Phototherapy system with dynamic drive for light-emitting diodes
US11109458B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 2019 |
| Grant date | Aug 31, 2021 |
| Priority date | — |
| Expiry date | Jun 20, 2039 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B45/397
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.