You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a maneuvering mechanism and to a closing or sun-protection installation comprising such a mechanism. 
   2. Brief Description of Related Art 
   Closure installation is understood to mean doors, portals, blinds, shutters and equivalent equipment. 
   In a closing or sun-protection installation, it is known to use a mechanical or electrical driving element for rotating, about its principal geometrical axis, a winding shaft for a closing screen of an opening, or for an effort transmission member such as a strap, associated with such a screen. 
   It is known to compensate the torque exerted on the winding mechanism by the weight of the closing screen, such compensation being obtained by one or more so-called “compensating” springs. Winding mechanisms comprising compensating springs are known, for example, from FR-A-2 743 107, from DE-A-296 05 670 or from JP-A-2000-234485. In these devices, there are provided, on the one hand, a tubular drive motor and, on the other hand, compensating springs, these springs and this motor having to be placed in position in the winding shaft on the site of use of the installation, while the working conditions of the installer are sometimes precarious, particularly due to a limited accessibility in height. In addition, numerous parts must be provided in order to install, on the one hand, the compensating spring and, on the other hand, the motor inside the winding shaft, this rendering the known installations more expensive. 
   It is a more particular object of the invention to overcome these drawbacks by proposing a maneuvering mechanism which comprises at least one compensating spring and which may be easily placed in position, while its cost price is more attractive than that of the known compensated mechanisms. 
   SUMMARY OF THE INVENTION 
   In this spirit, the invention relates to a mechanism for maneuvering a closing or sun-protection installation comprising an element for driving in rotation a winding shaft for a closing screen and at least one spring for compensating the weight of this closing screen. This mechanism is characterized in that the spring is mounted around the driving element and belongs with the latter to a sub-unit adapted to be at least partially introduced in unitary manner inside the winding shaft, a first end of the spring being kinematically linked to the driving element, while its second end is adapted to be kinematically linked to this shaft when the sub-unit is in place in the shaft. 
   Thanks to the invention, the driving element, which may be an electric motor, and the compensating spring may be manipulated and placed in position in a relatively simple operation, this facilitating the work of the installer, reducing the assembly time and reducing the number of accessory parts necessary. 
   According to advantageous but non-obligatory aspects of the invention, this mechanism incorporates one or more of the following characteristics:
         The second end of the spring is fast with a driving element adapted to be connected with the shaft, inside the latter.   The second end of the spring is fast with a ring mounted to rotate freely about a casing of the driving element. This ring is advantageously fast in rotation with an output shaft of the driving element. In a variant, it may be rendered directly fast in rotation with the winding shaft, with the result that the output shaft of the driving element is not urged by the compensating spring. This makes it possible to avoid the reduction gear conventionally provided at the output of an electric motor being subjected during a relatively long storage period to an effort exerted on the output shaft by the loaded spring in a configuration of compensation of the maximum torque exerted by the closing screen. In particular, the ring may be provided to present at least one element in relief adapted to come into mesh with a corresponding element in relief provided on the winding shaft for connection of this ring and this shaft in rotation.   The first end of the spring is anchored on a casing of the driving element.   The first end of the spring is fast in rotation with a ring immobilized around a casing of the driving element.   The spring has such a length that it does not project substantially, in an axial direction, with respect to a casing of the driving element.   The driving element may comprise an electric motor, possibly associated with a reduction gear.       

   The invention also relates to an installation for closure or sun protection which comprises a maneuvering mechanism as described previously. Such an installation is easier to position and more economical than those of the state of the art. 
   The invention will be more readily understood and other advantages thereof will appear more clearly in the light of the following description of three forms of embodiment of a closure installation equipped with a maneuvering mechanism according to the invention, given solely by way of example and made with reference to the accompanying drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  schematically shows a partial axial section of a part of a closure installation in the course of assembly. 
       FIG. 2  is a partial axial section of the installation of  FIG. 1  in configuration of use. 
       FIG. 3  is a section similar to  FIG. 1 , for an installation in accordance with a second form of embodiment of the invention. 
       FIG. 4  is a section similar to  FIG. 2  for the installation of  FIG. 3 . 
       FIG. 5  is a section similar to  FIG. 1 , for an installation in accordance with a third form of embodiment of the invention, and 
       FIG. 6  is a section similar to  FIG. 2  for the installation of  FIG. 5 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The installation shown partially in  FIGS. 1 and 2  comprises a mechanism  1  making it possible to wind a screen body T more or less around a geometrical axis X-X′, this making it possible to close more or less an opening O made in the masonry of a building. 
   The mechanism  1  comprises a shaft  2  whose central geometrical axis merges with axis X-X′ and which is supported with respect to the structure of the building by means of a bracket  3  forming bearing. 
   A driving element  4  is provided to rotate the shaft about axis X-X′, as represented by arrow R in  FIG. 2 . This element comprises an electric motor  41  and a reduction gear  42 .  43  denotes the output shaft of the element  4 , and  44  its casing inside which elements  41  and  42  are housed. 
   A compensating spring  5  is provided in order to compensate the torque exerted by the weight of the screen body T about the axis X-X′. This spring is a torsion spring disposed helically around the casing  44  of the element  4 . 
   The casing  44  is provided with a catch  45  around which is anchored a first end  51  of the spring  5  which is shaped as a loop. 
   The second end  52  of the spring  5  is introduced in a housing  62  made in a drive disc  6  provided to be connected in rotation with the shaft  2  by any appropriate means, for example by riveting. 
   The disc  6  is provided with a central opening  61  whose section is adapted to the section of the shaft  43 , with the result that the disc  6  is fast in rotation with the shaft  43 . 
   A spacer ring  7  is provided in order to centre the casing  44  in the shaft  2 , with possibility of rotation. 
   As is more particularly visible in  FIG. 1 , elements  3  to  7  constitute a sub-unit  10  which may be partially introduced, in one operation, inside the shaft  2 , as represented by arrow F 1 . In particular, the element  4  and the spring  5  belong to the unit  10  and are positioned in the shaft  2 . 
   L 5  denotes the length of the spring  5  taken in the direction of axis X-X′. L 4  denotes the length of the element  4  taken in the same direction. The length L 5  is less than length L 4  and the spring  5  substantially does not project beyond the casing  44 , this giving the sub-unit  7  a compact and monolithic character, simplifying its manipulation and allowing time to be saved when installing. 
   When the device is in operational configuration shown in  FIG. 2 , a rotation R of the shaft  2  induces a corresponding rotation of the disc  6  and a modification of the tension of the spring  5 , since its end  52  rotates about axis X-X′, while its end  51  remains fixed with respect to the casing  44  which is itself fixed with respect to axis X-X′. 
   In the second embodiment of the invention shown in  FIGS. 3 and 4 , elements similar to those of the first embodiment bear identical references increased by  100 . The mechanism  101  of this embodiment is likewise centred on an axis X-X′ and comprises a shaft  102  for winding a screen body T, this shaft being supported thanks to a bracket  103  and receiving a driving element  104  comprising an electric motor  141  and a reduction gear  142 . As previously, a spring  105  is mounted around the casing  144  of the element  104 , this spring being fast by its first end  151  with a catch  145  provided on the casing  144 . 
   A spacer ring  107  is disposed around the casing  144 , in the vicinity of the bracket  103 , with possibility of rotation, and allows a relative centering of the elements  102  and  104 . 
   A ring  108  is mounted to rotate freely about the end  144   a  of the casing  144  opposite the bracket  103 , this ring  108  being provided with a central opening  181  whose section is such that it may be driven in rotation by the output shaft  143  of the element  104 . The second end  152  of the spring  105  is fixed by any appropriate means on the ring  108 , for example by cooperation of shapes, clipping, gluing or welding. 
   A drive disc  106  is fixed inside the tube  102  when it is manufactured and is provided with an opening  161  for receiving the shaft  143 , the section of the opening  161  allowing a drive in rotation of the disc  106  from the shaft  143 . 
   The elements  103  to  107  and  108  constitute a sub-unit  110  which may be partially introduced in one operation inside the tube  102 , as represented by arrow F 1  in  FIG. 3 . 
   The length L 105  of the spring  105  parallel to axis X-X′ is less than the length L 104  of the element  104  parallel to this axis. 
   In the third form of embodiment of the invention shown in  FIGS. 5 and 6 , elements similar to those of the first embodiment bear identical references increased by  200 . The mechanism  201  of this embodiment comprises a shaft  202  for driving a screen body T for more or less closing an opening O. This shaft  202  is supported by a bracket  203  immobilized with respect to the masonry of the building. A driving element  204  comprises an electric motor  241  and a reduction gear  242  disposed inside a casing  244  of cylindrical shape with circular section, like casings  44  and  144 . 
     243  denotes the output shaft of the member  204 . This shaft  243  is provided to be introduced in an opening  261  of a drive disc  206  mounted fixed inside the shaft  202 . 
   A spring  205  is mounted around the casing  244  and immobilized in rotation thereon by clamping its first end  251  on a truncated ring  209 , itself immobilized on the end  244   a  of the casing  244  opposite the bracket  203 . 
   Another ring  208  is mounted around the casing  244 , at the level of its end  244   b  nearest the bracket  203 , the ring  208  being able to rotate about the end  244   b.    
   The ring  208  is, furthermore, provided with a truncated surface  282  for receiving and wedging the second end  252  of the spring  205 . 
   The ring  208  is also provided with a plurality of radial projections  283  intended each to be engaged in a notch  223  made at the level of the end  221  of the tube  202 . 
   The elements  203  to  205 ,  208  and  209  constitute a sub-unit  210  that may be introduced in one operation, represented by arrow F 1  in  FIG. 5 , inside the tube  202 , this sub-unit making it possible to perform the functions of drive of the tube  202  and of compensation, like the sub-units  10  and  110  of the first and second embodiments. 
   Due to the introduction of the sub-unit  210  in the tube  202 , the shaft  243  comes into engagement inside the opening  261 , while the projections  283  come into engagement in the notches  223 . 
   As shown in  FIG. 5 , when the installation is being placed in position, the ring  206  is mounted on the shaft  243  before the sub-unit  210  is introduced in the tube  202 , this avoiding a later adjustment of the relative orientation of the rings  206  and  208 . The same modus operandi may be employed with the mechanisms of the first and second embodiments. 
   This form of embodiment presents the particular advantage that, in the configuration of  FIG. 5  of the sub-unit  210 , which corresponds to its configuration of storage before being placed in position in an installation provided on a building, the torque exerted by the spring  205  between the rings  208  and  209  is not transmitted to the shaft  243 . In effect, there is provided a means for immobilizing the ring  208  in rotation with respect to the casing  244 , this means being able to be a key  211  as shown in dashed and dotted lines in  FIG. 5 . Any other immobilization means may, however, be envisaged, for example a fixation by screwing. 
   The position of the ring  208  may be adjusted, before its immobilization with respect to the casing  244 , so that the effort of compensation exerted by the spring  205  corresponds substantially to the effort of compensation to be exerted in order to compensate the maximum weight of the screen body T, i.e. its weight in closed configuration of the opening O. This maximum torque not being transmitted to the shaft  243  and consequently to the reduction gear  242 , this reduction gear may be dimensioned, taking into account the fact that, when the sub-unit  210  is in place in the shaft  202 , the weight of the screen body T and the effort of the spring  205  are compensated approximately. The reduction gear  242  may therefore be smaller and lighter than the reduction gears of the known installations, this enabling substantially savings to be made on the cost price of the mechanism  201 . 
   The length L 205  of the spring  205  is substantially shorter than the total length of the element  204 . 
   According to a variant of the invention (not shown), a mechanism in accordance with its principle may also be equipped with a safety device as described in French Patent Application No. 02 03942, corresponding to U.S. patent publication No. 2005/0109473 of which the contents are incorporated herein by reference. 
   The technical characteristics of the different forms of embodiment mentioned may be combined together without departing from the scope of the present invention. Similarly, obvious modifications may be made to the embodiments described without departing from the scope of the present invention.

Summary:
A mechanism ( 1 ) comprising a driving element ( 4 ) for rotationally driving a winding shaft ( 2 ) for a closing or sun-protection installation of an opening ( 0 ) and at least one spring ( 5 ) for compensating a weight of the installation. The spring ( 5 ) is mounted around the driving element ( 4 ) and is jointly associated with a sub-unit ( 10 ), which can be at least partially introduced in a unitary manner inside the shaft ( 2 ). The spring ( 5 ) includes a first end ( 51 ) kinematically linked to said driving element ( 4 ) so that the first end ( 51 ) is immobilized in rotation abut an axis of rotation (X-X′) of the shaft ( 2 ), and a second end ( 52 ) kinematically linked to the shaft ( 2 ) when the sub-unit ( 10 ) is placed inside the shaft ( 2 ) so that the second end ( 52 ) rotates about the axis of rotation (X-X′).