JPH11203691A - Pull-in method of optical disk device and focus servo - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device, etc., rapidly and surely discriminating optical disks with different reflectance from each other. SOLUTION: An optical disk device 1 records and reproduces a high reflectance CD(compact disk) and a low reflectance CD-RW(compact disk rewritable). When a focus servo is pulled in, the optical disk device 1 moves away an objective lens 23 from the optical disk from a position fully close to the optical disk. in this case, an RF signal level is measured in the neighborhood of the focal point, and the disk is discriminated by detecting the reflectance of the optical disk from the RF signal. The optical disk device 1 changes over amplification factors of an RF amplifier, etc., based on the result of the discrimination. And, after the objective lens 23 has been sufficiently moved away from the optical disk, the objective lens 23 is made to approach to the optical disk again, and the servo is switched on in the neighborhood of the focal point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus which performs recording and / or reproduction in correspondence with optical disks having different reflectivities and discriminates the type of the loaded optical disk, and also supports optical disks having different reflectivities. The present invention relates to a focus servo pull-in method used when performing recorded and / or reproduced data.

[0002]

2. Description of the Related Art In recent years, a wide variety of optical disks have been widely developed, and optical disk drive devices corresponding to these optical disks have been developed at the same time.

[0003] For example, a compact disk (hereinafter referred to as C) developed as a read-only digital audio disk.
Called D. ), Compact disc recordable (hereinafter, referred to as CD-R) developed as a write-once disc, compact disc rewritable (hereinafter, referred to as CD-RW) capable of rewriting data, and the like. Optical disk drive devices corresponding to the above optical disks have been developed at the same time.

In addition, these CD, CD-R, CD-RW
Is a disk-shaped recording medium having a diameter of 12 cm and the same size, and in consideration of user's convenience, a disk drive device corresponding to all these disks has been developed.

[0005] By the way, these CD, CD-R, CD-
In optical disk drive devices corresponding to all RWs,
When performing a recording or reproducing operation, it is necessary to switch an internal circuit or the like according to the type of the optical disk. For example,
Since the reflectivity of a CD and a CD-R is about 65%, while the reflectivity of a CD-RW is only about 15 to 25%, a reproduction (RF) signal, a focus error (FE) signal, and a tracking error ( TE) RF for generating signals, etc.
The amplifier gain must be switched.

Accordingly, these CDs, CD-Rs, CD-Rs
In the optical disk drive device corresponding to all of the W, a discrimination process of the loaded optical disk is performed as a pre-process for switching internal circuits and the like.

Here, the discrimination process between a CD (CD-R) and a CD-RW performed in a conventional optical disk drive will be described. In this conventional disk drive device, a CD (CD-
R) and CD-RW.

First, a conventional optical disk drive device
Set the power of the emitted laser light to the reproduction level,
The amplification factor of the amplifier is set for a highly reflective CD (CD-R).

The conventional optical disk drive performs the pull-in operation of the focus servo in this set state. The pull-in operation of the focus servo means that the objective lens of the optical pickup is forcibly moved up and down in the optical axis direction of the laser beam, and the detected RF signal is at a predetermined level or more and the FE signal becomes 0. This is the operation of turning on the focus servo loop.

The conventional optical disk drive device uses the R
When the focus servo is retracted in a state where the amplification factor of the F amplifier is set to an amplification factor corresponding to a CD (CD-R) having a high reflectance, the loaded optical disk becomes a CD (CD).
-R).

If the focus servo cannot be performed even after performing the pull-in operation three times in this setting state, it is determined that the loaded optical disk is not a CD (CD-R). That is, it is determined that a sufficient RF signal cannot be detected because the reflectance of the loaded optical disk is low, and the recording or reproducing operation is started by switching the internal circuit or the like. Subsequently, the power of the emitted laser light is set to a reproduction level, and the amplification factor of the RF amplifier is set to an amplification factor corresponding to a CD-RW having a low reflectance.

The conventional optical disk drive performs the pull-in operation of the focus servo in this setting state. In a conventional optical disk drive, when the focus servo is retracted in a state where the amplification factor of the RF amplifier is set to an amplification factor corresponding to a CD-RW having a low reflectance,
It is determined that the loaded optical disc is a CD-RW.
If the focus servo cannot be performed even after performing the pull-in operation three times in this setting state, the CD (CD-
R), it is determined that neither CD-RW is loaded. That is, it is determined that there is no reflected light from the optical disc and that no RF signal can be detected.

As described above, in the conventional optical disk drive device, the discrimination between the CD (CD-R) and the CD-RW can be made, and the subsequent switching of the internal circuit and the like can be performed. In the optical disk drive, for example,
After the focus servo is pulled in, the tracking error signal is detected, and it is determined whether or not the wobble signal given from the meandering component of the pregroove of the optical disc can be extracted from the tracking error signal.
D-R can be determined.

[0014]

However, in the conventional optical disk drive apparatus, since the pull-in operation of the focus servo is repeatedly performed a plurality of times, a very large amount of time is spent on the optical disk discriminating process. Therefore, it has been difficult for the conventional optical disk drive device to quickly determine the optical disk.

The present invention has been made in view of such circumstances, and an optical disk apparatus for quickly and reliably discriminating optical disks having different reflectances, and a focusing device for quickly and reliably discriminating optical disks having different reflectances. It is an object of the present invention to provide a focus servo pull-in method for performing servo pull-in.

[0016]

An optical disk device according to the present invention is an optical disk device that performs recording and / or reproduction corresponding to a first optical disk and a second optical disk having different reflectivities, and collects laser light. An optical pickup that has an objective lens that emits light, emits laser light via the objective lens, detects reflected light thereof, and outputs a detection signal corresponding to the reflected light; and Generating a reproduction signal of the optical disk and a focus error signal indicating an error between the focus position of the laser beam emitted from the optical pickup and the recording surface of the optical disk. The amplification factor is set in accordance with the second optical disc having a high level, and the generated reproduction signal and focus error signal are amplified at the set amplification factor and output. Amplifying means, focus servo control for moving the objective lens of the optical pickup in the optical axis direction of the laser light based on the focus error signal to match the focus position of the laser light with the position of the recording surface of the optical disc, and Focus servo means for performing pull-in control of focus servo control, wherein the focus servo means moves the objective lens sufficiently close to the optical disc and then moves the objective lens away from the optical disc, and the reproduction signal is equal to or higher than a predetermined level. And detecting the level of the reproduced signal near the position of the objective lens where the focus error signal becomes zero, and if the detected level of the reproduced signal is lower than a predetermined threshold, the amplification factor of the generation / amplification means is increased. The amplification factor is set to correspond to the first optical disk, and the level of the detected reproduced signal is set. The second but the amplification factor of the generation amplifying means is higher than a predetermined threshold value
The objective lens is moved far enough from the optical disc, and then moved so as to approach the optical disc. The position where the reproduction signal is above a predetermined level and the focus error signal becomes zero is set. , The focus servo control for starting the focus servo control is performed in the vicinity of.

In this optical disk apparatus, the objective lens is moved away from the optical disk, and the level of the reproduced signal is detected near the position of the objective lens where the reproduced signal is above a predetermined level and the focus error signal becomes zero. Then, the reflectivity of the optical disk is determined, the objective lens is moved so as to approach the optical disk, and pull-in control of focus servo control is performed.

The pull-in method of the focus servo is to convert a reproduction signal of the optical disk and a focus error signal generated from a detection signal of the optical pickup into a first signal having a low reflectance.
Focus servo used when performing recording and / or reproduction corresponding to the first optical disc and the second optical disc having different reflectivities by amplifying with an amplification factor corresponding to the first optical disc and the second optical disc having a high reflectivity. And moving the objective lens away from the optical disk after bringing the objective lens of the optical pickup sufficiently close to the optical disk, so that the reproduction signal is at or above a predetermined level and the focus error signal becomes zero. The level of the reproduced signal is detected near the position of the lens, and if the detected level of the reproduced signal is lower than a predetermined threshold, the amplification factor is set to the amplification factor corresponding to the first optical disc. If the level is higher than a predetermined threshold, the gain is set to the amplification factor corresponding to the second optical disc, and the objective lens is set to the optical disc. Moves from sufficiently away from click to close the objective lens to the optical disk, the reproduction signal is characterized by starting the focus servo control in the vicinity of a position where the focus error signal to a predetermined level or more is zero.

In this focus servo pull-in method, the objective lens is moved away from the optical disk, and the reproduced signal is at or above a predetermined level and the focus error signal becomes zero near the position of the objective lens where the focus error signal becomes zero. The level is detected, the reflectivity of the optical disk is determined, and this objective lens is moved closer to the optical disk to start focus servo control.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disk drive according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of an optical disk drive according to an embodiment of the present invention.

The optical disk drive 1 emits a laser beam onto the optical disk D and detects the reflected light, and a reproduction (RF) signal, a focus error (FE) signal, An RF amplifier 3 for generating a tracking error (TE) signal and the like; a tracking servo circuit 4 for performing predetermined phase compensation on the TE signal; and a two-axis actuator 25 included in the optical pickup 2 by amplifying the phase compensated TE signal. And a wobble signal demodulation circuit 6 for demodulating a wobble signal included in the TE signal.

Also, the optical disk drive device 1
Focus servo circuit 7 for performing predetermined phase compensation on signals
A search signal generating circuit 8 for generating a search signal for pulling in a focus servo; a switch 9 for switching between the search signal and the FE signal whose phase has been compensated; and a search signal or phase switched and supplied to the switch 9 A focus amplifier 10 for amplifying the compensated FE signal to drive a two-axis actuator 25 included in the optical pickup 2; a system controller 11 to which an RE signal, an FE signal, a wobble signal, and the like are supplied to perform focus pull-in control and the like; It has.

Such an optical disk drive device 1 includes:
After the optical disc D is loaded and the type of the optical disc D is determined, data is recorded on the optical disc D, or
Reproduction of data from the optical disk D is performed. In such an optical disk drive device 1, as the optical disk D, recording or reproduction of a CD and a CD-R having a reflectance of about 65% or a CD-RW having a reflectance of 15 to 25% is performed.

The optical pickup 2 has a center wavelength of 780.
It has a laser diode 21 that emits laser light of nm. The optical pickup 2 irradiates a track of the optical disk D via an optical system including, for example, a polarization beam splitter 22 and an objective lens 23, and detects the reflected light using a photodetector 24. This objective lens 2
The numerical aperture NA of 3 is, for example, 0.45. Further, the optical pickup 2 has a two-axis actuator 25 for moving the objective lens 23 so that the laser beam irradiated on the optical disc D becomes just focus and just track. The biaxial actuator 25 is driven by the tracking amplifier 5 described later to move the objective lens 23 in a direction parallel to the optical axis direction of the laser beam and in the radial direction of the optical disc D, so that the laser spot moves on the track. Tracking servo control is performed so as to be located at the center, and the objective lens 23 is moved in the optical axis direction of the laser light, and focus servo control is performed so that the focal position of the laser light coincides with the recording surface.

Photodetector 2 of optical pickup 2
4 generates a detection signal by detecting the reflected light of the laser light,
The detection signal is supplied to the RF amplifier 3.

The RF amplifier 3 converts a detection signal from the photodetector 24 into a voltage value, and outputs an RF signal, an FE signal,
Generate a TE signal and the like. The RF signal is a signal indicating information recorded on the optical disc D. This RF signal
It is detected based on the difference in reflectance between the formed pits and the recording surface, for example, based on the total amount of light reflected from the optical disc D. The FE signal is a signal indicating an error between the focal position of the laser beam and the recording surface of the optical disc D, and is generated using, for example, a method called astigmatism method. The TE signal is a signal indicating an error between the irradiation position of the laser spot on the optical disk D and the center position of the track of the optical disk D. For example, the TE signal is obtained from both edges of a pre-groove called 1-beam push-pull or differential push-pull. It is generated using a method of detecting a difference signal of reflected light.

For example, when the photodetector 24 comprises a four-divided photodetector as shown in FIG.
The F amplifier 3 outputs the RE signal, the FE signal, the TE signal as follows.
Generate a signal.

That is, the RF amplifier 3 calculates the total amount of reflected light detected by the photodetector 24 to generate an RF signal. That is, the RF amplifier 3 generates the RE signal by calculating A + B + C + D from the detection signal of the four-division photodetector. Also, the RF amplifier 3
An FE signal is generated by calculating the balance of the light amount distribution centered on the midpoint of the reflected light detected via the astigmatism lens. That is, the RF amplifier 3 generates the FE signal by calculating (A + C)-(B + D) from the detection signal of the four-division photodetector. RF amplifier 3
Calculates the difference in the amount of light obtained in each area when divided by the central axis φ parallel to the tangential direction of the track of the photodetector to generate a TE signal. That is, the RF amplifier 3
Is obtained from the detection signal of the 4-split photodetector, (A +
D) Generate a TE signal by calculating-(B + C). Since the CD-R and the CD-RW have a meandering pre-groove, this CD-R or CD-RW
The wobble signal corresponding to the meandering is included in the TE signal obtained from -RW.

In such an RF amplifier 3, an RF signal,
The amplification factor when the FE signal and the TE signal are generated is switched by the system controller 11 described later according to the type of the optical disc D. That is, since the reflectivity of the CD and the CD-R is about 65% and the reflectivity of the CD-RW is as low as 15 to 25%, the RF with the same amplification factor
When a signal or the like is generated, for example, RF of CD and CD-R
The signal level becomes very large,
The level of the RF signal of the CD-RW or the like becomes extremely small, and the sensitivity cannot be unified. Therefore, in the RF amplifier 3, the CD (or CD-R) and the CD
The sensitivity is adjusted by switching the amplification factor with -RW.

The RF signal thus generated is represented by the R
The signal is supplied from the F-amplifier 3 to an RF signal processing unit (not shown) and the like.
The data is subjected to error correction processing and the like, and is supplied to an external device via an interface. The RF signal is also supplied to the system controller 11.

The FE signal is sent from the RF amplifier 3 to the focus servo circuit 7 and the system controller 11.
Supplied to

The TE signal is supplied from the RF amplifier 3 to the tracking servo circuit 4 and the wobble signal demodulation circuit 6.

The tracking servo circuit 4 removes disturbances irrelevant to the tracking servo loop control, for example, wobble signal components and data components, and absorbs disturbances due to the eccentricity of rotation of the optical disk to reduce the low frequency range. Is supplied to the tracking amplifier 5 by performing phase compensation so as to gain open loop servo gain.

The tracking amplifier 5 drives the tracking actuator of the biaxial actuator 25 based on the phase-compensated TE signal, moves the objective lens 23 so that the tracking error becomes zero, and irradiates the optical disk D. Control is performed so that the laser spot follows the center of the track.

The wobble signal demodulation circuit 6 detects a wobble signal contained in the high frequency of the TE signal, and records an ATIP (Absolute Time In Pre) recorded as the wobble signal.
groove) signal. This wobble signal is
It is detected only from CD-R and CD-RW, but not from CD. The detected ATIP signal and its synchronization signal are supplied to the system controller 11.

The focus servo circuit 7 performs phase compensation of the FE signal so as to remove disturbances unrelated to the focus servo loop control, for example, data components and the like.
It is supplied to the focus amplifier 10 via the switch 9.

The search signal generating circuit 8 generates a search signal supplied to the focus actuator of the biaxial actuator 25 at the time of the focus servo pull-in operation. When this search signal is supplied via the focus amplifier 10, the biaxial actuator 25
3 is moved up and down within the movable range.

The switch 9 is connected to the system controller 11
The switching is controlled, and the FE signal phase-compensated by the focus servo circuit 7 and the search signal generated by the search signal generation circuit 8 are switched and supplied to the focus amplifier 10. The switch 9 is switched to the focus servo circuit 7 at the time of normal recording and reproduction, and is switched to the switch 9 at the time of a focus servo pull-in operation for starting recording and reproduction. And
The switch 9 is switched from the search signal generation circuit 8 to the focus servo circuit 7 at the same time as the focus servo loop is turned on.

The focus amplifier 10 drives the focus actuator of the two-axis actuator 25 based on the FE signal phase-compensated by the focus servo circuit 7 or the search signal generated by the search signal generation circuit 8 to reduce the focus error to zero. Objective lens 23
Is moved so that the focal position of the laser beam coincides with the recording layer of the optical disc D.

The system controller 11 controls data reproduction or recording by an RF signal processing unit (not shown) or the like, and controls processing of the entire apparatus such as interface control with an external apparatus.

Further, during the focus servo pull-in operation, the system controller 11 measures the signal level of the RF signal, switches the amplification factor of the RF amplifier 3, switches the switch 9 and switches the search signal generator circuit 8.
Control of the search signal that generates the error, detection of the zero point of the FE signal,
Processing such as ATIP signal detection is performed to determine whether the loaded optical disc D is a CD, a CD-R, or a CD-RW. As described above, in the optical disk drive device 1, a focus servo loop is formed by the optical pickup 2, the RF amplifier 3, the focus servo circuit 7, and the focus amplifier 10, and the focus position of the laser light emitted from the optical pickup 2 is determined. Match the recording surface. Also, in the optical disc drive device 1,
A tracking servo loop is formed by the optical pickup 2, the RF amplifier 3, the tracking servo circuit 4, and the tracking amplifier 5, so that the laser beam emitted from the optical pickup 2 can accurately follow the center position of the track of the optical disk D. Also, in the optical disc drive device 1,
When pulling in the focus servo, the optical disk D
The switching of the amplification factor of the RF amplifier 3 and the switching of the reproducing circuit and the recording circuit are performed.

Next, the contents of the focus servo pull-in process and the disc discrimination process performed at that time will be described with reference to the flowchart shown in FIG. 3 and the diagram showing the operation of the objective lens 23 shown in FIG.

When the optical disk D is loaded or the user or the like is instructed to start the recording operation or the reproducing operation, the system controller 11 of the optical disk drive device 1 performs the following focus servo pull-in processing from step S1. .

First, in step S1, the system controller 11 sets the amplification factor of the RF amplifier 3 to CD (CD
-R). That is, the amplification factor of the RF amplifier 3 is reduced so as to reproduce the optical disc D having a high reflectance.
Further, the system controller 11 switches the switch 9 to the search signal generation circuit 8 side.

Subsequently, in step S2, the system controller 11 causes the laser diode 21 of the optical pickup 2 to emit laser light. The laser power at this time is set to the reproduction level.

Subsequently, in step S3, the system controller 11 sends the search signal to the biaxial actuator 2
5 to bring the objective lens 23 closer to the optical disc D. Specifically, as shown in from time t ₁ in FIG. 4 to time t _2, the closer to the objective lens 23 on the optical disc D.

Subsequently, in step S4, the system controller 11 sends the search signal to the biaxial actuator 2
5 to move the objective lens 23 away from the optical disc D. Specifically, as shown at time t ₂ in FIG. 4, away from the position where the objective lens 23 is sufficiently close to the optical disc D, it will reduce the search signal to the objective lens 23 from the optical disc D. The position at time t ₂ when the objective lens 23 approaches the fully optical disc D is the position and the optical disk D objective lens 23 do not collide, S-shape of the RF signal to be detected is very small and the FE signal This is the position where the curve becomes the positive feedback area. In addition, the objective lens 23 may be provided with a separate distance detection mechanism with respect to the optical disk D to prevent collision.

Subsequently, in step S5, the system controller 11 determines whether or not the RF signal is higher than a predetermined level while the objective lens 23 is kept away from the optical disk D. That is, it is determined whether the optical disc D is loaded in the optical disc drive device 1 and reflected light is detected. If the RF signal does not exceed the predetermined level in step S5, the process proceeds to step S6, and if the RF signal exceeds the predetermined level, the process proceeds to step S8.

In step S6, the system controller 11 increments N, which is initially set to 0, by 1 and proceeds to step S7.
Determine if: If N is 3 or less, the processing from step S3 is repeated, and if N is more than 3, it is determined that the optical disk D is not loaded in the optical disk drive 1 (NO DISC).

In step S8, the system controller 11 measures the RF signal when the FE signal is near 0 level. Specifically, at time t _{3 in} FIG.
The RF signal is measured in the vicinity of the in-focus position where the focal position of the passing laser light shown in FIG. Then, the level of the RF signal at this time is set to the variable “LE”.
VEL ”.

Subsequently, in step S9, the system controller 11 determines whether or not "LEVEL" is equal to or higher than the determination level. This discrimination level is a threshold value provided for discriminating a CD (CD-R) and a CD-RW having different reflectances. That is, the RF amplifier 3
Is switched for CD (CD-R),
If the loaded optical disc D is a CD (CD-R), an appropriate level of RF signal is detected, but if the loaded optical disc D is a CD-RW, a sufficient level of R signal is detected.
No F signal is detected. Therefore, this discrimination level is set to CD
The type of the loaded optical disc D is determined by presetting based on the difference in reflectance between (CD-R) and CD-RW, and comparing this determination level with the level of the detected RF signal. be able to.

In step S9, if the system controller 11 determines that "LEVEL" is equal to or higher than the determination level, the system controller 11 determines that the loaded optical disk D is a CD or CD-R and repeats the processing from step S10. If it is determined that “LEVEL” is not higher than the determination level, the loaded optical disc D is
−RW and the processing from step S13 is performed.

In step S10, the system controller 11 supplies a search signal to the biaxial actuator 25 to bring the objective lens 23 closer to the optical disk D.
Specifically, the sufficiently away to the optical disc D objective lens 23 shown in time t ₄ in FIG. 4, it will increase the search signal closer to the objective lens 23 on the optical disc D. The position where the objective lens 23 is sufficiently far from the optical disc D is a position where the detected RF signal is very small and the S-shaped curve of the FE signal is in a positive feedback area.

Subsequently, in step S11, the system controller 11 turns on the focus servo loop when the RF signal is higher than a predetermined level and the FE signal is near 0 level. That is, the switch 9 is switched from the search signal generation circuit 8 side to the focus servo circuit 7 side. Specifically, at the position of the focus position near the recording surface of the focal position and the optical disk D of the laser beam passing through it is shown at time t ₅ in FIG. 4 are identical, turns on the focus servo loop.

By turning on the focus servo loop in step S11, the focus servo control is performed so that the objective lens 23 is located near the focal point thereafter.

Subsequently, in step S12, the system controller 11 detects the TE signal and determines whether or not the TE signal contains a synchronization signal of the wobble signal.

In step S12, the system controller 11 determines that the loaded optical disk D is a CD-R if the synchronization signal of the wobble signal is detected, and loads the synchronization disk if the synchronization signal of the wobble signal is not detected. It is determined that the optical disk D is a CD.

On the other hand, in step S13, the system controller 11 sets the amplification factor of the RF amplifier 3 to the CD-R
Switch for W. That is, the gain of the RF amplifier 3 is set so as to correspond to the optical disc D having a low reflectance by increasing the amplification factor.

Subsequently, in step S14, the system controller 11 supplies a search signal to the biaxial actuator 25 to bring the objective lens 23 closer to the optical disk D. Specifically, the objective lens 2 shown at time t ₄ in FIG. 4
3 increases the search signal from a position sufficiently distant from the optical disk D, and moves the objective lens 23 to the optical disk D.
Approach.

Subsequently, in step S15, the focus servo loop is turned on when the RF signal is higher than the predetermined level and the FE signal is near the 0 level. That is, the switch 9 is switched from the search signal generation circuit 8 side to the focus servo circuit 7 side. Specifically, at the position of the focus position near the recording surface of the focal position and the optical disk D of the laser beam passing through it is shown at time t ₅ in FIG. 4 are identical, turns on the focus servo loop.

Subsequently, in step S16, the system controller 11 detects the TE signal and determines whether or not the TE signal includes the synchronization signal of the wobble signal.

In step S16, the system controller 11 determines that the loaded optical disc D is a CD-RW if the synchronization signal of the wobble signal is detected, and re-determines if the synchronization signal of the wobble signal is not detected. The process from step S1 is repeated to perform the focus servo pull-in operation.

As described above, in the optical disk drive 1 according to the first embodiment of the present invention, the focus servo is pulled in and the CD, CD-R, CD-RW, NoD
isc can be determined. In particular, in the optical disk drive 1, the search operation at the time of pulling in can be minimized, and the optical disk D can be quickly and reliably determined.

In the optical disk drive 1, in performing the above-described processing from step S1 to step S16, the speed of the search operation in steps S3 and S4 and the speed of the search operation in steps S10 and S14 are changed to increase the speed. The pull-in operation of the focus servo can be completed. That is, the search operation for turning on the focus servo loop, that is, the search operation in steps S10 and S14, must be performed at a low speed so that the pull-in operation does not become unstable. The search operation in step S4 can be operated at high speed.

In the optical disk drive 1, R
The gain of the F-amplifier 3 is made variable so as to correspond to a plurality of optical discs D having different reflectances.
The laser power of the laser diode 21 may be made variable to support a plurality of optical discs D having different reflectivities.

In the optical disk drive 1, two types of optical disks D having different reflectivities have been described as an example.
By providing two or more preset thresholds as the determination level of 9, three or more types of optical discs D having different reflectivities can be determined.

Next, an optical disk drive according to a second embodiment of the present invention will be described with reference to the drawings.

In describing the optical disk drive of the second embodiment, the same components as those of the optical disk drive 1 of the first embodiment are designated by the same reference numerals in the drawings. A detailed description thereof will be omitted.

The optical disk drive of the second embodiment records and reproduces CDs, CD-Rs, and CD-RWs in the same manner as the optical disk drive 1 of the first embodiment. Is a single-layer read-only digital video disk (DVD-ROM (1
Layer)) and a playback-only digital video disk (DVD-ROM (two layers)) having two layers of signal surfaces. Here, CD etc. and DVD-ROM (one layer, two layers)
And the track pitch is different. While the track pitch of a CD or the like is 1.6 μm, the DVD-R
The track pitch of the OM (single layer, two layer) is 0.74 μm, and high density is achieved. DVD-ROM
The reflectivity of the (one layer) and that of the DVD-ROM (two layers) are different, and the reflectivity of the DVD-ROM (two layers) is low while the reflectivity of the DVD-ROM (one layer) is high. I have.

FIG. 5 shows a block diagram of an optical disk drive according to an embodiment of the present invention.

The optical disk drive device 31 stores a CD, C
An optical pickup (for CD) 2 that emits laser light to the DR and CD-RW and detects the reflected light, and a reproduction (RF) signal and a focus error ( RF amplifier (for CD) 3 for generating FE) signal, tracking error (TE) signal, etc.
A tracking servo circuit (for CD) 4 for performing predetermined phase compensation on the TE signal, and a two-axis actuator (for CD) 25 included in the optical pickup (for CD) 2 by amplifying the phase compensated TE signal. A tracking amplifier (for CD) 5 to be driven and a wobble signal demodulation circuit (for CD) 6 for demodulating a wobble signal included in the TE signal are provided.

Further, the optical disk drive device 31
A focus servo circuit (for CD) 7 for performing predetermined phase compensation on the E signal, a search signal generation circuit (for CD) 8 for generating a search signal for pulling in the focus servo,
A switch (for CD) 9 for switching between the search signal and the phase-compensated FE signal, and an optical pickup that amplifies the search signal or the phase-compensated FE signal that is supplied by being switched to the switch (for CD) 9 A focus amplifier (for CD) 10 that drives a two-axis actuator (for CD) 25 included in the (for CD) 2.

Further, the optical disk drive device 31
An optical pickup (for DVD) 32 for emitting a laser beam to a VD-ROM (one layer) and a DVD-ROM (two layers) and detecting the reflected light, and an optical pickup (DVD)
RF amplifier (for DVD) 33 that generates a reproduction (RF) signal, a focus error (FE) signal, a tracking error (TE) signal, etc. from the detection signal of 32) and a tracking servo that performs predetermined phase compensation on the TE signal Circuit (DV
D) 34, a tracking amplifier (for DVD) 35 that amplifies the phase-compensated TE signal to drive a two-axis actuator (for DVD) 55 of the optical pickup (for DVD) 32, and is included in the TE signal. And a wobble signal demodulation circuit (for DVD) 36 for demodulating the wobble signal.

Further, the optical disk drive device 31
A focus servo circuit (for DVD) 37 for performing predetermined phase compensation on the E signal, and a search signal generation circuit (for DVD) for generating a search signal for pulling in the focus servo
38, a switch (for DVD) 39 for switching between the search signal and the phase-compensated FE signal, and a switch (DV
D) 39 to amplify the search signal or the phase-compensated FE signal supplied thereto and amplify the search signal or the phase-compensated FE signal.
Amplifier (for DVD) 40 that drives 55)
And Also, the optical disk drive device 31
Are RF amplifier (for CD) 3 and RF amplifier (for DVD)
And a system controller 41 to which a RE signal, an FE signal, a wobble signal, and the like are supplied from the controller 33 to perform focus pull-in control and the like.

In the optical disk drive device 31 having such a configuration, the optical pickup 2 is used for a CD, CD-R, or CD.
The optical pickup 32 is used when recording or reproducing an RW, and includes a DVD-ROM (single layer) and a DVD-ROM.
It is used when recording / reproducing a ROM (two layers), and switching between them is controlled by the system controller 41.

The optical pickup 32 has a center wavelength of 65.
It has a laser diode 51 that emits 0 nm laser light. The optical pickup 32 irradiates the laser light emitted from the laser diode 51 onto a track of the optical disk D via an optical system including, for example, a polarization beam splitter 52 and an objective lens 53, and reflects the reflected light of the irradiated laser light to a photodetector. 54. The numerical aperture NA of the objective lens 53 is, for example, 0.6. Further, the optical pickup 32 has a biaxial actuator 55 for moving the objective lens 53 so that the laser beam irradiated on the optical disc D becomes just focus and just track.

The photodetector 54 of the optical pickup 32 detects the reflected light of the laser beam to generate a detection signal, and supplies the detection signal to the RF amplifier 33.

The RF amplifier 33 includes a photo detector 54
Is converted into a voltage value to generate an RF signal, an FE signal, a TE signal, and the like. In addition, this RF amplifier 33
Are RF signals and F signals according to the type of the optical disc D to be reproduced.
The amplification rates of the signal levels of the E signal and the TE signal are switched by a system controller 41 described later. That is, while a single-layer DVD-ROM has a high reflectance,
Since the reflectance of a two-layer DVD-ROM is low, if an RF signal or the like is generated at the same amplification rate on each disc, the DVD
When ROM (two layers) is reproduced, sufficient sensitivity cannot be obtained. Therefore, in the RF amplifier 33, DV
The sensitivity is adjusted by switching the amplification factor between the D-ROM (one layer) and the DVD-ROM (two layers).

The RF signal generated in this manner is represented by R
The signal is supplied from the F-amplifier 33 to an RF signal processing unit (not shown) and the like.
The data is subjected to error correction processing and the like, and is supplied to an external device via an interface. The RF signal is also supplied to the system controller 41.

The FE signal is supplied from the RF amplifier 33 to the focus servo circuit 37 and the system controller 41. The TE signal is supplied from the RF amplifier 33 to the tracking servo circuit 34, the wobble signal demodulation circuit 36, and the system controller 41.

The tracking servo circuit 34 is provided with a disturbance irrelevant to the tracking servo loop control, for example,
While removing wobble signal components and data components,
Dispersion caused by eccentricity of rotation of the optical disk or the like is absorbed, and phase compensation is performed so as to gain open loop servo gain in a low frequency range.

The tracking amplifier 35 drives the tracking actuator of the biaxial actuator 55 based on the phase-compensated TE signal, moves the objective lens 53 so that the tracking error becomes zero, and irradiates the optical disk D. Control is performed so that the laser spot follows the center of the track.

The wobble signal demodulation circuit 36 detects a wobble signal included in the high frequency of the TE signal, and detects an ATIP signal recorded as the wobble signal.

The focus servo circuit 37 performs phase compensation of the FE signal so as to remove disturbances unrelated to the focus servo loop control, for example, data components, and supplies the FE signal to the focus amplifier 40 via the switch 39. I do.

The search signal generating circuit 38 generates a search signal to be supplied to the focus actuator of the biaxial actuator 55 at the time of the focus servo pull-in operation. When this search signal is supplied via the focus amplifier 40, the biaxial actuator 55
3 is moved up and down within the movable range.

The switch 39 is connected to the system controller 4
The switching is controlled by 1 and the FE signal whose phase is compensated by the focus servo circuit 37 and the search signal generated by the search signal generation circuit 38 are switched and supplied to the focus amplifier 40. The switch 39 is switched to the focus servo circuit 37 during normal recording and reproduction, and is switched to the switch 39 during focus servo pull-in operation for starting recording and reproduction. The switch 39 is switched from the search signal generation circuit 38 to the focus servo circuit 37 at the same time as the focus servo loop is turned on.

The focus amplifier 40 is based on the FE signal phase-compensated by the focus servo circuit 37 or the search signal generated from the search signal generation circuit 38.
The focus actuator of the two-axis actuator 55 is driven, the objective lens 53 is moved so that the focus error becomes zero, and control is performed so that the focal position of the laser beam coincides with the recording layer of the optical disc D.

The system controller 41 controls data reproduction or recording by an RF signal processing unit (not shown) or the like, and controls processing of the entire apparatus such as interface control with an external apparatus.

The system controller 41 determines whether the loaded optical disk D is a CD, a CD-R, a CD-RW, or a DVD-ROM (1
Layer) or a DVD-ROM (two layers).

The system controller 41 selects a circuit to be used based on the result of the determination of the type of the optical disc D. That is, the system controller 41
The loaded optical disk D is a CD, CD-R, CD-
In the case of RW, the optical pickup 2, RF amplifier 3, tracking servo circuit 4, tracking amplifier 5, wobble signal demodulation circuit 6, focus servo circuit 7
And the like to control the recording or reproduction of data,
The loaded optical disk D is a DVD-ROM (single layer)
Alternatively, in the case of a DVD-ROM (two layers), control of data reproduction is performed using the optical pickup 32, RF amplifier 33, tracking servo circuit 34, tracking amplifier 35, wobble signal demodulation circuit 36, focus servo circuit 37, and the like. Do.

Next, the optical disk drive 31
The content of the focusing servo pull-in process and the disc discrimination process performed at that time will be described with reference to the flowchart shown in FIG.

The system controller 41 of the optical disk drive device 31 loads the optical disk D or
When a user or the like is instructed to start a recording operation or a reproduction operation,
The focus servo pull-in process shown in the following step S21 is performed.

In discriminating a disc, the optical disc drive device 31 first performs a CD (CD-R, CD-R
The circuit for W) is selected, and a focus servo pull-in operation is performed.

First, in step S21, the system controller 41 switches the amplification factor of the RF amplifier 3 for CD to that for CD (CD-R). That is, the RF amplifier 3 for CD is designed to reproduce the optical disk D having a high reflectance.
Decrease the amplification factor. Also, the system controller 41
Switches the switch 9 for CD to the search signal generating circuit 8 side.

Subsequently, in step S22, the system controller 41 causes the laser diode 21 of the optical pickup 2 for CD to emit laser light. The laser power at this time is set to the reproduction level.

Subsequently, in step S23, the system controller 41 supplies a search signal to the biaxial actuator 25 to bring the objective lens 23 of the optical pickup 2 for CD closer to the optical disk D.

Subsequently, in step S24, the system controller 41 supplies a search signal to the biaxial actuator 25 to move the objective lens 23 away from the optical disk D. At this time, the system controller 41 drives the tracking actuator of the biaxial actuator 25 to move the objective lens 23 closer to the optical disk D while shaking it in the radial direction. For example, the system controller 41 outputs a sine wave signal having a relatively small amplitude from the tracking amplifier 5 and sets the objective lens 23 to the optical disk D.
And reciprocate in the radial direction.

Subsequently, in step S25, the system controller 41 determines whether or not the RF signal is higher than a predetermined level while the objective lens 23 is kept away from the optical disc D. That is, it is determined whether the optical disk D is loaded in the optical disk drive device 31 and the reflected light is detected. If the RF signal does not exceed the predetermined level in step S25, step S2
The process proceeds to step S6, and when the RF signal is higher than the predetermined level, the process proceeds to step S28.

In step S26, the system controller 41 increments N, which is initially set to 0, by 1 and proceeds to step S27, and determines in step S27 whether N is 3 or less. If N is 3 or less, the processing from step S23 is repeated, and if N is more than 3, it is determined that the optical disk D is not loaded in the optical disk drive 31 (NO DISC).

In step S28, the system controller 41 measures the RF signal when the FE signal is near the 0 level, that is, near the focal point where the focal position of the laser beam coincides with the recording surface of the optical disk D. I do. The level of the RF signal at this time is set as a variable LEVEL. In step S28, the system controller 41 detects a tracking error signal called a traverse signal generated when the laser light reciprocates in the radial direction of the optical disk D and crosses the track.

Subsequently, in step S29, the system controller 41 determines whether or not this variable "LEVEL" is equal to or higher than the determination level. This discrimination level is used to discriminate between CDs (CD-R) and CD-RWs having different reflectances, or between DVD-ROM (single layer) and DV.
This is a threshold value provided for discriminating a D-ROM (two layers). That is, the amplification factor of the RF amplifier 3 is set to CD (CD
−R), an appropriate level of RF signal is detected if the loaded optical disc D is a CD (CD-R) or a DVD-ROM (single layer). D is CD-RW or DVD-ROM
If it is (two layers), a sufficient level of RF signal is not detected. Therefore, this discrimination level is set to CD (CD-R) and CD (CD-R).
-RW or DVD-ROM (single layer) and DVD-R
The type of the loaded optical disc D can be determined by presetting based on the difference in reflectance from the OM (two layers) and comparing this determination level with the level of the detected RF signal. In this step S29, if the system controller 41 determines that "LEVEL" is equal to or higher than the determination level, the system controller 41 determines that the loaded optical disk D is a CD, CD-R or DVD-ROM (single layer) and proceeds to step S30. Process from
If it is determined that “LEVEL” is not equal to or higher than the determination level, the loaded optical disc D
The processing from step S34 is performed on the assumption that the VD-ROM is a two-layer VD-ROM.

In step S30, the system controller 41 determines whether a traverse signal has been detected and determines whether the loaded optical disc D is a CD (CD-R).
Or a DVD-ROM (single layer).

That is, since the pickup used in this series of processing is the optical pickup 2 for CD, the center wavelength of the laser light emitted from the laser diode 21 is 780 nm, The numerical aperture NA of the lens 23 is 0.45. Therefore, a DVD-RO having a track pitch of 0.74 μm
In M (one layer) or DVD-ROM (two layers), a tracking error signal cannot be detected. Therefore, by detecting a traverse signal generated when the objective lens 23 is reciprocated in the radial direction of the optical disc D,
The loaded optical disk D is a CD (CD-R, CD-R
W) or a DVD-ROM (single layer, double layer).

If it is determined in step S30 that no traverse signal is detected, it is determined that the loaded optical disk D is a DVD-ROM (single layer). Then, the system controller 41 sets each circuit to be used to D
While switching to the VD circuit, the amplification factor of the RF amplifier 33 is switched to that for the DVD-ROM (single layer), and the focus servo pull-in operation is performed.

If a traverse signal is detected in step S30, the process proceeds to step S31.

Subsequently, in step S31, the system controller 41 supplies a search signal to the biaxial actuator 25 to bring the objective lens 23 closer to the optical disc D.

Subsequently, in step S32, the system controller 41 determines that the RF signal is higher than the predetermined level and the FE signal is near the 0 level, ie,
The focus servo loop is turned on near the focal point where the focal position of the laser beam coincides with the recording surface of the optical disk D.

In this step S32, by turning on the focus servo loop, the focus servo control is performed so that the objective lens 23 is located near the focal point thereafter.

Subsequently, in step S33, the system controller 41 detects the TE signal and determines whether or not the TE signal includes the synchronization signal of the wobble signal.

In this step S33, the system controller 41 determines that the loaded optical disk D is a CD-R if the synchronization signal of the wobble signal is detected, and determines that the loaded optical disk D is the CD-R if the synchronization signal of the wobble signal is not detected. It is determined that the optical disk D is a CD.

On the other hand, in step S34, it is determined whether a traverse signal has been detected, as in step S30 described above. If it is determined that no traverse signal is detected, the loaded optical disc D is
OM (two layers) is determined. Then, the system controller 41 switches each circuit to be used to the circuit for DVD, and sets the amplification factor of the RF amplifier 33 to the DVD-
Switching to the ROM (two layers) is performed, and the focus servo pull-in operation is performed.

If a traverse signal is detected in step S34, the process proceeds to step S35.

Subsequently, in step S35, the system controller 41 sets the amplification factor of the RF amplifier 3 to the CD-R
Switch for W. That is, the gain of the RF amplifier 3 is set so as to correspond to the optical disc D having a low reflectance by increasing the amplification factor.

Subsequently, in step S36, the system controller 41 supplies a search signal to the biaxial actuator 25 to bring the objective lens 23 closer to the optical disc D.

Subsequently, in step S37, when the RF signal is higher than the predetermined level and the FE signal is near the 0 level, that is, when the focal position of the laser beam and the recording surface of the optical disc D coincide with each other, Turn on the focus servo loop at position.

Subsequently, in step S38, the system controller 41 detects the TE signal, and determines whether or not the TE signal contains the synchronization signal of the wobble signal.

In this step S38, the system controller 41 determines that the loaded optical disk D is a CD-RW if the synchronization signal of the wobble signal is detected, and if the synchronization signal of the wobble signal is not detected, the system controller 41 again. The processing from step S21 is repeated to perform the focus servo pull-in operation.

As described above, in the optical disk drive device 31 according to the second embodiment of the present invention, the focus servo is pulled in and the CD, CD-R, CD-RW, DV
D-ROM (one layer), DVD-ROM (two layers), NoD
isc can be determined. In particular, the optical disc drive device 31 can discriminate a plurality of discs having different reflectances and also discriminate a plurality of discs having different track pitches.

[0120]

In the optical disk apparatus according to the present invention, the objective lens is moved away from the optical disk, and the reproduction is performed in the vicinity of the position of the objective lens where the reproduction signal is above a predetermined level and the focus error signal becomes zero. The reflectivity of the optical disc is determined by detecting the signal level, the objective lens is moved closer to the optical disc, and the pull-in operation of the focus servo control is performed.

As a result, in the optical disk apparatus according to the present invention, it is possible to quickly and surely determine the optical disks having different reflectances and to quickly and surely pull in the focus servo.

Further, in the focus servo pull-in method according to the present invention, the objective lens is moved away from the optical disk, and the reproduction signal is at a predetermined level or higher and the focus error signal becomes zero near the position of the objective lens. Then, the level of the reproduced signal is detected to determine the reflectivity of the optical disk, and the objective lens is moved closer to the optical disk to start the focus servo control.

As a result, discrimination of optical disks having different reflectivities can be performed quickly and reliably, and the focus servo can be quickly and reliably drawn.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disk drive device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a photodetector of an optical pickup of the optical disc drive device according to the first embodiment.

FIG. 3 is a flowchart showing processing contents of the optical disk drive device of the first embodiment.

FIG. 4 is a diagram for explaining the operation of an objective lens of the optical pickup of the optical disk drive device according to the first embodiment.

FIG. 5 is a block diagram of an optical disk drive according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing processing contents of the optical disk drive device according to the second embodiment.

[Explanation of symbols]

1 optical disk drive device, 2 optical pickup,
3 RF amplifier, 4 tracking servo circuit, 5 tracking amplifier, 6 wobble signal demodulation circuit, 7 focus servo circuit, 8 search signal generation circuit, 9 switch, 10 focus amplifier, 11 system controller, 21 laser diode, 23 objective lens, 2
4 Photodetector, 25 2-axis actuator

Claims (2)

[Claims] 1. A first optical disc and a second optical disc having different reflectivities.
An optical disc device that performs recording and / or reproduction corresponding to an optical disc, has an objective lens for condensing laser light, emits laser light through the objective lens, detects reflected light, and detects the reflected light. An optical pickup that outputs a detection signal according to the optical pickup, and based on the detection signal of the optical pickup, a reproduction signal of the optical disk, and an error between a focus position of the laser light emitted from the optical pickup and a recording surface of the optical disk. And an amplification factor is set according to the first optical disc having a low reflectance and the second optical disc having a high reflectance, and the generated reproduction signal and focus error signal are generated at the set amplification factor. Generating and amplifying means for amplifying and outputting, and a laser for an objective lens of the optical pickup based on the focus error signal. Focus servo control for moving the focus position of the laser beam to the position on the recording surface of the optical disc by moving the focus servo control, and focus servo means for performing pull-in control of the focus servo control. Moving the objective lens away from the optical disc after bringing the objective lens sufficiently close to the optical disc, and in the vicinity of the position of the objective lens where the reproduction signal is above a predetermined level and the focus error signal becomes zero, And if the detected level of the reproduced signal is lower than a predetermined threshold, the amplification factor of the generating / amplifying means is set to an amplification factor corresponding to the first optical disk, and the level of the detected reproduced signal is set. Is higher than a predetermined threshold value, the amplification factor of the generation / amplification means is changed to the amplification factor corresponding to the second optical disc. After moving the objective lens sufficiently far from the optical disc, move the objective lens closer to the optical disc, and perform the focus servo control near the position where the reproduction signal is equal to or higher than a predetermined level and the focus error signal becomes zero. An optical disk device for performing pull-in control of the focus servo control for starting the operation. 2. A reproduction signal of an optical disk and a focus error signal generated from a detection signal of an optical pickup are converted into a first optical disk having a low reflectance and a second optical disk having a high reflectance.
A focus servo pull-in method for performing recording and / or reproduction corresponding to the first optical disc and the second optical disc having different reflectivities by amplifying at an amplification factor according to the optical disc of the present invention. After moving the objective lens sufficiently close to the optical disk, the objective lens is moved away from the optical disk, and the level of the reproduction signal is near the position of the objective lens where the reproduction signal is above a predetermined level and the focus error signal becomes zero. And when the level of the detected reproduction signal is lower than a predetermined threshold, the amplification factor is set to the amplification factor corresponding to the first optical disc,
If the level of the detected reproduction signal is higher than a predetermined threshold, the gain is set to the amplification factor corresponding to the second optical disk, and the objective lens is moved sufficiently away from the optical disk before moving the objective lens closer to the optical disk. A focus servo control method, wherein the focus servo control is started near a position where the reproduction signal is equal to or higher than a predetermined level and the focus error signal becomes zero.