JPS59213051A - Reel driving control device - Google Patents

Abstract

PURPOSE:To always control tape feed operation to the prescribed operation without measuring a variation quantity against the variation of the constant of an object to be controlled such as the state of a tape quantity on a reel, the variation of a motor constant, the inequality of reel inertia, etc. CONSTITUTION:A transducer 6 receives a signal 7 detected by a tape tachometer 5 and generates a tape speed signal 8 and a tape displacing signal 9. A magnetic tape 1 is fed by driving a motor 11 which has direct-coupled a feed reel 2 by a motor shaft 10 and a motor 13 which is direct-coupled a winding reel 3 by a motor shaft 12. A motor control signal for controlling these motors 11, 13 is generated by controllers 14 and 15. Power amplifiers 16 and 17 are devices for excuting a power amplifying operation for driving the motors 11 and 13 by receiving said each motor control signal. Said controller 14 refers to the tape speed signal 8 detected by the tape tachometer 5 in order to feed the magnetic tape 1 by a prescribed tape length. A signal 18 based on a motor current is referred to for the purpose of stabilizing a reel driving control system. A control panel 15 also refers the tape speed signal 8 and to a signal 19 based on a motor current.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a tape transport device, particularly in a device that directly transports tape from reel to reel, for precisely and rapidly transporting a tape wound on a reel. The present invention relates to a reel drive control device suitable for.

[Background of the invention]

Generally, when a tape wound on a reel is transferred from one reel to the other, a magnetic head placed between both reels is used to record and reproduce signals on the tape. When performing reel drive control, first the amount of tape wound on the reel is counted. Subsequently, the counting results are used to derive the optimum electric current to be passed through the motor that drives the reel.

Problems with this control technology can be summarized into the following two points.

(Problem 1) The optimum current to be applied during Tanabata is closely related to the amount of tape wound on the reel, the inertial load of the reel itself, the inertia of the armature of the motor, and the constants of its components, such as the torque constant. There is a relationship between these constants, and in an actual device, the p value varies depending on manufacturing tolerances, operating temperature, etc. Such parameter variations of the components do not allow the motor current to be in an optimal state in the present control technique, and as a result, there is a drawback that the target specifications of the tape transfer call cannot be met.

(Problem 2) Related to Problem 1, when counting the amount of tape on a reel, in this case it may not be possible to directly count the necessary tape inertia, so in this control technology, the outermost radius of the reel is It is counted and substituted.

Therefore, if the material or thickness of the tape used changes, there is a drawback that accurate tape inertia cannot be derived.

[Purpose of the invention]

The object of the present invention is to use a magnetic head placed between both reels to always perform a predetermined operation even when the constant of the controlled object changes in a tape transport device necessary for recording and reproducing signals on the tape. The object of the present invention is to provide a reel drive control device that can perform the following functions.

[Summary of the invention]

In order to achieve the above object, technical issues regarding control are summarized. A technique for deriving the optimum motor current in order to transport the tape with a predetermined accuracy is required.

When deriving this motor current, we construct a control system that not only changes the amount of tape on the reel. If you include changes in the constants of the elements, the motor current will approach the optimum value. The present invention derives the optimum motor current based on this idea.

However, in actual cases, for example, due to manufacturing tolerance variations in motor constants, a dedicated device is often required for counting. On the other hand, the present invention does not derive the motor current by counting changes in the constants of individual components each time, but on the contrary, even if the constants of these individual components change, the tape feed υ The present invention provides a control device in which control performance such as accuracy is not affected.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 7. FIG. 1 is a diagram showing the overall configuration.

When the magnetic tape 1 passes the magnetic head 4 located between the supply reel 2 and the take-up reel 3,
Recording or reproducing signals on magnetic tape. Similar to the magnetic head 2, a chibuta tachometer 5 disposed between both reels detects the position of the tape when the magnetic tape 1 passes.

The configuration of the tape tachometer 5 includes an idler roller (not shown) that is rotatably installed and an encoder (not shown). A tacho generator may be used instead of the encoder. Transducer 6 receives signal 7 detected by tape tachometer 5 and generates tape speed signal 8 and tape displacement signal 9.

The magnetic tape 1 is fed by driving a motor 11 to which the supply reel 2 is directly connected through a motor shaft 10, and a motor 13 to which the take-up reel 3 is directly connected through a motor shaft 12. These motors 1
Motor control signals controlling 1 and 13 are generated by controllers 14 and 15.

The power amplifiers 16 and 17 are devices that perform a power amplification function to drive the motors 11 and 13 in response to the above-mentioned respective keyta control signals. Here, the controller 14 refers to the tape speed signal 8 detected by the tape tachometer 5 in order to feed the magnetic tape 1 by a predetermined tape length. A signal 18 based on the motor current is referenced for the purpose of stabilizing the reel drive control system. Controller 15 also references tape speed signal 8 and motor current based signal 19i for similar purposes. The method for detecting the amount of tape displacement is not a particular feature of the present invention, and any method may be used, but a method that can detect the tape speed at the same time is preferable.

Next, the configuration of a control device for transporting the magnetic tape 1 by a predetermined tape length will be explained. Here, the explanation will be given by taking the drive control system of the take-up reel 3 as an example, and the drive control system of the supply reel 2 is essentially the same as that on the take-up reel 3 side, so the explanation will be omitted. In Figure 1, the magnetic tape l
The tape feeding mechanism including the take-up reel 3 in a wound state, the tape tachometer 5, and the motor 13 that drives the take-up reel 3 will be collectively referred to as the controlled object 20.

If only the portion related to the take-up reel drive control system is extracted from FIG. 1 and displayed as a block diagram, it can be shown as shown in FIG. 2. The control amount 15 includes a target signal generator 21 that generates a displacement target signal as a pulse train, and a first generator that generates a digital value error signal by comparing the target signal with a tape displacement signal 9 that indicates the amount of actual tape displacement. An error detector 22 converts the error signal generated as a digital value into an analog signal 2.
It consists of a D/A converter 23 and a speed controller 25. This speed controller 25 includes a second error detector 26 and three amplifiers 27, 28, 2, as shown in FIG.
It consists of 9. Further, this speed controller 25 constitutes a speed closed loop control system 30 from the power amplifier 17 and the controlled object 20.

The three input signals of the precision controller 25 are the output signal 24 of the D/A converter 23 and the speed closed loop control system 30.
A signal 19 based on the motor current and a tape speed signal 8 for stabilizing the motor current. The amount of tape displacement is detected by a tape tachometer 5, and a tape speed signal 8 is detected by a converter 6.
and a tape displacement signal 9, and the tape displacement signal 9 is fed back to the first error detector 22.

Next, the operation for feeding the magnetic tape 1 by a predetermined tape length will be explained. First, problems that must be considered when controlling such a reel drive control system will be explained. As the magnetic tape 1 moves,
The amount of tape wound on the two reels varies. Changes in the tape on this reel have a great impact on controlling the data. For example, a change in the amount of tape on a reel changes the load on the motor, thereby affecting the acceleration at which the tape is started.

Next, a feature of the present invention in which the control performance is not easily affected by changes in the amount of tape wound on the reel will be explained. The controlled object 20 (
The frequency response characteristics of the tape feeding mechanism (including the take-up reel 3 with the magnetic tape 1 wound thereon, the tape tachometer 5, and the motor 13 that drives the take-up reel 3) are measured, and the gain characteristics are plotted in a Bode diagram. FIG. 4 is shown above.

Characteristic 31 indicates a state in which the amount of tape wound on the reel is large and the motor load is large, whereas characteristic 32 indicates a state in which the motor load is small. Next, in FIG. 5, characteristics 33 and 34 indicated by solid lines are frequency response characteristics measured in the same manner as in FIG. 4 for the speed closed loop control system 30 including the controlled object 20 and are shown on the Bode diagram. In Figure 5,
ω33 is the bandwidth of characteristic 33, and ω34 is the bandwidth of characteristic 44, and it can be seen that characteristic 34 with a small motor load has a wider bandwidth than characteristic 33. This bandwidth can be freely designed by adjusting the speed controller 25. This bandwidth generally indicates a frequency range in which a good response to an input signal can be achieved in a closed loop control system. Now, assuming that the characteristic 33 is the maximum motor load, and the characteristic 34'f is the minimum motor load, the bandwidth of this speed closed loop control system 30 changes from ω33 to ω34. , up to ω33, a good response to input signals can be expected. It can be seen that in the frequency range exceeding ω33, the response changes depending on the state of the motor load at that time. Due to this, the frequency vb where the influence of motor load does not appear
It is possible to distinguish between the frequency range and the frequency range in which it appears, with ω33 as the border.

In FIG. 5, a characteristic 35 indicated by a broken line indicates the target frequency response characteristic of the winding-loop motion control system.

(Open loop gain characteristics of control system).

The present invention is characterized in that the characteristic 35 is realized by applying an integrator that is originally included in the controlled object 20. To summarize the above, the take-up reel drive control system is a closed-loop displacement control system, and a closed-loop speed control system is further configured inside the take-up reel drive control system. Once the open loop gain characteristics of this control system are displayed on a Bode diagram, the solid line in FIG. ) as shown in Figure 6. What is clear from FIG. 6 is that in the frequency range up to frequency ω33, a response that is better than the design value is obtained. The influence of changes in the Tanabata load is limited to the frequency range of frequency 033 or higher. In FIG. 6, the responsiveness of the take-up reel drive control system can be determined by the intersection frequency ω0. Therefore, the frequency ω0 is crossed by the frequency ω33.
By designing it to be sufficiently high compared to , it is possible to realize a reel drive control system whose control performance is not affected by changes in motor load. So far, the explanation has been given using motor load changes as an example, but the explanation is not limited to motor loads, but applies to constant changes of all components that may affect response characteristics.

A speed controller 3g shown in FIG. 7 receives a tape speed signal 8 and a D/A converter 2 on the input side of the speed controller 25 shown in FIG.
an error detector 36 that compares the analog signal 24 from 3 with the analog signal 24 from
This has been improved by adding an integral amplifier 37 to eliminate the steady deviation of the tape speed signal.

According to the present invention, when starting or stopping the tape at a predetermined speed in order to record and reproduce signals on the tape, the condition of the amount of tape on the reel, variations in motor constants, and irregularities in reel inertia are detected. For constant changes in the controlled object, for example, a predetermined operation (
This is effective because the speed rise characteristic) can always be maintained.

Therefore, it is effective even for constant changes that cannot be corrected, and the adjustment work during assembly can be omitted, which is very effective during mass production.

〔Effect of the invention〕

As described above, according to the present invention, the tape feeding operation can always be controlled to a predetermined operation even when the constant of the controlled object changes.

[Brief explanation of the drawing]

1 is an overall configuration diagram illustrating an embodiment of the reel drive control device of the present invention, FIG. 2 is a block diagram showing an example of the take-up reel drive control system in FIG. 1, and FIG. 3 is a block diagram illustrating an example of the take-up reel drive control system in FIG. Block diagrams showing examples of speed controllers in FIGS. 4 and 5.
6 and 6 are Bode diagrams showing frequency response characteristics to explain the operation of the control system shown in FIG. 2, and FIG.
FIG. 3 is a block diagram showing another example of the speed controller in the figure. DESCRIPTION OF SYMBOLS 1... Magnetic tape, 2... Supply reel, 3... Take-up reel, 4... Magnetic head, 5... Tape tachometer, 6... Converter, 11.13... Motor , 14
．． 15... Controller, 20... Controlled object, 21...
Target signal generator, 22...first error detector, 23.
...D/A converter, 25.38...Speed controller, 26
...Second error detection 2'r, l 2Q device, 30...Closed loop control system, ←, W,? ? ... amplifier, 36 ... error detector, 37 ... integrating amplifier,
Agent Patent Attorney Akio Takahashi No. 1 Figure ¥J2 Figure 3 Figure fJ4 Figure B 1 ■ 5 Figure 8

Claims (1)

[Claims] The magnetic tape is transferred from the supply reel to the take-up reel through a read/write head provided between the reels by driving a supply reel and a take-up reel by separate motors, respectively, and this transfer allows magnetic tape to read and write information. In a tape device, a motor drive means for driving the motor according to a predetermined drive signal, a speed and displacement detection means for the magnetic tape, and an error detection means for detecting an error between a predetermined displacement target and the displacement of the magnetic tape. and speed control means for generating the drive signal so as to obtain a frequency section in which the response characteristics of the magnetic tape are not affected by constant changes of the components of the magnetic tape drive mechanism. Characteristic reel drive control device.