Electronic displays - Part 1-31: Generic - Practical information for use of light measuring devices

IEC TR 62977-1-31:2021(E) provides practical information on light measuring devices (luminance meters, colorimeters, and spectroradiometers) with luminance measuring optics for the characterization of electronic displays.

General Information

Status
Published
Publication Date
25-Apr-2021
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
26-Apr-2021
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IEC TR 62977-1-31
Edition 1.0 2021-04
TECHNICAL
REPORT
colour
inside
Electronic displays –
Part 1-31: Generic – Practical information on the use of light measuring devices
IEC TR 62977-1-31:2021-04(en)
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IEC TR 62977-1-31
Edition 1.0 2021-04
TECHNICAL
REPORT
colour
inside
Electronic displays –
Part 1-31: Generic – Practical information on the use of light measuring devices
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120; 31.260 ISBN 978-2-8322-9716-2

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 62977-1-31:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 6

INTRODUCTION ..................................................................................................................... 8

1 Scope .............................................................................................................................. 9

2 Normative references ...................................................................................................... 9

3 Terms, definitions, and abbreviated terms ....................................................................... 9

3.1 Terms and definitions .............................................................................................. 9

3.2 Abbreviated terms ................................................................................................. 10

4 General information on LMDs for photometry and colorimetry ........................................ 10

4.1 General ................................................................................................................. 10

4.2 Photometry and colorimetry for electronic displays ................................................ 10

4.3 LMDs for luminance and chromaticity measurements ............................................ 11

4.3.1 Configuration of LMDs ................................................................................... 11

4.3.2 Input optics of LMDs ...................................................................................... 13

4.3.3 Electronic system of LMDs ............................................................................ 13

4.3.4 Calibration of LMDs ....................................................................................... 14

4.3.5 Maintenance of LMDs .................................................................................... 14

4.4 Setup conditions for measurement ........................................................................ 14

4.4.1 LMDs ............................................................................................................. 14

4.4.2 DUTs ............................................................................................................. 14

4.4.3 Environment .................................................................................................. 14

5 Influence of LMD properties on luminance and chromaticity measurements ................... 14

5.1 General ................................................................................................................. 14

5.2 Repeatability ......................................................................................................... 15

5.2.1 General ......................................................................................................... 15

5.2.2 Example of the repeatability of an LMD.......................................................... 15

5.3 Accuracy ............................................................................................................... 16

5.3.1 General ......................................................................................................... 16

5.3.2 Example of the accuracy of an LMD ............................................................... 16

5.3.3 Linearity ........................................................................................................ 16

5.3.4 Range change ............................................................................................... 17

5.4 Luminance range .................................................................................................. 17

5.5 Spectral properties of the spectroradiometer ......................................................... 17

5.5.1 General ......................................................................................................... 17

5.5.2 Wavelength accuracy and spectral bandwidth ................................................ 17

5.6 Spectral properties of the filter-type luminance meter and colorimeter .................. 23

5.6.1 General ......................................................................................................... 23

5.6.2 Spectral responsivity ..................................................................................... 23

5.6.3 Methods to reduce the measurement difference ............................................. 25

5.7 Angular response of LMDs .................................................................................... 26

5.7.1 General ......................................................................................................... 26

5.7.2 Subtended angles .......................................................................................... 26

5.7.3 Consideration of the input optics .................................................................... 27

5.8 Measurement field ................................................................................................ 28

5.8.1 General ......................................................................................................... 28

5.8.2 Number of pixels within the measurement field .............................................. 29

5.9 Polarization ........................................................................................................... 29

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IEC TR 62977-1-31:2021 © IEC 2021 – 3 –

5.9.1 General ......................................................................................................... 29

5.9.2 Polarization dependence of LMDs.................................................................. 30

5.10 Temporal synchronization ..................................................................................... 31

5.10.1 General ......................................................................................................... 31

5.10.2 Temporal synchronization of the LMD and DUT ............................................. 31

6 Influence of LMD properties on measurements of the optical characteristics of

electronic displays ......................................................................................................... 32

6.1 General ................................................................................................................. 32

6.2 Contrast ratio ........................................................................................................ 32

6.2.1 General ......................................................................................................... 32

6.2.2 Calculated influence of LMD properties on the contrast ratio

measurements ............................................................................................... 32

6.3 Electro-optical transfer function (EOTF) ................................................................ 35

6.3.1 General ......................................................................................................... 35

6.3.2 Calculated influence of the LMD properties on the EOTF measurements ....... 35

6.4 Chromaticity gamut area ....................................................................................... 36

6.4.1 General ......................................................................................................... 36

6.4.2 Calculated influence of LMD properties on the chromaticity gamut area

measurements ............................................................................................... 36

6.5 Viewing direction characteristics ........................................................................... 38

6.5.1 General ......................................................................................................... 38

6.5.2 Calculated influence of the LMD properties on the viewing direction

characteristics measurements ....................................................................... 38

6.5.3 Measurement field at an oblique direction ...................................................... 40

6.6 Spatial uniformity .................................................................................................. 41

6.6.1 General ......................................................................................................... 41

6.6.2 Calculated influence of LMD properties on uniformity and non-uniformity

measurements ............................................................................................... 41

6.7 Response time ...................................................................................................... 43

6.7.1 General ......................................................................................................... 43

6.7.2 Measurement of the response time ................................................................ 43

6.8 Flicker ................................................................................................................... 46

6.8.1 General ......................................................................................................... 46

6.8.2 Measurement method of the flicker ................................................................ 46

6.8.3 Low-pass filter of LMDs ................................................................................. 47

Annex A (informative) Photometry and colorimetry ............................................................... 49

A.1 General ................................................................................................................. 49

A.2 Photometry ........................................................................................................... 49

A.3 Colorimetry ........................................................................................................... 49

A.3.1 General ......................................................................................................... 49

A.3.2 Standard colorimetric observer ...................................................................... 50

A.3.3 Tristimulus values .......................................................................................... 50

A.3.4 Chromaticity diagram and colour space ......................................................... 50

Annex B (informative) Method for reducing the measurement difference of

colorimeters .......................................................................................................................... 53

B.1 General ................................................................................................................. 53

B.2 Matrix calibration methods for colorimeters ........................................................... 53

B.2.1 Matrix calibration process 1: RGB calibration ................................................. 53

B.2.2 Matrix calibration process 2: RGBW calibration ............................................. 54

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– 4 – IEC TR 62977-1-31:2021 © IEC 2021

Annex C (informative) Input data in Clause 5 and Clause 6, and calculation methods

in 5.8 and 6.5 ........................................................................................................................ 56

C.1 General ................................................................................................................. 56

C.2 Characteristics of DUTs ........................................................................................ 56

C.2.1 Spectral radiances of the DUTs ..................................................................... 56

C.2.2 Directional characteristic of the DUT .............................................................. 57

C.2.3 Temporal modulation characteristics of the DUT ............................................ 57

C.2.4 EOTF characteristics of the DUTs .................................................................. 57

C.2.5 Uniformity characteristics of the DUTs ........................................................... 58

C.3 Characteristics of the filter-type LMDs .................................................................. 59

C.3.1 Spectral responsivities of the filter-type LMDs ............................................... 59

C.3.2 Specifications of filter-type LMDs ................................................................... 61

C.4 Influence of the number of pixels within the measurement field ............................. 63

C.5 Validity of the viewing direction dependence obtained by a simplified method ....... 64

Annex D (informative) Instabilities of DUTs in measurement ................................................ 66

D.1 General ................................................................................................................. 66

D.2 DUT instabilities .................................................................................................... 66

Bibliography .......................................................................................................................... 68

Figure 1 – Block diagrams of three types of LMDs ................................................................ 12

Figure 2 – Example of configurations for the input optics and detector .................................. 12

Figure 3 – Example of input optics for the luminance meters ................................................. 13

Figure 4 – Block diagram of a typical electronic system ........................................................ 13

Figure 5 – Examples of the repeatability of an LMD as a function of luminance ..................... 15

Figure 6 – Examples of the accuracy of an LMD as a function of luminance .......................... 16

Figure 7 – Calculated relative luminance difference as a function of wavelength error .......... 19

Figure 8 – Calculated relative luminance difference as a function of spectral bandwidth ....... 20

Figure 9 – Calculated chromaticity differences as a function of wavelength error .................. 21

Figure 10 – Calculated chromaticity differences as a function of spectral bandwidth ............. 22

Figure 11 – Calculated relative luminance difference as a function of f ............................... 24

Figure 12 – Calculated chromaticity differences as a function of f ............................... 25

1 , xyz

Figure 13 – Angular aperture and measurement field angle .................................................. 27

Figure 14 – Calculated relative luminance difference and chromaticity difference as a

function of the angular aperture ............................................................................................ 27

Figure 15 – Diagram of light rays in object space telecentric and non-telecentric optical

design ................................................................................................................................... 28

Figure 16 – Calculated chromaticity difference as a function of the number of pixels ............ 29

Figure 17 – Measured luminance variation as a function of the rotation angle of the

polarizer ............................................................................................................................... 30

Figure 18 – Calculated relative luminance differences as a function of sampling period ........ 32

Figure 19 – Total measurement times for 0,3 % repeatability (2σ) in three LMDs .................. 36

Figure 20 – Calculated relative difference, ΔGA , by spectroradiometers ............................ 37

Figure 21 – Calculated relative difference, ΔGA , by colorimeters ....................................... 38

Figure 22 – Cone of light rays for calculating the tristimulus values measured by an

LMD with the angular aperture, α, and an optical axis at an inclination angle, θ ............. 39

LMD
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IEC TR 62977-1-31:2021 © IEC 2021 – 5 –

Figure 23 – Calculated luminance and chromaticity dependence as a function of the

inclination angle for the 2°, 6°, and 10° angular apertures ..................................................... 40

Figure 24 – Measurement field and test pattern .................................................................... 41

Figure 25 – Calculated non-uniformity difference by the filter-type colorimeters .................... 43

Figure 26 – Measurement setups for response time measurements ...................................... 44

Figure 27 – Response curves measured at different sampling rates ...................................... 44

Figure 28 – Measured response subjected to various low-pass filterings ............................... 45

Figure 29 – Measured response curves switched from the 10 % to 90 % level ...................... 46

Figure 30 – Schematic measured temporal luminance modulation of the LCD with a

common voltage offset .......................................................................................................... 47

Figure 31 – Conceptual pseudo-temporal luminance modulation ........................................... 48

Figure 32 – Simulated luminance modulations with and without high frequency noise ........... 48

Figure C.1 – Spectral radiances ............................................................................................ 56

Figure C.2 – Inclination angle dependence ........................................................................... 57

Figure C.3 – Temporal modulation of the luminance ............................................................. 57

Figure C.4 – EOTF characteristics ........................................................................................ 58

Figure C.5 – Spectral responsivity of the colorimeter ............................................................ 61

Figure C.6 – Repeatability of three LMD models ................................................................... 62

Figure C.7 – Three positions of a circular measurement field relative to the RGB

stripes .................................................................................................................................. 63

Figure C.8 – Configuration to measure DUT emission by the LMD at the inclination

angle, θ ......................................................................................................................... 64

LMD
Figure C.9 – Inclination angle dependence calculated by two methods using an LMD

with an angular aperture of 10° ............................................................................................. 65

Figure D.1 – Changes of luminance and chromaticity after switching the grey levels ............. 66

Figure D.2 – Changes of luminance after switching from the black to grey level .................... 67

Table 1 – DUT characteristics for the calculations ................................................................. 33

Table 2 – Calculated results of the contrast ratio by three LMDs ........................................... 34

Table 3 – Calculated durations of the EOTF measurements .................................................. 36

Table 4 – Chromaticity gamut area of three DUTs ................................................................. 37

Table 5 – Non-uniformity of DUTs ......................................................................................... 42

Table 6 – Rise times calculated from a measured response subjected to various low-

pass filterings ....................................................................................................................... 45

Table 7 – Rise times measured by LMDs of various V(λ) fidelities ......................................... 46

Table C.1 – Measured luminance and chromaticity at the nine positions of DUT-1 ................ 58

Table C.2 – Measured luminance and chromaticity at the nine positions of DUT-2 ................ 59

Table C.3 – Specifications of filter-type LMDs ....................................................................... 62

Table D.1 – Luminance and chromaticity transition ............................................................... 66

Table D.2 – Luminance changes in two measurements ......................................................... 67

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– 6 – IEC TR 62977-1-31:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRONIC DISPLAYS –
Part 1-31: Generic –
Practical information on the use of light measuring devices
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 international

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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) 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.

IEC TR 62977-1-31 has been prepared by IEC technical committee 110: Electronic displays. It

is a Technical Report.
The text of this Technical Report is based on the following documents:
DTR Report on voting
110/1258/DTR 110/1281A/RVDTR

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 Technical Report is English.
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IEC TR 62977-1-31:2021 © IEC 2021 – 7 –

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/standardsdev/publications.

A list of all parts in the IEC 62977 series, published under the general title Electronic displays,

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 "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• 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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of its contents. Users should therefore print this document using a colour printer.

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– 8 – IEC TR 62977-1-31:2021 © IEC 2021
INTRODUCTION

Measurements of the optical characteristics of electronic displays are primarily affected by three

factors: measuring procedures, displays (devices under test: DUTs), and light measuring

devices (LMDs), for which there are many international standards supporting consistent and

comparable measurements. Most of them, however, provide only limited information on LMDs,

making it difficult to appropriately select and use the LMD for the measurement objective. The

purpose of this document is to provide best practices and suggestions which are missing in the

standards.

This document addresses how the major properties of a typical LMD affect the measurement

results. It is often impractical and unnecessary to consider the influences of all properties of

LMDs and all characteristics of DUTs as well as their interactions and influences on the

measurement results. Therefore, the multiple inte
...

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