JPS6011384B2 - Magnetic tape transfer control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a head-scanning magnetic tape recording and reproducing apparatus that scans the magnetic surface of a magnetic tape with a rotating head.
The present invention relates to a magnetic tape transport control system in which a magnetic head disposed on a head rotor of a rotary head can accurately scan information tracks formed on a magnetic surface of a magnetic tape.

Such magnetic tape recording and reproducing apparatuses are used as VTRs, data recorders, etc., and the configuration shown in FIG. 1 is generally used as a subsidiary.

That is, the magnetic tape 2 wound around the supply reel 1 is
The tape is guided into the vacuum column 4A via the tape guide 3, and then guided back into the vacuum column 4B via the head rotor 5, and then wound up by the take-up reel 6. However, the supply reel motor 7 rotates the supply reel motor 7, and the supply reel motor 7 is controlled by the supply reel servo circuit 9A based on the detection output of a photocell 8A provided on the side surface of the vacuum column 4A. The magnetic tape 2 inside is drawn in to a certain position, and the take-up roll 6 is similarly driven by a take-up roll motor 1 controlled by a take-up roll servo circuit 9B based on the detection output of the photocell 8B. Therefore, the position of the magnetic tape 2 rotated and drawn into the vacuum column 48 is kept constant. Therefore, the magnetic tape 2 is attracted by the negative pressure of the vacuum columns 4A and 4B, and a constant tension is applied to the magnetic tape 2.

On the other hand, the head rotor 5 is driven by a rotor motor 11, and its rotational speed is controlled by a rotor motor control circuit 12, and the rotational speed is determined according to a rotational speed designation signal applied to a rotational speed designation terminal 13.

In this example, the rotational speed of the head rotor 5 is changed each time the magnetic head 14 on the head rotor 5 faces the starting end of the information track on the magnetic surface 15 of the magnetic tape 2.
The detection is based on the time interval of the tack signal generated by the tack signal generator 16.

Also, a cap stand 1 for transferring the magnetic tape 2 is provided.
7 is rotated by a capstan motor 18, and the output of a rotation angular velocity detector 19 connected thereto is sent to an adder 2.
0 and the capstan motor 18 via the power amplifier 21, and since the switch 22 is off during recording, the rotational speed is controlled by the loop described above.

Note that during recording, the switch 23 is on the a side, and the recording/reproducing amplifier 2 is activated based on the output of the tack signal generator 16.
4 to the control head 25, and the moment the magnetic head 14 faces the female end of the information track on the magnetic surface 15 of the magnetic tape 2, the control signal is recorded on the control track 26.

Regarding the above recording, when playing back, the switch 22 is on and the switch 23 is on the b side, and in this case, control is performed.

-Ruhehe. The control signal reproduced from the control track 26 by the track 25 and the tack signal generator 16
The phase difference between the clock signal and the clock signal from The rotation is controlled so that the center of the rotation locus of the magnetic head 14 coincides with the center of the information track. That is, the tack signal indicates the moment when the magnetic head 14 faces the starting end of the information track,
Since the reproduction control signal indicates the center position of the information track, the phase difference between the tack signal and the reproduction control signal corresponds to the center of the rotation trajectory of the magnetic head 14 and the information at the moment when the magnetic head 14 faces the starting end of the information track. It is proportional to the amount of deviation from the center of the track, which is detected by the phase detector 27, and then a signal corresponding to the absolute value and suitability of the phase difference between the tack signal and the playback control signal is sent via the adder 20. By giving it to the power amplifier 21,
It is possible to control the "track deviation", that is, the deviation between the rotation locus of the magnetic head 14 and the information track to zero.

In order to make this control more stable, the rotational angular velocity signal of the capstan motor 18 detected by the rotational angular velocity detector 19 is added by an adder 201.

However, in the above-described control system based on the detection of intermittent "track deviation", since the tack signal generated only when the magnetic head 14 faces the starting edge of the information track is used, the capstan motor 18 generates a magnetic field. Correction of ``track deviation'' based on tape transport speed control is performed only when the magnetic head 14 faces the female end of the information track, and when the next magnetic head 14 faces the female end of the information track. Until now, the effect of the correction action was unclear, and the "track deviation" caused by the disturbance force acting on the magnetic tape 2 while the magnetic head 14 was scanning the information track could not be detected immediately, and it was difficult to correct the "track deviation". This method requires a long response time and has the drawback that "track misalignment" cannot be corrected at high speed and with high precision.

The present invention has the purpose of fundamentally eliminating such drawbacks of the conventional head.

A target value signal is obtained by calculating the sum or product of the rotation angle signal of the motor and the "track deviation" signal, and then this target value signal is compared with the rotation angle signal of the motor that transports the magnetic tape. The present invention provides a magnetic tape transport control system that corrects "track misalignment" with high response speed and high precision by driving a motor that transports the magnetic tape using an error signal obtained by the above method. The details of the present invention will be explained below with reference to FIG. 2 and subsequent figures showing embodiments.

In the configuration diagram of FIG. 2, the rotation of the rotor motor 11 and the tension of the magnetic tape 2 are controlled in the same way as in FIG. 1, but the rotation control of the capstan motor 18 is different from that in FIG. 11 and the cap stan motor 18 are connected to rotation angle detectors 31 and 32 such as an optical tachometer or a rotary encoder.

First, assuming that there is no slippage between the cap stan 17 and the magnetic tape 2 and that the amount of transfer of the magnetic tape 2 is proportional to the rotation angle of the cap stan motor 18, the transfer control of the magnetic tape 2 is performed as follows. It will be done. That is, the rotation angle of the cap stan motor 18 is detected by a rotation angle detector 32, and its pulse-like detection output is sent to a conversion circuit 3, which will be described later.
3, an analog signal proportional to the rotation angle of the capstan motor 18 is obtained, which is given to the subtracter 34 as a control amount signal, and is subjected to calculation with the target value signal from the adder 35. The difference is given to the power amplifier 21 via the subtracter 36 as an error signal.

However, in general, the cap stan motor 18 has a double integral characteristic between its electrical input and mechanical output, and a phase shift of 900 is generated in each integral characteristic, so the rotation angle of the cap stan motor 18 is For the error signal mentioned above,
There is a phase delay of 1800 degrees, and in order to stably control the capstan motor 18 using this error signal, it is necessary to give a signal proportional to the rotational angular velocity of the capstan motor 18 to the capstan motor 18 as a stabilizing signal, and the rotation A rotational angular velocity signal detected by the angular velocity detector 19 is provided to the power amplifier 21 via a subtracter 36.

Therefore, the rotation angle control system of the cap stan motor 18 performs a control operation in a direction in which the difference between the control amount signal from the conversion circuit 33 and the target value signal from the adder 25 becomes zero, and the target value signal and Control is performed so that the control amount signal matches the control amount signal. Therefore, if an analog signal proportional to the rotation angle of the head rotor 5 is given as a target value signal, the cap stan motor 18 will rotate at a rotation angle corresponding to the rotation angle of the head rotor 5. The amount of movement of the magnetic tape 2, which is proportional to the rotation angle, is also proportional to the rotation angle of the head rotor 5, and the head rotor 5 scans one scanning angle (the magnetic head 14 detects the beginning of the information track on the magnetic surface 15 of the magnetic tape 2). Each time the head rotor 5 rotates by the rotation angle required to scan from the end to the end,
By setting the target value signal assuming that the magnetic tape 2 is transferred by the width of one information track, the magnetic Transfer of tape 2 is performed.

However, since "track deviation" actually occurs, the "track deviation" is corrected by the following operation.

That is, on the magnetic surface 15 of the magnetic tape 2, a signal for detecting ``track deviation'' is alternately and repeatedly recorded as f2 at the starting end of the information track, and the frequency is different for each information track. The center of the information track is set at the center between the recorded frequencies f and 2, and after this is reproduced by the magnetic head 14, each frequency is also separated by the wave generator. , f2, when the reproduction output levels of each frequency f, and f2 are equal, it is detected that the center of the scanning trajectory of the magnetic head 14 coincides with the center of the information track.
The reproduction output of the magnetic head 14 is taken out via a "track deviation" detection circuit 37 consisting of a wave generator and a comparator,
This is used as a track deviation signal proportional to the amount of deviation between the center of the rotation locus of the magnetic head 14 and the center of the information track.

In addition, the recording status of the “track deviation” detection signal and
Regarding the “track deviation” detection circuit 37, please refer to
1125709 for details.

The output of the "track deviation" detection circuit 37 is given to the adder 35, while the output of the rotation angle detector 31 connected to the head rotor 5 is also applied to the rotation of the head rotor 5 by a conversion circuit 38 similar to the conversion circuit 33. This becomes a head rotor rotation angle signal which is an analog signal proportional to the angle, and is applied to the adder 35, and by adding the two, a target value signal is obtained. Therefore, if a "track deviation" occurs in the transport direction of the magnetic tape 2 with respect to the center of the information track, a track deviation value signal whose absolute value is equal to the amount of "track deviation" and has a negative polarity is added to the target value signal. Therefore, the target value signal decreases according to the amount of ``track deviation,'' and at this moment, the capstan motor 18 rotates in the opposite direction to the previous rotation direction.
It is driven by an angle equal to the amount of "track misalignment", thereby correcting the "track misalignment" that has occurred.

Note that after that, the rotation angle of the cap stan motor 18 is
Since the rotation angle of the head rotor 5 is controlled proportionally, scanning is performed in which the center of the rotation locus of the magnetic head 14 coincides with the center of the information track. Conversely, if a "track shift" occurs in the direction opposite to the transport direction of the magnetic tape 2 with respect to the center of the information track, the absolute value becomes '! Track shift”
Since a track deviation signal equal to the amount of positive polarity is added to the target value signal, the target value signal rises in accordance with the amount of "track deviation", and at this moment the capstan motor 18 causes the "track deviation" in the rotation direction. The "amount" is driven by an equal angle, thereby correcting any "track misalignment" that has occurred. FIG. 3 is a block diagram showing an embodiment using a direct tape transfer system between reels, in which the tension on the magnetic tape 2 is controlled by the rotation control of the supply reel motor 7, and the transfer of the magnetic tape 2 is controlled by the take-up reel motor 10. A rotation angular velocity detector 41 such as a rotation speed generator is connected to the supply reel motor 7, and a rotation angle detector 42 such as an optical tachometer or rotary encoder is connected to the take-up reel motor 7. A tension detector 43 such as a strain gauge is attached to the roller 3, and a rotational angular velocity detector 4
1. The tension control circuit 44 controls the supply reel motor 7 based on the outputs of the tension detector 43 and the rotational angular velocity detector 1 on the take-up reel motor 10 side, thereby controlling the tension.

However, in this case, the magnetic tape 2 on the supply reel 1
Since the rotational angular velocity changes depending on the winding speed, this information is stored in advance in the memo IJ' in the tension control circuit 44, and tension control is performed based on the contents. The details of the tension control circuit 44 are disclosed in Japanese Patent Application Publication No. 54-54083 filed separately by the present applicant. On the other hand, on the winding reel 6 side, the rotational angular velocity similarly changes depending on the winding thickness of the magnetic tape 2, and the amount of transport of the magnetic tape 2 is as follows.
Since the winding diameter of the winding reel 6 is horizontally equal to the rotation angle of the winding roll motor 10, it is necessary to measure the winding diameter of the winding reel.For this purpose, the pulse output of the rotation angle detector 42 is After counting by a rotation speed counter 45 such as a counter, the radius counter 46 consisting of an arithmetic circuit and a digital/analog converter converts the signal into an analog signal proportional to the winding diameter of the winding reel 6, and then it is sent to a multiplier 47. giving.

The multiplier 47 is given a signal proportional to the rotation angle of the take-up motor 10 from the conversion circuit 33, and the output of the multiplier 47 is a signal proportional to the rotation angle of the take-up motor 10. A signal proportional to the amount transferred is obtained.

Since a signal proportional to this amount of transfer is fed back to the power amplifier 21 via the subtracters 34 and 36, the amount of transfer of the magnetic tape 2 is determined by the rotation angle of the head rotor 5 indicated by the target value signal from the adder 35. controlled in proportion to.

That is, in this case, a proportional constant to the rotation angle of the winding roll motor 10 is obtained as a signal proportional to the winding diameter of the winding roll 6, and this signal is applied to the winding diameter of the winding roll 6. It is automatically adjusted according to the situation, and the saddle tab is directly placed between the reels.

Also in the transfer system, the magnetic tape 2 can be transferred by the width of one information track depending on the scanning angle of the head rotor 5. Note that when a "track deviation" occurs, the target value signal is adjusted according to the amount of the "track deviation" in the same manner as in FIG. 2, so that the "track deviation" is corrected.

FIG. 4 shows another embodiment of a device similar to that in FIG. The output is multiplied by the output of , and the output is used as the target value signal.

Therefore, the rate of increase in the target value signal with respect to the rotation angle of the head rotor 5, that is, the inclination with respect to the rotation angle of the head rotor 5, can be corrected by the correction value signal 52 according to the amount of "track deviation". Furthermore, since the control system is configured such that the rotation angle of the cap stan motor 18 matches the target value signal, if the rotation speed of the head rotor 5 is constant, the head rotor 5 at the target value signal
The transport speed of the magnetic tape 2 can be determined by the tilt angle component with respect to the rotation angle.

Note that the compensation value signal 52 is transmitted to the “track deviation” detection circuit 3.
When the output of the magnetic tape 7 is zero, the target value signal from the multiplier 53 is set to be the normal transport speed of the magnetic tape 2.

. Therefore, in FIG. 4, when the transport speed of the magnetic tape 2 becomes higher than the normal speed and the center of the scanning trajectory of the magnetic head 14 deviates from the center of the information track in the transport direction of the magnetic tape 2, negative polarity Since the track deviation signal is added to the correction value signal 52, a lower signal is given to the multiplier 53 than when the "track deviation" is zero, and the increase rate of the target value signal with respect to the rotation angle of the head rotor 5 is It becomes small,
As a result of the decrease in the transport speed of the magnetic tape 2, the speed is corrected to the normal speed.

Conversely, if the transport speed of the magnetic tape 2 decreases below the normal speed, a positive ``track misalignment'' occurs.
' signal is added to the compensation value signal 52, so the mirror oblique angle component with respect to the rotation angle of the head rotor 5 in the target value signal becomes larger than that at the normal speed, and the transport of the magnetic tape 2 is accelerated. Corrected to normal speed.

As described above, the configurations shown in FIGS. 2 to 4 operate, and the transport speed of the magnetic tape 2 and the "track deviation" are corrected reliably and quickly. However, in particular, the configurations shown in FIGS. Since the capstan motor 18 and the take-up motor 10, which serve as motors for transporting the tape 2, are continuously controlled by a closed-loop rotation angle control system, by widening the response frequency band of the control system,
“Track deviation” is corrected instantaneously.

In addition, in the configuration shown in FIG. 4, the transport speed of the magnetic tape 2 can be varied by adjusting the compensation value signal 52, and ``track misalignment'' is also corrected during variable speed transport, so that the speed at which information is reproduced increases. - Suitable for use in VTRs and the like that require motion operations and double-speed feed operations.

FIG. 5 shows the conversion circuits 33 and 3 in FIGS. 2 to 4.
8, the rotation angle detector 61 has first and second outputs 62, 63, and the phase difference between the two outputs 62, 63 varies depending on the rotation direction. The first output 6 is sent to the data terminal D of a D-type flip-flop circuit (hereinafter referred to as FFC) 64.
2, a second output 63 is provided to the clock terminal CP.

Now, when the rotation angle detector 61 rotates in the positive direction, the first
Assuming that the phase of the pulse train generated from the output 62 leads the phase of the pulse train generated from the second output 63 by 900,
In FFC64, the clock terminal CP becomes ``H'' after the data terminal D becomes "H" (high level).
FFC64 is set and keeps the output terminal Q at “H”,
The mode terminal U/D of the up/down counter (hereinafter referred to as UDC) 65 is set to "H" to enter an addition counting state.

On the other hand, the second output 63 is given to the count terminal CT of the UDC 65 as one of the first and second outputs 62 and 63, and the UDC 65 adds and counts the pulse train of the second output 63 and sends the result. It is applied to a digital-to-analog converter (hereinafter referred to as DAC) 66.

Therefore, an analog signal proportional to the continuous rotation angle of the rotation angle detector 61 is obtained from the DAC 66 as a rotation angle signal.

Furthermore, if the rotation angle detector 61 rotates in the opposite direction, the phase of the first output 62 is 90 degrees higher than the phase of the second output 63, contrary to the above.
0 delay, the sacrifice of phase difference is reversed, so FFC64's problem.

The back terminal CP becomes "H" when the data terminal D is "L" (low level), and the FFC64 maintains the reset state.
The UDC 65 is placed in a subtraction counting state. For this reason, UDC6
The count contents of 5 are subtracted, and along with this, the DAC
The output of 66 also decreases.

That is, from the output of the DAC 66, the rotation angle detector 61
A rotation angle signal proportional to the continuous rotation angle of is obtained, and increases or decreases depending on the rotation direction of the rotation angle detector 61.

When used as the conversion circuit 38 on the head rotor 5 side, the output of the UDC 65 corresponding to one scanning angle is taken out as a coincidence output by a decoder etc., and thereby the UDC
6 If you reset 5, the count for one scanning angle will be changed to UDC6.
5, and the number of digits can be significantly reduced.

As is clear from the above description, according to the present invention, the rotation angle control system of the magnetic tape transport motor is continuously controlled by its own rotation angle detector, the "track deviation" detection circuit on the head rotor side, and the rotation angle detector. Because it is configured as an open loop, "track misalignment" at startup and "track misalignment" due to disturbance force are immediately corrected at high speed and with high precision, and the recording against the information track or the information track is corrected immediately. Regeneration is accurate, and it is a nutritious tape for various uses.

It exhibits great effects in recording and reproducing devices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional example, FIGS. 2 to 4 are block diagrams showing an embodiment of the present invention, and FIG. 5 is a block diagram of the conversion circuit in FIGS. 2 to 4. 1... Supply reel, 2... Magnetic tape, 5...
Head rotor, 6... Winding roll, 10...
... Winding motor, 11 ... Rotor motor, 14
...Magnetic head, 15...Magnetic surface, 17...
... Capstan, 18 ... Capstan motor, 19 ... Rotation angular velocity detector, 21 ... Power amplifier, 31, 32, 42 ... Rotation angle detector, 33, 38
... Conversion circuit, 34, 36 ... Subtractor, 35, 51 ... Adder, 37 ... "Track deviation" detection circuit, 45 ... Rotation speed counter , 46...
...Radius counter "47, 53... Multiplier. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1. In a head-scanning magnetic tape recording and reproducing device that records and reproduces information by scanning the magnetic surface of a magnetic tape with a magnetic head on a head rotor, the head rotor rotates in proportion to the rotation angle of the head rotor. means for generating an angle signal; means for generating a track deviation signal proportional to the deviation between the center of the rotation locus of the magnetic head and the center of the information track on the magnetic surface of the magnetic tape; means for generating a target value signal by calculation based on a track deviation signal; means for generating a controlled variable signal proportional to the rotational angle of the motor for transporting the magnetic tape; means for generating a rotational angular velocity signal, means for generating an error signal by comparing the target value signal and the control amount signal, and a motor for transporting the magnetic tape based on the error signal and the rotational angular velocity signal. 1. A magnetic tape transfer control system comprising: means for generating a driving signal. 2. As a means for generating a head rotor rotation angle signal proportional to the rotation angle of the head rotor, the rotation angle signal is generated from the rotation angle detector in which the polarity of the phase difference is reversed depending on the rotation direction of the rotation angle detector that detects the rotation angle of the head rotor. Depending on the polarity of the first and second outputs, one of the first and second outputs is counted as either addition or subtraction, and after converting the counting result into an analog signal, the head rotor rotation angle signal is 2. A magnetic tape transfer control system according to claim 1, characterized in that a circuit for sending out a magnetic tape is used. 3. The magnetic tape transfer control method according to claim 1, wherein the calculation based on the head rotor rotation angle signal and the track deviation signal is performed by adding the two signals. 4. The magnetic tape transfer control system according to claim 1, wherein the calculation based on the head rotor rotation angle signal and the track deviation signal is performed by integrating the two signals. 5. The magnetic tape transport control system according to claim 1, wherein a take-up reel motor that rotates a take-up reel is used as the motor for transporting the magnetic tape. 6. The magnetic tape transport control system according to claim 1, wherein a capstan motor that rotates a capstan is used as the motor for transporting the magnetic tape. 7. As a means for generating a control amount signal proportional to the rotation angle of a motor that transports a magnetic tape, the rotation angle is such that the polarity of the phase difference is reversed depending on the rotation direction of a rotation angle detector that detects the rotation angle of the motor. Depending on the polarity of the first and second outputs generated from the detector, one of the first and second outputs is counted as either addition or subtraction, and the counting result is converted into an analog signal, and then the control is performed. 2. A magnetic tape transfer control system according to claim 1, characterized in that a circuit for sending out an amount signal is used.