Victor Company of Japan, Limited

Seisuke Hiraguri

Akira Hirota

Takashi Uchimi

Yoshiteru Kosaka

Yoshihiko Honjo

A rotary magnetic head scanning control system in a magnetic recording and reproducing apparatus comprising a plurality of rotary magnetic heads and a head height position control mechanism, comprises a pilot signal generating circuit for generating a pilot signal during a recording mode, a circuit for controlling interruption of application of the pilot signal and a recording signal to each of the rotary magnetic heads, so that the pilot signal is supplied to one of the rotary magnetic heads together with the recording signal for a predetermined interval to record the pilot signal and the recording signal and thereafter interrupt application of the recording signal to the one rotary magnetic head to put the one rotary magnetic head into a reproducing state, and application of a recording signal to another rotary magnetic head is interrupted during a predetermined interval in which the other rotary magnetic head scans over a track part adjacent to a track part recorded with the pilot signal of a recorded track formed by the one rotary magnetic head to put the other rotary magnetic head in a reproducing state and thereafter supply the pilot signal to the other rotary magnetic head together with the recording signal for a predetermined interval to record the pilot signal and the recording signal, and a circuit for obtaining a control signal to be applied to the head height position control mechanism from the pilot signal reproduced as crosstalk from a track part adjacent to a scanning track, to apply the control signal thus obtained to the head height position control means and control the height positions of each of the rotary magnetic heads to become the same.

Rotary magnetic head scanning control system in a magnetic recording and

A pilot signal recording and reproducing system comprises a frequency generating circuit for successively generating a first frequency, a third frequency, a second frequency, and a fourth frequency in this order or in a reverse order for every recording unit of one track, where the first and second frequencies are mutually separated frequencies, selected from a first frequency group, and the third and fourth frequencies respectively are frequencies approximately equal to the first and second frequencies, selected from a second frequency group, a recording device for recording a frequency obtained from the frequency generating circuit as a pilot signal together with an information signal onto a recording medium, a comb filter for frequency-selecting pilot signals recorded on both sides of a track which is to be reproduced, where these pilot signals have mutually different frequencies and are included as crosstalk within a reproduced signal reproduced from the recording medium, a control circuit for controlling a delay time of a delay circuit within said comb filter and first and second filter circuits for respectively discriminating and separating pilot signals having mutually different frequencies obtained from the comb filter.

Pilot signal recording and reproducing system

A magnetic recording and/or reproducing apparatus has a tracking control device for performing tracking control by varying the height position of a rotary head which rotates to record and/or reproduce signals in an oblique track on a magnetic tape, according to a control signal applied to the tracking control device. The magnetic recording and/or reproducing apparatus comprises a detecting device for detecting the height position of the rotary head at a predetermined position within an angular range of the rotary head, where the rotary head does not make contact with the magnetic tape, and a control signal forming circuit for forming a control signal according to the output of the detecting device and supplying the control signal to the tracking control device to control the height position of the rotary head so that the height position becomes constant.

Magnetic recording and/or reproducing apparatus having a rotary head

A tracking control system is applied to a magnetic recording and/or reproducing apparatus in which magnetic heads (having gaps of mutually different azimuth angles) relatively scan a magnetic recording medium to record and/or reproduce an information signal thereon and/or therefrom. The tracking control system comprises a tracking reference signal supplying circuit for supplying a tracking reference signal to the magnetic heads so that the magnetic heads are positioned at a position where the recorded position of a tracking reference signal on both sides of the tracks adjacent to a certain track, is positioned successively shifted respectively along the track longitudinal direction with respect to the tracking reference signal recorded position at the above certain track. The magnetic head record the information signal together with the tracking reference signal. The tracking control system further comprises a discriminating circuit for discriminating the relative phase of a tracking reference signal reproduced from a reverse track which is adjacent to a normal track and recorded by a magnetic head having an azimuth angle different from that of a reproducing magnetic head, according to a tracking reference signal reproduced from the normal track which is recorded by a magnetic head having an azimuth angle identical to that of the reproducing magnetic head, tracking error signal deriving circuit for deriving a tracking error signal from the output signal of the discriminating circuit, and controlling circuit for controlling the relative scanning phase of the magnetic heads with respect to the track of the magnetic recording medium in response to the tracking error signal obtained by the tracking error signal deriving circuit. The frequency of the tracking reference signal supplied by the tracking reference signal supplying circuit is selected so that the level of the tracking reference signal reproduced from the normal track is always higher than that of the tracking reference signal reproduced from the reverse track.

Tracking control system in a magnetic recording and/or reproducing

A tracking control system is used in a magnetic reproducing apparatus which comprises a rotary magnetic head for successively reproducing recorded signals from parallel tracks existing obliquely with respect to the longitudinal direction of a magnetic tape. The tracking system comprises a head swinging mechanism for varying the height position of the rotary magnetic head, and swinging the tracing position of the rotary magnetic head with respect to the track of the magnetic tape in the width direction of the track, a head swinging voltage generating circuit for generating a head swinging voltage, one or a plurality of memories for sampling and memorizing a voltage which is to be supplied to the head swinging means, at a point in time corresponding to when the rotary magnetic head passes one or a plurality of predetermined relative tracing positions respective of the magnetic tape, a level detecting circuit for detecting the level of a signal reproduced by the rotary magnetic head at a point in time identical to that of the above, a maximum level detecting circuit for detecting whether the level detected by the level detecting circuit has reached a maximum, a control circuit for enabling the reading-out of the voltage memorized in the memory upon detection of the maximum level by the maximum level detecting circuit, and an adding circuit for adding the voltage read out from the memory and the head swinging voltage supplied from the head swinging voltage generating circuit, and supplying the added voltage to the head swinging mechanism.

Tracking control system in a magnetic reproducing apparatus

A time compression or expansion circuit for audio signals comprises an analog to digital converter (12), a random access memory (17), a latch circuit (18), a digital to analog converter (19), a clock pulse generator (13), a counter circuit (14), a data selector (16), and a timing controller (13). The timing controller (15) is supplied with a clock pulse from the clock pulse generator (13) and a timing signal from the counter circuit (18), and produces a series of writing-in pulses and a series of strobe pulses which exist alternately and have a common frequency regardless of the mode of compression or expansion or rate thereof. The analog to digital converter (12) converts an input audio signal (11) to a digital signal in response to a writing-in and reading-out switching pulse from the counter circuit (18). The random access memory (17) writes the signal from the analog to digital converter (12) in response to the writing-in pulse fed from the timing controller (15), into an address thereof designated by an address datum for writing-in, and reading a signal out of an address thereof designated by an address datum for reading-out in response to the strobe pulse of the common frequency in such a way that the written address of the memory is read multiple times or skipped being read according to the mode and rate. The latch circuit (18) holds the signal read out from the random access memory (17) in response to the strobe pulse from the timing controller (15).

Circuit for time compression and expansion of audio signals

A video signal reproducing system comprises a tape on which video signals are recorded along video tracks, which extend obliquely to the longitudinal direction of the tape with substantially no space therebetween. A control signal is recorded along a control track extending in the longitudinal direction, the video tracks being recorded by a plurality of rotating video heads having gaps of mutually different azimuth angles. The control signal is recorded along the control track interrelatedly with the recording of the video tracks by the video heads. A motor drives the tape in tape travel or stops the tape. A plurality of rotating, reproducing video heads successively trace the video tracks to pick up and reproduce the recorded video signals. The rotating video heads have gaps which have mutually different azimuth angles that are respectively the same as the first mentioned azimuth angles, and which have different height positions above the plane of rotation of the centers of the tracks in the width direction thereof. The control signals are reproduced from the control track of the traveling tape. A circuit delays the reproduced control signal by a specific time to obtain a delayed signal and uses this delayed signal to stop the motor and therefore the tape travel. The tape is stopped at a position relative to the reproducing video heads at which the reproduction is accomplished so that the time instant when the level of the reproduced video signal becomes a minimum is within or in the vicinity of the vertical blanking period.

System for reproducing a video signal in a slow motion or still picture

A jitter measuring apparatus forms a circuit for detecting the jitter component found in an input signal. A jitter indicating line signal is generated in response to the detected jitter component. At least one reference line signal is generated at a time point which deviates from the jitter indicating line signal. The jitter indicating line signal is supplied to a television receiver which displays it as a line which extends vertically and sways horizontally on the picture screen. The reference line signal is supplied to the television receiver where it is displayed as a reference line extending vertically at a reference position, for the jitter indicating line on the picture screen.

Jitter measuring apparatus

A system for controlling the rotation of a direct current motor has an armature resistance control circuit. An operational amplifier has one input terminal connected to the direct current motor and another input terminal connected to form a differential amplifier. A first resistor is connected between an output terminal of the operational amplifier and one of the input terminals. A second resistor is connected between the other input terminal of the operational amplifier and a terminal for applying a control signal voltage thereto. A third resistor is connected between the output terminal of the operational amplifier and the other input terminal. The rotational phase of a structure rotated by the direct current motor produces a phase detection signal. A phase comparing means compares the phase detection signal with a reference signal and applies the resulting output, phase comparison error signal as a control signal voltage. The armature resistance and the first, second, and third resistors are connected as a bridge circuit.

System for controlling the rotation of a DC motor

A switching circuit connects a magnetic head in a magnetic recording and reproducing apparatus. The magnetic head is used for recording and reproducing signals onto and from a magnetic recording medium. The switching circuit comprises a first electronic switch connected between ground, the output side of a recording amplifier, and one terminal of the magnetic head. The switch becomes nonconductive during the recording mode and becomes conductive during the reproducing mode. A second electronic switch circuit is connected substantially between ground, the other terminal of the magnetic head, and the input side of a reproducing amplifier. The second switch becomes conductive during recording and nonconductive during the reproducing mode.

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Yokohama, Japan

Seisuke Hiraguri