# Patent

## Title
Electronic device

## Abstract

An electronic device includes a housing, a heat source located in a casing, and a heat dissipation device disposed in a casing. The heat dissipation device is kept apart from the heat source. The heat dissipation device includes a casing having a heat dissipation material including 15 to 30 percent volume of multiple copper materials, 50 to 85 percent volume of a phase change material, and 15 to 20 percent volume of air. The casing has a surface facing the heat source. A central area and an outer ring area are defined on the surface. A geometric midpoint of the central area overlaps a geometric midpoint of the surface. An orthographic projection region of the heat source to the surface is located in the central area. The heat dissipation device absorbs heat generated by the heat source through thermal radiation.

## Background
This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 201210427859.1 filed in China, P.R.C. on Oct. 31, 2012, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The disclosure relates to an electronic device, and more particularly to an electronic device having a heat dissipation device.
2. Description of the Related Art
With the constant development of technology, daily necessities increasingly depend on digitization and informatization. For example, many people carry a mobile processing device, such as a notebook or tablet computer, so that they can freely use it in any occasion.
Typically, a set of heat dissipation fins and a fan are disposed in the mobile processing device to remove heat generated by the mobile processing device. Improvements in the arithmetic processing performance of the mobile processing device are typically coupled with corresponding increases in heat generated. To dissipate the additional heat, manufacturers conventionally increase the fan power and the heat dissipation area of the heat dissipation fins, so as to improve the heat dissipation efficiency of the mobile processing device.
Under current trends of technology development, researchers devote significant efforts to continuously developing the mobile processing device toward the objectives of having ever higher performance in ever slimmer and smaller packages. However, increases in fan power and the heat dissipation area of the heat dissipation fins are coupled with increases in the internal volume of the mobile processing device to accommodate the larger heat dissipation fins and high-power fan. This impedes the objective of developing the mobile processing device with a slim design.
SUMMARY OF THE INVENTION
In one embodiment, the disclosure provides an electronic device comprising a housing, a heat source and a heat dissipation device. The heat source is located inside the housing. The heat dissipation device is disposed inside the housing. The heat dissipation device and the heat source are kept apart from each other at a distance. The heat dissipation device comprises a casing having a heat dissipation material. The heat dissipation material comprises 15 to 30 percent volume of a plurality of copper materials, 50 to 85 percent volume of a phase change material, and 15 to 20 percent volume of air. Furthermore, the casing has a surface facing the heat source. A central area and an outer ring area are defined on the surface. The outer ring area surrounds the central area. A geometric midpoint of the central area and a geometric midpoint of the surface overlap each other. The area of the central area is 10% to 50% of the area of the surface. An orthographic projection region of the heat source is located in the central area. The heat dissipation device absorbs heat generated by the heat source through thermal radiation.
In another embodiment, an electronic device comprises a heat source, a housing enclosing the heat source, and a heat dissipation device. The heat dissipation device comprises air and phase change material enclosed within a casing. The air is more compressible than the phase change material so that the air gives up volume to the phase change material as the phase change material changes phase to absorb heat. The casing has a surface spaced apart from the heat source that faces the heat source. Copper tubes are disposed within the casing to distribute heat through the casing.



BRIEF DESCRIPTION OF THE DRAWINGS
The disclosure will become more fully understood from the detailed description given herein below for illustration only, and thus are not limitative of the disclosure, and wherein:
FIG. 1 is a sectional view of an electronic device according to one embodiment of the disclosure;
FIG. 2 is a bottom view of a heat dissipation device in FIG. 1;
FIG. 3 is a bottom view of a heat dissipation device according to another embodiment of the disclosure; and
FIG. 4 is a bottom view of a heat dissipation device according to still another embodiment of the disclosure.



DETAILED DESCRIPTION
The detailed features and advantages of the disclosure are described below in great detail through the following embodiments, the content of the detailed description is sufficient for those skilled in the art to understand the technical content of the present disclosure and to implement the disclosure there accordingly. Based upon the content of the specification, the claims, and the drawings, those skilled in the art can easily understand the relevant objectives and advantages of the disclosure.
Referring to FIG. 1 and FIG. 2, FIG. 1 is a sectional view of an electronic device according to one embodiment of the disclosure, and FIG. 2 is a bottom view of a heat dissipation device in FIG. 1.
An electronic device 10 of this embodiment comprises a housing 11, a heat source 12, and a heat dissipation device 13. In this embodiment and some embodiments, the electronic device 10 may be a tablet computer, a mobile phone, or other electronic products.
A circuit board 14 is disposed in the housing 11. The heat source 12 is disposed on the circuit board 14 and in the housing 11. In this embodiment and some embodiments, the heat source 12 may be an arithmetic processing chip of a tablet computer, a mobile phone, or other electronic elements.
The heat dissipation device 13 is disposed in the housing 11, and the heat dissipation device 13 and the heat source 12 are kept apart from each other at a distance and do not contact each other. The heat dissipation device 13 of the electronic device 10 of the disclosure is capable of absorbing heat generated by the heat source 12 effectively, so as to enable the heat source to operate normally.
The heat dissipation device 13 comprises a casing 131. In this embodiment and some embodiments, the shape of the casing 131 is a cube but not limited thereto. In this embodiment and some embodiments, the material of the casing 131 is, but not limited to, aluminum or copper. A heat dissipation material 132 is disposed in the casing 131. In some embodiments, the heat dissipation material 132 comprises 15 to 30 percent volume of multiple copper materials, 50 to 85 percent volume of a phase change material (when in its low heat phase state), and 15 to 20 percent volume of air. In a more particular embodiment, the heat dissipation material 132 comprises 15 to 20 percent volume of multiple copper materials, 64 to 67 percent volume of a phase change material, and 16 to 17 percent volume of air. In some embodiments, the copper materials are copper tubes, copper partition plates, or other copper members. In some embodiments, the phase change material is, but not limited to, alkanes such as paraffin. The phase change material of this embodiment absorbs heat to change from a solid state to a liquid state. During the process in which the phase change material absorbs the heat to change from the solid state to the liquid state, the temperature of the phase change material maintains the same value and does not rise. After the phase change material changes from the solid state to the liquid state, the volume of the phase change material increases, but the air has excellent compressibility, which provides an extra space for the expansion of the phase change material. The purpose of the air comprised in the heat dissipation material 132 is to address the problem of the increased volume of the phase change material due to the phase change, enabling the space in the casing 131 to accommodate the increased volume of the phase change material.
Moreover, the casing 131 of the heat dissipation device 13 has a surface 1311. The surface 1311 of the heat dissipation device 13 faces the heat source 12. A central area 1312 and an outer ring area 1313 are defined on the surface 1311. The outer ring area 1313 surrounds the central area 1312.
Furthermore, each of the central area 1312, the surface 1311, and the heat dissipation device 13 of this embodiment has a geometric midpoint M. The geometric midpoints M overlap each other. The area of the central area 1312 is preferably 10% to 50% of the area of the surface 1311. In this particular embodiment, the area of the central area 1312 is about 10% of the area of the surface 1311. In some embodiments, the shape of the central area 1312 is a scaled-down, proportionally-reduced version of the shape of the surface 1311. An orthographic projection of the heat source 12 to the surface 1311 is located in region A of the central area 1312. The heat dissipation device 13 absorbs the heat generated by the heat source 12 through thermal radiation.
FIG. 2 illustrates the heat dissipation device 13 of FIG. 1. In this embodiment, the heat dissipation material 132 comprises multiple copper tubes 1321. The copper tubes 1321 are located in the casing 131. The copper tubes 1321 extend from the central area 1312 towards the outer ring area 1313. One copper tube 1321 overlaps with the orthographic projection region A, on the surface 1311 of the heat dissipation device 13 of the heat source 12. This copper tube 1321 also passes through the geometric midpoint M of the heat dissipation device 13. Other copper tubes 1321 extend to four corner portions 1315 of the casing 131 of the heat dissipation device 13 respectively. At least one of the copper tubes 1321 extend to two opposite side edges 1314 of the casing 131 of the heat dissipation device 13. Generally, the copper tubes 1321 extend radially outward from intersection points with the central area 1312 towards the outer ring area 1313 to, or at least near, the perimeter of the outer ring area 1313.
The disclosure is not necessarily limited to the number and the extension manner of the copper tubes 1321 illustrated in this particular embodiment. Persons skilled in the art may design the number and the extension manner of the copper tubes 1321 according to the shape of the heat dissipation device 13 and the position of the heat source 12.
When the heat source 12 transfers heat to the central area 1312 of the heat dissipation device 13 through thermal radiation, the copper tubes 1321 rapidly transfer and disperse the heat from the central area 1312 to the entire outer ring area 1313 of the heat dissipation device 13. The extension of the copper tubes 1321 to the corners of the heat dissipation device 13 spreads the heat more evenly, which in turn enables the entire phase change material in the heat dissipation device 13 to absorb the heat more evenly during phase change, improving the heat absorption efficiency of the heat dissipation device 13. The heat dissipation device 13 of this embodiment may be, but is not required to be, equipped with an exhaust fan, making it useful for thin electronic devices.
As previously noted, the heat dissipation material 132 in the heat dissipation device 13 comprises the phase change material. While undergoing the phase change, the phase change material absorbs heat without increasing the temperature of the phase change material. By selecting an appropriate phase change material, the temperature of the heat dissipation device 13 can be kept for a long time in a comfortable temperature state of between 15 and 45 degrees Celsius. For example, when a phase change material with the phase change temperature being about 37 degrees is selected, the heat dissipation device 13 is capable of being kept at that comfortable temperature for a long time as the phase change material absorbs heat. Therefore, when a user holds the electronic device 10 for a long time, the hand-scalding problem caused by the constant rise of the temperature of the housing 11 of the electronic device 10 incurred by the heat absorption of the heat dissipation device 13 is avoided.
Furthermore, in this embodiment or other embodiments, multiple sets of heat dissipation fins (not shown) may be disposed on the surface of the heat dissipation device 13, so as to further improve the heat absorption efficiency of the heat dissipation device 13.
Referring to FIG. 3, FIG. 3 is a bottom view of a heat dissipation device according to another embodiment of the disclosure.
In this embodiment, multiple copper materials comprised by a heat dissipation material 132 in a heat dissipation device 13a are multiple copper tubes 1321. The copper tubes 1321 are located in a casing 131. The copper tubes 1321 extend from a central area 1312 towards an outer ring area 1313, and each of the copper tubes 1321 and a geometric midpoint M of the heat dissipation device 13a are kept apart from each other at a distance. In other words, in this embodiment, the copper tubes 1321 do not pass through the geometric midpoint M of the heat dissipation device 13a. Furthermore, some of the copper tubes 1321 extend to four corner portions 1315 of the casing 131 of the heat dissipation device 13a respectively, so as to enable heat to be rapidly transferred and dispersed from the central area 1312 to the entire outer ring area 1313 of the heat dissipation device 13a through the copper tubes 1321.
Moreover, a plurality of aluminum partition plates 133 are disposed in the casing 131. In this particular embodiment, the aluminum partition plates 133 are located between the central area 1312 and the outer ring area 1313, so as to form a rectangular frame body, thereby separating the central area 1312 from the outer ring area 1313. Furthermore, a copper tube 1321 extends from each corner portion of the rectangular frame body formed by the aluminum partition plates 133 to a corresponding corner portions 1315 of the casing 131 respectively. The positions where the aluminum partition plates 133 are disposed in the casing 131 of this embodiment are not intended to limit the disclosure. Furthermore, the volume percent of the aluminum partition plates 133 is less than 3% of the volume percent of the copper tubes 1321, so as to prevent the heat absorption effect of the heat dissipation device 13a from being lowered.
In addition, by disposing the aluminum partition plates 133, the interior of the casing 131 is divided into at least two areas, so as to ensure that the phase change material of each area in the casing 131 is evenly distributed. Thus, the problem that the heat absorption efficiency of the heat dissipation device 13a is affected by uneven distribution of the phase change material due to accumulation of the phase change material in a specific area (for example, the bottom) in the casing 131 incurred by multiple phase changes and the influence of gravity may be avoided.
When a heat source 12 transfers heat to the central area 1312 of the heat dissipation device 13a through thermal radiation, the phase change material in the central area 1312 absorbs the heat to undergo phase change first. Meanwhile, the phase change material in the central area 1312 quickly transfers and disperses the absorbed heat from the central area 1312 to the entire outer ring area 1313 of the heat dissipation device 13a through the copper tubes 1321 and the aluminum partition plates 133. Therefore, all corners of the heat dissipation device 13a can receive the heat evenly, so as to enable the entire phase change material in the heat dissipation device 13a to absorb the heat evenly to undergo phase change, thereby improving the heat absorption efficiency of the heat dissipation device 13a. 
Referring to FIG. 4, FIG. 4 is a bottom view of a heat dissipation device according to still another embodiment of the disclosure.
In this embodiment, multiple copper materials comprised by a heat dissipation material 132 in a heat dissipation device 13b are multiple copper tubes 1321 and multiple copper partition plates 1322. The copper tubes 1321 and the copper partition plates 1322 are located in a casing 131. The copper tubes 1321 extend from a central area 1312 towards an outer ring area 1313, and each of the copper tubes 1321 and a geometric midpoint M of the heat dissipation device 13b are kept apart from each other at a distance. In other words, in this embodiment, the copper tubes 1321 do not pass through the geometric midpoint M of the heat dissipation device 13b. Furthermore, the copper partition plates 1322 surround the geometric midpoint M of the heat dissipation device 13b, so as to form a rhombic frame body. The copper tubes 1321 extend from all corner portions of the rhombic frame body formed by the copper partition plates 1322 to all side edges 1314 of the casing 131 respectively.
Therefore, by disposing the copper partition plates 1322, the interior of the casing 131 is divided into at least two areas, so as to ensure that the phase change material of each area in the casing 131 is evenly distributed. Thereby, the problem that the heat absorption efficiency of the heat dissipation device 13b is affected by uneven distribution of the phase change material due to accumulation of the phase change material in a specific area (for example, the bottom) in the casing 131 incurred by multiple phase changes and the influence of gravity may be avoided.
When a heat source 12 transfers heat to the central area 1312 of the heat dissipation device 13b through thermal radiation, the phase change material in the central area 1312 absorbs the heat to undergo phase change first. Meanwhile, the phase change material in the central area 1312 quickly transfers and disperses the absorbed heat from the central area 1312 to the entire outer ring area 1313 of the heat dissipation device 13b through the copper tubes 1321 and the copper partition plates 1322. Therefore, all corners of the heat dissipation device 13b can receive the heat evenly, so as to enable the entire phase change material in the heat dissipation device 13b to absorb the heat evenly to undergo phase change, thereby improving the heat absorption efficiency of the heat dissipation device 13b. 
According to the electronic device of the embodiment, the heat dissipation material comprises 15 to 30 volume percent of copper materials, 50 to 85 volume percent of the phase change material, and 15 to 20 volume percent of air, so as to enable the heat to be quickly transferred and dispersed to the entire heat dissipation device through the copper materials. Therefore, the entire phase change material in the heat dissipation device can absorb the heat evenly to undergo the phase change, so as to improve the heat absorption efficiency of the heat dissipation device. Moreover, the heat dissipation material comprises the phase change material, so that in the heat absorption process of the heat dissipation device, the temperature of the heat dissipation device is capable of being kept for a long time in a comfortable temperature state for holding. Furthermore, the heat dissipation device of this embodiment is not required to be equipped with an exhaust fan, so that the heat dissipation device of this embodiment is applicable to a thin electronic device, and can reduce the generation of noise.
The foregoing description of the exemplary embodiments of the disclosure has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.
The embodiments were chosen and described in order to explain the principles of the disclosure and their practical application so as to activate others skilled in the art to utilize the disclosure and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the disclosure pertains without departing from its spirit and scope. Accordingly, the scope of the disclosure is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.

## Claims

1. An electronic device, comprising:
a housing;
a heat source located in the housing; and
a heat dissipation device disposed in the housing, the heat dissipation device and the heat source being kept apart from each other at a distance, the heat dissipation device comprising a casing and a heat dissipation material disposed in the casing, the heat dissipation material comprising 15 to 30 percent volume of a plurality of copper materials, 50 to 85 percent volume of a phase change material, and 15 to 20 percent volume of air, wherein the phase change material comprises an alkane;
wherein the casing has a surface facing the heat source, a central area and an outer ring area are defined on the surface, the outer ring area surrounds the central area, a geometric midpoint of the central area and a geometric midpoint of the surface overlap, the area of the central area is 10 percent to 50 percent of the area of the surface, an orthographic projection of the heat source to the surface forms an orthographic projection region located in the central area, and the heat dissipation device absorbs heat generated by the heat source through thermal radiation.

2. The electronic device according to claim 1, wherein the copper materials extend from the central area towards the outer ring area.

3. The electronic device according to claim 2, wherein the copper materials are a plurality of copper tubes or a plurality of copper partition plates, and at least one of the copper materials and the orthographic projection region of the heat source overlap.

4. The electronic device according to claim 2, wherein at least one of the copper materials passes through a geometric midpoint of the heat dissipation device.

5. The electronic device according to claim 2, wherein each of the copper materials and a geometric midpoint of the heat dissipation device are spaced apart from each other.

6. The electronic device according to claim 2, wherein respective ones of the copper materials extend to each corner portion or each side edge of the casing of the heat dissipation device.

7. The electronic device according to claim 1, wherein a plurality of aluminum partition plates is disposed in the casing, and the volume of the aluminum partition plates is less than 3 percent of the volume of the copper materials.

8. The electronic device according to claim 7, wherein the aluminum partition plates surround a geometric midpoint of the heat dissipation device, the copper materials are a plurality of copper tubes, and a copper tube extends from each corner portion of the aluminum partition plates to each corresponding corner portion of the casing.

9. The electronic device according to claim 1, wherein the copper materials are a plurality of copper partition plates and a plurality of copper tubes, the copper partition plates surround a geometric midpoint of the heat dissipation device, and a copper tube extends from each corner portions of the copper partition plates to a corresponding side edge of the casing.

10. An electronic device comprising:
a heat source;
a housing enclosing the heat source;
a heat dissipation device comprising air and phase change material enclosed within a casing, wherein the air is more compressible than the phase change material so that the air gives up volume to the phase change material as the phase change material changes phase to absorb heat;
the casing having a surface spaced apart from the heat source that faces the heat source; and
copper tubes disposed within the casing to distribute heat through the casing.

11. The electronic device according to claim 10, wherein the phase change material changes phase between a solid state and a liquid state at a temperature between 15 and 45 degrees.

12. The electronic device according to claim 10, wherein the phase change material comprises an alkane.

13. The electronic device according to claim 10, wherein the phase change material comprises paraffin.

14. The electronic device according to claim 10, wherein the air in the heat dissipation device takes up at least 15 percent of the volume of the heat dissipation device when the phase change material is in a low heat phase state.

15. The electronic device according to claim 10, wherein the copper tubes take up at least 15 percent of the volume of the heat dissipation device.

16. The electronic device according to claim 10, wherein an orthographic projection region of the heat source is centered on the casing surface that faces the heat source.

17. The electronic device according to claim 16, wherein the copper tubes intersect a central area of the heat dissipation device and extend outwardly from the central area toward a perimeter of the casing.

18. The electronic device according to claim 10, further including at least one partition within the casing that partitions the heat dissipation device into at least two regions, each region containing air and phase change material.

19. The electronic device according to claim 10, further comprising copper partition plates that form a rhombic body about a midpoint of the casing surface.