WO2025094080A1

WO2025094080A1 - Optical construction, backlight, and display system

Info

Publication number: WO2025094080A1
Application number: PCT/IB2024/060711
Authority: WO
Inventors: Matthew B. Johnson; Yu Hsin Lu
Original assignee: 3M Innovative Properties Co
Current assignee: 3M Innovative Properties Co
Priority date: 2023-10-31
Filing date: 2024-10-30
Publication date: 2025-05-08
Anticipated expiration: 2026-04-30

Abstract

A backlight includes an extended illumination source configured to emit light. The emitted light includes an emitted spectrum including respective non-overlapping first and second emitted FWHMs. The backlight includes one or more light converting films disposed on the extended emission surface including green and red emission spectra having corresponding non-overlapping green and red FWHMs. The backlight includes an optical film disposed on the one or more light converting films opposite the extended emission surface. For a substantially collimated incident light, a first incident angle of less than about 10 degrees, for each of mutually orthogonal in-plane first and second polarization states, the plurality of polymeric layers has an average optical transmittance of less than about 10% for wavelengths across the first emitted FWHM, and an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs.

Description

OPTICAL CONSTRUCTION, BACKLIGHT, AND DISPLAY SYSTEM

Technical Field

The present disclosure relates to a backlight and a display system including the backlight. The present disclosure further relates to an optical construction for use in the backlight.

Background

Typically, backlights may provide illumination to display panels configured to display an image on display systems. Nowadays, display panels in high-end display systems include quantum dot films and blue light-emitting diodes (LEDs) in the backlights of the display systems. The quantum dot films may enhance color gamut of the display systems and may provide more vivid colors. However, a quantum dots material used in the quantum dot films may be expensive, and therefore including the quantum dot films in the backlights may be a hurdle to their adoption in a mainstream segment of the display systems.

Summary

In a first aspect, the present disclosure provides a backlight for providing illumination to a display panel configured to display an image. 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 emitted light includes an emitted spectrum including first and second emitted peaks at respective first and second emitted peak wavelengths and respective non-overlapping first and second emitted full width at half maxima (FWHMs). The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source and including green and red emission spectra including respective green and red peaks at corresponding green and red peak wavelengths and corresponding non-overlapping green and red FWHMs. The green FWHM is disposed between the second and the red FWHMs. The one or more light converting fdms are configured to receive the emitted light through the extended emission surface and convert at least portions of the received emitted light to green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs. The backlight further includes an optical film disposed on the one or more light converting films opposite the extended emission surface and including a plurality of polymeric layers numbering at least 10 in total. Each of the polymeric layers has an average thickness of less than about 500 nanometers (nm). For a substantially collimated incident light, a first incident angle of less than about 10 degrees, and for each of mutually orthogonal in-plane first and second polarization states, the plurality of polymeric layers has an average optical transmittance of less than about 10% for wavelengths across the first emitted FWHM, and an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs. In a second aspect, the present disclosure provides a display system. The display system includes a display panel disposed on the backlight of the first aspect. The display panel is configured to receive the light emitted through the extended emission surface and display an image. The optical film is disposed between the display panel and the one or more light converting films.

In a third aspect, the present disclosure provides an optical construction for use in a backlight of a display system. The backlight is configured to provide illumination to a display panel of the display system configured to display an image. The optical construction includes one or more light converting films and an optical film disposed on the one or more light converting films. The optical film includes a plurality of polymeric layers numbering at least 10 in total. Each of the polymeric layers has an average thickness of less than about 500 nm. The optical construction further includes a bonding layer bonding the optical film to the one or more light converting films. For a substantially collimated incident light, a first incident angle of less than about 10 degrees, a second incident angle of no less than about 30 degrees, a violet wavelength range extending from about 390 nm to about 410 nm, a blue wavelength range extending from about 440 nm to about 460 nm, a green wavelength range extending from about 515 nm to about 540 nm, and a red wavelength range extending from about 600 nm to about 670 nm, and for each of mutually orthogonal in-plane first and second polarization states: the one or more light converting films convert at least portions of the incident light having wavelengths in the violet wavelength range to green and red lights having wavelengths in the respective green and red wavelength ranges, and has an optical transmittance of greater than about 50% for each of the blue, green and red wavelength ranges; and the plurality of polymeric layers has an average optical transmittance of less than about 10% for the violet wavelength range and the first incident angle, an average optical transmittance of greater than about 20% for the violet wavelength range and the second incident angle, and an average optical transmittance of greater than about 60% and less than about 95% for each of the blue, green, and red wavelength ranges and for each of the first and second incident angles.

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

Exemplary embodiments disclosed herein may be more completely understood in consideration of the following detailed description in connection with the following figures. The figures 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.

FIG. 1 shows a schematic sectional view of a display system, according to an embodiment of the present disclosure; FIG. 2A shows a schematic detailed sectional view of an optical film of the display system, according to an embodiment of the present disclosure;

FIG. 2B schematic detailed sectional view of a reflective polarizer of the display system, according to an embodiment of the present disclosure;

FIG. 3 shows a graph depicting an optical transmittance of the optical fdm versus wavelength for a substantially collimated incident light incident at different incident angles, according to an embodiment of the present disclosure; and

FIG. 4 shows a graph depicting an optical reflectance of a back reflector versus wavelength, according to an embodiment of the present disclosure.

Detailed Description

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.

In the following disclosure, the following definitions are adopted.

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.

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).

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.

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.

As used herein, the terms “first” and “second” are used as identifiers. Therefore, such terms should not be constmed 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.

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

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.

Typically, backlights may provide illumination to display panels configured to display an image on conventional display systems. Nowadays, display panels in high-end display systems include quantum dot films and blue light-emitting diodes (LEDs) in the backlights of the conventional display systems. The quantum dot films may enhance color gamut of the display systems and may provide more vivid colors. However, a quantum dots material used in the quantum dot films may be expensive, and therefore including the quantum dot films in the backlights may be a hurdle to their adoption in a mainstream segment of the display systems.

The present disclosure relates to a backlight, a display system including the backlight, and an optical construction for use in the backlight.

The backlight provides an illumination to a display panel configured to display an image. 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 emitted light includes an emitted spectrum including first and second emitted peaks at respective first and second emitted peak wavelengths and respective non-overlapping first and second emitted full width at half maxima (FWHMs). The backlight further includes one or more light converting films disposed on the extended emission surface of the extended illumination source and including green and red emission spectra including respective green and red peaks at corresponding green and red peak wavelengths and corresponding non-overlapping green and red FWHMs. The green FWHM is disposed between the second and the red FWHMs. The one or more light converting films are configured to receive the emitted light through the extended emission surface and convert at least portions of the received emitted light to green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs. The backlight further includes an optical film disposed on the one or more light converting films opposite the extended emission surface and including a plurality of polymeric layers numbering at least 10 in total. Each of the polymeric layers has an average thickness of less than about 500 nanometers (nm). For a substantially collimated incident light, a first incident angle of less than about 10 degrees, and for each of mutually orthogonal in-plane first and second polarization states, the plurality of polymeric layers has an average optical transmittance of less than about 10% for wavelengths across the first emitted FWHM, and an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs.

The emitted light may include a blue light, and a violet light in addition to the blue light. Therefore, the emitted FWHM of the emitted spectrum may lie in a violet wavelength range as well as a blue wavelength range. The one or more light converting fdms may have a better efficiency to convert the violet light in the violet wavelength range to green and red lights than converting the blue light in the blue wavelength range to the green and red lights. Specifically, the one or more light converting films may include quantum dots material. The quantum dots material may have a high absorption rate for the violet light in the violet wavelength range. Therefore, the amount of the quantum dots material required to convert the violet light in the violet wavelength range may be substantially low. Thus, the extended illumination source, emitting the violet light in addition to the blue light, may reduce the amount of the quantum dots material required in the one or more light converting films to convert the emitted light including the blue light and the violet light to the green and red lights. This may reduce the cost of the one or more light converting films of the backlight. Further, the optical fdm disposed on the one or more light converting films may reduce the violet light in the violet wavelength range that reaches eyes of a viewer. Specifically, the optical film may reflect a portion of the violet light in the violet wavelength range which is not absorbed by the quantum dots material to reduce the violet light in the violet wavelength range that reaches the eyes of the viewer.

Therefore, the backlight of the present disclosure may reduce the use of the quantum dots material in the one or more light converting films in order to reduce the cost of the display systems, while preventing the violet light in the violet wavelength range to reach the eyes of the viewer.

Referring now to figures, FIG. 1 is a schematic sectional exploded view of a display system 300, according to an embodiment of the present disclosure.

The display system 300 defines mutually orthogonal x, y, and z-axes. The x and y-axes are inplane 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.

The display system 300 includes a display panel 40. The display panel 40 is configured to display an image 42. The display panel 40 is disposed on a backlight 200. In some embodiments, the display system 300 includes the backlight 200. The backlight 200 provides an illumination 41 to the display panel 40. Specifically, the backlight 200 is configured to provide the illumination 41 to the display panel 40 of the display system 300 configured to display the image 42. In other words, the display panel 40 is configured to receive the illumination 41 from the backlight 200 and display the image 42. In some embodiments, the display panel 40 includes a liquid crystal display (LCD) panel.

The backlight 200 includes an extended illumination source 21. The extended illumination source 21 includes one or more light sources 20 and an extended emission surface 22. The extended illumination source 21 is configured to emit light 23 through the extended emission surface 22 toward the display panel 40. In some embodiments, the display panel 40 is configured to receive the light 23 emitted through the extended emission surface 22 and display the image 42. In some embodiments, the light 23 may be interchangeably referred to as “the emitted light 23”.

In some embodiments, the one or more light sources 20 includes at least a first light source 20 in the one or more light sources 20 and at least a second light source 20 in the one or more light sources 20. The at least the first light source 20 is configured to emit a first emitted light 23v and the at least the second light source 20 is configured to emit a second emitted light 23b. Accordingly, in some embodiments, the emitted light 23 from the one or more light sources 20 includes the first emitted light 23v emitted from the at least the first light source 20 in the one or more light sources 20 and the second emitted light 23b emitted from the at least the second light source in the one or more light sources 20. Thus, the emitted light 23 and may be referred to as “the emitted light 23v, 23b”.

In some embodiments, the at least the first light source 20 is a violet light source and the first emitted light 23v is a violet light. Therefore, the first emitted light 23v may be interchangeably referred to as “the violet light 23v”. In some embodiments, the at least the second light source 20 is a blue light source and the second emitted light 23b is a blue light. Therefore, the second emitted light 23b may be interchangeably referred to as “the blue light 23b”. In some embodiments, the violet light 23v has a violet wavelength disposed in a violet wavelength range. Similarly, the blue light 23b has a blue wavelength disposed in a blue wavelength range. In some embodiments, the violet wavelength range extends from about 390 nanometers (nm) to about 410 nm and the blue wavelength range extends from about 440 nm to about 460 nm.

In some embodiments, the extended illumination source 21 further includes a lightguide 24 for receiving a light 24a from the one or more light sources 20 and propagating the received light 24a therein along a length and a width of the lightguide 24. In some embodiments, the length of the lightguide 24 extends substantially along the x-axis. In some embodiments, the width of the lightguide

24 extends substantially along the y-axis.

The received light 24a propagates in the lightguide 24 as a propagating light 24b. Further, the propagating light 24b exits the lightguide 24 through an exit surface 25 of the lightguide 24 as an exiting light 24c. In some embodiments, the exit surface 25 is substantially co-extensive in length and width with the extended emission surface 22. In some embodiments, the length of the exit surface 25 extends substantially along the x-axis. In some embodiments, the width of the exit surface 25 extends substantially along the y-axis.

In some embodiments, the exiting light 24c exits the extended illumination source 21 through the extended emission surface 22 as the emitted light 23v, 23b. In some embodiments, the exit surface

25 of the lightguide 24 includes the extended emission surface 22.

In some embodiments, the extended illumination source 21 further includes a back reflector 27. In some embodiments, the back reflector 27 is substantially co-extensive in length and width with the extended emission surface 22. The back reflector 27 may be configured to reflect any light that exits the lightguide 24 and reaches the back reflector 27 back toward the lightguide 24. 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 lightguide 24 is disposed between the extended emission surface 22 and the back reflector 27.

In some embodiments, the back reflector 27 is spaced apart from the extended emission surface 22. In some embodiments, the extended emission surface 22 and the back reflector 27 define an optical cavity 28 therebetween. In some embodiments, the one or more light sources 20 are disposed proximate one or more edge surfaces 26 of the lightguide 24. In some embodiments, the one or more light sources 20 are disposed in the optical cavity 28.

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 are configured to receive the emitted light 23v, 23b through the extended emission surface 22. The one or more light converting films 15 are configured to convert at least portions of the received emitted light 23v, 23b to green and red lights 10g, lOr. The green and red lights 10g, lOr have respective green and red wavelengths.

In the illustrated embodiment of FIG. 1, the one or more light converting films 15 include a green-light converting film 15g and a red-light converting film 15r. In some cases, “the one or more light converting fdms 15” may be interchangeably referred to as “the light converting films 15g, 15r”.

In some embodiments, the green-light converting film 15g is configured to receive the emitted light 23 through the extended emission surface 22 and convert at least a portion of the received emitted light 23 to the green light 10g having the green wavelength. Similarly, the red-light converting film 15r is configured to receive the emitted light 23 through the extended emission surface 22 and convert at least a portion of the received emitted light 23 to the red light lOr having the red wavelength.

The backlight 200 further includes an optical film 30. The optical film 30 is disposed on the one or more light converting films 15 opposite to the extended emission surface 22. Further, in the illustrated embodiment of FIG. 1, the optical film 30 is disposed between the display panel 40 and the one or more light converting films 15. In some embodiments, the optical film 30 is substantially coextensive in length and width with the display panel 40 and the one or more light converting films 15.

In some embodiments, the backlight 200 further includes a bonding layer 70 bonding the optical film 30 to the one or more light converting films 15. The bonding layer 70 may be interchangeably referred to as “the first bonding layer 70”. Therefore, in other words, the optical film 30 is bonded to the one or more light converting films 15 via the first bonding layer 70.

In some embodiments, the backlight 200 further includes at least one barrier layer (not shown) disposed on the one or more light converting films 15. In some embodiments, the at least one barrier layer includes a pair of barrier layers, and the one or more light converting films 15 are disposed between the pair of barrier layers. In some embodiments, the at least one barrier layer at least partially or entirely encapsulates the one or more light converting films 15. In some embodiments, the at least one barrier layer further at least partially or entirely encapsulates the first bonding layer 70.

In some embodiments, the at least one barrier layer may be attached to the one or more light converting films 15 via a chemical process. In some embodiments, the at least one barrier layer may be attached to the one or more light converting films 15 via cross-linking by an ultraviolet (UV) process or a thermal curing process. In some embodiments, the at least one barrier layer is a moisture barrier layer. The at least one barrier layer may reduce moisture transmission to the one or more light converting films 15. The at least one barrier layer may have a moisture vapor transmission rate (MVTR) of less than about 1 gm/m²/day, less than about 0.01 gm/m²/day, or less than about 0.001 gm/m²/day measured at 50 degrees Celsius (°C), for example using Mocon.

In some embodiments, the one or more light converting films 15, the optical film 30, and the first bonding layer 70 may be collectively referred to as an optical construction 400 as indicated in FIG. 1. The optical construction 400 is used in the backlight 200 of the display system 300.

In some embodiments, the backlight 200 further includes an optical diffuser 80 disposed on the optical film 30 opposite the one or more light converting films 15. In some embodiments, the optical film 30 is bonded to the optical diffuser 80 via a second bonding layer 71.

In some embodiments, the backlight 200 further includes a first prismatic film 90. The first prismatic film 90 is disposed on the optical fdm 30 opposite the one or more light converting films 15. The first prismatic film 90 includes a plurality of first prisms 91. In some embodiments, the plurality of first prisms 91 extends along substantially a same first longitudinal direction. In some embodiments, the first longitudinal direction extends substantially along the y-axis.

In some embodiments, the backlight 200 further includes a second prismatic film 92 disposed on the first prismatic film 90 opposite the optical film 30. The second prismatic film 92 includes a plurality of second prisms 93. The plurality of second prisms 93 extends along substantially a same second longitudinal direction different from the first longitudinal direction. In some embodiments, the second longitudinal direction extends substantially along the x-axis.

In some embodiments, the optical diffuser 80 is disposed between the first prismatic film 90 and the optical film 30. In some embodiments, the optical diffuser 80 is bonded to the first prismatic film 90 via a third bonding layer 72.

In the illustrated embodiment of FIG. 1, the backlight 200 further includes a reflective polarizer 100 disposed on the optical film 30 opposite the one or more light converting films 15. In some embodiments, the reflective polarizer 100 is bonded to the display panel 40 via a fourth bonding layer 73. In some embodiments, each of the first, second, third, and fourthbonding layers 70, 71, 72, 73 may include an optically clear adhesive (OCA).

FIG. 2A is a schematic detailed sectional view of the optical film 30, according to an embodiment of the present disclosure.

The optical film 30 includes a plurality of polymeric layers 43. The plurality of polymeric layers 43 numbers at least 10 in total. In some embodiments, the plurality of polymeric layers 43 numbers at least 20, at least 50, at least 75, at least 100, at least 150, at least 200, at least 250, or at least 300 in total.

Each of the polymeric layers 43 has an average thickness t of less than about 500 nm. The term “the average thickness f ’, 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 layers 43. In some embodiments, each of the polymeric layers 43 has the average thickness t of less than about 400 nm, less than about 300 nm, or less than about 200 nm. In some embodiments, the plurality of polymeric layers 43 includes a plurality of alternating polymeric first and second layers 31, 32. The plurality of alternating polymeric first and second layers 31, 32 is stacked along a thickness direction of the optical film 30. In some embodiments, the thickness direction extends substantially along the z-axis.

In some embodiments, the optical film 30 further includes at least one skin layer 33 disposed on the plurality of polymeric layers 43. In some embodiments, the at least one skin layer 33 has an average thickness st of greater than about 500 nm. The term “the 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. In some embodiments, the at least one skin layer 33 has the average thickness st of greater than about 750 nm, greater than about 1000 nm, greater than about 1500 nm, or greater than about 2000 nm.

In the illustrated embodiment of FIG. 2 A, the at least one skin layer 33 includes a pair of skin layers 33, and the plurality of polymeric layers 43 is disposed between the pair of skin layers 33. The at least one skin layer 33 may protect the plurality of polymeric layers 43 and may also provide mechanical stability to the optical film 30. In some cases, the at least one skin layer 33 may act as a protective boundary layer (PBL).

FIG. 2A further illustrates a substantially collimated incident light 34a incident on the optical film 30. In some embodiments, the substantially collimated incident light 34a is incident on the optical film 30 at a first incident angle al. The first incident angle al is less than about 10 degrees. In some embodiments, the first incident angle al is less than about 8 degrees, less than about 6 degrees, less than about 4 degrees, less than about 2 degrees, or less than about 1 degree. In some embodiments, the first incident angle al is about 0 degree.

FIG. 2A also illustrates a substantially collimated incident light 34b incident on the optical film 30 at a second incident angle a2 of no less than about 20 degrees. In some embodiments, the second incident angle a2 is no less than about 25 degrees, no less than about 30 degrees, no less than about 35 degrees, no less than about 40 degrees, no less than about 45 degrees, no less than about 50 degrees, no less than about 55 degrees, or no less than about 60 degrees. In some embodiments, the second incident angle a2 is about 40 degrees. In some embodiments, the second incident angle a2 is about 60 degrees.

FIG. 2B is a schematic detailed sectional view of the reflective polarizer 100, according to an embodiment of the present disclosure.

In some embodiments, the reflective polarizer 100 includes a plurality of polymeric microlayers 143. The plurality of polymeric microlayers 143 numbers at least 10 in total. In some embodiments, the plurality of polymeric microlayers 143 numbers at least at least 20, at least 50, at least 75, at least 100, at least 150, at least 200, at least 250, at least 300, or at least 400 in total.

In some embodiments, each of the polymeric microlayers 143 has an average thickness tl of less than about 500 nm. The term “the average thickness tl”, 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 143. In some embodiments, each of the polymeric microlayers 143 has the average thickness tl of less than about 400 nm, less than about 350 nm, less than about 300 nm, less than about 250 nm, or less than about 200 nm.

In some embodiments, the plurality of polymeric microlayers 143 includes a plurality of alternating polymeric first and second microlayers 131, 132. The plurality of alternating polymeric first and second microlayers 131, 132 is stacked along the thickness direction of the reflective polarizer 100 (i.e., substantially along the x-axis).

In some embodiments, the reflective polarizer 100 further includes at least one skin layer 133 disposed on the plurality of polymeric microlayers 143. In some embodiments, the at least one skin layer 133 has an average thickness stl of greater than about 500 nm. The term “the average thickness st 1”, 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 133. In some embodiments, the at least one skin layer 133 has the average thickness stl of greater than about 750 nm, greater than about 1000 nm, greater than about 1500 nm, or greater than about 2000 nm.

In the illustrated embodiment of FIG. 2B, the at least one skin layer 133 includes a pair of skin layers 133, and the plurality of polymeric microlayers 143 is disposed between the pair of skin layers 133. The at least one skin layer 133 may protect the plurality of polymeric microlayers 143 and may also provide mechanical stability to the reflective polarizer 100. In some cases, the at least one skin layer 133 may act as a protective boundary layer (PBL).

FIG. 2B further illustrates a substantially normally incident light 35 incident on the reflective polarizer 100, i.e., the incident light 35 is incident on the reflective polarizer 100 at an angle of 0 degree with respect to a normal to the reflective polarizer 100.

FIG. 3 is a graph 350 depicting an optical transmittance of the plurality of polymeric layers 31, 32 of the optical film 30 (shown in FIGS. 1 and 2A) versus wavelength for the substantially collimated incident light 34a, 34b (shown in FIG. 2A) incident at the first and second incident angles al, a2 (shown in FIG. 2A), respectively, according to an embodiment of the present disclosure.

The graph 350 further depicts emission spectrum versus wavelength for the emitted light 23v, 23b (shown in FIG. 1) emitted from the one or more light sources 20 (shown in FIG. 1). The graph 350 further depicts emission spectra versus wavelength for the one or more light converting fdms 15 shown in FIG. 1.

Wavelength is expressed in nanometers (nm) in the abscissa. The optical transmittance is expressed as a transmittance percentage in the left ordinate, while the emission intensity is expressed in arbitrary units (a.u.) in the right ordinate.

The emitted light 23v, 23b includes an emitted spectrum 50. The emitted spectrum 50 includes first and second emitted peaks 5 Iv, 5 lb at respective first and second emitted peak wavelengths 52v, 52b and respective non-overlapping first and second emitted full width at half maximums (FWHMs) 53v, 53b.

Specifically, the first emitted light 23v includes a first emitted spectrum 50v in the emitted spectrum 50 and the second emitted light 23b includes a second emitted spectrum 50b in the emitted spectrum 50. The first emitted spectrum 50v includes the first emitted peak 5 Iv at the first emitted peak wavelength 52v and the first emitted FWHM 53v. Similarly, the second emitted spectrum 50b includes the second emitted peak 5 lb at the second emitted peak wavelength 52b and the second emitted FWHM 53b. As is apparent from the graph 350, the first emitted light 23v does not include any wavelengths from the second emitted FWHM 53b and the second emitted light 23b does not include any wavelengths from the first emitted FWHM 53v. Therefore, the first and second emitted FWHM 53v, 53b are nonoverlapping.

In some embodiments, the first emitted peak wavelength 52v is less than about 420 nm. In some embodiments, the first emitted peak wavelength 52v is less than about 415 nm, less than about 410 nm, or less than about 405 nm. In the illustrated example of FIG. 3, the first emitted peak wavelength 52v is about 400 nm.

In some embodiments, the first emitted FWHM 53v is at least 5 nm wide. In some embodiments, the first emitted FWHM 53v is at least 10 nm or at least 15 nm wide. In some embodiments, the first emitted FWHM 53v is less than about 40 nm wide. In some embodiments, the first emitted FWHM 53v is less than about 35 nm, less than about 30 nm, less than about 25 nm, or less than about 20 nm wide. In the illustrated example of FIG. 3, the first emitted FWHM 53v is disposed between about 393 nm and about 409 nm, and is about 16 nm wide.

In some embodiments, the second emitted peak wavelength 52b is greater than about 420 nm. In some embodiments, the second emitted peak wavelength 52b is greater than about 425 nm, greater than about 430 nm, greater than about 435 nm, greater than about 440 nm, greater than about 445 nm, or greater than about 450 nm. In the illustrated example of FIG. 3, the second peak wavelength 52b is about 452 nm.

In some embodiments, the second emitted FWHM 53b is at least 5 nm wide. In some embodiments, the second emitted FWHM 53b is at least 10 nm or at least 15 nm wide. In some embodiments, the second emitted FWHM 53b is less than about 40 nm wide. In some embodiments, the second emitted FWHM 53b is less than about 35 nm, less than about 30 nm, less than about 25 nm, or less than about 20 nm wide. In the illustrated example of FIG. 3, the second emitted FWHM 53b is disposed between about 444 nm and about 462 nm, and is about 18 nm wide.

In some embodiments, the first emitted peak wavelength 52v is less than the second emitted peak wavelength 52b by at least 10 nm. In some embodiments, the first emitted peak wavelength 52v is less than the second emitted peak wavelength 52b by at least 15 nm, by at least 20 nm, by at least 25 nm, by at least 30 nm, by at least 35 nm, or by at least 40 nm. In the illustrated example of FIG. 3, the first emitted peak wavelength 52v is less than the second emitted peak wavelength 52b by about 52 nm.

The one or more light converting films 15 include green and red emission spectra 50g, 50r including respective green and red peaks 51g, 51r at corresponding green and red peak wavelengths 52g, 52r and corresponding non-overlapping green and red FWHMs 53g, 53r. Specifically, the green emission spectrum 50g includes the green peak 51g at the green peak wavelength 52g and the green FWHM 53g. The red emission spectrum 50r includes the red peak 5 Ir at the red peak wavelength 52r and the red FWHM 53r. Further, the green and red FWHMs 53g, 53r are non-overlapping. As is apparent from the graph 350, the green FWHM 53g is disposed between the second and red FWHMs 53b, 53r.

The green and red wavelengths are disposed in the respective green and red FWHMs 53g, 53r. Specifically, the green wavelength of the green light 10g (shown in FIG. 1) is disposed in the green FWHM 53g and the red wavelength of the red light lOr (shown in FIG. 1) is disposed in the red FWHM 53r.

In some embodiments, the green peak wavelength 52g is between about 490 nm and about 560 nm. In the illustrated example of FIG. 3, the green peak wavelength 52g is about 527 nm. In some embodiments, the second emitted peak wavelength 52b is less than the green peak wavelength 52g by at least 100 nm. In some embodiments, the second emitted peak wavelength 52b is less than the green peak wavelength 52g by at least 95 nm, by at least 90 nm, by at least 85 nm, by at least 80 nm, by at least 75 nm, or by at least 70 nm. In the illustrated example of FIG. 3, the second emitted peak wavelength 52b is less than the green peak wavelength 52g by about 75 nm.

In some embodiments, the green FWHM 53 g is disposed in a green wavelength range extending from about 490 nm to about 560 nm. In some embodiments, the green wavelength range extends from about 515 nm to about 540 nm. In some embodiments, the second emitted FWHM 53b does not overlap the green FWHM 53 g.

In some embodiments, the green FWHM 53g is at least 5 nm wide. In some embodiments, the green FWHM 53g is at least 10 nm, at least 15 nm, or at least 20 nm wide. In some embodiments, the green FWHM 53g is less than about 50 nm wide. In some embodiments, the green FWHM 53g is less than about 45 nm, less than about 40 nm, less than about 35 nm, less than about 30 nm, or about less than about 25 nm wide. In the illustrated example of FIG. 3, the green FWHM 53g is disposed between about 516 nm and about 537 nm, and is about 21 nm wide.

In some embodiments, the red peak wavelength 52r is between about 590 nm and about 670 nm. In the illustrated example of FIG. 3, the red peak wavelength 52r is about 627 nm. In some embodiments, the red FWHM 53r is disposed in a red wavelength range extending from about 590 nm to about 670 nm. In some embodiments, the red wavelength range extends from about 600 nm to about 670 nm.

In some embodiments, the red FWHM 53r is at least 5 nm wide. In some embodiments, the red FWHM 53r is at least 10 nm, at least 15 nm, at least 20 nm, at least 25 nm, at least 30 nm, at least 35 nm, or at least 40 nm wide. In some embodiments, the red FWHM 53r is less than about 80 nm wide. In some embodiments, the red FWHM 53r is less than about 75 nm, less than about 70 nm, less than about 65 nm, less than about 60 nm, less than about 55 nm, less than about 50 nm, or less than about 45 nm wide. In the illustrated example of FIG. 3, the red FWHM 53r is disposed between about 607 nm and about 648 nm, and is about 41 nm wide.

Table 1 provided below summarizes the first emitted peak wavelength 52v of the first emitted peak 5 Iv of the first emitted spectrum 50v of the first emitted light 23v from the one or more light sources 20, the second peak wavelength 52b of the second emitted peak 51b of the second emitted spectrum 50b of the second emitted light 23b from the one or more light sources 20, the green peak wavelength 52g of the green peak 51g of the green emission spectrum 50g of the green-light converting film 15g, and the red peak wavelength 52r of the red peak 51r of the red emission spectrum 50r of the red-light converting film 15r.

Table 1

The graph 350 includes a curve 302 depicting an optical transmittance of the optical film 30 for the substantially collimated incident light 34a (shown in FIG. 2A) incident at the first incident angle al (shown in FIG. 2A) of less than about 10 degrees (e.g., 0 degrees) and for each of mutually orthogonal in-plane first and second polarization states p, s. In some embodiments, the first polarization state p extends substantially along the x-axis and the second polarization state s extends substantially along the y-axis. In some embodiments, the first polarization state p may correspond to a p-polarization state, while the second polarization state s may correspond to a s-polarization state.

Referring to FIGS. 2A and 3, as is apparent from the curve 302, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the optical film 30 has an average optical transmittance of less than about 10% for wavelengths across the first emitted FWHM 53v. In other words, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of less than about 10% for wavelengths across the first emitted FWHM 53v.

In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of less than about 8%, less than about 6%, less than about 4%, less than about 2%, less than about 1%, less than about 0.5%, or less than about 0.1% for wavelengths across the first emitted FWHM 53v.

In the illustrated examples of FIGS. 2A and 3, for the substantially collimated incident light 34a, the first incident angle al of about 0 degree, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has an average optical transmittance of about 0% for wavelengths across the first emitted FWHM 53v.

In some embodiments, for the substantially collimated incident light 34a and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of less than about 10% for the violet wavelength range and the first incident angle al.

Thus, the optical film 30 may substantially block the substantially collimated incident light 34a incident at the first incident angle al for each of the first and second polarization states across the first emitted FWHM 53v and/or across the violet wavelength range. Therefore, the optical film 30 may substantially reflect the first emitted light 23v incident at the first incident angle al. Thus, the optical film 30 may reduce optical transmission of the violet light 23v to the display panel 40, thereby reducing exposure of the violet light 23v to eyes of a viewer.

Further, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the optical film 30 has an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs 53b, 53g, 53r. In other words, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs 53b, 53g, 53r.

In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80%, and less than about 90% or less than about 85% for each of the second, green, and red FWHMs 53b, 53g, 53r.

In the illustrated examples of FIGS. 2 A and 3, for the substantially collimated incident light 34a, the first incident angle al of about 0 degree, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has an average optical transmittance of about 84.5% for the second emitted FWHM 53b, an average optical transmittance of about 89.5% for the green FWHM 53g, and an average optical transmittance of about 90.3% for the red FWHM 53r.

Thus, the optical film 30 may substantially transmit the substantially collimated incident light 34a incident at the first incident angle al for each of the first and second polarization states across the second, green, and red FWHMs 53b, 53g, 53r. Therefore, the optical film 30 may substantially transmit the second, green, and red lights 10b, 10g, lOr incident at the first incident angle al.

Further, for the substantially collimated incident light 34a incident at the first incident angle al and for each of the first and second polarization states, the optical film 30 may be substantially more optically transmissive across the second, green, and red FWHMs 53b, 53g, 53r than across the first emitted FWHM 53v.

The graph 350 further includes curves 304 and 306 depicting optical transmittances of the optical film 30 for the substantially collimated incident light 34b (shown in FIG. 2A) incident at different second incident angles a2 and for each of the first and second polarization states p, s. Specifically, the curve 304 depicts the optical transmittance of the optical film 30 for the substantially collimated incident light 34b incident at the second incident angle a2 of about 40 degrees and for each of the first and second polarization states p, s. Further, the curve 306 depicts the optical transmittance of the optical film 30 for the substantially collimated incident light 34b incident at the second incident angle a2 of about 60 degrees and for each of the first and second polarization states p, s.

In some embodiments, for the substantially collimated incident light 34b, the second incident angle a2 of no less than about 20 degrees, and for each of the first and second polarization states p, s, the optical film 30 has an average optical transmittance of greater than about 20% for wavelengths across the first emitted FWHM 53v. In other words, for the substantially collimated incident light 34b, the second incident angle a2 of no less than about 20 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 20% for wavelengths across the first emitted FWHM 53v.

In some embodiments, for the substantially collimated incident light 34b, for the second incident angle a2 of no less than about 20 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 25%, greater than about 30%, greater than about 35%, or greater than about 40% for the wavelengths across the first emitted FWHM 53v.

Further, for the substantially collimated incident light 34b and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has an average optical transmittance of greater than about 20% for the violet wavelength range and the second incident angle a2 of no less than 30 degrees. In some embodiments, for the substantially collimated incident light 34b and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 25%, greater than about 30%, greater than about 35%, or greater than about 40% for the violet wavelength range and the second incident angle a2 of no less than 30 degrees.

As is apparent from the curve 304, for the substantially collimated incident light 34b, for the second incident angle a2 of about 40 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of about 39.7 % for the wavelengths across the first emitted FWHM 53v.

Further, in some embodiments, for the substantially collimated incident light 34b, the second incident angle a2 of no less than about 20 degrees, and for each of the first and second polarization states p, s, the optical film 30 has an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs 53b, 53g, 53r. In other words, for the substantially collimated incident light 34b, the second incident angle a2 of no less than about 20 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs 53b, 53g, 53r. In some embodiments, for the substantially collimated incident light 34b, for the second incident angle a2 of no less than about 20 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average transmittance of greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80%, and less than about 90% or less than about 85% for each of the second, the green, and the red FWHMs 53b, 53g, 53r.

As is apparent from the curve 304, for the substantially collimated incident light 34b, for the second incident angle a2 of about 40 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has an average optical transmittance of about 82.5 % for the second emitted FWHM 53b, an average optical transmittance of about 84.7 % for the green FWHM 53g, and an average optical transmittance of about 85.8 % for the red FWHM 53r.

Thus, for the substantially collimated incident light 34b incident at the second incident angle a2 and for each of the first and second polarization states, the optical film 30 may be more optically transmissive across the second, green, and red FWHMs 53b, 53g, 53r than across the first emitted FWHM 53v. Therefore, the optical film 30 may substantially transmit the second, green, and red lights 10b, 10g, lOr incident at the second incident angle a2.

Referring to the curves 302, 304, 306, for the substantially collimated incident light 34b, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 60% and less than about 95% for each of the blue, green, and red wavelength ranges and for each of the first incident angle al of less than about 10 degrees and the second incident angle a2 of no less than about 30 degrees.

In some embodiments, for the substantially collimated incident light 34b, the second incident angle a2 of no less than about 30 degrees, and for each of the first and second polarization states p, s, the optical film 30 has an average optical transmittance of greater than about 50% and less than about 95% for each of the first, second, green, and red FWHMs 53v, 53b, 53g, 53r. In other words, for the substantially collimated incident light 34b, the second incident angle a2 of no less than about 30 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 50% and less than about 95% for each of the first, second, green, and red FWHMs 53v, 53b, 53g, 53r.

In some embodiments, for the substantially collimated incident light 34b, for the second incident angle a2 of no less than about 30 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has the average optical transmittance of greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, or greater than about 80%, and less than about 90% or less than about 85% for each of the first, second, green, and red FWHMs 53v, 53b, 53g, 53r.

As is apparent from the curve 306, for the substantially collimated incident light 34b, for the second incident angle a2 of about 60 degrees, and for each of the first and second polarization states p, s, the plurality of polymeric layers 31, 32 has an average optical transmittance of about 72.7% for the first emitted FWHM 53v, an average optical transmittance of about 77.2% for the second emitted FWHM 53b, an average optical transmittance of about 78.5% for the green FWHM 53g, and an average optical transmittance of about 80.4% for the red FWHM 53r.

Thus, for the substantially collimated incident light 34b incident at the second incident angle a2 and for each of the first and second polarization states, the optical film 30 may be substantially optically transmissive across the first, second, green, and red FWHMs 53v, 53b, 53g, 53r.

Table 2 provided below summarizes average optical transmittances of the optical film 30 for a substantially collimated incident light incident at different incident angles (e.g., the first and second incident angles al, a2).

Table 2

where, T30(0) refers to the average optical transmittance of the optical film 30 for the substantially collimated incident light incident at an incident angle of about 0 degree;

T30(20) refers to the average optical transmittance of the optical film 30 for the substantially collimated incident light incident at an incident angle of about 20 degrees;

T30(40) refers to the average optical transmittance of the optical film 30 for the substantially collimated incident light incident at an incident angle of about 40 degrees; and

T30(60) refers to the average optical transmittance of the optical film 30 for the substantially collimated incident light incident at an incident angle of about 60 degrees.

In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have an average optical absorption of greater than about 20% for the wavelengths across the first emitted FWHM 53v. In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have the average optical absorption of greater than about 30%, greater than about 40%, greater than about 50%, greater than about 60%, or greater than about 70% for the wavelengths across the first emitted FWHM 53v.

In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have the optical absorption of greater than about 20% for the first emitted peak wavelength 52v. In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have the optical absorption of greater than about 30%, greater than about 40%, greater than about 50%, greater than about 60%, or greater than about 70% for the first emitted peak wavelength 52v.

Thus, for the substantially collimated incident light 34a incident at the first incident angle al and for each of the first and second polarization states, the one or more light converting films 15 may have a good optical absorption for the wavelengths across the first emitted FWHM 53v. In other words, for the substantially collimated incident light 34a incident at the first incident angle al and for each of the first and second polarization states, the one or more light converting films 15 may have a good optical absorption for the violet light 23v.

Further, in some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have an average optical transmittance of greater than about 50% for the wavelengths across the second emitted FWHM 53b. In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have the average optical transmittance of greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, or greater than about 85% for the wavelengths across the second emitted FWHM 53b.

In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have an optical transmittance of greater than about 50% for the second emitted peak wavelength 52b. In some embodiments, for the substantially collimated incident light 34a, the first incident angle al, and for each of the first and second polarization states p, s, the one or more light converting films 15 have the optical transmittance of greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, or greater than about 85% for the second emitted peak wavelength 52b.

Thus, for the substantially collimated incident light 34a incident at the first incident angle al and for each of the first and second polarization states, the optical film 30 may be substantially optically transmissive across the second emitted FWHM 53b. In other words, for the substantially collimated incident light 34a incident at the first incident angle al and for each of the first and second polarization states, the optical film 30 may be substantially optically transmissive for the blue light 23b.

As discussed above, the one or more light converting films 15 are configured to convert at least portions of the received emitted light 23v, 23b to the green and red lights 10g, lOr (shown in FIG. 1) having respective green and red wavelengths. Specifically, in some embodiments, for the substantially collimated incident light 34a, the first incident angle al of less than about 10 degrees, and for each of the first and second polarization states p, s, the one or more light converting films 15 convert at least portions of the substantially collimated incident light 34a having wavelengths in the violet wavelength range to the green and red lights 10g, lOr having wavelengths in the respective green and red wavelength ranges.

Further, in some embodiments, for the substantially collimated incident light 34a, the first incident angle al of less than about 10 degrees, and for each of the first and second polarization states p, s, the one or more light converting films have an optical transmittance of greater than about 50% for each of the blue, green, and red wavelength ranges. In some embodiments, for the substantially collimated incident light 34a, the first incident angle al of less than about 10 degrees, and for each of the first and second polarization states p, s, the one or more light converting films 15 have the optical transmittance of greater than about 55%, greater than about 60%, greater than about 65%, or greater than about 70% for each of the blue, green, and red wavelength ranges.

Thus, for the substantially collimated incident light 34a incident at the first incident angle al and for each of the first and second polarization states, the optical film 30 may be substantially optically transmissive across each of the blue, green, and red wavelength ranges. In other words, for the substantially collimated incident light 34b incident at the first incident angle al and for each of the first and second polarization states, the optical film 30 may be substantially optically transmissive for the blue, green, red lights 23b, 10g, lOr.

Referring to FIGS. 1 and 3, in some embodiments, the optical diffuser 80 has a diffuse optical transmittance of greater than about 30% for each of the second, green, and red peak wavelengths 52b, 52g, 52r. In some embodiments, the optical diffuser 80 has the diffuse optical transmittance of greater than about 35%, greater than about 40%, greater than about 45%, greater than about 50%, greater than about 55%, or greater than about 60% for each of the second, green, and red peak wavelengths 52b, 52g, 52r.

Referring to FIGS. 2B and 3, in some embodiments, for the substantially normally incident light 35 and each of the second, green, and red peak wavelengths 52b, 52g, 52r, the plurality of polymeric microlayers 131, 132 reflects greater than about 60% of the incident light 35 having the first polarization state p and transmits greater than about 60% of the incident light 35 having the second polarization state s. In some embodiments, for the substantially normally incident light 35 and each of the second, green, and red peak wavelengths 52b, 52g, 52r, the plurality of polymeric microlayers 131, 132 reflects greater than about 70%, greater than about 80%, or greater than about 90% of the incident light 35 having the first polarization state p and transmits greater than about 70%, greater than about 80%, or greater than about 90% of the incident light 35 having the second polarization state s.

FIG. 4 illustrates a graph 450 depicting an optical reflectance of the back reflector 27 (shown in FIG. 1) versus wavelength, according to an embodiment of the present disclosure. Specifically, the graph 450 includes a curve 402 depicting the optical reflectance versus wavelength of the back reflector 27. More specifically, the curve 402 depicts the optical reflectance of the back reflector 27 for the substantially normally incident light 35 (shown in FIG. 2A).

Wavelength is expressed in nanometers (nm) in the abscissa. The optical reflectance is expressed as a reflectance percentage in the ordinate. Referring to FIGS. 1, 3, and 4, as is apparent from the curve 402, in some embodiments, the back reflector 27 has the average optical reflectance of greater than about 80% for each of the first, second, green, and red FWHMs 53v, 53b, 53g, 53r. In some embodiments, the back reflector 27 has the average optical reflectance of greater than about 85%, greater than about 90%, greater than about 95%, greater than about 98%, greater than about 99%, or greater than about 99.5% for each of the first, the second, green, and red FWHMs 53v, 53b, 53g, 53r. In the illustrated example of FIGS. 1 and 4, the back reflector 27 has an average optical reflectance of about 96.7 % for the first emitted FWHM 53v, an average optical reflectance of about 99.7 % for the second emitted FWHM 53b, an average optical reflectance of about 99.7 % for the green FWHM 53g, and an average optical reflectance of about 99.7 % for the red FHWM 53r.

Table 3 provided below summarizes the average optical reflectances of the back reflector 27 for the substantially normally incident light 35.

Table 3

where,

R27(0) refers to the average optical reflectance of the back reflector 27 for the substantially normally incident light 35 incident at an incident angle of 0 degree.

Referring to FIGS . 1 to 4, the one or more light converting films 15 may have a better efficiency in converting the emitted light 23 (i.e., having the emitted spectra 50v, 50b in the respective violet and blue wavelength ranges) to the green and red lights 10g, lOr than converting only the blue light in the blue wavelength range to the green and red lights 10g, lOr. Further, as discussed above, the one or more light converting films 15 may include quantum dots material. The quantum dots material may have a much higher absorption rate for the violet light 23v than the blue light 23b. Therefore, the amount of the quantum dots material required to convert the emitted light 23 including the violet light 23v may be substantially less than the amount of the quantum dots material required to convert only the blue light 23b in the blue wavelength range to the green and red lights 10g, lOr. This may reduce the cost of the one or more light converting films 15 of the backlight 200. Further, the optical film 30 disposed on the one or more light converting films 15 may reduce the violet light 23v that reaches the eyes of the viewer. Specifically, the optical film 30 may substantially block a portion of the violet light 23v which is not absorbed by the quantum dots material to reduce the violet light 23v that reaches the eyes of the viewer.

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.

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

1. A backlight for providing illumination to a display panel configured to display an image, 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, the emitted light comprising an emitted spectrum comprising first and second emitted peaks at respective first and second emitted peak wavelengths and respective non-overlapping first and second emitted full width at half maxima (FWHMs); one or more light converting films disposed on the extended emission surface of the extended illumination source and comprising green and red emission spectra comprising respective green and red peaks at corresponding green and red peak wavelengths and corresponding non-overlapping green and red FWHMs, the green FWHM disposed between the second and the red FWHMs, the one or more light converting films configured to receive the emitted light through the extended emission surface and convert at least portions of the received emitted light to green and red lights having respective green and red wavelengths disposed in the respective green and red FWHMs; and an optical film disposed on the one or more light converting films opposite the extended emission surface and comprising a plurality of polymeric layers numbering at least 10 in total, each of the polymeric layers having an average thickness of less than about 500 nm, such that for a substantially collimated incident light, a first incident angle of less than about 10 degrees, and for each of mutually orthogonal in-plane first and second polarization states, the plurality of polymeric layers has an average optical transmittance of less than about 10% for wavelengths across the first emitted FWHM, and an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs.

2. The backlight of claim 1 , wherein for a substantially collimated incident light, a second incident angle of no less than about 20 degrees, and for each of the first and second polarization states, the plurality of polymeric layers has an average optical transmittance of greater than about 20% for wavelengths across the first emitted FWHM, and an average optical transmittance of greater than about 60% and less than about 95% for each of the second, green, and red FWHMs.

3. The backlight of claim 1 , wherein for a substantially collimated incident light, a second incident angle of no less than about 30 degrees, and for each of the first and second polarization states, the plurality of polymeric layers has an average optical transmittance of greater than about 50% and less than about 95% for each of the first, second, green, and red FWHMs.

4. The backlight of claim 1, wherein for the substantially collimated incident light, the first incident angle, and for each of the first and second polarization states, the one or more light converting films have an average optical transmittance of greater than about 50% for the wavelengths across the second emitted FWHM.

5. The backlight of claim 1, wherein for the substantially collimated incident light, the first incident angle, and for each of the first and second polarization states, the one or more light converting films have an optical transmittance of greater than about 50% for the second emitted peak wavelength.

6. The backlight of claim 1, wherein for the substantially collimated incident light, the first incident angle, and for each of the first and second polarization states, the one or more light converting films have an average optical absorption of greater than about 20% for the wavelengths across the first emitted FWHM.

7. The backlight of claim 1 , wherein the emitted light from the one or more light sources comprises a first emitted light emitted from at least a first light source in the one or more light sources and a second emitted light emitted from at least a second light source in the one or more light sources, wherein: the first emitted light comprises a first emitted spectmm in the emitted spectrum comprising the first emitted peak at the first emitted peak wavelength with the corresponding first emitted FWHM; and the second emitted light comprises a second emitted spectrum in the emitted spectrum comprising the second emitted peak at the second emitted peak wavelength with the corresponding second emitted FWHM; wherein the first emitted light does not include any wavelengths from the second emitted FWHM and the second emitted light does not include any wavelengths from the first emitted FWHM.

8. The backlight of claim 1, wherein the first emitted peak wavelength is less than about 420 nm.

9. The backlight of claim 1, wherein the second emitted peak wavelength is greater than about 420 nm.

10. An optical construction for use in a backlight of a display system, the backlight configured to provide illumination to a display panel of the display system configured to display an image, the optical construction comprising: one or more light converting films; an optical film disposed on the one or more light converting films and comprising a plurality of polymeric layers numbering at least 10 in total, each of the polymeric layers having an average thickness of less than about 500 nm; and a bonding layer bonding the optical film to the one or more light converting films, such that for a substantially collimated incident light, a first incident angle of less than about 10 degrees, a second incident angle of no less than about 30 degrees, a violet wavelength range extending from about 390 nm to about 410 nm, a blue wavelength range extending from about 440 nm to about 460 nm, a green wavelength range extending from about 515 nm to about 540 nm, and a red wavelength range extending from about 600 nm to about 670 nm, and for each of mutually orthogonal in-plane first and second polarization states: the one or more light converting films convert at least portions of the substantially collimated incident light having wavelengths in the violet wavelength range to green and red lights having wavelengths in the respective green and red wavelength ranges, and have an optical transmittance of greater than about 50% for each of the blue, green and red wavelength ranges, and the plurality of polymeric layers has an average optical transmittance of less than about 10% for the violet wavelength range and the first incident angle, an average optical transmittance of greater than about 20% for the violet wavelength range and the second incident angle, and an average optical transmittance of greater than about 60% and less than about 95% for each of the blue, green, and red wavelength ranges and for each of the first and second incident angles.