SOLID STATE GAUGES NEAR TO PRODUCTION

Press, Volume CXVI, Issue 34147, 7 May 1976, Page 10

SOLID STATE GAUGES NEAR TO PRODUCTION

One problem facing motorists in this country is the conversion of miles to kilometres. Now instruments can be made to show either at the touch of a switch. This is one of the advantages of solid state displays for instrument panels in cars which have reached an advanced state of development, although no mass production car has yet been fitted, British Correspondents report. There are a variety of

types of solid state displays in existence, and under development. The direct current electroluminescence display (D.C.E.1.) is one which is likely to be used in the automotive industry. The D.C.E.L. display is based on laminar glass construction enclosing phosphor patterns. When a direct current is passed through the phosphor, the molecular layer in immediate contact with the conductive pattern on the glass emits- light. Excitation, though by direct current, is normally in the form of pulsed D.C. for longer life and lower power consumption, and consequently less selfheating. The colour of light is a function of the phosphor. The most highly developed phosphor currently in use is zinc sulphide which emits a predominantly yellow light. Development of phosphors emitting different colours is proceeding. Eventually it may be possible for various phosphors to be silk screened on to the glass plate so that the desired colours for the dis-

play can be achieved directly. At present different colours are obtained from the yellow phosphor by using optical filters.