Electron-stimulated luminescence (ESL) is production of

light Light, visible light, or visible radiation is electromagnetic radiation that can be visual perception, perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400– ...

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 i ...

, i.e. by a beam of

electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

s made to hit a

fluorescent Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...

phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or ...

surface. This is also the method used to produce light in a

cathode ray tube A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen. The images may represent electrical waveforms on an oscilloscope, a ...

(CRT). Experimental

light bulbs Electric light is an artificial light source powered by electricity. Electric Light may also refer to: * Light fixture, a decorative enclosure for an electric light source * ''Electric Light'' (album), a 2018 album by James Bay * Electric Light ( ...

that were made using this technology do not include

magnetic Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, m ...

electrostatic Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word (), mean ...

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 genericized trad ...

-type

dimmer A dimmer is a device connected to a light fixture and used to lower the brightness of the Lighting, light. By changing the voltage waveform applied to the lamp, it is possible to lower the Luminous intensity, intensity of the light output. Al ...

s to control the light level. Sample produced with 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. ''Color rendering'', as defined by the Internat ...

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

incandescent light bulb An incandescent light bulb, also known as an incandescent lamp or incandescent light globe, is an electric light that produces illumination by Joule heating a #Filament, filament until it incandescence, glows. The filament is enclosed in a ...

. 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, to produce ultraviolet and make a phosphor ...

s, which produce light through the electrical excitation of

mercury vapor A mercury-vapor lamp is a gas-discharge lamp that uses an electric arc through vaporized mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger soda lime or borosilicate glass ...

, 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 all

cathode ray tubes A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead-acid battery. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. Conventional current ...

– 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 International PLC or simply Ferranti was a UK-based electrical engineering and equipment firm that operated for over a century, from 1885 until its bankruptcy in 1993. At its peak, Ferranti was a significant player in power grid system ...

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