JPH05282680A - Optical disk device - Google Patents

Abstract

PURPOSE:To enable an accurate control by generating an offset signal according to the magnitude of power applied from outside to a slider and making a slider servo control while adding the offset signal to a detection signal detected by a position sensor. CONSTITUTION:An optical system converging the light beam to an optical disk 10 is provided to perform read and write of data on the disk 10. Further, an optical axis deviation detection means detecting the deviation between an objective lens 1 and the optical axis of the laser beam as a position error signal by a position sensor 4 is provided. According to the detected position error signal, the optical system is moved in the radial direction of the optical disk 10 to control a slider 9 and to correct the optical axis deviation. An offset signal generation means generating an offset signal according to the magnitude of power applied from outside to the slider 9 and an error signal generation circuit generating a position error signal by adding the offset signal and the detection signal detected by the position sensor 4 are also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device for recording or reproducing information on an optical information recording medium, and more particularly to an optical disc device for accurate recording or reproduction.

[0002]

2. Description of the Related Art An optical disk device includes a laser diode as a recording / reproducing light source, and irradiates an optical information recording medium with laser light emitted from the laser diode to record and reproduce information on the optical information recording medium. It is a thing.

In this type of device, the laser light from the laser diode is focused by an objective lens. And
The objective lens is controlled to move up and down so as to focus on the recording surface of the disc following the rotation of the disc.
Further, track servo is performed to move the objective lens left and right so as to always follow the groove formed on the recording surface of the disc.

A slider (in the case of a separation optical system, only a rising mirror is included; in other cases, an optical system is included)
Was moved so as to follow the objective lens, and the optical axis of the objective lens and the laser beam were aligned.

A sensor for detecting the deviation between the objective lens and the optical axis of the laser light is called a position sensor, and a signal obtained from this position sensor is called a position error signal (PE signal).

A method of detecting the position error signal will be described with reference to FIG.

An LED 3 is mounted in a direction perpendicular to the optical axis of an objective lens holder 2 that holds the objective lens 1. Then, a two-divided photodetector is arranged to receive light from the LED 3. Then, the output of the two-divided photodetector is differentially amplified by the differential amplifier circuit. In this case, when the optical axis center of the objective lens coincides with the optical axis from the laser diode, the position error signal output from the differential amplifier circuit is adjusted to 0.

In this case, the relationship between the position of the objective lens with respect to the laser optical axis and the position error signal is as shown in FIG. Then, servo is applied by this position error signal to match the optical axes.

FIG. 5 is a configuration diagram showing a configuration for aligning the objective lens 1 and the optical axis of the laser light by moving the slider 9. In this figure, the slider 9 is configured to be movable in the radial direction of the disk, and is controlled by a slider servo control system (not shown) in accordance with the recording / reproducing track. The objective lens 2 is controlled by a track control servo system (not shown), and is configured to move independently on the slider 9 in order to accurately trace a target track on the rotating disk 10.

A position sensor 4 which receives a light beam from an LED 3 mounted on the objective lens holder 2
The output of is differentially amplified by the differential amplifier circuit 5 to extract the position error signal, and the low pass filter 6 limits the position error signal to a signal of only the required band. Then, the phase compensation filter 7 compensates the phase required for servo, the current amplifier 8 amplifies the current, and a drive current is applied to the slider 9. The slider 9 is generally driven by a voice coil type motor.

[0011]

In order to drive the actuator mounted on the slider 9 and the slider 9, electric power is supplied through a flexible printed circuit board (FPC). In this case, use slider 9 as much as possible.
However, it is inevitable that a certain amount of force is applied to the slider 9 from the FPC.

FIG. 6 is a diagram showing a force applied to the slider 9 from the FPC. As shown in this figure, the force received from the FPC varies depending on the position of the slider 9. Further, due to this force, the slider 9 cannot be accurately stopped at the target position.

Therefore, a deviation occurs in the position of the slider 9 as shown in FIG. This deviation causes an optical axis shift between the objective lens and the laser light.

This deviation adversely affects the operations of the focus servo and track servo.

The present invention has been made paying attention to such a point, and an object thereof is an optical disk capable of preventing the optical axis shift between the objective lens and the laser beam and performing reliable focus and track control. To provide a device.

[0016]

Means for solving the above-mentioned problems include an optical system for converging a light beam on an optical disk,
In addition to reading or writing data on the optical disc, the optical axis deviation detecting means for detecting the deviation of the optical axis between the objective lens and the laser light as a position error signal by the position sensor is provided, and the position error signal is detected according to the detected position error signal. Then, in the optical disk device equipped with the control means for correcting the optical axis shift by controlling the slider servo that moves the optical system in the radial direction of the optical disk, an offset signal is generated according to the magnitude of the force that the slider receives from the outside. And a position error signal generating circuit for generating a position error signal by adding the offset signal and the detection signal detected by the position sensor.

[0017]

In the present invention, the position error signal is generated by adding the detection signal detected by the position sensor and the offset signal generated by the offset signal generating means. In this case, the slider servo control is performed in a state where the force applied to the slider from the outside by the position of the slider is canceled by the offset signal generated by the offset signal generating means. Therefore, the optical axes of the objective lens and the laser diode coincide with each other.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. The same parts as those in FIG.

In this figure, laser light from a laser diode (not shown) attached to the slider 9 is focused on the recording surface of the disk 10 by the objective lens 2. Then, the light reflected by the disk 10 passes through the objective lens 2 again and is processed by a reading optical system (not shown). Here, the objective lens 2 is driven by a track servo control system (not shown) and moves on the slider 9 in a minute range. This movement causes a shift of the optical axis, which is detected by the position sensor 4.

When the slider 9 moves on a track,
A / D conversion of the detection output of the position sensor 4 to the CPU
14 reads. The CPU 14 sends the PE signal and the slider 9
The relationship with the force received by is stored by an arithmetic expression or a table, and a necessary offset is generated according to the PE signal. After that, the offset continues to be generated until the track is moved. The offset generated by the CPU 14 is D / A converted by the D / A converter 15, and the adder 1
At 2, the output of the position sensor 4 is added. And
Slider servo control is executed. Thus, the slider 9 is added to the output of the position sensor with an offset capable of counteracting the force from the FPC, and the slider servo is executed. Can be moved to, and accurate slider servo control is executed. Therefore, the optical axis deviation is surely corrected. As a result, the focus servo and the track servo are not adversely affected.

Further, in addition to obtaining the offset each time it moves to each track as described above, it is also possible to move the slider 9 to all the tracks in advance and have the CPU 14 obtain the necessary offset for each track from the PE signal. Is.

When the relationship between the position of the slider 9 and the required offset amount is known, a table 16 having data on the relationship between the position of the slider 9 and the offset amount is prepared as shown in FIG. .. Then, a necessary offset is output by giving a signal indicating the position of the slider to this table. The output of this table 16 is D
The A / A converter 17 performs D / A conversion, and the adder 12 adds it to the output of the position sensor 4. Also in this case, the same effect as the embodiment shown in FIG. 1 can be obtained.

[0024]

As described in detail above, according to the present invention, an offset signal is generated according to the magnitude of the force applied to the slider from the outside, and the offset signal and the detection signal detected by the position sensor are added. Since the slider servo control is performed by using the slider servo control, accurate control is possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram showing how an optical axis shift is detected.

FIG. 4 is an explanatory diagram showing a relationship between an optical axis shift and a PE signal.

FIG. 5 is an explanatory diagram showing an overall configuration of a conventional device.

FIG. 6 is an explanatory diagram showing a relationship between a disc position and a force received from an FPC.

FIG. 7 is an explanatory diagram showing a relationship between a disc position and a PE signal.

[Explanation of symbols]

 1 Objective Lens 4 Position Sensor 6 Low Pass Filter 7 Phase Compensation Filter 8 Current Amplifier 9 Slider 10 Disk 11 Spindle Motor 12 Adder 13 A / D Converter 14 CPU 15 D / A Converter

Claims (1)

[Claims] 1. An optical system for converging a light beam on an optical disc, for reading or writing data on the optical disc, and using a position sensor as a position error signal for a deviation of an optical axis between an objective lens and a laser beam. An optical disc apparatus including an optical axis deviation detecting means for detecting, and controlling means for a slider servo for moving an optical system in a radial direction of the optical disk according to the detected position error signal, and a control means for correcting the optical axis deviation. In (1), a position error signal for generating a position error signal by adding an offset signal generating means for generating an offset signal according to the magnitude of a force received by the slider from the outside and a detection signal detected by the position sensor An optical disk device comprising a generation circuit.