Abstract:
A technique for measuring a position error signal of a disk drive, includes measuring the width of a track by sequentially following two adjacent tracks upon turning on power, and updating a percentage of the position error signal according to the measurement of the track width.

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for METHOD OF MEASURING THE POSITION ERROR SIGNAL OF A DISK DRIVE earlier filed in the Korean Industrial Property Office on the 5 th  day of June 1996 and there duly assigned Ser. No. 20051/1996, a copy of which application is annexed hereto. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention concerns a disk drive, and more particularly to a technique for measuring the position error signal of a disk drive. 
     2. Description of the Related Art 
     Generally a position error signal (hereinafter referred to as a “PES”) obtained by detecting a burst is valued by the resolution of an A-D converter, including the maximum and minimum values. Therefore, the percentages of PES are not determined by the width of the track, but are determined by an absolute value (constant) peculiar to the resolution of an A-D converter. Normally the width of the track may vary with the head margin, characteristics of the recording margin, servo write, etc., so that the correctness of the percentages of PES may not be secured if the width of the track varies with the apparatus, circuits or external environment. 
     The following patents each disclose features in common with the present invention but do not teach or suggest the specifically recited technique for measuring the position error signal of a disk drive in accordance with the present invention: U.S. Pat. No. 5,576,906 to Fisher et aL, entitled Synchronous Detection Of Concurrent Servo Bursts For Fine Head Position In Disk Drive, U.S. Pat. No. 5,576,910 to Romano et al., entitled Burst Comparison And Sequential Technique For Determining Servo Control In A Mass Storage Disk Device, U.S. Pat. No. 5,602,692 to Freitas et al., entitled Sampled Position Error Signal Demodulation System For Banded Data Disk Drives, U.S. Pat. No. 5,602,693 to Brunnett et al., entitled Method And Apparatus For Sensing Position In A Disk Drive, U.S. Pat. No. 5,615,058 to Chainer et aL, entitled Method And System For Writing A Servo-Pattern On A Storage Medium, U.S. Pat. No. 5,453,887 to Negishi et al., entitled Head Tracking Servo Pattern, and U.S. Pat. No. 5,381,281 to Shrinkle et al., entitled Disk Drive System Using Multiple Embedded Quadrature Servo Fields. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a technique for measuring a position error signal of a disk drive. 
     It is another object of the present invention to provide a technique for measuring the correct percentage of the position error signal of a disk drive by measuring the track width upon turning on power. 
     According to the present invention, a technique for measuring a position error signal of a disk drive, comprises measuring the width of a track by sequentially following two adjacent tracks upon turning on power, and updating a percentage of the position error signal according to the measurement of the track width. 
     The present invention will now be described more specifically with reference to the drawings attached only by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is a block diagram of a hard disk drive according to the present invention; 
     FIG. 2 is a graph for illustrating letters ‘N’ and ‘Q’ expressed by measuring a track width in measuring power-on operation; and 
     FIGS.  3 A- 3 B together form a flowchart of control according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a plurality of disks  10  are rotated by a spindle motor  34 . A plurality of heads  12  are respectively located on a plurality of disks and are installed on a plurality of support arms extended from a E-block assembly  14  assembled with a rotary voice coil actuator  30  to the disk. A pre-amplifier  16  supplies an analog read signal to a read/write channel circuit  18  by pre-amplifying a signal picked up by one of the heads  12  during reading, and lets a corresponding one of the heads  12  write on a disk by supplying coded write data output from the read/write channel circuit  18 . The read/write channel circuit  18  detects and decodes a data pulse from a read signal output by the pre-amplifier  16  and supplies it to a disk data controller(hereinafter referred to as a ‘DDC’)  20 , and supplies write data from the DDC  20  to the pre-amplifier  16  by decoding. 
     The DDC  20  writes data output from a host computer on a disk through the read/write channel circuit  18  and the pre-amplifier  16 , and transmits data to the host computer by reading it from a disk. The DDC  20  interfaces a communication between the host computer and a microcontroller  24 . A buffer RAM  22  temporarily stores data transmitted between the host computer, the microcontroller  24  and the read/write channel circuit  18 . A microcontroller  24  controls a track detection and follow-up responding to an order of read or write received from the host computer. A ROM  26  stores a performance program of the microcontroller  24  and all sorts of command values. Servo driver  28  supplies a driving current to a voice coil of the actuator  30 . The actuator  30  moves the head  12  on the disk  10  according to the level and direction of the driving current. A spindle motor driver  32  rotates the disk  10  according to a control value generated by the microcontroller  24 . A disk signal controller  36  supplies a PES output from the read/write channel circuit  18  to the microcontroller  24  by converting it into a digital signal. 
     Referring to FIG. 2, in two adjacent tracks, an n−1 track (odd number) and an n track (even number), there exists an A burst, B burst, C burst and D burst for generating a PES. An A burst exists in the outside, being one half of each n−1 track and n track. A B burst exists in the inside, being one half of each n−1 track and n track. A C burst exists only in the n−1 track, and a D burst exists only in the n track. According to the present invention, FIG. 2 illustrates N and Q defined as follows: 
     
       
         N=A−B 
       
     
     
       
         Q=C−D 
       
     
     wherein A, B, C and D represent burst signals. 
     FIG. 2 illustrates each value of the n−1 track and n track in each part of the n−1 track and n btrack. N equals 0 (zero) in a center line  42  of the n−1 track and Q equals D in a center line  40  of the n track. Referring to FIGS. 1,  2  and  3 A- 3 B, the microcontroller  24  checks to determine if there is a power on in step  100  and performs a track width measuring routine in step  102 . Accordingly, the microcontroller  24  lets the head  12  seek a first track ‘n’ by servo-control in step  104  and thereafter confirms whether or not the seek has been completed by a servo signal read from the disk  10  in step  106 . If the seek has been completed, the microcontroller  24  waits for a fixed time for securing an accuracy of track width measuring and detection stabilization in step  108 . In step  110 , the microcontroller  24  sets a condition for measuring a track width and controls the head to move according to the condition ‘N=Q’. 
     Referring to FIG. 2, the head  12  remains near the center line  40  of the first track ‘n’ before step  110 . The head  12  moves to the line  44  for track-following (hereinafter referred to as a ‘track-following line’) when a track width measuring condition is set at N=Q in step  110 . The track-following line  44  is positioned in a center between a center line  40  of track n and a line  48  adjacent to track n−1 and parallel to each other. The track-following line  44  is positioned at the value of N=Q. The microcontroller  24  follows the ‘n’ track along the track-following line when the head  12  is positioned at the track-following line  44  in step  110  and confirms the completion of track-following in step  113 . Upon completion of track-following, it calculates the ‘n’ value and stores it in step  114 . When N is equal to A−B contours the track-following line  44 , A is not detected and only half of the B value is detected. Accordingly, the N value is B/2. In step  116 , the microcontroller  24  lets the head  12  seek a second track by servo-control. The operations from steps  118  to  126  are similar to that from steps  106  to  114 . In steps  118  to  126 , the N value is calculated by following a track-following line  46  of an n−1 track. When N is equal to A−B contours a track-following line  46 , B is not detected and only half of the A value is detected. Accordingly, the N value is A/2. 
     After performing steps  106  to  114  and  118  to  126 , the microcontroller  24  calculate a track width by adding the N value of track n to that of track n−1 in step  130 . Accordingly, the track width equals A+B/2. Thereafter, the microcontroller  24  updates a percentage value of PES by measuring a track width in step  132 . Accordingly the present invention measures a percentage value of PES by measuring a track width in measuring power-on operation, resulting in measuring a PES. 
     It should be understood that the present invention is not limited to the particular embodiment disclosed herein as the best mode contemplated for carrying out the present invention, but rather that the present invention is not limited to the specific embodiments described in this specification except as defined in the appended claims.