Patent Application
20170167697
Aspects of this invention relate generally to a housing for use with a color converting material assembly and, in particular, a housing used to hold a color converting material assembly that includes a chamber containing a color converting material.
Backlights are used for illumination in liquid crystal displays (LCDs) and may use light emitting diodes (LEDs) as the light source. The light from an LED may be projected through a lens and a diffuser, and then on to the LCD. Standard backlights utilize a white LED in the light generating portion of the backlight. The white LED is typically an assembly including a light emitting semiconductor die emitting at higher frequency (e.g., ultraviolet or blue) together with a phosphor or combination of phosphors that converts some portion of the higher frequency light to lower frequency visible light (e.g., green and red). The combination of higher frequency and lower frequency light generates white light. The phosphors used for color conversion in white LEDs are typically a phosphor or combination of phosphors with a broad spectral bandwidth.
In certain embodiments described herein, the light generating portion of the backlight utilizes one or more discrete LEDs emitting at higher frequencies (e.g., ultraviolet or blue) that excite a remotely located color converting material containing color converting elements, such as quantum dots (semiconductor nanocrystals), which convert some portion of the higher frequency light to lower frequency visible light (e.g., green and red). The combination of the higher frequency light passing through and/or around the outside of the color converting material and the shorter frequency light emitted by the color converting material gives white light. The narrow spectral bandwidth of the emission peaks of the quantum dots enables higher efficiency and/or wider color gamut backlights as compared with the standard white LED solution. One way to introduce quantum dots (QDs) or other color converting elements into a backlight unit (BLU) is to place them in a glass chamber, between the higher frequency LED illumination and the lens. However, light that passes from the LED through the color converting material to the lens may be multiply scattered and reflected, leading to a loss of efficiency and distortion of the backlight color uniformity. An appropriate mount for the chamber holding the color converting material that is positioned between the LED and the diffuser can be designed to improve efficiency and color uniformity or provide a desired balance between efficiency and color uniformity. The principles of the invention may be used to provide a housing for a chamber containing a color converting material that can be used in a backlight with LEDs.
In accordance with a first aspect, a mount for a color converting assembly includes a housing having a first pair of opposed walls and a second pair of opposed walls. The housing has a first opening at a first end thereof and a second opening at a second end thereof. A shelf extends inwardly from each of the walls at a point below the second end of the housing such that each wall extends upwardly beyond the shelf to the second end of the housing. The walls and shelf are formed of a reflective material.
In accordance with another aspect, an assembly includes a housing having a first pair of opposed walls and a second pair of opposed walls, with the housing having a first opening at a first end thereof and a second opening at a second end thereof. A shelf extends inwardly from each of the walls at a point below the second end of the housing such that each wall extends upwardly beyond the shelf to the second end of the housing. A color converting assembly is seated on the shelf and includes a chamber having a cavity formed therein. A color converting material is received in the chamber.
In accordance with a further aspect, an assembly includes a PCB, an LED secured to the PCB, and a housing having a first end secured to the PCB. The housing includes a first pair of opposed walls and a second pair of opposed walls, with the housing having a first opening at the first end and a second opening at a second end thereof. The LED extends upwardly into the first opening. A shelf extends inwardly from each of the walls at a point below the second end of the housing such that each wall extends upwardly beyond the shelf to the second end of the housing. A color converting assembly is seated on the shelf and includes a chamber having a cavity formed therein. A color converting material is received in the chamber. The assembly can further include a lens positioned at the second end of the housing. Alternatively, a lens can be positioned above the housing. An assembly can further include an LCD positioned above the diffuser. Preferably a first diffuser can be positioned between the lens and the LCD.
The use of a housing for a color converting material assembly can provide higher efficiency and/or wider color gamut backlights than are possible with standard white LED solutions. The housing for the color converting material chamber as described herein can improve efficiency and color uniformity or provide a desired balance between efficiency and color uniformity. These and additional features and advantages disclosed here will be further understood from the following detailed disclosure of certain embodiments.
In accordance with a still further aspect, an assembly includes a PCB, an LED secured to the PCB; and a housing having a first end secured to the PCB. The housing includes a first pair of opposed walls and a second pair of opposed walls, the housing having a first opening at the first end and a second opening at a second end thereof. The LED extends upwardly into the first opening. A shelf extends inwardly from each of the walls at a point below the second end of the housing such that each wall extends upwardly beyond the shelf to the second end of the housing.
It should be appreciated by those persons having ordinary skill in the art(s) to which the present invention relates that any of the features described herein in respect of any particular aspect and/or embodiment of the present invention can be combined with one or more of any of the other features of any other aspects and/or embodiments of the present invention described herein, with modifications as appropriate to ensure compatibility of the combinations. Such combinations are considered to be part of the present invention contemplated by this disclosure.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.
The figures referred to above are not drawn necessarily to scale, should be understood to provide a representation of particular embodiments of the invention, and are merely conceptual in nature and illustrative of the principles involved. Some features of the housing and color converting assembly depicted in the drawings have been enlarged or distorted relative to others to facilitate explanation and understanding. The same reference numbers are used in the drawings for similar or identical components and features shown in various alternative embodiments. Housings for use with a color converting material assembly as disclosed herein would have configurations and components determined, in part, by the intended application and environment in which they are used.
The following discussion and accompanying figures disclose a housing for use with a color converting material assembly in conjunction with an LED in a backlight. Such a housing and color converting material assembly may be used in a direct lit TV, for example.
An individual skilled in the relevant art will appreciate, given the benefit of this specification, that the concepts disclosed herein with regard to the mount may apply to a wide variety of light applications, in addition to the specific embodiments discussed in the following material and depicted in the accompanying figures.
A housing 10 for use in a backlight 12 is depicted in
It is to be appreciated that housing 10 can be used with a variety of LEDs including, but not limited to, surface mount, dome type, flat top side emitting diodes, and top face emitters. LEDs included in a backlight unit can be selected to emit light with a predetermined peak emission wavelength. For example, LEDs included in a backlight unit can be selected to emit light with a wavelength in the visible or ultraviolet regions of the electromagnetic spectrum. LEDs that emit polychromatic light can also be included. If more than one LED is included, each LED can be selected to emit light with a peak emission that is the same as that of the other LEDs. Alternatively, if more than one LED is included, the LEDs can be selected so that one or more of the LEDs emit light with a peak emission at a wavelength that is different from that emitted by at least one of the other LEDS. In certain embodiments, for example, all of the LEDs can be selected to emit light with a peak emission in the blue region of the visible spectrum or in the ultraviolet region of the spectrum.
Housing 10 receives a color converting assembly 18, and a lens 20 is positioned downstream of housing 10. In certain embodiments, lens 20 is directly in contact with housing 10, while in other embodiments, lens 20 may be spaced from housing 10.
It is to be appreciated that in certain embodiments, lens 20 can be replaced with another transmissive optical device. For example, diffractive elements that use interference and diffraction may be used in place of lens 20. In other embodiments, mirrors could be used in place of lens 20. Other suitable replacements for lens 20 will become readily apparent to those skilled in the art, given the benefit of this disclosure.
Light is transmitted from LED 14 through color converting assembly 18 and lens 20 and then to a first diffuser 22. First diffuser 22 serves to help more evenly distribute the light transmitted from LED 14.
One or more layers of a brightness enhancing film (“BEF”) 24 may be positioned downstream of first diffuser 22, and serve to increase the brightness of the backlight. In the illustrated embodiment, first and second BEFs 24 are shown. BEF 24 may be formed of a sheet of polymer material imprinted with a prismatic surface pattern. BEF 24 serves to help direct the light from the LED, thereby increasing the brightness of the light received by the user. A second diffuser 26 may be positioned downstream of BEF layers 24, with an LCD 28 positioned downstream of second diffuser 26.
As illustrated in
A shelf 42 extends inwardly from each of first walls 30 and second walls 32 about a periphery of an interior of housing 10. Shelf 42 is positioned beneath second end 40 of housing 10 such that a portion of each of first walls 30 and a portion of each of second walls 32 extends upwardly beyond shelf 42 to second end 40. Shelf 42 serves to provide support for color converting assembly 18.
Color converting assembly 18 may include a chamber 44 having a cavity 46 formed therein. A color converting material 48 is received in cavity 46. In certain embodiments, chamber 44 may be formed of an upper or first portion 50 and a lower or second portion 52. In the illustrated embodiment, cavity 46 is formed in a bottom surface of first portion 50, and second portion 52 is secured to first portion 50, covering cavity 46 and color converting material 48 contained therein. In certain embodiments, as illustrated in
Chamber 44 may be formed of glass or any other optically clear solid material member. An optically clear solid material has low optical absorption over the spectral range of interest (i.e. the visible) to maximize efficiency. In certain embodiments, the optical absorption may be less than 0.1% per mm.
The color converting material 48 could include one or more color converting elements such as, for example, quantum dots, phosphors, or fluorescent material. It is to be appreciated that color converting material 48 may contain a single color converting element or any combination of multiple color converting elements. Other suitable color converting elements suitable for use in color converting material 48 will become readily apparent to those skilled in the art, given the benefit of this disclosure.
Preferred color converting materials include quantum dots that emit light with a full width less than or equal to 35 nm. A color converting material preferably further comprises an optically transparent or clear matrix in which the color converting component is dispersed or distributed. A color converting material can further include one or more additional additives. Examples of such additives include, without limitation, scatterers or scattering particles, a thixotrope, and an emission stabilizer. Descriptions of exemplary optical materials suitable for use as or inclusion in a color converting materials and exemplary components suitable for inclusion therein are disclosed in U.S. patent application Ser. No. 14/284,277 filed 21 May 2014 of Nick, et al. and WO 2014/018090 of QD Vision, Inc., published 30 Jan. 2014, each of which is hereby incorporated herein by reference in its entirety.
In certain embodiments, it is desirable for color converting assembly 18 to have very low permeability to oxygen to extend the lifetime of quantum dots contained within color converting material 48. In certain embodiments, the permeability is less than approximately 0.01 cc per square meter per day. Most preferably, the color converting assembly is hermetically sealed.
The higher frequency light emitted from the LED may have a narrower angular distribution than the lower frequency light emitted from the color converting material. The difference in angular distribution between lower frequency and higher frequency light may increase BLU color nonuniformity. To better match the angular profiles between higher and lower frequency light, and achieve a more uniform angular emission pattern light, light scattering particles, or scatterers 55, may be added to color converting material 48 to achieve a more uniform angular emission pattern. The scatterers are sub-wavelength size particles with refractive index significantly higher than that of the matrix and are often composed of titanium dioxide, zinc oxide, antimony oxide, or mixtures thereof.
With scatterers 55, the light that would otherwise pass through color converting material 48 is diffusely reflected. Some portion of the diffusely reflected light enters color converting material 48 where it is scattered and/or converted by the color converting elements. Scatterers 55 inside color converting material 48 provide better color uniformity and also enable the use of lower color converting element concentrations. It is to be appreciated that there is a tradeoff between improved color uniformity and lower efficiency due to the scattering process. Scatterers 55 may be formed of sub-wavelength size particles with significantly higher index of refraction than that of the matrix material, such as titanium dioxide, zinc oxide, antimony oxide, or suitable combinations. Other suitable materials for scatterers 55 will become readily apparent to those skilled in the art, given the benefit of this disclosure.
Light interacting with scatterers 55 will be scattered within a specific range of directions according to the size and index of refraction of the particles. If the scattering profile is sufficiently widely distributed in angle, the higher frequency light will derive a wider angular profile that may better match the angular emission profile of the color converting element. However, in this case, more higher frequency light will scatter away from the forward direction and interact with peripheral absorbing structures such as the LEDs and holder, and the efficiency will be lower. Thus, an appropriate scatterer may be used as a lever to balance efficiency and color uniformity.
Descriptions of exemplary color converting assemblies are disclosed in WO2014/085424, entitled “LED Lighting Devices With Quantum Dot Glass Containment Plates,” and WO2015/0159894, entitled “LED Lighting Devices,” the disclosures of each of which are incorporated by reference herein in their entirety.
Housing 10 operates to maintain color converting material 48 at a desired location with respect to LED 14. Housing 10 can also operate to maintain color converting material 48 at a desired location with respect to lens 20 (if included), and to redirect light that would otherwise not be injected into lens 20 into a more efficient direction. Housing 10 may also serve to direct more higher frequency light from LED 14 into color converting material 48 to improve backlight efficiency.
Housing 10 may also dissipate heat produced by LED 14 and color converting material 48.
Housing 10 may be electrically insulating, high in diffuse or specular bulk reflectivity (typically greater than 95% across the visible range), thermally conductive, and may be formed of a material able to withstand temperatures of up to 105° C. and fluxes of up to 1 W/cm2 without any significant degradation of reflective properties across visible wavelengths or mechanical and structural integrity. If uncoated, housing 10 must have sufficient thickness to maintain bulk reflectivity, and may have any machined, printed, or molded surface finish that maintains a high reflectivity. Housing 10 may be coated with a white reflective paint or other coating such as Star-Brite White EF (available from SPRAYLAT Sign Coatings) or a barium sulfate based white paint, thermal sprays that include ceramic(s), polymer sprays that include Teflon PTFE, or specularly reflective coatings such as Aluminum or Silver.
Housing 10 may be formed of a plastic or polymer. For example, housing 10 may be formed of, or coated with, polycarbonate or polytetrafluoroethylene. Housing 10 may also be formed of metal, such as aluminum, tin, zinc, magnesium, or an alloy including at least one of the foregoing. Housing 12 can also be formed of other materials such as Makrolon® by Bayer, Lexan® by GE, OP.DI.MA. by Gigahertz-Optik, polyethylene terephthalate (PET), micro cell polyethylene terephthalate (MCPET), GORE® Diffuse Reflector Product, Idemitsu URC2501, and Delrin® and Teflon by Dupont, for example. Other suitable materials for housing 10 will become readily apparent to those skilled in the art, given the benefit of this disclosure.
Housing 10 may be formed by machining, stamping, extrusion, molding, 3D printing, or casting, for example. Other suitable ways of forming housing 10 will become readily apparent to those skilled in the art, given the benefit of this disclosure.
As illustrated in
Additionally, by positioning shelf 42 such that that a portion of each of first walls 30 and second walls 32 extends upwardly beyond shelf 42 to second end 40, housing 10 redirects light that may escape from edges of chamber 44 back into glass chamber 44. This redirection of light serves to eliminate an unwanted shift of the front-of-screen color point and possible non-uniformity of the LCD screen.
In certain embodiments, housing 10 may include one or more fasteners to secure color converting assembly 18 to housing 10. For example, as seen in
In certain embodiments, as illustrated in
In certain embodiments, housing 10 is secured to PCB 16 with glue, epoxy, or any of various other adhesives. In other embodiments, housing 10 may be secured to PCB 16 with a fastener. As seen in
In other embodiments, one or more fasteners may be formed on PCB 16 in order to retain housing 10. For example, as seen in
In other embodiments, as seen in
In further embodiments, as seen in
It is to be appreciated that there are numerous types of fasteners, and locations for the fasteners, that can be used to accurately place and secured housing 10 on PCB 16. Other suitable fasteners, and locations, will become readily apparent to those skilled in the art, given the benefit of this disclosure.
In certain embodiments, as illustrated in
Thus, while there have been shown, described, and pointed out fundamental novel features of various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the housing and color converting assembly illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. For example, it is expressly intended that all combinations of those elements and/or steps which perform substantially the same function, in substantially the same way, to achieve the same results are within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated.
Applicant specifically incorporates the entire contents of all cited references (e.g., papers, patent documents, patent publications, etc.) in this disclosure. Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range, or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range.
Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the present specification and practice of the present invention disclosed herein. It is intended that the present specification and examples be considered as exemplary only with a true scope and spirit of the invention being indicated by the following claims and equivalents thereof.
This application claims priority to U.S. Provisional Patent Application No. 62/267,001 filed 14 Dec. 2015, which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62267001 | Dec 2015 | US |
