JP2002034284A - Motor rotation detection system and disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optimum motor rotation detection system for detecting the rotation of a motor with a brush, a disk device, and an adjustment method. SOLUTION: According to the inertial rotation of the motor 510 with a brush that has not been driven, switching noise generated in a signal SMV and the level of an induced voltage are detected, and it is judged whether the rotation of the motor 510 has stopped or not. After the SMV is passed through a high- pass filter and is level-shifted, the switching noise is detected. Noise having a noise level exceeding hysteresis width is detected as the switching noise. When given target time passes after the switching noise is not detected, it is judged that the rotation of the motor has stopped. When an SMSIG is outputted from a monitor terminal 58, the hysteresis width is set to a hysteresis width-setting registor 46 while output is periodically made at the frequency of the switching nose, and a pulse intermittently disappears, the target time corresponding to the disappearance state is set to a target time-setting registor 54.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor rotation detection system, a disk drive, and a method for adjusting the motor rotation detection system.

[0002]

BACKGROUND ART Problems to be Solved by the Invention CD (Co
mpact Disc), DVD (Digital Versatile Disc, Digi)
2. Description of the Related Art In a disk device for reproducing and recording a disk such as a tal Video Disc) and a MOD (Magnet Optical Disc), a disk motor (spindle motor) for rotating the disk at a constant linear velocity is required. Conventionally, a so-called brushless motor has been frequently used as such a disk motor.

[0003] In this brushless motor, the brush and commutator (commutator) of an ordinary motor with a brush are removed, and the rotor of the motor is rotated by an electronic commutation mechanism. More specifically, the position of the magnet rotor is detected using a magnetic sensor such as a Hall element,
The electronic rectifier circuit is controlled based on the detection result to generate a rotating magnetic field and rotate the rotor.

However, this brushless motor is
The necessity of the Hall element and the electronic rectification circuit causes problems such as a complicated structure of the disk device and an increase in the cost of the device.

On the other hand, a brush motor that rectifies current by contacting and non-contact between a brush and a commutator eliminates the need for a Hall element or an electronic rectifier circuit, thereby simplifying the structure of a disk drive and reducing the cost of the drive. There is a merit that can be achieved. Therefore, in a disk device such as a DVD in which compactness and low cost of the device are strongly demanded, it is desirable to use a motor with a brush instead of the conventional brushless motor.

However, in a brushless motor, the rotation stop state of the motor can be detected based on a phase switching signal in an electronic rectifier circuit. However, in a motor with a brush, there is a problem that the rotation stop state cannot be detected by the motor alone.

Therefore, if a brush motor is used as a disk motor, it is impossible to determine whether the rotation of the motor stops when the disk is ejected (ejected), and the disk may be ejected in a rotating state.
As a result, the disk and the disk tray collide with each other, causing problems such as generation of abnormal noise and damage to the disk.

The present invention has been made in view of the above technical problems, and has as its object the most suitable for detecting the rotation of a motor that rectifies a current by contact and non-contact between a commutator and a brush. An object of the present invention is to provide a motor rotation detection system, a disk device using the motor rotation detection system, and an adjustment method most suitable for the motor rotation detection system.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is a system for detecting the rotation of a motor, which is generated at a drive terminal of the motor by the inertial rotation of the rotor of the motor in a non-driven state. Detection means for detecting switching noise superimposed on the induced voltage, which is generated by contact or non-contact between the commutator and the brush due to the inertial rotation of the rotor, and a detection result of the switching noise. Determining means for determining whether or not the rotation of the rotor of the motor has stopped.

According to the present invention, switching noise superimposed on the induced voltage (signal from the drive terminal) generated at the drive terminal of the motor in the non-drive state is detected, and based on the detection result, the switching noise of the motor is detected. A rotation stop determination is made. That is, even if the motor is in a non-driving state, the rotor of the motor continues to rotate due to inertia for a given time. Then, an induced voltage is generated at the drive terminal of the motor by the inertial rotation. Further, due to the contact or non-contact between the commutator and the brush due to the inertial rotation, switching noise is superimposed on the induced voltage generated at the drive terminal. In the present invention, the motor rotation stop determination is performed by paying attention to the existence of the switching noise which is generated even when the motor is in the non-drive state.

The main factor that changes the level of the switching noise is only the number of turns (inductance) of the coil of the motor. Therefore, if the rotation stop of the motor is determined using the switching noise, a determination process that is easy to adjust and has high stability can be realized.

Further, the present invention is characterized in that the detecting means performs a filtering process for passing a high-frequency component of a signal from a driving terminal of the motor, and detects switching noise superimposed on the filtered signal. And

As described above, by performing the process of passing the high frequency component of the signal from the drive terminal, the low frequency component that gradually reduces the level of the induced voltage generated at the drive terminal can be cut. Therefore, it is possible to easily perform the switching noise detection processing based on the switching noise level and the like, and it is possible to improve the accuracy of the motor rotation stop determination.

Further, the invention is characterized in that the detecting means shifts the level of a signal from a drive terminal of the motor to a given voltage level and detects switching noise superimposed on the signal after the level shift. I do.

By performing such a level shift, it is possible to obtain a signal in which switching noise occurs on the positive electrode side or the negative electrode side with reference to a given voltage. Therefore,
Switching noise detection processing based on the switching noise level and the like can be facilitated, and the rotation stop determination of the motor can be performed with high accuracy.

Further, the present invention is characterized in that the detecting means detects noise whose noise level exceeds a given hysteresis width as the switching noise.

In this way, it is possible to determine whether the noise is switching noise or other noise only by determining whether the noise level exceeds a given hysteresis width.

Further, the present invention is characterized in that it includes a hysteresis width setting means for setting the hysteresis width, and a monitor terminal which outputs a detection result of the detection means as a switching noise detection signal. .

By doing so, the monitor terminal (for example, I
While monitoring a switching noise detection signal output from a terminal of a semiconductor integrated device (e.g., C), an appropriate hysteresis width is determined, and the determined hysteresis width can be set in the hysteresis width setting means. Therefore, the adjustment work of the motor rotation detection system can be made more efficient.

Further, the invention is characterized in that the determining means determines that the rotation of the motor rotor has stopped after a given target time has elapsed since the switching noise was not detected.

In this way, even if switching noise is accidentally not detected due to, for example, a contact state between the commutator and the brush, it is not immediately determined that the rotation of the rotor has stopped. Become like Therefore, a more reliable rotation stop determination can be realized.

Further, the present invention is characterized in that it includes a target time setting means for setting the target time, and a monitor terminal for outputting a detection result of the detection means as a switching noise detection signal. .

With this arrangement, while monitoring the switching noise detection signal output from the monitor terminal,
It is possible to determine an appropriate target time and set the determined target time in the target time setting means. Therefore, the adjustment work of the motor rotation detection system can be made more efficient.

The present invention is also a system for detecting the rotation of a motor, comprising: a detecting means for detecting a level of an induced voltage generated at a drive terminal of the motor due to an inertial rotation of a rotor of the motor in a non-driven state; Determining means for determining whether or not the rotation of the rotor of the motor has stopped based on the detection result of the level of the induced voltage.

According to the present invention, the level of the induced voltage (back electromotive force) generated at the drive terminal of the motor in the non-drive state is detected, and based on the detection result, the rotation stop of the motor is determined. . That is, even if the motor is in a non-driving state, the rotor of the motor continues to rotate due to inertia for a given time. Then, an induced voltage is generated at the drive terminal of the motor by the inertial rotation. In the present invention, the motor rotation stop determination is performed by focusing on the presence of the induced voltage which is generated even when the motor is in the non-drive state.

According to the present invention, it is possible to determine whether or not to stop the rotation of the motor only by detecting the level of the induced voltage generated at the drive terminal, so that the configuration of the motor rotation detection system can be simplified.

According to the present invention, the determination means determines that the rotation of the rotor of the motor has stopped after a predetermined target time has elapsed after the level of the induced voltage has reached a predetermined voltage level. It is characterized by.

In this way, even when the given voltage level to be compared with the induced voltage fluctuates, erroneous determination can be prevented from being performed, and more reliable rotation stop determination can be realized. it can.

According to the present invention, there is also provided a disk device including any one of the above-described motor rotation detection systems, wherein the disk rotation control is performed based on a signal from a pickup which is servo-controlled so as to follow a track of the disk. And a motor driving means for driving the motor under the control of the disk servo control means.

As described above, when the motor rotation detection system of the present invention is used in a disk device, it is possible to solve problems such as generation of abnormal noise when the disk is taken out and damage to the disk. Performance can be improved.

Further, the present invention is characterized in that even when the disk servo control means does not detect the rotation stop of the disk, the disk rotation control unit detects the rotation stop of the disk based on the determination result of the motor rotation detection system. And

With this arrangement, even when servo control is lost due to a defect or fingerprint of the disk, the stop of the rotation of the disk can be properly detected, and the reliability of the disk device can be improved. Can be improved.

Further, the present invention is characterized in that prior to the disc type discriminating process, the disc rotation stop is detected based on the discrimination result of the motor rotation detection system.

In this way, it is possible to prevent the disc type discrimination process from being performed while the disc is rotating, and to implement a proper discrimination process.

According to the present invention, there is provided an adjusting method used in the motor rotation detecting system, wherein a pulse of a switching noise detection signal output from the monitor terminal is:
A hysteresis width when periodically output at the frequency of the switching noise is set in the hysteresis width setting means.

With this configuration, it is possible to determine a hysteresis width that allows only the switching noise to be extracted from the noise generated at the drive terminal, and to set an appropriate hysteresis width in the hysteresis width setting means.

According to the present invention, there is provided an adjusting method for use in the above-mentioned motor rotation detecting system, wherein the pulse of the switching noise frequency is intermittently lost among the pulses of the switching noise detection signal output from the monitor terminal. In this case, a target time according to the disappearance state of the pulse is set in the target time setting means.

In this way, if the pulse of the frequency of the switching noise intermittently disappears due to, for example, the contact state between the commutator and the brush, the target time considering the disappearance state is considered. Can be set in the target time setting means.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

1. FIG. 1 shows a configuration example of a disk device (optical disk device in a narrow sense) using the motor rotation detection system of the present embodiment.

The disk device shown in FIG. 1 includes a disk motor 510 (spindle motor) for rotating a rotating shaft on which a disk 500 such as a CD or DVD is mounted.

Below the disk 500, a pickup 530 (optical pickup in a narrow sense) is arranged, and the pickup 530 is mounted on a carriage 560 that moves in the radial direction of the disk 500.

The carriage 560 can be moved in the radial direction of the disk 500 by a feed mechanism (not shown), and the feed mechanism is driven by a feed motor 570.

The pickup 530 includes a semiconductor laser and a photodetector (not shown). Then, a laser beam from the semiconductor laser is applied to the disk 500 via the objective lens 520, and the reflected light is received by a light receiving portion of the photodetector divided into four or two.

Objective lens 520 of pickup 530
Is held so as to be finely movable along the optical axis direction (vertical direction) and is also finely movable in the radial direction of the disk 500. Then, the focus actuator 540 moves the objective lens 520 in the optical axis direction,
The tracking actuator 550 is connected to the objective lens 52
0 is moved in the radial direction of the disk 500.

A detection signal from a photodetector (not shown) of the pickup 530 is supplied to a signal generation unit 580. The signal generation unit 580 generates an RF signal, a focus error signal FE, and a tracking error signal TE based on the detection signal.
Generate a signal such as.

The demodulation section 590 receives the RF signal from the signal generation section 580, and extracts and outputs the synchronization clock SYCLK and the synchronization data SYDATA based on the RF signal.

The focus servo control section 610 (focus equalizer) receives the focus error signal FE from the signal generation section 580 and controls the focus actuator drive section 620. Then, the focus actuator driving section 620 operates as the focus actuator 540.
Drive. As a result, the objective lens 520 moves in the optical axis direction so that focus is always achieved, and a minute spot of the laser beam is formed on the recording layer of the disk 500.

The tracking servo controller 630 (tracking equalizer) receives the tracking error signal TE from the signal generator 580 and controls the tracking actuator driver 640. Then, the tracking actuator driving section 640 drives the tracking actuator 550. Accordingly, the tracking state is always maintained, and the objective lens 520 is
, And the tracks on the recording layer of the disk 500 are tracked by the light beam.

The feed servo control section 650 (feed equalizer) receives the output (low frequency component) of the tracking servo control section 630 and receives a feed motor drive section 660.
Control. Then, the feed motor driving unit 660
Drives the feed motor 570 such that the feed motor 570 rotates intermittently.

The disk servo controller 670 (disk equalizer) receives the SYDATA from the demodulator 590 and controls the disk motor drive 680. Specifically, an interval (maximum inversion interval 14T) between reference signals included in SYDATA is measured, and CLV (Constant Linear Velocity) control is performed so that the interval becomes a predetermined value. Then, the disk motor driving unit 680 operates the disk motor 51.
Drive 0.

The motor rotation detection section 690 (motor rotation detection system) detects the level of the switching noise or the induced voltage superimposed on the induced voltage (signal from the drive terminal) generated at the drive terminal of the disk motor 510. The rotation state of the motor 510 is detected.

More specifically, when the CPU issues a disk rotation stop command and the disk motor drive unit 680 stops driving the disk motor 510 (the disk motor 51
Also, when 0 is in the non-driving state), an induced voltage (back electromotive force) is generated at the drive terminal of the disk motor 510 by the inertial rotation of the rotor (disk). The motor rotation detector 690 detects switching noise (noise generated by contact or non-contact between the commutator and the brush due to the inertial rotation of the rotor) superimposed on the induced voltage or the level of the induced voltage. Based on the detection result, the rotation stop of the disk motor 510 is determined. By doing so, even when a so-called brushed motor is used as the disk motor 510, it is possible to determine the rotation stop of the motor (disk) using the motor rotation detection unit 690 having a simple configuration.

A control section 600 having a CPU interface (I / F) exchanges data with a CPU (processor in a broad sense), and performs demodulation section 590, focus servo control section 610, and tracking servo control section 63.
0, various control signals are supplied to the feed servo control section 650, the disk servo control section 670, the motor rotation detection section 690, and the like.

The signal generator 580, demodulator 590, controller 600, and focus servo controller 61 shown in FIG.
0, focus actuator drive section 620, tracking servo control section 630, tracking actuator drive section 640, feed servo control section 650, feed motor drive section 660, disk servo control section 670, disk motor drive section 680, motor rotation detection section 690
The function of each block such as a (motor rotation detection system) may be realized by hardware such as a dedicated circuit or an ASIC, or may be realized by a combination of a processor such as a DSP or a CPU and software (firmware). .

2. Rotation detection based on switching noise In this embodiment, a brushed motor is used as the disk motor 510 in FIG. The use of a motor with a brush eliminates the need for an electronic rectifier circuit and a Hall element required for a brushless motor. Therefore, the structure of the disk device can be simplified and the cost can be reduced.

However, if a brushless motor is used, it is possible to detect whether or not the disk (rotor of the motor) has stopped based on the phase switching signal in the electronic rectifier circuit. However, such detection cannot be performed with a brush motor. . For this reason, if a brushed motor is used as the disk motor 510 in FIG. 1, the following problem may occur.

That is, when the user of the disk device presses the eject button of the disk, the CP
The disk rotation stop command from U is transmitted to the disk motor drive unit 680 via the control unit 600 and the disk servo control unit 670. Then, the disk motor driving unit 6
80 sets the output to the drive terminal of the disk motor 510 to 0
V or high impedance state (mute state)
To As a result, the disk motor 510 enters the non-drive state, and the rotation of the disk 500 starts to stop.

However, for example, in the case of a DVD or the like, the rotation speed of the disk is much higher than that of a CD. For example, 1x speed of DVD is equivalent to 8x speed of CD,
A quadruple speed of a DVD is equivalent to a 32x speed of a CD. Therefore,
Even if the disk motor 510 is in the non-drive state, the disk 500 continues to rotate due to inertia for a certain period of time.
Then, the disk 50 is kept rotating in this manner.
When 0 is taken out, the disk 500 and the disk tray collide with each other, causing abnormal noise, and causing a problem such as damage to the disk 500.

In this case, the disk servo controller 670
Is the maximum inversion interval 14T (maximum pit length) as described above.
Is measured and CLV (constant linear velocity) control is performed, so that it is possible to determine the stop of the disk 500 based on the measurement result.

However, in the case where servo control (PLL lock) has been lost due to a defect or fingerprint of the disk 500, the disk 500 is stopped in such a measurement of the maximum inversion interval. It cannot be determined with certainty. Therefore, it is impossible to solve the above-mentioned problems of generating abnormal noise and damaging the disk 500.

Further, for example, when the user turns off the power of the disk device and immediately turns on the power several seconds later, it has been found that the following problem occurs.

That is, when the power supply of the disk device is turned on, the laser is turned on as shown in FIG. 2 (step S1), and a focus search is performed (step S1).
3). Next, the focus error signal FE and the amount of reflected laser light are detected (step S4), and the type of the disc is determined based on the detection result (step S5).
For example, it is determined whether the DVD is a DVD or a CD, and whether the DVD is a single-layer DVD or a double-layer DVD. Then, based on the determination result, each disk (1
The process branches to processing corresponding to a layer type DVD, a double layer type DVD, a CD, etc. (step S6).

However, if the user immediately turns on the power after turning off the power of the disk device, the disk is still rotating and steps S3 and S3 in FIG.
4, the processing of S5 is performed, and there is a problem that the disc type is erroneously determined.

In order to solve the above problems, the present embodiment is provided with the motor rotation detecting section 690 (motor rotation detecting system) shown in FIG. The rotation of the disk is determined to be stopped by detecting switching noise superimposed on the induced voltage generated at the drive terminal of the disk motor 510 by the motor rotation detector 690.

Hereinafter, the detection principle of this embodiment will be described.

As shown in FIG. 3A, the motor with brush 10 has a commutator 12 (commutator) and brushes 14 and 16 connected to drive terminals 18 and 20 of the motor. Then, as shown in FIG.
Are connected to the coils 24, 26, 28 (in the case of three slots), and rotate in the magnetic field generated by the stators 30, 32.

The rotor structure of the motor with brush 10 may be any of an inner rotor type, an outer rotor type and a flat rotor type.

In such a motor 10 with a brush, as shown in FIG. 3C, an induced voltage is generated at the drive terminal 20 (or 18) even after the motor is in the non-drive state, and the induced voltage is generated. It has been found that switching noise is superimposed on the voltage.

That is, even after the motor 10 is in the non-drive state, the rotor keeps rotating by inertia for a given time. Then, an induced voltage (back electromotive force) is generated in the coils 24, 26, 28 by the magnetic field of the stators 30, 32, and an induced voltage is also generated in the drive terminal 20 (or 18) as shown in FIG. . The induced voltage gradually decreases as the rotation of the rotor slows down.

Further, switching noise is superimposed on the induced voltage generated at the drive terminal 20, as shown in FIG. The switching noise is generated by contact or non-contact between the electrodes of the commutator 12 and the brushes 14 and 16 due to the inertial rotation of the rotor. That is, the coils 24, 26, 28
The switching noise accompanying the switching between energization and non-energization is superimposed on the induced voltage of the drive terminal 20.

In this embodiment, by judging the existence of the switching noise, the determination of the stop of the rotation of the disk has succeeded.

FIG. 4 shows an example of the configuration of the motor rotation detector 690.

The detection section 40 is provided with a drive terminal 512 of the disk motor 510 (motor with brush) in the non-drive state.
The switching noise generated in the signal SMV (induction voltage) from the switch is detected. Then, based on the detection result (signal SMSIG), the determination unit 50 determines the disk motor 51
Zero rotation stop is determined.

More specifically, the detection section 40 includes a high-pass filter & level shift section 42, a hysteresis comparator section 44, a hysteresis width setting register 46, and a logic level shift section 48.

Here, the high-pass filter & level shift unit 42 performs a filtering process for passing a high frequency component of the signal SMV (induced voltage) and shifts the signal SMV to a level of a given reference voltage.

That is, the signal SMV from the drive terminal 512 of the disk motor 510 in the non-drive state is
(A) is schematically shown. As shown in FIG. 5B, the high-pass filter and level shift unit 42 allows only the high frequency component of the signal SMV to pass and shifts the signal SMV to the level of the reference voltage VREF.

By passing only the high-frequency components of the signal SMV, the low-frequency components that gradually lower the voltage level of the signal SMV in FIG. 5A can be cut. Also,
By shifting the signal SMV to the level of the reference voltage VREF, switching noise is generated on the positive electrode side or the negative electrode side with respect to VREF. By doing so, the accuracy of the comparison process between the noise level and the hysteresis width HYS performed in the hysteresis comparator unit 44 at the subsequent stage can be improved.

The hysteresis comparator 44 receives the signal SMN from the high-pass filter and level shifter 42.
The noise level is set based on the hysteresis width setting signal HS from the hysteresis width setting register 46 as shown in FIG.
A process of detecting noise exceeding the hysteresis width HYS of (B) as switching noise is performed.
The MHC is output to the logic level shift unit 48.

The hysteresis width setting register 46 stores a hysteresis width HYS in the hysteresis comparator 44.
Is a register for setting. The setting of the hysteresis width HYS in the hysteresis width setting register 46 is as follows.
CPU (firmware) via control unit 600 in FIG.
It is performed by

The logic level shift section 48 converts the detection signal SMHC from the hysteresis comparator section 44 to a logic level (for example, 0 to 5 V), and outputs the converted detection signal SMSSIG.

That is, as shown in FIG.
SIG changes to an H level (for example, 5 V) when switching noise occurs on the positive side with respect to the reference voltage VREF in FIG. 5B, and changes to an L level (for example, 0 V) when switching noise occurs on the negative side. ).

The detection signal SMSSIG is output to the outside through the monitor terminal 58. By monitoring the detection signal SMSSIG output from the monitor terminal 58, it is possible to easily determine whether the hysteresis width and the target time set in the hysteresis width setting register 46 and the target time setting register 54 are appropriate. You will be able to find out.

The determination unit 50 includes a count clock generation unit 5
2. It includes a target time setting register 54 and a timer unit 56.

The count clock generation section 52 generates a clock CLK used for the count operation in the timer section 56.

The target time setting register 54 includes a timer unit 5
6 is a register for setting a target time to be used. The setting of the target time in the target time setting register 54 is performed by the CPU (firmware) via the control unit 600 of FIG.

The timer section 56 receives a switching noise detection signal from the logic level shift section 48, a clock CLK from the count clock generation section 52, and a target time setting signal TS from the target time setting register 54. Then, as indicated by A1 in FIG. 5 (D), it is timed whether or not the target time TSTOP set by the signal TS has elapsed since the switching noise was not detected. Then, when the elapse of the target time TSTOP is counted, it is determined that the disk (rotor of the motor) has stopped, and FIG.
The signal SMREV is changed to the L level as indicated by A2.

More specifically, timer section 56 includes a counter (not shown), and this counter is reset at the edge (falling edge or rising edge) of signal SMSSIG. After the reset by the edge of the SMSIG, the counting operation is performed based on the clock CLK,
When the count value matches the count value corresponding to target time TSTOP, signal SMREV is changed to L level.

As described above, if it is determined that the rotation of the disk has stopped on the condition that the target time TSTOP has elapsed, a more accurate rotation stop determination can be realized.

That is, the pulse of the signal SMSIG in FIG. 5C is not always output without interruption, and the pulse may disappear depending on the contact state between the brush of the motor and the commutator. is there. For example, consider the case where the pulse indicated by A3 has disappeared in FIG. In such a case, if it is determined that the rotation of the disk has stopped at the time indicated by A1, an erroneous determination will be made. In particular, when the pulse as shown in A4 disappears, the situation becomes more serious.

On the other hand, in the present embodiment, the time TSTOP corresponding to several pulses elapses from the time indicated by A1.
At time 2, it is determined that the rotation of the disk has stopped. Therefore, even if the pulse disappears as indicated by A3 and A4, erroneous determination is not performed.

FIG. 6 shows a specific configuration example of the high-pass filter and level shift unit 42, the hysteresis comparator unit 44, and the logic level shift unit 48.

High-pass filter & level shift section 42
Includes a capacitor C1 having an SMV connected to one end and an SMN connected to the other end, and a resistor R1 having a VREF connected to one end and the SMN connected to the other end. These C1, R1
Constitutes a high-pass filter, and allows only the high frequency components of the signal SMV to pass. The resistance R
1 is connected to the reference voltage VREF,
As shown in (B), the signal SMN can be shifted to the level of the reference voltage VREF.

The hysteresis comparator 44 includes an operational amplifier 60 (operational amplifier) and resistors R2 and R3. The SMN is connected to the inverting input terminal (-) of the operational amplifier 60, and the other end of the resistor R2 whose one end is connected to VREF is connected to the non-inverting input terminal (+). And the resistor R3
Is connected to the other end (non-inverting input terminal) of the resistor R2, and the other end is connected to the output SMHC of the operational amplifier 60.

The resistance value of the resistor R3 can be variably set based on the signal HS from the hysteresis width setting register 46. Then, by changing the resistance value of R3 (the resistance value of R2 may be changed), the hysteresis width HYS of FIG. 5B can be changed.

The logic level shift section 48 is connected to VDD
(Logic voltage) is connected to one end and the SMHC is connected to the other end. The resistor R4 includes an inverter circuit 62 (for example, a buffer with a Schmitt function) that receives the SMHC and outputs the SMSIG. Thereby, signal SMHC can be converted to a logic level.

For example, when the logic level is 0 to VDD (V)
5B, the upper threshold value VTH1 and the lower threshold value VTH2 of the hysteresis shown in FIG. 5B are expressed by the following equations (1) and (2).

VTH1 = VDD × R2 / (R2 + R3) + VREF × R3 / (R2 + R3) (1) VTH2 = VREF × R3 / (R2 + R3) (2) Accordingly, the hysteresis width HSYS is represented by the following equation (3).

HYS = VTH1−VTH2 = VDD × R2 / (R2 + R3) (3) As is apparent from the above equation (3), the hysteresis width HYS can be variably controlled by changing the resistance value of R3.

FIGS. 7A to 7G show that the resistance value of R3 is changed to change the hysteresis width HYS (HYS = 0.45, 0.24, 0.12, 0.08). ,
0.06, 0.05, 0.04 V)
4 shows a waveform example of MSIG.

In this embodiment, as shown in FIGS. 4 and 6,
The signal SMSSIG is output to the outside (for example, outside of a semiconductor integrated device such as an IC) via the monitor terminal 58. Therefore, by performing an adjustment operation of monitoring the state of the signal SMSSIG while changing the hysteresis width HYS and the target time TSTOP, the hysteresis width setting register 4 is changed.
6 and the target time setting register 54 can be set to appropriate values.

For example, in FIGS. 7A and 7B, the SMSI
The G pulse is output at a frequency lower than the frequency of the switching noise, and the periodicity of the signal is not good. Further, in FIG. 7C, although the number of pulses output at the frequency of the switching noise is large, the number of lost pulses is also large as indicated by B1 to B5. Therefore,
7A, 7B, and 7C (R3 = 10, 2
0, 40 KΩ), it can be determined that the hysteresis width HYS is larger than an appropriate value.

On the other hand, in FIGS. 7 (D), (E) and (F),
The SMSIG pulse is output periodically at almost the same frequency as the switching noise. Therefore, the settings of FIGS. 7D, 7E, and 7F (R3 = 60, 80,
100KΩ), it can be determined that the hysteresis width HYS is almost an appropriate value.

In FIG. 7D, as indicated by B6,
Although some of the pulses of the switching noise frequency are intermittently lost, this loss is considered to have occurred accidentally due to the state of contact between the commutator of the motor and the brush, and the hysteresis width HYS has an appropriate value. Can be determined.

On the other hand, in FIG.
The G pulse is output at a frequency higher than the switching noise, and it is considered that noise different from the switching noise has been detected. Therefore, in the setting of FIG. 7G (R3 = 120 KΩ), the hysteresis width HYS
Is smaller than the appropriate value.

As described above, by performing the adjustment operation while monitoring the signal SMSIG output from the monitor terminal 58, the appropriate hysteresis width HYS can be easily set.

As shown by B6 in FIG. 7D, the contact state between the commutator of the motor and the brush, etc. causes
The pulse of the frequency of the switching noise may intermittently (accidentally) disappear. Also in such a case, the signal SMSSIG output from the monitor terminal 58 is monitored,
By setting the target time according to the pulse disappearance state in the target time setting register 54, an appropriate target time can be set. For example, if the number of intermittently disappearing pulses is in the range of 1 to N, the target time may be set to a time longer than the time of the number of pulses of N.

Note that the configurations of the detection unit 40 and the determination unit 50 are as follows.
The configuration is not limited to the configuration shown in FIG.

For example, the target time is fixed at a fixed value,
The SMREV may be changed to the L level without waiting for the target time to elapse.

Further, the detecting section 40 may be configured as shown in FIG.

In FIG. 8, the A / D converter 70 converts an analog signal SMV into a digital signal SMD. And
The digital comparator 72 performs digital comparison processing based on the digital signal SMD and the signal HS from the hysteresis width setting register 46, and outputs the detection signal SMSSIG as described with reference to FIG.

According to the configuration of FIG. 8, the A / D converter 70 is required, so that the circuit scale is increased. On the other hand, the comparison processing is performed by digital processing, so that the resolution of the comparator level can be increased. .

3. Rotation Detection Based on Induction Voltage Level In FIG. 4, rotation detection is performed based on switching noise. However, rotation detection may be performed based on the level of induction voltage (back electromotive force) generated at the drive terminal of the motor. . FIG. 9 shows a configuration example of the motor rotation detection unit 690 in this case.

FIG. 9 differs from FIG. 4 in the configuration of the detection unit 40, and the configuration of the determination unit 50 is the same as in FIG.

The detection section 40 shown in FIG. 9 detects the level of the induced voltage generated in the signal SMV from the drive terminal 512 of the disc motor 510 (motor with brush) in the non-drive state. Then, the determination unit 50 determines whether or not the rotation of the disk motor 510 is stopped based on the detection result (signal SMSIG).

More specifically, the detection section 40 includes a low-pass filter section 82, a comparator section 84, and a logic level shift section 88.

Here, the low-pass filter section 82 performs a filtering process for passing a low frequency component of the signal SMV (induced voltage).

That is, the signal SMV from the drive terminal 512 of the disk motor 510 in the non-drive state is
(A) is schematically shown. As shown in FIG. 10B, the low-pass filter unit 82
Only low frequency components of the MV are passed.

By passing only the low frequency components of the signal SMV, the switching noise generated in FIG. 10A can be removed. By doing so, the accuracy of the comparison process performed by the comparator unit 84 at the subsequent stage can be improved.

The comparator section 84 determines the voltage level of the signal SMB from the low-pass filter section 82 and the threshold voltage V
And outputs a detection signal SMC to the logic level shift unit 88.

The logic level shift section 88 converts the detection signal SMC from the comparator section 84 to a logic level (for example, 0 to 5 V), and converts the converted detection signal SMSSIG.
Is output.

That is, as shown in FIG.
MSIG changes to L level (for example, 0 V) when the signal SMB becomes smaller than the threshold voltage VS.

Then, the judgment unit 50 determines whether or not C1 in FIG.
As shown in (1), it is determined whether or not the target time TSTOP set by the signal TS has elapsed since the detection signal SMSSIG changed to the L level. Then, when the elapse of the target time TSTOP is counted, it is determined that the disk has stopped, and the signal SMREV is changed to the L level as indicated by C2 in FIG. 10D. Thus, the target time TSTO
If it is determined that the rotation of the disk has stopped on the condition of the passage of P, more accurate rotation stop determination can be realized.

According to the configuration of FIG. 9, there is an advantage that the circuit configuration can be simplified as compared with FIG.

However, the configuration of FIG. 9 has a disadvantage that an analog circuit for generating an analog threshold voltage VS is required.

Further, even if the low-pass filter section 82 is provided, noise such as switching noise cannot be completely removed, so that there is a disadvantage that the accuracy of the rotation stop determination is reduced.

For example, FIG. 11 shows an actual measurement example of the waveform of the signal SMV. As shown in FIG. 11, the voltage level of the SMV changes gradually and the change width of the voltage level is small. The noise level is much larger than the change width of these voltage levels. Therefore, in the configuration of FIG. 9, it is very difficult to set the threshold voltage VS, and the accuracy of the rotation stop determination is reduced.

On the other hand, according to the configuration of FIG.
, The voltage level of the signal SMV changes smoothly,
Even when the noise level is large, as described with reference to FIGS. 7A to 7G, it is possible to realize the rotation stop determination with high accuracy.
In addition, in the configuration of FIG. 4, the main variation factor in determining an appropriate hysteresis width is only the number of turns of the motor coil and the like. Therefore, according to the configuration of FIG. 4, there is an advantage that the adjustment operation can be facilitated.

FIG. 12 shows the configuration of the low-pass filter unit 8 shown in FIG.
2, a specific configuration example of the comparator section 84 and the level shift section 88 will be described.

The low-pass filter section 82 includes a resistor R11 having an SMV connected to one end and an SMB connected to the other end;
REF includes a capacitor C11 connected to one end and SMB connected to the other end. These R11 and C11 form a low-pass filter.

The comparator section 84 includes an operational amplifier 100
(Operational amplifier) and a resistor R12. Operational amplifier 100
Is connected to the inverting input terminal (−) of the resistor R12, and the non-inverting input terminal (+) is connected to a resistor R12 having one end connected to VS.
Are connected to each other.

The logic level shift section 88 is connected to VDD
(Logic voltage) is connected to one end and the SMC is connected to the other end. A resistor R13 and an inverter circuit 102 (for example, a buffer with a Schmitt function) that receives the SMC and outputs the SMSSIG. Thus, the level of the signal SMC can be converted to a logic level.

According to the configuration of the present embodiment described above (FIGS. 4 and 9), a brush motor can be used as the disk motor 510 for rotating the disk 500 of FIG. Simplification and cost reduction.

Even when the disk servo controller 670 or the like in FIG. 1 cannot detect the stop of the rotation of the disk 500, based on the determination result of the motor rotation detector 690,
The stop of the rotation of the disk 500 can be detected. Therefore, problems such as generation of abnormal noise when the disk 500 is taken out and damage of the disk 500 can be solved.

For example, in FIG. 2 described above, when the user turns on the power immediately after turning off the power of the disk device, the steps S3 and S4 in FIG. , S5 is performed, and the type of the disc 500 is incorrectly generated.

On the other hand, in the present embodiment, as shown in step S2 of FIG. 13, prior to the discrimination process of the type of the disc 500, the stop of the disc rotation is detected based on the result of the determination by the motor rotation detector 690. it can. Therefore,
The above problem that the type of the disc 500 is erroneously set can be effectively solved.

Note that the present invention is not limited to this embodiment,
Various modifications can be made within the scope of the present invention.

For example, it is particularly preferable that the motor rotation detection system of the present invention is applied to a disk device, but can be applied to various other electronic devices.

The motor to be subjected to rotation detection according to the present invention may be any type of motor that generates switching noise at least due to contact or non-contact between the commutator and the brush. It is not limited to the motor having the structure described in B).

Also, the configuration of the motor rotation detection system is as follows.
The configuration described with reference to FIGS. 4, 6, 8, 9, and 12 is particularly desirable, but is not limited thereto, and various modifications can be made.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a configuration example of a disk device.

FIG. 2 is a flowchart illustrating a disc type determination process performed after the power is turned on.

FIGS. 3A, 3B, and 3C are diagrams for explaining a motor with a brush;

FIG. 4 is a functional block diagram illustrating a configuration example of a motor rotation detection unit.

FIGS. 5A, 5B, 5C, and 5D are diagrams schematically illustrating waveform examples of various signals in a motor rotation detection unit.

FIG. 6 is a diagram illustrating a configuration example of a high-pass filter and level shift unit, a hysteresis comparator unit, and a logic level shift unit.

FIGS. 7A to 7G are diagrams for explaining a method of adjusting a motor rotation detection unit.

FIG. 8 is a functional block diagram illustrating a configuration example of a motor rotation detection unit.

FIG. 9 is a functional block diagram illustrating a configuration example of a motor rotation detection unit.

FIG. 10A, FIG. 10B, FIG. 10C, FIG.
It is a figure which shows typically the example of a waveform of various signals in a motor rotation detection part.

FIG. 11 is an actual measurement example of an SMV signal waveform.

FIG. 12 is a diagram illustrating a configuration example of a low-pass filter unit, a comparator unit, and a logic level shift unit.

FIG. 13 is a flowchart illustrating a disc type discrimination process when the method of the present embodiment is used.

[Explanation of symbols]

 Reference Signs List 40 detection unit 42 high-pass filter & level shift unit 44 hysteresis comparator unit 46 hysteresis width setting register 48 logic level shift unit 50 determination unit 52 count clock generation unit 54 target time setting register 56 timer unit 58 monitor terminal 60 operational amplifier 62 inverter circuit 70A / D conversion unit 72 Digital comparator unit 82 Low-pass filter unit 84 Comparator unit 88 Logic level shift unit 100 Operational amplifier 102 Inverter circuit 500 Disk 510 Disk motor 520 Objective lens 530 Pickup 540 Focus actuator 550 Tracking actuator 560 Carriage 570 Feed motor 580 Signal generation unit 590 Demodulation unit 600 Control unit 610 Focus servo control Unit 620 Focus actuator drive unit 630 Tracking servo control unit 640 Tracking actuator drive unit 650 Feed servo control unit 660 Feed motor drive unit 670 Disk servo control unit 680 Disk motor drive unit 690 Motor rotation detection unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference)

Claims (14)

[Claims] 1. A system for detecting rotation of a motor, the switching noise being superimposed on an induced voltage generated at a drive terminal of the motor due to an inertial rotation of the rotor of the motor in a non-driving state, the switching noise comprising: Detecting means for detecting switching noise generated due to contact or non-contact between the commutator and the brush due to inertial rotation; and determining whether or not rotation of the motor rotor has stopped based on the detection result of the switching noise. A motor rotation detection system, comprising: a determination unit. 2. The method according to claim 1, wherein the detecting means performs a filtering process for passing a high frequency component of a signal from a driving terminal of the motor, and detects switching noise superimposed on the filtered signal. A motor rotation detection system. 3. The method according to claim 1, wherein the detecting unit shifts a level of a signal from a drive terminal of the motor to a given voltage level, and detects switching noise superimposed on the signal after the level shift. A motor rotation detection system, characterized in that: 4. The motor rotation detection system according to claim 1, wherein the detection unit detects noise whose noise level exceeds a given hysteresis width as the switching noise. 5. The method according to claim 4, further comprising: a hysteresis width setting unit for setting the hysteresis width; and a monitor terminal for outputting a detection result of the detection unit as a switching noise detection signal. Characteristic motor rotation detection system. 6. The method according to claim 1, wherein the determination unit determines that the rotation of the motor rotor has stopped after a given target time has elapsed since the switching noise was not detected. A motor rotation detection system. 7. The method according to claim 6, comprising: a target time setting means for setting the target time; and a monitor terminal which outputs a detection result of the detection means as a switching noise detection signal. Characteristic motor rotation detection system. 8. A system for detecting rotation of a motor, comprising: detection means for detecting a level of an induced voltage generated at a drive terminal of the motor due to inertial rotation of a rotor of the motor in a non-driven state; And a determining means for determining whether or not the rotation of the rotor of the motor has stopped based on the detection result of the level of the motor. 9. The method according to claim 8, wherein the determination unit determines that the rotation of the rotor of the motor has stopped after a given target time has elapsed since the level of the induced voltage became a given voltage level. A motor rotation detection system. 10. A disk drive including the motor rotation detection system according to claim 1, wherein the rotation of the disk is controlled based on a signal from a pickup that is servo-controlled to follow a track of the disk. And a motor driving means for driving the motor under the control of the disk servo control means. 11. The disk rotation control device according to claim 10, wherein even when the disk servo control unit does not detect the rotation stop of the disk, the rotation stop of the disk is detected based on the determination result of the motor rotation detection system. A disk device characterized by the above-mentioned. 12. The disk device according to claim 10, wherein, prior to the disk type determination processing, the disk rotation stop is detected based on a determination result in the motor rotation detection system. 13. The adjustment method used in the motor rotation detection system according to claim 5, wherein a pulse of a switching noise detection signal output from the monitor terminal is periodically output at a frequency of the switching noise. Setting the hysteresis width of the hysteresis width in the hysteresis width setting means. 14. An adjustment method used in the motor rotation detection system according to claim 7, wherein a pulse of a frequency of the switching noise intermittently disappears among pulses of the detection signal of the switching noise output from the monitor terminal. In this case, a target time according to the pulse disappearance state is set in the target time setting means.