Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
1999-01-13
2001-04-03
Thorpe, Timothy S. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C361S697000, C165S080300
Reexamination Certificate
active
06210134
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cooling devices and the cooling-fan-motors thereof employed in electronic apparatuses having slim bodies.
BACKGROUND OF THE INVENTION
In the conventional slim electronic apparatus as shown in
FIG. 8
, printed wired assembly substrates
3
(hereinafter referred to as PWAs) are placed. On the PWAs, heat generating components
2
such as semiconductors and a CPU are mounted. The heat generated from components
2
travels through heat conductive member
6
such as an aluminum plate, and is discharged outside the apparatus. The discharged heat amount is calculated with the following expression.
Q out ∝ &Sgr;(Tsi−Ta) ×Si
where:
Q out=discharged heat amount
Tsi=a temperature at an “i” th cell of the housing surface, which is finely divided into cells
Si=an area of the “i” th cell
Ta=outer temperature
Accordingly, the housing temperature rises and an area of high temperature increases as greater built-up heat amounts are produced by the components.
When this structure is employed in an electronic apparatus such as a mobile computer or a digital video camera, the interior built-up heat could potentially damage its internal electronic operating components. Further, since these apparatus are held by a user's hand during operation, the temperature rise on the housing surface makes the user uncomfortable. Therefore, it has been proposed to discharge the interior built-up heat forcibly outside the apparatus by providing a cooling fan in the apparatus.
In the prior art depicted in
FIGS. 9A and 9B
, components
2
that generate heat, such as semiconductors, are mounted on a PWA
3
that is installed in housing
1
. On one of inside faces of housing
1
, cooling fan
5
is provided. The height of fan
5
is substantially equal to that of a housing
1
and frame
4
of fan
5
functions as a heat sink. The heat produced by components
2
travels to fan
5
via heat conductive member
6
made of e.g. aluminum. Then fan
5
drives blades
7
to forcibly discharge the heat outside the apparatus.
FIG. 10
is a cross section of an essential part of another electronic apparatus with a conventional cooling fan. In
FIG. 10
, a plurality of PWAs accommodating heat generating components
2
such as semiconductors are installed in the housing
1
. PWA
3
installed at the lowest place in housing
1
is shortened at its end in order to provide a space between PWA
3
and a side of the housing. In this space, flat cooling fan
8
is disposed so that its shortest side extends in the height direction of the apparatus. The frame of fan
8
functions as a heat sink. The heat produced by components
2
travels to fan
8
via heat conductive member
6
made of e.g. aluminum. Then fan
8
forcibly discharges the heat outside the apparatus. The structure in
FIG. 10
mentioned above is employed in a large number of slim notebook-type personal computers. In addition to ensuring reliability of the personal computers, it is desirable that the height of cooling fan
8
be as low as ca. 7.5 mm so that the total housing height of the apparatus should be less than 20 mm.
The structure in
FIG. 9
is compared with that in
FIG. 10
to find the following fact. The structure in
FIG. 9
can be employed in the electronic apparatuses such as notebook type personal computer of which total height ranges from 25 to 40 mm. However, in the case of mobile computers requiring a further compact and slim body, the height of cooling fan
5
, i.e. 2 ×(a+b+c) becomes a possible obstacle to meeting requirements.
where “a”=radius of motor, “b”=blade height, “c”=frame thickness
The height of an electronic apparatus that requires an extra slim body is often restricted by the height of cooling fan
5
. In order to reduce the height of fan
5
, each dimension mentioned above, i.e. “a”, “b” and “c” should be reduced; however, the following inconveniences accompany this reduction:
Reduction of dimension “a”: decreasing the motor power and lowering the motor efficiency;
Reduction of dimension “b”: decreasing the air volume; and
Reduction of dimension “c”: degrading the strength of the frame; and weakening the heat sink function,
The height of cooling fan
5
is thus cannot readily lowered, which has been an obstacle to further downsizing of compact electronic apparatuses such as mobile personal computers.
The structure shown in
FIG. 10
has been proposed to overcome the problem of the structure shown in FIG.
9
. However, in the case of compact electronic apparatuses such as a mobile personal computers this structure of
FIG. 10
still has the following problem. Two sheets of double sided PWA accommodate the components. Assume that each PWA measures 50 mm×100mm Then the total components-mounting-area is thus 50 mm×100 mm×2 sides×2 sheets=20000 mm
2
.
In order to dispose a fan
8
that measures 40 mm×40 mm, one PWA 3 should be cut out, which reduces the components-mounting-area by 40 1mm×40 mm×2 sides=3200 mm
2
. As a result, the total components-mounting-area is reduced by 16%.
This area-reduction decreases the number of components which can be mounted, and has been an obstacle to realizing compact size electronic apparatus having high performance and versatile functions.
SUMMARY OF THE INVENTION
The present invention addresses the problems above and aims to provide a compact and high performance cooling-device for electronic apparatuses requiring a cooling fan and a fan motor whereby the apparatuses can be thin in size and for which a reduction of the component-mounting-area can be minimized.
An arrangement according to the present invention utilizes:
(a) PWAs including heat-generating electronic components such as semiconductors, and being disposed in a housing of a thin-type electronic apparatus, such as a mobile personal computer or a digital video camera, so that a given space is provided between the housing and the PWAs;
(b) a cooling fan motor having a small and tubular case made of heat-conductive materials such as copper, aluminum and the like, the cooling fan motor having a height smaller than the height of the housing, and being disposed in the given space provided in the housing; and
(c) an air discharge opening through which the heated air in the housing is discharged.
This structure described above allows the cooling fan motor to reduce its occupying space in the housing. The cooling fan thus can be placed to function efficiently. The build-up heat in the housing can be satisfactorily dissipated, which permits the interior components to be sufficiently cooled down. As a result, the structure according to the present invention can allows the electronic apparatuses such as mobile personal computers and digital video computers to be slimmed down without degrading cooling efficiency or decreasing the components-mounting-area.
REFERENCES:
patent: 3149666 (1964-09-01), Coe
patent: 5382092 (1995-01-01), Okamoto et al.
patent: 5445215 (1995-08-01), Herbert
patent: 5917699 (1999-06-01), Hung et al.
patent: 6031721 (2000-02-01), Bhatia
patent: 6075698 (2000-06-01), Hogan et al.
patent: 7-111302 (1995-04-01), None
patent: 8-274481 (1996-10-01), None
Matsushita Electric Industrial Co. Ltd
Thorpe Timothy S.
Torrente David J.
Wenderoth , Lind & Ponack, L.L.P.
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