Note: Descriptions are shown in the official language in which they were submitted.
20039~
Process and device for forming a resist pattern on a
cylindrical object, and an etched metal cylinder obtained
using such a resist pattern.
The invention relates in the first place to a
process for forming a resistance pattern on a cylindrical
object, comprising the application of a layer of a
material which is resistant or can be made resistant to
S a treatment agent to be used and~or the treatment condi-
tions, and the formation, using a laser beam treatment,
of a pattern of places which are freed of said material
layer, if desired followed by further treatment of the
material layer in order to make it resistant to the
treatment agent and the treatment conditions.
A resistance pat~ern in this case is generally
understood to mean a material pattern which protects the
underlying parts of a cylinder to which it is applied
against the influence of a treatment agent and/or the
conditions prevailing during a treatment.
The treatment can be, for example, the etching of
a cylinder made of metal or etchable plastic. The treat-
ment can also be the electrodeposition of metal in an
electrolysis bath.
It will be mainly etching resistance patterns
which are discussed below, but the invention i5 not
restricted thereto, as is clear from the above.
The formation of a resistance pattern on the
outside of a cylindrical object i5 known. During the
formation of an etching resistance pattern on a cylindri-
!,, ~ I cal metal object, the latter is coated with a layer of
material which is resistant or can be made resistant to
etching agent, such as a photographic lacquer or in
general an organic lacquer. The metal cylindrical object
can be, for example, a seamless metal cylindrical object
such as a copper, nickel or iron sleeve; it is also
possible to start from a cylindrical object which is
obtained by welding the ends of a metal sheet to each
other.
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For the selection of the materials to be used,
the choice of the type of laser beam treatment is impor-
tant.
If the laser beam treatment is a burning-away
process, then in principle any material which is suitable
for burning-away or vaporizing using a laser beam can be
selected for the material layer to be used.
If the laser beam treatment is a photochemical
treatment, one can opt for a material which hardens under
the influence of radiation or is soluble in a developing
fluid under the influence of radiation, in which case
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negative or positive photographic lacquer system~ are --;
used. Following such a laser beam treatment in the
carrying out of a photochemical process, a development
step also has to be carried out, in order to remove the
material layer from the places which are still soluble or
have been made soluble in a developing fluid. If neces~
sary, following any development step, or following the ~ ~ -
laser beam treatment itself, an additional treatment can ;~
be carried out in order to give the material layer the
desired etching agent resistance.
In all cases, a cylindrical metal object provided
with an etching resistance pattern which during the
subsequently carried out etching protects the places of
the cylindrical object which must not be attacked by
etching agent is obtained at the end of the treatments.
During the application of such an etching resis-
tance pattern on the outside of the cylindrical ob~ect
alone, the problem of a very considerable degree of
lateral etching is encountered if perforations have to be
formed through etching in the wall of the cylindrical
object. -
Such a strong lateral etching means that the
fineness of the perforation pattern to be applied is
greatly limited, on account of the fact that the perfora-
tions must not overlap, particularly on the inside of the ~-
cylindrical object.
The object of the present invention is to pro~uce
a process of the type mentioned in the preamble in which ~ --
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it is possible to achieve an etching resistance pattern
on both sides of a metal cylindrical object, through
which much greater fineness can be achieved in etching
through than was the case hitherto.
According to the invention, the above-mentioned
process is characterized in that the material layer is
applied to both the inside and the outside of the metal
cylindrical object, while a pattern of places from which
the material layer is removed is formed both on the
inside and on the outside, and the patterns on the inside
and the outside have a fixed, predetermined relationship
to each other.
It was found that it is possible both on the
inside and on the outside of a cylindrical metal object
to form resistance patterns such as etching resistance
patterns which can be positioned with very great accuracy
relative to each other, so that etching can take place on
two sides.
Etching on both sides means, on the one hand,
that a reduction in the lateral etching over the entire
thickness of the cylindrical object is achieved, so that
greater through etching fineness can be achieved, i.e. a
greater perforation density (holes per unit area). It is
al80 possible by etching on two sides to achieve a
greater passage (open surface per unit area) with the
same perforation density. Etching on both sides also
means a considerable shortening of the total etching
time.
It is pointed out that etching of an object on
two sides is known per se. In such known processes the
starting material is a flat, sheet-type metal material
which is provided on two sides with an etching resistance
pattern, the two patterns being positioned very accurate-
ly relative to each other. In such a case the image-
bearing photographic lacquer patterns on either side of
the sheet correspond, and come about by making use of a
pattern-forming stage by means of a photographic film
system in which the top and bottom film are positioned
accurately relative to each other within approximately 25
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micrometres.
The above-mentioned known processes give no
information concerning the possibility of applying an
etching resistance pattern on the inside and outside of
S a cylindrical metal object.
The invention also relates to a device for the
treatment with a laser beam, according to a predetermined
pattern, of a layer of a material situated on the surface
of a metal cylindrical object, at least comprising a
clamping device for the rotatable mounting of the cylind-
rical object, laser beam forming means, laser beam
deflection and guide means, and electronic measuring and
control systems for the regulation and control of the
laser beam treatment. - ;~
Such a device is according to the invention
characterized in that the device has means for accom-
modating the end parts of a cylindrical object to be `
treated while leaving free the inside thereof, and in
that it is provided with means for the formation of two
laser beams, and guide means are present to feed the two
beams to two beam focusing elements which are disposed ~ -
opposite the outside and inside of the cylindrical
object, and provision is made for means by which the beam
focusing elements can carry out a controlled movement
along lines which are parallel to the axis of the cylind-
rical object, Eor the formation of patterns of places of :
a material layer treated with a laser beam on the in~ide ;~
and outside of the cylindrical ob~ect.
In particular, use is made of a beam splitting ~-
device for splitting a single laser beam coming from one
laser device into two partial beams. ~ -
It was found that it is possible to use two laser
beams or to split a formed laser beam into two partial ~i
beams using a laser beam splitting device which is known
per se, and to use the two beams or partial beams for
processing material layers lying on the inside and
outside of a cylindrical object, in order to form therein
a pattern of places which have the material in question
removed from them, so that in that way an etching
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resistance pattern is formed on both sides of the cylindrical
object.
It is pointed out that a device of the type described
above as the point of departure is kncwn per se from Austrian
Patent Specification 382558 issued March 10, 1987.
The above-mentioned patent specification describes a
device in which a lacquered screen printing stencil can be
clamped on a clamping roller and a ~rogrammed laser beam is
used to burn open those holes which lie in the p~rts of the
stencil corresponding to the pattern parts which have to be
printed using the stencil. The present application describes
a device for the treatment of material layers present on the
inside and outside of a cylindrical object, such as a metal
sleeve. For this purpose, the clamping of the cylindrical
object is arranged in such a way in the device according to
the invention that the inside thereof remains free.
In its entirety, the device according to the invention
will, as indicated, comprise two laser devices with the
corresponding deflection, guide, control and regulating means.
If two lasers with separate control and regulation are used,
a separate pattern can be formed simultaneously or otherwise
on the inside and outside of a cylinder. Through coupling of
the two systems a relationship between the two patterns can
be ensured. The device according to the invention expediently
has one laser device whose beam is split into two partial
beams by means of a beam splitting device.
In order to make allowance for any wobbling of the
cylindrical object to be treated, means are advantageously
pr~esent in at least one of the beam focusing elements for
keeping constant the distance between the centre of the lens
system lorming part of a beam focusing element and the centre
of the point where the beam strikes the cylindrical object to
be treated.
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Such systems of ~eeping the distance constant are known
and described for example in JP-A-S8225107 and JP-A-6172214;
the incorporation thereof results in the distance between
focusing lens assembly and the surface of a clamped cylinder
being kept largely constant. -
For a precise determination of the distance between, for
example, a focusing lens system and an object on which
focusing has to take place, use can be made of the processes
10and devices for measuring distance described in GB-A-2066449
and GB-A-2158228.
The distance-determining means described in the latter
application can be used successfully in the means for keeping
a constant distance disclosed in the above-mentioned Japanese
publications.
In particular, it is possible with the device according `
to the invention to form patterns which have a fixed,
predetermined relationship to each other on the inside and
outside of the cylindrical element. ,~
20As will be indicated later, this can mean that the ~ ~;
patterns on the inside and outside of the metal cylinder are
identical, but it can also mean that the patterns are not
identical and are displaced relative to each other.
Finally, the invention relates to an etched metal ;~
cylinder, obtained by etching of a metal cylinder using an
etching resistance pattern which is removed after the etching
operation, characterized in that the point of departure is a ~ ~
cylinder having on the inside and outside thereof an etching - ~-
resistance pattern which was obtained by use of the process
according to the invention, as described above.
The invention will now be explained with reference to the
drawing, in which:
Fig. l shows a schematic picture of a device according
to the invention; and -~
35Fig. 2 shows in cross-section a number of ~
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possible pattern forms and pattern positionings.
Fig. 1 shows a device indicated by 1 for treating
a cylindrical metal object which is pro~ided on the
inside and outside with material layers.
5The cylindrical metal object 20 is, for example,
a seamless sleeve which is formed by electrodeposition
of nickel and is provided on the inside and outside with
a suitable organic lacquer which can be burned away
locally using laser radiation.
10The device has a laser 11 and laser guide and
splitting means 12 and 13 respectively. The beam splitter
13 divides the beam into 2 parts which can be of equal ~
or, if desired, unequal intensity. The two partial beams -
are guided via the mirror means 8, 8' and 6, 6' to the
15laser focusing means 5 and 5~, and the focus of the two
partial beams comes to lie in the centre of the material
layer which is at the inside and outside of the cylin-
drical metal object 20. The focusing point is shown
schematically by 21.
20The cylindrical metal object is clamped by means
of end rings 25 (in enlarged cross-section detail indi-
cated by 25'), rotary means and clamping means 2 and 3.
The cylindrical metal object 20, which is provi-
ded on the inside and outside with a sui~able material
25layer, i8 rotated about its axis, and during the rotation
the focusing means 5 and 5' carry out a predetermined
movement which is parallel to the axis of the cylinder
20, and during which the actuation of the partial beam
guide means is such that the partial beams can carry out
30their action on the relevant material layers as desired
and according to a predetermined programme.
During the operation the laser focusing means 5
and 5' and the appropriate deflection means 6 and 6' are
moved along spindles 4 and 4' according to a predeter-
35mined plan, in which the movement is regulated by means -
of motors 18 and 19 which are coupled to a central
logical unit. The rotation of the cylindrical object is
also regulated by means of motor 17, which is likewise
connected to the central logical unit such as a computer.
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As can be seen schematically, the position of the
partial beam focusing unit 5' is determined by making a
part of the partial beam 22 radiate through the mirror 6'
by making the latter slightly ~ransparent. The position
of the focusing device 5' is in this way fixed relative
to the optical ruler 23 whose signal is fed back via
connection 24 to the central logical unit 10. The laser -~
regulation unit 14 is also coupled to the central com-
puter, so that the computer can carry out a regulation
which according to a predetermined programme regulates `~
the displacement of the focusing units 5 and 5'; the
rotation of the cylinder 20; and the functioning of the ;`
partial beams transmitted by focusing means 5 and 5'.
The position of 5~ relative to the ruler can be ~ -
determined as indicated above. Instead of using a part of ~ ~
the beam 22, a small laser which is made to shine on the .
ruler 23 can also be connected to 5~; in this way an ;~
accurate position fixing is also possible. Even without
the use of a ruler, a position determination and reguila-
tion can take place by feeding the motor position of the
motor 18 and/or 19 back to the logical unit 10. Of ~ ;
course, such an approach is po~sible only if the mechan-
ical accuracy of the motor, coupling and spindle is great
enough and the settings thereof are reproducible.
The signal coming from a scanner can also be fed
via an interface 15 to the computer, so that a direct
translation can be produced between an original scanned
on a scanner and the pattern applied by ~he laser
irradiation to the inside and outside of a cylinder 20.
Fig. 2 shows schematically how the etching
resistance patterns on either side of the wall of a
cylindrical object can be positioned relative to each
other, and how the shapes of both etching resistance
patterns can relate to each other.
Fig. 2a shows a part of the wall of a cylindrical
object 30 on which there are patterns 31 and 32 on two
sides. The patterns show apertures 35 and 36, and it can
be seen that an etching which formed hollows 33 and 34
has already taken place. In the situation shown, the
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etching can be continued until a full perforation of the
material 30 is achieved. The etching can also be ended at
this moment or continued for a short time further to
ensure that a pattern of hollows is formed on the inside
and outside of the material, but with the material not
being fully etched through.
In the latter case a pattern of pits is obtained
on both sides of the cylindrical metal object, the total
pits being capable of containing information which can be
scanned with optical or mechanical means.
It goes without saying that such a cylinder,
which is provided on two side~ with a quantity of
information can also be cut open to form a flat metal
sheet which contains information on two sides.
Fig. 2b shows the situation in which the etching
resistance patterns 31 and 32 are in the same position
relative to each other on both sides of the cylindrical
object, but where the patterns on the two sides differ
from each other as regards open surface. During etching,
the hollow 34 will have a smaller surface than the hollow
33, due to the fact that the aperture 35 is smaller in
area than the aperture 36 (for an indication see
Fig. 2a).
Such an arrangement and formation can be
important if the lateral etching ha~ to be avoided to a
large extent at one side of the cylindrical object. In
the case illustrated here in Fig. 2b, complete etching
through of the cylinder can also be produced depending on
the envisaged purpose, while an etching oYer only part of
the total thickness can also be carried out through
doublesidedetching.
It can be seen from Fig. 2c that the patterns
formed on both sides of the cylinder differ both in shape
and in positioning. In this case an example could be a
situation in which the etching resistance pattern 31 is
of a grid nature at the top side, while the etching
resistance pattern 32 on the inside has slit-type aper-
tures which are arranged in a spiral form, and on through
etching at predetermined places a slit-type aperture
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lyins in the spiral and a hole-shaped aperture touch each
other. Fig. 2d shows the situation in which the etching
resistance patterns are the same shape, but the position-
ing of the patterns differs.
5Finally, it is also conceivable to have a situa-
tion in which the etching resistance patterns are of
different shapes on the inside and outside of the cylin~
der, and in which the positions of the two patterns bear
no relation to each other. ;
10The etching resistance patterns shown in Figs. 2a
to 2d can be formed simultaneously by laser irradiation
in both material layers (where necessary, in conjunction
with necessary developing and~or subsequent treatment ~-
steps), but they can also be formed one after the other.
15If the patterns are formed after one another, the -~
formation can still be carried out in the same movement
of the two focusing devices 5 and 5', while each of the
patterns can also be formed in a separate passage and the
focusing means 5 and 5' are actuated and controlled
20independently of each other.
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