LIQUID CRYSTAL DIMMING DEVICE

Abstract

The present invention provides a liquid crystal dimming device. The liquid crystal dimming device of the present application sequentially comprises, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment; the guest-host liquid crystal composition layer comprises at least one dichroic dye, at least one chiral agent and at least one liquid crystal composition; wherein, the liquid crystal composition comprises at least one compound of general formula N. The liquid crystal dimming device of the present invention has an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. The dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Claims

1. A liquid crystal dimming device comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment; wherein the guest-host liquid crystal composition layer comprises at least one dichroic dye, at least one chiral agent and at least one liquid crystal composition; wherein, the liquid crystal composition comprises at least one compound of general formula N: ##STR00157## wherein, R.sub.N1 and R.sub.N2 each independently represents C.sub.1-12 linear or branched alkyl, ##STR00158## one or more than two nonadjacent CH.sub.2 in the C.sub.1-12 linear or branched alkyl can each be independently replaced by CHCH, CC, O, CO, COO or OCO; ring ##STR00159## and ring ##STR00160## each independently represents ##STR00161## wherein one or more CH.sub.2 in ##STR00162## can be replaced by O, one or more single bond in the rings can be replaced by double bond, wherein one or more H on ##STR00163## can each be independently substituted by F, Cl or CN, and one or more CH in the rings can be replaced by N; Z.sub.N1 and Z.sub.N2 each independently represents single bond, COO, OCO, CH.sub.2O, OCH.sub.2, CHCH, CC, CH.sub.2CH.sub.2, CF.sub.2CF.sub.2, (CH.sub.2).sub.4, CF.sub.2O or OCF.sub.2; L.sub.N1 and L.sub.N2 each independently represents H, halogen, C.sub.1-3 alkyl, or C.sub.1-3 alkoxy; and n.sub.N1 represents 0, 1, 2 or 3 n.sub.N2 represents 0 or 1, and 0n.sub.N1+n.sub.N23, when n.sub.N1=2 or 3, ring ##STR00164## can be the same or different, and Z.sub.N1 can be the same or different.

2. The liquid crystal dimming device according to claim 1, wherein the compound of general formula N is selected from a group consisting of the following compounds: ##STR00165## ##STR00166## ##STR00167## ##STR00168##

3. The liquid crystal dimming device according to claim 1, wherein the dielectric anisotropy of the liquid crystal component <0.

4. The liquid crystal dimming device according to claim 1, wherein the dichroic dye molecule is one or more dyes selected from the group consisting of dyes of azo type, anthraquinone type, phthalocyanine, cyanine type, indigoid, arylmethane, nitro and nitroso.

5. The liquid crystal dimming device according to claim 4, wherein the dichroic dye molecule is selected from the group consisting of the following compounds: ##STR00169## ##STR00170## ##STR00171## ##STR00172##

6. The liquid crystal dimming device according to claim 1, wherein the chiral agent is an S-type chiral compound or an R-type chiral compound.

7. The liquid crystal dimming device according to claim 6, wherein the S-type chiral compound is selected from a group consisting of the chiral agents of S1011, S2011, S5011, S811, S6N, and the R-type chiral compound is selected from a group consisting of the chiral agents of R1011, R2011, R5011, R811, R6N.

8. The liquid crystal dimming device according to claim 1, wherein the liquid crystal composition further comprises at least one compound of general formula M: ##STR00173## wherein, R.sub.M1 and R.sub.M2 each independently represents C.sub.1-12 linear or branched alkyl, ##STR00174## one or more than two nonadjacent CH.sub.2 in the C.sub.1-12 linear or branched alkyl can each be independently replaced by CHCH, CC, O, CO, COO or OCO; ring ##STR00175## ring ##STR00176## and ring ##STR00177## each independently represents ##STR00178## wherein one or more CH.sub.2 in ##STR00179## can be replaced by O, and one or more single bond in the rings can be replaced by double bond, at most one H on ##STR00180## can be substituted by halogen; Z.sub.M1 and Z.sub.M2 each independently represents single bond, COO, OCO, CH.sub.2O, OCH.sub.2, CC, CHCH, CH.sub.2CH.sub.2 or (CH.sub.2).sub.4; and n.sub.M represents 0, 1 or 2, wherein when n.sub.M=2, ring ##STR00181## can be the same or different, Z.sub.M2 can be same or different.

9. The liquid crystal dimming device according to claim 8, wherein the compound of general formula M is selected from a group consisting of the following compounds: ##STR00182## ##STR00183## ##STR00184##

10. The liquid crystal dimming device according to claim 8, wherein the compound of general formula N provides 0.1-98 wt. % of the liquid crystal composition, and the compound of general formula M provides 0.1-60 wt. % of the liquid crystal composition.

11. The liquid crystal dimming device according to claim 4, wherein the dichroic dye molecule is selected from the group consisting of dyes of azo type and anthraquinone type.

12. The liquid crystal dimming device according to claim 4, wherein the dichroic dye provides 0.01-10 wt. % of the total weight of the liquid crystal composition.

13. The liquid crystal dimming device according to claim 5, wherein the dichroic dye molecule is selected from a combination of one or at least two of the dye of the dye number of 5 to the dye of the dye number of 35.

14. The liquid crystal dimming device according to claim 13, wherein the dichroic dye molecule is selected from a combination of one or at least two of the dye of the dye number of 5 to the dye of the dye number of 22.

15. The liquid crystal dimming device according to claim 6, wherein the HTP value of the chiral compound is 5.

16. The liquid crystal dimming device according to claim 6, wherein the chiral compound provides 0.01-10 wt. % of the total weight of the liquid crystal composition.

17. The liquid crystal dimming device according to claim 7, wherein the chiral compound is selected from a group consisting of S1011, S2011, S811.

18. The liquid crystal dimming device according to claim 2, wherein the compound of general formula N is selected from compounds of a group consisting of the compound of general formula N-2, the compound of general formula N-5, the compound of general formula N-11.

19. The liquid crystal dimming device according to claim 9, wherein the compound of general formula M is selected from compounds of a group consisting of the compound of general formula M-1, the compound of general formula M-2, the compound of general formula M-12, the compound of general formula M-16, the compound of general formula M-26, the compound of general formula M-27, the compound of general formula M-28, the compound of general formula M-29, the compound of general formula M-30, the compound of general formula M-31, the compound of general formula M-32, and the compound of general formula M-33.

20. The liquid crystal dimming device according to claim 9, wherein the compound of general formula M comprises at least one compound selected from a group consisting of the compound of general formula M-26, the compound of general formula M-27, the compound of general formula M-28, the compound of general formula M-29, the compound of general formula M-30, the compound of general formula M-31, the compound of general formula M-32, and the compound of general formula M-33.

Description

DESCRIPTION OF DRAWINGS

[0173] FIG. 1 is the photograph of the surface of the liquid crystal dimming device in Example 1 at the moment of power-off after applying power on it for 2 h;

[0174] FIG. 2 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 1 at the moment of power-off after applying power on it for 2 h;

[0175] FIG. 3 is the photograph of the surface of the liquid crystal dimming device in Example 2 at the moment of power-off after applying power on it for 2 h;

[0176] FIG. 4 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 2 at the moment of power-off after applying power on it for 2 h;

[0177] FIG. 5 is the photograph of the surface of the liquid crystal dimming device in Example 3 at the moment of power-off after applying power on it for 2 h;

[0178] FIG. 6 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 3 at the moment of power-off after applying power on it for 2 h;

[0179] FIG. 7 is the photograph of the surface of the liquid crystal dimming device in Example 4 at the moment of power-off after applying power on it for 2 h;

[0180] FIG. 8 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 4 at the moment of power-off after applying power on it for 2 h;

[0181] FIG. 9 is the photograph of the surface of the liquid crystal dimming device in Example 5 at the moment of power-off after applying power on it for 2 h;

[0182] FIG. 10 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 5 at the moment of power-off after applying power on it for 2 h;

[0183] FIG. 11 is the photograph of the surface of the liquid crystal dimming device in Example 6 at the moment of power-off after applying power on it for 2 h;

[0184] FIG. 12 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 6 at the moment of power-off after applying power on it for 2 h;

[0185] FIG. 13 is the photograph of the surface of the liquid crystal dimming device in Example 7 at the moment of power-off after applying power on it for 2 h;

[0186] FIG. 14 is the photograph of the surface of the liquid crystal dimming device in Comparative Example 7 at the moment of power-off after applying power on it for 2 h.

DETAILED EMBODIMENTS

[0187] The technical solution of the present invention will be further illustrated by the detailed embodiments below. It should be clear for the person skilled in the art that, the Examples are only used to help to understand the present invention, and shall not be seen as specific limitations on the present invention.

[0188] The present invention will be illustrated by combining the detailed embodiments below. It should be noted that, the following Examples are instances of the present invention, which are only used to illustrate the present invention, not to limit it. Other combinations and various modifications within the conception of the present invention are possible without departing from the subject matter and scope of the present invention.

[0189] For the convenience of the expression, the group structures of the compounds in the following Examples are represented by the codes listed in Table 1:

TABLE-US-00002 TABLE 1 Codes of the group structures of the compounds Unit structure of group Code Name of group [00152] C 1,4-cyclohexylidene [00153] P 1,4-phenylene [00154] G 2-fluoro-1,4-phenylene [00155] W 2,3-difluoro- 1,4-phenylene COO E ester bridge group F F fluorine substituent O O oxygen bridge group CHCH or CHCH.sub.2 V ethenylene or ethenyl CH.sub.2O 1O methyleneoxy C.sub.nH.sub.2n+1 or C.sub.nH.sub.2n n (n alkyl or alkylene represents a positive integer of 1-12)

[0190] Take the compound with following structural formula as an example:

##STR00156##

[0191] represented by the codes listed in Table 1, this structural formula can be expressed as nCCGF, in which n in the code represents the number of the carbon atoms of the alkyl on the left, for example, n is 3, meaning that the alkyl is C.sub.3H.sub.7; C in the code represents 1,4-cyclohexylidene, G represents 2-fluoro-1,4-phenylene, and F represents fluorine.

[0192] The abbreviated codes of the test items in the following Examples are as follows: [0193] Cp clearing point (nematic-isotropy phases transition temperature, C.) [0194] n optical anisotropy (589 nm, 25 C.) [0195] dielectric anisotropy (1 KHz, 25 C.) [0196] T.sub.c phase transformation point in low temperature storage (i.e., the lower limit temperature of the nematic phase, C.) [0197] VHR (initial) initial voltage holding ratio (%) [0198] VHR (Ra) voltage holding ratio after maintained at a high temperature of 85 C. for 500 h (%) [0199] t.sub.30 C. low-temperature storage time (h, 30 C.) [0200] T.sub.r0 transmittance in an off-status (25 C., %) [0201] T.sub.r255 transmittance in an on-status (25 C., %) [0202] CR contrast rate (25 C.) [0203] wherein, [0204] Cp: tested by melting point apparatus. [0205] n: n=n.sub.en.sub.0, tested using an Abbe Refractometer under a sodium lamp (589 nm) light source at 25 C. [0206] : =.sub.|.sub., in which, .sub.| is the dielectric constant parallel to the molecular axis, .sub. is the dielectric constant perpendicular to the molecular axis, test conditions: 25 C., 1 KHz, VA-type test cell with a cell gap of 6 m. [0207] T.sub.c: placing the nematic phase liquid crystal materials in glass bottles and stored in refrigerators at temperatures of 0 C., 10 C., 20 C., 30 C., and 40 C., respectively, and then the low temperature at 10 days is observed, for example, if the sample is in the nematic phase at 20 C. and becomes crystalline or near-crystalline at 30 C., then the T.sub.c is <20 C. [0208] VHR (initial, 25 C.): initial voltage holding ratio, tested using a TOY06254 liquid crystal physical property evaluation system; the test temperature is 25 C., the test voltage is 5 V, and the test frequency is 6 Hz. [0209] VHR (initial, 60 C.): initial voltage holding ratio, tested using a TOY06254 liquid crystal physical property evaluation system; the test temperature is 60 C., the test voltage is 5 V, and the test frequency is 6 Hz. [0210] VHR (Ra, 25 C.): tested using a TOY06254 liquid crystal physical property evaluation system; the liquid crystal is tested after maintaining at a high temperature of 85 C. for 500 h; the test temperature is 25 C., the test voltage is 5 V, and the test frequency is 6 Hz. [0211] VHR (Ra, 60 C.): tested using a TOY06254 liquid crystal physical property evaluation system; the liquid crystal is tested after maintaining at a high temperature of 85 C. for 500 h; the test temperature is 60 C., the test voltage is 5 V, and the test frequency is 6 Hz. [0212] t.sub.30 C.: placing the nematic phase liquid crystal medium in glass bottles and stored at 30 C., the time recorded when precipitation of crystals was observed. [0213] CR: testing the transmittance (i.e., T.sub.r255 and T.sub.r0) of the liquid crystal cell using a DMS 505 tester at 255 gray-scale voltage and 0 gray-scale voltage respectively, and obtained from T.sub.r255/T.sub.r0.

[0214] The components used in the following Examples can either be synthesized by methods known in the art or be obtained commercially. The synthetic techniques are conventional, and each of the obtained liquid crystal compounds is tested to meet the standards of electronic compound.

[0215] The liquid crystal compositions are prepared in accordance with the ratios of each of the liquid crystal compounds specified in the following Examples. The preparation of the liquid crystal compositions is carried out according to the conventional methods in the art, such as mixed and prepared according to the ratios via means of heating, ultrasonic processing, suspending and so forth.

Example 1

[0216] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0217] The liquid crystal composition 1 is prepared according to each compound and weight percentage listed in Table 2, the dye providing 3.8 wt. % of the liquid crystal composition is added in the liquid crystal composition 1, the chiral agent S811 providing 1.14 wt. % of the liquid crystal composition is added in the liquid crystal composition 1, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 3.

TABLE-US-00003 TABLE 2 Formulation of liquid crystal composition Code of Weight Code of Performance component percent structure Parameters 3CWO2 15 N-2 Cp 111 5CWO2 10 N-2 n 0.106 3CWO4 15 N-2 6.6 2CPWO2 4 N-11 T.sub.c 30 3CPWO3 4 N-11 t.sub.30 C. 7 3CPWO4 4 N-11 3CCWO2 10 N-5 3CCWO3 10 N-5 4CCWO3 9 N-5 5CCWO2 9 N-5 3CCEPC2 5 M-30 3CCEPC5 5 M-30 Total 100

TABLE-US-00004 TABLE 3 Test results for the performance parameters T.sub.r0 12.6 T.sub.r255 57.2 CR 4.5 VHR (initial, 25 C.) 90.6 VHR (initial, 60 C.) 69.73 VHR (Ra, 25 C.) 73.75 VHR (Ra, 60 C.) 34.48

[0218] Applying power on the liquid crystal dimming device in Example 1 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 1.

Comparative Example 1

[0219] The difference between the present Comparative Example 1 and Example 1 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment. The performance test thereof is carried out and the results are shown in Table 4.

TABLE-US-00005 TABLE 4 Test results for the performance parameters T.sub.r0 12.4 T.sub.r255 57.5 CR 4.6 VHR (initial, 25 C.) 89.68 VHR (initial, 60 C.) 68.45 VHR (Ra, 25 C.) 51.53 VHR (Ra, 60 C.) 32.57

[0220] Applying power on the liquid crystal dimming device in Comparative Example 1 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 2.

[0221] It can be seen from the comparison between Comparative Example 1 and Example 1 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between FIG. 2 and FIG. 1 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 2

[0222] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0223] The liquid crystal composition 1 is prepared according to each compound and weight percentage listed in Table 2, the dye providing 3 wt. % of the liquid crystal composition is added in the liquid crystal composition 1, the chiral agent S811 providing 1.36 wt. % of the liquid crystal composition is added in the liquid crystal composition 1, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 5.

TABLE-US-00006 TABLE 5 Test results for the performance parameters T.sub.r0 16.8 T.sub.r255 58 CR 3.5 VHR (initial, 25 C.) 89.67 VHR (initial, 60 C.) 68.64 VHR (Ra, 25 C.) 70.54 VHR (Ra, 60 C.) 31.48

[0224] Applying power on the liquid crystal dimming device in Example 2 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 3.

Comparative Example 2

[0225] The difference between the present Comparative Example 2 and Example 2 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0226] The performance test thereof is carried out and the results are shown in Table 6.

TABLE-US-00007 TABLE 6 Test results for the performance parameters T.sub.r0 16.4 T.sub.r255 58.2 CR 3.5 VHR (initial, 25 C.) 88.33 VHR (initial, 60 C.) 66.21 VHR (Ra, 25 C.) 48.58 VHR (Ra, 60 C.) 28.94

[0227] Applying power on the liquid crystal dimming device in Comparative Example 2 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 4.

[0228] It can be seen from the comparison between Comparative Example 2 and Example 2 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between the FIG. 4 and FIG. 3 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 3

[0229] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0230] The liquid crystal composition 2 is prepared according to each compound and weight percentage listed in Table 7, the dye providing 4 wt. % of the liquid crystal composition is added in the liquid crystal composition 2, the chiral agent S811 providing 1.1 wt. % of the liquid crystal composition is added in the liquid crystal composition 2, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 8.

TABLE-US-00008 TABLE 7 Formulation of liquid crystal composition Code of Weight Code of Performance component percent structure Parameters 3CWO2 16.5 N-2 Cp 126 3CWO4 15 N-2 n 0.102 5CWO2 7 N-2 5.8 3CCWO2 10 N-5 T.sub.c 30 3CCWO3 10 N-5 t.sub.30 C. 7 4CCWO2 9 N-5 5CCWO2 9 N-5 2CPWO2 5.5 N-11 3CCEPC3 5 M-30 3CCEPC4 5 M-30 3CCEPC5 5 M-30 3CCEPC2 3 M-30 Total 100

TABLE-US-00009 TABLE 8 Test results for the performance parameters T.sub.r0 13.5 T.sub.r255 57 CR 4.2 VHR (initial, 25 C.) 90.75 VHR (initial, 60 C.) 68.76 VHR (Ra, 25 C.) 73.61 VHR (Ra, 60 C.) 33.4

[0231] Applying power on the liquid crystal dimming device in Example 3 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 5.

Comparative Example 3

[0232] The difference between the present Comparative Example 3 and Example 3 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0233] The performance test thereof is carried out and the results are shown in Table 9.

TABLE-US-00010 TABLE 9 Test results for the performance parameters T.sub.r0 13.6 T.sub.r255 57 CR 4.2 VHR (initial, 25 C.) 89.41 VHR (initial, 60 C.) 66.67 VHR (Ra, 25 C.) 51.22 VHR (Ra, 60 C.) 29.51

[0234] Applying power on the liquid crystal dimming device in Comparative Example 3 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 6.

[0235] It can be seen from the comparison between Comparative Example 3 and Example 3 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between the FIG. 6 and FIG. 5 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 4

[0236] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0237] The liquid crystal composition 2 is prepared according to each compound and weight percentage listed in Table 7, the dye providing 3.6 wt. % of the liquid crystal composition is added in the liquid crystal composition 2, the chiral agent S1011 providing 0.72 wt. % of the liquid crystal composition is added in the liquid crystal composition 2, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 10.

TABLE-US-00011 TABLE 10 Test results for the performance parameters T.sub.r0 13.2 T.sub.r255 53.4 CR 4 VHR (initial, 25 C.) 84.85 VHR (initial, 60 C.) 58.08 VHR (Ra, 25 C.) 62.88 VHR (Ra, 60 C.) 23.07

[0238] Applying power on the liquid crystal dimming device in Example 4 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 7.

Comparative Example 4

[0239] The difference between the present Comparative Example 4 and Example 4 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0240] The performance test thereof is carried out and the results are shown in Table 11.

TABLE-US-00012 TABLE 11 Test results for the performance parameters T.sub.r0 13.2 T.sub.r255 53.4 CR 4 VHR (initial, 25 C.) 83.52 VHR (initial, 60 C.) 56 VHR (Ra, 25 C.) 40.7 VHR (Ra, 60 C.) 19.22

[0241] Applying power on the liquid crystal dimming device in Comparative Example 4 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 8.

[0242] It can be seen from the comparison between Comparative Example 4 and Example 4 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between the FIG. 8 and FIG. 7 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 5

[0243] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0244] The liquid crystal composition 3 is prepared according to each compound and weight percentage listed in Table 12, the dye providing 3 wt. % of the liquid crystal composition is added in the liquid crystal composition 3, the chiral agent S811 providing 1.3 wt. % of the liquid crystal composition is added in the liquid crystal composition 3, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 13.

TABLE-US-00013 TABLE 12 Formulation of liquid crystal composition Code of Weight Code of Performance component percent structure Parameters 3CWO4 12 N-2 Cp 125 5CWO2 7 N-2 n 0.088 3CWO2 11.5 N-2 4.3 3CCWO3 7 N-5 T.sub.c 30 4CCWO2 7 N-5 t.sub.30 C. 7 5CCWO2 7 N-5 3CCWO2 7 N-5 3CC1OC5 3.5 M-24 VCCP1 2 M-12 3CCO3 5 M-1 3CGPC3 3 M-28 3CPO2 6 M-2 3CCEC5 3.5 M-21 4CCEC3 3.5 M-21 4CCECC3 3 M-31 3CCEPC3 4 M-30 3CCEPC4 4 M-30 3CCEPC5 4 M-30 Total 100

TABLE-US-00014 TABLE 13 Test results for the performance parameters T.sub.r0 21.4 T.sub.r255 64.2 CR 3 VHR (initial, 25 C.) 89.85 VHR (initial, 60 C.) 68.08 VHR (Ra, 25 C.) 72.88 VHR (Ra, 60 C.) 33.07

[0245] Applying power on the liquid crystal dimming device in Example 5 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 9.

Comparative Example 5

[0246] The difference between the present Comparative Example 5 and Example 5 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0247] The performance test thereof is carried out and the results are shown in Table 14.

TABLE-US-00015 TABLE 14 Test results for the performance parameters T.sub.r0 21.3 T.sub.r255 63.9 CR 3 VHR (initial, 25 C.) 88.12 VHR (initial, 60 C.) 65.98 VHR (Ra, 25 C.) 50.4 VHR (Ra, 60 C.) 29.22

[0248] Applying power on the liquid crystal dimming device in Comparative Example 5 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 10.

[0249] It can be seen from the comparison between Comparative Example 5 and Example 5 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between the FIG. 10 and FIG. 9 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 6

[0250] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0251] The liquid crystal composition 3 is prepared according to each compound and weight percentage listed in Table 12, the dye providing 3.8 wt. % of the liquid crystal composition is added in the liquid crystal composition 3, the chiral agent S1011 providing 1.25 wt. % of the liquid crystal composition is added in the liquid crystal composition 3, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 15.

TABLE-US-00016 TABLE 15 Test results for the performance parameters T.sub.r0 16.9 T.sub.r255 56.5 CR 3.3 VHR (initial, 25 C.) 84.5 VHR (initial, 60 C.) 55.4 VHR (Ra, 25 C.) 62.94 VHR (Ra, 60 C.) 23.36

[0252] Applying power on the liquid crystal dimming device in Example 6 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 11.

Comparative Example 6

[0253] The difference between the present Comparative Example 6 and Example 6 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0254] The performance test thereof is carried out and the results are shown in Table 16.

TABLE-US-00017 TABLE 16 Test results for the performance parameters T.sub.r0 16.6 T.sub.r255 56.4 CR 3.4 VHR (initial, 25 C.) 84.72 VHR (initial, 60 C.) 58.59 VHR (Ra, 25 C.) 42.51 VHR (Ra, 60 C.) 22.61

[0255] Applying power on the liquid crystal dimming device in Comparative Example 6 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 12.

[0256] It can be seen from the comparison between Comparative Example 6 and Example 6 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between the FIG. 12 and FIG. 11 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 7

[0257] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0258] The liquid crystal composition 3 is prepared according to each compound and weight percentage listed in Table 12, the dye providing 3.8 wt. % of the liquid crystal composition is added in the liquid crystal composition 3, the chiral agent S2011 providing 0.66 wt. % of the liquid crystal composition is added in the liquid crystal composition 3, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 17.

TABLE-US-00018 TABLE 17 Test results for the performance parameters T.sub.r0 18.5 T.sub.r255 59.4 CR 3.2 VHR (initial, 25 C.) 84.14 VHR (initial, 60 C.) 57.1 VHR (Ra, 25 C.) 65.04 VHR (Ra, 60 C.) 25.58

[0259] Applying power on the liquid crystal dimming device in Example 7 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 13.

Comparative Example 7

[0260] The difference between the present Comparative Example 6 and Example 6 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0261] The performance test thereof is carried out and the results are shown in Table 18.

TABLE-US-00019 TABLE 18 Test results for the performance parameters T.sub.r0 18 T.sub.r255 59.1 CR 3.3 VHR (initial, 25 C.) 83.03 VHR (initial, 60 C.) 59.97 VHR (Ra, 25 C.) 41.81 VHR (Ra, 60 C.) 19.74

[0262] Applying power on the liquid crystal dimming device in Comparative Example 7 for 2 h, the surface of the device at the moment of power-off is as shown in FIG. 14.

[0263] It can be seen from the comparison between Comparative Example 7 and Example 7 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. It can be seen from the comparison between the FIG. 14 and FIG. 13 that the dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

Example 8

[0264] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0265] The liquid crystal composition 4 is prepared according to each compound and weight percentage listed in Table 19, the dye providing 3.8 wt. % of the liquid crystal composition is added in the liquid crystal composition 4, the chiral agent S811 providing 1.14 wt. % of the liquid crystal composition is added in the liquid crystal composition 4, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 20.

TABLE-US-00020 TABLE 19 Formulation of liquid crystal composition Code of Weight Code of Performance component percent structure Parameters 3CWO2 15 N-2 Cp 96 5CWO2 10 N-2 n 0.102 3CWO4 15 N-2 6.5 2CPWO2 4 N-11 T.sub.c 30 3CPWO3 4 N-11 t.sub.30 C. 7 3CPWO4 4 N-11 3CPWO2 3 N-11 3CCWO2 9 N-5 3CCWO3 9 N-5 4CCWO3 9 N-5 5CCWO2 9 N-5 3CCEP5 5 M-22 3CCEC3 4 M-21 Total 100

TABLE-US-00021 TABLE 20 Test results for the performance parameters T.sub.r0 13.1 T.sub.r255 57.3 CR 4.4 VHR (initial, 25 C.) 89.61 VHR (initial, 60 C.) 67.33 VHR (Ra, 25 C.) 67.24 VHR (Ra, 60 C.) 14.28

Comparative Example 8

[0266] The difference between the present Comparative Example 8 and Example 8 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment. The performance test thereof is carried out and the results are shown in Table 21.

TABLE-US-00022 TABLE 21 Test results for the performance parameters T.sub.r0 13.4 T.sub.r255 57.2 CR 4.3 VHR (initial, 25 C.) 88.29 VHR (initial, 60 C.) 59.24 VHR (Ra, 25 C.) 42.14 VHR (Ra, 60 C.) 12.45

[0267] It can be seen from the comparison between Comparative Example 8 and Example 8 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range, and it can effectively avoid the problems of display mura and image sticking.

Example 9

[0268] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0269] The liquid crystal composition 4 is prepared according to each compound and weight percentage listed in Table 22, the dye providing 4 wt. % of the liquid crystal composition is added in the liquid crystal composition 4, the chiral agent S811 providing 1.1 wt. % of the liquid crystal composition is added in the liquid crystal composition 4, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 23.

TABLE-US-00023 TABLE 22 Formulation of liquid crystal composition Code of Weight Code of Performance component percent structure Parameters 3CWO2 12 N-2 Cp 124 3CWO4 12 N-2 n 0.103 5CWO2 12 N-2 5.8 3CCWO2 9 N-5 T.sub.c 30 3CCWO3 9 N-5 t.sub.30 C. 7 4CCWO2 9 N-5 5CCWO2 9 N-5 2CPWO2 5 N-11 3CPWO3 5 N-11 3CCEPC3 5 M-30 3CCEPC4 5 M-30 3CPCC2 5 M-32 3CGCC2 3 M-33 Total 100

TABLE-US-00024 TABLE 23 Test results for the performance parameters T.sub.r0 14.1 T.sub.r255 57.8 CR 4.1 VHR (initial, 25 C.) 89.43 VHR (initial, 60 C.) 67.34 VHR (Ra, 25 C.) 72.35 VHR (Ra, 60 C.) 33.5

Comparative Example 9

[0270] The difference between the present Comparative Example 9 and Example 9 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0271] The performance test thereof is carried out and the results are shown in Table 24.

TABLE-US-00025 TABLE 24 Test results for the performance parameters T.sub.r0 13.9 T.sub.r255 57.4 CR 4.1 VHR (initial, 25 C.) 88.66 VHR (initial, 60 C.) 67.23 VHR (Ra, 25 C.) 50.54 VHR (Ra, 60 C.) 28.54

[0272] It can be seen from the comparison between Comparative Example 9 and Example 9 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range.

Example 10

[0273] The present Example provides a liquid crystal dimming device, sequentially comprising, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; wherein alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment.

[0274] The liquid crystal composition 4 is prepared according to each compound and weight percentage listed in Table 7, the dye providing 3.6 wt. % of the liquid crystal composition is added in the liquid crystal composition 4, the chiral agent S1011 providing 0.72 wt. % of the liquid crystal composition is added in the liquid crystal composition 4, the performance test of the liquid crystal dimming device is carried out by filling the same into the guest-host liquid crystal composition layer of the present Example and the test results thereof are shown in Table 25.

TABLE-US-00026 TABLE 25 Test results for the performance parameters T.sub.r0 13.8 T.sub.r255 53.9 CR 3.9 VHR (initial, 25 C.) 84.25 VHR (initial, 60 C.) 57.08 VHR (Ra, 25 C.) 63.14 VHR (Ra, 60 C.) 23.14

Comparative Example 10

[0275] The difference between the present Comparative Example 10 and Example 10 merely lies in that the alignment directions of the upper alignment layer and the lower alignment layer are anti-parallel alignment.

[0276] The performance test thereof is carried out and the results are shown in Table 26.

TABLE-US-00027 TABLE 26 Test results for the performance parameters T.sub.r0 13.6 T.sub.r255 54.1 CR 4 VHR (initial, 25 C.) 83.68 VHR (initial, 60 C.) 52.36 VHR (Ra, 25 C.) 40.54 VHR (Ra, 60 C.) 18.65

[0277] It can be seen from the comparison between Comparative Example 10 and Example 10 that filling the liquid crystal composition with a higher clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy and a better low temperature storage stability, as well as the chiral agent and the dye into the liquid crystal dimming device of the present invention makes the liquid crystal dimming device of the present invention have an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range.

[0278] In conclusion, the liquid crystal dimming device of the present invention has an appropriate transmittance (T.sub.r0 is 12.6-21.4, T.sub.r255 is 53.4-64.2), an appropriate contrast rate (3-4.5), a higher VHR (initial) (VHR (initial, 25 C.) is above 84, VHR (initial, 60 C.) is above 55), a higher VHR (Ra) (VHR (Ra, 25 C.) is above 62, VHR (Ra, 60 C.) is above 14, even above 23) and a wider operation temperature range (the phase transformation point in low temperature storage 30 C.). The dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

[0279] The applicant declares that the liquid crystal dimming device of the present invention is illustrated by the above Examples, but the present invention is not limited to the above Examples, that is, it does not mean that the implement of the present application must rely on the above Examples. It shall be clear to the person skilled in the art that any improvements of the present invention, equivalent replacements of the raw materials used in the present invention, the additions of any auxiliary components, the selection of specific methods or the like all fall into the protection scope and the disclosure scope of the present invention.

INDUSTRIAL APPLICABILITY

[0280] The liquid crystal dimming device involved in the present invention can be applied to the construction and transportation fields.