1、Designation: F2592 10F2592 16Standard 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
2、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 force displacement characteristics of a membrane switch.1.1.1 This test method r
3、eplaces Test Method F1570 (Tactile Ratio). Tactile Actuating Slope Angle and Tactile Recovery SlopeAngle 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 metho
4、d 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 ofActuation Force, Displacement, Contact Force,Return Force, and Tactile Actuating Slope Ang
5、le 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 responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimita
6、tions prior to use.2. Terminology2.1 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 resistanceelectrical resistance as measured between two test points whose internal contacts, when held closed,complete a circ
7、uit.2.1.4 closure (make)the event at which a specified resistance is achieved.2.1.5 contact breakpoint 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、.8 displacementmeasured distance of movement when membrane is depressed.2.1.8.1 DiscussionDisplacement is sometimes referred to as “switch travel.”2.1.9 Fmaxan applied force, maximum force measured prior to or including point (Fmin) (see Fig. 1).2.1.9.1 DiscussionSometimes referred to as Actuation F
9、orce.2.1.10 Fminan applied force, minimum force seen between Fmax and point at which probe movement ceases.2.1.10.1 Discussion1 This test method is under the jurisdiction ofASTM Committee F01 on Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane SwitchesPrintedElectronic
10、s.Current edition approved Dec. 1, 2010May 1, 2016. Published January 2011May 2016. Originally approved in 2006. Last previous edition approved in 20092010 asF2592-09.-10. DOI: 10.1520/F2592-10.10.1520/F2592-16.This document is not an ASTM standard and is intended only to provide the user of an ASTM
11、 standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the standard as published b
12、y ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Fmax can equal Fmin.2.1.11 force-displacement hysteresis curverelationship between force applied and displacement of a membrane switch in
13、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 expression for the change in force between Fmax and Fmin (see Eq 7.1.1).2.1.12.1 DiscussionFfacto
14、r = 0 for non-tactile switch.2.1.13 force factor break (Frfactor)mathematical expression for the change in force between Frmax and Frmin (see Eq7.1.2).2.1.13.1 DiscussionFrfactor = 0 for non-tactile switch.2.1.14 membrane switcha momentary switching device in which at least one contact is on, or mad
15、e of, a flexible substrate.2.1.15 non-tactile switchswitch that does not have a tactile response and therefore has a response slope equal to zero becauseFmax and Fmin are the same (see Fig. 2).2.1.16 return min force (Frmin)minimum force seen during return cycle before reaching Frmax.2.1.17 return m
16、ax force (Frmax)maximum force measured during return cycle after achieving Frmin.NOTE 1Area 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 1622.1.18 specified resistancemaxim
17、um allowable resistance as measured between two terminations whose internal switchcontacts are held closed to complete a circuit.2.1.19 switch teasing (break)the displacement measurement on the force-displacement curve between contact break (Fb) andreturn force (Frmin).2.1.20 switch teasing (make)th
18、e displacement measurement on the force-displacement curve between contact force (Fc) andminimum force (Fmin).2.1.21 tactile actuation slope angle (TAS)mathematical representation of the functional relationship between displacementand force of a tactile switch on the closure stroke of the switch (se
19、e Eq 7.1.5 and Fig. 3).2.1.22 tactile recovery slope angle (TRS)mathematical representation of the functional relationship between displacementand force of a tactile switch on the contact break stroke of the switch (see Eq 7.1.6 and Fig. 4).2.1.23 tactile responsea physical sensation, caused by a su
20、dden collapse or snapback, or both, of a membrane switch.2.1.24 tactile switcha switch that has a tactile response and therefore has a response slope less than zero (negative slope).2.1.25 TfmaxDisplacement at Fmax.2.1.26 TfminDisplacement at Fmin.2.1.27 Tfrmaxdisplacement at Frmax.2.1.28 Tfrmindisp
21、lacement at Frmin.2.1.29 travel factor make (Tfactor)mathematical expression for the change in displacement between Tfmax and Tfmin (seeEq 7.1.3).2.1.29.1 DiscussionTfactor = 0 for non-tactile switch.FIG. 2 Non-Tactile Switch Force DisplacementF2592 163FIG. 3 Tactile Actuation Slope Angle TASFIG. 4
22、Tactile Recovery Slope Angle TRSF2592 1642.1.30 travel factor break (Trfactor)mathematical expression for the change in displacement between Trfmax and Trfmin(see Eq 7.1.4).2.1.30.1 DiscussionTrfactor = 0 for non-tactile switch.3. Significance and Use3.1 The force and displacement values when conver
23、ted to a slope are useful in quantifying the differences in tactile responseamong membrane switches.3.2 Specified resistance is useful to manufacturers and users when designing membrane switch interface circuitry.3.3 Actuation force and contact force are useful to manufacturers and users in determin
24、ing the suitability, reference andaesthetics of a membrane switch in a given application.3.4 The tendency of a switch to make or break electrical contact at unexpected moments during closure or release can be a signof a poor design. The degree of teasing can range from a simple annoyance to a failur
25、e of critical control process.3.5 The amount of switch sensitivity or teasing can also be a result of poor surface conductivity that will prevent an electricalevent even when switch poles are in partial contact.4. Interferences4.1 Results compared between a manual measurement system and automated me
26、asurement system can be significant based onthe response time of operator and the equipment. As a result, it is recommended that automated equipment is used that has theproper resolution and time response to make proper measurement.4.2 The switch sample should be mounted on a rigid support in order
27、to get a more accurate representation of the force anddisplacement (travel). Rigid support must not deflect more than 0.0001 in. under a load that is two times the largest Fmax valueexpected.5. Apparatus5.1 Test Probe, made of non-elastic material with a circular flat tip with a diameter approximate
28、ly 50 % of the minimum spaceropening for a non-tactile switch or 50 % of the tactile element diameter for a tactile switch.5.2 Device, to hold probe securely and provide perpendicular movement into and away from switch under test.5.3 Monitoring Device, suitable to continually detect all displacement
29、 and force data points with the following recommendedresolution of 0.00025 in. (0.0064 mm) and 10 ms time response.5.4 Test Surface, flat, smooth, unyielding, and larger than switch under test. Test surface must not deflect more than 0.0001in.under a load that is two times the largest Fmax value exp
30、ected.5.5 Resistance Measuring Device, that is, ohm meter. The device should not apply a voltage outside the operating range of theswitch contacts.NOTE 1Area between forward and return curves is the difference in work by the tactile mechanism showing hysterisis in the tactile system.6. Procedure6.1
31、Pre-Test Setup:6.1.1 Ensure that the test specimen is mounted securely to a rigid substrate.6.1.2 Connect switch terminals to resistance measuring device.6.1.3 Position test probe over center of the designated area of switch.6.1.4 Position probe until tip is just above top surface of switch without
32、touching.6.1.5 Precondition switch until approximation of steady state condition is achieved. (note this will typically occur between 5to 25 cycles, and it is recommended that the instrument and test probe be used when practical.)6.2 In-Process Test6.2.1 Begin by activating test probe movement down
33、at a rate not to exceed 131.3 mm/s.6.2.1.1 Record Force-Displacement data to obtain, at minimum, values for Fmax, Fmin, Fc,Tc,Tfmax, and Tfmin. Other datapoints optional.6.2.2 Continue movement until probe stops orpredetermined force above whenF contact closure max is achieved.6.2.3 Reverse directio
34、n of test probe until it is no longer touching the top surface of the switch, and record Fb,Tb,Frmin, Frmax,Tfrmin, Tfrmax.F2592 1657. 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 Break:Frfactor = (Frm
35、ax 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 Slope Angle:(TAS) =
36、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 Displacement switch te
37、ase (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,8.1.3 Barometri
38、c 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 - optional,8.1.
39、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 tease (break)optiona
40、l, andF2592 1668.1.29 Force switch tease (break)optional.8.1.30 Specified resistance.9. Precision and Bias9.1 The precision and bias of this test method are under investigation10. Keywords10.1 force-displacement curve; membrane switch; sensitivity; switch tease; tactile acuation force; tactile actua
41、tion slope angle;tactile ratio; tactile recovery slope; tactile response slope; 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 a
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