1. A vehicular active noise control system, comprising:
a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle;
an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal;
a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment;
an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound;
a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal;
a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal;
a vehicle speed detector for detecting a vehicle speed of said vehicle and outputting a vehicle speed signal representing said detected vehicle speed; and
a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said vehicle speed signal, and outputting said calculated control frequency to said basic signal generator;
wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event.
2. A vehicular active noise control system, comprising:
a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle;
an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal;
a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment;
an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound;
a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal;
a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal;
an engine rotational speed detector for detecting an engine rotational speed of an engine of said vehicle; and
a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said engine rotational speed, and outputting said calculated control frequency to said basic signal generator;
wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event.
3. A vehicular active noise control system., comprising:
a basic signal generator for generating a basic signal having a predetermined control frequency based on a frequency of a vibratory noise generated by a vibratory noise source of a vehicle;
an adaptive filter for generating a control signal to cancel out an in-compartment noise produced in a passenger compartment of said vehicle by said vibratory noise, based on said basic signal;
a sound outputting device for outputting a canceling sound based on said control signal into said passenger compartment;
an error signal detector for detecting a canceling error sound between said in-compartment noise and said canceling sound and outputting an error signal representing said detected canceling error sound;
a reference signal generator for correcting said basic signal based on a corrective value representing transfer characteristics from said sound outputting device to said error signal detector corresponding to said control frequency, and outputting said corrected basic signal as a reference signal;
a filter coefficient updating unit for sequentially updating a filter coefficient of said adaptive filter to minimize said error signal, based on said error signal and said reference signal;
a vehicle speed detector for detecting a vehicle speed of said vehicle and outputting a vehicle speed signal representing said detected vehicle speed;
an engine rotational speed detector for detecting an engine rotational speed of an engine of said vehicle; and
a frequency calculating unit for calculating said control frequency which is a harmonic of a rotation frequency of a driveline rotary component of said vehicle which serves as said vibratory noise source, based on said vehicle speed signal or said engine rotational speed, and outputting said calculated control frequency to said basic signal generator;
wherein said basic signal generator has a waveform data table for storing waveform data in one cyclic period, and generates said basic signal having said control frequency by successively reading said waveform data from said waveform data table at each sampling event.
4. The vehicular active noise control system according to claim 1, wherein said vehicle speed detector outputs said vehicle speed signal based on a rotational speed of a countershaft.
5. The vehicular active noise control system according to claim 1, wherein said driveline rotary component comprises a propeller shaft, a drive shaft, or a tire.
6. The vehicular active noise control system according to claim 2, wherein said driveline rotary component comprises a propeller shaft, and said frequency calculating unit calculates said rotation frequency of said propeller shaft by multiplying a frequency depending on said engine rotational speed by a transmission gear ratio, a final gear ratio, a bevel gear ratio, and a transfer gear ratio.
7. The vehicular active noise control system according to claim 2, wherein said driveline rotary component comprises a drive shaft or a tire, and said frequency calculating unit calculates said rotation frequency of said drive shaft or said tire by multiplying a frequency depending on said engine rotational speed by a transmission gear ratio or a final gear ratio.
8. The vehicular active noise control system according to claim 6, further comprising:
a connected state output unit for outputting a disconnection signal indicating that said engine and a transmission of said vehicle are disconnected from each other, to said frequency calculating unit;
wherein said frequency calculating unit stops calculating said rotation frequency when said disconnection signal is input thereto.
9. The vehicular active noise control system according to claim 1, wherein said driveline rotary component comprises a propeller shaft, and said frequency calculating unit calculates said rotation frequency of said propeller shaft by multiplying a frequency of said vehicle speed signal by a predetermined conversion value for conversion between a rotational speed of a countershaft and said vehicle speed signal, a final gear ratio, a bevel gear ratio, and a transfer gear ratio.
10. The vehicular active noise control system according to claim 1, wherein said driveline rotary component comprises a drive shaft or a tire, and said frequency calculating unit calculates a rotation frequency of said drive shaft or said tire by multiplying a frequency of said vehicle speed signal by a predetermined conversion value for conversion between a rotational speed of a countershaft and said vehicle speed signal, and a final gear ratio.
11. The vehicular active noise control system according to claim 9, further comprising:
an engine rotational speed detector for detecting an engine rotational speed of an engine of said vehicle; and
a connected state output unit for outputting a disconnection signal indicating that said engine and a transmission of said vehicle are disconnected from each other, to said frequency calculating unit;
wherein said frequency calculating unit calculates said rotation frequency based on said vehicle speed signal or said engine rotational speed when said disconnection signal is not input thereto, and calculates said rotation frequency based on said vehicle speed signal when said disconnection signal is input thereto.
12. The vehicular active noise control system according to claim 1, wherein said control frequency comprises a frequency which is a real multiple of said rotation frequency.
13. The vehicular active noise control system according to claim 1, wherein said control signal comprises a first control signal for canceling out a driveline noise produced in said passenger compartment by said vibratory noise generated by said driveline rotary component, said vehicular active noise control system further comprising:
an active noise control apparatus for generating a second control signal to cancel out an engine noise produced in said passenger compartment by an engine vibratory noise generated by an engine of said vehicle which serves as said vibratory noise source, based on said engine vibratory noise; and
a signal combining unit for combining said first control signal and said second control signal into a combined signal, and outputting said combined signal to said sound outputting device.
14. The vehicular active noise control system according to claim 13, further comprising:
a comparing and adjusting unit for comparing a control frequency of said first control signal and a control frequency of said second control signal with each other, and stopping outputting one of said first and second control signals to said signal combining unit or changing an output level of one of said first and second control signals if said control frequencies of said first and second control signals are the same as or close to each other.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A white polyimide film comprising:
a polyimide base polymer obtained by reacting diamine with dianhydride components, the polyimide base polymer consisting of structures represented by the following formulae (I) and (II):
wherein the ratio of m: n is about 0.95-0.05:0.05-0.95; and
a coloration filler homogeneously distributed in the white polyimide film, the polyimide film having a total transparency value less than about 40%, and a color defined with a b*-value representing a position of the color between yellow and blue that is between about 0 and about 15.
2. The white polyimide film of claim 1, wherein the diamine component is 2,2\u2032-bis(trifluoromethyl)benzidine.
3. The white polyimide film of claim 1, wherein the dianhydride is selected from the group consisting of 3,3\u2032,4,4\u2032-biphenyltetracarboxylic dianhydride and 2,2-bis4-(3,4-dicarboxyphenoxy)phenylpropane dianhydride.
4. The white polyimide film of claim 1, wherein the weight ratio for the filler is between 5% and 70% per polyimide total weight.
5. The white polyimide film of claim 1, further comprising a pigment exhibiting complementary color to the color of the polyimide base polymer.
6. A white polyimide film comprising:
a polyimide base polymer; and
a coloration filler homogeneously distributed in the white polymer film;
wherein the white polyimide film has a coefficient of thermal expansion (CTE) less than about 60 ppm\xb0 C. in a temperature range between about 100 and 200\xb0 C., an elongation rate between about 5 and 60%, a total transparency value less than about 40%, and a color defined with a L*-value representing a lightness of the color more than about 90, and a b*-value representing a position of the color between yellow and blue that is between about 0 and about 15.
7. The white polyimide film of claim 6, having a variation Ab* of the b*-value between about 0 and about 5 in a temperature range between about 250\xb0 C. and about 320\xb0 C.
8. The white polyimide film of claim 6, wherein the polyimide base polymer is obtained by reacting a diamine component including 2,2\u2032-bis(trifluoromethyl)benzidine, and a dianhydride component selected among 3,3\u2032,4,4\u2032-biphenyltetracarboxylic dianhydride and 2,2-bis4-(3,4-dicarboxyphenoxy)phenylpropane dianhydride.
9. The white polyimide film of claim 6, wherein the coloration filler is selected from the group consisting of TiO2, Al2O3, CaCO3, CaSO4, SiO2, BN, MN and clay.
10. The white polyimide film of claim 6, wherein the weight ratio for the coloration filler is between about 5 and about 70% per polyimide total weight.
11. The white polyimide film of claim 6, further comprising a pigment additive presenting complementary color to the color of the polyimide and the coloration filler.
12. A process of manufacturing a white polyimide film, comprising:
performing condensation polymerization of monomers comprising a diamine and a dianhydride to obtain a solution containing polyamic acid;
adding a dehydrant, a catalyst, and a coloration filler into the solution containing the polyamic acid to obtain a precursor solution;
coating a layer of the precursor solution on a support; and
baking the coated layer to form a white polyimide film.
13. The process of claim 12, wherein the step of adding a dehydrant, a catalyst, and a coloration filler further comprises adding a pigment presenting complementary color to the color of the polyimide and the coloration filler.
14. The process of claim 12, wherein the diamine is 2,2\u2032-bis(trifluoromethyl)benzidine.
15. The process of claim 12, wherein the dianhydride is selected from the group consisting of 3,3\u2032,4,4\u2032-biphenyltetracarboxylic dianhydride and 2,2-bis4-(3,4-dicarboxyphenoxy)phenylpropane dianhydride.
16. The process of claim 12, wherein the coloration filler is selected from the group consisting of TiO2, ZrO2, Al2O3, CaO, ZnO2, ZnS2, CaCO3, PbCO3, Pb(OH)2, CaSO4, BaSO4, SiO2, BN, AN basic zinc molybdate, basic calcium zinc molybdate, lead white, molybdenum white, lithopone, and clay.
17. The process of claim 12, wherein the weight ratio for the coloration filler is between about 5 and about 70% per polyimide total weight.
18. The process of claim 12, wherein the step baking the coated layer is performed under a temperature between about 90\xb0 C. and about 350\xb0 C.
19. The process of claim 12, wherein the white polyimide film has a thickness between about 5 \u03bcm and about 150 \u03bcm.
20. The process of claim 12, wherein in the step of adding a dehydrant, a catalyst, and a coloration filler into the solution containing the polyamic acid is performed with a polyamic acid:dehydrant:catalyst molar ratio of about 1:2:1.
21. A white polyimide film comprising:
a polyimide base polymer obtained by reacting diamine with dianhydride components, the polyimide base polymer consisting of structures represented by the following formulae (I) and (II):
wherein the ratio of m:n is about 0.95-0.05:0.05-0.95; and
a coloration filler homogeneously distributed in the white polyimide film with a weight ratio between 5% and 70% per polyimide total weight;
the polyimide film having a total transparency value less than about 40%, and a color defined with a b*-value representing a position of the color between yellow and blue that is between about 0 and about 15, a variation Ab* of the b*-value being between about 0 and about 5 in a temperature range between about 250\xb0 C. and about 320\xb0 C.
22. The white polyimide film of claim 21, wherein the diamine component is 2,2\u2032-bis(trifluoromethyl)benzidine.
23. The white polyimide film of claim 21, wherein the dianhydride is selected from the group consisting of 3,3\u2032,4,4\u2032-biphenyltetracarboxylic dianhydride and 2,2-bis4-(3,4-dicarboxyphenoxy)phenylpropane dianhydride.
24. The white polyimide film of claim 21, wherein the weight ratio for the filler is between 5% and 70% per polyimide total weight.
25. The white polyimide film of claim 21, further comprising a pigment exhibiting complementary color to the color of the polyimide base polymer.
26. The white polyimide film of claim 21, wherein the coloration filler is selected from the group consisting of TiO2, Al2O3, CaCO3, CaSO4, SiO2, BN, AN and clay.
27. The white polyimide film of claim 21, wherein the color is further defined with a L*-value representing a lightness of the color more than about 90.
28. The white polyimide film of claim 21, having a coefficient of thermal expansion (CTE) less than about 60 ppm\xb0 C. in a temperature range between about 100 and 200\xb0 C., and an elongation rate between about 5 and 60%.
29. The white polyimide film of claim 21, wherein the b*-value is as low as between about 1 and about 5.