IEC 62595-2-3 Display lighting unit-Part 2-3: Electro-optical measuring methods for LED frontlight unit

This part of IEC 62595 specifies the standard measurement conditions and measuring methods for determining electrical, optical, and electro-optical properties of LED frontlight units(FLUs) for reflective displays.

Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

IEC 61747-6-2, Liquid crystal display devices – Part 6-2: Measuring methods for liquid crystal display modules – Reflective type

IEC 62595-1-2, Display lighting unit – Part 1-2: Terminology and letter symbols
IEC 62595-2-1, Display lighting unit – Part 2-1: Electro-optical measuring methods of LED backlight unit
IEC 62679-3-3, Electronic paper displays – Part 3-3: Optical measuring methods for displays with integrated lighting units

Measuring devices

General

The following measuring devices shall be used in this document. The LMD shall be calibrated with the appropriate photometric or spectrometric standards.

Light measuring device (LMD)

Luminance meter

The luminance meter (a spot meter or an imaging meter) shall be equivalent to the human eye.
The equipment shall be calibrated with the luminance standards, and should be carefully checked before measurement, considering the following elements:

– sensitivity of the measured quantity to measuring light;

– errors caused by veiling glare and lens flare (i.e., stray light in optical system);

– timing of data-acquisition, low-pass filtering and aliasing interference fringe effects;

– linearity of detection and data-conversion.
NOTE: ISO/CIE 19476 [10] is available asreference for the LMD evaluation procedures.

Spectroradiometer(spectral radiance-meter)

The wavelength range shall be at least 380 nm to 780 nm and the spectral bandwidth shall be 5 nm or less. The wavelength accuracy shall be 0,3 nm or less. The equipment shall be calibrated with the with the spectrometric standards. The performance should be carefully checked before measurement, considering the same elements as in 4.2.1.

Conoscopic system

The conoscopic system is the angular optical distribution measurement system with Fourier optics. The photometric values, such as luminance, which are obtained by the equipment without any photometric standard calibration shall not be used. The relative values, such as an angular optical distribution and colour uniformity, shall be applied.

Image sensor

The image sensor is constructed from a one-dimensional CCD (CMOS) line sensor or a two-dimensional CCD (CMOS). The image sensor shall be applied for measuring the OTF property of the DUT.
The spatial resolution of the image sensor shall be at least twice as high as that of the DUT.
NOTE Sampling frequency or resolution is double or more that of the chart under measurement to prevent the aliasing interference fringe phenomenon or any countermeasure from eliminating aliasing interference fringe in the measurement.

LISUN following instruments fully meet IEC 62595-2-3 Display lighting unit-Part 2-3: Electro-optical measuring methods for LED frontlight unit:

XYL-VI Luminance Colorimeter

LS-ELF 2D Video Luminance Meter

LSG-1890B High Precision Rotation Luminaire Goniophotometer