Tdk Corporation

Kazuo Fukunaga

Hideki Hirata

Giichi Shibuya

Yasufumi Takasugi

Kazuki Suzawa

Takashi Namioka

Toshikazu Hosobuchi

Masao Shigeta

Tsutomu Kotani

Norio Sato

Motoyoshi Fujita

Eiichi Suga

Minoru Higurashi

It is an object of the present invention is to provide an apparatus for discriminating an optical recording medium and a method for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is formed with periodical undulation in the circumferential direction thereof. The apparatus for discriminating an optical recording medium according to the present invention includes a first electrode, a second electrode, an alternate current signal generation circuitfor applying an alternate current A to the first electrode, a detection circuitfor detecting a level of an alternate current B appearing at the second electrode, and a control circuitfor controlling the operations of the alternate current signal generation circuitand the detection circuit

Apparatus for discriminating optical recording medium and method for discriminating optical recording medium

The present invention provides a method and an apparatus for discriminating the type of an optical recording medium and the number of recording layers in the medium. The apparatus includes a first electrode and a second electrode placed in the vicinity of a light transmission layer of the recording medium, an alternating current signal generation circuit for applying an alternating current A to the first electrode, a detection circuit for detecting the level of an alternating current B appearing at the second electrode, and a control circuit for controlling the operations of the alternating current signal generation circuit and the detection circuit, and a table provided in the control circuit.

It is an object of the present invention to provide an apparatus for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is warped and formed with periodical undulation in the circumferential direction thereof. The apparatusfor discriminating an optical recording medium according to the present invention includes a first electrodea second electrodea third electrodea fourth electrodean alternating current signal generation circuitfor applying an alternating current signal A to the first electrodeand the third electrodea detection circuitfor detecting the level of an alternating current signal Bappearing at the second electrodeand the level of an alternating current signal Bappearing at the fourth electrodea supporting mechanismfor supporting the first electrodeand the second electrodea supporting mechanismfor supporting the third electrodeand the fourth electrodea driving mechanismfor vertically moving the supporting mechanisma driving mechanismfor vertically moving the supporting mechanismand a control circuitfor controlling the operations of the alternating current signal generation circuitthe detection circuitthe driving mechanismand the driving mechanismand a tableis provided in the control circuit

It is an object of the present invention to provide an apparatus for discriminating an optical recording medium and a method for discriminating an optical recording medium which can reliably discriminate the kind of an optical recording medium even in the case where the optical recording medium to be discriminated is warped. The apparatus for discriminating an optical recording medium according to the present invention includes a first electrode, a second electrode, an alternating current signal generation circuitfor applying an alternating current signal A to the first electrode, a detection circuitfor detecting the level of an alternating current signal B appearing at the second electrode, a supporting mechanismfor supporting the first electrodeand the second electrode, a driving mechanismfor vertically moving the supporting mechanism, and a control circuitfor controlling the operations of the alternating current signal generation circuitand the detection circuitand the driving mechanism

The present invention relates to a magnetic sensor apparatus which is capable of detecting a very weak magnetic field even when the DC bias magnetic field is at zero and greatly reducing detection output occurring due to factors such as inconsistency of a magnetic body, temperature fluctuations, distortional fluctuations and drift. A magnetic sensor element S generates a pulse-type signal which is in proportion to a rate of change of the magnetic permeability of a magnetic body M and the size of an external magnetic field at a detection winding Wd. A drive circuit 11 cyclically changes the magnetic permeability of the magnetic body by supplying a pulse-type drive current for sampling to the magnetic body. A peak value detection unit 12 detects a positive peak value and a negative peak value of the pulse-type signal. A feedback circuit supplies an AC current which is in synchronization with the pulse-type drive current to the detection winding and also superimposes a DC current component on the AC current to set the absolute values of the positive peak value and the negative peak value equal to each other. The size of a magnetic field to be detected is detected based upon a DC current component at the detection winding.

Magnetic sensor apparatus

The improved structure of an inductor with an amorphous sheet core and a winding has been found. A core assembly has a pair of housing halves made of non-magnetic material with U-shaped track, in which a laminated amorphous sheet is mounted. The ends of the halves are inserted in a winding so that the ends of the cores abut with each other directly or through a gap spacer. The core halves are pressed by spring action to assemble the inductor. The core halves are produced by the steps of winding an amorphous sheet to a coil, inserting the coil in the track of the housing, and impregnating the coil with plastics.

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Tokyo, Japan

Kazuo Fukunaga