Electron-stimulated luminescence (ESL) is production of

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...

cathodoluminescence Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum. A familiar example is ...

, i.e. by a beam of

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no ...

s made to hit a

fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...

phosphor surface. This is also the method used to produce light in a cathode ray tube (CRT). Experimental

light bulbs An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the soc ...

that were made using this technology do not include magnetic or

electrostatic Electrostatics is a branch of physics that studies electric charges at rest ( static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amb ...

means to deflect the electron beam. A cathodoluminescent light has a transparent glass envelope coated on the inside with a light-emitting phosphor layer. Electrons emitted from a cathode strike the phosphor; the current returns through a transparent conductive coating on the envelope. The phosphor layer emits light through the transparent face of the envelope. The system has a power supply providing at least 5kVDC to the light emitting device, and the electrons transiting from cathode to anode are essentially unfocused. Additional circuits allow

TRIAC A TRIAC (triode for alternating current; also bidirectional triode thyristor or bilateral triode thyristor) is a three terminal electronic component that conducts current in either direction when triggered. The term TRIAC is a genericised trade ...

-type dimmers to control the light level. Lights produced so far have a

color rendering index A color rendering index (CRI) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with a natural or standard light source. Light sources with a high CRI are desirable in ...

of 90. The energy consumption can be 70% less than that of a standard

incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxid ...

. Claimed lifetime can be as long as 10,000 hours which is more than ten times that of a standard incandescent light bulb. Unlike

fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...

s, which produce light through the electrical excitation of mercury vapor, ESL lamps do not use mercury. The first commercially available ESL product was a reflector bulb. Drawbacks include high weight, a slightly larger-than-normal base and – as with compact fluorescent lamps – when switched on, a slight delay before illumination begins and a static charge which attracts dust to the bulb face. As of 2016 the cost is higher and claimed efficiency is less than half that of commercially available LED bulbs, although it is considerably better than that of traditional incandescent lamps.

History

In 1958,

Ferranti Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. The company was once a constituent of the FTSE 100 Index. The firm was known ...

introduced a line of flood beam CRT-type stroboscope lamps. Following delays, one company, called Vu1 Corporation, released ESL lamp samples in 2011. The company has not continued in operation.

References

External links

Patent application with description (filed 2008-02-05)

Cathodoluminescent lamps: A clean and energy-efficient complement to LEDs

Prototype of cathodoluminescent lamp for general lighting using carbon fiber field emission cathode

Cathodoluminescent UV Sources for Biomedical Applications
{{Artificial light sources Types of lamp Glass applications Energy-saving lighting Vacuum tubes

History

See also

References

External links