JPH0364940B2 - - Google Patents

Description

[Detailed Description of the Invention] In conventionally known tape tension control devices, even if the tape tension is controlled to be constant, especially when accelerating or decelerating the tape speed, the acceleration is not always constant. do not have. If the acceleration is not constant, the following problems may occur.

For example, when a VTR equipped with an editing function is in high-speed search mode, it is necessary to run the tape at high speed in order to shorten the search time. The tape speed is automatically reduced when the tape approaches the search position, and the program is controlled so that the tape automatically stops at the target search position.

FIG. 1 is an example of this stepwise speed control, and this example shows speed control characteristics during deceleration. As in this example, when decelerating in stages from the maximum speed (50 to 60 times the normal speed) to 10x speed, or from 10x speed to 1x speed (steady speed), if the deceleration characteristics are not constant, the deceleration will begin. Variations occur in the time it takes to reach a predetermined double speed.

Therefore, in that case, it is not possible to correctly program the braking force and braking time to be applied to the motor in order to achieve a predetermined double speed. Furthermore, braking force and other factors vary greatly depending on the reel diameter and tape amount used, making the program even more difficult in this case.

In view of these inconveniences, the present invention provides a tape speed control circuit that maintains constant speed characteristics and tape tension during acceleration and deceleration, especially during deceleration, regardless of the reel diameter or tape amount used. It is composed of That is, the present invention dynamically detects the tape winding diameters of the supply reel and take-up reel, the moments of inertia of the tapes themselves of the supply reel and take-up reel, and the moments of inertia of the supply and take-up reels themselves, and uses these detected outputs. By controlling the torque of the reel motor based on the above, the acceleration and tape tension of the tape converge to a predetermined value and become constant when the tape is accelerated or decelerated.

An example of the tape running control circuit according to the present invention will be explained in detail below with reference to the drawings. Since it is determined by the moment of inertia of the reel, in order to control the tape speed, it is necessary to detect the moment of inertia at that point.

Here, the relationship between the moment of inertia of the reel, tape tension, and acceleration is as follows, assuming that the moment of inertia on the tape feeding side is I _S and the moment of inertia on the tape winding side is _IT .

I _S = r _S / α (T _SO + r _S F _S ) ...(1) I _T = r _T / α (T _TO + r _T F _T ) ... (2) Here, r _S , r _T : tape Tape winding diameter α on the supply side and take-up side: Tape acceleration T _SO , T _TO : Initial torque generated in the motor on the tape supply side and take-up side F _S , F _T : Tape tension on the tape supply side and take-up side In this way, if the moments of inertia I _S and _IT at the initial torque T _SO and T _TO are determined, the motor torques T _S and T _T at that time are as follows.

T _S ＝α／r _S・I _S −r _S F _S ……(3) T _T ＝α／r _T・I _T −r _T F _T ……(4) In addition, equations (1) and (2) Regarding the moment of inertia of the reel shown in , the tape acceleration value is more dominant than the tape tension value on the tape supply side, and the tape tension value is more dominant than the tape acceleration value on the tape winding side. Since it is dominant, equations (1) and (2) can be transformed into I _S ≒r _S ／α・T _SO ……(5) I _T ∝a−dF _T ……(6) a=r _T ／αT _TO , b=r _T /α, where r _T and T _TO are the previous measured value and output value.

Even if it is simplified or transformed like
This is not significantly different from (1) and (2). Therefore,
From the moment of inertia and tape winding diameter determined based on equations (5) and (6), configure a control system so that the acceleration and tape tension during acceleration and deceleration, especially during deceleration, converge to their respective set values. be able to.

FIG. 2 shows a specific example for implementing the above-mentioned control operation. 1S is the tape winding diameter r _S on the supply reel side
The output FG _S obtained from the frequency generator attached to the supply reel driving motor (not shown) is supplied from terminal 2 to this detection means, and the output obtained from the timer roller is supplied to this detection means.
TR is supplied through terminal 3. Tape winding diameter r _S
can be obtained from the ratio TR/FG _S of both outputs.

Similarly, 1T is a detection means for detecting the tape winding diameter r _T on the take-up reel side, and the input terminal 4 is supplied with an output FG _T proportional to the rotational speed of the motor for driving the take-up reel. The tape winding diameter r _T is detected from FG _T and the output TR of the timer roller.

Further, 10S and 10T are means for obtaining the torques MT _S and MT _T given to the motors on the supply reel side and take-up reel side, and the tape winding diameters r _S and r _T are means for obtaining the moments of inertia _ITS and I _TT of the tape itself. 11S and 11T. Here, the moment of inertia of the tape I _T
I _T = πγh/2g (r ⁴ − _{r O} ⁴ ) = K (r ⁴ − r _O ⁴ ) ……(7) However, K = πγh/2g = constant g: Gravitational acceleration γ: Tape density h: Tape Width _rO : Since it is given by the diameter of the reel hub, the detection means 11S and 11T are supplied with an output related to the reel hub diameter _rO of the reel used by the husband.

Incidentally, the moment of inertia of the reel itself is detected by means 20 described below.

First, the output TR obtained from the timer roller is supplied to the acceleration α detection means 21. This detection means 21 is composed of a differentiating circuit. Note that the acceleration α can also be determined from the outputs FG _S and FG _T from the frequency generators provided on the supply and take-up reels. The output indicating this acceleration α is the first data on the moment of inertia of the reel on the tape supply side.
is supplied to comparison means 22 and compared with a first set value indicating the moment of inertia of the reel.

The first set value is a reference acceleration value,
This value is prepared in a table provided in the first comparing means 22, and is used as the reference value (first
The output representing the acceleration α is compared with this first set value and output. In this example, the first comparison output is a binary output, and when it is larger than the first set value, the first comparison output becomes "1".

On the other hand, on the supply reel side, means 23 for detecting the tape tension F _S in a portion close to the supply reel is provided. In this example, tape tension F _S is detected by a potentiometer attached to the tension arm on the supply side. This tape tension F _S is supplied to second comparison means 24 and compared with a second set value.

The second setting value is a reference value of the tape tension to be applied to the supply tape when the tape is rewound onto the supply reel. Also, even though it is the tape tension on the supply reel side, the value at the time of rewinding is input as the tape tension value because, as mentioned above, the value of the tape tension on the supply reel side is input when rewinding. This is because it is necessary to use this as data for calculating the moment of inertia of the reel.

A means 25 for detecting the tape tension F _T in a portion close to the reel is also provided on the take-up reel side, and the tape tension is supplied to a third comparison means 26 and compared with a third set value. In this case as well, the reference value of the tape tension near the take-up reel is prepared in the table as the third set value. This tape tension data is the data at the time of tape winding.

These first to third comparison outputs C〓, C _S , C _T are input to predetermined two
One comparison output is selected and two selected comparison outputs are selected.
The two comparison outputs are supplied as data correction signals to up-down counters 30S and 30T for forming the moment of inertia of the reel. one counter 3
0S is to obtain the moment of inertia _ISR of the supply reel, and this includes the first comparison output C〓 regarding the acceleration α when the tape runs from the supply reel to the take-up reel, that is, at the forward time. It is supplied as a data correction signal, and in reverse mode, a second comparison output C _S regarding the tape tension F _S on the supply side is supplied as a data correction signal.

The other counter 30T is used to obtain the moment of inertia I _TR of the reel on the take-up side _.
The third comparison output _CT is supplied as a data correction signal, and the first comparison output
C〓 is supplied.

In this way, since the data correction signals used in the respective counters 30S and 30T are different during forward and reverse times, a switching circuit 2 is provided at the front stage of each counter 30S and 30T.
7 is provided, and the switching signal supplied to the terminal 27a provides the first to third comparison outputs C〓 as described above.
~C _T is selected. As this switching signal, a pulse _ST related to a signal indicating the tape running method is used.

By the way, these counters 30S and 30T are both presettable counters, and the preset values are changed based on data based on the tape winding diameters r _S and r _T , thereby determining the minimum reel value obtained from the tape winding diameters. The moment of inertia of is initially set.

Then, the counters 30S and 30T perform a down-count operation when the level of the first comparison output C〓 is "1", and therefore the acceleration α and the tape tensions F _S and F _T are larger than their respective set values, "0" Therefore, when it is less than the set value, up-count operation is performed, and the second and third comparison outputs C _S ,
In the _{case of C} controlled by.

Note that 31 is an oscillator for the clock CK, and its frequency is approximately several Hz to 10 Hz. In this way, the clock frequency was selected to be low because the counter 30S,
This is because it takes some time for the acceleration α, tape tensions F _S and F _T to be changed to reflect the correction contents of 30T.

The moments of inertia I _SR and I _TR of each reel that can be corrected in this way are combined with the moments of inertia I _ST and I _TT of the tape, and then supplied to the first calculation means 13S and 13T. In other words, the motor torques MT _S and MT _T at forward time are obtained from equations (3) and (4) as follows: MT _S = αI _S /r _S −r _S F _S /n _S ...(8) MT _T = αI _T /r _T −r _T F _T /n _T ...(9) Here, n _S and n _T are given by the tension ratio during forward and reverse (the motor torque during reverse is expressed by equation (8), (9) ), the sign of the second term on the right side of the equation is opposite), in the first calculation means 13S and 13T,
The first term on the right side of equations (8) and (9) is calculated.
The first setting value is used for the acceleration α. In addition, 1
2S and 12T indicate combiners.

Further, the first calculation output is further supplied to second calculation means 14S and 14T, and after adding information on the tape running direction, the entire right side of equations (8) and (9) is processed, The motor torque outputs MTS and _MTT obtained at the respective output terminals 15S and _15T are supplied as torque control signals to each motor. As a result of controlling this motor torque, the detected values of the acceleration α and the pair of tape tensions F _S and F _T are re-compared as described above, and the counters 30S and 30T are set by the next sampling clock CK. The moments of inertia I _SR and I _TR are modified.
This control loop operates until the acceleration α converges to the first set value and the tape tensions F _S and F _T converge to the second and third set values, respectively. Through this series of control operations, the acceleration during acceleration and deceleration of the tape is controlled to be constant, and the tape tension of each reel is controlled to be constant.

As explained above, according to the present invention, when accelerating or decelerating the tape, the acceleration and tape tension of the tape can be kept constant, so especially when decelerating the tape, the braking force and braking time applied to the motor can be programmed correctly. . In addition, even when reels with various diameters are installed, or when the reel diameters differ between the supply side and the take-up side, the moment of inertia of the tape itself on the supply side and the take-up side dynamically changes. Since the moment of inertia is detected and the motor torque is controlled based on these detected outputs, the acceleration and tension of the tape can be kept constant regardless of the diameter of the reel used or the amount of tape used. High program accuracy can be maintained even in difficult situations. Even in this case, the program accuracy is high.

Then, if the count values of the counters 30S and 30T are preset based on the first detected reel winding diameters r _S and r _T as shown in Fig. 2, the count values of the counters 30S and 30T can be converged to the first, second, or third set values. It can save time. Of course, it may be fixed to a certain value without presetting. In this case there is no need to use a presettable counter.

Furthermore, if the amount of information handled by the torque control means 10S, 10T is about 8 bits, the control means 10S, 10T can be replaced with a ROM.

FIG. 3 shows another embodiment of the invention. In this example, the configuration is simplified compared to the case shown in FIG. 2, and the tensions F _S and F _T on the supply side and take-up side are supplied to a switching circuit 40 and are controlled by a signal S _T indicating the tape running direction. selected. That is, the take-up tension F _T is selected in forward mode, and the supply tension F _S is selected in reverse mode.

The selected tape tension F _S or F _T is the first
is supplied to the window comparator 41 of the fifth
setting value (second or third used in Figure 2)
A comparison is made to see if the value of the tape tension F _S or F _T is within a predetermined width around the center (approximately equal to the set value of ). The comparison output is the switching circuit 42
(described later) to an up-down counter 43 that calculates the ratio of the moment of inertia of the take-up reel to the moment of inertia of the supply reel, and a counting operation is performed according to the polarity of the comparison output "1" or "0". controlled. The output of the counter 43 is supplied to an arithmetic circuit 45 that obtains the moments of inertia I _SR and I _TR of each reel.

By the way, when the tape is run in the forward direction and when it is run in the reverse direction, the moment of inertia ratio cannot be calculated correctly unless the comparison output from the first comparator 41 is inverted and supplied to the counter 43. A switching circuit 42 is provided so that the comparison output is inverted and supplied to the counter 43 during reverse.

On the other hand, the acceleration α output from the detection means 21 is supplied to the second window comparator 46 to obtain a fourth set value (corresponding to the first set value described above).
and its output is the up-down counter 4
The counter 47 is controlled according to the comparison output, and the output C obtained by the counter 47 is supplied to the arithmetic circuit 45. The arithmetic circuit 45 is further supplied with a value indicating the tape length r of the used tape obtained by the tape length detection means 48.

This arithmetic circuit 45 calculates the moments of inertia I _SR and I _TR of the supply side and take-up side reels from the above-mentioned data, but since the method of calculating them is the same as described above, the description thereof will be omitted. Then, the motor torques MT _S and MT _T are controlled so that the acceleration α becomes the fourth setting value and the tape tensions F _S and _FT become the fifth setting values, and the acceleration α and the tape tension F _S , F _T are respectively made to converge to the above-mentioned set values.

In this way, even with the structure simplified from the first embodiment, even if reels of different diameters are installed or the reel diameters differ between the supply side and the take-up side, the supply side and take-up side can be dynamically adjusted. The moment of inertia of the tape itself on the take-up side and the moment of inertia of the reel itself are detected, and the motor torque is controlled based on these detected data. Acceleration and tape tension can be controlled constant.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing an example of deceleration characteristics, and FIGS. 2 and 3 are system diagrams showing an example of the present invention. 1S and 1T are means for detecting tape winding diameters r _S and r _T ; 2
1 is means for detecting acceleration α; 23 and 25 are means for detecting tape tension; 20 is means for obtaining the moment of inertia of the reel; 22, 24, and 26 are comparison means;
41, 46 are window comparators, 10S,
10T is a motor torque calculation means.

Claims (1)

[Claims] 1. Means for detecting the rotational speed of the supply and take-up reels, means for detecting the tape speed, means for detecting the acceleration of the tape, means for detecting the tape tension in a portion near each of the above reels, and the above-mentioned a first comparing means for comparing the acceleration with a first set value; a second comparing means for comparing one of the tape tensions on the reel side with a second set value; means for controlling the first and second up-down counters with the comparison outputs of No. 2 and obtaining the moment of inertia of the reel itself from the outputs of the respective counters; It consists of means for obtaining the moment of inertia of the wound tape, and means for calculating the torque to be supplied to each reel from the respective moments of inertia of the reel and tape, and controlling the torque to each reel from the output of these calculations. . A tape running control device, wherein the tape acceleration and tape tension converge to first and second set values, respectively.