U.S. patent number 3,767,022 [Application Number 05/029,744] was granted by the patent office on 1973-10-23 for return spring key stem boot.
This patent grant is currently assigned to The Singer Company. Invention is credited to Cecil G. Olson.
United States Patent |
3,767,022 |
Olson |
October 23, 1973 |
RETURN SPRING KEY STEM BOOT
Abstract
A stem boot for providing breakaway feel for individual keys of
a manually actuated keyboard.
Inventors: |
Olson; Cecil G. (San Francisco,
CA) |
Assignee: |
The Singer Company (New York,
NY)
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Family
ID: |
21850653 |
Appl.
No.: |
05/029,744 |
Filed: |
April 24, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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518426 |
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Current U.S.
Class: |
400/481; 178/17C;
200/302.2; 235/145R; 400/477; 74/18.2; 200/293; 200/521; 250/229;
400/490 |
Current CPC
Class: |
B41J
5/26 (20130101); H01H 13/50 (20130101); B41J
5/08 (20130101) |
Current International
Class: |
B41J
5/00 (20060101); B41J 5/26 (20060101); H01H
13/50 (20060101); B41j 005/08 () |
Field of
Search: |
;197/98 ;74/18.2,17.8
;178/17 ;340/365 ;250/220,229,219 ;235/145 ;200/159,168 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burr; Edgar S.
Parent Case Text
STATEMENT OF RELATED CASES
This application is a continuation of U.S. patent application Ser.
No. 518,426, filed Jan. 3, 1966, now abandoned.
Claims
What is claimed is:
1. A spring-like stem boot adapted to surround a reciprocable stem
coupled to a key element for providing a restoring force urging
said key element toward a rest position, said stem boot comprising
a hollow, resilient member including:
a cylindrical base portion adapted to be secured to a mounting
means,
a top portion having a central bore adapted to be coupled to said
stem, the outer diameter of said top portion being smaller than the
inner diameter of said cylindrical base portion,
a frusto-conical intermediate portion forming a first integral
junction at the largest diameter portion thereof with a first end
of said cylindrical base portion and forming a second integral
junction at the smallest diameter portion thereof with said top
portion, the thickness of said frusto-conical portion increasing
along the length thereof from said first junction to said second
junction,
said recited characteristics of said cylindrical base and
frusto-conical portions of said stem boot providing a nonlinear
restoring force exhibiting increasing resistance with increased
displacement of said key element up to a maximum and thereafter
exhibiting decreasing resistance to increased displacement of said
key element,
said recited structure of said stem boot enabling said stem boot to
function as a toggle having two stable states, one of which is said
rest position, and
stop means associated with said stem boot for preventing
displacement of said key element past the equilibrium of said
toggle.
2. The stem boot of claim 1 wherein said frustoconical portion and
the axis of said cylindrical portion are formed at an angle
enabling the formation of hoop stresses at said first junction when
said key element is actuated.
3. The stem boot of claim 2 wherein said angle is in the range from
30.degree. to 35.degree..
4. The stem boot of claim 1 wherein the angle between the outer
surface of said frusto-conical portion and the axis of said
cylindrical portion is substantially 30.degree. and the angle
between the inner surface of said frusto-conical portion and said
axis is substantially 35.degree..
5. The stem boot of claim 1 wherein said stop means comprises an
upturned annular flange arranged circumferentially of said
cylindrical base portion and adapted to abut the advancing edge of
said key element.
6. A return spring for biasing a pushbutton supporting plunger away
from a guide base relative to which the plunger is movable along a
line substantially normal to the base, the spring comprising a
tubular element fabricated of a resilient elastomeric material, the
element being arranged for disposition coaxially of the plunger
between the base and the pushbutton and normally configured to
define first and second opposite coaxially aligned terminal
cylindrical portions and a central frustroconical portion
integrally connected circumferentially of its opposite ends with
the adjacent ends of the first and second cylindrical portions
respectively, the first cylindrical portion having an inner
diameter sized to mate with the plunger adjacent the pushbutton end
thereof, the inner diameter of the second cylindrical portion being
greater than the outer diameter of the first cylindrical portion,
the second cylindrical portion being arranged for support by the
base circumferentially of the plunger and having sufficient length
that the end thereof connected to said frusto-conical portion is
deformable radially outwardly to enable said frusto-conical portion
to deform into a planar state between said first and second
cylindrical portions in response to a compressive load applied
axially of the tubular element by depression of said plunger, said
frusto-conical portion deforming past said planar state with a snap
action in response to additional compressive loads.
7. Apparatus according to claim 6 in which the wall of the
frusto-conical portion of the element decreases in thickness from
the end thereof connected to the first cylindrical portion to the
end thereof connected to the second cylindrical portion.
8. Apparatus according to claim 6 wherein the end of the second
cylindrical portion opposite from the frusto-conical portion is
joined to a flat sheet of the resilient material peripherally of an
aperture in the sheet.
Description
This invention relates to keyboards that utilize unique energy path
patterns to identify actuated keyboard key elements, and more
particularly to inexpensive and reliable key mechanisms for such
keyboards that can also provide a "breakaway feel" when such key
mechanisms are manually actuated.
One object of this invention is to provide an improved keyboard
device.
Another object of this invention is to provide a keyboard which is
economical to fabricate and reliable in operation.
A still further object of this invention is a keyboard device
having a plurality of key mechanisms, each of which provide a
"breakaway feel" when they are manually actuated.
A keyboard device utilizing this invention includes a plurality of
key mechanisms, each including a stem portion having a keyboard key
element at one end thereof and a code card located a distance away
from the key element. Each code card has a first portion including
a plurality of channels or openings thereon with the channels on
the first portion of each code card being juxtaposed the channels
on the first portion of the other code cards so as to form a
plurality of passageways or paths which extend through or along the
plurality of code cards. Each code card also has a second portion
adjacent the first portion with predetermined ones of said channels
on said first portion also appearing on, or extending into, the
second portion. Mounting means are provided for the plurality of
key mechanisms that permit each code card to be displaced with
respect to the plurality of passageways by depressing the
associated keyboard key element so that the absence of at least one
channel, or path, on the second portion of the associated code card
interrupts at least one passageway to provide a pattern of
passageway interruptions that identify the depressed keyboard key
element.
In a variation of the above-noted keyboard, the plurality of key
stems and code cards comprise a unitary structure which includes an
elongated primary support member having a plurality of juxtaposed
elongated secondary support members emanating from the length
thereof, with each secondary support member having one of the
plurality of juxtaposed code cards and one of the key stems as a
part thereof. Each secondary support member has a portion of its
length adjacent the primary support member reduced in
cross-sectional area to permit the secondary support members to be
partially rotatable around the primary support member.
In accordance with the present invention, a unique stem boot
surrounds each of the key stems and is located intermediate the
keyboard key element and mounting means which supports the key
stem. The stem boot includes a hollow elastic member having a
portion of its length adjacent the mounting means being cylindrical
and at least a portion of its remaining length being a conic
section, with the smallest circumference portion of the conic
section being adjacent the key element and the largest
circumference portion of the conic section forming a junction with
one end of the cylindrical section. The angle of the conic section
with respect to the cylindrical poirtion is such that hoop stresses
occur at the junction of the cylindrical and conic sections when
the associated key element is depressed. Also, the thickness of the
conic section increases along its length from the junction of the
cylindrical section with the conic section to the smallest
circumference portion of the conic section. This unique stem boot
provides a "breakaway feel" when the keyboard key elements are
manually actuated which enables high manual operating speeds to be
obtained with the keyboard.
This invention, as well as other objects, features, aspects and
advantages thereof, will be readily apparent from consideration of
the following detailed description relating to the accompanying
drawings in which:
FIG. 1 is a top plan view, partially in section, of a keyboard
device, in accordance with the present invention;
FIG. 2 is a cross-sectional elevational view taken along the plane
indicated by the line 2--2 of FIG. 1, which illustrates the code
cards and key stems of the keyboard key mechanisms comprising the
subject invention;
FIG. 2A is a partial cross-sectional elevational view similar to
FIG. 2, but showing the relative positions of the code cards after
one of the keyboard key elements has been depressed;
FIG. 3 is an exploded, perspective view which more clearly
illustrates the keyboard key mechanisms of FIGS. 1 and 2;
FIGS. 4A, 4B and 4C are partial cross-sectional views for
illustrating a unique key stem boot in accordance with the present
invention, while the associated keyboard key element is being
depressed;
FIG. 5 illustrates a force versus distance diagram for conventional
spring-loaded keyboard key elements, as compared to the force
required to actuate a keyboard key element which utilizes the
unique key stem boot of this invention; and
FIG. 6 is a perspective view of a unitary molded structure which
contains a plurality of keyboard key mechanisms.
Referring now to the drawings, wherein like reference characters
designate like or corresponding parts throughout the several views,
there is illustrated in FIGS. 1 and 2 a keyboard device according
to this invention which comprises an elongated hollow housing or
mounting means 11 for a plurality of keyboard key mechanisms. The
housing 11 includes a base portion 12 to which an enclosure 13 is
secured by any suitable means, such as screws 14. Each key
mechanism contains a stem 15 which is slidably supported by the
housing 11 and at least partially contained therein. One end of
each stem protrudes through the enclosure portion 13 and is adapted
to receive a keyboard key element, or key top, 16 at the end
thereof. Surrounding each key stem intermediate the enclosure
portion 13 and the key element 16 is a hollow elastic stem boot 17
which is described in detail hereinbelow. The other end of each
stem passes through the base portion 12 of the housing 11. As
illustrated by FIG. 1, each stem has a cross-section that prevents
its rotation within the housing 11 and since each end of the stems
15 is slidably supported by the housing 11, each stem can be
accurately positioned within the housing 11.
Each stem includes as a part thereof a flat rectangular portion or
code card 18. Each code card contains a first, or bottom, portion
which includes a plurality of channels, or openings, 19. The code
cards of each stem are juxtaposed, or positioned, adjacent the code
cards of the other stems, so that the plurality of openings 19 are
juxtaposed to form a plurality of passageways, or paths, which are
substantially normal to the plurality of code cards. As illustrated
by FIG. 1, the lateral distance separating the plurality of
juxtaposed code cards is not critical and, therefore, need not be
uniform. In one embodiment of the present invention which was
constructed, this spacing varied from three-sixteenths of an inch
to three-eighths of an inch. Each stem and its associated code card
can be a unitary structure which can be molded from any suitable
material, such as a plastic. The unitary structure can also be
stamped, pressed, etc., and can also be fabricated from sheet
metal. Located above and adjacent the channels, or openings, 19, on
the first portion of each code card, is a second portion into which
selected ones of the openings, or channels, on the first portion
may extend. These openings, or channels, in the second portion of
the code card, or the absence thereof, identify the alphanumeric or
other values given to the associated keyboard key element. The
channels, or openings, which extend into the second portion of each
code card may be formed when each stem and associated code card is
molded. Alternatively, the second portion of each code card may
contain a plurality of knockout portions 21 adjacent the openings,
or channels, 19, on the first portion of each code card which
enables the coded second portion of each code card to be formed by
removing the appropriate knockout portions 21. Although the
openings on the lower portion of each code card are illustrated as
being enclosed, it is to be understood that an enclosed opening is
not necessary and that a plurality of ducts, channels or grooves
along the bottom portion of the first portion of each code card
will suffice to form the plurality of passageways, or paths, which
extend through the plurality of juxtaposed code cards.
Located at one end of the plurality of juxtaposed code cards is an
energy source, as illustrated in FIG. 1, which may comprise a light
source 26 and reflecting means 27 for forming the light generated
by the source 26 into a rectangular bar of light. This light source
is located adjacent the first portion of the nearest code card such
that the plurality of code cards have their first portion normal to
the rectangular bar of light formed by the light source 26 and
reflecting means 27. Therefore, the plurality of passageways that
extend along the plurality of code cards constitute a plurality of
energy paths for the light produced by the source 26. Located at
the other end of the plurality of code cards and adjacent the
openings on the nearest code card are a plurality of energy pickup
devices, such as photo cells 25, each of which is associated with
one of the energy passageways which extend through the first
portion of the plurality of code cards.
The plurality of energy paths, or passageways, extending through
the plurality of juxtaposed coded cards are clearly illustrated by
FIG. 3, which is an exploded perspective view of several of the
keyboard key mechanisms illustrated in FIGS. 1 and 2. Reference to
FIG. 3 shows that the rectangular bar of light formed by the light
source 27 and focusing, or reflecting, means 26, is directed to the
first portion of each code card and that the plurality of openings
or channels on the first portion of the juxtaposed code cards
divide the light into a plurality of energy paths indicated by the
reference character 20. These energy paths extend along and through
the plurality of juxtaposed code cards and terminate at photo cells
25.
Each stem and associated code card is mounted within the keyboard
housing 11 such that it can only be moved substantially normal to
the plurality of energy or light paths 20 that extend through the
plurality of code cards. Accordingly, when a keyboard key element
is depressed, its associated stem moves downward, causing its code
card to be moved normally, or substantially perpendicular to, the
plurality of energy paths. This causes the second portion of the
selected code card to be in the position formerly occupied by the
first portion of the associated code card. This causes the absence
of openings, or channels, on the second portion of the depressed
code card to interrupt one or more of the energy paths which extend
through the plurality of juxtaposed code cards, as is illustrated
by FIG. 2A, wherein it is shown that only one energy path 20
remains, due to the single opening, or channel, 19' extending into
the second portion of the selected code card. As described above,
the number of openings, or channels, on the second portion of each
code card identify the alphanumeric, or other value, given to the
associated keyboard key element. Accordingly, depression of one of
the keyboard key elements interrupts the plurality of energy, or
light, paths 20 which extend through the plurality of juxtaposed
code cards in such a manner that the pattern of interruptions
identify the depressed keyboard key element, by causing
predetermined ones of the pickup devices or photo cells 25 not to
be energized. Generally, the output of the pickup, or photo cells,
25 is coupled to a matrix (not shown), or other suitable decoding
device, whereby the patterns of energy interruptions are
transformed into a code suitable for associated circuitry or
equipment.
FIGS. 1 through 3 illustrate a typewriter keyboard device wherein
the keyboard key elements 16 represent typewriter alphanumeric
values or functional values, such as the space bar 22. The present
invention, however, is not limited to these values inasmuch as
other functions, or values, may be coded on the code cards 18. For
example, the irregular spacing of the code cards 18, as illustrated
by FIG. 1, permits other code cards to be inserted therebetween,
which other code cards may have other typewriter functional values,
such as typewriter tab set, tab clear, etc., and other
nontypewriter functions, such as program changing and modification,
etc. Depression of two or more keyboard key elements simultaneously
can be prevented by incorporating a mechanical interlock device
(not shown) with the keyboard device of FIGS. 1 through 3, such
mechanical interlocks being well-known in the art. The keyboard
device may also include an electronic interlock, whereby the use of
a sufficient number of openings, or channels, 19 on the first
portion of the code cards enables the value codes assigned to each
card to be designed such that the depression of two or more key
elements create a pattern of energy path interruptions which do not
correspond to any single key element and is, therefore, rejected as
being an error corresponding to the depression of two or more key
elements.
FIG. 5 represents a force versus distance or deflection diagram
which illustrates the minimum force required to actuate a
conventionally spring-loaded keyboard key element and the minimum
force required to actuate a keyboard key mechanism in accordance
with the present invention. The ordinate axis of this diagram
represents units of force applied to a keyboard key element and the
abscissa of the diagram is in units of distance the keyboard key
element travels in order to be actuated. The curve 30, which
illustrates the minimum force required to actuate a conventionally
spring-loaded keyboard key element, is substantially linear, and
the operator actuating such a key element receives no indication or
feel that the key is actuated until the point 31 is reached, at
which time the key element is fully depressed, as illustrated by
the diagram of FIG. 5. The curve 32, on the other hand, which shows
the minimum force required to actuate the key mechanism of this
invention, shows that the force required to actuate the key
mechanism increases until the point 33 is reached, after which the
force required to actuate the key mechanism decreases until the
point 34 is reached, at which time the key element has been
selected, or actuated.
After the point 33 is reached, the operator depressing the key
element can feel the reduced force required to fully actuate the
key mechanism, such that the reduced actuating force produces a
"breakaway feel" which permits the keyboard to be manually operated
at a higher rate of speed than a conventionally spring-loaded
keyboard. This is so because the feel imparted to the actuating
finger of the operator at the point 33 enables the operator to
mentally commence the necessary physical motions required to select
the next keyboard key element. This "breakaway feel" is present in
electric typewriters and is highly desirable in other keyboard
devices and has only been obtained heretofore in the prior art by
relatively expensive and complex mechanisms associated with
keyboard key mechanisms.
A "breakaway feel" is obtained in accordance with the present
invention by the hollow, elastic, cylindrical boot 17 illustrated
in FIG. 2. This boot surrounds the key stem 15 protruding from the
enclosure 13 and is located intermediate the keyboard key element
16 and the enclosure, or mounting portion, 13. FIGS. 4A, 4B and 4C
illustrate this unique stem boot in cross-section for various
degrees of key element depression. FIG. 4A illustrates the stem
boot when the key 16 is in its normal, or rest, position, and shows
the stem boot as comprising a cylindrical section which is
adjacent, or secured to, the enclosure 13 and a tapered or conic
section, the smallest circumference portion of which is adjacent
the keyboard key element 16. The largest circumference portion of
the conic section forms a junction with the end of the cylindrical
section remote from the enclosure 13. The thickness of the tapered
or conic section increases along its length from the junction of
the conic section with the cylindrical section to the end of the
conic section adjacent the key element 16. In accordance with one
embodiment of the boot which was constructed, the inside surface of
the conic section was at a 30.degree. angle with respect to the
longitudinal axis of the cylindrical section or the key stem which
the stem boot surrounds, the outside surface of the conic section
was at a 35.degree. angle with respect to the longitudinal axis of
the cylindrical section of the boot and the longitudinal axis of
the key stem and the key stem boot 17 was constructed from an
elastic material, such as silicone rubber, which was molded into
the above described shape.
When the key element 16 is initially depressed, the conic section
causes hoop stresses to occur at the junction of the conic and
cylindrical sections, such that the boot at this junction tends to
bulge outwardly, as illustrated by FIG. 4B. These hoop stresses
cause stresses to back up into the conic section. However, due to
the increasing thickness of the conic section, the conic section
does not bend or wrinkle at a point along its length adjacent to
the key element 16. Rather, any bending of the conic section of the
boot takes place adjacent the junction of the conic and cylindrical
sections as illustrated in FIG. 4B. When the key element is fully
actuated or depressed, corresponding to the point 34 in FIG. 5, the
stem boot has a cross-section as illustrated in FIG. 4C. When in
the position illustrated in FIG. 4C, the stem boot has an upward
resilient force that causes the key mechanism to return to its
normal, or rest, position when the operator releases the key
element. If the stem boot were to be further depressed downwardly
beyond that illustrated in FIG. 4C, the boot would pass an
equilibrium point after which the boot would remain depressed after
operator actuating force was released. In other words, the stem
boot 17 has the characteristics of a toggle in that it has two
stable states, one being illustrated by FIG. 4A and another being
when it is more fully depressed downwardly than that illustrated in
FIG. 4C. In order to prevent the equilibrium point from being
reached, the key element 16 has a side portion 23 which limits, or
stops, the downward movement of the key element to a position
before the equilibrium point of the boot is reached or exceeded. As
illustrated by FIGS. 4A, 4B and 4C, the boot itself may contain a
raised portion 28 which limits the downward movement of the key
element to prevent the equilibrium point of the boot toggle from
being reached. The minimum force required to actuate, or depress,
the stem boot of FIGS. 4A, 4B and 4C is illustrated by the curve 32
of FIG. 5, which shows that the minimum force breaks away at the
point 33 to provide the highly desirable "breakaway feel" which
enables a relatively high manual operating speed of the keyboard
device.
The stem and associated code card of each of the keyboard key
mechanisms may, as described hereinabove, be molded from a suitable
material, such as plastic, and is, therefore, a very simple and
economical structure to fabricate. FIG. 6 illustrates a partial
perspective view of another embodiment of the present invention,
wherein the plurality of stems and code cards comprising a
plurality of keyboard key mechanisms are a unitary molded structure
which may be formed from any suitable material, such as a plastic.
Reference to FIG. 6 shows that such a unitary structure includes an
elongated primary support member 35 having a plurality of
juxtaposed elongated secondary support members 36 emanating from
the length thereof. Each secondary support member contains one of
the above-described stems 15 and code cards 18 such that the
plurality of code cards are normally juxtaposed to form the
plurality of energy passages, or paths, as described above. In
order to permit each code card to be partially movable or rotatable
around the primary support member 35, the cross-sectional area of
each secondary support member 36 has a portion of its length
adjacent the primary support member reduced in cross-sectional
area. The amount of stress, or deflection, which takes place near
the junction of the secondary support member with the primary
support members can be varied by varying the distance of the code
cards from the primary support member for a given displacement of
the code cards. In this manner, it is relatively easy to ensure
that constant and continuous partial deflection of the code cards
around the primary support member will not cause a failure where
the secondary support members join and become a part of the primary
support member. As with the code card sections previously
described, the openings, or channels, in the second portion of each
code card can be molded at the time the entire unitary structure is
molded, or knockout portions may be molded thereon to permit easy
coding of the second portion of the code cards after molding the
entire unitary structure.
What has been described is a simple and economical keyboard device
which provides a plurality of energy paths, or passageways, and
means for providing a pattern of passageway interruptions when a
keyboard key element is depressed that identify the actuated key
element. Simple and economical means are also provided that give
the keyboard key elements a "break-away feel" when actuated, that
enables a high manual operating speed of the subject keyboard.
It should be understood, of course, that the foregoing detailed
description relates only to preferred embodiments of the present
invention, and that numerous modifications or alterations may be
made therein without departing from the spirit and scope of the
invention, as set forth in the appended claims.
* * * * *