Industrial Technology Research Institute

Pei-Yih Liu

Jau-Jiu Ju

Shin-Ter Tsai

Tsung-Ming Yang

Zu-Wen Chao

A focusing and tracking method and system for use on the read/write head of an optical drive is provided. The focusing and tracking method and system is capable of detecting both the focusing error and the tracking error of the read/write head to thereby control the focusing and tracking of the same during read operation. In particular, this focusing and tracking method and system combines the use of a knife-edge focusing method and a push-pull tracking method respectively for focusing and tracking of the read/write head. A specially designed photo detector is used to obtain both the focusing error signal and the tracking error signal. This allows the focusing and tracking system to be simplified in structural complexity, thereby saving manufacturing cost. Moreover, since the focusing error signal and the tracking error signal are obtained respectively in perpendicular directions, the undesired effect of cross-talk between the two error signals can be avoided.

Focusing and tracking method and system for the read/write head of an

A two-wavelength laser pick-up head used for accessing DVD, CD, CD-R and CD-E systems. The two-wavelength laser pick-up head includes a shorter wavelength laser optical path for reading the data from a DVD system, and a longer wavelength laser optical path for reading the data from a CD or CD-R system. The above two optical paths use the same collimator and the same objective lens. There is a compensator lens which is used in the longer wavelength laser optical path for correcting the spherical aberration due to the thick substrate of the CD or CD-R.

Two-wavelength laser pick-up head for a DVD

A grating pattern for a bifocal optical pick-up head assembly of an optical compact disc drive device is disclosed. The device is capable of accessing data on the surface of compact discs arranged in either the DVD or the CD formats. The optical head assembly has an optical system that includes a grating plate and an objective, wherein the grating plate contains the grating pattern, and the objective focuses a light beam onto the data surface of the accessed compact disc. The grating pattern includes a first region that contains no grating and a second region that contains grating. The first region substantially surrounds the second region. The light beam that passes through the first region of the grating pattern is incident to the cross-sectional aperture of the objective for the DVD format of the accessed optical disk. The light beam that passes through the second region of the grating pattern is incident to the cross-sectional aperture of the objective for the CD format of the accessed optical disk.

Optical grating for a bifocal access head of optical disk drive devices

A single-lens optical pick-up head has a laser diode, a beam splitter, a collimator, a polarizing light converter, a polarization controller, a polarizing beam splitter, a first quarter-wavelength plate, a mirror, a second quarter-wavelength plate, a convex mirror, an objective lens and a photodetector, for use in accessing DVD and CD discs by switching its optical property between two states.

Growing community of inventors

Changhua Hsien, Taiwan

Pei-Yih Liu