JPH01318575A - Reverse torque brake circuit - Google Patents

Abstract

PURPOSE:To enable quick and reliable reverse torque brake operation by detecting the motor rotation in DC form then comparing the detected DC signal with a reference signal and detecting a stop frequency the comparison result thereafter releasing reverse torque brake operation. CONSTITUTION:When a motor is turned ON, an acceleration voltage composed only of a digital source voltage is applied from a servo IC11 onto a servo signal input port 3P. When the motor is turned OFF, the rotary direction input port 2P is brought to Rev while the servo signal input port 3P is brought to VBRK and the motor starts reverse torque operation. FG frequency decreases and the amplitude reduces as the motor decelerates, thus reducing the peakhold voltage V. When the peakhold voltage V drops below a reference voltage VS, output of a comparator 13 is brought to Low while the rotary direction input port 2P is brought to Fow, thus bringing the servo input port 3P to 0V and releasing the reverse torque brake mode. Thereafter, the disc rotates slightly in forward direction and stops.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reverse torque brake circuit for controlling the rotational speed of a spindle motor in, for example, an information recording/reproducing apparatus.

More specifically, the present invention relates to a reverse torque brake circuit that uses an external control signal to forcibly generate reverse torque to decelerate the vehicle.

[Prior Art] As is conventionally known, an information recording/reproducing apparatus is generally comprised of a spindle motor that rotates a disk-shaped medium at high speed, and a head unit that performs recording and reproduction. Nowadays, spindle motors are required to have large capacities, high transfer rates, and high speed access, so they are required to have high rotation accuracy, high speed rotation, and fast start-up and stop characteristics. To meet these demands, @-flow three-phase brushless motors are often used in spindle motors of information recording devices.

FIG. 4 shows a conventional spindle motor control circuit. Here, 1 is a motor driver IC, which has an FG amplifier 2 built therein. 3, 4.5 are drive coils for each phase (U, V, W). 6.7.8 is a Hall element that detects the rotational phase angle of each phase (U, V, W). The rotor is rotated by detecting the rotational phase angle of the rotor (not shown) by the Hall element 6.7.8 and bipolar driving any two of the drive coils. IP is an analog power supply line (VCC2). Vcc is a digital power supply. 2P is a human-powered boat in the rotation direction, and since the state in FIG. 4 is LOW, the rotor rotates in the normal direction. 3P is a servo control signal input terminal. The servo signal is fed back to the servo signal human-powered boat 3P as a signal obtained by frequency comparison or phase comparison of a reference signal (not shown) and the FG multiplied signal 6P, or as a signal obtained by mixing frequency comparison and phase comparison. FG double signal, FG coil 9, capacitors C2, C3, resistors R1, R2, R
3 and FG amplifier 2h) are made. 7P is the ground.

8P is a port to which a voltage-current conversion resistor R6 is connected, and determines the gain of the motor driver 1. R7,R
8, 119 and C7, C8, C9 are stabilizing resistors and capacitors, respectively. R4 and R5 are Hall elements 6
．． There are 7.8 bias voltage determining resistors, R4 is connected to the digital power supply Vcc, and R5 is connected to the ground. Capacitor [;4. C5 and C6 are high frequency noise removal filters.

Next, the operation of the motor drive circuit shown in FIG. 4 will be explained. When the motor is turned on (not shown), the servo signal 6P becomes old gh (phantom Vcc), and the motor accelerates. When the motor rotation speed approaches the target value, the servo is locked and the difference between the reference signal and the FG times signal is fed back to the servo signal input port 3P. Recording and reproducing are performed while the motor is in servo operation. When the motor is turned off,
The servo signal input boat 3P becomes Ov. At the same time, the switch IO is closed and the coils 3, 4.5 are short-circuited, thereby generating a back electromotive force and applying a brake to the rotation of the motor.

[Problems to be Solved by the Invention] However, the short brake as in the conventional example described above has the following drawbacks because the brake is applied by the back electromotive force generated from the rotation of the motor.

(1) The generated torque is small and it takes time to stop.

(2) At low speeds, the back electromotive force becomes very small and the brakes do not work.

Therefore, in view of the above-mentioned points, an object of the present invention is to provide a reverse torque brake circuit that enables quick and reliable braking.

[Means for Solving the Problems] The present invention provides a reverse torque brake circuit for controlling the rotation speed of a DC brushless motor, which includes a detection means for DC-detecting the rotation speed of the motor, an output signal of the detection means, and a reference signal. and a release means for detecting the stop frequency and releasing the reverse torque brake.

[Function] According to the present invention, when controlling the rotation speed of a DC brushless motor, the rotation speed of the motor is detected in a DC manner, and the detected DC signal is compared with a reference signal to detect a stop frequency. By releasing the reverse torque brake, quick and reliable reverse torque brake operation is possible despite the small number of parts.

[Example] Hereinafter, the present invention will be explained in detail based on Examples.

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and the explanation of parts that overlap with FIG. 4 will be omitted. Here, 11 is a servo IC, which uses a reference signal obtained by dividing the output of the crystal oscillator Xi, a low-pass filter composed of a resistor RIO and a capacitor CIO, and an inverter 1 with hysteresis.
5 and a capacitor C1l to compare the speed and phase of the FG multiplied signal manually, and the output is fed back to the service vehicle signal boat 3P via a diode 02. A peak hold circuit 12 converts the FG multiplied signal amplitude, which is the output of the FG amplifier 2, into a DC voltage.

The output V of the peak hold circuit 12 is compared with the reference voltage 5 by the comparator 13, and a stop frequency detection No. 18 (stop/rotation) is obtained. The stop frequency detection signal and the motor 0N10FF signal are integrated by an AND circuit 14, and are manually inputted to the rotating direction manual boat (FOW/Rev) 2P. Also, the output of the AND circuit 14 (V REV)
is divided by resistors R11 and RI2, and VBRK:
X VREV R11+R12 Brake voltage V BRK is applied to the servo signal human powered boat 3P.

Next, the operation of this embodiment will be explained using FIGS. 1, 2, and 3. Here, FIG. 2 is a timing chart from turning on the motor to stopping the motor, and FIG. 3 shows a flowchart at that time.

In FIG. 2, the motor is turned on at time t. The servo signal human powered boat 3P has a digital power supply voltage VCC.
, a high acceleration voltage is applied from the servo ICII. As shown in FIG. 3, the servo ICII starts servo operation at time t2 when the FG frequency ω approaches a point smaller than the target frequency ω0 by Δω0. Recording and reproduction of information becomes possible at this point. At this time, the comparator 1 node 13 output is ligh, but the motor is 0N10FF or Low.
(ON), the rotation direction of the human-powered boat 2P is Fow (L
ow), and the brake voltage VBRK is also Ov.

When the motor is turned off (high) at time jt3, the rotation direction large capo 1-2P becomes Rev (V, ), the servo signal human-powered boat 3P becomes Rev (V,), and the motor starts reverse torque operation. As the vehicle decelerates, the F6 frequency becomes lower, the amplitude becomes smaller, and the peak hold voltage ■ also becomes smaller (see Fig. 2).

When the peak hold voltage V becomes smaller than the reference voltage V5, the output of the comparator 13 becomes OW at time t4, and the rotational direction of the human-powered boat 2P becomes Fow (V row=
Ov), and the servo signal human powered boat 3P is also VllI
RK=OV, and the reverse torque brake mode is released.

After that, the disk rotates slightly in the forward rotation direction until time t
Stops at 5.

By changing the reference voltage ■3, the reverse torque brake can be released at an appropriate rotation speed. Also, resistors R11 and R12
By changing the partial pressure ratio, the strength of deceleration can be varied. Furthermore, by appropriately combining the reference voltage VS and the brake voltage VIIRK, it is possible to deal with discs of different inertia, and various reverse torque braking modes can be realized.

In the embodiment shown in FIG. 1, the peak hold circuit 12 is used to detect the FG multiplied signal amplitude and convert it to a DC voltage.
The FG frequency may be detected using a conversion circuit. This F
When a /V conversion circuit is used, it is also possible to detect the frequency of the 5-Hall element output.

In addition, the Hall element output is multiplied by the FG signal to the servo IC11.
It is also possible to perform servo control manually, and it is also possible to configure a motor rotation speed control circuit that does not use the CG coil 9. As a result, FG coil 9 and FG amplifier 2
By not using an amplifier circuit including an amplifier, costs can be reduced.

[Effects of the Invention] As explained above, in the present invention, during reverse torque braking of a DC brushless motor, the rotation speed of the motor is
By detecting the stop frequency detection signal (stop/rotation) by comparing the signal with the reference signal and releasing the reverse torque brake, the system is quick and inexpensive despite having a small number of parts. Smooth braking operation is possible. Furthermore, by appropriately changing the reference voltage and brake voltage, it is possible to accommodate disks with different inertia.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a motor rotation speed control circuit which is an embodiment of the present invention, Fig. 2 is a timing diagram showing the operation from turning on the motor to stopping the motor in Fig. 1, and Fig. 3 is a diagram showing the motor rotation speed control circuit in Fig. 1. Flowchart showing the control procedure from ON to stop. FIG. 4 is a diagram showing a conventional motor rotation speed control circuit. l...Motor driver IC1 2...FG amplifier, 9...FG coil, 11...Servo rc, 12...Peak hold circuit, 13...Comparator, 2P...Rotation direction signal input Boat, 3P... Servo signal human powered boat. tl t2 t3 t4
t5 (+ No. 10 + FG An 7° 2 Shock Force Figure 2

Claims (1)

[Claims] 1) In a reverse torque brake circuit that controls the rotational speed of a DC brushless motor, the circuit comprises: a detection means for detecting the rotational speed of the motor in a DC manner; and an output signal of the detection means is compared with a reference signal. 1. A reverse torque brake circuit comprising: a release means for detecting a stop frequency and releasing the reverse torque brake.