JPH05114277A - Magnetic recording reproducing apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] The detection of the tape transfer amount using the CFG signal is
It should not be affected by slippage between the magnetic tape and the capstan shaft. The control circuit 19 operates according to the setting of the recording suspension mode, and the count value of a counter 20 that counts the CFG signals from the CFG signal generator 5 is fetched. When the count value reaches a predetermined value, the control circuit 19 stops the capstan motor 3 and turns off the magnetic tape 1.
To stop. On the other hand, the counter 21 is reset by the CTL signal from the control head 6,
Count the CFG signals. The count value becomes maximum N if there is no slip between the magnetic tape 1 and the capstan shaft. If there is such slip, the counter 21 exceeds this maximum value N and the counter 21 outputs a signal. The switch 22 is turned off by this signal, the count of the counter 20 is prohibited, and the count value is corrected by the slip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus for driving a magnetic tape with a capstan, and more particularly, when rewinding and transporting a predetermined amount of a magnetic tape when recording is temporarily stopped in continuous recording. The present invention relates to a suitable method for detecting a tape transfer amount.

[0002]

2. Description of the Related Art In a conventional helical scan type magnetic recording / reproducing apparatus, it is possible to carry out continuous recording by resuming recording by interrupting recording up to now to a recording paused state (recording paused state). However, when the recording suspension state is entered in this way, a certain amount of rewinding of the magnetic tape is performed. Then, with respect to this rewinding amount, when the recording paused state is released and the recording is restarted, first, the tracking control for tracking the magnetic head on the existing track is performed, and thereafter, the recording is started. The rewinding of the magnetic tape is necessary to be able to perform such tracking control, and thus the rewinding amount of the magnetic tape must be set with high accuracy.

As a method for detecting the running amount (tape transfer amount) of a magnetic tape for continuous shooting recording, as described in Japanese Patent Publication No. 63-62813, the reproduction from the lower end of the magnetic tape is conventionally performed. Control signal (hereinafter C
There is known a method of counting the TL signal) and detecting the traveling amount from the counted value. However, according to this method, the amplitude of the CTL signal changes significantly when the recording state is changed to the reproducing state (5 V for recording and 5 mV for reproducing).
Therefore, the reproduced CTL signal may not be detected in some cases.

On the other hand, for example, Japanese Patent Laid-Open No. 64-596.
As described in Japanese Patent Laid-Open No. 58-58, a signal (hereinafter, referred to as a CFG signal) having a frequency proportional to the rotation speed of the capstan motor, which is generated with the rotation of the capstan motor, is counted, and the tape transfer amount is calculated from the count value. There are known methods for detecting. Since the CFG signal has a constant amplitude regardless of the recording / reproducing state, the above problem does not occur.

[0005]

By the way, in general, there is a slip between the magnetic tape and the capstan shaft,
Moreover, this slip changes according to the load applied to the magnetic tape. When there is no such slip, the above-mentioned conventional technique using the CFG signal is an effective method for detecting the running amount of the CFG signal because the wave number of the CFG signal is proportional to the running amount of the magnetic tape. However, in general, there is a slip between the magnetic tape and the capstan shaft, so that C
The wave number of the FG signal is no longer proportional to the running amount of the magnetic tape, and the conventional technique cannot accurately detect the tape moving amount.

The object of the present invention is to solve the above problems and to prevent slippage between the magnetic tape and the capstan shaft.
It is an object of the present invention to provide a magnetic recording / reproducing apparatus capable of accurately detecting the tape transfer amount.

[0007]

In order to achieve the above object, the present invention provides a magnetic recording / reproducing apparatus in which a CFG signal is counted by a counter to detect a tape transfer amount. Detecting means for detecting a slip state between the tape and the tape, and adjusting means for adjusting the supply of the capstan frequency signal to the counter according to the detection result of the detecting means are provided.

[0008]

The slip detected between the magnetic tape and the capstan shaft is detected, and C of the counter is detected according to the detection result.
The count value of the FG signal is adjusted. When there is no slip, the tape transfer amount is proportional to the wave number of the CFG signal, so the counter counts this CFG signal as it is, but when there is slip, the running speed of the magnetic tape with respect to the frequency of the CFG signal. Becomes slower and the counter counts the CFG signal as it is, the count value of the counter becomes larger than the actual tape transfer amount.
Therefore, in the present invention, if there is slippage, the count value of the counter is adjusted accordingly, and the count value of the counter is always proportional to the tape transfer amount.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention, in which 1 is a magnetic tape, 2 is a drum motor, 3 is a capstan motor, 4 is a pinch roller, 5 is a CFG signal generator, 6 is a control head, 7 and 8 are amplifiers, 9 is a tack head, 10 is a DFG signal (drum frequency signal) generator, 11 and 12 are amplifiers, 13 and 14
Is a motor drive amplifier, 15 is a speed control circuit, 16 is a phase control circuit, 17 is a vertical synchronization signal input terminal, 18 is a recording pause signal input terminal, 19 is a control circuit, and 20 and 21.
Is a counter, 22 and 23 are switches, 24 is a reference signal generator, 25 is a phase control circuit, 26 is a speed control circuit, 27
Is a rotation phase information signal generator, and 28 is a switch.

Referring to FIG. 1, the control of the drum motor 2 and the capstan motor 3 during recording will be described first.
When the drum motor 2 rotates, the DFG signal is generated by the DFG signal generator 10. The DFG signal is amplified by the amplifier 12 and then supplied to the speed control circuit 15 to be converted into a voltage proportional to its frequency, and further compared with a constant reference voltage to obtain a speed control voltage corresponding to the error. can get. Further, the tack head 9 detects a tack signal representing the rotation phase of the drum motor 2. The tack signal is amplified by the amplifier 11 and then amplified by the phase control circuit 16
To the video signal to be recorded and compared with the vertical synchronizing signal input from the input terminal 17 to obtain a phase control voltage proportional to the phase difference. Then, the speed control voltage from the speed control circuit 15 and the phase control voltage from the phase control circuit 16 are added, and the motor drive amplifier 13
Is supplied to. The motor drive amplifier 13 supplies a current proportional to the supply voltage to the drum motor 2. As a result, the drum motor 2 rotates so that the voltage converted from the DFG signal becomes equal to the reference voltage and is in phase synchronization with the vertical synchronizing signal from the input terminal 17.

On the other hand, when the capstan motor 3 rotates while the magnetic tape 1 is sandwiched between the capstan shaft and the pinch roller 4, the CFG signal generator 5 generates a CFG signal. The CFG signal is amplified by the amplifier 7 and then supplied to the speed control circuit 26 to be supplied to the speed control circuit 15
Similarly to, a speed control voltage is formed. Also, this CFG
The signal is supplied to the rotational phase information signal generator 27, where it is subjected to processing such as frequency division to form a rotational phase information signal. At the time of this recording, the switch 23 is connected to the b side, and this rotation phase information signal is supplied to the phase control circuit 25 and is proportional to the phase difference from the reference signal of the constant frequency supplied from the reference signal generator 24. A phase control voltage is generated. This phase control voltage and the speed control voltage from the speed control circuit 26 are added and supplied to the motor drive amplifier 14. The motor drive amplifier 14 supplies a current proportional to the supply voltage to the drum motor 2. As a result, the voltage converted from the CFG signal becomes equal to the reference voltage, and the rotation phase information signal from the rotation phase information signal generator 27 and the reference signal from the reference signal generator 24 have a constant phase relationship. Thus, the capstan motor 3 rotates.

As described above, when the drum motor 2 and the capstan motor 3 rotate, the magnetic tape 1 runs at a constant speed, and the magnetic head on the drum (not shown) rotated by the drum motor 2 scans the magnetic tape 1. Then, the video signal is recorded. Although not shown, the CTL signal is recorded on the magnetic tape 1 by the control head 6 during this recording.

During reproduction, a reference signal having a constant frequency and a constant phase is supplied from the input terminal 17, and the switch 2
3 is connected to the a side and the CTL signal from the amplifier 8 is supplied to the phase control circuit 25, and the same control as that at the time of recording is performed.

Next, the recording pause operation (recording pause operation) will be described with reference to FIG. The operation of the magnetic tape 1 when the recording is temporarily stopped is shown in FIG.

That is, when the running direction of the magnetic tape 1 at the time of recording is the forward direction and the opposite running direction is the reverse direction,
When the magnetic tape 1 travels in the normal direction and the recording operation is performed, when the recording pause signal of "H" (FIG. 2B) is input from the input terminal 18, the control circuit 19 operates and the switch 28 is turned on. When turned off, the control signals from the speed control circuit 26 and the phase control circuit 25 are cut off, and instead the control signal from the control circuit 19 is supplied to the motor drive amplifier 14. This control signal causes the magnetic tape 1 to enter the stopped state at the rising edge of the recording pause signal, as shown in FIG. 2 (a), and thereafter, the tape is rewound for a certain period of time to enter the reverse running state. And then stop. This stopped state continues while the recording pause signal is "H". When the recording pause signal becomes "L", the magnetic tape 1 is in the normal rotation running state as shown in FIG. 2A, and is shown in FIG. 2C for a certain period from the trailing edge of the recording primary stop signal. The recording operation is restarted after the phase adjustment period.

The tape rewinding is performed here.
Even if the magnetic tape 1 is stopped at the point where the recording is stopped and the recording is restarted from this position, the capstan motor 3 cannot be instantaneously started up. Therefore, normal recording is performed during the rising period of the capstan motor 3. This is because the recording of the rising period of the capstan motor 3 can be postponed.

By the way, when the re-recording is started after the recording pause period, the recording start position does not partially overlap with the existing recording area, or an unrecorded portion does not occur between the end of the existing recording area. Therefore, in order to perform good continuous recording so that new recording is started from the end of the existing recording area, in order to perform good continuous recording, the magnetic field when the recording temporary stop signal is “H” is set in the temporary recording operation. FIG. 2 after the amount of reverse running of the tape 1 becomes “L” for the recording pause signal.
It must be equal to or more than the running amount of the magnetic tape 1 in the forward direction in the phase matching period shown in (c), and it must be an exactly constant amount.

As a method for making the traveling amount of the magnetic tape 1 in the reverse direction constant, there is the conventional method described above, and this method is used when there is no slip between the capstan shaft and the magnetic tape 1. But there is no problem. However, if there is such a slip, this method cannot be adopted as described above. In this embodiment, even if there is a slip between the capstan shaft and the magnetic tape 1, the tape running amount can be accurately detected without being affected by the slip, thereby enabling good continuous recording. It is a thing.

When there is no slip between the capstan shaft and the magnetic tape 1, the running amount (tape transfer amount) of the magnetic tape 1 is proportional to the integrated value of the pulse number of the CFG signal from the CFG signal generator 5. To do. Therefore, the running amount of the magnetic tape 1 can be known by counting the CFG signal. Therefore, in this embodiment, in FIG.
The counter 20 counts the CFG signal from the amplifier 7, the control circuit 19 detects the running amount of the magnetic tape 1 from the count value, and controls the capstan motor 3 during the recording pause as described above.

However, in reality, slippage occurs between the capstan shaft and the magnetic tape 1 due to running load and the like. Therefore, the magnetic tape 1 may not travel at a speed corresponding to the rotation speed of the capstan motor 3. In such a case, the running amount of the magnetic tape 1 can be accurately measured by simply counting the CFG signal. I can't figure it out. Therefore, in this embodiment, the counter 2 which detects the slip and counts the CFG signal in accordance with the slip is detected.
The correction value is added to the count value of 0, and the magnetic tape 1
The amount of travel of the vehicle can be accurately grasped. This point will be described below.

When there is no slip between the capstan shaft and the magnetic tape 1, the CTL signal and the CFG signal have a proportional frequency relationship. Therefore, the number of pulses of the CFG signal existing in one cycle of the CTL signal is constant (
N). If there is a slip between the capstan shaft and the magnetic tape 1, the running amount of the magnetic tape 1 is small relative to the rotation amount of the capstan motor 3, so the number of pulses of the CFG signal existing in one cycle of the CTL signal. Is larger than N. This is because the rotation speed of the capstan motor 3 is constant and the frequency of the CFG signal is constant, so that the cycle of the CTL signal becomes long. On the contrary, when the frequency of the CTL signal is used as a reference, when there is a slip between the capstan shaft and the magnetic tape 1, the frequency of the CFG signal becomes higher than when there is no slip.

Therefore, while the counter 21 is reset by the CTL signal from the amplifier 8, the CF from the amplifier 7 is reset.
When the G signal is counted and the count value is N or less, the switch is turned on, but when it exceeds N, the switch 22 is turned off, and then the counter 21 is reset and the switch 22 is turned on. , CF on counter 20
Prevent the G signal from being supplied. As a result, the counter 20 is always supplied with N CFG signals per cycle of the CTL signal. This is counter 20
When N CFG signals are supplied to, the magnetic tape 1 has moved by the recording interval of the CTL signals recorded therein. Therefore, even if there is a slip between the capstan shaft and the magnetic tape 1 and the size of the slip is large, the running amount of the magnetic tape 1 can be reliably measured in the recording interval unit of the CTL signal. It can be detected.

A reference value for the prescribed tape rewinding amount is set in advance in the control circuit 19, and the count value of the counter 20 is compared with this reference value. When the two match, the control circuit 19 stops the capstan motor 3 via the motor drive amplifier 14 and stops the magnetic tape 1. In this way, the magnetic tape 1 is rewound by a prescribed amount even if there is a slip between the capstan shaft and the magnetic tape 1.

FIG. 3 shows the effect of the above correction operation, in which the horizontal axis is the time axis in the cycle unit of the CTL signal,
The vertical axis represents the count value of the counter 20, A is a theoretical value (a count value that accurately represents the tape running amount), B is an actual measurement value without correction (a count value of the counter 20 when the above correction operation is not performed), and C is It is a corrected actual measurement value (count value of the counter 20 when the above correction operation is performed).

In the figure, when there is no correction operation as described above, as is clear by comparing the theoretical value A with the uncorrected actual measurement value B, the count value of the counter 20 greatly deviates from the theoretical value A with the passage of time. To go. On the other hand, when the above correction operation is performed, C within one cycle of the CTL signal
When the number of pulses of the FG signal exceeds N, the count is stopped without supplying the CFG signal to the counter 20, and the count value within one cycle of the CTL signal is fixed to N, so that the corrected measured value C is obtained. As shown, the corrected measured value C matches the theoretical value A for each cycle of the CTL signal. In this way, the tape running amount can be accurately obtained.

[0026]

As described above, according to the present invention,
Even if a slip occurs between the magnetic tape and the capstan shaft, the tape transfer amount can be accurately detected. Therefore, even in splicing recording, the joint between the old recording unit and the new recording unit is good. As a result, the image distortion there can be prevented, and the performance is greatly improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording / reproducing apparatus according to the present invention.

FIG. 2 is a timing chart showing the operation of the embodiment shown in FIG.

FIG. 3 is a diagram showing an effect of the embodiment shown in FIG.

[Explanation of symbols]

 1 magnetic tape 3 capstan motor 4 pinch roller 5 CFG signal generator 6 control head 18 recording pause signal input terminal 19 control circuit 20, 21 counter 22 switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Takamiya 2-15-12 Nishishimbashi, Minato-ku, Tokyo Stock company Hitachi, Ltd. Consumer Electronics Business Headquarters

Claims (2)

[Claims] 1. A magnetic recording / reproducing apparatus comprising a counter for counting a capstan frequency signal having a frequency proportional to the rotational speed of a capstan motor, and determining the running amount of a magnetic tape from the count value of the counter. Detecting means for detecting a slip state between the capstan shaft and the magnetic tape, and adjusting means for adjusting the supply of the capstan frequency signal to the counter according to the detection result of the detecting means are provided. A magnetic recording / reproducing apparatus, which is configured so as to be able to prevent a determination error of a running amount of the magnetic tape due to a slip between the capstan shaft and the magnetic tape. 2. The detecting device according to claim 1, wherein the detecting means counts the capstan frequency signal while being reset by a control signal reproduced from the magnetic tape, and outputs the signal when the count value exceeds a predetermined number. The magnetic recording / reproducing apparatus, wherein the adjusting means prohibits the supply of the capstan frequency signal to the counter during the period of the output signal of the counter.