U.S. patent application number 10/114151 was filed with the patent office on 2003-10-02 for impact absorbing system for a flat switch panel.
This patent application is currently assigned to DURASWITCH. Invention is credited to Shepard, Steven Yale, Van Zeeland, Anthony J..
Application Number | 20030183659 10/114151 |
Document ID | / |
Family ID | 28453746 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030183659 |
Kind Code |
A1 |
Van Zeeland, Anthony J. ; et
al. |
October 2, 2003 |
Impact absorbing system for a flat switch panel
Abstract
An impact absorbing system for a flat switch panel has an impact
spacer. The impact spacer, a rigid layer that is fixed to an
energy-absorbing layer, attaches to the top surface of a flat
switch panel just under the overlay. During a condition of switch
abuse, the impact absorbing system disperses the energy from a high
impact actuation force over a large area of the rigid layer, which
in turn causes a large volume of energy-absorbing layer material to
be deformed, directing the otherwise damaging impact away from a
raised part of the switch that normally accepts a user provided
actuation force. Preferably there is an embossed area in the rigid
layer and a pip on the raised part of the switch, both improving
the function and tactile feedback of the switch. The most preferred
embodiment includes a polycarbonate backer on the bottom of the
flat switch panel to additionally protect switch components from
being damaged by a high impact actuation force.
Inventors: |
Van Zeeland, Anthony J.;
(Mesa, AZ) ; Shepard, Steven Yale; (Chandler,
AZ) |
Correspondence
Address: |
DURASWITCH
234 S. EXTENSION
SEC. 103
MESA
AZ
85210
US
|
Assignee: |
DURASWITCH
Mesa
AZ
|
Family ID: |
28453746 |
Appl. No.: |
10/114151 |
Filed: |
April 2, 2002 |
Current U.S.
Class: |
222/399 |
Current CPC
Class: |
H01H 2217/016 20130101;
H01H 2221/04 20130101; H01H 2209/01 20130101; B32B 7/022 20190101;
H01H 2231/006 20130101; H01H 13/702 20130101; H01H 2239/038
20130101; H01H 13/704 20130101 |
Class at
Publication: |
222/399 |
International
Class: |
B65D 083/00 |
Claims
What is claimed is:
1. A method of making an impact absorbing system, for use with a
flat switch panel that has at least one pushbutton switch,
comprising the steps of: fabricating an impact spacer having a
rigid layer with a top and bottom and an energy-absorbing layer
with a top and bottom; forming at least one isolation structure in
the rigid layer; attaching the bottom of the rigid layer to the top
of the energy-absorbing layer; installing the impact spacer onto
the flat switch panel so that the energy-absorbing layer is
intermediate the rigid layer and the at least one pushbutton switch
of the flat switch panel.
2. The method of claim 1 wherein the step of forming an isolation
structure in the rigid layer is characterized by embossing an area
of the rigid layer that is above the at least one pushbutton switch
of the flat switch panel.
3. The method of claim 1 wherein the step of forming an isolation
structure in the rigid layer is characterized by a forming a
supplemental rigid layer, the supplemental rigid layer having at
least one cutout that is above the at least one pushbutton switch
of the flat switch panel, the top of the rigid layer substantially
covering the supplemental rigid layer and the at least one
cutout.
4. The method of claim 1 further comprising the step of positioning
a backer on the flat switch panel such that the at least one
pushbutton switch is intermediate the backer and the impact
spacer.
5. The method of claim 1 further comprising the step of forming a
pip on the at least one pushbutton switch of the flat switch panel
such that the pip will protrude into the energy-absorbing layer of
an installed impact spacer.
6. The method of claim 1 wherein the step of installing the impact
spacer is characterized by the use of a selective adhesive layer,
the selective adhesive layer not adhering to areas on the flat
switch panel that are substantially above a pushbutton switch.
7. An impact spacer, for use with a flat switch panel that has at
least one pushbutton switch, comprising: a rigid layer with a top
and bottom; an isolation structure in the rigid layer; an
energy-absorbing layer with a top and bottom; a means of attaching
the bottom of the rigid layer to the top of the energy-absorbing
layer; and a means of attaching the bottom of the energy-absorbing
layer to the flat switch panel.
8. The impact spacer of claim 7 wherein the isolation structure is
an embossed area in the rigid layer that lies above the at least
one pushbutton switch on the flat switch panel.
9. The impact spacer of claim 7 wherein the isolation structure is
formed by making the rigid layer from at least a first and second
sheet of rigid layer material, the first sheet of the rigid layer
includes the bottom of the rigid layer and has at least one cutout
where the rigid layer covers the at least one pushbutton of the
flat switch panel, the second sheet of the rigid layer includes the
top of the rigid layer and substantially covers the first sheet and
the at least one cutout.
10. The impact spacer of claim 7 wherein the means of attaching the
energy-absorbing layer to the flat switch panel is by a selective
adhesive layer, the selective adhesive layer not adhering to areas
on the flat switch panel that are substantially above a pushbutton
switch.
11. An impact absorbing system, for use with a pushbutton switch
having a magnetically-coupled armature, comprising: an impact
spacer having a rigid layer with a top and bottom and an
energy-absorbing layer with a top and bottom; a means of attaching
the bottom of the rigid layer to the top of the energy-absorbing
layer; a means of attaching the bottom of the energy-absorbing
layer to a top surface of the pushbutton switch;
12. The impact absorbing system of claim 11 wherein the rigid layer
includes an isolation structure.
13. The isolation structure of claim 12 wherein the isolation
structure is an embossed area of the rigid layer that is at least
partially above the pushbutton switch.
14. The isolation structure of claim 12 wherein the isolation
structure includes at least a first and second sheet of rigid layer
material; the second sheet is a supplemental rigid layer, the
supplemental rigid layer having a cutout that is above the
pushbutton switch; the first sheet substantially covers the
supplemental rigid layer and the cutout.
15. The impact absorbing system of claim 11 wherein the
magnetically-coupled armature has a crown that protrudes through an
aperture in a sheet magnet coupler layer of the pushbutton switch,
the crown further comprising a pip that protrudes into the
energy-absorbing layer of the impact absorbing system.
16. The impact absorbing system of claim 15 wherein the rigid layer
includes an isolation structure.
17. The impact absorbing system of claim 16 further comprising a
backer and a means of attaching the backer to the pushbutton switch
so that the pushbutton switch is intermediate the impact spacer and
the backer.
18. The impact absorbing system of claim 11 further comprising a
backer and a means of attaching the backer to the pushbutton switch
so that the pushbutton switch is intermediate the impact spacer and
the backer.
19. The impact absorbing system of claim 11 wherein the means of
attaching the bottom of the energy-absorbing layer to a top surface
of the pushbutton switch is by a selective adhesive layer, the
selective adhesive layer not providing a means of attaching the
energy-absorbing layer to an area of the pushbutton switch that is
at least partially above the armature.
20. The impact absorbing system of claim 17 wherein the means of
attaching the bottom of the energy-absorbing layer to a top surface
of the pushbutton switch is by a selective adhesive layer, the
selective adhesive layer at least not extending over an area that
is above the crown of the magnetically-coupled armature.
Description
BACKGROUND OF THE INVENTION
[0001] Numerous devices are operated when a user presses a
pushbutton located on a flat switch panel. Increasingly, such
devices are set up at locations that are not monitored, such as ATM
machines and gas pumps. If a single switch on a device fails, the
entire device must be shut down until the failed switch can be
repaired or replaced. As designed, pushbutton switches on a flat
panel are intended to be operated by a fingertip and, preferably,
give a tactile feedback to the user. Unfortunately, careless and
impatient users cause most flat switch panel failures. Gas pump
pushbutton switches, for example, are frequently operated by the
tip of a gas nozzle that is struck against the flat switch panel
for the purpose of actuating a particular switch. It is desirable
to have a sealed switch for devices that are exposed to the
elements and to harmful contaminants. A magnetically-coupled
pushbutton switch is one type of flat panel switch that may be
sealed and offers good tactile feedback to a user, but a
magnetically-coupled pushbutton switch includes a sheet metal
armature that is relatively thin compared to a gas nozzle.
[0002] Magnetically-coupled switches have a metal armature that is
normally held spaced from switch contacts by a sheet magnet. A
user-provided actuating force applied to the armature causes it to
snap free of the sheet magnet and close the switch contacts by
electrically connecting them. Release of the actuating force allows
the magnet to attract the armature back to a normal position, in
coupled engagement with the magnet so the armature is spaced from
the switch contacts, to reopen the switch. A magnetically-coupled
switch typically has the switch contacts formed on a non-conductive
substrate. A non-conductive spacer layer is fixed to the substrate,
with an opening in the spacer layer exposing the switch contacts.
The sheet magnet overlies the spacer layer. The armature is
magnetically-coupled to the bottom of the sheet magnet so that the
armature is housed within the opening in the spacer layer.
Preferably, the armature has a crown that protrudes through an
aperture in the magnet layer. Most often, a polyester membrane
layer with suitable graphics overlies the magnet layer to direct a
user of the switch as to location and function of the switch. The
benefits of magnetically-coupled pushbutton switches have been
demonstrated in U.S. Pat. Nos. 5,523,730, 5,666,096, 5,990,772 and
6,069,552, incorporated herein by reference.
SUMMARY OF THE INVENTION
[0003] The present invention concerns an impact spacer that
protects a pushbutton armature from being damaged during high
impact actuation. The impact spacer is installed under a switch
overlay, the overlay usually being a thin polyester sheet that has
graphics printed thereon to show a user where various switches are
located on a flat switch panel. The impact spacer is preferably a
thick sheet of polycarbonate plastic adhesively fixed to a thick
sheet of silicone rubber. When a high impact force is directed at a
flat switch panel, the crown of an armature is susceptible to being
crushed. The impact spacer protects the armature and crown by
spreading the energy of a high impact force throughout a large
volume of the impact spacer materials. The polycarbonate plastic
layer is rigid, so it spreads a localized impact laterally across a
large area of the flat switch panel. The underlying sheet of
silicone rubber dissipates the energy that has been spread out over
a large area of the impact spacer by deforming and compressing to
absorb the excess force delivered to the flat switch panel. Under a
normal actuation force, there is very little deformation of the
silicone rubber layer so that the tactile feedback delivered by the
armature is crisply transferred to a user.
[0004] Preferably, the polycarbonate plastic layer of the impact
spacer has an embossed area above each pushbutton switch. The
embossed area prevents excessive preloading of switches so that
thicker impact spacers may be used. Additional features of the
switch of the present invention include a pip on the crown of an
armature to preserve good tactile feedback, and a backer that is
fixed to the bottom of the flat switch panel to protect a circuit
layer of the switch against bending and cracking. Electrical leads
connect the circuit layer of the switch to electronics that are
external to the switch. Electrical conductors on the circuit layer
are arranged within the switch so that the pushbutton armature of
the switch is movable into and out of shorting relationship with
the electrical conductors to change the circuit logic for a circuit
incorporating the switch. As used herein, the term "top" refers to
that surface of any part in a cross sectional figure of the
drawings that faces the top edge of the page, while "bottom" refers
to that surface of any part in a cross sectional figure of the
drawings that faces the bottom edge of the page.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a cross-section of an impact absorbing system
according to the present invention incorporated for use with a
magnetically-coupled pushbutton switch.
[0006] FIG. 2 is a cross-section similar to FIG. 1, but with a
second type of impact spacer.
[0007] FIG. 3 is an exploded perspective view of the switch and
impact absorbing system of FIG. 1.
[0008] FIG. 4 is an exploded perspective view of the impact spacer
of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0009] As shown in FIGS. 1 through 4, the impact absorbing system
of the present invention always includes an impact spacer 2 that
has a rigid layer 4 and an energy-absorbing layer 6, but there are
several additional features shown and described in the foregoing
description that, though preferred, are not necessary and may be
excluded from the impact absorbing system where cost or preference
dictates otherwise. FIGS. 1 and 3 show the ideal impact absorbing
system as it would appear on a magnetically-coupled pushbutton
switch 8, or other flat panel switch that would benefit from the
impact absorbing system of the present invention. An impact
absorbing system that is capable of providing good tactile feedback
and a very high level of protection for a flat switch panel will
preferably include the following features: an embossed area 10 on
the rigid layer 4; a selective adhesive layer, not shown, between
the impact spacer 2 and the magnetically-coupled pushbutton switch
8; a reinforcement backer 12; and a pip 14 on the switch armature
16. Preferred materials and methods of attachment will be
discussed, but these preferences are not intended to exclude other
suitable or functionally equivalent materials or methods of
attachment.
[0010] FIG. 1 shows a magnetically-coupled pushbutton switch 8,
similar to the ones shown and described in the aforementioned U.S.
Patents, that has been modified to incorporate the impact absorbing
system of the present invention. A magnetically-coupled pushbutton
switch 8 typically includes, from the top down, a magnet coupler
layer 22, an aperture 24 through the magnet coupler layer, a metal
armature 16 having a crown 26 that protrudes through the aperture,
a spacer layer 28 that defines a switch cavity 30, and a substrate
32 that has electrical conductors formed thereon. The impact spacer
2 of the present invention is fixed to the top of the magnet
coupler layer 22 such that the energy-absorbing layer 6 is on or
adjacent the crown 26 of the armature 16. A thin polyester overlay
18 covers the impact spacer 2.
[0011] As already mentioned, the impact absorbing system of the
present invention always includes an impact spacer. The impact
spacer 2 is preferably made from two different sheets of material
that are adhesively bonded to each other by an elastomeric
adhesive. General adhesive, such as acrylic adhesive, will suffice,
but the elastomeric adhesive is preferred because of its superior
ability to permanently bond the layers of the impact spacer
together. The top sheet of the impact spacer 2 is the rigid layer
4, while the bottom sheet of the impact spacer is the
energy-absorbing layer 6. During an impact, the rigid layer 4
spreads a localized impact over a larger area of the
energy-absorbing layer 6. The energy-absorbing layer 6 compresses
and changes shape to disperse the energy of the impact throughout a
large volume of the energy-absorbing layer material. Some of the
force from the localized impact is transferred through the
energy-absorbing layer 6 to depress the pushbutton armature 16 and
actuate the switch, but the armature is protected from being
crushed or bent because of the impact spacer 2.
[0012] The rigid layer 4 of the impact spacer 2 is preferably a
sheet of polycarbonate material, such as Lexan.RTM., having a
thickness of between ten and thirty thousandths of an inch. Other
materials that could be used as the rigid layer include polyester,
nylon, vinyl, carbon fiber materials, or other similar materials
that offer some flexibility, but are substantially impervious to
compression and fracturing. The thickness of the rigid layer is
often dependent upon the material selected for use as the rigid
layer. There must be enough flexibility in the rigid layer so that
finger pressure will cause the rigid layer to adequately flex
during switch actuation. The finger pressure, or user provided
actuation force, is typically in the range of five to fifteen
ounces, but for some applications is fifty ounces or higher. If the
desired material to be used as the rigid layer 4 is well suited for
use as the overlay 18, appropriate graphics may be printed on the
rigid layer 4 so that the rigid layer takes the place of the
overlay that normally covers and protects a flat switch panel. If
there is concern that the graphics will wear off, the rigid layer
may be transparent with the graphics printed on the bottom surface
of the rigid layer. FIGS. 1 through 4 show a separate overlay 18
that would typically be adhesively fix to the top of the rigid
layer 4.
[0013] Where the rigid layer covers pushbuttons on a flat switch
panel that are in close proximity to each other, it may be
necessary to isolate actuation forces so that a user provided
actuation force applied to one pushbutton switch does not spread
out over the rigid layer and cause a nearby pushbutton switch to
also be actuated. Additionally, the stiffness of some rigid layer
materials may cause the armature 16 to be excessively preloaded so
that the switch does not fully return to an un-actuated position,
or the stiffness may negatively affect the tactile feedback of a
pushbutton switch making it difficult for a user to recognize
whether an actuation force was adequate. An isolation structure
that prevents accidental actuation of a pushbutton adjacent the
pushbutton intended to receive a user provided actuation force is
recommended. The preferred isolation structure is an embossed area
on the rigid layer that is around each area that will be above a
switch. FIGS. 1 and 3 show an embossed area 10 in the rigid layer
4. Note that the embossing causes the area of the rigid layer 4
above each switch to bulge away from the switch. For most purposes,
the size of each embossed area 10 is approximately the size of an
average fingertip, or roughly one third of a square inch. The
embossed area 10 improves flexibility of the rigid layer 4 just
above the pushbutton, but the increase flexibility does not
significantly affect the ability of the rigid layer to disperse the
energy of a high impact force over a large area of the rigid
layer.
[0014] FIGS. 2 and 4 show a second type of isolation structure that
utilizes a supplemental rigid layer 5 that is adhesively fixed to
the bottom of the rigid layer 4. Preferably, the rigid layer 4 in
FIGS. 2 and 4 is polyester and the supplemental rigid layer 5 is
polycarbonate, but the layers may be any of the materials
previously listed for use as the rigid layer. The supplemental
rigid layer 5 has cutouts 11 that align with an area above each
pushbutton, that area being about the size of a fingertip. As can
be seen in FIG. 4, the cutouts 11 in the supplemental rigid layer 5
may include passages that allow for pressure changes within the
cutouts to be vented, thereby keeping the tactile feedback more
uniform. The supplemental rigid layer 5 additionally spaces the
rigid layer 4 from each switch armature 16 so that preloading is
better controlled. The rigid layer 4 of FIGS. 2 and 4 is typically
thinner than the embossed rigid layer of FIGS. 1 and 3 because the
thickness of the supplemental rigid layer 5 contributes to the
ability of the impact spacer to spread the energy of a high impact
actuation over a large area of the energy-absorbing layer 6. The
supplemental rigid layer 5 does not cover a pushbutton, making it
easier for a user to actuate the switch because less force is
required to flex just the rigid layer 4. The main benefit of using
an isolation structure is to allow the impact spacer to be thicker
than would otherwise be possible. Without an isolation structure,
the thickness of the rigid layer 4 is significantly limited because
of problems with excessive preloading and loss of tactile
feedback.
[0015] In FIGS. 1 through 4, the energy-absorbing layer 6 of the
impact spacer 2 is preferably a sheet of silicone rubber material
having a thickness of between thirty and eighty thousandths of an
inch. There are, of course, numerous other materials that mimic the
energy-absorbing property of silicone rubber such as, but not
limited to, other rubber materials, gelatins and foams. The
energy-absorbing layer 6 dissipates a lot of the energy of a high
impact actuation force by deforming and compressing a large volume
of the energy-absorbing layer material. The energy-absorbing layer
6 is usually in direct contact with the crown 26 of each pushbutton
switch that is part of the flat switch panel. This direct contact
causes mild preloading of each switch. Preloading normally does not
result in a bulge on the top surface of the rigid layer 4 because
the energy-absorbing layer 6 slightly compresses and deforms around
the crown 26. Under a normal actuation force, the energy-absorbing
layer 6 is compressed above the crown 26 of a pushbutton until a
breakaway force is achieved. The breakaway force causes the
pushbutton to move into contact with electrical conductors of the
switch. The compressed portion of the energy-absorbing layer
material travels with the crown 26 during switch travel. There is a
tactile feedback to the user when the pushbutton abruptly meets the
substrate 32 of the switch. That tactile feedback is crisply
transferred through the compressed portion of the energy-absorbing
layer 6 to the rigid layer 4 and overlay 18.
[0016] An additional feature of the impact spacer 2 that is
recommended is to use a selective adhesive layer, not shown, to fix
the pushbutton switch 8 to the bottom of the energy-absorbing layer
6. Adhesive layers are usually about five thousandths of an inch
thick. By selective, it is meant that there are areas on the
energy-absorbing layer 6 that do not receive adhesive. These areas
that do not receive adhesive are above each pushbutton switch. If
adhesive were left above each pushbutton switch, the
energy-absorbing layer 6 could bind during actuation and prevent
the switch from returning normally to an un-actuated position.
Another benefit of the selective adhesive layer is that the
energy-absorbing layer 6 has more freedom of movement so that it
can deform more than would be possible if it were adhered to the
pushbutton. Where the energy-absorbing layer 6 is silicone rubber,
a silicone adhesive, such as elastomeric adhesive made by 3-M
corporation, should be used so that the impact spacer 2 is
permanently fixed to the switch panel.
[0017] Depending on the material of the substrate 32, there may be
a need for additional support under the substrate 32. If the
substrate 32 is likely to flex so much during high impact actuation
that the armature 16 may bend, or the substrate is likely to
fracture, then a backer 12 should be attached to the bottom of the
substrate. The backer 12 is a layer of material that provides
additional support to the substrate 32 and is also capable of
absorbing excess energy from a high impact actuation force. The
backer 12 is preferably polycarbonate, but could also be sheet
metal, wood, cork, or any of the rigid layer materials previously
mentioned.
[0018] For ultra high impact actuation forces, the thickness of the
impact spacer should be increased. However, making a thicker impact
spacer usually is at the cost of tactile feedback to the user. If
it is necessary to use an impact spacer 2 that is very thick, the
armature crown 26 should include a pip 14. The pip 14 is a small
raised area on the top of the crown 26. The pip 14 is an extension
of the crown 26 that allows the crown to extend farther into the
energy-absorbing layer 6 so that tactile feedback can be focused
and transferred through the pip 14 to the user. The pip 14 brings
the top of the armature crown 26 closer to the user so that the
required actuation force is lower than it would be without the pip.
Because the pip 14 has very little surface area, it can poke into
the energy absorbing material without contributing very much to
preloading. Although the relatively small area of the pip reduces
the magnitude of force directed toward the armature crown, focusing
the actuation force onto the pip enhances the tactile feedback to a
user.
[0019] While a preferred form of the invention has been shown and
described, it will be realized that alterations and modifications
may be made thereto without departing from the scope of the
following claims. For example, the impact spacer 2 could be made
from a single material, such as a thermoplastic elastomer, that can
function as both the rigid layer 4 and the energy-absorbing layer
6, but the materials cost of such an alternative was not
competitive at the time of invention.
* * * * *