CN113272728A

CN113272728A - Enhanced quantum dots on color filter LCD

Info

Publication number: CN113272728A
Application number: CN201980088096.2A
Authority: CN
Inventors: 韩松峰; 石川智弘; F·D·基瑟列夫; 迈克尔·梅尔尼克
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2018-11-30
Filing date: 2019-11-21
Publication date: 2021-08-17
Also published as: TW202030535A; JP2022510940A; WO2020112470A9; WO2020112470A1; KR20210087543A

Abstract

Disclosed is a quantum dot on a color filtered (QDCF) LCD device having certain combinations of enhancement features that enhance contrast ratio by eliminating or minimizing high angle incident light within the LCD stack.

Description

Enhanced quantum dots on color filter LCD

Cross Reference to Related Applications

This application claims benefit of priority from U.S. patent provisional applications nos. 62/798607 and 62/773449, filed on 2019, 30/1 and 2018, 11/30/11, respectively, pursuant to 35 u.s.c. 119, the respective contents of each of which are incorporated herein by reference in their entirety.

Technical Field

This disclosure relates to enhanced quantum dots on color filter LCDs.

Background

The Liquid Crystal Display (LCD) industry is seeking solutions to increase the efficiency and improve the color gamut (color content of the display) of LCDs in order to compete with Organic Light Emitting Display (OLED) products. Conventional LCDs lag behind OLEDs, especially in terms of color gamut performance. The use of Quantum Dots (QDs) in liquid crystal displays improves the color gamut performance of the liquid crystal display; such improvements have in fact been apparent in LCD designs, where QD film assemblies are used in backlight units (BLU), i.e. light sources providing light to fill the active matrix of the pixels by the Liquid Crystals (LC) of the LCD pixilated panel. In these BLU designs, the blue LED light is coupled to a Light Guide Plate (LGP) and is extracted from the LGP in the direction of the LCD pixilated panel. The guided blue light then encounters the QDs, which absorb a portion of the blue light and emit light in the green and red spectra. The resulting light in the red, green and blue spectra provides a white light source for the LCD pixilated panel.

In other designs, the QD material is placed directly in the corresponding individual pixels within the LCD pixilated panel. This design not only guarantees a larger color gamut, but also potentially replaces the Color Filters (CF) that define the individual pixel colors in a conventional (QD-free) LCD design. Such a design is referred to as a "quantum dot on color filter" (QDCF) design. In the QDCF design, the QD pixels are placed after (where) the light encounters two polarizers that are part of the LCD, which together with the LC manipulate the polarization of the light.

Even a perfect pair of polarizers will cause light incident upon them to leak in a direction "not normal to the plane of the sheet polarizer" (normal to the surface of the emitting assembly). Fig. 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. Fig. 1A and 1B show the light transmission through a pair of crossed polarizers as a function of viewing angle (normal viewing angle is in the center of the figure) in the "on" and "off" states of the pixel, respectively. The indices x-axis and y-axis are H and V, representing the "horizontal" and "vertical" angles (in degrees) from the normal viewing angle (center of the figure) in the horizontal and vertical directions, respectively. Fig. 1A shows light emitted from a conventional LCD in an on state transmitted through a pair of crossed polarizers. High angle rays cause a sharp drop in Contrast Ratio (CR) at high angles of incidence (or viewing angles). Therefore, a darker area near the periphery of fig. 1A, near the 90 degree viewing angle, shows a lower transmission at higher viewing angles. FIG. 1B shows light emitted from an LCD in the off state (i.e., light leakage) passing through a pair of crossed polarizers.

Comparing light emission between the on and off states shown in fig. 1A and 1B, in a conventional LCD, high angle light rays cause a sharp drop in Contrast Ratio (CR) at high incident angles (or viewing angles). CR measures the ratio of the light of the LCD in the on state to the light of the LCD in the off state. Ideally, the off state should be as dark as possible for all angles of incidence, and is therefore referred to as the dark state. CR is very sensitive to light in the dark state (denominator). Even with a small amount of light in the dark state, CR is significantly reduced.

In the simulations of QDCF, the inventors observed that the sharp drop in CR was a result of light leakage through the polarizer at high viewing angles. In conventional LCDs, the leaked light remains directed towards high viewing angles, while in QDCF this light is significantly scattered, including the blue light source. This means that the leaked light is also directed towards angles close to the normal viewing angle, while increasing the value of light in the denominator defined by the normal (and other directions) CR, effectively averaging CR across various viewing angles. Such averaging undesirably reduces CR by a large amount.

Fig. 2A is a CR plot of an example of a conventional LCD, and fig. 2B is a CR plot of a conventional QDCF. The x-axis and y-axis H and V are labeled to represent the "horizontal" and "vertical" angles from the normal viewing angle (center of the figure) in the horizontal and vertical directions. Fig. 2A shows CR of the conventional LCD. CR of a conventional LCD is calculated as the normal viewing angle (both horizontal and vertical angles are 0 degrees)

1, represented by the peak at the center of the plot, but decreases significantly with increasing horizontal and vertical viewing angles. Therefore, CR in the conventional LCD is significantly deteriorated if the viewer does not observe the LCD at a normal viewing angle. This provides a very non-uniform viewing experience for the viewer. Fig. 2B shows CR of the QDCF LCD. The CR of QDCF LCDs is more uniform, but is very low for the viewer, approximately 128: 1. a low CR may result in a reduced image quality for the viewer. Even though the CR at normal viewing angles can have values of several kiloseconds (a vertically aligned LC mode display can have

CR value of) of the organic compound, CR still decreases to a high viewing angle<10。

QD-based displays generally provide higher color accuracy and a wider color gamut. Current technology converts blue light to white using a blue LED for backlighting and a QD film using a mixture of red and green QDs inside a backlight unit (BLU). Another concept of QDCF allows to provide a better color gamut because the conversion is done in the color filters (CF's) instead of in the BLU. In these designs, a short pass filter is located between the QD layer/color filter layer and the BLU. In another approach disclosed in U.S. patent application publication No. US2017/0153366, the contents of which are incorporated herein by reference, a band-cut filter is used to filter out blue light after conversion. Schemes using uv light from backlights and blue QDs are also described in US 2017/0153366.

Another problem observed with these designs is that, in addition to the lower CR, it is due to total internal reflection(TIR), light of high exit angle will also be confined (trap) inside the cover glass. In conventional LCD designs, the light output is typically concentrated at some limited output angle, and hence TIR is not a limiting factor. However, in QDCF designs, the QD layer re-emits light at various angles, so significant light undergoes TIR. Light reflected back by TIR may be absorbed by Color Filters (CF) of different colors or the same color (a typical absorbing CF has

Transmission rate) resulting in a significant reduction in the amount of light ultimately emitted by the LCD.

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

Disclosure of Invention

According to an embodiment of the present disclosure, a QDCF LCD device is disclosed. A Quantum Dot Color Filter (QDCF) Liquid Crystal Display (LCD) device, comprising: a cover glass; a back 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 configured to generate 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 quantum dot layer in combination configured to form a color by converting a wavelength of image forming light from the backlight unit and penetrating through the liquid crystal panel; a bottom polarizer layer between the liquid crystal panel layer and the backlight unit; a top polarizer layer between the liquid crystal panel layer and the quantum dot layer; and further comprising one or more of the following enhanced features:

a low refractive index material layer (LIML) provided between the color filter layer and the quantum dot layer;

a backlight unit configured to generate collimated image forming light to the liquid crystal panel layer;

one or both of the bottom polarizer and the top polarizer are made of E-type polarizer material;

the bottom polarizer and the top polarizer are each made of a compensation film comprising one or more of an a plate, a C plate, and a biaxial plate; and

a privacy filter is provided between the top polarizer and the quantum dot layer.

According to some embodiments, a QDCF LCD device includes a backlight unit configured to generate image forming light to a liquid crystal panel layer, and a LIML provided between a color filter layer and a quantum dot layer; and further comprising one or more of the following enhanced features:

It is to be understood that both the foregoing general description and the following detailed description present embodiments of the disclosure, and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings herein illustrate different embodiments of the disclosure and, together with the description, serve to explain the principles and operations of the claimed subject matter.

Drawings

These figures are provided for illustrative purposes, and it is to be understood that the embodiments disclosed and discussed herein are not limited to the arrangements and instrumentality shown.

Fig. 1A and 1B show the angular dependence of light transmission through a pair of crossed polarizers when the pixel is "on" and "off," respectively.

Fig. 2A is a plot of contrast ratio for a conventional LCD.

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

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

Fig. 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 a QDCF LCD with collimated light.

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

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

Fig. 7A is a schematic cross-sectional view of a portion of a pixel region in a prior art QDCF structure.

Fig. 7B is a schematic cross-sectional view of a portion of a pixel region in a QDCF structure with LIML, according to an embodiment of the present disclosure.

Fig. 8 is a plot of LIML relative luminous efficiency versus refractive index.

Fig. 9 is a schematic view of an example of a black matrix structure according to an embodiment of the present disclosure.

Although this description may contain details, these should not be construed as limitations on the scope, but rather as descriptions of features that may be specific to particular embodiments.

Detailed Description

Various embodiments of luminescent coatings and devices are described with reference to the accompanying drawings, wherein like components have been given like reference numerals to facilitate understanding.

It should also be understood that terms such as "top," "bottom," "outward," "inward," and the like are words of convenience and are not to be construed as limiting terms unless otherwise specified. In addition, whenever a group is described as including at least one of a set of elements and combinations thereof, the group can include, consist essentially of, or consist of the combination of these elements, either individually or any number of the elements carried or the combination of these tuples.

Similarly, whenever a group is described as consisting of at least one element of a group of elements or a combination thereof, the group can consist of any number of the elements carried or combinations of the elements, individually. Unless otherwise specified, when a range of values is specified, the upper and lower limits of that range are included. As used herein, the indefinite article "a" or "an" and its corresponding definite article "the" mean at least one, or one or more, unless otherwise indicated.

Those skilled in the art will recognize that many modifications may be made to the described embodiments while still obtaining the beneficial results of the disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the described features without using other features. Thus, those who work in the art will recognize that many modifications and adaptations are possible and can even be desirable in certain circumstances and are a part of the disclosure. Accordingly, the following description is provided to illustrate the principles of the present disclosure, but is not limited thereto.

It should be understood that numerous modifications to the exemplary embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the disclosure. Accordingly, this description is not intended to, and should not be construed as, limited to the examples given, but is to be accorded the full scope afforded by the appended claims and equivalents thereof. In addition, some features of the present disclosure can be used without the use of other features. Thus, the foregoing description of exemplary or illustrative embodiments is provided for the purpose of illustrating the principles of the present disclosure and is not to be taken in a limiting sense, and the embodiments are capable of modification and arrangement.

The inventors have identified light leakage as a cause of reduced CR in QDCF displays by polarizers in the "dark state". The present disclosure addresses this problem by reducing or eliminating light leakage. The present disclosure is achieved by incorporating one or more certain techniques into the QDCF, which was previously unknown. These techniques (1) eliminate high angles of incidence of light within the LCD structure by collimating light from a backlight unit (BLU) light source; (2) using an E-type polarizer with lower high incident angle light leakage than an O-type polarizer; (3) using a compensation film that reduces the high angle of incidence that causes polarizer leakage; (4) use of privacy viewing films that can reduce high incidence angles (causing polarizer leakage); and (5) adding a low refractive index material layer (LIML) over the QD layer of the QDCF structure. These techniques are incorporated into the QDCF structure individually or, sometimes, two or more of them are combined together in accordance with the present disclosure.

An advantage of the techniques disclosed herein is that they allow for the use of QDs within an LC cell (i.e., pixelation) while enjoying the gamut advantages of QDs, the color angle uniformity of QDs (minimal color shift), without compromising CR or brightness. The QDCF obtained will be more efficient than the conventional QDCF LCD.

The use of substantially collimated light in the BLU light sources of an LCD allows the use of thicker polarizers since the negative parallax problem found in conventional LCDs is minimized. The use of E-type polarizers, compensation films, or privacy viewing films may enable the use of certain techniques while retaining the advantages of light recycling in backlight units (BLU).

Collimating the source light: high angles of incidence of light within the LCD structure are eliminated by collimating the light from the LCD light source, thereby improving CR. Fig. 3 shows the CR improvement trend of QDCF LCDs as a function of source light collimation. For these measurements, the BLU was replaced with a rectangular lambertian light source. The collimation is given in the half apex angle (in degrees) of the cone, representing the angular range of the source light. Thus, a half apex angle of 0 degrees represents fully collimated light, with the source light incident on the LCD plane at a normal angle. Collimation is simulated by confining the light source within cones with different half-apex angles. The plot of fig. 3 shows that the beneficial effect of collimation on CR is exponentially increasing. In our example, limiting the degree of collimation to less than or equal to ± 30 degrees at half apex angle, preferably less than or equal to ± 20 degrees at half apex angle and more preferably less than or equal to ± 15 degrees at half apex angle, CR can be within a range from 1277: 1 to 3885: 1, in the above range.

In fig. 4A and 4B, the performance of the QDCF with collimated light is compared to the performance of the conventional QDCF with non-collimated light. FIG. 4A is the same as FIG. 2B, which is a CR plot of the uncollimated light (with the angular distribution produced by the modeled BLU unit) of QDCF as a function of viewing angle H for "horizontal" angles and V for "vertical" angles. CR is uniform

A value of 1. Fig. 4B is a CR plot of QDCF with a taper source collimation of ± 15 degrees. CR is also uniform, but the CR value is significantly improved

1. The degree of collimation is ± 15 degrees, representing the half-angle of the cone (in degrees), representing the degree of angular dispersion of the source light. An example of a collimated light source for a BLU that can be applied herein is the double-sided turning film disclosed in U.S. patent No. 7,530,721, the contents of which are incorporated herein by reference. Another example is found in T.Ishikawa and Mi Xiang-Dong, P-82: SID 06DIGEST (2006), "new design of novel highly collimated films," the contents of which are incorporated herein by reference.

Fig. 5 shows a schematic vertical cross-sectional illustration of an example of a QDCF LCD panel structure 500 according to the present disclosure. The QDCF LCD panel structure 500 includes, starting at the farthest cover glass 595, a back reflector layer 510, a Light Guide Plate (LGP)520, one or more optical sheets 530, a bottom polarizer 540, a Liquid Crystal (LC) layer 550, a top polarizer 560, a Short Pass Filter (SPF)570, a patterned Quantum Dot (QD) layer 580, a Color Filter (CF)590, and a 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 a black matrix 600 structure. The component layers of the QDCF LCD panel structure 500 are not limited to those (components) shown in fig. 5. Various embodiments of the QDCF LCD panel can include other functional layer(s) of the QDCF LCD panel and LCD panel as is conventional in the art. Examples of these additional functional layers are brightness enhancement films and diffusers. The location of certain enhanced features of the present disclosure are marked along the left side of the QDCF structure 500 shown in fig. 5.

Since it is somewhat difficult and costly to manufacture efficient collimated light sources (e.g., due to limited recycling of light and complex fabrication of the structure), other methods of reducing the high incident angles used in QDCF are also disclosed. Referring to the exemplary QDCF structure 500 shown in fig. 5, according to an embodiment, 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 assemblies. The O-polarizer (in a uniaxial material corresponding to one dimension in the 3-dimensional direction space) suppresses extraordinary light waves. However, the E-type polarizer suppresses ordinary optical waves occupying two dimensions in a 3-D directional space and the effect will be better. A variety of E-type polarizers can be used. One example is a single layer E-type polarizer made according to the method described in U.S. patent No. 5,739,296, the contents of which are incorporated herein by reference.

In some embodiments, compensation films designed to eliminate high angle of incidence light can also be combined with one or more of the novel enhancements (features) for QDCF of the present disclosure into QDCF structure 500. For example, a compensation film can be incorporated into the QDCF structure in combination with collimated light to reduce dark state light leakage in the QDCF structure. Examples of such compensation films are disclosed in U.S. patent No. 6,995,816, the contents of which are incorporated herein by reference. U.S. patent No. 6,9956,816 discloses an example of a polarizer package using a combination of different a-plates, C-plates, and biaxial plates as compensation films. This pair of polarizer packages can be used for the top polarizer 560 and the bottom polarizer 540 in the QDCF structure 500. Another example of a compensation film is disclosed in SID 06DIGEST (2006), the contents of which are incorporated herein by reference, in "positive O-plate compensation various LCD modes" by ishikawa and Mi Xiang-Dong. Because the compensation films replace the top and

bottom polarizers

560 and 540, the compensation films and the E-type polarizer are not incorporated into the QDCF structure at the same time.

In some embodiments, privacy filters can also be incorporated into the QDCF structure 500 in combination with one or more of the techniques described above to reduce dark state light leakage in the QDCF structure. The privacy filter is a transmissive optical film that employs micro-louvers and functions similarly to a louver that is directed directly toward the viewer. Thus, the privacy filter filters out the color filters from high emission angle light and allows low emission angle light to be transmitted. As shown in fig. 5, a privacy filter can be placed between the top polarizer 560 and the short pass filter 570 before the QD layer 580.

Referring to fig. 5 and 6, according to another embodiment, an improved QDCF structure 500 includes a Low Index Material Layer (LIML) layer 585 between a CF layer 590 and a QD layer 580 to minimize or eliminate light efficiency loss due to TIR effects. When viewed from the top, the QDCF structure 500 includes a series of arranged pixel regions, and fig. 6 is a schematic vertical cross-sectional illustration of some relevant layers in the pixel region of the QDCF structure 500. Fig. 6 shows a (schematic cross-sectional view of) the layer of short-pass filter 570 and over the layer of short-pass filter 570 up to a cover glass 595. The pixel region includes red, green and blue sub-pixels R, G and B, respectively defined by respective color filters (red, green and

blue color filters

591, 592 and 593) on the QD layer 580. A black matrix 600 barrier is positioned between

color filters

591, 592, and 593, extending down through QD layer 580, defining subpixel areas R, G and B. The collimated Blue Light (BLU) in the backlight unit is indicated by the vertical arrow in the lower part of fig. 6. Blue light is released by the R, G of the QD layer 580 and the quantum dots in the B sub-pixel region, and is transmitted through each

individual color filter

591, 592, 593 and cover glass 595. As shown in fig. 6, the LIML layer 585 between the QD layer 580 and the CF layer 590 is pixelated along 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, defining the LIML585 as sub-regions corresponding to the

sub-pixel color filters

591, 592, and 593. The LIML585 improves light emission efficiency of the LCD. This effect is further illustrated with reference to fig. 7A and 7B.

As shown in the schematic illustration of fig. 7A, in the conventional QDCF structure without the LIML layer, much of the light with high emission angles from the QD layer 580 is lost due to Total Internal Reflection (TIR) and internal recycling within the CF layer 590 and the cover glass 595. This effect is represented by the arrow L representing the high emission angle light from the QD layer 580_BAnd (4) showing. High emission angle light L_BWill reach the cover glass-air interface 597 at a high angle of incidence and thus undergo TIR at the cover glass-air interface 597. The cover glass 595 is generally made of high index glass having a reflectivity of about 1.5. Since these rays are likely to be reflected by the CF layer 590The color filters absorb most of these rays of light without leaving the LCD panel. Since a typical CF has a transmittance of 80% to 90%, the 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 thus emits light at all possible angles. Of the light emitted by the QD layer, having a normal emission angle (i.e., orthogonal to the QD layer 580) or generally at L_AThe emitted low angle emitted light rays will be transmitted through the cover glass 595 and exit the LCD panel.

TIR at the boundary between QD layer 580 and LIML585 recovers high angle emitted rays L within QD layer 580 when LIML585 is between QD layer 580 and CF 590_BAnd converts them into low-angle rays L that can leave the high-index cover glass 595_B'. High angle rays L within the QD layer 580_BThe recovery of (b) is a result of scattering within the QD layer. This therefore 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 LIMLs can help SPF 570 reflect high angle incident light. This additional LIML does not need to be pixilated and can be directly pasted onto the SPF 570.

Preferably, the interface between the LIML585 and the QD layer 580 should not introduce too much scattering. Preferably, to control the scattering of light at the interface between the LIML585 and the QD layer 580, the flatness at the interface between the LIML and the QD layer should be controlled so that the light energy scattered into rays with angles large enough to encounter TIR at the cover glass-air interface 597 is minimized. The volume scattering from the LIML585 and the surface scattering of the interface 587 between the LIML585 and the QD layer 580 are advantageously controlled such that light energy scattered to angles with sufficiently large angles to thereby encounter TIR at the cover glass-air interface 597 is minimized. The scattering of the film is characterized by haze (in transmission) while accounting for volume and surface scattering. The flatness of the interface 587 between the LIML585 and the QD layer 580 is controlled to limit the haze value, as measured according to ASTM D1003, to less than or equal to 50%, preferably less than or equal to 30%, and most preferably less than or equal to 5%.

The degree of improvement of LIML in the luminous efficiency of the QDCF depends on the reflectivity of LIML 585. Any material having a reflectivity lower than the refractive indices of the CF and QD layers 580 can be used as the LIML 585. The greater the difference in refractive index between the QD layer 580 and the LIML585, the better the performance of the LIML. This relationship of refractive indices means that the QD layer 580 can be fabricated with a reflectivity above 1.5 (the reflectivity of the cover glass 595), which will provide a larger range of possible refractive indices (window) for the LIML material. The cover glass 595 generally has a reflectivity of 1.5.

Calculations (results) show that the luminous efficiency of QDCF will gradually increase as the reflectance of LIML585 decreases from 1.5 to 1.0. This data is plotted in figure 8. When the reflectance of the 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 an embodiment, LIML having refractive index values in the range of 1.5 to 1.0 (inclusive) is desirable. According to some embodiments, the reflectivity of the 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 disclose some examples of nano-porous materials with low index and low scattering properties that can be used in LIML, "design rules for nanocomposite-based customizable materials", optical materials Express 8(11), 3456 (2018). The following table provides other examples of possible materials for LIML 585:

the black matrix between R, G and the B sub-pixel blocks light not associated with the display that would otherwise be present on the viewing side of the QDCF panel, thereby reducing the overall CR. In general, blocking of undesirable light by the black matrix is achieved by reflecting incident light by the black matrix material. Conventional black matrices include a reflective metal layer, such as chromium. Although most of the light reflected by the black matrix does not enter the final image, some of it is subject to scattering and reflection at several optical interfaces inside the LCD panel structure and eventually affects the final image, thereby reducing the contrast ratio, i.e., CR. Thus, in an exemplary QDCF panel structure, the black matrix is coated with a layer of light absorbing material (e.g., a polymer or oxide) to substantially reduce the unwanted reflection of the black matrix. In other examples, the black matrix is made of a photoresist resin in which melanin has been dispersed to reduce reflectance.

Referring to fig. 9, according to an embodiment of the present disclosure, the black matrix structure 600 is configured to have inclined sides and to be partially reflective, which also independently improves the light emission efficiency of the QDCF structure. Here, as mentioned above, the "partially reflective" feature simply 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 color filters in the color filter layer 590 and extends down through the QD layer 580, thereby defining sub-pixel regions R, G and B (see fig. 6). The black matrix 600 includes a side 602 inclined at an angle α, and thus the black matrix 600 has a substantially trapezoidal shape in a plan sectional view shown in fig. 9, and the black matrix 600 is narrower at the top than at the bottom near the cover glass 595. In addition, the side 602 facing the CF layer 590 and the QD layer 580 is reflective, while the remaining side of the top 603 facing the cover glass 595 is non-reflective. The side 602 is inclined at an angle α of 45 degrees with a deviation of 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 QDCF assemblies that use blue source light, the sloped sides 602 cause the red and green light generated in the QD layer 580 to be "directed" or "confined" to be re-directed toward the viewer. The blue source light may be reflected by the black matrix 600 towards the viewer and absorbed by the color filter (RG) or the black matrix.

According to some embodiments, a QDCF LCD device 500 is disclosed, comprising: a cover glass 595; a back reflector layer 510; a liquid crystal panel layer 550 between the cover glass and the back reflector layer; a backlight unit 520 (including a blue LED light source and a light guide plate) between the liquid crystal panel layer 550 and the back reflector 510, the backlight unit being configured to generate image forming light for the liquid crystal panel layer; a patterned quantum dot layer 580 between the cover glass and the liquid crystal panel layer; a color filter layer 590 between the cover glass and the quantum dot layer, the color filter 590 configured in combination with the quantum dot layer 580 to form a color by converting the wavelength of the image forming light from the backlight unit and passing through the liquid crystal panel 550; the bottom polarizer layer 540 is positioned between the liquid crystal panel layer 550 and the backlight unit 520; a top polarizer layer 560 is disposed between the liquid crystal panel layer and the quantum dot layer. In this embodiment of the QDCF LCD device, one of the following enhanced features is also incorporated: (a) LIML585 disposed between color filter layer 590 and quantum dot layer 580; (b) a backlight unit configured to generate collimated image forming light for 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 the top polarizer 560 are made of one or more compensation films comprising an a-plate, a C-plate, and a biaxial plate, respectively; (e) a privacy filter disposed between the top polarizer 560 and the quantum dot layer 580.

In other embodiments, QDCF LCD device 500 includes LIML585 between color filter layer 590 and quantum dot layer 580, and also incorporates one or more of the following enhanced characteristics: (a) one or both of the bottom polarizer 540 and the top polarizer 560 are made of E-type polarizer material; (b) a backlight unit configured to generate collimated image forming light for the liquid crystal panel layer; (c) the bottom polarizer 540 and the top polarizer 560 are made of compensation films including an a plate, a C plate, and a biaxial plate, respectively; (d) a privacy filter disposed between the top polarizer 560 and the quantum dot layer 580.

While embodiments of the present disclosure have been described, it is to be understood that the embodiments described are illustrative only, and that the scope of the invention is to be defined solely by the appended claims when given the full range of equivalency to which many variations and modifications thereof will become apparent to those skilled in the art from a perusal hereof.

Claims

1. A Quantum Dot Color Filter (QDCF) Liquid Crystal Display (LCD) device, comprising:

a cover glass;

a back 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 configured to generate 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 quantum dot layer in combination configured to form a color by converting a wavelength of the collimated image forming light;

a bottom polarizer layer between the liquid crystal panel layer and the backlight unit;

a top polarizer layer between the liquid crystal panel layer and the quantum dot layer; and is

Further comprising one or more of:

a low refractive index material layer (LIML) between the color filter layer and the quantum dot layer;

one or both of the bottom polarizer and the top polarizer comprises an E-type polarizer material;

the bottom polarizer and the top polarizer each comprise a compensation film comprising one or more of an A-plate, a C-plate, and a biaxial plate; and

a privacy filter between the top polarizer and the quantum dot layer.

2. The QDCF LCD device of claim 1, comprising: (a) and an ASTM D1003 haze value of an interface between the LIML and the quantum dot layer is less than or equal to 50%.

3. The QDCF LCD device of 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%.

4. The QDCF LCD device of 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%.

5. The QDCF LCD device of claim 1, comprising (a) and said refractive index values of said LIML being in the range of 1.5 to 1.0.

6. The QDCF LCD device of claim 5, wherein said LIML has a refractive index value in the range of 1.4 to 1.0.

7. The QDCF LCD device of claim 5, wherein said LIML has a refractive index value in the range of 1.3 to 1.0.

8. The QDCF LCD device of claim 5, wherein the index of refraction value of said LIML is in the range of 1.2 to 1.0.

9. The QDCF LCD device of claim 1, comprising (a); further comprising: a short pass filter between the quantum dot layer and the top polarizer; and an additional LIML between the quantum dot layer and the short-pass filter layer.

10. The QDCF LCD device of claim 1, comprising (e); further comprising a short pass filter between the quantum dot layer and the top polarizer; and the privacy filter is located between the top polarizer and the short-pass filter layer.

11. The QDCF LCD device of claim 1, wherein the collimated imaged light produced by the backlight unit has a half apex angle of less than or equal to ± 30 degrees.

12. The QDCF LCD device of claim 1, wherein the collimated imaging light produced by the backlight unit has a half apex angle of 20 degrees or less.

13. The QDCF LCD device of claim 1, wherein the collimated imaged light produced by the backlight unit has a half apex angle of less than or equal to ± 15 degrees.

14. The QDCF LCD device of claim 1, wherein the color filter layer and the quantum dot layer collectively comprise a plurality of pixel regions, each pixel region comprising a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region; and is

The device further includes a black matrix barrier structure extending through the color filter layer and the quantum dot layer, separating two adjacent sub-pixel regions, wherein the black matrix includes side surfaces in contact with the color filter layer and quantum dot layer;

wherein the side of the black matrix is inclined at an angle of 45 degrees, the inclination having a deviation of less than or equal to ± 20 degrees.

15. The QDCF LCD device of claim 14, wherein the side is tilted at a 45 degree angle with a deviation of less than or equal to ± 10 degrees.

16. The QDCF LCD device of claim 14, wherein the side is tilted at a 45 degree angle with a deviation of less than or equal to ± 5 degrees.

17. The QDCF LCD device of claim 14, wherein the side and bottom surfaces of the black matrix are reflective.

18. A Quantum Dot Color Filter (QDCF) Liquid Crystal Display (LCD) device, comprising:

a cover glass;

a back reflector layer;

a backlight unit between the liquid crystal panel layer and the back reflector, the backlight unit configured to generate 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 quantum dot layer in combination configured to form color by converting a wavelength of light from the backlight unit and formed by the collimated image of the liquid crystal panel;

a top polarizer layer between the liquid crystal panel layer and the quantum dot layer;

a low refractive index material layer (LIML) provided between the color filter layer and the quantum dot layer; and is

Further comprising one or more of:

19. The QDCF LCD device of 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%.

20. The QDCF LCD device of 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%.

21. The QDCF LCD device of 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%.

22. The QDCF LCD device of claim 18, wherein the LIML has a refractive index value in the range of 1.5 to 1.0.

23. The QDCF LCD device of claim 22, wherein the LIML has a refractive index value in the range of 1.4 to 1.0.

24. The QDCF LCD device of claim 22, wherein the LIML has a refractive index value in the range of 1.3 to 1.0.

25. The QDCF LCD device of claim 22, wherein the LIML has a refractive index value in the range of 1.2 to 1.0.

26. The QDCF LCD device of claim 18, further comprising a short pass filter between the quantum dot layer and the top polarizer; and is

Further included between the quantum dot layer and the short-pass filter layer is an additional LIML.

27. The QDCF LCD device of claim 18, comprising (d); further comprising a short pass filter between the quantum dot layer and the top polarizer; and the privacy filter is located between the top polarizer and the short-pass filter layer.

28. The QDCF LCD device of claim 18, wherein the collimated imaged light produced by the backlight unit has a half apex angle of less than or equal to ± 30 degrees.

29. The QDCF LCD device of claim 18, wherein the collimated imaged light produced by the backlight unit has a half apex angle of less than or equal to ± 20 degrees.

30. The QDCF LCD device of claim 18, wherein the collimated imaged light produced by the backlight unit has a half apex angle of less than or equal to ± 15 degrees.

31. The QDCF LCD device of claim 18, wherein the color filter layer and the quantum dot layer collectively comprise a plurality of pixel regions, each pixel region comprising a red sub-pixel region, a green sub-pixel region, and a blue sub-pixel region; and is

The device further includes a black matrix barrier structure extending through the color filter layer and the quantum dot layer, separating two adjacent sub-pixel regions, wherein the black matrix includes side surfaces in contact with the color filter layer and the quantum dot layer;

32. The QDCF LCD device of claim 31, wherein the side is tilted at a 45 degree angle with a deviation of less than or equal to ± 10 degrees.

33. The QDCF LCD device of claim 31, wherein the side is tilted at a 45 degree angle with a deviation of less than or equal to ± 5 degrees.

34. The QDCF LCD device of claim 31, wherein the side and bottom surfaces of the black matrix are reflective.