U.S. patent number 3,643,041 [Application Number 05/102,803] was granted by the patent office on 1972-02-15 for pushbutton diaphragm switch with improved dimple actuator and/or capacitance-type switch contact structure.
This patent grant is currently assigned to Unidynamics/Phoenix, Inc.. Invention is credited to Charles A. Jackson.
United States Patent |
3,643,041 |
Jackson |
February 15, 1972 |
PUSHBUTTON DIAPHRAGM SWITCH WITH IMPROVED DIMPLE ACTUATOR AND/OR
CAPACITANCE-TYPE SWITCH CONTACT STRUCTURE
Abstract
A faceplate is provided with a plurality of openings therein,
each representing a digit to be used in a keyboard; a metal switch
plate is positioned immediately beneath the faceplate and includes
a plurality of dome-shaped resilient deformable dimples forming
keys therein, each registering with and extending into a different
one of said openings. An insulating plate, with holes therein
registering with the dimples, separates the switch plate from a
contact board that includes a plurality of contact buttons, each
registering with one of the holes in the insulating plate. The
dimples may be depressed by the fingertip of an operator to "snap"
into contact with a corresponding contact button and will "snap"
back to their original position when fingertip pressure is
released.
Inventors: |
Jackson; Charles A. (Litchfield
Park, AZ) |
Assignee: |
Unidynamics/Phoenix, Inc.
(N/A)
|
Family
ID: |
22291747 |
Appl.
No.: |
05/102,803 |
Filed: |
December 30, 1970 |
Current U.S.
Class: |
200/5A; 200/600;
200/512; 361/288 |
Current CPC
Class: |
H01H
13/702 (20130101); H01H 13/785 (20130101); H01H
2227/004 (20130101); H01H 2203/032 (20130101); H01H
2215/008 (20130101); H01H 2239/006 (20130101); H01H
2223/036 (20130101); H01H 2227/022 (20130101); H01H
2203/004 (20130101); H01H 2209/07 (20130101); H01H
2201/026 (20130101) |
Current International
Class: |
H01H
13/70 (20060101); H01H 13/702 (20060101); H01h
009/26 (); H01h 035/00 () |
Field of
Search: |
;200/1R,5A,DIG.1,159B |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
IBM Technical Disclosure Bulletin, Geil et al., "Elastic Diaphragm
Switch," Vol. 13, No. 7, Dec. 1970 p. 1943. .
IBM Technical Disclosure Bulletin, Barker et al., "Elastic
Diaphragm Switch, Vol. 12, No. 11, April 1970 p. 1923..
|
Primary Examiner: Scott; J. R.
Claims
I claim:
1. A keyboard for effecting an electrical change upon depression of
keys by the fingertips of an operator, comprising: a switchplate,
having a plurality of resilient deformable dimples forming keys
therein, each having a convex surface; a contact board, positioned
adjacent and parallel to said switchplate, having a plurality of
electrical contacts, each registering with a different one of said
dimples; insulating means electrically insulating said contact
board from said switchplate; each of said dimples, when depressed
by an operator's fingertip depressing the convex surface thereof,
contacting a corresponding one of said contacts, and when released
snapping back to its original position.
2. A keyboard for effecting an electrical change upon depression of
keys by the fingertips of an operator, comprising: a faceplate
including a plurality of openings thereon; a switchplate,
positioned parallel to said faceplate, having a plurality of
resilient deformable dimples forming keys therein, each having a
convex surface registering with and extending into a different one
of said openings; a contact board, positioned adjacent and parallel
to said switchplate, having a plurality of electrical contacts,
each registering with a different one of said dimples; insulating
means electrically insulating said contact board from said
switchplate; each of said dimples, when depressed by an operator's
fingertip depressing the convex surface thereof, contacting a
corresponding one of said contacts, and when released snapping back
to its original position.
3. A keyboard for effecting an electrical change upon depression of
keys by the fingertip of an operator, comprising: a faceplate,
including a plurality of openings therein; a metal switchplate,
positioned parallel to said faceplate, having a plurality of
dome-shaped resilient deformable dimples forming keys therein, each
having a convex surface registering with and extending into a
different one of said openings; an insulating plate, positioned
adjacent to and parallel to said switchplate, having a plurality of
holes, each registering with a different one of said dimples; a
contact board, positioned adjacent to and parallel to said
insulating plate, having a plurality of electrical contacts, each
registering with a different one of said holes; each of said
dimples, when depressed by an operator's fingertip depressing the
convex surface thereof, extending through one of said holes and
contacting a corresponding one of said contacts, and when released
snapping back to its original position.
4. The combination set forth in claim 2, wherein each of said keys,
when depressed, transmits a mechanical sensory feedback signal in
the form of a snap sensation through the fingertip of the operator
to indicate that the key has been properly depressed.
5. The combination set forth in claim 2, wherein said switchplate
is a continuous flat metal sheet having a plurality of dome-shaped
resilient deformable dimples therein.
6. The combination set forth in claim 2, wherein said switchplate
comprises a continuous sheet of plastic material having a
metallized surface thereon, said metallized surface including the
concave surfaces of said dimples.
7. A keyboard for effecting an electrical change upon depression of
keys by the fingertips of an operator, comprising: a faceplate,
including a plurality of openings therein; a switchplate positioned
parallel to said faceplate, having a plurality of dome-shaped
resilient deformable dimples forming keys therein, each having a
convex surface registering with and extending into a different one
of said openings; an insulating plate positioned adjacent and
parallel to said switchplate; a contact board positioned adjacent
and parallel to said insulating plate, having a plurality of
electrical contacts, each registering with a different one of said
dimples, a predetermined capacitance existing between each of said
dimples and the corresponding electrical contact; each of said
dimples, when depressed by an operator's fingertip depressing the
convex surface thereof, contacting said insulating plate and
changing the capacitance between the dimple and corresponding
electrical contact.
8. The combination set forth in claim 7, wherein each of said keys,
when depressed, transmit a mechanical sensory feedback signal in
the form of a snap sensation through the fingertip of the operator
to indicate that the key has been properly depressed.
9. The combination set forth in claim 7, wherein said switchplate
comprises a continuous flat metal sheet having a plurality of
dome-shaped resilient deformable dimples therein.
10. The combination set forth in claim 7, wherein said switchplate
comprises a continuous sheet of plastic material having a
metallized surface thereon, said metallized surface including the
concave surfaces of said dimples.
Description
The present invention pertains to keyboards, and more particularly,
to keyboard switching devices suitable for use in those instances
where keyboard size is a design factor.
Miniaturization of electronic components and the introduction of
integrated circuitry has enabled the reduction in size and bulk of
many electrical devices; however, in numerous applications of
electronic technology, there exists the requirement for a
mechanical interface between the human operator and the electronic
apparatus.
One such application of miniaturization is in the field of
calculators wherein the heretofore bulky mechanical and
electromechanical operations may now be performed by compact
electronic techniques, such as integrated circuitry, etc. The
requirement nevertheless exists for a mechanical interface in the
form of a keyboard to permit the operator to enter the required
information for subsequent calculation. The keyboard therefore
becomes a critical element in determining the size of such a
device. An attempt to miniaturize a keyboard has previously
resulted in the incorporation of undesirable features. For example,
it is desirable to incorporate a mechanical sensory feedback signal
to the operator to enable the operator to determine by touch
whether or not the key of the keyboard has properly been depressed.
With larger keyboards and with concomitant larger displacements of
mechanical keys, this touch signal is inherent in the "feel" of the
keyboard; however, in reducing the size of the keyboard and the
length of travel of any key in the keyboard, the sense of touch
becomes critical.
It is therefore an object of the present invention to provide a
keyboard that is compact.
It is also an object of the present invention to provide a keyboard
incorporating a positive mechanical displacement with a minimum of
bulk.
It is still another object of the present invention to provide a
keyboard that can be constructed in very little space and
nevertheless provide a mechanical sensory feedback signal through
the fingertip of the operator.
These and other objects of the present invention will become
apparent to those skilled in the art as the description thereof
proceeds.
The present invention may be described by reference to the
accompanying drawings, in which:
FIG. 1 is a perspective view of a calculator incorporating the
keyboard of the present invention.
FIG. 2 is an exploded view of a keyboard incorporating the
teachings of the present invention.
FIG. 3 is a cross-sectional view of a portion of the keyboard of
FIG. 1, showing a single key thereof.
FIG. 4 is a cross-sectional view of the key of FIG. 3, shown in a
closed-circuit position.
FIG. 5 is a cross-sectional view illustrating a key of another
embodiment of the present invention.
Referring now to FIG. 1, a calculator 10 is schematically
illustrated in the form of a small block having a window 11 for
viewing an alphanumeric display (not shown). The calculator
includes a keyboard generally indicated at 12, having a plurality
of keys 14 arranged in a convenient manner to be depressed by the
fingertip of an operator, thus entering the required information
into the calculator.
Referring now to FIG. 2, the keyboard 12 of FIG. 1 is shown in
greater detail and in an exploded form. The keyboard includes a
metal faceplate 16 having a plurality of openings 18 therein. A
metal switch plate 20 is mounted immediately below and in contact
with the cover plate 16. The switchplate 20 is formed of a
continuous flat metal sheet having a plurality of dome-shaped
resilient deformable dimples 22 therein. The dimples 22 are convex
upward and register with and extend into corresponding openings 18.
Immediately below the switchplate 20 an insulating spacer 24 is
provided and may be formed of any convenient insulating material
such as Mylar having a plurality of holes 26 therein. As may be
seen in FIG. 2, the holes each register with a different one of the
dimples 22 of the switchplate 20. Positioned below the insulating
plate 24 and in contact therewith is a contact board 28 that may
also be formed of any convenient insulating material, such as found
in printed wiring boards. Contact buttons or rivets 30 are secured
to the contact board 28 and are positioned in registration with the
holes 26, dimples 22, and openings 18. The faceplate 16,
switchplate 20, insulating plate 24, and contact board 28 form a
"sandwich" which is extremely compact and occupies only a top thin
layer of the calculator 10.
A cross-sectional view of one of the keys of FIGS. 1 and 2 is shown
in FIG. 3. It may be seen by reference to FIG. 3 that the dimple 22
is convex upward and extends into the opening 18. An electrical
circuit (not shown) may be connected between the switchplate 20 and
any one of the contact buttons 30. The circuit selected to be
energized would, of course, depend on which of the buttons 30 comes
in contact with its corresponding dimple 22.
The operation of the keyboard of the present invention may be
described by reference to FIGS. 3 and 4, wherein it may be seen in
FIG. 3 that no electrical contact exists between the dimple 22 and
the button 30. The operator's fingertip is placed in the opening 18
of the faceplate 16 and contacts the convex surface of the dimple
22. Downward pressure on the dimple will be resisted until a
certain predetermined force is exerted, whereupon the dimple
"collapses" with a snap action, resulting in the convex portion of
the dimple becoming concave and the dimple contacting the button
30, as shown in FIG. 4. This snap action results in a mechanical
sensory feedback signal through the fingertip of the operator. The
sensation received by the operator is a snap sensation similar to
that received when operating a toy clicker device which emits an
audible clicking sound when depressed. The action of the dimple
while collapsing is a modified overcenter action wherein a force on
the convex portion of the dimple beyond a predetermined portion
results in the collapse of the dimple but does not cause the dimple
to permanently assume a convex shape; rather, immediately upon
releasing the dimple, it will snap into its original shape. This
snap action provides the operator with a desirable mechanical
sensory feedback signal which enables him to determine that the key
has properly been depressed.
The switch plate may be formed of a continuous flat metal sheet as
mentioned previously; however, it has been found that good results
are achieved utilizing a continuous flat plastic sheet having the
bottom surface thereof metallized such as by coating with a film of
aluminum.
The snap action may be achieved through a variety of switch plate
and dimple dimensions. For example, it has been found that suitable
action has been achieved through the utilization of a switch plate
formed of a continuous flat metal sheet of stainless steel having a
thickness of approximately 0.001 inch and with dimples formed
therein having approximately 1/2-inch diameter and a maximum height
of approximately 0.03 inch. It has been found that these dimensions
provide suitable key sizes for the average operator's fingertips,
while providing excellent mechanical sensory feedback signals.
Obviously, dimensional variations may be incorporated in the
keyboard without departing from the spirit thereof.
The keyboard described above incorporates switches which make or
break electrical contact between dimples 22 and corresponding
contact buttons 30; another embodiment of the present invention is
shown in FIG. 5. In FIG. 5, the faceplate 16, opening 18,
switchplate 20, dimple 22, and contact board 28 are identical to
those described above. In the embodiment shown in FIG. 5, however,
the insulating plate 35 is a continuous flat insulating sheet
without openings or holes and thus insulates the dimple 22 from the
button 36. Also, the button 36 incorporates a somewhat larger upper
surface 37 for reasons to be explained. When the dimple 22 is
depressed as shown in FIG. 5, the capacitance existing between the
button 37 and the dimple 22 is substantially greater than when the
dimple is in its original position. Therefore, a circuit connected
between the button 36 and the switchplate 20 will incorporate a
variable capacitance depending on the position of the dimple 22
with respect to the button 36. Conventional capacitance change
sensed circuitry may be utilized to detect this change in
capacitance resulting from the depression of the dimple 22, thus
providing a keyboard operable through an induced change in
capacitance at the selected keys.
It may therefore be seen that the keyboard of the present invention
utilizes a minimum volume while nevertheless permitting a larger
number of keys to be incorporated. In addition, the keyboard
provides a mechanical sensory feedback signal through the fingertip
of the operator while nevertheless requiring minimal key travel.
The "sandwich" arrangement of the plates and spacers automatically
isolates the contact buttons 30 from the atmosphere or from
contamination through the openings 18 in the faceplate. The snap
action of the respective dimples when contacting their
corresponding contact buttons results in contact cleaning, thus
assuring excellent electrical properties during the life of the
keyboard. It will therefore be obvious to those skilled in the art
that many modifications may be made in the embodiments chosen for
illustration without departing from the spirit of the
invention.
* * * * *