JPH02203456A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To omit the extreme accuracy required for the attachment positions of the leading and follower heads by storing the tracking states of the follower head and a track set at reproduction in a memory circuit and adding the tracking state of the follower head to control the leading head at after-recording. CONSTITUTION:In a normal reproduction mode, a 1st pair of heads 2a and 2b trace the center of a track, and the positions of a 2nd pair of heads 3a and 3b set to the track are stored in a memory circuit 16. In an after-recording state, the output of the circuit 16 is added to the output of a sample holding circuit 19 via an adder 14. At the same time, a control loop functions to set the output of the adder 14 at zero. Therefore the output of the circuit 19 is shifted by an extent equal to the voltage produced in the direction opposite to the output signal of the circuit 16 and then stabilized. Then the drive of the heads 2a and 2b are offset so that the heads 3a and 3b pass approximately the center of a track to be recorded. As a result, the track linearity is never deteriorated even though the head attachment accuracy is rather inferior.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing apparatus equipped with a magnetic head position correction function used in digital audio tape recorders, video tape recorders, and the like.

2. Description of the Related Art Conventionally, in a digital audio tape recorder that performs recording and reproduction using a rotating head, a signal (for detecting the positional relationship between the head and the recorded track) is placed at a predetermined location on a track formed on a magnetic tape. A method is used in which a tracking detection signal (referred to as a tracking detection signal) is recorded and the tracking detection signal is used during playback to control the head so that it runs correctly on the track. (for example,
(Japanese Patent Application No. 62-9304) An example of the above-mentioned conventional magnetic recording/reproducing device will be described below with reference to the drawings.

Figure 2 shows an example of a magnetic tape on which tracking detection signals are recorded, and Figure 6 shows tracking using the conventional magnetic tape shown in Figure 2 (the head runs correctly on the recorded track). A configuration diagram showing an example of a device (the control to perform tracking is called “tracking”), No. 7
This figure shows the relationship between the tracks on the magnetic tape shown in FIG. 2 and the head locus.

In the example in Figure 7, the tracking detection signal is a pilot signal (hatched area in Figure 31 and 32) that detects the degree of overlap between the head and adjacent tracks from crosstalk, and a synchronization signal (hatched area in Figure 7) that synchronizes the detection. Figure 33.33
a, 34 hatched areas).

In Fig. 6, 1 is a magnetic tape, 2a and 2b are a pair of heads that record and reproduce tracks in sequence with each other, 3a + 3b are a pair of heads that are attached to a position that records and reproduces with a time delay from the bare heads 2a * 2b, and 4 is a head. 2a*
2b+ 3a* 3b is attached to the rotating cylinder, 101 is the head 2am 2b+ 3at a
102 is a rectifier; 13 is a bandpass filter that filters a pilot signal for tracking from the output of
18 is a synchronization signal detection circuit that detects a synchronization signal for detecting a pilot signal from the outputs of the heads 2a+2b+3a, 3b, and 18 is a pulse SPI immediately after the synchronization signal detection circuit 13 detects the synchronization signal, and a pulse SP2 after a certain period of time.
15 is a pulse generation circuit that outputs a pulse S
A sample and hold circuit samples and holds the output of the rectifier 102 at the timing of PI, a subtractor 17 takes the difference between the output of the sample and hold circuit 15 and the output signal of the rectifier 102, and 19 samples the output of the subtracter at the timing of the pulse SP2. Sample hold circuit to hold, 9a
j 9b is a reel on which the magnetic tape 1 is wound, 8at
8b is a post forming a running path for the magnetic tape 1; 5a;
y5b is a capstan motor and capstan shaft for running the magnetic tape 1, 6 is a pinch roller,
7 is an FG that outputs a signal with a frequency proportional to the rotation speed of the capstan motor 5a; 10 is an F/v converter; 11
is an adder that adds the output of the sample hold circuit 19 and the output of the F/V converter 10, and 12 is the output of the adder 1.
This is a drive circuit that drives the capstan motor 5a based on force.

Same figure Nioite, FG7t F/V core/<-9109
The drive circuit 12 rotates the capstan motor 5a at a substantially constant rotation. The pinch roller 6 and the capstan shaft 5b apply the rotational force of the capstan motor 5a, which rotates at a constant rotation, to the magnetic tape 1, causing it to run at a nearly constant speed.

Next, a method for performing tracking in this conventional example will be explained.

In FIG. 2, 21 is a track, 22al 22b
is the recording position of the tracking detection signal, 23 is a vector indicating the traveling direction of the head, and 24 is a vector indicating the traveling direction of the magnetic tape 1. Figure 7 shows 2 in Figure 2.
This is an enlarged view of one of the areas 2a and 22b. 31 and 32 are pilot signals in which signals of the same frequency with less azimuth loss are recorded, and those with the same diagonal lines are recorded by heads with the same azimuth angle. (In the case of the same figure, recording is performed using heads with two azimuth angles.) 33 and 34 are synchronization signals for detecting signals from adjacent tracks of the pilot signal. Recorded with an azimuth angle head.

The tracking detection signal consists of a pilot signal and a synchronization signal.

37 is the head gap of the preceding head pair and arrow 38
Go in the direction of. 35 is the helad gap of the trailing head pair, which moves in the direction of arrow 36. Leading head pair 2
In order to reliably detect the pilot signal, the head width of the al 2 b helad gap 37 is set wider than the track width.

Bandpass filter 101 selects a pilot signal,
Further, a synchronization signal detection circuit 13 detects a synchronization signal on the track. The pilot signal filtered by the bandpass filter 101 is rectified and detected by the rectifier circuit 102. The synchronization signal detection circuit can be configured with a bandpass filter and a comparator, or can be configured to digitally detect the reproduced signal frequency. For example, when the headgear and the knob pass through the position shown in FIG. The pulse generating circuit 18 generates a pulse SPI at the moment when the head detects a synchronization signal, and a pulse SP2 a certain time later, a total of two pulses. The first pulse SPI is supplied to the sample and hold circuit 15, and the second pulse SPI
P2 is supplied to a sample hold circuit 19. S.P.I.
is generated, the head gap 37 is reproducing the pilot signal of the adjacent track on the right side in the direction of travel, and the SF
3 is generated when the head gap 37 is reproducing the pilot signal of the adjacent track on the left side in the traveling direction.

Therefore, the sample and hold circuit 15 samples and holds the pilot signal amplitude voltage from the right truck in the traveling direction. Further, the subtracter 17 calculates the difference between the output of the sample hold circuit 15 and the output of the rectifier 102. science fiction
3, the head gap 37 is reproducing the pilot signal of the adjacent track on the left side in the traveling direction, and the sample and hold circuit 19 samples and holds the difference in the amplitude voltage of the pilot signal from both adjacent tracks.

Since the crosstalk signal from the adjacent track is proportional to the amount of head protrusion to the corresponding track, the sample hold circuit 19 calculates the difference in the amount of head protrusion from both adjacent tracks, that is, the position of the center of the track and the center of the spacing gap. A voltage proportional to the difference is held.

In the conventional example shown in FIG. 6, the relative position between the traveling position of the heads 2a+2b and the recorded track is detected as the output of the sample hold circuit 19, and added to the output of the F/V converter 10 via the adder 11. By controlling the output signal of the sample hold circuit 19 to zero, the capstan motor 5a is rotated so that the head 2a12b runs on the recorded track.

Problems to be Solved by the Invention In such conventional technology, when a pair of heads is used, one of which is used as a pre-reading head and the other is used as an after-recording head that records later, strict requirements are placed on head mounting accuracy. For example, if the head is installed so that the head gap position is as shown at 35 in Figure 7, when this head is used as an after-recording head, it will not match the already formed track and position. Tracks that are misaligned are formed, and the connections between the tracks before and after the after-recording are not properly connected, resulting in distorted images during VTR playback and skipping during DAT playback.For example, when rewriting only part of a track. In this case, the pattern becomes extremely shifted only in the rewritten portion, and a similar problem arises in that the same image and audio problems occur during playback.

Therefore, in order to solve such problems, there has been a problem in that extremely high head mounting accuracy is required.

The present invention has been made in view of the above problems, and when two pairs of heads are used, one of which is used as a pre-reading head and the other as an after-recording head, even if the mounting accuracy of the heads is somewhat poor, the linearity of the track can be improved. The purpose of the present invention is to provide a magnetic recording and reproducing device that does not damage the magnetic field.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording/reproducing apparatus of the present invention provides a method in which a pilot signal and its detection synchronization signal for detecting a tracking position by crosstalk from adjacent tracks are recorded on a magnetic tape. At least two pairs of heads, a first head pair that precedes and temporally alternates recording and reproduction, and a second head pair that follows and temporally alternately records and reproduces, using a magnetic tape recorded on the formed track. a rotating cylinder to which a head pair is attached; a driving means for running the magnetic tape; a head pair discrimination circuit that outputs which of the two head pairs is currently being reproduced; and a filtering and rectifying circuit for filtering and rectifying the pilot signal from the output of the head pair. a pilot signal level detection circuit that detects the detected synchronization signal from the output of the head pair, a first pulse immediately after the synchronization signal detection circuit detects the synchronization signal, and a second pulse after a certain time. a pulse generator that outputs a total of two pulses, a first sample and hold circuit that samples and holds the output of the pilot signal level detection circuit using the first pulse, and the first sample and hold circuit. a subtracter that takes the voltage difference between the output of the pilot signal level detection circuit and the output of the pilot signal level detection circuit;
a first A that calculates the AND of the output signal indicating that the preceding head pair of the head pair discrimination circuit is reproducing and the second pulse;
an ND circuit, a second AND circuit that takes the logical product of the second pulse and an output signal indicating that the trailing head pair of the head pair distinguishing circuit is reproducing;
a second sample and hold circuit that samples and holds the output of the AND circuit; and a second sample and hold circuit that samples and holds the output of the AND circuit;
a third sample-and-hold circuit that samples and holds the output of the ND circuit; and a travel control circuit that controls the travel of the driving means using either the second sample-and-hold circuit or the third sample-and-hold circuit. and, when recording is not performed by the second pair of heads, the output of the second sample hold circuit or the third sample hold circuit that is not used by the travel control circuit is stored. and an adder that applies the output of the memory circuit to the output of the second sample and hold circuit when the first head pair is used to control travel and the second head pair is used to record. However, when the first head pair is used to control travel and the second head pair is used to perform recording, the apparatus is configured to output the output of the adder to the travel control circuit.

According to the above-described structure, the present invention controls the running of the magnetic tape using either the second sample hold circuit or the output of the third sample hold circuit to record the second sample when no after-recording is being performed. Among the outputs of the hold circuit or the third sample and hold circuit, the output of the side that is not used for travel control is stored in the storage circuit, and when recording is performed with the second pair of heads, the output of the side that is not used for travel control is stored in the second sample and hold circuit Travel is controlled by applying the output of the above-mentioned memory circuit to the output of the circuit.

In other words, one of the two head pairs controls tape running so that the head pair traces the track center, and the head and track information is determined from the playback signal of the head pair that is not used to detect the pilot signal. In addition to the control loop of the head pair that detects and stores the tracking voltage that indicates the position, and performs tracking to cancel that voltage during after-recording, the trace of the head pair that performs tracking is intentionally shifted, so that the recording head is at the desired track center position. Works to trace.

Embodiment Below, a magnetic recording and reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a magnetic recording and reproducing apparatus showing an embodiment of the present invention, FIG. 2 is an example of a magnetic tape on which tracking signals described in the conventional example are recorded, and FIG. 3 is a recording of tracking signals. FIG. 4 is an operation waveform diagram of the embodiment of FIG. 1, and FIG. 6 is a diagram showing an example of the structure of the memory circuit in FIG. 1.

Note that components having the same configuration and operation as the conventional example are given the same numbers.

In the example in Figure 3, the tracking detection signal includes a pilot signal (hatched areas in Figure 31 and 32) that detects the degree of overlap between the head and adjacent tracks from crosstalk, and a synchronization signal (hatched areas in Figure 31 and 32) that synchronizes the detection. Figure 33.34
It consists of a hatched area).

In FIG. 1, 1 is a magnetic tape, 2 al 2 b is a first head pair that sequentially records and reproduces tracks from each other,
3a and 3b are the second head pair 2 at 2 b, which are attached to the recording/reproducing position with a time delay from the first head pair 2 at 2 b.
head pair, 4 is head 2as2b.

A rotary cylinder 3a and 3b are attached, and 110 is a first head pair 2 al generated from a PG pulse generated in synchronization with the rotation of the rotary cylinder and a reference signal for its rotational phase control (both not shown). 2 be
Head pair discrimination circuit 101 that outputs a signal indicating which of the second head pairs 3 al' 3 b is currently playing back;
102 is a rectifier; 13 is a head 2; 102 is a rectifier; 13 is a head 2
a synchronization signal detection circuit for detecting a synchronization signal for detecting a pilot signal from the outputs of a, 2b, 3a, and 3b; 18;
15 is a pulse generation circuit that outputs two pulses: pulse SPI immediately after the synchronization signal detection circuit 13 detects a synchronization signal and pulse SP2 after a certain period of time, and sample hold 15 that samples and holds the output of the rectifier 102 at the timing of pulse SP1. Nagiji, 17 is sample hold circuit 15
a subtractor 1 that takes the difference between the output of the rectifier 102 and the output signal of the rectifier 102;
05 is an AND circuit that takes the logical product of the output of the head pair discrimination circuit 110 and the SP2 output of the pulse generator 18, and 19 is an A
A sample and hold circuit samples and holds the output of the subtracter 17 at the timing of the pulse SP2 that has passed through the ND circuit 105, 103 is an inverter that takes the logical inversion of the output of the head pair discrimination circuit 110, and 104 is the inverter 1
AND of the output of the head pair discrimination circuit 110 whose logic was inverted in step 03 and the SP2 output of the pulse generator 18.
circuit, 108 is the pulse SP that has passed through the AND circuit 104
A sample hold circuit samples and holds the output of the subtracter 17 at timing 2, a controller 107 instructs whether or not to perform after recording, and 1θ an AND circuit that outputs the output of the sample hold circuit 108 when the controller 107 does not instruct after recording. 1
04 is a memory circuit that stores information, and 106 is a memory circuit 16.
A switch 14 is used to select whether or not to transmit the output of the memory circuit 1θ according to a command from the controller 107, and 14 is a sample and hold circuit 1 for transmitting the output of the memory circuit 1θ via the switch 106.
9a+9b are reels on which the magnetic tape 1 is wound, 8a and 8b are bosses forming the running path of the magnetic tape 1), 5a+5b are for running the magnetic tape 1, respectively. 10 is an F/V converter, 11 is the output of the adder 14 and F An adder 12 that adds the outputs of the /V converter 10 is a drive circuit that drives the capstan motor 5a based on the output of the adder 1.1.

Next, the operation of this embodiment will be explained.

In the same figure, ite, FG7. F/V: 17/(-Jio.

The drive circuit 12 rotates the capstan motor 5a at a substantially constant rotation. The pinch roller 6 and the capstan shaft 5b apply the rotational force of the capstan motor 5a, which rotates at a constant rotation, to the magnetic tape 1, causing it to run at a nearly constant speed.

In FIG. 2, 21 is a truck, 22 al 22
b is the recording position of the tracking detection signal; 23 is a vector indicating the direction of movement of the head; and 24 is a vector indicating the direction of movement of the magnetic tape 1. Figure 3 shows 2 in Figure 2.
This is an enlarged view of one of the areas 2a and 22b. 31 and 32 are pilot signals, and signals of the same frequency with less azimuth loss are recorded, and those with the same diagonal lines are recorded by heads with the same azimuth angle. (
In the case shown in the figure, recording is performed using heads with two azimuth angles. ) 33 and 34 are synchronization signals for detecting signals from adjacent tracks of the pilot signal, and those with the same diagonal lines are recorded by heads with the same azimuth angle.

The tracking detection signal consists of a pilot signal and a synchronization signal.

37 is the head gap of the preceding head pair and arrow 38
Go in the direction of. 35 is the helad gap of the trailing head pair, which moves in the direction of arrow 3B. Leading head pair 2a
, 2b, the head width is set wider than the track width in order to reliably detect the pilot signal.

The head pair discrimination circuit 110 outputs the signal shown in FIG. 4A. In this signal, the high level is the first head pair 2a.
+2b either, low level is second head pair 3
(A in FIG. 4 shows a signal corresponding to one revolution of the rotary cylinder 4 for reference).

A bandpass filter 101 selectively filters the pilot signal, and a synchronization signal detection circuit 13 detects a synchronization signal on the track. The pilot signal filtered by the bandpass filter 101 is rectified and detected by the rectifier circuit 102. The synchronization signal detection circuit 13 can be configured with a bandpass filter and a comparator, or can be configured to digitally detect the reproduced signal frequency. Pulse generation circuit 18
pulse SP1 at the moment the head detects the synchronization signal,
After a certain period of time, the pulse SP2 is generated twice in total. On a magnetic tape with tracking detection signals recorded at two locations on each track as shown in Figure 2, the pulse SPI
, Pulse SP2 generates two pulses per trace for each head. Therefore, in the embodiment shown in FIG. 1 in which four heads are attached, eight pulses SP2 are generated per one revolution of the rotating cylinder 4, as shown in FIG.

Among these pulses, the AND circuit 106 selects and passes only those during the high level period of the output of the head distinguishing circuit, that is, those during reproduction of the first pair of heads 2a and 2b (FIG. 4). Also, in the AND circuit 104, the inverter 103
, the low level output of the head pair discrimination circuit 110, that is, the second head pair 3a, 3b
Only those that are being regenerated are selected and passed (Figure 4).

The sample hold circuit 15 connects the rectifier 10 with the pulse SP1.
Sample and hold the output of 2. In FIG. 3, when the head gap 37 advances as shown in the figure, when the synchronization signal detection circuit 13 detects the synchronization signal, that is, the pulse S
When P1 is generated, the head gap 37 is reproducing the crosstalk of the pilot signal of the adjacent tiger/vine on the right side in the direction of travel, and the pulse SP2 generated after a certain period of time is generated when the head gap 37 is in the direction of travel. It is generated in conjunction with the reproduction of the crosstalk portion of the pilot signal of the adjacent track on the left.

Therefore, the sample and hold circuit 15 samples and holds the pilot signal amplitude voltage from the right truck in the traveling direction. Further, the subtracter 17 calculates the difference between the output of the sample and hold circuit 15 and the output of the rectifier 102. When the pulse SP2 is generated, the head gap 37 is reproducing the pilot signal of the adjacent track on the left side in the traveling direction, and the AND circuit 105. When the pulse SP2 corresponding to the reproduction of the first head pair 2a, 2b gated with
2b is equal to the difference in pilot signal amplitude voltage from both adjacent tracks when it is being reproduced. Furthermore, when SF3 corresponding to the reproduction of the second head pair 3 al 3 b gated by the AND circuit 104 is generated, the output of the subtracter 17 is Equal to the difference in pilot signal amplitude voltage from adjacent tracks.

Therefore, the first head pair 2 is placed in the sample hold 19.
The difference in pilot signal amplitude voltage from both adjacent tracks when at 2 b is reproducing, and the difference in pilot signal amplitude voltage from both adjacent tracks when the second head pair 3a, 3b is reproducing is stored in the sample hold 108. Each difference in signal amplitude voltage is sampled and held.

Since the crosstalk signal from the adjacent track is proportional to the amount of head protrusion to the corresponding track, the sample and hold circuits 19 and 108 output the first head pair 2a+2b1 and the second head pair 3al, respectively.
A voltage proportional to the difference in the amount of protrusion of 3b to both adjacent tracks, that is, the difference in position between the center of the track and the center of the spacing gap, is held.

The controller 107 is composed of a microcomputer or the like, and instructs whether to perform after-recording or normal playback. First, the operation during normal playback will be explained.

During normal playback, the controller 107 outputs a low level. At this time, the memory circuit 16 stores the output of the sample and hold circuit 108 in accordance with the pulse SP2, and
Switch 106 is turned off to prevent signal transmission. In this case, the relative position between the traveling position of the first head pair 2a, 21) and the recorded track is detected as the output of the sample hold circuit 19 and added to the output of the F/V converter 10 via the adder 11. , by controlling the output signal of this sample and hold circuit 19 to zero, the first head pair 2a.

The capstan motor 5a is rotated so that the capstan motor 5a runs in the center of the recorded track.

In normal playback mode (not after recording),
The first head pair 2a, whose position is controlled via the sample and hold circuit 19, traces the center of the track. Further, the position of the second head pair 3a*3b with respect to the track is detected by the sample hold circuit 108 and stored in the storage circuit 16.

Therefore, in normal playback mode, the first head pair 2a
s2b traces the center of the track, and the position of the second head pair 3a+3b with respect to the track is stored in the storage circuit 16.

Next, a case will be described in which the controller 107 changes from the normal playback mode to the after-recording state.

In after-recording, the first head pair 2 at 2 b that precedes is reproduced, while the second head pair 3 at a b that follows records.

In response to entering the after-recording state, the storage circuit 16 stops updating data, and the switch 106 is switched to transmit the output of the storage circuit 16 to the adder 14.

In the embodiment of FIG. 1, the output of the storage circuit 1e is output to the adder
is added to the output of the sample hold circuit 19 via
Further, the control loop operates so that the output of the adder 14 becomes zero. Therefore, the output of the sample and hold circuit 19 is shifted by the same value to the voltage in the opposite direction to the output signal of the memory circuit 16, and becomes stable. In other words, the first head pair 2
a, 2'b are controlled so that the second head pair 3a, 3b is forcibly shifted in the opposite direction to the track center in the normal reproduction mode.

As a result, the first head pair 2a+3b passes through approximately the center of the track to be recorded.
+2b travel is offset.

This situation is shown using FIG. 37 represents the head gap of either the preceding first head pair 2a, 2b, and 35 represents the following second head pair 3a, 3.
b represents either helad gap.

Since the output of the memory circuit 16 is applied to the control loop of the first pair of heads 2a, 2b via the adder 14, the gap between the preceding pair of first heads 2at2b is shifted from the center of the track. , the locus of the second head pair 3at3b that follows comes to overlap with the track. In this FIG. 3, the preceding first head pair 2
An example is shown in which the head width of at2b is made wider than the track width, and the head width of the second pair of heads 3a and 3b that follows is made almost equal to the track width.

Furthermore, a first head pair 2a, 2b for tracking
The same bandpass filter 101 . Using the rectifier 1102, the memory circuit 1 stores the relative position of the second head pair 3a+3b and the track.
6 is stored, it is possible to accurately correct the head position without variations between circuits.

As described above, the deviation of the head from the track during after-recording, which was a problem in the conventional example, is resolved.

Next, a configuration example of the memory circuit 16 used in the embodiment shown in FIG. 1 will be described.

FIG. 5 shows an example of a memory circuit applied to the embodiment of FIG. In the figure, the part surrounded by a broken line is the memory circuit 16,
The other parts are the same as in FIG. 1 and are given the same numbers.

The output signal voltage of the sample and hold circuit 19 is converted into a digital value by an A/'D converter 161.

The controller 107 outputs a low level voltage during normal reproduction, and a high level voltage during after recording, and the inverter 164 inverts the signal and outputs it. AND
Since the circuit 165 takes the logical product of its output and the output signal of the AND circuit 104, the AND circuit 165 performs the AND circuit 1 only when the controller 107 outputs a low level.
04 is passed through.

That is, only during normal reproduction, the AND circuit 165 outputs the pulse SP2.
Output.

This SF3 causes the second head pair 3a.

3b and the track are digitized by an A/D converter 161 and stored in a memory circuit 162. D/A converter 163 is memory circuit 1
62 is converted into an analog voltage. That is, the storage circuit 16 stores and outputs a signal indicating the relative position of the head and track for replaying the second head pair 3a, 3b.

When the controller 107 sets the output to high level and instructs after-recording, the AND circuit 165 cuts off the sample pulse and the memory circuit 162 no longer stores the output signal from the A/D converter 161.
A voltage indicating the relative position of the second head pair 3 at 3 b and the track during normal reproduction is held. During this after-recording, the voltage indicating the relative position of the second head pair 3 at 3 b during normal playback and the track is applied to the first head pair 2 through the switch 10B.
a12b, and as a result, the running of the magnetic tape is controlled so that the running of the first head pair 2a+2b is offset so that the second head pair 3 at 3 b passes approximately through the center of the track to be recorded. be done.

Therefore, the operation as explained in the embodiment of FIG. 1 is ensured, and the deviation of the head from the track during after-recording, which was a problem in the conventional example, is eliminated.

Note that although the above explanation has been given using an example of a digital memory, it can also be realized using an analog sample-and-hold circuit that can obtain sufficient hold characteristics.

In addition, in the description of the embodiments shown in FIGS. 1 and 5, during normal playback,
We have shown an example in which the leading head pair controls the running of the magnetic tape and the trailing head pair detects the positional error between the track and the head pair, but conversely, the trailing head pair controls the magnetic tape running and the leading head pair It goes without saying that the same effect can be obtained by detecting the positional error between the track and the head pair.

Effects of the Invention As described above, according to this embodiment, when performing after-recording using two pairs of heads, the leading head performs tracking control during normal playback, and the tracking state of the trailing head and track at that time is stored in the storage circuit. By storing this information and controlling the leading head by adding the tracking state of the trailing head during after-recording, the writing position of the trailing head can be controlled to a desired position.

This eliminates the need for extreme precision in the mounting positions of the leading and trailing heads, significantly improving productivity.
Extremely large effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention, Fig. 2, Fig. 3
The figure shows an example of a recorded magnetic tape.
5 is a diagram of a configuration example of a storage circuit in the embodiment of FIG. 1, FIG. 6 is a configuration diagram of a conventional example,
FIG. 7 is a diagram of an example of recording on a magnetic tape used in a conventional example. DESCRIPTION OF SYMBOLS 1...Magnetic tape, 2a+2b...1st head pair, 3a, 3b...2nd head pair, 4.
... Rotating cylinder, 5a... Capstan motor, 6b... Capstan, 6... Pinch roller, 110... Head pair discrimination circuit, 101...
Bandpass filter, 102... Rectifier, 1
3... Synchronous signal detection circuit, 18... Pulse generator, 15゜19.108... Sample hold circuit,
17...Subtractor, 106...First AND
Circuit, 104...Second AND circuit, 7...F
G. 10... F/V converter, 11-... Adder,
12...Drive circuit, 1e...Storage circuit, 14.
106...Adder. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A device for recording and reproducing a magnetic tape in which a pilot signal for detecting a tracking position by crosstalk from an adjacent track and its detection synchronization signal are recorded on a track formed on the magnetic tape. a rotary cylinder to which at least two head pairs are attached, a first pair of heads that performs recording and reproduction alternately in time and a second pair of heads that follows and perform recording and reproduction alternately in time;
a drive means for running the magnetic tape; a head pair discrimination circuit for outputting which of the two head pairs is currently playing; a pilot signal level detection circuit for filtering and rectifying the pilot signal from the output of the head pair; and an output of the head pair. a synchronization signal detection circuit that detects the detected synchronization signal from a first pulse immediately after the synchronization signal detection circuit detects the synchronization signal; and a second pulse after a certain period of time;
a pulse generator that outputs a total of two pulses; a first sample and hold circuit that samples and holds the output of the pilot signal level detection circuit using the first pulse; and an output of the first sample and hold circuit. and the output of the pilot signal level detection circuit, and a first AND circuit that takes the logical product of the output signal indicating that the preceding head pair of the head pair discrimination circuit is reproducing and the second pulse. , a second AND circuit that takes the logical product of the second pulse and an output signal indicating that the trailing head pair of the head pair discriminating circuit is playing; and a second AND circuit that samples the output of the subtracter with the output of the first AND circuit. a second sample-and-hold circuit that holds the output of the subtracter; a third sample-and-hold circuit that samples and holds the output of the subtracter using the output of the second AND circuit; and the second sample-and-hold circuit or the third sample-and-hold circuit. a travel control circuit that controls the travel of the driving means using either of the outputs of the circuit; and an output of the second sample hold circuit or the third sample hold circuit when recording is not performed by the second pair of heads; a storage circuit for storing the output of the side whose output is not used in the travel control circuit; and a memory circuit for storing the output of the side whose output is not used in the travel control circuit;
an adder that applies the output of the storage circuit to the output of the sample-and-hold circuit of the adder; A magnetic recording/reproducing device characterized in that it is configured to output to the traveling control circuit.