JPS6083480A - magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain a noiseless reproduced picture in double-speed reproduction by performing frequency conversion with the reproducing signal of a tape on which pilot signals of four frequencies are recorded and a local signal of one of those frequencies, and driving the tape with the level difference signal. CONSTITUTION:Pilot signals of frequencies f1, f2, f3, and f4 are recorded on slanting unit tracks on the magnetic tape 1 in specific order. A local signal F from a local signal generating circuit 9 having one of frequencies f1-f4 and reproducing signals PL from plural magnetic heads are mixed 30 during double- speed reproduction to select components f1-f2 f3-f4 fH and f1-f4 f2-f3 3fH through BPFs 31 and 32, and signals H1 and H3 obtained by detecting 33 and 34 the envelopes of those signals are inputted to a differential amplifying circuit 35. The circuit 35 generates a (fh-3fh) signal T and a (3fh-fH) signal -T of level differences of both signals, which are extracted and connected alternately by gates 36 and 37 to output a continuous correct tracking error signal TR. The signal TR drives the magnetic heads so that recording tracks are scanned correctly.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic mackerel production device using a magnetic tape.
In particular, by using the bicut signal recorded with a rotating head,
The present invention relates to a magnetic recording/reproducing device configured to obtain noiseless reproduction during double-speed reproduction.

[Background of the invention]

By two rotating heads with different azimuth angles,
In a magnetic recording and reproducing device using the so-called rotating head skewer helical scan-azimuth recording method, which records video signals, audio signals, etc. by alternately scanning diagonally across a magnetic tape, it is possible to quickly locate the tape portion where a desired scene is recorded. A mechanism that plays back magnetic tape by running it at a faster speed than when it was recorded, for example, twice the speed at which it was recorded, in order to skip over unnecessary scenes or to shorten the listening time of audio signals. is used. FIG. 1 shows a track pattern of a magnetic tape recorded using this azimuth recording method. When the magnetic tape (hereinafter referred to as tape) 1 shown in FIG. 1 is played back by running at double speed, the tape 10
Since the running speed is different from that during recording, the rotary heads 5 and 6 scan the tape 1 at an inclination different from that of the recording tracks A and B. For this reason, for example, the first rotary head 5 scans the first track A recorded at the same azimuth angle, and at the same time scans the second track A recorded at a different azimuth angle.
Then, ・riB will also be scanned. In this case, the signal recorded on the second track B is not reproduced due to the azimuth effect.

As the head 5.6 rotates, the low azimuth angle 1. The rate at which the ri is scanned increases or decreases, and the envelope of the generated signal increases accordingly, as shown by the solid line in FIG.

During the period circled in Figure 2 when this ratio decreases, the reproduction level of the signal decreases, so in the case of video signals, horizontal stripes (with poor DS/N) appear on the screen. In the case of audio signals, the dropout compensation circuit operates frequently, resulting in harsh noise.However, in the case of video signals, this noise band is A method has been devised in which noise is not generated on the screen played back on a television receiver by forcing the screen into the blanking period.The tape pattern when played back at 1/12 times speed without generating noise on the playback screen. FIG. 1 shows the scanning trajectories of the heads 5 and 6.

In FIG. 1, in order to perform noiseless double-speed reproduction, it is necessary to control the running phase of the tape 10 so that the heads 5 and 6 draw fidgety scanning trajectories α and A. In order to control this tape running, a control signal CTL recorded on the control track 8 at the lower end of the tape 1 in association with the recording positions of tracks A and B is reproduced by the control head 10 and used. It has been known. This control signal is a tracking control signal recorded by a fixed control head 10 at equal intervals in the longitudinal direction of the tape 1 at a frequency of 1/2 of the vertical synchronization signal of the recorded video signal. becomes a pulse. The positions of tracks A and B can be accurately determined from this reproduction control signal. Therefore, a method was devised in which the phase of the tape 10 is controlled by a signal obtained by delaying this playback control signal using a delay circuit, and by adjusting this delay time, the position of the noise band during double-speed playback is forced into the vertical blanking period. It's been done.

However, in the dragging control method using this control signal, the rotation is 1. Since the position of the fixed control head 1o is far apart from the position of the fixed control head 1o, the tracking will be sluggish due to fluctuations in tape length, etc., so the user needs to perform tracking training by looking at the playback guide. This caused a tracking adjustment mechanism to be necessary.

Another drawback is that tracking errors can only be detected intermittently.
If the pitch of B becomes narrow, sufficient tracking control performance cannot be obtained.

Therefore, tracking errors can always be detected,
An automatic tiger/king control system that eliminates the need for a tracking adjustment mechanism has been devised.

A typical example is a method in which a pilot signal serving as tracking information during playback is superimposed on a video signal and recorded on a video track of a tape using a rotating head. By reproducing this pilot signal to form a tracking error signal and controlling the tape running phase, tracking control can be automated and its control performance can be improved.

However, on the other hand, unlike the above-mentioned control signal-based method, this pilot signal-based tracking control method uses pulses such as control signals recorded in a predetermined positional relationship with the video track in the running direction of the tape, that is, in its longitudinal direction. Video tiger 1. There is no signal indicating the location. Therefore, the conventional noiseless reproduction method using a control signal cannot be applied during double-speed reproduction, and it is necessary to devise a new method.

In addition, if the audio signal recorded by the two rotary heads 5.6 is played back by running the tape at double speed over the entire period in which each of the two rotary heads 5.6 rotates 180 degrees, as shown in FIG. In the area surrounded by a circle where the envelope of the reproduced signal shown by the solid line becomes small, the mud and sop-out compensation circuit operates frequently, as mentioned earlier, resulting in harsh noise. In the case of such an audio signal, unlike the case of a video signal, even if the noise band is forced into the vertical blanking period to obtain a noiseless playback image, the sound signal in the overscan part outside the playback screen is The reproduction level is very low as shown in the period circled in FIG. 2, and the harsh noise does not disappear. As a countermeasure to this problem, for example, by making the gap width of the rotating head used during reproduction wider than the pitch of the recording track, or by changing the relative height of the two heads, it is possible to achieve the effect shown by the broken line in Figure 2. Since the envelope reproduction signal can be obtained, some improvement is possible. However, high accuracy in controlling the tape running phase is still required.

Therefore, drastic measures were required to expand the control margin and, in particular, to increase the reproduction level of audio signals.

[Purpose of the invention]

In view of the above points, an object of the present invention is to provide a means for obtaining a noiseless reproduced image or noiseless reproduced sound during double speed reproduction in a magnetic recording and reproducing apparatus of the type that performs tracking control using a pilot signal recorded with a rotary head. It is about providing.

[Summary of the invention]

In order to achieve the above object, the present invention provides 48+ @ pilot signals of frequencies f1 to f4 for each track.
When recording on a tape in the order of 4 and playing back at double speed, a local signal having one type of frequency among the four frequencies is generated, and using this local signal of one frequency,
The frequency of the regenerated pilot signal is converted to a lower frequency band, and the converted wave number component signal and Jflfal−1ft f++l
#5 Select a signal with a frequency component of fH, and Chl-, which is the level difference between the fH acid component signal and t, the fH acid component signal.
3fH) signal and (5fu-fH) signal, and the (fH-3fn) signal and (3fH-fu
) signal is alternately switched and output, and the tape running phase is controlled according to this output signal, so that the rotating head correctly scans the desired recording track on the tape.Tracking control during double-speed playback have them do it.

At this time, for example, the video signal or the audio signal may be reproduced from every other track recorded at the same azimuth angle using two heads with the same azimuth angle and arranged at an angle of about 180 degrees from each other. Configure.

[Embodiments of the invention]

The present invention will be explained in detail below using the drawings.

First, tracking during standard playback using pilot signals.
The control method will be explained with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing an example of a track pattern on the tape 1 in which a pilot signal is recorded by superimposing it on a video signal. 1. FIG. 4 is a block diagram showing a circuit 22 and the like for forming a tracking error signal TR from a reproduced pilot signal PL.

In Figure 6, AI and A2 are +azimuth angle CH1
This is the track recorded on head 5, and is B.

and B2 are tracks recorded by the CH2 head 6 at a -azimuth angle. Further, fl-fa indicates the frequency of the pilot signal recorded on each track. In this way, four-frequency pilot signals are alternately recorded for each track. The frequency fl-fa of each pilot signal is selected to be a frequency that is lower than the frequency band of the video signal and is not affected by the azimuth angle of the head 5.6. Therefore, when the heads 5 and 6 scan the recording track during standard playback, it is possible to detect not only the biro and vto signals of the track being correctly scanned, but also the pilot signals of the adjacent tracks on both sides. . Therefore, by detecting the reproduction levels of the pilot signals of both adjacent tracks and calculating the level difference, it is possible to obtain an accurate tracking error signal that includes the direction of the tracking deviation and its character.

Now, the frequencies of the four-frequency pilot signals shown in Fig. 6 are f1=6s fH+ f2= 75 fH+ fs=
1o, s fu +h=95fHc where fH is the frequency of the horizontal synchronizing signal of the video signal), then track AI
+ When scanning A2, if the tracking shifts to the right, 1ft-f21=1fs fa1=fII component increases, and conversely, if it shifts to the left, 1f□-f41. = lf
s f21=3fH component increases. 1. Track B1.
When scanning B2, if the tracking shifts to the right 11, the 1f2fs1-1f4fl=5fH component increases, and conversely, if the tracking shifts to the left, 1fz f11=1f4f, 5l-f
Increases H acid content.

Therefore, in FIG. 4, the switch 43 is switched to the PB terminal side, and the local signal generation circuit 9 generates a local signal F having the same frequency as the pyrolide signal recorded on the main track to be scanned. and,
The reproduced pilot signal PL is sent to a mixer circuit 30 consisting of, for example, a double-balanced modulator, and a signal having the difference frequency between the two signals, that is, a composite signal of the fH acid component and the 5fH component, is obtained at its output. Next, bandpass filters 31 and 32 filter fH from this composite signal.
The +3fH component is separated, and the envelope detection circuits 33 and 34 generate detection voltages H1 and H3 with values corresponding to their respective amplitudes.The differential amplifier 35 calculates the difference between the two. A difference signal T, 〒 is obtained as a dynamic output. The difference signals T, T represent the level difference between pilot signals detected from adjacent tracks on both sides of the main track to be scanned.

At this time, when the main track is A or A2, and when the main track is Bl
Or in the case of B2, the difference frequency component H in the direction of tracking deviation as described above.

5f) The direction of increase/decrease in l is reversed. Therefore, the differential amplifier 3
5 to two difference signals with different polarities, T=ACH1-H
s), T=A(Hs us), (': constant), and the differential outputs T and T are supplied to gate circuits 36 and 37, respectively. and. Head phase detection signal S with one frame period that detects the rotational phase of the head 5.6
W is used as the gate signal G, and this signal SW and a signal whose polarity is reversed by the inverter circuit 40 are sent to the gate circuit 3.
6 and 37, close the gate of the gate circuit 36 during the period when the gate signal G is at high level, close the gate of the gate circuit 37 during the period when the gate signal G is at low level, and output the signals T, T for each field. A continuous correct tracking error signal T is obtained by connecting the difference signal T, which has a different polarity for each scan of one track, by alternately transmitting the
Get R.

In this way, the tracking error detection circuit 22 of FIG. 4 can form the tracking error signal TR from the reproduced pilot signal PL during standard reproduction. In FIG. 4, the local signal generation circuit 9 includes a four-frequency pyro, soto signal generation circuit 11, and a rotation control circuit 1.
2, a 4-frequency local signal during standard playback, and 2
Forms a single frequency local signal during double speed playback.

Next, FIG. 5 is a block diagram showing an embodiment of a rotational/helical scan type magnetic recording/reproducing apparatus according to the present invention. FIG. 6 also shows three heads 5, which are attached to the rotating cylinder 4 of the magnetic recording/reproducing apparatus shown in FIG.
FIG. 6 is a diagram showing the positional relationship between 6 and 5'.

In the magnetic recording/reproducing apparatus shown in FIG. 5, three heads are used: a CH1 head 5 and a CH3 head 5' having exactly the same +azimuth angle, and a CH2 head 6 having a -azimuth angle. These heads are connected to a rotating cylinder 4 as shown in FIG.
The CH1 head 5 and CH2 head 6 are installed with exactly 180 degrees of displacement, and the CH3 head 5' is attached to the CH
It is installed at a position close to the CH2 head 6, that is, at a position approximately 180 degrees away from the CH1 head. During recording and standard playback, CI (1 head 5 and CH2 head 6) having different azimuth angles are used. On the other hand, during double speed playback, CH1 head 5 and CH3 head 5' having the same azimuth angle are used.

FIG. 5 shows a block diagram at the time of reproduction, and using this diagram, first, the operation at the time of recording the video signal will be briefly described. During recording, the tape 1 is driven by the capstan 2 and runs in the direction of the solid arrow. This capstan 2 is rotationally driven by a capstan motor 3. On the other hand, the CH1 head 5 is attached to the rotary cylinder 4 at a distance of 180 degrees from each other. The CH2 head 6 is driven by a cylinder motor 7 and rotates in the direction of the dashed arrow. This cylinder 4 is attached to a rotating shaft inclined with respect to the longitudinal direction of the tape 1, and has a frequency of 1/2 of the vertical synchronizing signal of the recorded video signal (i.e., frame frequency).
Rotationally driven. Further, the tape 1 is wound around the cylinder 4 over approximately a little over half a circumference. therefore,
The heads 5 and 6 alternately scan the tape 1 in diagonal directions from bottom to top, and record the video signal and the tracking pilot signal in units of one field of the video signal.

Next, the operation when playing back at standard speed will be explained. In FIG. 5, during standard playback, the switch 43 is switched to the PB terminal side. During standard playback, CH1 head 5.
The rotational phase of the CH2 head 6 is detected by the tack head 16, and this detection signal is sent to the phase adjustment circuit 14, which outputs the head phase detection signal sw and the reference signal generation circuit 15.
The phase comparator 16 compares the phase with the reference signal REF generated by the head 5.
6 is rotated at a constant phase and speed determined by the reference signal REF. If the frequency of this reference signal REF is selected to be approximately equal to the frame frequency, then 5. The rotational speed of B becomes almost the same as at the time of recording.

In this way, when the heads 5 and 6 are rotated at a predetermined speed, π
1. By controlling the running of the tape 10 using the tracking error signal TR described above, tracking control is performed so that the head 5.6 accurately scans a desired recording track.

Next, the tiger and king control operations during standard playback will be explained.

First, the rotational speed of the capstan 2 is detected by the speed detector 26, and this detection signal is sent to the frequency discriminator 24 to convert it into a speed control voltage SP according to the rotational speed. By supplying power to the capstan motor 3 through the 26° motor drive circuit 18, speed control is performed so that the capstan 2 rotates at a predetermined speed. Note that 25 is a rotation speed setting circuit for the capstan motor 3.

On the other hand, the signals reproduced from the tape 1 by the heads 5 and 6 are sent to the preamplifier 19 via the rotor IJ lance 28 and amplified. This amplified reproduction signal R
F is further sent to the video signal reproduction circuit 20 and also sent to the tracking error detection circuit 22 via the low-pass filter 21. By the low-pass filter 21,
The commercial area video signal is removed from the reproduced signal RF, and only the pilot signal PL is separated and extracted. From this pilot signal PL, the tracking error detection circuit 22 forms a tracking error signal TR using the method explained in FIG. A signal TE obtained by smoothing this tracking error signal TR by an integrating circuit 27 is sent to an adder 21 to generate a speed control voltage S.
The rotation of the capstan 20 is controlled by adding it to P and supplying it to the capstan motor 6 via the motor drive circuit 18. As a result, the running phase of the tape 10 is controlled in accordance with the tracking error signal TR during standard playback, and tracking control is performed so that the heads 5 and 6 correctly scan the recording tracks.

Next, a description will be given of means for detecting a pilot signal recorded on a video track during double-speed playback to realize noiseless playback. First, in FIG. 5, the rotation speed of the capstan motor 30 is set by the speed setting circuit 25 so that the running speed of the tape 1 is approximately twice the speed during recording.

Furthermore, in FIGS. 4 and 5, the switch 43 is
Switched to the terminal side, as will be described later, unlike the signal in which four frequencies 11 to f4 are rotated during standard playback as the o-cal signal F, during double-speed playback, only one frequency, for example, a signal with a frequency fl is used. . Also, gate signal G
The same head phase detection signal SW used during standard reproduction is used as the head phase detection signal SW.

Also, when playing at double speed, approximately 180
1. To CHl of the same azimuth angle arranged in a different manner. Do 5
and CH3 head 5' are used.

Figure 7 shows the recording track pattern on the tape 1 and the C when the tape 1 is run at twice the speed in the same direction as during recording.
Scanning trajectory co, do of H1 head 5 and CH3 head 5'
This is what is shown. In FIG. 7, At + B+
+ A2 + Bt indicates recording tracks as in Fig. 3, and co and do tracks with steeper slopes than these recording tracks.
shows the scanning locus of the head 5.5' during double speed reproduction.

Further, FIG. 8 is a timing chart showing signal waveforms, etc. during double speed playback operation.

Now, in FIG. 7, if the running phase of the tape 1 is controlled so that the CH1 head 5 draws a scanning trajectory c6 and the CH5 head 5' draws a scanning trajectory a, then the heads 5,
5' scans the roughly vertically hatched portion of the track At+A2 recorded with a head (for example, head 5) having the same +azimuth angle. That is, head 5.5
' respectively scan over the widest range on recording tracks At + Ax of the same azimuth angle, both of which can reproduce signals. At this time, as shown in FIG. 8(2), the reproduced signal by the two heads and ends 5, 5' is changed every time the level of the head phase detection signal SW shown in FIG. 8(1) changes, that is, 1.
It is switched for each field, and an envelope RF' of the reproduced video signal as shown in FIG. 8(5) is obtained. (Head 5
, 5', the gap width TW is equal to the recording track pitch TP.

) This reproduction envelope RF' reaches a minimum near the vertical blanking period, but it only decreases to 1/2 of the maximum value, and no noise band occurs even during this minimum level period. This minimum level in FIG. 8 (3) is compared with the minimum level of the reproduction envelope (solid line in FIG. 2) when heads 5 and 6 scan trajectories α and b as in the conventional example shown in FIG. I become overwhelmingly dog-like. Therefore, the scanning method shown in FIG. 7 is extremely effective for increasing the S/N ratio of the reproduced signal. (By making the head width of Naohe Sodo 5, 51 wider than the track width TP, the minimum level shown in FIG. 8(3) can be further increased.

) In the present invention, the heads 5 and 5' scan co+do in FIG. This is controlled. Therefore, l and the tiger in Figure 4,
In the soaking error detection circuit 22, a mixer circuit 3 is used to convert the frequency of the reproduced pilot signal PL to a low frequency range.
0, switch 43 is connected to Q
The U terminal is switched to 1 μjl, and the local signal F whose frequency is always 11 is used as shown in FIG. 8 (4). i"i!, A
During the field period, the CH1 head 5 selects a track in which 11 pilot signals are recorded, as shown in CQ in FIG.
When scanning is performed centering on RIAl, the rate of scanning on the adjacent track on the left side gradually decreases in the first half of the scan, as clearly indicated by the dots in FIG. Since the f4 pilot signal is regenerated in the part where this one point is applied,
A local signal F having a frequency of f+ is converted to a low frequency by the mixer circuit 3o in FIG. 4, and a 5fH component is obtained.

Therefore, the voltage HJ of the 5fH component selected by the 5fu band hash filter 32 and detected by the envelope detection circuit 34 changes as shown in FIG. 8(5) during the A field period. Further, in the latter half of the scanning period when the CH1 head 5 scans as shown in c6 of FIG. 7, the rate at which the adjacent tracks on the right side are scanned gradually increases, as clearly indicated by fine horizontal hatching in FIG. In this fine horizontal hatched area, the pilot signal of f2 is reproduced, so it is low frequency converted by the mixer circuit 3° by the local signal F of frequency fl, and fI (bandpass filter 3
1, the fH acid component voltage H1 detected by the envelope detection circuit 36 is selected in the 8th field during the A field period.
It changes as shown in figure (b). Therefore, the differential amplifier 35
5fH detection voltage Hs and fH detection voltage H output from
The difference signal T=' (Hs Hs ) changes as shown in FIG. 8 (8) during the A field period.

Next, during the B field period, if the CH3 head 5' force is scanned centering on track A2 where the pilot signal of f3 is recorded as shown in Figure 7, the pilot signal of f2 on the left side is recorded in the first half of the scan. The rate at which the recorded adjacent tracks are scanned gradually decreases, and in the latter half of scanning, the rate at which the pilot signal 14 on the right side is scanned at the recorded adjacent tracks gradually increases. Since the frequency of the local signal F at this time is fl as shown in FIG. 8 (4), '5f1 of the low-frequency converted reproduced pilot signal
The detected voltage Hs of one component and the detected voltage H1 of fH component are the eighth
As seen in Figures (5) and (S), Hs changes in the opposite way to )11 during the A field period. That is,
Hs in the B-field period exhibits the same change as Hl in the A-field period, and Hl in the B-field period exhibits the same change as 3 in the A-field period. Therefore, B
'5 output from the differential amplifier 35 during the field period.
Difference signal T between fH detection voltage H3 and fI (detection voltage H1)
-A (Hs I(+) has the opposite polarity to T in the A field period, and during the B field period, the other difference signal T = ', (Ht
Hs ) changes exactly the same as T in the A field period.

Now, in the embodiments shown in FIGS. 7 and 8, when the tape 10 running phase is delayed and the head 5 scans to the left from the trajectory co that should be scanned, the 5fH component H3 increases and the fH acid component 1 decreases, so the difference signal T −'
(Hs Ht) increases. Conversely, if the running phase of the tape 1 advances and the head 5 scans to the right from the trajectory c6 that should be scanned, the '5fH component H3 decreases and f
Since the u acid component 1 increases, the difference signal T decreases. On the other hand, when the head 5' scans all the way to the left from the trajectory do, the fH acid component 1 increases and 3fH
Since the component H3 decreases, the difference signal T ='(Hl-Hs
) goes up. Conversely, if the head 5' scans to the right from the trajectory do that should be scanned, fI (component H1
decreases and the 3fH component H3 increases, so the difference signal T decreases.

In this way, the A field period in which the head 5 scans the tape 1 and the B field period in which the head 5' scans the tape 1 are such that the direction of increase and decrease of the difference signals T and T with respect to the direction of tracking deviation is opposite. Become. Therefore, in FIG. 4, two difference signals T, 〒 with different polarities are output from the differential amplifier 55, just as in the case of standard reproduction, and the differential output T.
, T to the gate circuits 56 and 37, and the head phase detection signal SW (FIG. 8 (1)) is supplied to the gate signal G.
[FIG. 8 (7)] As shown in FIG. 8, during the A field period when the gate signal G is at a low level, the gate circuit 36 is opened, while the gate circuit 67 is closed and the difference signal 〒=A During the B field period when only (H3H1) is passed and the gate signal G is at a high level, the gate circuit 3
7 is opened, while the gate circuit 66 is closed and the difference signal T-
Only A (H knee H3) is allowed to pass. By alternately transmitting the difference signals T and 〒 for each field in this way,
The difference signals T and 〒 having different polarities for each scan of one track are connected to obtain a continuous correct trazokink error signal TR as shown in FIG. 8 (8). This error signal TR is smoothed by an integrating circuit 27 as shown in FIG. By supplying the power to the capstan motor 6 through the drive circuit 18, the 20 rotations of the key 112 are controlled.

For example, if the running phase of tape 1 is delayed, as shown in Fig. 8 (
Feedback control is performed such that the average voltage TE of the tracking error signal TR in step 8) increases, the rotational speed of the capstan motor 6 increases, the running speed of the tape 1 increases, and the running phase advances. As a result, during double speed reproduction, the running phase of the tape 1 is controlled in accordance with the tracking error signal TR, and tracking control is performed so that the head 5.degree. 5' scans C6.dO in FIG.

Next, FIGS. 9 and 10 show changes in the tracking error signals TR and TE with respect to tracking deviations of the rads 5 and 5'. Figures 9 and 10 show the frequency of double-speed playback when the frequency of the local signal F is fixed to fl and the head phase detection signal SW is used as the gate signal G, as shown in Figure 8. FIG. 3 is a diagram showing the operating principle of tracking control.

In FIG. 9, (1) shows a track pattern in which pilot signals of frequencies af1 to f4 are recorded and a head 5.
．． 5' scanning locus. The hatched area on the side represents the part where the pilot signal is low-frequency converted and becomes the fH acid component, and the dotted area is the pilot signal that is low-frequency converted and becomes the 3fH component. Figure 9 (2) shows the frequency of the local signal F, Figure 9 (3) shows the head phase detection signal SW and gate signal a, and Figure q (4) shows the frequency of the local signal F. 9 shows the tracking error signal TR corresponding to P and its average value TE. In other words, in FIG.
Tracking error signal TR when scanning the toilet opening slightly shifted from l to Pe'J.

TE is shown. At this time + azimuth angle head 5
．． 5' are shifted by two track pitches from each other, and each f
Pilot signals of frequencies l and f3 are recorded. Centering on the track with the same +azimuth angle, c of Ps
In order to control the scanning like o+do, the frequency of the local signal F is fixed to <fl as shown in FIG. 9(2), and the scanning of the heads 5 and 5' is turned off as shown in FIG. 9(6). A gate signal G whose level changes every field is used.

The state of P5 in FIG. 9 is a case where the head 5.5' scans by drawing exactly the same locus eo+do as in FIG. The signal has the same waveform as 8).

Therefore, this error signal T Rs is
The average voltage T Es smoothed by 7 is a voltage at which the difference between the '5fH component and the fH acid component becomes zero. This is Figure 9 Pl
i and as shown in FIG.
The part of the tiger pattern (horizontal) where the component signal is generated.
This is also clear from the fact that the portion of the track pattern where the fH acid component signal is generated (the dotted portion) has the same area.

FIG. 9(1) shows an example where the heads 5, 5' do not scan correctly along the trajectory Ps.

For example, as shown in P4 (1), if scanning is performed such as e4+d4 with half the track pitch shifted to the left from the optimum state of Pll, no point will be reached during the scanning period of C4 when the gate signal G is at a low level. Show it! Only the trunk pattern portion where the 1fH component 0 signal is generated occurs, and during the scanning period of d4 when the gate signal G is at a high level, only the trunk pattern portion where the fn component signal shown by horizontal 7% cutting is generated. .

Therefore, the tracking error signal T R4 is P4(
4), the average voltage TE4 increases. As shown in Pl(1) in FIG. 9, if the head 5.5' is shifted one track pi to the left from the optimum state of Ps and scans as e3+d3, then 5f of C3
The H component and the fH acid component of d3 further increase, resulting in a signal with a waveform as shown in the tracking error signal T Rs#i Ps (4), and its average voltage T Es further increases. P
As shown in 2(1), there is a shift of 1.5 track pitches to the left from the optimal state of Ps, resulting in e2+d! Even in the case of scanning as shown in FIG.
The average voltage TE2 of the tracking error signal TR2 shown in 2(4) also becomes equal to the TEA of R4(4). The tracking error signal TR2 of R2 and the error signal TR4 of R4
and have opposite polarity around the same average voltage. Also, when scanning cl and dl with a two track pitch shift to the left from the optimal state of ps as in P+(1), the area where the 6fI component signal is obtained and the area where the fH acid component signal is obtained. are equal, so P, (4)
The average voltage TEI of the tracking error signal TR1 shown in is also equal to TEs of P, (4). This Pt(1)
The envelope waveform of the video signal reproduced by the heads 5, 5' in the scanning state of Ps(') becomes an ideal waveform as shown in FIG. 8(3), as in the scanning state of Ps('). However, the tracking error signal TR1 of Pl and the error signal TR5 of R5 have a relationship of opposite polarity with respect to their average voltage.
That is, since the direction of tracking deviation and the direction of increase/decrease of the tracking error signal TE are opposite between Pl and Ps, Pl(1) and Ps are in an unstable state unlike R5(1).

Also, in FIG. 9, the head 5.5' is 2 to 1 from the optimum state of Ps as shown in Ps('). If the scanning is performed as shown in C6+d6 by shifting half of the square to the right, during the scanning period of C6 when the gate signal G is at a low level, only the track pattern portion where the fH acid component signal shown by horizontal hatching is generated, d6 when gate signal G becomes high level
During the scanning period, only the track pattern portion where the 5fI (component signal) shown by the dot is generated. Therefore, the tracking error signal TRs decreases as shown in Pg (4), and its average voltage TEs becomes low.Py As shown in (1), when scanning is performed by shifting one track pi to the right from the optimum state of R5 to 07+d7, the fI component of C7 and the 5fI component of d3 further increase, and the tracking error signal TR, changes to R7. A signal with a waveform as shown in (4)9
, its average voltage TEy becomes even lower.

When scanning as c@+dg with a shift of 15 track pitches to the right from the optimum state of Pg as in Ps(1), C8 becomes only the fH acid component signal and d8 becomes only the 3fI component signal, and its area becomes Pa ('), the average voltage T & of the tracking error signal T Rs shown in Ps(4) also becomes equal to TEs of R6(4).

The tracking error signal TRs of R8 and the error signal TR of R6 have a relationship of opposite polarity around the same average voltage. In addition, when scanning as in c@, do with a shift of 2 trs to the right from the optimal state of R5 as in Pl (1), the shift of 2 to the left from the optimal state of P.
The exact same scanning state as Pl (1), which was scanned like C1+ d
) tracking error signal TRs.

TE9 is T Rt and T Et of P+ (4), respectively.
is equal to Note that there is a tracking error in FIG. 9 (4).

The average voltages T El , T Es , and T Is of the difference signals are all equal voltages at which the difference between the 5fI component and the fH acid component becomes zero.

In this way, the average voltage TE of the tracking error signal TR changes depending on the scanning position of . Therefore, this average voltage TE can be used as a signal representing the tracking state of the head. Note that the tiger/7king error signal TR is a signal that represents the tracking state of the head, but in reality, the recording level of the pilot signal is kept low in order to eliminate interference with the video signal, so noise may occur. When undisturbed, the instantaneous values do not necessarily represent the exact scanning position of the rad. Therefore, by smoothing this signal TR, both during standard playback and during double speed playback, a signal TE representing the average scanning position of the front and back is formed, which is used as a substantial tracking control signal. .

Next, FIG. 10 shows the scanning position of the heads 5, 5' (the scanning position at the time when the heads 5, 5' have passed half of the scanning period of one field, that is, the scanning position of the heads 5, 5' shown in FIG. 9 (1)). The horizontal axis represents the center position of the scanning trajectory c+d, and the vertical axis represents the average voltage TE of the tracking error signal.

The scanning position shown in Pl-Pe in FIG. 9(1) and the first
0 corresponds to the positions indicated by P1 to P9 of the same number -M in the figure.

In this way, the tiger 1 shown in FIG. King error detection circuit 2
2, fl is always given as the local signal F during double speed reproduction, and the head phase detection signal S is given as the gate signal G.
When W is applied, the average voltage TE of the tracking error signal TR changes as shown in FIG. 10 depending on the scanning position of the head 5° 5'. Therefore, the average voltage TE of this tracking error signal is calculated by the adder 21 as shown in FIG.
By supplying the signal to the capstan motor 3 via the motor drive circuit 18, the rotational phase of the capstan 2, ie, the running phase of the tape 10, can be controlled to obtain a desired tracking state. At this time, in Fig. 10, when the tracking shifts to the right, the tracking error signal TE becomes downward υ, and when the tracking shifts to the left, TE increases, resulting in negative feedback control, as described in Fig. 9. It is. Therefore, the scanning position of Ps becomes the center of control.

In addition, in FIG. 7, when the head 5' scans da, which is the center of control, it scans mainly on the track A2 where the pilot signal of frequency f3 is recorded, so the reproduction level of the pilot signal of frequency 13 is high. Local signal F
The low frequency is rejected by the frequency 11 of fl (5fH=4
The fH component becomes thicker. However, since the frequency is separated by fH from the center frequency of the 3fH bandpass filter 32, the 4fH component is sufficiently attenuated by the filter 32, and there is no fear that it will interfere with the detection of the 3N component.

In addition, in the above operation explanation, for convenience of explanation, it was assumed that when the head scans an adjacent track, the pilot signal recorded on this adjacent track is detected, but in reality, the head gap is If it is close to a track, it is possible to detect the magnetic flux of the pilot signal recorded on the adjacent track to some extent due to crosstalk even when the track is not being scanned.

Therefore, the portion of the tape pattern where fH oxidation is detected and the portion where 3fH component is detected in FIGS. 7 and 9, and the waveforms of the signals shown in FIGS. 8 and 9 are slightly different from the actual ones. However, depending on the side-leading effect of this head, the operating principle of tracking control and its control performance during double-speed playback do not change as described above.

Furthermore, in the above embodiment, a method was described in which the frequency of the local signal F is always fixed at fl, but in FIG. When the signal is used, the head 5 is controlled to scan aO shown in FIG. 7, and the head 5' is controlled to scan c (1), contrary to the above embodiment. Since they are equal, the envelope RF' of the reproduced video signal is exactly the same as that shown in FIG. 8 (6).

Furthermore, by fixing the frequency of the local signal F to f3 and inverting the polarity of the gate signal G shown in Fig. 8 (7), the tracking error signal exactly the same as Fig. 8 (8) can be obtained. Even in this case, tracking control can be performed so that the heads 5, 5' scan C0do in the same manner as in the above embodiment & in FIG.

In addition, in FIG. 6, a CH4 head 6' (not shown) with a single azimuth angle is installed near the CH1 head 5, and double-speed reproduction is performed using the CH2 head 6 and CH4 head 6' with the same azimuth angle. In this case, by always fixing the frequency of the local signal F to the frequency f2 or f4 and using the head phase detection signal SW1 or a signal SW of the opposite polarity as the gate signal G, one azimuth angle in FIG. Scanning centered on the recording tracks B1 and B2 is obtained, and the envelope RF' of the reproduced video signal is exactly the same as that shown in FIG. 8(3).

In this way, the frequency f of the four-frequency pilot signal is determined according to the azimuth angle of the two heads used for double-speed playback! ~f
4, one type of frequency is selected as the frequency of the signal F.

Further, in the above embodiment, the CH1 head 5 scans the tape 1 when the head phase detection signal SW is at a low level, and the CH3 head 5' scans the tape 1 when the signal SW is at a high level. However, on the contrary, the signal S
The head 5' may scan the tape 1 when the signal W is at a low level, and the radar 5 may scan the tape 1 when the signal SW is at a high level. In this case, from the relationship with the gate signal G, the seventh
In the figure, the head 5 scans aO, and the -rad 5' is c
It is controlled to scan o. - [Effects of the Invention] As described above, the tracking control method during double speed playback according to the present invention uses the level difference between the pilot signals detected from the left and right adjacent tracks of the main track to be scanned, as in standard playback. This method controls the running phase of the tape according to the recording speed, and therefore achieves almost the same height control stability as during standard playback, and also achieves sufficient automatic control performance even during long-term recording. , the tracking is of course tidied up.

In addition, tracking control during double speed playback like this,
Also serves as the circuit used for tracking control during standard playback,
This can be done simply by providing a circuit that switches only the local signal supplied to the tracking error detection circuit from that during standard playback.

Therefore, it can be realized with a simple and inexpensive control circuit.

In addition, in a magnetic recording/reproducing device having a field still function using three heads as shown in FIG. 6, which has been widely used in the past, the double speed reproduction function according to the present invention can be added without installing a new head. . If this field still function and double speed playback function are installed together, two
This has the advantage that the insertion timing of the pseudo vertical synchronizing signal added before the reproduced vertical synchronizing signal can be made common in order to prevent the vertical vibration of the reproduced image that occurs when the interval between the heads is not 180 degrees.

According to the present invention, even when a head having a gap width TW whose minimum level of the reproduced signal envelope obtained during double speed reproduction is equal to the track width TP is used, the eighth
As shown in Figure (3), it is half of the maximum level, which is higher than that of the conventional method. can be dramatically increased. Therefore, not only the output level of the video signal described in the above embodiment is increased to obtain high-quality double-speed playback images, but also the output level of the audio signal recorded by the rotary head is increased, resulting in high-quality double-speed playback. A great effect can be obtained in that the reproduced sound cannot be obtained.

[Brief explanation of the drawing]

Fig. 1 is a tape pattern diagram showing a conventional head scanning trajectory, Fig. 2 is a waveform diagram showing a conventional playback signal envelope,
FIG. 6 is a tape pattern diagram according to the present invention, FIG. 4 is a block diagram showing a specific example of a tracking error detection circuit according to the present invention, and FIG. 5 is a configuration example of a magnetic recording/reproducing apparatus according to the present invention. 6 is a sectional view showing a head configuration according to the present invention, FIG. 7 is a tape pattern diagram showing an example of a head trajectory according to the present invention, and FIG. 8 is a main part signal of an embodiment of the present invention. FIG. 9 is an explanatory diagram showing the head scanning position and essential signals of an embodiment of the present invention, and FIG. 10 is an explanatory diagram showing the tracking error signal according to the present invention. DESCRIPTION OF SYMBOLS 1... Magnetic tape, 6... Gear Bustan motor, 5.5', 6... To rotation, Rad, 9... Local signal generation circuit, 22... Tracking error detection circuit, 27. ...Integrator circuit, 30...Mixer circuit, 36, 37...Gate circuit, 43...Switch. 1st attack 5th Zusu 5th day Otsukuni 7 of 7 fs JiH 80th 躬 9 口〔PI〕 鵠) ' (P3) [1] Sail〕[a] No. ′/Country CFｑ) C ri Kabura]謬／θm

Claims (1)

[Claims] A magnetic tape on which four types of pilot signals having frequencies of 'L flr f2 + flr f4 are recorded in a predetermined order for each inclined unit track, and during reproduction, the magnetic tape is recorded at twice the frequency of recording. a tape drive device configured to run the magnetic tape at a high speed; a plurality of rotary heads for reproducing the pilot signal recorded on the magnetic tape during the double speed playback; a local signal generation circuit that generates a local signal having one type of frequency; a frequency conversion circuit that converts the frequency of the reproduced pilot signal to a lower frequency using the local signal having the one type of frequency; 1f1-fzl average 1fs from the output signal of the frequency conversion circuit? 41L
; A signal with a frequency component of fH, and L+'1fJ#If
2-fsl#3fI (a circuit that selects a signal with a frequency component of
A circuit that forms a signal, and a unit time silver bar (fH-3
A gate circuit that alternately switches and outputs an fH) signal and a (3fH-fH) signal, and an output signal of the gate circuit is supplied to the tape drive device, thereby controlling the plurality of rotating heads during the double speed playback. A magnetic recording/reproducing apparatus comprising: a device for performing tracking control so as to correctly scan a desired recording track on the magnetic tape. 2. The plurality of rotations are approximately 18 degrees apart from each other.
2. A magnetic recording and reproducing apparatus according to claim 1, characterized in that two rotary heads having the same azimuth angle and arranged with zero variation are used.