MIL-PRF-22885 Switches, Push Button, Illuminated, General Specification ForThis specification covers the general requirements for manually operated illuminated push button switches, switch assemblies \(see 6.4.1\), and associated modular subassemblies. As used in this specification, the term "switches" should include the associated modular subassemblies, including switches, indicator lights, actuators, lenses, color filters, panel seals, barriers, and so forth.

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MIL-PRF-22885H

4.7.34 Illuminated colors (see 3.39). The chromaticity shall be determined by spectrographic or visual means, as

specified below. Unless otherwise specified (see 3.1), lamps used for chromaticity testing shall have a calibrated

mean spherical candle power of .34 �.02 for T-1-3/4 lamps and .15 �.02 for T-1 lamps.

Method I: Spectrophotometer - flat slab: Chromaticity shall be determined using a spectrophotometer, flat

slab material of the same density and thickness of the shaped filter, and necessary calibration filters.

Method II: Spectroradiometric - Chromaticity shall be determined using a spectroradiometer, a complete

illuminated push button assembly, calibrated lamps of specified color temperature, and necessary calibration

filters.

Method III: Visual comparator - Chromaticity shall be determined by a color comparator, necessary high and

low limit plastic or glass filters of known chromaticity, and calibrated light sources of specific color

temperature.

4.7.35 Luminance (see 3.40). Unless otherwise specified (see 3.1), all luminance measurements shall be taken in

completely dark surroundings. All readings shall be point readings and averaged. Luminance readings shall be

taken by a calibrated photoelectric photometer. Alternately, readings may be taken with a calibrated video

photometer. In this case, readings may be point readings or be the average of the total illuminated area of the

character. Luminance may be taken without the legend installed if the legend material is not a significant part of the

illumination system. Unless otherwise specified (see 3.1), lamps used for luminance testing shall have a calibrated

mean spherical candlepower of .34 � .02 for T-1 3/4 lamps and .15 � .02 for T-1 lamps. For points of measurements

NOTE: Test panel shall be located in the chamber wall at least 1 meter from any corner and at least 1 meter from

floor and ceiling.

FIGURE 8. Block diagram of switch shielding efficiency test.