JP2001298986A - Motor controller, disc drive and acceleration detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of a system for predicting heat generation of a motor from a current command value to the motor that prediction accuracy is low because the current command value is not proportional to the current actually flowing through the motor. SOLUTION: The motor controller comprises means for detecting acceleration of a motor, means for supplying a drive current to the motor, means for calculating heat generation of the motor based on the output at least from the acceleration detecting means, and means for controlling the motor drive means, based on the heat generation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention calculates a heat value of a motor, predicts a temperature rise of the motor or a device on which the motor is mounted from the heat value, and controls the operation of the motor based on the prediction result. The present invention relates to a motor control device for preventing a rise in temperature and a disk device on which the motor control device is mounted.

[0002]

2. Description of the Related Art A motor is a device that has been incorporated and used in various types of devices. The motor generates a torque (ie, torque) corresponding to the magnitude of the current by applying a current to a motor coil, thereby controlling a drive target. It is to rotate. When the motor rotates at a constant speed, only a torque corresponding to a bearing load or the like needs to be generated, so that a small amount of current is applied. However, when a drive that rapidly accelerates or decelerates the rotation speed is required, a torque corresponding to the magnitude of the acceleration is required, and a current having a magnitude corresponding to the required torque needs to be supplied. . At this time,
Heat generation of the motor coil caused by applying a current to the motor coil increases substantially in proportion to the square of the current. For this reason, in a device in which a motor that performs a drive that rapidly changes the rotation speed is incorporated, the heat of the motor coil is large due to the application of a large current, and it is a major problem to prevent the temperature rise due to this heat generation. Has become.

For example, in a disk device for recording / reproducing information by moving a recording head while rotating a recording medium disk, an operation of moving the recording head to a desired position at a high speed is called a seek. Seeks may be repeated frequently. During this seek, it is necessary to rapidly change the rotation speed of the head transfer motor for transferring the head and the disk motor for rotating the disk.
There is a problem that the temperature of the disk or the device exceeds the heat-resistant temperature of the disk or the device due to the temperature rise accompanying the heat generated during the seek, and the temperature rise has been solved.

For example, Japanese Patent Application Laid-Open No. 6-119008 discloses a method in which a temperature sensor is provided inside an optical disk device to detect the temperature, and the operation of the optical disk device is restricted when the temperature of the optical disk device exceeds a preset temperature. This discloses a configuration for preventing an excessive rise in temperature.

[0005] Further, in order to reduce the cost of parts and the number of assembling steps involved in mounting the temperature sensor, or to know the temperature of a place where it is difficult to directly mount the temperature sensor, temperature prediction of a desired place is calculated. Techniques for doing so have also been proposed. For example, Japanese Patent Laid-Open No. 7-153208 discloses a voice coil motor (VC
A configuration is disclosed in which the temperature rise of the VCM is predicted by calculation from the current instruction value to M).

FIG. 10 shows a conventional magnetic disk drive 101 for predicting temperature rise by calculation. The magnetic disk device 101 includes a servo controller 118 and a disk enclosure (hereinafter, referred to as “DE”) 102. The servo controller 118 controls the VCM controller 13
5, the VCM control unit 135 includes a RAM 122, a positioning control unit 115, and a temperature detection unit 114 that predicts the temperature of the VCM. The DE 102 includes a disk motor 103, a spindle 104, and a magnetic disk 105
And a voice coil motor (hereinafter referred to as “VCM”) 10
6 and a magnetic head 107. The magnetic head 107 is moved in the radial direction of the magnetic disk 105 by the VCM 106, and the magnetic head 107 is positioned.

The RAM 122 stores data such as iv (VCM current instruction value), ΔQv1 (heat amount for temperature rise), ΔQv2 (heat amount for natural heat radiation), Qv (heat amount for measurement target), and Tv (temperature for measurement target). Is stored in an updatable manner. Further, a timer (soft timer) is set in the RAM 122. The ROM (not shown) has K (constant), θ
(Constant by thermal resistance), Cv (heat capacity of measurement object), T
e (ambient ambient temperature), ts (sampling time), a
Data such as (constant) and b (constant) are stored in advance.

The magnetic disk drive 10 configured as described above
1, the temperature detection unit 114 performs the following procedure on the VCM1
The prediction calculation of the temperature of 06 is performed.

The VCM controller 135 interrupts the normal seek control every 66 μsec sampling time ts, detects the position of the magnetic head 107,
The current instruction value iv is updated.

Next, the temperature detector 114 multiplies the square of the VCM current instruction value iv by the coefficients K and ts, and subtracts the heat quantity ΔQv2 of the heat radiation of the measurement object from the heat quantity ΔQv1 of the temperature rise of the measurement object. Integrate the value (Qv ← Qv + Δ
Qv1−ΔQv2) to obtain the heat quantity Qv of the control target, thereby detecting the temperature Tv of the measurement target (Tv = Qv).
/ Cv).

The above processing is performed for each sampling time ts, and the temperature Ts is detected and stored in the RAM 122. Then, when performing a seek, the temperature Tv is read from the RAM 122, and seek control is performed based on the temperature Tv.

In this seek control, the detected temperature T
When v is larger than the reference value, the start of the seek is delayed according to the temperature Tv, thereby suppressing the temperature rise.

The delay amount D 'for delaying the start of the seek is set as D' = a.Tv-b as a linear function of the temperature Tv (where a and b are constants stored in the ROM).

In this case, the delay amount D 'is set as follows according to the temperature Tv. That is, the reference value for the temperature Tv is T1 ′, and D ′ is T ′ in the region of Tv ≦ T1 ′.
= 0, and in the region of Tv> T1 ′, D ′ = a ·
Tv-b is set.

Therefore, if the temperature Tv is equal to or lower than the reference value T1 ', the seek operation is started immediately upon receiving a seek command, and if the temperature Tv exceeds the reference value T1', the seek is delayed by a delay amount proportional to the temperature Tv. To start seeking. Thereby, the temperature rise of the VCM 106 is suppressed, and the VC
Overheating of M106 is prevented.

[0016]

However, in the above-described conventional magnetic disk drive 101, the heat value .DELTA.Q
There is a problem that the calculation accuracy of v1 may be significantly deteriorated.

The heat value ΔQv1 of the VCM 106 is
It can be calculated by multiplying the square of the current flowing through the coil 106 by a constant (coil resistance and energizing time).
In the conventional example, the calculation is performed using the current instruction value instead of the current value itself, and it is assumed that a proportional relationship is established between the current value and the current instruction value iv. However, the current instruction value iv and the current value actually flowing through the VCM 106 are not always in a proportional relationship.

FIG. 11 shows a general motor driver IC.
The relationship between the current instruction value iv and the current value i actually flowing is shown.
As shown by the one-dot chain line in FIG. 11, in the conventional method, a proportional relationship (i = c · i) is established between the current instruction value iv and the current value i.
v) is assumed. However, there is actually a current instruction value range called a dead zone, and in this range, the output current value i becomes 0 regardless of the magnitude of the current instruction value iv. Further, the size of the range of the dead zone greatly varies depending on the IC, and a proportional relationship is not established between the current instruction value iv and the current value i. Further, the relationship between the current instruction value iv and the current value i (i = c1 ・ iv + d1) is (i = c2 ・ iv + d) in a region where the current instruction value iv is larger than a certain constant iv0.
2), and has a nonlinearity that the proportional constants (c1 and c2) change depending on the range of the current instruction value iv. Furthermore, the constants c1, c2, d1, and d2 greatly vary depending on the IC, and the output current i differs greatly depending on the IC even for the same current instruction value iv.

The driver IC detects the current value i that is actually flowing and controls its feedback by monitoring the voltage across the detection resistor inserted in series with the motor. However, the resistance value of this detection resistor is as small as about 0.1Ω in order to reduce the motor drive loss, and it is difficult to improve the accuracy of current detection because the effects of wiring resistance errors inside the IC cannot be ignored. .

For the above reason, for example, the current value i calculated by the method of the prior art for a certain current instruction value iv1
There is a large error between calc and the current value ireal actually flowing, and the calorific value ΔQv1 calculated from the current icalc is also significantly different from the amount of heat actually generated by the VCM 106, and the accuracy of temperature prediction is extremely poor. turn into.

Further, based on the inaccurate temperature estimation result, V
Since the CM 106 is controlled, the actual temperature becomes equal to the reference value T1 '.
, The VCM 106 is overheated or destroyed without performing an operation for delaying the start of the seek, or the start of the seek is delayed even though the actual temperature is sufficiently lower than the reference value T1 '. There is a problem that the performance of the magnetic disk device 101 is reduced.

Further, when the current value i actually flowing is to be directly detected with high accuracy, the equipment for this purpose is complicated, and there is a drawback that the cost of parts and the number of assembly steps increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has a more accurate heat generation amount calculation function, and controls the motor operation at an appropriate timing to prevent troubles caused by overheating. It is an object of the present invention to provide a motor control device, a disk device, and an acceleration detection device that can achieve both prevention of the occurrence of the vibration and securing of the performance of the device.

[0024]

According to the present invention, there is provided a motor control device comprising: an acceleration detecting means for detecting an acceleration of a motor; a motor driving means for supplying a driving current to the motor; and at least an output of the acceleration detecting means. And a motor control means for controlling the motor drive means based on the heat generation amount.

The acceleration detecting means includes a displacement measuring means for measuring a predetermined displacement of the motor, and a time measuring means for measuring a time required for the predetermined displacement. The acceleration may be calculated based on the output and the output of the timing unit.

The calorific value calculating means may hold a relationship between the acceleration and the calorific value, and calculate the calorific value from at least the acceleration output from the acceleration detecting means based on the relationship.

The heat generation amount calculation means may calculate the heat generation amount of the motor based at least on a first value obtained by multiplying the square of the acceleration by a first constant.

[0028] The apparatus may further comprise inertia determination means for determining inertia of a load when the motor is driven, and the first constant may be changed by an output of the inertia determination means.

The acceleration detecting means calculates a predetermined rotational displacement by multiplying the predetermined displacement by a predetermined integer, and the heat generation amount calculating means calculates a first constant obtained by multiplying a square of the acceleration by a first constant. And a heat value of the motor may be calculated based on at least a sum of a value obtained by multiplying the predetermined rotational displacement by a second constant.

[0030] An inertia discriminating means for discriminating a load inertia when the motor is driven may be further provided, and the first constant may be changed by an output of the inertia discriminating means.

The acceleration detecting means measures a predetermined displacement of the motor and generates a pulse at each of the predetermined displacements; a time measuring means for measuring a pulse generation interval; Speed calculation means for calculating the speed of the motor from the pulse generation interval every time a predetermined rotational displacement of an integral multiple of the predetermined displacement is performed, wherein the acceleration detection means calculates the acceleration from the speed May be.

[0032] The predetermined rotational displacement may be equal to an integral multiple of the rotational displacement per rotation of the motor.

The acceleration detecting means includes a displacement measuring means for generating a pulse each time the motor is displaced by a predetermined angle D, and a rotational speed N of the motor each time the displacement measuring means generates the n-th pulse. A velocity calculating means for calculating (n) by the following (Equation 1), and an i-th calculated acceleration A (i) by the following (Equation 2) every time j pulses are generated. And a difference calculating means.

N (n) = D / Δtp (n) (Equation 1) A (i) = (N (j · i) −N (j · (i−1))) / Δt (i) (Equation 2) where n, i and j are positive integers and Δtp
(N) is the elapsed time between the nth pulse and the (n-1) th pulse generated by the displacement measuring means, and Δt (i)
Is the j / i-th pulse generated by the displacement measuring means and j
The elapsed time from the (i-1) th pulse.

The value of j may be an integral multiple of the number of pulses generated by the displacement measuring means during one rotation of the motor.

The acceleration detecting means includes a digital filter to which the speed N (n) at which the motor is displaced is input and outputs an average speed N '(n).
The acceleration A (i) may be calculated using the average speed N ′ (n) instead of the speed N (n) in the above (Equation 2).

The digital filter may calculate the average speed N '(n) according to the following (Equation 3).

N ′ (n) = (N (n) + (m−1) · N ′ (n−1)) / m (Formula 3) Here, m is a positive integer.

The motor control means includes: a temperature calculating means for calculating at least one of a temperature change of the motor and a temperature change of an object to be driven by the motor based on the heat value calculated by the heat value calculation means; Current limiting means for limiting the drive current output from the drive means, wherein when the temperature change exceeds a predetermined threshold, the motor control means may set a limit value for the drive current.

The limit value may be changed according to the amount by which the temperature change exceeds the predetermined threshold.

According to the present invention, there is provided a disk apparatus comprising: a motor for rotating a disk; an optical head for recording information on the disk or reproducing information from the disk; and motor driving means for supplying a drive current to the motor. A motor control unit for setting the drive current; a speed calculation unit for calculating a rotation speed of the motor; and a rotation speed of the motor, which enables the optical head to record on or reproduce from the disk. Determining means for determining whether or not the rotation speed is within the rotation speed range, wherein the rotation speed of the motor is within the rotation speed range at which recording on the disk or reproduction from the disk by the optical head is possible. If the determination means determines that the above-mentioned condition exists, the motor control means limits the drive current.

[0042] The motor control means may set the limit value of the drive current higher as the target rotation speed of the motor is higher.

[0043] The motor control means may set the limit value of the drive current to be higher than that at the start of acceleration of the motor before the rotation speed of the motor is settled at the target rotation speed.

An acceleration detecting means for detecting the acceleration of the motor; a calorific value calculating means for calculating a calorific value of the motor based on at least the acceleration output from the acceleration detecting means; A temperature calculating means for calculating a temperature change in a predetermined area of the disk device, wherein the determining means further determines whether the temperature change is equal to or less than a predetermined threshold value, and If the determination unit determines that the rotation speed of the motor is within the rotation speed range at which recording or reproduction by the optical head is possible, the motor control unit determines the drive current. And the motor control means may limit the drive current if the determination means determines that the temperature change is not less than the predetermined threshold value.

[0045] The motor control means may set the limit value of the drive current higher as the target rotation speed of the motor is higher.

[0046] The motor control means may set the limit value of the drive current to be higher than when the acceleration of the motor is started before the rotation speed of the motor is settled at the target rotation speed.

The disk device of the present invention comprises: a motor for rotating a disk; an optical head for recording information on the disk or reproducing information from the disk; and a motor driving means for supplying a drive current to the motor. A motor control unit for setting the drive current; a synchronous clock generation unit for generating a synchronous clock based on a reproduction signal read from the disk by the optical head; a speed calculation unit for calculating a rotation speed of the motor; Determining means for determining whether or not the rotation speed of the motor is within a rotation speed range in which the synchronous clock generation means can generate the synchronous clock; When the determination unit determines that the rotation speed is within the rotation speed range that enables the generation of the synchronization clock by the unit, Serial motor control means for limiting the drive current.

[0048] The motor control means may set the limit value of the drive current higher as the target rotation speed of the motor is higher.

[0049] The motor control means may set the limit value of the drive current to be higher than that at the start of acceleration of the motor before the rotation speed of the motor is settled at the target rotation speed.

A disk device according to the present invention comprises a motor for rotating a disk, an optical head for recording information on the disk or reproducing information from the disk, and a motor driving means for supplying a drive current to the motor. A motor control means for controlling the motor; a speed calculation means for calculating a rotation speed of the motor; and whether or not the optical head is performing recording on the disk and reproducing from the disk, and rotation of the motor. Determining means for determining whether or not the speed has changed, wherein the optical head is not recording on or reproducing from the disk, and the rotational speed of the motor has changed. When the determination means determines, the motor control means:
The driving current is controlled so that the rotation speed of the motor is constant.

A disk device according to the present invention comprises: a motor for rotating a disk; an optical head for recording information on the disk or reproducing information from the disk; and a motor driving means for supplying a drive current to the motor. Motor control means for controlling the motor, head moving means for moving the optical head to a predetermined position on the disk where recording or reproduction is performed by the optical head, and speed calculating means for calculating a rotation speed of the motor And determining, during a seek operation in which the optical head moves, whether or not the rotation speed of the motor is within a rotation speed range at which recording or reproduction from the disk by the optical head is possible. And a rotation speed of the motor during the seek operation in which the optical head moves. When the determination unit determines that the rotation speed is within the rotation speed range that enables recording on the disk or reproduction from the disk, the motor control unit determines that the rotation speed of the motor is constant for a predetermined time. The drive current is controlled so as to be as follows.

A disk device according to the present invention comprises: a motor for rotating a disk; an optical head for recording information on the disk or reproducing information from the disk; and motor driving means for supplying a drive current to the motor. A motor control unit that sets the drive current; an acceleration detection unit that detects the acceleration of the motor; and a heat generation amount calculation unit that calculates a heat generation amount of the motor based on at least the acceleration output by the acceleration detection unit. A temperature calculating means for calculating a temperature change in a predetermined area of the disk device based on the heat generation amount, wherein the temperature change is equal to or greater than a predetermined threshold value. Determining means for determining whether or not the temperature change is equal to or more than the predetermined threshold value. The motor control means limits the drive current.

The speed detecting device according to the present invention comprises: a displacement measuring means for generating a pulse each time the motor makes a predetermined displacement; a time measuring means for measuring the pulse generation interval; Each time the predetermined rotational displacement is doubled,
Speed calculating means for calculating the speed of the motor based on the pulse generation interval, wherein the predetermined rotational displacement is equal to an integral multiple of the rotational displacement per rotation of the motor.

An acceleration detection device according to the present invention may include the speed detection device described above, and the acceleration may be calculated from the speed.

[0055]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 is a schematic configuration diagram of an optical disk device 1 according to a first embodiment of the present invention. The optical disk device 1 includes a motor control device 27, a turntable 3 on which the optical disk 2 is mounted, a disk motor 4 for driving the optical disk 2 and the turntable 3 to rotate, an optical head 5, and an optical head 5
A guide shaft 6 movably supporting in the radial direction of
A head transfer motor 7 for supplying a driving force for moving the optical head 5 supported by the guide shaft 6 to a desired radial position on the optical disk 2; a chassis 9; a head signal processing circuit 22; , Signal processing means 24.

The disk motor 4 includes a stator section 30 having a motor coil 29 that is energized to generate an electromagnetic field,
This is a DC motor having a ring-shaped rotor section 32 having a magnet 31 in which positive and negative magnetic poles are alternately magnetized in a circumferential direction. The disk motor 4 is provided with a sensor unit 10a of a displacement measuring unit 10 described later, and detects a rotational displacement of the disk motor 4.

The optical head 5 records information by irradiating the optical disk 2 with a laser beam, and irradiates the optical disk 2 with a laser beam and reflects the information recorded on the disk 2 by a reflected beam. Perform reading.

The chassis 9 is a resin base to which the disk motor 4, the guide shaft 6, the head transfer motor 7 and the like are fixed.

The motor control device 27 includes the acceleration detecting means 1
5, a calorific value calculating means 16, a motor driving means 17,
A motor control unit 21 and a CPU 25 having an inertia determination unit 26 are provided.

The acceleration detecting means 15 comprises:
The apparatus includes a velocity calculating unit 12, a digital filter 13, a difference calculating unit 14, and a waveform shaping unit 10b of the displacement measuring unit 10 described later.

The motor control means 21 includes a current instruction value generating means 18, a current limiting means 19, and a temperature calculating means 20.

The optical disk 2 is inserted into the optical disk device 1 by a loading mechanism (not shown), and the optical disk device 1 determines the type of the optical disk 2 and records or reproduces information on the optical disk 2. The optical disk 2 includes a CD-ROM and a DVD (Digita
1 Versatile Disk-ROM or a read-only optical disc, or a recordable / reproducible optical disc such as PD or DVD-RAM.

The displacement measuring means 10 is an encoder that outputs a pulse (rectangular wave) each time the disk motor 4 rotates by a unit angle (hereinafter, referred to as D), and includes a sensor section 10a including a Hall element and the like, and a sensor section 10a. And a waveform shaping unit 10b for shaping the output signal waveform of 10a. Sensor unit 10a provided in displacement measuring means 10 of motor control circuit 27
Is usually provided integrally with the disk motor 4, but may be provided separately. The sensor unit 10a provided integrally with the disk motor 4 is disposed at a position facing the magnet 31 provided on the rotor unit 32 of the disk motor 4, and has a positive / negative magnetic field that changes with the rotation of the rotor unit 32. The strength is detected and output as a sine wave signal. The waveform shaping unit 10b is provided in the acceleration detection unit 15, and shapes the sine wave output from the sensor unit 10a into a rectangular wave and outputs the rectangular wave. The rotational displacement (rotation angle) of the disk motor 4 can be calculated by counting the pulses output from the displacement measuring means 10. For example, if the encoder outputs 6 pulses in one rotation, the unit angle D displaced per pulse is 60 °
Therefore, the rotation displacement (rotation angle) can be measured by multiplying the counted pulse number by 60 °.

The clocking means 11 has a function of measuring time using the operation clock of the CPU 25.
The number of clocks between the pulses is counted by using the pulse output from b as a trigger, and the elapsed time is measured.
2. Output to the difference calculation means 14 and the heat generation amount calculation means 16 at necessary timing.

Each time the displacement measuring means 10 generates a pulse, the speed calculating means 12 obtains the elapsed time Δtp from the immediately preceding pulse generation from the time measuring means 11 and calculates the speed N (n) as shown below (Equation 1). ) (Where n is a positive integer). Here, the speed N (n) indicates that the speed was calculated when the n-th pulse was generated, and N (n-1) indicates that the speed was calculated when the immediately preceding pulse was generated. . D is a unit angle displaced per pulse as described above. In the following description, notations such as n and l attached to symbols indicating output and the like indicate the n-th and l-th measured values and calculated values, respectively.

N (n) = D / Δtp (n) (Expression 1) The digital filter 13 calculates the average speed N ′ (n) from the speed N (n) based on the following (Expression 3). calculate.

N ′ (n) = (N (n) + (m−1) · N ′ (n−1)) / m (3) where m is the cutoff frequency of the digital filter 13. Is a constant. Normally, when the disk motor 4 is rotating at a constant speed, the elapsed time between pulses should always be the same, and the elapsed time Δtp used by the speed calculation means 12 for calculating the speed N (n) is the same value. Should be. However, in practice, the same value is not obtained even when the motor 31 is rotating at a constant speed due to a variation in the magnetizing interval of the magnet 31 provided in the disk motor 4, and an error occurs in the calculation result of the speed N (n). May be mixed as high frequency noise. However, this error can be reduced by the operation of the digital filter 13, and the accuracy of prediction of the finally calculated temperature change can be improved.

The difference calculation means 14 is a digital filter 1
The acceleration A (i) is calculated based on (Equation 4) from the average speed N ′ (i) output by the output unit 3.

A (i) = (N ′ (j · i) −N ′ (j · (i−1))) / Δt (i) (Equation 4) where i is the i-th acceleration calculation A positive integer indicating that the calculation is performed, j is a predetermined integer. Here, j indicates how many pulses of the acceleration A (i) are calculated. Δt (i) is the elapsed time between the j · i-th pulse generated by the displacement measuring means 10 and the j · (i−1) -th pulse. j · i-th pulse and j · (i−
1) From the first pulse, the average speeds N ′ (j · i) and N ′
(J · (i−1)) is calculated. Acceleration calculation means 1
5 outputs the calculated motor acceleration A (i) to the calorific value calculation means 16.

The calorific value calculation means 16 includes the disk motor 4
Is calculated according to the following (Equation 5).

E (i) = α · A (i) ² · Δt (i) + Tm · j · D + E (i−1) (Equation 5) Here, α (first of equation 5) Constant) is a number calculated by (Equation 6).

Α = R · J ² / Kt ² (Equation 6) where R is the motor coil resistance, J is the inertia of the rotor 32 of the optical disk 2 and the disk motor 4, and Kt
Is the torque constant of the disk motor 4, Tm (second constant)
Is the bearing load torque of the disk motor 4. Tm is
In addition to the frictional resistance of the bearing portion, it may be set based on various resistance factors such as air resistance. J is the calorific value E
The number of pulses generated by the displacement measuring means 10 from the time of calculating (i-1) to the time of calculating E (i),
j · D corresponds to the rotational displacement of the motor.

Here, the first term of (Equation 5) is E1 (i),
Assuming that the second term is E2 (i), E1 (i) obtained by multiplying the square of the acceleration by the first constant can be rewritten as (Equation 7).

E1 (i) = R ・ (J ・ A (i) / Kt) ²・ Δt (i) (Equation 7) J ・ A (i) shown in (Equation 7) is calculated by Since the value is obtained by multiplying the acceleration, the motor torque is indicated by the equation of motion. The motor torque and the motor drive current have a substantially proportional relationship (the proportional constant is the torque constant K
Since t) holds, J · A (i) / Kt indicates the magnitude of the motor drive current. Therefore, the calorific value E1
(I) is calculated by multiplying the square of the motor drive current by the motor coil resistance and the elapsed time Δt (i).

The second term, E2 (i), is calculated by multiplying the bearing load torque Tm by the rotational displacement j · D to obtain the frictional heat generated by the bearing friction of the disk motor 4. The third term of (Equation 5) is calculated by calculating the calorific value E (i) by the calorific value calculator 16 as i−1
The calorific value E (i-1) calculated at the time is shown.

The calorific value E (i) by the calorific value calculating means 16
Is calculated by integrating the calorific value E (i-1) calculated at the (i-1) th time with the calorific value E1 (i) of the newly generated motor coil 29 and the frictional calorific value E2 (i). You.

Since a proportional relationship is established almost exactly between the torque of the DC motor and the drive current,
, The calorific value of the motor coil 29 can be calculated with high accuracy. However, strictly speaking, even for a motor in which a proportional relationship is not established, as long as it is possible to formulate between the calorific value of the motor and acceleration. , The calorific value can be calculated. For example, even if the relationship between the motor torque and the drive current is non-linear, the motor torque is calculated from the acceleration by the equation of motion, the drive current is calculated from the motor torque, and the motor is calculated by the following (Equation 8). The calorific value of the coil 29 can be obtained.

E1 (i) = R · I (i) ² · Δt (i) (Equation 8) Here, I (i) is a drive current of the motor.

The motor driving means 17 is a motor driver for supplying a current to the disk motor 4 in accordance with the current instruction value input from the current instruction value generating means 18.

The current instruction value generating means 18 receives from the CPU 25 a target position indicating where the recording / reproduction is to be performed on the optical disk 2, and determines the rotation speed of the disk motor 4 required for recording / reproduction at the target position. calculate. further,
The rotation speed of the disk motor 4 at that time is compared with the target rotation speed, and if they do not match, an acceleration or deceleration command necessary for matching the rotation speed and the magnitude of acceleration / deceleration are determined. The motor drive means 1 generates a current instruction value indicating whether a drive current is supplied to the disk motor 4.
7 is output.

The current limiting means 19 changes the current instruction value generated by the current instruction value generating means 18 and
7 limits the magnitude of the drive current supplied to the disk motor 4. The current limiting unit 19 receives, from the CPU 25, a limit command flag indicating whether to limit the drive current. In the case of limiting, the current limiting means 19 receives data indicating the limiting range, and operates according to the instruction. By limiting the drive current, it is possible to suppress heat generation of the disk motor 4 and suppress a temperature rise.

The temperature calculating means 20 calculates the k-th predicted temperature change value T (k) of the control object (the disc motor 4 or any component of the optical disc apparatus 1) whose temperature is to be controlled.
Is calculated as a k−1 th temperature change predicted value T (k−1) and k−
Elapsed time Δts from first calculation of temperature change predicted value
(K) and the calorific value E (i) are calculated according to (Equation 9).

T (k) = exp ｛−Δts (k) / τ｝ · T (k−1) + Kc · E (i) (Equation 9) where k, τ, and Kc are positive constants It is. The predicted temperature change value T (k) indicates not the temperature of the controlled object itself but the temperature difference between the controlled object and the surroundings of the controlled object.
Strictly speaking, it is assumed that the surrounding heat capacity is sufficiently large and the surrounding temperature change is slower than the temperature change of the control target. Further, τ and Kc are constants representing the time constant and the heat capacity of the controlled object, respectively. The first term on the right side of (Equation 9) indicates the temperature drop due to natural heat dissipation, and the second term indicates the calorific value E (i). Shows the temperature rise due to The values of τ and Kc are obtained in advance by experiments and stored in a ROM (not shown) provided in the motor control device 27. The control target may include, for example, a drive target of the disk motor 4 such as the disk motor 4 and the optical disk 2.

The motor control means 21 controls the motor drive means 17 based on a command from the CPU 25.

The head signal processing circuit 22 converts the signal read from the optical disk 2 by the optical head 5 into a binary signal, and outputs the signal to the synchronous clock generating means 23 and the signal processing means 24.
Output to

The synchronous clock generating means 23 has a PLL circuit (not shown) and generates a clock signal synchronized with the binary signal output from the head signal processing circuit 22. CLV (Constant Linear) for controlling the linear velocity of the optical disc 2 at the recording / reproducing position to be almost constant.
In a (Velocity) type optical disk, the rotational speed of the disk motor 4 capable of generating a synchronous clock differs depending on the radial position at which recording / reproduction is performed, and a predetermined rotational speed around a rotational speed predetermined for each radial position. Synchronous clock generation is possible only in the range of the width. Since the recording / reproducing operation can be performed only after the synchronizing clock can be generated, in the seek operation for changing the recording / reproducing position, the rotational speed of the optical disk 2 is set as much as possible within the rotational speed range where the synchronous clock can be generated. It is necessary to insert it promptly.

The signal processing means 24 performs demodulation and error correction on the basis of the clock signal generated from the synchronous clock generation means 23 and the binary signal output from the head signal processing circuit 22, and converts the data signal. The information generated and recorded on the optical disk is reproduced. Further, an information signal to be recorded is output to the optical head 5 based on the clock signal, and the information is recorded on the optical disk 2.

The CPU 25 controls the entire optical disc apparatus 1 based on programs and data stored in a ROM (not shown) in advance. For example, it exchanges commands and data with the host device 28 via a SCSI interface (not shown), or performs various controls in the optical disc device 1 including the control of the motor control means 21. For example, the CPU 25
Immediately before the seek operation is started based on the information reproducing or recording command from the CPU, a predicted temperature change value of a predetermined portion (for example, the inner and outer circumferences of the disk) is obtained from the temperature calculating means 20, and the temperature change predicted value A command is sent to the current instruction value generating means 18 and the current limiting means 19 on the basis of the control signal to control the drive current of the disk motor 4.

The inertia determination means 26 is executed by the CPU 25 as a program stored in a ROM (not shown). The inertia discriminating means 26 discriminates the difference in the diameter of the optical disc 2 based on the content of the data signal output from the signal processing means 24 to calculate the inertia, and calculates the heat generation amount calculating means 16 as a constant α (first constant).
Output to

The acceleration detecting means 15 and the calorific value calculating means 1
6. The motor drive unit 17, the motor control unit 21, the head signal processing circuit 22, the synchronous clock generation unit 23, the signal processing unit 24, and the CPU 25 can be provided on a circuit board.

The motor control device 27 configured as described above
The operation of the optical disk device equipped with the motor control device 27 will be described.

First, the CPU 25 initializes the initial value (the 0th value) of each variable calculated by the acceleration detecting means 15 and the calorific value calculating means 16. Specifically, the speed N (0) calculated by the speed calculating means 12, the digital filter 1
3, the average speed N '(0) calculated by the difference calculation unit 14, the acceleration A (0) calculated by the difference calculation unit 14, and the heat generation amount E (0) calculated by the heat generation amount calculation unit 16 are all set to zero. Also, CPU
Reference numeral 25 denotes an initial value of α (first constant) used by the calorific value calculating means 16 in the calorific value calculating process, for example, 12
Using the inertia of the cm-diameter disk, the value is temporarily set to a value calculated in advance by (Equation 6). Further, the CPU 25
Sets the initial value T (0) of the predicted temperature change value calculated by the temperature calculation means 20 to 0, and completes the initialization of each variable.

Next, the CPU 25 causes the timer 11 to start measuring time. The current instruction value generating means 18 is C
In order to rotate the disk motor 4 at a predetermined target rotation speed based on a command from the PU 25, the target rotation speed is compared with the rotation speed at that time, and a current command value corresponding to the magnitude of the difference is calculated. Output to the motor driving means 17. However, since the disk motor 4 is stopped at the time of startup, the current instruction value generation means 18 gives the motor drive means 17 a maximum current instruction value which can be set so that rotation can be started at the maximum rotational acceleration. Thereby, the motor driving means 2
Current is supplied to the disk motor 4 from 1 and the disk motor 4 starts rotating. When the rotation speed reaches the target rotation speed, the current instruction value generation means 18 reduces the current instruction value to a value required for rotating the disk motor 4 at a constant speed, and stabilizes the rotation speed of the disk motor 4 to the target rotation speed. Let it.

On the other hand, the CPU 25
Is driven to move the optical head 5 to a predetermined position on the inner circumference of the optical disc 2. The drive of the head transfer motor 7 may be controlled using a motor control device similar to the motor control device 27 that controls the drive of the disk motor 4. Next, when the rotation of the disk motor 4 starts, the optical head 5
To start reading signals from the optical disk 2. The read signal is converted into a binary signal by the head signal processing circuit 22 and input to the synchronous clock generation unit 23. Since the synchronous clock generating means 23 can generate a synchronous clock only in a predetermined rotation speed range (a range different for each radial position of recording / reproduction), the disk motor 4
Immediately after startup, the rotation speed is small and a synchronous clock cannot be generated, but the disk motor 4 enters the range of rotation speeds that can be generated as the rotation speed increases. When the synchronizing clock can be generated, the signal processing means 24 can generate a data signal from the binary signal output from the head signal processing circuit 22 and the synchronizing clock, thereby enabling a reproducing operation. The disc type is determined based on the data signal created by the signal processing means 24 in this way, and parameters and the like necessary for control are set for each type of disc based on the result.

Further, the inertia discriminating means 26 includes an α used by the calorific value calculating means 16 in the process of calculating the calorific value E (i).
(First constant) is reset to a predetermined value for each disc type (for example, for an 8 cm disc, a value calculated by changing the value of J in (Equation 6) according to the inertia of the disc). .

When the disk motor 4 starts rotating and the displacement measuring means 10 starts outputting pulses, the speed calculating means 12, the digital filter 13, the difference calculating means 14, and the calorific value calculating means 16 calculate the speed N, the average The calculation of each variable such as the speed N ′, the acceleration A, and the calorific value E is started.

FIG. 2 is a time chart showing a process in which the rotational speed of the disk motor 4 increases at a constant acceleration. FIG. 2 shows the speed N (n), the average speed N ′ (n), and the acceleration with respect to the pulse generated by the displacement measuring unit 10.

The speed calculating means 12 obtains the elapsed time Δtp (n) between the pulses generated by the displacement measuring means 10 from the time measuring means 11 and calculates the speed N (n) for each pulse generation according to (Equation 1). I do. The calculated speed N (n) usually includes an error with respect to the actual speed due to a variation in the magnetizing interval of the magnet 31 or the like. The digital filter 13 calculates an average speed N ′ (n) from which the error high frequency component of the speed N (n) has been removed, according to (Equation 3). The difference calculating means 14 calculates the average speed N ′ (i) and the elapsed time Δt
From (i), the acceleration A (i) is calculated according to (Equation 4). Here, j = 1, and the acceleration A (i) is calculated each time one pulse is generated, so i = n. Here, when the acceleration A (i) is calculated using the speed N (n) instead of the average speed N ′ (n), the acceleration A (i) is calculated using the average speed N ′ (n) as shown in FIG. In comparison, the error with respect to the actual acceleration becomes extremely large. By calculating the acceleration at the average speed N ′ (n) instead of the speed N (n), the calculation error can be greatly reduced, and the calculation of the heat generation amount and the prediction of the temperature rise can be performed with high accuracy. Will be possible.

Referring back to FIG. Calorific value calculation means 16
Calculates the heat value E (i) of the disk motor 4 using the detected acceleration A (i) according to (Equation 5).
In (Equation 5), the calculation accuracy of the calorific value is improved in consideration of not only the calorific value of the motor coil 29 calculated from the acceleration but also the frictional calorific value due to the bearing load of the motor. Note that the acceleration is calculated every time the displacement measuring means 10 generates a pulse, and thus corresponds to j = 1. Further, the calorific value of friction is calculated by multiplying the unit angle D displaced per pulse by the bearing load torque Tm of the disk motor 4. Further, the calorific value E by the calorific value calculating means 16 is obtained.
The calculation of (i) can always be performed during the operation of the optical disc device 1.

Next, the temperature calculating means 20 determines the timing immediately before the seek operation described later (when the seek operation is not performed for a long time, the heat generation amount E becomes larger than a predetermined value at regular intervals or at a certain time interval). ), The temperature change predicted value T (k) is calculated according to (Equation 9). This makes it possible to always predict the temperature rise of the disk motor 4 with high accuracy and control the operation of the disk motor 4 at an appropriate timing.

After calculating the predicted temperature change value T (k), the CPU 25 initializes the heat value E (k) to zero.
This initialization operation can prevent the digital value of the heat generation amount E from saturating due to excessive accumulation of the heat generation amount E.

With the above operation, the initial start-up operation of the optical disk device 1 is completed. Thereafter, the optical disk device 1 is in a state of waiting for a request for recording / reproducing information from the host device 28, and upon receiving a request from the host device 28, performs recording and reproduction of information.

Next, in order to record / reproduce information at a desired radial position on the optical disk 2, the optical head 5 is moved to the optical disk 2.
The operation at the time of the seek, which is carried in the radial direction of the above, will be described.

First, when a request for recording or reproduction of information is issued from the host device 28, the CPU 25 calculates a target position indicating where the recording or reproduction is to be performed on the optical disk 2, and controls the head transfer motor 7 to operate. The optical head 5 is driven to move to the target position. At the same time, the CPU 25 notifies the current instruction value generating means 18 of the target position. The current instruction value generating means 18 controls the disc motor 4 at the target position.
Is calculated as the target rotation speed.

In a CLV optical disk, during a seek operation, it is necessary to change the rotational speed of the disk motor 4 to a target rotational speed predetermined for each target position. Since a large current is supplied, if the seek operation is continuously performed for a long time, the disk motor 4 will be heated to a high temperature due to the heat generated by the supply of electric current. Therefore, before the rotation acceleration / deceleration of the disk motor is started, the temperature is calculated by the temperature calculating means 20, and the motor driving method is changed based on the result.

The operation of the case where the predicted temperature change calculated by the temperature calculating means 20 is high and low will be described below.

FIG. 3 shows a case where the predicted value of the temperature change is small.
1 of rotation fluctuation of disk motor 4 during seek operation
It is a time chart which shows an example.

FIG. 3 shows that the disk motor 4 is rotating at a constant rotation speed θa0 at the beginning, and during the seek operation,
In order to perform recording / reproduction on the inner circumference side of the optical disc 2,
The figure shows a state in which the target rotation speed is set to a higher rotation speed θa1 and acceleration is performed. The rotation speed of the disk motor 4 can be calculated by the speed calculation means 12. Also, CP
The U 25 determines the rotational speed of the disk motor 4, the temperature change in an arbitrary area in the optical disk device 1, the state of the operation of the optical head 5, and the like, and issues various operation commands to each component included in the optical disk device 1. obtain. The temperature rise is small immediately after the optical disk device 1 starts operating, and the temperature change threshold value Tth
If the predicted temperature change value T is smaller, the CPU 2
5 instructs the current limiting means 19 not to limit the drive current. As a result, the maximum current instruction value (Imax) that can be set is output to the motor driving means 17, and
A corresponding drive current is supplied from the motor drive unit 17 to the disk motor 4, and the disk motor 4 starts accelerating at the maximum rotational acceleration (period ta1). Here, the transfer of the optical head 5 is also started at the same time, but usually, the time required for the optical head 5 to be moved to the target position is much shorter than the fluctuation time of the rotation speed of the disk motor 4, and the optical head 5 seeks. Immediately after the operation starts, the transfer to the target position is completed.

Next, as the rotation speed of the disk motor 4 gradually increases, the rotation speed becomes a rotation speed range (θa2 to θa1) in which a synchronous clock can be generated, and the synchronous clock is output from the synchronous clock generating means 23. Become. When the reproducing operation is being performed, after the synchronous clock is output, the data signal is generated by the signal processing means 24, whereby the reproducing operation can be started. C
After confirming that the reproducing operation has become possible, the PU 25 instructs the current limiting means 19 to limit the driving current and notifies the limiting value Ia. As a result, the current value supplied to the disk motor 4 is limited, and the rotation speed increases slowly (period ta2). At this point, since the rotation speed is within the reproducible rotation speed range, the signal processing means 24 can continue the reproduction operation without any problem. Further, heat generation can be suppressed by reducing the value of the current supplied to the disk motor 4, so that the temperature rise can be reduced without adversely affecting the reproducing operation.

Since the calorific value calculating means 16 calculates the calorific value by measuring the rotational acceleration of the disk motor 4, even if the current value supplied to the disk motor 4 changes during the seek operation, there is no influence. It is possible to continue calculating the calorific value accurately without receiving it.

The lower limit of the rotational speed range in which the synchronous clock can be generated is the rotational speed range θa2 in which recording / reproduction is possible.
It may be a value lower than the lower limit θa2 of ~ θa1. For example, a rotation speed range in which a synchronous clock can be generated may be a range of θa4 to θa1 shown in FIG. Θb4, θc4, and θ shown in FIGS. 4, 8, and 9 described below.
d4 also indicates that the lower limit of the rotation speed range in which a synchronous clock can be generated may be lower than the lower limit of the rotation speed range in which recording / reproduction can be performed.

The rotation speed of the disk motor 4 falls within the rotation speed range (θa2 to θa1) in which a synchronous clock can be generated, and a slight time lag occurs between the output of the synchronous clock and the start of the reproducing operation. Occurs.
During this time lag, the disk motor 4 keeps accelerating. In the present embodiment, the drive current is limited at the time when the reproducing operation becomes possible. However, the drive current may be limited at the time when the synchronous clock can be generated. Since the drive current is limited, heat generation can be further suppressed. Further, even when the lower limit of the rotation speed range in which the synchronous clock can be generated is lower than the lower limit of the rotation speed range in which recording / reproduction can be performed, heat generation can be further suppressed.

Also, the acceleration and deceleration of the rotation speed of the disk motor 4 is moderated from the middle, so that the operation of the signal processing means 24 until the start of the reproducing operation can be performed stably, and after the synchronous clock can be generated. It is possible to shorten the time until the reproduction operation starts.

If the drive current is limited within the range of the rotational speed at which the synchronous clock can be generated or the range of the rotational speed at which recording / reproduction can be performed, the time required to reach the target rotational speed becomes longer.
At the time of acceleration, the time for recording / reproducing at a low rotation speed becomes longer, and the transfer rate (the amount of information recorded / reproduced per time) becomes lower. However, at the time of deceleration, conversely, the time required for recording / reproducing at a higher rotation speed than the target rotation speed becomes longer, and the transfer rate becomes higher. As an average operation, the transfer rate hardly decreases and only heat generation can be suppressed. It is.

If the rotational speed of the disk motor 4 before the start of the seek operation is already within the rotational speed range in which the synchronous clock can be generated or the rotational speed range in which recording / reproduction can be performed, immediately after the start of the seek operation. Drive current is limited.

In the case of the recording operation, the rotation speed range in which the recording operation can be performed may be different from that during the reproduction, and the timing for limiting the drive current may be different, but otherwise the same operation is performed.

Further, when the amount of information requested to be recorded / reproduced from the host device 28 is small and before the rotation speed of the disk motor 4 matches the target rotation speed θa1, recording / reproduction of the requested information amount is performed. When the recording is completed, the motor control means 21 changes the target rotation speed to the rotation speed of the disk motor 4 at the time when the recording / reproduction is completed (at the end of the period ta2), as shown in FIG. I do. As a result, the rotation speed of the disk motor 4 stops increasing, and the disk motor 4 is kept rotating at the rotation speed (θa3) at that time. The recording /
An unnecessary operation of continuously accelerating or decelerating the disk motor 4 even after the reproduction is completed can be eliminated, and the heat generation of the disk motor 4 can be suppressed and the temperature rise can be suppressed.

When the amount of information requested to be recorded / reproduced from the host device 28 is large, the disk motor 4 may be accelerated until the rotation speed of the disk motor 4 matches the target rotation speed θa1. If recording / reproduction of the requested information amount is not completed even when the rotation speed of the disk motor 4 reaches the target rotation speed θa1, recording / reproduction is performed with the rotation speed of the disk motor 4 kept at the target rotation speed θa1. Can be continued.

When the recording / reproduction is completed, the disk motor 4 is set to a high rotation speed when the acceleration is continued when the acceleration is being performed and the deceleration is stopped when the acceleration is being decelerated. Can be maintained, and the transfer rate can be improved.

Next, the seek operation when the predicted temperature value is large will be described.

FIG. 4 is a time chart showing an example of the fluctuation of the rotation of the disk motor 4 during the seek operation when the temperature rise is large.

In FIG. 4, first, the disk motor 4 is rotating at a constant rotation speed θb 0, and then, in a seek operation, a higher rotation speed θb 1 is required to perform recording / reproduction on the inner circumference side of the optical disk 2. Shows a state in which the target rotation speed is set and accelerated. When the predicted temperature change value T calculated by the temperature calculation means 20 immediately before the seek operation is larger than the temperature change threshold value Tth, regardless of the rotational speed range (θb2 to θb1) at which the synchronous clock can be reproduced. The drive current is limited immediately after the start of the seek operation (current instruction value Ib). Furthermore, the limit value Ib is set smaller as the temperature change predicted value T is larger. Thus, during the seek operation, the disk motor 4 can be operated with the current supplied to the disk motor 4 always kept small, and the temperature rise can be prevented.

FIG. 5 is a time chart showing an example of the relationship between the predicted temperature change value and the current instruction value.

When the predicted temperature change value T calculated immediately before the seek operation exceeds the temperature change threshold value Tth, the limit value of the drive current is changed from the limit value set at the previous seek in accordance with the difference. Set smaller. For example, the seek operation is continuously performed, and when a certain seek operation is completed, the temperature change predicted value T is slightly lower than the temperature change threshold value Tth, and in the next seek operation, the temperature change predicted value T increases greatly. When the threshold value Tth is greatly exceeded, the limit value of the drive current is set to a small value to suppress heat generation. When the temperature change predicted value T slightly exceeds the temperature change threshold value Tth, the drive current limit value is also set slightly smaller, and the temperature change predicted value T is changed to the temperature change threshold value Tt.
converge near h.

As shown in FIG. 5, the difference between the temperature change predicted value calculated immediately before a certain seek operation and the temperature threshold value Tth is ΔT1, and the current instruction value is changed by a predetermined value (ΔI1). Suppose that it is set small. At this time,
In the subsequent seek operation, if the difference ΔT2 between the temperature change predicted value T immediately before the seek operation and the temperature threshold value Tth is larger than the previous temperature predicted value ΔT1, the current instruction value reduction ΔI1 is further increased. The current instruction value is set smaller by the larger ΔI2. As a result, even if the relationship between the current instruction value and the current actually supplied to the disk motor 4 fluctuates variously due to variations in individual differences and the like of the motor driving means 17, the temperature change is not changed. It is possible to converge near the threshold value Tth.

As described above, according to the first embodiment of the present invention, the current flowing through the motor coil 29 of the disk motor 4 is determined by J · A (i) / K based on the acceleration A (i).
t (where J is the inertia and Kt is the torque constant of the motor). Since the torque constant Kt, which is a proportional constant between the motor torque and the drive current, takes a constant value in most of the operating range and has little variation,
There is always a proportional relationship between the acceleration A (i) and the current,
Regardless of the value of the acceleration A (i), an accurate current value can be calculated.

Further, since the normally used optical disk 2 is molded with high precision so as to meet a predetermined standard, there is almost no calculation error of the current value due to the inertia variation except when the disk diameter is different. Further, when the disk diameter is different, the first constant α is changed to a value corresponding to the inertia according to the size of the disk diameter, so that an accurate current value can always be calculated.

In calculating the acceleration A (i), the speed N (n) is output from the digital filter 13 instead of the speed N (n) itself calculated from the output pulse of the speed calculating means 12. Average speed N '
(N) is used. As a result, the speed calculation means 1
Even when the second output pulse contains a large amount of error, its influence can be greatly reduced and the calculation accuracy of the acceleration A (i) can be improved, so that the accurate current value can be calculated.

Since not only the heat generated by the motor coil 29 but also the heat generated by the bearing friction of the disk motor 4 is calculated, the amount of heat generated by the disk motor 4 can be more accurately predicted.

Further, at each seek operation, the limit value of the drive current is calculated from the limit value at the previous seek in accordance with the difference between the predicted temperature change value T (k) and the preset temperature change threshold value Tth. Can be changed. For this reason, even if the input / output gain of the motor drive means 17 fluctuates variously due to characteristic variations or the like, the temperature change can be converged to the vicinity of the temperature change threshold Tth.

If the rotational speed of the disk motor 4 is in a range where recording / reproduction is not possible during the seek operation, the disk motor 4 is accelerated / decelerated at the maximum acceleration.
After entering the recordable / reproducible range, the disk motor 4
Is limited, so that the time required to reach a recording / reproducing state does not become extremely long,
Heat generation of the disk motor 4 can be suppressed.

In the seek operation, if recording / reproduction is completed during acceleration / deceleration of the disk motor 4, the acceleration / deceleration is stopped at that time, so that the time for supplying a large current to the disk motor 4 is reduced. However, unnecessary heat generation can be prevented.

When the predicted temperature change value exceeds the temperature threshold value Tth during the seek operation, the limit value of the drive current is always reduced, so that a greater temperature reduction effect can be obtained. It is possible to prevent a temperature rise.

In the present embodiment, the digital filter 13 uses the calculation formula shown in (Equation 3). However, the present invention is not limited to this, and for example, the following (Equation 1)
The average speed may be calculated as shown in 0).

N ′ (n) = (N (n) + N (n−1)... + N (nm)) / m (Equation 10) In the present embodiment, this is expressed by (Equation 7). Acceleration A
The heat value E1 (i) of the motor coil 29 is calculated using (i). However, in the calculation process, the acceleration A
It is not necessary to calculate in the form of (i). For example, a motor coil is calculated by a calculation method such as the following (Equation 11) using, for example, a speed difference value having a meaning physically equivalent to acceleration. Even if the calorific value of 29 is calculated, the same effect can be obtained.

E1 (i) = α · (N ′ (ji · i) −N ′ (j · (i−1)) ² / Δt (i) (Equation 11) In this embodiment, As shown in (Equation 4), the acceleration A
(I) is calculated for every j pulses generated by the displacement measuring means 10, but j need not always be the same value, and may be dynamically changed during operation.

(Second Embodiment) FIG. 6 is a schematic configuration diagram of an optical disk device 41 according to a second embodiment of the present invention.

In contrast to the optical disk device 1 according to the first embodiment shown in FIG. 1, in the optical disk device 41, an acceleration detecting means (acceleration detecting device) 42 in a motor control device 43 is provided.
Does not include a digital filter. Other components are the same as those of the optical disk device 1.

In the acceleration detecting means 42, the speed calculating means 12 and the difference calculating means 14 calculate the acceleration A (i) from the speed N (n) of the disk motor 4 according to (Equation 1) and the following (Equation 2). Then, it outputs to the calorific value calculating means 16.

A (i) = (N (j · i) −N (j · (i−1))) / Δt (i) (Equation 2) j is a predetermined integer. In the embodiment, j is an integer which is an integral multiple of the number of pulses generated by the displacement measuring means 10 during one rotation of the disk motor 4, and is a multiple of 6, for example, when six pulses are generated in one rotation. Δt (i)
Is the elapsed time between the j · i-th pulse and the j · (i−1) -th pulse generated by the displacement measuring means 10. The process of calculating the predicted temperature change value T (K) from the acceleration A (i) is the same as in the first embodiment.

The motor control device 43 configured as described above
Disk device 4 equipped with motor and motor control device 43
1 will be described.

The CPU 25 initializes each variable, the disk motor 4 starts rotating, and the speed calculating means 12 sets the speed N
The operation up to the calculation of (n) is the same as in the first embodiment.

After the speed N (n) is calculated by the speed calculating means 12, the acceleration detecting means 42
Is used to calculate acceleration A (i) according to (Equation 2). J in (Equation 2) is set to an integral multiple of the number of pulses generated by the displacement measuring means 10 during one rotation of the disk motor 4. Therefore, acceleration A
The calculation of (i) can be performed based on a pulse always generated from the same magnetic pole among a plurality of magnetic poles magnetized on the magnet 31 provided in the disk motor 4.

For example, when a pulse generated from a magnetic pole having a magnetization error corresponds to a displacement of an angle D + e (e is an error component), and a pulse generated subsequently corresponds to a displacement of an angle De. In consideration of the above, if the rotation is performed at a constant speed at the rotation speed N0, the speeds measured by (Expression 1) are (Expression 12) and (Expression 13), respectively, and the actual rotation speed N
There is an error with respect to 0.

N0 · D / (D + e) (Equation 12) N0 · D / (D−e) (Equation 13) When the acceleration is calculated based on the speed calculated from these consecutive pulses, Is actually rotating at a constant speed and has an acceleration of 0
However, there is a speed difference and the calculation result has an acceleration.

However, in the present embodiment, the rotation speed is calculated based on the pulse generated from the same predetermined magnetic pole among the plurality of magnetized magnetic poles. In this case, even if a predetermined magnetic pole has a magnetization error, the same magnetization error is reflected in each pulse. For example, when the error component is + e, the rotation speed is calculated by a pulse corresponding to the displacement of the angle D + e, so that the calculated rotation speed is equal to the actual speed by D / (D + e).
Multiplied. Therefore, the speed difference calculated based on these speed calculation results becomes zero if the disk motor 4 is rotating at a constant speed, and the acceleration can be correctly calculated as zero.

As described above, according to the present embodiment, the disk motor 4 is an integral multiple of one rotation (for example, 1 or 2 times).
By calculating the acceleration based on the pulse generated each time the rotational displacement is doubled, it is possible to completely eliminate the acceleration calculation error caused by the variation of the magnetization interval.

FIG. 7 is a time chart showing a change in rotation speed when the disk motor 4 repeats acceleration / deceleration.
As shown in FIG. 7, according to the present embodiment, even when the actual speed of the disk motor 4 repeats sudden acceleration / deceleration,
It is possible to calculate the acceleration A (i) with high accuracy that substantially matches the actual acceleration.

If the variation in the magnetizing interval of the magnet 31 of the disk motor 4 is large, a low-pass filter is applied to the speed N (n), and the cut-off frequency of the low-pass filter is lowered to reduce the error caused by the variation. Can be reduced. However, on the other hand,
As shown in FIG. 7, when the acceleration / deceleration of the disk motor 4 is sharply changed due to rapid rotation acceleration / deceleration, the calculated acceleration value cannot follow the actual acceleration, resulting in a time delay. In particular, at a high rotation speed at which heat generation becomes a problem, the influence of the variation of the magnetization interval appears as an error, so that it is necessary to lower the cutoff frequency of the low-pass filter, which further increases the time delay. However, if the acceleration is calculated based on a pulse generated when performing a rotational displacement of an integral multiple of one rotation as in the present embodiment,
The influence of the variation of the magnetization interval can be almost eliminated. At this time, although a time delay of one rotation occurs in the acceleration detection, the influence of the time delay becomes smaller at a higher rotation speed at which heat generation becomes a problem, so that extremely accurate acceleration detection is possible.

When the pulse used for detecting the acceleration is selected from the pulses generated during one rotation of the disk motor 4, the speed calculated by (Equation 1) is set to 1 for each pulse generated. The speed calculation accuracy and the acceleration detection accuracy can be further improved by averaging only the number of rotations (or an integer number of rotations) and using a pulse whose speed is closest to the average speed.

It should be noted that, based on the detected acceleration,
The operations of the calorific value calculation means 16 and the temperature calculation means 20 are the same as in the first embodiment.

Next, in order to record / reproduce information at a desired radial position on the optical disk 2, the optical head 5 is moved to the optical disk 2.
The operation at the time of seek, which moves in the radial direction, will be described.

FIG. 8 is a time chart showing an example of the fluctuation of the rotation of the disk motor 4 during the seek operation.

First, when a request for recording or reproduction of information is issued from the host device 28, the CPU 25 calculates a target position indicating where the recording or reproduction is to be performed on the optical disk 2, and controls the head transfer motor 7 to operate. Drive to optical head 5
To the target position. At the same time, the CPU 25 notifies the current instruction value generating means 18 of the target position. The current instruction value generating means 18 calculates the required rotation speed of the disk motor 4 at the target position as the target rotation speed (θc1). At this time, the temperature change predicted value T calculated by the temperature calculation means 20 is lower than the temperature change threshold value Tth, and the rotation speed θc0 before the seek operation falls within the rotation speed range (θc2 to θc1) where recording / reproduction is possible. If not, CPU
25 instructs the current limiting means 19 not to limit the drive current. Thereby, the motor driving means 17
, A settable maximum current instruction value (Imax) is output, and a corresponding drive current is supplied from the motor drive unit 17 to the disk motor 4, and the disk motor 4 starts accelerating at the maximum rotational acceleration. (Period tc1).

Next, when the rotational speed of the disk motor 4 is θc
2 and a synchronous clock can be generated.
When the recording / reproducing operation becomes possible, the current instruction value generating means 18 sets the target rotation speed to θc2 for a predetermined period (tc2), for example, about 50 ms, and then sets the target rotation speed to θc1 again. Set again. As a result, the disk motor 4 temporarily stops accelerating, rotates at a constant rotation speed θc2 for a predetermined time, and then accelerates again to a rotation speed θc1 (tc3).

The operation of stopping the acceleration / deceleration of the disk motor 4 for a predetermined time when the recording / reproducing rotation speed is within the above-mentioned rotational speed range is performed. It is possible to suppress the rise.

In the period tc3, the current limiting means 19
Limits the drive current, and the current instruction value is limited to Ic. Therefore, it is possible to reduce the drive current supplied to the disk motor 4 and suppress a rise in temperature.

Next, referring to FIG. 9, the target rotation speed during the seek operation is set to θd lower than rotation speed θc1 shown in FIG.
The operation in the case of 1 will be described. FIG. 9 is a time chart showing another aspect of the rotation fluctuation of the disk motor 4 during the seek operation.

In FIG. 9, operations in periods td1 and td2 are the same as those in FIG. During a period (td3) of acceleration in the rotational speed range (θd1 to θd2) at which recording / reproduction is possible, the current limiting means 19 limits the drive current. At this time, the current limiting value set by the current limiting means 19 is limited. The value Id is set differently depending on the height of the target rotation speed (θd1), and the higher the target rotation speed is, the larger the limit value of the drive current is set. For example, since the target rotation speed θc1 in FIG. 8 is higher than the target rotation speed θd1 in FIG. 9, the limit value Ic of the current instruction value is higher than Id. Normally, the frictional force with the air generated when the optical disk 2 rotates increases as the rotational speed increases, and to control the disk motor 4 at a high target speed, motor torque is required more than at a low rotational speed. Requires a large drive current. If the limit value of the drive current is small, it may take a long time to reach the target rotation speed, or the drive current may not reach the target rotation speed. Therefore, in a period (td3) immediately before the rotation speed of the disk motor 4 reaches the target rotation speed, it is necessary to increase the drive current limit value as the target rotation speed increases. Thus, no matter what the target rotation speed is, the rotation speed of the disk motor 4 can be settled to the target rotation speed in a short time, and a stable operation can be realized.

In the present embodiment, the current limiting means 19 limits the drive current after the CPU 25 confirms that recording / reproduction has become possible. However, the confirmation operation of the CPU 25 may be omitted. In this case, after the CPU 25 instructs the target rotation speed to the current instruction value generation means 18, the current instruction value generation means 18 calculates a recording / reproducing rotation speed range from the target rotation speed and notifies the current limitation means 19. I do. At the time of the seek operation, the current limiting means 19 monitors the rotational speed of the disk motor 4 and, if the rotational speed falls within a previously calculated rotational speed range for recording / reproduction, the drive current is limited. In this case, the control performed by the CPU 25 can be simplified. Further, before the start of the seek, it can be determined whether or not the rotational speed at that time falls within the rotational speed range where recording / reproduction is possible. At this time, if the rotation speed is within the recording / reproducing rotation speed range, the rotation speed is kept constant immediately after the start of the seek operation, and the acceleration / deceleration of the disk motor 4 is started at the timing when the transfer of the optical head 5 is completed. Accordingly, particularly when the seek operation is continuously performed, the heat generation of the disk motor 4 can be largely suppressed.

As described above, the operation of stopping the acceleration / deceleration of the disk motor 4 for a predetermined time within the rotational speed range in which recording / reproduction is possible can reduce the time during which a large current flows through the disk motor 4 and reduce the amount of heat generated. It is possible.

In this embodiment, during acceleration / deceleration in the rotational speed range where recording / reproduction is possible (periods tc3 and tc3).
d3) is the upper limit of the current instruction value range (Ic and Id)
Is always constant, for example, the drive current limit values Ic and Id are set just before the target rotational speed is settled.
In other periods, a smaller limit value may be set, and in this case, the amount of generated heat can be further reduced.

As described above, according to the second embodiment of the present invention, the calculation of the acceleration A is performed at the timing when the disk motor 4 makes a rotational displacement of an integral multiple of one rotation.
At this time, acceleration is calculated based on a pulse generated from a specific magnetic pole in the magnet 31 of the disk motor 4, and it is possible to remove an error due to a variation in the magnetization interval between the magnetic poles. It is possible to realize highly accurate acceleration calculation with a small amount, and to greatly improve the prediction accuracy of the temperature rise.

In the seek operation, if the rotation speed of the disk motor 4 enters the rotation speed range in which recording / reproduction can be performed, the acceleration / deceleration is stopped for a predetermined period of time. Can be suppressed.

Further, since the limit value of the drive current in the recording / reproducing rotation speed range is set to be higher as the target rotation speed is higher, the rotation speed of the disk motor 4 can be set at a higher target rotation speed. It is possible to settle in a short time and to set a low target speed.
It is possible to suppress a temperature rise.

Further, the CPU 25 and the inertia discriminating means 26 provided in the motor control devices 27 and 43 shown in the first and second embodiments may be provided outside the motor control devices 27 and 43.

In the acceleration detecting means 42, it is preferable that the speed is calculated based on a pulse generated each time the disk motor 4 makes a rotational displacement of an integral multiple of one rotation. The amount is the disk motor 4
Is not limited to an integral multiple of one rotation of
It may be any multiple of the rotation.

Further, the displacement measuring means 1 in the present embodiment
It is possible to configure a speed detecting device 33 that calculates the speed of the disk motor 4 by using 0, the time measuring unit 11 and the speed calculating unit 12. The acceleration detecting means 4 described above
Similarly to 2, according to the speed detecting device 33, the speed is calculated based on a pulse generated each time the disk motor 4 makes a rotational displacement of an integral multiple of one rotation (for example, one or two times). It is possible to completely eliminate the speed calculation error caused by the variation of the magnetization interval.

[0169]

As described above, according to the motor control device of the present invention, the calorific value of the motor (motor coil 29) is calculated based on the rotational acceleration of the motor having a proportional relationship with the drive current of the motor. In addition, even if the magnitude of the drive current changes, the heat generation amount can be accurately predicted from the rotational acceleration, and the temperature can be predicted with high accuracy. Further, since the motor is controlled based on the accurate prediction of the temperature change, it is possible to prevent the heating and the destruction of parts due to the temperature rise.

According to the present invention, the calorific value is calculated by adding the calorific value of the motor coil based on the acceleration and the calorific value by the bearing friction based on the rotational displacement. And a motor control device capable of predicting a high temperature change.

According to the present invention, the acceleration is calculated from the speed every time the motor makes a rotational displacement of an integral multiple of one rotation, so that the acceleration caused by the variation in the magnetization interval of the magnets provided in the motor is calculated. A highly accurate acceleration detection device capable of completely eliminating a calculation error is provided.

Further, according to the present invention, even when an optical disk having a different diameter is driven, the calculation method for calculating the heat generation amount from the acceleration is changed based on the difference in inertia. A possible motor control is provided.

Further, according to the present invention, when the rotation speed of the motor is in the rotation speed range where recording / reproduction is possible, and when the predicted temperature change exceeds a preset threshold value,
Since the drive current is limited, the amount of heat generation is suppressed, and an optical disk device with a small temperature rise is provided.

Further, according to the present invention, the limit value of the drive current is changed in accordance with the amount by which the temperature change calculated by the temperature calculation means exceeds the threshold value. Provided is an optical disk device capable of converging a temperature change to a threshold value or less even if there is variation.

According to the present invention, when the motor is accelerating or decelerating at the time when the recording or reproduction is completed and the motor is in a standby state, the acceleration / deceleration is stopped. Provided is an optical disk device in which the amount of heat generation is suppressed and the temperature rise is small.

Further, according to the present invention, when the rotation speed of the disk is in the range where recording / reproduction is possible, a period for keeping the rotation speed constant is provided. An optical disk device capable of suppressing the temperature rise and reducing the temperature rise is provided.

Further, according to the present invention, the upper limit value of the current instruction value range during the seek operation is set higher as the target rotation speed is higher, so that the rotation can be settled quickly even at a higher target rotation speed. An optical disk device capable of suppressing the amount of heat generation and reducing the temperature rise for a low target rotation speed is provided.

Further, according to the present invention, the magnetic flux measurement of the rotating rotor of the motor is performed by the displacement measuring means (the sensor section and the waveform shaping section). Such a displacement measuring means is provided in advance in a device that needs to grasp the number of rotations of the motor. Therefore, the calorific value can be calculated from the acceleration of the motor of the present invention by using such a displacement measuring means provided in advance, and it is necessary to newly provide a temperature sensor and a current detecting means as in the prior art. There is no. Therefore, according to the present invention, the configuration of the motor control device can be simplified, and the cost of parts and the number of assembly steps can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a motor control device and an optical disk device equipped with the motor control device according to a first embodiment of the present invention.

FIG. 2 is a time chart showing a process of increasing the rotation speed of the disk motor according to the first embodiment of the present invention.

FIG. 3 is a time chart at the time of a seek operation when a predicted temperature change value is small in the first embodiment of the present invention.

FIG. 4 is a time chart at the time of a seek operation when a predicted temperature change value is large according to the first embodiment of the present invention;

FIG. 5 is a time chart showing a relationship between a predicted temperature change value and a current instruction value in the first embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a motor control device and an optical disk device equipped with the motor control device according to a second embodiment of the present invention.

FIG. 7 is a time chart showing a process of repeating acceleration / deceleration of the disk motor in the present invention.

FIG. 8 is a time chart in a seek operation with a high target rotation speed in the second embodiment of the present invention.

FIG. 9 is a time chart in a seek operation with a low target rotation speed in the second embodiment of the present invention.

FIG. 10 is a diagram showing a conventional disk device.

FIG. 11 is a diagram showing a relationship between a current instruction value in a motor driver IC and a motor driving current.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 2 Optical disk 3 Turntable 4 Disk motor 5 Optical head 6 Guide shaft 7 Head transfer motor 9 Chassis 10 Displacement measuring means 11 Time measuring means 12 Speed calculating means 13 Digital filter 14 Difference calculating means 15 Acceleration detecting means 16 Heat generation amount calculating means Reference Signs List 17 motor driving means 18 current indicated value generating means 19 current limiting means 20 temperature calculating means 21 motor controlling means 22 head signal processing circuit 23 synchronous clock generating means 24 signal processing means 25 CPU 26 inertia discriminating means 27 motor control device 28 host device 41 Optical disk device 42 Acceleration detecting means (acceleration detecting device) 43 Motor control device

Claims (29)

[Claims] 1. An acceleration detecting means for detecting an acceleration of a motor, a motor driving means for supplying a driving current to the motor, and a calorific value calculation for calculating a calorific value of the motor based on at least an output of the acceleration detecting means. And a motor control means for controlling the motor driving means based on the heat generation amount. 2. The acceleration detecting means comprises: displacement measuring means for measuring a predetermined displacement of the motor; and time measuring means for measuring a time required for the predetermined displacement. The motor control device according to claim 1, wherein the acceleration is calculated based on an output of a measuring unit and an output of the timing unit. 3. The calorific value calculating unit holds a relationship between the acceleration and the calorific value, and calculates the calorific value based on at least the acceleration output from the acceleration detecting unit based on the relationship. 2. The motor control device according to 1. 4. The heat generation amount calculation means according to claim 2, wherein
Based at least on a first value of the power multiplied by a first constant,
The motor control device according to claim 1, wherein a calorific value of the motor is calculated. 5. The motor control according to claim 4, further comprising inertia determination means for determining inertia of a load when the motor is driven, wherein the first constant is changed by an output of the inertia determination means. apparatus. 6. The acceleration detecting means calculates a predetermined rotational displacement by multiplying the predetermined displacement by a predetermined integer, and the heating value calculating means multiplies a square of the acceleration by a first constant. At least based on a sum of a first value and a second value obtained by multiplying the predetermined rotational displacement by a second constant,
The motor control device according to claim 2, wherein a calorific value of the motor is calculated. 7. The motor control according to claim 6, further comprising inertia determination means for determining inertia of a load when the motor is driven, wherein the first constant is changed by an output of the inertia determination means. apparatus. 8. The acceleration detecting means, which measures a predetermined displacement of the motor, and generates a pulse for each of the predetermined displacements; a time measuring means for measuring an interval of generation of the pulse; and the motor And a speed calculating means for calculating a speed of the motor from an interval of the pulse each time a predetermined rotational displacement is performed by an integral multiple of the predetermined displacement, wherein the acceleration detecting means calculates the acceleration from the speed. The motor control device according to claim 1, which calculates: 9. The motor of claim 1, wherein the predetermined rotational displacement is one of
9. The motor control device according to claim 8, wherein the motor control device is equal to an integral multiple of a rotational displacement per rotation. 10. The acceleration detecting means includes: a displacement measuring means for generating a pulse each time the motor is displaced by a predetermined angle D; and a rotation of the motor each time the displacement measuring means generates the n-th pulse. A speed calculating means for calculating the speed N (n) by (Equation 1); and a difference calculation for calculating an i-th calculated acceleration A (i) by (Equation 2) every time the j pulses are generated. N (n) = D / Δtp (n) (Equation 1) A (i) = (N (ji · i) −N (j · (i−1))) / Δt (I) (Expression 2) where n, i and j are positive integers and Δtp
(N) is the elapsed time between the n-th pulse and the (n-1) -th pulse generated by the displacement measuring means, and Δt (i)
Is the j / i-th pulse generated by the displacement measuring means and j
The motor control device according to claim 2, wherein the elapsed time from the (i-1) th pulse is elapsed. 11. The motor control device according to claim 10, wherein the value of j is an integral multiple of the number of pulses generated by the displacement measuring means during one rotation of the motor. 12. The acceleration detection means receives a speed N (n) at which the motor is displaced, and receives an average speed N ′ (n).
And a digital filter that outputs the following equation:
Acceleration A using average speed N '(n) instead of (n)
The motor control device according to claim 10, wherein (i) is calculated. 13. The digital filter calculates the average speed N ′ (n) according to (Equation 3), and N ′ (n) = (N (n) + (m−1) · N ′ (n− 1)) / m (Expression 3) Here, the motor control device according to claim 12, wherein m is a positive integer. 14. A motor control unit, comprising: a temperature calculation unit that calculates at least one of a temperature change of the motor and a temperature change of a drive target of the motor based on a heat generation amount calculated by the heat generation amount calculation unit; Current limiting means for limiting a drive current output by the motor drive means, wherein when the temperature change exceeds a predetermined threshold, the motor control means sets a limit value of the drive current. 1
3. The motor control device according to claim 1. 15. The method according to claim 1, wherein the limit value is changed in accordance with an amount of the temperature change exceeding the predetermined threshold.
5. The motor control device according to 4. 16. A motor for rotating a disk, an optical head for recording information on the disk or reproducing information from the disk, motor driving means for supplying a driving current to the motor, A motor control unit to be set; a speed calculation unit to calculate a rotation speed of the motor; and a rotation speed of the motor within a rotation speed range that enables the optical head to record on or reproduce from the disk. Determining means for determining whether or not
When the determination unit determines that the rotation speed of the motor is within the rotation speed range that enables recording or reproduction from the disk by the optical head, the motor control is performed. Means for limiting the drive current. 17. The disk drive according to claim 16, wherein the motor control means sets a higher limit value of the drive current as the target rotation speed of the motor is higher. 18. The motor control unit according to claim 16, wherein before the rotation speed of the motor is settled at a target rotation speed, the drive current limit value is set to be higher than at the start of acceleration of the motor. The disk device according to item 1. 19. An acceleration detecting means for detecting an acceleration of the motor; a calorific value calculating means for calculating a calorific value of the motor based on at least the acceleration output from the acceleration detecting means; Temperature calculating means for calculating a temperature change in a predetermined area of the disk device, wherein the determining means further determines whether the temperature change is equal to or less than a predetermined threshold value, Is less than or equal to the predetermined threshold value, and when the determination unit determines that the rotation speed of the motor is within a rotation speed range that enables recording or reproduction by the optical head, the motor control unit Limits the drive current, and when the determination means determines that the temperature change is not below the predetermined threshold, the motor control means limits the drive current. The disk apparatus according to claim 16. 20. The disk device according to claim 19, wherein said motor control means sets a limit value of said drive current higher as a target rotation speed of said motor is higher. 21. The motor control means, before the rotation speed of the motor is settled at the target rotation speed, sets the limit value of the drive current higher than at the time of start of acceleration of the motor. The disk device according to item 1. 22. A motor for rotating a disk; an optical head for recording information on the disk or reproducing information from the disk; a motor driving unit for supplying a driving current to the motor; Motor control means for setting; synchronous clock generating means for generating a synchronous clock based on a reproduction signal read from the disk by the optical head; speed calculating means for calculating a rotational speed of the motor; Determination means for determining whether or not the rotation speed is within a range of rotation speed at which the synchronous clock generation means can generate the synchronous clock, and wherein the rotational speed of the motor is controlled by the synchronous clock generation means. If the determination unit determines that the rotation speed is within the rotation speed range that enables generation of a clock, the motor control Disk drive stage for limiting the drive current. 23. The disk device according to claim 22, wherein the motor control means sets a higher limit value of the drive current as the target rotation speed of the motor increases. 24. The motor control means sets the limit value of the drive current to be higher than at the start of acceleration of the motor before the rotation speed of the motor is settled at the target rotation speed. The disk device according to item 1. 25. A motor for rotating a disk, an optical head for recording information on the disk or reproducing information from the disk, a motor driving unit for supplying a driving current to the motor, Motor control means for setting; speed calculation means for calculating the rotation speed of the motor; and whether or not the optical head is performing recording to and reproduction from the disk, and the rotation speed of the motor changes. Determining means for determining whether or not the optical head is not recording on or reproducing from the disk, and the rotational speed of the motor is changing. If it is determined, the disk drive controls the drive current so that the rotation speed of the motor is constant. 26. A motor for rotating a disk, an optical head for recording information on the disk or reproducing information from the disk, a motor drive unit for supplying a drive current to the motor, and Motor control means for setting; head moving means for moving the optical head to a predetermined position on the disk where recording or reproduction is performed by the optical head; speed calculating means for calculating a rotation speed of the motor; Determining means for determining whether or not the rotation speed of the motor is within a rotation speed range at which recording or reproduction from the disk by the optical head is possible during a seek operation in which the head moves. During a seek operation in which the optical head moves, the rotation speed of the motor is controlled by the optical head to When the determination unit determines that the rotation speed is within the rotation speed range that enables recording on a disk or reproduction from the disk, the motor control unit determines that the rotation speed of the motor is constant for a predetermined time. A disk device for controlling the drive current. 27. A motor for rotating a disk, an optical head for recording information on the disk or reproducing information from the disk, motor driving means for supplying a driving current to the motor, A disk comprising: motor control means for setting; acceleration detection means for detecting acceleration of the motor; and heat generation amount calculation means for calculating a heat generation amount of the motor based on at least the acceleration output from the acceleration detection means. An apparatus, wherein the disk device is configured to calculate a temperature change in a predetermined area of the disk device based on the heat generation amount; and whether the temperature change is equal to or more than a predetermined threshold. Determining means for determining whether or not the temperature change is equal to or greater than the predetermined threshold value. Disk drive means for limiting the drive current. 28. A displacement measuring means for generating a pulse each time the motor makes a predetermined displacement; a time measuring means for measuring an interval of the generation of the pulse; and a predetermined rotational displacement which is an integral multiple of the predetermined displacement. Speed calculation means for calculating the speed of the motor based on the pulse generation interval, wherein the predetermined rotational displacement is equal to an integral multiple of the rotational displacement per rotation of the motor. Detection device. 29. An acceleration detection device comprising the speed detection device according to claim 28, wherein an acceleration is calculated from the speed.