JP3126371B2 - Motor braking device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to motors, and more particularly, to motor braking.

[Related Art] In a hard disk drive device, an optical disk drive device, and the like, it is desired to rapidly accelerate and decelerate a disk. When decelerating the disk, it is desirable to brake the rotor of the motor coupled to the disk.

FIG. 5 shows a braking circuit of a DC brushless motor according to the prior art.

A controlled current is supplied from the motor drive IC 13 to the stator coil 11. A snubber circuit 14 for absorbing noise is connected to each of the stator coils 11. A rotor (not shown) arranged around the stator coil has a permanent magnet. The rotor driven by the stator coil 11 rotates to generate a vibrating magnetic field around the rotor. The Hall element 15 generates a Hall voltage by this magnetic field, and accumulates a voltage across the capacitor 16. This voltage is supplied to the motor drive IC 13 and forms a rotation monitor signal of the rotor. The current supplied to the stator coil 11 is controlled based on this monitor signal. A signal from at least one Hall element is supplied to an amplifier illustrated by an operational amplifier 17 in the figure, and forms an FG signal indicating the rotation speed of the rotor. The FG signal is supplied to the motor brake IC23 via capacitor C _7.

From the SPON terminal for instructing braking / driving (stop / rotation of the motor), a signal of 0 level during driving and 1 level during braking is supplied. This SPON signal is applied directly to the OR circuit 28 via the control circuit 29 and through the integration circuit 26. The output of the OR circuit 28 is supplied to the reverse torque generation instruction terminal 18 of the motor drive IC 13.

The function of the OR circuit 28 will be described with reference to FIG. The OR circuit 28 receives the signal Vi supplied from the control circuit 29 as described above.
Has an input directly received and an input received via the integration circuit 26.

As shown in the figure, it is assumed that the input signal Vi has a pulse-like waveform having a time length Tc, and the voltage Vh in the “1” state exceeds the input threshold Vth of the OR circuit 28. The integrating circuit 26 has a time constant R
Integrate the input voltage Vk with C. That is, the terminal voltage Vc of the capacitor C, as shown in the figure, gradually increases, exceeding the threshold value Vth at time t _1. In this state, both inputs of the OR circuit 28 are "1". Before long, the input signal Vi at time t ₂ is to be reduced to "0". At this time, the terminal voltage of the capacitor C starts discharging. For a while Vc is still the threshold Vt
Indicates a voltage higher than h. In this state, one input of the OR circuit 28 is “1”, and the output V ₀ maintains “1”. When the discharge of the capacitor C proceeds, eventually the terminal voltage becomes below the threshold Vth at time t _3. Because after this becomes both the OR circuit 28 is a two-input "0", the output V ₀ is also "0".

After the input signal Vi becomes “0”, the time length Td during which the output V _{0 of the} OR circuit keeps “1” depends on the time constant of the integrating circuit 26, the pulse length Tc of the input pulse, and the like.

Returning to FIG. 5, the motor brake IC23 has a crystal oscillator
An oscillation circuit 22 including 21 is connected, and this oscillation signal is frequency-divided by a frequency dividing circuit 24 to form a lower frequency reference signal. A reference signal, and the rotation represents FG signal supplied rotor via a capacitor C _7, are compared by comparator circuit 25, generating a braking control signal based on the difference. This braking control signal is supplied to the control terminal 19 of the motor drive IC 13 via the integration circuit 27, and performs the braking according to the rotation speed. The output terminal of the OR circuit 28 is connected to the output side of the comparator circuit 25 by the diode D _1.

With such a configuration, when the SPON signal becomes high level and braking is instructed, the terminal 18 of the motor drive IC 13
Is given a braking instruction. While the rotation of the rotor is high, the braking control signal is output from the comparison circuit 25 to the terminal 19 of the motor drive IC 13.
And a sufficient amount of braking is applied.

When the rotation of the rotor gradually decreases and reaches a predetermined value (for example, 1/8 of the constant rotation speed), the FG signal and the reference signal become equal, the output of the comparison circuit 25 changes, and the output of the control circuit 29 changes. Invert the signal to low level. When this low level is supplied to the terminal 18 of the motor drive IC 13, the braking operation stops. However, the OR circuit 28 has the integration circuit described above.
Since 26 is connected, after a certain delay time,
For the first time, the output change of the control circuit 29 is transmitted to the motor drive IC 13. During this time, the final braking is performed. That is, since it is difficult to monitor the low-speed rotation of the motor, the braking time is controlled by the delay time.

That is, when the rotor is braked and decelerated to reach a predetermined rotation speed, a signal for releasing the brake is generated from the motor brake IC 23, and the brake release signal is transmitted to the motor drive IC 13 after a lapse of a predetermined time. Within this predetermined time, the rotor is further braked, and becomes substantially at a rotational speed of zero. Incidentally, FG signal also supplies a signal to SPFG terminal through the transistor Tr _1.

By the way, there are two types of media, for example, glass and polycarbonate used for an optical disk device. Disk made these of a different material than the inertia also 100gcm ² ~2
Significantly different from 50gcm ²

[Problems to be Solved by the Invention] According to the conventional technique described above, the rotation of the rotor is monitored during braking, and the rotation of the rotor is, for example, 1/1 of the constant speed.
When the rotation speed decreases to a predetermined rotation speed such as 8, a braking release signal is generated, and braking is released after a predetermined delay time has elapsed. However, when the inertia of the rotor changes, such as when the medium of the disk changes, it is not easy to stop the rotation of the rotor accurately in a short time by such control.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor braking device capable of accurately stopping rotation of a rotor in a short time even when the medium changes.

Means for Solving the Problems A motor braking device according to the present invention includes a coil for generating a magnetic field for driving a rotor of a motor,
Means for generating a signal for commanding a stop, means for detecting the rotation of the rotor of the motor, means for generating a signal representing the rotation, and means for applying a reverse rotation torque to the rotor of the motor based on the rotor stop signal of the motor, A reference signal source for generating a reference signal of a predetermined frequency, and detecting the inertia of the motor rotor by detecting the length of time from when the rotor of the motor is started to when the rotor reaches a constant speed rotation, Means for selecting a delay time according to the value, means for comparing the reference signal and the signal representing the rotation, and means for generating a braking release signal when the rotation speed of the rotor decreases to a predetermined value; Means for stopping the generation of reverse torque when a time based on the selected delay time has elapsed after receiving the braking release signal.

[Operation] Since the delay time can be selected, the time from when the braking release signal is generated to when the braking is actually released can be selected.

By selecting the delay time according to the media,
It is possible to stop the rotor of the motor accurately and quickly.

Embodiment FIG. 1 schematically shows a braking device for a brushless DC motor according to an embodiment of the present invention.

The circuit according to this embodiment is the same as the circuit shown in FIG. 3, and the same reference numerals and symbols represent the same parts.

In this embodiment, a variable timer 1 is connected in place of the OR circuit 28 and the integrating circuit 26 connected to the input of the OR circuit 28 in the prior art shown in FIG. Variable timer 1 is
It is a variable timer that sets a different delay time depending on the difference in the media of the disk, and from when the braking signal is generated,
The braking signal is applied to the terminal 18 until the braking release signal is generated and a predetermined time based on the delay time elapses thereafter. The duration of braking after the generation of the braking release signal is determined by the type of the disk medium.

FIGS. 2A and 2B show two configuration examples of a variable timer circuit.

In the second diagram (A), to the two inputs of the OR circuit 28, the input signal Vi, a resistor R ₁ and the input signal capacitor
The value integrated by the integrating circuit including C ₁ and C ₂ is input. One of the capacitors C ₂ are the one input of the OR circuit 28 is connected via the transistor Tr ₂ and the ground.

The base electrode of the transistor Tr _2, if no current is fed, the transistor Tr ₂ is the capacitor C ₂ off does not function. Integrating circuit is composed of a running manner with the capacitor C ₁ and resistor R _1. The base electrode of the transistor Tr _2, when a drive current is supplied, the capacitor C ₂ in parallel with the capacitor C ₁
Is connected, the capacitance increases, and the time constant increases.

In FIG. 2 (B), the resistance R ₁ and the addition to the capacitor C _1, connected in parallel to the through transistor Tr ₃ to the resistor R ₁ a resistor R
₂ is included in the integration circuit. Transistor Tr ₂
To the base electrode, a drive current is supplied, the resistance R ₂ is the resistance
Is connected in parallel to R _1, the combined resistance is lowered. For this reason,
The time constant decreases.

Thus, according to the circuit of FIG. 2 (A), a variable timer circuit which selectively increases the time constant is obtained, and according to the circuit of FIG. 2 (B), the time constant is selectively reduced. Thus, a variable timer circuit is obtained. Note that such a variable timer circuit is not limited to the illustrated configuration.

The variable timer circuit as shown in FIG. 2 may provide the operator with a control signal according to the type of the medium, or may automatically detect the difference between the media.

FIG. 3 shows an embodiment in which the difference between the media is automatically detected and the delay time of the variable timer circuit is automatically set.

IC23a is the motor brake IC23 of the embodiment shown in FIG.
The terminal P11 has a rotation / braking signal which is high when the motor is stopped and low when the motor is rotating.
SPON is applied. The other terminal P12 generates a signal that goes high when the motor reaches the constant speed rotation. This signal becomes the base current of the transistor Tr _4, generates a SPLK signal at its collector terminal. That is, the signal SP
LK goes low when it reaches constant speed rotation, and goes high in other states. The signal SPON is applied to the terminal of the monomultivibrator 2, and when the signal SPON changes from a high state to a low state (when rotation is instructed), an output signal having a pulse length T is generated from the Q terminal. The output signal of the monomultivibrator is input to the data input terminal D of the flip-flop, and a signal indicating that the rotation has reached the constant speed (the output of the terminal P12 of the IC 23a) is applied to the clock terminal CK of the flip-flop. When the disk is formed of a light medium, the time required for the disk to reach a constant speed by a constant driving force is reduced. In this case, the output signal of the terminal P12 becomes high in a short time. If the disk is made of heavy media, the output signal at terminal P12 goes high for a longer time. The pulse length T of the output signal of the mono multivibrator 2 is set to a time intermediate between these two times.

That is, when the output signal of the terminal P12 becomes high after the pulse length T, the disk is formed with a heavy medium, and when the output signal becomes high before the pulse length T, the disk is formed with a light medium. You can see that it is done.

In this way, the flip-flop 3 detects the inertia of the disc, and supplies its output signal to the base electrode of the transistor Tr _2. Transistor Tr _2, depending on the inertia of the disk is on / off controlled, selectively connected in parallel to the capacitor C ₂ to the capacitor C _1.

Although the circuit for automatically detecting the inertia of the disk and selecting the delay time length that determines the braking time according to the inertia has been described, such a function can be achieved by other configurations.

FIG. 4 is a flowchart showing the control of the embodiment which achieves the same function by using a microprocessor. Note that the circuit shown in FIG. 2A is used as the variable timer circuit.

First, in step S1, the motor is stopped. In the next step S2, it is determined whether the rotation / braking signal SPON is at a low level. If it is at the low level, it means that the rotation of the motor has been instructed, and the process proceeds to the next step S3. If not, the motor remains stopped, and the process returns to step S2.

In step S3, the counter is counted up and the time after the rotation of the motor is measured. Next, in step S4, it is determined whether the constant speed rotation signal SPLK is at a high level. Here, it is assumed that the signal SPLK becomes a high level in the case of constant speed rotation. If the speed has not been reached, SPLK is not at the high level, and the process returns to step S3. In this way, the counter counts the time until SPLK goes high. When the motor reaches the constant speed rotation, step S4 becomes YES and the process proceeds to step S5. In step S5, the magnitude relationship between K indicating the activation time and T indicating the set value is compared. When the time K from when the motor is started to when the constant speed is reached is smaller than the set value T, it is determined that the inertia is small, and the process proceeds to step S6. In step S6, a low level output is supplied to the base of the transistor. That is, the transistor remains off. Therefore, the capacitance of the capacitor does not increase and the time constant keeps a low value.

In this way, a short delay time is selected for light inertia. In the next step S7, it is determined whether or not the motor has stopped. If the motor has not stopped, the process returns to step S6. When the motor stops, the process returns to step S1.

In step S5, when the time K from the start of the start to the constant speed rotation is greater than or equal to the set value T, it is determined that the inertia is large, and a high level is output to the base of the transistor (step S8). . That is, the transistor is turned on, connecting an additional capacitor in parallel with the capacitor, increasing the combined capacitance of the capacitor. In this way, the time constant increases.

A high time constant is selected for heavy inertia,
The braking is applied for a longer time. In step S9,
It is determined whether or not the motor has stopped. If the motor has not stopped, the process returns to step S8. When the motor has stopped, the process returns to step S1.

In this way, the software performs the same function as the circuit including the mono-multivibrator and the flip-flop shown in FIG.

Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[Effects of the Invention] As described above, according to the present invention, when braking the motor, the delay time is selected according to the inertia of the rotor, and the proper braking is performed, thereby quickly and accurately stopping the rotor. Can be done.

If the inertia measurement is automatically performed and the time constant is selected based on the result, the most suitable delay time is automatically selected and the motor is stopped.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a main part of a motor braking device according to an embodiment of the present invention. FIGS. 2A and 2B are circuit diagrams showing a configuration example of a variable timer circuit of FIG. FIG. 5 is a circuit diagram showing a main part of a motor braking device according to another embodiment of the present invention. FIG. 4 is a flowchart showing a control operation of the motor braking device according to another embodiment of the present invention. FIG. 6 is a circuit diagram showing a configuration of a motor braking device according to a conventional technique. FIG. 6 is a diagram for explaining an output of an OR circuit in the circuit of FIG. In the figure, 1... Variable timer 2... Mono-multivibrator 3... Flip-flop 13... Motor drive IC 23.

Claims (1)

(57) [Claims] 1. A coil for generating a magnetic field for driving a rotor of a motor, means for generating a signal for instructing rotation / stop of the rotor of the motor, and detecting a rotation of the rotor of the motor to generate a signal indicating the rotation. Means for applying a reverse rotation torque to the rotor of the motor based on a rotor stop signal of the motor; a reference signal source for generating a reference signal of a predetermined frequency; and A means for detecting the inertia of the rotor of the motor by detecting the length of time required to reach the constant speed rotation, selecting a delay time according to the value, and comparing the reference signal with the signal indicating the rotation. Means for generating a brake release signal when the rotational speed of the rotor has decreased to a predetermined value; and a time period based on the selected delay time after receiving the brake release signal. Means for stopping generation of reverse rotation torque when the time has passed.