JPH07287932A - Spindle servo circuit for optical disk device - Google Patents

Abstract

PURPOSE:To prevent a spindle motor from runaway. CONSTITUTION:The speed of revolution of a spindle motor 8 is detected by using a magnet and a sensor 5 rotating together with the spindle motor 8. When the speed of the the revolution becomes a low speed revolution or a high speed revolution being out of the servo procession possible range by the IC1 for a CD and the IC for a CD-WO, the revolution of the spindle motor 8 is speedily made to be the speed of revolution within the servo procession possible range by switching over the driving control signal of the spindle motor 8 to the driving control signal SP2 outputted from a CAV servo system circuit with a runaway detecting circuit 9. As a result, since the motor becomes possible to be synchronized even when a tracking servo is not applied, even when a track jump is performed, or even at the time of starting the spindle motor 8, etc., the spindle never falls into a runaway state in which the motor 8 rotates at a lower speed or at a higher speed than the speed of a normal time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle servo circuit of an optical disk device, and more particularly to a spindle servo circuit capable of preventing servo runaway.

[0002]

2. Description of the Related Art Conventionally known compact discs include
Pits are formed based on an EFM (Eight to Fourteen Modulation) signal, and frame synchronization information is recorded for each frame. When reproducing the information recorded on the compact disc, the frame synchronization information is detected, a frame synchronization signal is generated based on this, and drive control of the spindle motor or the like is performed based on the frame synchronization signal. .

An IC for CD (commercially available) is used for the spindle servo circuit in the reproducing apparatus for the compact disc, and the drive control of the spindle motor is performed by the control signal output from the IC for CD.

In the above-mentioned IC for CD, the RF signal read from the compact disc is binarized to be EF.
The M signal is converted, the frame signal in the EFM signal is compared with the clock signal, and the servo signal (MDP signal) is output based on the comparison result. The MDP signal is output in a form in which the speed control signal and the phase control signal are added, and the addition ratio at this time is optimized in the IC. The linear velocity is constant (CLV: Constant Lin) by this MDP signal.
The rotation drive of the spindle motor is controlled as the ear velocity. At this time, in the CD IC, since the pull-in range of the spindle servo, that is, the frequency range in which the servo operation can be performed is wide, if the RF signal can be read, there is almost no runaway.

On the other hand, a write-once optical disc (CD-WO)
, A spiral meandering track (wobble) is formed in an area where information is recorded, and the track has a plurality of ATIPs with a time width including the same number of clock signals.
(Absolute Time In Pregroove) It is divided into frames. Further, frame synchronization information, absolute time information, etc. are recorded in each ATIP frame. Further, the synchronization information is composed of a predetermined bit pattern.

Like the write-once type optical disk described above, the information recording area is divided into a plurality of ATIP frames having a time width including the same number of clock signals, and each ATIP frame is located at the same position of each ATIP frame. When information is recorded on an information recording medium on which frame synchronization information corresponding to the above is recorded or when ATIP information recorded on such an information recording medium is reproduced, a dedicated optical disc recording / reproducing apparatus is used. ing.

The information recording / reproducing apparatus for such a write-once optical disc detects the above-mentioned frame synchronization information when recording information or reproducing ATIP information, and the bit pattern of the frame synchronization information is detected. When a predetermined bit pattern, for example, "00010111" or "11101000", a frame sync pulse signal is generated and information is recorded in synchronization with the frame sync pulse signal, or each ATIP frame is recorded. The recorded ATIP information is being reproduced. As a result, the information can be recorded in synchronization with the ATIP frame and the correct time information can be obtained from the ATIP information, so that the information to be recorded can be correctly recorded.

A write-once optical disc IC (commercially available product, hereinafter referred to as an ATIP decoder) is used in the spindle servo circuit in the recording / reproducing apparatus for the above-mentioned write-once optical disc. As in the case of the compact disc described above, the drive control of the spindle motor is performed with a constant linear velocity.

In the ATIP decoder, the wobble signal read from the write-once optical disc is 22.05 KH.
The speed control signal (CLV- signal) and the phase control signal (CLV + signal) are output so as to be z. Furthermore, AT
Outside the IP decoder, the CLV- signal and the CLV + signal are added and the added signal drives the spindle motor. Here, the addition ratio of the CLV- signal and the CLV + signal must be set to an optimum value.

[0010]

However, the above-mentioned ATIP decoder has a narrow pull-in range with respect to the wobble signal frequency and cannot read the wobble signal normally, for example, when the tracking servo is not applied or when the search is performed. Alternatively, at the time of starting the spindle motor or the like, synchronization cannot be achieved, and the spindle motor may fall into a runaway state in which the spindle motor rotates at a lower speed than usual or rotates at a higher speed than usual.

The recording / reproducing apparatus for the write-once type optical disc is also capable of reproducing information on a compact disc.
Since the D-WO requires much information reproduction in the inner circumference area of the compact disc, when reproducing information of the compact disc, the inside of the TOC area, that is, the area in which no pit is formed, is reproduced, and this area is reproduced. In that case, since the EFM signal cannot be reproduced, the spindle motor may run out of control due to lack of synchronization.

In view of the above problems, it is an object of the present invention to provide a spindle servo circuit for an optical disk device which can prevent the spindle motor from running away.

[0013]

In order to achieve the above object, the present invention provides, in claim 1, an optical disk recording / reproducing apparatus for controlling the drive of a spindle motor for rotating the disk based on a signal reproduced from the disk. In a spindle servo circuit, a rotation speed detecting means for detecting the rotation speed of the spindle motor, and based on a detection result of the rotation speed detecting means, the rotation speed of the spindle motor is a predetermined reference lower limit value and a predetermined reference upper limit value. Between the rotation speed of the spindle motor and the rotation speed of the spindle motor based on the detection result of the rotation speed detection means. Second rotation control for rotating the rotation speed of the spindle motor at a predetermined constant rotation speed when the reference lower limit value or less or the reference upper limit value or more Suggest spindle servo circuit of an optical disk apparatus provided with the stage.

According to a second aspect, in the spindle servo circuit of the optical disk device according to the first aspect, the second
The rotation control means of the spindle motor rotates the spindle motor at a predetermined constant rotation speed when the rotation speed of the spindle motor is equal to or lower than the reference lower limit value or higher than the reference upper limit value and when a search is performed. We propose a spindle servo circuit for optical disks.

According to a third aspect of the present invention, in the spindle servo circuit of the optical disc apparatus according to the first or second aspect, the rotation speed detecting means includes an optical disk including a magnet and a magnetic sensor for detecting the strength of the magnetic field from the magnet. The spindle servo circuit of the device is proposed.

According to a fourth aspect of the present invention, in the spindle servo circuit of the optical disc apparatus according to the third aspect, the magnet is provided so as to rotate at a predetermined radius of rotation with the rotation of the spindle motor, and the magnetic sensor is provided. A spindle servo circuit of an optical disk device is proposed which is arranged so as to detect the magnetic field of the magnet at a predetermined position of the magnet's peripheral circuit.

According to a fifth aspect of the present invention, in the spindle servo circuit of the optical disc apparatus according to the fourth aspect, the magnet has an N pole and an S pole on at least a circumferential portion of a circle formed by the turning radius.
We propose a spindle servo circuit for an optical disk device in which poles are alternately arranged at equal intervals.

Further, in claim 6, claim 3, 4 or 5 is provided.
In the spindle servo circuit of the optical disc device described above, the magnetic sensor proposes a spindle servo circuit of the optical disc device including a Hall element.

According to a seventh aspect of the present invention, in the spindle servo circuit of the optical disc apparatus according to the first or second aspect, the rotation speed detecting means rotates together with the light emitting element and the light receiving element and the spindle motor at a predetermined radius of rotation. Then, a spindle servo circuit of an optical disk device including a reflector for reflecting the light emitted from the light emitting element to the light receiving element is proposed.

Further, according to an eighth aspect of the present invention, in the spindle servo circuit of the optical disk apparatus according to the seventh aspect, a plurality of the reflectors are arranged at equal intervals with a non-reflector sandwiched at least at a circumferential portion of a circle formed by the turning radius. We propose a spindle servo circuit for the optical disk drive.

[0021]

According to the first aspect of the present invention, the rotation speed of the spindle motor is detected by the rotation detection means, and the rotation speed of the spindle motor is set to a predetermined reference lower limit value based on the detection result of the rotation speed detection means. And the predetermined reference upper limit value, the first rotation control means rotates the spindle motor so that the rotation speed thereof becomes a predetermined constant linear velocity. When the rotation speed of the spindle motor is less than or equal to the reference lower limit value or greater than or equal to the reference upper limit value, the second rotation control means rotates the spindle motor so that the rotation speed becomes a predetermined constant rotation speed. It Thereby, for example, a write-once optical disc (CD-W
When the wobble signal cannot be read normally during the recording / reproducing of the information to / from (O), and the spindle motor rotates at a speed lower or higher than usual, the rotation control of the spindle motor is performed by the second rotation control means, and the spindle motor is rotated. The rotation speed of the motor is a preset constant rotation speed, for example, when the rotation speed is lower than normal, the rotation speed is set to the rotation speed set to high speed, and when the rotation speed is higher than normal, the rotation speed is low. It is rotated so that the number of rotations is set to the rotation setting. As the rotation control by the second rotation control means is performed, the rotation speed of the spindle motor becomes a rotation speed between the reference lower limit value and the reference upper limit value. At this point, the second rotation control means The rotation control is transferred to the first rotation control means.
As a result, the spindle motor is line-controlled in a normal state, that is, the linear velocity becomes a predetermined constant value.

According to claim 2, a search is performed,
Even when servo control of the spindle motor becomes unstable, the second rotation control means rotates the spindle motor so that the rotation speed of the spindle motor becomes a predetermined constant rotation speed.

According to a third aspect of the present invention, the rotation speed detecting means comprises a magnet and a magnetic sensor for detecting the strength of the magnetic field from the magnet. For example, the magnet is rotated by the spindle motor and the rotation is performed. The rotation speed of the spindle motor is detected based on the signal output from the magnetic sensor in correspondence with the cycle.

According to a fourth aspect of the present invention, the magnet rotates at a predetermined radius of rotation as the spindle motor rotates, and the magnetic field of the magnet is detected by the magnetic sensor at a predetermined position of the magnetic circuit. To be done.

According to a fifth aspect of the present invention, the magnet has the N poles and the S poles alternately arranged at equal intervals on at least the circumferential portion of the circle formed by the radius of gyration. Outputs a signal that changes corresponding to the arrangement of the N and S poles of the magnet.

According to a sixth aspect of the present invention, the magnetic sensor comprises a Hall element, and the Hall element outputs a voltage corresponding to the strength of the magnetic field applied to the Hall element.

According to the seventh aspect, the light emitted from the light emitting element is reflected toward the light receiving element by the reflector that rotates together with the spindle motor at a predetermined rotation radius.

As a result, the rotation speed of the spindle motor is detected based on the signal output from the light receiving element corresponding to the rotation cycle of the reflector.

According to the eighth aspect of the invention, since the plurality of reflectors are arranged at equal intervals with at least the non-reflector sandwiched in at least the circumferential portion of the circle formed by the radius of gyration, the light receiving element is arranged to have the above-mentioned structure. A signal that changes corresponding to the arrangement of the reflector and the non-reflector is output.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a first embodiment of the present invention. In the figure, reference numeral 1 is an IC for a CD, which inputs an EFM signal read from a compact disc.
Compare the frame signal in the signal with the reference clock signal,
Based on the comparison result, a servo signal (MDP signal) obtained by adding the speed control signal and the phase control signal of the spindle motor is output. This MDP signal is a signal having a peak value of 0V and 5V with 2.5V as a reference. Further, the CD IC outputs a switching control signal MON for switching the on / off state of an analog switch in a spindle driver circuit described later, and also outputs an FGS signal when the frequency of the EFM signal falls within a frequency range in which phase control is possible. To do.

Reference numeral 2 is a write-once optical disc (hereinafter referred to as CD-WO
The wobble signal read from the write-once optical disc is input to the ATI
After obtaining the P information, the frame synchronization pulse signal generated from the ATIP information is compared with the reference clock signal, and based on the comparison result, the speed control signal (CLV of the spindle motor).
-) And the phase control signal (CLV +) are output. These speed control signal CLV- and phase control signal CLV + are
The signals have peak values of 0V and 5V with 2.5V as a reference. Further, the CD-WO IC 2 outputs a LOCK signal when the frequency of the wobble signal falls within the frequency range in which the phase can be controlled.

A signal switching circuit 3 inputs the MDP signal output from the CD IC 1 and the CLV + and CLV- signals output from the CD-WO IC, and outputs these signals based on the switching control signal CNT. Is switched to output the rotation control signal SP1 corresponding to the compact disc or the CD-WO disc to be rotated.

The above IC 1 for CD and IC for CD-WO
2 and the signal switching circuit 3 constitute a CLV servo system circuit.

Further, 4 is CAV (Constant Angular Vel
The servo system circuit is composed of an F / V conversion circuit 4a, a high speed rotation setting switch 4b, a low speed rotation setting switch 4c, a search rotation setting switch 4d, and an electronic switch 4e having one circuit and three contacts.

The F / V conversion circuit 4a waveform-shapes and binarizes the FG voltage input from the magnetic sensor 5, integrates it, reads the peak voltage of the integrated waveform, and turns on the electronic switch 4e. The setting value of the high speed rotation setting switch 4b, the setting value of the low speed rotation setting switch 4c input via
Alternatively, based on the set value of the rotation setting switch 4d during search, the value of the peak voltage is set to the setting switches 4b, 4c,
The drive control signal SP2 for the spindle motor is output so as to be equal to the value of 4d. Here, the switching of the electronic switch 4e is performed by a switching control signal CG from a runaway detection circuit 9 described later.
It is performed based on 1.

The magnetic sensor 5 is composed of, for example, a Hall element, and as shown in FIG. 2, it is arranged at a position where the strength of the magnetic field of the rotating magnet portion 10 rotating with the spindle motor 8 described later can be detected. That is, the rotating magnet unit 10 has a substantially cylindrical shape having a predetermined radius, and a plurality of N poles and S poles are alternately arranged at equal intervals in the circumferential direction. Further, the magnetic sensor 5 is arranged at a predetermined position near the outer peripheral portion of the rotary magnet unit 10. As a result, the spindle motor 8
When the rotating magnet unit 10 rotates with the rotation of, the magnetic sensor 5 outputs a sine wave AC voltage corresponding to the magnetic fields of the N pole and the S pole as the FG voltage.

Further, in FIG. 1, reference numeral 6 denotes an electronic switch having one circuit and two contacts, which receives the drive control signal SP1 output from the signal switching circuit 3 and the drive control signal SP2 output from the F / V conversion circuit 4a. , Any one of them is output to the spindle driver circuit 7 based on the switching control signal CG2 input from the runaway detection circuit 9.

The spindle driver circuit 7 applies a drive voltage based on the input drive control signals SP1 and SP2 to the spindle motor 8.

The runaway detection circuit 9 outputs the FG pulse voltage output from the magnetic sensor 5 and the FG output from the CD IC.
The S signal and the LOCK signal output from the CD-WO IC are input, and the rotation speed of the spindle motor 8 is detected based on the FG pulse voltage. As shown in FIG. 3, the rotation speed of the spindle motor 8 is detected as a low rotation speed. When it is within the range, the electronic switch 6 is switched to input the drive control signal SP2 output from the F / V conversion circuit 4a to the spindle driver circuit 7, and the electronic switch 4e is switched to set the set value of the high speed rotation setting switch 4b. Is input to the F / V conversion circuit 4a. As a result, the rotation speed of the spindle motor 8 increases to the rotation speed based on the set value of the high speed rotation setting switch 4b.

When the rotation speed of the spindle motor 8 is within the high rotation detection range, the runaway detection circuit 9 switches the electronic switch 6 to output the drive control signal SP2 output from the F / V conversion circuit 4a to the spindle driver. In addition to being input to the circuit 7, the electronic switch 4e is switched to input the set value of the low speed rotation setting switch 4c to the F / V conversion circuit 4a. As a result, the rotation speed of the spindle motor 8 decreases to the rotation speed based on the set value of the low rotation setting switch 4c. When a search signal SC indicating that track search is being performed is input from a main control unit (not shown),
The electronic switch 6 is switched to input the drive control signal SP2 output from the F / V conversion circuit 4a to the spindle driver circuit 7, and the electronic switch 4e is switched to F / V convert the set value of the rotation setting switch during search 4d. Input to the circuit 4a. As a result, the rotational speed of the spindle motor 8 approaches the rotational speed based on the set value of the search rotation setting switch 4d.

Further, the runaway detection circuit 9 includes the CD IC 1
When the FGS signal indicating that the rotation speed of the spindle motor 8 is within the servo processable range is input, and when the rotation speed of the spindle motor 8 is within the servo processable range from the CD-WO IC2. When the LOCK signal is input, the electronic switch 6 is switched, the drive control signal SP1 output from the signal switching circuit 3 is input to the spindle driver circuit 7, and the spindle motor 8 is rotated by the CLV servo.

Next, the operation of the first embodiment having the above construction will be described. The rotation speed of the spindle motor 8 is detected by using the magnetic sensor 5 including a Hall element utilizing the Hall effect as described above. The output of the magnetic sensor 5 is set to be, for example, 5 pulses per one rotation of the spindle motor 8. When ATIP servo is performed when recording / reproducing to / from a CD-WO disc,
If the wobble signal cannot be correctly read or the rotation speed of the spindle motor 8 is out of the servo pull-in range due to disturbance or the like, and the rotation speed is low or high, CL
The V servo system is switched to the CAV servo system to control the rotation drive of the spindle motor.

That is, when the number of revolutions of the spindle motor 8 becomes lower than the steady state, the number of revolutions of the spindle motor 8 should count the number of pulses of the FG pulse voltage output from the magnetic sensor 5. Since it is constantly monitored by the runaway detection circuit 9, when the rotation speed of the spindle motor 8 enters the low speed rotation detection range, the CLV servo is switched to the CAV servo, and the rotation speed set value of the CAV servo is also in the high rotation detection range. The rotation speed of the spindle motor 8 is increased by the CAV servo by setting the high speed rotation setting value set in the inside.

As the rotation speed of the spindle motor 8 increases, the rotation speed falls within the servo pull-in range. Further, the rotation speed is in a phase controllable range (LOCK range)
When entering, the LOCK signal is sent to the ATIP decoder (CD-W
It is output from the IC for O2) and switches from the CAV servo to the CLV servo.

When the rotation speed of the spindle motor 8 becomes higher than that in the steady state, the rotation speed of the spindle motor 8 enters the high-speed rotation detection range, and the CLV servo is switched to the CAV servo. Further, the rotation speed setting value of the CAV servo is also set to the low speed rotation setting value set within the low speed rotation setting range, and the rotation speed of the spindle motor 8 is lowered by the CAV servo. When the rotation speed decreases, the servo pull-in range is entered, and when the phase controllable range (LOCK range) is entered, a LOCK signal is output and the CAV servo is switched to the CLV servo. Then, the CLV servo works so as to lock the frequency of the wobble signal to the reference clock signal.

Further, since the wobble signal cannot be read correctly even during the track search, the CAV servo is forcibly switched during the track search. The rotation speed setting value of the CAV servo at this time is the rotation speed of the spindle (1.2 m / s, 1.4 m / s disc reproduction when reproducing the innermost circumference of the disc having a linear velocity of 1.4 m / s). The maximum speed is set to the center value of the spindle rotation speed (1.2 m / s, the slowest rotation speed at 1.4 m / s disc reproduction) when the outermost periphery of the 1.2 m / s disc is reproduced. There is.

On the other hand, when reproducing information on a compact disc (CD), the low rotation detection frequency and the high rotation detection frequency are set to be the same as those for the CD-WO disc. It is the same. Also, LOC
Instead of the K signal, the FGS signal that operates in the same manner as the LOCK signal is used.

This FGS signal is output when the frame sync of the EFM signal and the interpolation protection timing match (lock). When this FGS signal is output, CAV
Switch from servo to CLV servo.

The frequency / voltage (F / V) conversion of the F / V conversion circuit 4a is performed as follows. That is,
As shown in FIG. 4, the FG voltage output from the magnetic sensor 5 is waveform-shaped and binarized to obtain an FG pulse, which is then applied to a low-pass filter and integrated, and the peak value of this signal is detected to determine the spindle value. The voltage corresponding to the rotation speed of is obtained.

In order to absorb the variation in the duty of the output of the magnetic sensor 5, the FG pulse is inverted, the above operation is performed, and the outputs after peak detection of both are added. Further, in order to correspond to the double speed, the set value of the rotation speed of the CAV servo system circuit 4 may be doubled.

As described above, according to the first embodiment, the CLV servo system and the CAV servo system are switched based on the rotation speed of the spindle motor 8 to control the rotation of the spindle motor 8. It is possible to synchronize even when the servo is not applied, when searching, or when the wobble signal is not normally read when starting the spindle motor, so the spindle motor rotates at a lower speed than usual. It does not fall into a runaway state in which it runs or rotates at high speed. Further, even when the servo search of the spindle motor 8 becomes unstable due to the track search, the normal rotation can be quickly returned.

In the first embodiment, the plurality of N poles and S poles are alternately arranged in the rotary magnet portion 10, but the present invention is not limited to this, and a part of the rotary magnet portion 10 is provided as shown in FIG. Even if a magnet is provided in, the same effect can be obtained. However, it goes without saying that the detection accuracy of the rotation speed is reduced.

Next, a second embodiment of the present invention will be described.
FIG. 6 is a block diagram showing the essential parts of the second embodiment. As shown in FIG. 6, the difference between the first embodiment and the second embodiment described above is that instead of the rotary magnet unit 10 and the magnetic sensor 5 in the first embodiment, the rotary reflecting unit 20, the light emitting element. 21 and the light receiving element 22 are provided.

That is, the rotary reflecting portion 20 has a substantially disk shape having a predetermined radius and is provided so as to rotate together with the spindle motor 8. Further, on the lower surface of the rotary reflecting portion 20, reflecting portions 20a and non-reflecting portions 20b, which are mirrors, are alternately arranged at equal intervals in the circumferential direction. Further, the light emitting element 21 and the light receiving element 22 are arranged at predetermined positions in the vicinity of the outer peripheral portion of the rotary reflecting portion 20, and the light emitted from the light emitting element 21 is reflected by the one reflecting portion 21, and the light receiving element 22.
It is designed to be incident on. As a result, when the rotation reflecting portion 20 rotates with the rotation of the spindle motor 8,
A rectangular wave voltage corresponding to the reflecting portion 20a and the non-reflecting portion 20b is output from the light receiving element 22 as an FG voltage, and the FG voltage is input to the F / V conversion circuit 4a and the runaway detection circuit 9, whereby the first The number of rotations of the spindle motor 8 can be detected as in the above embodiment. Other configurations and processes are similar to those of the above-described first embodiment, and almost the same effect can be obtained.

Incidentally, as shown in FIG. 7, even if the reflecting portion 20a is provided only in a part of the rotary reflecting portion 20, substantially the same effect can be obtained. However, it goes without saying that the detection accuracy of the rotation speed is reduced.

[0056]

As described above, according to claim 1 of the present invention, the rotation of the spindle motor is switched by switching between the first rotation control means and the second rotation control means based on the rotation speed of the spindle motor. Since the control is performed, it is possible to synchronize even when the wobble signal is not normally read, for example, when the tracking servo is not applied, when the search is performed, or when the spindle motor is started. The spindle motor does not run into a runaway state in which it rotates at a lower speed than usual or rotates at a higher speed than usual.

According to the second aspect, in addition to the above effects, even when the servo control of the spindle motor becomes unstable, the normal rotation can be quickly returned.

According to claim 3, in addition to the above effect, the number of rotations of the spindle motor can be detected in a non-contact manner with respect to the spindle motor and the rotating body rotated by the spindle motor. The rotation of the spindle motor is not hindered by detecting the rotation speed.

According to the fourth aspect, in addition to the above effects, since the magnet that does not require electrical connection is rotated by the spindle motor to detect the rotation speed of the spindle motor, the rotation speed can be detected. The mechanism of the means can be simply constructed.

According to claim 5, in addition to the above effect, the magnetic sensor outputs a signal which changes corresponding to the arrangement of the N pole and the S pole of the magnet. The rotation speed of the spindle motor can be detected with high accuracy by reading

According to claim 6, in addition to the above effect, the magnetic sensor comprises a Hall element, and the Hall element outputs a voltage corresponding to the strength of the magnetic field applied to the Hall element. Therefore, the rotation speed of the spindle motor can be easily detected by a simple circuit that reads the change in the voltage and counts it.

According to claim 7, in addition to the above effect, the rotation speed of the spindle motor is detected based on the signal output from the light receiving element corresponding to the rotation cycle of the reflector. Since the rotation speed of the spindle motor can be detected without contacting the spindle motor and the rotating body rotated by the rotation, the rotation driving of the spindle motor is not hindered by the detection of the rotation speed.

According to the eighth aspect, in addition to the above effect, the light receiving element outputs a signal which changes corresponding to the arrangement of the reflector and the non-reflector which are rotated by the rotation of the spindle motor. Therefore, the rotational speed of the spindle motor can be detected with high accuracy by reading the change state of the signal.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a rotary magnet unit and a magnetic sensor in the first embodiment.

FIG. 3 is a diagram illustrating rotation control according to the first embodiment.

FIG. 4 is a diagram for explaining F / V conversion in the first embodiment.

FIG. 5 is a diagram showing a configuration example of another rotary magnet section according to the first embodiment.

FIG. 6 is a diagram showing a configuration of a rotary reflector, a light emitting element, and a light receiving element in a second embodiment.

FIG. 7 is a diagram showing a configuration example of another rotation reflecting portion according to the second embodiment.

[Explanation of symbols]

1 ... CD IC, 2 ... CD-WO IC, 3 ... Signal switching circuit, 4 ... CAV servo system circuit, 4a ... F / V conversion circuit, 4b ... High speed rotation setting switch, 4c ... Low speed rotation setting switch, 4d ... Rotation setting switch during search, 4e ... Electronic switch, 5 ... Magnetic sensor, 6 ... Electronic switch, 7 ...
Spindle driver circuit, 8 ... Spindle motor, 9 ...
Runaway detection circuit, 10 ... Rotating magnet part, 20 ... Rotating reflecting part,
20a ... Reflecting part, 20b ... Non-reflecting part, 21 ... Light emitting element,
22 ... Light receiving element.

Claims (8)

[Claims] 1. In a spindle servo circuit of an optical disk recording / reproducing apparatus for controlling the drive of a spindle motor for rotating a disk based on a signal reproduced from the disk, a rotational speed detecting means for detecting the rotational speed of the spindle motor, Based on the detection result of the rotation speed detecting means, when the rotation speed of the spindle motor is between a predetermined reference lower limit value and a predetermined reference upper limit value, the rotation speed of the spindle motor is kept at a predetermined constant linear velocity. When the rotation speed of the spindle motor is equal to or lower than the reference lower limit value or equal to or higher than the reference upper limit value, based on the detection result of the first rotation control means for rotating and the rotation speed detection means, the rotation speed of the spindle motor. And a second rotation control means for rotating the optical disc at a predetermined constant number of revolutions. circuit. 2. The second rotation control means controls the rotation speed of the spindle motor when the rotation speed of the spindle motor is equal to or lower than the reference lower limit value or higher than the reference upper limit value and when a search is performed. 2. The spindle servo circuit for an optical disc according to claim 1, wherein the spindle servo circuit is rotated at a predetermined constant number of revolutions. 3. The spindle servo circuit for an optical disk device according to claim 1, wherein the rotation speed detecting means includes a magnet and a magnetic sensor for detecting the strength of the magnetic field from the magnet. 4. The magnet is provided so as to rotate at a predetermined radius of rotation as the spindle motor rotates, and the magnetic sensor detects a magnetic field of the magnet at a predetermined position of a circumferential circuit of the magnet. 4. The spindle servo circuit of the optical disk device according to claim 3, wherein the spindle servo circuit is arranged in 5. The optical disk device according to claim 4, wherein the magnet has N poles and S poles alternately arranged at equal intervals in at least a circumferential portion of a circle formed by the rotation radius. Spindle servo circuit. 6. The spindle servo circuit for an optical disk device according to claim 3, wherein the magnetic sensor is a Hall element. 7. The rotation speed detection means includes a light emitting element and a light receiving element, and a reflector that rotates together with the spindle motor at a predetermined radius of rotation and that reflects light emitted from the light emitting element to the light receiving element. 3. The spindle servo circuit for an optical disk device according to claim 1, further comprising: 8. The spindle servo for an optical disk apparatus according to claim 7, wherein a plurality of the reflectors are arranged at equal intervals with at least a non-reflector sandwiched in at least a circumferential portion of a circle formed by the rotation radius. circuit.