ASTM_F_2592_-_10.pdf

Designation:F259210Standard Test Method forMeasuring the Force-Displacement of a Membrane Switch1This standard is issued under the fixed designation F2592;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of forcedisplacement characteristics of a membrane switch.1.1.1 This test method replaces Test Method F1570(TactileRatio).Tactile Actuating Slope Angle and Tactile RecoverySlope Angle better represent the characterization of tactilesensation,previously called“Tactile Ratio”in Test MethodF1570.1.1.2 This test method replaces Test Method F1682(Travel).1.1.3 This test method replaces Test Method F1597(Actua-tion and Contact Force).1.1.4 This test method replaces Test Method F1997(SwitchSensitivity).1.2 Force displacement hysterisis loop curve can be used inthe determination of Actuation Force,Displacement,ContactForce,Return Force,and Tactile Actuating Slope Angle andTactile Recovery Slope Angle.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Terminology2.1 Definitions:2.1.1 break displacement(Tb)the displacement at contactbreak.2.1.2 break force(Fb)the force at contact break.2.1.3 circuit resistanceelectrical resistance as measuredbetween two test points whose internal contacts,when heldclosed,complete a circuit.2.1.4 closure(make)the event at which a specified resis-tance is achieved.2.1.5 contact breakpoint at which circuit resistance ishigher than specified resistance on return.2.1.6 contact displacement(Tc)the displacement at con-tact closure.2.1.7 contact force(Fc)the force at contact closure.2.1.8 displacementmeasured distance of movement whenmembrane is depressed.2.1.8.1 DiscussionDisplacement is sometimes referred toas“switch travel.”2.1.9 Fmaxan applied force,maximum force measuredprior to or including point(Fmin)(see Fig.1).2.1.9.1 DiscussionSometimes referred to as ActuationForce.2.1.10 Fminan applied force,minimum force seen be-tween Fmax and point at which probe movement ceases.2.1.10.1 DiscussionFmax can equal Fmin.2.1.11 force-displacement hysteresis curverelationshipbetween force applied and displacement of a membrane switchin terms of the actuation and return(recovery).2.1.11.1 DiscussionUsually expressed as a line graph;sometimes referred to as Force-Travel curve(see Fig.1).2.1.12 force factor make(Ffactor)mathematical expres-sion for the change in force between Fmax and Fmin(see Eq7.1.1).2.1.12.1 DiscussionFfactor=0 for non-tactile switch.2.1.13 force factor break(Frfactor)mathematical ex-pression for the change in force between Frmax and Frmin(see Eq 7.1.2).2.1.13.1 DiscussionFrfactor=0 for non-tactile switch.2.1.14 membrane switcha momentary switching device inwhich at least one contact is on,or made of,a flexiblesubstrate.2.1.15 non-tactile switchswitch that does not have atactile response and therefore has a response slope equal tozero because Fmax and Fmin are the same(see Fig.2).2.1.16 return min force(Frmin)minimum force seen dur-ing return cycle before reaching Frmax.2.1.17 return max force(Frmax)maximum force mea-sured during return cycle after achieving Frmin.2.1.18 specified resistancemaximum allowable resistanceas measured between two terminations whose internal switchcontacts are held closed to complete a circuit.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved Dec.1,2010.Published January 2011.Originallyapproved 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 States1 2.1.19 switch teasing(break)the displacement measure-ment on the force-displacement curve between contact break(Fb)and return force(Frmin).2.1.20 switch teasing(make)the displacement measure-ment on the force-displacement curve between contact force(Fc)and minimum force(Fmin).2.1.21 tactile actuation slope angle(TAS)mathematicalrepresentation of the functional relationship between displace-ment and force of a tactile switch on the closure stroke of theswitch(see Eq 7.1.5 and Fig.3).2.1.22 tactile recovery slope angle(TRS)mathematicalrepresentation of the functional relationship between displace-ment and force of a tactile switch on the contact break strokeof the switch(see Eq 7.1.6 and Fig.4).2.1.23 tactile responsea physical sensation,caused by asudden collapse or snapback,or both,of a membrane switch.2.1.24 tactile switcha switch