Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Reexamination Certificate
2000-02-14
2002-09-10
Bradley, P. Austin (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
C200S517000
Reexamination Certificate
active
06448514
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to elastic strips of a keyboard and a method for producing the same.
2. Description of the Related Art
Referring to
FIG. 1
, a conventional keyboard of a notebook includes a plurality of key caps
11
(only one key cap is shown in the figure), a plurality of cap supports
12
(only one cap support is shown in the figure), an elastic sheet
13
, a circuit membrane assembly
14
and a foundation sheet
15
.
The foundation sheet
15
is a metal sheet on which a plurality of seats
151
and hooks
152
are formed by punching and pressing.
The circuit membrane assembly
14
includes three membrane layers, wherein a middle layer is sandwiched by two outer layers. On the outer layers are provided circuits, while on the middle layer are provided holes. By this arrangement, an electric conduction between the two circuits on the outer layers is induced when the outer layers are compressed to contact each other through the holes of the middle layer. Furthermore, a plurality of through holes
141
are provided on the circuit membrane assembly
14
. That is, the through holes
141
penetrate the outer layers and the middle layer of the circuit membrane assembly
14
.
The elastic sheet
13
is made of rubber and is formed by using the Injection Molding Method. The elastic sheet
13
has a sheet-like body
130
, a plurality of elastic domes
131
, connecting portions
133
and through holes
132
, wherein the connecting portions
133
connect the elastic domes
131
and the sheet-like body
130
. Further referring to
FIG. 2
, the elastic dome
131
has a plunger
1311
inside.
The cap support
12
has a first linking bracket
121
and a second linking bracket
122
. The shaft portions
1221
of the second linking bracket
122
are inserted into the holes
1211
of the first linking bracket
121
so that the first linking bracket
121
and the second linking bracket
122
are hinged together. Such a structure is so called “scissors-type support structure”. Furthermore, the first linking bracket
121
has shaft rods
1212
,
1213
and the second linking bracket
122
has shaft rods
1222
on their corners.
Referring to
FIG. 3
, the key cap
11
has hook portions
111
and holding portions
112
,
113
on its bottom surface.
Now, the way of assembling the conventional keyboard is described. The circuit membrane assembly
14
and the elastic sheet
13
are put on the foundation sheet
15
, with the seats
151
and hooks
152
of the foundation sheet
15
sticking out through till the through holes
141
of the circuit membrane assembly
14
and the through holes
132
of the elastic sheet
13
. The key cap
11
is mounted on the foundation sheet
15
via the cap support
12
, wherein the shaft rods
1212
are inserted into the seats
151
so that the first linking bracket
121
is rotatable with respect to the foundation sheet
15
, and the narrow portion
1223
of the second linking bracket
122
is hooked by the hook
152
of the foundation sheet
15
so that the second linking bracket
122
is also rotatable with respect to the foundation sheet
15
. Furthermore, the shaft rods
1213
of the first linking bracket
121
are held by the hook portions
111
, and the shaft rods
1222
of the second linking bracket
122
are held by the holding portions
112
,
113
.
In operation, the user pushes down the key cap
11
so as to compress the elastic dome
131
. Then, the plunger
1311
of the elastic dome
131
pushes against the circuit membrane assembly
14
so that an electric conduction is induced to send out a corresponding signal.
In manufacture, however, the elastic sheet
13
of the conventional keyboard of a notebook has the following flaws: (1) The elastic sheet
13
is made of rubber and formed by the Injection Molding Method. Building the mold for the elastic sheet
13
is expensive. In addition, manufacturers need to build new molds for elastic sheets with new specifications because different kinds of keyboards are provided with different elastic sheets. Therefore, the cost for manufacturing keyboards is high. (2) A mold is built when a keyboard of a new specification is developed. However, if the elastic sheet
13
produced by using the mold has dimensions outside the tolerance, then the mold needs to be rebuilt. Then, the cost of developing the new keyboard is raised, the time for developing the new keyboard is elongated and the mass production of the new keyboards is delayed. It is disadvantageous for commercial competition. (3) The elastic sheet
13
has a plurality of rows of elastic domes
131
formed thereon. The distances between the rows of elastic domes
131
must comply with the distances between the key caps of the keyboard. Therefore, the materials connected between the rows of elastic domes
131
can not be eliminated. In other words, the weight of the elastic sheet
13
and the material cost cannot be reduced. (4) The user pushes down the key caps while typing. Referring to rig.
4
, the stroke for the key cap
11
to contact the elastic sheet
13
is “L”. For a conventional keyboard, however, the stroke generally is not long enough for the user to feel comfortable in operation. Referring to
FIGS. 5A and 5B
, a possible way to increase the stroke is to provide rectangular grooves
134
around the plunger
131
. However, this arrangement reduces the thickness of the elastic sheet under the grooves to “H” so that the resistance of the mold cavity to the flow of the molten material is increased. Then, filling the mold cavity at the positions corresponding to the elastic domes tends to be incomplete.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a means that solves the above-mentioned problems.
In the present invention, an elastic sheet is produced by using a mold, wherein the elastic sheet has a plurality of rows of elastic domes formed thereon. Then, the elastic sheet is cut into a plurality of elastic strips, each of which has only one row of elastic domes. Then, the elastic strips are disposed on keyboards.
To develop keyboards with new specifications, common portions of the new keyboard can use molds with prevailing specifications. Thus, only the molds for the elastic strips of new specifications need to be developed, and the cost for developing a new keyboard is therefore greatly reduced.
It is understood that only the molds for the new specifications need to be developed. If the development fails, the influences are local rather than overall. The engineers can fix the mistakes very soon so as to mass-produce the new keyboards in time. The present invention is advantageous for commercial competition.
In the present invention, the elastic sheets are cut into a plurality of elastic strips. Thus, the distances between the rows of the elastic domes on the elastic sheets do not need to comply with the distances between the key caps of the keyboards. The materials connected between the rows of elastic domes are reduced. And the material cost and the weight of the keyboard are reduced.
In the present invention, recesses are provided on the elastic strips and between the elastic domes to increase the stroke for the key caps to contact the elastic strips. While filling the mold cavity, the arrangement of the recesses does increase the resistance to the flow of molten material. However, the molten material can bypass the arrangement of the recesses so that the whole mold cavity is filled with molten material.
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Bradley P. Austin
Darfon Electronics Corp.
Klaus Lisa N.
Ladas & Parry
LandOfFree
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