Typewriting machines – Key-board or key lever-actuating mechanism – Key lever or space-bar mounting structure
Reexamination Certificate
2000-04-26
2001-12-11
Colilla, Daniel J. (Department: 2854)
Typewriting machines
Key-board or key lever-actuating mechanism
Key lever or space-bar mounting structure
C400S490000, C400S491200, C200S344000, C200S345000
Reexamination Certificate
active
06328489
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a key mechanism, and more particularly, to a key mechanism in a computer keyboard.
2. Description of the Prior Art
Please refer to
FIG. 1
an FIG
2
.
FIG. 1
is a schematic diagram of the key mechanism
11
of the prior art.
FIG. 2
is a perspective view of the connecting device
17
of the key mechanism
11
shown in FIG.
1
. The key mechanism
11
comprises a keycap
12
, a base plate
14
set up below the keycap
12
, a connecting device
17
connected between the keycap
12
and the base plate
14
for up-and-down movably installing the keycap
12
on the base plate
14
, and a resilient element
19
installed under the keycap
12
for elastically supporting the keycap
12
in the upward direction and pressing downward on a pressure sensor (not shown) to generate a key-pressing signal. The connecting device
17
further comprises a first connecting piece
23
and a second connecting piece
24
pivotally connected to each other at their center portions
25
and
27
of the first connecting piece
23
and second connecting piece
24
respectively.
The first connecting piece
23
further comprises a front end
21
and a rear end
22
while the second connecting piece
24
comprises a front end
26
and a rear end
28
. The center portion
15
at the front end
21
of the first connecting piece
23
is slidably connected to a corresponding guide channel
29
installed on the base plate
14
while the left and right sides of the rear end
22
are pivotally connected to the keycap
12
. The left and right sides of the front end
26
of the second connecting piece
24
are slidably connected to the keycap
12
while the left and right sides of the rear end
28
are pivotally connected to the base plate
14
. Therefore, in the key mechanism
11
, the connecting device
17
uses a “three-point connection”, making contact with the base plate
14
at three points: the center portion
15
at the front end
21
of the first connecting piece
23
as the first point, and the left and right sides of the rear end
28
of the second connecting piece
24
as the second and third points.
Please refer to FIG.
3
and FIG.
4
.
FIG. 3
is a schematic diagram of another key mechanism
10
of the prior art and
FIG. 4
is a perspective view of the connecting device
16
of the key mechanism
10
shown in FIG.
3
. Similar corresponding elements and component numbers are used in FIG.
3
,
4
as they are in FIG.
1
,
2
. The main difference between the key mechanisms
10
and
11
is that the connecting device
16
shown in
FIG. 3
,
4
utilizes a four-point connection while the connecting device
17
in
FIG. 1
,
2
uses a three-point connection. As shown in
FIG. 4
, the connecting device
16
comprises a first connecting piece
18
and a second connecting piece
9
. The left and right sides of the front end
20
of the first connecting piece
18
are slidably connected to guide channels
27
installed on the base plate
14
. The left and right sides of a rear end
22
of the first connecting piece
18
are slidably connected to the keycap
12
. The left and right sides of a front end
26
and a rear end
28
of the second connecting piece
9
are slidably and pivotably connected to the keycap
12
and base plate
14
respectively. Therefore, the connecting device
16
utilizes a “four-point connection” to connect to the base plate
14
by using the left and right sides of the front end
20
of the first connecting piece
18
as the first and second points and the left and right sides of the rear end
28
of the second connecting piece
9
as the third and fourth points.
Because of the continuing trend towards lighter and thinner keyboards, the internal components must also be made lighter and thinner. In order to meet these design requirements, the torsional strength of the first connecting pieces
23
and
18
is now relatively lower. These pieces are very susceptible to warping as they are the weakest elements in the entire key mechanism, especially when they are placed under an external force which is not in the center of keycap
12
. This is especially true for long keys, such as the space bar.
There are two loading cases to be considered in the written description of the present invention. Loading case I is a balanced external force applied to the center of an element, or no force applied to the element. Loading case II is an unbalanced force applied to an element at an off-center point of the element.
Please refer to FIG.
5
and FIG.
6
.
FIG. 5
is the schematic diagram of warping under loading case II of the front end
21
of the first connecting piece
23
in the connecting device
17
shown in FIG.
1
and FIG.
2
.
FIG. 6
is a schematic diagram of warping under loading case II of the front end of the first connecting piece
18
in the connecting device
16
shown in FIG.
3
and FIG.
4
.
As shown in
FIG. 5
, the central portion
15
will be deformed and bent downward, as indicated by the dotted lines, due to the constraints of the guide channel
29
and the base plate
14
. As shown in
FIG. 6
, when the connecting device
16
is under loading case II, the central portion of the front end
20
of the connecting piece
18
will be deformed and bent upward, as shown by the dotted lines, due to the constraints of the guide channels
27
and lack of constraint at the central portion
39
.
The warping of the first connecting pieces
23
and
18
will result in an unbalanced force being applied to the resilient element
19
, and this unbalanced force will result in unstable key-press signals. Unstable key-press signals produce bad input, especially when a key is being held down.
SUMMARY OF THE INVENTION
Therefore, the main object of the present invention is to provide a key mechanism used in computer keyboards to resolve the above-mentioned problems.
In a preferred embodiment, the present invention provides a key mechanism used in a computer keyboard. The key mechanism comprises a keycap, a base plate, a connecting device and a resilient element. The connecting device moveably connects the keycap to the base plate, and the resilient element provides elastic, upward support for the key cap. The base plate has three guide channels that engage with the connecting device. The connecting device comprises a first connecting piece and a second connecting piece. Central portions of left and right ends of the connecting pieces are pivotally connected together in a scissors-like manner. Left, right and central points on a front end of the first connecting piece are slidably and separately received in the three guide channels of the base plate. A rear end of the first connecting piece is pivotally mounted to the underside of the keycap. The front and rear ends of the second connecting piece may be slidably or pivotally mounted to the keycap or base plate, respectively.
It is an advantage of the present invention that this design prevents warping of the first connecting piece when the keycap is depressed by an unbalanced external force, thereby ensuring more stable key-press signals.
This and other objectives 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 which is illustrated in the various figures and drawings.
REFERENCES:
patent: 5399822 (1995-03-01), Sato et al.
patent: 5947616 (1999-09-01), Liang
patent: 6040541 (2000-03-01), Li
patent: 6056459 (2000-05-01), Tsai
Acer Peripherals Inc.
Colilla Daniel J.
LandOfFree
Key mechanism in a computer keyboard does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Key mechanism in a computer keyboard, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Key mechanism in a computer keyboard will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2595066