公开(公告)号：MY107468A

公开(公告)日：1995-12-31

申请号：MYPI19911799

申请日：1991-09-19

Applicant: IBM

Inventor： ALAN AUGUST FENNEMA ,  ROBERT ALAN KLEM

IPC: G11B7/00 ,  G11B7/09 ,  G11B7/095

Abstract: A FOCUS ACQUISITION SYSTEM (46-49, 56-58, 65-66, 70-76) INCLUDES PROVIDING A FOCUS OFFSET AND CHANGING THE OFFSET SYMMETRICALLY FOR EACH MEASUREMENT CYCLE. THE AMPLITUDES OF THE READBACK OR TRACKING ERROR SIGNAL ARE SENSED AND COMPARED. WHEN THE AMPLITUDES OF THE TRACKING ERROR OR READBACK SIGNAL IS DIFFERENT AT EACH OF THE OFFSETS, THEN A NEW MEASURMENT CYCLE IS PERFORMED AFTER CALCULATING A NEW OFFSET VALUE. THE PROCESS IS REPEATED UNTIL THE TEMPORARY MEASUREMENT OFFSETS RESULT IN READBACK AMPLITUDES THAT ARE SUBSTANTIALLY EQUAL. A BEST FOCUS IS THEN INDICATED AS BEING A POSITION IN WHICH SMALL DEFOCUSSING WILL NOT SUBSTANTIALLY DEGRADE THE QUALITY OF THE READBACK SIGNAL.

公开(公告)号：MY107893A

公开(公告)日：1996-06-29

申请号：MYPI19911711

申请日：1991-09-19

Applicant: IBM

Inventor： ALAN AUGUST FENNEMA

IPC: G11B17/22 ,  G11B7/00 ,  G11B7/085 ,  G11B7/09 ,  G11B7/095

Abstract: A SERVO POSITIONING SYSTEM, SUCH AS USED IN AN OPTICAL DISK OR OTHEER TYPES OF DISK DRIVES INCLUDES FOCUS AND POSITIONING SERVO CIRCUITS. WHEN A FOCUS ERROR IS DETECTED, THEN IT IS DESIRED TO STOP THE OPERATION OF THE POSITIONING SYSTEM. SIMILARLY, WHEN A POSITIONING ERROR IS DETECTED, SUCH AS EXCESSIVE SPEED OR A NON-ZERO VELOCITY AT THE END OF A SEEK OR POSITIONING MOTION, THE HEAD CARRIAGE SHOULD ALSO BE STOPPED. THE STOPPING OF THE HEAD CARRIAGE IS BY DYNAMIC BRAKING THROUGH USE OF A POWER AMPLIFIER WHICH IS SWITCHED FROM A TRANSCONDUCTANCE MODE USED DURING NORMAL SERVO POSITIONING OPERATIONS TO A VOLTAGE AMPLIFYING MODE WHICH IS SET TO A ZERO INPUT FOR DYNAMICALLY BRAKING THE SERVO POSITIONING SYSTEM TO A SAFE SPEED AND THENCE TO A STOP CONDITION WHEREUPON FURTHER ERROR RECOVERY PROCEDURES MAYBE EMPLOYED.(FIG. 1)

公开(公告)号：MY105387A

公开(公告)日：1994-09-30

申请号：MYPI19910753

申请日：1991-05-03

Applicant: IBM

Inventor： DAVID PAUL MCREYNOLDS ,  ALAN AUGUST FENNEMA ,  EDWIN RALPH CHILDERS

IPC: G02B7/02 ,  G11B7/08 ,  G11B5/596 ,  G11B7/09 ,  G11B21/00 ,  G11B33/08

Abstract: AN OPTICAL DISK RECORDER, OR OTHER APPARATUS, USE A ROTARY ACTUATOR FOR SUPPORTING A WORK TOOL, SUCH AS AN OBJECTIVE LENS WHICH IS PIVOTABLE OR ROTATABLE ABOUT A PIVOT PIN. ROTATION CAUSING OR TRACKING COILS ON THE ROTARY ACTUATOR ARE DISPOSED ADJACENT TO PERMANENT MAGNET TO SELECTIVELY EFFECT ROTATION OF THE ROTARY ACTUATOR ABOUT THE PIVOT PIN. A BIAS ELECTRICAL CURRENT IS SUPPLIED TO THESE COILS TO GENERATE MAGNETIC FIELDS WHICH ARE IN OPPOSITE ROTATIONAL SENSES; SUCH FIELDS FORCE THE ROTARY ACTUATOR AGAINST THE PIN IN SUCH A MANNER THAT THE POINT OF CONTACT BETWEEN THE ROTARY ACTUATOR AND THE PIN FOLLOWS THE ROTATION OF THE ACTUATOR ABOUT THE PIN. (FIG. 2)