Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2002-10-17
2004-11-09
Mai, Ann (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
C200S512000
Reexamination Certificate
active
06815627
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a keyswitch structure for computer keyboard, especially to a keyswitch structure using metal balance rod for larger keycap.
BACKGROUND OF THE INVENTION
Keyboards are popular input device for people in information processing unit such as computer and apparatus requiring frequent input such as cash register. Therefore, the keyboards are under extensive research to provide better performance such as good tactile feel, movement, sound and balance.
Conventional keyswitches with lever mechanism (scissors type keyswitch) are extensively used in keyboard for notebook computer. However, the keyswitch with larger keycap (such as double cap size or triple cap size) has the problem of tilt key cap because larger size and unbalance force (force not at the center of the keycap). The keyswitch with larger key cap are liable to malfunction or the data cannot be exactly input. To overcome this problem, a resilient metal balance rod is provided between the cap and the base of the keyswitch.
FIGS. 1
,
2
and
3
show a conventional keyswitch with a keycap
10
a
, a first lever
11
a
, a second lever
12
a
, a base
13
a
and a balance rod
14
a
, wherein the first lever
11
a
and the second lever
12
a
are cross to each other. The first lever
11
a
has a pivotal shaft
15
a
pivotally connected to a pivotal stage
17
a
on the base
13
a
and the second lever
12
a
has a pivotal shaft
16
a
pivotally connected to a pivotal stage
18
a
on the base
13
a
, respectively. Each of the first lever
11
a
and the second lever
12
has a top end connected to a bottom face of the keycap
10
a
, whereby the first lever
11
a
and the second lever
12
form a lever mechanism.
The first lever
11
a
of the lever mechanism has a bump
19
a
placed at a lower center end thereof and the base
13
a
has a flange
20
a
on top face thereof and corresponding to the bump
19
a
. The bump
19
a
is in contact with and clamped by the flange
20
a
during downward stroke of the keycap
10
a.
The balance rod
14
a
is a metal rod of U shape and has a center rod section
21
a
pivotally connected to bottom of the keycap
10
a
and two lateral rod sections
22
a
. Each of the lateral rod sections
22
a
is pivotally connected to a rounded holes
24
a
of in a groove
23
a
of the base
13
a
. The rounded holes
24
a
extends along horizontal direction and is higher than a top face of the base
13
a
. The provision of the balance rod
14
a
enables a force exerting on the keycap
10
a
being concentrated at center of the keycap
10
a
such that the keycap
10
a
can be stably moved upward and downward as shown in
FIGS. 2 and 3
.
A rubber dome
25
a
is placed between the keycap
10
a
and the base
13
a
. When the keycap
10
a
is guided by the lever mechanism for vertical up and down movement, the rubber dome
25
a
below the keycap
10
a
will detach from. or touch a flexible circuit board
26
a
on the base
13
a
and a switch on the flexible circuit board
26
a
is turned off or on.
However, to allow a rotational movement of the balance rod
14
a
, a larger contact allowance is provided for the rounded holes
24
a
through which the lateral rod sections
22
a
passes, as shown in FIG.
2
A and FIG.
3
A. The larger contact allowance is the source of noise in current keyboard for notebook computer. Moreover, if the lateral rod section
22
a
has larger contact area with the rounded hole
24
a
, noise is also liable to occur.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a keyswitch structure for keyboard of notebook computer, wherein the keyswitch structure has reduced gap between the balance rod and the base, and reduced noise.
It is another object of the present invention to provide a keyswitch structure for keyboard of notebook computer, wherein the keyswitch has a hook atop a groove thereof to provide more restriction on the stroke thereof.
To achieve above object, the present invention provides a keyswitch structure for keyboard of notebook computer comprising a keycap, a first lever, a second lever, a base and a balance rod. The base has two holed groove lugs. Each lug has a rectangular hole. The rectangular hole has an accommodating section on a bottom side thereof which lowers relative to a top face of the base. The balance rod has a center rod section and two lateral rod sections vertically extending from two ends of the center rod section. The center rod section is pivotally connected to the connection stage of the keycap and the two lateral rod sections pass through and are enclosed by the rectangular holes. The keyswitch structure has a reduced gap between the balance rod and the base and the keyswitch structure has reduced noise.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and in which:
REFERENCES:
patent: 4771146 (1988-09-01), Suzuki et al.
patent: 5823325 (1998-10-01), Lin
patent: 6057522 (2000-05-01), Chao
patent: 6100482 (2000-08-01), Koma et al.
patent: 6495782 (2002-12-01), Huang
Fishman M.
Lite-On Technology Corporation
Mai Ann
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