Industrial Technology Research Institute

Carl Y Yang

Der-Ray Huang

Jau-Jiu Ju

Mark O Freeman

Tzu-Ping Yang

Hsi-Fu Shih

Chieh-Chih Li

Chien-Li Hung

Wei-Chih Lu

Jen-Yu Hsu

The present invention discloses a multiple-beam holographic optical pick-up head, which has the advantages of the multiple-beam optical pick-up head and the holographic optical pick-up head and can increase the light usage efficiency. This invention uses the property that a polarized diffractive optical element can generate different optical effects for laser beam with different polarizations and places a polarized multiple-beam grating and polarized hologram on the optical path for splitting the incident light toward the disc into multiple reading beams by the multiple-beam grating. The returning laser beams reflected from the disc are diffracted and diverted by the hologram to reach a photodetector. Both the incident and reflective beams are diffracted once only; thus the light usage efficiency can be increased.

Multiple-beam holographic optical pick-up head

A track-number seeking algorithm and a seeking means for the dynamic modification of the computation of track numbers in an optical storage device employs a down counter, an up counter and a microprocessor. First, a rotation number of an optical storage disk in the microprocessor, a track error zero crossing signal of the down counter and the up counter are reset, a static track seeking number of the down counter is set, and a seeking operation is performed. The seeking operation reads the rotation number and the track error zero crossing signal, computes a residual track number, and judges whether an overflow flag is to be sent. If the overflow flag is sent, then, the rotation number is added, a pulse number of a feedback signal is reset, and the next step is to judge whether the seeking operation is outward or not. If the overflow flag is not sent, the next step is to judge directly whether the seeking operation is outward or not. Next, if the seeking operation is outward, and the residual track number is equal to the rotation number, the seeking operation is terminated; otherwise, the seeking operation is repeated. If the seeking operation is inward, and the residual track number is equal to the negative value of the rotation number, the seeking operation is terminated; otherwise, the seeking operation is repeated.

Track-number seeking algorithm and seeking means for dynamic modification of track numbers computing in an optical storage device

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Chutung Hsinchu, Taiwan

Carl Y Yang