TWI409407B - Strengthen the heat of the LED lights - Google Patents

Abstract

A LED lamp with enhanced heat dissipation includes a LED lampwick, a heat-conductive insulation material filled in the chamber of lamphead, an electrode mechanically contacting with the lampwick, and the lamphead for conducting heat from the lampwick to the electrode, and a lamp cover adhered on the lamphead for conducting the heat from the electrode to the lamp cover. As a result, the lamp cover provides an enlarged area of heat dissipation and the assistance to the lampwick in heat dissipation.

Description

Enhanced heat-dissipating LED light

The present invention relates to an electric lamp, and more particularly to a light emitting diode (LED) lamp that can directly replace a conventional tungsten wire, a halogen or a power saving bulb.

An LED lamp using a direct current LED device as a wick must use a power converter to convert alternating current into direct current to supply the direct current LED device, thereby increasing the cost of the LED lamp. In addition, it is difficult for the power converter to be completely hidden in the standard lamp holder of the conventional bulb. Therefore, it is necessary to separately develop a mold member that is different from the conventional bulb, which not only increases the cost but also increases the volume of the LED lamp. The DC LED device generates heat when it is energized, so an additional heat dissipation mechanism must be designed to handle this heat. If the heat is not effectively dissipated, the high temperature may cause adverse effects such as reduced luminous efficiency of the LED, reduced lifetime, and wavelength shift. In the process of converting AC power into DC power, the power converter also generates heat energy, especially the inductor and integrated circuit. The high temperature also damages such components, causing the product to be inoperable. Especially in high-power applications, such as lighting fixtures, DC LED devices generate higher thermal energy, so the situation caused by insufficient heat dissipation is more serious. Some products use multiple low-power, bullet-type LEDs and use simple bridge rectifiers to accommodate small, traditional lamp heads. However, the low-power LED brightness is generally too low, the market acceptance is limited, and such products often have poor light dissipation due to poor heat dissipation.

In recent years, the technology of LED devices using alternating current has become increasingly mature, and the brightness has also been increasing, which has commercial value. The alternating current LED device is formed by serially and parallelly connecting a plurality of LEDs on the same epitaxial wafer. After the epitaxial wafer is packaged, a resistor having a certain resistance value is connected in series, and can directly withstand a high voltage such as 110 volts or 220 volts. Therefore, the power converter or rectifier circuit required for the DC LED device is omitted, which effectively reduces the cost and reduces the quality problems caused by the circuit. Although the AC LED device is convenient for use in a small volume of space, there is still a problem of heat dissipation that must be addressed. Especially in high-power applications, such as lighting fixtures, the heat energy generated is higher. If a radiator is added, the volume and cost of the LED lamp will increase. If the AC LED device is not helped to dissipate heat, it will cause LED. Reduced luminous efficiency, reduced lifetime and wavelength shift, and even burned LED epitaxial wafers.

The applicant of the present invention has proposed an LED lamp in the patent application No. 098115441, which is filled with a heat conductive insulating material in the lamp cap, thereby transferring thermal energy from the LED wick to the lamp cap, so that the electrode of the lamp cap helps the LED wick to dissipate heat. This application is a further improvement of this prior case.

One of the objects of the present invention is to provide an LED lamp that enhances heat dissipation of an LED wick.

One of the objects of the present invention is to provide an LED lamp with improved light extraction rate. According to the present invention, a heat-dissipating LED lamp includes a wick including at least one alternating current LED device, a lamp cap having a chamber in which a thermally conductive insulating material is filled, mechanically contacting the wick and an electrode of the lamp cap to assist Thermal energy is conducted from the wick to the electrode and a lamp cover is adhered to the lamp cap to help conduct thermal energy from the electrode to the lamp cover. The lampshade is used to expand the heat dissipation area to further improve the heat dissipation effect.

Preferably, the thermally conductive insulating material is partially interposed between the wick and the lamp cover to help conduct thermal energy from the wick to the lamp cover. Preferably, the thermally conductive insulating material of this portion has a white surface to increase the light extraction rate.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a first embodiment of the present invention. To highlight the features of the present invention, this embodiment uses a standard base 10 for small bulbs having electrodes 12 and 14 for connection to an AC power source. As is well known to those of ordinary skill in the art, the electrode 12 is a metal shell having a spiral profile 16 having a chamber 18 therein. This embodiment uses an AC LED device 20 as the wick that secures the AC LED epitaxial wafer 22 to the bracket 24 and overlies the encapsulant 26. The LED package is a conventional technique, and the detailed package structure of the AC LED device 20 is not depicted here for the sake of simplicity. One end of the resistor 30 is soldered to the electrode 14, and the other end is soldered to the LED device 20 by a wire 32, and both ends of the wire 34 are soldered to the electrode 12 and the alternating current LED device 20, respectively. The equivalent circuit of this LED lamp is shown in FIG. 2, and an alternating current LED epitaxial wafer 22 and a resistor 30 are connected in series between the electrodes 12 and 14. As is well known to those of ordinary skill in the art, an so-called alternating current LED epitaxial wafer having two oppositely arranged LEDs connected in parallel between two legs, each having at least one LED in the direction, the two The LEDs in the opposite direction are illuminated in the positive and negative half cycles of the AC power supply. The magnitude of the resistance value R of the resistor 30 is selected according to the current value required by the design. The resistor 30 also has the function of protecting the alternating current LED epitaxial wafer 22, which absorbs most of the surge voltage when a surge occurs in the alternating current source connected to the electrodes 12 and 14. Returning to Figure 1, one of the features of the present invention is to fill the chamber 18 with a thermally conductive insulating material 36 having a first portion underneath the wick that mechanically contacts the bracket 24 and the electrode 12 to provide a first thermal path to the alternating current LED. The epitaxial wafer 22 is conducted to the electrode 12 for heat dissipation due to heat energy generated by energization. As is well known to those of ordinary skill in the art, the bracket 24 typically contains a metal sheet that assists in dissipating heat from the AC LED epitaxial wafer 22. Thus, the bracket 24 is attached to the thermally conductive insulating material 36 for good thermal conductivity. In addition to helping the AC LED epitaxial wafer 22 to dissipate heat, the thermally conductive insulating material 36 also helps the resistor 30 to dissipate heat because the resistor 30 is buried in the thermally conductive insulating material 36. As shown in a partially enlarged view to the right side of FIG. 1, the second portion 78 of the thermally conductive insulating material 36 adheres the globe 40 to the base 10, thereby providing a second thermal path for conducting thermal energy from the base 10 to the globe 40, the thermally conductive insulating material 36. The third portion 80 is interposed between the wick and the shade 40, thereby providing a third thermal passage that conducts thermal energy from the wick to the shade 40. Because the light cover 40 expands the heat dissipation area, it can provide better heat dissipation. Preferably, the third portion 80 of the thermally conductive insulating material 36 has a white surface 82 to reduce absorption of light and increase reflection of light, thereby increasing the light output of the LED lamp.

The thermally conductive insulating material 36 may be selected from epoxy resins, or thermally conductive powders such as alumina, aluminum nitride, boron nitride or other thermally conductive materials, or a mixture of the two. To form a white surface 82, a white pigment may be applied to the third portion 80 of the thermally conductive insulating material 36 or the titanium dioxide may be incorporated into the thermally conductive insulating material 36.

Conventional bulbs use standard bases. For example, E12, E14, E17, E26 and E27 are the bases of conventional tungsten bulbs, and MR16 and GU10 are the bases of conventional halogen bulbs.

As shown in FIG. 1, the LED lamp has the same size as the lamp cap 10, and has good heat dissipation capability, and can achieve high power applications that cannot be achieved by conventional techniques. In the lamp head of a conventional halogen bulb, one electrode is a columnar metal shell separated by an insulator from the other electrode. Some standard lamp caps use two needle electrodes that are insulated from each other. Whether it is a conventional tungsten bulb, a conventional halogen bulb or other standard lamp caps, the chamber can be filled with a thermally conductive insulating material, so at least one electrode can be used to help dissipate the wick of the LED lamp. Because the electrode of the lamp cap is exposed to the outside, it can provide a good heat dissipation effect.

The AC LED epitaxial wafer 22 containing a larger number of LEDs can be used to increase the brightness of the LED lamp. 3 is a schematic diagram of several alternating current LED epitaxial wafers 22, the first is to connect two strings of opposite LEDs in parallel between two pins, each string comprising more than two LEDs; the second type is in two branches Two pairs of LED pairs are connected in series between the legs, and each pair of LED pairs are connected in parallel with two LEDs in opposite directions; the third system is configured with a bridge structure of five or more LEDs. These are already commercially available products.

The lamp cover 40 serves as a protective cover to prevent moisture, dust or external force from being applied to the internal components of the LED lamp. The lampshade 40 also functions as an optical component to produce various desired optical effects through atomization, geometric design, and the like. The mist structure of the globe 40 can be produced by sand blasting, etching, electrostatic powder coating, coating of silicone, painting or injection molding.

Figure 4 is a schematic illustration of a second embodiment of the present invention. The wick of this embodiment includes a circuit board 28 and an alternating current LED device 20 thereon, and the alternating current LED device 20 includes at least one alternating current LED epitaxial wafer 22. The series resistor 38 is instead mounted on the circuit board 28 and the circuit board 28 is connected between the electrodes 12 and 14 by wires 34 and 32. The circuit board 28 may be a reinforced fiberglass (FR4) or metal substrate (IMS) component; the AC LED device 20 and the series resistor 38 may be surface mounted components (SMD) mounted on the circuit board using surface mount technology (SMT). 28 on. Because the resistor 38 is soldered to the circuit board 28, a variable resistor can be used to increase the flexibility of the application, such as to facilitate adjustment of the current through the AC LED device 20. The amount of thermally conductive insulating material 36 is filled to cover it onto circuit board 28, such that third portion 80 of thermally conductive insulating material 36 is above circuit board 28, as shown in a partially enlarged view to the right. Other features are the same as in the embodiment of FIG. If you want to increase the brightness of the LED lights, you can use more AC LED devices 20 in series, parallel or series and parallel. For example, the multi-elongation wafer wick shown in FIG. 5 is connected in parallel with three rows of alternating current LED devices 20 between the pads 52 and 54 of the circuit board 28, each row containing three alternating current LED devices 20. If the power of each of the AC LED devices 20 is 1 watt, the wick can reach 9 watts.

The wick of FIG. 1, FIG. 4 and FIG. 5 attaches the AC LED device 20 to the circuit board 28. Alternatively, the AC panel 104 can be packaged on the circuit board 28, which directly attaches the bare crystal of the AC epitaxial wafer 22. On the circuit board 28, the sealant 26 is covered after the wire is applied.

6 is a schematic view of a third embodiment of the present invention. The alternating current LED device 20 is soldered to the surface of the heat conducting member 50, and the other end of the heat conducting member 50 is embedded in the thermally conductive insulating material 36, and is buried in the thermally conductive insulating material 36. The height of the alternating current LED device 20 is adjusted in depth. Other features are the same as in the embodiment of FIG.

7 is a schematic view of a fourth embodiment of the present invention, using a circuit board 28 having a perforation 60, one end of which is above the circuit board 28, and the other end is buried in the thermally conductive insulating material 36 through the through hole 60, the alternating current LED device 20 is welded to the exposed end of the heat conducting member 50. The pin 66 of the AC LED device 20 is soldered to the circuit board 28, and solder 70 is soldered to the electrode 12 in the through hole 64 of the circuit board 28. Resistor 30 is soldered between electrode 14 and circuit board 28 such that resistor 30 is in series with alternating current LED device 20 between electrodes 12 and 14. The circuit board 28 can be selected from reinforced glass fibers or metal substrates. Preferably, circuit board 28 also mechanically contacts thermally conductive insulating material 36. In various embodiments, resistor 30 can also be replaced with a resistor soldered to circuit board 28, or a resistor can be added to circuit board 28 in series with resistor 30. Preferably, the upper surface of the circuit board 28 is coated with a white pigment to increase the light extraction rate of the LED lamp. Other features are the same as the embodiment of FIG.

Figure 8 is a schematic illustration of a fifth embodiment of the present invention using a circuit board 28 having perforations 60 on which an alternating current LED device 20 is soldered, a first portion of thermally conductive insulating material 36 mechanically contacting the bottom of the alternating current LED device 20 via a perforation 60. The third portion 80 of the thermally conductive insulating material 36 overlies the circuit board 28. Preferably, it covers the surface of the circuit board 28 as much as possible, except for the alternating current LED device 20. The third portion 80 of the thermally conductive insulating material 36 has a white surface to increase the light extraction rate. Other features are the same as in the embodiment of FIG.

The LED lamp of Fig. 8 is replaced with a half cover type lampshade 40. As shown in Fig. 9, the inner surface of the lamp cover 40 can be coated or coated with a reflective material to form a reflective surface 86. Other features are the same as the embodiment of FIG.

The embodiment of Figure 10 uses a circuit board 28 having a metal substrate. The circuit board 28 has an aluminum layer, a copper layer and a heat conductive layer interposed therebetween, and has a heat dissipation capability higher than that of the reinforced glass fiber substrate. The AC LED device 20 is soldered to the circuit board 28 in a COB package structure. The solder 70 solders the circuit board 28 to the electrode 12, and the resistor 30 is soldered between the electrode 14 and the circuit board 28. Thus, the resistor 30 is connected in series with the AC LED device 20. Between the electrodes 12 and 14. In various embodiments, resistor 30 can also be replaced with a resistor soldered to circuit board 28, or a resistor can be added to circuit board 28 in series with resistor 30. Circuit board 28 has perforations 84 for filling thermally conductive insulating material 36 into chamber 18. Other features are the same as the embodiment of FIG.

As shown in FIG. 11, in addition to the resistor 30, a resistor 38 mounted on the circuit board 28 may be added in series between the resistor 30 and the AC LED device 20. Resistor 38 can employ a variable resistor to adjust its resistance as needed. Other features are the same as the embodiment of FIG.

12 is a structure in which an alternating current LED epitaxial wafer 22 and a wafer resistor 90 are packaged in the same package, an alternating current LED epitaxial wafer 22 and two wafer resistors 90 are attached to the spacer 88, and a bonding wire 92 is connected to the alternating current LED epitaxial wafer 22 And the chip resistor 90, the bonding wire 94 is connected to the pin 66 and the chip resistor 90, and the sealing 26 covers all the circuit structures, and the equivalent circuit thereof is as shown in FIG. The embodiment of Figure 14 is a circuit in which the components of Figure 12 are soldered between electrodes 12 and 14, the other features being the same as in the embodiment of Figure 1.

In the above embodiments, in general, the heat dissipation mechanism established by the second portion 78 and the third portion 80 of the thermally conductive insulating material 36 can help the operating temperature of the alternating current LED device 20 to be further reduced by 1 to 5 °C.

Depending on the application, the AC LED device 20 is employed with a power between 0.3 and 5 W, preferably between 1 and 3 W, and a resistor 30 or 38 of 50 to 50,000 ohms is selected. The AC LED device 20 is used between 12 and 240 volts. If a single AC LED device 20 is used, the voltage used is 110 volts or 220 volts depending on the AC power source; if multiple AC LED devices 20 are connected in series , the voltage used can be the lower one, such as 12 volts.

In addition to the various package configurations shown in the various embodiments above, other different types or packages of components may be suitable for use with the present invention.

10. . . Lamp head

12. . . electrode

14. . . electrode

16. . . Spiral shape

18. . . Chamber

20. . . AC LED device

twenty two. . . AC LED epitaxial wafer

twenty four. . . support

26. . . Plastic closures

28. . . Circuit board

30. . . Resistor

32. . . wire

34. . . wire

36. . . Thermal insulation material

38. . . Resistor

40. . . lampshade

50. . . Heat conductive member

60. . . perforation

64. . . Through hole

66. . . Pin

70. . . Solder

78. . . The second part of the thermal insulation material

80. . . The third part of the thermal insulation material

82. . . White surface

84. . . perforation

86. . . Reflective surface

98. . . Gasket

90. . . Chip resistor

92. . . Bonding wire

94. . . Bonding wire

Figure 1 is a schematic view of a first embodiment of the present invention;

2 is a schematic diagram of an equivalent circuit of the LED lamp of FIG. 1;

Figure 3 is a schematic diagram of several alternating current LED epitaxial wafers;

Figure 4 is a schematic view of a second embodiment of the present invention;

Figure 5 is a schematic view of a multi-leaf wafer wick;

Figure 6 is a schematic view of a third embodiment of the present invention;

Figure 7 is a schematic view of a fourth embodiment of the present invention;

Figure 8 is a schematic view showing a fifth embodiment of the present invention;

Figure 9 is a schematic view of a sixth embodiment of the present invention;

Figure 10 is a schematic view showing a seventh embodiment of the present invention;

Figure 11 is a schematic view showing an eighth embodiment of the present invention;

Figure 12 is a structure in which an alternating current LED epitaxial wafer and a wafer resistor are packaged in the same package;

Figure 13 is a schematic illustration of an equivalent circuit of the components of Figure 12;

Figure 14 is a schematic illustration of an embodiment using the elements of Figure 12.

10. . . Lamp head

12. . . electrode

14. . . electrode

16. . . Spiral shape

18. . . Chamber

20. . . AC LED device

twenty two. . . AC LED epitaxial wafer

twenty four. . . support

26. . . Plastic closures

30. . . Resistor

32. . . wire

34. . . wire

36. . . Thermal insulation material

40. . . lampshade

78. . . The second part of the thermal insulation material

80. . . The third part of the thermal insulation material

82. . . White surface

Claims (6)

An LED lamp for enhancing heat dissipation comprises: at least one LED wick; a lamp cap having first and second electrodes, wherein the lamp cap defines a chamber; and a resistor connected in series with the wick between the first and second electrodes a thermally conductive insulating material filled in the chamber of the lamp cap; a heat conducting member having one end mechanically contacting the LED wick and the other end embedded in the thermally conductive insulating material; and a lamp cover mounted on the lamp cap for mounting Encapsulating the LED wick; wherein the thermally conductive insulating material has a first portion mechanically contacting the heat conducting member and the first electrode, thereby providing a first heat channel to help the wick to dissipate heat to the wick via the heat conducting member and the thermally conductive insulating material An electrode, and a second portion, adheres the lamp cap to the lamp cap, thereby providing a second heat path to conduct thermal energy from the first electrode to the lamp cover. The LED lamp of claim 1, wherein the wick comprises a circuit board carrying the at least one alternating current LED device and mechanically contacting the heat conducting member. The LED lamp of claim 2, wherein a portion of the upper surface of the circuit board is coated with a white pigment. The LED lamp of claim 1, wherein the thermally conductive insulating material comprises an epoxy resin, or a thermally conductive powder, or a mixture thereof. The LED lamp of claim 1, wherein the thermally conductive insulating material has a white color s surface. The LED lamp of claim 1, wherein the thermally conductive insulating material comprises titanium dioxide.