1、Designation:F236008(Reapproved 2015)1Standard Test Method forDetermining Luminance of a Membrane Switch Backlit withDiffuse Light Source1This standard is issued under the fixed designation F2360;the number immediately following the designation indicates the year oforiginal adoption or,in the case of
2、 revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEThe spelling of interlaboratory in 8.1 was corrected editorially in June 2015.1.Scope1.1 This test method c
3、overs procedures for determining theluminance of a backlit membrane switch.As written,it appliesto a fully assembled switch.For specific purposes,it can beapplied to partially assembled switches with the understandingthat the results pertain only to the partial assembly and will bemodified as the fu
4、rther assembly proceeds.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 this standa
5、rd 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 graphic overlaya graphically illustrated layer oftenattached to the topside(or first surface)of the switch assemblyfor protection,cosmet
6、ic purposes,or to indicate the locationand function of the switch keys.2.1.2 illumination layera layer in the construction of amembrane switch,which may or may not be a physicallydistinct layer which contains or supports the source of illumi-nation for the membrane switch.Examples are a flexible lay
7、ercontaining light emitting diodes(LEDs),often either the top orbottom layer of the switch,or a flexible layer of electrolumi-nescent(EL)material,often a distinct and separate layer addedat assembly.2.1.3 membrane switcha momentary switching device,inwhich at least one contact is on,or made of,a fle
8、xiblesubstrate.2.1.4 UUTunit under test.3.Significance and Use3.1 Illumination of a switch or of certain features of a switchoften has a functional purpose and must meet specification tosatisfy the functional requirements of the switch.3.2 Illumination of the switch can be affected by variationsin t
9、he quality and design of the overlay and its application.3.3 This test method addresses only the optical and visualappearance of the switch and not its electrical function.3.4 This test method is non-destructive.3.5 If this test method is applied to the entire switchassembly,the results can be appli
10、ed to the whole device.However,it may be sufficient and practical to apply the testeither to a subassembly only,or to the illumination layer only,in which case the results apply to that layer only and the neteffect on the fully assembled device must be calculated,extrapolated,or otherwise inferred.4
11、.Interferences4.1 Tests on incomplete assemblies give results appropriateto that state of assembly.Specifically,later application of agraphic overlay may alter the results.4.2 Failure to fill the sampling aperture of the photometerwill bias the results in a way which is not necessarilypredictable.4.
12、3 Since every system of illumination changes characteris-tics as it ages,it must be recognized that the results apply to aparticular interval in the lifetime of the system.Characteriza-tion of the aging properties may be addressed in a separate testmethod.4.4 PerpendicularitySince the angular distri
13、bution ofemitted light can be altered by any material through which itpasses,it is important that the photometer be held perpendicu-lar to the area to be sampled.4.5 TemperatureSince the performance of many lightsources can vary with temperature,it is important to allow the1This test method is under
14、 the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.18 on PrintedElectronics.Current edition approved June 1,2015.Published July 2015.Originally approvedin 2004.Last previous edition approved in 2008 as F2360-08.DOI:10.1520/F2360-08R15E01.Copyri
15、ght ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 UUT to thermally stabilize,if necessary,and then record theambient temperature at which the measurements are made.4.6 Ambient LightStray light sources will be detected bythe photometer and will af
16、fect the UUT luminance measure-ment.It is important to measure the ambient light beforeilluminating the UUT.This ambient light reading should bezero or as close to zero as possible.5.Apparatus5.1 A working or mounting surface to hold and support theUUT assembly,providing electrical access to the terminationregion from which the illumination is to be powered and visibleaccess to the regions at which the luminance is to be measured.5.2 A power supply providing appropriate and adequatepower to driv