Ex Parte MIYAGAWA et al - Page 3




               Appeal No. 2006-0386                                                                                              
               Application 09/460,222                                                                                            

                      The figures of the original patent depict eight different embodiments of apparatus                         
               for recording data on or reproducing data from two different types of optical discs each                          
               having a recording layer and a substrate layer.  In the “first” type of disc, depicted in                         
               Figure 4A, the substrate has a thickness d1 of 1.2 mm.  Original Patent, col. 5, ll. 66-                          
               67.2   Nishiuchi et al. Patent 5,097,464 (“Nishiuchi”), which was applied during                                  
               prosecution of the original patent, explains that this is the commonly used substrate                             
               thickness for optical discs.  Nishiuchi, col. 1, ll. 25-28.  In the “second” type of disc,                        
               depicted in Figure 4B, the substrate has a smaller thickness d2 of, for example, 0.3 mm.                          
               Original Patent, col. 6, l. 6.  As explained at column 1, lines 21-65, the smaller                                
               thickness of this substrate is due to the fact that it is designed to record a higher density                     
               of information than is possible using the conventional, thicker substrate.  Specifically,                         
               higher-density recording requires a reduced spot diameter (D), which is related as                                
               follows to the laser wavelength (λ) and the numerical aperture (NA) of the focusing lens:                         
                                     D ∝ λ/NA                                                                                    
               Thus, the recording density can be increased by increasing the numerical aperture and                             
               thereby decreasing the spot diameter.  While increasing the numerical aperture will                               
               inherently cause an increase in coma aberration, that effect is avoided or reduced by                             
               reducing the thickness of the substrate.  Another problem is that an objective lens which                         
               is designed for use with the thinner, high-density optical disc will suffer from an                               
                                                                                                                                
                      2  All citations herein to the specification of the reissue application, which does                        
               not include line numbers, are to the specification of the original patent, which does.                            
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