PWM illumination control circuit with low visual noise for...

Details PWM illumination control circuit with low visual noise for... PWM illumination control circuit with low visual noise for...

2007-02-27

2007-02-27

Vo, Tuyet Thi (Department: 2821)

Electric lamp and discharge devices: systems

Pulsating or a.c. supply

With power factor control device

C315S246000, C315S2090SC, C315S224000, C315S291000

Reexamination Certificate

active

10708212

ABSTRACT:
A pulse width modulation (PWM) illumination control circuit with a low visual noise for driving a light-emitting diode (LED) is provided. An illumination control pulse-generating unit is used to generate an illumination control pulse signal according to an illumination-adjusting signal. A duty cycle, a phase shift or a frequency of the illumination control pulse signal varies with time within a predetermined scope for controlling a DC/DC converter to drive the light-emitting diode so that the overall visual noise level of the PWM illumination control circuit is improved.

REFERENCES:
patent: 6057651 (2000-05-01), Usami
patent: 6304464 (2001-10-01), Jacobs et al.
patent: 6586890 (2003-07-01), Min et al.
patent: 2003/0030385 (2003-02-01), Toyama
patent: 2003/0085749 (2003-05-01), Xu et al.
patent: 2003/0151601 (2003-08-01), Chung et al.
patent: 306417 (2001-11-01), None

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