mounted in a tube 7 with two electron guns 8, 9 with corresponding electromagnetic or electrostatic scanning units 10, 11. Gun 8 produces an electron beam B1 having velocities greater than 5000 v., and gun 9 a beam B2 with velocities below 5000 v. The unit 10 of the put-on beam B1 scans radially from saw-tooth generators G1, rotation of the deflection yoke changing the radial direction and the unit 11 is connected to saw-tooth generators G2. Signals are applied to the put-on beam B1 in which the electrons are fast enough to penetrate the silica layer 4 and build up a charge image on the back of the silicate layer by secondary emission from the titanate layer 2, the secondary electrons being too weak to pass through silica layer. The take-off beam B2 liberates secondary electrons from the silica layer (which it does not penetrate) and requires a large number of scansions to remove the charge laid down by B1. Signals taken from the collector anode 12 or from the signal plate 1 are fed to a kinescope and built up to a bright image. The target may be photosensitive so that a map or printed information may be projected thereon, e.g..in a radar system.
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