U.S. patent application number 09/057339 was filed with the patent office on 2002-05-02 for electronic equipment.
Invention is credited to EISHIMA, MASAAKI, KONDO, YOSHIHIRO, NAGANAWA, TAKASHI, NAKAGAWA, TSUYOSHI, NAKAJIMA, TADAKATSU, OHASHI, SHIGEO.
Application Number | 20020051339 09/057339 |
Document ID | / |
Family ID | 14141566 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020051339 |
Kind Code |
A1 |
OHASHI, SHIGEO ; et
al. |
May 2, 2002 |
ELECTRONIC EQUIPMENT
Abstract
An electronic equipment includes a first casing on which are
mounted a keyboard and a wiring board and a second casing which is
rotatably mounted on the first casing by means of a hinge. The
cooling structure of the electronic equipment includes one or more
elements that is the subject of cooling arranged within the first
casing, a first heat-discharging member thermally connected with
this element and the first casing, a second heat-discharging member
that is arranged in the interior of the second casing, and
connection means for thermally connecting the first
heat-discharging element and the second heat-discharging
element.
Inventors: |
OHASHI, SHIGEO;
(TSUCHIURA-SHI, JP) ; NAGANAWA, TAKASHI;
(IBARAKI-KEN, JP) ; NAKAJIMA, TADAKATSU;
(IBARAKI-KEN, JP) ; NAKAGAWA, TSUYOSHI;
(HADANO-SHI, JP) ; EISHIMA, MASAAKI; (EBINA-SHI,
JP) ; KONDO, YOSHIHIRO; (NIIHARI-GUN, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
14141566 |
Appl. No.: |
09/057339 |
Filed: |
April 9, 1998 |
Current U.S.
Class: |
361/679.46 |
Current CPC
Class: |
G06F 1/203 20130101;
G06F 2200/203 20130101 |
Class at
Publication: |
361/687 |
International
Class: |
H05K 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 14, 1997 |
JP |
09-095581 |
Claims
What is claimed is:
1. An electronic equipment including a first casing on which are
mounted a keyboard and a wiring board, and a second casing
accommodating a display device and rotatably mounted on said first
casing by means of a hinge, the equipment comprising: one or more
elements that are a subject of cooling arranged within said first
casing; a first heat-discharging member thermally connected with
said element and said first casing; a second heat-discharging
member arranged within said second casing; and connection means for
thermally connecting said first heat-discharging member and said
second heat-discharging member.
2. The electronic equipment according to claim 1, further
comprising a flexible thermally conductive member provided between
said element that is the subject of cooling and said first
heat-discharging member.
3. The electronic equipment according to claim 1 or 2, further
comprising a heat-discharging member arranged between said element
that is the subject of cooling, said keyboard and/or the bottom
surface of the casing and thermally contacting said element that is
the subject of cooling, said keyboard and/or the bottom surface of
the casing.
4. The electronic equipment according to claim 1, wherein said
connection means also serves as said hinge.
5. The electronic equipment according to claim 1, wherein said
connection means comprises a thermally conductive member that is
connected by contacting said first heat-discharging member and said
second heat-discharging member.
6. The electronic equipment according to claim 5, wherein said
connection means comprises a thermally conductive member comprising
one or other of a thermally conductive member connected to said
first heat-discharging member and a thermally conductive member
connected to said second heat-discharging member and is connected
in contact with these thermally conductive members.
7. The electronic equipment according to claim 5 or 6, wherein the
size of the region of contact of said means for contact is
adjustable.
8. An electronic equipment including a first casing on which are
mounted a keyboard and a wiring board, and a second casing
accommodating a display device and rotatably mounted on said first
casing by means of a hinge, the equipment comprising: one or more
elements that are a subject of cooling arranged within said first
casing; a thermally conductive member thermally connected with this
element and the surface of said first casing; and connection means
for thermally connecting said first casing and said second
casing.
9. The electronic equipment according to claim 8, wherein said
connection means also serves as said hinge.
10. An electronic equipment including a first casing on which are
mounted a keyboard and a wiring board, and a second casing
accommodating a display device and rotatably mounted on said first
casing by means of a hinge, the equipment comprising: a first heat
discharging path from one or more elements that are a subject of
cooling arranged within said first casing to a bottom surface
thereof through a heat-discharging member of the bottom surface of
said first casing; a second heat discharging path from said element
that is the subject of cooling to said keyboard through said first
heat-discharging member thermally connected with this element and
the bottom surface of said first casing; and a third heat
discharging path from said first heat-discharging member to said
second casing through connection means for thermally connecting
said first heat-discharging member with a second heat-discharging
member arranged in said second casing.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an electronic equipment
including a first casing provided with a circuit board on which is
mounted a heat-emitting element and a heat-discharging sheet that
discharges heat from this element, and a second casing
accommodating a display device and that is rotatably mounted on the
first casing, and more particularly relates to an electronic
equipment provided with a cooling structure.
[0003] 2. Description of the Related Art
[0004] As disclosed in Japanese Patent Unexamined Publication No.
7-142886 and Japanese Patent Unexamined Publication No. 8-162576,
in examples of the related art in the above technical field, heat
is transported from a first casing mounting a heat-emitting element
to a second casing accommodating a display device etc. and is
discharged from the walls of the second casing.
[0005] In Japanese Patent Unexamined Publication No. 7-142886
(Prior art 1), a heat-discharging member mounted on a heat-emitting
element accommodated in a casing, and a heat-discharging member
provided in a second casing that accommodates a display device etc.
are connected by a flexible tube and the heat-emitting element is
cooled by driving cooling liquid between the respective
heat-discharging members.
[0006] On the other hand Japanese Patent Unexamined Publication No.
8-162576 (Prior art 2) discloses a technique in which a hinge that
connects a first casing mounting a heat-emitting element and a
second casing accommodating a display device etc. is formed of
material having high thermal conductivity and a heat-discharging
member mounted on a heat-emitting element and a heat-discharging
member provided in the second casing and the hinge are thermally
connected by means of a high conductivity member, thereby allowing
heat transfer to be performed to the second casing so as to
increase the area from which the heat from the heat-emitting
elements can be discharged.
[0007] Currently, in electronic equipments such as portable
personal computers, with increased heat emission of the elements
due to upgrading of performance, together with advances in
reduction in casing thickness and weight and since these electronic
equipments are usually battery-driven, it has become necessary to
achieve reductions in power consumption of the equipment as a
whole.
[0008] In Prior art 1, motive power is required in order to drive
the liquid. The problem was therefore not considered that this
would lead to increased power consumption for the liquid drive and
increased weight for the liquid drive device, which result in
disadvantages from the point of view of portability. In contrast,
prior art 2 was applicable only to a specific heat-emitting
element, and if a plurality of heat-emitting elements were to be
cooled, a heat path to the hinge had to be provided in respect of
each heat-emitting element. Furthermore, in order to decrease the
thermal resistance from the heat-emitting element to the hinge, it
was necessary to arrange the heat-emitting element and hinge
adjacent each other. That is, it was not taken into consideration
that an obstacle to obtaining higher performance of the system as a
whole was presented by the restrictions in layout on the wiring
board of the heat-emitting element due to considerations regarding
space for the heat path and distance to the hinge, in order to
suppress temperature rise of all the heat-emitting elements and
also to suppress temperature rise of casing surfaces such as the
keyboard.
[0009] Also, in the case of electronic equipments for which
portable use is a presupposition, it is necessary not only that the
temperature of the keyboard mounted on the casing should be in a
suitable range, but also that of device surfaces of the casing that
come into frequent direct contact with the user (for example when
the equipment is used resting on the knees or legs etc.). However,
the problem was not considered that, with increase in the amount of
heat resulting from upgraded performance of the elements, rise in
temperature occurs of the casing in the vicinity of the location
where the elements are mounted, the keyboard mounted on the casing
and/or the back surface of the display device whereby heat is
transmitted as in the case of prior art 2, giving rise to
discomfort of the user. In other words, it was not taken into
consideration appropriate distribution of the heat generated to the
equipment is needed when the amount of heat generated within the
casing increased, in order to guarantee performance by cooling the
elements and to keep the temperature of the casing and/or keyboard
in a range comfortable for the user during operation.
[0010] Furthermore, due to reasons of cost of components and
improvement of performance in the case of maintenance or repair
etc., in such portable electronic equipment, the system
specification may be altered and, accompanying this, the layout of
the elements and/or equipment within the casing is often altered;
when this is done, the problem arises that large alterations have
to be made to the cooling structure, so that production cost is
raised and furthermore improved performance is prevented if a
sufficient cooling performance cannot be ensured. In particular,
consideration was not given to the problem that, in the case of a
liquid crystal device typically employed in a display device
mounted on a second casing, there are restrictions on the
temperature of the device in order to ensure proper display
performance, so that proper display performance cannot be achieved
unless the amount of heat transmitted to the second casing is
regulated such that, in coping with alterations and performance
upgrades of the system specification, the upper limit of the
display temperature is not exceeded.
SUMMARY OF THE INVENTION
[0011] An object of the present invention is to provide an
electronic equipment having a cooling structure suited to
small-thickness light-weight casings whereby rise in temperature of
the surface of the casing accommodating a heat-emitting element and
a keyboard etc. can be suppressed and the temperature of the
heat-emitting element can be cooled to a predetermined temperature,
with no discomfort to the operator, irrespective of the layout on
the wiring board of the heat-emitting element and/or the layout of
equipment items within the casing.
[0012] A further object of the present invention is to provide an
electronic equipment having a cooling structure capable of
maintaining the casing and keyboard at a temperature at which there
is no discomfort to the operator whilst the heat-emitting element
is maintained below a predetermined temperature and the amount of
heat generated from the heat-emitting element and/or device within
the casing is suitably dispersed in the entire equipment.
[0013] Yet a further object is to provide an electronic equipment
having a cooling structure whereby the amount of heat emitted from
the casing can be regulated to cope with changes in the layout of
heat-emitting elements and/or equipment within the casing.
[0014] In order to solve the above problems, an electronic
equipment according to the present application comprises a first
casing on which are mounted a keyboard and a wiring board, and a
second casing accommodating a display device and rotatably mounted
on the first casing by means of a hinge, and further comprises a
first heat-discharging member thermally connected with one or more
elements that are the subject of cooling arranged within the first
casing and the surface of the first casing, a second
heat-discharging member arranged within the second casing, and
means for connection that thermally connects the first and the
second heat-discharging members. Further, there is provided a
construction comprising a flexible thermally conductive member
provided between the element that is the subject of cooling and the
first heat-discharging member. Also, there is provided a
construction comprising a heat-discharging member arranged between
a plurality of or a single said elements that are the subject of
cooling and the keyboard and thermally contacting the elements that
are the subject of cooling and the keyboard.
[0015] Also, a construction may be provided in which an electronic
equipment comprises a first casing on which are mounted a keyboard
and a wiring board, and a second casing accommodating a display
device and rotatably mounted on said first casing by means of a
hinge, and further comprising a thermally conductive member
thermally connected with one or more elements that are the subject
of cooling arranged within the first casing and the surface of said
first casing, and connection means for thermally connecting the
first casing and second casing.
[0016] Further, the connection means may comprise a thermally
conductive member connected by contacting the first
heat-discharging member and the second heat-discharging member and
further comprise a thermally conductive member comprising one or
other of a thermally conductive member connected to the first
heat-discharging member and a thermally conductive member connected
to the second heat-discharging member and connected in contact with
these thermally conductive members or heat-discharging member.
[0017] Furthermore the size of the region of contact of the means
for contact may be adjustable.
[0018] The first heat-discharging member receives the heat of a
plurality of heat-emitting elements on the wiring board and part of
this is discharged from the surface of the first casing through a
heat-discharging path provided by thermal connection between the
first heat-discharging member and the surface of the casing to the
atmosphere. The rest of the heat is thermally conducted to the
second heat-discharging member through the connection of the first
heat-discharging member and second heat-discharging member and is
discharged to the atmosphere from the surface of the second casing.
At this time, the first heat-discharging member receives the heat
of the plurality of elements concurrently, so the heat of the
plurality of elements that are thermally connected to the first
heat-discharging member is discharged from the surface of the first
casing and the surface of the second casing irrespective of their
layout on the wiring board. A layout of the elements such as to
achieve high performance of the system can therefore be achieved
without lowering the cooling performance of the heat-emitting
elements on the wiring board and large-scale alterations to the
cooling structure are not necessary even if the heat-emitting
elements and/or wiring board are altered due to alteration of the
specification of the system.
[0019] Also, the heat generated from heat-emitting elements and/or
device within the first casing is discharged to the outside from
the first heat-discharging member by being transmitted to the first
casing or the keyboard. Concurrently, it is discharged to the
outside from the second casing, which is thermally connected to
this first heat-discharging member. That is, since the heat
generated in the interior of the casing is distributed to all the
surfaces before being discharged to the outside, the casing where
it is touched by persons is appropriately cooled at the same time
as cooling of the elements, without either local rise in
temperature of the surface of the casing or rise in temperature to
the point of causing discomfort to the user.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective cross-sectional view of an
electronic equipment according to an embodiment of the present
invention;
[0021] FIG. 2 is a rear perspective view of the electronic
equipment shown in FIG. 1;
[0022] FIG. 3 is a transverse cross-sectional view taken along the
line III-III of FIG. 1;
[0023] FIG. 4 is a diagram of the thermal resistance circuit of the
electronic equipment shown in FIG. 1;
[0024] FIG. 5 is a cross-sectional perspective view of another
embodiment of an electronic equipment according to the present
invention;
[0025] FIG. 6 is a cross-sectional perspective view of connection
means of a heat-discharging member in the electronic equipment
shown in FIG. 5;
[0026] FIG. 7 is a perspective cross-sectional view of connection
means of another heat-discharging member in an electronic equipment
according to the present invention;
[0027] FIG. 8 is a perspective cross-sectional view of connection
means of yet another heat-discharging member of an electronic
equipment according to the present invention;
[0028] FIG. 9 is a perspective view of connection means of another
heat-discharging member of an electronic equipment according to the
present invention;
[0029] FIG. 10 is a perspective view of connection means of yet
another heat-discharging member of an electronic equipment
according to the present invention;
[0030] FIG. 11 is a cross-sectional perspective view of connection
means of another heat-discharging member of an electronic equipment
according to the present invention; and
[0031] FIG. 12 is a perspective cross-sectional view of connection
means of yet another heat-discharging member of an electronic
equipment according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Embodiments of the present invention are described below
with reference to the drawings.
[0033] A first embodiment of the present invention is illustrated
in FIGS. 1 to 3 and a thermal resistance circuit diagram of this
embodiment is illustrated in FIG. 4. FIG. 1 is an internal
perspective view of a thin electronic equipment typified by a
portable personal computer. FIG. 2 is a rear perspective view of
the embodiment of an electronic equipment shown in FIG. 1; FIG. 3
is a transverse cross-sectional view showing the interior of the
embodiment of an electronic equipment shown in FIG. 1; and FIG. 4
is a schematic diagram showing a thermal resistance circuit of the
electronic equipment shown in FIG. 1.
[0034] The electronic equipment of this embodiment comprises a
sub-wiring board 2 on which are mounted a plurality of elements
including an element 1 that emits a particularly large amount of
heat, such as a CPU (Central Processing Unit) (hereinbelow referred
to as a CPU), a main circuit board 3 on which are mounted a
sub-wiring board 2 and a plurality of elements, a keyboard 4, a
first casing 6 accommodating a storage device 5 etc., and a second
casing 8 accommodating a display device 7. First casing 6 and
second casing 8 are mounted in mutually rotatable manner by means
of hinges 9 at the two respective edges of the casings (only one
edge shown in FIG. 1) 91 and 92. Above CPU 1 there is arranged a
first heat-discharging member 10 thermally connected to CPU 1, and
within second casing 8, a second heat-discharging member 11 is
arranged between display device 7 and the casing wall of second
casing 8.
[0035] First heat-discharging element 10 is a sheet-shaped member
of high thermal conductivity such as aluminium or copper, and has a
cylindrically-shaped section 12 at its end. The
cylindrically-shaped section 12 is formed by the method of
metallically joining a cylindrical member to a sheet-shaped member,
the method of rounding the end of a sheet-shaped member into a
cylindrical shape, a die-cast forming method etc. The second
heat-discharging member 11 is also a sheet-shaped member of high
thermal conductivity such as aluminium or copper, and has a
cylindrical pillar 13 at its end. The cylindrical pillar 13 is
formed by a method such as metallically joining a cylindrical
member to a sheet-shaped member, a method of die-cast forming or
the like. The first heat-discharging member 10 and second
heat-discharging member 11 are connected by fitting cylindrical
section 12 and cylindrical pillar 13 together, cylindrical pillar
13 reaching the end (in FIG. 1 the left end) of cylindrical section
12 of first heat-discharging member 10. The cylindrical pillar 13
is mounted coaxially with the rotating shaft of hinge 9. The
junction of the cylindrical section 12 and the cylindrical pillar
13 is accommodated in first casing 6 and the junction of second
heat-discharging member 11 and cylindrical pillar 13 is
accommodated in second casing 8.
[0036] This structure is also shown in FIG. 2 by a rear perspective
view in the case in which the display section is closed. Since the
joint of second heat-discharging member 11 with cylindrical pillar
13 and cylindrically-shaped section 12 provided on first
heat-discharging member 10 are fitted together at different
locations on cylindrical pillar 13, irrespective of the angle of
first casing 6 and second casing 8, a casing can be formed without
first and second heat-discharging members (13 and 12) that reach
high temperature (about 70.degree. C.) due to the heat of the CPU
being exposed to the outside. Also, the external appearance is not
spoilt.
[0037] Furthermore, although not shown in FIG. 1, in the hinge at
the other end (left end in FIG. 1), a signal lead electrically
connecting display device 7 and main circuit board 3 is passed
through from first casing 6 to second casing 8.
[0038] Next, the heat-discharging structure of this embodiment will
be further described using FIG. 3.
[0039] FIG. 3 is a transverse cross-sectional view taken along the
line III-III of FIG. 1 showing the interior of this embodiment. A
heat-discharging sheet 14 constituted of heat-discharging member is
provided at the bottom surface of first casing 6. The amount of
heat discharged and the amount of heat conducted by
heat-discharging sheet 14 depend greatly on its area, so, if
necessary, it is of practically the same area as the bottom surface
of the casing and is arranged as far as the rear face of the
casing. In particular, by making the area large, the degrees of
freedom of layout of elements on the circuit board can be
increased. Furthermore, if the casing 6 is made of metal such as Mg
metal, a wall surface itself of the casing may be commonly used as
provides a function of the heat-discharging plate 14. CPU 1 is
installed on sub-wiring board 2 and an expansion metal sheet 16 is
mounted on the other side of a flexible heat-conducting member
(consisting of for example a filler such as aluminium oxide mixed
with Si rubber). Sub-wiring board 2 is mounted on main circuit
board 3 by means of a connector 17. Expansion metal sheet 16 is
then thermally connected by contacting heat-discharging block 18
which is arranged on heat-discharging sheet 14, by means of
flexible heat-conducting member 19, passing through main circuit
board 3. Heat-discharging member 10 is arranged on the rear face of
sub-circuit board 2 on which is mounted CPU 1, directly below
keyboard 4, with a flexible thermally conducting member 20 arranged
therebetween. Heat-discharging member 10 and the base section of
the keyboard (it is desirable that this should be of metal of high
thermal conductivity) are in contact or thermally connected through
a flexible heat conducting member (not shown) or the like.
Heat-discharging member 10 could be the base section itself of the
keyboard.
[0040] It is desirable that heat-discharging member 10 should be of
an area as wide as possible from the heat-emitting elements in
order that this can be arranged so as to cover a plurality of
heat-emitting elements such as heat-emitting elements 2-a, 2-b on
the sub-circuit board 2 and heat-emitting element 3-a on the main
circuit board 3. Furthermore, heat-discharging member 10 has a
cylindrical section 12 at its end. Furthermore, also within second
casing 8 that accommodates the display device 7, the second
heat-discharging member 11 having the cylindrical pillar 13 at its
end is arranged at the back surface within the casing. A gap (air
insulation layer) is formed between the heat-discharging member 11
and the display device 7 so that the heat-discharging member 11
does not heat up the display device 7. Furthermore, if the casing 8
is made of metal such as a Mg alloy, the wall surface itself of the
casing may be commonly used as provides a function of the second
heat-discharging member 11. The cylindrical section 12 of the
heat-discharging member 10 and the cylindrical pillar 13 of
heat-discharging member 11 are connected by insertion-fitting, so
that the second casing 8 is rotatable with respect to first casing
6 about the cylindrical pillar 13 as centre (on the same straight
line as the hinge shaft that connects the first casing 6 and the
second casing 8). The heat discharging ability of the connecting
section (cylindrical section 12) of heat-discharging member 10 and
heat-discharging member 11 can of course be improved by making it
integral with the heat-discharging members, but, in order to
improve ease of assembly, it is demountably mounted by a method
such as a stop screw.
[0041] The heat-discharging effect of expansion metal sheet 16,
heat-discharging sheet 14, and heat-discharging members 10 and 11
is improved by dispersion of heat in the direction of the surface.
The heat that is generated by CPU 1 is distributed into heat that
is discharged to the atmosphere through flexible thermally
conducting member 15, expansion metal sheet 16, flexible thermally
conducting member 19, heat-discharging block 18, and
heat-discharging sheet 14 from the bottom surface of casing 6, and
the heat that is discharged through sub-circuit board 2, flexible
thermally conducting member 20, and heat-discharging member 10.
Furthermore, heat-discharging member 10 is thermally connected with
a plurality of heat-emitting elements such as heat-emitting
elements 2-a, 2-b on sub-circuit board 2 and heat-emitting element
3-a on main circuit board 3. Heat from the plurality of
heat-emitting elements such as heat-emitting elements 2-a, 2-b on
sub-circuit board 2 and heat-emitting element 3-a of main circuit
board 3 is transmitted to heat-discharging member 10 directly by
thermal conduction in the air or by radiation, or indirectly by
thermal conduction into the circuit board. Of the heat that is
transmitted to heat-discharging member 10, some is discharged to
the atmosphere through keyboard 4 while the rest is thermally
conducted to heat-discharging member 11 from the insertion-fitting
sections (12 and 13) of heat-discharging member 10 and
heat-discharging member 11 and is discharged to the atmosphere
through the wall of the second casing 8. It should be noted that,
since heat-discharging member 10 is arranged covering the plurality
of heat-emitting elements on sub-circuit board 2 and main circuit
board 3, the heat of the elements on the respective circuit boards
is transmitted to heat-discharging member 10 irrespective of the
positions in which the elements are arranged within sub-circuit
board 2 or the position in which sub-circuit board 2 is mounted on
main circuit board 3.
[0042] FIG. 4 is a diagram showing the heat resistance circuit in
this embodiment and is given in explanation of the benefits of this
embodiment. From the CPU to the atmosphere, there are a large
number of heat paths in complex relationship, but, indicating the
portions whose mutual effect is greatest, these may be divided into
a first heat-discharging path whereby heat is discharged from the
CPU to the atmosphere through the heat-discharging member at the
bottom surface and the bottom surface of the first casing (thermal
resistance: R1), and a second heat-discharging path whereby heat is
discharged from the CPU through the heat-discharging member on the
keyboard side constituting a first heat-discharging member (thermal
resistance: R2). It should be noted that, as mentioned above, these
heat-discharging members within the first casing also receive heat
from heat-emitting elements other than the CPU, but, for the sake
of simplicity, the description will concentrate on emission of heat
by the CPU.
[0043] The first path whereby heat is discharged from the CPU
through the heat-discharging member on the keyboard side may be
further divided into the second path whereby heat is discharged to
the atmosphere through the keyboard surface from the first
heat-discharging member (thermal resistance: R3) and a third
heat-discharging path (thermal resistance: R5) whereby heat is
discharged to the atmosphere through the rear face of the second
casing accommodating the display device from the second
heat-discharging member through the insertion-fitting section
(thermal resistance: R4) of the first heat-discharging member and
second heat-discharging member. Typical approximate magnitudes of
these respective thermal resistances at the current technical level
are R1=16.degree. C./W, R2=6.degree. C./W, R3=8.degree. C./W and
R5=10.degree. C./W. The thermal resistance R4 of the
insertion-fitting section of the first heat-discharging member and
second heat-discharging member is R4=about 3.7.degree. C./W when
for example the respective materials are aluminium, the internal
and external diameter of the cylindrically-shaped section are
respectively 4 mm and 6 mm, the gap is 10 .mu.m, and the insertion
length is 15 mm. Consequently, the total thermal resistance R from
the CPU to the atmosphere is
R=1/(1/R1+1/(R2+R3.multidot.(R4+R5)/(R3+R4+R5)))=about 6.5.degree.
C./W. The amount of heat generated by a typical current CPU is
about 8 W and the amount of heat generated by future CPUs will tend
to increase, so finding the approximate amounts of heat discharged
by using these values, the amount of heat discharged to the
atmosphere from the bottom surface of the casing is 3.3 W, the
amount of heat discharged to the atmosphere from the keyboard
surface is 3.0 W, and the amount of heat discharged to the
atmosphere from the rear face of the second casing is 1.7 W. Also,
if the atmosphere temperature is 35.degree. C., the CPU temperature
becomes 87.degree. C. In contrast, if the present invention is not
employed i.e. if the heat-discharging path enclosed by the broken
lines in FIG. 4 is absent, the total resistance R is R=1/(1/R1
+1/(R2+R3))=7.5.degree. C./W. In this case the amount of heat
discharged to the atmosphere from the bottom surface of the casing
is 3.7 W and the amount of heat discharged to the atmosphere from
the upper surface of the keyboard is 4.3 W, resulting in a CPU
temperature of 95.degree. C. Consequently, in the case of this
embodiment of the present invention, compared with the case where
the above construction of the present invention is not employed,
the CPU temperature can be reduced by 13% (in terms of the
temperature difference with the atmosphere) and the amount of heat
discharged from the keyboard surface can be reduced by 30%.
[0044] Now let us consider the temperature of the keyboard surface
that is touched by the user or operator. In this embodiment of the
invention, the amount of heat discharged from the keyboard surface
is reduced from 4.3 W to 3.0 W. Consequently, taking into account
the thermal resistance (current typical value: about 3.degree.
C./W) from the keyboard surface to the atmosphere, the rise in
temperature of the keyboard surface from the atmosphere temperature
is reduced from 12.9.degree. C. to 9.0.degree. C. i.e. the
temperature difference with the atmosphere can be kept below the
10.degree. C. which has been experimentally found to cause
discomfort. That is, for a CPU whose heat generation rate is more
than 8 W, the thermal resistances of the various parts can be
designed such that the amount of heat discharged from the keyboard
surface is kept below 3.3 W by transferring an amount of heat of
more than 1.7 W to the second casing in order to restrain the rise
in temperature of the keyboard surface from the atmosphere
temperature to under 10.degree. C.
[0045] The resistance R4 of the insertion-fitting section of the
first heat-discharging member and second heat-discharging member
depends on the magnitude of the gap of the insertion-fitting of the
cylindrically-shaped section and cylindrical pillar, and on the
insertion length. As an example, if the respective materials are
aluminium and the internal diameter and external diameter of the
cylindrically-shaped sections are respectively 4 mm and 6 mm, the
thermal resistance R4 may be found as follows depending on the
magnitude of the insertion-fitting gap and the insertion length.
Specifically, R4 (.degree. C./W) when the magnitude of the gap is
changed to 10, 20, and 30 (.mu.m) respectively is 3.7, 5.9, and 9.6
(where the insertion length is fixed at 15 mm). On the other hand,
R4 (.degree. C./W) in the case where the insertion length is
altered to 10, 15, and 20 mm respectively is 4.6, 3.7, and 3.6 (if
the gap is fixed at 15 .mu.m). If metal is employed, a gap of about
10.about.30 .mu.m can very easily be obtained with ordinary
mechanical processing precision. In the above, the case was
described in which heat transfer between the cylindrical pillar
member and cylindrical member was achieved through an air layer;
however, thermal resistance can be greatly reduced by interposing a
thermally conductive grease or oil. For example, if the gap is 10
.mu.m and the insertion length is 15 mm, if a thermally conductive
grease is interposed, R4=1.2.degree. C./W i.e. it can be reduced by
a factor of about 1/3.
[0046] With the construction as described above, the heat generated
in the interior of the first casing is discharged by being
transferred from a heat-discharging member at the bottom surface of
the first casing or a heat-discharging member on the back surface
of the keyboard through means for connection to a heat-discharging
member of the second casing, so the amount of heat that is
transmitted to the bottom surface of the first casing or portions,
keyboard and so on that are actually touched by the user is
reduced, thereby enabling the temperature of these to be kept below
a temperature that is uncomfortable for the user and so enabling
comfort during use to be improved.
[0047] Also, since the first heat-discharging member of the first
casing has an area that covers a plurality of elements and extends
in an area for example about the same as that of the main circuit
board or the same as that of the bottom surface of the first
casing, the heat of a plurality of elements that are thermally
connected to the first heat-discharging member is conducted to the
second heat-discharging member in a reliable manner from the means
for connection regardless of the layout of the elements.
Specifically, restrictions from the point of view of cooling and/or
heat discharging on the layout of elements within the interior of
the first casing and hence on the layout of equipment including
circuit boards can be greatly reduced, enabling a layout of the
elements and/or equipment to be adopted that is most suited to
achieving high performance of system operation and that can cope
with alterations of wiring for the heat-emitting elements and/or
circuit boards resulting from system specification alterations or
on maintenance, without greatly altering the cooling construction:
construction costs can therefore be reduced. Furthermore, since the
heat from heat-emitting elements on the sub-circuit board is made
to pass through the main circuit board, whence it is conducted to
the first heat-discharging member, the degrees of freedom not only
in the planar layout on the circuit board but also in the vertical
direction of the circuit board are increased i.e. the degrees of
freedom of the elements and/or equipment are further increased
since the heat of the heat-emitting elements can be conducted to
both the keyboard and the bottom surface: thus an arrangement can
be achieved that is beneficial in terms of manufacturing costs and
achieving higher performance.
[0048] Also, the heat generated from the heat-emitting elements
and/or equipment within the first casing is conducted from the
first heat-discharging member (on the bottom surface side of the
casing or on the keyboard side of the elements) to the first casing
or to the keyboard, whence it is discharged to the outside. At the
same time, it is discharged from the second casing that is
thermally connected to the first heat-discharging member to the
outside. That is, since the heat that is generated within the
casing is discharged to the outside from the upper surfaces of the
casing after being dispersed within the casing, there is no
possibility of local heating of the upper surface of the casing or
of heating to such an extent as to cause discomfort to the user;
thus, not only can the elements be cooled but also the casing where
it is touched by human beings can be appropriately cooled.
[0049] Also, by making it possible to adjust the area of contact of
both heat-discharging members at the junction of the first and
second heat-discharging members i.e. the area of thermal
conduction, the amount of heat discharged to the outside from the
first and second heat-discharging members can be adjusted to cope
with performance upgrades and/or increases in the amount of heat
generated by the heat-emitting elements without needing to greatly
alter the cooling structure: thus the distribution whereby the
amount of heat emitted from the interior of the casing is
distributed to the entire casing can be adjusted in a simple
manner.
[0050] FIG. 7 is a perspective view showing a third embodiment of
an electronic equipment according to the present invention.
[0051] According to the heat circuit diagram of the first
embodiment described in FIG. 4, the reduction of the thermal
resistance (R4+R5) from the contact member of the first
heat-discharging member and second heat-discharging member through
the second heat-discharging member as far as the wall surface of
the second casing is beneficial in reducing the temperature of the
CPU and in reducing the amount of heat discharged from the
keyboard. Specifically, in the above embodiment, heat is conducted
to the second heat-discharging member side from the connecting
portion of the connecting members of the first and second
heat-discharging members. Consequently, by making the connection
area at this connecting portion as large as possible, R4 is reduced
and, as in the first embodiment, when the connecting member does
not directly support the first and second casings in the case where
they are connected each other a construction with better heat
conduction efficiency can be obtained, so for example an
arrangement in which a tube structure is adopted is shown in FIG.
7. FIG. 7 is a perspective view showing a first embodiment of an
electronic equipment according to the present invention.
[0052] In the embodiment shown in FIG. 7, there is illustrated only
the first heat-discharging member 10 that is accommodated in the
first casing and is thermally connected to the CPU and the second
heat-discharging member 11 that is accommodated in the second
casing and that is arranged between the display device and the wall
surface of the casing. First heat-discharging member 10 that is
thermally connected to the CPU and second heat-discharging member
11 are respectively provided with cylindrically-shaped sections 12
and 13 at their ends. Cylindrically-shaped sections 12 and 13 are
insertion-fitted on to a heat pipe 22 bent in L shape.
Cylindrically-shaped section 12 of first heat-discharging member 10
and heat pipe 22 are insertion-fitted with the provision of a gap
(about 10.about.20 .mu.m) so that rotation is possible about heat
pipe 22. In installation into the casing, the axis of rotation of
the hinge and this heat pipe rotating shaft 22-a are arranged on
the same straight line. Cylindrically-shaped section 13 of second
heat-discharging member 11 and heat pipe 22 are fixed by swaging to
round the entire end of second heat-discharging member 11.
[0053] In this embodiment, the heat of the CPU that is thermally
conducted to heat pipe rotation shaft 22-a through first
heat-discharging member 10 is transmitted to the entire end of
second heat-discharging member 11 by means of the heat pipe, so
dispersion of heat to the entire second heat-discharging member 11
can be performed efficiently. The thermal resistance from the first
heat-discharging member through the second heat-discharging member
to the wall face of the second casing can therefore be reduced.
[0054] In the above embodiments, for convenience in description,
the case was described in which the heat-discharging member on the
keyboard side constituted first heat-discharging member 10;
however, there is no difference with respect to the technical
concept of the invention disclosed in this specification if
heat-discharging member 14 on the bottom surface side of the first
casing is taken as being the first heat-discharging member.
[0055] Normally the electrical connection between display device 7
and main circuit board 3 is implemented by a large number of signal
lines. Consequently, depending on the type of machine, signal lines
21 are passed from the first casing 6 to the second casing 8 at
both edges of the casings where hinge 9 is provided. In the first
embodiment described above, the arrangement of the construction
whereby heat is transferred from first casing 6 to second casing 8
at a single hinge section and the wiring for the signal lines
cannot be performed concurrently. It would therefore be desirable
for a construction to be adopted whereby signal wiring and thermal
conduction are performed at the same connecting portion by
simultaneously implementing the construction for conducting heat
from first casing 6 to second casing 8 and the wiring of signal
lines 21 at the hinge section. Such an embodiment is shown in FIG.
5 and FIG. 6.
[0056] FIG. 5 and FIG. 6 which are next illustrated are perspective
sectional views showing a second embodiment of the present
invention relating to an electronic equipment.
[0057] Just as in the case of the example shown in FIG. 1, first
heat-discharging member 10 that is thermally connected with the CPU
has at its end a cylindrically-shaped section 12.
Cylindrically-shaped section 12 is insertion-fitted on to the shaft
93 of hinge 9 with a suitable gap, for example a gap of about
10.about.20 .mu.m, such that it can rotate about shaft 93. Within
second casing 8, second heat-discharging member 11 is arranged
between display device 7 and the casing wall of second casing 8;
second heat-discharging member 11 and member 93-a (preferably
integrated with hinge shaft 93) are fixed for by example screws 94,
95 with second casing 8. Of the heat generated by the CPU, some is
discharged to the atmosphere from the upper surface of the keyboard
(not shown) which is arranged above first heat-discharging member
10 while the rest of the heat is thermally conducted to second
heat-discharging member 11 through the shaft of hinge 9 and is
discharged to the atmosphere from the casing wall of second casing
8.
[0058] In the embodiment shown in FIG. 5, hinge 9 itself was
utilized as a thermally conducting member; however, it would be
possible to simplify the construction and so lower costs by
dispensing with first heat-discharging member 10 mounted on the
hinge shaft, albeit with some loss of heat-discharging performance.
Such an embodiment is shown in FIG. 6. In this embodiment, hinge 9
is formed of material of high thermal conductivity and high
mechanical strength and hinge legs 91-a, 91-b are fixed to first
casing 6 and a heat-discharging sheet 14 that is provided at the
bottom of first casing 6. The internal construction of second
casing 8 is the same as in the case of FIG. 5. Flanges 9-b, 9-d
integrally formed with shaft 9-a of hinge 9 create reinforcement by
being pressed against member 9-c that is connected to second casing
8. Although not shown in the drawings, the contact area with shaft
9-a is increased by means of a member that presses member 9-c by
gripping this with flanges 9-b, 9-d and further by the fact that
the width of section 9-c increases in the direction of shaft 9-a;
the thermal resistance of shaft 9-c and section 9-a is thereby
decreased. Some of the heat generated by the CPU is thermally
conducted from a heat-discharging sheet through the legs 91-a, 91-b
of the hinge and hinge shaft 9-a to the second heat-discharging
member 11 arranged within second casing 8. Consequently, with this
embodiment, some of the heat of the CPU can be discharged to the
atmosphere from the second casing simply by means of hinge 9. The
heat-discharging performance obtained by this embodiment can of
course be increased by combining it with the other embodiments.
[0059] FIG. 8 to FIG. 10 which describe another example relating to
the means of connection of the first heat-discharging member and
second heat-discharging member in the embodiment shown in FIG. 1
and FIG. 5. FIG. 8 to FIG. 10 are views showing an insertion
section of a heat-discharging member in an embodiment of an
electronic equipment according to the present invention.
[0060] The embodiments shown in FIG. 1 and FIG. 5 illustrated the
case where the two insertion sections consisted of an assembly of a
cylindrical pillar face and cylindrical face; however, in the case
of the means for connection shown in FIG. 8, an embodiment of a
structure is illustrated whereby the thermal resistance at the
insertion gap of these two is further reduced. The surface area is
increased by screw-thread processing 31, 32 on the cylindrical
pillar shaft 13 formed on second heat-discharging member 11 and
cylindrically-shaped section 12 formed on first heat-discharging
member 10. In the case of the casing that accommodates the display
device (where the second heat-discharging member 12 is arranged),
if this is assumed to be tipped over by 180.degree. at a maximum
with respect to the main casing on which is mounted the CPU etc.
(in which is arranged first heat-discharging member 10), the
insertion sections of the first heat-discharging member and second
heat-discharging member slide in the axial direction through 1/2
pitch of the screw at the maximum (in the case of a JIS mesh screw,
0.25 mm for a shaft diameter of 5 mm). Consequently, a gap of at
least 1/2 pitch is provided between cylindrically-shaped section 12
and cylindrical pillar shaft 13, or alternatively, a structure is
adopted whereby displacement between the first heat-discharging
member and second heat-discharging member can be absorbed (for
example, a structure in which a heat-emitting section is connected
with first heat-discharging member 10 using a flexible thermally
conducting member 20 shown in FIG. 3).
[0061] FIG. 12 shows an embodiment in which an insertion structure
of the screw-threaded section is adopted in the case of the second
heat-discharging member 11 just as in the case of the first
heat-discharging member 10. In the construction shown in FIG. 12, a
female screw-thread is also provided not just on the inside of
cylindrical member 12 but also on the inside of cylindrical member
37 on the side of the second heat-discharging member.
Heat-discharging members 10, 11 are coupled to the two cylindrical
members 12, 37 by insertion of male screw-threaded member 36. Male
screw-threaded member 36 is provided with a notch in its end face,
so that the area of contact i.e. the area of thermal conduction can
be adjusted by altering the insertion length 1 of first
heat-discharging member 10 and second heat-discharging member 11 by
using a tool, utilizing this notch, male screw-threaded member 36
being freely movable in its axial direction. In this case,
screw-threading can be formed on the entire shaft and male
screw-threaded member 36 can be freely slid with respect to first
and second heat-discharging members 10, 11, so control of the area
of contact of the heat-discharging members and the central shaft
i.e. control of the thermal resistance becomes possible and such
adjustment can be performed easily without requiring special
equipment. Consequently, even in the case of maintenance or when
the product specification is altered, there is no need for large
alterations of the cooling structure in order to make the
temperature of keyboard 4 and/or the bottom surface of first casing
6 below a desired temperature, so it is possible to cope with
increases in the amount of heat generated and/or performance
upgrades; since alterations in wiring etc. relating to the circuit
boards and/or heat-emitting elements occurring during maintenance
and/or system specification alterations can be coped with without
large-scale alterations of the cooling structure, manufacturing
costs can be reduced. Furthermore, since the connection area is
expanded at the insertion sections of the first heat-discharging
member and second heat-discharging member, thermal connection can
be achieved so as to reduce thermal resistance of the first
heat-discharging member and second heat-discharging member.
[0062] A further embodiment of the insertion section is shown in
FIG. 9. This embodiment is an example in which the
cylindrical-shaped section and cylindrical pillar shaft provided on
the first and second heat-discharging members are formed by a
simple and convenient processing method. In this embodiment, a
member 101 that is subjected to rounding bending processing is
connected at the end of second heat-discharging member 11.
Furthermore, a member 100 that is subjected to rounding bending
processing is also connected to the end of first heat-discharging
member 10 and the two are connected by insertion of a cylindrical
pillar shaped member 13 into both of these. In this case, a gap 33
is provided between the rounded bent section of first
heat-discharging member 10 and cylindrical pillar shaft 13 and
first and second heat-discharging members 10 and 11 are connected
so as to be mutually rotatable. With this cylindrical pillar member
13, just as in the case of the first embodiment, by adjusting the
insertion length T by which it is inserted, the contact area
between the first heat-discharging member and second
heat-discharging member can be altered, thereby enabling the
thermal resistance between these to be altered. In order to
facilitate this adjustment, cylindrical pillar shaped member 13 is
provided with a scale 13-a to provide a standard on its surface and
so can easily be adjusted to the desired rate of thermal conduction
or thermal resistance. Also, in this example, lowering of costs can
be achieved since the insertion sections are formed merely by a
sheet member and rounded rod member and by a simple method.
[0063] It is desirable that the thickness of the sheet of the first
and second heat-discharging members should be as large as possible
from the point of view of heat-discharging performance. However, in
the case of the means for connection shown in FIG. 9, processing of
the sheet end becomes more difficult as sheet thickness is
increased and processing accuracy also is more difficult to
achieve. The means for connection shown in FIG. 10 is an example
which is improved in this respect. In this embodiment, sheet
members 34, 35 of thickness 1/2 of the necessary thickness from the
point of view of heat-discharging performance are rounded and bent
into cylindrical shape from the centre about axial shaft 13 so as
to grip first heat-discharging member 10 and second
heat-discharging member 11 at their ends. In this embodiment, this
construction is employed for both the first and second
heat-discharging members but it would be possible to adopt another
construction, for example that shown in FIG. 9, for one or other of
the heat-discharging members. With this embodiment, processing is
facilitated since the sheet thickness can be halved for the same
heat-discharging performance and bending can be performed at the
centre of the sheet; also, the precision of the gap between
cylindrically-shaped section 34 and axial shaft 13 can be
increased. Consequently, the gap can be reduced i.e. the thermal
resistance at the gap can be decreased.
[0064] FIG. 11 shows a further embodiment of the connection
sections of the first heat-discharging member and second
heat-discharging member. In this example, first heat-discharging
member 10 and second heat-discharging member 11 are connected by a
thin sheet member 37 formed of material of high thermal
conductivity (for example, copper sheet or phosphor bronze sheet of
thickness 50 .mu.m-0.1 mm). In FIG. 11, thin sheet member 37 and
first and second heat-discharging members 10, 11 are connected by a
method such as fixing using for example a screw 38. When connection
of first heat-discharging member 10 and second heat-discharging
member 11 is performed using thin sheet member 37, thanks to the
bending of thin sheet member 37, a flexible and thermal connection
that follows the movement between first casing 6 and second casing
8 is achieved. Also, a plurality of thin sheets may be stacked in
order to decrease the thermal resistance of the connecting section.
In this case, in order to maintain flexibility between the
heat-discharging members, the thin sheets are mutually joined only
at the connecting section with the heat-discharging member. As
shown in FIG. 10, the thin sheet member 37 is connected to the
first heat-discharging member 10 in the first casing 1 by pressing
it thereon using a plurality of screws; the thermal resistance of
the connecting section of thin sheet member 37 which constitutes
the connecting member of the first and second heat-discharging
members may be adjusted by altering the number of these connecting
screws. Regarding the thermal resistance at the contacting section
of the two members, increasing the contact pressure, even if the
apparent contact area is the same, increases the actual contact
area and so enables the thermal resistance to be reduced.
[0065] Furthermore, as shown in FIG. 11, by bending the connecting
section of thin sheet member 37 with first heat-discharging member
10, fixing may be effected by means, such as a screw 38 in this
bent section, that press thin sheet member 37 onto the
heat-discharging member 10. In this way, it is possible to adjust
the contact area of the thin sheet member 37 and the
heat-discharging member 10 by fewer means for pressing, enabling
the thermal resistance to be more easily adjusted.
[0066] Also, by making the area of connection of the two
heat-discharging members at the connection section of the first and
second heat-discharging members i.e. the area of thermal conduction
adjustable, the rate of heat discharging to the outside from the
first and second heat-discharging members can be adjusted to cope
with increases in the rate of heat generation by the heat-emitting
elements and/or performance upgrades without needing to make major
alterations to the cooling structure, and the distribution whereby
the amount of heat generated from the interior of the casing is
dispersed to the entire casing can be adjusted in a simple manner
so that the casing also can be appropriately cooled concurrently
with cooling of the elements.
[0067] With this embodiment, flexible thermal connecting sections
are formed by an uncomplicated construction so lower costs can be
achieved. Also, although in the example described above, means for
adjusting thermal resistance were provided on the side of the means
for connecting the first and second heat-discharging members where
the first heat-discharging member is connected, there is no
restriction to providing it on the side of the first
heat-discharging member and the same benefits could of course be
obtained by providing it on the other side.
[0068] According to the present invention, irrespective of the
layout of heat-emitting elements on the wiring board or the layout
of equipment in the interior of the casing, an electronic equipment
can be provided having a cooling construction suited to a thin
light-weight casing wherein the rise in temperature of the surface
of the casing that accommodates the heat-emitting elements and
keyboard, etc. is restrained and which does not give the operator
an uncomfortable feeling and cooling of the temperature of the
heat-emitting elements is effected to a prescribed temperature.
[0069] Furthermore, an electronic equipment can be provided having
a cooling structure that maintains the casing and keyboard at a
temperature that does not give discomfort to the operator whilst
maintaining the heat-emitting elements below a prescribed
temperature by suitably dispersing to the entire device the amount
of heat generated from heat-emitting elements or equipment within
the casing.
[0070] Furthermore, an electronic equipment can be provided having
a cooling construction wherein the rate of discharging of heat from
the casing can be adjusted to cope with changes in layout of
heat-emitting elements and/or equipment within the casing.
* * * * *