Abstract: A flexible seal intended to be fixed between a fixed part and a mobile part of an aircraft, the seal comprising an elongate hollow body, a shoe secured to the hollow body, intended to be fixed to the fixed part, a blade secured to the hollow body and designed to extend from the hollow body towards the mobile part, the blade having a leak edge having a non-linear edge, such as with notches or chevrons. The provision of a notched leak edge reduces a pressure differential on either side of the blade, and by allowing the air to pass between the blade and the fixed part just before the contact with the fixed part, the lifting of the blade is prevented.

Abstract: An electronic ballast for fluorescent lighting includes an inverter circuit having an output circuit coupled to a pair of lamp terminals. A protection circuit is coupled to one of the lamp terminals. The protection circuit includes a differential voltage sensing circuit that is functional to sense the lamp voltage pulses as sudden changes in voltage across a DC blocking capacitor and, in response, to provide a positive AC voltage pulse. A pulse accumulation circuit is coupled to the differential voltage sensing circuit. The pulse accumulation circuit is responsive to the positive AC voltage pulses from the differential voltage sensing circuit to accumulate the positive AC voltage pulses into the ballast shutdown signal.

Abstract: A zone addressing circuit is provided for an electronic ballast having a boost inductor with an auxiliary winding. The zone addressing circuit includes a first circuit branch coupled to a first addressing input terminal, a second circuit branch coupled to a second addressing input terminal, and a third (common) branch coupled on a first end to a third addressing input terminal and on a second end to the auxiliary winding of the boost inductor for providing a high frequency input pulse signal to excite the first and second branches. The first branch generates a first digital output for the zone addressing circuit when coupled to the common branch, and the second branch generates a second digital output for the zone addressing circuit when coupled to the common branch. A controller adjusts a dimming level of the ballast based on the first and second digital outputs from the zone addressing circuit.

Abstract: A ballast circuit includes a control loop to reduce a filament heating voltage below after the lamp filaments have been pre-heated. A filament cutback circuit includes a filament cut-back inductive component magnetically coupled to the resonant inductive component in the inverter to receive a filament cutback control voltage associated with an AC voltage for powering the lamps. During the pre-heating period, the filament cutback control voltage is not high enough to charge a chargeable component to a switch threshold level. However, during lamp ignition, the filament cutback control voltage is increased and charges the chargeable component to the switch threshold level. This causes a switch device to operate in a conductive switch state and the filament cutback circuit suppresses the pre-heat voltage.

Abstract: A circuit for preheating filaments in lamps powered by an electronic ballast includes an inverter tank circuit and a preheat tank circuit. The preheat tank circuit has a preheat capacitor connected in parallel with a primary winding of a filament preheat transformer. A cut-back capacitor is connected between the preheat tank circuit and circuit ground. The filament preheat transformer has secondary windings coupled to the first and second lamp terminals to provide a filament preheat voltage. The inverter operates at a preheat frequency during a lamp preheat mode and at a steady-state frequency during a lamp steady-state mode, the steady-state frequency being lower than the preheat frequency. The preheat tank circuit has a natural resonant frequency that is approximately the same as the preheat frequency so that when the ballast is operating in the steady state mode, the filament voltage is substantially lower than when the ballast is operating in the preheat mode.

Abstract: A constant current source mirror tank dimmable ballast operates multiple high impedance lamps in a stable and balanced manner. The dimmable ballast has an inverter connected to two third-order resonant circuits. These third-order resonant circuits dominate the transfer function of the ballast circuits. Consequently, changes in the impedance of the lamp do not affect the current output to the lamps.

Abstract: A step dimming interface is utilized to operate a load such as a gas discharge lamp. The dimming interface has first and second switches for determining when the gas discharge lamp operates at either a normal power level or a dimming power level. A rectifier circuit is connected to a control signal production circuit. By manipulating the first and second switches, the rectifier sends either a full-wave rectified signal or a half-wave rectified signal to the control signal production circuit which determines the output of the control signal production circuit. The control signal production circuit may be connected to an electronic ballast which varies the power level of the lamp according to this output.