U.S. patent application number 12/244488 was filed with the patent office on 2009-10-22 for mask support, mask assembly, and assembly comprising a mask support and a mask.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Stefan Bangert, Heike Landgraf, Uwe Schuessler.
Application Number | 20090260566 12/244488 |
Document ID | / |
Family ID | 39680985 |
Filed Date | 2009-10-22 |
United States Patent
Application |
20090260566 |
Kind Code |
A1 |
Landgraf; Heike ; et
al. |
October 22, 2009 |
MASK SUPPORT, MASK ASSEMBLY, AND ASSEMBLY COMPRISING A MASK SUPPORT
AND A MASK
Abstract
A mask support 10 comprises a frame element 20 and an elastic
element 30. The elastic element 30 is fixed to the frame element
20. The elastic element 30 is a component integrally formed of a
flexible material. It comprises a lever or arm portion 37 having a
first engagement protrusion 38 extending in an angle of
approximately 90.degree. from the free end of the arm portion 37. A
mask assembly 40 comprises a laminar mask 41, e.g. manufactured
from a thin metal foil, and connecting elements 42. The connecting
elements 42 include an engagement portion 43 for engagement with
the engagement protrusion 38 of the elastic element 30. The mask 41
may be attached/stretched to the mask support 10 as well as to
detached from the mask support 10 comfortably.
Inventors: |
Landgraf; Heike;
(Bruchkoebel, DE) ; Schuessler; Uwe;
(Aschaffenburg, DE) ; Bangert; Stefan; (Steinau,
DE) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
39680985 |
Appl. No.: |
12/244488 |
Filed: |
October 2, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61046133 |
Apr 18, 2008 |
|
|
|
Current U.S.
Class: |
118/504 |
Current CPC
Class: |
B05C 21/005 20130101;
G03F 7/12 20130101; Y10T 29/49863 20150115; C23C 14/042 20130101;
C23C 14/04 20130101; Y10T 29/49826 20150115; H05B 33/10
20130101 |
Class at
Publication: |
118/504 |
International
Class: |
B05C 11/00 20060101
B05C011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2008 |
EP |
EP08103619.6 |
Claims
1. A mask support for supporting a mask, particularly for
supporting a laminar mask for use in an OLED coating device,
comprising a frame element and a plurality of elastic elements;
wherein both a first elastic element and a second elastic element
of said plurality of elastic elements comprise a first engagement
means arranged at said first elastic element and a said second
elastic element, respectively, for engagement with a corresponding
second engagement means provided at said mask assembly for carrying
said mask; wherein said elastic elements are configured for fixing
said mask to said frame element and for stretching said mask
supported in said frame element by pushing an edge portion of said
mask away from said frame element, and said first elastic element
and said second elastic element are arranged adjacent to each other
along a substantially straight edge of said frame element.
2. The mask support of claim 1, wherein said elastic elements are
configured for detachably attaching said mask to said frame
element.
3. The mask support of claim 1, wherein both said first elastic
element and said second elastic element comprise a lever or arm
portion, and said first engagement means of said first elastic
element and said first engagement means of said second elastic
element comprise a protrusion extending in an angle from said lever
or arm portion.
4. The mask claim 1, wherein both first elastic element and said
second elastic element comprise a curved portion arranged between
said lever portion and a mounting portion for mounting said first
elastic element and said second elastic element, respectively, to
said frame element.
5. The mask support of claim 4, wherein said first elastic element
and said second elastic element have a different structure.
6. The mask support of claim 5, wherein said curved portion of said
first elastic element and said curved portion of said second
elastic element comprise a different number of curves.
7. The mask support of claim 1, wherein said first engagement means
of said first elastic element and the first engagement means said
second elastic element are movable relative to said frame element
at least from a first position in which the respective elastic
element is in a released state to a second position in which the
elastic element is in a compressed state for locking the mask to
the frame element and stretching said mask.
8. The mask support of claim 1, wherein said first engagement means
of said first elastic element and said first engagement means of
said second elastic element are rotatably arranged at said frame
element.
9. The mask support of claim 1, wherein both said first elastic
element and said second elastic element are integrally formed of a
flexible material.
10. The mask support of claim 1, wherein both said first elastic
element and said second element are arranged along at least a
marginal edge of said frame element.
11. The mask support of claim 1, wherein said first elastic element
and said second elastic element are configured to exert different
stretching forces to said mask assembly.
12. The mask support of claim 1, wherein at least a portion of said
first elastic element and a portion of said second elastic element
are made of different materials.
13. The mask support of claim 1, wherein at least a portion of said
first elastic element and a portion of said second elastic element
have different thickness.
14. A mask assembly provided for attaching a mask to a mask support
according to claim 1, wherein said connecting means comprises at
least a second engagement means for mutual engagement with the
first engagement means of said mask support.
15. The mask assembly of claim 14, wherein said second engagement
means comprises a cramp formed by bending at least an edge portion
of said mask assembly relative to the surface of the mask.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a mask support for
supporting a mask, particularly for supporting a laminar mask for
use in an OLED coating device, comprising a plurality of elastic
elements, wherein both a first elastic element and a second elastic
element of the plurality of elastic elements comprise a lever or
arm portion and a first engagement means arranged at the first
elastic element and the second elastic element, respectively, for
engagement with a corresponding second engagement means provided at
the mask assembly for carrying the mask, wherein the elastic
elements are configured for fixing the mask to the frame element
and for stretching the mask supported in the frame element.
PRIOR ART
[0002] In the production of OLED devices, e.g. OLED displays,
shadow masks are used for generating a coating having a patterned
structure on a substrate. Usually the masks are mask foils made of
a thin metal sheet. In order to provide a reliable support and
adjustment of the mask foil, the mask foil is fixedly connected
with a frame element, e.g. by soldering. Alternatively, the mask
may be removably fixed to the frame element, e.g. by screw
fitting.
[0003] It is known that the production and the use of shadow masks
in an OLED process cause considerable costs. When the mask foils
are fixedly connected with mask frames, the number of masks
required for every pattern and for a continuous production process
is quite high. Furthermore, the reuse of mask frames having mask
foils soldered thereto is limited due to the fact that exchanging a
mask foil requires removal of material from the mask frame. Reusing
the mask foils is not possible at all.
[0004] On the other hand, exchanging a mask foil fixed to the frame
by a screw fitting connection is quite elaborate and time
consuming.
[0005] Document EP 1 437 926 A1 discloses a metal mask which is
fastened by a stationary mask clamp and a movable mask clamp. The
stationary mask clamp is fixed to a base plate and the movable mask
clamp is fixed to a slider by bolts. For stretching the mask coil
springs are arranged between the base plate and the slider.
[0006] Document U.S. Pat. No. 5,534,969 discloses a mask support
having a frame and pull-bars which pull the mask to be stretched by
means of elastic springs. The pull-bars have hook members attached
thereto which engage respective slots provided in the mask.
OBJECT OF THE INVENTION
[0007] It is an object of the present invention to provide an
improved mask assembly which allows easy handling and exchange of
masks used for the production of OLED devices, particularly for the
production of optical devices and displays, wherein the mask
assembly may be adapted to provide a required stretching force for
a particular mask.
TECHNICAL SOLUTION
[0008] This object is solved by providing a mask support according
to claim 1, a mask assembly according to claim 9, an assembly
according to claim 14, and a method according to claim 16.
[0009] A mask support for supporting a mask, particularly for
supporting a laminar mask for use in an OLED coating device,
comprises a frame element and a plurality of elastic elements. Both
a first elastic element and a second elastic element of the
plurality of elastic elements comprise a first engagement means
arranged at the first elastic element and the second elastic
element, respectively, for engagement with a corresponding second
engagement means provided at the mask assembly for carrying the
mask, wherein the elastic elements are configured for fixing the
mask to the frame element and for stretching the mask supported in
the frame element by pushing an edge portion of said mask (41) away
from said frame element. The first elastic element and the second
elastic element are arranged adjacent to each other along a
substantially straight edge of the frame element.
[0010] Attaching the mask to the frame element is accomplished by
means of a plurality of elastic elements, e.g. tongues or springs,
which engage corresponding connecting means (e.g. a cramp) provided
at the mask foil. The cramp may be provided by bending the edge
portion of the mask assembly to form an acute angle between the
mask plane and the bent side. The elastic elements are also
stretching devices which, when being under tension, engage with the
connecting means of the mask and which may be released from the
mask when compressing the elastic elements.
[0011] The means for attaching (fixing) the mask to the frame
element concurrently stretch the mask while supporting it in the
frame element. Therefore, as soon as the mask is fixed to the means
for attaching the mask, the mask is at the same time stretched.
Furthermore, it is quite easy to attach and detach the mask from
the mask support due to the fact that fixing and stretching is
carried out in one step as well as releasing the tension and
detaching the mask from the mask support.
[0012] The invention is particularly useful for the production of
OLED displays. By means of the invention a mask may be arranged in
a stable position and stretched by providing an elastic element at
each of the sides of the rectangular frame element. The present
invention provides for a simple handling and exchange of structured
mask foils, thus reducing the number of masks and mask frames
required in a production process. Furthermore, the life cycle of a
mask frame is extended due to the fact that detaching a mask is a
gentle procedure and allows reuse of the mask and the mask
frame.
[0013] When producing a mask in a conventional process the metal
foil is positioned in a clamping fixture for processing, i.e. for
providing a particular structure on the mask. The clamping fixture
is particularly provided for processing the mask, whereas in the
present invention the inventive mask support may be used for
producing a mask as well as for using the mask in a coating
process. Therefore, the number of process steps may be reduced,
particularly detaching the mask from the clamping fixture after the
production of the mask and attaching the mask to another frame for
the coating process.
[0014] According to the invention a plurality of elastic elements
may be used at each side of the (usually rectangular) frame
element. There are at least a first and a second elastic element
provided at a side of the frame element. Therefore it is easy to
vary the characteristics of the elastic elements along a side of
the frame element by varying the properties of the elastic elements
arranged along a side of the frame element. By varying the
properties of the elastic elements the stretching force may be
varied, thus optimizing the shape and position of various mask
layouts with respect to a plane, crease-free arrangement of the
mask.
[0015] The characteristics of the elastic elements may be varied by
different measures as described below.
[0016] It is preferred that the elastic elements are configured for
detachably attaching the mask to the frame element.
[0017] Particularly, both the first elastic element and the second
elastic element comprise a lever or arm portion, and the first
engagement means of the first elastic element and the first
engagement means of the second elastic element comprise a
protrusion extending in an angle from the lever or arm portion.
[0018] It is preferred that both the first elastic element and the
second elastic element comprise a curved portion arranged between
the lever portion and a mounting portion for mounting the first
elastic element and the second elastic element, respectively, to
the frame element. By providing a curved portion the spring
stiffness and/or spring deflection/spring travel may be increased
without needing considerably more constructional space. Thus the
height and/or the lateral extension of the mask support are
independent from the required spring stiffness and/or spring
deflection.
[0019] Particularly, the first elastic element and the second
elastic element have a different structure. The structure or
geometry may be varied in order to generate different properties,
especially different tension, along a side of the mask
assembly.
[0020] In a preferred embodiment of the invention the curved
portion of the first elastic element and the curved portion of the
second elastic element comprise a different number of curves.
Varying the number of curves, e.g. varying the number of meanders
along the length of the elastic elements between the mounting edge
and the first engagement means, allows for a defined adjustment of
the spring stiffness and/or spring deflection/spring travel.
[0021] It is preferred that the first engagement means of the first
elastic element and the first engagement means of the second
elastic element are movable relative to the frame element at least
from a first position in which the elastic element is in a released
state to a second position in which the elastic element is in a
compressed state for locking the mask to the frame element and
stretching the mask.
[0022] The first engagement means of the first elastic element and
the first engagement means of the second elastic element are
rotatably arranged at the frame element. The engagement means is
arranged rotatably at the frame element to be rotated or swivelled
around at least one axis of rotation. Particularly, the engagement
means may be arranged to be able to be rotated around more than one
axis and/or to be able to make a translational movement. This is
due to the configuration of the elastic element.
[0023] The elastic elements may be integrally formed of a flexible
material. At least the flexible element may have a flexible
portion.
[0024] It is preferred that both the first elastic element and the
second elastic element are arranged along at least a marginal edge
of the frame element. Particularly, two opposite sides of the frame
element may each have at least two elastic element attached
thereto. The elastic elements exert forces in order to stretch the
mask in opposite directions.
[0025] The first elastic element and the second elastic element may
be configured to exert different stretching forces to the mask
assembly.
[0026] In a preferred embodiment of the invention at least a
portion of the first elastic element and a portion of the second
elastic element are made of different materials. Because different
materials have different spring stiffness the tension along the
edge of the mask assembly may be varied.
[0027] In another preferred embodiment of the invention at least a
portion of the first elastic element and a portion of the second
elastic element have different thickness.
[0028] According to the invention a mask assembly provided for
attaching a mask to a mask support as described above comprises at
least a mask and a connecting means for connecting the mask to the
means for attaching the mask to the frame element and for
stretching the mask supported in the frame element. The connecting
means comprises at least a second engagement means for mutual
engagement with the first engagement means of the mask support.
[0029] The mask may be a laminar shadow mask, particularly a shadow
mask processed from a metal sheet. A laminar mask is a shadow mask
composed of a thin metal mask sheet which has a number of apertures
to allow coating particles to pass the mask and form a pattern of
material on a substrate. When using a mask, the apertures are
polluted after some coating cycles. The present invention provides
for an easy handling and exchange of masks from a mask support and
for a quick attachment of a mask to a mask support.
[0030] In a preferred embodiment of the invention the second
engagement means comprises a cramp, e.g. formed by bending at least
an edge portion of the mask assembly or mask relative to the
surface of the mask, thereby forming an acute angle for engagement
of the first engagement means of the first and/or second elastic
elements.
[0031] The object of the invention is also achieved by an assembly
comprising a mask support as described above, and a mask assembly
as described above.
[0032] Particularly, the mask is (detachably) attached to the mask
support by means of a flexible force exerted by a compression of
the elastic elements of the mask support, the first engagement
means of the elastic elements being in engagement with the second
engagement means of the mask assembly for supporting and stretching
the mask attached to the mask support.
[0033] A method of connecting a mask assembly according to the
invention with a mask support according to the invention includes a
combination of two or more of the following steps: a) Inserting the
mask support comprising the frame element and the elastic elements
in a tensioning device; b) arranging the mask assembly comprising
the mask and the connecting means on top of the mask support; and
c) compressing the elastic elements by actuation of the tensioning
device. Afterwards, according to step d) the connecting means of
the mask assembly engages the elastic elements of the mask support
as soon as releasing the elastic elements by actuation of the
tensioning device. When releasing the elastic elements, they move
in engagement with the connecting means of the mask assembly, thus
connecting the mask foil with the frame element. Simultaneously,
the elastic force of the elastic elements keeps the mask foil under
tension.
[0034] The method may comprise a further step e) removing the
assembly comprised of the mask assembly and the mask support from
the tensioning device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Further features and advantages of the invention will be
apparent from the following description of a preferred embodiment
with reference to the appended drawings. The figures
illustrate:
[0036] FIG. 1 a portion of a mask support according to the present
invention and a mask detached from the mask support;
[0037] FIG. 2 a mask support according to the present invention and
a mask attached thereto;
[0038] FIG. 3 a perspective view of an embodiment of a mask support
according to the present invention; and
[0039] FIG. 4 a top view of an embodiment of a mask support
according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0040] FIG. 1 illustrates a portion of a mask support 10 comprising
a frame element 20 and an elastic element 30. The elastic element
30 is fixed to the frame element 20.
[0041] The frame element 20 comprises a first frame portion 21 and
a second frame portion 22 and may have a rectangular or square
configuration.
[0042] The elastic element 30 is a component integrally formed of a
flexible material. It comprises a mounting edge portion 31 which
extends into a recess 23 which is provided between the first frame
portion 21 and the second frame portion 22 of the frame element 20
along a marginal side of the frame element 20. The mounting edge
portion 31 is clamped between the first frame portion 21 and the
second frame portion 22. One or a plurality of elastic elements 30
may be arranged along a marginal edge of the frame element 20 for
enabling the elastic element to fix and stretch a mask attached to
the mask support 10 in every direction.
[0043] Furthermore, the elastic element 30 comprises a curved
portion 32 which is connected with the mounting edge portion 31.
The curved portion 32 comprises a first bend 33 of approximately
90.degree., a second bend 34 of approximately 180.degree., a third
bend 35 of approximately 180.degree. and a fourth bend of an angle
between 90.degree. and 180.degree..
[0044] A lever or arm portion 37 is connected with the curved
portion 32. The lever or arm portion 37 extends outwards away from
the frame element 20. It comprises a first engagement protrusion 38
extending in an angle of approximately 90.degree. from the free end
of the arm portion 37 to form an engagement recess 39 between the
arm portion 37 and the first engagement protrusion 38. The recess
39 is arranged relative to the arm portion 37 on the side opposite
the frame element 20.
[0045] At least a portion of the elastic element 30, particularly
the curved portion 32, is made of a flexible and/or elastic
material such that the arm portion 37 and the first engagement
portion 38 may be swivelled relative to the frame element 20 and
the mounting edge portion 31. The arm portion 37 may be swivelled
around at least one, particularly around a plurality of swivel
axes. Due to the fact that the curved portion 32 comprises a number
of bends 33, 34, 35, 36 the arm portion 37 may for example be
swivelled around the apex axes of the bends. Furthermore, the arm
portion 37 may also carry out a translational movement, e.g. by
compressing or extending the curved portion 32 in a direction
indicated by the arrow x.
[0046] In the embodiment illustrated in FIG. 1 the elastic element
30 is in an unloaded state. In this state the arm portion 37
extends in a predetermined angle relative to the frame element 20.
When being compressed in a direction indicated by the arrow C the
elastic element 30 may act like a spring or tongue and exert a
counter force indicated by the arrow F.
[0047] As shown in FIG. 1, a mask assembly 40 comprising a laminar
mask 41, e.g. manufactured from a thin metal foil, and connecting
elements 42. The connecting elements 42 include an engagement
portion 43 for engagement with the engagement protrusion 38 of the
elastic element 30. In FIG. 1 the mask 40 is out of engagement with
the mask support 10 and the elastic element 30. The mask 40 is
released from the mask support 10. Thus the mask 40 and the elastic
element 30 are detached from each other.
[0048] The connecting element 42 may be replaced by crimping the
edge portion of the mask 41 to form an acute angle between a
crimped tab and the surface of the mask 41. The recess defined
between the crimped tab and the surface of the mask 41 corresponds
to the engagement portion 43 of the connecting element 42. The
advantage of crimping or bending a tab of the edge of the mask 41
is that the engagement portion 43 may be aligned perfectly. First,
it is quite easy to bend the tab parallel or rectangular relative
to an edge of the mask 41. Second, The length of each crimped tab
portion along the edge of the mask 41 may be adjusted by forming
gaps between the crimped tab portions, e.g. by use of a laser.
[0049] In the embodiment illustrated in FIG. 1 the elastic element
30 may be composed of a plurality of separated elastic elements
30a, 30b, 30c, 30d, . . . which are arranged adjacent to each
other. Between the elastic elements 30a, 30b, 30c, 30d, . . . there
is a separation, e.g. a small gap. Thus the elastic elements 30a,
30b, 30c, 30d, . . . may be stretched or loaded independently.
Furthermore, the elastic elements 30a, 30b, 30c, 30d, . . . may
have a different structure. The structure or geometry may be varied
in order to generate different properties, especially different
tension, along a side of the mask assembly 42. Each of the elastic
elements 30a, 30b, 30c, 30d, . . . may be integrally formed of a
flexible material. For example, the elastic elements 30a, 30b, 30c,
30d, . . . or some of the elastic elements 30a, 30b, 30c, 30d, . .
. may be configured to exert different stretching forces to the
mask assembly 42. Furthermore, the elastic elements 30a, 30b, 30c,
30d, . . . or some of the elastic elements 30a, 30b, 30c, 30d, . .
. may be made of different materials or have different thickness.
Therefore, the spring stiffness the tension along the edge of the
mask assembly 42 may be varied.
[0050] FIG. 2 shows the mask support 10 of FIG. 1 with the mask
assembly 40 being attached to the mask support 10. In this state
the engagement portions 43 of the connecting elements 42 are in
engagement with the engagement protrusion 38 of the arm portion 37.
The free end of the engagement portion 43 extends into the
engagement recess 39 of the elastic element 30.
[0051] Thus the laminar mask 41 is fixed to the mask support 10 and
stretched by a force F exerted by the elastic element 30 which had
been compressed in order to fix the mask assembly 40 to the mask
support 10. It is obvious that when attaching the mask assembly 40
to the mask support 10, the arm portion 37 has to be compressed in
order to connect the connecting element 42 of the mask assembly 40
with the elastic element 30 of the mask support 10. The lever or
arm portion 37 extends above a level defined by the frame element
20 in order to keep the mask 41 stretched in a plane above the
frame element 20.
[0052] Thus, the mask assembly 40 is attached and stretched by the
elastic element 30 concurrently. When releasing the mask assembly
40 from the mask support 10 a force C (greater than F) has to be
applied to the arm portion 37 in order to compress and swivel the
arm portion 37 to be able to unhook the connecting element 42 from
the elastic element 30 and to remove the mask assembly 40 from the
mask support 10.
[0053] It is obvious that it is quite easy and comfortable to
attach/stretch the mask 41 as well as to detach the mask assembly
40 from the mask support 10.
[0054] By providing a curved portion having one or a plurality of
curves 33, 34, 35 the spring stiffness may be controlled in a wide
range by just determining the geometry of the elastic element 30.
Furthermore, the deflection or extension E, E' (cf. FIGS. 1 and 2)
of the elastic element 30 is quite small, whereas the spring
stiffness is sufficient for stretching the mask 41. The elastic
elements 30 exert a pushing shear force to the mask assembly 40
when stretching the mask 41 instead of a pulling tractive force. A
respective edge portion 42 of the mask assembly 40 is pushed in a
direction away from the frame element 20 by each of the elastic
elements in order to hold and stretch the mask. Thus the
constructional space needed for providing the inventive mask
support 10 is small. Particularly the height H of the construction
is limited and the longitudinal and lateral extension of the frame
element 20 corresponds to the longitudinal and lateral extension of
the mask assembly 40. The mask support 10 is thus quite
compact.
[0055] FIG. 3 illustrates a portion of an embodiment of a mask
support 10 according to the invention comprising a frame element 20
and a plurality of elastic elements 30a, 30b, 30c, 30d, 30e, 30f,
30g and 30h. The elastic elements 30a, 30b, 30c, 30d and 30e are
arranged side-by-side along a first edge 24 of the frame element
20. The elastic elements 30f, 30g and 30h are arranged side-by-side
along a second edge 25 of the frame element 20. The elastic
elements 30 are arranged adjacent to each other along the
respective edge 24, 25 with gaps 30' arranged between adjacent
elastic elements 30. The configuration of the elastic elements 30a,
. . . 30h is the same as indicated in FIG. 1 and 2. Due to the fact
that the elastic elements 30a, . . . 30h comprise a curved portion
32, the height H of the elastic elements 30a, . . . 30h is
substantially limited to the height of the frame element 20.
[0056] The configuration of the elastic elements 30a, . . . , 30h
may be the same or different, i.e. the configuration of one or a
plurality of elastic elements 30 may be different from the
configuration of other elastic elements 30. For example, the number
of curves formed in the curved portion 32, the geometry, the
material, the thickness or the width B of at least two elastic
elements 30 may be different. By controlling these parameters, a
particular elastic element 30 may be configured to have particular
characteristics, e.g. a particular spring force corresponding to a
translational or rotational force of the lever portion 37. By
providing different elastic elements 30 along an edge portion of
the frame element 20 the mask 41 may be more or less stretched at
different positions along the edge 42 of the mask assembly 40.
Thus, the stretching force may be adapted to each particular mask
design.
[0057] FIG. 4 shows a plan view of a mask assembly 40 comprising a
mask 41 and connecting elements 42 held at a frame element 20 by
means of elastic forces exerted by a plurality of elastic elements
30a, 30b, 30c, . . . The elastic elements 30a, 30b, 30c, . . . are
arranged side-by-side along an edge portion 24 of the frame element
20.
[0058] It is obvious from FIG. 4 that the longitudinal and lateral
extension of the frame element 20 substantially corresponds to the
longitudinal and lateral extension of the mask assembly 40. This is
due to the fact that the elastic elements 30a, 30b, 30c, . . .
provide a shear force pushing the edges 42 of the mask 41 away from
the frame element 20, i.e. the extension of the frame element 20
corresponds to or is somewhat smaller than the surface of the mask
assembly 40. Because the height H of the elastic elements 30 and
the frame element 20 is also limited, the construction of the mask
support 10 is very compact.
* * * * *