JP2001143278A - Optical pickup device and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the accurate measurement of a stray light component included in the signal that is outputted from a light receiving part. SOLUTION: In steps S1-S5, an objective lens 22 is moved to the upper and lower limit positions of a focus moving range and the 1st and 2nd levels of an RF signal are stored when the lens 22 is set at its upper and lower limit positions respectively. The 1st and 2nd levels of the RF signal are compared with each other in a step S6. In steps S7 and S8, the levels of the RF signal set when the lens 22 is kept at its upper limit position, a focusing error signal and a tracking error signal are measured when the 1st level is higher than the 2nd one and then the levels of the RF signal set when the lens 22 is set at its lower limit position, the focusing error signal and the tracking error signal (stray light component) are measured when the 1st level is lower than the 2nd one. Then the offset of every signal is canceled according to the selectively measured levels in a step S9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device capable of removing stray light components contained in a signal output from a light receiving device and stabilizing servo control of a driving device of an objective lens, and a control of the optical pickup device. About the method.

[0002]

2. Description of the Related Art Conventionally, an optical pickup device used for a recording and / or reproducing apparatus for an optical disk includes a light source for emitting a light beam applied to the optical disk, and a signal for the optical disk by converging the light beam emitted from the light source. It has an objective lens for irradiating the recording surface, a light receiving unit for detecting a return light beam reflected on the signal recording surface of the optical disk, and the like.
The objective lens is held by a two-axis actuator so as to be movable in a focusing direction parallel to the optical axis and a tracking direction orthogonal to the optical axis. The light beam emitted from the light source is converged by the objective lens, irradiated on the optical disk, and the return light beam reflected on the signal recording surface of the optical disk is received by the light receiving unit via the objective lens,
Photoelectric conversion is performed.

Further, this optical pickup device generates an RF signal, a focusing error signal, and a tracking error signal based on an output signal from a light receiving section.
An amplifier and a servo control circuit that performs servo control of a two-axis actuator that holds the objective lens based on a focusing error signal and a tracking error signal. The output signal from the light receiving unit is supplied to an RF amplifier, and the RF amplifier generates an RF signal, a focusing error signal, and a tracking error signal based on the output signal, and servo-controls the focusing error signal and the tracking error signal. Supply to control circuit.
The servo control circuit performs servo control of the biaxial actuator to move the objective lens in the focusing direction and the tracking direction so that the light beam can be accurately scanned.

Meanwhile, among components of the light beam emitted from the light source, there is a so-called stray light component that is received by the light receiving unit through an unexpected path from the light source to the light receiving unit. When this stray light is received by the light receiving unit, it is added to the output signal output from the light receiving unit. Therefore, an offset error occurs in the RF signal, the focusing error signal, and the tracking error signal generated by the RF amplifier, and it is not possible to obtain an accurate RF signal, focusing error signal, and tracking error signal. Would. For this reason, the objective lens is not accurately driven and controlled by the two-axis actuator, and cannot accurately scan the light beam. Particularly, in a module such as a laser coupler in which a light source, a light receiving unit, an optical element, and the like are provided on one chip, the stray light is easily generated because the light source and the light receiving unit are provided close to each other.

Therefore, in the initial operation, the optical pickup device moves the objective lens to the lower limit in the focusing direction in order to prevent the light reflected on the optical disk surface from being received by the light receiving portion, and changes this state to a stray light component. Only the light is received, and the DC component of the RF signal at this time is measured. The optical pickup device subtracts this DC component, which is a stray light component, from a focusing error signal and a tracking error signal during a normal operation of recording and reproducing an optical disk. As a result, the stray light component is removed from the focusing error signal and the tracking error signal, so that the servo control circuit can accurately control the servo of the two-axis actuator.

[0006]

By the way, when an optical disk is rotated by a disk rotation operation unit provided in a recording and / or reproducing apparatus of the optical disk, a run-out occurs. Therefore, as described above, the objective lens is moved to the lower limit in the focusing direction to prevent the reflected light from being reflected on the optical disk surface or the reflected light being received by the light receiving unit, and the DC component of the RF signal, which is only the stray light component, is measured. Even when the optical disk is rotating, the light receiving unit may receive the reflected light reflected on the optical disk surface due to the surface shake of the rotating optical disk. In this case, the reflected light component is added to the output signal from the light receiving unit, and therefore, the DC component serving as the stray light component cannot be accurately measured. Therefore, the optical pickup device cannot remove an accurate stray light component from a focusing error signal or a tracking error signal during a steady operation,
The information signal cannot be accurately recorded, and the information signal recorded on the optical disc cannot be reproduced.

Accordingly, the present invention is to accurately measure a stray light component included in a signal output from a light receiving means, remove the measured stray light component from a focusing error signal or a tracking error signal, and to drive an objective lens driving means. It is an object to provide an optical pickup device and a control method of the optical pickup device which can stabilize the servo control of the optical pickup device.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an optical pickup device according to the present invention comprises: an objective lens disposed to face a signal recording surface of an optical disc; Driving means for moving the objective lens in a focusing direction parallel to the optical axis of the lens and in a tracking direction orthogonal to the optical axis of the objective lens, and light receiving means for receiving a return light beam reflected on the signal recording surface of the optical disk, The first level of the RF signal output from the light receiving means when the objective lens is moved to the lower limit in the focusing direction by the driving means, and the output from the light receiving means when the objective lens is moved to the upper limit in the focusing direction by the driving means Control means for measuring a second level of the RF signal to be applied, and a first level and a second level which are measured by the control means.
And servo control means for performing servo control of the driving means based on the focusing error signal and the tracking error signal generated by the control means. Then, the control means compares the first level with the second level, and when the first level is larger than the second level, moves the objective lens to an upper limit, and outputs an RF signal, a focusing error signal, and a tracking error signal. Measuring at least one level of the error signal,
Is lower than the second level, the objective lens is moved to the lower limit, and at least one of the RF signal, the focusing error signal, and the tracking error signal is moved.
Measuring the two levels, and canceling at least the offset of the focusing error signal and the tracking error signal based on the selectively measured levels, and the servo control circuit outputs the offset error and the tracking error signal with the offset canceled. The servo control of the driving means is performed based on the above.

Further, in order to solve the above-mentioned problems, the control method of the optical pickup device according to the present invention moves the objective lens of the optical pickup device to a lower limit and an upper limit of a focus moving range by a driving mechanism, respectively. The first level of the RF signal output from the light-receiving element of the optical pickup device when is moving to the lower limit and the second level of the RF signal when the objective lens is moving to the upper limit are stored in the storage element. Storing; and comparing the first level with the second level; and when the first level is greater than the second level, moving the objective lens to an upper limit;
Measuring at least one of the RF signal, the focusing error signal, and the tracking error signal, and moving the objective lens to the lower limit when the first level is smaller than the second level; Measuring at least one of a tracking error signal and a tracking error signal; canceling at least an offset of the focusing error signal and the tracking error signal based on the selectively measured level; and focusing with the offset canceled. Performing servo control of the drive mechanism based on the error signal and the tracking error signal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disc reproducing apparatus using an optical pickup device to which the present invention is applied will be described with reference to the drawings.

As shown in FIG. 1, the optical disk reproducing apparatus 1 irradiates a light beam to a reproduction-only optical disk 10 on which information signals such as a musical sound signal, a video signal, and a processing signal processed by a computer are recorded. An optical pickup device 11 that reads out an information signal from the optical disk 5 by detecting the reflected return light beam, and converts a digital signal from the optical pickup device 11 into an analog signal to generate a reproduction signal. A signal processing circuit 12, an amplifier 13 for amplifying the reproduced signal, an output device 14 such as an earphone, a headphone, and a speaker for outputting the reproduced signal amplified by the amplifier 13, the optical pickup device 11, the signal processing circuit 12, and the like. And a main controller 15 for controlling.

Optical pickup device 1 to which the present invention is applied
Reference numeral 1 denotes a module in which a light-emitting unit, a light-receiving unit, a prism, and the like are integrated on one chip, an objective lens disposed to face the optical disc 10, and the like. Then, the optical pickup device 1
1 is that a light beam emitted from a light emitting unit is focused by an objective lens and irradiates a signal recording surface of an optical disc 10;
The return light beam reflected on the signal recording surface of the optical disk 10 is irradiated on the light receiving unit, so that the information signal recorded on the optical disk 10 is read.

The signal processing circuit 12 includes an error detection / correction circuit for detecting and correcting a code error and a digital / analog conversion circuit (D / A / D converter) for converting a digital signal into an analog signal.
A conversion circuit). The signal processing circuit 12 uses an error detection and correction circuit based on the RF signal supplied from the RF amplifier included in the optical pickup device 11 based on the RF signal in which the stray light component received by the light receiving unit of the optical pickup device 11 has been canceled. After detecting and correcting a code error in the signal, the error-corrected RF signal is converted into an analog signal by an A / D conversion circuit to generate a reproduced signal.

The main controller 15 controls the optical pickup device 11, the signal processing circuit 12, and the like based on operation signals from the operation unit. For example, when a playback start button constituting the operation unit is pressed, an operation signal indicating the start of playback is input to the main controller 15, and the main controller 15 sends the operation signal to the optical pickup device 11 or the signal processing circuit 12 based on the operation signal. And so on.

Incidentally, the above-described optical pickup device 1
As shown in FIG. 2, reference numeral 1 denotes a module 21 such as a laser coupler in which a light-emitting unit, a light-receiving unit, and the like are integrated on one chip, and an objective lens 22 disposed to face the optical disk 10 and the like. Is provided. The module 21 includes a light emitting unit 21a that emits a light beam L1, a light receiving unit 21b that detects a return light beam L2 reflected on the signal recording surface of the optical disc 10, and a light beam L1 emitted from the light emitting unit 21a. The light beam L guided to the objective lens 22 and returned
And a prism for guiding the light 2 to the light receiving portion 21b. The light receiving section 21b is divided into four or eight parts so that the RF amplifier can generate an RF signal, a focusing error signal, and a tracking error signal. When the light beam L1 is emitted from the light emitting unit 21a, the optical pickup device 11 converges the light beam L1 on the objective lens 22 and irradiates the light beam onto the signal recording surface of the optical disk 10. The return light beam L2 reflected by the recording surface is detected by the light receiving section 21b via the objective lens 22, and the information signal recorded on the optical disk 10 is read. Then, the light receiving section 21b
Converts the return light beam L2 reflected by the detected signal recording surface of the optical disk 10 into an electric signal. The optical pickup device 11 may be provided with a laser diode forming the light receiving unit and a photodiode forming the light receiving unit separately.

The objective lens 22 is held by a biaxial actuator 23 serving as a driving mechanism, and is moved in a focusing direction parallel to the optical axis of the objective lens 22 and in a tracking direction orthogonal to the optical axis of the objective lens 22. You.
The biaxial actuator 23 includes a focusing coil to which a focusing error signal for moving the objective lens 22 in the focusing direction is supplied,
The objective lens 22 is moved in the focusing direction and the tracking direction by a tracking coil to which a tracking error signal is supplied, and a focusing error signal supplied to the focusing coil and a tracking error signal supplied to the tracking coil. It has a magnet and the like for generating a driving force.

When a focusing error signal is supplied to the focusing coil, such a biaxial actuator 23 generates a driving force to move the focusing coil in a direction parallel to the optical axis of the objective lens 22, thereby causing the objective lens 22 to emit light. Move in the direction parallel to the axis to perform focus control. When the tracking error signal is supplied to the tracking coil, the biaxial actuator 23 generates a driving force to move the tracking error coil in a plane direction orthogonal to the optical axis of the objective lens 22, and the
Is moved in a plane direction orthogonal to the optical axis to perform tracking control. The moving range of the objective lens 22 by the biaxial actuator 23 is set to be larger than the thickness of the optical disc 10 and 1.2 mm so that the focal point where the light beam L1 is focused is formed above and below the optical disc 10. 4 mm.

Further, as shown in FIG. 2, the optical pickup device 11 includes an RF amplifier 31 for amplifying an output signal output from the light receiving section 21b, and a two-axis actuator 23 based on a signal from the RF amplifier 31. A servo control circuit 32 for performing servo control; a control circuit 33 for measuring the level of a DC component of a signal supplied from the RF amplifier 31 to the servo control circuit 32; a storage circuit 34 for storing the level measured by the control circuit 33; And a drive circuit 35 for driving and controlling the two-axis actuator 23 based on a servo signal from the servo control circuit 32.

The RF amplifier 31 generates an RF signal, a focusing error signal, and a tracking error signal based on the output signal from the light receiving section 21b. For example, a focus error signal is generated by an astigmatism method, and a tracking error signal is generated by a three-beam method or a push-pull method. Then, the RF amplifier 31 supplies the RF signal to the signal processing circuit 12 and supplies the focus error signal and the tracking error signal to the servo control circuit 32.

The servo control circuit 32 is supplied with a focusing error signal and a tracking error signal from the RF amplifier 31 described above. Here, the servo control circuit 32
The stray light component is removed from the focusing error signal and the tracking error signal supplied to the control circuit 33 by the control circuit 33. Then, the servo control circuit 32 generates a focusing servo signal based on the focusing error signal from which the stray light component has been removed by the control circuit 33 so that the focusing error signal becomes zero. Further, the servo control circuit 32 generates a tracking servo signal based on the tracking error signal from which the stray light component has been removed by the control circuit 33 so that the tracking error signal becomes zero. Then, the servo control circuit 32 supplies the focusing servo signal and the tracking servo signal to the drive circuit 35.

The control circuit 33 first moves the objective lens 22 to the lower limit position most distant from the optical disk 10 and the upper limit position closest to the optical disk 10 by the biaxial actuator 23. Here, the upper limit position and the lower limit position of the objective lens 22 in the focusing direction are positions separated from each other by 1.4 mm, which is larger than the thickness of the optical disc 2 of 1.2 mm. That is, the lower limit position and the upper limit position of the objective lens 22 are in a state where the focal point where the light beam L1 is focused is formed below or above the optical disc 10, and the light beam L1 is reflected on the signal recording surface of the optical disc 10. This is a position where the light beam L2 is not radiated to the light receiving portion 21b. Therefore, when the objective lens 22 is at the lower limit position and the upper limit position, the return light beam L2 reflected by the optical disk 10 is emitted from the light emitting unit 21a to the light receiving unit 21b without being irradiated to the light receiving unit 21b. Only the stray light component of the light beam is irradiated. The control circuit 33 includes the servo control circuit 32 and the drive circuit 3
The control signal for moving the objective lens 22 to the upper limit position and the lower limit position in the focusing direction is supplied to the focusing coil constituting the biaxial actuator 23 via 5 to move the objective lens 22 to the upper limit position and the lower limit position. .

When the objective lens 22 is at the lower limit position and at the upper limit position, the control circuit 33 emits a light beam L1 from the light emitting section 21a and supplies the light beam L1 from the light receiving section 21b to the signal processing circuit 12 via the RF amplifier 31. The level of the DC component of the RF signal is measured. And the control circuit 33
Stores the DC component level (first level) when the objective lens 22 is at the lower limit position and the DC component level (second level) when the objective lens 22 is at the upper limit position. Then, the control circuit 33 compares the first level with the second level. That is, when the optical disk 10 is rotated by the disk rotation operation unit that rotates the optical disk 10, surface run-out occurs. When the objective lens 22 is at the lower limit position or the upper limit position, when the optical disk 10 is shaken, the light receiving portion 21b receives the return light beam L2 reflected on the signal recording surface of the optical disk 10 in addition to the stray light component. The light is received, and it becomes impossible to measure only the stray light component. Therefore, when comparing the first level and the second level, the control circuit 33 determines that the smaller level has no component of the returning light beam L2 reflected by the optical disk 10 and only the stray light component. to decide.

The control circuit 33 controls the objective lens 22
When the first level when is at the lower limit position is larger than the second level when at the upper limit position, the objective lens 22 is moved to the upper limit position by the biaxial actuator.
Then, the control circuit 33 measures the levels of the DC components of the RF signal supplied to the signal processing circuit 12 and the focusing error signal and the tracking error signal supplied to the servo control circuit 32. When the first level when the objective lens 22 is at the lower limit position is smaller than the second level when the objective lens 22 is at the lower limit position, the control circuit 33 moves the objective lens 22 to the lower limit position by the biaxial actuator 23. . Then, the control circuit 33 controls the signal processing circuit 1
The level of the DC component of the RF signal supplied to the control signal 2 and the DC components of the focusing error signal and the tracking error signal supplied to the servo control circuit 32 are measured. Then, the control circuit 33 causes the storage circuit 34 to selectively store the levels of the DC components of the RF signal, the focusing error signal, and the tracking error signal when the objective lens 22 is at the lower limit position or the upper limit position in the focusing direction.

When the optical disk 10 is reproduced, that is, when the optical disk 10 is in a steady state, the level of the DC components of the focusing error signal and the tracking error signal supplied from the RF amplifier 31 to the servo control circuit 32 is determined. When the objective lens 22 stored in the storage circuit 34 at the time of the initial operation is at the lower limit position or the upper limit position in the focusing direction, the level of the DC component of the focusing error signal and the tracking error signal is subtracted,
The stray light component is removed from the focusing error signal and the tracking error signal supplied from the RF amplifier 31 to the servo control circuit 32. Then, the above-described servo control circuit 32 supplies a focusing error signal and a tracking error signal from which the stray light component has been removed to the drive circuit 35.

In the steady state, the control circuit 33
RF supplied from the RF amplifier 31 to the signal processing circuit 12
The level of the DC component of the RF signal when the objective lens 22 stored in the storage circuit 34 is at the lower limit position or the upper limit position in the focusing direction during the initial operation is subtracted from the level of the DC component of the signal. The stray light component is removed from the RF signal supplied to the circuit 32. The signal processing circuit 12 outputs the RF signal from which the stray light component has been removed.
Error detection and correction are performed based on the signal, and the digital signal is converted into an analog signal.

The drive circuit 35 drives and controls the two-axis actuator 23 for driving the objective lens 22 constituting the optical pickup device 11 based on the focusing servo signal and the tracking servo signal generated by the servo control circuit 32. That is, the drive circuit 35 supplies power to the focusing coil constituting the biaxial actuator 23 based on the focusing servo signal, and moves the objective lens 22 in a focusing direction parallel to the optical axis of the objective lens 22. Further, the drive circuit 35 supplies power to a tracking coil constituting the biaxial actuator 23 based on the tracking servo signal, and moves the objective lens 22 in a tracking direction orthogonal to the optical axis of the objective lens 22.

The above-described optical disk reproducing apparatus 1 detects a stray light component of the optical pickup device 11 as follows in an initial operation such as at the time of shipment or when the main power is turned on. That is, as shown in FIG. 3, in step S1, the control circuit 33 drives the light emitting unit 21a to emit the light beam L1 from the light emitting unit 21a. Then, the light beam L1 becomes
The light is converged by the objective lens 22 and is irradiated on the signal recording surface of the optical disc 10. Then, the return light beam L2 reflected on the signal recording surface of the optical disk 10 is received by the light receiving section 21b and converted into an electric signal.

Next, in step S2, the control circuit 33 moves the objective lens 22 to the lower limit in the focusing direction to measure the level (first level) of the DC component of the RF signal when the objective lens 22 is at the lower limit position. Move to position. That is, the control circuit 33 communicates with the two-axis actuator 2 via the servo control circuit 32 and the drive circuit 35.
The control signal for moving the objective lens 22 to the lower limit position in the focusing direction is supplied to the focusing coil constituting the third lens unit 3 to move the objective lens 22 to the lower limit position. Then, the control circuit 33 determines in step S3
The level (first level) of the DC component of the RF signal supplied to the signal processing circuit 12 is measured, and the measured level is stored in the storage circuit 34.

Then, in step S4, the control circuit 33 moves the objective lens 22 to the upper limit in the focusing direction in order to measure the level (second level) of the DC component of the RF signal when the objective lens 22 is at the upper limit position. Move to position. That is, the control circuit 33 communicates with the two-axis actuator 2 via the servo control circuit 32 and the drive circuit 35.
A control signal for moving the objective lens 22 to the upper limit position in the focusing direction is supplied to the focusing coil forming the third coil 3, and the objective lens 22 is moved to the upper limit position. Then, the control circuit 33 determines in step S5
The level (second level) of the DC component of the RF signal supplied to the signal processing circuit 12 is measured, and the measured level is stored in the storage circuit 34.

The control circuit 33 determines in step S6
The first level when the objective lens 22 is at the lower limit position is compared with the second level when the objective lens 22 is at the upper limit position. If the first level is larger than the second level, the process proceeds to step S7. If the first level is not higher than the second level, the process proceeds to step S8.

That is, in step S6, the control circuit 3
3 is that when the first level when the objective lens 22 is at the lower limit position is larger than the second level when the objective lens 22 is at the upper limit position,
When the objective lens 22 is at the upper limit position where the level is small, the component of the light beam L2 received by the light receiving unit 21b does not include the component of the return light beam L2 reflected by the optical disc 10, and the light beam It is determined that the component of L2 is closer to the stray light component alone, and the process proceeds to step S7 for measuring the level of the DC component of the RF signal and the focusing error signal and the tracking error signal when the objective lens 22 is at the upper limit position. Further, when the first level when the objective lens 22 is at the lower limit position is not higher than the second level at the upper limit position, that is, when the second level is larger than the first level, Lens 22
Is at the lower limit position where the level is small,
The component of the light beam L2 received by the optical disc 1b does not include the component of the return light beam L2 reflected by the optical disk 10, and it is determined that the component of the light beam L2 is closer to only the stray light component. The process proceeds to step S8 for measuring the level of the signal and the DC components of the focusing error signal and the tracking error signal.

The control circuit 33 determines in step S7
The objective lens 22 is moved to the upper limit position by the two-axis actuator 23, and the level of the DC component of the RF signal supplied to the signal processing circuit 12 and the focusing error signal and the tracking error signal supplied to the servo control circuit 32 is measured. The storage circuit 34 stores the level of each DC component of the RF signal and the focusing error signal and the tracking error signal. Further, in step S8, the control circuit 33 moves the objective lens 22 to the lower limit position by the two-axis actuator 23, and the signal processing circuit 12
And the level of the DC component of the focusing error signal and the tracking error signal supplied to the servo control circuit 32 and the level of the DC component of the RF signal and the focusing error signal and the tracking error signal. 34.

That is, the level of each DC component of the RF signal, focusing error signal and tracking error signal selectively stored in the storage circuit 34 in step S7 or step S8 becomes the level of the stray light component of each signal.

Here, for example, when a reproduction start button constituting an operation section of the optical disc reproducing apparatus 1 is pressed, a spindle motor constituting a disc rotation operation section for rotating the optical disc 10 is driven based on this signal, and Then, the optical pickup device 11 is driven. Then, the optical pickup device 11 emits a light beam L1 from the light emitting unit 21a, irradiates the signal recording surface of the optical disc 2 with the light beam L1, and receives a return light beam L2 reflected by the signal recording surface of the optical disc 2 as a light receiving unit. By detecting at 21b, an optical signal is converted into an electric signal. Then, the light receiving section 21b supplies the electric signal to the RF amplifier 31. Then, RF amplifier 3
1 generates an RF signal, a focusing error signal, and a tracking error signal based on an output signal from the light receiving unit 21b, supplies the focusing error signal and the tracking error signal to the servo control circuit 32, and converts the RF signal into a signal processing circuit. 12

Here, in step S9 of FIG. 3, the control circuit 33 transmits the signal from the RF amplifier 31 to the servo control circuit 32.
Subtracting the level of the DC component of the focusing error signal and the tracking error signal stored in the storage circuit 34 in step S7 or step S8, that is, the stray light component from the level of each DC component of the focusing error signal and the tracking error signal supplied to A stray light component during the reproducing operation is removed from the focusing error signal and the tracking error signal. Thereafter, the servo control circuit 32 drives and controls the two-axis actuator 23 that drives the objective lens 22 included in the optical pickup device 11 based on the focusing error signal from which the stray light component has been removed and the tracking error signal. As a result, the two-axis actuator 23 is controlled by the servo control circuit 32 based on the focusing error signal and the tracking error signal from which the stray light component has been removed, so that the servo can be stabilized.

At the same time, in step S9, the control circuit 33 determines the level of the DC component of the RF signal stored in the storage circuit 34 in step S7 or step S8 from the RF signal supplied from the RF amplifier 31 to the signal processing circuit 12. That is, the stray light component is subtracted, and the stray light component during the reproducing operation is removed from the RF signal. Then, based on the RF signal from which the stray light component has been removed, the signal processing circuit 12
After performing error detection and correction, the digital signal is converted into an analog signal, that is, a reproduced signal, and supplied to the amplifier 13. The reproduced signal amplified by the amplifier 13 is output from an output device 14 such as an earphone, a headphone, and a speaker. Here, the signal processing circuit 12 performs error detection and correction and digital / analog conversion on the RF signal supplied from the RF amplifier 31 after the stray light component is removed by the control circuit 33. Noise can be reduced.

In the optical disk reproducing apparatus 1 as described above,
In steps S2 to S8, the control circuit 33 of the optical pickup device 11 measures the DC component of the RF signal, the focusing error signal, and the tracking error signal when measuring the stray light component without being affected by, for example, surface deviation of the optical disk 10. Is measured at the upper limit position and the lower limit position of the objective lens 22, so that the stray light component of each signal can be accurately calculated. Accordingly, since the optical pickup device 11 can surely cancel the stray light component from the focusing error signal and the tracking error signal, the focusing and tracking control of the objective lens 22 can be performed accurately, and the light beam L1 can be accurately formed. Since the scanning can be performed and the stray light component can be surely canceled from the RF signal, the information signal recorded on the optical disk 10 can be accurately output. That is, the optical disc reproducing device 1
Can perform servo control in a stable state, and in addition, can stably remove a stray light component from an RF signal, so that reproduction characteristics can be improved as compared with a conventional optical disk reproduction device.

In the above example, steps S2 to S8 for measuring the stray light component are performed at the time of shipment or when the main power is turned on. May be performed.

Although the optical disk reproducing apparatus using the optical pickup device 11 to which the present invention is applied has been described above, the present invention is not limited to this. A recording and / or reproducing apparatus for a magneto-optical disk provided with a recording medium and / or a recording and / or reproducing apparatus for a write-once optical disk such as a phase change optical disk.

[0040]

According to the present invention, the level of the RF signal is measured at two positions at the lower limit position and the upper limit position of the objective lens in the focusing direction, and the level at the smaller position is determined as the stray light component. In addition, the stray light component can be accurately calculated without being affected by surface fluctuation of the optical disk, and the servo control of the drive mechanism of the objective lens can be stabilized. Therefore, the present invention can reliably record or reproduce the information signal.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disk reproducing apparatus using an optical pickup device to which the present invention has been applied.

FIG. 2 is a block diagram of the optical pickup device.

FIG. 3 is a flowchart illustrating an operation of a control circuit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 optical disk reproducing device, 10 optical disk, 11 optical pickup device, 12 signal processing circuit, 21 module, 21 a light emitting unit, 21 b light receiving unit, 22 objective lens, 23 two-axis actuator, 31 RF amplifier, 3
2 Servo control circuit, 33 control circuit, 34 storage circuit, 35 drive circuit

Claims (2)

[Claims] 1. An objective lens disposed to face a signal recording surface of an optical disc, holding the objective lens, and a focusing direction parallel to an optical axis of the objective lens and orthogonal to an optical axis of the objective lens. Driving means for moving the objective lens in a tracking direction, light receiving means for receiving a return light beam reflected on the signal recording surface of the optical disc, and moving the objective lens to a lower limit in the focusing direction by the driving means And the second level of the RF signal output from the light receiving means when the objective lens is moved to the upper limit of the focusing direction by the driving means. Control means for measuring a level; and storage for storing the first level and the second level measured by the control means. And a servo control means for performing servo control of the driving means based on the focusing error signal and the tracking error signal generated by the control means, wherein the control means comprises the first level and the second level. When the first level is larger than the second level, the objective lens is moved to an upper limit, and at least one of the RF signal, the focusing error signal, and the tracking error signal is moved. When the first level is smaller than the second level, the objective lens is moved to a lower limit, and at least one of the RF signal, the focusing error signal, and the tracking error signal is measured. Based on the selectively measured level, at least the focusing error signal; To cancel the offset of the fine the tracking error signal, the servo control circuit focusing error signal offset is canceled, and an optical pickup device and performs servo control of the drive means based on the tracking error signal. 2. An object lens of the optical pickup device is moved to a lower limit and an upper limit of a focus movement range by a driving mechanism, respectively, and is output from a light receiving element of the optical pickup device when the objective lens is moving to a lower limit. R
Storing, in a storage element, a first level of an F signal and a second level of the RF signal when the objective lens is moving to an upper limit; and the first level and the second level. And when the first level is greater than the second level,
Moving the objective lens to an upper limit, measuring at least one level of the RF signal, the focusing error signal, and the tracking error signal, and when the first level is smaller than the second level, the objective lens Measuring the level of at least one of the RF signal, the focusing error signal, and the tracking error signal; and, based on the selectively measured level, at least the focusing error signal; A method for controlling an optical pickup device, comprising: a step of canceling an offset of a tracking error signal; and a step of performing servo control of the driving mechanism based on the focusing error signal in which the offset has been canceled and the tracking error signal.