Tdk Corporation

Fuji Electric Co., Ltd.

Shuji Tsukamoto

Masato Takahashi

Hiroyuki Arioka

Masahiro Shinkai

Narutoshi Fukuzawa

Atsuko Kosuda

Takahiro Kudo

Toshiki Aoi

Michihiko Tsuruoka

Motohiro Inoue

Takashi Horai

Hiroshi Take

Kimihiro Nakamura

Nobuhisa Kato

It is an object of the present invention to provide a multilevel optical recording medium in which influence of variation in characteristics of a recording layer in a plane of the recording layer on reproduced data can be corrected The multilevel optical recording medium according to the present invention includes at least a recording layerand is constituted so that data can be recorded therein in a multilevel manner by controlling a state of the recording layeramong multiple stages and the multilevel optical recording medium according to the present invention is characterized in that a plurality of calibration signals are stored in the recording layerAccording to the thus constituted multilevel optical recording medium, since an optical data recording and reproducing apparatus can detect and correct for the variation in characteristics of the recording layerin the plane thereof, even in the case where variation in characteristics of the recording layerin the plane thereof is present, data recorded in the multilevel optical recording medium in a multilevel manner can be read in a desired manner.

Multilevel optical recording medium with calibration signals

An optical recording medium adapted for high density recording with a light of short wavelength which exhibits excellent jitter properties, and its recording method are provided. The optical recording medium recorded and/or reproduced with a light at a wavelength of 600 to 680 nm comprises a substrate having grooves formed on its surface at a track pitch of up to 0.8 .mu.m, and a recording layer containing an organic die disposed on the substrate. Depth A and width B of the groove (.mu.m) and leveling ratio C are in the relation:

Optical recording medium for use at short wavelengths and its recording

A capacitance-based pressure detecting apparatus detects a pressure applied to a diaphragm based on a capacitance which varies depending on the change in portion of the diaphragm. The pressure detecting apparatus comprises a diaphragm which changes position depending on a differential pressure between a first pressure and a second pressure, a first electrode which is provided opposite a first plane of the diaphragm and forms, together with the diaphragm, a first capacitor, a second electrode which is provided opposite a second plane of the diaphragm and forms, together with the diaphragm, a second capacitor, a third capacitor altering a capacitance according to the first pressure, a detecting unit for detecting the capacitance of the first through third capacitors, and an operation unit for obtaining a pressure applied to the diaphragm based on the capacitance of the first and second capacitors, and amending the obtained pressure based on the capacitance of the third capacitor.

Pressure detecting apparatus for measuring pressure based on detected

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Tokyo, Japan

Shuji Tsukamoto