Magnetic recording/reproducing apparatus

Abstract

A sync signal time difference detection circuit ( 7 ) detects a time difference of reproduced sync signals reproduced by a first head ( 100 ) and a second head ( 101 ) having different azimuth angles. Rotation of a capstan motor ( 2 ) is controlled in accordance with sync signal time difference information output from the sync signal time difference detection circuit ( 7 ), thereby performing a highly accurate tracking control not affected by jitter or eccentricity.

1 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first and second heads having azimuth angles different from each other and arranged along a periphery of said rotary drum, for recording data in a track oblique to a longitudinal direction of a magnetic tape, and for reproducing the data on said track;    a sync-signal generator for generating a recording synchronizing signal to be recorded on said magnetic tape, and for outputting said recording synchronizing signal to said first and second heads;    a sync-signal time difference detector for detecting a time difference between reproduced synchronizing signals reproduced from said magnetic tape and output from said first and second heads, respectively; and    a capstan-motor controller for controlling rotation of a capstan motor advancing said magnetic tape based on said time difference output from said sync-signal time difference detector,    wherein said sync-signal generator outputs said recording synchronizing signal to said first and second heads substantially simultaneously.    
     
     
         2 . The magnetic recording and reproducing apparatus according to  claim 1 , 
 wherein said sync-signal generator outputs a recording synchronizing signal for each of “n” number of sync-blocks formed by dividing said track into “n” (“n” represents an integer of 1 or larger), and    wherein said first and second heads are arranged along said periphery by a distance generally equal to an integral multiple of a length of each of said sync blocks of said track on said magnetic tape.    
     
     
         3 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first and second heads having azimuth angles different from each other and arranged along a periphery of said rotary drum, for recording data in a track oblique to a longitudinal direction of a magnetic tape, and for reproducing the data on said track;    a sync-signal generator for generating first and second recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first and second recording synchronizing signals to said first and second heads, respectively;    a sync-signal time difference detector for detecting a time difference between first and second reproduced synchronizing signals output from said first and second heads, respectively;    a reproduction PLL circuit for outputting a reproduction clock in synchronism with a rate of reproduced signals output from said second head; and    a capstan-motor controller for controlling a rotation of a capstan motor advancing said magnetic tape based on said time difference output from said sync-signal time difference detector,    wherein said sync-signal generator outputs said first recording synchronizing signal after said second recording synchronizing signal with delay of a predetermined time (T 0 ), and    wherein said sync-signal time difference detector detects, as said time difference between said first and said second reproduced synchronizing signals, a time difference between a reproduced pseudo-synchronizing signal and said first reproduced synchronizing signal, said reproduced pseudo-synchronizing signal being a signal delayed from said second reproduced synchronizing signal by a period equivalent to a number of said reproduction clock corresponding to said predetermined time (T 0 ).    
     
     
         4 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first and second heads having azimuth angles different from each other and arranged along a periphery of said rotary drum, for recording data in a track oblique to a longitudinal direction of a magnetic tape and for reproducing the data on said tracks;    a sync-signal generator for generating first and second recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first and second recording synchronizing signals to said first and second heads, respectively;    a sync-signal time difference detector for detecting a time difference between first and second reproduced synchronizing signals reproduced from said magnetic tape and for outputting said first and second reproduced synchronizing signals from said first and said second heads, respectively;    a reproduction PLL circuit for outputting a reproduction clock in synchronism with a rate of a reproduced signal output by said second head; and    a capstan motor controller for controlling rotation of a capstan motor advancing said magnetic tape based on said time difference between said reproduced synchronizing signals output from said sync-signal time difference detector,    wherein said sync-signal generator is operable selectively to output said first and second recording synchronizing signals substantially simultaneously or to output said first recording synchronizing signal with delay of a predetermined time (T 0 ) from said second recording synchronizing signal, and    wherein said sync-signal time difference detector detects said time difference between said first and second reproduced synchronizing signals if said time difference between said first and second reproduced synchronizing signals is not longer than a predetermined time (Tw) and detects, as said time difference between said first and second reproduced synchronizing signals, a time difference between a reproduced pseudo-synchronizing signal and said first reproduced synchronizing signal if said time difference is not longer than another predetermined time (T 0 +Tw), said reproduced pseudo-synchronizing signal being a signal delayed from said second reproduced synchronizing signal by a period equivalent to a number of reproduction clock corresponding to said predetermined time (T 0 ).    
     
     
         5 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first, second, and third heads for recording data in a track oblique to a longitudinal direction of a magnetic tape and for reproducing the data on said track, said first and second heads having azimuth angles different from each other, said third head having a same azimuth angle as said first head;    a sync-signal generator for generating first, second, and third recording synchronizing signals to be recorded on said magnetic tape and for outputting said first, second, and third recording synchronizing signals to said first, second, and third heads, respectively;    a sync-signal time difference detector for detecting a first time difference between first and second reproduced synchronizing signals reproduced from said magnetic tape and for output said first and second reproduced synchronizing signals from said first and second heads, respectively, and for detecting a second time difference between said second reproduced synchronizing signal and a third reproduced synchronizing signal output from said third head; and    a capstan motor controller for controlling rotation of a capstan motor based on said first and said second time differences,    wherein said sync-signal generator outputs said first and second recording synchronizing signals substantially when said first head is in recording operation, and said second and third recording synchronizing signals substantially simultaneously when said third head is in recording operation.    
     
     
         6 . The magnetic recording and reproducing apparatus according to  claim 5 , 
 wherein said sync-signal generator outputs said first, second, and third recording synchronizing signals for each “n” number (“n” represents an integer of 1 or larger) of sync blocks formed by dividing a track into “n”,    wherein said first and second heads are arranged along said periphery by a distance therebetween substantially equal to an integral multiple of a length of each of said sync blocks of said track on said magnetic tape, and    wherein said second and third heads are arranged along said periphery by a distance substantially equal to an integral multiple of a length of each of said sync blocks of said track on said magnetic tape.    
     
     
         7 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first, second, and third heads for recording data in a track oblique to a longitudinal direction of a magnetic tape and for reproducing the data in said track, said first and second heads having azimuth angles different from each other, said third head having a same azimuth angle as said first head, said first, second, and third head being arranged along a periphery of said rotary drum;    a sync-signal generator for generating first, second, and third recording synchronizing signals to be recorded on said magnetic tape and for outputting said first, second, and third recording synchronizing signals to said first, second, and third heads, respectively;    a sync-signal time difference detector for detecting a first time difference between first and second reproduced synchronizing signals output from said first and second heads and reproduced from said magnetic tape, respectively, and for detecting a second time difference between said second reproduced synchronizing signal and a third reproduced synchronizing signal output from said third head; and    a reproduction PLL circuit for outputting a reproduction clock in synchronism with a rate of a reproduced signal output from said second head; and    a capstan-motor controller for controlling rotation of a capstan motor based on said first, second, and third time differences,    wherein said sync-signal generator outputs said first recording synchronizing signal after said second recording synchronizing signal with delay of a predetermined time (T 0 ), and outputs said third recording synchronizing signal after said second recording synchronizing signal with delay of a predetermined time (T 1 ), and    wherein said sync-signal time difference detector operable to 
 detect, as said first time difference, a time difference between a first reproduced pseudo-synchronizing signal and said first reproduced synchronizing signal when said first head is in a reproducing operation, said first reproduced pseudo-synchronizing signal being a signal delayed from said second reproduced synchronizing signal by a period equivalent to a number of said reproduction clock corresponding to said predetermined time (T 0 ), and  
 detect, as said first time difference, a time difference between a second reproduced pseudo-synchronizing signal and said third reproduced synchronizing signal when said third head is in a reproducing operation, said second reproduced pseudo-synchronizing signal being a signal delayed from said second reproduced synchronizing signal by a period equivalent to a number of said reproduction clock corresponding to said predetermined time (T 1 ).  
   
     
     
         8 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first, second, third, and fourth heads arranged along a periphery of said rotary drum, said first and third heads having same azimuth angles, said first and third heads recording and reproducing data in first and third tracks oblique to a longitudinal direction of a magnetic tape, respectively, said first and third heads reproducing the data in said first and third tracks, respectively, said second and fourth heads having same azimuth angles different from said azimuth angles of said first and third heads, said second and fourth heads recording data in second and fourth tracks oblique to the longitudinal direction of said magnetic tape, respectively, said second and fourth heads reproducing data in second and fourth tracks oblique to the longitudinal direction of said magnetic tape, respectively;    a sync-signal generator for generating said first to fourth recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first to fourth recording synchronizing signals to said first to fourth heads, respectively;    a sync-signal time difference detector for detecting a first time difference between first and second reproduced synchronizing signals output from said first and second heads and reproduced from said magnetic tape, respectively, and for detecting a second time difference between third and fourth reproduced synchronizing signals output from said third and fourth heads, respectively;    a track-number detector for detecting track numbers of tracks scanned by said first to fourth heads, respectively; and    a capstan-motor controller for controlling rotation of a capstan motor advancing said magnetic tape based on said first and second time differences output from said sync-signal time difference detector to control advancement of said magnetic tape according to said track numbers detected by said track-number detector so that said first to fourth heads scan said first to fourth tracks, respectively, during a normal reproducing operation.    
     
     
         9 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first to fourth heads, said first and third heads having same azimuth angles, said first and third heads recording data in first and third tracks oblique to a longitudinal direction of a magnetic tape, respectively, said first and third heads reproducing data in said first and third tracks, respectively, said second and fourth heads having azimuth angles different from said azimuth angles of said first and third heads, said second and fourth heads recording data in second and fourth tracks oblique to the longitudinal direction of said magnetic tape, respectively, said second and fourth heads reproducing data in said second and fourth tracks, respectively;    a sync-signal generator for generating first to fourth recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first to fourth recording synchronizing signals to said first to fourth heads, respectively;    a sync-signal time difference detector for detecting a first time difference between first and second reproduced synchronizing signals output from said first and second heads reproduced from said magnetic tape, respectively, and for detecting a second time difference between third and fourth reproduced synchronizing signals output from said third and fourth heads, respectively;    a capstan-motor controller operable to advance said magnetic tape at a normal speed and a speed different from said normal speed;    a track-number detector for detecting track numbers of tracks being scanned by said first to fourth heads, respectively; and    a tracking-position detector for detecting a target tracking position for each of said first to fourth track corresponding to said first to fourth heads, respectively, based on said first and second time differences and said track numbers output by said track-number detector.    
     
     
         10 . The magnetic recording and reproducing apparatus according to  claim 9 , wherein said tracking position detector detects, as said target tracking position, a middle value between maximum and minimum values of said first and second time differences.  
     
     
         11 . The magnetic recording and reproducing apparatus according to  claim 9 , wherein said tracking-position detector detects, as said target tracking position, a mean value of said first and second time differences.  
     
     
         12 . The magnetic recording and reproducing apparatus according to  claim 9 , further comprising 
 an error-rate detector for detecting a reproduction error rate in tracks being scanned by said first to fourth heads,    wherein said tracking position detector detects, as said target tracking position, said first and second time differences at a point of time when said error rate is smallest.    
     
     
         13 . The magnetic recording and reproducing apparatus according to  claim 9 , further comprising 
 an envelope-level detector for detecting a reproduced envelope level of tracks being scanned by said first to fourth heads,    wherein said tracking position detector detects, as said target tracking position, said first and second time differences at a point of time when said envelope level is largest.    
     
     
         14 . The magnetic recording and reproducing apparatus according to  claim 9 , further comprising 
 an envelope-level detector for detecting a reproduced envelope level of tracks being scanned by said first to fourth heads,    wherein said tracking position detector detects, as said target tracking position, said first and second time differences at a point of time when a lowest point of said envelope level becomes largest while said first to fourth heads scan said first to fourth tracks, respectively.    
     
     
         15 . The magnetic recording and reproducing apparatus according to one of  claims 10  to  14 , wherein said tracking position detector takes values derived by averaging said first and second time differences corresponding to said target tracking position for a predetermined number of times, for use as said first and second time differences at said target tracking position.  
     
     
         16 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including a first recording head, a second recording head, a first reproducing heard, and a second reproducing head, said first and second recording heads having azimuth angles different from each other, said first and second recording heads recording data in a track oblique to a longitudinal direction of a magnetic tape, said first reproducing head having a same azimuth angle as said first recording head, said second reproducing head having a same azimuth angle as said second recording head, said first and second reproducing heads reproducing data in said track;    a sync-signal generator for generating first and second recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first and second recording synchronizing signals to said first and second recording heads, respectively;    a sync-signal time difference detector for detecting a time difference between first and second reproduced synchronizing signals output from said first and second reproducing heads reproduced from said magnetic tape, respectively; and    a capstan-motor controller for controlling rotation of a capstan motor advancing said magnetic tape based on said time difference,    wherein said sync-signal generator outputs said first and second recording synchronizing signals substantially simultaneously, and    wherein a distance between said first and second recording heads is substantially equal to a distance between said first and second reproducing heads.    
     
     
         17 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first to fourth heads, said first and third head having same azimuth angles, said first and third heads recording data in first and third tracks oblique to a longitudinal direction of a magnetic tape, respectively, said first and third heads reproducing data in said first and third tracks, respectively, said second and fourth heads having same azimuth angles different from said azimuth angles of said first and third heads, said second and fourth heads recording data in second and fourth tracks oblique to the longitudinal direction of said magnetic tape, respectively, said second and fourth heads reproducing data in said second and fourth tracks, respectively;    a sync-signal generator for generating first to fourth recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first to fourth recording synchronizing signals to said first to fourth heads, respectively;    a sync-signal time difference detector for detecting a first time difference between reproduced synchronizing signals output from said third and fourth heads, respectively;    a track-number detector for detecting track numbers of tracks being scanned by said first to fourth heads, respectively;    a reproducing-condition detector for detecting reproducing conditions of said first to fourth heads;    an offset-time-difference detector for outputting a second time difference produced by adding or subtracting a predetermined offset value to or from said first time difference based on said reproducing conditions;    a capstan-motor controller for controlling rotation of a capstan motor based on said second time difference; and    a tracking-position detector for detecting that said first to fourth heads scan said first to fourth tracks, respectively, and for detecting and storing a center value between a maximum value and a minimum value of said first time difference in which said reproducing conditions degrade by a predetermined value.    
     
     
         18 . The magnetic recording and reproducing apparatus according to  claim 17 , 
 wherein said offset-time-difference detector does not output said second time difference when said offset time difference detector is in an offsetting operation and if said track-number detector detects a state in which at least one of said first to fourth heads is not scanning one of said first to fourth track,    wherein said offset-time-difference detector subtracts a predetermined value from said offset value when said offset value is negative, and    wherein said offset-time-difference detector adds a predetermined value to said offset value when said offset value is positive.    
     
     
         19 . The magnetic recording and reproducing apparatus according to  claim 17  or  18 , wherein said reproducing-condition detector detects said reproducing conditions according to a number of said reproduced synchronizing signals.  
     
     
         20 . The magnetic recording and reproducing apparatus according to  claim 17  or  18 , wherein said reproducing-condition detector detects said reproducing conditions based on a reproduced error rate.  
     
     
         21 . The magnetic recording and reproducing apparatus according to one of  claims 17  to  20 , wherein said offset-time-difference detector interpolates a predetermined value of error when said predetermined offset value is either at maximum or minimum of a variable range, when said reproducing conditions degrade by a predetermined degree, when said reproduced synchronizing signals are not detected, and when said first time difference is not obtained.  
     
     
         22 . The magnetic recording and reproducing apparatus according to one of  claims 17  to  21 , wherein said tracking-position detector detects a value derived by averaging said first time difference for a predetermined number of times as an initial value of said time difference corresponding to said tracking position, said first time difference being obtained by reproducing said first to fourth tracks with said first to fourth heads when said reproducing conditions are in a satisfactory condition better than a predetermined level.  
     
     
         23 . The magnetic recording and reproducing apparatus according to one of  claims 17  to  21 , wherein said tracking-position detector detects a value one-half of sum of a maximum value and a minimum value of said first time difference as an initial value of said target time difference corresponding to said target tracking position, said first time difference being obtained by reproducing said first to fourth tracks with said first to fourth heads, respectively when a rotating speed of said capstan motor is slower than a normal speed.  
     
     
         24 . The magnetic recording and reproducing apparatus according to one of  claims 17  to  23 , wherein said tracking-position detector detects a center value of mean values derived by averaging maximum values and minimum values of said first time difference for a predetermined number of times as an initial value of said target time difference corresponding to said target tracking position when said first to fourth heads are scanning said first to fourth tracks, respectively, and if said reproducing conditions degrade by a predetermined level.  
     
     
         25 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first and second heads having azimuth angles different from each other, said first and second heads recording data in first and second tracks oblique to a longitudinal direction of a magnetic tape, said first and second heads reproducing data in said first and second tracks, respectively;    a sync-signal generator for outputting first and second recording synchronizing signals to be recorded on said magnetic tape to said first and second heads, respectively;    a sync-signal time difference detector for detecting a time difference of reproduced synchronizing signals reproduced by said first and second heads, respectively;    a capstan controller for controlling rotation of a capstan motor based on said time difference;    a target-tracking-time difference detector for detecting a time difference corresponding to a target tracking position;    a first recording sync-signal delay circuit for delaying said first recording synchronizing signal to be output to said first head by a first delay time;    a second recording sync-signal delay circuit for delaying said second synchronizing signal to be output to said second recording head by a second delay time, said second delay time having an initial delay time equal to twice of said first delay time, said second delay time being adjustable at least between said first delay time and the initial delay time; and    a controller operable to 
 store a difference between first and second time differences as a reference recording divergence time, said first time difference being detected by said target-tracking-time difference detector when said magnetic recording and reproducing apparatus reproduces a reference tape recorded by a standard apparatus, said second time difference being detected by said target-tracking-time difference detector when said magnetic recording and reproducing apparatus a tape recorded by said first second heads, and  
 set said second delay time of said second recording synchronizing signal to a value given by subtracting said reference recording divergence time from said initial delay time.  
   
     
     
         26 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including a first head, a second head, a first reproducing head, and a second reproducing head, said first and second heads having azimuth angles different from each other, said first and second heads recording data in first and second tracks oblique to a longitudinal direction of a magnetic tape, said first reproducing head having a same azimuth angle as said first recording head, said first reproducing head reproducing data in said first track, said second reproducing head having a same azimuth angle as said second recording head, said second reproducing head reproducing data in said second track;    a sync-signal generator for generating first and second recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first and second recording synchronizing signals to said first and second recording heads, respectively;    a first recording sync-signal delay circuit for delaying said first recording synchronizing signal to be output to said first head by a first delay time;    a second recording sync-signal delay circuit for delaying said second recording synchronizing signal to be output to said second head by a second delay time, said second delay time having a first initial delay time equal to twice of said first delay time, said second delay time being adjustable at least between said first delay time and said first initial delay time;    a first reproduced sync-signal delay circuit for delaying a first synchronizing signal reproduced from said first reproducing head by a third delay time;    a second reproduced sync-signal delay circuit for delaying said first synchronizing signal reproduced from said first reproducing head by a fourth delay time, said fourth delay time having a second initial delay time equal to twice of said third delay time, said fourth delay time being adjustable at least up to said second initial delay time;    a sync-signal time difference detector for detecting a first time difference between signals output by said first and second reproduced sync-signal delay circuits, respectively;    a capstan controller for controlling rotation of a capstan motor during a reproducing operation based on said first time difference;    a target tracking time difference detector circuit for detecting a second time difference corresponding to a target tracking position;    a reference reproduction divergence memory for storing a time given by subtracting said second time difference during replay of a reference tape from said third delay time as a reference reproduced-time-difference divergence;    a reference-recording-divergence memory for setting said fourth delay time to a value given by subtracting said reference reproduced-time-difference divergence from said second initial delay time, and for storing, as a reference recording-time-difference divergence, a value given by subtracting, from said first delay time, said first time difference obtained when said first and second synchronizing signals are reproduced by said first and second reproducing heads when said synchronizing signals are recorded by said first and second recording heads; and    a controller for setting said second delay time to a value given by subtracting said reference recording-time-difference divergence from said first initial delay time.    
     
     
         27 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first and second heads having azimuth angles different from each other, said first and second heads recording and reproducing data in first and second tracks oblique to a longitudinal direction of a magnetic tape;    a sync-signal generator for generating first and second recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first and second recording synchronizing signals to said first and second heads, respectively;    a sync-signal time difference detector for detecting a time difference between first and second reproduced synchronizing signals reproduced by said first and second heads, respectively;    a target-tracking-time difference detector for detecting a target tracking time difference corresponding to a target tracking position;    a capstan controller for controlling rotation of a capstan motor, so that said time difference between said first and second reproduced synchronizing signals becomes equal to said target tracking time difference during a reproducing operation; and    a controller for correcting said target tracking time difference based on a time difference obtained by subtracting a time difference between first data and second data recorded on a track distanced by a predetermined distance from a time difference between said first data and said second data when reproduced.    
     
     
         28 . A magnetic recording and reproducing apparatus comprising: 
 a rotary drum including first and second heads having azimuth angles different from each other, said first and second heads recording and reproducing data in first and second tracks oblique to a longitudinal direction of a magnetic tape having a recorded portion and an unrecorded portion;    a sync-signal generator for generating first and second recording synchronizing signals to be recorded on said magnetic tape, and for outputting said first and second recording synchronizing signals to said first and second heads, respectively;    a sync-signal time difference detector for detecting a time difference between first and second reproduced synchronizing signals reproduced by said first and second heads, respectively;    a target-tracking-time-difference detector for detecting a target tracking time difference corresponding to a target tracking position;    a capstan controller for controlling rotation of a capstan motor, so that said time difference between said first and second reproduced synchronizing signals becomes equal to said target tracking time difference during reproduction;    a first recording sync-signal delay circuit for delaying said first recording synchronizing signal to be output to said first head by a first delay time;    a second recording sync-signal delay circuit for delaying said second recording delay signal to be output to said second head by a second delay time, said second delay time having an initial delay time equal to twice of said first delay time, said second delay time being adjustable at least between said first delay time and said initial delay time; and    a controller for allowing said target-tracking-time-difference detector to detect a target tracking time difference when reproducing data on said recorded portion, and for allowing said second recording sync-signal delay circuit to set said second delay time when recording data on said unrecorded portion.    
     
     
         29 . The magnetic recording and reproducing apparatus according to  claim 28 , 
 wherein said target-tracking-time-difference detector detects a first target tracking time difference corresponding to said target tracking position during reproduction of said recorded portion, and obtains a second target tracking time difference by correcting said first target tracking time difference based on a recording/reproducing time difference determined by subtracting a time interval between first data and second data recorded to be distanced by a predetermined distance in a track from a time interval between said first data and said second data when reproduced,    wherein said capstan controller controls rotation of said capstan motor, so that said time difference between said first and second reproduced synchronizing signals becomes equal to said first target tracking time difference, and    wherein said second recording sync signal delay circuit adjusts said second delay time based on said second target tracking time difference in said unrecorded portion.