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US5200848A
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Ferroelectric smectic liquid crystal device
Assignee: Canon Inc
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Filing: 1990-03-19
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Granted: 1993-04-06
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Expires: 2010-03-19
Abstract
Abstract A ferroelectric smectic liquid crystal device having an improved impact resistance and an improved contrast is provided by using a pair of substrates provided with uniaxial alignment axes which are parallel and identical in direction with each other. A ferroelectric smectic liquid crystal is disposed between the pair of substrates so as to assume a higher-temperature alignment state and a lower-temperature alignment state on temperature decrease in its ferroelectric smectic phase placed in a bistable alignment state. The ferroelectric smectic liquid crystal is further placed in the lower-temperature alignment state which is characterized by having an inclination of forming a connected pair of a lightning defect and a hair pin defect coming after the lightning defect.
Inventors
- 👤 Yukio Hanyu
- 👤 Junichiro Kanbe
- 👤 Hideyuki Kawagishi
- 👤 Yutaka Inaba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:06
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1039; C08G73/1046; C08G73/105; C08G73/1053; C08G73/1067; G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/1337; G02F1/133711; G02F1/133723; G02F1/137; G02F1/139; G02F1/141; G02F1/1416; C09; C09K; C09K2323/00; C09K2323/02; C09K2323/027; C09K2323/0271
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
135 words
A process for preparing a chiral smectic liquid crystal device, comprising the steps of: (a) providing a pair of substrates, each having a uniaxial alignment axis, said uniaxial alignment axes being parallel and identical in direction with each other; (b) disposing between the pair of substrates a chiral smectic liquid crystal capable of forming a higher-temperature alignment state and a lower-temperature alignment state in its chiral smectic phase; and (c) cooling the chiral smectic liquid crystal from a phase having a temperature higher than the chiral smectic phase to place the chiral smectic liquid crystal first in the higher-temperature alignment state and then further cooling the chiral smectic liquid crystal to place the liquid crystal in the lower-temperature alignment state in the chiral smectic phase in a bistable alignment state providing two stable orientation states.
Claim 2
Dependent Claim
135 words
A process for preparing a chiral smectic liquid crystal device, comprising the steps of: (a) providing a pair of substrates, each having a uniaxial alignment axis, said uniaxial alignment axes being parallel and identical in direction with each other; (b) disposing between the pair of substrates a chiral smectic liquid crystal capable of forming a higher-temperature alignment state and a lower-temperature alignment state in its chiral smectic phase; and (c) cooling the chiral smectic liquid crystal from a phase having a temperature higher than the chiral smectic phase to place the chiral smectic liquid crystal first in the higher-temperature alignment state and then further cooling the chiral smectic liquid crystal to place the liquid crystal in the lower-temperature alignment state in the chiral smectic phase in a bistable alignment state providing two stable orientation states.
Claim 3
Dependent Claim
55 words
A process according to claim 1, wherein said lower-temperature alignment state occurs at a temperature of at least 30° C. in the course of cooling the chiral smectic liquid crystal, wherein said further cooling step further comprises the step of further cooling the chiral smectic liquid crystal to a temperature of at least 30° C.
Claim 4
Dependent Claim
55 words
A process according to claim 1, wherein said lower-temperature alignment state occurs at a temperature of at least 40° C. in the course of cooling the chiral smectic liquid crystal, wherein said further cooling step further comprises the step of further cooling the chiral smectic liquid crystal to a temperature of at least 40° C.
Claim 5
Dependent Claim
120 words
A process for preparing a chiral smectic liquid crystal device, comprising the steps of: (a) providing a pair of substrates, each having a uniaxial alignment axis, said uniaxial alignment axes being parallel and identical in direction with each other; (b) disposing a chiral smectic liquid crystal between the pair of substrates; and (c) cooling the chiral smectic liquid crystal from a phase having a temperature higher than the chiral smectic phase to place the chiral smectic liquid crystal in a bistable first aligment state providing two stable orientation states in which a connected pair of a hairpin defect and a lightning defect are formed where the hairpin defect is formed after the lightning defect in the uniaxial alignment axis direction.
Claim 6
Dependent Claim
120 words
A process for preparing a chiral smectic liquid crystal device, comprising the steps of: (a) providing a pair of substrates, each having a uniaxial alignment axis, said uniaxial alignment axes being parallel and identical in direction with each other; (b) disposing a chiral smectic liquid crystal between the pair of substrates; and (c) cooling the chiral smectic liquid crystal from a phase having a temperature higher than the chiral smectic phase to place the chiral smectic liquid crystal in a bistable first aligment state providing two stable orientation states in which a connected pair of a hairpin defect and a lightning defect are formed where the hairpin defect is formed after the lightning defect in the uniaxial alignment axis direction.
Claim 7
Dependent Claim
72 words
A process according to claim 4, wherein said cooling step comprises the step of cooling the chiral smectic liquid crystal such that the first alignment state and another alignment state exist in the chiral smectic liquid crystal and wherein a first alignment state domain occupies a major proportion of the chiral smectic liquid crystal and a domain of the another alignment state occupies a minor proportion of the chiral smectic liquid crystal.
Claim 8
Dependent Claim
57 words
A process according to claim 5, wherein said cooling step further comprises the step of cooling the chiral smectic liquid crystal such that said first alignment state domain is grown to occupy a major proportion of the chiral smectic liquid crystal until said another alignment state occupies only a minor proportion of the chiral smectic liquid crystal.
Claim 9
Dependent Claim
101 words
A process according to claim 6, wherein the temperature range where said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal is 1/5 or less of the temperature range where said another alignment state domain occupies a minor proportion of the chiral smectic liquid crystal during cooling of the chiral smectic liquid crystal, wherein said cooling step further comprises the step of cooling the chiral smectic liquid crystal to a temperature at least five times the temperature at which said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal.
Claim 10
Dependent Claim
101 words
A process according to claim 6, wherein the temperature range where said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal is 1/10 or less of the temperature range where said another alignment state domain occupies a minor proportion of the chiral smectic liquid crystal during cooling of the chiral smectic liquid crystal, wherein said cooling step further comprises the step of cooling the chiral smectic liquid crystal to a temperature at least ten times the temperature at which said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal.
Claim 11
Dependent Claim
101 words
A process according to claim 6, wherein the temperature range where said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal is 1/20 or less of the temperature range where said another alignment state domain occupies a minor proportion of the chiral smectic liquid crystal during cooling of the chiral smectic liquid crystal, wherein said cooling step further comprises the step of cooling the chiral smectic liquid crystal to a temperature at least twenty times the temperature at which said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal.
Claim 12
Dependent Claim
57 words
A process according to claim 6, wherein said cooling step comprises the step of cooling the chiral smectic liquid crystal such that the lower limit of a temperature range where said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal is 30° C. during cooling of the chiral smectic liquid crystal.
Claim 13
Dependent Claim
55 words
A process according to claim 6, wherein said step comprises the step of cooling the chiral smectic liquid crystal such that lower limit of a temperature range where said another alignment state domain occupies not a minor proportion of the chiral smectic liquid crystal is 40° C. during cooling of the chiral smectic liquid crystal.
Claim 14
Dependent Claim
74 words
A process according to claim 5, wherein the providing and disposing steps form a liquid crystal cell comprising the pair of substrates and the chiral smectic liquid crystal, said method further comprising the steps of sealing the cell with a sealing member, forming the domain of said another alignment state in a neighborhood region of the sealing member of the cell, and forming the domain of said first alignment state inside the neighborhood region.
Claim 15
Dependent Claim
50 words
A process according to claim 5, further comprising the step of forming a connected pair of a hairpin defect and a lightning defect in the chiral smectic liquid crystal in said another alignment state, wherein the lightning defect is formed after the hairpin defect in the uniaxial alignment axis direction.
Claim 16
Dependent Claim
57 words
A process according to claim 4, wherein said cooling step further comprises the step of cooling the chiral smectic liquid crystal to place the chiral smectic liquid crystal in the bistable first alignment state such that the two stable orientation states in the domain in said first alignment state are optically equivalent, respectively, in an extinction position.
Claim 17
Dependent Claim
32 words
A process according to claim 4, further comprising the step of providing an alignment control film on one of the substrates and imparting a uniaxial alignment axis to the alignment control film.
Claim 18
Dependent Claim
22 words
A process according to claim 15, wherein said alignment control film comprises a polyimide film, a polyamide film, or a polyester film.
Claim 19
Dependent Claim
15 words
A process according to claim 15, wherein said alignment control film comprises a polyimide film.
Claim 20
Dependent Claim
30 words
A process according to claim 15, further comprising the step of providing an insulating film on one of the substrates and forming the alignment control film on the insulating film.
Claim 21
Dependent Claim
15 words
A process according to claim 4, wherein said uniaxial alignment axis is a rubbing axis.
Claim 22
Dependent Claim
141 words
A process for preparing a chiral smectic liquid crystal device, comprising the steps of: (a) providing a pair of substrates, each having a uniaxial alignment axis, said uniaxial alignment axes being parallel and identical in direction with each other; (b) disposing between the pair of substrate a chiral smectic liquid crystal assuming a chiral smectic phase and assuming a smectic A phase at a higher temperature than the chiral smectic phase; and (c) cooling the chiral smectic liquid crystal so that the chiral smectic liquid crystal first assumes the smectic A phase and then assumes the chiral smectic phase so that the liquid crystal molecules are aligned to form a pre-tilt angle of at least 2 degrees with respect to a substrate face at a temperature in the range in which the chiral smectic liquid crystal assumes the smectic A phase.
Claim 23
Dependent Claim
141 words
A process for preparing a chiral smectic liquid crystal device, comprising the steps of: (a) providing a pair of substrates, each having a uniaxial alignment axis, said uniaxial alignment axes being parallel and identical in direction with each other; (b) disposing between the pair of substrate a chiral smectic liquid crystal assuming a chiral smectic phase and assuming a smectic A phase at a higher temperature than the chiral smectic phase; and (c) cooling the chiral smectic liquid crystal so that the chiral smectic liquid crystal first assumes the smectic A phase and then assumes the chiral smectic phase so that the liquid crystal molecules are aligned to form a pre-tilt angle of at least 2 degrees with respect to a substrate face at a temperature in the range in which the chiral smectic liquid crystal assumes the smectic A phase.
Claim 24
Dependent Claim
15 words
A process according to claim 20, wherein said pre-tilt angle is at least 3 degrees.
Claim 25
Dependent Claim
32 words
A process according to claim 20, further comprising the step of providing an alignment control film on one of the substrates and imparting a uniaxial alignment axis to the alignment control film.
Claim 26
Dependent Claim
15 words
A process according to claim 22, wherein said alignment control film comprises a polyimide film.
Claim 27
Dependent Claim
30 words
A process according to claim 22, further comprising the step of providing an insulating film on one of the substrates and forming the alignment control film on the insulating film.
Claim 28
Dependent Claim
15 words
A process according to claim 20, wherein said uniaxial alignment axis is a rubbing axis.
References Cited (Backward Citations)
JPS643632A
Cited
US4932758A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1996-04-05 | 1996-10-05 | 1997-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-05 | 2000-10-05 | 2001-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-05 | 2004-10-05 | 2005-04-06 | $7700.00 | Window Closed / Lapsed |