Information
-
Patent Grant
-
6331928
-
Patent Number
6,331,928
-
Date Filed
Thursday, May 27, 199924 years ago
-
Date Issued
Tuesday, December 18, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Duft, Graziano & Forest
- Bailey; Wayne P.
-
CPC
-
US Classifications
Field of Search
US
- 174 32
- 174 35 R
- 174 35 GC
- 174 35 MS
- 174 256
- 200 305
- 200 512
- 361 212
- 361 220
- 361 816
-
International Classifications
-
Abstract
The invention provides an ESD-protected interface panel. A signal board has one or more circuit layers and at least one button switch on a first side of the board. An electrical output (e.g., an electrical cable and/or connector) connects in circuit with the board and switch, and the signal board generates signals on the electrical output indicative of activation of the button switch. An ESD protection layer covers the button switch and substantially all of the first side. The ESD layer is deformable to human touch to activate the switch therethrough. The ESD layer electrically couples with one or more contacts covering at least part of the second side, such that ESD generated by the human touch is routed to chassis ground connected to the contacts. Preferably, the ESD layer bends around edges of the signal board to form the contacts in a single conductive layer. An indication layer, e.g., formed of polycarbonate material, preferably covers the ESD layer over the first side with embossed graphics over the button switch. The indication layer is deformable to human touch whereby pressing the embossed graphics deforms the indication layer, and thus the ESD protection layer, and activates the button switch therebelow. An adhesive (e.g., a double sided adhesive layer, or glue) covers at least part of the second side of the signal board, except for the contacts, so that the panel is easily bonded to electrical equipment, with the contacts coupling to chassis ground. The invention provides enhanced ESD protection even with various electrical components electrically coupled with the signal board, such as LEDs and other button switches, and further permits windowing through the panel to view directly the underlying electrical equipment.
Description
FIELD OF THE INVENTION
The invention relates to protection against electrostatic discharge caused by human touch with an interface panel.
BACKGROUND OF THE INVENTION
Electrostatic discharge (“ESD”) is known to cause damage to electrical components and equipment. The prior art has developed certain ways to protect electrical equipment from human touch through specially designed user keypad panels.
FIGS. 1 and 1A
illustrate one such user keypad panel
10
. Specifically,
FIG. 1
shows a top view of keypad panel
10
; and
FIG. 1A
shows a cross-sectional view of keypad panel
10
. The upper-most layer of panel
10
is an embossed polycarbonate or polyester layer
11
, which, for purpose of illustration, is shown transparent so as to view ESD screen layer
12
. ESD screen layer
12
includes a silver-painted cross-hatch conductive pattern
12
a
that is connected to a conductive ESD tail
14
. ESD tail
14
forms a mounting hole
16
used to electrically connect pattern
12
a
to equipment chassis.
FIG. 1A
shows further detail of keypad panel
10
, including button switch
18
, button spacer layer
20
, signal trace layer
22
, and adhesive layer
23
. Layer
11
includes an embossed button pattern
11
a
-illustratively shown as a dotted line in FIG.
1
and as an upward protrusion in FIG.
1
A. Button pattern
11
a
is adjacent button switch
18
so that human pressure on embossed button pattern
11
a
activates button switch
18
through deformation of ESD screen layer
12
. Button switch
18
is known in the art and operates with signal trace layer
22
to generate signals—via switch circuitry
22
a
—indicative of switch activation. These signals are detected in signal layer
22
by known techniques such as through signal cable
24
. Spacer layer
20
is used to form a space between ESD layer
12
and signal trace layer
22
. Adhesive layer
23
bonds panel
10
to a flat surface associated with electrical equipment.
Although keypad panel
10
is shown with only one button
11
a
, other buttons can be included. By way of example, button
11
a
can be a power on and power off button to the electrical equipment.
In operation, a user operates the electrical equipment through keypad panel
10
. Screen layer
12
a
arguably attracts ESD pulses which are in turn shunted, through ESD tail
14
, to chassis ground associated with the electrical equipment. ESD tail
14
is mounted to chassis ground with a screw and nut through mounting hole
16
.
One problem with prior art panel
10
is that differential voltages can exist between lines of the cross-hatch pattern
12
a
, leaving residual voltage potential energy resident in ESD layer
12
even though other energy is drained off through ESD tail
14
. Another problem is that panel
10
requires additional manufacturing cost and time due to ESD tail
14
, and due to the nut and screw required to attach ESD tail
14
to chassis ground. Yet another problem is that ESD pulses are routed through a single location associated with panel
10
, i.e., at ESD tail
14
.
One object of the invention is to provide a new and improved ESD keypad panel that reduces or eliminates the above-described problems.
Another object of the invention is to provide an ESD protection panel with multiple ESD shunt contacts to improve grounding to equipment chassis.
Yet another object of the invention is to provide an ESD protection panel that has improved ESD protection capability, as compared to the prior art, and which requires less cost and manufacturing time.
Still another object of the invention is to provide an ESD-protected keyboard panel which has increased protection against ESD pulses coupling to associated electrical equipment.
These and other objects will become apparent in the description that follows.
SUMMARY OF THE INVENTION
In one aspect, the invention provides an ESD-protected interface panel. A signal board has one or more circuit layers and at least one button switch on a first side of the board. An electrical output connects in circuit with the board and switch, and the signal board generates signals on the electrical output indicative of activation of the button switch. An ESD protection layer covers the button switch and substantially all of the first side. The ESD layer is deformable to human touch to activate the switch therethrough. The ESD layer bends around at least one edge of the board to form one or more contacts covering at least part of the second side, such that ESD generated by the human touch is routed to chassis ground electrically connected to the contacts.
The invention also provides a method for protecting electrical equipment from ESD pulses generated by users at an interface panel, the interface panel of the type which includes a signal board with at least one button on a first side of the signal board for generating signals through the signal board in response to activation of the button switch, including the steps of: covering the button switch with an ESD layer that is deformable to human touch to activate the switch therethrough; and bending the ESD layer around at least one edge of the signal board to form one or more contacts covering at least part of a second side of the ESD board, wherein ESD generated by the human touch is routed to chassis ground connected to the contacts.
The invention is next described further in connection with preferred embodiments, and it will become apparent that various additions, subtractions, and modifications can be made by those skilled in the art without departing from the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the invention may be obtained by reference to the drawings, in which:
FIGS. 1 and 1A
schematically illustrate a prior art ESD keypad panel;
FIG. 2
schematically illustrates a front view of an ESD protection panel constructed according to the invention;
FIG. 2A
shows a back view of the ESD protection panel of
FIG. 2
;
FIG. 2B
shows a cross-sectional view of the panel of
FIG. 2 through a
button switch to illustrate the invention in comparison to the prior art embodiment of
FIG. 1A
;
FIG. 2C
shows a cross-sectional view of the panel of FIG.
2
through an LED; and
FIG. 2D
shows a cross-sectional view of the panel of
FIG. 2 through a
window permitting viewing through the panel to underlying electrical equipment.
FIG. 3
shows a cross-sectional view of the panel of
FIG. 2
with the ESD layer and indication layer each forming an aperature over the button switch such that a user can directly access the button switch through the indication layer.
DETAILED DESCRIPTION OF THE DRAWINGS
The invention provides an ESD-protected interface panel. A signal board has one or more circuit layers and at least one button switch on a first side of the board. An electrical output connects in circuit with the board and switch, and the signal board generates signals on the electrical output indicative of activation of the button switch. An ESD protection layer covers the button switch and substantially all of the first side. The ESD layer is deformable to human touch to activate the switch therethrough. The ESD layer bends around at least one edge of the board to form one or more contacts covering at least part of the second side, such that ESD generated by the human touch is routed to chassis ground electrically connected to the contacts. As an alternative, one or more of the contacts are separate from the ESD layer but electrically coupled thereto, providing an electrically integrated ESD layer with the contacts shunting ESD pulses to chassis ground, as above. In one aspect, the output includes an electrical cable. The output can also include an electrical connector.
In a preferred aspect, an indication layer covers the ESD layer over the first side. The indication layer has graphics indicative of the switch disposed below the indication layer and the ESD protection layer. The indication layer is deformable to human touch whereby pressing the graphics deforms the indication layer, and thus the ESD protection layer, and thus activates the button switch. The indication layer of one aspect is a polycarbonate layer. The indication layer of another aspect has embossing that forms the graphics. The indication layer of yet another aspect includes a polyester layer.
In another aspect, an indication layer covers the ESD layer over the first side, and the ESD layer and indication layer jointly form an aperture over the button switch such that a user can directly access the button switch through the indication layer. The button switch is formed of material such as rubber, silicon elastomer and/or silicon rubber.
The signal board of one aspect includes a LED on the first side connected in circuit with the signal board, such that the ESD protection layer forms an aperture over the LED so that the LED is seen. In one aspect, an indication layer covers at least part of the ESD layer over the first side. The indication layer forms a window adjacent the aperture such that a user can see the LED operating through the ESD layer.
In another aspect, an adhesive layer covers at least part of the second side without covering the contacts. Preferably, the adhesive layer has a first thickness and the ESD protection layer has a second thickness that is greater than the first thickness, such that placement of the panel on a flat surface ensures electrical connection between the contacts and the chassis ground associated with the flat surface. By way of example, the adhesive layer can have a thickness of approximately 0.002 inch and the ESD protection layer can have a thickness of approximately 0.003 inch. Preferably, the panel provides ESD protection to at least 25,000 Volts.
In yet another aspect, the signal board forms a first aperture for viewing through the panel. The ESD protection layer forms a second aperture substantially coincident with the first aperture. An indication layer covers the ESD layer over the first side. The indication layer indicates where the switch is disposed below the indication layer and ESD protection layer. The indication layer has a clear window substantially coincident with the first and second apertures to permit viewing through the panel. Preferably, an adhesive layer covers at least part of the second side without covering the contacts and the first aperture.
A signal board of one aspect includes a button circuit layer and an LED circuit layer. The button circuit layer facilitates operation of the button switch; and the LED circuit layer facilitates operation of an LED connected with the signal board. In one related aspect, the circuit layer includes a separate tail connecting the signal board to external electronics. A cable can be used to connect each circuit layer to external electronics.
FIG. 2
schematically illustrates a front view of one ESD protection panel
50
of the invention. Panel
50
connects to electrical equipment
52
so that a user can interface with equipment
52
while protecting equipment
52
from ESD pulses. As illustrated, panel
50
has a window
53
permitting viewing of underlying instrumentation
54
(here shown as an electrical gauge) through panel
50
. Panel
50
also has an ON/OFF button
58
and an LED
60
indicating when equipment
52
is ON or OFF relative to operation of button
58
. The indication layer
62
of panel
50
is preferably a polycarbonate layer that is embossed to form graphics indicative of button
58
. Those skilled in the art should appreciate that other material can be used for layer
62
, including polyester; and also that button
58
can be formed by stenciled or ink graphics as alternatives to embossing. Indication layer
62
preferably has a window
55
arranged coincident with LED
60
so that LED light passes through layer
62
.
Panel
50
includes an electrical cable
64
and connector
66
used to obtain signals from panel
50
, and in particular from the signal board (not shown in
FIGS. 2 and 2A
) discussed below.
FIG. 2A
illustrates a back side
50
a
of panel
50
, including a plurality of electrical contacts
68
that integrally connect to the ESD layer (not shown in
FIGS. 2 and 2A
) discussed below. Electrical adhesive
70
bonds panel
50
to electrical equipment
52
,
FIG. 2
, such that contacts
68
are electrically coupled to chassis ground associated with equipment
52
. In this way, ESD pulses generated by human touch to button
58
, for example, are shunted to chassis ground through contacts
68
.
Those skilled in the art should appreciate that adhesive
70
can be applied accurately and geometrically to the back
50
a
of panel
50
, by known techniques. Adhesive
70
is preferably applied to back
50
a
without covering any part of contacts
68
to ensure good electrical connection between contacts
68
and chassis ground.
FIG. 2B
shows a cross-sectional view of panel
50
through button
58
. As shown, button
58
is formed into indication layer
62
of panel
50
by embossing. ESD layer
74
resides below layer
62
to shunt ESD pulses to contacts
68
. Button switch
76
and button spacer layer
78
reside below ESD layer
74
, as shown. Signal board
80
communicates electronic signals indicative of button switch operation as generated by switch circuitry
82
. Adhesive layer
70
bonds panel
50
to electrical equipment
52
.
ESD layer
74
thus forms a protective ESD shield between layer
62
and button switch
76
. When a user presses button
58
, ESD layer
74
deforms to activate button switch
76
; however ESD pulses are shunted to contacts
68
, coupled to chassis ground.
FIG. 2C
shows a cross-sectional view of panel
50
through LED
60
and window
55
. Window
55
is formed into indication layer
62
of panel
50
through known techniques. As above, ESD layer
74
below layer
62
shunts ESD pulses to contacts
68
. ESD layer
74
forms an aperture
74
a
through which LED
60
protrudes. Signal board
80
communicates electronic signals to facilitate operation of LED
60
by known techniques.
FIG. 2D
shows a cross-sectional view of panel
50
through window
53
and cable and connector
64
,
66
. Window
53
permits viewing of instrumentation
54
associated with equipment
52
, as shown. To form window
53
, ESD layer
74
forms a corresponding aperture
74
b
through ESD layer
74
to permit viewing therethrough. Further, signal board
80
and button layer
78
form similar apertures
80
b
,
78
b
, respectively, for the same purpose. Adhesive
70
also thus preferably forms an aperture
70
b.
FIG. 2D
also illustrates connection between cable
64
and connector
66
to signal board
80
through ESD aperture
74
d.
In an alternate embodiment, as shown in
FIG. 3
, indication layer
62
covers the ESD layer
74
over the first side, and the ESD layer
74
and indication layer
62
jointly form an aperture
84
over the button switch
76
such that a user can directly access the button switch
76
through the indication layer
62
.
The invention also provides a method for protecting electrical equipment from ESD pulses generated by users at an interface panel, the interface panel of the type which includes a signal board with at least one button on a first side of the signal board for generating signals through the signal board in response to activation of the button switch, including the steps of: covering the button switch with an ESD layer that is deformable to human touch to activate the switch therethrough; and bending the ESD layer around at least one edge of the signal board to form one or more contacts covering at least part of a second side of the ESD board, wherein ESD generated by the human touch is routed to chassis ground connected to the contacts.
In other aspects, the method includes the steps of (a) covering the first side of the ESD layer with an indication layer and (b) providing graphics in the indication layer indicative of the button switch disposed below the indication layer and the ESD protection layer, such that deformation of the indication layer graphics in response to human touch activates the button switch. The graphics are preferably embossed into the indication layer.
The method of one aspect includes the further steps of attaching the second side of the signal board to the electrical equipment via an adhesive layer covering part of the second side, without covering the contacts, and electrically coupling the contacts to the chassis ground.
The invention thus attains the objects set forth above, among those apparent from preceding description. Since certain changes may be made in the above systems and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing be interpreted as illustrative and not in a limiting sense.
In view of the foregoing, what is claimed is:
Claims
- 1. An ESD-protected interface panel, comprising:a signal board comprising a first and second side; and an ESD protection layer covering substantially all of the first side and extending around at least one edge of the signal board to form at least one contact covering at least part of the second side, wherein chassis ground is connected to the at least one contact, the ESD protection layer being deformable to human touch to activate an underlying switch coupled to the signal board.
- 2. The panel of claim 1, further comprising an indication layer covering at least a portion of the ESD protection layer over the first side, the indication layer having graphics indicative of a switch disposed below the indication layer and the ESD protection layer, the indication layer being deformable to human touch to activate the switch by pressing the indication layer and thus the switch.
- 3. The panel of claim 1, further comprising an indication layer covering at least a portion of the ESD protection layer over the first side, wherein the ESD protection layer and indication layer each form an aperture over a switch on the signal board such that a user can directly access the switch through the indication layer.
- 4. The panel of claim 1, wherein the signal board further comprises a LED on the first side of the signal board, wherein the ESD protection layer forms an aperture over the LED such that the LED is seen.
- 5. The panel of claim 4, further comprising an indication layer covering at least part of the ESD protection layer over the first side, the indication layer forming a window adjacent the aperture such that a user can see the LED operating through the ESD protection layer.
- 6. The panel of claim 1, further comprising an adhesive layer covering at least part of the second side.
- 7. The panel of claim 6, wherein the adhesive layer has a first thickness and wherein the ESD protection layer has a second thickness that is greater than the first thickness, wherein placement of the panel on a flat surface ensures electrical connection between the at least one contact and chassis ground associated with the flat surface.
- 8. The panel of claim 1, wherein the signal board forms a first aperture for viewing through the panel, the ESD protection layer forming a second aperture substantially coincident with the first aperture, and further comprising an indication layer substantially covering the ESD protection layer over the first side, the indication layer indicating a switch disposed below the indication layer and ESD protection layer, the indication layer having a clear window substantially coincident with the first and second apertures to permit viewing through the panel.
- 9. A method for protecting electrical equipment from ESD pulses generated by users at an interface panel, the interface panel of a type which includes a signal board with at least one switch on a first side of the signal board for generating signals through the signal board in response to activation of the switch, comprising the steps of:covering the switch with an ESD protection layer that is deformable to human touch to activate the switch therethrough; and bending the ESD protection layer around at least one edge of the signal board to form at least one contact covering at least part of a second side of the signal board, wherein ESD generated by the human touch is routed to chassis ground connected to the at least one contact.
- 10. The method of claim 9, further comprising the steps of covering the first side of the ESD protection layer with an indication layer, wherein deformation of the indication layer in response to human touch activates the switch.
- 11. The method of claim 9, further comprising the steps of attaching the second side of the signal board to the electrical equipment via an adhesive layer covering at least a portion of the second side and electrically coupling the at least one contact to the chassis ground.
US Referenced Citations (7)
Foreign Referenced Citations (4)
Number |
Date |
Country |
8527651 U |
Dec 1985 |
DE |
0 703 591 A |
Mar 1996 |
EP |
2 282 915 A |
Apr 1995 |
GB |
07307779 A |
Nov 1995 |
JP |