JPH01312759A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution without needing any pilot signal alike a 4-frequency pilot ATF system by using plural sets of head pairs with the same azimuth angles and a step difference so as to reproduce 2 fields or over at the same time and applying tracking so as to maximize the reproduced output for each field. CONSTITUTION:The 1st and 2nd heads (recording reproducing heads) 3A, 3B with a different azimuth angle are prepared and the 1st synchronizing pattern is recorded to first 2-track by using the 1st and 2nd heads and the 2nd synchronizing pattern is recorded to the succeeding 2-track by using the 1st and 2nd heads. In case of reproduction, the 3rd and 4th heads (tracking heads) 4A, 4B having a prescribed step difference such as 1 track pitch and different azimuth angle to those of the 1st and 2nd heads are prepared. Then the 1st and 3rd heads 3A, 4A are used as a couple of heads of the same azimuth angle and the 2nd and 4th heads 3B, 4B are used as a couple of heads of the same azimuth angle and the tracks for 2-field recorded by a couple of head pairs are reproduced at the same time.

Description

[Detailed description of the invention] The invention will be explained in the following order.

Δ Industrial application field B Overview of the invention C Prior art D Problem to be solved by the invention E Means for solving the problem (Fig. 1) F Effect G Embodiment G3 circuit configuration (Fig. 1) G2 Circuit Operation (Fig. 2) H Effects of the Invention A Industrial Field of Application This invention is directed to magnetic recording and reproducing devices, especially ATF PAs. Two or more fields are recorded alternately, and two or more fields are simultaneously reproduced using multiple pairs of heads with the same azimuth with steps so that two or more fields can be simultaneously traced at the same time, and the reproduction output for each field is generated. By applying tracking so that the
Unlike the F method, there is no need to use a pilot signal, the circuit configuration can be simplified, and it is compatible with digital magnetic recording and reproducing equipment that uses channel coding that has a power spectrum up to low frequencies that are not DC-free. Stable RF as there is no need to shake the head left and right while playing and apply tracking
This makes it possible to obtain a doubled signal and to simplify the circuit configuration.

C. Conventional technology Conventionally, as a system for automatically tracking, C.
An example of a device that does not use a TL head is a 4-frequency pilot ATF (Automatic
There is a Track Finding method. During recording, four pilot signals are frequency-multiplexed with the video signal by a rotating video head as control signals for the capstan phase servo, and during playback, these signals are used to apply the capstan phase servo. In other words, the frequency of the pilot signal among the outputs from the video head during playback is low at 100 to 160 kHz, so almost no azimuth loss occurs in the head, so l! A J-contact track pilot signal is also reproduced. Therefore, the playback level of the pilot signals of two adjacent tracks will be the same when the head is running in the middle of the track, but if the head is running off to one side, there will always be a level difference, so this level difference should be It detects this and controls the capstan motor so that the level difference is eliminated.

Another method is to detect the RF multiplied signal and perform tracking while swinging the head from side to side so that the signal is always maximized.

D. Problems to be Solved by the Invention However, in the case of the above-mentioned 4-frequency pilot 1-ATF method, it is necessary to use multiple pilot signals and to switch between them, which has the disadvantage that the overall configuration of the tracking servo system becomes complicated. there were. In addition, in a digital magnetic recording/reproducing device, for example, as shown in FIG.
Equipment that uses a channel coding system using recorded signals that are not fried cannot record pilot signals in the low frequency range, and at the same time cannot separate and reproduce the pilot signal buried in the low frequency range from the data during playback. In other words, the power spectrum extends to the low frequency range without DC fried. Digital magnetic recording and reproducing apparatuses using certain channel codings have drawbacks that cannot be addressed.

In addition, in the case of a method of detecting the RF multiplied signal and performing tracking so that it is always at its maximum, it is impossible to recognize whether the head is shifted to the right or to the left, especially in digital magnetic recording and reproducing devices, so the head must always be swung left and right. However, since it is necessary to detect the position of the just track and perform tracking, the RF multiplied signal is not stable and only an unstable reproduced signal can be obtained.

The present invention has been made in view of this problem, and an object thereof is to provide a magnetic recording/reproducing apparatus that can automatically perform tracking without using a pilot signal.

E. Means for Solving the Problems The magnetic recording and reproducing apparatus according to the present invention is a magnetic recording and reproducing apparatus in which a plurality of types of synchronization patterns are prepared, and the synchronization patterns are recorded alternately every two fields with the azimuth changed every field. This is a recording/reproducing device that uses a plurality of pairs of heads with the same azimuth (3^ and 4) with steps so that two or more fields can be traced simultaneously at the same time.
8, 3B, and 48), this head is used to simultaneously reproduce two or more fields, and tracking is applied so that the reproduction output for each field is maximized.

F During recording, for example, the first and second synchronization patterns are recorded alternately every two fields (two tracks) with the azimuth changed every field. That is, first and second heads (recording/reproducing heads) with different azimuths (3A, 3B
>, record the first synchronization pattern on the first two tracks with the first and second heads, and record the second synchronization pattern with the first and second heads on the next two tracks. . Also, during playback, in addition to the first and second heads, third and fourth heads (tracking heads) (4^ , 4B), the first and third heads (3A, 4^) are a pair of heads with the same azimuth, and the second and fourth heads (3B, 4B) are prepared.
are a pair of heads with the same azimuth (different azimuth from the above pair of heads), and these pairs of heads simultaneously reproduce two fields of tracks recorded as described above. Then, when tracking is achieved (just track), maximum playback output is obtained from the first and second heads for each field, and no tracking error signal is obtained from the third and fourth heads. . on the other hand,
When the tracking becomes misaligned, the first and second heads produce a decreasing reproduction output corresponding to the misalignment for each field, and the third and fourth heads produce outputs corresponding to the misalignment. A tracking error signal is obtained. If the tracking servo is applied based on this tracking error signal, accurate tracking can always be performed. In this way, there is no need to use a pilot signal for tracking as in the past, and tracking can be performed using a synchronization pattern added to the head of normal data, so the configuration is simple, and the head can be Since there is no need to swing from side to side, a stable playback signal can be obtained.

G. Example Hereinafter, an example of the present invention will be described in detail based on FIGS. 1 to 7.

G1 Circuit configuration Figure 1 shows the overall circuit configuration of this embodiment. In the figure, (1) is a rotating drum, and (2) is a circuit that is wound around the rotating drum (1) in a predetermined angle range. magnetic tape, (
3A) and (3B) are recording/reproducing heads provided facing the rotating drum (1), and these heads have different azimuth angles. Also (4A), (4
13) are tracking heads provided adjacent to the heads (3A) and (3B) and facing the rotating drum (1), which are the heads (4^) and (4B).
) have a predetermined step difference from the heads (3A) and DB), for example, one track pitch T1. Also, head (3A) and (4A) and head <3B)
B) have the same azimuth angle.

(5) is an input terminal to which an analog audio human input signal is supplied, and the audio human input signal from this input terminal (5) is converted into a digital signal by an A/D conversion circuit (6), and an error correction circuit ( 7), Memo IJ (
8) and (9) are used to perform signal processing such as error detection/correction, time axis compression, and parity addition. This signal-processed signal is subjected to predetermined modulation, for example, 8/1O conversion, in a modulation circuit (lO), and first and second synchronization patterns are added thereto as will be described later.

(11) is a head switching switch circuit provided on the output side of the modulation circuit (10), and includes an FG (frequency generator) and a PG (pulse generator) (not shown) attached to the drum (1). ) is switched by a switching pulse (SWP) formed based on a signal from the head (3B). For example, when recording with the head (3^), the head (3B)
When recording with , the contacts are switched to the B side. (12
), (13) are recording amplifiers, (14), (15
) is a switch circuit for recording/playback switching, and these switch circuits (14) and (15) are controlled by a switching signal from an external system controller (not shown). For example, in recording mode, contact R side , and are switched to the contact P side in the playback mode.

(16) and (17) are rotary transformers.

The recording system is configured in this way.

(18) and (19) are regenerative amplifiers, (20) is a switch circuit that operates in the same way as switch circuit (11), and (21)
) is an equalizer that performs reproduction equalization to remove code amount interference, and the output of this equalizer (21) is sent to a comparator (2
2) and is also supplied to the inverting input terminal of the comparator (22) via the DC regeneration circuit (23). A digital signal of "1" and "0" is obtained from the comparator (22).This digital signal is supplied to the input terminal of the D-type flip-flop circuit (24) and is doubled by the multiplier circuit (25). It is multiplied and the PLL circuit (
26), and the recovered clock is extracted from the PLL circuit (26) and supplied to the clock terminal C of the flip-flop circuit (24). Then, reproduced data is taken out from the output terminal Q of the flip-flop circuit (24), and is supplied to a reproduced data processing system (not shown) to restore the original signal. In this way, the reproduction system is configured.

(25) and (26) are respectively low retrans (27),
(28) via a tracking head (4^),
(4B) Tracking playback amplifier connected to
(29) is a switch circuit that is switched by a switching pulse like switch circuits (11) and (20), and the reproduced signal that has passed through this switch circuit (29) is supplied to a peak detector (30) for tracking. It is detected as an error signal and the sample hold circuit (31
) is sample held. The sampled and held tracking error signal is sent directly or to an inverter (32).
The signal is supplied to the switch circuit (33) via the switch circuit (33). This switch circuit (33) is used to shift the head to the right, as will be described later.
Switched according to left shift.

The tracking error signal that has passed through the switch circuit (33) is supplied as a phase servo signal to the negative input terminal of an adder (34), and is added to the speed servo signal from the speed servo circuit (35). Then, the output signal of the adder (34) is amplified by the motor drive circuit (36) and supplied to the capstan motor (37). (38) is an FC detector that detects speed servo information. In this way, a capstan servo system is constructed.

Furthermore, the reproduction signal that has passed through the switch circuit (29) is directly supplied to the comparator (40) via an equalizer (39) similar to the equalizer (21), and is further supplied to the DC reproduction circuit (40).
1) to the comparator (40).

The digital signal from the comparator (40) is sent to the PLL circuit (2
6) is taken into the D-type flip-flop circuit (42) in synchronization with the recovered clock, and is further supplied to the demodulation circuit (43) where it undergoes a predetermined demodulation, for example, NRZI demodulation, and is sent to the subsequent shift register (44). supplied to

The contents of the shift register (44) are transferred to the pattern comparator (45).
) and (46). Pattern comparator (45)
.

Patterns equivalent to the first and second synchronization patterns added by the modulation circuit (10) in advance are set in (46), respectively, and the first and second synchronization patterns, which are the contents and settings of the shift register (44), are set in advance. When the synchronization patterns match, output signals are obtained at the output sides of the pattern comparators (45) and (46), respectively. These output signals are the switch switching circuit (47)
The switch switching circuit (47) switches the switching circuit (28) depending on whether the supplied output signal is from either the pattern comparator (45) or (46). For example, the switch switching circuit (47) determines that the head is shifted to the right if the output signal is from the pattern comparator (45), switches the switch circuit (28) to the contact B side, and outputs the signal from the pattern comparator (46). If the output signal is , it is determined that the head is shifted to the left, and the switch circuit (28) is switched to the contact A side. In this way, the head shifts to the right,
A circuit system for detecting left shift is configured.

FIG. 2 shows an example of a specific circuit of the modulation circuit (10), in which serial data from the error correction circuit (7) (FIG. 1) is supplied to the shift register (10a) and the latch circuit (10b) is latched by R
For example, data conversion from 8 bits to 10 bits (8/10 conversion) is performed in the OM (10c), and the latch circuit (
10d) is latched to.

(10e) and (10f) are circuits that generate the first and second synchronization patterns, respectively, and are switch circuits (10e) and (10f).
0g) is switched every two fields, and the circuit (10
e).

The first and second synchronization patterns from (10f) are supplied to the parallel/serial conversion circuit (10i) via the switch circuit (10h). Subsequently, the data latched in the latch circuit (10d) is supplied to the parallel/serial conversion circuit (10i) via the switch circuit (loh).

The parallel/serial conversion circuit (10i> converts manually input parallel data into serial data, and then converts it into N
The RZI modulation circuit (10j) performs NRH modulation and outputs. Therefore, the output side of the modulation circuit (lO), that is, NR
On the output side of the ZI modulation circuit (LOI), there is a
PCM data to which first and second synchronization patterns are added alternately for each field is output.

Note that the first and second synchronization patterns are generally 2" in addition to the data code when considering m/n conversion, for example.
Since there are -2''' extra codes, any appropriate code can be selected as the synchronization pattern.

FIG. 3 shows an example of a specific circuit of the PLL circuit (26), in which (26a) is a phase comparator;
(26b) is a low-pass filter, (26C) is a voltage controlled oscillator, (26d) is a 1/N frequency divider,
With this configuration, it is a normal general PLL circuit.

In this case, there is no problem when the PCM data exists continuously, but when reproducing burst data, the error voltage applied to the oscillator (26C) becomes discontinuous, and the average value of this discontinuous voltage is equivalent to oscillator (26c
) oscillates, but since the error voltage is intermittent, it is less stable than when it is continuous.

Therefore, here, a sample and hold circuit (26) is connected between the low-pass filter (26b) and the oscillator (26c).
e) Insert the output of the low-pass filter (26b), that is, the oscillator (26C) during the period when data exists.
The error voltage, which is a human input to the oscillator (26c), is sampled and held to suppress fluctuations in the output of the low-pass filter (26b) and stabilize the oscillator (26c).

62 Circuit Operation Next, the operation of the circuit shown in FIG. 1 will be explained with reference to FIGS. 4 to 7.

The analog audio signal from the input terminal (5) is A/
It is converted into a digital signal by the D conversion circuit (6) and supplied to the error correction circuit (7), where it is sent to the memo IJ (8).

(9) is used to undergo signal processing such as detection correction, time axis compression, and addition of parity. This signal-processed signal is supplied to the modulation circuit (10), where it is subjected to predetermined modulation, for example, 8/10 conversion, and the first and second synchronization patterns are added alternately every two fields to the top of the signal as described above. be done.

In this way, the data to which the first and second synchronization patterns have been added passes through the switch circuit (11) and the recording amplifier (11).
2), (13) is amplified by the head (3^),
(3B). At this time, switch circuit (11)
is alternately switched between a half-rotation period, which is approximately the tape contact period of the head (3A), and a half-rotation period, which is approximately the tape contact period of the head (3B), by a switching pulse. Therefore, as shown in FIG. 4, the magnetic tape (2) has tracks TAI during the first rotation of the rotating drum (1).
One field of data to which the first synchronization pattern has been added is recorded by the rotating head (3A), and the data is recorded on the track TR.
One field of data with the first synchronization pattern added by the rotary head (3B) is recorded on track TA2 by the rotary head (3B), and in the next rotation, data with the second synchronization pattern added with the rotary head (3A) is recorded on track TA2. One field is recorded, and the second field is recorded on track TB□ by the rotating head (3B)
One field of data with the synchronization pattern added is recorded. In other words, the magnetic tape (2) has the first and second
The synchronization pattern is recorded alternately every two fields (two tracks) with the azimuth changed every one field (one track). Of course, data is recorded alternately with the azimuth changed every field (one track). In Fig. 4, + and - represent different azimuths, and 1,
2 represent the first and second synchronization patterns, respectively.

Each track shown in FIG. 4 consists of a large number of 1 synchronization blocks as shown in the upper part of FIG. 5, and the number of blocks is, for example, 132 for a 3 mm VTR and 144 for a ROAT.

For example, in the case of RDAT, each synchronization block consists of an 8-bit synchronization pattern, an ID code, a block address, a parity, and 256-bit PCM data, as shown in the lower part of FIG. The provided 8-bit synchronization pattern differs every two fields (two tracks).

Also, during playback, the signals played by the heads (3^) and (3B) are sent to the playback amplifiers (18) and (19), respectively.
The signal is amplified by a switch circuit (20) every half rotation of the rotating drum (1) and supplied to an equalizer (21). After the equalizer (21) performs reproduction equalization to remove the code amount interference, the comparator (22) converts it into a digital signal and supplies it to the flip-flow knob circuit (24).
Data synchronized with the reproduced clock extracted by the PLL circuit (26) is obtained on the output side, and is supplied to a reproduced data processing system (not shown).

In addition, the signals reproduced by the tracking head (4A) and (4B> are transmitted to the reproduction amplifiers (25) and (26), respectively.
The signal is amplified by a switch circuit (29) every half rotation of the rotating drum (1), and is supplied to a peak detector (30) and an equalizer (39).

The signal supplied to the peak detector (30) is peak detected here and taken out as a tracking error signal. Now, in FIG. 4, the magnetic tape (2) is transported in the direction of arrow T, and the heads (3A) and (4A) are moved in the direction of arrow H.
If the head is moving in the direction of , the head (3^
) and (4A) are, for example, just tracks TA2 and T[1
In the case of a so-called "just track" scanning above 2, if the azimuth angles of heads (3A) and (4A) are both +azimuth, (the azimuth angles of heads (3B) and (4B) are both 1 azimuth), then , tracking head (4
In A), since the track Ta2 with a different azimuth is scanned, no tracking error output is obtained on the output side of the peak detector (30), which is O as shown in FIG. Conversely, this means that the reproduction output of the recording and reproduction heads (three persons) is maximized.

However, when the tape (2) is fed quickly, the heads (3A) and (4^) shift to the right in the drawing, so the head (4A) scans the tracking TAI of the same azimuth on the right side. , peak detector (30)
As shown by the solid line in Fig. 6, a tracking error output is obtained on the output side of It reaches a maximum at the point where the track TA-2 of the same azimuth is dragged, and then decreases again depending on the amount of track deviation to the right.

On the other hand, if the tape (2) feed is slow, the head (
3A) and (4A) will shift to the left, so
Head (4A) is the same azimuth track T A on the left.
2, a tracking error output is obtained on the output side of the peak detector (30), which gradually increases in accordance with the amount of track deviation to the left, as shown by the solid line in Figure 6. The level is about 1 track pitch.
T, deviated location, that is, the track T with the same azimuth on the left
It reaches a maximum when just tracked to A2, and then decreases again depending on the amount of track deviation to the left.

The above is also true for heads (3B) and (4B>).In this way, a tracking error signal corresponding to the amount of track deviation of the head is obtained on the output side of the peak detector (30). The tracking error signal is supplied to the next stage sample and hold circuit (31), where it is sampled and held.

Now, as mentioned above, a tracking error output as shown by the solid line in FIG. 6 is obtained on the output side of the peak detector (30) depending on the head misalignment.
) is slow (shifting to the left), it is necessary to accelerate the capstan motor (37), so it is best to supply a positive tracking error signal as shown in Figure 6. ) is moving quickly (shifting to the right), the tracking error signal shown in Figure 6 has positive polarity even though it is necessary to decelerate the capstan motor (37), so this is shown by a broken line. It is necessary to invert the signal to have a negative polarity to produce a tracking error signal as shown in FIG.

Therefore, in this embodiment, if the output of the sample and hold circuit (31) is a tracking error signal due to left shift, it is passed through the switch circuit (33) as it is, and if it is a tracking signal due to right shift, it is inverted by the inverter (32) and sent to the switch circuit. (33). The switch circuit (33) is switched to the contact A side when the shift is to the left, and to the contact B side when the shift is to the right.

In this embodiment, the above-mentioned first
and a second synchronization signal. Next, a circuit related to this will be explained.

The reproduced signal that has passed through the switch circuit (29) is passed through the equalizer (
39) to the comparator (40), and is further supplied to the comparator (40) via the DC regeneration circuit (41). As a result, the output side of the comparator (40) has a digital signal. is obtained. This signal is taken into the flip-flop circuit (42) in synchronization with the regenerated clock from the PLL circuit (26), and is further supplied to the demodulation circuit (43) where it is subjected to NR21 demodulation and then shifted into the shift register (44).
).

The contents of the shift register (44) are transferred to the pattern comparator (45).
) and (46), and are compared with preset first and second synchronization patterns, respectively. When the contents of the shift register (44) match the first synchronization pattern, an output signal indicating that the head has shifted to the right is obtained from the pattern comparator (45), and the contents of the shift register (44) When the content matches the second synchronization pattern, an output signal is obtained from the pattern comparator (46) indicating that the head has shifted to the left.

This can be understood from Figure 4. That is, the tape (
2) When the feed speed becomes faster, the head (3A
) and (4A) are shifted to the right, so that the head (4A) scans the adjacent track TAI on the right with the same azimuth. And this truck TAI has the first
Since the first synchronization pattern is recorded, this first synchronization pattern is reproduced by the head (4A) and the shift register (
44) and is set in the pattern comparator (45), so as a result, the output side of the pattern comparator (45) indicates that the head has shifted to the right. An output signal will be obtained.

On the other hand, if the tape (2) is fed slowly, the heads (3A) and (4^) will shift to the left in the drawing as described above, so the head (4^) will move from track TA2 of the same azimuth to the left. It starts scanning. And this truck T
Since the second synchronization pattern is recorded in A2, this second synchronization pattern is reproduced by the head (4A), supplied to the shift register (44), and then sent to the pattern comparator (46).
As a result, an output signal indicating that the head has shifted to the left is obtained on the output side of the pattern comparator (46).

Each output signal from the pattern comparators (45) and (46) is supplied to a switch changeover circuit (47). When this switch switching circuit (47) is supplied with the output signal from the pattern comparator (45), it switches the switch circuit (33) l to the contact B side and transfers the tracking error signal of negative polarity to the adder (34). - Supply to the input end of the speed servo circuit (
35), and the added output drives the capstan motor (37) via the motor drive circuit (36), lowering its rotational speed and slowing down the feeding of the tape (2). ) accurately scans the track TAf. Further, when the switch switching circuit (47) is supplied with the output signal from the pattern comparator (46), it switches the switch circuit (33) to the contact A side and sends the positive tracking error signal to the adder (34). - The output of the speed servo circuit (35) is added to the output of the speed servo circuit (35), and the added output drives the capstan motor (37) via the motor drive circuit (36) to increase the rotational speed of the tape ( 2) Speed up the feed so that the head (3A) accurately scans the track TAi.

The same applies when scanning other tracks, and
The same function applies to heads (3B) and (4B).

In the above-described embodiment, the number of heads is four in total and the number of synchronization patterns is two, but it goes without saying that the present invention can be similarly applied to the case of more combinations.

Effects of the invention As described above, according to the invention, multiple types of synchronization patterns can be recorded alternately every two fields by changing the azimuth for each field, making it possible to simultaneously trace two or more fields at the same time. Two or more fields are simultaneously reproduced by using multiple sets of Heratra pairs of the same azimuth with steps, and tracking is applied so that the reproduction output for each field is maximized.
(Frequency Pilot) A pilot signal such as in the ATF system is not required, and the circuit configuration can be simplified. Furthermore, the present invention can also be applied to a digital magnetic recording and reproducing device that uses channel coding that is not DC-free and has a power spectrum down to the low frequency range. Furthermore, since there is no need to perform tracking by swinging the head left and right during playback as in the prior art, a stable RF multiplied signal can be obtained, stable operation can be guaranteed, and the circuit configuration can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, FIGS. 2 and 3 are circuit configuration diagrams each showing an example of the main part of the invention, and FIGS. 4 to 7 are operation diagrams of the invention. FIG. 8, which is a diagram for explanation, is a diagram showing a recording signal that is not DC-free. (2) is a magnetic tape, (3A) and (3B) are recording/reproducing heads, (4A) and (4B) are tracking heads, (6) is an A/D conversion circuit, and (7) is an error correction circuit. , (10) are modulation circuits, (12), (13
) are recording amplifiers, (18), (19). (25), (26) are regenerative amplifiers, (30) are peak detectors, (32) are inverters, (33) are switch circuits, (37) are capstan motors, (44) are shift registers, (45) , (46) is a pattern comparator, and (47) is a switch changeover circuit. Agent Price Page spacing
Matsukuma Hide Mori PLL Enshupu Futai Kaijocho Figure 3 Za-27χ-Taft Figure 5 Action Explanation Picture Figure 6 v1 Worked Figure 7 Accent Kanzu Speech S7 and Ram Figure 8

Claims (1)

[Claims] A plurality of types of synchronization patterns are prepared, and one of the synchronization patterns is
A magnetic recording/reproducing device that changes the azimuth for each field and records alternately every two fields, using a pair of heads with the same azimuth and a step so that two or more fields can be traced simultaneously at the same time. 1. A magnetic recording and reproducing apparatus characterized in that a plurality of sets of magnetic recording and reproducing heads are provided, two or more fields are simultaneously reproduced using the head, and tracking is applied so that the reproduction output for each field is maximized.