JPS63273269A - Controller - Google Patents

Abstract

PURPOSE:To surely apply control with simple constitution, by switching a control direction by a speed change detecting output in the turntable of a record player, etc. CONSTITUTION:A signal with a frequency proportional to the rotating speed of the turntable 1 is outputted from a head 2, and is converted to a voltage V at a frequency- voltage converter 3. The voltage V is compared with reference potential at a differential amplifier 4, and a driving motor 6 is servo-controlled via a power amplifier 5. When the table 1 is rotated reversely by a manual operation and rotating speed becomes less than reference rotating speed, the output of the amplifier 4 goes to a negative value, and the motor 6 is turned in a direction opposite to the same direction of manual turning, thereby, erroneous brake is applied. Then, the inversion of the output of the amplifier 4 to the negative value is detected by a comparator 9, and also, the output of an acceleration detector 7 goes to a positive value, and an FF11 is set via an AND circuit 10, then, the output of an amplifier 5 goes to 0 or the positive value, thereby, the erroneous acceleration of the motor 6 can be prevented from being generated. In such a way, it is possible to apply turning control surely with the simple constitution without necessitating the detection of a turning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in speed control devices such as turntables.

(Prior Art) The rotational speed of record player turntables and the like is controlled, but when the speed is changed and the rotational speed is controlled to stop, it is necessary to quickly shift to a predetermined speed. For example, in order to shift to a stop, an input that provides reverse rotation torque is applied to the motor, the brake is applied, and the control is terminated when a stop is detected.

(Problems to be Solved by the Invention) Due to the above-mentioned appearance and the fact that the reverse rotation torque is applied, if the stop control is activated while the turntable is being manually rotated in reverse, the absolute value speed control alone will result in high-speed reverse rotation. The direction of rotation of the turntable was detected.

This requires a frequency generator (FG) to obtain two-phase output, requires two detection heads, and has other limitations such as mechanical placement.

In view of these considerations, the present invention is designed to perform correct control using a single speed signal without requiring a special direction detector or the like.

(Means for Solving the Problems) The present invention determines and controls the direction by detecting whether a predetermined operation is being performed during control based on a speed change or a stop command, that is, by detecting an acceleration state.

(Example) FIG. 1 shows a block diagram of a turntable of the present invention and will be described. Constant 1 on the inner circle of the rim of turntable 1
Interval magnetic pulses are recorded and detected by the head 2 to detect pulses with a frequency proportional to the rotational speed of the turntable. This output is converted into a voltage output by a frequency converter (F-V converter) 3 and a voltage V proportional to the rotation speed is generated. As shown in FIG. 3, this is only a positive voltage regardless of the direction of rotation. Apply this voltage to the reference voltage S and set the rotation speed,
For example, Figure 3.3. According to the voltage, if the reference voltage is 45 rpm, this SI and the previous speed voltage V are applied to the differential amplifier 4.
The signal is amplified by the power amplifier 5, and the motor 6 is rotated to perform rotation servo. At this point, the voltage of Sb is O due to the stop.
When the rotation changes to vl or 331/3 and the rotation becomes 82, the output of the differential amplifier 4 becomes negative, and the motor 6 is given reverse rotation torque and quickly stops or shifts to 33 rotations. In case of a stop, a stop detector 8 is provided and its output O is used to cut off the control system. In this block diagram, the output from 0 onward is well known and will be omitted. Here, the stop detector is F-■ converter 3
This can be easily realized using a comparator since the output of the signal has reached the vicinity of Ov. As a result, the speed servo operates normally by simply converting the S voltage. However, here, for example, if the turntable is rotated in the reverse direction using manual -&E, and this reverse rotation speed is 33 rotations or more, and a rotation command of 33 rotations is given, the output of 3 will be because there is no direction detection. If you generate a voltage higher than the voltage of S2 corresponding to 33,
Therefore, the voltage to the motor is applied in the braking direction, and the motor is turned in the direction of accelerating the reverse rotation, causing the motor to rotate at high speed in the reverse direction. Here, in the present invention, an acceleration detector 7 is provided to prevent reverse rotation. The detector 7 can be realized with an RC integrator and a differential amplifier A as shown in FIG. That is, when the turntable accelerates, the direct voltage is always larger than the integral output, and when the turntable is decelerating, it becomes smaller. Therefore, during acceleration, a positive voltage is generated at the output of amplifier A.

A comparator 9 detects the case where the output of the speed comparator 4 becomes negative, and an AND circuit 10 extracts the AND result with the acceleration detector 7. This output indicates that when the rotation is fast and you try to apply the reverse brake, the original rotation is reversed and incorrect control is being performed.

Therefore, when this output occurs, the 7 lip-flop 11 is set, and this output applies a positive voltage to the power amplifier 5 so that the output of 5 becomes positive or 0 regardless of whether the output of 4 is negative, thereby increasing the reversal. Apply torque so that it rotates in the normal direction.

This causes the motor to stop and move in the forward rotation direction. During this time, the output of 4 approaches Ov and increases again. At this point, the previous stop detector releases the previous flip 70 knob and correctly enters the servo loose mode with only output 4. At this time, the output of 4 is normal and it operates correctly. Also, from 44 rpm to 331/
When changing to 3 or stopping, the brakes rotate in the opposite direction.
This occurs when the output of the acceleration detector 7 becomes negative, and it moves quickly, but the output of the acceleration detector 7 detects the deceleration state and the AND circuit 1
0 is not established and the brakes are applied correctly. This prevents only false reverse acceleration from being detected.

As described above, a device capable of preventing reverse rotational acceleration can be simplified in the same way as when a rotational direction detector is newly provided. As described above, it can be determined whether correct control is being performed by extracting the voltage applied by the servo system and the desired operation in the acceleration state.

In the example, prevention of high-speed reverse rotation was shown, but in addition, when controlling from forward rotation to stop, this block diagram is used when manual acceleration is performed to overcome the torque of the motor, which is not generally the case. In this case, it would be determined that the rotation is in the reverse direction, but a determination circuit may be added, and a circuit may be added to reset the flip-flop 11 if the output of the amplifier 5 accelerates regardless of whether it is positive.

By detecting the braking operation, that is, the acceleration state, in either direction, the correct operation can be determined depending on whether the acceleration is positive or negative, and if the brake operation is different, the polarity can be reversed. In this embodiment, a differential circuit is formed in the acceleration state detector using an integrating circuit and a comparator for detection, but it is of course possible to make a judgment by measuring changes in the interval of FG pulses using a digital counter. Moreover, it can be applied to a wide range of applications other than turntables.

(Effects of the Invention) According to the present invention, since the rotational speed of the motor is controlled by detecting acceleration, it is possible to provide a control device with a simple configuration and reliable operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a turntable according to the present invention, FIG. 2 is an example of an acceleration detector, and FIG. 3 is an explanatory diagram. ■... Turntable 2... Head 23... Frequency voltage converter 4... Differential amplifier 5... Power amplifier 6... Motor 7... Acceleration detector
8... Stop detector 9... Comparator 10
. . . AND circuit 11 . . . is a flip-flop. 15th! ! Item 3B

Claims (1)

[Claims] A speed control device using the same speed detection means irrespective of direction, which is provided with a speed change detection means and switches the control direction based on the output of the change detection means.