CA1262609A - Method of manufacturing a recordable optical storage plate - Google Patents

Abstract

ABSTRACT:
Method of manufacturing a recordable optical storage plate.

In a method of manufacturing an optical storage plate (1) which consists of at least a substrate base plate (2) and a cover plate (7) provided at at distance from same, both are manufactured from a synthetic resin by means of a stamper according to an injection moulding or compression moulding process. The plates, at least in the outer edge area, are bonded together by welding via integrally formed distance means such as lugs (5). The substrate base plate (2) comprises an information layer (4) and in its area a microstructure which is copied from a stamper (10) which is provided at least in the outer area with recesses (16) to form the lugs (5). The recesses (16) in the stamper (10), or in a negative mould used for the manufacture of the stamper, are produced by means of high energy radiation (15, 18) focused at a given depth below the surface of the stamper or the mould, respectively, by melting and evaporating the material of the stamper or mould, respectively.

Figure 1.

Description

o~
2010~-8060 The invention relates to a method of manufacturing a stamper for the moulding oE an optical storage plate, which optical storage plate comprises at least one substrate base plate and one cover plate provided at a distance therefrom, which plates are both manufactured from a synthetic resin by means of the stamper according to an injection moulding or compression moulding process and are welded together at least at their outer edge areas via integrally formed meltable distance means, the substrate base plate comprising an information layer and a microstructure at that area which is copied from the stamper, the stamper being provided with recesses at the outer edge area to form the meltable distance means.
Optically readable, plate-shaped information carriers, as they have been used for a long period o~ time as laser video discs, digital audio discs or storage plates, enable an extremely high storage density o~ the information to be stored and hence become more and more important for the data technique in which, however, it is required that the digital information to be stored can be recorded by the operator himself of such a device.
~0 As is shown, for example, in EP-PA 0,094,273 it is known in such optical storage plates to use a sandwich construction. By the sandwich construction it is achieved that on the one hand information can be recorded in the sensitive recording layer through the substrate base plate using minimal laser power and on - the other hand the storage layer is sufficiently protected from '~

2~10~-8060 damage during the handling. On the basis of the mode of operation of the information layer of such known plates an empty space is required between the substrate base plate and the cover plate. In the sandwich construction known from the above-mentioned : la Yj~

PHD 8 5 4 8 1 ;~ 2 ~ ,1 g B 6 EP . PA tha di9tAnc~3 b~ tweerl the ~u~tr~t~ ~a8~ pl~te aIld ~he cover plQte 1~ ~3n~ured ~y di~tanos m~n~
comprl~ln~ inte~;ra~y ~orm~d wid~ lUg8 ~ In ~ddl~ion9 smaller1 thln 1 u~ are pro~ ,ded ~n top o;E ~he w~d0 lu~
5 which ~3r~re :for weldlng pU~'pO~3eB, In bhi~ Xnown ~ndwich ~on~tructiO~ th~ 3 th~ lu~zs ar~ nece~ary sinca ~or welding it i5 lmportant t4 he~e~ a~ ~5mall o~ntRct ~urfe.cs~
pos~ible a~d ~ n thl~ mE~mcr to u~e Q minim~m ef energy since ~upply of teo much ener~y will. load to warpln~
lO of ~he plsta~ .
For th~ manu~ture o:E ~t l~aet the thi~ lug0 of the pl~teo~ r~e~e~ ar~ requir~3d in tho At~mper. Nvrm~lly~
~leotroplatec~ ~temper~ are u~ed wh~ch u~u~lly oon~ist o~
rl~clçO n thee~ ~tE~mpo;r~ a~ooesae~ must 4c pro~rlded lS for ~uboequent produotion o~ the lu~a in tho ple~to~ ~t ha~
bson fou~d that the known method~ o~ manu~acturi~ tho rec~e~ m~y re~ult in cont~min~t~on~ o~ th~ HteLmpo~ he3e ar~ formed ln that durl~ 1;h~ ma~uf~ctur~ of the roo~s~e~
mQterl~l mu~t b~ r~movod whioh oQn ea~lly l~nd ln the microstruoture, Moreover, e~oh timo bhe s~mpo~ i~ h~ndled, the po~iblllty o~ dama~o or oontam~n~tion of ~id mloro-struotur~ ~xi~t~, For th~ manll~actur~ o~ the roo~s~ ln the ~tump~r it i~ mor~o~o~ im~ortant b~at ther ~r~ ~o~mod Rocur~tely ~l~oo the ~ub~qua~Lt lug~ mu~t hAv~ ~ mo~t 26 accuret~lr de~ln~d a~d ~n ~L~ sm~ll a~ po~ible ¢ont~ot ~ur~oo w~th the oppo~itely located plato. Moroo~r ~t ~hc~ul~ be énsur~d that in t:~e manu~c,bure Or the ~tor~
plate no lnte~nal ~t~ aa Are fcrmed w~io~ may ra~ult in w~rpl~ o~ the plabe~

3~ It iB ~ho ob~ct o~ t~ ~nv~tio~ to p~ovld~
an improved method o~ m~nuf`aoturl~ rooo~d~blo optioal ~torage platR~ in whiah thel r~ces~c~ ¢an be ~orme~ in the stamper in a rapid a~d r~tl,on~l manner wlb~out ~nma~s or o ontQmirl~ ti on Aooo~dln~ to the ~n~ntio~ thi~ ob~oob i~
aohiov~d in thu~ the reoeo~le~ i~ the ~tampor or in R
negR~lve mould u~ed for bhe, mnnu~acture o~ tho ~b~mper ~ro 20lO~ 60 produced by means oE high energy radiation focused at a yiven depth below the surface oE the stamper or o tAe mould by melting and evaporating the material oE the stamper or mould in a substantially circular track at the edge of the stamper or mould~
An essential advantage of this method is that the recesses are produced without contact so that internal stresses in the stamper are avoided. The form of the recesses depends on the three parameters of the high energy radiation which can be influenced. These three parameters are: intensity of the radiation, duration of the effect of the radiation, and depth of focusing of the radiation. By suitably matching said three parameters a desired shape of the recesses can be produced empirically while taking into account further influences, for example, of the material. A negative focusing depth should in principle not be excluded.
In plates having a central hole, distance means are generally provided both in the outer edge area and also in the area of the central hole, whereas in plates without a central hole then are required only in the outer edge area.
According to a further embodiment of the invention it is ensured that the dimensions of the recesses and the distance means, respectively, are such that they ensure the desired distance between the substrate base plate and the cover plate and, for weIding, ensure a point or line contact with the respective other plate.
An essential advantage of this embodiment is that the above-described parameters in the manufacture of the recess are ~ 010~-8060 adjusted so that the subsequent distance means serve both for the spacing of the two plates and for the welding. By using high energy radiation and modulation thereof a discontinuous shape oE
the recesses and distance means, respectively, is possible. The discontinuous distance means or lugs may be shaped and arranged so that after welding a hermetically sealed cavity is Eormed between the two plates.

3a '.~

~;2~

P~ ) 85l~81 4 ~5 ~ 5 7 1 ~g6 AGcordin~ to ~ ~ur~her modi~i0d embod-lment o~
tho irlver~tion t1n~ hi~h on~r~y radiatio~ nl~r ~d~ u~y be produoed by ~ er~
Accorclin~ to ~ ~urther modi~ d em~odim~3rlt o' tha ~i inveIltlon it i9 en~5ured thQ1; dur!ng th0 mQnu'~¢tu~e o' the rece~e~ the ot~mpo~ ~ the mould, raopectivhly7 ~r~3 ar~ang~d ~o as to be ~t~tio~lary ~nd the l~aer b~3am i9 guided over the ~tamp*r oY~ r~oul~, re~pectlvelr~ in a c~roulE~r traok~ by meeLIl~ o~ a oontrolle~blo optl¢al syE3t*m.
Ih~ ~tamper or the mould~ re~;peoti~olr~ mu~t ba suppor~e~ in ~ de~ioe~, ~ prl30i~e mo~oment ~nd rot~tion~
re~pec~l~ely~ o~ thi~ device i~ not neoe~ary ~ooo~di~g to the m~thod, Th~ npli~ie~ the con~tructio~ o~ the dev~ce and ~coeler~tes the m~nu~o1;u~e o~ th~ rece~0~ ln the lS ~t~mper or the mould~respeci;l~elr~ si~ce the controllable optio~l ~y~tem aa~ ~uide the la~er ~eam in ~ su~tantlally inertlAle~o man~ar to bhe re~pec~ive des~rad pooitlon~
The lnven~lon wLll be de~oribed in ~reat~r detail with refere~ce to the drawing, ln which ~i~ure 1 i~ a ~ee~al ~lew of a re¢ord~le optlcal stor~ge plute, ~igure ~ i~ ~ pl~n Ylew of ~hc ~tor~e pl~t~
shown in Fi~ure 1~
Fl~ure 3 i~ a rlr~3t ar~:an~Samcnt ~or th~3 2~ ma~u~acture o~ gr40ve~ ped reoe~es in at~mpers and mould~
r~p3ctl~ely~
F~gure 4 19 ~ pa~-LQl ~eÇtionBl view 0~ ~ ~roove-ahape~ reca~ in a ~tamper ~nd a mould~ re~peotively~
Fl~ur~ ~, 6 ~nd 7 ohow di~r~mmatic~lly the 30 ~nu~c~ure o~ th~ di~tanoe m~an~ 3ynthetio re~in pl~te~ .
~ ~ur~ 8 ~OWb th~ di~tanoe mean~ o~ ure r welded to ~ plate~
~ i~ure 9 ~how~3 a l3eoon~ arra~ement ~or the 35 manu~Qcture o~ ~roo~e-sh~ped reoe~se~ in a ~tamper o~ mouldA
The ~o~ion~l ~iew o~ Fi~ure 1 o~ the reoordable opbloal otorage pl~to 1 ~ho1~e ~ oub~trate b~0e pl~to 2 , .

~ 3 PHD B5~81 5 ~5.g.1g~6 havlng ~ oentra~ hole 3 w~lch on ito upper ~ide ha~ n circular recordin~ l~y~r 4 l~rrQngod oen~r~lly ar~und the centre hole 3. Out~lde th~ :r~oordi~ lar~r ~ th~ ~u~tr~te base pl~te 2 in the out~r e/~ re~ ~d in th0 inncr oentre hole ~re~ i~ pro~lded wlth oiroulQr di~t~no0 me~n~ or lugj 5 ~nd 6 t~e h~i~ht o~ r~ ich ~ ~ e~sentlally l~r~er t~n the thicknes~ o~ the recordlng layer 4. ~n the ar~
o~ the lug~ 5 ~nd 6 the ~u~trate bQ~e pl~te 2 i~ welded to ~ cover plate 7 oovering it~ uppe~ ~lde ~nd aloo 0 compri~in~ a oe~tre hole 3 ;i~ a~reame~t wl th tho sub~trato ba~e pla~ ~. Th~ ~ub~trate ba8e pl~te Z and t~o co~er plate 7 oon~i~t o~ a synthetlc re3~ or example~ polyoQrbonQtog at lea~t the ~ynt~etlc re~ o~ the ~ub~tr~te ba~e plata 2 bein6 tran~parent~
A~ urt~er illu~trate~ in t~e plan ~iew o~
the record~ble optlcAl ~borage plQte 1 ~hown in Figure 2 7 the annular di~t~noe mean~ 5 and 5 mu~t ~y no mea~
rep~sent a closed ring but may a1YO be oompo~d o~ a ~aller or lar~er numb~r o* lu~ ~ectlon~ kept a~ ~ mutuQl di~t~nce. Optlonally ~t ~hould be ~n~ured th~t a~t~
welding a hermetioall~ ~ealed oavity i~ ~ormed between ~he pl~te~.
In p~i~olple the poB311:~ility al~lo exi~t~ to ri~idly arr~n~e the lu~ 5 and 6 to th0 cover pl~te 7 25 in~tead o~ to bh~ substr~t0 base plate 2c ~t iB al~o po~sible to oonetruct bot~ the eub~tr~te ba~e plabe 2 ~d the co~er pl~te 7 wlth a~Mular lu~ 5 ~nd 6 whioh are contrio with re~pect to eAc:h o~her. In ~ plate whloh oan be uoed on two ~ide~ the two plab~s welded together m~y b~
construotod to b~ idenbio~l ~nd oon89qu~ntl~ oan ~e manu-~acture~ wit~ tha u~e o~ only o~e stRmper. The lu~s may optionQlly be ~rr~nged ~o ~:hat the lug~ of the two plats~
~i~ one within bhe obherO
The wel~ g operati~n wh~ch by w~y o~ example i~
36 per~o~med ulbra~onicRlly i8 the ~Qm~ ln ~11 the~e embedl-ment~, In ordor ~o oon~ume the ~m~llest ~mount o~ ener~y so a~ to prevent bha pos~ibili~y e~ w~rp:ln~ o~ the ~torage PHD 85481 ~ 25, ~ 86 plate ~ tha lug~ ~ and 6 ~d~nt~geeu31y on~Ly have ~
width ln the erd~3r o~ m~eni. tude e~ 1 mm. Tho ~el~ht m~y ~e r~strlcted to ~ :~r~ct.l~ of~ 1 mm~ It ~heulcl howe~er be en~u~ed that tha hel~ht o~ the ciroul~r cavity ~ at the ~rea o~ the reoor~in~ l~ye~ ~ is uu~i¢iently lar~er than the thioXne~ o~ the reoording l~yer 4 in order th~t ln ~perntin~ condition~ it i~ ~ub~t~ntl~lly pre~cn~ed that the plateu ~ n thc reco~ding l~yer ~rea oontacb e~oh o~her 9 A~ Ql~eady nebod ~ miorootructur0 i~ to b~
produced ~n the ~re~ o~ the r~¢~rding laye;r 1~ which may h~ve th~ ~orm o~ ~ writing beam ~uide tr~ok. For the m~nu~aotu~e o~ ~id writ ~g beam guide track it i~
advantageou~ to m~n~acture the 8ubs~r~te ba~o plato 2 by mo~n~ o~ an in~ectlon mouldin~ prooeao w~ile u~ing ~tamyer~
derlved from a ma~tor by el~otroplating. A8 i~ sh~wn dl~rammatio~lly in Figure 3, the lug~ 5 and 6 ~t th~
pl~te ar0 obt~ined oimultQneou~ly by me~n~ o~ such sta~per, 2~ Fisure 3 ~how~ a t~rnt~ble 9 h~ving ~ mo~lded portion 11 ~pporting a st~mper 10 in who~ pin 12 the otQmpe~ 10 1~ oentred with i t~ centre hole. The turntable g ~ rotatfld by mean~ o~ otor 13 and durin~ ~he rotatlon the groo~e-~h~p~d :reoe~e~ oorreopondin~ to the 26 lu~ 5 ~n~ ~ shown in Figurls 1 are produood in bho ~tam~er 10 by meltin~ and ev~porQti~ o~ the stQmper m~te~ial by mean~ o~ a l~ser 14 who~ ht be~m 1 ~ ocu~ed on t~e ~ur~Qce o~ the ~tamper 10. T~o bop o~ the ~tamper m~y bo oovered b~ m~n~ o~ a templttte in a m~nner nob ~how~ in bhe 30 Fi~ure to protoob the mlcro)~b~uotur~I
In the e~l~r~ed s~ot~on AS ~w~ in Figu~ 4 the ~oore-~hapod rees~s 16 pr~duc~d by the laser 14 ~an be 3ee~, ~uring ~o~lding ~he ~ubs~r~te ba~e plate 29 the do~i~ed lug~ ~ and 6~ ~esp~o~ively, are ~`orm~d in 35 accord~oe with b~o ~eetion~ ew o~ ure 5 a~ a ~ult o~ the ~roo~e~haped reoe30 16 ~nd ar~ ~ubseque~tly rel~a~ed from the mould ~ hown ln the ~e~tional vi~w o~ ure 6~

2~3~9 PHD 85481 7 ~505~19~6 F~ura 7 :L~ ~ ~eot;:lon~l view o~ the lu~ 8}~0wn in Fi~ur~ 6 taken on the line VII~VII ~ I~ mQy be ~oen bh~t the lug~ v~ewod in ~he direotien o~ travel o;~ the pl~te, i~ ~ubsbantially aemi-oylinclrio~l, A~ a :r7e~ult o~ el, 5 line contact between the lug Qnd t~e oover plate :i3 eno ured, ~ i~ure 8 a~;~in ~how~ 'che l ug o~ Fl~ure ~ but bh~ ~ time ln a, condlbion 12~ w:hioh lb i~ weldç~d to a oove~
plat ~ ~
1~ P'l~u~a ~ ~ow~ a ~eoo~d arrangen~ent ~or t~e mQ~Uf~aCtUre of~ groove--~h~ect ~ece~e~ ~n ote.mpera ~nd mould~9 rospeot~vely. For the m~r~uf~cture o~ th~ r~3e~e~
16 ln the ~tamper 10 t~e l~,tter l~3 pro~ided ~o eL8 to b~
st~t~onELryr A l~e~ b~m 18 o~ er 17 l~ ~}~3wn 15 on the 9tampe~ 10 ~ ~ a mov~le l~n~ ZU o~ ~ oo~trollable optical ~y~tem 19 where reoes~e~ 16 0.re prod~ced ~y meltln~
~;ld evaporatln~ a~ a re~ulb of the uo tion o~ the la~er 4eam, In ~ convention~l manner ~ ~tQrnper 10 ~l~ow~ ~n FiOEura~ ~ Rnd ~, re~peot~e~.y~ i~ obt~ined ~om a ma~ter 20 plate. ln th~t fir~t a father mould l~ m~;~u~0,0ture~1 ~rom the m~ster pl.~te. From ~ thar mould whioh i8 a negatlve o~
the original pre~ent in t~e ma~ter a mother mould repre~en-ting a positive i~ o4bainod~ From the mother mould fin~lly se~reral e.~aln ne~e.tive st~mpera may be m0.~u~aotUr4d. I~l~
2~ pro~rldes the poY~ ty o;f produoing the g~oove-~hape~
reoe~ee~ to be made by th~ l~Yer beam al~eady ln tl~o fe.th~3r mould beoau~e thcn the de~ired ~oove ~h~ped r~oe~se~ ~re~ 80 0.utomatioally p~e89nt i~ all the ~tamper~
deri~d ~rom bhe ~athbr mou~.d y,~;~, the mot~er mould~
~ f`or reasono o~ preoi~lon ~nd the amoothne~s o~ ~h~ ~u~ace~ a oompre~ioTl mouldln~ or in~ootio~
mouldi~g prooe~ io u~ed i~ t~e manU~Qoture o~ the oove~
plate 7, Ytamper~ whioh are u~ed for thi~ purpo~e may 40 u~ed ha~l~ lug~ 5 ~,~d 6 to be pro~rldod ln a oo~re~po~din~
35 mE~nnar with groo~ 3hapod receE~8e~, In aocordanee with a ~tampar ~ the h~l~ o~ ths mo~lld or ln~eoblon mould ~ormia~
~he lowor olde o~ bhe oov~ ~late 7 m~y be provi~d with PHD 85l~81 8 ~ 5~1g86 the de~irod ~roove~~h~ped rece89~8 b~r me~ns o~ a h~ ~ h energy la~er be~m.
The re~e~o~ are not neoe~s~rllr ~ormod ln ~ne ~ixL~lo opere.tioll by the 1~ 3~ bea.m, Xn~ea~ e l~er b be~m m~ make ~everal pa.~el~ o~rer ~ho ~eLmper, progr~s~i~el~ fos~min~ the rl30e~e~ 0 By ~r~rrin~ on8 or more o~ the eQrl I er mention,3d vari~ble~, dl~erent pas~e~
m~y be u~3ed to ~orm pro~ile,~ rece~33e~ 1U8, lu~8 1~8 kno~m ~em ~he earlier montlon~d EP-PA 070~49273 m~y ~o :forme~
consistin~ of a wider p~rt and ~maller p~rts.
~ lle reoe~e~ ~orme~ by the l~Lser be~m may be conti~uou~ ence o;E~ a ce~tr~ hole, a in~e continuou~3 rec:e~ on the out0r edge could be ~u:~;Eicient.
The expre~ion reoe~ea i~ m~3ant to inolude on~ gle 15 rece~8 .

~0 .... ..

Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method of manufacturing a stamper for the moulding of an optical storage plate, which optical storage plate comprises at least one substrate base plate and one cover plate provided at a distance therefrom, which plates are both manufactured from a synthetic resin by means of the stamper according to an injection moulding or compression moulding process and are welded together at least at their outer edge areas via integrally formed meltable distance means, the substrate base plate comprising an information layer and a microstructure at that area which is copied from the stamper, the stamper being provided with recesses at the outer edge area to form the meltable distance means, said method comprising forming the recesses at the outer edge of the stamper by means of high energy radiation focused at a given depth below the surface of the stamper by melting and evaporating the material of the stamper in a substantially circular track at the edge of the stamper.

2. A method as claimed in Claim 1, characterized in that the recesses and the distance means, respectively, have such dimensions that they ensure the desired distance between the substrate base plate and the cover plate and, for welding, ensure a line contact or point contact with the opposite plate.

3. A method as claimed in Claim 1, characterized in that the high energy radiation is produced by a laser.

4. A method as claimed in Claim 3, characterized in that in the manufacture of the recesses the stamper or the mould, respectively, are arranged so as to be stationary and the laser beam is guided over the stamper or the mould, respectively, in a circular track, by means of a controllable optical system.