JPH01298982A - Reverse torque brake circuit - Google Patents

Abstract

PURPOSE:To always stably control by detecting a FG pulse interval and the rotating direction of a motor, and forcibly generating a reverse torque. CONSTITUTION:A reverse torque brake circuit generates a reverse torque by a servo IC 11, etc., and decelerates a motor. The IC 11 compares at speed and phase a FG signal input through a low pass filter formed of a resistor R10 and a capacitor C10, an inverter 15 with a hysteresis and a capacitor C11 with a reference signal of a crystal vibrator X1, and feeds it back to a servo signal input line 3P. A power ON reset signal is output by a resistor R12 and a capacitor C13. The output signals of Hall elements 6, 7 are input to a D latch circuit 18 through amplifiers 12, 13, etc., and the outputs of RS flip-flops 19-20, the output of the latch circuit and a signal of logic product 21 of a motor ON/OFF signal are input to a rotating direction input line 2P.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention is directed to a DC motor rotation speed control circuit included in a rotation speed control circuit of a DC motor, for example, a rotation speed control circuit of a spindle motor (DC brushless motor) in an information recording/reproducing device. This relates to the torque brake circuit.

[Prior Art] A conventionally known information recording/reproducing device has - in the shell,
It consists of a spindle motor that rotates a disk-shaped recording medium at high speed, and a head unit that performs recording and reproduction. Furthermore, as large capacity, high transfer rate, and high speed access are required, spindle motors require high rotational accuracy,
High rotation, fast start-up, and quick stopping are required.

In order to meet these demands, DC three-phase brushless motors are often used as spindle motors for information recording devices.

FIG. 12 shows a conventional spindle motor control circuit. Here, 1 is a motor driver (rc), and FG amplifier 2
Built-in. 3, 4, and 5 are drive coils for each phase (U, V, W). 6, 7.8 are Hall elements that detect the rotational phase angle of each phase (U, V, W). That is, the rotor is rotated by detecting the rotational phase angle of the rotor (not shown) by the Hall elements 6, 7.8 and bipolar driving any two of the drive coils.

IP is an analog power supply line (V CC2).

VCCI is a digital power supply. 2P is the rotation direction human power line (since it is Low in FIG. 12, it rotates in the normal direction). 3P is a servo signal input terminal. The servo signal is fed back to the servo signal input terminal 3P as a signal obtained by frequency comparison or phase comparison between a reference signal (not shown) and the FG signal 6P, or a signal obtained by mixing frequency comparison and phase comparison. The FG signal is composed of an FG coil 9, capacitors C2 and C3, resistors R1, R2, and R3, and an FG amplifier 2. 7P is the ground line.

8P is a line to which a voltage-current conversion resistor R6 is connected, and determines the gain of the motor driver 1. R7,R
8, R9 and C7, C8, C9 are a stabilizing resistor and a capacitor, respectively.

R4 and R5 are resistors for determining the bias voltage of the Hall elements 6 and 7.8, and R4 is a resistor for determining the bias voltage of the Hall elements 6 and 7.8.
5 is connected to ground.

C4, C5, and C6 are capacitors that act as filters for removing high frequency noise.

Next, the operation of the motor drive circuit will be explained using FIG. 12. When the motor rotation switch is turned on (- means low level), the servo signal human power line 6P becomes high level (#VCCI) (not shown) and the motor accelerates. When the motor rotation speed approaches the target value, the servo will be locked,
The difference between the reference signal and the FG signal is fed back to the servo signal human power line 3P. Then, recording and reproduction are performed while the motor is in servo operation. Further, when the motor switch is turned off, the servo signal human power line 3P becomes 0■. At the same time, the switch 10 closes and the coil 3.4.5 is short-circuited, so that a back electromotive force is generated and a brake is applied 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 braking is performed by a back electromotive force generated from motor rotation.

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

(2) When the rotation speed becomes low, the back electromotive force becomes very small.
Brakes don't work.

SUMMARY OF THE INVENTION Therefore, in view of the above-mentioned points, an object of the present invention is to provide a reverse torque brake system configured to always provide stable and sufficient braking ability.

[Means for Solving the Problems] In the present invention, a reverse torque brake circuit included in a rotation speed control circuit of a DC motor is provided with means for detecting the FG pulse interval and the rotation direction of the motor to release the reverse torque brake. do.

Further, the FG pulse interval detection circuit can include a monostable multivibrator, a rotor, and an RS flip-flop circuit.

Further, the circuit for detecting the rotational direction of the motor can include a two-output Hall element for detecting rotational phase and a D-type latch circuit. Alternatively, the circuit for detecting the rotational direction of the motor may include an FG signal generation circuit that generates two FG signals with different phases, and a D-type latch circuit.

In the monostable multivibrator circuit, the temperature dependence of the time constant can be set by adjusting the power supply voltage.

[Function] The reverse torque brake circuit according to the present invention forcibly generates reverse torque using an external control signal, thereby decelerating the motor.

[Embodiment] According to a preferred embodiment of the present invention, in the rotation speed control circuit of a DC brushless motor, the FG pulse interval is detected to form a stop frequency detection signal, and the two outputs of the Hall element for rotational phase detection are Alternatively, a rotational direction detection signal is formed from two FGs (#) with different phases, and the product of the two signals and the motor on/off signal (ONloFF) is calculated to enable quick and smooth braking operation. In other words, since there is a double brake release algorithm for the stop frequency detection signal and the rotation direction detection signal, even if a disc with a different inertia is mounted, or if the disc is rotated without a disc mounted, the brake can be released quickly without reverse rotation. allows for smooth stopping.

In addition, by adjusting the power supply voltage of the monostable multivibrator and adjusting the temperature dependence of the time constant τ5, stable reverse torque braking becomes possible over all environments.

FIG. 1 shows one embodiment of the invention. Here, explanations of elements that overlap with those in FIG. 12 will be omitted. Reference numeral 11 is a servo IC, which is manually operated via a reference No. 13 obtained by dividing the output of the crystal oscillator X1, a low-pass filter composed of a resistor RIG and a capacitor C1O, an inverter with hysteresis 16, and a capacitor C1l. Speed and phase comparisons are made with the FG signal, and the output is fed back to the servo signal input line 3P via the diode D2.

17 is a monostable multivibrator, FG
In response to the rising edge of the signal, only one pulse with a pulse width of a time constant determined by resistor R11 and CI2 is output. 1
9 and 20 are NAND gates and constitute an RS flip-flop. The circuit consisting of resistor R12 and capacitor C13 connected to the input terminal of NAND gate 20 prevents reverse torque braking even if the motor is turned off and then turned on when the power is turned off during motor startup or servo operation. Outputs a power-on reset signal for use.

The output signal of the Hall element 7 is sent to the clock input terminal (CK) of the D latch circuit 18, and the output signal of the Hall element 6 is sent to the data input terminal (D) of the D latch circuit 18.
．． 12 and inverter 15.14.

The AND signal of the output signal of the RS flip-flop, the output signal of the D latch circuit 18, and the motor 0N10FF signal is AN.
It is output from the D gate 21 and manually input to the rotation direction input line 2P. Furthermore, the output voltage V R of the AND gate 21
In the EV, a brake voltage v6□ divided by resistors R13 and R14 is inputted to the servo signal input line 3P.

Next, the operation of this embodiment will be explained using FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5. Here, FIGS. 2 and 5 are timing charts, and FIG. 3 is a flow chart.

When the motor is turned on at time t1 in FIG. 2, a digital signal voltage V
Accelerating voltage only for CCI is input. For servo ICII, the FG frequency ω is the target frequency ω. From Δω. When it approaches a small point, that is, ω0-ω(t2) = Δω
0, the servo operation is started (t2). Recording and reproduction of information becomes possible at this point. The motor is turned off at time t. Since the RS flip-flop output is high level and the D latch circuit output is also high level, the rotation direction human power line 2P is Rev (V REV = V CCI)
, the servo signal human power line 3P becomes as follows, and the reverse torque brake operation starts.

As the speed is decelerated, the FG pulse interval becomes longer. Time t
When the FG pulse interval becomes longer than C in the output pulse of the mono multivibrator 17 in 4, the RS flip-flop output becomes low level.

Since the level of the rotation direction human power line 2P is the logical product of the RS flip-flop output, the D latch output, and the motor level 10FF signal, it becomes FOIII (VFO, = Ov),
The servo signal human power line 3P also becomes VanK=Ov, and the reverse torque brake mode is released.

Thereafter, the disk 7 rotates slightly in the forward rotation direction and stops at time t5.

If you use a disc with light inertia without changing the partial pressure ratio for VBR, or if you brake the motor without using a disc, the deceleration will be too fast and the FG will be shorter than the pulse width τC of the mono-multivibrator 17. Reverse rotation may begin before the pulse width becomes longer. In this case, the output of the D latch circuit 18 releases the reverse torque brake.

This release operation will be explained using FIG. 4. The operation up to time t is the same as that shown in the third diagram.

If the deceleration is fast, reverse rotation starts before the FG pulse width becomes longer than the pulse width τC of the mono-multivibrator 17. When the reverse rotation starts, the phase difference between the output signals of the Hall elements 6 and 7 becomes opposite. Therefore, at time t4, the D latch output becomes low level, the rotation direction human power line 2P becomes the normal rotation level (Vrow=Ov), and the servo signal human power line 3P also becomes VBRK=OV. (Then, the reverse torque brake mode is released.The disc 7 then
It rotates slightly in reverse and stops at time t5.

Note that the output signal of the D latch circuit 18 is connected to the AND gate 21.
In a configuration where no input is made, the motor will run out of control.

A timing chart of this situation is shown in FIG.

with a time constant. For resistor R11 and capacitor C12
By changing the number of rotations, the reverse torque brake can be released at an appropriate rotation speed. with a time constant. By appropriately combining the brake voltage VBRK and the brake voltage VBRK, it is possible to handle discs with different inertias, and various reverse torque brake modes can be realized.

Next, a monostable multivibrator circuit will be explained.

FIG. 9 shows a detailed configuration of the monostable multivibrator 17 shown in the first figure. In Figure 9, C”MOS IC
TC4528 is used. The operating waveforms of this monostable multivibrator 17 are shown in FIG. 1O. 9th
When the rising clock on pin 4 shown in the figure is input manually, the resistance R
8 pulses are output from pin 6 with a time constant determined by 11, capacitor C12, and power supply voltage vcc. The threshold voltage (8) is determined by the power supply voltage VCCI.

It is known that the pulse width τ5 of the output pulse exhibits a large temperature dependence when the ambient temperature changes.

FIG. 11(A) shows the temperature dependence of S using the pulse width when the power supply voltage VCCI is 6.8V, and FIG. 11(B) shows the pulse width when the power supply voltage VCCL is 5.7V. As is clear from this figure, when the ambient temperature changes from 0° C. to 60° C., it changes by about 2.3 times at V ccl −5.7 V, and by about 1.7 times at V CC+−6.8 V. However, the power supply voltage VCC
It can be seen that as I is increased, its temperature dependence is also reduced. Here, in the fruitful isolated example of the invention shown in Figure 1,
Set the digital power supply voltage V CCI to 5. 6 from Ov. Ov
This reduces the temperature dependence of the time constant τ3 and enables stable reverse torque braking operation in all environments.

Next, other embodiments of the present invention are shown in FIGS. 6, 7, and 8.
This will be explained using figures.

Figure 6 shows two FG coils 9 and 22 with different phases, without using the Hall element output to detect the rotational direction of the motor.
is used. The signals output from the FG coils 9 and 22 pass through amplifiers 12 and 13 and inverters 14 and 15 with hysteresis, respectively, to the D-type latch data input terminal (
D) and the clock input terminal (CK). According to this embodiment, since the angular dispersion ability can be increased to about IO times that of a Hall element, it is possible to detect the direction of rotation more quickly.
The angle of reverse rotation when stopped can be further reduced.

FIG. 7 shows an example of a configuration in which a FG pattern is formed using sheet coils. Here, FG comb coils 23 and 24
are pasted together with their phases shifted.

FIG. 8 shows an example of the configuration when FG patterns 23 and 24 are formed on a PC board. That is, by generating the servo control FG signal from the outer FG pattern 23, more accurate rotation speed control becomes possible.

As mentioned above, during reverse torque braking of a DC brushless motor, a monostable multivibrator and an RS flip-flop circuit are used to detect the FG pulse interval and obtain a stop frequency detection signal (Revo/5to
p), the rotational direction detection signal (Fow
/Rev), and performs the logical product of the above two signals and the motor on/off signal (ONloFF) to release the reverse torque brake, thereby enabling quick and smooth braking operation. It is also possible to prevent runaway reverse rotation when the motor is suddenly decelerated.

Furthermore, set the digital power supply voltage to 5. By raising it to Ov or 66 or Ov, stable reverse torque braking operation becomes possible in all environments.

[Effects of the Invention] As described above, according to the present invention, since the configuration is such that reverse torque is forcibly generated by detecting the FG pulse interval and the rotational direction of the motor, stable and sufficient braking operation is always performed. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a motor rotation speed control drive circuit which is an embodiment of the present invention, FIG. 2 is a timing diagram of FIG. 1, FIG. 3 is a flowchart showing the operation of FIG. 1, and FIG. Another timing diagram in FIG. 1, FIG. 5 is a timing diagram showing reverse rotation that may occur when the D latch circuit shown in FIG. 1 is not provided, and FIG. 6 is a circuit diagram showing another embodiment of the present invention. , Fig. 7 shows an example of how to make an FG coil, Fig. 8 shows another example of how to make an FG coil, and Fig. 9 shows a monostable multivibrator circuit included in Fig. S1. Detailed diagram, Figure i10 is an explanatory diagram of the operation of the monostable multivibrator circuit, Figure 11 (A) is a diagram showing the temperature dependence of the time constant τS when the power supply voltage VCCI is 6.8V, Figure 11 (B) ) is a diagram showing the temperature dependence of the transition time constant τS when the power supply voltage VCCI is 5.7V, and FIG. 12 is a diagram showing a conventional motor rotation speed control circuit. l...Motor drive IC. 2...FG amplifier, 9...FG coil, 11...Servo IC,. 17... Monostable multivibrator, 18.
...D type latch circuit, 22...Second FG coil, 2P...Rotation direction human power line (FOW/REV), 3
P... Servo signal human power line. Fig. 3 Fig. 4 1 Forward rotation 1-G Kuwae Fig. 5 rFDkqtl@ (Fow/Rev) 1
2 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 (B)

Claims (1)

[Scope of Claims] 1) A reverse torque brake circuit included in a rotation speed control circuit of a DC motor is characterized by comprising means for detecting an FG pulse interval and a rotational direction of the motor to release the reverse torque brake. Reverse torque brake circuit. 2) The reverse torque brake circuit according to claim 1, wherein the FG pulse interval detection circuit comprises a monostable multivibrator and an RS flip-flop circuit. 3) The reverse torque brake circuit according to claim 1, wherein the circuit for detecting the rotational direction of the motor comprises a two-output Hall element for detecting rotational phase and a D-type latch circuit. 4) The circuit for detecting the rotational direction of the motor includes an FG signal generation circuit that generates two FG signals with different phases, and D
2. The reverse torque brake circuit according to claim 1, further comprising a type latch circuit. 5) The reverse torque brake circuit according to claim 2, wherein the monostable multivibrator circuit adjusts the temperature dependence of the time constant by adjusting the power supply voltage.