JP2000200429A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk realizing the appropriate focus jump even between two layers having unconstant distance there-between, in the reproduction of the optical disk wherein pieces of information are recorded on the plural layers. SOLUTION: On the inner periphery, intermediate periphery and outer periphery, etc., of the two-layer disk 1 of one-side reading DVD(digital video disk), focus error signals FE are preliminarily detected by a pickup 5, and these obtained distance data between two layers are stored in a RAM 19 through a DSP 15. In the focus jump for focusing the beam to the 2nd layer in the process of reproducing the 1st layer, the distance between two layers at the time of present reproduction is calculated by the DSP 15 based on the data preliminarily stored in the RAM 19, and by this result, the accelerating and decelerating pulses are supplied to a focus actuator 7 from a driver 23, thereby the appropriate control is realized for the pickup 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing (recording) an optical disk (Digital Video Disc-DVD) having a plurality of signal layers.

[0002]

2. Description of the Related Art FIG. 10 is a sectional view schematically showing the structure of a single-sided reading dual-layer disc.

As shown in FIG. 10, a two-layer disc is composed of a reflective recording layer B made of aluminum and having a reflectance of 70% or more, and a half-layer made of gold or the like and having a reflectance of about 30%. An ultraviolet curable resin having a thickness of about 40 μm is sandwiched between these two layers as an intermediate layer C.

Here, information as shown in FIG. 11 is recorded on the translucent recording layer A and the reflective recording layer B, respectively. That is, the information includes data and ID, and the ID includes an address (track number).
And layer information (layer number) and track information (track format information, area information, track method, reflectance).

[0005] Further, in this two-layer disc, one of the layers is semi-transparent, so that the laser beam (beam) can be seen from one side.
Is irradiated to focus each layer, so that information of the layer can be read through a pickup (PU).

[0006]

However, the above-mentioned 2)
In a multi-layer disc, the distance between the two layers is not practically uniform over the entire disc, which causes the following problems.

FIG. 12 is a sectional view showing the structure of a two-layer disc actually manufactured. This cross-sectional view shows a structure along a radius from the center to the outer periphery of a disk-shaped two-layer disc. As shown in FIG. 12, depending on the manufacturing method, the thickness of the ultraviolet curable resin (intermediate layer C) at the inner periphery is 40 μm, but the thickness increases toward the outer periphery and becomes 60 to 70 μm at the outer periphery. There is also a two-layer disc. Further, depending on the manufacturing method, the thickness of the intermediate layer C of the disc varies between 40 and 70 μm.

In a two-layer disc, the pickup may be moved to refocus the beam on the other layer and reproduce the other layer while reproducing one layer (this is called a focus jump). ).

Here, the pickup starts moving when an acceleration pulse is given to a focus actuator included therein, and the movement is stopped when a deceleration pulse is given.

FIG. 13 is a timing chart for explaining a conventional pickup control method in a focus jump.

As shown in FIG. 13, in the focus error signal FE (also called an S-shaped curve) shown in FIG.
A threshold value is set to the magnitude of the threshold value. At the point (or position) where the threshold value is exceeded, the signal supplied to the focus actuator of the pickup is changed from the acceleration pulse shown in FIG. Is switched to the deceleration pulse.

However, as described above, since the actual two-layer disc has a larger interlayer distance on the outer periphery than on the inner periphery, the switching point from the acceleration pulse to the deceleration pulse is far from the origin (at the time of reproducing the first layer). When the magnitude of the deceleration pulse is constant, the area A2 becomes smaller than the area A1.

Since the areas A1 and A2 correspond to the driving amount of the pickup, if the area A2 is smaller than the area A1, the pickup is not sufficiently stopped and runs away.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to provide an optical disk apparatus which realizes an appropriate focus jump in reproducing an optical disk in which the distance between two layers is not constant. With the goal.

[0015]

An optical disk device according to the present invention is a device for reproducing an optical disk having information recorded on a plurality of layers, by irradiating the optical disk with a beam and detecting the reflected light. The information reading means for reading information, the interlayer distance detecting means for detecting a first interval of a layer of the mounted optical disc at a plurality of points at different distances from the center of the optical disc, and the interlayer distance detecting means. Storage means for storing the first interval; and when the second layer is reproduced when the first layer of the optical disc is reproduced, the first layer for reproduction based on the first interval stored in the storage means. Control means for calculating a second distance between the second layer and the second layer, and controlling the information reading means to focus the beam on the second layer.

An optical disk device according to a second aspect is the optical disk device according to the first aspect, wherein the control means includes:
Further, an accelerating means for generating an acceleration signal for moving the information reading means so as to change the distance from the optical disk and supplying the accelerating signal to the information reading means, and an information accumulating means for positioning the beam on the second layer. A deceleration means for generating a deceleration signal having a variable size for stopping the reading means and supplying the generated signal to the information reading means.

An optical disk device according to a third aspect is the optical disk device according to the first aspect, wherein the control means includes:
Further, an acceleration means for generating an acceleration signal having a variable size for moving the information reading means so as to change the distance from the optical disk and supplying the acceleration signal to the information reading means, and focusing the beam on the second layer. And a deceleration means for generating a deceleration signal for stopping the information reading means at a position for supplying the information to the information reading means.

An optical disk apparatus according to a fourth aspect is the optical disk apparatus according to the first aspect, wherein the control means includes:
Further, an acceleration means for generating an acceleration signal having a variable size for moving the information reading means so as to change the distance from the optical disk and supplying the acceleration signal to the information reading means, and focusing the beam on the second layer. And a deceleration means for generating a deceleration signal having a variable size for stopping the information reading means at a position for supplying the information to the information reading means.

An optical disk device according to a fifth aspect is the optical disk device according to the first aspect, wherein the interlayer distance detection means obtains a focus error signal having two peaks having different polarities, and the control means Generates an acceleration signal for moving the information reading means so as to change the distance from the optical disk, supplies the acceleration signal to the information reading means, and sets the information reading means at a position for focusing the beam on the second layer. Is generated and supplied to the information reading means, and the acceleration signal supplied to the information reading means at any time between two peaks is switched to the deceleration signal.

According to a sixth aspect of the present invention, in the optical disk device of the first aspect, the interlayer distance detecting means obtains a focus error signal having two peaks having different polarities. The control means is
An acceleration signal for moving the information reading means so as to change the distance from the optical disc is supplied to the information reading means until an intermediate point between the two peaks, and is used for focusing the beam on the second layer. A deceleration signal for stopping the information reading means at the position is generated and supplied to the information reading means from an intermediate time.

According to a seventh aspect of the present invention, there is provided an optical disk apparatus for reproducing an optical disk having information recorded on a plurality of layers, wherein the information is read by irradiating the optical disk with a beam and detecting reflected light thereof. Means, an accelerating means for generating an acceleration signal for moving the information reading means so as to change the distance from the optical disk and supplying the accelerating signal to the information reading means, and information at a position for focusing the beam on a desired layer. And a deceleration means for generating a deceleration signal having a variable size for stopping the reading means and supplying the generated deceleration signal to the information reading means.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

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

As shown in FIG. 1, the optical disc apparatus includes a spindle motor 3 for rotating a single-sided read DVD double-layer disc (hereinafter, also simply referred to as a “double-layer disc”) 1 and a double-layer disc 1. A pickup (PU) 5 in which information recorded on the dual-layer disc 1 is read by irradiating a laser beam and detecting reflected light thereof, and a vertical distance to the double-layer disc 1 is controlled by a built-in focus actuator 7. A head amplifier 11 for amplifying a signal such as a focus error signal FE output from the pickup 5, and an A / A for converting an analog signal output from the head amplifier 11 into a digital signal.
A D / A conversion unit 13; a random access memory (RAM) 19 for storing information obtained from the dual-layer disc 1;
A digital signal processor (D) that stores information based on the digital signal output from the D conversion unit 13 in the RAM 19 and generates a digital signal specifying the position of the pickup 5 based on the information stored in the RAM 19.
SP) 15, a read-only memory (ROM) 17 in which a program for controlling the DSP 15 is stored, and a DSP
A D / A conversion unit 21 for converting a digital signal output from the D / A 15 into an analog signal, and an acceleration signal and a deceleration signal based on the signal output from the D / A conversion unit 21;
A driver 23 is provided for moving the pickup 5 by supplying an acceleration signal to the focus actuator 7 and for stopping the movement of the pickup 5 by supplying a deceleration signal to the focus actuator 7.

Next, the operation of the optical disk device according to the embodiment of the present invention will be described. First, this optical disk device detects a distance between two layers on which information is recorded at a plurality of points at different distances from the center in a mounted two-layer disk.

FIG. 2 is a diagram for explaining the detection of the distance between two layers. As shown in FIG.
Are sequentially moved, for example, to the inner circumference, the middle circumference, and the outer circumference of the single-side read DVD dual-layer disc 1, and detect the focus error signal FE at each point. Here, the distance (time) between the positive peaks P3 and P4 of the focus error signal FE.
Is larger at the outer periphery where the distance between the two layers is larger as shown in FIG.

The operation of detecting the distance between two layers will be specifically described below with reference to the flowchart of FIG.

First, in step S1, the type of the loaded optical disk is determined. Next, in step S2, the mounted optical disk is a double-layer digital video disk (D
(VD-Dual), and if it is DVD-Dual, the process proceeds to step S3.

In step S3, the pickup 5 is moved to the inner periphery of the two-layer disc 1, and in step S4, the laser beam is irradiated on the two-layer disc 1 while changing the distance between the pickup 5 and the two-layer disc 1, and the reflected light is measured. Start a focus search.

In step S5, the DSP 15 calculates the distance between the first layer and the second layer based on the focus error signal FE obtained by the measurement in step S4.

In step S6, the distance calculated by the DSP 15 is stored in the RAM 1 together with address information indicating the measurement position.
9 is stored (stored).

At step S7, the focus search is completed, and at step S8, the pickup 5 is moved to the center of the loaded two-layer disc 1.

In step S9, the operations in steps S4 to S7 are repeated while changing the measurement position, and in step S10, the pickup 5 is moved to the outer periphery of the loaded two-layer disc 1.

Hereinafter, steps S11 to S14
In, the operations from step S4 to step S7 are repeated again, and the routine for detecting the distance between the two layers on the outer periphery is ended in step S15.

As described above, the DSP 15 and the ROM 17 controlling the DSP 15 detect the distance between the two layers at a plurality of points at different distances from the center of the mounted two-layer disc 1.

The above description relates to the case where the distance between two layers is detected at three points on the inner circumference, the middle circumference, and the outer circumference of the two-layer disc 1. Table 1 below shows an example of specific information when the information is stored in the following table.

[0037]

[Table 1] In Table 1, the radius refers to the distance from the center of the mounted two-layer disc 1 to the measurement point of the distance between the two layers.

Next, a first example of a focus jump operation for reproducing the second layer while reproducing the first layer of the dual-layer disc 1 will be described with reference to the flowchart of FIG.

First, in step S1, the pickup 5
Layer information indicating the layer currently being played back, and an address (track number) indicating where the layer is currently being played back
Information is obtained from the dual-layer disc 1.

Next, in step S2, the DSP 15 calculates the interlayer distance at that position based on the address information by proportional distribution from the data previously stored in the RAM 19, and picks up the beam so as to focus the beam on the desired layer. The gain of each of the acceleration pulse for moving 5 and the deceleration pulse for stopping the movement is calculated.

In step S3, a digital signal is output from the DSP 15 to the D / A converter 21 based on the calculation result in step S2, and the driver 23 outputs an acceleration pulse having the gain calculated in step S2 to the pickup 5.
To the focus actuator 7.

In step S4, a change in the focus error signal FE accompanying the movement of the pickup 5 is measured, and it is determined whether or not the magnitude of the focus error signal FE exceeds a threshold.

Here, if it exceeds the threshold value, the process proceeds to the next step S5. In step S5, step S2
From the DSP 15 to the D / A converter 2 based on the calculation result
A digital signal is output to the pickup 1, and a deceleration pulse having the gain calculated in step S2 is given from the driver 23 to the focus actuator 7 of the pickup 5.

In the step S6, it is determined whether or not the focus error signal FE obtained by the pickup 5 becomes 0 level. Here, when a point (zero cross point) at which the focus error signal FE becomes 0 level is detected, the process proceeds to the next step S7, and the deceleration in the movement of the pickup 5 ends.

FIGS. 5 and 6 are diagrams for explaining focus jumps on the inner circumference and the outer circumference of the dual-layer disc 1, respectively.

As shown in FIG. 5, in the inner circumference of the dual-layer disc 1, the focus error signal FE is 20% of the difference (P6-P5) between two peak values of the focus error signal FE having different polarities. At a time (or position) T1 exceeding a threshold value set for the magnitude, the signal supplied to the focus actuator 7 is switched from the acceleration pulse to the deceleration pulse.

That is, in FIG. 5, an acceleration pulse is supplied to the focus actuator 7 from the origin to T1, and a deceleration pulse is supplied to the focus actuator 7 from T1 to T2. Here, the amplitudes of these two pulses are the same, and the area A3 and the area A4 corresponding to the driving amount of the pickup 5 are equal.

On the other hand, as shown in FIG. 6, on the outer periphery of the two-layer disc 1, the distance between the two layers on which information is recorded is larger than the inner periphery, so that the peak P5 of the focus error signal FE is increased. (Distance) from to P6
Becomes larger. Then, the time T3 at which the focus error signal FE exceeds the threshold value is also later than T1 shown in FIG.

Therefore, the acceleration pulse pickup 5
The area A5 corresponding to the driving amount with respect to the area A5 is the same as the case shown in FIG.
It becomes larger than 3. In this case, as in the case of the inner circumference shown in FIG. 5, a deceleration pulse having the same amplitude as the acceleration pulse is applied to the focus actuator 7 from T3 at which the focus error signal FE exceeds the threshold to zero cross point T4.
Is not supplied to the pickup 5 by the deceleration pulse as much as the amount of stop drive by the acceleration pulse. Thus, as shown in FIG. 6C, the gain of the deceleration pulse is increased to the size calculated by the DSP 15 so that the area A6 having the same size as the area A5 is formed between T3 and T4. . As a result, the pickup 5 accelerated by the acceleration pulse
Is reliably decelerated by the deceleration pulse and is appropriately stopped without runaway. Here, changing the magnitude of the deceleration pulse corresponds to changing the acceleration at which the pickup 5 is decelerated.

It is also conceivable to change the acceleration for accelerating the pickup 5 by changing the magnitude of the acceleration pulse.

Next, a second example of the focus jump operation will be described with reference to the flowchart of FIG.

As in the first example of the focus jump operation described above, in step S1, the current value address information and the layer information indicating the position where the pickup 5 is currently reproducing are obtained.

Next, in step S2, the DSP 15 uses the address information obtained by the
Based on the two-layer distance data stored in M19, an acceleration / deceleration switching point (hereinafter, also simply referred to as a "switching point") is calculated by proportional distribution. Here, the switching point refers to a point (position) at which a signal supplied to the focus actuator 7 is switched from an acceleration pulse to a deceleration pulse.
Specifically, it is set to the midpoint between two peaks having different polarities of the focus error signal FE obtained by calculation.

In step S3, an acceleration pulse is applied from the driver 23 to the focus actuator 7.

In step S4, it is determined whether or not the switching point has been reached after the start of the movement of the pickup 5, and if it has reached, the process proceeds to step S5.

In step S5, the supply of the acceleration pulse to the focus actuator 7 is stopped, and the deceleration pulse is supplied to the focus actuator 7 at the same time.

In step S6, it is detected whether or not the magnitude of the focus error signal FE has reached a set threshold value. If the magnitude has reached the threshold value, step S7 is reached.
Proceed to

In step S7, it is determined whether or not the magnitude of the focus error signal FE has become 0 again (a zero cross point is detected). When the zero cross point is detected, the supply of the deceleration pulse to the focus actuator 7 is terminated in step S8, and the pickup 5 is stopped.

FIGS. 8 and 9 are diagrams for explaining the focus jump operation on the inner circumference and the outer circumference of the dual-layer disc 1, respectively.

As shown in FIG. 8, the signal supplied to the focus actuator 7 at the intermediate time point T6 between the time points T5 and T7 where the focus error signal FE has two peaks P7 and P8 having different polarities is changed from an acceleration pulse to a deceleration pulse. The area A7 and the area A8 shown in FIGS. 8B and 8C are made equal. Also, as shown in FIG. 9, the focus error signal F
Except for the difference that the time (distance) T9 to T11 between two peaks P7 and P8 having different polarities in E becomes larger than the time (distance) T5 to T7 in the case of the inner circumference shown in FIG. Is similar.

That is, the signal supplied from the driver 23 to the focus actuator 7 is switched from the acceleration pulse to the deceleration pulse at an intermediate point T10 between the two peaks P7 and P8 having different polarities of the focus error signal FE.
The area A9 and the area A1 shown in (b) and (c), respectively.
0 is assumed to be equal.

The switching of the signal supplied from the driver 23 to the focus actuator 7 from the acceleration pulse to the deceleration pulse can be performed by appropriately changing the magnitude of the pulse so that the focus error signal FE has a different polarity.
It is likewise conceivable to take place at any time between the two peaks P7, P8.

The polarity of the acceleration or deceleration pulse in FIGS. 5, 6, 8, 9, and 13 and their descriptions is as follows.
This is determined by the moving direction of the pickup 5 with respect to the double-layer disc 1.

In the above description, the two-layer disc 1
It is needless to say that the above description can be similarly applied to a multilayer disc in which information is recorded in a plurality of layers.

[0065]

According to the optical disk device of the first aspect, in an optical disk in which information is recorded on a plurality of layers,
Even when the interlayer distance is not constant, refocusing (focus jump) for reproducing different layers can be properly realized.

According to the optical disk device according to the second to sixth aspects, the same effect as that of the invention according to the first aspect can be obtained, and runaway in the movement of the information reading means can be avoided.

According to the optical disk device of the seventh aspect,
The movement of the information reading means can be stopped at a variable speed.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining detection of a distance between two layers of an optical disc.

FIG. 3 is a flowchart illustrating an operation of detecting a distance between two layers of an optical disc.

FIG. 4 is a flowchart illustrating a first example of a focus jump operation.

FIG. 5 is a diagram for explaining a focus jump on the inner periphery of the two-layer disc in the operation shown in FIG. 4;

FIG. 6 is a diagram for explaining a focus jump on the outer periphery of the two-layer disc in the operation shown in FIG. 4;

FIG. 7 is a flowchart illustrating a second example of the focus jump operation.

FIG. 8 is a diagram for explaining a focus jump on the inner periphery of the two-layer disc in the operation shown in FIG. 7;

FIG. 9 is a diagram for explaining a focus jump on the outer periphery of the two-layer disc in the operation shown in FIG. 7;

FIG. 10 is a sectional view schematically showing the structure of a single-sided reading dual-layer disc.

11 is a diagram showing information recorded on the single-sided reading dual-layer disc shown in FIG.

FIG. 12 is a cross-sectional view showing the structure of an actually manufactured single-sided reading dual-layer disc.

FIG. 13 is a timing chart for explaining a pickup control method in a conventional focus jump.

[Explanation of symbols]

 5 Pickup (PU) 7 Focus Actuator 11 Head Amplifier 13 A / D Converter 15 Digital Signal Processor (DSP) 17 Read Only Memory (ROM) 19 Random Access Memory (RAM) 21 D / A Converter 23 Driver

Claims (7)

[Claims] 1. An apparatus for reproducing an optical disk having information recorded on a plurality of layers, comprising: an information reading means for irradiating a beam on the optical disk and detecting reflected light thereof to read the information; At different points from the center of
An interlayer distance detecting means for detecting a first interval between the layers of the mounted optical disc; a storage means for storing the first interval detected by the interlayer distance detecting means; a first layer of the optical disc When the reproduction of the second layer is performed at the time of reproduction, the second interval between the first layer and the second layer at the time of reproduction is set based on the first interval stored in the storage means. An optical disc device comprising: a control unit that calculates and controls the information reading unit so that the beam is focused on the second layer. 2. The control unit further includes: an acceleration unit that generates an acceleration signal for moving the information reading unit so as to change a distance from the optical disk and supplies the acceleration signal to the information reading unit; And a deceleration means for generating a deceleration signal having a variable size for stopping the information reading means at a position for focusing the beam on a layer of the first layer and supplying the deceleration signal to the information reading means. An optical disk device according to claim 1. 3. The acceleration means for generating an acceleration signal having a variable magnitude for moving the information reading means so as to change the distance from the optical disk and supplying the acceleration signal to the information reading means. And a deceleration means for generating a deceleration signal for stopping the information reading means at a position for focusing the beam on the second layer and supplying the deceleration signal to the information reading means. An optical disk device according to claim 1. 4. The acceleration means for generating an acceleration signal having a variable magnitude for moving the information reading means so as to change the distance from the optical disk and supplying the acceleration signal to the information reading means. And a deceleration means for generating a deceleration signal having a variable size for stopping the information reading means at a position for focusing the beam on the second layer and supplying the deceleration signal to the information reading means. The optical disk device according to claim 1, comprising: 5. The inter-layer distance detecting means obtains a focus error signal having two peaks having different polarities, and the control means moves the information reading means so as to change a distance from the optical disc. Signal to the information reading means, and the acceleration signal for the second
A deceleration signal for stopping the information reading means at a position for focusing the beam on a layer of the layer, and supplying the generated signal to the information reading means; 2. The optical disk device according to claim 1, wherein said acceleration signal supplied to said reading means is switched to said deceleration signal. 6. The inter-layer distance detecting means obtains a focus error signal having two peaks having different polarities, and the control means moves the information reading means so as to change a distance from the optical disk. And supplying the acceleration signal to the information reading means up to an intermediate point between the two peaks, and stopping the information reading means at a position for focusing the beam on the second layer. 2. The optical disk device according to claim 1, wherein a deceleration signal is generated and supplied to said information reading means from said intermediate time point. 7. An apparatus for reproducing an optical disk having information recorded on a plurality of layers, comprising: an information reading means for reading the information by irradiating a beam on the optical disk and detecting a reflected light thereof; Acceleration means for generating an acceleration signal for moving the reading means so as to change the distance from the optical disk and supplying the acceleration signal to the information reading means; and the information at a position for focusing the beam on a desired layer. An optical disc device comprising: a deceleration unit that generates a deceleration signal having a variable size for stopping the reading unit and supplies the deceleration signal to the information reading unit.