A system of at least three multi-colored LED's has an optimized color rendering index by proper selection of the wavelengths of each LED, such system being useful for general illumination purposes.
A lighting system includes at least two light-emitting diodes each emitting, in operation, visible light in a preselected wavelength range. A converter converts part of the visible light emitted by one of the diodes into visible light in a further wavelength range so as to optimize the color rendition of the lighting system. The diodes include a blue light-emitting diode and a red light-emitting diode. Further, the converter includes a luminescent material for converting a portion of the light emitted by the blue light-emitting diode into green light.
A light source that generates light that is perceived to have a predetermined color is disclosed. The light source includes first and second red LEDs and a non-red light emitter. The first and second red LEDs emit light in the red portion of the spectrum but at different wavelengths. The non-red light emitter emits light at a wavelength in a non-red portion of the spectrum. A controller varies the intensity of the first and second red LEDs to provide a combined light signal that is perceived as having the predetermined color. In one embodiment, the non-red light emitter includes a fluorescent light, and the controller adjusts the intensities of the red LEDs to provide a source that is perceived as an incandescent source of a predetermined color temperature.
As a white light source, the lighting system (1) has at least three light-emitting diodes (6, 7, 8) for providing visible light at preselected wavelengths. The invention is characterized in that the lighting system (1) is provided with at least one fourth light-emitting diode (9) which, in operation, emits visible light in a further wavelength region, the maximum of the spectral emission of the fourth light-emitting diode (9) lying in the further wavelength region from 575 to 605 nm. Preferably, the further wavelength region ranges from 585 to 600 nm. Preferably, the color rendition of the lighting system (1) is above 60. Preferably, the luminous efficacy of the lighting system (1) is above 30 lm/W, preferably above 40 lm/W. In another preferred embodiment, the color temperature of the lighting system (1) can be adjusted by selectively switching the light-emitting diodes (6, 7, 8, 9).
LED module for generating white light having a plurality of white-light LEDs including at least one LED with a central wavelength of between 495 nm and 507 nm, at least one LED with a central wavelength of between 511 nm and 529 nm, at least one LED with a central wavelength of between 586 nm and 602 nm, and at least one LED with a central wavelength of between 618 nm and 630 nm.
The present invention describes a method and luminaire for driving an array of LEDs with at least one LED in each of a plurality of colors in a luminaire. This method controls the light output and color of the LEDs by measuring color coordinates for each LED light source for different temperatures, storing the expressions of the color coordinates as a function of the temperatures, deriving equations for the color coordinates as a function of temperature, calculating the color coordinates and lumen output fractions on-line, and controlling the light output and color of said LEDs based upon the calculated color coordinates and lumen output fractions.
