Liquid crystal device

• US 6,001,276 A
• Filed: 07/18/1997
• Issued: 12/14/1999
• Est. Priority Date: 07/22/1996
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Nakamura, Shinichi, Terada, Masahiro, Sato, Koichi, Nakazawa, Ikuo, Asaoka, Masanobu, Takao, Hideaki
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US08/896,541
• Time in Patent Office: 879 Days
• Field of Search: 252/299.01, 252/299.4, 252/299.61, 252/299.62, 252/299.63, 252/299.6, 428/1.26, 349/122, 349/123, 349/124, 349/133, 349/184, 349/135
• US Class Current: 252/299.4
• CPC Class Codes: C09K 19/0225 Ferroelectric
• CPC Class Codes: C09K 2323/027 Polyimide
• CPC Class Codes: G02F 1/133723 Polyimide, polyamide-imide

Abstract

A liquid crystal device is constituted by a pair of transparent substrates each having thereon a transparent electrode, and a chiral smectic liquid crystal composition lacking cholesteric phase disposed between the substrates so as to assume at least two optically stable states. At least one of the substrates is provided with an alignment film which comprises a polyimide represented by a recurring unit of formula (I) shown below and has been subjected to a uniaxial aligning treatment. ##STR1## wherein A denotes a tetravalent aliphatic hydrocarbon group free from a planar structure or a tetravalent alicyclic hydrocarbon group, and n is an integer of at least 1. The chiral smectic liquid crystal composition may preferably contain at least one species of fluorine-containing mesomorphic compound comprising a fluorocarbon terminal portion and a hydrocarbon terminal portion connected with a central core and having a smectic phase or a latent smectic phase.

Claims

1. A liquid crystal device, comprising:

a pair of substrates each having thereon a transparent electrode, and a chiral smectic liquid crystal composition lacking cholesteric phase disposed between the substrates so as to assume at least two optically stable states,

wherein at least one of the substrates is provided with an alignment film which comprises a polyimide represented by a recurring unit of formula (I) shown below and has been subjected to a uniaxial aligning treatment, and

said chiral smectic liquid crystal composition has a layer spacing-changing characteristic providing a layer spacing d_A at a first transition point where the layer spacing of the liquid crystal composition begins to decrease at a discontinuously larger decrease rate on temperature decrease in vicinity of a transition temperature from smectic A phase to chiral smectic C phase and a layer spacing d_min at a second transition point where the layer spacing of the liquid crystal composition begins to increase on further temperature decrease from the first transition point, wherein 0.990≦

d_min /d_A, ##STR23## wherein A denotes a tetravalent aliphatic hydrocarbon group free from a planar structure or a tetravalent alicyclic hydrocarbon group, and n is an integer of at least 1.

2. A liquid crystal device according to claim 1, wherein n in the formula (I) is an even number of 2-10.

3. A liquid crystal device according to claim 1 or 2, wherein said chiral smectic liquid crystal composition has ferroelectricity.

4. A liquid crystal device according to any one of claims 1 to 3, wherein A in the formula (I) is ##STR24## .

5. A liquid crystal device according to claim 4, wherein A in the formula (I) is ##STR25## .

20. The liquid crystal device according to claim 1, wherein A denotes a tetravalent alicyclic hydrocarbon group.

21. The liquid crystal device according to claim 2, wherein A denotes a tetravalent alicyclic hydrocarbon group.

22. The liquid crystal device according to claim 3, wherein A denotes a tetravalent alicyclic hydrocarbon group.

23. The liquid crystal device according to claim 4, wherein A denotes a tetravalent alicyclic hydrocarbon group.

24. The liquid crystal device according to claim 5, wherein A denotes a tetravalent alicyclic hydrocarbon group.

6. A liquid crystal device, comprising:

a pair of substrates each having thereon a transparent electrode, and a chiral smectic liquid crystal composition disposed between the substrates so as to assume at least two optically stable states,

wherein at least one of the substrates is provided with an alignment film which comprises a polyimide represented by a recurring unit of formula (I) shown below and has been subjected to a uniaxial aligning treatment, and

said chiral smectic liquid crystal composition comprises at least one species of fluorine-containing mesomorphic compound comprising a fluorocarbon terminal portion and a hydrocarbon terminal portion connected with a central core and having a smectic phase or a latent smectic phase;

##STR26## wherein A denotes a tetravalent aliphatic hydrocarbon group free from a planar structure or a tetravalent alicyclic hydrocarbon group, and n is an integer of at least 1.

7. A liquid crystal device according to claim 6, wherein n in the formula (I) is an even number of 2-10.

8. A liquid crystal device according to claim 6 or 7, wherein said chiral smectic liquid crystal composition has ferroelectricity.

9. A liquid crystal device according to any one of claims 6 to 8, wherein A in the formula (I) is ##STR27## .

10. A liquid crystal device according to claim 9, wherein A in the formula (I) is ##STR28## .

11. A liquid crystal device according to claim 6, wherein said fluorocarbon terminal portion of the fluorine-containing mesomorphic compound is a group represented by the formula --D¹ --F_xa G_2xa --X, where xa is 1-20;

X is --H or --F;

--D¹ -- is --CO--O--(CH₂)_ra --, --O--(CH₂)_ra --, --(CH₂)_ra --, --O--SO₂ --, --SO₂ --, --SO₂ --(CH₂)_ra --, --O--(CH₂)_ra --O--(CH₂)_rb --, --(CH₂)_ra --N(C_pa H_2pa+1)--SO₂ -- or --(CH₂)_ra --N(C_pa H_2pa+1)--CO--;

where ra and rb are independently 1-20; and

pa is 0-4.

12. A liquid crystal device according to claim 6, wherein said fluorocarbon terminal portion of the fluorine-containing mesomorphic compound is a group represented by the formula --D² --(C_xb F_2xb --O)_za --C_ya F_2ya+1, where xb is 1-10 independently for each (C_xb F_2xb --O);

ya is 1-10;

za is 1-10;

--D² -- is --CO--O--C_rc H_2rc, --O--C_rc H_2rc --, --C_rc H_2rc --, --O--(C_sa H_2sa --O)_ta --C_rd H_2rd --, --O--SO₂ --, --SO₂ --, --SO₂ --C_rc H_2rc --, --C_rc H_2rc --N(C_pb H_2pb+1)--SO₂ --, --C_rc H_2rc --N(C_pb H_2pb+1)--CO--, or a covalent bond, where rc and rd are independently 1-20;

sa is independently 1-10 for each (C_sa H_2sa --O);

ta is 1-6; and

pb is 0-4.

13. A liquid crystal device according to claim 6, wherein said fluorine-containing mesomorphic compound is represented by the general formula (II):

##STR29## where A¹, A² and A³ are each independently ##STR30## ga, ha and ia are independently an integer of 0-3 with the proviso that the sum of ga+ha+ia be at least 2;

L¹ and L² are each independently a covalent bond, --CO--O--, --O--CO--, --COS--, --S--CO--, --CO--Se--, --Se--CO--, --CO--Te--, --Te--CO--, --CH₂ CH₂ --, --CH═

CH--, --C.tbd.C--, --CH═

N--, --N═

CH--, --CH₂ --O--, --O--CH₂ --, --CO-- or --O--;

X¹, Y¹ and Z¹ are each a substituent of A¹, A² and A³, respectively, and each of X¹, Y¹ and Z¹ are independently --H, --Cl, --F, --Br, --I, --OH, --OCH₃, --CH₃, --CN or --NO₂ ;

each ja, ma and na are independently an integer of 0-4;

J¹ is --CO--O--(CH₂)_ra --, --O--(CH₂)_ra --, --(CH₂)_ra --, --O--SO₂ --, --SO₂ --, --SO₂ --(CH₂)_ra --, --O--(CH₂)_ra --O--(CH₂)_rb --, --(CH₂)_ra --N(C_pa H_2pa+1)--SO₂ -- or --(CH₂)_ra --N(C_pa H_2pa+1)--CO--;

where ra and rb are independently 1-20, and pa is 0-4;

R¹ is --O--C_qa H_2qa --O--C_qb H_2qb+1, --C_qa H_2qa --O--C_qb H_2qb+1, --C_qa H_2qa --R³, --O--C_qa H_2qa --R³, --CO--O--C_qa H_2qa --R³, or --O--CO--C_qa H_2qa --R³ which may be either straight chain or branched;

where R³ is --O--CO--C_qb H_2qb+1, --CO--O--C_qb H_2qb+1, --H, --Cl, --F, --CF₃, --NO₂ or --CN; and

qa and qb are independently 1-20;

R² is C_xa F_2xa --X, where X is --H or --F, xa is an integer of 1-20.

14. A liquid crystal device according to claim 6, wherein said fluorine-containing mesomorphic compound is represented by the general formula (III):

##STR31## wherein A⁴, A⁵ and A⁶ are each independently ##STR32## gb, hb and ib are each independently an integer of 0-3 with the proviso that the sum of gb+hb+ib be at least 2;

each L³ and L⁴ are independently a covalent bond, --CO--O--, --O--CO--, --CO--S--, --S--CO--, --CO--Se--, --Se--CO--, --CO--Te--, --Te--CO--, --(CH₂ CH₂)_ka -- (ka is 1-4), --CH═

CH--, --C.tbd.C--, --CH═

N--, --N═

CH--, --CH₂ --O--, --O--CH₂ --, --CO-- or --O--;

X², Y² and Z² are each a substituent of A⁴, A⁵ and A⁶, respectively, and each X₂, Y₂ and Z₂ are independently --H, --Cl, --F, --Br, --I, --OH, --OCH₃,--CH₃, --CF₃, --O--CF₃, --CN or --NO₂ ;

each jb, mb and nb are independently an integer of 0-4;

J² is --CO--O--C_rc H_2rc --, --O--C_rc H_2rc --, --C_rc H_2rc --, --O(C_sa H_2sa --O)_ta --C_rd H_2rd --, --O--SO₂ --, --SO₂ --, --SO₂ --C_rc H_2rc --, --C_rc H_2rc --N(C_pb H_2pb+1)--SO₂ -- or --C_rc H_2rc --N(C_pb H_2pb+1)--CO--;

rc and rd are independently 1-20;

sa is independently 1-10 for each (C_sa H_2sa --O), ta is 1-6; and

pb is 0-4;

R⁴ is --O--(C_qc H_2qc --O)_wa --C_qd H_2qd+1, --(C_qc H_2qc --O)_wa --C_qd H_2qd+1, --C_qc H_2qc --R⁶, --O--C_qc H_2qc --R⁶, --CO--O--C_qc H_2qc --R⁶, or O--CO--C_qc H_2qc --R⁶ which may be either straight chain or branched;

R⁶ is --O--CO--C_qd H_2qd+1 ;

--CO--O--C_qd H_2qd+1, --Cl, --F, --CF₃, --NO₂, --CN or --H;

qc and qd are independently an integer of 1-20;

wa is an integer of 1-10;

R⁵ is (C_xb F_2xb --O)_za --C_ya F_2ya+1, wherein xb is independently 1-10 for each (C_xb F_2xb --O);

ya is 1-10; and

za is 1-10.

25. The liquid crystal device according to claim 6, wherein A denotes a tetravalent alicyclic hydrocarbon group.

26. The liquid crystal device according to claim 7, wherein A denotes a tetravalent alicyclic hydrocarbon group.

27. The liquid crystal device according to claim 8, wherein A denotes a tetravalent alicyclic hydrocarbon group.

28. The Liquid crystal device according to claim 9, wherein A denotes a tetravalent alicyclic hydrocarbon group.

29. The liquid crystal device according to claim 10, wherein A denotes a tetravalent alicyclic hydrocarbon group.

30. The liquid crystal device according to claim 11, wherein A denotes a tetravalent alicyclic hydrocarbon group.

31. The liquid crystal device according to claim 12, wherein A denotes a tetravalent alicyclic hydrocarbon group.

32. The liquid crystal device according to claim 13, wherein A denotes a tetravalent alicyclic hydrocarbon group.

33. The liquid crystal device according to claim 14, wherein A denotes a tetravalent alicyclic hydrocarbon group.

15. A liquid crystal device, comprising:

a pair of substrates each having thereon a transparent electrode, and a chiral smectic liquid crystal composition disposed between the substrates so as to assume at least two optically stable states,

wherein one of the substrates is provided with an alignment film which comprises a polyimide represented by a recurring unit of formula (I) shown below and has been subjected to a uniaxial aligning treatment, and

the other substrate is provided with an alignment film which has not been subjected to a uniaxial aligning treatment;

##STR33## wherein A denotes a tetravalent aliphatic hydrocarbon group free from a planar structure or a tetravalent alicyclic hydrocarbon group, and n is an integer of at least 1.

16. A liquid crystal device according to claim 15, wherein n in the formula (I) is an even number of 2-10.

17. A liquid crystal device according to claim 15 or 16, wherein said chiral smectic liquid crystal composition has ferroelectricity.

18. A liquid crystal device according to any one of claims 15 to 17, wherein A in the formula (I) is ##STR34## .

19. A liquid crystal device according to claim 18, wherein A in the formula (I) is ##STR35## .

34. The liquid crystal device according to claim 15, wherein A denotes a tetravalent alicyclic hydrocarbon group.

35. The liquid crystal device according to claim 16, wherein A denotes a tetravalent alicyclic hydrocarbon group.

36. The liquid crystal device according to claim 17, wherein A denotes a tetravalent alicyclic hydrocarbon group.

37. The liquid crystal device according to claim 18, wherein A denotes a tetravalent alicyclic hydrocarbon group.

38. The liquid crystal device according to claim 19, wherein A denotes a tetravalent alicyclic hydrocarbon group.