Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Reexamination Certificate
1999-11-02
2001-05-22
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
C200S344000
Reexamination Certificate
active
06236003
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a keyboard assembly, particularly a keyboard assembly suitable for use in an input device such as a word processor or a personal computer.
2. Description of the Related Art
A conventional keyboard assembly used in such an input device is shown in
FIGS. 10 and 11
. As shown in both figures, a membrane switch is placed on a support plate (not shown), the membrane switch comprising a lower sheet
50
having a fixed contact (not shown) on a lower side thereof and a flexible upper sheet
52
having a movable contact (not shown) and disposed on the lower sheet
50
through an insulating spacer
51
.
A support member
53
formed of a resin material is disposed on the membrane switch. The support member
53
is provided with two engaging portions
53
a
each having an engaging portion
53
b
and formed on the left-hand side in the figures and is also provided with engaging portions
53
c
each having an engaging hole
53
d
and formed on the right-hand side.
A hole
53
e
is formed between the left- and right-hand side engaging portions
53
a
,
53
c
.
A first lever
54
formed of a resin material is provided with a pair of arm portions
54
c
and a pair of arm portions
54
d,
each pair having a pair of columnar protrusions
54
a
and
54
b
at end portions thereof, with outwardly projecting pivot shaft portions
54
e
being formed at central positions of the arm portions
54
c
and
54
d
. The protrusions
54
b
are pivotably engaged respectively with the engaging portions
53
d
of the support member
53
.
Outside the first lever
54
is disposed a second lever
55
formed of a resin material. As shown in
FIG. 11
, the second lever
55
comprises a connecting portion
55
a
positioned on the right-hand side and a pair of arm portions
55
b
extending leftwards respectively from upper and lower ends of the connecting portion
55
a.
The second lever
55
is formed in a generally turned square U-shape.
At both ends of the connecting portion
55
a
are formed outwardly projecting columnar protrusions
55
c
respectively, and at the left-hand ends of the paired arm portions
55
b
are formed outwardly projecting columnar protrusions
55
d
respectively. A generally elliptic recess
55
e
is formed centrally in each of the paired arm portions
55
b.
The protrusions
55
d
are pivotably engaged respectively with the engaging portions
53
a
of the support member
53
, and the pivot shaft portions
54
e
of the first lever
54
are fitted in the recesses
55
e
respectively. In this way the first and second levers
54
,
55
are assembled crosswise.
For mounting the first and second levers
54
,
55
to the engaging portions
53
a
and
53
c
of the support member
53
, the first and second levers
54
,
55
are held in the crosswise assembled state, and in this state the protrusions
54
b
are fitted in the engaging holes
53
d
of the engaging portions
53
c
while expanding the arm portions
54
d
of the first lever
54
outwards.
Further, the arm portions
55
b
of the second lever
55
are narrowed on the side where the protrusions
55
d
are formed, by applying a force to the arm portions inwards, and the protrusions
55
d
are allowed to fit in the engaging holes
53
b
of the engaging portions
53
a
, whereby the first and second levers
54
,
55
can be secured pivotably to the support member
53
.
A key top
56
is formed using a resin material, and on the left-hand side of the back of the key top
56
are formed a pair of holding portions
56
b
in an opposed relation to each other, with slide grooves
56
a
being formed outwards in the paired holding portions
56
b
respectively. On the right-hand side of the back of the key top
56
are formed a pair of holding portions
56
d,
with slide grooves
56
c
being formed inwards and opposedly to each other in the holding portions
56
d
respectively.
The protrusions
54
a
of the first lever
54
are slidably held respectively by the left-hand holding portions
56
b,
while the protrusions
55
c
of the second lever
55
are slidably held respectively by the second lever
55
, whereby the key top
56
is mounted vertically to be movable on the first and second levers
54
,
55
.
A domed elastic member
57
formed of an insulating rubber is placed on the membrane switch while being positioned within the hole
53
e
of the support member
53
. An upper end portion of the elastic member
57
is in abutment with the back side of the key top
56
.
The first and second levers
54
,
55
, the key top
56
attached to the levers
54
,
55
, and the elastic member
57
are arranged in plural rows on the membrane switch to constitute the conventional keyboard assembly.
The conventional keyboard assembly thus constructed operates in the following manner. When the key top
56
is brought down, the first and second levers
54
,
55
move pivotally about the protrusions
54
b
and
55
d
which are engaged with the engaging portions
53
a
and
53
c
formed on the support member
53
side, so that the pivot shaft portions
54
e
of the first lever
54
move respectively within the generally elliptic recesses
55
e
of the second lever
55
, and the first and second levers
54
,
55
pivotally move downward while the protrusions
54
a
and
55
c
slide respectively within the slide grooves
56
a
and
56
c
formed on the key top
56
side. The key top
56
is adapted to move down with such pivotal downward movement of the first and second levers
54
,
55
.
As a result of such downward movement of the key top
56
, the elastic member
57
is pressed and collapsed and inverted into a dome shape, whereupon the upper sheet, or a switch substrate,
52
is pushed by an inner projection
57
a
of the elastic member
57
and a circuit contact formed on the switch substrate
52
comes into contact with an electric conductor on the lower sheet, or an insulating substrate,
50
to turn ON the membrane switch.
Upon subsequent relief of the pressure on the key top
56
, the first and second levers
54
,
55
and the key top
56
are forced back to the respective states before the pressing by the elastic force of the elastic member
57
, and the switch substrate
52
which has been pressed down by the elastic member
57
moves out of contact with the insulating substrate
50
and reverts to its initial state by virtue of its own restoring force, so that the membrane switch turns OFF.
In the above conventional keyboard assembly, however, when mounting the first and second levers
54
,
55
to the support member
53
, the respective protrusions
54
b
and
55
d
are attached to the support member
53
while expanding the arm portions
54
d
of the first lever
54
outwards or narrowing the arm portions
55
b
of the second lever
55
inwards, thus giving rise to the problem that the assembling work efficiency is deteriorated.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a keyboard assembly which permits an efficient mounting of the first and second levers
54
,
55
and which is superior in assemblability.
According to the first means adopted by the present invention for achieving the above-mentioned object there is provided a keyboard assembly including a key top having first and second engaging portions and held vertically movably on a substrate which has first and second engaging portions, an elastic member which urges the key top upward, and first and second levers which hold the key top vertically movably, the first and second levers being combined together crosswise through a pivot shaft portion formed between one ends and opposite ends of the first and second levers respectively, the first lever having a first retaining portion for pivotable engagement of one end of the first lever with the first engaging portion of the substrate and also having a second retaining portion for slidable engagement of the opposite end of the first lever with the second engaging portion of the key top, the second lever having a first retaining portion fo
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Friedhofer Michael
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