Optically readable information disc

Abstract

An optically readable information disc ( 150, 250, 350, 450, 550, 850 ) is disclosed as having an upper major surface ( 152 ), a lower major surface ( 156, 554, 854 ) and at least a peripheral edge ( 162 ) joining the major surfaces, further including engagement mechanism ( 164, 252, 352, 452, 456, 552 ) along at least part of the peripheral edge for engagement with a holder ( 100, 200, 300, 400, 500 ).

1 . An optically readable information disc having an upper major surface, a lower-major surface and at least a peripheral edge joining said major surfaces, characterized in that means is provided along at least part of said peripheral edge for engagement with a holder.  
     
     
         2 . A disc according to  claim 1  further characterized in that said upper major surface is smaller than said lower major surface.  
     
     
         3 . A disc according to  claim 1  further characterized in that said peripheral edge includes at least one stepped/chamfered portion.  
     
     
         4 . A disc according to  claim 3  characterized in that said stepped/chamfered portion is substantially straight.  
     
     
         5 . A disc according to  claim 3  characterized in that said stepped/chamfered portion is curved.  
     
     
         6 . A disc according to  claim 3  further characterized in that said peripheral edge includes a plurality of stepped/chamfered portions.  
     
     
         7 . A disc according to  claim 6  further characterized in that said peripheral edge includes two opposite stepped/chamfered portions, each at a longitudinal end of said disc.  
     
     
         8 . A disc according to  claim 6  further characterized in that said plurality of stepped/chamfered portions are provided at comers of said disc.  
     
     
         9 . A disc according to  claim 1  further including at least a recess on a stacking ring on said lower major surface.  
     
     
         10 . A disc according to  claim 9  further including a plurality of recesses on said stacking ring.  
     
     
         11 . A disc according to  claim 10  further characterized in that at least two diametrically opposite recesses are positioned on said stacking ring.  
     
     
         12 . A disc according to  claim 1  further including a pair of curved ridges on said lower major surface.  
     
     
         13 . A disc according to  claim 12  further characterized in that each of said ridges is of the shape of an arc of a circle of a diameter larger than the width of said disc.  
     
     
         14 . A disc according to  claim 12  further characterized in that at least a recess is provided along each of said curved ridges.  
     
     
         15 . A disc according to  claim 14  further characterized in that said recesses are diametrically opposite to each other.  
     
     
         16 . A disc according to  claim 14  further characterized in that a plurality of said recesses are provided along each of said curved ridges.