U.S. patent number 3,780,237 [Application Number 05/297,721] was granted by the patent office on 1973-12-18 for keyboard switch assembly with multi-sectional key actuator.
This patent grant is currently assigned to Chomerics, Inc.. Invention is credited to John G. Coulter, Richard E. Seeger, Jr..
United States Patent |
3,780,237 |
Seeger, Jr. , et
al. |
December 18, 1973 |
KEYBOARD SWITCH ASSEMBLY WITH MULTI-SECTIONAL KEY ACTUATOR
Abstract
A keyboard array including a board having a conductive pattern
thereon, a resilient conductive layer, a first or external plunger
supported in a housing and slidable therein, a second or internal
plunger supported in the external plunger and first resilient
biasing means urging the first plunger towards the housing and away
from the conductive layer and a second resilient biasing means
urging the second plunger away from the first plunger and towards
the conductive layer.
Inventors: |
Seeger, Jr.; Richard E.
(Topsfield, MA), Coulter; John G. (Reading, MA) |
Assignee: |
Chomerics, Inc. (Woburn,
MA)
|
Family
ID: |
23147467 |
Appl.
No.: |
05/297,721 |
Filed: |
October 16, 1972 |
Current U.S.
Class: |
200/5A; 200/511;
200/517 |
Current CPC
Class: |
H01H
13/705 (20130101) |
Current International
Class: |
H01H
13/70 (20060101); H01H 13/705 (20060101); H01h
017/14 (); H01h 003/12 () |
Field of
Search: |
;200/1R,5R,5A,16,17R,153R,159,166PC,172R,172A |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
3300600 |
January 1967 |
Blomquist et al. |
3493705 |
February 1970 |
Noll et al. |
3408464 |
October 1968 |
Earleywine, Jr. et al. |
|
Primary Examiner: Scott; J. R.
Claims
We claim:
1. In a keyboard array including an insulator board supporting a
circuit having at least one electrically conductive contact
provided on one surface of said board, a resilient conductive layer
means positioned to make contact with said contact upon application
of a force thereto, and means separating said conductive layer
means from said contact and having a window therethrough which said
conductive layer may extend to make contact with said electrical
contact, the improvement comprising an external plunger having a
bore, an internal plunger slidably movable within a bore formed in
an external plunger, a housing slidably supporting said external
plunger, means coupling said housing to said board, first resilient
biasing means biasing said external plunger away from said
conductive layer means, second resilient biasing means biasing said
internal plunger towards said conductive layer, said internal
plunger positioned to apply a force against said conductive layer
means to make electrical contact with said contact upon the
application of a force applied to said external plunger, a key
mounted on said external plunger and snap members provided on said
external plunger to confine a portion of said internal plunger
within said bore thereof.
2. In a keyboard array according to claim 1 in which said plunger
portion positioned in said bore has tapered slots to permit easy
entry into said bore.
3. In a keyboard array according to claim 2 in which vent channels
are provided to facilitate movement of said internal plunger in
said bore.
4. In a keyboard array according to claim 3 in which means are
provided on both of said plungers for locating said second biasing
means and wherein means are provided on said housing and external
plunger for locating said first biasing means.
5. In a keyboard array including an insulator board supporting a
circuit having at least one electrically conductive contact
provided on one surface of said board, a resilient conductive layer
means positioned to make contact with said contact upon application
of a force thereto, and means separating said conductive layer
means from said contact and having a window therethrough which said
conductive layer may extend to make contact with said electrical
contact, the improvement comprising an external plunger, an
internal plunger slidably movable within a bore formed in an
external plunger, a housing slidably supporting said external
plunger, means coupling said housing to said board, first resilient
biasing means biasing said external plunger away from said
conductive layer means, second resilient biasing means biasing said
internal plunger towards said conductive layer, said internal
plunger positioned to apply a force against said conductive layer
means to make electrical contact with said contact upon application
of a force applied to said external plunger, a key mounted on said
external plunger, and said array comprises a sandwich of said
board, said circuit having said conductive contact on said board,
said insulator layer having a window therethrough in alignment with
at least a portion of said contact,said resilient conductive
plastic layer means positioned on said insulator layer and said
housing mounted with said plunger mounted on top of said conductive
layer means.
6. In a keyboard array according to claim 5 in which an insulator
pad having a window therethrough in alignment with at least a
portion of said window of said insulator layer and in which said
housing has mounting portions which extend through holes formed in
said pad, conductive layer, insulator layer means and board for
joining said sandwich together.
7. In a keyboard array according to claim 2 in which said external
plunger and said housing are provided with guide means for
preventing rotation of said external plunger.
8. A key construction comprising a housing, a first plunger having
at least a portion slidably movable within said housing and having
a key attached thereto, a second plunger having a portion slidably
movable within a portion of said first plunger, first resilient
biasing means positioned between said plungers to urge them away
from each other, said second plunger includes a portion having
tapered slots and wherein said first plunger has resilient
projections, said slots pushable over said projections to snap said
second plunger into said first plunger and retain said second
plunger within said first plunger for slidable movement therein.
Description
STATEMENT OF INVENTION
This invention is directed to a new and improved keyboard key or
switch construction and is more particularly directed to a new and
improved switch or key actuator for causing a conductive layer to
engage an electrically conductive pathway upon depression
thereof.
The actuating means of this invention is useable in place of the
switch actuating means disclosed in copending U.S. Pat.
applications, Ser. No. 145,212 filed May 20, 1971 by Richard E.
Seeger,Jr. and George T. Hodgson,Jr. now U.S. Pat. No. 3,705,276
and Ser. No. 154,752 filed June 12, 1971 by Richard E. Seeger,Jr.
and William J. Lynn now U.S. Pat. No. 3,721,778. The entire
disclosure of these patent applications being incorporated herein
by reference hereto.
The actuating means of the present invention permits the
construction of a simple and highly reliable keyboard at low cost.
The actuating means is adapted to be constructed of primarily
molded parts which when placed together form a modular unit. The
modular units may then be individually mounted on a circuit board
construction,as shown in the foregoing mentioned applications, in
any number required by the application intended.
BRIEF DESCRIPTION OF THE INVENTION
The keyboard array of this invention includes a printed circuit
board having circuit pathways or contacts thereon, a mask having a
window therethrough in alignment with a portion of one or more of
the circuit pathways, a conductive layer positioned over the mask
and adapted to extend through the hole into engagement with at
least one of the electrical pathways upon the application of a
force thereto and also adapted to spring back from the electrical
pathways out of electrical contact upon removal of the force and at
least one actuator modular unit adapted to be coupled to the board
and having an internal plunger member slidably housed with exterior
plunger member and adapted to apply a force against the conductive
layer, the exterior plunger member supported in a housing coupled
to the board, first resilient biasing means urging the external
plunger away from the conductive layer and second resilient biasing
means urging the internal plunger towards the conductive layer and
allowing the internal plunger to retract into the external plunger
to prevent the application of an excess force against the
conductive layer. In addition, there is provided snap means forming
part of the external plunger for retaining part of the internal
plunger within a bore of the external plunger and an insulator
layer positioned on the conductive layer and having a window
therethrough to permit the internal plunger to contact the
conductive layer, the housing and first resilient biasing means
resting upon this insulator layer in the preferred embodiment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of a keyboard with parts cutaway showing the
invention;
FIG. 2 is a sectional view taken along line 2--2 in FIG. 1;
FIG. 3 is a sectional view similar to FIG. 2 with the switch in the
actuated position;
FIG. 4 is a sectional view taken along line 4--4 in FIG. 2;
FIG. 5 is a sectional view taken along line 5--5 in FIG. 2; and
FIG. 6 is a side view of a portion of the internal plunger.
BRIEF DESCRIPTION OF THE INVENTION
Reference should now be had to FIGS. 1-5 for the detailed
description of the invention. At 9 there is shown a keyboard which
includes an outer decorative frame 10 in which there is positioned
the operating parts of the keyboard. See U.S. Pat. No. 3,705,276
for an illustration of suitable frame mounting. The operating parts
include an insulator board 11 (e.g., Bakelite, Formica) of the
conventional type used in printed circuit applications and having a
plurality of mounting holes 11a formed therethrough.
At 12 there is provided electrical contact means or electrical
pathways formed on the board using conventional printed circuit
etching techniques wherein copper is etched away or the contact
means may be formed by other conventional screening techniques
wherein an electrically conductive coating is laid down to form a
circuit pattern. Various circuit patterns are shown in the
aforementioned patent applications which are incorporated
herein.
At 13 there is shown an insulator layer, for example of plastic
such as sold under the trademark Mylar and having a window 13a
extending therethrough in line with at least a portion of the
electrical contact means 12.
A resilient electrically conductive layer or sheet is shown at 14
and is of a type of a material which may be forced through the
window 13a into contact with the contact means 12 with the
application of a force thereto (see FIG. 3) and then spring back to
the position shown in FIG. 2 when the force applied thereto is
removed. Various materials may be used as the conductive layer as
set forth in the aforementioned referred to applications with the
preferred material being a conductive plastic preferably formed of
silicone rubber (rubber is defined as a plastic in the context used
herein) filled with silver flakes, i.e., between 10 to 80 percent
by volume.
At 15 in the drawing there is provided a mounting pad or layer 15
of insulating material i.e., of plastic such as sold under the
trademark Mylar. The pad 15 is provided with a window 15a
therethrough in alignment with at least a portion of the window
13a.
Each of the layers 13, 14 and 15 are also provided with mounting
holes 13b, 14b and 15b respectively, positioned in alignment with
hole 11a formed in the board 11. At 20 there is shown a plurality
of modular key units or actuating units adapted to be individually
mounted on the board 11. Each of the units 20 comprises a key
portion 21 upon which indicia e.g., numbers or letters (see FIG. 1)
may be applied.
The key portion 21 is mounted on a first or external plunger or
actuating member 22 which includes a bore 22a having resilient snap
members 22b at the bore 22a opening. The plunger 22 is positioned
for slidable movement within a housing 25 and is preferably
prevented from rotating by guide means such as tongues 22e
positioned in channels 25d. The upper limit of movement of the
plunger 22 within the housing 25 is determined by a shoulder 25a
formed within the housing.
The housing 25 is provided with mounting members 25b which extend
through layer 11,13,14 and 15 holes 11b, 13b, 14b and 15b
respectively, and are provided with retaining heads 25c.
In the preferred construction of the housing 22, it is constructed
of plastic with the members 25b being initially rods. The plastic
used for housing is selected of a plastic material e.g.,
polypropylene, nylon, which may be softened and shaped to form the
retaining heads after the assembly is formed.
Nuts may also be used to mount the units 20 on the board 11 by
forming threads at the end of the members 25b. At 26 there is shown
a second or internal plunger or actuating member which includes
portion 26a slidably movable within the bore 22a and retained
therein by the snap members 22b.
The snap members 22b are bendable backward to permit entry of the
portion 26a, and the portion 26a is provided with tapered slots
26aa to facilitate entry of the member 26a into the bore 22a (see
FIG. 6). In order to permit slidable movement of the portion 26a
within the bore 22a without excessive force there is provided air
vents or exit channels 25d in the bore.
Extending from the plunger portion 26a is a shaft member 26b which
supports a pusher portion 26c. The pusher portion 26c is provided
with a tip which is adapted to push the conductive layer 14 through
the window 13a to make contact with the contact 12 (see FIG.
3).
In order to effect control of the plungers 22 and 26 there are
provided resilient biasing means or springs 27 and 28. The spring
27 biases the first plunger 22 against the housing shoulder 25a and
away from the conductive layer and is positioned at one end on the
pad 15 and is located by the interior of the member 22.
Spring 28 is positioned between the first plunger 22 bottom and the
pusher portion 26c and urges the plunger 26 towards the conductive
layer and is located at its ends about a cylindrical tier 22d
formed on the plunger 22 and a cylindrical tier 26d.
The spring 28 acts as an overload spring to permit the member 26 to
move rearwardly if an overload force is applied to the key 21. This
is accomplished by selecting the spring 28 so that after member 26
has bottomed additional force applied to the key and the first
plunger causes the plunger 26 to overcome the force applied by the
spring 28.
In addition, the bore is made longer than the member 26a so that
rearward motion is possible. In operation the key 21 is pressed to
cause the first plunger 22 to move the second plunger 26 therewith
to cause the conductive layer to make contact with the contact 12.
If the conductive layer is grounded as disclosed in the
aforementioned U.S. Pat. No. 3,721,778 and the contact is high (+)
then a circuit will be completed and the current will flow.
Alternatively the electrical contact 12 may be segmented as shown
in the aforementioned U.S. Pat. Nos. 3,705,276 and 3,721,778 and
electrical contact may then be made between the segments to
complete a circuit.
In order to make electrical contact with the segments or conductive
layer from external circuitry, pins or connectors are employed as
shown in the aforementioned patent applications.
* * * * *