Pioneer Corporation

Akinori Ohkubo

Takuma Yanagisawa

Takayuki Nomoto

A tilt angle detection device and method which generates, as a first push-pull signal, a difference between light reception signals corresponding to two light receiving surfaces of one side of a photodetector, which are divided along the track tangent direction; generates, as a second push-pull signal, a difference between the light reception signals corresponding to two light receiving surfaces of the other side of the photodetector; and generates a tilt signal that indicates a tilt angle defined by a normal on the recording surface of the optical recording medium at a position of irradiation of the laser beam and the optical axis of the laser beam in accordance to a difference between amplitudes of the first and second push-pull signals.

Tilt angle detection device and method utilizing pattern identification

A focus servo device is for focusing a light irradiated from a light source onto a recording medium surface via an objective lens. Assuming that a wavelength of the light is &#x3bb;, a numerical aperture of the objective lens is NA, an average run length period of the recording medium standardized with &#x3bb;/NA is RL, the track pitch standardized with &#x3bb;/NA is TP, and the capture range of said focus servo device is CR [&#x3bc;m], the following equation applies:0.114/(&#x2212;0.72)+0.84&#x2266;&#x2266;18000(&#x2212;0.69)+3.13.

Focus servo device

An optical disk has a recording layer recording information as a row of marks and non-marks alternately appearing in a groove formed at a track pitch of 0.280 &mgr;m or greater and a light transmissive layer formed over the recording layer, to reproduce information due to a light beam having a wavelength in a range of 375 nm to 415 nm and illuminated by an objective lens having a numerical aperture NA in a range of 0.80 to 0.90 through the light transmissive layer to the recording layer. The groove has a depth in a range of 18 nm to 32 nm.

Growing community of inventors

Tsurugashima, Japan

Akinori Ohkubo