JPS61148658A - Magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain improved phase control characteristics by comparing the phases of a signal which is subjected to 2/3-division from the output of the revolutionary phase detector of a head cylinder and of a signal which is subjected to 1/2-division of the vertical synchronizing signal output, to control by the output of the said comparison the head cylinder motor so that the both signals synchronize with each other. CONSTITUTION:The signal S22 from a PG7 that detects the revolutionary phase of a rotation head cylinder 3 is divided by a 1/3-dividing circuit 28 to make 1/3-division which is made to a signal S23. A signal S21 of 3.M.fv from an FG6 that detects the revolution information is inputted to the clock terminal of a 1/3-dividing circuit 29, and the signal S23 is inputted to the reset terminal of the same circuit 29. The output signal S24 from the circuit 29 is inputted to a delay circuit 30, and the signal is made to be a signal S25 by the charging time constant. By setting the primary, secondary, and tertiary threshold voltages, the 1st, 2nd, and 3rd delay-circuit output signals S26, S27, and S28 are obtained. The 2nd delay time output signal S27 of the delay circuit 30 is inputted to the clock terminal of a 1/2-dividing circuit 26. At the same time, the signal S23 is inputted to the reset terminal of the same circuit 26, and a signal S29 is obtained, which is supplied from the output terminal to the phase control circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary head type magnetic recording/reproducing device, and in particular to a phase control system for rotating the rotary head in phase synchronization with a vertical synchronization signal of a video signal to be recorded. It has characteristics in its system.

2. Description of the Related Art A magnetic tape is spirally wound at a predetermined angle and run around a rotating cylinder in which a plurality of rotating heads are arranged at equal intervals, and the plurality of rotating heads are sequentially switched and used. In a helical scan type magnetic recording and reproducing device that sequentially records and reproduces one field of video signals as a recording locus inclined with respect to the longitudinal direction of the head, the configuration shown in Fig. 7 is used to further reduce the diameter of the head cylinder. is considered.

That is, in FIG. 7, reference numerals 21, 22, 23 and 24 indicate four magnetic heads A and B, respectively, arranged on the head cylinder 20 at equal intervals of 90 degrees.

A' and B, and the magnetic heads 21, 23, 22, and 24 have the same azimuth angle, respectively.

The magnetic tape 4 is wound around the head cylinder 20 over 270 degrees.

In this state, in synchronization with the rotational phase of the head cylinder, the head 21°24.23,2
2.21, recording trajectories A, B', A' are recorded on the tape as shown in FIG.

Recording trajectories of B and A are obtained.

At this time, since it is necessary to record one field of video signals on each recording trajectory A, B', A', B, it is necessary to rotate the head cylinder in synchronization with the vertical synchronization signal of the video signal to be recorded. be.

That is, it is necessary to synchronize the phase with the vertical synchronization signal and rotate the head cylinder by 3/4 during one period of the vertical synchronization signal.

For this purpose, conventionally, the output of the phase detection means 7 is set to 1 sHzi to obtain the greatest common divisor of the output of the rotational phase detection means 7 of the head cylinder 20 of 45 Hz and the vertical synchronization signal eoHz (NTSG) of the television signal to be recorded. /3 frequency divider 8 divides the frequency to 1/3 to obtain a 16Hz signal, and the total 1/4 vertical synchronization signal obtained from the television signal to be recorded.
A signal of 1 aHz frequency-divided by a frequency divider 9 to 1 aHz is phase-compared by a phase comparator 10, and the cylinder motor 11 is controlled and driven so that the phases of both signals match.

Problems to be Solved by the Invention In the above configuration, the head cylinder is phase-controlled by a 1 sHz detection signal.

In other words, the head cylinder is phase-controlled by a signal every three rotations, which is not necessarily a good problem.In order to solve the above-mentioned problems, in the case of the above-mentioned 4-head type VTR, the output of the rotational phase detector of the head cylinder is Total 2/3 frequency divided signal and vertical synchronization signal output total 1/! The phase of the frequency-divided signal is compared, and the head cylinder motor is controlled by the output so that both signals are phase-synchronized.

Operation According to the above configuration, the signal applied to the phase comparator is 2/3 of the 46Hz signal indicating the rotational phase of the head cylinder.
30 Hz, which improves control accuracy compared to the conventional 1 sHz.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a magnetic head switching signal generation circuit and a controlled signal generation circuit for a rotary head cylinder phase control circuit in a four-head magnetic recording and reproducing apparatus, which is an embodiment of the present invention, and FIG. 2 shows each component. The waveform of is shown.

In FIG. 1, magnetic heads 21 with equal azimuth angles.
A magnetic tape 4 is mounted on a rotary head cylinder 3 which is provided with magnetic heads 22 and 24 having an azimuth angle opposite to that of the magnetic heads 21 and 23 and 23 separated by an interval of 9σ.
is made to run around 270 degrees in the direction of arrow 6,
Magnetic head 21゜22.23.24 magnetic tape 4
Video signals are sequentially recorded or played back.

The signal S2□ from the PG7, which detects the rotational phase of the rotary head cylinder 3, is divided by 9 in the ⅓ frequency dividing circuit 28 to obtain a signal 523f. In addition, 3・M・fv (M is an integer, f
v is the vertical synchronization signal frequency) For example, the signal S of 1aoHz
2. is input to the clock terminal of the 1/3 frequency divider circuit 29,
The output signal S23 of the 1/3 frequency divider circuit 28 is input to the reset terminal of the 1/3 frequency divider circuit 29, and the output signal S24 of this 1/3 frequency divider circuit 29 is input to the delay circuit 30. Resistor R and capacitor C determine the delay time of
are connected in series from the power supply +VCO, one end of the capacitor C is grounded, and the signal S26 is generated due to the charging time constant.
1st. By setting the second and third threshold voltages, the first. Second. Third delay circuit output signal S26 ”2
□, obtain S28. The second delay time output signal "27" of the delay circuit 30 is input to the clock terminal of the 1/! frequency divider circuit 26, and is also input to the output signal S2 of the 1/3 frequency divider circuit 28.
3 is input to the reset terminal to obtain a signal 529fr, which is supplied to the rotary head cylinder phase control circuit from the output terminal 27, and at the time of recording, the vertical synchronization signal of the video signal to be recorded is all 1/!
The phase is compared with the frequency-divided signal, and during reproduction, the phase is compared with the reproduction reference signal to control the rotational phase of the rotary head cylinder 3.

On the other hand, the output signals S26 ``2□, S28 of the delay circuit 30
is input to the four-phase head switching signal generation circuit 31, and signals S3° and 5311S3□ are generated depending on recording and reproduction.

Obtain S33.

FIG. 3 shows a circuit diagram of an embodiment of the four-phase head switching signal generating circuit 31, FIG. 4 shows waveforms of various parts during recording, and FIG. 6 shows waveforms of various parts during reproduction. In FIG. 3, the output signals S261, S271, and S28 of the delay circuit 30 are input to the input terminals 41, 42, and 43, and the switches 44, 45 are used to output the signals S26 and S28 during recording.
is used, and only signal S27 is used during reproduction.

Reset terminal material D type flip-flop 47, 48.
49 and NOR gate 46 constitute a first four-phase ring counter, and when recording as a clock signal, the signal S2
When reproducing 8, signal S27 t' large input, reset signal is output signal S2 of 1/3 frequency divider circuit 28 from input terminal 58
Similarly, a second 4-phase ring counter is configured by the reset terminal material D type flip-flops 55, 66, 57 and the NOR gate 64, and the signal S26 is input when recording as a clock signal, and the signal S2□ is input when reproducing. Then, the reset signal is input as the signal S23. When the reset signal S23 becomes high level, all the reset terminal material D type flip-flops 47, 48, 49, 55
, 56.57 outputs are all low level, so NO
R game) 46.54 output becomes high level. Thereafter, the high level is shifted to the right according to the clock input signal, and the signals S411S4□l ``431'' 44 and the signals S45 ``461 S47'' 48 are created. O
By ORing the in-phase timing components of each 4-phase ring counter using 50°51.52.53, the overlap winding during recording is ensured.
An output signal S3°1S31.5321S33 can be generated.

Output signals S3゜, S of the 4-phase head switching signal generation circuit 31
34. S3° and S33 are input to the recording/reproducing amplifier 26, and during recording, the recording current to the magnetic heads 21, 22, 23° 24 is switched, and the winding around the rotating head cylinder 3 is performed on the running magnetic tape 4. (270°+ΔtI)
Overlap recording is performed on the magnetic tape 4 during playback.
The resistance of the delay circuit 30 so that the switching timing of the reproduction output of the spider to the positions of the magnetic heads 21, 22, 23, and 24 is delayed! -,! Adjust the head position by aligning the
The reproduction output of each head is obtained every 00.

In the above embodiment, the case of 4 heads was shown, but 6 heads were shown.
The above idea can also be applied to a method in which the magnetic tape is wound at 300° with a head, and a method in which 8 heads are used to wind the magnetic tape around a cylinder f: 3115°.When using N magnetic heads (however, N is an even number of 4 or more), and the phase can be compared with a signal obtained by dividing the rotational phase detection of the head cylinder into 1/2.Furthermore, the frequency of FQ in the embodiment shown in FIG. -1)・It is sufficient to establish it in fv.

Effects of the Invention As described above, according to the present invention, the frequency of the controlled signal supplied to the phase control circuit of the head cylinder is reduced to 1/! fv, and better phase control characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic head switching signal generation circuit and a controlled signal generation circuit for a rotary head cylinder phase control circuit in a four-head magnetic recording/reproducing apparatus, which is an embodiment of the present invention, and FIG. Waveform diagram of each part in, 3rd
The figure is a circuit diagram of one embodiment of the four-phase head switching signal generation circuit in the magnetic head switching signal generation circuit, Figure 4 is a waveform diagram of each part during recording in Figure 3, and Figure 6 is the reproduction time in Figure 3. FIG. 6 is a block diagram of the main parts of a conventional magnetic recording/reproducing apparatus. 4...magnetic tape, 6...FG, 7...
...PG. 8...1/3 frequency divider, 9...1/4 frequency divider, 10...phase comparator, 11...
Cylinder motor, 21, 22° 23.24...
Magnetic head, 26... Recording/playback amplifier, 26
...1/! Frequency divider circuit, 27...Output terminal, 28...1/3 frequency divider circuit, 29...
・1/3 frequency divider circuit, 30...delay circuit, 31・
...4-phase head switching signal generation circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 12 Figure Foil 3 Old Figure 4 Record Time Figure 5 Shitsuto Time s3

Claims (2)

[Claims] (1) A rotary head cylinder in which an even number N of magnetic heads of 4 or more with different azimuth angles are provided at intervals of 360°/N;
1-(1/N)] degree and sequentially switches the magnetic heads of the rotary head cylinder on which information is recorded and reproduced, and detects the rotational phase of a specific magnetic head among the N magnetic heads. a rotational phase detector; and a first circuit that divides the output signal of the rotational phase detector by N/(2N-2).
a frequency dividing means, a second frequency dividing means that frequency-divides the vertical synchronization signal of the recorded video signal by half, and a phase whose inputs are the first frequency dividing means output and the second frequency dividing means output. A magnetic recording/reproducing apparatus comprising: a comparator; and means for controlling the rotational phase of the rotary head cylinder so that the phases of the two signals have a predetermined phase relationship based on a phase comparison error signal of the phase comparator. (2) The first frequency dividing means divides the rotational phase detector output by 1/(
N-1) 1/(N-1) frequency dividing circuit and the rotation information of the rotating head cylinder in one rotation of M(N-1)・f
a rotation information detector that detects the frequency of __v (where M is an integer and f_v is the vertical synchronization signal frequency) as a signal; and a rotation information detector that divides the output of the rotation information detector by 1/[M(N-1)], and A 1/[M(N-1)] frequency dividing circuit that can be reset by the 1/(N-1) frequency dividing circuit output, and a 1/[M(N-1) frequency dividing circuit that can be reset by the 1/(N-1) frequency dividing circuit output.
1)] The output of the frequency dividing circuit is input, and the above 1/(N-1
2.) The magnetic recording and reproducing apparatus according to claim 1, comprising a 1/2 frequency divider circuit that can be reset by the output of the frequency divider circuit.