JPH0729256A - Helical scanning type magnetic recording / reproducing apparatus - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a device of a helical scanning type magnetic recording / reproducing device that realizes highly accurate and highly responsive tracking control with a relatively simple circuit configuration. According to the present invention, tracking control is dynamically combined with a hill-climbing control method using an RF envelope signal and a timing signal control method that controls tracking so that timing signal detection in a reproduction signal has a predetermined timing. did. Specifically, by the decoding circuit 25 and the timing error processing circuit 27, the rotary head 4 at the time when the level of the envelope detection signal becomes maximum.
The time difference data from the track operation start time of A and B to the reproduction vertical sync signal detection time is set as tracking control target data, and a tracking error signal is obtained. This error signal is added to the speed error signal from the speed control circuit 20 and supplied to the capstan motor 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scanning type magnetic recording / reproducing apparatus, and more particularly to a helical scanning type magnetic recording / reproducing apparatus for performing tracking control using a reproduction envelope signal or a reproduction synchronization signal.

[0002]

2. Description of the Related Art In a helical scanning type magnetic recording / reproducing apparatus, it is necessary to perform tracking control so that a magnetic head correctly scans a track formed during recording during reproduction. There are various methods for this tracking control, for example, a CTL method using a CTL signal recorded on a linear track in the longitudinal direction of a magnetic tape, and an ATF using multiple pilot signals recorded on a helical track.
The method is widely used.

Among the above methods, the CTL method has a simple control process, but requires a dedicated linear track.
There is a need for a fixed head, which is a large component, as well as a decrease in the utilization efficiency of the magnetic tape. Further, the ATF method does not require a linear track and a fixed head, but on the other hand, the processing is complicated because it requires dedicated pilot signal detection which is mainly processed as an analog signal.

As a new method for these tracking control methods, for example, Japanese Patent Application Laid-Open No. 57-6 is proposed by the same applicant.
There has been proposed a tracking control method using a reproduction timing signal having timing information such as a synchronization signal or an index signal as disclosed in Japanese Patent No. 6559 or Japanese Patent Laid-Open No. 62-119764.

The tracking control system using the above timing signal does not require a linear track and a fixed head as in the CTL system, and does not perform complicated processing for detecting a pilot signal as in the ATF system.
Tracking control with high accuracy and excellent responsiveness can be realized.

[0006]

However, the above-mentioned conventional CTL system and ATF system have the above-mentioned problems, and the above-mentioned tracking control system using the timing signal has a problem in the vicinity of the center of tracking control. However, although excellent characteristics can be realized, it has the following problems. That is, the tracking is greatly deviated,
Timing cannot be detected when the reproduction timing signal cannot be detected due to a decrease in the reproduction signal level due to azimuth recording that is generally used in the current VTRs, or due to variations in the signal recording position on the tape that occur during compatible recording and reproduction with other devices. There is no particular consideration for tracking control such as when the signal reproduction timing varies, and there is a problem in reliability.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the above-mentioned problems of the prior art, and to perform tracking with high accuracy and excellent responsiveness in any tracking state with a relatively simple circuit configuration regardless of the VTR system. The present invention provides a helical scanning type magnetic recording / reproducing apparatus capable of realizing control.

[0008]

In order to achieve the above object, the present invention relates to a helical scanning type magnetic recording / reproducing apparatus, in which a drum rotation phase detecting means for generating a rotation phase detection signal of a drum having a rotary head mounted thereon. And a tape for selectively controlling the tape during reproduction so that the tape has a first traveling speed different from the tape traveling speed during recording and a second traveling speed equal to the tape traveling speed during recording. A tape traveling control means, a tape traveling drive means for traveling the tape in accordance with a control signal from the tape traveling control means, and an envelope detection signal of an RF signal output from the rotary head during reproduction. An envelope detecting means, a reproducing timing signal generating means for generating reproducing timing information such as a synchronizing signal in video information from the reproducing signal, the drum rotation phase detecting signal and the reproducing timing signal. When the time difference detection means for detecting a time difference or a phase difference and generating a timing time difference signal and the tape running control means control the tape running speed at the first running speed, the timing time difference signal And a timing time difference reference value generating means for generating a predetermined timing time difference reference value according to the information of the envelope detection signal, and a timing error signal is generated by comparing the timing time difference signal with the timing time difference reference value. When the timing error signal generating means and the tape running control means control the tape running speed at the second running speed, the timing error is generated.
The signal is added as a tracking error signal to the tape running control signal which is the output of the tape running control means, and the tape running control signal is output.
And a timing error signal returning means for returning to the driving means.

Further, according to the present invention, in a helical scanning type magnetic recording / reproducing apparatus, a drum rotation phase detecting means for generating a rotation phase detection signal of a drum having a rotary head and the tape at the time of reproduction are recorded. Tape traveling control means for controlling the traveling speed to be equal to the traveling speed of the tape, and tape traveling driving means for traveling the tape in accordance with a control signal from the tape traveling control means. Envelope detection means for generating an envelope detection signal of the RF signal output from the rotary head during reproduction, and increase / decrease of an envelope signal for detecting increase / decrease of the envelope signal using the envelope detection signal. Detection means, reproduction timing signal generation means for generating reproduction timing information such as a synchronization signal in video information from the reproduction signal, the drum rotation phase detection signal and the reproduction A predetermined timing time difference reference value using a timing time difference detecting means for detecting a time difference or a phase difference from the imming signal and generating a timing time difference signal, the detection signal of the increase / decrease detecting means for the envelope signal and the timing time difference signal. Timing timing difference reference value generating means, timing timing difference signal generating means for generating a timing error signal by comparing the timing time difference signal with the timing time difference reference value, and the timing error signal tracking error signal. A signal is added to the tape traveling control signal which is the output of the tape traveling control means as a signal, and is returned to the tape traveling drive means.

Further, according to the present invention, in the helical scanning type magnetic recording / reproducing apparatus, the drum rotational phase detecting means for generating the rotational phase detecting signal of the drum and the tape during reproduction, the tape traveling during recording, Tape traveling control means for controlling the traveling speed to be equal to the speed, tape traveling driving means for traveling the tape according to the control signal of the tape traveling control means, and output of the rotary head during reproduction. And an envelope detecting means for generating an envelope detection signal of the RF signal, and an envelope using the envelope detection signal.
Increase / decrease of an envelope signal for detecting increase / decrease of a read signal, reproduction timing signal generating means for generating reproduction timing information from a reproduction signal, time difference or phase difference between the drum rotation phase detection signal and the reproduction timing signal. Timing timing difference detection means for generating a timing time difference signal, a timing time difference reference value generating means for generating a predetermined timing time difference reference value, and a timing time difference reference value varying means for increasing or decreasing the timing time difference reference value by a predetermined amount. And a timing error signal generating means for generating a timing error signal by comparing the timing time difference signal with the timing time difference reference value, and the timing error signal is an output of the tape running control means. Add to tape running control signal and return to tape running drive means And a signal feedback means, the envelope - - that timing error in accordance with the detection signal of the increase and decrease detecting means flop signal, and a configuration for controlling the increase and decrease of the timing time difference reference value.

[0011]

First, the drum rotation phase detecting means generates scanning position information of the rotary head in the track longitudinal direction.
Tape traveling control means for selectively controlling the first traveling speed and the second traveling speed to control the first traveling speed to a tape traveling speed different from that during recording. Thus, the just tracking state is searched by changing the tracking state with time, and the second traveling speed control realizes normal reproduction in which the tape traveling speed is controlled to the same tape traveling speed as during recording. The first traveling speed control is set only for the time required to generate the timing time difference reference value described later, and the second traveling speed control is performed after the timing time difference reference value is set. The tape traveling drive means amplifies the power of the tape traveling control signal or the tracking traveling signal supplied from the tape traveling control means, and at the same time, the tape traveling driving signal is supplied to the motor. The drive power corresponding to the rotation phase is supplied to the motor. Envelop
The detection means detects the envelope of the output signal of the rotary head and monitors the tracking state. The reproduction timing signal generating means detects a timing signal included in the reproduction information (in other words, a detection signal of predetermined position information in the longitudinal direction of the recording track). The timing time difference detection means detects, for example, the time from the track scanning start point of the rotary head to the detection point of the reproduction timing signal. This is nothing but the detection of the relative tracking state. The timing time difference reference value generating means searches the tracking state by monitoring the output of the envelope detecting means at the first tape traveling speed, and the just tracking state, that is, the level of the envelope detecting signal is maximum. The timing time difference in such a state is set as the timing time difference reference value. This is the control center (control target) in tracking control.

The timing error signal generating means compares the detected timing time difference signal output from the timing time difference detecting means with the timing time difference reference value signal output from the timing time difference reference value generating means. Signal, i.e. tracking error
Generate a signal. The timing error signal feedback means adds the timing error signal to the tape traveling speed control signal and supplies it to the tape traveling drive means.

Even if the recording position of the timing signal is different due to the self-recording / reproduction due to the above configuration and operation, the timing time difference reference value in the just tracking state that maximizes the envelope detection signal is set, so that it is high. Tracking control with high accuracy and excellent responsiveness can be realized.

Further, since the envelope signal increase / decrease detecting means and the timing time difference reference value varying means control the increase / decrease of the timing time difference signal reference value in accordance with the detection signal of the envelope signal increase / decrease detecting means, the envelope signal is always changed. It is possible to set the tracking control center so that the loop signal becomes maximum, and it is possible to perform even more highly accurate tracking control.

With the above-mentioned configuration means and operation, tracking control with high precision and excellent responsiveness is realized with a relatively simple circuit configuration regardless of the VTR system, which is the object of the present invention, in any tracking state. It is possible to realize a helical scanning type magnetic recording / reproducing apparatus.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. First, the principle of tracking control using a reproduction timing signal in a helical scanning magnetic recording / reproducing apparatus will be described with reference to FIG.

FIG. 2 schematically shows an example of a recording track in a helical scanning type magnetic recording / reproducing apparatus and a scanning locus of a rotary head during reproduction. In the case of guard bandless, azimuth recording is generally used, but the azimuth angle and the like are not shown in order to simplify the figure. In FIG. 2, T1 to T3 are recording tracks, S1 to S3 are timing signal recording positions of each track, and 4 is a rotary head. In the case of helical scanning, since there is a finite track width, the recording start position of each track has a stepped shape as shown by αH in FIG. If the rotary head 4 at the time of reproduction scans the track T2 and the tracking is deviated and follows the scanning locus shown by the dotted line, the track scanning start point deviates from the S0 point to the SE point. Therefore, the detection time of the timing signal S2 reproduced from the T2 track is Δ compared to the case of just tracking.
It will be shifted by τ. The deviation of the reproduction time of this timing signal is proportional to the tracking deviation amount Δe. Tracking control can be performed by returning the deviation of the reproduction time of the timing signal as a tracking error signal to the tape traveling system.

A problem with the tracking control by detecting the deviation of the reproduction time of the timing signal is that the reproduction signal level decreases (S /
(N is deteriorated), the reproduction timing signal cannot be detected, and in the compatible recording / reproduction with other devices, the range of variation of the timing signal position recorded on the tape is sufficiently larger than αH in FIG. Since it cannot be made small, the detection time (center of tracking control) of the timing signal at the time of just tracking cannot be uniquely determined. The present invention solves these problems by the configuration described below.

Next, one embodiment of the present invention will be described in detail with reference to FIG. In this embodiment, a video tape recorder (VTR) is used as a helical scanning type magnetic recording / reproducing apparatus.
Will be described as an example. FIG. 1 is a block diagram mainly showing a reproduction tracking control system in a VTR to which the present invention is applied. In FIG. 1, 1 is a magnetic tape, 2 is a drum, 3 is a drum motor, 4A and 4B are magnetic heads, 5 is a capstan, 6 is a capstan motor, 7 is a DFG sensor, and 8 is a DPG sensor. , 9 are CFG sensors-1
0 to 12 are sensor amplifiers, and 13 and 14 are MDA (mode
(Driver driver amplifier), 15 is a switch circuit, 16 is a recording amplifier, 17 is a preamplifier, 18 is a video / audio processing circuit at the time of recording / reproducing, 19 is a drum rotation control circuit, 20 is a capstan speed control circuit, and 21 is a cap. Stan phase control circuit, 22 is an addition circuit, 23 is a switch circuit, 24 is an envelope detection circuit, 25 is an envelope detection signal decoding circuit, 26 is a synchronization signal detection circuit, and 27 is a timing error processing circuit. 28 to 31 are input / output terminals for video signals and audio signals. The operation will be described in detail below.

First, referring to FIG. 1, the rotary heads 4A and 4B are shown.
The rotation control during reproduction of the drum 2 (same as drum motor 3) equipped with will be described. In FIG. 1, D
The FG sensor-7 and the DPG sensor-8 are drum models.
From the DFG magnet and the DPG magnet (not shown) magnetized in the controller 3, respectively.
Detect the signal. The DFG signal and the DPG signal are respectively amplified by the sensor-amplifiers 10 and 11 and converted into logic level signals, and then supplied to the drum rotation control circuit 19 and the timing error processing circuit 27.

The drum rotation control circuit 19 digitally measures the period of the DFG signal as a speed control process and performs comparison calculation with the target period to generate a speed error signal.
As a phase control process, a phase difference between a DPG signal and a reference signal (not shown) supplied from a drum rotation phase reference signal generation circuit is measured to generate a phase error signal. After adding the velocity error signal and the phase error signal, the MDA13
Is supplied to the drum motor 3 via the. As a result, the drum motor 3 is rotated at a predetermined speed and phase. The drum rotation control circuit 19 switches the internal switch circuit (not shown) of the preamplifier 17 so that the output signals of the rotary heads 4A and 4B are continuous in connection with the phase control processing. Is supplied to the preamplifier 17.

Next, the control at the time of reproduction of the capstan 5 (which is synonymous with the capstan motor 6) for performing tape running control will be described. In FIG. 1, a CFG sensor-9 detects a frequency signal (CFG signal) proportional to the rotation speed of the capstan motor 6. The CFG signal is amplified by the sensor-amplifier 12, converted into a logic level signal, and then supplied to the capstan speed control circuit 20 and the capstan phase control circuit 21. The capstan speed control circuit 20 digitally measures the cycle of the CFG signal, performs comparison calculation with the target cycle to generate a speed error signal, and supplies it to the adder circuit 22.

On the other hand, the capstan phase control circuit 21
A phase difference between the CFG signal and a reference signal supplied from a capstan rotation phase reference signal generation circuit (not shown) is measured to generate a phase error signal, which is supplied to one input terminal of the switch circuit 23. The capstan phase error signal can also be generated by integrating the speed error signal output from the capstan speed control circuit 20. The speed error signal and the phase error signal supplied via the switch circuit 23 are added by the adder circuit 22 and then supplied to the capstan motor 6 via the MDA 14. As a result, the capstan motor 6 is rotated at a predetermined speed and phase.

The tracking control operation of the main part of the present invention will be described in detail below. Blocks that play an important role in tracking control are surrounded by the dotted line in the figure.
~ 27. In this embodiment, the tracking control mode has two modes, and the first mode is the transient mode.
This mode is called a mode, and is a mode in which the tape traveling speed is controlled so as to be consciously different from the tape traveling speed at the time of recording. The second mode is a mode called a steady mode, in which the tape traveling speed is controlled to be the same as the tape traveling speed at the time of recording.

First, the transient mode which is the first mode will be described. The transient mode is a timing signal detection time at the time of just tracking (mainly tracking control), which is a problem in tracking control using the timing signal reproduction time described in the latter half of "Means for Solving Problems". This is a mode for solving the problem that cannot be uniquely determined.

In FIG. 1, the capstan speed control circuit 20 and the capstan phase control circuit 21 are not shown when the tracking control state is not in a steady state such as at the start of reproduction, in other words, when the tracking control is unlocked. However, the control target speed is controlled by the control signal from the system controller so as to be different from the tape traveling speed at the time of recording. At this time, the switch circuit 23 is closed on the side of the phase control circuit 21, so that the capstan motor 6 travels the tape at a speed different from the tape travel speed at the time of recording. in this case,
Since the tape traveling speed is different from that at the time of recording, the rotary head slightly scans the recording track obliquely. Therefore, the tracking state gradually changes with time, and the level of the envelope detection signal, which is the output of the envelope detection circuit 24 to which the output of the preamplifier 17 is supplied, also changes with time.

On the other hand, the sync signal detection circuit 26 to which the reproduction signal is supplied detects the vertical sync signal of the video signal, for example, from the reproduction signal and supplies the vertical sync signal VS to the timing error processing circuit 27. The timing error processing circuit 27 first detects the rotational phase information of the drum, that is, the track scanning position of the rotary head based on the DFG signal or the DPG signal, and compares it with the reproduction timing of the supplied vertical synchronizing signal VS. For example, the time difference between the track scanning start time of the rotary head shown in FIG. 2 and the reproduction vertical synchronization signal VS (corresponding to S1 to S3) is measured.

In the transient mode, since the tape traveling speed is different from that during recording as described above, the reproducing vertical synchronizing signal VS is measured from the start of track scanning of the rotary head measured by the timing error processing circuit 27. The time difference until the detection time point of will change with time. FIG. 3 shows an example of the time difference between the start of track scanning of the rotary head and the time of detection of the reproduction vertical synchronizing signal VS and the temporal change of the envelope detection signal level.

In FIG. 3, the horizontal axis t is the elapsed time, the figure (1) shows the envelope detection signal level, and the figure (2).
Indicates the detection time difference of the reproduction vertical synchronization signal VS. In the figure (1), the tracking error Δe = 0 when the envelope detection signal level is peaked. In the figure (2), the detection time difference of the reproduction vertical sync signal VS is τ0 during the just tracking. On the other hand, a time difference corresponding to ± αH occurs. In addition, the dotted line a1 in FIG.
, A2 (a period above and below a2) represents a region (period) in which the tracking vertical deviation is large and correct detection of the reproduced vertical synchronizing signal is difficult. Further, FIG. 3 does not reflect the delay time required for the envelope detection and the timing signal detection for simplification.

The envelope detection signal decoding circuit 25 shown in FIG. 1 monitors the level of the envelope detection signal supplied from the envelope detection circuit 24 as shown in FIG. , The control signal 38a is supplied to the timing error processing circuit 27 when the level of the envelope detection signal becomes maximum. The timing error processing circuit 27
According to the control signal 38a from the decoding circuit 25, the time difference data from the track scanning start time of the rotary head at the time when the level of the envelope detection signal becomes maximum to the detection point of the reproduction vertical synchronizing signal VS. Is set as the tracking control target data.

After setting the tracking control target data, the decoding circuit 25 operates in the capstan speed control circuit 2.
0 and the control signal 37a are supplied to the phase control circuit 21, and the control signal 38a is supplied to the switch circuit 23 so as to close the switch circuit 23 to the timing error processing circuit side. The above is the operation of the main block in the transient mode which is the first mode.

The deviation of the tape running speed from the recording speed in the transient mode, that is, the speed offset is set on the basis of the following conditions. First, the larger the velocity offset, the shorter the time required for tracking phase shift, and the faster the setting of the tracking control center that maximizes the level of the envelope signal can be made.
However, the tracking phase shift amount per unit time becomes large and a large error is included in the setting of the tracking control center due to the delay time in detecting the envelope signal. Since the time required to detect the envelope (delay time) can be estimated at the time of circuit design, it is possible to make a correction to offset this delay time. Further, if the velocity offset is increased, the response time of the velocity control becomes long in the process of switching from the transient mode to the steady mode, which is not preferable. Therefore, it is necessary to determine the speed offset in the transient mode by comprehensively evaluating the shortening of the setting time of the tracking control center, the improvement of accuracy of the tracking control center, the pull-in time of the speed control system, and the like.

FIG. 4 shows the velocity offset amount, the time required for the tracking phase shift for one track, and the one frame time (unit time for detecting increase / decrease of the envelope detection signal).
3 shows the relationship of the level change amount of the envelope detection signal in FIG. In this embodiment, the velocity offset amount is -5% when the transient mode is finished in several hundred milliseconds to less than 1 second.
Is set to. The speed offset amount is set to a negative value because the acceleration control is faster in response than the deceleration control in a general household VTR, so that the speed is quickly set when switching from the transient mode to the steady mode. This is so that the mode can be changed.

Next, the steady mode, which is the second mode, will be described. In the steady mode, the capstan speed control circuit 20 controls the control target speed to be the same as the tape traveling speed during recording. In the phase control circuit 21, the switch circuit 23 has a timing error processing circuit 2
The operation is not reflected because it is closed on the 7 side.

Instead, the timing error processing circuit 27
Generates a timing error signal, that is, a tracking error signal, from the time difference data (control center data) set in the transient mode and the detection timing of the vertical synchronizing signal VS actually reproduced. The adder circuit 22 receives a speed error signal from the capstan speed control circuit 20 whose control target is the same as the tape traveling speed at the time of recording, and a timing error processing circuit supplied via the switch circuit 23. After adding the tracking error signal from 27,
It is supplied to the capstan motor 6 via the MDA 14. As a result, the capstan motor 3 is rotated at the recording speed with a predetermined tracking phase.

Blocks not described above in FIG. 1 operate similarly to the conventional VTR, and will not be particularly mentioned here.

The functions of the envelope detection signal decoding circuit 25 and the timing error processing circuit 27, the operation of which has been described above, and the specific circuit construction for realizing the functions will now be described in detail. FIG. 5 shows a specific configuration example.
In FIG. 5, the block surrounded by the dotted line 25 is the decoding circuit 25, and the block surrounded by the dotted line 27 is the timing error processing circuit 27.

In FIG. 5, reference numeral 32 is an input terminal for the envelope detection signal ENV, and 33 and 34 are DFG signals and D.
PG signal input terminal, 35 is a time measuring clock C generated by a stable oscillator (not shown) using a crystal or the like
K1 is an input terminal, 36 is an input terminal for a vertical synchronizing signal VS in a video signal, 37 and 38 are output terminals for a control signal, 3
9 is a timing error signal (tracking error signal)
Output terminal. In addition, the constituent elements of each block are 4
0 and 49 are averaging circuits, 41, 42, 48 and 50 are latch circuits, 43 is a comparison circuit, 44 is a control signal generation circuit, 4
6, 52 are decoding circuits, 45 and 47 are counter circuits,
51 is a subtraction circuit, 53 is a maximum limit data generation circuit,
Reference numeral 54 is a minimum limit data generation circuit, 55 is a zero data generation circuit, and 56 is a switch circuit.

First, the operation of the envelope detection signal decoding circuit 25 will be described in detail. In FIG.
The envelope detection signal ENV supplied via the input terminal 32 is latched in the latch circuit 41 after the instantaneous fluctuation is suppressed by the averaging circuit 40. The signal latched by the latch circuit 41 is supplied to the latch circuit 42 and the comparison circuit 43 at the next stage. The latch circuits 41 and 42 perform a latch operation at a predetermined sampling cycle. Comparison circuit 4
The other input terminal of 3 is supplied with the signal latched by the latch circuit 42, and the level change amount of the envelope detection signal over time of the sampling cycle is calculated. The level change signal of the envelope detection signal is supplied to the control signal generation circuit 44. The control signal generating circuit 44 decodes the level change signal of the envelope detection signal, and when the level of the envelope detection signal reaches the maximum level, the first and second control signals 37a, 3 are generated.
8a is generated.

The first control signal 37a is supplied to the capstan speed control circuit 20 and the phase control circuit 21 of FIG. 1 through the output terminal 37. The control signal 37a sets the control target values of the capstan speed control circuit 20 and the phase control circuit 21 to the same tape traveling speed as that at the time of recording. The capstan speed control circuit 20 and the phase control circuit 21 set a control target value having a speed offset of -5% with respect to the time of recording until the first control signal 37a is supplied.

The second control signal 38a is supplied as a latch clock to the switch circuit 23 and the latch circuit 50 of FIG. 1 through the output terminal 38. The switch circuit 23 is closed to the output signal side of the timing error processing circuit 27 in response to the second control signal 38a. The latch circuit 50
Generates the timing time difference reference value described above.

Next, the timing error processing circuit 27 including the latch circuit 50 will be described. In FIG. 5, the DFG signal and the DPG signal input via the input terminals 33 and 34 are supplied to the counter circuit 45 as a clock and a reset signal. The count value of the counter circuit 45 is supplied to the decoding circuit 46. Decoding circuit 46
Detects a predetermined count value, and the counter circuit 47 at the next stage
Supply a reset signal to. The clock CK1 for time measurement is supplied to the counter circuit 47 via the input terminal 35. The count value of the counter circuit 47 is supplied to the latch circuit 48 as data. Latch circuit 48
Latches the count value of the counter 47 with the vertical synchronizing signal VS supplied through the input terminal 36 as a clock.

By the operations of the blocks 45 to 48 described above, the latch signal of the latch circuit 48 is time difference information (timing time difference signal) from the time when the phase detection signal of the rotary head is generated to the time when the vertical synchronizing signal, which is a timing signal, is detected. Will have.

The timing time difference signal which is the output signal of the latch circuit 48 is supplied to the subtraction circuit 51 and
The averaging circuit 49 suppresses the momentary fluctuation, and then supplies it to the latch circuit 50. As described above, the latch circuit 50 is supplied with the control signal of the control signal generation circuit 44 as the latch clock, and therefore latches the timing time difference signal at the time when the level of the envelope detection signal becomes maximum. This latched timing time difference signal becomes a control target in tracking control, that is, a timing time difference reference value signal.

The timing time difference reference value signal output from the latch circuit 50 is supplied to the subtraction circuit 51. The subtraction circuit 51 subtracts the timing time difference signal which is the output of the latch circuit 48 and the timing time difference reference value signal which is the output of the latch circuit 50, which changes from moment to moment according to the tracking state, to obtain a timing error signal which is a tracking error signal. A signal is applied to the first input terminals of the decoding circuit 52 and the switching circuit 56. Other 3 of switch circuit 56
Each of the two input terminals has a maximum limit value generation circuit 5
The maximum limit signal supplied from No. 3 and the minimum limit signal supplied from the minimum limit value generation circuit 54 and the zero value signal supplied from the zero data generation circuit 55 are input, and switching of these input signals is performed. Decoding circuit 5
It is performed by the control signal supplied from 2. The decoding circuit 52 outputs the timing error output from the subtraction circuit 51.
The signal is decoded and a switching control signal for the switch circuit 56 is generated.

The switching control signal generation algorithm of the switch circuit 56 is as follows. First, in the range that the timing error signal can take, ± αH is the theoretical maximum deviation of the timing error signal with respect to the tracking deviation of ± 1 track as shown in FIG. 2 or FIG. Further, when the timing error signal is in the vicinity of ± αH, the S / N of the reproduced signal is significantly deteriorated, so that the reliability of the detection timing of the reproduced vertical synchronizing signal is low.

From the above, in this embodiment, the timing error
Timing error is within the range of signal error ± αH / 2
The signal is output as it is, and the timing error signal error
In the range where the minute is αH / 2 or more and αH or less, αH / 2 is output as the maximum limit signal, and in the range where the error of the timing error signal is −αH / 2 or less and −αH or more, the minimum limit signal is −αH. If the absolute value of the error of the timing error signal exceeds .alpha.H, the detected timing error signal is judged to be invalid and a zero value signal is output. The timing error signal output by the above switching control is supplied to the adder circuit 22 via the output terminal 39 and the switch circuit 23 of FIG. 1, added with the speed control signal of the capstan, and fed back to the capstan motor 6. It

As described above, according to the present embodiment, the tracking control mode has two modes, and in the first mode (transient mode) for a short time, the just tracking state is set. It is possible to set the following tracking control center (control target), and it is possible to perform highly accurate tracking control in the second mode (steady mode). Therefore, even if there is a deviation such as a track recording position in the self-recording reproduction, which has been a problem in the past, it is possible to perform highly accurate tracking control without any problem. Moreover, since no special signals such as the conventional CTL signal and pilot signal are required, the signal processing system for them is unnecessary, and the tracking is performed only by the timing signals such as the reproduction RF signal and the synchronization signal originally existing in the VTR. Since it can be controlled, it can be commonly used for each VTR regardless of the VTR system.

In this embodiment, in the switching control of the switch 56 of FIG. 5, when the absolute value of the error component of the timing error signal exceeds αH, the detected timing error signal is judged to be invalid and the zero value is obtained. Although the signal is output, in this case, there is no problem even if the previous value of the effective timing error signal is held (not shown) instead of outputting the zero value signal.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings. Also in this embodiment, a video tape recorder (VTR) will be described as an example of a helical scanning type magnetic recording / reproducing apparatus. In the present embodiment, the basic structure is the same as the block structure shown in FIG. 1, so the basic structure will not be mentioned again. This embodiment is different from the first embodiment in the configuration and operation of the envelope detection signal decoding circuit 25 and the timing error processing circuit 27 in FIG. FIG. 6 shows an example of a concrete configuration block of the envelope detection signal decoding circuit 25 and the timing error processing circuit 27 in this embodiment. Prior to a detailed description of the specific configuration block example of FIG. 6, the essential points of this embodiment, that is, the differences from the first embodiment described above, will be briefly described.

In the first embodiment, the tracking modes are the first mode (transient mode) and the second mode (steady mode).
In the second embodiment, the tracking mode is divided into a plurality of modes including the first mode (transient mode). The greatest difference, that is, the characteristic, is that the tracking mode is classified into the following modes and the tracking mode is changed to the optimum tracking mode according to the tracking state that changes from moment to moment. The operation will be briefly described. After setting the tracking control target in the transient mode, the operation shifts to the steady mode. However, even in the steady mode, the tracking control target set in the transient mode is set. But,
Whether or not the tracking control target realizes just tracking is constantly monitored, and if it is out of the just tracking state, by resetting the tracking control target, for example, during joint recording between different sets during recording. Even if there is a slight discontinuity in the track or the recording position of the timing signal is deviated as in the case of performing it, by resetting the tracking control center quickly and accurately, further high precision tracking control can be achieved. It makes it possible.

The operation will be described in detail below with reference to FIG. In FIG. 6, 57 is an averaging circuit, 58 is a latch circuit, 59 is a 3-input comparison circuit, 60 is a control signal generating circuit, 61 is an adding circuit, and 62 is a minute tracking phase shift signal.
The other blocks are the same as the blocks with the same reference numerals shown in FIG.

In the configuration of FIG. 6, the operations other than the newly provided blocks 57 to 62 are the same as the operations described in the previous embodiment, and the description thereof is omitted here. The operation of the new block will be described below.

The purpose of providing the new block is to constantly monitor whether or not the tracking control target set in the previous transient mode is a tracking control target for achieving just tracking in the steady mode. In the case where there is a deviation from the just tracking state, the tracking control target is reset to enable even higher precision tracking control.

In FIG. 6, the averaging circuit 57 suppresses the instantaneous fluctuation of the envelope detection signal output from the latch circuit 41 with a time constant larger than that of the averaging circuit 40. The output of the averaging circuit 57 is supplied to the latch circuit 58 and the B input terminal of the comparing circuit 59. The latch circuit 58 latches the output signal of the averaging circuit 57 at a sampling period longer than the sampling period of the latch circuits 41 and 42,
The latch signal is supplied to the A input terminal of the comparison circuit 59. In addition to the above-mentioned two signals, the output signal of the latch circuit 41 is supplied to the C input terminal of the comparator circuit 59.

The comparison circuit 59 compares the A terminal signal and the B terminal signal and the A terminal signal and the C terminal signal, and supplies a comparison result signal to the control signal generation circuit 60. The comparison signal between the A terminal signal and the B terminal signal detects an increase / decrease in the envelope detection signal in a relatively long time interval, and the comparison signal between the A terminal signal and the C terminal signal is smoothed (averaged). It becomes a comparison signal between the envelope detection signal level and the almost instantaneous instantaneous envelope detection signal level.

The control signal generating circuit 60 decodes the two comparison result signals to generate a fine tracking phase shift signal.
The data generation circuit 62 (hereinafter simply referred to as the phase shift data generation circuit 62) is controlled. The phase shift data generation circuit 62 generates a signal that offsets the value of the timing time difference reference signal by a predetermined minute amount in the steady tracking state. First, the phase shift data generation circuit 62 generates a minute phase shift signal so that the value of the timing time difference reference signal is offset by a predetermined minute amount. This slight phase shift signal is supplied to the adder circuit 61. The adder circuit 61 adds the minute phase shift signal to the timing time difference reference signal output from the latch circuit 50. Therefore, the subtraction circuit 5
The timing error signal (tracking error signal) generated at 1 has an offset, and the tracking phase is shifted according to this offset. As a result, the level of the envelope detection signal of the reproduction signal changes. The change in the level of the envelope detection signal is detected by the comparison circuit 59 by comparing the A terminal signal and the B terminal signal.

If the comparison result shows that the level of the envelope detection signal is increased, it means that the tracking phase is shifted to the just tracking state.
0 supplies a control signal to the phase shift data generating circuit 62 so as to generate a minute phase shift signal with the same polarity. on the other hand,
When the level of the envelope detection signal decreases due to the addition of the minute phase shift signals, the tracking phase shifts in the direction further away from the just tracking state, so the control signal generation circuit 60 causes the phase shift A control signal is supplied to the clock generation circuit 62 so as to generate a minute phase shift signal with reverse polarity. By repeating the above operation, tracking control that always maintains the just tracking state can be realized.

However, if the generation of the minute phase shift signal and the variable period in the phase shift data generation circuit 62 are shortened, the frequency component in which the tracking meanders near the just tracking state becomes a disturbance of the drum rotation system and causes a jitter of the video signal. It leads to deterioration of characteristics. Therefore, it is necessary that the generation and variable cycle of the minute phase shift signal be equal to or longer than the cycle capable of ensuring sufficient disturbance suppression characteristics in the drum rotation control system.

Further, when the continuity of the tracks is interrupted during joint recording during recording, the tracking phase is shifted to the just tracking state by adding the minute phase shift signal to the already set timing time difference reference signal. It will take a long time to do. In order to solve this, in the present embodiment, the comparison circuit 59 compares the A terminal signal and the C terminal signal to obtain a smoothed (averaged) envelope detection signal level and an almost instantaneous envelope detection signal level. Are compared, and when the level of the C terminal signal is significantly reduced for a certain period of time or longer, the steady tracking state is exited, and the first mode ( The transition to the transient mode) and the generation of the minute phase shift signal in the phase shift data generation circuit 62 are stopped.

As described above, according to this embodiment, as in the previous embodiment, even if there is a deviation in the track recording position or the like in the other-personal recording / reproduction which has been a problem in the related art, there is no problem and the accuracy is high. Tracking control can be performed. Moreover, since no special signals such as the conventional CTL signal and pilot signal are required, the signal processing system for them is unnecessary, and the tracking is performed only by the timing signals such as the reproduction RF signal and the synchronization signal originally existing in the VTR. Since it can be controlled, it can be commonly used for each VTR regardless of the VTR system. Further, in the present embodiment, the increase / decrease of the envelope signal is detected even in the steady tracking control state, and the timing time difference reference value is variably controlled so that the envelope signal is always maximized. The tracking control center can be set quickly and accurately even in the case of a minute discontinuity of the track due to continuous shooting or the recording position of the timing signal is different, which enables even higher precision tracking control. .

In the above embodiments, the decoding circuit 25 for the envelope detection signal has been described as one system (one channel) as shown in FIGS. 5 and 6.
In a home VTR or the like, it is general that a plurality of rotary heads are used. In this case, the level of the envelope detection signal of the reproduction signal varies considerably (about several dB) depending on the rotary heads. Therefore, increase / decrease comparison of the envelope detection signal using the output signal between different rotary heads causes a malfunction. On the other hand, if the tracking control is performed by detecting the increase / decrease of the envelope detection signal using the output signal of one specific rotary head, only the above specific rotary head has priority tracking control, and head step differences among a plurality of rotary heads, etc. As a result, the tracking accuracy of other rotary heads is significantly deteriorated. To solve this problem, the decode circuit 25 for the envelope detection signal is used.
The signal system of is made multi-channel, the increase / decrease of the envelope detection signal is detected for each rotary head, and the tracking control may be performed so that the total envelope detection signal level becomes the maximum. 5
The configuration shown in FIG. 6 can be used as it is.

When there are a plurality of rotary heads, the mounting accuracy of the rotary heads (18 in the case of two heads facing each other by 180 degrees is 18).
The reproduction timing of the timing signal such as the vertical synchronizing signal varies depending on the accuracy of 0 degree and the accuracy of the head step. In this case, there is no problem if the timing time difference reference value is set for each rotary head. However, when the timing error signal is generated with one timing time difference reference value, the value of the timing error signal is different for each rotary head. A disturbance having a frequency component that is one half of the track scanning frequency is generated. In this case, for example, as shown in FIG. 7, at the output stage of the timing error signal, one half of the track scanning frequency is set.
Frequency component (for example, 180 degree opposite two-head type NTSC-
In the case of VTR, it becomes 30 Hz. The influence of the disturbance can be suppressed by inserting the notch filter 65 that selectively suppresses (1).

In the above-mentioned embodiments, the hardware has been mainly described as the specific configuration. However, the recent improvement in the processing capability of the microcomputer makes it possible to implement the signal processing as described above by software. FIG. 8 shows a schematic configuration for realizing the present invention when a one-chip microcomputer used for servo control or the like is used.

In FIG. 8, input terminals 33 to 36 are the same as the input terminals having the same reference numerals in FIG. 5 or FIG. 6, and 75 is a CFG input terminal. Reference numeral 61 is an AD converter for taking in the envelope detection signal ENV, 6
7 is a general-purpose counter, 68 is a CPU, 69 is a RAM, 70
Is a program ROM, and 71 and 72 are DAs for outputting rotation control signals to the drum motor and the capstan motor.
It is a converter.

Using the above-mentioned one-chip microcomputer, a program flow (P
Corresponding to the AD diagram) are shown in FIGS. 9 to 12. FIG. 9 shows the processing from the start of the capstan activation to the setting of the timing time difference reference value data which is the tracking control center (control target). FIG. 10 shows a further tracking accuracy improving process in the steady tracking state. FIG. 11 shows the monitoring processing of the timing error signal generated from the reproduction synchronization signal. FIG. 12 shows the level monitoring processing of the reproduction envelope signal.

By using the software processing as described above, it is possible to realize tracking control with high accuracy and excellent responsiveness as in the case of the hardware configuration described above.

In the above embodiments, the signal whose reproduction timing changes according to the tracking state is
Although the case where the vertical synchronizing signal (V synchronizing signal) in the video signal is used has been described, the timing signal for tracking is not limited to the V synchronizing signal and may be a plurality of predetermined horizontal synchronizing signals. It may be an index signal newly superimposed on the recorded information.

Furthermore, a digital VTR or DAT
Even in a device that records information as a digital signal as described above, it is apparent that the tracking control can be realized in the same manner as described above by using the synchronization signal of the information block or the address signal as the tracking timing signal.

[0070]

As described above, according to the present invention,
It is possible to realize a helical scanning type magnetic recording / reproducing apparatus which realizes tracking control with high accuracy and excellent responsiveness regardless of the tracking state, regardless of the tracking state, regardless of the VTR method.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a helical scanning type magnetic recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of a tracking control method using a timing signal.

FIG. 3 is a diagram showing a relationship between timing error information and an envelope signal level.

FIG. 4 is a relationship diagram showing a capstan velocity offset amount, a tracking phase shift time, and an envelope level change amount.

FIG. 5 is a block diagram showing a configuration of a main part of the first embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a main part of a second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration example for suppressing a specific frequency disturbance of a tracking error signal.

FIG. 8 is a block diagram showing a configuration example of a microcomputer when the tracking control according to the present invention is performed by software.

FIG. 9 is a process flow chart of a startup routine when the tracking control of the present invention is performed by software.

FIG. 10 is a processing flowchart of a tracking precision improving routine when the tracking control of the present invention is performed by software.

FIG. 11 is a processing flow chart of a synchronization signal detection time monitoring routine when the tracking control of the present invention is performed by software.
It is a figure.

FIG. 12 is a processing flowchart of an envelope decrease detection routine when the tracking control of the present invention is performed by software.

[Explanation of symbols]

1 is a magnetic tape, 2 ... drum, 3 ... drum motor, 4A, 4B ... rotary magnetic head, 5 ... capstan, 6 ... capstan motor, 7 ... DFG sensor, 8 ...... DPG sensor-, 9 ... is CFG sensor-,
10 to 12 sensor-amplifier, 13, 14 ... MDA (motor driver-amplifier), 10, 12 ... filter circuit (characteristic compensation circuit), 15 ... switch circuit, 16, 1
7 ... Recording and playback preamplifier, 18 ... Video / audio processing circuit during recording / playback, 19 ... Drum rotation control circuit, 2
0 ... Capstan speed control circuit, 21 ... Capstan phase control circuit, 22, 61 ... Addition circuit, 23 ... Switch circuit, 24 ... Envelope detection circuit, 25 ...
Decode circuit for envelope detection signal, 26 ... Vertical sync signal separation circuit, 27 ... Timing error processing circuit,
40, 49, 57 ... Averaging circuit, 41, 42, 48,
50, 58 ... Latch circuit, 43 ... Comparison circuit, 44,
60 ... Control signal generation circuit, 46, 52 ... Decode circuit, 45, 47 ... Counter circuit, 51 ... Subtraction circuit, 59 ... 3 input comparison circuit, 62 ... Micro tracking phase shift data Generation circuit, 68 ... CPU.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akifumi Miwabe 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Inside the Hitachi Media Visual Media Research Center (72) Inventor Yoshio Narita 1410 Inada, Katsuta-shi, Ibaraki Co., Ltd. Hitachi, Ltd. AV Equipment Business Division

Claims (5)

[Claims] 1. A helical scanning type magnetic recording wherein a rotary head scans a track obliquely formed on a tape as a recording medium by the rotary head at the time of recording so that the rotary head scans the recorded information at the time of reproducing. In a reproducing apparatus, a drum rotation control means for rotating a drum equipped with a rotary head at a predetermined rotation speed, a drum rotation phase detecting means for generating a rotation phase detection signal of the drum, and the tape recording during reproduction are recorded. A tape traveling control means for selectively controlling a first traveling speed different from the tape traveling speed at the time and a second traveling speed equal to the tape traveling speed at the time of recording; Tape traveling drive means for traveling the tape in accordance with the control signal of the traveling control means, and the envelope of the RF signal output from the rotary head during reproduction.
An envelope detection means for generating a reproduction detection signal, a reproduction timing signal generation means for generating reproduction timing information from the reproduction signal, a time difference or a phase difference between the drum rotation phase detection signal and the reproduction timing signal, When the timing time difference detecting means for generating the timing time difference signal and the tape running control means control the tape running speed at the first running speed, according to the timing time difference signal and the envelope detecting signal, A timing time difference reference value generating means for generating a predetermined timing time difference reference value; a timing error signal generating means for generating a timing error signal by comparing the timing time difference signal with the timing time difference reference value; -The tape traveling control means controls the tape traveling speed at the second traveling speed. In this case, the timing error signal is added to the tape running control signal which is the output of the tape running control means, and is returned to the tape running drive means. A helical scanning type magnetic recording / reproducing apparatus characterized by the above. 2. The helical scanning magnetic recording / reproducing apparatus according to claim 1, wherein the timing signal is a synchronizing signal of video information. 3. A helical scan type magnetic recording in which a rotary head scans a track obliquely formed on a tape which is a recording medium by the rotary head at the time of recording so that the rotary head scans the recorded information at the time of reproducing. In a reproducing apparatus, a drum rotation control means for rotating a drum equipped with a rotary head at a predetermined rotation speed, a drum rotation phase detecting means for generating a rotation phase detection signal of the drum, and the tape recording during reproduction are recorded. Tape traveling control means for controlling the traveling speed to be equal to the traveling speed of the tape, and tape traveling driving means for traveling the tape in accordance with the control signal of the tape traveling control means. Envelopment of the RF signal output from the rotary head during playback
And an envelope signal increase / decrease detecting unit for detecting an increase / decrease of the envelope signal using the envelope detection signal, and reproduction timing information from the reproduction signal. A reproduction timing signal generating means, a timing time difference detecting means for detecting a time difference or a phase difference between the drum rotation phase detection signal and the reproduction timing signal, and generating a timing time difference signal; and an envelope signal increase / decrease detecting means. A timing error signal is generated by comparing the timing time difference signal and the timing time difference reference value with a timing time difference reference value generating means for generating a predetermined timing time difference reference value using the timing time difference signal according to the detection signal. Timing error signal generating means for A timing error signal feedback means for adding a signal to the tape travel control signal which is the output of the tape travel control means and returning the signal to the tape travel drive means. Scanning magnetic recording / reproducing device. 4. The helical scanning type magnetic recording / reproducing apparatus according to claim 3, wherein a plurality of the rotary heads are provided on the circumference of the drum, and the increase / decrease detecting means for the envelope signal are the same rotary head. A magnetic recording / reproducing apparatus of the helical scanning type, which detects increase / decrease of the envelope signal which is the output of. 5. A helical scanning type magnetic recording wherein a rotary head scans a track obliquely formed on a tape as a recording medium by the rotary head at the time of recording so that the rotary head scans the recorded information at the time of reproducing. In a reproducing apparatus, a drum rotation control means for rotating a drum equipped with a rotary head at a predetermined rotation speed, a drum rotation phase detecting means for generating a rotation phase detection signal of the drum, and the tape recording during reproduction are recorded. Tape traveling control means for controlling the traveling speed to be equal to the traveling speed of the tape, and tape traveling driving means for traveling the tape in accordance with the control signal of the tape traveling control means. Envelopment of the RF signal output from the rotary head during playback
And an envelope signal increase / decrease detecting unit for detecting an increase / decrease of the envelope signal using the envelope detection signal, and reproduction timing information from the reproduction signal. Reproduction timing signal generating means, timing time difference detecting means for detecting a time difference or phase difference between the drum rotation phase detection signal and the reproduction timing signal, and generating a timing time difference signal, and timing for generating a predetermined timing time difference reference value Timing difference reference value generating means, timing time difference reference value changing means for increasing or decreasing the timing time difference reference value by a predetermined amount, and timing for generating a timing error signal by comparing the timing time difference signal with the timing time difference reference value. The error signal generating means and the timing error signal Signal is added to the tape running control signal which is the output of the tape running control means, and is fed back to the tape running drive means. A helical scanning type magnetic recording / reproducing apparatus characterized in that increase / decrease of the timing time difference reference value is controlled according to a detection signal of the means.