JPH0359839A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To make a narrow track and to promote recording density by providing a detecting means for detecting a bend of a track based on a pilot signal regenerated by a regenerating means and a tracking control means for performing a tracking control based on the bend of the track detected by the detecting means. CONSTITUTION:As for a regenerative signal sent to a pilot signal detecting circuit 23, a low frequency pilot signal f1 in the regenerative signal is detected by the pilot signal detecting circuit 23 to generate a gate pulse. A signal level of a pilot signal f2 to be regenerated at cross talk from front and rear tracks is detected by this gate pulse, and the detected pilot signal f2 is compared by an error signal generating circuit 24 to generate a tracking error signal. Then, a servo control is carried out by a servo circuit 26 based on this tracking error signal. By this method, the narrow track formation is feasible, and hence the recording density can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a 6N recording and reproducing apparatus for recording and reproducing information signals such as video and audio using a rotating head.

[Prior Art] Conventional magnetic recording and reproducing devices use, for example, a pilot signal recorded in a predetermined area on a magnetic tape, a superimposed low-frequency pilot signal, or a head using a bimorph element or the like. The rotary head was tracked by vibrating a movable element and detecting the track position from the detected fluctuations in the reproduction envelope.

[Problems to be solved by the invention] However, in the conventional method described above, the following (1) to (3)
), and it was not possible to improve the recording density.

(1) In the so-called area-divided pilot system used in DAT, a portion of the tape is dedicated to pilot signals, which increases redundancy and makes it impossible to detect track bends.

(2) In the frequency superimposition pilot system used in 8mm VTRs, it is difficult to obtain a sufficient S/N ratio of the pilot signal, and when an extra low frequency signal is superimposed on a digital information signal, the error rate worsens.

As a method for preventing deterioration of the error rate, there is a method of suppressing low frequency components and separating them using a filter, but this requires a modulation method with high redundancy such as FM modulation or 8-1O conversion.

(3) In the so-called dither method in which the head is vibrated, the average output decreases due to envelope fluctuations, and waveform distortion and jitter occur in the reproduced signal due to amplitude fluctuations.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording/reproducing device that can solve the above-mentioned problems and improve recording density by narrowing the tracks.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a method for recording a pilot signal on one track at all according to a predetermined rule by helically scanning a rotary head on a strip-shaped record carrier. Alternatively, a recording means for recording at a plurality of predetermined locations or one predetermined location for one track, and a reproducing means for reproducing the pilot signal recorded on the record carrier by the recording means by helically scanning a rotary head. , a detecting means for detecting track bending based on the pilot signal reproduced by the reproducing means, and a tracking control means for performing tracking control based on the track bending detected by the detecting means.

[Function] According to the magnetic recording/reproducing device of the present invention, the recording density can be improved by narrowing the tracks.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the invention. This is digital V
This is an example of TR.

REC is a recording unit, which includes an A/D converter 11, a compression circuit 12,
buffer memory 13, modulation circuit 14, recording amplifier 15,
It is composed of a pilot signal generation circuit 16, an RFC/PR changeover switch 17, and a rotary head 2. 1 is a tape. PB is a playback section, which includes a rotating head 2,
llEC/PB selector switch 17, playback amplifier 18
, demodulation circuit 19, expansion circuit 20, D/A converter 21, pilot signal detection circuit 23, error signal generation circuit 24,
It is composed of a memory 25 and a servo circuit 26.

Next, the operation during recording will be explained.

The human input signal applied to the input terminal lO is input to the A/D converter 1.
1, the data is A/D converted by the compression circuit 12, compression processing and correction code addition processing are performed, and the data is stored in the buffer memory 13. The stored data is read out according to established rules and subjected to low frequency suppression modulation and I by the modulation circuit 14.
D addition etc. are performed, and the recording amplifier 15 amplifies the signal.
The information is recorded on the tape 1 by the rotating head 2.

The fixed rules for reading data from the buffer memory 13 include rearranging the data as a countermeasure against burst errors, that is, so-called shuffling, and inserting a pilot signal, which is a feature of the track pattern of the present invention. be. That is, data reading is stopped at the timing of the pilot area, and the pilot signal from the pilot signal generation circuit 16 is recorded. 1
Recorded at a rate of 2 tracks 1 frame, track 11
~TI2 is one frame, and tracks TI3 to T24 are the next one frame, and the pilot area setting and frame period are the same, making control easier. Furthermore, the aforementioned n is selected to be 360, so that a track with a different intrusion pattern of the pilot area appears once every 30 frames.

In this case, when recording is performed by scanning the rotary head 2 in the direction of arrow 4 while running the magnetic tape in the direction of arrow 3 in FIG. 2, recording is performed on track T1. T2. Tracks are formed in this order. At this time, truck T,
-T, each have four pilot areas, trucks T4-TI2 have no pilot area, trucks T13-Tn each have one pilot area, and truck T. +l+Tn+
Four pilot areas will be set up again at 2+Tn and 3. That is, with tracks T and ~Tn as one cycle,
By repeating this process and recording sequentially,
The tape pattern shown in FIG. 2 is obtained.

At this time, tracks Tl~T3, 74~T I 2 +
The size of the effective area that can be used for recording information signals in one track is different between T I 3 and Tn, but if you average the areas of tracks T and T12, there is one pilot area per track. Truck T13
is equal to ~T. Therefore, the information that could not be recorded due to the increase in the pilot area when recording track Tl-73 can be stored in a memory and sequentially read out and recorded when recording tracks T4 to T12.

Next, the operation during playback will be explained.

The signal reproduced by the rotary head 2 is amplified by a reproduction amplifier 18 via a REC/PR changeover switch 17 and sent to a demodulation circuit 19 and a pilot signal detection circuit 23.

The reproduced signal sent to the demodulation circuit 19 has its waveform shaped by the demodulation circuit 19, and is sent as a digital signal to the expansion circuit 20. The expansion circuit 20 expands the data.
Error correction, modification, etc. are performed, and the signal is converted into an analog output signal by the D/A conversion circuit 21 and output.

On the other hand, in the reproduced signal sent to the pilot signal detection circuit 23, the pilot signal detection circuit 23 detects the low frequency pilot signal f1 in the reproduced signal and generates a gate pulse. With this gate pulse, the signal level of the pilot signal f2 reproduced as crosstalk from the previous and subsequent tracks is detected, and the detected pilot signal f2 is compared by the error signal generation circuit 24 to generate a tracking error signal. Then, servo control is performed by the servo circuit 26 based on this tracking error signal. In this embodiment, tape forwarding is controlled by a tracking error signal generated from the pilot area at the beginning of one track. This is because the pilot area at this position exists almost continuously, and like tracks 14 to TI2,
The tracking error signal must be held in the section where no pilot area exists, but this period can be made the shortest, and in this embodiment, it can be made the shortest at 3/4 of one frame, that is, 1740 seconds. .

On the other hand, when error signals are obtained from four locations on one track, for example when track T2 is reproduced, the four error signal levels are written into the memory 25 as digital values. Since the data written in the memory 25 corresponds to the track bending, the difference between the average value of these data and the error signal level corresponding to the pilot area at the beginning of the track is determined and used as the target level. and,
This target bell is compared with the error signal generated from the pilot area at the beginning of the track as described above to output a tracking error signal, and the tracking error signal is outputted over the entire track length based on the outputted tracking error signal. Tracking control is performed so that the maximum output can be obtained on average.

In this embodiment, the data written in the memory 25 is weighted averaged in the ratio 1:3:3:1 in order from the beginning of the track. This is because the first and last areas have tracks on only one side of the front and back, and track bends generally tend to be large at both ends, so it is better to focus on the error signal in the middle area. This is because it is easy to obtain a suitable output.

Of course, other calculation methods such as the root mean square are also possible, and the method is not limited to this, but as in this embodiment, division by 2n (here, l◆3
4341-8) and addition, the actual hardware configuration is simpler.

In this embodiment, an example of a rotating head has been described, but if a movable head using a bimorph element or the like is used, data stored in a memory may be used for driving the movable head. In this case, the data stored in the memory may be the sum of the error signals generated from the four pilot areas and the data stored in the memory at that time and used to drive the head. That is, since the error signal when the head is driven is obtained from the current data on the memory, it is sufficient to correct the data on the memory by the amount of this error signal. Of course, the tape feed servo can be performed as described above, but since track bending is handled by a movable head, the tape feed servo can be performed using only the error signal from the pilot area at the beginning of the track. can be done, and the configuration is simpler.

Another Embodiment FIG. 3 shows a tape pattern obtained according to an embodiment of the present invention. In the figure, the same reference numerals indicate the same parts as in FIG.

In this embodiment, tracks TI, T2, and T2 have four pilot areas. After T, there is no pilot area for tracks T4 to T, and tracks Tm+l+Tl11+2
+Tffi+3 has one pilot area, track T1. There is no pilot area again from n+4 to 72 m, and there are four pilot areas from track Tn+1, and the repeating pattern is one cycle with tracks T, -T.

Next, a case where m=6 and n=18 will be explained.

The number of pilot areas for tracks T1 to TI8 is as follows: track 7. ,72. Ding. Then, 4 locations each, tracks T7-T
9. There are 18 locations in total, 1 location each for TI3 to T15, and this number matches the number of tracks. In order to record one frame of data on nine tracks, the data may be read from the memory 13 so that two frames constitute one period. In this case, the pilot areas at the beginning of the tracks are tracks T1 to T3, tracks T7 to T9, and track T.
I3~T+5. Since the tracks appear at a constant cycle from T19 to T2°, there is no need to perform special sample and hold as described above, and the servo system becomes simpler. Further, since an error signal covering the entire length of the track can be obtained once for 18 tracks, track bending can be detected.

In one embodiment and other embodiments, an example in which a maximum of four pilot areas are provided in one track has been described, but the invention is not limited to this example. Any place is fine.

Further, although an example has been described in which the pilot frequencies are two frequencies f, , f, the error signal may be generated using any method as long as the pilot area is a short portion of the track.

In one embodiment and other embodiments, a gate pulse is generated with the pilot signal f1, and the crosstalk of the pilot signal f2 of the front track and the rear track is detected to obtain an error signal, so that the pilot signal is the pilot signal The pilot areas must be arranged in three consecutive tracks in the order of f2, pilot signal flx pilot signal f2, but the pilot areas do not necessarily have to be arranged in three consecutive tracks, and can be arranged in one track, two tracks, or four tracks. However, the number does not matter as long as it is possible to generate error signals.

Furthermore, the error signal generation method is not limited to the above embodiment, and may be a method in which there are parts where there are multiple pilot areas in the longitudinal direction of the track and parts where they are not, and where the pilot areas are switched based on a certain rule. Good.

Further, although an example of a digital VTR has been described, an analog VTR may be used as long as a delay means is used.

[Effects of the Invention] As explained above, according to the present invention, since the structure is configured as described above, the recording density can be further improved by narrowing the tracks.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 52 is a diagram showing an example of a tape pattern according to an embodiment of the present invention, and FIG. 3 is a diagram showing an example of a tape pattern according to another embodiment of the present invention. It is a diagram. DESCRIPTION OF SYMBOLS 1...Tape, 2...Head, 11.../D converter, 12...Compression circuit, 13...Buffer memory, 14...Modulation circuit, 15...Recording amplifier, 16... Pilot signal generation circuit, 17... REC/PB changeover switch, 18...
Regeneration amplifier, 19... Demodulation circuit, 20... Expansion circuit, 21... D/A converter, 23... Pilot signal detection circuit, 24... Error signal generation circuit, 25... Memory , 26... Servo circuit.

Claims (1)

[Claims] 1) Either the pilot signal is not recorded at all on one track by helically scanning the rotary head on the strip-shaped record carrier according to a predetermined rule, or the pilot signal is recorded at a plurality of predetermined locations or at a predetermined location on one track. recording means for recording at one location on the record carrier; reproducing means for reproducing the pilot signal recorded on the record carrier by the recording means by helically scanning a rotary head; track bending based on the pilot signal reproduced by the reproducing means; What is claimed is: 1. A magnetic recording and reproducing apparatus comprising: a detection means for detecting a track bend; and a tracking control means for performing tracking control based on track curvature detected by the detection means.