Claims
- 1. A disc cartridge comprising:
a magnetic end unit; a cartridge body within which there is rotatably accommodated a first magnetic disc and a second magnetic disc, the first magnetic disc comprising a plurality of flat recording tracks provided on at least one surface of a first disc substrate formed by molding a synthetic resin and a magnetic layer covering the plurality of recording tracks, the second magnetic disc comprising a second disc substrate is formed by molding synthetic resin and information uneven pit trains where information is recorded and control uneven pit trains where control signals for controlling positions of the magnetic head unit are recorded on at least one surface, and a magnetic layer including a plurality of bottom surfaces and upper surfaces of the information uneven pit trains and the contol uneven pit trains, the magnetic layer being magnetized in a magnetization direction so that the magnetic layer portions on the plurality of bottom surfaces and that of the magnetic layer portions of the plurality of upper surfaces of the information uneven pit trains are different from each other so that information is recorded, the magnetic layer being further magnetized in a magnetization direction in which the magnetic layer portions on the plurality of bottom and that of the magnetic layer portions of the plurality of upper surfaces of the control uneven pit trains are different from each other so that control signals are recorded, and the first and the second magnetic discs being configured so that the magnetic head unit records and/or reproduces signals on the first or second magnetic disc, the magnetic head unit comprising a magnetic head element provided at a slider which rotation of the magnetic disc causes a floating force by air; an opening at one side surface of the cartridge body for insertion of the magnetic head unit; a cover body for opening and closing the opening portion; and a central opening portion which allows at least the central portion of the magnetic disc to be faced external to the cartridge body.
- 2. A disc cartridge as set forth in claim 1, wherein the opening portion is positioned at the front of the insertion direction side into the magnetic disc apparatus of the cartridge body.
- 3. A disc cartridge as set forth in claim 1, wherein the cover body is rotatably supported with respect to the cartridge body so that it can be rotated in a direction parallel to the plane surface of the cartridge body, and is based by a biasing member in a direction to close the opening portion.
- 4. A disc cartridge as set forth in claim 3, wherein an engagement portion engaged with a cover body opening member provided at the magnetic disc apparatus side when the disc cartridge is inserted into the magnetic disc apparatus is provided at the cover body.
- 5. A disc cartridge as set forth in claim 2, wherein the cover body is rotatably supported with respect to the cartridge body so that it can be rotated in a direction perpendicular to a plane surface of the cartridge body, and is biased by a biasing member in a direction to close the opening portion.
- 6. A disc cartridge as set forth in claim 1, wherein an identification portion for identifying a type of magnetic disc accommodated within the cartridge body is provided at the cartridge body.
- 7. A disc cartridge as set forth in claim 1, further comprising:
a hub mechanism including a pair of holding members attached to the magnetic disc so that a peripheral edge of a central portion of the magnetic disc being positioned between the pair of holding members, and a metallic clamping member being attached to the pair of holding members and clamped by the disc rotating mechanism, wherein the pair of holding members are formed by a synthetic resin having substantially the same coefficient of thermal expansion as that of the disc substrate of the magnetic disc.
- 8. A disc cartridge as set forth in claim 1, wherein the synthetic resin has a coefficient of thermal expansion of 6.5×10−5 to 7.5×10−5 deg−1.
- 9. A disc cartridge as set forth in claim 1, wherein the control uneven pit trains are formed on at least one surface of the disc substrate of the first magnetic disc.
- 10. A disc cartridge as set forth in claim 1, wherein control signals are recorded on a flat surface of the surface portion where the plurality of flat recording tracks are provided of the first magnetic disc.
- 11. A disc cartridge as set forth in claim 1, wherein the information uneven pit trains and control uneven pit trains are formed on at least one surface of the disc substrate of the second magnetic disc.
- 12. A disc cartridge as set forth in claim 1, wherein:
information uneven pit trains are formed on at least one surface of the second disc substrate of the second magnetic disc and a magnetic layer is formed in a manner to include the plurality of bottom surfaces and upper surfaces of the information uneven pit trains, the magnetic layer being magnetized in the state where a magnetization direction of the magnetic layer portions on the bottom surfaces and that of the magnetic layer portions of the upper surfaces of the information uneven pit trains are different from each other to record information, the plurality of flat recording tracks being provided on the other surface of the disc substrate, and a magnetic layer covers the plurality of recording tracks.
Priority Claims (2)
Number |
Date |
Country |
Kind |
P08-165842 |
Jun 1996 |
JP |
|
P08-168019 |
Jun 1996 |
JP |
|
RELATED APPLICATIONS
[0001] This is a division of application Ser. No. 09/029,495, filed on Aug. 7th, 1998.
Divisions (1)
|
Number |
Date |
Country |
Parent |
09029495 |
Aug 1998 |
US |
Child |
10090107 |
Mar 2002 |
US |