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.
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0. 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.
0. 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.
0. 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.
0. 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.
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.
0. 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.
0. 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.
0. 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.
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.
2. A disk calibration and search method as set forth in
3. A disk calibration and search method as set forth in
4. A disk calibration and search method as set forth in
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
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.
7. The method as set forth in
8. The method as set forth in
9. The method as set forth in
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
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
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
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
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
15. The method as set forth in
16. The method as set forth in
17. The method as set forth in
0. 19. The method of
0. 20. The method of
0. 21. The method of
0. 22. The method 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.
0. 23. The method of
0. 24. The method 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.
0. 25. The method 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.
0. 26. The method 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.
0. 27. The method 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.
0. 28. The method 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.
0. 29. The method of
0. 32. The process of
0. 33. The process of
0. 34. The process of
0. 36. The disk drive of
0. 37. The disk drive of
0. 38. The disk drive of
0. 40. The process of
0. 41. The process of
0. 42. The process of
0. 44. The process of
0. 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.
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This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application entitled Disk Calibration Method In CD-ROM Drive System earlier filed in the Korean Industrial Property Office on 13 May 1995, and there duly assigned Serial No. 95-11815 by that Office.
The present invention relates to a disk drive such as a compact disk, and more particularly, to a disk calibration and search method for a compact disk read only memory (i.e., a CD-ROM) disk drive, for increasing the setting accuracy of the number of disk tracks when a pickup searches the disk tracks in the disk drive.
As currently manufactured in commercial quantities, a compact disk is a small disk with, for example, a twelve centimeter outer diameter, on which a plurality of concentric or spiral tracks are formed along one side of the disk. These tracks comprise a multitude of fine grooves whose size corresponds to several micrometers are formed, and represent predetermined digitalized signals such as audio information signals and computer information signals. Each groove is called a pit and the space between the pits are called islands or lands. Generally, the tracks are spirally arranged from the center of the disk and the interval between the tracks is known as a pitch, and this interval or pitch is generally 1.6 μm.
When driving a sled motor for transferring a pickup of the compact disk drive radially across 14 41 counts, step 54, the number of pulses generated from frequency generator 12 in accordance with the rotation of sled motor 11. Here, the track number can be counted by counting the pulse number. It should be noted, however, that the counting operation is delayed for a predetermined period (e.g., 500 μsec), in order to stabilize the pickup 14 after the initial jump in step 52. Also, since the pulse is counted on the basis of the edge of the pulse, it is checked, step 55, a check is made during step 55 to determine whether the starting point of the pulse counting is the edge of the pulse, prior to the actual counting of the number of pulses generated from the frequency generator 12. When the starting point of the pulse counting is not the edge of the pulse, the counter existing in the microprocessor 41 continuously checks whether the starting point is the edge of the pulse. When the starting point is the edge of the pulse, it is checked whether a track is detected by pickup 14, step 56. When a track is not detected by pickup 14, microprocessor 41 continuously checks pickup 14 for the detection of a track.
For each track detected by pickup 14, a counter accumulatively sums the number of the tracks detected, step 57. Thereafter, it is checked a check is made to determine whether the pulse number counted by the counter of the microprocessor 41 is equal to or greater than 160, step 58. Here, the number 160 was determined based on the data which is obtained through 8 full rotations of the disk during all experimental procedures using the CD-ROM drive system designed so that frequency generator 12 generates 20 pulses per one rotation of the disk. If the pulse number is not equal to or greater than 160 in step 58, the processes are repeated from step 56. Otherwise, when the pulse number is equal to or greater than 160, a frequency generator track number (Z) is calculated by diving dividing the summed track number by 160, step 59,, ie., microprocessor 41 calculates a unit track number of the disk per a single movement of pickup 14, that is, the number of tracks the pickup moves per pulse generated by the frequency generator. The calculated track number (Z) is stored (set) in program memory 43, step 60, and the process returns to a root program in microprocessor 41 in order to perform another rotation. Microprocessor 41 also calculates an average pitch between the tracks in accordance with the calculated unit track number.
Through the above chain of steps, the initial disk calibration operation is completed. Then, on the basis of the track number (Z) stored in the program memory 43, a number of tracks to be jumped by the pickup 14 for performing a search operation is converted into a pulse number to be generated by frequency generator 12 during program performance.
Referring now to
Next, the current location of pickup 14 on disk 16 is read out and the distance from the read out current position to the target track is calculated, step 62. After the distance calculation, a number of tracks (X) to be jumped by pickup 14 is calculated, step 63, and then it is determined whether a long jump is required or not, step 64. The determination of whether a long jump is required is based on the number of tracks (X) to be jumped. If the long jump is not required, pickup 14 performs a short jump, step 65. A short jump is a jump of a predetermined number of tracks. Then, it is checked in step 66 whether the intended target track was reached by the short jump. If the short jump does not reach to the target track, a value, such as one, is added to the initial track number to the target track, i.e., the initial value of the number of tracks (X) to be jumped, step 66, and then the process returns to the step 62. If the short jump reaches the target track, the process returns to the root program in microprocessor 41.
On the other hand, if it is determined in the step 64 that the long search (i.e., a “long jump”) is required, a check is made to determine whether the track number to the target track is equal to a value obtained by adding one to the initial value of the number of tracks (X) to be jumped, step 68. If the track number is not equal to the value obtained by adding one to the initial value, the track number of tracks (X) to be jumped by the pickup is divided by the initial unit track number to for the traget target track, step 69 to obtain a value (Y). Then, in step 70, the sled motor 11 is rotated in accordance with a pulse number converted from the value (Y) obtained in the step 69, and then the process proceeds to step 66 discussed above.
On the other hand, when it is determined in step 68 that the track number to the target track is equal to the value obtained by adding one to the initial value, a second subroutine for adjusting the track number is performed, step 71, and then the process proceeds to step 69 discussed above. Here, this second subroutine for adjusting the track number is for compensating for a search error generated during the search subroutine performance due to a defect of the disk.
The process of this second subroutine for adjusting the track number will be described with reference to FIG. 7. First, the current jumping direction and the previous jumping direction are compared (step 81). Then, it is checked whether the current jumping direction is the same as the previous jumping direction (step 82). If the current jumping direction is the same as the previous jumping direction, a value (U) is obtained by dividing the track number (X) to be jumped by the pickup 14 by 100. Here, the numerals “100” is arbitrarily set for the convenience of calibration with regard of 300˜400 error tracks. The value (U) is added to a value (P) obtained by accumulatively summing the values (U) to set a new value (P) (step 83). Then, it is determined that whether the newly set value (P) is over 100 (step 84). If the newly set value (P) is over 100, a value obtained by adding one to the frequency generator track number (Z) is set as a new frequency generator track number (Z) and the value (P) is set as zero. This adjusted frequency generator track number is stored in the microprocessor 41. Otherwise, if it is determined in the step 84 that the value (P) is not over 100, the process returns to the root program.
On the other hand, if it is determined in the step 82 that the current jumping direction is not equal to the previous jumping direction, a value (U) is obtained by dividing the track number (X) to be jumped by the pickup 14 by 100 and the value (U) is subtracted from value (P) to set a new value (P) (step 86). Then, it is determined whether the newly set value (P) is below zero (step 87). If the newly set value (P) is not below zero, the process returns to the root program. Otherwise, if the newly set value (P) is below zero, a value obtained by subtracting one from the frequency generator track number (Z) is set as a new frequency generator track number (Z) and the value (P) is set as 100 (step 88).
As described above, in the disk calibration method in the disk drive according to the present invention, the track number of each disk inserted into the disk drive is adjusted at the initial state in accordance with the number of pulses generated from the frequency generator, thereby improving accuracy in the disk calibration. Also, the error generated during the searching operation of the pickup is compensated through a simple process. Furthermore, since less internal memory is used for performing the above calibration process, the memory efficiency is increased.
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