Stephen F. Dreyer

Bio: Stephen F. Dreyer is an academic researcher. The author has contributed to research in topics: LED circuit & Light-emitting diode. The author has an hindex of 2, co-authored 2 publications receiving 557 citations.

Apparatus, Method and System for Providing AC Line Power to Lighting Devices

Abstract: An apparatus, method and system are disclosed for providing AC line power to lighting devices such as light emitting diodes (“LEDs”). A representative apparatus comprises: a plurality of LEDs coupled in series to form a plurality of segments of LEDs; first and second current regulators; a current sensor; and a controller to monitor a current level through a series LED current path, and to provide for first or second segments of LEDs to be in or out of the series LED current path at different current levels. A voltage regulator is also utilized to provide a voltage during a zero-crossing interval of the AC voltage. In a representative embodiment, first and second segments of LEDs are both in the series LED current path regulated at a lower current level compared to when only the first segment of LEDs is in the series LED current path.

Apparatus and method for providing AC line power to lighting devices

Abstract: Apparatus and method are disclosed for providing AC line power to lighting devices such as light emitting diodes (“LEDs”). A representative apparatus comprises: a plurality of LEDs couplable to form a plurality of segments of LEDs; a current sensor; and a controller to monitor a current level through an overall series LED current path, and to provide for first or second segments of LEDs to be in or out of the overall series LED current path at different current levels. The controller is configured to, in a first light emitting diode configuration, cause first and second segments of LEDs to be parallel to one another and in the overall series LED current path. The controller is further configured to, in a second light emitting diode configuration, cause first and second segments of light emitting diodes to be coupled in series and in the overall series light emitting diode current path.

Method for distributed power harvesting using DC power sources

Abstract: A system and method for combining power from DC power sources. Each power source is coupled to a converter. Each converter converts input power to output power by monitoring and maintaining the input power at a maximum power point. Substantially all input power is converted to the output power, and the controlling is performed by allowing output voltage of the converter to vary. The converters are coupled in series. An inverter is connected in parallel with the series connection of the converters and inverts a DC input to the inverter from the converters into an AC output. The inverter maintains the voltage at the inverter input at a desirable voltage by varying the amount of the series current drawn from the converters. The series current and the output power of the converters, determine the output voltage at each converter.

Light Emitting Device

Abstract: By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.

AC driven solid state lighting apparatus with LED string including switched segments

Abstract: A diode selection circuit for a light emitting apparatus according to some embodiments includes a plurality of light emitting devices coupled in series. The diode selection circuit includes a comparator configured to receive a rectified AC input signal and a reference voltage and to generate a control signal in response to comparison of the rectified AC input signal with the reference voltage, a voltage controlled current source configured to supply a current to the plurality of light emitting diodes that is proportional to the rectified AC input signal, and a switch configured to receive the control signal and to shunt current away from at least one of the plurality of light emitting devices in response to the control signal.

COPACKING CONFIGURATIONS FOR NONPOLAR GaN AND/OR SEMIPOLAR GaN LEDs

Abstract: A packaged light emitting device. The device has a substrate member comprising a surface region. The device has a substrate member comprising a surface region. The device also has two or more light emitting diode devices overlying the surface region according to a specific embodiment. At least a first of the light emitting diode device is fabricated on a semipolar GaN containing substrate and at least a second of the light emitting diode devices is fabricated on a nonpolar GaN containing substrate. In a preferred embodiment, the two or more light emitting diode devices emits substantially polarized emission. Of course, there can be other variations, modifications, and alternatives.

Safety mechanisms, wake up and shutdown methods in distributed power installations

Abstract: A distributed power system including multiple DC power sources and multiple power modules. The power modules include inputs coupled respectively to the DC power sources and outputs coupled in series to form a serial string. An inverter is coupled to the serial string. The inverter converts power input from the serial string to output power. A signaling mechanism between the inverter and the power module is adapted for controlling operation of the power modules.