MOVING LIGHTED IMAGE
CD 1967021 E&MP46.002
March 20, 1961
An electronic panel less than one-half inch thick that utilizes a new principle to produce a moving, lighted image was described here today by a scientist of General Telephone & Electronics Laboratories Incorporated at the international meeting of the Institute of Radio Engineers.
Commenting on potential uses of the new device, Dr. Herbert Trotter, Jr., President of the research subsidiary of General Telephone & Electronics Corporation, said, “It would be premature to speculate at this time on specific future applications. A great deal of research and engineering work remains to be done before the new development can be applied commercially.”
One of the major advantages of the device, according to Dr. Trotter, is its ability to display an image on a thin, flat panel. Conventional electronic display devices use a cathode ray tube to produce an image.
Yando Describes His Invention
The inventor of the device, Stephen Yando of GT&E Laboratories at Bayside, New York, described the new development as “an entirely new combination of electrical phenomena that have been in general use for a number of years -- piezoelectricity and electroluminescence.”
Piezoelectricity is the phenomenon exhibited by certain materials that expand in one direction and contract along other directions when an electric field is applied. Conversely, when mechanical stresses are applied to a flat plate of piezoelectrical material, electric charges are developed on the face of the plate.
Electroluminescence involves the excitation of a phosphor coating on a thin, flat panel through the application of an electric field, thus causing the phosphor coating to give off light.
The device described today consists of a thin, flat panel composed of a “piezoelectric” ceramic material, one surface of which is coated with a layer of electroluminescent material. When voltage signals are applied to several electrodes on the edges of the flat piezoelectric panel, traveling acoustical waves are introduced into the ceramic material. Electric fields which accompany these acoustical waves interact with the electroluminescent layer to produce a “spot” of illumination on the panel. The position of the “spot” is controlled by varying the relative timing of the electrical pulses to produce an electronic wave pattern. The light intensity of the “spot” is modulated by an electric field applied to a transparent conductive layer covering the electroluminescent layer.
As suitably timed input signals are applied, a series of light spots or lines are produced which can form an image. By varying the timing of the signals, the image can be made to move about the panel. In certain applications, only a dot of light will be required. Nonlinear resistance material can be included in the panel to eliminate background light, leaving only the desired display.
Early Potential In Military, Laboratory Field
In its present stage, the device, according to Dr. Trotter, appears to have its earliest potential uses in military and laboratory devices where the production of illuminated lines and dots is needed in electronic systems and equipment.
“This new development is a major outgrowth of the Laboratories’ work in electroluminescence, which is the first new light source in 50 years,” Dr. Trotter said. He pointed out that Sylvania Electric Products Inc., a GT& E subsidiary, announced the first commercial application of electroluminescence ten years ago with the introduction of “Panelescent” lighting, a flat panel of light used for many types of illumination.
Original Caption by Science Service
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