IEC 62595-2-1:2016

IEC 62595-2-1 ®
Edition 1.0 2016-04
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 2-1: Electro-optical measuring methods of LED backlight unit

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IEC 62595-2-1 ®
Edition 1.0 2016-04
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 2-1: Electro-optical measuring methods of LED backlight unit

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-3299-6

– 2 – IEC 62595-2-1:2016 © IEC 2016
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references. 5
3 Terms, definitions and abbreviations . 5
3.1 Terms and definitions . 5
3.2 Abbreviations . 5
4 General measurement conditions . 5
4.1 Standard atmospheric conditions for LED BLU . 5
4.2 Measuring setup . 6
4.3 Warm-up time . 6
5 Measurement methods . 7
5.1 Electrical measurement methods . 7
5.1.1 Conditions . 7
5.1.2 Current . 7
5.1.3 Voltage . 7
5.1.4 Power consumption . 7
5.2 Optical measurement methods . 7
5.2.1 Conditions . 7
5.2.2 Luminance . 8
5.2.3 Luminance uniformity or non-uniformity . 9
5.2.4 Spectral power distribution . 10
5.2.5 Chromaticity. 10
5.2.6 Colour uniformity . 10
5.2.7 Angular luminance uniformity . 11
5.2.8 Angular colour uniformity . 11
5.2.9 Measurement methods of block-wise BLUs . 11
Bibliography . 16

Figure 1 – Example of measuring setup for LED BLU . 6
Figure 2 – Example of warm-up characteristic of BLU . 7
Figure 3 – Definition of zenith angle θ and azimuth angle ϕ . 8
Figure 4 – Examples of measurement point layout . 10
Figure 5 – Angular luminance uniformity measurement . 11
Figure 6 – Example of checkerboard pattern (8 segments × 10 segments) for block-
wise BLU . 12
Figure 7 – Example of single block white pattern . 12
Figure 8 – Example of single block black pattern . 13
Figure 9 – Example of incoherent point spread function . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DISPLAY LIGHTING UNIT –
Part 2-1: Electro-optical measuring methods
of LED backlight 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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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 62595-2-1 has been prepared by IEC Technical Committee 110:
Electronic display devices.
This first edition cancels and replaces the first edition of IEC 62595-2 published in 2012. This
edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) changed the series title in order to cover frontlight unit;
b) added the detailed measurement procedures particularly for block-wise BLU;
c) deleted Annex A;
d) revised Figure 1 and Figure 2 and some editorial errors.

– 4 – IEC 62595-2-1:2016 © IEC 2016
The text of this standard is based on the following documents:
FDIS Report on voting
110/731A/FDIS 110/743A/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 62595 series, published under the general title Display lighting
unit, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
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.
DISPLAY LIGHTING UNIT –
Part 2-1: Electro-optical measuring methods
of LED backlight unit
1 Scope
This part of IEC 62595 specifies the standard measurement conditions and measuring
methods for determining the electrical and optical parameters of LED backlight units for liquid
crystal displays.
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 61747-30-1, Liquid crystal display devices – Part 30-1: Measuring methods for liquid
crystal display modules – Transmissive type
IEC 62595-1-2, Display lighting unit – Part 1-2: 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 62595-1-2 apply.
3.2 Abbreviations
BLU backlight unit
FOV field of view
LMD light measuring device
LSF light spread function
4 General measurement conditions
4.1 Standard atmospheric conditions for LED BLU
Unless otherwise specified, all tests and measurements for LED BLU shall be carried out after
sufficient warm-up time (see 4.3), under the standard environmental conditions, at a
temperature of 25 °C ± 3 °C, a relative humidity of 25 % to 85 %, and an atmospheric
pressure of 86 kPa to 106 kPa. When different environmental conditions are used, they shall
be noted in the detail specification (see IEC 61747-30-1).
______________
To be published.
– 6 – IEC 62595-2-1:2016 © IEC 2016
4.2 Measuring setup
Figure 1 shows a typical setup of a BLU, luminance meter, power source, block controller,
voltmeters and current meters for electro-optical measurements for LED BLU.
LMD
(Luminance meter)
Block control
Power supply
signal
(for block-wise BLU)
FOV
BLU
Sample stage
I
Block control Ammeter
Power supply
signal
(for block-wise BLU)
Voltmeter
V
I
BLU
I
V
I V
BLU
signal
BLU
I
V V
signal
IEC
Figure 1 – Example of measuring setup for LED BLU
4.3 Warm-up time
The luminance of LED backlights is affected by the transient temperature behaviour of LED
output as in Figure 2. It takes a certain time for LEDs until their junction temperature reaches
the steady state. Luminance measurement shall be carried out and recorded until the
fluctuations of luminance measured at an appropriate point (usually at the centre point) of the
BLU become less than the range specified in IEC 61747-30-1 unless otherwise specified. The
luminance measurement shall be carried out as in 5.2.2. All measuring conditions shall be
kept constant during the measurements.
Chromaticity measurement shall be carried out in the same manner as in the above, unless
otherwise specified. The chromaticity measurement shall be carried out as in 5.2.5.
The above measurements can be customized between the customer and the supplier,
depending on various BLU sizes, applications, and so on.
Measurement
distance
1,4
1,2
1,0
0,8
0,6
0,4
0,2
0,0
0 10 20 30 40 50 60
Time (min)
IEC
Figure 2 – Example of warm-up characteristic of BLU
5 Measurement methods
5.1 Electrical measurement methods
5.1.1 Conditions
The BLU shall be placed in the measurement arrangement and it shall be assured that all
required conditions are fulfilled.
After applying the initial electrical driving conditions (i.e. analogue input voltage(s) or digital
input signals) of the BLU and waiting during the warm-up time specified in 4.3 in ord
...