IEC 61747-40-2:2015

IEC 61747-40-2 ®
Edition 1.0 2015-01
INTERNATIONAL
STANDARD
Liquid crystal display devices –
Part 40-2: Mechanical testing of display cover glass for mobile devices – Uni-
axial flexural strength (4-point bend)
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IEC 61747-40-2 ®
Edition 1.0 2015-01
INTERNATIONAL
STANDARD
Liquid crystal display devices –

Part 40-2: Mechanical testing of display cover glass for mobile devices – Uni-

axial flexural strength (4-point bend)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 31.120 ISBN 978-2-8322-2210-2

– 2 – IEC 61747-40-2:2015 © IEC 2015
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviations . 6
3.1 Terms and definitions . 6
3.2 Abbreviations . 7
4 General . 7
5 Apparatus . 7
5.1 Testing environment and pre-conditioning . 7
5.2 Testing frame . 7
5.3 Test fixture and setup . 9
5.4 Test fixture dimensions . 12
5.5 Loading rate . 13
6 Procedure . 13
6.1 Safety . 13
6.1.1 Hazard – Broken glass. 13
6.1.2 Crush hazard – Only one person may operate the testing frame . 13
6.1.3 Crush hazard – Take care when installing or removing a specimen . 13
6.1.4 Hazard – Press the emergency stop button when an unsafe condition is
observed . 14
6.1.5 Flying debris hazard – Ensure that specimens are installed correctly . 14
6.1.6 Hazard – Protect control cables from damage or disconnection . 14
6.2 Sample . 14
6.3 Individual specimen . 14
6.4 Complete the report . 16
7 Calculations . 17
7.1 Strength calculations . 17
7.2 Statistical calculations . 17
8 Reporting. 18
8.1 Information to be reported for each test . 18
8.2 Information to be made available upon request . 19
9 Specifications . 19

Figure 1 – Testing frame . 9
Figure 2 – Support assembly (side view) . 10
Figure 3 – Support assembly (top view) . 10
Figure 4 – Load assembly (side view) . 11
Figure 5 – Load assembly (bottom view) . 11
Figure 6 – Example load traces for appropriate and inappropriate span settings . 13
Figure 7 – Edge fracture originating from between the load bars . 15
Figure 8 – Edge fracture originating from underneath the load bar . 16
Figure 9 – Surface fracture originating from between the load bars . 16
Figure 10 – Example Weibull plot . 18

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LIQUID CRYSTAL DISPLAY DEVICES –

Part 40-2: Mechanical testing of display cover glass for mobile devices –
Uni-axial flexural strength (4-point bend)

FOREWORD
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International Standard IEC 61747-40-2 has been prepared by technical committee 110:
Electronic display devices.
The text of this standard is based on the following documents:
CDV Report on voting
110/568/CDV 110/608A/RVC
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.

– 4 – IEC 61747-40-2:2015 © IEC 2015
A list of all parts in the IEC 61747 series, published under the general title Liquid crystal
display devices, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site 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.

INTRODUCTION
Mobile electronic devices have become increasingly sophisticated and often include displays
for the purposes of user interface and viewing. Such displays commonly incorporate a
transparent cover glass which aids in protecting the display against the introduction of
damage through routine device transport and use, as well as occasional or accidental misuse.
The purpose of this standard is to provide mechanical testing procedures for cover glasses
utilized in such applications. Such glasses can be strengthened, for example via an ion-
exchange process, which acts to increase mechanical strength through the introduction of a
surface compressive layer.
– 6 – IEC 61747-40-2:2015 © IEC 2015
LIQUID CRYSTAL DISPLAY DEVICES –

Part 40-2: Mechanical testing of display cover glass for mobile devices –
Uni-axial flexural strength (4-point bend)

1 Scope
This part of IEC 61747-40 is a mechanical performance testing procedure for cover glass
used in electronic flat panel displays in mobile devices. This standard is focused on the
measurement of as-received edge strength via uni-axial flexure generated by a four-point
bend.
2 Normative references
The following documents, i
...