JPS6252750A - Magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To eliminate the need for a control track by recording a vertical synchronizing signal included in a luminance signal recorded on a magnetic tape by a rotary magnetic head while applying modulation different in degree from an odd number order and an even number order. CONSTITUTION:A pulse generated from a pulse generating circuit 21 is superim posed on the vertical synchronizing part of a luminance signal by an adder circuit 19, a changeover switch 20 is interlocked with a changeover switch 18 and switched in synchronizing with a head changeover pulse. That is, a pulse from the pulse generating circuit 21 is superimposed on the vertical syn chronizing signal at every other pulse and the degree of the modulation of the vertical synchronizing signal differs at every other interval when FM modula tion is applied. Thus, even when no control signal is recorded onto a control track, sufficient tape running servo for signal reproduction is attained by repro ducing the vertical synchronizing signal different from the signal waveform at odd and even number orders.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magnetic recording and reproducing apparatus in which a vertical synchronizing signal can be used as a control signal for tape running servo.

[Prior Art] A magnetic recording/playback device that records video or audio signals on a magnetic tape using a pair of rotating magnetic heads with different azimuths keeps the feed of the magnetic tape and the rotational phase of the rotating magnetic head constant during signal playback. A method is adopted in which the control signals necessary to maintain the relationship are recorded on control tracks along the side edges of the magnetic tape. A conventional magnetic recording/reproducing apparatus 1 shown in FIG. 3 includes a drum motor 3 provided in a head drum assembly 2 containing a pair of rotating magnetic heads 2a and 2b, and a capstan motor 5 for running a magnetic tape 4. Rotation is controlled by commands from the servo circuit 6. Servo circuit 6
controls the feeding of the magnetic tape 4 on the basis of information from the control head 7 that reads control signals recorded on the control track of the magnetic tape 4 during recording, and rotational information regarding the two motors.

[Problems to be Solved by the Invention] The conventional magnetic recording and reproducing device 1 described above has a control track and an audio track on both sides of the magnetic tape 4,
A control head 7 and an audio head 8, which are fixed magnetic heads, record control signals and audio signals, respectively.

For this reason, when the audio signal has two left and right channels, it is necessary to record the audio track by dividing it into two parts for the left and right channel signals. Since the area is limited, there are problems such as the dynamic range and frequency range of recorded audio are restricted and the S/N ratio is deteriorated.

[Means for Solving the Problems] The present invention solves the above problems, and uses a vertical synchronization signal in a luminance signal recorded on a magnetic tape via a pair of rotating magnetic heads with different azimuths. a modulating means for modulating odd and even numbers with different signals, and having substantially the same azimuth as one of the pair of rotating magnetic heads, and distinguishing between the odd and even vertical synchronization signals. The gist is that a fixed magnetic head for reproduction is provided.

[Function] This invention records a vertical synchronizing signal included in a luminance signal recorded on a magnetic tape by a rotating magnetic head, with different degrees of modulation applied to the odd and even numbers. A fixed azimuth magnetic head selectively reproduces odd-numbered and even-numbered vertical synchronization signals and provides them to tape running servo.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1.2. 1 and 2 are a schematic circuit diagram and a signal waveform diagram of each part of the circuit, respectively, showing an embodiment of the magnetic recording/reproducing apparatus of the present invention.

In FIG. 1, the basic circuit configuration of a magnetic recording/reproducing device 11 is that a video signal to be recorded is supplied to a low-pass filter circuit 13 via an automatic gain control circuit 12. The luminance signal separated at
After high-frequency emphasis is applied in the FM modulation circuit 16, F
0 is configured to be modulated by M and supplied to the recording amplifier circuit 17.
After the color signal is subjected to low frequency conversion processing, it is sent to the recording amplifier circuit 1.
7 is added to the FM modulated luminance signal.

A pair of rotating magnetic heads 2a and 2b are connected to the recording amplifier circuit 17 via a changeover switch 18 that is changed over by a head changeover pulse.

By the way, an adder circuit 19 is interposed between the clamp circuit 14 and the emphasis circuit 15.
9 is connected to a pulse generating circuit 21 via a changeover switch 20 that is linked to the changeover switch 18.

The pulse generating circuit 21 generates a pulse at a constant level in the vertical synchronization signal of the luminance signal output from the clamp circuit 14, and this pulse is used as a control signal during reproduction.

A fixed magnetic head 22 has the same azimuth as the rotating magnetic head 2a, and is fixed along the vertical synchronizing signal recording portion of the video track formed on the magnetic tape 4, and plays the role of a control head during signal reproduction. Fulfill.

Here, the pulse generated by the pulse generation circuit 21 is superimposed on the vertical synchronization portion of the luminance signal by the addition circuit 19.

In this case, the changeover switch 20 is linked to the changeover switch 18 and is switched in synchronization with the head switching pulse, so the pulse is superimposed on the vertical synchronization signal only when one of the rotating magnetic heads 2a records a signal. Ru.

That is, every other pulse from the pulse generation circuit 21 is superimposed on the vertical synchronization signal. Therefore,
The luminance signal shown in FIG. 2 (A), which is the output of the clamp circuit 14, becomes as shown in FIG. , the degree of modulation of the vertical synchronization signal is 1
It will be different for each individual.

On the other hand, when reproducing signals, the vertical synchronization signal recorded by the rotary magnetic head 2a and the vertical synchronization signal recorded by the rotary magnetic head 2b are differentially reproduced by the fixed magnetic head 22.

That is, since the vertical synchronizing signal recorded by the rotating magnetic head 2a and the vertical synchronizing signal recorded by the rotating magnetic head 2b have different frequencies when subjected to FM modulation, they are differentially reproduced by the fixed magnetic head 22. In particular, the vertical synchronization signal recorded by the rotating magnetic head 2a is reproduced as a high-level signal by the fixed magnetic head 22 having the same azimuth.

In this way, the vertical synchronization signal detected by the fixed magnetic head 22, like the control signal detected by the conventional control head 7, can identify the rotating magnetic heads 2a and 2b during reproduction, and can be used for the tape running servo. .

In this way, the magnetic recording/reproducing device 11 modulates the vertical synchronizing signal included in the luminance signal recorded on the magnetic tape 4 by the rotating magnetic heads 2a and 2b with different signals for the odd and even numbers, and Since the configuration is such that the fixed magnetic head 22 with almost the same azimuth as the magnetic head is configured to discriminately reproduce the odd and even vertical synchronization signals, the signal waveform can be reproduced evenly and oddly without recording the control signal on the control track. By reproducing different vertical synchronization signals at the 1 and 2, it is possible to perform sufficient tape running servo during signal reproduction, and as a result, unnecessary control tracks can be used for recording audio signals, etc.

[Effects of the Invention] As explained above, according to the present invention, the vertical synchronization signal included in the luminance signal recorded on the magnetic tape by the rotating magnetic head is modulated with different signals for the odd and even numbers, and one Since the fixed magnetic head with almost the same azimuth as the rotating magnetic head is configured to discriminately reproduce the odd and even vertical synchronization signals, the signal waveform can be reproduced evenly and oddly without recording the control signal on the control track. By reproducing different vertical synchronization signals, sufficient tape running servo is possible during signal reproduction, and this provides excellent effects such as the ability to use unnecessary control tracks for recording audio signals, etc. play.

[Brief explanation of the drawing]

1 and 2 are a schematic circuit configuration diagram and a signal waveform diagram of each part of the circuit, respectively, showing an embodiment of the magnetic recording/playback device of the present invention, and FIG. 3 is a schematic circuit configuration showing an example of a conventional magnetic recording/playback device. It is a diagram. 2a, 2b... Rotating magnetic head, 4... Magnetic tape, 11... Magnetic recording/reproducing device, 16... FM modulation circuit, 18.20... Changeover switch, 21... Pulse generation circuit , 22...Fixed magnetic head.

Claims (1)

[Claims] a modulation means for modulating a vertical synchronization signal in a luminance signal recorded on a magnetic tape through a pair of rotating magnetic heads having different azimuths with different signals for odd and even numbers, and of the pair of rotating magnetic heads, A magnetic recording/reproducing apparatus comprising a fixed magnetic head having substantially the same azimuth as one rotating magnetic head and selectively reproducing the odd-numbered and even-numbered vertical synchronization signals.