In-plane switching liquid crystal display

Abstract

An in-plane switching liquid crystal display, comprising a MiniLED backlight (101), a first polarizer (102), a liquid crystal cell (103) and a second polarizer (104), wherein the liquid crystal cell (103) is located between the first polarizer (102) and the second polarizer (104); the directions of the absorption axes of the first polarizer (102) and the second polarizer (104) are perpendicular to each other; the direction of the optical axis of the liquid crystal cell (103) is parallel to the absorption axis of the first polarizer (102); a first protective film (105) on the second polarizer (104) comprises a negative biaxial retardation film and a positive C-plate, the negative biaxial retardation film having an in-plane retardation value of 50-250 nm and a thickness-direction retardation value of 60-260 nm at a wavelength of 550 nm; and the positive C-plate has an in-plane retardation value of -20-20 nm and a thickness-direction retardation value of -300-0 nm at a wavelength of 550 nm. In this way, the problem of halos caused by using the MiniLED backlight (101) to perform local dimming can be solved.

Description

An in-plane switching liquid crystal display Technical Field

[0001] This application relates to the field of liquid crystal display technology, and specifically to an in-plane switching liquid crystal display. Background Technology

[0002] In-plane switching liquid crystal displays (IPS-LCDs) are among the most popular types of displays on the market. When the voltage of an IPS-LCD is off, the liquid crystals in the panel do not rotate, and the light passing through the polarizer at a normal viewing angle is completely absorbed by the analyzer, achieving excellent dark states. However, at oblique viewing angles, the effective angle between the absorption axes of the two polarizers is no longer perpendicular, resulting in light leakage and making the image appear washed out. Recently, to improve the contrast of IPS-LCDs, more and more displays are using MiniLED backlights for local dimming.

[0003] However, MiniLED chips are only about 200μm in size, making it easy to create hundreds or even thousands of backlight zones on large-size displays for precise dimming. MiniLEDs are turned on and off separately for bright and dark scenes by controlling logic switches. However, when both bright and dark scenes are present in the same backlight zone, the corresponding area's backlight is usually lit, causing a small amount of light to seep out from the black screen, creating a halo effect and affecting the visual experience. Summary of the Invention

[0004] This application addresses the aforementioned technical problems existing in the prior art. The purpose of this application is to provide an in-plane switching liquid crystal display that can improve the contrast and color shift between the front and side viewing angles, and can solve the light source problems caused by using MiniLED backlights.

[0005] According to a first aspect of this application, an in-plane switching liquid crystal display is provided, comprising: a MiniLED backlight, a first polarizer adjacent to the MiniLED backlight, a liquid crystal cell having a positive or negative dielectric constant, and a second polarizer, wherein the liquid crystal cell is located between the first polarizer and the second polarizer, and the absorption axes of the first polarizer and the second polarizer are perpendicular to each other, and the optical axis of the liquid crystal cell is parallel to the absorption axis of the first polarizer; both the first polarizer and the second polarizer include a first protective film, a polarizing film, and a second protective film, the polarizing film being located between the first protective film and the second protective film, and the first protective film being close to the... The liquid crystal cell; the first protective film on the second polarizer includes at least one negative biaxial retardation film and at least one positive C-plate, the first protective film on the first polarizer includes at least one positive C-plate, and the direction of the optical axis of the negative biaxial retardation film relative to the direction of the absorption axis of the second polarizer is determined based on the positional relationship between the negative biaxial retardation film and the second polarizer; the in-plane retardation value of the negative biaxial retardation film at a wavelength of 550nm is 50nm to 250nm, and the thickness direction retardation value is 60nm to 260nm; the in-plane retardation value of the positive C-plate at a wavelength of 550nm is -20nm to 20nm, and the thickness direction retardation value is -300nm to 0nm.

[0006] Compared with the prior art, the beneficial effects of the embodiments of this application are as follows:

[0007] The in-plane switching liquid crystal display provided in this application uses a compensation material to replace the first protective film, or adjusts the optical path together with the first protective film. The compensation material includes a negative biaxial retardation film and a positive C-plate. The negative biaxial retardation film and the positive C-plate have good light transmittance, exceeding 88%, and do not affect the original optical properties such as transmittance and polarization of the first and second polarizers. The negative biaxial retardation film provided in this application has an in-plane retardation value of 50nm to 250nm and a thickness direction retardation value of 60nm to 260nm at a wavelength of 550nm. The positive C-plate has an in-plane retardation value of -20nm to 20nm and a thickness direction retardation value of -300nm to 0nm at a wavelength of 550nm. Thus, the in-plane switching liquid crystal display fabricated based on this negative biaxial retardation film and the positive C-plate can improve the contrast between the front and side viewing angles, reduce color saturation with viewing angle, and improve the halo phenomenon caused by the MiniLED backlight.

[0008] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above description and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0009] In drawings that are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. Similar reference numerals with different letter suffixes may indicate different examples of similar components. The drawings generally illustrate various embodiments by way of example rather than limitation, and are used together with the specification and claims to illustrate the disclosed embodiments. Such embodiments are illustrative and exemplary, and are not intended to be exhaustive or exclusive embodiments of the method, apparatus, system, or non-transitory computer-readable medium having instructions for implementing the method.

[0010] Figure 1(a) shows a schematic diagram of the basic structure of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0011] Figure 1(b) shows a schematic diagram of the structure of a polarizer provided according to an embodiment of this application.

[0012] Figure 2 shows a schematic diagram of a first structure of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0013] Figure 3 shows a second structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0014] Figure 4 shows a third structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0015] Figure 5 shows a fourth structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0016] Figure 6 shows a fifth structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0017] Figure 7 shows a sixth structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0018] Figure 8 shows a seventh structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application.

[0019] Figure 9 shows an eighth structural schematic diagram of an in-plane switching liquid crystal display provided according to an embodiment of this application. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this application, the application will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific examples, but these are not intended to limit the scope of this application.

[0021] The terms "first," "second," and similar words used in this application do not indicate any order, quantity, or importance, but are merely used for distinction. The terms "including" or "comprising," etc., used in this application mean that the element preceding the word encompasses the elements listed after the word, and do not exclude the possibility of encompassing other elements. In this application, the arrows shown in the figures for each step are merely examples of the execution order, not limitations. The technical solution of this application is not limited to the execution order described in the embodiments. The steps in the execution order can be combined, broken down, or rearranged, as long as the logical relationship of the executed content is not affected.

[0022] All terms used in this application (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein. Technologies and equipment known to one of ordinary skill in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0023] Figure 1(a) shows a schematic diagram of the basic structure of an in-plane switching liquid crystal display provided according to an embodiment of this application. The in-plane switching liquid crystal display includes a MiniLED backlight 101, a first polarizer 102 adjacent to the MiniLED backlight 101, a liquid crystal cell 103 having a positive dielectric constant (Δε>0) or a negative dielectric constant (Δε<0), and a second polarizer 104. The liquid crystal cell 103 is located between the first polarizer 102 and the second polarizer 104, and the absorption axes of the first polarizer 102 and the second polarizer 104 are perpendicular to each other. The optical axis of the liquid crystal cell 103 is parallel to the absorption axis of the first polarizer 102.

[0024] MiniLED backlight 101 is a relatively new display technology, which began industrialization in 2018 and has gradually penetrated the high-end display field after several years of technological development. Compared with traditional LED backlights, it has higher brightness, better contrast, and more precise local dimming capabilities. MiniLED backlight 101 typically has a size of 100 to 200 micrometers, much smaller than traditional LEDs, but slightly larger than MicroLEDs. Due to its small size, more MiniLEDs can be placed in the same size display backlight module, thereby improving the display effect.

[0025] However, the inventors of this application discovered that when using the MiniLED backlight 101, a small amount of light seeps out from a black screen, producing a halo effect. This halo effect only exists when using the MiniLED backlight 101, and does not occur with other backlights. Traditional backlights control the backlight to turn on or off via a single switch, without a clear boundary between bright and dark areas, thus eliminating the halo effect. Therefore, improving or reducing the halo effect has become a pressing technical problem to be solved when adjusting the light path using the MiniLED backlight 101.

[0026] The first polarizer 102 is equivalent to a polarizer, which converts the light provided by the MiniLED backlight 101 into polarized light. The second polarizer 104 is equivalent to a polarizer, which can absorb polarized light in a direction parallel to the transmission axis of the first polarizer 102.

[0027] The liquid crystal unit 103 is located between the first polarizer 102 and the second polarizer 104. The alignment of the liquid crystal molecules can be controlled by applying different voltages to the electrodes of the liquid crystal unit 103. Generally, the MiniLED backlight 101 provides the light source, and the emitted light passes through the first polarizer 102, allowing only light from specific directions to pass through. When light passes through the liquid crystal unit 103, if no voltage is applied, the liquid crystal molecules in the liquid crystal unit 103 align naturally, allowing the light to continue passing through the second polarizer 104. If a voltage is applied, the alignment of the liquid crystal molecules in the liquid crystal unit 103 is changed, thereby altering the state of the light passing through the liquid crystal layer. Finally, the light passes through the second polarizer 104 and reaches the surface of the display to form the final image.

[0028] The design that the absorption axes of the first polarizer 102 and the second polarizer 104 are perpendicular to each other helps to ensure that the liquid crystal layer of the liquid crystal cell 103 can change the polarization state of light according to the applied electric field, thereby controlling the transmittance of light and effectively utilizing the optical effect of liquid crystal molecules under the action of an electric field to achieve high-quality image display.

[0029] As shown in Figure 1(b), both the first polarizer 102 and the second polarizer 104 include a first protective film 105, a polarizing film 106, and a second protective film 107. The polarizing film 106 is located between the first protective film 105 and the second protective film 107, and the first protective film 105 is close to the liquid crystal cell 103. Polarizers are fragile optical components, easily damaged by mechanical scratches or chemical corrosion. The protective film effectively prevents these external factors from directly damaging the polarizer, extending its service life. Furthermore, the protective film can improve the optical transmittance and contrast of the polarizer, thereby enhancing the visual quality and user experience of the display device.

[0030] The first protective film 105 on the second polarizer 104 includes at least one negative biaxial retardation film and at least one positive C-plate. The first protective film 105 on the first polarizer 102 also includes at least one positive C-plate. The direction of the optical axis of the negative biaxial retardation film relative to the absorption axis of the second polarizer 104 is determined based on the positional relationship between the negative biaxial retardation film and the second polarizer 104. The negative biaxial retardation film and the positive C-plate, having a specific optical retardation range, serve as compensation materials and can replace the first protective film 105 or be used together with the first protective film 105 to adjust the optical path. The compensation material can be bonded to other components of the first polarizer 102 and the second polarizer 104 via roll-to-roll bonding. The use of the compensation material has no adverse effect on the original optical properties of the first polarizer 102 and the second polarizer 104, such as transmittance and polarization.

[0031] Specifically, a negative biaxial retardation film and a positive C-plate are disposed between the second polarizer 104 and the liquid crystal unit 103. The negative biaxial retardation film or the positive C-plate can replace the first protective film 105 of the second polarizer 104, or can be attached to the first protective film 105 for adjusting the optical path. The placement of the negative biaxial retardation film and the positive C-plate is not limited. For example, the negative biaxial retardation film can be placed immediately adjacent to the second polarizer 104, or the positive C-plate can be placed between the negative biaxial retardation film and the second polarizer 104; this is merely an example.

[0032] The negative biaxial retardation film has an in-plane retardation value of 50nm to 250nm and a thickness retardation value of 60nm to 260nm at a wavelength of 550nm; the positive C-plate has an in-plane retardation value of -20nm to 20nm and a thickness retardation value of -300nm to 0nm at a wavelength of 550nm. An in-plane switching liquid crystal display fabricated based on this specific retardation range of the negative biaxial retardation film and the positive C-plate can improve the contrast and color shift at both the front and side viewing angles when using the MiniLED backlight 101, and can effectively improve the halo effect caused by the MiniLED backlight 101.

[0033] In this application, the in-plane retardation value (Rin) and the thickness direction retardation value (Rth) are defined as follows: Rin = (nx - ny) × d; Rth = {(nx + ny) / 2 - nz} × d;

[0034] nx, ny, and nz are the refractive indices of the retardation film in the x-axis, y-axis, and z-axis directions, respectively, and d is the thickness of the retardation film.

[0035] In some embodiments of this application, the negative biaxial retardation film has an in-plane retardation value of 100nm to 150nm and a thickness direction retardation value of 75nm to 110nm at a wavelength of 550nm; the positive C-plate has an in-plane retardation value of -10nm to 10nm and a thickness direction retardation value of -150nm to -100nm at a wavelength of 550nm. The inventors of this application have discovered that the negative biaxial retardation film and positive C-plate within this specific retardation value range, as compensation materials, can more effectively adjust the optical path, reduce light leakage, further reduce halo phenomena, and the resulting weak halo can be ignored. Furthermore, simulation verification shows that when the retardation values ​​of the negative biaxial retardation film and positive C-plate exceed the specific retardation range provided in this embodiment, the resulting halo phenomenon is still significant and cannot be ignored, affecting the visual experience.

[0036] Preferably, the negative biaxial retardation film has an in-plane retardation value of 130 nm and a thickness direction retardation value of 100 nm at a wavelength of 550 nm, while the positive C-plate has an in-plane retardation value of 0.1 nm and a thickness direction retardation value of -140 nm at a wavelength of 550 nm. Thus, the simulated in-plane switching liquid crystal display can achieve a contrast ratio of 155 at a tilt angle of 70°, which can effectively improve the halo phenomenon caused by the MiniLED backlight 101.

[0037] In some embodiments of this application, the optical axis of the liquid crystal unit 103 is parallel to the absorption axis of the first polarizer 102. This parallelism maximizes the utilization of the birefringence characteristics of the liquid crystal unit 103, helps optimize the optical performance and display effect of the liquid crystal display, and ensures effective control of the polarization state of light, thereby achieving high-quality image display.

[0038] When the negative biaxial retardation film is adjacent to the second polarizer 104, the optical axis of the negative biaxial retardation film is perpendicular to the absorption axis of the second polarizer 104. When the negative biaxial retardation film is not adjacent to the second polarizer 104, the optical axis of the negative biaxial retardation film is parallel to the absorption axis of the second polarizer 104. In this way, light leakage at the tilt angle can be effectively reduced.

[0039] Specifically, Figure 2 illustrates the structure of an in-plane switching liquid crystal display. A negative biaxial retardation film 108 and a positive C-plate 109 are disposed between the liquid crystal cell 103 and the second polarizer 104. The negative biaxial retardation film 108 is adjacent to the second polarizer 104, and the positive C-plate 109 is located between the negative biaxial retardation film 108 and the liquid crystal cell 103. The liquid crystals in the liquid crystal cell 103 are arranged perpendicular to the horizontal plane. Specifically, the arrangement of the liquid crystals in the liquid crystal cell 103 perpendicular to the horizontal plane can maintain good contrast and color performance when the viewing angle changes. The rotation direction of the liquid crystal molecules can more effectively control the polarization direction of light, reducing light loss at large viewing angles.

[0040] In this embodiment, the negative biaxial retardation film 108 and the second polarizer 104 are adjacent. Since the absorption axis and transmission axis of the second polarizer 104 are perpendicular, the optical axis of the negative biaxial retardation film 108 and the absorption axis of the second polarizer 104 are perpendicular. The absorption axis of the second polarizer 104 is perpendicular to the optical axis of the liquid crystal cell 103, which can reduce light leakage caused by the intersecting second polarizers 104.

[0041] In some embodiments of this application, as shown in FIG3, a negative biaxial retardation film 108 and a positive C-plate 109 are disposed between the liquid crystal cell 103 and the second polarizer 104. The negative biaxial retardation film 108 is adjacent to the liquid crystal cell 103, and the positive C-plate 109 is located between the negative biaxial retardation film 108 and the second polarizer 104. The liquid crystals in the liquid crystal cell 103 are arranged perpendicular to the horizontal plane. The second polarizer 104 and the positive C-plate 109 are adjacent, and the negative biaxial retardation film 108 and the liquid crystal cell 103 are adjacent. The absorption axis of the second polarizer 104 is parallel to the optical axis of the negative biaxial retardation film 108, and the optical axis of the liquid crystal cell 103 is perpendicular to the optical axis of the negative biaxial retardation film 108. The negative biaxial retardation film 108 and the positive C-plate, as compensation materials, are placed between the second polarizer 104 and the liquid crystal cell 103. By adjusting the direction of the optical axis of the negative biaxial retardation film 108, the color shift with viewing angle can be reduced.

[0042] The positive C-plate 109 has a thickness retardation value of -300nm to 0nm. It can be divided into a first positive C-plate and a second positive C-plate, such that the sum of the thickness retardation values ​​of the first and second positive C-plates is -300nm to 0nm. Specifically, as shown in Figure 4, a negative biaxial retardation film 108 and a first positive C-plate 1091 are disposed between the liquid crystal cell 103 and the second polarizer 104. The negative biaxial retardation film 108 is adjacent to the second polarizer 104. The first positive C-plate 1091 is disposed between the negative biaxial retardation film 108 and the liquid crystal cell 103, and the liquid crystal in the liquid crystal cell 103 is arranged perpendicular to the horizontal plane. A second positive C-plate 1092 is disposed between the liquid crystal cell 103 and the first polarizer 102, and the sum of the thickness retardation values ​​of the first positive C-plate 1091 and the second positive C-plate 1092 is -300nm to 0nm.

[0043] This liquid crystal display structure, by incorporating a second positive C-plate 1092 between the liquid crystal cell 103 and the first polarizer 102, further enhances display stability and makes details in dark areas clearer. Simultaneously, when used in conjunction with the MiniLED backlight 101, it helps reduce halo effects caused by the MiniLED backlight 101.

[0044] When the first positive C-plate 1091 is located between the second polarizer 104 and the negative biaxial retardation film 108, the optical axis of the negative biaxial retardation film 108 is parallel to the absorption axis of the second polarizer 104, thus providing an in-plane switching liquid crystal display. The negative biaxial retardation film 108 and the first positive C-plate 1091 are disposed between the liquid crystal cell 103 and the second polarizer 104. The negative biaxial retardation film 108 is adjacent to the liquid crystal cell 103, and the first positive C-plate 1091 is between the negative biaxial retardation film 108 and the second polarizer 104. The liquid crystals of the liquid crystal cell 103 are arranged perpendicular to the horizontal plane. The second positive C-plate 1092 is disposed between the liquid crystal cell 103 and the first polarizer 102. The sum of the thickness direction retardation values ​​of the first positive C-plate 1091 and the second positive C-plate 1092 is -300nm to 0nm.

[0045] In other embodiments of this application, an in-plane switching liquid crystal display is provided, as shown in FIG6. A negative biaxial retardation film 108 and a positive C-plate 109 are disposed between the liquid crystal cell 103 and the second polarizer 104. The negative biaxial retardation film 108 is adjacent to the second polarizer 104, and the positive C-plate 109 is between the negative biaxial retardation film 108 and the liquid crystal cell 103. The liquid crystals in the liquid crystal cell 103 are arranged horizontally. Horizontally arranged liquid crystal displays typically have a faster response speed. In horizontal arrangement, the rotation of liquid crystal molecules does not need to overcome too much resistance, and their polarization state can be changed more quickly.

[0046] When the liquid crystals in the liquid crystal cell 103 are horizontally aligned, the optical axis of the first polarizer 102 is parallel to the horizontal direction, and the absorption axis of the second polarizer 104 is perpendicular to the horizontal direction. For example, based on the arrangement shown in FIG6, simulations show that with the negative biaxial retardation film 108 having an in-plane retardation of 84 nm and a thickness retardation of 171 nm at a wavelength of 550 nm, and the positive C-plate 109 having a thickness retardation of -204 nm and an in-plane retardation of 10 nm at a wavelength of 550 nm, the simulation results show a minimum contrast ratio of 87 at a 70° tilt angle, with no obvious halo effect. With the negative biaxial retardation film 108 having an in-plane retardation of 41 nm and a thickness retardation of 56 nm at a wavelength of 550 nm, and the positive C-plate 109 having a thickness retardation of -22 nm and an in-plane retardation of 1 nm at a wavelength of 550 nm, the simulation results show a minimum contrast ratio of 66 at a 70° tilt angle, with a non-negligible halo effect.

[0047] In some other embodiments of this application, an in-plane switching liquid crystal display is provided, as shown in FIG7. A negative biaxial retardation film 108 and a positive C-plate 109 are disposed between the liquid crystal cell 103 and the second polarizer 104. The negative biaxial retardation film 108 is adjacent to the liquid crystal cell 103, and the positive C-plate 109 is between the negative biaxial retardation film 108 and the second polarizer 104. The liquid crystals of the liquid crystal cell 103 are arranged horizontally. For example, based on the arrangement shown in Figure 7, when the negative biaxial retardation film 108 has an in-plane retardation value of 115 and a thickness direction retardation value of 99 nm at a wavelength of 550 nm, and the positive C-plate 109 has a thickness direction retardation value of -125 nm and an in-plane retardation value of 3 nm at a wavelength of 550 nm, the simulation results show that the minimum contrast ratio at a 70° tilt angle is 160, and there is no obvious halo phenomenon. When the negative biaxial retardation film 108 has an in-plane retardation value of 45 nm and a thickness direction retardation value of 300 nm at a wavelength of 550 nm, and the positive C-plate 109 has a thickness direction retardation value of -310 nm and an in-plane retardation value of 10 nm at a wavelength of 550 nm, the simulation results show that the minimum contrast ratio at a 70° tilt angle is 54, and there is a non-negligible halo.

[0048] In other embodiments of this application, an in-plane switching liquid crystal display is provided, as shown in FIG8. A negative biaxial retardation film 108 and a first positive C-plate 1091 are disposed between a liquid crystal cell 103 and a second polarizer 104. The negative biaxial retardation film 108 is adjacent to the second polarizer 104. The first positive C-plate 1091 is disposed between the negative biaxial retardation film 108 and the liquid crystal cell 103. The liquid crystals in the liquid crystal cell 103 are arranged horizontally. A second positive C-plate 1092 is disposed between the liquid crystal cell 103 and the first polarizer 102. The sum of the thickness direction retardation values ​​of the first positive C-plate 1091 and the second positive C-plate 1092 is -300nm to 0nm. For example, based on the arrangement shown in Figure 8, when the negative biaxial retardation film 108 has an in-plane retardation value of 117 nm and a thickness direction retardation value of 103 nm at a wavelength of 550 nm, and the positive C-plate 109 has a thickness direction retardation value of -120 nm and an in-plane retardation value of -2 nm at a wavelength of 550 nm, the simulation results show that the minimum contrast ratio at a 70° tilt angle is 113, and there is no obvious halo phenomenon. When the negative biaxial retardation film 108 has an in-plane retardation value of 150 nm and a thickness direction retardation value of 10 nm at a wavelength of 550 nm, and the positive C-plate 109 has a thickness direction retardation value of 30 nm and an in-plane retardation value of 10 nm at a wavelength of 550 nm, the simulation results show that the minimum contrast ratio at a 70° tilt angle is 91, and there is a non-negligible halo.

[0049] In other embodiments of this application, an in-plane switching liquid crystal display is provided, as shown in FIG9. A negative biaxial retardation film 108 and a first positive C-plate 1091 are disposed between a liquid crystal cell 103 and a second polarizer 104. The negative biaxial retardation film 108 is adjacent to the liquid crystal cell 103, and the first positive C-plate 1091 is disposed between the negative biaxial retardation film 108 and the second polarizer 104. The liquid crystals in the liquid crystal cell 103 are arranged horizontally. A second positive C-plate 1092 is disposed between the liquid crystal cell 103 and the first polarizer 102. The sum of the thickness direction retardation values ​​of the first positive C-plate 1091 and the second positive C-plate 1092 is -300 to 0 nm. For example, based on the arrangement shown in Figure 9, when the negative biaxial retardation film 108 has an in-plane retardation value of 141 nm and a thickness direction retardation value of 84 nm at a wavelength of 550 nm, and the positive C-plate 109 has a thickness direction retardation value of -104 nm and an in-plane retardation value of 1 nm at a wavelength of 550 nm, the simulation results show that the minimum contrast ratio at a 70° tilt angle is 138, and there is no obvious halo phenomenon. When the negative biaxial retardation film 108 has an in-plane retardation value of 50 nm and a thickness direction retardation value of -100 nm at a wavelength of 550 nm, and the positive C-plate 109 has a thickness direction retardation value of 30 nm and an in-plane retardation value of 10 nm at a wavelength of 550 nm, the simulation results show that the minimum contrast ratio at a 70° tilt angle is 62, and there is a non-negligible halo.

[0050] In other words, when the liquid crystals in the liquid crystal cell 103 are arranged horizontally, preferably, the in-plane retardation value of the negative biaxial retardation film at a wavelength of 550nm is 100nm to 130nm, and the thickness direction retardation value is 75nm to 110nm, while the thickness direction retardation value of the positive C-plate at a wavelength of 550nm is -150nm to -100nm. This improves the contrast ratio of the liquid crystal display at tilt angles, effectively reduces light leakage at the boundary between the luminous and dark areas at oblique viewing angles, and further reduces or even eliminates the halo effect generated by the MiniLED backlight 101.

[0051] In some embodiments of this application, the negative biaxial retardation film is made of uniaxially stretched cellulose triacetate, uniaxially stretched polynorbornene, biaxially stretched polycarbonate, uniaxially or biaxially stretched cyclic olefin polymers, or UV-cured liquid crystal film, while the positive C-plate is made of polymer material or UV-cured liquid crystal film, so that the negative biaxial retardation film has good light transmittance. Preferably, the negative biaxial retardation film is prepared from one of biaxially stretched polycarbonate, uniaxially or biaxially stretched cyclic olefin polymers, to further improve the light transmittance of the negative biaxial retardation film and ensure optimal rendering speed and color reproduction in the liquid crystal display. Furthermore, these two materials have the advantage of stable phase difference, and can still achieve the same optical compensation effect as at room temperature even when the backlight heats up, ensuring viewing angle stability.

[0052] The above description is intended to be illustrative and not restrictive. For example, the above examples (or one or more of them) can be used in combination with each other. Other embodiments may be used by those skilled in the art upon reading the above description. Furthermore, in the above detailed description, various features may be grouped together to simplify the application. This should not be construed as an intention that a disclosed feature not claimed is necessary for any claim. Rather, the subject matter of the application may be less than all the features of a particular disclosed embodiment. Thus, the claims are incorporated herein by reference as examples or embodiments, wherein each claim is an independent, separate embodiment, and these embodiments are contemplated as being combined with each other in various combinations or arrangements. The scope of this application should be determined by reference to the appended claims and the full scope of their equivalents.

[0053] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. An in-plane switching liquid crystal display, characterized in that, include: The system comprises a MiniLED backlight, a first polarizer adjacent to the MiniLED backlight, a liquid crystal cell having a positive or negative dielectric constant, and a second polarizer, wherein the liquid crystal cell is located between the first polarizer and the second polarizer, and the absorption axes of the first polarizer and the second polarizer are perpendicular to each other, and the optical axis of the liquid crystal cell is parallel to the absorption axis of the first polarizer. Both the first polarizer and the second polarizer include a first protective film, a polarizing film, and a second protective film. The polarizing film is located between the first protective film and the second protective film, and the first protective film is close to the liquid crystal cell. The first protective film on the second polarizer includes at least one negative biaxial retardation film and at least one positive C-plate. The first protective film on the first polarizer includes at least one positive C-plate. Furthermore, the direction of the optical axis of the negative biaxial retardation film relative to the direction of the absorption axis of the second polarizer is determined based on the positional relationship between the negative biaxial retardation film and the second polarizer. The negative biaxial retardation film has an in-plane retardation value of 100nm to 150nm at a wavelength of 550nm and a thickness direction retardation value of 75nm to 100nm. The positive C-plate has an in-plane retardation value of 1nm to 10nm at a wavelength of 550nm, and a thickness retardation value of -150nm to -100nm.

2. The in-plane switching liquid crystal display according to claim 1, characterized in that, The optical axis of the liquid crystal unit is parallel to the absorption axis of the first polarizer, and When the negative biaxial retardation film is adjacent to the second polarizer, the optical axis of the negative biaxial retardation film is perpendicular to the absorption axis of the second polarizer. When the negative biaxial retardation film is not adjacent to the second polarizer, the optical axis of the negative biaxial retardation film is parallel to the absorption axis of the second polarizer.

3. The in-plane switching liquid crystal display according to claim 2, characterized in that, A negative biaxial retardation film and a positive C-plate are disposed between the liquid crystal cell and the second polarizer. The negative biaxial retardation film is adjacent to the second polarizer, and the positive C-plate is between the negative biaxial retardation film and the liquid crystal cell. The liquid crystals in the liquid crystal cell are arranged perpendicular to the horizontal plane.

4. The in-plane switching liquid crystal display according to claim 2, characterized in that, A negative biaxial retardation film and a positive C-plate are disposed between the liquid crystal cell and the second polarizer. The negative biaxial retardation film is adjacent to the liquid crystal cell, and the positive C-plate is between the negative biaxial retardation film and the second polarizer. The liquid crystals in the liquid crystal cell are arranged perpendicular to the horizontal plane.

5. The in-plane switching liquid crystal display according to claim 2, characterized in that, The positive C-plate includes a first positive C-plate and a second positive C-plate; A negative biaxial retardation film and a first positive C-plate are disposed between a liquid crystal cell and a second polarizer. The negative biaxial retardation film is adjacent to the second polarizer, and the first positive C-plate is between the negative biaxial retardation film and the liquid crystal cell. The liquid crystals in the liquid crystal cell are arranged perpendicular to the horizontal plane. A second positive C-plate is disposed between the liquid crystal cell and the first polarizer, wherein the sum of the thickness direction retardation values ​​of the first positive C-plate and the second positive C-plate is -300nm to 0nm.

6. The in-plane switching liquid crystal display according to claim 2, characterized in that, The positive C-plate includes a first positive C-plate and a second positive C-plate; A negative biaxial retardation film and a first positive C-plate are disposed between a liquid crystal cell and a second polarizer. The negative biaxial retardation film is adjacent to the liquid crystal cell, and the first positive C-plate is between the negative biaxial retardation film and the second polarizer. The liquid crystals in the liquid crystal cell are arranged perpendicular to the horizontal plane. A second positive C-plate is disposed between the liquid crystal cell and the first polarizer, wherein the sum of the thickness direction retardation values ​​of the first positive C-plate and the second positive C-plate is -300nm to 0nm.

7. The in-plane switching liquid crystal display according to claim 2, characterized in that, A negative biaxial retardation film and a positive C-plate are disposed between the liquid crystal cell and the second polarizer. The negative biaxial retardation film is adjacent to the second polarizer, and the positive C-plate is between the negative biaxial retardation film and the liquid crystal cell. The liquid crystals in the liquid crystal cell are arranged horizontally.

8. The in-plane switching liquid crystal display according to claim 2, characterized in that, A negative biaxial retardation film and a positive C-plate are disposed between the liquid crystal cell and the second polarizer. The negative biaxial retardation film is adjacent to the liquid crystal cell, and the positive C-plate is between the negative biaxial retardation film and the second polarizer. The liquid crystals in the liquid crystal cell are arranged horizontally.

9. The in-plane switching liquid crystal display according to claim 2, characterized in that, The positive C-plate includes a first positive C-plate and a second positive C-plate; A negative biaxial retardation film and a first positive C-plate are disposed between a liquid crystal cell and a second polarizer. The negative biaxial retardation film is adjacent to the second polarizer, and the first positive C-plate is between the negative biaxial retardation film and the liquid crystal cell. The liquid crystals in the liquid crystal cell are arranged horizontally. A second positive C-plate is disposed between the liquid crystal cell and the first polarizer, wherein the sum of the thickness direction retardation values ​​of the first positive C-plate and the second positive C-plate is -300nm to 0nm.

10. The in-plane switching liquid crystal display according to claim 2, characterized in that, The positive C-plate includes a first positive C-plate and a second positive C-plate; A negative biaxial retardation film and a first positive C-plate are disposed between a liquid crystal cell and a second polarizer. The negative biaxial retardation film is adjacent to the liquid crystal cell, and the first positive C-plate is between the negative biaxial retardation film and the second polarizer. The liquid crystals in the liquid crystal cell are arranged horizontally. A second positive C-plate is disposed between the liquid crystal cell and the first polarizer, wherein the sum of the thickness direction retardation values ​​of the first positive C-plate and the second positive C-plate is -300nm to 0nm.

11. The in-plane switching liquid crystal display according to any one of claims 1-10, characterized in that, The negative biaxial delay film is made of uniaxially stretched cellulose triacetate, uniaxially stretched polynorbornene, biaxially stretched polycarbonate, uniaxially or biaxially stretched cyclic olefin polymers, or UV-cured liquid crystal film; the positive C-plate is made of polymer materials or UV-cured liquid crystal film.

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