The invention relates to a motor-driven roller blind comprising, on the one hand, an apron rolling up onto and unrolling from a winding shaft inside which is accommodated a tubular-type driving gear-motor and, on the other hand, means providing an electrical signal representative of the movement of the apron and an electrical-signal processing unit capable of acting on the running of the driving gear-motor, viz. to control the stopping of same in the event an obstacle is present. As a matter of fact, said means providing an electrical signal representative of the movement of the apron are comprised of at least one inductive sensor extending at least partly along the path followed by the apron, this inductive sensor being capable of creating an electromotive force under the action of the passing of a permanent magnet associated with the lower portion of the apron, which electromotive force is detected by the processing unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a motor-driven roller blind comprising an apron 
formed by a juxtaposition of slats at least hingedly joined to each other 
and the ends of which move in side slides, this apron rolling up onto and 
unrolling from a winding shaft inside which is accommodated a tubular-type 
driving gear-motor. This roller blind may eventually also be provided with 
means providing an electrical signal representative of the movement of the 
apron and an electrical-signal processing unit capable of acting on the 
running of the driving gear-motor, viz. to control the stopping of same in 
the event an obstacle is present. 
This invention will find its application in the field of the closing 
devices, such as roller blinds. 
2. Description of the Prior Art 
There is already known a roller blind corresponding to the above 
description. Thus, this motor-driven roller blind comprises an apron 
rolling up onto or unrolling from a winding shaft which is in this case 
rotatingly driven by tubular-type electric driving means, viz. a 
gear-motor, which is as a matter of fact accommodated inside the winding 
shaft. It should be noticed that this winding mechanism for the apron of 
the roller blind is generally arranged in a box under which extend slides 
serving for guiding the side ends of the slats the apron of comprised of, 
this during unrolling or rolling up of this latter. 
This roller blind is also provided with means providing an electrical 
signal representative of the movement of the apron, these means being 
substantially comprised of a pulley onto which is wound a flexible member, 
such as a cord, the free end of which is connected to the end slat of the 
apron. Thus, during unrolling of this apron, this gives rise to the 
unwinding of the cord and the driving of said pulley. Associated with this 
latter are springy means ensuring the re-winding of the cord onto the 
pulley during the rolling up of the apron. There is also provided a signal 
generator mechanically connected to the spindle of the pulley and 
providing an electric voltage representative of the speed of rotation of 
the pulley. It is specified that this signal generator may preferably be 
in the shape of a Hall effect sensor, such as a synchronous motor used as 
a generator. According to another embodiment, there is also foreseen to 
use as signal generator a constraint gauge combined with a spring 
gradually tensioned by the rotation of the pulley. 
In addition, there should be noticed the presence, at the level of this 
roller blind, of a logical processing unit capable of operating in 
learning mode and working mode, by sampling, and comprising means for 
storing, in learning mode, the value samples corresponding to the measured 
signal samples and means for comparing, in working mode, the stored value 
samples to value samples obtained in working mode. Thus, this logical unit 
comprises means for sampling the electric signal provided by the signal 
generator. 
As a matter of fact, the main disadvantages experienced with a roller blind 
as described above are mainly due to the structure of the means providing 
an electrical signal representative of the movement of the apron. More 
particularly, such means are first of all bulky as far as they require the 
installation, at the level of the box of the roller blind, of a pulley 
onto which is capable of rolling up the transmission member formed by the 
cord. Furthermore, with that pulley should be associated the signal 
generator in the shape of a synchronous motor. As a matter o fact, this 
unit is positioned at the end of the winding shaft of the apron, which is 
not always feasible, due to lack of space. 
In addition, the mechanical connection between the end slat of the apron 
and the pulley is a cause for operating trouble. Viz., the cord forming 
this transmission member can at any time get jammed through clamping 
either at the level of the roller blind itself or at the height of the 
door or window closed by this roller blind. Not taking into consideration 
that this cord is accessible to the user, which obviously increases the 
risks of incidents. 
There is furthermore known a roller blind which uses, as means providing an 
electrical signal representative of the movement of the apron, first of 
all means for detecting the linear translation motion of the apron, in the 
shape of a roller rubbing against the surface of said apron and converting 
the linear displacement motion of the blind into a rotary motion. 
Furthermore, there are provided coding means, in the shape of a coding 
wheel provided with a number of peripheral and radial notches which is 
integral with said friction roller and driven by this latter. Associated 
with this coding wheel is a system for detecting the information provided 
by this latter, viz. an optoelectronic sensor, which is capable of 
detecting the passing of the notches of said coding wheel and providing an 
electrical signal. This latter is then processed at the level of a central 
processing unit. 
There is also provided a roller blind apron sensor for detecting its 
arrival in the upper position. This sensor is carried out as a 
spring-pulled roller resting onto the surface of the apron and leaving 
this surface at the upper travel end in order to operate a microcontact 
controlling the stopping of the apron driving gear-motor. 
It is foreseen to arrange such means providing an electrical signal 
representative of the movement of the apron at the upper end of a side 
slide or even at the supper end of each side slide a roller blind is 
provided with. 
Although such means capable of providing an electrical signal 
representative of the movement of the apron are particularly bulky like 
those described first above, this is not their major disadvantage. They 
are indeed in no way adapted to roller blinds the apron of which is 
comprised of slats which are not only hingedly joined to each other, but 
also telescopic, so that the possibility exists of obtaining an openwork 
position as is the case in most domestic roller blinds. The roller rubbing 
against the surface of said apron is indeed necessarily arranged at the 
upper end of this latter. Hence, it can detect a change in the movement of 
this apron only when all the slats located under this roller have been 
piled up and tightened against each other. 
In addition, in this case one also finds the mechanical connection which is 
indispensable between the means providing an electrical signal 
representative of the movement of the apron and this latter. Now, such a 
mechanical connection is liable to dysfunctions, viz. in the course of 
time, which cannot be accepted for a product, such as a roller blind, with 
a long lifetime. 
SUMMARY OF THE INVENTION 
The object of this invention is to cope with all the disadvantages 
experienced with the state of technique as described above, this by means 
of motor-driven roller blind of a simple design, while being particularly 
sure as regards both lifetime and safety itself. 
To this end, the invention relates to a motor-driven roller blind 
comprising, on the one hand, an apron formed by a juxtaposition of slats 
at least hingedly joined to each other and the ends of which move in side 
slides, this apron rolling Lip onto and unrolling from a winding shaft 
inside which is accommodated a tubular-type driving gear-motor and, on the 
other hand, means providing an electrical signal representative of the 
movement of the apron and an electrical-signal processing unit capable of 
acting on the running of the driving gear-motor, viz. to control the 
stopping of same in the event an obstacle is present, said means providing 
an electrical signal representative of the movement of the apron being 
comprised of at least one inductive sensor extending at least partly along 
the path followed by the apron, this inductive sensor being capable of 
creating an electromotive force under the action of the passing of a 
permanent magnet associated with the lower portion of the apron. 
The advantages achieved thanks to this invention mainly reside in that one 
can be free of any mechanical connection between the apron of the roller 
blind and any fixed member located at the level of this latter. In 
addition, the immobilizing of the apron by an obstacle can be noticed 
right from the jamming of the last slats the lower portion of this apron 
is comprised of. 
In addition, the control of the movement of the apron is effected 
constantly and not discontinuously. This allows to more easily detect a 
change in the operation of the roller blind, e.g., due to the presence of 
an obstacle. This results into a less complex and, accordingly, less 
expensive processing unit. In this respect, this simplicity of design is 
to be found at the level of all these means capable of providing an 
electrical signal representative of the movement of the apron. It should 
viz. be noticed that they may advantageously form control means for 
stopping the running of the gear-motor at the upper and lower travel end 
of the apron. More particularly, it can be foreseen that the permanent 
magnet, when arriving at the upper or lower travel end, withdraws in the 
presence of the inductive sensor, at the upper or lower end of this 
latter, causing the gear-motor to stop. 
Moreover, it should be noticed that the very adjunction of a permanent 
magnet, viz. to one of the slats the lower portion of this apron is 
comprised of, allows to contemplate even in another way an easy control of 
this stopping the running of the driving gear-motor. Viz., such a 
permanent magnet may advantageously form the remote control means for a 
switch placed at the lower portion and at the upper portion of a slide, 
such as a flexible leaf switch (FLS) or an inductive sensor. Thus, when 
unrolling the apron, the passing of the permanent magnet associated with 
this latter in front of a flexible leaf switch or such inductive sensor 
located at the lower portion of the slide causes, either immediately or in 
a delayed manner, the stopping of the driving gear-motor. This also 
applies to the rolling up and when the permanent magnet passes in front of 
the switch located at the upper end of the slide. 
In this respect, the invention also relates to a motor-driven roller blind 
comprising, on the one hand, an apron formed by a juxtaposition of slats 
at least hingedly joined to each other and the ends of which move in side 
slides, this apron rolling up onto and unrolling from a winding shaft 
inside which is accommodated a tubular-type driving gear-motor, one slat 
forming the lower portion of the apron being provided with remote control 
means, such as a permanent magnet, flexible leaf switch (FLS)-type 
switches or inductive sensors capable of controlling, either directly or 
through a suitable processing unit, the stopping of the running of the 
driving gear-motor when the apron arrives at the lower travel end and at 
the upper travel end.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As appears in the Figures of the attached drawing, this invention relates 
to a motor-driven roller blind 1; this latter includes an apron 2 formed 
by a juxtaposition of slats 3, at least hingedly joined to each other. As 
a matter of fact, these slats 3 are very often also telescopic with 
respect to each other, so that the apron can adopt an openwork position 
which just corresponds to keeping these slats 3 separated from each other. 
This apron 2 rolls up onto or unrolls from a winding shaft 4 generally 
rotatingly mounted into a box topping the opening provided in a building 
construction which has to be closed by means of this motor-driven roller 
blind 1. Inside this winding shaft 4 is accommodated a tubular-type 
driving gear-motor 5. 
It should be noticed that when controlling the rolling up or the unrolling 
of the apron 2, the ends 6 of the slats 3 move in side slides 7. These 
latter are usually positioned at the level of the vertical sides of a door 
or window recess or even on the outer face of the stiles of the sash-frame 
of a door, French window or the like. 
This motor-driven roller blind 1 is in addition provided with means 8 
capable of providing an electrical signal representative of the movement 
of the apron 2 as well as with a unit 9 for processing this electrical 
signal capable of acting on the running of the driving gear-motor 5, e.g. 
to control the stopping of this latter in the event an obstacle is present 
on the path of the apron 2. 
There should indeed be avoided that such an obstacle placed on the path of 
the apron 2 of the motor-driven roller blind 1 leads to an incident at the 
level of the operation of this motor-driven roller blind 1 or to any 
accident whatsoever. Thus, according to the invention, these means 8 which 
are capable of providing an electrical signal representative of the 
movement of the apron 2 are comprised of at least one inductive sensor 10 
extending at least partly along the path followed by the apron 2, viz. 
along a side slide 7, so that it be capable of creating an electromotive 
force under the action of the passing in front of this inductive sensor 10 
of a permanent magnet 11 associated with the lower portion 12 of the apron 
2. This electromotive force produced by the inductive sensor 10 is of 
course inexistent in the absence of any motion of the permanent magnet 11 
and, accordingly, of the apron 2. Furthermore, it is positive within the 
framework of the movement of the apron in one direction and negative when 
this apron 2 moves in the opposite direction. 
Thus, through the processing unit 9, there is proceeded to the control and 
the checking of the existence of an electromotive force produced by the 
inductive sensor 10. More particularly, this processing unit 9 ensures the 
stopping of the running of the driving gear-motor 5 as soon as it detects 
the passing of a current through this driving gear-motor 5 and the absence 
of voltage at the terminals of the inductive sensor 10. In addition, this 
processing unit 9 may have as a function to stop the running of the 
driving gear-motor 5 if during the unrolling of the apron 2 there is 
detected a reversal of the electromotive force and, accordingly, of the 
voltage at the terminals of the inductive sensor 10 without this reversal 
being due to a control of reversal of the motion of the apron 2 through a 
voluntary action of the user onto actuation means 13 such a motor-driven 
roller blind 1 is systematically fitted with. 
According to a preferred embodiment of the invention, the inductive sensor 
10 is in the shape of an inductance coil the terminals of which are 
connected to the processing unit 9 and which is wound onto a magnetic 
support 14, more particularly an hollow metal tube with a small 
cross-section. This cross-section of the magnetic support 14 is 
advantageously reduced to such an extent that this inductive sensor 10 can 
be positioned inside a slide 7 while authorizing the moving inside this 
latter of the ends 6 of the slats 3 the apron 2 is comprised of. In this 
respect, it should be noticed that a slide 7 is in the shape of profile 
with a U-shaped cross-section comprising an outer wall 15, an inner wall 
16 and a bottom 17. Very often, the outer 15 and inner 16 walls include, 
on their sides 18 facing each other, sealing brushes 19 having a thickness 
20 determining the maximum cross-section the inductive sensor 10 may 
adopt. 
According to another embodiment, this inductive sensor 10 is installed on 
the bottom 17 of the slide 7. 
The advantages resulting from such an arrangement of the inductive sensor 
10 inside a slide 7 reside in that said sensor is perfectly protected 
against voluntary or involuntary external aggressions. Thus, it is viz. 
difficultly accessible by a user. 
As regards the permanent magnet 11, of the type made of anisotropic 
ferrite, it is installed inside and at the end 6, in front of an inductive 
sensor 10, of a slat 3 the lower portion 12 of the apron 2 is comprised 
of. As a matter of fact, it is advantageous to install this permanent 
magnet 11 in the last slat 3A or the last but one slat 3B of the apron 2. 
Furthermore, there is advantageously foreseen to fit the inductance coil, 
at its lower portion 21, with a larger number of windings with a view to 
obtaining an electrical signal of a greater amplitude, in order to control 
the arrival at the lower travel end of the apron 2 and to allow a complete 
closing of the motor-driven roller blind 1. 
It is of course possible to install such an inductive sensor 10 in each of 
the slides 7 of the motor-driven roller blind 1, this in order to more 
rapidly detect the presence of an obstacle located on the path of the 
apron 2, while being sidely offset with respect to the vertical median 
plane of same, so that there is a phase shift between the jamming of one 
end of the slats 3 and the other end. 
It should be noticed that such means 8 capable of providing an electrical 
signal representative of the movement of the apron 2 according to the 
invention in addition allow a simplification of the control of the running 
of the driving gear-motor 5, viz. for controlling the stopping of same 
either when the apron 2, when unrolled, arrives at the lower travel end 
or, when rolled up, arrives at the upper travel end. Viz., the length of 
the inductive sensor 10 may be determined so that when it is no longer 
under the action of the permanent magnet 11 the processing unit 9 detects 
an absence of electromotive force and, accordingly, the arrival at the 
upper position and/or the lower position of the apron 2. Then the stopping 
of the driving gear-motor 5 is controlled, this either immediately or in a 
delayed way. 
As a matter of fact, this control of the running of the driving gear-motor 
5 is simply made easier through the mere presence of the permanent magnet 
11 at the level of the lower portion 12 of the apron 2. Such a permanent 
magnet 11 can indeed advantageously form the remote control means for 
switches 22, 23 of the flexible leaf switch (FLS) type or Reed bulbs to 
cause the stopping of the running of the driving gear-motor 5 when the 
apron 2 is unrolled and at the lower travel end or rolled up and at the 
upper travel end. More particularly, such switches 22, 23 are, in these 
circumstances, installed either on a slide 7 or inside this latter, so 
that the running of the driving gear-motor 5 is stopped at the passing of 
the permanent magnet 11 e.g. the end 6 of one slat 3A, 3B is provided 
with. According to another embodiment, the switches 22, 23 capable of 
being controlled through the permanent magnet 11 placed on the apron 2 may 
be formed by inductive sensors connected to the processing unit 9. Thus, 
as soon as this latter detects an electrical signal of a given, positive 
or negative, intensity and sign at the terminals of one of these inductive 
sensors, it controls the stopping of the running of the driving gear-motor 
5, since this corresponds to the arrival of the apron at the lower travel 
end or at the upper travel end. In order to better understand the 
invention through clearer drawings, the flexible leaf switch-type switches 
22, 23 or inductive sensors have been shown, in FIG. 1, in the slide 
opposite the one accommodating the inductive sensor 10. They may however 
be associated with the same slide 7 as this latter, viz. in order to avoid 
the installing of a second permanent magnet in a slat of the apron 2. 
Of course, like for the inductive sensors at the terminals of which there 
not only must be detected an electrical signal, but the positive or 
negative sign of this latter has also to be taken into consideration in 
the case of flexible leaf switches or Reed bulbs, only one of them is 
active according to the direction of rotation imparted to the winding 
shaft 4. Thus, only the Reed bulb 22 arranged at the bottom of the slide 7 
is capable of stopping the driving gear-motor 5 when controlling the 
unrolling of the apron 2. On the contrary, only the Reed bulb 23 arranged 
at the top of the slide 7 can control the stopping of the running of the 
driving gear-motor 5 when the apron arrives in the upper position, rolled 
up about the winding shaft 4. 
It should be noticed that these switches 22, 23 thus controlled by a 
permanent magnet 11, irrespective of their technology, allow a precision 
at the level of the travel ends which hitherto was controlled by a system 
of storing, and thus deriving, without taking into consideration the 
actual situation, i.e. the actual position of the apron when controlling 
these travel ends. 
When reading the description above, one understands very well that this 
invention not only provides actual solutions to the problems experienced 
in this field over the past, but, in addition, allows to simplify the 
design of the motor-driven roller blinds. In particular, the means 
intended for providing an electrical signal representative of the movement 
of the apron are easy to make and of a negligible size. They are however 
particularly reliable, since they are insensitive to aggressions from 
outside. 
In addition, the association of a permanent magnet with the apron allows a 
particularly simplified control of the running of the driving gear-motor 
which, accordingly, proves less complex.