WO2005103555A1

WO2005103555A1 - A fluorescent bulb replacement with led system

Info

Publication number: WO2005103555A1
Application number: PCT/US2005/012782
Authority: WO
Inventors: Mathew Sommers
Original assignee: Gelcore Llc
Priority date: 2004-04-15
Filing date: 2005-04-15
Publication date: 2005-11-03

Abstract

A light-emitting diode-based light source (26) for retrofitting into a fluorescent lamp (10) employing a fluorescent light bulb (14) includes at least one LED (32), and electrical contact pins (40) adapted to mate with connections (24) of a fluorescent lamp ballast (20). The pins (40) are directly plugged into the bi-pin connections (24).

Description

A FLUORESCENT BULB REPLACEMENT WITH LED SYSTEM

This application claims the benefit of U.S. provisional application Serial No. 60/562,612, filed on April 15, 2004, which is incorporated by reference herein.

BACKGROUND The application relates to the lighting arts. It is especially applicable to the retro-fitting of fluorescent light systems with a more durable light emitting diode (LED)-based light source, and will be described with particular reference thereto. However, the invention will also find application in numerous original equipment applications including lamps, flashlights, and other illuminators which presently employ fluorescent light bulbs that have high failure rates principally due to the fluorescent tube damage or malfunction. The invention provides LED-based light sources which are safe and have improved versatility and excellent compatibility with existing lighting standards. Typically, fluorescent light bulb packages have a light source that includes a fluorescent tube within a glass enclosure. Fluorescent lights suffer from some disadvantages. The bulb occasionally fails, usually due to the fluorescent tube failure. Bulb replacement is inconvenient and cumbersome. LEDs present an attractive and reliable alternative as potential light source in a fluorescent light bulb package. LED light's life is typically up to 100,000 hours, e.g. eleven years. This greatly exceeds the life of a typical fluorescent light bulb. LEDs are about twice as efficient as fluorescent lamps. In addition to such obvious advantages as low power and energy efficiency, LEDs are solid state devices with no moving parts which are not easily damaged by shock or vibration. Furthermore, LEDs characteristics do not change significantly over time. However, retro-fitting the fluorescent lighting systems with an LED- based light bulb is complicated because of different electrical and optical characteristics of the LED versus the fluorescent light source. Existing fluorescent based hardware and power supplies need to be removed if an LED based lighting design were to be employed. The presently employed retro-fit methods require extensive re-wiring of the electrical connections, negating the convenience, simplicity, and speed of conventional light bulb replacement. The present application contemplates a new method and apparatus that reduces the above-mentioned problems and others.

BRIEF SUMMARY In accordance with one aspect, a method for retro-fitting a fluorescent light with an LED light source is disclosed. The fluorescent light includes a fluorescent bulb and a ballast. The LED light source includes at least one LED disposed on a platform. The fluorescent light bulb is removed from the ballast. The LED light source is connected into the ballast by inserting contact pins disposed about the LED light source into connections provided in the ballast. In accordance with another aspect, an LED light source for retrofitting into a fluorescent lamp fixture employing a fluorescent light bulb and a fluorescent lamp ballast is disclosed. The LED light source comprises at least one LED and a platform on which the at least one LED is disposed. Contact pins, which are disposed about the LED light source, provide electrical power to the at least one LED when inserted into connections of the fluorescent lamp ballast. One advantage of the present application resides in a direct replacement of a fluorescent bulb with an LED light source by a use of bi-pin connections. Numerous other advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS The application may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating some embodiments and are not to be construed as limiting the application. FIGURE 1 shows a traditional fluorescent light; FIGURES 2 and 3 show an LED light for retro-fitting into a fluorescent light package in accordance with the present application; and FIGURE 4 shows a method of retro-fitting a fluorescent light with an

LED light.

DETAILED DESCRIPTION With reference to FIGURE 1 , a traditional fluorescent lamp 10 includes a base 12 and a fluorescent bulb 14. A glass envelope 16 is typically covered with phosphor and encompasses the fluorescent light elements such as lamp's electrode (not shown). Contact pins 18 are disposed on the base 12 in operative connection with the electrode. A ballast 20 includes all necessary hardware such as power electronics and power supply 22 to power up the fluorescent bulb 14. Bi-pin connections or grooves 24 are disposed on a first side of the ballast 20, proximate to the base 12, to cooperate with the contact pins 18 to supply the electric power to the fluorescent bulb 14. The connections 24 are disposed on the opposite sides of the first side of the ballast 20 extending in a longitudinal direction and away from the base 12. The connections 24 are connected with the power supply which supplies power to the fluorescent bulb 14 when the connections 24 are in contact with the pins 18. With reference to FIGURES 2 and 3, an LED light source 26 replaces the fluorescent bulb 14. The ballast 20 and the associated fluorescent lamp hardware are physically and, preferably, functionally retained. The LED light 26 includes an LED assembly 28 and an envelope or cover 30. LEDs 32 of the LED assembly 28 are disposed on a mounting or first surface 34 of a heat conductive platform 36. The heat conductive platform 36 improves the air flow around the LED assembly 28 to increase the lifetime of the LED light 26. To facilitate more efficient heat dissipation, the heat conductive platform 36 includes a heatsink 38 which is disposed in thermal communication with the LEDs 32. The platform 36 preferably includes a printed circuit board or an interconnect board or interconnect boards which embodiment includes circuitry for powering the LEDs 32. The mounting surface 34 of the platform 36 is preferably manufactured from a highly reflective material. In one embodiment, the mounting surface 34 is coated with a reflective material leaving the openings for the emitters. Electrical connectors or pins 40 are disposed about the light source 26 to plug directly into the fluorescent bi-pin connections 24. The electrical connectors 40 extend in a longitudinal direction parallel to one another and away from the light source 26. The electrical connectors 40 can be shaped to be easily inserted into the connections 24. For example, the electrical connectors 40 can be rounded, V-shaped, or any other appropriate shape to cooperate with the connections 24 for easier insertion. The LEDs 32 operate at a low DC voltage and draw few milliamperes of electric current. Preferably, the LED light source 26 includes electric power conditioning electronics and/or power supply 42 to convert standard fluorescent ballast voltage to the appropriate LED voltage. Alternatively, power can be delivered to the LED light source 26 by means of other power supply systems. For example, the electrical connectors 40 can be attached to flexible circuits, e.g. copper traces on a flexible material. The flexible circuits can be connected to one another by wires, electrical jumpers, or the like. The LEDs 32 are attached to the platform 36 in arrays or strips. In one embodiment, in which the packaged LEDs are used, the LEDs 32 are soldered, adhered by use of a conductive adhesive, or otherwise conductively fastened to the platform 36. In another embodiment, in which the chip LEDs or LEDs on sub-mounts are used, the LEDs 32 are directly attached to the platform 36 by use of a thermally conductive adhesive. The envelope 30 is a light transmissive cover and is disposed over the LED assembly 28. Optionally, a phosphor 44 is disposed on an inside surface 46 of the envelope 30. If provided, the phosphor is selected to produce a desired wavelength conversion of a portion or substantially all of the light produced by the light emitting diodes 32. The phosphor can include a single phosphor compound or blends of two or more chemically distinct individual compounds chosen to produce a selected wavelength conversion. In one embodiment, the LEDs 32 are blue, violet, or ultra-violet emitters such as Group Ill-nitride LEDs, and the phosphor converts most or substantially all of the light generated by the LEDs 32 into white light. In another embodiment, the LEDs 32 are blue LEDs such as Group Ill-nitride LEDs, and the phosphor is a yellow phosphor that converts some of the blue light into yellow light. Green, blue light and yellow phosphor generated light combine to produce white light. These are examples only and substantially any conversion of light produced by the LEDs 32 can be performed by suitable selection of the LEDs outputting light at the selected wavelengths and suitable selection of the phosphor. With continuing reference to FIGURE 2, the LEDs 32 are disposed on generally planar mounting surface 34 of the heat conductive platform 36. In one embodiment, the platform 36 is generally cylindrical. The mounting surface 34 is generally parallel to a second surface 48 which is disposed opposing the mounting surface 34. The mounting and second surfaces 34, 48 define the platform perimeter. The electrical connectors 40 are preferably disposed about the perimeter of the platform 36, on the second surface 48, opposing one another and extend in a longitudinal direction parallel to one another and away from the platform 36 to plug directly into the fluorescent bi-pin connections 24. The envelope 30 has an open end 50 defining an envelope perimeter that connects with the platform 36. In one embodiment, the platform 36 includes an annular groove (not shown) that receives the perimeter of the envelope 30 which, in this embodiment, is a hemispherical cover. Of course, other shapes of the cover are also contemplated. In some embodiments, the annular groove is omitted, in which case, the placement of the cover 30 on the platform 36 is positioned by other means, such as by using an automated assembly jig. With reference again to FIGURE 3, the envelope 30 is a tubular shaped cover. The ballast 20 includes first and second ballast portions 20-ι, 20₂. The first and second ballast portions 20ι, 20₂ each includes respective first and second pairs 24ι, 24₂ of bi-pin connections. The platform 36 is disposed longitudinally about a central axis 52 of the tubular envelope 30. In one embodiment, the platform 36 is a flat platform with the LEDs 32 positioned on the first and second opposing surfaces 34, 48. In another embodiment, the platform 36 is a circular platform with the LEDs 32 positioned around the circular surface. The envelope 30 is terminated with first and second side surfaces 54, 56, which are disposed opposing each other and define the envelope perimeter. The pins 40 include first and second pairs 40ι, 40₂ of pins. The first and second pairs 40ι, 40₂ of pins are positioned about the envelope perimeter, on respective first and second side surfaces 54, 56 of the envelope 30 to plug directly into respective first and second pairs 24ι, 24₂ of connections. With continuing reference to FIGURE 3 and further reference to

FIGURE 4, a suitable method 60 for retro-fitting the fluorescent light 10 with the LED light source 26 is shown. In a step 62, the fluorescent bulb 14 is removed from the ballast 20. In a step 64, the LED light source 26 is inserted into the bi-pin connections 24 of the ballast 20. The method 60 preferably does not involve removal or replacement of the fluorescent light power supply 22 or any other existing hardware component of the fluorescent lamp ballast 20 except the light bulb 14. In the event of a future failure of the LED-based lamp, it can be replaced by another LED-based lamp. Alternatively, the lamp can be re-fitted with a fluorescent light bulb, by simply removing the LED light source 26 and re-installing a fluorescent light bulb into the ballast 20. The fluorescent bulb replacement has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

WHAT IS CLAIMED IS:

1. A method for retro-fitting a fluorescent light (10) which includes a fluorescent bulb (14) and a fluorescent light ballast (20) with an LED light source (26) which includes at least one LED (32) disposed on a platform (36), the method comprising: removing the fluorescent light bulb (14) from the ballast (20); and connecting the LED light source (26) into the ballast (20), including inserting contact pins (40), which are disposed about the LED light source, into connections (24) provided in the fluorescent light ballast (20).

2. The method of claim 1 , wherein the connections are grooves which are disposed proximate to the LED light source.

3. The method of claim 2, wherein the grooves extend in a longitudinal direction and away from the LED light source.

4. The method of claim 1 , wherein the contact pins extend in a longitudinal direction and away from the LED light source.

5. The method of claim 1, wherein insertion portions of the contact pins are shaped for easy insertion into the connections.

6. The method of claim 1 , wherein the contact pins are shaped to match shape of the connections.

7. The method of claim 6, wherein the contact pins are shaped to at least one of rounded shape and V shape.

8. The method of claim 1 , wherein the step of connecting includes: connecting into existent fluorescent power supply.

9. The method of claim 1, wherein the LED light source is at least one of: a hemispherical shape; and a tubular shape.

10. An LED light source (26) for retro-fitting into a fluorescent lamp fixture employing a fluorescent light bulb (14) and a fluorescent lamp ballast (20), the LED light source comprising: at least one LED (32); a platform (36), on which the at least one LED is disposed; and contact pins (40), which are disposed about the LED light source (26), for providing electrical power to the at least one LED (32) when inserted into connections (24) of the fluorescent lamp ballast (20).

11. The light source of claim 10, wherein the connections (24) are grooves which are disposed proximate to the LED light source (26).

12. The light source of claim 11, wherein the grooves extend in a longitudinal direction and away from the LED light source (26).

13. The light source of claim 10, wherein the contact pins (40) extend in a longitudinal direction and away from the LED light source (26).

14. The light source of claim 10, wherein insertion portions of the contact pins (40) are shaped for easy insertion into the connections (24).

15. The light source of claim 10, wherein the contact pins (40) are shaped to match shape of the connections (24).

16. The light source of claim 15, wherein the contact pins (40) are shaped to at least one of rounded shape and V shape.

17. The light source of claim 10, wherein the ballast (20) includes: a fluorescent light power supply (22).

18. The light source of claim 17, further including: a conversion circuit (42) for converting the power supplied by the fluorescent light power supply (22) to DC power.

19. The light source of claim 10, further including: a light transmissive cover which encompasses the at least one LED (32) and is at least one of: a hemispherical shape; and a tubular shape.