KR100480189B1 - Brushless motor controller and disk device using the same - Google Patents

Abstract

A brushless motor control device includes: a brushless motor including a rotor magnet and a stator coil; Rotor position detecting means for detecting a plurality of magnetic pole positions of said rotor magnet; Vibration detection means for detecting unnecessary vibration of the brushless motor when the brushless motor is rotating; Lead angle setting means for setting the size of the lead angle such that the first output of the vibration detecting means does not exceed a predetermined allowable value; According to the second output of the lead angle setting means, driving to the stator coil to provide a lead angle to the third output of the rotor position detecting means to provide the brushless motor with an always optimal lead angle corresponding to the required number of revolutions And lead angle correction means for generating an electric current timing of electric current.

Description

Brushless motor controller and disk device using the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor control device and a disk device using the same, and more particularly, to a brushless motor control device for changing a characteristic of a motor by setting a lead angle, and a disk device using the same. will be.

Conventionally, a plurality of types of information discs having different recording formats are handled by one type of disc device which records information thereon and reproduces information therefrom. For example, in the case of optical discs, disc devices which deal with discs such as DVD-ROM discs, DVD-RAM discs, CD-ROM discs and the like have been put to practical use.

Often, this type of disk device is designed to provide all the functions necessary for recording and reproducing various kinds of disks to respective components, such as heads, disk motors, signal processing LSIs, and the like. Therefore, the conditions set for one type of disc can disturb the conditions of another type of disc, which hinders the performance improvement.

For example, when designing a disk motor, the characteristics of the motor are often determined by the rotational conditions of the disk that is rotated at the highest speed among all kinds of disks used in the disk motor. In this case, to reduce the counter electromotive force of the motor, for example, to reduce the number of linkage magnetic fluxes between the rotor magnet and the stator coil, for example, the number of turns of the coil This reduces the torque generated per unit current (torque constant). As a result, for example, inconvenience occurs in that the generated torque of the motor is reduced, and the time required for changing the rotational speed of the motor to the target rotational speed is increased.

For example, in the case of disc devices dealing with discs such as DVD-ROM discs, DVD-RAM discs and CD-ROM discs, spindle motors are used to write information to and reproduce information from the DVD-RAM discs. Required rotation speed is up to about 3250 rpm. In order to increase the seek operation speed for the purpose of performing ZCLV (Zoned Constant linear velocity) control, high torque is required at speeds in the range of 1350 to 3250 rpm (comparatively low speed). In order to record information on or reproduce information from CD-ROM discs, high-speed playback is urgently needed. There is often a need to play information on CD-ROMs at speeds of 40 times or more. To realize this, a maximum rotational speed of about 9000 rpm is required. Since such high speed rotation is necessary only for reproduction, it is not necessary to change the rotation speed during the search operation, for example, thanks to the circuit of the jitter free configuration. Therefore, very high torque is not necessary for the search operation.

As described above, when the motor coil is designed to provide high rotational speed and low torque to realize the high playback speed required for CD-ROM discs and DVD-ROM discs, a high speed search for DVD-RAM discs. The high torque required for operation is not obtained. In contrast, when the motor coil is designed with more turns to provide a lower rotational speed and higher torque for the DVD-RAM discs, the rotational speed required for high speed playback for CD-ROM discs and DVD-ROM discs is obtained. I do not lose. In this case, these two requirements cannot be provided by one motor.

Japanese Laid-Open Patent Publication No. 10-127086 discloses a technique for varying a torque constant of a motor by offsetting a current translocation timing from a normal timing with respect to an electric current flowing in a stator coil of the motor. This technique will be described with reference to FIG.

9 shows the structure of a conventional control device 400 for a brushless motor. The control device 400 includes an AC power supply 111, a rectifying smoothing circuit 112, a switching power supply 113 for outputting a DC voltage VM, a drive control circuit 114 for receiving a DC voltage VM, and a pulse width. Modulation circuit 115, rotor position detectors 108U, 108V, 108W, and DC motor 123.

The drive control circuit 114 provides a differential amplifier 116, 3 for removing noise components from the three phase output signals HU ', HV', HW 'from the rotor position detectors 108U, 108V, 108W. Three-phase output signals HU ', input to the comparators 117U, 117V, and 117W and the comparators 117U, 117V, and 117W for comparing the phase output signals HU', HV ', and HW', respectively. Amplifiers amplifying one of the two output signals of HV ', HW') (120U, 120V, 120W), logic circuit 118, current switching circuit 119, frequency / voltage converter (F / V converter) 121, and amplification factor variable 122U, 122V, 122W.

Here, each of the amplifiers 120U, 120V, 120W has an amplification factor K. The comparator 117U compares the multiplication signal HU1 obtained by multiplying the U-phase output signal HU 'from the differential amplifier 116 by the amplification factor K with the V-phase output signal HV', and comparing the signal HU2. ) The comparator 117V compares the multiplication signal HV1 obtained by multiplying the V-phase output signal HV 'from the differential amplifier 116 by the amplification factor K with the W-phase output signal HW', and compares the comparison signal HV2. ) The comparator 117W compares the multiplication signal HW1 obtained by multiplying the W-phase output signal HW 'from the differential amplifier 116 by the amplification factor K with the U-phase output signal HU' and comparing the signal HW2. )

The comparison signals HU2, HV2, HW2 are input to the logic circuit 118. The logic circuit 118 outputs the positive (N-pole) output signals HUU, HVU, HWU on the U-, V-, and W- phases to the current switching circuit 119. At the same time, logic circuit 118 outputs negative (S-pole) output signals HUL, HVL, HWL on U-, V- and W- phases to current switching circuit 119.

The current switching circuit 119 turns on the switching power devices TRU1, TRV1, and TRW1 through the U-, V-, and W-phase anodes, and turns on the switching power devices through the U-, V-, and W-phase cathodes. Turn on (TRU2, TRV2, TRW2). Accordingly, the current switching circuit 119 sequentially provides the DC voltage VM to the three phases 107U, 107V, and 107W of the DC motor 123.

The F / V converter 121 converts the output from the differential amplifier 116 into a voltage signal. The amplification factor variable 122U, 122V, 122W varies the amplification factor K of the amplifiers 120U, 120V, 120W according to the output from the F / V converter 121.

By the above-described structure, when one of the two signals input to each of the comparators 117U, 117V, 117W is amplified by the amplifiers 120U, 120V, 120W, respectively, with an amplification factor k> 1, The lead angle Δθ is given to the three phases 107U 107V, 107W of the DC motor 123. The lead angle Δθ is set to an optimal value according to the rotational speed of the rotor assembly by the function of the F / V converter 121.

The above-mentioned control apparatus 400 for a brushless motor has the following problem.

When a large lead angle is given to a brushless motor (eg, DC motor 123), the torque ripple of the brushless motor is increased, thereby increasing unnecessary vibration of the control device 400. This makes it difficult to apply the control device 400 to precision devices susceptible to vibration. The magnitude of vibrations includes variations in vibration adding forces that occur due to individual variations between brushless motors and variations in vibration transfer characteristics of the entire control device 400 associated with variations in vibration additive forces. The factors are combined and determined by this. In order to limit the magnitude of the unnecessary vibration to below all specified factors, it is necessary to limit the adjustable lead angle range to a narrow range. Accordingly, the characteristics of the motor cannot be significantly changed. When a large lead angle is given to the brushless motor, another problem arises that the reliability of the control device 400 for limiting the vibration level below the specified level is insufficient.

The level at which vibration of a disk device using a brushless motor is allowed depends on whether a high recording density information disc such as a DVD disc or a low recording density information disc such as a CD-ROM disc is used. As a result, the range of the lead angle that can be set for the brushless motor is changed. The level at which vibration of the disk device using the brushless motor is allowed also depends on whether a playback-only DVD-ROM disk or a recordable DVD-RAM disk is used. The range of lead angles that can be set for a brushless motor varies. This change in permissible vibration level has not been considered conventionally.

The disk device described above is complicated in the control of the variable lead angles, making it difficult to simplify the motor control device. This is because the lead angle is set in accordance with the rotational speed. Such a system requires components including an F / V converter, and also needs to constantly monitor the rotational speed to update the lead angle. As a result, a circuit used only for setting the read angle is required, or in order to update the read angle when the CPU, DSP, or the like is used, frequent use of interrupts is required.

When it is necessary to control the actual rotational speed so that the target rotational speed changes frequently and follows the target rotational speed, the amplitude of the drive current needs to be controlled while changing the lead angle. The control operation is complicated because the two parameters must be changed at the same time.

Due to the amplitude variation and the waveform distortion of the outputs between the outputs from the three rotor position detectors 108U, 108V, 108W, the setting angle of the lead angle is lowered. When the outputs from the rotor position detectors 108U, 108V, 108W have ideal sinusoidal signals having the same amplitudes between each other, the correct lead angle can be set for the following reasons. By amplifying one of the two outputs by a constant value and combining the amplified output with the other output, a sinusoidal signal having a phase shifted by a desired amount can be formed. In practice, however, the outputs from the three rotor position detectors 108U, 108V, 108W are caused by the individual fluctuations between the rotor position detectors (e.g. Hall elements) or due to temperature. It has different amplitudes due to the change in the properties of the position detectors. When these signals with different amplitudes are used, the lead angle between U-, V-, W- phases is different. This causes an error in the lead angle between the phases. Also, the outputs from the rotational position detectors 108U, 108V, 108W do not themselves have pure sinusoidal waveforms. For example, due to variations in the magnetization characteristic of the rotor magnet, the waveforms of the outputs are sometimes distorted by the large harmonic component added to the output. In this state, the relationship between the amplification factor K and the lead angle is significantly different from the relationship when the pure sine wave is obtained. This deteriorates the setting accuracy of the lead angle.

It is not necessary that the lead angle can be arbitrarily controlled. It is possible to preset the lead angle as a factor with respect to the rotational speed of the motor. This factor generally simply increases with increasing motor rotational speed (∝ hole output frequency). This factor is very easily realized using, for example, differential circuits. Japanese Laid-Open Utility Model Publication No. 62-48198 discloses a technique for setting a lead angle in accordance with the rotational speed of a two-phase pulse motor using a differential circuit. This technique is described with reference to FIG.

10 illustrates the structure of a conventional pulse motor driving circuit 500. The pulse motor driving circuit 500 is connected to the two-phase exciting pulse motor 131 and the pulse motor 131 to generate an output signal Sf according to the rotation angle θ of the pulse motor 131. Angle calculation circuit 133 for calculating the rotation angle θm of the pulse motor 131 with respect to the magnetic pole based on the resolution encoder 132 and the output Sf of the encoder 132, the rotation angle Factor generating circuit 134 for generating sinusoidal signals Ss and Sc having a phase difference of 90 ° with respect to (θm), sinusoidal signals Ss and Sc according to the amplitude of control signal S1 Multipliers 135, 136, phase read circuits 139, 140, and power amplifiers 137, 138 for varying the amplitudes of the power amplifier. Outputs IA, IB of power amplifiers 137, 138 are provided to armature coils (not shown) of pulse motor 131, respectively.

11 shows the structure of the phase read circuits 139 and 140. The phase lead circuits 39 and 140 shown in FIG. 11 include an amplifier 141, resistors 142 and 143, and a capacitor 144, respectively. The phase read amount of the phase read circuits 139 and 140 is selected to compensate for the phase delay of the magnetic flux with respect to the frequency change of the excitation current.

The position of the rotor (not shown) of the pulse motor 131 is detected by the encoder 132 and the angle calculation circuit 133. Excitation currents IA and IB corresponding to the position are provided to the armature coils, respectively.

The amplitudes of the outputs Ss and Sc from the factor generator circuit 134 are represented by equation (1).

Ss = sin (θm + π / 2)

Sc = cos (θm + π / 2) (1)

When the amplitude of the control signal Si supplied to the armature coils of the pulse motor 131 is Io, the magnitudes of the exciting currents IA and IB are represented by equation (2).

IA = Io * sin (θm + π / 2)

IB = Io * cos (θm + π / 2) (2)

As is apparent from equation (2), the exciting currents IA, IB supplied to the respective armature coils have a phase difference of 90 °, and their sum (vector synthesis) is constant. Therefore, the rotor generates a uniformly constant torque. The magnitude of the torque is proportional to the amplitude Io of the control signal Si. Therefore, when the load is zero, the pulse motor 131 stops if Io is zero. When Io increases, the pulse motor 131 rotates at a speed according to Io.

The electrical angle of the combined current of the excitation currents IA, IB has a phase difference of 90 ° with respect to the mechanical angle (rotation angle θ) of the rotor of the pulse motor 131. Therefore, maximum torque can be generated.

However, when the pulse motor 131 enters the high speed operating region and the frequency of the excitation currents IA and IB increases, the phase of the magnetic flux generated with respect to the drive current is delayed due to iron loss such as magnetic path.

To avoid this, phase read circuits 139 and 140 are provided in the excitation circuit. When the pulse motor 131 enters the high speed operating region and thus the frequency of the excitation currents IA and IB increases, the phases of the excitation currents IA and IB are driven by the phase read circuits 139 and 140. Leads. Thus, the phase delay of the magnetic flux caused by the iron loss in the gyro can be compensated by the read phase of the exciting currents IA and IB. Therefore, the phase difference between the machine angle and the magnetic flux of the rotation is maintained so that the torque reduction generated can be prevented.

The pulse motor driving circuit 500 has the following problem.

It is assumed that the pulse motor driving circuit 500 is applied to the disk apparatus, and the current timing for the current flowing in the stator coil of the motor is offset from the normal timing in order to vary the torque constant of the motor. In this state, when the maximum high rotation speed required for high speed playback of CD-ROM discs and DVD-ROM discs is to be realized, the phase is excessively read even when the DVD-RAM discs are rotated at low speed for a high-speed search operation. , The torque is reduced.

This is described in detail with reference to FIG. Fig. 12 shows the relationship between the phase lead angle and the rotational speed obtained by the phase lead circuit. Characteristic 28 shown in Fig. 12 shows the relationship between the rotational speed and the phase lead angle when the constant of the phase lead circuit is set to be suitable for high speed reproduction of CD-ROM discs. The characteristic 28 is, for example, in the phase lead circuits 139 and 140 that the value R1 of the resistor 143 is set to a relatively small value, the value of the capacitor 144 is set to 0.01 mV, and the resistor 142 is set to be smaller. It is obtained when the value of R2 is set to 21 ㏀.

The main purpose of this setting is to make the lead angle larger than necessary to compensate for the current delay caused by the inductance component of the coil, to reduce the torque constant of the motor by the weak electric field effect, and to improve the maximum rotational speed of the motor. It is to limit the generation of back EMF. Therefore, using a disc motor having a no-load rotational speed of 6300 rpm, a starting torque of 190 gcm and a torque constant of 0.17 gcm / mA, a rotational speed of 9000 rpm necessary for reproducing about 42 times the speed of the CD-ROM disc can be obtained.

However, characteristic 28 results in a large phase lead angle of about 10 ° to 23 ° with respect to the rotation range of DVD-RAM discs of 1370 to 3250 rpm. Since the torque constant is reduced by the weak electric field effect, the search time is undesirably delayed in the DVD-RAM disc requiring the rotational speed change during the search operation for performing the ZCLV control.

Characteristic 27 shown in Fig. 12 shows the relationship between the phase lead angle and the rotational speed suitable for recording or reproducing information on DVD-RAM discs. The characteristic 27 is obtained when setting R2 to a relatively small value, setting the value of the capacitor 144 to 0.01 mW and setting R1 to 6 mW. The main purpose of this setup is to increase the lead angle and maximize the torque constant of the motor to fully compensate for the current delay caused by the inductance component of the coil.

Accordingly, the time for the search operation of the DVD-RAM disk performed by the same disk motor can be shortened. However, according to characteristic 27, there is a maximum rotational speed as low as about 5700 rpm, which is not sufficient for high speed reproduction of information on CD-ROM discs.

As described above, the conditions for fast reproduction and the conditions for reducing the seek time conflict with each other as a single circuit integer setting. For example, it is ideal to realize the characteristic 29 shown in Fig. 12, which rapidly increases the lead angle when the rotational speed of the motor reaches the specified level. However, it is difficult to realize the characteristic 29 with the phase lead circuits 139 and 140 shown in FIG.

SUMMARY OF THE INVENTION The present invention for solving the above problems provides a control device for a brushless motor and a disk device using the same, which are highly reliable for vibration, can easily perform motor control, and have a high setting accuracy of a lead angle. For the purpose of

The present invention realizes both a high speed search operation for ZCLV control and a high speed playback operation of a CD-ROM disc and a DVD-ROM disc in one motor and a simple structure when recording or reproducing information on a DVD-RAM disc. An object of the present invention is to provide a disk device.

1 shows an optical disk device according to a first embodiment of the present invention.

2 shows an optical disk device according to a second embodiment of the present invention.

3 shows a phase read circuit in a second embodiment of the present invention;

4 shows an optical disk device according to a third embodiment of the present invention.

5 shows a phase read circuit in a third embodiment of the present invention;

Fig. 6 is a diagram showing the phase relationship between signals received and output by the read angle correction means in the third embodiment of the present invention.

7 shows a phase read circuit in a third embodiment of the present invention;

8 shows the present invention

Diagram showing a phase lead circuit in a third embodiment.

9 is a view showing a conventional brushless motor control device.

10 shows a conventional pulse motor driving circuit.

11 shows a conventional phase lead circuit.

Fig. 12 is a diagram showing the relationship between the rotational speed and the lead angle obtained by the phase lead circuit.

A brushless motor control apparatus according to the present invention includes a brushless motor including a rotor magnet and a stator coil; Rotor position detecting means for detecting a plurality of magnetic pole positions of the rotor magnet; Vibration detection means for detecting unnecessary vibration of the brushless motor when the brushless motor is rotating; Lead angle setting means for setting the size of the lead angle such that the first output from the vibration detecting means does not exceed a predetermined allowable value; And lead angle correction means for providing a lead angle from the rotor position detecting means to the third output in accordance with the second output from the lead angle setting means to generate a current timing of the drive current to the stator coils. .

The disk apparatus according to the present invention includes the brushless motor control apparatus described above. The brushless motor rotates the information disc. The disk apparatus includes a head for recording information on an information disk and reproducing the information from the information disk; And head control means for controlling the head to be on the track of the information disc. The vibration detecting means detects the magnitude of unnecessary vibration from the control error between the head and the track.

A disk apparatus according to the present invention, which makes it possible to replace a plurality of kinds of information disks having different recording formats, comprising a rotor magnet and a stator coil, wherein at least one information mounted to the disk apparatus among the plurality of kinds of information disks is provided. Brushless motor for rotating the disk; Rotor position detecting means for detecting a plurality of magnetic pole positions of the rotor magnet; Discriminating means for discriminating according to a format of the at least one information disk; Lead angle setting means for setting the size of the lead angle using the first output from the discriminating means; And lead angle correction means for providing a lead angle from the rotor position detecting means to the third output in accordance with the second output from the lead angle setting means to generate a current timing of the drive current to the stator coils. .

The disk apparatus according to the present invention may further include vibration detecting means for detecting unnecessary vibration of the brushless motor when the brushless motor is rotating. The lead angle setting means may set the magnitude of the allowable value of unnecessary vibration in accordance with the first output, and set the magnitude of the lead angle so that the fourth output from the vibration detection means does not exceed the allowable value.

Among the plurality of types of information discs, a second information disc having a recording density lower than the recording density of at least the first information disc and the first information disc may be replaceably mounted. When the discriminating means detects the presence of the first information disk, the lead angle setting means may set the lead angle to be smaller than when the discriminating means detects the presence of the second information disk.

At least one information disk is driven by ZCLV control, and the lead angle can be set to 0 degrees.

The at least one information disk can be driven by CAV control.

Among the plurality of types of information discs, at least recording and reproduction information discs that can be used for recording and reproduction and reproduction only information discs that can be used for reproduction can be interchangeably mounted. When the discriminating means detects that there is a recording / playing disc, the lead angle setting means can set the lead angle to be smaller than when the discriminating means detects that there is a read-only information disc.

A brushless motor control apparatus according to the present invention includes a brushless motor including a rotor magnet and a stator coil; Rotor position detecting means for detecting a plurality of magnetic pole positions of the rotor magnet; In order to generate current timing of the drive current to the stator coils, lead angle correction means for providing a lead angle having a variable amount to the output from the rotor position detecting means is included. The rotor position detecting means generates a plurality of detection signals having different phases from each other. The read angle correction means includes normalizing means for converting a plurality of detection signals into a plurality of sinusoidal signals having a predetermined amplitude, and combining means for synthesizing the plurality of sinusoidal signals at a predetermined ratio.

The normalizing means may include a low pass filter through which a signal in a frequency range corresponding to a rotation frequency of the brushless motor is passed among the plurality of detection signals.

The normalization means may comprise an AGC circuit.

The disk apparatus according to the present invention includes the brushless motor control apparatus described above. The brushless motor rotates the information disc. The disk apparatus includes a head for recording information on an information disk and reproducing the information from the information disk; And head control means for controlling the head to be on the track of the information disc.

A disk apparatus according to the present invention, which makes it possible to interchangeably mount a plurality of types of information discs having different recording formats, comprising a rotor magnet and a stator coil, which is free of rotating at least one of the plurality of types of information discs. Brush motor; Rotor position detecting means for detecting a plurality of magnetic pole positions of the rotor magnet; Lead angle correction means for providing a lead angle having a variable amount to a first output from the rotor position detecting means to generate a current timing of a drive current to the stator coils; And discriminating means for discriminating according to a recording format of at least one information disk mounted in the disk apparatus. The lead angle correction means includes a plurality of differential circuits, and the circuit constant of each of the plurality of differential circuits is changed using the second output from the discriminating means, thus the relationship between the rotational speed of the brushless motor and the lead angle Is changed.

Each of the plurality of differential circuits includes a plurality of resistors; Capacitors; And at least one transistor connected in parallel to at least one of the plurality of resistors. The circuit constant is changed by switching on and off states of the at least one transistor.

A disk apparatus according to the present invention, which makes it possible to interchangeably mount a plurality of types of information discs having different recording formats, comprising a rotor magnet and a stator coil, which is free of rotating at least one of the plurality of types of information discs. Brush motor; Rotor position detecting means for detecting a plurality of magnetic pole positions of the rotor magnet; Lead angle correction means for providing a lead angle having a variable amount to a first output from the rotor position detecting means to generate a current timing of a drive current to the stator coils; And discriminating means for discriminating according to a recording format of at least one information disk mounted in the disk apparatus. The lead angle correcting means includes a plurality of integrating circuits, and the circuit constant of each of the plurality of integrating circuits is changed by using a second output from the discriminating means, and thus the relationship between the rotational speed of the brushless motor and the lead angle Is changed.

Each of the plurality of integrating circuits comprises: a plurality of resistors; Capacitors; And at least one transistor connected in parallel to at least one of the plurality of resistors. The circuit constant is changed by switching on and off states of the at least one transistor.

The lead angle correction means further includes a plurality of inverters, and a third output obtained by inverting the first output by one of the plurality of inverters is input to at least one of the plurality of resistors.

The lead angle correction means may further include a plurality of amplifiers. The first output includes a first signal and a second signal offset by a predetermined angle with respect to each other. The first signal is input to a first amplifier of the plurality of amplifiers. The second signal is input to at least one of the plurality of resistors of the first integration circuit corresponding to the first amplifier among the plurality of integration circuits.

A predetermined lead angle may be provided to the first output in advance.

The stator coil includes N phases driven by driving currents offset by a predetermined angle with respect to each other. The first output includes N signals offset by an angle with respect to each other. The read angle correction means generates current timing of drive currents in the stator coil using n signals out of N signals. N is an integer greater than or equal to 2, and n is an integer greater than or equal to 2 but less than N.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Example 1)

1 is a schematic structural diagram of a disk device 100 according to a first embodiment of the present invention. The disk apparatus 100 makes it possible to replace and detachably mount a plurality of types of optical disks 1 having different recording formats by a loading mechanism (not shown). Examples of the optical discs 1 include DVD-ROM discs and DVD-RAMs having a high recording density (for example, a recording capacity of 2.6 GB or 4.7 GB and a thickness of 0.6 mm), and a low recording density (CD Including CD-ROMs, for example, a CD-ROM having a recording capacity of 650 MB and a thickness of 1.2 mm). DVD-ROM disks and CD-ROM disks may be in a form not accommodated in the cartridge 2, and DVD-RAM disks may be in a form accommodated in the cartridge 2. Regardless of the recording format, the optical discs 1 are common in that they have a recording track, and in that information is recorded along the recording track or information is recorded along the recording track.

The disk apparatus 100 includes a cartridge detecting means 3, a turntable 4, a brushless motor 5, an optical head 6, a guide shaft 7, a head control means 8, and a vibration level detecting means 9. ), Disc discrimination means 10, rotor position detecting means 20, and brushless motor control means 33. The brushless motor 5 is used as a disk motor. The brushless motor control means 33 includes and controls the lead angle setting means 11, the brushless motor driver 32, and the lead angle correction means 23. The lead angle correction means 23 includes a normalizing means 24 and a combining means 27. The synthesizing means 27 comprises coefficient setting means 28.

The cartridge detecting means 3 comprises a micro switch (not shown) provided at the position of the disk apparatus 100 in contact with the cartridge 2 for the DVD-RAM disk. Accordingly, the cartridge detecting means 3 detects whether or not the DVD-RAM disk is accommodated in the cartridge 2. The turntable 4 inserts the optical disk 1 mounted therein into the disk apparatus 5 by the loading mechanism, and the brushless motor 5 rotates the turntable 4. The brushless motor 5 is an external rotor type three phase DC brushless motor, for example. Although not shown, the brushless motor 5 may include a 12-pole magnetized rotating magnet and a 9-pole three-phase stator coil, and may be driven by the brushless motor driver 32 with a power supply of 5V or 12V. The structure described later is driven by a 5V power supply. The brushless motor 5 includes a coil or the like designed to have a torque characteristic sufficient to realize the maximum rated rotational speed of the DVD-RAM disc at 3250 rpm when the lead angle is 0 °, as will be described later. When the lead angle is 0 °, the maximum rotational speed of the no-load brushless motor 5 may be about 6500 rpm. The optical head 6 is movably supported in the radial direction of the disk along the guide shaft by a head feed motor (not shown) for recording or reproducing information on the optical disk 1.

The head control means 8 performs a process such as demodulation or error correction to convert this information into a valid data stream with respect to the information read from the optical disc 1 by the optical head 6, and from the optical head 6 The light beam is controlled so as to be on the desired recording track of the optical disc 1. In order to control the light beam to be on the recording track, two kinds of control are performed. One is focusing control such that the focus of the light beam is on the recording surface comprising the recording track. The other is tracking control which causes the light beam to follow the recording track. After these kinds of control, the control error is output to the vibration level detecting means as the focusing error signal FE and the tracking error signal TE.

The vibration level detecting means 9 receives the track cross signal during the search operation, the signal of the address portion of the DVD-RAM disc, and the like from the focusing error signal FE and the tracking error signal TE received from the head control means 8. Remove Subsequently, the vibration level detecting means 9 detects amplitudes of the FE signal and the TE signal representing only the error component after the light beam is controlled to be on the recording track. The vibration level detecting means 9 outputs the detection results to the read angle setting means 11 as vibration levels FEamp and TEamp.

The disk discriminating means 10 receives the output from the cartridge detecting means 3 and the output from the head control means 8 to determine the type of the optical disk 1 inserted into the disk apparatus 100. Specifically, the disc discrimination means 10 determines whether or not the optical disc 1 inserted in the disc apparatus 100 is accommodated in the cartridge based on the output from the cartridge detecting means 3. Next, the disc discrimination means 10 determines whether the thickness of the disc is 0.6 mm or 1.2 mm based on the output pattern of the head control means 8 when the light beam is focused. Taking these results into consideration comprehensively, the disc discrimination means 10 is as follows: when the disc is 1.2 mm thick, the disc is a CD-ROM disc, and when the disc is 0.6 mm thick but is not contained in the cartridge. The disc is a DVD-ROM disc, and when the disc is 0.6 mm thick and contained in the cartridge, the disc is temporarily determined to be a DVD-RAM disc. Based on the temporary determination result, the information is actually read from the optical disc 1. Subsequently, the disc type is determined based on the disc type data described in the control track of the optical disc 1 read from the optical disc 1. The determination result of the disc discrimination means 10 is output to the read angle setting means 11.

The lead angle setting means 11 stores in advance the pattern used to set the lead angle for each type of optical disc 1. For example, the lead angle setting means 11 has an optimum value determined experimentally, for example, a lead angle of 40 ° for driving a CD-ROM disc at a maximum rotational speed of 5100 rpm, and a maximum rotational speed of 3600 rpm. 20 ° lead angle for driving a DVD-ROM disc, and 0 ° lead angle for a DVD-RAM. When driving CD-ROM discs and DVD-ROM discs at low rotational speeds of 3250 rpm or less, the lead angle is set to 0 °. In DVD-ROM discs and DVD-RAM discs having higher recording densities, the read angle range is set narrower than that of CD-ROM discs having low recording densities. In a DVD-RAM disc that can be used for recording and reproducing, the read angle range is set narrower than that of a DVD-ROM disc dedicated to reproduction. This is to reduce the influence of vibration caused by torque ripple of the brushless motor 5 on the optical disc 1 when the optical disc 1 has a high recording density. The setting of the lead angle is described in detail below with respect to the operation.

When the detection result of the disc discrimination means 10 is received, the lead angle setting means 11 outputs the lead angle according to the disc type to the coefficient setting means 28 of the synthesizing means 27. The lead angle setting means 11 stores in advance different permissible vibration levels FEalw and TEalw for different kinds of optical discs 1. For example, in the case of a CD-ROM disc, the lead angle setting means 11 sets the FE voltage corresponding to the focused deviation amount of 0.6 mu m as FEalw, and the TE voltage corresponding to the track deviation amount of 0.06 mu m as the TEalw. Set it. Similarly, in the case of a DVD-ROM disc, the lead angle setting means 11 sets the FE voltage corresponding to the focus deviation amount of 0.3 mu m as FEalw and the TE voltage corresponding to the track deviation amount of 0.03 mu m as the TEalw. do. In the case of a DVD-ROM disc, the lead angle setting means 11 sets the FE voltage corresponding to the focus deviation amount of 0.2 m as the FEalw and the TE voltage corresponding to the track deviation amount of 0.015 m as the TEalw.

Upon reception of the detection result of the disc discrimination means 10, the lead angle setting means 11 sets the allowable vibration levels FEalw and TEalw according to the type of the optical disc 1. When the brushless motor 5 is rotating, the lead angle setting means 11 always sets the allowable vibration levels FEalw and TEalw from the vibration level detection means 9 and the vibration levels FEalw and TEalw. Compare with When at least one of the vibration levels FEalw and TEalw exceeds the allowable vibration levels FEalw and TEalw, the lead angle setting means 11 reduces the lead angle. This operation is repeated until both vibration levels FEalw and TEalw are below the allowable vibration levels FEalw and TEalw, respectively, or until the lead angle is zero degrees.

The rotor position detecting means 20 comprises three Hall elements 21U, 21V, 21W for detecting the magnetic poles of the rotor magnet of the brushless motor 5, and between the positive and negative voltages of the respective Hall elements. Hall amplifiers 22U, 22V, 22W to achieve the difference. Hall elements 21U, 21V, 21W are attached at predetermined positions in the circumferential direction of the rotating magnet which is one third of the magnetization cycle away. The outputs from the Hall elements 21U, 21V, 21W are reduced in phase by the Hall amplifiers 22U, 22V, 22W, and the three phase position detection signals HU, HV are out of phase by 120 ° with respect to each other. , HW) is output to the normalization means 24.

Normalization means 24 include low pass filters 25U, 25V, 25W, and AGC (automatic gain control) circuits 26U, 26V, 26W. The normalization means 24 reduces each harmonic component of the position detection signals HU, HV, HW from the position detection means 20, and the amplitude of each position detection signals HU, HV, HW. Adjust it. As a result, the normalization means 24 output substantially sinusoidal signals SU, SV, SW having a uniform amplitude. The cutoff frequency of each low pass filter 25U, 25V, 25W is variably set by multiplying the rotation frequency of the optical disc 1 by a predetermined coefficient. In this embodiment, the coefficient causes the cutoff frequency to be 72 Hz, for example, when the disk rotation is 3600 rmp (rotation frequency: 60 Hz), and cuts off when the disk rotation speed is 5100 rpm (rotation frequency: 85 Hz). The frequency is set to 1.2 to be 102 Hz. The AGC circuits 26U, 26V, 26W generally perform gain control such that the amplitudes of the sinusoidal signals SU, SV, SW become a prescribed value. The prescribed value is set to be within the rated range of the input to the brushless motor driver 32 described later, and is the same in the AGC circuits 26U, 26V, 26W.

The synthesizing means 27 receives the lead angle θ (degrees) output from the lead angle setting means 11, and sinusoidal signals SU, SV input from the normalization means 24 according to the following equation (3). , SW) are combined to generate outputs KU, KV, KW. The outputs KU, KV, KW generated in this way have the same amplitude as the sinusoidal signals SU, SV, SW and have an angle θ with respect to the phases of the signals SU, SV, SW. Have as many phases as read.

KU = α * SU-β * SV

KV = α * SV-β * SW

KW = α * SW-β * SU (3)

Here, α and β are integers and are obtained from the relations represented by equation (4) of the lead angle θ (degrees).

α = cosθ-(1 / √3) * sinθ (4)

β = cos (60-θ)-(1 / √3) * sin (60-θ)

Specifically, the synthesizing means 27 includes coefficient setting means 28, multipliers 29U, 29V, 29W, multipliers 30U, 30V, 30W, and subtractors 31U, 31V, 31W. The coefficient setting means 28 previously stores the relations represented by the formula (4) in the table, and outputs coefficients α and β based on an input having a value corresponding to the lead angle θ.

Multipliers 29U, 29V, 29W each multiply outputs SU, SV, SW from normalization means 25 by α. Multipliers 30U, 30V, 30W each multiply the outputs SU, SV, SW from each means 25 by β. Each of the multipliers 29U, 29V, 29W, 30U, 30V, 30W includes a combination of an amplification variable and an amplifier. Subtractors 31U, 31V, 31W are differential amplifiers for obtaining the differences between the outputs from multipliers 29U, 29V, 29W and the outputs from multipliers 30U, 30V, 30W, respectively.

The three-phase full wave brushless motor driver 32 of the 180 ° or 210 ° PWM drive system is brushless in synchronization with the received three-phase position detection signals (ie, outputs KU, KV, KW). A drive signal for driving the motor 5 is generated.

The disk device having the above-described structure operates as follows.

When the power of the disk apparatus 100 is turned on or when the optical disk 1 is loaded by the loading mechanism, the disk discriminating means 10 determines the type of disk.

First, the operation of the disk device 100 when the disk is a CD-ROM disk will be described. When the disc discrimination means 10 detects that the disc is a CD-ROM disc, the brushless motor control means 33 accelerates the brushless motor 5 at the maximum rotational speed of 5100 rpm in a two-step acceleration process as follows. Let's do it.

In the first step, the target rotational speed of the brushless motor 5 is set to 3250 rpm. At the same time, the lead angle setting means 11 sets the lead angle to 0 degrees. At this time, the lead angle correction means 23 does not substantially correct the lead angle. The brushless motor driver 32 conducts a drive current in the same phase as the output from the rotor position detecting means 20 to accelerate the brushless motor 5.

When the rotational speed of the brushless motor 5 reaches 3250 rpm, a third step is started. The brushless motor control means 33 sets the target rotational speed of the brushless motor 5 to 5100 rpm. The lead angle setting means 11 outputs a set value of a lead angle of 40 ° to the coefficient setting means 28. Based on equation (4), the coefficient setting means 28 outputs α = 0.395 and β = 0.742, sets the coefficients of the multipliers 29U, 29V, 29W to the α value and the multipliers 30U, 30V, 30W. ) Is set to the β value. The outputs HU, HV, HW from the rotor position detecting means 20 each have a harmonic component reduced by the normalizing means 24 and have sinusoidal signals SU, SV having a uniform amplitude. , SW). Sinusoidal signals SU, SV, SW are converted by synthesizing means 27 into outputs KU, KV, KW provided a lead angle of 40 °. Based on the outputs KU, KV, KW, the brushless motor driver 32 conducts a current of the drive current. Thus, the excitation delay caused by the inductance component of the stator coil (not shown) is corrected. In combination with the effect of back EMF reduced by the weak electric field, the correction widens the range of rotational speeds of the motor, so that the brushless motor 5 is accelerated to a target rotational speed of 5100 rpm.

In this state, the head control means 8 controls the light beam so as to be on the desired recording track of the optical disc 1 (i.e., CD-ROM disc), and the oscillation level detection means 9 provides a focusing error signal FE and Output a tracking error signal (TE). The vibration level detecting means 9 detects amplitudes of the focus error signal FE and the tracking error signal TE, and outputs the detected amplitudes to the read angle setting means 11 as vibration levels FEamp and TEamp. . The lead angle setting means 11 compares the received vibration levels FEamp and TEamp with the allowable vibration levels FEalw and TEalw. When the vibration level FEamp or TEamp is higher than the allowable vibration levels FEalw and TEalw, the lead angle is reduced until the vibration levels FEamp and TEamp are below the allowable vibration levels FEalw and TEalw. do.

Due to the structure described above, even when the unnecessary vibration exceeds the allowable vibration levels FEalw and TEalw, torque ripple caused by the lead angle in accordance with the individual characteristic variation of the brushless motor 5 and the optical disc 1 Due to this, this is detected without failure and the lead angle is reduced to limit the vibration level to be below the acceptable vibration level. Accordingly, the disk device 100 having a high reliability of data reproduction can be provided.

When the lead angle is reduced as described above, the rotation speed of the brushless motor 5 is reduced to be lower than the target rotation speed of 5100 rpm. However, this only causes a slight adverse effect that the speed of reading information from the optical disc 1 is reduced. The reliability of the entire system of the disk device 100 is not lowered.

In this embodiment, the vibration level detecting means 9 detects unnecessary vibration, and the lead angle setting means 11 sets the magnitude of the lead angle in accordance with the detected unnecessary vibration. Thus, in spite of the individual variations of the brushless motor 5 and the optical disc 1, the lead angle can be effectively set within the allowable range, and unnecessary vibration can be reliably limited to below the prescribed level. Therefore, the reliability of the disk device 100 can be guaranteed.

The brushless motor control means 33 performs CAV (right angle speed) control on the CD-ROM disc in order to maintain the rotational speed of the brushless motor 5 regardless of the speed of the search operation. Therefore, it is not necessary to change the setting of the lead angle except when the disk device 100 starts to operate. Therefore, the lead angle can be simply set as described above.

Even when the lead angle is reduced to 0 °, when the vibration level FEamp or TEamp is still higher than the allowable vibration levels, the brushless motor control means 33 sets the target rotational speed of the brushless motor 5 at a low level ( For example, it sets to 2500 rpm) which is about half of 5100 rpm, and the lead angle setting means 11 sets the lead angle to 0 degrees. Subsequently, the brushless motor 5 starts operation again.

Next, the operation of the disk apparatus 100 when the disk discriminating means 10 detects that the disk is a DVD-ROM disk will be described. In this case, the brushless motor control means 33 accelerates the brushless motor 5 at the maximum speed of 3600 rpm in a two-step acceleration process in the same manner as in the case of the CD-ROM disc.

In the first step, the brushless motor control means 33 sets the target rotational speed of the brushless motor 5 to be 3250 rpm. At the same time, the lead angle setting means 11 sets the lead angle to 0 degrees. When the rotational speed of the brushless motor 5 has reached 3250 rpm, the second stage is started. The brushless motor control means 33 sets the target rotational speed of the brushless motor 5 to 3600 rpm. The lead angle setting means 11 outputs a lead angle setting value of 20 ° to the coefficient setting means 26. The coefficient setting means 28 sets α = 0.742 as the coefficient of the multipliers 29U, 29V, 29W and β = 0.395 as the coefficient of the multipliers 30U, 30V, 30W. The outputs HU, HV, HW from the rotor position detecting means 20 are converted into outputs KU, JV, JW provided at a lead angle of 20 °. The lead angle of 20 ° is determined as a value for correcting the excitation delay by the inductance component of the stator coil (not shown), and has substantially no influence as a weak electric current. Therefore, torque ripple does not increase significantly. In this setting, the brushless motor 5 is accelerated to a target rotational speed of 3600 rpm.

In this state, the head control means 8 controls such that there is a light beam on a desired recording track of the optical disc 1 (i.e., DVD-ROM disc), and the focus error signal FE and the tracking error signal TE are controlled. Output to the vibration level detecting means (9). The vibration level detecting means 9 detects the amplitude of the focus error signal FE and the amplitude of the tracking error signal TE, and then transmits the detected amplitudes to the lead angle setting means 11 to the vibration levels FEamp and TEamp. Output as. The lead angle setting means 11 compares the received vibration levels FEamp and TEamp with the allowable vibration levels FEalw and TEalw. When the vibration level FEamp or TEamp is higher than the allowable vibration levels FEalw and TEalw, the lead angle is reduced until the vibration levels FEamp and TEamp are below the allowable vibration levels FEalw and TEalw. do.

When a DVD-ROM disc having a high recording density is used, the lead angle is initially set small and the allowable vibration level is set lower than when a CD-ROM disk having a low recording density is used. Thus, the highest possible performance can be obtained from the disk device 100 for different types of optical disks 1 while ensuring the reliability of the disk device 100 against unnecessary vibrations.

In this embodiment, the lead angle is varied in accordance with the output from the vibration level detecting means 9. The present invention provides an effect not provided by the prior art even when the disk apparatus 100 does not include the vibration level detecting means 9. Specifically, as described above, the present invention provides a structure for initially setting the read angle of the first disc having a high recording density to be smaller than that of the second disc having a low recording density. This structure itself leads to the highest possible performance of the disk device 100 for both the second disk having high durability against vibration and the first disk having low durability against vibration.

As in the case of the CD-ROM disk, the brushless motor control means 33 performs CAV control on the DVD-ROM disk to maintain the rotational speed of the brushless motor 5 regardless of the speed of the search operation. When the vibration level is still higher than the allowable vibration levels even when the lead angle is reduced to 0 °, the brushless motor control means 33 sets the target rotational speed of the brushless motor 5 at a lower level (for example, 3600). 1800 rpm, which is approximately half the rpm, and the lead angle setting means 11 sets the lead angle to 0 degrees. Subsequently, the brushless motor 5 starts operation again.

Next, the operation of the disk apparatus 100 when the disk discriminating means 10 detects that the disk is a DVD-RAM disk will be described. In this case, the lead angle setting means 11 sets the lead angle to 0 degrees, and the brushless motor 5 is always driven without any correction of the lead angle. The brushless motor control means 33 drives the brushless motor 5 in the zoned constant linear velocity (ZCVL) control. When the optical head 6 is on the innermost position of the DVD-RAM disc, the disc rotation speed is set to 3250 rpm. When the optical disc 6 is on the outermost position of the DVD-RAM disc, the disc rotation speed is set to 1350 rpm. The disk rotational speed can always vary within the range of 3250 rpm to 1350 rpm depending on the position of the optical head 6. As described above, the brushless motor 5 is designed to take some rotational speed range used for the brushless motor 5 to have optimum motor characteristics. Therefore, the time required to change the rotational speed of the disk accompanied by the search operation can be shortened.

The rotation speed of the brushless motor 5 changes frequently, but the control is simple. The reason is that since the lead angle is set to 0 degrees when the DVD-RAM disc is used, it is not necessary to change the setting of the lead angle in the disk apparatus 100.

Also, the lead angle is larger than when information-only discs, such as DVD-ROM discs for playback are used, for example, when information-recording and playback discs, such as DVD-RAM discs that can be used for recording and playback, are used. It is set smaller. Therefore, the highest possible performance can come from the disk apparatus 100 for both the reproduction only disc having high durability against vibration and the recording reproduction disc having low durability against vibration.

As described above, in this embodiment, the vibration level detecting means 9 detects unnecessary vibration, and the lead angle setting means 11 sets the size of the lead angle in accordance with the detected unnecessary vibration. Thus, in spite of individual variations of the brushless motor 5 and the optical disc 1, the lead angle can be effectively set within the allowable range and the unnecessary vibration can be reliably limited to below the prescribed level. Therefore, the reliability of the disk device 100 can be guaranteed.

Since the size of the lead angle is set in accordance with the output from the disc discrimination means 10, an optimal lead angle is set for each of the different kinds of discs having different levels of durability against vibration. Accordingly, the highest possible performance of the disk device 100 can come out for each type of disk. In addition, it is possible to determine not only the type of disk but also whether the disk is a disk of a ZCLV rotation control system or a disk of a CAV rotation control system. Therefore, the lead angle can be simply set using the characteristics of each rotation control system. In this embodiment, the lead angle can be set to a significantly simpler circuit configuration than that by the conventional system of uniformly setting the lead angle according to the rotational speed.

The outputs from the rotor position detecting means 20 are synthesized by the combining means 27 after the amplitudes are equalized and the harmonic components are removed by the normalizing means 24. Therefore, even if the outputs from the rotor position detecting means 20 have variations in amplitudes or distortions in waveforms, these factors do not affect the setting precision of the lead angle on each phase. Accordingly, highly precise correction of the lead angle can be performed.

In this embodiment, the brushless motor driver 32 drives the brushless motor 5 with a power supply voltage of 5 V, and the brushless motor 5 has a coil structure that provides optimum performance under this condition. When the brushless motor driver 32 drives the brushless motor 5 with a power supply voltage of 12 V and the brushless motor 5 is configured to provide optimum performance under these conditions, it leads to the brushless motor 5. By providing an angle, the motor can be rotated at higher speeds. For example, in reproducing information from a CD-ROM disc, a rotation speed of 9000 rpm (more than 42 times speed) or more can be realized.

(Example 2)

2 is a schematic structural diagram of a disk device 200 according to a second embodiment of the present invention.

Use the same reference numerals for the same components discussed earlier. However, in this embodiment, the brushless motor 5 and the brushless motor driver 32 can be driven with a power supply of 12V. The disk device 200 can reproduce information on a CD-ROM disk at a speed of 42 times or more.

The disk apparatus 200 does not include the vibration level detecting means 9 (FIG. 1), and the focusing error signal FE and the tracking error signal TE output from the head control means 8 are the disk discriminating means 10. ) Is entered. The determination result of the disc discrimination means 10 is output to the brushless motor control means 33.

The brushless motor control means 33 controls the whole disk apparatus 200 by controlling the lead angle correction means 23 and the brushless motor driver 32, for example. The position detection signals HU, HV, HW from the rotor position detection means 20 are output to the lead angle correction means 23.

The lead angle correction means 23 includes phase lead circuits 23U, 23V, 23W. As shown in FIG. 3, each of the phase lead circuits 23U, 23V, and 23W includes a first time constant determining resistor 12, a second time constant determining resistor 13, a gain determining resistor 14, and a capacitor ( 15), FET 25, and operational amplifier 26. The differential circuit includes a first time constant determining resistor 12, a second time constant determining resistor 13, and a capacitor 15. Each of the phase read circuits 23U, 23V, 23W receives the position detection signals HU, HV, HW, and outputs the position detection signals KU, KV, KW. The position detection signals KU, KV, KW are obtained by correcting the lead angles of the position detection signals HU, HV, HW. In this embodiment, two time constant crystal resistors may be used (in FIG. 3, the first time constant crystal resistor 12, the second time constant crystal resistor 13). One of the two resistors (second time constant crystal resistor 13 in FIG. 3) is connected in parallel to the FET 25. The FET 25 has a gate and is configured to be a short circuit when sufficient bias is provided to turn on the FET 25 by a signal from the brushless motor control means 33. According to this structure, the time constant of each of the phase lead circuits 23U, 23V, 23W, that is, the relationship between the rotational speed and the lead angle can be switched between the two states. The circuit constant, i.e. the differential constant, can be changed by the FET 25 by shorting or turning off the second time constant determining resistor 13.

Referring to Fig. 3, the structure and function of the phase read circuits 23U, 23V, 23W will be described in more detail. 3 shows a circuit configuration of the phase lead circuits 23U, 23V, and 23W. Since the phase read circuits 23U, 23V, 23W are identical to each other, the disk device 200 includes three phase read circuits.

Without considering the FET 25, the phase read circuits 23U, 23V, 23W are the same as the general phase read circuit. The lead angle θ (degrees) is expressed by the following equation (5), where R (Ω) is the sum of the resistance of the first time constant determining resistor 12 and the resistance of the second time constant determining resistor 13. Where C (F) is the capacitance of the capacitor 15 and n (rpm) is the rotational speed of the brushless motor 5 (FIG. 1).

θ = tan ^-1 (R / Z)

Z = 1 / 2πfC

f = 0.1 n (5)

Here, f is the frequency (Hz) of each of the phase detection signals HU, HV, HW at the rotational speed n (rpm) of the brushless motor 5. Z is the impedance Ω of the capacitor 15 in this state.

As can be seen from equation (5), the phase lead angle θ simply increases as the rotational speed n increases. The phase lead angle θ increases as the value of R increases. The current delay caused by the coil inductance component of the brushless motor 5 increases with increasing rotation speed. The counter electromotive force of the brushless motor 5 increases in proportion to the rotational speed of the brushless motor 5. Therefore, the above-described characteristic that the phase lead angle θ simply increases as the rotational speed increases and as the R value increases (i) compensates for the current delay caused by the coil inductance and provides a weak field effect. There is an advantage in leading this further.

In accordance with the above-described characteristics, a sufficiently large phase lead angle for high speed rotation can be realized while avoiding the brushless motor 5 start-up failure, insufficient torque caused by unnecessary leads of phase during low speed rotation, and excessive vibration. have. In addition, the phase lead angle is automatically changed by the phase lead angle circuits 23U, 23V, 23W. Therefore, the load on the control means can be ignored. The phase lead angle circuits 23U, 23V, 23W can be realized with a very simple structure.

When sufficient bias is provided by the signal from the brushless motor control means 33, the FET 25 can bring the source-drain resistance value to almost zero. When no bias is provided, the source-drain resistance value is almost infinite. As shown in FIG. 3, the source and the drain of the FET 25 are connected in parallel to the second time constant crystal resistor 13. Therefore, the FET 25 can cause the second time constant determining resistor 13 to become a disconnect circuit when sufficient bias is provided by the signal from the brushless motor control means 33.

When the second time constant determining resistor 13 becomes a disconnecting circuit, the R value in Equation (5) is equal to the value of the first time constant determining resistor 12. When no bias is provided to the FET 25, the R value becomes equal to the sum of the value of the first time constant determining resistor 12 and the value of the second time constant determining resistor 13. Accordingly, the time constant of each of the phase lead circuits 23U, 23V, and 23W, that is, the relationship between the rotational speed and the lead angle, can be switched between the two states. As can be seen from FIG. 3, the function of changing the time constant of each of the phase read circuits 23U, 23V, 23W can be realized with a very simple structure.

When the optical disc 1 is a DVD-RAM disc, the rotation speed of the optical disc 1 is low at 3250 rpm, and the rotation speed for the search operation needs to be changed for ZCLV control. Therefore, the fast search operation requires a large torque. The brushless motor 5 is designed for this purpose to generate a torque large enough at the normal drive voltage. Thus, in this case the phase lead angle can be as small as the angle used to correct the current delay caused by the coil inductance component. By providing such a small lead angle to the brushless motor, the torque can be further improved.

In this embodiment, the lead angle is set at 7 degrees at 3250 rpm. In order to realize a lead angle of 7 degrees, it is necessary to set C = 0.01 ms and R = 6 ms in equation (5).

In order to realize the rotational speed of 9000 rpm necessary for 42x reproduction of information from a CD-ROM disc, it is necessary to further increase the phase lead angle so that a weak field effect is provided. In this embodiment, the lead angle is set at 50 ° at 9000 rpm. In order to realize a lead angle of 50 °, it is necessary to set C = 0.01 ms and R = 21 ms in equation (5).

As described above, each constant differs depending on whether the optical disc 1 is a DVD-RAM disc or a CD-ROM disc. If the constants are fixed for any kind of disc, the torque is insufficient or the maximum rotational speed is not obtained.

In this embodiment, the value of the first time constant determining resistor 12 is set to 6 Hz, which is necessary for the DVD-RAM, and the value of the second time constant determining resistor 13 is set to 15 Hz. The resistance value required to perform 42x reproduction of the information from the CD-ROM is 21 kΩ. The difference between 6 ms and 21 ms is determined as the value of the second time constant determining resistor 13.

According to this setting, when sufficient bias is provided to the FET 25, the lead angle is 7 degrees at 3250 rpm, which is suitable for a DVD-RAM disc. This is shown as characteristic 27 in FIG. When no bias is provided to the FET 25, the lead angle is 50 ° at 9000 rpm, which is suitable for 42x playback of a CD-ROM disc. This is shown as characteristic 28 in FIG.

The gain determining resistor 14 determines the overall amplification factor. The amplification rate depends on the speed of rotation. When a CD-ROM disk is used and the gain resistance is 10 kW, the amplification factor is 0.48 at 0 rpm and 0.74 at 9000 rpm. Such fluctuations do not significantly affect the characteristics of the brushless motor 5.

Phase lead circuits 23U, 23V, 23W invert the phases in this embodiment. The brushless motor 5 is designed to accommodate inversion.

Referring to Figs. 2 and 3, the operation of the disk device 100 of the above structure will be described. When the power of the disk apparatus 200 is turned on or when the optical disk 1 is loaded by a loading mechanism (not shown), the disk discriminating means 10 determines the disk type.

First, the operation of the disk device 200 when the disk is a CD-ROM will be described. When the disc discrimination means 10 detects that the disc is a CD-ROM disc, the brushless motor control means 33 sets the bias provided to the FET 25 of the read angle correction means to zero, thereby leading to a phase read. The time constants of the respective circuits 23U, 23V, and 23W are converted to values desirable for reproducing information from the CD-ROM disc.

When the brushless motor 5 is started to start the rotation of the optical disc 1, the lead angle is stable at 0 ° as indicated by characteristic 28 in FIG. As the number of revolutions increases, the phase leads gradually. Accordingly, the brushless motor 5 is driven at the optical weak electric field. This increases the rotation speed and continuously accelerates the brushless motor 5.

During this period, the brushless motor control means 33 only controls the drive voltage while monitoring the rotational speed. That is, the brushless motor 5 can be accelerated up to 9000 rpm by control exactly the same as the normal control.

When the disc is a DVD-ROM disc, the brushless motor 5 is driven by basically the same procedure as that for the CD-ROM disc except that the rotational speed is different.

Next, the operation of the disk device when the disk is a DVD-RAM disk will be described. Even in this case, the brushless motor 5 is driven by basically the same procedure as that of the CD-ROM disk except that the rotational speed is different. When the disc discrimination means 10 detects that the disc is a DVD-RAM disc, the brushless motor control means 33 provides a sufficient bias to the FET 25 of the lead angle correction means 23. This converts the time constants of the phase angle circuits 23U, 23V, 23W to values desirable for writing information to and reproducing the information on a DVD-RAM disc. As a result, as shown by characteristic 27 in FIG. 12, the relationship between the rotational speed and the phase lead angle is obtained.

When the brushless motor 5 is started to start the rotation of the optical disc 1, the lead angle is stable at 0 ° as shown by characteristic 27 in FIG. As the rotational speed increases, the phase leads gradually. Thus, the brushless motor 5 is driven with a corrected current delay caused by the coil inductance component. This increases the rotation speed of the brushless motor 5.

The brushless motor control means 33 drives the brushless motor 5 in ZCLV control. When the optical head 6 is on the innermost position of the DVD-RAM disc, the disc rotation speed is set to 3250 rpm. When the optical disc 6 is on the outermost position of the DVD-RAM disc, the disc rotation speed is set to 1350 rpm. The disk rotational speed can always vary within the range of 3250 rpm to 1350 rpm depending on the position of the optical head 6. As described above, the brushless motor 5 is designed to take some rotational speed range used for the brushless motor 5 to have optimum motor characteristics. In addition, the brushless motor 5 is driven with a corrected current delay caused by the coil inductance component. Therefore, the time required to change the rotational speed of the disk accompanied by the search operation can be shortened.

The rotation speed of the brushless motor 5 changes frequently, but the control is simple for the following reason. In order to correct the current delay caused by the inductance component, the lead angle is automatically changed by the function of the lead angle correction means 23 as described above. Therefore, it is not necessary for the brushless motor control means 33 in the disk apparatus 200 to change the setting of the lead angle.

As described above, in the second embodiment, the relationship between the size of the lead angle and the rotational speed can be switched by the lead angle correction means 23 in accordance with the output from the disc discrimination means 10. Since the brushless motor 5 can be driven by providing an optimum lead angle corresponding to the rotational speed of each type of disc, the highest possible performance of the brushless motor 5 can be achieved. Even when different rotation control systems such as a ZCLV rotation control system and a CAV rotation control system are used for different kinds of optical disks, the same control can be performed as in the conventional disk apparatus. Therefore, the load on the brushless motor control means 3 is insignificant. The overall structure of the disk device 200 is simple and easy to realize.

(Example 3)

4 is a schematic structural diagram of a disk device 300 in a third embodiment of the present invention. In this embodiment, the disc device 300 can record information on and reproduce information from a DVD-RAM disc, and can reproduce information from a CD-ROM disc at a speed of 42 times or more.

In this embodiment, the structure of the disk device 200 is basically the same as that of the disk device 200.

The disk device 300 has a lead angle correction means 24 different from the disk device 200. The lead angle correction means 23 includes a differential circuit in the disk device 9200, while the lead angle correction means 24 in the disk device 300 includes an integration circuit.

5 and 6, the structure and function of the lead angle correction means 24 will be described in detail. FIG. 5 shows the structure of each of the phase lead angle circuits 24U, 24V, and 24W included in the lead angle correction means 24. As shown in FIG. Since the phase lead circuits 24U, 24V, 24W are identical to each other, the disk device 300 includes three phase lead circuits.

Each of the phase lead angle circuits 24U, 24V, 24W includes an inverter 41, an amplifier 42, an adder 43, a FET 44, a first time constant determining resistor 45, a second time constant determining A resistor 46 and a capacitor 47. The inverter 41 inverts the position detection signals HU, HV, HW from the rotor position detection means 20 (Fig. 4) to lead the phases of the signals by 180 degrees. The amplification factor of the amplifier 42 is K.

The integration circuit includes a first time constant determining resistor 45, a second time constant determining resistor 46, and a capacitor 47. By shorting or turning off the second time constant determining resistor 46 using the FET 44, the circuit constant, i.e., the integral constant, can be changed.

Referring to Fig. 6, the operation of the phase lead angle circuits 24U, 24V, 24W will be described in more detail. FIG. 6 is a vector diagram showing the phase relationship between signals received and output by the read angle correction means 24. As shown in FIG. In FIG. 6, the position detection signal HU is one of the outputs from the rotor position detection means 20, and is the position detection signal HU shown in FIG. The position detection signals HV and HW of FIG. 6 are the same as the position detection signals HV and HW of FIG. 4, respectively. The signal HBU is an output signal from the inverter 41. The signal HRU is a signal component of the output signal applied across the capacitor 47. The signal HRU has the same phase as that of the signal HBU. The signal HIU is a signal component of the output signal applied to both ends of the capacitor 47. The signal HIU has a phase delayed by 90 ° with respect to the signal HBU. Signal HAU is an output signal from amplifier 42. The signal HDU is a signal component corresponding to the difference between the signal HAU and the signal HRU. The position detection signal KU is an output signal from the adder 43 and is a position detection signal KU output from the phase lead angle correction means 24 in FIG. 4. The position detection signals KV and KW of FIG. 6 are the position detection signals KV and KW shown in FIG. 4, respectively.

The phase and amplitude of the rotor position detection means 20 received and output by the lead angle correction means 24 are represented by the position detection signal HU, and the lead angle thereof is 0 degrees. The position detection signal HU is input to the inverter 41 and inverted. As a result, the phase of the position detection signal HU is read by 180 degrees. The resulting signal is represented as signal HBU. The signal HBU is input to an integrating circuit comprising a first time constant determining resistor 45, a second time constant determining resistor 46, and a capacitor 47.

The output from the integrating circuit applied across the capacitor 47 is the signal HRU having the same phase as the phase of the signal HBU, and the signal HIU having a phase delayed by 90 ° with respect to the phase of the signal HBU. It includes. The signal HIU is read by 90 ° with respect to the position detection signal HU output from the rotor position detection means 20. The position detection signal HU is input to the amplifier 42 to be a signal HAU and amplified by K.

The output from the integral time including the signal HRU and the signal HIU, and the signal HAU output from the amplifier 42 are input to the adder 43 and added together. By addition, the signal HRU and the signal HAU are neutralized with each other. Eventually, the signal HDU remains. The signal HIU is output as it is. Accordingly, the position detection signal KU including the signal HDU and the signal HIU as the components and having the read angle θ is output.

The time constant of the integrating circuit comprising the first time constant determining resistor 45, the second time constant determining resistor 46, and the capacitor 47 is less than the cycle of the position detection signal HU from the rotor position detector means 20. When set significantly smaller (1/900 Hz = 1.11 ms), the signal HRU has the same value as the value of the signal HBU without depending on the frequency. The signal HIU has an amplitude proportional to frequency. Therefore, by setting the amplification factor K of the amplifier 42 to a suitable value larger than 1, the signal HDU has a constant amplitude irrespective of the phase and frequency that are the same as the phase of the output from the rotor position detecting means 20. The signal HIU is read by 90 ° with respect to the signal HDU, and its amplitude increases in proportion to the frequency. Therefore, the read angle θ of the position detection signal KU having the signal HDU and the signal HIU as components increases with increasing frequency.

As in the second embodiment, in order to realize the rotational speed of 9000 rpm necessary for 42x reproduction of information from the CD-ROM disc, the circuit constants are set as follows. The sum of the resistance value of the first time constant determining resistor 45 and the resistance value of the second time constant determining resistor 46 is set to 1 Hz, the value of the capacitor 47 is set to 0.03 Hz, and K is 1.1. Set to. As a result, the same phase characteristics as in the second embodiment are obtained. In order to obtain the same characteristics as the second embodiment suitable for recording information on and reproducing the information from the DVD-RAM disc, the constants are set as follows. The sum of the resistance value of the first time constant determining resistor 45 and the resistance value of the second time constant determining resistor 46 is set to 200 Hz, and the other constants are used for 42 times speed reproduction of information from the CD-ROM disc. It is set to the same value as

Each of the phase lead angle circuits 24U, 24V, 24W has the actual configuration shown in FIG. The phase lead angle circuits 24U, 24V, and 24W shown in FIG. 7 include the operational amplifier 51, the FET 52, the first time constant determining resistor 53, the second time constant determining resistor 54, and the gain determination. Resistors 55, 56, 57, and capacitor 58. The functions of the inverter 41, amplifier 42, and adder 43 shown in FIG. 5 are provided by a subtractor including an operational amplifier 51 and the like.

According to the structure shown in Fig. 7, the same phase characteristic as that provided by the lead angle correction means 23 (Fig. 2) of the second embodiment can be provided by setting the constants as follows. The resistance value of the first time constant determining resistor 53 is set to 200 mW, the resistance value of the second time constant determining resistor 54 is set to 600 mW, and each of the gain determining resistors 55, 56, 57 is respectively. The resistance value of is set to 10 ㏀.

The operation of the disk device 300 having the above configuration will be described. When the power supply of the disk apparatus 200 is turned on or when the optical disk 1 is loaded by the loading mechanism, the disk discriminating means 10 determines the disk type.

First, the operation of the disk device 300 when the disk is a CD-ROM disk will be described. When the disc discrimination means 10 detects that the disc is a CD-ROM disc, the brushless motor control means 33 sets the bias provided to the FET of the lead angle correction means 24 to zero, thereby leading to a phase read. The time constants of the respective circuits 24U, 24V, and 24W are converted to values desirable for reproducing information from the CD-ROM disc.

When the brushless motor 5 is started to start the rotation of the optical disc 1, the lead angle is stable at 0 ° as indicated by characteristic 28 in FIG. As the rotational speed increases, the phase is progressively read. Accordingly, the brushless motor 5 is driven at the optical weak electric field. This increases the rotation speed and continuously accelerates the brushless motor 5.

During this period, the brushless motor control means 33 only controls the drive voltage while monitoring the rotational speed. That is, the brushless motor 5 can be accelerated up to 9000 rpm by control exactly the same as the normal control.

When the disc is a DVD-ROM disc, the brushless motor 5 is driven by basically the same procedure as that for the CD-ROM disc except that the rotational speed is different.

Next, the operation of the disk device when the disk is a DVD-RAM disk will be described. When the disc discrimination means 10 detects that the disc is a DVD-RAM disc, the brushless motor control means 33 provides a sufficient bias to the FET 44 or 52 of the lead angle correction means 23. This converts the time constants of the phase lead angle circuits 24U, 24V, 24W to values desirable for writing information to and reproducing the information on a DVD-RAM disc. As a result, as shown by characteristic 27 in FIG. 12, the relationship between the rotational speed and the phase lead angle is obtained.

When the brushless motor 5 is started to start the rotation of the optical disc 1, the lead angle is stable at 0 ° as indicated by characteristic 27 in FIG. As the rotational speed increases, the phase leads gradually. Accordingly, the brushless motor 5 is driven by correcting the current delay caused by the coil inductance component. This increases the rotation speed of the brushless motor 5.

The brushless motor control means 33 drives the brushless motor 5 in ZCLV control. When the optical head 6 is on the innermost position of the DVD-RAM disc, the disc rotation speed is set to 3250 rpm. When the optical disc 6 is on the outermost position of the DVD-RAM disc, the disc rotation speed is set to 1350 rpm. The disk rotational speed can always vary within the range of 3250 rpm to 1350 rpm depending on the position of the optical head 6. As described above, the brushless motor 5 is designed to take some rotational speed range used for the brushless motor 5 to have optimum motor characteristics. In addition, the brushless motor 5 is driven by correcting the current delay caused by the coil inductance component. Therefore, the time required to change the rotational speed of the disk accompanied by the search operation can be shortened.

The rotation speed of the brushless motor 5 changes frequently, but the control is simple for the following reason. In order to correct the current delay caused by the inductance component, the lead angle is automatically changed by the function of the lead angle correction means 23 as described above. Therefore, it is not necessary to change the setting of the lead angle by the brushless motor control means 300 in the disk apparatus 200.

In general, the outputs from Hall elements 21U, 21V, 21W contain large noise components since the waveforms are significantly distorted. These waveform distortions and noise components are included as frequency components higher than the frequency of the fundamental waves of the outputs. Thus, if a phase lead circuit is used to increase the gain as the frequency increases, the waveform distortion and noise components increase and act as disturbance factors. However, in this embodiment, the lead angle correction circuit 24 includes an integration circuit. Therefore, waveform distortions and noise components are reduced, so its influence can be ignored.

As described above, in the third embodiment, the relationship between the magnitude of the lead angle and the rotational speed can be switched by the lead angle correction means 24 in accordance with the output from the disc discrimination means 10. Since the brushless motor 5 can be driven by providing an optimum lead angle corresponding to the rotational speed of each type of disc, the highest possible performance of the brushless motor 5 can be achieved. Even when different rotation control systems such as a ZCLV rotation control system and a CAV rotation control system are used for different kinds of optical disks, the same control can be performed as in the conventional disk apparatus. Therefore, the load on the brushless motor control means 33 can be ignored. The overall structure of the disk device 200 is simple and easy to realize. Since the lead angle correction means 24 includes an integral circuit, the lead angle correction means 24 is caused by noise components or waveform distortions even if they are included in the outputs from the Hall elements 21U, 21V, 21W. It is not affected.

In this embodiment, the signal HBU is used as a signal provided with some lead angle. The signal HBU has a phase leaded by 180 ° as a result of inverting the position detection signal HU shown in FIG. As described above, the position detection signals HU, HV, HW shown in FIG. 4 have phases to be offset with respect to each other by 120 °. Therefore, the signal HBU can be replaced with another signal obtained as follows. The signal whose phase is read by 120 ° with respect to the signal whose phase is to be read is selected from the remaining two signals. For example, a signal whose phase is read by 120 ° with respect to the position detection signal HU is selected from the phase detection signals HV and HW. The selected signal may be used instead of the signal HBU. In this case, the lead angle is up to 30 °, but a brushless motor of a suitable kind can be sufficiently performed even at a lead angle of up to 30 °.

FIG. 8 shows a phase read circuit 24U 'using position detection signals HV or HW instead of signal HBU. The phase lead circuit 24U 'shown in FIG. 8 has a structure obtained by deleting the inverter 41 from the structure of the phase lead circuit 24U shown in FIG. In the phase lead circuit 24U ', the position detection signal HU is input to the amplifier 42, and the position detection has a phase deviated by a predetermined angle (for example, 120 °) with respect to the position detection signal HU. The signal HV or HW is input to the first time constant determining resistor 45. Also for the position detection signals HV and HW, phase lead circuits 24V 'and 24W' corresponding to the phase lead circuit 24U 'are provided, respectively.

Each of the phase lead circuits 23U, 23V, 23W, 24U, 24V, 24W, 24U 'shown in Figs. 3, 5, 7, 8 has two time constant crystal resistors. Each phase read circuit may include any number of time constant crystal resistor (s) according to various conditions. For example, when the time constant is changed in three stages, each phase read circuit includes three time constant determining resistors.

The circuit constant can be changed by combining the on and off states of the FETs respectively connected to the time constant determining resistors. It is not necessary to connect the time constant crystal resistors in series. The time constant crystal resistors may be connected in parallel. Instead of time constant determining resistors, variable resistors may be used. Instead of FETs, bipolar transistors may be used.

Each of the differential circuit and the integration circuit may include a plurality of capacitors. In this case, the transistor may be connected in parallel to at least one of the capacitors. The circuit constant may be changed by switching the capacitance of the capacitor by the same method used for time constant crystal resistors.

According to the control device for a brushless motor and a disk device using the same, unnecessary vibration is detected by the vibration detecting means, and the lead angle setting means sets the size of the lead angle in accordance with the detected unnecessary vibration. Thus, even if the vibrations between the brushless motors and the optical disks are different, the lead angle can be effectively set within an acceptable range and the unnecessary vibration can be reliably limited to below a prescribed level. Therefore, the reliability of the disk device can be improved.

Since the size of the lead angle is set in accordance with the output from the disc discriminating means, the brushless motor can be provided with an optimum lead angle for each of the different types of discs having different levels of durability against vibration, so that the highest Possible performance can be derived from the disk device. In addition, it is possible to determine not only the type of disk but also whether the disk is a disk of a ZCLV rotation control system or a disk of a CAV rotation control system. Therefore, the lead angle can be simply set using the features of each rotation control system.

The outputs from the rotor position detection means are synthesized by the combining means after the amplitudes are equalized and the harmonic components are removed by the normalizing means. Therefore, even if the outputs from the rotor position detecting means have variations in amplitudes or distortions in waveforms, these factors do not adversely affect the setting accuracy of the lead angle on each phase. Accordingly, highly precise correction of the lead angle can be performed.

According to the control apparatus for a brushless motor of this invention, and the apparatus using the same, the circuit constant of a differential circuit or an integral circuit is changed according to the output from a disc discrimination means, and the relationship between the rotational speed and the lead angle of a brushless motor There is provided a lead angle correction means for changing. The lead angle correction means provides a lead angle having a variable amount at the output from the rotor position detecting means to generate current timing of the drive current to the stator coils. The lead angle correction means drives the brushless motor while always providing the brushless motor with an optimum lead angle corresponding to the rotational speed of each type of disc. Thus, the highest possible performance of the brushless motor can be derived.

According to the control device for a brushless motor of the present invention, and a device using the same, even when different rotation control systems such as a ZCLV rotation control system and a CAV rotation control system are used for different kinds of optical disks, the same control as in a conventional disk apparatus Can be performed. Therefore, the load on the brushless motor control means 33 can be ignored.

The control device for a brushless motor of the present invention, and the device using the same, are very simple in structure and easy to realize.

The control device for a brushless motor of the present invention, and the lead angle correction means of the device using the same, are not easily affected by noise components or waveform distortions even if they are included in the output from the Hall element.

The control device for a brushless motor of the present invention is not limited to being applied to a disk device and can be applied to any device including a brushless motor in which motor characteristics can be preferably varied.

Claims (20)

A brushless motor comprising a rotor magnet and a stator coil; Rotor position detecting means for detecting a plurality of magnetic pole positions of the rotor magnet; Vibration detection means for detecting unnecessary vibration of the brushless motor when the brushless motor is rotating; Lead angle setting means for setting the size of the lead angle so that the first output of the vibration detecting means does not exceed a predetermined allowable value; According to the second output of the lead angle setting means, the lead angle is provided to the third output of the rotor position detecting means, so that the brushless motor is always provided with an optimal lead angle corresponding to the required number of rotations. A brushless motor control device including lead angle correction means for generating a current timing of a drive current to the stator coils. A disk device comprising the brushless motor control device according to claim 1, wherein the brushless motor rotates an information disk, A head for recording information on or reproducing information from the information disc; Head control means for following the head on a track of the information disc, And the vibration detecting means detects an unnecessary magnitude of vibration from a tracking control error between the head and the track. A disk apparatus in which a plurality of types of information disks having different recording formats are interchangeably mounted. A brushless motor comprising a rotor magnet and a stator coil, said brushless motor rotating at least one information disk mounted in said disk device among said plurality of types of information disks; Rotor position detecting means for detecting a plurality of magnetic pole positions of said rotor magnet; Discriminating means for determining a recording format of the at least one information disk; Lead angle setting means for setting a size of a lead angle in accordance with a first output of said discriminating means; The stator to provide the lead angle to a third output of the rotor position detection means in accordance with a second output of the lead angle setting means, to provide the brushless motor with an always optimal lead angle corresponding to the required number of revolutions. And a lead angle correction means for generating a current timing of a drive current to the coil. The method of claim 3, Vibration detection means for detecting unnecessary vibration of the brushless motor when the brushless motor is rotating, And the lead angle setting means sets the magnitude of the allowable value of the unnecessary vibration in accordance with the first output, and sets the magnitude of the lead angle so that the fourth output of the vibration detection means does not exceed the allowable value. The method of claim 3, Among the plurality of types of information discs, at least a first information disc and a second information disc having a lower recording density than the first information disc are replaceably mounted; And when the discriminating means detects the first information disk, the lead angle setting means sets the lead angle smaller than when the discriminating means detects the second information disk. The method of claim 3, And the at least one information disk is driven by ZCLV control, and the lead angle is set to substantially 0 degrees. The method of claim 3, And the at least one information disk is driven by CAV control. The method of claim 3, Among the plurality of types of information discs, at least recording and reproduction information discs that can be used for recording and reproduction, and a reproduction-only information disc that can be used only for reproduction, are interchangeably mounted. And when the discriminating means detects the recording and reproducing information disc, the lead angle setting means sets the lead angle smaller than when the discriminating means detects the reproducing information disc. A brushless motor comprising a rotor magnet and a stator coil; Rotor position detecting means for detecting a plurality of magnetic pole positions of said rotor magnet; Providing a lead angle with a variable amount at the output of the rotor position detecting means to produce a current timing of the drive current to the stator coil to provide the brushless motor with an always optimal lead angle corresponding to the required number of revolutions. Including a lead angle correction means, The rotor position detecting means generates a plurality of detection signals having different phases, The read angle correcting means includes standardizing means for converting the plurality of detection signals into a plurality of normal sinusoidal signals having a predetermined amplitude, and combining means for synthesizing the plurality of normal sinusoidal signals at a predetermined ratio to each other. Brushless motor control device. The method of claim 9, And said normalizing means comprises a low pass filter for passing a signal of a band to a rotation frequency of said brushless motor, among said plurality of detection signals. The method of claim 9, And said normalizing means comprises an AGC circuit. A disk device comprising the brushless motor control device according to claim 9, wherein the brushless motor rotates an information disk. A head for recording information on or reproducing information from the information disc; And head control means for following the head to a track of an information disc. A disk apparatus in which a plurality of types of information disks having different recording formats are interchangeably mounted. A brushless motor comprising a rotor magnet and a stator coil, said brushless motor rotating at least one information disk of said plurality of types of information disks; Rotor position detecting means for detecting a plurality of magnetic pole positions of said rotor magnet; Current timing of the drive current to the stator coil to provide a lead angle having a variable amount at the first output of the rotor position detection means to provide the brushless motor with an always optimal lead angle corresponding to the required number of revolutions Lead angle correction means for generating a; Discriminating means for discriminating a recording format of at least one information disk mounted on the disk apparatus, The lead angle correction means includes a plurality of differential circuits, And a circuit constant of each of the plurality of differential circuits is changed in accordance with the second output of the discriminating means, and the relationship between the rotational speed of the brushless motor and the lead angle is changed. The method of claim 13, Each of the plurality of differential circuits, A plurality of resistors; A capacitor; At least one transistor connected in parallel to at least one of said plurality of resistors, And the circuit constant is changed by switching on and off states of the at least one transistor. A disk apparatus equipped with replaceable plurality of types of information disks having different recording formats, A brushless motor comprising a rotor magnet and a stator coil, said brushless motor rotating at least one information disk of said plurality of types of information disks; Rotor position detecting means for detecting a plurality of magnetic pole positions of said rotor magnet; Current timing of the drive current to the stator coil to provide a lead angle having a variable amount at the first output of the rotor position detection means to provide the brushless motor with an always optimal lead angle corresponding to the required number of revolutions Lead angle correction means for generating a; Discriminating means for discriminating a recording format of the at least one information disk mounted in the disk apparatus, The lead angle correction means includes a plurality of integration circuits, And a circuit constant of each of the plurality of integrating circuits is changed in accordance with the second output of the discriminating means, and the relationship between the rotational speed of the brushless motor and the lead angle is changed. The method of claim 15, Each of the plurality of integration circuits, A plurality of resistors; A capacitor; At least one transistor connected in parallel to at least one of said plurality of resistors, And the circuit constant is changed by switching on and off states of the at least one transistor. The method of claim 16, The lead angle correction means further includes a plurality of inverters, And a third output obtained by inverting the first output by one of the plurality of inverters is input to at least one of the plurality of resistors. The method of claim 16, The lead angle correction means further comprises a plurality of amplifiers; The first output includes a first signal and a second signal having a predetermined angle with respect to each other, The first signal is input to a first amplifier of the plurality of amplifiers, And the second signal is input to at least one of the plurality of resistors of the first integration circuit corresponding to the first amplifier, among the plurality of integration circuits. The method of claim 15, And a predetermined lead angle is provided in advance in said first output. The method of claim 15, The stator coil comprises N phases driven by a drive current having a predetermined angle with respect to each other, The first output includes N signals having the predetermined angle with respect to each other, The read angle correction means generates current timing of a drive current to the stator coil using n signals among the N signals, Wherein N is an integer of 2 or more and n is an integer of 2 or more or N or less.