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Stand-by mode for Dynamic Light Sources Disclosure Number: IPCOM000099799D
Publication Date: 2005-Mar-15
Document File: 1 page(s) / 4K

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The Prior Art Database



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Stand-by mode for Dynamic Light Sources

At the moment LCD backlights are provided with Dynamic Light Sources (DLS) using pure mercury to generate light. The light output is maximal if the coldest spot in the lamp has a temperature that prescribes the optimal mercury vapour pressure.

Because of high temperatures in the backlight unit, the mercury vapour pressure increases beyond the optimal pressure and consequently the light output is lowered in the order of 10 - 20%.

Using a suitable amalgam overcomes this problem by establishing an optimal mercury vapour pressure over a broader temperature range. A drawback of using only a main amalgam is the slow run up of the lamp.

To avoid this, it is proposed to provide these lamps with a STANDBY MODE when the backlight unit is in OFF periods. This means that the main amalgam then has to be heated up to moderate temperatures of e.g. 40 °C during the off time in case BiIn amalgam is used. The heating has to be done in such a way that no mercury will be distilled to the cold spot of the lamp.

The advantage of this standby mode is that the mercury vapour pressure at the start up of the lamp is already boosted to a vapour pressure equal to pure mercury at room temperatures. This results in a higher initial light output and a faster run up.

Because the amalgam has to be heated in the standby mode only with a deltaT of ~10 - 20 °C, the extra power consumption in the standby mode is limited to a minimum when the heating power is e...