HK1173104A - Method and system for dynamic in-situ phosphor mixing and jetting - Google Patents

Abstract

A system and method for depositing a phosphor composition onto a light emitting device improves manufacturing yield, simplifies conventional processes, and decreases costs. For example, a method of dispensing a phosphor composition onto a light emitting device includes dispensing a portion of the phosphor composition onto the light emitting device utilizing a plurality of colored phosphor dispensers each for dispensing a respective type of phosphor. Power is applied to the light emitting device to emit light, and a characteristic the light emitted by the light emitting device is detected. Phosphor mixing and phosphor dispensing are dynamically controlled. Therefore the color characteristics of phosphor dispensed on LEDs are consistent. The system and method may also reduce the difference between detected characteristic of the light and a desired characteristic of the light.

Description

Method and system for dynamic in-situ phosphor mixing and jetting

Technical Field

The present disclosure relates to the fabrication of light emitting devices and more particularly to the fabrication of broad spectrum light emitting diodes having phosphor layers.

Background

Solid state devices, such as Light Emitting Diodes (LEDs), are attractive candidates for replacing conventional light sources, such as incandescent and fluorescent lamps. LEDs have significantly higher light conversion efficiency than incandescent lamps and longer lifetimes than both types of conventional light sources. Furthermore, some types of LEDs now have higher conversion efficiencies than fluorescent light sources, and have demonstrated even higher conversion efficiencies in the laboratory. Finally, LEDs require lower voltages than fluorescent lamps and therefore provide various power saving benefits.

Unfortunately, LEDs produce light in a relatively narrow spectrum. In order to replace conventional lighting systems, it is desirable to have LED-based light sources that produce white light. One way to produce white light is to deposit a phosphor material over the LED, converting monochromatic light emitted from a blue or UV LED into broad spectrum white light. The phosphor material is formed by mixing phosphor powder into a polymer, such as silicone, at a predefined concentration or in a predefined formulation to create a suspension of phosphor particles in the silicone. This mixture is then deposited onto the LED in a predefined volume and/or weight and subsequently subjected to a curing process. The resulting phosphor-coated LEDs are then tested and placed in different color bins (bins) according to the actual test colors. Various processes for suspending phosphor particles in a silicone carrier are known in the art.

Consistent optical properties, such as color consistency, are difficult to achieve using these processes. It is often difficult to maintain light uniformity among a large number of LEDs due to the process of suspending phosphor particles in a carrier. Operator error can cause erroneous mixing resulting in a batch color deviation incident. In addition, the viscosity of the phosphor mixture may change during deposition, or the phosphor suspension may settle over a pot life (pot life) causing a wide range of color bins. In addition, other factors such as chip wavelength, phosphor distribution, substrate reflectivity, etc. may cause variations even when the dispensed (discrete) volume and weight are consistent. The above problems are generally not captured in real time, so it is too late to recover parts and have to be scrapped when they are found during testing. The manufacturing process itself is often time consuming and costly, requiring multiple manufacturing steps to be completed. All these problems lead to an increase in the manufacturing costs of the broad spectrum LED.

There is thus a need in the art for simplified and improved processes for applying phosphor materials to LEDs and other solid state lighting devices.

Disclosure of Invention

In various representative aspects, the present disclosure provides a method of dispensing a phosphor composition onto a light emitting device. According to one example method, a desired characteristic of the light, such as Correlated Color Temperature (CCT) and/or a set of coordinates in a color space (e.g., CIE 1931 color space), and a desired total dispensed volume or weight of the phosphor composition are input into the controller. A first amount of the phosphor composition is dispensed onto a surface of the light emitting device using a plurality of dispensing heads, the dispensing heads including a substantially pure silicone dispensing head for dispensing substantially pure silicone and a plurality of color phosphor dispensing heads each for dispensing a respective color phosphor.

After the first amount of phosphor composition is dispensed, pulsed power is applied to the light emitting device to cause the light emitting device to emit light, which is then detected with a photodetector. The detected characteristic of the light is compared to a desired characteristic, and the relative dispensing of the pure silicone and the at least one colored phosphor is adjusted if necessary to move the detected characteristic toward the desired characteristic. The process is repeated and the dispensing of the phosphor composition is stopped when the detected characteristic of the light is within a predetermined range of the desired characteristic of the light and the amount of phosphor composition on the surface of the light emitting device meets or exceeds the desired total dispensing volume.

In some embodiments, a method of dispensing a phosphor composition onto a light emitting device includes dispensing a portion of the phosphor composition onto the light emitting device. A characteristic of light emitted by the light emitting device is detected, and the relative amounts of the respective portions of the phosphor composition are adjusted to reduce a difference between the detected characteristic of light and a desired characteristic of light.

In some embodiments, a system for dispensing a phosphor composition onto a light emitting device includes a light sensor for detecting a characteristic of light emitted from the light emitting device and a plurality of phosphor dispensers for dispensing respective colors of phosphor and pure silicone onto a surface of the light emitting device. The phosphor and silicone dispenser are adapted to be controlled in response to a detected characteristic of light emitted from the light emitting device.

In some embodiments, a computer readable medium stores a computer program that, when executed by a computer, causes the computer to perform a process for manufacturing a light emitting device. The computer program includes code for dispensing portions of the phosphor composition onto the light emitting device, code for detecting a characteristic of light emitted by the light emitting device, and code for adjusting the relative amounts of the respective portions of the phosphor composition to reduce a difference between the detected characteristic of light and a desired characteristic of light.

These and other aspects of the invention will be more fully understood upon reading this disclosure.

Drawings

The drawings illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a block diagram illustrating a system for dispensing a phosphor composition onto a light emitting device;

FIG. 2 is a flow chart illustrating a process for dispensing a phosphor composition onto a light emitting device; and is

Fig. 3 is a color chart illustrating light characteristics according to the CIE 1931 color space.

The elements and steps in the figures are illustrated for simplicity and clarity and have not necessarily been presented in any particular sequence. For example, steps that may be performed in parallel or in a different order are illustrated in the figures to help improve understanding of embodiments of the present invention.

Detailed Description

In the following detailed description, only certain exemplary embodiments of the present invention are shown and described, by way of illustration. As will be appreciated by those skilled in the art, the present invention may be embodied in many different forms and should not be construed as limited to the examples set forth herein. In addition, in the context of the present disclosure, when an element is referred to as being "on" or "assigned to" another element, "it can be directly on the other element or indirectly on the other element with one or more intervening elements interposed therebetween.

Certain aspects of the invention are described herein in terms of functional block components and various processing steps. Such functional blocks may be realized by any number of hardware or software components configured to perform the specified functions and achieve the various results. For example, a controller is described for performing certain calculations, making decisions, and providing control signals. Such a controller may be implemented in hardware and/or software, and the described functions may be embodied in a computer readable medium storing a computer program that, when executed by a computer, causes the computer to perform the described functions.

Furthermore, the present invention may be practiced in connection with the manufacture of any number of devices in addition to light emitting devices, and the system described is merely one example application for the present invention.

In addition, the present invention may employ any number of conventional techniques for programming control points, sensing light characteristics, calculating and adjusting properties of compositions, and the like.

Like numbers refer to like elements throughout the specification.

Conventional systems and methods for manufacturing light emitting devices with phosphor compositions include premixing phosphor powders in silicone to make phosphor compositions with a predetermined formulation, with the aim of achieving a broad spectrum of "white" light. That is, typical LEDs produce light in a relatively narrow spectrum, while white light is generally desirable for lighting applications. Thus, conventional processes typically include predetermining a formulation for a composition based on knowledge of the properties of the phosphor component of the composition, knowledge of the spectrum of radiation emitted by the LED, and other factors that may affect the emission spectrum, with the goal of complementary additive mixing of the emitted light from the excited phosphor and the LED to produce a perception of white light. This phosphor composition is then deposited on an LED in a predetermined volume and/or weight and cured, and the resulting phosphor-coated LED is then tested. Based on the spectrum measured from each individual LED, the LEDs are typically placed in different bins or categories that separate the devices, e.g., based on Correlated Color Temperature (CCT) and/or a set of coordinates in a color space, such as CIE color space.

Using these conventional processes, it is difficult to achieve consistent optical properties. It is often difficult to maintain light uniformity between LEDs due to the process of suspending phosphor particles in a carrier. Operator error can cause erroneous mixing resulting in a batch color deviation incident. In addition, the phosphor suspension may settle over the pot life or the viscosity of the phosphor mixture may change, resulting in a wide color bin range. In addition, other factors such as chip wavelength, phosphor distribution, substrate reflectivity, etc. may cause variations even when the dispensed volume and weight are consistent. The above problems cannot be captured in real time, so it is too late to recover parts and have to be scrapped when they are found during testing.

A process according to one aspect of the present disclosure avoids many of these and other problems by utilizing feedback during dispensing of the phosphor to dynamically control the relative amount of phosphor composition dispensed onto the light emitting device (such as an LED).

The method and system for manufacturing a light emitting device may operate in conjunction with production system 100. FIG. 1 illustrates a production system 100 according to an example embodiment, which includes a controller 110, a dispenser 120, a sensor 130, a power source 140, and a light emitting device 150.

The controller 110 may be a microprocessor or other computer, a programmable gate array, a dedicated circuit, or any other type of controller having computing, input and output functionality, as well as the ability to execute stored instructions, perform predetermined actions, etc.

The sensor 130 may be an optical sensor or other measurement sensor capable of detecting one or more characteristics of the light emitted by the light emitting device 150, such as the associated color temperature and/or color point (i.e., set of coordinates in color space). For example, sensor 130 may be a Charge Coupled Device (CCD), a colorimeter, or any other suitable sensor known to those skilled in the art. The sensor 130 may include a fiber optic light guide for directing light from the light emitting device toward the sensor. The sensor 130 may send information, such as one or more characteristics of the light, to an input of the controller 110.

The dispenser 120 may be coupled to an output of the controller 110 such that the controller 110 provides a signal to the dispenser 120 to control the dispenser 120. The dispenser may include one or more of a variety of silicone and phosphor dispensers, such as thermal sprayers, piezoelectric sprayers, continuous sprayers, squeeze tubes, syringes, and the like, that may perform a variety of functions. The dispenser 120 may include one or more jetting dispensers for jetting droplets of phosphor of a respective color onto the surface of the light emitting device.

For example, in one exemplary embodiment, the dispenser 120 includes a yellow jet dispenser for dispensing yellow phosphor, a green jet dispenser for dispensing green phosphor, and a red jet dispenser for dispensing red phosphor. In yet another embodiment, a jetting dispenser for dispensing colored phosphors is configured to jet high concentrations (e.g., greater than 30 wt%, approximately 50 wt%, or approximately 80 wt% suspended in a substantially transparent medium, such as silicone) of phosphor powders of their respective colors.

The dispenser 120 may also include a substantially pure silicone dispenser (e.g., a silicone spray head) for dispensing substantially transparent or clear silicone onto the surface of the light emitting device in combination with the colored phosphor dispenser. The dispenser 120 may also include a plurality of reservoirs for storing the concentrated phosphor suspension and the transparent silicone in liquid form for later dispensing.

In some embodiments, each dispenser or each head (e.g., spray head) of the dispenser 120 is configured to dispense droplets of pure silicone or high concentration colored phosphor, respectively, at an individually variable and controllable rate and/or for an individually variable and controllable amount of time to produce a phosphor composition that includes phosphor powder of several colors, pure silicone, and in some embodiments other ingredients. The spray head may dispense droplets in a volume ranging from 1 nanoliter to hundreds of milliliters or may dispense the respective portions of the phosphor composition as a constant flow. The dispensing of the portions of pure silicone and concentrated phosphors of various colors may be offset in time relative to each other or may be at substantially the same time. In addition, the precise location at which each dispenser dispenses its respective portion of the phosphor composition on the surface of the light emitting device may be at the same location or at different locations from one another.

The dispenser 120 may be configured to eject the phosphor composition in at least a partial vacuum. In this manner, the need for degassing and/or mixing of the phosphor composition after dispensing may be reduced or eliminated.

The system as described above reduces or eliminates a separate processing step of mixing the phosphor composition to a predetermined ratio of colored powdered phosphor and silicone, since the respective colors and silicone are "mixed" in situ as they are dispensed, for example, on the surface of the light emitting device. Thus, the ratio of the components of the mixed phosphor composition can be precisely controlled and varied when dispensing the phosphor composition. In addition, the ratio of the components of the mixed phosphor composition may vary from batch to batch or even device to device, but as discussed above, devices and batches may have precisely controlled and consistent color characteristics as other factors besides the phosphor composition may also affect the resulting spectrum.

In addition, the system described above enables the creation of a variously layered or patterned phosphor structure on any surface, including the surface of a light emitting device.

The light emitting device 150 or the stage on which the light emitting device 150 is located may include a heating element 151. The heating element 151 enables curing of the phosphor composition during or immediately after dosing to reduce or eliminate problems associated with settling of the phosphor powder suspension in the silicone. In addition, the heating element achieves control of the viscosity of the phosphor composition, for example, by heating the composition to reduce its viscosity and cause the composition to flow more uniformly and/or more quickly over the surface of the light emitting device 150.

The power supply 140 may supply power to the light emitting device 150. The controller 110 may provide control signals for controlling the power supply 140, or the power supply 140 may operate independently of the controller 110. The power supply 140 may provide a voltage/current to the light emitting device 150 that is constant (DC), Alternating (AC), or pulsed. In embodiments where the power source 140 provides pulsed power, the pulses may be controlled in terms of their amplitude, their high and/or low peak voltage/current, their period, frequency, and/or their duty cycle. In addition, the light emitting device 150 may include one or more light emitting devices, and the power supply 150 may supply power to one or any number of the plurality of light emitting devices. In embodiments where the light emitting device 150 comprises a plurality of light emitting devices, the power supply 150 may provide individually controllable power to one or more (i.e., any subset up to and including all) of the plurality of light emitting devices.

Fig. 2 is a flow chart illustrating an example process of dispensing a phosphor composition onto a light emitting device. The process may be performed by a circuit, a network processor, a computer controlled dispensing system with feedback, or by some other suitable means. For example, the process may be performed by the system of fig. 1.

Referring now to fig. 1 and 2 together, in block 210, a target light characteristic may be input into the system. The input of the target light characteristic may be accomplished by an operator entering one or more desired characteristics of the light emitted by the light emitting device into a user interface, such as a keypad or touch screen interface coupled to the controller 110. The target optical characteristic may be stored in a memory such as a ROM, magnetic storage or EEPROM or in a volatile memory such as a RAM. Some examples of target light characteristics include Correlated Color Temperature (CCT) and color coordinates (e.g., coordinates in color space such as CIEx and CIEy). The one or more target light characteristics input in the system may also include a range, allowing for some tolerance in meeting the target characteristics of the light.

In block 220, a dispense ratio may be set. That is, the dispenser 120 may include a plurality of dispensing heads, some of which may be adapted to dispense colored phosphor. In one example embodiment, three dispensing heads are adapted to dispense red, yellow, or green phosphor, respectively, wherein the red, yellow, or green phosphor may be a high concentration (e.g., greater than about 30%) of phosphor powder suspended in a medium such as silicone. Here, the dispensing ratio corresponds to the relative amounts of the different color phosphors. For example, the dosing ratio may be 2: 1, that is, 2 parts red phosphor to 2 parts yellow phosphor to 1 part green phosphor.

The dispensing ratio may also include a portion of the phosphor composition from a fourth dispensing head in the dispenser 120, including a transparent or clear medium, such as silicone. That is, the dosing ratio may be 2: 1 in one example embodiment, that is, two parts red phosphor to 2 parts yellow phosphor to 1 part green phosphor to 1 part silicone. In some embodiments, the dispensing ratio may be controllable to a very fine degree of precision, and in some embodiments, a small number of different dispensing ratios may be available.

On the other hand, the process according to various example embodiments may forgo the initial setting of the rationing ratio in block 220. That is, in embodiments that include feedback control and automatic correction of the dispense ratio, discussed in more detail below, initialization of the dispense ratio may not be necessary. Thus, the initial dosing ratio may be the same initial value each time the process is run, or the initial dosing ratio may be whatever ratio the system last utilized, or in some embodiments, the initial dosing ratio may be any value.

In block 230, a target amount of the phosphor composition may be set. That is, a predetermined amount (e.g., weight or volume) of the phosphor composition that the dispenser 120 will dispense onto the one or more light emitting devices 150 may be provided to the system. This target amount may be utilized later in the process as a criterion for determining when to end the dispensing of the phosphor composition as described below. The target amount may be preset at the factory, manually entered into the controller 110 by an operator, or loaded from a communication interface coupled to the controller 110.

Skipping block 290, which will be described below, in block 240 the dispenser 120 may dispense portions of the phosphor composition onto the light emitting device 150. The amount of phosphor composition actually dispensed in a particular iteration of block 240 may be controlled and limited to a predetermined amount (e.g., a predetermined weight or volume). The dispenser 120 may also include a heater and/or cooler for controlling the temperature and thus the viscosity of the phosphor composition dispensed onto the light emitting device 150. This enables improved control of the amount dosed in step 240.

Block 240 may also include sub-processes including positioning the light emitting device 150 and/or a dispensing head in the dispenser 120, baking and/or curing the light emitting device 150 by using the heater 151 after dispensing the phosphor composition, or waiting for a period of time after dispensing. In various embodiments including the heater 151 and heating sub-process, rapidly curing the phosphor and/or silicone droplets after dispensing may reduce or eliminate phosphor deposition, thus improving the predictability and consistency of the phosphor distribution and thereby reducing end product variability.

In block 250, power may be applied to the light emitting device 150 (e.g., an LED). For example, a dc voltage may be applied across the two terminals to forward bias the LED to generate current and light emission through the LED. The power may for example be pulsed power, wherein the applied voltage is in the form of a square wave. Here, the light emitted from the LED flickers according to the amplitude, phase, pulse width, frequency and duty ratio of the pulse power. In embodiments including a pulsed power supply, the current driven through the LED may be reduced compared to a DC current, and the heating of the LED is reduced accordingly.

In block 260, light emitted from the light emitting device 150 may be detected. For example, in some embodiments, the sensor 130 senses light and communicates at least one characteristic of the light to the controller 110. The sensor 130 may be in close proximity to the one or more light emitting devices, or the sensor may not be in close proximity, and a light guide (e.g., one or more fiber optic light guides) may be used to direct light from the one or more light emitting devices 150 to the sensor 130. As discussed above, the at least one characteristic of the light may include a relative color temperature and/or a set of coordinates in a color space.

In block 270, the process may determine whether at least one characteristic of the light detected in block 260 is at or near the target characteristic set in step 210. That is, the controller 110 may perform a comparison between the detected characteristics determined by the sensor 130 and the target characteristics input into the controller 110. The comparison may be performed with a hardware comparator, a difference amplifier, or software. Additionally, the target for comparison may include a hard threshold, or the comparison may be weighted according to a number of factors, including but not limited to the amount of phosphor composition that has been dispensed.

If the comparison of the detected characteristic to the target characteristic is not a good result, that is, if the light deviates from the target or the difference between the detected characteristic and the target characteristic is greater than a predetermined threshold, the process may branch to block 280. If, however, the comparison of the detected characteristic to the target characteristic is good, that is, the light is on the target or the difference between the detected characteristic and the target characteristic is less than the predetermined threshold, the process may branch to block 290.

In block 280, the process may adjust the dosing ratio. For example, the controller 110 may send instructions to the dispenser 120 to adjust the relative amounts of concentrated colored phosphor suspension and/or clear silicone to "move" the characteristics of the light emitted from the light emitting device "closer" to the target characteristics.

For example, fig. 3 is a graphical representation of the international commission on illumination (CIE)1931 color space known to those skilled in the art. This color space is a plot of the entire human perceptible color gamut according to a set of coordinates (i.e., CIEx and CIEy coordinates). Line 320 shows the color coordinates of the black body radiator at the noted temperature (i.e., color temperature). In one example embodiment, the target characteristic of the light is a correlated color temperature of approximately 3100K or in another embodiment the set of coordinates CIEx 0.4 ± 0.001 and CIE y 0.4 ± 0.001. As an example, assume that at block 260, the detected light includes the coordinate sets CIE x-0.2 and CIE y-0.1. At block 270, the process determines that the detected light deviates from the target, so the process branches to block 280 and adjusts the dosing ratio. That is, the relative amounts of the red, green and yellow phosphors and the transparent silicone are adjusted so as to move the color coordinates toward the target coordinates.

In an example embodiment, the adjustment of the dispense ratio may be adjusted based on the position of the detected characteristic relative to the color temperature line 320. For example, if the detected characteristic is below the color temperature line 320, the adjusting may include increasing the proportion of the green phosphor. If the detected characteristic is above the color temperature line 320, the adjusting may include increasing the proportion of red phosphor. Similarly, increasing the proportion of yellow phosphor may shift the light characteristics along the color temperature line in a direction that reduces the color temperature.

If the process determines at block 270 that the light is sufficiently on the target, the process may branch to block 290. In block 290, the process may determine whether the total amount of phosphor composition dispensed onto the light emitting device meets or exceeds the target amount set in block 230. In various embodiments, this determination may be made by controller 110, dispenser 120, or another device coupled to light emitting device 150. Note that various embodiments may make the determination based on the ration amount being equal to (═ to), greater than (>) or greater than or equal to (≧) the target amount or based on other suitable relationships between the ration amount and the target amount. If the target amount has been reached, the process may end. Otherwise, the process may branch to block 240 to perform another iteration (including dispensing phosphor, measuring a characteristic of light, and possibly adjusting a dispensing ratio).

Those skilled in the art will appreciate that the process shown in fig. 2 is only one example of a process within the scope of the present disclosure and that variations and modifications may be made without departing from the intended scope. For example, another process may add another step after block 280 or at any other intermediate step within the process to determine whether the total amount of phosphor composition meets and/or exceeds the target amount.

Additionally, the order or sequence of steps described is not necessarily the only possible implementation. For example, in some aspects, applying power to the light emitting device and detecting a characteristic of the light are performed continuously in parallel with dispensing the phosphor composition onto the light emitting device. In certain aspects, applying power and detecting the characteristics of light are done discontinuously, nor in any particular sequence, but periodically (e.g., from every 100ms to every 1 minute) while dispensing the phosphor composition onto the light emitting device, but independently of the timing of other process steps.

By using a process according to the above description, the characteristics of the light emitted by a phosphor coated light emitting device can be more accurately controlled to ensure that a large number of devices will emit light with low variability in color point or other characteristics, thus reducing or eliminating the need for binning and increasing throughput. In addition, the necessity of pre-mixing the phosphor composition is reduced or eliminated, thereby reducing production costs.

In the foregoing specification, the invention has been described with reference to various exemplary embodiments. Various modifications and changes may be made without departing from the scope of the invention as set forth in the claims and their equivalents. The specification and figures are to be regarded in an illustrative rather than a restrictive sense, and modifications are intended to be included within the scope of present invention. The scope of the invention should, therefore, be determined only by the claims and their legal equivalents, rather than by merely the examples described.

For example, the steps recited in any method or process claims may be executed in any order and are not limited to the specific order presented in the claims. Furthermore, the components and/or elements recited in any apparatus claims may be assembled or otherwise operationally configured in a variety of permutations and are therefore not limited to the specific configuration recited in the claims.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments; however, any benefit, advantage, solution to problem or any element that may cause any particular benefit, advantage or solution to occur or to become more pronounced are not to be construed as a critical, required or essential feature or component of any or all the claims.

As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "including," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, composition or apparatus that comprises a list of elements does not include only those elements recited, but may include other elements not expressly listed or inherent to such process, method, article, composition or apparatus. Other combinations and/or modifications of the above-described structures, arrangements, applications, proportions, elements, materials or components used in the practice of the present invention, in addition to those not specifically recited, may also be varied or otherwise particularly adapted to specific requirements, manufacturing specifications, design parameters or other operating requirements without departing from the general principles of the same.

The previous description is provided to enable others skilled in the art to fully understand the full scope of the disclosure. Modifications to the various configurations disclosed herein will be readily apparent to those skilled in the art. Thus, the claims are not intended to be limited to the various aspects of the disclosure described herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". Unless otherwise indicated, the term "some" refers to one or more, claims reciting at least one element of a combination of elements (e.g., "A, B or at least one of C"), refers to one or more of the recited elements (e.g., a or B or C, or any combination thereof). All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. Unless the phrase "for an.

Claims (53)

1. A method of dispensing a phosphor composition onto a light emitting device, comprising:

a portion onto the light emitting device that dispenses the phosphor composition;

detecting a characteristic of light emitted by the light emitting device; and is

Adjusting the relative amounts of the respective portions of the phosphor composition to reduce the difference between the detected characteristic of the light and the desired characteristic of the light.

2. The method of claim 1, wherein the desired characteristic of the light comprises at least one of a Correlated Color Temperature (CCT) or a set of coordinates in color space.

3. The method of claim 2, wherein the desired characteristics of the light comprise the CCT and a set of coordinates in the color space.

4. The method of claim 1, wherein the respective portions of the phosphor composition comprise respective colors of phosphors suspended in silicone.

5. The method of claim 4, wherein the dispensing of the phosphor composition comprises dispensing phosphor of each respective one of the colors with a respective one of a plurality of dispensers.

6. The method of claim 5, wherein each dispenser of the plurality of dispensers comprises a jetting dispenser.

7. The method of claim 5, wherein each of the plurality of dispensers is adapted to dispense greater than about 30 wt% suspension of its respective color phosphor powder in silicone.

8. The method of claim 5, wherein the plurality of dispensers includes a red phosphor dispenser, a green phosphor dispenser, and a yellow phosphor dispenser.

9. The method of claim 5, wherein the adjusting of the relative amounts of the respective portions of the phosphor composition comprises controlling a dispensing time and/or speed of each of the respective dispensers.

10. The method of claim 4, wherein the respective portion of the phosphor composition further comprises substantially pure silicone.

11. The method of claim 10, wherein the dispensing of the phosphor composition comprises dispensing the substantially pure silicone with a silicone dispenser.

12. The method of claim 10, further comprising ending the dispensing of the phosphor composition when the detected characteristic of the light is within a predetermined range of a desired characteristic of the light.

13. The method of claim 12, further comprising ending the dispensing of the phosphor composition when a predetermined volume or a predetermined weight of the phosphor composition has been dispensed.

14. The method of claim 1, further comprising applying power to the light emitting device to emit light.

15. The method of claim 14, wherein the power applied to the light emitting device is suitable for testing the light emitting device under pulsed conditions.

16. An apparatus operable in a light emitting device manufacturing system, the apparatus comprising:

means for dispensing the phosphor composition onto the light emitting device;

means for detecting a characteristic of light emitted by the light emitting device; and

means for adjusting the relative amounts of the respective portions of the phosphor composition to reduce the difference between the detected characteristic of the light and the desired characteristic of the light.

17. The apparatus of claim 16, wherein the desired characteristic of the light comprises at least one of a Correlated Color Temperature (CCT) or a set of coordinates in a color space.

18. The apparatus of claim 17, wherein the desired characteristics of the light comprise the CCT and the set of coordinates in the color space.

19. The device of claim 16, wherein the respective portions of the phosphor composition comprise respective colors of phosphors suspended in silicone.

20. The device of claim 19, wherein the means for dispensing a phosphor composition comprises means for dispensing a phosphor of each respective one of the colors with a respective means for dispensing a phosphor of a respective color.

21. The device of claim 20, wherein each of the respective means for dispensing color phosphor comprises a jetting dispenser.

22. The apparatus of claim 20, wherein each of said respective means for dispensing color phosphor is adapted to dispense greater than about 30 wt% suspension in silicone of its respective color phosphor powder.

23. The device of claim 20, wherein the respective means for dispensing a respective color of phosphor comprises means for dispensing a red phosphor, means for dispensing a green phosphor, and means for dispensing a yellow phosphor.

24. The apparatus of claim 20, wherein the means for adjusting the relative amounts of the respective portions of phosphor composition comprises means for controlling the dosing time and/or speed of each of the means for dosing the color phosphor.

25. The device of claim 19, wherein the respective portion of the phosphor composition further comprises substantially pure silicone.

26. The device of claim 25, wherein the means for dispensing a phosphor composition comprises means for dispensing the substantially pure silicone.

27. The device of claim 26, further comprising means for ending the dispensing of the phosphor composition when the detected characteristic of the light is within a predetermined range of a desired characteristic of the light.

28. The apparatus of claim 27, further comprising means for ending the dispensing of the phosphor composition when the amount of the phosphor composition dispensed meets or exceeds at least one of a predetermined volume or a predetermined weight.

29. The apparatus of claim 16, further comprising means for applying power to the light emitting device to emit light.

30. The apparatus of claim 29, wherein the means for applying power to the light emitting device is configured to test the light emitting device under pulsed conditions.

31. A system for dispensing a phosphor composition onto a light emitting device, comprising:

a light sensor for detecting a characteristic of light emitted from the light emitting device; and

a plurality of phosphor dispensers, each for dispensing a respective color of phosphor onto a surface of the light emitting device,

Wherein the phosphor dispenser is adapted to be controlled in response to a detected characteristic of the light emitted from the light emitting device.

32. The system of claim 31, wherein the phosphor dispenser is further configured to adjust a ratio of phosphors of the respective colors to dynamically reduce a difference between the detected characteristic of the light and the desired characteristic of the light while dispensing the respective portion of the phosphor composition.

33. The system of claim 32, wherein the phosphor dispenser is further configured to dynamically adjust a dispensing time and/or speed while dispensing a respective portion of the phosphor composition to reduce the difference between the detected characteristic of the light and the desired characteristic of the light

34. The system of claim 32, wherein the detected characteristic of the light comprises at least one of a Correlated Color Temperature (CCT) or a set of coordinates in a color space.

35. The system of claim 34, wherein the detected characteristics of the light comprise the CCT and a set of coordinates in the color space.

36. The system of claim 31, further comprising a silicone dispenser for dispensing substantially pure silicone onto a surface of the light emitting device.

37. The system of claim 36, wherein the phosphor dispenser and the silicone dispenser each respectively comprise a spray head for spraying phosphor of a respective color or substantially pure silicone.

38. The system of claim 36, wherein the phosphor dispenser is further configured to stop dispensing phosphor and substantially pure silicone when the dispensed amount of the phosphor composition meets or exceeds a predetermined target amount, or when the detected characteristic of the light is within a predetermined range of the desired characteristic of the light.

39. A computer-readable medium storing a computer program which, when executed by a computer, causes the computer to perform a process for manufacturing a light emitting device, the computer program comprising:

code for dispensing a portion of the phosphor composition onto the light emitting device;

code for detecting a characteristic of light emitted by the light emitting device; and

code for adjusting relative amounts of respective portions of the phosphor composition to reduce a difference between the detected characteristic of the light and the desired characteristic of the light.

40. The computer readable medium of claim 39, wherein the desired characteristic of the light comprises at least one of a Correlated Color Temperature (CCT) or a set of coordinates in a color space.

41. The computer readable medium of claim 40, wherein the desired characteristics of the light include the CCT and the set of coordinates in the color space.

42. The computer readable medium of claim 39, wherein the respective portions of the phosphor composition comprise respective colors of phosphors suspended in silicone.

43. The computer-readable medium of claim 42, wherein the code for dispensing the phosphor composition comprises code for dispensing phosphor of each respective one of the colors with a respective one of a plurality of phosphor dispensers.

44. The computer readable medium of claim 43, wherein each of the phosphor dispensers comprises a jetting dispenser.

45. The computer readable medium of claim 43, wherein each of the phosphor dispensers is adapted to dispense greater than about 30 wt% suspension of its respective color phosphor powder in silicone.

46. The computer readable medium of claim 43, wherein the phosphor dispenser comprises a red phosphor dispenser, a green phosphor dispenser, and a yellow phosphor dispenser.

47. The computer-readable medium of claim 43, wherein the code for adjusting the relative amounts of the respective portions of the phosphor composition comprises code for controlling a dispensing time and/or speed of each of the phosphor dispensers.

48. The computer readable medium of claim 42, wherein the respective portion of the phosphor composition further comprises substantially pure silicone.

49. The computer-readable medium of claim 48, wherein the code for dispensing a phosphor composition comprises code for dispensing the substantially pure silicone.

50. The computer readable medium of claim 39, further comprising code for ending dosing of the phosphor composition when the detected characteristic of the light is within a predetermined range of a desired characteristic of the light.

51. The computer readable medium of claim 50, further comprising code for ending the dispensing of the phosphor composition when the amount of the phosphor composition dispensed meets or exceeds at least one of a predetermined volume or a predetermined weight.

52. The computer-readable medium of claim 39, further comprising code for applying power to the light emitting device to emit light.

53. The computer-readable medium of claim 52, wherein the code for applying power to a light emitting device comprises code for testing the light emitting device under pulsed conditions.