1、Designation: F 2592 07aStandard 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 revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 replac
3、es Test Method F 1570. TheTactile Response Slope has been determined to be a morerepresentative characterization of a tactile sensation.1.1.2 This test method replaces Test Method F 1682.1.1.3 This test method replaces Test Method F 1597.1.1.4 This test method replaces Test Method F 1997.1.2 Force d
4、isplacement 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 all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of
5、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 resis
6、tanceelectrical 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.
7、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 whena membrane switch is depressed.2.1.9 Fmaxan applied force, maximum force measuredprior to or including point (Fmin) (see Fig. 1).2.
8、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 memb
9、rane 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 membrane switcha momentary switching device inwhich at least one contact is on, or made of, a flexiblesubstrate.2.1.13 non-t
10、actile 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).2.1.14 return min force (Frmin)minimum force seenduring return cycle before reaching Frmax.2.1.15 return max force (Frmax)maximum force mea-sured d
11、uring return cycle after achieving Frmin.2.1.16 specified resistancemaximum allowable resistanceas measured between two terminations whose 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
12、contact break(Fb) and return force (Frmin).2.1.18 switch teasing (make)the displacement measure-ment on the force-displacement curve between contact force(Fc) and minimum force (Fmin).2.1.19 tactile recovery sloperate of change of return forcewith respect to displacement, as measured between TFrmina
13、nd TFrmax (see Fig. 3).2.1.20 tactile responsea physical sensation, caused by asudden collapse or snapback, or both, of a membrane switch.2.1.21 tactile response sloperate of change of appliedforce with respect to displacement, as measured betweenTfmax and Tfmin (see Figs. 3 and 4).2.1.22 tactile sw
14、itcha switch that has a tactile responseand therefore has a response slope less than zero (negativeslope).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 July 1, 2007.
15、 Published August 2007. Originallyapproved in 2006. Last previous edition approved in 2007 as F 2592-07.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.1.23 TfmaxDisplacement at Fmax.2.1.24 TfminDisplacement at Fmin.2.1.25 Tfrmaxdi
16、splacement at Frmax.2.1.26 Tfrmindisplacement at Frmin.3. Significance and Use3.1 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 designin
17、g membrane switch interface circuitry.3.3 Actuation force and contact force are 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
18、 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 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 sw
19、itch poles are in partial contact.4. Interferences4.1 Results compared between a manual measurement sys-tem and automated measurement system 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 acc
20、urate representation of the force anddisplacement (travel).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 the tactileelement diameter for a tactile switch.5.2 Device,
21、 to hold probe securely and provide perpendicu-lar movement into and away from switch under test.5.3 Monitoring Device, suitable to detect 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. The
22、device should not apply a voltage outside the operating rangeof the switch contacts.6. 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.NOTEArea between forward and return curves is th
23、e difference in work by the tactile mechanism showing hysterisis in the tactile system.FIG. 1 Force Displacement Hysterisis LoopF 2592 07a26.1.3 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 Pr
24、econdition switch until approximation of steadystate condition is 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 exc
25、eed 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 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 t
26、op 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. Calculations7.1 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
27、(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 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 Rep
28、ort 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 of test apparatus,8.1.6 Fmax (avg),8.1.7 Fmin (avg),8.1.8 Fc (avg),8.1.9 Fb (avg),8.1.10 Frmax (avg),8.1.11 Frmin (avg),8.1.12 Tfmax (avg),8.1.13 Tfmin (avg),F
29、IG. 2 Non-Tactile Switch Force DisplacementF 2592 07a38.1.14 Tactile Response Slope (avg)must report units ofmeasure for force-displacement for example, newtons/mm,8.1.15 Tactile Recovery Slope (avg), optionalmust reportunits of measure for force-displacement for example,newtons/mm,8.1.16 Part numbe
30、r 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 (make)optional,8.1.24 Displacement sw
31、itch 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; tactilerecovery slope; tactile response slope; travelFIG. 3 Tactile Response
32、Slope (TRS)FIG. 4 Tactile Response Slope CalculationF 2592 07a4ASTM 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 determination of the validity of any such
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35、air 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).F 2592 07a5
