ESD-protected interface panel and associated methods

Details ESD-protected interface panel and associated methods ESD-protected interface panel and associated methods

1999-05-27

2001-12-18

Fleming, Fritz (Department: 2836)

Electricity: electrical systems and devices

Discharging or preventing accumulation of electric charge

C361S220000

Reexamination Certificate

active

06331928

ABSTRACT:

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.


REFERENCES:
patent: 4303960 (1981-12-01), Sherwood et al.
patent: 4375585 (1983-03-01), Lee
patent: 4786767 (1988-11-01), Kuhlman
patent: 4814566 (1989-03-01), Sigl
patent: 4894493 (1990-01-01), Smith et al.
patent: 5063474 (1991-11-01), Igarashi
patent: 5383097 (1995-01-01), DeLucia et al.
patent: 8527651 U (1985-12-01), None
patent: 0 703 591 A (1996-03-01), None
patent: 2 282 915 A (1995-04-01), None
patent: 07307779 A (1995-11-01), None

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