JPH11306555A - Signal processor, servo signal processor and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a signal processor, a servo signal generator and a disk device which independently operate under optimum conditions for recording, reproducing and servo control operations. SOLUTION: The recording and reproducing of information are conducted by irradiating an optical disk 17 with laser spots on the optical disk device. An optical pickup 1 is provided with first laser light beams having a first wavelength λ1 and second laser light beams having a second wavelength λ2 which is longer than the wavelength λ1. The pickup 1 forms a laser spot by the first laser beams and a laser spot by the second laser beams on the disk 17. The returning light beams of the first laser light beams from the disk 17 are used for a recording and a reproducing. The returning light beams of the second laser beams from the disk 17 are used for the servo control of the pickup 1. Thus, an optimum reproducing condition and a servo optimum condition are satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing device, a servo signal generating device, and a disk device, for example, reproducing a video recorded on a compact disk (CD) or a digital video disk (DVD) as a disk-shaped recording medium. Can be applied to a disk device that performs the following.

[0002]

2. Description of the Related Art Conventionally, in an optical disk apparatus for recording information on an optical disk or reproducing information recorded on the optical disk, an optical pickup is positioned with respect to the optical disk to reproduce the information. In this case, a tracking error signal is generated separately from the reproduction signal, and positioning in the cross-track direction is performed using the tracking error signal.

FIG. 6 shows detection of a conventional tracking error signal and a reproduction signal. In FIG. 6, a laser beam is transmitted from a laser diode (not shown) to an optical disk 6.
0 is radiated through the objective lens 63. Optical disk 60
Has a groove 6 in which information is recorded at a track pitch 61.
1 is formed. The return light from the optical disk 60 passes through the objective lens 63. At this time, the zero-order diffracted light 65 without diffraction and the first-order diffracted lights 64 and 64 ′ are generated by the diffraction of the laser beam in the groove 61 in the cross-track direction.

[0004] An objective lens 63 is provided with a 0th-order diffracted light 65 and a 1st-order diffracted light.
A part 66 overlapping the zero-order diffracted light 65 in a part of the diffracted lights 64 and 64 ′ passes. After passing through this objective lens 63,
The zero-order diffracted light 65 and a part of the first-order diffracted lights 64 and 64 ′
A portion 66 overlapping the next diffracted light 65 is detected by a detector 67 that is a two-segment photodiode (2D-PD).
The addition value of the two-divided light receiving unit from the detector 67 is amplified and output from the reproduction amplifier 69 as a reproduction signal (B). Further, the subtraction value of the two-divided light receiving unit from the detector 67 is amplified and output from the comparator 68 as a tracking error signal (A).

FIG. 7 is a diagram showing characteristics of a conventional tracking error signal and the amount of reflected light. Here, λ is the wavelength of the laser beam emitted from the laser diode, and n is the refractive index of the substrate of the optical disk. As shown in FIG.
When the guide groove depth (λ / n) = λ / 8n shown on the horizontal axis, the relative value shown on the vertical axis is 1.0.
The reflection light amount 71 is the largest when compared with the relative value 0 of the land portion where the guide groove depth (λ / n) = 0, but the reflected light amount 71 is the guide groove depth (λ / n) = λ / 4n shown on the horizontal axis. At this time, the relative value shown on the vertical axis becomes 0, which is the maximum when compared with the relative value 1.0 of the land portion where the guide groove depth (λ / n) = 0. In FIG. 7, when the depth of the guide groove (λ / n) = λ / 4n in the amount of reflected light 71, the optimum reproduction condition is shown.
The servo optimum conditions are shown when the guide groove depth (λ / n) = λ / 8n in FIG. n indicates the refractive index of the substrate.

However, since the reproduction signal and the tracking error signal are separated by adding and subtracting the return light on the detector using a single laser diode, the optimum reproduction condition and the optimum servo condition are not matched. Without
Guide groove depth (λ / n) = λ /
At 6n, the depth of the pit or groove was determined.

Japanese Patent Application Laid-Open No. 7-311945 discloses a first optical head adapted to both first and second optical recording media having different thicknesses, and a first optical head adapted only to the first optical recording medium. An optical recording / reproducing apparatus has been disclosed which is capable of using a low-power light source by providing two optical heads and reducing an optical burden for compatibility between media having different substrate thicknesses. I have.

[0008]

However, in the above-mentioned conventional disk drive, the depth of the pit or groove is determined at a position deviating from the optimum reproduction condition and the optimum servo condition. However, there is an inconvenience that it is difficult to increase the density, and the stability of the servo is impaired.

The optical recording / reproducing apparatus described in Japanese Patent Application Laid-Open No. 7-311945 only discloses that two optical heads are provided, and the above-mentioned problem cannot be solved.

The present invention has been made in view of the above points, and a signal processing device, a servo signal generation device, and an optical disk device capable of independently operating under optimum conditions for recording / reproduction and servo control. It is intended to propose.

[0011]

According to the present invention, there is provided a signal processing apparatus for recording information by forming pits on an optical disc or by irradiating a laser spot on a groove. A signal processing device for performing signal processing for reproducing information recorded in the pits or grooves by irradiating the first laser light with a first laser light having a first wavelength and a first laser light having a first wavelength. Forming a laser spot by the first laser beam and a laser spot by the second laser beam on the optical disc using an optical pickup having a second laser beam having a second wavelength that is also long. The return light of the first laser light from the optical disk is used for recording and reproducing information, and the optical data of the second laser light is The return light from the disk is obtained as used in servo control of the optical pickup.

Further, the servo signal processing apparatus of the present invention records information by positioning an optical pickup on an optical disk by a servo signal and forming pits or irradiating a laser spot on a groove,
A servo signal processing device for performing servo signal processing for reproducing information recorded in the pits or the grooves by irradiating the optical disk with a laser beam; a first laser beam of a first wavelength; Using an optical pickup having a second laser beam of a second wavelength longer than the first wavelength, the first
Forming a laser spot by the second laser light and a laser spot by the second laser light;
The laser light returned from the optical disc is used for recording and reproducing information, and the laser light returned from the optical disc is used for at least positioning servo control of the optical pickup.

The optical disk apparatus of the present invention records information by positioning an optical pickup on an optical disk and forming pits or irradiating a laser spot on a groove, and irradiating a laser beam on the optical disk. In an optical disk device for reproducing information recorded in the pits or grooves by irradiating, a first laser beam of a first wavelength and a second laser beam of a second wavelength longer than the first wavelength Using an optical pickup having light, the first
Forming a laser spot by the second laser light and a laser spot by the second laser light;
The laser light returned from the optical disc is used for recording and reproducing information, and the laser light returned from the optical disc is used for at least positioning servo control of the optical pickup.

According to the optical disk device of the present invention, the following operations are performed. In the first optical system, a first laser beam having a first wavelength is emitted, the emitted first laser beam is converted into a parallel beam, emitted to an optical disc via an objective lens, and returned light is collected. The illuminated and collected return light is detected. Further, in the second optical system, a second laser light having a second wavelength longer than the first wavelength is emitted, and the emitted second laser light is converted into parallel light, which is transmitted through an objective lens. The optical disk is irradiated, the return light is collected, and the collected return light is detected. In addition, the objective lens forms the light spot on the optical disc by condensing the first laser light and the second laser light in common with the first optical system and the second optical system.

In the optical pickup, the objective lens is independently moved by a biaxial actuator in a focus direction (a direction approaching or separating from the optical disk) and a tracking direction (a direction crossing a track of the optical disk).

Thus, while the optical disk is being driven to rotate, the first and second laser beams are radiated to the spirally formed track by the movement of the optical pickup.
The return lights are individually and independently detected, and the first detection signal is amplified by a reproduction amplifier and processed as a reproduction signal.
Further, the second detection signal is subtracted and processed as a focus signal and a tracking signal, respectively.

Since a shorter laser wavelength is more suitable for increasing the recording density, a first laser beam having a relatively short laser wavelength is used for recording and reproduction, and a second laser beam having a relatively long laser wavelength is used for servo. . For the second laser beam having a relatively long laser wavelength, the tracking error signal is set so that the tracking error signal becomes maximum as compared with the relative value of the land portion. Is obtained. In addition, for the first laser light having a relatively short laser wavelength, the laser wavelength is set so that the amount of reflected light becomes maximum as compared with the relative value of the land portion. Can be obtained, thereby enabling high density.

As described above, the first laser beam having a relatively short laser wavelength is set so that the guide groove depth in the reflected light amount becomes the optimum reproduction condition, and the guide groove depth in the tracking error signal is set to the servo optimum condition. Since the second laser beam whose laser wavelength is relatively long is set so that
The reproduction signal of the optimal reproduction condition is detected by the reflected return light of the first laser beam from the optical disk obtained from the optical pickup, and the focus error of the servo optimal condition is detected by the reflected return light of the second laser light from the optical disk. A signal and a tracking error signal are generated. Then, an actuator coil in the optical pickup is driven based on the focus error signal and the tracking error signal, and tracking and focusing of the optical pickup are performed to reproduce a reproduction signal.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disc device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG.
FIG. 1 is a diagram showing a configuration of an optical pickup according to an embodiment of the present invention. The optical pickup according to the embodiment of the present invention is applied to an optical disk device.

That is, the optical pickup 1 has a first optical system for detecting a reproduced signal and a second optical system for detecting a servo signal. First, the first optical system will be described. In FIG. 1, a first optical system includes a laser diode (LD1) 2 for emitting a first laser beam having a wavelength λ1, a collimator lens 3 for converting the first laser beam into parallel light, and a first laser beam. A polarizing beam splitter (BPS1) 4 that transmits the parallel light and reflects the return light by 90 degrees;
Polarizing beam splitter (BPS1) 4 9
A condenser lens 7 for condensing the 0-degree reflected return light, and a detector (1) for detecting the return light collected by the condenser lens 7
8 is provided.

The second optical system includes a laser diode (LD2) 9 for emitting a second laser beam having a wavelength λ2 longer than the wavelength λ1, a collimator lens 10 for converting the second laser beam into parallel light, and the like. A polarizing beam splitter (BPS2) 11 which transmits parallel light of the second laser beam and reflects return light by 90 degrees.
And Polarizing Beam Splitter (BPS2) 1
Condensing lens 12 for condensing return light reflected by 90 degrees at 1
And a detector (2) 13 for detecting the return light collected by the condenser lens 12.

The optical pickup 1 is used in common with the first optical system and the second optical system. The optical pickup 1 transmits the polarized beam splitter (BPS1) 4 transmitted from the first optical system. The parallel light of the first laser beam is reflected at 90 degrees and the return light is reflected at 90 degrees, and the parallel light of the second laser beam transmitted through the polarizing beam splitter (BPS2) 11 from the second optical system is transmitted. A wavelength selection element 5 for transmitting the return light, and an objective lens 6 for condensing the first laser beam and the second laser beam reflected or transmitted by the wavelength selection element 5 to form a light spot on the optical disc 17 Have.

In the optical pickup 1, the objective lens 6 has a focus direction (a direction approaching or separating from the optical disk 17) and a tracking direction (a direction crossing a track of the optical disk 17) by a biaxial actuator using an electromagnetic force. Will be moved independently.

The optical pickup 1 is sequentially moved in the outer peripheral direction of the optical disk 17 by a slide motor (not shown) in synchronization with the rotation of the optical disk 17, thereby sequentially irradiating the laser beam with the laser beam.
7 in the outer peripheral direction.

Thus, while the optical disk 17 is driven to rotate, the first and second laser beams are irradiated on the spirally formed track by the movement of the optical pickup 1, and the returned light is detected by the detector (1). 8 and the detector (2) 13 detect each signal independently, and the detection signal of the detector (1) 8 is amplified by the reproduction amplifier 14 and supplied to the RF circuit (not shown) as the reproduction signal (C). Further, the two-divided detection signal of the detector (2) 13 is subtracted by an operational amplifier 15 and an operational amplifier 16 and supplied to a servo error generating circuit (not shown) as a focus signal (E) and a tracking signal (D), respectively.

The RF circuit generates a reproduced RF signal from the detection signal, and the servo error generating circuit generates a servo error signal. The reproduced RF signal is demodulated, an error correction code is detected and error correction is performed, and then deinterleaving and EFM-PLUS demodulation are performed. Then, the reproduction signal is supplied to the output amplifier. The output amplifier amplifies the signal to an outputable level and outputs the signal.

In this embodiment, since the shorter laser wavelength is suitable for higher recording density, the first laser beam of λ1 whose laser wavelength is relatively short is used for recording and reproduction, and the laser wavelength is shorter. A relatively long second laser beam of λ2 is used for servo.

Specifically, when the laser wavelength is relatively long λ
7, the tracking error signal 70 has a relative value shown on the vertical axis when the guide groove depth (λ / n) = λ / 8n shown on the horizontal axis, as shown in FIG. 1.
Since the laser wavelength λ2 is set so as to be 0 and becomes maximum as compared with the relative value 0 of the land portion where the guide groove depth (λ / n) = 0, a tracking error signal having a high S / N can be obtained.

For the first laser beam having a relatively short laser wavelength of λ1, as shown in FIG. 7, the amount of reflected light 71 is equal to the guide groove depth (λ / n) = λ / n shown on the horizontal axis. 4
When n, the relative value shown on the vertical axis becomes 0, and the depth of the guide groove (λ /
n) Since the laser wavelength λ1 is set so as to be maximum as compared with the relative value 1.0 of the land portion at 0, a high S /
N recording / reproducing signals can be obtained, thereby enabling higher density.

As described above, in FIG.
The first laser beam of λ1 having a relatively short laser wavelength is set so as to satisfy the optimum reproduction condition of the guide groove depth (λ / n) = λ / 4n in the tracking error signal 70.
The laser wavelength is relatively long so that the servo optimum condition of guide groove depth (λ / n) = λ / 8n
Optical pickup 1
The reproduction signal of the optimal reproduction condition is detected by the reflected return light of the first laser beam obtained from the optical disk 17, and the focus error of the servo optimal condition is detected by the reflected return light of the second laser beam from the optical disk 17. A signal and a tracking error signal are generated. Then, an actuator coil in the optical pickup 1 is driven based on the focus error signal and the tracking error signal, and tracking and focusing of the optical pickup 1 are performed to reproduce a reproduction signal.

FIG. 2 shows a configuration diagram of another optical pickup according to the present embodiment. The other optical pickup 20 shown in FIG. 2 is different from the optical pickup 1 shown in FIG. 1 in that the wavelength selection element 5 is not provided, the first laser beam objective lens of the first optical system, and the second optical pickup. The point is that objective lenses 21 and 22 for the second laser beam of the system are separately provided. 2, components corresponding to those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the optical pickup 1 shown in FIG.
Since two objective lenses 6 handle laser beams of two wavelengths λ1 and λ2, an objective lens having no chromatic aberration for any wavelength must be used. On the contrary,
The other optical pickup 20 shown in FIG. 2 combines two objective lenses 21 and 22 having no chromatic aberration with respect to these two wavelengths λ1 and λ2, respectively, to form a first optical system and a second optical system.
In the path of the first laser beam and the second laser beam of the optical system.

In the optical pickup 20,
The objective lenses 21 and 22 are independently moved by a two-axis actuator using an electromagnetic force in a focus direction (a direction approaching or separating from the optical disk 17) and a tracking direction (a direction crossing tracks of the optical disk 17).

The optical pickup 20 is sequentially moved in the outer peripheral direction of the optical disk 17 by a slide motor (not shown) in synchronization with the rotation of the optical disk 17, whereby the irradiation position of the laser beam is sequentially moved in the outer peripheral direction of the optical disk 17. Displace.

Thus, while the optical disk 17 is being driven to rotate, the first and second laser beams are irradiated on the spirally formed track by the movement of the optical pickup 20, and the returned light is detected by the detector (1). 8 and the detector (2) 13 are detected separately and independently.
The detection signal of the detector (1) 8 is amplified by the reproduction amplifier 14 and supplied to the RF circuit (not shown) as the reproduction signal (F). The two-divided detection signal of the detector (2) 13 is subtracted by the operational amplifier 15 and the operational amplifier 16 and supplied to a servo error generating circuit (not shown) as a focus signal (H) and a tracking signal (G), respectively.

FIG. 3 shows the formation of a spot according to the present embodiment described above. Another optical pickup 20 shown in FIG.
Since the objective lens 21 and the objective lens 22 are combined, the tracking servo and the focus servo can be performed by the tracking coil and the focus coil of the same two-axis actuator. In FIG.
When tracking control is performed on the groove 31 between the lands 30 and 32, the spot 33 formed by the LD2 and the spot 34 formed by the LD1 are both adjusted to be formed on the groove 31. At this time, the spot 33 made by the long wavelength LD2 is changed to the spot 34 made by the short wavelength LD1.
Larger than. Further, the focus of the two spots 33 and 34 is adjusted so as to be focused at the same distance.
Although not shown, the spot formed by the optical pickup 1 shown in FIG. 1 includes, for example, a spot 34 formed by the LD 1 and a spot 33 formed by the LD 2 concentrically on the groove 31 in FIG.

In the case of a read-only optical disk such as a CD-ROM or a DVD-ROM, tracking servo is performed using pits on which tracking address information is recorded. In the case of (1), tracking is performed using a groove in which address information for tracking is recorded.
In the above-described spot formation, the same operation is performed in any case.

Next, the operation of the optical disk apparatus according to the present embodiment when the objective lens is moved by a two-axis actuator to a target track, called a seek operation, will be described. FIG. 4 is a diagram illustrating a moving direction detecting method according to the present embodiment, and FIG. 5 is a block diagram illustrating a configuration of an optical disc device according to the present embodiment.

In FIG. 5, the optical disk device of the present embodiment has a spindle motor 51 for rotating the optical disk 50 and an objective lens 52 moved in a track cross direction and a focus direction by a two-axis actuator.
Alternatively, the optical pickup 53 shown in FIG. 2, a reproduction signal processing circuit 54 that reproduces an information signal by processing a reproduction signal (C) from the optical pickup 53, and a reproduction signal (C) from the optical pickup 53 And a seek direction detecting circuit 55 for detecting a seek direction using the tracking error signal (D), and a tracking error signal (D) and a focus error signal (E) from the optical pickup 53 and a direction from the seek direction detecting circuit 55. The servo signal processing is performed using the signal (DER) and the focus signal (SF), the tracking signal (ST), and the actuator drive signal (SD) are sent to the optical pickup 53.
And a servo processing circuit 56 for supplying Although not shown, a system controller for controlling the optical disk device is provided. The optical pickup 5
Reference numeral 3 corresponds to the optical pickup 1 or 20 shown in FIG. 1 or FIG. 2, and the objective lens 52 corresponds to the objective lens 6 or 21 and 22 shown in FIG. 1 or FIG.

The seek operation will be described below. When a seek operation is started in a state where the spindle motor 51 is rotated, a focus signal (SF), a tracking signal (ST), and an actuator drive signal (SD) are sent from the servo processing circuit 56 to the optical pickup 53 based on a command from the system controller. Is supplied. The objective lens 52 is moved in the cross-track direction by the biaxial actuator of the optical pickup 53.

At this time, as shown in FIG. 4A, the reproduced signal (C) includes a traverse signal (also called a track cross signal) in addition to the high frequency signal. The traverse signal is a continuous sinusoidal signal when the light spot moves in the cross-track direction because the diffracted light from the groove or the pit leaks into a portion other than the adjacent land or the adjacent pit.

This traverse signal appears most remarkably in the highest detection state when the pit or groove depth is close to λ / 4n, and becomes lowest when the pit or groove depth is λ / 8n. The traverse signal is a signal necessary for the seek operation, and the amplitude of the traverse signal also changes depending on the ratio of the width of the land to the groove in the radial direction. However, according to the optical disk device of the present embodiment described above, , A traverse signal having a sufficient amplitude can be obtained from the reproduction signal (C).

Referring to FIG. 4, how a traverse signal is used during a seek will be described. In the seek direction detection circuit 55 shown in FIG. 5, the phases of the reproduction signal (C) and the tracking error signal (D) shown in FIG. 4A are compared. Specifically, as shown in FIG. 4, when the light spot accompanying the movement of the objective lens is moving in the outer peripheral direction,
Although the tracking error signal shown in FIG. 4B has a leading phase with respect to the reproduction signal shown in FIG. 4A, when the light spot is moving in the inner circumferential direction, the reproduction signal shown in FIG. The tracking error signal has a lag phase.

In the seek direction detection, when the light spot is moving in the outer circumferential direction, the tracking error signal shown in FIG. 4B leads the phase of the traverse signal included in the reproduced signal shown in FIG. 4A. However, when the light spot is moving in the inner circumferential direction, the property that the tracking error signal shown in FIG. 4B has a delay phase with respect to the traverse signal included in the reproduction signal shown in FIG. 4A is used. doing.

Thus, the seek direction detecting circuit 55
Detects the moving direction of the light spot and outputs a direction signal (DE
R) is supplied to the servo processing circuit 56. As a result, the servo processing circuit 56 can specify the seek direction to the optical pickup 53 and move the objective lens in the cross-track direction by the stable two-axis actuator to perform an accurate seek operation.

The signal processing apparatus according to the present embodiment records information by forming pits on an optical disc or irradiating a laser spot on a groove, and irradiates a laser beam onto the optical disc to record pits or grooves. A signal processing device for performing signal processing for reproducing information recorded in a first laser beam having a first wavelength and a second laser beam having a second wavelength longer than the first wavelength. A laser spot of a first laser beam and a laser spot of a second laser beam are formed on an optical disk by using the optical pickups 1 and 20 having the optical pickup, and the return light of the first laser beam from the optical disk is used for recording and reproducing information. Since the return light of the second laser light from the optical disk is used for servo control of the optical pickup, It is possible to determine the depth of pits or grooves in a position that satisfies the raw optimum conditions,
Higher density can be achieved for recording or reproduction.

Further, in the signal processing device of the present embodiment, the first wavelength is selected so that the relative value of the return light from the pit or groove and the return light from other than the pit or groove becomes maximum. Therefore, the S /
N can be improved, and thereby the margin can be improved, and as a result, the recording density can be improved.

Further, in the signal processing apparatus of the present embodiment, in the above description, the optical pickup 20 is configured to irradiate a laser spot by the first laser beam onto the optical disc.
Since the optical pickup has an objective lens and a second objective lens that irradiates a laser spot of the second laser beam onto the optical disc and combines the first objective lens and the second objective lens, Since laser beams of two wavelengths are handled by the two objective lenses, an objective lens having no chromatic aberration can be used for any wavelength, and the two objective lenses of the optical pickup are combined. The tracking servo and the focus servo can be easily performed by the tracking coil and the focus coil of the same two-axis actuator.

Further, in the servo signal processing device of the present embodiment, the information is obtained by positioning the optical pickup on the optical disk by the servo signal and forming a pit or irradiating the groove with a laser spot. In a servo signal processing apparatus for performing recording and servo signal processing for reproducing information recorded in pits or grooves by irradiating a laser beam on an optical disc, a first laser beam of a first wavelength; 1
Using an optical pickup having a second laser beam of a second wavelength longer than the wavelength of
Forming a laser spot by the first laser light and a laser spot by the second laser light, and using the return light of the first laser light from the optical disk for recording and reproducing information, and returning the second laser light from the optical disk. Is used for at least the positioning servo control of the optical pickup, so that the pit or groove depth can be determined at a position that satisfies the servo optimum condition, so that the stability and accuracy of the servo can be improved.

In the servo signal processing apparatus according to the present embodiment, in the above description, the second wavelength is such that the relative value of the difference signal between the return light from the pit or groove and the return light from other than the pit or groove is maximum. So we choose
The S / N of the servo signal can be improved, thereby improving the margin and consequently the servo characteristics.

Further, in the servo signal processing apparatus according to the present embodiment, an AC component signal of a reproduction signal based on the return light of the first laser light from the optical disk and a return signal of the second laser light from the optical disk are provided. Since the moving direction of the optical pickup is detected from the leading direction or the lagging direction of the phase relative to the tracking error signal based on the light, the seek is performed by using the reproduction signal and the tracking error signal having a good S / N. The direction can be easily detected, and the seek characteristics can be improved.

Further, in the servo signal processing apparatus according to the present embodiment, in the above description, the optical pickup comprises: a first objective lens for irradiating a laser spot of the first laser beam onto the optical disc; A second objective lens for irradiating the laser spot onto the optical disk, the first objective lens and the second objective lens being combined, and the combined first and second objective lenses being combined. At the same time, the optical pickup is driven in the focus direction or the tracking direction. In the optical pickup, laser beams of two wavelengths are handled by two objective lenses. Therefore, an objective lens having no chromatic aberration at any wavelength can be used. In addition, since the two objective lenses of the optical pickup are connected, the tracking coil and the for- Easily it can perform the tracking servo and the focusing servo by Kasukoiru.

Further, the optical disk device of the present embodiment
Information is recorded by positioning an optical pickup on an optical disc and forming pits or irradiating a laser spot on the groove, and irradiating laser light on the optical disc to record information recorded in the pit or groove. In an optical disc device for reproduction,
Using an optical pickup having a first laser beam of a first wavelength and a second laser beam of a second wavelength longer than the first wavelength, a laser spot of the first laser beam on the optical disc and A laser spot is formed by the second laser light, and the return light of the first laser light from the optical disk is used for recording and reproducing information, and the return light of the second laser light from the optical disk is positioned at least in the optical pickup. Since it was used for servo control,
Since the depth of the pit or groove can be determined at a position that satisfies the optimum conditions for reproduction, the density can be increased for recording or reproduction, and the pit or groove can be positioned at a position that satisfies the optimum conditions for servo. Can be determined, so that the stability and accuracy of the servo can be improved.

In the above-described embodiment, only the optical disk has been described.
Can be similarly applied.

In the above-described embodiment, only an example in which the present invention is applied to a servo signal generation device of an optical disk device is described. However, the present embodiment is applied to a servo signal generation device of another electronic device having a configuration in which an actuator is controlled by a servo signal. It goes without saying that it may be applied.

[0056]

The signal processing apparatus of the present invention records information by forming pits on an optical disc or irradiating a laser spot on a groove, and irradiates a laser beam onto the optical disc to form the pits. Alternatively, in a signal processing device for performing signal processing for reproducing information recorded in the groove, a first laser beam having a first wavelength and a second laser beam having a second wavelength longer than the first wavelength are provided. Forming a laser spot by the first laser beam and a laser spot by the second laser beam on the optical disc by using an optical pickup having a laser beam, and returning the first laser beam from the optical disc; Using the light for recording and reproducing information, and returning the second laser light from the optical disk to the optical pickup. Since the servo control is used, the pit or groove depth can be determined at a position that satisfies the optimum reproduction condition, so that the recording or reproduction can be performed at a high density. .

In the signal processing device of the present invention, the first wavelength has a maximum relative value between return light from the pit or the groove and return light from a portion other than the pit or the groove. So you choose
It is possible to improve the S / N of the reproduction signal, thereby improving the margin, and as a result, it is possible to improve the recording density.

In the signal processing apparatus according to the present invention, the optical pickup includes: a first objective lens for irradiating a laser spot of the first laser beam onto the optical disc; and a second laser beam. And a second objective lens for irradiating a laser spot on the optical disc with the first objective lens and the second objective lens. Therefore, in the optical pickup, two objective lenses are used. Since it handles laser beams of two wavelengths,
An objective lens having no chromatic aberration can be used for any wavelength, and since the two objective lenses of the optical pickup are combined, the tracking servo can be easily performed by the tracking coil and the focus coil of the same two-axis actuator. In addition, there is an effect that focus servo can be performed.

Further, in the servo signal processing device of the present invention, the information is recorded by positioning the optical pickup on the optical disk by the servo signal and forming pits or irradiating the groove with a laser spot. A servo signal processing device for performing servo signal processing for reproducing information recorded in the pits or grooves by irradiating the optical disk with laser light, wherein a first laser light of a first wavelength; Using an optical pickup having a second laser beam of a second wavelength longer than the first wavelength, a laser spot of the first laser beam and a laser spot of the second laser beam on the optical disc. Is formed, and the return light of the first laser light from the optical disc is recorded as information. Since the return light of the second laser light from the optical disk is used for at least the positioning servo control of the optical pickup, the depth of the pit or groove is determined at a position satisfying the servo optimum condition. Therefore, there is an effect that the stability and accuracy of the servo can be improved.

In the servo signal processing apparatus according to the present invention, the second wavelength is a relative value of a difference signal between return light from the pit or the groove and return light from other than the pit or the groove. Is maximized, so that the S / N of the servo signal can be improved, thereby improving the margin and consequently improving the servo characteristics.

Further, in the servo signal processing apparatus of the present invention, an AC component signal of a reproduction signal based on a return light of the first laser light from the optical disk and a servo signal processing device of the second laser light are provided. Since the moving direction of the optical pickup is detected from the leading direction or the lagging direction of the phase relative to the tracking error signal based on the return light, the reproduction signal and the tracking error signal having a good S / N can be used. Accordingly, the seek direction can be easily detected, and an effect that the seek characteristics can be improved can be achieved.

Further, in the servo signal processing apparatus of the present invention, in the above, the optical pickup comprises: a first objective lens for irradiating a laser spot of the first laser beam onto the optical disk; A second objective lens for irradiating a laser spot by light onto the optical disc, wherein the first objective lens and the second
And the combined first and second objective lenses are simultaneously driven in the focus direction or the tracking direction. Therefore, in the optical pickup, two objective lenses are used for two objective lenses. Since a laser beam of a wavelength is handled, an objective lens having no chromatic aberration can be used for any wavelength, and since the two objective lenses of the optical pickup are combined, the tracking coil of the same two-axis actuator can be used. In addition, there is an effect that tracking servo and focus servo can be easily performed by the focus coil.

The optical disk apparatus of the present invention records information by positioning an optical pickup on an optical disk and forming pits or irradiating a laser spot on a groove, and irradiating a laser beam on the optical disk. In an optical disk device for reproducing information recorded in the pits or grooves by irradiating, a first laser beam of a first wavelength and a second laser beam of a second wavelength longer than the first wavelength Using an optical pickup having light, the first
Forming a laser spot by the second laser light and a laser spot by the second laser light;
Since the return light of the laser light from the optical disc is used for recording and reproducing information, and the return light of the second laser light from the optical disc is used for at least the positioning servo control of the optical pickup. Since the pit or groove depth can be determined at a position that satisfies the conditions, high density can be achieved for recording or reproduction, and the pit or groove depth can be determined at a position that satisfies the servo optimum conditions. Since the length of the servo can be determined, there is an effect that the stability and accuracy of the servo can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an optical pickup according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of another optical pickup according to the embodiment of the present invention.

FIG. 3 is a diagram showing formation of a spot by another optical pickup according to the embodiment of the present invention.

4A and 4B are diagrams illustrating a method of detecting a moving direction according to the embodiment of the present invention. FIG. 4A illustrates a reproduction signal, and FIG. 4B illustrates a tracking signal.

FIG. 5 is a block diagram illustrating a configuration of an optical disk device according to an embodiment of the present invention.

FIG. 6 is a diagram showing detection of a tracking error signal and a reproduction signal in the related art.

FIG. 7 is a diagram showing characteristics of a conventional tracking error signal and the amount of reflected light.

[Explanation of symbols]

1 Optical pickup 2 Laser diode L
D1, 3 ... Collimator lens, 4 ... Polarizing beam splitter PBS1, 5 ... Wavelength selection element, 6
... Objective lens, 7 Condenser lens, 8 Detector 1, 9 Laser diode LD2, 10 Collimator lens, 11 Polarizing beam splitter PBS2, 12 Condenser lens, 13 Detectors 2, 14: Reproduction amplifier, 15: Comparator, 16
... Comparator, 17 ... Optical disk, 20 ... Optical pickup, 21 ... Objective lens, 22 ... Objective lens, 30 ... Land, 31 ... Groove, 32 ... Land, 33 ... Spot made by LD2, 34: spot made by LD1, 50: optical disk, 51: spindle motor, 52: objective lens, 53: optical pickup, 54: reproduction signal processing circuit, 55: seek direction detection circuit, 56: Servo processing circuit,

Claims (8)

[Claims] 1. Recording information by forming pits on an optical disc or irradiating a laser spot on a groove, and irradiating a laser beam on the optical disc to record information on the pits or the grooves. A signal processing apparatus for performing signal processing for reproducing a signal, comprising: an optical pickup having a first laser beam of a first wavelength and a second laser beam of a second wavelength longer than the first wavelength. And forming a laser spot by the first laser light and a laser spot by the second laser light on the optical disk, and using the return light of the first laser light from the optical disk for recording and reproducing information. The return light of the second laser light from the optical disk is used for servo control of the optical pickup. Signal processing apparatus characterized by the. 2. The signal processing device according to claim 1, wherein the first wavelength has a maximum relative value between return light from the pit or the groove and return light from a portion other than the pit or the groove. A signal processing device. 3. The signal processing device according to claim 1, wherein the optical pickup includes a first objective lens that irradiates a laser spot of the first laser light onto the optical disk, and a second laser light. A signal processing device, comprising: a second objective lens for irradiating a laser spot onto the optical disc; and combining the first objective lens and the second objective lens. 4. An optical pickup is positioned on an optical disk by a servo signal and information is recorded by forming pits or irradiating a laser spot on a groove, and irradiating the optical disk with a laser beam. In a servo signal processing apparatus for performing servo signal processing for reproducing information recorded in the pit or the groove, a first laser beam of a first wavelength and a second wavelength longer than the first wavelength Forming a laser spot by the first laser light and a laser spot by the second laser light on the optical disc using an optical pickup having the second laser light; The return light from the optical disk is used for recording and reproduction of information, and the optical disk of the second laser light is used. Servo signal processing apparatus being characterized in that as used at least in the positioning servo control of the optical pickup return light from. 5. The servo signal processing device according to claim 4, wherein the second wavelength is a relative value of a difference signal between a return light from the pit or the groove and a return light from other than the pit or the groove. A servo signal processing device, wherein the maximum value is selected. 6. The servo signal processing device according to claim 4, wherein an AC component signal of a reproduction signal based on a return light of the first laser light from the optical disc and a second laser light from the optical disc. A servo signal processing device, wherein a moving direction of the optical pickup is detected from a leading direction or a lagging direction of a phase relative to a tracking error signal based on return light. 7. The servo signal processing device according to claim 4, wherein the optical pickup is configured to irradiate a laser spot of the first laser beam onto the optical disk, and the second laser beam. A second objective lens for irradiating the laser spot on the optical disc with the first objective lens and the second objective lens, and combining the first objective lens with the first objective lens and the second objective lens. A servo signal processing device for simultaneously driving a second objective lens in a focus direction or a tracking direction. 8. Recording information by positioning an optical pickup on an optical disk and forming pits or irradiating a laser spot on the groove.
An optical disc apparatus for reproducing information recorded in the pits or grooves by irradiating a laser beam on the optical disc, wherein a first laser beam having a first wavelength and a second laser beam longer than the first wavelength are provided. Forming a laser spot of the first laser beam and a laser spot of the second laser beam on the optical disc using an optical pickup having a second laser beam having a wavelength of An optical disk device, wherein the return light from the optical disk is used for recording and reproducing information, and the return light of the second laser light from the optical disk is used for at least positioning servo control of the optical pickup. .