Pioneer Electronic Corporation

Hitachi, Ltd.

Katsuji Mizumoto

Yasuo Kominami

Masahiro Yamamura

Toshihide Hanada

Mutsumi Kono

An apparatus for reproducing information from a recordable optical disc having an information recording area for recording a plurality of information pieces and an index information recording area for recording index information with respect to the plurality of information pieces. The apparatus includes a driving device for rotationally driving the optical disc, a pickup device for irradiating a light beam onto the optical disc so as to read information recorded on the optical disc, a transferring device for transferring the pickup device in a radial direction of the optical disc, a memory for storing a temporary index information, and a control device for controlling the driving device, the pickup device and the transferring device and for producing the temporary index information on the basis of a read information read by the pickup device. The control device produces and stores the temporary index information into the memory when no index information is recorded on the index information recording area. Accordingly, desired information can be reproduced from the program area of a partial disc.

Method and apparatus for reproducing information from a recordable

Recorded information is reproduced from a recordable optical disc with a light beam applied from an optical pickup to the recordable optical disc. The recordable optical disc has a program area for recording main information, a PMA area for recording recording history information relative to main information which is in the process of being recorded in the program area, and a lead-in area for recording, as index information, recording history information relative to main information which has fully been recorded in the program area. While the recordable optical disc is at rest, it is determined whether index information is recorded in the lead-in area, and if index information is not recorded in the lead-in area, the optical pickup is moved to a region of the PMA area where the recording history information is recorded, while the recordable optical disc is at rest After the optical pickup has reached the region, the optical pickup reads the recording history information while the recordable optical disc is being rotated. After the recording history information has been read from the region, the optical pickup is moved to the program area while the recording optical disc is being rotated at a constant speed.

Method of and apparatus for playing back recordable optical disc

A driving circuit for a two-phase brushless motor includes a servo control device operating to make constant the phase difference between a sum signal indicative of the current sum flowing through the motor coils and a positional signal indicative of the relative position of the motor rotor and the coils.

Two-phase brushless motor driving circuit

This invention relates to a constant voltage output circuit using, as its reference potential source, power source feed terminals for feeding a power source voltage to a reference potential source of a given circuit. The constant voltage output circuit includes a series circuit of an npn transistor and a pnp transistor interposed between the reference potential source of the given circuit and the power source feed terminals, means for biasing the base potential of the pnp transistor by a predetermined potential with respect to the potential of the power source feed terminals, and an emitter follower circuit disposed in the collector output circuit of the npn transistor of the series circuit, and forming a negative feed-back circuit.

Constant voltage output circuit

The present invention is related to a temperature-compensated circuit for controlling the drive of a motor, comprising a differential comparator for comparing a running-speed signal of a motor with a reference signal, and a feedback amplifier having a differential amplifier to which is given an input offset.

Circuit for controlling the drive of motor

A differential amplification is disclosed which comprises differential paired transistors. The direct bias current flowing in the differential paired transistors is determined by a constant current flowing from a first constant current circuit connected to the emitters of the differential paired transistors. The collector current of one of the differential paired transistors is caused to flow as an input current in a high-precision current mirror circuit. The current value of the constant current flowing in the first constant current circuit is set at 2Io. Since a direct base current Ib flows in the differential paired transistors, the current value of the collector current of one of the differential paired transistors is (Io-Ib). Accordingly, the high-precision current mirror circuit generates an output current of a current value of (Io-Ib) at the output terminal thereof. The differential amplification circuit includes a second constant current circuit having a current value Io corresponding to 1/2 of the current value of the constant current flowing in the first constant current circuit. A bias transistor is connected between the high-precision current mirror circuit and the second constant current circuit, and the direct base current Ib flows in this bias transistor. Accordingly, in the equilibrium state between the differential paired transistors, the output current appearing at the output terminal of the high precision current mirror circuit becomes zero, and the offset output current can be eliminated or moderated.

Growing community of inventors

Sayama, Japan

Katsuji Mizumoto