IEC 62595-1-2:2024
(Main)Display lighting unit - Part 1-2: Terminology and letter symbols
Display lighting unit - Part 1-2: Terminology and letter symbols
IEC 62595-1-2:2024 gives the preferred terms, their definitions and symbols, for display lighting units such as backlight units of transmissive and transflective displays, and frontlight units of reflective displays, with the objective of using standardized terminology when publications are prepared.
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IEC 62595-1-2 ®
Edition 3.0 2024-12
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 1-2: Terminology and letter symbols
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IEC 62595-1-2 ®
Edition 3.0 2024-12
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 1-2: Terminology and letter symbols
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8327-0094-5
– 2 – IEC 62595-1-2:2024 © IEC 2024
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
3.1 General . 5
3.2 Classification of terms . 5
3.3 Fundamental terms . 6
3.4 Terms related to passive optical components . 10
3.5 Terms related to spatio-temporally modulated BLUs . 14
3.6 Terms related to solid-state light sources . 15
3.7 Terms related to light shaping guide in frontlight unit . 18
3.8 Terms related to specifications . 19
3.9 Terms related to backlight dimming . 21
3.10 Terms related to photoluminescent materials . 22
3.11 Terms related to DLU luminance . 24
4 Letter symbols (quantity symbols/unit symbols) . 24
Annex A (informative) Supplementary figures. 26
Annex B (informative) Quantum dot film . 32
Annex C (informative) Backlight unit and Light guide plate structures . 34
Annex D (informative) Frontlight unit with a lightguide plate and a LED light source . 36
Bibliography . 37
Figure A.1 – Backlighting concept for transmissive and transflective LCDs . 26
Figure A.2 – Examples of edge-lit backlight units . 26
Figure A.3 – Example of a direct-lit backlight unit with LED light bars . 27
Figure A.4 – Visual definition of the terms related to passive optical components such
as bezel and case for an LCD . 27
Figure A.5 – Luminance uniformity on a backlight unit . 28
Figure A.6 – Spherical coordinate system for evaluation of the angular or directional
luminance distribution . 28
Figure A.7 – Light cone on an edge-lit backlight unit . 28
Figure A.8 – Examples of spectral power distribution of a display lighting unit . 29
Figure A.9 – Incoherent light spread function for evaluation of optical characteristics of
a block in a block-wise dynamic backlight unit . 29
Figure A.10 – Light spread functions of three BLUs with different optical structures . 30
Figure A.11 – Checkerboard pattern for evaluation of the luminance uniformity in a BLU . 31
Figure B.1 – Schematic diagram of an LCD with QD film used edge-lit BLU . 32
Figure B.2 – Schematic diagram of an LCD with QD-DP used direct-lit BLU . 33
Figure C.1 – A hollow type side-lit BLU . 34
Figure C.2 – A stack type edge-lit BLU . 34
Figure C.3 – Tandem type edge-lit BLU . 34
Figure C.4 – Cross section of a wedge shape light-guide plates . 35
Figure D.1 – Cross section of a frontlight unit (FLU) on an electronic paper . 36
Table 1 – Letter symbols (quantity symbols/unit symbols) . 25
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DISPLAY LIGHTING UNIT –
Part 1-2: Terminology and letter symbols
FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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IEC 62595-1-2 has been prepared by IEC technical committee 110: Electronic displays. It is an
International Standard.
This third edition cancels and replaces the second edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) new terms are added considering recent advances in display lighting unit (DLU) technology;
b) some of the terms and definitions are corrected and revised, particularly to be consistent
with IEC 60050 policy;
c) clause structure is updated for categorizing terms correctly;
– 4 – IEC 62595-1-2:2024 © IEC 2024
d) some of the figures in informative Annex A and their captions are revised for better
understanding;
e) an informative Annex B is added for pictorial definition of the backlight unit structure.
f) an informative Annex C is added for pictorial definition of the backlight unit varieties and
light-guide plate shapes.
The text of this International Standard is based on the following documents:
Draft Report on voting
110/1698/FDIS 110/1725/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
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.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document 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 1-2: Terminology and letter symbols
1 Scope
This part of IEC 62595 gives the preferred terms, their definitions and symbols, for display
lighting units such as backlight units of transmissive and transflective displays, and frontlight
units of reflective displays, wi
...
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