JP2734712B2 - Capstan motor speed controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A Field of Industrial Use B Outline of the Invention C Prior Art D Problems to be Solved by the Invention E Means for Solving the Problems F Operation G Example G-1 Configuration and Operation (FIGS. 1 to 3) G-2 Modifications H Effects of the Invention A Industrial Field of the Invention The present invention relates to a plurality of different reproduction modes for reproducing information from a tape on which information is recorded under each of a plurality of different recording modes. And a capstan motor speed control device provided in an information reproducing system capable of taking at least two different tape running speeds during reproduction.

B SUMMARY OF THE INVENTION The present invention provides a plurality of reproduction modes for reproducing information from a tape on which information is recorded under each of a plurality of recording modes in which information is recorded at different recording tape running speeds. In a capstan motor speed control device provided in an information reproducing system capable of taking at least two different tape running speeds during reproduction, a speed detection device having a frequency corresponding to a rotation speed of a capstan motor. A point in time at which the count value of the clock pulse from the start time of each cycle of the signal reaches a predetermined value is detected, and a level change voltage that changes the level according to the count value of the clock pulse from the detected time is formed. The sample and hold output at the end of each cycle of the speed detection signal for the level change voltage is obtained and the speed control Forming and controlling the rotation speed of the capstan motor based on the drive control of the capstan motor based on the speed control voltage, the speed detection signal has a different frequency according to the tape running speed during reproduction, and By changing the clock pulse to have a different frequency according to the reproducing mode, the rotation speed of the capstan motor varies over a relatively wide range according to the reproducing mode or the tape running speed during reproduction. Is relatively slow, the rotational speed of the capstan motor can be controlled with a stable servo control system.

C Prior Art A so-called digital signal is recorded on a recording medium and reproduced from the recording medium by digitizing an audio signal.
In the R-DAT system, an audio signal digitized by using a method such as pulse code modulation (PCM) is converted by a plurality of rotating magnetic head units.
A plurality of rotating magnetic heads read the digitized audio signal from the magnetic tape recorded with the inclined track on the magnetic tape and the digitized audio signal recorded with the inclined track, and the readout processing is performed. To be offered.

The reproducing system in such an R-DAT system is provided with a signal reading mechanism. In the signal reading mechanism, as shown in FIG. 3, a pair of rotating magnetic heads 10 and 11 are provided with a drum motor. Drum rotated by 12
13 is attached at a position opposing the rotary shaft. These rotating magnetic heads 10 and 11 have their respective magnetic gap portions facing the outer peripheral surface of the drum 13, and when rotated with the rotation of the drum 13, the drum 13
Around the rotation axis of the drum 13, for example, about
A magnetic tape Tr on which a digitized audio signal is recorded with a sloping track is alternately scanned along the sloping track. And read the digitized audio signals from the read output signals Aa and Ab
Is sent. The magnetic tape Tr is caused to travel by a capstan 15 rotated by a capstan motor 14 and a pinch roller 16 which is in contact with the capstan 15. The drum motor 12 has a drum
Drum motor to rotate 13 at a predetermined speed
A drum servo control circuit section 17 for controlling the rotation of the motor 12 is provided, and the capstan motor 14 is provided with a capstan motor for running the magnetic tape Tr at a predetermined speed.
A capstan servo control circuit 18 for controlling the rotation of 14 is provided.

For example, the reproduction system including the signal reading mechanism as described above is digitized by taking a standard recording mode (SP mode) in which the magnetic tape Tr records signals under the standard tape running speed. Playback mode (SP playback mode) in which recorded audio signals are recorded, and long-time recording mode (LP mode) in which the magnetic tape Tr records signals at a tape traveling speed of 0.5 times the standard speed. Playback mode (LP playback mode) in which audio signals digitized and recorded are recorded, and magnetic tape Tr
Takes a plurality of different playback modes such as a playback mode (soft tape playback mode) in which a digitized audio signal is recorded with the tape running speed set to 1.5 times the standard speed. In the reproduction of signals from the magnetic tape Tr in each reproduction mode, a standard reproduction state in which the tape traveling speed is set to the standard speed, and a double speed reproduction in which the tape traveling speed is set to twice the standard speed. The state is selectively taken. And SP
The rotation speed of the drum 13 and the running speed of the magnetic tape Tr differ depending on each of the playback mode, the LP playback mode, and the soft tape playback mode, and further, according to each of the standard playback state and the double speed playback state. The drum servo control circuit unit 17 and the capstan servo control circuit unit
The control by which the drum 13 and the magnetic tape Tr take the rotation speed and the running speed according to the SP playback mode, the LP playback mode, or the soft tape playback mode under the standard playback state or the double speed playback state, respectively, by the Done.

Among the controls by the drum servo control circuit unit 17 and the capstan servo control circuit unit 18, the SP playback mode under the standard playback state or double speed playback state on the magnetic tape Tr by the capstan servo control circuit unit 18, The control for increasing the running speed according to the LP playback mode or the soft tape playback mode is performed by, for example, configuring a capstan motor speed control circuit as shown in FIG.

The capstan motor speed control circuit shown in FIG. 4 has a frequency corresponding to the rotation speed of the capstan motor 14 obtained from the frequency generator 21 provided in the capstan motor 14. The signal FGs is converted into a rectangular wave signal FFi by the waveform shaping unit 22, and the rectangular wave signal FFi is supplied to the pulse generation unit 23 as a speed detection signal. The clock pulse CL from the terminal 24 is also supplied to the pulse generation unit 23, and the pulse generation unit 23 starts counting the clock pulses CL from the start of each cycle of the rectangular wave signal FGi, and the count value is set to a predetermined value. The time required to reach the value is measured, and a pulse signal Px having a leading edge at the start of each cycle of the rectangular wave signal FFi and having a pulse width corresponding to the measured time is formed. The predetermined value of the count value of the clock pulse CL in the pulse generation unit 23 is obtained from the data selector 25 by the pulse generation unit 23.
Is determined based on the data Dx supplied to.

The data selector 25 has a playback mode signal Sa indicating that the LP playback mode is taken under the standard playback state from the terminal 26, and an SP playback mode under the standard playback state from the terminal 27. Or in a 2x speed playback state
A playback mode signal Sb indicating that the LP playback mode (the SP playback mode under the standard playback state and the LP tape playback mode under the double speed playback state have the same running speed of the magnetic tape). The playback mode signal Sc indicating that the soft tape playback mode is performed under the standard playback state from the terminal 28, and the SP playback mode under the double speed playback state from the terminal 29 are assumed. One of a reproduction mode signal Sd representing the reproduction mode signal Se representing from the terminal 30 and a reproduction mode signal Se representing that the soft tape reproduction mode under the double speed reproduction state is taken is supplied from the terminal 30. Then, in the data selector 25, in accordance with the reproduction mode signals Sa to Se, the data Da for the LP reproduction mode from the data supply unit 31 under the standard reproduction state and the data Da under the standard reproduction state Data Db for LP playback mode under SP playback mode and 2x speed playback mode, Data Dc for soft tape playback mode under standard playback mode, SP playback mode under 2x speed playback mode Dd for soft tape playback mode under double speed playback
Are respectively selected, and the selected data is used as the data Dx to be supplied to the pulse generator 23. Therefore, the pulse signal Px
Has a pulse width corresponding to any of the data Da to De from the data supply unit 31.

The pulse signal Px obtained from the pulse generator 23 is supplied to the counter 32. The counter 32 is also supplied with a clock pulse CL.The counter 32 receives the clock pulse CL at the trailing edge of the pulse signal Px every time the pulse signal Px arrives in each cycle of the rectangular wave signal FGI supplied to the pulse generator 23.
Clock pulse for a predetermined period from the start of counting to the point in time after the end of each cycle of the square wave signal Fgi.
The counting of CL is continued, and thereafter, the count value is returned to zero prior to the trailing edge of the next pulse signal Px, and the count output signal Cx representing the count value is supplied to the ramp voltage generator 33 during that time.
To supply. The ramp voltage generator 33 generates a ramp voltage VL whose level changes in accordance with a change in the count value of the counter 32, based on the count output signal Cx, and supplies the ramp voltage VL to the sample and hold section.

On the other hand, the rectangular wave signal FGi obtained from the waveform shaping unit 22 is also supplied to the sampling pulse forming unit 35, and the sampling pulse forming unit 35 outputs the sampling pulse Ps synchronized with the end point of each cycle of the rectangular wave signal FGi. And supplies it to the sample and hold unit 34. Thereby,
In the sample and hold section 34, the gradient voltage generation section 33
The sample and hold corresponding to the sampling pulse Ps for the ramp voltage VL from the sample and hold unit 34 is performed, and the sample and hold unit 34 outputs the square wave signal FG obtained from the waveform shaping unit 22.
In each cycle of i, the rectangular wave signal FGi at the ramp voltage VL
The control voltage CVx formed by sampling and holding the level at the end of the cycle is obtained.
That is, a period in which the counter 32 counts the clock pulse CL following the trailing edge of the pulse signal Px is a measurement period in which measurement is performed for each cycle of the rectangular wave signal FGi. A control voltage CVx corresponding to the measurement result of each cycle of the obtained rectangular wave signal FGi is formed.

The control voltage CVx from the sample-and-hold unit 34 is combined with the control voltage CVt from the terminal 37 in the adder 36, for example, according to the tracking state of the rotating magnetic heads 10 and 11 on the magnetic tape Tr. It is supplied to the drive unit 38. Then, the motor drive unit 38 forms a drive signal Sm based on the control voltages CVx and CVt, supplies it to the capstan motor 14, and controls the rotation speed of the capstan motor 14 according to the control voltages CVx and CVt. I do. As a result, in the rotation speed control of the capstan motor 14 according to the control voltage CVx, in the sample and hold unit 34, a predetermined level of the gradient voltage VL from the gradient voltage generation unit 33 is sampled. Pulse forming unit
Capstan motor 14 so that it is sampled and held by sampling pulse Ps from 35.
Is controlled.

Under these circumstances, when the LP reproduction mode is set in the standard reproduction state in the reproduction system, the rectangular wave signal FGi is output when the rotation speed of the capstan motor 14 is appropriate.
Has a period consisting of a period Ta as shown in FIG. 5A, and the pulse signal Px changes in accordance with the data Da, as shown in FIG. Have a pulse width Tb shorter than the period Ta. Then, in the counter 32, the count of the clock pulse CL is performed in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Tb, and the ramp voltage VL formed based on the count output signal Cx from the counter 32. Is obtained as shown in FIG. 5C as having a level that increases linearly in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Tb. At the same time, the sampling pulse Ps is changed into a square wave signal as shown in FIG. 5D.
Obtained in synchronization with the end of the cycle consisting of the period Ta of FGi,
The control voltage CVx is obtained by sampling and holding the level of the ramp voltage VL shown in FIG. 5C in accordance with the sampling pulse Ps shown in FIG. 5D.

On the other hand, in the playback system, the SP playback mode under the standard playback state, or the playback under the double speed playback state
When the LP playback mode is set, the traveling speed of the magnetic tape Tr is doubled as compared with the case where the LP playback mode is set in the standard playback state.
In the state where the rotation speed is appropriate, the rectangular wave signal FGi has a period consisting of a period Ta / 2 as shown in FIG. 5E, and the pulse signal Px is changed according to the data Db. As shown in FIG. F, the pulse width has a pulse width Tc shorter than a period Ta / 2 forming the period of the rectangular wave signal FFi. Then, in the counter 32, the clock pulse in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Tc
The counting of CL is performed, and the ramp voltage VL formed based on the count output signal Cx from the counter 32 is changed from the trailing edge of the pulse signal Px having the pulse width Tc as shown in FIG. 5G. It is obtained as having a level that increases linearly during the measurement period Tt. At the same time, as shown in FIG. 5H, a sampling pulse Ps is obtained in synchronization with the end point of the cycle consisting of the period Ta / 2 of the rectangular wave signal FFi, and the control voltage CVx is obtained as shown in FIG. Is obtained by being sampled and held in accordance with the sampling pulse Ps shown in FIG. 5H.

Next, when the playback system is set to the soft tape playback mode under the standard playback state, the magnetic tape Tr is used.
Is three times higher than in the case where the LP playback mode is set in the standard playback state, the rectangular wave signal FG is output when the rotation speed of the capstan motor 14 is appropriate.
i has a period consisting of a period Ta / 3 as shown in FIG. 5I, and the pulse signal Px is changed according to the data Dc as shown in FIG. It has a pulse width Td shorter than the period Ta / 3 forming the period of FGi. Then, the counter 32 counts the clock pulse CL in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Td, and the ramp voltage VL formed based on the count output signal Cx from the counter 32. Is obtained as shown in FIG. 5K as having a level that increases linearly in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Td. At the same time, as shown in FIG. 5L, a sampling pulse Ps is obtained in synchronization with the end of the period consisting of the period Ta / 3 of the rectangular wave signal FFi, and the control voltage CVx is obtained as shown in FIG. 5L corresponds to the sampling pulse Ps shown in FIG. 5L.
Is obtained by being sampled and held in accordance with.

Also, when the playback system is in the SP playback mode under the double speed playback state, the running speed of the magnetic tape Tr is lower than in the LP playback mode under the standard playback state. When the rotation speed of the capstan motor 14 is proper, the rectangular wave signal FGi has a period consisting of a period Ta / 4 as shown in FIG. 6A. The signal Px is changed to the sixth signal according to the data Dd.
As shown in FIG. B, the pulse width Te is shorter than the period Ta / 4 forming the period of the rectangular wave signal FFi. Then, in the counter 32, the clock pulse CL in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Te
And the ramp voltage VL formed based on the count output signal Cx from the counter 32 is measured from the trailing edge of the pulse signal Px having the pulse width Te as shown in FIG. 6C. It is obtained as having a level that increases linearly in the period Tt. In addition, the sampling pulse
As shown in FIG. 6D, Ps is obtained in synchronization with the end of the cycle consisting of the period Ta / 4 of the rectangular wave signal FFi, and the control voltage CVx is obtained by the ramp voltage VL shown in FIG. 6C. The level of
It is obtained by being sampled and held according to the sampling pulse Ps shown in FIG. 6D.

Further, when a soft tape playback mode under a double speed playback state is set in the playback system, a magnetic tape
Since the running speed of the Tr is six times that in the case where the LP playback mode is set in the standard playback state, the rectangular wave signal is output when the rotation speed of the capstan motor 14 is appropriate.
FGi has a period consisting of a period Ta / 6 as shown in FIG. 6E, and the pulse signal Px is changed according to the data De as shown in FIG. It has a pulse width Tf shorter than the period Ta / 6 forming the period of FGi. Then, the counter 32 counts the clock pulse CL in the measurement period Tt from the trailing edge of the pulse signal Px having the pulse width Tf, and the ramp voltage VL formed based on the count output signal Cx from the counter 32. However, FIG.
As shown in the figure, the pulse signal Px having the pulse width Tf is obtained as having a level that increases linearly in the measurement period Tt from the trailing edge of the pulse signal Px. At the same time, as shown in FIG. 6H, the sampling pulse Ps is obtained in synchronization with the end point of the period consisting of the period Ta / 6 of the rectangular wave signal FGi, and the control voltage CVx is obtained as shown in FIG. The slope voltage VL shown in
Is the sampling pulse shown in FIG. 6H.
It is obtained by sampling and holding according to Ps.

D Problems to be Solved by the Invention As described above, in the rotation speed servo control of the capstan motor using the conventionally proposed capstan motor speed control circuit, the SP playback mode under the standard playback state, LP playback mode and soft tape playback mode,
In addition, SP playback mode under 2x speed playback state, LP
When the playback mode and the soft tape playback mode are selectively selected, the ratio of the measurement period to the period of the square wave signal FGI, which is assumed to have a frequency corresponding to the rotation speed of the capstan motor 14, is determined by the running speed of the magnetic tape. Becomes smaller as the rotation speed of the capstan motor 14 becomes slower, so that the rectangular wave signal becomes smaller.
The measurement accuracy for the period of FGi will be reduced. On the other hand, since the rotation fluctuation of the capstan motor 14 generally increases as the rotation speed decreases, the reproduction mode in which the rotation speed of the capstan motor 14 is relatively low is taken. In this case, the speed servo control is performed on the capstan motor 14 whose rotation fluctuation is large under the condition that the measurement accuracy with respect to the period of the rectangular wave signal FGi is reduced. Is controlled under an unstable servo control system.

Further, in the conventionally proposed capstan motor speed control circuit as described above, a plurality of types for setting the pulse signal Px from the pulse generation unit 23 to have a pulse width corresponding to each reproduction mode, For example, five types of data Da to De
And a data selector 25 for selecting a plurality of types of data from the data supply unit 31 in accordance with the reproduction mode and supplying the selected data to the pulse generation unit 23. And the circuit scale becomes large.

In view of such a point, the present invention provides each of a plurality of reproduction modes for reproducing information from a tape on which information is recorded under each of a plurality of recording modes in which information is recorded at different recording next tape running speeds. Of the signal having a frequency corresponding to the rotation speed of the capstan motor provided in an information reproducing system capable of taking at least two different tape running speeds during reproduction. And the rotation speed of the capstan motor is controlled by a control signal formed based on the measurement result. Even when the rotation speed of the capstan motor is relatively slow over a wide range, the rotation speed of the capstan motor Control can be performed with a stable servo control system, moreover, an object of the invention to provide a capstan motor speed control device so as not accompanied complication or circuit scale enlargement of the circuit configuration.

E Means for Solving the Problems In order to achieve the above object, a capstan motor speed control device according to the present invention provides a capstan motor speed control device in each of a plurality of recording modes in which information is recorded at different recording tape running speeds. Each of a plurality of reproduction modes for reproducing information from a tape on which information is recorded can be set at different tape running speeds during reproduction. A motor speed detector that obtains a speed detection signal having a predetermined frequency, a clock pulse, and a speed detection signal obtained from the motor speed detector. The clock pulse count value from the start of each cycle of the speed detection signal is a predetermined value. A time detection unit for detecting a time when the value becomes a value, a clock pulse and an output signal from the time detection unit are supplied and detected by the time detection unit. A voltage forming section for forming a level change voltage for changing a level according to a clock pulse count value from a time point, and a sample and hold output at the end of each cycle of a speed detection signal for the level change voltage obtained from the voltage forming section A speed control signal forming section for obtaining a speed control voltage, and a motor drive for controlling the rotation speed of the capstan motor by performing drive control of the capstan motor based on the speed control voltage obtained from the speed control signal forming section In addition to the department,
The speed detection signal supplied to the time detection unit has a different frequency according to the tape running speed during reproduction.
And a second signal frequency control unit that causes the clock pulse supplied to the time detection unit and the voltage forming unit to have a different frequency according to the reproduction mode. You.

F Function In the capstan motor speed control device according to the present invention configured as described above, the first signal frequency control unit that makes the speed detection signal have a different frequency according to the tape running speed during reproduction. And a second signal frequency control unit that makes the clock pulse have a different frequency in accordance with the reproduction mode, so that, for example, the SP reproduction mode and the LP in the standard reproduction state as described above are provided. When the playback mode and the soft tape playback mode are applied to the information playback system in which the SP playback mode, the LP playback mode, and the soft tape playback mode under the double speed playback state are selectively used, each playback is performed. In this mode, the measurement accuracy with respect to the period of the speed detection signal is maintained substantially constant regardless of the change in the rotation speed of the capstan motor. Even if the reproduction mode the rotational speed of the capstan motor is a relatively slow is taken, so that the rotational speed of the capstan motor is controlled under a stable servo control system. Further, a data supply unit for supplying a plurality of types of data for setting a pulse width provided in the conventionally proposed capstan motor speed control circuit as described above, and a plurality of types of data from the data supply unit are reproduced. It is not necessary to provide a data selector or the like that selects according to the mode, so that the circuit configuration is not complicated or the circuit size is not increased.

G. Embodiment G-1 Configuration and Operation (FIGS. 1 to 3) FIG. 1 shows an example of a capstan motor speed control device according to the present invention, and such an example is shown in FIG. Of the present invention is applied to a reproduction system in an R-DAT system provided with a signal reading mechanism section.

In this example, the capstan motor 14 obtained from the frequency generator 21 provided in the capstan motor 14 is used.
Signals FGs having a frequency corresponding to the rotation speed of
Is shaped into a signal having a rectangular wave in the waveform shaping unit 22, and a rectangular wave signal FGi as a speed detection signal having a frequency corresponding to the rotation speed of the capstan motor 14 is obtained from the waveform shaping unit 22. It is supplied to the peripheral part 41. The frequency divider 41 is also supplied with the deviation between the reproduction state signal Sn indicating that the standard reproduction state is taken from the terminal 42 and the reproduction state signal St representing that the double speed reproduction state is taken from the terminal 43. When the reproducing state signal Sn is supplied from the terminal 42, the frequency dividing section 41 does not divide the rectangular wave signal FGi,
It is sent out as it is as a rectangular wave signal FFGi, and the pulse generator 44
When the reproduction state signal St is supplied from the terminal 43, the rectangular wave signal FGi is frequency-divided by half to obtain the rectangular wave signal FF.
Gi and supplies it to the pulse generator 44.

On the other hand, a clock pulse with frequency f ₀ from terminal 24
CL is supplied to the frequency divider 45. The frequency divider 45 includes a playback mode signal Sx indicating that the LP playback mode from the terminal 46 is to be taken, a playback mode signal Sy representing that the SP playback mode is to be taken from the terminal 47, and software from the terminal 48. One of the playback mode signals Sz indicating that the tape playback mode is set is supplied.
When the reproduction mode signal Sx from is supplied, as a clock pulse CCL having a frequency f _0/3 and 1/3 frequency-divided clock pulses CL, The playback mode signal Sy from the terminal 47
There when it is supplied, as a clock pulse CCL having a frequency 2f _0/3 with the clock pulses CL to the circumferential 2/3, further, when the reproduction mode signal Sz from the terminal 48 is supplied, minute clock pulse CL not be circumferential, and the clock pulse CCL stay having a frequency f _0. And
The clock pulse CC obtained from the frequency divider 45 in this way
L is supplied to the pulse generator 44.

In the pulse generating unit 44, counting of the clock pulse CCL from the frequency dividing unit 45 is started from the start of each cycle of the rectangular wave signal FFGi from the frequency dividing unit 41 until the counted value reaches a predetermined value. Pulse signal PPx having a leading edge at the start of each cycle of the rectangular wave signal FFGi and having a pulse width corresponding to the measured time.
Is formed. The predetermined value of the count value of the clock pulse CCL in the pulse generation unit 44 is determined based on data Dc supplied from the data supply unit 49 to the pulse generation unit 44. The pulse generator 44 receives the data as described above.
It is provided to generate a pulse signal PPx having a pulse width corresponding to Dc and to set the trailing edge point, and therefore, the clock pulse from the start point of each cycle of the rectangular wave signal FFGi is provided.
This means that a time point detection unit for detecting the time point when the count value of the CCL reaches a predetermined value determined based on the data Dc is formed.

The pulse signal PPx obtained from the pulse generator 44 is supplied to the counter 50. The clock pulse CCL from the frequency divider 45 is also supplied to the counter 50, and the counter 50 receives the pulse signal PPx in each cycle of the rectangular wave signal FFGi supplied to the pulse generator 44, after the pulse signal PPx. At the edge time, counting of the clock pulse CCL is started, and the square wave signal F is started.
The counting of the clock pulses CCL is continued for a predetermined period up to a time point exceeding the end time point of each cycle of FGi, and thereafter,
The count value is returned to zero before the trailing edge of the next pulse signal PPx, and a count output signal CCx representing the count value is supplied to the ramp voltage generator 51 during that time. The gradient voltage generator 51 is configured to generate, based on the count output signal CCx, a gradient voltage VV whose level changes according to a change in the count value of the counter 50.
L is generated and supplied to the sample and hold unit 52.

Further, the rectangular wave signal FFGi obtained from the frequency divider 41 is also supplied to the sampling pulse forming unit 53, where
The pulse forming unit 53 forms a sampling pulse PPs synchronized with the end point of each cycle of the rectangular wave signal FFGi, and supplies it to the sample and hold unit 52. As a result, in the sample-and-hold unit 52, a sample-and-hold operation is performed according to the sampling pulse PPs on the gradient voltage VVL from the gradient voltage generation unit 51, and from the frequency-division unit 41 from the sample-hold unit 52. In each cycle of the obtained square wave signal FFGi, the square wave signal FFGi at the gradient voltage VVL
The control voltage CCVx formed by sampling and holding the level at the end of the cycle is obtained.
That is, the period in which the counter 50 counts the clock pulse CCL following the trailing edge of the pulse signal PPx is a measurement period in which counting is performed for each cycle of the rectangular wave signal FFGi. A control voltage CCVx corresponding to the measurement result of each cycle of the obtained rectangular wave signal FFGi is formed.

The control voltage CCVx from the sample-and-hold unit 52 is combined with a control voltage CVt from the terminal 37 in the adding unit 54, for example, according to the tracking state of the rotating magnetic heads 10 and 11 on the magnetic tape Tr, and It is supplied to the drive unit 55. Then, the motor drive unit 55 forms a drive signal SDm based on the control voltages CCVx and CVt, supplies it to the capstan motor 14, and controls the rotation speed of the capstan motor 14 according to the control voltages CCVx and CVt. I do.
As a result, the capstan motor 14 according to the control voltage CCVx
In the rotation speed control, a predetermined level of the ramp voltage VVL from the ramp voltage generating section 51 is sampled by the sampling pulse PPs from the sampling pulse forming section 53 in the sample and hold section 52. The rotation speed of the capstan motor 14 is controlled so as to be held.

Under such circumstances, in the playback system, in the LP playback mode under the standard playback state, or under the double speed playback state.
When the LP playback mode is set, the clock pulse CCL
There is assumed to have a frequency f _0/3 in as shown in FIG. 2 A, also in the rotational speed proper state of the capstan motor 14, to as the rectangular wave signal FFGi is shown in FIG. 2 B equal to the period of the rectangular wave signal FGi, is to have a period comprising a period Ta, further pulse signal PPx is, the as shown in FIG. 2 C, a total of clock pulses CCL having a frequency f _0/3 It has a pulse width Tg shorter than the period Ta forming the cycle of the rectangular wave signal FFGi, which corresponds to the time until the numerical value becomes a predetermined value according to the data Dc. Then, in the counter 50, the counting of the clock pulse CCL is performed in the measurement period 3Tt from the trailing edge of the pulse signal PPx having the pulse width Tg, and the ramp voltage VVL formed based on the count output signal CCx from the counter 50. But the second
As shown in FIG. D, a pulse signal having a pulse width Tg
It is obtained as having a level that increases linearly in the measurement period 3Tt from the trailing edge of PPx. At the same time, as shown in FIG. 2E, a sampling pulse PPs is obtained in synchronization with the end point of the frequency consisting of the period Ta of the rectangular wave signal FFGi, and the control voltage CCVx is shown in FIG. The level of the ramp voltage VVL is sampled and held in accordance with the sampling pulse PPs shown in FIG. 2E.

On the other hand, in the playback system, the SP playback mode under the standard playback state, or the playback under the double speed playback state
When the SP playback mode is set, the clock pulse CCL
There is assumed to have a frequency 2f _0/3 in as shown in FIG. 2 F, also in the rotational speed proper state of the capstan motor 14, to as the rectangular wave signal FFGi is shown in FIG. 2 G , The period Ta /
2 and a pulse signal P
Px is the as shown in FIG. 2 H, the count value of clock pulses CCL having a frequency 2f _0/3 is assumed to correspond to the time until the predetermined value corresponding to the data Dc, square wave It has a pulse width Th shorter than the period Ta / 2 forming the cycle of the signal FFGi. Then, in the counter 50, the measurement period 3Tt from the trailing edge of the pulse signal PPx having the pulse width Th
/ 2, the count of the clock pulse CCL is performed, and the ramp voltage VVL formed based on the count output signal CCx from the counter 50 becomes the pulse signal PPx having the pulse width Th as shown in FIG. At a measurement period 3Tt / 2 from the trailing edge. At the same time, the sampling pulse PPs
As shown in FIG. J, the control voltage CCVx is obtained in synchronization with the end of the cycle consisting of the period Ta / 2 of the rectangular wave signal FFGi,
The level of the ramp voltage VVL shown in FIG.
Are obtained by sampling and holding according to the sampling pulse PPs shown in FIG.

Further, when a soft tape playback mode under the standard playback state or a soft tape playback mode under the double speed playback state is set in the playback system, the clock pulse CCL is shown in FIG. 2K. to as being, like the clock pulse CL, is to have a frequency f _0, also in the rotational speed proper state of the capstan motor 14, to as the rectangular wave signal FFGi is shown in FIG. 2 L, The pulse signal PPx has a period of Ta / 3, which is 1/3 of the period of the rectangular wave signal FGi.
As shown in FIG. M, a period forming the cycle of the rectangular wave signal FFGi, which corresponds to the time until the count value of the clock pulse CCL having the frequency f ₀ becomes a predetermined value corresponding to the data Dc. It has a pulse width Ti (= Td) shorter than Ta / 3. Then, in the counter 50, the pulse width Ti
The clock pulse CCL is counted in the measurement period Tt from the trailing edge of the pulse signal PPx having the pulse signal PPx, and the ramp voltage VVL is formed based on the count output signal CCx from the counter 50.
As shown in FIG. 2N, the level of the pulse signal PPx having the pulse width Ti has a level that increases linearly in the measurement period Tt from the trailing edge. At the same time, the sampling pulse PPs is obtained in synchronization with the end of the cycle consisting of the period Ta / 3 of the rectangular wave signal FFGi, as shown in FIG. 2O, and the control voltage CCVx is obtained as shown in FIG. Is obtained by being sampled and held in accordance with the sampling pulse PPs shown in FIG. 2O.

Under the above-described operation, when the playback system takes the LP playback mode under the standard playback state or the LP playback mode under the double speed playback state, When the SP playback mode under the standard playback mode or the SP playback mode under the 2x speed playback mode is used, and the soft tape playback mode under the standard playback mode or 2x speed Square wave signal FFGi when soft tape playback mode is taken under playback state
The ratio of the measurement period to the cycle of 3Tt / Ta, (3Tt /
2) / (Ta / 2) = 3Tt / Ta and Tt / 3Ta = 3Tt / Ta, which are equal to each other. Therefore, regardless of the change in the running speed of the magnetic tape according to the reproduction mode, the square wave signal
The measurement accuracy for the period of FFGi is kept constant.

Further, in the example shown in FIG.
The data supplied to 44 for determining the pulse width of the pulse signal PPx is only the data Dc, and therefore, five types of data as required in the capstan motor speed control circuit shown in FIG. The data supply unit 31 that supplies the data Da to De, and the data selector 25 that performs an operation of selecting a plurality of types of data from the data supply unit 31 according to the reproduction mode and supplying the selected data to the pulse generation unit 23 are unnecessary. It is said.

G-2 Modified Example The above-mentioned example is provided with a signal reading mechanism as shown in FIG. 3, and is provided in a SP playback mode, an LP playback mode or a software playback mode in a standard playback state or a double speed playback state. R- which was assumed to be in the tape playback mode
Although it is supposed to be applied to the reproduction system in the DAT system, the capstan motor speed control device according to the present invention is not limited to the application to such a reproduction system, and widely has different tape running speeds during recording. It is assumed that each of a plurality of reproduction modes for reproducing information from a tape on which information is recorded under each of a plurality of recording modes in which information is recorded can have different tape running speeds during reproduction. Various modifications to the above-described example can be configured so as to be applied to the information reproducing system.

H Effects of the Invention As is apparent from the above description, according to the capstan motor speed control device of the present invention, information can be recorded in each of a plurality of recording modes in which information is recorded at different recording tape running speeds. Each of a plurality of reproduction modes for reproducing information from a recorded tape can be set to at least two different tape running speeds at the time of reproduction. Regardless of the change in the rotation speed of the capstan motor in accordance with the reproduction mode, therefore, even when the reproduction mode in which the rotation speed of the capstan motor is set to be relatively slow is adopted, a stable servo control system is also required. And can be controlled with. Further, as provided in a conventionally proposed capstan motor speed control circuit, a data supply unit for supplying a plurality of types of data for pulse width setting, and a plurality of types of data from the data supply unit are set to a reproduction mode. It is not necessary to provide a data selector or the like that selects the information in response to the selection, thereby making it possible to avoid a complicated circuit configuration or an increase in circuit size.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a captan motor speed control device according to the present invention, FIGS. 2A to 2O are waveform diagrams for explaining the operation of the example shown in FIG. 1, and FIG. −DA
FIG. 4 is a schematic configuration diagram showing a signal reading mechanism provided in a reproduction system in the T system, FIG. 4 is a block configuration diagram showing a conventionally proposed captan motor speed control circuit, FIGS. 5A to 5L, and 6A to 6A. H is a waveform diagram for explaining the operation of the captan motor speed control circuit shown in FIG. In the figure, 14 is a captan motor, 21 is a frequency generator, 22 is a waveform shaping unit, 41 and 45 are frequency dividers, 44 is a pulse generator, 49
Is a data supply unit, 50 is a counter, 51 is a gradient voltage generation unit,
52 is a sample and hold unit, 53 is a sampling pulse forming unit, and 55 is a motor drive unit.

Claims (1)

(57) [Claims] 1. A plurality of reproduction modes for reproducing information from a tape on which information has been recorded under each of a plurality of recording modes in which information is recorded at different recording tape running speeds. A motor speed detection unit for obtaining a speed detection signal having a frequency corresponding to the rotation speed of a capstan motor in the information reproduction system, wherein the clock speed and A time detection unit that receives the speed detection signal obtained from the motor speed detection unit and detects a time point at which a clock pulse count value from a start time of each cycle of the speed detection signal reaches a predetermined value; And an output signal from the time point detection unit is supplied, and the clock signal is counted according to the clock pulse count value from the time point detected by the time point detection unit. A voltage forming unit for forming a level change voltage for changing a level, and obtaining a sample and hold output at the end of each cycle of the speed detection signal for the level change voltage obtained from the voltage forming unit, to obtain a speed control voltage. A speed control signal forming unit for forming the motor; a motor drive unit for controlling the driving of the capstan motor based on the speed control voltage obtained from the speed control signal forming unit to control the rotation speed of the capstan motor; A first signal frequency control unit configured to change the speed detection signal supplied to the time point detection unit to have a different frequency according to the reproduction tape traveling speed; and supplied to the time point detection unit and the voltage formation unit. A second signal frequency control unit that causes the clock pulse to have a different frequency according to the reproduction mode. Capstan motor speed control device.