JP2000200427A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk device capable of preventing the erroneous operation of the focus jump. SOLUTION: An acceleration signal is outputted by a DSP(digital signal processor) 6, and this accelaration signal is converted to an analog signal by a D/A converter 9 and amplified by a driver 10 to drive a focus coil of a pickup 3. At the same time, a timer is started by the DSP 6, and the jump in the opposite direction is started provided that the level of a focus error signal is not detected from a head amplifier 4 within the specified time, thereby the pickup 3 is prevented from running into a 2-layer disk 1.

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 array 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 DVD has a thickness of about 0.6 mm. By laminating the DVDs on both sides, a two-layer disc can be formed, and 9.4 Gbytes of information can be recorded on one double-layer disc.

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 and a method of reproducing one signal from both surfaces of the disk are described.
One signal recording surface may be reproduced. 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, it is not possible to reproduce another signal recording surface while reproducing one signal recording surface. For this reason, a method of reproducing two signal recording surfaces from one surface has become mainstream.

FIG. 8 is a sectional view schematically showing the structure of a single-sided reading dual-layer disc. As shown in FIG. 8, 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 gold or the like and having a reflectivity of about 30%. A, and an ultraviolet curable resin having a thickness of about 40 μm as an intermediate layer C is sandwiched between these two layers.

In this two-layer disc, one of the layers is of a translucent type, so that the laser beam (beam) can be seen from one side.
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 one layer is being reproduced, 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. 9 is a diagram for explaining a conventional pickup jump control method in a focus jump. 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). 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 to the deceleration pulse shown in FIG.

[0009]

However, a pulse may not be obtained from the reflective surface of the disk due to scratches on the surface of the disk, or a pulse from the reflective surface may not be obtained due to surface deviation or impact. Since the focus error signal FE shown in FIG. 9 is obtained by detecting a pulse from the reflection surface of the disk with a photodetector, if P2 is not detected after P1 is detected in FIG. Since a deceleration pulse cannot be given to the actuator, a malfunction occurs in which the focus actuator collides with the disk.

[0010] Therefore, a main object of the present invention is to provide an optical disc apparatus capable of preventing a malfunction of a focus jump.

[0011]

The invention according to claim 1 is
What is claimed is: 1. An optical disk drive for reproducing an optical disk having information recorded on signal recording surfaces of a plurality of layers, comprising: an information reading unit for irradiating the optical disk with a beam and detecting reflected light to read information; Means for generating an acceleration signal for focusing on a signal recording surface of another layer when the apparatus is focused on any one of the signal recording surfaces of the plurality of layers and supplying the acceleration signal to the information reading means; A deceleration signal for stopping the information reading means is generated in response to a predetermined reflected light not being obtained from the information reading means within a predetermined time after supplying the acceleration signal from the means to the information reading means. And a deceleration means for giving to the information reading means.

According to a second aspect of the present invention, there is provided an optical disk apparatus for reproducing an optical disk having information recorded on a plurality of signal recording surfaces of a plurality of layers, wherein the optical disk is irradiated with a beam and the reflected light is detected to detect the information. And an acceleration signal for focusing on a signal recording surface of another layer when the information reading unit is focused on any one of the signal recording surfaces of the plurality of layers. An accelerating means for supplying the information reading means and an accelerating signal supplied from the accelerating means to the information reading means, and the information reading means is stopped in response to the fact that a predetermined level of reflected light is not obtained from the information reading means. And a deceleration unit for generating a deceleration signal for use in the information reading unit.

In the invention according to claim 3, the acceleration means according to claim 1 or 2 stops the information reading means by the deceleration means, then generates an acceleration signal again and gives the acceleration signal to the information reading means.

According to a fourth aspect of the present invention, the information reading means outputs an S-curve signal as a signal indicating focus, and the deceleration means cannot obtain the S-curve signal within a predetermined time. A deceleration signal is generated in response to this.

According to the fifth aspect of the present invention, when the predetermined time of the first aspect is focused on one of the plurality of layers, the acceleration signal is used to focus on the signal recording surface of another layer. It is selected to be several times the required time.

In the invention according to claim 6, the predetermined level of reflected light is selected to be a fraction of the level of reflected light obtained from the information reading means.

[0017]

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, and the RAM 8 stores information obtained from the disk 1. The DSP 6 executes a program stored in the ROM 7, and performs control for specifying the position of the pickup 3 by an acceleration signal or a deceleration signal based on information stored in the RAM 8. The DSP 6 outputs a digital signal for the control to the D / A converter 9,
The / 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.

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 by half and makes the laser beam incident on a 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 light quantity P to be output, and (a + c)-(b + d)
Is output as a focus error signal FE (S-curve signal).

The liquid crystal panel 32 is configured by sandwiching a TN type liquid crystal between two sheets of glass with a transparent electrode. When a voltage is applied to the transparent electrode, a voltage is applied to the TN type liquid crystal, and the laser beam is polarized by its polarization plane. Pass through the TN type liquid crystal without being rotated. When no voltage is applied to the transparent electrode, the laser beam rotates its polarization by 90 ° and passes through the TN liquid crystal.

FIG. 3 is a diagram showing a driving mechanism of an objective lens for focusing and tracking. 3, the objective lens 37 shown in FIG. 3 is held by a lens holder 40, a focus coil 41 is wound around the lens holder 40, and both end surfaces of the focus coil 41 in the Y direction. Has a tracking coil 4
2a and 42b are provided. The lens holder 40 is attached to a fixed base 44 via a leaf spring 43. further,
The yoke base 45 includes yokes 46 and 47 and a permanent magnet 48.
Are attached, and the tip of the yoke 47 is inserted into the 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 47 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 embodiment of the present invention.

In this embodiment, after the acceleration signal is given to the pickup 3, the focus jump is controlled and the counting of the timer is started. If a predetermined time has elapsed, the focus jump is performed in the opposite direction. is there. More specifically, as shown in FIG. 5, the disc has an N-1 layer, an N layer, and an N + 1 layer, and after the pickup 3 makes a focus jump from the N-1 layer to the N layer, Focus jump to layer.

The DSP 6 outputs an acceleration signal at timings a and b of the focus error signal FE shown in FIG. 5 in order to cause a focus jump from the N layer to the N + 1 layer. This acceleration signal is converted into an analog signal by the D / A converter 9 and amplified by the driver 10, and the focus coil 41 shown in FIG. 3 is driven. At this time, the DSP 6 starts after resetting the built-in timer. This timer may be configured by hardware such as a counter, or may be one that counts time by software.

The DSP 6 determines whether the count value of the timer has exceeded a predetermined value Tout. If it does not exceed Tout, the level of the focus error signal FE is detected. The level of the focus error signal FE is
If the zero-cross point indicated by point c is reached, the focus jump ends. However, if the timer exceeds Tout, it is determined that there is an abnormality, and a backward jump is started to prevent the pickup 3 from colliding with the disk surface. Here, if the time required for a focus jump from the N layer to the N + 1 layer is, for example, 2 msec, T
Out is selected to be, for example, several times of 5 msec.

FIG. 6 is a block diagram showing a second embodiment of the present invention. In this embodiment, after the acceleration signal is output for the focus jump, when the light amount level exceeds a predetermined value, the focus jump in the reverse direction is performed. For this reason, as shown in FIG. 6, not only the focus error signal FE but also the light amount signal p is output from the head amplifier 4, and is converted into a digital signal by the A / D converter 10 and supplied to the DSP 6. Other configurations are the same as those in FIG.

FIG. 7 is a flowchart for explaining the operation of the second embodiment of the present invention. Next, the operation of this embodiment will be described with reference to FIG. 5 of the first embodiment. First, as in the first embodiment, D
The SP 6 supplies an acceleration signal to the D / A converter 9 to control a focus jump. The acceleration signal is supplied to the D / A converter 9
Is converted into an analog signal, amplified by the driver 10, and given to the focus coil 41 of the pickup 3. The photodetector 38 detects reflected light from the disk,
The head amplifier 4 receives the light amount signal p and the focus error signal F
And E. Each signal is converted into a digital signal by A / D converters 10 and 5 and provided to DSP 6. The DSP 6 measures the light amount signal p and compares it with a predetermined light amount value Pout shown in FIG. If the light amount signal p is smaller than a predetermined light amount value Pout, the level of the focus error signal of the (N + 1) th layer is detected. If the level is the zero-cross point of the point c shown in FIG. 5, the focus lamp ends.

However, the light quantity signal p is equal to the light quantity value Pou.
If it exceeds t, it is determined that there is an abnormality, and a backward jump is started to prevent the pickup 3 from colliding with the disk.

[0031]

As described above, according to the present invention, when focusing on a signal recording surface of any layer of an optical disc, acceleration is performed to focus on a signal recording surface of another layer. When a signal is given, when a reflected light is not obtained within a predetermined time or when a reflected light of a predetermined level is not obtained, a deceleration signal is given to the information reading means to decelerate, thereby colliding with the optical disk. Can be prevented.

[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 the operation of the embodiment of the present invention.

FIG. 6 is a block diagram showing a second embodiment of the present invention.

FIG. 7 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 8 is a sectional view schematically showing the structure of a single-sided reading dual-layer disc.

FIG. 9 is a timing chart for explaining a pickup control method in a conventional focus jump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Double-layer disk 2 Spindle motor 3 Pickup 4 Head amplifier 5, 10 A / D converter 6 DSP 7 ROM 8 RAM 9 D / A converter 10 Driver 31 Semiconductor laser 32 Liquid crystal panel 33 Half mirror 34 Collimator lens 35 Mirror 36 Polarization 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

Continued on the front page (72) Inventor Koichi Tada 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Watanabe 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Shuichi Ichiura 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term within Sanyo Electric Co., Ltd. 5D117 AA02 BB01 CC01 DD05 DD14 FF05 FX08

Claims (6)

[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 information is read by irradiating the optical disk with a beam and detecting reflected light thereof. Reading means, when the information reading means is focused on a signal recording surface of any of the plurality of layers, generating an acceleration signal to focus on a signal recording surface of another layer, and reading out the information. Accelerating means for supplying the information to the information reading means, and when the predetermined reflected light is not obtained from the information reading means within a predetermined time after supplying an acceleration signal from the accelerating means to the information reading means, An optical disc device comprising: a deceleration means for generating a deceleration signal for stopping the reading means and providing the deceleration signal to the information reading means. 2. An optical disk apparatus for reproducing an optical disk having information recorded on signal recording surfaces of a plurality of layers, wherein the information is read by irradiating the optical disk with a beam and detecting reflected light thereof. Reading means, when the information reading means is focused on a signal recording surface of any of the plurality of layers, generating an acceleration signal to focus on a signal recording surface of another layer, and reading out the information. An accelerating means for supplying the accelerating signal to the information reading means, and supplying the acceleration signal from the accelerating means to the information reading means. An optical disc device, comprising: a deceleration unit for generating a deceleration signal for stopping the rotation and giving the deceleration signal to the information reading unit. 3. The optical disk according to claim 1, wherein said acceleration means stops said information reading means by said deceleration means, and then generates an acceleration signal again and gives it to said information reading means. apparatus. 4. The information reading means outputs an S-curve signal as a signal indicating focus, and the deceleration means responds to a failure in obtaining the S-curve signal within the predetermined time. 2. The optical disk device according to claim 1, wherein the deceleration signal is generated. 5. The predetermined time is several times as long as the time required for focusing on a signal recording surface of another layer by the acceleration signal when focusing on one of the plurality of layers. The optical disk device according to claim 1, wherein the optical disk device is selected. 6. The optical disk apparatus according to claim 2, wherein said predetermined level of reflected light is selected to be a fraction of the level of reflected light obtained from said information reading means.