Abstract: An electrical circuit is described that comprises a first string and second LED string coupled in parallel, a first and second transistor, at least one bypass transistor, and a controller. The first transistor is coupled to the first LED string at a first terminal of the first transistor. The second LED string includes multiple LED color strings coupled in series. The second transistor is coupled to the second LED string at a first terminal of the second transistor. The bypass transistor is coupled to one of the color strings. A first terminal of the bypass transistor is coupled to a first terminal of the color string. The second terminal of the bypass transistor is coupled to a second terminal of the color string. The controller controls a gate voltage of the first and second transistors and the bypass transistor to operate all transistors in linear modes.

Abstract: The tunable color mixing system includes a mixing barrel that captures light from multiple light emitting diodes emitting at different colors, mixes the light, and outputs the light with a narrow beam angle from a small area. The array of LEDs in the system is thermally coupled to a heat conductor via thermal pads. A flexible printed circuit is electrically connected to the LEDs to supply and fine-tune the electrical power. The array includes LEDs of at least three emitting colors to achieve an output light having a high color rendering index, tunable to a wide range of correlated color temperatures.

Abstract: A lighting and control system is described. One embodiment of the lighting and control system includes a lighting node and a controller. The lighting node may include a light emitting diode configured for illumination and further configured for optical communication with the controller, a node radio device configured for radio communication with the controller, and a node memory configured to store a node identifier and a group identifier. The controller may include an optical sensor configured to sense illumination of the lighting node and further configured for optical communication with the lighting node, a controller radio device configured for radio communication with the lighting node, and a controller memory configured to store a group identifier. The lighting node and the controller may each further include a power supply and a processor. In one embodiment, the lighting node and the controller belong to a wireless mesh network.

Abstract: A phase change material (PCM) is used as thermal storage for lighting systems. The PCM is placed in a thermally conductive container in close contact with the lighting system. As the PCM absorbs heat, it changes from a solid to a liquid state, but the temperature of the PCM is clamped at its melting point temperature. For LED-based systems, the PCM is selected to have a melting point such that the junction temperatures of the LEDs in the system are maintained at approximately their optimum operating temperature inside the lighting system housing. Because the thermal conductivity of the molten PCM is poor, a low thermal resistance heat flow path is provided from the PCM to the container.

Abstract: A method for communication between a lighting node and a controller is described. One embodiment of the method includes transmitting a command from the controller based on a target illumination profile stored on the controller to the lighting node utilizing a controller radio device and receiving the command from the controller at the lighting node utilizing a node radio device. The method may also include generating illumination having a spectral content from the lighting node utilizing at least a light emitting diode; and receiving the spectral content from the lighting node at the controller utilizing an optical sensor.

Abstract: A lighting node is described. One embodiment of the lighting node includes a lamp, a radio device, and a memory. The lamp is configured for generating illumination. The radio device is configured for radio communication. The radio device is configured to remotely receive a color profile from the controller. The lamp is also configured to generate illumination to substantially match the received color profile. The memory is configured to store a group identifier for the lighting node.

Abstract: A lighting system is described. The lighting system includes a lamp and a first container including a first phase change material thermally connected to the lamp. Heat generated by the lamp during operation is conducted to the first phase change material. The system also includes a second container including a second phase change material thermally connected to the lamp. Heat generated by the lamp during operation is also conducted to the second phase change material, and the second phase change material has a transition point temperature lower than the transition point temperature of the first phase change material of the first container to account for a temperature drop between the second container and the first container. The lighting system also includes a temperature sensor for reducing lamp power if the lamp becomes too hot, and a mounting bracket which may also conduct heat away from the lamp.

Abstract: An optical lens and method for designing the lens are disclosed. The lens includes a first surface and a second surface. Light emitted from multiple light emitting elements enters the lens through a central section of the first surface. The light can be reflected from a reflective central section of the second surface and/or undergo total internal reflection at an outer ring section of the second surface one or more times before exiting the lens through the outer ring section of the second surface. Upon exiting the lens, the light beam has a predetermined divergence angle and has a fairly uniform color in the far field even if the multiple light emitting elements have different peak wavelengths.

Abstract: A lighting system is described. The lighting system includes a lamp and a first container including a first phase change material thermally connected to the lamp. Heat generated by the lamp during operation is conducted to the first phase change material. The system also includes a second container including a second phase change material thermally connected to the lamp. Heat generated by the lamp during operation is also conducted to the second phase change material, and the second phase change material has a transition point temperature lower than the transition point temperature of the first phase change material of the first container to account for a temperature drop between the second container and the first container. The lighting system also includes a temperature sensor for reducing lamp power if the lamp becomes too hot, and a mounting bracket which may also conduct heat away from the lamp.

Abstract: A heat removal assembly for a light emitting diode lighting apparatus is described. One embodiment of the heat removal assembly includes a plurality of fins configured to receive heat from a light emitting diode. In the plurality of fins, two adjacent fins are separated by a gap width, and each fin has a fin length. The heat removal assembly also includes a duct configured to draw a stack-effect airflow through the plurality of fins to remove heat from the plurality of fins. The gap width separating two adjacent fins and the fin length of each of the fins are configured to prevent boundary layer choking the plurality of fins. In one embodiment, the heat removal assembly also includes a conductor and a thermal storage system configured to receive heat from the light emitting diode. A lighting apparatus including the heat removal assembly, a light emitting diode, and a connector plug is also described.

Abstract: An electrical circuit is disclosed for driving color strings that have at least one lamp, preferably a light emitting diode (LED). The color strings can be different lengths. In some embodiments, a switch is coupled in parallel to one of the LED strings to shunt power away from the LED string to a power supply or to one or more other LED strings. In some embodiments, a current injector is configured to remove current from or inject current into a node adjacent to an LED string. Methods are disclosed for producing a desired light output utilizing color strings that may be of dissimilar length and that may contain light emitting diodes of different colors.

Abstract: A phase change material (PCM) is used as thermal storage for lighting systems. The PCM is placed in a thermally conductive container in close contact with the lighting system. As the PCM absorbs heat, it changes from a solid to a liquid state, but the temperature of the PCM is clamped at its melting point temperature. For LED-based systems, the PCM is selected to have a melting point such that the junction temperatures of the LEDs in the system are maintained at approximately their optimum operating temperature inside the lighting system housing. Because the thermal conductivity of the molten PCM is poor, a low thermal resistance heat flow path is provided from the PCM to the container.

Abstract: A heat removal assembly for a light emitting diode lighting apparatus is described. One embodiment of the heat removal assembly includes a plurality of fins configured to receive heat from a light emitting diode. In the plurality of fins, two adjacent fins are separated by a gap width, and each fin has a fin length. The heat removal assembly also includes a duct configured to draw a stack-effect airflow through the plurality of fins to remove heat from the plurality of fins. The gap width separating two adjacent fins and the fin length of each of the fins are configured to prevent boundary layer choking the plurality of fins. In one embodiment, the heat removal assembly also includes a conductor and a thermal storage system configured to receive heat from the light emitting diode. A lighting apparatus including the heat removal assembly, a light emitting diode, and a connector plug is also described.