1、Designation: F 1661 96 (Reapproved 2002)Standard 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
2、 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.1. Scope1.1 This test method covers the determination of the contactbounce time of a membrane switch.1.2 This standard d
3、oes 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. Referenced Documents2.1 ASTM St
4、andards:D 2240 Test Method for Rubber PropertyDurometerHardness23. Terminology3.1 Definitions:3.1.1 contact bounceintermittent contact opening andcontact closure that may occur after switch operation.3.1.2 contact bounce time (break), TCBBthe time periodmeasured from the first instant VMis equal to
5、the SLTV untilthe first instant it again falls below the SLTV after the lastinstant it rises above the SUTV. If VMdoes not rise aboveSUTV during the time interval, TCBB= 0, (see Fig. 1).3.1.3 contact bounce time (make), TCBMthe time periodmeasured from the first instant VMis equal to the SUTV untilt
6、he first instant it again rises above the SUTV after the lastinstant it falls below the SLTV. If VMdoes not fall below SLTVduring the time interval, TCBM= 0, (see Fig. 2).3.1.4 lower transition voltage, LTVthe voltage at whichthe switched logic device transitions to an “off” state.3.1.5 membrane swi
7、tcha 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 transition voltage, SLTVminimumallowable LTV.3.1.8 specified resistance, RSmaximum allowable resis-tance m
8、easured between two terminations whose internalswitch contacts, when held closed, complete a circuit.3.1.9 specified upper transition voltage, SUTVminimumallowable UTV.3.1.10 upper transition voltage, UTVthe voltage at whichthe switched logic device transitions to an 88on” state.3.1.11 voltage, meas
9、ured, 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 Contact bounce time is essential to manufacturers andusers when designing interfac
10、e circuitry because it specifies thetime delay necessary in the decoder circuitry to avoid any false1This 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 Dec. 10, 1996. Publ
11、ished February 1997. Originallypublished as F 1661 95. Last previous edition F 1661 95.2Annual Book of ASTM Standards, Vol 09.01.FIG. 1 Contact Bounce on Switch BreakFIG. 2 Contact Bounce on Switch Make1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
12、9, United States.signals caused by contact bounce. Allowing for time delaymakes the switch operation considerably more reliable.5. Interference5.1 The following parameters may affect the results of thistest:5.1.1 If a human finger is used in place of a mechanicalprobe the results are more varied and
13、 larger sample sizesshould be used, and5.1.2 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 a hardness number equivalent
14、 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 powersupply, or suitable cont
15、act 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.CONTACT BOUNCE TIME MEASURINGINSTRUMENT METHOD7. Procedure7.1 Pre Test Setup:7.1.1 Secure switch on test surface.7.1.2 Con
16、nect switch terminals as shown in Fig. 5 or asspecified by manufacturer.7.2 In Process Test (TCBMand TCBB)Contact BounceTime Measuring Instrument Method:7.2.1 Activate switch in a consistent, repeatable, controlledmanner. If a mechanical probe is used apply force with apreselected value (to be repor
17、ted later).7.2.2 Record TCBM.7.2.3 Release switch after desired interval in a consistent,repeatable, controlled manner (to be reported later).7.2.4 Record TCBB.7.2.5 Repeat 7.2.1-7.2.4 four more times.OSCILLOSCOPE METHOD8. Procedure8.1 Pretest Setup:8.1.1 Secure switch on test surface.8.1.2 Connect
18、switch terminals as shown in Fig. 6 so that:RL5 10 to 100 times RS8.1.3 Adjust oscilloscope to initial settings as follows:8.1.3.1 One half to 1.0 V/cm vertical, and8.1.3.2 Two to 3 ms/cm horizontal.8.1.4 Adjust to rising waveform when measuring TCBM.8.1.5 Adjust to falling waveform when measuring T
19、CBB.8.2 In Process Test (TCBM):8.2.1 Activate switch in a consistent, repeatable, controlledmanner. If a mechanical probe is used apply force with apreselected value (to be reported later).8.2.2 Release switch.8.2.3 Record TCBM(see Fig. 2) from oscilloscope display.8.2.4 Repeat 8.2.1-8.2.3 four more
20、 times.8.3 In Process Test (TCBB):8.3.1 Start test with switch activated.8.3.2 Release switch in a consistent, repeatable, controlledmanner (to be reported later).8.3.3 Record TCBBfrom oscilloscope display.FIG. 3 Test Probe OptionFIG. 4 Test Probe OptionFIG. 5 Test Setup OptionFIG. 6 Test Setup Opti
21、onF 166128.3.4 Repeat 8.3.1-8.3.3 four more times.9. Report9.1 Report the following information:9.1.1 Temperature,9.1.2 Humidity,9.1.3 Barometric pressure,9.1.4 Specified resistance (RS),9.1.5 Load resistance (RL) (if using oscilloscope method),9.1.6 TCBM(min), TCBM(max),9.1.7 TCBB(min), TCBB(max),9
22、.1.8 Part number or description of switch under test, orboth,9.1.9 Date of test,9.1.10 Description of oscilloscope or contact bounce timemeasuring instrument,9.1.11 SUTV for oscilloscope method, UTV for contactbounce time measuring instrument method,9.1.12 SLTV for oscilloscope method, LTV for conta
23、ctbounce time measuring instrument method,9.1.13 Completely describe means of activating switch,include details such as:9.1.13.1 Size, shape and durometer of probe,9.1.13.2 Actuation force,9.1.13.3 Velocity of probe, and9.1.13.4 Any other relevant information needed to duplicatetest.10. Precision an
24、d Bias10.1 The precision and bias of this test method are underinvestigation.11. Keywords11.1 contact bounce; membrane switchASTM 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 ex
25、pressly 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 revi
26、sed, 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 consideration at a meeting of theresponsible technical committee, which you ma
27、y 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).F 16613
