Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Reexamination Certificate
2000-03-03
2001-05-29
Donovan, Lincoln (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
C361S688000
Reexamination Certificate
active
06239390
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a personal computer keyboard suitable for a personal computer: especially notebook and portable personal computers, which are both compact.
BACKGROUND PRIOR ART
Since many of heat generating devices such as CPU, a CD-ROM drive and a hard disk are incorporated in a personal computer, there is a need to dissipate generated heat so as to cool the devices in order to ensure normal operations over a long time. For this reason, various kinds of heat dissipating plates have been employed. However, especially, in notebook and portable personal computers, it is unavoidable that the heat generating devices are put inside a small case and a keyboard coexists in the case; many of the heat generating devices are resulted in being crammed in the narrow space, thereby leading to a desire for high heat dissipativity of a heat dissipating plate.
In the mean time, in the keyboard of a personal computer, since key caps with which fingers are put in direct touch are mounted on a base plate with a membrane or a pantograph structure interposed therebetween, and it is required that when a key is pressed down in typing, the base plate do not locally sink due to deformation, therefore a reinforcement plate is disposed on the lower side of the base plate to increase stiffness and cope with such a deformation. Such base and reinforcement plates each have a requirement for having a function as a heat dissipating member to prevent overheating inside the personal computer from occurring by diffusing heat generated from the devices therein in addition to a function as a strength member that supports the key caps and endure shocks of key strokes. Further, needless to say that the light weight and formability of the base and reinforcement plates are necessary.
For such reasons as described above, as material of the base and reinforcement plates, there have widely been adopted an Al—Mg based alloy including aluminum excellent in strength, good in thermal conductivity, and with features of light weight and good forming workability, and Mg in content of about 2.5 wt % especially to increase a mechanical strength.
While such an Al—Mg alloy has a sufficient strength and a good machinability including an excellent cutting property as compared with pure aluminum, the alloy has not been a satisfactory material in terms of heat dissipativity since a thermal conductivity thereof is lower by about 60%. Because of the poor heat dissipativity, the alloy has had a problem in a personal computer using the base and reinforcement plates made of the same since there arise overheating of CPU and other devices, and some of caps with high temperature are locally found in the entire arrangement.
Under such circumstances, the present inventor has proposed an Al—Si—Mg based alloy that seeks a heat dissipativity of pure aluminum, and a strength and machinability of the Al—Mg based alloy. Such a proposed Al—Si—Mg based alloy actually has a good thermal conductivity whereas the alloy is to some extent inferior to the Al—Mg based alloy in regard to a strength and thereby, the problems of overheating of CPU and other devices and caps of high temperature have almost been solved. However, part of the problems have still been left unsolved: Homogeneity in heat dissipation is insufficient and there are still locally found some key caps with high temperature, though, according to distances from the heat generating devices in a personal computer during its operation.
SUMMARY OF THE INVENTION
The present invention has been made in light of such technical circumstances and it is accordingly an object of the present invention to provide a personal computer keyboard with incorporated base and reinforcement plates excellent in heat dissipativity, homogeneous in heat dissipation and having a mechanical strength.
A personal computer keyboard of the present invention, which has been provided for achieving the object, comprises: a base plate
24
on which key caps K1 to K9 are mounted; and a reinforcement plate
25
disposed on the lower side of the base plate
24
, wherein the base plate
24
is constituted of an Al—Mg—Si based alloy plate including 0.2 to 0.8 wt % of Si, 0.3 to 0.9 wt % of Mg, 0.35 wt % or less of Fe and 0.20 wt % or less of Cu with the rest of Al and inevitable impurities and wherein the reinforcement plate
25
is constituted of a heat pipe panel.
Further, a content of Si in the Al—Mg—Si based alloy plate is preferably in the range of from 0.32 to 0.60 wt %.
Still further, a content of Mg in the Al—Mg—Si based alloy plate is preferably in the range of from 0.35 to 0.55 wt %.
Yet further, the base plate is preferably constituted of the Al—Mg—Si based alloy plate whose tensile strength is equal to or higher than 200 N/mm
2
.
Yet further, the reinforcement plate preferably is a heat pipe panel of a structure that is formed by bonding two aluminum flat plates and has an inflated tubular path serving as a path for a working fluid or a heat pipe panel of a structure that has a pipe serving as a path for a working fluid attached on an aluminum flat plate.
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patent: 3591749 (1971-07-01), Comstock
patent: 4991647 (1991-02-01), Kawabe et al.
patent: 5598320 (1997-01-01), Toedtman et al.
patent: 5796581 (1998-08-01), Mok
patent: 5803744 (1998-09-01), Yen
patent: 5946187 (1999-08-01), Cipolla
patent: 5992155 (1999-11-01), Kobayashi et al.
patent: 6031716 (2000-02-01), Cipolla et al.
patent: 6043977 (2000-03-01), Nakajima
patent: 3-8229 (1991-03-01), None
Fukui Koichiro
Tsukuda Ichizo
Ushioda Shunta
Donovan Lincoln
Nguyen Nhung
Showa Aluminum Corporation
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