Typewriting machines – Key-board or key lever-actuating mechanism – Including mechanism for activating keys
Reexamination Certificate
2001-06-15
2002-12-10
Hirshfeld, Andrew H. (Department: 2854)
Typewriting machines
Key-board or key lever-actuating mechanism
Including mechanism for activating keys
C400S490000, C400S479000, C345S168000, C361S689000, C200S0050EA
Reexamination Certificate
active
06491456
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a key signal-generating device for a keyboard, and more particularly, to a key signal-generating device with a trench to release air.
2. Description of the Prior Art
Please refer to FIG.
1
and FIG.
2
.
FIG. 1
is a schematic diagram of a prior art key signal-generating device
10
.
FIG. 2
is a section view along line
2
—
2
of the prior art key signal-generating device
10
of FIG.
1
. The key signal-generating device
10
generates key signals in a keyboard. The key signal-generating device
10
has a thin film circuit board
18
to generate key signals, and a plurality of rubber domes
20
on a top surface
22
of the thin film circuit board
18
to support a key
16
. The rubber dome
20
is fixed by a glue layer
30
to the top surface
22
of the thin film circuit board
18
.
As shown in
FIG. 2
, the thin film circuit board
18
has a plurality of pressure sensors
32
that correspond to the rubber domes
20
. Each rubber dome
20
has a base
24
, a predetermined space
26
filled with air within the rubber dome
20
, and an orifice
28
in the base
24
to communicate the pressure in the predetermined space
26
with the atmosphere. When a user presses the key
16
, the rubber dome
20
is squeezed by the key
16
to activate the pressure sensor
32
, and a signal is generated correspondingly. The air in the predetermined space
26
is released to the outside atmosphere through the orifice
28
, as shown by arrow
34
.
But the prior art key signal-generating device
10
has some defects. First, the orifice
28
is formed in the base
24
, so the thickness of the base cannot be reduced. Second, while the rubber dome
20
is being fixed onto the thin film circuit board
18
, the orifice
28
must be carefully aligned with an indenture
31
in the glue layer
30
shown in the
FIG. 1
, or the orifice
28
will be blocked by the glue of the glue layer
30
and the key signal-generating device
10
will malfunction.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a key signal-generating device with a trench to release air from the hollow rubber dome to solve the above-mentioned problem.
According to the claimed invention, the key signal-generating device has a trench to release air. The device includes a thin film circuit board set on a base to generate key signals. The thin film circuit board has a top side and at least one trench on the top side. The device also includes at least one hollow rubber dome set on the thin film circuit board that extends out from the top side of the thin film circuit board to provide elastic support for a key structure. The rubber dome has a predetermined space that is filled with air. One end of the trench extends into the predetermined space so that the predetermined space is in communication with the atmosphere. When the key structure is pressed, the rubber dome is squeezed down by the key structure, causing air in the predetermined space to be released to the atmosphere through the trench.
It is an advantage according to the present invention that the key signal-generating device with a trench to release air has a thinner base and is easier to assemble.
These and other objects and the advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
REFERENCES:
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patent: 4322587 (1982-03-01), Burns et al.
patent: 5149923 (1992-09-01), Demeo
patent: 5607048 (1997-03-01), Kaizu et al.
patent: 5664667 (1997-09-01), Kenmochi
patent: 5669486 (1997-09-01), Shima
patent: 5842798 (1998-12-01), Su
patent: 5960942 (1999-10-01), Thornton
patent: 5981890 (1999-11-01), Chen
patent: 6028591 (2000-02-01), Lueders
patent: 6135886 (2000-10-01), Armstrong
patent: 6198060 (2001-03-01), Yamazaki et al.
patent: 6376789 (2002-04-01), Maruyama et al.
Hsu Chien-Shih
Shih Sheng-Fang
Darfon Electronics Corp.
Ghatt Dave A.
Hirshfeld Andrew H.
Hsu Winston
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