Backlight and display system

Abstract

A backlight includes an extended illumination source, one or more light converting films, and first and second prismatic films. The extended illumination source includes an extended emission surface and is configured to emit a blue light through the extended emission surface toward a display panel. The one or more light converting films are disposed on the extended emission surface and are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights. The first prismatic film is disposed between the one or more light converting films and the extended emission surface and the second prismatic film is disposed between the first prismatic film and the extended emission surface.

Description

BACKLIGHT AND DISPLAY SYSTEMTechnical Field

[0001] The present disclosure relates to a backlight and a display system.Background

[0002] Typically, advancements in conventional display systems strive to achieve a superior viewing experience for a viewer by improving an image quality. One aspect of this endeavor involves management of an emitted light from a backlight in the conventional display system to achieve a superior contrast and brightness. However, the conventional display system faces some challenges to achieve a bright and a uniform light distribution across a display panel while having a simple structural design.

[0003] Therefore, the industry demands a display system with a backlight that may maintain, or even enhance, the brightness and the uniformity of the emitted light that may improve the viewing experience for the viewer, while having a simplified overall design and construction.Summary

[0004] In a first aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit a blue light through the extended emission surface toward the display panel. The emitted blue light includes an emitted blue spectrum including an emitted blue full width at half maximum (FWHM). The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source. The one or more light converting films include at least green and red emission spectra having corresponding non-overlapping green and red FWHMs. The one or more light converting films are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs. The backlight further includes a first prismatic film disposed between the one or more light converting films and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend toward or away from the extended illumination source. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously alongsubstantially a same second longitudinal direction different from the first longitudinal direction and extend toward or away from the extended illumination source.

[0005] In a second aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit a blue light through the extended emission surface toward the display panel. The emitted blue light includes an emitted blue spectrum including an emitted blue FWHM. Further, the emitted blue FWHM is disposed in a blue wavelength range extending from about 420 nanometers (nm) to about 480 nm. The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source. The one or more light converting films include one or more of phosphor, fluorescent dye, and quantum dots. The one or more light converting films are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and red emission spectra. The green and red emission spectra include corresponding non-overlapping green and red FWHMs. The at least green and red lights have respective green and red wavelengths disposed in the respective green and red FWHMs. The green FWHM is disposed in a green wavelength range extending from about 490 nm to about 560 nm and the red FWHM is disposed in a red wavelength range extending from about 590 nm to about 680 nm. The backlight further includes a first prismatic film disposed between the one or more light converting films and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend toward or away from the extended illumination source. Each of the first prisms has two first sides extending along the first longitudinal direction and extending from the first substrate and meeting at a first tip defining a first apex angle therebetween. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extend toward or away from the extended illumination source.Each of the second prisms has two second sides extending along the second longitudinal direction and extending from the second substrate and meeting at a second tip defining a second apex angle therebetween. Furthermore, a magnitude of difference between the first apex angle and the second apex angle is greater than about 5 degrees.

[0006] In a third aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit a blue light through the extended emission surfacetoward the display panel. The emitted blue light includes an emitted blue spectrum including an emitted blue FWHM. The emitted blue FWHM is disposed in a blue wavelength range extending from about 420 nm to about 480 nm. The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source. The one or more light converting films include one or more of phosphor, fluorescent dye, and quantum dots. The one or more light converting films are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and red emission spectra. The green and red emission spectra include corresponding non-overlapping green and red FWHMs. The at least green and red lights have respective green and red wavelengths disposed in the respective green and red FWHMs. The green FWHM is disposed in a green wavelength range extending from about 490 nm to about 560 nm and the red FWHM is disposed in a red wavelength range extending from about 590 nm to about 680 nm. The backlight further includes a first prismatic film disposed between the one or more light converting films and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend toward or away from the extended illumination source. Each of the first prisms has two first sides extending along the first longitudinal direction and extending from the first substrate and meeting at a first tip defining a first apex angle therebetween. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extend toward or away from the extended illumination source. Each of the second prisms has two second sides extending along the second longitudinal direction and extending from the second substrate and meeting at a second tip defining a second apex angle therebetween. Furthermore, the first apex angle is less than the second apex angle.

[0007] In a fourth aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit a blue light through the extended emission surface toward the display panel. The emitted blue light includes an emitted blue spectrum including an emitted blue FWHM. The emitted blue FWHM is disposed in a blue wavelength range extending from about 420 nm to about 480 nm. The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source. The one or more light converting films include one or more of phosphor, fluorescent dye, and quantum dots. The one or more light converting films are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at leastgreen and red lights having respective green and red emission spectra. The green and red emission spectra include corresponding non-overlapping green and red FWHMs. The at least green and red lights have respective green and red wavelengths disposed in the respective green and red FWHMs. The green FWHM is disposed in a green wavelength range extending from about 490 nm to about 560 nm and the red FWHM is disposed in a red wavelength range extending from about 590 nm to about 680 nm. The backlight further includes a first prismatic film disposed between the one or more light converting films and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend toward or away from the extended illumination source. Each of the first prisms has two first sides extending along the first longitudinal direction and extending from the first substrate and meeting at a first tip defining a first apex angle therebetween. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extend toward or away from the extended illumination source. Each of the second prisms has two second sides extending along the second longitudinal direction and extending from the second substrate and meeting at a second tip defining a second apex angle therebetween. Furthermore, the first apex angle and the second apex angle are substantially equal. When each of the first and second apex angles increases from about 50 degrees to an optimal angle between about 70 degrees and about 80 degrees, a brightness uniformity of the image as perceived by the viewer increases. Furthermore, when each of the first and second apex angles increases from the optimal angle to about 110 degrees, the brightness uniformity of the image decreases.

[0008] In a fifth aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit light through the extended emission surface toward the display panel. The backlight further includes an optical diffuser disposed on the extended illumination source. The optical diffuser has a diffuse optical transmittance of greater than about 10% for at least one wavelength of the emitted light. The backlight further includes a first prismatic film disposed between the optical diffuser and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend away from the extended illumination source toward the viewer. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously along substantially a same second longitudinaldirection different from the first longitudinal direction and extend toward the extended illumination source away from the viewer. The backlight further includes a third prismatic film disposed on the optical diffuser opposite the first prismatic film. The third prismatic film includes a plurality of third prisms extending along substantially a same third longitudinal direction. Furthermore, the backlight includes a fourth prismatic film disposed on the third prismatic film opposite the optical diffuser. The fourth prismatic film includes a plurality of fourth prisms extending along substantially a same fourth longitudinal direction different from the third longitudinal direction.

[0009] In a sixth aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit a blue light through the extended emission surface toward the display panel. The emitted blue light includes an emitted blue spectrum including a blue emitted FWHM. The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source. The one or more light converting films include at least green and red emission spectra including corresponding non-overlapping green and red FWHMs. The one or more light converting films are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs. The backlight further includes a first prismatic film disposed between the one or more light converting films and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend toward or away from the extended illumination source. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extend toward or away from the extended illumination source. Furthermore, the backlight does not include any other prismatic film except the first and second prismatic films between the one or more light converting films and the extended illumination source.

[0010] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.Brief Description of the Drawings

[0011] Exemplary embodiments disclosed herein may be more completely understood in consideration of the following detailed description in connection with the following figures. Thefigures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

[0012] FIG. 1 A shows a schematic view of a display system, according to an embodiment of the present disclosure;

[0013] FIG. IB shows a schematic view of the display system, according to another embodiment of the present disclosure;

[0014] FIG. 2 shows a detailed sectional view of a first prismatic film and a second prismatic film, according to an embodiment of the present disclosure;

[0015] FIG. 3 shows a detailed schematic sectional view of a reflective polarizer, according to an embodiment of the present disclosure;

[0016] FIG. 4 shows a graph depicting a relative brightness versus a brightness uniformity for the display system including identical first and second prismatic films, according to an embodiment of the present disclosure;

[0017] FIG. 5 shows a graph depicting the relative brightness versus the brightness uniformity for the display system including different first and second prismatic films, according to an embodiment of the present disclosure;

[0018] FIG. 6A shows a graph depicting the relative brightness versus the brightness uniformity for the display system including identical first and second prismatic films when first prisms of the first prismatic film extend towards the viewer and away from the viewer, according to an embodiment of the present disclosure;

[0019] FIG. 6B shows a graph depicting the relative brightness versus the brightness uniformity for the display system including different first and second prismatic films when first prisms of the first prismatic film extend towards the viewer and away from the viewer, according to an embodiment of the present disclosure;

[0020] FIG. 7 A shows a graph depicting an axial brightness efficiency versus the brightness uniformity for the display system including identical first and second prismatic films having different tip radius, according to an embodiment of the present disclosure;

[0021] FIG. 7B shows a graph depicting an axial brightness efficiency versus the brightness uniformity for the display system including identical first and second prismatic films having different valley radius, according to an embodiment of the present disclosure;

[0022] FIG. 8A shows a graph depicting the axial brightness efficiency versus the brightness uniformity versus the tip radius of the first and second prismatic films when respective first and second apex angles are of about 60 degrees, according to an embodiment of the present disclosure;

[0023] FIG. 8B shows a graph depicting the axial brightness efficiency versus the brightness uniformity versus the valley radius of the first and second prismatic films when the respective firstand second apex angles are of about 60 degrees, according to an embodiment of the present disclosure;

[0024] FIG. 9A shows a graph depicting the axial brightness efficiency versus the brightness uniformity versus the tip radius of the first and second prismatic films when respective first and second apex angles are of about 74 degrees, according to an embodiment of the present disclosure;

[0025] FIG. 9B shows a graph depicting the axial brightness efficiency versus the brightness uniformity versus the valley radius of the first and second prismatic films when the respective first and second apex angles are of about 74 degrees, according to an embodiment of the present disclosure;

[0026] FIG. 10A shows a graph depicting the axial brightness efficiency versus the brightness uniformity versus the tip radius of the first and second prismatic films when respective first and second apex angles are of about 80 degrees, according to an embodiment of the present disclosure; and

[0027] FIG. 10B shows a graph depicting the axial brightness efficiency versus the brightness uniformity versus the valley radius of the first and second prismatic films when the respective first and second apex angles are of about 80 degrees, according to an embodiment of the present disclosure.Detailed Description

[0028] In the following description, reference is made to the accompanying figures that form a part thereof and in which various embodiments are shown by way of illustration. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0029] In the following disclosure, the following definitions are adopted.

[0030] As used herein, all numbers should be considered modified by the term “about”. As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably.

[0031] As used herein as a modifier to a property or attribute, the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties).

[0032] The term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0033] The term “about”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 5% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0034] As used herein, the terms “first” and “second” are used as identifiers. Therefore, such terms should not be construed as limiting of this disclosure. The terms “first” and “second” when used in conjunction with a feature or an element can be interchanged throughout the embodiments of this disclosure.

[0035] As used herein, “at least one of A and B” should be understood to mean “only A, only B, or both A and B”.

[0036] As used herein, the term “layer” generally refers to a thickness of material within a film that has a relatively consistent chemical composition. Layers may be of any type of material including polymeric, cellulosic, metallic, or a blend thereof. A given polymeric layer may include a single polymer-type or a blend of polymers and may be accompanied by additives. A given layer may be combined or connected to other layers to form films. A layer may be either partially or fully continuous as compared to adjacent layers or the film. A given layer may be partially or fully coextensive with adjacent layers. A layer may contain sub-layers.

[0037] Typically, advancements in conventional display systems strive to achieve a superior viewing experience for a viewer by improving an image quality. One aspect of this endeavor involves management of an emitted light from a backlight in the conventional display system to achieve a superior contrast and brightness. However, the conventional display system faces some challenges to achieve a bright and a uniform light distribution across a display panel while having a simple structural design. In some cases, the conventional display system may use a low-resolution lightemitting diode (LED) backlight to modulate overall light level in zones of the display panel that are smaller than a full display region of the display panel, but larger than a pixel size. This may a lead to a variable a brightness which may negatively affect the viewing experience for the viewer.

[0038] Therefore, the industry demands a display system with a backlight that may maintain, or even enhance, a brightness efficiency and a brightness uniformity of the emitted light that may improve the viewing experience for the viewer, while having a simplified overall design and construction.

[0039] The present disclosure relates to a backlight for providing illumination to a display panel configured to display an image to a viewer. The backlight includes an extended illumination source including one or more light sources and an extended emission surface. The extended illumination source is configured to emit a blue light through the extended emission surface toward the display panel. The emitted blue light includes an emitted blue spectrum including an emitted blue full width at half maximum (FWHM). The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source. The one or more light converting films include at least green and red emission spectra having corresponding nonoverlapping green and red FWHMs. The one or more light converting films are configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and redwavelengths disposed in the respective green and red FWHMs. The backlight further includes a first prismatic film disposed between the one or more light converting films and the extended emission surface. The first prismatic film includes a first substrate and a plurality of first prisms disposed on the first substrate. The first prisms extend continuously along substantially a same first longitudinal direction and extend toward or away from the extended illumination source. The backlight further includes a second prismatic film disposed between the first prismatic film and the extended emission surface. The second prismatic film includes a second substrate and a plurality of second prisms disposed on the second substrate. The second prisms extend continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extend toward or away from the extended illumination source.

[0040] The first and second prismatic films disposed between the one or more light converting films and the extended emission surface may evenly distribute the emitted light across the one or more light converting films. This may enhance brightness efficiency and brightness uniformity of the illumination that reaches the display panel. Therefore, individual zones of the display panel may not be visible, improving viewing experience for the viewer.

[0041] Furthermore, the backlight including the first and second prismatic films of the present disclosure may be easier to fabricate compared to conventional solutions. In addition, the backlight may enhance the brightness efficiency and the brightness uniformity without requiring any modification to an extended illumination source or registration of an LED array.

[0042] Referring now to figures, FIG. 1 A shows a schematic view of a display system 300, according to an embodiment of the present disclosure. In some cases, the display system 300 may be implemented in screens of smart devices such as smartphones, notebooks, tablets, etc.

[0043] The display system 300 defines mutually orthogonal x, y, and z-axes. The x and y-axes are in-plane axes of the display system 300, while the z-axis is a transverse axis disposed along a thickness of the display system 300. In other words, the x and y-axes are disposed along a plane of the display system 300, while the z-axis is perpendicular to the plane of the display system 300.

[0044] In the illustrated embodiment of FIG. 1 A, the display system 300 includes a backlight 200. The backlight 200 is configured to provide an illumination 41 to a display panel 40 configured to display an image 42 to a viewer (not shown). In some embodiments, the display panel 40 includes a liquid crystal display panel. Further, in some embodiments, the display panel 40 is an organic light emitting display (OLED).

[0045] The backlight 200 includes an extended illumination source 21 including one or more light sources 20 and an extended emission surface 22. The extended illumination source 21 is configured to emit a blue light 23 through the extended emission surface 22 toward the display panel 40. In some embodiments, the display system 300 includes the display panel 40 disposed on the backlight 200 and configured to receive the blue light 23 emitted through the extended emissionsurface 22 and display the image 42. The emitted blue light 23 includes an emitted blue spectrum including an emitted blue full width at half maximum (FWHM).

[0046] In the illustrated example of FIG. 1 A, the backlight 200 further includes one or more light converting films 15 disposed on the extended emission surface 22 of the extended illumination source 21. In some embodiments, the one or more light converting films 15 include one or more of phosphor, fluorescent dye, and quantum dots. The one or more light converting films 15 include at least green and red emission spectra including corresponding non-overlapping green and red FWHMs. The one or more light converting films 15 are configured to receive the emitted blue light 23 through the extended emission surface 22 and convert at least portions of the received emitted blue light 23 to at least green and red lights 15g, 15r having respective green and red wavelengths disposed in the respective green and red FWHMs.

[0047] In some embodiments, the emitted blue FWHM is disposed in a blue wavelength range extending from about 420 nanometers (nm) to about 480 nm. In some embodiments, the green FWHM is disposed in a green wavelength range extending from about 490 nm to about 560 nm. In some embodiments, the red FWHM is disposed in a red wavelength range extending from about 590 nm to about 680 nm.

[0048] The backlight 200 further includes a first prismatic film 50 disposed between the one or more light converting films 15 and the extended emission surface 22. The first prismatic film 50 includes a first substrate 51 and a plurality of first prisms 52 disposed on the first substrate 51.

[0049] The first prisms 52 extend continuously along substantially a same first longitudinal direction. In some embodiments, the first longitudinal direction is substantially along the x-axis. Further, the first prisms 52 extend toward or away from the extended illumination source 21. In some embodiments, the first prisms 52 extend away from the extended illumination source 21 towards the viewer.

[0050] The backlight 200 further includes a second prismatic film 60 disposed between the first prismatic film 50 and the extended emission surface 22. The second prismatic film 60 includes a second substrate 61 and a plurality of second prisms 62 disposed on the second substrate 61.

[0051] The second prisms 62 extend continuously along substantially a same second longitudinal direction different from the first longitudinal direction. In some embodiments, the first and second longitudinal directions are substantially orthogonal to each other. In some embodiments, the second longitudinal direction is substantially along the y-axis. Further, the second prisms 62 extend toward or away from the extended illumination source 21. In some embodiments, the second prisms 62 extend toward the extended illumination source 21 away from the viewer.

[0052] In some embodiments, each of the first prisms 52 has two first sides 58 extending along the first longitudinal direction. The two first sides 58 extend from the first substrate 51 and meet at a first tip 55 defining a first apex angle 56 therebetween. Similarly, in some embodiments, each of the second prisms 62 has two second sides 68 extending along the second longitudinal direction. The twosecond sides 68 extend from the second substrate 61 and meet at a second tip 65 defining a second apex angle 66 therebetween. As shown in FIG. 1A, the first substrate 51 has a first average thickness 54. Similarly, the second substrate 61 has a second average thickness 64. In some embodiments, the first and second substrates 51, 61 may have a textured surface opposite to the first and second prisms 52, 62.

[0053] In some embodiments, the first and second prisms 52, 62 include respective first and second refractive indices. Each of the first and second refractive indices is in a range from about 1.48 to about 1.65. Further, in some embodiments, the first and second refractive indices are substantially equal. Furthermore, in some embodiments, the first refractive index is less than the second refractive index.

[0054] In the illustrated embodiment of FIG. 1 A, the backlight 200 further includes a third prismatic film 70 disposed on the one or more light converting films 15 opposite the first and second prismatic films 50, 60. The third prismatic film 70 includes a plurality of third prisms 72 extending along substantially a same third longitudinal direction. In some embodiments, the third longitudinal direction is substantially along the y-axis.

[0055] In the illustrated embodiment of FIG. 1 A, the backlight 200 further includes a fourth prismatic film 80 disposed on the third prismatic film 70 opposite the one or more light converting films 15. The fourth prismatic film 80 includes a plurality of fourth prisms 82 extending along substantially a same fourth longitudinal direction different from the third longitudinal direction. In some embodiments, the fourth longitudinal direction is substantially along x-axis. In some embodiments, the third and fourth longitudinal directions are substantially orthogonal to each other.

[0056] In some embodiments, the backlight 200 does not include any other prismatic film except the first and second prismatic films 50, 60 between the one or more light converting films 15 and the extended illumination source 21.

[0057] In some embodiments, the backlight 200 further includes a reflective polarizer 100 disposed on the one or more light converting films 15 opposite the first and second prismatic films 50, 60.

[0058] In some embodiments, the extended illumination source 21 includes a back reflector 27 substantially co-extensive in length and width with, and spaced apart from, the extended emission surface 22. The back reflector 27 may include a reflecting surface (e.g., a metallic surface) or may have a multi-layer configuration. In some embodiments, the extended emission surface 22 and the back reflector 27 define an optical cavity 28 therebetween. Furthermore, in some embodiments, the one or more light sources 20 are disposed in the optical cavity 28.

[0059] FIG. IB shows a schematic view of the display system 300, according to another embodiment of the present disclosure.

[0060] In the illustrated example of FIG. IB, the display system 300 includes a backlight 205. The backlight 205 shown in FIG. IB is substantially similar to the backlight 200 shown in FIG. 1A,with like elements designated by like reference characters. However, the backlight 205 does not include the one or more light converting films 15 as shown in the backlight 200 of FIG. 1A.

[0061] In the illustrated embodiment of FIG. IB, the extended illumination source 21 is configured to emit the light 150b, 150g, 150r instead of the emitted blue light 23 (shown in FIG. 1A) through the extended emission surface 22 toward the display panel 40.

[0062] In some embodiments, the one or more light sources 20 include a plurality of micro-light- emitting diodes (LEDs) 150 configured to emit light. In some embodiments, at least one of the microLEDs is configured to emit a blue light 150b, a green light 150g, and a red light 150r. In some embodiments, the micro-LEDs 150 are organic micro-LEDs.

[0063] In some embodiments, at least one of the micro-LEDs 150 (i.e., a blue micro-LED 10b) is configured to emit the blue light 150b having the blue wavelength in the blue wavelength range. In some embodiments, at least one of the micro-LEDs (i.e., a green micro-LED 10g) is configured to emit the green light 150g having the green wavelength in the green wavelength range. In some embodiments, at least one of the micro-LEDs (i.e., a red micro-LED lOr) is configured to emit the red light 150r having the red wavelength in the red wavelength range.

[0064] Furthermore, in the illustrated embodiment of FIG. IB, the backlight 205 includes an optical diffuser 90 disposed on the extended illumination source 21. The optical diffuser 90 includes a diffuse optical transmittance of greater than about 10% for at least one wavelength of the emitted light i.e., the blue light 150b, the green light 150g, and / or the red light 150r.

[0065] The backlight 205 further includes the first prismatic film 50 disposed between the optical diffuser 90 and the extended emission surface 22. The backlight 205 further includes the second prismatic film 60 disposed between the first prismatic film 50 and the extended emission surface 22. Furthermore, the backlight 205 includes the third prismatic film 70 disposed on the optical diffuser 90 opposite the first prismatic film 50 and the fourth prismatic film 80 disposed on the third prismatic film 70 opposite the optical diffuser 90.

[0066] In some embodiments, the backlight 205 does not include any other prismatic film except the first and second prismatic films 50, 60 between the optical diffuser 90 and the extended illumination source 21.

[0067] FIG. 2 shows a detailed sectional view of the first prismatic film 50 and the second prismatic film 60, according to an embodiment of the present disclosure.

[0068] As is discussed above, the first prismatic film 50 includes the first substrate 51 and the plurality of first prisms 52 disposed on the first substrate 51. Further, each of the first prisms 52 has the two first sides 58 extending along the first longitudinal direction. The first two sides and extend from the first substrate 51 and meet at the first tip 55 defining the first apex angle 56 therebetween.

[0069] Similarly, the second prismatic film 60 includes the second substrate 61 and the plurality of second prisms 62 disposed on the second substrate 61. Further, each of the second prisms 62 has the two second sides 68 extending along the second longitudinal direction. The two second sides 68extend from the second substrate 61 and meet at the second tip 65 defining the second apex angle 66 therebetween.

[0070] In some embodiments, each of the first and second apex angles 56, 66 is greater than about 50 degrees and less than about 110 degrees. In some embodiments, each of the first and second apex angles 56, 66 is greater than about 60 degrees and less than about 90 degrees. In some embodiments, the first and second apex angles 56, 66 are substantially equal. In some embodiments, the first apex angle 56 is less than the second apex angle 66. In some embodiments, a magnitude of difference between the first apex angle 56 and the second apex angle 66 is greater than about 5 degrees. In some embodiments, the magnitude of difference between the first apex angle 56 and the second apex angle 66 is greater than about 10 degrees.

[0071] In some embodiments, the first and second tips 55, 65 are substantially round and have a tip radius TR of less than about 7 microns. In some embodiments, the first and second tips 55, 65 have the tip radius TR of less than about 6 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron.

[0072] In some embodiments, two adjacent first prisms 52 meet at a first valley 53 and two adjacent second prisms 62 meet at a second valley 63. In some embodiments, the first and second valleys 53, 63 are substantially round and have a valley radius VR of less than about 7 microns. In some embodiments, the first and second valleys 53, 63 have the valley radius VR of less than about 6 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron.

[0073] In some embodiments, the first and second substrates 51, 61 have the respective first and second average thicknesses 54, 64 of greater than about 50 microns and less than about 400 microns. In some embodiments, the first and second substrates 51, 61 have the respective first and second average thicknesses 54, 64 of greater than about 100 microns and less than about 400 microns. In some embodiments, the first average thickness 54 and the second average thickness 64 are substantially equal. In some embodiments, the first average thickness 54 is less than the second average thickness 64.

[0074] FIG. 3 shows a detailed schematic sectional view of the reflective polarizer 100, according to an embodiment of the present disclosure.

[0075] In some embodiments, the reflective polarizer 100 includes a plurality of polymeric microlayers 43 numbering at least 10 in total. In some embodiments, each of the polymeric microlayers 43 has an average thickness t of less than about 500 nm. The term “average thickness t”, as used herein, refers to an average of thicknesses measured at multiple points across a plane (i.e., the x-y plane) of each of the plurality of polymeric microlayers 43. Furthermore, in some embodiments, the thickness direction extends substantially along the z-axis.

[0076] For a substantially normally incident light 35 and for at least one visible wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the plurality of polymeric microlayers 43 reflects more than about 60% of the incident light 35 having an in-plane firstpolarization state and transmits more than about 60% of the incident light 35 having an in-plane orthogonal second polarization state. In some embodiments, the first polarization state extends along the x-axis and the second polarization state extends along the y-axis. In some embodiments, the first polarization state may correspond to a p-polarization state, while the second polarization state may correspond to a s-polarization state.

[0077] In some embodiments, the reflective polarizer 100 further includes at least one skin layer 33 including an average thickness st of greater than about 500 nm. The term “average thickness st”, as used herein, refers to an average of thicknesses measured at multiple points across a plane (i.e., the x-y plane) of each of the at least one skin layer 33. Furthermore, in some embodiments, the thickness direction extends substantially along the z-axis.

[0078] FIG. 4 shows a graph 400 depicting a relative brightness versus a brightness uniformity for the display system 300 (shown in FIGS. 1A, and IB) including identical first and second prismatic films 50, 60 (shown in FIGS. 1 A, and IB), according to an embodiment of the present disclosure.

[0079] The brightness uniformity is expressed in the abscissa. The relative brightness is expressed in percentage (%) in the ordinate.

[0080] For the purposes of this specification, “the brightness uniformity” or simply “uniformity” shall be defined as a maximum luminance value divided by a minimum luminance value as measured across the display panel 40 (shown in FIGS. 1 A, and IB) or a portion of the display panel 40 being measured. That is, the term “uniformity”, only has meaning when compared relative to a second measured uniformity value. For example, a larger value for the uniformity as calculated in this fashion is less desirable than a smaller value. That is, a larger uniformity value represents an increase in “luminance mura”, or uneven spots on the display panel 40.

[0081] Referring to FIGS. 1 A-4, the graph 400 includes a curve 402 depicting the relative brightness versus brightness uniformity for the display system 300 including the identical first and second prismatic films 50, 60 including the respective first and second substrates 51, 61 having the respective first and second average thicknesses 54, 64 equal to about 10 mil.

[0082] The curve 402 includes a point 402A depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 90 degrees. The curve 402 further includes a point 402B depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 80 degrees. The curve 402 further includes a point 402C depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 74 degrees. The curve 402 further includes a point 402D depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 70 degrees. Furthermore, the curve 402includes a point 402E depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 60 degrees.

[0083] The graph 400 includes a curve 404 depicting the relative brightness versus brightness uniformity for the display system 300 including the identical first and second prismatic films 50, 60 including the respective first and second substrates 51, 61 having the respective first and second average thicknesses 54, 64 equal to about 9 mil.

[0084] The curve 404 includes a point 404A depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 90 degrees. The curve 404 further includes a point 404B depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 80 degrees. The curve 404 further includes a point 404C depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 74 degrees. The curve 404 further includes a point 404D depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 70 degrees. Furthermore, the curve 404 includes a point 404E depicting the relative brightness versus brightness uniformity when the identical first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 60 degrees.

[0085] The graph 400 further includes a point 406 depicting the relative brightness versus brightness uniformity for the display system 300 including the identical first and second prismatic films 50, 60 having the respective first and second average thicknesses 54, 64 equal to about 6 mil and the respective first and second apex angles 56, 66 of about 70 degrees.

[0086] The graph 400 further includes a point 408 depicting the relative brightness versus brightness uniformity for the display system 300 including the identical first and second prismatic films 50, 60 having the respective first and second average thicknesses 54, 64 equal to about 4 mil and the respective first and second apex angles 56, 66 of about 70 degrees.

[0087] The graph 400 further includes a point 410 depicting the relative brightness versus brightness uniformity of a comparative display system including 3 Keiwa waffle films having a total thickness of about 540 micrometers (um) instead of the first and second prismatic films 50, 60.

[0088] The graph 400 further includes a point 412 depicting the relative brightness versus brightness uniformity of the comparative display system including 3 Keiwa waffle films having a total thickness of about 330 um instead of the first and second prismatic films 50, 60.

[0089] The 3 Keiwa waffle films having the total thickness of 540 um may be used in devices, such as, notebooks, while the 3 Keiwa waffle films having the total thickness of 330 um may be used in devices such as, tablets.

[0090] The 3 Keiwa waffle films having the total thickness of 540 um and 3 Keiwa waffle films having the total thickness of 330 um have different substrate thicknesses while a waffle structure geometry of the 3 Keiwa waffle films remains the same.

[0091] Each Keiwa waffle film of the 3 Keiwa waffle films is made out of polycarbonate with an inverted pyramid structure, i.e., air forms a pyramid shape. Each pyramid of the inverted pyramid structure has a height of about 50 um, a pitch of about 100 um, an apex angle of about 90 degrees, a ridge rounding radius of about 12 um, and a tip rounding radius of about 0.5 um. Further, the inverted pyramid structure of each Keiwa waffle film of the 3 Keiwa waffle films extends toward an illumination source of the comparative display system.

[0092] The relative brightness and the brightness uniformity corresponding to the points 410, 412 are used as baseline for comparison of the relative brightness and the brightness uniformity of the display system 300 including the first and second prismatic films 50, 60.

[0093] Still referring to FIGS. 1A-4, as is apparent from the curves 402, 404, in some embodiments, when each of the first and second apex angles 56, 66 increases, the brightness of the image 42 as perceived by the viewer decreases. In some embodiments, when each of the first and second apex angles 56, 66 increases from about 50 degrees to about 110 degrees, the brightness of the image 42 as perceived by the viewer decreases. Specifically, as shown in the graph 400, in some embodiments, when each of the first and second apex angles 56, 66 increases from about 60 degrees to about 90 degrees, the brightness of the image 42 as perceived by the viewer decreases.

[0094] Further, as is apparent from the curves 402, 404, in some embodiments, when each of the first and second apex angles 56, 66 increases to an optimal angle OA, the brightness uniformity of the image 42 as perceived by the viewer increases, and when each of the first and second apex angles 56, 66 increases from the optimal angle OA, the brightness uniformity of the image 42 decreases.

[0095] In some embodiments, when each of the first and second apex angles 56, 66 increases from about 50 degrees to the optimal angle OA between about 70 degrees and about 80 degrees, the brightness uniformity of the image 42 as perceived by the viewer increases, and when each of the first and second apex angles 56, 66 increases from the optimal angle OA to about 110 degrees, the brightness uniformity of the image 42 decreases. Specifically, as shown in the graph 400, in some embodiments, when each of the first and second apex angles 56, 66 increases from about 60 degrees to the optimal angle OA of about 74 degrees, the brightness uniformity of the image 42 as perceived by the viewer increases, and when each of the first and second apex angles 56, 66 increases from the optimal angle OA to about 90 degrees, the brightness uniformity of the image 42 decreases.

[0096] Therefore, for the first and second prismatic films 50, 60 having equal respective first and second apex angles 56, 66, there may be a tradeoff curve between the relative brightness and the brightness uniformity. Further, for a given equal first and second average thicknesses 54, 64 there is an optimal angle, i.e., the optimal angle OA.

[0097] In addition, as is apparent from the curves 402, 404 and the points 406, 408, a greater substrate thickness (i.e., the first and second average thicknesses 54, 64) may help to achieve better brightness uniformity as there is a larger gap along the z-axis for the light (e.g., the emitted blue light 23) to spread.

[0098] FIG. 5 shows a graph 500 depicting the relative brightness versus the brightness uniformity for the display system 300 (shown in FIGS. 1A, and IB) including different first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The graph 500 includes the curve 402, and the points 410, 412 of FIG. 4 for comparison purposes.

[0099] Referring to FIGS. 1 A-5, the graph 500 includes a point 502 depicting the relative brightness versus brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 75 degrees, a substrate thickness ratio of about 0.5, and the respective first and second refractive indices of about 1.56. The substrate thickness ratio may be defined as a ratio of the second average thickness 64 and a sum of the first and second average thicknesses 54, 64. In some embodiments, the sum of the first and second average thicknesses 54, 64 may be equal to about 20 mils.

[0100] The graph 500 further includes a point 504 depicting the relative brightness versus brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 65 degrees and 75 degrees, the substrate thickness ratio of about 0.7, and the respective first and second refractive indices of about 1.52 and 1.56.

[0101] The graph 500 further includes a point 506 depicting the relative brightness versus brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 65 degrees and 80 degrees, the substrate thickness ratio of about 0.7, and the respective first and second refractive indices of about 1.52.

[0102] The graph 500 further includes a point 508 depicting the relative brightness versus brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 60 degrees and 85 degrees, the substrate thickness ratio of about 0.7, and the respective first and second refractive indices of about 1.52.

[0103] The graph 500 further includes a point 510 depicting the relative brightness versus brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 60 degrees and 80 degrees, the substrate thickness ratio of about 0.7, and the respective first and second refractive indices of about 1.48 and 1.52. As is apparent from the graph 500, this arrangement of the first and second prismaticfilms 50, 60 may substantially improve the brightness while providing acceptable brightness uniformity.

[0104] Further, as is apparent from the graph 500, allowing different configurations (e.g., different first and second apex angles 56, 66) for the first and second prismatic films 50, 60 may further improve the relative brightness and the brightness uniformity of the display system 300. Further, the display system 300 may have brightness improvement at similar brightness uniformity of greater than about 10% as compared to the comparative display system including 3 Keiwa waffle films.

[0105] FIG. 6A shows a graph 600 depicting the relative brightness versus the brightness uniformity for the display system 300 (shown in FIGS. 1A, and IB) including identical first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure.

[0106] Referring to FIGS. 1A-1B and 6 A, the graph 600 includes a cluster of points 600U. The cluster of points 600U is depicted by a plurality of triangles pointing in an upward direction. The upward direction of the triangles depicts that the first prisms 52 of the first prismatic film 50 extend away from the extended illumination source 21 towards the viewer.

[0107] The graph 600 further includes a cluster of points 600D. The cluster of points 600D is depicted by a plurality of triangles pointing in a downward direction. The downward direction of the triangles depicts that the first prisms 52 of the first prismatic film 50 extend toward the extended illumination source 21 away from the viewer.

[0108] In both of the clusters of points 600U, 600D of the graph 600, the second prisms 62 of the second prismatic film 60 extend toward the extended illumination source 21 away from the viewer. Further, the first and second apex angles 56, 66 corresponding to each point of the clusters of points 600U, 600D of the graph 600 are equal. Values of the first and second apex angles 56, 66 of some of the points are shown in brackets.

[0109] FIG. 6B shows a graph 602 depicting the relative brightness versus the brightness uniformity for the display system 300 (shown in FIGS. 1A, and IB) including different first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure.

[0110] Referring to FIGS. 1A-1B and 6B, the graph 602 includes a cluster of points 602U. The cluster of points 602U is depicted by a plurality of triangles pointing in an upward direction. The upward direction of the triangles depicts that the first prisms 52 of the first prismatic film 50 extend away from the extended illumination source 21 towards the viewer.

[0111] The graph 602 further includes a cluster of points 602D. The cluster of points 602D is depicted by a plurality of triangles pointing in a downward direction. The downward direction of the triangles depicts that the first prisms 52 of the first prismatic film 50 extend toward the extended illumination source 21 away from the viewer.

[0112] In both of the clusters of points 602U, 602D of the graph 602, the second prisms 62 of the second prismatic film 60 extend toward the extended illumination source 21 away from the viewer. Further, the first and second apex angles 56, 66 corresponding to each point in the clusters of points 602U, 602D of the graph 602 are not equal. Values of the first and second apex angles 56, 66 of some of the points are shown in brackets. The first value in each of the brackets is the second apex angle 66 and the second value in each of the brackets is the first apex angle 56.

[0113] Referring to FIGS. 1A-1B and 6A-6B, as is apparent from the graphs 600 and 602, changing the orientation of the first and second prisms 52, 62 may further optimize the relative brightness and the brightness uniformity. In particular, the relative brightness and the brightness uniformity may be optimal when the first prisms 52 of the first prismatic film 50 extend away from the extended illumination source 21 and the second prisms 62 of the second prismatic film 60 extend toward the extended illumination source 21.

[0114] FIG. 7A shows a graph 700 depicting an axial brightness efficiency versus the brightness uniformity for the display system 300 (shown in FIGS. 1A, and IB) including identical first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB) having different tip radius TR (shown in FIG. 2), according to an embodiment of the present disclosure.

[0115] The brightness uniformity is expressed in the abscissa. The axial brightness efficiency is expressed in the ordinate in nits AV.

[0116] Referring to FIGS. 1 A-7A, the graph 700 includes a cluster of points A90. Each point in the cluster of points A90 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 90 degrees. Darker points in the cluster of points A90 denote greater tip radius TR of the first and second tips 55, 65.

[0117] Further, the graph 700 includes a cluster of points A80. Each point in the cluster of points A80 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 80 degrees. Darker points in the cluster of points A80 denote greater tip radius TR of the first and second tips 55, 65.

[0118] Further, the graph 700 includes a cluster of points A70. Each point in the cluster of points A70 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 70 degrees. Darker points in the cluster of points A70 denote greater tip radius TR of the first and second tips 55, 65.

[0119] Further, the graph 700 includes a cluster of points A60. Each point in the cluster of points A60 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apexangles 56, 66 of about 60 degrees. Darker points in the cluster of points A60 denote greater tip radius TR of the first and second tips 55, 65.

[0120] Referring to FIGS. 1A-1B and 7 A, in some embodiments, as the tip radius TR of the first and second tips 55, 65 increases, the brightness of the image 42 as perceived by the viewer and / or the brightness uniformity of the image 42 as perceived by the viewer decreases.

[0121] FIG. 7B shows a graph 702 depicting the axial brightness efficiency versus the brightness uniformity for the display system 300 (shown in FIGS. 1A, and IB) including identical first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB) having different valley radius VR (shown in FIG. 2), according to an embodiment of the present disclosure.

[0122] Referring to FIGS. 1A-7B, the graph 702 includes a cluster of points B90. Each point in the cluster of points B90 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 90 degrees. Darker points in the cluster of points B90 denote greater valley radius VR of the first and second valleys 53, 63.

[0123] Further, the graph 702 includes a cluster of points B80. Each point in the cluster of points B80 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 80 degrees. Darker points in the cluster of points B80 denote greater valley radius VR of the first and second valleys 53, 63.

[0124] Further, the graph 702 includes a cluster of points B70. Each point in the cluster of points B70 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 70 degrees. Darker points in the cluster of points B70 denote greater valley radius VR of the first and second valleys 53, 63.

[0125] Further, the graph 702 includes a cluster of points B60. Each point in the cluster of points B60 depicts the axial brightness efficiency and the brightness uniformity for the display system 300 including the first and second prismatic films 50, 60 having the respective first and second apex angles 56, 66 of about 60 degrees. Darker points in the cluster of points B60 denote greater valley radius VR of the first and second valleys 53, 63.

[0126] Referring to FIGS. 1A-1B and 7B, in some embodiments, as the valley radius VR of the first and second valleys 53, 63 increases, the brightness of the image 42 as perceived by the viewer increases and the brightness uniformity of the image 42 as perceived by the viewer decreases.

[0127] FIG. 8A shows a graph 800 depicting the axial brightness efficiency versus the brightness uniformity versus the tip radius TR (shown in FIG. 2) for the display system 300 (shown in FIGS. 1A, and IB) including the first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 60 degrees.

[0128] FIG. 8B shows a graph 802 depicting the axial brightness efficiency versus the brightness uniformity versus the valley radius VR (shown in FIG. 2) for the display system 300 (shown in FIGS. 1A, and IB) including the first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 60 degrees.

[0129] FIG. 9A shows a graph 900 depicting the axial brightness efficiency versus the brightness uniformity versus the tip radius TR (shown in FIG. 2) for the display system 300 (shown in FIGS. 1A, and IB) including the first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 74 degrees.

[0130] FIG. 9B shows a graph 902 depicting the axial brightness efficiency versus the brightness uniformity versus the valley radius VR (shown in FIG. 2) for the display system 300 (shown in FIGS. 1A, and IB) including the first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 74 degrees.

[0131] FIG. 10A shows a graph 1000 depicting the axial brightness efficiency versus the brightness uniformity versus the tip radius TR (shown in FIG. 2) for the display system 300 (shown in FIGS. 1A, and IB) including the first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 80 degrees.

[0132] FIG. 10B shows a graph 1002 depicting the axial brightness efficiency versus the brightness uniformity versus the valley radius VR (shown in FIG. 2) for the display system 300 (shown in FIGS. 1A, and IB) including the first and second prismatic films 50, 60 (shown in FIGS. 1A, and IB), according to an embodiment of the present disclosure. The first and second prismatic films 50, 60 have the respective first and second apex angles 56, 66 of about 80 degrees.

[0133] As is apparent from FIGS. 8A-10B, exact trends of the axial brightness efficiency versus the brightness uniformity versus the tip radius TR or the valley radius VR depend on the first and second apex angles 56, 66.

[0134] Referring to FIGS. 1A-10B, the first and second prismatic films 50, 60 disposed between the one or more light converting films 15 and the extended emission surface 22 may evenly distribute the emitted blue light 23 across the one or more light converting films 15. This may enhance the brightness efficiency and the brightness uniformity of the illumination 41 that reaches the display panel 40. Therefore, individual zones of the display panel 40 may not be visible, improving viewing experience for the viewer.

[0135] Furthermore, the backlight 200, 205 including the first and second prismatic films 50, 60 may be easier to fabricate compared to conventional solutions. In addition, the backlight 200, 205may enhance the brightness efficiency and the brightness uniformity without requiring any modification to an extended illumination source or registration of an LED array.

[0136] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

[0137] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

CLAIMS1. A backlight for providing illumination to a display panel configured to display an image to a viewer, the backlight comprising: an extended illumination source comprising one or more light sources and an extended emission surface and configured to emit a blue light through the extended emission surface toward the display panel, the emitted blue light comprising an emitted blue spectrum comprising an emitted blue full width at half maximum (FWHM); one or more light converting films disposed on the extended emission surface of the extended illumination source and comprising at least green and red emission spectra comprising corresponding non-overlapping green and red FWHMs, the one or more light converting films configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs; a first prismatic film disposed between the one or more light converting films and the extended emission surface, the first prismatic film comprising a first substrate and a plurality of first prisms disposed on the first substrate, the first prisms extending continuously along substantially a same first longitudinal direction and extending toward or away from the extended illumination source; and a second prismatic film disposed between the first prismatic film and the extended emission surface, the second prismatic film comprising a second substrate and a plurality of second prisms disposed on the second substrate, the second prisms extending continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extending toward or away from the extended illumination source.

2. The backlight of claim 1, wherein the first prisms extend away from the extended illumination source towards the viewer.

3. The backlight of claim 1, wherein the second prisms extend toward the extended illumination source away from the viewer.

4. The backlight of claim 1, wherein the backlight does not comprise any other prismatic film except the first and second prismatic films between the one or more light converting films and the extended illumination source.

5. The backlight of claim 1, wherein the emitted blue FWHM is disposed in a blue wavelength range extending from about 420 nm to about 480 nm, the green FWHM is disposed in a green wavelengthrange extending from about 490 nm to about 560 nm, and the red FWHM is disposed in a red wavelength range extending from about 590 nm to about 680 nm.

6. The backlight of claim 1 further comprising a third prismatic film disposed on the one or more light converting films opposite the first and second prismatic films and comprising a plurality of third prisms extending along substantially a same third longitudinal direction.

7. The backlight of claim 6 further comprising a fourth prismatic film disposed on the third prismatic film opposite the one or more light converting films and comprising a plurality of fourth prisms extending along substantially a same fourth longitudinal direction different from the third longitudinal direction.

8. The backlight of claim 1 further comprising a reflective polarizer disposed on the one or more light converting films opposite the first and second prismatic films and comprising a plurality of polymeric microlayers numbering at least 10 in total, each of the polymeric microlayers having an average thickness of less than about 500 nm, such that for a substantially normally incident light and for at least one visible wavelength in a visible wavelength range extending from about 420 nm to about 680 nm, the plurality of polymeric microlayers reflects more than about 60% of the incident light having an inplane first polarization state and transmits more than about 60% of the incident light having an in-plane orthogonal second polarization state.

9. A backlight for providing illumination to a display panel configured to display an image to a viewer, the backlight comprising: an extended illumination source comprising one or more light sources and an extended emission surface and configured to emit a blue light through the extended emission surface toward the display panel, the emitted blue light comprising an emitted blue spectrum comprising an emitted blue full width at half maximum (FWHM), the emitted blue FWHM disposed in a blue wavelength range extending from about 420 nm to about 480 nm; one or more light converting films disposed on the extended emission surface of the extended illumination source and comprising one or more of phosphor, fluorescent dye, and quantum dots, the one or more light converting films configured to receive the emitted blue light through the extended emission surface and convert at least portions of the received emitted blue light to at least green and red lights having respective green and red emission spectra comprising corresponding non-overlapping green and red FWHMs, the at least green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs, the green FWHM disposed in a green wavelength range extending from about 490 nm to about 560 nm, and the red FWHM disposed in a red wavelength range extending from about 590 nm to about 680 nm;a first prismatic film disposed between the one or more light converting films and the extended emission surface, the first prismatic film comprising a first substrate and a plurality of first prisms disposed on the first substrate, the first prisms extending continuously along substantially a same first longitudinal direction and extending toward or away from the extended illumination source, each of the first prisms has two first sides extending along the first longitudinal direction and extending from the first substrate and meeting at a first tip defining a first apex angle therebetween; and a second prismatic film disposed between the first prismatic film and the extended emission surface, the second prismatic film comprising a second substrate and a plurality of second prisms disposed on the second substrate, the second prisms extending continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extending toward or away from the extended illumination source, each of the second prisms has two second sides extending along the second longitudinal direction and extending from the second substrate and meeting at a second tip defining a second apex angle therebetween, wherein a magnitude of difference between the first apex angle and the second apex angle is greater than about 5 degrees.

10. A backlight for providing illumination to a display panel configured to display an image to a viewer, the backlight comprising: an extended illumination source comprising one or more light sources and an extended emission surface and configured to emit light through the extended emission surface toward the display panel; an optical diffuser disposed on the extended illumination source and having a diffuse optical transmittance of greater than about 10% for at least one wavelength of the emitted light ; a first prismatic film disposed between the optical diffuser and the extended emission surface, the first prismatic film comprising a first substrate and a plurality of first prisms disposed on the first substrate, the first prisms extending continuously along substantially a same first longitudinal direction and extending away from the extended illumination source toward the viewer; a second prismatic film disposed between the first prismatic film and the extended emission surface, the second prismatic film comprising a second substrate and a plurality of second prisms disposed on the second substrate, the second prisms extending continuously along substantially a same second longitudinal direction different from the first longitudinal direction and extending toward the extended illumination source away from the viewer; a third prismatic film disposed on the optical diffuser opposite the first prismatic film and comprising a plurality of third prisms extending along substantially a same third longitudinal direction; and a fourth prismatic film disposed on the third prismatic film opposite the optical diffuser and comprising a plurality of fourth prisms extending along substantially a same fourth longitudinal direction different from the third longitudinal direction.

11. The backlight of claim 10, wherein the first and second longitudinal directions are substantially orthogonal to each other, and the third and fourth longitudinal directions are substantially orthogonal to each other.

12. The backlight of claim 10, wherein the first and second substrates have respective first and second average thicknesses of greater than about 50 microns and less than about 400 microns.

13. The backlight of claim 12, wherein the first average thickness and the second average thickness are substantially equal.

14. The backlight of claim 10, wherein the backlight does not comprise any other prismatic film except the first and second prismatic films between the optical diffuser and the extended illumination source.

15. The backlight of claim 14, wherein at least one of the micro-LEDs is configured to emit a blue light having a blue wavelength in a blue wavelength range extending from about 420 nm to about 480 nm, at least one of the micro-LEDs is configured to emit a green light having a green wavelength in a green wavelength range extending from about 490 nm to about 560 nm, and at least one of the micro-LEDs is configured to emit a red light having a red wavelength in a red wavelength range extending from about 590 nm to about 680 nm.

Images