Sony Corporation

Toshiya Murakami

Minoru Tobita

Shiro Morotomi

Kazuo Murayama

Kunihiro Shioura

Atsushi Umezawa

Tsukasa Wadamori

A reproduction apparatus for an optical recording medium that has a convex pit recording layer, in which pits are formed in a convex shape viewed from a laser incidence side, and a concave pit recording layer, in which pits are formed in a concave shape viewed from the laser incidence side, as recording layers in which data is recorded by pit strings, the pits being formed with a depth that is set in a range of &#x3bb;/4.5 to &#x3bb;/6 with respect to a laser wavelength &#x3bb;, including: an optical head section that irradiates laser beams on the recording layers and detects reflected light information to read out information recorded in the recording layers; a tracking error signal generating section that generates a tracking signal; a polarity switching section that switches a polarity of the tracking error signal; and a tracking servo section that performs a tracking servo operation.

Optical recording medium, reproduction apparatus, and tracking servo method

A sound quality adjustment circuit including a status variable type active band-pass filter having an amplification circuit fed with an input signal and an integration circuit, and a controller for controlling the conversion conductance of the amplification circuit. The center frequency of the status variable type active band-pass filter is continuously varied by controlling the conversion conductance of the amplification circuit by the controller.

Sound quality adjustment circuit

A laser power control circuit for controlling the laser power is provided in an automatic power control circuit of an optical disc device, an amplitude of an RF signal is examined by the LPC circuit, a control voltage to be applied to the APC circuit is generated, and feedback is applied to control the laser power and stabilize the RF signal level. By this, the reproduction can be stably carried out by even discs having different reflection rates, an improvement of the reproduction capability can be achieved, and a lowering of the optical output of the laser diode accompanied with aging and the lowering of the reproduction capability accompanied with the lowering of the optical output due to dust adhered to the pick-up can be prevented. Further, the laser power per se is controlled, so there is no effect on the band of the RF amplifier.

Growing community of inventors

Kanagawa, Japan

Toshiya Murakami