ASTM F2360-08(2015)e1

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: F2360 − 08 (Reapproved 2015)
Standard Test Method for
Determining Luminance of a Membrane Switch Backlit with
Diffuse Light Source
This standard is issued under the fixed designation F2360; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—The spelling of interlaboratory in 8.1 was corrected editorially in June 2015.
1. Scope 2.1.4 UUT—unit under test.
1.1 This test method covers procedures for determining the
3. Significance and Use
luminance of a backlit membrane switch.As written, it applies
to a fully assembled switch. For specific purposes, it can be
3.1 Illuminationofaswitchorofcertainfeaturesofaswitch
applied to partially assembled switches with the understanding
often has a functional purpose and must meet specification to
that the results pertain only to the partial assembly and will be
satisfy the functional requirements of the switch.
modified as the further assembly proceeds.
3.2 Illumination of the switch can be affected by variations
1.2 The values stated in SI units are to be regarded as
in the quality and design of the overlay and its application.
standard. No other units of measurement are included in this
3.3 This test method addresses only the optical and visual
standard.
appearance of the switch and not its electrical function.
1.3 This standard does not purport to address all of the
3.4 This test method is non-destructive.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.5 If this test method is applied to the entire switch
priate safety and health practices and determine the applica-
assembly, the results can be applied to the whole device.
bility of regulatory limitations prior to use.
However, it may be sufficient and practical to apply the test
either to a subassembly only, or to the illumination layer only,
2. Terminology
in which case the results apply to that layer only and the net
effect on the fully assembled device must be calculated,
2.1 Definitions:
2.1.1 graphic overlay—a graphically illustrated layer often extrapolated, or otherwise inferred.
attached to the topside (or first surface) of the switch assembly
for protection, cosmetic purposes, or to indicate the location 4. Interferences
and function of the switch keys.
4.1 Tests on incomplete assemblies give results appropriate
2.1.2 illumination layer—a layer in the construction of a
to that state of assembly. Specifically, later application of a
membrane switch, which may or may not be a physically
graphic overlay may alter the results.
distinct layer which contains or supports the source of illumi-
4.2 Failure to fill the sampling aperture of the photometer
nation for the membrane switch. Examples are a flexible layer
will bias the results in a way which is not necessarily
containing light emitting diodes (LEDs), often either the top or
predictable.
bottom layer of the switch, or a flexible layer of electrolumi-
nescent (EL) material, often a distinct and separate layer added 4.3 Since every system of illumination changes characteris-
at assembly. tics as it ages, it must be recognized that the results apply to a
particular interval in the lifetime of the system. Characteriza-
2.1.3 membrane switch—a momentary switching device, in
tion of the aging properties may be addressed in a separate test
which at least one contact is on, or made of, a flexible
method.
substrate.
4.4 Perpendicularity—Since the angular distribution of
emitted light can be altered by any material through which it
This test method is under the jurisdiction of ASTM Committee F01 on
passes, it is important that the photometer be held perpendicu-
Electronics and is the direct responsibility of Subcommittee F01.18 on Printed
lar to the area to be sampled.
Electronics.
CurrenteditionapprovedJune1,2015.PublishedJuly2015.Originallyapproved
4.5 Temperature—Since the performance of many light
in 2004. Last previous edition approved in 2008 as F2360-08. DOI: 10.1520/F2360-
08R15E01. sources can vary with temperature, it is important to allow the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F2360 − 08 (2015)
UUT to thermally stabilize, if necessary, and then record the 7.1.3 Luminance measured,
ambient temperature at which the measurements are made. 7.1.4 Power conditions for the illumination device,
7.1.5 Location and size of the sample area or areas,
4.6 Ambient Light—Stray light sources will be detected by
7.1.6 Photometer used, sample settings, calibration status,
the photometer and will affect the UUT luminance measure-
and the size of the sampling aperture,
ment. It is important to measure the ambient light before
7.1.7 Ambient temperature, and
illuminating the UUT. This ambient light reading should be
7.1.8 Date of test.
zero or as close to zero as possible.
8. Precision and Bias
5. Apparatus
8.1 The precision of this test method is based on an
5.1 A working or mounting surface to hold and support the
interlaboratory study of F2360-04, conducted in 2006. Each of
UUT assembly, providing electrical access to the termination
six
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