Neon Lighting - Neon Glow Lamps and Plasma Displays

Neon Glow Lamps and Plasma Displays

In neon glow lamps, the luminous region of the gas is a thin, "negative glow" region immediately adjacent to a negatively charged electrode (or "cathode"); the positively charged electrode ("anode") is quite close to the cathode. These features distinguish glow lamps from the much longer and brighter "positive column" luminous regions in neon tube lighting. The energy dissipation in the lamps when they are glowing is very low (about 0.1 W), hence the distinguishing term cold-cathode lighting.

Some of the applications of neon lamps include:

• Pilot lamps that indicate the presence of electrical power in an appliance or instrument (e.g. an electric coffee pot or power supply).
• Decorative (or "figural") lamps in which the cathode is shaped as a flower, animal, etc.. The figures inside these lamps were typically painted with phosphorescent paints to achieve a variety of colors.
• Active electronic circuits such as electronic oscillators, timers, memory elements, etc..
• Intricate electronic displays such as the Nixie tube (see photograph).

The small size of the negative glow region of a neon lamp, and the flexible electronic properties that were exploited in electronic circuits, led to the adoption of this technology for the earliest plasma panel displays. The first monochrome dot matrix plasma panel displays were developed in 1964 at the University of Illinois for the PLATO educational computing system. They had the characteristic color of the neon lamp; their inventors, Donald L. Bitzer, H. Gene Slottow, and Robert H. Wilson, had achieved a working computer display that remembered its own state, and did not require constant refreshing from the central computer system. The relationship between these early monochrome displays and contemporary, color plasma displays and televisions was described by Larry F. Weber in 2006, "All plasma TVs on the market today have the same features that were demonstrated in the first plasma display which was a device with only a single cell. These features include alternating sustain voltage, dielectric layer, wall charge, and a neon-based gas mixture." As in colored neon lamps, plasma displays use a gas mixture that emits ultraviolet light. Each pixel has a phosphor that emits one of the display's base colors.