CN110809696A

CN110809696A - Light guide including equiangular helical curvature and apparatus including the same

Info

Publication number: CN110809696A
Application number: CN201880044178.2A
Authority: CN
Inventors: S·巴苏; T·J·奥斯雷; W·R·特鲁特纳
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2017-05-03
Filing date: 2018-05-03
Publication date: 2020-02-18
Also published as: KR20190138316A; TW201901209A; WO2018204557A1; JP2020518966A

Abstract

The light guide includes at least one light emitting surface and at least one light coupling surface, at least a portion of which has an equiangular helical curvature. Also disclosed herein are optical assemblies including at least one light source optically coupled to a light guide, as well as display devices, lighting devices, and electronic devices including such assemblies.

Description

Light guide including equiangular helical curvature and apparatus including the same

Priority claims are claimed in this application from 35u.s.c. § 119 claiming us provisional application serial No. 62/500,775 filed on 3.5.2017 and us provisional application serial No. 62/592,147 filed on 29.11.2017, the contents of each provisional application being based thereon and the contents of these provisional applications being incorporated herein by reference in their entirety.

Technical Field

The present disclosure relates generally to light guides comprising at least one light coupling surface having a equiangular helical curvature, and display devices and illumination devices comprising such light guides.

Background

Liquid Crystal Displays (LCDs) are commonly used in a variety of electronic devices such as mobile phones, portable computers, electronic flat devices, televisions, and computer monitors. Conventional LCDs typically include a blue Light Emitting Diode (LED) and a color conversion element, such as a phosphor or Quantum Dots (QDs). LEDs may also be used in conjunction with color conversion elements in lighting applications, such as luminaires. For example, blue light from an LED may be directed through a color conversion medium that may convert some of the light into green and/or red light as the light passes through. The combination of blue, green and red light is perceived by the human eye as white light.

Color conversion elements such as phosphors and QDs are not 100% quantum efficient in converting light, and some light energy may be absorbed as heat by the color conversion element. In addition, the color conversion process itself generates heat due to Stokes shift, for example, when converting shorter wavelengths to longer wavelengths. In some cases, up to 20% -40% of the absorbed light is converted to heat. Since excessive heat may degrade the color conversion element, it is important to establish a sufficient cooling or heat dissipation path to dissipate the generated heat and maintain the color conversion element within a desired operating temperature. While the phosphor material may be capable of operating at moderate temperatures (e.g., up to about 300 ℃), the QD material is highly temperature sensitive and may experience degradation at temperatures greater than about 100 ℃.

Due to the temperature sensitivity of the QDs, conventional backlight units (BLUs) are typically configured to avoid close proximity and/or direct contact between the QDs and the LEDs. Such a configuration is referred to as a "remote" configuration. For example, as shown in the LCD assembly of fig. 1, the QDs are typically provided in the form of glass or polymer tubes, capillaries, sheets or films, such as a QD reinforcing film (QDEF)1, which may be placed over (but not in direct physical contact with) an array of LEDs 2, which array of LEDs 2 is disposed on a Printed Circuit Board (PCB) 3. Accordingly, light 4 emitted from the LED 2 may pass through the QDs as it travels to the Liquid Crystal (LC) panel 5. The BLU 6 may also include a heat sink 7 attached to the PCB, which heat sink 7 may dissipate heat generated by the LEDs.

However, these components may not provide sufficient cooling because heat from the QDs is primarily dissipated by free or forced convective air 8 passing through the gap between the LEDs and the QDEF. QDEF is itself a relatively poor conductor of heat and does not benefit from direct thermal contact with the heat sink 7. In this way, the LCD assembly may be operated at lower light intensities and/or powers in order to protect the QDs from thermal degradation, which may undesirably result in an overall reduction in display or illumination brightness. In addition, such assemblies can result in significant material waste because the QDs are uniformly dispersed throughout the LED array, rather than merely being discretely positioned over each individual LED in the array.

It would therefore be advantageous to provide an optical assembly comprising a patterned color conversion medium that can reduce material waste, thereby reducing the cost of such devices. It would also be advantageous to provide an optical assembly that includes a heat sink path or other cooling mechanism that can dissipate heat generated by the color conversion medium. Furthermore, it would be advantageous to provide an optical assembly having a reduced overall thickness.

Disclosure of Invention

In various embodiments, the present disclosure is directed to a light guide comprising at least one light emitting surface and at least one light coupling surface, wherein at least a portion of the at least one light coupling surface comprises an equiangular spiral curvature.

In some embodiments, a light guide can include a plate including a first major surface, an opposing second major surface, and at least one edge surface, wherein the at least one edge surface includes a light coupling surface. In an alternative embodiment, the light guide can include a disk including a first major surface, an opposing second major surface; and an edge surface, wherein the edge surface comprises a light coupling surface. The second major surface of the light guide plate or tray may comprise a light emitting surface. The first major surface of the light guide plate or tray may be patterned with at least one of a color conversion medium, light scattering features, and a reflective material. The reflective layer may at least partially encapsulate the color conversion medium patterned on the first major surface.

According to various embodiments, a light guide may include a ring including an inner wall surface, an outer wall surface, and at least one edge surface, wherein the at least one edge surface includes a light coupling surface. In some embodiments, the outer wall surface comprises a light emitting surface. In further embodiments, the ring comprises a hollow cylinder. According to a further embodiment, a light guide can include a rod including a first end face, a second end face, an outer wall surface, and an edge surface, wherein the edge surface includes a light coupling surface. At least one of the first end face, the second end face, and the outer wall surface may include a light emitting surface.

Also disclosed herein are optical assemblies comprising at least one light source optically coupled to a light guide, such as to at least one light coupling surface. In various embodiments, at least one light source is bonded to the printed circuit board. In certain embodiments, the optical assembly can further include a transparent substrate including a major surface patterned with at least one of a color conversion medium, a light scattering feature, and a reflective material. The reflective layer may at least partially encapsulate the color conversion medium patterned on the major surface of the transparent substrate. According to a non-limiting embodiment, the optical assembly may further include a diffusing layer located adjacent to the at least one light emitting surface of the light guide.

For example, the optical assembly may include a stack having a thickness of less than about 10mm or less than about 5 mm. The light guide and/or the transparent substrate may comprise glass, plastic, or a combination thereof. Also disclosed herein are display devices, lighting devices, and electronic devices, including such light guides and optical assemblies or arrays of optical assemblies.

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.

It is to be understood that both the foregoing general description and the following detailed description present embodiments of the disclosure, and are intended to provide an overview or framework for understanding the nature and character of the 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.

Drawings

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

FIG. 1 illustrates an exemplary LCD assembly;

2A-2C illustrate side, top, and perspective views of a light guide plate according to an embodiment of the present disclosure;

3A-3C illustrate side, top, and perspective views of an optical disk according to an embodiment of the present disclosure;

4A-4C illustrate side, top, and perspective views of a light guiding ring according to an embodiment of the present disclosure;

fig. 5A-5C illustrate side, top, and perspective views of a light guide rod according to embodiments of the present disclosure;

FIG. 6 illustrates total internal reflection within a light guide plate including at least one edge having an equiangular spiral curvature according to further embodiments of the present disclosure;

FIG. 7 illustrates a coordinate system for constructing a constant angle of incidence curve in accordance with various embodiments of the present disclosure;

FIG. 8 illustrates a constant angle of incidence curve according to additional embodiments of the present disclosure;

FIG. 9 illustrates a light guide including a truncated light coupling surface having an equiangular spiral curvature;

FIG. 10 illustrates a light guide including a light coupling surface with two equiangular helical curvature profiles;

11A-11B illustrate ray tracing paths for a light coupling surface having a single equiangular spiral curvature profile and a double equiangular spiral curvature profile;

FIGS. 12A-12B illustrate enlarged views of the ray tracing paths depicted in FIGS. 11A-11B;

FIG. 13 is a chart illustrating light source alignment tolerances for a light guide including a light coupling surface having a single equiangular spiral curvature profile and a double equiangular spiral curvature profile;

FIG. 14A illustrates a side view of a light guide plate having a major surface patterned with a color conversion medium and including a reflective layer;

FIG. 14B illustrates a side view of a light guide plate having its major surface patterned with a color conversion medium and a reflective material;

fig. 14C illustrates a side view of a substrate having a major surface patterned with a color conversion medium and including a reflective layer;

FIG. 15 illustrates an optical assembly including interlocked light guides and a substrate;

FIG. 16A illustrates a top view of a substrate patterned with a color conversion medium;

FIG. 16B illustrates a top view of a substrate patterned with a color conversion medium and a reflective material;

FIG. 16C illustrates a perspective view of a multilayer substrate including a color conversion layer and a reflective layer;

FIG. 17 illustrates an optical assembly according to various embodiments of the present disclosure;

18-19 illustrate arrays of optical assemblies according to other embodiments of the present disclosure;

20A-20C illustrate optical radiation intensity profiles of optical assemblies according to particular embodiments of the present disclosure;

21A-21D illustrate optical radiation intensity profiles of optical assemblies according to further embodiments of the present disclosure;

FIG. 22 illustrates an optical assembly according to various embodiments of the present disclosure; and

fig. 23A-23B illustrate output irradiance profiles of optical assemblies according to non-limiting embodiments of the present disclosure.

Detailed Description

Embodiments of the present disclosure will now be discussed with reference to fig. 2-22, which illustrate exemplary embodiments of light guides, optical assemblies, their components, and their features or characteristics. Display devices and lighting devices including these components are also disclosed herein. The following general description is intended to provide an overview of the claimed components and devices, and various aspects will be discussed more particularly throughout this disclosure with reference to non-limiting described embodiments, which are interchangeable with one another within the scope of the disclosure.

Light guide member

Disclosed herein are light guides comprising at least one light emitting surface and at least one light coupling surface, the at least one light coupling surface comprising at least a portion having an equiangular helical curvature. Suitable materials from which the light guide may be constructed include optically transparent materials such as glass and plastic. As used herein, the term "transparent" is intended to mean a light guide, substrate, or material having an optical transmission greater than about 80% in the visible region of the spectrum (420-750 nm), measured over a path length of 1 mm. For example, an exemplary transparent light guide, substrate, or material may have an optical transmission greater than about 85% in the visible range, such as greater than about 90% or greater than about 95%, including all ranges and subranges therebetween.

Suitable transparent materials may include, for example, any glass known in the art for displays and other electronic devices. Exemplary glasses may include, but are not limited to, aluminosilicates, alkali aluminosilicates, borosilicates, alkali borosilicates, aluminoborosilicates, alkali aluminoborosilicatesSalt and other suitable glasses. In various embodiments, the substrates may be chemically strengthened and/or thermally tempered. Non-limiting examples of suitable commercially available substrates include EAGLE XG from corning,

、Lotus^TM、Iris^TM、

andglass, to name a few. According to some non-limiting embodiments, glasses that have been chemically strengthened by ion exchange may be suitable as substrates. In other embodiments, a polymeric material, such as a plastic (e.g., polymethylmethacrylate "PMMA", methylmethacrylate styrene "MS", or polydimethylsiloxane "PDMS") may be used as a suitable transparent material.

2-5 depict various non-limiting light guides 100A-100D, each light guide including at least one light emitting surface and at least one light coupling surface including at least a portion having an equiangular spiral curvature. Referring to FIG. 2, the light guide 100A may be in the form of a sheet or plate that includes at least one edge surface 103. The Light Guide Plate (LGP)100A includes a first major surface 101 and an opposite second major surface 102, both of which may serve as light emitting surfaces. In the depicted embodiment, the second major surface 102 may serve as a light emitting surface and the edge surface 103 may serve as a light coupling surface. At least a portion of the edge surface 103 is shaped to produce an equiangular helical curvature. Although fig. 2A-2C depict a symmetric rectangular LGP 100A including two light coupling surfaces (e.g., edge surfaces 103), it should be understood that the LGP 100A may include any regular or irregular polygonal shape, including symmetric and asymmetric shapes having fewer or more than 4 edges, such as triangles, squares, diamonds, trapezoids, pentagons, hexagons, and other suitable shapes. Shapes that include at least one curvilinear edge surface 103 are also contemplated herein. In addition, although the first and second

major surfaces

101, 102 are depicted as planar and parallel in fig. 2A-2C, it should be understood that each of these surfaces may include one or more axes of curvature and/or may not be parallel to each other.

As shown in fig. 3A-3C, the light guide 100B may also be in the form of a disk, including an edge surface 103. Similar to fig. 2A-2C, light guide plate 100B also includes a first major surface 101 and an opposing second major surface 102, both of which can serve as light emitting surfaces. In the depicted embodiment, the second major surface 102 may serve as a light emitting surface and the edge surface 103 may serve as a light coupling surface. At least a portion of the edge surface 103 is shaped to produce an equiangular helical curvature. Although fig. 3A-3C depict a symmetrical circular optical disk 100B, it should be understood that the disk 100B may include any regular or irregular shape (such as circular, elliptical, and other free-form curvilinear shapes) that includes curvilinear edge surfaces, including symmetrical and asymmetrical shapes. Additionally, although the first and second

major surfaces

101, 102 are depicted as planar and parallel in fig. 3A-3C, it should be understood that each of these surfaces may include one or more axes of curvature and/or may not be parallel to each other.

Referring to fig. 4A-4C, the light guide 100C may additionally be in the form of a hollow ring, including an edge surface 103, an outer wall surface 104, and an inner wall surface 104'. In the depicted embodiment, the outer wall surface 104 may serve as a light emitting surface and the edge surface 103 may serve as a light coupling surface. At least a portion of the edge surface 103 is shaped to produce an equiangular helical curvature. 4A-4C depict a symmetrical cylindrical light-directing ring 100C having a circular cross-sectional shape, it should be understood that the ring 100C may include any regular or irregular cross-sectional shape (such as circular, elliptical, triangular, square, diamond, trapezoidal, pentagonal, hexagonal, and other suitable cross-sectional shapes), including symmetrical and asymmetrical shapes having one or more linear or curvilinear edges.

Referring to fig. 5A-5C, the light guide 100D may further be in the form of a rod including an edge surface 103, an outer wall surface 104, a first end surface 106, and a second end surface 107. In the depicted embodiment, the outer wall surface 104, the first end surface 106, and/or the second end surface 107 may serve as light emitting surfaces while the edge surface 103 may serve as a light coupling surface. At least a portion of the edge surface 103 is shaped to produce an equiangular helical curvature. Although fig. 5A-5C depict a symmetrical cylindrical light guide rod 100D having a circular cross-sectional shape, it should be understood that rod 100D may include any regular or irregular cross-sectional shape, including symmetrical and asymmetrical shapes having one or more linear or curvilinear edges, such as circles, ovals, triangles, squares, diamonds, trapezoids, pentagons, hexagons, and other suitable cross-sectional shapes.

For ease of reference, referring generally to fig. 2-5, the edge surface 103 is generally drawn with a convex curvature; however, the specific nature and resulting shape of their equiangular spiral curvatures will be discussed in more detail below. Equiangular helical curvature is also discussed in U.S. provisional patent application No. 62/347,351 filed on 8.6.2016, which is hereby incorporated by reference in its entirety.

In some embodiments, the curvature of the light coupling surface (e.g., edge surface 103) of the light guide depends on the desired optical path of light emitted by the light source optically coupled to the light guide. For example, referring to FIG. 6, the curvature of the light coupling surface 105 may be designed such that light 110 emitted from a light source (e.g., LED)111 optically coupled to the light guide 100 hits the inner side 105' of the light coupling surface 105 at an angle greater than the critical angle and becomes "trapped" within the light guide due to Total Internal Reflection (TIR). As used herein, the term "optically coupled" is intended to mean that the light source is positioned relative to the light guide so as to introduce or inject light into the light source. The light source may be optically coupled to the component even if the light source is not in direct physical contact with the component. In some embodiments, the light source may be optically coupled to the at least one light coupling surface 105. According to various embodiments, for example, as depicted in FIG. 6, the light source 111 can be disposed on the first major surface 101 of the light guide 100 proximate the light coupling surface 105 or near the first major surface 101 of the light guide 100 such that light is incident on the inner side 105' of the light coupling surface 105.

Total Internal Reflection (TIR) is a phenomenon in which light propagating in a first material (e.g., glass, plastic, etc.) including a first refractive index may be totally reflected at an interface with a second material (e.g., air, etc.) including a second refractive index lower than the first refractive index. TIR can be explained using snell's law:

n₁sin(θ_i)＝n₂sin(θ_r)

which describes the refraction of light at an interface between two materials having different refractive indices. According to Snell's law, n₁Is the refractive index of the first material, n₂Is the refractive index of the second material, [ theta ]_iIs the angle (angle of incidence) of the light incident at the interface with respect to the interface normal, and Θ_rIs the angle of refraction of the refracted light relative to the normal. When the refraction angle (Θ r) is 90 °, for example, sin (Θ r) ═ 1, snell's law can be expressed as:

incident angle theta under these conditions_iAlso known as the critical angle Θ_c. The incident angle is greater than the critical angle (theta)_i>Θ_c) Will be totally internally reflected within the first material and the angle of incidence is equal to or less than the critical angle (Θ)_i≤Θ_c) Will be transmitted by the first material.

In the air (n)₁1) and glass (n)₂1.5), critical angle (Θ)_c) May be calculated to be about 42. Thus, if light propagating in the glass hits the air-glass interface at an angle of incidence greater than 42 °, all incident light will be reflected from the interface at an angle equal to the angle of incidence. If the reflected light encounters a second interface that includes the same 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 angle of incidence.

Thus, one or more edge surfaces of the light guides disclosed herein can be configured to "capture" light, e.g., such that light injected into the light coupling surface of the light guide can be repeatedly propagated within the light guide, e.g.,along the light coupling surface 105 (e.g., edge surface 103) or alternately between other surfaces of the light guide (e.g., first major surface 101, second major surface 102, inner wall surface 104, outer wall surface 104', and/or first and second end surfaces 106, 107) unless or until the interface conditions change. In some embodiments, the curvature of the light coupling surface 105 (e.g., edge surface 103) can be designed such that substantially all of the light 110 emitted from the light source 111, regardless of the origin on the light source itself, is at the angle of incidence Θ_iHit the optical coupling surface, where_i>Θ_c. For example, light 110 emitted from an upper corner of light source 111 can have a minimum angle of incidence with respect to light coupling surface 105, and thus light coupling surface 105 can be configured such that even light emitted from that location on light source 111 has an angle greater than critical angle Θ_cAngle of incidence theta_i. According to a non-limiting embodiment, at least one light coupling surface 105 (e.g., edge surface 103) of the light guide can be configured such that substantially all light from the light source 111 is at a constant angle of incidence (Θ)_i) Hit the light coupling surface 105 (e.g., edge surface 103) where Θ_i＝k>Θ_c。

The constant angle of incidence curve r (Θ) of the light coupling surface can be constructed by defining a coordinate system, with the origin defined at the upper corner of the light source. As depicted in FIG. 7, the tangent vector of the curve r (Θ) can be plotted using equation (1)

Wherein

Is a unit vector representing the direction of light, and

is and

orthogonal unit vectors.

And

the dot product of (c) can be expressed by equation (2):

wherein α isAnd

since the incident angle is the complement of α, equation (2) can be rewritten as the following equation (3):

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

the solution of equation (4) is represented by equation (5):

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

Fig. 8 depicts an exemplary constant angle of incidence curvature for a light coupling surface, where r (0) is 0.4mm and Θ_i42 deg.. The angle Θ (0) of the light emitted from the light source 111 is illustrated<Θ<π), each light resulting in an angle of incidence Θ with the edge surface_i42 deg.. Attention is paid toFor the angle theta>Pi, the constant angle of incidence curve will define a helix, also known as a logarithmic helix, an equiangular helix or a growth helix. Thus, a light coupling surface with constant incident angle curvature can include at least one region with equiangular helical curvature. In some embodiments, substantially all of the light coupling surface may have a equiangular helical curvature. In other embodiments, at least a portion of the light coupling surface may have an equiangular helical curvature (e.g., in the case of a truncated surface, as shown in fig. 9).

Curve r (theta) (0)<Θ<π) can be expressed as an angle Θ_p＝Θ_i+ π/2. The Cartesian coordinates of the peak may be represented by equations (6 a-b):

the boundary or maximum limit 116 of the convex surface to the right of the y-axis occurs at the angle Θ_iTo (3). Thus, the Cartesian coordinates of the rightmost point may be represented by equations (7 a-b):

x_rcan be used to determine the maximum radius of a light source that can be optically coupled to the edge surface.

Referring now to FIG. 9, in certain embodiments, the light coupling surface 105 of the light guide can be at least partially truncated such that the light coupling surface 105 comprises two or more portions. The first portion 105A may include a straight edge that may or may not be perpendicular to a horizontal centerline of the light guide 100, and in embodiments may form various angles with the centerline, e.g., ranging from large to largeFrom about 80 ° to about 100 °, such as from about 85 ° to about 95 °, for example about 90 °. At least a portion of the light coupling surface 105 (e.g., the second portion 105B) may have an equiangular spiral curvature. According to further embodiments, as shown in FIG. 10, the light coupling surface 105 may include more than one portion having equiangular helical curvature. For example, the second portion 105B can include one equiangular helical curvature profile, while the third portion 105C can include another equiangular helical curvature profile that is the same or different and/or has a different or the same constant angle of incidence Θ_i. Of course, additional portions having additional contours may be included, but are not limited to.

Ray tracing paths from the light source to the light guide are shown at two levels of detail in fig. 11A-11B and (enlarged) fig. 12A-12B. Fig. 11A and (enlarged) fig. 12A illustrate ray tracing paths of a light guide having a straight edge portion and two equiangular curvature profile portions, while fig. 11B and (enlarged) fig. 12B illustrate ray tracing paths of a light guide having a straight edge portion and a single equiangular curvature profile portion. Without wishing to be bound by theory, it is believed that the combination of two or more equiangular helical curvature profiles, optionally with straight edge portions, may reduce the effect of light source misalignment on optical coupling efficiency. The location of the light source relative to the light guide is critical and can affect the amount of light that leaks through the edge of the light guide. While the light source may be positioned to minimize light leakage in theory, in practice the actual positioning of the light source may include different degrees of misalignment due to several factors including, but not limited to, Printed Circuit Board (PCB) manufacturing tolerances, PCB warpage and/or PCB backplane structure, soldering the light source to the PCB. When the light source is misaligned from its ideal position, for example, if the light source extends beyond the edge of the light guide, a significant amount of light may be lost due to light leakage. Including an additional curvature profile (e.g., third portion 105C in fig. 10) may capture some of this potential light leakage and redirect it into the light guide.

FIG. 13 is a graph of light leakage of a light guide as a function of LED misalignment. The power leakage is calculated as the power coupled out through the edge of the light guide(s) divided by the sum of the power coupled out through the light emitting surface(s) and the power coupled out through the edge of the light guide(s). A positive number of misalignments indicates a misalignment towards the truncation edge of the light guide. The misalignment in fig. 13 is limited to-0.1 mm in the negative direction, since further misalignment in this direction may result in failure to meet the TIR conditions for equiangular spiral curvature profiles. Even at the ideal light source position (misalignment 0), the light leakage for the light guide with the single equiangular spiral curvature profile is 20% (curve a), while the light leakage for the light guide with the double profile is 21% (curve B). Some of the power leaks between the light source and the light guide, while the remainder leaks may be due to light exiting the edge of the light guide after multiple reflections within the light guide. When the light source is misaligned by 0.12mm, the light leakage of the single profile light guide increases from 20% to 25%. However, the same amount of misalignment does not increase light leakage of the dual-profile light guide. As shown in fig. 13, a light guide with a double profile can tolerate light source misalignments up to 0.41mm at most, resulting in an 86% misalignment tolerance improvement compared to a single profile light guide that can tolerate only 0.22mm misalignment.

Referring back to fig. 2-5, at least one light source 111 can be optically coupled to the light guides 100A-100D to form an optical assembly. For example, one or more light sources may be located near the edge surface 103. In the case of the light guide plate 100A or the light guide plate 100B, the light source may be located on the first main surface 101 near the edge surface 103 or near the first main surface 101. The cross-sectional views shown in fig. 2A, 3A, 4A and 5A show two light sources 111, one at each opposing edge surface 103. However, it should be understood that several light sources may be positioned along one or more light coupling surfaces. For example, multiple light sources may be positioned along opposing edge surfaces, as shown in fig. 2B. In other embodiments, multiple light sources may be positioned along a single light coupling surface, as shown in fig. 3B, 4B, and 5B. Alternatively, in the case of a light guide having multiple edge surfaces (such as a square or rectangular light guide), one or more light sources may be positioned along any one or more of the edge surfaces without limitation.

The size of the light guide 100 may depend on the size of the light source 111. In some embodiments, the thickness of the light guide 100 is approximately linearly proportional to the narrowest dimension of the light source 111. For example, the thickness of a light guide optically coupled to a 0.7mm by 0.7mm LED may be less than 5 mm. The thickness of the light guide may be in the range of from about 1mm to about 10mm, such as from about 2mm to about 9mm, from about 3mm to about 8mm, from about 4mm to about 7mm, or from about 5mm to about 6mm, including all ranges and subranges therebetween. In some embodiments, the light guide thickness is less than about 5mm, such as less than about 4.5mm, less than about 4mm, less than about 3.5mm, or less than about 3mm, including all ranges and subranges therebetween, e.g., from about 3mm to about 5 mm.

As shown in FIGS. 14A-B, one or more surfaces of the light guide 100 can be patterned with a color conversion medium, light scattering features, and/or reflective material. In the non-limiting embodiment shown, the first major surface 101 includes a color conversion medium 112 and a reflective layer 135. Alternatively, as discussed in more detail below, the color conversion medium 112, light scattering features, and/or reflective layer 135 may be disposed on a separate component (such as a transparent substrate) that may be included in an optical assembly that includes the light guide 100. The color conversion medium 112 may comprise at least one color conversion element, such as a phosphor, a quantum dot, and/or a luminophore, e.g. a fluorophore, and/or a luminescent polymer. The color conversion medium 112 or light scattering features can provide regions of altered interface conditions, e.g., such that reflected light incident on the color conversion medium 112 or light scattering features is at less than the critical angle Θ_cIs scattered forward. In some embodiments, the color conversion medium may serve the dual purpose of scattering incident light and converting it to a different wavelength.

As shown in more detail in fig. 6, light 110 emitted by the light source 111 may be redirected within the light guide 100 due to TIR facilitated by the curvature of the light coupling surface 105 (e.g., edge surface 103). The TIR within the light guide may be "frustrated" or interrupted in the areas where the color conversion medium 112 is distributed, such that the light 110 may escape from the light guide 100 as transmitted light 110'. The color conversion medium may also modify the light 110 such that the transmitted light 110' has a different wavelength than the original wavelength of the light 110.

The reflective layer 135 may be disposed on a major surface of the light guide 100 and may encapsulate at least a portion of the color conversion medium 112 or light scattering features (not shown). In a non-limiting embodiment, the reflective layer can include a metal film, such as a film comprising one or more of Al, Au, Ag, Pt, Pd, Cu, alloys thereof, and combinations thereof. According to various embodiments, a metal film layer, such as a silver layer covered by an aluminum layer, or the like, may also be used. In certain embodiments, the reflective layer 135 can include a material having a high thermal conductivity, e.g., capable of dissipating heat from the color conversion medium 112. Further, 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 creating cracks or pinholes. Thus, the reflective layer 135 may serve as a thermal pathway for dissipating heat from the color conversion medium 112 and/or as a hermetic barrier to prevent degradation of the color conversion medium 112 due to moisture and/or air. Other arrangements of the color conversion medium 112, light scattering features, and reflective layer 135 are discussed in more detail below. It should be understood that those embodiments may be interchanged with the embodiments shown in fig. 2-5 without limitation.

Instead of transmitting light directly through the color conversion medium ("transmissive" 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 light guide as disclosed herein comprising at least one light coupling surface having a predetermined curvature to spread the light over a larger area before the light hits the color conversion medium ("reflective" mode). In this way, the light flux within the device can be significantly reduced, for example, by up to two orders of magnitude or more. In other words, the intensity of the reflected light impinging on the color conversion medium may be less than 10% or even 1% of the intensity of the light originally transmitted from the light source. Furthermore, since light may be reflected from a reflective surface below the color conversion medium, the reflectance mode configuration may have the added benefit of passing light through the color conversion medium multiple times, thereby increasing the chance of converting light to a different wavelength.

Furthermore, the use of a "stand-off" configuration in which the color conversion medium is spaced from the light source in combination with a "reflective" mode not only reduces the luminous flux to which the medium and/or substrate is exposed, but also provides an additional heat sink path to dissipate any generated heat. Furthermore, the "remote" configuration has the additional advantage of allowing the LED to operate at cooler temperatures and thus operate more efficiently, as it does not need to be used as a thermal path for cooling the color conversion medium (e.g., as in the case of conformal phosphor coatings). Due to one or more of the above advantages, the lifetime of the optical component may be extended compared to prior art devices.

As discussed above with reference to fig. 14A, the light guide 100 can include at least one surface patterned with a color conversion medium, light scattering features, and/or reflective material. As used herein, the term "patterned" is intended to mean that the medium, features and/or materials are present on the surface of the light guide or substrate in any given pattern or design, which may be, for example, random or ordered, repeating or non-repeating, uniform or non-uniform. As discussed herein, the pattern may also include a gradient from one end of the substrate to the other.

Referring to the light guide plate 100A of fig. 2A-2C or the light guide plate 100B of fig. 3A-3C, one or both of the first major surface 101 and the second major surface 102 may be patterned with at least one of a color conversion medium, a light scattering feature, and a reflective material. In some embodiments, the second major surface 102 may be a light emitting surface, while the first major surface 101 may be patterned with a color conversion medium, light scattering features, and/or reflective material. Referring to light guide ring 100C of fig. 4A-4C, one or both of outer wall surface 104 and inner wall surface 104' may be patterned with at least one of a color conversion medium, light scattering features, and a reflective material. In various embodiments, the outer wall surface 104 may be a light emitting surface, while the inner wall surface 104' may be patterned with a color conversion medium, light scattering features, and/or reflective material. Referring to light directing bar 100D of fig. 5A-5C, outer wall surface 104 may be patterned with at least one of a color conversion medium, light scattering features, and a reflective material, and first end face 106 and/or second end face 107 may be light emitting surfaces.

In some embodiments, the reflective layer 135 may be continuous, for example, as shown in fig. 14A. Additional embodiments may also include discontinuous reflective layers 135 ', such as discontinuous reflective layer 135' illustrated in fig. 14B. Since metals (such as aluminum) may be slightly absorbing, the continuous reflective metal coating may result in a slight attenuation of the light transmitted by the light guide. As such, in some embodiments, the reflective layer may be provided only in areas corresponding to the deposits of the color conversion medium 112. Thus, region 137 may have a glass/air or plastic/air interface, allowing for greater TIR. In addition, although not shown, the portion of surface 101 corresponding to region 137 may be provided with other light scattering features, such as white scattering particles, which may be used to achieve a desired color balance of the transmitted light. While FIG. 14B illustrates a light guide 100 that includes a patterned color conversion medium 112, the configuration shown therein, as well as the configuration shown in FIG. 14A, may also be applied to a transparent substrate 130, as shown in FIG. 14C. Substrate 130 may comprise any transparent material, such as glass and plastic as disclosed herein. As shown in fig. 15, the light guide 100 can include at least one recess 150, and the transparent substrate 130 can be positioned in the recess 150 to mate or interlock with the light guide 100. The transparent substrate may include one or more functions including, but not limited to, color conversion, light scattering, light absorption, light reflection, light polarization functions, and combinations thereof.

Fig. 14C illustrates an alternative embodiment of an exemplary transparent substrate 130 including a first major surface 131 and a second major surface 132, where surface 131 is patterned with color conversion medium 112. An ink layer 138 may be disposed between the color conversion medium 112 and the reflective layer 135. The ink layer 138 may include, for example, a reflective white ink, such as a metal oxide (e.g., TiO)₂) And may be used to partially or completely block the reflective layer 135 from view. As shown in fig. 14C, an ink layer 138 may be applied along the entire first major surface 131 of the transparent substrate 130, if desired, even in areas where the color conversion medium 112 is absent. Alternatively, the ink layer 138 may be provided only in the area that includes the color conversion medium 112. And FIG. 14C illustrates a transparency including a patterned color conversion medium 112The configuration shown in the clear substrate 130 can also be applied to the light guide 100. The transparent substrate may alternatively include a major surface patterned with a color conversion medium and/or reflective material having the configuration illustrated in fig. 14A-14B.

The color conversion medium may be deposited using any method known in the art. Suitable deposition methods may include printing, such as inkjet printing, screen printing, micro-printing, and the like; coating such as spin coating, slit coating, dip coating, or the like; drop casting, pipetting, photolithography, or any combination thereof. In certain embodiments, droplets of the color conversion medium suspended in one or more solvents may be deposited on the surface of the light guide or substrate in any desired pattern. The solvent may optionally be removed by drying at ambient or elevated temperature. Similarly, the color conversion medium may include a photoresist that may be selectively removed using a photomask having a desired pattern. In some embodiments, the photoresist in which the quantum dots are suspended may also include a scattering medium for scattering blue light. Light scattering features, such as TiO, may be printed on the surface₂Particles, and/or light scattering features may be provided by etching or laser damaging a surface or below a surface.

The color conversion medium 112 and/or the light scattering features may also be sealed or encapsulated with a protective layer, such as a reflective layer 135, as shown in fig. 14A-14C. Methods of depositing the reflective layer may include, for example, sputtering or vapor deposition processes. For example, the color conversion medium 112 may be deposited on a major surface of the light guide 100 or transparent substrate 130, such as a glass or plastic substrate, and a protective metal film may then be sputtered or evaporated onto the surface to at least partially encapsulate the color conversion medium 112. In various embodiments, the light guide or substrate and the reflective layer may form a sealed container in which the color conversion medium is contained.

In further embodiments, the light guide or transparent substrate may include one or more cavities in which the color conversion medium may be deposited. The cavities may be provided, for example, by pressing, molding, cutting, or any other suitable method. According to further embodiments, the thickness of the reflective layer may be in a range of about 0.1 μm to about 10 μm, such as about 0.5 μm to about 9 μm, about 1 μm to about 8 μm, about 2 μm to about 7 μm, about 3 μm to about 6 μm, or about 4 μm to about 5 μm, including all ranges and subranges therebetween.

According to various embodiments, the color conversion medium and/or the light scattering features may be patterned on a major surface of the light guide or transparent substrate at a suitable density to produce a substantially uniform light output intensity on the light guide. An exemplary pattern is illustrated in fig. 16A, with region a of increased density and regions B-E of reduced density. In each region, each individual dot represents a discrete "island" of color conversion medium. In some embodiments, the density of the color conversion medium may be greater in region a than region B, greater in region B than region C, greater in region C than region D, and greater in region D than region E. For example, A > B > C > D > E.

In certain embodiments, the density of the color conversion medium and/or light scattering features proximate to the light source may be higher than at points further removed from the light source, or vice versa, such as a gradient from one end to the other, to properly create a desired light output distribution on the light guide. Referring again to fig. 16A, the position of the light source (not shown) is indicated by the plurality of holes 140. For example, apertures 140 may be formed to remove the color conversion medium, light scattering features, and/or reflective layer in the area of the light source so that light may be injected into the light guide without being reflected back by the reflective layer or passing directly through the area of the color conversion medium. In some embodiments, the aperture 140 may be created by a photolithographic technique to selectively remove the color conversion medium and/or reflective layer from desired areas, or to remove a portion of the substrate using mechanical means such as machining to create a void. The pattern depicted in FIG. 16A can be applied directly to the light guide or to a separate transparent substrate.

FIG. 16B illustrates another exemplary pattern of color conversion medium and reflective material. The color conversion medium 112 may be continuous or dense in an area near a light source (not shown) whose location is indicated by the aperture 140. The color conversion medium 112 may be patterned at a reduced density in areas further moved from the light source, for example, a central area as illustrated in fig. 16B. Alternatively, a continuous sheet of color conversion medium may be processed to remove the color conversion medium in desired areas to create empty voids, which may then be filled with a discontinuous reflective layer 135'. In the illustrated embodiment, a single layer may include islands of reflective layer 135' surrounded by color conversion medium 112. The pattern shown in FIG. 16B can be applied directly to the light guide or to a separate transparent substrate.

In alternative embodiments, the multilayer substrate may be included in an optical assembly, such as the configuration illustrated in fig. 16C. A continuous sheet of color conversion medium 112 (e.g., QDEF from 3M or RN16-006 from Nanoco) may be processed to remove the color conversion medium in desired areas to create empty voids 155. A separate reflective layer 135 (e.g., ESR from 3M) may then be bonded to the processed color conversion medium, optionally sandwiched between the color conversion medium and a backing sheet 160. In some embodiments, the backing plate 160 is included to provide additional mechanical support to the multi-layer sheet, or in other embodiments, the backing plate 160 is not included to reduce the overall thickness of the optical assembly. The backing plate 160 may be constructed of any of the materials disclosed herein, including glass, plastic, and metal. In some embodiments, the backing plate 160 may comprise a thermally conductive material such as a metal (e.g., aluminum, silver, copper, etc.).

Referring back to fig. 8, note that light rays reflected along regions of equiangular spiral curvature tend to travel along the top of the curve, possibly leaving a gap 115 near the light source. In this way, the light hitting the first main surface of the light source may have a non-uniform distribution, e.g. a lower light distribution close to the light source. When patterning the color conversion medium 112 and/or light scattering features on the light guide or transparent substrate, the regions of increased density can be positioned near the light sources in the regions corresponding to the gaps 115. Thus, in areas of high light distribution, which may result in excessively bright light intensity, the density of color conversion and/or light scattering islands may be reduced to increase the likelihood that light will instead hit the reflective layer and continue to be reflected within the light guide. In areas of low light distribution (such as areas near the light source), the density of color conversion and/or light scattering areas may be increased to increase the likelihood that light rays will hit the color conversion and/or light scattering areas and scatter out of the light guide.

Because the color conversion medium and/or light scattering features can be patterned to achieve substantial uniformity of transmitted light intensity, optical assemblies employing the light guides disclosed herein can be incorporated into devices (such as displays or lighting devices) without the need to provide gaps between the light guide and other components in the device that might otherwise be required to diffuse the transmitted light. Thus, even in the case of relatively thick light guides or optical assemblies including a diffusing layer, the thickness of the overall assembly may be reduced, as discussed in more detail below. In certain embodiments, the total thickness of the optical assembly may be less than about 10mm, or even less than about 5 mm.

In some embodiments, the color conversion medium 112 may include at least one color conversion element, which may be suspended in an organic or inorganic matrix, such as 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 conversion material may be deposited as a layer having a thickness of, for example, about 5 μm to about 400 μm, such as about 10 μm to about 300 μm, about 20 μm to about 200 μm, or about 50 μm to about 100 μm, including all ranges and subranges therebetween. For example, the at least one color converting element may be selected from a phosphor, a Quantum Dot (QD), and a luminophore, such as a fluorophore or a luminescent polymer. Exemplary phosphors may 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.

QDs may have different shapes and/or sizes depending on the desired wavelength of emitted light. For example, the frequency of the emitted light may increase as the size of the quantum dots decreases, e.g., the color of the emitted light may change from red to blue as the size of the quantum dots decreases. When illuminated with blue, UV, or near UV light, quantum dots can convert the light to longer red, yellow, green, or blue wavelengths. According to various embodiments, the color converting element may be selected from QDs that emit at red and green wavelengths upon irradiation with blue, UV or near UV light.

In various embodiments, the color conversion medium 112 may be made to include color conversion elements of the same or different types, e.g., elements that emit light of different wavelengths. For example, in some embodiments, the light guide 100 or transparent substrate 130 may be patterned with a mixture of color conversion elements that emit both green and red wavelengths, e.g., each individual "island" of color conversion medium may include both red and green QDs. However, according to other embodiments, a single island may comprise only color conversion elements that emit the same wavelength, such as an island comprising only green quantum dots or an island comprising only red phosphor. In a further embodiment, a single area (e.g. areas a-E in fig. 16A) may be subdivided, e.g. like spokes or pie pieces or checkerboard squares on a wheel, each other sub-area being filled with green conversion elements and its complement with red conversion elements. For example, such embodiments may be used to avoid re-conversion of light, e.g., blue to green, then green to red, or vice versa.

It is within the ability of the person skilled in the art to select the configuration of the color conversion pattern and the type and amount of color conversion medium to place in each location to achieve the desired display or lighting effect. Further, although red and green light emitting elements are discussed above, it should be understood that any type of color conversion element may be used that can emit light of any wavelength, including but not limited to red, orange, yellow, green, blue, or any other color in the visible spectrum (e.g., -420-750 nm). For example, in solid state lighting applications, quantum dots having various sizes can be combined to simulate the output of a black body, which can provide excellent color rendering. Such devices may include, for example, various types and/or sizes of color conversion elements that emit at various wavelengths, such as visible wavelengths. In some examples, combinations of color conversion elements that emit three or more different wavelengths may be used, such as four or more, five or more, or six or more different wavelengths, and so forth.

Device

The light guides and optical assemblies disclosed herein can be used in a variety of applications, including but not limited to display and lighting applications. For example, a lighting device, such as a luminaire or solid state lighting device, may include a light guide or optical assembly as disclosed herein. The light guide and optical assembly may also be incorporated into a display device, such as a backlight unit (BLU) in a television, computer, handheld device, or the like.

For example, fig. 17 illustrates a cross-sectional view of an exemplary optical assembly 200 including a light guide 100 as disclosed herein. The optical assembly further comprises a Printed Circuit Board (PCB)122 to which the one or more light sources 111 may be mounted, e.g. by soldering, to the Printed Circuit Board (PCB) 122. In some embodiments, the PCB may be attached to at least one heat sink (not shown). PCB122 may also be provided with one or more thermal vias (not shown) that may be positioned to provide a heat sink path. In some embodiments, the thermal vias may comprise apertures or holes in the PCB122 that are filled with an electrically conductive material (e.g., a metal such as Cu, Ag, etc.) that may allow for heat transfer from one side of the PCB122 to the other and into the heat sink (if present).

In some embodiments, as shown in fig. 17, an optional spacer substrate 126 including at least one cavity 128 may be used to provide a housing for the light sources 111. In other embodiments (not shown), the transparent substrate 130 may be included in an assembly and include one or more cavities that may be aligned with the PCB122 to provide a housing for the light sources 111. The spacer substrate 126 may be attached to the PCB122 using an adhesive layer 124, such as a thermally conductive tape or a silicone tape. A light source medium 134 such as silicone may be used to fill the cavities in the spacer substrate 126 (or substrate 130). However, in some embodiments, the cavity may not be filled with a medium, e.g., the cavity may contain air.

In the optical assembly 200 shown in fig. 17, the transparent substrate 130 may be patterned with a color conversion medium, light scattering features, and/or reflective material (not shown), for example, as shown in fig. 14A-14C or 16A-16C. The adhesive layer 124 may be used to attach the transparent substrate 130 to the spacer substrate 126 (if present) or the PCB 122. The light guide 100 may be similarly attached to the transparent substrate 130 using the adhesive layer 124. In certain embodiments, one or more or all of the adhesive layers 124 may comprise an optically clear adhesive. In further embodiments, one or more or all of the adhesive layers 124 may comprise a thermally conductive adhesive. In yet further embodiments, one or more or all of the adhesive layers 124 may be index matched to the light guide and/or transparent substrate, e.g., having an index of refraction that is within 5% of the index of refraction of the light guide and/or transparent substrate.

According to further embodiments, the light guide 100 may comprise plastic and the transparent substrate 130 may comprise glass. Of course, as described above, the light guide 100 can include a major surface patterned with a color conversion medium and/or light scattering features and/or reflective material (e.g., as shown in fig. 14A-14B), and in such embodiments, the transparent substrate 130 can be absent from the device. The light guide plate 100 may be aligned with respect to the PCB122 such that the light source 111 is disposed near an edge surface (not labeled) of the light guide 100.

Although not illustrated in fig. 17, the optical assembly may further include a diffusion layer, which may be included to improve uniformity of light emitted from the optical assembly. Such a diffusing layer may be included near the light emitting surface of the light guide 100, and may optionally be attached to the light guide using an additional adhesive layer 124. Exemplary diffusing layers may include, but are not limited to, polymeric sheets such as acrylic, polycarbonate, and polyethylene terephthalate sheets that may be textured, roughened, or particle-filled to produce light diffusing features (e.g., submicron-sized diffusing features) that are approximately equal to or less than the wavelength of the light to be diffused. For example, exemplary particle-filled polymer sheets can include titanium dioxide or aluminum oxide having a particle size of about 500nm or less. The textured polymeric sheet may be available from luminet^TMPurchased in the market.In certain embodiments, for example, as illustrated in fig. 14A-14C or 16A-16C, a color conversion medium, light scattering features, and/or reflective material may be disposed on a major surface of the light guide and/or transparent substrate in a pattern to produce a sufficiently uniform color and/or light intensity on the light emitting surface of the light guide. In such examples, the diffusing layer may be excluded from the optical component to further reduce the overall thickness of the component.

As discussed above, the optical assemblies disclosed herein may have improved thinness compared to prior art optical assemblies due at least in part to the lack of air gaps between the light source and the light guide. Current commercially available optical components may have an overall thickness of greater than 15 mm. In contrast, the optical assemblies disclosed herein may have an overall thickness of less than about 10 mm. For example, the thickness of an exemplary optical assembly including a diffusion layer may be less than about 10mm, while the thickness of an exemplary optical assembly without a diffusion layer may be less than about 5 mm. In some embodiments, the thickness of the optical component, with or without a diffusing layer, may be in the range of about 4mm to about 10mm, such as in the range of about 4.5mm to about 9mm, about 5mm to about 8mm, or about 6mm to about 7mm, including all ranges and subranges therebetween.

FIG. 18 illustrates a top view of an exemplary device comprising an array of light guides 100, the array of light guides 100 comprising a light coupling surface 105 optically coupled to an array of light sources 111. In the illustrated embodiment, the light sources 111 are positioned around the perimeter of each light guide 100. Although eight light sources 111 are illustrated per individual light guide 100 in the array, it should be understood that the number is arbitrary and any number of light sources may be used. The position of the light source 111 may also be different from that shown in fig. 18 as needed without limitation. The patterned color conversion medium (not shown) may be adjusted as desired to suit the number and location of the light sources 111.

As shown in the non-limiting embodiment of FIG. 19, the light source 111 may also be disposed in a more central location. In such a configuration, the light coupling surface 105 "may comprise a dome-like shape in the central region of the light guide 100, e.g., a equiangular spiral curvature may be rotated about a central axis perpendicular to the underlying light source 111 to provide the dome-like shape. The dome-shaped light coupling surface 105 "may redirect light from the light source 111 such that it is reflected back into the light guide 100 until it contacts the color conversion medium and is converted and transmitted by the light guide. Again, although four light sources 111 are illustrated per individual light guide 100 in the array, it should be understood that the number is arbitrary and that any number of light sources may be used. The position of the light source 111 may also be different from that shown in fig. 19 as needed without limitation. The patterned color conversion medium (not shown) may be adjusted as desired to suit the number and location of the light sources 111.

It will be understood that each disclosed embodiment may be directed to a particular feature, element, or step described in connection with the particular embodiment. It will also be understood that, although a particular feature, element, or step is described in connection with one particular embodiment, it may be interchanged or combined with alternate embodiments in various combinations or permutations that are not shown.

It is also to be understood that the terms "the", "a", or "an" as used herein mean "at least one" and should not be limited to "only one" unless specifically 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, "plurality" or "array" is intended to mean two or more, such that "array of cavities" or "plurality of cavities" means two or more such cavities.

Ranges may 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.

All numerical values expressed herein are to be construed as including "about" unless otherwise indicated, whether or not stated. It is further understood, however, that each value recited is also to be considered precisely, whether or not it is stated as "about" that value. Thus, "a dimension of less than 10 mm" and "a dimension of less than about 10 mm" both include embodiments of "a dimension of less than about 10 mm" and "a dimension of less than 10 mm".

Unless expressly stated otherwise, any method set forth herein is in no way to be construed as requiring that its steps be performed in a specific order. Thus, 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 not intended that any particular order be inferred.

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

It will be apparent to those skilled in the art that various modifications and variations can be made in 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.

The following examples are intended to be non-limiting and illustrative only, with the scope of the invention being limited by the claims.

Examples of the invention

Example 1

Production of a light guide plate from PMMA with a refractive index n of 1.5, having two light coupling edges with a light coupling edgeEquiangular spiral curvature (see, e.g., fig. 2A-2C), and with a constant angle of incidence Θ_i42 deg.. The light guide plate has a width of 38.5mm, a length of 45mm, and a thickness of 4.608 mm. Two optical assemblies are formed using a light guide plate, the first optical assembly being coupled to 4 LEDs and the second optical assembly being coupled to 6 LEDs. The LEDs are soldered to the PCB and powered by a gishley (Keithley) power supply at an operating current of 200 mA. The total thickness of the optical assembly was 5.3 mm.

The marine optical spectrometer is used for measuring the spectrum emitted by the optical component. A Konica Minolta colorimeter (CS 160) is used to measure the color and intensity of light emitted by the optical assembly. A digital camera with a zoom lens is used to photograph and inspect optical components. The optical radiation intensity profile of the first optical assembly (4 LEDs, 0.0039 second exposure) measured along rows and columns near the center of the light guide is depicted in fig. 20A-20B, respectively. A single experiment produced 7,400nits in the center of the light guide when illuminated by 4 LEDs operating at 100 mA. The optical radiation intensity profile of the second optical assembly (6 LEDs, 0.01013 second exposure) measured along a row near the center of the light guide is depicted in fig. 20C. An illumination area of 16.5x 45mm (43% of the total area) was created in the middle of the light guide with the light coupling edge as designed.

The first optical assembly (4 LEDs) was incorporated into a stack comprising a reflective film from Nanoco corporation and a QD film, the stack being located on the bottom surface (first major surface) of the light guide plate. A mechanical device is used to create a pattern on the QD film designed to improve the brightness and color uniformity of the light emitted from the light guide. In some cases, a diffusion film is placed on the upper surface (second major surface) of the light guide plate, thereby increasing the stack thickness to 9.7 mm. The optical radiation intensity profiles of the optical assembly (4 LEDs, 0.0039 second exposure) with the diffuser film and the unpatterned QD film, measured along rows and columns near the center of the light guide, respectively, are depicted in fig. 21A-21B. The optical radiation intensity profile of the second optical component (4 LEDs, 0.01 second exposure) with the patterned QD film but without the diffuser film, measured along a line near the center of the light guide, is depicted in fig. 21C. The optical radiation intensity profile of the second optical component (4 LEDs, 0.04 second exposure) with patterned QD film and diffuser film, measured along a line near the center of the light guide, is depicted in fig. 21D. Although stacks including diffuser films produce less radiation, possibly due to manufacturing defects, the uniformity of the intensity distribution is improved compared to stacks without these films. Furthermore, even with a diffuser film, the stack has a reduced thickness compared to current commercially available LCD stacks having a total thickness of 15mm or greater.

Example 2

The optical assembly 300 shown in fig. 22 is designed as an exemplary embodiment of an assembly having a total thickness of less than 5 mm. The light guide plate 100A (see fig. 2A to 2C) is made of PMMA having a refractive index n of 1.5. The light guide plate has a width of 50mm, a length of 60mm, and a thickness of 4.035 mm. The light coupling edge 105 is truncated (see FIG. 9) to provide a straight edge portion and has a constant angle of incidence Θ_iProfile portion of 42 °. Light L is emitted from the second main surface 102 of the light guide plate 100A.

A transparent substrate 130 is designed to include a refractive index n of 1.5. The transparent substrate has a width of 50mm, a length of 60mm and a thickness of 0.3 mm. The major surface of the transparent substrate is patterned with QDs (e.g., QDEF from 3M) using a masking technique to provide an array of voids (1.9 mm in diameter and 2mm apart) that can be filled with a reflective material (e.g., silver or aluminum) (see fig. 16B).

Four light sources 111 (blue LEDs from Flip Chip Opto-electronic (Flip Chip Opto), 450nm, >0.42W,0.5A) were attached to an FR4 PCB122 with a thickness of 0.508 mm. The length and width of the LED was 0.875mm and the thickness 0.145 mm. The spatial distribution of the LEDs is almost Lambertian. The current C may be applied to circuitry of the PCB122 to control the light output of the LED. LEDs are capable of producing optical power outputs of up to 1W at higher diode currents. Heat H from the LED and/or the color conversion medium may be conducted away through a metal layer on the bottom surface of the PCB122 (not shown). The PCB122 is equipped with metal lines and pads for connection to the LEDs and thermal vias for transporting heat from the top surface to the bottom surface of the PCB.

An index matching optically clear adhesive layer 124A (silicone adhesive from dow corning, n ═ 1.5) having a thickness of 0.025mm was used to attach light guide plate 100A to transparent substrate 130. Thermally conductive adhesive 124B from dow corning is used to attach transparent substrate 130 to PCB 122. A hole 140 corresponding to the light source 111 is provided in each of the

adhesive layers

124A, 124B and the transparent substrate 130. The spacing between the holes 140 is 25mm and the holes are spaced 12.5mm from the edge of the substrate. The total thickness of the optical assembly was 4.92 mm. Thinner assemblies can be achieved, for example, by using smaller LEDs, such as lumen (Lumileds) diodes (455nm, >0.65W, 0.5A), by patterning the color conversion medium and reflective material directly onto the light guide, and/or using a higher index of refraction light guide, such as n > 1.7.

Example 3

The optical assembly 300 described in example 2 was analyzed with Lighttools fiber optic propagation software using the following assumptions: (1) the space between the top surface of the LED and the bottom surface of the light guide is filled with an index matching layer; (2) the refractive index of the light guide, the transparent substrate and the refractive index matching layer is n-1.5; (3) a top surface of the transparent substrate is optically coupled to a bottom surface of the light guide; (4) the quantum dots on the transparent substrate form a simple scattering surface with lambertian scattering properties; (5) the reflecting layer has a broadband mirror surface; (6) all other surfaces are high quality optical surfaces; and (7) all light guide surfaces except the bottom surface (second major surface) of the light guide are assumed to be in contact with air. The LED surface is set as the illumination surface and the receiver is placed on a light output plane parallel to and just outside the first main (light emitting) surface of the light guide. Lighttools are used to calculate the illumination characteristics at the light output plane.

An optical assembly comprising a glass substrate uniformly coated with QDs was used as a baseline calculation. Output irradiance profile (W/mm) of such optical assemblies²) Shown in fig. 23A. The irradiance profile shows four regions of high intensity corresponding to four LEDs. Irradiance uniformity, measured by the ratio of standard deviation to mean, was 41%. Without wishing to be bound by theory, it is believed that the uniformity of irradiation of the optical component may be improved by including a diffusing layer in the optical componentAlthough such layers will increase the overall thickness of the device. However, even with such a diffusing layer, the overall thickness of the assembly can still be less than 10mm, which is an improvement over currently available assemblies having a thickness greater than 15 mm.

The optical assembly 300 including the patterned transparent substrate 130 prepared in example 2 was similarly tested using Lighttools software. Output irradiance profile (W/mm)²) Shown in fig. 23B. The irradiance profile is more uniform than the baseline profile shown in fig. 23A. Irradiance uniformity, measured by the ratio of standard deviation to mean, was 18.5%, which is a significant improvement over the baseline assembly and currently available assemblies.

For a total input power of 4W from the LEDs, a brightness measured at the light output plane of greater than 50,000nits was calculated. Brightness can be increased by adding more LEDs along the light coupling surface, if desired. Assuming that the QDs are scattering layers without color conversion, 61% of the LED power is emitted at the light output plane, 29% of the LED power is emitted at the light coupling edge (width 50mm), and 10% of the LED power is emitted at the non-light coupling edge (length 60 mm). Without wishing to be bound by theory, it is believed that more power can be made available to the light output plane by applying a reflective coating on the non-light coupling edge.

Claims

1. A light guide, comprising:

at least one light emitting surface and at least one light coupling surface, wherein at least a portion of the at least one light coupling surface comprises a equiangular spiral curvature.

2. The light guide of claim 1, wherein the light guide comprises a light guide plate comprising:

a first major surface;

an opposing second major surface; and

at least one edge surface;

wherein the at least one edge surface comprises the light coupling surface.

3. The light guide of claim 1, wherein the light guide comprises a light guide disk comprising:

a first major surface;

an opposing second major surface; and

an edge surface;

wherein the edge surface comprises the light coupling surface.

4. A light guide as claimed in claim 2 or 3, wherein the second major surface comprises the light emitting surface.

5. The light guide of claim 4, further comprising at least one of a color conversion medium, a light scattering feature, and a reflective material patterned on the first major surface.

6. The light guide of claim 4, wherein a reflective layer is disposed on the first major surface and at least partially encapsulates a color conversion medium patterned on the first major surface.

7. The light guide of claim 1, wherein the light guide comprises a light guide ring comprising:

an inner wall surface;

an outer wall surface; and

at least one edge surface;

wherein the at least one edge surface comprises the light coupling surface.

8. The light guide of claim 7, wherein the outer wall surface comprises the light emitting surface.

9. The light guide of claim 7, wherein the light guide ring comprises a hollow cylinder.

10. The light guide of claim 1, wherein the light guide comprises a light guide rod comprising:

a first end face;

a second end face;

an outer wall surface; and

an edge surface;

wherein the edge surface comprises the light coupling surface.

11. The light guide of claim 10, wherein at least one of the first end face, the second end face, and the outer wall surface comprises a light emitting surface.

12. An optical assembly comprising at least one light source optically coupled to the light guide of any one of claims 1-11.

13. The optical assembly of claim 12, wherein the at least one light source is bonded to a printed circuit board.

14. The optical assembly of claim 12 or 13, further comprising a transparent substrate including a major surface patterned with at least one of a color conversion medium, a light scattering feature, and a reflective material.

15. The optical assembly of claim 13, wherein a color conversion medium is patterned on the major surface and a reflective layer at least partially encapsulates the color conversion medium.

16. The optical assembly of any one of claims 12-15, further comprising a diffusing layer located adjacent to at least one light emitting surface of the light guide.

17. The optical assembly of any one of claims 12-16, wherein the optical assembly comprises a stack having a total thickness of less than about 10 mm.

18. The optical assembly of claim 17, wherein the total thickness of the stack is less than about 5 mm.

19. The optical assembly of claim 12, wherein the light guide and transparent substrate comprise glass, plastic, or a combination thereof.

20. A display device, a lighting device, or an electronic device comprising the optical assembly of any one of claims 12-19.

21. The apparatus of claim 20, wherein the apparatus comprises an array of optical components.