JPS60251552A - Recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent disturbance in a reproduced picture before and after an editing point, by inversionally controlling the phase of frequency-halved signals thereafter, when the phase relation of a head rotating signal to a field signal generated from the synchronizing signal of input video signals, is not in a previously fixed condition. CONSTITUTION:Input video signals are supplied to an H synchronizing separator 6, and an H synchronizing signal A is supplied to monostable multivibrators (MMV) 12 and 13. And the output C of the multivibrator 13 is supplied to a gate 15. At the same time, the signal A is also supplied to a V synchronizing separator 7 and a V synchronizing signal D is supplied to the other input of the gate 15 after the signal D is changed to an output E by an MMV14. The output pulse F of the gate 15 is generated at the even field of the input video signals. Upon receiving a drum locking signal, a gate 17 is opened and the output of a gate 16 indicating the phasic relation between the signal F and an SWP signal G is supplied to an MMV18. The MMV18 outputs a pulse H or J and inverts the phase of the frequency dividing output I or K of an FF8 thereafter. Therefore, disturbance in reproduced pictures before and after an editing point can be prevented.

Description

TECHNICAL FIELD The present invention relates to a recording and reproducing apparatus, and more particularly to a two-head helical scanning type recording and reproducing apparatus that records and reproduces information by helically scanning a recording medium with two rotary heads.

BACKGROUND TECHNOLOGY In VTRs (video tape recorders) for broadcasting or business use, the head is rotated so that the continuity of the field of the recorded video signal is maintained before and after editing points such as assembly editing and insert editing. The drum phase is controlled so that it has a constant relationship with the field phase of the input video signal. However, in consumer VTRs such as home use, the continuity of the field before and after the editing point is The current situation is that it is ignored. That is, when a VTReTR is used as a top load, there is no unambiguous relationship between the phase of the rotating drum and the field phase of the input video signal. For example, in a two-head VTR, one head does not necessarily record an even field signal.

FIG. 1 is a block diagram showing a part of the drum servo of a conventional two-head consumer VTR.
A pulse signal corresponding to the rotation of is amplified by an amplifier 2 and supplied to a delay device 3. The signal whose phase has been adjusted by the delay device 3 is waveform-shaped by the FF (free lag flop) 4 to form a 5W signal with a duty of 50 chips and a period of 1 frame.
P (switching pulse). This SwP is used as a head switching signal for a reproduction signal or a recording signal, and is inputted to a trapezoidal wave generator 5 to generate a trapezoidal wave.

On the other hand, the input video signal is H (horizontal) sync and ■ (vertical)
Each synchronization signal is separated by synchronization separators 6 and 7, and (2) the frequency of the synchronization signal is divided by two by an FF8. This frequency-divided signal is transmitted to the delay device 9
It undergoes phase adjustment and becomes an input to the sample pulse generator 10. Therefore, sample pulses can be generated that are synchronized with the 2-frequency divided signal of the V synchronization signal of the input video signal.
This sample pulse causes the level of the slope part of the output of the trapezoidal wave generator 5 to change to the S/H (sample/hold) circuit 1.
You can sample at 1. This sample hold output indicates the drum phase error, and by doing so, the rotation control of the rotating drum motor 1 is performed. A phase comparison is performed. Here, since the frequency division by two is performed regardless of whether the field is even or odd, the relationship between the output phase of FF8 and the even or odd field of the video signal is not uniquely determined, and therefore the drum rotation phase and Even number of fields.

The relationship with odd numbers is also uncertain. This indicates that the continuity of the field before and after the editing point may not be maintained, and therefore, when this editing tape is played back, the playback monitor image may be momentarily disturbed at the editing point. become.

Summary of the Invention The present invention provides a two-head helical scanning type recording and reproducing device that prevents disturbances in reproduced images by maintaining continuity of fields before and after an edit point when performing assemble editing or insert editing. is intended to provide.

The recording/reproducing apparatus according to the present invention is obtained by dividing the head rotation signal obtained by the rotation of the rotary head and the vertical synchronization signal of the input signal to be recorded by two.

The target is a two-head type recording and reproducing device that controls the rotation of the rotary head by comparing the phase of the input video signal with the divided-by-half signal. means for generating a field signal indicative of one of the fields, and determining the phase relationship of the head rotation signal with respect to the field signal, and subsequently inverting the phase of the frequency-divided signal by two if the phase relationship is not in a predetermined state; and controlling means.

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

FIG. 2 is a block diagram of an embodiment of the present invention, and parts equivalent to those in FIG. 1 are indicated by the same symbols.

In the figure, the H synchronization signal A separated from the input video signal by the H synchronization separator 6 is the trigger input of the MMV (Mono Staple Multi-Vibe) 12.
This MMV12 is a trigger.

11. While the pulse output is being generated, a new trigger is generated.
, the width of the pulse output is approximately (3/4)H, and it is an MMV for horizontal equalization pulse removal.

The output B of the MM'V12 serves as a triggering force for the MMV13, which generates an output with an extremely small pulse width, and outputs a constant pulse train C synchronized with the generation timing of the synchronization signal.

On the other hand, the V synchronization signal from the synchronization separator 7 is generated with a delay of 0.75H relative to the V synchronization of the input A. Therefore, the circuit constants of the V synchronization separator 7 are selected accordingly. There is. The MMV 14 is triggered by this V synchronization signal and a pulse E having a width of 0.5H is obtained. This pulse E and the previous MMV1
The output C of 3 becomes the two inputs of the AND gate 15, and this gate output F is gated by the AND gate 16 in response to the SwP signal (see FIG. 1). This gate output is further gated by an AND gate 17 in response to a drum lock signal (a signal generated when the servo of a drum servo system (not shown) is locked), and becomes a trigger input for MMV18. The output H (or J) of this MMV18 becomes the other input of the AND gate 19 which inputs the synchronization signal Dil, and the output of this gate 19 becomes an FF that divides the frequency of the synchronization signal by two.
8 trigger signal. The output of this FF8 ■ (or K)
is input to the sample pulse generator 10 through 9 delay devices and becomes 1
, resulting in the sample pulse shown in FIG.

FIG. 3 is a time chart showing the operation of the block in FIG. 2, and (Al- indicates the waveforms of signals (5) to ■ in the block in FIG. 2, respectively. Input video signal Using the synchronization signal A included in the synchronization signal A, an H synchronization signal train with a pulse width of several microseconds from which the equalization pulse has been removed is obtained as shown in C. On the other hand, the delay time for the input A of the synchronization separator 7 is 0. The circuit constant of the separator 7 is determined to be an odd multiple of 25H, and in this example, 3x0.25 =
Assume that it is 0.75H. Note that this tolerance value is ±025H. Due to the rise of this signal, MM
When Vl4 is triggered, a signal having a pulse width of approximately (1/2) H is obtained as shown in E.

If we pay attention to the signal waveforms of C and E, which are the two manual inputs of 15, they match in even fields and do not match in odd fields. This is 1/25 of the V synchronization signal period for interlace processing.
This is because 2.5 is the H synchronization signal period. Here, ■If you change the circuit constants of the synchronous separator 7, the signals C and E
A field that matches can be considered an odd field.

In this example, a coincidence pulse (output of the gate 15) is generated in an even field as shown in F.

This pulse F is a field signal indicating the field phase of the input video signal. The purpose of the present invention is to use this field signal to determine the rotational phase of the rotary drum and determine this rotational phase, and this is carried out by the circuits after gate 15.

That is, since the phase of the rotating drum can be determined from the SwP signal, the phase relationship between this SwP signal image and the field signal F is determined by the gate 16. S with frame period (30Hz)
Depending on whether the wP signal image shift field signal F is gated or not, it is possible to determine whether the field phase of the input video signal and the drum rotation phase match or do not match.

Here, the drum motor is started in response to the recording command, and the frequency of the synchronizing signal is divided by two to generate an f30Hz pulse [When the SWP signal is synchronized, the phase of this frequency-divided by two signal is equal to As described in the prior art, the fields recorded by the two heads are not fixed in size.

Therefore, the circuit shown in Fig. 2 should be activated after starting the motor and determining whether it is synchronized with the field of force j or the resultant force j. Therefore, when the drum lock signal is received, Gate 17 is opened, and the output of gate 16 indicating the phase relationship between signals F and G is output from the MMV of the next stage.
It has been introduced into 8.

Now, for example, if the phase relationship in an even field at the SwP signal image level is a normal relationship, the relationship between tel and C1 in the time chart in Figure 3 is incorrect, so at this time The signal F can be introduced into the trigger input of ■■18.

Therefore, MMVl8 outputs pulse H (or J),
The phase of the frequency division ratio K (or K) of FF8 is then inverted. The method includes (1) detecting the reverse phase state and
Next to the V synchronization signal, one or an odd number of synchronization signals are gate 1.
(2) Detect the reverse phase state and generate it from the pseudo pulse JThMMV18 for inversion control via the AND gate 19 at the generation timing of the iV synchronization signal. Dese,
There are two things that will cause the output of FF8 to be inverted from now on.

Both (1) and (2) use the circuit shown in FIG. 2 to make the most of their use, but only the setting of the output pulse width of MMV18 is different. In method (1), and
for a sufficient period of time (2
A pulse H'kMMV 18 of about 0 ms) is generated. Then, FF8 for frequency division by 2 prevents inversion by one synchronization signal, so FF8 for field phase
The output phase of is reversed, and the SWP output as shown in FIG. 3 (■') is obtained, and a normal phase relationship is obtained.

In method (2), the output J of the MMV 18 is made sufficiently shorter than the pulse width of the synchronizing signal (for example, about IH).

Then, the output of FF8 will be inverted by the fall of the output J of MMV18, so the purpose will be achieved.0 In method (1), an odd number of V synchronization signals including one are blocked, and '! It is clear that in the method (2) of I8, an odd number of pseudo pulses including one pseudo pulse may be generated within the pulse period of the synchronizing signal.

In this way, by matching the output phase of FF8 to the Kefield phase, the head phase matches the field phase. [Bad drum phase servo is performed by the difference between the output phase of FF8 and the SwP signal phase as shown in Figure 1, so if the phase inversion process shown in Figure 2 is performed when synchronization is first performed, , FF8 is inverted controlled, so
The servo becomes unsynchronized and a phase error occurs, and the drum phase (SwP) is stabilized by correct control.

Effects of the Invention As shown above, according to the present invention, the rotational phase of the head rotating drum can be made to match the field phase of the recorded video signal, so that the playback image quality before and after editing such as splice recording and inserts is improved. There are advantages. Furthermore, although the conventional circuit shown in FIG. 1 is integrated (IC), when the circuit of the present invention is applied to the IC circuit shown in FIG. Gate signal generator for 19 (MMV12.13.14.

18, gates 15 to 17, etc.).

[Brief explanation of the drawing]

Figure 1 is a partial block diagram of a conventional drum servo system, Figure 2
The figure is a block diagram of an embodiment of the present invention, and FIG. 3 is a time chart showing the operation of the blocks in FIG. 2. Explanation of symbols of main parts 1...Drum motor 6...H synchronous separator 7...
■Synchronous separator 8...FF12-14 for frequency division by 2, 1
8-MMV 15-i7, 19-7;/Dogate Applicant Pioneer Corporation Agent Patent Attorney Motohiko Fujimura

Claims (1)

[Claims] The rotation of the rotary head is controlled by comparing the phases of a head rotation signal obtained by processing the rotation of the rotary head and a frequency-divided signal obtained by dividing the vertical synchronization signal of the input video signal to be recorded by two. A two-head type recording/reproducing apparatus comprising means for generating a field signal indicating one of odd and even fields from a synchronization signal of the input video signal, and a head rotation signal corresponding to the field signal. 2. A recording/reproducing apparatus comprising means for determining a phase relationship between the two and controlling the phase of the frequency-divided signal to be subsequently inverted when this phase relationship is not in a predetermined state.