JPH087407A - Tracking controller - Google Patents

Abstract

PURPOSE:To prevent pseudo locking at the time of variable reproduction tracking by controlling the polarity of a tracking signal in accordance with the pull-in direction of a head scanning direction to a track for variable speed reproduction and the result of identification of the pilot signal frequency reproduced by a head just before the extreme proximity to this track. CONSTITUTION:A polarity discriminating means 33 detects the direction of the phase pull-in control by a track error detecting means 15, identifies the polarity of an error signal eN and outputs an identification signal eP of H when eN is positive and of L when negative. Namely, the identification signal eP of the H is outputted when the phase pull-in control by a means 15 for the track for variable speed reproduction is positive and of the L when negative. A frequency discriminating means 31 identifies the frequency of the reproduced pilot signal at the tracking error signal detection timing at the time the track imkmediate before one track of the track for variable speed reproduction is scanned by the head for detecting the tracking error signal. This means outputs an identification signal ef of L if this frequency is f1 and of H if f2. A timing signal generating means 32 outputs a signal ES for controlling the error signal polarity of a tracking error detecting circuit 18 according to signal eP, ef.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumer digital VTR for recording / reproducing a compressed video signal by using a rotary magnetic head, and in particular, information for variable speed reproduction at an arbitrary speed faster than normal reproduction is a rotary magnetic field. The present invention relates to a tracking control method suitable for performing variable speed reproduction of a magnetic tape recorded in a distributed manner at each track position according to a head scanning locus.

[0002]

2. Description of the Related Art For tracking control of a consumer digital VTR, a method disclosed in Japanese Patent Laid-Open No. 255969/1992 is adopted.

In this system, for example, a rotary magnetic head has 180
In the case of the one-channel configuration of the facing A and B, the frequency spectrum of the digital sum (integral value) of the recording digital signal by the head A is f1, f2 as shown in FIG.
Alternately recorded so that there is a dip in (f1 <f2), and the frequency spectrum by the head B has peaks at f1 or f2 respectively as in (b) and (c). Since it has been already described, it is omitted), and the 4-track completion system (F0 →
The recording track (F1 → F0 → F2) is formed, and the tracking control is performed by comparing the pilot signal crosstalk amounts of f1 and f2 from both adjacent tracks at the time of F0 track scanning by the head 2A during normal reproduction.

On the other hand, a consumer digital VTR uses an image compression technique to reduce the amount of data recorded on a magnetic tape. The so-called MPEG method is generally used as an example of the image compression technique.

In the MPEG system, since the video is constructed by utilizing the difference between the frames, the continuity of the data of the preceding and following frames is lost when the high speed reproduction is performed at a speed different from the normal reproduction. It is not possible to combine images from.

Therefore, as a variable speed reproducing method for a VTR utilizing image compression by the MPEG system, for example, "FIRS" is used.
T SCAN TECHNOLOGY FOR DIGITAL VIDEO TAPE RECORDERS
(IEE Transactions on Consumer Electronics Vol.3
9, No. 3, AUGUST 1993) ”has been proposed.

According to this method, in order to be able to decode an image even at the time of variable speed reproduction, the variable speed is set at a specific position on the magnetic tape which matches the scanning locus of the reproducing head according to the tape speed of the variable speed reproduction. Video data for reproduction is independently dispersed and recorded, which enables variable speed reproduction such as search and shuttle reproduction even on a tape compressed and recorded by the MPEG system.

FIG. 8 shows an example of a track pattern on the magnetic tape recorded by the above method at 9 times speed in the forward (forward) direction (head configuration is 180 ° facing A, B1 channel). . In the figure, 2A and 2B are reproducing heads, a shaded portion such as 50 is a recording area of video data for 9 × speed reproduction recorded by the head 2A, and a shaded portion such as 51 is a head. 2B
Recording area for 9x speed video data recorded in 5
Reference numeral 2 is a scanning locus of the rotary magnetic head 2A or 2B during normal reproduction, and 53-A, 53-B and 54-A and 54-B are images for reproduction at 9x speed by the heads 2A and 2B during 9x speed reproduction, respectively. A locus showing the state of scanning the data track,
Reference numerals 55 and 56 are scanning trajectories of the head during 9 × speed reproduction.

In 9 × speed reproduction, the head obliquely scans 9 tracks as shown by the loci 53 to 56 in FIG. Therefore, in order to perform 9 × speed reproduction, the data 50 and 51 for 9 × speed reproduction are appropriately divided and recorded at specific positions of tracks of the same head and azimuth in accordance with the scanning loci of the rotary magnetic heads 2A and 2B. It is something to keep.

Further, each track is composed of a plurality of data blocks of several hundred bytes, and in each data block, a track number and a block address including the block number are recorded together with the image data.

By the way, in the above method, since the video data for variable speed reproduction is recorded only on a specific track that matches the head scanning locus, it goes without saying that the normal reproduction state is changed to the variable speed reproduction. Alternatively, when changing the speed in a variable speed reproduction state, the scanning phase must be controlled so that the rotary magnetic head accurately scans a predetermined track on which video data is recorded.

In a consumer VTR or the like, the control of the scanning phase of the head with respect to the recording track is generally performed by relatively controlling the tape running speed (rotation speed of the capstan motor).

FIG. 9 shows a servo block structure of a capstan motor for performing variable speed reproduction of a tape recorded in the pattern shown in FIG. In the figure,
Reference numeral 1 is a magnetic tape, 2A and 2B are a pair of rotary magnetic heads provided facing each other by 180 °, 3 is a rotary drum, 4 and 5 are guide pins for tape running, and 6 is driven by a capstan motor 7. Capstan shaft, 8 is FG (tachogenerator) of capstan motor 7, 9 is pinch roller,
Reference numeral 10 is a capstan motor speed control circuit (high-speed traveling control means) for variable speed reproduction, 11 is an adder, 12 is a motor drive circuit, 13 is a reproduction amplifier for amplifying reproduction signals of the heads 2A and 2B, and 14 is signal processing. Reference numeral 15 is a track error detecting means, 16 is a system controlling means, 17 is a switching means, 18 is a tracking error detecting means comprising a tracking error detecting circuit 19 and a switching circuit 20, and 21 is a switching signal generating circuit for controlling the switching circuit 20. , 22 are output terminals.

In FIG. 9, the track error detecting means 15 is
For example, the block address of the reproduction data is detected from the reproduced data string, and this is compared with the block address table in which the desired variable speed reproduction data is recorded,
The deviation between the current scanning track and the desired variable speed reproduction track is calculated, and as shown in FIG. 10, an error signal of e _N having a polarity corresponding to the direction of the scanning track error and e _N corresponding to the error amount of the number of scanning tracks. Is configured to output.
In the positive polarity area of the error signal e _N , the scanning phase of the head with respect to the recording track of the variable speed reproduction data of FIG. 8 is on the left side of the drawing, that is, the scanning phase of the head is behind the desired track phase. On the contrary, the negative polarity region indicates that the scanning phase of the head is on the right side in the figure and the scanning phase of the head is advanced.

Further, the tracking error detection means 18 compares the crosstalk levels of the pilot signals f1 and f2 reproduced from both adjacent tracks when the head scans the F0 track as described above to generate the tracking error signal. To do.

FIG. 11 shows a specific configuration example of the tracking error detection circuit 19. In the figure, 23 and 24 are a pair of BPFs (bandpass filters) for extracting pilot signals of f1 and f2 from the head reproduction signal e _H , and 25 and 26 are peak detection of pilot signals extracted by the BPFs 23 and 24, respectively. And a pair of comparators 29 and 30 for comparing the outputs of the peak detectors 25 and 26 with positive and negative polarities.
Is an S / H (sample and hold) circuit.
In the case where the recording pattern of the variable speed reproduction data is as shown in FIG. 8, the tracking error is detected by appropriately selecting the timings at which the heads 2A and 2B scan the F0 track, but this is for simplicity. Head 2A
However, the tracking error detection is performed only on the track entry side in terms of scanning timing, and the operation timing is shown in FIG. In synchronization with the head switching signal, at each scanning start timing of the head 2A, that is, the head 2
The S / H circuits 29 and 30 are generated by the S / H pulse of (b) generated at the timing when A scans the track entry side.
Is driven, and the comparator 2 is driven as shown in FIGS.
Tracking error signal e of f1-f2 detected in step 7
And _T1, the tracking error signal e _T2 is outputted through the S / H circuit f2-f1 becomes detected by the comparator 28. Here, two types of error signals having different polarities f1-f2 and f2-f1 are generated in order to selectively control the error signals to obtain a unidirectional error signal. That is, the polarity of the error signal needs to be unidirectional in view of the polarity of the tracking servo, whereas in the tracking method as shown in FIG. 7, the comparison polarities of f1 and f2 are not uniquely determined, and the scanning F0 track is set. This is because it is necessary to change the comparison polarity accordingly. For example, in order to track the variable speed reproduction data track recorded as shown in FIG.
Since the arrangement of f1 and f2 on the track entry side is different between −A and 54-A, the polarity must be switched every time the head 2A rotates to detect the tracking error signal.

Further, the switching signal generating circuit 21 is controlled by the system control means 16, and in response to a control start command from the system control means 16, as shown in FIG. "H",
A control signal es that repeats "L" is generated, and the switching circuit 20 is controlled by this. The switching circuit 20 is configured so that the contact is connected to the H side in the drawing when the control signal es is “H” and connected to the L side when the es is “L”. When es is "H", the tracking error detection means 18 outputs an error signal having a polarity of f2-f1 as shown in FIG. is there.

The tracking control for variable speed reproduction by the apparatus shown in FIG. 9 will be described below.

When the variable speed reproduction command key (not shown) is operated by the user, the system control means 16 first recognizes this and the switching means 17 is moved so that the contact of the switching means 17 is at the position a in the figure. At the same time, the command speed for variable speed reproduction is identified and input to the speed control circuit 10.

As a result, the control of the rotation speed of the capstan motor 7 is started so that the tape reproduction speed becomes the variable speed reproduction speed designated by the system control means 16.
The tape speed is raised to a predetermined speed only by the speed control loop with the phase control inactive.

Next, when the tape traveling speed reaches a predetermined speed, the system control means 16 detects this from the frequency of the motor FG8 and outputs the contact point of the switching means 17 from a to b in the figure, that is, the output of the track error detecting means 15. Adder 11
The switching means 17 is controlled so as to be supplied to the. At this time, since the phase control was not in operation, at the moment when the contact point of the switching means 17 was switched to b in the figure, the scanning locus of the head was not scanning the recording track of the variable speed reproduction data shown in FIG. The track is not limited to the desired track.

Therefore, if the scanning locus of the head deviates from the desired track at the moment when the contact of the switching means 17 is switched to b, as shown in FIG. 10, the phase error signal corresponding to the amount and direction of this deviation. e _N is the track error detection means 1
Since it is input to the adder 11 from 5, the phase pull-in control starts so that this error signal becomes zero by the control of the phase control loop, that is, the head scans a desired track. Specifically, when the scan phase of the head is delayed with respect to the desired track and a positive error signal is output, the capstan motor, that is, the tape is accelerated and controlled by this error signal, and conversely, the negative polarity signal is output. When the error signal is output, the tape is decelerated and the head scanning phase is pulled to the target phase.

Next, when the head scanning phase reaches one track before the desired phase, the track error detection means 15 outputs this identification signal to the system control means 16, and when the system control means 16 recognizes this, the switching means 17 of the switching means 17 is detected. The switching means 17 is controlled so that the contact is switched from b to c, that is, the phase control signal to the adder 11 is switched from the output of the tracking error detecting means 15 to the output of the tracking error detecting means 18, and at the same time, the switching signal generating circuit 21 is controlled. Output the start command.

As a result, when the scanning phase of the head 2A at the time when the contact of the switching means 17 is switched to c is, for example, on the left side of one track in the figure with respect to the scanning locus 53-A of FIG. As shown in, the scanning timing of the head 2A in the first rotation from the time t ₀ is f2-f1.
The phase pull-in control is performed by the tracking error signal having the polarity of f.
With the polarity of 2, the control signal e of the switching signal generation circuit 21 will be used thereafter.
Since the polarity of the tracking error signal is sequentially switched by s, the scanning loci of the heads 2A and 2B sequentially scan the center of the track on which the desired variable speed reproduction data is recorded.

[0025]

By the way, in the above example, when the scanning phase of the head 2A at the time of control transition by the tracking error detecting means 18 is on the left side of one track in the figure with respect to the scanning locus 53-A of FIG. However, the timing is not always the case.

That is, the scanning phase of the head 2A at the start of control by the tracking error detecting means 18 may be close to the scanning locus 54-A of FIG. 8, for example, and in this case, f2-f1 as in FIG. When the tracking control is started from the error signal of the polarity, there is a problem that the head is pseudo-locked (erroneous tracking).

This point will be described below.

FIG. 13 shows the relationship of the tracking error signal with respect to the off-track of the head. T ₀
The error signal on the track is detected by comparing the crosstalk amounts of the pilot signals reproduced from the T _-1 and T ₁ tracks, and if the comparison polarity is f2-f1, then the characteristic (i) in the figure is obtained. When the head 2A is displaced to the left (phase lag), a positive signal is generated, and when the head 2A is displaced to the right (phase lead), an error signal corresponding to the negative displacement amount is generated. Further, in the F0 tracks of T _-2 and T ₂ which are adjacent to each other on both sides, the error signal polarity must be in one direction on the servo pole and therefore, as shown in (ii) and (iii), f1-f2 An error signal is generated with the polarity.

Now, assuming that the target scanning phase of the head 2A for variable speed reproduction is T ₀ track in the figure, when the scanning phase of the head 2A at the start of control of the tracking error detecting means is I in the figure. For example, if the tracking error signal is detected by selecting the polarity of f2-f1 as in the case of the characteristic (i), the positive error signal at the point a is supplied to the capstan motor and the motor, that is, the tape is accelerated, and the relative error is detected. Head 2
The phase of A advances and is drawn from point a to point b. However, when the reverse polarity of f1-f2 different from the original polarity is erroneously selected at the point I to detect the error signal, the polarity is inverted as shown by the characteristic of the broken line and the negative error signal at the point d is detected. As a result, the capstan motor is decelerated, that is, the control by the tracking error signal of the characteristic (ii) works, and the phase of the head 2A is delayed.
_-2 It will be pulled into the center point e of the track. Conversely, when the scanning phase of the head 2A at the start of control of the tracking error detecting means is II in the figure, the same is true. If the tracking error signal is detected with the polarity of f2-f1 at this point, the head 2A will be in the figure. Although it is possible to pull in from the point f to the point b, if the tracking error signal is erroneously detected with the polarities of f1-f2, the control according to the characteristic (iii) will work, and the head 2A will have the point g, that is, the point II '. Will be drawn to the position.

As described above, if the scanning phase of the head 2A at the start of control by the tracking error detecting means is not correctly identified and the polarity of the tracking error signal detection is not properly selected, the scanning phase of the head will eventually become As shown in 55 or 56 with respect to the desired scanning locus 53-A of 8, the left and right tracks are pseudo-locked to two tracks, that is, adjacent tracks on both sides, and there is a problem that high-speed reproduction data cannot be reproduced.

An object of the present invention is to solve the above-mentioned problems, and the polarity of detection of the tracking error signal at the start of control by the tracking error detecting means can be automatically and properly selected without being influenced by the scanning phase of the head. Therefore, the pseudo lock of tracking does not occur, and even if the pseudo lock occurs, this can be promptly avoided and the desired variable speed reproduction data can be accurately reproduced. To provide a tracking device capable of

[0032]

In order to achieve the above object, the present invention has, as a first configuration, a polarity determining means for determining the polarity of an error signal of a track error detecting means, and a track longitudinal direction for detecting a tracking error signal. At a specific position, the frequency discriminating means for discriminating the frequencies of the pilot signals f1 and f2 reproduced by the rotary magnetic head for generating the tracking error signal, and the discrimination results by the polarity discriminating means and the frequency discriminating means are discriminated and predetermined. Timing signal generating means for generating the timing signal of
The polarity of the tracking error detection is automatically determined based on the head phase pull-in direction by the tracking error detection means and the identification result of the pilot signal frequency reproduced by the head that detects the tracking error signal immediately before switching to the control by the tracking error detection means. I decided to do it.

Further, as a second structure, a tracking phase detecting means for detecting the tracking phase of the rotary magnetic head during tracking control by the tracking error detecting means, and a reference voltage applying means for applying a reference voltage to the output of the tracking error detecting means. And a control signal generating means for generating a control signal for selectively controlling the polarity of the error signal output of the tracking error detecting means, and the scanning phase of the head records variable speed reproduction information during tracking control by the tracking error detecting means. If there is a deviation from the track phase thus set, correction control is performed so as to forcibly pull in the desired scanning phase.

[0034]

In the first construction, the polarity discriminating means discriminates the direction of the phase pull-in control by the track error detecting means. That is, the direction is discriminated whether the phase pulling of the head by the track error detecting means to the variable speed reproducing track is performed by accelerating or decelerating the tape speed.

The frequency discriminating means detects the frequency of the reproduction pilot signal at the tracking error signal detection timing when the head for detecting the tracking error signal scans one track before the variable speed reproduction track,
It works to output an identification signal according to f1 and f2.

Further, in the timing signal generating means, the phase pull-in control by the track error detecting means is performed by accelerating the tape speed, and the discrimination result of the frequency discriminating means is f.
If it is 1, it is f1-f2, if it is f2, it is f2-f1, and conversely, the phase pull-in by the track error detecting means is performed by decelerating the tape speed, and the pilot signal is f1. In the case of f2-f1 and f2, the polarity of f1-f2 is used as a starting point, and thereafter, a timing signal for automatically switching the detection polarity of the tracking error is generated for each rotation cycle of the head.

As a result, when the control by the track error detecting means shifts to the control by the tracking error detecting means, it becomes possible to detect a tracking error signal having a proper polarity in terms of the polarity of the servo and prevent the pseudo lock of the head. You can

Further, in the second configuration, when the pseudo lock of the head occurs, the direction is identified by the tracking phase detecting means, and the head is controlled by the polarity switching control of the reference voltage applying means and the control signal generating means. Since the control works to forcibly pull in the scan phase to the target scan phase, it is possible to avoid the situation where the head scan phase is left in the pseudo lock state for a long time.

[0039]

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

FIG. 1 is a block diagram showing an embodiment of a tracking control device according to the first present invention. In the figure, 31 is a frequency discriminating means, 32 is a timing signal generating means, 33 is a polarity discriminating means, and the other parts denoted by the same reference numerals as in FIG. 9 are the same or equivalent parts, and their operations are also the same. is there.

The polarity discriminating means 33 is to detect the direction of the phase pull-in control due to the track error detection means 15 identifies the polarity of the error signal e _N shown in FIG. 10, e _N
Is H when the sign is positive, and L when the sign is negative.
Is output. That is, when the phase pull-in control by the track error detecting means 15 to the variable speed reproduction track is performed by accelerating the tape speed, the identification signal of H is output, and when it is performed by the deceleration control, the identification signal of L is output. ing.

The frequency discriminating means 31 discriminates the frequency of the reproduction pilot signal at the tracking error signal detection timing when the head for detecting the tracking error signal scans one track before the variable speed reproduction track. When the signal frequency is f1, L is output, and when it is f2, H identification signal ef is output. That is, when the scanning phase of the head 2A reaches one track before the desired phase by the phase pull-in control by the track error detecting means 15, the pilot signal frequency reproduced by the head 2A at the timing of tracking error detection is f1. To L, and if it is f2, an identification signal of H is output.

Further, the timing signal generating means 32 has an identification signal e from the polarity determining means 33 and the frequency determining means 31.
Based on p and ef, a control signal Es for selectively controlling the error signal polarity of the tracking error detection means 18 is output based on a control start command from the system control means 16. As shown in FIG. 2, the discrimination signal ep of the polarity discriminating means 33 is H, that is, the phase pull-in control by the track error detecting means 15 is performed by accelerating the tape speed, and the discrimination signal ef of the frequency discriminating means 31 is L ( When the pilot signal frequency is f1), Es is L and the tracking error signal polarity is f1-f2. When ef is H (pilot signal frequency is f2), Es is H and the tracking error signal polarity is f2. -Select f1. or,
On the contrary, the identification signal ep of the polarity determining means 33 is L, that is, the phase pull-in control by the track error detecting means 15 is performed by decelerating the tape speed, and the identification signal ef of the frequency determining means 31 is L (the pilot signal frequency is f1). If Es is H, the tracking error signal polarity is f2.
-F1 is selected, ef is H (the pilot signal frequency is f
In the case of 2), Es is set to L, the tracking error signal polarity is selected from f1 to f2, and the timing signal Es is automatically generated after the above timing signal as a starting point and the polarity inversion is automatically repeated for each rotation cycle of the head. ing.

Hereinafter, the frequency discriminating means 31, the timing signal generating means 32, and the polarity discriminating means 3 which are different from those in FIG. 9 will be described.
FIG. 9 shows the tracking control operation of the portion 3
Similarly to the above, a description will be given by taking an example of variable speed reproduction in the forward (forward) direction of 9 times speed.

In the variable speed reproduction operation, as in FIG. 9, when the scanning phase of the head 2A reaches one track before the track phase in which the variable speed reproduction data is recorded by the phase pull-in control by the track error detecting means 15. This identification signal is output from the track error detection means 15 to the system control means 16. When the system control means 16 recognizes this, the contact point of the switching means 17 is changed from b to c in the figure, that is, the phase control signal input to the adder 11 is input. The switching means 17 is controlled so as to switch from the tracking error detecting means 15 to the output of the tracking error detecting means 18, and at the same time, a control start command is outputted to the timing signal generating means 32. As a result, the phase control of the head is performed by the tracking error detecting means 18
The control switches to using the error signal of.

FIG. 3 shows how the phase of the head is pulled by the tracking error detecting means 18.

In the track arrangement shown in FIG. 3A, the head 2 is controlled by the phase error control by the track error detecting means 15.
As a case where A reaches one track before the scanning target F0 track, I and I'as shown by the broken lines in the figure
There are two ways. Here, since the variable speed reproduction in the forward direction is taken as an example, I is the track error detecting means 15
And I'corresponds to the case where the tape is pulled in by the tape acceleration control by I. Head 2
When A is at the position I, the identification signal ep of the polarity determining means 33 is H and the frequency determining means 3 as described above.
1 outputs the H identification signal ef because the head 2A scans the F2 track (pilot signal frequency is f2).
Further, when the head 2A is at the position I ', the identification signal of L for ep and L for ef is the timing signal generating means 32.
Will be output to.

In response to this, the timing signal generating means 32 outputs the H control signal Es as described above, that is, the error signal output polarity of the tracking error detecting means 18 is f2-f.
The switching circuit 20 is controlled to be 1. As a result, the head 2A is pulled in to the center of the F0 track, which is the target scanning track, from point a to point b or point c to point b by pull-in control according to the error signal characteristic of f2-f1.

Similarly, as shown in FIG. 3B, when the head 2A is at the position II in the track arrangement different from that shown in FIG. 3A, the identification signal ep of the polarity discriminating means 33 is H and the frequency is the same. The discriminating means 31 outputs the identification signal ef of L because the head 2A scans the F1 track (the pilot signal frequency is f1). When the head 2A is at the position II ', ep is L and ef is H. It becomes an identification signal. In response to this, the timing signal generation means 32 outputs the L control signal Es, that is, controls the switching circuit 20 so that the error signal output polarity of the tracking error detection means 18 becomes f1-f2. As a result, the head 2A performs the pull-in control according to the error signal characteristic of f1-f2, and the target scan track F0 is changed from point a'to point b'or point c'to point b '.
You will be pulled into the center of the truck.

FIG. 4 shows the aspect of the control signal Es output from the timing signal generating means 32 in response to the head switching signal. Starting from a time point to when switching to the phase control by the tracking error detecting means 18,
As shown in FIG. 3 (A), first, as in the case of FIG.
When is selected, L is selected at the next rotation, and when L is selected first as in the case of FIG. 3B, as shown in FIG. 3B, it is inverted to H at the next rotation, Thereafter, a timing signal for repeating this is generated for each rotation of the head.

As described above, in the embodiment of FIG. 1, the tracking error is detected by identifying the head scanning phase pull-in direction by the track error detecting means, and by also identifying the head scanning track position at the time of control transition by the tracking error detecting means. Since the detection polarity is selectively controlled, it is possible to always perform tracking error detection with an appropriate polarity without being influenced by the scanning phase of the head when the control is shifted by the tracking error detection means. The pseudo lock that has been a problem in the conventional device can be solved.

In the embodiment of FIG. 1, variable speed reproduction in the forward (forward) direction of 9 times speed is taken as an example, but this is not particularly limited, and variable speed reproduction at any speed or reverse (reverse). Needless to say, the same applies to variable speed reproduction in the reverse feed direction.

Further, although the embodiment has shown the construction in which the polarity discriminating means is provided independently, this is not particularly limited, and the track error detecting means may be provided with this function and omitted. It is easy to make various modifications without departing from the spirit of the present invention.

FIG. 5 is a block diagram showing an embodiment of the tracking control device according to the second present invention. In the figure, 34 is a tracking phase detecting means and 35 is an adder 3.
6 and a reference voltage applying unit 37 including a changeover switch 38 and a reference voltage source 37 including reference voltages 39 and 40,
Reference numeral 41 is a control signal generating means, and the other parts denoted by the same reference numerals as those in FIG. 9 indicate the same or equivalent parts, and their operations are also the same.

In this embodiment, when the pseudo lock of the head occurs, the tracking phase detecting means identifies the direction, and the reference voltage applying means determines a reference voltage having a polarity to escape the pseudo lock to the tracking error signal. At the same time as the time application, the polarity switching control of the output timing signal of the control signal generating means is performed to forcibly pull the head scanning phase to the target scanning phase.

The tracking phase detecting means 34 detects the shift of the head scanning phase with respect to the track on which the variable speed reproduction data is recorded, that is, the direction of the pseudo lock when the tracking error detecting means 18 controls the scanning phase of the head. Further, it is configured to output the identification signal Eq of H when the scanning phase of the head is behind the target track and L when the scanning phase of the head is ahead.

The reference voltage application means 35 has positive and negative reference voltage sources 39 and 40, and is controlled by the control signal Ec of the system control means 16 via the changeover switch 38 for a predetermined period of time. Is output to the adder 36, that is, a DC offset voltage is applied to the control signal output of the tracking error detecting means 18.

Further, the control signal generating means 41 is controlled by the system controlling means 16, and in response to a control start command from the system controlling means 16, the switching signal generating circuit 2 of FIG.
As in the case of 1, the control signal Ts that repeats "H" and "L" for each head revolution is generated in synchronization with the head switching signal as shown in FIG.
When the control signal Ec is input from 6, the polarity of the control signal is inverted and output.

Hereinafter, regarding the tracking control operation of the portion including the tracking phase detecting means 34, the reference voltage applying means 35, and the control signal generating means 41 having a different configuration from that of FIG. 9, a 9 × speed forward (forward feed) direction as in FIG. Variable speed reproduction will be described as an example.

In the variable speed reproduction operation, as in FIG. 9, when the scanning phase of the head 2A reaches one track before the track phase in which the variable speed reproduction data is recorded by the phase pull-in control by the track error detecting means 15. This identification signal is output from the track error detection means 15 to the system control means 16. When the system control means 16 recognizes this, the contact point of the switching means 17 is changed from b to c in the figure, that is, the phase control signal input to the adder 11 is input. At the same time as controlling the switching means 17 so as to switch from the tracking error detecting means 15 to the output of the tracking error detecting means 18, a control start command is outputted to the control signal generating means 41. As a result, the control signal generating means 41 generates a control signal Ts in which “H” and “L” are sequentially repeated for each rotation of the head in synchronization with the head switching signal, starting from time t ₀ , as in FIG. 12E. Then
The phase control of the head is switched to the control using the error signal of the tracking error detection means 18 whose polarity is selected by Ts.

Here, when the scanning phase of the head 2A at the time of control transfer by the tracking error detecting means 18 is one track left side or one track right side with respect to the scanning locus 53-A in FIG. , The phase pull-in control is performed by the tracking error signal of the polarity of f2-f1 at the scanning timing of the head 2A in the first rotation from the time t _0, and f1-f2 in the scanning of 54-A which is the next rotation. Control signal generating means 41 for each rotation of the head thereafter.
Since the polarity of the tracking error signal is sequentially switched by the control signal Ts, the scanning loci of the heads 2A and 2B sequentially scan the center of the track on which the desired variable speed reproduction data is recorded.

On the other hand, when the scanning phase of the head 2A at the time of control transition by the tracking error detecting means 18 is one track left side or one track right side with respect to the scanning locus 54-A in FIG. , As described above, f2-f1
When the tracking control is started from the error signal of the polarity of, the head is pseudo locked. That is, as shown by 55 or 56 with respect to the desired scanning locus 53-A in FIG. 8, the left and right adjacent tracks are pseudo-locked.

When the pseudo lock occurs, that is, when the variable speed reproduction data is not reproduced although the control is switched to the control by the tracking error detection means 18, the tracking phase detection means 34 detects this and the direction of the pseudo lock. And outputs the control signal Eq. Specifically, it has the same configuration as the track error detecting means 15, detects a block address of the reproduced data from the reproduced data string, and creates a block address table in which this and the desired variable speed reproduction data are recorded. Compared to the direction of the deviation,
When the scanning phase of the head lags the target track as 55 locus with respect to the desired scanning locus 53-A in FIG. 8, H identification signal Eq when it advances as shown by 56 locus. Is output.

When the identification signal Eq is output from the tracking phase detecting means 34, the system control means 16 recognizes this, and when Eq is H, the contact of the changeover switch 38 is changed to A → B → A in the figure, or , Eq is L, A →
As in C → A, the control signal Ec for instructing the polarity inversion of the control signal Ts of the control signal generating means 41 is output at the same time as switching for a predetermined time.

As a result, for example, Eq is H, that is, the head scanning phase is 2 with respect to the target track, as shown by the locus indicated by 55 for the desired scanning locus 53-A or 54-A in FIG.
If the track is delayed and the lock is pseudo, E
The contact of the changeover switch 38 is switched from A to B for a predetermined time by c, and a reference voltage source 39, that is, a positive DC offset voltage is input to the adder 36 for a predetermined time.
As a result, the capstan motor, that is, the tape is accelerated, and at the same time, the polarity of the control signal Ts of the control signal generating means 41 is inverted, and the tracking error signal polarities are f1-f2.
To f2-f1 or f2-f1 to f1-f2. That is, as shown in FIG. 13, T with the polarity of f1-f2
_{-When the} tape is pseudo-locked to two tracks, the tape is accelerated by applying a positive offset voltage,
Moreover, the polarities of tracking error detection are f1 to f2 to f2.
Since it is inverted to −f1, the head phase is pulled from the T ₋₂ track to the T ₀ track according to the tracking error characteristic of f2−f1. Further, in the state where the track is pseudo-locked to the T ₀ track, similarly, the tape is accelerated by applying a positive offset voltage, and the polarity of the tracking error detection is reversed from f2-f1 to f1-f2. The phase is pulled from the T ₀ track to the T ₂ track right by 2 tracks in accordance with the tracking error characteristic of f1-f2.

On the contrary, the identification signal Eq of the tracking phase detecting means 34 is L, that is, the head scanning phase is the target as shown by the locus 56 for the desired scanning locus 53-A or 54-A in FIG. When the track is advanced by two tracks and is pseudo-locked, the changeover switch 38 is activated by Ec.
Of the adder 3 switches from A to C for a predetermined time.
A reference voltage source 40, that is, a negative DC offset voltage is input to 6 for a predetermined time. As a result, the tape is decelerated, and at the same time, the control signal output T of the control signal generating means 41 is output.
The polarity of s is also inverted. That is, in the state where the tape is pseudo-locked to the T ₂ track with the polarity of f1-f2 as shown in FIG. 13, the tape is decelerated by applying the negative offset voltage, and the polarity of the tracking error detection is f1-f2.
The head phase is f2-f
According to the tracking error characteristic of 1, the track T ₂ to T ₀
To the track, and in the state where the pseudo locked to T ₀ track, similarly, the tape is decelerated and the polarity of the tracking error detection is inverted from f2-f1 to f1-f2 by the negative offset voltage is applied Therefore, the head phase is pulled from the T ₀ track to the T _-2 track left by 2 tracks in accordance with the tracking error characteristic of f1-f2.

As described above, the reference voltage applying means 35
The reason why the DC offset voltage is applied to the tracking control signal is to correctly guide the scanning phase of the head in the direction of avoiding the pseudo lock.
The values of 9 and 40 and the setting of the predetermined time for voltage application are appropriately set according to the characteristics of the capstan motor used, the characteristics of the servo system, and the like.

As described above, in the embodiment of FIG. 5, when the pseudo lock of the head occurs, the tracking phase detecting means identifies the direction and the reference voltage applying means escapes the pseudo lock to the tracking error signal. At the same time that the reference voltage of the polarity is applied for a predetermined time, the polarity switching control of the control signal output of the control signal generating means is performed to correct the head scanning phase to forcibly pull it to the target phase. It is not left in the time pseudo lock state.

In the embodiment of FIG. 5, variable speed reproduction in the forward (forward) direction of 9 × speed is taken as an example, but this is not particularly limited, and the first invention of the embodiment of FIG. It goes without saying that the same can be applied to variable speed reproduction at an arbitrary speed and variable speed reproduction in the reverse (reverse feed) direction in the same manner as. Further, the configuration is also shown in which the tracking phase detecting means is provided independently, but this is not particularly limited, and for example, the track error detecting means may be provided with this function and used also. Further, the reference voltage applying means is also constituted by the reference voltage source and the adder, but the present invention is not limited to this, and for example, the tracking error detecting means itself has a function of generating a DC offset voltage. It is easily possible, and various modifications can be easily made without changing the gist of the present invention.

[0070]

As described above, according to the present invention,
At the start of control by the tracking error detection means in the variable speed reproduction operation of the magnetic tape in which the information for the variable speed reproduction at an arbitrary speed faster than the normal reproduction is dispersed and recorded at each track position according to the scanning locus of the rotary magnetic head. The polarity of the tracking error signal detection can be properly and automatically selected without being influenced by the scanning phase of the head, so that the pseudo tracking lock of the head tracking by the tracking error detection means can be prevented.

Even if a pseudo lock occurs,
By detecting this and forcibly performing the pull-in correction control so that the head scanning phase tracks the original target track, the pseudo lock state does not last for a long time, and the desired variable speed reproduction It is possible to realize a tracking control device capable of accurately reproducing the data of 1.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a tracking control device according to the first present invention.

FIG. 2 is a diagram showing an error signal output polarity of a tracking error detecting means controlled by the timing signal generating means of FIG. 1 embodiment.

FIG. 3 is a diagram for explaining a head retracting operation by the tracking error detecting means of FIG. 1 embodiment.

FIG. 4 is a diagram showing a timing signal generated by the timing signal generating means of FIG. 1 embodiment.

FIG. 5 is a configuration diagram showing an embodiment of a tracking control device according to the second present invention.

FIG. 6 is a diagram illustrating a tracking method of a consumer digital VTR.

FIG. 7 is a diagram showing a recording pattern of a tracking signal of a consumer digital VTR.

FIG. 8 is a diagram showing an example of a recording pattern of variable speed reproduction information.

FIG. 9 is a diagram showing a conventional tracking control device.

FIG. 10 is a diagram showing an error signal output characteristic of the track error detecting means of the apparatus shown in FIG.

FIG. 11 is a diagram showing a specific configuration example of the tracking error detection means of the apparatus of FIG.

12 is a diagram for explaining the operation of the tracking error detection means in FIG.

FIG. 13 is a diagram illustrating a pseudo lock operation in conventional tracking control.

[Explanation of symbols]

 7 ... Capstan motor, 10 ... Speed control circuit, 15 ... Track error detection means, 16 ... System control means, 17 ... Switching means, 18 ... Tracking error detection means, 31 ... Frequency discrimination means, 32 ... Timing signal generation means, 33 ... Polarity determining means, 34 ... Tracking phase detecting means, 35 ... Reference voltage applying means, 41 ... Control signal generating means.

Claims (2)

[Claims] 1. The first and third tracks do not contain pilot signals, and the second and fourth tracks contain pilot signals of first and second specific frequencies, respectively. In the 4-track completion system of the fourth track, information for normal reproduction is sequentially recorded by forming oblique tracks on the magnetic tape, and a plurality of pieces of information for variable speed reproduction at an arbitrary speed faster than normal reproduction are recorded. What is claimed is: 1. A tape reproducing apparatus for reproducing magnetic tape recorded in a specific position on each track according to a scanning locus of a rotary magnetic head, the high-speed traveling control means for traveling the magnetic tape at a speed higher than a normal reproducing speed. And the scanning track position of the rotary magnetic head with respect to a predetermined track on which the variable speed reproduction information is recorded is identified, and the polarity is determined according to the scanning track error direction and the scanning track position is determined. A track error detecting means for outputting an error signal corresponding to click speed error amount, at the time of variable-speed playback, at least one of the rotary magnetic head is the first and third of said plurality of rotary magnetic heads
Of the first or third track, and at least one or more specific points in the longitudinal direction of the track, the first track is reproduced from both adjacent tracks. And a tracking error detecting means for comparing a crosstalk level of the pilot signal of the second frequency to generate an error signal for tracking, and at the time of variable speed reproduction of the magnetic tape, the magnetic tape is controlled by the high speed running control means. Is started up to a predetermined speed, the phase lead-in control of the rotary magnetic head to the track in which the variable speed reproduction information is recorded is performed based on the error signal of the track error detection means, and the rotary magnetic head is controlled. From the time when the scanning phase of the rotating magnetic head reaches within the close range of the target phase, based on the error signal of the tracking error detecting means, the rotating magnetic head is detected. In a tracking control device configured to perform tracking control of the tracking error, a polarity determination means for determining the polarity of the error signal of the track error detection means and a tracking error in a specific portion in the track longitudinal direction for detecting the tracking error signal. A frequency discriminating means for discriminating the frequencies of the first and second pilot signals reproduced by the rotary magnetic head for generating a signal, discriminating results by the polarity discriminating means and the frequency discriminating means, and discriminating a predetermined timing signal. And a timing signal generating means for generating the polarity of the error signal of the tracking error detecting means is automatically controlled by the timing signal generating means during tracking control of the rotary magnetic head by the tracking error detecting means in the variable speed reproducing operation. Selective control to prevent false tracking A tracking control device characterized by the above. 2. The first and third tracks do not contain pilot signals, and the second and fourth tracks contain pilot signals of first and second specific frequencies, respectively. In the 4-track completion system of the fourth track, information for normal reproduction is sequentially recorded by forming oblique tracks on the magnetic tape, and a plurality of pieces of information for variable speed reproduction at an arbitrary speed faster than normal reproduction are recorded. What is claimed is: 1. A tape reproducing apparatus for reproducing magnetic tape recorded in a specific position on each track according to a scanning locus of a rotary magnetic head, the high-speed traveling control means for traveling the magnetic tape at a speed higher than a normal reproducing speed. And the scanning track position of the rotary magnetic head with respect to a predetermined track on which the variable speed reproduction information is recorded is identified, and the polarity is determined according to the scanning track error direction and the scanning track position is determined. A track error detecting means for outputting an error signal corresponding to click speed error amount, at the time of variable-speed playback, at least one of the rotary magnetic head is the first and third of said plurality of rotary magnetic heads
Of the first or third track, and at least one or more specific points in the longitudinal direction of the track, the first track is reproduced from both adjacent tracks. And a tracking error detecting means for comparing a crosstalk level of the pilot signal of the second frequency to generate an error signal for tracking, and at the time of variable speed reproduction of the magnetic tape, the magnetic tape is controlled by the high speed running control means. Is started up to a predetermined speed, the phase lead-in control of the rotary magnetic head to the track in which the variable speed reproduction information is recorded is performed based on the error signal of the track error detection means, and the rotary magnetic head is controlled. From the time when the scanning phase of the rotating magnetic head reaches within the close range of the target phase, based on the error signal of the tracking error detecting means, the rotating magnetic head is detected. In a tracking control device configured to perform tracking control of a magnetic field, a tracking phase detecting means for detecting a tracking phase of the rotary magnetic head during tracking control by the tracking error detecting means, and a reference to the output of the tracking error detecting means A reference voltage applying means for applying a voltage and a control signal generating means for generating a control signal for selectively controlling the polarity of the error signal output of the tracking error detecting means are provided, and the tracking error detecting means in the variable speed reproducing operation is provided. In the tracking control of the rotary magnetic head, if the scanning phase of the rotary magnetic head is deviated from the track phase on which the variable speed reproduction information is recorded, the direction of the deviation is determined by the tracking phase detection means. Polarity reference voltage that detects and corrects this Is applied to the output of the tracking error detecting means for a predetermined time by the reference voltage applying means, and at the same time, the polarity of the control signal output from the control signal generating means is inverted.