PATENT DOCUMENT

Publication Number: US-8339028-B2
Application Number: US-49535309-A
Country: US
Kind Code: B2

Title: Multicolor light emitting diodes

Abstract:
A device such as a multicolor light emitting diode that emits different colors of light and that may combine the different colors emitted by individual light emitting diodes. The multicolor LED may include a common anode terminal that may be connected to each anode of the individual light emitting diodes. The multicolor LED may be a five terminal multicolor LED. Additionally, the multicolor LED may include two anode terminals, in which the first anode terminal may be a common anode terminal connected to three of the individual color LEDs and the second anode terminal may be connected to an anode of a white LED. In this embodiment, the multicolor LED may be a six terminal multicolor LED.

Claims:
1. A multicolor light emitting package comprising:
 a white light emitting diode operative to emit a white light; 
 a multicolor light emitting diode operative to emit a colored light;
 a first light guide optically coupled to the white light emitting diode and having a first ramp shape; and 
 
 a second light guide optically coupled to the multicolor light emitting diode and having a second ramp shape, the second light guide adjacent the first ramp-shaped light guide; 
 the first and second light guides configured to combine the white light and the colored light, thereby producing an output light. 
 
     
     
       2. The multicolor light emitting package of  claim 1  further comprising:
 a housing enclosing at least the at least one light guide; and 
 a window defined by the housing, wherein the outputted light travels through the window. 
 
     
     
       3. The multicolor light emitting package of  claim 1  further comprising four cathode terminals and a common anode terminal, wherein the cathode and the anode are connected to the housing, further wherein each one of the four cathode terminals is operationally connected on a one to one basis to each of the cathodes of the white, red, green and blue light emitting diodes and the common anode terminal is operationally connected to all of the anodes of white, red, green and blue light emitting diodes. 
     
     
       4. The multicolor light emitting package of  claim 3  wherein the housing comprises six terminals wherein two of the terminals are both operationally connected to all of the anodes of the white, red, green and blue light emitting diodes. 
     
     
       5. The multicolor light emitting package of  claim 1  further comprising a first and a second anode terminal, both of which are connected to the housing wherein, the first anode terminal is a common anode terminal operationally connected to all of the anodes of the red, green and blue light emitting diode, further wherein the second anode terminal is connected to the anode of the white light emitting diode. 
     
     
       6. The multicolor light emitting package of  claim 1 , wherein the multicolor light emitting diode comprises:
 a red light emitting diode; 
 a blue light emitting diode; and 
 a green light emitting diode; wherein each of the red, blue and green light emitting diodes are optically coupled to the at least one light guide. 
 
     
     
       7. The multicolor light emitting package of  claim 6  wherein the white, red, green and blue light emitting diodes are arranged in a two by two grid. 
     
     
       8. The multicolor light emitting package of  claim 6  wherein the white, red, green and blue light emitting diodes are linearly arranged in a one by four grid. 
     
     
       9. The multicolor light emitting package of  claim 1  wherein:
 the first light guide comprises:
 a first ramp-shaped section and a first elongate extension, the first ramp-shaped section and the first elongate extension contiguous with one another; and 
 
 the second light guide comprises:
 a second ramp-shaped section and a second elongate extension, the second ramp-shaped section and the second elongate extension contiguous with one another. 
 
 
     
     
       10. The multicolor light emitting package of  claim 9 , wherein:
 the first light guide is located above the second light guide; and 
 the second light guide is configured to transmit light through the first light guide.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to U.S. nonprovisional application Ser. No. 12/495,230, titled “Multicolor Lighting System,” identified as and filed on Jun. 30, 2009, which is incorporated herein as if set forth in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention generally relates to light emitting diodes and, more specifically, to multicolor light emitting diodes. 
     2. Background Discussion 
     Many electronic components, devices and/or systems employ some type of light source which may be used for various purposes such as providing light for better visibility, decoration, indicators, imaging and so on. Depending on the use, the type of light source may be fluorescent, halogen, incandescent, mercury vapor, high pressure or low pressure sodium, light emitting diodes (“LEDs”) and so on. 
     In particular, LEDs may be used in a number of applications and may provide light more efficiently. They may also yield increased performance lifetimes over other light sources such as, incandescent lights. Additionally, LEDs may have other advantages such as smaller packaging sizes, increased power efficiency and so on. LEDs may also produce and/or transmit less thermal energy, thus keeping the casing and/or packaging surrounding the LEDs cooler than other light sources. 
     Although LEDs may more efficiently produce light than many of the previously mentioned traditional light sources, the intensity of the light emitted by LEDs may not be sufficient for some purposes and/or a greater intensity of light may be desirable. For example, a greater light intensity may be desirable for employing LEDs as indicators, light sources for visibility, backlighting, imaging and so on. Additionally, the LED light intensity may depend on the LED color. In one example, red light may have a greater intensity than blue light at the same power, but it may be desirable to display the colors at similar intensities. Accordingly, there is a need in the art for an improved device that includes the ability to provide multiple colors at a range of intensities. 
     SUMMARY 
     Generally, one embodiment of the present invention may take the form of a multicolor light emitting diode. The multicolor light emitting diode may include a first light emitting diode that emits white light, a second light emitting diode that emits red light, a third light emitting diode that emits green light, a fourth light emitting diode that emits blue light and a housing surrounding at least the first light emitting diode, the second light emitting diode, the third light emitting diode and the fourth light emitting diode. The multicolor light emitting diode may also include a window defined in the housing, such that each of the first, second, third, and fourth light emitting diodes may emit light through the window. Additionally, the multicolor light emitting diode may include four cathode terminals and a common anode terminal, such that the cathode and the anode may be connected to the housing. Each one of the four cathode terminals may be operationally connected on a one to one basis to each of the cathodes of the first, second, third and fourth light emitting diodes and the common anode terminal may be operationally connected to all of the anodes of first, second, third and fourth light emitting diodes. 
     Another embodiment may take the form of a method for providing colors of light. In this method a first light emitting diode that emits white light may be provided, as well as a second light emitting diode that emits red light, a third light emitting diode that emits green light, a fourth light emitting diode that emits blue light. Additionally, at least the first light emitting diode, the second light emitting diode, the third light emitting diode and the fourth light emitting diode may be surrounded by a housing. Separate windows may be defined in the housing for each of the first, second, third, and fourth light emitting diodes so that the light emitted by each may pass through the separate windows. Additionally, four cathode terminals and a common anode terminal may be connected to the housing and each one of the four cathode terminals may be operationally connected on a one to one basis to each of the cathodes of the first, second, third and fourth light emitting diodes, and the common anode terminal may be operationally connected to all of the anodes of first, second, third and fourth light emitting diodes. 
     These and other advantages and features of the present invention will become apparent to those of ordinary skill in the art upon reading this disclosure in its entirety. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts an embodiment of a multicolor LED schematic. 
         FIG. 2  depicts an embodiment of the present invention as a top firing five terminal multicolor LED package. 
         FIG. 3  depicts another embodiment of the present invention as a side firing five terminal multicolor LED package. 
         FIG. 4  depicts another embodiment of a multicolor LED schematic. 
         FIG. 5  depicts another embodiment of the present invention as a top firing six terminal multicolor LED package. 
         FIG. 6  depicts another embodiment of the present invention as a side firing six terminal multicolor LED package. 
         FIG. 7  depicts yet another embodiment of the present invention in another LED multicolor package. 
         FIG. 8  depicts a top-down view of an alternative multicolor LED package. 
         FIG. 9  depicts a cross-sectional view of the LED package of  FIG. 8 , showing one sample cross-section taken along line A-A of  FIG. 8 . 
         FIG. 10  depicts an alternate cross-sectional view of the LED package of  FIG. 8 , showing a second sample cross-section taken along line A-A of  FIG. 8 . 
         FIG. 11  depicts a top-down view of yet another multicolor LED package. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Generally, one embodiment may take the form of an electronic device, such as an LED, which may be capable of emitting various colors individually or in combination. In this embodiment, the LED may be a multicolor LED, which may include and incorporate multiple individual LEDs that may emit different colors of light from one another. For example, the multicolor LED may include individual LEDs, each emitting one of red, green, blue and white light. Generally, an LED that emits red light may be referred to herein as a “red LED,” an LED that emits green light may be referred to herein as a “green LED,” and so on. Continuing this example, the multicolor LED may emit white light in various ways, such as by combining the emitted colors of the red LED, the green LED and the blue LED, by using the white LED alone, and/or any combination thereof. 
     Continuing the description of the embodiment, the multicolor LED may be packaged in a number of ways. In one example, light may be emitted from the top of the package. In another example, light may emanate from the side of the package. In other embodiments the light may be emitted from any package surface depending on the configuration of the LED package. For example, the multicolor LED may be a top-firing multicolor LED and the multicolor LED packaging may allow light to be emitted from a transparent window defined in the top of the package. 
     Continuing the embodiment, the multicolor LED may be configured so that two or more of the individual LEDs may share a common anode, each LED may have an individual anode, or all of the individual LEDs of the multicolor LED may share a common anode. For example, the red LED, the green LED and the blue LED may share a common anode and the white LED may have a separate anode, all four of the LEDs may share a common anode and so on. 
     Another embodiment may take the form of a method for producing various colors, including white light, from a single device such as a multicolor LED. The multicolor LED may include individual LEDs, each of which may emit different colors from one another (or some of the individual LEDs may emit different colors than others). By combining the different colors emitted by the individual LEDs, the resulting emitted color may be a different color, or may be a different intensity color. For example, the multicolor LED may emit a white light by combining red, green and blue colors emitted respectively by a red LED, a green LED and a blue LED and may increase the intensity of the white light by additionally combining white light emitted by a white LED. Additionally, white light may be produced at a better power efficiency by combining the emitted light from the red, green, blue and white LEDs, then by producing white light by combining only the emitted light from the red, green and blue LEDs without the white light from the white LED. 
     It should be noted that embodiments described herein may be used in a variety of image processing and/or lighting systems. The embodiment may include or work with a variety of display components, monitors, screens, images, sensors, indicators and electrical devices. Aspects of the present invention may be used with practically any apparatus related to optical and electrical devices, display systems, presentation systems or any apparatus that may contain any type of display and/or lighting system. Accordingly, embodiments of the present invention may be employed in computing systems and devices used in visual presentations and peripherals and so on. 
     Before explaining the disclosed embodiments in detail, it should be understood that the embodiments are not limited in their application to the details of the particular arrangements shown, because other embodiments are possible. Also, the terminology used herein is given for description and not limitation. 
       FIG. 1  depicts a schematic of a sample electronic device  100 . The electronic device  100  may be a multicolor LED  100  configured to emit one or more colors of light. Typically, multicolor LEDs include more than one individual LED, each of which may emit a certain wavelength of light corresponding to a color range. Generally, a single LED emits wavelengths of a single color, such as red. By varying either the duty cycle of or voltage to the LED, the intensity of the emitted light may be varied. For some LEDs, changes in input voltage may yield changes in the outputted light&#39;s wavelength. Each individual LED of the multicolor LED may emit the same color or may emit different colors. For example, a multicolor LED may have four LEDs and all of the four LEDs may emit red light, or two of the four LEDs may emit red light, one LED may emit green light and the remaining LED may emit blue light, or each of the LEDs may emit a different color light from all others. Additionally, multicolor LEDs may include various numbers of individual LEDs as appropriate. In another example and as shown in  FIG. 1 , the multicolor LED  100  may be housed in a single package and may include four individual LEDs, specifically a white LED  130 , a red LED  132 , a green LED  134  and a blue LED  136 . 
       FIG. 1 , depicts a multicolor LED that produces different colors from each of the individual LEDs. Although LED  100  includes only four LEDs, the multicolor LED  100  may contain any number of individual LEDs greater than one LED, in which the individual LEDs may produce the same or different colors as one another. Additionally, although the LEDs  130 ,  132 ,  134  and  136  are depicted as configured in a specific order left to right in  FIG. 1 , and with specific colors, the individual LEDs of a multicolor LED may configured in various arrangements, may include fewer LEDs or a greater number of LEDs, and may emit various colors. 
     Generally, LEDs may emit light in wavelengths across the visible, ultraviolet and infrared spectrum. In the example of  FIG. 1 , the multicolor LED  100  may emit colors other than those generated by a single LED by combining two or more colors to produce a color other than red, green, blue or white. Combining colors to produce a different color may be referred to as “additive color mixing.” For example, the LED may emit a magenta color by combining red and blue light. In another example, the LED may emit white light by combining equal intensities of red, green and blue light. Combining different colors of light with white light will be discussed in more detail below. Although a specific color may be referred to herein, it should be understood that such a color may any of a range of wavelengths. For example, the color produced by an LED emitting light between the wavelengths 610 nanometers (nm) and 760 nm may appear, and be referred to as “red.” 
     LED colors may be combined to produce different colors, but may also be combined to change the saturation of the color and/or to provide a greater intensity. As used herein, saturation generally refers to the amount of white light in the resulting color. For example, white light and red light may be combined to produce a resulting color and may be referred to as a pastel red (a less saturated red). Each of these effects will be discussed in further detail below. 
     The resulting color may be distinct from the color emitted by either of the two light sources or may appear as a similar color to one of the two light sources. For example, a light emitted by a red LED and a blue LED may be combined to produce a yellow color, in which the yellow color may be at a greater intensity than either one of the colors emitted by the red LED or the blue LED when viewed individually. In another example, the light emitted by a red LED and a white LED may be combined to emit a reddish color, which may be at a greater intensity than light emitted by either one of the red LED or the white LED when viewed individually. The combined emitted light may be a more pastel red color (less saturated red), than the red light emitted by the red LED when viewed individually. Generally, adding together the light emitted from two or more light sources, both at a defined power, may result in an outputted light having increased intensity as well as a different tint or saturation when compared to either one of the two constituent light sources individually. 
     By varying the light intensities of the light emitted by each of the individual LEDs, the combinations of colors may also be varied. Generally, an LED may emit a color at different intensities. For example, although the red light emitted by the red LED  132  may also be combined with the white light emitted by the white LED  130  to produce a pastel (although intense) color red, the two emitted colors may have different intensities. Continuing this example, the red light emitted by the red LED  132  may be at a minimum intensity and the white light emitted by the white LED  130  may be at a maximum intensity, thus producing a pale pink-white light. Alternatively, the red light emitted by the red LED  132  may be at a maximum intensity and the white light emitted by the white LED  130  may be at a minimum intensity and produce a less saturated red color that may appear as a slightly faded reddish color. The color combinations produced by varying the light intensities of the light emitted by the individual LEDs may or may not fall within either one of the frequency ranges of the light emitted by the individual LEDs. 
     In the embodiment of  FIG. 1 , white light may be produced in various ways such as by combining the three emitted colors of red LED  132 , green LED  134  and blue LED  136 , or by emitting white light from the white LED  130  or by combining various other colors in combination as appropriate to produce white light. Stated differently, combining any number of colors in the appropriate combinations may also produce white light. For example, the magenta light emitted by a magenta LED in combination with the green light emitted by a green LED may produce white light. 
     Additionally, as previously discussed, a multicolor LED may emit white light with increased intensity by combining the light emitted by the combination of the three LEDs (red LED  132 , green LED  134 , blue LED  136 ) and the white LED  130 . The white LED  130  may be used in combination with the three LEDs  132 ,  134 ,  136  of  FIG. 1  in order to increase the intensity of the white light produced by the three LEDs, or may be used to increase the power efficiency of LED  100 . For example, assuming the same intensity, the white LED  130  may produce a white light more efficiently in comparison to producing a white light using the three LEDs in combination to produce white light. Generally, power efficiency of an LED, as discussed herein, may refer to the light output per unit power input. 
     Generally an LED may have a cathode and an anode. As used herein, the phrases regarding the LED being forward biased, switched “on” or with a closed switch, all refer to the same LED state and all indicate that the individual LEDs may emit light when in the aforementioned state. 
     Still with respect to  FIG. 1 , the white LED  130 , red LED  132 , green LED  134  and blue LED  136  may be operationally or directly connected and in parallel with one another. The multicolor LED  100  may include a common anode  120  and separate cathodes  110 ,  112 ,  114 ,  116 . The anodes and cathodes of LEDs  130 ,  132 ,  134  and  136  may be operationally or directly connected to the respective package terminals and the connections will be described in further detail below. Generally, common anodes may provide increased flexibility of use. For example, a multicolor LED with a common anode may include multiple terminals connected to the common anode, thus providing a greater number of ways to connect to the common anode of the multicolor LED. 
     In  FIG. 1 , the white LED  130  is connected to the common anode  120 . Similarly, the red LED  132 , green LED  134  and blue LED  136  are also connected to the common anode  120 . Further, the white LED  130  may be connected to a first cathode  110 , the red LED  132  may be connected to a second, separate cathode  112 , the green LED  134  may be connected to a third, separate cathode  114  and the blue LED  136  may be connected to a fourth, separate cathode  116 . Generally, the common anode may be connected to two or more of the LED anodes, which will be discussed in further detail below with respect to  FIGS. 4-6 . 
       FIG. 2  depicts a top view of one example embodiment of a top firing five terminal LED package  200 . The embodiment shown in  FIG. 2  has the same LED connections shown in  FIG. 1 . The LED package  200  may emit light from the top of the package and may house a multicolor LED like that shown in  FIG. 1 . Although the examples discussed herein with respect to  FIGS. 1 and 2  use the colors white, red, green and blue, any color LED may be used. 
     As shown in  FIG. 2 , the LED package  200  may include one window through which the colors emitted by the multicolor LED may pass. Alternative embodiments may have multiple windows. For example, the LED package may include four windows, in which each window emits the light emitted by one of the individual LEDs. In another example, the LED package may include two windows, in which the light emitted by the white LED may pass through a first window and the light emitted by the red, green and/or blue LED may pass through a second window. 
     The light emitted from the individual LEDs may be coupled using a light guide (not shown) located within, adjacent to, or formed as part of the LED package  200 . Depending on the configuration of the individual LEDs (discussed below), one or more light guides may be used inside the LED package to couple the light from the LED through the LED package window. As discussed herein, the term LED may also include LED die. For example, one light guide may couple the light from the four LEDs such that the light emitted from any one of the four LEDs may be emitted from the window of the LED package. Alternatively, the LED package may have two windows, thus, two light guides may be used. A first light guide may couple light from the white LED through the first window and the second light guide may couple light from any of the red, green and/or blue LEDs through the second window. 
     Additionally, the physical arrangement of the individual LEDs within the package as shown in  FIG. 2 , may be arranged in a two by two grid, may be arranged in a horizontal linear pattern, a vertical linear pattern or any grid or pattern including randomly. The configuration of the LEDs within the package may depend on the intended use of the package, the size of the LEDs, the desired uniformity of the color to be emitted from the package and so on. For example, the white LED may be centrally located and the red, green and blue LEDs may be arranged around the white LED to increase the color uniformity and intensity uniformity of the emitted light from the multicolor LED. 
     The LED package  200  in  FIG. 2  has six physical terminals, including five functionally different terminals, and thus the LED package  200  may be referred to herein as a “five terminal LED” package. Two of the terminals, namely a first anode terminal  220  and a second anode terminal  222  may be operationally or directly connected to the common anode of the multicolor LED. Although the LED package  200  includes two anode terminals, the first anode terminal  220  and the second anode terminal  222 , both of the anode terminals may functionally serve the same purpose. Stated differently, the first and second anode terminals  220  and  222  of  FIG. 2  may both be operationally or directly connected to common anode  120  of  FIG. 1  and may be used interchangeably. Different anode connections will be discussed in further detail below. 
     LED package  200  also may include four cathode terminals as shown in  FIG. 2 . Cathode terminal  210  may be operationally or directly connected to the cathode of white LED  110  of  FIG. 1  and cathode terminals  212 ,  214  and  216  may be operationally or directly connected to the cathodes of red LED  112 , green LED  114  and blue LED  116  of  FIG. 1 . Generally, terminals may be referred to as operationally connected in various arrangements that allow the terminal to operate in a similar manner as a direct connection. For example, a terminal may be operationally connected even though an additional electrical component such as a resistor may be inserted in the connection between the terminal and the LED. Additionally, the terminals may be located such that the LED package  200  may be used interchangeably with other six terminal device packages. The LED package may be sized such that a backlit keyboard may have one LED package underlying and backlighting each individual key. However, the size of the LED package  200  may depend on the intended use of the LED package, on the size of the individual LED die and so on. 
       FIG. 3  depicts a side view of another example embodiment of a side firing five terminal LED package  300 . The embodiment shown in  FIG. 3  has the same LED connections shown in  FIG. 1 . The LED package  300  may emit light from the side of the package through a transparent window and, similar to the LED package  200  of  FIG. 2 , may enclose a multicolor LED. In  FIG. 3 , the multicolor LED package  300  may include individual LEDs  330 ,  332 ,  334  and  336  which may emit white, red, green and blue light respectively. The individual LEDs may be configured within the multicolor LED as described in  FIG. 1 . Although the examples discussed herein use the colors white, red, green and blue, any color LEDs may be used. 
       FIG. 3  has six physical terminals, including five functionally different terminals. The first and second anode terminals  320  and  322  may be operationally or directly connected to the common anode of the multicolor LED. As previously discussed with respect to  FIG. 2 , although the LED package  300  includes two anode terminals  320  and  322 , both of the anode terminals may functionally serve the same purpose in that either one of the anode terminals  320 ,  322  may be used interchangeably. 
     The side firing LED package  300  also may include four cathode terminals. Cathode terminal  310  may be operationally or directly connected to the cathode of white LED  310  of  FIG. 3  and cathode terminals  312 ,  314  and  316  may be operationally or directly connected to the cathodes of red LED  312 , green LED  314  and blue LED  316  of  FIG. 3 . Additionally, although the die and the LED package terminals are depicted in a specific order, the die and the package terminals may be arranged in any order. Also, the anode terminals  320 ,  322  of  FIG. 3  are shown adjacent to one another, but may be located in any position on the LED package, including alternating with the cathode terminals, at opposite ends of the LED package and so on. Because the white LED  330  and the blue LED  336  are both connected to a common anode (shown in  FIG. 1 ), either one of the first or second anode terminals  320 ,  322  may be connected to the power source so that the LEDs  330 ,  336  may be switched on (stated differently, both first and second anode terminals  320  and  322  need not be connected to the power source to turn on LEDs  330 ,  336 ). 
     Depending on the intended use of the LED package, either of a top-firing or side-firing LED package  200  may be used. For example, for backlighting a keyboard, the top-firing LED package may be used as it allows light to be emitted from the top of the package. Stated differently, in a backlit keyboard, the multicolor LED may be located beneath the keyboard, thus making it useful to employ a top firing LED package. 
       FIG. 4  depicts a schematic of another embodiment of an electronic device  400 . The electronic device  400  may be a multicolor LED, which may emit one or multiple colors individually or in any combination and may include individual LEDs,  430 ,  432 ,  434 ,  436 . Similar to the embodiment shown in  FIG. 1 , the individual LEDs  430 ,  432 ,  434 ,  436 , may emit the colors white, red, green and blue respectively. The schematic of  FIG. 4  includes two anodes,  420  and  422 , in which anode  422  is a common anode for the red LED  432 , green LED  434  and blue LED  436 . In the six terminal multicolor LED, the anode  422  may be connected to any three of the individual LED anodes. In one example, the anode  422  may be connected to the anodes of the white LED  430 , the red LED  432  and the green LED  434 . 
     The six terminal multicolor LED discussed with respect to  FIG. 4  is included within the LED package depicted in  FIG. 5 . Accordingly, the embodiment shown in  FIG. 5  has the same LED connections shown in  FIG. 4 .  FIG. 5  provides a top view illustration of a top firing six terminal LED package  500 . Similar to the LED packages illustrated in  FIG. 3 , the top firing LED package  500  may emit light from its top and has six physical terminals. The LED package  500  includes a first anode  520  and a second anode  522 , which may be connected to different individual LED anodes and are not interchangeable with one another since the functionality of the first and second anodes is different with respect to one another. In the embodiment of  FIG. 5 , depending on the emitted colors of light desired, either first anode  520  or second anode  522  may be connected to the power source, and thus connect the respective LED. For example, the first anode  520  may be connected to the power source and a white light may be emitted from white LED  530 .  FIG. 5  also includes cathodes  510 ,  512 ,  514 ,  516 , which may be operationally and/or directly connected to the cathodes of white LED  530 , red LED  532 , green LED  534  and blue LED  536 . 
     In one example of the embodiment shown in  FIG. 5 , the LED package may emit a red light and a white light. In this example, both of the anodes  520 ,  522  may be connected to the power source so that the LEDs  530 ,  536  may be switched on. Distinct from the embodiment shown in  FIG. 3  and as previously mentioned, anode  520  may be connected to the anode terminal of white LED  530  and anode  522  may be connected to the anodes of red, green and blue LEDs. Additionally, the cathodes  510 ,  516  may be connected to the power source so that the LEDs  330 ,  336  may be switched on and emit white and blue light respectively. 
     In another example of  FIG. 5 , the LED package  500  may emit a yellow color. In this example, the anode  522  and the cathodes of green LED  534  and blue LED  536  may be connected to the power source so that the individual blue and green LEDs may emit light. Continuing this example, the white LED  530  may not emit light as the anode  520  need not be connected to the power source. Because the anode of the white LED  530  may not be connected to a power source, white LED  530  may have the ability to be switched on even if a bias is applied to the cathode. 
       FIG. 6  depicts yet another embodiment of an LED package  600 , which may be a six terminal side firing LED package  600 . The embodiment shown in  FIG. 6  has the same LED connections shown in  FIG. 4 . As previously discussed with respect to  FIG. 3 , side-firing LED package  600  may emit light from the side of the package, may include four individual LEDs, (e.g., white, red, green and blue) and may include a window which may allow the light emitted from the individual LEDs to pass through. LED package  600  may include anodes  620 ,  622  which may be similarly connected as the anodes  420 ,  422  of LED  400 . Anode  620  may be connected to the anode of the white LED  630  and anode  622  may be connected to a common anode which, in turn, may be connected to the anodes of red LED  632 , green LED  634  and blue LED  636 . Also similar to the LED package  500  of  FIG. 5 , anodes  620  and  622  may both be connected to a power source, thus allowing any one of the LEDs to be switched on and emit light. 
     Although five and six terminal packages have been discussed herein as examples, a package may include any number of terminals. For example, an LED package may include a multicolor LED that may emit four colors. The multicolor LED may be electrically configured similar to the schematic of  FIG. 4 , in which the multicolor LED may include four individual LEDs and also may include two anodes one of which is a common anode for three of the LED (red, green and blue LEDs) anodes, and the second anode which may be connected to an individual white LED anode. The package may also include ten terminals in which four of the terminals may be connected to the cathodes of the individual LEDs, two of the terminals may be connected to the white LED anode and the remaining three terminals may be connected to the common anode for the three individual color LEDs. 
     In another embodiment, a side-firing LED package may emit a blue light and a white light, when the blue LED and the white LED are active. In this embodiment, the side-firing LED package may have four different color LEDs (for example, white, red, green, blue), and each LED may have separate anode and separate cathodes. Thus, it may be possible to produce different intensity light from each individual LED, and more than one LED may emit light at the same time. For example, the anodes of the blue and the white light may be separately connected to separate power sources so that the blue and white LEDs may be switched on and emit white and blue light respectively and the intensity of the light produced by each may be separately controlled. 
       FIG. 7  depicts yet another LED package  700 . The LED package  700  may be configured to include various numbers of terminals, but is illustrated in  FIG. 7  with five terminals. The LED package  700  may function similarly to the LED packages described herein with respect to  FIGS. 1-6 . 
       FIG. 8  depicts an implementation of a multicolor LED package  800  having two side-firing LEDs, namely one multicolor LED  810  and one white LED  820 . As shown in  FIG. 8 , the multicolor LED  810  and white LED  820  are situated at opposing sides of the light guide  830 . By positioning the LEDs in this fashion, each may have a relatively large and uniform dispersal pattern for emitted light, since neither LED is located closer to one adjacent side than the other. A package  850  may surround the LEDs and light guide and is shown in dashed lines. It should be noted that such a package is optional with respect to this or other embodiments discussed herein. Further, the package, LEDs, and/or light guide(s) generally are situated or, or electrically connected to, a base such as a printed circuit board  840 . 
       FIG. 9  shows one sample cross- section for the LED package  800  of  FIG. 8 , generally taken along line A-A of  FIG. 8 . In particular,  FIG. 9  depicts the configuration of the light guides  930 ,  940  for the multicolor LED  910  and white LED  920 . Each light guide  930 ,  940  is generally ramp-shaped in a vertical cross section and a rectangular prism in a lateral cross section (the length of the rectangular prism varying with the point at which the cross-section is taken, due to the angled edge of the ramp). The first light guide  940  directs and/or diffuses light from the multicolor LED  910  in a desired pattern in order to illuminate an item above the waveguide while the second light guide  930  does the same for the white LED  920 . It should be noted that the second light guide  930  may be configured to take into account the scattering pattern of the first light guide  940 . That is, since the second light guide is located beneath the first light guide, the two may cooperate to provide a desired final illumination pattern for the white LED. 
     In alternative embodiments, the upper, first light guide may be optically coupled to the white LED  920  and the second, lower light guide  930  optically coupled to the multicolor LED  910  (for example, the positions of the LEDs may be flipped). 
       FIG. 10  depicts an alternate construction of the LED package  800  of  FIG. 8 , particularly with respect to the configuration of the light guides  1010 ,  1020 . This cross-section may also be taken along line A-A of  FIG. 8  when the alternate construction is employed. Here, instead of being ramp-shaped like the light guides  910 ,  920  of  FIG. 9 , each light guide  1010 ,  1020  is formed from a ramp-shaped portion  1030 ,  1040  and a rectangular prism portion  1050 ,  1060 . Each ramp-shaped portion is adjacent to and contiguous with the associated rectangular prism portion. The ramp-shaped portion directs light exiting the appropriate LED  810 ,  820  either upward or downward into the rectangular prism, where the light is emitted upward. Further, the shaded areas  1070 ,  1080  at the end of each rectangular prism  1050 ,  1060  may be part of the light guide and formed from the same material, in which case they are contiguous with the adjacent rectangular prism, may be empty air or may be formed from another material, such as an insulator, opaque or reflective material. 
     Although  FIGS. 8-10  depict the multicolor LED and white LED on opposing sides of the LED package, it should be appreciated that the LEDs may be located on the same or adjacent sides. If on the same side, the LEDs may be side by side, stacked vertically, or separated. Further, some embodiments may employ multiple white LEDs, multiple multicolor LEDs, or a white LED and several color-emitting LEDs. In one sample embodiment, two white LEDs may be used. The LED light guide may have two angled corners  1110 ,  1120  extending between sides of the package  1100 , as shown to best effect in the top-down view of  FIG. 11 . The white LEDs  1130 ,  1140  may be positioned adjacent these angled corners so that light may be emitted into the interior of the package  1100  and thus into a light guide (not shown). Because each angled corner extends at approximately 135 degrees from the adjacent sidewalls, the white light emitted by the white LEDs may be evenly dispersed and mixed. It should be appreciated that a single light guide may be used for both white LEDs or both white LEDs and the multicolor LED  1150 . Again, multiple single-color LEDs may be used in place of the multicolor LED. Likewise, certain embodiments may use two multicolor LEDs and a single white LED and reverse the positions depicted in  FIG. 11 . Further, in certain embodiments the angle of the corner(s) may be more or less than 135 degrees. As yet another alternative, the package  850  may include angled corners and the LEDs may sit outside the package. 
     Although the present invention has been described with respect to particular apparatuses, configurations, components, systems and methods of operation, it will be appreciated by those of ordinary skill in the art upon reading this disclosure that certain changes or modifications to the embodiments and/or their operations, as described herein, may be made without departing from the spirit or scope of the invention. Accordingly, the proper scope of the invention is defined by the appended claims. The various embodiments, operations, components and configurations disclosed herein are generally exemplary rather than limiting in scope.

Metadata:
Filing Date: 20090630
Publication Date: 20121225
Grant Date: 20121225
Priority Date: 20090630
Inventors: PANCE ALEKSANDAR
KERR DUNCAN
BILBREY BRETT
CULBERT MICHAEL F.
Assignee: APPLE INC
CPC Classifications: [{"code": "H10H20/855", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10H20/857", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10H20/851", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10H20/855", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10H20/813", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10H20/85", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/0068", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L25/0753", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01L25/0753", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/0002", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B6/0068", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 42541510