Note: Descriptions are shown in the official language in which they were submitted.
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SUMMARY OF THE INVENTIO~
This invention relates to electrical connectors and
is particularly concerned with the proklem of attaching leads
of an electrical component to a generally flat member such as
a membrane switch.
One of the objects of the present invention is an elec-
trical connection ~or attaching discrete electrical components
to generally flat members, which connection is easy to make and
reliable in operation.
Another object is an electrical connection which is
inexpensive to form.
Another object is an electrical connection for membrane
switch keyboards which permits connection to a component in a
plane other than that of the membrane switch.
Another object is an electrical connector which utilizes
the inherent tendency of sheet material to remain in a flat con-
dition to assist in securing the component.
Another object is an electrical connection which is
sealed from exposure to the elements.
Other obiects will appear in tile following specifica-
tion, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a top plan view of a membrane switch key-
board, with portions cut away, showing one form of connector
according to the present invention.
Figure 2 is a section taken generally along line 2-
2 of Figure 1.
Figure 3 is a top plan view of a connector according
to the present invention.
Figure 4 is a view similar to Figure 3, showing a con-
nector adapted for an alternate type of component.
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DESCRIPTION OF A PREFERRED BMBODI~ENT
This invention is concerned with electrical connections
to a piece of sheet material having electrical conductors formed
thereon. The invention is particularly adapted for connection
o~ discrete electrical components to a membrane switch panel.
The invention is also directed to connection of discrete elec~
trical components to single-thickness sheets which are not neces-
sarily part of a membrane switch. The sheets have conductive
traces formed thereon ~hich contact the leads of the electrical
component.
Membrane switches are currently used in a variety of
applications including typewriter-like keyboards, hand-held cal-
culators, appliance control panels and cash-registers. Frequent-
ly it is desirable to illuminate a portion of a membrane switch
panel to provide information to the user. This can be accom-
plished by ~he use of a light emitting diode (LED) connected
to the circuitry printed on the membrane switch. The problem
then ~ecomes how to connect the leads of an LED, which are wirest
to the conductive traces on the membrane switch which are gen-
erally silk-screened or painte~ on thin layers of plastic.
Figure 1 shows the connection of the present invention
used in a membrane switch keyboard. The keyboard is shown gen-
erally at 10 and includes a base plate 12, a membrane switch
panel 14, a be~el 16 and keys or actuators 18. The baseplate
2S 12 is formed of rigid material such as aluminum. It forms the
support for the keyboard and has appropriate notches or holes
suitable for mounting the keyboard in some device. The membrane
s~itch 14 may have one or moxe tails 20 with conducti~e traces
extending onto it for connection to external circuitry~ The
membrane switch also has a plurality of holes 22 in line with
similar holes in the baseplate 12. The holes receive legs (not
~9~)~25
shown) on the housings of the keys 18. The legs may be heat
staked to fasten the keys to the baseplate.
Looking at Figure 2, the membrane switch 14 includes
a membrane layer 24, a substrate layer 26 and a spacer 28 between
them. The membrane switch layers are preferably formed of thin
sheets o~ plastic material although it could be made of other
materials. The details of the membrane switch itself are conven-
tional and are not specifically shown. The bezel 16 is an over-
lay which covers the membrane switch 14 and provides a uniform,
finishe~ appearance for the keyboard. The be~el has holes (not
shown) which accommodate the keys 18.
As stated above, it is o~ten desired to provide illu-
minatio~ of the keyboard. Figures 1 and 2 illustrate how this
can be accomplished with the present invention. A tail 30 ex-
tends rom either the membrane layer or the substrate layer~
In the embodiment shown the tail 30 extends from the substrate
26~ The tail 30 has one end attached to the substrate as at
32. The other or free end of the tail 30 can be attached wherever
required. In this embodime~t the free end is attached to the
bezel 16. The tail 30 includes conductive traces 34 which may
be painted or silk-screened or otherwise formed on it. An elec-
trical component such as an LED 36 is positioned between the
tail 30 and the bezel portion of the keyboard. The bezel may
have a small opening for the bulb portion o~ the LED. The leads
38 of the LED contact the traces 34 on the tail. The tail is
adhesively secured to the keyboard, in this case to the bezel
16, with the component disposed between the tail and the key-
board ~o that the tail holds the component in place. In a pre-
ferred embodiment a pad 43 of resi~ient material is placed bet~
~een the tail and the keyboard to compensate for any ~Ineveness
in the keyboard or the tail. It will be understood that adhesive
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s
material is applied to the tail and to the pad so that the tail
is securely held in place~
It will be noted that the free end of the tail is not
restricted to the plane of the membrane switch 14. It can be
connected at locations outside of the plane of the switch. For
example, it may be desirable to connect the tail directly to
the underside of a keytop to illuminate a specific key~ Similar-
ly, the tail need not be parallel to the ed~e of the membrane
switch as shown in Figure 1. It could be arranged at an angle
or it could even be folded as required to locate the free end
of the tail at a desired position. If a tail were folded, one
of the connections .described below could be used to connect the
LED to traces located on the opposite side of the tail from where
the LED is positioned.
Figure 34 shows another form of connector for attaching
a discrete electrical component to a piece of sheet material.
The sheet material could be a tail portion of a membrane switch
such as at 30 in Figure 1 or it could be any other piece of flat
material used in an electrical circuit. The sheet material 42
is preferably formed of insulative material such as plast.ic,
paper or the like. Conductive traces 44 and 46 are formed on
the sheet~ The traces may be conductive ink applied by silk-
screening, painting or similar method. A series of slits 48
are cut in the sheet 42. The slits extend at least partially,
and in the embodiment shown wholly, within the area of the con-
ductive traces ~4 and 46. The slits define tabs 50 between them~
The LED 52 has leads 54 and 56 which are interlaced through the
slits to hold the component on the sheet material 42. Since
the natural tendency of the sheet material ~2 is to lie flat,
the tabs 50 will tend to close on the leads $4 and 56. This
natural tendency will therefore ser~e to maintain contact ~et-
ween the conductive traces ~4 and 46 and the leads 54 and 56,
respectively. If desired, the LED 52 can also be secured by
placing a piece of tape 58 over the area of the connection.
Also, the tape will seal the area so there will not be any ex-
posure of the conductive material to the elements.
Figure 4 shows a variation of the connection of Figure
3. In this version U-shaped slits 60 are cut in the area of
the traces 44 and 46. The slits 60 form fingers 62 which can
be bent upwardly, out of the plane of the sheet 42, to receive
the leads of an LE~. This permits accommodation of an LED ~4
having horizontal leads 66 and 68, The leads 66 and 68 are
placed under the fingers 62. The fingers are then pressed back
into the sheet 42 to hold the component to the sheet and insure
electrical contact between the conductive traces and the leads.
As in the embodiment of Figure 3t the finger 62 and the LED 6
may be secured by placing a piece of tape over them. It will
be understood that other types of components could be used in
the connection of the present invention and that the number of
slits could be other than as shown similarly, other changes could
be made in the site and ddisposition of parts without departing
from the spirit and scope of the invention.
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