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Fluorescent amalgam lamp with the option to pre-heat the amalgam to improve run-up Disclosure Number: IPCOM000130616D
Publication Date: 2005-Oct-31
Document File: 3 page(s) / 185K

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Fluorescent amalgam lamp with the option to pre-heat the amalgam to improve run-up

Hot Cathode Fluorescent Lamps (HCFL) are used as light sources in LCD backlights. The advantage of these lamps over the commonly for backlighting used Cold Cathode Fluorescent Lamps (CCFL) is that the light output per lamp is much higher. This surplus of light is traded in for picture quality improvements. Motion blur reduction, higher contrast (dynamic contrast) and larger viewing angle are achieved by introducing the so called "scanning operation" of the lamps in the Backlight unit.

Reduction of power consumption in backlighting systems is important. One of the possible solutions to reduce the power is by applying amalgam lamps in stead of the nowadays used pure mercury lamps. The reason for this is that the HCFL lamps as used today are operated "over the lumen top". The temperature of the coldest spot (measured on the lamp inside a operating backlight unit) is higher than the optimum temperature (and therefore the mercury pressure in the lamp is higher than the optimum mercury pressure). Using amalgams, the lumen output becomes less temperature dependent and the amalgam can be designed in such a way that the optimum mercury pressure is reached at the temperature as found in the Backlight unit.

TL-like amalgam lamps show a low initial light output. This because the mercury vapour pressure above such an amalgam at ambient temperature is much lower than the mercury vapour pressure above a liquid mercury pool (as in an ordinary pure Mercury fluorescent lamp). Also the run-up behaviour of such an amalgam lamp is worse compared to the pure mercury fluorescent lamp. When the amalga...