Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The present invention relates -to a dry process,
high sensitivity imaging film, and to a method of pro-
ducing such a film. In its more speci:Eic aspects, the
present invention relates -to improvements in the dis-
persion imaging film disclosed in copending Canadian ap-
plications Serial No. 309,184, filed August 11, 1978,
entitled "Method of High Sensitiyity Imaging and Imaging
Film Therefore," (now Canadian Patent No. 1,112,932, issued
November 21, 1981) and Serial No. 359,425~ filed September
2, 1980, entitled "Imaging Film With Improved PassivatIng
Layers".
The dry process, hi~h sensiti~ity imagIng film
disclosed in the first-mentioned application~ that i~s/
Serial No. 309,184~ includes a solid, high optical den-
sity and substantially opaque layer o$ dispersi~on imaging
material deposited
.i~,
mab/i~
~l ~
on a substrate. The layer of dispersion imaging material comprises
a plurality of separate layers of different and substantially
mutually insoluble components having relatively high melting points
~and relatively low melting point eutectics, and interfaces between
said layers having relatively low melting points. Energy is
applied to the layer of dispersion imaging material, in an amount
above a certain critical value sufficient to increase the absorbed I
energy in the dispersion imaging material above a certain critical !
temperature value related to the relatively low melting points
of the interfaces, to substantially melt the low melting point
interfaces and incorporate the different and s~stantially
Imutually insoluble components of the separate layers into the
Isubstantially molten interfaces and, hence, to change the layer
to a substantially fluid state in which the surface tension of
the dispersion imaging material acts to cause the substantially
'opaque layer, where subject to said energy, to disperse, or
¦roll back~ and change to a discontinuous layer compxising openings
~and deformed material which are frozen in place following the
jlapplication of energy and through which openings light can pass
¦for decreasing the optical density thereat. The film can
¦provide high contrast imaging or continuous tone or gray scale
imaging. A passivation layer may be deposited on the substrate
;~of the film before the layer of dispersion imaging material is
deposited thereon, and a second passivation layer may be deposited !
on the layer of dispersion imaging material. The passivation
layers on each side of the layer of dispersion imaging material
act to effectively prevent or substantially reduce oxidation
of the dispersion imaging material and, hence, possible deteriora
tion of the op-tical density of the layer of dispersion imaging
Il -3
.material over a period of time. The imaging film of said appli-
'cation preferably also is provided with a protective overcoat layer
on .he side thereo~ opposite to tha-t on which the substrate of
the imaging film is located~ I
,I The high sensitivity imaging film disclosed in
'copending application Serial No. 359,425, like the imaging film
of application Serial No. 309,184, comprises a high optical
~density and su~stantially opaque layer of a dispersion imaging
.material carried on a substrate. The dispersion imaging mat,erial
layer may be comprised of a single, homogeneous region ormed
of a given element, alloy, or composition, or contiguous layered
Iregions of different elements, alloys, or compositions comprising
in totality a single image for~ing layer. As the title of
Serial No. 359,425 indicates, the imaging film disclosed therein
.incorporates improved passivation layers, which, as in the
'.limaging film of Serial No.`30q,184, are positioned on each
j!side o~ the dispexsion imaging material layer. The imaging
ifilm can provide high contrast imaging or continuous tOne or
gray scale imaging, and as i~ the case of the imaging film of
¦said earlier ~iled appli~catiQn, p.re~:erabl~:als~ ;s provi~ded
with a protective overcoat layer.
In accordance with the present invention, a dry
process imaging film ~as been evolved which can be imaged at
mi~imal applied energy intensity levels thereby proviaing an
imaging film having a sensitivity heretorore unattainable with
prior dry process imaging films. ~hus, merely by way o~ illus-
tration, the.imaging film of this invention is upwards of a
hundred fold more sensitive than the high sensitivity dry process
1, .
i, - 3 -
., .
,'1 i
~, i
-4
i imaging films disclosed in the aforementioned two copending appli-
cations. Moreover, and quite unexpectedly, the greatly enhanced
sensitivity achieved with the imaging film of the present
invention in no way adversely affects the continuous tone
properties of the high sensitivity films disclosed in the
aforementioned copending applications. In fact, the continuous
tone properties of the imaging film of this invention, surprisingly,
are extended over a broader range of gray scales than is possible I
with the high sensitivity imaging films of said copending appli- !
cations. Furthermore, the greatly enhanced sensitivity of the
imaging film of the present invention does not in any way alter
the high contrast properties of the films disclosed in s~id
appliations. Therefore, the imaging film can e~fectively serve
¦las a high contrast imaging film having a high gamma or as a
¦~continuous tone or gray scale imaging film having a low gamma.
The imaging film is equally adaptable to imaging by a beam of
~¦radiant energy such as a laser beant of coherent energy ~hich
;~serial1y scans the film and which may be intensity modulated
for determining the amount of dispersion or change to a dis-
¦continuous condi~ion of the dispersion image forming material
¦layer, or by noncoherent radiant energy afforded by, for example,
¦!a Xenon lamp or flash bulb which is applied through an imagingmask having ~ full format continuous tone maging pattern.
The latter manner of continuous tone or gray scale imaging is
particularly applicable to and has great significance in several
respects in dry process imaging apparatus for producing microform
records from light reflecting hard copy, as disclosed in U.S.
Pa~ent No. 3,966,317 and U.S. Patent No. 4,123,157, wherein the
light reflecting hard copy is microimaged as a transparency
on an intermediate mask film and wherein the microimaged trans-
parency of the mask film is reproduced on the layer of dispersion I
'I i
i s
i! imaging material by a short pulse of radiant or electromagnetic
energy. The uniquely high sensitivity of the imaging film allows ¦
Ifor greater tolerances in the lighting, lens system, intermediate
llmask film and flashing svstem of the apparatus disclosed in
said patents while at the same time enabling faithful and
accurate reproduction of microimages of hard copy including line
¦ drawings, printed material as well as photographs, or the like.
The imaging film of this invention lends itself to production
,and use in the form of flexible sheets or strips capable of
I being wound in rolls, thereby facilitating handling and storage
l~of the film before, during and after imaging. The imaging film,
in addition, has excellent shelf life and archival properties.
The high sensitivity imaging film of the present
l invention, in brief, comprises a layer of a dispersion imaging
¦Imaterial having a layer of a surface modifying substance in con-
¦Itact with at least one surface, and, in accordance with one
embodiment of the invention, both surfaces thereof. The surface
Illmodifying substance advantageously comprises an organic material
,¦such as an organic polymer which shows very low or poor in~er-
¦Ifacial adhesion for the dis~ersion imaging material when the
¦latter is in a substantially liquid or molten state during
imaging. In accordance with the method aspects of the in~ention,
the surface modifying substance layer is formed by vapor deposi-
tion as exemplified by glow discharge deposition, evaporation
Isputtering, or the like. The imaging film of this invention ~*herl
;desirably includes at least one,and mDst advantageously, ~wo passi- ¦
vation layers which act to shield the dispersion imaginy
material from reactive elements, such as oYygen, in the atmosphere.
The imaging film also further desirably includes a subs~te and a pro-
~tective overlayer on the side o~ the film opFosi-e to that on which-the s~lb-
strate is located. me substrate and the protective overlayer preferably c ~
prise flexible plastic materials which, in cooperation with the other
- 5 -
l, l
~ ;
,~layers of the imaging film, impart the desired flexibility to
the film.
The foregoing, and other features and advantages
of the invention will become apparent to those skilled in the
art upon reference to the accompanying specification, claims
and drawings, in which:
Fig. 1 is a greatly enlarged sectional and
~stylized view th~ough an embodiment of the high sensitivity
imaging film of this invention before imaging;
¦ Fig. 2 is a sectional view similar to Fig. 1
,lillustrating the imaging film when it is imaged by the appli
¦Ication of relatively low energy above a critical value and
¦~having a relatively high optical density to provide a continuous
lltone or gray scale image on the film;
¦~ Fig. 3 is a sectional view similar to Fig. 2
illustrating the film when it has been subject to a greater
~lamount of energy above the critical value than was applied in
¦¦the case of Fig. 2 to provide a continuous tone or gray scale
¦image on the fllm;
Fig. 4 is a sectional view similar to Figs. 2 and
~3 illustrating the imaging film o~ Fig. 1 when subjected to a
6 --
', .
,l ~156869
I
-6a
I,,still greater amount of energy and providing a high contrast
"image on the film;
Fig. 5 is a greatly enlarged sectional and
,stylized view through another embodiment of the high sensitivity
imaginy film of this invention showing the surface modifying
substance layer on the side of the dispersion imaging material
l~layer opposite to the sida on which it is positioned in the
t embodiment shown in Figs. 1, 2 and 3;
.
Fig. 6 is a greatly enlarged sectional and
stylized view through yet another embodiment of the high
,lsensitivity imaging film having a surface modifying substance
layer on each side of the dispersion imagi~g material layer;
Fig. 7 i9 a diagram~atic illustration of a
system for the production of the imaging film in a continuous
web process; and
Fig. 8 is an enlarged schematic view of the
¦glow discharge disposition station of the system shown in
Fig. 7.
,. I
'. I
- 6a -
i.
., ,
~ 7
Referring, now, to ~igs. 1, 5 and 6, the e~)diments
~of the high sensitivity imaging film illustrated and designated
by reference numeral 10 in Fig. 1, reference numeral 12 in
Fig. 5 and reference numeral 14 in Fig. 6, each includes a
substrate 1~ which is preferably transparent. ~ile the ~ubst~ate¦
¦~16 may be formed from substantially any substrate material, it
~is most advantageously formed from a flexible, transparent
plastic sheet material. Exemplary of suitable plastic sheet
,materials are those based upon polyesters, polyamides, cellulose
acetates, polyethylenes, and polypropylenes, to mention a few.
An especially preferred plastic sheet ma~erial is a polyester,
namely,polyethylene terephthalate, known as Meline.Y type O
llmicrofilm grade sold by ICI of America~ The thickness of the
¦~substrate 16 desirabl~ is in the range of about 2 to about 10
mils, preferably from about 3 or 4 to about 7 mLls.
¦ The embodiments of the imaging films 10, 12 and
¦14, as shown, also include a dispersion imaging material layer
18, at lea~t one) and Ln certain instances~ two (see Fig. 6) sur
face modifying s~stance layers ~0 and two passivation layers 22.
The nature of the layers 18, 20 and 22 will be discussed in detail !
below. The films 10, 12 and 14 further desirably are provided
with a suhstantially transparent, protéctive overlayer 24. The
overlayer 24 may comprise a polymeric resin material such as
polyurethane~ polyvinylidine chloride or a silicone resin. The
polyurethane product sold under the trade mark ~'~STANE No. 571S"
¦(B.F. Goodrich Company), and the polyvinylidine chloride product
~available commercially under the trade mark "SARAN" (Dow
Chemical Company) form excellent overlayers for the imaging
film. The thickness of the overlayer 24 can range from about
., I
' 7
,. i
* trade mark
~iLS6~
0.1 to about 3 microns, preferably from about 0.5 to about
1 micron. It can be applied to the imaging fi~lm in any
of various ways, including spin coating, roller coating,
spraying, vacuum deposition, or the like.
The dispersion imaging material layer 18 of the
imaging films 10, 12 and 14 may comprise low melting
point amorphous semiconductors ! exemplified by the chalco-
genide elements, except oxy~en, and compositions containIng
them, as disclosed in V.S. Patent Nos. 4~000!334 and
4,267,261. These include the materials which are known
as memory materials and which are characteri~zed by thei~r
ability to physically change from one condition to another
- under the effect of ener~y. These materials may be used
in their amorphous or in thei~r crystalli~ne form. Speci~fi~c
examples of such material$ are telluri~um and yar~ous com-
positions containin~ tellurium, and other chalcogeni`des
- (parts being by wei~ht) such as, ~or example, a compositi~on
92.5 atomic parts tellur~ium, 2,5 at~:mic parts ~ermani~um~
2.5 parts silicon and 2.5 atomi~c parts arseni~c; a com-
position of 95 atomic parts tellurium and 5 atomic parts
silicon; a composition of 90 atomic parts tellurium, 5
atomic parts germanium, 3 atomic parts silicon and 2
atomic parts antimony, to mention a few. The layer 18
also may comprise low melting point metals or metal alloys
such as those disclosed in U.S. Patent Nos. 4,082,861 and
4,137,078, and the aforementioned copending application
Serial No. 309,184. Exemplary of such materials are bis-
muth, alloys of bismuth with tin and lead, tiered layers
comprising bismuth and its oxide, and tiered layers com~
prising bismuth, zinc! lead~ tin, cadmium and indium, for
example, which form low melting point eutectics at their
- 8 -
mab/~
ll -9
! interfaces In this connection, it should be understood that in
¦Ireferring herein to a layer of dispersion imaging material, the
l! term "layer" is intended to encompass a layer of dispersion
imaging material which is comprised of one homogeneous region of
a yiven element or composition, or con~iguous tiered regions
o~ different elements or compositions which form in totality a
¦! single dispersion imaging material layer. The thickness of the
l layer 18 advantageously is such as to provide an optical density
,jof from about 1 to about 5, preferably from about 1.2 to about
3, in the completed-imaging film depending upon the opacity
l'desired. Generally speaking, the optimum objectives o the
,¦invention are achieved with dispersion imaging maferial layer
¦¦thicknesses of the order of about 200 Angstroms to about 2000
¦Angstroms, with a thickness in the range of about 250 Angstroms
¦to about 1000 Angstroms being preferred. Deposition of the
layer 18 may be accomplished by sputtering~ vacuum deposition,
or the like.
The layer, or layers~ ~0 ofsurface m~ai~yin~ subs~ce
¦comprising the imaging films 10, 12 and 14, as illustrated, are
¦in direct contact with the layer 18 of dispersion imaging
material~ As indicated hereinabove, the presence of the
layer 20, whether it-is in contact with one or both s~rfaces
of the layer 18 has the surprising and unexpected effect of
increasing, by upwaras of a hundred times, the sensitivity of the '
!l imaging film of this invention over high sensitivity films such
as those disclosed in the aforementioned copending applications
Serial Nos 309,184 and 35~,425. The layer 20 preferably is
formed of an organic, or organic-like, material capable, upon
being vapor deposited in a manner to place it in contact with
l _ 9 _
. ~ 1
~6~
li l
1,1
-10
one or both of the surfaces of the layer 18 of dispersion imaging
,material, of forming a thin, flexible and transparent layer
on said surface or surfaces. The formed l~yer 20 is characterized
by the very low or poor interfacial adhesion between the material
of the layer 20 and the dispersion imaging material of the layer 1
18 when the material of the layer l. is in a substantially li~uid ;
or melted state during imaging, and, concomitantly, by the
apparent ability of the layer 20 to enhance~ augment and increase
the roll back or dispersion capabilities of the layer 18 when
the material thereof is in said state to provide, as indicated
abover an imaging film having improved continuous tone and high
contrast properties. These factors, coupled with the substantial
absence of electrostatic charges at the interface of the layers
18 and 20, enable dispersion or roll back of the dispersion
imaging material of the layer 18 to be achieved with substantially !
less intensity of applied energy than ~as heretofore possible
with dry process imaging films. In addition to the aforementioned
desiderata, the layer 20 should be chemically inert with respect
to the dispexsion imaging materi.al layer, and possess properties
f adhesion with respect to the passivation layers consistent
llwith the structural and imaging requirements of the imaging film.
,,Also for cost effective production it is desirable that the
Illayer 20 be capable of rapid deposition with standard vapor
.ideposition equipment such as glow discharge deposition,evaporation
¦sputtering, or the like, appar~tus. The. thickness of the layer
or layers 20 of the surface modifying substance need only be
sufficient to change the interfacial adhesion properties of the ,
contiguous surface of the ].ayer 18. This can be effectively
achieved with essentially monomolecular thicknesses of the
substance. In general, however, the optimum objectives of the
invention are attained with surface modifying substance layer
- 1 0 -
~ 5~
thicknesses up to about 300 ~lgstroms, preferably from about 25 to
¦labout 200, or 250, Angstroms.
¦ Exemplary of organic, or organic-like, materials
! useful in formung the layer 20 of the high sensitivity imaging film
~of this invention are polymerizable monomeric materials such as
methane, ethane, ethene, propane, propene, butane, butene, iso-
butane, isobutylfluoride, carbon tetrafluoride, carbon hexafluoxide,
ethylidene fluoride, chlorotrifluoromethane, difluorodichloromethale,
isop~opylfluoride, isopropylidene fluoride, and the like, and coFoly~erizable
~mixtures thereof. Also useful are poly~erizable organic-like ma-terials
e~emplified by monosilane, chlorosilane, methyl~onosilane, dimethylsilane,
txi1uorosilane, and the like, and copolymerizable mixtures thereof.
¦~Of the foregoing materials, fluorinated hydrocarbons, as exe~plified by carbon
tetraflt~ride, are preferred. It is noteworthy that the surface m~difying
materials usef.ul in forming the layer, or layers, 20 of the imaging film
most advantageously are gases. In this form, the m~terials are more readily
adaptable to continuous m~ss production of the imaging fi~t in a vaFor de~osi-
tion cha~ber where the various layers of the imaging film are deposited by
¦~acuum depcsition or, as in t~e case of the layer, or layers 20 by glow dis-
charge deposition, evaForation, sputtering, or the like, techniq~tes~ It
¦should be understood, however, that surface m~difying materials, especially
organic, or organic-like materials ~tich normally exist in a liquid state, but
I!which can be easily converted to a gaseous state for vapor deposition as by
¦Iglow discharge deFosition, for example, are contemplated for use in forming the
layer, or layers 20. Exemplary of such materials æe pentane, l-pentene, hexanel,
-hexene, to mention a ~ew.
The passivation layers 22 which comprise the imaging
¦ film of this invention can be formed of any material capable
of effectively providing a barrier or shield for the dispersion
imaging material layer 18 to prevent or substantially limit
oxidation of the components of the layer. Specific examples
of materials which can be used to form the passivation layers are
"
!
~ ~.156~69 -12
silicon monoxide and dioxide, al~inum oxide, sermanium oxide,
tellurium oxide, tin oxide, beryllium oxide, and the like.
¦Especially preferred materials for use in forming the passivation
layers are those disclosed in the previously referred to copending
application Serial No. 359,425. The materials comprise oxides
Group IV metals. The oxides advantageously are in an
amorphous ~orm and are stabilized in this form by alloying them
ith amorphous oxides or halides of a metal or semiconductor.
¦Specific examples of compositions of this type useful in forming
~the passivation layers of the imaging film of this invention
,lare the following wherein the subscript numbers indicate the
aPproximate percentage of the crucible mixture by weight of the
jcompounds involved-
(GeO~) 70(Al23) lo(B23)~l0( ).l0~GeO2) 80(Al23).lo(PbO) l0
~GeO2~ 85(Ti2) lo(Al23).05
(GeO2) 80(Al~03)~05(PbO~o05(K2)~l0
(GeO2) 80~ 03)~lo~PbO).o5(~2)uos
~GeO2~ ~o(Al2O3) l0 (Tio~ O (PbO) ns (~201~S
(Ge2) 75(Al2o3)~lo(Tio2)~o5(Mgo)~o5(K2ol~o5
he passivati~n layers 22 must be continuous an~ essentially free
~f holes or voids. In addltion, they must be flexible and not
susceptible to cracking or fracturing when tne imaging film is
wound in a roll. Experience has shown that the required flexi-
pility is attained with passivation layer thicknesses ranging
from about 75 to about 450 Anystroms r with a thickness in the
range of from abou-t l00 to about 200 Angstxoms being especially
preferred. The passivation layers are most effectively deposited
on the film by vapor deposition using an election beam source.
- 12 -
ll l
j,
l! l
!1 -13
While in the preferred embodiments of the high sensiti~ity film
¦Ishown~ separate passivation layers 22 are included as an integral
¦Icomponent of the film, it should be understood that the layers
22 may not be necessary in those instances where the substrate
1116 and the protective overlayer 24, for example, are inherently
jlcapable of providing a barrier or shield to prevent or substan- ¦
I tially limit oxidation of the dispersion imaging material.
As stated hereinabove, the various layers comprisingl
the imaging film most advantageously are deposited by vapor deposi-
tion techniques. The dispersion imaging material layer 18 and the'
~passivation layers 22 desirably are deposited by vacuum deposition,
including resistance heating or electron beam deposition. The
layer, or layers 20 of surface modifying substance, on the other
l! hand, as indicated above, preferab:Ly are deposited by glow dis- I
¦Icharge, evaporation, sputtering, or the like, techniques. By way ¦
llof illustration, and with specific reference to Figs. 7 and 8 of
¦¦the drawings, the deposition o~ the dispersion imaging film layer
Il 18, the surface modifying substance layer, or layers 20 and the
¦ passivation layers 22 may be carried out in a continuous web
¦Iprocess. In Fig. 7, there is schematically illustrated apparatus
~for producing the imaging film of this invention by such a process.
IThe apparatus, designated generally by reference nu~eral 30,
¦jcomprises a vacuum chamber 32 having positioned therein a web
take-up spool 34, a rotatable metal drum 36 and a web take-up
spool 38 wi~ ~le substrate 16 coursing the sa~e. I~e apparatus as sh~Jn
¦1also includes a metal w~lled glow chamber 40 positioned along the periphery
o~ the metal drum 36, and a plurality of evaporation sources
represented by boats 42. The materials contained in the boats
42 may be selectively evaporated by electron beam guns (not
shown), for example, and deposited on the substrate 16 as it
is passed over the drum 36. The apparatus also preferably
- 13 -
, I ,
i
,1 .
~LlSl;~i9
includes a web position idler (not shown) arranged between the
drum 36 and the web takeup spool 38. In addition, the apparatus
lalso desirably includes a crystal rate controller (not shown)
¦which el~ctronically controls the deposition power of the
llelectron beam guns, and an optical monitor (not shown) for
¦¦monitoring the depositions of the respective layer materials on
¦the substrate 16 as to optical density. The vacuum chamber 32
jis evacuated by means o~ a vacuum pump 44 through a particle
trap 46 and a control valve 48.
Ij As best shown in Fig. 8, the glow chamber 40
¦lincludes a cathode 50 connected to an RF or DC power input
¦source, and backed by a suitable insulating material 52 to pre~ent
¦plasma discharge in undesirable regions. The metal walls of
Ithe chamber 40 are connected to an electrical ground (not
¦shown). The materials to be deposited by glow discharge deposi- ¦
tion are supplied to the chamber 40 through one or more conduits
154- A pressure gauge 56 is provided to indicate the vacuum
¦pressure in the glow chamber 40 and is used in connection with
the control of the vacuum pump 44. The exhausted gas from the
chamber 40 escapes into the vacuum chamber 32 through the
restricted openings or clearance spaces 58 between the walls
of the chamber 40 and the surface of the substrate 16 supported
on the drum 36. The drum 36 is attached to an electrical
ground connection (not shown) and serves as the ground electrode
¦Ifor the glow discharge deposition of the surface modifying substance
layer, or layers 20. The rotatable drum 36 may be heated or
cooled by means of hot or cold water or other fluid which can
I ' ~
- 14 -
l l l
~l i
be circulated through the drum with rotating fluid feed troughs
I(no-t shown) whlch are in communication with the surrounding
atmosphere outside of the chamber 32. The temperatuxe of the
drum is measured and controlled by measuring and controlling the
temperature of the heat-exchan~e fluid from outside of the
chamber 32.
In utilizing the apparatus schematically illustrated¦
in Figs. 7 and 8 to produce the high sensitivity film of this
invention, the vacuum chamber 32 is evacuated by means of the
~ pump 44 to less than about 5 x 10 5 Torr ana the substrate 16
Ilis paid off the payoff spool 34 over the water cooled drum 36
to the takeup spool 38, and reversed back onto the payoff
spool 34 at a speed of about 10 ft/min for the purpose of first
outgassing the polyester substrate 16. The substrate 16 is
then advanced from the payoff spool 34 and has deposited
,Ithereon by means of electron beam guns a first passivation
¦llayer of about 150 Angstro~s of GeO2, for example, contained
¦¦in one of the boats 42, at a rate of about 60 Angstroms/sec and
¦a web speed of about 10 ft/min. The deposition rate is con-
¦trolled by using a crystal rate controller (not shown) which
electronically controls the deposition power o~ the electron
Ibeam guns. The passivation layer coated substrate is then
¦¦returned to the web payoff spool 34 for the next deposition
step. About a 400 Angstrom layer of bismuth and tin, for
example, is then co-evaporated on the passivation layer coated
substrate, as it is again ad~anced toward the boats 42, from
another set of electron beam guns at a rate of about 150
Angstroms/sec, with a web speed of about 10 ft/min. The
deposition rate is again controlled by the crystal rate controller,
j - 15 -
A:~l 56~i9
-16
l l l
and the optical density of the film is monitored by an optical
l!monitor (not shown) during the run. The substrate, with the
IIGeO2 passivation layer and the co-deposited bismuth-tin dispersion
¦'imaging material layer is again returned to the web payoff spool
34 for deposition of a layer of surface m~di~ing suhstance on the
dispersion imaging material layer.
Il As indicated, the space in the glow chamber 40
between the cathode 50 and the electrically grounded metal
surface of the drum 36 provides for a glow discharge condltion
therebetween so as to produce a plasma therebetween. The
ll~acuum chamber 32 is first pumped down by means of the pump ~4
¦,to a pressure of about 20 mtorr prior to deposition of the
jsurface modifying substance layer. A polymerizable gas comprised of carbo~.tetra~
,fluoride (CF4), for example, is fed into the glow chamber 40
jthrough one or both of the conduits 54. The gas is fed at a
constant ratio of about 10-50 sec/min. into the glow chamber
40, the pressure of which is maintained within the range of
¦about 0.1 to 2, preferably 0.5 torr. The partial pressure in the
¦glow chamber 40 and the gas introduced therein provide an
¦atmosphere thereîn which contains such gas. A plasma is generated
¦in said atmosphere over the coated substrate 16 using a radio
¦fre~uency power, for example, of about 1000 ~Jatts, operating at
about 12 to about 15, preferably about 13.5 ~Iz. A layer of
about 200 Angstroms of a polymer based upon the carbon tetrafluoridje
is deposited on the layer of the dispersion imaging material
using a deposition rate of about 10 to about 50, preferably
about 30 Angstroms per second.
16 -
1~56~9 -17
¦l Following the glow discharge deposition of the
surface modifying substance layer, a second layer of a passivationl
Illayer comprising GeO2, for example, is deposited on the surface
¦Imodifying substance layer utilizing the same procedure employed
¦¦to deposit the first passivation layer. It should be understood
~Ithat the passivation layers may be formed of the same or different
materials. Thus, the second, or last to be deposited passivation
layer may comprise SiO, for example. Similarly, in those
instances where a surface modifying substance layer is provided
on each surface of the dispersion imaging material layer as
shown in Fig. 6, each of the layers 20 of the suxface modifying
substance may be formed from the same surface modifying material, i
or they each may be formed of a different surface modifying
Illmaterial. After deposition of the second passivation layer,
,l~the web is then removed from the vacuum chamber and is roller
~coated with a polymer overcoat having a thicknness of about 500
to about 6000 Angstroms. Care is taken in the payoff and
Itakeup spools, both during evaporation depositions and overcoating
¦ to control the web tension to avoid scratching, telescoping and
so forth of the imaging film.
Referring again, now, to Figs. 1-6 of the drawings,
imaging films 10, 12 and 16 may be imaged by energy, such as,
¦Ifor example, non-coherent radiant energy from a Xenon lamp or
¦la flashbulb or the like through an imaging mask 26. The imaging
mask 26 can control the amount of non~coherent radiant energy
- 17 -
,
, I
, !
5~
i !
passing therethrough and the amount of energy absorbed in the
~dispersion imaging material layer 18 and, therefore, can control
the amount of dispersion of the dispersion imaging material and
the optical density thereof where imaged.
In accordance with this invention, as expressed
~'above, d~y process, e~ceptionally high sensitivity imaging is
provided, including high contrast imaging or continuous tone or
gray scale imaging, depending upon the nature of the high
,sensitivity imaging film~ In Fig. 1, the portion 26a of the
l~imaging mask 26 has a sufficiently high optical density to limit
the amount or intensity of the energy, as shown by the arrows,
Iapplied therethrough to the layer 18 of dispersion imaging
¦Imaterial~ so that the absorbed ene:rgy in the material is not
¦¦increased above the aforesaid certain critical value. As a
result, the material is not changed to a substa~tially fluid
llstate ~nd the layer 18 of dispersion imaging material remains
¦¦in its solid, high optical density and substantially opaque
¦icondition. There are no openings in the layer 18 through which
light can pass, the layer being substantially opaque and ha~ing
an optical density of substantially 1.0 to 1.5 or the like, for
example. This stage of imaging is applicable to bo-th the high
¦contrast and the continuous -tone or gray scale imaging films
Iproduced in accordance with the teachings of the present in~ention.
¦¦ In Fig. 2, the portion 26b of the imaging mask 26
has a lower optical density to allow more radiant energy r as
shown by the arrows, to pass through and be applied to the layer
18 of dispersion imaging material. Here, the intensity of the
applied energy is such that the absorbed energy in the layer 18
is jus~ above the aforesaid certain critical value. The layer
i - 18 -
:Lll5661~ 1
I
ii -19
18 of dispersion imaging material is changea by such energy to a
isubstantially fluid state in which the surface tension of the
,material causes the material to disperse and change to a
Idiscontinuous film having openings 18a and deformed material 18b
which are frozen in place following said application of energy
and through which openings 18a light can pass. In the case
of the continuous tone or gray scale imaging, the dispersion
imaging material is deformed only a small amount, as indicated
,at 18b to provide only small area openings 18a in the layer 18,
`ilthere being only a small amount of roll back of the deormed
material 18b from the openings 18a. The transmissivity of the
film is low, but mor~ than -that of the substantially opaque
undisPersed films 10, 12 and 14 shown in Figs. 5 and 6. Thus,
Ithe optical density of the film, where subject to such application ,l
¦¦of energy, is decreased a small amount. The area of the substan- ¦
¦tially opaque deformed material 18b is extremely large while the
area of the openings 18a is extremely small.
¦ In Fig. 3, the portion 26c of the imaging mask
¦26 has a lower optical density to allow still more radia~lt
¦energy, as shown by the arrows, to pass therethrough and be
¦applied to the layer 18 of the dispersion imaging material. The
¦lintensity of the applied energy is such that the absorbed energy
¦in the layer 18 is considerably above the aforesaid certain
critical value. Because of the increased intensity of the
~'lapplied energy, the dispersion imaging material is deformed
a greater extent as indicated at 18b to provide larger area
openings 18a in the layer 18, there being a larger amount of
roll back of the deformed material 18c from the openings 18a.
The transmissivity of the film is thus increased, the optical
.
~1 !
-20
density thereof decreased a greater amount.
In Fig. 4, the portion 26d of the imaging mask 26
has a still lesser optlcal density to allow still more radiant
,energy, as shown by the arrows, to pass therethrough and be
applied to the layer 18 of dispersion imaging material. Here,
Ithe intensity of the applied energy is such that the absorbed
¦lenergy in the film is still more above the aforesaid certain
llcritical value, substantially a maximum value. Because of this
,'further increased intensity of the applied energy, the dispersion
limaging material is deformed a greater extent to small spaced
,ljglobules 18c and the openings 18a are increased to form sub- !
stantially free space between the globules, there being a larger
roll back of the deformed material 18c from the openinys 18a.
~The transmissi~ity of the film is thus increased to a maximum and ¦
the optical density theresf decreased to aminimum.
- As distinguished from the continuous tone or
gray scale imaging having the intermediate steps illustrated
in Figs. 2 and 3, in the high contrast imaging, upon the formation;
of the openings 18a and the deformed material 18c, there is a
subs~antial instantaneous and complete roll back of the imaging
Imaterial to the discontinuous film condition illustrated in Fig. 4.
1~ The embodiments 12 and 14 of the imaging film
~illustrated in Figs. 5 and 6 differ from the embodiment of the
,¦film 10 shown in Figs. 1-4 in that thesurface modi~ying substance
layer 20 in the imaging film 12 is positioned on the surface of
the dispersion imaging material layer 18 opposite to the surface
on which i-t is positioned in the film 10, while in the film 14,
a layer 20 of surface modifying substance is positioned on, or in
- 20 -
, .
1, .
~L~561~9
-21
~contact with, each surface of the layer 18.
The energy employed to image the film of the present
Ilinvention may comprise various forms of energy. Thus, the
I energy may comprise Joule heat energy applied to the film by
~means of~ for example, direct electrical heating, electrically
'energized heating means, orthe like, and absorbed in the film.
The intensity of the applied Joule heat energy above the certain
critical value may determine the amount of dispersion or change
l,of the film to the discontinuous film for continuous tone imaging,
¦l~as discussed above. The heating means may include a single
heating point which serially scans the film and which is intensity
modulated, or it may comprise an advanceable matrix of heating
~¦points which are intensity modulated, for full format imagin~ of
the film. In both cases continuous tone imaging may be obtained.
IThe applied energy may also comprise a beam of radiant energy,
!,such as, a laser beam of coherent energy or the like, which
serially scans the film and which may be intensity modulated
for determining the amount of dispersion or change to the dis-
continuous film and providing continuous tone or gray scale
imaging.
I This applied energy may also be noncoherent
¦radiant energy, afforded by, for example, a Xenon lamp or flash
¦bulb or the like, which is applied through an imaging mask such asl
Ithe mask 26 which may have a full format continuous tone imaging
¦pattern including portions of continuously differinytransmissivity
¦Ifor the applied energy, to the substantially opaque film of dispersion
imaging material substantially evenly in a full format pattern
corresponding to the full format continuous tone imaying pattern
of the imaging mask and having areas of different intensities of
- 21 -
~1 1
!
5~
Il -22
¦, the applied energy above the certain critical value to provlde at
¦~ one time in the substantially opaque film of dispersion imaging
¦~ material a stable finished full format image pattern of dis-
continuous film corresponding to the full format continuous tone
,I pattern o~ the applied energy. In this instance the energy
I is pre~erably~applied as a short pulse of said energy.
As expressed above, this invention is principally
i directed to a high sensitivity imaging film requiring only a
'I!minimum amount of applied energy to change the imaging ~ilm fxom
!~ a solid high optical density film to a discontinuous fil~ o~ i
¦~ lower optical density. In order to demonstrate the unexpected
i' and exceptionally high sensitivity of the imaging film, an
¦l imaging film is prepared in accordance with the teachings of
llthe present in~ention, and com~ared with hi~h sensi~ivity
llimaging film prepared as disclosed in the aEorementioned copending
llapplication Serial No~ 309~184O The dispersion imaging material
¦lla~er ln each case is comprised of a codeposited layer o~ I
~bismu~h and tin approximately 400 Angstroms thick. The
¦ film prepared as disclosed in the said copending application
jhas transparent passivation layers approximately 150 Angstroms
in thickness comprised of germanium oxide in contact with both
~he inner or substxate-facing side of the dispersion imaging
l material layer and the outer, or overlayer-facing side of
¦~the dispersion imaging material. The dispersion image
ilmaterial layers and the passi~ation layers are supported on a
,'transparent polyester substrate about 5 mils thick. A transparent'
overlayer about 5000 Angstroms thick and comprised of polyurethane
is applied to the upper or outer passivation layer. The ma~imum
,. :
l~ - 22 - ,
I
1 1
-23
optical denslty (0Dmax) of the film is about 1.6. The threshold
energy value (Eth) of the film is about 0O15 J/cm2; the ODmin
is akout 0.18; and the applied maximum energy value (Ema ) is
about 0.6 J/cm2.
Ii ` , I
i~! The imaging film of this invention differed fro~
the film prepared as disclosed in said copending application in
that a polymerized, transparent layer o~ carbon tetrafluoride
~,approximately 150 Angstroms in thikness is applled to the
,'upper, or non-substrate facing surface of the bismuth-tin dis-
~persion imaging material layer before the GeO2 ~assivation
~layer is deposited. The construction of the film otherwise
is the same as the ~ilm o~ the copending application. Befoxe
¦limaging the opti~al density (ODmaX~ of the film is about 1.6.
'IThe threshold energy value (Eth) of the ~ilm is about 0.002 J/cm2;¦
! the ODmin is about 0o20; and the applied energy (EmaX) for
¦obtaining maximum di:spersion is abou~ 0.008 J/cm2. Thus, it is
seen that the energy required to disperse or roll back the
dispersion imaging layer of the imaging film of the present
invention is of the order of seventy-five tlmes less than is
~required in the case of the film prepared as disclosed in co-
¦~pending application Serial ~o. 30~ 84, which film itself is
¦¦characterized by its high sensitivityO The sensitivity of ~he
¦¦imaging film o~ this invention is even greater when two layers
¦f a polymerized substance are used as illustrated in Fig. 6 of
i! the drawings.
While for purposes of illustration various forms
of -this invention have been disclosed, other forms thereof may
become apparent to those skilled in the art upon reference to
this disclosure and, therefore, this invention should be limited 1,
~only by the scope of the appended claims.
23 _
,
