Mobile Handset Design Line has CAP-XX article on LED flash power in camera phones. The proposal is to use 0.55F super-capacitors to provide high current pulse for LED flash. There is a table comparing various light sources in different camera-phones vs. super-capacitor options:
Source | Storage Capacitor | Distance (m) | Peak Light Power (lux) | Exposure Time (msecs) | Light Energy (lux.secs) |
---|---|---|---|---|---|
Xenon, SonyEricsson K750 | 60μF | 1 | 370,000 | <1> | 37.0 |
Xenon, SonyEricsson K800 | 2 x 14μF | 1 | 203,000 | <1> | 16.0 |
Xenon, Gigabyte cell phone | 15μF | 1 | 139,000 | <1> | 6.2 |
4 x LEDs @ 1A each | 0.55F | 1 | 708 | 17 | 10.8 |
33 | 21.9 | ||||
67 | 43.7 | ||||
2 x LEDs @ 1A each | 0.55F | 1 | 349 | 17 | 5.3 |
33 | 10.9 | ||||
67 | 21.4 | ||||
Nokia N73 LED Flash | NA | 1 | 20.0 | 90 | 1.71 |
Xenon, SonyEricsson K750 | 60μF | 2 | 97,000 | <1> | 9.5 |
Xenon, SonyEricsson K800 | 2 x 14μF | 2 | 53,000 | <1> | 4.2 |
Xenon, Gigabyte cell phone | 15μF | 2 | 36,000 | <1> | 1.7 |
4 x LEDs @ 1A each | 0.55F | 2 | 175 | 17 | 2.7 |
33 | 5.4 | ||||
67 | 10.8 | ||||
2 x LEDs @ 1A each | 0.55F | 2 | 86 | 17 | 1.3 |
33 | 2.7 | ||||
67 | 5.3 | ||||
Nokia N73 LED Flash | NA | 2 | 5.0 | 90 | 0.43 |
CAP-XX Flash Power
Reviewed by MCH
on
April 06, 2007
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