Osram Sylvania Inc.

Benjamin Alexandrovich

Valery A Godyak

Robert B Piejak

Bernhard Siessegger

Alexander A Sapozhnikov

James N Lester

Charles A Brunault

Robert Martin

David Betts

Kenneth R Hutcherson

Eugene Statnic

Techniques are disclosed for dimming LED strings using frequency modulation (FM) dimming and burst control dimming. At high brightness levels, FM dimming may be used to decrease the current through LED strings by increasing the switching frequency of pulses within a pulse train of an AC current source. At low brightness levels, or after the switching frequency has been increased to the resonant frequency of the current source, burst control dimming may decrease the current through LED strings by decreasing the duty cycle of the pulse train of the current source. At high brightness levels, FM dimming and burst control dimming may be combined by decreasing the duty cycle of the pulse train at each of a number of increasing switching frequency values. FM dimming may also be combined with frequency hopping in order to increase the number of available frequency steps.

Hybrid dimming control techniques for LED drivers

Techniques are disclosed for independent control of individual LED strings driven from a single AC current source. A lighting driver circuit includes a DC-AC inverter with series resonance that provides a current that may be split into multiple currents for driving multiple LED assemblies. Current splitting transformers may be used to divide the current from the AC source, and the amplitude of the current from the AC source may be determined by a microcontroller. In some cases the current splitting transformers provide galvanic isolation to the LED assemblies. The multiple LED assemblies may be controlled by a number of switches that may independently activate the individual LED assemblies based on the duty cycle of multiple PWM signals provided to the switches by the microcontroller. When all of the PWM signals output from the microcontroller are on an off-cycle, the current source may be turned off.

Hybrid dimming control techniques for lighting drivers

The present invention provides a lighting fixture including a light source, a light source controller, and an external controller plug. The light source controller controls power to the light source. The external controller plug allows an external controller to selectively engage a power source to the light source controller.

Lighting control

A lamp assembly adapted to operate as one of a total number of lamp assemblies that are connected together in series and connected to a ballast. The lamp assembly comprises an electrodeless, closed-loop, tubular lamp envelope enclosing mercury vapor and a buffer gas, and a transformer core disposed around a portion of the lamp envelope. An input winding is disposed on the transformer core so that it has a particular number of turns, N. An auxiliary winding is disposed on the transformer core so that it has a particular number of turns, N. The auxiliary winding is adapted to connect to the ballast and to couple with the input winding. The ratio of the particular number of turns Nto the particular number of turns Nis substantially proportional to the total number of lamp assemblies that are adapted to operate in series together.

Power splitter circuit for electrodeless lamp

Solid state light source driving and dimming systems are provided that enable a plurality of solid state light source (e.g., LED) driver circuits to be coupled to a single AC voltage source. The driver circuits may include constant current circuitry configured to generate a constant AC current from the AC voltage source, and rectifier circuitry configured to generate a DC current to drive the solid state light source (e.g., LEDs). Dimming control includes shunt circuitry operable with a PWM switch to shunt the AC voltage source during certain portions of a PWM signal and to decouple the shunt circuitry from the AC voltage source during other portions of the PWM signal. Shunting the AC voltage source causes the interruption of the DC current to effectively turn off the LEDs. Decoupling the shunt circuitry may improve overall efficiency of power transfer to the LEDs.

Solid state light source driving and dimming using an AC voltage source

An electrodeless fluorescent lamphas an envelopethat includes a chamber. A coreof magnetic material, preferably ferrite, is positioned in the chamberand has a first windingsurrounding the core and having first and second lead-in wires, attached to a high frequency voltage supply or ballast. A second windingsurrounds the core, respective turns of the second windingbeing located adjacent turns of the first windingand electrically insulated therefrom. The second windinghas a free endand has another endconnected to one of the lead-in wires, for example. A braided sheathsurrounds the other of the lead-in wires. The first windingis generally called the RF antenna. The braided sheathis connected to the local ground. This inexpensive solution alone reduces the conductive EMI level sufficiently to pass all existing regulations on such interference with significant reserve.

RF induction lamp with reduced electromagnetic interference

An electrodeless fluorescent lamp () having a burner (), a ballast housing () containing a ballast () and a screw base () for connection to a power supply. A reentrant cavity () is formed in the burner () and an amalgam receptacle () containing amalgam () is formed as a part of the reentrant portion and in communication with the burner (). A housing cap (), formed of a suitable plastic, connects the burner () to the ballast housing () and a suitable adhesive () fixes the burner to the housing cap (). An EMI cup () is formed as an insert to fit into the ballast housing (), which also is formed of a suitable plastic, and has a bottom portion () and an EMI cap () with an aperture () therein closing an upper portion (). The EMI cup () and the EMI cap () are preferably formed from 0.5 mm brass. The amalgam receptacle () extends through the aperture () and into the cup (). For a fixed amalgam position, changing the aperture size allows adjustment of the amalgam tip temperature, and thus, allows control of the system lumen output, efficacy, CCT and CRI, all of which are dependent on the amalgam temperature.

Re-entrant cavity fluorescent lamp system

An electric lamp assembly includes an electrodeless lamp having an electrodeless lamp envelope enclosing a fill material for supporting a low pressure discharge, a driving inductor including a magnetic core disposed in proximity to the lamp envelope and an input winding disposed on the magnetic core, a compensation loop disposed in proximity to the lamp envelope, a radio frequency power source and a compensation loop network. The compensation loop network has an input coupled to the radio frequency power source and outputs coupled to the input winding and to the compensation loop. The radio frequency power source and the compensation loop network supply radio frequency energy to the electrodeless lamp to produce a discharge in the lamp envelope and supply radio frequency energy to the compensation loop to generate a magnetic field that substantially counteracts a magnetic field produced by the discharge. In one embodiment, the lamp envelope is a closed-loop, tubular lamp envelope, and the magnetic core is disposed around the lamp envelope. In another embodiment, the lamp envelope includes a reentrant cavity, and the magnetic core is disposed in the reentrant cavity.

Electrodeless lamp having compensation loop for suppression of magnetic

An electric lamp assembly includes an electrodeless lamp having a closed-loop, tubular envelope enclosing mercury vapor and a buffer gas at a pressure less than about 0.5 torr, a transformer core disposed around the lamp envelope, an input winding disposed on the transformer core and a radio frequency power source coupled to the input winding. The radio frequency source supplies sufficient radio frequency energy to the mercury vapor and the buffer gas to produce in the lamp envelope a discharge having a discharge current equal to or greater than about 2 amperes. The electrodeless lamp preferably includes a phosphor on an inside surface of the lamp envelope for emitting radiation in a predetermined wavelength range in response to ultraviolet radiation emitted by the discharge.

High intensity electrodeless low pressure light source driven by a

Electrodeless compact fluorescent lamp

A simple and effective technique for reducing an external magnet flux emitted from a driven inductor surrounded by an ionizable gaseous medium. This technique includes surrounding the inductor with at least one shielding conductive loop, terminating the shielding loop in a capacitive termination to resonate, and maintaining a resonant frequency of the capacitive termination in series with an inductance of the shielding loop below the predetermined driving frequency of the inductor.

Growing community of inventors

Brookline, MA, United States of America

Benjamin Alexandrovich