JPS59172112A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To remove the bad influence exerting on a tracking servo due to the expansion and contraction of a recording medium and to improve the packing density by applying tracking servo by utilizing the differential output between a main head and auxiliary head for detecting tracking having the same azimuth as the main head has. CONSTITUTION:At the time of recording, a vertical synchronizing signal VD is extracted at a synchronizing separator circuit 2 from a video signal from an input terminal 1 and supplied to a drum servo circuit 4 after it is frequency- divided into 1/2 at a framing control circuit 3. The drum servo circuit 4 compares the inputted vertical synchronizing signal with, for example, a PG signal obtained by detecting the output from a PG coil 5 fitted to a rotary magnetic head shaft with a PG detector 6, and applies phase servo to a drum motor 7 in accordance with a compared error signal obtained by the comparison. Namely, when tracking lag occurs due to the expansion, contraction, etc., of a tape, the delayed amount of a control signal from a reproducing amplifier 16 is changed in accordance with the condition of the tracking lag by the compared error signal, and the tracking is controlled. Therefore, tracking lag can be corrected surely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a magnetic recording/reproducing apparatus suitable for use in recording information on a recording medium such as a magnetic disk or magnetic tape.

Background Art and Problems It is well known that when recording information on a recording medium such as a magnetic disk or magnetic tape, a so-called azimuth recording method in which a guard band is omitted is used to increase the recording density. This enables high-density recording and reproduction. And what about the tracking sensor during playback with the conventional device?
The control (CTL) signal recorded in advance on a predetermined portion of the recording medium during recording is compared with a reference signal equivalent to a vertical synchronization signal from a built-in reference signal oscillator, and control is performed using the comparison error signal. The relative position of the vertical synchronization signal within the signal track with respect to the head position is always kept constant.

However, what about conventional tracking like this? In this method, if the interval between the control signal and the vertical synchronization signal is not constant due to expansion and contraction of the recording medium due to temperature changes, compatibility between sets, or mechanical accuracy in tracking adjustment, the head and recording medium may This system had some drawbacks, such as the sensor locking up without proper tracking (just tracking).

Also, what about traditional tracking servers? In this method, even if the above-mentioned tracking deviation occurs, it cannot be corrected, so even if the above-mentioned factors are added to the siryt'' mechanism, there is a limit to which tracking deviation can be tolerated without affecting the reproduced signal. Therefore, there is a limit to increasing the recording density in the track width direction.

Purpose of the Invention In view of the above, the present invention provides a magnetic recording system capable of improving recording density by eliminating adverse effects on tracking serve due to various factors such as expansion and contraction of recording media, compatibility between sets, and mechanical accuracy. The present invention provides a playback device.

Summary of the Invention The present invention includes a main head that scans an azimuth-recorded track, and a tracking detection head that has the same azimuth as the main head and is arranged to be equidistantly located at the displacement point of the adjacent track. The tracking sensor is equipped with an auxiliary head, and a tracking sensor is generated by the difference output between the main head and the auxiliary head. This is a magnetic recording and reproducing device characterized by a magnetic recording and reproducing device that is characterized by a magnetic recording and reproducing device that eliminates adverse effects on tracking sensors due to various factors such as expansion and contraction of the recording medium, compatibility between sets, and mechanical precision, and improves recording density. Improved.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 6.

FIG. 1 shows an example in which the present invention is applied to a magnetic recording/reproducing apparatus using a magnetic tape as a recording medium. It is also assumed that signal tracks in different azimuth directions are sequentially recorded without guard bands.

In the figure, (1) is an input terminal to which a video signal is supplied, and during recording, a vertical synchronization signal (VD) is extracted from the video signal from this input terminal (1) in a synchronization separation circuit (2). The frequency is divided by μ in the frame control circuit (3) and then supplied to the drum servo circuit (4).

The drum sensor circuit (4) detects this input vertical synchronization signal and, for example, the output from a PG coil (5) attached to a rotating magnetic head shaft (not shown) with a PG detector (6). Compare the PG multiplication signals, apply phase servo to the drum motor (7) according to the comparison error signal, apply speed servo to the drum motor (7) based on the above-mentioned PG multiplication signal, and control the drum motor (7). The phase and rotation speed are kept constant.

Also, for example, an FG double signal from a frequency generator (FG) (8) attached to the capstan e flywheel is amplified by the F'G amplifier (9) and supplied to the capstan servo circuit αQ, and this capstan servo Circuit αQ
A speed sensor is applied to the capstan motor (ell) so that the tape speed is constant due to the output of
By locking the double signal, a phase shift is applied to stabilize the tape speed during recording.

Note that during this recording, the W-divided vertical synchronization signal from the framing control circuit (3) is used as a control (CTL) signal.
After being amplified as a signal by the CTL recording amplifier (6), it is sent to the control head α via the contact R side of the switch (to).
→ and recorded on a predetermined portion of the tape T.

On the other hand, during playback, a speed servo is applied to the drum motor (7) by the output of the drum servo circuit (4) based on the PG multiplied signal (5) from the PG detector (6), and the above-mentioned PG multiplied The drum servo circuit (4) compares the signal with a reference signal equivalent to a vertical synchronization signal generated by counting down a 3.58 MHz clock signal in the built-in reference signal generator α→, and generates the comparison error signal. A phaser is applied to the sitram motor (7) to keep the rotation speed and phase of the drum (not shown) constant.

Further, the FG double signal from the FG amplifier (9) is supplied to the capstan servo circuit OI to detect the tape speed, and a speed servo is applied to the capstan motor αη so that the tape speed is constant. On the other hand, the reference signal generator (
The reference signal from c) is supplied to the capstancer circuit 01 via the framing control circuit (3), and
Control head←→The control signal reproduced from the tape T is supplied to the CTL reproduction amplifier QI via the contact P side of the switch (B), where it is amplified and amplified by the variable delay circuit CI for post-mortem tracking control. The capstancer is supplied to the circuit α1 (6) through 5 and compared with the above-mentioned reference signal, and the comparison error signal applies a phase check to the υcazostan motor α, and this phase check However, the above-mentioned speed servo is used for tracking during playback.

According to the present invention, an auxiliary head for tracking detection having the same azimuth as that of the magnetic head is provided adjacent to one of the plurality of rotary magnetic heads for recording and reproducing in a predetermined positional relationship. For example, in this embodiment, if one of the two rotating magnetic heads (main head) is I (A) as shown in FIG. A head Hc as an auxiliary head is provided adjacent to the head HA, and when the head HA is just tracking, for example, a track ■ on the tape T, the head Hc tracks both the track ■ and the adjacent track ■. The heads HA and Hc are arranged so as to maintain a contact area of approximately 50%.Here, the azimuth direction of the track (2) with which both the heads HA and Hc are in contact is the same as that of the heads HA and Hc.
Although the head Hc is in the same direction as the track ■, the head Hc is in contact with the track ■ in a different direction, so this head Hc cannot obtain the playback output from the track ■, and Only the reproduced output can be obtained, and moreover, only about 50% of the output level of the head HA can be obtained.

That is, when the head HA is just tracking, the output of each head is 1, and the output of the head Hc is 0.5.

The output of the head HA arranged in such a predetermined positional relationship is amplified by the RF antenna M, and then sent to the enperoso detector (
(to)) and is supplied to one input side of the comparator circuit. The output of the head Hc is amplified by the RF amplifier Q), detected by the enperoso detector, and supplied to the DC amplifier, where it is amplified twice and then compared to the comparator circuit (
1) is supplied to the other input side of 1). Therefore, during just tracking, signals of the same level (same polarity) are supplied to both input sides of the comparator circuit (1), and this is just tracking.
) Used as a standard when racking.

The output of the comparison circuit is supplied as a correction signal to the variable delay circuit α of the two tracking circuits via the low-pass filter (C) and the buffer circuit (C). In other words, during just tracking, both input sides of the comparator circuit are supplied with signals of the same level as described above, so no comparison error signal is obtained at the output side, and therefore the variable delay circuit α power is Even if the tracking position is adjusted to the best point at the initial setting, if a comparison error signal appears on the output side of the comparator circuit (1), tracking deviation may occur due to expansion and contraction of the υ tape. When this occurs, the comparison error signal is used to vary the amount of delay of the control signal from the reproduction amplifier α depending on the state of tracking deviation, thereby performing tracking control.

For example, as shown in FIG. 2, if the tape T runs too fast relative to heads HA and I(c),
The output level changes depending on the amount of deviation in the relative position of the head and tape.For example, the amount of deviation in the relative position of the head and tape for one track is divided into 8 (9) equal parts, and the output level is O for just tracking, and head HA for just tracking. If the track ■ is completely shifted from the track ■ (the figure shows that the track ■ is shifted as shown by the broken line with respect to the head HA) is 8, then the head 1 ( As shown in FIG. 3, the output levels of A and H8 both decrease as the amount of relative positional deviation increases, and the rate of decrease is approximately higher for the output of the head HA than for the output of the head Hc. This is a reduction rate of 50%.In FIG. 3, the characteristic indicated by the broken line represents the level change after the output of the head H9 is doubled by the DC amplifier.

Therefore, even though the levels of the outputs from heads I (J, and Hc) supplied to each input side of the just tracking comparison circuit are equal, and the comparison error signal is zero, as described above, Qi 7'T runs fast υ
When a deviation occurs in the tracking state of the track and head, that is, in the relative position of the head and tape, a comparison error signal corresponding to this deviation is output to the comparator circuit, and this comparison error signal controls the α force of the variable delay circuit. The amount of delay of the signal is controlled (10), and based on the output from the variable delay circuit α, the capstaff sensor 2 circuit α1 controls the casing stan motor 0.
A tracking serve is applied so that the relative speed between the head and the tape is constant with respect to η.

In addition, as shown in FIG. 4, if the tape T runs too slowly relative to the heads HA and Hc, the heads HA and H
Each output level of 6 changes as shown in FIG. That is, as the amount of relative positional deviation between the head and the tape increases, the output level of head HA gradually decreases, whereas the output level of head Hc is approximately equal to head H9 when the relative positional deviation amount is between 0 and 4. Although the output level increases to the maximum output level of , it decreases to the original level during just tracking between 4 and 8. This change in the output level of the head H8 is caused by the fact that during just tracking (when the amount of deviation is 0) the head Hc scans the track ■ of the same azimuth by y2 (the right half in the drawing), as shown in Fig. 4. This is because when the deviation amount is 4, the entire area of the track 2 is scanned, and when the deviation amount is 8, the remaining V2 of the track 2 (the left half in the drawing) is scanned again. In addition, in FIG. 5, the characteristics indicated by the broken line are for the head H.
This shows the level change after the output of c is doubled by the DC amplifier (e).

Therefore, as described above, when the tape T travels slowly with respect to the heads HA and H6, a deviation occurs in the relative position of the head and the tape, and a comparison error signal corresponding to the deviation is transmitted to the comparator circuit.
Based on this comparison error signal, the variable delay circuit α and the capstanchey as described above control the relative speed of the head and the tape to be constant with respect to the capstan motor ell) via the circuit α1 etc. Tracking sir is applied.

As described above, in this embodiment, the auxiliary head for tracking detection, which is adjacent to one of the plurality of rotating magnetic heads and has the same azimuth as this magnetic head, is positioned equidistantly on the adjacent track during just tracking. The relative position between the position sensor and the head is detected based on the output difference between both heads, and the detection signal is fed back to the tracking serve circuit, thereby ensuring that tracking deviations due to tape expansion and contraction are avoided. Can be corrected.

FIG. 6 shows an example in which the present invention is applied to a magnetic recording/reproducing device using a magnetic disk as a recording medium.
On the magnetic disk D, two magnetic heads HA and HB arranged in series on the same track and having different azimuth directions are moved in the radial direction of the disk and alternately switched for each track. It is assumed that signal tracks are recorded sequentially without bands.

In this embodiment as well, one of the heads HA and H, for example, the auxiliary head Hc for tracking detection having the same azimuth as the head HB, is attached to both adjacent tracks in the same amount, that is, approximately 5
It is arranged adjacent to the head Hc so as to maintain a contact area of 0%. In this case as well, when the head HB is just tracking, the output of each head is 0.5 if the output of the head H is 1, and the output of the head Hc is 0.5, depending on the relative position of the head and the disk. The difference in output changes as described above. Note that this head Hc is not used during recording, but is used only during (13) reproduction.

The output of the head HB arranged in such a predetermined positional relationship is amplified by RF amplifier 0, detected by envelope detector 0, and supplied to one input side of the comparator circuit (G). In addition, the output of the head Hc is
After being amplified, it is detected by an enperoso detector (g) and supplied to a DC amplifier (b), where it is amplified twice and then supplied to the other input side of the comparison circuit (to). Therefore, during just tracking, signals of the same level (same polarity) are supplied to both input sides of the comparison circuit (to), and this is used as a reference during just tracking.

The output of the comparison circuit (to) is supplied to the DC amplifier (b) via the low-pass filter Of), and this DC amplifier (b)
Voltage signals of the same level but opposite polarity are supplied to a piezoelectric element (b) such as a bimorph, and the amount of displacement thereof is controlled in accordance with the applied voltage. Note that this piezoelectric element (to) has a head HA + H!, which is not shown in the figure. 1 and H
C is coupled via the head substrate etc., therefore, the piezoelectric element (A) is connected to the error signal (1) from the DC amplifier (B).
4) The head position is controlled by multiple controls.

For example, in FIG. 6, if the right side of the drawing is the inner circumferential direction and the left side is the outer circumferential direction with respect to the disk D, and the head position deviates in the inner circumferential direction with respect to the signal track, then the head H!
As in FIG. 3, the output levels of l and Hc both decrease as the relative positional deviation between the head and the disk increases.
Furthermore, the rate of decrease in the output of head HB is approximately 50 degrees lower than that of head Hc.

Also, if the head position deviates toward the outer circumference with respect to the signal track, the head H! The output level of l and Hc is the third
Head H as shown! The output of l decreases and the output of head Hc increases substantially. Therefore, these heads H and H
The change in the output level of 8, that is, the deviation in the relative position of the head and the disk, is taken out as an error signal to the output side of the comparison circuit 01, and this error signal is sent to the piezoelectric element via a loaf 4 filter (b) and a DC amplifier (b). (b) supply;
By changing the amount of displacement by the error amount, the head HB (and HA
), it is possible to always accurately track the signal track (15).

In this way, this embodiment can also provide substantially the same effects as those of the above embodiment.

Effects of the Invention As described above, according to the present invention, there is a main head that scans an azimuth-recorded track, and a head that has the same azimuth as this main head and is arranged so as to be positioned equally at adjacent track displacement points. Since the tracking chi is applied to the difference output from the auxiliary head for tracking detection,
Eliminates deviations in the relative position of the recording medium and the head, making it possible to keep their relative speed constant at all times, and eliminating tracking deviations due to various factors such as expansion and contraction of the recording medium, compatibility between sets, and mechanical precision in tracking adjustment. This makes it possible to prevent such adverse effects.

Furthermore, since the adverse effects caused by the above-mentioned factors are eliminated, the acceptable limit for tracking deviation can be made even stricter, and recording and reproduction at a higher density becomes possible.

(16)

[Brief explanation of drawings]

FIG. 1 is a system diagram showing one embodiment of this invention, FIGS. 2 to 5 are diagrams for explaining the operation of FIG. 1, and FIG. 6 is a system diagram showing another embodiment of this invention. It is a diagram. HA + HB is the magnetic head (main head), HC is the auxiliary head for tracking detection, T is the magnetic tape, D is the magnetic disk, αQ is the capstan serve circuit, ell)
is the capstan motor, α force is the variable delay circuit, (L,
(c), o]), (b) is RF Aan, α Samurai, (b)
, 0埠, (A) is an envelope detector, (A), (to)
is a comparison circuit, w, On, (b) is a DC amplifier, and (a) is a piezoelectric element. (17) ← `` '' 71- <t'''L-B and Mu' (Mulberry

Claims (1)

[Claims] A main head that scans the azimuth recorded track,
An auxiliary head for tracking detection is provided, which has the same azimuth as the main head and is arranged to be located equally at the displacement point of the adjacent track, and the main head and the auxiliary head A magnetic recording/reproducing device characterized in that a tracking serve is applied to the differential output.