JPS5948819A - Tracking device - Google Patents

Abstract

PURPOSE:To increase the lifetime of an electric-mechanical transducer, by exercising control to minimize the DC voltage component of a switch timing signal of a reference signal when the driving voltage is applied to said trasducer which gives a displacement to a record track. CONSTITUTION:Magnetic heads 40 and 41 are attached to electric-mechanic transducers 42 and 43 respecrively and revolved by a DC motor 47 together with revolving phase detecting magnets 44 and 45 in one body with a rotary disk 46. A revolving phase detector 48 is set in correspondence with magnets 44 and 45. A magnetic tape 52 is driven by a capstan 53 and a pinch roller 54. The driving voltage is mixed by an MIX circuit 36 between transducers 42 and 43, and the DC voltage component is extracted through an LPF46. A pseudo control signal generating circuit 65 varies the ratio of the output of a capstan FG amplifier 61 in response to the DC voltage component. The output of the circuit 65 is controlled to switch the oscillation frequency of a reference signal generating circuit 66 to minimize the DC voltage component which is applied to the transducers 42 and 43. This prevents the deterioration of sensitivity and therefore increases the lifetime of the transducers 42 and 43 respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tracking device for a helical scan rotary head video tape recorder (hereinafter referred to as VTR).

Conventional configurations and their problems In recent years, in video signal magnetic recording/reproducing devices or video signal magnetic reproducing devices using magnetic tapes such as VTRs, the purpose of accurately π-traversing the IC and distribution tracks ζf1 during playback has been increasing. So-called auto-tracking devices began to be introduced. This auto-tracking device supports slow playback, still playback, and playback at a speed different from the tape running speed during recording.
In special antiquity modes such as fast playback and reverse playback, it is possible to provide a reproduced image without noise bands. Such an auto-tracking device usually attaches a magnetic head for video (M size reproduction) to an electro-mechanical transducer, and converts the magnetic head by applying a drive voltage corresponding to the track displacement to the electro-mechanical transducer. It constitutes a control system that allows accurate on-tracking on the recording track.In this type of tracking device, the information in the reproduction signal is a signal whose frequency differs periodically for each recording track during recording. (hereinafter referred to as a pilot signal) is superimposed and recorded with a video signal, and during playback, the amount of crosstalk of pilot signals in recording tracks that are adjacent before and after the recording track to be reproduced and have different frequencies is detected. The method of creating a tracking error signal using a pilot signal detects the phase shift between the recording track and the magnetic head by comparing the two types of pilot signals.
Various types of pilot signals have been proposed, but here, an example using four types of pilot signals will be explained. FIG. 1 shows the principle diagram. (1) is a magnetic tape that runs in the direction of arrow (a), and an anti magnetic head that runs in the direction of arrow (b) - (1, OY) ~ (1,08
11.) are each recorded by recording one field of the video signal at a predetermined position. In the recorded recording track (video track), (101
) (each track I″i of 1031 (105) (107)
@11 recording wrinkles with a video head having an azimuth angle of ε[ν1 (assumed to be A azimuth), (102) (1o4) (
106) (108) Each track has a 2nd azimuth pawl (assumed to be B azimuth) in the video head. On the other hand, the tracks (101) and (105) have fl, and the tracks (102 and 106) have f2 and (
103) (107) track f ke f4, (104) (
108) on the tfs track.

Pilot signals of different frequencies are superimposed and recorded on a primary periodic basis with the video signal, and these
The frequency around 41 is usually set to a frequency O that is 6 times, 7 times, 9 times, or 10 times as high as a certain frequency fo.

FIG. 1(a) shows a recording track (103) connected to a magnetic head (
The pilot signal of f4 (=10fo) is superimposed and recorded on the track (103), and there is a completely on-track state F, so f, (=7f, ), f, (=9fo) pilot signal crosstalk clear and almost the same level IF-1x
-I am.

FIG. 1(b) shows a state in which the magnetic head 00 is mistracked forward (with the tape traveling direction as the front) with respect to the recording track r103), and the crosstalk level of the pilot signal ft > f , has become a VC. The crosstalk level of the high lot signal, which indicates that the magnetic head 00 is mistracking backward with respect to the recording track (103) in FIG. 1(C), is f2 <
It is f3. At the time of reproduction, the pilot signal component (f, , f, ) is extracted from the reproduced RF signal by a filter (f4 in the condition shown in No. 11m(a)K).
3〉fl at f2 + and extracted at a level of f2 = fs), which is a signal having the same frequency as the pilot signal recorded on the track to be reproduced and is generated by a reference signal generator. (hereinafter referred to as the reference signal) is input to a multiplier and the difference frequency between the reference signal (f in Fig. 1) and the regenerated pilot signal is taken out, lfl'41 = 16fg 10fol =
4fo ” ' ■lf2 '41 =
l7fo 1ofol = 3f6...
■1f8-f,l = 19fo -10fol =
fo ... ■lf4 '41 = 1
10fo - 10fal = O... ■ Among these, fo and 3fo are band pass filters (BP'F
) to detect mistracks in the recorded tracks to be played.

In other words, there are many crosstalks of f2 in Figure 1I (crosstalk of f2 in bl), so the level is 3fn > level of fo In sentence 11, sentence 1(c), there are many crosstalks of f3, so 3f, Figure 2 shows the relationship between the level of < the level of fO. Figure 2 shows the magnetic tape t1.
) runs, the magnetic head changes I', l[1 track. I prayed! Indicates the offshore, and the reference signal V3 vibrator i
, t fs (=9 fo ), and the difference frequency between the crosstalk component of the pilot signal from the adjacent track and the reference signal f is 1f4-fsl' = +10fO-9foj = f from the front.
o 10. ■From the rear If+-fs I = 16fn -9fnl = 3
fo ... becomes ■. In addition, Figure 2 (
The magnetic head (11) in a) is shown in Fig. 1 (a). 1 (second azimuth angle CB azimuth different from j).

FIG. 2(tl) shows a state updated one track further from FIG. 2(a), where the reference signal is f+ (=6fn), and the difference frequency between the pilot signal and the reference signal is lfs r, l=19fn 6fn l=3
fn... ■From the rear: lf2 fl" 17fn 6fnl = fn
...■Similarly, in Figure 2 (0), If+ +21 = 16fn-7foj-fn from the front
... ■From the rear lf4- +21 = 110fo -7fnl
= 3fn ・ ・ '@The frequency of fn+3fn due to the crosstalk of the pilot signal of the VC@contact track is 14, and the levels are compared to obtain the tracking error voltage of the magnetic head.

Figure 3 is a block diagram of a circuit that generates a tracking error of 11 degrees Celsius. Ofl till is a head amplifier that increases the RF signal by +121031, and is referred to as a low-pass filter (LPF) +14i. Only the pilot signal component in the RF multiplied signal is extracted. A reference signal generator consisting of an oscillator that generates reference signals f1 to f4 in synchronization with the rotation of the 1tFit magnetic head (l[) ill.The pilot signal and the reference signal are manually multiplied by the multiplier j161F to obtain the above formulas Extract the difference frequency S number component between the reference signal and each pilot signal such as -1
Of these, f. +3fn component to band pass filter c
Hereinafter referred to as BPF1) (1η
After double-wave rectification with f+9) (hereinafter referred to as FDFiT), the level is compared with LPF (smoothing is performed with 211+22, and a comparator diagram consisting of a differential amplifier). , (24
, multiplied by 10 anti-reversal margin profit, and pα1liZ(a
)-Se+l/', Fig. 2(a) (1))
II) (B azimuth) When scanning with the track 1", in Figure 11 (a) and 2r9 (b), fo is 3fO1 from the front than in the front, and in Figure 2 (a) ((in 1, the front Since the crosstalk components of the pilot signal from the front side fo and the rear side 3fO are obtained alternately for each field, the output obtained from the inverting amplifier (comparator 241) is inverted and the output from the rotating magnetic head O(j A head switching pulse (a rectangular wave that switches between high and low for each field) synchronized with the rotational phase of Ill is used to correct the switch (turning off two members and turning one off) to obtain the tracking error m pressure.

FIG. 4 is a block diagram of a circuit that processes the tracking error m pressure and creates an electric signal for tracking the electro-mechanical transducer to a predetermined track, page 51, page 1, page 41.
+ [Is a waveform diagram of each part of the circuit block shown. A tracking error voltage proportional to the tracking error is sent to a sample and hold circuit (hereinafter referred to as S, H) (2η) and an analog switch 128 + (29)π,
, S, I((21'i+ +27), Figure 5(a)
h obtained with the timing of the head switching pulse shown in
Tracking errors if and EE (FIG. 5(b)) are sampled and held using song ring pulse A (51a(0)) or song ring pulse B (FIG. 5(d)). During the low level period of the head switch bus, the channel magnetic head 0 (1 is Q'!Ki tape (
1), and a non-contact period in which the B channel magnetic head (11) does not touch. During the high level period, the magnetic head (1
1) is in contact, and the magnetic '... (head (1 (J is the non-contact period. Tracking error 1; Voltage)
Magnetic head 0 (Yu's tape contact period is hold lie 7,
On the other hand, the analog switch (28) is the terminal (1)) (c)
Since it is opened and closed, the dragging error voltage is the output d of the output A shown in the 51st two (e) K.
il, L P F 1:lf, 1. Pass through the drive circuit t:) 11 and ``electrical-mechanical change J@''4ξ子 fi4
1 'V4 i.

The voltage is amplified until the pressure drive I〆11 is completed 17, and the magnetic head +1 (J≠; Control the IF fljlJ to ensure on-track.Next, set the magnetic head +
In the non-concubine period of 11, the analog switch (28) closes between the terminals (a) and (0), and the terminals B, H(7(il V
After sampling, the fr tracking error voltage is outputted via analog switch 4 as LPFj:jO]+1rhuman power Jl, LPF ta+j).
(With the time constant of Nll, (to) in Figure 5 (θ))
As the sampling error voltage (g) approaches the sampling error voltage (g), 〈9 this 'lfn pressure (g) is equal to the voltage), etc. 1, 1. -h,
The same goes for the B channel, and in the end, the initial position of the electro-mechanical transducer +341 f351 is memorized during the tape contact period of the magnetic head +lU, and returned to the memory position fif7 during the non-contact period. There is. In FIG. 4, 7e is a sampling pulse generator.

To give an overview, extract the pilot signal from the reproduced signal obtained by the magnetic head output (11), and select the recording track to be reproduced for the reference signals f1 to f of the reference signal generator (16). The deviation between the magnetic head UUO and the magnetic head UUO is obtained as a tracking error voltage, and this tracking error voltage is processed and amplified to lower the tracking error voltage. It constitutes a closed loop feedback control system that drives and controls the conversion element IC (51).

Next, the operation (special reproduction function) V of the control system when the magnetic tape (1) is reproduced at an arbitrary tape speed different from that during recording will be explained. In the above control system, any tape speed that varies during recording can be controlled by the electro-mechanical variable element t: +
41 1. (5i is the standard A word generator, 15) is the busy base J1A Iha number f, ~ f4 and Masa I] - Nokuirot signal of frequency? Ontra-tick and scan the closest track among the recorded tracks. :4 6 The sound of magnetic tape (1) running like Noh? , the standard i-cod gin is f,
K 1 0 η of the magnetic head 011 with constant alignment
1, In 1, (8) to (d) output the initial position of the magnetic head signal i (1' (3σ for diagonal lines) 1 - 1') K to the output signal f. , to C4i. 'On-track to the recorded track (105). , (θ)(f
) Deke (traveling of i1 multi-tape (1) (from rf to magnetic, so)' (II C7) Initial j1 guard 1t: f K nearest f,) rack becomes truck (109 >) .K on track.

Is the 71st v1 x+ that doesn't make the field regeneration accent 1 brighter?
．． It is a "↓" diagram, and the turn is turned and the stone 8 is turned to the throat 0 (). Nobumasa Tora-Tsuku, or if you want to record it in Tora-Tsuku, choose the first one you have (σ)ノζiro-sotoi-ku-masan-saku, here it is an odd-number Tora-Tsuku, which is hchi. f.

When using C4 by sequentially adding 1, Jl 1f/3@. (F
12 are shown. Regarding the switching order of reference signals &
``Depending on your answer in special playback mode, for example, 1/
When there are 3 throws and 11 points, the switching method is to run several tracks three times (-/fL) and move to the next odd-numbered track [-1-].

Figure 8 (b) to (d) ke 1/3 slot is electric at once
1(1 multi(JP7, conversion element 1: (41 applied to a'ii), (horn signal waveform, reference signal f,,
The switching timing of f is appropriate; fi-i+(b)
The average voltage is O (zero) (': near 1 Vre, but
Inappropriate (switching timing is early or late)
C) Positive or negative clear stream 1-1 as in (d)
t. Ll component is applied. Electrical-mechanical conversion element 1341
13! Among Il, there is a ball box represented by ζf such as bimorph. Applying a self-current Ichikawa current to the element and causing it to continue is generally considered undesirable in terms of the life of the element and deterioration of sensitivity.

Note that the 81st generation 1 (a) is a head switching pulse. Object of the Invention The present invention eliminates the above-mentioned drawbacks of the prior art, and provides a tracking device that prevents the application of pressure to a direct current to an electro-mechanical transformer. purpose.

Structure of the Invention In order to determine the purpose of the present invention, the tracking tie of the present invention is placed, and the video signal is transferred to the co-rotating magnetic field using the
Magnetic recorder F-slope J,, -#: Disconnected inscription [1 recording track group as H A pilot signal for tracking control is superimposed on a video signal and sequentially recorded on each track, and at the time of 11th generation, the pilot signal is reproduced from the recording tracks that are adjacent to the recording track before and after the recording track to be reproduced. It is equipped with a tracking device that detects tracking errors based on the level difference of the talk signal and controls the relative positional deviation between the recording track and the rotating magnetic head, and superimposes it on the video signal for each recording track to be reproduced during reproduction. a base thread signal generation circuit that generates a reference signal having the same frequency as the pilot signal recorded on the Ni1; a switching means that generates a frequency switching timing signal of the specified reference signal for each recording track; and the rotating magnetic head. an electro-mechanical transducer that displaces the mechanical position ii.7 in one direction of the recording track in a direction perpendicular to the recording track; feedback control means for tracking the rotary magnetic head on a recording track by supplying a corresponding electric signal to the recording track; In other words, according to the present invention, when applying driving pressure a to a chair-mechanical conversion element such as a bimorph, the switching timing signal C of the reference signal or less is simulated. (referred to as control signal)
is generated according to the DC component of the driving ton field, and the
This prevents direct current voltage from being applied to the mechanical transducer, thereby preventing the sensitivity of the mechanical transducer from decreasing and extending its life.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Figure 9 is a strategic configuration diagram of VTR, +4011
411 is a magnetic head, electro-mechanical conversion element +421
+431, and these and a magnet for rotational phase detection) 1441/45+ melting rotary disk (integrated with the fence and rotationally driven by a 1-gal flow motor 14'711/r. The above magnet 1441145) K compatible A DC motor J471 is installed between the rotational phase detectors.
Ff Frequency voice: machine t4! 1) is supplied to the output signal p of the oscillation circuit (N is the disk control circuit 61), and controls the rotational speed and rotational phase of the DC motor (471).The magnetic tape I!i2 is connected to the capstan ( 53) and pinch roller (see arrow (from 541r)
A). The capstan 63) is driven by a DC motor (r, 81) via a pulley base), a belt 1561, and a pulley (5η.
is controlled by the capstan control circuit i, 'i9), +e+++ is a DC motor! 5R) The output is amplified by the capstan FG amplification f611 with the FJ412 attached to the frequency sleeper. - is the tracking error control circuit, and the circuit inside the broken line in Figures 3 and 4 is the tracking error control circuit. The circuit configuration is the same, and the function is clear from the explanation of the conventional example, so the explanation will be omitted here.The part surrounded by a square is the main part of the present invention.
MIX of 431 5WD-1 pressure (before amplification) 2 channels
They are mixed at the circuit branch, and the DC voltage component is taken out using the LPF. The ring is a pseudo control signal generation circuit,
The output of the capstan FG amplifier (61) is frequency-divided to obtain a fade control signal as 't4), and the frequency division ratio is changed according to the DC spiral pressure component.

The pseudo control signal will be explained in detail later. ! As stated in TI, the 9th and 9th circuits switch the firing frequency of the reference signal generator at the same timing as the head switching pulse.
In the figure, (7+1 is the head switching pulse generation circuit, (721+73) is the drive circuit, (74+
+75) is a head amp.

No. ion shows a specific example of the circuit in the broken line () in Fig. 9, where a resistor (R,) (R,) and a capacitor (C3) form an M circuit (G) and an LPF (2). , to the line)
A DC voltage component is output. Resistance (R8) ~ (R and calculation increase, 6 circuits, 2 threshold points C (support)
It forms a comparator circuit with a pressure value of
If the voltage on the line) is higher than the voltage on the line, then the operational amplifier 6
The output of the operational amplifier 6η wheel is at a high level, and if it is an intermediate value between the points (lower than OFF, the output of the operational amplifier wheel is high level, and the point is on), the outputs of the operational amplifier 6η wheel are both at a low level. Divide the output of the capstan FG amplifier (61) with a frequency divider (counter)! i! +1, but the number of performances increased by 1111
．． % meter a71 (l turbidity (7) logic circuit QI with output value
By changing the preset value of the counter from JK, the frequency division ratio is completely changed (6) (9-digit reference signal 41 raw circuit).

The 11th button indicates the frequency switching timing of the basic b signal generation circuit 9, and (9) is the head switching pulse. At the timing of the edge (y) of the next head switching pulse of the reference signal +-f power generation circuit This is to prevent the track from being updated and obtain a clear screen.This is to prevent the oscillation frequency from generating ft and fs with only fI + f4 and realize in-field generation. From the explanation of FIG. 7, it is tomorrow.

Figure 12 shows the changes in the pseudo control sacrum due to the peak of () on the 101st line, and the circuit within the dashed line (to)) shows the change in the pseudo control sacrum with respect to the vicinity of 1Vac. As the voltage rises, the frequency division ratio increases and the DC voltage applied to the mechanical converter +4Z 1431 decreases. Among the voltage waveforms supplied to the electro-mechanical transducer, the harmful direct current voltage component can be minimized, thereby preventing a decrease in sensitivity of the electro-mechanical transducer and extending its life.

[Brief explanation of the drawing]

214 yen Figure 1 and Figure 2 (Explanatory diagram of the relationship between the position of the magnetic head and the crosstalk of the pilot signal recorded on the track. Figure 3 is a circuit that obtains the tracking error voltage from the pilot signal that is different from the conventional device. 1351 is a circuit block diagram of a circuit that obtains the drive voltage waveform applied to the electro-mechanical conversion element from the tracking error voltage in the conventional device 2, and FIG. 1351 is a waveform diagram of each part of the circuit shown in FIG. 4. , FIGS. 6 and 7 are explanatory diagrams showing the relationship between the reference signal and the recording track that is tracked on the magnetic head, FIG. 8 is the relationship between the driving waveforms of the electro-mechanical transducer, and FIGS. Figure 12 shows an embodiment of the present invention.
) ㅅ1 Schematic configuration 1 1, 101st circuit main part circuit diagram, 1st
1 and 12 are the 1st QI; (each part i of the circuit shown in 1M)
It is JV type 1ㅅ1. (52)...Magnetic tape, (Seki 1...Imebe 161)...Capstan FG amplifier, (6'2
...Tracking error control [r! 1st road, q9...
M engineering x circuit, (2)...Low pass filter,
・・pseudo control signal generation circuit, lock・・reference signal generation circuit, 6h19・・explosion υrt) amplifier, ←)・・・
Frequency divider, C,'+1...logic circuit, 1711...
・Head switching noise generation circuit agent Yoshihiro Moriki Fig. 1 Fig. 2 Fig. 3 Fig. C (22- Fig. 7 6'j ff Fig. f2 = 124-

Claims (1)

[Scope of Claims] 1. A magnetic recording and reproducing apparatus that records and reproduces video signals as a group of discontinuous recording tracks on a magnetic tape using a rotating magnetic head is provided. The reproduction tracking control pilot signals of different frequencies are superimposed on the video signal (C) and sequentially recorded on each track,
At the time of reproduction, f reproduces from the distribution tracks adjacent to the front and rear of the distribution track to be reproduced, and detects the tracking error voltage by the level difference of the crosstalk signal of the high lot signal, and detects the tracking error voltage from the recording track and the rotating magnetic head. A tracking wheel for controlling the relative positional deviation between the reference signal and the reference signal, which generates a reference signal having the same wave number as the pilot signal recorded superimposed on the video signal on each recording track to be reproduced during playback. a signal generating circuit; a switching means for generating a frequency switching timing signal of the reference signal for each recording track; and a mechanical position of the rotating magnetic head substantially perpendicular to the width direction of the recording track. an electro-mechanical conversion element for displacing the element; a feedback control means for supplying an electric signal corresponding to the tracking error voltage to the electro-mechanical conversion element to cause the rotating magnetic head to track the second recording track; and the electro-mechanical conversion element. and control means for controlling the switching means so that a DC voltage component of the electric signal supplied to and subtracted from the electric signal is minimized. 2. The control means for controlling the switching means is configured to use a signal obtained by frequency-dividing the capstan FG signal generated from a frequency generator synchronized with the rotational phase of the magnetic tape and drive capstan motor. Tracking device @8 according to item 1, a control means for controlling the switching means, changing the frequency division ratio of the capstan FG signal according to the DC voltage component of the electric signal waveform supplied to the electro-mechanical conversion element. A tracking device according to claim 2 of the present invention.