ASTM F2360-04
(Test Method)Standard Test Method for Determining Luminance of a Membrane Switch Backlit with Diffuse Light Source
Standard Test Method for Determining Luminance of a Membrane Switch Backlit with Diffuse Light Source
SIGNIFICANCE AND USE
Illumination of a switch or of certain features of a switch often has a functional purpose and must meet specification to satisfy the functional requirements of the switch.
Illumination of the switch can be affected by variations in the quality and design of the overlay and its application.
This test method addresses only the optical and visual appearance of the switch and not its electrical function.
This test method is non-destructive.
If this test method is applied to the entire switch assembly, the results can be applied to the whole device. However, it may be sufficient and practical to apply the test either to a subassembly only, or to the illumination layer only, in which case the results apply to that layer only and the net effect on the fully assembled device must be calculated, extrapolated, or otherwise inferred.
SCOPE
1.1 This test method covers procedures for determining the luminance of a backlit membrane switch. As written, it applies to a fully assembled switch. For specific purposes, it can be applied to partially assembled switches with the understanding that the results pertain only to the partial assembly and will be modified as the further assembly proceeds.
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Designation:F2360–04
Standard Test Method for
Determining Luminance of a Membrane Switch Backlit with
Diffuse Light Source
This standard is issued under the fixed designation F 2360; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.4 This test method is non-destructive.
3.5 If this test method is applied to the entire switch
1.1 This test method covers procedures for determining the
assembly, the results can be applied to the whole device.
luminance of a backlit membrane switch.As written, it applies
However, it may be sufficient and practical to apply the test
to a fully assembled switch. For specific purposes, it can be
either to a subassembly only, or to the illumination layer only,
applied to partially assembled switches with the understanding
in which case the results apply to that layer only and the net
that the results pertain only to the partial assembly and will be
effect on the fully assembled device must be calculated,
modified as the further assembly proceeds.
extrapolated, or otherwise inferred.
2. Terminology
4. Interferences
2.1 Definitions:
4.1 Tests on incomplete assemblies give results appropriate
2.1.1 graphic overlay—a graphically illustrated layer often
to that state of assembly. Specifically, later application of a
attached to the topside (or first surface) of the switch assembly
graphic overlay may alter the results.
for protection, cosmetic purposes, or to indicate the location
4.2 Failure to fill the sampling aperture of the photometer
and function of the switch keys.
will bias the results in a way which is not necessarily
2.1.2 illumination layer—a layer in the construction of a
predictable.
membrane switch, which may or may not be a physically
4.3 Since every system of illumination changes characteris-
distinct layer which contains or supports the source of illumi-
tics as it ages, it must be recognized that the results apply to a
nation for the membrane switch. Examples are a flexible layer
particular interval in the lifetime of the system. Characteriza-
containing light emitting diodes (LEDs), often either the top or
tion of the aging properties may be addressed in a separate test
bottom layer of the switch, or a flexible layer of electrolumi-
method.
nescent (EL) material, often a distinct and separate layer added
4.4 Perpendicularity—Since the angular distribution of
at assembly.
emitted light can be altered by any material through which it
2.1.3 membrane switch—a momentary switching device, in
passes, it is important that the photometer be held perpendicu-
which at least one contact is on, or made of, a flexible
lar to the area to be sampled.
substrate.
4.5 Temperature—Since the performance of many light
2.1.4 UUT—unit under test.
sources can vary with temperature, it is important to allow the
3. Significance and Use UUT to thermally stabilize, if necessary, and then record the
ambient temperature at which the measurements are made.
3.1 Illuminationofaswitchorofcertainfeaturesofaswitch
4.6 Ambient Light—Stray light sources will be detected by
often has a functional purpose and must meet specification to
the photometer and will affect the UUT luminance measure-
satisfy the functional requirements of the switch.
ment. It is important to measure the ambient light before
3.2 Illumination of the switch can be affected by variations
illuminating the UUT. This ambient light reading should be
in the quality and design of the overlay and its application.
zero or as close to zero as possible.
3.3 This test method addresses only the optical and visual
appearance of the switch and not its electrical function.
5. Apparatus
5.1 A working or mounting surface to hold and support the
This test method is under the jurisdiction of ASTM
...
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