| 摘要 |
RD-19,991 PIEZOELECTRICALLY ACTUATED VARIABLE CAPACITOR A variable capacitor comprises a fixed conductive plate and a movable conductive plate with a dielectric disposed between them. A piezoelectric actuator is used to vary the distance between the conductive plates by moving the movable plate with respect to the fixed plate, with capacitance changing in inverse proportion to distance moved. In an electrodeless high intensity discharge lamp ballast, such a variable capacitor is situated in series with the excitation coil of the lamp. When a control voltage is applied to the piezoelectric actuator, the movable plate is moved from a starting position to a running position to a to maintain the ballast load in tune under both starting and running conditions, respectively, resulting in higher efficiency operation.
|
