ASTM F1661-2008 Standard Test Method for Determining the Contact Bounce Time of a Membrane Switch.pdf

1、Designation: F 1661 08Standard Test Method forDetermining the Contact Bounce Time of a MembraneSwitch1This standard is issued under the fixed designation F 1661; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi

2、sion. 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 determination of the contactbounce time of a membrane switch.1.2 This standard does not purport to

3、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. Referenced Documents2.1 ASTM Standards:2D 2240 Tes

4、t Method for Rubber PropertyDurometerHardnessF 2592 Test Method for Measuring the Force-Displacementof a Membrane SwitchF 1680 Test Method for Determining Circuit Resistance of aMembrane Switch3. Terminology3.1 Definitions:3.1.1 contact bounceintermittent contact opening andcontact closure that may

5、occur after switch operation.3.1.2 contact bounce time (break), TCBBthe time periodmeasured from the first instant VMis equal to the SUTV untilit constantly remains below the SLTV after the last instant itrises above the SUTV. If VMdoes not rise above SUTV duringthe time interval, TCBB= 0, (see Fig.

6、 1).3.1.3 contact bounce time (make), TCBMthe time periodmeasured from the first instant VMis equal to the SLTV untilit constantly remains above the SUTV after the last instant itfalls below the SLTV. If VMdoes not fall below SLTV duringthe time interval, TCBM= 0, (see Fig. 2).3.1.4 lower transition

7、 voltage, LTVthe voltage at whichthe switched logic device transitions to an “off” state.3.1.5 membrane switcha momentary switching device inwhich at least one contact is on, or made of, a flexiblesubstrate.3.1.6 resistor, load, RLload resistance in series withswitch under test.3.1.7 specified lower

8、 transition voltage, SLTVminimumallowable LTV.3.1.8 specified upper transition voltage, SUTVminimumallowable UTV.3.1.9 upper transition voltage, UTVthe voltage at whichthe switched logic device transitions to an 88on” state.1This test method is under the jurisdiction of ASTM Committee F01 onElectron

9、ics and is the direct responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved Nov. 1, 2008. Published December 2008. Originallyapproved in 1995. Last previous edition approved in 2002 as F 1661 96(2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org,

10、orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.FIG. 1 Contact Bounce on Switch BreakFIG. 2 Contact Bounce on Switch Make1Copyright ASTM International, 100 Barr Harbor Drive, PO B

11、ox C700, West Conshohocken, PA 19428-2959, United States.3.1.10 voltage, measured, VMvoltage measured acrossload Resistor (RL) by the oscilloscope and measured on itsscreen or voltage measured across the switch under test whena contact bounce measuring device is used.4. Significance and Use4.1 Conta

12、ct bounce time is essential to manufacturers andusers when designing interface circuitry because it specifies thetime delay necessary in the decoder circuitry to avoid any falsesignals caused by contact bounce. Allowing for time delaymakes the switch operation considerably more reliable.5. Interfere

13、nce5.1 The following parameters may affect the results of thistest:5.1.1 Mechanical probe materials (hardness) and speed willaffect results.6. Apparatus6.1 Test Probe, built to either of the configuration shown inFig. 3 and Fig. 4 are acceptable but must be made of an inertelastomeric material with

14、a hardness number equivalent toA/45 6 5 as measured in accordance with Test MethodD 2240. Test probes that do not meet the above criteria must befully specified and recorded.6.2 Test Surfaceflat, smooth, unyielding, and larger thanswitch under test.6.3 Oscilloscope, with recording capabilities and p

15、owersupply, or suitable contact bounce time measuring instrument.6.4 Device, which will consistently move probe into andaway from the switch at a controlled speed. Also capable ofapplying a specified force.7. Procedure7.1 Pretest Setup:7.1.1 Determine Fmax or Fc (whichever is greater) per TestMethod

16、 F 2592.7.1.2 Determine switch resistance (RS) per Test MethodF 1680.7.1.3 Secure switch on test surface.7.1.4 Connect switch terminals as shown in Fig. 5 so that:RL5 10 to 100 times RS7.1.5 Adjust oscilloscope to initial settings as follows:7.1.5.1 One half to 1.0 V/cm vertical, and7.1.5.2 Two to 3

17、 ms/cm horizontal.7.1.5.3 Set SUTV per Table 1 if known. If not known,default SUTV will be 2.0 VDC.7.1.5.4 Set SLTV per Table 1 if known. If not known,default SLTV will be 0.9 VDC.7.1.6 Adjust power supply to test voltage per Table 1 ifknown. If not known, default test voltage will be 5 VDC.7.1.7 Ad

18、just to rising waveform when measuring TCBM.7.1.8 Adjust to falling waveform when measuring TCBB.7.2 In Process Test (TCBM):7.2.1 Activate and release switch with test probe at thepredetermined force (7.1.6) at a cycling rate not to exceed 3cycles per second.7.2.2 Record TCBM(see Fig. 2) from oscill

19、oscope display.7.2.3 Repeat 7.2.1-7.2.3 four more times.7.3 In Process Test (TCBB):7.3.1 Activate and release switch with test probe at thepredetermined force (7.1.6) at a cycling rate not to exceed 3cycles per second.7.3.2 Record TCBB(see Fig. 1) from oscilloscope display.7.3.3 Repeat 7.3.1-7.3.3 f

20、our more times.8. Report8.1 Report the following information:8.1.1 Temperature,8.1.2 Humidity,8.1.3 Barometric pressure,8.1.4 Specified resistance (RS),8.1.5 Load resistance (RL) (if using oscilloscope method),8.1.6 TCBM(min), TCBM(max),8.1.7 TCBB(min), TCBB(max),8.1.8 Part number or description of

21、switch under test, orboth,8.1.9 Date of test,FIG. 3 Test Probe OptionFIG. 4 Test Probe OptionFIG. 5 Test Setup OptionF 1661 082FIG. 1 Table 1F 1661 0838.1.10 Description of oscilloscope or contact bounce timemeasuring instrument,8.1.11 SUTV for oscilloscope method, UTV for contactbounce time measuri

22、ng instrument method,8.1.12 SLTV for oscilloscope method, LTV for contactbounce time measuring instrument method,8.1.13 Completely describe means of activating switch,include details such as:8.1.13.1 Size, shape and durometer of probe,8.1.13.2 Actuation force,8.1.13.3 Velocity of probe, and8.1.13.4

23、Any other relevant information needed to duplicatetest.9. Precision and Bias9.1 The precision and bias of this test method are underinvestigation.10. Keywords10.1 contact bounce; membrane switchASTM International takes no position respecting the validity of any patent rights asserted in connection w

24、ith 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 tec

25、hnical 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 addressed to ASTM International Headquarters. Your comments will receive careful considera

26、tion at a meeting of theresponsible technical committee, 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 H

27、arbor 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 1661 084