JPS60129917A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To ensure the stable tracking in a reproduction mode with a magnetic recording/reproducing deive which performs record and reproduction by means of a rotary magnetic head having the width smaller than the track pitch, by forming a pilot signal track at an area which so far serves as a guard band. CONSTITUTION:The head width W is set to all of the 1st and 2nd pairs of magnetic heads 2a/2b and 2c/2d. The heads 2c and 2d are attached at the position turned by 90 deg. to the heads 2a and 2b with a head level difference TP. The record is carried out successively by heads 2d, 2a, 2c and 2b to form alternately tracks 6a, 7a, 6b and 7b where the signals to be recorded are recorded and pilot signal tracks 8a, 9a, 8b and 9b where the pilot signals are recorded. A pilot signal track, e.g., the track 9a is recorded by the head 2d and also written double by heads 2a and 2b. Thus the track width is finally set at TP-W.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic recording and reproducing device, and particularly to a magnetic recording and reproducing device with improved tracking.

[Prior Art] Conventionally, in a rotating magnetic head type magnetic recording/reproducing device, a control signal method and a four-frequency pilot signal method have been adopted as tracking methods. Con 1~
In the roll signal system, a control signal is recorded on the controller 1-roll signal@1~rack using a fixed magnetic head and is reproduced. In addition, in the 4-frequency pilot h signal system, four pilot signals with different frequencies are switched for each track, multiplexed with the signal to be recorded, and recorded with a rotating magnetic head, and during playback, the rotating magnetic head is used. Tracking is performed using pilot signal components of adjacent tracks on both sides included in the reproduced signal. In order to achieve high-density magnetic recording and playback, there is a recent trend to reduce the tape speed and narrow the track pitch.As a tracking method, tracking is performed using information obtained from tracks recorded by a rotating magnetic head. 4
Frequency pilot signaling systems are becoming mainstream.

Here, some explanation will be added about the four-frequency pilot signal system using FIG. In FIG. 1, tracks 3a, 3b, 3c, 3d, and 3a are recorded on a magnetic tape 1 by a magnetic head 2a or a magnetic head (not shown), and each track has four pilot signals. f I , f2 + f8 and f4 are multiplexed and recorded on the recording signal to be recorded. Arrows A and B indicate the moving directions of the magnetic tape 1 and the magnetic disk 2a, respectively, TP is the track pitch, and W is the head width of the magnetic disk 2a.

When the track 3b shown in FIG. So,
When this method is adopted, the side read effect of the magnetic head is taken into consideration, and the relationship between the head width W of the magnetic head and the track pitch TP must be in the range W≧TP or W is slightly smaller than TP. .

FIG. 2 shows a case where the head width of the magnetic head is smaller than the track pitch, that is, when tracking is achieved with W < TP, and the pylon 1 signal of the adjacent track cannot be reproduced. Note that in FIG. 2, the same parts as in FIG. 1 are given the same reference numbers. In FIG. 2, in order to eliminate interference from adjacent tracks to signals to be recorded and reproduced, a guard band (non-recording band) 50 shown in diagonal lines in this figure is provided. It is difficult to achieve stable tracking using the frequency pilot signal system.

[Summary of the invention] This invention was made against this background.
Therefore, the main object of the present invention is to provide a magnetic recording and reproducing apparatus that can realize stable tracking during reproduction when recording and reproducing with a rotating magnetic head whose head width W is smaller than the track pitch TP. It is to provide.

To summarize the invention, a first set of rotary magnetic heads for recording and reproducing signals to be recorded and a second set of rotary magnetic heads for recording pilot signals are provided, and during recording,
In the case of only the first set of rotating magnetic heads, a pilot signal track is formed in the part that becomes the guard band, and during playback, two pilot signal tracks included in the reproduced signal by the first set of rotating magnetic heads are formed. This is a magnetic recording and reproducing device that performs tracking using pilot signals from

The purpose and other purposes and features of this invention are as follows:
It will become clearer from the following detailed description with reference to the drawings.

[Embodiment of the Invention] FIG. 3(a) is a diagram showing the arrangement of magnetic heads on the rotating drum 4 in an embodiment of the invention. The first set of magnetic heads 2a, 2b records signals to be recorded and reproduces signals to be recorded and pilot signals. The second set of magnetic helads 2c, 2d records pilot signals. Further, arrow C indicates the rotation direction of the rotating drum 40. Here,
The head widths of the first and second sets of magnetic heads are all W, and the second set of magnetic heads has a head step TP at a position rotated by 90 degrees with respect to the first set of magnetic heads. It shall be installed as follows.

FIG. 3(b) schematically shows a track pattern recorded on the magnetic tape 1 in an embodiment of the present invention. In FIG. 3(b), for convenience of illustration, each track is shown perpendicular to the moving direction of the magnetic tape. During recording, as shown in FIG. 3(b), the signals are sequentially recorded by the magnetic heads 2d, 2a, 2c, and 2b, and the signals to be recorded are recorded on the track 5a,
7a.

6b, 7b and pilot signal tracks 8a, 9a, 8b, 9b on which pilot signals are recorded are alternately formed. The magnetic head 2d in FIG. 3(b),
The rectangular broken line on the left side of 20 is the position of the magnetic head when the head height difference is O. The pilot signal track, e.g. 9a, is activated by a magnetic helad 2d.
Recording is performed with a track width W (head width of the magnetic head), but overwriting is performed by the magnetic heads 2a and 2b, and the final track width becomes Tp-W.

FIG. 4 is a schematic block diagram of a magnetic recording/reproducing circuit according to an embodiment of the present invention. Moreover, FIG. 5 is a time chill rate explaining the operation in one embodiment of the present invention. In FIG. 4, the input terminal 13 is connected to the recording amplifier 20.
The recording amplifier 20 is connected to a switch circuit 21 . The switch circuit 21 is connected to the magnetic heads 2a and 2b via a rotary transformer 19. Recording amplifier 2
O, the switch circuit 21, the rotary transformer 19, and the magnetic heads 2a and 2b constitute a recording signal recording circuit. During recording, a recording signal is input from the input terminal 13, and the recording signal is input to the recording amplifier 2.
After being amplified by the switch circuit 21. The information is recorded by the magnetic heads 2a and 2b via the rotary transformer 19. As shown in FIG. 5(a), when the head switching signal H8WI is at a high potential (hereinafter abbreviated as H), it is recorded by the magnetic head 2a, and when it is at a low potential (hereinafter abbreviated as "H"), it is recorded by the magnetic head 2a. It is assumed that recording is performed by head 2b. Input terminal 11 and input terminal 12 are switch circuit 1
4, and the switch circuit 14 is connected to a frequency dividing circuit 15. The frequency divider circuit 15 is connected to a cyclic frequency generator 16, which in turn is connected via a recording amplifier 17 to a switch circuit 18. The switch circuit 18 is connected to the magnetic heads 2c and 2d via a rotary transformer 19.

The cyclic frequency generator 16, the recording amplifier 17, the switch circuit 18, the rotary transformer 19, and the magnetic heads 2c and 2d constitute a pilot signal recording circuit.

The switch circuit 14 receives the head switching signal H8W2 input from the input terminal 11 and the head switching signal H8WI input from the input terminal 12, and outputs the head switching signal HS W 2 during recording. The output of the switch circuit 14 is divided into 1 by a frequency dividing circuit 15 as shown in FIG. 5(C).
The frequency is divided by /2. The head switching signal HS W2 is a signal for switching the magnetic heads 2c and 2d, and the pilot signal is a signal for switching the magnetic heads 2c and 2d when the head switching signal H8W2 is H.
C is recorded, and the edge of L is recorded by magnetic head 2d.
recorded by. Here, the pilot signals fx, f
Y is generated by the circulating frequency generator 16, and the pilot signals become pilot signals fx and fY depending on the outputs of the frequency dividing circuit 15 being H and L, respectively.

The pilot signal is amplified by a recording amplifier 17, then passed through a switch circuit 18 and a rotary transformer 19, and then recorded by magnetic heads 2c and 2d. Therefore, Fig. 5Cb),
As shown in (C), as a pilot signal, pilot signals rX and fY are alternately recorded every two fields, that is, every two pilot signal tracks.

The rotary transformer 19 is connected to a regenerative amplifier 22 via a switch circuit 21. Magnetic heads 2a, 2b, rotary transformer 19, switch circuit 2'1, and regenerative amplifier 2
2 constitutes a recording signal and pilot signal reproducing circuit. Furthermore, the regenerative amplifier 22 has a bandpass filter 23a.
and a bandpass filter 23b. The bandpass filter 23a passes through the subtracter 25 via the detector 24a.
– is connected to. Furthermore, the bandpass filter 23b is connected to a subtracter 25 via a detector 24b.

Subtractor 25 is connected to switch circuit 27 and inverting amplifier 26 , and inverting amplifier 26 is connected to switch circuit 27 . The switch circuit 27 is connected to a hold circuit 29 via a switch circuit 28, and the hold circuit 29 is connected to the output terminal 3O.

Bandpass filters 23a, 23b and a detector 24a,
24b, subtracter 25, inverting amplifier 26, and switch circuit 2
7.28 and the hold circuit 29 constitute a tracking error signal generating circuit. Further, the input terminal 12 is connected to the switch circuit] 4 and the switch 1 circuit 28, and the output of the frequency dividing circuit 15 is connected to the switch circuit 27. During reproduction, the recording signal and pilot signal reproduced by the magnetic heads 2a, 2b are transferred to the rotary transformer 19. After passing through the switch circuit 21 and being amplified by the regenerative amplifier 22, the signal is input to the tracking error signal generation circuit after the bandpass filters 23a and 23b and the signal regeneration circuit after the output terminal 31. Bandpass filter 23a, 2
3b separates only the pilot signal fx1 or fY component contained in the output of the regenerative amplifier, respectively. The signals f x and fY to the separated pilot 1 are envelope-detected by detectors 248 and 24 b, respectively, and their outputs are given to the subtracter 25 . The output of the subtracter 25 is the fifth
As shown in Figure (e), a switch circuit 27 that switches according to the output of the frequency divider circuit 15 outputs a signal with the same polarity, or a signal with the opposite polarity via an inverting amplifier 26, and outputs the signal to the next stage. It is output to the switch circuit 28. Note that the frequency dividing circuit 15 is connected to the input terminal 1 via the switch circuit 14.
The head switching signal H8W1 from No. 2 is input. Now, one input terminal of the switch circuit 28 is open. Therefore, the head switching signal - @ HS W
When 1 is H, the switch circuit 2 is connected to the hold circuit 29.
7 is input, and it is directly output from the output terminal 3o as a tracking error signal output. Also,
When the head switching signal)-18W1 is L, the input of the bold circuit 29 is open, and the head switching signal H3W
The output of the hold circuit 29 at the time when the signal 1 switches from H to L is held.

FIG. 6 is a diagram shown to explain in more detail the tracking operation in one embodiment of the invention. Note that in FIG. 6, the same parts as in FIG. 3 are given the same reference numbers. In FIG. 6, tracks 6a and 6b are recorded on the magnetic tape 1 by a magnetic head 2a, tracks 7a and 7b are recorded by a magnetic head 2b, and pilot signal tracks sa' and sb are recorded by a magnetic head 2C.
However, the pilot signal track 9a is detected by the magnetic herad 2d.
, 9b are recorded. At D in the figure, the magnetic tape 1 is in a state further advanced than the optimum tracking state, and the tape drive device is controlled so as to slightly slow down the tape speed.

Further, at E in the figure, the magnetic tape 1 is in a state lagging behind the optimal tracking state, and the tape drive device is controlled to slightly increase the tape speed. By the way, in both cases of Nori and E in the figure, the magnitude of the pilot signal is larger than that of the pilot signal fY, but as mentioned above, the polarity of the output of the subtracter 25 is inverted every two fields. 1 to racking is output as an error signal and -C is output, so the state shifts to the optimum 1 to racking state, respectively.

The frequency of the pilot signal has little effect on the recording and playback of the signal to be recorded, and
It is sufficient to select a frequency band within a frequency band that is easy to process. Also,
When the magnetic heads 2a and 2b have different azimuths, a low frequency may be selected so that the influence of the azimuth effect is small in reproducing the pilot signal.

In addition, in the above explanation, as a pilot signal,
Two pilot signals with different frequencies +y, f,
, but the purpose of the present invention can also be achieved by writing pilot signals intermittently using a single frequency and then equivalently obtaining two pilot signals by changing the writing position. . That is, it is sufficient to have two pilot signals.

Moreover, it goes without saying that the same applies even if the number of pilot signals is three or more. FIG. 7 shows a track pattern when four pi-one-shot signals are used. In this case, the configuration is similar to the conventional four-frequency pilot signal system.
Ranking control can be performed. Note that in FIG. 7, the same parts as in FIGS. 3 and 6 are given the same reference numbers.

Furthermore, when using this invention in a magnetic recording/reproducing device,
In the above embodiment, if the magnetic heads 2c and 2d have the same azimuth and are used during still and slow playback, it is possible to realize still and slow playback without blur.

[Effects of the Invention] As described above, according to the present invention, the pilot signal track is formed in the part that was conventionally used as a guard pad. In a magnetic recording and reproducing device that records and reproduces data using a head, stable tracking during reproduction can be performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating tracking when the head width of the magnetic head is larger than the track pitch in the conventional four-frequency pilot signal system. FIG. 2 is a diagram illustrating tracking when the head width of the magnetic head is smaller than the track pitch in the conventional four-frequency pilot signal system. FIG. 3 is a diagram schematically showing the arrangement of a magnetic head on a rotating drum and a track pattern recorded on a magnetic tape according to an embodiment of the present invention. FIG. 5 is a schematic block diagram of a magnetic recording/reproducing circuit in one embodiment. FIG. 5 is a time chart explaining the operation in one embodiment of the present invention. FIG. 6 is a tracking operation in one embodiment of the present invention. 7 is a diagram shown for further detailed explanation. FIG. 7 is a track pattern when four pilot signals are used in another embodiment of the present invention. In the figure, 1 is a magnetic tape; 2a and 2b are magnetic heads for recording signals to be recorded and reproducing signals to be recorded and pilot signals; 20 and 2d are magnetic heads for recording pilot signals; 4 is a rotating drum; 6a, 6b, 6
C is a track recorded by the magnetic head 2a, 7a
, 7b is the track recorded by the magnetic herad 2b,
8a, 8b, 8c are pilot signal tracks recorded by the magnetic head 2C, 9a, 9b are the magnetic herads 2d
Pilot signal track recorded by, 14.1
8.21 is a switch circuit, 15 is a frequency dividing circuit, 16 is a circulating frequency generator, 17 is a recording amplifier, 19 is a rotary transformer, 2O is a recording amplifier, 22 is a reproducing amplifier, 23a
, 23b are bandpass filters, 24a and 24b are detectors, 25 is a subtracter, 26 is an inverting amplifier, 27 and 28 are switch circuits, and 29 is a hold circuit. - Agent Masu Oiwa Figure 1 Figure 2 Figure 3 δa Soa bo SoD Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] (1) The head width of the magnetic heads is smaller than the track pitch, and includes a first set of rotating magnetic heads for recording recording signals and a second set of rotating magnetic heads for recording pilot signals. Tracks recorded by the first set of rotating magnetic heads and pilot signal tracks recorded by the second set of rotating magnetic heads are alternately formed on the magnetic tape. do,
Magnetic recording and reproducing device. (2) The magnetic recording and reproducing apparatus according to claim '1, characterized in that the two pylons 1 to signals are used and are switched and recorded every two signal tracks of the pylon 1 to each other. . (3) During reproduction, tracking servo is performed using the pilot signal included in the signal reproduced by the first set of rotating magnetic heads. The magnetic recording and reproducing device described in . (4) The second set of rotating magnetic heads is used to perform still image reproduction and slow reproduction. Device.