Vehicular active sound control apparatus

Abstract

A vehicular active sound control apparatus has a controller which opens a switch to prevent an uncomfortable sound from being generated by a speaker based on a control signal if the value of a drive signal for the speaker has exceeded a predetermined threshold successively a predetermined number of times.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a vehicular active sound control apparatus according to a first embodiment of the present invention;

FIG. 2A is a diagram showing a measured gain characteristic curve;

FIG. 2B is a diagram showing a gain characteristic curve which is an inversion of the measured gain characteristic curve;

FIG. 2C is a diagram showing a corrected gain characteristic curve;

FIG. 2D is a diagram showing a gain characteristic curve with enhanced gains in a certain frequency range;

FIG. 2E is a diagram showing the inverted gain characteristic curve with enhanced gains in the certain frequency range;

FIG. 3A is a diagram showing waveform data stored in a waveform data memory of the vehicular active sound control apparatus;

FIG. 3B is a diagram showing a sine wave which is generated by referring to the waveform data memory;

FIG. 4 is a diagram showing the frequency characteristics of sound pressure levels before and after they are corrected;

FIG. 5 is a flowchart of an operation sequence of the vehicular active sound control apparatus according to the first embodiment;

FIG. 6 is a diagram showing a waveform illustrative of the operation sequence of the vehicular active sound control apparatus according to the first embodiment;

FIG. 7 is a block diagram of a vehicular active sound control apparatus according to a second embodiment of the present invention; and

FIG. 8 is a flowchart of an operation sequence of the vehicular active sound control apparatus according to the second embodiment.

Claims

1. A vehicular active sound control apparatus comprising: a waveform data table for storing waveform data in one cyclic period;reference signal generating means for generating a reference signal by successively reading the waveform data from said waveform data table;running state detecting means for detecting a running state of a vehicle;control means for generating a control signal by acoustically changing said reference signal depending on the running state of the vehicle detected by said running state detecting means; andoutput means for acoustically outputting a drive signal based on said control signal;wherein said control means inhibits said control signal from being generated if a value of said drive signal has exceeded a predetermined threshold successively a predetermined number of times.

2. A vehicular active sound control apparatus according to claim 1, further comprising alarm means for generating an alarm signal, wherein said control means activates said alarm means if the value of said drive signal has exceeded the predetermined threshold successively the predetermined number of times.

3. A vehicular active sound control apparatus according to claim 1, further comprising an amplifier for amplifying said control signal at a predetermined amplification ratio and outputting the amplified control signal, wherein said drive signal comprises said amplified control signal.

4. A vehicular active sound control apparatus according to claim 1, further comprising: a vehicular entertainment system including an audio signal source; anda mixer for mixing an audio signal from said audio signal source and said control signal or an amplified control signal with each other and outputting a mixed signal;wherein said drive signal comprises said mixed signal.

5. A vehicular active sound control apparatus comprising: a waveform data table for storing waveform data in one cyclic period;reference signal generating means for generating a reference signal by successively reading the waveform data from said waveform data table;running state detecting means for detecting a running state of a vehicle;control means for generating a control signal by acoustically changing said reference signal depending on the running state of the vehicle detected by said running state detecting means; andoutput means for acoustically outputting a drive signal based on said control signal;wherein said control means calculates an amplification ratio of said control signal and said drive signal, and adjusts a value of said control signal depending on the calculated amplification ratio.

6. A vehicular active sound control apparatus according to claim 5, further comprising alarm means for generating an alarm signal, wherein said control means activates said alarm means if said amplification ratio exceeds a predetermined value.

7. A vehicular active sound control apparatus according to claim 5, further comprising an amplifier for amplifying said control signal at a predetermined amplification ratio and outputting the amplified control signal, wherein said drive signal comprises said amplified control signal.

8. A vehicular active sound control apparatus according to claim 5, further comprising: a vehicular entertainment system including an audio signal source; anda mixer for mixing an audio signal from said audio signal source and said control signal or an amplified control signal with each other and outputting a mixed signal;wherein said drive signal comprises said mixed signal.