JPH03187052A - Tape running driving device for friction capstan driving system - Google Patents

Abstract

PURPOSE:To stably operate a tape with high-precision speed control by applying servo to a supply reel motor based on back tension data which are read out from a memory and the supply reel-side tape tension detection output. CONSTITUTION:Rotation of a capstan motor Mc which drives a friction capstan CP is detected, and servo is applied to the motor Mc based on a speed command signal and a rotation detection signal to detect the take-up reel-side tape tension to the capstan CP. Servo is applied to a take-up reel motor Mt so that a certain take-up tension is given to the tape based on the detection output, and the tape tension on the side of a supply reel SR is detected. The tape running speed and back tension data based on the rotation detection output of the motor Mc are stored in a memory 16. Servo is applied to the reel SR based on the back tension from the memory 16 and the tape tension detection output of the side of the supply reel SR, thereby stably running the tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a friction capstan drive type tape running drive device suitable for application to VTRs and the like.

[Claim of the invention]

The present invention detects the rotation of a capstan motor that drives a friction capstan, applies a servo to the capstan motor based on a speed command signal and a rotation detection signal, and applies a servo to the capstan motor that drives the tape on the take-up reel side with respect to the friction capstan. The tension run is detected, and based on the detection output, a servo is applied to the take-up reel motor to give a constant take-up tape tension run to the tape, and the tape tension on the supply reel side is applied to the friction capstan. The back tension data determined according to the tape running speed based on the rotation detection output of the friction capstan motor and the drive current flowing through the capstan motor is stored in a memory, and the back tension data read from the memory and supplied. By applying a servo to the supply reel motor based on the detection output from the reel-side tape tension detector, the tape can be operated stably with high precision speed control regardless of the tape running speed. It has been made possible.

[Conventional technology]

A friction capstan drive type tape recorder (Japanese Unexamined Patent Publication No. 57-105843 , U.S. Patent No. 480
7107 specification, etc.).

Below, with reference to FIG. 9, a conventional friction capstan drive type digital video tape recorder (
The tape running system of a digital VTR will be explained.
SR is a supply reel, and Ms is its drive motor. T
R is a take-up reel, and Mt is its drive motor.
DR is a tape guide drum, which includes a fixed lower drum and a rotating upper drum, although not shown, and the rotating upper drum is provided with a rotating magnetic head. And magnetic tape T
The tape P is guided around the tape guide drum DR so as to be wound diagonally, and the winding is regulated by the guides G 9 and G 1 so that the angle is, for example, approximately 180 degrees.

The CP is a friction capstan and should be avoided from rubber etc.
OMC is a motor that drives this friction capstan CP, which allows the magnetic tape TP to be wound around a portion of the circumference of the capstan CP at a predetermined angle by means of the guides G2 and G3.

Then, the magnetic tape T is fed out from the supply reel SR.
P represents guides G6, G7, supply reel side tension arm TAs, guides G8, G3, tape guide drum OR
, guide G*, CTL magnetic head Hc, guide G2, capstan CP1 guide G3, take-up reel side tension arm TAt, guide 4, and G5, and is taken up by the take-up reel TH.

Note that the tension arms TAs and TAt are for detecting the tape tension run, and are not shown in the drawings.
Each is pulled by a spring, and each is equipped with a tension sensor.

Next, with reference to FIG. 10, a servo system in a tape running system of a conventional friction cab scan type digital VTR will be described. First, a servo system for the motor Me that drives the friction capstan CP will be explained. In response to the tape speed control signal from the input terminal (12), the speed control voltage generation circuit (13) generates a control voltage corresponding to the speed, and this is applied to the level comparator C.
Supplied to Pc.

On the other hand, a frequency generator FG is provided which is connected to a multipolar magnet disc m that rotates with the rotation of the motor Mc and a fixed magnetic head h that opposes the multipolar magnet disc m. The rotation speed detection signal from the reproducing magnetic head h is supplied to the frequency/voltage converter (14b) through the amplifier <'14a), and the output voltage thereof is supplied to the comparator CPc to perform the speed control described above. Voltage and level are compared.

Then, the comparison output is supplied to the motor drive circuit DRc, and a drive current corresponding to the comparison output is applied to the motor Mc.
is supplied to the capstan CP motor M.
c rotates at a circumferential speed (equal to the tape running speed) according to a tape speed control signal supplied to the input terminal (12).

Next, servo circuits for the supply reel motor Ms and take-up reel motor Mt will be explained with reference to FIG. (10) is the winding side control voltage generation circuit,
A changeover switch SW2 whose control voltage is switched in conjunction with a changeover control signal from an input terminal (11) depending on whether the running direction of the magnetic tape TP is positive or negative.
, SWl to the level comparator crt or CSs. Further, the rotation speed detection voltage of the capstan motor Mc from the frequency/voltage converter (14b), that is, the magnetic tape running speed detection voltage [speed control voltage generation circuit (13)
The speed control voltage from
) as an address signal. After the supply-side control voltage corresponding to the tape running speed, which is stored in advance in the memory (16), is read out, it is supplied to the D/A converter (17) and converted into an analog signal. The analog reference tension voltage obtained is supplied to the level comparator CPs or crt through the changeover switch S&41 or SH2.

TSs and TSt are tension sensors of the tension arm TAs 5TAt on the supply side and take-up side in FIG. 9, respectively, and the tape tension detection voltages from these on the supply side and take-up side are supplied to the comparator CPs or CPt. The level is compared with the supply side control voltage from the D/A converter (17), and the comparison output is sent to the drive circuit DRs5DR.
t, and the drive current from this is supplied to the motors old and Mt, which drive the supply reel SR and take-up reel TR, respectively.
is supplied to

Next, the operation of the servo system of the conventional VTR shown in FIG. 1O will be explained with reference to the characteristic curves shown in FIGS. 9 and 11. As shown in FIG. 9, with the friction cab scan CP of the magnetic tape TP as a boundary, the tape tension on the supply reel TR side is Tfs, the tape tension on the take-up reel TR side is Tft, and the magnetic tape TP is transferred by the supply reel motor Ms. Applied tension (bank tension) Tl1IS, take-up reel motor Mt
Let the tension (winding tension) applied to the magnetic tape TP by the above equations be To+t, respectively.

For example, when rapidly forwarding the magnetic tape TP, the take-up reel motor Mt is adjusted so that the tension Tmt applied to the magnetic tape TP by the take-up reel motor Mt is constant, that is, Tmt=Tft (FIG. 11A). A drive current is supplied to.

At this time, the coefficient of friction loss that the magnetic tape TP receives on the capstan CP and supply reel TR side is as follows:
Traveling speed of P (equal to the circumferential speed of capstan CP) v
=v1, v2, ..., K according to the change in vn
” Since it changes as K1, 2, ..., Kn, T
From the relationship fs = K Tms, current is supplied to the supply reel motor Ms so that a back tension Tm5 - Tfs /K such that Tfs becomes constant is given to the magnetic tape TP (Fig. 11A), where , Tms=
From the relationship with Tfs/, tape running speed V=V1, V2
, v3, . . . , the supply side control voltage (voltage obtained by dividing the coefficient K = 1, K2, ", Kn) corresponding to the address of the tape running speed detection voltage corresponding to vn, The memory mentioned above (16
), read it out according to the tape running speed, and input it to the D/A converter (17) and selector switch S-
1 to the comparator CPs.

・However, the friction loss coefficient mentioned above does not apply to magnetic tape TP.
It varies greatly depending on not only the running speed but also temperature, humidity, etc. Therefore, each running speed v=v of the magnetic tape TP
1, v2, ..., vn, the tension T applied to the magnetic tape TP by the supply reel motor Ms
As shown in FIG. 11B, ms is determined by coefficients depending on changes in temperature, humidity, etc., +Δ, and −ΔK, respectively, as follows: Tm5=Tfs/K Tags=Tfs'/( K+ΔK〉Trgs=
Therefore, as the tape tensions Tfs and Tft on both sides of the capstan CP in the magnetic tape TP are different, positive and negative loads are applied to the capstan motor Mc accordingly. In order to drive the magnetic tape TP even under such bad conditions, the capstan CP must be
In particular, it is necessary to increase the friction coefficient of the peripheral surface to provide a large margin for the tape driving force.

Digital V with conventional friction capstan drive method and conventional friction capstan drive system
In TR (see Figure 9), as shown in Figure 12A,
The circumferential speed of the drive motor Mc of the friction capstan CP is the circumferential speed of the drive motors Ms and Mt of the reels SR and TR (varies depending on the size of the cassette tape used, i.e. whether it is large, medium or small). much higher than. This figure 12A shows the capstan CP versus time.
and the relationship between the circumferential speeds of the reel motors Ms and Mt, that is, their rotational speeds, and the slope thereof is equivalent to the acceleration.

Therefore, when the magnetic tape TP is running at high speed, the maximum acceleration of the capstan motor Mc (when the cassette tape is small)
When you accelerate or decelerate the peripheral speed of the capstan motor,
Since the angle of the tension arms TAs and TAt exceeds the normal operating angle range, the reel motor MsSML
The tension applied to the magnetic tape TP due to the rotation of the magnetic tape TP cannot be controlled.

FIG. 12B shows the circumferential speeds of the supply reel motor Ms and the take-up reel TR when the tape winding diameter of the take-up reel TR of the cassette tape of large, medium, and small cassettes changes from minimum to intermediate to maximum. This shows the characteristics of the smaller maximum circumferential acceleration.

As can be easily seen from the maximum circumferential acceleration characteristics in FIG. Therefore, in digital VTRs that use conventional cassette tapes with different sizes of large, medium, and small cassettes, the size of the cassette tape loaded in the VTR is detected, and the cap The circumferential speed of the stun drive motor Mc is set so that it does not exceed the rotational acceleration of the reel drive motors Ms and ML.
The peripheral speed was determined.

As is clear from this FIG. 12B, the reel motor Ms
, Mt varies greatly depending on the winding diameter of the magnetic tape TPO wound on the reels SR and TR, even for cassette tapes of the same size. Compared to the minimum diameter and maximum diameter for the reels SR and TR, the characteristics are improved at the intermediate diameter, but since the circumferential speed of the capstan motor Mc is constant, for example, in the case of a medium-force set cassette tape. , the areas indicated by crosshatches are useless characteristics for reel motors Ms and Mt.

Speed-following (U-side - Digital V of conventional friction capstan drive system)
Tension arm TA (TAs, TAt) used in TR (see Fig. 9) rotates around a fulcrum CT as shown in Fig. 13, but the operating angle of arm TA is θ4 and θ2, respectively. , θ3, θ4, . . . , θn, the elastic force of the spring SP that provides the arm biasing force is proportional to its operating angle, as shown in FIG. Then, when the operating angle of the arm is, for example, θ3 during playback of the digital VTR, that is, when the magnetic tape is running in the forward direction, the reel motor Ms at a certain loop gain (Go) of the servo loop for the reel motors Ms and Mt. , M
The accuracy that t gives to the magnetic tape TP is θ3± Δθ
, when the tension value is g, ±Δg, the loop gain G is used to increase the accuracy of the tension.

need to be raised as much as possible. However, the higher the loop gain Go is raised, the less phase margin there is, causing the problem that (2) becomes unstable.

On the other hand, as in the tension arm AT shown in FIG. 15, one end of the spring SP is attached to the middle of the arm AT, and the other end is attached to a part of the sector gear GR. It has been proposed in the past that the shaft be driven by a stem motor M via a small gear GR2 that meshes with the shaft. In this way, the operating angle of the arm TA in each mode of running in the reverse direction, running in the forward direction, and stopping is rotated to both sides around a point in the center of θ1 to θn, and the operating angle of the arm TA is determined by the elastic force of the spring SP. As shown in FIG. 16, the characteristics of the change are also broader compared to FIG. 14. Therefore, in the servo system for the reel motor MsSMt, the first
Similarly to Figure 4, the tension accuracy applied to the magnetic tape is ±
Assuming that the loop gain falls within the range of Δθ, the loop gain should be gl ±Δg1, and although the tension accuracy is improved compared to the case shown in Fig. 14, the design emphasizes system stability by lowering the loop gain. I caution that it is also possible to make a choice.

However, if the loop gain is simply lowered to G, -'G2, the first
As shown in Fig. 7, the servo band also decreases from SB to SB2, and although the stability of the system improves, the transient response deteriorates.

[Problem to be solved by the invention]

As described in the above-mentioned prior art (1), when the magnetic tape TP is fast forwarded by the friction capstan drive type tape running drive device, for example, when the magnetic tape TP is fast-forwarded, the force applied to the magnetic tape TP by the take-up reel motor elbow is The back tension Tmt is constant, that is, Tmt
A drive current is supplied to the take-up reel motor Mt so that =Tft (FIG. 11A).

At this time, the coefficient of the total friction loss that the magnetic tape TP receives at the capstan CP and the supply reel motor includes the running speed of the magnetic tape TP v=v1, v2,...
According to the change in vn, K= changes to 1sK2, -1Kn, so from the relationship Tfs = K - Tms, Tf
Tension Tm5-Tfs /K such that s becomes constant
Current is supplied to the supply reel motor so that the voltage is applied to the magnetic tape TP (FIG. 11A).

Therefore, from the relationship T+ns = Tfs/, the reference digital tension voltage (Tfs is used as a coefficient) corresponding to the address of the tape running speed detection voltage corresponding to the tape running speed v=v1, v2, v3, ..., vn. = to,,K2,・
.
7) and the changeover switch SW, and is supplied to the comparators CPs and CPt through the switch SW.

However, the above-mentioned friction loss coefficient varies greatly depending not only on the running speed of the magnetic tape TP but also on temperature, humidity, and the like. Therefore, each running speed v=v2 of the magnetic tape TP
, v2, ..., vn, the supply reel motor M
The tension Tm applied to the magnetic tape TP by s
As shown in FIG. 11B, s is Tm5-Tfs/K Tms-Tfs'/ according to coefficients depending on changes in temperature, humidity, etc., +Δ, and -ΔK, respectively. (K + ΔK) Tms=Tfs"8 to 1 ΔK) Therefore, the tape tension Tfs on both sides of the capstan CP at the magnetic tape ↑P.

It is important to note that the Tfts are not equal and that positive and negative loads are applied to the capstan motor MsCP accordingly.

In order to drive the magnetic tape TP even under such bad conditions, it is necessary to increase the coefficient of friction of the capstan CP, especially its circumferential surface, to provide a large margin for the tape driving force.

In view of this, the present invention solves the drawbacks of the conventional technology (1) described above, and provides a friction capstan that can operate the tape stably with highly accurate speed control regardless of the tape running speed. This paper attempts to propose a drive-type tape running drive device.

[Means to solve the problem]

The present invention includes a capstan motor Mc that drives the friction capstan CP, a rotation detector FG that detects the rotation of the capstan motor Mc, and a cap A capstan motor servo circuit that controls the rotation of the stun motor Mc, a take-up reel motor Mt, and a take-up reel side tape tension detector TSt that detects the tape tension on the take-up reel side with respect to the friction capstan CP; Based on the detection output from the take-up reel side tape tension detector TSt, the tape TP
A take-up motor servo circuit that controls the rotation of the take-up reel motor, the supply reel motor Ms, and the friction capstan CP control the tape tension on the supply reel side so as to give a constant take-up tape tension to the take-up reel motor. A memory ( 17 )and.

Back tension data read from the memory (17) and supply reel side tape tension detector TSs
The supply reel motor servo circuit controls the rotation of the supply reel motor Ms based on the detection output from the supply reel motor Ms.

[Effect]

According to the present invention, the capstan servo circuit controls the rotation of the capstan motor Mc based on the speed command signal and the rotation detection signal from the rotation detector FG that detects the rotation of the capstan motor Me. The take-up reel motor servo circuit causes the friction capstan CP to take up a certain amount of the tape TP based on the detection output from the take-up reel side tape tension detector TSt that detects the tape tension on the take-up reel side. The rotation of the take-up reel motor is controlled to provide tape tension. With respect to the friction capstan CP, back tension is determined based on the detection output from the supply reel side tape tension detector TSs that detects the tape tension on the supply reel side, and according to the tape running speed and the drive current flowing to the capstan motor Mc. The data is stored in the memory (17), and the supply reel motor servo circuit determines whether the supply reel is Controls the rotation of motor Ms.

〔Example〕

Hereinafter, a servo system for a capstan motor as an embodiment (1) will be explained with reference to FIG. In FIG. 1, parts corresponding to those in FIG. 10 are given the same reference numerals. (10) is a control voltage generation circuit on the winding side, and the control voltage from this circuit is switched in conjunction with the switching control signal from the input terminal (11) depending on whether the magnetic tape TP is running in the forward or reverse direction. Level comparator CPt or C
3t is supplied.

Further, the rotation speed detection voltage of the capstan motor Me from the frequency/voltage converter (14b), that is, the magnetic tape running speed detection voltage (the speed control voltage from the speed control voltage generation circuit (13) is also possible) is A After being supplied to the /D converter (15) and converted into a digital signal, it is supplied to the memory (16) as an address signal, and tension control according to the tape running speed is stored in the memory (16) in advance. After the voltage is read out, it is supplied to the D/A conversion @ (17) and converted into an analog signal, and the obtained supply side control voltage is passed through the changeover switch SW or Sn2 to the comparator CPs.
Or supplied to CPt.

TSs and TSt are the supply side tension (tension) sensor and take-up side tension sensor of the tension arms TAs and TAt in FIG. CPs or CPt is supplied to the D/A converter (
17), the comparison output is supplied to the drive circuit DRs or DRt, and the drive current from this is supplied to the supply or rewind reel motors Ms, Mt, respectively.

The above configuration is similar to that shown in FIG. 10 described above. Now, in this embodiment, with the capstan CP as the boundary, the tape tension Tf on the supply and take-up reel sides,
, Tf 2 is due to a change in the load on the capstan CP, and this change in the load on the capstan CP is detected as a change in the drive current of the capstan motor Mc.

FIG. 2A shows the relationship between changes in the balance of tape tensions Tfs and Tft and the drive current for the capstan motor Mc. That is, when Tfs-Tft, the motor Mc is in a no-load state, the drive current is O, and T
As fs becomes larger than Tft, the absolute value of the drive current increases in the positive direction, and as Tfs becomes smaller than Tft, the absolute value of the drive current increases in the negative direction.

Therefore, a current detection circuit (19) is provided to detect the drive current supplied to the capstan motor Mc, and the drive current is detected from the drive amplifier DRc. Then, the drive current detection signal is supplied to an integrating circuit (20) for integration, then supplied to an A/D converter (21) to be converted into a digital signal, and then sent to the memory (16) as an address signal.
16).

Next, the operation of the servo system of the embodiment shown in FIG. 1 will be explained with reference to FIGS. 2, 3, and 9. The tape running system of this embodiment is similar to the conventional example shown in FIG. 9, and as described above, the tape tension on the supply reel TR side of the friction capsun CP is Tfs, the tape tension on the take-up reel TR side is Tft, Supply reel motor Ms
The tension applied to the magnetic tape TP by Tl
Magnetic tape T by l1s take-up reel motor Mt
Let Tms be the tension applied to P, respectively. Incidentally, while the magnetic tape TP is running, the tape tensions Tfs and Tft on both sides of the capstan CP are made equal to each other.

For example, when the magnetic tape TP is fast-forwarded, the tension T+at applied to the magnetic tape TP by the take-up reel motor is constant, that is, TIIt=Tft.
A drive current is supplied to the take-up reel motor Mt so that (FIG. 11A).

At this time, the coefficient of the total friction loss that the magnetic tape TP receives on the capstan CP and supply reel TR side includes the running speed of the magnetic tape TP V ''' Vl , V2 , . . .
..., Vn changes and the drive current of the capstan motor Mc changes K=1, K2, ..., Kn, so from the relationship Tfs = K 4n + s, Tfs becomes constant. The bank tension Tms (FIG. 2A-D) is stored in advance in the memory (16), and is controlled by an address signal corresponding to the running speed of the magnetic tape TP and the driving current i of the capstan motor (FIG. 2A). The back tension Tms is read out and the D/A converter (
17) and is converted into an analog signal, it is sent to the level comparator C through the changeover switch SW or S-2.
Ps or CPt, tension detector TSs,
It is compared with the detection output from TSt, and the comparison output is supplied to the drive amplifier DRs or DRt, and a drive current is supplied to the reel motor Mt.

In FIG. 2C, the drive current i of the capstan motor Mr is, for example, i. The figure shows a state in which when the back tension T+++s changes from io+Δi to io−Δi around , the back tension T+++s curves from A to D in FIG. 2B are moved accordingly.

FIG. 3 shows the winding tension Tmt applied to the magnetic tape TP by the winding reel motor ht as the running speed of the magnetic tape TPO increases over time.
initially rises rapidly and then becomes constant; on the other hand, the bank tension Tms applied to the magnetic tape TP by the supply reel motor Ms is caused by the capstan motor M
Curves A, B, and C according to the driving current shown in c show a stepwise change. In FIG. 3, the horizontal axis represents time, and the vertical axis represents tape running speed and supply reel side tape tension Tfs. Also, Tfs I, T
fs 2, Tfs s % . . . , Tfsn indicate the tape tensions on the supply reel side when the tape running speeds are V1, V2, V3, "', and vmax, respectively.

The servo system of this embodiment will be explained below with reference to FIG. Winding side and supply side tension detector TSs,
The tension detection output from TSt is connected to each bipolar limiter SL.
s, SLt, and are supplied to an adder (22) for addition, and the summed output is supplied to a subtracter (25) through an amplifier (23) and an on-off switch (24), and then a frequency/voltage converter. (25), and the subtracted output is supplied to the level comparator CPc.

The other configurations are the same as in FIG. 1.

Next, the operation of the embodiment shown in FIG. 4 will be explained with reference also to FIGS. 5 and 6. The tape running system of the VTR in this embodiment is the same as the conventional example shown in FIG. 9, but the tension arms TAt, TAs on the take-up side and the supply side have rotation angles of ±θ as shown in FIG. If the rotation angle is within the range of ±θX (however, θ, θ
(X is a positive number and θ>θX), the limiters SLs and SLt do not operate; when this is exceeded, the limiters SLs and SLt operate, and the tension detectors TSs and TS
The detection output from these limiters SLs and SLt
After being sorted by , it is supplied to the adder (22).

Further, the on/off switch (25) is turned off during normal playback and turned on during fast forward and rewind playback. As shown in FIG. 6, as time passes, the circumferential speed of the supply side reel motor Ms increases as shown by Vr during normal playback, but during fast forward and rewind playback, the circumferential speed of the supply side reel motor Ms increases as shown in Vr. When the circumferential velocity of the capstan CP up to
At t2, the circumferential velocity exceeds Vc, and until it reaches Vr, its increase is suppressed as at Vc2 by the action of the main ivy SLs and SLt.

In addition, the angle error can be determined by slicing the small level and adjusting the arm TA.
The range of ±θX may be set as a dead zone for the operating angle ±θ. The angle error may be configured with a differentiator so as to provide feedback only during transient times. Furthermore, it is also possible to turn on the switch and operate only the shuttle mode with large transient changes, and turn off the other motors.

With the above configuration, it is possible to apply damping to transient changes in the capstan motor Mc, and the running speed of the magnetic tape TP is stabilized regardless of the size of the cassette tape or the winding diameter of the tape on the reel. It is possible to perform accurate acceleration/deceleration.

The configuration of this embodiment will be described below with reference to FIG. 7. A tension arm TA (TAs) is used in a friction capsun drive type digital VTR similar to the conventional example shown in FIG.

As shown in FIG. 7, as in the conventional example shown in FIG. 15, TA L> has one end of the spring sp attached to the arm TAs, one end of the TAt, and the other end attached to a part of the sector gear GR. The fan-shaped gear GR is configured to be driven by a step motor M via a pinion wheel GR2 that meshes with the fan-shaped gear GR. The operating angle of arm TA in each mode of running in the reverse direction, running in the forward direction, and stopping is between θ and θ.
The characteristic of the change in the elastic force of the spring sp is similar to that of FIG. 16, and is broader than that of FIG. 14. For this reason, in the servo system for the reel motor,
As shown in Fig. 14, if the loop gain is such that the tension accuracy applied to the magnetic tape is within the range of ±Δθ, then
The loop gain is set to gl ±Δg, and the tension accuracy is improved compared to the case of FIG. 14, the loop gain is reduced, and the stability of the system is ensured.

Therefore, by detecting the angles of the take-up reel side and supply side reel tension arms ATs 5ATt, the above-mentioned take-up side and supply side tension detectors TSt and TSs, which detect the tape tension, are respectively amplified and a level comparator CPs is installed. , an amplifier (27) that supplies CPt
will be established. Then, the gain of this amplifier (27) is set to the eighth
As shown in the figure, when the angle error of the winding side and supply side tension arms ATs and ATL is small, it is made small as G2, and when it is large, the gain is made large like G. In Fig. 8, the horizontal axis is the tension arm ATs, the angle error of ATL, and the vertical axis is the amplifier (27
) shows the output of

According to the embodiment shown in FIG. 7, the tension arm AT
Since the gain of the drive amplifier (27) is large in areas where the angular error of s and ATt is large, the servo band can be made sufficiently large, thereby improving responsiveness. By the way, it is possible to form a stable servo loop by ensuring that the phase margin is sufficient.

〔Effect of the invention〕

According to the present invention described above, the rotation of the capstan motor that drives the friction capsun is detected, the servo is applied to the capstan motor based on the speed command signal and the rotation detection signal, and the winding is performed on the friction capsun. The tape tension on the reel side is detected, and based on the detection output, a servo is applied to the take-up reel motor to give a constant take-up tape tension to the tape, and the tape tension on the supply reel side is applied to the friction capsun. is detected, back tension data determined according to the tape running speed based on the rotation detection output of the friction capstan motor and the drive current flowing through the capstan motor is stored in a memory, and the back tension data read from the memory and Based on the detection output from the tape tension detector on the supply reel side,
Since a servo is applied to the supply motor, the tape can be operated stably with highly accurate speed control, regardless of the tape running speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment (servo system) of the present invention, FIG. 2 is an explanatory diagram for explaining the operation of FIG. 1, FIG. 3 is an explanatory diagram for explaining the operation of FIG. Figure 4 shows an example (
5 is an explanatory diagram of the angle of the tension arm to explain the embodiment in FIG. 4, and FIG. 6 is a characteristic curve to explain the embodiment in FIG. 4. 7 is a block diagram showing a part of the embodiment (servo system) of the present invention, FIG. 8 is a curve diagram showing gain characteristics to explain the operation of FIG. 7, and FIG. 9 is a conventional digital A layout diagram showing the tape running system of a VTR, Figure 10 is a conventional digital VTR.
A block diagram showing the servo system of the TR, Figure 11 is the 10th
Characteristic curve diagram for explaining the conventional example servo system shown in the figure, Part 1
2 is a characteristic curve diagram for explaining the operation of the servo system in the conventional example shown in FIG. 11, FIG. 13 is an explanatory diagram for explaining the operation of the tension arm in the conventional example shown in FIG. A characteristic curve diagram for explaining the operation of a conventional tension arm; FIG. 15 is a layout diagram showing a conventional tension arm;
FIG. 16 is a characteristic curve diagram showing the characteristics of the conventional tension arm shown in FIG. 15, and FIG. 17 is a characteristic curve diagram of the conventional tension arm shown in FIG. SR is the supply reel, Ms is the supply reel motor, DRs is the supply side drive circuit, CPs is the supply side level comparator, TSs
is the supply side tension detector, ATs is the supply side tension arm, TR is the take-up reel, elbow is the take-up side motor, DR
t Drive circuit for the winding side motor, crt is the winding side level comparator, TSt is the winding side tension detector, ATs
is the supply tension arm, TP is the magnetic tape, DR is the rotating drum, CP is the friction carburetor, Mc is the capstan motor, FG is the rotation detector, (14b) frequency/voltage converter, DRc is for capstan motor drive. Amplifier, CPc is capstan side level comparator, (16
) is a memory, ATs % AT, AT is a tension arm, sp is a spring, GRI% GR2 is a gear, and M is a step motor. Agent Hidemori Matsukuma (Unprecedented) 1-Heavy Industries Figure 17 Tl5 = T1 declared Figure 3 Implementation Ike 1's sir゛(no-[phase] Figure 4 Tensoyoso arm's seat Figure 5) Lol □ Way! The weight of the example is also shown in Figure 6 - TA Ike 1's 1st turn $ a) - @ Figure 7 OR tape $ 1t 1) 'Ram 71 stone S tape SR4 part 9-1 and TR End of ears Nuri reel cp Capstaso TAs, TAt Teso 1 Tour Mui Shiba Mi's VT/? Tape running thread Figure 9 Figure TO Tape speed tape tit Ishibarai f9'l 71 pillars 11 Figure power set 32 stars - Conventional previous 1-1 Temple name area Figure 12 '4 Dohe Now ↑ Sonotsuso Arm Figure 13 A! 1132 Figure 14 Figure 15 of Tenzosso of Ike 1 Figure 16

Claims (1)

[Claims] A capstan motor that drives a friction capstan; a rotation detector that detects rotation of the capstan motor; A capstan motor servo circuit that controls the rotation of a stun motor, a take-up reel motor, a take-up reel side tape tension detector that detects tape tension on the take-up reel side for the friction capstan, and the take-up reel. a take-up reel motor servo circuit that controls rotation of the take-up reel motor so as to give a constant take-up tape tension to the tape based on the detection output from the side tape tension detector; a supply reel motor; A tape tension detector on the supply reel side detects the tape tension on the supply reel side with respect to the friction capstan, and the tape running speed is determined based on the detection output from the rotation detector and the drive current flowing to the capstan motor. a memory in which back tension data is stored; and a supply reel motor servo that controls rotation of the supply reel motor based on the back tension data read from the memory and a detection output from the supply reel side tape tension detector. 1. A friction capstan drive type tape running drive device comprising a circuit.