IEC TS 62715-5-2:2016

Flexible display devices - Part 5-2: Measuring methods of optical characteristics from the vantage point for curved displays

IEC TS 62715-5-2:2016(E) specifies the general rules and the details of optical measuring methods from a fixed point (the so-called vantage point) for curved emissive and transmissive type displays such as OLED and LCD in dark room conditions. This document focuses on concave shape large screen displays (non-portable) around a horizontal and/or vertical axis with fixed or variable curvature radius. The measuring method stipulated in this technical specification is applied to the curved display modules under the following states:
- vantage-point luminance variation by viewing angles
- vantage-point contrast ratio variation by viewing angles
- vantage-point chromaticity variation of white colour by viewing angles
- vantage-point colour gamut area variation by viewing angles
- vantage-point chromaticity variation of primary colours by viewing angles
- luminance uniformity and its uniformity variation by viewing angles
- chromaticity uniformity and its uniformity variation by viewing angles
- viewing angle of half-luminance
- viewing angle of half-contrast.

General Information

• Status: Published
• Publication Date: 25-Apr-2016
• ICS: 29.180 - Transformers. Reactors
• ICS: 31.120 - Electronic display devices
• Technical Committee: TC 110 - Electronic displays
• Drafting Committee: WG 8 - TC 110/WG 8
• Current Stage: PPUB - Publication issued
• Start Date: 15-Jul-2016
• Completion Date: 26-Apr-2016

Overview

IEC TS 62715-5-2:2016 is a technical specification from the IEC that defines standardized measuring methods of optical characteristics from a fixed vantage point for curved emissive and transmissive displays (for example curved OLED and curved LCD). The document targets concave large-screen (non‑portable) displays with fixed or variable curvature around a horizontal and/or vertical axis and describes measurement in controlled dark‑room conditions. Its purpose is to provide repeatable, comparable test procedures for evaluating how optical performance changes with viewing angle on curved screens.

Key Topics

• Scope and purpose: Vantage‑point measurement for concave curved displays (non‑portable) under dark room conditions.
• Standard measuring equipment: Guidance on required equipment such as video signal generators and non‑contact luminance/measuring devices (LMDs).
• Measuring conditions: Environmental, power supply, warm‑up time, and dark‑room requirements to ensure consistent results.
• Measuring geometry: Definitions for horizontal and vertical vantage points, measuring layouts (moving LMD vs rotating display), minimum curvature radius considerations, and screen visual angles.
• Measurement points and test patterns: Typical 9‑point measurement grids and white/colour box test patterns used for vantage‑point tests.
• Optical characteristics measured:
  • Luminance variation by viewing angle
  • Contrast ratio variation by viewing angle
  • Chromaticity variation (white and primaries) by viewing angle
  • Colour gamut area variation by viewing angle
  • Luminance and chromaticity uniformity and their variation with viewing angle
  • Half‑luminance and half‑contrast viewing angles
• Reporting requirements: Standardized ways to record and present measurement results for traceability and comparison.

Applications

• Display manufacturers - validate optical performance of curved TVs, monitors, and large concave signage during R&D and production verification.
• Test labs and metrology facilities - perform repeatable vantage‑point measurements for product qualification and performance benchmarking.
• Quality assurance and procurement - specify and verify contractual display performance (luminance uniformity, colour shift, viewing‑angle metrics).
• System integrators and installers - assess viewing‑angle performance for room layouts and audience placement.

Keywords: IEC TS 62715-5-2, curved display measurement, vantage-point measurement, curved OLED, curved LCD, luminance uniformity, chromaticity variation, viewing angle measurement, optical characteristics.

Related Standards

• Normative reference: IEC 62715-1-1 (Flexible display devices - Terminology and letter symbols).
• Other parts of the IEC 62715 series (Flexible display devices) cover complementary topics; consult the IEC webstore for the current list of related documents.

Standards Content (Sample)

IEC TS 62715-5-2 ®
Edition 1.0 2016-04
TECHNICAL
SPECIFICATION
colour
inside
Flexible display devices –
Part 5-2: Measuring methods of optical characteristics from the vantage point
for curved displays
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IEC TS 62715-5-2 ®
Edition 1.0 2016-04
TECHNICAL
SPECIFICATION
colour
inside
Flexible display devices –
Part 5-2: Measuring methods of optical characteristics from the vantage point

for curved displays
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120 ISBN 978-2-8322-3300-9

– 2 – IEC TS 62715-5-2:2016 © IEC 2016
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references. 6
3 Terms, definitions and abbreviations . 6
3.1 Terms and definitions . 6
3.2 Abbreviations . 8
4 Standard measuring equipment . 8
4.1 Video signal generator . 8
4.2 Non-contact LMD . 8
5 Standard measuring conditions . 9
5.1 Standard measuring environmental conditions . 9
5.2 Power supply . 9
5.3 Warm-up time . 9
5.4 Standard measuring dark room conditions . 9
5.5 Adjustment of display modules . 9
5.6 Measuring geometry for vantage point . 10
5.6.1 General . 10
5.6.2 Measuring geometry in horizontal vantage point . 10
5.6.3 Measuring geometry in vertical vantage point . 10
5.7 Measuring layout for viewing position . 11
5.7.1 General . 11
5.7.2 Measuring layout by moving LMD . 11
5.7.3 Measuring layout by rotating the display module . 12
5.8 Minimum curvature radius for the measurement . 13
5.9 Screen visual angle . 14
5.9.1 Screen visual angle of a flat display module . 14
5.9.2 Screen visual angle of concave type display module . 14
6 Measuring methods of optical characteristics . 15
6.1 General . 15
6.1.1 Measuring items . 15
6.1.2 Measuring point locations . 15
6.1.3 Test pattern . 16
6.2 Measuring method . 17
6.2.1 Measuring method at the screen centre position . 17
6.2.2 Measuring method at viewing angle position . 18
6.3 Optical characteristics of white box by viewing angle . 18
6.3.1 Luminance variation by viewing angle . 18
6.3.2 Contrast ratio variation by viewing angle . 19
6.3.3 Chromaticity variation by viewing angle . 20
6.4 Optical characteristics of colour box by viewing angle . 20
6.4.1 Colour gamut area variation by viewing angle . 20
6.4.2 Chromaticity variation and ΔE by viewing angle . 21
6.5 Uniformity and uniformity variation . 22
6.5.1 General . 22
6.5.2 Luminance uniformity and uniformity variation by viewing angle . 23
6.5.3 Chromaticity uniformity and uniformity variation by viewing angle . 23

6.6 Half-luminance and half-contrast viewing angle . 23
6.6.1 Half-luminance viewing angle range . 23
6.6.2 Half-contrast viewing angle range . 24
7 Reporting . 24
7.1 Requirements of reporting . 24
7.2 Recommendations of measurement results reporting . 25
Bibliography . 30

Figure 1 – Measuring layout for non-contact measurement . 9
Figure 2 – Measuring geometry in horizontal vantage point (top view) . 10
Figure 3 – Measuring geometry in vertical vantage point (side view) . 11
Figure 4 – Measuring geometry by horizontal viewing angles (top view) . 12
Figure 5 – Measuring geometry by horizontal display directions (top view) . 13
Figure 6 – Minimum concave type curvature radius for the measurement (top view) . 14
Figure 7 – Screen visual angle of concave type display device (top view) . 15
Figure 8 – 9-point locations for vantage-point measurement . 16
Figure 9 – Nine white boxes for vantage-point measurement . 16
Figure 10 – Nine measuring points for vantage-point black measurement . 17
Figure 11 – Nine-colour boxes of R, G and B for vantage-point measurement . 17
Figure 12 – Measuring directions of 9 vantage points . 17
o o o o
Figure 13 – Measuring directions (right side) by viewing angle 0 , 15 , 30 and 45 . 18
Figure 14 – Measuring directions (right side) by viewing angle 0°, 15°, 30° and 45°
(front upper view). 18
Figure 15 – Measuring method for half-luminance viewing angle . 23

Table 1 – Example of measurement results for the optical characteristics. 26
Table 2 – Calculation results from the measurement data of Table 1 . 28

– 4 – IEC TS 62715-5-2:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FLEXIBLE DISPLAY DEVICES –
Part 5-2: Measuring methods of optical characteristics
from the vantage point for curved displays

FOREWORD
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Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62715-5-2, which is a technical specification, has been prepared by IEC technical
committee 110: Electronic display devices.

The text of this standard is based on the following documents:
Enquiry draft Report on voting
110/715/DTS 110/739/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62715 series, published under the general title Flexible display
devices, can be found on the IEC website.
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
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
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– 6 – IEC TS 62715-5-2:2016 © IEC 2016
FLEXIBLE DISPLAY DEVICES –
Part 5-2: Measuring methods of optical characteristics
from the vantage point for curved displays

1 Scope
This part of IEC 62715, which is a technical specification, specifies the general rules and the
details of optical measuring methods from a fixed point (the so-called vantage point) for
curved emissive and transmissive type displays such as OLED and LCD in dark room
conditions. This document focuses on concave shape large screen displays (non-portable)
around a horizontal and/or vertical axis with fixed or variable curvature radius.
The measuring method stipulated in this technical specification is applied to the curved
display modules under the following states:
• vantage-point luminance variation by viewing angles
• vantage-point contrast ratio variation by viewing angles
• vantage-point chromaticity variation of white colour by viewing angles
• vantage-point colour gamut area variation by viewing angles
• vantage-point chromaticity variation of primary colours by viewing angles
• luminance uniformity and its uniformity variation by viewing angles
• chromaticity uniformity and its uniformity variation by viewing angles
• viewing angle of half-luminance
• viewing angle of half-contrast
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 62715-1-1, Flexible display devices – Part 1-1: Terminology and letter symbols
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62715-1-1 as well
as the following apply.
3.1.1
curved display
display that has a single curvature radius along the screen horizontally and/or vertically
Note 1 to entry: The curvature radius of each screen position is fixed by the manufacturer or user controllable
curvature radius.
Note 2 to entry: The direction of curvature might be concave or convex from the viewer’s position.

Note 3 to entry: The curved screen display is also called curved display, as in curved TV and curved monitor.
3.1.2
vantage-point measurement
test configuration in which measurements are taken at various measuring points on the
display screen through a common observation point in space in front of the screen
Note 1 to entry: The observer (at the viewing distance D) is at a fixed point, the so-called vantage point or
viewing point, and then from that fixed vantage point, the angle of view from the screen centre to the corners is
changed according to human viewing directions toward the screen.
Note 2 to entry: In this document, the vantage point for the measurement is located on the same horizontal plane
as the display centre, and on a line between the display centre and the display’s axis of rotation.
3.1.3
screen visual angle
maximum range of vantage-point viewing directions Ɵ measured from the vantage point
VA
towards the edges of the display
Note 1 to entry: The horizontal screen visual angle is the range of vantage-point viewing directions between the
left and right edges of the screen.
Note 2 to entry: The vertical screen visual angle is the range of vantage-point viewing directions between the top
and bottom edges of the screen.
3.1.4
viewing angle
angle between the normal direction of the screen surface and the measurement or viewing
direction
Note 1 to entry: If there is no indication about the screen position, the viewing angle is based on the screen
centre.
Note 2 to entry: The horizontal viewing angle is the angle between the screen normal direction and the vantage
point, both lying on the same horizontal plane.
Note 3 to entry: The vertical viewing angle is the angle between the screen normal direction and the vantage
point, both lying on the same vertical plane.
3.1.5
luminance variation by viewing angle
percent difference of display white luminance, between normal incidence (at 0° viewing angle)
and a specific viewing angle at each screen measuring point or averaged over the screen
measuring points
3.1.6
contrast ratio variation by viewing angle
percent difference of contrast ratio between normal incidence (at 0° viewing angle) and a
specific viewing angle at each screen measuring point or averaged over the screen measuring
points
3.1.7
chromaticity variation by viewing angle
chromaticity difference between normal incidence (at 0° viewing angle) and a specific viewing
angle at each screen measuring point or averaged over the screen measuring points
3.1.8
luminance uniformity variation by viewing angle
percent difference of display white luminance uniformity between normal incidence (at 0°
viewing angle) and a specific viewing angle

– 8 – IEC TS 62715-5-2:2016 © IEC 2016
3.1.9
chromaticity uniformity variation by viewing angle
difference of chromaticity uniformity at normal incidence (at 0° viewing angle) to the other
viewing angle
3.1.10
half-luminance viewing angle
horizontal viewing angle that has the half value of the luminance at the normal direction
3.1.11
half-contrast viewing angle
horizontal viewing angle that has the half value of the contrast at the normal direction
3.2 Abbreviations
For the purposes of this document, the following abbreviations apply.
APL average picture level
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
LMD light measurement device
4 Standard measuring equipment
4.1 Video signal generator
An analogue video signal generator or a digital video signal generator is used. The signal
characteristics shall match with the measured curved display module. Input signal, in this
document, means pre-gamma signal and APL means post-gamma APL.
4.2 Non-contact LMD
For the purpose of vantage-point measurement, the non-contact LMD shall be used. When
using a non-contact LMD, a spectroradiometer or a non-contact colorimeter is installed, as
shown in Figure 1. The optical axis of the non-contact LMD should be normal in the case of
measuring the centre of the display surface. In this document, for the purpose of vantage-
from the LMD to the centre of the display
point measurement, the measuring distance l
M
screen shall be either the design viewing distance or 3V where V is the effective screen height
of the display and H is the horizontally effective screen width of the display. The design
viewing distance might be recommended based on the display resolution and curvature radius.
The LMD colour measurements shall comply with the colour matching functions for the CIE
1976 standard colorimetric observer.

Display module
V
LMD
Video
l
signal M
generator
Measuring distance
Control PC
(if used)
IEC
Figure 1 – Measuring layout for non-contact measurement
5 Standard measuring conditions
5.1 Standard measuring environmental conditions
Measurements shall be carried out under the standard environmental conditions. When
different environmental conditions are used, they shall be noted in the report.
Temperature: 25 °C ± 3 °C
Relative humidity: 25 % RH to 85 % RH
Atmospheric pressure: 86 kPa to 106 kPa
5.2 Power supply
The power supply for driving the DUT shall be adjusted to the rated voltage ±5 %. In addition,
the frequency of the power supply shall provide the rated frequency ±2 %.
5.3 Warm-up time
Measurements shall be started after the display modules and measuring instruments achieve
stability. Sufficient warm-up time is defined as the time elapsed from when the supply source
is switched on, and a 100 % gray level of input signal is applied to the DUT, until repeated
measurements of the display show a variation in luminance of no more than 2 % per minute
and 5 % per hour.
5.4 Standard measuring dark room conditions
The luminance contribution from the background illumination reflected off the test display
shall be ≤ 0,01 cd/m . If this condition is 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. The clothes of the observer(s) and the wall of the
room shall be dark in order to avoid the reflection of the light emitted from the display back
onto the display. The measurement for all measuring points of the display screen and all
measuring positions shall proceed in the same dark room.
5.5 Adjustment of display modules
Luminance, contrast and chromaticity of the white field and other relevant parameters of the
displays have to be adjusted to nominal status in the detail specification and they shall be
noted in the measurement report. When there is no level specified, the maximum contrast

– 10 – IEC TS 62715-5-2:2016 © IEC 2016
and/or luminance level shall be used. These adjustments shall be held constant for all
measurements, unless noted otherwise in the measurement report. Additional conditions are
specified separately for each measuring method.
5.6 Measuring geometry for vantage point
5.6.1 General
To measure in vantage-point directions, the display module should be installed on a rotatable
and tiltable fixture to enable the changes in horizontal, vertical, and/or oblique measuring
directions. In 5.6, it is assumed that the display module shall be generally installed in the
vertical position to the ground. The curvature type of the examples is concave, but the convex
type is also available for these applications. The measuring direction that is the same as the
viewing direction is varied according to each vantage point and each viewing angle of the
measuring position.
5.6.2 Measuring geometry in horizontal vantage point
Figure 2 shows the measuring geometry of the top view in the horizontal vantage point. The
measuring distance l at the left or right measuring point of the screen may be unequal to
M
that of the screen centre, which will require the LMD to be refocused at these points. The
measuring distance is based on the standard viewing distance of the normal direction. It can
be measured between the screen centre of the display module and the optical lens of the LMD.
Curved display module
Measuring point
LMD
l = 3V
M
H
Rotation
l < 0,1l
D M
Standard (normal)
Screen centre
viewing direction
IEC
Figure 2 – Measuring geometry in horizontal vantage point (top view)
5.6.3 Measuring geometry in vertical vantage point
Figure 3 shows the measuring geometry of the top view in the vertical vantage point. The
measuring distance l at the upper or lower measuring point of the screen may be unequal to
M
that of the screen centre, which will require the LMD to be refocused at these points. When
using a tripod mount for the LMD, the LMD might be rotated by the mount point. Because of
the gap l between the LMD lens and the mount point, the viewing angle of the upper/lower
D
and left/right measuring point of the screen becomes slightly small, but if l < 0,1 l , it can be
D M
neglected.
Curved display module
Measuring point
LMD
l = 3V
M
V
Tilt
Screen centre Standard (normal)
l < 0,1l
viewing direction D M
IEC
Figure 3 – Measuring geometry in vertical vantage point (side view)
5.7 Measuring layout for viewing position
5.7.1 General
When watching a display, according to the viewing position, a viewing angle shall be set up
between the display’s perpendicular direction and the viewing direction. In 5.7, for the
measurement by the viewing angle with the actual watching conditions of customers, the
range of the viewing position of normal to ±45° of the display which is possible in the actual
usage shall be applied. The range of the viewing angle might be determined from over 90
...