JP2003153569A - Motor control circuit and disk playback system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control circuit and a disk playback system, where a tracking control technique which implements fine tracking control and power saving is incorporated. SOLUTION: The disk playback system comprises a tracking error signal generating circuit 4, which generates tracking error signals based on an photon detection signal from an optical pickup 2; a thread motor 3, which moves the optical pickup 2 to a specified track on a disk 1; a digital servo processing circuit 152, which converts either of the tracking error signal and a signal corresponding to the tracking error signal into a target signal, corresponding to the amount of the movement of the thread motor 3; and a PWM generation circuit 57 which generates a PWM drive control signal subjected to pulse width modulation in a low-frequency band, based on the target signal. The thread motor is driven directly by the PWM drive signal in the low-frequency band, which is generated based on the PWM drive control signal in the low-frequency band. The low frequency band is within a range from several tens to several hundreds of Hz.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control circuit and a disc reproducing apparatus, and more particularly, to a motor control circuit capable of controlling the motor at a low speed to drive the motor smoothly and greatly improving the power efficiency of the motor. Disc playback device

[0002]

2. Description of the Related Art A disk reproducing apparatus is one of the motor control circuits required to drive a motor at low speed and smoothly. In the following description of the conventional technique, the conventional technique relating to motor rotation control will be described by taking the case of the disk reproducing device as an example. When the tracking control for aligning the optical pickup with the position of the track on the disk surface formed in a spiral shape is repeated, the position of the objective lens mounted on the optical pickup is set to a predetermined track on the disk surface. Gradually shift from position. With an increase in the shift amount of the objective lens from a predetermined track, the shape of the light spot formed on the disk surface is not a perfect circle shape but an elliptical shape. As a result, tracking control and reading of the signal recorded on the disk will also be inconvenient.

Further, in the case of magneto-optical recording, when the shift amount of the objective lens from a predetermined track becomes large,
The positional deviation between the laser spot and the magnetic head becomes large, and the size of the magnetic head must be increased to obtain the strength (amount) of the magnetic field required for recording. Therefore, the current consumption must be made to flow, resulting in an increase in power consumption.

Therefore, while the shift amount of the objective lens from the predetermined track is not too large, the sled motor for moving the optical pickup is driven, and the sled motor is driven to shift the objective lens from the predetermined track. It is necessary to move the optical pickup to a position where the amount becomes zero and align the objective lens with a predetermined track. Further, the tracking error signal is superimposed on the tracking error signal as an offset signal as the shift amount of the objective lens from the predetermined track increases. The tracking error signal is applied to the sled motor as a motor drive signal.

Incidentally, the sled motor cannot be rotationally started unless a voltage higher than the starting voltage is applied, but the starting voltage value is substantially equivalent to a voltage value that overcomes cogging. Here, the cogging is caused by the shape of the permanent magnet type rotating machine, and is a holding torque generated when the rotor is rotated at a low speed. For example, when the shaft of the DC motor is slowly rotated by hand, a slight vibration is transmitted to the hand, which causes a “shaking”.

When the shift amount of the objective lens from a predetermined track reaches a shift amount required to generate a voltage higher than the starting voltage of the sled motor in order to move the optical pickup, the sled motor is rotationally started. As a result, the motor rotates by the amount of overcoming the amplitude due to the cogging. This rotation amount corresponds to the amount of alignment of the objective lens with the predetermined track until the shift amount of the objective lens from the predetermined track becomes substantially zero.

After that, by further tracking control, the shift amount of the objective lens from a predetermined track becomes a shift amount required to generate a voltage higher than the starting voltage of the sled motor in order to move the optical pickup again. When it reaches, the sled motor moves the optical pickup again until the shift amount of the objective lens from the predetermined track becomes approximately zero.

However, according to such a method,
When performing tracking control, the sled motor is not activated until the shift amount from the predetermined track of the objective lens overcomes the cogging amplitude amount, so the shift amount is within the cogging amplitude amount. In the state of being set to, the positional adjustment of moving the optical pickup until the shift amount from the predetermined track reaches the position of zero cannot be performed in small increments. Then, the shift amount from the predetermined track of the objective lens becomes large enough to overcome the cogging amplitude amount, and the rotation of the sled motor starts the movement of the optical pickup. The motor and the optical pickup will make a jerky movement.

FIG. 5 is a schematic diagram for explaining such an operation, and is a schematic diagram showing an example of the rotating operation of the sled motor for moving the position of the optical pickup. That is, FIG. 5 shows the operation in the case where the motor drive control system does not include a sub control loop for smoothing the rotation operation of the sled motor.

In such a case, as shown in FIG. 5, the motor drive voltage applied to the sled motor reaches the starting voltage, the sled motor is rotationally started, and the position of the optical pickup is set to the cogging amplitude. After moving to the amount to overcome, temporarily set the applied voltage to the sled motor to 0V.
It is reduced to the vicinity and the rotation of the sled motor is stopped. Then, again, as the shift amount of the objective lens from the predetermined track by the tracking control increases, the motor drive voltage gradually increases to the starting voltage of the sled motor in proportion to the increase of the shift amount. When the motor drive voltage reaches the starting voltage,
The sled motor is rotationally activated to move the position of the optical pickup to an amount that overcomes the cogging amplitude, and then the voltage applied to the sled motor is again reduced to around 0 V to stop the rotation of the sled motor. By repeating this operation, the sled motor rotates and
The stopped state is repeated, and along with that, the optical pickup also repeatedly moves and stops, resulting in a jerky movement.

Here, in order to smoothly move the optical pickup and reduce the shift amount of the objective lens from a predetermined track, in the prior art, a sled motor having two control loops, a main control loop and a sub control loop. It is envisaged that drive control means will be provided. FIG. 4 shows a main control loop and a sub control loop.
It is a block diagram for explaining a sled motor drive control means having one control loop.

Incidentally, FIG. 4 shows an objective lens provided in the optical pickup for converging a laser beam from the optical pickup to a track on the disk surface.
An actuator serving as an objective lens moving means for moving the objective lens in the radial direction of the disc, and further, operating the objective lens moving means according to a tracking error signal to cause the objective lens to follow a track of the disc. The tracking servo means for that is omitted.

In FIG. 4, 1 is a disc on which various data are recorded, 2 is an optical pickup for irradiating the surface of the disc 1 with a laser beam, and 3 is a sled motor for moving the optical pickup 2 in the radial direction of the disc 1. , 4 are tracking error signal generation circuits for generating a tracking error signal indicating the amount of deviation of the optical pickup 2 from a predetermined track of the disk 1 based on a light detection signal output from the optical pickup 2, 5 ″ is a thread motor 3 To drive the pulse width duty cycle (ie,
PWM (Pul) in which pulse width modulation is performed by changing the pulse width ratio of the H level side pulse and the L level side pulse)
se Width Modulation) A drive control circuit for generating a drive control signal, 6'is a PWM driver for generating a PWM drive signal for driving the sled motor 3 based on the PWM drive control signal generated by the drive control circuit 5 ". , 7 are low-pass filters for integrating the PWM drive signal generated by the PWM driver.

Further, 8 is a Hall element for converting a change in magnetic flux density indicating the rotation speed of the sled motor 3 into an electric signal and detecting it as a sled motor speed signal, and 9 is a Hall element.
An amplifier 2 for amplifying the sled motor speed signal detected by the hall element 8.

The drive control circuit 5 "includes an AD converter 51, a digital servo processing circuit 152, a speed signal generating circuit 53, a comparator 54, and a digital servo processing circuit 2.
55, amplifier 156, and PWM generation circuit 57 '
Is provided.

The AD converter 51 is an AD converter for converting the tracking error signal generated by the tracking error signal generation circuit 4 and the sled motor speed signal amplified by the amplifier 29 into digital signals. Yes, digital servo processing circuit 1
Reference numeral 52 denotes a sled motor servo means for converting a tracking error signal converted into a digital signal or a signal corresponding to the tracking error signal into a target signal corresponding to the movement amount of the sled motor. The speed signal generation circuit 53 detects the rotation speed of the sled motor and converts it into a digital signal based on the sled motor speed signal.
This is a circuit for generating a speed signal which is a rotation inhibition signal of the sled motor 3.

The comparator 54 is a difference signal generating means for generating a difference signal by subtracting the speed signal generated by the speed signal generation circuit 53 from the target signal generated by the digital servo processing circuit 152. The digital servo processing circuit 255 is a processing circuit for generating a servo amount (that is, an error signal) for driving the sled motor 3 based on the difference signal generated by the comparator 54, and the amplifier 1 56 Is for amplifying the servo amount, and the PWM generation circuit 57 'is a PWM drive control signal pulse-width modulated to drive the sled motor 3 on the basis of the amplified servo signal. Is generated.

As shown in FIG. 4, in the prior art,
The optical detection signal detected by the optical pickup 2 is input to a tracking error signal generation circuit 4 to generate a tracking error signal for moving the optical pickup 2 to a predetermined track position on the surface of the disk 1, and the tracking error signal is generated. The error signal is sent by the AD converter 51.
Converted to digital signal, digital servo processing circuit 1
52 is input.

After converting either the tracking error signal or the signal corresponding to the tracking error signal into a target signal corresponding to the movement amount of the sled motor 3 in the digital servo processing circuit 152. The difference signal from the speed signal is input to the digital servo processing circuit 255 through the comparator 54, and the servo amount for driving the sled motor 3 is calculated.

The servo amount is amplified by the amplifier 156, and the PWM generation circuit 57 'generates a pulse width-modulated PWM drive control signal for driving the sled motor 3. The control signal is generated as a pulse width modulated PWM signal in a relatively high frequency band (several tens kHz to several hundreds kHz) in order to improve the efficiency of the motor driver. The generated PWM drive control signal is converted into a PWM drive signal for driving the sled motor 3 by the PWM driver 6 ′,
Further, the PWM drive signal is integrated through the low-pass filter 7 to be a motor drive signal of the integrated analog signal, and the sled motor 3 is driven. The above-described motor drive signal generation loop serves as the main control loop.

On the other hand, the output signal from the Hall element 8 (that is, the sled motor speed signal) for detecting the change of the magnetic flux density with the rotation speed of the sled motor 3 as the sled motor speed signal is amplified by the amplifier 29. , A
It is input to the D converter 51 and converted into a digital signal. The converted digital signal is used as the speed signal generation circuit 53.
Is generated as a speed signal and input to the comparator 54.

The speed signal input to the comparator 54,
The target signal is compared and collated, and the difference signal obtained by subtracting the speed signal from the target signal is generated and input to the digital servo processing circuit 255, and the servo amount for driving the sled motor 3 is calculated. To be done. The servo amount is amplified by the amplifier 156, and the PWM generation circuit 5
7'generates the PWM drive control signal. The generated PWM drive control signal is converted into the PWM drive signal for driving the sled motor 3 by the PWM driver 6 ′, and further, the PWM drive signal is integrated via the low pass filter 7, The sled motor 3 is driven by a motor driving signal of an integrated analog signal. The above motor drive signal generation loop serves as a sub-control loop. That is, in the prior art, tracking control is performed using two control loops, the main control loop and the sub control loop.

As shown in FIG. 5, unlike the case where the sub-control loop is not provided, in the case of applying the conventional method having the sub-control loop as shown in FIG. 4, the objective lens is moved by the tracking control. When the sled motor 3 is activated to shift the position of the optical pickup 2 by shifting from a predetermined track position, the sub control loop detects the rotation speed of the sled motor 3 at that moment through the hall element 8. Then, the comparator 54 controls to reduce the voltage applied to the sled motor 3 by setting it as a difference signal from the target signal so that the rotation speed of the sled motor 3 becomes zero.

On the other hand, in the main control loop,
Even if there is a slight shift amount from the predetermined track position of the objective lens, the servo gain is set so high that the sled motor 3 is activated. At the next moment when is stopped, a slight shift amount from the predetermined track position of the objective lens by tracking control causes
The sled motor 3 is activated, and the sled motor 3 is activated. On the other hand, when the sled motor 3 is activated, the sled motor 3 is controlled to be stopped immediately by the sub control loop as described above.

By repeating the above operation, it is possible to perform tracking control with a very small shift amount of the objective lens from the predetermined track position. Thus, when the tracking control using the sub control loop and the main control loop is performed, the sled motor 3 is used as shown in FIG. 6 instead of the jerky movement as in the case of FIG. Will continue to rotate slowly and smoothly.

FIG. 6 is a schematic diagram showing an example of the rotating operation of the sled motor 3 for moving the position of the optical pickup 2 when the tracking control using the sub control loop and the main control loop is used. Is.
That is, as shown in FIG. 6, unlike the case of FIG. 5 in which the sub-control loop is not used, the sled motor 3 does not have the jerky motion of repeatedly rotating and stopping, and the sled motor 3 is surely However, the motor drive voltage applied to the sled motor 3 always moves back and forth around the start voltage of the sled motor 3.

The output means to the sled motor 3 is, as described above, in order to reduce the power loss in the motor driver, depending on the drive voltage of the sled motor 3, the PWM generation circuit 57 '. Thus, it is converted into a PWM drive control signal which is pulse width modulated in a relatively high frequency band (several tens kHz to several hundreds kHz), and is input to the PWM driver 6 '. The converted PWM drive control signal is converted into a PWM drive signal of the relatively high frequency band for driving the sled motor 3 by the PWM driver 6 ', and further, the PWM drive signal is integrated in the low pass filter 7. , Is an analog voltage, and is always applied to the sled motor 3.

[0028]

However, in the control using the above-mentioned sub-control loop, in order to realize the fine tracking control in which the shift amount of the objective lens from the predetermined track position is extremely small, As shown in FIG. 6, although the rotation speed of the sled motor is extremely low, it is basically constantly rotating, and the voltage applied to the sled motor is always in the vicinity of the starting voltage of the sled motor. This results in a transition, resulting in an increase in power consumption in the sled motor drive circuit.

Further, when the sled motor is controlled only by the main control loop without using the sub control loop, the amount of shift from the predetermined track position of the objective lens is large, but as shown in FIG. After the voltage applied to the motor reaches the starting voltage of the sled motor and the sled motor is started, the voltage once decreases to around 0 V, and further the tracking lens control shifts the objective lens from a predetermined track position. The driving voltage gradually increases to the starting voltage of the sled motor,
Control is performed to drive the sled motor again.

Therefore, compared with the control using the sub-control loop as shown in FIG. 6, the power consumption of the sled motor can be kept low, but the sled motor operation becomes jerky as described above and fine tracking is performed. Control cannot be realized. Therefore, the development of a tracking control technique having both fine tracking control and power saving has been a problem.

The present invention has been made in view of the above circumstances, and realizes a motor control circuit having a tracking control technique having both fine tracking control and power saving, and a disk reproducing apparatus using the motor control circuit. To be

[0032]

A first technical means is to apply a drive signal of a motor starting voltage or a voltage slightly higher than the starting voltage to the monitor to drive the motor at a low rotation speed. In a motor control circuit equipped with
By using a PWM drive signal that is pulse width modulated in a low frequency band as the drive signal, the drive circuit is immediately turned on when the drive circuit receives a signal for driving the motor. While keeping it in a state,
When a signal to stop driving the motor is received, the motor control circuit controls the drive circuit as close to the OFF state as possible.

A second technical means is the motor control circuit according to claim 1, wherein a frequency band of the PWM drive signal of the low frequency band used as the drive signal is within a range of several tens Hz to several hundreds Hz. The motor control circuit in FIG.

The third technical means is a tracking error signal generating means for generating a tracking error signal indicating the amount of deviation of the optical pickup from a predetermined track on the disk surface based on the optical detection signal output from the optical pickup. And a sled motor for moving the optical pickup onto the predetermined track on the disk surface,
Sled motor servo means for converting either the tracking error signal given from the tracking error signal generation means or a signal corresponding to the tracking error signal into a target signal corresponding to the movement amount of the sled motor. And a PWM signal generation means for generating a PWM drive control signal which is pulse width modulated in a low frequency band based on the target signal. The disk reproducing apparatus drives the sled motor directly by the PWM drive signal having the low frequency band generated based on the PWM drive control signal having the low frequency band.

A fourth technical means is a tracking error signal generating means for generating a tracking error signal indicating a deviation amount of the optical pickup from a predetermined track on the disk surface, based on a light detection signal outputted from the optical pickup. And a sled motor for moving the optical pickup onto the predetermined track on the disk surface,
Sled motor servo means for converting either the tracking error signal given from the tracking error signal generation means or a signal corresponding to the tracking error signal into a target signal corresponding to the movement amount of the sled motor. A speed signal generating means for detecting a rotation speed of the sled motor and generating a speed signal corresponding to the rotation speed; and a difference signal generating means for generating a difference signal obtained by subtracting the speed signal from the target signal, A PW that generates a PWM drive control signal that is pulse width modulated in a low frequency band based on the difference signal
In a disc reproducing apparatus including M signal generating means, a PWM drive signal composed of the low frequency band is generated based on the PWM drive control signal of the low frequency band obtained by the PWM signal generating means. The disk reproducing device directly drives the sled motor.

A fifth technical means is, in the disk reproducing apparatus according to claim 3 or 4, the low level generated based on the PWM drive control signal in the low frequency band generated by the PWM signal generating means. The present invention is characterized in that the frequency band of the PWM drive signal composed of the frequency band is in the range of several tens Hz to several hundreds of Hz in the disk reproducing device.

Thus, in the motor control circuit and the disk reproducing apparatus using the motor control circuit according to the present invention, the ineffective power applied to the sled motor is significantly reduced, and the power consumption of the sled motor is reduced. Can be greatly reduced, and fine tracking control with a very small shift amount of the objective lens from the predetermined track position can be performed.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION An example of an embodiment of a motor control circuit and a disc reproducing apparatus using the motor control circuit according to the present invention will be described below with reference to the drawings.
As a device to which a motor control circuit that is required to smoothly drive a motor at a low speed is applied, there is, for example, a disc reproducing device, as shown in the above-mentioned related art.

In the following description of the embodiment of the motor control circuit according to the present invention, the drive control of the sled motor in the case of the disk reproducing apparatus will be described as an example, but the motor according to the present invention will be described. The control circuit
The present invention is not limited to such a case, and should be applied to any device that needs to smoothly drive a motor at a low rotation speed, such as an optical recording / reproducing device or a magneto-optical recording / reproducing device. Is possible.

FIG. 1 is a block diagram showing an example of an embodiment of a disk reproducing apparatus using a motor control circuit according to the present invention.

Incidentally, in FIG. 1, an objective lens provided in the optical pickup for converging a laser beam from the optical pickup to a track on the disk surface,
An actuator serving as an objective lens moving means for moving the objective lens in the radial direction of the disc, and further, operating the objective lens moving means according to a tracking error signal to cause the objective lens to follow a track of the disc. The tracking servo means for that is omitted. Further, in FIG. 1, the same reference numerals are used for the same circuit parts as those of FIG. 4 shown as the prior art.

In FIG. 1, 1 is a disc for recording various data, 2 is an optical pickup for irradiating the surface of the disc 1 with a laser beam, and 3 is a thread motor for moving the optical pickup 2 in the radial direction of the disc 1. , 4 is a tracking error signal generation circuit for generating a tracking error signal indicating the amount of deviation of the optical pickup 2 from a predetermined track position of the disk 1 based on a light detection signal output from the optical pickup, and 5'is a thread motor. In order to drive No. 3, the pulse width modulated PWM (Pu) in which the duty cycle of the pulse width (that is, the ratio of the pulse width of the H level side pulse and the L level side pulse) is changed is applied.
drive control circuit for generating a drive control signal, 6 is a PWM driver for generating a PWM drive signal for driving the sled motor 3 based on the PWM drive control signal generated by the drive control circuit 5 ′. is there.

Further, the drive control circuit 5'is provided with an AD converter 51, a digital servo processing circuit 152 ', an amplifier 156, and a PWM generating circuit 57.

Here, the AD converter 51 is an AD converter for converting the tracking error signal generated by the tracking error signal generation circuit 4 into a digital signal, and the digital servo processing circuit 152 'converts it into a digital signal. A servo for driving the sled motor 3 by converting either the converted tracking error signal or the signal corresponding to the tracking error signal into a target signal corresponding to the movement amount of the sled motor 3. Is a processing circuit that provides a sled motor servo means for generating a quantity (ie, an error signal), an amplifier 156 is for amplifying the servo quantity, and a PWM generation circuit 57 is for amplifying the servo quantity. In order to drive the sled motor 3 to rotate based on the servo signal,
The pulse width modulated PWM drive control signal is generated.

In the tracking control of the disk reproducing apparatus shown in FIG. 1, the optical pickup 2 for irradiating the surface of the disk 1 with the laser beam is equipped with a photodetector for detecting the reflected light from the surface of the disk 1. Has been. The photodetection signal detected by the photodetector in the optical pickup 2 is input to the tracking error signal generation circuit 4 as in the case of the conventional technique shown in FIG. A tracking error signal for moving the optical pickup 2 is generated, and the tracking error signal is converted into a digital signal by the AD converter 51, and the digital servo processing circuit 15
2'is entered.

In the digital servo processing circuit 152 ',
After converting either the tracking error signal or the signal corresponding to the tracking error signal into a target signal corresponding to the movement amount of the sled motor 3,
A servo amount (that is, an error signal) for driving the sled motor 3 is calculated based on the target signal.

The servo amount is amplified by the amplifier 156 and pulse width modulated by the PWM generating circuit 57.
It is converted into a WM drive control signal. Here, the PWM drive control signal converted by the PWM generation circuit 57 is different from the case of the conventional technique in that it has an amplitude and a low frequency band (several tens of Hz to several tens Hz) necessary and sufficient for activating the sled motor 3. PWM with pulse width modulation consisting of
It is a signal.

The PWM drive control signal in the low frequency band generated by the PWM generation circuit 57 is used by the PWM driver 6 as a PWM drive signal in the low frequency band for driving the sled motor 3. Then, unlike the conventional technique shown in FIG.
The drive signal is directly applied to the sled motor 3 as a pulse-width-modulated pulse-shaped motor drive signal, and the sled motor 3 is controlled. The above motor drive signal generation loop serves as a tracking control loop.

That is, as described above, in the conventional technique, in order to improve the efficiency of the motor driver, the PWM drive signal PWM-modulated in a relatively high frequency band (ie, several tens kHz to several hundreds kHz) is used. The voltage applied to the sled motor 3 is integrated by a low-pass filter to form an analog voltage waveform. However, in the tracking control of FIG. A PWM drive control signal in a necessary and sufficiently low frequency band (for example, several tens Hz to several hundreds Hz) is generated by the PWM generation circuit 57, and based on the PWM drive control signal, the PWM drive control signal is output via the PWM driver 6. The PWM drive signal remains in the low frequency band, and is directly applied to the sled motor 3 as a pulsed drive voltage. There.

When the sled motor 3 is directly driven by the PWM drive signal in the low frequency band, as shown in FIG. 2, the sled motor 3 is only in the section at the H level of the PWM drive signal. A necessary and sufficient voltage is applied to drive the sled motor 3, and the sled motor 3 is activated. FIG. 2 is a schematic diagram showing an example of the rotation operation of the sled motor 3 in the motor control circuit according to the present invention shown in FIG.

That is, in the motor control circuit having the motor drive circuit as shown in FIG. 1 (that is, the PWM driver 6 shown in FIG. 1), as shown in FIG. 2, it is equal to the starting voltage of the sled motor 3. Alternatively, the pulse amplitude value has a voltage value slightly higher than the starting voltage (that is, the H-level voltage value shown in FIG. 2), and a low frequency band (for example,
P with pulse width modulation applied at several tens Hz to several hundreds Hz
When the WM drive signal is directly applied to the sled motor 3,
In response to the rise of the PWM drive signal to the H level,
The sled motor 3 is immediately activated to start the rotation operation at a low rotation speed (shown by the solid line in FIG. 2).
On the other hand, when the PWM drive signal is in the L level section,
Although the voltage applied to the sled motor 3 is zero, the sled motor 3 continues to rotate without stopping immediately due to inertia so far (indicated by a broken line in FIG. 2). Again, the next H level section of the PWM drive signal is encountered, and the drive voltage of the sled motor 3 is applied.

By repeating such operations, the sled motor 3 continues to rotate smoothly at a low speed without stopping. That is, in the motor control circuit including the motor drive circuit (that is, the PWM driver 6) as shown in FIG. 1, the PWM drive signal pulse-width modulated in the low frequency band is used as the motor drive signal. By using it, when the motor drive circuit receives the H level PWM drive control signal indicating that the motor should be driven from the PWM generation circuit 57, the motor drive circuit (that is, the PWM driver 6) is immediately turned on. In this state, the motor is directly driven to rotate at a low rotation speed.

Here, the motor drive circuit outputs an L level PWM drive control signal indicating that the drive of the motor should be stopped.
When it is received from the WM generation circuit 57, the motor drive circuit (that is, the PWM driver 6) is set as close to the OFF state as possible to prevent wasteful power consumption. However, since the motor itself continues the rotation operation without immediately stopping due to inertia, the smooth rotation operation of the motor is possible even when the next PWM drive control signal of the H level is received. Become. That is, unlike the prior art, the integrated motor drive signal is not used, but the pulse-width-modulated PWM drive signal is used as the motor drive signal. Therefore, power is supplied during the L level section of the PWM drive signal. The power consumption is extremely low, and it is possible to significantly reduce the power consumption as compared with the conventional technology.

However, in the tracking control shown in FIG. 1, when the fluctuation of the load of the drive system is small,
It is possible to realize smooth rotation control at low speed, but the load on the drive system suddenly becomes lighter, or conversely,
If the load becomes heavy or the load fluctuates significantly, the rotation speed changes at the time when the load fluctuates, and smooth rotation control is impaired.

Another example of the embodiment of the motor control circuit according to the present invention and the disc reproducing apparatus using the motor control circuit is provided in order to provide tracking control applicable to such a sudden load change. Will be described with reference to FIG. FIG. 3 is a block configuration diagram showing another example of the embodiment relating to the disc reproducing apparatus using the motor control circuit according to the present invention. As shown in FIG. The tracking control uses two control loops together with the sub control loop.

In FIG. 3, an objective lens provided in the optical pickup for converging a laser beam from the optical pickup to a track on the disk surface,
An actuator serving as an objective lens moving means for moving the objective lens in the radial direction of the disc, and further, operating the objective lens moving means according to a tracking error signal to cause the objective lens to follow a track of the disc. The tracking servo means for that is omitted. Further, in FIG. 3, the same reference numerals are used for the same circuit parts as in FIG. 1 and FIG.
In the following description, description of the same circuit parts as those in FIGS. 1 and 4 will be omitted.

In FIG. 3, 1 is a disk, 2 is an optical pickup, 3 is a sled motor, 4 is a tracking error signal generation circuit, and 5 is a pulse width modulation for driving the sled motor 3 in a low frequency band. The drive control circuit 6 for generating the PWM drive control signal is based on the PWM drive control signal of the low frequency band generated by the drive control circuit 5, and the low frequency band for driving the sled motor 3 (for example, several It is a PWM driver that generates a PWM drive signal of 10 Hz to several hundred Hz.
Further, 8 is a Hall element, and 9 is an amplifier 2.

The drive control circuit 5 includes an AD converter 51, a digital servo processing circuit 152, a speed signal generating circuit 53, a comparator 54, and a digital servo processing circuit 25.
5, an amplifier 156, and a PWM generation circuit 57 are provided.

Here, the amplifier 156 and the PWM generation circuit 57 are exactly the same as the circuit shown in FIG.
Unlike the case of the conventional technique, the generation circuit 57 is subjected to pulse width modulation having an amplitude and a low frequency band (for example, several tens Hz to several hundreds Hz) necessary and sufficient for directly starting the sled motor 3. The PWM drive control signal is generated.

Further, the AD converter 51, the digital servo processing circuit 152, the speed signal generation circuit 53, and the comparator 5
4 and the digital servo processing circuit 255 are the same circuits as in the case of the conventional technique shown in FIG.

In FIG. 3, similarly to the case shown in FIG. 1, the photodetection signal detected by the optical pickup 2 is
The optical pickup 2 is input to the tracking error signal generation circuit 4 and reaches a predetermined track position on the surface of the disk 1.
A tracking error signal for moving the AD converter 51 is generated.
At, it is converted into a digital signal and input to the digital servo processing circuit 152.

In the digital servo processing circuit 152, either the tracking error signal or the signal corresponding to the tracking error signal is converted into a target signal corresponding to the moving amount of the sled motor 3, The difference signal from the speed signal generated by the speed signal generation circuit 53 is input to the digital servo processing circuit 255 through the comparator 54, and the servo amount for driving the sled motor 3 (that is, Error signal) is calculated.

The servo amount is amplified by the amplifier 156 and converted by the PWM generation circuit 57 into a PWM drive control signal which is pulse width modulated in a low frequency band. The converted PWM drive control signal is converted by the PWM driver 6 into a PWM drive signal having the low frequency band for driving the sled motor 3. Then, Figure 1
As in the case of, the PWM drive signal is directly applied to the sled motor 3 as a pulse-width-modulated pulse-shaped motor drive signal, and the sled motor 3 is driven. The above-described motor drive signal generation loop serves as the main control loop.

On the other hand, the output signal (that is, the sled motor speed signal) from the Hall element 8 for detecting the change in the magnetic flux density with the rotation speed of the sled motor 3 as the sled motor speed signal is amplified by the amplifier 29, It is input to the AD converter 51 and converted into a digital signal.
The converted digital signal is generated as a speed signal by the speed signal generation circuit 53 and input to the comparator 54.

The speed signal input to the comparator 54,
The target signal is compared and collated, and the difference signal obtained by subtracting the speed signal from the target signal is generated and input to the digital servo processing circuit 255, and the servo amount for driving the sled motor 3 (that is, , Error signal) is calculated. The servo amount is amplified by the amplifier 156, and the PWM generation circuit 57 generates the PWM drive control signal which is pulse width modulated in a low frequency band (for example, several tens Hz to several hundreds Hz). The PW generated
The M drive control signal is converted into the PWM drive signal for driving the sled motor 3 by the PWM driver 6, and is directly applied to the sled motor 3 as a pulse-width-modulated pulsed motor drive signal. The above motor drive signal generation loop serves as a sub-control loop. That is, in FIG. 3, tracking control is performed using two control loops, the main control loop and the sub control loop.

In FIG. 3, by adding such a sub control loop to the main control loop shown in FIG. 1, even if there is a sudden change in the load of the sled motor drive system, the gear and sled motor 3 It is possible to prevent a situation in which the rotation speed of No. 1 changes, and thus it is possible to maintain smooth rotation control, and thus to realize suitable tracking control. Further, since the sled motor is directly driven by the pulse-width-modulated pulsed PWM drive signal, power consumption in the drive circuit (that is, the PWM driver 6) is low in the L level section of the PWM drive signal. The number of states can be extremely small, and power consumption can be significantly reduced as compared with the conventional technique.

[0067]

According to the motor control circuit and the disc reproducing apparatus using the motor control circuit of the present invention, the ineffective power applied to the sled motor is significantly reduced, and the power consumption of the sled motor is reduced. The sled motor can be greatly reduced, the sled motor can be controlled at a low speed, and the sled motor can be driven smoothly. Therefore, fine tracking control with a very small shift amount of the objective lens from a predetermined track is also possible. It will be possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an embodiment of a disc reproducing apparatus using a motor control circuit according to the present invention.

FIG. 2 is a schematic diagram showing an example of a rotation operation of a sled motor in the motor control circuit according to the present invention shown in FIG.

FIG. 3 is a block configuration diagram showing another example of the embodiment relating to the disc reproducing apparatus using the motor control circuit according to the present invention.

FIG. 4 is a block configuration diagram for explaining a sled motor drive control unit having two control loops, a main control loop and a sub control loop.

FIG. 5 is a schematic diagram showing an example of a rotating operation of a sled motor that moves the position of an optical pickup.

FIG. 6 is a schematic diagram showing an example of a rotation operation of a sled motor that moves a position of an optical pickup when tracking control using a sub control loop and a main control loop is used.

[Explanation of symbols]

1 ... Disc, 2 ... Optical pickup, 3 ... Thread motor, 4 ... Tracking error signal generation circuit, 5, 5 ',
5 "... Drive control circuit, 6, 6 '... PWM driver, 7 ...
Low-pass filter, 8 ... Hall element, 9 ... Amplifier 2, 5
1 ... AD converter, 52, 52 '... Digital servo processing circuit 1, 53 ... Speed signal generating circuit, 54 ... Comparator, 5
5 ... Digital servo processing circuit 2, 56 ... Amplifier 1, 5
7, 57 '... PWM generation circuit.

Claims (5)

[Claims] 1. A motor control circuit comprising a drive circuit for applying a drive signal of a motor starting voltage or a voltage slightly higher than the starting voltage to the monitor to rotate the motor at a low rotation speed, As a result, by using a PWM drive signal that is pulse width modulated in a low frequency band, when the drive circuit receives a signal to drive the motor, the drive circuit is immediately turned on. On the other hand, when receiving a signal to stop driving the motor, the motor control circuit controls the drive circuit as close to the OFF state as possible. 2. The motor control circuit according to claim 1, wherein the frequency band of the PWM drive signal of the low frequency band used as the drive signal is several tens Hz to several hundreds H.
A motor control circuit characterized by being in the range of z. 3. A tracking error signal generating means for generating a tracking error signal indicating a deviation amount of the optical pickup from a predetermined track on a disk surface based on a light detection signal output from the optical pickup, and the optical pickup. A sled motor for moving the track surface onto the predetermined track on the disk surface, the tracking error signal provided from the tracking error signal generating means, or a signal corresponding to the tracking error signal, A sled motor servo means for converting into a target signal corresponding to the moving amount of the sled motor, and a PWM signal generation means for generating a PWM drive control signal pulse-width modulated in a low frequency band based on the target signal. And a disc reproducing apparatus comprising: A disk reproducing device characterized in that the sled motor is directly driven by a PWM drive signal having the low frequency band, which is generated based on the PWM drive control signal of the low frequency band obtained by the PWM signal generating means. . 4. A tracking error signal generating means for generating a tracking error signal indicating a deviation amount of the optical pickup from a predetermined track on a disk surface based on a light detection signal output from the optical pickup, and the optical pickup. A sled motor for moving the track surface onto the predetermined track on the disk surface, the tracking error signal provided from the tracking error signal generating means, or a signal corresponding to the tracking error signal, A sled motor servo means for converting into a target signal corresponding to the moving amount of the sled motor, a speed signal generation means for detecting a rotation speed of the sled motor and generating a speed signal corresponding to the rotation speed, and the target. Generate a difference signal by subtracting the velocity signal from the signal And a PWM signal generation means for generating a PWM drive control signal which is pulse width modulated in a low frequency band based on the difference signal. P
A disk reproducing device characterized in that the sled motor is directly driven by a PWM drive signal composed of the low frequency band created based on the PWM drive control signal of the low frequency band obtained from a WM signal generating means. . 5. The disc reproducing apparatus according to claim 3 or 4, wherein the PWM having the low frequency band created based on the PWM drive control signal of the low frequency band generated by the PWM signal generating means. A disk reproducing device characterized in that the frequency band of the drive signal is in the range of several tens Hz to several hundreds Hz.