US 8,552,659 B2Granted

Method and apparatus for discriminating modulated light in a mixed light system

AssigneeKoninklijke Philips N.V.

InventorsIan Ashdown, Marc Salsbury

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Abstract

Methods and apparatus are disclosed for providing optical emission feedback control for an illumination system comprising mixed light including light from a first light source (135) and a second light source (140). Each light source is driven by a drive current configured using a control and/or modification signal associated with that light source. The control signal in turn can be configured using a modification signal associated with the light source. An optical signal indicative of the mixed light is generated, for example using an optical sensor (150), and the optical signal is processed based on a reference signal to provide measurements indicative of light from each light source, which are used for feedback control of the illumination system. The reference signals can be generated locally or based on a corresponding control or modification signal. To provide measurements for a light source, processing (198) of the optical signal can comprise mixing (235) and compensation (255) operations based on control and/or modification signals associated with that light source.

An illumination device for generating light having a desired luminous flux and chromaticity, the illumination device comprising:

(a) one or more first light sources adapted to generate a first light having a first spectral power distribution, and one or more second light sources adapted to generate a second light having a second spectral power distribution different than the first spectral power distribution;
(b) a first current driver operatively coupled to the one or more first light sources, the first current driver configured to selectively supply electrical drive current to the one or more first light sources based on a first control signal, and a second current driver operatively coupled to the one or more second light sources, the second current driver configured to selectively supply electrical drive current to the one or more second light sources based on a second control signal;
(c) an optical sensor for sensing a portion of an output light which includes a combination of the first light and second light, the optical sensor configured to generate an optical signal indicative of radiant flux of the output light;
(d) a processing module operatively coupled with the optical sensor and receiving the optical signal therefrom, the processing module comprising:
(i) a first filtering module including a first mixing module, the first mixing module configured to perform mixing of a first filtered signal indicative of a first portion of the optical signal using a first reference signal, the first filtering module thereby providing a first output signal indicative of a characteristic of a portion of the first light;
(ii) a second filtering module including a second mixing module, the second mixing module configured to perform mixing of a second filtered signal indicative of a second portion of the optical signal using a second reference signal, the second filtering module thereby providing a second output signal indicative of a characteristic of a portion of the second light;
and
(e) a controller operatively coupled with the first current driver, second current driver, and the processing module, the controller being configured to generate the first control signal and second control signal based at least in part on the respective first output signal and the second output signal, said first control signal and second control signal being configured using a first modification signal and second modification signal, respectively, the first modification signal being indicative of time-varying aspects of the drive current for the first light source and/or first control signal, and the second modification signal being indicative of time-varying aspects of the drive current for the second light source and/or second control signal,
wherein the first filtering module further includes a first compensation module configured to provide the first output signal based at least on output of the first mixing module and the first modification signal.

6 more elements

Abstract

Claims20