GB1314906A - Display devices - Google Patents

Abstract

1314906 Electrophoretic display device MATSUSHITA ELECTRIC INDUSTRIAL CO Ltd 12 June 1970 [12 June 1969 31 July 1969] 28584/70 Heading G5C [Also in Divisions C4 C5 and H1] A display device (flat, curved and/or flexible) comprises material the luminescence of which is controllable by electrophocetic movement. The device may include in suspension at least one electrophosetion material (26) Fig. 1 (not shown) which may itself luminescence green under one or both Áv sources (32) (33) (e.g. fluorescent, Hg or Xe lamps, sunlight or alternatively X-ray, γ-ray electron or α-particle sources) the colour on the respective anode cathode sides varying as then continuous or pulse D.C. voltage polarity (Figs. 1b and 1c, not shown), the suspension medium and for material (26) being visible light and/or radiation flux absorbent and/or reflective. The suspension medium may alternatively or also be luminescent, and half tone and other images controlled by duration, size and field polarity, A.C. or mechanical vibrations also restoring original colour. Excitation may be by radium, strontium 90, titium or promethium 147 included in suspension, or by an electric field, and. the solid or liquid suspension medium, a few Á or mms. thick, may include non-electrophoretic particles, a blue suspension being oil black dyes dissolved in ethyl acetate or herosene. Figs. 2a and 2b (not shown) includes luminescent (e.g. red) or non-luminescent porous layer (35) of cloth or mesh fabric of natural or artificial fibres; a fibroid sheet; or a granular sheet bonded with resin or adhesive. Figs. 3a, 3b (not shown) include electrophocetic materials 41, 42 of differing emissions (e.g. red, green) intensities and/or persistencies and polarities while Figs. 4a, 4b (not shown) include particles (45) (46) (e.g. yellow and blue) of same plarity but different nobilities. One electrode may be E-shaped as in Fig. 5, including suspension layer 50 which may be electroluminescent or may emit on incidence of flux, or a plurality S 1 -S 7 selectively energized (Fig. 6, not shown), a series of such units forming a display panel, or a cross-bar array used (Fig, 7, not shown) and cyclically scanned, fabrication being by electro deposition, evaporation, printing or photoetching. Fig. 8 (not shown) includes polyester, cellulose acetate, cellophane or polyethylene insulating housing (55) and movable electrode (57) which may be pen-like to produce a pattern or writing. Alternatively surface charging may be by charged particles such as ions or electrons, particle incidence or an A.C. or D.C. roller being used to erase. Porous layer (58) (Fig. 8, not shown) or a sheet (59) (Fig. 8b, not shown) with projections and of nylon is preferably included as mechanical spacer. The device may be included in a c.r.t. (Fig. 9, not shown), electrons from gun (61) depositing on insulator (55), radiation flux being directed through window (63) or wall (25), and erasure being by a suitable secondary emission characteristic of wall (55). Wall (55) may be replaceable by a wire mosaic of a thin glass sheet with transversely embedded wires. In Fig. 10 (not shown) with paper, metal or plastic base (65), high viscosity suspension (50) is softened by heating or a solvent to produce sufficient electrophoretic mobility during voltage application, a permanent pattern ensuing. Fluorescent materials may be organic or inorganic (e.g. pigments or dyes) such as oxide, sulphide, selenide, silicate, phosphate or tungstate of Ca, Ba, Mg, Zn, Cd or Sr, with Mn, Ag, Cu, Sb, Pb or Bi activator or diaminostilbene, fluorescein, thioflavine, cosine or rhodamine B dyes of size 0À1 to 50 Á. Non- luminescent electro phocetic material may be carbon black, graphite or titanium dioxide. Charge control, dispersion or stabilizing agents may be included and electrophocetic particles are preferably coated in a resin not soluble, or only partically so, in the suspension medium, in the latter case acting as fixing agent. Suspension media may be kerosene, trichlorotrifluoroethane, isopropyl alcohol, liquid paraffin, mineral or olive oil; for permanent display, beeswax, vegetable, paraffin or synthetic wax; or thermosetting linseed, soya or tung oil. Liquid suspensions may include polystyrol, vinyl acetate resin or linseed oil, hardening by pressure reduction to effect evaporation or extraction. Fig. 11 (not shown) includes vinyl acetate resin, polystyrol or gelatin insulating layer to assist electrophoretio material removal and improve electrical breakdown resistance. The layer may be cellular with spacer sheet (73) (Figs. 12 and 13, not shown) with square, circular, rectangular or hexagonal holes containing varying colour suspensions (e.g. red, green, blue) selectively energized, or black-greywhite suspension with different coloured filters. A cylindrical device (Fig. 14, not shown) includes A or Kr and Hg, emitting at 2537 Š on U.V. exutation. The inner cylinder may be fluorescent coated and employed as a fluorescent lamp. In examples, cyanide green B, olive oil, fluorescent particles in ZnS are excited by U.V. radiation or on E field and ZnS, with toluene and vinyl acetate resin coated on polyester fibre produces a porous layer, with propyl alcohol as suspension medium.