US20130092362A1

US20130092362A1 - Heat dissipating structure for light bulb

Info

Publication number: US20130092362A1
Application number: US13/366,706
Authority: US
Inventors: I-Ming Chen
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-10-13
Filing date: 2012-02-06
Publication date: 2013-04-18
Also published as: JP3175599U; TWM423207U

Abstract

The present invention provides a heat dissipating structure for a light bulb and enhances the heat dissipating efficiency of the light bulb. The heat dissipating structure comprises a heat dissipating housing and a plurality of fins. The light source is assembled on the plurality of fins. The heat generated by the light source is conducted to the heat dissipating housing via the plurality of fins. In addition, a power driver is disposed at the bottom of the plurality of fins and dissipates heat through the heat dissipating housing. Thereby, the light source and the power driver, which are two heat sources, are disposed separately. Then the heat is transferred to the surrounding environment by means of the heat dissipating housing. Consequently, the overall heat dissipating process is accelerated, thus improving the light emitting efficiency and lifetime of the light bulb.

Description

FIELD OF THE INVENTION

The present invention relates generally to a heat dissipating structure for a light bulb, and particularly to a heat dissipating structure for a light bulb capable of enhancing the heat dissipating efficiency.

BACKGROUND OF THE INVENTION

Modern tungsten filament incandescent lamps are invented around at the turn of 20th century. The light-emitting member therein is a filament made of tungsten, which is characterized in high melting point and hence maintaining its solid state at high temperatures. Consequently, the light bulb can have a certain lifetime; the filament will not burn broken within a short time. In practice, the temperature of the filament in a lighted incandescent lamp is as high as 3000° C. It is the light radiation generated by the heated filament that the lamp could emit light. Thereafter, nights will no longer be barriers for people's lives. With the shiny light of incandescent lamps, various night activities, including works or living, can go on with convenience and thus creating more possibilities. Thereby, the invention of incandescent lamps alters the lifestyle of people significantly and extends the active time sections into more directions, hence enabling possibilities in varied developments.
With the progress of lighting technologies, a variety of lighting lamps are developed. Among all of electrical lighting lamps, incandescent lamps are least efficient. Only 12-18% of the consumed electrical energy is converted into light, meaning a very bad energy conversion. The rest energy is dissipated in the form of heat, which means most energy is wasted. Following the daily advancement of technologies, the light-emitting diodes (LEDs) technology as well as the associated integrated-circuit control devices and heat dissipating technology are getting mature, enabling diversified applications such as low-power power indicators, light sources for keypads of mobile phones, LED backlight modules, and general lighting products. They are gradually replacing the traditional light-emitting sources. As opposed to the short lifetime and generated heat of incandescent lamps, LEDs own the advantages of low power consumption, no mercury, no halides, and low carbon dioxide emissions. In considering the environmental protection issue including saving energy, reducing carbon emissions, and reducing mercury and halide usage, many countries have set a deadline for starting prohibition against usage of incandescent lamps. Meanwhile, LEDs will be promoted completely.
Because LEDs feature point-source lighting behavior, they are more flexible in design. They can make up lighting lamps having distributed light sources and hence not offending to the eye; they can constitute lighting lamps focusing at a point or over a specific zone; they also can generate vivid and bright colors. The light emitting efficiency of white LEDs has been over 701 m/W, exceeding 151 m/W of incandescent lamps. Currently, only 35% of the input power to LEDs is converted into light. The rest 65% is converted into heat, which is the main cause of low light emitting efficiency for LEDs. In addition, if the heat dissipating mechanism of the whole device is bad, the generated head by LEDs will accumulate therein and hence shortening the lifetime of LEDs. In general, the lifetime of a LED lamp is above 100,000 hours. Nonetheless, if the operating temperature is above 85° C., its lifetime will be greatly reduced.
Accordingly, when light bulbs, including LED bulbs, are being used, heat generation is an inevitable result. Heat dissipation is the method for solving this problem. The emphasis of related technologies will be put on how to improve the heat dissipating efficiency of each component and thus increasing the lifetime. In addition to the light source, in a light lamp, there is still a power driver, which will generate heat, too. If heat dissipation of the power driver is inferior, the efficiency of LED lamp will still be bad. Even worse, the LED lamp possibly cannot be turned on. Thereby, if both of these two parts have bad heat dissipation or even influence each other, the temperature will goes up tremendously. In addition to reducing the lifetime of the LED lamp, the room temperature might possibly be raised and leading to discomfort of users. Accordingly, the mechanism of heat dissipation is a very important subject in this field.
Almost all of the heat dissipating structures of current bulbs in the market are of outer fin type. The outer fins of the structure extend from the center of the bulk. A space is left at the center for accommodating the power driver, which itself is a heat generating member. When the heat generated by the light source is conducted to the outer fins by thermal conduction, heat will completely surround the power driver. Then, the heat will be added to heat generated by the power driver and producing the co-heating effect. Owing to this effect, the internal temperature will be exceedingly high, resulting in damages on the electronic components, such as electrolyte capacitors, which have maximum operating temperature of 105° C. and lifetime of 8,000 hours, in the power driver. In addition to severely affecting the lifetime of the power driver, the light emitting efficiency is lowered because the temperature of the light source cannot be reduced due to the co-heating effect. Instead of the light emitting efficiency of the light source itself, the lowering in light emitting efficiency is frequently caused by damages in the power driver.
According to the outer-fin typed heat dissipating structure, only heat generated by the light source can be dissipated by an imperfect heat dissipating mechanism. For the power driver placed therein, no mechanism exists for dissipating the heat generated thereby. Besides, the heat generated by the power driver and by the light source will induce the co-heating effect, which will result in damages of the electronic components in the power driver and thus affecting the lifetime of the light bulb. The present invention provides a heat dissipating structure for a light bulb, which is mainly used in heat dissipation of the light bulb. The heat dissipating structure according to the present invention improves the drawbacks of the outer-fin typed heat dissipating structure as well as providing a heat dissipating method for the power driver in order to solve the co-heating effect effectively. Thereby, in addition to enhancing the lifetime of the light bulb, thanks to the improvement in heat dissipation, the light emitting efficiency of the light source can be raised as well. For users, it is safer. The subsequent problems caused by damages of the light bulb because of high temperature can be eliminated.

SUMMARY

An objective of the present invention is to provide a heat dissipating structure for a light bulb, which uses a heat dissipating housing. A plurality of fins are disposed inside and surrounding the heat dissipating housing, so that the contact area between the heat dissipating housing and air can be increased. Thereby, heat energy can be transferred to the surrounding environment rapidly. The heat dissipating process is accelerated. The overall heat dissipating mechanism and performance are enhanced. Accordingly, the lifetime of the light bulb is improved.
Another objective of the present invention is to provide a heat dissipating structure for a light bulb, which uses a power connecting part. A power driver is disposed in the power connecting part. The power connecting part is disposed at the bottom of the plurality of fins. The heat dissipating housing and the power connecting part are separated effectively and maintaining a spacing. Thereby, the heat generated by the power driver in the power connecting part can be dissipated through heat dissipating holes on the heat dissipating housing.
For achieving the objectives described above, the present invention provides a heat dissipating structure for a light bulb comprising a heat dissipating housing and a plurality of fins. The plurality of fins are disposed surrounding the inner walls of the heat dissipating housing. The light source is disposed on the plurality of fins. When the light source generates heat, the heat is conducted to the heat dissipating housing via the fins contacting directly with the light source and dissipated through the heat dissipating housing. By means of the structure, the heat dissipating process can be accelerated. Heat will not be accumulated in the light source. Thereby, the light emitting efficiency and lifetime of the light source can be improved substantially.
In addition, the present invention further comprises a power connecting part. A power driver is disposed in the power connecting part. The power connecting part is disposed at the bottom of the plurality of fins for separating the light source and from the power connecting part. The heat dissipating housing can dissipate effectively the heat generated by the power driver. Thereby, the lifetime of the power driver, and hence that of the light bulb, are improved.
Moreover, the heat dissipating housing of the heat dissipating structure further comprises a plurality of heat dissipating holes disposed on the surfaces of the heat dissipating housing and the power connecting part. Thereby, the heat dissipating efficiency can be raised.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a top view of the heat dissipating structure according to a preferred embodiment of the present invention;

FIG. 1B shows a side view of the heat dissipating structure according to a preferred embodiment of the present invention;

FIG. 1C shows a bottom view of the heat dissipating structure according to a preferred embodiment of the present invention;

FIG. 1D shows a three-dimensional view of the heat dissipating structure according to a preferred embodiment of the present invention;

FIG. 2A shows a top view of the heat dissipating structure according to another preferred embodiment of the present invention;

FIG. 2B shows a side view of the heat dissipating structure according to another preferred embodiment of the present invention;

FIG. 2C shows a bottom view of the heat dissipating structure according to another preferred embodiment of the present invention;

FIG. 2D shows a three-dimensional view of the heat dissipating structure according to another preferred embodiment of the present invention;

FIG. 3 shows a schematic diagram of the assembly of the light source and the heat dissipating structure according to another preferred embodiment of the present invention;

FIG. 4 shows a schematic diagram of the light source and the heat dissipating structure after assembly according to another preferred embodiment of the present invention; and

FIG. 5 shows a three-dimensional view of the heat dissipating structure adopting a solid member according to another preferred embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the structure and characteristics as well as the effectiveness of the present invention to be further understood and recognized, the detailed description of the present invention is provided as follows along with embodiments and accompanying figures.
The present invention relates to a heat dissipating structure for a light bulb, which is provided for solving the problems encountered by the outer-fin type dissipating structure. The drawbacks include difficult heat dissipation of the light source and the co-heating effect of the light source and the power driver. According to the heat dissipating structure of the present invention, the light emitting efficiency and lifetime of light bulbs can be improved.
FIGS. 1A, 1B, 1C, and 1D show top, side, bottom, and three-dimensional views of the heat dissipating structure according to a preferred embodiment of the present invention. A heat dissipating structure 10 according to the present invention comprises a heat dissipating housing 11 and a plurality of fins 12. The plurality of fins 12 surrounds the inner walls of the heat dissipating housing 11. The heat generated by the light source is transferred to the heat dissipating housing 11 via the plurality of fins and hence dissipating the heat. The lengths of the plurality of fins 12 can be different or identical. According to prior art, heat is dissipated via a cup-shaped member. The function and structure of the cup-shaped member is similar to the heat dissipating housing according to the present invention. A great deal of the generated heat is absorbed first by the thin cup-shaped member and then dissipated via fins. Because the absorption enthalpy of the thin cup-shaped member is quite limited, the overall heat cannot be dissipated efficiently by first absorbed by the cup-shaped member and then transferred to the fins for heat dissipation. On the contrary, according to the present invention, heat is first absorbed by the plurality of fins 12 and then dissipated by means of the heat dissipating housing 11. Because the total absorption enthalpy of the plurality of fins 12 is greater than that of the heat dissipating housing 11, the present invention has better heat dissipating efficiency.
Besides, the heat dissipating housing 11 of the heat dissipating structure further comprises a plurality of first heat dissipating holes 111 disposed on the surface of the heat dissipating housing 11. After the plurality of fins 12 absorb heat, the heat is transferred to the heat dissipating housing 11 for dissipation. In addition, the plurality of heat dissipating holes 11 are used for heat convection. Air enters to the end having lower temperature and heat is exhausted from the end having higher temperature. Thereby, the heat absorbed by the plurality of fins 12 is exhausted efficiently. According to the present invention, heat exchanged is performed between the surfaces of the plurality of fins 12 and of the heat dissipating housing 11 and external air. Moreover, the plurality of first heat dissipating holes 11 can reinforce heat convection and thus enhancing cooling effect. The diameters of the plurality of first heat dissipating holes 111 increase progressively from the bottom having a narrower opening to the top having a wider opening. The arrangement of the diameters of the plurality of first heat dissipating holes 111 is not limited the progressive increase fashion as described above. Other variations in diameters are possible and can be adjusted flexibly according to the practical requirements. Thereby, the heat dissipating efficiency is further improved.
In addition, the present invention further comprises an accommodating part 13 disposed at the bottom of the plurality of fins 12 and inside the heat dissipating housing 11. The function of the accommodating part 13 will be described later.
FIGS. 2A, 2B, 2C, and 2D show top, side, bottom, and three-dimensional views of the heat dissipating structure according to another preferred embodiment of the present invention. The fins of a heat dissipating structure 20 according to the present invention have a different shape as shown in the figures. The heat dissipating structure 20 comprises a heat dissipating housing 21 and a plurality of fins 22. The plurality of fins 22 surrounds the inner walls of the heat dissipating housing 21. The plurality of fins 22 further comprises an annular member 222, which is hollow. Some of the plurality of fins 22 extends to the central part of the annular member 222. The plurality of fins 22 and the annular member 222 can be an integral structure. Thereby, the heat generated by the light source is transferred efficiently to the heat dissipating housing 21.
Moreover, the present invention further comprises an accommodating part 23 disposed at the bottom of the plurality of fins 22 and inside the heat dissipating housing 21. The function of the accommodating part 23 will be described later.
FIG. 3 shows a schematic diagram of the assembly of the light source and the heat dissipating structure according to another preferred embodiment of the present invention; FIG. 4 shows a schematic diagram of the light source and the heat dissipating structure after assembly according to another preferred embodiment of the present invention. The light bulb according to the present invention comprises a light source 30, which includes a substrate 32. The substrate 32 contacts the top of the plurality of fins 12; the sides of the substrate 32 touches closely the upper end of the inner walls of the heat dissipating housing 11, wherein thermally conductive paste can be used for tightly adhering both to each other. The present invention further comprises a power connecting part 34 disposed in the accommodating part 13. The power connecting part 34 is hollow and has a power driver 342 disposed therein. When the power driver 342 is disposed inside the power connecting part 34, thermally conductive paste can be applied too for transferring the heat generated by the power driver 342 to the power connecting part 34 rapidly. A plurality of LED chips are disposed on the substrate 32. For a better heat dissipating effect, thermally conductive paste or heat sinks can be used on the contact surface between the substrate 32 and the plurality of fins 12 for touching each other closely. Be means of heat conduction, heat can be transferred rapidly from the substrate 32 to the plurality of fins 12 and to the heat dissipating housing 11.
The light source 30 further includes a lampshade 31 disposed above the substrate 32. The material of the lampshade 31 includes transparent or light dispersive materials. The light source 30 adopts LED modules and LEDs are point light sources. For avoiding visual discomfort caused by the glare, the lampshade 31 adopts the acrylic materials having light dispersion particles for dispersing the light of LEDs.
Furthermore, the heat dissipating housing 11 of the heat dissipating structure 10 has the plurality of first heat dissipating holes 111. Because the plurality of first heat dissipating holes 111 are dispose on the surface of the heat dissipating housing 11, the heat dissipating efficiency of the heat dissipating housing is improved. The plurality of fins 12 of the heat dissipating structure 10 further include a plurality of screw holes 121. A plurality of screws 321 are screwed into the plurality of screw holes 121 on the plurality of fins 12 for fixing the substrate 32. The material of the plurality of screws 321 can be material having high thermal conductivity, for example, copper, gold, aluminum, and other metals or ceramic materials having good heat dissipating capability.
Because the substrate 32 is the heat source, its heat dissipating mechanism varies according to various parts thereof First, at the bottom of the substrate 32, the generated heat is guided to the heat dissipating housing 11 via the plurality of fins 12 for heat dissipation. Next, the heat generated at the sides of the substrate 32 can be transferred outwards thanks to their direct contact with the heat dissipating housing 11 and then convected with external air and thus achieving heat dissipation. Finally, heat dissipation at the top of the substrate is accomplished by guiding the heat directly to the plurality of fins 12 by means of the plurality of screws 321 and then transferring the heat to the bottom of the heat dissipating housing for rapid heat dissipation. Thereby, the heat dissipating mechanism according to the present invention features multiple heat guiding channels for bringing the heat of the substrate 32 away rapidly.
In addition, the power connecting part 34 in the light source 30 further includes a plurality of second heat dissipating holes 341. A lid 33, which isolates the heat generated by the substrate 32 from the power connecting part 34, is disposed above the power connecting part 34. Without such isolation, the electronic components of the power driver 342 inside the power connecting part 34 will be damaged owing to the co-heating effect caused by the heat transferred from the substrate 33. Besides, there is no heat dissipating method for the power driver 342 in prior art. Hence, the heat of the power driver 342 in the light bulb cannot be dissipated. If the substrate 32 is not isolated from the power driver 342, the heat of the substrate 32 and that of the power driver 342 induce the co-heating effect. The generated high temperature affects the lifetime and light emitting efficiency of the light bulb. The lifetime of the LED chips as well as that of the power driver are also affected. Thereby, the plurality of second heat dissipating holes 341 and a plurality of vertical heat dissipating holes 343 are disposed on the side and vertical surfaces of the power connecting part 34. The disposal of the plurality of heat dissipating holes 341, 343 matches the first heat dissipating holes 111 on the heat dissipating housing 11, avoiding them from being blocked by the plurality of fins 12. Consequently, the convecting air can flow outwards directly, and thus improving the heat dissipating efficiency of the power driver 342. According to the present embodiment, when the light bulb is used horizontally, cold air enters from the bottom via the plurality of second heat dissipating holes 341 and hot air exhausts to the top by convection for expelling the heat generated by the power driver 342. On the other hand, when the light bulb is used vertically, air is exchanged through the plurality of vertical heat dissipating holes 343. Thereby, no matter what direction the light bulb is used, the heat generated by the power driver 342 can be exhausted by thermal convection. Accordingly, when the heat dissipating structure according to the present invention is applied to a light bulb, its application will not be limited to a single direction, and hence bringing more convenience in usage.
FIG. 5 shows a three-dimensional view of the heat dissipating structure adopting a solid member according to another preferred embodiment of the present invention. As shown in the figure, the center of the annular member 222, which is disposed in the heat dissipating structure 20 and connecting with the plurality of fins 22, can be solid member 223. Alternatively, a plurality of the annular members 222 connecting with the plurality of fins 22 can be adopted. The number can be adjusted according to the requirement. The shape or number is not limited to the above description.
To sum up, the present invention provides a heat dissipating structure for a light bulb and enhances the heat dissipating efficiency of the light bulb. The heat dissipating structure comprises a heat dissipating housing and a plurality of fins. The light source is assembled on the plurality of fins. The heat generated by the light source is conducted to the heat dissipating housing via the plurality of fins. In addition, a power driver is disposed at the bottom of the plurality of fins and dissipates heat through the heat dissipating housing. Thereby, the light source and the power driver, which are two heat sources, are disposed separately. Then the heat is transferred to the surrounding environment by means of the heat dissipating housing. Consequently, the overall heat dissipating process is accelerated, thus improving the light emitting efficiency and lifetime of the light bulb and advantaging industrial and domestic applications.
Accordingly, the present invention conforms to the legal requirements owing to its novelty, nonobviousness, and utility. However, the foregoing description is only embodiments of the present invention, not used to limit the scope and range of the present invention. Those equivalent changes or modifications made according to the shape, structure, feature, or spirit described in the claims of the present invention are included in the appended claims of the present invention.

Claims

1. A heat dissipating structure for a light bulb, comprising:

a heat dissipating housing; and

a plurality of fins, disposed surrounding the inner walls of said heat dissipating housing.

2. The heat dissipating structure for a light bulb of claim 1, and further comprising a substrate, screwed on said plurality of fins.

3. The heat dissipating structure for a light bulb of claim 1, wherein said plurality of fins further comprise a annular member disposed at the center of said heat dissipating housing and connecting with said plurality of fins.

4. The heat dissipating structure for a light bulb of claim 3, wherein said annular member is hollow.

5. The heat dissipating structure for a light bulb of claim 3, wherein said annular member connects with said plurality of fins and some of said plurality of fins extend to the central part of said annular member.

6. The heat dissipating structure for a light bulb of claim 3, wherein the center of said annular member is a solid member.

7. The heat dissipating structure for a light bulb of claim 1, wherein a plurality of first heat dissipating holes are disposed on said heat dissipating housing.

8. The heat dissipating structure for a light bulb of claim 7, wherein the diameters of said plurality of first heat dissipating holes increase progressively from the bottom of said heat dissipating housing.

9. The heat dissipating structure for a light bulb of claim 1, wherein a plurality of screw holes are disposed on said plurality of fins.

10. The heat dissipating structure for a light bulb of claim 1, wherein not all of the lengths of said plurality of fins are identical.

11. The heat dissipating structure for a light bulb of claim 1, wherein said heat dissipating housing and said plurality of fins are formed integrally.

12. The heat dissipating structure for a light bulb of claim 1, wherein an accommodating part is disposed at the bottom of said plurality of fins.

13. The heat dissipating structure for a light bulb of claim 12, wherein a power connecting part is disposed in said accommodating part and said power connecting part is a hollow member.

14. The heat dissipating structure for a light bulb of claim 13, wherein a power driver is disposed in said power connecting part.

15. The heat dissipating structure for a light bulb of claim 13, wherein a plurality of second heat dissipating holes are disposed on said power connecting part.

16. The heat dissipating structure for a light bulb of claim 15, wherein a plurality of first heat dissipating holes are disposed on said heat dissipating housing and opposed to said plurality of second heat dissipating holes.

17. The heat dissipating structure for a light bulb of claim 13, wherein a plurality of vertical heat dissipating holes are disposed at the bottom and top of said hollow member.

18. The heat dissipating structure for a light bulb of claim 17, wherein a plurality of second heat dissipating holes are disposed on said power connecting part, and said plurality of vertical heat dissipating holes are disposed opposed to said plurality of second heat dissipating holes.