Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – Encapsulated
Reexamination Certificate
2001-04-13
2003-02-18
Abraham, Fetsum (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
Encapsulated
C257S098000, C257S099000, C257S678000
Reexamination Certificate
active
06521916
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to radiation emitter devices such as, for example, light emitting diode (LED) packages, to methods of making radiation emitter devices, and to opto-electronic emitter assemblies incorporating optical radiation emitter devices.
As used herein, the term “discrete opto-electronic emitter assembly” means packaged radiation emitter devices that emit ultraviolet (UV), visible, or infrared (IR) radiation upon application of electrical power. Such discrete opto-electronic emitter assemblies include one or more radiation emitters. Radiation emitters, particularly optical radiation emitters, are used in a wide variety of commercial and industrial products and systems, and accordingly come in many forms and packages. As used herein, the term “optical radiation emitter” includes all emitter devices that emit visible light, near IR radiation, and UV radiation. Such optical radiation emitters may be photoluminescent, electroluminescent, or another type of solid state emitter. Photoluminescent sources include phosphorescent and fluorescent sources. Fluorescent sources include phosphors and fluorescent dyes, pigments, crystals, substrates, coatings, and other materials.
Electroluminescent sources include semiconductor optical radiation emitters and other devices that emit optical radiation in response to electrical excitation. Semiconductor optical radiation emitters include light emitting diode (LED) chips, light emitting polymers (LEPs), organic light emitting devices (OLEDs), polymer light emitting devices (PLEDs), etc.
Semiconductor optical emitter components, particularly LED devices, have become commonplace in a wide variety of consumer and industrial opto-electronic applications. Other types of semiconductor optical emitter components, including OLEDs, LEPs, and the like, may also be packaged in discrete components suitable as substitutes for conventional inorganic LEDs in many of these applications.
Visible LED components of all colors are used alone or in small clusters as status indicators on such products as computer monitors, coffee makers, stereo receivers, CD players, VCRs, and the like. Such indicators are also found in a diversity of systems such as instrument panels in aircraft, trains, ships, cars, trucks, minivans and sport utility vehicles, etc. Addressable arrays containing hundreds or thousands of visible LED components are found in moving-message displays such as those found in many airports and stock market trading centers and also as high brightness large-area outdoor television screens found in many sports complexes and in some urban billboards.
Amber, red, and red-orange emitting visible LEDs are used in arrays of up to 100 components in visual signaling systems such as vehicle center high mounted stop lamps (CHMSLs), brake lamps, exterior turn signals and hazard flashers, exterior signaling mirrors, and for roadway construction hazard markers. Amber, red, and blue-green emitting visible LEDs are increasingly being used in much larger arrays of up to 400 components as stop/slow/go lights at intersections in urban and suburban intersections.
Multi-color combinations of pluralities of visible colored LEDs are being used as the source of projected white light for illumination in binary-complementary and ternary RGB illuminators. Such illuminators are useful as vehicle or aircraft maplights, for example, or as vehicle or aircraft reading or courtesy lights, cargo lights, license plate illuminators, backup lights, and exterior mirror puddle lights. Other pertinent uses include portable flashlights and other illuminator applications where rugged, compact, lightweight, high efficiency, long-life, low voltage sources of white illumination are needed. Phosphor-enhanced “white” LEDs may also be used in some of these instances as illuminators.
IR emitting LEDs are being used for remote control and communication in such devices as VCR, TV, CD and other audio-visual remote control units. Similarly, high intensity IR-emitting LEDs are being used for communication between IRDA devices such as desktop, laptop, and palmtop computers; PDAs (personal digital assistants); and computer peripherals such as printers, network adapters, pointing devices (“mice,” trackballs, etc.), keyboards and other computers. IR LED emitters and IR receivers also serve as sensors for proximity or presence in industrial control systems, for location or orientation within such opto-electronic devices such as pointing devices and optical encoders, and as read heads in such systems as barcode scanners. IR LED emitters may also be used in a night vision system for automobiles.
Blue, violet, and UV emitting LEDs and LED lasers are being used extensively for data storage and retrieval applications such as reading and writing to high-density optical storage disks.
For discrete LED devices and other discrete (“packaged”) opto-electronic emitters, increased performance is dependent substantially upon increased reliable package power capacity, reduced package thermal resistance, and reduced susceptibility of the package to damage during auto-insertion, soldering and other circuit or system manufacturing operations.
Keeping discrete opto-electronic emitters cool during operation enhances performance in several ways. The efficiency of the emitter usually decreases in relation to increased operating temperature and increases in relation to reduced operating temperature. Conversely, emitter efficiency typically increases in relation to reduced internal operating temperature. The reliability of the emitter and life of the materials and sub-components comprising it usually improves in relation to decreased operating temperature. The consistency of the emitter's emission spectra is usually improved in relation to decreased or more consistent operating temperature. The decay life of the emitter is usually improved in relation to reduced operating temperature. For these and other reasons, it is clearly beneficial to employ novel mechanisms for reducing the operating temperature of discrete opto-electronic emitters.
While the ambient environmental temperature is an external factor that cannot always be controlled, the temperature rise of the device above the ambient temperature is determined mainly by the device's thermal resistance and operating power.
Unfortunately, most discrete opto-electronic emitters exhibit a characteristic contravening to the goal of reduced internal operating temperature. In short, these types of devices usually emit greater amounts of useful radiation in proportion to increased power up to some practical limit of the package or constituent materials or subcomponents. Thus, for applications where more radiation is useful (i.e., almost all applications known), it is beneficial to drive the device at the highest power consistent with device and system reliability and consistent with the power-radiation characteristics of the device. However, increased power in devices with finite (positive, non-zero) thermal resistance results in elevated internal operating temperatures.
It would be advantageous then to reduce internal operating temperature without having to reduce device power, or alternately to maintain internal operating temperature while increasing device power. This can be accomplished by reducing the device thermal resistance.
Billions of LED components are used in applications such as those cited above, in part because relatively few standardized LED configurations prevail and due to the fact that these configurations are readily processed by the automated processing equipment used almost universally by the world's electronic assembly industries. Automated processing via mainstream equipment and procedures contributes to low capital cost, low defect rates, low labor cost, high throughput, high precision, high repeatability and flexible manufacturing practices. Without these attributes, the use of LEDs becomes cost prohibitive or otherwise unattractive from a quality standpoint for most high-volume applications.
T
Reese Spencer D.
Roberts John K.
Abraham Fetsum
Andujar Leonardo
Gentex Corporation
Price Heneveld Cooper DeWitt & Litton
LandOfFree
Radiation emitter device having an encapsulant with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Radiation emitter device having an encapsulant with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiation emitter device having an encapsulant with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3136488