1、BSI Standards PublicationLiquid crystal display devicesPart 40-2: Mechanical testing of display cover glass for mobile devices Uniaxial flexural strength (4-point bend)BS IEC 61747-40-2:2015National forewordThis British Standard is the UK implementation of IEC 61747-40-2:2015.The UK participation in
2、 its preparation was entrusted to TechnicalCommittee EPL/47, Semiconductors.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions ofa contract. Users are responsible for its correct a
3、pplication. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 84402 7ICS 31.120Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Commit
4、tee on 31 January 2015.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARDBS IEC 61747-40-2:2015IEC 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 flex
5、ural strength (4-point bend) INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 31.120 ISBN 978-2-8322-2210-2 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. BS IEC 61747-40-2:2015 2 IEC 61747-40-2
6、: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 se
7、tup . 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
8、 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
9、 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 Fi
10、gure 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 Figu
11、re 9 Surface fracture originating from between the load bars . 16 Figure 10 Example Weibull plot 18 BS IEC 61747-40-2:2015IEC 61747-40-2:2015 IEC 2015 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ LIQUID CRYSTAL DISPLAY DEVICES Part 40-2: Mechanical testing of display cover glass for mobile devices
12、Uni-axial flexural strength (4-point bend) 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 co-operation on all
13、questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publica
14、tion(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC
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19、tion bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall a
20、ttach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal f
21、ees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publica
22、tion. 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. International Standard IEC 61747-40-2 has been prepared by technical committee 110: E
23、lectronic 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 drafte
24、d in accordance with the ISO/IEC Directives, Part 2. BS IEC 61747-40-2:2015 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 th
25、is 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 t
26、his publication may be issued at a later date. BS IEC 61747-40-2:2015IEC 61747-40-2:2015 IEC 2015 5 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 transparen
27、t 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 g
28、lasses can be strengthened, for example via an ion-exchange process, which acts to increase mechanical strength through the introduction of a surface compressive layer. BS IEC 61747-40-2:2015 6 IEC 61747-40-2:2015 IEC 2015 LIQUID CRYSTAL DISPLAY DEVICES Part 40-2: Mechanical testing of display cover
29、 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
30、uni-axial flexure generated by a four-point bend. 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 editi
31、on of the referenced document (including any amendments) applies. IEC 61747-40-1, Liquid crystal display devices Part 40-1: Mechanical testing of display cover glass for mobile devices Guidelines IEC 61649:2008, Weibull analysis 3 Terms, definitions and abbreviations 3.1 Terms and definitions For th
32、e purposes of this document, the following terms and definitions apply. 3.1.1 specimen individual piece of glass to be tested to failure 3.1.2 sample group of specimens sharing a common pedigree (such as manufacturing process and period of production), for which failure statistics can be generated a
33、nd reported 3.1.3 sample size number of specimens in a sample 3.1.4 nominal value value about which a tolerance range is specified 3.1.5 strength normalized load at which fracture occurs BS IEC 61747-40-2:2015IEC 61747-40-2:2015 IEC 2015 7 Note 1 to entry: For glasses without a compressive surface l
34、ayer, strength can be equated to the fracture stress. In cases where non-linearities prevent a suitable conversion from load to strength (or stress), load at fracture should instead be reported. 3.2 Abbreviations PTFE polytetrafluoroethylene 4 General This test measures edge strength by forcing a pa
35、ir of parallel load bars (anvils) through a specimen that is supported by a pair of parallel support bars. The two pairs of bars shall be parallel and the applied force shall be perpendicular to the surface formed by the support bar pair. The loads at fracture are measured and converted to strength.
36、 Strength calculations are found in Clause 7. The test is applied to a sample of several specimens. The sample statistics of the strength values are defined in Clause 7. The statistical values to be reported or specified are given in Clauses 8 and 9. The specimens to be tested are typically 44 mm to
37、 60 mm in width and 60 mm to 110 mm in length, with thickness ranging from 0,55 mm to 2,0 mm. When the specimen is placed on the support bars, a pair of opposite edges shall be aligned to be parallel with the support bars. Before the specimen is placed on the support bars, the surface that will cont
38、act the load bars is covered with a layer of polymeric adhesive tape to preserve the fracture surface, reduce the scattering of glass fragments upon fracture, and minimize contact damage. The support rods are also covered with PTFE tape and may be rollers, also to minimize contact damage and frictio
39、n. The general requirements of the apparatus are given in Clause 5. Apparatus dimensions can be affected by specimen dimensions. These relationships are outlined in 5.4. It should be noted that direct comparisons cannot be made between specimens tested under different apparatus/fixture dimensions or
40、 at different cross head traverse rates. Testing procedures are given in Clause 6. It is assumed that all measurements are performed by personnel skilled in the general art of mechanical property measurements. Furthermore, it should be assured that all equipment is suitably calibrated as is known to
41、 skilled personnel and that records of the calibration data and traceability are kept. 5 Apparatus 5.1 Testing environment and pre-conditioning The standard testing environment is specified in IEC 61747-40-1. Specimens shall be stored in such an environment for at least four hours before testing. 5.
42、2 Testing frame The testing frame provides the aspects needed for the controlled vertical movement of some mechanical elements relative to a test fixture surface. It also includes a load cell to indicate the applied force of these mechanical elements against other mechanical elements that are attach
43、ed to the test surface and detectors to indicate displacement from the start of motion. A controller is also required to coordinate the necessary motions. These may be driven by external commands or by load cell responses. Examples of motion directives include: Jog up or down. Slow manual up or down
44、 until the stop button is pushed. BS IEC 61747-40-2:2015 8 IEC 61747-40-2:2015 IEC 2015 Return to a preset start of test. Traverse downward at a fixed rate until fracture is detected, then stop. Emergency stop. In addition to providing motion control and measurement of load, the controller shall, at
45、 minimum, report the fracture load, allow the setting of the load rate and the display load as a function of time and/or deflection from the start of the test. Other features can include: The collection, organization, storage, and reporting information entered for the sample, its specimens, fracture
46、 load data, and statistical analysis results. Calculating individual specimen fracture strength using data input for the specimen and the fracture load. The main structural elements of the testing frame shall be made of steel with dimensions large enough so compliance is essentially zero with respec
47、t to the maximum force that will be applied. This maximum force depends on the specimens being tested, but should generally be less than 10 kN. These elements include: the testing surface, vertical support columns, a cross head, motion tractors within the support columns, load cell assembly and atta
48、chment mechanisms. The minimum and maximum rates of motion shall encompass the range of 0,001 mm/min and 1 000 mm/min. The controller shall sample the load cell and displacement detectors at a minimum rate of 10 kHz. The load cell shall be calibrated against a known weight, force gauge or load cell
49、and be linear to within 1 % over the maximum applied force. The load cell shall be capable of being reset to zero after the attachment of mechanical elements to it before the apparatus setup is complete. It shall also include an attaching mechanism. Figure 1 illustrates some of the elements of the testing frame. BS IEC 61747-40-2:2015IEC 61747-40-2:2015 IEC 2015 9 Key A Test surface B Support columns C Cross head (moves up and down) D Load cel
