Loudspeaker and method of driving the same as well as audio signal transmitting/receiving apparatus

A loudspeaker apparatus comprising:

• first modulating means for frequency-modulating an audio signal and producing a first output signal of a frequency band higher than an audible frequency band;
• second modulating means including an inverter for frequency modulating the audio signal and producing a second output signal of a frequency band higher than the audible frequency band;
• correction means receiving the first and second output signals from said first and second modulating means and producing corrected output signals;
• and
• ultrasonic generating means driven by the corrected output signal of said correction means for producing ultrasonic waves.

A loudspeaker apparatus comprising:

• modulating means including a first modulating section and a second modulating section, one of said first modulating section and said second modulating section being supplied with an audio signal, the other of said first modulating section and said second modulating section being supplied with a signal obtained by inverting said audio signal, whereby said audio signal is frequency-modulated into a signal of a frequency band higher than an audible frequency band;
• and
• ultrasonic generating means driven by an output signal of said modulating means, wherein
• said ultrasonic generating means includes a first generating section including a first plurality of ultrasonic generating devices driven by an output signal of said first modulating section and a second generating section including a second plurality of ultrasonic generating devices driven by an output signal of said second modulating section.

A method of driving a loudspeaker apparatus having an ultrasonic generating device, said method comprising:

• a first step of frequency-modulating an input audio signal into a first signal of a frequency band higher than an audible frequency band;
• a second step of frequency modulating the input audio signal into a second signal, inverted relative to said first signal, of a frequency band higher than the audible frequency band;
• and
• a subsequent step of driving an ultrasonic generating device by said first and second signals obtained in the first and second steps of frequency-modulating.