Abstract: A technique for controlling a Light Emitting Diode (LED) based light system involves driving individual light sources that make up the LED-based light system at non-overlapping intervals so that light source-specific feedback signals can be generated in response to the emitted light. The light source-specific feedback signals are then used to individually adjust the light sources to achieve desired luminance and chrominance characteristics of the emitted light.

Abstract: An apparatus and method thereof for regulating a light source are described. The apparatus includes a light-to-frequency converter that converts light received from the light source into a signal having a corresponding frequency. A circuit coupled to the light-to-frequency converter uses the frequency to regulate light that is emitted from the light source.

Abstract: A system and method for generating white light involves using a combination of phosphor-converted white LEDs and non-phosphor-converted color LEDs to produce white light and adjusting the emitted light in response to feedback signals. Generating white light using a combination of phosphor-converted white LEDs and non-phosphor-converted color LEDs produces white light with an improved CRI and a wide SPD. Adjusting the emitted light in response to feedback allows luminance and chrominance characteristics of the white light to be controlled as the performance of the LEDs changes over time. The emitted light can be adjusted on a per-color basis and/or on a per-group basis, where a group of LEDs includes a combination of at least one phosphor-converted white LED and at least one non-phosphor-converted color LED.

Abstract: 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.

Abstract: A system and method for emitting and detecting light uses a light emitting device, e.g., a light emitting diode, to emit light and to detect incident light. As an example, the system and method may be used in a digital camera, a camera phone or an illuminated device, such as a liquid crystal display device.

Abstract: A light source and method for controlling the same. The light source utilizes a light generator that generates a light signal of a wavelength at an intensity that is set by a control signal. The control signal is controlled by a servo that monitors the light output of the light generator and compares the monitored value with a target value. When the target value is changed, the control signal is initially replaced by a predicted control signal based on the new target value rather than the error signal generated in the servo. This provides time for the servo to adjust to the new target value. In one embodiment, the control signal includes a periodic signal that switches between a value that causes the light generator to generate light of the wavelength and a second value at which the light generator does not generate light of the wavelength.

Abstract: A system and method for generating white light involves using a combination of white, red, green, and blue LEDs to produce white light and adjusting the emitted light in response to feedback signals. A light system has a light source that includes at least one white LED and multiple color LEDs and a spectral feedback control system configured to detect light that is output from the light source and to adjust the light that is output from the light source in response to the light detection. The spectral feedback control system may include a color sensor configured to provide color-specific feedback signals, a controller configured to generate color-specific control signals in response to the color-specific feedback signals, and a driver configured to generate color-specific drive signals in response to the color-specific control signals.

Abstract: The present invention includes a light source having N light generators, a receiver, and an interface circuit. Each light generator emitting light of a different wavelength, the intensity of light generated by the kth generator is determined by a signal Ik coupled to that light generator. The receiver receives a color coordinate that includes N color components, Ck, for k=1 to N, wherein N is greater than 1. The interface circuit generates the Ik for k=1 to N from the received color components and a plurality of calibration parameters. The calibration parameters depend on manufacturing variations in the light generators. The calibration parameters have values chosen such that a light signal generated by combining the light emitted from each of the light generators is less dependent on the manufacturing variations in the light generators than a light signal generated when Ik is proportional to Ck for k=1 to N.

Abstract: A system and method for canceling dark photocurrent in a color sensor circuit is disclosed. A color sensor is described including a color sensor circuit, a dark color sensor circuit, and a differential amplifier circuit. The color sensor circuit receives photocurrent from a color component of a light input. The color sensor circuit outputs a first voltage indicating intensity of the color component. The dark color sensor circuit receives dark photocurrent and outputs a second voltage indicating an offset voltage. The differential amplifier circuit is coupled to the color sensor circuit and to the dark color sensor circuit. The differential amplifier circuit receives the first and second voltages and outputs a final output that cancels contributions of the offset voltage in the first voltage due to the dark photo current.