US5309265A
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Short pitch LC layer with a temperature independent λ0 and containing a nematic LC doped with plural chiral additives having the same twist sense
Assignee: Rolic Technologies Ltd
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Filing: 1992-11-23
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Granted: 1994-05-03
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Expires: 2012-11-23
Abstract
Abstract Small-pitch cholesteric liquid crystal mixtures are temperature compensated. They are particularly useful when no, or only a slight, temperature dependence of the selective reflection is permissible, because a considerable temperature dependence would interfere with or render wanted effects impossible. They are composed of a nematic liquid crystal doped with at least two chiral additives satisfying the following conditions: (1) a(c1B1+c2B2)=b(c1A1+c2A2) and (2) 1/ lambda o(T)=a(c1A1+c2A2)+aT(c1B1+c2B2)+bT(c1A1+c2A2) where lambda o denotes the mean value of the wavelength band of the selective reflection c1c2, . . . denote the concentrations of the chiral dopants and A1,B1 are coefficients of a progression.
Inventors
- 👤 Richard Buchecker
- 👤 Jurg Funfschilling
- 👤 Martin Schadt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:09
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/137; G02F1/139; G02F1/1396; C; C09; C09K; C09K19/00; C09K19/02; C09K19/52; C09K19/58; G02B; G02B5/00; G02B5/30; G02B5/3016; G02F1/0009; G02F1/0063; G02F1/133; G02F1/1333; G02F1/133382; G02F1/1335; G02F1/133528; G02F1/133536; G02F1/133543
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
155 words
A liquid crystal layer containing a liquid crystal composition with a central wavelength of selective reflection λ o wherein said liquid crystal layer has a short pitch (p) equal to about one order of magnitude less than the layer thickness; said liquid crystal composition comprises a nematic liquid crystal compound doped with at least two chiral additives of the same twist sense, wherein said composition has the parameters a and b where a is the reciprocal of the refractive index of 22° C. and b is the linear temperature coefficient of the reciprocal of the refractive index and each chiral additive (k) has the parameters A K and B K and A K is the twisting power (1/p) at 22° C. and B k is the liner temperature coefficient of the twisting power; and the parameters a, b, A K and B k are such that λ o is temperature compensated to have temperature independence.
Claim 2
Dependent Claim
155 words
A liquid crystal layer containing a liquid crystal composition with a central wavelength of selective reflection λ o wherein said liquid crystal layer has a short pitch (p) equal to about one order of magnitude less than the layer thickness; said liquid crystal composition comprises a nematic liquid crystal compound doped with at least two chiral additives of the same twist sense, wherein said composition has the parameters a and b where a is the reciprocal of the refractive index of 22° C. and b is the linear temperature coefficient of the reciprocal of the refractive index and each chiral additive (k) has the parameters A K and B K and A K is the twisting power (1/p) at 22° C. and B k is the liner temperature coefficient of the twisting power; and the parameters a, b, A K and B k are such that λ o is temperature compensated to have temperature independence.
Claim 3
Dependent Claim
44 words
The liquid crystal layer of claim 1, wherein there are only two additives which have the respective concentrations c 1 and c 2 and satisfy the condition a(c 1 B 1 +c 2 B 2 )=b(c 1 A 1 +c 2 A 2 ).
Claim 4
Dependent Claim
23 words
The liquid crystal layer according to claim 1, wherein the chiral additives are: a. diethyl (4S,5S)-2-trans-4-(p-cyanophenyl)cyclohexyl]-1,3-dioxolane-4,5-dicarboxylate, b. (R)-1-methylheptyl-p-[(2S,4R,5S)-5-decyl-4-methyl-m-dioxan-2-yl]benzoate, c. 2,2'-p-phenylenebis[(2S,4R,5S)-4-methyl-5-octyl-m-dioxane], and d. (R)-alpha-methylheptyl-4'-[(2S,4R,5S)-4-methyl-5-octyl-m-dioxan-2-yl]-4-biphenylcarboxylate.
References Cited (Backward Citations)
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US4780240A
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EP0217240A1
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EP0218132A1
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US4939287A
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EP0351746A1
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-05-02 | 1997-11-01 | 1998-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-02 | 2001-11-01 | 2002-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-02 | 2005-11-01 | 2006-05-03 | $7700.00 | Window Closed / Lapsed |