IEC 62595-2-3:2018

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

IEC 62595-2-3:2018(E) specifies the standard measurement conditions and measuring methods for determining electrical, optical, and electro-optical properties of LED frontlight units (FLUs) for reflective displays.

General Information

• Status: Published
• Publication Date: 07-Feb-2018
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 31.120 - Electronic display devices
• ICS: 31.260 - Optoelectronics. Laser equipment
• Technical Committee: TC 110 - Electronic displays
• Drafting Committee: WG 19 - TC 110/WG 19
• Current Stage: PPUB - Publication issued
• Start Date: 12-Mar-2018
• Completion Date: 08-Feb-2018

Standards Content (Sample)

IEC 62595-2-3 ®
Edition 1.0 2018-02
INTERNATIONAL
STANDARD
Display lighting unit –
Part 2-3: Electro-optical measuring methods for LED frontlight unit
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IEC 62595-2-3 ®
Edition 1.0 2018-02
INTERNATIONAL
STANDARD
Display lighting unit –
Part 2-3: Electro-optical measuring methods for LED frontlight unit

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-5360-1

– 2 – IEC 62595-2-3:2018 © IEC 2018
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms, definitions, abbreviated terms and letter symbols . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 8
3.3 Letter symbols (quantity symbols / unit symbols). 9
4 Measuring devices . 10
4.1 General . 10
4.2 Light measuring device (LMD) . 10
4.2.1 Luminance meter . 10
4.2.2 Spectroradiometer (spectral radiance-meter) . 10
4.2.3 Conoscopic system . 10
4.2.4 Image sensor . 10
4.3 Other devices . 10
4.3.1 Sample stage . 10
4.3.2 Light absorber . 11
5 General measuring conditions . 11
5.1 Standard conditions . 11
5.2 Measurement setup . 11
5.3 Warm-up time . 12
6 Electrical measurement methods . 12
6.1 Conditions . 12
6.2 Current . 12
6.3 Voltage . 12
6.4 Power consumption . 12
7 Optical measurement methods . 13
7.1 General . 13
7.2 Dark room conditions . 13
7.2.1 General . 13
7.2.2 Measurement items under the external lighting condition . 13
7.2.3 Measurement items under the internal lighting condition . 13
7.3 Conditions . 13
7.4 Luminance . 14
7.4.1 General . 14
7.4.2 Procedures . 14
7.5 Angular luminance distribution (ALD) . 15
7.6 Luminance uniformity or non-uniformity . 15
7.7 Spectral power distribution . 16
7.8 Chromaticity . 16
7.9 Colour uniformity . 16
7.10 Angular luminance uniformity . 16
7.11 Angular colour uniformity . 16
7.12 FLU polarization characteristic measurement . 16
7.13 Normal- or inverted-state FLU characteristics . 17
7.14 Optical noise measuring . 17

7.15 Cosmetic quality or perceptual visual quality . 17
Annex A (informative) Optical structure of an FLU. 19
Annex B (informative) Normal-state FLU and inverted-state FLU . 20
Annex C (informative) Angular measurement system . 21
Annex D (informative) Measurement parameters for BRDF and BTDF. 22
D.1 BRDF . 22
D.2 BTDF . 22
Annex E (informative) Determining the polarization state of reflected light on the front
surface of an FLU or transmitted light through the FLU . 24
Annex F (informative) Optical transfer function (OTF) of an FLU . 25
F.1 Optical transfer function evaluation chart . 25
F.2 Example of optical transfer function . 25
Annex G (informative) Sources of optical noise in a normal-state FLU with a reflective
display . 27
Annex H (informative) Formulation of contrast ratio for a reflective display with an
integrated FLU . 28
H.1 Contrast ratio for a reflective display without FLU integration . 28
H.2 Contrast ratio for a reflective display with FLU integration . 28
Annex I (informative) Example of optical noise of an FLU . 29
Bibliography . 30

Figure 1 – Example of light absorber (optical trap) . 11
Figure 2 – Example of measurement setup for a LED FLU . 12
Figure 3 – Illustration of zenith angle θ and azimuth angle ϕ (normal-state FLU) . 14
Figure 4 – Polar coordinate system for frontlight unit measurement . 15
Figure 5 – Example of light polarizing characteristics of an FLU in inverted state . 17
Figure A.1 – Direct edge-lit FLU and indirect edge-lit FLU. 19
Figure B.1 – Normal-state FLU . 20
Figure B.2 – Inverted-state FLU . 20
Figure C.1 –Standard goniometric system . 21
Figure C.2 – Conoscopic system . 21
Figure D.1 – System for measuring the BRDF . 22
Figure D.2 – Measuring the BRDF of an LGP for an FLU . 22
Figure D.3 – System for measuring the BTDF . 23
Figure E.1 – Geometry of a reflected or transmitted polarized light . 24
Figure F.1 – Printed charts on photographic paper for measuring the OTF of the FLU . 25
Figure F.2 – Example of OTF . 26
Figure G.1 – Light rays of an FLU with a reflective LC display . 27
Figure G.2 – Sources of noises in a normal-state FLU with a reflective display . 27
Figure I.1 – Optical signal and noise in a normal-state FLU . 29

Table 1 – Letter symbols (quantity symbols / unit symbols) . 9

– 4 – IEC 62595-2-3:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DISPLAY LIGHTING UNIT –
Part 2-3: Electro-optical measuring methods for LED frontlight unit

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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