JPS61240869A - Motor decelerator - Google Patents

Abstract

PURPOSE:To always stably and smoothly decelerate and stop a motor by varying a brake current value in response to the period of an FG signal. CONSTITUTION:When a motor 15 is driven,the output of a frequency generator 14 is supplied through an amplifier 13, a rotating speed controller 12 and a switch 19 to a motor drive circuit 11. Whether the current of the motor 15 is driven by a rotation control loop or a brake current is flowed is switched by a switch 19 by a brake current switching circuit 20 at decelerating or stopping time. The periodic change of the FG signal is converted by an FG period detector 16, the output is input to a time constant circuit 17 to smooth the waveform, the output is input to a motor current limit setter 18 to convert it to a brake current, thereby supplying it through a switch 19 to the drive circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor deceleration device that decelerates and stops a motor smoothly and stably in as short a time as possible when the motor is being driven intermittently.

BACKGROUND OF THE INVENTION In recent years, magnetic recording and reproducing devices have become more and more multi-functional, and a wide variety of drive methods have been adopted for motors, including tape drive motors. Among these, a method for decelerating and stopping the motor in a short time and smoothly is required, and various methods are being used.

Hereinafter, a conventional motor speed reduction device will be described with reference to the drawings.

FIGS. 3 and 4 are a block diagram and a timing diagram of a conventional motor speed reduction device, respectively. 3 and 4, when the motor 16 rotates, the frequency generator 14 generates an FG signal 31, and this FG signal 31 is transmitted to the amplifier 1.
3, the waveform is shaped into a signal 32, and the rotational speed control circuit 12 applies speed control to the motor drive circuit 1.
1, the motor 15 is rotated at a constant speed. During deceleration, the FG cycle detection circuit 21 selects the point A from which deceleration starts.
A point B where the FG multiplied signal period has extended beyond a certain predetermined value is detected, and a high level signal waveform 61 is obtained from the point A to the point B. The brake current to the motor 16 is set to a sufficiently large constant brake current value by the brake current setting circuit 23, and the drive current to the motor drive circuit 11 is set by the switch 22 from the deceleration start point A to point B. It is opened and closed by the brake current setting circuit instead of the output of the control circuit 12, and during the high level period of the waveform 61, a sufficiently large constant brake current flows as the drive current to the motor 16, which is set by the brake current setting circuit 23. A motor current waveform 52 is obtained. Therefore, the motor 15 starts decelerating rapidly from point A and stops approximately at point B.

Problems to be Solved by the Invention However, in the above configuration, a constant brake current flows until the rotational speed of the motor decelerates to a certain speed. Therefore, due to changes in the motor load, etc., the motor may reverse slightly after it has stopped, making it difficult to decelerate and stop smoothly and stably.

In view of the above problems, the present invention provides a motor deceleration device that can smoothly decelerate and stop by changing the brake current in stages.

Means for Solving the Problems In order to solve the above problems, the motor speed reduction device of the present invention includes a motor rotation control loop consisting of a rotation speed detection means, a rotation speed control circuit, and a motor drive circuit. means for detecting the rotation period of the motor from the rotational speed detection means; means for changing the braking current of the motor in stages according to the output of the detection means; and means for changing the motor current based on the rotation control loop when the motor is stopped; The present invention is equipped with a means for switching the braking current in stages and steps.The present invention has the above-described configuration, so that even if the motor is decelerated in a short period of time, it is optimally adjusted according to the rotational speed of the motor from the start of deceleration to the stop. Since the brake can be applied using electric current, stable and smooth deceleration and stopping can always be achieved regardless of changes in motor load.

Embodiments Hereinafter, motor reduction gears according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram in one embodiment of the present invention,
FIG. 2 is a timing diagram. In FIG. 1, when driving a normal motor, first, a frequency generator 14 detects an FG signal 31 corresponding to the rotation speed of the motor 16, and after obtaining a waveform-shaped signal 32 through an amplifier 13, the rotation speed is controlled. A conventionally known rotation control loop is formed in which the voltage is applied to the circuit 12, the speed is controlled to a certain constant speed, and the motor 15 is driven by the motor drive circuit 11. During deceleration and stopping, the brake current switching circuit 20 switches the switch 19 to determine whether the motor current is driven by the rotation control loop or the brake current is applied.

The zero point in the timing diagram of FIG. 2 is the deceleration start point at which the brake current begins to flow. In addition, the FG period detection circuit 16
converts the periodic change of the FG signal 32 into a voltage and converts the FG signal 32 to voltage.
An output of a signal 33 corresponding to the period of the signal 32 is obtained.

Next, the waveform is blunted by the time constant circuit 17 and the signal 34 is
get the output of This output 34 is converted by a motor current limit setting circuit 18 into a brake current 35 at a level proportional to the output 34, and is supplied to the motor drive circuit 11 via a switch 19. Since the switch 19 is switched to the brake current side by the brake current switching circuit 20 from the deceleration starting point C, the motor current shown by the waveform 36 flows through the motor, and the motor decelerates stably and smoothly.

In addition, when converting the period change of the FG signal 32 into a voltage by the FG period detection circuit 16 to obtain the output of the signal 33 corresponding to the FG multiplied signal period, first, the FG multiplied signal period is set for a predetermined period or There is also a case where a sufficiently large brake current is applied continuously until the cycle reaches a certain constant period, and then the brake current is changed in accordance with the FG signal cycle as in the first embodiment, and the brake current waveform 38 is obtained. , the first
The same effects as in the embodiment can be obtained.

Effects of the Invention As described above, the present invention changes the brake current value in accordance with the FG multiplication signal cycle, so it is not affected by changes in motor load, etc., and always achieves stable and smooth deceleration and stop. I can do things.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a motor reduction device according to an embodiment of the present invention, Fig. 2 is a timing diagram of the same embodiment, Fig. 3 is a block diagram of a conventional motor reduction device, and Fig. 4 is a block diagram of the conventional motor reduction device. FIG. 11... Motor drive circuit, 12... Rotation speed control circuit, 16... FG period detection circuit,
17... Time constant circuit, 18... Current limit setting circuit, 20... Brake current switching circuit,
21...FG cycle detection circuit, 23...
Brake current setting circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure

Claims (2)

[Claims] (1) A motor, a frequency generator that generates an output signal with a frequency corresponding to the rotation speed of the motor, a speed control loop that controls the rotation speed of the motor to a predetermined constant speed, and the frequency generator detecting means for detecting the rotational speed of the motor based on the output signal of the detecting means; brake current generating means for generating a braking current for the motor that changes according to the output of the detecting means; A motor speed reduction device comprising: current switching means for applying the output of the brake current generating means to the motor instead of the current corresponding to the output. (2) A patent characterized in that the current switching means includes means for applying a predetermined constant brake current to the motor before stopping the motor, and then applying the output of the brake current generating means to the motor. A motor speed reduction device according to claim 1.