Richard K. Williams,Keng Hung Lin,Daniel Schell,Joseph P. Leahy
申请号：
US16446862
公开号：
US20190373687A1
申请日:
2019.06.20
申请国别(地区):
US
年份:
2019
代理人:
摘要：
The LEDs in a phototherapy LED pad are controlled so that the intensity of the light varies in accordance with a sinusoidal function, thereby eliminating the harmonics that are generated when the LEDs are pulsed digitally. This is accomplished analogically by using a sinusoidal wave to control the gate of a MOSFET connected in series with the LEDs or by using a digital-to-analog converter to control the gate of the MOSFET with a stair step function representative of the values of a sinusoidal function at predetermined intervals. Alternatively, pulse-width modulation is used to control the gate of the MOSFET in such a way that the average current through the LEDs simulates a sinusoidal function. In additional to using a simple sine wave function, the LED current may also be controlled in accordance with “chords” containing multiple sine waves of different frequencies.
