JPS6194472A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To control the rotary phase of a capstan motor by reproducing a control signal by means of a control head at reproduction and comparing the reproduced signal with a reproduction reference signal in phase by duty changing information at recording. CONSTITUTION:A reproduction control signal S9 of an input terminal 42 is waveform-shaped by amplifiers 43 and 44 to obtain signals S11 and S12. They are inputted to an FF45 to go to signals S13, and further inputted to a terminal R of a counter through an inverter 46. A capstan FG signal from an input terminal 41 is inputted to a clock terminal CL. An output signal S15 of a counter 47 is displayed in an analog form to go to a triangular wave, and varies in accordance with the duty of a reproduction CTL. Its intermediate value is inputted to a 1/2 FF48 and the signal S11 is inputted the terminal CL of said FF48, thereby obtaining a signal S10. When the signal S10 is inputted to a phase control circuit, a reproduction control signal rotates the capstan motor so that its phase can synchronize with that of a reproduction phase reference frequency signal. Thus jitters of a horizontal synchronizing signal of a reproduction image can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to magnetic recording and reproducing devices such as video tape recorders.

Conventional Structure and Problems Therein FIG. 1 shows a block diagram of a servo circuit in a conventional two-head type magnetic recording/reproducing apparatus.

In Figure 1, two magnetic heads with different azimuth angles are attached at 180° intervals. Rotational phase detection detects the rotational phase of a 7-cylinder motor Q with a sunda (not shown) directly connected to its shaft. The output of the generator (hereinafter referred to as PG) 9 is input to the phase control circuit 6. Input terminal 1 when recording
The vertical synchronizing signal in the input recording video signal is input to the phase control circuit 6 via the L frequency divider circuit 3 and the switch 5, and is compared in phase with the output of the PG 9, and is input to the drive circuit 7. The output of the frequency generator (hereinafter referred to as FG) 11 that detects the cylinder motor 100 rotation information is input to the speed control circuit 8, and the output is input to the drive circuit 7, so that the cylinder motor 0 is recorded. The magnetic tape (
(not shown), video signals are recorded using a magnetic head. At the same time, the signal obtained by dividing the frequency of the vertical synchronization signal by 1 is recorded at C and T.
, the L amplifier 12 and the switch 13, and are recorded on the magnetic tape by the control head 14.

On the other hand, in the capstan motor 25 that transports the magnetic tape, the output of the FG 24 that detects rotation information is input to the speed control circuit 22 and the FG frequency dividing circuit 21, and during recording, the FG
The output of the frequency dividing circuit 21 is inputted to the phase control circuit 20 via the switch 19, and the recording capstan phase reference frequency signal obtained by dividing the clock signal from the input terminal 2 by the frequency dividing circuit 17 is inputted via the switch 18. It is input to the phase control circuit 2.0 and compared in phase with the output of the FG frequency dividing circuit 21,
The outputs of the phase control circuit 2o and the speed control circuit 22 are input to the drive path 23, and the capstan motor 25 transports the magnetic tape at a predetermined speed.

During reproduction, the cylinder motor 10 is in phase synchronization with the reproduction phase reference frequency signal obtained by dividing the clock signal from the input terminal 2 by the frequency dividing circuit 4 and inputting it to the phase control circuit 6 via the switch 5. The capstan motor 25 rotates, and the control signal recorded on the magnetic tape is reproduced by the control head 14 and amplified by the reproduction C, T, L amplifier 15 via the switch 13.
9 to the phase control circuit 20, and the reproduced phase reference frequency signal is input to the phase control circuit 20 via the tracking circuit 16 and switch 18, so that the reproduced control signal is phase-synchronized with the reproduced phase reference frequency signal. Rotate. Therefore, the regeneration phase is transferred to the cylinder via the reference frequency signal (the cylinder and the regeneration condenser).

- Since the signal signals are phase-synchronized, a reproduced image can be obtained.

The conventional two-head rotating magnetic recording/playback device described above is capable of continuously recording and playing back video signals, but the diameter of the rotating head cylinder becomes large, so it has the disadvantage that it is not suitable for making the device smaller and lighter. .

OBJECTS OF THE INVENTION The present invention aims to provide a four-head type magnetic recording/reproducing apparatus which solves the above-mentioned conventional problems.

Structure of the Invention The present invention divides the PG multiplied signal of the Radon cylinder into rotation by 1,
When recording, the vertical synchronization signal of the recorded video signal is divided by 1,
The rotational phase of the rotary head cylinder is controlled by comparing the phase with the PGO1 frequency-divided output, and the vertical synchronization signal of the recorded video signal is frequency-divided by 1, and the control head is sent to the control head by 1.
Recording is performed by changing the duty of the recording control signal every other time, and during reproduction, the 1 frequency division output of the PG and the reproduction reference signal are phase-compared, the rotational phase of the rotary head cylinder is controlled, and the magnetic tape is The recorded control signal is reproduced by a control head, and only one of the two reproduction control signals is adopted according to the duty change information at the time of recording, the phase is compared with the reproduction reference signal, and the magnetic tape is transferred. It is equipped with servo means for controlling the rotational phase of the capstan motor.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows a block diagram of a servo circuit in a four-head magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 3 shows signal waveforms at various parts.

In Figure 2, four magnetic heads with alternating azimuth angles are attached at 900-degree intervals, and a magnetic tape is wound and run at an angle of 27o0 on a cylinder (not shown).
The output signal S1 of the PGs, which detects the rotational phase of the cylinder motor o directly connected to the shaft thereof, is input to the j frequency divider circuit 33, and its output signal S2 is input to the phase control circuit 6.

During recording, the output signal S4 of the recorded video signal inputted from the input terminal 1 is inputted to the Σ frequency dividing circuit 31 to obtain an output signal S5, which is inputted to the phase control circuit 6 via the switch 5. The phase is compared with the output signal S2 of the i frequency dividing circuit 33 and input to the drive circuit 7, and the output of the FGll that detects the rotation information of the cylinder motor o is input to the speed control circuit 8, and the output is input to the drive circuit 7. By inputting it to the circuit 7, the cylinder motor o is phase-synchronized with the vertical synchronization signal during recording, and the magnetic spatula path 3 is applied to the magnetic tape.
The output signal S4 of Σ and the output signal S5 of the Σ frequency dividing circuit 31 are input to the recording C, T signal processing circuit 32 to obtain an output signal S6, which is recorded on the magnetic tape by the control head 14 via the switch 13.

On the other hand, the output of the FG 24 that detects the rotation information of the capstan motor 25 that transports the magnetic tape is input to the speed control circuit 22, the FG frequency dividing circuit 21, and the reproduction C, T, and L processing circuit 34. The output of the circuit 21 is input to the phase control circuit 2o via the switch 19,
The recording capstan phase reference frequency signal obtained by dividing the clock signal from the input terminal 2 by the frequency dividing circuit 17 is sent to the switch 1.
8 to the phase control circuit 2Q, the phase is compared with the output of the FG4 circuit 2o, and the phase X++ control circuit 20
The output of the speed control circuit 22 is input to the drive circuit 23, and the capstan motor 25 transports the magnetic tape at a predetermined speed.

During reproduction, the cylinder motor 1Q is phase-synchronized with the reproduction phase reference frequency signal S7 obtained by dividing the clock signal from the input terminal 2 by the frequency dividing circuit 4, which is input to the phase control circuit 6 via the switch 5. and rotate. The control signal recorded on the magnetic tape is the control signal.
-14 Te playback signal S9 is obtained, and the playback signal S9 and the output of capstan FG24 are sent to the playback C, T, L processing circuit 34.
is input.

A circuit block diagram of one embodiment of the reproduction C, T, L processing circuit 34 is shown in FIG. 4, and waveforms of each part are shown in FIG. 6.

In FIG. 4, the reproduction control signal S9 at the input terminal 42 is input to a positive direction pulse amplifier 43 and a negative direction pulse amplifier 44, where the waveforms are shaped and the signal S11
．． S12 is obtained, both are input to the R,5F-F (flip-flop) circuit 46 to obtain the signal S13, and the signal "13 is inputted to the reset terminal of the counter circuit 47 via the innocuous circuit 46 and clocked. A capstan FG signal (not shown) from the input terminal 41 is input to the terminal.When the contents of the counter of the counter circuit 47 are displayed in analog form, the signal S14 shows a triangular waveform 9, reproduction C, T, L. The output signal S of the counter circuit 47 changes depending on the duty of the signal.
15 is obtained and inputted to the set terminal of the ΣF, F circuit 48, and the output signal S11 of the positive direction cross amplifier 43 is inputted to its clock input terminal, thereby obtaining the output signal S1o of the LF, F circuit 48 and outputting it. Output from terminal 49.

The output signal S1o of the reproduction C, T, L processing circuit 34 is inputted to the phase control circuit 20 via the switch 19, and the reproduction phase reference frequency signal S7 is input to the tracking circuit 16 as a signal S8.
Then, the reproduction control signal is input to the phase control circuit 20 via the switch 18, and the capstan motor 26 rotates so that the reproduction control signal is phase-synchronized with the reproduction phase reference frequency signal. Therefore, the cylinder and the reproduction control signal are phase-synchronized via the reproduction phase reference frequency signal, so that a reproduced image can be obtained.

Effects of the Invention According to the present invention, it is possible to provide a servo means with less fluctuation (jitter) in a horizontal synchronization signal of a reproduced image during self-recording and reproduction of a four-head type exhaust recording and reproduction apparatus. Further, compatibility between the four-head type exhaust recording/playback device and the conventional two-head type exhaust recording/playback device can also be maintained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a servo circuit in a conventional two-head magnetic recording/playback device, FIG. 2 is a block diagram of a servo circuit in a four-head magnetic recording/playback device according to an embodiment of the present invention, and FIG. FIG. 2 is a signal waveform diagram of each part in FIG. 2, FIG. 4 is a circuit block diagram of an embodiment of a reproduction C, T, and L processing circuit that can be used in the present invention, and FIG. 6 is a signal waveform diagram of each part in FIG. It is. 1.2...Input terminal, 3...1 frequency divider circuit,
4.17... Frequency divider circuit, 5,13,18.19.
...Switch, 6,20...Phase control circuit, 7.23 ...Drive circuit, 8,22...
...Speed control circuit, 9...PGllo...
... Cylinder motor, 11.24...FG, 1
2... Record C, T, L amplifier, 14...
C, T, L head, 15... Reproduction C, T, L amplifier, 16... Tracking circuit, 21...
FG frequency divider circuit, 26...Capstan motor, 31...1 frequency divider circuit, 32...Record C
, T, L processing circuit, 33. -0-・-frequency divider circuit, 34・
...Reproduction C, -T, L processing circuit.

Claims (2)

[Claims] (1) Alternately rotate magnetic heads with different azimuth angles at 90°
A rotary head cylinder provided at intervals, a magnetic tape recorded by the magnetic head of the rotary magnetic head, a rotary phase detector for detecting the rotational phase of the magnetic head, and an output of the rotary phase detector. 1 to divide by 1/3
/3 frequency divider circuit, during recording, divides the vertical synchronization signal of the recorded video signal by 1/4, compares the phase with the output of the 1/3 frequency divider circuit, controls the rotational phase of the rotary head cylinder, and controls the rotational phase of the rotary head cylinder. The vertical synchronization signal of the recorded video signal is frequency-divided by 1/2, the duty of the recording control signal is changed every other time by the control head, and the duty of the recording control signal is changed every other time, and during reproduction, the output of the 1/3 frequency dividing circuit and the reproduction reference signal are used. Compare the phase,
In addition to controlling the rotational phase of the rotary head cylinder, the control signal recorded on the magnetic tape is reproduced from the control head, and only one of the two reproduction control signals is adopted based on duty change information at the time of recording. , a magnetic recording and reproducing apparatus comprising servo means for comparing the phase with the reproduction reference signal and controlling the rotational phase of a capstan motor for transporting the magnetic tape. (2) The magnetic recording and reproducing apparatus according to claim 1, wherein the duty of the reproduction control signal is determined by using the output of a rotation information detector of the capstan motor as a clock. .