Note: Descriptions are shown in the official language in which they were submitted.
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DEVICE AND METHOD FOR PRODUCING A DATA CARRIER
The present invention relates to an apparatus and a method for
producing a data carrier having at least two substrates adhered with a
two-sided adhesive film.
Such data carriers are, for example, optical recording media
such as DVDs, etc., that comprise at least two substrates adhered to
one another. In one known apparatus for producing such a data
carrier, as is known for instance from application DE-A-197 18 4i'1,
from the same applicant, two substrates were adhered to one another
by means of a lacquer. Typically the lacquer is applied to the center of
one of the substrates, which is then centrifuged in order to achieve the
most uniform possible film of lacquer on the substrate. In addition,
residual lacquer is centrifuged off of the substrate and must later be
disposed of in a complex process. Once the layer of lacquer has been
applied, the substrates are joined, whereby prior to their joining one of
the substrates is bent such that it first comes into contact with the other
substrate only in a central region. As the substrates are joined this
bending is gradually eliminated so that the other regions of the wafers
also come into contact with one another. This bending is
advantageous for preventing air from being trapped between the
substrates, which could affect the usability of the data carrier thus
produced. However, both the centrifuging of the substrates when the
layer of lacquer is applied and the bending of the substrates when they
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are joined involve the risk of damaging the substrates. In addition, the
process for applying the lacquer is very complex, and it is not always
possible to obtain a uniform layer of lacquer throughout a plurality of
lacquering processes. Furthermore, it is very time-consuming and
expensive to dispose of the residual lacquer that is centrifuged off
during the centrifuging process.
Known from EP-A-0 854 477 is a method for producing a data
carrier in which two substrates are adhered to one another by applying
to a first substrate a film that is coated on two sides with adhesive,
aligning a second substrate with respect to the first substrate, and
joining the substrates. The coated film maintained on a carrier film is
moved over the first substrate using a transport apparatus, held in this
position, and then using an elastic ram is moved into contact with the
substrate and pressed thereupon. Then the ram is moved away from
the substrate and the carrier film is withdrawn from the coated film
using a roller.
In this process there is the risk that air bubbles that have a
negative impact on the quality of the data carrier can be trapped
between the substrate and the adhesive film. In addition, the process
for applying the adhesive film is very time-consuming because
movement of the film during the pressing and subsequent withdrawal of
the carrier film must be stopped.
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Starting with the apparatus described in the foregoing and the
method for producing the data carrier, the object of the present
invention is to provide an apparatus and a method that make it possible
to produce a high-quality data carrier simply and cost-effectively, in
particular without trapping any air. The object of the present invention
is furthermore to decrease the processing times required for adhering
two substrates.
According to the present invention, there is provided a method
for producing a data carrier in which at least two substrates are
adhered to one another by
applying to a first substrate an adhesive film that is adhesive on
two sides; aligning a second substrate with respect to said first
substrate; and
joining said substrates to one another, characterized in that said
adhesive film is applied to said first substrate by pressing the adhesive
film onto said first substrate using a rotating pressure roller while said
first substrate and said pressure roller are moved relative to one
another.
According to the present invention, there is also provided an
apparatus for producing a data carrier with at least two substrates
adhered to one another, with
a laminating station for applying to a first substrate an adhesive
film that is adhesive on two sides; and a substrate adhering station for
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aligning and joining said substrates, characterized in that said
laminating station has a rotatable pressure roller and a device for
moving at least one of said first substrate and said pressure roller
relative to one another.
The following provides a non-restrictive outline of certain
possibly preferable features of the invention which will be more fully
described hereinafter.
Pressing the adhesive film onto the substrate using a rotating
pressure roller white the first substrate and the pressure roller are
moved relative to one another prevents air from being trapped between
the substrate and the adhesive film because the film is pressed onto
the substrate along a straight line in a controlled manner. Furthermore,
the movement of the film does not have to be stopped, which results in
a continuous process. In addition to applying the film, the carrier film
can be removed from the adhesive film in the same work step, thus
accelerating the process even further.
In accordance with one particularly preferred embodiment of the
present invention, during or after its application to the first substrate the
adhesive film is withdrawn from a carrier film that has a required
stability for making it possible to transport the adhesive film. The
carrier film furthermore prevents one side of the adhesive film from
prematurely adhering to other objects and prevents contamination of
the adhesive film. Preferably a protective film is withdrawn from the
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side of the adhesive film opposite the carrier film prior to applying the
adhesive film to the first substrate, the protective film preventing
contamination of the other side of the adhesive film prior to adhering to
the first substrate.
In order to ensure that the substrates adhere well and uniformly,
the shape and size of the adhesive film corresponds to those of the
surfaces of the substrates to be adhered. This ensures that the
substrates are adhered to one another across their entire surface and
that no adhesive film projects over the surfaces that are not to be
joined. Sections of the adhesive film that correspond to the shape and
size of the substrates are preferably punched onto the carrier film. The
adhesive film is preferably applied centered on the surface of the
substrate to be adhered in order to achieve the advantages cited
above. For this purpose the adhesive film and the substrate are
aligned with one another prior to application.
The pressure of the pressure roller is preferably controlled.
Prior to pressing by the pressure roller, the adhesive film is
preferably held at a pre-specified angle relative to the surface of the
substrate in order to ensure that the adhesive film does not come into
contact with the surface of the substrate prior to the pressure from the
pressure roller. This ensures uniform pressure on the adhesive film
and prevents air from being trapped between adhesive film and
substrate. Preferably the substrate and the pressure roller are moved
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relative to one another while the adhesive film is being applied. The
substrate is preferably moved past the pressure roller linearly, and the
pressure roller is preferably rotated about its longitudinal axis
synchronously to the movement of the substrate in order to
continuously adhere the adhesive film to the substrate.
In one preferred embodiment of the present invention, after the
adhesive film has been applied to the first substrate the substrates are
placed on a centering and holding element to align them. This ensures
that the substrates are aligned with one another prior to being joined.
The centering and holding element preferably spaces the substratEa
apart prior to their joining.
The substrates are preferably joined in a vacuum in order to
prevent air from being trapped between the substrates. For joining the
substrates, these are preferably pressed together in order to ensure
good contact. Preferably the pressure exerted on the substrates is
controlled. The adhesive film preferably responds to pressure and the
adhesiveness changes depending on the pressure exerted. The
adhesive film is hardened in another exemplary embodiment of the
invention.
The advantages cited with regard to the method are achieved
with the aforesaid apparatus.
Advantageously the apparatus has a centering and holding
device that in a first position holds the substrates spaced from one
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another and in a second position enables centered joining of the
substrates. The substrate adhering station preferably has a vacuum
chamber in order to prevent air from being trapped between the
substrates. The vacuum chamber advantageously has a hood and a
base that is formed in one embodiment by a substrate support element
that is part of the centering and holding device. Using the centering
and holding device as a part of the vacuum chamber makes it possible
to reduce the size of the vacuum chamber, and thus the costs
associated with deaerating the vacuum chamber, to a minimum.
Preferably the substrate adhering station has a pressure ram in order
to securely join the substrates. The pressure ram is preferably parallel
to a support surface of the substrates in order to ensure that the
substrates are pressed together uniformly. In an alternative
embodiment, an apparatus is provided for applying compressed air to
one of the substrates, which makes it possible to press the substrates
together in a particularly uniform manner.
In accordance with one preferred embodiment of the present
invention, the pressure ram has an element for actuating the centering
and holding device between the first and second positions for
controlled release of the holding function in the device for joining the
substrates.
The adhesive film is advantageously one layer of an adhesive,
whereby a film that is coated on both sides can be omitted. The use of
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one layer of pure adhesive improves the optical properties in the joining
region of the substrates.
The present invention is explained in greater detail in the
following using preferred exemplary embodiments with reference to the
figures, in which:
Fig. 1 is a schematic representation of an apparatus for
producing data carriers in accordance with the
present invention;
Fig. 2 is a schematic view of parts of a laminating station
in accordance with the present invention;
Fig. 3 is a side view of an alternative embodiment of a
laminating station in accordance with the present
invention;
Figs. 4a-4c illustrate a substrate adhering station for aligning
and joining substrates in accordance with the
present invention during various method steps.
Figure 1 illustrates an apparatus 1 for producing a DVD with tVVo
adhered substrate halves.
The apparatus has first and second feed units 3, 4 for feeding
two substrate halves that form a DVD once they have been adhered. A
first substrate half 6 from the first feed station 3 is conveyed to a
laminating station 7 that is described in greater detail with reference to
Figures 2 and 3. In the laminating station, a pressure-sensitive
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adhesive tape or film is applied to the surface of the substrate half 6 to
be adhered. The terms adhesive tape and adhesive film are to be
understood as a layer of adhesive without a carrier material. The
optical properties of a layer of adhesive can be controlled more
precisely and better than those of a carrier material coated on both
sides, as is known, for instance from EP A 0 854 477, cited in the
foregoing. The first substrate half 6 is subsequently transported to a
rotary table 8 and placed on a centering and holding device that is
described in greater detail with reference to Figures 4a - c. Then the
rotary table is rotated into a position in which a second substrate half
10 is also placed on the centering and holding device, whereby the tvvo
substrates are held centered over one another with a gap located
between them, as will be described with reference to Figures 4a - c.
Then the rotary table is rotated further until the substrate halves
arranged above one another are arranged in a processing station 11
for joining the substrates. The processing station 11 is described in
more detail with reference to Figures 4a - c.
Once the substrate halves have been joined, they are rotated to
an unloading position and loaded onto another rotary table. The rotary
table transports the joined substrates to a scanning unit 16 in which the
joined substrates are scanned to determine if they have been
damaged. If there is damage, they are deposited in a station 18 and
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then discarded. Otherwise they are deposited on a table 20 and
collected for further processing.
The apparatus 1 is arranged in a clean room in which each of
the work steps can be performed under clean room conditions.
Figures 2 and 3 are schematic representations of a laminating
station 7 in accordance with the present invention, whereby the
components of the laminating stations 7 illustrated in Figures 2 and 3
are arranged somewhat differently. However, the same reference
numbers are used for identicallsimilar components in the following
description of the laminating station in accordance with Figures 2 and
3.
The laminating station 7 has a feed roller 22 on which a tape-like
laminating film 23 is rolled. The laminating film 23 comprises a total of
three films, namely, a protective film 24, an adhesive film (adhesive
layer) 25 that is adhesive on two sides, and a carrier film 26, as can tie
best seen in the enlarged circular detail in Figure 2. The adhesive film
has sections 27 that are punched corresponding to the size and
shape of a surface of the substrate half 6 that is to be adhered. The
adhesive layer is an adhesive film that reacts to pressure and that is
20 generally known as PSA tape, the adhesion properties of which can tie
adjusted via the pressure exerted.
The laminating station furthermore has a take-up roller 28 on
which the remainder of the laminating film 23 is taken up after a
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laminating process. The laminating film 23 is conducted between the
feed roller 22 and the take-up roller 28 around a plurality of guide
rollers 30 through 38 in order to provide a defined path for the tape-like
laminating film 23 between the rollers 22 and 28. Each of the rollers 30
through 38 is rotatable about its axis of rotation, and the rollers 31 and
37 are designed as so-called compensating rollers that are borne
movable in the horizontal direction in order to make it possible to
compensate for the length of the laminating film 23 between the rollers
22 and 28. This makes it possible for the rollers 22 and 28 to be
rotated at a constant speed despite discontinuous laminating cycles, as
will be described in the following. The parts of the adhesive film 25 that
are not needed can be removed in advance, that is, prior to introducing
the laminating film into the laminating station, for instance during
production of the laminating film, or they can remain on the film in order
to ensure a uniform thickness of the film 23 across the entire width and
length thereof, at least prior to a laminating process.
The laminating film 23 is furthermore conducted around a
wedge-shaped blade 40, where the laminating film 23 turns sharply in
order to make it possible to remove the protective film 24 from the
laminating film 23 so that one side of the adhesive film 25 is exposed
for adhering to one substrate half 6. The removal of the protective film
24 is best seen in Figure 3. Once removed, the protective film 24 is
rolled onto a roller (not shown in greater detail). An alternative type of
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film removal device could also be used instead of the wedge-shaped
blade 40.
Once the laminating film 23 has been conducted around the
blade 40, it is conducted around the roller 33 that is lower with respect
to a horizontal and that is embodied as a pressure roller. After the
roller 33, the laminating film 23 is conducted about the shaft 34, which
is driven via a motor 42.
Rotation of the driven roller 34 causes corresponding rotation of
the pressure roller 33 and a downstream roller 35 that is embodiE:d
purely as a guide roller.
The laminating station 7 has a first sensor 45 that is associatE:d
with the driven roller 34 and that is able to detect contours in the
punched sections 27 of the adhesive film 25. The laminating film 23 is
moved back and forth in the longitudinal direction via the driven roller
34 until the sensor 45 detects a certain contour of the punchE~d
sections 27, such as for instance a punched center hole. When the
sensor 45 detects the center hole, it is positioned directly over one
edge of the center hole by the movement of the film, this resulting in
precise alignment of the section 27 with respect to the roller 34 and in
particular the pressure roller 33 in the longitudinal direction of the
laminating film 23.
The laminating station 7 furthermore has a support and transport
unit 47 for the substrate half 6 to be laminated. The support and
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transport unit 47 forms a horizontal support for the substrate half 6 and
can be moved in any direction via suitable moving apparatus (not
shown in greater detail). A lowerable centering pin 48 ensures precise
alignment of the substrate half 6 on the support and transport unit 47.
The pin 48 can be lowered during the laminating process so that it is
not impaired. This is achieved in that it is pressed upward into the
position shown in Figure 3 by a spring with relatively limited spring
force. When pressure is exerted on the pin from above, it is pressE:d
downward against the spring force. Alternatively, the pin can be
moved via a cylinder or motor.
Prior to the lamination of the substrate 6, the transport and
support unit 47 is moved in the X direction, which corresponds to the
longitudinal direction of the laminating film 23, against a stop. This
ensures that the substrate 6 and the section 27 of the adhesive film 25
previously aligned in the longitudinal direction are aligned to one
another. Then the transport and support unit 47 is moved back and
forth in the Z direction, which runs transverse to the longitudinal
direction of the laminating film 23. A sensor pair 50 allocated to the
transport and support unit 47 detects a contour, such as for instance
the contour of a center hole, of the punched section 27 of the adhesive
film 25, which makes it possible to laterally align the substrate half 6
with respect to the section 27.
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Once the substrate half 6 has been aligned in the above manner
both in the X direction and in the Z direction with respect to the section
27 of the adhesive film 25, the transport and support unit 47 is raised in
the Y direction. Now the motor 32 drives the roller 34, which causes
the laminating film 23 to move in the X direction. At the same time and
synchronized with the rotation, the transport and support unit 47 is
moved in the X direction. The section 27 comes info contact with the
surface of the substrate 6 to be adhered and is pressed thereagainst
by the pressure roller 33 so that it adheres to the substrate half 6 and
detaches from the carrier film 26. The synchronized movement of the
drive roller 34 with the transport and support unit 47 applies a section
27 of the adhesive film 25 centered on the substrate half 6 so that the
section 27 of the film 25 completely covers the side of the substrate
half 6 to be adhered and does not project over the edge. The pressure
of the pressure roller in the Y direction is controlled via the position of
the transport and support unit 47 in order to control the adhesion
properties of the adhesive film 25. Alternatively, of course, the
pressure roller 33 can move in the direction of the transport and
support unit. A spring-type suspension system can be provided for
good control or compensation of the pressure. The spring-type
suspension can be provided via a spring or compressed air cylinder.
Then the substrate half 6 thus provided with the section 27 of
adhesive film 25 is transported via a suitable handling apparatus 52,
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such as an interior hole gripper, removed from the transport and
support unit 47, and is transported to the rotary table 8 in accordance
with Figure 1.
A new substrate half 6 is loaded onto the transport and support
unit 47, and the process is repeated. As was mentioned in the
foregoing, the rollers 22 and 28 rotate continuously during the entire
process, although the adhering process is not continuous. The
longitudinal compensation of the laminating film 23 that is therefore
necessary is achieved via a horizontal movement of the compensating
rollers 31 and 37, as already mentioned in the foregoing.
Although the laminating film has three layers in accordance with
the description in the foregoing, namely a protective film 24, an
adhesive film 25, and a carrier film 26, it should be noted that it is not
absolutely necessary for there to be a protective film 24. However, if
no protective film 24 is used, at least the rollers 30 and 32 should be
specially coated in order to prevent the exposed adhesive film 25 from
adhering to these rollers. Furthermore, the adhesive film 25 must also
not be a film that responds to pressure, and it can also be formed by a
carrier material coated on two sides instead of one purely adhesive
layer.
Alternatively, the rollers up to the roller 33 can be omitted,
whereby in this case the rollers 22 and 28 must be controlled such that
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the sections 27 are aligned and a movement of the laminating film 23 is
achieved synchronized with the transport and support unit 47.
In addition, a single sensor, such as for instance a camera, can
be used for the above alignment processes instead of the sensors 45
and 50.
Once the substrate half 6 has been removed from the laminating
station, as already mentioned it is placed onto the rotary table 8, which
has four arms 55 with substrate receiving units 56 suspended thereon.
The receiving units 56 are suspended on the arms 55 via
mounting flanges 57, as can be seen in Figures 4a - c. The support
unit 56 can be raised from the suspension, as Figure 4c illustrates.
The receiving unit 56 has a support plate 58 with an even or
planar surface 59 upon which the first substrate half 6 is placed, as
Figures 4a - 4c illustrate. The receiving unit 56 furthermore has a
centering and holding pin 60 with movable holding noses 61 that are
able to hold the second substrate half 10 over the first, IaminatE;d
substrate half 6 with a gap 63, as Figure 4b illustrates. On the same
date it filed the instant application, this applicant filed a patent
application no. CA 2,374,582 entitled, "Apparatus for Joining
Substrates", which describes the design and precise function of the
holding pin 60. In order to avoid repetition, please refer to this
application.
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The rotary table 8 brings each of the arms 55 with the receiving
units 56 sequentially into different positions that are labeled 1, 2, 3, and
4 in Figure 1.
In a first position, a laminated substrate half 6 is placed on the
receiving unit 56. The substrate half 6 is moved via the noses 61 of the
centering and holding pin 60 until it is supported on the even surface
59 of the support 58, as Figure 4a illustrates.
Then the receiving unit 56 is moved into the position labeled 2.
There the second substrate half 10 is likewise placed on the substrate
receiving unit 56, whereby the pin 60 centers the substrate half 10 and
holds it spaced over the first substrate half 6, as Figure 4b illustrates.
Then the receiving unit 56 is moved into position 3 in the joining
station 11.
In the joining station 11, the receiving unit 56 is placed on a
support 63 by lowering the arm 55 of the rotary table 8, as the arrow in
Fig 4c indicates. Now the receiving unit 56 is completely borne by the
support 63 and is largely detached from the arm 55 of the rotary table
8. Furthermore, in the joining station a hood 65 is moved over the
receiving unit 56 and sealingly brought into contact with the evE:n
surface 59. This forms a closed chamber 66 between the hood 65 and
the support 58 in which the substrate halves are received. The
chamber 66 can be deaerated or vented via an apparatus (not shown
in greater detail). A ram 67 is received vertically movable in the
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chamber 66 and extends in a sealed manner through an upper wall of
the hood 65. In order to ensure the integrity of the chamber 66, the
part of the ram 67 extending through the upper wall 65 is surrounded
by a bellows (not shown in greater detail), one end of which is sealingly
attached to the ram 67 and the other end of which is sealingly attached
to the upper wall of the hood 65.
The ram 67 is vertically movable within the chamber 66, as the
double arrow in Fig. 4c indicates. In Figure 4c, the ram 67 is shown lin
a lowered position in which it presses the first and second substrate
halves 6, 10 together. When pressing the substrates together, the ram
67 presses the substrate half 10 in the direction of the substrate half 5,
whereby the noses 61 are pressed into the pin 60. In this process, the
substrate half 10 is guided centered very precisely relative to the first
substrate half 6 by the pin 60.
The noses can be pressed into the pin 60 by the forces exerted
on the substrate 10. Alternatively, the noses can also be withdrawn
into the pin 60 by an actuating mechanism provided in the ram. Such a
mechanism is described for instance in the patent application cited
above.
The pressure from the ram is controlled by a control apparatus
(not shown in greater detail).
After the two substrate halves 6, 10 have been pressed
together, the chamber 66 is aerated and then the ram 67 is raised
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together with the chamber 66. Then the arm 55 of the rotary table 8 is
raised again in order to receive the receiving unit 56 again, and then it
is moved further into position 4. There the two joined substrate halves
are removed, placed on another rotary table 14, and processed further,
as described with reference to Figure 1.
The present invention was described in the foregoing using a
preferred exemplary embodiment of the invention, without, however,
being restricted to this special exemplary embodiment. In particular,
the apparatus described and the method described are not limited vto
joining DVDs. In addition, it is possible, for instance, to replace the ram
67 with an apparatus that presses the two substrate halves 6, 10
together by means of compressed air. Such an apparatus has for
instance an interior and an exterior O-ring on a plate in order to form a
sealed chamber between the plate and a back side of the second
substrate half 10. This chamber can be subjected to compressed air
via the plate in order to press the two substrate halves together. This
would result in a very uniform surface pressure that is contactless
except for the O-rings, thus preventing limitations of the optical
properties of the substrate half, for instance by scratching the back side
of the second substrate half 10. A similar apparatus could also
alternatively or additionally be formed in the receiving unit 56. The
adhesive film used can be a so-called PSA tape that changes its
adhesive properties depending on the pressure applied. Alternativel~,y,
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the adhesive film can also be hardenable. The second substrate half
can be made of an elastic material, such as a protective tape, which
protects the surface of the substrate adhered with the adhesive film.
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