Sharp Kabushiki Kaisha Corporation

Makoto Horiyama

Takahiro Miyake

Nobuo Ogata

Yasuo Nakata

Kohji Minami

Masaru Ogawa

Shigeru Uchida

Chiaki Kiyooka

Yoshinori Kajiwara

A conventional optical disk apparatus detects the amount of shift of an objective lens with a tracking error signal and an RF signal, and controls, when an optical pickup is moved, the shift amount for performing high-speed seek and high-speed access. The problem here is that this apparatus cannot be applied to an optical disk having an area where no RF signal is recorded, and requires higher costs. In view of this, an optical disk apparatus of the present invention has a shift signal detecting portion that detects a shift signal based on a push-pull signal generated during generation of a tracking error signal based on the reflected light resulting from a beam reflected from an optical disk, and a shift amount control portion that drives, when an optical pickup is moved, an objective lens actuator based on the shift signal detected by the shift signal detecting portion.

Optical disk apparatus

An optical pickup () projects a read beam onto an optical disc () as an optical storage medium which is driven to rotate by a spindle motor () and receives its reflection. A laser beam from a laser producing element () passes through a liquid crystal panel () and guided to an objective lens (). The panel () is provided to correct spherical aberration caused by an irregular thickness of a transparent substrate of the optical disc (). A control circuit () changes a spherical aberration correction signal SA to carry out sampling more than once, covering a range of the output of an optical sensor () where the output shows large changes. The circuit () determines the position of a peak of an approximation curve through calculation and designates that position as the magnitude of correction. Thus, the optical pickup () can quickly and accurately detect the magnitude of the correction of the spherical aberration caused by an irregular thickness of the optical disc ().

Optical pickup spherical aberration compensating method, optical pickup spherical aberration focus offset compensating method, and optical pickup device

In an integrated optical unit of the present invention, a photo detector () and a holding member () that sustains a semiconductor laser () are provided on a polarizing beam splitter (). This makes it possible to reduce a deviation from a designed value due to tolerance, and adjust a relative positional relationship between the semiconductor laser () and the photo detector (). Therefore, returned light from an optical disk () is accurately adjusted with respect to a division line of a photo-detecting device (). As a result, stable servo-control is realized, and an information signal with fine quality is obtained.

Integrated optical unit, adjusting method therefor, and optical pickup

An object of the invention is to provide a structure for suppressing occurrence of a track offset in a tracking control using DPP method, and simplified apparatus assembly adjustment. When a diffraction grating provided in an optical pick-up apparatus, diffracts light irradiated from a semiconductor laser at least into zero-order diffraction light and &#xb1; first-order diffraction light, disposed adjacent to diffraction area alternately in an extension direction of a grating groove, and an effective diameter of light beam with which the diffraction grating is irradiated is D, and a number of divisions into which the effective diameter D is divided is m (m is an integer of 3 or more), a width Wand a width Ware formed to meet WWD/m.

Optical pick-up apparatus

Beam shaping means may have a shaping ratio set to allow a light beam emitted from a semiconductor laser and having an elliptic intensity distribution to have an ellipticity of no more than two to obtain a spot achieving high light availability and reduced in size. Furthermore, the shaping ratio can be set to no more than 2.5 to allow a polalized-beam splitter (light separation means) and other components to be arranged in a converged flux passing between the semiconductor laser and a collimator lens.

Growing community of inventors

Nara, Japan

Makoto Horiyama