Overview
IEC 62595-2-2:2018 specifies standard measurement conditions and measuring methods for determining the electrical and optical performance of white-LED light bars used in LCD backlight units (BLUs). It defines measurement configuration, required instruments, and test-reporting elements to ensure repeatable, traceable evaluation of LED light bars used in display lighting systems.
Key topics and technical requirements
- Measurement scope
- Electrical parameters, luminance distribution profiles, chromaticity and colour uniformity, and test reporting.
- Measuring configuration
- Recommended setup includes a diffuser plate, device-under-test (DUT) mounting (MCPCB/LED array), and a Light Measuring Device (LMD) positioned at defined distances.
- Light Measuring Devices
- Luminance meter: must comply with CIE photopic sensitivity; spot or imaging meters are acceptable. Calibration, dynamic range, stray-light handling, linearity, and FOV are required checks.
- Spectroradiometer: camera lens and viewfinder required; wavelength range 380–780 nm, spectral bandwidth ≤ 5 nm, wavelength accuracy ≤ 0.3 nm; equipment must be calibrated.
- Colorimeter: must comply with CIE 1931 tristimulus values; can be used for luminance and relative colour uniformity but not for absolute colour quantities.
- Measurement conditions
- Standard electrical driving, warm-up time, dark-room environment, thermal conditions, mechanical alignment, and positioning accuracy (orthogonal two-axis sample stage).
- Defined quantities and reporting
- Letter symbols and measurement quantities (e.g., luminance profiles L(x,0), luminance non-uniformity NU, CIE 1931/CIE 1976 chromaticity coordinates, maximum chromaticity difference Δu’v’).
- Guidance for 2D luminance maps, axis profiles, and required test-report elements.
Practical applications and users
- Who uses IEC 62595-2-2:
- LED light-bar manufacturers, BLU/system integrators, display module suppliers
- R&D and optical engineers working on LCD backlights
- Test laboratories, quality assurance, and compliance teams
- Instrument manufacturers developing luminance meters, spectroradiometers, and colorimeters
- Practical benefits:
- Enables consistent, repeatable measurements of brightness and colour uniformity for BLU components
- Improves supplier-vendor communication by defining effective area and reporting formats
- Supports product specification, performance verification, and comparative benchmarking
Related standards
- IEC 62595-1-2 - Terminology and letter symbols (series reference)
- IEC 62595-2-1:2016 - Electro-optical measuring methods of LED backlight unit
- ISO 11664-3, ISO/CIE 11664-5 - Colorimetry references
- ISO 19476 - Guidance on luminance and luminance-meter performance (informative)
Keywords: IEC 62595-2-2, LED light bars, LCD BLU, measuring methods, luminance meter, spectroradiometer, colorimeter, chromaticity, luminance distribution, BLU testing.