METHOD OF MAKING COPIES OF INFORMATION TRACKS ON CARRIERS

METHODE DE PHOTOGRAPHIE DES PISTES D'ENREGISTREMENT DE SUPPORTS

English Abstract

ABSTRACT:
Photographic copying of plates having coded
video and audio information of a very fine structure.
Use is made of aromatic diazosulphide as a photosen-
sitive system in which after exposure a metal nuclei
image is produced by contact with metal salt, which
image is intensified by physical development to a
metal image having a density below D = 1.
- 13 -

Claims

PHN 8503
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. A method of making copies of information
carriers having a spiral-like information track or
a track built up from concentric circles, in which
audio and/or video information is stored in the form
of frequency- or phase-modulated signals in the form
of blocks of variable lengths which lie in a flat
plane, separated by regions of variable lengths
which likewise lie in a flat plane, characterized
in that use is made of a photosensitive material
consisting of a base layer in which a photosensitive
compound is present which is of the type which after
exposure provides a light reaction product which is
reacted with mercurous ions in the presence of mois-
ture to separate mercury which
is deposited in the form of a physically
developable metal nuclei image, which photosensitive
compound is an aromatic diazosulphide of the struc-
ture
<IMG>
wherein the benzene ring may contain one or more
substituents X and wherein R is a branched or non-
- 11 -

PHN. 8503.
branched alkyl group or aralkyl group, and N is an integer
from 0 to 5 inclusive, the resulting nuclei image being
developed to a low density above the basic density of the
carriers and below D = 1.
2. A method as claimed in Claim 1 wherein the
photosensitive compound is reacted in the presence of mois-
ture and silver ions.
3. A method as claimed in Claim 1, characterized
in that the copy is manufactured on a transparent carrier
to read in reflection against a reflective surface present.
4. A method as claimed in Claim 3, characterized
in that the copy has a reflecting metal layer.
12

Description

PHN 8503
The invention relates to a method of making
copies oE information tracks on carriers and in part--
icular of information tracks of a spiral-like struc-
ture, in which audio and/or video information is
stored in the form of frequency- or phase-modulated
signals, and which structure is built up from blocks
of variable length which lie in a flat plane separated
by areas of variable length which also lie in a flat
plane. This type of information tracks which i5 des-
cribed in British Patent Specification 1,391~541 has
a very fine structure; the length of the said blocks
in practice is of the order of ljum and the width
thereof is approximately 0.3/um.
It is known from United States Patent
Specification 3,381,085 to photographically make
copies of information tracks on which coded images
are provided in the form of a spiral-like track of
variable light transmission which has been written
; by means of a modulated electron beam. Such an
information track has a rather coarse structure.
Photographical reproduction thereof does not present
any problem.
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~9 4~ ~EIN 85Q3
Z2.6.77
It hls been found, however, that .i.nformation
tracks of` t;he lcind as described in British Patent Spe-
cification l,391,541 cannot be copied as such photo-
graphically
Light scattering during the eYposure and
the occurrence of deflection phenomena may produce
annoying back ground no:ise.
The usual photographic emulsions on the
basis of silver halide are -too coarse--grarlul.ar to
be able to reprocluce the fine detai]s of the infor-
: mation track without losses. Even emulsions of this
kind having a very small grain, the so-called Iipp-
mann emulsions, proved to be unfit for this purpose.
The occurrence of deflection phenomena
which i5 associated with the fact that the wavelength
of the light which is used for making the copy is of .
the same order of magnitude as the images to be co-
p:ied, was experienced to be very annoyi.ng in~various
systems, including sorne molecul.ar disperse ligh~-
sensitive systelns, such as material whictl contains
. an aromati.c d.iazosulpllonate and which aft;er expo-~
su:re is contacted with a solution containing me~r-
curous :ions and possi~ly also silver ions so that
physically developable mercury-or silve:r ama.1.gam
nuclei are obtained.
hpart from this it has be~n f`ound that
the di.a.70sulphonates are insuf`ficien-tly resistant

PIIN ~503
~2~6O77
to dit`fuslon so that a considerable part of the defi--
nition :if the or:igi.nal would be lost. Moreover~ it is
actually not obvious at all to photographically mal~e
copies of` informa-tion tracks of` the above-mentioned
kind, as obtained, f'or example, according to the
method described in British Patent Speci~ication
1,447,a66. According to this method, a photolac;luer
is provided on an information carrier of` clisc-form
and, by rotation of the disc relatlve to a puncti--
~orm source of radi.ati.on, in particu:l.ar a beam of
radiation provided by a :Laser, is inte~ i.ttently e~
posed and not exposed during -variable times corres-
ponding to the information, the photolacquer is
developed and the desired informa-tion track i9 e tch-
ed.
The information track thus COllSiStS of a
relief image. When a copy is to be made herefrom
photographically, a.n image in the carrier is ob~
tained wh:ioh e~tends substaIltially througrhollt the
thiclcness o:~ the carri.er. It is not obvious at all
that the whole video and audio information wou:l.d 'be
transmit-ted completely by th:is.
lt has surprisingly been found no-~S llo1r-
ever, that excellent copies of in~orn~ation carriers
having a sp.iral~like informatioll track or a track
built up f'rom concentric circles in ~rhich aud~o
and/or video information is stored in the form of
.

4~i
PHN. 8503.
frequency- or phase-modulated signals in the form of blocks
of variable lengths which lle in a flat plane, separated by
regions of variable lengths which also lie in a flat plane
are obtained according to the invention by means of the
photographic system known from British Patent Specifica-tion
1,227,116. In this system use is made of photosensitive
material consisting of a base layer in which a photosensi-
tive compound is present which is of the type which after
exposure provides a light reaction produc-t which is capable
of reacting wi~h mercurous ions in the presence of moisture
and preferably also in the presence of silver ions while
separating mercury or silver amalgam which is deposited in
the form of a physically developable metal nuclei image,
which photosensitive compound is an aromatic diazosulphide
of the structure
~ - N = N - S - R,
Xn
wherein the benzene ring may contain one or more substituents
X and wherein R .is a branched or non-branched alkyl group or
aralkyl group, the resulting nuclei image being developed to
a density below D - 1 above the basic density of the carrier.
Reference should be made to Encyclopedia of Chemical Techno-
logy -- E.G. Kirk-Other, Interscience Publishers, 2nd Edition,
1968, Volume 15, pages 367-371 - see especially Fiyure 3.

9 ~5~ Pll~ 03
22.6077
By thus developing to a comparati.vely low
dens:ity, -the above--men.tioIIecl i.nterfering deflect-Lon
images are sllppressed. lt is surprising in itsel,~
-that images havi,ng SllCh unusual lo~ densities are
capable of comprising the full information.
In copies o~tained according to the inven-
-tion it i,s advantageous to read thern in reflection
against a reflecting surface presentr The unblacken'~
ed parts of the inforrnatioll carrier will ref:lect
the li.ght substant:ially unat-tenuatedly, ~hile the
image parts absorb twice: once for the inci.dent
light and once for the reflected light,
For this pUrpoSQ~ the copy may preferably
be provided with a reflect:ing metal layer~ for exam-
ple a vapour-deposited alun1inium layer.
The invention will now be descr~bed with
reference to a few exampl~s: ,
ple 1
Plates of polymethylmethacrylate hav:lng
a diameter of 31~0 mm and a thicl~ness of 1 mm are
c:Leaned and then provided with a layer o:C cellul.ose
acetobutyrate. For this purpose a 7 . 5% solui;ion of
this mater.ial in the qualit)r Tenite II of ~astman
Kodak in a mixture of solvents of methylglycol--
ace-tate-ethanol in a volume ratio of 8:2 is dis-
tributed over tlle .surface by mecLns o:f centrifugingr
at a. speed of' 2'75 rpm ~or 1 minute. The layer is

94S~
PHN ~53
22.6,77
dried in the horizontal pos:ition for 1 hour at 70~
in a furnace havi.ng forced ai.r circulation, 'L'he
dried laye.r has a thickness of 4/um. 'rhe cellulose
acetobutyrate layer is made hydrophilic by saponi-
ficatioll and then m,ade photosensitive by means of
the fo].lowing treatment s-teps:
a) soaking for 5 mimltes in a 6 . 5~o solution of 20C
of KOH in a methanol-wa-ter mi~ture in a ~olume
ratio ~,:2.
b) soaking for 1 minute in a 9% solution of lactic
acid in a methanol-water mixture ~8:2)
, c) soalcing for 1 minute in a 1% so].ution in de-
~t~ ~ a~
rninerali~ed water of "Lissapol N",~a conderlsa-
tion product of ethylelle o~ide with al.kyl phs-
nols;
d) rinsing for 5 minutes in running demineralized
water ' '
e) 3 x soaking for 1 minute i.n propanol--1
f) soaking for 3 minutes in a 0.1 molar so].ut:ion
of 3.5 dichloro~ dir(Ie-thylanlinob~n~eIle diazo
tertiarybutyls1ll.phide in propanol-1,
after ~h:ich the a.dh.ering liquid is flung away ~`or
'I minuto at a speed of 1000 rpm. The thickness of
the result:ing photosen~s:itiv~ layer is 2/um. The
2~ mate-rial :is stored in a nitrogen atmosphere. The
e~posu:re is carried out by nIeans of a high pres-
sure mercury lamp. For tha-t purpose, a photosen3iti~,7e
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,
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45~
PIIN ~503
22.~.77
plate in a cassette i.s brough-t in very ciose contact
~:ith the information ca3r:ier to be copied con~istlng
o~ a glass plate having a chromiurn layer in ~hlch
the video and audio inforrnation is recorded. The
exposure is carried out with a 125 1~ HPR lamp ~or
40 seconds at a distance of 1 metre. In the light
path a correction filter with a density D = 1 is
placed so as to obtain a homogeIleous exposure,
A.fter t:he e~posure the pla-te is Icept im~
mersed in a nuclei-:form:ing bath for 2 seconds,
; which bath conta;.ns per litre
0~0~5 rnol (Hg2(N03)2
0.025 mol AgN03 and
0.01 mol HN03,
.
is then rinsed in denlineralized ~ater for 4 seconds
and developed for 45 seconds in a developer ~hich
is kept at 20C and has the corriposition per litre:
0.0~ mol ferrou.s ammoni.um slllphate
0.01 n1o.L f;erric nitrate
0.01 mol silver ni.trate
0.03 mol citr:i.c acid
(tl~ac~le rn q~K )
O, 02% I'Armac 1 2D~'A~ncl
0.02t~ "Lisaapol. N",
rinsed in deminerali.zed ~ater f OI` 60 seco~lds,
in propanol-1 for 60 seconcl.s a.nd fillally dried in
a dust-f`ree cupboard. The achi.e~-ed density is
S
~ ~ .

PM~ ~0,
22.6.7
n - o.3.
On the -irnage si.clc Or tlle cop~r an alurninium
layer i.5 vapour-deposited and the pllotographic ima~e
is reas as a reflection image from -the rear side.
The quality of the image and the sound cannot be
disti.nguished frorll tha-t of the original.
"Armac 12D" is an anionogenic wetting
: agent ~rhich consists of dodecylamine acetate for- ap-
pro~in1ate].y 90%~ of tetradecyla.mille acetate ~or ap-
pro~imately 9,~ and of acetates of hlgher alkyl-
ami.nes ~or the rernainder.
E~arnE~ 2
. Gla.ss plates having a diarneter o~ 340 mm
: ancl a thicl~ness o:~ 5 mm are cleaned and then pro-
: 15 vided with a layer of` chromium, approxiMately 45 ~
thick, by vapour deposition. Hereon an.appro~i.mate-
: ly 25 ~ thick Ti.02 layer is provicled by dipping the
plates in a 2, 5% solution of titane acet~rl acetol1ate
in propanol-2, dra1~ingr them up slowly and then heat-
ing them at 200C. The plates a.re co~ered ~ith a
oellulose-acetobutyrate layer in the manner as
clescribed in the prececling example, made photo
sensitive, nucleated and developed. The e~pvsure
- time and/or developmellt t:ime are chosen to be one
third to one quarter ~horter becau.se thc chrolnium
layc-r a:Lready present dllring the e~posure may give
rise to noise. The dansity cannot be measured clirec.t~
~ ' _ g _
~ .
: `:

~L9~
P~IN .X503
22 , G . 7 7
ly due to the preserl.ce O:r -t,he chrorni.wm l.ayer; it
is esti.matecl to have a va:l-7.e D _ 0.2. The copy made
in thi.s manner can be read direc-tly in re~lection
from the front side. The quali.ty of` the small image
and the sound callnot be distinguished f`rom th.a-t of
the original,
According to this method it is possible to
provide a plate on both sides ~ith an information
track.
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