Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02647747 2016-12-07
DEVICE FOR COUNTING AND DETERMINING THE DIRECTION OF
PASSAGE OF LIVING BEINGS
BACKGROUND OF THE INVENTION
The invention concerns a device for counting and determining the direction of
passage of living
beings. It finds its application in the field of counting and determining the
direction of passage of
persons on paths or in buildings. However, it can also apply to the counting
and determination of
the direction of passage of animals on paths.
FIG. 1 depicts a device for determining the direction of passage 100 of a
living being 114 of the
prior art, which comprises a pyroelectric cell 102 and a processing unit (not
shown).
The pyroelectric cell 102 is of the type comprising a first detection window
104 and a second
detection window 106 disposed, horizontally, alongside each other. The
pyroelectric cell 102 and
in particular the first detection window 104 and the second detection window
106 are sensitive to
infrared radiation, and the pyroelectric cell 102 delivers an electrical
signal 200 representing the
passage of the living being 114 in front of the detection windows 104 and 106.
The electrical
signal 200 is shown in FIG. 2a.
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The processing unit is connected to the pyroelectric cell 102 and receives the
electrical signal
200 thus delivered and, from the analysis of this electrical signal 200, it
determines the direction
of passage of the living being 114 in front of the device for determining the
direction of passage
100.
The parallelepipeds 110 and 112 of FIG. 1 represent the zones of influence of
the detection
windows 104 and 106. That is to say infrared radiation emitted inside the
first zone of influence
110 is perceived by the first detection window 104 and infrared radiation
emitted inside the
second zone of influence 112 is perceived by the second detection window 106.
The arrow 116 represents the direction of passage of the living being 114.
The electrical signal 200 represents the electrical signal delivered by the
pyroelectric cell 102
during the passage of the living being 114 in front of the pyroelectric cell
102. The arrow 210a
represents the direction of passage of the living being 114. In the example in
FIG. 2a, the arrow
210a repeats the direction of the arrow 116 in FIG. 1.
The maximum 202 represents the detection by the first detection window 104 of
the passage of
the living being 114 and the minimum 204 represents the detection by the
second detection
window 106 of the passage of the living being 114. The secondary minimum 206
and the
secondary maximum 208 represent the damping of the signal and depend on the
elements
making up the pyroelectric cell 102 and the processing unit.
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If the living being 114 moves in a direction opposite to that of the arrow
116, the electrical signal
200 is reversed, that is to say the signal passes first of all through the
minimum 204 representing
the passage of the living being 114 in front of the second detection window
106 and then a
maximum 202 representing the passage of the living being 114 in front of the
first detection
window 104. Such an electrical signal is depicted at FIG. 2b. The direction of
passage of the
living being 114 is then represented by the arrow 210b.
The determination of the direction of passage of the living being 114 in front
of the device for
determining the direction of passage 100 therefore seems to be able to take
place by analysis of
the electrical signal 200.
The problem with the device 100 of the prior art is that in fact, this
determination is accurate
only if the temperature of the living being 114 is greater than that of the
device for determining
the direction of passage 100.
This is because, if the temperature of the living being 114 is lower than that
of the device for
determining the direction of passage 100, the curves in FIGS. 2a and 2b are
reversed and there is
then a lack of determination of the direction of passage of the living being
114.
Thus, because of the reversal of the difference in temperature between the
living being 114 and
the device for determining the direction of passage 100, there arises
uncertainty with regard to
the direction of passage of the living being 114 in front of the device for
determining the
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direction of passage 100. Such a reversal in the difference in temperature may
exist when the
device for determining the direction of passage 100 is placed in a heated
corridor and the living
being 114 comes from a place where the temperature is lower, for example
outside, and his
garments are cold.
In addition, such a device for determining the direction of passage 100 does
not make it possible
to count the number of living beings 114 passing in front of it.
BRIEF SUMMARY OF THE INVENTION:
An object of the present invention is therefore to propose a device for
counting and determining
the direction of passage of living beings that does not have the drawbacks of
the prior art,
allowing counting of living beings as well as an exact determination of the
direction of passage
of the living beings.
To this end, there is proposed a device for counting and determining the
direction of passage of
living beings comprising: a first pyroelectric cell adapted to deliver an
electrical signal of a first
type representing the infrared radiation emitted by a living being passing in
front of said first
cell; a second pyroelectric cell of the type comprising a first detection
window and a second
detection window and adapted to deliver an electrical signal of a second type
representing the
direction of passage of the living being in front of said second pyroelectric
cell the first cell and
the second pyroelectric cell being one above the other; and a processing unit
adapted to
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determine firstly the number of living beings passing in front of said device,
by analysing the
electrical signal of the first type, and secondly the direction of passage of
the living beings
passing in front of said device by analysing the electrical signal of the
first type and the electrical
signal of the second type.
According to a particular embodiment, the first cell is a pyroelectric sensor
of the type
comprising a first detection window and a second obscured detection window.
According to a particular embodiment, the determination of the direction of
passage of the living
beings passing in front of said device consist of analysing the level of the
electrical signal of the
second type at the moment when the living being leaves the cone of influence
of the first
detection window of the first cell.
Advantageously, the device for counting and determining the direction of
passage comprises a
cylindrical Fresnel lens disposed in front of each cell.
Advantageously, for each cell, the position of the focus of the Fresnel lens
is such that the
infrared radiation emitted by each living being is focussed substantially
between the two
detection windows of the cell in question.
BRIEF DESCRIPTION OF THE DRAWINGS:
The characteristics of the invention mentioned above, as well as others, will
emerge more clearly
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from a reading of the following description of an example embodiment, the said
description
being given in relation to the accompanying drawings, among which:
FIG. 1 depicts a device for determining the direction of passage of a living
being of the prior art;
FIG. 2a and FIG. 2b depict curves representing the signal output from the
pyrotechnic cell of the
prior art;
FIG. 3 depicts a device for counting and determining the direction of passage
of a living being
according to the invention;
FIG. 4a, FIG. 4b, FIG. 4c and FIG. 4d are the various curves representing the
signal output from
the second pyroelectric cell of the device for counting and determining the
direction of passage
of a living being according to the invention;
FIG. 5a and FIG. 5b depict the curves representing the signal output from the
first cell of the
device for counting and determining the direction of passage of a living being
according to the
invention; and
FIGS. 6a, 6b, 6c and 6d depict the combination of curves representing the
signal output from the
second pyroelectric cell and the curves representing the signal output from
the first cell of the
device for counting and determining the direction of passage of a living being
according to a
particular embodiment of the invention.
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DETAILED DESCRIPTION OF THE INVENTION:
FIG. 3 depicts a device for counting and determining the direction of passage
500 of a living
being 114 according to the invention. The elements identical to the device for
determining the
direction of passage 100 of the prior art bear the same references.
Thus the device for counting and determining the direction of passage 500
according to the
invention comprises: a first cell 502 adapted to deliver an electrical signal
of a first type
representing the passage of a living being 114 in front of the first cell 502;
a second pyroelectric
cell 102 of the type comprising a first detection window 104 and a second
detection window 106
and adapted to deliver an electrical signal of a second type representing the
direction of passage
of the living being 114 in front of the second pyroelectric cell 102; and a
processing unit adapted
to determine firstly the number of living beings passing in front of the
device 500 by analysing
the electrical signal of the first type and secondly the direction of passage
of the living beings
114 passing in front of the device 500 by analysing the electrical signal of
the first type and the
electrical signal of the second type.
According to a particular embodiment of the invention depicted in FIG. 3, the
first cell 502 is a
pyroelectric sensor 502 of the type comprising a first detection window 504
and a second
obscured detection window.
In FIG. 3, the first cell 502 and second cell 102 are disposed close to each
other and one above
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the other.
The detection windows 104, 106 and 504 are oriented vertically and the
detection windows 104
and 106 of the second cell 102 are disposed, horizontally, one alongside the
other.
So that the vision angle of each cell 102, 502 is not too extensive and
therefore that each cell
102, 502 is solely influenced by a single living being 114 passing in front of
the device 500, the
latter comprises, for each cell 102, 502, a cylindrical Fresnel lens 508
disposed in front of each
cell 102, 502. Advantageously, for each cell 102, 502, the position of the
focus of the Fresnel
lens 508 is such that the infrared radiation emitted by the living being 114
is focussed
substantially between the two detection windows 104, 106, 504 of the cell 102,
502 in question.
The cone 506 represents the cone of influence of the first cell 502 and in
particular of the first
detection window 504 of the first cell 502, that is to say any living being
114 entering this cone
506 is seen by the first cell 502.
The cone 510 represents the cone of influence of the second cell 102, that is
to say any living
being 114 entering this cone 510 is seen by the second cell 102 and in
particular by the first
detection window 104 and the second detection window 106.
To allow better detection of each living being 114 passing the device 500, and
to avoid the
passage of a plurality of living beings 114 being analysed as the passage of
single living being
114, the angle of each cone of influence 506, 510 is reduced to the maximum
possible extent.
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In addition, the fact that the first cell 502 and the second cell 102 are
disposed one above the
other makes it possible to align the cone 506 and the cone 510 vertically.
Thus a single living
being 114 influences simultaneously the first cell 502 and the second cell 102
and, when the
living being 114 leaves one of the cones 506 or 510, it also leaves the other
cone 510 or 506.
Thus, when the living being 114 no longer influences one of the cells 502 or
102, it no longer
influences the other cell 102 or 502 respectively, which avoids faulty
counting or faulty
determination of the direction of passage.
This particular arrangement also makes it possible to obtain a compact device
for counting and
determining the direction of passage 500.
FIG. 5a and FIG. 5b depict the curves representing the signal output from the
first cell 502 of the
device for counting and determining the direction of passage 500, that is to
say the electrical
signal of the first type.
FIG. 5a depicts the curve 602 when the external surfaces of the living being
114 are at a
temperature lower than that of the device 500. The curve 602 has a maximum
that corresponds to
the passage of the living being 114 in the cone of influence 506, then an
abrupt variation (here a
drop) corresponding to the fact that the living being 114 leaves the cone of
influence 506, and
then a return to the initial level.
FIG. 5b depicts the curve 604 when the external surfaces of the living being
114 are at a
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temperature greater than that of the device 500. The curve 604 has minimum
that corresponds to
the passage of the living being 114 in the cone of influence 506, and an
abrupt variation (here a
rise) corresponding to the fact that the living being 114 leaves the cone of
influence 506, and
then a return to the initial level.
The processing unit can thus, by analysing the signal received from the first
cell 502, count the
number of living beings 114 passing in front of the device 500 by incrementing
a counter. In
fact, in order to count a living being 114, the processing unit analyses the
electrical signal of the
first type and increments the counter when it detects a first variation (rise
602 or fall 604) from
the initial level, and then a second variation in a direction opposite to the
first variation (fall or
rise).
From the analysis of the signal received from the first cell 502, the
processing unit can thus
determine whether the temperature of the living being 114 is less than or
greater than that of the
device 500. The first cell 502 therefore fulfils a role of counting and
temperature sensing cell that
delivers an electrical signal representing the difference in temperatures
between the device 500
and the living being 114.
FIGS. 4a, 4b, 4c and 4d are the curves 310a, 310b, 410a and 410b representing
the signal output
from the second pyroelectric cell 102 of the device for counting and
determining the direction of
passage of a living being 500, that is to say the electrical signal of the
second type. These curves
310a, 310b, 410a and 410b have a less sharp profile than the curves 602 and
604 because they
result from a combination of the electrical signals coming from the first
detection window 104
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and the second detection window 106 of the second cell 102. In particular, the
zone of return to
the initial value of each of these curves 310a, 310b, 410a and 410b is
disturbed.
The curve 310a represents the passage of a living being 114 whose temperature
is less than that
of the device 500 in a first direction represented by the arrow 300a.
The curve 310b represent the passage of a living being 114 whose temperature
is less that that of
the device 500 in a second direction represented by the arrow 300b.
The curve 410a represents the passage of a living being 114 whose temperature
is greater than
that of the device 500 in the first direction represented by the arrow 400a,
which is identical to
the direction of the arrow 300a.
The curve 410b represents the passage of a living being 114 whose temperature
is greater than
that of the device 500 in the second direction represented by the arrow 400b,
which is identical to
the direction of the arrow 300b.
The analysis, by the processing unit, of the signal of the first type and of
the signal of the second
type thus makes it possible to determine the direction of passage of the
living being 114 in front
of the device 500.
The curve 310a has a maximum 302 that corresponds to the passage of the living
being 114 in
front of the first detection window 104 and then an abrupt drop and a minimum
304 that
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corresponds to the passage of the living being 114 in front of the second
detection window 106,
then an abrupt rise that corresponds to the fact that the living being 114
emerges from the cone of
influence 510, and then a return to the initial level.
The curve 310b has an arrangement reversed with respect to the curve 310a,
that is to say it has
the minimum 304 that corresponds to the passage of the living being 114 in
front of the second
detection window 106, then an abrupt rise and the maximum 302 that corresponds
to the passage
of the living being 114 in front of the first detection window 104, then an
abrupt drop that
corresponds to the fact that the living being 114 leaves the cone of influence
510, and then a
return to the initial level.
The curve 410a has a minimum 402 that corresponds to the passage of the living
being 114 in
front of the first detection window 104, then an abrupt rise and a maximum 404
that corresponds
to the passage of the living being 114 in front of the second detection window
106, then an
abrupt drop that corresponds to the fact that the living being 114 emerges
from the cone of
influence 510, and then a return to the initial level.
The curve 410b has an arrangement reversed with respect to the curve 410a,
that is to say it has
the maximum 404 that corresponds to the passage of the living being 114 in
front of the second
detection window 106, then an abrupt fall and the minimum 402 that corresponds
to the passage
of the living being 114 in front of the first detection window 104, then an
abrupt rise that
corresponds to the fact that the living being 114 leaves the cone of influence
510, and then a
return to the initial level.
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As described above, apart from the electrical signal of the second type
delivered by the second
pyroelectric cell 102 and representing the direction of passage of the living
being 114 in front of
the detection windows 104 and 106, the processing unit receives the electrical
signal of the first
type delivered by the first cell 502 and representing the passage of the
living being 114 in front
of the detection window 504. Thus the processing unit receives both one of the
electrical signals
of the first type, depicted in FIG. 5a or 5b, and one of the electrical
signals of the second type,
depicted in FIGS. 4a, 4b, 4c or 4d.
After analysis of the electrical signal of the first type (FIG. 5a, FIG. 5b),
received from the first
cell 502, the processing unit determines whether the temperature of the living
being 114 is
greater than or less than that of the device for counting and determining the
direction of passage
500.
Analysis of the electrical signal of the second type then makes it possible to
determine the
direction of passage of the living being 114. In fact the determination of the
temperature of the
living being 114 compared with that of the device for counting and determining
the direction of
passage 500 limits the analysis to two of the four curves depicted in FIGS.
4a, 4b, 4c and 4d.
If the temperature of the living being 114 is less than that of the device for
counting and
determining the direction of passage 500, the direction of passage of the
living being 114 is
given by the arrow 300a in FIG. 4a, or by the arrow 300b in FIG. 4b. If the
signal of the second
type is similar to the curve in FIG. 4a, that is to say the curve passes first
of all through the
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maximum 302 and then through the minimum 304, then the direction of passage is
given by the
arrow 300a. If the signal of the second type is similar to the curve in FIG.
4b, that is to say the
curve passes first of all through the minimum 304 then through the maximum
302, then the
direction of passage is given by the arrow 300b.
If the temperature of the living being 114 is greater than that of the device
for counting and
determining the direction of passage 500, the direction of passage of the
living being 114 is
given by the arrow 400 of FIG. 4c, or by the arrow 400b in FIG. 4d. If the
signal of the second
type is similar to the curve in FIG. 4c, that is to say the curve passes first
of all through the
minimum 402 and then through the maximum 404, then the direction of passage is
given by the
arrow 400a. If the signal of the second type is similar to the curve in FIG.
4d, that is to say the
curve passes first of all through the maximum 404 and then through the minimum
402, then the
direction of passage is given by the arrow 400b.
The various combinations between the signal of the second type output from the
second
pyroelectric cell 102 and the signal of the first type output from the first
cell 502 of the device
for counting and determining the direction of passage of a living being 500,
are represented by
the curves in FIGS. 6a, 6b, 6c and 6d.
Thus knowledge of the temperature of the living being 114, compared with that
of the device for
counting and determining the direction of passage 500, makes it possible to
determine precisely
the direction of passage of the living being 114.
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As described above, the processing unit is adapted to count the number of
living beings 114 who
have passed in front of the device 500. According to a particular embodiment,
the processing
unit counts, in a first register, the number of living beings 114 who have
passed in the direction
of the arrows 300a and 400a and, in a second register, the number of living
beings 114 who have
passed in the direction of the arrows 300b and 400b.
For FIGS. 6a, 6b, 6c and 6d, the first cell 502 and the second cell 102 are
disposed one above the
other, and the first detection window 504 of the first cell 502 is disposed
substantially on the
same vertical axis as the first detection window 104 of the second cell 102.
FIG. 6a depicts the passage of a living being 114 whose external temperature
is less than that of
the device for counting and determining the direction of passage 500, and
which passes in front
of the said device 500 in the direction represented by the arrow 300a.
The living being 114 thus first of all passes in front of the first detection
window 504, 104 of
each cell 502, 102 generating a first maximum 702 on the curve 602 and the
second maximum
302 on the curve 310a. During the forward movement of the living being 114,
the influence of it
is felt at the second detection window 106 of the second cell 102, represented
here by the drop
between the maximum 302 and the minimum 304. The minimum 304 then represents
the
moment when the living being 114 influences mainly the second detection window
106 of the
second cell 102. During this passage from the maximum 302 to the minimum 304,
the living
being 114 leaves the cone of influence 506 of the first detection window 504,
which generates a
rapid variation (here a drop) in the signal delivered by the first cell 502.
At the end of the rapid
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variation, the curve 310a, representing the signal of the second type, is at
the minimum 304, that
is to say the living being 114 is situated in front of the second detection
window 106 of the
second cell 102. Thus the determination of the direction of passage of the
living being 114
passing in front of the device 500 can be determined by analysing the level of
the electrical
signal of the second type, at the moment when the living being 114 leaves the
cone of influence
506 of the first detection window 504 of the first cell 502.
FIG. 6b represents the passage of a living being 114 whose external
temperature is less than that
of the device for counting and determining the direction of passage 500 and
that passes in front
of the said device 500 in the direction represented by the arrow 300b.
FIG. 6c represents the passage of a living being 114 whose external
temperature is greater than
that of the device for counting and determining the direction of passage 500
and passes in front
of the said device 500 in the direction represented by the arrow 400a.
FIG. 6d represents the passage of a living being 114 whose external
temperature is greater than
that of the device for counting and determining the direction of passage 500
and who passes in
front of the said device 500 in the direction represented by the arrow 400b.
FIGS. 6b, 6c and 6d are equivalent to FIG. 6a, and each shows the variations
in the electrical
signal of the second type which are coordinated with those of the electrical
signal of the first
type. In particular, when the living being 114 leaves the cone of influence
506 of the first
detection window 504, this generates a rapid variation (a drop or rise) in the
signal delivered by
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the first cell 502 and, at the end of this rapid variation, the curve
representing the electrical signal
of the second type 310b, 310c and 310d is at the minimum 402 or maximum 302,
404, that is to
say the living being 114 is situated in front of the second detection window
106 of the second
cell 102 or in front of the first detection window 104 of the second cell 102.
Thus, in general terms, the determination of the direction of passage of the
living being 114
passing in front of the device 500 consists of analysing the level of the
electrical signal of the
second type at the moment when the living being 114 leaves the cone of
influence 506 of the first
detection window 504 of the first cell 502. In other words, when the thermal
mass represented by
the living being 114 leaves the cone of influence 506 of the first detection
window 504 of the
first cell 502, the signal of the first type and also its representative curve
602 or 604 have a rising
or falling edge that is sharp and very short in time. This instant then
represents a remarkable
event. Analysis of the signal of the second type of this instant makes it
possible to determine the
direction of passage of the living being 114.
Naturally the present invention is not limited to the example and embodiment
described and
depicted but is capable of many variants accessible to persons skilled in the
art.
For example, the various curves may be different according to the
characteristics of the cells
used and the characteristics of the electronic components constituting the
processing unit. In
particular the directions of variation may be reversed.
The curves may also be different if the first detection window of the first
cell is aligned vertically
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with the second detection window of the second cell. However, there always
exists a
correspondence between the moment when the living being 114 no longer
influences the first
detection window of the first cell and the level of the electrical signal of
the second type.
Although the invention is more particularly described in the case where the
first detection
window 504 of the first cell 502 is vertical, the invention can also function
in the case where this
detection window 504 is oriented horizontally.
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