U.S. patent number 3,796,884 [Application Number 05/190,384] was granted by the patent office on 1974-03-12 for thermographic plate.
Invention is credited to Jean Tricoire.
United States Patent |
3,796,884 |
Tricoire |
March 12, 1974 |
THERMOGRAPHIC PLATE
Abstract
A process for manufacturing a thermographic plate is disclosed,
wherein a sensitive layer comprised of liquid crystals, is
associated to a heat guiding layer made of latex and producing a
screen effect perpendicularly to said sensitive layer. The
thermographic plate is used for diagnosis of several cutaneous and
subcutaneous affections. The invention relates also to the
thermographic plate itself as well as to thermographic recording
device comprising said thermographic plate and a fixture connecting
at an adjustable distance said plate with a photographic
camera.
Inventors: |
Tricoire; Jean (Paris,
FR) |
Family
ID: |
25625671 |
Appl.
No.: |
05/190,384 |
Filed: |
October 18, 1971 |
Foreign Application Priority Data
|
|
|
|
|
Oct 20, 1970 [FR] |
|
|
70.37758 |
|
Current U.S.
Class: |
430/20;
374/E11.022; 250/474.1; 430/271.1; 349/22; 349/193; 250/316.1 |
Current CPC
Class: |
G01K
11/165 (20130101); A61B 5/015 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); B41n 005/00 () |
Field of
Search: |
;250/65T ;350/16LC |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lawrence; James W.
Assistant Examiner: Church; C. E.
Attorney, Agent or Firm: Spencer & Kaye Kaye; Harvey
Finkelstein; Jay M. Kunitz; Norman N.
Claims
1. A process for manufacturing a thermographic plate comprising:
providing a sensitive layer composed of liquid crystals; and
disposing in heat conductive association with said sensitive layer
means for guiding heat energy incident thereon in a direction
perpendicular to said sensitive layer and for opposing diffusion of
such heat in directions parallel to said sensitive layer, said
means being constituted by a layer of latex.
2. A process according to claim 1, wherein said step of disposing
is carried out by depositing only one layer of heat reticulable
latex on the sensitive layer, and heating the latex layer
sufficiently to give it a
3. A process according to claim 1, wherein said step of disposing
is carried out by sequentially depositing a plurality of discrete
layers of
4. A process according to claim 3 wherein the sequential depositing
of the
5. A thermographic plate comprising, in combination a sensitive
layer composed of liquid crystals; means disposed in heat
conductive association with said sensitive layer for guiding heat
energy incident thereon in a direction perpendicular to said
sensitive layer and for opposing the diffusion of such heat in
directions parallel to said sensitive layer,
6. A thermographic plate according to claim 5, further comprising a
flexible support layer and wherein said layer of latex is disposed
between
7. A thermographic plate according to claim 6, wherein said support
layer is a sheet of non-colored ethylene glycol terephthalate
having a thickness
8. A thermographic plate according to claim 5, further comprising a
flexible support layer and wherein said layer of latex and said
sensitive layer are arranged on respectively opposite sides of said
flexible support
9. A thermographic plate according to claim 5, wherein said layer
of latex
10. A thermographic plate according to claim 5, wherein the liquid
crystals are dispersed in said layer which of latex forms said
sensitive layer.
11. A thermographic plate according to claim 5, wherein said layer
of latex
12. A thermographic plate according to claim 5, wherein said layer
of latex is composed of a plurality of discrete layers of black
latex paint each
13. A thermographic plate according to claim 5, wherein said plate
has a
14. A thermographic plate according to claim 5 further comprising a
support layer and wherein there is a plurality of sensitive layers
which are different from one another and which are associated with
said support
15. A medical device comprising: a thermographic plate as defined
in claim
16. A medical device according to claim 15, wherein said support
instrument
17. A medical device according to claim 15, wherein said support
instrument
18. A medical device according to claim 15, wherein said support
instrument is a transport plate, and said thermographic plate is
fixed at its periphery to said transport plate to form therewith an
inflatable unit presenting a sealed space between said
thermographic plate and said transport plate, and further
comprising a valve connected to communicate
19. A medical device according to claim 15, wherein said support
instrument
20. A medical device according to claim 15, wherein the liquid
crystals of
21. A medical device according to claim 15, wherein said sensitive
layer is
22. A medical device according to claim 15, further comprising a
fixed arm on which said support instrument is removably mounted,
said arm being provided with means for mounting a photographic
camera at adjustable distances from the thermographic plate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to thermographic surveys
and more particularly application of thermography to the diagnosis
of several cutaneous or subcutaneous affections such as malignant
tumours or stoppage of some blood-vessels.
2. State of the Art
As it is well known, these affections cause local thermal
anomalies, for instance in the order of 0.5.degree.C, positive in
the case of malignant tumours and negative in the case of stopped
up blood-vessels.
A classic method of diagnosis of these affections consists of
measuring the cutaneous or subcutaneous temperatures of the
interested areas.
Such a measure may be effected in an exact and direct manner by
means of the conventional thermometry, for instance with the aid of
thermometres, thermo-couples or thermistors.
However, it is difficult under these conditions to plot in a
sufficiently detailed way the general thermographic map of a
certain area.
It is now known to effect directly such a thermographic map by
means of infrared cameras. However, these apparatus are extremely
expensive, the thermographic maps they allow to obtain are not
sufficiently sharp to be satisfactory and the time required for
their establishment is relatively long.
SUMMARY OF THE INVENTION
The main object of the present invention is that of removing the
above mentioned drawbacks in a general way.
More particularly, the present invention relates to a thermographic
plate of any size suitable for the test to be effected, allowing to
obtain any desired thermographic survey in an economic and about
immediate way.
The present invention is based on the existence of the so-called
liquid crystals. Briefly speaking, liquid crystals are particles
with a molecular orientation variable according to temperature. The
light is being polarized at any reflection on these liquid crystals
and then they show to the observer a dichroism which is
characteristic of their temperature.
These liquid crystals are presently known under two different types
of preparation, namely in a free chloroformic solution or
encapsulated into gelatine.
The liquid crystals in free chloroformic solution show as main
inconvenience that of having an extremely short life when exposed
to free air; in the range of 5-10 minutes they are oxidized and are
no more able to show any dichroism.
However, one sought to apply these liquid crystals in a free
chloroformic solution, to carry out thermographic surveys. To this
end it was disclosed to paint the areas to be surveyed with these
liquid crystals, after degreasing and black painting such
areas.
In addition to the fact that this painting process is not at all
practical and the observation of the appearing dichroism must be
hasty because of the transient character of such dichroism, these
process has two more inconveniences. First, it leads to a
continuous consumption of liquid crystals which are relatively
expensive, and secondly the obtained images or surveys are
relatively fuzzy and the cause of this may be ascribed to a heat
diffusion both laterally and transversely in the layer of liquid
crystals.
Now, only a transversal heat diffusion in this layer may lead to
sharp images or surveys. It is possible to use in thermography the
gelatine encapsulated liquid crystals, which are mostly suspended
in latex; encapsulation of liquid crystals avoids that they oxidize
in free air.
It was therefore possible to propose preparation of thermographic
plates comprising a flexible support layer and a layer of liquid
crystals associated to a latex layer. However, experience shows
that images or surveys obtained by such thermographic plates have
the same evanescence inconveniences of those obtained by painting
liquid crystal in chloroformic solution.
The main object of the present invention is therefore to obtain
sharp thermographic images or surveys. The present invention is
based on the discovery that latex, applied under particular
conditions, may allow obtainment of a screen effect capable of
being used to prevent the lateral heat diffusion, which is, as
above mentioned, the main ground of the inopportune fuzziness of
the thermographic images obtained with the hitherto known
thermographic plates.
Actually, reticulation which some latexes undergo under heat, leads
to such an effect of screen perpendicularly to the latex support
layer.
However, and this is also an important discovery on which the
present invention is based, even if cold applied a layer of latex
or of usual latex paint, may lead to a screen effect similar to
that of the heat reticulable latexes, provided that in this case
such a layer consists of very thin overlapped discrete little
layers.
Thus the present invention first relates to a process of
manufacturing a thermographic plate, characterized by the fact that
to a sensitive layer comprised of liquid crystals, a heat guiding
layer is associated, showing a screen effect perpendicularly to
said sensitive layer, either if said heat guiding layer is formed
by depositing only one layer of a heat reticulable latex, or if it
is formed by sequential deposits of a plurality of little discrete
layers of latex paint each having a thickness lower than 50
microns.
The present invention also relates to a thermographic plate so
obtained, having a support layer, a heat guiding layer and a
sensitive layer.
The heat guiding layer advantageously forms a sort of oriented
screen for the heat to be transmitted to the sensitive layer,
opposing the lateral diffusion of said heat which is affecting the
sharpness of the obtained images, as already mentioned.
According to a preferred embodiment, this heat guiding layer is
arranged between the support and the sensitive layer, or on the
side of the support layer opposite the sensitive layer.
According to several variants, the heat guiding layer itself forms
the support layer and/or the liquid crystals of the sensitive layer
are directly dispersed in the heat guiding layer, which in this
case is itself the sensitive layer.
In any case a thermographic plate according to the present
invention may have very variable sizes, going from those of a
simple tablet allowing a point observation of a doubtful area up to
those e.g., of a large sized sheet of paper capable of being
applied as a whole to a relatively extended doubtful area.
In the latter case, the thermographic plate according to the
present invention is preferably supported by a flexible or rigid
frame or fixed at its periphery to a transparent plate defining
together with the thermographic plate an inflatable sealed
space.
The present invention further relates to a thermographic recording
assembly comprising said thermographic plate, an arm fixed
preferably in a removable way to the plate or the plate supporting
frame, said arm being provided with means allowing to fasten at an
adjustable distance a photographic camera.
It is to be understood that said assembly may also comprise said
photographic camera, preferably provided with a flash lamp,
allowing to take photographs of the thermographic surveys obtained
by means of the associated plate.
In any case, these surveys are almost immediate, as soon as the
plate according to the present invention is applied on the area to
be observed, and such a plate may be indefinitly reused.
The thermographic surveys obtained by the present invention are
therefore particularly economical.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and the advantages of the present invention will
become apparent from the following detailed description of the
preferred embodiments, given by way of example only, with reference
to the accompanying diagrammatic drawings, in which:
FIG. 1 is a partially sectioned view on a very enlarged scale of a
thermographic plate according to the present invention;
FIG. 2 is a view similar to FIG. 1 and relating to a variant;
FIG. 3 is a perspective view of a possible embodiment of a
thermographic plate according to the present invention;
FIG. 4 is a perspective view, with a portion taken away, of another
possible embodiment of the plate;
FIG. 5 is an exploded perspective view of a recording assembly
associated with such a plate;
FIG. 6 and 7 are perspective views showing other embodiments of the
present invention;
FIG. 8 is a perspective view showing the application of the present
invention for carrying out a thermographic plate comprising several
juxtaposed sensitive layers;
FIGS. 9A and 9B are diagrammatic sections showing a possible
interpretation of the function of the heat guiding layer,
characterizing a thermographic plate according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the embodiment shown in FIG. 1, a thermographic plate
according to the present invention comprises the sequence of a
support layer 10, a heat guiding layer 11 and a sensitive layer
12.
Thus, according to this embodiment the heat guiding layer is
arranged between the upport layer 10 and the sensitive layer
12.
As a variant in FIG. 2 the heat guiding layer 11 and the sensitive
layer 12 are arranged at the opposite sides of the support layer
10.
The support layer 10 is preferably formed by a thin not coloured
sheet of a product marketed under the trade mark "MYLAR." As it is
known, this is a film of the ethylene glycol terephtalate. Its
thickness is preferably under 0.1 mm and is for instance in the
order of that of a sheet of paper, that is in the range of four
hundredths to six hundredths of a millimetre.
The heat guiding layer is preferably made of a latex. For instance
it is a sole layer of a styrene-butadiene copolymer heat
reticulable at 150.degree.C and preferably black painted. However,
it may also consist of a latex paint available on the market,
opaque and naturally black painted, of the kind of those marketed
in aerosol form for instance under the trade marks "KRYLON,"
"NOVEMAIL," "ASTRAL-JET," "CORO-SPRAY" or "RIPO-MAT."
In such case the layer 11 is obtained by sequential deposits of
several little discrete layers, for example from four to eight
layers of such a paint.
In any case the thickness of the heat guiding layer 11 is varied
according to the requirements and it is preferably greater than
one-tenth mm and for instance is in the range of two tenth mm.
The sensitive layer 12 comprises liquid crystals encapsulated in
gelatine, dispersed in a latex. Its thickness is variable according
to the requirements and may reach three tenth to four tenth mm;
however a thickness of two tenth mm is generally proper.
In any case, the application of such a sensitive layer may be
effected by means of a coating machine or of a glass rod moved in
contact with two bands laterally arranged at a distance from one
another and forming the cross bars.
As it may be easily understood, if the heat guiding layer 11 has a
sufficient strenght, it may act itself as the support layer, and in
this case the support layer 10 is no more required. If the
sensitive layer 12 has a sufficient latex thickness, it may
likewise act itself as heat guiding layer, so that in this latter
case the layer 11 is no more required.
In any case the thermographic plate according to the present
invention is used applying it against the area to be surveyed with
its side being farther from the sensitive layer 12.
In the embodiment of FIG. 1 this application is done through the
free side of the support layer 10, while in the embodiment of FIG.
2 it is done through the free side of the heat guiding layer
11.
In any case the heat diffused from the observed area must therefore
cross the heat guiding layer 11. This promotes a transversal
diffusion of said heat according to the arrows 15 of FIGS. 1 and 2,
opposing a lateral or longitudinal diffusion of the heat.
One may ascribe the preferential orientation thus applied to the
heat diffusion by the layer 11 of the instant invention, to the
reticulated macromolecular structure of the latex forming this
layer, said reticulated structure leading to a screen effect
perpendicularly to the layer 11.
This screen effect will be better understood making now reference
to FIGS. 9A and 9B. FIG. 9A is a sectional view only of the heat
guiding layer 11 according to the instant invention, when this
layer is formed by a sole layer of heat reticulable latex; in this
case such a layer comprises a superposition of squared lattices of
molecules 100, and the heat reticulation leads to the formation of
bridges both between molecules 100 of the same lattice (bridges
101) and between molecules 100 of two subsequent lattices (bridges
102). In all these cases said bridges are forming, according to the
arrows 103, free passages between the molecules perpendicularly to
the plane of their lattices, oppsing a lateral diffusion of heat in
the plane of said lattices.
FIG. 9B relates to the case in which the layer 11 is formed by a
sequence of cold spread little discrete layers 104. In this case
there is neither reticulation between molecules 100 of the lattice
of each discrete layer, not between molecules 100 of two subsequent
discrete layers. However, experience shows that, provided that each
layer 104 is very thin so as to be formed almost by a sole
molecular latex layer, from the superposition of these discrete
layers results the same screen effect shown by the arrows 105 of
FIG. 9B; it is probable that the superposition of these discrete
layers opposes a too remarkable lateral heat diffusion between the
little discrete layers as well as at the outer surface of the layer
11 so formed.
A maximum thickness of 50 microns seems to be convenient for each
discrete little layer, the term "monomolecular" having to be
considered in a very broad sense. Use of aerosol paint allowing
application of these discrete layers by spraying, leads in a
particularly advantageous way to very reduced thicknesses. However,
it is natural that such spraying technique is not all limiting the
invention, since any process or application may be convenient
provided that it leads to very thin and preferably monomolecular
discrete layers.
The sensitive layer 12 of a plate according to the present
invention is normally black or violet at a normal temperature
chosen as a reference temperature; when the temperature of the
sensitive layer 12 exceeds the reference temperature for a fixed
amount, this sensitive layer clearly changes to red. This amount or
value, defining the sensitivity range of the layer is preferably
narrow and for instance is in the order from 1.degree. to
1.5.degree. centrigrade. Practically, the useful range of liquid
crystals presently available goes from the so-called red 27 to red
37. The plates mostly used will be those coated with red 33.
A thermographic plate according to the present invention may be
used as such, with dimensions in the range e.g., of one centimetre
or some centimetres for an almost point-to-point observation of a
doubtful area. In FIG. 3 there is shown a tablet 16 useful for such
an observation, for instance to show a stopped up blood-vessel,
thus for surveying e.g., phlebitis. In such a case the side of
application of the tablet will be preferably self-sticking.
However, a thermographic plate according to the present invention
may be also supported by a frame 17, such as that shown in FIG. 4,
particularly when said plate has relatively big dimensions; in FIG.
4 as an example a rectangular plate is shown, having each side from
20 to 30 cm long.
These plates, the outline of which may be practically of any shape,
thus even different from the rectangular one, are particularly
useful for surveying breast tumours, or with larger sizes for the
observation of abdominal organs, or with lower dimensions for
examination of vertebrae.
Frame 17 may be semirigid or flexible, for instance made of strong
cardboard or light metal, so as to allow an easy bending of the
plate born by said frame, thus a better application thereof to the
surveyed area.
Frame 17 may also be rigid, made of wood or transparent synthetic
material, e.g., opaque resin. Frame 17 may advantageously
cooperate, according to the another aspect of the present
invention, to carry out a thermographic recording assembly, such as
that diagrammatically shown in FIG. 5. In addition to the frame 17
and the thermographic plate, such an assembly comprises an arm 20
having at one end a forked mount 21 provided with lugs 22, 22' for
engaging threaded pins 23, 23' fixed to the frame 17 and designed
for cooperating with wing nuts 24, 24'. This arrangement allows
rapid and removable fastening of arm 20 to frame 17.
At its free end arm 20 has a hole 25. This allows to fasten to the
arm 20, by means of a knurled nut 26 and at an adjustable distance
from the plate born by frame 17, a photographic camera 27 of any
suitable type.
This photographic camera 27 preferably comprises a flash lamp 28
oriented according to its optical axis. Thus it is possible to
avoid any reflection on the plate supported by the frame 17 and
therefore to make very satisfactory photographic reproductions of
the dichroism shown by such a plate when it is applied to any
doubtful area.
The arm 20 may have any proper length for instance in the range
from 30 to 60 centimetres. It is to be understood that said arm 20
may be associated to different thermographic plates made according
to the present invention, and the photographic camera 27 associated
with this arm may be adjusted in advance to a precise distance
corresponding to the lenght of said arm.
According to several embodiments, a thermographic plate according
to the present invention may be also associated to any working
instrument. Thus, as shown in FIg. 6, a plate according to the
present invention may for instance be born in the curved zone 31 of
a retractor 32 made of synthetic transparent material. Such a plate
is also particularly useful for instance to survey vascular tracts.
In the same way, for endocavitary observations such as those
relating to vesica, stomach, rectum, uterus, plates of little sizes
must be fixed to little rings mounted on rods forming probes (not
shown).
FIg. 7 diagrammatically shows another modified embodiment useful
for surveying anfractuous surfaces. According to this variant a
plate 35 according to the present invention is fixed at its
periphery 36 to a plain transparent plate 37 and together with it
forms a sealed volume 38 which may be inflated through a valve 39.
The plate 35, this term being here to be interpreted in a broad
sense going beyond the concept of planar condition generally
associated with the term plate, is made of transparent synthetic
material. On its inner surface there are liquid crystals applied in
suspension in an elastic polymer.
By inflation a certain pressure is established in the volume 38 and
this makes the observation of anfractuous surfaces easier, the
plate 35 thus being fitted as much as possible to their shape. The
dichroism of said plate, is therefore observed through the
transparent plate 37. Of course, to this plate an arm may be fixed,
allowing to join a photographic camera as afore mentioned in
connection with the embodiments comprising a frame.
According to the variant shown in FIG. 8, which may be used alone
or jointly with any of the preceding embodiments, several sensitive
layers, for instance three layers 12, 12', 12" are juxtaposed as
parallel strips on the same support layer 10 with the interposition
(preferably but not necessarily) of a common heat guiding layer
which cannot be seen on the figure. The width of these bands or
layers 12, 12', 12" is in the range of 0.5 - 1 cm, and these layers
comprise liquid crystals having as a normal reference temperature,
values different from one another, offset between each other for
instance of 1.5.degree. C.
The contemporaneous observation of these layers, e.g., used for a
thermal survey of the lower limbs or of the forehead, allows an
immediate absolute measurement of the temperature of the surveyed
area. In fact, only that layer whose sensitivity range comprises
such temperature, changes to red. The number of sensitive bands may
be from two to five and even more.
Of course the present invention is not limited to the described and
illustrated embodiments, but comprises also any variant, more
particularly as to the nature of the material forming the support
layer which could be of the material marketed under the trade name
cellophane, of paper or of any of the materials used for
manufacturing magnetic tapes.
In any case this support layer will be preferably very thin in
order to avoid a lateral heat diffusion, and will be preferably a
good heat conductor so as to avoid a too long permanence of the
dichronic images obtained. Moreover, it has to be pointed out that
the sensitive layer 12 is preferably lacking of any surface
protective coating, and more particularly of any brilliant coating.
The layer is advantageously opaque, thus avoiding any inopportune
reflection during the photographic recording, more particulary when
using flash lamp.
* * * * *