JP2003233912A - Optical disk unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately discriminate various disks by preliminarily obtaining the current actuator sensitivity and giving the exact time reference to the disk discrimination. <P>SOLUTION: An optical disk unit is furnished with a turntable 7 for placing the disk 2, a pickup 1 for irradiating the disk with a laser beam, an objective lens 10 arranged on the pickup to focus the laser beam to the disk, an actuator 5 for making the objective lens move to the direction approaching or separating with respect to the disk, a control circuit 4 for bringing the objective lens to the focusing position for holding it, and a driving means 6 for moving the objective lens to the radial direction of the disk, and in this optical disk unit, a reflection surface is formed on the surface at the pickup side of the turntable 7 and the reflection surface of the turntable 7 is irradiated with the laser beam emitted from the pickup 1, then the return laser beam from the reflection surface is received to obtain the sensitivity of the actuator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device for reading information from an optical disc by optical means,
Particularly, it relates to a technique for discriminating various optical disks.

[0002]

2. Description of the Related Art A conventional optical disk device has two lasers, a laser for a CD disk (hereinafter referred to as a CD laser) and a laser for a DVD disk (hereinafter referred to as a DVD laser), and an optical pickup. The lens of is also a lens for CD disc (hereinafter called CD lens)
And a lens for DVD (hereinafter, referred to as a DVD lens), and a disc and a laser were combined to reproduce.

On the other hand, as the optical disc, a CD disc, a single-layer disc of DVD, a double-layer disc of DVD, a CD-R (Write Once) disc, a CD.
-RW (Rewritable) disks and the like are known.

Conventionally, in order to distinguish these optical disks,
When the optical disk is mounted on the optical disk device, the optical disk is reproduced by the combination of the CD laser and the CD lens to detect the amplitude of the focus error signal. Next, DVD laser and D
The optical disc is reproduced by the set of VD lenses to detect the focus error signal. The focus error signals of both sets are compared, and the set of the laser and lens with the larger amplitude is the laser and lens suitable for the mounted optical disk.
This laser and lens were used. Further, it is possible to discriminate whether the optical disc mounted from the selected laser and lens is a CD disc or a DVD disc.

When the selected laser and lens are a CD laser and a CD lens, the amplitude of the focus error signal obtained from the CD disc is determined. Since the CD disc has a larger amplitude of the focus error signal than the CD-RW disc, it is determined whether the amplitude of the focus error signal is larger or smaller than a predetermined value, and the amplitude of the focus error signal is predetermined. If the amplitude of the focus error signal is smaller than a predetermined value, it is determined to be a CD-RW disc. Since CD-R discs are handled in the same manner as CD discs, it is not necessary to distinguish these discs.

When the selected laser and lens are a DVD laser and a DVD lens, the amplitude of the focus error signal obtained from the DVD disc is measured. Since the amplitude of the focus error signal of the DVD single layer disc is larger than that of the DVD double layer disc, it is determined whether the amplitude of the focus error signal is larger or smaller than a predetermined value, and the amplitude of the focus error signal is predetermined. If the amplitude of the focus error signal is smaller than a predetermined value, D is determined as a DVD single-layer disc.
It is determined that the disc is a VD dual layer disc.

As described above, the CD laser, the CD lens, and the D
In the conventional optical disc device that selectively uses the VD laser and the DVD lens, as described above, the CD disc (or CD-R disc), the DVD single layer disc, the DVD double layer disc, and the CD- RW (Rewri
table) Disc was being discriminated.

In recent years, a bifocal lens applicable to both CD disks and DVD disks has come to be used as a pickup lens. In this case, various CD disks and various DVD disks cannot be discriminated as in the conventional example.

As a countermeasure in this case, a disc discriminating method which can easily discriminate an optical disc in an optical disc device having a bifocal lens applicable to a disc relating to CD and a disc relating to DVD is proposed as follows. Has been done.

When any one of the optical disks is loaded in the optical disk device, the focus error signal from the recording surface of the loaded optical disk is detected by using either the CD laser or the DVD laser. The focus error signal from the recording surface of the optical disc is DV even when the CD laser is used.
Even when the D laser is used, a signal having a magnitude corresponding to the reflectance of the optical disc can be obtained. Based on the detected amplitude of the focus error signal, it is determined whether the mounted optical disk has a high reflectance or a low reflectance.

In FIG. 3, the recording surface of the optical disc 2 is irradiated with laser light from the optical pickup 1, the reflected laser light is detected by the optical pickup 1, and a focus error signal is generated by the signal processing circuit 3, and the focus error signal is generated. The error signal is input to the microcomputer 4. The microcomputer 4 determines the magnitude of the reflectance of the optical disc 2 mounted from the amplitude of the input focus error signal.

Next, a method and apparatus for discriminating whether the optical disc in the optical disc group having a high reflectance or the optical disc group having a low reflectance is a CD-related optical disc or a DVD-related optical disc will be described. Even if the moving speed of the pickup when the optical pickup 1 is brought close to the optical disc 2 is CD-related optical disc,
The same applies to VD-related optical discs, or the same moving speed of the pickup when the optical pickup 1 is moved away from the optical discs, such as CD-related optical discs and DVD-related optical discs, when the optical pickup 1 is brought close to the optical disc, or By measuring the time between the reflection signal from the surface of the optical disc and the reflection signal from the recording surface of the optical disc when the optical disc is moved away from the optical disc, it is possible to determine whether the optical disc is a CD-related optical disc or a DVD-related optical disc.

That is, the microcomputer 4 measures the time between the reflection signal from the surface of the optical disc and the reflection signal from the recording surface of the optical disc, and determines whether the value is larger or smaller than a predetermined value. , A CD-related optical disc or a DVD-related optical disc can be discriminated.

As described above, in the conventional example, an optical disc having a high reflectance, that is, a CD disc and a DVD single-layer disc (or a DVD double-layer disc), or an optical disc having a low reflectance, that is, a CD-RW disc and a D-disk.
Whether the disc is a VD-RAM disc is discriminated from the amplitude of the focus error signal, and then the time between the reflection signal from the surface of the optical disc and the reflection signal from the recording surface is measured to determine whether the disc is a CD-related disc or a DVD-related disc. Since the disc is discriminated, it is possible to discriminate which optical disc is the optical disc mounted in the optical disc device.

As described above, in the conventional example, the optical disk device is a CD disk, a DVD single layer disk, a DV.
D2 layer disc, CD-RW disc, DVD-RAM
It can be discriminated whether the disc or the CD-R disc.

When the microcomputer 4 discriminates the optical disk mounted on the optical disk, a command from the microcomputer 4 causes
A laser suitable for the optical disc is selected, and the servo condition of the tracking servo and the focus servo can be determined according to the mounted optical disc, and the condition of the rotation control of the spindle motor can be determined if necessary. .

[0017]

However, even in the disc discrimination as described above, there is a problem in discriminating between the DVD dual-layer disc and the SACD dual-layer disc. In other words, for discs having the same FE (Focus Error) level but different gap distances between the two layers according to the standard, the actual lens can be judged only by the difference in the time axis of the FE signal that appears as the lens moves. Due to variations in the sensitivities of actuators and actuator driver circuits and changes in the sensitivities due to changes in the environment, there arises a problem that a preset judgment criterion for the time axis is exceeded and misjudgment is caused.

Therefore, the object of the present invention was made in view of such a situation, and the sensitivity of the current actuator is obtained and the time base reference is corrected to provide an accurate time reference for disc discrimination in the related art. To solve the conventional problems.

[0019]

To solve the above problems, the present invention mainly adopts the following configurations. A turntable on which a disc is placed, a pickup that irradiates the disc with laser light, an objective lens that is provided on the pickup and focuses the laser light on the disc, and the objective lens moves toward or away from the disc. In the optical disc device, an actuator for driving the objective lens, a control circuit for bringing the objective lens to a focusing position and holding the objective lens, and a drive unit for moving the objective lens in the disc radial direction are provided. An optical disk device in which a reflective surface is formed on the surface, the laser light emitted from the pickup is applied to the reflective surface of the turntable, and the return laser light from the reflective surface is received to obtain the sensitivity of the actuator.

Further, a turntable on which the disc is placed, a pickup for irradiating the disc with laser light, an objective lens provided on the pickup for focusing the laser light on the disc, and the objective lens approaching the disc. Alternatively, in an optical disc device including an actuator that moves in a separating direction, a control circuit that brings the objective lens to a focusing position and holds it, and a drive unit that moves the objective lens in a disc radial direction, The pulse interval of two light receiving pulses corresponding to the return light from the surface of the disk and the recording surface is obtained, the sensitivity of the actuator is measured in advance, and the disk type is determined based on the measured actuator sensitivity and the pulse interval. Optical disc device that determines

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An optical disk device according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a configuration of an optical disk device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a lamp voltage and a focusing pulse of a focusing operation according to the embodiment of the present invention. here,
1 is a pickup, 2 is a disc, 3 is a signal processing circuit,
Reference numeral 4 is a microcomputer (lamp circuit, servo circuit), 5 is an actuator, 6 is a drive circuit, 7 is a turntable, 8 is a spindle motor, 9 is a signal generation circuit, and 10 is an objective lens. The lower surface of the turntable 7 is made of a material that reflects laser light, such as aluminum vapor deposition.

First, in the initial operation of reading a disc, the pickup 1 is preliminarily set by the drive circuit 6 at the inner peripheral position A, that is, on the reflection surface of the turntable 7 further inside the disc recording area (hereinafter referred to as position A). A lamp voltage having a constant lamp speed S (V / sec) is applied to the actuator to raise the focus lens, and a focusing pulse is obtained by the signal processing circuit 3 as shown in (1) of FIG. Then, the waveform is taken into the microcomputer and the timing ta from the start of the ramp waveform when the pulse is generated is obtained. That is, the time elapses from when the actuator voltage starts to be applied to when the voltage reaches Va and the focus error becomes zero (focus state).
a. At that time, the actuator voltage is increased at a constant slope S.

Next, the driving circuit 6 picks up the pickup 1
At the inner circumferential position B, that is, at the inner circumferential side of the disk recording area (hereinafter referred to as position B), a ramp voltage having a constant ramp speed S (V / sec) is applied to the actuator 5 (actuator voltage gradient). Is constant and is the same as (1) in FIG. 2), and as shown in (2) in FIG. 2, the timing tb from the start of the ramp waveform when the pulse is generated is obtained.

The dimension Lo (mm) in the thickness direction of the turntable 7 is managed as a design condition in advance, and the distance between the lower portion of the turntable where the focusing pulse is detected and the disc surface is set to be always constant. It has been done.

These conditions are calculated by the microcomputer 4, and the actuator sensitivity coefficient K (mm / V) is obtained as shown in Equation 1.

K = Lo / {S × (Tb−Ta)} (Equation 1) The operation for obtaining K may be performed for each disk chucking or may be performed for the first time when power is turned on. In short, assuming that the actuator sensitivity is likely to vary, this may be set in the microcomputer and K may be calculated each time.

Using the K obtained here, the distance L from the disk surface to the recording surface is calculated as in the prior art, and each disk is discriminated. That is, the distance L is obtained as shown in Expression 2.

L = K × S × (Tc−Tb) (Equation 2) Tc in Equation 2 is the timing (time interval) from the start of the ramp waveform when a pulse is generated to the time of focusing on the disk recording surface. is there.

As described above, according to the present invention, the sensitivity coefficient K is obtained in advance as shown in the equation 1 even with respect to the inherent sensitivity variation of the actuator mechanism and the sensitivity change due to the environment, and this K is calculated. The distance L between the disk surface and the disk recording surface is obtained by measuring the time interval of the reflection signal from the disk surface and the disk recording surface using D
Disc identification such as VD and SACD having different distances between two layers can be accurately performed.

[0030]

According to the present invention, the sensitivity of the actuator is previously set in the optical disc device capable of automatically determining the type of the optical disc by measuring the time between the reflection signals from the surface of the optical disc and the recording surface. By detecting in advance, it is possible to follow the originally existing sensitivity variations and sensitivity changes due to environmental changes, so no matter how the sensitivity of the drive device varies, discs such as DVD and SACD that have different distances between two layers. It is possible to make an accurate determination in the determination, and it is possible to accurately determine the disc.

Further, in the present invention, the optical disc can be discriminated from the focus signal detected by the optical pickup without reading all the recorded data except for moving the optical pickup, which is inexpensive. In addition, it is possible to perform optical disc discrimination with high speed and good detection sensitivity.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a ramp voltage and a focusing pulse in a focusing operation according to the embodiment of the present invention.

FIG. 3 is a functional block diagram of an optical disc device in the related art.

[Explanation of symbols]

1 pickup 2 discs 3 Signal processing circuit 4 Microcomputer (lamp circuit, servo circuit) 5 actuators 6 drive circuit 7 turntable 8 spindle motor 9 Signal generation circuit 10 Objective lens

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5D066 HA01                 5D090 AA01 BB02 BB12 CC09 CC18                       DD02 FF05 HH01 JJ11                 5D117 AA02 CC07 DD06 FF03 FF04                       FF28                 5D118 AA14 AA26 BA01 CC12 CD02

Claims (3)

[Claims] 1. A turntable on which a disc is placed, a pickup for irradiating the disc with laser light, an objective lens provided on the pickup for focusing the laser light on the disc, and the objective lens approaching the disc. Alternatively, in an optical disc device including an actuator that moves in a separating direction, a control circuit that brings the objective lens to a focusing position and holds the objective lens, and a drive unit that moves the objective lens in a disc radial direction, A reflective surface is formed on the pickup-side surface of the turntable, the laser light emitted from the pickup is applied to the reflective surface of the turntable, and the return laser light from the reflective surface is received to increase the sensitivity of the actuator. An optical disk device characterized by demands. 2. A turntable on which a disc is placed, a pickup for irradiating the disc with laser light, an objective lens provided on the pickup for focusing the laser light on the disc, and the objective lens approaching the disc. Alternatively, in an optical disc device including an actuator that moves in a separating direction, a control circuit that brings the objective lens to a focus position and holds it, and a drive unit that moves the objective lens in a disc radial direction, The pulse interval of two light-receiving pulses corresponding to the returning light from the surface of the disk and the recording surface is obtained, the sensitivity of the actuator is measured in advance, and the disk type is determined based on the measured actuator sensitivity and the pulse interval. An optical disk device characterized by determining. 3. The optical disk device according to claim 2, wherein the sensitivity of the actuator is measured by receiving laser light emitted from the pickup and returned from a reflection surface on the pickup side of the turntable. Characteristic optical disk device.