JP3994621B2 - Optical disk drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk drive device that can move a focal point from a recording or reproducing layer to another layer in an optical disk having a plurality of layers capable of recording or reproducing information.
[0002]
[Prior art]
Conventionally, an optical disk device described in Japanese Patent Application Laid-Open No. 08-171731 is known.
[0003]
FIG. 2 shows a block diagram of a conventional optical disk drive. In FIG. 2, 11 is an optical disc having a plurality of layers capable of recording or reproducing information, 12 is a light beam applied to the layer of the optical disc 11, and the amount of focus deviation between the layer and the light beam is focused. An optical pickup that detects an error signal, 13 is a compensation circuit that generates a focus adjustment signal from the focus error signal, 14 is a focus drive circuit that drives the objective lens of the optical pickup 12 using the focus adjustment signal, and 15 is an optical signal. In order to move the focus of the light beam by the objective lens of the optical pickup 12 to another layer, a movement signal generating circuit for giving an acceleration signal and a deceleration signal to the focus drive circuit 14, and 17 is a focus error signal from the current layer and the target layer It is detected that a predetermined position in the middle position or near the middle position has been reached, and An intermediate-target layer detection circuit for detecting that has reached the position. 18 selects a signal on the side of the compensation circuit 13 during recording or reproduction, and a signal of the sum of the signal of the compensation circuit 13 and the movement signal generation circuit 15 by the adder 20 during focus movement to another layer. This is a switching circuit that switches a signal that is selected and applied to the focus driving circuit 14. Reference numeral 19 denotes a focus control circuit that controls the procedure so that the focal position in the recording or reproducing state is moved to another layer, and the recording state or reproducing state is set again in another layer.
[0004]
In such an optical disk drive, first, the focus circuit starts from the recording or reproduction state, so that the switching circuit 18 switches the input from the compensation circuit 13 side to the movement signal generation circuit 15 side. Next, during a period from the start of focus movement until the intermediate / target layer detection circuit 17 detects the intermediate position, the movement signal generation circuit 15 generates an acceleration signal having a predetermined magnitude in the target direction. Next, during a period from when the intermediate / target layer detection circuit 17 detects the intermediate position to when the target layer is detected, the movement signal generation circuit 15 generates a deceleration signal having a predetermined magnitude in the opposite direction of the acceleration signal. Finally, the switching circuit 18 switches the input from the movement signal generation circuit 15 side to the compensation circuit 13 side in order to change the focus movement state to the recording or reproduction state. The above procedure is controlled by the focus control circuit 19.
[0005]
[Problems to be solved by the invention]
However, in the configuration of such a conventional optical disk drive device, acceleration / deceleration of the beam focus by the focus servo system is performed based on the S-shaped waveform of the focus error signal, so that appropriate acceleration and deceleration are performed. For this purpose, the S-shaped waveform of the focus error signal between the current layer and the target layer is required to have accurate symmetry.
[0006]
In general, the S-shaped waveform of the focus error signal easily loses symmetry due to variations in the optical disc, more specifically, variations in the reflectivity between the current layer and the target layer, and variations in the distance between the current layer and the target layer. End up.
[0007]
Further, since the optical pickup is usually designed so that the focus error signal waveform in the vicinity of the layer is suitable for focus adjustment, the S-shaped waveform of the focus error signal between layers is not suitable for detecting the intermediate position. There are many cases.
[0008]
Assuming that one part (for example, the previous part) of the S-shaped waveform has a low amplitude and a wide time width, and the other part (the same part and the subsequent part) has a large amplitude and a narrow time width, When the waveform is not point-symmetric, the maximum value, the amount of change (slope), and time during acceleration and deceleration are different before and after. For this reason, the acceleration / deceleration amount required for the movement from the current layer to the target layer is excessive or insufficient, thereby causing inconveniences such as not reaching the target layer or passing through the target layer at a high speed, The focus pulling operation to the target layer becomes unstable.
[0009]
An object of the present invention is to provide an optical disk drive in which the stability of focal movement is not affected by the symmetry of the focus error signal between layers.
[0010]
[Means for Solving the Problems]
In order to solve this problem, an optical disk drive apparatus according to the present invention includes a moving signal generating means for giving an acceleration signal and a deceleration signal to a focus driving means for moving a focus to another layer, and a focus during recording or reproduction. A shake speed detecting means for detecting the direction and speed of the optical disc shake in the focus adjustment direction from the rate of change of the low frequency component of the error signal, and the amount of deviation between the target layer and the focus is zero or near zero from the focus error signal. A target layer detecting means for detecting that a predetermined position has been reached is provided, and the acceleration signal is adjusted according to the shake speed with respect to the predetermined magnitude in the target direction to determine the direction and magnitude, and the deceleration signal is the target magnitude. When the layer detecting means detects the arrival at the predetermined position, it is set to the same or a predetermined size in the reverse direction of the acceleration signal.
[0011]
This makes it possible to appropriately accelerate and decelerate the focus movement stability without being affected by the symmetry of the focus error signal between layers.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, there is provided an optical disc driving apparatus having a plurality of layers capable of recording or reproducing information, wherein the optical disc detects an amount of defocus between the layer and a light beam as a focus error signal. An optical pickup, a compensation means for generating a focus adjustment signal from the focus error signal, a focus drive means for driving the objective lens of the optical pickup using the focus adjustment signal, and for moving the focus to another layer A moving signal generating means for providing an acceleration signal to the focus driving means, and detecting the direction and speed of the deflection of the optical disc in the focus adjustment direction from the rate of change of the low frequency component of the focus error signal during recording or reproduction. And the acceleration signal is adjusted according to the shake speed, thereby causing a focus error signal between layers. Be asymmetric accelerated in response to deflection of the optical disc, it has the effect of allowing the focus movement in the stable another layer.
[0013]
According to a second aspect of the present invention, there is provided target layer detection means for detecting that the amount of deviation between the target layer and the focal point has reached zero or a predetermined position near zero based on the focus error signal, and the target layer detection means is predetermined. When the movement signal generating means detects arrival at a position, the movement signal generating means generates a deceleration signal having the same or a predetermined magnitude in the reverse direction of the acceleration signal determined in accordance with the shake speed, thereby enabling the focus between layers. Even if the error signal is asymmetric, it has a function of decelerating in response to the shake of the optical disk and allowing the focal point to be stably moved to another layer.
[0014]
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
[0015]
(Embodiment 1)
FIG. 1 is a block diagram of an optical disk drive apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is an optical disc having a plurality of layers capable of recording or reproducing information, 2 is a layer of the optical disc 1 that is irradiated with a light beam, and the amount of defocus between the layer and the light beam is a focus error. An optical pickup to be detected as a signal, 3 is a compensation circuit that generates a focus adjustment signal from the focus error signal, 4 is a focus drive circuit that drives the objective lens of the optical pickup 2 using the focus adjustment signal, and 5 is a focus. A moving signal generating circuit for giving an acceleration signal and a decelerating signal to the focus driving circuit 4 for moving to another layer, 6 is an optical disk in the focus adjustment direction from the rate of change of the low frequency component of the focus error signal during recording or reproduction 1 is a shake speed detection circuit that detects the direction and speed of 1 shake, and 7 is a predetermined error in which the amount of deviation between the target layer and the focus is zero or near zero based on the focus error signal. A target layer detection circuit for detecting that reached location. 8 selects the signal on the compensation circuit 3 side during recording or reproduction, and selects the sum signal of the signal from the compensation circuit 3 and the movement signal generation circuit 5 by the adder 10 during focus movement to another layer. A switching circuit 9 for switching a signal to be supplied to the focus driving circuit 4 is a focus control circuit for controlling a procedure for moving the focal position in the recording or reproducing state to another layer and setting the recording or reproducing state again in another layer.
[0016]
The operation of the optical disk drive configured as described above will be described below.
[0017]
First, in order to start focus movement from the recording or reproduction state, the switching circuit 8 switches the input from the compensation circuit 3 side to the movement signal generation circuit 5 side. Next, the movement signal generation circuit 5 determines the direction and magnitude by increasing or decreasing the predetermined magnitude in the target direction according to the shake speed detected by the shake speed detection circuit 6, and generates a pulse-like acceleration signal. appear. When the target layer detection circuit 7 detects the arrival at a predetermined position after the focal point starts moving toward the target layer, the movement signal generation circuit 5 is the same or predetermined in the reverse direction of the acceleration signal determined according to the shake speed. A double pulse-like deceleration signal is generated. Finally, the switching circuit 8 switches the input from the movement signal generation circuit 5 side to the compensation circuit 3 side in order to change the focus movement state to the recording or reproduction state. The above procedure is controlled by the focus control circuit 9.
[0018]
Since the compensation circuit 3 extracts the low frequency component of the focus error signal to generate the focus adjustment signal from the focus error signal, the shake speed detection circuit 6 differentiates the low frequency component output from the correction circuit 3. And detect direction and speed. The acceleration signal and the deceleration signal of the movement signal generating circuit means 5 are superimposed on the low frequency component output from the correction circuit 3 and input to the switching circuit 8.
[0019]
As described above, according to the present embodiment, even if the S-shaped focus error signal between the layers is asymmetrical, the optical disk is accelerated and decelerated in response to the shake of the optical disk, and the focus is moved to a stable different layer. It will be possible.
[0020]
【The invention's effect】
As described above, according to the present invention, even if the S-shaped focus error signal between the layers is asymmetric, the optical disk is accelerated and decelerated in response to the shake of the optical disk, thereby enabling stable focus movement to another layer. An advantageous effect is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram of an optical disk drive device according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional optical disk drive device.
DESCRIPTION OF SYMBOLS 1 Optical disc 2 Optical pick-up 3 Compensation circuit 4 Focus drive circuit 5 Movement signal generation circuit 6 Speed detection circuit 7 Target layer detection circuit 8 Switching circuit 9 Focus control circuit 10 Adder

Claims (2)

A drive device for recording or reproducing an optical disc having a plurality of layers capable of recording or reproducing information by irradiating the layer with a light beam,
An optical pickup that detects a defocus amount of the layer and the light beam as a focus error signal; a compensation unit that generates a focus adjustment signal from the focus error signal; and the optical pickup using the focus adjustment signal. Focus drive means for driving the objective lens, movement signal generating means for giving an acceleration signal to the focus drive means for moving the focus to another layer, and change in the low frequency component of the focus error signal during recording or reproduction A shake speed detecting means for detecting the direction and speed of shake of the optical disc in the focus adjustment direction from the rate,
The optical disk drive apparatus according to claim 1, wherein the acceleration signal is adjusted in accordance with the shake speed with respect to a predetermined magnitude in a target direction to determine an acceleration direction and magnitude. A target layer detecting means for detecting that the amount of deviation between the target layer and the focal point has reached zero or a predetermined position near zero from the focus error signal, and when the target layer detecting means detects the arrival at the predetermined position, 2. The optical disk drive according to claim 1, wherein the movement signal generating means generates a deceleration signal having the same or a predetermined magnitude in the reverse direction of the acceleration signal determined in accordance with the shake speed. .

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