Key switch used in a keyboard

Electricity: circuit makers and breakers – Solid contact – Push button operated

Reexamination Certificate

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Details

C200S0050EA

Reexamination Certificate

active

06268578

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a key switch device suitable for use in a keyboard used as an input device of a personal computer, a word processor, or various other devices, and more particularly to a guide supporting mechanism for guiding and supporting a key top between a raised position and a lowered position.
2. Description of the Related Art
FIGS. 6
to
8
illustrate a conventional key switch device of the above-described type. The key switch device comprises a key top
41
molded from synthetic resin such as ABS resin; a holder member
52
disposed below the key top
41
; a guide supporting member
44
for guiding and supporting the key top
41
between a raised position situated away from the holder member
52
and a lowered position situated close to the holder member
52
; a switch member
57
mounted to the top surface of the holder member
52
; and a rubber spring
58
disposed between the key top
41
and the switch member
57
.
A character (not shown), such as a letter of the alphabet, is printed on the top surface of the key top
41
. As shown in
FIG. 6
, rotary stopper sections
42
and sliding stopper sections
43
are integrally formed with the key top
41
so as to extend downward from the lower surface of the key top
41
. A stopper hole
42
a
is formed in each rotary stopper section
42
, while a stopper hole
43
a
is formed in each sliding stopper section
43
.
The guide supporting member
44
comprises first and second link members
45
and
48
molded from synthetic resin material. As shown in
FIG. 7
, the first link member
45
is formed into a substantially U shape by a pair of arms
46
parallel to each other, and a connecting section
47
which integrally connects the pair of arms
46
. A stopper pin
46
a
protrudes outward from one end of each arm
46
, while a stopper pin
46
b
protrudes outward from the other end of each arm
46
. A shaft hole
46
c
is formed in the center portion of each arm
46
so as to oppose each other.
The second link member
48
comprises a base section
49
including a circular hole
49
a
, and a pair of arms
50
formed consecutively at one end of the base section
49
so as to be parallel to each other. A stopper protrusion
50
a
protrudes from one end of each arm
50
. A pair of outwardly protruding stopper pins
49
b
are formed on the opposite end of the base section
49
. Outwardly protruding shafts
49
c
are provided on opposing ends of the base section
49
.
As shown in
FIG. 6
, the first and second link members
45
and
48
are disposed so as to cross each other in an X-shaped configuration by positioning the base section
49
of the second link member
48
at the inner side of the pair of arms
46
of the first link member
45
and fitting the shafts
49
c
of the base section
49
into the corresponding shaft holes
46
c
in the arms
46
. Crossing sections
51
formed by the shafts
49
c
and the shaft holes
46
c
allow the first and second link members
45
and
48
to rotate with respect to each other. The stopper protrusions
46
b
of the first link member
45
are slidably stopped in the corresponding stopper holes
43
a
in the key top
41
, while the stopper pins
49
b
of the second link member
48
are rotatably stopped in the corresponding stopper holes
42
a
in the key top
41
.
The holder member
52
is a metallic flat plate, and, as shown in
FIG. 7
, has a pair of slits
53
a
and
53
b
parallel to and opposing each other. When a flat-plate portion between the slits
53
a
and
53
b
is made to protrude thereabove from below, a sliding stopper section
54
including a stopper hole
54
a
is formed. In addition, two pairs of slits
55
a
and
55
b
are formed in the holder member
52
so as to be separated from the pair of slits
53
a
and
53
b
in a longitudinal direction thereof and so as to be parallel thereto. When a flat-plate portion between each pair of slits
55
a
and
55
b
is made to protrude thereabove from below, a rotary stopper section
56
including a stopper hole
56
a
is formed between its corresponding pair of slits
55
a
and
55
b.
The stopper pins
46
a
of the first link member
45
are rotatably stopped by the stopper holes
56
a
in the corresponding rotary stopper sections
56
, while the stopper protrusions
50
a
of the second link member
48
are slidably stopped by the stopper holes
54
a
in the sliding stopper section
54
. The rotary stopper sections
56
at the holder member
52
are made to correspond with the sliding stopper sections
43
of the key top
41
by the first link member
45
, while the sliding stopper section
54
of the holder
52
is made to correspond with the rotary stopper sections
42
at the key top
41
by the second link member
48
.
The switch member
57
is formed by placing a top sheet, a spacer, and a bottom sheet upon each other in that order. The top sheet, spacer, and bottom sheet are not shown. Contact electrodes are formed on the bottom surface of the top sheet and the top surface of the bottom sheet, and are separated by a predetermined distance by the spacer so as to oppose each other. The bottom surface of the bottom sheet is brought into contact with the top surface of the holder member
52
in order to mount the switch member
57
to the holder member
52
with a suitable means, such as an adhesive.
The rubber spring
58
is formed of a rubber material and has a reversed conical shape. As shown in
FIG. 6
, it has an annular bottom section
58
a
which supports a top section
58
c
through a thin resilient wall
58
b
, and an actuating protrusion
58
d
formed on the lower surface of the top section
58
c
. The rubber spring
58
is disposed between the key top
41
and the switch member
57
by affixing the annular bottom section
58
a
to the top sheet of the switch member
57
; is in contact with the bottom surface of the key top
41
as a result of inserting the top section
58
c
into the hole
49
a
in the second link member
48
; and supports the top key
41
at a raised position situated away from the holder member
52
as a result of cooperating with the guide supporting member
44
. The actuating protrusion
58
d
is opposed to the top surface of the top sheet in correspondence with the locations where the contact electrodes on the switch member
57
are formed.
In the key switch device having the above-described structure, when the operator presses the top surface of the key top
41
, the key top
41
moves downward, causing the stopper protrusions
46
b
of the first link member
45
to slide in the stopper holes
43
a
in their corresponding stopper sections
43
in the direction of arrow G, and the stopper pins
49
b
of the second link member
48
to rotate in the stopper holes
42
a
in their corresponding rotary stopper sections
42
. At the same time, the stopper pins
46
a
of the first link member
45
rotate in the stopper holes
56
a
in the rotary stopper sections
56
, and the stopper protrusions
50
a
of the second link member
48
slide in the stopper holes
54
a
in the sliding stopper section
54
in the direction of arrow G.
This causes the first and second members
45
and
48
to be pushed downward as they rotate with the crossing sections
51
serving as a fulcrum, so that the key top
41
which is guided by the first and second link members
45
and
48
move downward along with the crossing sections
51
. When the key top
41
moves downward, the rubber spring
58
is pushed downward by the key top
41
, so that the resilient wall
58
b
is buckled, whereby a tactile feel is experienced. Immediately thereafter, as shown in
FIG. 8
, the key top
41
is positioned at a lowered position situated close to the holder member
52
, and the actuating protrusion
58
d
presses and flexes the top sheet of the switch member
57
. Therefore, the contact electrode on the top sheet comes into contact with the contact electrode on the lower sheet, thereby bringing these contact electrodes into electrical conduction, and turning on the

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