Disk calibration and search method in a cd-rom drive system

Abstract

A disk calibration and search method in a disk drive is provided, in which, after an initialization step, a pickup is jumped to a first position and moved radially in a predetermined direction in response to pulses generated by a frequency generator. During this radial movement the number of tracks crossed are is counted. The counting is continued until a predetermined number of the pulses generated by the frequency generator have been generated. A calculated frequency generator track number is then obtained by dividing the counted number of tracks by the predetermined number of pulses generated by the frequency generator, i.e., calculating a unit track number of the disk per a single movement of the pickup, that is, the number of tracks the pickup moves per pulse generated by the frequency generator. The calculated frequency generator track number is stored in memory used to control the frequency generator for jumping the pickup during a search for a target track. An average pitch between the tracks is calculated in accordance with the calculated unit track number; and a moving amount for a drive to jump the pickup from a current position to a target track is then determined. The calibration and search methods will be described in greater detail below.

1. A disk calibration and search method in a disk drive, comprising the steps of:
 positioning a data reading pickup across to a first position on a disk;  
 jumping said pickup in a predetermined direction across tracks on said disk;  
 counting the number of tracks detected during said jumping step;  
 calculating a unit track number of the disk per a single movement of a driving means for jumping the pickup and calculating an average pitch between the tracks in accordance with the calculated unit track number; and  
 determining a moving amount for controlling the driving means to jump the pickup from a current position to a target track.  
 
     
     
       2. A disk calibration and search method as set forth in  claim 1 , further comprising a step of delaying said step of counting for a predetermined initial period to stabilize said pickup. 
     
     
       3. A disk calibration and search method as set forth in  claim 1 , further comprising a step of performing a searching operation by jumping the pickup from the current position to the target track. 
     
     
       4. A disk calibration and search method as set forth in  claim 3 , said step of performing the searching operation comprises the steps of:
 jumping said pickup to a target track to check the track number to the target track, thereby initializing the track number with the checked track number to obtain an initial value;  
 reading out the current location of the pickup on the disk and calculating a number of tracks (X) necessary to jump said pickup from said current position and said target track;  
 determining, on the basis of said number of tracks (X), whether a long jump is required to move said pickup to said target track;  
 performing a short jump for moving said pickup towards said target track when it is determined that said long jump is not required;  
 determining whether said pickup reached said target track after said short jump;  
 adjusting said initial value by adding one to said initial and returning the process to said step reading out the current location of said pickup when said pickup does not reach said target track after said short jump;  
 checking whether the number of tracks (X) to the target track is equal to a value obtained by adding one to the initial value when said long jump is required;  
 dividing said number of tracks (X) to be jumped by the pickup by said initial value, when said number of tracks (X) to the target track is not equal to a value obtained by adding one to said initial value;  
 moving the driving means of the pickup on the basis of a value obtained by said dividing step; and  
 re-adjusting the track number by regulating said average pitch when said number of tracks (X) to the target track is equal to a value obtained by adding one to the initial value.  
 
     
     
       5. A disk calibration and search method as set forth in  claim 4 , said re-adjusting step comprising the steps of:
 determining whether a current jumping direction of said pickup is equal to a previous jumping direction of said pickup;  
 dividing the number of tracks (X) to be jumped by the pickup by a reference value and adding the obtained value to a previously accumulated value to provide a first accumulated value when it is determined that the current jumping direction is equal to said previous jumping direction;  
 determining whether said first accumulated value is greater than said reference value;  
 adjusting said unit track number by adding a predetermined value to said unit track number when said first accumulated value is greater than said reference value and resetting said first accumulated value to zero;  
 dividing said number of tracks (X) to be jumped by the pickup by said reference value and subtracting the obtained value from the previously accumulated value to provide a second accumulated value said current jumping direction is not equal to said previous jumping direction;  
 determining whether said second accumulated value is less than zero; and  
 adjusting said unit track number by subtracting said predetermined value from said unit track number when said second accumulated value is less than zero.  
 
     
     
       6. A disk calibration and search method for a disk drive having a disk mounted therein, a frequency generator for generating a pulse used to detect an amount of rotation of a sled motor installed at an end of a shaft of a sled motor, an optical sensor installed adjacent said frequency generator for detecting rotation of said frequency generator, a pickup for reading data and detecting tracks on said disk, said disk being rotated by a spindle motor, drive means for moving said pickup, a microprocessor for controlling said disk drive, a short-jump controller for controlling a short jump of said pickup in accordance with a short jump control command from said microprocessor, and a program memory for storing various data used for reproducing information from said disk, said method comprising steps of:
 jumping said pickup to a first position on said disk;  
 jumping said pickup from said first position towards a second position on said disk;  
 counting tracks detected by said pickup when jumping towards said second position;  
 counting pulses generated by said frequency generating means while jumping said pickup towards said second direction to obtain a summed track number;  
 stopping said step of counting tracks when said step of counting pulses counts a predetermined number of pulses;  
 dividing said summed track number by said predetermined number of pulses to obtain a frequency generator track number;  
 storing said frequency generator track number in said program memory; and  
 searching for a target track on the basis of said stored frequency generator track number.  
 
     
     
       7. The method as set forth in  claim 6 , further comprising a step of delaying said step of counting pulses by a predetermined delay period. 
     
     
       8. The method as set forth in  claim 6 , further comprising a step of starting said step of counting pulses when an edge of said pulse is detected. 
     
     
       9. The method as set forth in  claim 6 , said step of searching for a target track comprising steps of:
 generating an initial value representing an initial number of tracks to said target track;  
 reading out a current position of said pickup;  
 calculating a distance from said current position to said target track;  
 determine a number of tracks to be jumped by said pickup to move said pickup to said target track in response to said calculated distance;  
 determining whether a long jump jump is required to move said pickup to said target track;  
 determining whether said number of tracks to be jumped to said target track is equal to a predetermined value added to said initial value;  
 dividing said number of tracks to be jumped by said initial value when said number of tracks to be jumped to said target track is not equal to said predetermined value added to said initial value;  
 converting the result obtained by said dividing step to a pulse number;  
 rotating said sled motor in response with said pulse number.  
 
     
     
       10. The method as set forth in  claim 9 , further comprising steps of
 controlling said short-jump controller to jump said pickup a short jump towards said target track when said long jump is not required;  
 determine whether said pickup has reached said target track after said rotating step and after said controlling step;  
 adding said predetermined value to said initial track number and returning to said step of reading out a current position of said pickup when it is determined that said pickup has not reached said target track; and  
 returning to a root program of said microprocessor when said pickup has reached said target track.  
 
     
     
       11. The method as set forth in  claim 9 , further comprising a step of:
 adjusting said number of tracks to said target track when said number of tracks to be jumped to said target track is equal to said predetermined value added to said initial value.  
 
     
     
       12. The method as set forth in  claim 11 , said adjusting step comprising steps of:
 comparing a current jumping direction with a just previous jumping direction;  
 determining whether said current jumping direction is the same as said just previous jumping direction;  
 dividing said number of tracks to be jumped by a reference value and adding the obtained value to a previously accumulated value to provide a first accumulated value when it is determined that the current jumping direction is the same as said just previous jumping direction;  
 determining whether said first accumulated value is greater than said reference value; and  
 adjusting said number of tracks to said target track by adding said predetermined value to said number of tracks to said target track when said first accumulated value is greater than said reference value and resetting said first accumulated value to zero.  
 
     
     
       13. The method as set forth in  claim 12 , further comprising steps of:
 dividing said number of tracks to said target track to be jumped by the pickup by said reference value and subtracting the obtained value from the previously accumulated value to provide a second accumulated value when said current jumping direction is not the same as said just previous jumping direction;  
 determining whether said second accumulated value is less than zero; and  
 adjusting said number of tracks to said target track by subtracting said predetermined value from said number of tracks to said target track when said second accumulated value is less than zero.  
 
     
     
       14. The method as set forth in  claim 6 , said step of jumping said pickup to a first position comprises jumping said pickup to an inner circumference of said disk. 
     
     
       15. The method as set forth in  claim 14 , said step of jumping said pickup towards said second position comprises jumping said pickup to an outer circumference of said disk. 
     
     
       16. The method as set forth in  claim 6 , said first position comprising a lead in area of said disk, said second position comprising a lead out are of said disk. 
     
     
       17. The method as set forth in  claim 8 , further comprising a step of determining when said pickup detects a track when said edge of said pulse is detected. 
     
     
       18. A method in a disk drive, comprising the steps of:
   activating a motor moving a data reading pickup from a first track to a second track for a period of time;        counting a first number of tracks during moving of said data reading pickup; and        determining a unit track number by dividing said number of tracks by said period of time.      
     
     
       19. The method of  claim 18 , wherein said unit track number represents a track pitch.  
     
     
       20. The method of  claim 18 , wherein said unit track number represents an average track pitch of said tracks.  
     
     
       21. The method of  claim 18 , further comprising the step of storing said unit track number in a memory.  
     
     
       22. The method of  claim 18 , further comprising the steps of:
   detecting the number of pulses generated from said motor, the number of pulses representing said period of time; and        determining said unit tract number by dividing said first number of tracks by said number of pulses.      
     
     
       23. The method of  claim 22 , wherein said unit track number represents an average track of said tracks.  
     
     
       24. The method of  claim 22 , further comprising the steps of:
   rotating a disk while said data reading pickup is moving;        providing said motor moving said data reading pickup in a rate of a predetermined distance per each rotation of said disk during said period of time; and        generating said number of pulses in response to all of each predetermined distance.      
     
     
       25. The method of  claim 22 , further comprising the steps of:
   rotating a disk while said data reading pickup is moving; and        detecting said number of pulses generated from said motor in response to movement of said data read pickup, said number of pulses representing the number of rotation of said disk.      
     
     
       26. The method of  claim 22 , further comprising the steps of:
   determining a second number of tracks between a current track and a target track;        determining a second number of pulses by dividing said first amount by said unit track number; and        activating said motor to move said data reading pickup in accordance with said second number of pulses.      
     
     
       27. The method of  claim 22 , further comprising the steps of:
   storing said unit track number in a memory;        determining a second number of tracks between a current track and a target track;        determining a second number of pulses by dividing said first amount by said unit track number; and        activating said motor to move said data reading pickup in accordance with said second number of pulses.      
     
     
       28. The method of  claim 22 , further comprising the steps of:
   storing said unit track number in a memory;        determining a second number of tracks between a current track and a target track;        determining a second unit track number in dependence upon said first number of tracks and said second number of tracks        determining a second number of pulses by dividing said second number of tracks by said second unit track number; and        activating said motor to move said data reading pickup in accordance with said second number of pulses.      
     
     
       29. The method of  claim 22 , further comprising of the step of storing said second track number in said memory.  
     
     
       30. A disk calibration and search method in a disk drive, comprising the steps of:
   positioning a data reading pickup across to a first position on a disk;        jumping said pickup in a predetermined direction across tracks on said disk;        counting the number of tracks detected during said jumping step;        calculating a unit track number of the disk per a single movement of a driving means for jumping the pickup; and        determining a moving amount for controlling the driving means to jump the pickup from a current position to a target track.      
     
     
       31. A disk calibration and search process, comprising:
   making a count of a number of tracks crossed when a pickup is jumped to a first position and moved radially from said first position during generation of a selected number of pulses;        determining an unit track number in dependence upon a relation between said count and said selected number;        determining an average pitch between said tracks in dependence upon said unit track number; and        determining a moving amount to shift the pickup between a current position on the disk and a target track, in dependence upon said average pitch.      
     
     
       32. The process of  claim 31 , making said count while moving said pickup from a track on one extremity of the disk to a track on a radially opposite extremity of the disk.  
     
     
       33. The process of  claim 31 , with said first position comprised of an innermost track of said disk, and with said count made while said pickup is moved radially from said innermost track to an outermost track of said disk.  
     
     
       34. The process of  claim 31 , comprised of initiating said count after detecting an edge of said pulses.  
     
     
       35. A disk drive, comprising:
   a motor;        a pickup oriented to make a count of a number of tracks on a memory disk crossed when said motor jumps said pickup to a first position on the disk and moves said pickup radially from said first position in response to application of a selected number of pulses to said motor; and        a controller determining an unit track number in dependence upon a relation between said count and said selected number, determining an average pitch between said tracks in dependence upon said unit track number, and determining a moving amount to shift the pickup between a current position on the disk and a target track, in dependence upon said average pitch.      
     
     
       36. The disk drive of  claim 35 , comprised of said controller making said count while said motor moves said pickup from a track on one extremity of the disk to a track on a radially opposite extremity of the disk.  
     
     
       37. The disk drive of  claim 35 , with said first position comprised of an innermost track of said disk, and with said controller making said count while said pickup is moving radially from said innermost track to an outermost track of said disk.  
     
     
       38. The disk drive of  claim 35 , comprised of said controller initiating said count after detecting an edge of said pulses.  
     
     
       39. A disk drive manufacturing process, comprising:
   selecting a motor;        mounting a pickup oriented to make a count of a number of tracks on a memory disk crossed when said motor jumps said pickup to a first position on the disk and moves said pickup radially from said first position in response to application of a selected number of pulses to said motor; and        making an operational connection between a controller and said motor and said pickup, with said connection enabling said controller to determine a unit track number in dependence upon a relation between said count and said selected number, determine an average pitch between said tracks in dependence upon said unit track number, and determine a moving amount to shift the pickup between a current position on the disk and a target track, in dependence upon said average pitch.      
     
     
       40. The process of  claim 39 , comprised of said controller making said count while said motor moves said pickup from a track on one extremity of the disk to a track on a radially opposite extremity of the disk.  
     
     
       41. The process of  claim 39 , with controller designating said first position comprised of an innermost track of said disk, and with said controller making said count while said pickup is moving radially from said innermost track to an outermost track of said disk.  
     
     
       42. The process of  claim 39 , comprised of said controller initiating said count after detecting an edge of said pulses.  
     
     
       43. A disk calibration and search process, comprising:
   moving a pickup radially from a track on one extremity of the disk to a track on a radially opposite extremity of the disk;        beginning a count of pulses with an edge of a plurality of pulses generated during said movement;        making a count of a number of tracks crossed during said movement; and        determining a track number in dependence upon a relation between said count of said number of said count of pulses.      
     
     
       44. The process of  claim 43 , with said one extremity comprised of an innermost track of said disk, and with said count of said number being made while said pickup is moved radially from said innermost track to an outermost track of said disk.  
     
     
       45. A disk calibration and search process, comprising:
   moving a pickup to a location on the disk and reading from said disk a current position of the pickup on the disk while said pickup is at said location;        establishing an initialized value by determining a number of tracks lying between said location and a designation of a target track;        characterizing relatively of a movement of said pickup from said location to said target track as one of a longer jump and shorter jump;        when said movement is characterized as a shorter jump, moving said pickup in conformance to said shorter jump and making a determination of whether said pickup has reached said target track;        when said movement is characterized as a longer jump, establishing an adjusted value when said target track corresponds to an addition of one to said initialized value, and after moving said pickup in correspondence to a pulse value obtained by dividing said number of tracks by said adjusted value, making said determination of whether said pickup has reached said target track;        when said movement is characterized as a longer jump and said target track does not correspond to said addition, and after moving said pickup in correspondence to a pulse value obtained by dividing said number of tracks by said initialized value, making said determination of whether said pickup has reached said target track; and        establishing said initialized value again when said determination indicates that said pickup has not reached said target track after said moving of said pickup.      
     
     
       46. The process of again establishing said initialized value as set forth in  45 , comprised of:
   adding one to said designation of said target track;        reading from said disk a current position of the pickup on the disk; and        setting said initialized value to indicate a number of tracks lying between said current position and said designation of said target track.