ASTM F2592-10
(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
SIGNIFICANCE AND USE
The force and displacement values when converted to a slope are useful in quantifying the differences in tactile response among membrane switches.
Specified resistance is useful to manufacturers and users when designing membrane switch interface circuitry.
Actuation force and contact force are useful to manufacturers and users in determining the suitability, reference and aesthetics of a membrane switch in a given application.
The tendency of a switch to make or break electrical contact at unexpected moments during closure or release can be a sign of a poor design. The degree of teasing can range from a simple annoyance to a failure of critical control process.
The amount of switch sensitivity or teasing can also be a result of poor surface conductivity that will prevent an electrical event even when switch poles are in partial contact.
SCOPE
1.1 This test method covers the measurement of force displacement characteristics of a membrane switch.
1.1.1 This test method replaces Test Method F1570 (Tactile Ratio). Tactile Actuating Slope Angle and Tactile Recovery Slope Angle better represent the characterization of tactile sensation, previously called “Tactile Ratio” in Test Method F1570.
1.1.2 This test method replaces Test Method F1682 (Travel).
1.1.3 This test method replaces Test Method F1597 (Actuation and Contact Force).
1.1.4 This test method replaces Test Method F1997 (Switch Sensitivity).
1.2 Force displacement hysterisis loop curve can be used in the determination of Actuation Force, Displacement, Contact Force, Return Force, and Tactile Actuating Slope Angle and Tactile Recovery Slope Angle.
1.3 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 − 10
StandardTest Method for
1
Measuring the Force-Displacement of a Membrane Switch
This standard is issued under the fixed designation F2592; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.6 contact displacement (Tc)—the displacement at con-
tact closure.
1.1 This test method covers the measurement of force
displacement characteristics of a membrane switch. 2.1.7 contact force (Fc)—the force at contact closure.
1.1.1 This test method replaces Test Method F1570 (Tactile
2.1.8 displacement—measured distance of movement when
Ratio). Tactile Actuating Slope Angle and Tactile Recovery
membrane is depressed.
Slope Angle better represent the characterization of tactile
2.1.8.1 Discussion—Displacement is sometimes referred to
sensation, previously called “Tactile Ratio” in Test Method
as “switch travel.”
F1570.
2.1.9 Fmax—an applied force, maximum force measured
1.1.2 This test method replaces Test Method F1682
prior to or including point (Fmin) (see Fig. 1).
(Travel).
2.1.9.1 Discussion—Sometimes referred to as Actuation
1.1.3 This test method replaces Test Method F1597 (Actua-
Force.
tion and Contact Force).
1.1.4 This test method replaces Test Method F1997 (Switch 2.1.10 Fmin—an applied force, minimum force seen be-
Sensitivity).
tween Fmax and point at which probe movement ceases.
2.1.10.1 Discussion—Fmax can equal Fmin.
1.2 Force displacement hysterisis loop curve can be used in
the determination of Actuation Force, Displacement, Contact
2.1.11 force-displacement hysteresis curve—relationship
Force, Return Force, and Tactile Actuating Slope Angle and
between force applied and displacement of a membrane switch
Tactile Recovery Slope Angle.
in terms of the actuation and return (recovery).
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
responsibility of the user of this standard to establish appro-
2.1.12 force factor – make (Ffactor)—mathematical expres-
priate safety and health practices and determine the applica-
sion for the change in force between Fmax and Fmin (see Eq
bility of regulatory limitations prior to use.
7.1.1).
2.1.12.1 Discussion—Ffactor = 0 for non-tactile switch.
2. Terminology
2.1.13 force factor – break (Frfactor)—mathematical ex-
2.1 Definitions:
pression for the change in force between Frmax and Frmin
2.1.1 break displacement (Tb)—the displacement at contact
(see Eq 7.1.2).
break.
2.1.13.1 Discussion—Frfactor = 0 for non-tactile switch.
2.1.2 break force (Fb)—the force at contact break.
2.1.14 membrane switch—a momentary switching device in
2.1.3 circuit resistance—electrical resistance as measured
which at least one contact is on, or made of, a flexible
between two test points whose internal contacts, when held
substrate.
closed, complete a circuit.
2.1.15 non-tactile switch—switch that does not have a
2.1.4 closure (make)—the event at which a specified resis-
tactile response and therefore has a response slope equal to
tance is achieved.
zero because Fmax and Fmin are the same (see Fig. 2).
2.1.5 contact break—point at which circuit resistance is
2.1.16 return min force (Frmin)—minimum force seen dur-
higher than specified resistance on return.
ing return cycle before reaching Frmax.
2.1.17 return max force (Frmax)—maximum force mea-
1
This test method is under the jurisdiction of ASTM Committee F01 on
sured during return cycle after achieving Frmin.
Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane
Switches.
2.1.18 specified resistance—maximum allowable resistance
Current edition approved Dec. 1, 2010. Published January 2011. Originally
as measured between two terminations whose internal switch
approved in 2006. Last previous edition approved in 2009 as F2592-09. DOI:
10.1520/F2592-10. contacts are held closed to complete a circuit.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F2592 − 10
NOTE 1—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
2.1.19 switch teasing (break)—the displacement measure- 2.1.29 travel factor – make (Tfactor)—mathematical ex-
ment on the force-displacement curve between contact break pression for the change in displacement between Tfmax and
(Fb) and return force (Fr
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F2592–09 Designation:F2592–10
Standard Test Method for
1
Measuring the Force-Displacement of a Membrane Switch
This standard is issued under the fixed designation F2592; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the measurement of force displacement characteristics of a membrane switch.
1.1.1 This test method replaces Test Method F1570 (Tactile Ratio). Tactile ResponseActuating Slope Angle and Tactile
Recovery SlopeAngle better represents the characterization of tactile sensation, previously called “Tactile Ratio” in Test Method
. F1570.
1.1.2 This test method replaces Test Method F1682 (Travel).
1.1.3 This test method replaces Test Method F1597 (Actuation and Contact Force).
1.1.4 This test method replaces Test Method F1997 (Switch Sensitivity).
1.2 ForcedisplacementhysterisisloopcurvecanbeusedinthedeterminationofActuationForce,Displacement,ContactForce,
Return Force, and Tactile Response Slope. Actuating Slope Angle and Tactile Recovery Slope Angle.
1.3 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.
2. Terminology
2.1 Definitions:
2.1.1 break displacement (Tb)—the displacement at contact break.
2.1.2 break force (Fb)—the force at contact break.
2.1.3 circuit resistance—electrical resistance as measured between two test points whose internal contacts, when held closed,
complete a circuit.
2.1.4 closure (make)—the event at which a specified resistance is achieved.
2.1.5 contact break—point at which circuit resistance is higher than specified resistance on return.
2.1.6 contact displacement (Tc)—the displacement at contact closure.
2.1.7 contact force (Fc)—the force at contact closure.
2.1.8 displacement—measured distance of movement when membrane is depressed.
2.1.8.1 Discussion—Displacement is sometimes referred to as “switch travel.”
2.1.9 Fmax—an applied force, maximum force measured prior to or including point (Fmin) (see Fig. 1).
2.1.9.1 Discussion—Sometimes referred to as Actuation Force.
2.1.10 Fmin—an applied force, minimum force seen between Fmax and point at which probe movement ceases.
2.1.10.1 Discussion—Fmax can equal Fmin.
2.1.11 force-displacement hysteresis curve—relationship between force applied and displacement of a membrane switch in
terms of the actuation and return (recovery).
2.1.11.1 Discussion—Usually expressed as a line graph; sometimes referred to as Force-Travel curve (see Fig. 1).
2.1.12 force factor – make (Ffactor)—mathematicalexpressionforthechangeinforcebetween Fmaxand Fmin(seeEq7.1.1).
2.1.12.1 Discussion—Ffactor = 0 for non-tactile switch.
2.1.13 force factor – break (Frfactor)—mathematical expression for the change in force between Frmax and Frmin (see Eq
7.1.2).
2.1.13.1 Discussion—Frfactor = 0 for non-tactile switch.
2.1.14 membrane switch—a momentary switching device in which at least one contact is on, or made of, a flexible substrate.
2.1.13
1
This test method is under the jurisdiction of ASTM Committee F01 on Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane Switches.
Current edition approved June 15, 2009. Published July 2009. Originally approved in 2006. Last previous edition approved in 2008 as F2592-08. DOI: 10.1520/F2592-09.
Current edition approved Dec. 1, 2010. Published January 2011. Originally approved in 2006. Last previous edition approved in 2009 as F2592-09. DOI:
10.1520/F2592-10.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
F2592–10
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
2.1.15 non-tactile switch—switch that does not have a tactile response and therefore has a response slope equal to zero because
Fmax and Fmin are the same (see Fig. 2).
2.1.14
2.1.16 return min force (Frmin)—minimum force seen during return cycle before reaching Frmax.
2.1.15
2.1.17 return max force (Frmax)—maximum force measured d
...
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