4.1 Application of an EL lamp (or other diffuse lighting source) to illuminate a device has a functional purpose and must meet specifications to satisfy the functional requirements of the device.

4.2 Illumination of the device or application can be affected by variations in the quality, efficiency, and design of the lamp and any attendant mounting or shading fixtures.

4.3 This test method addresses only the optical and visual appearance of the lamp and not its electrical function.

4.4 This test method is non-destructive.

4.5 This test method is described for application to the illumination layer in which case the results apply to that layer only. However, it may be desirable and practical to apply the test to a further assembly or to a fully assembled device with built in illumination. In such a case, the results refer specifically to the subassembly or the entire device respectively.

1.1 This test method covers procedures for determining the uniformity of the luminance of an electroluminescent (EL) lamp. While written specifically for the purpose of evaluating EL devices, which are intrinsically very uniform, it can be applied (judiciously) to the measurement of any diffuse, essentially planar, light source. For specific purposes, it can be applied to partially assembled devices into which the illumination is installed (such as a membrane switch) as a diagnostic for the performance of the entire device. In such a case it must be understood that the results pertain only to the partial assembly and will be modified as the further assembly proceeds.

1.2 The method is to take a 2-dimensional set of measurements, sampling the surface of the unit under test with appropriate density. The method is restricted to measuring luminance only, since variations in color will also show as luminance non-uniformity especially in any photoptically calibrated measuring device.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 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.