Iec 61747 40 2 2015

IEC 61 747 40 2 Edition 1 0 201 5 01 INTERNATIONAL STANDARD Liquid crystal display devices – Part 40 2 Mechanical testing of display cover glass for mobile devices – Uni axial flexural strength (4 poi[.]

IEC 61 747- 40- 2

Editio 1.0 2 15-01

Liquid cryst al display devices –

Part 40-2: Mechanical t est ing of display cover glass for mobi e devices –

Uni-ax ial flex ural st rengt h (4- point bend)

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IEC 61 747- 40- 2

Edit io 1.0 2 15-01

Liquid cryst al display devices –

Part 40-2: Mechanical t est ing of display cover glass for mobi e devices –

Uni-axial flex ural st rengt h (4- point bend)

FOREWORD 3

INTRODUCTION 5

1 Sco e 6

2 Normative ref eren es 6

3 Terms, definition an a breviation 6

3.1 Terms an def i ition 6

3 2 Ab reviation

7 4 General 7

5 Ap aratu 7

5.1 Testin en ironment an pre-con itionin 7

5.2 Testin fame 7

5.3 Test fixture an setup 9

5.4 Test f i ture dimen ion 12 5.5 L adin rate 13 6 Proced re 1

3 6.1 Safety 13 6.1.1 Hazard – Broken glas 13 6.1.2 Cru h hazard – Only one p rson may o erate the testin f rame 13 6.1.3 Cru h hazard – Take care when in tal n or removin a sp cimen 1

3 6.1.4 Hazard – Pres the emergen y sto but on when an u saf e con ition is o served 14 6.1.5 Flyin de ris hazard – En ure that sp cimen are in tal ed cor ectly 14 6.1.6 Hazard – Protect control ca les f om damage or dis on ection 14 6.2 Sample 14 6 3 In ivid al sp cimen 1

4 6.4 Complete the re ort 16 7 Calc lation 17 7.1 Stren th calc lation 17 7 2 Statistical calc lation 1

7 8 Re ortin 18 8.1 Inf ormation to b re orted for e c test 18 8.2 Inf ormation to b made avai a le up n req est 19 9 Sp cif i ation 19 Fig re 1 – Testin f rame 9

Fig re 2 – Sup ort as embly (side view) 10 Fig re 3 – Sup ort as embly ( o view) 10 Fig re 4 – L ad as embly (side view) 1

Fig re 5 – L ad as embly (b t om view) 1

Fig re 6 – Example lo d traces for a pro riate and ina pro riate sp n set in s 13

Fig re 7 – Ed e f racture originatin f rom b twe n the lo d b rs 15

Fig re 8 – Ed e f racture originatin f rom u derne th the lo d b r 16

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International Stan ard IEC 617 7-4 -2 has b en pre ared by tec nical commit e 1 0:

Electronic display devices

The text of this stan ard is based on the f ol owin doc ments:

Ful inf ormation on the votin for the a proval of this stan ard can b f ou d in the re ort on

votin in icated in the a ove ta le

This publ cation has b en draf ted in ac ordan e with the ISO/IEC Directives, Part 2

A l st of al p rts in the IEC 617 7 series, publ s ed u der the general title Liquid cryst al

displ ay d evic s, can b f ou d on the IEC we site

The commit e has decided that the contents of this publ cation wi remain u c an ed u ti

the sta i ty date in icated on the IEC we site u der "ht p:/ we store.iec.c " in the data

related to the sp cific publ cation At this date, the publ cation wi b

Mo i e electronic devices have b come in re sin ly so histicated an of ten in lu e display

f or the purp ses of u er interace an viewin Su h display commonly in orp rate a

tran p rent cover glas whic aid in protectin the display again t the introd ction of

damage throu h routine device tran p rt an u e, as wel as oc asional or ac idental mis se

The purp se of this stan ard is to provide mec anical testin proced res f or cover glas es

uti zed in s c a plcation Su h glas es can b stren thened, for example via an ion

-ex han e proces , whic acts to in re se mec anical stren th throu h the introd ction of a

s race compres ive layer

LIQUID CRYSTA L DISPLA Y DEVICES –

Part 40-2: Mechanical testing of display cover glass for mobi e devices –

Uni-axial flexural strength (4-point bend)

This p rt of IEC 617 7-4 is a mec anical p r orman e testin proced re for cover glas

u ed in electronic f lat p nel display in mo i e devices This stan ard is f oc sed on the

me s rement of as- eceived ed e stren th via u i-axial flex re generated by a four p int

The f ol owin doc ments, in whole or in p rt, are normatively ref eren ed in this doc ment an

are in isp n a le f or its a pl cation For dated ref eren es, only the edition cited a pl es For

u dated referen es, the latest edition of the referen ed doc ment (in lu in an

amen ments) a pl es

IEC 617 7-4 -1, Liquid crystal d ispl ay devic s – P art 4 -1: Mec a ic l testin of d isplay

c v r gl as for mo il e d evic s – Guidelines

group of sp cimen s arin a common p digre (s c as man f acturin proces an p riod

of prod ction), f or whic fai ure statistic can b generated an re orted

Note 1 to e try: For gla s s with ut a c mpre siv s ra e la er, stre gth c n b e u te to th f ra ture stre s.

In c s s wh re n n-ln aritie pre e t a s ita le c n ersio fom lo d to stre gth (or stre s), lo d at fa ture

s o ld in te d b re orte

3.2 Abbre iations

PTFE p lytetraf l oro th lene

This test me s res ed e stren th by f orcin a p ir of p ral el lo d b rs (an i s) throu h a

sp cimen that is s p orted by a p ir of p ral el s p ort b rs The two p irs of b rs s al b

p ralel an the a pl ed force s al b p rp n ic lar to the s r ace formed by the s p ort b r

p ir The lo d at f acture are me s red an con erted to stren th Stren th calc lation are

f ou d in Clau e 7

The test is a pl ed to a sample of several sp cimen The sample statistic of the stren th

values are defined in Clau e 7 The statistical values to b re orted or sp cified are given in

Clau es 8 an 9

The sp cimen to b tested are typical y 4 mm to 6 mm in width an 6 mm to 1 0 mm in

len th, with thic nes ran in fom 0,5 mm to 2,0 mm When the sp cimen is placed on the

s p ort b rs, a p ir of o p site ed es s al b alg ed to b p ralel with the s p ort b rs

Bef ore the sp cimen is placed on the s p ort b rs, the s r ace that wi contact the lo d b rs

is covered with a layer of p lymeric ad esive ta e to preserve the f racture s rf ace, red ce the

s at erin of glas f agments up n f racture, an minimize contact damage The s p ort rod

are also covered with PTFE tap an may b rol ers, also to minimize contact damage an

f riction

The general req irements of the a p ratu are given in Clau e 5 Ap aratu dimen ion can

b af fected by sp cimen dimen ion These relation hips are outl ned in 5.4 It s ould b

noted that direct comp rison can ot b made b twe n sp cimen tested u der diff erent

a p ratu /f i ture dimen ion or at dif ferent cros he d traverse rates

Testin proced res are given in Clau e 6

It is as umed that al me s rements are p rf ormed by p rson el s i ed in the general art of

mec anical pro erty me s rements Furthermore, it s ould b as ured that al eq ipment is

s ita ly calbrated as is k own to s i ed p rson el an that record of the cal bration data

an trace bi ty are ke t

5.1 Te ting e vironme t a d pre-conditioning

The stan ard testing en ironment is sp cif ied in IEC 617 7-4 -1 Sp cimen s al b stored

in s c an en ironment for at le st four hours b f ore testin

5.2 Te ting frame

The testin fame provides the asp cts needed for the control ed vertical movement of some

mec anical elements relative to a test fixture s rf ace It also in lu es a lo d cel to in icate

the a pl ed f orce of these mec anical elements again t other mec anical elements that are

atac ed to the test s rf ace an detectors to in icate displacement f om the start of motion A

control er is also req ired to co rdinate the neces ary motion These may b driven by

external comman s or by lo d cel resp n es Examples of motion directives in lu e:

• Jog up or down

• Slow man al up or down u ti the sto buton is pu hed

• Return to a preset start of test.

• Traverse downward at a fixed rate u ti facture is detected, then sto

• Emergen y sto

In ad ition to providin motion control an me s rement of lo d, the control er s al , at

minimum, re ort the f racture lo d, al ow the setin of the lo d rate an the display lo d as a

f un tion of time an /or def lection f rom the start of the test Other fe tures can in lu e:

• The colection, organization, storage, an re ortin information entered for the sample, its

sp cimen , f racture lo d data, an statistical analy is res lts

• Calc latin in ivid al sp cimen facture stren th u in data input for the sp cimen an

the facture lo d

The main stru tural elements of the testin f ame s al b made of ste l with dimen ion

large enou h so compl an e is es ential y zero with resp ct to the maximum force that wi b

a pl ed This maximum f orce de en s on the sp cimen b in tested, but s ould general y b

The lo d cel s al b cal brated again t a k own weig t, force gau e or lo d cel an b

l ne r to within 1 % over the maximum a pl ed force The lo d cel s al be ca a le of b in

reset to zero af ter the atac ment of mec anical elements to it b f ore the a p ratu setup is

complete It s al also in lu e an atac in mec anism

Fig re 1 i u trates some of the elements of the testin f ame

Subclau e 5.3 outlnes the generic test f i ture elements an setup proced re Subclau e 5.4

identifies the req irements of the dimen ional c aracteristic , whic can de en on sp cimen

c aracteristic

The primary test fixture elements are the s p ort as embly an the lo d as embly These are

i u trated fom Fig re 2 to Fig re 5 Other test fixture elements in lu e:

• Clamps u ed to f asten the s p ort as embly to the test f ame testin s race

• PTFE ta e u ed to cover the s p ort b rs

• Mac ined in tal ation gage to al g the s p ort an lo d as embl es

• Micrometer with f lat an i f aces an resolution of 0,0 2 mm or b t er

NOT Th k y to th leters is pro id d in Fig re 5.

Figure 2 – Sup ort a s mbly (side view)

NOT Th k y to th leters is pro id d in Fig re 5

Fig re 3 – Support a s mbly (top view)