Keyboard assembly including circuit membrane switch array

Details Keyboard assembly including circuit membrane switch array Keyboard assembly including circuit membrane switch array

1999-07-02

2001-07-24

Scott, J. R. (Department: 2832)

Electricity: circuit makers and breakers

Multiple circuit control

Multiple switch

C200S517000, C200S341000

Reexamination Certificate

active

06265677

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the structure of a keyboard. More particularly, it relates to the structure of a keyboard assembly capable of being assembled in an efficient way.
DESCRIPTION OF THE PRIOR ART
FIG. 1
is an exploded perspective view showing the structure of a conventional keyboard assembly
1
. As shown in
FIG. 1
, the keyboard assembly
1
is composed of a keyboard hood
10
, a plurality of key caps
11
, a plurality of dome-shaped elastic components
13
, a circuit membrane
14
, a metal plate
15
and a keyboard base
12
. The keyboard hood
10
is of a rectangular shape and is provided with a first surface
101
and a second surface
102
. Furthermore, the keyboard hood
10
is provided with a plurality of through holes
100
for accommodating the cylindrical end portions
110
of the key caps
11
. The key caps
11
are inserted into the through holes
100
in the direction from the first surface
101
toward the second surface
102
of the keyboard hood
10
. The circuit membrane
14
and the metal plate
15
are affixed on the keyboard hood
10
by a plurality of screws
16
with the dome-shaped elastic components
13
disposed therebetween, and the keyboard hood
10
is connected to the keyboard base
12
by a plurality of screws
17
.
FIG. 2A
is an exploded perspective view showing the structures of the dome-shaped elastic component
13
, the through hole
100
of the keyboard hood
10
, the key cap
11
, the circuit membrane
14
and the metal plate
15
. The openings
103
,
104
of the through hole
100
are formed respectively on the first surface
101
and the second surface
102
of the keyboard hood
10
. A circular rim
105
is formed around the opening
104
of the through hole
100
.
FIG. 2B
is an exploded perspective view showing the state in which the elastic component
13
and the key cap
11
are assembled together with the keyboard hood
10
. As shown in
FIG. 2B
, the end portion
130
of the elastic component
13
is in contact the cylindrical end portion
110
of the key cap
11
.
FIG. 3
is a cross-sectional view showing a wiper being used to feed elastic components into the through holes formed on the keyboard hood. As shown in
FIG. 3
, a wiper
5
is used to urge dome-shaped components
13
to enter the through holes
100
. The wiper
5
is in the form of an elastic blade, which is used to sweep over the top end portion
106
of the circular rim
105
of the through holes
100
.
During operation, the dome-shaped components
13
are scattered on the second surface
102
and incidentally some of them are disposed within the through holes
100
. As shown in
FIG. 3
, the top surface of the upper rim
131
of the elastic component
13
disposed within the through holes
100
is higher than the circular rim
105
formed on the second surface
102
of the keyboard hood
10
by an elevation difference H
+
. Therefore, it stands a chance that the dome-shaped components
13
disposed within the through holes
100
might bound out of the through holes
100
when the wiper
5
urges the upper rims
131
of the dome-shaped components
13
during the sweeping of the wiper
5
over the through holes
100
. If there still exists an empty through hole
100
that is not filled with a dome-shaped component
23
, then the wiper
5
has to sweep once again. Hence, the total process is inefficient.
SUMMARY OF THE INVENTION
Therefore, the object of this invention to provide means for preventing the dome-shaped components from bounding out of the through holes while the wiper sweeps over the through holes.
To achieve the above object, the keyboard assembly of this invention comprises a plurality of key caps, each of which having an end portion; a keyboard hood provided with a plurality of through holes, each through hole having a first opening and a second opening, the end portions of the key caps being inserted into the first opening, and a top rim being formed on the brim of each second opening and a plurality of protrusions being formed on the top rim of each through hole; a plurality of dome-shaped elastic components disposed within the through holes of the keyboard hood so as to allow their bottoms to be urged by the end portions of the key caps, each dome-shaped elastic component having an upper rim and a bottom, the protrusions formed on the top rim of each through hole being higher than the upper rim of the dome-shaped elastic components disposed within the through holes; a circuit membrane disposed in a manner that it contacts with the upper rims of the dome-shaped elastic components; and a keyboard base fastened to the keyboard hood so as to enclose the end portions of the key caps, the dome-shaped elastic components, the circuit membrane, and the plate therebetween.
Furthermore, the protrusions formed on the top rim of each through hole are spaced apart from each other.
Furthermore, the circuit membrane is provided with a plurality of punched holes formed therein, and each punched hole is located at a site corresponding to a protrusion so as to allow the protrusions to penetrate therethrough.
Furthermore, in the above keyboard assembly, a metal plate is additionally disposed between the keyboard base and the circuit membrane, the metal plate being provided with a plurality of punched holes, each of which is located at a site corresponding to a protrusion so as to allow the protrusions to penetrate therethrough.
Furthermore, the keyboard base is provided with a plurality of recesses, each of which is located at a site corresponding to a protrusion so as to allow the protrusions to insert therein.
As the protrusions formed on the top rim of each through hole is higher than the upper rim of the dome-shaped elastic components disposed within the through holes, the dome-shaped components can be received in the through holes without being hit by the wiper sweeping over the through holes.


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