| 摘要 |
The application of a piezoceramic resonator (PR), connected in parallel to a discharge lamp and in series to cathode filaments of a lamp, provides reliable means of preheating of cathode filaments facilitating a soft start of a fluorescent lamp. The piezoceramic resonator is a polarized piezoceramic element formed in a form of rectangular plate, disk, cylinder, etc. The linear size and shape of the PR determine the type of oscillation, electromechanical resonant frequency and frequency characteristics. The PRs with radial, contour or longitudinal oscillations are best suited for application to a piezoelectronic ballast. Piezoceramic resonators and filters as frequency-selective elements in measuring and radio communication instruments are widely used in weak alternating electrical fields, where the intensity of field does not exceed an order of volts per mm. The present invention offers the use of a piezoceramic resonator in power electronics as in an electronic ballast where the electrical field intensity reaches an order of hundred volts per mm of thickness of a piezoceramic element. Expansion of frequency band width of resonant characteristic of the PR are achieved by using several piezoceramic resonators with different frequency characteristics in parallel and further by constraining oscillation of piezoceramic resonators mechanically.
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