APPARATUS FOR MAGNETIZATION

FIELD OF INVENTION

[0001] The present invention relates to a light emitting device and more particularly to a light emitting diode having an improved heat sink arrangement.

BACKGROUND OF INVENTION

[0002] A conventional Light Emitting Diodes hereinafter referred to as LEDs are a very energy efficient electronic lighting source. The first generation of LEDs emitted red light with a very small amount of illuminating power. However, modern LEDs can now generate light across the visible, ultraviolet, and infrared wavelengths. LED's are currently used as replacements for incandescent light bulbs and fluorescent lamps. In comparison to incandescent lighting (based on filament heating), LED based lighting systems are much more efficient at converting electric power to light energy and in comparison to fluorescent lighting (based on absorption or reemission of photons generated by a plasma), LED based lighting systems have longer lifetimes, operate without noticeable flickering and humming and do not require high voltage electronics.

[0003] Efficient removal of heat is important in LED based lighting systems. Despite its efficiency, heat is generated by an LED during operation, and concentrates in a small volume potentially increasing the LED's operating temperature significantly. The operating lifetime of an LED is often strongly correlated to its operating temperature and a small increase in operating temperature may degrade operating lifetime by hundreds or thousands of hours.

[0004] Dissipation of the heat generated by the LED is generally managed through the substrate on to which it is mounted or through an additional metal heat sink below the substrate and then to an outer heat sink. For LED's mounted on a Printed Circuit Board (PCB) having a dielectric core, the dielectric medium acts as a bottleneck for heat transfer due to its low thermal conductivity. An alternate approach is to use a PCB comprising a metal core. While metal core PCB's are effective for dissipating heat, disadvantages are increased cost and processing difficulties. In addition, since there are limitations to the size of metal core PCB's, they are more difficult to incorporate into larger size devices.

[0005] Another approach for dissipating heat from LED is to attach the LED directly to a heat sink using a thermally conductive adhesive or tape. A disadvantage of this approach is that it is a labor-intensive process resulting in increased costs and manufacturing time. Further, the resulting configuration is subject to high failure rates.

[0006] Therefore to obviate defects in the prior art, there is required a light emitting diode device with a heat sink arrangement which provides highly efficient and timely dissipation of heat generated by the LED and this forms the principal objective of the present invention. It is a further objective of the present invention to provide a light emitting diode device, which has a cost effective heat sink arrangement.

SUMMARY OF THE INVENTION

[0007] The invention discloses a method to dissipate the heat generated during operating of an LED by using more effective heat dissipating techniques. In the current invention, the thermal slug attached to the die of the semi-conductor wafer is being designed to have fins, which increase the surface area of the thermal slug thereby increasing the effective are of the thermal slug, which also acts as a thermal heat sink thus helping in the heat dissipation.

[0008] Apart from using the fins on the thermal slug, the thermal slug is also designed to have a shape of screw with threads. The threads in the thermal slug also increase the effective area of the thermal slug a compared to the thermal slug, which is plain. Apart from increasing the surface area in the case when the thermal slug is made to have threads, it also provides a better fastening mechanism for the fastening of the thermal slug into the outer heat sink.

BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 Shows a typical apparatus for magnetization of a material.

[00010] Figure 2 Shows the setup for magnetization process.

[00011] Figure 3 Illustrates removal of material after magnetization.

[00012] Figure 4 Illustrates the magnetic flux linkage within the apparatus.

DETAILED DESCRIPTION OF THE INVENTION

[00013] An LED if overheated, the performance is deteriorated. Hence, to avoid such heating up of the light emitting diode the present invention, describes a better heat dissipation for a light emitting diode by providing a means for more efficient heat dissipating mechanism. The present invention is hereinafter described with reference to the drawings. As illustrated in Fig. 1, the light emitting diode device as per the present invention comprises a semiconductor die 102 and is characterized by an elongated thermal slug 100, which protrudes from a mounting platform 101 on which the light emitting diode device is mounted. This semiconductor die 102 is the semiconductor wafer or chip responsible for the emission of light. The thermal slug used herein, on which the semiconductor die is placed, is a good conductor of heat. This semiconductor die is placed on the thermal slug in such a way that the thermal slug is capable of conducting the heat generated by the semiconductor wafer in a direction away from the semi conductor wafer. In the current invention, as shown in Figure 1, 101 is the mounting platform, which can be a printed circuit board on which the LED is mounted.

Apart from the mounting platform 101, the die 102, the material slug 100a, the LED plastic cover 104, and LED leads 105 form the parts of an LED and all these parts taken together is called as an LED. The mounting platform 101 is a printed circuit board. The plastic cover 104 helps to secure and protect the semi conductor die from the vibrations and other outer forces, which can destroy the electrical connection between the die and the leads and can alter the positioning and direction of the leads and the die. In the current invention, the thermal slug 100 passes through a cut out 103 in the mounting platform 101. One end 100a of the thermal slug 100 is connected to the LED 102 and the other end 100b protrudes from the mounting platform 101. The elongated thermal slug 100 directly dissipates heat generated by the LED 102 to the outside of the mounting platform 101. The heat can either be dissipated to the outside air or to a heat sink secured to the end 100b of the thermal slug 100. In the present invention, the mounting platform is preferably a Printed Circuit Board (PCB). The thermal slug 100 is made of material having very high thermal conductivity such as copper or silver.

[00014] The current invention, mainly deals with the design of efficient thermal slug as shown in Figure 2. Figure 2 illustrates another embodiment of the present invention. As shown in Fig. 2, pluralities of fins are formed in the thermal slug end 100b which protrudes from the mounting platform 101. The fins in the thermal slug increase the area of the thermal slug by a considerable amount. Since, the heat dissipation through a body is directly proportional to the area of the body; more the area of the body, more will be the heat dissipation through that body. Using above principle, the area of the thermal slug is increased by making fins in the thermal slug. The fin arrangement increases the rate of heat transfer and hence heat dissipation and heat dissipation rate by the thermal slug 100 is made more efficient. In addition, these fins in the thermal slug can be connected to any larger heat sink to drain out most of the heat out of the LED die and wafer to the outer heat sink thus cooling the LED die and the semiconductor wafer by a considerable amount. Also, the fins of the thermal slug are designed in such a way so that the fins of the thermal slug can mate efficiently with the body part of the outer larger heat sink.

[00015] Fig. 3 illustrates yet another embodiment of the present invention. The end 100b of the thermal slug 100 that protrudes from the mounting platform 101 is threaded in this embodiment. The threading on the thermal slug instead of a plain thermal slug also increases the effective area for heat dissipation. Apart from increasing the surface area of the thermal slug by using the threaded thermal slug, these threads can also be used to secure the thermal slug onto the external larger heat sink thus facilitating the heat dissipation in a more effective manner. This arrangement facilitates securing of a heat sink to the thermal slug 100. Securing of a heat sink to the thermal slug 100 would further improve dissipation of heat generated by the LED.

[00016] The arrangement as per the present invention substantially increases the useful life of an LED. The elongated thermal slug is simple in design and is cost effective. Heat dissipation has been made highly efficient and timely since the thermal slug directly dissipates heat to the outside of the mounting platform. The light emitting diode device as per the present invention can be used in any mounting platform and can be incorporated in lighting arrangements used in various applications, such as in two wheeled vehicles.

We claim:

1. A solid state light emitting device, the said light emitting device comprising of a light emitting diode; wherein the said light emitting diode is characterized by an elongated thermal slug connected at one end of the light emitting diode, the said thermal slug consists of plurality of fins, which dissipate heat generated in the light emitting diode.

2. A solid state light emitting device, the said light emitting device comprising of a light emitting diode; wherein the said light emitting diode is characterized by an elongated thermal slug connected at one end to the light emitting diode, the said thermal slug consists of threads, which dissipate heat generated in the light emitting diode.

3. The light emitting diode device as claimed in claim 1 and claim 2 wherein the thermal slug has high thermal conductivity.

4. The light emitting diode device as claimed in claim 1 and claim 2 wherein the thermal slug fins and the threads respectively are attached to a heat sink arrangement to dissipate heat generated by the light emitting diode.