JPH03250452A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To stop a DC motor for rotatively driving a magnetic disk in a short time by supporting a power source to a relay circuit for short-circuiting the DC motor via a resistor. CONSTITUTION:When the power source Vd is cut off to stop the DC motor 2, since a voltage corresponding to counter electromotive force of the motor 2 is impressed upon a power source line, a voltage obtained by dividing this voltage at a voltage dividing ratio corresponding to the resistor 10 and a resistance value of a driving coil 3m of a relay 3 is impressed upon the driving coil 3m. Consequently, the time required from cutoff of the power source up to turning-off of the relay 3 can be shortened, thus drastically reducing the time required for stopping the DC motor 2 after the power source is cut off.

Description

[Detailed Description of the Invention] [Industrial Application Fields] The present invention relates to a DC motor that rotationally drives a magnetic disk;
A relay circuit connected between the drive circuit supplies the back electromotive force generated in the DC motor when the power is cut off to a load circuit or a short circuit, thereby relating to a magnetic disk device.

[Prior Art] For example, in a magnetic disk device, in a DC motor used as a spindle motor to rotate a magnetic disk, a counter electromotive force generated is used to apply a current in the reverse direction to the DC motor when the power is cut off. This is called regenerative braking, in which the DC motor is suddenly braked.

FIG. 7 shows an example of a drive circuit for a DC motor.

The motor disturbance integrated circuit 1 rotates a three-phase DC motor 2, and receives drive signals SA and SB.

SC is the connection end PA of the field winding of the DC motor 2, P
B, added to PC.

Further, the connecting end PA of the DC motor 2 is connected to one common terminal 3ac of the two contact circuits 3a and 3b of the relay 3, and the connecting end PB is connected to the other common terminal 3bc of the relay 3. The connection end PC is connected to normally closed contacts 3ab and 3bb of the relay 3.

Further, the normally open contacts 3aa and 3ba of the relay 3 are open, and the power supply Vd from the power supply line is applied to the drive coil 3I11.

In the above configuration, before the power is turned on, the power supply Vd is not applied to the drive coil 3m of the relay 3, so the relay 3 is in an OFF operation, thereby causing the contact circuit 3a
, 3b are switched to the normally open contacts 3ab and 3bb, and as a result, the connection ends PC of the DC motor 2 are connected to the connection ends PA and PB, respectively.

In this state, when the power is turned on, the power supply Vd is applied to the drive coil 3.
m, the relay 3 is turned on, and the contact circuits 3a and 3b are normally closed contacts 3aa and 3ba.
side, so that the connection end P of the DC motor 2
A, PB, and PC each have an integrated circuit for motor oscillation]
The drive signals SA, SB, and SC are ready to be applied.

As a result, when the motor drive integrated circuit 1 outputs the drive signals SA, SB, and SC at appropriate timings to rotationally drive the DC motor 2, the drive signals SA, SB
, SC are the connection ends PA and PB of the DC motor 2, respectively.
.

The voltage is applied to PC, thereby driving the DC motor 2 to rotate.

From that state, in order to stop the DC motor 2, the power supply Vd
When the power supply Vd is cut off, the power supply Vd is no longer applied to the drive coil 3m, so the relay 3 is turned off, and as a result, the contact circuits 3a and 3b are switched to the normally open contacts 3ab and 3bb, and as a result, the DC motor 2 The connection end PC is
They are connected to connection ends PA and PB, respectively.

Thereby, the back electromotive force generated from the DC motor 2 is applied to the field winding of the DC motor 2 itself.

In this case, the polarity of the back electromotive force is determined by the drive signals SA, SB, and S.
Since the polarity is opposite to that of C, the DC motor 2 is braked and stopped.

In this way, when the power is cut off, the back electromotive force of the DC motor 2 is regenerated to the DC motor 2, thereby rapidly braking the DC motor 2.

[Problems to be Solved by the Invention] However, such conventional devices have the following disadvantages.

That is, in general, for example, as shown in FIG. 8, in the motor drive integrated circuit 1, the power transistor TRI constituting the final stage of the output circuit that outputs the drive signal SA;
A protective diode D1 is connected to TR2. ．． D2 are connected in parallel, and when the power is cut off, the current IG caused by the back electromotive force generated from the DC motor 2 flows through this diode D.
1 to the power supply line.

As a result, as shown in FIGS. 9(a) and 9(b), when the power is cut off at time ta, a voltage Vm corresponding to the back electromotive force of the DC motor 2 is applied to the drive coil 3m of the relay 3.

This voltage Vm decreases as the rotational speed of the DC motor 2 decreases, and at time tb when its magnitude becomes smaller than the threshold voltage Vt for turning on the relay 3, the relay 3 turns off.

In this way, the relay 3 maintains its ON operation from the time ta when the power is cut off until the time tb when the time TA has elapsed, causing the inconvenience that it takes time for the motor 2 to stop.

The present invention has been made to solve the above-mentioned disadvantages of conventional devices, and an object of the present invention is to provide a magnetic disk device that can stop a DC motor in a short time.

[Means for Solving the Problems] According to the present invention, power is supplied to a relay circuit for short-terminating a DC motor via a resistor, a diode, or a Zener diode.

[Accordingly, the active coil of the relay circuit has a voltage corresponding to the back electromotive force of the DC motor divided according to the voltage division ratio between the resistor and the cantering coil, or a voltage corresponding to the back electromotive force. A voltage that is the forward voltage of the diode lower than the voltage applied, or a voltage that is the Zener voltage of the Zener diode lower than the voltage corresponding to the back electromotive force is applied.
The relay circuit turns off in a very short time, and the DC motor can be stopped in a short time.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a DC motor drive circuit according to an embodiment of the present invention. In addition, in this figure, the same parts as in FIG. 5 are given the same reference numerals.

In the figure, a power supply Vd from a power supply line is applied to a drive coil 3m of a relay 3 via a resistor 10.

Therefore, the voltage Vk applied to the drive coil 3a is
It is a value obtained by dividing the voltage of the power supply line by a ratio corresponding to the resistance values of the resistor 10 and the drive coil 3a.

In the above configuration, before the power is turned on, the power supply Vd is not applied to the drive coil 3m of the relay 3, so the relay 3 is in an OFF operation, thereby causing the contact circuit 3a
, 3b are switched to the normally open contacts 3ab and 3bb, and as a result, the connection ends PC of the DC motor 2 are connected to the connection ends PA and PB, respectively.

When the power is turned on in this state, as shown in Fig. 2, a voltage obtained by dividing the voltage of the power supply Vd by the voltage division ratio of the resistor 10 and the drive coil 3m is applied to the drive coil 3m, and the relay 3 is turned on. operates, thereby contact circuits 3a, 3b
are switched to the normally closed contacts 3aa and 3ba, and as a result, the drive signals SA and SB of the motor drive integrated circuit 1 are applied to the connection ends PA, PB, and PC of the DC motor 2, respectively.

SC is ready to be applied.

As a result, when the motor drive integrated circuit 1 outputs the drive signals SA, SB, and SC at appropriate timings to rotationally drive the DC motor 2, the drive signals SA, SB
, SC are the connection ends PA and PB of the DC motor 2, respectively.
.

The voltage is applied to PC, thereby driving the DC motor 2 to rotate.

From that state, in order to stop the DC motor 2, the power supply Vd
When the voltage V+ is cut off, a voltage Vm corresponding to the back electromotive force of the DC motor 2 is applied to the power supply line.
The voltage Vk obtained by dividing n by a voltage division ratio corresponding to the resistance values of the resistor 10 and the drive coil 3m is the voltage Vk that is applied to the active coil 3 of the relay 3.
applied to m.

This voltage Vk decreases as the rotational speed of the DC motor 2 decreases and the voltage Vm decreases, and at time tc when its magnitude becomes smaller than the threshold voltage Vt for ON operation of the relay 3, the relay 3 is turned on. Works off.

In this way, the relay 3 is turned off at time tc when time TB has elapsed from time ta when the power was cut off.

Here, since a voltage of a value obtained by dividing the voltage of the back electromotive force is applied to the drive coil 3m of the relay 3, the time TB is
This is shorter than the time TA required for the conventional device to turn off the relay 3 after the power is cut off.

In this way, in this embodiment, the time required for the relay 3 to turn on after the power is cut off can be shortened, thereby significantly reducing the time required for the DC motor 2 to stop after the power is cut off. can do.

FIG. 3 shows a DC motor drive circuit according to another embodiment of the invention. In addition, in this figure, the same parts as in FIG. 1 are given the same reference numerals.

In the figure, a diode 11 is connected in the forward direction between the drive coil 3m of the relay 3 and the power supply line.

With the above configuration, as shown in FIG. 4, when the power is turned on, the diode 1
A voltage Vn with a value obtained by subtracting the forward voltage drop of 1 is applied to the drive coil 3m of the relay 3, thereby turning on the relay 3, and in the same manner as in the above embodiment, the motor drive integrated circuit Drive signals SA, S output from 1
B and SC are connection ends PA of the DC motor 2, respectively.
In addition to PB and PC, a DC motor 2 is rotationally driven.

When the power is cut off from this state, the voltage Vn, which is the voltage Vm corresponding to the back electromotive force of the motor 2 minus the forward voltage drop of the diode 11, is applied to the drive coil 3m of the relay 3.
The voltage Vn decreases as the voltage Vm decreases, similar to the embodiment described above.

Then, at time td when the magnitude of the voltage Vn becomes smaller than the threshold voltage Vt for turning on the relay 3, the relay 3 turns off.

In this way, relay 1 and relay 3 are operated at the time ta when the power is cut off.
It turns off at time td when time TC has elapsed since then.

Here, in this embodiment, a voltage equal to the voltage of the power supply line minus the forward voltage drop of the diode 11 is applied to the drive coil 3m of the relay 3, which is different from the embodiment shown in FIG. On the contrary, the difference between the voltage applied to the drive coil 3m and the voltage of the power supply line does not change.

That is, in the embodiment shown in FIG. 1, the voltage Vk applied to the drive coil 3m after the power is cut off changes so as to have a constant voltage division ratio with the voltage Vm corresponding to the back electromotive force of the DC motor 2. In the embodiment shown in FIG. 3, the voltage Vn applied to the drive coil 3m after the power is cut off changes so as to have a constant difference from the voltage Vm.

For this reason, the time TB required from shutting off the power until the relay 3 turns off in the embodiment of FIG. 3 is longer than the time TB required from shutting off the power to turning off the relay 3 in the embodiment of FIG. TC is shorter.

According to experiments conducted by the present inventors, in the conventional device, the time TA required from the power cutoff to the relay 3 turning off was 3.3 (seconds), whereas the resistance value of the resistor 10 When set to 100 (ohm), the time TB is 0°75 (
(seconds), and the time TC was 0.64 (seconds).

FIG. 5 shows a DC motor drive circuit according to yet another embodiment of the present invention. In addition, in this figure, the same parts as in FIG. 1 are given the same reference numerals.

In the figure, a Zener diode 12 is connected in the opposite direction between the drive coil 3m of the relay 3 and the power supply line.

With the above configuration, as shown in FIG. 6, when the power is turned on, a voltage Vz equal to the value obtained by subtracting the Zener voltage of the Zener diode 12 from the voltage Vd of the power line is applied to the drive coil 3m of the relay 3. As a result, the relay 3 is turned on, and the drive signals SA, S output from the motor drive integrated circuit 1 are activated in the same way as in the above-described embodiment.
B and SC are the connection ends PA and PB of the DC motor 2, respectively.
In addition to the PC, the DC motor 2 is rotationally driven.

When the power is cut off from this state, a voltage equal to the voltage Vm corresponding to the back electromotive force of the motor 2 minus the Zener voltage of the Zener diode 12 is applied to the drive coil 3m of the relay 3.
, and its voltage decreases as voltage Vm decreases, similar to the embodiment described above.

Then, at time te when the magnitude of the voltage becomes smaller than the threshold voltage Vt for ON operation of the relay 3, the relay 3
works off.

In this way, the relay 3 turns off at time te, which is a time TD that has elapsed from time ta when the power was cut off.

Here, for example, the voltage Vd of the power supply line is set to 12 (V).
The rated voltage of the relay 3 is 9 (V), the Zener voltage of the Zener diode 12 is 2.9 (V), and the voltage Vm of the back electromotive force of the motor 2 is 3.7 (V). In addition, in this case, the threshold voltage V at which the relay 3 turns off is
Since t is 10% of the rated voltage, it becomes 0.9 (V).

Under these conditions, when the power is turned on, the drive coil 3 of relay 3
Since a voltage of 9.1 (=12-2.9) (V) is applied to m, the relay 3 is turned on and power is appropriately supplied to the motor 2.

Immediately after the power is cut off, a voltage of 0.8 (=3.7-2.9) (V) is applied to the drive coil 3m of the relay 3. Immediately after the power is cut off, the voltage applied to the coil 3m is lower than the threshold voltage Vt of the relay 3, so the relay 3 is immediately turned off, and the power supply to the motor 2 is cut off after the operation delay time has elapsed. Been,
Motor 2 stops.

According to experiments conducted by the present inventors, the time TD from the time ta when the power was cut off until the motor 2 stopped was measured under the above-mentioned conditions, and the value was 0.1 seconds. In this way, in this embodiment, the motor 2 can be turned off in a very short time after the power is cut off.

In this manner, in each of the embodiments described above, the time required from the time the power is cut off until the relay 3 is turned off can be significantly shortened.

By the way, in the above embodiment, either a resistor or a diode is connected in series between the drive coil of the relay and the power supply line, but these elements can also be connected in series.

Note that in the above description, detailed descriptions of parts not directly related to the present invention are omitted.

[Effects of the Invention] As explained above, according to the present invention, power is supplied to a relay circuit for shorting a DC motor through a resistor, a diode, or a reversely connected Zener diode. The drive coil is supplied with a voltage obtained by dividing the voltage corresponding to the back electromotive force of the DC motor according to the voltage division ratio between the resistor and the drive coil, or a voltage corresponding to the back electromotive force divided by the forward voltage of the diode. Since the reduced voltage or the voltage corresponding to the back electromotive force is applied, which reduces the Zener voltage of the Zener diode, the relay circuit turns off in a very short time, and as a result, the DC motor can be turned off in a short time. Obtain the effect of being able to stop.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a DC motor drive circuit according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram for explaining the operation of the device shown in FIG. 1, and FIG. 3 is a block diagram showing a DC motor drive circuit according to an embodiment of the present invention. A block diagram showing the DC motor active circuit according to the embodiment, FIG. 4 is an operation waveform diagram for explaining the operation of the device in FIG. 3, and FIG.
FIG. 6 is a block diagram showing a DC motor recording circuit according to still another embodiment of the present invention, FIG. 6 is an operation waveform diagram for explaining the operation of the device shown in FIG. 5, and FIG. 7 is a DC motor drive circuit. 8 is a circuit diagram showing an example of the configuration of the output final stage of a motor-related integrated circuit, and FIG. 9 is an operation waveform diagram for explaining the operation of the device shown in FIG. 8. . 10...Resistor, 11...Diode, 12...
zener diode.

Claims (3)

[Claims] (1) A relay circuit connected between the DC motor that rotationally drives the magnetic disk and its drive circuit supplies the back electromotive force generated in the DC motor when the power is cut off to the load circuit or short circuit to drive the magnetic disk drive. A magnetic disk device characterized in that power is supplied to the relay circuit through a resistor. (2) A relay circuit connected between the DC motor that rotationally drives the magnetic disk and its drive circuit supplies the back electromotive force generated in the DC motor when the power is cut off to the load circuit or short circuit to drive the magnetic disk drive. A magnetic disk drive characterized in that power is supplied to the relay circuit through a forward-connected diode. (3) A relay circuit connected between the DC motor that rotates the magnetic disk and its drive circuit supplies the back electromotive force generated in the DC motor when the power is cut off to the load circuit or short circuit to drive the magnetic disk drive. A magnetic disk drive characterized in that power is supplied to the relay circuit through a Zener diode connected in the opposite direction.