Optical information medium, and method and apparatus for fabricating the same

Abstract

The disk-shaped optical information medium of this invention includes: a first substrate having a center hole; a second substrate having a center hole; and a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates, wherein the optical information medium further includes a stopper for preventing the radiation curable resin from protruding into the center holes of the substrates, and a space between the first and second substrates of at least half of a clamp region for clamping the optical information medium is filled with the resin.

1. An apparatus for fabricating an optical information medium by bonding together a first substrate having a center hole and a second substrate having a center hole with a radiation curable resin interposed therebetween, comprising:
 a table for integrally rotating the first and second substrates, with the radiation curable resin interposed therebetween, before the radiation curable resin is cured; and    centrally disposed means for absorbing through the center holes of the first and second substrates the radiation curable resin interposed between the first and second substrates.    
     
     
       2. An apparatus according to  claim 1 , wherein an outer diameter of the table is less than an outer diameter of each of the first and second substrates. 
     
     
       3. An apparatus according to  claim 2 , wherein the outer diameter of the table is about 70% or more than the outer diameter of each of the first and second substrates. 
     
     
       4. An apparatus according to  claim 1 , wherein the means for absorbing the radiation curable resin is at least one suction port. 
     
     
       5. An apparatus according to  claim 1 , wherein the means for absorbing the radiation curable resin is a plurality of suction ports. 
     
     
       6. An apparatus according to  claim 1 , wherein the means for absorbing the radiation curable resin comprises a suction pump. 
     
     
       7. An apparatus according to  claim 1 , wherein the means for absorbing the radiation curable resin comprises at least one suction port in a boss. 
     
     
       8. An apparatus according to  claim 1 , wherein the means for absorbing the radiation curable resin is a sponge. 
     
     
       9. An apparatus according to  claim 1 , wherein the resin which is absorbed is excess resin. 
     
     
       10. A disk- shaped optical information medium comprising:      a first substrate having a center hole;        a second substrate having a center hole;        a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates,        wherein the optical information medium further comprises a stopper for preventing the radiation curable resin formed at a portion closer to an outer circumference of the optical information medium with respect to the stopper from spreading toward a portion closer to an inner circumference of the optical information medium, and        the stopper is formed at a position closer to the center holes of the substrates with respect to the center of a clamp region for clamping the optical information medium, and a space between the first and second substrates of at least a half of the clamp region is filled with the radiation curable resin by spreading the radiation curable resin to the position of the stopper.     
     
     
       11. A disk- shaped optical information medium comprising:      a first substrate having a center hole;        a second substrate having a center hole; and        a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates,        wherein the optical information medium further comprises a ring - shaped groove substantially concentric with the center holes of the substrates, formed on at least one of the first and second substrates, and the ring - shaped groove prevents the radiation curable resin formed at a portion closer to an outer circumference of the optical information medium with respect to the ring - shaped groove from spreading toward a portion closer to an inner circumference of the optical information medium with respect to the ring - shaped groove, and        the ring - shaped groove is formed at a position closer to the center holes with respect to the center of a clamp region for clamping the optical information medium, and a space between the first and second substrates of at least a half of the clamp region is filled with the radiation curable resin by spreading the radiation curable resin to the position of the ring - shaped groove.     
     
     
       12. A method for fabricating an optical information medium, comprising the steps of:
   placing one of a first substrate having a center hole and a second substrate having a center hole on the other substrate with a radiation curable resin interposed therebetween;        curing the radiation curable resin by irradiating the radiation curable resin with radioactive rays capable of passing through at least one of the first and second substrates so as to bond the first and second substrates together; and        forming a stopper for preventing the radiation curable resin formed at a portion closer to an outer circumference of the optical information medium with respect to the stopper from spreading toward a portion closer to an inner circumference of the optical information medium, at a position closer to the center holes of the substrates with respect to the center of a clamp region for clamping the optical information medium,        wherein the step of placing one of the first and second substrates on the other substrate includes the step of filling a space between the first and second substrates of at least a half of the clamp region with the radiation curable resin by spreading the radiation curable resin to the position of the stopper.     
     
     
       13. A method for fabricating an optical information medium, comprising the steps of:
   placing one of a first substrate having a center hole and a second substrate having a center hole on the other substrate with a radiation curable resin interposed therebetween;        curing the radiation curable resin by irradiating the radiation curable resin with radioactive rays capable of passing through at least one of the first and second substrates so as to bond the first and second substrates together; and        forming a ring - shaped groove substantially concentric with the center holes of the substrates on at least one of the first and second substrates, wherein the ring - shaped groove prevents the radiation curable resin formed at a portion closer to an outer circumference of the optical information medium with respect to the ring - shaped groove from spreading toward a portion closer to an inner circumference of the optical information medium with respect to the ring - shaped groove, and the ring - shaped groove is formed at a position closer to the center holes with respect to the center of a clamp region for clamping the optical information medium,        wherein the step of placing one of the first and second substrates on the other substrate includes the step of filling a space between the first and second substrates of at least a half of the clamp region with the radiation curable resin by spreading the radiation curable resin to the position of the ring - shaped groove.     
     
     
       14. A disk- shaped optical information medium comprising:      a first substrate having a center hole and a thickness of  0 . 6  mm;        a second substrate having a center hole and a thickness of  0 . 6  mm; and        a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates,        wherein the optical information medium further comprises a stopper for preventing the radiation curable resin from protruding into the center holes of the substrates, and        a space between the first and second substrates of at least a half of a clamp region for clamping the optical information medium is filled with the resin.     
     
     
       15. A disk- shaped optical information medium comprising:      a first substrate having a center hole and a thickness of  0 . 6  mm;        a second substrate having a center hole and a thickness of  0 . 6  mm; and        a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates,        wherein the optical information medium further comprises a ring - shaped groove substantially concentric with the center holes of the substrates, formed on at least one of the first and second substrates at a position closer to the center holes with respect to the center of a clamp region for clamping the optical information medium, and        a space between the first and second substrates of at least a half of a clamp region is filled with the radiation curable resin.     
     
     
       16. A method for fabricating an optical information medium, comprising the steps of:
   forming a pair of substrates each having a center hole and a thickness of  0 . 6  mm;        placing one of the pair of substrates on the other substrate with a radiation curable resin interposed therebetween; and        curing the radiation curable resin by irradiating the resin with radioactive rays capable of passing through at least one of the pair of substrates so as to bond the pair of substrates together,        wherein the step of forming a pair of substrates includes the step of forming a stopper for preventing the radiation curable from protruding into the center holes on at least one of the pair of substrates, and        the step of placing one of the pair of substrates on the other substrate includes the step of filling at least a half of a clamp region of the optical information medium with the radiation curable resin.     
     
     
       17. An apparatus for fabricating an optical information medium by bonding together a first substrate having a center hole and a second substrate having a center hole with a radiation curable resin interposed therebetween, comprising:
   a table for integrally rotating the first and second substrates, with the radiation curable resin interposed therebetween, before the radiation curable resin is cured; and        centrally disposed means for absorbing through the center holes of the first and second substrates the radiation curable resin interposed between the first and second substrates.     
     
     
       18. An apparatus according to  claim 17 , wherein an outer diameter of the table is less than an outer diameter of each of the first and second substrates. 
     
     
       19. An apparatus according to  claim 18 , wherein the outer diameter of the table is about 70%  or more than the outer diameter of each of the first and second substrates.   
     
     
       20. An apparatus according to  claim 17 , wherein the means for absorbing the radiation curable resin is at least one suction port. 
     
     
       21. An apparatus according to  claim 17 , wherein the means for absorbing the radiation curable resin is a plurality of suction ports. 
     
     
       22. An apparatus according to  claim 17 , wherein the means for absorbing the radiation curable resin comprises a suction pump. 
     
     
       23. An apparatus according to  claim 17 , wherein the means for absorbing the radiation curable resin comprises at least one suction port in a boss. 
     
     
       24. An apparatus according to  claim 17 , wherein the means for absorbing the radiation curable resin is a sponge. 
     
     
       25. An apparatus according to  claim 17 , wherein the resin which is absorbed is excess resin.