Patent GB-1161832-A (GB)
Title: Gaseous Display and Memory Apparatus.
IPC: G09G3/294
Filed: 1967-01-12
Abstract: 1,161,832. Gas cell data stores; electric selective signalling; gaseous discharge monogrammic displays. UNIVERSITY OF ILLINOIS FOUNDATION. 12 Jan., 1967 [18 Jan., 1966], No. 1793/67. Headings G4C, G4H and G5C. [Also in Divisions H3 and H4] An information device comprises a plurality of gaseous discharge minicells each having a pair of electrodes conductively isolated from the minicell and including means for connection to a pulse source for forming wall charges in the minicell, the presence or absence of the wall charges imparting information. A storage OF display unit comprises a sandwich of three insulating glass plates the middle one of which has a matrix of holes (the minicells) filled with neon and 2-10% nitrogen at 315- 740 mm. Hg. pressure. The two outer plates bear row and column electrodes respectively on their outer faces, each intersection of a row and a column electrode corresponding to one hole (minicell). The unit may be R.F. shielded by an earthed conducting backing plate. A stack of such units may be provided. Various sinusoidal, pulse-type and exponential electric waveforms are described for (a) storing information in the minicells by causing a visible discharge which produces wall charges (the charges terminating the discharge); (b) regenerating the information; (c) reading it out non-destructively (by causing visible discharges in those minicells having wall charge, to form a visible display by repetitive read-out, or for input to a computer in which case the flashes of light are detected by phototubes); or (d) erasing it. Address selection in the matrix of minicells may be done by computer-controlled tree networks of gas cells selecting row and column electrodes. Charged particles within the cell to permit discharge may be supplied by a radio-active coating on the minicell walls, repetitive conditioning electric pulses applied to all minicells to create metastable atoms, or by the photo-electric effect. This latter possibility permits a picture to be digitized and stored by imaging it on the matrix of minicells or writing it using a light-pen. From the matrix it may be entered into a computer or optically printed. Alternatively information can be printed from the matrix after line-by-line build-up under computer control. The matrix of minicells can be used as a TV receiver display. The minicells of the matrix may be grouped into clusters, the minicells of a cluster being fronted by masks of different binary-weighted opacities to provide selected shades of grey (grey scale). Similarly phosphors within the minicells of such clusters and/or coloured masks fronting them permit colour TV. Alternatively different intensities may be obtained by varying the time the minicells are in given states (duty cycle technique). In an alphanumeric display, one set of electrodes may be shaped as lines of different inclinations, a combination of which can form any character required. Two chargepresent states could be used, controlled by respective electric waveforms, permitting greater storage density, or storage of two displays either of which could be actuated. The minicells in a matrix array need only be separated electrically so the matrix of holes would be replaced by a single large hole. Modulator (for producing a storage regeneration waveform). In Fig. 17, with transistors 152, 154 on and off respectively, transformers 150, 148 insert low and high impedances into LC circuits 142, 144 and 142, 146 respectively so that LC circuit 142, 144 is a tuned circuit driven via step-up transformer 158 to produce a sinusoid across capacitor 144. With transistors 152, 154 off and on respectively, LC circuit 142, 146 is tuned and only a small-amplitude sinusoidal ripple appears across capacitor 144 due to the large impedance now inserted by transformer 150. The on/off states of transistors 152, 154 may be reversed periodically.