The Honeywell 610 then automati cally sequences valves to fill, heat, pressurize and depressurize (if neces sary), cool, and drain a beck. By teletype the computer calls for the proper formulations of dyes and chem icals, which are added automatically. It also tells the operator when to cut a patch (sample) for a color check. Depending on the color check, the dyer can then either direct the com puter to continue, or he can provide a modified programing sequence that continues until the next patch is cut. Throughout the dyeing process a teletype log is kept of process variables such as temperature, pressure, and pH, as well as dye and chemical use, equip ment use, and process delays. From this log a summary teletype selects and collates information of permanent value. This information permits rapid analyses of dyeing operations and serves as source data for cost account ing and control purposes. J. F. Magarahan, Lyman vice presi dent and general manager, estimates greater throughput—between 20 and 30%—has been achieved using the computer-controlled system. More over, with the computer, the company is able to document its dyeing experi ence and make this experience avail able for instant recall. Thus, the company can respond more rapidly to customer needs. According to Mr. Magarahan, Ly man has a five-year program to expand automatic control. The next s t e p computerization of Lyman's continu ous dyeing operations—is now under way.
Thin-film switches patent issues Energy Conversion Devices, Troy, Mich., has received a patent (U.S. 3,271,591) on thin-film switches which, the company says, may herald "an entirely different type of semicon ductor industry" equal in size to that which grew out of the development of the transistor 18 years ago. The pat ent, issued to ECD president Stan ford R. Ovshinsky and assigned to the company, covers devices which can be made to change from a conductive state to a nonconductive state by ap plying an electric field. Transistors and other present-day semiconductor devices are based on conduction through positive and neg ative junctions that are formed by doping high-purity crystals with pre cise amounts of impurities. ECD's thin-film switches, however, are com prised of a single, homogeneous film which can be applied to almost any substrate. When the applied voltage is below the device's threshold limit, the switch 32 C&EN OCT. 10, 1966
has a resistance of about 1 million ohms. When the voltage exceeds the threshold value, the resistance drops to less than 1 ohm. Switching speeds are about 0.1 microsecond. The company says the devices can be made from mixtures of a wide number of substances including ele mental and intermetallic semiconduc tors and other materials, such as alu minum, various metal oxides, and mixed valence transition metals—tan talum and iron, for example. The materials are mixed, fused at suitable temperatures, and either cast into pel lets or deposited as a thin film. The company foresees many ap plications for this concept. Because the switches are symmetrical (not subject to polarity), a single unit can be used for controlling alternating current. Present semiconductor de vices require two units in series to perform this function. When the film is applied to a metal substrate, the resultant heat sink effect allows han dling current up to 250 watts. In addition, if the applied voltage is held to a constant value just below the threshold, the device can act as a sensor amplifier. It can then be made to respond to changes in temperature, pressure, light intensity, or moisture content. But the biggest application for the switches, E C D feels, will probably be in integrated circuits, where they can be applied the same way as passive components such as resistors and ca pacitors. This application will then permit integrated circuits to duplicate transistor and diode functions. ECD has licensed the development to International Telephone and Tele graph and its British affiliate, Standard Telephone & Cables, Ltd., and to L. M. Ericsson & Co. of Sweden and Danfoss, A.S., of Denmark.
Stanford R. Ovshinsky Thin-film semiconductor devices
Ford gives Na-S battery details Ford Motor's research division last week disclosed details of the new bat tery concept (C&EN, Sept. 26, page 24) it has developed—a liquid elec trode, sodium-sulfur system which uses a solid electrolyte. But the com pany says it won't have a car-size pro totype battery ready in time to use in the electric vehicles now being built by Ford and its English subsidiary for testing sometime next spring. The English (and subsequent U.S.) tests will begin with conventional lead-acid batteries. Key to the new battery is a ceramic electrolyte, which is about 90% alu minum oxide (β-alumina form). The electrolyte separates the liquid sodium and sulfur electrodes, and behaves as a molecular sieve—porous to sodium ions but impervious to sulfur or the reaction product. During discharge sodium ions migrate through the ce ramic and react with sulfur to form sodium sulfide, completing the internal battery circuit. Ford chemists say the ceramic's conductivity to the so dium ion current compares favorably with sulfuric acid or potassium hy droxide electrolytes used in conven tional batteries. The ceramic elec trolyte can be readily formed and sintered by conventional methods, the company says. Because the electrodes are liquid, Ford scientists explain, there is no mechanism for deterioration of the battery on repeated recycling or on deep discharge, as is the case with solid electrode-liquid electrolyte sys tems. The use of liquid electrolytes also means that the battery operating temperature must be relatively high— 250° to 300° C. But the heat liber ated during discharge is sufficient to maintain these temperatures and the battery may require cooling during operation at peak loads. Futhermore, scaled-up versions can be suitably in sulated to maintain the battery at op erating temperature for up to 14 days of inactivity. Startup from ambient temperatures would require a warmup period. An energy density of about 150 watt-hours per pound is projected for the 'sodium sulfur battery. This is 12 to 15 times that available with leadacid batteries. Alkaline batteries, such as nickel-cadmium, silver-cad mium, and silver-zinc can achieve be tween 16 and 50 watt-hours per pound but are too expensive for vehicle applications. Ford expects to have a 2-kw. ver sion of the battery by the end of next year. Another year beyond that will be required to develop a 40-kw. unit adaptable to vehicular transportation. But by that time another battery
