JPH0312050A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To accurately perform consecutive recording from a specified track by selecting reference voltage as phase control voltage till the level of the phase control signal of a capstan motor attains the reference voltage just after a reproducing state is switched to a recording state. CONSTITUTION:The reference voltage 500 is selected and outputted to an adder 4 as the phase control voltage till the output signal 400 of an APC circuit 6 becomes within a specified range to the reference voltage 500 just after the reproducing state is switched to the recording state. At the time of starting recording, the effect of the varying output signal 400 of the APC circuit 6 is eliminated and the sudden variation of a capstan control signal 700 at the time of switching is suppressed, then the rotation of the capstan motor 1 is smoothly controlled. Therefore, a pattern recorded on a tape can be prevented from getting discontinuous before and after a recording start time, and the recording is started from the specified track at the time of consecutive recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a magnetic recording and reproducing apparatus such as a digital audio tape recorder (DAT) that records and reproduces information on a magnetic tape.

(Prior Art) Conventionally, in a magnetic recording/reproducing apparatus such as a DAT, a control system of a capstan for running a tape has a configuration as shown in FIG. That is, the capstan control system controls the speed and phase of the capstan motor.
tomatic Frequency Control
) loop and APC (Automatic Phas
It is equipped with an A-F (Auto Control) loop that controls the optimal position of the head that scans the tape.
matic Track Finding).

First, in the AFC loop, an FG signal 100 obtained from an FG (speed detector) 2 installed in a capstan motor 1 is input to an AFC circuit 3. This AFC circuit 3
A reference signal 200 is also input to the , and here, both signals 100
．． A difference of 200 is taken, and a speed control signal 300 proportional to the difference is input to the adder 4.

On the other hand, in the APC loop, the frequency of the FG multiplied signal 00 is divided by 1/N by the frequency divider 5 and input to the APC circuit 6. The reference signal 200 whose frequency has been divided by 1/N by the frequency divider 7 is also input to this APC circuit 6, and here, the difference between both signals 101 and 201 is taken, and a difference signal 400 proportional to the difference is generated. The signal is input to a comparison circuit 9 via a switch circuit 8 .

The comparison circuit 9 receives the input difference signal 400 and the reference voltage 50.
0, and the phase control voltage 600 is proportional to the difference.
is output to the adder 4. The adder 4 adds the aforementioned speed control signal 300 and this phase control voltage 600. Further, this added signal is integrated by a low-pass filter 10 to become a capstan control signal 700. After this capstan control signal 700 is amplified by the amplifier 11,
The input is input to the capstan motor 1, and the speed of the capstan motor 1 is controlled so that the signal 100 - the signal 200 - 0, and the phase of the capstan motor 1 is controlled so that the signal 400 - the signal 500 = It is controlled so that it becomes 0.

By the way, during recording, the switch circuit 8 is switched to the APC circuit '#16 side by the ATF/APC switching signal 60, and the above-described capsun control is performed. However, during reproduction, the switch circuit 8 is switched to the ATF circuit 12 measurement. The ATF circuit 12 controls the rotational phase of the capstan motor 1 so that the difference between the two leakage signals S1 and S2 from adjacent reverse azimuth tracks on the tape 50 becomes O as shown in FIG. be. Therefore, ATF
The circuit 12 inputs leakage signals S1 and S2 leaking from adjacent tracks during reproduction, corrects the difference between the two signals, and outputs a difference signal 800 proportional to this difference to the comparison circuit 9 via the switch circuit 8. Difference signal 80 input to the comparison circuit
0 and a reference voltage 500, and outputs a phase control voltage 600 proportional to the difference to the adder 4. Thereafter, the speed and phase of the capstan motor 1 are controlled in the same manner as during recording.

Here, in the capstan control system shown in FIG. 5, the reference signal 200 shown in FIG. 7(B) is created from the clock shown in FIG. is supplied to vessel 7. On the other hand, FG obtained by FG2
The signal 100 has the waveform shown in FIG. 7(C), and is input to the AFC circuit 3 and the frequency divider 5.

When the frequency division ratio of the frequency divider 5.7 is 2, the reference signal 200 and the FG signal 100 after frequency division become as shown in FIG. 7 (D> and FIG. 7 (E). If the period of the signal 100 is N1 and the period of the reference signal 200 is N2, AP
In the C loop, the capstan motor 1 is controlled so that N1-N2→0. Also, if the above two signals after frequency division are nl and n2, in the APC loop, nl n2''
The capstan motor 1 is controlled so that Δn→0.

FIG. 8 is a diagram showing an example of the configuration of a rotary head that performs recording and reproduction on the tape 50. Generally, as shown in FIG.
As shown in Fig. 8 (B), there are two heads AP installed around the drum 13 for recording and playback.
There is a 4-head system in which , AR, Bp, and BR are attached. However, the current DAT uses a two-head system shown in FIG. 8 (A>).

When performing so-called repeat recording in which recording is started from a predetermined track in the playback state using the two-head rotary head as described above, the following problems occur. That is, in the APC control system during playback, the switch circuit 8 is connected to the ATF circuit 12.
Since it is switched to the open loop, its output is 400
As shown in FIG. 9, is fluctuating at a constant cycle around the reference voltage 5VREF. Therefore, when changing from the playback state to the recording state, the switch circuit 8 is connected to the ATF circuit 12 side.
The circuit is switched to the PC circuit 6 side, but if at this moment the output value of the APC loop deviates greatly from the reference voltage 5VREF, the output waveform of the APC loop changes rapidly as shown in FIG. 9A. In such a state, the capstan phase control voltage 600 also fluctuates greatly, and the recording pattern becomes discontinuous before and after the start of recording, making it impossible to continue recording from a predetermined track. there were.

(Problems to be Solved by the Invention) As mentioned above, when repeating recording is performed using a conventional magnetic recording and reproducing device of this type, the ATF at the start of recording is caused by fluctuations in the output of the APC loop, which is in an open loop during reproduction. control to APC
There is a drawback in that the moment control is switched, the phase control voltage of the capstan motor causes unnecessary fluctuations, making it difficult to record from a predetermined track.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks, and provides a magnetic recording and reproducing apparatus that can accurately repeat recording from a predetermined track by suppressing unnecessary fluctuations in the capstan phase control voltage at the start of recording. is intended to provide.

[Structure of the invention]

(Means for Solving the Problems) The present invention controls the rotational speed and rotational phase of a capstan motor for running a magnetic tape during recording by a speed control system and a phase control system, and during playback, the rotational speed and rotational phase of a capstan motor for running a magnetic tape are controlled. In a magnetic recording/reproducing device having a capstan control system in which the rotational speed and rotational phase are controlled by the speed control system and the tracking control system, a mode detection means for detecting that the device changes from a reproduction state to a recording state; a reference voltage supply means for supplying a reference voltage to the capstan control system as a signal for controlling the phase of the capstan motor; determining means for determining whether the level of the phase control signal outputted from the control system is within a predetermined range in comparison with the reference voltage; When the determining means determines that the level of the phase control signal is within a predetermined range compared to the reference voltage, a phase control signal is generated by the phase control system as a signal for controlling the phase of the capstan motor. and a control means for supplying the capstan to the capstan control system.

(Function) In the magnetic recording and reproducing apparatus of the present invention, the mode detection means detects that the apparatus changes from the reproducing state to the recording state. The reference voltage supply means supplies a reference voltage to the capstan control system as a signal for controlling the phase of the capstan motor when the mode detection means detects that the apparatus changes from the reproduction state to the recording state. The determining means determines whether the level of the phase control signal output from the phase control system is within a predetermined range by comparing with the reference voltage. The control means controls the capstan when the determination means determines that the level of the phase control signal is within a predetermined range compared to the reference voltage after the mode of the apparatus changes from the reproduction state to the recording state. A phase control signal generated by the phase control system is supplied to the capstan control system as a signal for controlling the phase of the motor.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a capstan control system of a magnetic recording/reproducing apparatus according to the present invention. 1 is a capstan motor that rotates a capstan (not shown) that runs the tape; 2 is an FG (speed detector) that generates an FG signal 100 corresponding to the rotational speed of the capstan motor 1;
, 3 is an AFC circuit that takes the difference between the FG signal 100 and the reference signal 200, and 4 is an adder that adds the speed control signal 300 output from the AFC circuit 3 and the phase control voltage output via the switch circuit 16. , 5 is a frequency divider that divides the frequency of the FG signal 100, 6 is an APC circuit that takes the difference between the frequency-divided signal of the FG signal 100 and the frequency-divided signal of the reference signal 200, and 7 is a frequency divider that divides the frequency of the reference signal 200. 8 is a switch circuit that selects the output signal of either the ATF circuit 12 or the APC circuit 6; 9 is a comparison circuit that compares the signal output through the switch circuit 8 with a reference voltage 500; 10 is an adder 4 11 is an amplifier that amplifies the capstan control signal 700; 12 is an ATF circuit that takes the difference between leakage signals S1 and S2 from adjacent tracks;
A 14 compares the output signal of the APC circuit 6 and the reference voltage 500, and outputs a low level "L" when the difference is within a predetermined range, and outputs a high level "°H°" when the difference is outside the range.
PC lock detection circuit, 15 is APC lock detection circuit 14
APC loop opening/closing control signal 7 when the output is “°H’°
0 to the switch circuit 16, and this switch circuit 1
6 to the reference voltage 500 side, and when the output of the APC lock detection circuit 14 is L'', the microcomputer outputs the APC loop opening/closing control signal 700 to the switch circuit 16 and switches the switch circuit 16 to the comparison circuit 9 side. It is.

Next, the operation of this embodiment will be explained. An FG signal 100 obtained from an FG (speed detector) 2 attached to a capstan motor 1 is input to an AFC circuit 3.

A reference signal 200 is also input to this AFC circuit 3, and here, the difference between both signals 100 and 200 is taken, and a speed control voltage 300 proportional to the difference is input to an adder 4.

On the other hand, the frequency of the FG signal 100 is divided by 1/H by the frequency divider 5 and input to the APC circuit 6.

The reference signal 200 whose frequency has been divided to 1/H by the frequency divider 7 is also input to this APC circuit 6, and here, both signals 1
A difference of 01.201 is taken, and a difference signal 400 proportional to the difference is input to the comparison circuit 9 via the switch circuit 7. The comparison circuit 9 compares the input difference signal 400 with the reference voltage 500 and outputs a phase control voltage 600 proportional to the difference to the adder 4 via the switch circuit 16. Note that normally, the output of the APC lock detection circuit 14 is “
Therefore, the microcomputer 15
outputs a control signal 70 to switch the switch circuit 16 to the comparator circuit 9 side.

The adder 4 adds the aforementioned speed control signal 300 and this phase control voltage 600. Further, this added signal is integrated by a low-pass filter 10 to become a capstan control signal 700. The capstan control signal 700 is amplified by the amplifier 11 and then input to the capstan motor 1, and the speed of the capstan motor 1 is controlled so that the signal 100 - the signal 200 = O. The phase of the capstan motor 1 is controlled so that the signal 400-signal 500=0.

By the way, during recording, the switch circuit 8 receives the switching signal 6.
0, the circuit is switched to the APC circuit 6 side, and the above-described capstan control is performed. However, during reproduction, the switch circuit 8 is switched to the ATF circuit 12 side by the ATF/APC switching signal 60. The ATF circuit 12 controls the rotational phase of the capstan motor 1 so that the difference between the two leakage signals S1 and S2 from adjacent reverse azimuth tracks on the tape 50 becomes 0, as shown in FIG. . Therefore, the ATF circuit #112 inputs the leakage signals S1 and S2 leaking from adjacent tracks during playback, calculates the difference between the two signals, and sends a difference signal 800 proportional to this difference to the comparison circuit 9 via the switch circuit 8. Output. Comparison chart #19
compares the input difference signal 800 with the reference signal 500 and outputs a phase control voltage 600 proportional to the difference to the adder 4 via the switch circuit 16. Thereafter, the speed and phase of the capstan motor 1 are controlled in the same manner as during recording.

Furthermore, during playback, the switch circuit 8 is switched to the ATF circuit 12 side by the ATF/APC switching signal 60.
The output signal 800 of the ATF circuit 12 is input to the APC lock detection circuit fYI 14. However, since the value of this output maintains almost the same level as the reference voltage 500, the output of the APC lock detection circuit 14 is
It becomes. Therefore, the microcomputer 15 outputs the APC loop opening/closing control signal 70 to the switch circuit 16 to switch the switch circuit 16 to the comparator circuit 9 side. Therefore, in this case, tracking control is performed using the ATF loop as in the conventional example.

Next, the moment the playback state switches to the recording state, the ATF
The switch circuit 8 is switched to the APC circuit 6 side by the /APC switching signal 60. At the same time, the microcomputer 15 unconditionally outputs the APC loop opening/closing control signal 70 to the switch circuit 16 to switch the switch circuit 16 to the reference voltage 500 side. Therefore, at the start of recording, the reference voltage 500 is output as a phase voltage to the adder 4 via the switch circuit 16, where it is added to the speed control signal 300 output from the AFC circuit 3, and then input to the low-pass filter 10. Therefore, at the start of recording, the reference voltage 500, which is almost the same as the output signal of the ATF circuit 12, is supplied as the phase control voltage, so the capstan motor control signal 700 that controls the capstan motor 1 is unnecessary as shown in FIG. capstan motor 1 without causing any fluctuation.
will be subject to smooth control.

On the other hand, when changing from the playback state to the recording state as described above, the AP
The output signal 400 of the C circuit 6 is passed through the switch circuit 8 to the A
Since the signal is input to the PC lock detection circuit 14, the APC lock detection circuit 14 compares the output signal 400 of the APC circuit 6 with the reference voltage 500. Normally, at the start of recording when the switch circuit 8 is switched to the APC circuit 6 side, the output signal of the APC circuit 6 has a large difference with respect to the reference voltage 500, so the output signal of the APC lock detection circuit 14 is "H°". The microcomputer 15 outputs the APC loop opening/closing control signal 70 to the switch circuit 16 so that the switch circuit 16 is kept switched to the reference voltage of 500 volts.
When the output signal of the PC circuit 6 converges and approaches the level of the reference voltage 500 and the difference is within a predetermined range, the APC
The output of the lock detection circuit 14 becomes °L'°, and upon receiving this, the microcomputer 15 outputs the APC loop opening/closing control signal 70 to the switch circuit 16, and switches the switch circuit 16 to the comparison circuit 9 side. The phase control voltage 600 output from the comparator circuit 9 is input to the adder 4 via the switch circuit 16. At this time, since the phase control voltage 600 outputted from the comparison circuit 9 is within a predetermined range with respect to the level of the reference voltage 500, the capstan motor control signal 700 is output as shown in FIG.
Since there is no unnecessary fluctuation in the capstan motor 1, the capstan motor 1 is smoothly controlled by the AFC loop and the APC loose.

According to this embodiment, immediately after switching from the reproduction state to the recording state, the output signal 400 of the APC circuit 6 is set to the reference voltage 50.
Since the reference voltage 500 is selected as the phase control voltage and output to the adder 4 until it falls within a predetermined range with respect to 0, the influence of the varying output signal 400 of the APC circuit 6 is eliminated at the start of recording. Rapid fluctuations in the capstan motor control signal 700 at the time of switching can be suppressed, and the rotation of the capstan motor 1 can be smoothly controlled.

Therefore, it is possible to prevent the recording pattern on the tape from becoming discontinuous before and after the recording start time, and it is possible to start recording from a predetermined track during splicing recording.

By the way, the recording methods in DAT can be roughly divided into IT
There are P mode and 1.5TP mode.

The ITP mode is a method in which, during recording, a new track is overlaid on 1/3 of an adjacent recorded track. When this method is adopted, the width of each recorded track is 2/3 of the head width. Also, 1.5
The TP mode is a method in which a new track is recorded so as to be in contact with an adjacent recorded track during recording, and in this method, the recorded track width is equal to the head width.

Here, the state of continuous recording using two heads employing the ITP mode method is as shown in FIG. That is, since tracking control is performed by the ATF loop during reproduction, the locus of the center portion of the head is controlled so as to pass through the center of the track. In the ITP mode, the head width is 1.5 times the track width, so when the head passes through tracks with the same azimuth, it also automatically passes through adjacent reverse azimuth tracks as shown in FIG. When the ATF is ideal, its width is 1/6 of the head width (1/4 of the track width), as shown by the dark areas in FIG. Therefore,
Immediately after switching from the playback state to the recording state, the newly recorded first track erodes the adjacent track by 1/6 of the head width, making the track pattern discontinuous, as shown by W in Figure 2. Therefore, it is not possible to perform smooth transcription using only the configuration of the embodiment shown in FIG. As shown in FIG. 3, another embodiment for preventing this is configured by providing an offset of 1/6 of the head width in advance during playback, and changing the locus of the center of the head by the amount of offset from the center line of the track. If tracking control is performed by shifting, recording can be started from a predetermined track position. However, in Figures 2 and 3, T indicates the track pitch, R indicates the head trajectory during playback, W indicates the head trajectory during recording, and the dark areas indicate the reverse azimuth passing portion. .

Note that in a DAT that uses the 1.5TP mode system, the track width and head width are the same as described above, so there is no problem that occurs with the DAT that uses the ITP mode system, as shown in Figure 1. It is possible to perform smooth transcription only with the configuration of the illustrated embodiment.

〔Effect of the invention〕

As described above, according to the magnetic recording and reproducing apparatus of the present invention,
It is possible to suppress unnecessary fluctuations in the capstan phase control voltage at the start of recording, and to accurately repeat recording from a predetermined track.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the tracking control system of the magnetic recording/reproducing apparatus of the present invention, FIG. 2 is a diagram showing an example of a head trajectory when an ITP mode recording method is adopted, and FIG. 4 is a diagram showing an example of a head trajectory for explaining another embodiment of the present invention, and FIG.
A waveform diagram showing an example of changes in the capstan motor control signal when switching from F to APC loop, Fig. 5 is a block diagram showing an example of a conventional magnetic recording/reproducing device, and Fig. 6 explains tracking control. Fig. 7 is a time chart of various signals generated in the circuit shown in Fig. 5, and Fig. 8 is an example of the configuration of a conventional general rotary head. FIG. 9 is a diagram showing an example of the output signal waveform of the APCUgJ path shown in FIG. 5 in open loop and closed loop. 1... Capstan motor 3... AFC circuit 4.
...Adder 6...APC circuit 8.16...Switch circuit 9...Comparison circuit 12.
・・ATF circuit 14 ・APC lock detection circuit 15 ・Microcomputer

Claims (1)

[Claims] During recording, the rotational speed and rotational phase of the capstan motor for running the magnetic tape are controlled by a speed control system and a phase control system, and during reproduction, the rotational speed and rotational phase of the capstan motor are controlled by the rotational speed and rotational phase of the capstan motor that runs the magnetic tape. In a magnetic recording/reproducing device having a capstan control system controlled by a speed control system and a tracking control system, a mode detecting means detects when the device changes from a reproducing state to a recording state; a reference voltage supply means for supplying a reference voltage to the capstan control system as a signal for controlling the phase of the capstan motor when a change from the reproduction state to the recording state is detected; determining means for determining whether the level of the phase control signal is within a predetermined range in comparison with the reference voltage; and after the mode of the apparatus changes from the reproduction state to the recording state, the determination means When it is determined that the level of the phase control signal is within a predetermined range compared to the reference voltage, the phase control signal generated by the phase control system is used as a signal for controlling the phase of the capstan motor. 1. A magnetic recording and reproducing device comprising: a control means for supplying power to a stun control system.