JPH10255276A - Optical disc device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce a requested recording layer quickly and without fail by a method wherein, if the transfer of the focus of an object lens is failed when a recording layer to be reproduced is changed while one of the recording layers of an optical disc having 2 or more recording layers on its one side is reproduced, a requested recording layer is identified from a focus error signal and focus servo is applied. SOLUTION: When a recording layer to be reproduced is changed, the focus of an object lens is transferred by the changeover of a switch 13. When the object lens is transferred by a signal which is generated in accordance with the detection of the change a focus error signal outputted by a preamplifier circuit 3, the switch 13 is so controlled as to be changed over to an actuator driver 9 side. If a focus signal following the transfer of the object lens is not obtained by the flaw of an optical disc 1, etc., and the transfer of the object lens is failed, the object lens is transferred downward and a focus error signal outputted by the preamplifier circuit 3 is detected and then the switch 13 is changed over to the actuator driver 9 side to detect a requested recording layer which is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital versatile disk (DVD)
The present invention relates to an apparatus for reproducing an optical disk having at least two recording layers.

[0002]

2. Description of the Related Art Conventionally, an LD (laser disk) or the like has been widely used as an optical disk having a plurality of recording layers. A disc such as an LD has one recording layer on each side, and in order to switch the recording layer to be reproduced, the mounted optical disc is generally inverted or replaced.

[0003]

However, recently, due to the increase in the capacity of computer data and the practical use of recording / reproducing digital moving picture information, optical discs of high density recording such as DVD are being standardized. Figure 1 in the DVD standard
There are four disks shown in FIG. Of these, in a disk having two recording layers on one side as shown in FIGS. 2 and 4, it is necessary to switch the recording layer to be reproduced as shown in FIG. When the focal point of the objective lens is moved from the recording layer currently being reproduced to another recording layer, the movement of the objective lens may fail due to a flaw or a surface shake depending on a disc. When the movement of the objective lens fails, it is sometimes impossible to return to the original position because the objective lens cannot be located. If time is spent on error processing when the movement of the objective lens fails in this way, for example, there is a possibility that a problem that an image stops during movie playback may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the optical disk apparatus and to ensure the processing when the movement of the objective lens fails quickly and reliably.

[0005]

In order to solve the above-mentioned problems, when the focus movement of the objective lens fails, a target recording layer is identified from a focus error signal and focus servo is applied there.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 6 is a block diagram showing an embodiment of the first invention of the present invention. Reference numeral 1 denotes an optical disk, and reference numeral 2 denotes a pickup that irradiates a laser beam onto the optical disk and converts reflected light into an electric signal. The signal output from the pickup 2 is amplified by the preamplifier circuit 3 and output. The signal processing circuit 4 performs known processing such as PLL and data slicing on the signal output from the preamplifier circuit 3 and outputs a video signal, an audio signal, and the like. Reference numeral 10 denotes a servo circuit, which is a motor driver 8 for driving a spindle motor 7 for rotating the optical disk 1 and an actuator driver 9 for driving the pickup 2.
Control. Reference numeral 12 denotes a focus moving circuit which controls movement of the objective lens of the pickup 2 in the thickness direction of the optical disk 1. Reference numeral 13 denotes a switch for switching the outputs of the actuator driver 9 and the focus moving circuit 12. Reference numeral 6 denotes an I / F circuit for processing an interface with an external device, and reference numeral 11 denotes a system control circuit.

In the above configuration, when the recording layer to be reproduced is switched, the switch 13 is switched to move the focal point of the objective lens. For example, the case where the objective lens is currently reproducing the recording layer indicated by the dotted line at the position shown in FIG. 7 and is going to move to the recording layer indicated by the solid line will be described. First, the switch 13 is used to move the objective lens. Is switched to the focus moving circuit 12 side, and the objective lens is moved to the position shown in FIG. At this time, the focus error signal output from the preamplifier circuit 3 changes as shown in FIG. When the change of the focus error signal is detected and the objective lens is moved to the position shown in FIG. 8 (FIG. 7), control is performed so that the switch 13 is switched to the actuator driver 9 side. However, depending on the optical disc 1, even if the objective lens is moved as shown in FIG.
8 cannot be obtained and the position shown in FIG. 8 (the position shown in FIG. 7) cannot be identified, and the movement of the objective lens may fail. In this case, the objective lens is moved downward from the position shown in FIG. 7, a focus error output from the preamplifier circuit 3 is detected, and when the objective lens is moved to the position shown in FIG. The control is switched to the actuator driver 9 side and the focus servo is started. When the movement of the objective lens fails as described above, the focus error signal output from the preamplifier circuit 3 is detected, and the processing is performed by focusing on the target recording layer. You can play the disc.

In the second embodiment of the present invention, when the movement of the objective lens in the first embodiment fails, it may not be possible to know the position of the objective lens in FIG. . In this case, the objective lens is once moved to the position shown in FIG.
The focus error signal output from the preamplifier circuit 3 is detected, and the switch 13 is switched to the actuator driver 9 side when the position of FIG. 8 (position of FIG. 7) is reached, and the focus servo is performed. Control to start. As described above, even when the movement of the objective lens fails and the position of the objective lens in FIG. 7 is not known, the focus error signal output from the preamplifier circuit 3 is detected, and the focus on the target recording layer is detected. The processing can be performed quickly and reliably even if the movement of the objective lens fails.

In the third embodiment of the present invention, the objective lens is moved to the position shown in FIG. 7 in a direction opposite to that of the second embodiment, and the objective lens shown in FIG. By moving the objective lens as described above, the focus error signal output from the preamplifier circuit 3 is detected. When the focus error signal reaches the position shown in FIG. 8 (the position shown in FIG. 7), the switch 13 is switched to the actuator driver 9 side, and the focus servo is performed. Activating also allows the target recording layer to be similarly focused. As described above, when the movement of the objective lens fails and the position of the objective lens in FIG. 7 is not known, the focus error signal output from the preamplifier circuit 3 is detected, and the focus is focused on the target recording layer. By performing the processing, it is possible to quickly and surely reproduce the disc even if the movement of the objective lens fails.

FIG. 9 is a block diagram showing a fourth embodiment of the present invention. Reference numeral 14 denotes a switch for switching the rotation speed of the spindle motor between high speed rotation and low speed rotation. Other configurations are the same as those in FIG. 6 and are denoted by the same reference numerals as in FIG.

In the above configuration, when the recording layer to be reproduced is switched, the switch 13 is switched to move the focal point of the objective lens. For example, a case where the objective lens is currently positioned in FIG. 7 and is reproducing the recording layer indicated by the dotted line, and is going to move to the recording layer indicated by the solid line will be described. 13 is switched to the focus moving circuit 12 side, and the objective lens is moved to in FIG. At this time, the focus error signal output from the preamplifier circuit 3 changes as shown in FIG. When the change of the focus error signal is detected and the objective lens is moved to the position shown in FIG. 8 (FIG. 7), control is performed so that the switch 13 is switched to the actuator driver 9 side. However, depending on the optical disk 1, the surface runout may be large and the movement of the objective lens may fail. When the rotation speed of the disk is large and the rotation speed of the disk is large, for example, as shown in FIG. 10, the displacement amount ΔX2 of the recording layer becomes large during the period Δt. Therefore, even if the switch 13 is switched to the actuator driver 9 at the position shown in FIG. 8 (the position shown in FIG. 7), the focus servo is not applied, and the movement of the objective lens may fail. In this case, the switch 14 is switched from the high-speed rotation to the low-speed rotation so that the rotation speed of the optical disc 1 is made slower than when the movement of the objective lens fails, and the target solid recording layer is formed in the same manner as in the above embodiment. Control to give focus. When the rotation speed of the optical disk is reduced, the displacement amount ΔX1 of the recording layer becomes smaller than ΔX2 as shown in FIG.
Switching the switch 13 to the actuator driver 9 at the position shown in FIG. 8 (the position shown in FIG. 7) reduces the possibility that focus servo is not applied. When the movement of the objective lens fails in this way, the rotation speed of the optical disk is made slower than when the movement of the objective lens fails, and the target solid-layer recording layer is processed by applying focus servo to the movement of the objective lens. Even if it fails, it is possible to play the disc quickly and reliably.

In the fifth embodiment of the present invention, when the movement of the objective lens fails, the focus error signal output from the preamplifier circuit 3 is detected, and the layer before the movement of the objective lens is identified. Then, the switch 13 is switched to the actuator driver 9 side to apply the focus servo. Thereafter, the switch 14 is switched from the high-speed rotation to the low-speed rotation, and control is performed so that the objective lens is moved again. When the rotation speed of the optical disk is reduced, the displacement amount ΔX1 of the recording layer becomes smaller than ΔX2 as shown in FIG. 10, so that the failure in moving the objective lens is reduced. As described above, if the movement of the objective lens fails, focus servo is applied to the recording layer that was being reproduced before the failure, and then the rotation speed of the optical disc is made slower than when the movement of the objective lens failed, and the target recording is performed. By performing the processing for moving the objective lens to the layer, even if the movement of the objective lens fails, the disk can be reproduced quickly and reliably.

[0014]

According to the present invention, when the recording layer is switched during reproduction of an optical disk having two or more recording layers on one side, as represented by a DVD, even if the movement of the objective lens fails, The target recording layer can be reproduced quickly and reliably.

[Brief description of the drawings]

FIG. 1 is an example of a DVD disk.

FIG. 2 is an example of a DVD disk.

FIG. 3 is an example of a DVD disk.

FIG. 4 is an example of a DVD disk.

FIG. 5 is a diagram showing movement of an objective lens between recording layers.

FIG. 6 is a block diagram showing a configuration of the first, second, and third aspects of the present invention.

FIG. 7 is a diagram showing movement of an objective lens.

FIG. 8 is a diagram showing a focus error signal when an objective lens is moved.

FIG. 9 is a block diagram showing a configuration of the fourth and fifth aspects of the present invention.

FIG. 10 is a diagram showing displacement of a recording layer in a surface wobble disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Pickup 3 ... Preamplifier circuit 4 ... Signal processing circuit 6 ... I / F circuit 7 ... Spindle motor 8 ... Motor driver 9 ... Actuator driver 10 ... Servo circuit 11 ... System control circuit 12 ... Focus movement circuit 13 ... Switch 14 ... Switch

Claims (5)

[Claims] A pickup for injecting a laser beam into the optical disc and converting reflected light into an electric signal; an objective lens moving circuit for moving an objective lens of the pickup in a thickness direction of the mounted optical disc; An optical disk device including a preamplifier circuit for generating and outputting a focus error signal from an output signal, wherein when the focus of the objective lens has failed to move from the recording layer being reproduced to another layer, the preamplifier An optical disc device wherein a target layer is identified from a focus error signal output from a circuit and focus servo is applied. 2. The optical disk device according to claim 1, wherein, when the movement of the objective lens fails, the objective lens is moved to a side away from the disk in the thickness direction of the mounted disk, and An optical disk device, wherein the objective lens is moved toward the disk, a target layer is detected based on a focus error signal output from the preamplifier circuit, and focus servo is applied. 3. The optical disk device according to claim 1, wherein when the movement of the objective lens fails, the objective lens is moved to a side approaching the disk in a thickness direction of the mounted disk, and from there. An optical disk device, wherein the objective lens is moved to a side away from the disk, a target layer is detected based on a focus error signal output from the preamplifier circuit, and focus servo is applied. 4. The preamplifier circuit according to claim 1, wherein when the movement of the objective lens fails, the rotation speed of the mounted optical disk is reduced from the rotation speed at the time of the failure. An optical disc apparatus characterized in that a target layer is identified from a focus error signal output by the controller and focus servo is performed. 5. A pickup for injecting a laser beam into an optical disc and converting reflected light into an electric signal; an objective lens moving circuit for moving an objective lens of the pickup in a thickness direction of the mounted optical disc; An optical disc apparatus comprising: a preamplifier circuit for generating and outputting a focus error signal from an output signal; when the focus of the objective lens cannot be moved from the recording layer being reproduced to another layer, The focus servo is performed by identifying the layer before moving the objective lens from the focus error signal output from the circuit, and the rotation speed of the mounted optical disc is decreased from the rotation speed at the time when the movement failed, and then the objective lens is again moved. An optical disk device that performs movement.