JPH0830984A - Optical disk device - Google Patents

Abstract

PURPOSE:To access a desired track in a short time by suppressing vibration of an objective lens based on displacement or displacing speed of a laser beam projecting position to be detected from return light. CONSTITUTION:Displacement of a laser beam projecting position is detected based on a light receiving result of the return light, and displacement of an optical pickup 22 in whole is eliminated from a displacement detecting result of this laser beam projecting position. By this method, just tracking can quickly be attained immediately after seeking in simple constitution by driving a biaxial actuator to suppress displacement of the objective lens 6 on the optical pickup 22 without providing separately a position detecting mechanism such as a position detecting sensor, etc., but by partly using the conventional light receiving system, etc., thus shortening the time required for access.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device, and is suitable for being applied to the case where a disk-shaped recording medium is irradiated with a laser beam to record and reproduce desired data.

[0002]

2. Description of the Related Art Conventionally, in an optical disk device, the time required for access is shortened by reducing the vibration of the objective lens during seek.

That is, as shown in FIG. 4, in this type of optical disc apparatus 1, a spindle motor 2 drives an optical disc 3 to rotate at a predetermined rotational speed, and the optical disc 3 is driven.
A desired data is recorded on the optical disc 3 by irradiating the optical pickup 4 with a laser beam 5 and the return light of the optical disc 3 is recorded on the optical disc 3 by receiving light from a predetermined light receiving element. Play the data.

Therefore, the optical pickup 4 focuses the laser beam 5 emitted from the laser diode on the information recording surface of the optical disk 3 by the objective lens 6, and further collects the return light from the optical disk 3 by the objective lens 6. Then, the photodetector receives the light. Thereby, the optical disc device 1
Then, in a predetermined matrix circuit, the output signal of this photodetector is subjected to addition / subtraction processing to generate a tracking error signal, a focus error signal, and a reproduction signal.

Here, the objective lens 6 is held by a so-called biaxial actuator so as to be movable vertically and horizontally, and the optical disk device 1 drives the biaxial actuator based on the focus error signal and the tracking error signal to perform tracking. Control and focus control. Regarding the reproduction signal, the optical disc device 1
The signal is binarized by a predetermined signal processing circuit and then decoded by a decoding circuit to reproduce the data recorded on the optical disc 3.

Further, the optical pickup 4 is held so as to move in the radial direction of the optical disk 3 along the guide rod 8 as shown by an arrow A by driving a sled motor composed of a linear actuator, and further, the position is further increased. The sensor detects the amount of movement during this movement (the position detection result can be processed by a predetermined signal processing circuit to obtain speed information). As a result, in the optical disc device 1, the sled motor is driven based on the position detection result to cause the optical pickup 4 to seek a desired recording track.

That is, the optical disc apparatus 1 obtains a position detection signal S1 whose signal level changes in accordance with the amount of movement of the optical pickup 4 from this position sensor, and supplies this to the inverting input terminal of a subtraction circuit 9 formed by an operational amplifier circuit. Position detection signal S
Enter 1. Further, the magneto-optical disk device 1 inputs the target value signal S2 output from the control circuit including an arithmetic processing circuit through the digital-analog conversion circuit to the non-inverting input terminal of the subtraction circuit 9. Here, the target value signal S2 is generated so that, when the optical pickup 4 is sought, the signal level changes according to a preset profile according to the moving distance to the target track.

As a result, the subtraction circuit 9 outputs the error signal of the position detection signal S1 with respect to the target value signal S2 to the phase compensation circuit 10, and the phase compensation circuit 10 phase-compensates this error signal to the drive circuit 11. Output. Drive circuit 11
Drives the voice coil motor 12 of the sled motor based on the output signal of the phase compensating circuit 10, whereby the optical disk device 1 forms a servo loop as a whole and the optical pickup 4 has a profile determined by the target value signal S2. To seek to the target track.

Further, the optical pickup 4 includes an objective lens 6
The optical disc device 1 has a built-in position detection sensor for detecting the position of the position detection sensor, and the optical disc device 1 uses the output signal of the position detection sensor instead of the tracking error signal when seeking.
By driving the axial actuator, the vibration of the objective lens 6 accompanying the movement of the optical pickup 4 is effectively avoided.

That is, in the optical disk device 1, the subtraction circuit 13 formed by the operational amplifier circuit inputs the output signal S3 of the position detection sensor to the inverting input terminal and
The midpoint indicating signal S4 output from the control circuit is input to the non-inverting input terminal, and the output signal S corresponding to the midpoint indicating signal S4 is input.
The error signal of No. 3 is output to the phase compensation circuit 14. Here, the midpoint instruction signal S4 is a control signal of a fixed voltage for holding the objective lens 6 at the midpoint of the movable range.

The phase compensating circuit 14 phase-compensates and outputs the error signal, and the drive circuit 15 composes the phase compensating circuit 1.
The voice coil motor 16 of the biaxial actuator is driven based on the output signal of No. 4. As a result, in the optical disc device 1, a servo loop is formed as a whole, and when the objective lens 6 is displaced from the middle point of the movable range, the biaxial actuator is driven so as to cancel the displacement.

When the seek is further completed, the optical disc apparatus 1 drives the biaxial actuator based on the tracking error signal instead of the output signal S3 of the position detection sensor, thereby quickly forming the just tracking state and recording. The playback operation can be started.

That is, when seeking the optical pickup 4 from the current track a to the target track b, as shown in FIG. After accelerating, the vehicle decelerates when approaching the target track b, thereby driving the sled motor so as to quickly settle to the target track b. At this time, if the objective lens 6 mounted on the optical pickup 4 is allowed to freely vibrate without driving any biaxial actuator (that is, if the extreme loop is not formed in the drive circuit 15 from the position detection sensor through the subtraction circuit 13). ), When the entire optical pickup 4 is first accelerated, it vibrates finely in the state of being largely displaced from the midpoint, and when the optical pickup 4 is decelerated in the latter half, this time it vibrates finely in the state of being largely displaced in the opposite direction. Then, after all, even if the movement of the optical pickup 4 is completed, the optical pickup 4 continuously vibrates (FIG. 5B).

With this, even if the tracking control is started after the seek, it becomes difficult to quickly perform the pulling-in operation by the tracking servo, and eventually it takes time to form the just tracking state. On the other hand, if the biaxial actuator is controlled and the objective lens is held at the midpoint position, the state of just tracking can be formed in a short time immediately after the seek. It is designed to be shortened.

[0015]

However, in order to hold the position of the objective lens 6 at the movable center in this way, a position detecting sensor or other position detecting mechanism for the objective lens 6 is required, and the overall structure is complicated accordingly. There is a problem. If this type of position detection mechanism can be omitted, the structure of the spectral pickup 4 can be simplified, and the mass of the sled motor to be driven can be reduced, so that the structure of the sled motor and the like can be reduced. It can be simplified, and the reliability of the optical disc apparatus as a whole can be improved.

The present invention has been made in consideration of the above points, and proposes an optical disk device capable of accessing a desired recording track in a short time by omitting an objective lens position detecting mechanism such as a position detecting sensor. Is what you are trying to do.

[0017]

In order to solve such a problem, according to the present invention, a light beam emitted from a light source is focused on a disk-shaped recording medium 21 to collect the disk-shaped recording medium 2.
In the optical disk device 20, which records desired data on the optical disk 1, or collects the light beam emitted from the light source on the disk-shaped recording medium 21 to reproduce the data recorded on the disk-shaped recording medium 21, The objective lens 6 that collects the return light obtained from the disc-shaped recording medium 21 while condensing it on the recording medium 21, the light receiving element 22 that receives the return light condensed by the objective lens 6, and the predetermined drive signal Objective lens moving mechanism 1 for moving the objective lens 6 accordingly
6 and the objective lens moving mechanism 16 to the disk-shaped recording medium 2
1. The seek mechanism 12 that moves in the radial direction 1 and the objective lens moving mechanism that detects the position or moving speed of the objective lens moving mechanism 16 in the radial direction of the disk-shaped recording medium 21 and outputs the first detection signal S1. Seek mechanism drive means 9 and 1 for outputting a drive signal to drive the seek mechanism 12 based on the 16 position detection means and the first detection signal S1.
0, 11 and the detection signal of the light receiving element 22, the objective lens 6 in the radial direction of the disk-shaped recording medium 21.
Position detecting means 23, 25, 2 of the objective lens 6 for detecting the position or the movable speed and outputting the second detection signal S5.
6, 27 and the objective lens moving mechanism 16 based on the first and second detection signals S1 and S5.
Or the displacement speed (S6) is detected, and when the objective lens moving mechanism 16 moves in the radial direction of the disk-shaped recording medium 21 based on the detection result (S6), the objective lens moving mechanism 16 moves the objective lens. Driving means 15, 2 of the objective lens moving mechanism 16 for driving the objective lens moving mechanism 16 so as to hold the objective lens 6 at the substantially movable center of the lens 6.
And 9 and 30.

At this time, the position detecting means 2 for the objective lens 6
3, 25, 26, and 27 generate a tracking error signal TE from the output signal of the light receiving element 22 and a light amount detection signal PI whose signal level changes according to the total light amount of the return light,
The second detection signal S5 is generated based on the tracking error signal TE and the light amount detection signal PI.

[0019]

The position or the moving speed of the objective lens 6 with respect to the disk-shaped recording medium 21 is detected based on the detection signal of the light receiving element 22 to generate the second detection signal S5.
If the position of the objective lens 6 with respect to the objective lens moving mechanism 16 or the displacement speed is detected from the detection signal S5 of the objective lens moving mechanism 16 and the first detection signal S1 detected by the position detecting means of the objective lens moving mechanism 16, a separate position detection sensor The displacement (S6) during seek of the objective lens 6 can be detected without the provision of the above. As a result, based on this detection result (S6), the objective lens moving mechanism 16 is driven so as to hold the objective lens 6 substantially at the movable center, seek at a high speed, and immediately after the seek, the state of just tracking is immediately established. Can be formed.

At this time, if the second detection signal is generated based on the tracking error signal and the light amount detection signal, the second detection signal can be generated by utilizing the conventional configuration.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1 in which parts corresponding to those in FIG. 4 are designated by the same reference numerals, 20 denotes an optical disk device as a whole, and an optical disk 21 is rotationally driven by a spindle motor 2 at a predetermined rotational speed.

Here, the optical disc 21 is a magneto-optical disc in which a pre-groove is formed on the information recording surface, and the optical disc device 20 in this embodiment is the optical disc 2
By irradiating the laser beam from the optical pickup 22 to 1 and applying a modulation magnetic field to the irradiation position of the laser beam, desired data is recorded by applying the thermomagnetic recording method. During reproduction, the optical disk device 20 also receives the return light of the optical disk 21 by the optical pickup 22 and detects a change in the plane of polarization, thereby reproducing the data recorded on the optical disk 21 by utilizing the Kerr effect. .

Therefore, the optical pickup 22 collects the laser beam emitted from the laser diode on the information recording surface of the optical disk 21 by the objective lens 6, and further collects the return light from the optical disk 21 by the objective lens 6. The built-in photodetector receives the light and outputs the output signal of the photodetector to the matrix circuit 23.

Here, the matrix circuit 23 subjects the output signal of the photodetector to current-voltage conversion processing, and then performs addition / subtraction processing, whereby the tracking error signal TE whose signal level changes according to the detrack amount and the defocus of the laser beam. A focus error signal FE whose signal level changes according to the amount and a reproduction signal MO whose signal level changes according to the change of the polarization plane of the return light are generated. In addition to this, the matrix circuit 23 also generates a light amount detection signal PI whose signal level changes according to the total light amount of the return light.

As a result, the optical disk device 20 receives the focus error signal FE and the tracking error signal T.
Based on E, a biaxial actuator holding the objective lens 6 is driven to perform tracking control and focus control, and the reproduction signal MO is binarized by a predetermined signal processing circuit and then decoded. The data is decoded by the circuit, and the data recorded on the optical disk 21 is reproduced by this.

Further, in the optical disc device 20, the subtraction circuit 9 outputs the target value signal S2 for the position detection signal S1 detected by the position sensor of the optical pickup 22.
An error signal is detected between the optical pickup and the phase compensation circuit 10 and the drive circuit 11, and the voice coil motor 12 of the sled motor is driven by the error signal through the phase compensation circuit 10 and the drive circuit 11, and the optical pickup has a profile determined by the target value signal S2. Seek 22 to the target track.

When the optical pickup 22 is sought in this way, the signal level of the tracking error signal and the total amount of the return light largely fluctuate each time the laser beam crosses the recording track. At this time, the return light is
As the light amount increases most at the timing of just tracking, as shown in FIG.
In FIG. 2 (B), the signal level becomes maximum at the timing of just tracking, and the tracking error signal TE crosses 0 level at the timing of just tracking according to the moving direction of the optical pickup 4. Will fall or rise (FIG. 2 (A)).

Therefore, in the optical disk device 20, by detecting the change in the signal level of the light amount detection signal PI or the tracking error signal TE, the moving speed and the positional change of the laser beam irradiation position on the optical disk 21 can be detected. Further, the moving direction of the laser beam irradiation position can be detected by detecting the phase relationship between the light amount detection signal PI and the tracking error signal TE.

Here, the displacement of the laser beam irradiation position is
The displacement of the laser beam irradiation position thus detected by the movement of the optical pickup 22 and the displacement of the objective lens 6 causes the optical pickup 2 to move.
By subtracting the displacement due to the movement of 2, only the component due to the displacement of the objective lens 6 can be detected. Therefore, if the voice coil motor 16 of the biaxial actuator is driven so that the component due to the displacement of the objective lens 6 becomes 0 level, the objective lens 6 can be held at a fixed position.

According to the principle of holding the objective lens 6, the optical disc device 20 has the tracking error signal TE and the light amount detection signal PI output from the matrix circuit 23.
Is supplied to the processing circuit 25, and binarized here to generate binarized signals STE and SPI (FIGS. 2C and 2D).

The up / down counter 26 receives the binarized signals STE and SPI, starts the seek operation, and receives the count command signal CONT from the control circuit, the binarized signals STE and SPI are used as a reference. Then, the operation is started, and thereby the count value that changes according to the displacement amount of the laser beam irradiation position is output.

That is, the up / down counter 26 resets the count value when the count command signal CONT is input, and then the tracking error occurs while the binarized signal SPI of the light amount detection signal PI is held at the H level. When the binarized signal STE of the signal TE rises, the count value is up-counted, and conversely, the light amount detection signal P
While the binary signal SPI of I is held at the H level, the binary signal STE of the tracking error signal TE is
When falls, the count value is down-counted.

As a result, the up / down counter 26
The count value rises when the laser beam irradiation position is displaced to the inner circumference side of the optical disk 21 across the recording track, and conversely, when the laser beam irradiation position is displaced to the outer circumference side of the optical disk 21 across the recording track. , And the count value is converted into an analog value by the digital-analog conversion circuit (D / A) 27 and output.

The subtraction circuit 29 is composed of an operational amplifier circuit, and inputs the position detection signal S1 to the non-inverting input terminal through the variable gain amplifier circuit 28 and outputs the output signal S5 of the digital-analog conversion circuit 27 to the inverting input terminal. Enter. Here, the variable gain amplifier circuit 28 has its gain adjusted in advance so that the component of the position detection signal S1 can be completely removed from the output signal S5 of the digital-analog conversion circuit 27.

As a result, as shown in FIG. 3, the signal level of the output signal S5 (FIG. 3B) of the digital-analog conversion circuit 27 changes smoothly according to the driving of the sled motor through the subtraction circuit 29. Position detection signal S1
The component shown in FIG. 3A is subtracted, and a subtraction signal S6 whose signal level changes according to the displacement of the objective lens 6 can be obtained. In FIG. 3, each signal is shown in a state where the vibration of the objective lens 6 is not regulated at all.

The phase compensation circuit 30 phase-compensates and outputs the subtraction signal S6 output from the subtraction circuit 29, and the drive circuit 15 outputs the voice of the biaxial actuator based on the output signal of the phase compensation circuit 30. The coil motor 16 is driven. As a result, in the optical disk device 20, the biaxial actuator is driven so that the signal level of the subtraction signal S6 is held at 0 level, and the objective lens 6 is held at the midpoint position of the movable range. Thus, when the seek is completed in this way, in the optical disc device 20, instead of the subtraction signal S6, the tracking error signal T
A servo loop is formed based on E to drive the biaxial actuator.

In the above structure, the return light from the optical disk 21 is condensed by the objective lens 6 and then received by the photodetector, and the photodetection result of this photodetector is subjected to current-voltage conversion processing in the matrix circuit 23 and then addition / subtraction processing. Then, the tracking error signal TE, the focus error signal FE, the reproduction signal MO, and the light amount detection signal PI are detected.

As a result, at the time of recording / reproducing, the optical disk device 2
In 0, the biaxial actuator is driven based on the tracking error signal TE and the focus error signal FE, and tracking control and focus control are performed. During recording, a modulation magnetic field is applied to the irradiation position of the laser beam, and desired data is thermomagnetic. In contrast to being recorded, during reproduction, a reproduction signal M
Based on O, the data recorded on the optical disc 21 is reproduced.

On the other hand, when seeking, the optical disk device 2
In the case of 0, the position of the optical pickup 22 is detected by the speed sensor mounted on the optical pickup 22, and the position detection signal S1 is subtracted from the target value signal S2 in the subtraction circuit 9. As a result, the voice coil motor 12 of the sled motor is driven so that the error signal resulting from the subtraction becomes 0 level, and the optical pickup 22 moves in a profile determined by the target value signal S2.

During this movement, the tracking error signal T
The E and the light amount detection signal PI are binarized by the processing circuit 25, and then up-counted or down-counted by the up-down counter 26, whereby positive or negative values are obtained according to the amount of displacement of the laser beam irradiation position. A changing count value is detected. This count value is converted into an analog signal by the digital-analog conversion circuit 27, and then the component of the position detection signal S1 is subtracted by the subtraction circuit 29, whereby a signal is generated according to the displacement of the objective lens 6 on the optical pickup 22. Subtraction signal S6 whose level changes
Is detected.

As a result, in the optical disk device 20, during seek, the voice coil motor 16 of the biaxial actuator is driven so that the subtraction signal S6 becomes 0 level instead of the tracking error signal TE, and the objective lens 6 moves. It is held at the center of the range, and the state of just tracking can be quickly formed immediately after seeking.

According to the above construction, the displacement of the laser beam irradiation position is detected on the basis of the received light of the return light, and the displacement of the entire optical pickup 22 is removed from the displacement detection result of the laser beam irradiation position. The displacement of the objective lens 6 on the optical pickup 22 can be detected by partially utilizing a conventional light receiving system without providing a position detecting mechanism such as a position detecting sensor. As a result, the biaxial actuator is driven so as to suppress the displacement of the objective lens 6 on the optical pickup 22, and the just tracking state can be quickly formed immediately after the seek with a simple configuration. The time required for access can be shortened.

Further, by omitting this kind of position detecting mechanism, the structure of the optical pickup 4 can be simplified, and the mass of the sled motor to be driven can be reduced to simplify the structure of the sled motor and the like. In addition, the reliability of the optical disc apparatus as a whole can be improved.

In the above embodiment, the case where the subtraction circuits 9 and 29 and the like are formed by analog signal processing circuits has been described, but the present invention is not limited to this, and the whole may be formed by digital signal processing circuits. Good.

Further, in the above embodiment, the case where the signals S1 and S5 are subtracted by the dimension of the displacement amount which is the position information has been described, but the present invention is not limited to this, and the displacement speed information of the laser beam irradiation position is described. It is also possible to remove the displacement velocity information component of the entire optical pickup 22 to generate a subtraction signal, and drive the biaxial actuator so that the subtraction signal becomes 0 level to hold the objective lens at the midpoint position.

Further, in the above embodiment, the case where the displacement information of the sled motor is subtracted from the displacement information of the laser beam irradiation position has been described, but the present invention is not limited to this, and the displacement information of the sled motor is replaced by the target. Value signal S
By subtracting 2, the displacement information of the sled motor may be equivalently subtracted from the displacement information of the laser beam irradiation position.

Further, in the above-mentioned embodiments, the case where the present invention is applied to the case of recording / reproducing data on / from the magneto-optical disk has been described, but the present invention is not limited to this, and a so-called write-once type optical disk apparatus, etc. It can be widely applied to various optical disk devices.

[0049]

As described above, according to the present invention, the displacement or displacement speed of the objective lens moving mechanism is subtracted from the displacement or displacement speed of the laser beam irradiation position detected from the return light, and the subtracted value is obtained. By suppressing the vibration of the objective lens based on the
It is possible to detect the displacement of the objective lens during seek, and to hold the objective lens at the movable center. By doing so, the objective lens position detection mechanism such as the position detection sensor can be omitted and the desired recording track can be accessed in a short time. It is possible to obtain an optical disk device that can do this.

[Brief description of drawings]

FIG. 1 is a block diagram showing an optical disc device according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation of the optical disk device of FIG.

FIG. 3 is a signal waveform diagram for explaining the signal processing of the optical disc device of FIG.

FIG. 4 is a block diagram showing a conventional optical disc device.

FIG. 5 is a signal waveform diagram for explaining the operation of the optical disc device of FIG.

[Explanation of symbols]

 1, 20 Optical disk device 2 Spindle motor 3, 21 Optical disk 4, 22 Optical pickup 6 Objective lens 9, 29 Subtraction circuit 10, 14, 30 Phase compensation circuit 11, 15 Drive circuit 12, 16 Voice coil motor 23 Matrix circuit 25 Processing circuit 26 Up-down counter 27 Digital-analog conversion circuit 28 Variable gain amplification circuit

Claims (2)

[Claims] 1. A light beam emitted from a light source is focused on a disc-shaped recording medium to record desired data, or a light beam emitted from a light source is collected on the disc-shaped recording medium. In an optical disk device for reproducing data recorded on the disc-shaped recording medium by illuminating, an objective lens for condensing the light beam on the disc-shaped recording medium and condensing return light obtained from the disc-shaped recording medium. A light receiving element that receives the return light condensed by the objective lens, an objective lens moving mechanism that moves the objective lens according to a predetermined drive signal, and the objective lens moving mechanism that moves the radius of the disc-shaped recording medium. In a radial direction of the disk-shaped recording medium, a position of the objective lens moving mechanism or a moving speed is detected to detect the seek speed. Position detecting means of the objective lens moving mechanism, which outputs the detection signal of 1., seek mechanism driving means which outputs the drive signal to drive the seek mechanism based on the first detection signal, and detection of the light receiving element. Position detecting means for the objective lens, which detects the position or movable speed of the objective lens in the radial direction of the disc-shaped recording medium based on a signal, and outputs a second detection signal; When the position or displacement speed of the objective lens with respect to the objective lens moving mechanism is detected based on the detection signal of, and the objective lens moving mechanism moves in the radial direction of the disk-shaped recording medium based on the detection result. ,
An optical disk device comprising: an objective lens moving mechanism driving means for driving the objective lens moving mechanism so as to hold the objective lens at a substantially movable center of the objective lens by the objective lens moving mechanism. 2. The position detecting means of the objective lens generates a tracking error signal from the output signal of the light receiving element and a light amount detection signal whose signal level changes according to the total light amount of the returning light, and the tracking error signal. The optical disk device according to claim 1, wherein the second detection signal is generated based on a signal and a light amount detection signal.