JP2000200428A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk device capable of reducing the access time by simultaneously performing the focus jump and the seek to an objective address. SOLUTION: When the information of the objective address and layer are given from the outside, the moving amount to the objective address is calculated by a DSP(digital signal processor) 6 and the corresponded PWM signal is outputted, and this PWM signal is integrated by an integrator 11 to form a thread driving signal, then a pickup 3 is moved to the vicinity of the objective address by a feeding mechanism 13. At the same time, a focus error signal FE is outputted by the DSP 6, and the pickup 3 is subjected to focus jump from the 1st layer to the 2nd layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive, and more particularly, to an optical disk (Digita) having a plurality of signal layers.
l Video Disc: It relates to a video disc device for reproducing information from a DVD or recording information.

[0002]

2. Description of the Related Art A CD-ROM is an optical disk having a thickness of about 1.2 mm, from which information is read using a semiconductor laser. In this optical disk, a signal is reproduced by irradiating a laser beam to a pit row on a signal recording surface by performing focus servo and tracking servo on a pickup objective lens. Recently, the recording density for recording a long moving image has been increasing.

For example, the diameter 12c is the same as that of a CD-ROM.
A DVD standard for recording 4.7 Gbyte information on one side of an m optical disk has been proposed. The disc thickness of the DVD is about 0.6 mm, and a two-layer disc can be formed by laminating the discs on both sides.
9.4 Gbytes of information can be recorded on one sheet. In order to reproduce a two-layer optical disk having two signal recording surfaces, a method of reproducing two signal recording surfaces from one surface of the disk,
A method of reproducing one signal recording surface from each side of the disk can be considered. However, the method of reproducing one signal recording surface from both surfaces is complicated since it is necessary to turn over the disc when reproducing another signal recording surface after the reproduction of one signal recording surface is completed. . Also,
While one signal recording surface is being reproduced, the other signal recording surface cannot be reproduced. For this reason, a method of reproducing two signal recording surfaces from one surface has become mainstream.

FIG. 6 is a sectional view schematically showing the structure of a single-sided reading dual-layer disc. As shown in FIG. 6, the two-layer disc has a reflective recording layer B made of aluminum and having a reflectance of 70% or more, and a translucent recording layer made of a material such as gold and having a reflectivity of about 30%. A, and an ultraviolet curable resin having a thickness of about 40 μm is sandwiched between these two layers as an intermediate layer.

In this two-layer disc, one of the layers is of a translucent type, so that a laser beam (beam) is
And focus on each layer, the information of that layer can be read through the pickup (PU).

In a two-layer disc, a so-called focus jump is performed in which a beam is refocused on the other layer while reproducing one layer, and the pickup is moved to reproduce the other layer. .
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. 7 is a diagram for explaining a conventional pickup jump control method. In the focus error signal FE (also called an S-curve signal) shown in FIG.
A threshold value is set to 20% of the value of 1), and at a point (or position) exceeding the threshold value, a signal supplied to the focus actuator of the pickup is shown in FIG.
Is switched from the acceleration pulse shown in FIG. 7 to the deceleration pulse shown in FIG.

[0008]

By the way, in the conventional optical disk device, when an address of a target destination and target layer information are given, first, a focus jump from a current layer to a target layer is performed. Control is performed so that a target address is sought by a pickup feed mechanism.

[0009] However, since DVDs are capable of high-density recording, they are likely to be used as computer memories in the future, and it is necessary to access target addresses as soon as possible. However, in the conventional method, since the control is performed so as to seek the target address after the focus jump, there is a problem that the access time becomes long.

[0010] Therefore, a main object of the present invention is to provide an optical disc apparatus capable of simultaneously shortening an access time by performing a focus jump and a seek to a target address.

[0011]

According to the present invention, there is provided an optical disc apparatus for reproducing an optical disc having information recorded on a plurality of signal recording surfaces of a plurality of layers. Information reading means for reading out information by detection, driving means for moving the information reading means along the signal recording surface, and information reading means for focusing on one of the signal recording surfaces of the plurality of layers; The acceleration means for generating an acceleration signal for focusing on the signal recording surface of another layer, and the information reading means in response to a target address and information of the target layer being given. Calculating means for calculating the movement amount of the information reading means from the current address and layer information being read, and driving means for driving the information reading means to move by the calculated movement amount;
And a control unit for generating an acceleration signal from the acceleration unit, applying the generated signal to the information reading unit, and focusing on the signal recording surface of the target layer.

According to the second aspect of the present invention, optical disks having different substrate thicknesses are interchangeably reproduced.

[0013]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, a single-sided read DVD
The dual-layer disc 1 is driven to rotate by a spindle motor 2, and information recorded on the disc 1 is read by a pickup 3. A signal such as a focus error signal FE is output from the pickup 3, amplified by a head amplifier 4, supplied to an A / D converter 5, and converted from an analog signal to a digital signal. This digital signal is provided to a DSP (Digital Signal Processor) 6.

A ROM 6 and a RAM 8 are connected to the DSP 6. The ROM 7 stores a program for controlling the DSP 6, and the RAM 8 stores information obtained from the disk 1. The DSP 6 executes a program stored in the ROM 7, controls the focus servo of the pickup 3 by an acceleration signal or a deceleration signal, and controls the seek of the pickup 3 based on the information stored in the RAM 8. Perform DSP
6 outputs a digital signal for controlling the focus jump to the D / A converter 9, and the D / A converter 9 converts the digital signal into an analog signal and supplies the analog signal to the driver 10. The driver 10 controls the pickup 3 based on the acceleration signal and the deceleration signal.

Further, the DSP 6 outputs a PWM (Pulse Wide Modulation) signal for seeking the pickup 3 and supplies it to the integrator 11. Integrator 11 is PWM
The signal is integrated and given to the driver 12 as a sled drive signal. The driver 12 drives the feed mechanism 13 by the sled drive signal to cause the pickup 3 to seek.

FIG. 2 is a diagram showing the structure of the pickup shown in FIG. 2, the pickup 3 includes a semiconductor laser 31 which emits a laser beam having a wavelength of, for example, 635 nm. The laser beam from the semiconductor laser 31 is incident on the liquid crystal panel 32, the polarization plane is rotated, and is incident on the half mirror 33. The half mirror 33 reflects the laser beam in half and makes the laser beam incident on the collimator lens 34. The collimator lens 34 converts the laser beam into parallel light, which is reflected by the mirror 35 at 90 °. The reflected laser beam passes through the polarizing plate 36, is condensed by the objective lens 37, and is irradiated on the signal recording surface of the disk.

The laser beam reflected by the signal recording surface is
The light returns through the objective lens 37, the polarizing plate 36, the mirror 35, and the collimator lens 34, is partially transmitted by the half mirror 33, is collected by the photodetector 38, and is detected. Photodetector 38
Is divided into four light receiving surfaces a to d, and a + b + c +
d becomes the amount of light B to be output, and (a + c)-(b + d)
Is output as a focus error signal FE (S-curve signal).

When a voltage is applied to the TN type liquid crystal, that is, when the polarization plane of the laser beam is not rotated by 90 °, the outer peripheral portion of the laser beam is not transmitted by the polarizing plate 36 and is transmitted as it is. In this case, the substrate thickness is 0.6 m
m DVD is played. On the other hand, when no voltage is applied to the TN type liquid crystal, that is, when the polarization plane of the laser beam is rotated by 90 °, the outer periphery of the laser beam is shielded by the polarizing plate 36. In this case, a CD having a substrate thickness of 1.2 mm is reproduced. Since the polarization direction of the laser beam emitted from the semiconductor laser is perpendicular to the plane of the drawing, the polarization plate 36
Means that only a laser beam polarized in a direction perpendicular to the paper surface is transmitted. When the laser beam is not shielded, the numerical aperture of the objective lens 37 is 0.60 (tolerance ± 0.
05), and when the outer peripheral portion of the laser beam is shielded, the effective numerical aperture of the objective lens 37 is 0.35 (allowable error ± 0.05).

FIG. 3 is a view showing a driving mechanism of an objective lens for focusing and tracking. In FIG. 3, the objective lens 37 is held by a lens holder 40, and a focus coil 41 is wound around the lens holder 40.
Tracking coils 42a, 42
b is provided. The lens holder 40 is attached to a fixed base 44 via a leaf spring 43. Further, yokes 46 and 47 and a permanent magnet 48 are attached to the yoke base 45, and the tip of the yoke 47 is inserted into a space between the lens holder 40 and the focus coil 41.

When the focus coil 41 is driven, the lens holder 40 is moved by the action of the magnetic flux of the permanent magnet 48 and the magnetic flux generated by the current flowing through the focus coil 41.
And the laser beam is controlled to focus on the signal recording surface of the disk. When the tracking coils 42a and 42b are driven, the lens holder 4
0 is tracked in the Y direction.

FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention, and FIG. 5 is a diagram for explaining the operation of the focus jump and the seek of the target address in the embodiment of the present invention. .

Next, a specific operation of the embodiment of the present invention will be described with reference to FIGS. DSP6
When a destination address of the disk 1 and target layer information are given from outside, the position and layer information addressed by the pickup 3 are obtained, and a movement amount from the current position to the destination is calculated. For example, as shown in FIG. 5, the pickup 3 focuses on the point a of the translucent recording layer A,
When a command for focusing on the point b of the reflective recording layer B is given by a command from the outside, the movement amount from the point a to the point b is calculated, and the DSP 6 calculates the tracking coil 42a of the pickup 3 shown in FIG. , 42b, the PWM signal is output to the integrator 11, and the integrator 1
1 integrates the PWM signal and outputs a thread drive signal as shown in FIG. The driver 12 drives the feed mechanism 13 according to the thread drive signal. Thereby, the pickup 3 starts moving by the feed mechanism 13.

The DSP outputs D / A simultaneously with the output of the PWM signal.
The focus error signal FE is output to the converter 9. The focus error signal FE is converted into an analog signal by the D / A converter 9 and is provided to the driver 10. The driver 10 starts the focus jump start of the pickup 3 by the focus error signal FE of the analog signal. As a result, the pickup 3 moves from the translucent recording layer A, which is the first layer, to the reflective recording layer B, which is the second layer, and ends the focus jump.

At this time, the DSP 6 determines whether or not the pickup 3 has reached point b of the reflective recording layer B. If not, the DSP 6 continues to output a thread drive signal. Then, when the pickup 3 reaches the vicinity of the target address, the movement by the feed mechanism 13 is terminated, the track jumps to the designated track of the reflective recording layer B, and the tracking is turned on to reach the target address. I do.

As described above, according to this embodiment, the pickup 3 is moved from the first layer to the second layer based on the focus error signal FE while seeking the address of the pickup 3 by the sled drive signal. As a result, the access time can be reduced, and the value of the computer as a memory can be increased.

[0026]

As described above, according to the present invention, in response to the information of the target address and layer being given,
The movement amount is calculated from the current address and the information of the layer, the driving means is driven so as to move the information reading means by the calculated movement amount, and the acceleration signal is generated to match the signal recording surface of the target layer. Since it is made to focus, access time can be shortened.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a pickup illustrated in FIG. 1;

FIG. 3 is a diagram showing a driving mechanism of an objective lens for focusing and tracking.

FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention;

FIG. 5 is a diagram for explaining an operation of seeking a focus jump and a target address in one embodiment of the present invention.

FIG. 6 is a sectional view schematically showing the structure of a single-sided reading dual-layer disc.

FIG. 7 is a timing chart for explaining a pickup control method in a conventional focus jump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double-layer disc 2 Spindle motor 3 Pickup 4 Head amplifier 5 A / D converter 6 DSP 7 ROM 8 RAM 9 D / A converter 10, 12 Driver 11 Integrator 31 Semiconductor laser 32 Liquid crystal panel 33 Half mirror 34 Collimator lens 35 Mirror 36 Polarizing plate 37 Objective lens 38 Photodetector 40 Lens holder 41 Focus coil 42a, 42b Tracking coil 44 Fixing table 45 Yoke base 46, 47 Yoke 48 Permanent magnet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Tada 2-5-5 Keihanhondori, Moriguchi City, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Inventor ▲ Taka ▼ Tree Naoyuki Keihanhondori, Moriguchi City, Osaka 2-5-5 Sanyo Electric Co., Ltd. (72) Inventor Shuichi Ichiura 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. 5D117 AA02 CC06 DD05 EE07 EE13 FF18 FX06 FX07 GG03 GG06

Claims (2)

[Claims] 1. An optical disk apparatus for reproducing an optical disk having information recorded on signal recording surfaces of a plurality of layers, wherein the optical disk is irradiated with a beam, and the reflected light is detected to read the information. Information reading means, driving means for moving the information reading means along a signal recording surface, and when the information reading means is focused on any one of the plurality of layers, An accelerating means for generating an accelerating signal for focusing on a signal recording surface; a target address and a current address at which the information reading means is reading information in response to information of a target layer given; Calculating means for calculating the amount of movement of the information reading means from the information of the layer and the layer; and driving the driving means such that the information reading means moves by the amount of movement calculated by the calculating means. Together with the accelerating means to generate an acceleration signal from the applied to said information reading means, having a control means for focusing on the signal recording surface of the layer of interest, the optical disk apparatus. 2. The optical disk device according to claim 1, wherein said optical disks are optical disks having different substrate thicknesses, and said different optical disks can be compatiblely reproduced.