JPS6016776A - Rotary head type magnetic video recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent the disturbance of vertical synchronism due to a decrease in an output near a vertical synchronizing signal by forming a pseudo vertical synchronizing signal being a fixed relation of phase with a reproduced vertical synchronizing signal from a head switching pulse so as to use it as the vertical synchronizing signal. CONSTITUTION:The head switching pulse fed to an input terminal 1 is fed to the 1st differentiating circuit 2 and an inverter 4 and an output of the inverter 4 is fed to the 2nd differentiating circuit 3 and a D-FF circuit 5. The output of the D-FF circuit 5 is fed to AND gates 6-9, where pulses (f),(g),(h) and (i) phase- locked with the head switching pulse and generated sequentially at an interval of 1/2 period are obtained. These pulses are fed to the 1st and 2nd differentiating circuits 2,3 so as to close sequentially selectively switches S1-S4. As a result, a signal delayed respectively by tau1-tau4 from the switching pulse is obtained as an output of an amplifier 10, and the pseudo vertical synchronizing signal l delayed each by tau1-tau4 is obtained from a differentiating amplifier 11.

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, one field of television signals is tilted with respect to the longitudinal direction of a magnetic tape using two rotary heads having different azimuth angles.
11i1+.

Sequentially recorded on magnetic chibuto as a trace +-1j! l'\IJ )) Rusgyanka type magnetic recording and reproducing device (V
T R) t'i'.

Two μ with different azimuth angles] and fIJ, to 1
In the VTR used for the 4th edition, when the Tezo scolding was reduced to V2 at the time of recording, the scanning trajectory of the recording trajectory and the scanning trajectory of the 41-head were reduced to V2 when recording. +,',',) relationship is as shown in Figure 1. In other words, A+B in FIG.
Al+ BT+ A7+ B... is the scanning 1νL trace of A to No 1 at the time of birth] Yohi B \ Nod.

Therefore, the mountain 11 i+-j bow (7
,,) -c envelope is as shown in Fig. 2, and the endogenous output is extremely small near the local line signal17) and (-
Otherwise, it may disturb the vertical synchronization at 118.

At this time, Fig. 1 schematically shows a small 1'L tsutsu (・
Ma\Machi life trajectory A,,B,,A2. Since the head switching position (]1-scanning start position) of B2 is different from the vertical synchronization position of the tape 1, there is a difference between the head switching position and the playback vertical synchronization signal τ4.τ4.τ2. A time difference of .τ5 occurs (τ, 〈τ4〈τ3〈τ2).

And this τ4. τ1. τ2. The time difference group of τ3 is repeated as one cycle.

That is, the reproduced vertical synchronization signal is reproduced not at the same interval but at four different intervals.

In order to solve the problem that the vertical synchronization is disturbed due to the decrease in the output near the vertical synchronization signal as described above, the present invention provides a head switching pulse that has a constant phase relationship with the reproduced vertical synchronization signal having repetitive synchronization as described above. The purpose is to create a pseudo vertical synchronization signal and use it as a vertical synchronization signal. One embodiment will be described below with reference to the drawings.

In FIG. 3, the head switching pulse applied to the input terminal 1 (FIG. 4a) is applied to the first differentiating circuit 2 and the inverter 4, and the output of the inverter 2 (FIG. 4b) is applied to the second differential circuit 2 and the inverter 4. Differential circuit 3 and D-type frinozo frog circuit 6
is applied to.

The first differentiating circuit 2 includes a capacitor C4 and switches S, , S, which are opened and closed at timings described below.

The second differentiating circuit 3 includes a capacitor c2 and switches S'4 and S2 that are opened and closed at timings described below.
It is composed of resistors R4 and R2 selected by.

The output C of the Q terminal of the flip-flop circuit 5 is the first
The head switching pulse & is applied to the AND gate circuit 6 of the inverter 4 as well as the head switching pulse & of the second AND gate circuit 7.

The output d of the Q terminal of the flip-flop circuit 6 is applied to the DAM2r- of the flip-flop circuit 5.
The output of the inverter 4 is applied to the third AND gate circuit 8, and the head switching pulse a is also applied to the fourth AND gate circuit 9.

Therefore, the above-mentioned 1. Second. Each output f, g of the third and fourth AND gate circuits 6, 7, 8.9.

As shown in FIG. 4, h, 1 is synchronized with the phase of the head switching pulse AK and is generated sequentially with the A period of the head switching pulse a.

According to this output) J' + g + h + i, the switches -s, , s2 . s, , s4 are sequentially and selectively closed.

Therefore, the output terminal of the dj intensifier 1o which uses the outputs of the first and second differentiating circuits 2 and 3 as input signals has Q:1, the rise of the head switching pulse O and the rise of the output of the inverter 4 ( When the head switching pulse a falls, a differential signal e is obtained.

As shown in FIG. 4, this differential signal e is T
1. τ2. τ3. It is delayed by τ4, and this delay time is
It is determined by the combination of capacitor C4 and resistors R4 and R3, and by the combination of capacitor C2 and resistors R2 and R1.

This differential signal e is differentiated by a differential intensifier 11, and synchronized with the falling edge of the differential signal e, that is, τ4. from the rising and falling points of the head switching pulse a. τ2
．． τ3. The pseudo vertical synchronization signal e is delayed by τ4, is inserted slightly before the vertical synchronization signal of the reproduced signal m, and is used as the vertical synchronization signal.

In addition, in order to match the repetition period of the vertical synchronization signal of the pseudo vertical synchronization signal e and the reproduction signal m, the reproduction signal m and the lowest point X of the reproduction level are determined by using the output of a known dropout detection means. In addition to the set terminal S of the flip-flop 6, the seven node points of the flip-flop 6 are regulated.

That is, the mono multivibrator 13 is triggered by the head switching pulse &, and a level signal is created only in the section near the vertical synchronization signal of the endogenous signal, and this signal is used to gate the dropout detection output j. A signal k corresponding to the X point is generated by the circuit 12, and the signal k is used to operate the flip-flop 6ff to obtain a waveform as shown in FIG. 4n.

As described above, according to the present invention, since a vertical synchronization signal is created during playback and is added to the playback signal, there is no disturbance in the serial synchronization even when the playback signal level is low. There is nothing! , ), - Also, doubt 1 rigid [1) + '1
−． li', l Isuji1. 1tll (1) Since it has a certain relationship with Shu, the reproduced image (tei'iL I'L
It is something without.

4. rtR in f'ii'i of the drawing, disciple 11 so 1 schematically shows the relationship with the raw head trajectory during slow motion image reproduction. FIG. 3 is a block diagram showing an embodiment of the rotary Rad-type magnetic recording device 41 of the present invention, and FIG. 4 is a waveform diagram illustrating the same operation.

1... to /l- switching pulse input terminal, 2
゜3...Differential circuit, 4...Inverter, 6...D
Type flip-flop circuit, 6, 7, 8.9...-AND gate circuit, 10.11...... Multiplier [t], 12
...Kate circuit, 13... Mono multi.

Claims (1)

[Claims] 1 by two rotating heads with different azimuth angles at tI.
Field preview signals are sequentially recorded on the magnetic tape as recording trajectories inclined with respect to the longitudinal direction of the magnetic tape, and during playback, the tape speed is reduced to the speed of 1A during R12 recording and played back by the sub-rotary head. In a co-rotating head type magnetic recording and reproducing apparatus, the sub-rotating head during playback is synchronized with the switching pulse, and the sub-rotating head is synchronized with the switching pulse. Create four different types of signals,
A rotary head type magnetic recording beef cattle apparatus characterized in that the four kinds of signal signals are sequentially added to a reproduction signal as a vertical synchronization signal.