Method and apparatus for light diffusion
10157896 ยท 2018-12-18
Assignee
Inventors
- Cody Peterson (Hayden, ID, US)
- Andrew Huska (Liberty Lake, WA, US)
- Monica Hansen (Santa Barbara, CA, US)
- Clinton Adams (Coeur d' Alene, ID, US)
Cpc classification
G02F1/133606
PHYSICS
H01L33/62
ELECTRICITY
H01L21/4853
ELECTRICITY
H01L2223/54433
ELECTRICITY
H01L2924/00014
ELECTRICITY
H01L2221/68381
ELECTRICITY
H01L24/75
ELECTRICITY
H01L2224/16238
ELECTRICITY
H01L21/68742
ELECTRICITY
H01L2224/81191
ELECTRICITY
H01L2223/54413
ELECTRICITY
H01L21/67144
ELECTRICITY
H01L2924/00014
ELECTRICITY
H01L21/67196
ELECTRICITY
H01L2933/0066
ELECTRICITY
H01L24/89
ELECTRICITY
H01L21/67265
ELECTRICITY
H01L2221/68363
ELECTRICITY
H01L22/20
ELECTRICITY
H01L2223/54486
ELECTRICITY
H01L2224/75252
ELECTRICITY
H01L22/12
ELECTRICITY
H01L2224/75262
ELECTRICITY
H01L23/544
ELECTRICITY
H01L21/67132
ELECTRICITY
H01L2221/68322
ELECTRICITY
International classification
G09F13/04
PHYSICS
H01L33/62
ELECTRICITY
H01L21/67
ELECTRICITY
H01L23/544
ELECTRICITY
G02F1/1335
PHYSICS
H01L21/687
ELECTRICITY
H01L25/075
ELECTRICITY
H01L21/48
ELECTRICITY
Abstract
A display apparatus includes a substrate and a plurality of LEDs. Each LED is attached to the substrate via conductive pads on a side of the LED. A diffuser having light diffusing characteristics is aligned with the plurality LEDs against a surface of the substrate. The diffuser is aligned so as to nest around at least one LED of the plurality of LEDs.
Claims
1. A display apparatus comprising: a substrate; a plurality of LEDs, each LED each LED being attached to the substrate via conductive pads on a side of the LED; and a diffuser having light diffusing characteristics aligned with the plurality LEDs against a surface of the substrate, the diffuser aligned so as to nest around at least one LED of the plurality of LEDs, and the at least one LED being optically coupled to the diffuser, wherein an average thickness of the diffuser is less than a height of the at least one LED.
2. The display apparatus according to claim 1, wherein the plurality of LEDs includes a first LED and a second LED spaced apart from each other on the substrate, and wherein a portion of the substrate between the first LED and the second LED includes a reflective surface so as to reflect light in a direction away from the substrate.
3. The display apparatus according to claim 1, wherein the plurality of LEDs includes a first LED and a second LED spaced apart from each other on the substrate.
4. The display apparatus according to claim 1, wherein the material of the diffuser includes at least one of silicone, polycarbonate (PC), or polyethylene terephthalate (PET).
5. The display according to claim 1, wherein the diffuser is formed of a moldable polymer film.
6. The display apparatus according to claim 1, further comprising a conductive trace disposed on the substrate and connected to the conductive pads of each LED of the plurality of LEDs.
7. The display apparatus according to claim 1, wherein the substrate is a printed circuit board (PCB).
8. The display apparatus according to claim 1, wherein the at least one LED is optically coupled to the diffuser via at least one of phosphor or silicone.
9. An apparatus comprising: a diffuser substrate; and an array of LEDs aligned with the diffuser substrate so as to nest within the diffuser substrate, the array of LEDs being optically coupled to the diffuser substrate, wherein an average thickness dimension of the diffuser substrate is less than a height of the array of LEDs.
10. The apparatus according to claim 9, further comprising a circuit substrate attached to the LEDs.
11. The apparatus according to claim 10, wherein the diffuser substrate includes texture features.
12. The apparatus according to claim 9, wherein a surface of the diffuser substrate includes texture features extending circumferentially around at least one LED of the array of LEDs.
13. The apparatus according to claim 12, wherein a size of a largest dimension of a particular texture feature depends on a radial distance between the at least one LED and the particular texture feature.
14. The apparatus according to claim 12, wherein a largest dimension of a first particular texture feature disposed a first radial distance away from the at least one LED is less than a largest dimension of a second particular texture feature disposed a second radial distance away from the at least one LED, the first radial distance being shorter than the second radial distance.
15. The apparatus according to claim 9, wherein a surface of the diffuser substrate includes texture features extending circumferentially around each LED of the array of LEDs, and wherein a size of each texture feature depends on a radial distance from one or more LEDs.
16. The apparatus according to claim 15, wherein a depth and/or a breadth of a particular texture feature disposed halfway across a distance between two adjacent LEDs is greater than a corresponding depth and/or breadth of a texture feature located less than the distance that is halfway between the two adjacent LEDs.
17. The apparatus according to claim 9, wherein one or more LEDs of the array of LEDs are optically coupled to the diffuser substrate via at least one of phosphor or silicone.
18. An apparatus comprising: a circuit substrate; a display panel disposed substantially parallel to the circuit substrate; a diffuser substrate disposed between the circuit substrate and the display panel; and an array of LEDs in columns and rows nested across a plane of the diffuser substrate so as to be aligned with the diffuser substrate and attached to the circuit substrate, each LED being attached to the circuit substrate via conductive pads on a side of the LED, and each LED being optically coupled to the diffuser substrate, wherein the diffuser substrate includes texture features extending circumferentially around one or more LEDs of the array of LEDs, and wherein an average thickness of the diffuser substrate is less than a height of the array of LEDs.
19. The apparatus according to claim 18, wherein each LED is optically coupled to the diffuser substrate via at least one of phosphor or silicone.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The Detailed Description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. Furthermore, the drawings may be considered as providing an approximate depiction of the relative sizes of the individual components within individual figures. However, the drawings are not to scale, and the relative sizes of the individual components, both within individual figures and between the different figures, may vary from what is depicted. In particular, some of the figures may depict components as a certain size or shape, while other figures may depict the same components on a larger scale or differently shaped for the sake of clarity.
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DETAILED DESCRIPTION
(12) Overview
(13) This disclosure is directed generally to a method and apparatus for effective and consistent diffusion of light across the plane of the display surface, for example, of a device having an LCD. For example, the instant application provides a description of a method and apparatus with respect to a nested diffuser. The features described herein of the nested diffuser increase diffusion of light (in comparison to previous methods) while minimizing the number of light sources used to provide a uniform light distribution across the display surface to thereby reduce the cost of manufacturing, and/or minimize a thickness of the display. The term nested diffuser is used herein to describe the feature that light diffusion occurs within the same layer of the LCD in which the light is diffused, i.e., within the diffuser at approximately the height/thickness of the light source. In other words, the light sources may be disposed or nested within the layer of the LCD that is providing the light diffusion. Hence, the nested diffuser. By disposing the light sources directly within the layer of light diffusion, an overall thickness of the LCD may be reduced.
(14) Furthermore, a thickness of a device on which the method or apparatus of the instant application is applied may be reduced due, at least in part, to the micro size of the light sources used and the manner of light diffusion. In particular, a thickness of the diffuser may be reduced to approximately the height of the light source. In some instances, the light sources may be selected from packaged or unpackaged LEDs. The use of unpackaged LEDs increases the ability to make a thinner display compared to a display using packaged LEDs.
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(16) In this conventional configuration, when the LED 102 is attached to a substrate (not shown) having a circuit by which LED 102 is powered to emit light, the light emission pattern 104 of
(17) Illustrative Embodiments of an LED and Nested Diffuser for Uniform Light Diffusion
(18) According to an embodiment of the instant application,
(19) In an illustrative embodiment, the apparatus 200 may include a substrate 202 and multiple LEDs (e.g., LEDs 204A, 204B) secured to substrate 202. Note that, in some instances, there may be only one LED. The LEDs 204A, 204B may be standard LEDs having electrical contacts on a top side or may be flip chips having electrical contacts on the bottom side. The substrate 202 includes the circuit traces (shown and discussed in greater detail later) via which the LEDs 204A, 204B are attached to the substrate 202 and powered. Thus, the substrate 202 may be a circuit board, such as a printed circuit board (PCB). Moreover, the substrate 202 may be formed from a polymer as a thin film having a thickness approximately the same as a height of LEDs 204A, 204B. Suitable materials for the substrate 202 include materials, such as PET, which are capable of maintaining structural integrity despite potential temperature changes due to the current flow in one or more LEDs.
(20) The LEDs mounted to the substrate 202 may respectively have different structural configurations depending on technological needs, or all of the LEDs may have similar structural configurations. As depicted, and discussed with respect to LED 204A (LED 204B shows a similar configuration), LED 204A includes a first reflective element 206A and a second reflective element 206B. The first reflective element 206A may be formed on a side of the LED 204A, opposite a side of the LED 204A that is attached to the substrate 202, so as to reflect light toward the substrate. The second reflective element 206B may be formed on the side of the LED 204A that is attached to the substrate 202.
(21) Furthermore, first reflective element 206A and second reflective element 206B may be mirrored surfaces. In some instances, first reflective element 206A and second reflective element 206B are formed by metal mirror contacts. Aluminum (Al) and silver (Ag) are the highest reflectivity metals for a blue LED wavelength range. An omnidirectional reflective element may be made from a stack of dielectric materials with different indicies of refraction. These dielectric materials can include TiO.sub.2, SiO.sub.2, HfO.sub.2, Ta.sub.2O.sub.5, etc. Additionally, and/or alternatively, a white diffuse polymer-based reflective element material (which may be spun fibers with some TiO.sub.2-like particles embedded) may be used. Note that first reflective element 206A and second reflective element 206B may be formed from the same material or different materials. That is, first reflective element 206A may be formed from a first material and second reflective element 206B may be formed from a second material that is different than the first material (e.g., first reflective element 206A may be aluminum and second reflective element 206B may be silver, or vice versa).
(22) Inasmuch as the design and structure of the LEDs described above is useful in directing emitted light, the LEDs 204A, 204B may be implemented as the LEDs in an edge-lit LCD to focus the light emissions into the light guide plate from the edge (not shown), as well as being nested in the diffuser as described herein.
(23) In some instances, the multiple LEDs 204A, 204B may be placed on the substrate 202 first and a diffuser 208 may be aligned with the multiple LEDs 204A, 204B so as to nest the multiple LEDs 204A, 204B within the diffuser 208. Alternatively, the multiple LEDs 204A, 204B may be nested directly in the diffuser 208, which is then aligned with the circuitry on substrate 202. As depicted, a display panel 209 of glass, plastic, or other suitable transparent or translucent material may be placed on a side of the LEDs and diffuser 208 opposite the substrate 202 so as to sandwich the multiple LEDs 204A, 204B and diffuser 208 therebetween. The diffuser 208 acts as a light guide or diffuser plate to assist in uniformly distributing the light emitted by the multiple LEDs 204A, 204B across the display panel 209. The material of the diffuser 208 may include silicone, polycarbonate (PC), polyethylene terephthalate (PET), glass, etc. Furthermore, the diffuser 208 may be a thin, moldable polymer sheet.
(24) In some instances, a third reflective element 210 may be disposed or coated, as shown, either on a surface of the substrate 202 to at least partially cover an area of the surface of substrate 202 between adjacent LEDs (between 204A and 204B) or on a surface of the diffuser 208. The material of the third reflective element 210 may be formed of a reflective material, such as those discussed above with respect to first reflective element 206A and second reflective element 206B, including aluminum, silver, etc. The material of the third reflective element 210 assists in minimizing light absorption or otherwise minimizes emitted light from being negatively affected by the substrate 202, such as passing through substrate 202 between adjacent LEDs in the diffuser 208. In some instances, substrate 202 may be formed of a material that is inherently reflective. Alternatively, there may be no need for a third reflective element, as it may be undesirable for a particular technological purpose. For example, it may be desirable that substrate 202 is transparent or translucent to allow some light emissions through the substrate 202.
(25) A cross-sectional close-up view 212 of LED 204B depicts the reflectivity of light emissions 214, indicating that light emissions 214 may be reflected back and forth between the first reflective element and the second reflective element until reaching lateral sides of the LED 204B. Upon reaching the lateral sides of the LED 204B, the light emissions 214 pass into the diffuser 208. In this manner, nearly all of the emitted light is able to be captured and directed toward the display panel 209, leaving very little amounts of light lost.
(26) Additionally, and/or alternatively, in some instances, reflective element 222 disposed on the side of the LED opposite the substrate 202 may be formed of a material that provides a partially reflective surface while still remaining somewhat translucent so as to permit some light emissions 216 to pass through the reflective surface and out through the display panel 209. For example, the reflective surface may be formed of a very thin layer of silver (e.g., less than a particular thickness).
(27) Also depicted in view 212 of
(28) The material of the circuit trace 220 may include, but is not limited to, silver, copper, gold, carbon, conductive polymers, etc. In some instances, the circuit trace 220 may include a silver-coated copper particle. A thickness of the circuit trace 220 may vary depending on the type of material used, the intended function and appropriate strength or flexibility to achieve that function, the energy capacity, the size of the LED, etc. For example, a thickness of the circuit trace may range from about 5 microns to 20 microns, from about 7 microns to 15 microns, or from about 10 microns to 12 microns.
(29) With respect to the reflective elements of LED 204B as shown in view 212, in some instances, reflective element 222 may extend across an entirety of a width of the LED 204B, or alternatively, a reflective element 224 may extend substantially across or partially across the width of the LED 204B. A reflective element that extends across an entirety of the width of the LED, or a reflective element that extends only partially across a width of the LED may be used on either side of the LED. Additionally, and/or alternatively, both reflective elements within an LED may be the same size and extend all the way across the width of the LED, or partially across the width of the LED.
(30) Similar to
(31) As depicted in
(32) Additionally, and/or alternatively, in some instances, a gap or spacing is intentionally included between the LED 304A and diffuser 308, wherein a different optical coupling may be incorporated. In some instances of an embodiment including a gap, phosphor 330 may be deposited on the LED 304A and around at least the sides the LED 304A so as to optically couple the LED 304A and diffuser 308 by filling in the gap and diffusing the light emissions before the light emissions enter the diffuser 308. Using phosphor is particularly useful when white light is needed. In other instances of an embodiment including a gap, a material 340, such as silicone, phosphor, etc. may be deposited around the sides the LED 304B so as to optically couple the LED 304B and diffuser 308 by filling in the gap and diffusing the light emissions before the light emissions enter the diffuser 308. Note that the quantity of light emissions depicted as passing through a top surface of the LEDs 304A and 304B are different. As previously mentioned, the reflective surfaces 306A and 306B among respective LEDs may differ in transparency ranging from completely opaque to allowing a desired amount of light through to the display panel 309.
(33) Moreover, the structural concept of the nested diffuser (208, 308) is contemplated and configured to be used for light distribution and diffusion in a variety of ways. That is, the nested diffuser may be implanted without a display panel and is suited to provide diffused light for devices other than LCDs. In some instances, the nested diffuser includes LEDs nested therein in open cavities or through holes, as depicted in
(34) Furthermore, the light source 404 may or may not include one or more reflective elements like those depicted on LEDs 204A, 204B, 304A, 304B. It is contemplated that the diffuser substrate 402 may include texture features (discussed further herein) to assist in diffusing the light emitted from the light source. For example, in some instances, the diffuser substrate may be as thick or thicker than a height of the nested light source, and a texture may be added to a surface of the diffuser substrate.
(35) Accordingly, the implementation of the nested diffuser discussed herein is not limited to use in an LCD, and the nested diffuser may serve as a planar or substrate diffused light source for a multitude of other uses.
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(37) A side cross-section of apparatus 600, as depicted in
(38) In many instances, spacing of the height between substrate 602 and display panel 608 is interrelated with the spacing between adjacent LEDs 604. The interrelationship varies depending on the number of LEDs used, the effectiveness of the diffusion, the brightness desired, the desired thickness of the device, etc. Ultimately, the goal is to provide uniform lighting across an entirety of the surface of the display panel 608 for a user, while minimizing the number of LEDs to save on cost and power consumption, and minimizing the distance Y between substrate 602 and display panel 608 so as to keep the overall thickness of the display as thin as possible. Generally, as the value of Y decreases, the value of X decreases as well, which means that the number of LEDs in an array increases to uniformly light the display without visually noticeable points of light.
(39) In order to minimize the number of LEDs needed when reducing the distance Y, a texture may be added to the surface and/or the body of the diffuser. For example, in
(40) It is noted that the texture features 710, depicted as semi-circles in some instances and peaked depressions in other instances in
(41) In addition to the use of a first and second reflective element on the LEDs for diffusing light emitted by the LEDs through a display panel, texture features, such as those described above may work in combination with the reflective elements to provide a more uniformly lit display surface. In some instances, as seen in the plan view of diffuser 706 in
(42) An individual texture feature 802 is depicted as a circle at a first radial distance from the centroid of the location of the LED at large circle 800. Another individual texture feature 804 is depicted as a different sized circle a second radial distance from the centroid of the location of the LED at large circle 800. Note that the texture feature 804 is smaller than the texture feature 802. Further, in the series 806 of texture features, a pattern emerges showing that the texture features closest to the LED (e.g., texture feature 804) are smaller in size than the texture features radially further away from the LED (e.g., texture feature 802). That is, in some instances, as the distance between a texture feature and an LED increases, the size of the texture feature may increase in order to capture and thereby diffuse more light so as to provide uniform illumination through an entirety of the diffuser 706 and the superimposed display panel. In correlation, as the distance between the texture feature and an LED decreases, the size of the texture feature may decrease in order to reduce the amount of light being captured proximate to the light source.
(43) Although it appears in
(44) Additionally, and/or alternatively, as indicated previously, the texture features may be randomly located, while evenly distributed so as to maintain uniformity of diffusion. Creation of the texture features may be achieved via laser-etching, knurling, molding, scraping, etc.
(45) Illustrative Embodiment of a Method of Forming an LED
(46) A method 900 of creating an LED according to an embodiment of the instant application, is depicted in
(47) In the method 900, the first and second reflective elements may be formed of material such as aluminum, silver, TiO.sub.2, SiO.sub.2, HfO.sub.2, Ta.sub.2O.sub.5, or a white diffuse polymer-based reflective material. Furthermore, one or both the first and second reflective elements may be formed in a very thin layer (e.g., less than a threshold distance) such that the reflective element is translucent to some extent while still maintaining a generally reflective surface.
(48) Illustrative Embodiments of a Method of Forming a Nested Diffuser
(49) A method 1000 of creating a nested diffuser according to an embodiment of the instant application, is depicted in
CONCLUSION
(50) Although several embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the claims are not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the claimed subject matter.