Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2001-05-23
2002-03-12
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
Reexamination Certificate
active
06355894
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a keyboard that drives a membrane switch by tactile-response collapsible or flip-over domes, and a method of making the keyboard.
A description will be given first, with reference to
FIGS. 1
to
4
, of a prior art example.
In
FIG. 1
, reference numeral
10
denotes a keyboard substrate made of a metal sheet or sheet of synthetic resin that has the same mechanical strength as does the metal sheet. Reference numeral
13
denotes a keyboard frame made of a metal sheet or sheet of synthetic resin that has the same mechanical strength as does the metal sheet. The substrate
10
has bumps
11
arranged in matrix form. The substrate
10
and the frame
13
overlying it are welded, fused or bonded together through the bumps
11
to define therebetween a gap in which to house a membrane switch sheet
20
described later on. Incidentally, the substrate
10
and the frame
13
are coupled together in the final step of the manufacturing process of the keyboard switch.
The frame
13
has, as depicted in
FIGS. 3A and 4
, punched-out openings
31
each corresponding to one of switch portions
20
S of the membrane switch sheet
20
that are arranged in matrix form; hence, the openings
31
correspond to keytops
4
, too). The membrane switch sheet
20
, which is received in the gap defined by the substrate
10
and the frame
13
, is composed of a movable contact sheet
21
, a spacer
22
and a fixed contact sheet
23
. The spacer
22
has punched-out contact areas
221
. As depicted in
FIG. 4
, the movable contact sheet
21
has on the underside thereof a movable contact
211
and the fixed contact sheet
23
has on the top thereof a fixed contact
231
disposed opposite the movable contact
211
. The contact area
221
, the movable contact
211
, the fixed contact
231
and the keytop
4
, described later on, are positioned relative to one another to form the switch portion
20
S. A plurality of such switch portions
20
S are arranged in matrix form to provide the keyboard switch.
Reference numeral
4
denotes the keytop mentioned above. As shown in
FIG. 1
, the keytop
4
and the frame
13
are mechanically linked by a pantographic lifting or support frame
50
interposed therebetween. The pantographic support frame
50
has, as depicted in
FIG. 2A
, a first coupling rod
52
, a pair of first links
5
each connected at one end to one of opposite ends of the first coupling rod
52
at right angles thereto and extending therefrom substantially in parallel with the other, a second coupling rod
63
, and a pair of second links
6
each connected at one end to one of opposite ends of the second coupling rod
63
at right angles thereto and extending therefrom substantially in parallel with the other. The second links
6
are coupled together by a semicircular coupling portion
64
formed integrally therewith nearer their free ends than their centers so that an insertion hole
65
is defined by the coupling rod
63
and a semicircular coupling portion
64
for receiving a tactile-response collapsible dome. The first links
5
and the second links
6
are combined, with the outside surfaces of the latter intermediately of their ends held in contact with the inside surfaces of the central portions of the former intermediately of their ends. The first and second links
5
and
6
are connected centrally thereof by shafts
60
in a manner to be rotatable relative to each other as depicted in FIG.
1
.
The keytop
4
has, as shown in
FIG. 2B
, on the underside thereof along its two opposed sides rotary bearings
41
and slide bearings
42
. The coupling rod
52
, which serves also as a keytop support rotary shaft of the first links
5
, is rotatably received in the rotary bearings
41
of the keytop
4
, whereas keytop support sliding shafts
62
of the second links
6
are slidably received in the slide bearings
42
. As shown in
FIGS. 1
,
2
A,
2
B,
3
A and
3
B, leg slide shafts
51
of the first links
5
are slidably received in leg slide shaft bearings
32
formed by drawing the frame
13
in the vicinity of the switch portion
20
S, and leg rotary shafts
61
of the second links
6
are rotatably received in leg rotary shaft bearings
33
formed by drawing the frame
13
.
As depicted in
FIG. 3A
, the width D
1
of the opening
31
between the leg slide shaft bearings
32
is smaller than the distance between the outermost ends of the leg slide shafts
51
but somewhat larger than the length of the connecting rod
52
so that the first links
5
and the rod
52
are allowed to pass through the opening
31
. Accordingly, when the pantographic support frame
50
is mounted on the frame
13
with the leg rotary and slide shafts
61
and
51
received in the leg rotary and slide shaft bearings
33
and
32
, respectively, in
FIG. 4
, the links
5
and
6
tilt toward the keytop
4
through the opening
31
and the keytop support rotary and slide shafts
52
and
62
engage the rotary and slide shaft bearings
41
and
42
on the underside of the keytop
4
, respectively.
A tactile-response collapsible or flip-over dome
7
(
FIGS. 1 and 2A
) is composed of a cylindrical part
71
firmly fitted on a projection
43
formed on the underside of the keytop
4
centrally thereof, a dome part
72
, a flange part
73
formed integrally with the lower end portion of the dome portion
72
, and a press part
74
formed integrally with the ceiling of the dome portion
72
. The dome
7
is made of rubber or elastic synthetic resin. The dome part
72
is elastically deformed by the cylindrical part
71
that is pressed down upon depression of the keytop
4
, but the flange part
73
is formed thick and hence is not much deformed.
The dome
7
lies between the underside of the keytop
4
and the movable contact sheet
21
of the membrane switch sheet
20
through the opening
31
of the frame
13
and the dome insertion hole
65
, holding the keytop
4
in its raised position. That is, if the dome
7
is not present, the pantographic support frame
50
is lowered and lies flat, but when the dome
7
is interposed between the underside of the keytop
4
and the movable contact sheet
21
of the membrane switch sheet
20
, the keytop is pushed up by the dome
7
and the pantographic support frame
50
is raised almost its full height. The dome
7
has its cylindrical portion
71
engaged with the projection
43
(
FIG. 1
) protrusively provided on the underside of the keytop
4
centrally thereof as mentioned previously. The lower end face of the flange
73
is adhesive bonded to the surface of the movable contact sheet
31
in the vicinity of the opening
31
as indicated by
73
.
Turning next to
FIG. 4
, the assembling of the keyboard will be described below. In
FIG. 4
there are shown parts of only one key of the keyboard with their insides upward.
In the first place, keytops
4
with their undersides upward are arranged in matrix form on an assembly table (not shown) at intervals equal to those of the switch portions
20
S. Then, the frame
13
is placed face down on the assembly table with each opening
31
held in alignment with the corresponding keytop
4
. Then, the pantographic support frame
50
is placed with the keytop support slide shafts
62
engaged with the slide shaft bearings
42
and the coupling rod
52
also serving as the keytop support rotary shaft fitted in the slide shaft bearings
41
, while at the same time the leg slide shafts
51
of the first links
5
are fitted in the leg slide shaft bearings
32
and the leg rotary shaft
61
of the second links
5
is fitted in the leg rotary shaft bearings
33
. Then, the dome
7
with its cylindrical part
71
downward is inserted through the dome insertion hole
65
(
FIG. 2A
) and pressed to put the cylindrical part
71
on the projection
43
of the keytop
4
. Then, an adhesive is applied onto the lower end face of the flange
73
of the dome
7
. Then, the movable contact sheet
21
is placed on the frame
13
and the pantographic support frame
50
with the movabl
Friedhofer Michael
Gallagher & Lathrop
Hosiden Corporation
Lathrop, Esq. David N.
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