Heat exchange – With retainer for removable article – Electrical component
Reexamination Certificate
1999-06-22
2001-06-05
Lazarus, Ira S. (Department: 3743)
Heat exchange
With retainer for removable article
Electrical component
C165S185000, C361S688000, C361S689000, C361S695000, C361S700000, C257S714000, C174S015200
Reexamination Certificate
active
06241007
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic apparatus such as a portable computer, and more particularly to a structure for cooling the heat-generating components provided in such an electronic apparatus.
In recent years, portable electronic apparatuses, represented by book-like portable computers and mobile information apparatuses, have been developed. Each of these apparatuses incorporates a high-speed MPU (Microprocessing Unit) and has various functions in order to process multimedia information, such as characters, speech, sound, and images. The higher the integration density it has, and the more functions it performs, the more electric power the MPU consumes while operating. The more electric power it consumes, the more heat the MPU generates. In the case of a portable computer incorporating an MPU, the heat generated by the MPU must be radiated efficiently from the MPU in the housing of the portable computer. It is therefore absolutely necessary to provide a cooling unit in the housing to cool the MPU positively.
A conventional system for cooling an MPU will be described, with reference to FIG.
25
. As shown in
FIG. 25
, an MPU
2
is mounted on a circuit board
1
provided in the housing (not shown) of a portable computer. A cooling unit
3
for cooling the MPU
2
is provided on the upper surface of the circuit board
1
.
The cooling unit
3
comprises a flat heat sink
4
and an electric fan device
5
. The heat sink
4
is made of metal having high thermal conductivity, such as aluminum alloy. The heat sink
4
is thermally connected to the MPU
2
. Hence, heat can be conducted from the MPU
2
to the heat sink
4
. The heat sink
4
has a number of radiation fins
6
on the upper surface, which faces away from the MPU
2
. The radiation fins
6
extend in the direction of thickness of the heat sink
4
and are exposed in the housing of the portable computer.
The electric fan device
5
is arranged at one end of the heat sink
4
. The device
5
comprises a fan casing
7
and a fan
8
. The fan casing
7
has an air passage
7
a.
The fan
8
is provided in the air passage
7
a.
The fan device
5
is vertically positioned and secured to the heat sink
4
, and the rotation axis O
1
of the fan
8
extends horizontally. The inlet end of the air passage
7
a
faces the radiation fins
6
, whereas the outlet end of the passage
7
a
faces the exhaust port of the housing.
When the fan
8
is driven and rotated, a stream of cooling air is generated in the housing, flowing toward the heat sink
4
. The cooling air then flows along the heat sink
4
and the radiation fins
6
. Finally, the air is exhausted from the housing through the exhaust port of the housing. The convection of cooling air, occurring in the housing, cools the heat sink
4
. Thus, the heat transmitted from the MPU
2
to the heat sink
4
is expelled from the housing.
A prominent commercial value of portable electronic apparatuses, such as portable computers, is their portability. This is why the housings of portable computers are getting thinner and lighter recently, so that they may be put into bags and the like. The above-described cooling unit
3
, which incorporated in the housing of the portable computer, should also be made thinner and lighter.
However, the conventional cooling unit
3
can hardly be rendered lighter for the following reason. As mentioned above, the heat sink
4
is cooled by virtue of the convection of cooling air. The cooling ability of the unit
3
is therefore determined by the surface area of the heat sink
4
and the flow rate of the cooling air supplied by the fan device
5
. In order to increase the cooling ability, the heat sink
4
must be larger and more radiation fins
6
must be provided. Consequently, the cooling unit
3
must be heavier.
To make matters worse, the conventional cooling unit
3
must be rather thick. This is because the fan device
5
is vertically positioned and secured to the heat sink
4
and the rotation axis O
1
of the fan
8
extends horizontally. The fan casing
7
inevitably project upward for a long distance from the heat sinks
4
.
As a consequence, the higher the cooling ability of the unit
3
, the thicker, larger and heavier the cooling unit
3
should be. Any portable computer that incorporates a thick cooling unit can hardly be as thin as is desired.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide an electronic apparatus in which a heat-generating component, such as an MPU, can acquire a sufficient cooling ability and whose housing can yet be as thin as is desired.
To attain the object, an electronic apparatus according to the first aspect of the invention comprises: a housing; a heat-generating component provided in the housing; and a heat sink including a first metal plate and a second metal plate, for cooling the heat-generating component. The first metal plate having a heat receiving portion thermally connected to the heat-generating component. The second metal plate being laid on the first metal plate and thermally connected thereto.
When the electronic apparatus is used, the heat-generating component generates heat. The heat is transmitted to the heat receiving portion of the first metal plate. The heat then diffuses into the entire heat sink. The first metal plate is laid on the second metal plate. If the second metal plate has a higher thermal conductivity than the first metal plate, it can efficiently transmit the heat to every part of the first metal plate from the heat receiving portion.
The first metal plate may be thicker to have a larger thermal capacity or a lower thermal resistance in order to achieve efficient conduction of heat by using the first metal plate only. However, the thicker the plate, the thicker and heavier the heat sink. Consequently, the housing may not be as thin as desired.
Nonetheless, the second metal plate transfers the heat from the heat receiving portion with high efficiency. No heat spots are formed in the limited part of the first metal plate. The heat can be efficiently radiated, without necessity of making the first metal plate thicker. As a result, the heat sink can be made thin, and ultimately the housing can be made thin.
Various types of metal plates may be prepared, each different in size and shape or in size, and one type that can best transfer the heat generated by the heat-generating component may then be selected and used as the second metal plate. In this case, heat will be transferred from the heat-generating component to the heat sink, neither too much nor too little.
To accomplish the object described above, an electronic apparatus according to the second aspect of the invention comprises: a housing; a heat-generating component provided in the housing; and a cooling unit for cooling the heat-generating component. The cooling unit comprises a heat sink, a fan device, and a heat pipe. The heat sink has a heat receiving portion thermally connected to the heat-generating component and a heat exchanging portion formed integral with the heat receiving portion. The fan device is arranged at the heat exchanging portion and includes a fan facing the heat exchanging portion, for applying cooling air to the heat exchanging portion, and a fan casing having an air outlet port for expelling the cooling air. The heat pipe transfers heat generated by the heat-generating component, from the heat receiving portion to the heat exchanging portion. The heat pipe has a heat-radiating portion that faces the air outlet port.
When the electronic apparatus is used, the heat-generating component generates heat. The heat is transmitted to the heat receiving portion of the heat sink and hence to the heat exchanging portion and diffuses in the entire heat sink. Part of the heat conducted to the heat receiving portion is positively transferred through the heat pipe to the heat exchanging portion. Thus, the heat is transferred from the heat receiving portion to the heat exchanging portion through various passages, with high efficiency.
When the fa
Kitahara Chihei
Nakamura Hiroshi
Shibasaki Kazuya
Ubukata Hiroshi
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Lazarus Ira S.
McKinnon Terrell
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