JP3132687B2 - Magnetic playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order. BACKGROUND OF THE INVENTION Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1 to 5) Operation (FIGS. 1 to 5) Example (1) Recording Format (FIGS. 1 and 2) (2) Principle of tracking control (FIGS. 3 and 4) (3) Improvement of start-up characteristics (FIG. 5) (4) Configuration of video tape recorder (FIG. 6) (5) Effect of embodiment (6) Others Embodiment Effect of the Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic reproducing apparatus, and can be applied to, for example, a video tape recorder for recording and reproducing digital video signals.

[0003]

2. Description of the Related Art Conventionally, there is a video tape recorder which can convert a video signal into a digital signal (hereinafter referred to as a digital video signal) for recording and reproduction. That is, in the digital video signal, the image quality is not deteriorated even if the signal processing is repeated, so that the image quality of the reproduced image can be effectively prevented from being deteriorated even if dubbing is repeated many times by using a combination of error correction processing and the like.

[0004]

By the way, in this type of video tape recorder, if a recording track can be formed at a higher density, it is considered that the recording density of the whole can be improved accordingly. However, the tracking control applied to the conventional video tape recorder has a characteristic that it is difficult to perform high-accuracy tracking control, and when the recording tracks are formed at a high density, it is difficult to reliably perform the tracking control. is there.

That is, in the conventional tracking control, a control signal (CTL) is recorded on a control track formed in the longitudinal direction of the magnetic tape, and the tracking control is performed using the control signal (hereinafter referred to as the CTL system). ). That is, in the case of this method, in the video tape recorder, at the time of recording,
A control track is formed in the longitudinal direction of the magnetic tape, and a control signal whose signal level changes in synchronization with the rotation of the rotating drum is recorded on the control track. On the other hand, during playback, the video tape recorder obtains a phase comparison result between the control signal and a reference signal synchronized with the rotation of the rotating drum, and controls the phase of the capstan motor based on the phase comparison result. I do.

However, in the case of a magnetic tape, the recording position of the control signal and the recording track formed obliquely on the magnetic tape are affected by variations in tape tension during recording and reproduction, changes over time of the magnetic tape, changes in the magnetic tape running system, and the like. May change. Therefore, this CT
The L system has a characteristic that tracking control with high accuracy is difficult in the end, and when the recording tracks are formed at high density, it may become impossible to perform the just tracking.

On the other hand, in the conventional tracking control, there is a method in which a predetermined pilot signal is recorded in a recording track together with a video signal, and the tracking control is performed on the basis of the pilot signal.

That is, in this method, a low-frequency burst signal having a small azimuth loss is selected as a pilot signal, and at the time of recording, this pilot signal is recorded on a recording track. On the other hand, at the time of reproduction, in this tracking control, the signal level of the pilot signal leaking from adjacent tracks before and after is detected, and the phase of the capstan motor is controlled so that this signal level becomes the minimum.

However, in the case of this method, the position where the signal level of the pilot signal becomes the smallest and the optimum scanning position of the magnetic head (that is, a track center) may be deviated, for example, when the recording / reproducing efficiency of the magnetic head varies. In addition, if the recording tracks are formed at a high density, it is difficult to reliably perform the tracking control even in the case of this method.
Furthermore, in this method, if insert editing is repeated,
This shift is accumulated, and eventually there is a defect that the reproduced image is disturbed before and after the insert editing.

On the other hand, there is a method of detecting a signal level of a reproduced signal obtained from a recording track and performing tracking control so that the signal level becomes maximum. However, in this case, by detecting the signal level of the video signal, the signal level of the reproduction signal also changes due to a pattern or the like,
Eventually, there is a feature that tracking control with high accuracy is difficult.

Further, in the case of this method, the azimuth recording method is employed in the video tape recorder, so that when the track is off-tracked for one or more times, almost no reproduced signal can be detected, and the tracking control itself becomes difficult. Further, there is also a problem that it takes time to perform the just tracking even when the off track is not performed for one or more tracks.

The present invention has been made in view of the above points, and it is an object of the present invention to propose a magnetic reproducing apparatus capable of reliably performing tracking control even when a recording track is formed at a high density.

[0013]

According to a first aspect of the present invention, there is provided a recording track TA, TB, TC, T formed obliquely in the longitudinal direction of a magnetic tape 2.
In the magnetic reproducing apparatus 10 for reproducing a predetermined recording signal from D,..., A control signal CTL is obtained from a control track CTL formed in the longitudinal direction of the magnetic tape 2.
, And rotational phase reference information detecting means 4 which outputs rotational phase reference information FGNO which is reset by the control signal CTL and changes in value in accordance with the rotational phase of the capstan motor 22.
5, 46, 47, and tracking error information detecting means 28, 30, 32, 3 for detecting tracking error information.
Tracking error information correcting means 4 for correcting tracking error information based on 5, 36, 37, 38, 39, 40, 41, 44 and rotational phase reference information FGNO;
2, 51, and tracking error information correction means 42, 5
And a magnetic tape traveling system control means for controlling the traveling system of the magnetic tape 2 based on the correction result DP.

Further, in the second aspect, the rotational phase reference information detecting means 45, 46, 47 comprises a rotational frequency signal FG which varies according to the rotational frequency of the capstan motor 22.
1 is counted, reset by the control signal CTL, and the counting result is sequentially output as rotation phase reference information FGNO.
Detects the rotation phase reference information FGNO at a predetermined timing synchronized with the rotation of the rotating drum, and corrects the tracking error information based on the detection result.

Further, in the third invention, the magnetic tape 2
Records a predetermined pilot signal SP2 on the recording tracks TA, TB, TC, TD,..., And outputs tracking error information detecting means 28, 30, 32, 35, 36, 37,
38, 39, 40, 41, and 44 detect the pilot signal SP2 from the output signals SR of the magnetic heads A to D, and detect tracking error information based on the timing at which the pilot signal SP2 is detected.

Further, in the fourth invention, the magnetic tape 2
Record the first and second pilot signals SP1 and SP2 having a high frequency and a low frequency without suffering azimuth loss, respectively.
B, TC, TD,... And tracking error information detecting means 28, 30, 32, 35, 36, 37, 3
8, 39, 40, 41, and 44 generate tracking error information based on the timing at which the second pilot signal SP2 is reproduced and the reproduced signal level of the first pilot signal SP1.

[0017]

The rotation phase reference information FGNO, which is reset by the control signal CTL and changes in accordance with the rotation phase of the capstan motor 22, is obtained, and the tracking error information is corrected based on the rotation phase reference information FGNO. If the running system of the magnetic tape 2 is controlled in this way, correct tracking error information can be obtained even when the capstan phase servo is not stable, whereby the start-up characteristics can be improved.

Accordingly, the correct tracking error information can be obtained by detecting the rotation phase reference information FGNO at a predetermined timing synchronized with the rotation of the rotating drum and correcting the tracking error information based on the detection result. it can.

Further, a pilot signal SP2 is detected from the output signals SR of the magnetic heads A to D, and the pilot signal SP2 is detected.
Even if the tracking error information is detected based on the timing at which 2 is reproduced, correct tracking error information can be obtained before the capstan phase servo is stabilized.

Further, a first pilot signal SP1 having a high frequency receiving azimuth loss and a second pilot signal SP2 having a low frequency not receiving azimuth loss are recorded in recording tracks TA, TB, TC, TD,... Therefore, even when the tracking accuracy is improved, the rising characteristics can be improved.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

(1) Recording Format In FIG. 1, reference numeral 1 denotes a recording format of a video tape recorder to which the present invention is applied as a whole, and three recording tracks CUE, CTL, T in the longitudinal direction of the magnetic tape 2.
Form a CC.

In the recording track CUE formed above the magnetic tape 2, an audio signal of one channel is recorded in the form of an analog signal, whereby the audio signal can be reproduced even when the magnetic tape 2 is fast-forwarded. It has been made like that. On the other hand, in the recording tracks CTL and TCC formed on the lower side, a control signal and a time code signal are respectively recorded, whereby the time code signal is reproduced and used for editing processing and the like, and fast forward reproduction is performed. In such a case, the time code signal can be interpolated as necessary with reference to the control signal.

Further, in the recording format 1, recording tracks TA, TB, TC, TD,... Are sequentially formed diagonally in the center of the magnetic tape 2, and the recording tracks TA, TB, TC, TD,. The digital video signal is recorded in

At this time, in the recording format 1, recording tracks TA, TB, TC, TD,... Are sequentially formed in close proximity by a quarter pitch of 0.012 [mm], thereby forming the recording tracks TA. , TB, TC,
TD are formed at a high density so that a digital video signal can be recorded efficiently.

The recording tracks TA, TB, TC, TD,...
, The digital video signal is recorded using magnetic heads having positive and negative azimuth angles, respectively, so that the continuous recording tracks TA and TB,
TC and TD,... Are paired to form azimuth recording. Further, in the pair of recording tracks TA and TB, TC and TD,..., The scanning start end and the scanning end end are formed to substantially coincide with each other, and the respective recording tracks TA, TB, TC, TD,.
The recording area is divided in the longitudinal direction.

Each of the recording tracks TA, TB, T
In the central portion of C, TD,..., An audio signal recording area ARA is formed at the center position of each recording track, and four-channel audio signals are PCM-recorded in the audio signal recording area ARA. ing. Further, a video signal recording area ARV is formed at both ends of the audio signal recording area ARA with a predetermined recording area interposed therebetween, and a digital video signal is recorded in the video signal recording area ARV. I have.

In the recording area ARV of the video signal, one frame of the video signal is recorded by six recording tracks, and furthermore, the digital video signal and the audio signal adopt a class 4 partial response system. To be recorded.

As shown in FIG. 2, between the audio signal recording area ARA and the video signal recording area ARV,
First and second recording areas ARP1 and ARP2 are formed, and the first and second recording areas ARP1 and ARP2 are formed.
In this case, a pilot signal for tracking control is recorded.

Of these, the second recording area A on the scanning start end side
In RP2, a pair of recording tracks TA and T
A second pilot signal SP2 is recorded at a predetermined distance before and after two recording track periods with respect to B, TC and TD, and in this format, a burst having a frequency of 417 [kHz] which is hardly affected by azimuth loss is recorded. The signal is selected as the second pilot signal SP2. At this time, in the recording tracks TA and TB,
A second pilot signal SP2 extends in the longitudinal direction of the recording track.
Thus, even when the magnetic head scans across the recording tracks TA and TB during reproduction, the pilot signal SP2 without waveform distortion can be reproduced.

Further, in the second recording area ARP2, a burst signal (hereinafter referred to as a guard signal) having a large azimuth loss of 16 [MHz] is recorded in an area where the second pilot signal SP2 is not recorded. Signal recording area ARA and video signal storage area AR
V, and the second pilot signal SP2 is recorded separately from the adjacent track. As a result, in the second recording area ARP2, only the second pilot signal SP2 is applied to the area where the second pilot signal SP2 is recorded, even if the magnetic head is off-track and scanned in an area adjacent to the second pilot signal SP2. It is designed so that it can be reliably detected.

Accordingly, by recording the second pilot signal SP2 having almost no azimuth loss in two recording track periods, a pair of recording tracks TA, TB and TC are formed.
The second pilot signal SP2 can be reproduced even when the two magnetic heads are off track in the range of two tracks before and after the TD with respect to TD and TD. The second pilot signal SP2 can be detected. By the way, if two or more tracks are off-tracked, in this embodiment, 4
Since the second pilot signal can be reproduced from the recording track separated from the track, the second pilot signal can be detected even if any position on the magnetic tape is scanned.

Further, at this time, even when the guard signal is recorded and the magnetic head is scanned off the adjacent recording track with the magnetic head off track, only the second pilot signal SP2 can be detected, thereby causing harmful influence from the adjacent recording track. Signal leakage can be prevented, whereby the second pilot signal SP2 can be reliably detected only from the target track. In this embodiment, based on the reproduced signal of the second pilot signal SP2, It is made to track roughly.

In practice, in this type of video tape recorder, azimuth recording is performed to prevent signal leakage from an adjacent track.
Therefore, when tracking control is performed using a pilot signal having a high frequency, if one or more tracks are off-tracked, the pilot signal cannot be detected and tracking control becomes difficult.

On the other hand, when tracking control is performed using a pilot signal having a low frequency, there is no azimuth loss, so that the pilot signal can be detected even when the amount of off-track is large. There is a drawback that leakage from an adjacent recording track occurs, which makes it difficult to perform highly accurate tracking control.

In particular, when a video signal and an audio signal are recorded by applying a class 4 partial response as in this embodiment, a signal component having a low frequency may be recorded in the video signal and the audio signal. Leakage of signal components may also degrade tracking accuracy. However, as in this embodiment, a pilot signal having a low frequency is recorded in two track periods, and a guard signal is inserted between the adjacent recording track, the audio signal recording area ARA, and the video signal recording area ARV to form the second pilot signal. If the signal SP2 is separately recorded, leakage of signals from the adjacent recording track, the audio signal recording area ARA, and the video signal recording area ARV can be prevented, and the pilot signal can be detected even if the track is off track by one or more tracks. This makes it possible to easily and reliably perform tracking control. In addition, the time required for starting up for just tracking can be reduced.

Further, by performing tracking control in combination with the pilot signal SP1 recorded in the first recording area ARP1, tracking control can be performed with high accuracy. Further, since the pilot signal SP2 can be recorded so that the phases of the recording tracks TA and TB coincide with each other and a reproduced signal without waveform distortion can be output, the pilot signal SP2 can be detected more reliably and the tracking control can be performed accordingly. Accuracy can be improved.

In response to this, in the first recording area ARP1, the first pilot signal SP1 is provided for each track.
In the case of this format, a burst signal having a large azimuth loss and a frequency of 5 [MHz] is selected as the first pilot signal SP1. The first pilot signal SP1 is recorded for each recording track, so that the first pilot signal SP1 is recorded separately from an adjacent track.
In addition, the signal is recorded at a predetermined distance from the preceding and succeeding audio signal recording area ARA and the video signal recording area ARV. In this embodiment, a non-signal area is formed between each recording area ARA, ARV and the adjacent track. It has been made like that.

As a result, in the first pilot signal SP1, when the magnetic heads A to D are off-track and scanned, the signal level of the reproduced signal decreases in accordance with the off-track amount, and when the off-track amount becomes one track or more, It is made impossible to reproduce. As a result, in this format, the second pilot signal S
Coarsely adjust the tracking control based on the playback signal of P,
The tracking control can be finely adjusted on the basis of the reproduced signal of the first pilot signal SP1, so that the tracking control can be performed with high accuracy.

That is, the second pilot signal SP2 has a feature that the reproduced signal can be detected even if the track is off-track for one or more tracks due to the low frequency.
There is a feature that tracking accuracy is low. In contrast, the first
In the pilot signal, the tracking accuracy can be increased due to the high frequency, but the tracking control cannot be performed if one or more tracks are off-tracked.

Therefore, in this embodiment, the tracking control is roughly adjusted based on the second pilot signal SP, and the tracking control is finely adjusted based on the first pilot signal SP1, whereby the first and second tracking signals are finely adjusted. Of the pilot signals SP1 and SP2 of the present invention, so that the tracking control can be performed with high accuracy even if one or more tracks are off-tracked.

Further, at this time, in the video tape recorder, the first and second recording areas ARP1 and ARP2 are arranged before and after the audio signal recording area ARA, so that the center of each recording track is used as a reference. Thus, the tracking control can be performed, and thereby the tracking control can be performed with high accuracy.

In practice, when such pilot signals SP1 and SP2 are recorded at the scanning start end or the like and tracking control is performed, the pilot signal SP1 due to the expansion and contraction of the magnetic tape 2 in the longitudinal direction and the variation of the scanning angle between the devices, etc. And S
At the end opposite to the recording position of P2, there is a feature that the amount of off-track becomes large, and there is a problem that the CN ratio of the reproduced signal is largely deteriorated accordingly. However, if the pilot signals SP1 and SP2 are recorded substantially at the center position in the scanning direction as in this embodiment, the generation of a large off-track can be dispersed to the scanning start end side and the scanning end end side, and the CN of the reproduced signal can be dispersed. Significant deterioration of the ratio can be prevented.

(2) Principle of Tracking Control FIG. 3 shows the principle of tracking control according to the present invention.
Tracking control is performed so that the scanning locus SC coincides with the recording track T. In this case, in the video tape recorder, the track is off-track by a distance Tr in a direction orthogonal to the recording track T, and the position of the recording track T is controlled in the longitudinal direction of the magnetic tape 2 by controlling the magnetic tape traveling system.
It can be understood that just tracking can be performed for just tracking.

That is, in the tracking control, it is sufficient to control the magnetic tape traveling system so that the distance X becomes 0. In this embodiment, the distance X is set with reference to the second recording area ARP2. Is measured (that is, the time t is detected in this case), so that the tracking error amount is roughly detected. For this reason, in this embodiment, with reference to the drum PG signal PG whose signal level rises in synchronization with the rotation of the rotating drum, after this drum PG signal PG rises, the second pilot signal SP2 rises. Is detected at time t1.

In this case, when the magnetic head is accurately scanning the recording track, the second pilot signal SP2 is passed after a predetermined period t2 with respect to the drum PG signal PG.
Rises, it is understood that the time difference t between the times t1 and t2 is proportional to the off-track amount Tr. However, in the pilot signal SP2 having such a low frequency, the off-track amount cannot be detected with high accuracy when the off-track amount is detected by time measurement because the period of the signal itself is long. .

For this reason, the second pilot signal SP2 is used for rough tracking control by making use of the feature that the amount of off-track can be detected even if it is offset by one or more tracks, and the amount of off-track is finely controlled by the first pilot signal SP1. adjust.

That is, as shown in FIG. 4, in the first pilot signal SP1, a signal having a large azimuth loss is recorded in a burst form for each track, so that even when the track is slightly off track from the track center TC, the signal is reproduced. There is a feature that the signal level of the signal SR sharply decreases. As a result, as shown by the arrow a, the magnetic tape traveling system is controlled so as to offtrack in a minute range, and the arrow b
When the signal level suddenly drops as shown by c and c,
The tracking control can be performed with high accuracy by judging off-tracking and controlling the magnetic tape running system.

By the way, a conventional video tape recorder (a video tape recorder having a magnetic tape width of 8 mm).
In this case, as in this embodiment, a method of detecting the signal level of the pilot signal and performing tracking control is used. However, this conventional tracking control is characterized in that tracking control is performed by detecting leakage from an adjacent track, and there is a feature that highly accurate tracking control as in this embodiment is difficult.

Thus, the second pilot signal having no azimuth loss and the first pilot signal having a large azimuth loss are recorded, the off-track is roughly corrected by the second pilot signal, and the off-track is corrected by the first pilot signal. By finely adjusting the tracking, the tracking control can be performed with high accuracy, whereby the tracking control can be reliably performed even when the recording tracks are formed at a high density.

(3) Improvement of Rising Characteristics By the way, in the method of performing tracking control by detecting the timing of the second pilot signal SP2, if the running speed of the magnetic tape 2 changes, a correct tracking error is generated. There is a feature that the amount cannot be detected.

That is, according to the time measurement result of the second pilot signal SP2, the tracking error is detected as correct tracking error information only after the running speed of the magnetic tape 2 is maintained at a constant value. In this case, tracking control cannot be performed stably unless the capstan phase servo rises and becomes stable. Therefore, in this type of tracking control,
There is a disadvantage that the response characteristic when the running speed of the magnetic tape 2 is switched is deteriorated, and there is a disadvantage that the tracking accuracy when the reproduction speed is changed at the start of reproduction is deteriorated accordingly.

Therefore, in this embodiment, the rotational phase of the capstan motor is detected with reference to the control signal CTL, and the tracking error information is corrected based on the change in the rotational phase. The rising characteristics when the running speed is switched are improved.

[0054] That is, as shown in FIG. 5, capstan phase after the servo is connexion stable rising, the second pilot signal S with respect to a predetermined reference phase TP ₀
By detecting the P2, deviation TPT of pilot signal detection timing TP1 from the reference phase TP ₀ is to represent the tracking error amount may be controlled with a magnetic tape running system in accordance with the deviation TPT (FIG 5
(A)).

However, the timing TP2 of the pilot signal SP2 detected when the capstan phase servo has not risen also includes a deviation of the capstan phase servo. In this case, it is difficult to correctly detect the tracking error information. become. In this case, the control signal CTL is output at a timing CTL2 which is shifted by a shift of the capstan phase servo from the timing CTL1 of the control signal CTL obtained when the capstan phase servo rises and is stabilized. Is equal to the reference phase CTL1, it means that the capstan phase servo has risen and is stable.

Accordingly, if the phase shift of the timing CTL2 with respect to the reference phase CTL1 is detected and the shift TPT is corrected based on the detected result, the tracking control is performed toward the final control target before the capstan phase servo rises. And the rising characteristics can be improved.

However, since the control signal cannot be obtained at a constant period at the time of rising, there is a characteristic that the phase shift of the timing CTL2 with respect to the reference phase CTL1 cannot be detected by directly using the control signal. Therefore, in this embodiment, the rotation frequency signal of the capstan motor is counted by a counter, and the counter is reset at the timing when the control signal CTL rises, thereby generating a reference count signal FGNO for detecting the rotation phase. (Figure 5
(B)).

Further, by taking in the reference count signal FGNO at the timing of the reference phase CTL1, the phase shift of the timing CTL2 with respect to the reference phase CTL1 is detected, and the tracking error information is corrected based on the detection result.

(4) Configuration of Video Tape Recorder In an actual video tape recorder, tracking control is performed using a tracking servo circuit 10 having the configuration shown in FIG. That is, in a video tape recorder,
By switching and using a plurality of magnetic heads A to D arranged on a rotating drum, a video signal and an audio signal are recorded in accordance with the above-described recording format.

On the other hand, the tracking servo circuit 10
Drives the capstan motor 22 with a predetermined speed control circuit (not shown).
Is driven at a predetermined rotation speed. Further, the tracking servo circuit 10 amplifies the reproduction signal SR output from the magnetic heads A to D by the reproduction amplifier circuit 28 and outputs the amplified signal to the timing pulse generation circuit 30 and the maximum value detection circuit 32.

Here, the timing pulse generation circuit 30
The second pilot signal SP2 is output from the bandpass filter circuit.
Is extracted and subjected to envelope detection, whereby the signal level of the second pilot signal SP2 is detected.
Further, the timing pulse generation circuit 30 supplies the envelope detection output to the comparison circuit, and obtains a comparison result with a predetermined reference level, thereby obtaining the second pilot signal S.
The rising of P2 is detected.

The drum motor 34 drives the rotary drum to rotate at a predetermined rotation speed. At this time, a rotation frequency signal FG and a rotation phase signal PG whose signal levels change according to the rotation speed and the rotation phase are respectively output to an FG generator 35. And a PG generator 36. The FG selection circuit 39 includes the amplification circuit 3
The rotation frequency signal FG and the rotation phase signal PG are fetched via 7 and 38, thereby outputting a drum PG signal PG rising at a predetermined timing in synchronization with the rotation of the rotating drum.

The interval measurement counter circuit 40 includes a drum PG
After the operation of the counter is started at the rising edge of the signal PG, the counting operation is controlled to stop at the rising edge of the second pilot signal SP2 based on the detection result of the timing pulse generating circuit 30, whereby the second pilot signal S
The rise of P2 is timed. Further, the interval measurement counter circuit 40 outputs the count result to the subtraction circuit 41, obtains a comparison result with a predetermined reference value REF, and outputs the comparison result to the addition circuit 44 via the subtraction circuit 42.

As a result, in the tracking servo circuit 10, the output signal of the adding circuit 44 is added to the speed control information of the speed control circuit, and the capstan motor 22 is driven based on the result of the addition. The tracking control is roughly performed on the basis of the pilot signal SP2.

On the other hand, the maximum value detection circuit 32 extracts the signal component of the first pilot signal SP1 by a band-pass filter circuit and performs envelope detection.
The signal level of the pilot signal SP1 is detected. Further, the maximum value detection circuit 32 obtains a comparison result between the envelope detection output and the envelope detection output one cycle before stored in a predetermined memory means, thereby detecting an increase or decrease in the signal level of the first pilot signal SP1. Then, phase control information is output based on the detection result.

Thus, in the tracking servo circuit 10, the addition circuit 44 adds this phase control information to the output signal of the subtraction circuit 42, and drives the capstan motor 22 with the added signal obtained as a result. The tracking is finely controlled with reference to the first pilot signal SP1. Further, in the tracking servo circuit 10, the FG detector 45 generates a rotation frequency signal FG1 of the capstan motor 22, and based on the rotation frequency signal FG1, a reference count signal FGNO.
Generate

That is, in the tracking servo circuit 10, the rotation frequency signal FG 1 is supplied to the FG counter 47 via the amplifier circuit 46, and the control signal CTL output from the control head 48 via the amplifier circuit 49 is supplied to the FG counter 47. Give to. This gives F
The G counter 47 counts the rotation frequency signal FG1 based on the control signal CTL, and outputs the count result to the numerical value conversion circuit 51.

Here, the numerical value conversion circuit 51 fetches the count result based on the reference phase signal RCTL synchronized with the rotation of the rotating drum, and then detects the result of comparison between the count value and the reference value in the steady state. In addition, numerical conversion circuit 5
1 detects a change in the comparison result, and thereby detects a displacement of the capstan phase servo included in the count result of the interval measurement counter circuit 40.

Further, when this deviation amount is detected, the numerical value conversion circuit 51 converts this deviation amount into a phase correction value,
Output to the subtraction circuit 41, where the interval measurement counter circuit 4
Subtract from the count result of 0. Accordingly, in the tracking servo circuit 10, when the capstan phase servo is not started, the count result of the interval measurement counter circuit 40 is corrected based on the correction value output from the numerical value conversion circuit 51, and the tracking The rising characteristic is improved by correcting the king error information. On the other hand, when the capstan phase servo rises, the tracking servo circuit 10 performs tracking based on the count result of the interval measurement counter circuit 40 because the correction value output from the numerical value conversion circuit 51 converges to 0. Can be controlled.

(5) Effects of the Embodiment According to the above configuration, when the first pilot signal having a large azimuth loss and the second pilot signal having no azimuth loss are recorded to improve the tracking accuracy, the capacities are improved. A reference count signal FGNO is generated based on the rotation frequency signal of the stun motor, and the reference count signal FGN is generated.
By correcting the tracking error information based on O, the tracking accuracy can be improved, and the rise characteristics can be improved.

(6) Other Embodiments In the above-described embodiment, the case where the tracking control is performed using the first and second pilot signals has been described. However, the present invention is not limited to this, and various tracking control may be performed. In combination with the method, the rising characteristics can be improved.

Further, in the above embodiment, the class 4
The case where the digital video signal is recorded / reproduced by applying the partial response has been described. However, the present invention is not limited to this. When the digital video signal is recorded / reproduced by applying various recording methods, the digital video signal is further reproduced. The present invention can be widely applied to magnetic reproducing devices for recording and reproducing digital signals other than the above.

[0073]

As described above, according to the present invention, rotation phase reference information whose value changes in accordance with the rotation phase of the capstan motor is generated based on the control signal, and based on this rotation phase reference information. By correcting the tracking error information and performing tracking control, it is possible to obtain correct tracking error information even before the capstan phase servo is unstable, thereby obtaining a magnetic reproducing apparatus with improved start-up characteristics. it can.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a recording format of a video tape recorder according to one embodiment of the present invention.

FIG. 2 is a schematic diagram showing a detailed configuration thereof.

FIG. 3 is a schematic diagram for explaining a tracking servo using the second pilot signal.

FIG. 4 is a schematic diagram for explaining a tracking servo using the first pilot signal.

FIG. 5 is a schematic diagram for explanation for improving a rising characteristic;

FIG. 6 is a block diagram showing a video tape recorder to which the tracking servo is applied.

[Explanation of symbols]

2 ... magnetic tape, 10 ... tracking servo circuit,
22 Capstan motor, 30 Timing pulse generation circuit, 32 Maximum value detection circuit, 40 Interval measurement counter circuit, 47 FG counter circuit, 51
Numerical conversion circuit, A to D ... magnetic head, TA to TD ...
Recording track, SP1, SP2 ... Pilot signal.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 15/467

Claims (4)

(57) [Claims] 1. A magnetic reproducing apparatus for reproducing a predetermined recording signal from a recording track formed obliquely in the longitudinal direction of a magnetic tape. A control for reproducing a control signal from a control track formed in the longitudinal direction of the magnetic tape. Signal reproduction means; rotation phase reference information detection means for outputting rotation phase reference information that is reset by the control signal and changes in value in accordance with the rotation phase of the capstan motor; and tracking for detecting tracking error information. King error information detecting means, tracking error information correcting means for correcting the tracking error information based on the rotation phase reference information, and a correction of the magnetic tape based on a correction result of the tracking error information correcting means. Magnetic tape running system control means for controlling the running system. Magnetic reproducing apparatus according to symptoms. 2. The rotation phase reference information detecting means counts a rotation frequency signal that changes according to the rotation frequency of the capstan motor, is reset by the control signal, and sequentially counts the rotation result. The tracking error information correction means detects the rotation phase reference information at a predetermined timing synchronized with the rotation of the rotary drum, and corrects the tracking error information based on the detection result. The magnetic reproducing apparatus according to claim 1, wherein: 3. The magnetic tape records a predetermined pilot signal on the recording track. The tracking error information detecting means detects the pilot signal from the output signal of the magnetic head, and the pilot signal is 3. The magnetic reproducing apparatus according to claim 2, wherein the tracking error information is detected based on a detected timing. 4. The magnetic tape records a first pilot signal having a high frequency receiving azimuth loss and a second pilot signal having a low frequency not receiving azimuth loss on the recording track. The information detecting means generates the tracking error information based on a timing at which the second pilot signal is reproduced and a reproduction signal level of the first pilot signal. The magnetic reproducing device according to claim 2.