Electron stimulated luminescence

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For the phenomenon in materials science, see Cathodoluminescence.
Example ESL-lamp

Electron Stimulated Luminescence (ESL) is light produced by accelerated electrons hitting a phosphor (fluorescent) surface in a process known as cathodoluminescence.[1][2][3][4] This is the process of light generation in a cathode ray tube (CRT) display, but lamps are built without magnetic or electrostatic deflection of the electron beam.[5]

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 five thousand volts to the light emitting device, and the electrons transiting from cathode to anode are essentially unfocused. Additional circuits allow triac-type dimmers to control the light level.[6] Lights produced so far have a color rendering index of 85. The energy consumption can be 70% less than that of an incandescent light bulb, which produces light by heating a thin filament to incandescence. Lifetimes can be as long as 10,000 hours, five times longer than an incandescent light bulb's.[7]

ESL lamps do not use mercury like fluorescent lamps which produce light by electrically exciting mercury vapor, which in turn radiates UV light towards a phosphor layer that converts the light into the visible spectrum.[8] The first commercially available ESL product was a reflector bulb. A standard pear shaped light bulb is planned for 2013, for the European and Middle East markets.

Independent product testing[citation needed] suggests ESL boasts better light quality than both LED and CFL, with full dimmability. Drawbacks include a slightly larger-than-normal base (which favors newer recessed "can" installations) and a slight delay in illumination when switched on, similar to CFLs.[9]

See also[edit]


  • [1] Patent application with description (filed 2008-02-05)