JPS60253017A - Search operation controlling system of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce virtually an omission of information by controlling a transfer speed of a recording medium by a tracking error signal formed by a frequency signal varied so as to be successively equal to each frequency of plural pilot signals, and a pilot signal obtained from an adjacent track. CONSTITUTION:Four reproducing pilot signals f1-f4 whose high band component is eliminated by a low-pass filter 13 pass through an amplifier 14, and thereafter, are supplied to a mixer 15 and mixed with an output of a four frequency signal generating circuit 8, being the first frequency signal. From the output of the mixer 15, fH and 3fH components being the second and the third frequency signals are extracted by a band-pass filter 16 and 17, respectively, and thereafter, supplied to a detector 18 and 19. From the detector 18 and 19, a voltage corresponding to the signal level of the fH and 3fH components is outputted and applied to positive side and negative side input terminals, respectively, of a differential amplifier 20. From a signal switching circuit 21, the output of the differential amplifier 20 and the output of an inversional amplifier 22 are led out selectively, and become the output of a 4F error detector 11, namely, a tracking error signal.

Description

TECHNICAL FIELD The present invention relates to a search operation control method for a magnetic recording/reproducing device, and more particularly to a search operation control method for a magnetic recording/reproducing device that performs tracking control using a four-frequency tracking method.

BACKGROUND ART In a conventional magnetic recording/reproducing device (hereinafter referred to as VTR), a pulse signal (hereinafter referred to as a CTL signal) corresponding to drum rotation is sent to a control track provided along the edge of a magnetic tape during recording. The CTL signal is recorded at a fixed point, and during playback, the tape speed is controlled so that the phase of this CTL signal matches the drum phase using rainbow tracking control. However,
When the density of recorded information is increased, such as in the recently proposed SMI+JVTR, the tape speed generally becomes lower and the track pitch becomes narrower.

In such a case, with a magnetic flux responsive fixed head, the S/N ratio of the reproduced CTL signal deteriorates as the tape speed decreases, causing a problem that it is difficult to ensure sufficient tracking accuracy. For this reason, in the S-millimeter VTR, four pilot signals having different frequencies and a predetermined relationship are sequentially superimposed on the information signal and recorded, and tracking control is performed using the pilot signals read as crosstalk from adjacent tracks during playback. A so-called four-frequency tracking method is adopted. This is because the pilot signal is reproduced as it rotates, so it does not depend much on the tape speed.

In such s-millimeter V T and R, as with conventional V T R, in the search playback mode, the gutter scans the magnetic tape across several recording tracks, so simply increasing the tape speed will cause the tape to move away from adjacent tracks. Information is lost due to a drop in the signal level of the reproduced RF (corner EL) signal due to unmasked recording to remove Talostalk,
A problem arises in that a noise bar appears on the playback screen and the noise bar moves on the playback screen, making the playback screen very difficult to see.

SUMMARY OF THE INVENTION An object of the present invention is to provide a search operation control method for a magnetic recording/reproducing apparatus that can reduce the loss of information during the null reproduction mode.

A search operation control method for a magnetic recording/reproducing apparatus according to the present invention increases the transport speed of the recording medium by a predetermined number of times during recording, and makes the frequency equal to each frequency of a plurality of pilot signals sequentially at a period corresponding to the transport speed of the recording medium. forming a first frequency signal that varies such that the first frequency signal and two pilot signals obtained from adjacent tracks are mixed to form second and third frequency signals; A tracking error signal having an instantaneous level corresponding to the difference in signal level of the three frequency signals is formed, and the transport speed of the recording medium is controlled so that the average of the instantaneous levels of this tracking error signal is equal to a predetermined level. It is said that

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, a speed detection signal having a frequency corresponding to the rotational speed of a capstan motor 1 as a transfer means is supplied to a speed detector 2 and a phase difference detector 3. This speed detection signal is, for example, the rotation 7 yaf of the capstan motor 1]
・It is output from a Vinokuag (not shown) that detects the magnetic flux of a magnet (not shown) fixed to the. The speed detector 2 receives a command specifying a playback mode from an operation unit (not shown), for example, and generates a full voltage according to the frequency of the speed detection signal using a conversion coefficient corresponding to the specified playback mode. (frequency/voltage) converter, and the output of this F''/V converter is used as a speed error signal.The output of this speed detector 2 becomes the input power of the adder 4. The added output of the generator 4 becomes a rotation control signal for the capstan motor 1 via the driver 5.The output of a phase generator (not shown) fixed to the rotating drum motor is input to the phase difference detector 3. A head switching signal SWI) obtained from the reference A ε generation circuit 6 is supplied.

The phase difference detector 3 is configured to output a phase error signal obtained by adding 1 to the phase difference between the head sliding signal swP and the speed detection signal. The output of the phase difference detector 3 is supplied to the adder 4 via the switch S+1 which is turned on during recording. The head switching signal SWP is generated by the timing signal generation circuit 7.
is also supplied. Timing signal generation circuit 7 +'
j, operation unit (not shown) ↓A timing signal of a frequency corresponding to the specified playback mode is generated based on the all-head switching signal SWP in response to a command specifying the playback mode. . The timing signal output from this timing signal generation circuit 7 is supplied to a four-frequency signal generation circuit 8. The four-frequency signal generation circuit 8 generates 65fH17 each time the state of the timing signal changes.
It is configured to sequentially output four signals L−f+2 of 5fH, 1O5fH and 95fH (fH is the horizontal synchronization frequency).

The output of the 4-frequency signal generating circuit 8 is added as a pilot signal to an information signal, such as an FM signal including video information and audio information, by an adder 9 and then synthesized. B is applied and recorded on the magnetic tape T as a recording medium. In addition, the pilot signal is + f2 + fl + f
For example, if fl is recorded immediately before moving to the recording pause state, then when moving from the recording pause state to the recording state, it will be recorded in the above order starting with f2 when moving from the recording pause state to the recording state. A four-frequency signal generating circuit 8 is formed as shown in FIG.

Further, the error output of the 4F error detector 11, which is an error detector based on the 4-frequency dragging method, is supplied to the adder 4 via the switch S3, which is turned on during reproduction.

The 4F error detector 11 is supplied with an RF signal read from the magnetic tape T by the rotary heads A and B via the changeover switch 82 during reproduction. In the 4F error detector 11, the RF signal is amplified by a preamplifier 12, and then high-frequency components are removed by a low-pass filter 3 to extract four pilot signals f1 to f4. These reproduced pilot signals 11 to f4 are supplied to a mixer 15 after passing through an amplifier 14, where they are mixed with the output of a four-frequency signal generation circuit 8 as a first frequency multiplier. From the output of mixer 15, fH and 3fH components as second and third frequency multipliers are extracted by bandpass filters 16 and 17, respectively, and then supplied to detectors 18 and 19. The detectors 18 and 19 output voltages corresponding to the signal levels of the fH and 3fH components, which are applied to the positive and negative input terminals of the differential amplifier 20, respectively. The output of the differential amplifier 20 is directly applied to one input terminal of the signal switching circuit 21 and simultaneously applied to the other input terminal of the signal switching circuit 21 via an inverting amplifier 22. The output of the timing signal generation circuit 7 is applied to the control input terminal.The output of the differential amplifier 20 and the output of the inverting amplifier 22 are alternatively derived from the signal switching circuit 21 and output to the 4F error detector 11. It becomes an output, that is, a tracking error signal.

As shown in FIG. 2, the rotating heads A and Bi are fixed to the drum H at 180 degrees apart with respect to the rotating shaft so that they rotate together. Drum Hfi, vertical synchronization signal of input video signal or internal reference signal (e.g. 3.58MHz
It is designed to be rotationally driven in synchronization with a signal obtained by dividing the frequency of the subcarrier).

The magnetic tape Tfi is rotated by the capstan motor l, and the rotating heads A and B are rotated at a speed corresponding to the number of rotations of the nodes A and B.
Vc, and a plurality of recording tracks substantially parallel to each other are formed as shown in FIG. At the same time, one field of video information is recorded on each recording track, and the pilot signal is frequency multiplexed.
f2. The signals fl and f are switched for each recording track and recorded sequentially.

Corresponding to the rotation throat A to the track A in FIG. 3,
Track B corresponds to rotation throat B.

To the four pilot signals that are frequency multiplexed and recorded on these recording tracks along with video information etc. ~14 frequencies μ 65fH+ 75 for each, for l 05 f1+
+951H (horizontal synchronization layer e, number in flll), so
The following relationship holds true.

! , /, -f21=1.73-, f41=fo...(
1) lj2-131=1.7l-y41=3z, (2
) The frequencies of these four pilot signals are 10014
Hz to 16 KHz, and there is almost no loss due to azimuth, so not only the pilot signal recorded on the recording track being scanned by rotary knob A or B, but also the two tracks adjacent to this recording track. The two pilot signals respectively recorded in are also reproduced as crosstalk. The level of this crosstalk is approximately proportional to the width of the rotating head that is in contact with the adjacent track. Therefore, the relative position of the recording track in the vertical direction with respect to the recording track of rotation Q/DO can be detected by the difference in signal level of the two pilot signals reproduced as crosstalk.

Now, each recording track has a pilot signal of f++f2.
f3. Since the pilot signal is recorded sequentially in the order of f, if the pilot signal recorded on the recording track that the rotary head A or 1-jB is in contact with is 11, it is recorded on two adjacent tracks. Pilot signal d14
and f2. Then, the fH acid component and the 3fH component in the output of the mixer 15 correspond to f2 and f, respectively. Therefore, when the output of the differential amplifier 20 is at a positive level, the signal level of the uf2 component is shifted toward the recording track in the direction opposite to the tape running direction. Further, when the output of the differential amplifier 20 is at a negative level, the signal level of the 'is f4 component is large, which means that the rotational node has shifted in the tape running direction with respect to the recording track.

Next, if the pilot signal recorded on the recording track with which the rotation knob is in contact is 12, the pilot signal trJ recorded on the two adjacent tracks is
-f, and f3, and 9 and 3 in the output of mixer 15.
The fH components correspond to f and f3, respectively. Therefore, in this case, when the output of the differential amplifier 20 is at a positive level, the signal level of the f1 component is thick, that is, contrary to the above case, the rotation node is shifted in the tape running direction with respect to the recording track. Become. -i, differential amplifier 2
When the output of 0 is at a negative level, the signal level of the f3 component is thick, that is, the rotation throat is shifted in the direction opposite to the tape running direction with respect to the recording track.

Therefore, if the output of the differential amplifier 20 and the output of the inverting amplifier 22 are outputted alternately, a continuous error signal can be obtained. Trunking control will be performed.

The above explains the operation in normal playback mode, but
Next, the operation in the search playback mode will be explained.

Assuming that the tape speed in the search playback mode is nine times that in the normal playback mode, the head switching signal SWP as shown in FIG. The timing signal is shown in the same figure (D
) as shown below. Then, the 4-frequency signal generation circuit 8
The frequency of the output changes as shown in (E) of the same figure. At this time, the magnetic tape was transferred so that the pattern of the recording tracks observed from one of the positions of nodes A and B as shown in FIG. In this case, the tracking error signal becomes as shown in FIG. CF). That is, the tracking error signal at this time has a waveform in which eight sawtooth waves exist within the l field period, and the average level is Ov. The components of this tracking error signal that exist within the required band of the capstan system (several -1 Hz to tens of Hz) become a signal similar to a DC component with a level approximately equal to the average level, so that the tape speed does not change.

If the pattern of the recording trunk is as shown in the same figure (G),
1) If the rack pitch deviates in the tape running direction, the tracking error signal becomes as shown in FIG. Then, the tape speed decreases and the capstan motor 1 is driven and controlled so that the recording track pattern becomes as shown in the same figure (CJ).

If the recording track pattern deviates in the opposite direction to the tape running direction, the average level of the tracking error signal becomes negative, the tape speed increases, and the capstan motor is activated so that the recording track pattern returns to its original state. 1 is driven and controlled.

Therefore, the RF double signal level is always as shown in CB, 1 in the figure, and the position where the RF double signal level decreases is near the state transition point of the rotating drum reference signal SWP, that is, in and around the vertical synchronization signal section. Therefore, the noise bar appearing on the playback screen can be reduced and the position of the noise bar on the playback screen can be fixed.

Effects As detailed above, in the search operation control method of the magnetic recording/reproducing apparatus according to the present invention, the frequency changes so that the frequency becomes sequentially equal to each frequency of a plurality of pilot signals at a period corresponding to the transport speed of the recording medium. The transport speed of the recording medium is controlled by the tracking error signal formed by the signal and the pilot signal obtained from the adjacent track. Controlling the transport speed of the recording medium so that the pattern becomes a predetermined pattern,
By positioning the noise bar at a position where it does not appear on the playback screen, it is possible to reduce the amount of information missing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 shows a rotating throat A in the apparatus shown in FIG. FIG. 3 shows a recording track formed on a recording medium by the device shown in FIG. 1, and FIG. 4 shows the operation of the device shown in FIG. 1. FIG. Explanation of symbols of main parts l...Cab stan motor 8...Four frequency signal generation circuit 11...4F error detector Applicant Pioneer Co., Ltd. agent Patent attorney Rattan material Moto Hikomaku 2 Figure 3

Claims (1)

[Claims] at least two rotary nodules that rotate together; and rotation of the at least two rotary nodules along the at least two rotary nodules of the recording medium such that the at least two rotary heads alternately scan the recording medium. a transporting means for transporting at a speed corresponding to the speed, the plurality of recording tracks are formed in parallel to each other on the recording medium during recording, and at the same time, the plurality of recording trunks have different frequencies and are arranged in a predetermined relationship with each other. sequentially recording a plurality of pilot signals having a plurality of pilot signals obtained simultaneously from two recording tracks adjacent to one of the plurality of recording tracks being scanned by one of the at least two rotational nodes during reproduction; Fully controlling the relative position in the vertical direction of the recording track with respect to the recording l/thick of the rotating groove scanning the recording medium so that the signal levels of two of the plurality of pilot signals are equal to each other. A search operation control method for a magnetic recording/reproducing device, wherein the transport speed of the recording medium is multiplied by a predetermined number during recording, and the frequency is adjusted to each frequency of the plurality of pilot signals at a period corresponding to the transport speed. A first frequency multiple is formed whose V'C is successively changed to be equal, and a second frequency multiple is generated by mixing the first frequency multiple with two of the plurality of pilot signals obtained simultaneously from the two recording tracks. and forming a third frequency indoctrination number, said second and third
A tracking error signal having an instantaneous level equal to I is formed by the difference in the signal level of the frequency training signal, and the tracking error signal is
A search operation control method for a magnetic recording and reproducing apparatus, characterized in that the transfer speed is controlled g4 so that the average instantaneous level of the King error signal becomes equal to a predetermined level.