Sony Corporation

Tokyo Gas Company Limited

Hakko Co., Ltd.

Isao Saito

Naofumi Yanagihara

Yukio Kubota

Keitaro Yamashita

Yoshiki Shirochi

Toshihiko Numakura

Motoyuki Koga

Takashi Kamuro

Hisao Ootsuga

A magnetic playback apparatus and method with which a PLL phase-locked to played-back data operates stably even when the magnetic tape on which the data is recorded is transported at a high speed of several hundred times the recording speed. During high-speed playback of a magnetic tape, the speed of the magnetic tape is detected and using this tape speed information the free-run frequency of a PLL 2 is corrected in correspondence with the azimuth angles of magnetic heads HO, HE. The rotational period of a drum servo 3 is also corrected using the tape speed information.

Magnetic playback apparatus and method

In rotary head reproducing apparatus of the type having heads which scan successive tracks on a record medium that is movable at a controllable speed, wherein such tracks contain a pattern of tracking control signals that are used by a servo control arrangement to determine and correct tracking errors, at least one of the tracking control signals that are reproduced from the tracks is detected, and if that tracking control signal is not sensed for a predetermined time interval, the speed at which the record medium is driven is changed to a predetermined speed (e.g. greater or less than the normal speed), thereby forcing tracking errors. This prevents lock-up which could occur when the tracks which are scanned by the heads are precisely out-of-phase from the correct tracks.

Tracking control which avoids lock-up for rotary head reproducing

A tracking control apparatus for a rotary head type recording unit having a first rotary head and a second rotary head for forming pairs of slant tracks on a magnetic type, each track having a head entering side tracking region and a head leaving side tracking region. First and second pilot signals of different frequencies are recorded in the head entering and head laving sides tracking region, with the first pilot signal being recorded at a predetermined position on the first track which precedes (in the track direction) the second pilot signal recorded at a predetermined position on the second track adjacent to the first track.

Tracking control apparatus of rotary head type recording unit using

A video tape recording apparatus includes a rotary magnetic head for scanning skewed recording tracks on a video tape, a device for recording a video signal in each of the recording tracks by the rotary magnetic head, a device for providing a first guard band area in each of the recording tracks next to the video signal recorded in the respective recording track, a device for recording a first audio signal next to the first guard band area by the rotary magnetic head, a device for providing a second guard band area next to the first audio signal in each of the recording tracks with the second guard band area having a length different from the length of the first guard band area, a device for recording a second audio signal next to the second guard band area by the rotary magnetic head, and a device for recording an index signal in a longer one of the first and second guard band areas by the rotary magnetic head.

Rotary magnetic type recording apparatus

An anti-piracy signal generating circuit for generating anti-piracy signal components on a video signal reproduced by a first video unit, the signal components being interleaved to a frequency f.sub.H in the band of the video signal in accordance with the video signal components and a signal superimposing circuit for superimposing the anti-piracy signal components intermittenly on the luminance signal, first color difference signal, and second color difference signal.

Anti-piracy video tape system has anti-piracy components added to the

A tracking control device for a video tape recorder comprises a bimorph leaf on which a rotary playback head is mounted so as to be deflectable in a direction perpendicular to tracks to be scanned. A triangular wave signal generating circuit comprising cascaded flip-flops generates a substantially triangular wave signal which is supplied to the bimorph leaf to cause the playback head to wobble relative to the tracks. A detecting circuit detects an envelope signal in the signal reproduced by the playback head, and a phase comparing circuit which includes an exclusive-OR circuit compares the phase of this envelope signal with the phase of the triangular wave signal. The output of the phase comparing circuit is fed back to the bimorph leaf to effect tracking correction.

Tracking control devices for video tape recorders

A magnetic reproducing apparatus comprises two rotary magnetic heads mounted on respective bimorphs, the heads being displaceable in the transverse direction relative to recorded tracks on a magnetic tape is response to control voltages applied to the respective bimorphs to effect correct scanning of the tracks, a pulse generator for generating a first pulse signal of frequency dependent on the transport speed of the tape, a first counter for counting the pulses of the first pulse signal to produce a first count output each time a head completes scanning of a track, a second counter which, starting from the first count output, counts the pulses of a second pulse signal which has a frequency which is an integral multiple of the frequency of the first pulse signal and produces a second count output, and a circuit to derive from the second count output control voltages for supply to the bimorphs to preset the positions of the heads relative to the tracks each time a head is to start scanning a track. The apparatus further comprises a third counter for counting the pulses of the first pulse signal to produce a respective third count output corresponding to each scan of a track by a head, a subtractor to derive a difference output from each third count output and the immediately preceding third count output, and an adder to add the difference output to the second count output prior to supply to the circuit for deriving the control voltage, whereby the control voltages are modified in dependence on acceleration or deceleration of the transport speed of the tape.

Magnetic reproducing apparatus with head positioning circuit

A method for repairing pipes laid underground, such as gas pipes, consisting of a main supply pipe from which numerous distribution pipes branch off to supply the individual users, the method using resin to repair the main supply pipe and the distribution pipes from the inside while in their buried state. The repair method of this invention is characterized by the fact that, having repaired the main supply pipe and the distribution pipe in successive operations, whether the repairs to the main supply pipe and the distribution pipes have been done properly or not can be confirmed on completion of the repairs by carrying out sealage tests on the distribution pipes and the main supply pipe.

Method of repairing pipes laid underground

A battery-operable video tape recorder includes a rotary magnetic head which during normal operation is driven at a predetermined speed controlled by a servo circuit. In the pause mode of the recorder the rotary magnetic head is driven at a lower, uncontrolled speed to reduce power consumption. Release of the pause mode may be delayed until the servo circuit has locked following a pause.

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Kanagawa, Japan

Isao Saito