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US 6,584,206 B2Granted
Speaker apparatus
AssigneeSony Corporation
InventorYoshio Ohashi
Life of this patent
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Abstract
A fixed electrode is divided into a plurality of electrode pieces and driving signals of different voltages are applied to the electrode pieces such that a distribution of driving forces applied to a vibrator is proportional to the surface displacement distribution in a vibration mode across the vibrator.
Claims3
A speaker apparatus for generating sound pressure, comprising:
- a pair of fixed electrodes;
- a vibrator arranged between the pair of fixed electrodes and separated therefrom by a spacing;
- and
- means for producing a driving signal applied to the fixed electrodes and producing a bias voltage applied between an electrode of the vibrator and the pair of fixed electrodes to cause a driving force corresponding to the driving signal to be applied to the vibrator, wherein
- each of the pair of fixed electrode is divided into a plurality of electrode pieces, wherein
- said means for producing a driving signal includes a transformer having a plurality of secondary outputs producing a plurality of driving signals applied respectively to the plurality of electrode pieces, and wherein
- voltages of the plurality of driving signals applied to the plurality of electrode pieces are weighted so that driving forces applied to the vibrator are proportional to a surface displacement distribution in a unique vibration mode of the vibrator given by:
- Ξ m , n = sin m π a x · sin n π b y
- where m and n are integers indicating an order of the unique vibration mode of the vibrator, and where a and b are the lengths of the size of the vibrator in the x-axis direction and in the y-axis direction, respectively.
6 more elements
Dependencies are inferred from the claim text.