Patent Publication Number: US-2009231417-A1

Title: Protective Glasses

Description:
TECHNICAL AREA 
     The invention concerns eye protective glasses for an operator working in the vicinity of one or more visible or invisible light radiation sources, e.g. of laser type. 
     STATE OF THE PRIOR ART 
     In the area of eye protection equipment against light radiation, suppliers of glasses offer solutions which are means for attenuating or passively reflecting this radiation, with no possible upgrading of these glasses in terms of the supply of ancillary services. 
     Also said solutions do not fully meet the needs of the invention:
         Prior art protective glasses are only supplied for fixed wavelength ranges.   These protective glasses do not allow laser beams, which emit in the non-visible range, to be seen. They therefore require the use of an alignment laser beam in a wavelength other than working laser beam wavelengths.   These protective glasses are calibrated for certain power values. If these are high, this prevents good visibility of the environment which is of lower intensity.   These protective glasses, by achieving protection by reflection, generate a risk for other operators and even for surrounding equipment.   These protective glasses, even if properly calibrated, may be damaged by the received beams or by mechanical scratching. They then become potentially dangerous since such damage is not always perceptible. Regular inspection of these glasses is therefore necessary.   For certain power levels no effective eye protection glasses exist.       

     The object of the invention is to propose an interface between the operator&#39;s eyes and a source of external radiation, providing full eye protection irrespective of the wavelength or power of the radiation. However it does not concern the protection of said operator&#39;s eyes against the effects of a very high powered laser, such as a cutting laser. 
     DESCRIPTION OF THE INVENTION 
     The invention concerns eye protection glasses for an operator in the vicinity of one or more light sources e.g. of laser type, comprising:
         digital viewing glasses,   at least one video camera,   a command device with a power source,
 
characterized in that they comprise two switchable video cameras:
   a first movement video camera, to view surroundings when the operator moves within the environment,   a second video camera for adjustment, used to view the work area.       

     The digital viewing glasses may be virtual viewing glasses with double LCD display. The video camera may be a camera of &lt;&lt;pin-hole&gt;&gt; type, either CCD or CMOS. 
     The protective glasses of the invention may be coated with an absorbent coating. 
     In a first variant of embodiment, the command device also comprises a video transmitting unit able to transmit a go signal towards a remote processing unit. 
     In a second variant of embodiment, the command device also comprises a video receiving unit able to receive a return signal from a remote processing unit and to send this processed video signal to the digital viewing glasses. 
     The first video camera for movement may be a CCD camera for example with a wide view angle, large field depth and functioning in the visible range. 
     The second video camera for adjustment may be a CCD camera for example with a viewing angle narrower than the first camera, a smaller field depth and functioning in the visible or non-visible ranges. 
     The protective glasses of the invention have numerous advantages compared with known protective glasses in the prior art:
         They do not function by attenuating light intensity and do not disturb perception of surroundings when moving within the environment, to look for equipment, take notes, read procedures or any other actions performed by the operator e.g. in a laser room.   They remain effective irrespective of the wavelength and power of the radiation source. This avoids errors in the choice of protection to be used in a given installation.   They allow an operator to work in a laboratory using several lasers of different wavelengths.   They allow the viewing of some pulsed lasers, by taking advantage of the acquisition time of the sensor used in the video camera.   For high flows, these glasses can be coated with an absorbent coating which eliminates any reflection-related problems.   Through proper choice of the camera technology, it is possible to view the environment of an intense light source allowing the operator to perceive a very bright spot on the screen, but nonetheless maintaining a perfect view of the remainder of the environment. Any eye glare is therefore fully cancelled out.   Said glasses have a low manufacturing cost and are lightweight.   They allow operators to work directly on lasers emitting in wavelengths invisible to the human eye, without having to use ancillary alignment lasers. The video camera is able to capture these wavelengths which can be reproduced on the viewing screens of the glasses in a visible colour, without fully disturbing the remainder of the viewed spectrum.   The adding of a hertz transmission system allows the movements and actions of an operator to be monitored remotely. This function opens up numerous possibilities in the area of safety or the preserving of knowledge for example.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  schematically illustrates one embodiment of the protective glasses of the invention. 
         FIGS. 2 ,  3  and  4  illustrate three variants of embodiment of the protective glasses of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS 
     As illustrated in  FIG. 1 , the protective glasses of the invention comprise:
         digital viewing glasses  10  arranged in front of the eyes  17  and  18  of an operator,   at least one video camera  11  directed towards the scene to be viewed (point  0 ), and which outputs a video signal SV towards these glasses  10 ,   a command device  12  comprising the power supply  19  for these glasses  10  and camera  11 , which can be worn on the operator&#39;s belt.       

     The glasses  10  and the video camera are both oriented towards one same point  0 . The angle a between the direction  27  perpendicular to the cell  20  of the camera, and the direction  28  perpendicular to the screens  13  and  14  of the glasses, illustrated in  FIG. 1 , can be adjusted in relation to the working distance. 
     In these glasses  10 , to simulate 3D viewing at working distance, the angle a must be a nonzero angle. 
     The digital viewing glasses  10  are virtual vision glasses originally dedicated to a games use (game console or portable DVD player). 
     These glasses  10  therefore comprise a screen ( 13 ,  14 ) associated with a lens ( 15 ,  16 ) in front of each eye ( 17 ,  18 ) of the operator, each screen receiving the signal SV. 
     Said glasses  10  allow immersion in a virtual scene. 
     The video camera  11  may be a CCD camera (&lt;&lt;Charge Coupled Device&gt;&gt;) comprising a CCD sensor  20  in the form of a matrix of pixels, each of these pixels producing electrons when it receives photons. Here the sensor  20  is associated with a lens  21 . The video camera  11  may also be a CMOS camera. 
     In a first variant of embodiment illustrated in  FIG. 2 , the command device  12 , in addition to the power supply  19 , comprises a video transmission unit  20  which transmits a go signal SVA, by hertz transmission or cable  21 , to a video receiving unit  23  and a viewing and recording unit  24  located in a remote processing unit  22 . 
     In a second variant of embodiment illustrated in  FIG. 3 , the remote processing unit  22 , in addition to the elements illustrated in  FIG. 2 , comprises a real-time digital image processing unit  30 , a video transmission unit  31  which transmits a return video signal SVR. The command device  12  comprises a video receiving unit  32  which receives this return signal SVR and whose output signal SV′ is sent to the digital viewing glasses  10 . 
     As illustrated in  FIG. 4 , the glasses of the invention use two video cameras which can be switched over:
         a first video camera for movement  40  (wide angle view, large field depth, sensor in the visible range),   a second video camera for adjustment  41  (narrower viewing angle, smaller field depth, sensor in the visible or invisible range).       

     The first camera  40  is used to view the surroundings when moving within the environment. The second camera  41  is used to view the work area. Each camera outputs a video signal (SV 1 , SV 2 ). In  FIG. 4 , the ellipse  43  illustrates the field of vision when moving within the environment. Ellipse  44  illustrates the working field of vision. In the glasses, the user is able to change over from one viewing mode to the other by means of a switch  42 . 
       FIG. 4  does not illustrate the fact that this switch  42  is used to command powering of the camera that is in use, and to cut out the other camera for the purpose of preserving the lifetime of the power supply  19 , consisting for example of rechargeable batteries. 
     Example of Embodiment 
     In one example of embodiment, the constituent parts of the glasses of the invention are as follows. 
     The digital viewing glasses  10  are digital glasses with two LCD screens (Liquid Crystal Display) with a resolution of 180 000 pixels, which are positioned in front of each of the operator&#39;s eyes, and therefore having a double LCD display e.g. of the type &lt;&lt;RIMAX Virtual Vision 2-0&gt;&gt;. 
     The video camera  11  is a CCD camera with a &lt;&lt;pin-hole&gt;&gt; lens, for example a camera of &lt;&lt;Snake CCD Camera&gt;&gt; type manufactured by MISUMI (MS-C493A-3C-P01). The positioning of this camera is calculated to obtain maximum precision at a distance corresponding to a reading distance (eye/book). This choice of the &lt;&lt;pin-hole&gt;&gt; characteristic is made to obtain maximum depth of field. 
     The glasses  10 +camera  11  assembly can be coated with an absorbent coating. 
     The powering  19  of these glasses  10  and of the video camera  11  is obtained using rechargeable batteries which can be worn on the operator&#39;s belt. The protective glasses of the invention are therefore fully self-powered. Said viewing assembly is neither more cumbersome, nor any heavier than some prior art protective glasses. 
     Said protective glasses can be used in particular as protective glasses by persons using lasers of a class higher than 2, by arc welders, by operators working in the vicinity of a furnace. 
     In general said protective glasses can be used for protection against any light radiation which may be detrimental to eye integrity, or in any areas in which possible glare carries a risk. 
     In addition, with said protective glasses it is possible to view invisible wavelengths.