Abstract:
This optical assembly comprises a securing support ( 40 ), an optical focusing element ( 44 ) and a reflecting mirror ( 42 ) which is suitable for reflecting an incident light beam (F 1 ) towards the optical focusing element ( 44 ) in order to focus it onto an illumination plane (P). The reflecting mirror ( 42 ) is movable relative to the securing support ( 40 ). The optical focusing element ( 44 ) is movable relative to the securing support ( 40 ). The assembly includes elements for connecting the focusing element ( 44 ) to the mirror ( 42 ) for synchronised displacement of the two of them. The assembly is useful in devices for illuminating operating fields.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to an optical assembly of the type comprising: 
        a support for securing the assembly,     an optical focusing element and     a reflecting mirror which is suitable for reflecting an incident light beam towards the optical focusing element in order to focus it onto an illumination plane, the reflecting mirror being movable relative to the securing support.        
 
         [0005]     The invention applies in particular to devices for illuminating operating fields in the medical sector.  
       BACKGROUND TO THE INVENTION  
       [0006]     Document FR-A-2 793 676 describes an illumination device which comprises a casing, in which a bulb and optical assemblies are arranged. Each optical assembly comprises a mirror and an aperture. The mirror is suitable for reflecting a light beam emitted by the bulb towards the aperture which is suitable for focusing the beam onto an illumination plane.  
         [0007]     This device does not allow the size of the illumination spot to be varied for a given distance between the casing and the illumination plane.  
         [0008]     There are further known illumination devices which allow the extent of the illumination spot to be varied by the mirror being tilted relative to the casing. However, these devices comprise a casing whose zones surrounding the apertures are opaque in order to ensure homogeneous illumination. These opaque zones lead to poor light output and an unattractive casing.  
         [0009]     The object of the present invention is to overcome the disadvantages mentioned and to provide an assembly which allows the size of the illumination spot to be modified whilst still having good output.  
       SUMMARY OF THE INVENTION  
       [0010]     To this end, the invention relates to an assembly of the above-mentioned type, characterised in that the optical focusing element is movable relative to the securing support, and in that it comprises means for connecting the optical focusing element to the reflecting mirror for synchronised displacement of the two of them.  
         [0011]     According to specific embodiments, the invention comprises one or more of the following features: 
        the connection means fixedly join the reflecting mirror to the optical focusing element for identical movement of the two of them;     the reflecting mirror defines an optical mirror plane and the optical focusing element defines an optical focusing plane, the two optical planes intersect along an axis of intersection, and the reflecting mirror and the optical focusing element are movable in rotation about an axis of rotation which is parallel with the axis of intersection;     the assembly comprises means for adjusting the relative position of the reflecting mirror and the optical focusing element relative to the axis of rotation in a radial direction relative to this axis;     the optical focusing element is a through-aperture comprising a first dioptre lens and a second dioptre lens, in that the first dioptre lens is suitable for correcting optical aberrations and the second dioptre lens is suitable for making uniform the illumination over the illumination plane; and     the reflecting mirror and the optical focusing element are mutually connected by two connection plates which extend at one side and the other of the reflecting mirror and the optical focusing element.        
 
         [0017]     The invention further relates to an illumination device, in particular for illuminating an operating field, of the type comprising: 
        a casing comprising at least one means for securing a light source and     at least one optical assembly which is suitable for reflecting a light beam which is emitted by the light source towards the illumination field, characterised in that the optical assembly is a so-called movable assembly, as defined above, the securing support being fixed to the casing.        
 
         [0020]     According to specific embodiments, the device comprises one or more of the following features: 
        the device comprises at least two optical assemblies, of which half are movable assemblies and the other half are fixed assemblies, and each of the movable assemblies is an assembly as defined above;     half of the optical assemblies which are associated with a bulb are constituted by movable assemblies, whilst the other half of the optical assemblies are fixed assemblies.       
 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0023]     The invention will be better understood from a reading of the description below, given purely by way of example and with reference to the appended drawings, in which:  
         [0024]      FIG. 1  is a top view of an illumination device according to the invention, the casing being removed;  
         [0025]      FIG. 2  is a sectioned view along plane A-A of  FIG. 1 ; and  
         [0026]      FIG. 3  is an enlarged perspective view of a movable optical assembly of the device of  FIGS. 1 and 2 . 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0027]      FIG. 1  illustrates an illumination device according to the invention which is generally designated  2 . This device  2  is intended to illuminate an illumination field  4 , such as a medical operating field defined by an illumination plane P. To this end, the device  2  is suitable for creating an illumination spot  6  in plane P.  
         [0028]     The device  2  is provided with a casing  10  which comprises a housing  12  and a closure plate  14 . The housing  12  delimits an opening  16  which is directed towards plane P. The closure plate  14  closes the opening  16  and is completely transparent. It is produced in a single piece, for example, of plastics material. The casing  10  comprises four lobes  18  and has, when viewed from above, a generally symmetrical cross-like form.  
         [0029]     Two illumination assemblies  20  and  22  are arranged in the casing  10 .  
         [0030]     Each of the illumination assemblies  20 ,  22  comprises an illumination bulb  24 ,  26  which is retained in a bulb securing means  28 ,  30  and four condenser lenses  32 ,  34  which are known per se and which are arranged in the central portion of the casing. The condenser lenses  32 ,  34  are suitable for generating four light beams F 1  and F 2  which are directed from the associated bulb towards the lobes  18  and which define centre axes C-C.  
         [0031]     Each of the assemblies  20 ,  22  further comprises two movable optical assemblies  36  and two fixed optical assemblies  38 . Each of these assemblies is arranged in one of the lobes  18  and is suitable for reflecting one of the beams F 1 , F 2  towards the illumination plane P.  
         [0032]     A movable optical assembly  36  is illustrated in  FIG. 3 . This assembly  36  comprises a securing support  40 , a reflecting mirror  42  and a focusing aperture  44 .  
         [0033]     The securing support  40  is a fitting which is in the form of an inverted U and which is fixed to the housing  12  and constituted by a web  46  which connects two arms  48 ,  50 . Each arm  48 ,  50  is provided with a stud  52 ,  54  which is movable in rotation about an axis X-X.  
         [0034]     The reflecting mirror  42  is a planar mirror which extends in a mirror plane M. The mirror  42  is reflective in the range of visible light and transparent in the infrared range. An optical processed layer  56  which is known per se is arranged on the mirror, at the side opposite the aperture ( FIG. 1 ). This optical processed layer  56  serves to transmit the infrared rays towards the casing  12  in order to dissipate the energy of the infrared rays.  
         [0035]     The focusing aperture  44  extends in an aperture plane H which defines an angle of between 40° and 50° with the plane M. The two planes H and M intersect along an axis of intersection Y-Y. The aperture  44  comprises a first dioptre lens and a second dioptre lens which are arranged coaxially one behind the other in the sense of travel of the rays of the beams F 1 . The first dioptre lens is suitable for correcting optical aberrations and the second dioptre lens is suitable for making uniform the illumination of the beam F 1 .  
         [0036]     The mirror  42  and the aperture  44  are fixed to each other by two connection plates  58 ,  60  of generally triangular form which extend perpendicularly to the planes M and H. Each of the plates  58 ,  60  extends at an axial end of the mirror  42  and the aperture  44 . The connection plates  58 ,  60 , the mirror  42  and the aperture  44  therefore form a prism of triangular cross-section whose side located facing the mirror  42  and the aperture  44  is open.  
         [0037]     The radial position of the mirror  42  and the aperture  44  can be adjusted relative to axis X-X. For this purpose, a rectilinear slot  62  is provided in each plate  58 ,  60 . The associated stud  52 ,  54  extends through the slot  62  and is held in the slot by holding means, such as a nut  64 .  
         [0038]     In this manner, the plates  58 ,  60 , the mirror  42  and the aperture  44  are articulated to the arms  48 ,  50  of the fitting about the axis of rotation X-X by means of the studs  52 ,  54 .  
         [0039]     The axis X-X extends in parallel with the planes H and M and is offset from these planes. Furthermore, the axis X-X intersects with the centre axis C-C of the associated beam F 1 , F 2 .  
         [0040]     The assembly  36  further comprises a strut  66  which is fixed to the plate  60 . The strut  66  comprises an opening  68 , in which a drive finger is engaged which is not illustrated and which is connected to means for driving the strut  66 , such as a geared motor (not illustrated). In this manner, the mirror  42  and the aperture  44  can be displaced angularly in a synchronous manner and in a single unit about axis X-X in order to modify the size of the illumination spot  6 .  
         [0041]     Each fixed optical assembly  38  comprises a reflecting mirror  42  and a focusing aperture which are similar to the mirror  42  and aperture  44  mentioned above. However, the mirror  42  and aperture  44  in this case are secured to the housing  12  and the positions thereof cannot be modified relative to the casing  10 .  
         [0042]     The illumination device according to the invention is assembled and operates as follows.  
         [0043]     Firstly, the support  40  is secured in the casing  10 . Subsequently, the position of the mirror  42  and the aperture  44  relative to the bulb  24  is pre-adjusted by the position of the plates  58 ,  60  being modified relative to the studs  52 ,  54 .  
         [0044]     When the operating field  4  is illuminated, the size of the illumination spot  6  can be adjusted by the mirrors  42  and the apertures  44  of the movable assemblies  36  being tilted about the axis X-X.  
         [0045]     The provision of movable assemblies  36  and fixed assemblies  38  in the same casing  10  results in an illumination device which allows the size of the illumination spot  6  to be varied, whilst still being economical.  
         [0046]     The fixed illumination assemblies  38  further ensure minimum illumination at the centre of the spot  6 .  
         [0047]     In general terms, it is preferable for half of the optical assemblies to be constituted by fixed assemblies  38  whilst the other half are constituted by movable assemblies  36 . Similarly, it is preferable for half of the optical assemblies which are associated with a bulb to be constituted by movable assemblies  36  whilst the other half of the optical assemblies are constituted by fixed assemblies  38 .  
         [0048]     Since the mirror  42  and the aperture  44  of the movable assemblies  36  are fixed relative to each other, a modification of the position of the mirror  42  relative to the bulb  24  does not modify the position of the mirror  42  relative to the aperture  44 . Consequently, the aberration of the light beam F 1  which leaves the aperture  44  is still corrected in the same manner and it is not necessary partially to obscure this beam F 1 . This leads to good energy output of the device. Furthermore, the closure plate  14  can therefore be completely transparent and attractive.  
         [0049]     By way of a variant, all the movable optical assemblies  36  are associated with one of the bulbs  24 ,  26  whilst all the fixed optical assemblies  38  are associated with the other bulb  26 ,  24 .