TW202030535A - Enhanced quantum dot on color filter lcd - Google Patents

Abstract

A quantum dots on color filter (QDCF) LCD apparatus having certain combinations of enhancement features that enhance contrast ratio by eliminating or minimizing high angle incident light within the LCD stack is disclosed.

Description

Enhanced quantum dots on color filter LCD

cross reference

According to Article 119 of the U.S. Patent Law, this application claims the priority right of U.S. Provisional Application No. 62/798607 and No. 62/773449 filed on January 30, 2019 and November 30, 2018, respectively. The respective contents of these patent applications are fully incorporated herein by reference.

This disclosure is related to the enhanced quantum dots on the color filter LCD.

The liquid crystal display (LCD) industry is seeking solutions that increase the efficiency of LCDs and improve their color gamut (color content of the display) in order to compete with organic light emitting display (OLED) products. Traditional LCD lags behind OLED in terms of color gamut performance. The use of quantum dots (QD) in liquid crystal displays improves the color gamut performance of liquid crystal displays; in fact, such improvements are already obvious in LCD design, where QD thin-film elements are used in backlight units (BLU), that is, the light provided is pixelated by LCD The liquid crystal (LC) of the panel fills the light source of the active matrix of pixels. In these BLU designs, the blue LED light is coupled to the light guide plate (LGP), and the blue LED light is obtained from the LGP toward the LCD pixelated panel. Then, the guided blue light encounters the QD, and the QD absorbs part of the blue light and emits light in the green and red spectrum. The generated red, green, and blue spectrum light provides a white light source for the LCD pixelated panel.

In other designs, the QD material is placed directly in the corresponding individual pixels in the LCD pixelated panel. This design not only ensures a larger color gamut, but also potentially replaces the color filter (CF) that defines the color of individual pixels in traditional (QD-free) LCD designs. Such a design is called a "quantum dot on color filter" (QDCF) design. In the QDCF design, the QD pixel is placed after (where) the light encounters two polarizers, which are part of the LCD, and these polarizers work with the LC to manipulate the polarization of the light.

Even a pair of perfect polarizers will cause the light incident on it to leak in the direction "non-normal to the plane of the sheet polarizer" (the normal direction is perpendicular to the surface of the emitting element). Figures 1A and 1B show light transmission through a pair of crossed polarizers with a phase retarder between the polarizers to mimic the LC medium as a function of viewing angle. 1A and 1B respectively show the light transmission through a pair of crossed polarizers as a function of viewing angle (the normal viewing angle is in the center of the figure) when the pixel is in the "on" and "off" states. The x-axis and y-axis are marked as H and V, which respectively indicate the "horizontal" and "vertical" angles (in degrees) that deviate from the normal viewing angle (center of the figure) in the horizontal and vertical directions. Figure 1A shows the light emitted from a conventional LCD and transmitted through a pair of crossed polarizers in an on state. High-angle rays will cause the contrast (CR) to drop sharply at high incident angles (or viewing angles). Therefore, the darker area near the periphery of FIG. 1A with a viewing angle of 90 degrees shows a lower transmission rate at a higher viewing angle. FIG. 1B shows that light emitted from the LCD in the off state (ie, light leakage) transmits light through a pair of crossed polarizers.

Comparing the light emission between the on and off states shown in FIGS. 1A and 1B, in a conventional LCD, high-angle light will cause the contrast ratio (CR) to drop sharply at a high incident angle (or viewing angle). CR measures the ratio of the light when the LCD is on to the light when the LCD is off. Ideally, for all incident angles, the closed state should be as dark as possible, so the closed state is called the dark state. CR is very sensitive to light in the dark state (denominator). Even if there is only a small amount of light in the dark state, CR will be significantly reduced.

In the QDCF simulation, the inventor observed that the sharp drop in CR was the result of light leakage through the high viewing angle of the polarizer. In a conventional LCD, the leaked light still remains towards a high viewing angle, while in QDCF, this light is significantly scattered, including a blue light source. This means that the leaked light also faces an angle close to the normal viewing angle, and the value of the light in the denominator defined by the normal (and other directions) CR is increased, thereby effectively averaging CR at various viewing angles. Such an average does not meet the demand and greatly reduces CR.

FIG. 2A is a CR drawing of a conventional LCD example, and FIG. 2B is a CR drawing of a conventional QDCF. The x-axis and y-axis H and V are marked to indicate the "horizontal" and "vertical" angles viewed from the normal in the horizontal and vertical directions (the center of the figure). Figure 2A shows the CR of a conventional LCD. The CR of a conventional LCD is calculated to be ~3200:1 under the normal viewing angle (both horizontal and vertical angles are at 0 degrees), which is represented by the peak in the center of the drawing, but decreases significantly as the horizontal and vertical viewing angles increase. Therefore, if the viewer does not view the LCD with a normal viewing angle, CR in the conventional LCD is significantly deteriorated. This provides viewers with a very uneven viewing experience. Figure 2B shows the CR of the QDCF LCD. The CR of QDCF LCD is more uniform, but its value is very low for the viewer, about 128:1. Low CR will cause the viewer's picture quality to deteriorate. Even if the CR under normal viewing angle can have a value of several thousand seconds (a vertically aligned LC mode display can have a CR value of ~5000), the CR will still drop to >10 for high viewing angles.

QD-based displays generally provide higher color accuracy and a wider color gamut. The current technology uses blue LEDs for backlighting and a QD film that uses a mixture of red and green QDs inside the backlight unit (BLU) to convert blue light into white. Because the conversion is done in color filters (CF's) instead of BLU, another concept of QDCF allows for a better color gamut. In these designs, the short-pass filter is located between the QD layer/color filter layer and the BLU. In another method disclosed in US Patent Application Publication No. US2017/0153366, a band-cut filter is used to filter out blue light after conversion, and the content of this patent is incorporated herein by reference. US2017/0153366 also describes a solution using ultraviolet light from backlight and blue QD.

Another problem observed in these designs is that, in addition to the low CR, light with a high exit angle will also be trapped inside the cover glass due to total internal reflection (TIR). In traditional LCD design, light output is usually concentrated in certain limited output angles, so TIR is not a limiting factor. However, in the QDCF design, the QD layer re-emits light at various angles, so significant light experiences TIR. The light reflected by the TIR may be absorbed by color filters (CFs) of different colors or the same color (a typical absorption CF has a transmission rate of 80% to 90%), resulting in a significant reduction in the amount of light emitted by the LCD.

Therefore, there is a need for an improved QDCF architecture with improved CR.

According to the embodiments of the present disclosure, a QDCF LCD device is disclosed. Quantum dot color filter (QDCF) liquid crystal display (LCD) device, including: cover glass; back reflector layer; liquid crystal panel layer between cover glass and back reflector layer; between liquid crystal panel layer and back reflector The backlight unit is configured to generate image forming light to the liquid crystal panel layer; the quantum dot layer between the cover glass and the liquid crystal panel layer; the color filter layer between the cover glass and the quantum dot layer, the color filter And the quantum dot layer combination is configured to form a color by converting a wavelength of the image forming light from the backlight unit and penetrating the liquid crystal panel; the bottom polarizer layer located between the liquid crystal panel layer and the backlight unit; The top polarizer layer between the quantum dot layers; and further includes one or more of the following enhancement features: (a) Provide a low refractive index material layer (LIML) between the color filter layer and the quantum dot layer; (b) A backlight unit configured to generate collimated image forming light to the liquid crystal panel layer; (c) One or both of the bottom polarizer and the top polarizer are made of E-type polarizer material; (d) The bottom polarizer and the top polarizer are each made of compensation film, the compensation film includes one or more of A plate, C plate, and biaxial plate; and (e) Provide a privacy filter film between the top polarizer and the quantum dot layer.

According to some embodiments, the QDCF LCD device includes a backlight unit and LIML, the backlight unit is configured to generate image forming light to the liquid crystal panel layer, the LIML is provided between the color filter layer and the quantum dot layer; and further includes one of the following: More enhanced features: (a) One or both of the bottom polarizer and the top polarizer are made of E-type polarizer material; (b) A backlight unit configured to generate collimated image forming light to the liquid crystal panel layer; (c) The bottom polarizer and the top polarizer are each made of compensation film, which includes one or more of A plate, C plate, and biaxial plate; and (d) Provide a privacy filter film between the top polarizer and the quantum dot layer.

It should be understood that the foregoing general description and the following detailed description propose embodiments of the present disclosure, and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter. The accompanying schematic diagram contained herein provides a further understanding of the content of the disclosure, and is incorporated into this specification and constitutes a part of this specification. The illustrations in this document show different embodiments of the disclosure, and are used together with the narrative to explain the principles and operations of the claimed subject matter.

Various embodiments of the luminescent coating and device are described with reference to the drawings, in which similar elements have been given similar element symbols to facilitate understanding.

It should also be understood that, unless otherwise specified, terms such as "top", "bottom", "outward", "inward" and other terms are convenient terms and should not be interpreted as restrictive terms. In addition, whenever a group is described as including at least one of a group of elements and a combination thereof, the group can include these elements, basically consist of these elements alone or a combination of these elements, Or it is composed of any number of these elements or combinations of such tuples alone.

Similarly, whenever a group is described as being composed of at least one element of a group of elements or a combination thereof, the group can be composed of any number of such elements or combinations of such elements alone. Unless otherwise stated, the upper and lower limits of this range are included when specifying the value range. As used herein, unless otherwise specified, the indefinite article "一 (a)" or "一 (an)" and its corresponding definite article "the" used herein refer to at least one, or one or more.

Those familiar with the art will recognize that many changes can be made to the described embodiments while still obtaining beneficial results for the disclosure. It is also obvious that some of the benefits of the disclosure can be obtained by selecting some of the described features without using other features. Therefore, those skilled in the art will recognize that many modifications and adaptations are possible, and in some cases even meet the needs, and are part of the disclosure content. Therefore, the following description is provided to illustrate the principle of the disclosure, but is not limited thereto.

It should be understood that, without departing from the spirit and scope of the disclosed content, those skilled in the art can make many modifications to the exemplary embodiments described herein. Therefore, this description is not intended and should not be construed as being limited to the given examples, but should be granted the full scope of protection provided by the appended claims and their equivalents. In addition, some features of the present disclosure can be used without using other features. Therefore, in order to explain the principle of the present disclosure, the foregoing description of exemplary or illustrative embodiments is provided instead of limiting, and these embodiments can be modified and arranged.

The inventor has identified light leakage as the cause of CR reduction in QDCF displays by using the polarizer in the "dark state". This disclosure solves this problem by reducing or eliminating light leakage. This disclosure is achieved by incorporating one or more certain technologies into QDCF, which was previously unknown. These technologies are: (1) By collimating the light from the backlight unit (BLU) light source to eliminate the high incident angle of the light in the LCD structure; (2) using a lower height than the O-type polarizer E-type polarizer with incident angle light leakage; (3) Use a compensation film that reduces the high incident angle that causes the polarizer to leak; (4) Use a privacy viewing film that can reduce the high incident angle (causing the polarizer to leak); and (5) ) Add a low refractive index material layer (LIML) on top of the QD layer of the QDCF structure. According to this disclosure, these technologies are incorporated into the QDCF structure alone, or sometimes two or more of them are combined together.

The advantages of the technologies disclosed in this article are that they allow the use of QD (ie, pixelation) in the LC cell, and at the same time have the color gamut advantage of QD, the color angle uniformity of QD (minimum color shift), without compromising CR or brightness. The obtained QDCF will be more efficient than the traditional QDCF LCD.

Since the negative parallax problem found in conventional LCDs is minimized, the use of substantially collimated light in the BLU light source of the LCD allows the use of thicker polarizers. The use of E-type polarizers, compensation films, or privacy viewing films can achieve the use of certain technologies while retaining the advantages of light recycling in the backlight unit (BLU).

Collimating the source light: By collimating the light from the LCD light source, the high incident angle of the light in the LCD structure is eliminated, thereby improving CR. Figure 3 shows the CR improvement trend of QDCF LCD as a function of source light collimation. For these measurements, replace the BLU with a rectangular Lambertian light source. The degree of collimation is given by the half apex angle (in angles) of the cone, which represents the angular range of the source light. Therefore, a half apex angle of 0 degrees represents fully collimated light, where the source light is incident on the LCD plane at a normal angle. The collimation is simulated by confining the light source in the cone with different half-vertex angles in the future. The plot in Figure 3 shows that the beneficial effect of collimation on CR increases exponentially. In our example, the collimation is limited to a half apex angle less than or equal to ±30 degrees, preferably less than or equal to ±20 degrees half apex angle, and more preferably less than or equal to ±15 degrees half apex angle, CR It can range from 1277:1 to 3885:1.

In FIGS. 4A and 4B, the performance of a QDCF with collimated light is compared with the performance of a conventional QDCF with non-collimated light. Figure 4A is the same as Figure 2B. This is a CR drawing of QDCF's non-collimated light (with an angular distribution generated by the modeled BLU unit). This drawing is a "horizontal" angle of view H and a "vertical" angle of view Function of V. CR is a uniform value of ~128:1. Figure 4B is a CR drawing of QDCF, and its taper source collimation is ±15 degrees. CR is also uniform, but the CR value is significantly increased to ~3885:1. The collimation degree of ±15 degrees indicates the half apex angle (in degrees) of the cone, and indicates the degree of angular dispersion of the source light. An example of a collimated light source for BLU that can be applied here is the double-sided turning film disclosed in US Patent No. 7,530,721, the content of which is incorporated herein by reference. Another example was found in T. Ishikawa and Mi Xiang-Dong, P-82: SID 06 DIGEST (2006), "New design of a new type of highly collimated film", the content of which is incorporated herein by reference.

FIG. 5 shows a schematic vertical cross-sectional view of an example of a QDCF LCD panel structure 500 according to the present disclosure. The QDCF LCD panel structure 500 includes a cover glass 595 starting at the farthest point, a back reflector layer 510, a light guide plate (LGP) 520, one or more optical sheets 530, a bottom polarizer 540, and a liquid crystal (LC) layer 550, top polarizer 560, short pass filter (SPF) 570, patterned quantum dot (QD) layer 580, color filter (CF) 590, and cover glass 595. The QD layer 580 and the CF layer 590 are defined as a patterned or pixelated structure of red, green, and blue sub-pixel regions, as shown in FIG. 6. The sub-pixel regions in the CF layer 590 are separated by the black matrix 600 structure. The component layers of the QDCF LCD panel structure 500 are not limited to those (components) shown in FIG. 5. Different embodiments of the QDCF LCD panel can include the QDCF LCD panel and one or more other functional layers of the LCD panel known in the art. Examples of these additional functional layers are brightness enhancement films and diffusers. The locations of some enhancement features of the present disclosure are marked along the left side of the QDCF structure 500 shown in FIG. 5.

Since it is difficult and costly to manufacture an efficient collimated light source (for example, due to limited light recycling and complicated structure manufacturing), other methods for reducing the high incident angle used in QDCF are also disclosed. Referring to the exemplary QDCF structure 500 shown in FIG. 5, according to embodiments, one or both of the top and bottom top polarizers 560, 540 can be E-type polarizers instead of O-type polarizers used in conventional QDCF elements . O-type polarizer (in the uniaxial material corresponding to one dimension in the 3-dimensional directional space) suppresses unusual light waves. However, the E-type polarizer suppresses ordinary optical waves occupying two dimensions in the 3-D direction space and the effect is better. A variety of E-type polarizers can be used. One example is a single-layer E-type polarizer manufactured according to the method described in US Patent No. 5,739,296, the content of which is incorporated herein by reference.

In some embodiments, it is also possible to combine a compensation film designed to eliminate high incident angle light with one or more of the novel enhancements (features) disclosed herein for QDCF into the QDCF structure 500. For example, the compensation film can be combined with the collimated light to be incorporated into the QDCF structure in order to reduce the dark state light leakage in the QDCF structure. US Patent No. 6,995,816 discloses an example of such a compensation film, the content of which is incorporated herein by reference. US Patent No. 6,9956,816 discloses an example of using different combinations of A-plates, C-plates, and biaxial plates as compensation films for polarizer packages. This pair of polarizer packages can be used for the top polarizer 560 and the bottom polarizer 540 in the QDCF structure 500. T. Ishikawa and Mi Xiang-Dong's "Positive O Plate Compensation for Various LCD Modes", SID 06 DIGEST (2006) discloses another example of compensation film, the content of which is incorporated herein by reference. Because the compensation film replaces the top and bottom polarizers 560 and 540, the compensation film and the E-type polarizer will not be incorporated into the QDCF structure at the same time.

In some embodiments, the privacy filter film can also be incorporated into the QDCF structure 500 and combined with one or more of the above-mentioned technologies to reduce dark state light leakage in the QDCF structure. The privacy filter film is a transmissive optical film that uses micro-blinds, and its function is similar to a blind that points directly at the viewer. Therefore, the privacy filter film filters the color filter out of high emission angle light and allows low emission angle light to be transmitted. As shown in FIG. 5, a privacy filter film can be placed between the top polarizer 560 and the short pass filter 570 before the QD layer 580.

5 and 6, according to another embodiment, an improved QDCF structure 500 includes a low refractive index material layer (LIML) layer 585 between the CF layer 590 and the QD layer 580 to minimize or eliminate the TIR effect caused by Loss of light efficiency. When viewed from the top, the QDCF structure 500 includes a series of arrayed pixel areas. FIG. 6 is a schematic vertical cross-sectional view of some related layers in the pixel area of the QDCF structure 500. Figure 6 shows the short-pass filter 570 layer and above the short-pass filter 570 layer up to the cover glass 595 (a schematic cross-sectional view). The pixel area includes the red sub-pixel R, the green sub-pixel G, and the blue sub-pixel B, which are respectively determined by the respective color filters on the QD layer 580 (the red filter 591, the green filter 592, and the blue filter器593) defined. The black matrix 600 barriers are located between the color filters 591, 592, and 593, extend downward through the QD layer 580, and define sub-pixel regions R, G, and B. The collimated blue light (BLU) in the backlight unit is represented by the vertical arrow in the lower part of FIG. 6. The blue light is released by the quantum dots in the R, G, and B sub-pixel regions of the QD layer 580, and is transmitted through the respective color filters 591, 592, 593, and the cover glass 595. As shown in FIG. 6, the LIML layer 585 between the QD layer 580 and the CF layer 590 is pixelated together with the sub-pixel color filters 591, 592, and 593. The black matrix 600 between the sub-pixel color filters 591, 592, and 593 extends down to the LIML layer 585, and the LIML 585 is defined as the sub-regions corresponding to the sub-pixel color filters 591, 592, and 593. LIML 585 improves the light emission efficiency of LCD. This effect is further explained with reference to FIGS. 7A and 7B.

As shown in the schematic diagram of FIG. 7A, in the conventional QDCF structure without the LIML layer, due to the total internal reflection (TIR) and internal recycling in the CF layer 590 and the cover glass 595, the loss from the QD layer 580 has high Lots of light emitting at an angle. Arrow high emission angle of light from the representative of this effect by the QD layer 580 is represented by L _B. High emission angle of light L _B will reach high incidence angle of the cover glass - air boundary 597, so the cover glass - air junction 597 experiences TIR. The cover glass 595 is generally made of high-index glass having a reflection index of about 1.5. Because this light is likely to be absorbed by the color filter in the CF layer 590, most of the light in this light will not leave the LCD panel. Because a typical CF has a transmittance of 80% to 90%, absorption can be achieved by color filters of different colors or the same color.

Referring to FIG. 7B, the QD layer 580 generates light in all directions, and therefore emits light at all possible angles. QD light emitting layer, the emission angle having a normal (i.e., perpendicular to the QD layer 580) or at a low angle light ray is generally L _A emitted from the emission through the cover glass 595 and away from the LCD panel transmission.

When LIML 585 is between QD layer 580 and CF 590, TIR at the boundary between QD layer 580 and LIML 585 recovers the high-angle emission rays L _{B in} QD layer 580 and converts them to leave the high index coverage Low-angle ray L _B 'of glass 595. High angle rays in the QD layer 580 recovered L _B is the result of scattering in the QD layer. Therefore, this increases the overall efficiency of the QDCF structure 500.

In some embodiments, the QDCF LCD panel 500 can further include an additional LIML between the QD layer 580 and the short pass filter layer (SPF) 570. Such additional LIML can help SPF 570 reflect high-angle incident light. This additional LIML does not require pixelation and can be directly pasted onto SPF 570.

Preferably, the interface between the LIML 585 and the QD layer 580 should not introduce too much scattering. Preferably, in order to control the light scattering at the interface between LIML 585 and QD layer 580, the flatness of the interface between LIML and QD layer should be controlled so that the scattering has a large enough angle to be at the cover glass-air interface 597 The light energy of the rays that encounter TIR is minimized. The volume scattering from LIML 585 and the surface scattering at the interface 587 between LIML 585 and QD layer 580 are advantageously controlled so that the scattering has a large enough angle to thereby encounter TIR at the interface 597 between the cover glass and the air. The angle of light energy is minimized. The characteristic of the scattering of the film is the haze (in transmission), considering the volume and surface scattering. The flatness of the interface 587 between the LIML 585 and the QD layer 580 is controlled to limit the haze value measured according to the ASTM D1003 standard to be less than or equal to 50%, preferably less than or equal to 30%, and most preferably less than or Equal to 5%.

The improvement degree of LIML in the luminous efficiency of QDCF depends on the reflection index of LIML 585. Any material with a reflection index lower than the refractive index of the CF and QD layers 580 can be used as LIML 585. The greater the difference in refractive index between the QD layer 580 and the LIML 585, the better the performance of the LIML. This relationship of refractive index means that the QD layer 580 can be manufactured with a reflection index higher than 1.5 (the reflection index of the cover glass 595), which will provide a larger possible refractive index window for LIML materials. The cover glass 595 generally has a reflection index of 1.5.

The calculation (result) shows that as the reflection coefficient of LIML 585 decreases from 1.5 to 1.0, the luminous efficiency of QDCF will gradually increase. This data is plotted in Figure 8. When the reflection index of LIML changes from 1.5 to 1.0 on the x-axis, the relative luminous efficiency changes from 0.65 to about 1.025. According to the embodiment, LIML having a refractive index value in the range of 1.5 to 1.0 (inclusive) is satisfactory. According to some embodiments, the reflection index of LIML is in the range of 1.4 to 1.0, preferably in the range of 1.3 to 1.0, more preferably in the range of 1.2 to 1.0.

Werdehausen et al. revealed some examples of nano-porous materials with low index and low scattering properties that can be used in LIML, "Design rules for customizable materials based on nanocomposites," Optical Materials Express 8 (11 ), 3456 (2018). The following table provides other examples of possible materials for LIML 585: material Reflection index example polymer 1.3-1.4 Acrylate, propionate, acetate, and silicone. Porous materials 1.07-1.16 Masato Yamaguchi, Hiroyuki Nakayama, Kazuhiro Yamada, and Hiroaki Imai describe porous materials with reflectance as low as 1.07, "ultra-low reflection index coatings composed of mesoporous silica nanoparticles", 34( 13), 2009). An example is silicon dioxide with pores. The nanoparticle-polymer composite forms a hydrophobic film above the decomposition temperature, and its refractive index is as low as 1.048. It is found in Venumadhav Korampally, Minseong Yun, Thiruvengadathan Rajagopalan, Purnendu K Dasgupta, Keshab Gangopadhyay, and Shubhra Gangopadhyay (Journal of Nano Technology, No. Volume 20, Issue 42, 2009). One example is polymethylsilsesquioxane nanoparticles. Ultra-low reflection index (as low as 1.04), crack-free thick coating (thickness to 3.6 microns) based on organosilicate nanoparticle (NPO) network, developed by Venumadhav Korampally, Maruf Hossain, for example, Minseong Yun, Keshab Gangopadhyay , Luis Polo-Parada, and Shubhra Gangopadhyay (The 12th International Conference on Small Systems in Chemistry and Life Sciences, October 12-16, 2008, San Diego, California, USA). An example is the organosilicate nanoparticle network. Mesoporous silica films with a refractive index of 1.14 used in 2D photonic crystal waveguide systems, such as those in Frank Marlow, Denan Konjhodzic, Helmut Bretinger, and Li Hongliang (Progress in Solid State Physics, 2006, Vol. 45/2006, 149 -161).

The black matrix located between R, G, and B blocks light that has nothing to do with the display, otherwise this light will appear on the viewing side of the QDCF panel, thereby reducing the overall CR. Generally, the black matrix material reflects the incident light to achieve the black matrix blocking the light that does not meet the requirements. The conventional black matrix contains a reflective metal layer, such as chromium. Although most of the light reflected by the black matrix cannot enter the final image, some of it will pass through the scattering and reflection at several optical junctions inside the LCD panel structure and finally affect the final image, thereby reducing the contrast. That is, CR decreases. Therefore, in the exemplary QDCF panel structure, the black matrix is coated with a layer of light absorbing material (such as polymer or oxide) to substantially reduce the harmful reflection of the black matrix. In other examples, the black matrix is made of photoresist resin in which melanin has been dispersed to reduce reflectivity.

Referring to FIG. 9, according to an embodiment of the present disclosure, the black matrix structure 600 is configured to have inclined sides and is partially reflective, which also independently improves the light emission efficiency of the QDCF structure. Here, as mentioned above, the "partially reflective" feature only means that the black matrix includes a reflective surface exposed to the QD layer 580, while the remaining surfaces of the black matrix are conventional light-absorbing or non-reflective surfaces. FIG. 9 is a schematic diagram of an example of such a black matrix structure 600. The black matrix 600 is a barrier between the color filters in the color filter layer 590, and extends downward through the QD layer 580, thereby defining sub-pixel regions R, G, and B (see FIG. 6). The black matrix 600 includes sides 602 inclined at an angle α, so in the plan sectional view shown in FIG. 9, the black matrix 600 has a substantially trapezoidal shape, and the black matrix 600 is narrower at the top near the cover glass 595 than at the bottom. In addition, the side 602 facing the CF layer 590 and the QD layer 580 is reflective, while the remaining side facing the top 603 of the cover glass 595 is non-reflective. The inclination angle α of the side 602 is 45 degrees, and the deviation is less than or equal to +/-20 degrees, preferably less than or equal to +/-10 degrees, and more preferably less than or equal to +/-5 degrees. In the QDCF element using blue source light, the inclined side 602 causes the red and green light generated in the QD layer in the QD layer 580 to be "guided" or "limited" to be directed toward the viewer again. The blue source light can be reflected by the black matrix 600 toward the viewer and absorbed by the color filter (RG), or can be absorbed by the black matrix.

According to some embodiments, a QDCF LCD device 500 is disclosed, including: a cover glass 595; a back reflector layer 510; a liquid crystal panel layer 550 between the cover glass and the back reflector layer; between the liquid crystal panel layer 550 and the back reflector layer The backlight unit 520 (including the blue LED light source and the light guide plate) between 510, the backlight unit is configured to generate image forming light for the liquid crystal panel layer; the patterned quantum dot layer 580 between the cover glass and the liquid crystal panel layer In the color filter layer 590 between the cover glass and the quantum dot layer, the color filter 590 and the quantum dot layer 580 are combined and configured to convert the wavelength of the image forming light from the backlight unit and through the liquid crystal panel 550 to The color is formed; the bottom polarizer layer 540 is located between the liquid crystal panel layer 550 and the backlight unit 520; the top polarizer layer 560 is provided between the liquid crystal panel layer and the quantum dot layer. In this embodiment of the QDCF LCD device, one of the following enhancement features is also incorporated: (a) LIML 585 disposed between the color filter layer 590 and the quantum dot layer 580; (b) configured to produce A backlight unit for collimated image forming light of the liquid crystal panel layer; (c) one or both of the bottom polarizer 540 and the top polarizer 560 are made of E-type polarizer material; (d) the bottom polarizer 540 and top polarizer 560 are respectively made of one or more compensation films including A plate, C plate, and biaxial plate; (e) privacy filter arranged between the top polarizer 560 and the quantum dot layer 580器膜。 Film.

In other embodiments, the QDCF LCD device 500 includes LIML 585 between the color filter layer 590 and the quantum dot layer 580, and also incorporates one or more of the following enhancement features: (a) Bottom polarizer 540 and top One or both of the polarizers 560 are made of E-type polarizer materials; (b) a backlight unit configured to generate collimated image forming light for the liquid crystal panel layer; (c) bottom polarizer 540 and top The polarizers 560 are respectively made of compensation films including A plate, C plate, and biaxial plate; (d) a privacy filter film disposed between the top polarizer 560 and the quantum dot layer 580.

Although the embodiments of the present disclosure have been described, it should be understood that the described embodiments are only exemplary, and when all equal scopes are assigned, the scope of the present invention is limited only by the appended claims, from In close reading, those who are familiar with the art will naturally undergo many changes and modifications.

500: QDCF LCD panel structure 510: rear reflector layer 520: Rear reflector layer light guide plate/LGP 530: Optical sheet 540: bottom polarizer 550: LCD/LC 560: Top polarizer 570: Short pass filter/SPF 580: Patterned quantum dots/QD 585: Low refractive index material layer/LIML 587: Boundary 590: Color filter/CF 591: Red filter 592: Green color filter 593: Blue filter 595: cover glass 597: Cover glass-air junction 600: black matrix 602: side

These figures are provided for the purpose of illustration, and it should be understood that the embodiments disclosed and discussed herein are not limited to the arrangements and means shown.

Figures 1A and 1B show the angular dependence of light transmission through a pair of crossed polarizers when the pixels are "on" and "off", respectively.

Figure 2A is a plot of the contrast ratio of a conventional LCD.

Figure 2B is a plot of the contrast ratio of the conventional QDCF LCD.

Figure 3 is a plot of the improvement trend of the QDCF contrast ratio as a function of source light collimation.

Figure 4A is a plot of the contrast ratio of a conventional QDCF LCD with non-collimated light.

Fig. 4B is a plot of the contrast ratio of the QDCF LCD with collimated light.

FIG. 5 is a schematic diagram of an exemplary QDCF LCD structure according to the disclosure.

FIG. 6 is a schematic cross-sectional view of a pixel area in a QDCF LCD structure according to the present disclosure.

FIG. 7A is a schematic cross-sectional view of a part of the pixel area in the QDCF structure of the prior art.

FIG. 7B is a schematic cross-sectional view of a part of a pixel area in a QDCF structure with LIML according to an embodiment of the present disclosure.

Figure 8 is a plot of LIML's relative luminous efficiency versus refractive index.

FIG. 9 is a schematic diagram of an example of a black matrix structure according to an embodiment of the disclosure.

Although this description can include details, these should not be construed as limitations on the scope, but as a description of the features of specific embodiments.

Domestic deposit information (please note in the order of deposit institution, date and number) no Foreign hosting information (please note in the order of hosting country, institution, date and number) no

500: QDCF LCD panel structure

510: rear reflector layer

520: Rear reflector layer light guide plate/LGP

530: Optical sheet

540: bottom polarizer

550: LCD/LC

560: Top polarizer

570: Short pass filter/SPF

580: Patterned quantum dots/QD

590: Color filter/CF

595: cover glass

600: black matrix

Claims (34)

A quantum dot color filter (QDCF) liquid crystal display (LCD) device, including: A cover glass; A rear reflector layer; A liquid crystal panel layer between the cover glass and the back reflector layer; A backlight unit between the liquid crystal panel layer and the back reflector, the backlight unit being configured to generate an image forming light to the liquid crystal panel layer; A quantum dot layer between the cover glass and the liquid crystal panel layer; A color filter layer between the cover glass and the quantum dot layer, the color filter and the quantum dot layer are combined and configured to form a color by converting a wavelength of the collimated image forming light; A bottom polarizer layer located between the liquid crystal panel layer and the backlight unit; A top polarizer layer located between the liquid crystal panel layer and the quantum dot layer; and Further include one or more of the following: (a) A low refractive index material layer (LIML) between the color filter layer and the quantum dot layer; (b) A backlight unit configured to generate collimated image forming light to the liquid crystal panel layer; (c) One or both of the bottom polarizer and the top polarizer include an E-type polarizer material; (d) The bottom polarizer and the top polarizer each include a compensation film, and the compensation film includes one or more of an A plate, a C plate, and a biaxial plate; and (e) A privacy filter film between the top polarizer and the quantum dot layer. The QDCF LCD device according to claim 1, including: (a) and the ASTM D1003 haze value of the interface between the LIML and the quantum dot layer is less than or equal to 50%. The QDCF LCD device according to claim 2, wherein the ASTM D1003 haze value of the interface between the LIML and the quantum dot layer is less than or equal to 30%. The QDCF LCD device according to claim 2, wherein the ASTM D1003 haze value of the interface between the LIML and the quantum dot layer is less than or equal to 5%. The QDCF LCD device according to claim 1, including (a) and the refractive index value of the LIML is in a range of 1.5 to 1.0. The QDCF LCD device according to claim 5, wherein the refractive index value of the LIML is in a range of 1.4 to 1.0. The QDCF LCD device according to claim 5, wherein the refractive index value of the LIML is in a range of 1.3 to 1.0. The QDCF LCD device according to claim 5, wherein the refractive index value of the LIML is in a range of 1.2 to 1.0. The QDCF LCD device according to claim 1, comprising (a); further comprising: a short-pass filter between the quantum dot layer and the top polarizer; and between the quantum dot layer and the short-pass filter An extra LIML between the optical device layers. The QDCF LCD device according to claim 1, comprising (e); further comprising a short-pass filter between the quantum dot layer and the top polarizer; and the privacy filter film is located on the top polarizer Between the filter and the short-pass filter layer. The QDCF LCD device according to claim 1, wherein the collimated imaging light generated by the backlight unit has a half apex angle less than or equal to ±30 degrees. The QDCF LCD device according to claim 1, wherein the collimated imaging light generated by the backlight unit has a half apex angle less than or equal to ±20 degrees. The QDCF LCD device according to claim 1, wherein the collimated imaging light generated by the backlight unit has a half apex angle less than or equal to ±15 degrees. The QDCF LCD device according to claim 1, wherein the color filter layer and the quantum dot layer together include a plurality of pixel areas, and each pixel area includes a red sub-pixel area, a green sub-pixel area, and a blue Sub-pixel area; and The device further includes a black matrix barrier structure that extends through the color filter layer and the quantum dot layer to separate two adjacent sub-pixel regions, wherein the black matrix includes and The side surface where the color filter layer and a quantum dot layer contact; The side surfaces of the black matrix are inclined at an angle of 45 degrees, and the inclination has a deviation less than or equal to ±20 degrees. The QDCF LCD device according to claim 14, wherein the sides are inclined at an angle of 45 degrees, and the inclination has a deviation less than or equal to ±10 degrees. The QDCF LCD device according to claim 14, wherein the side surfaces are inclined at an angle of 45 degrees, and the inclination has a deviation less than or equal to ±5 degrees. The QDCF LCD device according to claim 14, wherein the side surfaces and the bottom surface of the black matrix are reflective. A quantum dot color filter (QDCF) liquid crystal display (LCD) device, including: A cover glass; A rear reflector layer; A liquid crystal panel layer between the cover glass and the back reflector layer; A backlight unit between the liquid crystal panel layer and the back reflector, the backlight unit being configured to generate an image forming light to the liquid crystal layer; A quantum dot layer between the cover glass and the liquid crystal panel layer; A color filter layer between the cover glass and the quantum dot layer. The color filter and the quantum dot layer are combined to form light by converting a collimated image from the backlight unit and passing through the liquid crystal panel A wavelength of to form the color; A bottom polarizer layer located between the liquid crystal panel layer and the backlight unit; A top polarizer layer located between the liquid crystal panel layer and the quantum dot layer; Providing a low refractive index material layer (LIML) between the color filter layer and the quantum dot layer; and Further include one or more of the following: (a) One or both of the bottom polarizer and the top polarizer are made of E-type polarizer materials; (b) A backlight unit configured to generate collimated image forming light to the liquid crystal panel layer; (c) The bottom polarizer and the top polarizer are each made of compensation film, which includes one or more of A plate, C plate, and biaxial plate; and (d) Provide a privacy filter film between the top polarizer and the quantum dot layer. The QDCF LCD device according to claim 18, wherein the ASTM D1003 haze value of the interface between the LIML and the quantum dot layer is less than or equal to 50%. The QDCF LCD device according to claim 19, wherein the ASTM D1003 haze value of the interface between the LIML and the quantum dot layer is less than or equal to 30%. The QDCF LCD device according to claim 19, wherein the ASTM D1003 haze value of the interface between the LIML and the quantum dot layer is less than or equal to 5%. The QDCF LCD device according to claim 18, wherein the refractive index value of the LIML is in a range of 1.5 to 1.0. The QDCF LCD device according to claim 22, wherein the refractive index value of the LIML is in a range of 1.4 to 1.0. The QDCF LCD device according to claim 22, wherein the refractive index value of the LIML is in a range of 1.3 to 1.0. The QDCF LCD device according to claim 22, wherein the refractive index value of the LIML is in a range of 1.2 to 1.0. The QDCF LCD device according to claim 18, further comprising a short-pass filter between the quantum dot layer and the top polarizer; and An additional LIML is further included between the quantum dot layer and the short-pass filter layer. The QDCF LCD device according to claim 18, comprising (d); further comprising a short-pass filter between the quantum dot layer and the top polarizer; and the privacy filter film is located on the top polarizer Between the filter and the short-pass filter layer. The QDCF LCD device according to claim 18, wherein the collimated imaging light generated by the backlight unit has a half apex angle less than or equal to ±30 degrees. The QDCF LCD device according to claim 18, wherein the collimated imaging light generated by the backlight unit has a half apex angle less than or equal to ±20 degrees. The QDCF LCD device according to claim 18, wherein the collimated imaging light generated by the backlight unit has a half apex angle less than or equal to ±15 degrees. The QDCF LCD device according to claim 18, wherein the color filter layer and the quantum dot layer together include a plurality of pixel areas, and each pixel area includes a red sub-pixel area, a green sub-pixel area, and a blue Sub-pixel area; and The device further includes a black matrix barrier structure that extends through the color filter layer and the quantum dot layer to separate two adjacent sub-pixel regions, wherein the black matrix includes and The color filter layer and the side surface of the quantum dot layer in contact; The side surfaces of the black matrix are inclined at an angle of 45 degrees, and the inclination has a deviation less than or equal to ±20 degrees. The QDCF LCD device according to claim 31, wherein the side surfaces are inclined at an angle of 45 degrees, and the inclination has a deviation less than or equal to ±10 degrees. The QDCF LCD device according to claim 31, wherein the side surfaces are inclined at an angle of 45 degrees, and the inclination has a deviation less than or equal to ±5 degrees. The QDCF LCD device according to claim 31, wherein the side surfaces and the bottom surface of the black matrix are reflective.

Images