1、Designation: F 2592 09Standard Test Method forMeasuring the Force-Displacement of a Membrane Switch1This standard is issued under the fixed designation F 2592; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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
3、 Test Method F 1570 (TactileRatio). Tactile Response Slope better represents the character-ization of tactile sensation, previously called “Tactile Ratio” inTest Method F 1570.1.1.2 This test method replaces Test Method F 1682(Travel).1.1.3 This test method replaces Test Method F 1597 (Ac-tuation an
4、d Contact Force).1.1.4 This test method replaces Test Method F 1997 (SwitchSensitivity).1.2 Force displacement hysterisis loop curve can be used inthe determination of Actuation Force, Displacement, ContactForce, Return Force, and Tactile Response Slope.1.3 This standard does not purport to address
5、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)th
6、e 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
7、.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 Di
8、scussionDisplacement 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
9、 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
10、 Force-Travel curve (see Fig. 1).2.1.12 membrane switcha momentary switching device inwhich at least one contact is on, or made of, a flexiblesubstrate.2.1.13 non-tactile switchswitch that does not have atactile response and therefore has a response slope equal tozero because Fmax and Fmin are the s
11、ame (see Fig. 2).2.1.14 return min force (Frmin)minimum force seenduring return cycle before reaching Frmax.2.1.15 return max force (Frmax)maximum force mea-sured during return cycle after achieving Frmin.2.1.16 specified resistancemaximum allowable resistanceas measured between two terminations who
12、se internal switchcontacts are held closed to complete a circuit.2.1.17 switch teasing (break)the displacement measure-ment on the force-displacement curve between contact break(Fb) and return force (Frmin).2.1.18 switch teasing (make)the displacement measure-ment on the force-displacement curve bet
13、ween contact force(Fc) and minimum force (Fmin).2.1.19 tactile recovery sloperate of change of return forcewith respect to displacement, as measured between TFrminand TFrmax (see Fig. 3).2.1.20 tactile responsea physical sensation, caused by asudden collapse or snapback, or both, of a membrane switc
14、h.2.1.21 tactile response sloperate of change of appliedforce with respect to displacement, as measured betweenTfmax and Tfmin (see Figs. 3 and 4).1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitch
15、es.Current edition approved June 15, 2009. Published July 2009. Originallyapproved in 2006. Last previous edition approved in 2008 as F 2592-08.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.1.22 tactile switcha switch that has a
16、tactile responseand therefore has a response slope less than zero (negativeslope).2.1.23 TfmaxDisplacement at Fmax.2.1.24 TfminDisplacement at Fmin.2.1.25 Tfrmaxdisplacement at Frmax.2.1.26 Tfrmindisplacement at Frmin.3. Significance and Use3.1 The force and displacement values when converted to asl
17、ope 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 are useful to manu-facturers and users in determining the sui
18、tability, 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 teasing can rangefrom a simple annoyance to a failure of critical
19、 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 between a manual measurement sys-tem and automated measurement sys
20、tem can be significantbased on the response time of operator and the equipment.4.2 The switch sample should be mounted on a rigid supportin order to get a more accurate representation of the force anddisplacement (travel).5. Apparatus5.1 Test Probe, made of non-elastic material with a circularflat t
21、ip with a diameter approximately 50 % of the minimumspacer opening for a non-tactile switch or 50 % of 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 detec
22、t Fmax, Fmin,Tfmax, and Tfmin.5.4 Test Surface, flat, smooth, unyielding, and larger thanswitch under test.5.5 Resistance Measuring Device, that is, ohm meter. Thedevice should not apply a voltage outside the operating rangeof the switch contacts.NOTEArea between forward and return curves is the dif
23、ference in work by the tactile mechanism showing hysterisis in the tactile system.FIG. 1 Force Displacement Hysterisis LoopF25920926. Procedure6.1 Pre-Test Setup:6.1.1 Ensure that the test specimen is mounted securely to arigid substrate.6.1.2 Connect switch terminals to resistance measuringdevice.6
24、.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 is achieved. (note this will typically occurbetween 5 to 25 cycles, and it is
25、 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.6.2.1.1 Record Force-Displacement data to obtain, at mini-mum, values for Fmax, Fmin, Fc, Tc, Tfmax, and Tfmin. Otherdata points
26、 optional.6.2.2 Continue movement until probe stops or when contactclosure is achieved.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.6.2.4 Repeat 6.2.1 through 6.2.3 four additional times.7. Calculati
27、ons7.1 Calculate Slopes:7.1.1Tactile Response Slope =Fmax(avg) Fmin(avg)Tfmax(avg) Tfmin(avg)7.1.2Tactile RecoverySlope =Frmax(avg) Frmin(avg)Tfrmax(avg) Tfrmin(avg)7.2 Determine switch teasing at makeoptional.7.2.1 Displacement switch tease (make) = Tc Tfmin.7.2.2 Force switch tease (make) = Fc Fmi
28、n.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,8.1.3 Barometric pressure,8.1.4 Probe material and diameter,8.1.5 Description
29、 of test apparatus,8.1.6 Fmax (avg),8.1.7 Fmin (avg),8.1.8 Fc (avg),FIG. 2 Non-Tactile Switch Force DisplacementF25920938.1.9 Fb (avg),8.1.10 Frmax (avg),8.1.11 Frmin (avg),8.1.12 Tfmax (avg),8.1.13 Tfmin (avg),8.1.14 Tactile Response Slope (avg)for consistency, theunits of measure for Tactile Respo
30、nse Slope will be reported ingrams/mm (1 oz = 28.34 g, 1 in. = 25.4 mm),8.1.15 Tactile Recovery Slope (avg), optionalmust reportunits of measure for force-displacement for example,newtons/mm, for consistency, the units of measure for TactileRecovery Slope will be reported in grams/mm (1 oz = 28.34 g
31、,1 in. = 25.4 mm),8.1.16 Part number or description of switch, or both,8.1.17 Date of test,8.1.18 Force-displacement curve, optional,8.1.19 Tfrmax(avg),8.1.20 Tfrmin(avg),8.1.21 Speed of probe (if using automated equipment).8.1.22 Displacement switch tease (make)optional,8.1.23 Force switch tease (m
32、ake)optional,8.1.24 Displacement switch tease (break)optional, and8.1.25 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 ratio;
33、 tactile recovery slope; tactileresponse slope; travelFIG. 3 Tactile Response Slope (TRS)FIG. 4 Tactile Response Slope CalculationF2592094ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this st
34、andard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years a
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36、 which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F2592095
