Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Reexamination Certificate
2007-12-27
2009-12-29
Epps, Georgia Y (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
C250S2140LS, C315S307000, C362S231000
Reexamination Certificate
active
07638744
ABSTRACT:
The system for stabilizing wavelength of LED (light emitting diode) radiation in backlight module of the LCD (liquid crystal display) comprises two photodiodes, a plurality of LEDs, a microprocessor unit (MCU) and a driver circuit, wherein two photodiodes have different photo sensitivities in response different wavelengths. A target value, associated with a ration of photo sensitivities of the two photodiodes under two different wavelength radiations, is stored to the MCU as a referred value. Thus, another wavelength (or wavelength variation) of LED radiation is derived by comparing another target value with the referred value. The MCU determines a correction constant based on a color match function of the derived wavelength, and outputs a compensation signal to compensate LED, wherein the compensation signal is equal to multiplication of the correction constant and an original light intensity compensation signal for compensating light intensity loss of the LED.
REFERENCES:
patent: 6507159 (2003-01-01), Muthu
patent: 6678293 (2004-01-01), Colace et al.
patent: 7133136 (2006-11-01), Soskind
patent: 7220959 (2007-05-01), Nishimura
Cao Hong-Xi
Chang Kun-Chieh
Ho Fu-Shun
Huang Zhi-Xian
Yang Chun-Chieh
Epps Georgia Y
Industrial Technology Research Institute
J.C. Patents
Williams Don
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