ASTM F2359-04

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F2359–04
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 3.4 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.
luminous color of a backlit membrane switch. As written, it
However, it may be sufficient and practical to apply the test
applies to a fully assembled switch. For specific purposes, it
either to a subassembly only, or to the illumination only, in
can be applied to partially assembled switches, with the
which case the results apply to that layer only and the net effect
understanding that the results pertain only to the partial
on the fully assembled device must be extrapolated.
assembly and will be modified as the further assembly pro-
ceeds.
4. Interferences
2. Terminology 4.1 Tests on incomplete assemblies give results appropri-
ately to that state of assembly. Specifically, later application of
2.1 Definitions:
a graphic overlay may alter the results.
2.1.1 graphic overlay—a graphically illustrated layer, often
4.2 Failure to fill the sampling aperture of the colorimeter
attached to the top side of the switch assembly for protection,
will bias the results in a way which is not necessarily
cosmetic purposes, or to indicate the location and function of
predictable and for which compensation cannot be made.
the switch keys.
4.3 Since every light source changes characteristics as it
2.1.2 illumination layer—a layer in the construction of a
ages, it must be recognized that the results apply to a particular
membrane switch, which may or may not be a physically
interval in the lifetime of the system. Characterization of the
distinct layer which contains or supports the source of illumi-
aging properties may be addressed in a separate test method.
nation for the switch. Examples are a flexible layer containing
4.4 Perpendicularity—Since the angular distribution of
light emitting diodes (LEDs), often either the top or bottom
emitted light can be altered by any material through which it
layer of the switch, or a flexible layer of electroluminescent
passes, it is important that photometer be held perpendicular to
(EL) material, often a distinct and separate layer added at
the area to be sampled.
assembly.
4.5 Temperature—Since the performance of many light
2.1.3 membrane switch—a momentary switching device, in
sources can vary with temperature, it is important to allow the
which at least one contact is on, or made of, a flexible
UUT to thermally stabilize, if necessary, and then record the
substrate.
ambient temperature at which the measurements are made.
2.1.4 UUT—unit under test.
4.6 Ambient Light—Stray light sources will be detected by
3. Significance and Use
the photometer and will affect UUT color measurement. It is
important to measure the ambient light before illuminating the
3.1 Illuminationofaswitchorofcertainfeaturesofaswitch
UUT. This ambient light reading should be zero or as close to
often has a functional purpose and must meet specification to
zero as possible.
satisfy the functional requirements of the switch.
3.2 Illumination of the switch can be affected by variations
5. Apparatus
in the quality and design of the overlay and its application.
5.1 A working or mounting surface to hold and support the
3.3 This test method addresses only the optical and visual
UUT assembly, providing electrical access to the termination
appearance of the switch and not its electrical function.
regionfromwhichtheilluminationistobepoweredandvisible
access to the regions at which the luminous color is to be
This test
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