JPH02206388A - Spindle motor for disc drive - Google Patents

Abstract

PURPOSE:To reduce size, to save power and to suppress noise by providing a circuit for detecting the motor load and a switching power source for applying high voltage onto the motor when a heavy load is connected therewith. CONSTITUTION:A switching power source 2 is connected with a source terminal 1 and a load detecting circuit 3 is inserted into the power source. A motor circuit 4 is connected with the load detecting circuit 3. Output film the load detecting circuit 3 is connected with an oscillation circuit block 5 having output for controlling the transistor 21 in the switching power source 2. Since heavy load is applied onto the motor when it is started, for example, the load detecting circuit 3 functions to feed high voltage from the switching power source 2 to the motor. In other words, high voltage is applied onto the motor from the highly efficient switching power source 2 only when heavy load is applied onto the motor. By such arrangement, power is saved and noise is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to power saving of a motor for driving a recording medium of a disk drive device.

[Conventional technology] As shown in Fig. 7, the conventional technology uses a dedicated IC.
A method of driving a motor using a conventional method has been used in all disk drive devices.

FIG. 7 is a control circuit diagram of a conventional three-phase brushless motor.

Speed detector 101 and rotor position detector 102 a
, l O2b, 102c signals by dedicated ICI
input to O3, motor coils 104a, 104b, 1
04c to control the rotation of the motor.

Additionally, in some disk drive devices, as shown in FIG. 8, a method has been adopted in which the voltage applied to the motor circuit 106 is controlled by the switching power supply 105 based on the signal from the speed detection 5101, thereby increasing the efficiency of the motor. .

FIG. 8 is a motor control circuit diagram using a conventional switching power supply.

[The problem that the invention is trying to solve! ! ] However, in the conventional main shaft motor for a disk drive device, in the configuration shown in Figure 7, the internal transistor of the control IC is controlled in an analog manner, so the IC generates a lot of heat and the efficiency of the motor as a whole is low. Ta.

In addition, in the method of controlling the motor using a switching power supply as shown in Figure 8, although the efficiency of the motor is good,
This has had the problem of generating a large amount of noise due to switching and making the disk drive device prone to errors.

Therefore, in order to solve these problems, the present invention has been developed to provide a highly efficient disk drive device that generates less noise in response to the rapidly increasing demands for miniaturization and power saving of disk drive devices in recent years. The purpose is to provide main shaft motors.

[Means for Solving the Problems] In order to solve the above problems, the main shaft motor for a disk drive device of the present invention rotationally drives a disk-shaped recording medium,
A disk drive device that converts signals by a pickup is provided with a load detection circuit that detects the load on the motor for rotating the recording medium, and a switching f4R that applies a high voltage to the motor when the jt motor is heavy. Features.

[Function] When the motor load is normal, the main shaft motor for a disk drive device configured as described above is driven by the normal power supply voltage, and the switching power supply is not operating, so there is no noise generation, and the pickup There will be no negative impact on the.

However, when the load is heavy, for example when the motor is started, the load detection circuit is activated and a high voltage is supplied to the motor from the switching t4 source, causing a large current to flow through the motor, resulting in sufficient torque. can be obtained.

In this way, in the case of a normal motor load, a motor that does not generate noise and saves power can be obtained.

[Example] An embodiment of the present invention will be described below based on the drawings.

FIG. 1 is a motor control circuit diagram in the present invention,
FIG. 2 is a graph of the torque, rotation speed, and current of the motor according to the present invention.

In FIG. 1, a switching voltage R2 is connected to the power supply terminal 1.
is connected, and the load detection circuit 3 is inserted into the power supply. A motor circuit 4 is connected after the load detection circuit 3. Further, the output of the load detection circuit 3 is connected to an oscillation circuit block 5, and the output of the oscillation circuit block 5 controls a transistor 21 in the switching power supply 2.

In FIG. 2, the horizontal axis of the graph shows the motor load (torque), and the MI axis shows the motor rotation speed and motor current.

In such a configuration, the load detection circuit 3 detects the current flowing into the motor circuit 4, but the sea urchin graph in Figure 2 is a graph of current and load, and in a DC motor, the current increases according to the load. Therefore, by setting the detection current of the load detection circuit 3 to A, when the load exceeds TK, the load detection circuit 3 outputs a signal to the oscillation block 5, and the oscillation block 5 outputs a signal to the transistor of the switching power supply 2. 21 is driven and switched, and a high voltage vH is generated at the output terminal 22 of the switching power supply 2.

Note that the oscillation block 5 is just an oscillation circuit, and when there is no signal from the current detection circuit 3, the transistor 21 is turned off.
It is set to FF (detailed circuit configuration is omitted), and
The operation of the switching power supply 2 is also explained in detail in "Practical Electronic Circuit Handbook 3J" published by CQ Publishing Co., Ltd., page 276, etc., so the explanation will be omitted here.

Now, let us assume that the load applied to the motor is TM in Figure 2. In this case, since T<TK, the load detection circuit does not operate.Then, the voltage applied to the motor circuit 4 in Fig. 1 is the voltage applied to the power supply terminal 1 minus a small amount of loss. Added. The characteristic graph of the motor rotation speed and load at this time is vLT in FIG. This characteristic of vLT is the characteristic when no rotational speed control is applied to the motor.In reality, since control is applied at the rotational speed N, the rotational speed remains constant at N up to a certain negative ATL, and when the load exceeds This shows the characteristic graph of vLT.

Similarly, when a high voltage V is applied to the motor circuit 4, the characteristic graph of the motor rotation speed and jL street is vHT in FIG. In this case, even if the motor is increases to T, the motor rotation speed is maintained at N1.

Now, when starting the motor, it is necessary to drive the motor's own moment of inertia, and some recording media have a large inertia.

Some disk drive devices require a fast startup time, and the startup torque of the motor is required to be several times the torque (running torque) for rotating a normal recording medium.

However, once started, the running torque when converting signals by the pickup is light.

Therefore, when the motor starts, the load exceeds TK due to the moment of inertia, so the motor circuit 4 becomes ■. When the rotation speed becomes constant, the running torque of the recording medium becomes only, for example, T.
The load becomes M, and the motor circuit 4 operates with a voltage of VL.

Figures 3rlli and 4 are diagrams showing the above operations in terms of time.

FIG. 3 is a graph showing temporal changes in the voltage applied to the motor circuit of the present invention, and FIG. 4 is a graph showing temporal changes in the current flowing through the motor circuit of the present invention.

In FIG. 3, the horizontal axis represents time and the vertical axis represents the voltage applied to the motor circuit. In FIG. 4, the horizontal axis is the same time axis as in FIG. 3, and the vertical axis is the current flowing through the motor circuit.

Considering the case where the motor starts rotating from point A on the time axis, a large current flows through the motor circuit 4 as shown in FIG. 4 due to the movement of the recording medium and the inertia of the motor itself. Naturally, the set current I+c of the load detection circuit 3
Since a larger current flows, the switching power supply 2 shown in FIG. 1 is activated, and a high voltage <VH is applied to the motor circuit 4 as shown in FIG. 3.

With the passage of time, as shown in Figure 4, the motor times n4
The current flowing to
below one. Then, the load detection circuit 3 in FIG. 1 stops operating, and the voltage VL obtained by subtracting a slight loss from the voltage applied to the power supply terminal 1 is applied to the monitor circuit 4.

Of course, in this state, the switching power supply 2 is not operating, no noise is generated due to switching, and the signal conversion to the recording medium by the pickup starts from the 0 point on the time axis in Fig. 4. However, there is no risk of malfunction due to noise.In the disk drive device, the recording medium is started and the signal is converted by the pickup when the rotation speed becomes constant (after point C in Figure 4). Things are common.

If such voltage switching were not performed and the motor was operated using the conventional circuit shown in Figure 7, it would be necessary to always apply VH voltage to the motor circuit 4 to ensure the motor's characteristics. . In order to control the motor rotation speed to N1 in the state of running torque TM, the control IC 41 must consume a voltage corresponding to L2 in FIG. 2, and as in this embodiment, the voltage is set to vL. Control by events I
This is a large loss compared to the consumption L1 of C41, and it can be understood that the efficiency of the motor is poor.

Furthermore, compared to the conventional control circuit shown in Fig. 8, in the circuit shown in Fig. 8, the switching power supply does not operate even when the motor is in running torque and the pickup converts the signal. However, in this embodiment, the switching power supply is not operating in the state of running torque, so there is no possibility of malfunction due to noise.

FIGS. 5 and 6 show another embodiment of the present invention.

FIG. 5 is a graph showing temporal changes in the voltage applied to the motor circuit according to the present invention, and FIG. 6 is a graph showing temporal changes in the current flowing through the motor circuit according to the present invention.

In Figure 5, the horizontal axis represents the time axis, and the vertical axis represents the voltage applied to the motor circuit. In FIG. 6, the horizontal axis is the same time axis as in FIG. 5, and the vertical axis is the current flowing through the motor circuit. Note that the circuit configuration is the same as that in FIG. 1, so it is not particularly illustrated.

Considering the case where the motor starts rotating from point A on the time axis, a large current flows through the motor circuit 4 as shown in FIG. 6 due to the inertia of the recording medium and the motor itself. Naturally, since a current larger than the set current A of the load detection circuit 3 flows, the switching power supply 2 shown in FIG.
The parts where the high voltage H is applied are the same as in the previous embodiment. Next, as time passes, the motor current decreases as shown in FIG. It is set so that it changes according to the Therefore, the voltage applied to the motor circuit shown in FIG. 5 changes (decreases) until the current reaches point B on the time axis in FIG. The switching power supply 2 inside stops its operation, and a voltage vL obtained by subtracting a slight loss from the voltage applied to the power supply terminal 1 is applied to the motor circuit 4.

According to this embodiment, the voltage applied to the motor circuit is V
In addition to the two types of s and VL, the voltage between V and vL changes linearly according to the motor load, and because it is controlled by a high-efficiency switching power supply, the above-mentioned From the example, high motor efficiency can be obtained.

As explained above, the present invention is applicable to drive devices that use magnetic heads, optical pickups, etc. as pickups, and is applicable to flexible disk drive devices,
A wide range of applications are possible, such as hard disk drive devices and optical disk drive devices.

[Effects of the Invention] As explained above, the main shaft motor for a disk drive device of the present invention has a high voltage applied to the motor by a highly efficient switching power supply only when the load is heavy, and the switching power supply is not operated under normal loads. We can provide spindle motors for disk drive devices that are highly efficient, power-saving, and have low noise, and can be used to reduce the size, power consumption, and heat generation of disk drive devices, which have recently been in high demand due to the trend toward handheld and portable devices. This is a major contribution.

Furthermore, the output of the motor circuit is often bipolar driven, and when integrated into an IC, the operating voltage cannot be lowered very much, so an external drive transistor is required.According to the method of the present invention, Even when the motor circuit is integrated into an IC, the minimum operating voltage vL is guaranteed, so there is an advantage that the circuit can be integrated into an IC easily.

[Brief explanation of the drawing]

FIG. 1 is a motor control circuit diagram in the present invention. FIG. 2 is a graph of the torque, rotation speed, and current of the motor according to the present invention. 3 and 5 are graphs showing temporal changes in the voltage applied to the motor circuit in the present invention. FIGS. 4 and 6 are graphs showing temporal changes in the current flowing through the motor circuit in the present invention. FIG. 7 is a control circuit diagram of a conventional three-phase brushless motor. FIG. 8 is a motor control circuit diagram using a conventional switching power supply. 2... Switching power supply 3... Load detection circuit 4... Motor circuit 5... Oscillation block and above Applicant: Seven Iko Ebson Co., Ltd. Agent Patent attorney Yoshi Suzuki 3rd part 1 other person

Claims (1)

[Claims] A disk drive device that rotationally drives a disc-shaped recording medium and converts a signal using a pickup includes a load detection circuit that detects a load on a motor for rotationally driving the recording medium, and a high voltage applied to the motor when the load is heavy. A spindle motor for a disk drive device, characterized by being equipped with a switching power supply that adds