1、Designation: F 2360 08Standard Test Method forDetermining Luminance of a Membrane Switch Backlit withDiffuse Light Source1This standard is issued under the fixed designation F 2360; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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.1. Scope1.1 This test method covers procedures for determining theluminance of a backlit membrane switch. As written, i
3、t 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 further assembly proceeds.1.2 The values stated in SI units are to be regarded asstanda
4、rd. 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 standard to establish appro-priate safety and health practices and determine the applic
5、a-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, cosmetic purposes, or to indicate the locationand function of the switch keys.2.1.2
6、 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 layercontaining light emitting diodes (LEDs), often either the top orbottom l
7、ayer 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 flexiblesubstrate.2.1.4 UUTunit under test.3. Significance and Use3.
8、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 the quality and design of the overlay and its application.3.3 Thi
9、s 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 applied to the whole device.However, it may be sufficient and practi
10、cal 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. Interferences4.1 Tests on incomplete assemblies give resul
11、ts 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.4.3 Since every system of illumination changes characteris-
12、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 distribution ofemitted light can be altered by any material t
13、hrough 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 theUUT to thermally stabilize, if necessary, and then record theambient temperatur
14、e at which the measurements are made.4.6 Ambient LightStray light sources will be detected bythe photometer and will affect the UUT luminance measure-ment. It is important to measure the ambient light before1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the di
15、rect responsibility of Subcommittee F01.18 on MembraneSwitches.Current edition approved July 1, 2008. Published August 2008. Originallyapproved in 2004. Last previous edition approved in 2004 as F 2360-04.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-
16、2959, United States.illuminating 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
17、visibleaccess to the regions at which the luminance is to be measured.5.2 A power supply providing appropriate and adequatepower to drive the illumination device(s) with appropriateconnector(s). This should be specified as dc or ac, with voltageand power level given, and ideally should be switched.5
18、.3 A calibrated device to measure surface luminance (orradiance). This is typically a spot photometer, with a fairlycompact sampling aperture (1-cm diameter at the minimumworking distance). Output should be in foot lamberts (candelaper meter squared). Alternatively, a radiometer may be used, oreven
19、a video photometer, but cognizance must be maintainedof the output units and calibration.5.4 Ameans to support the luminance measuring instrumentat a fixed distance and orientation to the UUT.5.5 A means to control stray light and prevent it fromentering the aperture of the photometer.6. Procedure6.
20、1 Mount UUT on the working surface with the illuminatedsurface visible.6.2 Attach a switched power source as appropriate to theillumination device set to the design operating point.6.3 Mount the photometer or luminance meter so that theaxis of its field of view is perpendicular to the area of the UU
21、Tto be measured. Ensure that the sampling aperture is filled bythe area to be measured on the UUT.6.4 Measure the stray light level by taking a photometerreading while the UUT luminous source is not powered. If thisvalue is not zero or very close to it, do not proceed, but takesteps to reduce the st
22、ray light present. This may be as simple asreducing the ambient room light or switching the overheadlights off altogether.6.5 Switch on the luminous source in the UUT.6.6 Measure the luminance of the sample area of the UUT.7. Report7.1 Report the following information:7.1.1 State of UUT (assembled o
23、r not),7.1.2 Stray light level,7.1.3 Luminance measured,7.1.4 Power conditions for the illumination device,7.1.5 Location and size of the sample area or areas,7.1.6 Photometer used, sample settings, calibration status,and the size of the sampling aperture,7.1.7 Ambient temperature, and7.1.8 Date of
24、test.8. Precision and Bias8.1 The precision of this test method is based on aninterlaboratoy study of F 2360-04, conducted in 2006. Each ofsix laboratories tested three different types of lamps. A single“test result” represents an individual determination. Everylaboratory produced twelve test result
25、s for each material.28.1.1 RepeatabilityTwo test results obtained within onelaboratory shall be judged not equivalent if they differ by morethan the “r” value for that material; “r” is the intervalrepresenting the critical difference between two test results forthe same material, obtained by the sam
26、e operator using thesame equipment on the same day in the same laboratory.8.1.2 ReproducibiltyTwo test results shall be judged notequivalent if they differ by more than the “R” value for thatmaterial; “R” is the interval representing the difference be-tween two test results for the same material, ob
27、tained bydifferent operators using different equipment in different labo-ratories.8.1.3 Any judgment in accordance with these two state-ments would have an approximate 95 % probability of beingcorrect.8.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining
28、the bias for this testmethod, therefore no statement on bias is being made.8.3 The precision statement was determined through statis-tical examination of 216 results, from six laboratories, on threetypes of lamps. The three types of lamps used are describedbelow:Lamp 1: manufactured by Metromark: co
29、lor: amber (X =0.521, Y = 0.462)Lamp 2: manufactured by Nelson Nameplate: color: green(X = 0.186, Y = 0.449)Lamp 3: manufactured by Durel: color: blue (X = 0.155, Y= 0.204)8.3.1 To judge the equivalency of two test results, it isrecommended to choose the lamp closest in characteristics tothe test la
30、mp.9. Keywords9.1 backlit; colorimeter; diffuse light; electroluminescentmaterial; light emitting diodes; luminance; membrane switch;photometer; radiometer; video photometer2Supporting data are available from ASTM International Headquarters. RequestRR:F01-1019.F2360082ASTM International takes no pos
31、ition 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 responsibil
32、ity.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 addressed to AS
33、TM International Headquarters. Your comments will receive careful consideration 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
34、 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
35、-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 1 Luminance (foot lamberts)Lamp AveragexRepeatability StandardDeviationsrReproducibilityStandard DeviationsRRepeatability LimitrReproducibility LimitR1 2.6140 0.0996 0.4386 0.28 1.232 16.0102 0.3321 1.9016 0.93 5.323 4.4033 0.1878 0.5747 0.53 1.61F2360083
