CN107300809B - Flexible liquid crystal display - Google Patents

Flexible liquid crystal display Download PDF

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Publication number
CN107300809B
CN107300809B CN201710541529.8A CN201710541529A CN107300809B CN 107300809 B CN107300809 B CN 107300809B CN 201710541529 A CN201710541529 A CN 201710541529A CN 107300809 B CN107300809 B CN 107300809B
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phase difference
thickness direction
liquid crystal
flexible substrate
flexible
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CN107300809A (en
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梁辉鸿
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Sumika Technology Co Ltd
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Sumika Technology Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/133305—Flexible substrates, e.g. plastics, organic film

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Liquid Crystal (AREA)
  • Polarising Elements (AREA)

Abstract

The embodiment of the invention relates to a flexible liquid crystal display, which comprises a liquid crystal layer; and a first flexible substrate and a second flexible substrate sandwiching (sandwich) the liquid crystal layer. The first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, and the sum of the phase difference value in the first thickness direction and the phase difference value in the second thickness direction is 20nm to 220 nm. The flexible liquid crystal display operates in an in-plane switching (IPS) mode or a Fringe Field Switching (FFS) mode.

Description

Flexible liquid crystal display
Technical Field
The present invention relates to a liquid crystal display, and more particularly, to a flexible liquid crystal display.
Background
As portable displays are widely used, the development of flexible displays is becoming more active. At present, flexible Organic Light Emitting Diode (OLED) displays are mainly developed for flexible displays, but the manufacturing cost is high.
On the other hand, the flexible lcd is also the subject of the development of manufacturers because the lcd is low in cost and has good moisture resistance. To achieve the "flexibility" requirement, a plastic substrate is generally used to replace the conventional glass substrate. However, whether the plastic substrate can be matched with the optical properties of the liquid crystal layer is also an important key to influence the display effect.
Therefore, how to match the optical characteristics of the liquid crystal and the plastic substrate to improve the overall optical performance is an important issue in the development of flexible liquid crystal displays.
Disclosure of Invention
An embodiment of the present invention provides a flexible liquid crystal display, including: a liquid crystal layer; and a first flexible substrate and a second flexible substrate sandwiching the liquid crystal layer. The first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, and the sum of the phase difference value in the first thickness direction and the phase difference value in the second thickness direction is 20nm to 220 nm. The flexible liquid crystal display operates in an in-plane switching (IPS) mode or a Fringe Field Switching (FFS) mode.
The embodiment of the invention also provides a flexible liquid crystal display, which comprises: a liquid crystal layer; a first flexible substrate and a second flexible substrate sandwiching the liquid crystal layer; and a first optical compensation film disposed on the first flexible substrate. The first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, the first optical compensation film has a phase difference value in a third thickness direction, and the sum of the phase difference value in the first thickness direction, the phase difference value in the second thickness direction and the phase difference value in the third thickness direction is 20nm to 220 nm. The flexible liquid crystal display operates in an in-plane switching (IPS) mode or a Fringe Field Switching (FFS) mode.
An embodiment of the present invention further provides a flexible liquid crystal display, including: a liquid crystal layer; a first flexible substrate and a second flexible substrate sandwiching the liquid crystal layer; the first optical compensation film is arranged on the first flexible substrate; and a second optical compensation film disposed on the second flexible substrate. The first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, the first optical compensation film has a phase difference value in a third thickness direction, the second optical compensation film has a phase difference value in a fourth thickness direction, and the sum of the phase difference value in the first thickness direction, the phase difference value in the second thickness direction, the phase difference value in the third thickness direction and the phase difference value in the fourth thickness direction is 20nm to 220 nm. The flexible liquid crystal display operates in an in-plane switching (IPS) mode or a Fringe Field Switching (FFS) mode.
Drawings
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various features are not drawn to scale and are merely illustrative. In fact, the dimensions of the elements may be arbitrarily expanded or reduced to clearly illustrate the features of the embodiments of the present invention.
FIG. 1 is a diagram illustrating the relationship between the sum of the phase difference values in the thickness direction of the film layers disposed on one side of the liquid crystal layer and the light leakage of the IPS/FFS LCD when the phase difference value (Delta _ nd) of the liquid crystal layer is 350nm according to some embodiments of the present invention;
FIG. 2 is a cross-sectional view of a flexible liquid crystal display 10 according to a first embodiment of the present invention;
FIG. 3 is a cross-sectional view of a flexible liquid crystal display 20 according to a second embodiment of the present invention;
FIG. 4 is a cross-sectional view of a flexible LCD 30 according to a third embodiment of the present invention;
FIG. 5A is a graph showing the light leakage at various viewing angles of an IPS/FFS LCD using a glass substrate;
FIG. 5B is a graph showing the leakage of light at various viewing angles of an IPS/FFS LCD using a polyimide substrate according to an embodiment of the present invention;
FIG. 6A is a graph showing the light leakage at each viewing angle of an IPS/FFS LCD using a glass substrate;
FIG. 6B is a graph showing the distribution of light leakage at various viewing angles of an IPS/FFS LCD using a polyimide substrate and an optical compensation film according to an embodiment of the present invention.
[ notation ] to show
10. 20, 30-flexible liquid crystal display
100-liquid crystal layer
100' -liquid crystal display unit
102-first flexible substrate
104-second flexible substrate
106 to first polarizing plate
108 to second polarizing plate
200-first optical compensation film
300 to the second optical compensation film
Detailed Description
While various embodiments or examples are disclosed below to practice various features of the invention, embodiments of specific elements and arrangements thereof are described below to illustrate the invention. These examples are, of course, intended to be illustrative only and should not be construed as limiting the scope of the invention. For example, references in the specification to a first element being formed on a second element include embodiments in which the first and second elements are in direct contact, and embodiments in which there are additional elements between the first and second elements, i.e., the first and second elements are not in direct contact. Moreover, where specific reference numerals or designations are used in various embodiments, these are merely used to identify the embodiments of the invention, and are not intended to identify particular relationships between the various embodiments and/or structures discussed.
Furthermore, spatially relative terms, such as "below," "lower," "above," "upper," and the like, may be used herein to describe one element or feature's relationship to another element or feature(s) of the illustrations and may encompass different orientations of the device in use or operation and orientations of the device in the figures and the like. The device may be turned to a different orientation (rotated 90 degrees or otherwise), and the spatially relative adjectives used herein may be similarly interpreted.
In addition, the terms of the optical properties of the embodiments of the present invention are defined as follows:
(1)nxis a refractive index in a direction in which an in-plane refractive index of the film layer is the largest (i.e., a slow axis direction), nyIs a refractive index in a direction perpendicular to a slow axis direction (i.e., a phase advancing axis direction) in a plane of the film layer, nzIs the refractive index in the thickness direction of the film layer, and d is the thickness of the film layer.
(2) The in-plane retardation R0 is defined as (n)x-ny) × d. generally, the in-plane phase difference of the film is measured using light having a wavelength of 590nm (nanometers).
(3) The phase difference value Rth in the thickness direction is defined as { [ (n)x+ny)/2]-nz× d. in general, the thickness direction phase difference is measured using light of wavelength 590 nm.
Generally, an In-Plane-Switching (IPS) liquid crystal display panel includes a pair of substrates and a liquid crystal layer disposed between the substrates, and liquid crystal molecules In the liquid crystal layer are aligned parallel to the substrates. One of the substrates is a transistor array substrate and comprises a plurality of pixel electrodes and common voltage electrodes, wherein the pixel electrodes and the common voltage electrodes are positioned on a common plane and are arranged in a crossed manner. In addition, a Fringe-Field Switching (FFS) lcd panel also includes a pair of substrates and a liquid crystal layer disposed between the substrates, and liquid crystal molecules in the liquid crystal layer are aligned parallel to the substrates. Unlike IPS, the pixel electrode and the common electrode in the transistor array substrate of FFS do not lie on the same plane. Although the IPS and FFS structures are slightly different, the modes of operation are very similar. When a corresponding signal is given to the pixel electrode, the pixel electrode and the common electrode form an electric field, and the liquid crystal molecules can be driven by the electric field to horizontally twist (parallel to the substrate) so that part of light can pass through the liquid crystal plane. Since the liquid crystal molecules are horizontally twisted, the IPS or FFS liquid crystal display panel can obtain a better viewing angle (for example, a viewing angle of 178 degrees in the vertical direction, the horizontal direction, and the vertical direction). However, since the liquid crystal molecules of the IPS/FFS liquid crystal display panel are horizontally aligned, the transmittance of light is also poor. The luminance of the backlight is increased to better display the bright color, and the problem of light leakage is caused, so that the contrast of the IPS/FFS liquid crystal display panel is poor.
Accordingly, the present invention provides a structure for an IPS/FFS mode LCD, especially a flexible LCD, which has good viewing angle, low light leakage and high contrast.
Referring to FIG. 1, according to some embodiments of the present invention, a relationship between a sum of phase differences in a thickness direction of a film layer disposed on one side of a liquid crystal layer and a light leakage amount of an IPS/FFS liquid crystal display when a phase difference (Delta _ nd) of the liquid crystal layer is 350nm is illustrated. As is clear from fig. 1, the FFS/IPS display has better optical performance when the sum of the phase difference values in the thickness direction of the film layer disposed on one side of the liquid crystal layer is 10nm to 110nm (preferably 40nm to 80 nm). In other words, if the sum of the phase difference values in the thickness direction of the film layers disposed on the liquid crystal layer side can be controlled to be 10nm to 110nm (preferably 40nm to 80nm), the light leakage amount of the FFS/IPS display can be controlled to be 0.006% or less (preferably 0.005% or less, more preferably 0.004% or less), and thus the contrast of the FFS/IPS display at each viewing angle can be improved.
[ first embodiment ] A method for manufacturing a semiconductor device
In this embodiment, the phase difference between the flexible substrate and the liquid crystal layer is matched according to the result shown in fig. 1, so that the flexible liquid crystal display has good optical performance.
Referring to fig. 2, a flexible liquid crystal display 10 of the present embodiment is shown, which includes a liquid crystal display unit 100 ', a first polarizing plate 106 and a second polarizing plate 108, wherein the liquid crystal display unit 100' includes a liquid crystal layer 100, a first flexible substrate 102 and a second flexible substrate 104. In the present embodiment, the flexible liquid crystal display 10 operates in an IPS mode or an FFS mode. In other words, liquid crystal molecules in the liquid crystal layer 100 are horizontally aligned with the first flexible substrate 102 and the second flexible substrate 104, and the pixel electrode and the common voltage electrode (not shown in the drawings) are located on the same side of the liquid crystal layer 100 (i.e., the pixel electrode and the common voltage electrode are located on the first flexible substrate 102 or the second flexible substrate 104).
In some embodiments, the phase difference value (Delta _ nd) of the liquid crystal layer 100 may be 310nm to 370nm, wherein the refractive index difference Δ n of the liquid crystal layer 100 may be between about 0.09 and 0.12.
Referring to fig. 2, a liquid crystal layer 100 is sandwiched between a first flexible substrate 102 and a second flexible substrate 104. In some embodiments, the first flexible substrate 102 and the second flexible substrate 104 are in direct contact with the liquid crystal layer 100.
For example, the first flexible substrate 102 may be an active matrix substrate provided with switching elements (e.g., thin film transistors) for controlling electro-optical characteristics of liquid crystal, and scanning lines for supplying gate signals and signal lines for supplying source signals to the switching elements, and the second flexible substrate 104 may be a color filter substrate provided with color filters. However, the color filter may be disposed on the active matrix substrate.
For example, the first flexible substrate 102 and the second flexible substrate 104 may be formed of Polyimide (PI), which is different from a conventional glass substrate, and the polyimide substrate has an optical anisotropic property due to the influence of a polymer structure and process conditions, thereby generating an optical retardation valueTherefore, when used with a liquid crystal layer, the optical properties of the liquid crystal layer must be considered to match with those of the liquid crystal layer to obtain better optical performance. For example, each of the substrates 102 and 104 formed of polyimide may have an appropriate optical anisotropy, such as nx＝ny>nz. In addition, the visible light transmittances of the first flexible substrate 102 and the second flexible substrate 104 may be respectively greater than 90% (e.g., 90.99% to 99.99%). In addition, the substrates 102 and 104 formed of polyimide have flexibility characteristics, which can meet the requirement of the flexible lcd 10. For example, polyimide material may be coated on a substrate such as glass, and then the substrate may be taken down as the first flexible substrate 102 and the second flexible substrate 104 after film formation.
According to the results shown in FIG. 1, the first flexible substrate 102 has a first thickness direction phase difference R1, the second flexible substrate 104 has a second thickness direction phase difference R2, and the sum of the first thickness direction phase difference and the second thickness direction phase difference R1+ R2 is 20nm to 220nm, preferably 80nm to 160nm, for the liquid crystal layer 100 with the phase difference of 310nm to 370nm, so that the flexible liquid crystal display 10 has a lower light leakage and better optical performance (e.g., high contrast). In some embodiments, the in-plane phase difference of the first flexible substrate 102 and the second flexible substrate 104 may be 0 nm. In some embodiments, at least one of the first flexible substrate 102 and the second flexible substrate 104 may have a thickness of 1 μm to 25 μm, preferably 5 μm to 20 μm, so that at least one of the first thickness direction phase difference R1 and the second thickness direction phase difference R2 is controlled to be 10nm to 110nm, preferably 40nm to 80 nm. It should be noted that the first thickness direction difference R1 and the second thickness direction difference R2 may be the same or different. Therefore, the light leakage of the flexible lcd 10 operating in the IPS mode or the FFS mode can be controlled to be less than 0.006% (preferably less than 0.005%, more preferably less than 0.004%), so as to improve the contrast at each viewing angle.
Referring to fig. 5A and 5B, the light leakage amount at each viewing angle of the IPS/FFS liquid crystal display using the glass substrate and the IPS/FFS liquid crystal display using the polyimide substrate of the present embodiment (for example, R1+ R2 is 120nm) is respectively shown, where the block R represents a portion where the light leakage amount is large (the light leakage amount is greater than 0.006%), and the LV represents the maximum light leakage amount in the entire region. As can be clearly seen from fig. 5A and 5B, when the total of the first thickness direction phase difference R1 of the first flexible substrate 102 and the second thickness direction phase difference R2 of the second flexible substrate 104, R1+ R2, is 120nm, the light leakage amount at each viewing angle is significantly reduced, compared to the liquid crystal display of glass substrate, wherein the maximum light leakage amount in the whole area is reduced from 0.0071% to 0.0045%.
Referring to fig. 2, the first polarizer 106 and the second polarizer 108 sandwich the first flexible substrate 102, the second flexible substrate 104 and the liquid crystal layer 100. In some embodiments, the first polarizer 106 is in direct contact with the first flexible substrate 102 and the second polarizer 108 is in direct contact with the second flexible substrate 104 without any other film therebetween. The first polarizing plate 106 and the second polarizing plate 108 may have appropriate thicknesses, respectively. Each of the first polarizing plate 106 and the second polarizing plate 108 may include a hydrophilic polymer film uniaxially stretched after absorbing iodine or a dichroic dye, for example: polyvinyl alcohol-based films, partially dimethoxymethanated polyvinyl alcohol-based films, ethylene-vinyl acetate copolymer-based partially saponified films, combinations of the above, or other suitable materials.
In summary, in the present embodiment, the first flexible substrate 102 and the second flexible substrate 104 have appropriate phase difference in the thickness direction (for example, the sum of the phase difference in the thickness direction of the two is 20nm to 220nm, preferably 80nm to 160nm), so that the first flexible substrate and the second flexible substrate can have better optical performance when used in combination with the liquid crystal layer 100 having a phase difference of 310nm to 370 nm.
[ second embodiment ]
Referring to fig. 3, a difference between the flexible liquid crystal display 20 of the present embodiment and the flexible liquid crystal display 10 of the first embodiment is that a first optical compensation film 200 is further disposed between the first flexible substrate 102 and the first polarizer 106 of the flexible liquid crystal display 20. In addition, the flexible liquid crystal display 20 is properly matched with the phase difference values of the optical compensation film 200, the first flexible substrate 102, the second flexible substrate 104 and the liquid crystal layer, so as to have good optical performance.
The first optical compensation film 200 may have a suitable optical anisotropy, such as nx＝ny<nzAnd can be optically anisotropic (n) with respect to the first substrate 102 and the second substrate 104x＝ny>nz) The phase difference in the thickness direction is properly obtained by matching the two layers, so that the flexibility of the film design can be increased. In the present embodiment, the first flexible substrate 102 has a first thickness direction phase difference R1, the second flexible substrate 104 has a second thickness direction phase difference R2, and the first optical compensation film 200 has a third thickness direction phase difference R3. For example, the third thickness direction phase difference R3 may be 0 to-500 nm. In order to match the liquid crystal layer 100 with the phase difference of 310nm to 370nm, the sum of the first thickness direction phase difference R1, the second thickness direction phase difference R2 and the third thickness direction phase difference R3, i.e., R1+ R2+ R3, may be 20nm to 220nm, preferably 80nm to 160nm, so that the flexible liquid crystal display 20 has a lower light leakage and better optical performance (e.g., high contrast).
For example, at least one of the sum of the first thickness direction phase difference and the third thickness direction phase difference R1+ R3 and the second thickness direction phase difference R2 is 10nm to 110nm, preferably 40nm to 80 nm. It should be noted that the sum of the first thickness direction phase difference value and the third thickness direction phase difference value R1+ R3 and the second thickness direction phase difference value R2 may be the same or different. Therefore, the light leakage of the flexible lcd 20 operating in the IPS mode or the FFS mode can be controlled to be less than 0.006% (preferably less than 0.005%, more preferably less than 0.004%), so as to improve the contrast at each viewing angle.
The thickness of the first optical compensation film 200 may be 0.1 to 50 μm, preferably 1 to 20 μm, whereby the third thickness direction phase difference R3 is controlled to be 0nm to-500 nm. For example, the first optical compensation film 200 may be formed of polyamide, polyimide, polyester, polyether ketone, polyamide-imide, polyester-imide, combinations thereof, or other suitable materials. For example, the first optical compensation film 200 may be formed by liquid crystal coating or other suitable methods, and in some embodiments, the first optical compensation film 200 may be formed by liquid crystal coating, and may be in the form of discotic liquid crystal.
In some embodiments, the first optical compensation film 200 may be in direct contact with the first flexible substrate 102 and/or the first polarizer 106 without any other film therebetween. In addition, although the first optical compensation film 200 is a single film in the embodiment, if the above-mentioned condition related to the phase difference value can be satisfied, in some other embodiments, the first optical compensation film 200 may also include a plurality of sub-layers.
[ third embodiment ]
Referring to fig. 4, a difference between the flexible liquid crystal display 30 of the present embodiment and the flexible liquid crystal display 20 of the second embodiment is that a second optical compensation film 300 is disposed between the second flexible substrate 104 and the second polarizer 108 of the flexible liquid crystal display 30. The second optical compensation film 300 may include the same or similar properties as the first optical compensation film 200.
The second optical compensation film 300 can have a suitable optical anisotropy, such as nx＝ny<nzAnd the first substrate 102, the second substrate 104 and the first optical compensation film 200 can be matched with each other to obtain a proper sum of phase differences in the thickness direction, so that the flexibility of film design can be increased.
In the present embodiment, the first flexible substrate 102 has a first thickness direction phase difference R1, the second flexible substrate 104 has a second thickness direction phase difference R2, the first optical compensation film 200 has a third thickness direction phase difference R3, and the second optical compensation film 300 has a fourth thickness direction phase difference R4. For example, at least one of the third thickness direction phase difference R3 and the fourth thickness direction phase difference R4 may be 0 to-500 nm. In order to match the liquid crystal layer 100 with the phase difference of 310nm to 370nm, the sum of the phase difference in the first thickness direction, the phase difference in the second thickness direction, the phase difference in the third thickness direction and the phase difference in the fourth thickness direction, R1+ R2+ R3+ R4, may be 20nm to 220nm, preferably 80nm to 160nm, so that the flexible liquid crystal display 30 has a lower light leakage and better optical performance (e.g., high contrast).
For example, at least one of the sum of the first thickness direction phase difference and the third thickness direction phase difference R1+ R3 and the sum of the second thickness direction phase difference and the fourth thickness direction phase difference R2+ R4 is 10nm to 110nm, preferably 40nm to 80 nm. It should be noted that the sum of the first and third thickness direction phase difference values R1+ R3 and the sum of the second and fourth thickness direction phase difference values R2+ R4 may be the same or different. Therefore, the light leakage of the flexible lcd 30 operating in the IPS mode or the FFS mode can be controlled to be less than 0.006% (preferably less than 0.005%, more preferably less than 0.004%), so as to improve the contrast at each viewing angle.
Referring to fig. 6A and 6B, the light leakage amount at each viewing angle of the IPS/FFS liquid crystal display using the glass substrate and the IPS/FFS liquid crystal display using the polyimide substrate and the optical compensation film of the present embodiment (for example, R1+ R3 is 60nm, and R2+ R4 is 60nm) are respectively shown, where the block R represents a portion with a large light leakage amount (the light leakage amount is greater than 0.006%), and LV represents the maximum light leakage amount in the entire region. As is clear from fig. 6A and 6B, when the sum of the first thickness direction phase difference R1 of the first flexible substrate 102, the second thickness direction phase difference R2 of the second flexible substrate 104, the third thickness direction phase difference R3 of the optical compensation film 200, and the fourth thickness direction phase difference R4 of the optical compensation film 300, R1+ R2+ R3+ R4, is 120nm, the light leakage amount at each viewing angle is significantly reduced compared to the liquid crystal display of the glass substrate, wherein the maximum light leakage amount in the whole area is reduced from 0.0071% to 0.0057%.
In some embodiments, the second optical compensation film 300 may be in direct contact with the second flexible substrate 104 and/or the second polarizer 108 without any other film therebetween. In addition, although the second optical compensation film 300 is a single film in the embodiment, if the above-mentioned condition related to the phase difference can be satisfied, in some other embodiments, the second optical compensation film 300 may also include a plurality of sub-layers.
In summary, the liquid crystal display according to the embodiments of the invention makes the flexible substrate and the optical compensation film have a proper phase difference in the thickness direction, so as to reduce the light leakage of the liquid crystal display and improve the optical performance of the liquid crystal display. In addition, the flexible substrate with proper thickness direction phase difference can improve the optical performance of the liquid crystal display and meet the requirement of flexibility.
Although the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (18)

1. A flexible liquid crystal display, comprising:
a liquid crystal layer; and
a first flexible substrate and a second flexible substrate sandwiching the liquid crystal layer;
wherein the first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, and the sum of the phase difference value in the first thickness direction and the phase difference value in the second thickness direction is 20nm to 220 nm;
wherein the flexible liquid crystal display operates in a transverse electric field switching mode or a boundary electric field switching mode;
and wherein the optical anisotropy of the first flexible substrate and the second flexible substrate is nx＝ny>nzWherein n isxIs the refractive index in the direction in which the in-plane refractive index is largest, nyIs a refractive index in a direction perpendicular to a direction in which an in-plane refractive index is maximum, nzIs the refractive index in the thickness direction of the film.
2. The flexible liquid crystal display of claim 1, wherein at least one of the first thickness direction phase difference value and the second thickness direction phase difference value is 10nm to 110 nm.
3. The flexible liquid crystal display of claim 1, wherein the sum of the first thickness direction phase difference and the second thickness direction phase difference is 80nm to 160 nm.
4. The device of claim 3, wherein at least one of the first thickness direction phase difference and the second thickness direction phase difference is 40nm to 80 nm.
5. A flexible liquid crystal display, comprising:
a liquid crystal layer;
a first flexible substrate and a second flexible substrate sandwiching the liquid crystal layer; and
a first optical compensation film disposed on the first flexible substrate;
wherein the first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, the first optical compensation film has a phase difference value in a third thickness direction, and the sum of the phase difference value in the first thickness direction, the phase difference value in the second thickness direction and the phase difference value in the third thickness direction is 20nm to 220 nm;
wherein the flexible liquid crystal display operates in a transverse electric field switching mode or a boundary electric field switching mode;
and wherein the light leakage amount of the flexible liquid crystal display is below 0.006%.
6. The device of claim 5, wherein at least one of the sum of the first thickness direction phase difference and the third thickness direction phase difference and the second thickness direction phase difference is 10nm to 110 nm.
7. The device of claim 5, wherein the sum of the first thickness direction phase difference, the second thickness direction phase difference and the third thickness direction phase difference is 80nm to 160 nm.
8. The flexible liquid crystal display of claim 7, wherein at least one of the sum of the first thickness direction phase difference and the third thickness direction phase difference and the second thickness direction phase difference is 40nm to 80 nm.
9. The device of claim 5, wherein the third thickness direction phase difference is 0nm to-500 nm.
10. A flexible liquid crystal display, comprising:
a liquid crystal layer;
a first flexible substrate and a second flexible substrate sandwiching the liquid crystal layer;
a first optical compensation film disposed on the first flexible substrate; and
a second optical compensation film disposed on the second flexible substrate;
wherein the first flexible substrate has a phase difference value in a first thickness direction, the second flexible substrate has a phase difference value in a second thickness direction, the first optical compensation film has a phase difference value in a third thickness direction, the second optical compensation film has a phase difference value in a fourth thickness direction, and the sum of the phase difference value in the first thickness direction, the phase difference value in the second thickness direction, the phase difference value in the third thickness direction and the phase difference value in the fourth thickness direction is 20nm to 220 nm;
wherein the flexible liquid crystal display operates in a transverse electric field switching mode or a boundary electric field switching mode;
and wherein the light leakage amount of the flexible liquid crystal display is below 0.006%.
11. The flexible liquid crystal display of claim 10, wherein at least one of the sum of the first thickness direction phase difference and the third thickness direction phase difference and the sum of the second thickness direction phase difference and the fourth thickness direction phase difference is 10nm to 110 nm.
12. The flexible liquid crystal display of claim 10, wherein the sum of the first thickness direction phase difference value, the second thickness direction phase difference value, the third thickness direction phase difference value and the fourth thickness direction phase difference value is 80nm to 160 nm.
13. The flexible liquid crystal display of claim 12, wherein at least one of the sum of the first thickness direction phase difference and the third thickness direction phase difference and the sum of the second thickness direction phase difference and the fourth thickness direction phase difference is 40nm to 80 nm.
14. The flexible liquid crystal display of claim 10, wherein at least one of the third thickness direction phase difference value and the fourth thickness direction phase difference value is 0nm to-500 nm.
15. The device of claim 1, 5 or 10, wherein the first flexible substrate and the second flexible substrate comprise polyimide, and/or at least one of the first flexible substrate and the second flexible substrate has a thickness of 1 μm to 25 μm.
16. The device of claim 1, 5 or 10, further comprising a first polarizer and a second polarizer respectively disposed on the first flexible substrate and the second flexible substrate.
17. The flexible liquid crystal display of claim 1, 5 or 10, wherein the first flexible substrate has a first in-plane retardation value and the second flexible substrate has a second in-plane retardation value, and wherein the first in-plane retardation value and the second in-plane retardation value are each 0 nm.
18. The device of claim 5 or 10, wherein the first flexible substrate and the second flexible substrate have optical anisotropy nx＝ny>nzWherein n isxIs the refractive index in the direction in which the in-plane refractive index is largest, nyIs a refractive index in a direction perpendicular to a direction in which an in-plane refractive index is maximum, nzIs the refractive index in the thickness direction of the film.
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