KR890004245B1 - Slow motion regeneration servo-system - Google Patents

Abstract

The method for reducing the variation of the phase difference of the rotating head servo system during intermittent transfer of the tape and smooth-transfering from the intermittent mode to the still mode includes a phase comparator (8) set to the operation center point of the phase comparison by a head switching signal (55) during the intermittent period, otherwise the setting operation is released. The phase comparator is composed of the binary counter and performs the set operation by pre-setting the binary counter to the count value corresponding to the operation center point of the phase comparison.

Description

Slow motion regenerative servo

1 is an operation waveform diagram of a conventional slow motion regeneration method.

2 is a conventional slow-motion recycled tape pattern.

3 is a block diagram showing the basic configuration of the slow motion reproduction servo system of the present invention.

4 is an operational waveform diagram of a main block of the present invention.

* Explanation of symbols for main parts of the drawings

1: magnetic tape 2: cylinder motor

3: frequency generator 4: speed comparison means

5: mixed circuit 6: correction circuit

7: driving circuit 8: phase comparing means

9: L.P.G. (Latch pulse generating circuit) 10: P.P.G. (Preset pulse generator circuit)

11: gate circuit 12: D.P.C. (To digital phase non-church)

13: R.S.G. (Internal reference signal generation circuit) A, B: Rotating main head

A ', B': rotating auxiliary head

The present invention relates to a slow motion reproduction servo system of a magnetic recording and reproducing apparatus which enables slow motion reproduction in a manner of repeating intermittent transfer and still reproduction.

As a slow motion reproduction method of the magnetic recording and reproducing apparatus VTR, a method of repeating intermittent transfer and still reproduction is adopted. Next, the configuration and operation of the conventional throw motion reproduction will be briefly described.

FIG. 1 shows the operation waveform diagram of the intermittent transfer in the conventional slow motion reproduction, and FIG. 2 shows the tape reproduction pattern diagram in the slow motion reproduction.

In FIG. 1, (S ₁ ) is the current waveform of the capstan motor, (S ₂ ) is the head switching signal waveform, (S ₃ ) is the intermittent command signal waveform, (S ₄ ) is the control signal waveform, (S ₅ ) Is a slow tracking signal waveform, and S ₆ is a brake signal waveform.

정속(定速)

감속의 3단계가 있으며, 그 전후의 정지기간이 스틸재생이다. 간헐이송의 기간은 대부분 2프레임(4피일드)이기 때문에, 정지기간을 임의로 설정함으로서 가변속 슬로우모우션 재생이 가능하다. 지금, 방위각 기록방식의 회전 2헤드 VTR을 예로들면, 회전 실린더사에 180

로 배열된 2개의 역방위각 헤드(A),(B)로 제 2 도에 표시한 비데오 트랙패턴을 기록형성한다.(트랙패턴은 동작을 이해하기 쉽게 하기 위하여 실제의 패턴과는 다른 모양, 테이프 길이방향에 대해서 직각으로 도시하였음) 그리고, 동일 트랙을 복수회 재생하는데 있어서는, 각각의 헤드(A),(B)에 대해서 180

위치에 같은 방위각의 보조헤드(A'),(B')를 배설하여, 주헤드와 보조헤드를 짜맞추어서 행하는 구성을 채용한다. 여기서, 슬로우모우션 재생으로는 프레임슬로우 재생과 피일드슬로우 재생의 2방법이 있고, 전자는 동작이 빠른 화상을 재생하면 기수(奇數)피일드와 우수(偶數)피일드의 시간어긋남에 의한 화상흔들림을 일으켜, 화면이 불안정하다. 이에 비해서, 후자의 피일드 슬로우에서는 기수피일드나 우수피일드의 어느 한쪽을 재생하는 구성이며, 화면이 안정하다. 제 1 도, 제 2 도는 후자의 예이다.As shown in FIG. 1, the control of the capstan motor during the intermittent transfer, that is, the tape feed is accelerated.

Constant velocity

There are three stages of deceleration, and the stopping period before and after is steel regeneration. Since the intermittent transfer period is mostly 2 frames (4 feeds), variable slow motion reproduction can be performed by arbitrarily setting the stop period. Now, for example, the rotary two-headed VTR of the azimuth recording method, the rotating cylinder yarn 180

The video track patterns shown in Fig. 2 are recorded and formed by two inverted azimuth heads A and B arranged in the same manner. (The track patterns have different shapes and tapes from the actual patterns for easy operation. Shown at right angles to the longitudinal direction) and 180 to each of the heads (A) and (B) for reproducing the same track a plurality of times.

The auxiliary heads A 'and B' having the same azimuth angle are disposed at the positions, and a configuration in which the main head and the auxiliary head are joined together is adopted. In this case, there are two methods of slow motion playback, frame slow play and feed slow play. In the former case, when a fast-moving picture is played back, the image is caused by the time shift between the odd and fine feeds. It causes shake, and the screen is unstable. On the other hand, in the latter feed slow, either the radix feed or the even feed is reproduced, and the screen is stable. 1 and 2 are examples of the latter.

이며, 화살표 방향으로 테이프가 이동하지 않는 정지시의 스틸재생 주사각은 점선과 같다. 여기서, 도면을 보기쉽게 하기 위하여 재생패턴은 주사 궤적의 중심선만을 표시하고 있다.In Fig. 2, the scanning angle during normal recording and playback is 90 degrees.

The still reproducing scanning angle at the time when the tape does not move in the direction of the arrow is the same as the dotted line. Here, in order to make the drawing easier to see, the reproduction pattern displays only the center line of the scan trajectory.

In the pause period, the recording track B is still reproduced by the main head B and the auxiliary head B ', and the "L" of the reproduction intermediate position a, that is, the head switching signal S ₂ , is reproduced by the main head B. An intermittent command signal S ₃ is generated at the midpoint a of the level period to give an acceleration command to the capstan motor. When the tape transfer starts with the acceleration command, the scan trace gradually shifts from the still regeneration trajectory to the normal regeneration trajectory, regenerating the section ab to the main head B, and the section bc to the auxiliary head B. Play with '). Then, when the acceleration period until the auxiliary head B 'regenerates near the point (C) ends, the speed servo of the capstan motor enters the constant speed control, and the reverse azimuth recording track A is normally used as the auxiliary head A'. The section cd is reproduced with a scan trajectory close to reproduction.

The tape speed in this constant speed period is set to approximately 0.8 to 0.9 times normal playback in the case of the slow slow playback. In this constant speed period, the control signal S ₄ is reproduced, the slow tracking signal S ₅ is generated to generate the brake signal S ₆ for deceleration, and the auxiliary head A 'is at the point (d). The deceleration by the brake signal S ₆ is started from the time of reproducing the vicinity, and the next recording track B is reproduced by the auxiliary head B '. When the deceleration starts, the vehicle gradually shifts to the still regeneration trajectory, regenerates the section de to the auxiliary head B ', and regenerates the section ef to the main head B. Then, when the main head B regenerates near the point f, the capstan motor is stopped and detected, the brake signal S ₆ and the intermittent command signal S ₃ are stopped, and the intermittent transfer period ends, again. It enters the regular period and performs still regeneration. Hereinafter, this operation is arbitrarily set and the same operation is repeated.

In reproducing the slow motion described above, the capstan servometer for feeding the magnetic tape and the rotary head servoometer for controlling the rotation of the rotating head are configured as follows. Capstan servos allow only speed servos, and phase servos are not possible. At this time, instead of the phase error output of the phase servo, a method of switching to the same voltage as the center voltage in operation is employed. On the other hand, the rotating head servo meter is capable of both speed servo and phase servo, so that the rotational speed is controlled so that the relative speed of the tape and the head during steel playback matches the relative speed during the total playback (or recording). Since relative speed changes, the relative speed is corrected by applying the speed servo.

At this time, if correction is applied only to the speed servo, the phase error output of the phase servo changes, resulting in a reverse correction command. Therefore, the phase of the reference signal is shifted in response to the periodic change of the head switching signal S ₂ of the rotating head. In this configuration, the phase error does not change. However, in such a phase shifting method, it is difficult to measure the period change of the head switching signal S ₂ and correct the phase of the reference signal to 1: 1, and the circuit configuration becomes complicated, so that the average fixed amount It is a simple structure which performs correction. Therefore, even if the screen shake during the intermittent transfer is reduced, the change in the phase error cannot be made zero, and the correction to the speed servo is disabled, and the phase shift correction is canceled by the transition from the intermittent transfer to the still reproduction. Synchronization of the phase servo at the time was not performed smoothly, and there was a problem that the still screen was not immediately stabilized with a transient response.

The present invention solves the conventional problems, and solves the change in the phase error of the rotational head servo phasing phase servo at the time of intermittent transfer, and also enables the slow motion regeneration to smoothly perform the transition from the intermittent transfer to still regeneration. The purpose is to provide a servo system.

The present invention is a slow motion reproducing method of repeating the intermittent transfer and still reproduction, wherein the phase comparing means of the rotating head servo-phase servo is performed by the head switching signal in at least the period including the intermittent transfer period. It sets to the operation center value of a phase comparison, and disassembles the said set operation in another period, Comprising: The said phase comparison means is comprised by the binary counter, The said binary counter is set to the counter value corresponding to the operation center value of the phase comparison. It is characterized in that the above-mentioned set operation is performed by presetting.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

의 관계로 배치하여, 회전 실린더에 대략 180°감겨서 주행되는 자기테이프(1)에 신호를 기록 또는 재생한다. (A')(B')는 주헤드(A),(B)와 같은 방위각의 보조헤드이며, 주헤드에 대해서 거의 180

위치에 배치되어, 슬로우모우션 재생에 주헤드와 협동해서 사용되어진다. (2)는 회전실린더를 회전구동하는 실린더 전동기, (3)은 실린더 전동기(2)의 회전수를 검출하는 주파수 발전기(FG), (4)는 주파수발전기(3)에서 검출한 주파수발전기신호(S₁)로부터 속도오차 (S₂)를 검출하는 속도비교수단, (5)는 속도오차 (S₂)와 위상오차 (S₇)를 혼합하는 혼합회로, (6)은 혼합회로(5)의 출력 (S₃)과 간헐 지령신호 (S₄)를 입력으로하여, 간헐이송 기간의 상대속도를 보정하는 보정회로, (7)은 보정회로(6)의 출력을 입력으로 하여, 실린더전동기(2)를 구동하는 구동회로이며, (3)~(7)로 속도 서어보를 구성한다. (8)은 위상비교수단이며, 위상오차출력 (S₇)을 속도 서어보의 혼합회로(5)에 입력하여, 위상서어보를 구성한다. 위상비교수단(8)은 디지탈회로로 구성하고, 그 구성요소는 래치펄스 발생회로(L.P.G)(9), 프리세트펄스 발생회로(P.P.G)(10), 게이트회로(11), 디지탈 위상비교회로(D.P.C)(12), 내부 기준신호 발생회로(R.S.G)(13)이다.3 shows an embodiment of the slow motion reproduction servo system of the present invention. (A) and (B) are main heads with different azimuth angles, and 180 ° on the rotating cylinder

In this relationship, the signal is recorded or reproduced on the magnetic tape 1 which is wound around 180 ° around the rotating cylinder. (A ') (B') is an auxiliary head of the same azimuth angle as the main heads (A) and (B), and is approximately 180 with respect to the main head.

It is placed in position and used in coordination with the main head for slow motion regeneration. (2) is a cylinder motor for rotating the rotary cylinder, (3) is a frequency generator (FG) for detecting the number of revolutions of the cylinder motor (2), (4) is a frequency generator signal detected by the frequency generator ( Speed comparing means for detecting a speed error S ₂ from S ₁ , (5) a mixing circuit for mixing a speed error S ₂ and a phase error S ₇ , and 6 a mixing circuit 5 for A correction circuit for correcting the relative speed of the intermittent transfer period by inputting the output S ₃ and the intermittent command signal S ₄ , and the cylinder motor 2 using the output of the correction circuit 6 as an input. ) Is a drive circuit for driving), and constitutes a speed servo with (3) to (7). Reference numeral 8 denotes a phase comparing means, which inputs a phase error output S ₇ to the mixing circuit 5 of the speed servo to form a phase servo. The phase comparison means 8 is composed of a digital circuit, the component of which is a latch pulse generation circuit (LPG) 9, a preset pulse generation circuit (PPG) 10, a gate circuit 11, and a digital phase comparison circuit. (DPC) 12 and internal reference signal generation circuit (RSG) 13.

In the above configuration, both the speed servo and the phase servo at the time of slow motion reproduction are set so that the relative speed at the time of still reproduction is approximately equal to the relative speed at the normal recording or reproduction, and the intermittent command signal (S ₄ at the time of intermittent transfer). The correction circuit 6 is operated to adjust the speed servo so that the relative speed does not change. On the other hand, the phase comparison means 8 is set to the operation center value of the phase comparison so that the phase error S ₇ does not change and the reverse speed is not applied to the speed servo. When the intermittent transfer is completed, the set operation is released. It is assumed that the configuration. When the intermittent transfer ends, the speed servo correction circuit 6 also cancels the correction operation. By repeating the above operation during slow motion playback, stable slow motion playback is enabled.

This invention makes novel the phase comparison means 8 of such a phase servo. Next, the configuration and operation of the phase comparison means 8, which is the main block of the present invention, will be described with reference to the waveform diagram of FIG.

In the LPG 9, the head switching signal S ₅ for selectively switching the regeneration outputs of the rotation heads A, A, A ', and B' obtained by the detection of the rotation of the rotating cylinder to be pulled out, The clock pulse S ₆ and the intermittent command signal S ₄ are inputted, and are generated in advance of the latch pulse S _{8 in} timing, and the intermittent command signal S ₄ is generated. The set clock (S ₉ ) and clock pulse (S ₆ ) are created with a prohibited clock (S ₁₀ ) forbidden during the latch operation. In the PPG 10, the clock pulse S ₆ and the internal reference signal S ₁₃ of the RSG ₁₃ are input to generate a preset pulse S ₁₁ . Gate circuit 11. The input to the pre-set pulse (S ₁₁₎ of the pre-set pulse (S ₉₎ PPG (10) of the LPG (9), to obtain a logical sum (OR) output (S _12). In the DPC 12, a latch pulse S ₈ , a preset pulse S ₉ , and a prohibition clock S ₁₀ are input. In the normal phase comparison operation, the equivalent ladder waveform shown in FIG. 4 (S ₁₄ ) is preset by initializing the initial value NP of the coefficient with a preset pulse S ₁₁ to the binary counter constituting the DPC 12. Digitally form the signal. Then, the ladder pulse wave signal S ₁₄ is sampled, ie latched, by the latch pulse S ₈ to compare the phases, thereby obtaining a phase error S ₇ . Here, (T1) of the ladder wave (S ₁₄ ) is the first half period, (T2) is the second half period, and the steady state phase locked.

Now, if (T2) is set to a fixed value and (T1) can be arbitrarily set by switching the NP, it is possible to match the relative speed during still playback with the relative speed during normal recording or playback. In other words, the internal reference signal S ₁₃ decodes the count output of the DPC 12 to the RSG 13 to generate a pulse at the end of the second half period T2. Preset pulse S ₁₁ is created, NP is preset, and the Perurp is formed so that (T1) and (T2) are repeated again.

In still playback, the period of the head switching signal S ₅ coincides with one cycle (T1 + T2) of the internal reference signal S ₁₃ , but during intermittent transfer, the speed servo is corrected to correct the relative speed. Since the period of the head switching signal S ₅ does not coincide with (T1 + T2), the sampling position is separated from the inclination center position of the ladder wave signal S ₁₄ , that is, the center of operation, and the phase error S ₇ . Changes.

Therefore, in the present invention, the intermittent transfer period is configured to preset the count value NC with respect to the operation center value of the phase comparison by the preset pulse S ₉ generated by the head switching signal S ₅ . The position error S ₇ does not change during this time, and the value of the center of motion is eliminated, thereby eliminating the inverse correction of the speed servo, and at the same time, smoothing the transition from steel regeneration to intermittent feed.

After the intermittent transfer, the preset operation of the count value NC is canceled, and the preset operation at the time of still reproduction is reproduced to smooth the transition from the intermittent transfer to still reproduction.

As described above, in the present invention, the phase comparison means 8 is set (preset to the coefficient value NC) in accordance with the intermittent transfer period and the head switching signal S ₅ at the operation center value of the phase comparison. The period (steel regeneration period) is a configuration in which the set operation is canceled. The reverse correction of the speed servo by the phase servo can be eliminated, and the transition from intermittent transfer to still regeneration (still regeneration to intermittent transfer) Since the transition can be extremely smooth, the confusion of the phase servo can be prevented.

In addition, the set operation described above may be a period including an intermittent feed, and may be performed immediately after the transition from the intermittent feed to still regeneration, and of course, if the speed servo is sufficient, all the periods of slow motion regeneration may be performed. .

The phase comparison means 8 is not limited to the configuration of FIG. 3, but has a set function for setting an operation center coefficient value NC having a higher priority than a preset for presetting the initial value NP. In this case, the preset value switching of the (NP) and (NC) in the DPC 12 and the gate circuit 11 can be eliminated.

It goes without saying that the modified configuration of the preset function can also be applied.

In addition, the present invention can be applied to the phase servo of the capstan servo, and the speed servo can be stably operated by performing the operation center set operation over the entire period of slow motion regeneration.

As apparent from the above description, in the present invention, in the period including intermittent transfer during slow motion regeneration, the phase comparison means of the rotation head servo phase shifter is set to the operation center of phase comparison by the head switching signal. Since the set operation is canceled in another period, the reverse correction to the speed servo can be eliminated, and the transition from the intermittent feed to the steel regeneration and the still regeneration to the intermittent feed can be smoothly performed. Motion reproduction can be enabled, and the practical effect is large.

Claims (2)

In the slow motion reproducing state in which the intermittent transfer and the still regeneration are repeated, in the period including at least the intermittent transfer period, the phase comparing means 8 of the rotating head servo-phase servo is performed by the head switching signal S ₅ . The slow motion regeneration servo system is set to the operation center value of the phase comparison, and the set operation is canceled in another period. The slow mower according to claim 1, characterized in that the phase comparison means (8) is constituted by a binary counter to perform the set operation by presetting the binary counter to a counter value corresponding to the operating core of the phase comparison. Sean regenerative servo. In the slow motion reproducing state in which the intermittent transfer and still reproduction are repeated, in the period including at least the intermittent transfer period, the phase comparing means 8 of the rotating head servo-phase servo is performed by the head switching signal S ₅ . Phase comparison means (8) of the capstan servomotor phase servo set by the rotation detection signal of the capstan motor during the period of slow motion regeneration while the set operation is canceled in the other period. ) Is set in the center of motion of the phase comparison.

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