JPS633386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape reel drive device for a magnetic recording/reproducing device.

FIG. 1 is a control circuit diagram of a conventional tape reel drive device. In the figure, a tape reel 2 is directly connected to a motor 1. The load on this tape reel 2 changes depending on the amount of tape 3 wound thereon. Similarly, the radius of the tape reel 2 changes depending on the amount of tape 3 wound around it. In addition to the tape reel 2, a position detector 4 for digitally detecting the amount of rotational displacement is directly connected to the motor 1. The specification required of the tape reel 2 is to position a predetermined tape length within a predetermined time, and high precision and high speed are required at the same time. Also tape 3
Magnetic recording information is written on the tape 3, and writing and reading are performed on the tape 3 by an adjacent recording/reproducing mechanism (not shown), so the tape 3 has the necessary tape tension for constant recording and reproduction. has been added. Taking tape tension torque as an example, since the radius of the tape reel 2 changes depending on the amount of tape wound around it, the tape tension torque applied to the motor load also changes all the time. Even in this condition, the tape reel 2
requires a certain degree of positional accuracy. Regarding the rotational displacement of the motor 1 described above, the rotational direction and amount of rotational displacement of the motor 1 are detected by the rotational direction detector 5.
This information is fed back to the position detection counter 6 on the input side. The position detection counter 6 detects a positional deviation by comparing a motor control input inputted in advance to the motor rotational displacement amount information. This positional deviation is converted into an analog signal by the DA converter 7. One of the outputs of this DA converter 7 is sent to a phase compensation circuit 8, and the other is sent to an integrator 9.
is input. Phase compensation circuit 8 is operational amplifier 8
a, multiple resistors 8b, Zener diode 8
c, a capacitor 8d, and a switch 8e, which control dynamic characteristics of the tape reel drive device, such as overshoot. The integrator 9 also controls static characteristics of the device, such as steady-state deviation. The outputs of the phase compensation circuit 8 and the integrator 9 are added together by a summing amplifier 10 and then input to a power amplifier 11. A signal from a constant voltage source 12 is applied to the power amplifier 11. This signal is for causing the motor 1 to generate a compensation torque for compensating for the tape tension torque. These control signals are power-amplified by a power amplifier 11 to form a control system in which the motor 1 is driven.

There are major problems with the tape reel drive device described above. This is a change in the load on the tape reel 2. Even if you set the optimal gain for a given load, the load will change, so if the actual load is smaller than the given load, the control system will tend to overdamp and it will take a long time to reach the target stop position. It takes. In such a case, the specification of completing positioning within a predetermined time will no longer be met. On the other hand, if the actual load becomes larger than the predetermined load, the control system tends to underdamp and overshoot occurs, failing to satisfy the predetermined positioning accuracy. In addition, regarding reliability, it is necessary to take into account variations in manufacturing tolerances of the motor. In the current control method, it has been confirmed through experiments and simulations that increasing the loop gain of the control system reduces overshoot and improves positioning accuracy, but it takes longer to reach the specified tolerance. There is. On the other hand, increasing the speed will shorten the positioning time, but
Overshoot increases and positioning accuracy deteriorates. Furthermore, considering the causes of hunting and shaft resonance, there is an additional constraint that the loop gain of the control system cannot be selected very high. Currently, the current control method is approaching its limits in meeting the current specifications.

The present invention has been made based on the above-mentioned matters, and it is an object of the present invention to improve the performance and accuracy of the current tape reel drive device by several times.

The feature of the present invention is that, in the control system of the tape reel drive device, a
A means for improving the braking characteristics of the control system is provided, and this means weights the position error signal, improving the speed braking characteristics, shortening the positioning time, and realizing high speed.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of a control circuit for the tape reel drive device of the present invention, and in the figure, the same reference numerals as in FIG. 1 are the same parts. In this embodiment, a nonlinear amplifier circuit 13 is provided before the phase compensation circuit 8 to improve the braking characteristics of the control system.
Further, an inverting circuit 14 is provided before the integrator 9. Since the signal polarity of the DA converter 7 is inverted by the nonlinear amplifier circuit 13, the inverting circuit 14 inverts the polarity so that the polarity matches. The nonlinear amplifier circuit 13 is an amplifier 13
a, a resistor 13b, a capacitor 13c, and a diode 13d, and has nonlinear characteristics having two bending points as shown in FIG.

With this configuration, the DA converter 7
Since the position error signal from the motor 1 is weighted by the nonlinear amplifier circuit and added as a control signal to the motor 1, the braking characteristics of the control system are improved. That is, the position error signal is weighted by the nonlinear amplifier circuit and converted into a pseudo position error signal, which is then added as a control signal for the motor 1, so that the motor 1 operates based on this pseudo position error signal. As a result, the braking characteristics in the latter half of tape positioning are improved, and the positioning time can be shortened.

In the above embodiment, the nonlinear characteristics were realized by an analog circuit, but a memory storing the pattern of the nonlinear characteristics shown in FIG. 3 is provided between the position detection counter 6 and the DA converter 7. It may be provided and configured. Furthermore, the nonlinear characteristics shown in FIG. 3 can be stored as a functional expression, and this can be calculated and outputted by a microcomputer. Furthermore, the nonlinear characteristics shown in FIG. 3 can be replaced with a functional formula, and the system can be configured with a memory that stores the constants and variable values of this functional formula, and a dedicated hard circuit for performing functional calculations. Also, as shown in Figure 4
It is also possible to configure the DA converter 7 with nonlinear characteristics so that the nonlinear characteristics are obtained in the process of converting digital input to analog output.

As described in detail above, the present invention is configured to add weighting based on nonlinear characteristics to the position deviation signal sent to the motor that drives the tape reel, so that the braking characteristics, especially in the latter half of tape positioning, are improved. Positioning time can be shortened. As a result, it is possible to realize high-speed tape positioning. Further, according to the present invention,
Compared to conventional models, there is no need to increase the power, and the motor and power supply circuit can be used as is by simply modifying a portion of the control circuit.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a control circuit of a conventional tape reel drive device, FIG. 2 is a diagram showing an example of a control circuit of a tape reel drive device of the present invention, and FIG. 3 is a nonlinear amplifier used in the present invention. The characteristic diagram of the circuit, FIG. 4, is a diagram showing another example of the control circuit for the tape reel drive device of the present invention. 1... Motor, 2... Tape reel, 3... Tape, 4... Rotation detector, 6... Position detection counter, 7... DA converter, 8... Phase compensation circuit, 1
3...Nonlinear amplifier circuit.

Claims (1)

[Claims] 1. The rotational position of the tape reel connected to the motor is detected, this rotational position is fed back to the input side as a digital quantity, and the positional deviation between this rotational position quantity and the control input of the motor is calculated by DA. In a tape reel drive device in which the deviation control input is applied to the motor via a control system consisting of a converter, a phase compensation circuit, and a power amplifier, the output of the DA converter is input before the phase compensation circuit in the control system. A pseudo position error signal is inputted, and the pseudo position error signal increases in proportion to the increase in the position error signal, and the rate of increase decreases as the position error signal increases. A tape reel drive device characterized in that it is provided with means for outputting to a compensation circuit. 2. The tape reel drive device according to claim 1, wherein the means of the control system is a nonlinear amplifier. 3. The means of the control system includes:
2. The tape reel drive device according to claim 1, wherein the DA converter is a nonlinear DA converter.