ASTM_F_1570_-_01e1.pdf

Designation:F 1570 01e1Standard Test Method forDetermining the Tactile Ratio of a Membrane Switch1This standard is issued under the fixed designation F 1570;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(e)indicates an editorial change since the last revision or reapproval.e1NOTEThe equation in 6.2 was corrected editorially in December 2001.1.Scope1.1 This test method covers the determination of the tactileresponse of a membrane switch as defined by tactile ratio.1.2 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 Fmaxmaximum force measured prior to or includingpoint(Fmin)(see Fig.1 and Fig.2).2.1.2 Fminminimum force seen between Fmaxand point atwhich probe movement ceases.2.1.2.1 DiscussionFmaxcan equal Fmin.2.1.3 force-travel curverelationship between force ap-plied and travel of a membrane switch.2.1.3.1 DiscussionUsually expressed as a line graph(seeFig.1 and Fig.2).2.1.4 membrane switcha momentary switching device inwhich at least one contact is on,or made of,a flexiblesubstrate.2.1.5 non-tactile switcha switch assembly that has atactile ratio equal to zero.2.1.6 tactile ratioa measure of tactile response(see Eq6.2).2.1.7 tactile responsea physical sensation,caused by asudden collapse or snapback,or both,of a membrane switch.2.1.7.1 DiscussionThe amount of tactile response is de-termined by the equation shown in 6.2.2.1.8 tactile switcha switch assembly that provides atactile ratio greater than zero.2.1.9 travelmeasured distance of movement when amembrane switch is depressed.3.Significance and Use3.1 The tactile ratio is useful in quantifying the feel of amembrane switch.Factors other than tactile ratio may affectthe“feel”of a tactile switch.3.2 Always report the tactile ratio as a function of measuredFmax.This is important because it is possible to have the sametactile ratio for different values of Fmax.4.Apparatus4.1 Test Probe,made of nonelastic material with shape andsize to be specified.4.2 Device,to hold probe securely and provide perpendicu-lar movement into and away from switch under test.4.3 Monitoring Device,suitable to detect Fmaxand Fmin.4.4 Test Surface,flat,smooth,unyielding,and larger thanswitch under test.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 Sept 10,2001.Published November 2001.Originallypublished as F 1570 94.Last previous edition F 1570 94.FIG.1 Typical Tactile ForceTravel Curve1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.5.Procedure5.1 Pre-Test Setup:5.1.1 Secure switch on test surface.5.1.1.1 Precondition switch by depressing manually 25times.5.1.2 Position test probe over desired area of switch.5.1.3 Position probe until tip is just above top surface ofswitch without touching.5.2 In-Process Test:5.2.1 Begin by activating test probe movement down at arate not to exceed 13 mm/s.5.2.1.1 During downward probe movement record FmaxandFmin.5.2.2 Continue movement until probe movement stops orwhen force on probe is a minimum of 110%of Fmax.5.2.3 Reverse direction of test probe until it is no longertouching the top surface of the switch.5.2.4 Repeat 5.2.1 thru 5.2.3 four times.6.Calculations6.1 Determine the average of five readings for FmaxandFmin.6.2 Tactile ratio is determined by the following equation:Tactile ratio 5Fmaxavg!2 Fminavg!Fmaxavg!3 1007.Report7.1 Report the following information:7.1.1 Temperature,7.1.2 Humidity,7.1.3 Barometric pressure,7.1.4 Shape and size of probe,7.1.5 Fmax(avg),7.1.6 Fmin(avg),7.1.7 Tactile ratio,7.1.8 Description of probe holding fixture and monitoringdevice,7.1.9 Part number or description of switch,or both,7.1.10 Date of test,and7.1.11 Force-travel curve(optionalsee Fig.1 and Fig.2).8.Precision and Bias8.1 The precision and bias of this test method are underinvestigation.9.Keywords9.1 membrane switch;tactile ratioASTM 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 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 andif not revised,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be