Electron-stimulated luminescence (ESL)
– ESL is the production of light by cathodoluminescence.
– It is achieved by a beam of electrons hitting a fluorescent phosphor surface.
– ESL is used in cathode ray tubes (CRT) and experimental light bulbs.
– Cathodoluminescent light bulbs have a transparent glass envelope coated with a light-emitting phosphor layer.
– ESL lamps do not use mercury and have a longer lifetime compared to incandescent bulbs.
ESL vs. other lighting technologies
– ESL lamps have a color rendering index of 90.
– They consume 70% less energy than standard incandescent bulbs.
– ESL lamps have a claimed lifetime of 10,000 hours, more than ten times that of incandescent bulbs.
– ESL lamps do not have the delay in illumination associated with cathode ray tubes.
– ESL lamps attract less dust compared to CRTs.
History
– In 1958, Ferranti introduced flood beam CRT-type stroboscope lamps.
– Vu1 Corporation released ESL lamp samples in 2011.
– Vu1 Corporation is no longer in operation.
Related concepts
– CRT projector
– Nimo tube
– Electroluminescence
– Electroluminescent display (ELD)
– Fluorescence
References
– Melanson, Donald (17 September 2009). Vu1 Corporation sees bright future for ESL light bulbs.
– Zyga, Lisa (16 September 2009). Company Claims ESLs to be the Future of Light Bulbs (w/ Video).
– Hornyak, Tim (16 September 2009). Are ESL bulbs better than CFL or LED?.
– Nitz, Brian (12 March 2012). Are ESLs A Mercury-Free Replacement for CFL Lights?.
– Vestel, Leora Broydo (9 April 2009). The Promise of a Better Light Bulb?. Source: https://en.wikipedia.org/wiki/Electron-stimulated_luminescence
Electron-stimulated luminescence (ESL) is production of light by cathodoluminescence, i.e. by a beam of electrons made to hit a fluorescent phosphor surface. This is also the method used to produce light in a cathode ray tube (CRT). Experimental light bulbs that were made using this technology do not include magnetic or electrostatic 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-type dimmers to control the light level. Sample produced with lights produced so far have a color rendering index of 90. The energy consumption can be 70% less than that of a standard incandescent light bulb. 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 lamps, 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 all cathode ray tubes – 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.
