Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2002-02-13
2003-08-12
Scott, J. R. (Department: 2832)
Metal working
Method of mechanical manufacture
Electrical device making
C200S516000
Reexamination Certificate
active
06604278
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a movable contact unit, which is typically employed in the operation panel of electronic equipment of various types, and a method of manufacturing the same. It also relates to a panel switch using the movable contact unit and a method of manufacturing the same.
BACKGROUND OF THE INVENTION
In recent years, mobile electronic equipment has expands its type and number. As the electronic equipment becomes compact and lightweight, a smaller and lighter switch has been used for a panel switch for the operation panel of the equipment.
Preferably employed is, in particular, a movable contact unit using a dome-like shaped movable contact that is made of conductive metallic sheet with resiliency. The reason of its popularity is that the movable contact unit can provide: a low profile, positive tactile response in switching operation, and an electrically reliable connection.
Now will be described a conventional movable contact unit and its manufacturing method, and a panel switch using the movable contact unit with reference to FIG.
8
through FIG.
11
.
FIGS. 8 and 9
show a sectional view and an exploded perspective view, respectively, of a conventional movable contact unit.
In
FIG. 8
, base film
51
is formed of an insulating film having flexibility with its outer shape processed into a predetermined shape. Adhesive layer
52
, which is formed all over the lower surface of base film
51
, adhesively holds each top portion of movable contacts
53
to keep each contact separately. Movable contact
53
is made of conductive metallic sheet having resiliency and is processed into dome-like shape.
Movable contact
53
has, as shown in
FIG. 8
, truncated cone-shaped peripheral edge
53
A and generally spherical-shaped center portion
53
B with a slight upward bulge. A drawing process given to the resilient metallic sheet creates smooth contours between center portion
53
B and peripheral edge
53
A. Separator
54
is made of insulating film
54
B having releasable layer
54
A on its surface. Movable contact
53
is sandwiched between separator
54
and base film
51
. Separator
54
is affixed with adhesive layer
52
lying under base film
51
so that the surface being subjected to the release treatment—releasable layer
54
A—covers all over the lower surface of base film
51
.
Separator
54
is tightly affixed with base film
51
, preventing movable contact
53
from corrosion and the like. Separator
54
also prevents adhesive layer
52
from accidentally sticking to other portions, or from getting foreign matters thereon during transportation and/or storage.
A conventional movable contact unit is structured above. As shown in the sectional view of
FIG. 10
, prior to use of such a movable contact unit, after separator
54
is peeled off, movable contacts
53
are affixed to wiring board
56
on which plural fixed contacts
55
(
55
A and
55
B) are disposed so as to correspond each movable contact with the fixed contacts. A panel switch is thus structured.
As illustrated in
FIG. 10
, each central fixed contact
55
A is opposed to the center portion of movable contact
53
, and the bottom edge of peripheral portion of movable contact
53
is mounted on each of outer fixed contacts
55
B. A panel switch unit is thus configured.
Now will be described how such a switch works.
When a depressing force is exerted on movable contact
53
over base film
51
, the dome-like portion of movable contact
53
is flipped with a tactile response. By the flip, a portion, which stays over the top portion of the contact, of the lower surface of base film
51
comes into contact with central fixed contact
55
A via movable contact
53
, so that electric connections are established between contact
55
A and contact
55
B.
On the other hand, when the depressing force is released, movable contact
53
is now flipped back to its original shape by its own resiliency to open electrically between contacts
55
A and
55
B.
As described above, flexible base film
51
has been employed in the conventional movable contact unit and the panel switch using the unit. However, if movable contact
53
is disposed at an area adjacent to the outer edges of base film
51
processed into a predetermined shape, the side of the outer edge of base film
51
has less tightly affixed area. Therefore, an outer edge of adhesive layer
52
under base film
51
cannot hold a tight contact with separator
54
or wiring board
56
. Such poor adhesion of base film
51
has often caused lack of sealing.
In particular, in the case that movable contact
53
has not smooth contours between generally spherical-shaped center portion
53
B and truncated cone-shaped peripheral edge
53
A, for example, having a stepped transitional portion in the contour, base film
51
tends to have an air-contained spot thereunder. This forces manufactures to add an extra step checking the unit for the sealing condition by visual inspection.
Besides, the poor sealing described above further causes an undesired phenomenon: it adversely affects connection reliability of the switch section of the panel switch.
That is, in a movable contact unit having such a poor sealing condition, there is a possibility that foreign matters creep into an opening formed between adhesive layer
52
and separator
54
during transportation and/or storage of the movable contact unit. Another possibility is, as the arrow indicated by a dotted line in the partially enlarged sectional view of the outer shape portion in
FIG. 11
shows, foreign matters can enter through an opening between adhesive layer
52
and wiring board
56
, after the both has been affixed together.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to provide a highly dustproof movable contact unit and its manufacturing method, and to provide a panel switch using the movable contact unit.
The movable contact unit of the present invention includes a movable contact, a base film, and a separator.
The movable contact is made of resilient conductive metallic sheet, which is formed into a bottom-open, dome-like shape. The base film holds the movable contact with the adhesive layer that is formed under the base film. The base film has sections corresponding to the movable contacts, which are formed into projections fitting with the dome-like shaped movable contact. As for the separator, the release treatment-provided upper surface of the separator is affixed with the adhesive layer lying under the base film. The root portion of the dome-like projection corresponding to the movable contact is tightly affixed to the separator by the adhesive layer under the base film.
The manufacturing method of the movable contact unit of the present invention contains the steps below:
(a) forming the adhesive layer beneath the insulating film-made base film.
(b) allowing the adhesive layer to adhesively hold the top portion of the bottom-open, dome-like shaped movable contact that is made of resilient conductive metallic sheet.
(c) following the step (b), affixing the release treatment-provided upper surface of the separator with the adhesive layer, with the movable contact being sandwiched between the base film and the separator.
(d) following the step (c), applying heat and pressure to the both outer sides of the affixed base film and the separator, thereby:
i) forming the sections corresponding to the movable contacts on the base film into projections fitting with the dome-like shaped movable contact.
ii) firmly affixing the root portion of the dome-like projection that corresponds to the shape of the movable contact to the separator through affixing the adhesive layer to the separator.
The panel switch of the present invention includes a movable contact, a base film, and a wiring board.
In the movable contact unit, the movable contact is made of resilient conductive metallic sheet and is formed into a bottom-open, dome-like shape. The base film of the unit holds the movable contact with the adhesive layer formed beneath the base film. The base film
Nasu Tetsutaro
Okamoto Yuji
Sera Naoki
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Manufacturing method for panel switch using movable contact... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Manufacturing method for panel switch using movable contact..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Manufacturing method for panel switch using movable contact... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3093791