U.S. patent number 3,808,384 [Application Number 05/334,345] was granted by the patent office on 1974-04-30 for pushbutton keyboard system.
This patent grant is currently assigned to Texas Instruments Incorporated. Invention is credited to Henry J. Boulanger.
United States Patent |
3,808,384 |
Boulanger |
April 30, 1974 |
PUSHBUTTON KEYBOARD SYSTEM
Abstract
A keyboard system in which a plurality of spaced sets of
conductive members including U and rivet shaped are arranged at a
surface of a support in electrical communication with conductive
paths on an opposite surface of the support. A plurality of
actuatable conductive elements, one for each set of conductive
members, are provided to establish bridging electrical connection
between conductive members of a set upon application of a
preselected deflecting force to the conductive elements. Two pole
embodiments are disclosed also employing rivet shaped and modified
U shaped conductive members.
Inventors: |
Boulanger; Henry J.
(Cumberland, RI) |
Assignee: |
Texas Instruments Incorporated
(Dallas, TX)
|
Family
ID: |
26845926 |
Appl.
No.: |
05/334,345 |
Filed: |
February 21, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
148503 |
Jun 1, 1971 |
3725907 |
|
|
|
Current U.S.
Class: |
200/5A; 200/275;
200/516; 341/34 |
Current CPC
Class: |
H01H
13/702 (20130101); H01H 13/7006 (20130101); G06C
7/08 (20130101); H01H 13/64 (20130101); H01H
2203/006 (20130101) |
Current International
Class: |
H01H
13/64 (20060101); H01H 13/70 (20060101); H01H
13/702 (20060101); G06C 7/08 (20060101); G06C
7/00 (20060101); H01H 13/50 (20060101); H01h
013/52 (); H04q 003/00 () |
Field of
Search: |
;200/1R,5R,5A,11R,11G,11H,11J,11K,16D,159B,166BH ;178/17C ;179/9K
;340/365A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scott; James R.
Attorney, Agent or Firm: Haug; John A. Connors, Jr.; Edward
J. McAndrews; James P.
Parent Case Text
This is a continuation-in-part of application Ser. No. 148,503,
filed June 1, 1971 now U.S. Pat. No. 3,725,907. The present
invention relates generally to keyboard systems and more
particularly is directed to an improved two pole pushbutton
keyboard system for establishing electrical connections in response
to actuation.
Claims
1. A selectively energizable keyboard system comprising an
electrically insulating support member having a generally planar
first surface on which a plurality of conductive paths are disposed
arranged in a preselected pattern adapted to transmit electrical
information in response to selective energization of portions of
said paths,
a plurality of selectively actuatable conductive elements adjacent
a second opposite surface of said support member said conductive
elements each being dish shaped having a single smooth surface
contained within its outer peripheral margin, the surface being
convex in a first configuration but movable to concave in a second
configuration upon receiving a preselected deflecting force,
a set of conductive contact members associated with each said
actuatable conductive element, at least one of said sets comprising
a pair of conductive contact members, said contact members being
arranged at said second surface of said support member in
electrical communication with preselected portions of said
paths,
conductive support means disposed at said second surface of said
support member, said support means supporting each said selectively
actuatable conductive member in overlying relation to its said
associated set of conductive contact members with the said set of
contact members generally centrally located beneath its said
conductive element in continuous electrical engagement with said
conductive support means and in selective disengagement with said
set of conductive contact members, said conductive elements being
adapted to be deflected into a position of engagement with said set
of conductive contact members so as to establish an electrical
connection between said conductive support means and said
respective set of conductive contact members and said respective
preselected portions of said paths in response to the application
of a preselected deflecting
2. A system in accordance with claim 1 wherein means are provided
for applying the preselected deflecting force to said conductive
elements, including a plurality of pushbutton members adapted to be
manually actuated to apply the deflecting force to said conductive
elements to effect deflection thereof into a position of engagement
with said conductive contact member, each of said pushbutton
members having a force applying surface in registration with a said
conductive element and another surface adapted to be symbolized in
a manner indicative of the electrical information transmitted in
response to the energization of said
3. A system in accordance with claim 1 wherein said conductive
support means comprises a sheet of electrically conductive
material, apertures are formed in the sheet to encompass each said
set of conductive contact members, the said apertures being smaller
than the said conductive elements so that each said conductive
element is supported on the sheet in continuous electrical
engagement therewith and in selective disengagement
4. A system in accordance with claim 1 wherein the said set of
conductive contact members project outwardly a first preselected
distance from said second surface of said insulating support and
said conductive support means project outwardly a second
preselected distance more than said first preselected distance from
said second surface of said insulating support
5. A system in accordance with claim 4 wherein said conductive
elements are each of a generally circular configuration having
marginal edge portions supported on the conductive support means
and a generally central portion maintained in selective
disengagement with and adapted to be deflected
6. A system in accordance with claim 5 wherein a relatively thin,
flexible, insulative, force-transmittive overlayer is disposed on
said insulating support member in overlying relationship with
respect to said conductive elements so as to maintain said
conductive elements in a position
7. A system in accordance with claim 1 wherein the said of
conductive contact members having a pair of conductive contact
members comprise
8. A system in accordance with claim 7 wherein said conductive
elements are each a generally circular configuration having a
marginal boundary supported on said conductive support means and
having a generally central portion spaced from and maintained in
selective disengagement with said headed rivets and adapted to be
deflected into engagement therewith in response to the application
of the preselected deflecting force to said conductive element
thereby establishing a bridging electrical contact between said
conductive support means and said set of headed rivets so as
9. A system in accordance with claim 1 wherein said conductive
support means comprises a plurality of spaced apart sets of
conductive support members arranged in a preselected configuration
at said second surface of said support member in electrical
communication with preselected portions
10. A system in accordance with claim 9 wherein each of said sets
of conductive support members includes a plurality of spaced first
metallic members extending through said insulating support member
and terminating in electrical contact with preselected portions of
said conductive paths.
11. A system in accordance with claim 9 wherein each set of
conductive support members comprises a pair of staples secured to
said insulating
12. A system in accordance with claim 11 wherein the said sets of
conductive contact members having a pair of conductive contact
members comprise generally L-shaped metallic wire members of a
smaller guage than
13. A system in accordance with claim 1 wherein the sets of
conductive contact members having a pair of conductive contact
members comprise a pair of generally L-shaped metallic wire
members, each L-shaped member comprising first and second legs, the
first legs of each extending through apertures in the support
member and terminating in electrical contact with
14. A system in accordance with claim 13 wherein the second legs of
the
15. A system in accordance with claim 13 wherein the second legs of
the
16. A keyboard system comprising an electrically insulative support
member having a generally planar surface and having apertures
therein,
a plurality of selectively deflectable conductive elements,
a pair of spaced wire staples having a first guage provided for
each said conductive element, each said staple having legs joined
to a bight portion, the said legs extending through selected ones
of said apertures in said support member with each said bight
portion contiguous to said planar surface, said conductive elements
supported on its respective said pair,
a pair of conductive contact members disposed between each said
pair of wire staples, each said conductive contact member comprises
a generally L-shaped metallic wire member of a second smaller
guage, each said L-shaped wire member having a first and a second
leg, the said first leg extending through a selected said aperture
in the said support member and the said second leg lying along the
said planar surface,
and electrical circuit means connected to said staples and said
L-shaped wire members, deflection of any said conductive element
bridging its respective said pair of wire staples and its
respective pair of conductive contact members.
Description
In recent years numerous types of keyboard systems have been
developed for use in transmitting coded electrical information for
incorporation in various types of business machines such as
electronic calculators. Typically such keyboard systems utilize
pushbutton members appropriately symbolized in a manner indicative
of a numeric or mathematical function generated in response to
depression of the pushbutton member to establish electrical
connections between various conductive paths and/or various circuit
elements coupled to the system in order to achieve a desired
function. However, particularly as the cost of associated equipment
has decreased dramatically in recent years coupled with an increase
in the use and availability of various devices incorporating such
systems the need has arisen for extremely inexpensive readily
manufacturable keyboard systems which may be economically and
accurately produced on a mass production basis with a high degree
of accurate repeatability. For example, the need for miniaturized
electronic calculators, units for addressing computer systems,
credit cards verifiers, etc. which necessarily require various
types of keyboard arrangements has enormously increased in recent
years requiring the provision of inexpensive and extremely durable
keyboard systems which may be manufactured in a simple and
economical manner on a relatively large volume basis. Particularly,
in the computer field the need for durable, inexpensive keyboard
systems which can accurately address electrical information either
directly to a system or through a remote terminal or the like,
while occupying a minimal amount of space, has become increasingly
urgent.
Accordingly, it is an object of the present invention to provide an
improved keyboard system adapted for selectively establishing
electrical interconnections in response to mechanical
actuation.
It is another object of the present invention to provide an
improved pushbutton keyboard system in which actuation of
individual pushbutton members establishes positive electrical
interconnections for transmitting electrical information.
It is a further object of the present invention to provide an
improved miniaturized pushbutton keyboard system which is
relatively rugged and durable and which is extremely economical to
fabricate on a mass production basis, and which is adapted for
incorporation in various devices, such as electronic calculators,
computer systems, etc.
Various additional objects and advantages of the present invention
will become readily apparent from the following detailed
description and accompanying drawings wherein:
FIG. 1 is an exploded perspective view illustrating a preferred
embodiment of a keyboard system in accordance with the present
invention;
FIG. 2 is a vertical sectional view through the keyboard system
illustrated in FIG. 1;
FIG. 3 is a partial plan view of the underside of the system
illustrated in FIG. 2;
FIG. 4 is an exploded perspective view of an alternative embodiment
of a keyboard system similar to that illustrated in FIG. 1;
FIG. 5 is a vertical sectional view through the keyboard system
illustrated in FIG. 4;
FIG. 6 is a plan view of the underside of the system illustrated in
FIG. 5;
FIG. 7 is a perspective view illustrating a typical variety of
electronic calculator incorporating a keyboard system such as that
illustrated in the preceding embodiments.
FIG. 8a is a broken away perspective view showing how a centrally
placed U-shaped conductive member can be modified to effect a two
pole arrangement useful in the keyboard system according to the
present invention;
FIG. 8b is a view similar to FIG. 8a but showing a completed two
pole arrangement;
FIG. 9 is a schematic circuit diagram of a two pole switch
arrangement as shown in FIG. 8;
FIG. 10 is a broken away perspective view of another two pole
switch similar to FIG. 8b;
FIG. 11 is a broken away perspective view of yet another two pole
switch; and
FIG. 12 is a broken away perspective view of another two pole
switch.
Referring generally to the drawings, wherein corresponding elements
in the various views are indicated by common reference numerals,
and in particular initially to FIGS. 1-3, a keyboard system 10 in
accordance with the present invention is illustrated. The system
generally includes a non-conductive or insulating support member 12
having a generally planar first surface 14 on which a plurality of
conductive paths 16 are disposed and arranged in a preselected
pattern for transmitting electrical information in response to
selective interconnection of portions thereof. At a second opposite
surface 18 of the insulating support member 12 a plurality of sets
20 of conductive support members are provided which are arranged in
a preselected configuration in electrical communication with first
preselected portions 16a of the conductive paths 16. Associated
with each of the conductive support members are conductive contact
members 22 similarly arranged at the second surface 18 of the
insulating supporting layer in electrically isolated relationship
with the conductive support members and in electrical communication
with second preselected portions 16b of the conductive paths 16. A
plurality of selectively actuatable conductive elements 24 are also
arranged adjacent the second surface 18 of the insulating support
layer and are respectively supported by and maintained in
continuous electrical contact with each of the sets 20 of
conductive support members and in selective disengagement with the
associated conductive contact members 22. The conductive elements
24 are adapted to be deflected into a position of engagement with
the conductive contact members 22 in response to the application of
a preselected deflecting force thereto so as to establish a
bridging electrical contact between one of the sets 20 of
conductive support members and its associated conductive contact
member 22, thereby electrically connecting the first and second
preselected portions 16a, 16b of the conductive paths 16. Actuation
of the conductive elements 24 so as to effect the establishment of
the aforementioned bridging electrical connection may be effected
in various ways, but in the illustrated embodiment it is
accomplished by the provision of a plurality of manually actuatable
pushbutton members 26 which are carried in a suitable casing 28
supported adjacent the second surface 18 of the insulating support
member 12 whereby the application of a preselected deflecting force
to the conductive elements 24 is effected by actuation of a
selected pushbutton member 26 by the application of a mechanical
force thereto such as through the fingertips of an operator. As a
result of manual actuation of a selected pushbutton member 26 the
preselected deflecting force is applied to the conductive element
to effect deflection thereof into a position of engagement with the
conductive contact member 22, thereby establishing the bridging
electrical connection between the set of conductive support members
20 and the conductive contact member 22 and hence establishing an
electrical connection between the first and second preselected
portions 16a, 16b respectively of the conductive paths 16. In
addition, if desired, a suitable device such as an integrated
circuit shown in phantom and indicated generally by the reference
numeral 30 may be carried by the insulating support member 12 and
suitably connected to selected portions of the conductive paths 16
so as to process the signals established by the interconnection of
various portions of the conductive paths in response to the
establishment of the bridging electrical connections. Similarly, if
desired, a power supply (not shown) may be also carried on the
support member 12 to provide a self-contained composite unit, or an
external source of power may be utilized as the sole source of
power or as an additional or alternative energy source.
More particularly, the insulating support member 12 is fabricated
of a relatively rigid, non-conductive material which is adapted to
provide support for the keyboard system, as well as associated
electronic circuitry, power supplied, display means, etc. when the
unit is to be incorporated in an electronic calculator system, a
computer input system, etc. In this regard the member 12 may be
fabricated of a suitable, relatively rigid, insulation material
such as epoxy bonded glass cloth generally sold under the trade
description G-10 by the Formica Company. The material may have a
thickness of approximately 1/16th inch which has been generally
found sufficient to provide adequate mechanical strength for a
miniaturized device of this nature. As previously mentioned, the
conductive paths 16 including the first and second preselected
portions thereof 16a, 16b respectively are arranged in a desired
pattern at the first surface 14 (the underside of the support
member 12, as illustrated in FIG. 2) in order to permit the
transmission of electrical information in response to selective
interconnection of various portions of the conductive paths upon
the establishment of the bridging electrical connections. The
pattern of conductive paths may be deposited on the surface 14 of
the support layer utilizing conventional printed circuit art
techniques, such as masking, etching, engraving etc. In addition, a
plurality of apertures 32 are provided extending through the
thickness of the support member 12 between the first surface 14 and
the second surface 18 thereof so as to permit the selective
establishment of electrical communication between the conductive
paths at the surface 14 and the conductive support members 20 and
contact members 22 arranged at the opposite surface 18. In this
regard the apertures may be provided prior to or subsequent to the
deposition of the conductive paths, thereby providing a prepunched
support board prepared for further fabrication operations.
In the illustrated embodiment the sets of conductive support
members 20 are arranged to define a plurality of spaced sets of
pairs of generally U-shaped, conductive members preferably
comprising staples arranged at the surface 18 of the support layer
12. Such an arrangement has been found to be extremely advantageous
in achieving the enhanced ease of fabrication of the system since
the staples may be readily inserted through the apertures 32 in the
pre-punched support member 12 utilizing suitable high-speed
automated stapling equipment. Similarly, electrical communication
may be conveniently established between these staples and selected
portions of the conductive paths 16. As shown, the staples 20 each
include a main body portion 34 of a generally looped configuration
terminating in a pair of legs 36 which are received within the
apertures 32 in the support layer 12. The apertures 32 are of a
size sufficient to accommodate the legs 36 in a close-fitting
relationship, while the outer ends of the legs are crimped against
the surface 14 and are in contact with the selected portions of the
conductive paths 16, such as the first preselected portions 16a.
Consequently, a rigid mechanical connection is established and the
electrical contact may be improved by soldering the crimped
portions of the legs into position. In addition, as shown, the main
body portion 34 of each of the staples comprising the plurality of
sets of support members projects a first preselected distance
outwardly from the surface 18 of the support member 12 so as to
define conductive support areas spaced from the surface 18 for
carrying the conductive element 24. Similarly, the associated
conductive contact members 22 are also illustrated as generally
U-shaped conductive members, preferably comprising staples each
having a main body portion 38 which terminates in a pair of legs 40
which project through apertures 42 extending through the thickness
of the support member 12 similarly to the apertures 32, but
providing communication with other portions of the conductive paths
16, such as the second preselected portions 16b. The legs 40 extend
through the apertures 42 with the outer ends thereof being crimped
against the surface 14 of the support layer 12 preferably in
contact with other portions of the conductive paths 16, such as the
second preselected portions 16b. The apertures 42 are of a size
sufficient to accommodate the legs 40 of the staple 22 while the
outer ends of the legs 40 are crimped against the surface 14 in
contact with the second preselected portions 16b of the conductive
paths to rigidly secure the staple to the member 12. In addition,
the outer ends of the legs 40 crimped in position against the
second preselected portions 16b of the conductive paths 16 may be
soldered in this position to provide an improved electrical contact
as shown. One of the contact staples 22 is arranged intermediate
each of the pairs of support staples 20 and may be of a slightly
smaller gauge such that its main body portion 38 projects outwardly
from the surface 18 a second preselected distance different than
the first preselected distance which the body portion 34 of the
support staples 20 projects from the surface so as to facilitate
maintenance of selective disengagement between the conductive
elements 24 and the contact staples 22, as will be subsequently
explained. The conductive support staples 20 and the conductive
contact staples may be fabricated of various materials and material
combinations depending upon the properties desired. For example, in
one preferred embodiment the staples are fabricated of gold-plated
nickel wire in order to provide a relatively non-reactive material
having good surface contact properties. As other examples, the
staples may be fabricated of gold-glated stainless with a flash of
nickel intermediate the stainless steel core and the gold plating,
or of beryllium copper.
The conductive elements 24 preferably comprise a plurality of
generally circular, disc shaped elements formed of a segment of a
hollow body or dished shape having a double curved outer surface
such as a segment of an oblique spheroid and are each illustrated
as including a generally convex surface of curvature when in an
unactuated or rest state which is in facing relationship with the
pushbutton members 26. The element 24 is selected such that is has
an overcenter position when its central portion is subjected to a
preselected deflecting force while automatically returning to its
original position upon removal of the force, whereby the element is
provided with a memory function. Of course, segments of other
hollow bodies having double curved surfaces may be utilized in
providing the conductive elements. The element 24 may be arranged
such that it undergoes a snap-action deflection into its overcenter
position in order to establish the aforementioned bridging
electrical contact. In this regard referring particularly to FIG.
2, one of the elements indicated by the numeral 24a is shown in its
overcenter position in response to actuation by a depressed
pushbutton member indicated by reference numeral 26a. However, it
should be noted that in certain instances the central portion of
conductive element 24 may be sufficiently closely spaced to the
contact staple 22 that the element 24 need not be completely
deflected into its overcenter position in order to contact the
staple 22 for establishing the requisite bridging contact. Thus,
upon application of the preselected deflecting force to the central
portion of the conductive element 24 in response to actuation or
depression of the pushbutton member 26 the element 24 is caused to
undergo a snap-action deflection into its overcenter position. In
addition, as a result of this snap-action deflection a tactile
feed-back is provided which may be sensed in the finger tips of the
operator actuating a particular pushbutton. Furthermore, an audible
acknowledgement of deflection may accompany the snap-action
deflection which may be further sensed by the operator as an
additional indication of actuation of a pushbutton member to
transmit a desired electrical signal. The conductive elements 24
preferably comprise gold-plated stainless steel discs and in one
preferred embodiment may be fabricated of AISI (American Iron and
Steel Institute) Type 302 Stainless Steel, which comprises by
weight approximately 0.15 percent carbon, 2.00 percent (max.)
manganese, 1.00 (max.) silicon, 17 to 19 percent chromium, 8 to 10
percent nickel and the balance iron, with a thin gold plating over
its exposed contact surfaces.
Each of the conductive elements 24 is maintained in axial registry
with the conductive contact staple 22 associated with each of the
sets of support staples 20 with the central portion thereof spaced
from the contact staple 22. The marginal edges of the conductive
elements 24 are supported on the main body portions 34 of the
support staples 20 of each set such that the conductive element 24
is in continuous electrical contact therewith and hence with the
first preselected portions 16a of the conductive paths 16.
Similarly, the central portion of the conductive elements 24 which
are in registry with the main body portions 38 of the contact
staples 22 remain in selective disengagement with the contact
staples until deflected by actuation of a pushbutton member 26,
whereupon the bridging electrical connection is established between
a set of conductive support staples 20 and its associated
conductive contact staple 22 and hence between the first and second
preselected portions 16a, 16b of the conductive path 16.
In order to further support each of the conductive elements 24 and
provide lateral restraint therefor a carrier sheet of insulating
material 44 is disposed adjacent the surface 18 of the support
member 12 overlying the plurality of sets of conductive support
staples 20 and associated conductive contact staples 22. The sheet
44 includes a plurality of apertures 46 which are of a size
sufficient to accommodate the conductive elements 24 therein and
arranged in registry with the plurality of sets of conductive
support staples 20 and the associated conductive contact staples
22. More particularly, the conductive elements 24 are disposed
within the apertures 46, which are of a size slightly larger than
the spacing intermediate the staples comprising each of the sets of
conductive support staples. Accordingly the sheet 44 may be
maintained essentially in abuttment with the surface 18 of the
support member 12 with the main body portions 34 of the conductive
support staples 20 which support the elements 24 extending slightly
into the apertures 46. The conductive elements 24 are arranged
within the apertures 46 and have opposed marginal portions resting
on the main body portions 34 of the conductive support staples 20.
Thus, support, as well as lateral restraint for the conductive
elements 24 is provided. In addition, as may be noted, particularly
in FIG. 1, each of the apertures 46 is of a preselected shape
including a pair of opposed parallel walls 46a which are of a
generally straight-line configuration, these generally
straight-line wall portions being arranged to bound the main body
portions 34 of the conductive support staples 20 which extend into
the apertures 46. The other pair of opposed wall portions 46b of
each of the apertures 46 are arranged in a generally curvilinear
configuration curving outwardly from the center of the apertures 46
so as to more efficiently accommodate the generally circular
conductive elements or discs 24. In this regard by virtue of
providing the apertures 46 having a shape as illustrated certain
advantages are achieved in that the overall space occupied by the
apertures is minimized, since only one of the two dimensions of the
apertures are increased while the other dimension is minimized,
thereby maximizing the amount of material which remains to define
the layer 44 in order to enhance its structural strength and
rigidity. This is advantageous in view of the small size of the
layer 44 and the large number of apertures which are employed. The
sheet 44 may be fabricated of a suitable non-conductive material
such as a suitable glass cloth reinforced epoxy. In addition, the
marginal portions of the sheet 44 which extend beyond the sets of
support staples 20 at opposed sides of the support board 12
preferably are bonded or sealed to the marginal portions of support
member 12 so as to facilitate the formation of an environmentally
sealed unit.
In certain instances, it has been found desirable to further
restrain the conductive elements 24 in their respective positions
by providing a relatively thin, flexible sheet or film of an
insulating force transmitting over-layer sheet or film 48, as
shown, which is arranged intermediate the sheet 44 and the casing
28 which supports the pushbutton members 26. The over-layer 48 may
comprise a material, such as polyethylene, terephthalate, commonly
sold under the trade name Mylar, and may be suitable bonded or
sealed to the exposed surface of the layer 44 and hence functions
to prevent the conductive elements 24 from inadvertently being
removed or falling from their desired positions within the
apertures 46, as well as completing an environmental seal for the
unit.
The pushbutton members 26 are each appropriately symbolized at
their outer exposed surfaces in a manner indicative of the
electronic function associated with actuation of a selected
pushbutton member which establishes the requisite bridging
electrical connection between the conductive support staples 20 and
the conductive contact staple 22 and hence between the first and
second preselected portions 16a, 16b of the conductive paths 16. In
addition, each of the pushbutton members includes an opposed
protruding surface portion 50 which depends from the main body
thereof and is maintained in abuttment with the generally central
region of the conductive element 24 and is adapted to apply the
requisite deflecting force thereto in response to actuation of the
pushbutton member. Each of the pushbutton members 26 is preferably
fabricated of a relatively rigid non-conductive plastic material,
and is supportingly carried within the support casing 28 which
includes a plurality of slots 51 for accommodating the body of the
members 26. The casing 28 may be similarly fabricated of a suitable
rigid, non-conductive plastic material, or the like. In this regard
each of the pushbutton members 26 include a flanged portion 52
which integrally extends from one pair of opposed lower edge
surfaces thereof. These flange portions 52 are adapted to be
received within accommodating channels or slots 54 in the casing 28
when the members 26 are positioned in the casing 28 to preclude
lateral motion of the pushbutton elements 26 within the casing,
while permitting movement of the pushbutton members normal to the
planar surface of the casing 28 upon actuation thereof. In
addition, the casing 28 includes a pair of depending flange members
56 the spacing therebetween being of a size sufficient to
accommodate the marginal edge portions 12a, 12b of the support
member 12 if it is desired to provide an environmental seal between
these marginal edge portions 12a, 12b and the inner surfaces of the
flange members 56, when the casing 28 is positioned in abuttment
with the overlayer sheet 48 with the pushbutton members aligned
with the respective conductive elements 24. Thus, in operation the
pushbutton members are precluded from lateral movement within the
casing but are permitted to be moved from a retracted to an
actuating position in response to application of a mechanical force
to the exposed surfaces thereof so as to effect deflection of an
associated conductive element 24. Accordingly, upon actuation of a
selected pushbutton member the conductive element 24 is caused to
execute a snap-action deflection into its over-center position in
which it is in engagement with one of the associated contact
staples 22, as well as with the set of supporting staples 20,
establishing a bridging electrical contact between the contact
staple 22 and the set of support staples 20 associated
therewith.
Referring now to FIGS. 4-6 an alternate embodiment of a keyboard
system similar to that illustrated in FIGS. 1-3 is shown in which a
modified arrangement for carrying the conductive elements is
provided. More particularly, in this embodiment a support member of
insulating material similar to the support member 12 is provided
having a preselected pattern of conductive paths 62 arranged at a
first surface 64 thereof while a plurality of sets of conductive
support members 66 are arranged at a second opposed surface 68 of
the board with an associated conductive contact member 70 being
provided associated with each of the sets of conductive support
members spaced from and electrically isolated from the set of
support members. The conductive support members 66 are adapted to
be disposed in cooperating apertures 72 which are provided
extending through the thickness of the support board 60 between the
first and second surfaces 64, 68 so as to permit electrical
communication to be established between each set of conductive
support members 66 and first preselected portions 62a of the
conductive paths 62, when these conductive support members are
inserted within the apertures 72 while a plurality of additional
apertures 74 similarly extend through the thickness of the support
member 60 for accommodating the associated conductive contact
members 70, the apertures 74 permitting electrical communication to
be established between the conductive contact members 70 and second
preselected portions 62b of the conductive paths 62, when the
conductive contact members 70 are inserted within the respective
apertures. Each of the sets of conductive support members 66 is
adapted to define a generally planar support area for supportingly
receiving a conductive element 76 similar to the conductive element
24. The conductive element 76 is supported in continuous electrical
contact with the set of support member 66 and hence in contact with
the first preselected portions 62a of the conductive paths 62. In
addition, the conductive element 76 remains in selective
disengagement with the associated conductive contact member 70 and
accordingly, each set of support members remains electrically
isolated from its associated contact member 70 until deflection of
the conductive element 76 is effected. Such deflection is
accomplished in a manner similar to that described in connection
with the preceding embodiment in response to the application of a
preselected deflecting force to the conductive element 76 to
establish engagement between the conductive element 76 and the
conductive contact member 70, thereby establishing a bridging
electrical contact between the set of conductive support members 66
and the conductive contact member 70 and hence between the first
and preselected portions 62a, 62b of the conductive paths 62. The
application of the preselected deflecting force to the conductive
element 76 is again accomplished by the provision of a plurality of
pushbutton members 78 maintained in registry with the respective
conductive elements 76 such that actuation or depression of a
pushbutton member 78 is effective to cause deflection of a
conductive element in order to cause it to engage its associated
conductive contact member thereby establishing the requisite
bridging electrical contact. The pushbutton members 78 are
similarly carried within a suitable support casing 80 which
includes a plurality of slots 82 for receiving the body of the
pushbutton members 78 therein, the pushbutton members being movable
from a retracted to an actuating position in response to the
application of a mechanical force to the exposed surfaces thereof,
such as by manual actuation.
As previously mentioned, in accordance with an important advantage
of the present invention a keyboard system is provided which is
particularly suitable for fabrication by rapid, accurate, and
inexpensive mass production techniques. The embodiment illustrated
in FIGS. 4-6 similarly provides such advantages in that the support
board 60 may be similarly provided in a prepunched configuration
including the apertures 72, 74 for accommodating the conductive
support members and the conductive contact members, while a desired
pattern of conductive paths may be deposited on the surface 64
thereof utilizing conventional printed circuit art techniques to
permit the selected electrical connections to be made between
respective portions of the conductive paths. However, rather than
employing staples, as in the preceding embodiment each of the sets
of conductive support members 66 preferably comprises a plurality
of collared rivets each of which includes a shank 82 and a flanged
collar 84 with the shank adapted to be inserted in the aperture 72
while the collar 84 rests against the surface 68 of the support
board, a portion of the shank projecting outwardly therefrom and
the opposite end 86 of the shank is crimped against the surface 64
of the support member 60 in electrical contact with the first
preselected portions 62a of the conductive path 62, thereby
mechanically restraining the rivet in position with respect to the
support member and the conductive path 62. In addition, the crimped
end 86 may be soldered in position to assure a good electrical
contact with the first preselected conductive path 62a. In the
illustrated embodiment each set 66 includes four of the previously
described rivets arranged to define a generally enclosed area with
the flanged collar portions 84 of each of the rivets defining a
generally planar support area for the conductive element 76. It
should be noted that a lesser or greater number of rivets, of
course, may be utilized. In addition, the associated conductive
contact member 70 is arranged generally centrally within the area
defined by the four rivets 66 and preferably comprises a headed
rivet including a shank portion 88 which is disposed within the
aperture 74 with one end 90 being crimped against the surface 64 of
the support board 60 as shown while its opposite end terminates in
a head 92 of a larger diameter than the aperture 74 such that the
rivet 70 is mechanically restrained with respect to the support
member 60, subsequent to the crimping of its end 90 against the
surface 64. The crimped end 90 is in electrical contact with the
second preselected conductive path 62b and similarly may be
soldered in position to assure a good electrical contact therewith.
In addition, as shown the head 92 of the rivet 70 may be displaced
outwardly from the surface 68 of the support member 60 a lesser
distance than the collar 84 of the support rivets 66 such that the
central portion of the conductive element 76 may be maintained in
selective disengagement therewith, as will now be explained in
detail.
More particularly, the conductive elements 76 are generally similar
to the elements 24, as described in connection with the embodiment
illustrated in FIGS. 1-3. The element 76 is arranged such that it
similarly undergoes deflection movement into its overcenter
position in order to establish the aforementioned bridging
electrical contact between the set of support rivets 66 and the
contact rivet 70 and hence between the first and second preselected
portions 62a, 62b of the conductive paths. In this regard the
marginal portions of the element 76 are supported by and rest upon
the flanged collar portion 84 of the support rivets 66 such that
the element 76 is maintained in constant electrical contact with
the set of support rivets 66 while its central portion remains in
selective disengagement with the head 92 of the contact rivet 70.
Upon application of a preselected deflecting force to the central
portion of the conductive element 76 in response to actuation or
depression of the selected pushbutton member 78 the element 76 is
caused to undergo a snap-action deflection into its overcenter
position and engages the head 92 of the contact rivet 70 thereby
establishing an abrupt, instantaneous and positive bridging
electrical contact between the support rivets 66 and the contact
rivet 70 and hence between the first and second preselected
portions 62a, 62b of the conductive paths 62. In addition,
similarly to the preceding embodiment, as a result of this
snap-action deflection a tactile feed-back is provided which may be
sensed in the finger tips of the operator actuating a particular
push-button, and an audible acknowledgement of deflection may
accompany the snap-action deflection and may be further sensed by
the operator as an additional indication of actuation of a
pushbutton member to transmit a desired electrical signal.
In order to further aid in maintaining the elements 76 in position
as well as to facilitate the formation of an environmental seal, it
has been found advantageous in certain instances to provide an
overlayer 94 of a flexible force transmitting material arranged
intermediate the pushbutton members 78 and the conductive elements
76. In this regard lateral movement of the conductive elements 76
is precluded by virtue of the disposition of the elements 76 within
the area defined by each of the sets of support rivets 66 resting
on the flanged collar portions 84, with the marginal edges of the
conductive elements 76 being laterally restrained by the portions
of the shanks 82 which project outwardly beyond the collars 84.
However, in order to prevent the elements 76 from being
inadvertently removed from or falling from the unit the overlayer
94 may be provided, as shown, and may be suitably bonded to the
marginal edge portions of the support board 60 to form an
environmental seal. The overlayer 94 may be fabricated of a strong,
flexible, thin insulation material, such as polyethylene
terephthalate, commonly sold under the trade name Mylar.
As previously mentioned, the pushbutton elements 78 are suitably
carried within the slots 82 in the casing 80 and as shown have
outer exposed surfaces which are appropriately symbolized in
accordance with the electrical information which is to be
transmitted in response to actuation thereof. In addition, a
generally centrally located protruding member 96 extends from the
opposed surfaces of each of the pushbutton members and is arranged
in axial registry with the central portions of each of the
conductive elements 76 so as to apply the preselective deflecting
force thereto in response to actuation or depression of the
pushbutton members 78. A pushbutton member 78a is illustrated in
FIG. 5 in its depressed or actuated condition to show the
establishment of the bridging electrical contact between the set of
conductive support rivets 66 and the conductive contact rivet 70,
whereby the requisite bridging electrical contact is established
between selected portions of the conductive paths 62. Each of the
pushbutton members 78, similar to the preceding embodiment, also
may include a pair of opposed flanges 97 which are adapted to be
received in cooperating channels 98 in the wall of the slots 82 in
the casing to provide improved lateral support for the pushbutton
member 76. The casing 80 also preferably includes a pair of
depending flange portions 99 extending along its longitudinal edges
spaced apart a distance slightly greater than the lateral dimension
of the support member 60 so that the inner portions of the flanges
99 may be sealed to the marginal edges of the support member 60 if
it is desired to provide an environmentally sealed unit. The casing
80 as well as the pushbutton members 78 may be fabricated of a
suitable insulating plastic material.
In operation it may be seen that similarly to the embodiment
illustrated in FIGS. 1-3 the actuation or depression of a selected
pushbutton member 78 effects deflection of its associated
conductive element 76 so as to effect the establishment of the
bridging electrical contact between the support rivets 66 and the
contact rivet 70 and hence between the first and second preselected
portion 62a, 62b of the conductive paths 62 so as to permit the
transmission of an appropriate electrical signal. In addition, as
illustrated in FIGS. 4 and 6, if desired, suitable semiconductor
devices or the like illustrated in phantom as a dual-in-line
package integrated circuit 100 may be provided with its lead
members 102 extending through suitable apertures 104 in the support
board 60 and maintained in contact with requisite portions of the
conductive paths 62 to as to selective couple the various circuit
elements thereof (not shown) to the paths 62 in order to process
the electronic information being transmitted upon interconnection
of selected portions of the conductive paths. Similarly, if
desired, a suitable power supply means (not shown) may be also
mounted on the support member 60.
Referring to the FIG. 7 embodiment a composite unit indicated
generally by the reference numeral 104 is illustrated, including a
plurality of pushbutton members 106 supported within a casing 108
which is mounted in overlying relationship with a support board 110
which may include conductive support areas, conductive contact
areas, conductive elements, conductive paths etc., all as shown and
described in the preceding embodiments. In addition, the unit 104
includes a visual display window 112 so as to provide a visual
indication of operation of the unit when it is being utilized as an
electronic calculator, for example, as an input to a computer
system, etc. Similarly, if desired, the unit 104 may include a
suitable print out mechanism to provide a permanent record, if
desired.
In certain applications it is desirable to provide multipole
switching for some or all of the keys. FIGS. 8a - 12 show several
embodiments which provide this structure. Thus as seen in FIGS. 8a
and 8b the FIG. 1-3 embodiment can be modified by cutting the
looped or bight portion of conductive contact member 22 to form a
pair of generally L-shaped members having first and second legs and
bending the severed leg 23, 25 either in the same direction or in
opposite directions as indicated in dashed lines in FIG. 8a and
solid lines in FIG. 8b. The outer legs of contact members 23, 25
are electrically connected as by crimping and soldering to two
separate conductive portions of conductive paths 16. Thus upon
application of a preselected deflecting force to the central
portion of a conductive element 24 in response to actuation or
depression of the selected pushbutton member 26 the element 24 is
caused to undergo a snap-action deflection into its overcenter
position and engages both contact members 23, 25 thereby
establishing an abrupt, instantaneous and positive bridging
electrical contact between the set of support members 34 and the
two pole contact members 23, 25 and hence between a first
preselected portion of conductive paths 16 and the other two
separate portions thereof. As seen schematically in FIG. 9, A
represents the two support members 34 while B and B' represent
contact members 23 and 25 respectively. Deflection of element 24
into bridging electrical contact between support members 34 or A
and contact members 23 and 25 or B and B' effects two pole
switching action.
Alternatively as seen in FIG. 10 the two pole contact members can
be formed by removing a central portion of the loop of member 22,
as by cutting, resulting in contact members 23', 25'. Again with
reference to the schematic electrical circuit of FIG. 9, A
represents the support members 34 while B and B' represent contact
members 23', 25' respectively. In this embodiment it is not
necessary to bend the two contact members from their original
position.
Rather than employ the staple type contact members rivet like
elements may be used as in FIGS. 4-6. Thus rivets 27 and 29 of FIG.
11, similar to headed rivet 70 seen in FIG. 4 are inserted through
apertures in support member 12 and electrically connected, as by
crimping their shanks and soldering to two separate conductive
portions of conductive paths 16 as in the previous multipole
embodiments. As in the previous embodiments the pole contact
members 27 and 29 are represented by B and B' respectively in FIG.
9. It is of course within the purview of the invention to include
three or more conductive rivets to provide three or more pole
switching.
In FIG. 12 the support member corresponding to A of FIG. 9
comprises a sheet or layer 35 of electrically conductive material
connectable to a voltage source in any convenient manner as by
connecting to a portion of conductive paths 16. Sheet 35 is
provided with an aperture 37 for each set of conductive pole
contacts to form a switching cavity. Aperture 37 is generally
circular when used with a conductive element 24 or 76 which also
has a circular periphery. The diameter of aperture 37 is chosen so
that it is slightly less than that of the conductive element 24 or
76 so that the peripheral margin of the element is supported by and
in electrical connection with sheet 35. A carrier sheet 44' is
disposed on top of the conductive sheet and is provided with an
aperture 46' in alignment with each aperture 37. Aperture 46' is
also circular to conform to the conductive element and sized just
large enough to receive the element therein. Thus sheet 44'
similarly to sheet 44 in FIG. 1 provides lateral restraint for the
conductive elements maintaining them in their desired location. As
in the previous embodiments the entire switching area can be sealed
by affixing a sheet 48 of electrically insulative material
thereover. Although not shown, sheet 35 can be employed with the
conductive pole members shown in FIG. 8b and 11 as well as those
shown in FIG. 10.
As in the FIGS. 1-3 and 4-6 embodiment it is preferred that the
support members project outwardly from the surface of insulating
support member 12 a preselected distance which is greater than the
distance that the pole contact members project from the same
surface.
Thus each conductive element is associated with a set of conductive
pole contacts as well as conductive support means. A keyboard made
in accordance with the invention can comprise only multipole
switching key stations or alternatively it can comprise a mixture
of single and multipole switching key stations. Stated in another
way such a keyboard comprises at least one or more sets of
conductive pole contacts having more than a single pole
contact.
Thus, a unique keyboard system has been described in detail in
which a particularly advantageous bridging electrical contact
system is provided, the system being particularly adapted for
incorporation in various systems such as electronic calculators,
computer systems, etc.
Various changes and modifications in the above-described
embodiments will be readily apparent to those skilled in the art
and any of such changes or modifications are deemed to be within
the spirit and scope of the present invention as set forth in the
appended claims.
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