JPH0246561A - Magnetic tape reproducing device - Google Patents

Abstract

PURPOSE:To make a head trace accurately in the middle of a track and to improve playability by providing a subtractor for obtaining a difference between two sample circuits in their output signals to be a tracking error output. CONSTITUTION:The subject device possesses a switch circuit 1 capable of being turned on only during the time of reference pulse. The outputs of the heads 1a and 1b are inputted to a synchronizing signal detecting circuit 8, where two sample pulses in total are generated at the time of detecting a synchronous signal on a track by the synchronous signal detecting circuit 8 and after delaying it by a given period of time by a timing circuit 9. On the other hand, a tracking signal which is proportional to a crosstalk quantity with both adjacent tracks of the reproducing head is selectively detected out of the output signal of the heads 1a and 1b by a detection circuit 11. An output of this detection circuit 11 is sample-held by sample circuits 61 and 62 using the two sample pulses, and their difference is obtained by the subtractor 63 to be a tracking error signal (e). In such a manner, control amts. of plural tracking signals on one track are equalized, and the recorded track can be traced on average in the middle by the head.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic tape playback device that can be used in digital audio tape recorders, video tape recorders, and the like.

Conventional technology In a digital audio tape recorder that performs recording and playback using a rotating head, a signal (tracking detection signal) for detecting the positional relationship between the head and the recorded track is placed at a predetermined location on the track formed on the magnetic tape. A method is used in which the tracking detection signal is used to record a track (referred to as ``track''), and then use this tracking detection signal during playback to correctly move the head 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 signals for tracking detection are recorded, and Figure 5 shows tracking using the conventional magnetic tape shown in Figure 2 (the head runs correctly on the recorded track). Figure 6 is a diagram showing its operation timing, and Figure 7 shows the track and head trajectory on the magnetic tape shown in Figure 2. FIG.

In FIG. 5, 1a and 1b are heads, and 1 is head Ia.
, lb is attached, 2 is a magnetic tape, 3 is a capstan motor for running the magnetic tape 2, 4 is an FG that outputs a signal with a frequency proportional to the number of rotations of the capstan motor 3, 5 is a rotary cylinder capstan motor 3
8 is a sync signal detection circuit that detects a sync signal to detect a tracking detection signal and outputs a pulse; 9 is a sync signal detection circuit that detects a tracking detection signal for a certain period of time from the output pulse of the sync signal detection circuit 8; 11 is a detection circuit that detects the tracking detection signal; 61 and 62 are sample circuits that sample the output signal of the detection circuit 11 using the output pulses of the synchronization signal detection circuit 8 and the timing circuit 9; 63 is sample circuit 8
1.62 is a subtracter that takes the difference between the output signals, 6 is a subtracter 63
7 is a drive circuit that drives the capstan motor 3 based on the output of the adder 6.

In addition, in FIGS. 2 and 7, 21 is a truck;
A is the center line of the track, 21B is the center point of the track, 2
2a122b is the recording position of the tracking signal, 23 is the head trajectory, and 23A is the center line of the head trajectory.

The operation of the magnetic recording/reproducing apparatus configured as described above will be described below with reference to FIGS. 5 and 6.

First, in FIG. 5, the rotary cylinder 1 has a head la.
, 1b are attached and rotate at high speed so that the heads 1a and 1b trace the tracks on the magnetic tape 2. The outputs of the heads la and lb are sent to the synchronization signal detection circuit 8.
Tora, entered into.

When the synchronization signal on the top is detected by the synchronization signal detection circuit 8,
Then, a total of two sample pulses are generated after a certain time delay in the timing circuit 9. On the other hand, among the output signals of the heads la and 1b, a tracking signal proportional to the amount of crosstalk with both adjacent tracks of the reproducing head is selectively detected by the detection circuit 11. The output of the detection circuit 11 is sampled and held by the sample circuits 61 and 82 using the two sample pulses mentioned above, and the difference is taken by the subtracter 63 to obtain the tracking error signal e (the signal is shown in FIG. 6e). The capstan motor 3 is an FG that outputs an output signal with a frequency proportional to the number of rotations.
4, speed control circuit 5, and drive circuit 7, the head 1 al lb
It works to enable the tracking of FIG. 2 shows an example of the position where the tracking signal is recorded in the shaded area 22a.
.

22b. In FIG. 5, a (the signal is shown in FIG. 6 a) is the head reproduction signal output, and b is the tracking signal detected by the detection circuit 11 (the signal waveform is shown in FIG. 6 b).

Similarly, C is a sample pulse output by the synchronization signal detection circuit 8, and the timing circuit 9 outputs a sample pulse d (signal waveforms are shown in FIGS. 6c and 6d). The subtracter 63 takes the difference between the sample pulse circuits 61 and 62, and the result is output as a tracking error output e. The device shown in FIG. 5 works so that this tracking error output e becomes zero,
As a result, the head 1a11b is controlled to pass through the center of the track 21.

In the operating waveform diagram shown in FIG. 6, in the tracking error output e at this time, section A is the tracking error output due to the tracking signal portion 22b of the output of the head 1a, and section B is the tracking error output of the tracking signal portion 2 of the output of the head 1a. '2a is the tracking error output. Similarly, section A1 is the tracking signal portion 2 of the head 1b output.
The section B1 is the tracking error output due to the tracking signal portion 22a of the head 1b output, and A: B = A1: B11.
: There is a relationship of 2. As shown in FIG. 7, due to the discrepancy in these periods, when the inclination of the track 21 on the magnetic tape 2 and the inclination of the head trajectory 23 are different, the control amount of the tracking signal 22a becomes larger than the control amount of the tracking signal 22b. Also, the center line 23A of the head trajectory 23 does not pass through the center point 21B of the track.

Problems to be Solved by the Invention In such conventional technology, section A, section B, and section A
There is a large difference in time between section B1 and section B1, and even if the tracking signal is on one track, there is a difference in the control amount, and the head does not trace the center of the track correctly, resulting in poor playability.
(The playability of a magnetic tape with a large deviation from the standard recording pattern is called "playability.")
This had the problem that it deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a magnetic recording/reproducing device that has a simple configuration and allows the head to accurately trace the center of the track to improve playability.

Means for Solving the Problems In order to solve the above problems, the present invention provides a system in which a tracking signal for detecting a tracking position by crosstalk from adjacent tracks and a synchronization signal for detecting the tracking signal are provided on a magnetic tape. A device for reproducing a magnetic tape recorded at a plurality of predetermined positions on formed tracks, the device comprising: a rotating cylinder to which a head is attached; a drive means for running the magnetic tape; a synchronous signal detection circuit for detecting a synchronous signal and outputting a pulse; a timing circuit for outputting a pulse after a certain period of time after the synchronous signal detection circuit detects the synchronous signal; and a timing circuit for obtaining the amplitude of the tracking signal. a detection circuit, and the output of the detection circuit is divided into two of the output pulse of the synchronization signal detection circuit and the output pulse of the timing circuit.
two sample circuits that each sample and hold with one pulse, a subtracter that takes the difference between the output signals of the two sample circuits and outputs the tracking error, and the tracking error output times of the plurality of tracking signals are equal or almost equal. a reference signal generator that provides the same timing, and a switch circuit that transmits the tracking signal to the driving means only during a period in which the reference signal generated by the reference signal generator is generated, and does not transmit the tracking signal during other periods; The configuration is such that the running of the magnetic tape is controlled by the output signal of the switch circuit.

Effect of the Invention With the above-described configuration, the amount of control of a plurality of tracking signals on one track is equal, and even if the tracks of the recorded track and the playback head are not completely parallel, the head can move to the center of the recorded track. will be traced on average.

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 shows an embodiment of the present invention, and FIG. 2 shows an example of a magnetic tape on which tracking signals described in the conventional example are recorded.
3 is an operational waveform diagram of the embodiment shown in FIG. 1, and FIG. 4 is a diagram showing the relationship between the tracks on the magnetic tape shown in FIG. 2 and the head locus.

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

In Fig. 1, 1a+1b is the head, 1 is the head la
, 1b are attached, 2 is a magnetic tape, 3 is a capstan motor that runs the magnetic tape 2 and serves as a driving means, 4 is an FGl that outputs a signal with a frequency proportional to the number of rotations of the capstan motor 3. 5 is a speed control circuit for controlling the rotation speed of the capstan motor 3,
8 is a synchronization signal detection circuit that detects a synchronization signal for detecting a tracking detection signal and outputs a pulse; 9 is a timing circuit that outputs a pulse after a certain period of time from the output pulse of the synchronization signal detection circuit 8; and 11 is a tracking detection circuit. 61.62 is the detection circuit 11 which detects the signal for
The output signal of synchronous signal detection circuit 8. A sample circuit samples each output pulse of the timing circuit 9; 63 is a subtracter that takes the difference between the output signals of the sample circuits 81 and 62; 1;
0 is a reference signal generator that generates pulses of approximately constant time width based on the output signal of a head switching signal generator (not shown) for switching and supplying the reproduced output signals of the heads la and lb to the amplifier. , 101 is the reference signal generator 1
0 is a switch circuit that is turned on only during the output reference pulse; 6 is an adder that adds the output signal of the subtracter 63 that has passed through the switch circuit 101 and the output signal of the speed control circuit 5;
is the capstan motor 3 based on the output of the adder 6 [f
This is a drive circuit that performs ll+. Note that the reference signal generator 10 is composed of a flip-flop 102 and a differentiation circuit 103.

In addition, in FIGS. 2 and 4, 21 is a truck;
A is the center line of the track, 21B is the center point of the track, 2
2a122b is the recording position of the tracking signal, 23 is the head trajectory, and 23A is the center line of the head trajectory.

The operation of the magnetic recording/reproducing apparatus constructed as described above will be described below with reference to FIGS. 1 and 3.

First, in FIG. 1, the rotary cylinder 1 has a head 1a.
, 1b are attached and rotate at high speed so that the heads 1a and 1b trace the tracks on the magnetic tape 2. The outputs of the heads la and lb are sent to the synchronization signal detection circuit 8.
A total of two sample pulses are generated, one when the synchronization signal on the track is detected by the synchronization signal detection circuit 8, and the other after a certain time delay by the timing circuit 9. On the other hand, among the output signals of the heads la and 1b, a trafking signal proportional to the amount of crosstalk with both adjacent tracks of the reproducing head is selectively detected by the detection circuit 11. The output of the detection circuit 11 is sampled and held by the sample circuits 61 and 62 using the two sample pulses mentioned above, and the difference is taken by the subtracter 63 to produce a tracking error signal e (the signal waveform is shown in FIG. 3e). shall be. The capstan motor 3 rotates at a nearly constant speed by the FG 4, the speed control circuit 5, and the drive circuit 7, which output an output signal with a frequency proportional to the number of rotations.
After the signal e1 selected in step 1 and the output of the speed control circuit 5 are added by an adder 6, the signal e1 is applied to the drive circuit 7, which functions to enable tracking of the heads 1a and 1b. In FIG. 2, examples of positions where tracking signals are recorded are shown by hatched areas 22a and 22b. In Figure 1, a
(The signal shown in FIG. 3a) is the head reproduction signal output, and b is the tracking signal detected by the detection circuit 11 (the signal waveform is shown in FIG. 3b). Similarly, C is the synchronization signal detection circuit 8
With the sample pulse output at , the timing circuit 9 outputs the sample pulse d (signal waveform is cod in Figure 3)
. The subtracter 63 takes the difference between the sample pulse circuits 81 and 62, and the result is output as a tracking error output e.

FIG. 3 shows the operation timing, and head reproduction signal output a1 tracking signal b1 sample pulse c1 sample pulse d are the same as those shown in FIG. 5 of the conventional example.

Further, in FIG. 1, the reference signal generator 10 includes a head 1.
A head switching signal f(
The signal waveform shown in FIG.
03 and output as a signal shown in FIG. 3 01. Further, the output pulse d of the timing circuit 9 is applied to the set terminal of the flip-flop 102 in the reference signal generator, and the output signal c1 of the differentiating circuit 103 is applied to the set terminal of the flip-flop 102 in the reference signal generator.
It is applied to the reset terminal of 02. Therefore, the output signal of the flip-flop 102 becomes the signal shown in FIG. 3 d1. When this reference signal d1 is at a high level, the switch circuit 10
1 is conductive and the output signal of the switch circuit 101 is as shown in FIG.
become that way.

In FIG. 3, the tracking error hold time C in the area 22b where the tracking detection signal is recorded in the track 21, and the tracking error hold time in the area 22a where the tracking detection signal is recorded in the track 21. The time it takes is almost the same.

The apparatus shown in FIG. 1 works so that the tracking error output e1 becomes zero, and as a result, the head 1a11b is controlled to pass through the center of the track 21.

In particular, even when the recorded track and the trajectory of the playback head are not parallel, that is, when the center line 21A of the track and the trajectory 231 of the head are not parallel in FIG. 4, the sections C and D shown in FIG. Since they are equal and their contributions to the control system are equal, control is performed so that the center line 23A1 of the head trajectory passes through the center point 21B of the track.

Effects of the Invention As described above, according to the present invention, by providing the pulse generating circuit 10 using the head switch as a reference signal, the tracking output time of two tracking signals on one track can be made almost equal. , the control amounts of these two tracking signals can be made almost equal, and the head can be traced correctly in the center of the track, thereby greatly improving playability.

In particular, when the recorded track and the trajectory of the playback head are not parallel, the contribution time of the two tracking areas becomes almost equal and their contributions to the control system are equal, so the center line of the head trajectory passes through the center point of the track. As a result, playability is significantly improved.

Further, according to the present invention, by using the head switching signal f as the reference signal of the pulse generating circuit 10, great effects can be obtained with a very small number of additional circuits.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a recorded magnetic tape, FIG. 3 is an operation waveform diagram of the embodiment of FIG. 1, and FIG. A schematic diagram showing the relationship between the track on the tape and the head trajectory in the embodiment of FIG. 1,
Fig. 5 is a configuration diagram for explaining the conventional example, and Fig. 6 is a configuration diagram for explaining the conventional example.
FIG. 7 is a schematic diagram showing the relationship between the track on the tape and the head trace in the embodiment shown in FIG. 5. 1...Rotating cylinder, la, lb...
...Head, 2...Magnetic tape, 3...
... Drive means, 8 ... Synchronization signal detection circuit, 9 ... Timing circuit, 11 ...
・Detection circuit, 61.62...Sample circuit, 63...Subtractor, 10...
Reference signal generator, 101...Switch circuit.

Claims (2)

[Claims] (1) A magnetic tape in which a tracking signal for detecting a tracking position by crosstalk from adjacent tracks and a synchronization signal for detecting the tracking signal are recorded at a plurality of predetermined positions on a track formed on a magnetic tape. A device for reproducing a tape, which includes a rotating cylinder to which a head is attached, a driving means for running the magnetic tape, and a synchronization signal detector for detecting a synchronization signal recorded on the magnetic tape and outputting a pulse. a timing circuit for outputting a pulse after a certain period of time after the synchronization signal detection circuit detects the synchronization signal; a detection circuit for obtaining the amplitude of the tracking signal; and a timing circuit for detecting the synchronization signal by detecting the output of the detection circuit. two sample circuits that sample and hold each of two pulses, an output pulse of the circuit and an output pulse of the timing circuit; a subtracter that takes the difference between the output signals of the two sample circuits and outputs a tracking error; a reference signal generator that provides a timing at which tracking error output times due to tracking signals are equal or almost the same; and a reference signal generator that transmits the tracking signal to the driving means only during the generation period of the reference signal generated by the reference signal generator; 1. A magnetic tape reproducing apparatus, comprising: a switch circuit that does not transmit data during a period of . (2) The magnetic tape reproducing apparatus according to claim 1, wherein the reference signal generator is configured to generate the reference signal based on the head switching signal.