| Patent application number | Description | Published |
|---|
| 20090322228 | False Failure Prevention Circuit In Emergency Ballast - A backup ballast used with a primary ballast for providing power to one or more lamps. The backup ballast includes an output switch and a delay circuit. The output switch has a first operating mode for connecting a primary power source via the primary ballast to a first set of the lamps and second operating mode for connecting a backup power source with a second set of the lamps. The output switch operates in the first operating mode when it is energized and in the second operating mode when said it is not energized. The delay circuit is adapted for connecting to the primary power source for receiving power therefrom. The delay circuit is connected to the output switch for energizing it while the power is being received and for a delay period thereafter. The delay circuit includes an energy-storage component for storing energy while the power is being received and discharging the stored energy when the power is not being received in order to energize the output switch for the delay period. | 12-31-2009 |
| 20100301752 | RESETTING AN ELECTRONIC BALLAST IN THE EVENT OF FAULT - A ballast for driving one or more lamps includes a controller and a current reduction circuit for accelerating a controller reset. Upon detecting a fault, the controller disables the ballast for a preset period of time, and resets. The controller additionally resets when the ratio of a supplied second value to a supplied first value falls below a threshold value. The current reduction circuit reduces the supplied second value in less than the preset period of time, such that the ratio falls below the threshold value and the controller resets. An emergency lighting system includes the ballast as a primary ballast, a backup ballast, and a primary power source. The controller detects a fault if the primary power source de-energizes and the backup ballast disconnects the one or more lamps from the primary ballast. The current reduction circuit accelerates the reset of the controller when the primary power source de-energizes. | 12-02-2010 |
| 20100301754 | Electronic Ballast Control Circuit - A control circuit for use in a ballast configured for powering a first lamp set and a second lamp set. The second lamp set is operated via a controller and a second lamp driver circuit. The controller enables the second lamp driver circuit as a function of a monitored value corresponding to a current through a lamp of the second lamp set. The control circuit includes first and second input terminals for selectively connecting to the power supply. The control circuit reduces the monitored value as a function of a connection state of the first and second input terminals of the control circuit to the power supply. Thus, the control circuit causes the controller to selectively operate the second lamp driver circuit in order to energize the second lamp set in combination with the first lamp set. | 12-02-2010 |
| 20100301759 | RESTART CIRCUIT FOR MULTIPLE LAMP ELECTRONIC BALLAST - A restart circuit for causing an electronic ballast to perform a restart in response to reconnecting any lamp of a multiple lamp configuration of the electronic ballast to the electronic ballast is disclosed. The electronic ballast includes a filament health check circuit for providing a first current through a monitored filament of the lamps to a controller of the ballast. The controller restarts the electronic ballast when a determined ratio of the first current to a reference current indicates that the monitored filament has been disconnected or broken (i.e., the first current substantially decreases) and is subsequently replaced or reconnected to the ballast (i.e., the first current returns to a predetermined level). The ballast further comprises a dv/dt circuit for reducing the first current for a transient time period in response to reconnecting a filament other than the monitored filament to the ballast, causing the controller to restart the ballast. | 12-02-2010 |
| 20110163685 | Lamp End of Life (EOL) Detection Circuit - A lamp driver circuit to selectively energize one or more lamps is provided. The inverter circuit has a transformer with primary and secondary windings to provide voltage to the lamps. A filter is connected to the primary winding to receive a primary winding signal representative of the voltage across the primary winding. The primary winding signal has a frequency spectrum and the filter detects a particular characteristic of the frequency spectrum that is indicative of an end of life (EOL) condition of the one or more lamps. A control circuit is connected to the inverter circuit and to the filter. The control circuit is configured to discontinue energizing of the one or more lamps by the inverter circuit when the particular characteristic of the frequency spectrum of the primary winding signal is detected by the filter. | 07-07-2011 |
