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.
Abstract:
The present invention provides a system and method for controlling one or more light-emitting elements which are driven by forward currents to generate mixed light for use, for example, through a luminaire. The system has one or more light sensors for acquiring feedback optical sensor data and a user interface for providing reference data representative of a desired mixed light. The system also has a controller for transforming either the sensor data or the reference data into the coordinate space of the other and to determine a difference between the sensor and the reference data in that coordinate space. The controller is configured to adjust the forward currents during operating conditions so that the sensor data matches the setpoint data. The present invention also provides a system and method that can at least partially compensate certain temperature induced effects when transforming the optical sensor or the reference data.
Abstract:
Tristimulus colorimeter apparatus and methods of tristimulus colorimetry are described. The tristimulus colorimeter apparatus can be used for determining color of light by specifying a first, a second and a third tristimulus value for the light. The colorimeter apparatus may detect signals according to color matching functions having spectral responsivities matched by detectors of the colorimeters. The detected signals may be processed by one or more computations, such as matrix operations, to provide the tristimulus values of the color.
Abstract:
The present invention provides a light source having an improved output optical quality. In general, the light source comprises one or more light-emitting elements in each of at least a first, a second and a third colour. The combined spectral power distribution of these light-emitting elements generally defines a spectral concavity. The light source further comprises a light-excitable medium configured and disposed to absorb a portion of the light emitted by one or more of the light-emitting elements and emit light defined by a complementary spectral power distribution having a peak located within the concavity. By combining the spectral output of the light-emitting elements with the spectral output of the light-excitable medium, an optical quality of the light source is improved.
Abstract:
The present invention provides a method and apparatus for controlling the thermal gradient and therefore the thermal stress in light-emitting elements in which the light-emitting elements are exposed to temperature gradients caused by varying drive current under operating conditions. The method and apparatus according to the present invention can reduce the thermal stress in a light-emitting element by adaptively determining a drive current transient for a required change in the drive current from a first drive current state to a desired second drive current state, wherein the drive current transient is adaptively determined in order to substantially minimize the change in applied voltage over time, during the transition time period.
Abstract:
The present invention provides a light source, method, computer-readable storage medium and computer program product for optimising one or more illumination characteristic thereof. In particular, the present invention provides a light source comprising four or more light-emitting elements, or groups or arrays thereof, each one of which having a respective predefined emission spectrum which, when combined in accordance with a given intensity ratio, provide illumination at a particular colour temperature. This light source may comprise an internal and/or external selection module for selecting one or more illumination characteristics to be optimised, and internal and/or external computing module for optimising drive parameters of the light source to provide the optimised illumination characteristic selected. The light source may optionally be hardwired to operate according to predefined drive parameters selected, using a method, computer-readable storage medium and/or computer program product of the present invention, in order to optimise a pre-selected illumination characteristic.
Abstract:
Disclosed are a method and apparatus for optical feedback control for a lighting unit (10) for generating light having a desired luminous flux and chromaticity. The control signals (110, 210) for the drive currents of each array of one or more light sources are independently configured using a suitable modification signal (111, 211) for each array. In this manner, upon detection of the output light of the arrays, which will have encoded therein a respective modification signal, a controller can be configured to separate each array's contribution based on the respective modification signal. The modification signal can be configured to modulate the pulse widths of drive currents supplied to each array.
Abstract:
A light-emitting element control system is described comprising a series connection of one or more LEE units, each comprising one or more LEEs and a unit activation module. The unit activation module associated with a LEE unit is configured to controllably activate, in response to a unit activation control signal, the one or more LEEs in that unit. A control module is operatively coupled to each of the unit activation modules and configured to provide the unit activation control signals thereto. A converting module is operatively coupled to the series connection of LEE units, adapted for connection to a source of power and configured to provide a drive current to the LEE units.
Abstract:
The present invention provides a ripple compensation method and apparatus that provides a means to compensate for drive current ripple-induced brightness fluctuations in an LEE based illumination system. The ripple compensation apparatus comprises a ripple evaluation module which is configured to evaluate a ripple compensation factor based on an evaluated fluctuation of the drive current. The evaluation of the fluctuation of the drive current can be determined based on information collected during operation of the LEE based illumination system and/or based on predetermined operational characteristics of the LEE based illumination. A control system comprises the ripple evaluation module and is operatively coupled to the one or more light-emitting elements, wherein the control system is configured to determine and provide control signals for operation of the one or more light-emitting elements based on the ripple compensation factor.
Abstract:
The invention provides a lighting device package with one or more light-emitting elements operatively coupled to a substrate; a compound lens disposed to interact with light emitted by the one or more light-emitting elements, the compound lens including at least an inner lens element and an outer lens element, the inner lens element having a first index of refraction and the outer lens element having a second index of refraction, the first index of refraction being greater than the second index of refraction; the compound lens, the one or more light-emitting elements and the substrate defining an enclosed space between them; and an encapsulation material filling at least part of said space, the encapsulation material having a third index of refraction equal or greater than the first index of refraction.