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FIELD OF THE INVENTION 
     The present invention relates to a device for driving a closing or sun-protection screen, as well as to a closure or sun-protection installation incorporating such a device. 
     A closure installation is understood to mean structures having openings that are closed or covered by doors, blinds, shutters and equivalent devices. 
     BACKGROUND OF THE INVENTION 
     In an installation having an opening, a screen, which may be a supple screen body or a rigid or semi-rigid panel, is displaced opposite the opening in order to selectively obturate the latter. In order to make the movement of the screen automatic, it has been proposed in the past to equip it with means for automatically detecting a position and/or a displacement of the screen and thus to use pre-defined positions to control electrical power supply to a screen drive motor, particularly the top and bottom ends of stroke and possibly intermediate positions in which the electrical supply to the motor is interrupted or modified in order to stop the screen or vary its speed and/or its drive torque. 
     An example of such an automatic drive device is given in FR-A-2 654 229. 
     Although the afore-mentioned device is satisfactory as to its function of automatic control of the drive of the screen, it presents a drawback concerning its tightness or sealing of components, particularly the tightness or sealing of the electronic processing unit that it contains with respect to the ambient environment. In effect, this type of device is likely to be installed outside and thus to be subjected to bad weather. This results in considerable risks of water infiltrating inside the tube and therefore reaching the electronic processing unit and the electric motor, particularly via the opening necessary for the kinematic links between a transmission means and a ring that rotatably supports the tube. It is difficult to seal this opening tight due to the mobility of the ring which, in addition, must present axial and radial clearances sufficient in order, on one hand, to match winding tubes of various origins whose dimensions are imprecise due to their mode of manufacture and, on another hand, to compensate for clearances of expansion associated with the functioning of the motor and climatic conditions. 
     In order to overcome this problem, one or more O-rings may be interposed between the ring and the fixed head and it may be attempted to adjust the ring around the fixed head as best possible. Furthermore, as described in EP-A-0 965 724, a ring of magnets of alternate polarities may be mounted around a circular support. These solutions are not economical as they require more voluminous parts, particular geometries at the level of the elements in contact and/or a complex process of assembly. In the device known from EP-A-0 965 724, the ring of magnets is expensive and the precision of measurement depends on the angular deviation between the peripheral magnets. This deviation being fixed by the diameter of the support which depends on the type of motor used, it cannot be adjusted easily. 
     In the domain of automatically controlled electric motors, U.S. Pat. No. 4,952,830 proposes embedding in an appropriate resin electronic sensors for detecting the displacement of the rotor of a motor, these sensors being kinematically linked to the stator. The tightness of the sensors is thus ensured but this solution does not guarantee tightness of the conductors connecting the sensors to an electronic unit for processing the signals furnished by these sensors. In other words, the potential problems of tightness do not affect the sensors as such but concern the more remote electronic components of the processing unit. 
     It is an object of the present invention to propose a device of the afore-mentioned type, in which the parts of the device sensitive to water are efficiently protected, particularly the electronic components of this device. 
     SUMMARY OF THE INVENTION 
     To that end, the invention relates to a device for driving a closing or sun-protection screen that includes a gear motor unit mounted within a winding tube for displacing the screen and which is controlled in rotation about an axis by the gear motor unit. A head is fixedly mounted on a bearing structure and supports the winding tube, a rotatable part having elements that are representative of a position and/or a displacement of the tube and which part is kinematically linked to rotate with the tube by mechanical transmission means, and sensor means for detecting the position and/or the displacement of the part. The sensor means is connected to an electronic processing unit adapted to determine the position and/or the displacement of the tube. A partition secured to and extending from the head defines, on one side, a first compartment for receiving at least the rotatable part and, on another side, a second compartment for receiving at least the electronic processing unit. The partition effectively seals the electronic processing unit from the rotatable part and thus the ambient environment. 
     The tightly sealed partition of the device according to the invention makes it possible hermetically to define respective hollow housings for the mobile part having elements representative of the position and/or the displacement of the tube and for at least the electronic processing unit that is sensitive to humidity and water coming from outside the device. This partition is secured to or integral with the head fixed with respect to the bearing structure. Such a structure does not complicate assembly and installation of the device. 
     Other characteristics of this device, taken separately or in all technically possible combinations, are set forth in claims  2  to  9 . 
     The invention also relates to a closure or sun-protection installation which comprises a screen adapted to be driven by a device as defined hereinabove. 
     Such an installation is economical, reliable and long-lasting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be more readily understood on reading the following description given solely by way of example and made with reference to the accompanying drawings, in which: 
         FIG. 1  schematically shows a partial longitudinal section of an installation according to the invention. 
         FIGS. 2 and 3  are plane sections along arrows II-II and III-III indicated in  FIG. 1 . 
         FIG. 4  is a view in perspective of a part of the installation of  FIG. 1 ; and 
         FIGS. 5 and 6  illustrate a variant of the drive device according to the invention,  FIG. 6  being in part a section along plane VI-VI indicated in  FIG. 5 . 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, the installation of  FIG. 1  comprises a closing or sun-protection screen E, intended to be selectively wound around a substantially horizontal tube T of axis X-X fixed with respect to the masonry of a fixed structure S in which is made an opening O to be obturated with the screen E. The winding tube T constitutes a member for displacement of the screen E and is mounted on a device  1  for reversible drive of the screen E. 
     This device  1  comprises a head  2  rigidly mounted on the masonry of the structure S. As shown in  FIGS. 1 to 4 , this head  2  comprises a solid base  4  in the form of a disc centered on axis X-X and mounted on the masonry and, on the side opposite the structure S, an annular skirt  6  centered on axis X-X. 
     For convenience, the term “front” in the following description will mean “directed towards the masonry”, i.e. directed towards the left in  FIG. 1 , while the term “rear” corresponds to the opposite direction. Moreover, for reasons of visibility, the skirt  6  is shown in solid lines in  FIG. 4 , while, in this view, the major part of this skirt should be masked by the base  4  shown solely in dashed and dotted lines. 
     The skirt  6  is constituted by a front part  6 A detailed hereinafter and by a cylindrical rear part  6 B of axis X-X. The outer face of the rear part  6 B is provided, at its front end, with a projecting rib  6 B 1  which extends over the whole periphery of the skirt. This rib  6 B 1  thus defines with the rest of the outer face of the part  6 B, a shoulder  6 B 2 . 
     Unlike the rear part  6 B, the front part  6 A of the skirt  6  does not extend, in cross section, over the whole of the circular periphery of the base  4 , but is interrupted in the upper part, i.e. in the upper parts of  FIGS. 1 to 3 , with the result that a partition or rib  8  connects the interrupted opposite skirt parts. 
     The partition  8  comprises, on the one hand, an axial wall  8 A which projects towards the rear of the base  4  essentially in the direction X-X and which presents a substantially U-shaped cross section ( FIGS. 2 and 3 ) and, on the other hand, a radial wall  8 B parallel to the base  4 , from which the axial wall  8 A projects forwardly and which extends radially upwardly up to the rear part  6 B of the skirt  6 , forming the front end of the rib  6 B 1 . 
     The axial wall  8 A is constituted by a front part  8 A 1  and by a rear part  8 A 2  of which the depth, with respect to the level where the front part  6 A of the skirt  6  is interrupted by the partition  8 , is less than that of the front part  8 A 1 . A transverse part  8 A 3  connects the front ( 8 A 1 ) and rear ( 8 A 2 ) parts of the axial wall  8 A. 
     In this form of embodiment, the partition  8  and the skirt  6  form one piece, integral with the base  4 . In other words, the head  2  constituted by the base  4 , the skirt  6  and the partition  8  is a one-piece part, preferably made of a synthetic material. This part is, for example, obtained by molding. 
     A sleeve  10  of axis X-X is rigidly mounted, for example by force-fitting, around the rear part  6 B of the skirt  6 , being axially wedged against the shoulder  6 B 2  and with the possible interposition of an O-ring or the like (not shown). This sleeve internally receives a motor  12  and its associated reduction gear  14  from which extends an output shaft  16  in engagement with a distance piece or a transverse disc  18  of the winding tube T. On the structure S side, the tube T is supported by the front part  6 A of the skirt  6 , with the interposition of an annular ring  20  centered on the axis X-X and kinematically linked to the tube. 
     The ring  20  is provided with an inner toothing  20 A in mesh with a cylindrical double-tooth pinion  22  at its rear toothing  22 A. This pinion is mounted to rotate freely about a shaft  24  parallel to axis X-X and supported by the radial wall  8 B of the partition  8 . The front toothing  22 B which is of smaller diameter than that of the pinion rear toothing  22 A is in mesh with a toothed wheel  26  mounted to rotate freely about a shaft  28  supported by the base  4  of the head  2 . The diameter of the toothing  22 B is smaller than that of the toothing  22 A, such that the movement of rotation of the wheel  26  is geared down with respect to that of the ring  20 , i.e. that of the winding tube T. 
     In order to render the mechanical part constituted by the pinion  22  and the wheel  26  as compact as possible, the wall  8  is advantageously dimensioned both so that the depth of the rear part  8 A 2  of the axial wall  8 A is substantially equal to the outer diameter of the rear toothing  22 A of the pinion  22 , for the axial distance separating the base  4  from the transverse part  8 A 3  of the axial wall  8 A to be substantially equal to the axial dimension of the wheel  26 , this ensuring axial wedging of the latter, and so that the axial distance separating the base  4  from the radial wall  8 B is substantially equal to the sum of the axial dimensions of the wheel  26  and the pinion  22 , this ensuring the axial wedging of the pinion. By respecting the detailed dimensioning hereinabove, it is possible, by way of variant (not shown), to dispense with the shafts  24  and  26 , the partition  8  ensuring guiding of the pinion  22  and the wheel  26  in rotation. The spacings of the respective branches of the U&#39;s formed by the transverse sections of the front ( 8 A 1 ) and rear ( 8 A 2 ) parts of the wall  8 A, as well as the curvature of the bottom of these U&#39;s, then correspond to the respective diameters of the wheel  26  and of the toothing  22 A of the pinion  22  and to their respective curvature. 
     The wheel  26  is polarized, i.e. it is provided along its periphery with a succession of magnetic poles, in a predetermined geometry. This wheel is for example made of plastoferrite magnetized after injection. By noting the position and the displacement of these magnetized zones about shaft  28 , it is possible to determine the position and corresponding displacement of the tube T. 
     To that end, the device  1  comprises two Hall effect sensors  30  connected to an electronic processing unit  32 . More precisely, the device  1  is equipped with a printed circuit board  34 , connected to the head  2  and projecting from the base  4  in the direction X-X in part below the partition  8 . The board is for example slid and retained in appropriate notches  6 A 1  provided on the inner face of the skirt  6  as shown in  FIGS. 2 and 3 . On this board are mounted, on the one hand, sensors  30  which, when the board is connected to the head  2 , are disposed substantially in the median transverse plane of the magnet wheel  26  so as to react to the magnetic fields generated by the magnetized zones of the wheel, and, on the other hand, the electronic components of the unit  32 , the sensors  30  being connected to this unit for example by electrical conductors provided in the board  34 . 
     The processing unit  32  is adapted to analyze the signals emitted by the Hall effect sensors  30  so as to determine the position and the movement of the magnet wheel  26  and consequently those of the winding tube T, as well as to control, if necessary, the electrical supply of the motor  12 , via a control link  36 . 
     In order to ensure tightness of the electronic components of the device  1 , i.e. the sensors  30  and the unit  32 , these components are located on the side, turned towards the motor  12 , of the partition  8  while the wheel  26  and the pinion  22  are located on the other side. In this way, any infiltration of water or of humidity penetrating between the tube T and the ring  20  remains limited to the level of the pinion  22  and of the wheel  26 , without being able to pass through the tight partition  8  to attain the sensors  30  and/or the unit  32 . In order not to disturb the Hall effect sensors  30 , the matter constituting the partition  8  does not induce any noteworthy electromagnetic disturbance. 
     In other words, the partition  8  defines on either side of its axial ( 8 A) and radial ( 8 B) walls two distinct compartments, namely a first, upwardly open compartment  40  which essentially receives the pinion  22  and the wheel  26  and which is axially closed at the front by the base  4  and at the rear by the radial wall  8 B and, on the other hand, a second compartment  42  closed radially by the skirt  6 , which essentially receives the sensors  30 , the electronic unit  32  and the board  34  and which is closed at the front by the base  4  and open at the rear. 
     It will be noted that the term “compartment” generally covers any hollow housing which, in transverse section, is defined at least in part by a substantially concave wall. 
     Along a transverse section of the device  1 , for example the section of  FIGS. 2 and 3 , these compartments  40  and  42  are advantageously superposed, the axial wall  8 A of the partition  8  being interposed therebetween. In this way, the space requirement of the device  1  in length is reduced. Moreover, as the magnet wheel  26  is axially located between the base  4  and the pinion  22 , the axial space requirement of the compartment  40  is reduced and the sensors  30  located in the compartment  42  are brought as close as possible to the base  4  in order to detect the magnetic fields generated by the wheel so as to disengage a considerable free volume in the compartment  42  to arrange the board  34  and the electronic components of the unit  32 . Furthermore, by molding the base  4 , the skirt  6  and the partition in one piece, a part is obtained which determines both the position of the magnet wheel  26  and the position of the sensors  30 , this making it possible to master, as best possible, the tolerances determining the relative positioning of the wheel and the sensors. 
     The part  8 A 1  of the wall  8 A is concave seen from the housing  40  and convex seen from the housing  42 . In this way, the wheel  26  is partially surrounded by the partition  8 . In practice, the partition  8  surrounds the wheel  26  over about 180°. 
     The housing  40 , which is concave around the wheel  26 , is compact and extends only over a relatively small angular sector with respect to the periphery of the skirt  6 . 
     The geometry of the partition  8  makes it possible, particularly thanks to its portions  8 A 1  and  8 A 2 , to receive in the housing  40  the transmission formed by elements  22  and  26  which constitute a movement multiplier assembly allowing a detection of the rotation of the tube T with high precision, while this assembly is compact. 
     The use of a multiplier assembly  22 ,  26  which has a relatively large pole pitch, makes it possible to space the sensors  30  from the wheel  26  without risk of interference between the poles of the wheel  26 . In this way, the sensors  30  do not have to be in the immediately vicinity of the wheel  26 , this making it possible to design the wall  8  with a sufficient thickness to ensure good solidity of the assembly. 
     The geometry of the partition  8  also means that the sensors  30 , the board  34  and the unit  32  may be localized in a central part of the tube T. These elements  30 ,  32  and  34  therefore do not have to be especially configured to be disposed in the vicinity of the internal wall of the tube which is not planar. 
     The device  1  functions as follows: 
     When the screen E is wound around the tube T or unwound from that tube, the latter drives in rotation, in a corresponding movement, the annular ring  20  whose movement is transmitted to the magnet wheel  26  via the pinion  22 . The position and the displacement of this wheel, representative of the position and the displacement of the tube T, are detected by the sensors  30  of which the signals are transmitted to the processing unit  32  which then determines by calculation the position and the displacement of the tube. As a function of a pre-determined setting, the unit  32  then controls, if necessary, the stopping or slowing down of the motor  12 , for example if the unit concludes that the screen E has arrived at the end of stroke. 
     By using two Hall effect sensors  30  as in device  1 , it is possible to identify the direction of rotation of the magnet wheel  26 , and consequently that of the winding tube T. By way of variant, one sole Hall effect sensor  30  is provided, particularly if the determination of the direction of rotation is not necessary or if it is determined by other means. 
       FIGS. 5 and 6  show a variant of the drive device  1  of  FIGS. 1 to 3 . In this variant, the magnet wheel  26  is replaced by a disc-shaped optical wheel  50 , which bears over its periphery eight bevelled reflecting surfaces  52 . In order to allow detection of the position and the movement of this wheel  50 , the sensors  30  of the device of  FIGS. 1 to 3  are replaced by one or more assemblies constituted by an emitter  54  of light beams and a corresponding receiver  56  connected to a processing unit similar to unit  32 , able to process electronically the signals furnished by this receiver. This receiver is adapted to detect the reflection of the light beam emitted by the emitter  54  on one of the reflecting surfaces  52 . 
     In this variant, the tight partition  8  is interposed between the optical wheel  50  and the or each emitter  54 /receiver  56  assemblies, as shown in  FIG. 5 . 
     The partition  8 , or at least that part of the partition located on the path of the light beams, i.e. opposite the emitter  54  and the receiver  56 , is constituted by a material transparent to the light beams employed. The partition  8  is in that case made, for example, by means of a molding technique with two materials or by the addition of a transparent welded element. 
     Various arrangements and variants to the drive devices described hereinabove may in addition be envisaged. By way of example:
         the partition  8  is connected tightly on the base  4  of the head  2 , by screwing, clipping or adhesion for example.   the detection means, such as the Hall effect sensors  30 , may be embedded in the material constituting the partition  8 ; and/or   that part of the base  4  which closes the front of the compartment  40  may be axially pierced to allow the introduction of the pinion  22  and the wheel  26  in this compartment; in that case, the transverse section of the axial wall  8 A 1  may be more closed on itself, for example shaped as a C, while remaining open in a zone of its periphery to ensure meshing of the toothings  20 A and  22 A.

Summary:
A device including a tube for winding and unwinding a screen which is controlled in rotation by a gear motor and which is supported on a fixed head and wherein a rotational part mounted within the tube is kinematically linked to rotate with the tube with the part including elements that are used to reflect a position of the rotational part and which elements are detected by senors that are connected to an electronic processing unit. A tightly sealed partition secured to the head is further provided to define, on one side, a first compartment for receiving at least the rotational part and, on the other side, a second compartment for receiving at least the electronic processing unit.