DEVICE FOR THE FOLD-FREE STRETCHING AND HOLDING OF LIQUID CRYSTAL FILMS

DISPOSITIF PERMETTANT D'ETIRER ET DE MAINTENIR SANS AUCUN PLI LES COUCHES DE CRISTAL LIQUIDE

English Abstract

ABSTRACT OF THE DISCLOSURE
Liquid crystal films are stretched and held without
any folds by a device which consists of an outer frame with
an outer centring edge and of an insertable inner frame,
the inner boundary of the outer frame being in the form of
a stretching collar.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for the fold-free stretching and holding of liquid crystal
films, comprising a substantially rectangular outer frame having an inner
centering edge and an insertable inner frame comprising an external centering
edge, wherein the inner boundary of the outer frame is in the form of a
stretching collar, the surface of the collar facing the inner frame centering
edge being bevelled, the lower edge of the stretching collar being rounded
off and its surfaces being smooth, the surface of the stretching collar fac-
ing away from the inner frame centering edge being bevelled at a steeper
angle than that surface facing the inner frame centering edge, and wherein
the inner frame comprises a stretching groove which cooperates with the
stretching collar and the surface of the inner frame directed towards the
inner edge of the inner frame is bevelled parallel to the bevel of the stret-
ching collar, the corners of the inner boundary of the outer and inner frame
being rounded off, the outer frame being insertable in the inner frame by
cooperation of the inner and external centering edges and cooperation of
stretching collar and stretching groove.
2. A device as claimed in claim 1, wherein clips arranged on the inner
frame engage in openings formed in the outer frame.
3. A device as claimed in claim 1, wherein a double adhesive tape is
arranged on the inside of the outer frame.
4. A device as claimed in claim 2, wherein a double adhesive tape is
arranged on the inside of the outer frame.
5. A device as claimed in claim 1, wherein said corners are rounded
with a radius of 20 to 25 mm.
6. A device as claimed in claim 4, wherein said corners are rounded
off with a radius of 20 to 25 mm.

7. A device as claimed in claim 2, wherein the clips are spaced from
and disposed outwardly of the outer frame stretching coller.
8. A device as claimed in claim 7, wherein the clips are disposed
intermediate the outer frame stretching collar and the inner frame centering
edge.
9. A device as claimed in claim 6, wherein the clips are spaced from
and disposed outwardly of the outer frame stretching collar.
10. A device as claimed in claim 9, wherein the clips are disposed
intermediate the outer frame stretching collar and the inner frame centering
edge.
11. A device according to claim 2, wherein said corners are rounded off
with a radius of 20 to 25 mm and the clips are spaced from and disposed out-
wardly of the outer frame stretching collar.
12. A device as claimed in claim 11, wherein the clips are disposed
intermediate the outer frame stretching collar and the inner frame centering
edge.

Description

1055589
This invention relates to a device for the fold-free stretching
and holding of liquid crystal films.
Liquid crystal films intended to be used for the thermographic
diagnosis of cutaneous or sub-cutaneous disorders, for example breast cancer
tDours, have to be stretched without any folds. At the same time, they
must not be overstretched. The most common method of stretching and fixing
very thin liquid crystal films is to insert the films into smooth frames and
bond them in position. This method is time-cons D ing and, once the film has
been inserted, any errors in its positioning cannot be corrected.
The object of the invention is to provide a frame in which a liquid
crystal film can be automatically stretched free from any folds without at
the same time being destroyed, the film being fixed in position once it has
been stretched across the frame.
According to the invention there is provided a device for the
fold-free stretching and holding of liquid crystal films, comprising a
substantially rectangular outer frame having an inner centering edge and
an insertable inner frame comprising an external centering edge, wherein
the inner boundary of the outer frame is in the form of a stretching collar,
the surface of the collar facing the inner frame centering edge being
bevelled, the lower edge of the stretching collar being rounded off and
its surfaces being smooth, the surface of the stretching collar facing
away from the inner frame centering edge being bevelled at a steeper angle
than that surface facing the inner frame centering edge, and wherein the
inner frame comprises a stretching groove which cooperates with the stretch-
ing collar and the surface of the inner frame directed towards the inner
edge of the inner frame is bevelled parallel to the bevel of the stretching
collar, the corners of the inner boundary of the outer and inner frame being
rounded off, the outer frame being insertable in the inner frame by cooper-
ation of the inner and external centering edges and cooperation of stretch-
ing collar and stretching groove.
--1--
B

~055589
The particular advantage of the device according to the invention
is that a 1iquid crysta~ film may be placed loosely over the frame in its
open position, after whiCh the frame Can be closed. The liquid crystal film
is carefully stretched by being drawn over the rounded etges of the stretch-
ing collar. By virtue of the fact that the surfaces are smooth (through the
polished surfaces of the injection mould), the liquid crystal film slides
over the surface of the stretching collar during stretching without being
damaged. The corners of the inner boundary of the outer frame and inner
frame are rounded off in such a way that the liquid crystal film cannot
develop any fold in this zone either. After stretching, the film is kept in
its stretched position by the frame.
In a preferred embodiment of the device according to the invention,
clips are arranged on the outer frame which are designed to engage in corre-
sponding openings formed in the inner frame. By virtue of this measure, the
inner and outer frame are held together and the liquid crystal film is fixed
in its stretched position. The outer and inner frames can only be taken
apart using special tools.

1055589
This measure precludes unauthorised removal of the liquid crystal
film.
In another embodiment of the device according to the invention,
a double adhesive tape is arranged on the inside of the outer frame.
~ , 1~ .
This causes the edges of the foil to adhere to one of the frame portions.
1 or- 3.
One exemplary embodiment of the device according to the
invention is described in more detail in the following with reference
to the accompanying drawings, wherein:
Figure 1 is a plan view of a device according to the invention.
Figure 2 is a section on the line A-B of Figure 1.
An inner frame 2 is fitted into an outer frame 1. The two
frames are held firmly ~ogether by clips 3. The corners of the inner
boundary of the outer and inner frames are rounded off with a radius
of curvature of from 20 mm to 25 mm. A stretching collar 4 is bevelled
at an angle of 45 towards a centering edge 5. The upper part of the
stretching collar has a radius of approximately 1.2 mm. The surface
of the stretching collar directed away from the centering edge has an
inclination of 5.
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