| 摘要 |
New transducers are proposed, of the kind having an array of transducer cells for generating an ultrasonic beam, modulated with an audio frequency. The cells may be bipolar, with certain cells 21 connected to receive a driver signal with a first polarity and other cells 25 connected to receive the driver signal with the opposite polarity, so that the two sorts of cell radiate in anti-phase. Alternatively, the cells may be partitioned into sets, each set of cells receiving the driving signal amplified by a corresponding amplifier 32, with a corresponding real weighting value.
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