Active noise control apparatus for domestic appliance
First Claim
1. An apparatus for actively controlling noise generated by an electromagnetic machine, said noise being apt to externally leak from an opening of a machine room storing said electromagnetic machine driven by an AC power supply, said apparatus comprising:
- electro-acoustic conversion means for applying a predetermined sound wave to the opening of said machine room;
detection means for detecting a frequency of an AC voltage waveform to be applied to said electromagnetic machine driven by said AC power supply;
noise correspondence signal generating means for generating, according to a detection signal from said detection means, an output signal correlative with an electromagnetic noise component included in noise generated by said electromagnetic machine; and
additional tone signal generating means for generating, according to said output signal from said noise correlative signal generating means, an additional tone signal for causing said electro-acoustic conversion means to apply a sound wave essentially having both a phase opposite to and the same amplitude as of the electromagnetic noise component propagating toward the opening of said machine room.
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Accused Products
Abstract
An apparatus includes an electro-acoustic converter, a detector, a noise correlative signal generator, and an additional tone signal generator in order to actively control noise generated by an electromagnetic machine, which noise is apt to externally leak from an opening of a machine room storing the electromagnetic machine driven by an AC power supply. The electro-acoustic converter applies a predetermined sound wave to the opening of the machine room. The detector essentially detects a frequency of an AC voltage waveform to be applied to the electromagnetic machine driven by the AC power supply. The noise correlative signal generator generates generating a signal correlative with an electromagnetic noise component included in noise generated by the electromagnetic machine according to a detection signal from the detector. The additional tone signal generator generates, according to an output signal from the noise correlative signal generator, an additional tone signal for causing the electro-acoustic converter to apply a sound wave essentially having a phase opposite to and the same amplitude as those of the electromagnetic noise component at the opening of the machine room.
25 Citations
13 Claims
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1. An apparatus for actively controlling noise generated by an electromagnetic machine, said noise being apt to externally leak from an opening of a machine room storing said electromagnetic machine driven by an AC power supply, said apparatus comprising:
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electro-acoustic conversion means for applying a predetermined sound wave to the opening of said machine room; detection means for detecting a frequency of an AC voltage waveform to be applied to said electromagnetic machine driven by said AC power supply; noise correspondence signal generating means for generating, according to a detection signal from said detection means, an output signal correlative with an electromagnetic noise component included in noise generated by said electromagnetic machine; and additional tone signal generating means for generating, according to said output signal from said noise correlative signal generating means, an additional tone signal for causing said electro-acoustic conversion means to apply a sound wave essentially having both a phase opposite to and the same amplitude as of the electromagnetic noise component propagating toward the opening of said machine room. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for actively controlling noise generated by an electromagnetic machine, said noise being apt to externally leak from an opening of a machine room storing said electromagnetic machine driven by an AC power supply, said apparatus comprising:
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electro-acoustic conversion means for applying a predetermined sound wave to the opening of said machine room; detection means for detecting an AC voltage waveform and an AC current waveform to be applied to said electromagnetic machine driven by said AC power supply; noise correspondence signal generating means for generating, according to a detection signal from said detection means, an output signal having a spectrum corresponding to a combination of both an electromagnetic noise component and a rotational noise component generated by said electromagnetic machine; and additional tone signal generating means for generating according to said output signal from said noise correspondence signal generating means, an additional tone signal for causing said electro-acoustic conversion means to apply a sound wave essentially having a phase opposite to and the same amplitude as those of the combination of both the electromagnetic noise component and the rotational noise component propagating toward the opening of said machine room. - View Dependent Claims (10, 11, 12, 13)
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Specification