Thin keyboard apparatus

Details Thin keyboard apparatus Thin keyboard apparatus

1999-04-01

2001-05-01

Ramirez, Ramon O. (Department: 3632)

Electricity: circuit makers and breakers

Electric switch details

Actuators

Reexamination Certificate

active

06225586

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a keyboard apparatus used as an apparatus with which to enter characters, etc. and, more particularly, to a thin keyboard apparatus suited for use with a notebook-size computer.
2. Description of the Related Art
FIG. 6
is a sectional view showing a key of a conventional keyboard apparatus
20
as observed sideways. The keyboard
20
is constituted primarily by a key top
1
, supporting members
2
and
3
, a housing member
31
, a membrane switch
4
, a metal plate
5
, and an elastic member
6
.
The key top
1
is provided with a total of four retaining portions
1
a,
1
a,
1
b,
and
1
b
which are located at the four corners of the rear surface of the key top
1
to support the supporting members
2
and
3
.
The supporting members
2
and
3
, which support the key top
1
, are installed so that they intersect with each other, and attached by a shaft
8
provided at the center of side faces thereof so that they may circularly move. The supporting member
3
disposed on the inner side has a round through hole
9
formed at the center thereof as shown in FIG.
5
. The supporting member
2
disposed on the outer side is shaped like “C” as shown in FIG.
5
. The distal ends of the supporting members
2
and
3
, respectively, have columnar protuberances
2
a,
2
a,
3
a,
and
3
a
projecting outward. The protuberances
2
a
are disposed and inserted in the retaining portions
1
b
so that it may slide back and forth, while the protuberances
3
a
are fitted in the retaining portions
1
a
and rotatably supported therein.
The columnar protuberance
2
b
formed on the proximal end of the supporting member
2
is rotatably attached to a retaining portion
32
of the housing member
31
, while the columnar protuberance
3
b
formed on the proximal end of the supporting member
3
is slidably disposed in a recess
33
. In the supporting member
3
, a shaft (not shown) provided between legs
3
c
and
3
c
is locked by a retaining member protruding from the housing member
31
so as to prevent the supporting member
3
from coming off the housing member
31
.
The bottom surface of the housing member
31
is provided with the membrane switch
4
sandwiched between the housing member
31
and the metal plate
5
.
The membrane switch
4
is formed of three layers of film sheets (not shown), two layers, namely, the top and bottom layers, of which being provided with printed electrode patterns formed on the opposing inner surfaces thereof. A film type spacer is inserted between the two sheets of the membrane switch
4
, and the spacer has holes beneath the respective key tops
1
so that the top and bottom electrodes conduct when the key tops are depressed. The membrane switch
4
is further provided with a plurality of apertures running through the three layers to fasten the housing member
31
and the metal plate
5
.
The metal plate
5
formed of a metal constituent such as an aluminum constituent is provided below the bottom surface of the membrane switch
4
.
The metal plate
5
is provided with a plurality of apertures in which a plurality of protuberances of the housing member
31
are inserted, the protuberances being formed at the same positions as the apertures. The protuberances of the housing member
31
that jut out from the underside of the metal plate
5
are partially melted to fasten the housing member
31
and the metal plate
5
.
The elastic member
6
is disposed at the center of the keyboard apparatus
20
. The elastic member
6
passes through the round through hole
9
formed in the housing member
31
and rested on the top surface of the membrane switch
4
without being bonded. The diameter of the through hole formed in the housing member
31
is smaller than the diameter of the bottom end of the elastic member
6
, so that the elastic member
6
does not come off the housing member
31
even if it is not secured by bonding.
The elastic member
6
is formed of a constituent providing an urging force so that it is always urged upward.
The conventional keyboard apparatus
20
, however, is too thick to satisfy the recent demand for achieving further thinner notebook-size computers.
Normally, in a keyboard apparatus used with a notebook-size computer, a thickness X of a key top has been set to 3 mm at the minimum and a travel distance Y of the key top
1
has been set to 3 mm at the minimum, and making the keyboard apparatus further smaller has been restrained in consideration of the feel and ease of use. Hence, a study has been conducted to determine if any of the members from the housing member
31
and below can be omitted because it was impossible to further decrease the thickness X and the travel distance Y.
As a study result, a method has been proposed in which the retaining portions that support the supporting members
2
and
3
are directly supported by the metal plate
5
, thus eliminating the housing member
31
. This, however, has been posing a problem of a higher machining cost because directly forming the retaining members on the metal plate
5
requires that the metal plate
5
be cut and raised to form retaining portions
41
,
41
,
42
, and
42
as shown in FIG.
7
.
In addition, to install the supporting members
2
and
3
, protuberances
3
b
and
3
b
of the supporting member
3
are first hooked to the retaining portions
42
and
42
, then the protuberances
2
b
and
2
b
of the supporting member
2
are inserted in the retaining portions
41
and
41
through openings
41
a
and
41
a.
At this time, the protuberances
2
b
and
2
b
must be fitted in with a strong force because the retaining portions
41
and
41
are shaped like arches. This has been presenting a problem in that the assembly takes more time and is more difficult than in the example of the conventional art shown in FIG.
6
.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a keyboard apparatus that permits a thinner design and is inexpensive and easy to assemble.
To this end, according to the present invention, there is provided a keyboard apparatus provided with: a key top, a supporting member which supports the underside of the key top so that the key top may move up and down, a receiving member which supports the supporting member at a proximal end of the supporting member, an elastic member which urges the key top upward at all times, and a membrane switch provided on the underside of the supporting member; wherein the receiving member is directly secured to a base supporting the membrane switch.
Directly securing the receiving member that supports the supporting member to the base as mentioned above obviates the need of providing the housing member, which exists in the example of the conventional art. This makes it possible to make the keyboard apparatus thinner by eliminating the thickness of the housing member. Moreover, since there is no need to directly cut and raise the metal plate, the apparatus can be manufactured at lower cost.
The base is composed of a metal plate, and the receiving member can be formed by using a resin attached to the metal plate by outsert molding.
In this case, the receiving member can be formed as follows: a through hole is formed in the base beforehand at the location where the receiving member or the retaining member is to be formed, then a resin is poured in through the through hole by clamping the metal plate at its both faces by a metal mold.
The foregoing molding method, which is normally referred to as the outsert method, allows the receiving member or the retaining member to be positively and securely fixed to the base.
Preferably, a recess is formed in the back surface of the base to which the receiving member has been secured so that a part of the receiving member is positioned in the recess so as to prevent it from protruding from the back surface of the base.
Thus, the back surface of the base no longer has the protuberances of the receiving member or the retaining member, making it possible to for

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