Liquid crystal display device for color display

Abstract

The invention provides a liquid crystal display device for color display. The array substrate sequentially comprises a first substrate, a first conducting layer, a first orientation layer, a first guest-host liquid crystal composition layer, a second orientation layer, a second conducting layer, a second substrate, a third substrate, a third conducting layer, a third orientation layer, a second guest-host liquid crystal composition layer, a fourth orientation layer, a fourth conducting layer and a fourth substrate in the direction from light entering to light emitting. Wherein the components of the first guest-host liquid crystal composition layer and the second guest-host liquid crystal composition layer can be the same or different, each of the first guest-host liquid crystal composition layer and the second guest-host liquid crystal composition layer independently comprises at least one liquid crystal composition with positive dielectric anisotropy, at least one dichroic dye and at least one chiral agent, and the dichroic ratio of the dichroic dye is greater than 10. The liquid crystal display device can achieve display of different colors such as black, orange red, blue, red, cyan, yellow, purple and transparent, has a good display effect, and keeps a normally black state under the condition that driving voltage is not applied.

Description

Technical Field

[0001] This invention relates to a liquid crystal display device, and more specifically to a liquid crystal display device for color display. Background Technology

[0002] Liquid crystal displays (LCDs) have become the mainstream display technology of the 21st century. Compared with other display technologies, they are characterized by their thinness, low power consumption, and low driving voltage, making it easy to achieve effects such as lightweight and thin designs and large flat panel displays. LCD panels are passive devices that do not emit light themselves. Their working principle involves sandwiching a liquid crystal medium between two parallel glass substrates. Numerous fine vertical and horizontal wires exist within these substrates. By controlling the voltage, the alignment of the liquid crystal molecules can be changed, refracting the light emitted from the backlight module to produce the corresponding image. Currently, most liquid crystal elements used are mainly twisted nematic (TN) type, suitable for low line count driving, and super-twisted nematic (STN) type, suitable for high line count driving. However, because these elements use polarizing plates, they suffer from low light utilization efficiency.

[0003] Guest-host type liquid crystal display elements are a type of display element that can achieve high light utilization efficiency without a polarizer, especially in reflective display devices without a backlight, enabling luminescent display. Guest-host liquid crystals consist of a dichroic dye (guest) dissolved in a liquid crystal (host). The dye absorbs different wavelengths of visible light, causing the liquid crystal device to display different colors, thus achieving color display. Typically, dichroic dyes exhibit anisotropic absorption of visible light along their long and short axes. When the vibration direction of the incident light is aligned with the dye's long axis, the light is absorbed; when the vibration direction is perpendicular to the dye's long axis, the light can pass through. This allows the dye to exist in both absorbing and non-absorbing states during device operation. The dye molecules can align parallel to the liquid crystal molecules. When subjected to an electric field, the dye molecules change their orientation along with the liquid crystal molecules, thus altering the dye's absorption of visible light.

[0004] Chinese patent CN103744211A discloses a technical solution comprising three liquid crystal cells. This solution utilizes dichroic dyes to absorb some colors of light, thereby achieving color display. It eliminates the need for polarizers and color filters, reducing the manufacturing cost of the liquid crystal display panel to some extent, decreasing the requirements for backlight brightness, and improving light transmittance and luminous efficiency. However, the stacked use of three liquid crystal cells weakens the transmitted light to some extent, reducing luminous efficiency and increasing manufacturing costs. Furthermore, the dichroism of the dyes used is generally less than 10, and the solubility of dye molecules in the liquid crystal is generally less than 5%. This results in relatively high transmittance in the dark state and low contrast, failing to meet the current demands for high-contrast color displays.

[0005] Chinese patent CN103235445A discloses a reflective liquid crystal display device, which includes a dye liquid crystal composition layer. A reflective material is disposed between the dye liquid crystal composition layer and the lower substrate. The color of the dye in the liquid crystal composition and the color of the reflective material are complementary, which makes the reflective liquid crystal display device have higher reflectivity and higher contrast. It is also simple in structure and low in cost. However, this display mode can only realize the display of a single color, and the reflective brightness and transmittance cannot be adjusted, limiting its application scenarios.

[0006] In the application of liquid crystal display devices, contrast ratio is crucial to visual effects. Generally speaking, the higher the contrast ratio, the clearer and more striking the image, and the more vivid and vibrant the colors; conversely, if the contrast ratio is low, the entire image appears hazy and dull. High contrast ratio significantly improves image clarity, detail, and grayscale performance. High-contrast products have advantages in terms of black-and-white contrast, clarity, and image integrity. Contrast ratio also has a significant impact on the display effect of dynamic video. Because the transitions between light and dark in dynamic images are relatively rapid, the higher the contrast ratio, the easier it is for the human eye to distinguish these transitions.

[0007] Normal white mode and normal black mode are two commonly used display modes in LCD monitors. In normal white mode, the screen background is white, and text and images are black. In normal black mode, the screen background is black, and text and images are white. Normal black mode is more suitable for dark environments such as reading late at night or watching movies, as it reduces the eye strain from screen backlighting and improves viewing comfort. However, in normal black mode, the black background absorbs more light, so text and images may appear to "flicker" or blurry against the background, affecting the visual experience.

[0008] Therefore, how to obtain a liquid crystal display device with high contrast and constant black color display is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] Purpose of the Invention: The purpose of this invention is to provide a double-layer superimposed liquid crystal display device for color display, which can achieve different color changes in the visible light region (black, orange-red, blue, red, cyan, yellow, purple, and transparent, etc.) by driving voltage or selective dye mixing. It has low dark transmittance in the dark state and high bright transmittance in the bright state, that is, it can achieve multiple different color displays while having good display effect. Moreover, it maintains a constant black state when no driving voltage is applied, making it suitable for use in dark environments such as reading at night and watching movies.

[0010] Technical Solution: This invention provides a double-layer stacked liquid crystal display device for color display, comprising, from the direction of light entry to light exit, a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the components of the first host-guest liquid crystal composition layer and the second host-guest liquid crystal composition layer may be the same or different, and each independently contains at least one liquid crystal with positive dielectric anisotropy. The composition comprises a crystalline composition, at least one (e.g., two, three, or more) dichroic dye, and at least one (e.g., two, three, or more) chiral agent, wherein the dichroic ratio of the dichroic dye is greater than 10 (e.g., 10, 10.2, 10.4, 10.5, 10.6, 10.8, 11, 11.2, 11.4, 11.5, 11.6, 11.8, 12, 12.2, 12.4, 12.5, 12.6, 12.8, 13, 13.2, 13.4, 13.5, 13.6, 13.8, 1...). 4, 14.2, 14.4, 14.5, 14.6, 14.8, 15, 15.2, 15.4, 15.5, 15.6, 15.8, 16, 16.2, 16.4, 16.5, 16.6, 16.8, 17, 17.2, 17.4, 17.6, 17.8, 18, 18.2, 18.4, 18.6, 18.8, 19, 19.2, 19.4, 19.6, 19.8, 20, 20.2, 20.4, 20.6, 20.8, 21, 21.2, 21.4, 21.6, 21.8, 22, 22.2, 22.4, 22.6, 22.8, 23, 23.2, 23.4, 23.6, 23.8, 24, 24.2, 24.4, 24.6, 24.8, 25, 25.2, 25.4, 25.6, 25.8, 26, 26.2, 26.4, 26.6, 26.8, 27, 27.2, 27.4, 27.6, 27.8, 28, 28.2, 28.4, 28.6, 28.8, 29, 29.2, 29.4, 29.6, 29.8, 30).

[0011] In some embodiments of the present invention, the positive dielectric anisotropic liquid crystal composition comprises at least one compound of general formula A-1, general formula A-2 and / or a compound of general formula A-3:

[0012]

[0013]

[0014] in,

[0015] RA1 R A2 and R A3 Each of the following can independently represent -H, a straight-chain alkyl group containing 1-12 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms, or a branched alkyl group containing 3-12 (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) carbon atoms. One or more -CH2- groups of a straight-chain alkyl group containing 1-12 carbon atoms or a branched alkyl group containing 3-12 carbon atoms may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H groups of a straight-chain alkyl group containing 1-12 carbon atoms or a branched alkyl group containing 3-12 carbon atoms may be independently replaced by -F or -Cl;

[0016] ring ring ring and ring Each represents independently in One or more -CH2- bonds can be replaced by -O- bonds, and single bonds in one or at most two rings can be replaced by double bonds. One or more -H can be independently replaced by -F, -Cl or -CN, and -CH= in one or more rings can be replaced by -N=;

[0017] ring ring and ring Each represents independently or in One or more -CH2- bonds can be replaced by -O- bonds, and single bonds in one or at most two rings can be replaced by double bonds. One or more -H can be independently replaced by -F, -Cl, or an alkyl or alkoxy group containing 1-5 (e.g., 1, 2, 3, 4 or 5) carbon atoms, and -CH= in one or more rings can be replaced by -N=;

[0018] Z A11 Z A21 and Z A22 Each can independently represent a single bond, -CH2CH2-, -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -CH2O-, or -OCH2-;

[0019] Z A31 and ZA32 Each can independently represent a single bond, -CH2CH2-, -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -C≡C-, -N=N-, -CH2O-, or -OCH2-;

[0020] L A11 L A12 L A13 L A21 and L A22 Each can independently represent -H, an alkyl group containing 1-3 carbon atoms, or a halogen;

[0021] X A1 and X A2 Each can independently represent a halogen, a haloalkyl or haloalkoxy group containing 1-5 carbon atoms, or a haloalkenyl or haloalkenoxy group containing 2-5 carbon atoms.

[0022] X A3 Indicates -CN, -NCS, or NCS-;

[0023] n A11 Represents 0, 1, 2, or 3, when n A11 When = 2 or 3, the ring They can be the same or different, Z A11 They can be the same or different;

[0024] n A12 Represents 1 or 2, where when n A12 When = 2, ring They can be the same or different;

[0025] n A2 Represents 0, 1, 2, or 3, where when n A2 When = 2 or 3, the ring They can be the same or different, Z A21 They can be the same or different; and

[0026] n A31 and n A32 Each can independently represent 0, 1, or 2, when n A31 When = 2, ring They can be the same or different, Z A31 They can be the same or different, when n A32 When = 2, ring They can be the same or different.

[0027] In some embodiments of the invention, the compounds of general formula A-1, general formula A-2, and / or general formula A-3 constitute 0.1% to 80% by weight of the positive dielectric anisotropic liquid crystal composition (inclusive of any value or subrange within this range), for example 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%. %, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 43%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 73%, 74%, 75%, 76%, 78%, 80%, or a range between any two of these values.

[0028] In some embodiments of the present invention, the compounds of general formula A-1 are selected from the group consisting of the following compounds:

[0029]

[0030]

[0031]

[0032]

[0033] in,

[0034] R v and R w Each can be represented independently as -CH2- or -O-;

[0035] L A11 L A12 L A11 '、L A12 '、L A14 L A15 and L A16 Each can be represented independently as -H or -F;

[0036] L A13 and L A13 Each can be represented independently as -H or -CH3;

[0037] X A1 It indicates -F, -CF3, or -OCF3; and

[0038] v and w each independently represent 0 or 1.

[0039] In some embodiments of the present invention, the compounds of general formula A-1 are selected from the group consisting of the following compounds:

[0040]

[0041]

[0042] as well as

[0043]

[0044] In some embodiments of the invention, the compound of general formula A-1 accounts for 0.1% to 50% by weight of the positive dielectric anisotropic liquid crystal composition (inclusive of any value or subrange within this range), for example 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 41%, 42%, 44%, 46%, 48%, 50%, or a range between any two of these values.

[0045] In some embodiments of the invention, the weight percentage of the positive dielectric anisotropic liquid crystal composition is 0.1%-45% (inclusive of any value or subrange within this range), for example 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 3 5%, 36%, 38%, 40%, 41%, 42%, 44%, and 45% of compounds of general formula A-1 comprising at least one (e.g., two, three, four, or five) compounds selected from the group consisting of compounds of general formula A-1-1-1, general formula A-1-12-1, general formula A-1-17-2, general formula A-1-23-1, general formula A-1-23-2, and general formula A-1-25-1.

[0046] In some embodiments of the present invention, the compounds of general formula A-2 are selected from the group consisting of the following compounds:

[0047]

[0048]

[0049]

[0050]

[0051] in,

[0052] L A21 L A22 L A23 L A24 and L A25 Each can be independently represented as -H or -F; and

[0053] X A2 It represents -F, -CF3, -OCF3, or -CH2CH2CH=CF2.

[0054] In some embodiments of the present invention, the compounds of general formula A-2 are selected from the group consisting of the following compounds:

[0055]

[0056]

[0057] In some embodiments of the invention, the compound of general formula A-2 accounts for 0.1% to 50% by weight of the positive dielectric anisotropic liquid crystal composition (inclusive of any value or subrange within this range), for example 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, or a range between any two of these values.

[0058] In some embodiments of the invention, a compound of general formula A-2 comprising 1%-50% (e.g., 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%) of the positive dielectric anisotropic liquid crystal composition contains at least one (e.g., For example, compounds selected from the group consisting of two, three, four, five, six, seven, eight, or nine compounds of general formula A-2-5-2, general formula A-2-5-3, general formula A-2-7-1, general formula A-2-12-1, general formula A-2-12-2, general formula A-2-13-1, general formula A-2-13-2, general formula A-2-13-3, general formula A-2-20-1, and general formula A-2-20-2.

[0059] In some embodiments of the present invention, the compounds of general formula A-3 are selected from the group consisting of:

[0060]

[0061] as well as

[0062]

[0063] in,

[0064] L A31 L A32 L A34 and L A35 Each can be represented independently as -H or -F;

[0065] L A33 It represents -H, -F, -CH3, or -OCH3; and

[0066] Z A31 It represents -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -C≡C-, or -N=N-.

[0067] In some embodiments of the present invention, Z A31 It represents a single bond, -CO-O-, -O-CO-, or -O-CO-O-.

[0068] In some embodiments of the present invention, the compounds of general formula A-3 are selected from the group consisting of:

[0069]

[0070]

[0071] In some embodiments of the invention, the compound of general formula A-3 accounts for 0.1% to 40% by weight of the positive dielectric anisotropic liquid crystal composition (inclusive of any value or subrange within this range), for example 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 23%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, or a range between any two of these values.

[0072] In some embodiments of the present invention, the compound of general formula A-3 comprises at least one (e.g., two, three, four, five, six, seven, eight, or nine) compound selected from the group consisting of compounds of general formula A-3-1-4, compounds of general formula A-3-2-1, compounds of general formula A-3-4-1, compounds of general formula A-3-5-1, compounds of general formula A-3-5-2, and compounds of general formula A-3-13-1.

[0073] In some embodiments of the present invention, the positive dielectric anisotropic liquid crystal composition of the present invention further comprises at least one compound of general formula M:

[0074]

[0075] in,

[0076] R M1 and R M2 Each of these terms independently represents a straight-chain alkyl group containing 1 to 12 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12), or a branched alkyl group containing 3 to 12 carbon atoms (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12). One or more non-adjacent -CH2- in a straight-chain alkyl group containing 1-12 carbon atoms or a branched alkyl group containing 3-12 carbon atoms may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-;

[0077] ring ring and ring Each represents independently or in One or more -CH2- bonds can be replaced by -O- bonds, and single bonds in one or at most two rings can be replaced by double bonds. At most one -H in the halogen can be replaced by a halogen;

[0078] Z M1 and Z M2 Each can independently represent a single bond, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH=CH-, -CH2CH2-, or -(CH2)4-; and

[0079] n M Represents 0, 1, or 2, where when n M When = 2, ring They can be the same or different, Z M2 They can be the same or different.

[0080] In some embodiments of the present invention, the compounds of general formula M are selected from the group consisting of the following compounds:

[0081]

[0082]

[0083]

[0084]

[0085] as well as

[0086]

[0087] Among them, R M1 and R M2 Each can independently represent a straight-chain alkyl group containing 1-12 carbon atoms, a branched alkyl group containing 3-12 carbon atoms, or one or more non-adjacent -CH2- groups. -CH2- can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-.

[0088] In some embodiments of the invention, the compound of general formula M accounts for 0.1% to 60% by weight of the positive dielectric anisotropic liquid crystal composition (inclusive of any value or subrange within this range), for example 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%, 56%, 58%, 60%, or a range between any two of these values.

[0089] In some embodiments of the present invention, R M1 and R M2 Preferably, each is independently a straight-chain alkyl group containing 1-8 carbon atoms, a straight-chain alkoxy group containing 1-8 carbon atoms, or a straight-chain alkenyl group containing 2-8 carbon atoms; more preferably, each is independently a straight-chain alkyl group containing 1-5 carbon atoms, a straight-chain alkoxy group containing 1-5 carbon atoms, or a straight-chain alkenyl group containing 2-5 carbon atoms.

[0090] In some embodiments of the present invention, R M1 and R M2One of them is a straight-chain alkenyl group containing 2-5 carbon atoms, while the other is a straight-chain alkyl group containing 1-5 carbon atoms.

[0091] In some embodiments of the present invention, the compound of general formula M comprises at least one (e.g., two, three, four, five, or six) compound selected from the group consisting of compounds of general formula M-1, general formula M-5, general formula M-30, general formula M-39, general formula M-49, general formula M-51, and general formula M-57.

[0092] In some embodiments of the present invention, the compounds of general formula M are selected from the group consisting of the following compounds:

[0093]

[0094]

[0095] Among them, R M1 and R M2 Each is independently a straight-chain alkyl group containing 1-8 (e.g., 1, 2, 3, 4, 5, 6, 7, 8) carbon atoms;

[0096] R M2 'A straight-chain alkoxy group containing 1-7 (e.g., 1, 2, 3, 4, 5, 6, 7) carbon atoms; and

[0097] R M1 "and R M2 "Each is an alkenyl group with a straight chain containing 2-8 (e.g., 2, 3, 4, 5, 6, 7, 8) carbon atoms."

[0098] In some embodiments of the invention, the weight percentage of the positive dielectric anisotropic liquid crystal composition is 1%-58% (inclusive of any value or subrange within this range), for example 1%, 2%, 4%, 6%, 8%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 20%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 34%, 35%, 36%, 38%, 40%, 42%, 44%, 45%, 46%, 48%, 50%, 52%, 54%, 55%. The compounds of general formula M, comprising 56%, 58%, and 56%, contain at least one (e.g., two, three, four, five, or six) compounds selected from the group consisting of compounds of general formula M-1-1, general formula M-1-2, general formula M-1-3, general formula M-5-2, general formula M-22-2, general formula M-30-1, general formula M-30-3, general formula M-39-1, general formula M-49-1, general formula M-51-1, and general formula M-57-1.

[0099] In some embodiments of the present invention, the dichroic dye is selected from the group consisting of azo dichroic dyes, anthraquinone dichroic dyes, phthalocyanine dichroic dyes, cyanine dichroic dyes, indigo dichroic dyes, arylmethane dichroic dyes, nitro dichroic dyes, and nitroso dichroic dyes.

[0100] In some embodiments of the invention, the dichroic dye is selected from one or a combination of at least two (e.g., three, four, or five) compounds from the group consisting of:

[0101]

[0102]

[0103]

[0104] In some embodiments of the present invention, the amount of dichroic dye added is 0.01%-10% (inclusive of any value or subrange within this range) as a weight percentage of the host-guest liquid crystal composition layer, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.2%, 1.5%, 1.7%, 1.8%, 1.95%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.8%, 3%, 3.2%, ... 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or a range between any two of these values; preferably 0.2%-6%, more preferably 0.2%-4%.

[0105] In some embodiments of the present invention, the dichroic dye is selected from one or a combination of at least two of the following compounds:

[0106]

[0107]

[0108] In some embodiments of the present invention, the dichroic dyes in the first guest-host liquid crystal composition layer and the dichroic dyes in the second guest-host liquid crystal composition layer are complementary colors. When the dichroic dyes in the first guest-host liquid crystal composition layer and the dichroic dyes in the second guest-host liquid crystal composition layer are superimposed, they can absorb the entire visible light band and appear black.

[0109] In some embodiments of the present invention, the dichroic dye in the first guest-host liquid crystal composition layer is selected from the group consisting of dye 10, dye 14 and dye 15, and the dichroic dye in the second guest-host liquid crystal composition layer is selected from the group consisting of dye 3, dye 16 and dye 23.

[0110] In some embodiments of the present invention, the chiral agent of the present invention may be selected from any one or a combination of at least two of the following compounds:

[0111]

[0112]

[0113] as well as

[0114]

[0115] In this context, * indicates a chiral site.

[0116] In some embodiments of the present invention, the chiral agent constitutes 0.01%-10% (inclusive of any value or subrange within this range) of the weight percentage of the host-guest liquid crystal composition layer, for example, 0.01%, 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.7%, 1.8%, 2%, 2.1%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3%, 3.1%, 3.2%, 3.4%. 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8%, 6%, 6.2%, 6.4%, 6.6%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.4%, 8.6%, 8.8%, 9%, 9.2%, 9.4%, 9.6%, 9.8%, 10%, or a range between any two of these values.

[0117] In some embodiments of the present invention, the chiral agent is:

[0118]

[0119] In this context, * indicates a chiral site.

[0120] In some embodiments of the present invention, the chiral direction of the chiral agent in the first guest-host liquid crystal composition layer is opposite to that of the chiral direction of the second guest-host liquid crystal composition layer. For example, when the chiral agent in the first guest-host liquid crystal composition layer is S811, the chiral agent in the second guest-host liquid crystal composition layer is R811.

[0121] In some embodiments of the present invention, the first substrate, the second substrate, the third substrate and the fourth substrate are each independently glass or a rigid film layer, wherein the rigid film layer may be a transparent plastic film or a transparent plastic sheet.

[0122] In some embodiments of the present invention, the alignment direction between the first alignment layer and the second alignment layer is antiparallel alignment or parallel alignment, preferably antiparallel alignment.

[0123] In some embodiments of the present invention, the alignment direction between the third alignment layer and the fourth alignment layer is antiparallel alignment or parallel alignment, preferably antiparallel alignment.

[0124] In some embodiments of the present invention, the thickness of the first host-guest liquid crystal composition layer is 1 μm to 8 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm.

[0125] In some embodiments of the present invention, the thickness of the second host-guest liquid crystal composition layer is 1 μm to 8 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or 8 μm.

[0126] In some embodiments of the present invention, the thickness of the first guest-host liquid crystal composition layer and the thickness of the second guest-host liquid crystal composition layer may be the same or different. Preferably, the thickness of the first guest-host liquid crystal composition layer and the thickness of the second guest-host liquid crystal composition layer are the same.

[0127] In this invention, a host-guest liquid crystal composition containing a chiral agent is prepared by mixing a positive dielectric anisotropic liquid crystal composition, at least one (e.g., two or three) dichroic dyes and at least one (e.g., two or three) chiral agents in a weight ratio. Each of these components is independently filled into a first host-guest liquid crystal composition layer and a second host-guest liquid crystal composition layer to form a double-layer superimposed liquid crystal display device of this invention. When no driving voltage is applied to the liquid crystal display device (hereinafter referred to as the first layer display device) composed of the first substrate, the second substrate, and their intermediate layer, and the liquid crystal display device (hereinafter referred to as the second layer display device) composed of the third substrate, the fourth substrate, and their intermediate layer, the dual-layer superimposed liquid crystal display device of the present invention displays a dark state (i.e., black). When only the driving voltage is applied to the second layer display device and not to the first layer display device, the dual-layer superimposed liquid crystal display device of the present invention displays the color corresponding to the dye of the first host-guest liquid crystal composition layer. When only the driving voltage is applied to the first layer display device and not to the second layer display device, the dual-layer superimposed liquid crystal display device of the present invention displays the color corresponding to the dye of the second host-guest liquid crystal composition layer. When driving voltage is applied to both the first layer display device and the second layer display device simultaneously, the dual-layer superimposed liquid crystal display device of the present invention displays a bright state (i.e., white). Therefore, the dual-layer superimposed liquid crystal display device of the present invention can achieve the display of multiple colors, and when no power is applied, the dual-layer superimposed liquid crystal display device of the present invention displays a normally black state.

[0128] In addition to the compounds mentioned above, the liquid crystal compositions of the present invention may also contain common additives, such as antioxidants, ultraviolet absorbers, infrared absorbers, photoinitiators, polymerizable monomers, or light stabilizers.

[0129] Furthermore, the antioxidants, light stabilizers, and other additives used in the liquid crystal composition of the present invention are preferably the following substances:

[0130]

[0131]

[0132]

[0133]

[0134] Where n represents a positive integer from 1 to 12, n² represents a positive integer from 3 to 15, and + represents a free radical.

[0135] Preferably, the light stabilizer is selected from the compounds shown below:

[0136]

[0137] Where n represents a positive integer from 1 to 12.

[0138] In some embodiments of the present invention, the additive accounts for 0%-5% of the total weight percentage of the liquid crystal composition; preferably, the additive accounts for 0.01%-1% of the total weight percentage of the liquid crystal composition.

[0139] Beneficial effects: Compared with the prior art, the double-layer superimposed liquid crystal display device for color display of the present invention can achieve different color changes in the visible light region (e.g., black, orange-red, blue, red, cyan, yellow, purple, and transparent) by driving voltage or selective dye mixing. It has a low dark transmittance in the dark state and a high bright transmittance in the bright state. That is, it can achieve multiple different color displays while having a good display effect. Moreover, it maintains a constant black state without applying driving voltage, making it suitable for use in dark environments such as reading at night and watching movies. Detailed Implementation

[0140] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0141] Unless otherwise specified, the performance parameters of the embodiments and comparative examples in this invention were measured at room temperature.

[0142] For ease of explanation, the group structures of each compound in the following embodiments are represented by the codes listed in Table 1:

[0143] Table 1. Group structure codes of compounds

[0144]

[0145]

[0146] Take the following compound with the following structural formula as an example:

[0147]

[0148] If the structural formula is represented by the codes listed in Table 1, it can be expressed as: nCCGF, where n in the code represents the number of C atoms in the alkyl group at the left end. For example, if n is "3", it means that the alkyl group is -C3H7. In the code, C represents 1,4-cyclohexylene, G represents 2-fluoro-1,4-phenyleneene, and F represents fluorine substituent.

[0149] The abbreviated codes for the test items in the following examples are as follows:

[0150] Clearing point of Cp liquid crystal composition (nematic-isotropic phase transition temperature, °C)

[0151] Δn Optical anisotropy (589nm, 25℃)

[0152] Δε dielectric anisotropy (1kHz, 25℃)

[0153] CRmax contrast ratio (bright state transmittance / dark state transmittance, 25℃)

[0154] HTP liquid crystal spiral torsion force constant

[0155] T -40℃ Low-temperature storage stability (days, days) of liquid crystal compositions with positive dielectric anisotropy.

[0156] t -40℃ Low-temperature storage stability (days, d) of host-guest liquid crystal compositions containing chiral agents.

[0157] D dye dichroism

[0158] Tmax Bright state transmittance (%)

[0159] Tmin Dark-state transmittance (%)

[0160] in,

[0161] Cp: ​​Obtained by testing with a melting point apparatus.

[0162] Δn: Δn = n e -n o The results were obtained using an Abbe refractometer under a sodium lamp (589nm) light source at 25°C.

[0163] Δε: Δε=ε ∥ -ε ⊥ , where ε ∥ ε is the dielectric constant parallel to the molecular axis. ⊥ The dielectric constant is perpendicular to the molecular axis; test conditions: 25℃, 1KHz, antiparallel test box with a thickness of 7μm.

[0164] CRmax: The ratio of the maximum Tmax to Tmin.

[0165] HTP = 1 / (c × Pitch), where c is the chiral agent content and Pitch is the liquid crystal pitch value, obtained using a reading microscope, wedge box, and 25℃.

[0166] T -40℃ The time when crystal precipitation was observed was recorded when a liquid crystal composition with positive dielectric anisotropy was placed in a glass bottle and stored at a constant temperature of -40°C.

[0167] t -40℃ The host-guest liquid crystal composition containing a chiral agent was placed in a glass bottle and stored at a constant temperature of -40°C. The time when crystal precipitation was observed was recorded.

[0168] Tmax: The VT curve of the dimming device is tested using an LS182 optical transmittance meter. The maximum transmittance on the VT curve is taken as the transmittance of the liquid crystal. The test cell is a positive TN cell.

[0169] Tmin: The VT curve of the dimming device is tested using an LS182 optical transmittance meter. The minimum transmittance on the VT curve is taken as the transmittance of the liquid crystal. The test cell is a positive TN cell.

[0170] D: Dissolve the dichroic dye component at a weight percentage of 1% in the liquid crystal matrix, pour it into a 7μm positive-negative parallel rubbing cell, and use a liquid crystal photoelectric performance comprehensive tester to test the transmittance spectrum of the liquid crystal cell parallel to the polarizer and perpendicular to the polarizer. Select the point T where the parallel transmittance is lowest. ∥min and the vertical transmittance T at the corresponding wavelength ⊥min According to the formula A = Log(100 / T), A is calculated. ∥min and A ⊥min D = A ∥min / A ⊥min .

[0171] The components used in the following embodiments can be synthesized using methods known in the art or obtained commercially. These synthesis techniques are conventional, and the resulting liquid crystal compounds have been tested and found to meet electronic compound standards.

[0172] Liquid crystal compositions were prepared according to the proportions of the liquid crystal compounds specified in the following examples. The liquid crystal compositions were prepared according to conventional methods in the art, such as mixing in proportion by heating, ultrasound, suspension, etc.

[0173] LC1

[0174] A positive dielectric anisotropic liquid crystal composition LC1 was prepared according to the compounds and their weight percentages listed in Table 2, and was filled between two substrates of a liquid crystal display for performance testing.

[0175] Table 2. Formulation and performance parameter test results of liquid crystal composition LC1

[0176]

[0177] LC2

[0178] A positive dielectric anisotropic liquid crystal composition LC2 was prepared according to the compounds listed in Table 3 and their weight percentages, and was filled between two substrates of a liquid crystal display for performance testing.

[0179] Table 3. Formulation and performance parameter test results of liquid crystal composition LC2

[0180]

[0181] LC3

[0182] A positive dielectric anisotropic liquid crystal composition LC3 was prepared according to the compounds listed in Table 4 and their weight percentages, and was filled between two substrates of a liquid crystal display for performance testing.

[0183] Table 4. Formulation and performance parameter test results of liquid crystal composition LC3

[0184]

[0185] LC4

[0186] A positive dielectric anisotropic liquid crystal composition LC4 was prepared according to the compounds and their weight percentages listed in Table 5, and was filled between two substrates of a liquid crystal display for performance testing.

[0187] Table 5. Formulation and performance parameter test results of liquid crystal composition LC4

[0188]

[0189] LC5

[0190] A positive dielectric anisotropic liquid crystal composition LC5 was prepared according to the compounds and their weight percentages listed in Table 6, and was filled between two substrates of a liquid crystal display for performance testing.

[0191] Table 6. Formulation and performance parameter test results of liquid crystal composition LC5

[0192]

[0193]

[0194] LC6

[0195] A positive dielectric anisotropic liquid crystal composition LC6 was prepared according to the compounds and their weight percentages listed in Table 7, and was filled between two substrates of a liquid crystal display for performance testing.

[0196] Table 7. Formulation and performance parameter test results of liquid crystal composition LC6

[0197]

[0198] Example 1

[0199] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, sequentially includes a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component A in Table 1-1 is filled into the first host-guest liquid crystal composition layer (cell thickness is 4μm), and the liquid crystal composition of component B in Table 1-1 is filled into the second host-guest liquid crystal composition layer (cell thickness is 4μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0200] Table 1-1 Formulations of Liquid Crystal Compositions

[0201]

[0202] Wherein, dye 14 represents dye number 14, dye 15 represents dye number 15, and dye 23 represents dye number 23. In component A, the D value of dye 14 is 10.8, the D value of dye 15 is 11.5, and the D value of dye 23 in component B is 14.2.

[0203] The liquid crystal composition of component A has a twist angle of 480°, and the liquid crystal composition of component B has a twist angle of 480°.

[0204] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 1-2 below.

[0205] Table 1-2 Test Results of Liquid Crystal Display Device Performance Parameters

[0206]

[0207] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, orange-red, blue and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0208] Example 2

[0209] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, includes, in sequence, a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein, the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component C in Table 2-1 is filled into the first host-guest liquid crystal composition layer (cell thickness is 6μm), and the liquid crystal composition of component D in Table 2-1 is filled into the second host-guest liquid crystal composition layer (cell thickness is 6μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0210] Table 2-1 Formulation of Liquid Crystal Compositions

[0211]

[0212] Wherein, dye 14 represents dye number 14, dye 15 represents dye number 15, and dye 23 represents dye number 23. In component C, the D value of dye 14 is 10.8, the D value of dye 15 is 11.5, and the D value of dye 23 in component D is 14.2.

[0213] The liquid crystal composition of component C has a twist angle of 480°, and the liquid crystal composition of component D has a twist angle of 480°.

[0214] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 2-2 below.

[0215] Table 2-2 Test Results of Performance Parameters of Liquid Crystal Display Devices

[0216]

[0217] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, orange-red, blue and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0218] Example 3

[0219] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, includes, in sequence, a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein, the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component E in Table 3-1 is filled into the first host-guest liquid crystal composition layer (cell thickness is 4μm), and the liquid crystal composition of component F in Table 3-1 is filled into the second host-guest liquid crystal composition layer (cell thickness is 4μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0220] Table 3-1 Formulation of Liquid Crystal Compositions

[0221]

[0222] Wherein, dye 14 represents dye number 14, dye 16 represents dye number 16, and dye 23 represents dye number 23. In component E, the D value of dye 14 is 10.8, in component F, the D value of dye 23 is 14.2, and the D value of dye 16 is 13.6.

[0223] The liquid crystal composition of component E has a twist angle of 605°, and the liquid crystal composition of component F has a twist angle of 605°.

[0224] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 3-2 below.

[0225] Table 3-2 Test Results of Performance Parameters of Liquid Crystal Display Devices

[0226]

[0227] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, red, cyan and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0228] Example 4

[0229] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, sequentially includes a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component G in Table 4-1 is filled in the first host-guest liquid crystal composition layer (cell thickness is 7μm), and the liquid crystal composition of component H in Table 4-1 is filled in the second host-guest liquid crystal composition layer (cell thickness is 7μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0230] Table 4-1 Formulation of Liquid Crystal Compositions

[0231]

[0232] Wherein, dye 10 represents dye number 10, dye 3 represents dye number 3, and the D value of dye 10 in component G is 12.5, and the D value of dye 3 in component H is 15.6.

[0233] The liquid crystal composition of component G has a twist angle of 700°, and the liquid crystal composition of component H has a twist angle of 480°.

[0234] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 4-2 below.

[0235] Table 4-2 Test Results of Liquid Crystal Display Device Performance Parameters

[0236]

[0237] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, yellow, purple and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0238] Example 5

[0239] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, sequentially includes a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component I in Table 5-1 is filled into the first host-guest liquid crystal composition layer (cell thickness is 6μm), and the liquid crystal composition of component J in Table 5-1 is filled into the second host-guest liquid crystal composition layer (cell thickness is 6μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0240] Table 5-1 Formulation of Liquid Crystal Compositions

[0241]

[0242] Wherein, dye 14 represents dye number 14, dye 15 represents dye number 15, and dye 23 represents dye number 23. In component I, the D value of dye 14 is 10.8, the D value of dye 15 is 11.5, and the D value of dye 23 in component J is 14.2.

[0243] The liquid crystal composition of component I has a twist angle of 100°, and the liquid crystal composition of component J has a twist angle of 205°.

[0244] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 5-2 below.

[0245] Table 5-2 Test Results of Liquid Crystal Display Device Performance Parameters

[0246]

[0247] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, orange-red, blue and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0248] Example 6

[0249] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, sequentially includes a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component K in Table 6-1 is filled in the first host-guest liquid crystal composition layer (cell thickness is 4μm), and the liquid crystal composition of component L in Table 6-1 is filled in the second host-guest liquid crystal composition layer (cell thickness is 4μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0250] Table 6-1 Formulation of Liquid Crystal Compositions

[0251]

[0252] Wherein, dye 14 represents dye number 14, dye 16 represents dye number 16, and dye 23 represents dye number 23. In component K, the D value of dye 14 is 10.8, the D value of dye 23 in component L is 14.2, and the D value of dye 16 is 13.6.

[0253] The liquid crystal composition of component K has a twist angle of 480°, and the liquid crystal composition of component L has a twist angle of 605°.

[0254] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 6-2 below.

[0255] Table 6-2 Test Results of Performance Parameters of Liquid Crystal Display Devices

[0256]

[0257] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, red, cyan and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0258] Example 7

[0259] A color display device with a double-layer superimposed liquid crystal display, from the direction of light entry to light exit, sequentially includes a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the first alignment layer and the second alignment layer are antiparallel aligned, and the third alignment layer and the fourth alignment layer are antiparallel aligned. The liquid crystal composition of component Q in Table 7-1 is filled in the first host-guest liquid crystal composition layer (cell thickness is 9μm), and the liquid crystal composition of component R in Table 7-1 is filled in the second host-guest liquid crystal composition layer (cell thickness is 9μm). The first substrate, the second substrate, the third substrate, and the fourth substrate are ITO glass.

[0260] Table 7-1 Formulation of Liquid Crystal Compositions

[0261]

[0262] Wherein, dye 14 represents dye number 14, dye 15 represents dye number 15, and dye 23 represents dye number 23. In component Q, the D value of dye 14 is 10.8, the D value of dye 15 is 11.5, and the D value of dye 23 in component R is 14.2.

[0263] The liquid crystal composition of component Q has a twist angle of 100°, and the liquid crystal composition of component R has a twist angle of 205°.

[0264] The color display and related performance parameters of liquid crystal display devices under different power-on conditions are summarized in Table 7-2 below.

[0265] Table 7-2 Test Results of Performance Parameters of Liquid Crystal Display Devices

[0266]

[0267] As can be seen from the above performance parameter test data, the display device of the present invention can achieve a variety of different color changes such as black, orange-red, blue and transparent by adjusting whether or not a driving voltage is applied. It also has a low dark transmittance in the dark state and a high bright transmittance in the bright state, that is, it can achieve a variety of different color displays while also having a good display effect.

[0268] In summary, the double-layer superimposed liquid crystal display device of the present invention can achieve different color changes in the visible light region (e.g., black, orange-red, blue, red, cyan, yellow, purple, and transparent) by driving voltage or selective dyeing. It has a low dark transmittance in the dark state and a high bright transmittance in the bright state. That is, it can achieve the display of multiple different colors while having a good display effect. Moreover, it remains in a constant black state when no driving voltage is applied, making it suitable for use in dark environments such as reading at night and watching movies.

[0269] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A double-layer superimposed liquid crystal display device for color display, characterized in that, From the direction of light entry to light exit, the liquid crystal display device sequentially includes a first substrate, a first conductive layer, a first alignment layer, a first host-guest liquid crystal composition layer, a second alignment layer, a second conductive layer, a second substrate, a third substrate, a third conductive layer, a third alignment layer, a second host-guest liquid crystal composition layer, a fourth alignment layer, a fourth conductive layer, and a fourth substrate; wherein the components of the first host-guest liquid crystal composition layer and the second host-guest liquid crystal composition layer may be the same or different, and each independently contains at least one positive dielectric anisotropic liquid crystal composition, at least one dichroic dye, and at least one chiral agent, wherein the dichroic dye has a dichroic ratio greater than 10.

2. The liquid crystal display device according to claim 1, characterized in that, The positive dielectric anisotropic liquid crystal composition comprises at least one compound of general formula A-1, general formula A-2 and / or a compound of general formula A-3: in, R A1 R A2 and R A3 Each can be independently represented as -H, a straight-chain alkyl group containing 1-12 carbon atoms, or a branched alkyl group containing 3-12 carbon atoms. One or more of the -CH2- groups in the straight-chain alkyl group containing 1-12 carbon atoms or the branched alkyl group containing 3-12 carbon atoms may be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O- or -O-CO-, and one or more of the -H groups in the straight-chain alkyl group containing 1-12 carbon atoms or the branched alkyl group containing 3-12 carbon atoms may be independently replaced by -F or -Cl. ring ring ring and ring Each represents independently in One or more -CH2- bonds can be replaced by -O- bonds, and single bonds in one or at most two rings can be replaced by double bonds. One or more -H can be independently replaced by -F, -Cl or -CN, and -CH= in one or more rings can be replaced by -N=; ring ring and ring Each represents independently in One or more -CH2- bonds can be replaced by -O- bonds, and single bonds in one or at most two rings can be replaced by double bonds. One or more -H can be independently replaced by -F, -Cl, or an alkyl or alkoxy group containing 1-5 carbon atoms, and -CH= in one or more rings can be replaced by -N=; Z A11 Z A21 and Z A22 Each can independently represent a single bond, -CH2CH2-, -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -CH2O-, or -OCH2-; Z A31 and Z A32 Each can independently represent a single bond, -CH2CH2-, -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -C≡C-, -N=N-, -CH2O-, or -OCH2-; L A11 L A12 L A13 L A21 and L A22 Each can independently represent -H, an alkyl group containing 1-3 carbon atoms, or a halogen; X A1 and X A2 Each can independently represent a halogen, a haloalkyl or haloalkoxy group containing 1-5 carbon atoms, or a haloalkenyl or haloalkenoxy group containing 2-5 carbon atoms. X A3 Indicates -CN, -NCS, or NCS-; n A11 Represents 0, 1, 2, or 3, when n A11 When = 2 or 3, the ring They can be the same or different, Z A11 They can be the same or different; n A12 Represents 1 or 2, where when n A12 When = 2, ring They can be the same or different; n A2 Represents 0, 1, 2, or 3, where when n A2 When = 2 or 3, the ring They can be the same or different, Z A21 They can be the same or different; and n A31 and n A32 Each can independently represent 0, 1, or 2, when n A31 When = 2, ring They can be the same or different, Z A31 They can be the same or different, when n A32 When = 2, ring They can be the same or different; The compounds of general formula A-1, general formula A-2 and / or general formula A-3 account for 0.1% to 80% by weight of the positive dielectric anisotropic liquid crystal composition.

3. The liquid crystal display device according to claim 2, characterized in that, The compounds of general formula A-1 are selected from the group consisting of the following compounds: in, R v and R w Each can be represented independently as -CH2- or -O-; L A11 L A12 L A11 '、L A12 '、L A14 L A15 and L A16 Each can be represented independently as -H or -F; L A13 and L A13 Each can be represented independently as -H or -CH3; X A1 It indicates -F, -CF3, or -OCF3; and v and w each independently represent 0 or 1. The compounds of general formula A-2 are selected from the group consisting of the following compounds: as well as in, L A21 L A22 L A23 L A24 and L A25 Each can be represented independently as -H or -F; and X A2 This indicates -F, -CF3, -OCF3, or -CH2CH2CH=CF2; The compounds of general formula A-3 are selected from the group consisting of the following compounds: as well as in, L A31 L A32 L A34 and L A35 Each can be represented independently as -H or -F; L A33 It represents -H, -F, -CH3, or -OCH3; and Z A31 It represents -CF2CF2-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -CF=CF-, -C≡C-, or -N=N-.

4. The liquid crystal display device according to claim 1, characterized in that, The positive dielectric anisotropic liquid crystal composition further comprises at least one compound of general formula M: in, R M1 and R M2 Each can be independently represented as a straight-chain alkyl group containing 1-12 carbon atoms, or a branched alkyl group containing 3-12 carbon atoms. One or more of the straight-chain alkyl group containing 1-12 carbon atoms and the branched alkyl group containing 3-12 carbon atoms, or two or more non-adjacent -CH2-, can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-. ring ring and ring Each represents independently in One or more -CH2- bonds can be replaced by -O- bonds, and single bonds in one or at most two rings can be replaced by double bonds. At most one -H in the halogen can be replaced by a halogen; Z M1 and Z M2 Each can independently represent a single bond, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH=CH-, -CH2CH2-, or -(CH2)4-; and n M Represents 0, 1, or 2, where when n M When = 2, ring They can be the same or different, Z M2 They can be the same or different.

5. The liquid crystal display device according to claim 4, characterized in that, The compounds of general formula M are selected from the group consisting of the following compounds: as well as Among them, R M1 and R M2 Each of the following can independently represent a straight-chain alkyl group containing 1-12 carbon atoms or a branched alkyl group containing 3-12 carbon atoms. One or more of the straight-chain alkyl group containing 1-12 carbon atoms or the branched alkyl group containing 3-12 carbon atoms, or two or more of the -CH2- group, can be independently replaced by -CH=CH-, -C≡C-, -O-, -CO-, -CO-O-, or -O-CO-. The compound of general formula M accounts for 0.1%-60% by weight of the positive dielectric anisotropic liquid crystal composition.

6. The liquid crystal display device according to claim 1, characterized in that, The dichroic dyes are selected from the group consisting of azo dichroic dyes, anthraquinone dichroic dyes, phthalocyanine dichroic dyes, cyanine dichroic dyes, indigo dichroic dyes, arylmethane dichroic dyes, nitro dichroic dyes, and nitroso dichroic dyes. The amount of the dichroic dye added is 0.01%-10% of the weight percentage of the host-guest liquid crystal composition layer.

7. The liquid crystal display device according to claim 1, characterized in that, The chiral agent is selected from any one or a combination of at least two of the following compounds: as well as Where * indicates a chiral site; The chiral agent accounts for 0.01%-10% of the weight percentage of the host-guest liquid crystal composition layer.

8. The liquid crystal display device according to claim 1, characterized in that, The first substrate, the second substrate, the third substrate, and the fourth substrate are each independently glass or a rigid film layer, wherein the rigid film layer may be a transparent plastic film or a transparent plastic.

9. The liquid crystal display device according to claim 1, characterized in that, The alignment direction between the first alignment layer and the second alignment layer is either antiparallel alignment or parallel alignment; the alignment direction between the third alignment layer and the fourth alignment layer is either antiparallel alignment or parallel alignment.

10. The liquid crystal display device according to claim 1, characterized in that, The thickness of the first guest-host liquid crystal composition layer is 1μm to 8μm; the thickness of the second guest-host liquid crystal composition layer is 1μm to 8μm.

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