Key input device and portable telephone incorporating same

Details Key input device and portable telephone incorporating same Key input device and portable telephone incorporating same

2001-04-04

2003-11-04

Bella, Matthew C. (Department: 2676)

Computer graphics processing and selective visual display system

Display peripheral interface input device

Including keyboard

C345S168000, C345S172000, C345S160000, C341S022000

Reexamination Certificate

active

06642920

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to key input devices for use in portable telephones and the like, and more particularly to a seesaw key input device adapted to selectively close a plurality of key contacts.
BACKGROUND OF THE INVENTION
With reference to
FIG. 4
, portable telephones usually have a casing
1
formed by a front case
11
and a rear case
12
. Arranged on the surface of the front case
11
are a display
13
, a plurality of manual keys
14
including numerical keys, and a seesaw key
15
to be manipulated in selecting a desired function. The illustrated seesaw key
15
is depressed downwardly or is inclined to forward, back, left, or right, so that one of five key contacts is adapted to selectively be closed, with the result that one desired function is selected and set.
The casing
1
has a circuit board
3
disposed in its interior as shown in FIG.
5
. Arranged on the circuit board
3
are a sheet key assembly
40
to be depressed by the manual keys
14
and the seesaw key
15
, a display
13
, a high-frequency circuit module
32
, and a vibrator
2
comprising a motor
22
and an eccentric weight
21
attached to the output shaft of the motor for notifying the user of incoming calls, etc.
The sheet key assembly
40
, as already known, has a dome sheet of PET comprising a plurality of dome portions disposed over a base plate. The dome portion is elastically restorably invertable by depressing force of the manual key to bring a contact terminal formed on the inner surface of the dome portion into contact with a contact electrode formed on the surface of the base plate to close contacts.
As shown in
FIG. 6
, arranged below the seesaw key
15
is a seesaw key assembly
9
having a stick
90
extended. The seesaw key assembly
9
is fixed to the surface of the dome sheet
41
forming a surface portion of the sheet key assembly
40
. An end portion of the stick
90
of the seesaw key assembly
9
is fixed jointly to the rear surface of the seesaw key
15
. As described above, the seesaw key
15
is manipulated into being depressed to depress the stick
90
downwardly, or is inclined to forward, back, left, or right, whereby a contact out of five contacts which is incorporated in the seesaw key assembly
9
can be closed.
A key rubber
80
is provided on the surface of the dome sheet
41
constituting the sheet key assembly
40
, and covers a plurality of dome portions (not shown) formed with the sheet key assembly
40
. The key rubber
80
is provided with an opening
80
a
on a region wherein the seesaw key assembly
9
is to be installed, and the seesaw key assembly
9
is installed in the opening, whereby the seesaw key assembly
9
has its rear surface contacted with the surface of the dome sheet
41
, and is surface-mounted on the dome sheet
41
.
An annular waterproof member
91
is interposed between the outer peripheral surface of the seesaw key assembly
9
and the inner peripheral surface of the opening
80
a
of the key rubber
80
. Accordingly, water ingressing from its surroundings can be prevented from reaching the surface of the dome sheet
41
.
However, with the conventional portable telephone having a stick-like seesaw key assembly
9
installed, as shown in
FIG. 6
, the stick
90
needs to have some height since the inclination of the stick
90
causes the seesaw key assembly
9
to close the terminals, thus entailing the problem of increasing the thickness of the portable telephone. Due to the waterproof construction of interposing the waterproof member
91
between the seesaw key assembly
9
and the key rubber
80
, the waterproof member is required, increasing the number of components. Further, there is likelihood that water may ingress from between the seesaw key assembly
9
and the waterproof member
91
, or from between the key rubber
80
and the waterproof member
91
, giving rise to another problem of insufficient waterproof.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a key input device which is adapted to make the device more thinner and to make the device waterproofed completely with reduced number of components, and a portable telephone incorporating the key input device.
The key input device of the present invention comprises a seesaw switch unit
4
mounted on a base, and a key rubber
8
installed on the base covering the seesaw switch unit
4
. Provided on the surface of the key rubber
8
is a seesaw key
10
to depress the seesaw switch unit
4
.
The seesaw switch unit
4
comprises a base plate
5
, a dome sheet
7
provided over the base plate
5
having a plurality of dome portions
71
,
72
, a pivotally movable member
6
provided over the dome sheet
7
to selectively depress each dome portion
71
. The seesaw key
10
is installed over the pivotally movable member
6
. The pivotally movable member
6
is depressed by the manipulation of the seesaw key
10
to make a dome portion elastically restorably invertable to bring a contact terminal
52
provided on the inner surface of the dome portion into contact with a contact electrode
51
provided on the surface of the base plate
5
, with the result that the contacts are closed.
With the key input device of the invention, the seesaw switch unit
4
is used in place of a conventional stick-like seesaw key device
9
. The seesaw switch unit
4
can be made thinner, so that the entire device is adapted to be made thinner. Further, since the seesaw switch unit
4
is adapted to close its contacts by exerting a depressing force on the pivotally movable member
6
, the seesaw switch unit
4
installed directly on the surface of the base is covered with the key rubber
8
having no opening, and the depression of the seesaw key
10
provided on the surface of the key rubber
8
activates the seesaw switch unit
4
. Accordingly, the key rubber has no opening as in the prior art, so that the complete waterproof construction is achieved and there is no need of the conventional waterproof member.
Stated specifically, the key rubber
8
comprises a flat plate portion
82
affixed to the rear surface of the seesaw key
10
, a slanting portion
83
formed by defining the flat plate portion
82
, a grounding portion
84
formed by defining the slanting portion
83
. The slanting portion
83
is so inclined from the flat plate portion
82
to the grounding portion
84
as to be positioned at a lower level toward the base, and the grounding portion
84
is in close contact with the surface of the base.
Stated more specifically, when the seesaw key
10
is depressed to move the pivotally movable member
6
, the flat plate portion
82
of the key rubber
8
is depressed by the rear surface of the seesaw key
10
to have the flat plate portion
82
inclined, having the slanting portion
83
of the key rubber
8
elastically deformed. The slanting portion
83
is inclined toward the grounding portion
84
, so that the slanting portion
83
can be elastically deformed spontaneously, and the portion is deformed in a relatively small amount. Therefore, even if the key rubber
8
is repeatedly stressed by the repeated manipulation of the seesaw key
10
, there is no likelihood of cracking, etc. on the key rubber
8
.
Further stated specifically, the central portion of the rear surface of the seesaw key
10
and the central portion of the surface of the flat plate portion
82
are affixed to each other. The seesaw key
10
contacts with the flat plate portion
82
of the key rubber
8
so as to be relatively movable each other around the affixed portion.
Further stated more specifically, when the seesaw key
10
is depressed to move the pivotally movable member
6
, the flat plate portion
82
of the key rubber
8
is depressed by the rear surface of the seesaw key
10
to have the flat plate portion
82
inclined and to have the slanting portion
83
elastically deformed. While the seesaw key
10
and the flat plate portion of the key rubber
8
are affixed only at each central portion thereof, the surrounding portion is not affixed and is relat

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