Disc substrate, method and apparatus for manufacturing same

Abstract

A disc substrate of synthetic resin used for signal recording/reproduction by a head having a floating slider, in which the disc substrate is deburred to remove defects in appearance and is improved in strength and quality, and the manufacturing method and apparatus for the disc substrate. The manufacturing method includes a step of illuminating the laser light on at least the outer or inner rim portion of the disc substrate 2 of synthetic resin for transiently melting the illuminated portion. The manufacturing apparatus 1 includes a worktable 3 for supporting the disc substrate 2 in rotation, a positioning unit for positioning the disc substrate 2 at a pre-set position on the worktable 3 and a laser light source 4 for illuminating the laser light illuminating the laser light on the disc substrate 2 supported for rotation by the worktable 3 . On the outer rim of the disc substrate 2 is formed a raised portion 26 not larger than 15 μm in height. The raised portion 26 has a thickness larger than that of the outermost portion of the disc substrate 2.

What is claimed is:  
     
         1 . A method for manufacturing a disc substrate comprising the step of: 
 illuminating a laser light beam on at least the outer rim or the inner rim portions of a disc substrate of synthetic resin for at least transiently melting the illuminated portion said disc substrate being such a disc substrate used for signal recording/reproduction by a head having a floating slider.    
     
     
         2 . The manufacturing method as claimed in  claim 1  wherein the laser light beam is illuminated at an angle of 30° to 45° relative to the surface of said disc substrate.  
     
     
         3 . The manufacturing method as claimed in  claim 1  wherein the laser light beam is illuminated on the outer rim portion of the disc substrate for forming a raised portion 15 μm or less in height on the outer rim portion of the disc substrate.  
     
     
         4 . An apparatus for manufacturing a disc substrate comprising: 
 a worktable adapted for supporting a disc substrate and for being run in rotation;    a positioning member for positioning the disc substrate at a pre-set position on the worktable; and    a laser light source for being positioned by said positioning member and for subsequently illuminating the laser light on at least the outer or inner rim portions of the disc substrate supported for rotation by said worktable.    
     
     
         5 . The apparatus for manufacturing the disc substrate as claimed in  claim 4  wherein the positioning member is inserted in a center opening formed in the disc substrate for positioning the disc substrate.  
     
     
         6 . The apparatus for manufacturing the disc substrate as claimed in  claim 4  wherein the laser light source illuminates the laser light at an angle of 30° to 45° on the surface of the disc substrate.  
     
     
         7 . The apparatus for manufacturing the disc substrate as claimed in  claim 4  wherein the worktable has a disc suction opening for sucking and immobilizing the disc substrate.  
     
     
         8 . The apparatus for manufacturing the disc substrate as claimed in  claim 4  further comprising: 
 suction means for sucking a product formed on evaporation of the material of the disc substrate as a result of illumination of the laser light.  
 
     
     
         9 . The apparatus for manufacturing the disc substrate as claimed in  claim 4  wherein the laser light source illuminates the laser light on the outer rim portion of the disc substrate for forming a raised portion 15 μm or less in height on the outer rim portion of the disc substrate.  
     
     
         10 . A disc substrate of synthetic resin used for signal recording/reproduction by a head having a floating slider, wherein 
 the disc substrate has a raised portion at an outer rim portion, with the thickness of the disc substrate at the raised portion being thicker than the thickness of the outermost rim of the disc substrate, with the raised portion being 15 μm or less in height.