Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-12-22
2001-06-05
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C165S121000, C165S122000, C165S104330, C165S080300, C174S015200, C361S700000, C415S178000, C417S423120
Reexamination Certificate
active
06243263
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to a heat radiation device for a thin electronic apparatus, and more particularly, to a heat radiation device for a thin electronic apparatus which is adapted to radiate to the outside heat generated from a thin electronic apparatus such as an electronic apparatus having the size of a credit card and which is suitable for radiation of heat from a thin electronic apparatus accommodated within a limited space.
BACKGROUND ART
Recently, portable data processing apparatuses, such as laptop personal computers, have been improved in terms of processing performance and have been made thinner. Therefore, such a data processing apparatus incorporates a high performance CPU, which consumes much power and generates a great amount of heat. Therefore, there have been devised various methods for radiating to the outside heat from a heat source such as a high performance CPU. Meanwhile, improvements have been made to such a high performance CPU itself in order to cope with heat generation; e.g., employment of a low-power consumption mode and employment of a design that enables low-voltage drive.
Means for circulating cooling air by use of a fan has been the most commonly used method for radiating to the outside heat from a heat source such as a high performance CPU that constitutes the above-mentioned data processing apparatus. That is, outside air is taken into a heat radiation device attached to a heat source, is passed through the interior of the heat radiation device, and is discharged to the outside of the heat radiation device. However, since the heat radiation apparatus itself has a reduced thickness, cooling air does not flow smoothly through the interior of the heat radiation device. Since the non-smooth flow of cooling air decreases the cooling efficiency of the heat radiation device, heat from the heat source cannot be effectively radiated to the outside. Further, since the cooling air flows through a limited narrow space within the heat radiation device, a portion of air to be discharged is not discharged from the heat radiation device. That is, a portion of air that must be discharged to the outside is again taken into the interior of the heat radiation device, thus further decreasing the cooling efficiency.
Cooling performance can be improved through an increase in the flow rate of cooling air. However, since this measure requires an increase in the size of a fan, the overall thickness of the heat radiation device or the data processing apparatus cannot be decreased. Practically, since a space for accommodating a large fan cannot be secured in a thin heat radiation device and a thin data processing apparatus, the above-described measure cannot be employed.
An object of the present invention is to provide a heat radiation device for a thin electronic apparatus which can improve cooling efficiency without rendering difficult decreasing the thickness of a data processing apparatus.
SUMMARY OF THE INVENTION
A heat radiation device for a thin electronic apparatus according to the present invention comprises a rectangular plate-shaped base formed from a material having high heat conductivity, a rectangular intermediate plate formed from a material of high heat conductivity and stacked on the base, a rectangular box-shaped cover stacked on the intermediate plate, and a fan. A depression having a short cylindrical shape is formed at a center portion of the base. A plurality of parallel fins are projected from the bottom portion of the base along a first longer side thereof such that the fins extend in a direction perpendicular to the first longer side, whereby a second ventilation port is formed. A communication portion having an arcuate shape as projected on a plane is formed in order to connect the depression and the second ventilation port. A circular opening is formed in the intermediate plate at a position corresponding to that of the depression. A fan is attached to the circular opening. The intermediate plate and the base are connected together such that heat can be conduced therebetween. A downwardly projecting side plate is provided at each longer side of the cover. When the end surface of the side plate is brought into contact with the intermediate plate and/or the base, a first ventilation port for cooling air is formed at a shorter side of the cover, and a passage for cooling air is formed between the cover and the intermediate plate. When the fan is operated, cooling air is caused to flow between the first and second ventilation ports, so that heat accumulated within the base is radiated to the outside.
In the heat radiation device for a thin electronic apparatus according to the present invention, since cooling air is caused to flow at a high flow speed along a predetermined passage within the heat radiation device, heat can be efficiently taken in and discharged from a thin electronic apparatus including a heat source such as a high performance CPU that consumes a large amount of power and generates a large amount of heat. By virtue of the above-described structure, heat can be radiated efficiently from even a thin heat radiation device which has a reduced thickness and through which cooling air does not flow smoothly because of the reduced thickness. Especially, since the above-described structure of the heat radiation device increases the flow velocity of cooling air, a thin electronic apparatus, which may generate the largest amount of heat among various types of electronic apparatuses, can be efficiently cooled by air through forced flow of cooling air. Accordingly, a thin electronic apparatus can be effectively air-cooled without necessity of increasing the size of the fan of the heat radiation device. Also, the heat radiation device does not hinder an data processing apparatus from being made thinner.
In one preferred embodiment of the present invention, a first ventilation port is used as an intake port, and a second ventilation port is used as a discharge port. Cooling air is caused to flow from the first ventilation port to the second ventilation port through operation of the fan.
In another preferred embodiment of the present invention, the bottom surface of the base is used as a heat receiving portion, which is disposed above a heat source to face the heat source. This structure enables efficient conduction of heat from the heat source to the base, so that cooling efficiency is improved.
In still another preferred embodiment of the present invention, the bottom surface of the base serving as a heat receiving portion that faces the heat source is covered with a thin film of a material of high heat conductivity. When the base is formed of an aluminum alloy, a copper (Cu) layer and a nickel (Ni) layer are layered, in this sequence, on the bottom surface of the base. This structure enables efficient absorption of heat from a heat source to thereby further improve cooling efficiency.
In yet another preferred embodiment of the present invention, a groove having a semi-circular or U-shaped cross section is formed in the base, along a shorter side and a longer side thereof. A condensation portion of a heat pipe is accommodated within the groove in a heat conductible manner, and an evaporation portion of the heat pipe is connected to the heat source in a heat conductible manner. By virtue of this structure, when no space is secured above the heat source, heat from the heat source can be conducted to a heat radiation device provided in a large space within the data processing apparatus and is treated there. Accordingly, cooling efficiency can be improved, while the thinness of the overall data processing apparatus is secured.
In still another preferred embodiment of the present invention, insertion holes are formed in the intermediate plate, some or all of the fins provided on the base have insertion portions provided at their upper ends, and the insertion portions are fitted into the insertion holes. This structure promotes heat conduction between the base and the intermediate plate, so that occurrence of thermal
PFU Limited
Thompson Gregory
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