ASTM F2592-07
(Test Method)Standard Test Method for Measuring the Force-Displacement of a Membrane Switch
Standard Test Method for Measuring the Force-Displacement of a Membrane Switch
SCOPE
1.1 This test method covers the measurement of force displacement characteristics of a membrane switch.
1.2 Hysteresis (force-displacement) curve can be used in the determination of Actuation Force, Displacement, Contact Force, Restoration Force, and Tactile Response Slope.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:F2592–07
Standard Test Method for
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Measuring the Force-Displacement of a Membrane Switch
This standard is issued under the fixed designation F 2592; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.10 Fmin—an applied force, minimum force seen be-
tween Fmax and point at which probe movement ceases.
1.1 This test method covers the measurement of force
2.1.10.1 Discussion—Fmax can equal Fmin.
displacement characteristics of a membrane switch.
2.1.11 force-displacement hysteresis curve—relationship
1.2 Hysteresis (force–displacement) curve can be used in
between force applied and displacement of a membrane switch
the determination of Actuation Force, Displacement, Contact
in terms of the actuation and return (recovery).
Force, Restoration Force, and Tactile Response Slope.
2.1.11.1 Discussion—Usually expressed as a line graph;
1.3 This standard does not purport to address all of the
sometimes referred to as Force-Travel curve (see Fig. 1).
safety concerns, if any, associated with its use. It is the
2.1.12 membrane switch—a momentary switching device in
responsibility of the user of this standard to establish appro-
which at least one contact is on, or made of, a flexible
priate safety and health practices and determine the applica-
substrate.
bility of regulatory limitations prior to use.
2.1.13 non-tactile switch—switch that does not have a
2. Terminology
tactile response and therefore has a response slope equal to
zero because Fmax and Fmin are the same (see Fig. 2).
2.1 Definitions:
2.1.14 recovery slope—rate of change of return force with
2.1.1 break displacement (Tb)—the displacement at contact
respect to displacement, as measured between TFmin and
break.
TFrmax (see Fig. 2 and Fig. 3).
2.1.2 break force (Fb)—the force at contact break.
2.1.15 return min force (Frmin)—minimum force seen
2.1.3 circuit resistance—electrical resistance as measured
during return cycle before reaching Frmax.
between two test points whose internal contacts, when held
2.1.16 return max force (Frmax)—maximum force mea-
closed, complete a circuit.
sured during return cycle after achieving Frmin.
2.1.4 closure (make)—the event at which a specified resis-
2.1.17 specified resistance—maximum allowable resistance
tance is achieved.
as measured between two terminations whose internal switch
2.1.5 contact break—point at which circuit resistance is
contacts are held closed to complete a circuit.
higher than specified resistance on return.
2.1.18 switch teasing (break)—the displacement measure-
2.1.6 contact displacement (Tc)—the displacement at con-
ment on the force-displacement curve between contact break
tact closure.
(Fb) and return force (Frmin).
2.1.7 contact force (Fc)—the force at contact closure.
2.1.19 switch teasing (make)—the displacement measure-
2.1.8 displacement—measured distance of movement when
ment on the force-displacement curve between contact force
a membrane switch is depressed.
(Fc) and minimum force (Fmin).
2.1.9 Fmax—an applied force, maximum force measured
2.1.20 tactile response—a physical sensation, caused by a
prior to or including point (Fmin) (see Fig. 1).
sudden collapse or snapback, or both, of a membrane switch.
2.1.9.1 Discussion—Sometimes referred to as Actuation
2.1.21 tactile response slope (TRS)—rate of change of
Force.
applied force with respect to displacement, as measured
between Tfmax and Tfmin (see Figs. 3 and 4).
2.1.22 tactile switch—a switch that has a tactile response
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This test method is under the jurisdiction of ASTM Committee F01 on
and therefore has a response slope less than zero (negative
Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane
slope).
Switches.
2.1.23 Tb—displacement at contact break.
Current edition approved Feb. 1, 2007. Published March 2007. Originally
approved in 2006. Last previous edition approved in 2006 as F 2592-06. 2.1.24 Tfmax—Displacement at Fmax.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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F2592–07
NOTE—Area between forward and return curves is the difference in work by the tactile mechanism showing hysterisis in the tactile system.
FIG. 1 Force Displacement Hysterisis Loop
2.1.25 Tfmin—Displacement at Fmin. 4. Interferences
2.1.26 Tfrmax—displacement at Frmax.
4.1 Results compared between a manual system and auto-
2.1.27 Tfrmin—displacement at Frmin.
mated system can be significant based on the response time of
operator and the equipment.
3. Significance and Use
4.2 Thesw
...
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