Method of determining PWM values for LED modules
US9097744B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 25, 2012 |
| Grant date | Aug 4, 2015 |
| Priority date | — |
| Expiry date | Nov 15, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B45/24
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for obtaining PWM values for an LED module having n LED chips from various color ranges, wherein n>1, wherein for each LED chip a PWM value for producing a target color value is obtained, is characterized in that a calibration measurement is performed in which the wave lengths (λcal1, λcal2, λcal3) and/or the standard color proportion values ((x,y)cal1, (x,y)cal2, (x,y)cal3) and possibly the luminous flux values of the individual LED chips are determined at a calibration temperature (Tcal), PWM control points are obtained, where each PWM control point contains a PWM value for each of the n color ranges of the LED module, during operation of the LED module a value that depends on the present temperature (Ta) of the LED module, in particular the present temperature (Ta) itself, is determined, and a first and a second PWM control point are assigned to this temperature-dependent value, and the PWM values for producing the target color value are obtained through interpolation between the assigned PWM control points. This makes it possible to realize a precise color mixture in the LED module in a cost-effective way, with little computing power, despite temperature fluctuations (…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.