Thin film magnetic head and magnetic disk apparatus using the same

Abstract

A thin film magnetic head which can suppress magnetic saturation at opposite ends of width of a narrow track width to reduce the amount of recording side-fringing onto a recording medium and which can assure a necessary recording magnetic field satisfactorily. Also a magnetic disk apparatus using the head. A second magnetic yoke has a magnetic gap depth over which the spacing of a magnetic gap keeps substantially equal toward a rear portion of the second magnetic yoke, starting at the tip of a second magnetic pole and the spacing between a first magnetic yoke and the second magnetic yoke is increased toward the rear portion, starting at a position corresponding to the magnetic gap depth. The second magnetic pole of the second magnetic yoke has in the track width direction a width for recording a signal on a track width of the recording medium. The width keeps constant over a predetermined length toward the rear portion, starting at the second magnetic pole tip and spreads monotonically toward the rear, starting at a position corresponding to the predetermined length. The predetermined length terminating in the spread start position of the width of the second magnetic yoke is set to be shorter than the magnetic gap depth.

What is claimed is:  
     
       1. A thin film magnetic head comprising: 
       a first magnetic yoke having a first magnetic pole facing a magnetic recording medium;  
       a second magnetic yoke having a second magnetic pole so disposed as to define a magnetic gap between the first magnetic pole and the second magnetic pole and forming at a rear portion of the second magnetic yoke a magnetic circuit which magnetically short-circuits to said first magnetic yoke;  
       a conductor coil formed between said first and second magnetic yokes; and  
       an insulating layer for insulating said conductor coil from said first and second magnetic yokes,  
       wherein said second magnetic yoke has a magnetic gap depth over which the spacing of the magnetic gap defined between said first and second magnetic yokes keeps substantially equal toward the rear portion of said second magnetic yoke, starting at the tip of said second magnetic pole and, the spacing between said first and second magnetic yokes is increased toward the rear portion, starting at a position corresponding to the magnetic gap depth from the second magnetic pole tip, to house said conductor coil and said insulating layer;  
       said second magnetic pole of said second magnetic yoke has a width in the track width direction for recording a signal on a track width of said recording medium;  
       said width keeps constant over a predetermined length toward the rear portion, starting at the second magnetic pole tip and spreads monotonically toward the rear, starting at a spread start position corresponding to the predetermined length from the second magnetic pole tip; and  
       said predetermined length terminating in the spread start position of said width of said second magnetic yoke is shorter than said magnetic gap depth.  
     
     
       2. A thin film magnetic head according to  claim 1 , wherein by adjusting said predetermined length terminating in said spread start position, the amount of induced write magnetic flux going round directly to said first and second magnetic yokes without passing through said recording medium is adjusted within a region of said magnetic gap depth so that saturation of the induced magnetic flux at opposite ends of track width of said second magnetic pole may be suppressed to reduce the amount of spreading of a recording magnetization pattern at opposite ends of track width on said recording medium. 
     
     
       3. A thin film magnetic head according to  claim 2 , wherein said predetermined length up to said spread start position is adjusted during photomask preparation or photomask setting. 
     
     
       4. A magnetic disk apparatus comprising: 
       the thin film magnetic head as recited in  claim 2 ;  
       a pneumatic bearing floating slider in which said magnetic head is formed;  
       an arm for supporting said slider;  
       a controller for moving said arm to a predetermined position on a magnetic recording medium; and  
       a signal processor for processing a recording/reproduction signal of said magnetic head.  
     
     
       5. A thin film magnetic head according to  claim 1 , wherein said first magnetic yoke has grooves to define said first magnetic pole at a part of said first magnetic yoke facing said second magnetic pole. 
     
     
       6. A thin film magnetic head according to  claim 5 , wherein said second magnetic pole and said grooves in said first magnetic yoke are formed by trimming through the same trimming process. 
     
     
       7. A thin film magnetic head according to  claim 5 , wherein a part of said second magnetic pole facing said first magnetic pole includes a magnetic material having a higher saturation flux density than that of the remaining part of said second magnetic pole. 
     
     
       8. A thin film magnetic head according to  claim 7 , wherein said first magnetic yoke inclusive of said first magnetic pole includes a magnetic material having a higher saturation flux density than that of said remaining part of said second magnetic pole. 
     
     
       9. A thin film magnetic head according to  claim 1 , wherein a part of said first magnetic yoke facing said second magnetic pole projects toward said second magnetic pole, said projecting part of said first magnetic yoke constituting said first magnetic pole. 
     
     
       10. A thin film magnetic head according to  claim 9 , wherein a part of said second magnetic pole facing said first magnetic pole includes a material having a higher saturation flux density than that of the remaining part of said second magnetic pole. 
     
     
       11. A thin film magnetic head according to  claim 10 , wherein said projecting first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of said first magnetic yoke. 
     
     
       12. A thin film magnetic head according to  claim 1 comprising: 
       
         a first magnetic yoke having a first magnetic pole facing a magnetic recording medium;  
       
         a second magnetic yoke having a second magnetic pole so disposed as to define a magnetic gap between the first magnetic pole and the second magnetic pole and forming at a rear portion of the second magnetic yoke a magnetic circuit which magnetically short - circuits to said first magnetic yoke;    
       
         a conductor coil formed between said first and second magnetic yokes; and  
       
       
         an insulating layer for insulating said conductor coil from said first and second magnetic yokes,  
       
       
         wherein said second magnetic yoke has a magnetic gap depth over which the spacing of the magnetic gap defined between said first and second magnetic yokes keeps substantially equal toward the rear portion of said second magnetic yoke, starting at the tip of said second magnetic pole and, the spacing between said first and second magnetic yokes is increased toward the rear portion, starting at a position corresponding to the magnetic gap depth from the second magnetic pole tip, to house said conductor coil and said insulating layer;  
       
       
         said second magnetic pole of said second magnetic yoke has a width in the track width direction for recording a signal on a track width of said recording medium;  
       
       
         said width keeps constant over a predetermined length toward the rear portion, starting at the second magnetic pole tip and spreads monotonically toward the rear, starting at a spread start position corresponding to the predetermined length from the second magnetic pole tip;  
       
       
         said predetermined length terminating in the spread start position of said width of said second magnetic yoke is shorter than said magnetic gap depth; and 
       
       further comprising a shield disposed on the side of said first magnetic yoke opposite to said second magnetic yoke and a read head interposed between said first magnetic yoke and said shield, said first magnetic yoke including a third magnetic yoke disposed to face said second magnetic yoke and a fourth magnetic yoke disposed to face said read head while being electrically insulated from said third magnetic yoke.  
     
     
       13. A thin film magnetic head according to  claim 12 , wherein a part of said third magnetic yoke facing said second magnetic pole projects toward said second magnetic pole, said projecting part constituting said first magnetic pole. 
     
     
       14. A thin film magnetic head according to  claim 13 , wherein a part of said second magnetic pole facing said first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of the remaining part of said second magnetic pole. 
     
     
       15. A thin film magnetic head according to  claim 14 , wherein said projecting first magnetic yoke includes a magnetic material having a higher saturation magnetic flux density than that of said third magnetic yoke. 
     
     
       16. A magnetic disk apparatus comprising: 
       the thin film magnetic head as recited in  claim 1   2 ;  
       a pneumatic bearing floating slider in which said magnetic head is formed;  
       an arm for supporting said slider;  
       a controller for moving said arm to a predetermined position on a magnetic recording medium; and  
       a signal processor for processing a recording/reproduction signal of said magnetic head.  
     
     
       17. A magnetic disk apparatus according to  claim 16 , wherein said first magnetic yoke has grooves to define said first magnetic pole at a part of said first magnetic yoke facing said second magnetic pole. 
     
     
       18. A magnetic disk apparatus according to  claim 17 , wherein a part of said second magnetic pole facing said first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of the remaining part of said second magnetic pole. 
     
     
       19. A magnetic disk apparatus according to  claim 18 , wherein said first magnetic yoke inclusive of said first magnetic pole has a higher saturation magnetic flux density than that of said remaining part of said second magnetic pole. 
     
     
       20. A magnetic disk apparatus according to  claim 19 , wherein a part of said second magnetic pole facing said first magnetic pole includes a material having a higher saturation magnetic flux density than that of the remaining part of said second magnetic pole. 
     
     
       21. A magnetic disk apparatus according to  claim 20 , wherein said projecting first magnetic pole has a magnetic material having a higher saturation magnetic flux density than that of said first magnetic yoke. 
     
     
       22. A magnetic disk apparatus according to  claim 16 , further comprising a shield on the side of said first magnetic yoke opposite to said second magnetic yoke and a read head interposed between said first magnetic yoke and said shield, said first magnetic yoke including a third magnetic yoke disposed to face said second magnetic yoke and a fourth magnetic yoke disposed to face said read head while being electrically insulated from said third magnetic yoke. 
     
     
       23. A magnetic disk apparatus according to  claim 22 , wherein a part of said third magnetic yoke facing said second magnetic pole projects toward said second magnetic pole, said projecting part constituting said first magnetic pole. 
     
     
       24. A magnetic disk apparatus according to  claim 23 , wherein a part of said second magnetic pole facing said first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of the remaining part of said second magnetic pole. 
     
     
       25. A magnetic disk apparatus according to  claim 24 , wherein said projecting first magnetic pole has a magnetic material having a higher saturation magnetic flux density than that of said third magnetic yoke. 
     
     
       26. A magnetic disk apparatus according to  claim 17 , wherein said second magnetic pole and said grooves in said first magnetic yoke are formed by trimming through a same trimming process. 
     
     
       27. A magnetic disk apparatus according to  claim 16 , wherein a part of said first magnetic yoke facing said second magnetic pole projects toward said second magnetic pole, said projecting part of said first magnetic yoke constituting said first magnetic pole. 
     
     
       28. A magnetic read and write head comprising: 
       
         a lower magnetic shield layer;  
       
         a magnetoresistive - effect sensor such as a MR head or a GMR head formed on said lower magnetic shield layer via an insulating layer;    
         an upper magnetic shield layer formed on said magnetoresistive - effect sensor and said lower magnetic shield layer via another insulating layer;    
       
         a conductor coil formed on said upper magnetic shield layer, said upper magnetic shield layer acting as a first magnetic yoke;  
       
         a second magnetic yoke formed on said conductor coil and said first magnetic yoke via a further insulating layer and forming a magnetic gap between an end portion of said first magnetic yoke and said second magnetic yoke and forming at a rear portion of said second magnetic yoke a magnetic circuit which magnetically short - circuits to said first magnetic yoke;    
       
         wherein said first and second magnetic yokes define a magnetic gap depth over which said magnetic gap keeps a substantially equal spacing beginning at ends of the first and second magnetic yokes and toward the rear;  
       
       
         wherein said second magnetic yoke has a width which is constant over a predetermined length beginning at the end of said second magnetic yoke and toward said rear portion and said width increases toward said rear portion from a spread start position corresponding to said predetermined length from the end of said second magnetic yoke; and  
       
       
         wherein said predetermined length of said second magnetic yoke is shorter than said magnetic gap depth. 
       
     
     
       29. A magnetic read and write head according to  claim 28 , wherein said first magnetic yoke has grooves to define a first magnetic pole at a part of said first magnetic yoke facing said second magnetic yoke. 
     
     
       30. A thin film magnetic head according to  claim 29 , wherein a part of said second magnetic yoke facing said first magnetic pole and said grooves in said first magnetic yoke are formed by trimming through the same trimming process. 
     
     
       31. A magnetic read and write head according to  claim 29 , wherein a part of an end portion of said second magnetic yoke facing said first magnetic pole includes a magnetic material having a higher saturation flux density than that of the remaining part of said end portion of said second magnetic yoke. 
     
     
       32. A thin film magnetic head according to  claim 31 , wherein said first magnetic yoke inclusive of said first magnetic pole includes a magnetic material having a higher saturation flux density than that of said remaining part of said end portion of said second magnetic pole. 
     
     
       33. A magnetic read and write head according to  claim 28 , wherein a part of the end portion of said first magnetic yoke facing said second magnetic yoke projects toward said second magnetic pole, said projecting part of said first magnetic yoke constituting said first magnetic pole. 
     
     
       34. A magnetic read and write head according to  claim 33 , wherein a part of said second magnetic pole facing said first magnetic pole includes a material having a higher saturation flux density than that of the remaining part of said second magnetic yoke. 
     
     
       35. A magnetic read and write head according to  claim 34 , wherein said projecting first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of said first magnetic yoke. 
     
     
       36. A magnetic read and write head comprising: 
       
         a lower magnetic shield layer;  
       
         a magnetoresistive - effect sensor such as a MR head or a GMR head formed on said lower magnetic shield layer via an insulating layer;    
         a first magnetic layer formed on said magnetoresistive - effect sensor and said lower magnetic shield layer via another insulating layer;    
       
         a second magnetic layer formed on said first magnetic layer via an insulating layer;  
       
       
         a conductor coil formed on said second magnetic layer, said second magnetic layer acting as a first magnetic yoke;  
       
         a second magnetic yoke formed on said conductor coil and said first magnetic yoke via a further insulating layer and forming a magnetic gap between a tip portion of said first magnetic yoke and said second magnetic yoke and forming at a rear portion of said second magnetic yoke a magnetic circuit which magnetically short - circuits to said first magnetic yoke;    
       
         wherein said first and second magnetic yokes define a magnetic gap depth over which said magnetic gap keeps a substantially equal spacing beginning at ends of the first and second magnetic yokes and toward the rear portion thereof;  
       
       
         wherein said second magnetic yoke has a width which is constant over a predetermined length beginning at the end of the second magnetic yoke toward said rear portion and said width increases toward the rear from a spread start position corresponding to said predetermined length from the end of said second magnetic yoke; and  
       
       
         wherein said predetermined length of said second magnetic yoke is shorter than said magnetic gap depth. 
       
     
     
       37. A magnetic read and write head according to  claim 36 , wherein said first magnetic yoke has grooves to define a first magnetic pole at a part of said first magnetic yoke facing said second magnetic yoke. 
     
     
       38. A magnetic read and write head according to  claim 37 , wherein a part of said second magnetic yoke facing said first magnetic pole and said grooves in said first magnetic yoke are formed by trimming through the same trimming process. 
     
     
       39. A magnetic read and write head according to  claim 37 , wherein a part of an end portion of said second magnetic yoke facing said first magnetic pole includes a magnetic material having a higher saturation flux density than that of the remaining part of said end portion of said second magnetic yoke. 
     
     
       40. A thin film magnetic head according to  claim 39 , wherein said first magnetic yoke inclusive of said first magnetic pole includes a magnetic material having a higher saturation flux density than that of said remaining part of said end portion of said second magnetic yoke. 
     
     
       41. A magnetic read and write head according to  claim 36 , wherein a part of the end portion of said first magnetic yoke facing said second magnetic yoke projects toward said second magnetic yoke, said projecting part of said first magnetic yoke constituting a first magnetic yoke. 
     
     
       42. A thin film magnetic head according to  claim 41 , wherein a part of said second magnetic yoke facing said first magnetic pole includes a material having a higher saturation flux density than that of the remaining part of said second magnetic yoke. 
     
     
       43. A thin film magnetic head according to  claim 42 , wherein said projecting first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of said first magnetic yoke. 
     
     
       44. A magnetic read and write head comprising: 
       
         a lower magnetic shield layer;  
       
         a magnetoresistive - effect sensor such as a MR head or a GMR head formed on said lower magnetic shield layer via another insulating layer;    
         a first magnetic layer formed on said magnetoresistive - effect sensor and said lower magnetic shield layer via another insulating layer;    
       
         a second magnetic layer formed on said first magnetic layer via a further insulating layer;  
       
       
         a conductor coil formed on said second magnetic layer, said second magnetic layer acting as a first magnetic yoke;  
       
         a second magnetic yoke formed on said conductor coil and said first magnetic yoke via still a further insulating layer and forming a magnetic gap between an end portion of said first magnetic yoke and said second magnetic yoke and forming at a rear portion of said second magnetic yoke a magnetic circuit which magnetically short - circuits to said first magnetic yoke;    
       
         wherein said first and second magnetic yokes define a predetermined depth of said magnetic gap beginning at ends of the first and second magnetic yokes and toward the rear thereof,  
       
       
         wherein said second magnetic yoke has a width which is constant over a predetermined length beginning at the end of said second magnetic yoke and toward the rear thereof and said width increases toward the rear thereof from a spread start position corresponding to said predetermined length from the end of said second magnetic yoke; and  
       
       
         wherein said predetermined length of said second magnetic yoke is shorter than said magnetic gap depth. 
       
     
     
       45. A magnetic read and write head according to  claim 44 , wherein said first magnetic yoke has grooves to define a first magnetic pole at a part of said first magnetic yoke facing said second magnetic yoke. 
     
     
       46. A thin film magnetic head according to  claim 45 , wherein a part of said second magnetic yoke facing said first magnetic pole and said grooves in said first magnetic yoke are formed by trimming through the same trimming process. 
     
     
       47. A magnetic read and write head according to  claim 45 , wherein a part of an end portion of said second magnetic yoke facing said first magnetic pole includes a magnetic material having a higher saturation flux density than that of the remaining part of said end portion of said second magnetic yoke. 
     
     
       48. A magnetic read and write head according to  claim 47 , wherein said first magnetic yoke inclusive of said first magnetic pole includes a magnetic material having a higher saturation flux density than that of said remaining part of said end portion of said second magnetic yoke. 
     
     
       49. A magnetic read and write head according to  claim 44 , wherein a part of the end portion of said first magnetic yoke facing said second magnetic pole projects toward said second magnetic yoke, said projecting part of said first magnetic yoke constituting a first magnetic pole. 
     
     
       50. A magnetic read and write head according to  claim 49 , wherein a part of said second magnetic yoke facing said first magnetic pole includes a material having a higher saturation flux density than that of the remaining part of said second magnetic yoke. 
     
     
       51. A magnetic read and write head according to  claim 50 , wherein said projecting first magnetic pole includes a magnetic material having a higher saturation magnetic flux density than that of said first magnetic yoke.