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Patent 2186789 Summary

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(12) Patent: (11) CA 2186789
Status: Deemed expired
Bibliographic Data

English Abstract

A computer keyboard having membrane switches activated by finger touch keys
supported by an upper resilient layer of the membrane circuit board. The keys
a rigid projection fixedly secured to the finger touch part of the key. The
key is
depressable against the resiliency of the upper layer to make circuit contact.
key is guided during movement and has a short travel distance as well as very
touch for circuit activation. The keyboard addresses the problem of keyboard
related repetitive strain injuries (RSI's) and other disabilities requiring a
"feather light
touch" in a computer keyboard.


Note: Claims are shown in the official language in which they were submitted.

I claim:
1. A computer keyboard comprising:
(a) a membrane circuit board having a resilient upper switch circuit layer, a
lower switch circuit layer and an insulative layer disposed therebetween,
through said insulative layer aligned with predetermined circuit paths on said
upper and lower switch circuit layers for completing predetermined circuits by
physical contact of conductive material on one of said layers with conductive
material on the other of said upper and lower layers;
(b) a push button key for each of respective ones of said holes, each said
button key having a downwardly extending rigid projection fixed thereto and
aligned with the hole associated therewith, each said key, in a key at rest
open position being supported by said upper resilient layer, said keys being
movable from their at rest position in a direction toward said lower layer
to cause physical contact of the conductive material on said respective upper
lower layers; and
(c) means, on said key board, resisting movement of said keys, from their at
position, in a direction away from said upper layer.
2. A computer keyboard as defined in claim 1 including means guiding said keys
during movement of the same.
3. A computer keyboard as defined in claim 2 wherein said movement resisting
guide means includes a socket for each of respective ones of said keys.
4. A computer keyboard as defined in claims 1, 2 or 3 wherein each said push
key has a plate portion with said rigid projection extending downwardly from a
central portion of an underside portion of said plate portion, a further
extending downwardly from said plate portion at a position spaced outwardly

said rigid projection, said further projection having an outwardly directed
hook for
engagement with an abutment means and thereby provide said means resisting
movement of said keys in a direction away said upper layer.
5. A keyboard as defined in claim 2 wherein said guide and movement resisting
include a socket member having an annular space surrounding a post means, a
flange projecting inwardly into said annular space, said further projection
located in said annular space such that the outwardly directed hook thereon is
engagable with said flange and thereby prevent the key from being dislodged
from said socket.
6. A computer keyboard comprising:
(a) a lower circuit sheet means comprising a first sheet of insulating
material with
a first electrically conductive means thereon;
(b) an upper circuit sheet means overlying said lower sheet means and
comprising a second resilient sheet of insulating material with a second
electrically conductive means on a surface thereof facing said first
conductive means;
(c) spacer means disposed between said first and second circuit sheet means;
said spacer means having a plurality of openings therein permitting physically
moving preselected portions of said second electrically conductive means into
contact with said fast electrically conductive means for selectively
completing predetermined circuits;

(d) a push button key for each of respective ones of said plurality of
openings, each
said push button key having a downwardly extending rigid projection fixed
and aligned with the opening associated therewith, each said key having the
rigid projection thereof in physical contact with said upper resilient sheet,
said key being supported by said resilient sheet in an at rest open circuit
and being movable from said rest position in a direction toward said lower
thereby to cause said physical contact of the conductive material on said
respective upper and lower sheets; and
(e) means, on said key board, resisting movement of said keys, from their at
position, in a direction away from said upper sheet.
7. A computer keyboard as defined in claim 1 including a layer of compressible
elastomeric material on said upper circuit layer, said elastomeric material
having a predetermined compressibility value.
8. A computer keyboard as defined in claim 7 including a thin protective layer
disposed between said rigid downward projection on said push button key and
the elastomeric material.
9. A computer keyboard as defined in claim 8 wherein the compressibility of
elastomeric material is such that a force of approximately 50 grams on the
push button key is required to active a circuit.


Note: Descriptions are shown in the official language in which they were submitted.

CA 02186789 1998-08-05
This invention relates to computer fingerboards and more particularly to an
improved key construction that reduces the travel distance, provides lighter
and reduces manufacturing costs. Keys of the present invention are primarily
intended far ergonomic keyboards, palmtops and Laptops. The light touch and
travel distance address the problem of keyboard related repetitive strain
(RSI's). The travel distance allows for a thinner design of notebooks,
palmtops and
portable ergonomic keyboards. The invention also has applications regarding
adaptive and alternative {AAC) computer input devices for people with
Keyboard related repetitive strain injuries (RSI's) are among the top causes
Workman's Compensation claims in North America. Consequently, ergonomics is
one of the fastest growing aspects of the computer industry. Some feel that,
the advent of voice recognition, the problem of RSI's will soon become a thing
of the
past. However, many speech pathologists disagree with this vision. There are
already reports documenting voice injuries related to voice recognitian data
input. In
fact, the voice may be a more volatile stress area than the carpal tunnel or
Therefore the computer industry must continue to provide ergonomic keyboard

CA 02186789 1998-08-05
alternatives to RSI sufferers for perhaps some time to come. Many ergonomic
keyboards presently in use deal with the important issue of hand positioning
but they
fail to address the critical issue of key resistance to travel and/or key
distance of
travel. For this reason thousands of RSI sufferers cannot use these devices.
present is directed to this serious failing of curren~k ergonomic keyboards.
In the known membrane technology there are membrane key switches,
membrane touch activated switches and key switches. In the conventional
membrane key switch there is a resilient biasing member as well as the "spring
effect" of the membrane mechanism. This combined resistance requires more
than many RSI suffers can endure. For an example of a membrane key switch,
reference may be had to USP 4,515,998 issued to Harper and entitled "Full
Keyboard."' Touch activated membrane switches require less force than membrane
key switches but the force of the strike is distributed over the entire
surface of the
finger (contact point) which is about 1.5 cm. This wide distribution of force
translates into more resistance than many RSI sufferers can tolerate during
hours of data input. For an example of a known touch membrane switch,
may be had to USP 5,0~2,07T issued Cfec. 10, 1 891 to Harold Klein entitled
"Monolithic Membrane Switch".
A push button of a notebook computer key, as seen in USP 5,145,058 issued
Sept. 8, '92 to Sam San Lee entitled "Notebook computer Key", has a plate
a hook projection extending downward from the plate portion and having a
outward hook end, and a conductive member spaced vertically downward from the

CA 02186789 1998-08-05
plate portion The hook projection extends into an upright hollow confining
wall of a
socket member. The top end of the socket member is provided with an inwardly
extending peripheral flange to hinder movement of the distal hook end out of
receiving space to prevent detachment of the push button from the socket
A circuit board is provided on a lower end of the socket member. An upright
guide projection extends from the circuit board and into the hollow confining
wall of
the socket member. The conductive member is disposed inside the guide
projection. A resilient biasing member has a lower tubular section, an upper
section wider than the tower tubular section wider than the lower tubular
section and
supporting the plate portion of the push button, and a gradually expanding
section connecting the lower and upper tubular sections. The biasing member
biases the conductive member away from the circuit board.
An object of the present invention is to provide a key and a keyboard
incorporating the same in which each key has minimum resistance to movement
and a short travel distance, thereby requiring a shorter distance for the
finger to
travel, and also a keyboard which is simpler and less expensive to produce.
Another object is to provide a key with reduced height thus allowing for easy
transport, a thinner palmtop, laptop (or ergonomic computer keyboard) design
maintaining the present "look and feel°° of conventional keys.

CA 02186789 1998-08-05
A key of the present invention has "feather fight touch" and, as such, will
not be
desirable to all keyboardists. However, for many RSI suffers (or potential RSI
sufferers) and disabled persons who must have law resistance and minimal
movement, a key of the present invention provides an ideal solution.
A key of the present invention is essentially the same as a conventional
membrane key switch but differs therefrom by eliminaking the resilient biasing
member that returns the finger touch part of the key to it's raised position.
essence, the key of the present invention comprises a rigid finger touch
part having a downwardly projecting part that rests on and remains in contact
the protective layer of a membrane switch and a guide for said rigid part. The
projection on the rigid key part thus rests on the protective layer while the
key is not
actuated and when the key is pressed, circuit contact occurs. The insulating
material and or protective layer of the membrane switch is the only source of
resilience during key activation. This substantially reduces the resistance to
movement, reduces the key height and the distance that the key travels
during key activation. Therefore membrane key switch of the present invention
for example have a resistance of less than 50 gms., which is 1/5th that of
conventional key switches. The "look and feel" of a conventional key switch is
The reason that the key of the present invention has a lighter touch than that
membrane touch switches is that the force during key strike is distributed
over the
area of the end of the downward projection that engages the upper deformable

CA 02186789 1998-08-05
of the membrane. This area of contact atong with the characteristics of the
and resilient layer can be predetermined to give tt~e desired resistance. The
the key of the present invention it has a lighter touch than conventional key
is that it's only source of resilience is from the membrane switching array.
contains no resilient biasing member. This is of extreme significance to the
sufferer and those requiring a °°feather light touch."
The invention is illustrated by way of example with reference to the
drawings, wherein:
FIG. 1 is a sectional view of a prior art finger touch membrane switch
FIG. 2 is a sectional view of a membrane key switch of the present invention;
FIG. 3 is an exploded part sectional view of a membrane key switch of the
FIG. 4 is a sectional view of the key membrane switch of the present invention
in a
switch activated position (key depressed);
FIG. 5 is a sectional view on a larger scale of the membrane section of the
and a portion of the key projection contact therewith;
FIG. 6 is a bottom view of the key button;
FIG. 7 is a side view of the key button;
FIG. 8 is a top view of the socket; and

CA 02186789 1998-08-05
FIG. 9 is an oblique view of the socket
Illustrated in FiG. 1 a typical membrane switch and particularly the ane
disclosed in the aforementioned USF~ b,0'~2,07~. The keyboard assembly is
completed by an array of mechanical key elements associated with and for the
purpose of actuating each of the individual key locations in the membrane
The key elements deliver actuating farce to the key locations or key sites of
membrane keyboard, and the key elements include apparatus for precise
displacement of a key cap prior to the making of electrical contact with the
membrane array to provide the operator of the switch and keyboard with the
sensation of pretravel. The key elements also include a geometrically defined
configuration for compressing the elastomeric material on the upper portion of
membrane array both before and after closing the membrane switch, so that
compression of the elastomeric material both contributes to the sense of
and generates the overtravel perceived by the keyboard operator.
Keyboards made in accordance with the present invention have switching life
and reliability equivalent to thane found in capacit~ue type arrays, while at
the same
time having significantly reduced cost for the assembled keyboard and
fewer plastic parts and springs than in prior art assemblies of this type.
Also, these

CA 02186789 1998-08-05
advantages of the present invention are accomplished in a configuration in
the human factor variable requirements are met.
The elastomeric layer on the membrane switch array acts as a spring element
both to contribute to pretravel and to distribute the closure force from the
key stem
uniformly over the entire area of the membrane switch (i.e., the area defined
at each
opening in the spacer or separator layer). The eiastomeric layer also
contributes the
sensation of overtravel and it can also provide for quiet, "clack" free
operation when
the actuator/elastomeric interface is properly defined. The membrane key
itself contributes a spring characteristic in that wt moves from the separated
open circuit configuration to a mechanically and electrically closed state in
to the application and imposition of a specifically defined actuating force,
accomplishing control of the actuating or "'fire" point.
A protective layer 50 is bonded to the upper face of layer 12. Referring to
there is illustrated an embodiment of the computer key is shown to comprise of
push button 30, a socket member, 4~, and a circuit board 70. The membrane
board may be as illustrated in FIG.1 and/or other known construction.
The push button 30 has a slightly concave plate potion with a dawnwardly
extending and outwardly inclining peripheral flange 31 on three sides and a
downwardly extending peripheral flange 32 an the fourth side (see FIG. 6). A
tubular projection 33 extends downward from the underside of the plate portion
the plate portion 30. A pair of spaced hook projections 34 extend downward by

CA 02186789 1998-08-05
tubular projection 33. Each hook projection 34 is provided with a distal
hook end 35.
The socket member 40 is in a plate 60 that overlies the membrane circuit
The socket 40 is defined by a wall 61 projecting upwardly from the plate 60
an opening 62. The wall 61 has an extending peripheral flange 63 that is
engageable with hook ends 35 of the projections 34 on the key or push button.
prevents detachment of the push button from the socket member 40.
When the switch is at an at rest position (not actuated), the tubular
projection 33
rests on theprotectivelayer 50 of the monolithic circuit board 18.
A membrane circuit board 70 is shown in an enlarged scale in FIGS. 1 & 5 and
includes a bottom stiffener layer 8, a passive membrane switch circuit layer
thereon, an insulating spacer or separator 14 on the passive membrane layer 10
and an active membrane layer switch circuit 12 on the other side of the spacer
Both the passive and active membrane layers 10, 12 have electrical conductors
thereon (formed by printed circuit techniques] arranged in a geometrical
pattern and
cooperating with the holes 38 in the separator layer 14 to define an array of
switch and circuit locations. The application of an appropriate force to push
30 causes via projection 33 the active layer and its particular switch
component to
make physical and electrical contact through the appropriate hole 38 in the
14 with the circuit pattern on the fixed or passive layer 10 of the membrane.

CA 02186789 1998-08-05
A layer of elastomeric material 50 is positioned on and attached to the upper
surface of the active layer 12 of the membrane switch array. The elastomeric
material can be chosen to provide a suitable compressibility factor or example
it can,
if desired, provide switch contact with a finger force of less than 50 gms. on
the key
30. The elastomeric material 50 andlor layer 12 having the printed circuit on
underside thereof must have sufficient stiffness to support the weight of the
unactuated push button 30 so that the switching array would not be activated
the push button is at rest. The contact area of projection 33, the size of
hole 38, the
thickness of layer 14, the resiliency of layers 50, 12 and/or 14 can be varied
and co-
related to provide a selected desired soft touch and travel distance for the
The hook engagement between the hook projections 35 and the socket member
40 facilitates the assembly and disassembly of the push button 30 from the
member 40.
There has been described herein an ergonomic membrane key switch that does
not have separate resilient biasing member as for example the aforementioned
5,145,058 and therefore requires significantly less activating force than a
conventional membrane key switch of the type for example illustrated in
aforementioned USP 5,072,077 because in the latter activating force is
over a wider contact surface. In the present invention the moveable key is
rigid and
in physical contact with the membrane circuit board. The key is guided in its
movement and snap fits into the socket.

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2006-01-31
(22) Filed 1996-09-30
(41) Open to Public Inspection 1998-03-31
Examination Requested 2003-07-18
(45) Issued 2006-01-31
Deemed Expired 2010-09-30

Abandonment History

Abandonment Date Reason Reinstatement Date

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1996-09-30
Maintenance Fee - Application - New Act 2 1998-09-30 $50.00 1998-09-24
Maintenance Fee - Application - New Act 3 1999-09-30 $50.00 1999-09-24
Maintenance Fee - Application - New Act 4 2000-10-02 $50.00 2000-09-26
Maintenance Fee - Application - New Act 5 2001-10-01 $75.00 2001-09-10
Maintenance Fee - Application - New Act 6 2002-09-30 $75.00 2002-09-27
Maintenance Fee - Application - New Act 7 2003-09-30 $75.00 2003-07-16
Request for Examination $200.00 2003-07-18
Reinstatement: Failure to Pay Application Maintenance Fees $200.00 2004-10-14
Maintenance Fee - Application - New Act 8 2004-09-30 $100.00 2004-10-14
Maintenance Fee - Application - New Act 9 2005-09-30 $100.00 2005-08-01
Final Fee $150.00 2005-11-22
Maintenance Fee - Patent - New Act 10 2006-10-02 $125.00 2006-09-18
Maintenance Fee - Patent - New Act 11 2007-10-01 $125.00 2007-09-14
Maintenance Fee - Patent - New Act 12 2008-09-30 $125.00 2008-09-04
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
Past Owners on Record
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Number of pages   Size of Image (KB) 
Representative Drawing 1998-04-06 1 9
Abstract 1996-10-22 1 20
Description 1996-10-22 9 461
Claims 1996-10-22 3 106
Drawings 1996-10-22 4 121
Abstract 1998-08-05 1 23
Description 1998-08-05 9 449
Claims 1998-08-05 3 106
Cover Page 1999-09-30 1 40
Cover Page 1996-09-30 1 13
Description 1996-09-30 9 327
Abstract 1996-09-30 1 14
Claims 1996-09-30 3 74
Drawings 1996-09-30 4 71
Cover Page 1998-04-06 1 40
Claims 2004-10-14 3 104
Claims 2005-08-01 3 105
Representative Drawing 2005-09-14 1 18
Cover Page 2006-01-04 1 44
Fees 2001-09-10 1 22
Prosecution-Amendment 2005-02-21 3 100
Fees 1999-09-24 2 128
Fees 2000-09-26 2 136
Fees 2002-09-27 1 68
Correspondence 2002-07-03 1 64
Correspondence 2003-07-16 1 32
Fees 2003-07-16 1 50
Prosecution-Amendment 1998-08-05 17 724
Assignment 1996-09-30 3 155
Prosecution-Amendment 2003-07-18 1 31
Correspondence 1996-10-22 12 841
Correspondence 2003-09-04 1 10
Fees 1998-09-24 2 115
Prosecution-Amendment 2004-04-30 3 90
Prosecution-Amendment 2004-10-14 4 139
Fees 2004-10-14 1 26
Prosecution-Amendment 2005-08-01 8 285
Fees 2005-08-01 1 61
Correspondence 2005-11-22 1 90
Fees 2006-09-19 1 60
Fees 2007-09-14 1 60
Fees 2008-09-04 1 61