JPH01105348A - Linking recording control circuit for helical scanning tape device - Google Patents

Abstract

PURPOSE:To reproduce a linking-recorded part without any trouble by obtaining the phase control signal of a capstan motor trailing a tracking error signal during a reproducing action. CONSTITUTION:A time difference n=a-c between a capstan control signal (a) and a capstan rotation detecting pulse (c) is sent to a subtracter 31 through a latch 23 during the reproducing action. On the other hand, a counter 22 D/A- converts 26 a counted value (d) of the signal (a), voltage-compares 27 an output (d') with the tracking error signal, sends a signal (f), whose output is supplied to a mono-multi 28 and inverted, and an output signal (g) from the latch 30 is given to a subtracter 31. Here, the subtracter 31 subtracts a value (m) of the signal (g) from the value (n), sends it through a latch 32 to a comparator 33, here it is compared with the counter output (d), and a signal (i) is taken off through a mono-multi 34. The signal (i) delays a reference signal by the time, in which the output in the phase comparison of the capstan motor subtracts the phase difference to be equal with the tracking error signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improving the continuity during splicing of a track following type helical scan magnetic tape storage device having a tracking control signal on an inclined track.

[Conventional technology]

As is well known, the tracking control methods of health-based scan tape devices include those using control tracks such as the VH8 method and β method, and those using frequency multiplexing on inclined tracks such as 8mm and DAT (digital audio tape recorders). Alternatively, the automatic track following method (ATF) divides the area and records the tracking control signal.
). The rotation control of the rotary cylinder motor that carries the magnetic head and the capstan motor that drives the tape is carried out by controlling the speed of the rotary head so that it rotates at a predetermined number of rotations, and the recording video signal during recording. During playback, phase control is performed to synchronize the phase with the vertical synchronization signal of the tape and with a reference oscillator having a frame frequency.The capstan motor has speed control to run the tape at a predetermined speed. During recording, the rotation of the capstan is synchronized in phase with the reference oscillator to improve the accuracy of the tape feed speed, and during playback, the capstan is controlled so that the magnetic head accurately tracks the recording trajectory. The control pulse reproduced by the head is phase-synchronized with the reference oscillator, and in the ATF method, the capstan motor is controlled by a tracking error signal.

When attempting to continue recording on a part that has already been recorded, the control of the capstan motor that drives the tape is switched, which causes disturbances in the control signal at the time of switching, causing fluctuations in the tape running speed. As described in Japanese Patent Publication No. 57-39460 and Japanese Patent Application Laid-Open No. 60-201562, in order to maintain continuity and record continuously, the phase of the playback control signal is and the phase of the detection pulse signal synchronized with the rotation of the capstan are made to match in advance.

[Problem that the invention seeks to solve]

These are related to the control track method, and the ATF method is not mentioned. A.T.
In the F method, the capstan speed is controlled to be the same during recording and playback.

However, since the phase relationship between the capstan rotation detection pulse signal and the reference signal during playback is unstable, the phase difference signal generated when switching from playback to recording becomes meaningless and must be stabilized. It takes about 1 second to complete,
During this period, the recording track pitch was also severely disturbed. An object of the present invention is to provide a means for solving the above-mentioned problems with the ATF method, and to reduce discontinuity in the recording track pitch even when continuous recording is performed, so that there is no tracking error in the continuous recorded portion during playback. The purpose is to provide a control circuit.

[Means for solving problems]

The above purpose is to perform a playback operation prior to continuous recording, detect and hold the time difference between the capstan control reference signal and the capstan rotation detection pulse signal during the playback operation, and detect and hold the time difference between the capstan control reference signal and the capstan rotation detection pulse signal. A delay time is maintained in proportion to the tracking error with a sensitivity equal to that of the capstan-controlled phase comparator, and a delay time based on the tracking error signal, a reference signal, and a cab.

This is achieved by delaying the reference signal based on the time difference between the stun rotation detection pulse signals and maintaining this delay time until after the start of recording.

[Effect]

A tracking error signal (hereinafter referred to as A
It is possible to obtain a capstan phase control signal that follows the TF signal.

Even after switching to the recording operation, the delay time of the reference signal is maintained, and the phase of the capstan is controlled using this delayed reference signal and the capstan rotation detection pulse signal. Capstan speed control operates in the same way during both playback and recording operations, and the capstan drive phase control signal does not change suddenly before and after switching to recording, minimizing disturbances in tape running speed. You will be held down.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be explained with reference to the drawings when applied to a DAT. FIG. 1 shows the configuration of a control circuit system, in which 1 is a magnetic tape, 2 is a rotary cylinder on which a magnetic head is mounted, 10 is a capstan shaft that drives the magnetic tape, 11 is a pinch roller, and 1 is a magnetic tape 1. is wound around the rotating cylinder 2 at 90 degrees. 3 is cylinder 2
4 is a frequency generator (hereinafter referred to as DF) that generates a frequency signal synchronized with the rotation of cylinder 2.
G), and the cylinder 2 is fixed to the rotating shaft of a cylinder motor 3. DP is a pulse signal that is output once per rotation at a predetermined rotational position of the cylinder 2.

The signal of the DFG 4 enters the frequency discriminator 5 and is converted into a voltage proportional to the frequency. 7 is a drive circuit for the cylinder motor 3, 8 is a phase comparison circuit between DP and a reference signal (ref) of 33Hz, which is frequency-divided from a crystal oscillator (not shown) inside the device, and 6 is the output of the frequency discriminator 5. This is an analog adder that adds the output of the phase comparator 8 and the output of the phase comparator 8. 12
13 is a drive motor for the capstan shaft 10, 13 is a frequency generator (hereinafter referred to as CFG) that generates a signal at a frequency of 400 Hz in synchronization with the rotation of the capstan shaft, and 14
is a frequency discriminator that generates a voltage proportional to the signal frequency of CF013, 16 is a drive circuit for the capstan motor 12, 15 is an analog adder, and 17 is the output of CFG 13 when the capstan motor 12 rotates at a determined speed. A frequency divider that divides the signal into a signal CP with the same frequency as the reference signal, 20, 24, and 29 are electronic switches that can be switched during recording and playback (the state in the figure shows the playback state), and 9 is mounted on cylinder 2. an ATF signal generation circuit that generates a tracking error signal from the reproduced signal of the rotating head;
19 is a DA converter, and 21.22 is a counter that is reset by a reference signal and counts a clock signal CLK having a frequency sufficiently higher than that of the reference signal. 23
26 is a DA converter that converts the count value of the counter 22 into a voltage; 27 is a latch circuit in which the count value of the counter 22 is stored by the CP multiplication signal; 27 is the output voltage of the DA converter 26;
A voltage comparator for comparing with the TF signal, 28 is voltage comparator 2
6 to 7.

30 is a latch circuit that stores the count value of the counter 22 at the timing of the output pulse of the mono multivibrator 28; 31 is a subtraction circuit that subtracts the output value of the latch circuit 30 from the output value of the latch circuit 23; 32 is a latch circuit that stores the subtraction result at the timing of the reference signal, 33 is a comparator that compares the output value of the latch circuit 32 and the counted value of the counter 22 to detect a match between the two, and 34 is a mono multivibrator. The output is a reset signal for the counter 21.

In the above configuration, the operation will be explained with reference to the signal diagram of each part shown in FIG.
The signal is converted into a voltage proportional to the rotational speed by the frequency discriminator 5, and becomes a speed control signal, which is connected to the reference signal of the phase comparator 8 and D
The rotation is controlled at a constant speed of 2000 revolutions per minute, which is the same as the reference signal, by the addition signal of the phase difference signal with P.

The rotation control of the cylinder 2 has the same configuration for both recording and reproduction. The capstan motor 13 outputs CFG during playback, 8.

The force signal is converted into a voltage proportional to the rotational speed by the frequency discriminator 14 to become a speed control signal, which is added to a voltage proportional to the tracking error by the ATF signal generation circuit 9 during regeneration operation and is negatively fed back to the motor drive circuit 16. The tape is controlled so that the rotating head traces the recording track. The count value of the counter 21 is stored in the latch 18 at the timing of the CP multiplied signal obtained by dividing the CFG signal, so the output of the DA converter 19 is proportional to the phase difference between the delayed reference signal and the CP multiplied signal, which will be described later. During the recording operation, this phase difference signal and the speed control signal are added to the adder 15.
The capstan motor 12 is driven at a constant speed in synchronization with the reference signal to run the tape at a constant speed, and data and tracking control signals are sent from the rotating head. recorded. next,
To explain the operation during splice recording, before starting splice recording, the playback operation starts from before the start part.

In Fig. 2, a is a reference signal, b is a CP multiplied signal,
The reference signal and CP during the reproduction operation have the same frequency due to the above-mentioned tracking control, but their phase relationship is uncertain. C
is the ATF signal. d indicates the count value of the counter 22, which is reset by the reference signal and increases linearly. e indicates the holding value when the count value d is latched in the latch 23 at the rising edge of CP, (the broken line indicates d)
This value n represents the time difference between a and C. The counted value of the counter 22 is determined by the DA converter 26, which is indicated by the broken line d' in f in FIG.
It is converted into a voltage that increases with time as shown in . Here, the conversion gain of the DA converter 26 is equal to that of the DA converter 19 used for phase comparison of the capstan motor. The output d' of the DA converter 26 is converted to A by the voltage comparator 27.
The TF signal type pressure is compared, and when d' becomes larger than the ATF voltage, the level of the voltage comparator 27 is inverted, and this is used as a trigger to operate the mono multivibrator 28 and output a pulse f. The count value of the counter 22 is stored in the latch 30 at the timing of the rise of f. g
indicates the value stored in the latch 30, and the value m corresponds to the phase difference when the output in the phase comparison of the capstan motor becomes equal to the ATF signal since the conversion gains of the DA converters 26 and 19 are equal. be. n in the subtracter 31
−m is subtracted, and the result is sent to the latch 32 as the reference signal r.
It is held at the rising edge of ef.

h indicates the value held by the latch 32. The comparator 33 compares the count value of the counter 22 and the value of nm, and triggers the mono-multivibrator 34 when the two match. Second
Figure i shows the output pulse d-r of the mono-multivibrator 34.
ef, and the time relationship between i and the reference signal a is such that the output in the phase comparison of the capstan motor is determined from the time when the count value of the counter 22 reaches nm, that is, from the phase difference between the reference signal and CP. It is assumed that the reference signal is delayed by a time period obtained by subtracting a phase difference that is equal to the ATF signal. j
indicates the count value of the counter 21, and the value held by the latch 18 is equal to m. Therefore, DA conversion output 1
The output of 9 is identical to the ATF signal as shown at ' in FIG.

Playback operation by switching switches 20, 24, and 29, 11
When the recording operation is switched from 0.degree. to the recording operation, the values of the latches 23 and 30 are held at the values immediately before switching, so even after switching, the reference signal continues to be delayed and output.

According to this embodiment, the phase control signal of the capstan can be made to follow the ATF signal with a delay of one cycle of the reference signal during the reproducing operation. FIG. 3 shows another embodiment,
The AD converter 35 converts the ATF signal into an AD signal.
The A converter 26, the voltage comparator 27, and the mono-multivibrator 28 are replaced, and the conversion gain of the AD converter 35 is the same as that of the DA converter 19. Therefore, the AD conversion output corresponds to the phase difference when the output in the phase comparison of the capstan motor becomes equal to the ATF signal, and is the same as g in Figure 2, and it is clear that it operates in the same way. It is.

It should be noted that the present invention is not limited to the above-described embodiment, and in the above-described embodiment, the reference signal is delayed, but the reference signal and the CP times signal are replaced, and 12.

The signal may be delayed by CP times.

〔Effect of the invention〕

According to the present invention, it is possible to perform the playback operation prior to continuous recording and obtain the capstan motor phase control signal that follows the ATF signal during the playback operation. The stun drive phase control signal does not change suddenly, and disturbances in the tape running speed are kept to a minimum, making it possible to continuously play back the spliced recorded portions without any problems, which in turn reduces the tape utilization rate. It can be improved and the effect is great.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of FIG. 1, and FIG. 3 is a circuit diagram showing another embodiment. 12...Capstan motor, 21.22...Counter, 18, 23, 30.32...Latch, 27...
・Voltage comparator, 19.26...DA converter, 31...
・Subtractor, 33... Comparator, 35... AD converter,
20°24.29...Switch. , 15.萬 2 膓α 膓〆'1 ． 1/I/+
e'Gohun, /l, /I. /l (L' /1 /l /I, Eng/
lueyu A6- /

Claims (1)

[Claims] 1. A cylinder on which a magnetic head is mounted and whose rotation is controlled at a constant speed in synchronization with the synchronization signal of the recording signal, and a capstan motor that drives the magnetic tape wound helically around the cylinder at a predetermined constant speed. During recording, the phase difference between the capstan rotation detection pulse signal synchronized with the rotation of the capstan motor and the reference signal generated inside the device is detected and the capstan motor is driven to move the magnetic tape at a constant speed. The data signal to be recorded and the signal for tracking control during playback are recorded on each inclined track. During playback, the tracking control signal detects the misalignment between the magnetic head and the recording track and returns it to the capstan motor. In a track-following helical scan magnetic tape device that performs track servo, the first means detects and holds a time difference between the capstan control reference signal and the capstan rotation detection pulse signal during a playback operation; , a second means for delaying the reference signal (or the capstan rotation detection pulse signal) with a sensitivity equal to that of the capstan-controlled phase comparator in proportion to the tracking error and maintaining the delay time; A continuous recording control circuit for a helical scan tape device, comprising means for delaying and holding a reference signal (or a capstan rotation detection pulse signal) based on the detection time difference of the means and the delay time of the second detection means.