1. A method of identifying a sequence of formant values for a sequence of phonetic units, the method comprising:
identifying a sequence of target values for a formant; and
applying the sequence of target values to a finite impulse response filter to produce a sequence of formant values.
2. The method of claim 1 wherein applying the sequence of target values to a finite impulse response filter comprises applying the sequence of target values to a finite impulse response filter that generates a value based on past target values and future target values.
3. The method of claim 2 wherein the finite impulse response is symmetrical with respect to past target values relative to future target values.
4. The method of claim 1 wherein identifying a sequence of target values comprises identifying a separate target value for each phonetic unit in the sequence of phonetic units.
5. The method of claim 1 wherein identifying a sequence of target values further comprises determining a duration for each target value in the sequence of target values.
6. The method of claim 1 wherein identifying a sequence of formant values forms part of a process for synthesizing speech.
7. The method of claim 1 wherein the response of the finite impulse response filter produces undershoot in the sequence of formant values relative to the sequence of target values.
8. A computer-readable medium having computer-executable instructions for performing steps comprising:
identifying a sequence of target formant values; and
at a point in the sequence of target formant values, determining a formant trajectory value using multiple target formant values that occur before the point in the sequence of target formant values and using multiple target formant values that occur after the point in the sequence of target formant values.
9. The computer-readable medium of claim 8 wherein determining a formant trajectory value comprises applying the sequence of target formant values to a finite impulse response filter.
10. The computer-readable medium of claim 9 wherein the response of the finite impulse response filter is dependent on a phonetic unit associated with a target formant value.
11. The computer-readable medium of claim 9 wherein the finite impulse response filter uses the same number of target formant values that occur before the point as the number of target formant values that occur after the point.
12. The computer-readable medium of claim 11 wherein the response of the finite impulse response filter is symmetrical.
13. The computer-readable medium of claim 8 wherein identifying a sequence of target formant values comprises identifying a sequence of phonetic units and identifying the sequence of target formant values from the sequence of phonetic units.
14. The computer-readable medium of claim 13 wherein identifying a sequence of phonetic units further comprises identifying a duration for each phonetic unit.
15. The computer-readable medium of claim 8 further comprising determining a sequence of formant trajectory values.
16. The computer-readable medium of claim 15 wherein the sequence of target formant trajectory values is based in part on a rate of speech and the sequence of formant trajectory values exhibits formant reduction with changes in the rate of speech.
17. A method of synthesizing speech, the method comprising:
identifying a sequence of phonetic units;
identifying a sequence of target formant values from the sequence of phonetic units;
applying the sequence of target formant values to a finite impulse response filter to form a sequence of formant trajectory values;
using the sequence of formant trajectory values to control a filter; and
applying an excitation signal to the filter to form a speech signal.
18. The method of claim 17 wherein the finite impulse response filter uses past target formant values and future target formant values to form a current formant trajectory value.
19. The method of claim 18 wherein the finite impulse response filter is symmetrical with respect to the past target formant values and the future target formant values.
20. The method of claim 18 wherein the response of the finite impulse response filter changes depending on the phonetic unit associated with the trajectory formant value.
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 liquid-crystalline medium having a helically twisted structure comprising a nematic component and an optically active component, wherein the optically active component comprises one or more chiral compounds whose helical twisting power and concentration are selected in such a way that the helical pitch of the medium is \u22661 \u03bcm, and the nematic component comprises at least 75% by weight of one or more compounds containing a 3,4,5-trifluorophenyl group
selected from the following formulae
in which
Z3 in each case, independently of one another, denotes COO, C2H4, CF2O or C2F4, and
Z4 in each case, independently of one another, denotes COO, CF2O, C2F4 or a single bond,
R0 denotes H or an alkyl or alkenyl radical having 1 to 20 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by \u2014O\u2014, \u2014S\u2014, \u2014CO\u2014, \u2014CO\u2014O\u2014, \u2014O\u2014CO\u2014, \u2014O\u2014CO\u2014O\u2014, \u2014CH\u2550CH\u2014 or \u2014C\u2261C\u2014 in such a way that O atoms are not linked directly to one another,
Y3 to Y4 each, independently of one another, denote H or F,
Y1, Y2 denote F,
X0 denotes F, and
a denotes 0 or 1.
2. A liquid-crystalline medium of claim 1 wherein the nematic component comprises one or more compounds of the formula I
in which
R0 denotes H or an alkyl or alkenyl radical having 1 to 20 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by \u2014O\u2014, \u2014S\u2014, \u2014CO\u2014, \u2014CO\u2014O\u2014, \u2014O\u2014CO\u2014, \u2014O\u2014CO\u2014O\u2014, \u2014CH\u2550CH\u2014 or \u2014C\u2261C\u2014 in such a way that O atoms are not linked directly to one another,
each, independently of one another, denote
Y1 to Y4 each, independently of one another, denote H or F,
Z1 and Z2 each, independently of one another, denote \u2014O\u2014, \u2014S\u2014, \u2014CO\u2014, \u2014COO\u2014, \u2014OCO\u2014, \u2014S\u2014CO\u2014, \u2014CO\u2014S\u2014, \u2014OCH2\u2014, \u2014CH2O\u2014, \u2014SCH2\u2014, \u2014CH2S\u2014, \u2014CF2O\u2014, \u2014OCF2\u2014, \u2014CF2S\u2014, \u2014SCF2\u2014, \u2014CH2CH2\u2014, \u2014CF2CH2\u2014, \u2014CH2CF2\u2014, \u2014CF2CF2\u2014, \u2014CH\u2550CH\u2014, \u2014CF\u2550CH\u2014, \u2014CH\u2550CF\u2014, \u2014CF\u2550CF\u2014, \u2014C\u2261C\u2014 or a single bond,
X0 denotes F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 C atoms,
a denotes 0 or 1, and wherein the compounds of the formula I are different from the compounds of the formulae I1, I2 and I3.
3. A medium according to claim 2, comprising one or more compounds selected from the following formula
in which R0 and X0 have the meaning indicated in claim 2.
4. A medium according to claim 2, further comprising one or more compounds of the following formula
in which R0, X0, Y1, Y2, Y3 and Y4 have the meaning indicated in claim 2.
5. A medium according to claim 1, wherein the nematic component comprises
5 to 50% of compounds of the formula I1,
5 to 45% of compounds of the formula I2,
10 to 65% of compounds of the formula I3, and
3 to 40% of compounds of the formula II
in which
R0 denotes H or an alkyl or alkenyl radical having 1 to 20 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by \u2014O\u2014, \u2014S\u2014, \u2014CO\u2014, \u2014CO\u2014O\u2014, \u2014O\u2014CO\u2014, \u2014O\u2014CO\u2014O\u2014, \u2014CH\u2550CH\u2014 or \u2014C\u2261C\u2014
in such a way that O atoms are not linked directly to one another,
Y1 to Y4 each, independently of one another, denote H or F, and
X0 denotes F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 C atoms.
6. A medium according to claim 1, wherein the medium has a reflection wavelength in the range from 400 to 800 nm.
7. A medium according to claim 1, further comprising one or more dyes.
8. An electro-optical, laser-optical or nonlinear-optical device comprising a medium according to claim 1.
9. An electro-optical liquid-crystal display containing a medium according to claim 1.
10. An electro-optical liquid-crystal display according to claim 9, that is a cholesteric, SSCT, PSCT or flexoelectric display.
11. An electro-optical liquid-crystal display according to claim 9, that is an active-matrix display.
12. An active laser material or resonator for laser applications, containing a medium according to claim 1, wherein said medium is a cholesteric liquid crystal medium.
13. A laser arrangement or an active laser material or a resonator therefore containing a medium according to claim 1.
14. A medium according to claim 4, wherein X0 in the formula ha denotes OCF3 and X0in the formulae I1b, I2a, I2k, I3a, I3b and I3c denotes F.
15. A medium according to claim 2, comprising at least one compound of formula I in which X0, Y1 and Y2 denote F, and at least one compound of the formula I in which X0 denotes Cl, CF3, OCF3 or OCHF2.
16. A medium according to claim 2, wherein Z1 and Z2 denote \u2014COO\u2014, \u2014OCO\u2014, \u2014OCH2\u2014, \u2014CH2O\u2014, \u2014CF2O\u2014, \u2014OCF2\u2014, \u2014CH2CH2\u2014, \u2014CF2CH2\u2014, \u2014CH2CF2\u2014, \u2014CF2CF2\u2014 or a single bond.
17. A medium according to claim 2, wherein the nematic component comprises one or more compounds of formula I, wherein Y1, Y2 and X0 are fluoro, as compounds containing a 3,4,5 -trifluorophenyl group.
18. A medium according to claim 1, wherein R0is n-alkyl, alkoxy, fluoroalkyl, alkenyl or oxaalkenyl, each having up to 9 C atoms.
19. A liquid-crystalline medium according to claim 1, wherein a is 1.
20. A liquid-crystalline medium according to claim 1, wherein the amount of compounds of formula 11-13 is at least 80%.