1、Designation: F2592 10Standard 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
2、. 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 T
3、est 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 Te
4、st 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
5、 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
6、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 clos
7、ure (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 displaceme
8、ntmeasured 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 Fmina
9、n 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
10、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
11、(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 switchswit
12、ch 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 seenduring return cycle before reaching Frmax.2.1.17 return max force (Frmax)maximum force mea-sured during return cycl
13、e after achieving Frmin.2.1.18 specified resistancemaximum allowable resistanceas measured between two terminations whose internal switchcontacts are held closed to complete a circuit.2.1.19 switch teasing (break)the displacement measure-ment on the force-displacement curve between contact break(Fb)
14、 and return force (Frmin).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 appro
15、ved in 2009 as F2592-09. DOI:10.1520/F2592-10.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.1.20 switch teasing (make)the displacement measure-ment on the force-displacement curve between contact force(Fc) and minimum force (Fmin
16、).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
17、 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 that has a tactile res
18、ponseand therefore has a response slope less than zero (negativeslope).2.1.25 TfmaxDisplacement at Fmax.2.1.26 TfminDisplacement at Fmin.2.1.27 Tfrmaxdisplacement at Frmax.2.1.28 Tfrmindisplacement at Frmin.2.1.29 travel factor make (Tfactor)mathematical ex-pression for the change in displacement be
19、tween Tfmax andTfmin (see Eq 7.1.3).2.1.29.1 DiscussionTfactor = 0 for non-tactile switch.2.1.30 travel factor break (Trfactor)mathematical ex-pression for the change in displacement between Trfmax andTrfmin (see Eq 7.1.4).2.1.30.1 DiscussionTrfactor = 0 for non-tactile switch.3. Significance and Us
20、e3.1 The force and displacement values when converted to aslope are useful in quantifying the differences in tactileresponse among membrane switches.3.2 Specified resistance is useful to manufacturers and userswhen designing membrane switch interface circuitry.3.3 Actuation force and contact force a
21、re useful to manu-facturers and users in determining the suitability, reference andaesthetics of a membrane switch in a given application.3.4 The tendency of a switch to make or break electricalcontact at unexpected moments during closure or release canbe a sign of a poor design. The degree of teasi
22、ng can rangefrom a simple annoyance to a failure of critical control process.3.5 The amount of switch sensitivity or teasing can also bea result of poor surface conductivity that will prevent anelectrical event even when switch poles are in partial contact.4. Interferences4.1 Results compared betwee
23、n a manual measurement sys-tem and automated measurement system can be significantNOTEArea 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 LoopF2592 102based on the response time of ope
24、rator and the equipment. Asa result, it is recommended that automated equipment is usedthat has the proper resolution and time response to make propermeasurement.4.2 The switch sample should be mounted on a rigid supportin order to get a more accurate representation of the force anddisplacement (tra
25、vel). Rigid support must not deflect more than0.0001 in. under a load that is two times the largest Fmax valueexpected.5. Apparatus5.1 Test Probe, made of non-elastic material with a circularflat tip with a diameter approximately 50 % of the minimumspacer opening for a non-tactile switch or 50 % of
26、the tactileelement diameter for a tactile switch.5.2 Device, to hold probe securely and provide perpendicu-lar movement into and away from switch under test.5.3 Monitoring Device, suitable to continually detect alldisplacement and force data points with the following recom-mended resolution of 0.000
27、25 in. (0.0064 mm) and 10 ms timeresponse.5.4 Test Surface, flat, smooth, unyielding, and larger thanswitch under test. Test surface must not deflect more than0.0001in. under a load that is two times the largest Fmax valueexpected.5.5 Resistance Measuring Device, that is, ohm meter. Thedevice should
28、 not apply a voltage outside the operating rangeof the switch contacts.NOTE 1Area between forward and return curves is the difference inwork by the tactile mechanism showing hysterisis in the tactile system.6. Procedure6.1 Pre-Test Setup:6.1.1 Ensure that the test specimen is mounted securely to ari
29、gid substrate.6.1.2 Connect switch terminals to resistance measuringdevice.6.1.3 Position test probe over center of the designated areaof switch.6.1.4 Position probe until tip is just above top surface ofswitch without touching.6.1.5 Precondition switch until approximation of steadystate condition i
30、s achieved. (note this will typically occurbetween 5 to 25 cycles, and it is recommended that theinstrument and test probe be used when practical.)6.2 In-Process Test6.2.1 Begin by activating test probe movement down at arate not to exceed 13 mm/s.FIG. 2 Non-Tactile Switch Force DisplacementF2592 10
31、3FIG. 3 Tactile Actuation Slope Angle TASFIG. 4 Tactile Recovery Slope Angle TRSF2592 1046.2.1.1 Record Force-Displacement data to obtain, at mini-mum, values for Fmax, Fmin, Fc, Tc, Tfmax, and Tfmin. Otherdata points optional.6.2.2 Continue movement until probe stops or when contactclosure is achie
32、ved.6.2.3 Reverse direction of test probe until it is no longertouching the top surface of the switch, and record Fb, Tb,Frmin, Frmax, Tfrmin, Tfrmax.7. Calculations7.1 Calculate Slopes:7.1.1 Force Factor Make:Ffactor = (Fmax Fmin)/Fmax7.1.1.1 Ffactor = 0 for non-tactile switch7.1.2 Force Factor Bre
33、ak:Frfactor = (Frmax Frmin)/Frmax7.1.2.1 Frfactor = 0 for non-tactile switch7.1.3 Travel Factor Make:Tfactor = (Tfmin Tfmax)/Tfmin7.1.3.1 Tfactor = 0 for non-tactile switch7.1.4 Travel Factor Break:Trfactor = (Tfrmin Tfrmax)/Tfrmin7.1.4.1 Trfactor = 0 for non-tactile switch7.1.5 Tactile Actuation Sl
34、ope Angle:(TAS) = tan1(Ffactor/Tfactor) (see Fig. 3)7.1.5.1 TAS does not exist for non-tactile switch (0/0).7.1.6 Tactile Recovery Slope Angle:(TRS) = tan1(Frfactor/Trfactor) (see Fig. 4)7.1.6.1 TRS does not exist for non-tactile switch (0/0).7.2 Determine switch teasing at makeoptional.7.2.1 Displa
35、cement switch tease (make) = Tc Tfmin.7.2.2 Force switch tease (make) = Fc Fmin.7.3 Determine switch teasing at breakoptional.7.3.1 Displacement switch tease (break) = Tb Tfrmin.7.3.2 Force switch tease (break) = Fb Frmin.8. Report8.1 Report the following information:8.1.1 Temperature,8.1.2 Humidity
36、,8.1.3 Barometric pressure,8.1.4 Probe material and diameter,8.1.5 Description of test apparatus,8.1.6 Fmax,8.1.7 Fmin,8.1.8 Fc,8.1.9 Fb,8.1.10 Frmax,8.1.11 Frmin,8.1.12 Tfmax,8.1.13 Tfmin,8.1.14 Tfrmax,8.1.15 Tfrmin,8.1.16 Ffactor,8.1.17 Tfactor,8.1.18 Frfactor,8.1.19 Trfactor,8.1.20 TAS,8.1.21 TRS
37、 - optional,8.1.22 Part number or description of switch, or both,8.1.23 Date of test,8.1.24 Force-displacement curve, optional,8.1.25 Speed of probe (if using automated equipment).8.1.26 Displacement switch tease (make)optional,8.1.27 Force switch tease (make)optional,8.1.28 Displacement switch teas
38、e (break)optional, and8.1.29 Force switch tease (break)optional.9. Precision and Bias9.1 The precision and bias of this test method are underinvestigation10. Keywords10.1 force-displacement curve; membrane switch; sensitiv-ity; switch tease; tactile acuation force; tactile actuation slopeangle; tact
39、ile ratio; tactile recovery slope; tactile responseslope; tactile recovery slope angle; travelASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determinat
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