IEC 62715-6-1:2014

Flexible display devices - Part 6-1: Mechanical stress test methods

IEC 62715-6-1:2014 is to define the standard test methods to evaluate the mechanical stability of flexible display modules which include displays such as LCD, e-paper, and OLED. It takes into account, wherever possible, the mechanical test methods outlined under mechanical stress.

Dispositifs d'affichage flexibles - Partie 6-1: Méthodes d'essais de contraintes mécaniques

L'IEC 62715-6-1:2014 a pour objet de définir les méthodes d'essais normalisées pour évaluer la stabilité mécanique de modules d'affichage flexibles qui incluent des affichages tels que des écrans LCD, des papiers électroniques et des écrans OLED. Elle tient compte, dans la mesure du possible, des méthodes d'essais mécaniques présentes sous contraintes mécaniques.

General Information

• Status: Published
• Publication Date: 11-Feb-2014
• ICS: 31.120 - Electronic display devices
• Technical Committee: TC 110 - Electronic displays
• Drafting Committee: WG 8 - TC 110/WG 8
• Current Stage: DELPUB - Deleted Publication
• Start Date: 30-Dec-2016
• Completion Date: 20-Apr-2018

Relations

• Revised: IEC 62715-6-1:2018 - Flexible display devices - Part 6-1: Mechanical test methods - Deformation tests
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 62715-6-1


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Edition 1.0 2014-02



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Flexible display devices –
Part 6-1: Mechanical stress test methods

Dispositifs d'affichage flexibles –
Partie 6-1: Méthodes d’essais de contraintes mécaniques


IEC 62715-6-1:2014-02(EN-FR)

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IEC 62715-6-1



®



Edition 1.0 2014-02







INTERNATIONAL





STANDARD







NORME



INTERNATIONALE
colour

inside










Flexible display devices –

Part 6-1: Mechanical stress test methods




Dispositifs d'affichage flexibles –

Partie 6-1: Méthodes d’essais de contraintes mécaniques

















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
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CODE PRIX M


ICS 31.120 ISBN 978-2-8322-1385-8



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® Registered trademark of the International Electrotechnical Commission
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CONTENTS


FOREWORD . 3

1 Scope . 5


2 Normative references . 5

3 Standard atmospheric conditions . 5

4 Evaluations – Visual evaluation of panel image quality . 5

5 Mechanical stress test methods . 5

5.1 General . 5

5.2 Cyclic bending test . 6
5.2.1 General . 6
5.2.2 Purpose . 6
5.2.3 Test apparatus . 6
5.2.4 Test procedure . 6
5.3 Static bending test . 7
5.3.1 General . 7
5.3.2 Purpose . 7
5.3.3 Test apparatus . 7
5.3.4 Test procedure . 7
5.4 Combined bending test . 7
5.4.1 General . 7
5.4.2 Purpose . 8
5.4.3 Test apparatus . 8
5.4.4 Test procedure . 8
5.5 Rolling test. 8
5.5.1 General . 8
5.5.2 Purpose . 8
5.5.3 Test apparatus . 9
5.5.4 Test procedure . 9
5.6 Torsion test . 9
5.6.1 General . 9
5.6.2 Purpose . 9
5.6.3 Test apparatus . 9
5.6.4 Test procedure . 10
5.7 Tension test . 10

5.7.1 General . 10
5.7.2 Purpose . 11
5.7.3 Test apparatus . 11
5.7.4 Test procedure . 11
Bibliography . 12

Figure 1 – Apparatus for diverse cyclic bending test . 6
Figure 2 – Apparatus for static bending test . 7
Figure 3 – Apparatus for combined bending tests consisting of cyclic bending test and
static bending test. 8
Figure 4 – Apparatus for rolling test . 9
Figure 5 – Apparatus for diverse torsion test . 10
Figure 6 – Apparatus for tension test . 11

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INTERNATIONAL ELECTROTECHNICAL COMMISSION


____________




FLEXIBLE DISPLAY DEVICES –



Part 6-1: Mechanical stress test methods



FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62715-6-1 has been prepared by IEC technical committee 110:

Electronic display devices.
The text of this standard is based on the following documents:
CDV Report on voting
110/452/CDV 110/513/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.
A list of all the parts in the IEC 62715 series, under the general title Flexible display devices,
can be found on the IEC website.

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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.



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that it contains colours which are considered to be useful for the correct
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62715-6-1 © IEC:2014 – 5 –


FLEXIBLE DISPLAY DEVICES –



Part 6-1: Mechanical stress test methods








1 Scope


The object of this part of IEC 62715 is to define the standard test methods to evaluate the

mechanical stability of flexible display modules which include displays such as LCD, e-paper,
and OLED. It takes into account, wherever possible, the mechanical test methods outlined
under mechanical stress.
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 62341-5:2009, Organic light emitting diode (OLED) displays – Part 5: Environmental
testing methods
3 Standard atmospheric conditions
The standard atmospheric conditions in IEC 62341-5:2009, 5.3, shall apply unless otherwise
specifically agreed between customer and supplier. The standard atmospheric conditions
shall be a temperature of 25 °C ± 5 °C, relative humidity between 45 % and 75 %, and
atmospheric pressure between 86 kPa and 106 kPa. When all the kinds of tests are carried
out, the temperature condition shall be commented because the temperature is critical for the
bending and rolling stability regarding image quality on the panel.
4 Evaluations – Visual evaluation of panel image quality
The specimen shall be the display module since the final evaluation has to be made based on
panel image quality such as luminance, chromaticity, uniformity, line defect, and point defect.
1
The bending stress may cause the deterioration of image quality on a panel, [1] to [9] . The
allowable critical bending radius of a panel depends on the application of the flexible display.

Therefore, the required critical bending radius will be changed case by case.
5 Mechanical stress test methods
5.1 General
Flexible displays have a diversity of shape in comparison with non-flexible displays. Therefore,
a wide variety of mechanical stress test methods is available, such as a cyclic bending
(folding) or dynamic bending test, a static bending test, a rolling test, a combined mechanical
test and more. The selection of the appropriate test methods shall be based on the
requirement of the application. For each mechanical stress test, the relevant test method
specification shall be stated along with the explanation of the purpose of each unique test.
___________
1
 Numbers in square brackets refer to the Bibliography.

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5.2 Cyclic bending test


5.2.1 General

This procedure is for conditioning the sample under mechanical stress by repeated bending.


5.2.2 Purpose

The purpose of this test is to provide a standard procedure for evaluating the robustness of a

flexible display against a cyclic bending stress which might typically happen in application.

The bending properties might cover several typical parameters of the characteristics of

display panel image quality. The typical parameters of display panel image quality might cover

the luminance, chromaticity, uniformity, line defect, and point defect.
5.2.3 Test apparatus
The cyclic bending test equipment includes the clamp to hold a bending test sample, the
moving part to shuttle, and the control system which regulates the number of cyclic bending,
the moving distance, and the moving speed while testing. The specimen shall be securely
clamped with a gripping part during the test. Several cyclic bending test equipments are
available and shown in Figure 1, [4],[7],[10]. It is not necessary that a certain type of bending
test equipment be preferred but the constant bending radius (r), equal to the radius of the rod,
should be kept during the bending test. The specimen experiences bending stress when the
specimen is shuttled back and forth (Figure 1a)) or while the specimen is folded and unfolded
(Figure 1b)).
Rod Panel Clamp

IEC  0224/14

a)

Panel Clamp
Rod
Frame

IEC  0225/14

b)
Figure 1 – Apparatus for diverse cyclic bending test
5.2.4 Test procedure
The cyclic bending test shall be performed using repeated motion to move regularly between
two points or two states (folded state and unfolded state). For each test, the moving speed,
the bending radius and the number of cyclic bending should be mentioned, because the
characteristics of the image quality displayed on the module might depend on these elements.
The direction in which the specimen faces shall be stated, such as face-up or face-down. For
example, the conditions shall be selected as below:

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62715-6-1 © IEC:2014 – 7 –


r (bending radius): 20 mm, 10 mm, 5 mm, 3 mm, 2 mm, 1 mm, 0,5 mm, 0,2 mm, 0,1 mm


t ( time for one bend and interval ): 0,5 s, 1 s, 2 s, 3 s, 5 s, 10 s


All the conditions shall be reported if the test uses the conditions other than the conditions

given above.


5.3 Static bending test


5.3.1 General


This test is especially applicable for evaluating the bending properties of a flexible display
device by measuring its performance after it remains bent for a certain period of time. Each
specimen is bent at a fixed bending radius for any length of time.
5.3.2 Purpose
This test is to provide a standard procedure for evaluating the bending properties of a flexible
display device under constant stress for a certain period of time. Each specimen is bent at a
fixed bending radius for a controlled length of time.
5.3.3 Test apparatus
The body of the display panel shall firmly adhere to the surface of the test equipment during
the test, where the test equipment should have a round shape with a certain radius as in
Figure 2. The specimen shall be bent at a fixed bending radius for a period of time. During the
test, the FPC (flexible printed circuit) and the driver should be carefully handled in order not
to cause bending damage on them. The COF (chip on film) method is preferable in order to
avoid the occurrence of bending damage on the driver IC during the bending test.

IEC  0226/14

Figure 2 – Apparatus for static bending test
5.3.4 Test procedure
The static time bending test shall be carried out with a fixed bending radius for a certain

period of time. For each test, the bending radius and the period of time shall be mentioned
because the static bending properties of the characteristics of the display panel image quality
might depend on the bending radius and the period of time.
5.4 Combined bending test
5.4.1 General
This test is especially applicable for evaluating two kinds of combined bending properties
(cyclic bending properties and static bending properties (see Figure 3)) of the flexible display
device, after the flexible display remains in the curved shape for a certain period of time and
goes through the cyclic bending condition for a certain period of time in real usage
environment.

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5.4.2 Purpose


The objective of this test is to provide a standard procedure for evaluating the combined

bending properties of cyclic bending and duration time bending. This test aims to take the real

product usage environment into consideration where the real product keeps the panel in a

curved, folded, or rolled shape for a long time when it is used or before it is rolled out.


5.4.3 Test apparatus

The combined bending test utilizes the same apparatus as the cyclic bending test as shown in

Figure 3. The instrument controller shall be capable of stopping the mechanism while the

sample is in a bent state during each iteration of the cycle.

5.4.4 Test procedure
The cyclic bending test procedure is modified to include a pause of adjustable duration
between each iteration of the cycle where the specimen remains in a fully bent state [4]. The
entire test sequence and all of the test conditions of the cyclic bending test part and the static
bending test part shall be reported to ensure reproducibility.

Panel
Rod Clamp
IEC  0227/14

(Cyclic bending)                                      (Static bending)
a)

Panel Clamp
Rod
Frame
IEC  0228/14

(Cyclic bending)                               (Static bending)

b)
Figure 3 – Apparatus for combined bending tests consisting
of cyclic bending test and static bending test
5.5 Rolling test
5.5.1 General
This test is especially applicable for evaluating the rolling properties of a flexible display
module after a flexible display is rolled out, rolled in, or remains in the shape of a roll.
5.5.2 Purpose
The objective of this test is to provide a standard procedure for evaluating the robustness of
the rolling properties of the flexible display panel.

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62715-6-1 © IEC:2014 – 9 –


5.5.3 Test apparatus


The specimen shall be firmly clamped with a gripping part on the roller side and on the

stationary side. The roller shall be reciprocated at a fixed distance, speed, and rolling number

as in Figure 4. The roller side has the slot where the edge of the specimen is inserted and

clamped. The roller repeatedly shuttles along the roller shaft and the specimen does not touch
the plate of the equipment during the rolling test as shown in Figure 4. During the test, the

FPC and the driver shall be carefully handled in order not to cause twist damage on them.

The COF method is preferable in order to avoid the occurrence of twist damage on the driver

IC during the bending test.


Clamp (gripping part)


Sample
FPC
Roller
Roller shaft
Clamp (gripping part)
Sample
Plate
IEC  0229/14

Figure 4 – Apparatus for rolling test
5.5.4 Test procedure
A fixed area of the specimen shall be cyclically wounded and unwounded around the roller.
The winding rate and the cycle count will be controlled. The test conditions and settings shall
be reported to ensure reproducibility.
5.6 Torsion test
5.6.1 General
This test is applicable for evaluating the torsion properties of a flexible display module after
being subjected to torsion during a certain period of time. For flexible displays, torsion is likely
to happen easily during usage.

5.6.2 Purpose
The objective of this test is to provide a standard procedure for evaluating the robustness of a
flexible display device against cyclic torsion stress which might typically happen in the
application.
5.6.3 Test apparatus
The specimen shall be firmly clamped and twisted at a certain degree of torsion angle, as
shown in Figure 5, during the test. The specimen shall be securely clamped with an
appropriate gripping part. During the test, the FPC and the driver shall be carefully handled in
order not to cause twist damage on them. The edge of the sample with the FPC and the driver
IC in the stationary side shall be fixed in order to avoid the occurrence of twist damage during
the bending test. When the sample is twisted, the extra tension is applied on the side of the
sample in addition to the twist tension. Therefore, the moving part in the stationary side shall
move forward and backward during the test because the extra and unnecessary tension
applied on the sample should be removed as shown in Figure 5a) and b).

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5.6.4 Test procedure


The specimen shall repeatedly be twisted counter clockwise and clockwise at a fixed degree

of twisting, a certain speed, and a certain number of twists. The test conditions of the torsion

test such as twist speed and number of twists should be mentioned because the

characteristics of the display panel image quality might depend on the test conditions
mentioned in Clause 4.


Sample Gripping part
  Gripping part

Stationary side

Rotor

Moving part
Moving part
Degree
IEC  0230/14

a)

Fixed end
Rotating end
Moving part

IEC  0231/14

b)
Figure 5 – Apparatus for diverse torsion test
5.7 Tension test
5.7.1 General
This test is applicable for evaluating the tension properties of a flexible display module after
being subjected to a constant tension at the moment of the change between folding and
unfolding and between roll-in and roll-out (see Figure 6).

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62715-6-1 © IEC:2014 – 11 –


5.7.2 Purpose


The objective of this test is to provide a standard procedure for evaluating the robustness of a

flexible display device against cyclic tension stress which might typically happen in the

application.


5.7.3 Test apparatus

The apparatus consists of a fixed and mov
...