Patent GB-1173604-A (GB)
Title: Energy-Sensitive Luminous Display Device.
IPC: H05B33/12
Filed: 1966-10-24
Abstract: 1,173,604. Electroluminescence. MATSUSHITA ELECTRIC INDUSTRIAL CO. Ltd. 24 Oct., 1966 [25 Oct., 1965], No. 47644/66. Heading C4S. A luminous display device comprises a frequency selective RC network consisting of a parallel combination of a first resistance and first capacitance series connected with a second resistance and second capacitance, the first capacitance comprising an electroluminescent element and at least one of the resistances being photo-conductive or magnetoresistive, the R and C values and frequency of AC source being such that the device operates over a preselected portion of the frequency selection curve on energization of the variable resistances and/or on change of the frequency of the AC source. The capacitances may be photodiodes one of which is in parallel with the EL element (Fig. 1, not shown). The device may comprise layers in turn of photoconductive, opaque resistive, e.g. carbon particles in epoxy, dielectric and EL materials (Fig. 4, not shown). Visible and infra-red radiation are instanced and positive, negative, or mixed negativepositive output images depending on the portion of the selection curve operated upon. Fig. 9 includes quartz layer 100, stannic oxide layer 50, polyester resin layer 41, infra-red photo-conductive Si : Zn or Au layer 27, ZnS elements 26 which are vacuum evaporated, sintered or mixed with a plastic binder in strip or line form (dots also instanced), elements 28 of p.c. CdS : Cl or CdSe which may be sensitive to feedback radiation from elements 26, and gold electrodes 31 and 32. Bi-stable storage operation may be effected, black opaque paint on faces 33 and 34 prevents feedback and conductive deposits enhance electrical coupling. Elements 27 and 28 may be interchanged and the device illuminated on the face. Elements 28 and layer 27 may be the same p.c., e.g. an infra-fed light quenching p.c., and a thin glass or quartz layer included (Fig. 6, not shown). Electrodes 31 and 32 may be replaced by a grid array 47 of conductive paint or vacuum deposited material adjacent the inner face of an EL layer (26) of ZnS in plastic or glass enamel, a plurality of electrodes (30) adjacent the outer face of same, and the p.c. (25) may also be Ge (Fig. 11, not shown). The electrodes 31, 32 may be replaced by planar electrode (30) on the outer face and wire electrodes (47) embedded in p.c. layer of CdS on the inner face of EL elements (26) and interposed polyester resin regions (21) (Fig. 13, not shown). (Cd-Hg)Te p.c. and dielectric polyester resin layers are further included. The alternate electrodes (65), (35) of the lower grid electrodes may be adjacent the outer and inner faces of the EL and interposed SiO 2  dielectric elements (25) and (44) respectively and the grid electrodes (55) constituting the upper conductor adjacent the lower faces of the SiO 2  regions (Fig. 14 not shown). The device further includes only a PbS, PbSe or (Cd-Hg)Te p.c. layer (25) and borosilicate glass substrate (120). Spacer elements (44) may alternatively be p.c. and grid electrodes (35) may be on either outer face of the device. To prevent PbS deterioration a protective layer may be added or the device enclosed in a vessel fitted with inert gas or evacuated. In Fig. 16 (not shown), the p.c., EL, and dielectric components of Fig. 14, are continuous planar layers. In Fig. 17 (not shown), two sets of wire electrodes (55), (35) are arranged alternately in the p.c. layer (25), electrodes (55) being enclosed in a low loss dielectric such as a formaldehyde resin or glass enamel. Light transmissive plastic or light reflective titanium oxide may be included as spacers in EL layer (26), the outermost electrode (65) may be planar or metal wires covered by an EL material mixed with organic resin binder or glass enamel. Opaque layers may be included to prevent feedback. The variable resistances may be magnetoresistive InSb.