Laser displays - Part 5-1: Measurement of optical performance for laser front projection

IEC 62906-5-1:2021(E) specifies the standard measurement conditions and measurement methods for front projection displays without screen which use lasers or laser hybrids as light sources. The hybrid light sources can use both lasers and spontaneous emission-based light sources. This document covers optical performance measurements for full-frame projection technologies such as digital micro mirror devices (DMDs), liquid crystal on silicon (LCOS), and liquid crystal display (LCD) projectors. Other displays, such as raster-scanned (flying spot) projection displays, are not included.

General Information

Status
Published
Publication Date
09-Nov-2021
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
10-Nov-2021
Ref Project

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IEC 62906-5-1
Edition 1.0 2021-11
INTERNATIONAL
STANDARD
colour
inside
Laser displays –
Part 5-1: Measurement of optical performance for laser front projection
IEC 62906-5-1:2021-11(en)
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---------------------- Page: 2 ----------------------
IEC 62906-5-1
Edition 1.0 2021-11
INTERNATIONAL
STANDARD
colour
inside
Laser displays –
Part 5-1: Measurement of optical performance for laser front projection
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.260 ISBN 978-2-8322-1049-5

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC 62906-5-1:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 5

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms, definitions and abbreviated terms ........................................................................ 7

3.1 Terms and definitions .............................................................................................. 7

3.2 Abbreviated terms ................................................................................................... 8

4 Standard measuring conditions ........................................................................................ 8

4.1 General ................................................................................................................... 8

4.2 Standard measuring environmental conditions ........................................................ 9

4.3 Standard dark room conditions................................................................................ 9

4.4 Standard conditions of measuring equipment .......................................................... 9

4.5 Conditions of measuring equipment ...................................................................... 10

4.5.1 General conditions ......................................................................................... 10

4.5.2 Measurement coordinate system ................................................................... 13

4.5.3 Diffuse reflectance standard .......................................................................... 13

4.5.4 Illuminance meter .......................................................................................... 14

4.5.5 Colorimeter .................................................................................................... 14

4.5.6 Signal source of test patterns ........................................................................ 14

4.5.7 Integrating sphere ......................................................................................... 14

4.5.8 Spectral radiance/irradiance meters............................................................... 15

5 Adjustment of the laser projector ................................................................................... 15

5.1 Projector and image plane placement ................................................................... 15

5.2 Focusing of the projector ...................................................................................... 15

5.3 Standard projector setup conditions ...................................................................... 16

5.4 Standard image measurement locations ................................................................ 16

5.5 Colour tile patterns ............................................................................................... 17

5.6 RGBCMY colour pattern ........................................................................................ 18

5.7 Measuring the projected image area ..................................................................... 19

5.8 Maintaining the normal working conditions ............................................................ 20

6 Measuring methods ....................................................................................................... 20

6.1 Light output ........................................................................................................... 20

6.2 Spectroradiometric measurements ........................................................................ 20

6.2.1 General ......................................................................................................... 20

6.2.2 Measuring equipment .................................................................................... 20

6.2.3 Measuring method ......................................................................................... 20

6.2.4 Data analysis ................................................................................................. 21

6.3 Illuminance uniformity ........................................................................................... 21

6.3.1 General ......................................................................................................... 21

6.3.2 Measuring equipment .................................................................................... 21

6.3.3 Measuring method ......................................................................................... 22

6.4 Contrast ratio ........................................................................................................ 22

6.4.1 General ......................................................................................................... 22

6.4.2 Measuring equipment .................................................................................... 22

6.4.3 Measuring method ......................................................................................... 22

6.5 Chromaticity coordinates ....................................................................................... 23

6.5.1 General ......................................................................................................... 23

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IEC 62906-5-1:2021 © IEC 2021 – 3 –

6.5.2 Measuring equipment .................................................................................... 23

6.5.3 Measuring method ......................................................................................... 23

6.5.4 Data analysis ................................................................................................. 24

6.6 White point chromaticity coordinates and correlated colour temperature ............... 24

6.6.1 General ......................................................................................................... 24

6.6.2 Measuring equipment .................................................................................... 24

6.6.3 Measuring method ......................................................................................... 25

6.6.4 Data calculation ............................................................................................. 25

6.7 Greyscale illuminance and chromaticity coordinates ............................................. 25

6.7.1 General ......................................................................................................... 25

6.7.2 Measuring equipment .................................................................................... 25

6.7.3 Measuring method ......................................................................................... 25

6.8 Colour uniformity .................................................................................................. 26

6.8.1 General ......................................................................................................... 26

6.8.2 Measuring equipment .................................................................................... 26

6.8.3 Measuring method ......................................................................................... 26

6.8.4 Data analysis ................................................................................................. 27

6.9 Colour gamut ........................................................................................................ 27

6.9.1 General ......................................................................................................... 27

6.9.2 Chromaticity gamut area ................................................................................ 28

6.9.3 CIELAB gamut volume ................................................................................... 30

Annex A (normative) RGB boundary colours for CIELAB gamut volume measurements ....... 33

A.1 General ................................................................................................................. 33

A.2 Equally spaced 98 boundary colours on the RGB cube ......................................... 33

A.3 Recommended 602 boundary colours on the RGB cube ........................................ 36

Annex B (informative) Calculation method for CIELAB gamut volume................................... 51

B.1 Purpose ................................................................................................................ 51

B.2 Procedure for calculating the colour gamut volume ............................................... 51

B.3 Number of sampled colours .................................................................................. 52

B.4 RGB cube surface subdivision method for CIELAB gamut volume calculation ....... 52

B.4.1 General ......................................................................................................... 52

B.4.2 Assumption .................................................................................................... 52

B.4.3 Uniform RGB grid algorithm ........................................................................... 53

B.4.4 Software example execution .......................................................................... 55

Annex C (informative) Calculation method for chromaticity gamut area overlap .................... 63

C.1 Purpose ................................................................................................................ 63

C.2 Chromaticity gamut area overlap ........................................................................... 63

Annex D (informative) Light output ....................................................................................... 64

D.1 White light output (WLO) method .......................................................................... 64

D.1.1 Purpose ......................................................................................................... 64

D.1.2 Measuring equipment .................................................................................... 64

D.1.3 Measuring method ......................................................................................... 64

D.1.4 Data calculation ............................................................................................. 64

D.2 Colour-signal white (CSW) method ....................................................................... 65

D.2.1 Purpose ......................................................................................................... 65

D.2.2 Measuring equipment .................................................................................... 65

D.2.3 Measuring method ......................................................................................... 65

D.2.4 Data calculation ............................................................................................. 66

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– 4 – IEC 62906-5-1:2021 © IEC 2021

Bibliography .......................................................................................................................... 67

Figure 1 – Virtual screen setup with (a) the illuminance LMD or (b) reflectance

standard placed at the projector image plane for standard measurements ............................ 12

Figure 2 – Polar coordinate system used to describe the inclination and azimuthal

angle of the projector ............................................................................................................ 13

Figure 3 – Example image pattern with width H and height V used to focus the

projector ............................................................................................................................... 16

Figure 4 – Standard measuring locations on the projected image .......................................... 17

Figure 5 – Set of four colour tile test patterns used for projector characterization ................. 18

Figure 6 – Standard medium APL RGBCMY test pattern used for centre illuminance

and colour measurements with 25 % APL ............................................................................. 19

Figure 7 – Area of projected image ....................................................................................... 20

Figure 8 – Example representation of the chromaticity gamut area in the CIE 1931

chromaticity diagrams ........................................................................................................... 29

Figure 9 – Example of range in colours produced by a given display as represented by

the CIELAB colour space ...................................................................................................... 32

Figure B.1 – Analysis flowchart for calculating the CIELAB gamut volume ............................ 52

Figure B.2 – Example of tessellation using a 5 × 5 grid of surface colours on the RGB

cube ..................................................................................................................................... 54

Figure B.3 – Example of tessellation for the RGB cube using a 3 × 3 grid ............................. 56

Figure B.4 – Example of tessellation for the CIELAB gamut volume using a 3 × 3 grid .......... 57

Figure C.1 – Example of CIE 1931 chromaticity gamut area overlap between the

measured and reference colour gamut .................................................................................. 63

Table 1 – Recommended format for greyscale results ........................................................... 26

Table 2 – Example of colour uniformity analysis .................................................................... 27

Table 3 – Equivalent 8-bit RGB input signals used for colour gamut area

measurements ...................................................................................................................... 28

Table 4 – Example of report format for CIELAB gamut volume .............................................. 32

Table A.1 – Equally spaced 98 RGB boundary colours used for CIELAB gamut volume

measurements ...................................................................................................................... 33

Table A.2 – Recommended RGB boundary colours used for CIELAB colour gamut

volume measurements .......................................................................................................... 36

Table B.1 – Example data format used for CIELAB colour gamut volume

measurements ...................................................................................................................... 56

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IEC 62906-5-1:2021 © IEC 2021 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LASER DISPLAYS –
Part 5-1: Measurement of optical performance for laser front projection
FOREWORD

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IEC 62906-5-1 has been prepared by IEC technical committee 110: Electronic displays. It is an

International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
110/1351/FDIS 110/1367/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

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at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are

described in greater detail at www.iec.ch/standardsdev/publications.
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– 6 – IEC 62906-5-1:2021 © IEC 2021

A list of all parts in the IEC 62906 series, published under the general title Laser displays, can

be found on the IEC website.

Future documents in this series will carry the new general title as cited above. Titles of existing

documents in this series will be updated at the time of the next edition.

The committee has decided that the contents of this document will remain unchanged until the

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• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
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IEC 62906-5-1:2021 © IEC 2021 – 7 –
LASER DISPLAYS –
Part 5-1: Measurement of optical performance for laser front projection
1 Scope

This part of IEC 62906 specifies the standard measurement conditions and measurement

methods for front projection displays without screen which use lasers or laser hybrids as light

sources. The hybrid light sources can use both lasers and spontaneous emission-based light

sources. This document covers optical performance measurements for full-frame projection

technologies such as digital micro-mirror devices (DMDs), liquid crystal on silicon (LCOS), and

liquid crystal display (LCD) projectors. Other displays, such as raster-scanned (flying spot)

projection displays, are not included.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

shall constitute requirements of this document. For dated references, only the edition cited

applies. For undated references, the latest edition of the referenced document (including any

amendments) applies.

IEC 60825-1, Safety of laser products – Part 1: Equipment classification and requirements

IEC 61947-1:2002, Electronic projection – Measurement and documentation of key
performance criteria – Part 1: Fixed resolution projectors

IEC 62471-5, Photobiological safety of lamps and lamp systems- Part 5: Image projectors

IEC TR 62977-2-3, Electronic display devices – Part 2-3: Measurements of optical properties –

Multi-colour test patterns
ISO/CIE 11664-4, Colorimetry – Part 4: CIE 1976 L*a*b* colour space

ISO 15076-1:2010, Image technology colour management – Architecture, profile format and

data structure – Part 1: Based on ICC.1:2010
CIE 15, Colorimetry
CIE 168-2005, Criteria for the evaluation of extended-gamut colour encoding
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
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– 8 – IEC 62906-5-1:2021 © IEC 2021

NOTE Most definitions and units are in accordance with the naming methods used in ISO 11145 and IEC 62906-1-2

3.1.1
chromaticity difference

geometric distance Δu′v′ between two colours in the CIE 1976 u’v’ chromaticity diagram

3.1.2
white light output (WLO) method

method that estimates total luminous flux measured from the average of nine points for a full

white screen or for a sequence of white tiles that total the area of the full screen

3.1.3
colour-signal white (CSW) method

method that estimates total luminous flux from the sum of the input-referred red, green, and

blue tile sequence

Note 1 to entry: The area of all colour tiles totals the area of the full screen.

3.2 Abbreviated terms
APL average picture level
CAT chromatic adaptation transform
CCT correlated colour temperature
CGV colour gamut volume
CIE International Commission on Illumination
CIELAB CIE 1976 (L*a*b*) colour space
CSW colour signal white
CT colour tile
DMD digital micro-mirror device
DUT device under test
EOTF electro-optical transfer function
ISO International Organization for Standardization
LCD liquid crystal display
LCOS liquid crystal on silicon
LDD laser display device
LED light emitting diode
LMD light measuring device
RGB red, green, blue
RGBCMY red, green, blue, cyan, magenta, yellow
SDR standard dynamic range
sRGB standard RGB colour space as defined in IEC 61966-2-1
WLO white light output
4 Standard measuring conditions
4.1 General

Unless stated otherwise, the following standard measuring conditions shall be used. When

carrying out optical measurements of the laser projector, the measuring environment,

equipment, and methods shall comply with IEC 60825-1 and IEC 62471-5 for human safety.

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IEC 62906-5-1:2021 © IEC 2021 – 9 –
4.2 Standard measuring environmental conditions

All the tests and measurements shall be made under the following standard environmental

conditions:
– temperature: 25 ºC ± 3 ºC
– relative humidity: 25 % to 85 %
– pressure: 86 kPa to 106 kPa
If other conditions are used, they shall be noted in the report.
NOTE For temperature sensitive cases, 25 ºC ± 2 ºC is used.
4.3 Standard dark room conditions

The laser projectors are intended to be measured under dark room conditions. The illuminance

contribution from unwanted background illumination shall be less than 1 / 20 of the projector’s

lowest illuminance in a given test pattern. The room background illuminance can be estimated

by using a projection mask (see section 15.1.4 in [1] ). For the determination of the colorimetric

values, the background tri-stimuli shall be applied.

When it is not possible to achieve the background illuminance conditions, then background

subtraction by using the projection mask for the same test pattern shall be used in the

measurement. If the luminance measurement with a reflectance standard is applied to

determine the illuminance, the dimension of the projection mask has to take into account the

measurement area of the reflectance standard instead of the measurement area of the

illuminance meter.

In the case of direct illuminance measurement, a stray light elimination tube (see section 15.1.5

in [1]) can be used with the illuminance meters to minimize the contribution of the background

illumination. A stray light elimination tube is required if for a given test pattern, the background

illuminance measured with a projection mask is more than 67 % of the illuminance measured

on the same location in the test pattern without the projection mask.

It should be noted that the reflections from the mask, projector shell, LMD and their frames in

the front of the detection area can produce significant background illuminance, especially in the

case of a luminance measurement. It is recommended to absorb the direct projection beam by

applying light traps behind the virtual screen. Blackout curtains and black room surface (such

as walls, ceiling, floor, etc.) with a reflectance less than 3 % are valuable for reducing the

background illuminati
...

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