ASTM F2359-04(2011)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: F2359 − 04 (Reapproved 2011)
Standard Test Method for
Determining Color of a Membrane Switch Backlit with
Diffuse Light Source
This standard is issued under the fixed designation F2359; 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.
1. Scope 3.2 Illumination of the switch can be affected by variations
in the quality and design of the overlay and its application.
1.1 This test method covers procedures for determining the
luminous color of a backlit membrane switch. As written, it 3.3 This test method addresses only the optical and visual
applies to a fully assembled switch. For specific purposes, it appearance of the switch and not its electrical function.
can be applied to partially assembled switches, with the
3.4 This test method is non-destructive.
understanding that the results pertain only to the partial
3.5 If this test method is applied to the entire switch
assembly and will be modified as the further assembly pro-
assembly, the results can be applied to the whole device.
ceeds.
However, it may be sufficient and practical to apply the test
1.2 The values stated in SI units are to be regarded as
either to a subassembly only, or to the illumination only, in
standard. No other units of measurement are included in this
which case the results apply to that layer only and the net effect
standard.
on the fully assembled device must be extrapolated.
2. Terminology
4. Interferences
2.1 Definitions:
4.1 Tests on incomplete assemblies give results appropri-
2.1.1 graphic overlay—a graphically illustrated layer, often
ately to that state of assembly. Specifically, later application of
attached to the top side of the switch assembly for protection,
a graphic overlay may alter the results.
cosmetic purposes, or to indicate the location and function of
4.2 Failure to fill the sampling aperture of the colorimeter
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 and for which compensation cannot be made.
membrane switch, which may or may not be a physically
4.3 Since every light source changes characteristics as it
distinct layer which contains or supports the source of illumi-
ages, it must be recognized that the results apply to a particular
nation for the switch. Examples are a flexible layer containing
interval in the lifetime of the system. Characterization of the
light emitting diodes (LEDs), often either the top or bottom
aging properties may be addressed in a separate test method.
layer of the switch, or a flexible layer of electroluminescent
(EL) material, often a distinct and separate layer added at
4.4 Perpendicularity—Since the angular distribution of
assembly.
emitted light can be altered by any material through which it
passes, it is important that photometer be held perpendicular to
2.1.3 membrane switch—a momentary switching device, in
the area to be sampled.
which at least one contact is on, or made of, a flexible
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
UUT to thermally stabilize, if necessary, and then record the
3. Significance and Use
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 UUT color measurement. It is
satisfy the functional requirements of the switch.
important to measure the ambient light before illuminating the
UUT. This ambient light reading should be zero or as close to
1 zero as possible.
This test method is under the jurisdiction of ASTM Committee F01 on
Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane
Switches. 5. Apparatus
Current edition approved July 1, 2011. Published August 2
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