WO2017214122A1

WO2017214122A1 - Devices comprising a patterned color conversion medium and methods for making the same

Info

Publication number: WO2017214122A1
Application number: PCT/US2017/036123
Authority: WO
Inventors: John Phillip Ertel; Timothy James Orsley; William Richard Trutna
Original assignee: Corning Incorporated
Priority date: 2016-06-08
Filing date: 2017-06-06
Publication date: 2017-12-14
Also published as: JP2019523990A; CN109564919A; KR20190006204A; TW201802552A

Abstract

Disclosed herein are optical assemblies comprising a light emitting device, a color conversion medium at least partially circumscribing the light emitting device, and a transparent lens positioned in overlying registration with the light emitting device and the color conversion medium. Also disclosed herein are color conversion assemblies comprising a color conversion medium arranged in a ring-shaped pattern between two substrates. Further disclosed herein are light conversion devices comprising a substrate having a first surface patterned with a color conversion medium and a reflective layer disposed on the first surface and at least partially encapsulating the color conversion medium. Display, lighting, and electronic devices comprising such assemblies and devices are also disclosed herein.

Description

DEVICES COMPRISING A PATTERNED COLOR CONVERSION MEDIUM AND METHODS FOR MAKING THE SAME

[0001] This application claims the benefit of priority under 35 U.S.C. § 1 19 of U.S. Provisional Application Serial No. 62/347,351 filed on June 8, 2016, the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

[0002] The disclosure relates generally to devices comprising a patterned color conversion medium, and more particularly to optical assemblies comprising at least two of a lens, a color conversion medium, and/or a light source, as well as display and illumination devices comprising such assemblies.

BACKGROUND

[0003] Liquid crystal displays (LCDs) are commonly used in various electronics, such as cell phones, laptops, electronic tablets, televisions, and computer monitors. Conventional LCDs typically comprise a blue light emitting diode (LED) and color converting elements, such as a phosphors or quantum dots (QDs). LEDs may also be used in combination with color converting elements in lighting applications, such as luminaires. For example, blue light from an LED can be directed through a color conversion medium which may convert some of the light to green and/or red light as it passes through. The combination of blue, green, and red light is perceived by the human eye as white light.

[0004] Color converting elements, such as phosphors and QDs, are not 100% quantum efficient in converting light and some of the light energy may be absorbed by the color converting element as heat. Additionally, the color conversion process itself may generate heat, e.g., due to Stokes shift when shorter wavelengths are converted to longer wavelengths. In some instances, up to 20-40% of the absorbed light is converted to heat. Because excess heat may degrade the color converting element, it can be important to establish adequate cooling or heat sink pathways to dissipate the l generated heat and maintain the color converting element within a desired operating temperature. While phosphor materials may be able to operate at moderate

temperatures (e.g. , up to about 300°C), QD materials are highly temperature sensitive and may experience degradation at temperatures of greater than about 100°C.

[0005] Due to the temperature sensitivity of QDs, traditional backlight units (BLUs) are generally configured to avoid close proximity and/or direct contact between the QDs and the LEDs. Such a configuration may be referred to as a "remote" configuration. For instance, as shown in the LCD assembly of FIG. 1 , QDs are often supplied in the form of a glass or polymeric tube, capillary, sheet, or film, e.g., a QD enhancement film (QDEF) 1 , which can be placed over (but not in direct physical contact with) an array of LEDs 2 arranged on a printed circuit board (PCB) 3. Light 4 emitted from the LEDs 2 can thus pass through the QDs as it travels to the liquid crystal (LC) panel 5. The BLU 6 can further comprise a heat sink 7 attached to the PCB, which may dissipate heat generated by the LEDs 2.

[0006] However, these assemblies may not provide sufficient cooling because heat from the QDs is dissipated mainly by free or forced convective air forces 8 passing through the gap between the LEDs and QDEF. The QDEF itself is a relatively poor thermal conductor and does not benefit from direct thermal contact with the heat sink 7. As such, the LCD assembly may be operated at a lower light intensity and/or power to protect the QDs from thermal degradation, which may undesirably result in an overall reduction in display or lighting brightness. Additionally, such assemblies can result in significant material waste because the QDs are uniformly dispersed over the entire LED array, rather than discretely positioned only over each individual LED in the array.

[0007] Accordingly, it would be advantageous to provide devices comprising a patterned color conversion medium that can reduce material waste, thereby lowering the cost of such devices. It would also be advantageous to provide devices that include heat sink pathways or other cooling mechanisms that can dissipate heat produced by the color conversion medium.

SUMMARY

[0008] The disclosure relates, in various embodiments, to optical assemblies comprising a light emitting device disposed on a first surface of a substrate, a ring structure comprising a color conversion medium disposed on the first surface of the substrate, and a transparent lens positioned in overlying registration with the light emitting device and the ring structure, wherein the color conversion medium is spaced apart from and at least partially circumscribes the light emitting device. Display, lighting, and electronic devices comprises such assemblies or assembly arrays are also disclosed herein.

[0009] The disclosure additionally relates to color conversion assemblies comprising a sub-assembly comprising a first substrate and a second substrate sealed together to form at least one cavity comprising a color conversion medium, and a transparent lens positioned in overlying registration with the sub-assembly, wherein the at least one cavity comprises a continuous ring-shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern, and wherein the transparent lens comprises a convex surface and at least a portion of the convex surface comprises an equiangular spiral curvature. Optical assemblies comprising the color conversion assembly and at least one light emitting device are further disclosed herein, as well as display, lighting, and electronic devices comprises such assemblies.

[0010] Also disclosed herein are color conversion assemblies comprising a transparent substrate and a reflective substrate sealed together to form at least one cavity comprising a color conversion medium, wherein the at least one cavity comprises a continuous ring-shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern. Optical assemblies comprising the color conversion assembly and at least one light emitting device and/or transparent lens are additionally disclosed herein, as well as display, lighting, and electronic devices comprises such assemblies.

[0011] Further disclosed herein are light conversion devices comprising a transparent substrate having a first surface and an opposing light emitting surface, a color conversion medium disposed on the first surface, and a reflective layer disposed on the first surface and encapsulating at least a portion of the color conversion medium. Light guide assemblies comprising the light conversion device optically coupled to a light emitting device are also disclosed herein. Still further disclosed herein are methods for making a color conversion assembly, the methods comprising patterning a color conversion medium on a first surface of a transparent substrate and depositing a protective layer on the first surface to encapsulate at least a portion of the color conversion medium, wherein one of the substrate or the protective layer comprises a reflective material.

[0012] Additional features and advantages of the disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the methods as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0013] It is to be understood that both the foregoing general description and the following detailed description present various embodiments of the disclosure, and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure and, together with the description, serve to explain the principles and operations of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following detailed description can be further understood when read in conjunction with the following drawings in which, where possible, like numerals are used to refer to like elements, and:

[0015] FIG. 1 illustrates an exemplary LCD assembly;

[0016] FIGS. 2A-C illustrate cross-sectional views of lenses according to various embodiments of the disclosure;

[0017] FIG. 3A is a schematic illustrating total internal reflection (TIR) within a lens according to additional embodiments of the disclosure;

[0018] FIG. 3B illustrates a topographical surface map of an exemplary lens formed by rotation of the curve of FIG. 3A around its axis of rotation;

[0019] FIG. 4 illustrates a coordinate system used to construct a rotationally symmetric lens according to various embodiments of the disclosure;

[0020] FIG. 5 illustrates a constant incidence angle curve according to further embodiments of the disclosure; [0021] FIG. 6 illustrates a perspective view of a linear lens according to certain embodiments of the disclosure;

[0022] FIG. 7 illustrates an array of lenses according to additional embodiments of the disclosure;

[0023] FIG. 8 illustrates an optical assembly according to various embodiments of the disclosure;

[0024] FIG. 9 illustrates an array of optical assemblies according to further embodiments of the disclosure;

[0025] FIGS. 10-12 illustrate optical assemblies according to alternative embodiments of the disclosure;

[0026] FIGS. 13A-B illustrate plan and cross-sectional views of a patterned color conversion assembly;

[0027] FIG. 14 illustrates an exemplary display device comprising a BLU assembly according to non-limiting embodiments of the disclosure;

[0028] FIGS. 15A-C illustrate exemplary light guide plates (LGPs) comprising a patterned color conversion medium; and

[0029] FIGS. 16A-C illustrate exemplary light conversion devices comprising a patterned color conversion medium and a reflective layer.

DETAILED DESCRIPTION

[0030] Various embodiments of the disclosure will now be discussed with reference to FIGS. 2-16, which illustrate exemplary embodiments of lenses, light emitting devices, light conversion devices, and optical assemblies comprising such devices. Display and lighting devices comprising these devices and assemblies are also disclosed herein. The following general description is intended to provide an overview of the claimed devices, and various aspects will be more specifically discussed throughout the disclosure with reference to the non-limiting depicted embodiments, these embodiments being interchangeable with one another within the context of the disclosure. Lenses

[0031] Disclosed herein are lenses comprising a contact surface, a convex surface, and a central region disposed therebetween, wherein the convex surface comprises a negative axiconic depression extending into the central region. The negative axiconic depression can, for example, comprise a hollow conical region having a cone half-angle ranging from about 15° to about 40°. Also disclosed herein are lenses comprising a contact surface, a convex surface, and a central region disposed therebetween, where at least a portion of the convex surface comprises an equiangular spiral curvature. In certain embodiments, the lenses may be linear or rotationally symmetric. Suitable materials from which the lens may be constructed include optically transparent materials, such as glasses and plastics.

[0032] FIG. 2A illustrates a cross-sectional view of an exemplary lens 100 according to embodiments of the disclosure. The lens 100 can comprise a contact surface 101 , a convex surface 102, and a central region 103 disposed therebetween. The convex surface 102 can comprise a negative axiconic depression 104, e.g., at or near its apex, and this depression 104 can extend into the central region 103. In some embodiments, the negative axiconic depression 104 can have a vertex 107 that points towards the contact surface 101. In further embodiments, discussed in more detail below, the convex surface 102 can be truncated such that it does not fully extend to meet the contact surface 101. In such embodiments, a truncated surface 105

(optionally coated with a reflective layer) may connect the contact surface 101 and convex surface 102. Furthermore, the contact surface 101 can, in non-limiting embodiments, comprise one or more recesses or cut-outs 106, which can optionally be provided to house a light source in an optical assembly, also discussed in more detail below.

[0033] As used herein, the term "convex" is intended to denote a surface shape defining a lens that is thinner at its outer edges than at its center, e.g., when the contact surface is planar. In some embodiments, the convex second surface may be

envisioned as a surface that curves out or extends outward from a centerline of a planar first surface of the lens, e.g., a semi-spherical or semi-ellipsoidal shape. The convex surface of the lens can be envisioned as a rounded dome, the dimensions of which need not be perfectly rounded, semi-spherical, or semi-ellipsoidal.

[0034] As depicted in FIG. 2B, a "convex" surface may be rotationally symmetric around a vertical center line 108 of the lens 100. For instance, as illustrated, the convex surface 102 may comprise a rotationally symmetric hemisphere, e.g., as in a typical lens. However, other shapes such as elliptical, parabolic, or 2D surfaces generated by revolving a 1 D profile function around the center line are also possible and intended to fall within the scope of the disclosure. A 1 D profile function may be generated by splines and/or may not be continuous in slope. A convex surface that is rotational symmetric around the center line of the lens can also be described by a standard aspheric sag equation, or the Forbes polynomial aspheric sag equation. The sag of the surface that these equations describe is the normal distance from a plane normal to the center line at the surface intersection with that normal line. The sag of a convex surface largely increases in magnitude with distance from the centerline and has a sign that makes the lens thinner at the edge of the lens than the center of the lens. In some radial zones, the lens may become thicker with radial distance from the lens, but is largely thinner at the edge.

[0035] It is to be understood that the term "convex" is not limited to surfaces that are rotationally symmetric around the vertical centerline. It is possible that an

asymmetric surface shape would be beneficial to provide different illumination profiles. The equations that describe this shape might not be standard sag equations, but may describe a free-form surface shape used in the field of optical fabrication. It is also to be understood that the term "convex" is not limited to surfaces that are continuous. The surface may also be a compound surface for which the sag of different spatial regions is defined by different equations.

[0036] FIG. 2C provides a detailed view of region C in FIG. 2A, which includes the negative axiconic depression 104. As used herein, the term "negative axiconic depression" is intended to denote a hollow conical region capable of diverging

collimated light, which may be envisioned as an indent or depression into the convex surface of the lens substantially in the shape of a cone. According to various

embodiments, the vertical centerline 109 of the cone can be spatially oriented to align or substantially align with, or to be parallel or substantially parallel to, the vertical centerline of the convex surface (see 108 in FIG. 2B). The term "negative" is used to indicate that the conical surface forms a lens shape that diverges collimated light incident on the cone, as opposed to a positive axiconic lens that converges said light to form an axial line focus in space. Just as a spherical surface in optical systems can be designed to be slightly aspherical in shape to improve performance, the shape of the cone can also be deviated from a perfect cone to improve performance and/or to simplify manufacture.

[0037] For example, in certain instances, it can be difficult to fabricate a negative axiconic depression 104 having a perfectly sharp point or vertex 107. Thus, in some embodiments, the depression 104 may have a vertex 107 with a blunt or rounded curvature, e.g., as depicted in FIG. 2C. Thus, instead of having a "width" defined by a single point (as in the case of a perfect cone), the rounded vertex 107 may have a width w that is greater than 0. However, it is noted that a blunt or rounded vertex 107 may allow some light to pass through at shallow angles, e.g., resulting in undesirable light leakage in this region. While the vertex 107 may be machined or molded to increase its sharpness, in some embodiments, it may also be possible to alter one or more surfaces of the negative axiconic depression to counteract this effect. For instance, a reflective film (not illustrated) may be deposited on at least a portion of the rounded vertex of the cone such that light may be reflected backward and can possibly traverse a different path and reflect such that it escapes the lens at a different point. At least a portion of the rounded vertex 107 may also be blocked by coatings or solid objects, such as small balls or spheres affixed or forced into the apex of the cone.

[0038] According to various embodiments, the negative axiconic depression 104 may have a cone half-angle β ranging from about 15° to about 40°, such as from about 20° to about 35°, or from about 25° to about 30°, including all ranges and subranges therebetween. As used herein, the term "cone half-angle" and variations thereof is intended to denote the angle formed by the vertical centerline 109 of the cone with a line 110 transecting an outermost point x of the cone and the vertical centerline of the cone. As noted above, the depression 104 need not be perfectly conical and the sides may not be perfectly linear. For instance, as shown in FIG. 2C, the sides of the cone may curve inward toward the vertical centerline of the cone or, in other embodiments, may bow outward (not illustrated).

[0039] It should be noted that, while the lens 100 is depicted in FIGS. 2A-C as plano-convex, e.g., having a contact surface 101 that is substantially planar, it is also possible for the first surface to be non-planar. A slightly convex contact surface (e.g., having a radius of curvature greater than about 100 mm) may, in some instance, provide improved optical properties, such as decreased refraction in the "backwards" (e.g., away from the user) direction. However, for practical purposes, such as ease of construction, a plano-convex lens may be more easily implemented into an optical assembly. In some embodiments, the contact surface can be planar or substantially planar. Furthermore, while FIG. 2B illustrates a contact surface 101 having a spherical shape that is rotationally symmetric around the vertical centerline 108 of the lens, it is to be understood that the contact surface 101 may be rotationally asymmetric around the vertical centerline of the lens, may be aspherical, and/or may have a free-form shape. As previously noted, the contact surface 101 may be provided with one or more recesses or cut-outs 106 intended to accommodate optical components such as light sources, color conversion medium, circuits, etc.

[0040] The overall height (or thickness) and/or diameter of the lens 100 may be dependent, e.g., on the dimensions of the optical assembly in which it is intended to be used. For instance, the diameter of the lens may be chosen to be larger than a dimension (e.g., diameter, length, and/or width) of a light source to which it may be optically coupled. Solely for illustrative purposes, the overall lens height (or thickness) may range, in non-limiting embodiments, from about 0.1 mm to about 20 mm, from about 0.2 mm to about 15 mm, from about 0.5 to about 10 mm, from about 1 mm to about 8 mm, from about 2 mm to about 7 mm, from about 3 mm to about 6 mm, or from about 4 mm to about 5 mm, including all ranges and subranges therebetween.

Similarly, a diameter of the lens can range, for example, from about 1 mm to about 100 mm, from about 5 mm to about 90 mm, from about 10 mm to about 80 mm, from about 20 mm to about 70 mm, from about 30 mm to about 60 mm, or from about 40 mm to about 50 mm, including all ranges and subranges therebetween. [0041] The size and/or shape of the lens may also depend upon a desired optical pathway for light emitted by a light source optically coupled to the lens. For example, with reference to FIG. 3A, the curvature of a convex lens surface 102 can be designed such that light 110 emitted from a light source (e.g., LED) 111 optically coupled to the lens strikes the convex surface 102 at an angle greater than the critical angle and become "trapped" within the lens due to total internal reflection (TIR). As used herein, the term "optically coupled" is intended to denote that a light source is positioned relative to the lens so as to introduce or inject light into the lens. A light source may be optically coupled to a component such as a lens, light guide plate (LGP), or other substrate even though it is not in physical contact with the component.

[0042] Total internal reflection (TIR) is the phenomenon by which light

propagating in a first material (e.g., glass, plastic, etc.) comprising a first refractive index can be totally reflected at the interface with a second material (e.g., air, etc.) comprising a second refractive index lower than the first refractive index. TIR can be explained using Snell's law:

n_x sin(£? ) = n₂ sin($_r)

which describes the refraction of light at an interface between two materials of differing indices of refraction. In accordance with Snell's law, ni is the refractive index of a first material, n₂ is the refractive index of a second material, 0, is the angle of the light incident at the interface relative to a normal to the interface (incident angle), and Θ_Γ is the angle of refraction of the refracted light relative to the normal. When the angle of refraction (Θ_Γ) is 90°, e.g., sin(0_r) = 1 , Snell's law can be expressed as:

^ ^ sin ¹^)

The incident angle 0, under these conditions may also be referred to as the critical angle 0_C. Light having an incident angle greater than the critical angle (0, > 0_C) will be totally internally reflected within the first material, whereas light with an incident angle equal to or less than the critical angle (0, < 0_C) will be transmitted by the first material.

[0043] In the case of an exemplary interface between air (n_?=1 ) and glass

(n₂=1 .5), the critical angle (0_C) can be calculated as 41⁰ Thus, if light propagating in the glass strikes the air-glass interface at an incident angle greater than 41 °, all the incident light will be reflected from the interface at an angle equal to the incident angle. If the reflected light encounters a second interface comprising an identical refractive index relationship as the first interface, the light incident on the second interface will again be reflected at a reflection angle equal to the incident angle.

[0044] Accordingly, the lenses disclosed herein may be configured to "trap" light, e.g., such that light injected into the lens by the light source can repeatedly propagate within the lens, reflecting along the convex surface 102 or alternately between the contact surface 101 and convex surface 102 unless or until there is a change to the interfacial conditions. In some embodiments, referring to FIG. 3A, the curvature of the convex surface 102 may be engineered such that substantially all light 110 emitted from the light source 111 , regardless of the point of origin on the light source itself, strikes the convex surface at incidence angle Θ,, where Θ, > 0_C. For example, light 110 emitted from the upper corners (upper right corner 113 illustrated in FIG. 3A) of the light source 111 may have the smallest incident angle with respect to the convex surface 102 of the lens and, thus, the lens may be configured such that even light emitted from this position on the light source 111 has an incident angle Θ, greater than the critical angle

[0045] With reference to FIG. 3A, color conversion medium 112 can be distributed around a perimeter of the light source 111 to provide regions of altered interfacial conditions, e.g., such that reflected light incident upon the color conversion medium 112 is scattered forward at an angle less than the critical angle 0_C. As such, TIR may be "broken" or interrupted in regions where the color conversion medium 112 is distributed, such that light 110 can escape the lens as transmitted light 110'. Such an arrangement may also have the added benefit of providing a heat sink pathway for the color conversion medium itself (e.g., via the PCB below the color conversion medium (not shown)), such that an optical assembly employing the disclosed configuration can operate at elevated temperatures. Moreover, because light 110 from the light source 111 reflects and/or spreads out spatially before passing through the color conversion medium 112, the color conversion medium may be exposed to a reduced light flux density, e.g., meaning the optical assembly can be operated at a higher light intensity as compared to prior art configurations. These and other potential benefits are discussed in more detail below with reference to the disclosed optical assemblies.

[0046] It is noted that only the right half of the convex lens surface curvature is illustrated in FIG. 3A (as well as the corresponding half of the LED 111 and color conversion medium 112). Rotation of the curve around the vertical centerline 108 of the lens (in this case also an axis of symmetry) will generate a convex lens surface 102 having the topography illustrated in FIG. 3B. Moreover, as illustrated in FIG. 2, the convex surface 102 in FIG. 3A is truncated such that it does not fully extend to meet the contact surface 101. The truncated surface (not labeled) can, in certain embodiments, be coated with a reflective layer 114 to prevent the escape of light from this region.

[0047] According to non-limiting embodiments, the lens may be configured such that substantially all light emitted from the light source strikes the convex surface 102 at a constant incident angle Θ,, where Θ, = k > 0_C. Referring again to FIG. 3A, a constant incidence angle curve r(0) of the convex surface 102 can be constructed by defining a coordinate system with the origin defined as the upper right corner 113 of the light source (as shown), or upper left corner (not shown). As depicted in FIG. 4, a tangent vector t to curve r(0) can be drawn using equation (1 ):

where e is the unit vector representing the direction of a light ray, and h is a unit vector orthogonal to e. The dot product of t and e can be expressed by equation (2):

where a is the angle formed between t and e. Because the incident angle is the complement of a, equation (2) can be rewritten as the following equation (3):

Equation (3) can be further simplified to provide a differential equation (4) in polar coordinates:

dr

— = r tan 0 (4) The solution to equation (4) is represented by equation (5):

r(6») = _r(O)e^0tan0i (5)

where r(0) is the starting point or origin of curve r(0) at Θ = 0.

[0048] FIG. 5 depicts an exemplary constant incidence angle curvature for a convex lens surface 102, in which r(0) = 0.4 mm and 0j = 42° A range of angles Θ (0 < Θ < TT) for light emitted from light source 111 are illustrated, each resulting in an incident angle Θ, = 42° with the convex surface of the lens. It is noted that for angles Θ > π, the constant incidence angle curve will define a spiral, also called a logarithmic spiral, equiangular spiral, or growth spiral. As such, a convex surface 102 having a constant incidence angle curvature may comprise at least one region having an equiangular spiral curvature. In some embodiments, substantially all of the convex surface may have an equiangular spiral curvature. In other embodiments, a portion of the convex surface may have an equiangular spiral curvature (e.g., in the case of a lens with a truncated surface).

[0049] It is further noted that light rays tend to travel along the top of the lens, which may leave a gap 115 proximate the light source 111. As such, light emanating from the optical assembly may be perceived as a ring of light forming a perimeter around the light source 111 , although some light may also leak out in a central region corresponding to the negative axiconic depression, as noted above. The lens apex can be machined, molded, or otherwise modified (e.g., with a reflective layer) to reduce or eliminate such light leakage, if desired.

[0050] The peak in curve r(0) for (0 < Θ < TT) can be expressed as angle Θ_ρ = Θ, + TT/2. The Cartesian coordinates for this peak can be represented by equations (6a-b):

The boundary or maximum limit 116 of the convex surface to the right of the y-axis occurs at angle Θ,. As such, the Cartesian coordinates for this rightmost point can be expressed by equations (7a-b):

x_r = r(O)e^0itan0icos0j (7a)

y_r = r(O)e^0itan0isin0j (7b) The value of x_r can be used to determine the maximum radius of a light source that can be optically coupled to the lens.

[0051] While FIGS. 2-3 illustrate a rotationally symmetric (e.g., hemispherical) lens 100, configured to optically couple with a single light source, it is noted that other configurations may be employed in which a lens may be coupled to more than one light source. For instance, as depicted in FIG. 6, a linear lens 100' can have a contact surface 101' a convex surface 102' similar to those defined above for a symmetrical lens 100. Moreover, in some embodiments, the convex surface 102' of the linear lens 100' can similarly be engineered to have a constant incidence angle curvature

(equiangular spiral curvature). Moreover, the lens 100' can have a double-lobed configuration (Α'-Β') as illustrated or a single-lobed configuration (A' or B'). In some embodiments, during construction of an optical assembly, separate lobes A' and B' may be mated together to form a double-lobed configuration. The double-lobed (Α'-Β') linear lens can be arranged in overlying registration with a light source array 111', or each separate lobe (Α', Β') can each be positioned in overlying registration with one side of the light source array 111'.

[0052] The linear lens 100' depicted in FIG. 6 can be formed using any method known in the art, such as extrusion, molding, casting, or stamping, to name a few.

Similar manufacturing processes can be used to create a rotationally symmetric lens 100 or an array of such lenses. Such an exemplary array is depicted in FIG. 7, in which each individual lens 100 may comprise an aperture or recess 106 corresponding to each individual light source (not shown) in an accompanying LED array.

Optical Assemblies

[0053] Also disclosed herein are optical assemblies comprising at least one lens as described above in combination with at least one of a light emitting device and/or color conversion medium. The lens may be optically coupled to at least one light source, such as an LED. The optical assembly may also comprise a lens and a color conversion medium comprising at least one color converting element, such as phosphors, quantum dots, and/or lumiphores, e.g., fluorophores, and or light emitting polymers. Non-limiting exemplary optical assemblies may include backlight units (BLUs), light guide plates (LGPs), color conversion devices, light emitting devices, light conversion devices, or luminaires, to name a few.

[0054] In various embodiments, the optical assemblies comprise a light emitting device disposed on a first surface of a substrate, a ring structure comprising a color conversion medium disposed on the first surface of the substrate, and a transparent lens positioned in overlying registration with the light emitting device and the ring structure, wherein the color conversion medium is spaced apart from and at least partially circumscribes the light emitting device. Arrays of such assemblies are also disclosed herein.

[0055] Referring to FIG. 8, a non-limiting exemplary optical assembly is depicted, which comprises a lens 100, a light source 111 , and a color conversion medium 112. The assembly may further comprise a ring structure 117 which may, in some

embodiments, comprise a first substrate 118 and a second substrate 119 defining a cavity 120 in which the color conversion medium 112 is contained. The ring structure 117 may further define a recess 121 in which the light source 111 may be at least partially positioned. A printed circuit board (PCB) 122 may also be provided, to which the light source 111 may be mounted. A heat sink 123 may also be attached to the PCB, which can include one or more thermal vias (not illustrated), for dissipating heat from the light source and/or color conversion medium. One or more adhesive layers (not illustrated) may optionally be present between two or more of the optical assembly components. Exemplary paths for light rays 110 and transmitted light rays 110' are included for illustrative purposes.

[0056] Lens 100 can comprise contact surface 101 and convex surface 102 as described above. Convex surface 102 can include a negative axiconic depression 104, which can have a vertex 107 pointing toward contact surface 101. According to various embodiments, the lens 100 may be positioned in overlying registration with the light source 111 and/or color conversion medium 112. In various embodiments, the vertex 107 of lens 100 may be aligned with a vertical centerline of the light source 111. In further embodiments, the outer perimeter of the lens 100 may be aligned with the outer perimeter of the color conversion medium 112. The contact surface 101 can be positioned in physical contact with ring structure 117 (e.g., first substrate 118) and/or may be adhered to the ring structure 117 by way of an adhesive layer (not illustrated). Although not illustrated in FIG. 8, contact surface 101 may include one or more recesses or cut-outs in which the light source 111 may be at least partially positioned (see, e.g., 106 in FIGS. 2A-B and 10).

[0057] According to various non-limiting embodiments, color conversion medium 112 may be arranged in a ring-shaped pattern around the light source 111 , e.g., such that the color conversion ring at least partially circumscribes the light source. While such a ring shape may not be appreciated from FIG. 8, which illustrates only a cross- section of the optical assembly, further examples of ring-shaped color conversion medium are illustrated in FIGS. 9 and 13A-B. It should be noted, however, that the term "ring" is not limited only to circular patterns, but may also include oval, square, rectangular, and other shapes. As such a "ring" may define any regular or irregular perimeter extending around the light source 111. Additionally, the "ring" or perimeter need not be continuous, as in the case of a single ring-shaped cavity. Rather, the ring may contain one or more gaps, as in the case of space between multiple cavities arranged in a ring-shaped pattern.

[0058] According to further embodiments, the ring of color conversion medium 112 may be spaced apart from the light source 111 , e.g., not in physical contact with the light source. However, in other non-limiting embodiments, the ring may at least partially contact the light source, including touching the sides or overlying the top of the light source. In certain embodiments, it may be advantageous to space the color conversion medium 112 away from the light source 111 to reduce heat transfer between these two components.

[0059] In various embodiments, the color conversion medium may be arranged in a plane extending around a perimeter of the light source. The color conversion medium may, in some embodiments, be in the same horizontal plane as the light source. If the color conversion medium is arranged in the same horizontal plane as the light source and circumscribes the light source, the light source may not directly emit light into the plane of the color conversion medium. Rather, light emitted directly from the light source may first reflect off of the convex surface of the transparent lens and may then be redirected back into the plane of the light source, e.g., the plane of the color conversion medium. As such, in non-limiting embodiments, the color conversion medium is not exposed to light rays directly emitted from the light source but, rather, to reflected rays redirected one or more times by the lens.

[0060] A ring of color conversion medium may be produced using a variety of structures and combinations thereof. For instance, as illustrated in FIG. 8, a ring structure 117 may be employed, which can comprise a first substrate 118 and a second substrate 119 sealed together to form at least one cavity 120 containing the color conversion medium 112. According to various embodiments, the first substrate 118 can contact the lens 100 and the second substrate 119 can contact the PCB 122, either directly or via an adhesive layer (or other intermediate layer). In certain embodiments, cavity 120 can be a ring-shaped cavity, e.g., extending continuously around a perimeter of the light source 111. Alternatively, cavity 120 can comprise a plurality of cavities arranged in a ring-shaped pattern. As shown in FIG. 13A, first and second substrates 118, 119 can be sealed together to form a plurality or array of ring-shaped cavities 120.

[0061] The optical assembly depicted in FIG. 8 can, in various embodiments, be repeated to form an optical array comprising an array of lenses 100, an array of light sources 111 , and an array of rings comprising color conversion medium 112. An exemplary two-dimensional array is depicted in FIG. 9. As previously noted, in some embodiments, the ring-shaped color conversion medium 112 may be spaced apart from the light source 111 by a distance d to reduce thermal interaction between these two components. Alternatively, although not illustrated, the color conversion ring may physically contact at least a portion of the light source 111.

[0062] FIG. 10 illustrates an additional non-limiting configuration for an optical assembly according to various embodiments of the disclosure. As depicted, the lens 100" can comprise at least one cavity 120' comprising the color conversion medium. As such, the lens 100" can serve as a first substrate and can be sealed or otherwise joined together with second substrate 119 to form ring structure 117'. In other non- illustrated embodiments, the color conversion medium may be separately sealed between two separate films, such as polymeric films (e.g., polyethylene terephthalate "PET"), and the separately sealed color conversion medium can be placed in cavity 120 (FIG. 8) or 120' (FIG. 10) [0063] FIG. 11 illustrates a further configuration for an optical assembly according to additional embodiments of the disclosure. In the depicted embodiment, ring structure 117 can comprise a first substrate 118 and a second substrate 119. The micro-light source 111' can comprise, for example, microLEDs, which can be deposited in optional cavities or wells (not labeled) in the first substrate 118. Micro-light sources 111' (e.g., microLEDs) can, in some embodiments, have a height of less than about 10 pm, such as ranging from about 3 pm to about 8 pm, from about 4 pm to about 7 pm , or from about 5 m to about 6 pm, including all ranges and subranges therebetween. An adhesive layer 124 may be disposed over the first substrate 118 and the micro-light sources 111' to bond the lens 100 to the first substrate 118. As such, the first substrate

118 can serve both as a PCB component upon which the micro-light sources may be mounted and as a sealing substrate in the ring structure 117. According to various embodiments, the first substrate 118 can be constructed from transparent materials.

[0064] FIG. 12 illustrates yet another configuration for an optical assembly according to further embodiments of the disclosure. As depicted, ring structure 117" can comprise a first substrate 118 and a second substrate 119, which can be sealed together by seal 125 with a color conversion micro-layer 112' disposed therebetween. A color conversion micro-layer 112' can, in some embodiments, have a thickness of less than about 20 pm, such as ranging from about 5 pm to about 20 pm, or from about 10 pm to about 15 pm, including all ranges and subranges therebetween.

[0065] In some embodiments, a glass frit may be used to form the seal 125 between the first and second substrates 118, 119. In other embodiments, a thin inorganic film may be melted (e.g., by laser heating) to form the seal 125. In further embodiments, the seal 125 can comprise a laser weld between the two substrates, e.g., without a glass frit or other intervening layer.

[0066] According to various embodiments, the first and second substrates 118,

119 may be transparent. A reflective layer 126 can be provided on one or more surfaces of the first and/or second substrates 118, 119 in regions that do not

correspond to or align with the color conversion micro-layer 112' and/or micro-light source 111'. One or more adhesive layers 124 may optionally be used to bond the lens 100 to the first substrate 118 and/or to bond the ring structure 117" to the PCB 122'. The light source can be a micro-light source 111' (e.g., microLED) mounted on a transparent PCB 122' (as illustrated) or, in alternative embodiments, can comprise a conventional LED mounted to a non-transparent PCB (not illustrated).

[0067] Also disclosed herein are color conversion assemblies comprising a transparent substrate and a reflective substrate sealed together to form at least one cavity comprising a color conversion medium, wherein the at least one cavity comprises a continuous ring-shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern. The disclosure additionally relates to color conversion assemblies comprising a sub-assembly comprising a first substrate and a second substrate sealed together to form at least one cavity comprising a color conversion medium, and a transparent lens positioned in overlying registration with the sub-assembly, wherein the at least one cavity comprises a continuous ring-shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern, and wherein the transparent lens comprises a convex surface and at least a portion of the convex surface comprises an equiangular spiral curvature. Optical assemblies comprising these color conversion assemblies and at least one light emitting device are further disclosed herein.

[0068] As illustrated in FIGS. 13A-B, a color conversion assembly can comprise a first substrate 118 sealed to a second substrate 119, the sealed substrates defining at least one cavity 120 containing a color conversion medium 112. As depicted in FIG. 13A, the assembly can comprise more than one cavity, e.g., an array of cavities 120. Moreover, as depicted in FIG. 13A, a single cavity 120 can be ring-shaped or, alternatively, a plurality of separate cavities can be assembled in a ring-shaped pattern (not illustrated). Such a color conversion assembly can be used, for instance, as a ring structure 117 in any of the embodiments depicted in FIGS. 8-12. As such, the at least one cavity 120 may at least partially circumscribe an optional aperture 128, which can be included, e.g., to accommodate a light source upon optical coupling to an LED array.

[0069] While FIG. 13A depicts an array of evenly spaced-apart circular cavities 120 of the same size and shape, it is to be understood that the cavities 120 may define rings having any other shape, such as square, oval, rectangular, and similar shapes. Additionally, it is to be understood that all cavities 120 in the array need not be identical. Moreover, it is not required that each cavity 120 comprise the same number or amount of color conversion medium, it being possible for this amount to vary from cavity to cavity and for some cavities to comprise no color conversion medium, for instance, to match a desired LED array.

[0070] With reference to any of FIGS. 8-13, the color conversion medium 112, 112' can comprise at least one color converting element. The color converting element may, in some embodiments, be suspended in an organic or inorganic matrix, such as a silicone or other suitable material. In certain embodiments, the color converting element may be suspended in a thermally conductive matrix. According to various

embodiments, the color converting material may be deposited as a layer having a thickness, for example, ranging from about 5 pm to about 400 pm, such as from about 10 pm to about 300 pm, from about 20 pm to about 200 pm, or from about 50 pm to about 100 pm, including all ranges and subranges therebetween. The at least one color converting element can be chosen, for example, from phosphors, quantum dots (QDs), and lumiphores such as fluorophores or light emitting polymers, and the like.

Exemplary phosphors can include, but are not limited to, red and green emitting phosphors, such as yttrium- and zinc sulfide-based phosphors, e.g., yttrium aluminum garnet (YAG), Eu²⁺ doped red nitride, and combinations thereof.

[0071] QDs can have varying shapes and/or sizes depending on the desired wavelength of emitted light. For example, the frequency of emitted light may increase as the size of the quantum dot decreases, e.g., the color of the emitted light can shift from red to blue as the size of the quantum dot decreases. When irradiated with blue, UV, or near-UV light, a quantum dot may convert the light into longer red, yellow, green, or blue wavelengths. According to various embodiments, the color converting element can be chosen from QDs that emit in red and green wavelengths when irradiated with blue, UV, or near-UV light.

[0072] It is possible, in various embodiments, for the at least one cavity 120 to comprise the same or different types of color converting element, e.g., elements emitting different wavelengths of light. For example, in some embodiments, a cavity can comprise color converting elements emitting both green and red wavelengths, to produce a red-green-blue (RGB) spectrum in the cavity. However, according to other embodiments, it is possible for an individual cavity to comprise only color converting elements emitting the same wavelength, such as a cavity comprising only green quantum dots or a cavity comprising only red phosphors. In further embodiments, a single cavity may be subdivided, e.g., like spokes on a wheel or pie pieces, with every other sub-cavity filled with green color converting elements and its complement filled with red color converting elements. Such an embodiment may be useful, for instance, in avoiding reconversion of light, e.g., blue converted to green and then green reconverted to red, or vice versa.

[0073] It is within the ability of one skilled in the art to choose the configuration of the cavity or cavities and the types and amounts of color conversion medium to place in each cavity to achieve a desired display or lighting effect. Moreover, although red and green emitting elements are discussed above, it is to be understood that any type of color converting element can be used, which can emit any wavelength of light including, but not limited to, red, orange, yellow, green, blue, or any other color in the visible spectrum (e.g., ~420-750nm). For instance, in solid-state lighting applications, quantum dots having various sizes may be combined to emulate the output of a black body, which may provide excellent color rendering.

[0074] In the embodiments discussed above with respect to FIGS. 2-13, the lens 100, 100', 100", first substrate 118, and/or second substrate 119 can, for example, comprise a transparent or substantially transparent material, such as a glass or plastic. As used herein, the term "transparent" is intended to denote that a lens, substrate, or material has an optical transmission of greater than about 80% in the visible region of the spectrum (~420-750nm). For instance, an exemplary transparent substrate or lens may have greater than about 85% optical transmittance in the visible light range, such as greater than about 90%, or greater than about 95%, including all ranges and subranges therebetween.

[0075] Suitable transparent materials may include, for instance, any glass known in the art for use in display and other electronic devices. Exemplary glasses can include, but are not limited to, aluminosilicate, alkali-aluminosilicate, borosilicate, alkali- borosilicate, aluminoborosilicate, alkali-aluminoborosilicate, and other suitable glasses. These substrates may, in various embodiments, be chemically strengthened and/or thermally tempered. Non-limiting examples of suitable commercially available substrates include EAGLE XG^® Lotus ' lris'^M Willow^® and Gorilla^® glasses from Corning Incorporated, to name a few. Glasses that have been chemically strengthened by ion exchange may be suitable as substrates according to some non-limiting embodiments. In other embodiments, polymeric materials, such as plastics (e.g., polymethylmethacrylate "PMMA," methylmethacrylate styrene "MS," or

polydimethylsiloxane "PDMS"), may be used as suitable transparent materials.

[0076] The second substrate 119 can, in non-limiting embodiments, be a reflective substrate, such as a metal, metal oxide, metal alloy, or mixtures thereof.

Alternatively, the second substrate can comprise a transparent material (e.g., glass, plastic, etc.) or a non-transparent material (e.g., ceramic, glass-ceramic, etc.) and the walls of cavity 120 (if present) can be coated with a reflective material (such as a metal or an oxide, alloy, or salt thereof, etc.). One or more reflective surfaces in cavity 120 may be advantageous in terms of ensuring that light is scattered in the desired (forward) direction. For example, any light back scattered by the color conversion medium can be scattered back in the desired direction by the reflective substrate (or reflective surface). Moreover, any blue (unconverted) light reflected off the reflective substrate (or reflective surface) may have a second opportunity to be converted to the desired wavelength as it passes back through the color conversion material.

[0077] In certain embodiments, it may be advantageous to construct the second substrate 119 from a thermally-conductive material, such as a metal and/or ceramic, to promote the dissipation of heat from the color conversion medium 112. Exemplary ceramic materials include aluminum nitride, aluminum oxide, beryllium oxide, boron nitride, and silicon carbide, to name a few. Exemplary reflective metals include, but are not limited to, Al, Au, Ag, Pt, Pd, Cu, other similar metals, and alloys thereof. According to various embodiments, the second substrate 119 can be constructed at least in part from inorganic substrates, such as inorganic substrates having a thermal conductivity greater than that of glass. For example, suitable inorganic substrates may include those with a relatively high thermal conductivity, such as greater than about 2.5 W/m-K (e.g., greater than about 2.6, 3, 5, 7.5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, or 100 W/m-K), for instance, ranging from about 2.5 W/m-K to about 100 W/m-K, including all ranges and subranges therebetween. In some embodiments, the thermal conductivity of the inorganic substrate can be greater than 100 W/m-K, such as ranging from about 100 W/m-K to about 300 W/m-K (e.g., greater than about 100, 1 10, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 W/m-K), including all ranges and subranges therebetween.

[0078] In additional embodiments, with reference to FIGS. 8-13, a hermetic seal can be used to join the first and second substrates (ring structures 117, 117") and/or the lens and the second substrate (ring structure 117'). Hermetic seals can also be used to join any other components of the optical assembly, such as bonding the lens to the ring structure, etc. For example, the substrates and/or lenses can be hermetically sealed such that the ring structures 117, 117', 117" are impervious or substantially impervious to water, moisture, air, and/or other contaminants. By way of non-limiting example, a hermetic seal can be configured to limit the transpiration (diffusion) of oxygen to less than about 10^"2 cm³/m²/day (e.g., less than about 10^"3/cm³/m²/day), and limit transpiration of water to about 10^"2 g/m²/day (e.g. , less than about 10^"3, 10^"4, 10^"5, or 10^"6 g/m²/day). In various embodiments, a hermetic seal can substantially prevent water, moisture, and/or air from contacting the components (e.g., color conversion medium and/or light source) protected by the hermetic seal.

[0079] Instead of transmitting the light directly through the color conversion medium ("transmission" mode), the optical assemblies disclosed herein may be configured such that light emitted by the light source is reflected one or more times, e.g., using a lens disclosed herein, to spread the light over a larger area before it strikes the color conversion medium ("reflectance" mode). As such, the optical flux within the device may be reduced by more than two orders of magnitude. In other words, reflected light impinging on the color conversion medium has an intensity less than 1 % of that of the light originally transmitted from the light source. Moreover, because light may reflect from a reflecting surface underneath the color conversion medium, a reflectance mode configuration may have the added benefit of passing light through the color conversion medium more than once, thus increasing the chance that it is converted to a different wavelength.

[0080] Moreover, using a "remote" configuration, in which the color conversion medium is spaced apart from the light source, in combination with "reflectance" mode not only reduces the optical flux to which the medium and/or matrix is exposed, but also provides additional heat sink pathways for dissipating any generated heat.

Furthermore, a "remote" configuration has an additional advantage of allowing the LED to run at cooler temperatures and, thus, more efficiently, because it does not need to serve as a thermal path for cooling the color conversion medium (e.g., as in the case of conformal phosphor coatings). The lifetime of the optical assembly can therefore be extended as compared to prior art devices due to one or more of the above advantages.

Devices

[0081] The lenses and optical assemblies depicted in FIGS. 2-13 can be used in a variety of applications including, but not limited to, display and lighting applications. For instance, an illuminating device, such as a luminaire or solid state lighting device, can comprise an optical assembly disclosed herein. In certain embodiments, the optical assemblies can be used alone or in an array to mimic the broadband output of the sun. Such assemblies can comprise, for example, color converting elements of various types and/or sizes emitting at various wavelengths, such as visible wavelengths ranging from 420-750nm.

[0082] For instance, a "white" LED can be produced by coating an LED emitting blue light with a silicone/phosphor slurry. However, silicone may darken over time after prolonged exposure to the LED optical flux and heat. The optical assemblies disclosed herein may be used in such lighting devices to reduce the optical flux to which the color conversion medium and/or matrix is exposed and/or to provide additional or alternative thermal pathways to dissipate the heat generated by the LED and/or color conversion medium. Embodiments comprising one or more glass substrates may also have the added advantage of remaining optically clear for longer periods of time as compared to plastic substrates.

[0083] According to various embodiments, an optical assembly disclosed herein can be incorporated into a backlight unit (BLU) in a display device, such as an LCD. As illustrated in FIG. 14, a BLU 127 and liquid crystal (LC) panel 129 can be incorporated into a display device, such as a television, computer, handheld device, or the like. The BLU 127 can comprise an array of light sources 111 mounted to a PCB 122, which may be attached to a heat sink 123. As illustrated, the PCB 122 may be equipped with a plurality of thermal vias 130, which can be positioned to provide heat sink pathways for the light sources 111 and color conversion medium 112. Thermal vias 130 may comprise, in some embodiments, holes or apertures in the PCB 122 filled with a conductive material (e.g., metals such as Cu, Ag, etc.), which can allow for heat transfer from one side of the PCB 122 to the other side and into the heat sink 123 (if present). While a single heat sink 123 is illustrated in FIG. 14, it is also possible to provide more than one heat sink 123. For instance, separate heat sinks can be provided for the color conversion medium 112 and for the LEDs 111 , which may further isolate the color conversion medium from heat generated by the LEDs.

[0084] As depicted in FIG. 14, an array of lenses 100 can be optically coupled to an array of light sources 111. One or more adhesive layers 124 can be optionally included to improve adhesion between various components of the BLU 127 and/or between the BLU 127 and the LC panel 129. Additional layers may be provided between the BLU 127 and the LC panel 129, such as a diffuser layer 131 , and/or additional layers may be provided between lenses 100, such as reflecting walls 132. In some embodiments, it may not be desirable to completely isolate the individual optical assemblies from one another, and the additional layers 131 , 132 may correspondingly be modified or removed to allow for a desired amount of light leakage between the assemblies.

[0085] Further disclosed herein are light conversion devices comprising a transparent substrate having a first surface and an opposing light emitting surface, a color conversion medium disposed on the first surface, and a reflective layer disposed on the first surface and encapsulating at least a portion of the color conversion medium. Exemplary light conversion devices include, for instance, light guide plates (LGPs) and light guide assemblies. For instance, as depicted in FIGS. 15A-B, a first surface 133 of an LGP 134 may be patterned with a color conversion medium 112, which can be sealed or encapsulated with a protective layer, such as reflective layer 135. In non- limiting embodiments, the reflective layer can comprise a metallic film, such as a film comprising one or more Al, Au, Ag, Pt, Pd, Cu, and alloys thereof. In certain

embodiments, the reflective layer 135 may comprise a material with high thermal conductivity, e.g., capable of dissipating heat from the color conversion medium. Furthermore, the reflective layer 135 may comprise a ductile material capable of expanding and/or stretching under thermal stress (e.g., due to thermal expansion of the color conversion material) without developing cracks or pinholes. The reflective layer 135 can thus serve both as a heat sink for dissipating heat from the color conversion medium 112 and/or as a hermetic barrier preventing degradation of the color conversion medium 112 by moisture and/or air.

[0086] A light source 111 may be coupled to an edge (light incident) surface of the LGP 134. Optionally, a reflector 140 may be attached to an opposite edge of the LGP. Light 110 propagating through the LGP 134 may reflect within the LGP due to TIR until striking a region comprising the color conversion medium 112, at which point it may be scattered forward as transmitted light 110' through the light-emitting (second) surface 136. The color conversion medium may also modify the light 110, such that transmitted light 110' has a different wavelength than the original wavelength of light 110. As such, the light guide assembly depicted in FIGS. 15A-B may integrate various layers that are conventionally included as separate BLU components. For instance, the color conversion medium can be integrated on the first surface 133 of the LGP 134, rather than being supplied as a separate film, either on the light source 111 or in the BLU stack. Furthermore, the reflective layer 135 may also be integrated on the first surface 133 instead of being included as an additional component separate from the LGP 134 in traditional BLU stacks.

[0087] Conventional LGPs may be optically coupled to white LEDs, e.g., blue LEDs coated with a color conversion medium such as a silicone/phosphor slurry that converts the blue light to white light. White paint or other light scattering features may be provided on a surface of the LGP to scatter light in a desired forward direction.

However, using the integrated color converter configuration disclosed herein, it may be possible to replace the conventional white LED with a blue LED and to replace the white paint with color conversion material encapsulated by a reflective layer. The integrated color conversion medium on the LGP surface may thus serve the dual function of scattering blue light forward in the desired direction and converting the blue light to white light. Thus, in certain embodiments, a traditional phosphor-coated white LED can be replaced by a blue LED coupled to a LGP patterned with QDs. Since QDs have a narrower emission spectrum than phosphors, the resulting assembly may have an improved color gamut. Of course, in other embodiments, the LGP may be patterned with color converting elements other than QDs, such as phoshors, fluorophores, and the like.

[0088] While FIG. 15A depicts an LGP comprising a continuous reflective layer 135, certain embodiments may also incorporate a discontinuous reflective layer 135', such as that illustrated in FIG. 15B. Because metals, such as aluminum, may be slightly absorbing, a continuous reflective metallic coating may result in slight attenuation of the LGP. As such, in some embodiments, the reflective layer may be provided only in regions corresponding to deposits of color conversion medium 112. As such, regions 137 of the LGP may have a glass/air or plastic/air interface, allowing for greater TIR. Additionally, although not illustrated, the surface 133 of the LGP 134 corresponding to regions 137 may be provided with other light scattering features, such as white scattering particles, which may be used to achieve a desired color balance for light transmitted by the LGP 134. Light scattering features, such as ΤΊΟ₂ particles, may be printed on the surface 133 of the LGP 134 and/or light scattering features may be provided by etching or laser damaging the surface 133 of the LGP 134.

[0089] In alternative embodiments, as depicted in FIG. 15C, an ink layer 138 may be provided between the color conversion medium 112 and the reflective layer

135. The ink layer may 138 comprise, for example, reflective white inks such as metal oxides (e.g., ΤΊΟ₂), and may serve to partially or completely obscure the reflective layer 135 from view. If desired, the ink layer 138 can be applied along the entire length of surface 133, even in regions where there is no color conversion medium 112, as shown in FIG. 15C. Alternatively, ink layer 138 may be provided only in regions comprising color conversion medium 112.

[0090] According to various embodiments, the color conversion medium and/or light scattering features may be patterned in a suitable density on surface 133 so as to produce substantially uniform light output intensity across light-emitting surface 136 of the LGP. In other embodiments, the color conversion medium and/or light scattering features may be patterned to produce non-uniform light output intensity across surface

136. In certain embodiments, a density of the color conversion medium and/or light scattering features proximate the light source 111 may be lower than a density at a point further removed from the light source, or vice versa, such as a gradient from one end to another, as appropriate to create the desired light output distribution across the LGP.

[0091] Configurations other than edge-lit LGPs are also possible and envisioned as falling within the scope of the application. For instance, back-lit LGPs may also benefit from an integrated color conversion medium as described herein. Moreover, the light conversion devices are not limited only to BLU applications, but may also be useful in solid state lighting applications. For illustrative purposes, three exemplary non- limiting lighting configurations are depicted in FIGS. 16A-C. A large number of lighting configurations can be imagined using a variety of light sources 111 (e.g., linear lamps such as fluorescent bulbs), substrate 139 shapes and/or sizes (e.g., prisms), and/or reflector 140 positions. The type and/or position of the color conversion medium 112 and reflective layer 135 may also be varied from configuration to configuration.

Methods

[0092] Disclosed herein are methods for making a light conversion device, the methods comprising patterning a color conversion medium on a first surface of a substrate and depositing a protective layer on the first surface to encapsulate the color conversion medium, wherein one of the substrate or the protective layer comprises a reflective material. Also disclosed herein are methods of making an optical assembly comprising depositing the color conversion medium in a ring-shaped pattern, positioning a light emitting device within a perimeter of the ring-shaped pattern, and positioning a transparent lens in overlying registration with the light emitting device and color conversion medium.

[0093] In various embodiments, the substrate may be a transparent substrate and the protective layer may comprise at least one metal. Alternatively, the substrate may be a reflective substrate comprising at least one metal and the protective layer may comprise at least one transparent inorganic oxide. Further, the substrate may comprise at least one cavity having at least one reflective surface and the protective layer may comprise at least one transparent inorganic oxide. [0094] The color conversion medium can be deposited on the first surface of the substrate using any method known in the art. Suitable deposition methods can include printing, such as inkjet printing, screen printing, microprinting, and the like, coating, such as spin coating, slot coating, dip coating, and the like, drop-casting, pipetting, or any combination thereof. In certain embodiments, droplets of color conversion medium suspended in one or more solvents can be deposited onto the first surface in any desired pattern. The solvent(s) may optionally be removed by drying at ambient or elevated temperatures. As used herein, the term "patterning" is intended to denote that the color conversion medium is present on the first surface in any given pattern or design, which may, for example, be random or arranged, repetitive or non-repetitive, uniform or non-uniform. As discussed above, a pattern can also comprise a gradient from one end of the substrate to the other.

[0095] Methods for depositing the protective layer can include, for example, sputtering or vapor deposition processes. For instance, the color conversion medium can be deposited on a first surface of a transparent substrate, such as a glass or plastic substrate, and a protective metallic film can subsequently be sputtered or evaporated onto the first surface to at least partially encapsulate the color conversion medium. Alternatively, the color conversion medium can be deposited on a first surface of a reflective substrate and a protective inorganic oxide layer can be sputtered or evaporated onto the first surface. In various embodiments, the substrate and protective layer may form a hermetic capsule in which the color conversion medium is contained. In additional embodiments, the substrate may comprise one or more cavities in which the color conversion medium may be deposited. Cavities can be provided in the substrate, e.g., by pressing, molding, cutting, or any other suitable method. According to additional embodiments, the protective layer may have a thickness ranging from about 0.1 pm to about 10 pm, such as from about 0.5 pm to about 9 pm, from about 1 pm to about 8 pm, from about 2 pm to about 7 pm, from about 3 pm to about 6 pm, or from about 4 pm to about 5 pm, including all ranges and subranges therebetween.

[0096] Color conversion assemblies disclosed herein can be manufacturing using a variety of methods. For example, the color conversion medium can be encapsulated between first and second substrates using a pair of rollers embossed with recesses corresponding to the desired cavity shape (e.g., a ring shape or ring pattern). In various embodiments, the embossed rollers may be operated at a temperature and/or pressure sufficient to promote fusion of the first and second substrates. In the case of a ring-shaped cavity or pattern, additional processing steps may include providing a hole or aperture in the center of the ring. Such a hole may be cut or punched into the first and second substrates using any method known in the art.

[0097] Alternative methods for forming the color conversion assemblies may include molding. For example, one or more substrates making up the ring structure may be molded to include at least one cavity. In some embodiments, the transparent lens may be molded to include at least one cavity. After filing the cavity with color conversion medium, the molded substrate(s) and/or lens may then be bonded together, e.g., using an adhesive or other sealing technique, such as laser sealing. Sputtering and vapor deposition processes discussed above with respect to the light conversion devices may also be suitable for forming the color conversion assemblies disclosed herein.

[0098] Yet another method for forming the color conversion assemblies can include depositing a color conversion medium on a substrate in a desired pattern (e.g.,

[0099] It will be appreciated that the various disclosed embodiments may involve particular features, elements or steps that are described in connection with that particular embodiment. It will also be appreciated that a particular feature, element or step, although described in relation to one particular embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.

[00100] It is also to be understood that, as used herein the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a cavity" includes examples having one such "cavity" or two or more such "cavities" unless the context clearly indicates otherwise. Similarly, a "plurality" or an "array" is intended to denote two or more, such that an "array of cavities" or a "plurality of cavities" denotes two or more such cavities. [00101] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[00102] All numerical values expressed herein are to be interpreted as including "about," whether or not so stated, unless expressly indicated otherwise. It is further understood, however, that each numerical value recited is precisely contemplated as well, regardless of whether it is expressed as "about" that value. Thus, "a dimension less than 10 mm" and "a dimension less than about 10 mm" both include embodiments of "a dimension less than about 10 mm" as well as "a dimension less than 10 mm."

[00103] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.

[00104] While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase "comprising," it is to be understood that alternative embodiments, including those that may be described using the transitional phrases "consisting" or "consisting essentially of," are implied. Thus, for example, implied alternative embodiments to a method comprising A+B+C include embodiments where a method consists of A+B+C, and embodiments where a method consists essentially of A+B+C.

[00105] It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the disclosure may occur to persons skilled in the art, the disclosure should be construed to include everything within the scope of the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1 . An optical assembly comprising:

a light emitting device disposed on a first surface of a substrate;

a ring structure comprising a color conversion medium disposed on the first surface of the substrate; and

a transparent lens positioned in overlying registration with the light emitting device and the ring structure;

wherein the color conversion medium is spaced apart from and at least partially circumscribes the light emitting device.

2. The assembly of claim 1 , wherein the ring structure comprises at least one cavity containing the color conversion medium.

3. The assembly of claim 2, wherein the at least one cavity is hermetically sealed.

4. The assembly of 2, wherein the at least one cavity comprises a continuous ring- shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern.

5. The assembly of claim 2, wherein the ring structure comprising a reflective surface and an opposing transparent surface, and wherein the reflective surface is in contact with the first surface of the substrate.

6. The assembly of claim 2, wherein the ring structure comprises a transparent substrate and a second substrate sealed together to form at least one cavity containing the color conversion medium.

7. The assembly of claim 6, wherein the transparent substrate is chosen from glasses and polymers, and wherein the second substrate is a reflective substrate.

8. The assembly of claim 7, wherein the reflective substrate is chosen from metal, metal alloy, or metal oxide substrates or ceramic or glass-ceramic substrates

comprising at least one surface coated with a metal, metal alloy, or metal oxide layer.

9. The assembly of claim 1 , wherein the transparent lens comprises at least one cavity containing the color conversion medium, and wherein the ring structure is defined by the transparent lens and a second reflective substrate.

10. The assembly of claim 1 , wherein the ring structure comprises a first transparent substrate and a second transparent substrate sealed together with a micro-layer of color conversion medium disposed therebetween, the micro-layer having a thickness ranging from about 5 pm to about 20 pm.

1 1 . The assembly of claim 1 , wherein transparent lens comprises a convex surface, and wherein at least a portion of the convex surface comprises an equiangular spiral curvature.

12. The assembly of claim 1 , wherein the transparent lens is chosen from single- lobed and double-lobed linear lenses.

13. The assembly of claim 1 , wherein the transparent lens comprises a contact surface, a convex surface, and a central region disposed therebetween, and wherein the convex surface comprises a negative axiconic depression extending into the central region.

14. The assembly of claim 13, wherein the contact surface is a rotationally symmetric planar surface and the convex surface is a rotationally symmetric hemi-spherical surface.

15. The assembly of claim 13, wherein the negative axiconic depression comprises a hollow conical region positioned in overlying registration with the light emitting device, and wherein a vertex of the hollow conical region points toward the contact surface of the transparent lens.

16. The assembly of claim 1 , wherein the color conversion medium comprises at least one color converting element chosen from phosphors, quantum dots, and lumiphores.

17. The assembly of claim 1 , wherein the color conversion medium is disposed on the first surface of the substrate such that light emitted from the light emitting device and reflected by the convex surface of the transparent lens is incident upon at least a portion of the color conversion medium.

18. The assembly of claim 1 , wherein the color conversion medium is arranged in a plane extending around a perimeter of the light emitting device, and wherein the light emitting device does not directly emit light into the plane of the color conversion medium.

19. The assembly of claim 1 , wherein the color conversion medium does not physically contact the light emitting device.

20. The assembly of claim 1 , further comprising at least one heat sink in contact with a second surface of the substrate.

21 . An optical array comprising a plurality of assemblies according to claim 1 .

22. A display device, electronic device, or lighting device comprising the optical assembly of claim 1 or the optical array of claim 21 .

23. A color conversion assembly comprising:

a sub-assembly comprising a first substrate and a second substrate sealed together to form at least one cavity comprising a color conversion medium; and a transparent lens positioned in overlying registration with the sub-assembly, wherein the at least one cavity comprises a continuous ring-shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern; and

wherein the transparent lens comprises a convex surface and at least a portion of the convex surface comprises an equiangular spiral curvature.

24. The assembly of claim 23, wherein the first substrate is a transparent substrate and the second substrate is a reflective substrate.

25. The assembly of claim 23, wherein a contact surface of the transparent lens is in physical contact with the transparent substrate.

26. The assembly of claim 25, wherein the contact surface is a rotationally symmetric planar surface and the convex surface is a rotationally symmetric hemi-spherical surface.

27. The assembly of claim 23, wherein the convex surface further comprises a negative axiconic depression having a vertex pointing toward a contact surface of the transparent lens.

28. The assembly of claim 23, wherein the color conversion medium comprises at least one color converting element chosen from phosphors, quantum dots, and lumiphores.

29. The assembly of claim 23, wherein the first and second substrates are

hermetically sealed together.

30. An optical assembly comprising the assembly of claim 23 and at least one light emitting device.

31 . The optical assembly of claim 30, wherein the at least one cavity circumscribes the at least one light emitting device.

32. The optical assembly of claim 30, wherein the at least one light emitting device is positioned in a recess in the first substrate of the sub-assembly.

33. The optical assembly of claim 32, wherein the at least one light emitting device is a microLED.

34. A display device, electronic device, or lighting device comprising the color conversion assembly of claim 23 or the optical assembly of claim 30.

35. A color conversion assembly comprising a transparent substrate and a reflective substrate sealed together to form at least one cavity comprising a color conversion medium, wherein the at least one cavity comprises a continuous ring-shaped cavity or a plurality of cavities arranged in a discontinuous ring-shaped pattern.

36. The assembly of claim 35, wherein the transparent substrate is chosen from glasses and polymers, and wherein the reflective substrate is chosen from metal, metal alloy, or metal oxide substrates or ceramic or glass-ceramic substrates comprising at least one surface coated with a metal, metal alloy, or metal oxide layer.

37. The assembly of claim 35, wherein the color conversion medium comprises at least one color converting element chosen from phosphors, quantum dots, and lumiphores.

38. An optical assembly comprising the color conversion assembly of claim 35 and at least one light emitting device.

A light conversion device comprising: a transparent substrate having a first surface and an opposing light emitting surface;

a color conversion medium disposed on the first surface; and

a reflective layer disposed on the first surface and encapsulating at least a portion of the color conversion medium.

40. The device of claim 39, wherein the color conversion medium comprises at least one color converting element chosen from phosphors, quantum dots, and lumiphores.

41 . The device of claim 39, wherein the transparent substrate is chosen from glasses and polymers, and wherein the reflective layer comprises at least one metallic film.

42. The device of claim 41 , wherein the metallic film is discontinuous.

43. The device of claim 41 , further comprising at least one light scattering feature disposed on the first surface in at least one region corresponding to a void in the discontinuous metallic film.

44. The device of claim 41 , further comprising a white reflective layer disposed between the color conversion medium and the metallic film.

45. The device of claim 44, wherein the white reflective layer is discontinuous.

46. A light guide assembly comprising the device of claim 39 optically coupled to at least one light source.

47. The light guide assembly of claim 46, wherein the at least one light source is optically coupled to the first surface of the transparent substrate.

48. The light guide assembly of claim 46, wherein the at least one light source is optically coupled to an edge surface of the transparent substrate.

49. The light guide assembly of claim 48, wherein the color conversion medium is patterned on the first surface in a gradient with increasing density as a function of distance from the at least one light source.

50. The light guide assembly of claim 46, wherein the at least one light source is a light emitting diode emitting ultraviolet, near-ultraviolet, or blue light.

51 . A method of making a light conversion device, the method comprising:

patterning a color conversion medium on a first surface of a substrate and depositing a protective layer on the first surface to encapsulate the color conversion medium, wherein one of the substrate or the protective layer comprises a reflective material.

52. The method of claim 51 , wherein the substrate is a transparent substrate chosen from glasses and polymers, and wherein the protective layer comprises at least one metal.

53. The method of claim 51 , wherein the substrate is a reflective substrate

comprising at least one metal and the protective layer comprises at least one

transparent inorganic oxide.

54. The method of claim 51 , wherein the substrate comprises at least one cavity having at least one reflective surface and the protective layer comprises at least one transparent inorganic oxide.

55. The method of claim 51 , wherein the protective layer is deposited by vapor deposition or sputtering.

56. The method of claim 51 , wherein the color conversion medium comprises at least one color converting element chosen from phosphors, quantum dots, and lumiphores.

57. The method of claim 51 , wherein the color conversion medium is deposited on the first surface in a ring-shaped pattern.

58. The method according to claim 57, further comprising forming an optical assembly by positioning a light emitting device within a perimeter of the ring-shaped pattern and positioning a transparent lens in overlying registration with the light emitting device and color conversion medium.