Kechen C Cheng

US Patent:

6747925, Jun 8, 2004

Filed:

Nov 28, 2001

Appl. No.:

09/996258

Inventors:

Kechen Cheng - Palo Alto CA

Assignee:

ProMOS Technologies Inc. - Hsin-Chu

International Classification:

G11B 700

US Classification:

369 4435, 369 5338

Abstract:

A method for generating a center error signal in an optical storage system, as well as an optical storage system, is disclosed. Through the use of the method and system in accordance with the present invention, a decrease in manufacturing costs is achieved since very precise and expensive mirrors and/or photo detectors are not needed. A first embodiment of the invention includes a method for generating a center error signal in an optical storage system, the optical storage system comprising a tracking coil and an optical pick up unit, the optical pick up unit including a light beam. The method comprises the steps of sensing a voltage by a tracking coil, providing the voltage to a center error generation circuit, generating a center error signal from the center error generation circuit based on the voltage and utilizing the center error signal to center the light beam. A second embodiment of the invention includes an optical storage system. The optical storage system comprises an optical pick up unit, the optical pick up unit including a light beam, a tracking coil coupled to the optical pick up unit, the tracking coil comprising means for sensing a voltage, a center error generation circuit coupled to the tracking coil, means for providing the voltage to the center error generation circuit wherein a center error signal is generated based on the voltage; and means for utilizing the center error signal to center the light beam.

US Patent:

20030061000, Mar 27, 2003

Filed:

Sep 27, 2001

Appl. No.:

09/965956

Inventors:

Kechen Cheng - Palo Alto CA, US
David Chen - San Jose CA, US

International Classification:

G06F015/00

US Classification:

702/150000

Abstract:

A method and system for searching in a track in an optical storage system is disclosed. The optical storage system includes an optical pick up unit (OPU) coupled to a carriage. The method and system comprises receiving a command to indicate that the OPU is to move to a target position of the track. The method and system includes providing first and second output signals, each of the output signals having a rising edge and a falling edge. The rising and falling edges indicate movement of the carriage. The method and system further includes counting each of the rising edges and the falling edges of each of the first and second output signals and providing a sensor count for each of the rising and falling edges; a plurality of sensor counts are provided by movement of the carriage. The method and system finally includes utilizing the plurality of sensor counts to determine the distance the carriage has moved and moving the OPU to the target position based upon the plurality of sensor counts. The spindle speed at each sledge count location can be pre-calculated and stored in the look-up table, and the CLV spindle speed at target radius can be adjusted on the fly and hence reduce the seek time. By using the sledge sensor counts, the surface of the optical disk can be divided into several zones. The spindle speed can be defined and read from a look-up table for zone CAV control scheme. By dividing the disk surfaces into several zones, whenever any seek error happens during the seek operation the system processor can issue the command to re-seek to the target location rapidly without doing the recal procedure.

US Patent:

47243708, Feb 9, 1988

Filed:

Oct 14, 1986

Appl. No.:

6/918501

Inventors:

Alex Moraru - Fremont CA
Kechen Cheng - Sunnyvale CA

Assignee:

Konishiroku Photo Industries Co., Ltd. - Tokyo

International Classification:

G05B 1300

US Classification:

318561

Abstract:

A servo system intermittently samples servo sectors from a data disk to obtain the position of the read/write head and to maintain an on-track alignment. A glass scale measures the movement of the transducer head and provides a velocity signal. An integrator integrates the velocity signal to produce a fill-in position signal. This fill-in position signal is added to the position signal from the last sampled servo sector to provide a position compensator with position information when the head is in between servo sectors. An on-track detector circuit and a damping circuit heavily damp movement of the transducer head when the head is in the on-track position. A gain circuit modifies the signal going to the position compensator in order to compensate for misclamping and imperfections in the data disk. The position compensator includes a tilt circuit which compensates for tilting of the disk drive from a non-horizontal position.