Magnetic disc cartridge having a substrate with magnetized pit trains

Abstract

A magnetic disc apparatus using a magnetic disc adapted so that recording and/or reproduction are carried out by a magnetic head unit which undergoes floating force by air flow produced as the result of the fact that the magnetic disc is rotated serves to selectively carry out loading of a first disc cartridge within which there is accommodated a first magnetic disc adapted so that flat recording tracks are provided at a disc substrate formed by molding synthetic resin and a magnetic layer is provided in a manner to cover the recording tracks, and a second disc cartridge within which there is accommodated a second magnetic disc adapted so that information uneven pit trains are formed at a disc substrate formed by molding synthetic resin and a magnetic layer is formed in a manner to include bottom surfaces and upper surfaces of information uneven pit trains, the magnetic layer being magnetized in the state where magnetization direction of the magnetic layer portions on the bottom surfaces and that of the magnetic layer portions of the upper surfaces of information pit trains are different from each other so that information such as program, etc. are recorded. Thus, new program can be installed into computer only by exchange of the disc cartridge.

1 . A magnetic disc apparatus comprising: 
 a disc rotational operation mechanism for allowing a magnetic disc to undergo rotational operation;    a magnetic head unit comprising a magnetic head element for scanning a signal recording area of the magnetic disc caused to undergo rotational operation by the disc rotational operation mechanism along inner and outer circumferential directions and provided at a slider which undergoes floating force by air flow produced as the result of the fact that the magnetic disc is rotated; and    a cartridge loading portion adapted so that there is loaded a disc cartridge within which the magnetic disc caused to undergo rotational operation by the disc rotational operation mechanism is accommodated,    wherein there are selectively loaded, with respect to the cartridge portion, a first disc cartridge within which there is accommodated a first magnetic disc including a disc substrate formed by molding synthetic resin and adapted so that flat recording tracks are provided on at least one surface of the disc substrate and a magnetic layer is provided in a manner to cover the recording tracks, and a second disc cartridge within which there is accommodated a second magnetic disc including a disc substrate formed by molding synthetic resin and adapted so that information uneven pit trains are formed on at least one surface of the disc substrate and a magnetic layer is formed in a manner to include bottom surfaces and upper surfaces of the information uneven pit trains, the magnetic layer being magnetized so that magnetization direction of the magnetic layer portions on the bottom surfaces of the information uneven pit trains and that of the magnetic layer portions on the upper surfaces thereof are different from each other so that information are recorded on the second magnetic disc.    
     
     
         2 . A magnetic disc apparatus as set forth in  claim 1 , 
 wherein uneven pit trains for control where control signals for controlling positions with respect to the first disc of the magnetic head unit are recorded are formed on at least one surface of the disc substrate of the first magnetic disc.    
     
     
         3 . A magnetic disc apparatus as set forth in  claim 1 , 
 wherein control signals for controlling positions with respect to the first magnetic disc of the magnetic head unit are recorded on a flat surface of the surface portion where the recording tracks are provided of the first magnetic disc.    
     
     
         4 . A magnetic disc apparatus as set forth in  claim 1 , 
 wherein guard band portions of recessed lines are provided along the recording tracks on the disc substrate of the first magnetic disc.    
     
     
         5 . A magnetic disc apparatus as set forth in  claim 1 , 
 wherein the information pit trains and uneven pit trains for control where control signals for controlling positions with respect to the second disc of the magnetic head unit are recorded are formed on at least one surface of the disc substrate of the second magnetic disc.    
     
     
         6 . A magnetic disc apparatus as set forth in  claim 1 , 
 wherein information uneven pit trains are formed at one surface of the disc substrate of the second magnetic disc and a magnetic layer is formed in a manner to include bottom surfaces and upper surfaces of the information uneven pit trains, the magnetic layer being magnetized so that magnetization direction of the magnetic layer portions on the bottom surfaces of the information pit trains and that of the magnetic layer portions on the upper surfaces thereof are different from each other, flat recording tracks being provided on the other surface of the disc substrate, a magnetic layer being provided in a manner to cover the recording tracks.    
     
     
         7 . A magnetic disc apparatus as set forth in  claim 1 , 
 wherein the magnetic disc apparatus comprises a base adapted so that at least the disc rotational operation mechanism and the magnetic head unit are attached and a cartridge loading portion is provided, and a casing within which the base is accommodated, and    wherein an insertion/withdrawal hole of the disc cartridge is provided at the casing, and the disc cartridge inserted into the casing through the insertion/withdrawal hole is loaded with respect to the cartridge loading portion.    
     
     
         8 . A magnetic disc apparatus as set forth in  claim 7 , 
 wherein the magnetic disc apparatus further comprises, within the casing, a cover opening/closing mechanism for allowing a cover body which opens or closes an opening portion provided at the disc cartridge to undergo opening operation.    
     
     
         9 . A magnetic disc apparatus as set forth in  claim 7 , 
 wherein the magnetic disc apparatus further comprises a cartridge discrimination mechanism for discriminating kind of the disc cartridge loaded with respect to the cartridge loading portion.    
     
     
         10 . A magnetic disc adapted so that recording and/or reproduction are carried out by a magnetic head unit comprising a magnetic head element provided at a slider which undergoes floating force by air flow produced as the result of the fact that the magnetic disc is rotated, 
 the magnetic disc comprising: 
 a disc substrate formed by molding synthetic resin and adapted so that information uneven pit trains where information are recorded and uneven pit trains for control where control signals for controlling positions of the magnetic head unit are recorded are formed at least one surface; and  
 a magnetic layer formed in a manner to include bottom surfaces and upper surfaces of the information uneven pit trains and the control uneven pit trains,  
 wherein the magnetic layer is magnetized so that magnetization direction of the magnetic layer portions on bottom surfaces and that of the magnetic layer portion on upper surfaces of the information uneven pit trains are different from each other so that information are recorded, and the magnetic layer is further magnetized so that magnetization direction of the magnetic layer portions on bottom surfaces and that of the magnetic layer portions of upper surfaces of the control uneven pit trains are different from each other so that control signals are recorded.  
   
     
     
         11 . A magnetic disc as set forth in  claim 10 , 
 wherein the information uneven pit trains where information are recorded and the control uneven pit trains where control signals for controlling positions of the magnetic head unit are recorded are formed on both surfaces of the disc substrate.    
     
     
         12 . A magnetic disc comprising: 
 a disc substrate adapted so that information uneven pit trains where information are recorded and uneven pit trains for control where control signals for controlling positions of the magnetic head unit are recorded are formed on one surface, and flat recording tracks are provided at the other surface;    a magnetic layer formed in a manner to include bottom surfaces and upper surfaces of the information uneven pit trains and the control uneven pit trains formed on one surface of the disc substrate; and    a magnetic layer formed in a manner to cover recording tracks formed on the other surface of the disc substrate,    wherein the magnetic layer formed on one surface of the disc substrate is magnetized so that magnetization direction of the magnetic layer portions on the bottom surfaces and that of the magnetic layer portions on the upper surfaces of the information pit trains are different from each other so that information are recorded, and that magnetic layer portion is magnetized so that magnetization direction of the magnetic layer portions on the bottom surfaces and that of the magnetic layer portions of the upper surfaces of the control uneven pit trains are different from each other so that control signals are recorded.    
     
     
         13 . A magnetic disc apparatus as set forth in  claim 12 , 
 wherein uneven pit trains for control where control signals for controlling position of the magnetic head unit are recorded are formed at the other surface of the disc substrate.    
     
     
         15 . A magnetic disc as set forth in  claim 10 , 
 wherein guard band portions of recessed lines are provided on the disc substrate along the information pit trains.    
     
     
         16 . A magnetic disc as set forth in  claim 10 , 
 which comprises a hub mechanism including a pair of holding members attached to the disc substrate in the state where the peripheral edge of a center hole provided at the central portion of the disc substrate is put therebetween, and a clamping member of steel attached to the holding members and clamped by a disc rotational operation mechanism,    wherein the pair of holding members of the hub mechanism are formed by synthetic resin having substantially the same coefficient of thermal expansion as that of the disc substrate.    
     
     
         17 . A magnetic disc as set forth in  claim 16 , 
 wherein the disc substrate and the pair of holding members are formed by synthetic resin having coefficient of thermal expansion of 6.5 to 7.5×10 −5  deg −1 .    
     
     
         18 . A disc cartridge comprising: 
 a cartridge body within which there is rotatably accommodated either one of a first magnetic disc adapted so that flat recording tracks are provided at least at one surface of a disc substrate formed by molding synthetic resin and a magnetic layer is provided in a manner to cover the recording tracks, the first magnetic disc being adapted so that recording and/or reproduction are carried out by a magnetic head unit comprising a magnetic head element provided at a slider which undergoes floating force by air flow produced as the result of the fact that the magnetic disc is rotated, and a second magnetic disc adapted so that there are provided a disc substrate formed by molding synthetic resin and such that information uneven pit trains where information are recorded and uneven pit trains for control where control signals for controlling positions of the magnetic head unit are recorded are formed on at least one surface, and a magnetic layer formed in a manner to include bottom surfaces and upper surfaces of the information uneven pit trains and the control uneven pit trains, the magnetic layer being magnetized in the state where 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 so that information are recorded, the magnetic layer being further magnetized in the state where magnetization direction of the magnetic layer portions on the bottom surfaces and that of the magnetic layer portions of the upper surfaces of the control uneven pit trains are different from each other so that control signals are recorded, the second magnetic disc being adapted so that recording and/or reproduction are carried out by a magnetic head unit comprising a magnetic head element provided at a slider which undergoes floating force by air flow produced as the result of the fact that the magnetic disc is rotated;    an opening portion for insertion of the magnetic head unit provided at one side surface of the cartridge body;    a cover body for opening/closing the opening portion; and    a central opening portion which allows at least the central portion of the magnetic disc to be faced to the external.    
     
     
         19 . A disc cartridge as set forth in  claim 18 , 
 wherein the opening portion is provided at the front of insertion direction side into the magnetic disc apparatus of the cartridge body.    
     
     
         20 . A disc cartridge as set forth in  claim 18 , 
 wherein the cover body is rotatably supported with respect to the cartridge body so that it can be rotated in a direction in parallel to plane surface of the cartridge body, and is biased by a biasing member in a direction to close the opening portion.    
     
     
         21 . A disc cartridge as set forth in  claim 20 , 
 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.    
     
     
         22 . A disc cartridge as set forth in  claim 19 , 
 wherein the cover body is rotatably supported with respect to the cartridge body so that it can be rotated in a direction perpendicular to plane surface of the cartridge body, and is biased by a biasing member in a direction to close the opening portion.    
     
     
         23 . A disc cartridge as set forth in  claim 18 , 
 wherein a discrimination portion for discriminating kind of the magnetic disc accommodated within the cartridge body is provided at the cartridge body.    
     
     
         24 . A disc cartridge as set forth in  claim 18 , 
 which comprises a hub mechanism including a pair of holding members attached to the magnetic disc in the state where the peripheral edge of a center hole provided at the central portion of the magnetic disc is put or held therebetween, and a clamping member of steel attached to the holding members and clamped by the disc rotational operation mechanism,    wherein the pair of holding members of the hub mechanism are formed by synthetic resin having substantially the same coefficient of thermal expansion as that of the disc substrate constituting the magnetic disc.    
     
     
         25 . A disc cartridge as set forth in  claim 24 , 
 wherein the disc substrate and the pair of holding members are formed by synthetic resin having coefficient of thermal expansion of 6.5 to 7.5×10 −5  deg −1 .    
     
     
         26 . A disc cartridge as set forth in  claim 18 , 
 wherein uneven pit trains for control where control signals for controlling position with respect to the first disc of the magnetic head unit are recorded are formed at least at one surface of the disc substrate of the first magnetic disc.    
     
     
         27 . A disc cartridge as set forth in  claim 18 , 
 wherein control signals for controlling position with respect to the first magnetic disc of the magnetic head unit are recorded on a flat surface of the surface portion where recording tracks are provided of the first magnetic disc.    
     
     
         28 . A disc cartridge as set forth in  claim 18 , 
 wherein the information pit trains and uneven pit trains for control where control signals for controlling positions with respect to the second disc of the magnetic head unit are recorded are formed at least at one surface of the disc substrate of the second magnetic disc.    
     
     
         29 . A disc cartridge as set forth in  claim 18 , 
 wherein information uneven pit trains are formed at one surface of the disc substrate of the second magnetic disc and a magnetic layer is formed in a manner to include bottom surfaces and upper surfaces of the information uneven pit trains, the magnetic layer being magnetized in the state where 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 pit trains are different from each other so that information are recorded, flat recording tracks being provided on the other surface of the disc substrate, a magnetic layer being provided in a manner to cover the recording tracks.