Backlight and display system

Abstract

A backlight includes a plurality of light sources; a reflective polarizer disposed over the plurality of light sources; and an optical film disposed between the reflective polarizer and the plurality of discrete spaced apart light sources. For substantially collimated incident light, for a visible wavelength range, and for a first incident angle less than about 5 degrees, the reflective polarizer has an average optical reflectivity of at least 60% for p-polarized incident light and an average optical transmission of at least 60% for s-polarized incident light. For an average of p-polarized and s-polarized incident light and the visible wavelength range, the optical film has an average optical transmission T1 for the first incident angle and an average transmission T2 for a second incident angle greater than about 35 degrees, such that T1 / T2 ≥ 1.5.

Description

Technical Field

[0001] This disclosure relates in its entirety to a backlight source for providing illumination to a display panel, and a display system including a display panel disposed on the backlight source. Background Technology

[0002] Electronic devices such as smartphones, tablets, personal computers, and music players typically include displays. For example, electronic devices may incorporate liquid crystal display (LCD) panels. LCDs typically utilize the light modulation properties of liquid crystals. Liquid crystals do not emit light directly, and a backlight unit is used to illuminate the LCD panel, thereby producing images in color or monochrome. Therefore, the backlight unit provides illumination for the LCD panel. Summary of the Invention

[0003] In a first aspect, this disclosure provides a backlight source for providing illumination to a display panel. The backlight source includes a plurality of discrete, spaced-apart light sources arranged two-dimensionally on an optically reflective surface. The backlight source also includes a reflective polarizer disposed on the plurality of discrete, spaced-apart light sources. The backlight source further includes an optical film disposed between the reflective polarizer and the plurality of discrete, spaced-apart light sources, and extending substantially co-located with the reflective polarizer and the plurality of discrete, spaced-apart light sources in length and width. Each of the reflective polarizer and the optical film includes a plurality of polymer layers, totaling at least 10. Each of the plurality of polymer layers has an average thickness of less than about 500 nm. For substantially collimated incident light propagating in an incident plane, for a visible wavelength range extending from about 420 nanometers (nm) to about 680 nm, and for a first incident angle of less than about 5 degrees, the plurality of polymer layers of the reflective polarizer have an average optical reflectivity of at least 60% when the incident light is p-polarized and an average optical transmittance of at least 60% when the incident light is s-polarized. For substantially collimated incident light propagating in the incident plane, for the visible wavelength range, for the first incident angle, and for the average of p-polarized and s-polarized incident light, the multiple polymer layers of the optical film have an average optical transmittance T1. For substantially collimated incident light propagating in the incident plane, for the visible wavelength range, for the second incident angle greater than about 35 degrees, and for the average of p-polarized and s-polarized incident light, the multiple polymer layers of the optical film have an average optical transmittance T2, T1 / T2 ≥ 1.5.

[0004] In a second aspect, the present disclosure provides a display system including a display panel disposed on a backlight of the first aspect.

[0005] In a third aspect, this disclosure provides a display system. The display system includes a plurality of discrete, spaced-apart light sources arranged two-dimensionally on an optically reflective surface. The display system also includes a display panel disposed on the light sources and configured to form an image. The display system further includes a reflective polarizer disposed between the display panel and the light sources. The display system also includes an optical film disposed between the reflective polarizer and the light sources, and extending substantially co-located with the reflective polarizer and the light sources in length and width. Each of the reflective polarizer and the optical film includes a plurality of polymer layers, totaling at least 10. Each of the plurality of polymer layers has an average thickness of less than about 500 nm. The visible wavelength range extends from about 420 nm to about 680 nm. The infrared wavelength range extends from about 700 nm to about 780 nm. For substantially collimated incident light propagating in the plane of incidence, for a first incident angle of less than about 5 degrees and for the visible wavelength, the plurality of polymer layers of the reflective polarizer have an average optical reflectivity of at least 60% when the incident light is p-polarized and an average optical transmittance of at least 60% when the incident light is s-polarized. For substantially collimated incident light propagating in the incident plane, for a first incident angle and for the average of p-polarized and s-polarized incident light, the plurality of polymer layers of the optical film have optical transmittance T1a at at least one visible wavelength in the visible wavelength range and optical transmittance T1b at at least one infrared wavelength in the infrared wavelength range. For substantially collimated incident light propagating in the incident plane, for a second incident angle greater than about 35 degrees and for the average of p-polarized and s-polarized incident light, the plurality of polymer layers of the optical film have optical transmittance T1c at at least one visible wavelength and optical transmittance T1d at at least one infrared wavelength, where T1a / T1c ≥ 1.5 and T1b / T1d ≤ 0.7. Attached Figure Description

[0006] The exemplary embodiments disclosed herein can be more fully understood in light of the following detailed description taken in conjunction with the accompanying drawings. The drawings are not necessarily drawn to scale. Similar numbers used in the drawings refer to similar parts. However, it should be understood that the use of numbers to refer to parts in a given drawing is not intended to limit parts labeled with the same numbers in another drawing.

[0007] Figure 1 A schematic side view of a display system according to an embodiment of the present disclosure is shown;

[0008] Figure 2 A schematic top view of a backlight source according to an embodiment of the present disclosure is shown;

[0009] Figure 3 A schematic side view of a reflective polarizer according to an embodiment of the present disclosure is shown;

[0010] Figure 4 It is a graph depicting the optical transmittance versus wavelength of different polarization states of light incident on a reflective polarizer according to an embodiment of the present disclosure.

[0011] Figure 5 A schematic side view of an optical film according to an embodiment of the present disclosure is shown;

[0012] Figure 6 It is a graph depicting the optical transmittance versus wavelength of light incident on an optical film at different angles according to an embodiment of the present disclosure.

[0013] Figure 7A The list shows the corresponding Figure 6 A table showing the average optical transmittance of the optical film for different wavelength ranges and for light incident on the optical film at different angles.

[0014] Figure 7B A table is shown showing the values ​​of the ratio of the average optical transmittance of substantially perpendicularly incident light to the average optical transmittance corresponding to various angles of light incident on the optical film, according to embodiments of the present disclosure.

[0015] Figure 8A A schematic top view of a plurality of discrete, spaced-apart light sources disposed on an optical reflective surface according to an embodiment of the present disclosure is shown;

[0016] Figure 8B A schematic side view of a plurality of discrete, spaced-apart light sources and a circuit board according to an embodiment of the present disclosure is shown;

[0017] Figure 9 A graph illustrating the brightness versus polar angle of multiple light sources after transmission through the light conversion layer is shown according to an embodiment of the present disclosure.

[0018] Figure 10A A schematic side view of a light source, a first optical diffuser layer, and a light conversion component according to an embodiment of the present disclosure is shown;

[0019] Figure 10B A schematic side view of a light source, a first optical diffuser layer, and a light conversion component according to another embodiment of the present disclosure is shown;

[0020] Figure 11A A schematic side view of a first optical diffuser layer according to an embodiment of the present disclosure is shown;

[0021] Figure 11B A schematic side view of a first optical diffuser layer according to another embodiment of this disclosure is shown; and

[0022] Figure 12A schematic perspective view of a light redirection film according to an embodiment of the present disclosure is shown. Detailed Implementation

[0023] In the following description, reference is made to the accompanying drawings, which form a part thereof, and various embodiments are illustrated therein. It should be understood that other embodiments can be conceived and made without departing from the scope or spirit of this disclosure. Therefore, the following detailed description should not be considered limiting.

[0024] As used herein, the term "membrane" generally refers to a material having a very high length or width-to-thickness ratio. A membrane has two main surfaces defined by its length and width. Membranes typically exhibit good flexibility and can be used in a wide variety of applications, including displays. Membranes may also have a certain thickness or material composition, making them semi-rigid or rigid. The membranes described in this disclosure can be composed of a variety of polymeric materials. Membranes can be single-layered, multi-layered, or blends of different polymers.

[0025] As used herein, the term "optical film" generally refers to a film that can be used to produce optical effects. Optical films are generally at least partially transmissive, reflective, antireflective, polarized, visually clear, and / or diffuse for certain wavelengths of the electromagnetic spectrum (e.g., wavelengths in the visible, ultraviolet, or infrared regions of the electromagnetic spectrum).

[0026] As used herein, the term "layer" generally refers to the thickness of a material within a membrane that has a relatively uniform chemical composition. A layer can be any type of material, including polymers, cellulose, metals, or blends thereof. A given polymer layer may comprise a single polymer type or a blend of polymers and may include additives. A given layer may be combined with or bonded to other layers to form a membrane. A layer may be partially continuous or completely continuous compared to adjacent layers or membranes. A given layer may be partially or completely co-extended with adjacent layers. A layer may contain sublayers.

[0027] As used herein, the term "adhesive" generally refers to a polymer composition that can be used to adhere two adhesives together. Examples of adhesives may include curable adhesives, heat-activated adhesives, pressure-sensitive adhesives, or combinations thereof.

[0028] As used herein, the term "diffuser" generally refers to any film, layer, or substrate designed to scatter light. This light scattering can be influenced, for example, by using a textured surface on the substrate or by other means such as incorporating light-scattering particles into the film matrix. While it should be noted that all optical articles can be considered to scatter light to some extent, optically transparent or visually clear substrates and films are not considered "light scatterers" unless they are endowed with some light-scattering property.

[0029] As used herein, the term "specularly reflective" generally refers to the concept that can be described by referring to the term "specular reflection." "Specular reflection" or "specularly reflected" refers to the specular reflection of light, in which light from a single incident direction is reflected from a surface to a single outgoing direction, with both directions forming the same angle relative to the surface normal. "Specular reflectivity" is the fraction of the intensity of incident light that is specularly reflected by a surface, expressed as a percentage. Specular reflectivity can be a function of the wavelength of the incident light.

[0030] As used herein, the term "diffusely reflective" generally refers to the concept that can be described by the term "diffuse reflection." Diffuse reflection (or diffusely reflected) refers to the non-specular reflection of light, where light from a single incident direction is reflected from a surface to an outgoing direction excluding the specular direction. "Diffuse reflectivity" is the fraction of the intensity of incident light diffusely reflected by a surface, expressed as a percentage. Diffuse reflectivity can be a function of the wavelength of the incident light.

[0031] This disclosure relates in its entirety to a backlight source for providing illumination to a display panel, and a display system including a display panel disposed on the backlight source.

[0032] Backlights are used in electronic devices that include displays, such as computer monitors, televisions, mobile phones, personal digital assistants (PDAs), laptops, wearable devices, and other portable devices. Backlights can also be used with displays for automotive applications. In some cases, backlights can be integrated into the display system itself.

[0033] Current display systems typically include either direct-illuminated or edge-lit backlight units to illuminate the display panel. Edge-lit backlight units generally include a light source that emits light into the edge of a light guide device. The light guide device directs the light emitted from the light source and directs the emitted light towards the display panel. Direct-illuminated backlight units typically include an array of light sources that emit light perpendicularly toward the display panel. However, direct-illuminated backlight units are generally large and may produce uneven backlighting.

[0034] The backlight disclosed provides illumination to a display panel. The backlight includes a plurality of discrete, spaced-apart light sources arranged two-dimensionally on an optically reflective surface. The backlight also includes a reflective polarizer disposed on the plurality of discrete, spaced-apart light sources. The backlight also includes an optical film disposed between the reflective polarizer and the plurality of discrete, spaced-apart light sources, and extending substantially co-located with the reflective polarizer and the plurality of discrete, spaced-apart light sources in length and width. Each of the reflective polarizer and the optical film includes a plurality of polymer layers, totaling at least 10. Each of the plurality of polymer layers has an average thickness of less than about 500 nm. For substantially collimated incident light propagating in the plane of incidence, for a visible wavelength range extending from about 420 nanometers (nm) to about 680 nm, and for a first incident angle of less than about 5 degrees, the plurality of polymer layers of the reflective polarizer have an average optical reflectivity of at least 60% when the incident light is p-polarized and an average optical transmittance of at least 60% when the incident light is s-polarized. For substantially collimated incident light propagating in the incident plane, for the visible wavelength range, for the first incident angle, and for the average of p-polarized and s-polarized incident light, the multiple polymer layers of the optical film have an average optical transmittance T1. For substantially collimated incident light propagating in the incident plane, for the visible wavelength range, for the second incident angle greater than about 35 degrees, and for the average of p-polarized and s-polarized incident light, the multiple polymer layers of the optical film have an average optical transmittance T2, T1 / T2 ≥ 1.5.

[0035] Therefore, for the visible wavelength range, the average transmittance of the optical film for substantially collimated incident light (i.e., substantially perpendicular or coaxial light) propagating in the incident plane and incident at a first incident angle of less than about 5 degrees is greater than the average transmittance for substantially collimated incident light (i.e., off-axis light) propagating in the incident plane P and incident at a second incident angle of greater than about 35 degrees. Therefore, for the visible wavelength range, the optical film can have a greater reflectivity for substantially collimated incident light propagating in the incident plane and incident at the second incident angle. Therefore, for the visible wavelength range, the optical film can substantially reflect substantially collimated incident light propagating in the incident plane and incident at the second incident angle back to the optical reflective surface of the backlight source. The optical film can be used as a collimating multilayer optical film (CMOF), where the transmittance of coaxial light is greater than the transmittance of off-axis light.

[0036] Reflected light from the optical film can be recycled by the optical reflective surface of the backlight. The optical reflective surface can redirect the reflected light toward the optical film until the redirected light is incident substantially perpendicularly onto the optical film (i.e., incident along a direction closer to the coaxial direction of the backlight). Therefore, the optical film of the backlight of this disclosure can at least partially collimate and recycle off-axis light generated by a plurality of discretely spaced light sources or off-axis light redirected by the optical reflective surface between the optical film and the optical reflective surface of the backlight. Increased recycling can thus improve light utilization efficiency and increase the brightness of the illumination from the backlight. Furthermore, the recycling of off-axis light can further improve the uniformity of the backlight illumination. This can further contribute to reducing the thickness of the backlight, as it exhibits a good performance balance between brightness, uniformity, and light utilization efficiency compared to other backlights with similar thickness.

[0037] Figure 1 A schematic side view of a display system 400 according to an embodiment of the present disclosure is shown. Specifically, Figure 1 A cross-sectional side view of the display system 400 is shown. The display system 400 can be configured to display content such as text and / or graphics.

[0038] The display system 400 defines mutually orthogonal x-axis, y-axis, and z-axis. The x-axis and y-axis are in-plane axes of the display system 400, while the z-axis is a transverse axis set along the thickness of the display system 400. In other words, the x-axis and y-axis are set along the plane of the display system 400, while the z-axis is perpendicular to the plane of the display system 400.

[0039] In some embodiments, the display system 400 may be a touchscreen display incorporating a conductive capacitive touch sensor electrode layer or other touch sensor components (e.g., impedance touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.). In some other embodiments, the display system 400 may be a non-touch-sensitive display.

[0040] The display system 400 includes a backlight 300 and a display panel 10. The backlight 300 provides illumination to the display panel 10. The display system 400 includes a plurality of discrete, spaced-apart light sources 20 arranged two-dimensionally on an optical reflective surface 30. Specifically, the backlight 300 includes a plurality of discrete, spaced-apart light sources 20 arranged two-dimensionally on the optical reflective surface 30. In some embodiments, the plurality of discrete, spaced-apart light sources 20 are arranged substantially along the x-axis and y-axis. In some embodiments, the "pluralistic discrete, spaced-apart light sources 20" may be interchangeably referred to as "light sources 20".

[0041] In some embodiments, the display system 400 includes a display panel 10 disposed on a backlight 300. Specifically, the display system 400 includes a display panel 10 disposed on a light source 20 and configured to form an image 11. In some embodiments, the display panel 10 may selectively transmit or block light to form the image 11 for viewing by a user 14. In some embodiments, the display panel 10 includes a liquid crystal display (LCD) panel. In some embodiments, the display panel 10 may include a plurality of individually addressable pixels (not shown). In some embodiments, the display panel 10 may be a touch-sensitive display panel partially or entirely configured to receive touch input from the user 14. Therefore, the display system 400 may receive touch input from the user 14.

[0042] In some embodiments, the light source 20 may include one or more light emitters that emit light. In some embodiments, at least one of the plurality of discretely spaced light sources 20 includes a light-emitting diode (LED). In some other embodiments, at least one of the plurality of discretely spaced light sources 20 may include any other type of light emitter, such as a fluorescent lamp or any other suitable light-emitting device. In some embodiments, the light sources 20 may be uniformly controlled by the control circuitry (not shown) of the display system 400 or may be individually controlled.

[0043] In some embodiments, the light source 20 may emit light of any suitable color (e.g., blue, red, green, white, etc.). In some other embodiments, the light source 20 may be monochromatic or may include multiple light emitters operating at different wavelengths to produce white light output. In some embodiments, the plurality of discretely spaced light sources 20 includes one or more of a blue light emitting source, a green light emitting source, a red light emitting source, and a white light emitting source. In some embodiments, each of the plurality of discretely spaced light sources 20 is a blue light emitting source that emits only blue light. In some embodiments, the light source 20 may be encapsulated by any suitable encapsulant. In some embodiments, the encapsulant may be air. In some embodiments, the encapsulant may also include phosphorescent materials or other color-converting materials.

[0044] In some embodiments, the backlight 300 includes a circuit board 120 that includes an optical reflective surface 30. In some embodiments, LEDs may be mounted on the circuit board 120. Light from the light source 20 may be reflected from the optical reflective surface 30. Furthermore, the light reflected from the optical reflective surface 30 may illuminate the display panel 10. In some embodiments, the backlight 300 may include a side reflector 32 that surrounds at least a portion of the periphery of the backlight 300. The side reflector 32 may reflect light received at the edge portions of the backlight 300 from the optical reflective surface 30.

[0045] In some implementations, the optical reflective surface 30 is primarily specularly reflective for the visible wavelength range 80, extending from approximately 420 nanometers (nm) to approximately 680 nm. Figure 4 and Figure 6 At least one wavelength in the visible wavelength range 80 (shown) has a specular optical reflectivity greater than about 70%. In some embodiments, the optical reflective surface 30 has a specular optical reflectivity greater than about 80% for at least one wavelength in the visible wavelength range 80. In some embodiments, the optical reflective surface 30 is primarily diffuse reflective, having a diffuse optical reflectivity greater than about 70% for at least one wavelength in the visible wavelength range 80. In some embodiments, the optical reflective surface 30 has a diffuse optical reflectivity greater than about 80% for at least one wavelength in the visible wavelength range 80. In some embodiments, the optical reflective surface 30 may comprise a metallic surface. In some embodiments, the optical reflective surface 30 may contain one or more elements, such as silver, aluminum, a white coating, a non-conductive coating, etc. In some embodiments, the optical reflective surface 30 can be used to recycle light within the display system 400. For example, the optical reflective surface 30 can recycle light generated by the light source 20. This can result in improved light utilization efficiency and increased brightness.

[0046] The display system 400 also includes a reflective polarizer 40 disposed between the display panel 10 and the light source 20. Specifically, the backlight 300 includes reflective polarizers 40 disposed on a plurality of discretely spaced light sources 20. In some embodiments, the reflective polarizers 40 may substantially allow light of a specific polarization to pass through while substantially blocking light of orthogonal polarization.

[0047] Figure 2 A schematic top view of the backlight 300 is shown. The backlight 300 extends along the xy-plane, with its length L substantially along the y-axis and its width W substantially along the x-axis. Display system 400 ( Figure 1 (As shown) and various components of the backlight 300 can extend together along the length L and width W of the backlight 300.

[0048] Reference Figure 1 and Figure 2 The display system 400 also includes an optical film 50 disposed between the reflective polarizer 40 and the light source 20, and extending substantially together with the reflective polarizer and the light source in length L and width W. Specifically, the backlight 300 includes an optical film 50 disposed between the reflective polarizer 40 and a plurality of discretely spaced light sources 20, and extending substantially together with the reflective polarizer and the plurality of discretely spaced light sources in length L and width W. Reference will be made later. Figure 3 and Figure 5The reflective polarizer 40 and the optical film 50 are described in detail. Each of the reflective polarizer 40 and the optical film 50 comprises a plurality of polymer layers with a total count of at least 10. Figure 1 (Not shown in the image). In some embodiments, each of the reflective polarizer 40 and the optical film 50 includes a plurality of polymer layers with a total count of at least 50, at least 100, at least 200, at least 300, at least 400, or at least 500.

[0049] In some embodiments, the backlight 300 further includes a light conversion element 100 disposed between the optical film 50 and a plurality of discrete, spaced-apart light sources 20. In some embodiments, the light conversion element 100 is a light conversion film 100 that extends substantially co-located with the plurality of discrete, spaced-apart light sources 20 in length L and width W. In some embodiments, "light conversion element 100" is used interchangeably with "light conversion film 100" hereinafter. In some embodiments, a first adhesive layer 110 bonds the light conversion film 100 to the optical film 50. In some embodiments, the first adhesive layer 110 may include a visually clear adhesive layer or epoxy resin layer for bonding the light conversion film 100 to the optical film 50.

[0050] In some embodiments, the light conversion component 100 may be configured to convert light from the light source 20 from one color to different colors. In some embodiments, the light conversion component 100 is configured to convert at least a portion of blue light emitted by a blue light emitting source (e.g., one or more of the light sources in the light source 20) into green light and to convert at least a portion of blue light emitted by the blue light emitting source into red light. In some embodiments, the light conversion component 100 includes one or more of a phosphor, a fluorescent dye, and quantum dots. For example, when the light source 20 emits blue light, the phosphor in the light conversion component 100 (e.g., a phosphor material layer or other photoluminescent material) can convert at least a portion of the blue light into green light or at least a portion of the blue light into red light.

[0051] In some embodiments, the backlight 300 further includes a first optical diffuser layer 130 disposed between the optical film 50 and a plurality of discretely spaced light sources 20, and extending substantially together with the optical film and the plurality of discretely spaced light sources in length L and width W. In some embodiments, the first optical diffuser layer 130 is configured to scatter light. In some embodiments, the first optical diffuser layer 130 includes a plurality of discretely spaced optical diffuser portions 132 disposed on the first substrate 131. In some embodiments, the diffuser portions 132 are disposed between the first substrate 131 and the light sources 20. In some embodiments, the diffuser portions 132 and the light sources 20 are aligned with each other in a one-to-one correspondence. In some embodiments, the first optical diffuser layer 130 may diffuse light received from the light sources 20. Specifically, light emitted by the light sources 20 is received by the first optical diffuser layer 130 and scattered by the diffuser portions 132 of the first optical diffuser layer 130. Therefore, the first optical diffuser layer 130 can improve the uniformity of light emitted by multiple discretely spaced light sources 20.

[0052] In some embodiments, the light conversion component 100 and the first optical diffuser layer 130 are disposed between the optical film 50 and the light source 20. In some embodiments, a second adhesive layer 111 bonds the light conversion component 100 to the first optical diffuser layer 130. In some embodiments, the second adhesive layer 111 may comprise a visually clear adhesive layer or epoxy resin layer for bonding the light conversion component 100 to the first optical diffuser layer 130. In some embodiments, the second adhesive layer 111 is substantially similar to the first adhesive layer 110.

[0053] In some embodiments, the backlight 300 further includes an optical diffuser layer 140 disposed between the reflective polarizer 40 and the optical film 50. In some embodiments, the second optical diffuser layer 140 may be substantially similar to the first optical diffuser layer 130. In some embodiments, the backlight 300 further includes a third adhesive layer 112 for bonding the second optical diffuser layer 140 to the optical film 50. In some embodiments, the third adhesive layer 112 may include an optical adhesive layer or an epoxy resin layer for bonding the second optical diffuser layer 140 to the optical film 50. In some embodiments, the third adhesive layer 112 may be substantially similar to the first adhesive layer 110 and / or the second adhesive layer 111.

[0054] In some embodiments, the backlight 300 further includes at least one light redirection film 150, 151 disposed between the reflective polarizer 40 and the optical film 50. Figure 1In some exemplary embodiments, at least one light redirection film 150, 151 comprises two light redirection films 150, 151. In some embodiments, at least one light redirection film 150, 151 redirects at least one of the recirculated light and collimated light received from the optical film 50. In some embodiments, at least one of the at least one light redirection film 150, 151 (e.g., light redirection film 150) comprises a plurality of substantially parallel linear prisms 152 extending along a first direction and arranged along different second directions. In some embodiments, the first direction may be substantially along the y-axis and the second direction may be substantially along the x-axis. In some embodiments, at least one of the at least one light redirection film 150, 151 may enhance the brightness of an image (e.g., image 11) formed by the display panel 10. In some embodiments, the two light redirection films 150, 151 may be cross-prism films. Thus, the linear prisms 152 of the light redirection film 151 may be substantially orthogonal to the linear prisms (not shown) of the light redirection film 150.

[0055] In some embodiments, various components of the display system 400 and the backlight 300 are arranged along the z-axis. In some embodiments, the display system 400 may also include other light management layers. These layers can be used for spatial mixing or color mixing of light, light source shielding, and uniformity improvement. Layers that can be used for these purposes include, but are not limited to, diffuser films, diffuser plates, partially reflective layers, color mixing light guide devices or films, and non-Gaussian diffusers (diffuse systems in which light rays with peak brightness propagate in a direction not parallel to the direction of light rays with peak brightness in the input light). In some embodiments, these layers may include one or more color filter layers, polarizing layers, microstructured layers, or combinations thereof. In some embodiments, the display system 400 may also include a cover layer (not shown) disposed on the display panel 10. The cover layer can provide protection for the various layers of the display system 400.

[0056] Figure 3 A schematic side view of a reflective polarizer 40 according to an embodiment of the present disclosure is shown. In some embodiments, the reflective polarizer 40 is an advanced polarizing filter (APF). However, the reflective polarizer 40 can be any suitable reflective polarizer. In some embodiments, the reflective polarizer 40 may include one or more of a multilayer polymer reflective polarizer, a wire grating reflective polarizer, and a diffuse reflective polarizer. In some embodiments, light reflected from the reflective polarizer 40 may be emitted by an optical reflective surface 30 (…). Figure 1 (As shown) Recycle.

[0057] The reflective polarizer 40 includes a plurality of polymer layers 60, 61 with a total count of at least 10. In some embodiments, the reflective polarizer 40 includes a plurality of polymer layers 60, 61 with a total count of at least 50, at least 100, at least 200, at least 300, at least 400, or at least 500. Figure 3 In the illustrated embodiment, the reflective polarizer 40 includes a plurality of polymer layers 60, 61 arranged in an alternating configuration. Specifically, the polymer layers 60, 61 are formed as alternating polymer layers along the z-axis. Each of the polymer layers 60, 61 has an average thickness of less than about 500 nm. In some embodiments, each of the polymer layers 60, 61 has an average thickness of less than about 400 nm, less than about 300 nm, or less than about 200 nm. The average thickness is measured along the z-axis.

[0058] In some embodiments, one of the polymer layers 60, 61 comprises a material with a high refractive index relative to the other. In some embodiments, at least one of the polymer layers 60, 61 comprises a birefringent material. In some embodiments, the reflective polarizer 40 may further include at least one intermediate layer (not shown) disposed between the plurality of polymer layers 60, 61. In some embodiments, the intermediate layer may comprise a material with a low refractive index.

[0059] In some embodiments, the reflective polarizer 40 further includes at least one skin 63 disposed on its plurality of polymer layers 60, 61. Figure 3 In an exemplary embodiment, the reflective polarizer 40 includes a skin 63 located on two main surfaces of the reflective polarizer 40. Specifically, a plurality of polymer layers 60, 61 are disposed between the skins 63. At least one skin 63 protects the plurality of polymer layers 60, 61 and also provides mechanical stability to the reflective polarizer 40. In some cases, at least one skin 63 may act as a protective boundary layer (PBL). In some embodiments, at least one skin 63 has an average thickness greater than about 500 nm. In some embodiments, at least one skin 63 has an average thickness greater than about 750 nm or greater than about 1000 nm.

[0060] like Figure 3 As shown, the substantially collimated incident light 70 propagating in the incident plane P travels at a normal N relative to the main surface 41. R The first incident angle α1 is incident on the principal surface 41 of the reflecting polarizer 40. The incident plane P can substantially correspond to the xz plane. Normal N RIt can be located in the incident plane P. In some embodiments, the first incident angle α1 is less than about 5 degrees. In some embodiments, the first incident angle α1 is less than about 4 degrees, less than about 3 degrees, less than about 2 degrees, or less than about 1 degree. However, the incident light 70 can be incident on the reflective polarizer 40 at any tilt angle. In some embodiments,

[0061] "The essentially collimated incident light 70" can be interchangeably referred to as "incident light 70".

[0062] Figure 4 It is a reflective polarizer 40 that describes different polarization states of incident light. Figure 3 An exemplary graph 90 shows the optical transmittance versus wavelength. Wavelength is expressed in nanometers (nm) on the horizontal axis. Wavelengths include the visible wavelength range 80 and the infrared wavelength range 81 extending from about 700 nm to about 780 nm. Optical transmittance is expressed as a percentage of transmittance on the left vertical axis. Reflectance is expressed as a percentage of reflectance on the right vertical axis. The percentage of reflectance is complementary to the percentage of transmittance, i.e., percentage of reflectance = (100 - percentage of transmittance).

[0063] Graph 90 includes curves 172 and 174. Curve 172 depicts the optical transmittance versus the wavelength of the reflecting polarizer 40 when the incident light 70 is p-polarized. Curve 174 depicts the optical transmittance versus the wavelength of the reflecting polarizer 40 when the incident light 70 is s-polarized.

[0064] Reference Figure 3 and Figure 4 As is evident from curve 172, for substantially collimated incident light 70 propagating in the plane of incidence P, for the visible wavelength range 80, and for a first incident angle α1 less than about 5 degrees, when the incident light 70 is p-polarized, the plurality of polymer layers 60, 61 of the reflective polarizer 40 have an average optical reflectivity R of at least 60%. avg In some embodiments, for substantially collimated incident light 70 propagating in the incident plane P, for the visible wavelength range 80, and for a first incident angle α1 of less than about 5 degrees, when the incident light 70 is p-polarized, the plurality of polymer layers 60, 61 of the reflective polarizer 40 have an average optical reflectivity R of at least 70%, at least 80%, at least 90%, or at least 95%. avg .

[0065] As is evident from curve 174, for substantially collimated incident light 70 propagating in the incident plane P, for the visible wavelength range 80, and for a first incident angle α1 less than about 5 degrees, when the incident light 70 is s-polarized, the plurality of polymer layers 60, 61 of the reflective polarizer 40 have an average optical transmittance T of at least 60%. avgIn some embodiments, for substantially collimated incident light 70 propagating in the incident plane P, for the visible wavelength range 80, and for a first incident angle α1 of less than about 5 degrees, when the incident light 70 is s-polarized, the plurality of polymer layers 60, 61 of the reflective polarizer 40 have an average optical transmittance T of at least 70%, at least 80%, at least 90%, or at least 95%. avg .

[0066] Figure 5 A schematic side view of an optical film 50 is shown. The optical film 50 includes a plurality of polymer layers 64, 65 with a total count of at least 10. In some embodiments, the optical film 50 includes a plurality of polymer layers 64, 65 with a total count of at least 50, at least 100, at least 200, at least 300, at least 400, or at least 500. Figure 5 In the illustrated embodiment, the optical film 50 includes a plurality of polymer layers 64, 65 arranged in an alternating configuration. Specifically, the polymer layers 64, 65 are formed as alternating polymer layers along the z-axis. Each of the polymer layers 64, 65 has an average thickness of less than about 500 nm. In some embodiments, each of the polymer layers 64, 65 has an average thickness of less than about 400 nm, less than about 300 nm, or less than about 200 nm.

[0067] In some embodiments, one of the polymer layers 64, 65 comprises a material with a high refractive index relative to the other. In some embodiments, at least one of the polymer layers 64, 65 comprises a birefringent material. In some embodiments, the optical film 50 may further comprise at least one intermediate layer (not shown) disposed between the plurality of polymer layers 64, 65. In some embodiments, the intermediate layer may comprise a material with a low refractive index.

[0068] In some embodiments, the optical film 50 further includes at least one skin 66 disposed on its plurality of polymer layers 64, 65. Figure 5 In an exemplary embodiment, the optical film 50 includes skins 66 located on two main surfaces of the optical film 50. Specifically, a plurality of polymer layers 64, 65 are disposed between the skins 66. At least one skin 66 protects the plurality of polymer layers 64, 65 and also provides mechanical stability to the optical film 50. In some cases, at least one skin 66 may be PBL (polymer-polymer-blended). In some embodiments, at least one skin 66 has an average thickness greater than about 500 nm. In some embodiments, at least one skin 66 has an average thickness greater than about 750 nm or greater than about 1000 nm.

[0069] like Figure 5 As shown, incident light 70 propagating in the incident plane P can be relative to the normal N of the main surface 51 of the optical film 50.O The light is incident on the optical film 50 at a first incident angle α1 less than approximately 5 degrees and a second incident angle α2 greater than approximately 35 degrees. The incident plane P can substantially correspond to the xz plane. Normal N O It can be located in the incident plane P. In some embodiments, the first incident angle α1 is less than about 4 degrees, less than about 3 degrees, less than about 2 degrees, or less than about 1 degree. In some embodiments, the second incident angle α2 is greater than about 40 degrees, greater than about 45 degrees, greater than about 50 degrees, or greater than about 55 degrees. In some embodiments, the incident light 70 propagating in the incident plane P is relative to the normal N of the main surface 51 of the optical film 50. O The incident light 70 is incident on the optical film 50 at a third incident angle α3 between approximately 20 degrees and approximately 40 degrees. In some embodiments, the third incident angle α3 is between approximately 25 degrees and approximately 35 degrees. In some embodiments, the incident light 70 propagating in the incident plane P is relative to the normal N of the main surface 51 of the optical film 50. O The light is incident on the optical film 50 at a fourth incident angle α4 greater than about 45 degrees. In some embodiments, the fourth incident angle α4 is greater than about 50 degrees or less than about 55 degrees.

[0070] Figure 6 It depicts optical films 50 corresponding to different incident angles. Figure 5 An exemplary curve of optical transmittance versus wavelength is shown in Figure 91. Wavelength is expressed in nanometers (nm) on the horizontal axis. Wavelengths include the visible wavelength range 80 and the infrared wavelength range 81. Optical transmittance is expressed as a percentage of transmittance on the left vertical axis.

[0071] Curve graph 91 includes curves 182, 184, 186, 188, and 190. (See reference...) Figure 5 and Figure 6 Curve 182 depicts the normal N relative to the main surface 51 of the optical film 50. O The optical transmittance of the optical film 50 as a function of wavelength, assuming light incident at 0 degrees and the average values ​​for p-polarized and s-polarized incident light (i.e., light linearly polarized in and perpendicular to the plane of incidence, respectively). Curve 184 depicts the optical transmittance of the optical film 50 with respect to the normal N relative to the main surface 51 of the optical film 50. O The optical transmittance of the optical film 50 as a function of wavelength, assuming light incident at 30 degrees and the average values ​​for p-polarized and s-polarized incident light. Curve 186 depicts the optical transmittance relative to the normal N of the main surface 51 of the optical film 50. O The optical transmittance of the optical film 50 as a function of wavelength, assuming light incident at 40 degrees and the average values ​​for p-polarized and s-polarized incident light. Curve 188 depicts the optical transmittance relative to the normal N of the main surface 51 of the optical film 50. OThe optical transmittance of the optical film 50 as a function of wavelength, assuming light incident at 50 degrees and the average values ​​for p-polarized and s-polarized incident light. Curve 190 depicts the optical transmittance relative to the normal N of the main surface 51 of the optical film 50. O The optical transmittance of the optical film 50 with wavelength, given light incident at 60 degrees and the average values ​​for p-polarized and s-polarized incident light.

[0072] Figure 7A and Figure 7B Tables 200 and 250 are shown respectively. Table 200 lists the corresponding... Figure 6 The curve shown in graph 91 is the incident light on optical film 50 ( Figure 1 and Figure 5 Table 200 provides exemplary values ​​for the average optical transmittance for the visible wavelength range 80 and for the infrared wavelength range 81 at different angles of light incident on the optical film 50. Table 200 includes multiple column headers in row 202. The column headers in row 202 include different angles of light incident on the optical film 50. Column 203 indicates the visible wavelength range 80 (approximately 420 nm to approximately 680 nm) and the infrared wavelength range 81 (approximately 700 nm to approximately 780 nm). Table 200 also includes multiple cells corresponding to the different values ​​of the average optical transmittance for the visible wavelength range 80 and for the infrared wavelength range 81 at different angles of light incident on the optical film 50.

[0073] Table 200 includes cells 204 and 206, which indicate the values ​​of average optical transmittance T1 and average optical transmittance T3 corresponding to the visible wavelength range 80 (approximately 420 nm to approximately 680 nm) and the infrared wavelength range 81 (approximately 700 nm to approximately 780 nm), respectively, and are for substantially perpendicular incident light (incident angle less than approximately 5 degrees). Furthermore, Table 200 includes indications for the infrared wavelength range 81 and for the infrared wavelength range 81 relative to the normal N. O Cell 208 shows the value of the average optical transmittance T4 of light incident at 30 degrees, indicating the wavelength range of 80 nm for visible wavelengths and the wavelength relative to the normal N. O Cell 210 shows the value of the average optical transmittance T2 of light incident at 40 degrees, indicating the infrared wavelength range 81 and the value relative to the normal N. O Cell 212 shows the value of the average optical transmittance T5 of light incident at 50 degrees.

[0074] Table 250 lists exemplary values ​​for the ratio of the average optical transmittance of substantially perpendicularly incident light (incident angle less than about 5 degrees) to the average optical transmittance corresponding to various angles of light incident on the optical film 50. Table 250 includes several column headers in row 252. The column headers in row 252 include the visible wavelength range 80 (about 420 nm to about 680 nm) and the infrared wavelength range 81 (about 700 nm to about 780 nm). Column 254 indicates the ratio of the average optical transmittance of substantially perpendicularly incident light (incident angle less than about 5 degrees) for both the visible wavelength range 80 and the infrared wavelength range 81 to the average optical transmittance corresponding to various angles of light incident on the optical film 50. Table 250 also includes several cells corresponding to different values ​​of the ratio of the average optical transmittance of substantially perpendicularly incident light to the average optical transmittance corresponding to various angles of light incident on the optical film 50 for both the visible wavelength range 80 and the infrared wavelength range 81.

[0075] Table 250 includes cell 256, which indicates the ratio of average optical transmittance T1 to average optical transmittance T2 in the visible wavelength range 80; cell 258, which indicates the ratio of average optical transmittance T3 to average optical transmittance T4 in the infrared wavelength range 81; and cell 260, which indicates the ratio of average optical transmittance T3 to average optical transmittance T5 in the infrared wavelength range 81.

[0076] Now refer to Figures 5 to 7B And curve 182, for substantially collimated incident light 70 propagating in the incident plane P, for a first incident angle α1 (approximately 0 degrees), and for the average value of p-polarized and s-polarized incident light, the plurality of polymer layers 64, 65 of the optical film 50 have an optical transmittance T1a at at least one visible wavelength 82 within the visible wavelength range 80, and an optical transmittance T1b at at least one infrared wavelength 83 within the infrared wavelength range 81. Furthermore, for substantially collimated incident light 70 propagating in the incident plane P, for the visible wavelength range 80, for the first incident angle α1, and for the average value of p-polarized and s-polarized incident light, the plurality of polymer layers 64, 65 of the optical film 50 have an average optical transmittance T1. Furthermore, for the average value of p-polarized and s-polarized incident light propagating in the incident plane P, and for the infrared wavelength range 81, the plurality of polymer layers 64, 65 of the optical film 50 have an average optical transmittance T3 with respect to the first incident angle α1.

[0077] Referring to curves 184 and 186, for the average values ​​of p-polarized and s-polarized incident light propagating in the incident plane P, and for the infrared wavelength range 81, the multiple polymer layers 64 and 65 of the optical film 50 have an average optical transmittance T4 between approximately 20 degrees and approximately 40 degrees or between approximately 25 degrees and approximately 35 degrees for the third incident angle α3.

[0078] Furthermore, referring to curve 188, for substantially collimated incident light 70 propagating in the incident plane P, for a second incident angle α2 greater than approximately 35 degrees, and for the average value of p-polarized and s-polarized incident light, the plurality of polymer layers 64, 65 of the optical film 50 have an optical transmittance T1c at at least one visible wavelength 82 in the infrared wavelength range 81 and an optical transmittance T1d at at least one infrared wavelength 83. Furthermore, for substantially collimated incident light 70 propagating in the incident plane P, for the visible wavelength range 80, for a second incident angle α2 greater than approximately 35 degrees, and for the average value of p-polarized and s-polarized incident light, the plurality of polymer layers 64, 65 of the optical film 50 have an average optical transmittance T2.

[0079] Referring to curves 188 and 190, for the average values ​​of p-polarized and s-polarized incident light propagating in the incident plane P and for the infrared wavelength range 81, the multiple polymer layers 64 and 65 of the optical film 50 have an average optical transmittance T5 greater than about 45 degrees, greater than about 50 degrees, or greater than about 55 degrees for the fourth incident angle α4.

[0080] As is evident from graph 91, the optical transmittance T1a is more than 1.5 times the optical transmittance T1c, i.e., T1a / T1c ≥ 1.5. In some embodiments, T1a / T1c ≥ 1.8, T1a / T1c ≥ 2, T1a / T1c ≥ 2.5, T1a / T1c ≥ 3, T1a / T1c ≥ 3.5, T1a / T1c ≥ 4, T1a / T1c ≥ 4.5, or T1a / T1c ≥ 5. Furthermore, the optical transmittance T1b is less than or equal to 0.7 times the optical transmittance T1d, i.e., T1b / T1d ≤ 0.7. In some embodiments, T1b / T1d ≤ 0.6 or T1b / T1d ≤ 0.5.

[0081] Furthermore, as is evident from graph 91 and tables 200 and 250, the average optical transmittance T1 is greater than or equal to 1.5 times the average optical transmittance T2, i.e., T1 / T2 ≥ 1.5. In some embodiments, T1 / T2 ≥ 1.8, T1 / T2 ≥ 2, T1 / T2 ≥ 2.5, T1 / T2 ≥ 3, T1 / T2 ≥ 3.5, T1 / T2 ≥ 4, T1 / T2 ≥ 4.5, or T1 / T2 ≥ 5. Additionally, the average optical transmittance T3 is greater than or equal to the average optical transmittance T4, i.e., T3 / T4 ≥ 1. In some embodiments, T3 / T4 ≥ 1.1, T3 / T4 ≥ 1.2, or T3 / T4 ≥ 1.3. Furthermore, the average optical transmittance T3 is less than or equal to 0.7 times the average optical transmittance T5, i.e., T3 / T5 ≤ 0.7. In some implementations, T3 / T5 ≤ 0.6 or T3 / T5 ≤ 0.5.

[0082] Now refer to Figure 1 , Figures 5 to 7B For the visible wavelength range 80, the optical film 50 therefore has an average transmittance T1 for substantially collimated incident light 70 (i.e., substantially perpendicular or coaxial light) propagating in the incident plane P and incident at a first incident angle α1 of less than about 5 degrees. Furthermore, for the visible wavelength range 80, the optical film 50 has an average transmittance T2 for substantially collimated incident light 70 (i.e., off-axis light) propagating in the incident plane P and incident at a second incident angle α2 of greater than about 35 degrees. The average transmittance T1 is greater than the average transmittance T2. Therefore, for the visible wavelength range 80, the optical film 50 can have a greater reflectivity for substantially collimated incident light 70 propagating in the incident plane P and incident at the second incident angle α2. Therefore, for the visible wavelength range 80, the optical film 50 can substantially reflect the substantially collimated incident light 70 propagating in the incident plane P and incident at the second incident angle α2 back to the optical reflective surface 30 of the backlight 300. The optical film 50 can be used as a collimating multilayer optical film (CMOF), in which the transmittance of coaxial light is greater than that of off-axis light.

[0083] Reflected light from the optical film 50 can be recycled by the optical reflective surface 30 of the backlight 300. The optical reflective surface 30 can redirect the reflected light toward the optical film 50 until the redirected light is incident substantially perpendicularly onto the optical film 50 (i.e., incident along a direction closer to the coaxial direction of the backlight 300). Therefore, the optical film 50 of the backlight 300 can at least partially collimate and recycle off-axis light generated by a plurality of discretely spaced light sources 20 or off-axis light redirected by the optical reflective surface 30 between the optical film 50 and the optical reflective surface 30 of the backlight 300. Increased recycling can thus improve light utilization efficiency and increase the brightness of the illumination from the backlight 300. Furthermore, the recycling of off-axis light can further improve the uniformity of the backlight illumination. This can further contribute to reducing the thickness of the backlight 300, as the backlight 300 exhibits a good performance balance between brightness, uniformity, and light utilization efficiency compared to other backlights with similar thickness.

[0084] Furthermore, for the infrared wavelength range 81, the optical film 50 has an average transmittance T3 for substantially collimated incident light 70 propagating in the incident plane P and incident at a first incident angle α1 of less than about 5 degrees. For the infrared wavelength range 81, the optical film 50 has an average transmittance T4 for substantially collimated incident light 70 propagating in the incident plane P and incident at a third incident angle α3 between about 20 degrees and about 40 degrees. For the infrared wavelength range 81, the optical film 50 has an average transmittance T5 for substantially collimated incident light 70 propagating in the incident plane P and incident at a fourth incident angle α4 greater than about 45 degrees. The average transmittance T3 is greater than the average transmittance T4. However, the average transmittance T5 is greater than the average transmittance T3. Therefore, the average transmittance of the optical film 50 in the infrared wavelength range 81 can be reduced from substantially perpendicular incidence (e.g., the first incident angle α1) to incident angles between about 20 degrees and about 40 degrees (e.g., the third incident angle α3). However, the average transmittance of the optical film 50 in the infrared wavelength range 81 can increase with an incident angle of 45 degrees or greater (e.g., a fourth incident angle α4). Therefore, the average transmittance of the optical film 50 in the infrared range 81 can be increased or decreased over a variety of incident angles.

[0085] Figure 8A A schematic top view is shown of a plurality of discrete, spaced-apart light sources 20 disposed on an optical reflective surface 30. Figure 8A In the exemplary embodiments, the light sources 20 are arranged in a regular two-dimensional array, forming rows 21 and columns 22 of the light sources 20. In some embodiments, the sources may be arranged in a hexagonal array or other irregular pattern. Typically, each of the plurality of light sources 20 may include a single LED, a pair of LEDs, 2 to 10 LEDs, or any number of LEDs. Figure 8A In the exemplary implementation, a single LED representing each light source 20 is shown. Furthermore, the light source 20 is shown as having a substantially circular shape. However, the light source 20 can have any suitable shape, such as a square, rectangle, ellipse, polygon, etc. In some implementations, the light sources 20 may have the same or different dimensions based on desired application properties.

[0086] In some embodiments, each light source 20 may be covered by an encapsulant of a different shape or with different dopants. In some embodiments, the encapsulant may include a color-converting material, such as a phosphorescent material or quantum dots. In some embodiments, some of the plurality of discretely spaced light sources 20 may have different characteristics to tune the light emitted from the light source 20. In some embodiments, some of the plurality of discretely spaced light sources 20 may emit red light, blue light, green light, or white light.

[0087] In some implementations, circuit board 120 ( Figure 1 (As shown) may include an optical reflective surface 30. The light source 20 may be mounted on the circuit board 120 by any suitable attachment mechanism (e.g., soldering) and may be arranged using any suitable arrangement based on the desired application properties.

[0088] Figure 8B A schematic side view of the light source 20 and the circuit board 120 is shown. In some embodiments, light emitted by multiple light sources 20 and incident on the optical film 50 has a minimum brightness L1 within an emission cone 24 centered on the optical axis B substantially orthogonal to the optical reflective surface 30. Figure 9 The values ​​shown are L1 (minimum) and L2 (maximum). Figure 9 (where L is the maximum value), wherein the half-cone angle CA is at least 40 degrees. In some embodiments, the half-cone angle CA is at least 45 degrees, at least 50 degrees, at least 55 degrees, or at least 60 degrees.

[0089] Figure 9 An exemplary graph 92 is shown, including curve 162, which depicts the transmission of multiple light sources 20 through diffuser 130. Figure 1 (as shown) and color conversion film 100 ( Figure 1 The brightness and polar angle after (as shown). This result was obtained on a partial optical stack to measure the backlight 300 ( Figure 1 As shown) entering the optical film 50 ( Figure 1 (As shown) Illumination uniformity before. Polar angle is expressed in degrees on the horizontal axis. Luminance is expressed in cd / m² on the left vertical axis. 2 The polar angle can correspond to the observer's viewing angle or the emitted light cone 24 ( ). Figure 8B The semi-cone angle CA is shown in the figure.

[0090] As is evident from curve 162, for polar angles substantially in the range of approximately -40 degrees to approximately 40 degrees, the luminance is substantially constant. For a half-cone angle CA of at least ±40 degrees, the luminance varies between a minimum luminance L1 and a maximum luminance L2. The minimum luminance L1 is greater than or equal to 0.5 times the maximum luminance L2, i.e., L1 / L2 ≥ 0.5. In some embodiments, L1 / L2 ≥ 0.55, L1 / L2 ≥ 0.6, L1 / L2 ≥ 0.65, L1 / L2 ≥ 0.7, or L1 / L2 ≥ 0.75.

[0091] Figure 10A A schematic side view of the light source 20, the first optical diffuser layer 130, and the light conversion component 100a is shown. The light conversion component 100a substantially encapsulates a plurality of discretely spaced light sources 20. In some embodiments, the light conversion component 100a may have a... Figure 1The light conversion component 100a has substantially similar optical properties. In some embodiments, the light conversion component 100a may be substantially conformal to the light source 20 disposed on the optical reflective surface 30 of the circuit board 120. In some embodiments, the light conversion component 100a may have any thickness based on the desired application properties.

[0092] Figure 10B A schematic side view of the light source 20, the first optical diffuser layer 130, and the light conversion component 100b is shown. In some embodiments, the light conversion component 100b may have a... Figure 1 The light conversion component 100b has substantially similar optical properties. The light conversion component 100b includes a plurality of discrete light conversion component portions 101. Each light conversion component portion 101 substantially encapsulates a corresponding light source in the light source 20. Therefore, each light conversion component portion 101 can be associated with a corresponding light source in the light source 20. In some embodiments, the plurality of discrete light conversion component portions 101 can have any thickness based on desired application properties.

[0093] Figure 11A and Figure 11B A schematic side view of a first optical diffuser layer 130 according to different embodiments of the present disclosure is shown. The first optical diffuser layer 130 includes a plurality of discrete, spaced-apart optical diffuser portions 132 disposed on a first substrate 131. (Refer to...) Figure 11A At least one of the diffuser portions 132 is primarily a volume diffuser 133. Typically, in a volume diffuser, small particles or spheres with different refractive indices are embedded in the main material of the volume diffuser. The embedded particles or spheres act as light scattering elements. In some other embodiments, the refractive index of the material of the volume diffuser 133 varies throughout the body of the volume diffuser 133, thus causing light passing through the material to be refracted or scattered at different points.

[0094] Reference Figure 11B At least one of the diffuser portions 132 is primarily a surface diffuser 132a. Typically, a surface diffuser utilizes surface roughness to refract or scatter light in multiple directions. The rough surface of the surface diffuser 132a may be exposed to air or the surrounding medium and may result in maximum angular spread of the incident light. In some embodiments, at least two diffuser portions 132 are primarily surface diffusers 132a, 132b and include two distinct surface structures. It should be understood that, as Figure 11B The shape and construction of the surface diffusers 132a and 132b shown are exemplary and can be varied according to desired application properties.

[0095] Figure 12A schematic perspective view of light redirection films 150 and 151 is shown. In some embodiments, at least one light redirection film 150 or 151 includes a first prism film 150a and a second prism film 151a. In some embodiments, the first prism film 150a includes a plurality of substantially parallel linear first prisms 152a extending along a first direction and arranged along a different second direction. The second prism film 151a includes a plurality of substantially parallel linear second prisms 153a extending along a third direction different from the first direction and arranged along a different fourth direction. In some embodiments, the first and fourth directions may be substantially aligned along the y-axis. In some embodiments, the second and third directions may be substantially aligned along the x-axis. Thus, the first prism film 150a and the second prism film 151a may be cross-constructed (i.e., the second prism film 151a may be rotated 90 degrees relative to the first prism film 150a). In other words, the first prisms 152a and the second prisms 153a are arranged perpendicular to each other.

[0096] In some embodiments, the first prism film 150a and the second prism film 151a can enhance the brightness of an image (e.g., image 11) emitted by the display system 400 by at least partially collimating and recycling the light emitted by the light source 20. The first prism 152a and the second prism 153a can redirect off-axis light in a direction closer to the coaxial direction of the display system 400.

[0097] Example

[0098] An exemplary film for the reflective polarizer 40 and the optical film 50 is prepared according to the embodiments of this specification.

[0099] The reflective polarizer 40 is fabricated as follows. A single multilayer optical group is co-extruded. This group comprises alternating layers of the following materials: 90 / 10coPEN, a polymer consisting of 90% polyethylene naphthalate (PEN) and 10% polyethylene terephthalate (PET), and a low-refractive-index isotropic layer made of a blend of polycarbonate and copolyester (PC:coPET). The low-refractive-index isotropic layer has a refractive index of approximately 1.57 and retains a substantially isotropic uniaxial orientation. The molar ratio of PC:coPET is approximately 42.5 mol% polycarbonate (PC) and 57.5 mol% coPET, and the material has a glass transition temperature (Tg) of 105 °C. This isotropic material is chosen such that, after stretching, the refractive index of the isotropic material in the two non-stretched directions substantially matches the refractive index of the birefringent material in the non-stretched directions, while in the stretched direction, the refractive indices between the birefringent and non-birefringent layers are substantially mismatched.

[0100] 90 / 10PEN and PC:coPET polymers are fed from a separate extruder into a multilayer co-extrusion feed block, where these polymers are assembled into a group having 275 alternating optical layers, with a thicker PC:coPET polymer protecting the boundary layer on each side, resulting in a total of 277 layers. Following the feed block, a top layer is added, wherein the polymer used for the top layer is a second PC:coPET with a molar ratio of 50 mol% polycarbonate and 50 mol% coPET, and a Tg of 110°C. The multilayer melt is then cast through a die onto a cooling roll in a conventional manner for polyester films, where it is quenched. The cast sheet is then stretched in a parabolic tenter as described in U.S. Patent No. 7,104,776 (Merrill et al.) at a temperature and draw ratio (approximately 6.0) similar to that described in Example 2A of U.S. Patent Application Publication No. 2007 / 0047080 (Stover et al.).

[0101] In the production of multilayer films, the goal of linear layer distribution in individual groups is to optimally balance optical performance and production efficiency. The target slope is approximately 0.24 nm / layer. As measured by a capacitance meter, the film has a final thickness of approximately 26.5 micrometers.

[0102] Optical film 50 is prepared as follows. Optical film 50 is prepared using the feed block method described in U.S. Patent Application 61 / 332,401 (Attorney General's File No. 64248US002), filed May 7, 2010, entitled "Feedblock for Manufacturing Multilayer Polymeric Films". Two packages of 275 layers, each having alternating low-refractive-index and high-refractive-index polymer layers, are co-extruded as casting sheets and subsequently stretched in a tenter frame on a continuous film production line. The high-refractive-index material is 90 / 10coPEN (90% naphthalene ester units and 10% terephthalate units). The low-refractive-index isotropic layer is made of a blend of polycarbonate and copolyester (PC:coPET). The low-refractive-index layer has a refractive index of approximately 1.57 and retains a substantially isotropic uniaxial orientation. The PC:coPET molar ratio is approximately 42.5 mol% of polycarbonate and 57.5 mol% of coPET, and the material has a Tg of 105°C.

[0103] The 325 alternating microlayers in each group are arranged in a sequence of 1 / 4 wavelength layer pairs to produce Figure 6 The transmission spectrum is shown. The overall thickness of the film is approximately 76 micrometers.

[0104] Unless otherwise stated, all figures used in the specification and claims to indicate feature dimensions, quantities, and physical properties should be understood to be modified by the term "about". Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations and can vary according to the desired properties sought by those skilled in the art using the teachings disclosed herein.

[0105] While specific embodiments have been illustrated and described herein, those skilled in the art will recognize that various alternative and / or equivalent embodiments may be used in place of the illustrated and described embodiments without departing from the scope of this disclosure. This application is intended to cover any modifications or variations of the specific embodiments discussed herein. Therefore, this disclosure is intended to be limited only by the claims and their equivalents.

Claims

1. A backlight source for providing illumination to a display panel, the backlight source comprising: Multiple discrete, spaced-apart light sources are arranged two-dimensionally on an optical reflective surface; A reflective polarizer, wherein the reflective polarizer is disposed on the plurality of discrete, spaced-apart light sources; and An optical film is disposed between the reflective polarizer and the plurality of discrete, spaced-apart light sources, and extends substantially in the same length and width as the reflective polarizer and the plurality of discrete, spaced-apart light sources. Each of the reflective polarizer and the optical film comprises a plurality of polymer layers, totaling at least 10, each of the plurality of polymer layers having an average thickness of less than 500 nm. This ensures that for substantially collimated incident light propagating in the plane of incidence, and for the visible wavelength range extending from 420 nm to 680 nm: For a first incident angle of less than 5 degrees, the plurality of polymer layers of the reflective polarizer have an average optical reflectivity of at least 60% when the incident light is p-polarized and an average optical transmittance of at least 60% when the incident light is s-polarized; With respect to the first incident angle and the average optical transmittance for p-polarized incident light and s-polarized incident light, the plurality of polymer layers of the optical film have an average optical transmittance T1; and For a second incident angle greater than 35 degrees and for the average optical transmittance of p-polarized and s-polarized incident light, the plurality of polymer layers of the optical film have an average optical transmittance T2, T1 / T2 ≥ 1.

5. The average optical transmittance of p-polarized and s-polarized incident light propagating in the incident plane, and the plurality of polymer layers of the optical film for the infrared wavelength range extending from 700 nm to 780 nm, are as follows: For the first incident angle, the average optical transmittance is T3; For a third incident angle between 20 degrees and 40 degrees, the average optical transmittance is T4; and For a fourth incident angle greater than 45 degrees, the average optical transmittance is T5, T3 / T4≥1, and T3 / T5≤0.

7.

2. The backlight source according to claim 1, wherein each of the plurality of discretely spaced light sources is a blue light emitting light source that emits only blue light, and wherein the backlight source further comprises a light conversion component disposed between the optical film and the plurality of discretely spaced light sources and configured to convert at least a portion of the blue light emitted by the blue light emitting light source into green light and to convert at least a portion of the blue light emitted by the blue light emitting light source into red light.

3. The backlight source according to claim 1 further includes a light conversion component and a first optical diffuser layer disposed between the optical film and the light source, wherein a second adhesive layer bonds the light conversion component to the first optical diffuser layer.

4. The backlight source according to claim 1 further includes a second optical diffuser layer, wherein the second optical diffuser layer is disposed between the reflective polarizer and the optical film.

5. The backlight source according to claim 1, further comprising at least one light redirection film disposed between the reflective polarizer and the optical film, the at least one light redirection film redirecting at least one of the recirculated light and collimated light received from the optical film.

6. The backlight source according to claim 5, wherein at least one of the at least one light redirection films comprises a plurality of substantially parallel linear prisms extending along a first direction and arranged along different second directions.

7. The backlight according to claim 5, wherein the at least one light redirection film comprises a first prism film and a second prism film, the first prism film comprising a plurality of substantially parallel linear first prisms extending along a first direction and arranged along different second directions, and the second prism film comprising a plurality of substantially parallel linear second prisms extending along a third direction different from the first direction and arranged along different fourth directions.

8. The backlight source according to claim 1, wherein the light emitted by the plurality of light sources and incident on the optical film has a minimum brightness L1 and a maximum brightness L2 in an emission cone centered on an optical axis substantially orthogonal to the optical reflective surface, wherein the half-cone angle is at least 40 degrees and L1 / L2 ≥ 0.

5.

9. A display system, comprising: Multiple discrete, spaced-apart light sources are arranged two-dimensionally on an optical reflective surface; A display panel is disposed on the light source and configured to form an image; A reflective polarizer is disposed between the display panel and the light source; and An optical film is disposed between the reflective polarizer and the light source, and extends substantially co-located with the reflective polarizer and the light source in both length and width. Each of the reflective polarizer and the optical film comprises a plurality of polymer layers, totaling at least 10, each of the plurality of polymer layers having an average thickness of less than 500 nm. This extends the visible wavelength range from 420 nm to 680 nm and the infrared wavelength range from 700 nm to 780 nm for substantially collimated incident light propagating in the plane of incidence. For a first incident angle of less than 5 degrees and the visible wavelength range, the plurality of polymer layers of the reflective polarizer have an average optical reflectivity of at least 60% when the incident light is p-polarized and an average optical transmittance of at least 60% when the incident light is s-polarized; With respect to the first incident angle and the average optical transmittance for p-polarized incident light and s-polarized incident light, the plurality of polymer layers of the optical film have an optical transmittance T1a at at least one visible wavelength in the visible wavelength range and an optical transmittance T1b at at least one infrared wavelength in the infrared wavelength range. For a second incident angle greater than 35 degrees and for the average optical transmittance of p-polarized incident light and s-polarized incident light, the plurality of polymer layers of the optical film have an optical transmittance T1c at at least one visible wavelength and an optical transmittance T1d at at least one infrared wavelength, T1a / T1c ≥ 1.5, T1b / T1d ≤ 0.7.

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