System for reducing noise level in vehicular cabin
First Claim
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1. A system for lowering cabin noise in a vehicular cabin, comprising:
- first means for periodically generating a first pulse signal in synchronism with an engine revolution, said first pulse signal having a period proportional to a noise period created by vibration induced in synchronization with said engine revolution;
second means including a flip-flop, in response to the first pulse signal, for generating a rectangular waveform signal having a 50% duty ratio and a rising edge and falling edge being in conformity to a rising edge and subsequent rising edge of said first pulse signal, respectively;
third means for converting said rectangular waveform signal into a digital signal representative thereof; and
fourth means for processing said digital signal for adjusting signal phase and amplitude and outputting adjusted digital signal for canceling the noise created by vibration.
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Abstract
A system for lowering noise level in a vehicular cabin produces an acoustic vibration canceling noise creative vibration induced in synchronism with an engine revolution. The system generates a rectangular wave signal having 50% duty cycle. The system includes means for producing a periodic signal having an interval half of a period of the noise created by vibration. The signal level of the rectangular signal is switched between HIGH and LOW levels alternatively at the time of occurrence of the periodic signal.
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10 Claims
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1. A system for lowering cabin noise in a vehicular cabin, comprising:
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first means for periodically generating a first pulse signal in synchronism with an engine revolution, said first pulse signal having a period proportional to a noise period created by vibration induced in synchronization with said engine revolution; second means including a flip-flop, in response to the first pulse signal, for generating a rectangular waveform signal having a 50% duty ratio and a rising edge and falling edge being in conformity to a rising edge and subsequent rising edge of said first pulse signal, respectively; third means for converting said rectangular waveform signal into a digital signal representative thereof; and fourth means for processing said digital signal for adjusting signal phase and amplitude and outputting adjusted digital signal for canceling the noise created by vibration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification