JP4516920B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus.

  The optical disk device drives a spindle motor to rotate an optical disk on which data such as a CD (Compact Disk) is recorded. When the spindle motor is started up, the optical disc apparatus performs rough servo to draw the rotation speed of the spindle motor into a capture range of a PLL (Phase Locked Loop) circuit (for example, see Patent Document 1).

  During reproduction, the optical disc apparatus performs tracking servo so that the optical pickup follows the track, extracts an RF (Radio Frequency) signal as a reproduction signal, and reproduces data. A track is formed in a spiral on the optical disc, and during reproduction, the optical disc apparatus controls the rotation of the spindle motor by a CLV (Constant Linear Velocity) system in which the linear velocity is constant on the optical disc.

  On the other hand, when performing a track search, the optical disc apparatus turns off tracking and performs a track jump or the like. In the CLV system, it is necessary to change the rotation speed of the optical disk between the inner and outer peripheral sides of the optical disk. For this reason, the optical disk apparatus extracts the RF signal and performs rough servo of the spindle motor even when tracking is off.

  Some optical disk apparatuses use the 6T mode when tracking is off. “T” indicates the clock cycle of the modulation signal. The 6T mode is a mode in which a 3T component of an RF signal is extracted, a signal corresponding to 6T is generated by dividing the 3T component signal by 1/2, and spindle control is performed by time comparison.

  When the optical disc is a CD, T = 1 / 4.32 MHz = 231 ns, and the 6T component generated by dividing the 3T component by 1/2 is the shortest pulse width of the EFM-modulated RF signal.

  However, when the optical disk is an optical disk with a large jitter, such as a CD-RW, the conventional optical disk apparatus erroneously extracts high-frequency noise as a 3T component due to the influence of the jitter of the RF signal when off-tracking. End up. If the 3T component is mistaken, the optical disc apparatus erroneously outputs a deceleration signal, and the spindle motor is stopped by this deceleration signal during a long search. In addition, there is a problem that the servo does not converge well and the focus is lowered.

  For this reason, when off-track is detected, there is one in which high-frequency noise is not erroneously extracted as a 3T component by changing a slice level for comparison with an RF signal (see, for example, Patent Document 2). .

Japanese Patent Laid-Open No. 9-027167 (2nd page, FIG. 2) Japanese Patent Laying-Open No. 2005-78669 (page 4, FIG. 1)

  However, even if the slice level is changed at the time of tracking off, if there is a large high-frequency noise, this slice level is exceeded, and the high-frequency noise is erroneously extracted as a 3T component. Further, since the rotation of the spindle motor depends on the RF signal, if high frequency noise is erroneously extracted as a 3T component, it will be affected by the jitter of the RF signal.

  The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an optical disc apparatus capable of controlling the rotation of a spindle motor without being affected by a reproduction signal at the time of tracking off. And

In order to achieve this object, an optical disc apparatus according to the first aspect of the present invention provides:
In an optical disc apparatus that extracts a reproduction signal for data reproduction by tracking a track on which data of the optical disc is recorded,
A spindle motor for rotating the optical disc;
A rotation control signal is generated based on a reproduction signal extracted by tracking the track of the optical disc as a signal for reproducing the data, and the generated rotation control signal is supplied to the spindle motor, and the spindle A spindle motor rotation control unit for controlling the rotation of the motor;
An off-track detection unit that detects a track in which the data is recorded and an off-track in which the data is not recorded and outputs an off-track signal when the tracking is turned off and the track jumps;
A signal control unit that controls supply of the rotation control signal from the spindle motor rotation control unit to the spindle motor when an off-track signal indicating that off-track is detected is output from the off-track detection unit; It is provided with.

The signal controller is
When the off-track signal is not supplied from the off-track detection unit, the spindle motor and the spindle motor rotation control unit are connected, and when the off-track signal is supplied, the off-track signal A first switch unit for controlling the supply of the rotation control signal from the spindle motor rotation control unit to the spindle motor according to the signal level of
A second switch unit that connects or opens between the off-track detection unit and the first switch unit;
During reproduction, the off-track detection unit and the first switch unit are opened, and when the tracking jump is performed with the tracking turned off, the off-track detection unit transfers the off-track to the first switch unit. A switch control unit that connects between the off-track detection unit and the first switch unit so that a signal is supplied may be included.

  The first switch unit includes a low-pass filter that removes a high-frequency component, and when an off-track signal indicating off-track is supplied, the spindle motor rotation control unit passes the low-pass filter to the spindle motor. The supply of the rotation control signal may be controlled by supplying the rotation control signal.

  According to the present invention, at the time of tracking off, the rotation of the spindle motor can be controlled without being affected by the reproduction signal.

Hereinafter, an optical disk device according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows the configuration of the optical disc apparatus according to this embodiment.
The optical disk apparatus according to the present embodiment includes a spindle motor 11, an optical pickup 12, a signal generation circuit 13, a smoothing unit 14, a signal processing unit 15, drivers 16 and 17, an LPF 18, a hold circuit 19, An OFT detection on / off circuit 20 and a controller 21 are provided.

  The spindle motor 11 is a motor for rotating the optical disc 1. The optical disk 1 is a disk-shaped recording medium such as a CD (Compact Disk).

  Incidentally, absolute position (ADIP: Address In Pregroove) information is recorded on the optical disc 1 as a pre-groove, and when a light spot irradiated on the recording surface is track-jumped, the moving direction is determined based on this information. The

  The optical pickup 12 is for reading out data recorded on the optical disc 1, and irradiates the optical disc 1 with a light beam, and based on the reflected light, a light detection signal such as music data recorded on the optical disc 1 Is generated.

  The signal generation circuit 13 generates an RF (Radio Frequency) signal, an FE (focus error) signal, and a TE (tracking error) signal based on the light detection signal output from the optical pickup 12. The FE signal is a signal indicating an error between the focusing distance when the light spot is focused and the distance to the recording surface of the optical disk 1 of the objective lens (not shown) provided in the optical pickup 12. The signal is a signal indicating an error between the center position of the track being read and the position of the light spot on the recording surface of the optical disc 1. The signal generation circuit 13 supplies the FE signal and the TE signal to the signal processing unit 15, and supplies the RF signal to the signal processing unit 15 via the capacitor C0.

  The RF signal is an analog reproduction signal, which is EFM (Eight to Fourteen Modulation) modulated and recorded on the optical disc 1. EFM modulation is a modulation method in which 8-bit data is extended to 14 bits and encoded.

  The signal generation circuit 13 includes an OFT (off-track) detection circuit (not shown). The OFT detection circuit is a circuit that detects a track in which data is recorded and an off-track in which data is not recorded and outputs an OFT signal to the OFT detection on / off circuit 20 when tracking is turned off and a track jump is performed.

  The OFT signal is a signal indicating a track on which data is recorded and an off-track, and is a signal used for seek and track servo pull-in. In the present embodiment, it is assumed that the OFT detection circuit outputs an OFT signal whose signal level is L level when a track is detected and whose signal level is H level when off-track is detected.

  The capacitor C0 is a capacitor for cutting the direct current component of the RF signal generated by the signal generation circuit 13 and allowing only the AC component to pass. One end of the capacitor C0 is connected to the signal generation circuit 13 and the other end is a signal. Connected to the processing unit 15.

  The smoothing unit 14 acquires an average signal level of the RF signal by smoothing the RF signal, and includes a resistor R1 and a capacitor C1. One end of the resistor R1 is connected to the other end of the capacitor C0, one end of the capacitor C1 is connected to the other end of the resistor R1, and the other end of the capacitor C1 is grounded.

  The signal processing unit 15 performs processing of the RF signal, the FE signal, and the TE signal generated by the signal generation circuit 13, and includes a phase compensation circuit 31, a comparator 32, a demodulation circuit 33, a signal switching unit 34, And a PLL circuit 35.

  The phase compensation circuit 31 performs phase compensation of the FE signal and TE signal generated by the signal generation circuit 13, and outputs the phase compensated FE signal and TE signal to the driver 16.

  The comparator 32 compares the signal level of the RF signal extracted from the optical disc 1 with the slice level, and generates a digital RF signal based on the comparison result. The RF signal is supplied via the capacitor C0. . The + terminal (non-inverting input terminal) of the comparator 32 is connected to the other end of the capacitor C0, and the − terminal (inverting input terminal) is connected to a connection point between the resistor R1 and the capacitor C1.

  The demodulation circuit 33 is for demodulating music data and the like based on the digital RF signal output from the comparator 32. The demodulating circuit 33 detects a synchronization signal from the digital signal output from the comparator 32, identifies the delimiter of each data, demodulates the EFM modulated signal in each frame, and converts the demodulated signal into 8-bit digital data. Convert.

  The signal switching unit 34 is for switching a signal supplied to the PLL circuit 35 during reproduction and rough servo. As shown in FIG. 2, the signal switching unit 34 includes changeover switches 41 and 43 and a frequency divider 42.

  The frequency divider 42 is for extracting a 3T component from an EFM-modulated RF signal and dividing the frequency by 1/2 to generate a 6T component when tracking is off. This 3T component is a signal component whose time interval changes according to the rotation speed of the spindle motor 11.

  The changeover switches 41 and 43 are for switching signals between reproduction and rough servo. The signal switching unit 34 is controlled by the controller 21 and switches the changeover switches 41 and 43 to turn on and off the circuit of the frequency divider 42 during reproduction.

  The signal switching unit 34 is configured as described above. During reproduction, the signal switching unit 34 extracts the 3T component of the RF signal and supplies it to the PLL circuit 35. During rough servo, the signal switching unit 34 divides this 3T component by 1/2 and outputs a signal equivalent to 6T. This is supplied to the PLL circuit 35.

  The PLL circuit 35 is a circuit for synchronizing the signal supplied from the signal switching unit 34 with a frequency signal having a reference frequency. The PLL circuit 35 includes a frequency divider 51, a phase comparator 52, a filter 53, and a VCO 54.

  The frequency divider 51 divides the frequency of the frequency signal output from the VCO 54 based on the data supplied from the controller 21.

  The phase comparator 52 compares the phase of the signal supplied from the signal switching unit 34 with the phase of the signal supplied from the frequency divider 51 and outputs a phase difference signal indicating the phase difference between the two signals. It is.

  The filter 53 is for passing only a low-frequency component having a frequency equal to or lower than a preset cutoff frequency of the phase difference signal output from the phase comparator 52.

A VCO (Voltage Controlled Oscillator) 54 generates a signal having a frequency based on the voltage level of the signal output from the filter 53.
The PLL circuit 35 outputs an error signal synchronized with the frequency signal to the hold circuit 19 as a rotation control signal.

  The driver 16 controls the position and orientation of the optical pickup 12 based on the FE signal and the TE signal output from the phase compensation circuit 31 of the signal processing unit 15. The driver 17 drives the spindle motor 11.

  An LPF (low-pass filter) 18 is a filter for removing a low-frequency component of the signal output from the hold circuit 19 and supplying the signal to the driver 17. The input end of the LPF (low-pass filter) 18 is as shown in FIG. The output terminal is connected to the input terminal of the driver 17.

The hold circuit 19 and the OFT detection on / off circuit 20 are for controlling the supply of the rotation control signal from the PLL circuit 35 to the LPF 18.
The hold circuit 19 connects the spindle motor 11 and the PLL circuit 35 via the LPF 18 when the OFT signal is not supplied from the signal generation circuit 13, and the off-track signal when the OFT signal is supplied. The error signal is supplied from the PLL circuit 35 to the spindle motor 11 in accordance with the signal level.

  As shown in FIG. 2, the hold circuit 19 includes a switch having contacts q1, q2, q3, a resistor R2, and a capacitor C2.

  The resistor R2 and the capacitor C2 constitute a low-pass filter, and one end of the resistor R2 and the contact point q1 are connected to the output end of the VCO 54. The contact q2 is connected to the other end of the resistor R2. One end of the capacitor C2 is connected to the other end of the resistor R2 and the contact point q2, and the other end is grounded.

  At the time of reproduction, the hold circuit 19 is not supplied with the OFT signal from the signal generation circuit 13, connects the contact q 1 and the contact q 3, and supplies the 3T component signal supplied from the PLL circuit 35 to the LPF 18 as it is.

  As shown in FIG. 2, the OFT detection on / off circuit 20 is constituted by a switch circuit having contacts p1, p2, and p3. The contact point p1 is grounded, and the contact point p2 is connected to the signal generation circuit 13.

  The OFT detection on / off circuit 20 connects the contact point p1 and the contact point p3, or the contact point p2 and the contact point p3 based on the control signal supplied from the controller 21. Then, the OFT detection on / off circuit 20 supplies an H level or L level signal to the hold circuit 19 through the contact point p3.

  The OFT detection on / off circuit 20 supplies an L level signal to the hold circuit 19 to connect the contact q1 and the contact q3 of the hold circuit 19. The hold circuit 19 supplies the frequency signal output from the PLL circuit 35 to the LPF 18 when the contact q1 and the contact q3 are connected.

  The OFT detection on / off circuit 20 supplies an H level signal to the hold circuit 19 to connect the contact q2 and the contact q3 of the hold circuit 19. When the contact q2 and the contact q3 are connected to the hold circuit 19, the low-pass filter constituted by the resistor R2 and the capacitor C2 removes a high frequency component from the frequency signal output from the PLL circuit 35. The hold circuit 19 supplies the low frequency component of the frequency signal to the LPF 18.

  The controller 21 controls the optical disk device, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown). The controller 21 controls the spindle motor 11 during reproduction and tracking off.

  Specifically, the controller 21 controls the changeover switches 41 and 43 of the signal switching unit 34 so that the RF signal output from the comparator 32 of the signal processing unit 15 is supplied to the PLL circuit 35 during reproduction.

  Further, when performing rough servo, the controller 21 controls the changeover switches 41 and 43 of the signal changeover unit 34 so that the RF signal output from the comparator 32 is supplied to the frequency divider 42.

  Further, the controller 21 supplies the frequency division data d1 for controlling the phase of the reproduction clock signal to the frequency divider 51 of the PLL circuit 35 at the time of reproduction, and the signal output from the frequency divider 51 is preliminarily supplied at the time of rough servo. The frequency-divided data d2 that provides the set 6T component is supplied.

  Further, the controller 21 connects the contact p1 and the contact q3 of the OFT detection on / off circuit 20 so that an L level signal is supplied to the hold circuit 19 during reproduction. On the other hand, the controller 21 controls to connect the contact point p2 and the contact point p3 so that the OFT signal is supplied to the hold circuit 19 during rough servo.

Next, the operation of the optical disc apparatus according to the embodiment will be described.
When the optical disk 1 is set on a turntable (not shown), the controller 21 rotates the spindle motor 11 via the driver 17.

  The controller 21 moves the optical pickup 12 to the initial position (the innermost circumference of the optical disc 1) via the driver 16. The controller 21 turns on automatic servo adjustment and all servos.

  The optical pickup 12 irradiates the optical disk 1 with a laser beam, detects the return light reflected by the optical disk 1, and converts the detected return light into an electric signal having a signal level corresponding to the intensity. . Then, the optical pickup 12 outputs the converted electric signal.

  The signal generation circuit 13 generates an RF signal, an FE signal, and a TE signal based on the signal output from the optical pickup 12.

  The phase compensation circuit 31 of the signal processing unit 15 performs phase compensation of the FE signal and the TE signal generated by the signal generation circuit 13 and supplies the phase compensated FE signal and TE signal to the driver 16.

  The driver 16 controls the position and posture of the optical pickup 12 based on the FE signal and the TE signal.

  The AC component of the RF signal is supplied to the + terminal of the comparator 32 via the capacitor C0. The direct current component of the RF signal is supplied to the negative terminal of the comparator 32 via the capacitor C0.

  The comparator 32 compares the signal level of the direct current component of the RF signal with the signal level of the alternating current component, and outputs a signal based on the comparison result.

  The demodulation circuit 33 demodulates the signal output from the comparator 32 and supplies the demodulated signal to the controller 21. The controller 21 performs servo switching control based on the supplied demodulated signal.

The controller 21 executes this servo switching control according to the flowchart shown in FIG.
First, the controller 21 determines whether or not reproduction is in progress (step S11).
If it is determined that playback is in progress (Yes in step S11), the controller 21 connects the contacts p1 and p3 of the OFT detection on / off circuit 20 (step S12).

  The controller 21 controls the changeover switches 41 and 43 so as to open the path of the frequency divider 42 of the signal switching unit 34 (step S13).

  The controller 21 supplies the frequency division data d1 to the frequency divider 51 of the PLL circuit 35 (step S14).

  On the other hand, if the controller 21 determines that the reproduction is not being performed (No in step S11), the controller 21 connects the contacts p2 and p3 of the OFT detection on / off circuit 20 (step S15).

  The controller 21 controls the changeover switches 41 and 43 so that the RF signal output from the comparator 32 of the signal processing unit 15 is supplied to the frequency divider 42 of the signal switching unit 34 (step S16).

  The controller 21 supplies the frequency division data d2 to the frequency divider 51 of the PLL circuit 35 (step S17).

Next, the operation of each part when the controller 21 performs such servo switching control will be described.
In the case of data reproduction (Yes in step S11), when the controller 21 connects the contacts p1 and p3 of the OFT detection on / off circuit 20 (step S12 processing), the OFT detection on / off circuit 20 sends an L level signal to the hold circuit 19. The contact q1 and the contact q3 of the hold circuit 19 are connected.

  When the controller 21 executes the process of step S13, the changeover switches 41 and 43 of the signal switching unit 34 connect the output terminal of the comparator 32 and the phase comparator 52 of the PLL circuit 35, and the signal switching unit 34 The 3T component of the RF signal is supplied to the phase comparator 52 of the PLL circuit 35.

  The controller 21 supplies the frequency-divided data d1 to the frequency divider 51 of the PLL circuit 35 (processing in step S14), and the frequency divider 51 sets the frequency of the frequency signal output from the VCO 54 to the data supplied from the controller 21. Divide based on d1. The PLL circuit 35 outputs to the hold circuit 19 an error signal that synchronizes the 3T component signal of the RF signal with the reference frequency signal.

  The hold circuit 19 is connected to the contact point q1 and the contact point q3, and supplies the error signal output from the PLL circuit 35 to the LPF 18. The LPF 18 removes a high frequency component from the error signal supplied from the PLL circuit 35 via the hold circuit 19 and supplies the low frequency component of the error signal to the driver 17.

  Based on this signal, the driver 17 controls the rotation of the spindle motor 11 to be driven. In this way, spindle servo during reproduction is performed so as to follow the track of the optical disc 1.

  Next, in the case of a track jump (No in step S11), when the controller 21 connects the contact p2 and the contact p3 of the OFT detection on / off circuit 20 (step S15 processing), the OFT detection on / off circuit 20 holds the OFT signal. This is supplied to the circuit 19.

  When the controller 21 executes the processes of steps S16 and S17, the signal switching unit 34 divides the 3T component of the RF signal by 1/2 to generate a signal equivalent to 6T, and the PLL circuit 35 corresponds to 6T. And the difference is output as an error signal.

  As shown in FIG. 4B, when the signal level of the OFT signal is L level, the OFT detection on / off circuit 20 connects the contact q1 and the contact q3 of the hold circuit 19. The hold circuit 19 supplies the error signal output from the PLL circuit 35 to the LPF 18. The LPF 18 supplies this error signal to the driver 17, and the driver 17 drives the spindle motor 11 according to this error signal as shown in FIG.

  On the other hand, as shown in FIG. 4B, when the signal level of the OFT signal becomes H level, the contact q2 and the contact q3 of the hold circuit 19 are connected by the OFT detection on / off circuit 20. The hold circuit 19 removes the high frequency component from the 6T component signal output from the PLL circuit 35 and supplies only the low frequency component of this signal to the LPF 18.

  The LPF 18 supplies this signal to the driver 17, and the driver 17 supplies only the held voltage to the spindle motor 11 to maintain the rotation of the spindle motor 11. Therefore, even if the optical disc apparatus erroneously extracts high frequency noise as a 3T component due to the influence of the jitter of the RF signal in the off-track section, the driver 17 drives the spindle motor 11 without being affected by this influence.

  As described above, according to the present embodiment, the controller 21 connects the contact point p2 and the contact point p3 of the OFT detection on / off circuit 20 and supplies the OFT signal to the hold circuit 19 at the time of tracking off. When the off-track detection circuit of the signal generation circuit 13 detects off-track and the signal level of the OFT signal becomes H level, the hold circuit 19 removes the high frequency component from the rotation control signal output from the PLL circuit 35. The rotation control signal is held by outputting the signal to the LPF 18.

  Accordingly, even when high frequency noise is erroneously extracted as the 3T component of the RF signal due to the jitter of the RF signal at the time of tracking off, the rotation of the spindle motor 11 can be controlled without being affected by this.

  In addition, the hold circuit 19 does not cut off the supply of the rotation control signal from the PLL circuit 35 to the LPF 18 but supplies only the held voltage to the spindle motor 11 so that the spindle motor 11 is only on track. It is possible to maintain the rotation of the optical disc 1 by being driven according to the above signal.

In carrying out the present invention, various forms are conceivable and the present invention is not limited to the above embodiment. For example, when the optical disc 1 is a CD, the present embodiment can be applied to the 11T mode in which the spindle is locked at the lowest frequency of the RF signal.
Further, the present embodiment can be applied to the 4T mode for media having the shortest pulse width of 2T.

  The optical disk 1 is not limited to a CD, and may be various optical disks such as an MD (Mini Disk), an MO (Magneto Optical disk), and a DVD (Digital Versatile Disk).

1 is a block diagram illustrating a configuration of an optical disc device according to an embodiment of the present invention. It is a block diagram which shows the detailed structure of the optical disk apparatus shown in FIG. It is a flowchart which shows the servo switching control of the controller of FIG. It is a wave form diagram which shows the operation | movement at the time of tracking off of the optical disk of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 11 Spindle motor 12 Optical pick-up 13 Signal generation circuit 14 Smoothing part 16, 17 Driver 19 Hold circuit 20 OFT detection ON / OFF circuit 21 Controller 34 Signal switching part 35 PLL circuit

Claims (3)

In an optical disc apparatus that extracts a reproduction signal for data reproduction by tracking a track on which data of the optical disc is recorded,
A spindle motor for rotating the optical disc;
A rotation control signal is generated based on a reproduction signal extracted by tracking the track of the optical disc as a signal for reproducing the data, and the generated rotation control signal is supplied to the spindle motor, and the spindle A spindle motor rotation control unit for controlling the rotation of the motor;
An off-track detection unit that detects a track in which the data is recorded and an off-track in which the data is not recorded and outputs an off-track signal when the tracking is turned off and the track jumps;
A signal control unit that controls supply of the rotation control signal from the spindle motor rotation control unit to the spindle motor when an off-track signal indicating that off-track is detected is output from the off-track detection unit; With
An optical disc device characterized by the above. The signal controller is
When the off-track signal is not supplied from the off-track detection unit, the spindle motor and the spindle motor rotation control unit are connected, and when the off-track signal is supplied, the off-track signal A first switch unit for controlling the supply of the rotation control signal from the spindle motor rotation control unit to the spindle motor according to the signal level of
A second switch unit for connecting or releasing between the off-track detection unit and the first switch unit;
During reproduction, the off-track detection unit and the first switch unit are opened, and when the tracking jump is performed with the tracking turned off, the off-track detection unit transfers the off-track to the first switch unit. A switch control unit that connects between the off-track detection unit and the first switch unit so that a signal is supplied,
The optical disc apparatus according to claim 1, wherein: The first switch unit includes a low-pass filter that removes a high-frequency component, and when an off-track signal indicating off-track is supplied, the spindle motor rotation control unit passes the low-pass filter to the spindle motor. Controlling the supply of the rotation control signal by supplying a rotation control signal;
The optical disk apparatus according to claim 2, wherein

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