Patent Application
20100102743
1. Field of the Invention
The present invention relates generally to light sources, and more specifically to a lighting unit having multiple light sources.
2. Discussion of the Related Art
A light-emitting diode (LED) is an active light source which typically exhibits characteristics such as high efficiency, low power consumption, high brightness and compact volume. A plurality of LEDs can be arranged as an LED array to form a light source, a colored light source, or a white light source by combining red, green, blue or other color LEDs.
One common use of an LED array is to form a backlight unit (BLU) that provides light for a particular application, such as a liquid crystal display (LCD). One type of BLU includes the use of a fluorescent edge light source which operates in conjunction with a waveguide and assorted optical films. Another type of BLU utilizes LEDs as an array light source and function in cooperation with multiple optical films. Yet another type of BLU relates to the use of LEDs as an edge light source which operates in cooperation with a waveguide and multiple optical films.
A common approach for forming an LED array includes use of wire bonding techniques for attaching the LEDs to an underlying substrate. Such wire bonding requires a level of care in order to properly align and place the LEDs during a process known as registration. In addition, consumer demands have driven the need for tighter tolerances, smaller array packages, and decreased fabrication costs.
In one embodiment, the invention can be characterized as a lighting unit having a substrate, a light source coupled to the substrate, the light source being configured to generate light. The lighting unit further includes an optical layer positioned over the light source and arranged relative to the substrate to define a region between a top side of the substrate and a bottom side of the optical layer, and a light reflector coupled to the optical layer. The light reflector being structured to reflect at least a portion of the light generated by the light source toward the top side of the substrate, and further structured to define a plurality of light transmissive regions which individually permit transmission of at least a portion of the light generated by the light source.
In yet another embodiment, the invention can be characterized as a lighting unit that includes first and second substrates, a first electrical conductor coupled to the first substrate and configured to receive alternating current (AC) from an AC power source, and a second electrical conductor coupled to the second substrate and configured to receive the AC current from the AC power source. The lighting unit further includes a first group of direct current (DC) light sources electrically coupled to the first electrical conductor and the second electrical conductor, wherein each of the first group of DC light sources is structured to permit current flow in a first direction to generate light, a second group of DC light sources electrically coupled to the first electrical conductor and the second electrical conductor, wherein each of the second group of DC light sources is structured to permit current flow in a second direction to generate light.
The above and other aspects, features and advantages of several embodiments of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings.
a-13h depict a method of making a lighting device for a lighting unit in accordance with an embodiment of the present invention.
a-14d depict a light source in accordance with an embodiment of the present invention.
a and 21b depict a light source in accordance with yet another embodiment of the present invention.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.
The following description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of exemplary embodiments. The scope of the invention should be determined with reference to the claims.
Light reflector 115 is typically structured to reflect at least a portion of the light generated by one or more of LEDs 110 toward the top side of substrate 105. In addition, the light reflector may be further structured to define a plurality of light transmissive regions 130 which individually permit transmission of at least a portion of the light generated by the light source. The transmitted light may include light that is directly received from one or more of the LEDs, light reflected from substrate 105, and combinations thereof.
Light reflector 115 may be implemented using any of a variety of different materials which can reflect light. Examples of such materials include metal (e.g., aluminum, gold, silver, nickel, copper, Molybdenum, Chromium), metal alloys, plastic, combinations thereof, and the like. In various embodiments, light reflector 115 also functions as an electrical conductor to supply power to one or more of the LEDs.
LEDs 110 are shown individually coupled to light reflector 115 via electrically conductive adhesive 135, and to substrate 105 via electrically conductive adhesive 140. Adhesive 135 functions to electrically couple a first contact or portion (e.g., p-type semiconductor) of LEDs 110 to light reflector 115, and adhesive 140 functions to electrically couple a second contact or portion (e.g., n-type semiconductor) of LEDs 110 to electrical conductor 145. The LEDs may therefore be powered to generate light responsive to current supplied to reflector 115 and conductor 145.
Adhesives 135, 140 are examples of a technique that may be used to couple associated components such as light reflector 115 and substrate 105. According to alternative embodiments, such adhesives may alternatively or additionally be implemented using any of a variety of different types of bonding materials. Examples of such bonding materials include an eutectic, solder, wave solder, and the like. If desired, the bonding material implemented may be formed as a weld or a wire bond.
LEDs 110 are but one example of a light source that may be implemented in lighting unit 100. Accordingly, the lighting unit may be implemented using various types of light sources including, for example, semiconductor LEDs, electroluminescence (EL), organic LEDs (OLEDs), and the like. Such lighting sources may be AC devices powered via alternating current, DC devices powered via direct current, and DC devices powered via alternating current. The LEDs may be implemented using the same or different colored LEDs (e.g., red, green, blue, white, and the like). For clarity and ease of discussion, various embodiments will be described with regard to light sources implemented using LEDs, but it is understood that such teachings apply equally to other types of light sources.
Substrate 105 may be implemented using assorted materials and structures. In general, the substrate is generally structured to support the light sources of lighting unit 100. In some embodiments, some or all of the top surface of the substrate includes reflective material. In such embodiments, the top side of the substrate is structured to reflect light toward the bottom side of optical layer 120. The reflective material may be in the form of a coating disposed on the substrate, or the reflective material may otherwise be formed within the substrate. The substrate may be formed using a printed circuit board (PCB), a flexible PCB, metal, plastic, paper, and cloth, among others.
Optical layer 120 is generally formed using material which is at least partially light transmissive. An example is to form the optical layer using a substantially transparent film such as polyethylene terephthalate (PET).
Various components (e.g., light reflector 115, adhesives 135, 140, LEDs 110, etc.) of lighting unit 110 are shown having assorted patterns in order to clearly illustrate and distinguish such components. It is understood that these components do not necessarily include such patterns in actual implementations. This understanding applies also for the other lighting units disclosed herein.
A required or desired light distribution (e.g., uniform) may therefore be achieved by using any of a variety of different techniques. In some embodiments, a particular light distribution may be achieved by varying aperture size, patterns, geometry (e.g., rectangular, circular, oval, triangular, polygonal, etc.), location, number of apertures, and combinations thereof, of various transmissive regions 130. For instance, light reflector 115 may be structured such that aperture size of each of the light transmissive regions 130 is determined or otherwise varied as a function of distance from an associated one of the LEDs 110. Another example includes configuring the light reflector such that aperture size of the light transmissive regions increases or decreases as a function of distance from an associated one of the LEDs.
A further example relates to light reflector 115 being defined by a plurality of reflector regions that are individually associated with one of the LEDs 110. In this example, each of these reflector regions may be structured such that aperture size of the plurality of light transmissive regions located in an associated one of the reflector regions is determined as a function of distance from an associated one of the LEDs.
Some embodiments implement light transmissive regions 103 which are the same or similarly sized. In such embodiments, light reflector 115 may be structured so that the number of light transmissive regions 130 is determined as a function of distance from an associated one of the plurality of light sources. A specific case is one in which the number of such transmissive regions increases or decreases as a function of distance from an associated light source.
To further illustrate various configurations of light reflector 115,
In accordance with further embodiments, lighting unit 100 may be configured with almost any number of LEDs, ranging from as few as one LED to as many as several thousand, or more, LEDs. The LEDs may also be arranged in various arrays and patterns to meet a desired or required arrangement.
In addition, with regard to a second side of light reflector 115, the LEDs of lighting unit 600 are powered to generate light in a manner that differs from that shown in
One purpose of electrical conductor 705 is to electrically couple a first contact or portion (e.g., p-type semiconductor) of LEDs 110 to a power source (not shown in this figure). In addition, adhesive 140 functions to electrically couple a second contact or portion (e.g., n-type semiconductor) of LEDs 110 to electrical conductor 145, which is also in communication with the power source.
The lighting unit of
In addition, with regard to a second side of the associated LED 110, lighting unit 800 includes adhesive 135 to electrically couple a first contact or portion (e.g., p-type semiconductor) of LEDs 110 to electrical conductor 610, and adhesive 140 to electrically couple a second contact or portion (e.g., n-type semiconductor) of LEDs 110 to electrical conductor 145. As before, the LEDs may be powered by applying current to conductors 145, 610. Lighting unit 800 also includes light reflector 115 coupled to the top side of optical layer 120. This feature is similar in many respects to that shown in
Since lighting unit 900 utilizes electrical conductors 145, 160 to power LEDs 110, light reflector 115 may therefore be implemented without trace lines which connect to a power source. In addition, the light reflector may also be implemented using non-conductive materials since the light reflector is not needed for supplying current to the LEDs.
As one example, a positive conductive path of lead 1005 may be in electrical communication with electrically conductive light reflector 115 (
Power source 1000 may be implemented using a device or system which can provide power to the various LEDs of the lighting unit. As such, the power source may provide alternating current or direct current. In some embodiments, the power source may be implemented using a stored power device such as a battery.
The arrangement of
In some embodiments, spacer material 1105 includes a phosphor or other material that is reactive to light generated by one or more of the LEDs 110. A particular example is to include yellow phosphor and to implement one or more of the LEDs 110 using a blue LED. In this arrangement, the blue light from the LED combines with the yellow phosphor, resulting in a substantially white light. Another feature of spacer material 1105 is that it provides an additional degree of support for the associated structures, such as LEDs 110 and optical layer 120, for example.
Since separate spacer material 1105 is located relative to LEDs 110, the spacer material further defines a region between the bottom side of optical layer 120 and the top side of substrate 105. In
The relatively greater portions of spacer material 1205 provide an assortment of potential benefits. For instance, the depicted arrangement provides for additional structural support for surrounding components. Moreover, the greater quantities of spacer material allows for the introduction of greater amounts of additional materials, such as reflective participles, light-reactive phosphors, and the like. In accordance with other embodiments, use of the spacer material in
a-13h depict a method of making a lighting device for a lighting unit in accordance with an embodiment of the present invention. One operation includes coupling a light source, such as LED 110, to substrate 105. This operation may be accomplished by providing conductive adhesive 140 on the substrate (
d depicts an optional feature of providing spacer 1305 over substrate 105. Spacer 1305 may be implemented using any of the spacer materials previously described.
g includes coupling light reflector 115 to optical layer 120. Recall that the light reflector may be structured to reflect at least a portion of the light generated by LED 110 toward a top side of substrate 105, and is also structured to define a plurality of light transmissive regions which individually permit transmission of at least a portion of the light generated by the LED.
h depicts positioning optical layer 120 over LED 110 to define a region within which spacer 1305 is located. If desired, reflective material may be located relative (e.g., above, disposed over, integrated within, etc.) to the top side of substrate 105.
a-14d depict a light source in accordance with an embodiment of the present invention. In general, LEDs 1400 may be implemented using any of the lighting sources disclosed herein, including AC lighting sources, DC lighting sources, LEDs. OLEDs, and the like. In
In accordance with various embodiments, LED 1400 includes first contact 1410 located along a corner of the p-type region, and second contact 1415 along a corner of the n-type region. As will be described in later figures, the first and second contacts are structured to permit coupling to a suitable power source to permit powering of the LED.
a-14d show LED 1440 as it is rotated clockwise, which illustrates the positioning of the first and second contacts 1410, 1415. In general, first and second contacts 1410, 1415 may each be formed along a plurality of substantially planar surfaces. In this example, the plurality of substantially planar surfaces associated with first contact 1410 are arranged to define a first corner, and the plurality of substantially planar surfaces associated with second contact 1410 are arranged to define a second corner. In an embodiment, the first corner opposes the second corner for each of these LEDs.
In an embodiment, LEDs 1400 are each implemented as a direct current (DC) light source which is powered by alternating current provided by power source 1000. Conductor 1520 is shown connected to the positive side of power source 1000, and conductor 1505 is shown connected to the negative side of the power source.
The LEDs shown in
The center-two LEDs 1400 have the opposite arrangement such that these LEDs permit current flow in the opposite direction since these LEDs have a first contact 1410 that couples with the negative side of the power source via conductor 1505 and a second contact 1415 that couples with the positive side of the power source via conductor 1520. Operation of the embodiment of
Each of the LEDs of lighting unit 1500, such as those depicted in
It is understood that at any given time, a percentage of the LEDs of lighting unit 1500 will not be generating light. Such a potential drawback can be minimized, or effectively eliminated, by implementing sufficient numbers of LEDs in the lighting unit.
A number of potential advantages may be achieved using the depicted arrangement of lighting unit 1500. First, a lighting unit may be formed using a low-cost printing process, for example, to place or otherwise locate the LEDs. This is because the LEDs can be powered regardless of their orientation relative to the first and second conductors 1505, 1520. In addition, such placement does not require costly and time-consuming precision registration. Further, lighting unit 1500 may be implemented using DC LEDs as a light source, which are significantly cheaper than AC LEDs. Still further, the lighting unit can be directly coupled to an AC power source, without the need for a transformer to convert the AC into direct current.
According to
In accordance with various embodiments, LED 1900 includes first contact 1910 located a top surface of p-type region, and second contact 1915 along a top surface of the n-type region. The first and second contacts are structured to permit coupling to a suitable power source to permit powering of the LED. In general, the top surfaces of the p-type region and the n-type regions are substantially planar. Note also that LED 1900 has a length that is greater than its height. A potential benefit of this configuration is that it permits the LED to be readily positioned over a substrate in one of two orientations; namely, the p-type region over the n-type region, or vice-versa. LEDs that are positioned on either end can be easily identified and either removed or repositioned so that they are orientated correctly.
LED 1900 may be implemented in any of the lighting units disclosed herein, including lighting unit 1500 of
In
a and 21b depict a light source in accordance with yet another embodiment of the present invention. These figures depict a light source implemented as an LED structured as a cube. As an example, LED 2100 includes a p-type region and an n-type region, with an associated p-n junction 2105.
In accordance with various embodiments, LED 2100 includes first contact 2110 located along a top and side surface of the p-type region, and second contact 2115 along a top and side surface of the n-type region. The first and second contacts are structured to permit coupling to a suitable power source to permit powering of the LED.
a shows first contact 2110 along a top side of the p-type region, and second contact 2115 along a right side of the n-type region.
LED 2100 is shown as a cube defined by a plurality of substantially planar surfaces. First contact 2110 is defined by two surfaces which lie in planes that are approximately 90 degrees relative to one another, such that the first contact has one surface along the top side (
In an embodiment, the first and second contacts are on opposing edges of the LED. If desired, the first contact 2110 may be located along any of the edges of the p-type region, and second contact 2115 may likewise be located along any of the edges of the n-type region.
In general, the various LEDs of
The various lighting systems and light sources that have been described may be implemented in assorted systems and applications in accordance with embodiments of the present invention. An example of such embodiments includes use as a backlighting unit, an LED display, an LCD display, and the like.
