Summary: New Techniques in Video Displays
The preceding papers are summarized, with their important points gathered together for convenient reference.
On the use of phosphors excited by low-energy electrons in a gas-discharge flat-panel display
A gas-discharge flat-panel display device has been constructed in which the light output is white and the color is independent of intensity. The device is based on the Burroughs Self-Scan®structure. A white output was obtained by combining the orange glow of a gas mixture which is predominantly neon with the green emission of a ZnO:Zn phosphor (P15) deposited on transparent conducting anodes and excited by incident low-energy electrons. A peak spot intensity of 3000 fL in the white was achieved at a display-cell current density of 0.33 Aċcm-2and 180 V across the display cell. In a control region where no phosphor was deposited and the output was orange, the peak spot brightness was 7500 fL. Experiments on single-cell devices using helium, neon, argon, and xenon are described which demonstrate that the phosphor is indeed excited by low-energy electrons rather than by UV radiation from the gas discharge. The latter method had been used exclusively to date to obtain colors other than orange in gas-discharge flat-panel displays.
Measurement and Demonstration of Thermal Expansion Coefficient
There are many classroom demonstrations, such as the ball-and-ring experiment, for showing the existence of thermal expansion of solids. The coefficient of linear expansion α (= increase in length divided by the original length times the change in temperature) may be measured in high school laboratories using a number of methods.1–4 In this paper we describe an especially simple experiment for determining α for a metal rod. It is based on the well-known optical lever method and is suitable for either a laboratory experiment or a classroom exercise.