JPS61188767A - Tracking control device - Google Patents

Abstract

PURPOSE:To simplify a constitution compared with the system to use four cycle pilot signals by only recording two kinds of signals for the pilot signal and preventing the necessity of a switch control circuit or reference pilot signal by only one reference pilot signal at the time of reproduction. CONSTITUTION:By heads HA and TB, a video signal is alternately formed and recorded as tracks TA and TB for one field each, and at the first half of a track TA and the last half of a track TB, the pilot signal of the frequency (fa) and the pilot signal of the frequency (fb) are respectively alternately superimposed to the video signal as shown by giving the slanting line and the frequency is multiply recorded. At such a case, the right and left relation of the frequency of the pilot signal recorded at the track adjoining on both sides of the track TA, and the right and left relation of the frequency of the pilot signal recorded at the track adjoining on both sides of the track TB are recorded so that they may be reverse. At the time of reproduction, the pilot signal of the first frequency (fa) and the pilot signal of the second frequency (fb) are used and the tracking is controlled.

Description

[Detailed description of the invention] The invention will be explained in the following order.

A. Field of industrial application B. Overview of the invention C. Prior art D. Problems to be solved by the invention E. Means for solving the problems F. Effect G. Example G1. Description of recording pilot signals for tracking (Part 1) (Figures 1 to 3) Explanation of truck leg control during G2 regeneration (Figures 1 and 4) Explanation of increase in G3 phase lock point (Figures 1 and 5) H effect A Industrial application field The present invention relates to a tracking control device for a rotary head of a recording/reproducing apparatus such as a VTR or an audio tape recorder using a rotary head.

B. Summary of the Invention The present invention is a rotary head type recording and reproducing device in which tracking control is performed using only the rotary head for recording and reproducing information signals. In other words, the information signal recording track is divided into two, and pilot signals of two frequencies are alternately recorded on the first half of the information signal on every other track, and pilot signals of two frequencies are recorded on the remaining every other track. The information signal is superimposed on the latter half, and the pilot signals of the two frequencies mentioned above are recorded alternately, and during playback, tracking control is performed using the playback output of these two viroft signals from the rotating head. Two types of pilot signal frequencies are required, a tracking error signal can be obtained without time management, and signal processing is simple.

C Conventional technology In popular home VTRs, when performing tracking control in which the rotary head correctly scans the recording track during playback, conventionally a fixed magnetic head is used to perform control signal tracks formed in the longitudinal direction of the tape. This is done using the playback control signal from. However, the method of using such a fixed magnetic head is disadvantageous because the width of the tape becomes wider and when it is desired to downsize the recording/reproducing apparatus, the fixed head cannot be installed due to the location.

Therefore, various methods of tracking control without using such a fixed head have been proposed.

One method is to use a rotary head to record a low-frequency pilot signal for tracking on the track where the video signal is recorded, superimposed on the track for recording the video signal, as described in, for example, Japanese Patent Laid-Open No. 59-65962. During playback, tracking servo is performed by detecting the amount of crosstalk of this pilot signal from adjacent tracks. For this reason, the pilot signal is frequency-multiplexed so that it can be easily separated during playback as a low-frequency signal in the frequency spectrum where there is no recorded video signal, and the azimuth loss eliminates much crosstalk. The frequency is selected to be so low that it cannot be used.

First, an overview of this tracking control method will be explained.

In this example, pilot signals of four different frequencies are cyclically and sequentially frequency-multiplexed recorded on diagonal tracks.

For example, two rotating heads H with different azimuth angles
When recording is performed using a rotary head device in which A and HB are arranged 180° apart, these two are used to sequentially form recording tracks in a so-called overwriting state, as shown in Fig. 6. Four different frequencies f1. f2. f3. f4
The four pilot signals of
It is changed for each track of each book and recorded cyclically.

That is, as shown in FIG. 6, every other track T□, Tl is formed by one rotary head HA, and the FM
While the modulated video signal is recorded, the track T
A pilot signal of frequency f1 is recorded in □, and a pilot signal of frequency 13 is recorded in track T3 in a superimposed manner.

Also, the other rotary head HB rotates every other track T2. T4 are sequentially formed and an FM modulated video signal is recorded, and a pilot signal of frequency f2 is superimposed on track T2, and a pilot signal of frequency f4 is recorded on track T4, respectively.

By repeatedly recording these tracks T1 to T4, pilot signals of four types of frequencies are also sequentially and cyclically recorded to these tracks T1 to T4.

Tracking control during playback is performed as follows.

In this case, the head HA is in a just tracking state when it correctly scans tracks T1 and T3, and the head HB is in a just tracking state when it correctly scans tracks T2 and T4. Therefore, assuming that the gap width of the heads HA and HB matches the track width, the heads HA and HB are connected to the track T1.
- When sequentially scanning T4, signals P1 to P4 having the same frequencies f1 to r4 as the viroft signal frequency recorded on each track as a reference pilot signal are supplied to a multiplication circuit to calculate the frequency difference with the reproduced pilot signal. When detected, no frequency difference can be obtained in the just tracking state.

On the other hand, the tracking position is the head position (
This is for head HA) If there is a deviation as shown in (1) and (2), a pilot signal with a frequency different from the reference pilot signal from the adjacent track will be obtained as crosstalk, so the crosstalk will be A frequency difference occurs between the signal and the signal, and the level is proportional to the amount of difference.

Therefore, the frequencies f1 to f are set so that the frequency difference between tracks T1 and T1 and between tracks T2 and T4 is the same in the direction of deviation.
By selecting 4, tracking servo can be easily performed. That is, AfA=l fl T2
l=l T3 T41ΔfB-lf2-T31=l
Make it so that f+-ft l. In this way, the existence of the frequency difference ΔfA means a shift to the right with respect to the head HA, a shift to the left with respect to the head HB, and the frequency difference Δf
The presence of B means a shift to the left with respect to the head HA, and a shift to the right with respect to the head HB. In other words, the directions of deviations implied by the differences Δf^ and ΔfB are opposite between the heads HA and HB. However, the levels of the differences Δf^ and ΔfB are proportional to the amount of deviation.

From the above, in principle, these frequency differences ΔfA.

ΔfB indicates the amount of tracking error, and if this is controlled to become zero, just tracking can be achieved.

However, in the case of so-called overwriting, the head gap width is larger than the track pitch, so the solid line (3
), the just tracking state is a state in which the tracks on both sides of the original track to be scanned are scanned by slightly the same amount. That is, just tracking occurs when the levels of the frequency difference Δf^ and ΔfB are equal, and tracking control is performed by controlling so that the level difference between the difference Δf^ and 8fH becomes zero.

FIG. 7 is a block diagram of an example of the tracking control device.

This example is for an 8 mm video, where the pilot signal is a signal that is even lower than the band of the low-pass conversion carrier color signal, and the four frequencies f, f2, fg, and T4 are, for example, f L = 102 kHz. , −f 2 = 116
kHz.

f 3 = 160k)! z, f4 = 146
kHz, ΔfA”= 14kHz, Δf
It is assumed that a = 44kHz.

In FIG. 7, the playback outputs of heads HA and HB are rotary transformers (IIA) and (IIB), respectively.
), are supplied to the switch circuit (13) via the head amplifiers (12A) and (12B), respectively, and are connected to the terminal (14).
This switch circuit (13) is controlled by the head switching signal RFSW (Fig. 8A) through the head/node HA, HB.
In synchronization with the rotation of the tape, the heads HA or HB are alternately switched to one terminal and the other terminal for a period corresponding to a 180° angular interval in which the heads HA or HB scan the tape. Therefore, the output of the amplifier (15) is a signal in which the reproduction outputs of the heads HA and HB are continuously connected, and this signal is supplied to the reproduction signal processing system through the terminal (16).

The output of the amplifier (15) is also passed through a low-pass filter (2
1) and a pilot signal is extracted from the reproduced signal. The reproduced pilot signal from this low-pass filter (21) is supplied to a multiplication circuit (22).

On the other hand, a pilot signal generation circuit (23) is provided, from which reference pilot signals PL, P2 . P3. P4 are obtained and these are supplied to the switch circuit (24).

This switch circuit (24) includes a switch control circuit (20
) from the switch circuit (2
4). Switch control circuit (2
0) is the head switching signal RFS from the terminal (14).
W is supplied, and at the rising and falling points of this signal RFSW, the select signal SL! and SL2 are changed, and the reference pilot signal obtained from the switch circuit (24) is changed. For example, during the 180° period when the head HA scans the track T1, the switch control circuit (24) outputs the signal P1 with the frequency f1 as a reference pilot signal, and the -1 node HB scans the l/rack T2 during the 180° period. During the period, the signal P2 of frequency f1 is...
The four frequency signals 21 to P4 are sequentially switched (η) as shown in Fig. 8B.
).

A reference pilot signal from this switch circuit (24) is supplied to a multiplication circuit (22). Therefore, from this multiplication circuit (22), signals with frequencies ΔfA and ΔfB, which are the difference between the reference viroft signal and the regenerated pilot signal, are obtained, and these are extracted by bandpass filters (25) and (26), respectively, and detected. Circuit (27
) and (28) to produce DC level outputs SA and SB.

Here, the gains of the bandpass filters (25) and (26) are made equal to each other.

Detection outputs SA and SB of detection circuits (27) and (28)
are levels proportional to the amount of the frequency difference Δr^ and ΔfB components, that is, the magnitude of the pilot signal included as crosstalk in the reproduced pilot signal,
This corresponds to the tracking amount of the right and left adjacent tracks.

These detection outputs SA and SB are supplied to a subtraction circuit (29), from which a subtraction output SD of both is obtained. This subtraction output SD is a signal indicating which side is more shifted, left or right, but as mentioned above, the frequency difference ΔfA
and ΔfB, the directions of deviation are opposite when the head HA scans and when the head HB scans.

Therefore, the output SD of the subtraction circuit (29) is supplied as is to one input terminal of the switch circuit (30), and its polarity is inverted via the polarity inverting circuit (31) to the other terminal of the switch circuit (30). supplied to

Then, as this switch circuit (30) is alternately switched by the head switching signal RFS- when the head HA is scanning and when the head HB is scanning, the amplifier (32) detects a tracking error according to the direction of deviation. A voltage SE is obtained. Therefore, if this is supplied to the capstan motor, tracking control will be performed.

For example, when the head HA is in a scanning state shifted to the right as shown in position (2) in FIG. 6, the reproduced pilot signal from the low-pass filter (21) is
As shown in FIG. 6, the pilot signal of the adjacent truck on the right is also included. Then, as shown in Figure 8, the multiplication circuit (22) alternately obtains frequency differences Δf^ and ΔfB indicating a right shift for the heads HA and HB in each scanning period. Therefore, the output SA of the detection circuit (27) becomes as shown in FIG. E, the output SB of the detection circuit (28) becomes as shown in FIG. F, and the subtraction output SD becomes as shown in FIG. Then, the tracking error signal SE enters a state indicating a right-shift error, as shown in H in the figure.

In the case of Fig. 7, the order of the pilot signal from the switch circuit (24) is expressed as frequency f□-"2-f]-f
4-f□-... Since it was changed cyclically,
Although an inverter (31) and a switch circuit (30) are provided, the order of pilot signals is changed from f1 to f4 to f3 to f2 to
If the reference pilot signals of frequencies f4 and f2 are interchanged, such as f engineering →, the frequency component Δf^ of the difference obtained from the band pass filter (25) will always show a right shift (in the advancing direction), Since the frequency component ΔfB of the difference obtained from the bandpass filter (26) always shows a left shift (lag direction), the inverter (3
1) and the switch circuit (30) are not necessary (see Japanese Patent Laid-Open No. 59-65962).

On the other hand, there is also known a method of performing tracking control using a pilot signal of one frequency without using such pilot signals of four different frequencies.

That is, FIG. 9 is a diagram showing the recording track pattern, and TA, TBi to T B 3 are tracks on which video signals are recorded, respectively, but in this case, the recording trace TH of the horizontal synchronization signal is as shown in the figure. are recorded in a line in the width direction of the track.

The frequency of the pilot signal for tracking control is, for example, 8fH (fH is the horizontal synchronization frequency),
This pilot signal is inserted into horizontal blanking intervals every two horizontal intervals and recorded as shown in FIG. Furthermore, two tracks TA and TB with different azimuths are set as one bear, and the recording traces of pilot signals are shifted by IH (H is a horizontal synchronization interval) for each I pair. Furthermore, the phase of the pilot signal inserted into each horizontal blanking section is as shown in the figure, track TA1. TA2.

T A ]... are all set to O phase, but tracks TB1. In TB2, TB3, etc., the O phase and its opposite phase are recorded alternately.

Then, during reproduction, if this pilot frequency component extracted from the rotary head output is supplied to a comb filter using a 2H delay circuit (41) shown in FIG. 10, an addition circuit (42) and a subtraction circuit ( 43), the reproduction pilot signal output from the raw track to be scanned by the rotary head at that time and the reproduction pilot signal output from the tracks on both sides of the main track are obtained separately.

For example, if the rotating head is on one azimuth track TAI
, TA2, . . ., for example, when scanning track TA 2, the adder circuit (42) scans only track TA 2 at a predetermined level every 2H as shown in FIG. 11A. On the other hand, as shown in FIG.
Regenerated biloft outputs from B1 and T B 2 are obtained alternately for each IH. Also, when the rotating head scans the other azimuth track TB, TB2...
Conversely, the adding circuit (42) obtains the reproduced pilot outputs from the tracks on both the left and right sides of the main track as shown in FIG. 11B, and the subtracting circuit (43) obtains the reproduced pilot outputs from the main track. Obtained as shown in the figure.

Then, the addition circuit (42) or the subtraction circuit (4
3) If tracking control is performed so that the levels of reproduced pilot outputs from both adjacent tracks obtained for each IH are equal, the rotating head will scan across both adjacent tracks by the same amount with the main track as the center. It becomes a state of just tracking.

D. Problems to be Solved by the Invention In the case of the former tracking control method shown in FIGS. 6 to 8, there is a drawback that pilot signals of four different frequencies are required. On the other hand, in the case of the latter tracking control method shown in FIGS. 9 to 11, the pilot signal has the advantage of only needing one type of frequency, but it requires time management in horizontal period units. Further, it has the disadvantage that signal processing is complicated, and since tracking information can only be obtained discretely, there are various limitations when considering compatibility and variable speed playback.

On the other hand, in the case of the former method that uses four-frequency pilot signals, the four types of pilot signals are sequentially switched for each track, so time management is performed on a field-by-field basis (m5ec
However, in the case of the former method, during playback, it is necessary to switch the reference pilot signal to be multiplied by the reproduced pilot signal according to the tape track pattern, so a switch circuit ( 24) and a switch control circuit (20) are required.

E Means for Solving the Problems In the present invention, in an apparatus for recording and reproducing information signals by sequentially forming one track per unit time using the rotary heads HA and HB, the rotary heads HA and HB
The scanning section per track is divided into two, and in the first half, a pilot signal with a first frequency f and a pilot signal with a second frequency rb are alternately recorded every l track, and in the second half, a pilot signal with a first frequency f and a pilot signal with a second frequency rb are recorded alternately. In the section, a pilot signal of the first frequency fa and a pilot signal of the second frequency rb are alternately recorded on every other remaining track, and during playback, the rotating healds HA and HB are scanned once. Tracking control is performed using the pilot signal of the first frequency fa and the pilot signal of the second frequency fb obtained from the reproduced output in the first half or the second half of the interval.

F When a pilot signal is recorded in the first half of the main track that is to be scanned by the rotary heads HA and HB, the first and second frequencies f and fb obtained from the adjacent tracks in the second half of the track are The pilot signal output level is controlled to be equal, and when a pilot signal is recorded in the second half of the main track, the pilots of the first and second frequencies fa and rb obtained from the adjacent tracks on both sides are used in the first half of the main track. The scanning position of the rotary head relative to the tape is controlled so that the signal output levels are equal.

G. Embodiment FIG. 1 shows an example of a tracking control device according to the present invention, and FIG. 2 shows its recording track pattern.

In this example, two rotating heads HA and HB, which are arranged at an angular interval of 180 degrees and have different azimuth angles, are used to wrap a tape obliquely over a 180 degree angle range of the rotating surfaces of these rotating heads HA and HB. On the other hand, this is an example in which a video signal is recorded and played back.

G1 Explanation of recording pilot signal for tracking 3rd
The figure is a time chart during recording, with two rotating heads HA.
and HB are switched by the switching signal RFSW (Fig. 3A). During the period PA when the signal RFS- is "1", the head HA scans the tape, and the signal RFS-
During the period PB when is "0", drum phase servo is applied so that the head HB scans the tape.

In FIG. 1, (51) is a pilot signal generation circuit from which pilot signals of frequencies fa and rb are obtained during recording, and gate circuits (52) and (5
3). In this example fa = 6.5fH, f
b = 7.5fH Ni selection saler.

Further, (54) is a timing signal generation circuit, from which every other cycle of the signal RFS- becomes rlJ in the first half of its "1" period and the second half of its rOJ period,
Moreover, the gate signals G1 and G2 (FIG. 3B and C) whose periods of rlJ are shifted from each other by one period of the signal RFS- are obtained.

Then, the gate signal G1 is supplied to the gate circuit (52), and the gate signal C2 is supplied to the gate circuit (53), and the gate circuit (52) and (53) is in an open state.

Therefore, the period PA during which the head HA scans the tape
In the first half of the period, the signal with the frequency ra and the signal with the frequency rb are alternately supplied to the adder circuit (55) through the gate circuits (52) and (53), respectively, and similarly in the second half of the period when the head HB scans the tape. During the period, the frequency f
The a signal and the rb signal are each connected to a gate circuit (52).
(53) are alternately supplied to the adder circuit (55). The output signal of this adder circuit (55) is
6) and is added to the video signal SV from the terminal (57), and the added signal is supplied to the switch circuit (58). This switch circuit (58) is connected to a terminal (60
) is switched as described above by the head switching signal RFS- from the video signal, and the adder circuit ( 56) is provided.

Therefore, as shown in FIG. 2, video signals are recorded on the tape by heads HA and HB alternately forming tracks TA and TB for each field, as well as the first half of track TA and track TB. In the latter half of TB, the frequency fa is shown with diagonal lines in the figure.
The biloft signal of 1 and the pilot signal of frequency rb are alternately superimposed on the video signal and recorded in a frequency multiplexed manner.

In this case, the left-right relationship of the frequencies of the pilot signals recorded on the tracks on both sides of the track TA and the left-right relationship of the frequencies of the pilot signals recorded on the tracks on both sides of the track TB are recorded so as to be reversed. .

In the above example, approximately 1 of each video track TA and TB
I tried to record the pilot signal in the /2 section, but
Of course, the first half section and the second half section in which the pilot signal is recorded on the track need not be equally divided.

In addition, a rotary head device that can wrap the tape around the guide drum an additional 30° than the 180° angular range and record a PCM audio signal on that 30°, such as in the case of 8mm video. In this case, during the tape scanning period of one head, the biloft signal is applied alone or the PC
The pilot signal may be recorded overlappingly with the M signal, and during the tape scanning period of the other head, the pilot signal may be recorded alone or overlappingly with the video signal in a 180° portion of the video signal track.

Description of tracking control during G2 playback During playback, heads HA and HB are switched by a switch circuit (not shown) in accordance with the switching signal RFSW (Fig. 4A), and this signal RFS- is
During the period PA of ``1'', the head HA scans the tape;
0'' period PB, drum phase servo is applied so that the head HB scans the tape.

The playback output from the heads HA and HB is supplied to the low buzz filter (62) through the terminal (61), and the frequency f
Only the reproduced outputs of the a and rb pilot signals are obtained from this, and these reproduced pilot signals are supplied to the multiplication circuit (63). On the other hand, the pilot signal generation circuit (51) generates a reference pilot signal with a frequency f c =5.
A signal of 5fH is supplied to this multiplication circuit (63). f
Since a=6.5fu and fh=7°5fn, this multiplier circuit (63) calculates the frequency difference Δfa−fH for the regenerated pilot signal of frequency fa as the frequency “
The frequency difference Δfb=2' for the regenerated pilot signal of b
fH is obtained as an output signal.

The output signal of this multiplication circuit (63) is supplied to band pass filters (64) and (65), from the band pass filter (64) a frequency difference ro is obtained, and from the band pass filter (65) a frequency difference 2fH is obtained. are obtained and detected by the detection circuits (66) and (67), respectively. Then, the detection outputs DA and DB of the detection circuits (66) and (67) are supplied to a subtraction circuit (68), and a signal having a level corresponding to the tracking deviation is obtained as the subtraction output. However, as mentioned above in the explanation during recording, the output of this subtraction circuit (68) is based on the left-right relationship between the frequencies of the pilot signals of the adjacent tracks between the track TA scanned by the head HA and the track TB scanned by the head HB. Since these are reversed, the direction of the shift that is meant by the frequency difference is different between the head HA and the head HB. Therefore, the direction of the deviation is corrected by an inverter (69) and a switch circuit (70) switched by the signal RFSW.

Note that if the frequency relationship of the pilot signals of the left and right tracks is the same for tracks TA and TB, the direction of deviation will be the same for heads HA and HB, and the inverter (69) and switch circuit (70) are not necessary. However, there is generally a gain difference between the bandpass filters (64) and (65), and the pilot signal frequencies are f and fb.
However, depending on this difference, there is a difference in the strength of the magnetic field that spreads in the lateral direction, so if the direction of deviation is made the same, the just tracking position of the heads HA and HB will be at the center of the gap width. This results in a state where the track is shifted in one direction from the center in the width direction of the track, that is, a state where the track is shifted from the center track.

In this respect, if the direction of the deviation is reversed, the deviation will not occur, and even if there is a gain difference between the bandpass filters (64) and (65), the difference in the frequency of the pilot signal will cause the magnetic field to change. Even if there is a difference in spread, it will be canceled out and the just tracking position will settle on the center track.

By the way, as is clear from the recording track pattern in FIG. 2, the head HA can obtain the tracking error signal from the pilot signal reproduction output from the adjacent tracks only in the second half of one track scan. ,
Head HB is in the first half. Therefore, the switch circuit (70
) output is the switch circuit (71) and capacitor (72)
The signal is supplied to a sampling and hold circuit consisting of. Then, from the timing signal generation circuit (54), the head H
The second half of the scanning period PA of A and the scanning period PB of head HB
The signal SPI (Fig. 4B) which becomes "1" in the first half of the period is supplied to the switch circuit (71) and is turned on during the period in which it becomes "1".
After the output of 70) is supplied to the capacitor (72) and charged, and the switch circuit (71) is turned off,
The charging voltage at that time is held in the capacitor (72).

In this way, the capacitor (72) has heads HA and HB.
The tracking error voltage is stored in memory, and is supplied to the capstan motor (74) through an amplifier (73), and phase control is applied so that the heads HA and HB are in a just tracking state.

Explanation of the increase in G3 phase lock points Now, let us consider the tracking error information obtained in the latter half of the scan when the head HA moves to the positions shown in (1) to (2) in FIG. 2.

At this time, if the track deviation is plotted on the horizontal axis and the signal output level is plotted on the vertical axis, the detection output DA (second half) of the output of the bandpass filter (64) becomes as shown in FIG. 5A, and the bandpass Detection output DB of output of filter (65)
The (second half) is as shown in Figure B. Therefore, the output DE (second half) of the subtraction circuit (68) becomes as shown in FIG. This relationship in which four tracks have one phase lock point is the same in the case of the four-frequency pilot signal recording system shown in FIGS. 7 to 9.

In the case of the tracking control method that uses a control signal recorded by a fixed head on the edge of the tape in the width direction, which is commonly used in conventional home VTRs, there is one phase lock point for every two tracks, so the above In the case of the above example, theoretically it would take twice as long as the conventional method to lock the tracking servo.

Therefore, in this example, consideration is given to doubling the phase lock point as follows.

In other words, in order to double the phase lock point, the second tracking position of the head HA from ■ to ■ must be adjusted so that the oscillation point of the tracking error voltage in FIG. 5C also becomes the phase lock point. The error voltage DE (second half) may be inverted as shown by the dashed line in FIG. 5C.

On the other hand, considering the reproduced pilot output obtained in the first half of the scan when the head HA moves to the positions shown in Fig. 2, the detection output DA of the output of the bandpass filter (64) The (first half) is as shown in Figure 5, and the detection output DB (first half) of the output of the bandpass filter (65) is as shown in Figure E. Therefore, the subtraction circuit ( 68) output DE
The first half of C) is as shown in F of the same figure. Therefore, at the tracking position including the above-mentioned oscillation point of the tracking error voltage DE (first half) shown in FIG. 5C, the output DE(
(first half) is a positive voltage. Therefore, when this output DE (first half) becomes a positive voltage, the polarity of the tracking error voltage DE (second half) from the subtraction circuit (68) is inverted to bring the oscillation point position of the voltage DE (second half) to the phase lock point. can do.

The above relationship is exactly the same for head HB, except that it is reversed between the first half and the second half of the scan.

To achieve the above, this example uses a switch circuit (
The output of the switch circuit (81) and the capacitor (8
2) is supplied to a sampling and hold circuit consisting of. Then, the timing signal generating circuit (54) generates a signal SP2 which becomes "1" in the first half of the scanning period PA of the head HA and the second half of the scanning period PB of the head) fB (FIG. 4C).
is supplied to the switch circuit (81), and this
”, and during that on period, the output of the switch circuit (70) is supplied to the capacitor (82) to charge it, and after the switch circuit (81) is turned off, the charging at that time is continued. The voltage is held on the capacitor (82). In this way, the capacitor (82) has the head H
In the first half of the scanning period of A, the fifth
A voltage DB (first half) as shown in Figure F is obtained.

The hold voltage of this capacitor (82) is determined by the comparator circuit (82).
3) is supplied to the reference voltage VR1, which is compared with VR=0, and a signal SW (Fig. 5 G) is obtained which is "1" when the hold voltage is positive and rOJ when it is negative. , whereby the switch circuit (84) is switched.

When the tracking deviation is small and the signal SW is "0", the switch circuit (84) is switched to the state shown in the figure, and the signal RPSW from the terminal (60) is supplied as is to the switch circuit (70). On the other hand, when the tracking deviation becomes large and becomes 2 track pitches or more, the signal SW becomes "1", so the switch circuit (84) is switched to the state opposite to that shown in the figure, and the signal RFS- is transferred to the inverter (
85) and supplied to the switch circuit (70), the polarity of the trunking error voltage stored in the capacitor (72) is inverted.

Note that the fourth diagram and E are the outputs of the band pass filters (64) and (65) when the heads HA and HB are slightly shifted to the left from the just tracking position,
F in the same figure is the tracking error voltage held in the capacitor (72) at that time, and C in the same figure is the hold voltage of the capacitor (72) at that time5, and these are the values at position EP in FIG. corresponds to

In the above example, in the tracking control during playback, the frequency difference between the frequency fc signal and the playback pilot signal is obtained using the reference biloft signal, but the biloft signals at frequencies ra and fb are used as a reference biloft signal to obtain the frequency difference with the playback pilot signal. Each of them may be extracted directly and made into a wave.

However, bandpass filters lower the passing frequency and
It is easier to configure the configuration if it is made smaller, and the variation in the passing center frequency is also larger when the frequency is higher, so it is better to lower the reproduced pilot signal by frequency conversion through the multiplication circuit (63) as shown in the example in the figure. good.

Effects of the Invention According to the present invention, it is only necessary to record two types of biloft signals, and at the time of reproduction, there is only one reference biloft signal, and no switch control circuit is required. Or no reference pilot signal is required. therefore,
The configuration is simpler than the system using a four-frequency pyroft signal.

Moreover, since the processing for recording and reproducing the pyro signal can be performed in units of 1/2 field, time management is easier and the configuration can be simplified compared to the systems shown in FIGS. 9 to 11.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an example of a tracking control device according to the present invention, FIG. 2 is a recording track pattern diagram thereof, FIG. 3 is a timing chart during recording, and FIG. 4 is a timing chart of tracking control during playback. Figure 5 is a diagram for explaining the relationship between tracking slippage and phase lock point, Figure 6 is a recording track pattern diagram of an example of a conventional tracking control device, Figure 7 is a system diagram of an example thereof, and Figure 8 is a diagram for explaining the relationship between tracking slippage and phase lock point. 9 is a recording track pattern diagram of another example of a conventional tracking control device, FIG. 10 is a block diagram of an example of its main part, and FIG. 11 is a timing chart for explaining the same.
The figure is a diagram for explaining the same. (51) is a pilot signal generation circuit, (52) and (5
3) is a switch circuit, and HA and HB are rotating heads. Figure 3 Figure 1 P ``wFHA @Tota!Lr: s base 3!L masu Figure 5
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Claims (1)

[Claims] A device for recording and reproducing information signals by sequentially forming tracks of unit length on a recording medium using a rotary head, wherein the scanning section per track of the rotary head is divided into two, and In the first half, every other track has the first
The pilot signal of the second frequency and the pilot signal of the second frequency are recorded alternately, and the remaining one
A pilot signal of the first frequency and a pilot signal of the second frequency are alternately recorded on every other track, and during playback, the pilot signal of the first frequency and the pilot signal of the second frequency are recorded alternately. A tracking control device that performs control so that when a pilot signal of one frequency and a pilot signal of a second frequency are obtained in adjacent tracks on both sides, the output levels of both pilot signals become equal.