Claims
- 1. A substrate of a disk for recording information, wherein
said substrate is made of glass containing SiO2 in an amount of 40-80% by weight, Al2O3 in an amount up to 17% by weight, and at least one rare earth element selected from the group consisting of Sc, Y, Pr, Nd, Pm, Sm and Eu, and has a transmittance for visible white light of said substrate is at least 60% and a surface roughness of 5 nm or less.
- 2. A substrate according to claim 1, wherein
said substrate comprises fine particles having an average particle size in the range of 1-100 nm and a glass matrix, and said find particles are dispersed in said glass matrix.
- 3. A substrate according to claim 2, wherein
said fine particles are crystalline and said glass matrix is amorphous.
- 4. A substrate according to claim 2, wherein
said glass matrix is any of soda lime glass and silicates glass.
- 5. A substrate according to claim 2, wherein
said rare earth element is included in said fine particles and said glass matrix.
- 6. A substrate according to claim 2, wherein
a volume fraction of said fine particles is in the range of 1%-40% to the total volume of said substrate.
- 7. A substrate according to claim 1, wherein
said substrate has a hardness at least Hv 640.
- 8. A substrate according to claim 1, wherein
said substrate has thermal expansion coefficient in the range of 70-130×10−7.
- 9. A substrate according to claim 1, wherein
said substrate includes said rare earth element in the range of 0.5-15% by weight to the total amount of said substrate on a basis of converted weight to oxide Ln203 (Ln is rare earth element).
- 10. A recording information disk comprising a layer for recording information and a substrate, wherein
said substrate is the substrate claimed in claim 1.
- 11. A recording information disk comprising a magnetic disk comprising the substrate according to claim 1 and a layer for recording information comprising a magnetic recording medium film.
- 12. A recording information disk according to claim 11, wherein
said magnetic recording medium film is formed directly on the surface of said substrate.
- 13. A recording information disk according to claim 10, wherein
said recording information disk is a photodisk or a photomagnetic disk, the thickness of said substrate is, at the utmost, 0.38 mm, and the diameter of said substrate is at least 2.5 inches.
- 14. An information recording disk apparatus comprising a disk for recording information,
a head for reading out information from said disk or inputting information to said disk, a driver for said disk, and a driver for said head, wherein said disk is the recording information disk claimed in claim 10.
- 15. An hard disk apparatus comprising a magnetic disk for recording information,
a head for reading out information from said magnetic disk or inputting information to said magnetic disk, a driver for said magnetic disk, and a driver for said head, wherein said magnetic disk comprises the substrate claimed in claim 1.
- 16. A photomagnetic disk for recording information, comprising the substrate according to claim 1.
- 17. A substrate of a disk for recording information, wherein
said substrate is made of glass containing SiO2 in an amount of 40-80% by weight, Al2O3 in an amount up to 17% by weight, and at least one rare earth element selected from the group consisting of Sc, Y, Pr, Nd, Pm, Sm and Eu, has a transmittance for visible white light of said substrate is at least 60% a surface roughness of 5 nm or less, and is made without a chemical strengthening treatment or crystallizing treatment.
Priority Claims (2)
Number |
Date |
Country |
Kind |
8-189058 |
Jul 1996 |
JP |
|
8-282068 |
Oct 1996 |
JP |
|
Parent Case Info
[0001] This is a continuation of application Ser. No. 08/888,124, filed Jul. 3, 1997.
Continuations (3)
|
Number |
Date |
Country |
Parent |
09641764 |
Aug 2000 |
US |
Child |
10767201 |
Jan 2004 |
US |
Parent |
09487785 |
Jan 2000 |
US |
Child |
09641764 |
Aug 2000 |
US |
Parent |
08888124 |
Jul 1997 |
US |
Child |
09487785 |
Jan 2000 |
US |