U.S. patent number 3,742,157 [Application Number 05/134,715] was granted by the patent office on 1973-06-26 for keyboard switch assembly with improved movable contact.
This patent grant is currently assigned to Lematex, Inc.. Invention is credited to Wayne V. Leposavic.
United States Patent |
3,742,157 |
Leposavic |
June 26, 1973 |
KEYBOARD SWITCH ASSEMBLY WITH IMPROVED MOVABLE CONTACT
Abstract
A multiple switch construction for a keyboard or the like
produced as a flat panel embodying laminates of electrical
conductors in desired patterns, assembled as stratifications in
close proximity and separated by spacers. Individual depressible
means operating through resilient members urge movable switch
elements into contact with fixed electrical conductors with a
rotary, wiping action to insure positive electrical contact.
Inventors: |
Leposavic; Wayne V. (Saratoga,
CA) |
Assignee: |
Lematex, Inc. (Santa Clara,
CA)
|
Family
ID: |
27249524 |
Appl.
No.: |
05/134,715 |
Filed: |
April 16, 1971 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
860861 |
Sep 25, 1969 |
3600528 |
Aug 17, 1971 |
|
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Current U.S.
Class: |
200/5A; 200/278;
200/516 |
Current CPC
Class: |
B41J
5/12 (20130101); H01H 13/80 (20130101); H01H
13/702 (20130101); H01H 13/785 (20130101); H01H
2205/032 (20130101); H01H 13/703 (20130101); H01H
2203/018 (20130101); H01H 2207/022 (20130101); H01H
2229/008 (20130101); H01H 2201/026 (20130101); H01H
2201/004 (20130101); H01H 2229/016 (20130101); H01H
2211/03 (20130101); H01H 2221/05 (20130101); H01H
2229/028 (20130101); H01H 2223/002 (20130101); H01H
2217/024 (20130101); H01H 2203/022 (20130101); H01H
2201/014 (20130101); H01H 2209/01 (20130101) |
Current International
Class: |
B41J
5/00 (20060101); B41J 5/12 (20060101); H01H
13/70 (20060101); H01H 13/702 (20060101); H01h
009/26 () |
Field of
Search: |
;200/5A,159B,166BH,6R,8A,16D,1R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scott; J. R.
Parent Case Text
This is a continuation-in-part of my copending application, Ser.
No. 860,861 now U.S. Pat. No. 3,600,528, issued Aug. 17, 1971,
filed Sept. 25, 1969, entitled MULTIPLE SWITCH CONSTRUCTION.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows.
1. In a multiple switch construction in which stratified laminates
superimposed in spaced relation and in close proximity one upon
another comprise in combination:
1. an electrically non-conductive base panel having one surface
thereof divided into a plurality of switching areas;
2. a fixed electrically conductive switch element fixed upon said
surface of said base panel within each of said switching areas
thereon;
3. depressible means supported on said base panel in spaced
relation to said surface thereof and selectively depressible toward
the latter within any one of said switching areas thereon;
4. a flexible electrically conductive switching element having
frame-like portions thereof conforming to and supported in spaced
relation to said base panel with said depressible means for rotary
flexing movement by the latter into electrical contact with the
particular fixed electrically conductive switch element within the
switching area into which said depressible means is selectively
depressed; and
5. a spring laminate of resilient material interposed between said
depressible means and said flexible switching element, said spring
laminate including a plurality of spring stampings corresponding in
number and location to each of said plurality of switching areas
providing a positive spring return for each of said depressible
means.
2. The multiple switch construction in accordance with that of
claim 1, including in combination:
1. spacers mounted on said one surface of said base panel for
dividing the same into a plurality of switching areas;
2. non-conductive extensions on said spacers disposed on said
frame-like portions of said flexible electrically conductive
element;
3. a plurality of integrated frames formed in said spring laminate
conforming to said non-conductive extensions of said spacers and
secured thereto;
4. a plurality of spider-like legs extending spirally inwardly of
each of said frame-like portions and having inwardly bowed ends
terminating in a common central ring; and
5. a depending central projection on the underside of said
depressible means within each of said switching areas and supported
on said common central ring for engaging said flexible element with
the fixed electrically conductive element on said base panel upon
depression of said depressible means in the respective switching
area.
3. A multiple switch construction as claimed in claim 2 and further
including a layer of resilient, non-conductive material interposed
between said flexible switching element and said spring laminate,
said layer providing a damper for said movable contacts to minimize
contact bounce.
4. A multiple switch construction as claimed in claim 3 wherein
said depressible means is an array of push buttons supported for
linear movement in a guide plate.
5. A multiple switch construction as claimed in claim 1 and further
including a layer of resilient, non-conductive material interposed
between said flexible switching element and said spring laminate,
said layer providing a damper for said movable contacts to minimize
contact bounce.
6. A multiple switch construction as claimed in claim 5 wherein
said depressible means is an array of push buttons supported fro
linear movement in a guide plate.
7. The multiple switch construction in accordance with that of
claim 2 wherein said spring laminate further includes a plurality
of legs having base ends thereof integrally connected to said
common central ring, extending spirally and radially inwardly
therefrom and commonly terminating at their opposite ends to form a
seat for said depending central projection on said depressible
means.
8. In a multiple switch construction having non-conductive spacers
defining independent switch areas, the improvement comprising
switching elements constructed of a panel divided into a plurality
of frame-like portions having integral movable switch elements
suspended from said frame-like portions for rotary flexing movement
toward a base panel, said integral movable switching elements
including:
1. a medial contact means;
2. a plurality of legs having base ends thereof equally spaced
about said medial contact means, said legs being integral to said
frame-like portions and extending across one side of said
frame-like portions and inwardly therefrom into the switching area
defined by said spacers; and
3. each of said legs being of a length greater than the shortest
distance between its base end and said medial contact element to
thereby facilitate flexing of said legs toward said base panel
while supporting said medial contact element parallel thereto for
substantially linear and rotary movement upon depression thereof in
a direction substantially perpendicular to the plane of said
panel.
9. In a keyboard assembly for controlling electrical circuits the
combination comprising:
1. an electrically non-conductive base panel having a plurality of
switch elements fixed therein, said switch elements being divided
into a plurality of independent switching zones by a framework of
spacers;
2. a panel of flexible switching elements supported in spaced
relation to said fixed elements on said spacers;
3. a resilient insulating layer positioned over said flexible
switching elements, said insulating layer having a plurality of
expanded air pockets therein corresponding in number and location
to each of said plurality of switching zones; and
4. a plurality of push buttons supported for linear movement into
each of said independent switching zones.
10. In a multiple switch construction in which stratified laminates
superimposed in spaced relation and in close proximity one upon
another comprise in combination:
1. an electrically non-conductive base panel having one surface
thereof divided into a plurality of switching areas;
2. a fixed electrically conductive switch element fixed upon said
surface of said base panel within each of said switching areas
thereon;
3. depressible means supported on said base panel in spaced
relation to said surface thereof and selectively depressible toward
the latter within any one of said switching areas thereon;
4. a flexible electrically conductive switching element supported
in spaced relation to said base panel with said depressible means
for movement by the latter into electrical contact with the
particular fixed electrically conductive switch element within the
switching area into which said depressible means is selectively
depressed; and
5. a layer of non-conductive resilient material interposed between
said depressible means and said flexible switching element, said
layer having a plurality of expanded portions therein corresponding
in number and location to each of said plurality of switching
areas.
11. A keyboard assembly for controlling electrical circuits
comprising:
1. an array of pushbuttons;
2. a guide plate supporting said push buttons for linear
movement;
3. a layer of resilient material disposed below said push buttons,
said layer having a plurality of expanded portions formed therein
for each of said push buttons in said array;
4. an electrically non-conductive base panel having a plurality of
switch elements fixed thereon;
5. a framework of spacers mounted on said base panel dividing said
fixed switch elements into a plurality of individual switching
areas;
6. a conductive switching panel supported in spaced relation to
said base panel on said spacers and said push buttons, said panel
having a plurality of flexible, movable switch elements formed
therein, each said switch element movable spirally downwardly by
said push buttons against said fixed element within each defined
switching area.
12. A keyboard assembly for selectively controlling electrical
circuits comprising:
1. an electrically non-conductive base panel;
2. electrically conductive switch elements fixed on the upper
surface of said base panel;
3. a framework of spacers mounted on said upper surface of said
base panel dividing the same into a plurality of switching
areas;
4. flexible, electrically conductive switching elements having
frame-like portions thereof conforming to and supported on said
spacers in spaced relation to said base;
5. a sheet of resilient, non-conductive material supported on said
switching elements;
6. a second framework of spacers aligned with said first-mentioned
spacers on said sheet of resilient material;
7. a spring laminate of resilient material having frame-like
portions conforming to and supported on said second framework of
spacers; and
8. an array of pushbuttons supported for linear movement within a
guide plate, said pushbuttons corresponding in location and number
to each of said plurality of switching areas, said push-buttons
being depressible within any one of said switch areas to move said
flexible switch element into contact with said fixed switch element
to thereby selectively close an electrical circuit.
13. The keyboard assembly as claimed in claim 12 wherein said
electrically conductive switching elements comprise;
1. a medial contact means;
2. a plurality of legs having base ends thereof equally spaced
about said medial contact means, said legs being integral to said
frame-like portions and extending across one side of said
frame-like portions and inwardly therefrom into the switching area
defined by said spacers; and
3. each of said legs being of a length greater than the shortest
distance between its base end and said medial contact element to
thereby facilitate flexing of said legs toward said base panel
while supporting said medial contact element parallel thereto for
substantial linear and rotary movement upon depression thereof in a
direction substantially perpendicular to the plane of said
panel.
14. The keyboard assembly as claimed in claim 12 wherein said
spring laminate comprises:
1. a plurality of integrated frames formed in said spring laminate
conforming to said non-conductive extensions of said spacers and
secured thereto;
2. a plurality of spider-like legs extending spirally inwardly of
each of said frame-like portions and having inwardly bowed ends
terminating in a common central ring.
15. In a multiple switch construction having movable switching
elements formed in a panel divided into a plurality of framelike
portions, said elements suspended in said frame for rotary and
flexing movement toward a fixed contact, said elements within each
frame comprising:
a central movable switching element having a plurality of radially
extending contact fingers thereon; a plurality of equally spaced
flexible legs extending outwardly from said switching elements,
said legs turning at an acute angle at a distance away from said
element and extending along the sides of said frame through at
least the greatest part of the length of said side to an adjacent
side for integral connection therewith, said legs forming a
hinge-like connection between said frame and said element whereby
the distance between the ends of said legs and their connection
with said frame changes relative to the vertical as said element is
depressed resulting in a spiralling rotating descent of said
elements and said contact fingers toward said fixed contacts for
rotary wiping contact therewith.
16. The multiple switch construction of claim 15 in which said
contact fingers extend radially inwardly from said central
element.
17. The multiple switch construction of claim 15 in which said
contact fingers extend radially outwardly from said central
element.
18. The multiple switch construction of claim 17 in which the
outermost ends of said radially outwardly extending contact fingers
are bifurcated.
Description
BACKGROUND
This invention relates to multiple switches in a single keyboard
and the like and more particularly to the provision of momentary
switches in large blocks as distinguished from numerous independent
switches assembled into a common block or unit.
Heretofore, most conventional momentary switches of the push button
type have been produced as individual units. Normally, such
individual switches include a plunger which when depressed will
either mechanically engage or magnetically energize a pair of
contacts to close an electrical circuit. In some cases a plunger
carriers a magnet for shifting the latter into a position to excite
or energize an active element to effect a sensor used in a
remaining circuit as an indication of closed contact. Such
momentary switches of the prior art are not conductive to close
proximity of finger tab push buttons as in a keyboard or the like.
This is so because the mounting of individual switches, leverages,
and sensors in close relation becomes a tedious and time consuming
task often fraught with error and faulty connections when later
tested. In some applications such as computer keyboards, electric
typewriters, and the like, the output currents from individual
switches have to be understood by the remaining circuits. Such
encoding usually requires solid state elements such as diodes,
transistors, and/or integrated circuits.
Further, prior art switches have experienced difficulty in not
making a good contact and/or encountering "bounce" so as to create
different signals than those intended by the operator. In other
words, the switches do not reflect the proper signal as each key is
depressed because the movable contact does not make good contact
with the stationary contact or it "bounces" to make several
repetitive improper signals rather than a signal which is desired
for each depression of a key.
THE PRESENT INVENTION
In accordance with the present invention I provide momentary type
switches in large blocks arranged in various configurations and
patterns. This contemplates producing such multiple switches by
photography and chemical milling or metal etching processes.
I also produce multiple switches by the use of printed circuits on
base blocks coordinated with gang contacts produced as metal
stampings, chemical milling, or the like in such a manner as to
require little or no tooling and a minimum of labor in
assembly.
It is a further object to provide a relatively simple and compact
multiple switch assembly with components assembled seriatim over a
flat base block to thereby minimize cost in both assembly and
manufacture. In this connection it is contemplated that the
components of the multiple switches can be formed in any design or
configuration of a keyboard or switch panel as desired superimposed
one above the other whereby upon assembly of such components
complete switching means is achieved.
It is yet another object to mass produce multiple switch panels by
laminates of electrical conductors statified in close proximity for
operation of each individual switch upon finger pressure applied
thereto. In this connection it is contemplated that the laminates
be spaced by dividers beneath individual push buttons or keys
having indicia locating and/or identifying the individual switch
therebelow.
Also, in accordance with this invention is provided a movable
switch contact element having a moment arm to impart a rotary
wiping action thereto as the switch is depressed.
Also provided is a multiple switch construction having individual
push buttons biased toward a first or open position by means of
return springs formed as metal stampings or the like, requiring a
minimum of labor in assembly.
In addition, the assembly minimizes "bounce" by providing a
flexible layer which in one embodiment has a plurality of air
pockets to compensate for the inertia of the movable contact and
prevent it from "bouncing" and producing undesirable signals.
With the foregoing objects in mind it will be understood that the
multiple switches of the present invention contemplate a
construction requiring a minimum of parts within a minimum of
space, eliminating soldering and hand assembly of individual
switches to thereby produce keyboards and switch panels with the
greatest economy.
These and other objects and advantages of the present invention
will become apparent from a reading of the following specification
and accompanying drawings wherein:
FIG. 1 is a plan view of a keyboard embodying the multiple push
button switches of the present invention;
FIG. 2 is an enlarged section through FIG. 1 taken along line 2--2
and showing a first embodiment of the present invention;
FIG. 3 is a fragmentary plan view of one embodiment of the flexible
contact element;
FIG. 4 is a perspective view of the flexible contact element shown
in FIG. 3;
FIG. 5 is an enlarged section similar to FIG. 2 showing the switch
depressed to effect the switching function;
FIG. 6 is a fragmentary plan view of another embodiment of a
flexible contact element;
FIG. 7 is a perspective view of the contact element shown in FIG.
6;
FIG. 8 is a sectional view like FIGS. 2 and 5 showing a preferred
embodiment of the invention;
FIG. 9 is a fragmentary plan view of the push button return spring
utilized in connection with the preferred embodiment shown in FIG.
8;
FIG. 10 is a fragmentary plan view of a flexible contact element
utilized in the preferred embodiment;
FIG. 11 is a fragmentary view similar to FIG. 8 showing a further
modification of the preferred embodiment; and
FIG. 12 is a section through FIG. 2 taken along line 12--12 showing
the fixed contact elements.
Referring to FIGS. 1, 2, 5, and 12, the first embodiment of the
multiple switches of the present invention, as previously disclosed
in U.S. Pat. No. 3,600,528, comprises a non-conductive base panel
20 having a photographically printed circuit etched on its surface
to provide a plurality of fixed contact elements 22 thereon divided
by a screen of spacers 24 into separate switch areas or zones 26.
Each of the contact elements 22 have independent electrical
connection to one side of an electrical circuit through a suitable
plug arrangement 28 which may be formed on the base 20 for mating
with a suitable jack (not shown). The fixed contact elements,
illustrated in detail in FIG. 12, on the upper surface of the base
panel 20 may be arranged in the form of a ring or segments thereof
having an outline configuration compatible with the contact fingers
39 of the movable contact elements 30 located thereabove. In some
applications, it is desirable to provide one fixed contact 23 in
any given switch area 26 at a level slightly below the level of the
remaining contacts. As the movable contacts are moved toward and
away from the fixed contacts, the lower fixed contact is the last
to make and the first to break the circuit and may be utilized in
computer input devices as a control function. The movable contact
elements 30 are preferably formed in a gang stamping 32 or
chemically etched on a sheet of tempered beryllium copper or other
material having a high degree of electrical conductivity. In the
gang stamping 32 thus formed, the contact element for each switch
unit is confined within a frame 34 which registers with the screen
of spacers 24 on the base panel 20 for support above the fixed
contact elements 22. The spacers 24 are shown constructed of
conductive material but as shown do not conduct current since they
rest on the insulated part of base panel 20 and are no part of the
keyboard circuit. Within this frame 34, one or more legs 36 extend
centrally inwardly to the movable contact element 30 to support the
same in yieldable suspension above the fixed contact element in
each switch cavity.
Two embodiments of the movable contact elements are illustrated in
FIGS. 3, 4, 6 and 7. As they are similar in construction, like
reference numerals will be utilized to designate like parts with
the prime (') designation utilized to distinguish the embodiment of
FIGS. 6 and 7.
As illustrated in FIGS. 3 and 4, the movable contact elements 30
are in the form of an annular flat ring 38 having spoke-like
fingers 39 extending radially inward therefrom toward the center.
In FIGS. 6 and 7, the movable contact element 30' is in the form of
a solid flat center 38' from which a plurality of fingers 39'
extend radially outward for yieldable contact with the fixed
contact elements 22.
In either form of movable contact 30, as shown in FIGS. 3 and 4 or
30' as shown in FIGS. 5 and 6, the spider-like legs 36 afford
yieldable suspension thereto. For such legs 36 are preferable
within each frame 34, each leg 36 having integral connection at its
base end 40 to one side of the frame 34 adjacent one corner
thereof. The legs 36 are separated from the adjacent right angled
side of the frame and extend approximately half way across the
square frame 34. Each leg 36 terminates in a hook-like bend 41 the
extreme end 42 of which is integrally connected to the contact
element 30 or 30' as the case may be. In the case of the spoked
center element 38 of FIGS. 3 and 4, the extreme ends 42 terminate
at approximately 90.degree. from the corner of the frame 34 where
the particular leg 36 is connected to the frame. In the case of the
solid centered contact 38' of FIGS. 6 and 7 having spider-like
fingers 39' for center type pressure, the extreme end 42 of each
leg 36 terminates at approximately a full 180.degree. relative to
the corner of the frame 34 where the particular leg 36 is connected
to the frame.
It is inherent in my copending application Ser. No. 860,861 that
when downward pressure is applied against either the open center
contact 38 or the solid center contact 38', the legs 36 associated
therewith are flexed while the center contacts and their spokes or
fingers move spirally downwardly perpendicular to the flat upper
surface of the printed circuit, i.e., rotating while moving
vertically within the switch zone 26 confining the same. In other
words, the fingers 39 turn or rotate while moving downwardly within
the switch zone 22. This rotating action is created by reason of
the hinge-like flexing action of the legs 36 from one plane into
another. As the annular flat ring-like member 38 on the inner ends
of the legs 36 is depressed, the distance between the ends of the
legs and their connection with the frame at the spacers changes
relative to the vertical, resulting in a spiralling descent of the
contact elements as they approach and finally make contact with the
fixed electrical conductors on the base panel. By this phenomenon a
wiping action of the fingers over the fixed contact occurs thereby
insuring a positive electrical contact.
Pressure against any one of the center portions 38 or 38', of the
movable contact elements 30 or 30' is applied through the resilient
cover 42 in FIGS. 2 and 5. The resilient cover 42 may be secured
adjacent the upper surface of the sheet of gang stamping 32. Thus
upon finger pressure against an identifying tab 44 formed on the
upper surface of the cover 42 the center contact 38 or 38' will
move vertically and spirally downwardly into wiping electrical
contact with the fixed contact element 22 below it.
To assure complete finger pressure and release thereof via the
resilient cover 42, the latter may be spaced slightly from the
yieldable stamping 32 which by its own resiliency will assume a
flat condition, spaced from the fixed contact element below. In
such case the resilient cover 42 is mounted on a second framework
of spacers 46 which are aligned perfectly above the lower spacer
24. In addition thereto the fingering tab 44 may be provided with a
downwardly projecting bead 48 for engaging the center 38 or 38' of
the movable contact element 30 or 30' as the case may be.
In either case, upon downward movement of the depending bead 48,
the radially extending arms or spokes 39, respectively, may flex
slightly upon engagement with the fixed contact element or elements
22 therebelow. Full pressure downwardly forces the contact elements
38 or 38' all the way down to the upper surface of the base panel
20 and the spoke-like fingers 39 or the fingers 39' will flex by
reason of their extreme ends engaging the fixed contact elements 22
on the base. This is an important feature of the present invention
because by this phenomenon a wiping action of the finger tips over
the fixed contacts occurs in addition to the previously-described
rotary wiping action.
Under extreme variations in temperature, the resilient cover 42 may
have a tendency to become too soft or too rigid. For this reason it
is sometimes necessary to reinforce the resilient cover 42 with
spring means, such as, a gang type stamped panel or so-called
stamping 50 of heat treated or tempered spring steel.
This spring steel stamped panel 50 is formed much the same as the
tempered beryllium copper sheet 32 for the movable contact elements
30 as previously explained. It may have the same configuration as
the sheet 32 in FIG. 4 or may utilize a configuration as shown in
my previously mentioned copending application.
As illustrated in FIGS. 2 and 5, the spring steel stamping 50 is
supported on the spacers 46. The resilient cover 44 may have
depending ribs 52 registerable with the spacers 44 and 24 for
support thereon. It will be noted that each ring-like center of the
spring steel stamping 50 is secured to the resilient cover 42 in
annular grooves 54 formed in the depending bead 48 axially below
each fingering tab 44 on the cover.
PREFERRED EMBODIMENT
Referring now to FIGS. 8, 9, and 10, a preferred construction of
the multiple switch assembly is shown. This preferred embodiment is
similar to that previously described and further includes a
plurality of individual push button type keys, modified flexible
contacts, return springs and a layer of resilient non-conductive
material to minimize contact bounce and to seal the switching zone
26a against contaminates. Consequently, like reference numerals
designated by lettered exponents are applied to like parts thereof
for the purposes of clarity.
Turning specifically to FIG. 8, the multiple switch assembly, in
its preferred embodiment, comprises a non-conductive base panel 20a
having a photographically printed circuit etched on its upper
surface, to provide a plurality of fixed contact elements 22a
thereon. The fixed contact areas are divided by a screen of spacers
24a into separate switch areas or zones 26a. Each of the contact
elements 22a may have independent electrical connections to one
side of an electrical circuit in a manner as previously described
in connection with FIGS. 1, 2, 5 and 12.
For convenience, the assembly may be mounted on a backing plate or
mounting board 56 with a sheet of insulating material 58 provided
to isolate the printed circuit board 20a from the backing plate
56.
The movable contact elements 30a, formed in a gang stamping 32a,
are mounted above the fixed contacts 22a and spaced slightly
therefrom by the spacer elements 24a. A thin sheet of resilient
insulating material such as, for example, neoprene rubber 60, is
placed over the movable contact members 30a. This layer has a
damping effect on the contacts thereby minimizing contact bounce as
the circuit is opened and closed. The layer 60 further effectively
seals the switching zone 26a and prevents contaminating materials
from entering therein. A second framework of spacers 46a placed
over the assembly are aligned with the lower spacers 24a to define
an opening above the switching area and support the return spring
assembly 50a. Lastly, the push button assembly or keyboard 62
carrying a plurality of independent keys 64 is mounted above the
switching zones. Individual plungers 66 connected at one end to the
keys 64 rest on their opposite end on the return springs 50a and
are supported for linear movement in a guide plate 68.
The construction of the modified movable contact elements 30a shown
in FIG. 10 is similar to that shown in FIG. 6. The movable contact
elements 30a are preferably formed in a gang stamping 32 or
chemically etched on a sheet of tempered beryllium copper or other
material having a high degree of electrical conductivity. In the
gang stamping 32 thus formed, a contact element for each switch
unit is confined within a frame 34a which registers with the
spacers 24a on the base panel 20a for support above the fixed
contact elements 22a. Within this frame 34a, one or more legs 36a
extend centrally inwardly to the solid center contact portion 38a
to support the same in yieldable suspension above the fixed contact
element in each switch cavity or area 26a as shown in FIG. 8. The
movable contact element 30 is in the form of a solid flat center
38a from which a plurality of fork-like contact fingers 39a extend
radially outwardly for yieldable contact with the fixed contact
elements 22 on the base panel. The legs 36a afford yieldable
suspension to the flat center 38a. Four such legs 36a are
preferable within each frame 34a. Each leg 36a is connected at its
base end 40a to one side of the frame 34a adjacent one corner
thereof. The legs 36a are separated from the adjacent right angle
side of the frame and extend across the square frame 34a to a point
just short of the adjacent leg 36a. Each leg terminates in a bend
41a the extreme end 42a of which is integrally connected to the
contact center 38a. The extreme end 42a of each leg 36a terminates
at approximately 135.degree. angle relative to the corner of the
frame 34 where the particular leg 36a is connected to the
frame.
When downward pressure is applied against the solid center contact
portion 38a, the legs 36a associated therewith are flexed while the
contact fingers move spirally downwardly perpendicular to the flat
upper surface of the printed circuit, i.e., turning while moving
vertically within the switch zone 26a confining the same. In other
words, the fingers 39a turn or rotate while moving downwardly
within the switch zone 26a. This rotating action is created by
reason of the hinge-like flexing action of the legs 36a from one
plane into another. As the annular flat ring-like member 38a on the
inner ends of the legs 36a is depressed, the distance between the
ends of the legs and their connection with the frame at the spacers
changes relative to the vertical, resulting in a spiralling descent
of the contact elements as they approach and finally make contact
with the fixed electrical conductors on the base panel. This is an
important feature of the present invention because by this
phenomenon a wiping action of the fingers over the fixed contact
occurs thereby insuring a positive electrical contact.
The return spring 50a for the push button assembly is illustrated
in detail in FIG. 9. The return springs are preferably heat treated
or tempered spring steel and are formed in much the same manner as
the movable contact elements 30 as previously explained. The sheet
of springs may be stamped or chemically etched in a manner
well-known to those skilled in the art. The individual springs 50a
are contained within a frame 70 conforming to the spacers 46a for
support thereon as illustrated in FIG. 8. The spring member is
formed within each frame 70. At its center an annular disk-shaped
member 72 is supported inside a central ring-like member 74 by a
plurality of legs 76. Each of the legs are integrally connected at
one end to the ring 74, spirally encompassing at least a portion of
the disk member 72 and are connected to the disk at their other end
approximately 180.degree. from their connection to the ring 74.
Each disk 72, then, is flexibly and yieldably supported within the
ring member 74.
The ring member itself is supported within the frame on at least a
pair of spiral-like legs 78. The legs are connected at one end 80
to opposite sides of the frame and extend completely around the
center ring member 74 where they are connected at their opposite
ends 82 to the ring member. The connection of the leg 78 to the
ring 74 is preferably at a point on the ring in line with the end
80 of the leg 78.
The spring member 50a may be formed with a slight depression 84 at
its center portion 72 within the ring member 74 as illustrated in
FIG. 8. This depression is arranged to be in alignment, when
assembled, with the center portion 38 of the movable contact
assembly 30 so that downward movement is transmitted directly to
the center portion thereof. The center ring 74 may be formed in an
upward direction with respect to the frame. This additional
formation of the spring member provides a means for controlling the
pre-travel, pre-load and over-travel of the push button and
switching means. In effect, by varying the spring formation, a
touch control for the push buttons can easily be provided.
The operation of the switch is similar to that illustrated in FIG.
2. As the key 64 is depressed, the corresponding downward movement
of the plunger 66 and spring member 50a is effected through the
opening 86 in the spacer 46a. As the center portion 72 of the
spring 58 contacts the resilient member 60, the downward force is
transmitted therethrough to the flat ring 38a of the movable switch
contacts. The contacts 39a are moved downwardly with rotary wiping
action until contact is made with the fixed contact elements 22a
and the circuit is completed. As the key is released, the spring
will return the plunger and its associated key to its original
position as the movable switch contacts are also moved upwardly to
their first position, that is, spaced apart from the fixed
contacts.
An alternate embodiment of the construction shown in FIG. 8 is
illustrated in FIG. 11. In this embodiment the insulating material
60a is provided with expanded portions or air pockets 88 positioned
on each of the movable contacts 38a. Downward movement of the
plunger transmitted through the air pocket 88 will cause the
contacts to move downwardly with the spiral, rotary wiping action
as previously described. As the key is released, the contacts will
return to their normal open or upward position.
In some applications, this embodiment may be utilized as a direct
replacement for the insulating material 60a shown in FIG. 8 to more
effectively eliminate contact bounce.
In other applications it may be desirable to eliminate the upper
spacers 46a and the return springs 50a of FIG. 8, having the key
plunger 66 acting directly on the air pockets 88 to move the
contacts downwardly. The elimination of component parts will result
in a more compact package together with a corresponding reduction
in unit cost.
From the foregoing, it will be appreciated that the multiple switch
construction of the present invention provides a simple form of
switching means which is inexpensive from the standpoint of
manufacture and involves a minimum number of parts by reason of
printed type circuitry and mass stamping or etching of switching
elements with the least effort in labor assembly. The switching
contacts thus formed and constructed result in relatively, flat,
plate-like switchbanks, keyboards, and the like, having a wide
application in any industry requiring momentary switching
functions.
While the preferred embodiments of this invention have been
illustrated in detail, it will be apparent to those skilled in the
art that many modifications thereof may be made without departing
from the concepts disclosed herein. Such modifications are to be
considered as included in the following claims, unless these claims
by their language expressly state otherwise.
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