U.S. patent number 3,676,616 [Application Number 05/099,864] was granted by the patent office on 1972-07-11 for eds serial switch array.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Fritz S. Wiedmer.
United States Patent |
3,676,616 |
Wiedmer |
July 11, 1972 |
EDS SERIAL SWITCH ARRAY
Abstract
In a keyboard, an elastic diaphragm switch array providing
mechanical strobe and rollover protection, and/or a serial signal
output. The switch includes a diaphragm, a separator, and a switch
card. The diaphragm comprises a gold-plated continuous sheet of
thin spring material and serves as a ground or voltage plane or
voltage adder. The switch card has a conductive switch array (or
pie section pattern) at each key location and may have twice as
many pie sections as there are bits in the code to be produced or
voltage transitions desired in the output, with additional service
pie sections as desired. Each pie section is wired directly by
double-sided wiring and through-holes in the switch card to the
appropriate output code pin, a positive or negative voltage source,
or other connection. A key button and distributor is provided for
pressing the diaphragm smoothly through the separator to make
contact with the corresponding switch card pie section. In each pie
pattern, at least one of the pie sections is offset from the center
of contact of the key button such that, as the key button is
actuated and the diaphragm pressed through the separator, that pie
section makes contact at a different point in time to provide a
serial code signal output, or provide such service functions as
strobe, rollover protection, switch battery power, or the like.
Inventors: |
Wiedmer; Fritz S. (Saratoga,
CA) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
|
Family
ID: |
22276986 |
Appl.
No.: |
05/099,864 |
Filed: |
December 21, 1970 |
Current U.S.
Class: |
200/5R; 200/16A;
200/512 |
Current CPC
Class: |
G06F
3/0202 (20130101); H01H 13/702 (20130101); H01H
2217/012 (20130101); H01H 2239/026 (20130101); H01H
2225/018 (20130101) |
Current International
Class: |
H01H
13/70 (20060101); H01H 13/702 (20060101); G06F
3/02 (20060101); H01h 003/12 () |
Field of
Search: |
;200/6A,5R,5C,159B,83N,86,11E,11G,11D,11DA,166PC,11TW,16A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schaefer; Robert K.
Assistant Examiner: Smith; William J.
Claims
What is claimed is:
1. A keyboard switch means for making a plurality of contact
closures, comprising
a conductive diaphragm,
a plurality of pie sections, with at least two of said sections
terminating on different radii,
key and distributor means for moving said conductive diaphragm into
contact with said pie sections,
whereby as said key is depressed, at least two of said sections
contact said diaphragm at different times.
2. A serial keyboard apparatus comprising elastic diaphragm switch
means for making a plurality of contact closures comprising
a conductive diaphragm,
a plurality of pie sections, each said section terminating at
different radii, with each pair of pie sections terminating on
adjacent radii defining a bit in the code,
actuating means for bringing said diaphragm into contact with said
pie sections in a serial fashion,
a positive voltage source
a negative voltage source,
each said pair having one pie section connected to said positive
source and the other pie section to said negative source,
voltage summation means connected to said diaphragm for summing the
voltages of all said pie sections in contact with said
diaphragm,
whereby as the key is depressed, the diaphragm contacts the pie
sections in a serial manner and a summation of the voltages of said
sections represents the serial code output of said switch.
3. An elastic diaphragm switch array, comprising
a conductive diaphragm,
a plurality of pie sections,
actuating means for moving said diaphragm into contact with said
pie sections,
each said pie section terminating at a different radius from the
axis of said actuating means.
4. In an elastic diaphragm switch, a plurality of contact closures
comprising
a conductive diaphragm,
a plurality of pie sections,
actuating means for bringing said diaphragm and pie sections into
electrical contact,
at least one of said pie section terminating at a radius different
from the radii of termination of the other sections from the axis
of said actuating means.
5. An elastic diaphragm switch keyboard for generating at least two
output codes, comprising a plurality of switch arrays, each said
array comprising at least two groups of pie elements with one group
terminating at different radii than the other group, and with said
one group connected to output pins associated with one code and
said other group connected to output code pins associated with the
second code, a conductive diaphragm, and actuating means for
bringing said diaphragm and said pie elements into electrical
contact.
6. The switch array of claim 5 characterized by means for detecting
the closure of those switch arrays included in the group
terminating at the largest radii for strobing the output code
generated by the group terminating at the smaller radii.
7. In an elastic diaphragm switch keyboard, a switch array
comprising a plurality of pie sections, with one pie section
extending into the center, and a second pie section terminating at
a radius which is greater than the radii at which the remaining pie
sections terminate, conductive diaphragm means, and actuating means
for bringing said pie sections and said diaphragm into electrical
contact whereby mechanical strobe and rollover protection is
provided.
8. In an elastic diaphragm switch keyboard having a plurality of
switch arrays, each array having a plurality of pie sections,
rollover protection means comprising for each said array a control
pie section extending to the center axis of the corresponding
switch actuator, and means for detecting simultaneous actuation of
two said control sections in different switch arrays.
9. In an electrical diaphragm switch array, mechanical strobe means
comprising
a conductive diaphragm,
a plurality of pie sections,
actuating means for bringing said diaphragm and pie sections into
electrical contact,
one of said pie sections terminating at a radius larger than the
radii about the axis of said actuating means at which the other pie
sections terminate.
10. In a battery-operated elastic diaphragm switch keyboard, a
switch comprising
a conductive diaphragm,
a plurality of pie sections,
actuating means for bringing said diaphragm and said sections into
electrical contact,
one of said sections terminating at a different radius from the
others and said one section being connected to a battery for
drawing current to operate the keyboard only when the switch array
is actuated.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to electrical switching elements for
generating an output code, and more particularly to an array of
pressure-sensitive elastic diaphragm switching elements which are
actuated in a serial fashion and are double-sided wired on a switch
card to output pins.
2. Description of the Prior Art
This invention is related to the EDS (Elastic Diaphragm Switch)
Switch Array and Logic, described in an application of common
assignee, Ser. No. 54,300 filed July 13, 1970. The description of
the prior art contained therein is incorporated herein by
reference.
In the prior art devices, as well as in the co-pending application,
Ser. No. 54,300, buffering logic must be provided to produce a
serial output code for data transmission. Also, strobe and rollover
protection is provided by the addition of logic circuitry for
determining that all contacts have been made, and that there has
been no simultaneous depression of keys. This logic circuitry
raises the complexity of terminal keyboard, thereby increasing the
cost.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an improved
pressure responsive electrical switching element for generating
output signals at different times from a single key action.
It is a further object of the invention to provide an improved
pressure-responsive diaphragm switch having a plurality of
switching elements or pie sections which are double-sided wired on
a switch card substrate to output pins for producing a serial
output code directly without decoding or encoding logic.
It is a further object of the invention to provide an improved
pressure-responsive diaphragm switch having a plurality of
switching elements or pie sections, at least one of which is
actuated before or after the others for providing a serial output
with a single key actuation.
It is a further object of the invention to provide an improved
elastic diaphragm switch having mechanical (as distinguished from
electrical logic circuitry) strobe and rollover protection.
The above objects are achieved by the invention which provides an
electronic switch means comprising at least one key button, a
distributor means, an elastic diaphragm means, separator means, and
a switch card means. The switch card comprises a substrate and at
least one array of switching elements or pie sections. A plurality
of the switching elements or pie sections are electrically
connected by double-sided wiring on the substrate to the output
pin(s) and, in one preferred embodiment, to at least two voltage
sources. The elastic diaphragm comprises a thin continuous sheet of
conductive and spring material which may be deflected by the key
buttons and distributor through the separator into electrical
contact with the array of switching elements or pie sections. At
least one of the pie sections is offset from the center of contact
of the key button by an amount different from that of the offset of
the other pie sections (that is, they terminate at different
radii). As the key button is actuated, the distributor is
compressed and the elastic diaphragm makes contact with the switch
card first at the center or on the axis of the key button and then
within larger diameters until the key button is actuated to its
fully depressed position. Those pie sections which terminate at the
smallest radius from the center axis of the key button are first
brought into contact with the elastic diaphragm, whereas those pie
sections which terminate at the larger radii make contact with the
elastic diaphragm at a later point in time.
The foregoing and other objects, features, and advantages of the
invention will be apparent from the following more particular
description of preferred embodiments of the invention as
illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the switch card array for an eight-key keyboard for
generating a serial output code.
FIG. 2 is a cross-section view (not to scale) of the distributor,
elastic diaphragm, separator, and switch card layers of the serial
keyboard of FIG. 1.
FIG. 3 is voltage diagram showing the voltage at the output of FIG.
1 with respect to time as key 100 is actuated.
FIG. 4 is a diagrammatic view of the pie pattern for a key having
mechanical strobe and rollover protection.
FIG. 5 is a diagrammatic view of a representative switch array and
the associated double-sided wiring for combining two codes and for
providing mechanical and electronic strobe.
DESCRIPTION
Reference is first made to FIG. 1 of the co-pending application
Ser. No. 54,300, showing the elastic diaphragm switch key including
button 40, distributor 50, diaphragm 51, separator 52, and switch
card or base 60. Reference is made to page 5, line 19, to page 9,
line 6, wherein that structure is explained.
Referring again to FIG. 1 of the co-pending application, the
expanding diameter of contact between layers 51 and 60 will be
described. Therein, as key button 40 is depressed, actuator 46 is
driven downwards compressing and deflecting distributor 50 such
that conductive layer 51 is brought into contact with surface Y of
switch card 60 through the hole U in separator 52. The first point
of contact between layers 51 and 60 occurs immediately beneath and
at the axis of actuator 46. As key button 40 continues downward,
the distributor 50 drives or forces more of layer 51 into contact
with layer 60 in successively larger diameters of contact. The
distributor 50 action transforms the actuator motion into the
expanding contact area after the first contact due to the fact that
as soon as the distributor downward motion is stopped, a horizontal
expansion motion occurs in the elastic material of the
distributor.
Inasmuch as distributor 50 is elastic, the material maintains its
volume. Thus, as key button 40 is actuated, the distributor first
is forced through the separator 52, making contact with card 60,
then spreads out in the expanding circle, and returns. The
diaphragm and the distributor can be made of one piece, depending
upon the elasticity of the material selected.
As will be more fully described, with the various pie sections
terminated at different radii about the axis of actuator 46, said
pie sections are brought into electrical contact with layer 51 at
different points in time according to the diameter of contact
between layers 51 and 60.
Referring now to FIG. 1 of this specification, a description will
be given of the serial keyboard of the invention. Switch arrays or
keys 000, 001, 010, 011, 100, 101, 110, and 111, are deposited ,
gold plated, or other wise provided as conductive patterns on
switch card 12. A more detailed representation is given for only
key 000, showing that the various pie elements A, B, C, D, E, F,
terminate at different radii about the center of said key. It
should be understood that these reference letters apply to the
corresponding pie sections of all the keys. Thus, for each of the
keys, the pie section A terminates at the smallest radius and the
pie section F terminates at the largest radius with pie sections
B-E terminating at increasing radii in a clockwise fashion. Through
holes or conductive via-holes J-P are similarly associated with the
corresponding pie sections F-A for interconnecting said pie
patterns and the land patterns on the top of switch card 12 with
the land patterns on the bottom of said switch card. In FIGS. 1 and
5, land patterns appearing on the top of card 12 are shown in solid
lines while those appearing on the bottom of card 12 are shown in
dotted lines.
Each pie section A-F of each key 000-111 is connected by
double-sided wiring and via or through-holes to either +12 volts
pin 26 or -12 volts pin 27. The elastic diaphragm layer 16 is held
in constant contact at 28 with switch card 12. The output pin 36 is
connected through resistance 34 to ground voltage 35 and to contact
28.
As will be described in connection with the output of FIG. 3
hereafter, each pair of pie patterns A-B, C-D, and E-F, have one of
the pair connected to the +12 voltage pin 26 and the other to the
-12 voltage pin 27, and each pie section A-F for a given switch
array is connected to its voltage source through a different
resistor 31-33, 41-43.
+12-voltage source at pin 26 is connected through resistance 31
along wire 301 to pie section 000F; thence through via hole 000J
along line 302 and through via hole 001J to pie section 001F;
thence along line 303 and via hold 010J to pie section 010F; thence
along line 304 and via 011J to pie section 011F; thence along line
305 to pie section 111E; thence through via hole 111K and line 306
through via hole 110K to pie section 110E; thence along line 307
and via hole 101K to pie section 101E; thence along line 308 and
through via hole 100K to pie section 100E.
+12-voltage source at 26 is connected along line 30 through
resistance 32 and along line 311 to pie section 001D; thence
through via hole 001L and land pattern or wire 312 and through via
hole 000L to pie section 000D; thence along line 313 to pie section
100D; thence through via hole 100L and line 314 and through via
101L to pie section 101D and along line 315 and via 110M to pie
section 110C and thence along 316 and via 111M to pie section 111C;
and from pie pattern 000D, along line 317 and via 010M to pie
section 010C; thence along line 318 and via 011M to pie section
011C.
+12-volt source at 26 is connected through resistance 33 along line
321 to pie section 010B; thence along via hole 010N and line 328
and via 011P to pie section 011A; from pie section 010B along line
324 to pie section 110B; thence through via hole 110N along line
327 and via hole 111P to pie section 111A; from pie section 110B,
through via hole 110N along line 325 and via hole 101P to pie
section 101A; thence along line 326 and via hole 110N to pie
section 100B; also, from pie section 010B through via 010N along
322 and through via hole 001P to pie section 001A; thence along
line 323 and through via hole 00N to pie section 00B.
-12 volts at 27 is connected through resistance 41 along line 401
to pie section 00E; thence through via hole 000K along line 402 and
through via hole 001K to pie section 001E; thence along line 403
and through via hole 010K to pie section 010E; thence along line
404 and through via hole 011K to pie section 011E; thence along
line 405 to pie section 111F; thence along through via hole 111J
along line 406 and through via hole 110J to pie section 110F;
thence along 407 and through via hole 101J to pie section 101F;
thence along 408 and through via hole 100J to pie section 100F.
-12-volt input at 27 is connected through resistance 42 along line
421 to pie section 001C; thence through via hole 001M along line
424 and through via hole 000M to pie section 000C; thence along
line 425 to pie section 100C; thence through via hole 100M along
line 426 and through via hole 101M to pie section 101C; thence
along line 427 and through via hole 110L to pie section 110D;
thence along line 428 and through via hole 111L to pie section
111D; from pie 001C through via hole 001M along line 422 and
through via hole 010L to pie section 010D; thence along line 423
and through via hole 011L to pie section 011D.
Finally, -12-volt input at 27 is connected through resistance 43
along line 430 to pie section 010A; thence through via hole 010P
along line 437 and through via hole 000P to pie section 000A; from
pie section 010A through via hole 010P along line 431 and through
via hole 011N to pie section 011B; thence along line 433 through
via hole 011N along line 436 and through via hole 101N to pie
section 101B; from pie section 111B through via hole 111N along
line 434 and through via hole 110P to pie section 110A; thence
along line 435 and through via hole 100P to pie section 100A.
The land patterns, lines or wires referred to in FIG. 1 and shown
as dotted lines are provided on surface 17 of switch card 12 as
shown in FIG. 2, and those which appear in FIG. 1 as solid lines
are deposited or otherwise provided on surface 13 of switch card 12
as shown in FIG. 2. The various via holes J-P go through switch
card 12 to interconnect surfaces 13 and 17. Elastic diaphragm layer
16 is provided on the bottom surface of distributor 15, as shown in
FIG. 2.
Referring now to FIG. 3, the voltage output at pin 36, representing
the summation of all voltage drops between pins 26 and 27 to ground
35 through diaphragm plane 16 will be described for key 110. Before
the key button actuator corresponding to key position 110 is
depressed, the output at pin 36 is represented as 0 voltage 9 in
FIG. 3. As the key is depressed, the first pie section to draw
current is 011A, that pie section which extends furthest in toward
the section of the key switch array or which terminates at the
smallest radius. With pie section 110A in contact with diaphragm
16, current flows from negative voltage source 27 through
resistance 43 and 34 to ground pin 35, resulting in the negative
voltage at output pin 36 is shown as the negative signal at 9A in
FIG. 3. As the key button is further depressed, the diameter of the
area of contact between diaphragm 16 and switch card 12 increases
until pie section 110B makes contact with the diaphragm 16. At that
time, the +12 voltage source at pin 26 is connected to ground 35
through resistances 33 and 34. The output voltage which appears at
9B in FIG. 3 is zero, representing the division of the voltage
across resistances 33 and 43. As the diaphragm contact circle
reaches out to include pie section 110C, current is drawn through
resistance 32 from the positive voltage source and added to the
current being drawn through pie sections 110A and 110B to produce
the positive output voltage 9C at pin 36. As pie section 110D makes
contact with the diaphragm 16, current is drawn through resistance
42 from the negative voltage source; when added to the other
currents, this gives a zero current through resistor 34 or zero 9D
output at pin 36. Finally, as the diaphragm 12 makes contact with
the pie sections 110E and 110F, those pie sections which terminate
at the largest radii, current is drawn through all resistances
31-33 and 41-43, and added to produce an output 9F of zero at
output pin 36. When the key button is released, the reverse process
takes place; the circumference of the area of contact of diaphragm
16 with switch card 12 becomes smaller until all contact is lost
and a zero output voltage 8 appears at pin 36.
In summary, herein, each pie section A-F of a given key, such as
key 110, is connected to either a 12K resistor which is connected
to +12 volts or a 12K resistor connected to -12 volts. Each bit
position is made out of two consecutive pie shapes, one of which is
connected to the positive voltage and the other to the negative
voltage. Depending on sequence in which they are connected, a
positive or negative current pulse will flow through the diaphragm
for each output code bit. The diaphragm 16 is connected to ground
35 over the 1K resistor 34 across which the output voltage is
generated. Such a keyboard, therefore, has 2N + 1 resistors where N
is the number of bits on the code. The code is produced in reverse
when the key is lifted and this can be used for error
detection.
While the serial switch array shown in FIG. 1 at switch 000 shows
each switch element A-F terminating at a slightly larger radius
from element to element in a clockwise direction, it is not
necessary that adjacent pie sections terminate on adjacent radii.
For the purposes of the serial configuration described in FIGS. 1
and 3, it is only essential that the two pie sections comprising a
given bit in the output code terminate on adjacent radii. Thus, for
example, while pie section A and B must terminate on adjacent
radii, they need not be placed adjacent to each other in the
pattern shown.
The operator of the keyboard may require some form of feedback to
know that he has depressed a given key all the way to make contact
between the diaphragm and all of the pie sections. Feedback can be
provided by light or by a tone or visually as by TV display change.
The feedback can be generated by an additional pie section with
greater radius than all others or by electronic logic.
Referring now to FIG. 4, the pie section array for a single key on
a keyboard having mechanical strobe and rollover protection will be
explained. Starting with a standard six pie sposition 52-57 switch
array similar to those described in the co-pending application, two
service pie sections 51 and 58 are added. One service pie section
51 comes further to the center 50 than all the o ers and therefore
will make the first or early contact with the diaphragm as it is
depressed into contact with the switch card by the key actuator.
This pie section 51 may be used to provide rollover protection
between keys. That is, each early contact, when made, draws a small
current through a resistor (not shown) and these currents are
summed in a common resistor. The voltage discriminator to detect
whether or not two early pie sections 51 from more than one key are
simultaneously depressed. If no rollover protection is necessary,
it is still desirable to fill the center of the pie switch with
say, gold-plated copper so that there are no holes in the surface
presented to the diaphragm that are larger than the separation
between the pie sections of approximately 5 mil. This is done in
order to exclude the possibility of permanent deformation of the
diaphragm. The data pie sections 52-57 end far enough from the
center so that none is contacted before the early contact is made
to pie section 51 at portion 50. The other service pie section 58
ends still further out from the center so that it is always "made"
(or contacted) last, and therefore it can be used to strobe the
data pie sections. If rollover is not used, this strobing would be
done by supplying data common to the diaphragm through the
strobe-pie section.
Referring further to FIG. 4, a battery-operated terminal variation
of the embodiment described above will be discussed. In a
battery-operated terminal, it is important that the battery be used
only during actual key depression and not in between key operation
or during idle time of the terminal. In such a terminal, the code
would be generated by pie sections 52-57 and either pie section 51
or 58 of all the key positions in the keyboard would be connected
in parallel to operate a reed relay, for instance, that connects
the battery to the terminal electronics. If current consumption is
low enough, the paralleled pie sections 51 or 58 themselves can be
used to connect, say, the diaphragm to the battery ground
terminal.
Referring now to FIG. 5, a further embodiment of the invention will
be described. In FIG. 5, only one key of a plurality of key
positions in a keyboard is shown. Pie positions 62, 64, and 66 are
shown connected to wires 61, 63, and 65 to a circuit block 60 which
includes, for example, the 12 output code of a 3 of 14 code
terminal as described in the co-pending application. Circuit 60 may
further include electronic strobe and rollover protection as
described in said application. Key locations 71-79 are similarly
shown connected to circuit box 70 by double-sided wiring including
lines 81-89 and 91-93, 98, 99. Circuit 70 represents the output
code pins, for example, of an ASCII, BCD, or EBCDIC device. As
shown, pie sections 62, 64, 66, terminate at a larger radius than
pie sections 71-79. In this manner, it is possible to generate two
output codes from a single key switch array, and to combine
mechanical and electronic strobe. Thus, the 3 of 14 code generated
in circuit 60, for example, may include electronic strobe and
rollover. Then, the code generated in circuit 70 may be strobed by
the contact of the three short pie sections 62, 64, 66, represented
by the electronic strobe on these contacts.
As will be apparent, many possible combinations of short and long
pie sections, connected by double-sided wiring to different
utilization devices, may provide different output codes and utilize
various strobe and rollover protection techniques.
While the invention has been particularly shown and described with
reference to preferred embodiments thereof, it will be understood
by those skilled in the art that the foregoing and other changes in
form and details may be made therein without departing from the
spirit and scope of the invention.
* * * * *