Standard Test Method for Determining the Luminance Curve of an Electroluminescent Lamp at Ambient Conditions

SIGNIFICANCE AND USE
To provide a standardized test method that can be used for a valid comparison of luminance time curves, color changes and cosmetic changes between lamps of various designs, fabrication techniques, and sources.
SCOPE
1.1 This test method establishes the procedures for determining the visible performance change, which is defined by luminance, color and cosmetic appearance of an electroluminescent lamp during operation over an extended time.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

Status
Historical
Publication Date
30-Apr-2009
Technical Committee
Drafting Committee
Current Stage
Ref Project

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ASTM F2771-09 - Standard Test Method for Determining the Luminance Curve of an Electroluminescent Lamp at Ambient Conditions
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:F2771–09
Standard Test Method for
Determining the Luminance Curve of an Electroluminescent
Lamp at Ambient Conditions
This standard is issued under the fixed designation F2771; 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 3.1.4 time to half luminance (THL), n—the elapsed operat-
ing time over which the luminance of a lamp maintained under
1.1 This test method establishes the procedures for deter-
constant power conditions is reduced to 50 % of its initial
mining the visible performance change, which is defined by
value.
luminance, color and cosmetic appearance of an electrolumi-
3.1.5 membrane switch, n—a momentary switching device,
nescent lamp during operation over an extended time.
in which at least one contact is on, or made of, a flexible
1.2 This standard does not purport to address all of the
substrate.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 This test method includes an initial measurement of the
bility of regulatory limitations prior to use.
luminance, color, and appearance of a lamp when powered
2. Referenced Documents with a specified voltage source. After initial characterization,
the lamp is maintained under the same power conditions for an
2.1 ASTM Standards:
extended interval in a controlled environment designed to
F1595 Practice for Viewing Conditions for Visual Inspec-
interfere minimally with the operating characteristics of the
tion of Membrane Switches
lamp. The luminance, color and appearance of the lamps under
F2359 Test Method for Determining Color of a Membrane
test are measured and recorded at a predetermined schedule
Switch Backlit with Diffuse Light Source
throughout the test (initially the intervals are shorter to capture
F2360 Test Method for Determining Luminance of a Mem-
the rapid rate of change and longer as the test progresses). One
brane Switch Backlit with Diffuse Light Source
output of the measurement is to identify the time of operation
3. Terminology
by which the measured luminance is reduced to half that
recorded at the initial characterization.
3.1 Definitions:
3.1.1 luminance, n—measure of the brightness or luminous
5. Significance and Use
intensity of light, usually expressed in units of candelas per
2 2
5.1 To provide a standardized test method that can be used
square metre (cd/m ) or foot lamberts. 1 fL = 3.426 cd/m .
foravalidcomparisonofluminancetimecurves,colorchanges
3.1.2 luminance curve, n—a graphical representation of the
and cosmetic changes between lamps of various designs,
variation of luminance with time (implicitly under unvarying
fabrication techniques, and sources.
operating conditions).
3.1.3 electroluminescent lamp (EL lamp), n—essentially a
6. Interferences
capacitor structure with phosphor and a dielectric sandwiched
6.1 Humidity—Performance characteristics can be skewed
between electrodes, one of which is transparent to allow light
with the change of humidity.
to escape. Application of an ac voltage across the electrodes
6.2 Temperature—Performance characteristics can be
generates a charging field within the phosphor, which causes it
skewed with the change of temperature.
to emit light.
6.3 Power—Performance characteristics can be skewed
with variations in the voltage, frequency and waveform of the
This test method is under the jurisdiction of ASTM Committee F01 on
power applied to the lamp.
Electronics and is the direct responsibility of Subcommittee F01.18 on Membrane
Switches.
7. Apparatus
Current edition approved May 1, 2009. Published June 2009. DOI: 10.1520/
F2771-09.
7.1 Power source capable of providing an appropriate ac
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
voltage and frequency. For example, operation at 110 6 3
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
VRMS,at400 610Hz,whichisprevalentintheindustry.Any
Standards volume information, refer to the standard’s Document Summary page on
deviation shall be reported.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2771–09
7.2 Luminance measurement equipment as specified in Test 11.2.2 Identify test area that is blemish free for initial
Method F2360. measurements.
7.3 Color measurement equipment as specified in Test
11.2.3 Before each measurement, inspect the lamp surface
Method F2359. following Test Method F1595 to identify cosmetic b
...

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