IEC 62341-6-2:2015

IEC 62341-6-2 ®
Edition 2.0 2015-12
INTERNATIONAL
STANDARD
colour
inside
Organic light emitting diode (OLED) displays –
Part 6-2: Measuring methods of visual quality and ambient performance
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé Fax: +41 22 919 03 00
CH-1211 Geneva 20 info@iec.ch
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing more than 30 000 terms and
Technical Specifications, Technical Reports and other definitions in English and French, with equivalent terms in 15
documents. Available for PC, Mac OS, Android Tablets and additional languages. Also known as the International
iPad. Electrotechnical Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a More than 60 000 electrotechnical terminology entries in
variety of criteria (reference number, text, technical English and French extracted from the Terms and Definitions
committee,…). It also gives information on projects, replaced clause of IEC publications issued since 2002. Some entries
and withdrawn publications. have been collected from earlier publications of IEC TC 37,

77, 86 and CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: csc@iec.ch.
IEC 62341-6-2 ®
Edition 2.0 2015-12
INTERNATIONAL
STANDARD
colour
inside
Organic light emitting diode (OLED) displays –

Part 6-2: Measuring methods of visual quality and ambient performance

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.260 ISBN 978-2-8322-3026-8

– 2 – IEC 62341-6-2:2015 © IEC 2015
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviations . 7
3.1 Terms and definitions . 7
3.2 Abbreviations . 10
4 Structure of measuring equipment . 10
5 Standard measuring conditions . 10
5.1 Standard measuring environmental conditions . 10
5.2 Standard lighting conditions . 10
5.2.1 Dark-room conditions . 10
5.2.2 Ambient illumination conditions . 11
5.3 Standard setup conditions . 16
5.3.1 General . 16
5.3.2 Adjustment of OLED display modules . 16
5.3.3 Starting conditions of measurements . 16
5.3.4 Conditions of measuring equipment . 16
6 Visual inspection of static images . 17
6.1 General . 17
6.2 Classification of visible defects . 17
6.2.1 General . 17
6.2.2 Reference examples for subpixel defects . 17
6.2.3 Reference example for line defects . 19
6.2.4 Reference example for mura defects . 19
6.3 Visual inspection method and criteria . 20
6.3.1 Standard inspection conditions . 20
6.3.2 Standard inspection method . 21
6.3.3 Inspection criteria . 23
7 Electro-optical measuring methods under ambient illumination . 24
7.1 Reflection measurements . 24
7.1.1 Purpose . 24
7.1.2 Measuring conditions . 24
7.1.3 Measuring the hemispherical diffuse reflectance . 25
7.1.4 Measuring the reflectance factor for a directional light source . 26
7.2 Ambient contrast ratio . 28
7.2.1 Purpose . 28
7.2.2 Measuring conditions . 28
7.2.3 Measuring method . 28
7.3 Display daylight colour . 29
7.3.1 Purpose . 29
7.3.2 Measuring conditions . 29
7.3.3 Measuring method . 29
7.4 Daylight colour gamut volume . 30
7.4.1 Purpose . 30
7.4.2 Measuring conditions . 30
7.4.3 Measuring method . 31

7.4.4 Reporting . 32
Annex A (informative) Measuring relative photoluminescence contribution from
displays . 34
A.1 Purpose . 34
A.2 Measuring conditions . 34
A.3 Measuring the bi-spectral photoluminescence of the display . 34
A.4 Determining the relative PL contribution from the display . 34
Annex B (informative) Diagnostic for observing display luminance dependence from
ambient illumination . 37
B.1 Purpose . 37
B.2 Measuring method . 37
Annex C (informative) Calculation method of daylight colour gamut volume . 38
C.1 Purpose . 38
C.2 Procedure for calculating the colour gamut volume . 38
C.3 Surface subdivision method for CIELAB gamut volume calculation . 40
C.3.1 Purpose . 40
C.3.2 Assumptions . 40
C.3.3 Algorithm . 40
C.3.4 Software example execution . 40
Bibliography . 46

Figure 1 –Example of visual inspection room setup for control of ambient room lighting
and reflections . 11
Figure 2 –Example of measurement geometries for a uniform hemispherical diffuse
illumination condition using an integrating sphere and sampling sphere . 13
Figure 3 – Directional source measurement geometry using an isolated source . 15
Figure 4 – Directional source measurement geometry using a ring light source . 15
Figure 5 – Layout diagram of measurement setup . 16
Figure 6 – Classification of visible defects . 17
Figure 7 – Bright subpixel defects . 18
Figure 8 – Criteria for classifying bright and dark subpixel defects . 19
Figure 9 – Bright and dark line defects . 19
Figure 10 –Sample image of line mura . 20
Figure 11 – Example of spot mura . 20
Figure 12 – Setup condition for visual inspection of electro-optical visual defects . 22
Figure 13 – Shape of scratch and dent defect . 24
Figure 14 –Example of range in colours produced by a given display as represented
by the CIELAB colour space . 32
Figure A.1 – Scaled bi-spectral photoluminescence response from a display . 35
Figure A.2 – Decomposed bi-spectral photoluminescence response from a display . 35
Figure B.1 – Example of display luminance reduction caused by the high illuminance
from a high intensity LED flashlight directed at the display surface . 37
Figure C.1 – Analysis flow chart for calculating the colour gamut volume . 38
Figure C.2 – Graphical representation of the colour gamut volume for sRGB in the
CIELAB colour space . 39

Table 1 – Definitions for types of scratch and dent defects . 24

– 4 – IEC 62341-6-2:2015 © IEC 2015
Table 2 – Eigenvalues M and M for CIE daylight Illuminants D50 and D75 . 26
1 2
Table 3 – Example of minimum colours required for gamut volume calculation of a 3-
primary 8-bit display . 31
Table 4 – Measured tristimulus values for the minimum set of colours (see Table 3)
required for gamut volume calculation under the specified ambient illumination
condition . 33
Table 5 – Calculated white point in the darkened room and daylight ambient condition . 33
Table 6 – Colour gamut volume in the CIELAB colour space . 33
Table C.1 – Tristimulus values of the sRGB primary colours . 39
Table C.2 –Example of sRGB colour set represented in the CIELAB colour space . 39
Table C.3 –Example of sRGB colour gamut volume in the CIELAB colour space . 40

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ORGANIC LIGHT EMITTING DIODE (OLED) DISPLAYS –

Part 6-2: Measuring methods of visual quality and ambient performance

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
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62341-6-2 has been prepared by IEC technical committee 110:
Electronic display devices.
This second edition cancels and replaces the first edition published in 2012. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Contents of 7.4 are changed.
b) Contents and items of Annex C are changed.
c) Annex B is added.
– 6 – IEC 62341-6-2:2015 © IEC 2015
The text of this standard is based on the following documents:
FDIS Report on voting
110/695/FDIS 110/718/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
A list of all parts of the IEC 62341 series, published under the general title Organic light
emitting diode (OLED) displays, can be found on the IEC website.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
ORGANIC LIGHT EMITTING DIODE (OLED) DISPLAYS –

Part 6-2: Measuring methods of visual quality and ambient performance

1 Scope
This part of IEC 62341 specifies the standard measurement conditions and measurement
methods for determining the visual quality and ambient performance of organic light emitting
diode (OLED) display modules and panels. This document mainly applies to colour display
modules.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary (available at
www.electropedia.org)
IEC 61966-2-1, Multimedia systems and equipment – Colour measurement and management
– Part 2-1: Colour management – Default RGB colour space - sRGB
IEC 62341-1-2, Organic light emitting diode (OLED) displays – Part 1-2: Terminology and
letter symbols
CIE 15:2004, Colorimetry
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-845 and
IEC 62341-1-2, as well as the following apply.
3.1.1
visual inspection
means for checking image quality by human visual observation for classification and
comparison against limit sample criteria
3.1.2
subpixel defects
all or part of a single subpixel, the minimum colour element, which is visibly brighter or darker
than surrounding subpixels of the same colour.
Note 1 to entry: Further classifications of subpixel defects are made depending on the number and configuration
of multiple subpixel defects within a region of the display.
Note 2 to entry: For monochromatic displays, the term “dot defect” may be used.

– 8 – IEC 62341-6-2:2015 © IEC 2015
3.1.3
bright subpixel defects
defects in subpixels or dots which are visibly brighter than surrounding subpixels of the same
colour when addressed with a uniform dark or grey background
3.1.4
dark subpixel defects
defects in subpixels or dots which are visibly darker than surrounding subpixels of the same
colour when addressed with a uniform bright background (e.g. > 50 % full screen luminance)
3.1.5
partial subpixel defects
defects in subpixels or dots with part of the emission area obscured such that a visible
difference in brightness is observed in comparison with neighboring subpixels of the same
colour
3.1.6
clustered subpixel defects
subpixel or dot defects gathered in a specified area or within a specified distance
Note 1 to entry: This is also known as “close subpixel defect”.
3.1.7
unstable subpixel
subpixel or dot that changes luminance in an uncontrollable way
3.1.8
pixel shrinkage
reduction in the active emissive area of one or more subpixels (or dots) over time
3.1.9
panel edge shrinkage
reduction in the active emissive area from the edges of the display area over time
3.1.10
line defects
defects in a vertical or horizontal bright or dark line parallel to a row or column observed
against a dark or bright background, respectively
3.1.11
bright line defects
defects in lines appearing bright when displayed with a uniform dark or grey pattern
3.1.12
dark line defects
defects in lines appearing dark when displayed with a uniform bright or grey pattern
3.1.13
mura
visible defects in regions in which the luminance and colour non-uniformity generally vary
more gradually than subpixel level defects
Note 1 to entry: For classification, the maximum dimension should be less than one fourth of the display width or
height.
3.1.14
line mura
variation in luminance consisting of one or more lines extending horizontally or vertically
across all or a portion of the display

3.1.15
colour mura
mura that appears primarily in only one colour channel and results in a local variation of the
white point (or CCT)
3.1.16
spot mura
visible defects in regions in which the luminance variation is larger than a single pixel, and
which appear as a localized slightly darker or brighter region with a smoothly varying edge
3.1.17
mechanical defects
image artefacts arising from defects in protective and contrast enhancement films, coatings,
mechanical fixturing, or other elements within the active area of the display
3.1.18
scratch defect
defect appearing as fine single or multiple lines or scratches, generally light in appearance on
a dark background, and independent of the display state
3.1.19
dent defect
localized spot generally white or grey in appearance on dark background and independent of
the display state
3.1.20
foreign material
defect caused by a foreign material like dust or thread in between the contrast enhancement
films, protective films, or on an emitting surface within the active area of the display
3.1.21
bubble
defect caused by a cavity in or between sealing materials, adhesives, contrast enhancement
films, protective films, or any other films within the active area of the display
3.1.22
ambient contrast ratio
contrast ratio of a display with external natural or artificial illumination incident onto its surface
and which includes indoor illumination from luminaires, or outdoor daylight illumination
3.1.23
colour gamut boundary
surface determined by a colour gamut's extremes
3.1.24
colour gamut volume
single number for characterizing the colour response of a display device in a three-
dimensional colour space
Note 1 to entry: Typically the colour gamut volume is calculated in the CIELAB colour space.
3.1.25
ambient colour gamut volume
single number for characterizing the colour response of a display device, under a defined
ambient illumination condition, in a three-dimensional colour space
Note 1 to entry: Typically the colour gamut volume is calculated in the CIELAB colour space.

– 10 – IEC 62341-6-2:2015 © IEC 2015
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
CCT correlated colour temperature
CIE Commission Internationale de l’Eclairage (International Commission on
Illumination)
CIELAB CIE 1976 (L*a*b*) colour space
DUT device under test
HD high definition
ISO International Organization for Standardization
LED light emitting diode
LMD light measuring device
LTPS low temperature polysilicon
OLED organic light emitting diode
PL photoluminescence
QVGA quarter video graphics array
RGB red, green, blue
SDCM standard deviation of colour matching
sRGB standard RGB colour space as defined in IEC 61966-2-1
TFT thin film transistor
TV television
UV ultraviolet
4 Structure of measuring equipment
The system diagrams and/or operating conditions of the measuring equipment shall comply
with the structure specified in each item.
5 Standard measuring conditions
5.1 Standard measuring environmental conditions
Electro-optical measurements and visual inspection shall be carried out under the standard
environmental conditions, at a temperature of 25 °C ± 3 °C, a relative humidity of 25 % to
85 %, and a pressure of 86 kPa to 106 kPa. When different environmental conditions are used,
they shall be noted in the visual inspection or ambient performance report.
5.2 Standard lighting conditions
5.2.1 Dark-room conditions
The luminance contribution from the background illumination reflected off the test display
shall be ≤ 0,01 cd/m or less than 1/20 the display’s black state luminance, whichever is
lower. If these conditions are not satisfied, then background subtraction is required and it
shall be noted in the ambient performance report. In addition, if the sensitivity of the LMD is
inadequate to measure at these low levels, then the lower limit of the LMD shall be noted in
the ambient performance report.
Unless stated otherwise, the standard lighting conditions shall be the dark-room conditions.

5.2.2 Ambient illumination conditions
5.2.2.1 Ambient illumination conditions for visual inspection
Ambient illumination conditions have a strong impact on the ability of the inspector to resolve
defects, and large variations of light intensity in the visual field can lead to inspector fatigue
and a resulting loss of sensitivity to defects. Refer to ISO 9241-310 for general guidance on

optimal illumination conditions for visual inspection of pixel defects. [1]
For inspector comfort and consistency of inspection conditions, an average ambient
illuminance of between 50 lx and 150 lx is suggested in the inspector’s work area. This
ambient illuminance may be measured, for example, with an illuminance meter facing directly
upward in a horizontal plane at the approximate eye level of the inspector. Care shall be
taken to use diffuse illumination and diffuse textures in the inspection environment, to avoid
glare in the visual field of the inspector. An example of the measurement geometry is shown
in Figure 1.
The display under test shall be placed to avoid direct illumination from ambient room light
sources. In addition, dark light-absorbing materials shall be used to cover specular surfaces
that may be viewed by the inspector in direct reflection from the display surface. In any case,
to limit degradation of the display contrast from ambient light, the ambient illuminance incident
from room light sources on the display surface measured with the display off shall be < 20 lx.
If ambient illuminance at the display surface is > 20 lx, it shall be noted in the visual
inspection report.
No directional
No directional
Diffuse light source
sources
sources
Baffle
Dark, light-
OR
absorbing material
Walls or room
Light shield
furnishings
Inspector
Display device
IEC
Figure 1 –Example of visual inspection room setup
for control of ambient room lighting and reflections
5.2.2.2 Ambient illumination conditions for electro-optical measurements
The following illumination conditions are prescribed for electro-optical measurements of
displays in ambient indoor or outdoor illumination conditions. Ambient indoor room
illumination and outdoor illumination of clear sky daylight, on a display shall be approximated

by the combination of two illumination geometries.[2] Uniform hemispherical diffuse
illumination will be used to simulate the background lighting in a room, or the hemispherical
skylight incident on the display, with sun occluded. A directed source in a dark room will
simulate the effect of directional illumination on a display by a luminaire in a room, or from
direct sunlight.
Some displays can emit photoluminescence (PL) when exposed to certain light. The relative
impact of PL on the reflection measurement can be determined, and is described in Annex A.
An illumination condition that causes a significant reflection measurement error due to the
presence of PL should be treated carefully. If the same illumination spectral distribution and
___________
Numbers in square brackets refer to the Bibliography.

– 12 – IEC 62341-6-2:2015 © IEC 2015
illumination/detection geometry is used for the reflection measurements and the calculation of
ambient contrast ratio and colour, then the PL can be incorporated into the reflection
coefficients. However, if the illumination spectrum used in the calculations is significantly
different, then the reflected component shall be measured separately from the PL component.
The latter case is not addressed in this document.
It should also be confirmed that the display luminance is not sensitive to the ambient
illumination incident on the display. Annex B provides a simple diagnostic to confirm this.
The following illumination conditions shall be used to simulate indoor and outdoor display
viewing environments:
a) Indoor room illumination conditions:
1) Uniform hemispherical diffuse illumination – Use a light source closely approximating
CIE Standard Illuminant A, CIE Standard Illuminant D65, or CIE Standard Illuminant
D50 as defined in CIE 15:2004. The use of an infrared-blocking filter is also
recommended to minimize sample heating from the illuminants. The UV region (< 380
nm) of all light sources shall be cut off. Additional sources may also be used,
depending on the intended application. For spectral measurements, if it can be
demonstrated that the display does not exhibit significant PL (< 1 % PL, see Annex A)
for the selected reference source spectra, then a spectrally smooth broadband source
(such as an approximation to CIE Standard Illuminant A) may be used to measure the
spectral reflectance. Without significant PL, a measurement of the spectral reflectance
using a broad source (like Illuminant A) enables the ambient contrast ratio and colour
to be calculated later for the desired reference spectra (for example D65). The indoor
room contrast ratio shall be calculated using 60 lx of uniform hemispherical illumination
(with specular included) incident on the display surface for a typical TV viewing room,
and 300 lx for an office environment.[3] The actual hemispherical diffuse reflectance
measurement may require higher illumination levels for better measurement accuracy.
The results are then scaled to the required illumination level.
2) Directional illumination – The same source spectra shall be used as with uniform
hemispherical diffuse illumination. If a different spectral source is used, it shall be
noted in the ambient performance report. The presence of significant PL (see Annex A)
shall also be determined for the measured source, and the preceding limitations be
applied when PL is present. The indoor room contrast ratio or colour shall be
calculated using directional illumination of 40 lx incident on the display surface for a
typical TV viewing room, and 200 lx for an office environment with the display in the
vertical orientation. The actual reflectance factor measurement may require higher
illumination levels for better measurement accuracy. The directed source shall be 45°
above the surface normal (θ = 45°, θ = 0°; see Figure 3) and have an angular
s d
subtense of no more than 8°. The angular subtense is defined as the full angle span of
the light source from the centre of the display’s measurement area.
Other illumination levels may be used in addition to those defined above for calculating
the ambient contrast ratio under indoor illumination conditions. However,
approximately 60 % of the total illuminance should be uniform hemispherical diffuse
and 40 % directional illumination.
b) Daylight illumination conditions:
1) Uniform hemispherical diffuse illumination – Use a light source closely approximating
skylight with the spectral distribution of CIE Illuminant D75.[4] Additional CIE daylight
illuminants may also be used, depending on the intended application. An infrared-
blocking filter is recommended to minimize sample heating. The UV region (< 380 nm)
of the light source shall be cut off. For spectral measurements, if it can be
demonstrated that the display does not exhibit significant PL for a 7 500 K correlated
colour temperature (CCT) source, then spectral reflectance factor measurements can
be made using a spectrally smooth broadband source (such as an approximation to
CIE Standard Illuminant A). The contrast ratio or colour can be calculated later for the
D75 illuminant spectra. The daylight contrast ratio and colour shall be calculated using
15 000 lx of uniform hemispherical diffuse illumination (with specular included) incident

on a display surface in a vertical orientation.[4],[5] The actual hemispherical diffuse
reflectance measurement may be taken at lower illumination levels.
2) Directional illumination – The directional light source shall approximate CIE daylight

Illuminant D50.[4] Additional CIE daylight illuminants may also be used, depending on
the intended application. The use of an infrared-blocking filter is recommended to
minimize sample heating. The UV region (< 380 nm) of the light source shall be cut off.
If it can be demonstrated that the display does not exhibit significant PL for a source
approximating Illuminant D50, then a spectrally smooth broadband source (such as an
approximation to CIE Standard Illuminant A) may be used for the reflectance factor
measurement. The ambient contrast ratio or colour can be calculated later with the
D50 Illuminant spectra. The daylight contrast ratio or colour shall be calculated using
65 000 lx for a directed source at an inclination angle of θ = 45° to the display surface
s
(see Figure 3).[4],[5] The actual reflectance factor measurement may be taken at lower
illumination levels, and the contrast ratio and colour calculated for the correct
illuminance. The directed source shall have an angular subtense of approximately 0,5°.
For daylight contrast ratio and colour calculations from spectral reflectance factor
measurements, the relative spectral distributions of CIE Illuminants A, D65, D50 and
D75 tabulated in CIE 15:2004 shall be used. Additional CIE daylight illuminants shall
be determined using the appropriate eigenfunctions, as defined in CIE 15:2004.
5.2.2.3 Uniform hemispherical diffuse illumination
An integrating sphere, sampling sphere, or hemisphere shall be used to implement uniform
hemispherical illumination conditions. Two possible examples of the measurement geometry
are shown in Figure 2. If an integrating sphere that is at least seven times the physical outer
diagonal of the display is available, the display can be mounted in the centre of the sphere
(Figure 2, configuration A). For large displays, a sampling sphere (configuration B) or
hemisphere would be more suitable. In all cases, the configuration shall follow the standard
di/8° to di/10° illumination/detection geometry, where di is the standard notation for diffuse
with specular included.
Specular
Light
Measurement port
point
source
Baffle
θ = 8° to 10°
Display
θθ θθ
LamLampp
Reflectance
standard
8° to 10°
BBaaffffllee
Sample port
Light
measuring
DDisisplaplay y
device
IEC
IEC
Configuration A (top view) Configuration B (side view)
Figure 2 –Example of measurement geometries for a uniform hemispherical
diffuse illumination condition using an integrating sphere and sampling sphere
1) The display is placed in the centre of an integrating sphere/hemisphere, or against the
sample port of a sampling sphere. The reflected luminance off the display from the sphere
shall be much greater (> 10) than the luminance from the display-generated light. For
displays without significant PL, the reflected luminance from the sphere can be estimated
with the display turned OFF.
2) For daylight measurements with an approximate 7 500 K CCT light source, an infrared-
blocking filter is recommended to minimize sample heating. The colour temperature and
illumination spectra can be measured from the reflected light of a white diffuse reflectance
standard near the display measurement area (Figure 2, configuration A), or the sampling

– 14 – IEC 62341-6-2:2015 © IEC 2015
sphere wall adjacent to the sample port (Figure 2, configuration B). The type of light
source used, and its CCT, shall be noted in the ambient performance report.
3) The LMD is aligned to view the centre of the display through a measurement port in the
+2
sphere wall at an 8° angle from the display normal. The required LMD angle of
inclination can also be realised by tilting the display within the integrating sphere. The
LMD is focused on the display surface.
4) The measurement port diameter shall be 20 % to 30 % larger than the effective aperture
of the LMD lens. Care needs to be taken to avoid any direct light from the sources, or any
bright reflections off any surface (other than the screen itself), from hitting the lens of the
LMD in order to minimise veiling glare contamination of the reflected luminance
measurement. The LMD shall be moved back from the hole so that the bright walls of the
sphere are not visible to the LMD. In addition, the sample port diameter will typically need
to be larger than 25 mm in order for the luminance meter’s or spectroradiometer’s field of
view to be completely contained within the sample port.
5) The measurement port shall be bevelled away from the lens. The small diameter of the
bevel is toward the LMD, and the large diameter on the inside of the sphere.
6) The spectral irradiance or illuminance on the display can be measured using a white
diffuse reflectance standard with known hemispherical diffuse spectral reflectance factor
ρ (λ), or the photopically-weighted (or luminous) hemispherical diffuse reflectance factor
std
ρ . The white diffuse reflectance standard shall be calibrated under uniform
std
hemispherical diffuse illumination in an integrating sphere. When an integrating sphere
(configuration A) or hemisphere is used, the white diffuse reflectance standard shall be
placed on the display surface. If t is the thickness of the white diffuse reflectance standard,
then it shall be placed on the surface at a distance of 5 × t to 7 × t from the measurement
area. The white reflectance standard can also be placed adjacent to and in the same
plane as the display if the sphere illumination is uniform over that distance. In the case of
the sampling sphere, the spectral irradiance can be determined by a measurement of the
interior sphere wall adjacent to the sample port.[6] The hemispherical diffuse spectral
reflectance, or the luminous hemispherical diffuse reflectance, of the interior sphere wall
can be determined by comparing the spectral radiance (or luminance) of the wall with that
of a calibrated white diffuse reflectance standard placed at the sample port (i.e. ρ = ρ
wall std
× (L /L )).
wall std
7) If a sampling sphere is used, the display measurement area shall contain more than 500
display pixels. It is recommended that the sampling sphere be at least three times larger
than the sample port diameter. If there is a significant distance between the display
emitting surface and the sample port entrance, then the size of the sample port may need
to be increased.[7]
8) The illuminance across the display measurement area shall vary less than ±5 % from the
average.
5.2.2.4 Directed source illumination
Directional illumination shall be simulated by an isolated directed source (Figure 3) at a
defined angle of inclination to the display surface normal, or ring light (Figure 4) centred about
the normal. This measurement shall be performed in a dark room, with all potential reflective
room surfaces having a matt black coating. Light from the isolated directed source that is
reflected off the display in the specular direction can be collected by a light trap to minimize
its contribution to stray light contamination. The isolated directed source is the preferred
directed source. If the display exhibits strong asymmetric scatter (matrix scatter [8]), then a
ring light shall be used.
1) Position the LMD normal (θ = 0°) to the display, and focus on the display surface. The
d
isolated directed light source is aligned in the same vertical plane (φ = 90°) as the display
s
normal and LMD, but at an inclination angle θ from the horizontal plane. The distance
s
between the display and directe
...