IEC 62595-1-2:2016
(Main)Display lighting unit - Part 1-2: Terminology and letter symbols
Display lighting unit - Part 1-2: Terminology and letter symbols
IEC 62595-1-2:2016(E) gives the preferred terms, their definitions and symbols for display lighting units (DLUs) such as backlight units (BLUs) of transmissive and transflective LCDs, and frontlight units (FLUs) of reflective LCDs and electronic paper (E-paper) displays, with the object of using the same terminology when publications are prepared in different countries. This edition includes the following significant technical changes with respect to the previous edition:
a) change in the series title in order to handle frontlight units;
b) new terms are added considering recent advances in display lighting unit (DLU) technology;
c) some of terms and definitions are corrected and revised, particularly to be consistent with IEC 62595-2;
d) some of the terms and definitions are corrected and revised, particularly to be consistent with IEC 60050 policy;
e) clause structure is rectified for categorizing terms correctly;
f) some of figures in Annex A are added or revised for better understanding.
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IEC 62595-1-2 ®
Edition 2.0 2016-02
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 1-2: Terminology and letter symbols
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IEC 62595-1-2 ®
Edition 2.0 2016-02
INTERNATIONAL
STANDARD
colour
inside
Display lighting unit –
Part 1-2: Terminology and letter symbols
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-3170-8
– 2 – IEC 62595-1-2:2016 IEC 2016
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references. 5
3 Terms and definitions . 5
3.1 Classification of terms . 5
3.2 Fundamental terms . 5
3.3 Terms related to passive optical components . 9
3.4 Terms related to solid-state light sources . 13
3.4.1 Light-emitting diode (LED) . 13
3.4.2 LED light bar . 14
3.5 Terms related to frontlight units . 15
3.6 Terms related to performances and specifications . 16
3.7 Terms related to backlight dimming . 18
4 Letter symbols (quantity symbols / unit symbols) . 20
Annex A (informative) Supplementary figures . 21
Figure A.1 – Backlighting concept for transmissive and transflective LCDs . 21
Figure A.2 – Examples of edge-lit backlight units . 21
Figure A.3 – Example of a direct-lit backlight unit . 22
Figure A.4 – Visual definition of the terms related to passive optical components such
as bezel and case . 22
Figure A.5 – Luminance uniformity on a backlight unit . 23
Figure A.6 – Polar coordinate system for evaluation of the angular luminance
distribution. 23
Figure A.7 – Angular luminance on a backlight unit . 24
Figure A.8 – Examples of spectral power distribution of a display lighting unit . 24
Figure A.9 – Incoherent light spread function for evaluation of optical characteristics of
a block in a block-wise dynamic backlight unit . 24
Figure A.10 – Light spread functions of three BLUs with different optical structures . 25
Figure A.11 – Checkerboard pattern for evaluation of the luminance uniformity
in a BLU . 26
Table 1 – Letter symbols (quantity symbols / unit symbols) . 20
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DISPLAY LIGHTING UNIT –
Part 1-2: Terminology and letter symbols
FOREWORD
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International Standard IEC 62595-1-2 has been prepared by IEC technical committee 110:
Electronic display devices.
This second edition cancels and replaces the first edition published in 2011. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) change in the series title in order to handle frontlight units;
b) new terms are added considering recent advances in display lighting unit (DLU)
technology;
c) some of terms and definitions are corrected and revised, particularly to be consistent with
IEC 62595-2;
d) some of the terms and definitions are corrected and revised, particularly to be consistent
with IEC 60050 policy;
– 4 – IEC 62595-1-2:2016 IEC 2016
e) clause structure is rectified for categorizing terms correctly;
f) some of figures in Annex A are added or revised for better understanding.
The text of this standard is based on the following documents:
FDIS Report on voting
110/720/FDIS 110/734/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 the parts in the IEC 62595 series, 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 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 (DLUs) such as backlight units (BLUs) of transmissive and transflective LCDs,
and frontlight units (FLUs) of reflective LCDs and electronic paper (E-paper) displays, with the
object of using the same terminology when publications are prepared in different countries.
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 60050-845, International Electrotechnical Vocabulary – Part 845: Lighting
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-845 as well
as the following apply.
3.1 Classification of terms
Terms for display lighting units (DLUs), such as backlight units (BLUs) and frontlight units
(FLUs) are classified as follows:
a) fundamental terms related to display lighting units (3.2);
b) terms related to passive optical components used in display lighting units (3.3);
c) terms related to solid-state light sources used in display lighting units (3.4);
d) terms related particularly to frontlight units (3.5);
e) terms related to performances and specifications (3.6);
f) terms related to backlight dimming (3.7).
The following definitions are applied for international standardization of the backlight units.
3.2 Fundamental terms
3.2.1
display lighting unit
DLU
lighting unit for recognition of the displayed images on a non-emissive electronic display
device
____________
Identical to CIE 17.4.
– 6 – IEC 62595-1-2:2016 IEC 2016
3.2.2
backlight unit
BLU
display lighting unit that is set at the rear of a non-emissive electronic display device such as
a transmissive or transflective liquid crystal (LC) device
Note 1 to entry: For an example, see Figure A.1.
3.2.3
edge-lit backlight unit
side-lit backlight unit
edge-light backlight unit
side-light backlight unit
backlight unit in which an optically transparent medium (typically light-guide plate) is used in
proximity with the light source(s) for introducing the light into the medium from one or several
sides of the medium to illuminate an LC device
Note 1 to entry: For an example, see Figure A.2.
3.2.4
direct-lit backlight unit
direct-view backlight unit
backlight unit in which a light chamber is used in combination with light source(s) that are
mounted inside the chamber, for illuminating a transmissive LC device mounted on the light
chamber for the purpose of image recognition
Note 1 to entry: For an example, see Figure A.3.
3.2.5
side-driven direct-lit backlight unit
backlight unit in which a light chamber is used in combination with light sources(s) that are
mounted on the inner sides of the light chamber for illuminating a panel mounted on the light
chamber for the purpose of image recognition
3.2.6
static backlight unit
single or integrated flat illumination system that operates with direct or alternative current and
possesses a unique optical characteristic
3.2.7
dynamic backlight unit
single or integrated illumination units that possess a unique electro-optical characteristic
which is synchronized with the local picture and its contents displayed on an LC device
3.2.8
blinking backlight unit
backlight unit that is periodically switched on and off for synchronically illuminating an LC
device
3.2.9
scanning backlight unit
backlight unit that is divided optically or spatially into several line blocks and is periodically
switched on and off, block by block, for synchronous illumination of an LC device
3.2.10
directional backlight unit
D-BLU
backlight unit that collimates emergent light into an arbitrary solid angle or directs the
collimated emergent light toward a spatial zone or surface on the back side of the LC device
3.2.11
multi-directional backlight unit
backlight unit in which the light sources (LEDs or LDs) are spatially mounted in an array
around a micro- or submicro-featured (structured) light-guide plate (LGP) or light-guide film
(LGF), for sequentially switching to create spatially and/or angularly directed light for
rendering a 3D image on the LC device
Note 1 to entry: LED and LD are defined later.
3.2.12
scanning directional backlight unit
scanning D-BLU
D-BLU that illuminates continuously or distinctively a wide solid angle and/or an area in front
of the backlight unit, i.e. the backside of the LC device, by consecutively switching (on and
off) the spatially distributed light source array on the side surfaces of the light-guide plate
(LGP)
3.2.13
spatio-temporal switching backlight unit
backlight unit that is divided optically or spatially into several horizontal blocks and
periodically switched on and off from top to bottom under a time table for illuminating or
flashing red, green, or blue light in synchronization with a field-sequential colour LC device
with or without micro colour filters
3.2.14
field alternate LCD backlight unit
top and bottom flashing
backlight unit that includes a single light-guide plate (single or spatially divided into top and
bottom) with distinctive upper and lower light source groups for illuminating an LC device in
which an image is divided into top and bottom parts that are displayed alternately on the LC
device in order to compensate the slow response time of the LC device
3.2.15
field alternate LCD backlight unit
left and right alternate flashing
backlight unit that includes a single light-guide plate (LGP) or stacked LGPs for illuminating
an LC device in which an image is divided into a left and right image in which the two images
are oriented in different directions and where the left and right images are displayed
alternately on the LC device in order to create a 3D image display
3.2.16
single-side light emission backlight unit
backlight unit that emits light from a front surface or rear surface (i.e. from a single side) for
illuminating a single LC device
3.2.17
double-sides light emission backlight unit
backlight unit that emits light from both the front and the rear surface for illuminating two LC
devices
3.2.18
segmented backlight unit
backlight unit that is divided into blocks or segments in two dimensions for synchronization
with an LC device for illuminating individually each block or segment of the LC device
3.2.19
quasi-monochromatic backlight unit
backlight unit that uses a single quasi-monochromatic light source for illuminating a
transmissive LC device
– 8 – IEC 62595-1-2:2016 IEC 2016
3.2.20
multi-colour backlight unit
backlight unit that consists of multiple primaries or multiple quasi-monochromatic light sources
for illuminating an LC device for displaying a wide colour gamut that is used for a printer,
professional design monitor or field alternative wide colour gamut LC device
3.2.21
portability enhanced backlight unit
backlight unit the optical components of which are thin and lightweight to enhance portability
3.2.22
corner driven backlight unit
edge-lit backlight unit in which the light is driven from one or several flattened corners of a
rectangular light-guide plate using single or multiple light sources
3.2.23
stack backlight unit
backlight unit in which more than one single light control medium or light-guide plate is used
in stack form in the structure for light direction controlling or light shaping
3.2.24
colour reproduction backlight unit
backlight unit that uses light sources of three or more primaries in order to produce a wide
colour gamut on an LC device
3.2.25
light-emitting diode backlight unit
LED backlight unit
backlight unit that uses LEDs as light sources
3.2.26
laser backlight unit
backlight unit that uses laser(s) as light source(s)
3.2.27
laser diode backlight unit
LD backlight unit
laser backlight unit that uses LD(s) as light source(s)
3.2.28
RG-white backlight unit
backlight unit that uses light sources such as LEDs or LDs that emit light of red, green and
white (i.e. RG-white) colours
3.2.29
RGW backlight unit
backlight unit that uses distinct red, green and pseudo-white LEDs or LDs as light sources
3.2.30
three primaries (R,G,B) backlight unit
backlight unit that uses three primary colours of red, green, and blue quasi-monochromatic
LEDs or monochromatic LDs as light sources
3.2.31
six primaries (R ,G ,B ,R ,G ,B ) backlight unit
1 1 1 2 2 2
backlight unit employing two groups of red, green and blue light sources for illuminating an LC
device which is used for reproduction of colours of photographs
3.2.32
single-flash backlight unit
backlight unit that flashes periodically and is synchronized with an LC device for the purpose
of inserting a black or grey frame in order to enhance the moving image quality on the display
3.2.33
multi-flash backlight unit
spatially linear segmented backlight unit for scanning or field-sequential colour display that
flashes periodically and is synchronized with the LC device for the purpose of inserting colour
fields (displayed image with single colour) or black or grey fields in order to enhance the
displayed image quality on the display or spatially mix the colours for displaying coloured
images
3.2.34
multi-primary colours backlight unit
backlight unit that employs multiple LEDs or LDs which have different peak wavelengths of
primaries
3.2.35
tandem backlight unit
backlight unit that is an integration of multiple distinct and overlapped edge-lit backlight units
3.2.36
quantum dot backlight unit
QD backlight unit
edge-lit or direct-lit backlight unit in which blue light source(s) such as LEDs or LDs stimulate
the film set on the backlight unit or a glass tube filled with quantum dot materials to create
white light with three primaries spectra on the backlight unit
3.3 Terms related to passive optical components
3.3.1
light-guide plate
LGP
optically transparent medium with thick and solid structure that is generally employed in an
edge-lit backlight unit for forming the required light distribution spatially for transmissive or
transflective LC devices
Note 1 to entry: For an example, see Figure A.4.
3.3.2
light-guide film
LGF
optically transparent medium with thin and flexible structure that is employed instead of light-
guide plate (LGP) in an edge-lit backlight unit for forming the required light distribution
spatially for a transmissive or transflective LC device
3.3.3
functional light-guide plate
functional light-guide film
optically transparent medium characterized by optical micro- or submicro-structures for
shaping spatially or angularly the required light distribution in an edge-lit backlight unit for
illuminating a transmissive or transflective LC device
3.3.4
slab light-guide plate
slab light-guide film
light-guide plate or light-guide film that has a slab geometrical shape
– 10 – IEC 62595-1-2:2016 IEC 2016
3.3.5
wedge light-guide plate
wedge light-guide film
light-guide plate or light-guide film with a wedge shape (single or double wedge) introducing
the light from the thicker side
3.3.6
inverted wedge light-guide plate
inverted wedge light-guide film
light-guide plate or light-guide film with a single or double wedge in which the light is
introduced from the thinner side
3.3.7
double-side functional light-guide plate
double-side functional light-guide film
light-guide plate or light-guide film structured with micro- or submicro-structure(s) on the rear
and front surfaces for light shaping on the backlight unit
3.3.8
single-side functional light-guide plate
single-side functional light-guide film
light-guide plate or light-guide film structured with light reflecting micro-reflectors or light
deflecting micro-deflectors arrays on the rear or front surface for shaping and extracting the
propagating light
3.3.9
diffusing light-guide plate
diffusing light-guide film
light-guide plate or light-guide film structured with light diffusing micro-structures on its rear
and front or both surfaces for light shaping or the resin of which is filled with diffusing
materials such as beads
3.3.10
reflective light-guide plate
reflective light-guide film
light-guide plate or light-guide film structured with optical micro-reflectors on the rear surface
for extracting light from the front surface
3.3.11
deflective light-guide plate
deflective light-guide film
light-guide plate or light-guide film structured with optical micro-deflective elements on the
front surface fo
...
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