JP2002269788A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the exact amount of tilt at the position for recording or reproducing the information is undetectable in a conventional optical disk device since the position of a light beam on the optical disk for recording or reproducing the information and the position of the light beam on the optical disk for detecting the amount of tilt are different. SOLUTION: This optical disk device is provided with a 2nd light source for irradiating the optical disk by the light beam to detect the tilt of the optical disk and a light detecting means for detecting the light reflected from the optical disk, then its constitution is featured by that the beam from the 2nd light source is reflected and the vicinity of the position on the optical disk irradiated by the light beam from the 1st light source is irradiated by the above reflected beam, and the light beam from the 2nd light source is arranged so as to be detected by the light detecting means through the same number of reflections made by the above optical means and the optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus provided with a tilt sensor for detecting an inclination (tilt) of an optical disk on which an information signal is written / read by a light beam and correcting the inclination. .

[0002]

2. Description of the Related Art In recent years, for example, in the field of recording or reproducing using an optical disk as a recording medium, a demand for a small-sized and large-capacity optical disk recording / reproducing apparatus for handling high-definition still images and moving images has been increased. ing. As a technical method for satisfying this requirement, for example, it is conceivable to shorten the wavelength of the laser light source emitted from the optical pickup device and to reduce the beam spot diameter by the high NA (NA: numerical aperture) of the objective lens. However, if the recording density is increased by shortening the wavelength and using a high NA objective lens to reduce the beam spot diameter and narrowing the track pitch and pit pitch of the optical disc, if the optical disc tilts with respect to the optical pickup, Due to the coma generated at this time, the diameter of the beam condensed by the objective lens becomes larger than before, and it becomes difficult to accurately record or reproduce a signal. The coma aberration ΔW generated by the tilt of the optical disk is represented by a numerical aperture NA,
The relationship between the wavelength λ and the disk thickness t can be expressed by the following equation. ΔW∝t · (NA) 3 / λ In other words, it can be seen that the effect of coma aberration increases when the NA is large and the wavelength is short. Therefore, shorter wavelength and higher
When an NA objective lens is used, if the disk is tilted, the light beam condensed by the objective lens becomes distorted and becomes large, and the mutual interference between the original signal and the signal from the adjacent track, that is, crosstalk and the sign before and after Interference increases compared to the conventional device, and it becomes difficult to accurately record / reproduce information signals. Therefore, a means for correcting the disk inclination is required. That is, accurate tilt detection and its correction or reduction technology are essential.

Here, as a means for correcting the disc tilt, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 3-37831, a method for correcting a coma aberration generated by tilting an objective lens in accordance with the tilt of the disc is disclosed. is there. Further, as a conventional example of detecting the relative tilt amount of the objective lens and the optical disk, Japanese Patent Application Laid-Open No. HEI 3-37831 also discloses that the objective lens and the optical disk are detected by detecting a reflected light beam with a disk and a reflector provided in an optical pickup movable portion. In this example, a tilt sensor is mounted on a movable portion of an actuator in order to detect a relative tilt amount in the radial direction of the optical disk and two axes of the optical disk in the tangential direction and the radial direction.

Further, Japanese Patent Application Laid-Open No. 2513589 discloses a method of detecting the amount of tilt of an optical disk in a radial direction.
A method almost similar to that described above is shown, and an example is shown in which the reflecting portion of the actuator is devised and reflected twice to detect two axes of the optical disk in the tangential direction and the radial direction.

However, according to the technique described in the above publication, the position of the light beam for recording or reproducing information on the optical disk is different from the position of the light beam for detecting the tilt amount on the optical disk. However, there is a problem that the amount of tilt at the position where recording or reproducing is not accurately detected.

[0006] As shown in FIG. 8 of Japanese Patent Publication No. 2513589, the light beam from the objective lens 1 is reflected by the optical disk 4 and detected, while the light beam for tilt amount detection is detected. The beam is reflected by the light reflector 8 and
In FIG. 10, the light beam is reflected by the optical disk 4 and the light beam is reflected by the reflection surfaces 12 and 13 to be detected.

For this reason, in both cases of FIGS. 8 and 10, the light beam from the objective lens 1 (light beam for reproducing information) and the light beam for tilt amount detection are different from each other.
Since the number of times of reflection is different, there is a problem that components other than the amount of tilt are included in the reflection, and it is impossible to accurately detect the amount of tilt.

[0008]

As described above, in the conventional optical disk apparatus, the position of the light beam for recording or reproducing information on the optical disk and the position of the light beam for detecting the amount of tilt on the optical disk. Is different from
There is a problem that the amount of tilt at the position where information is recorded or reproduced cannot be accurately detected.

In addition, since the number of reflections before the light beam for recording or reproducing information and the light beam for detecting the tilt amount are different, the tilt amount cannot be detected accurately. was there.

An object of the present invention is to solve the above-mentioned problems and to provide an optical disk apparatus capable of accurately detecting a tilt amount.

[0011]

In order to achieve the above object, in an optical disk apparatus according to the present invention, information is reproduced by condensing and irradiating a light beam from a first light source with an objective lens. A second light source for irradiating the optical disk with a light beam in order to detect a tilt of the optical disk; an optical unit for irradiating the optical disk with a light beam from the second light source; Light detecting means for detecting reflected light of the irradiated light beam from the optical disk, wherein the optical means reflects a beam from the second light source, and reflects the beam from the first light source of the optical disk. A light beam from the second light source is irradiated near the position where the light beam from the light source is irradiated, and the light beam from the second light source passes through the same number of times of reflection by the optical means and the optical disk. In characterized by configured to be detected.

The number of times of reflection is a plurality of times.

Further, in order to detect a tilt of an optical disk on which information is reproduced by condensing and irradiating a light beam from the first light source with an objective lens of an objective lens holding means for holding an objective lens, A second light source for irradiating the optical disk with a light beam, and a light beam from the second light source that reflects the light beam and irradiates the optical beam with the light beam from the first light source on the optical disk. A light beam reflecting means provided on the objective lens holding means for irradiating the vicinity of the present position, and a light detecting means for detecting reflected light from the optical disk of a light beam irradiated by the optical means; It is characterized by having.

In addition, the incident angle of the light beam from the second light source to the light beam reflecting means and the incident angle of the light beam from the second light source to the optical disk by the light beam reflecting means are equal. And

The angle of incidence from the second light source to the light beam reflecting means and the angle of incidence of the light beam from the second light source by the light beam reflecting means on the optical disk are:
It is characterized by 60 degrees.

The light beam from the second light source is
The light beam is reflected by the light detecting means after the same number of times of reflection by the light beam reflecting means and the optical disk.

Further, the number of times of reflection is the same as that of the light beam reflecting means and the optical disk, and the number of times of reflection is a plurality of times.

Further, the objective lens holding means has a hole for irradiating the light detecting means with a light beam from the second light source reflected by the optical disk.

Further, the light beam reflecting means includes the second light beam reflecting means.
The light beam from the light source is totally reflected.

The light beam reflecting means is provided integrally with the objective lens holding means.

Further, the invention is characterized in that the second light source and the light detecting means are integrated in one element.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical disk device according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of an optical disk apparatus according to a first embodiment of the present invention. The optical disk 1 is a recording or reproducing disk such as a read-only disk, a phase-change disk, or a magneto-optical disk. The optical disk 1 is held by a chucking mechanism such as a magnetic chuck of a spindle motor 2 fixed to a base (not shown). Alternatively, at the time of reproduction, it is rotationally driven by the spindle motor 2.
The optical head 50 includes a light source 3 for generating a light beam for irradiating the optical disc 1, a photodetector 4, and the like. The light source 3 for reproducing or recording information on the optical disk 1 is, for example, a blue-violet laser having a wavelength of 405 nm. A light beam emitted from the light source 3 is collimated by a collimator lens 5 and passes through a beam splitter 6 Then, the light is turned 90 degrees by the rising mirror 7 and is incident on the objective lens 8. The objective lens 8 allows the optical disk 1
A minute light spot is formed on the upper recording surface. The reflected light from the optical disk 1 passes through the objective lens 8 again, passes through the rising mirror 7, and is guided to the detection system by the beam splitter 6. Then, the light is polarized in the direction of the mirror 9 by the beam splitter 6, collected by the detection lens 10, and enters the photodetector 4.
The photodetector 4 is a multi-segment detector (for example, a four-segment detector) in which a detection area is divided into a plurality of sections, and an output signal of each detection area is calculated by an arithmetic circuit 11 and recorded on the optical disc 1. A reproduction information signal, a focus error signal, and a tracking error signal corresponding to the information are obtained. The focus error signal and the tracking error signal are phase-compensated by the phase compensating circuit 12 and sent to the actuator driving circuit 13, where the actuator is fixed to the fixed portion 501 of the optical head 50 so as to be movable in the tracking direction and the focusing direction. Movable part 14
The objective lens 8 is controlled so as to compensate for the deviation of the optical disc 1 in the focus direction and the deviation in the tracking direction.

Next, a configuration for detecting a relative tilt amount between the optical disc 1 and the actuator movable section 14 holding the objective lens 8 and the like will be described.

The present embodiment is characterized in that the actuator movable section 14 is provided with the reflection mirror 15. As the tilt detection light source 16 provided in the optical head 50, for example, a wavelength of 650 nm
Red LED (Light-Emitting Diode) or red LD (Laser Di
ode), the light beam emitted from the tilt detection light source 16 is incident on the convex lens 17, collimates the light beam, and is collimated into an optical path 90 provided in the actuator movable section 14.
0 and the light is reflected by a reflection mirror 15 provided on this optical path. Thereafter, a light spot is formed near the focal position of the objective lens 8 on the optical disc 1 via the optical path 900.

Since a red LED having a longer wavelength than the light source 3 is used as the tilt detection light source 16, the tilt detection light source 1
The light spot by 6 is larger than the light spot by light source 3, and the two light spots are formed at substantially the same position on the optical disk.

However, since the wavelengths differ greatly,
The tilt amount can be detected at the position of the light spot of the light source 3 without the adverse effects of the light beams from each other.

The light spot of the light source 16 for tilt detection is not limited to the same position as the light spot of the light source 3.
May be near the extent to which some of the light spots overlap.

The light beam reflected by the reflection mirror 15 and the optical disk 1 passes through an optical path (for example, a through hole 1000) secured in the actuator movable section 14 and is reflected by a mirror 18 fixed to an optical head 50. The light is condensed on the photodetector 20 by the convex lens 19. In this manner, the light beams reflected once each by the actuator movable section 14 and the optical disc 1 are condensed on the photodetector 20 by the convex lens 19. The light beam focused on the photodetector 20 is transmitted to the optical disk 1 and the actuator movable unit 1
4 moves on the photodetector 20 in proportion to the relative inclination.

When the tilt control is performed based on the detected tilt amount, the detected tilt amount, that is, the output of the photodetector 20 is calculated by the arithmetic circuit 21, and the phase is compensated by the phase compensating circuit 22. To enter. The actuator drive circuit 23 drives the actuator movable section 14 only in the radial direction of the optical disc 1 or in the radial and tangential directions, and tilts the objective lens 8 according to the amount of tilt of the optical disc 1 in the radial and tangential directions. , Perform tilt control.

Here, FIG. 2 shows only the configuration necessary to explain the present principle from FIG. Figure 2 shows the optical disk
The case where 1 is inclined in the radial direction is also shown at the same time. In FIG. 2, the mirror 18 is omitted for the sake of simplicity. However, the mirror 18 reflects the reflected light from the optical disc 1 and guides the reflected light to the convex lens 19, and is not necessary for explaining the principle. Therefore, it is not shown.

As shown in FIG. 2, when the optical disc 1 tilts in the radial direction by θd, the reflected beam tilts by 2θd which is twice as large as θd. Therefore, the beam movement amount of the light beam on the photodetector 20 due to this inclination can be represented by the focal length f of the convex lens 19 and the inclination amount θd of the optical disc 1, and is f * tan (2θd).

Next, a method of detecting the movement amount will be described with reference to FIG.
This will be described with reference to FIG. FIG. 3 shows an example in which a two-divided photodetector is used as the photodetector 20. When the optical disc 1 is not tilted, the beam becomes a solid line, and when the optical disc is tilted, it becomes a dotted line. By calculating the output difference between the two divisions, the movement amount of the light beam can be detected.
That is, the tilt amount of the optical disc 1 can be detected. At this time, the linear region detection range that changes according to the tilt amount is where the light beam crosses the division line 201. Usually, the light beam on the photodetector 20 is several tens of μm, and the detection range is determined by the size of the light beam. In order to widen the detection range, it is desirable to use the semiconductor position detection element 22 as the photodetector 20.

FIG. 4 shows a semiconductor position detecting element 210 as an example of the photodetector. The semiconductor position detecting element 210 can detect the position of the center of gravity of the light intensity distribution on the detector surface. In FIG. 4, the semiconductor position detecting element 210 detects the difference based on the current difference between the upper and lower electrodes 211 and 212. For this reason, there is no dividing line 201 existing in the two-part photodetector,
If it is within the detection plane, the moving amount of the light beam can be detected. Thereby, a wide detection range can be obtained.

In the case where the objective lens 8 is tilted by the actuator movable section 14 as described above, if tilt control is applied, the actuator movable section 14 shown in FIG.
Tilt, which causes the mirror 15 to also tilt.

FIG. 5 is a schematic diagram showing a state in which the mirror 15 is tilted. Note that FIG. 5 shows only necessary minimum elements for easy understanding of the principle.

In FIG. 5, when the optical disk 1 is tilted by θd (dotted line state), when the reflecting mirror 15 is not tilted, the light beam from the light source 16 reflected by the reflecting mirror 15 is not tilted but reflected by the optical disk 1. The tilted light beam tilts by 2θd. Therefore, the actuator movable part 14 is
Is tilted by θd and the reflecting mirror 15 is also tilted by θd.
The 15 reflected light beams are inclined by 2θd compared to the normal state.
The light beam inclined by 2θd is incident on the optical disk 1 inclined by θd, and θd is incident upon the optical disk 1 and θd is reflected by the optical disk 1 for a total of 2θ.
The amount corresponding to the tilt amount of the tilted light beam of d is reduced, and the tilt of the reflected light beam of the optical disc 1 becomes zero,
The only effect is that the incident position of the light beam with respect to the convex lens 19 is shifted. Since the photodetector 20 is located at the condensing position of the convex lens 19, even if the incident position of the light beam shifts, the light beam is always condensed at the same position unless tilted.

Therefore, only the optical disk 1 is tilted, and the angle is the same as when the actuator movable part 14 is not tilted.

For this reason, if control is performed so that the light beam is always located at the same position on the photodetector 20, it is possible to make the inclination of the optical disk 1 and that of the actuator movable section 14 the same.

Next, the case of detecting the tilt amount in the tangential direction and the radial direction will be described. In order to detect the relative tilt amount in the tangential direction and the radial direction, the mirror 15 of the movable portion of the actuator shown in FIG.
The incident angle of the light beam entering the optical disc 1 is equal to the incident angle of the light beam entering the optical disc 1.

The structure will be described with reference to FIG. FIG. 6 shows only a configuration necessary for the description.

The tilt angle in the tangential direction and the radial direction is detected by making the incident angle θ1 to the reflecting mirror 15 provided in the actuator movable section 14 in FIG. 6 equal to the incident angle θ2 to the disk 1. be able to. In order to explain this, how the reflected light beam of the light beam incident on the surface of the optical disc 1 changes according to the tilt of the optical disc 1 is calculated.

The optical disk 1 without tilt is set parallel to the xy plane, the y-axis direction is the radial direction, and the x-axis direction is the tangential direction. Radial tilt and tangential tilt are θx and θy. Further, it is assumed that the incident light is incident on the yz plane at an angle of θi with respect to the y axis.

Accordingly, the angle of the component formed by projecting the reflected light beam in the xy plane and the component projected on the yz plane with the y axis is φx
, φy, Equations 1 and 2 are obtained.

[0045]

(Equation 1)

[0046]

(Equation 2)

Here, for the sake of simplicity, considering the case where there is no tangential tilt and only a radial tilt exists, that is, the case where θx = 0, φy = θi−2θy, and when there is a radial tilt as an angle component, Is twice as large.

When there is no radial tilt and only tangential tilt exists, that is, when θy = 0, tanφy = −cos 2θx * tanθi, and when the tilt amount is small, that is, when θx and φx are small, φx = -2θ
x * tanθi. In this case, the sensitivity to tilt angle is
It turns out that it becomes tanθi times.

From these results, it can be seen that the amount of change in the emission angle of the reflected light beam of the optical disk 1 according to the tilt of the optical disk 1 depends on the incident angle of the light beam incident on the optical disk 1. Therefore, the movable part of the actuator
In order to detect the relative tilt amounts of the tangential direction and the radial direction between the optical disk 14 and the optical disk 1, it is necessary to make the incident angle of the light beam on the reflective mirror 15 of the actuator movable section 14 equal to the incident angle on the optical disk 1. . That is, the reflecting mirror is proportional to the amount by which the movable part 14 of the actuator is tilted.
The change amount of the exit angle 15 needs to be the same change amount of the angle when the light is reflected by the optical disc 1.

When the photodetector 20 detects the tilt amount in the tangential direction and the radial direction,
What is necessary is just to use a quadrant detector. Note that a configuration using two-dimensional semiconductor position detection may be used.

In order to detect the amount of tilt in the tangential direction and the radial direction, as shown in FIG.
The phase is compensated at 22 and the compensation is input to the actuator drive circuit 23. The actuator drive circuit 23 drives the actuator only in the radial direction of the optical disc 1 or in the radial and tangential directions, and moves the objective lens 8 to the optical disc 1 in accordance with the tilt amount of the optical disc 1 in the radial and tangential directions. 1. Tilt and tilt control in the radial and tangential directions are performed.

Further, when the incident angle θ1 of the light beam to the reflecting mirror 15 is 60 degrees, as shown in FIGS. 6, 1 and 2, the light beam from the tilt detecting light source 16 is transferred to the actuator movable section. It is possible to adopt a configuration in which the light is perpendicularly incident on.

The tilt detecting light source 16 and the convex lens 17,
Although the tilt amount can be detected by a configuration in which the photodetector 20 and the convex lens 19 are exchanged, in this case, a configuration of a light beam emitted perpendicular to the actuator movable section 14 can be adopted.

Then, the light beam is transmitted to the actuator movable section.
In the configuration in which the light enters or exits perpendicularly to the optical disk 14, even if the actuator movable section 14 is shifted in the focus direction, an optical disk device that is resistant to vibration can be provided without affecting the incident system or the detection system.

The arrangement of the tilt detecting light source 16 and the convex lens 17 and the arrangement of the photodetector 20 and the convex lens 19 are limited by the optical head 50. If the light beam cannot be arranged at the position where the light is emitted, the stop of the light beam at the convex lens 17 may be suppressed and a thicker light beam may be used.

Thus, even if the actuator movable section 14 is displaced in the focus direction, a part of the light beam
The light is reflected at 15, and the tilt amount can be detected by this light beam.

Next, FIG. 7 shows a schematic configuration of an optical disk device according to the second embodiment of the present invention. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 7 shows an example in which a total reflection mirror 31 is used instead of the reflection mirror 15 provided in the actuator movable section 14 in FIG.

This is because when the light beam incident on the reflection mirror 15 has a total reflection angle or more, the total reflection mirror can be used.

The total reflection angle ic is represented by sin ic = 1 / n. Usually, the refractive index n is about 1.51 for glass, and in this case, the total reflection angle ic = 41.47 °.

In this embodiment, since the angle of incidence on the reflection mirror 15 is 60 °, which is larger than the total reflection ic, a total reflection mirror 31 can be used instead of the reflection mirror 15. it can.

Also in this case, the light beam from the tilt detecting light source 16 can be vertically incident on the actuator movable section 14 as in FIG. This is because, as described with reference to FIG. 6, if the incident angle θ1 is an angle of 60 degrees, the light beam from the tilt detection light source 16 can be perpendicularly incident on the actuator movable unit 14, and the total reflection mirror can be used. 31 can be used.

Further, unlike the reflection mirror 15, the total reflection mirror 31 has an advantage that the coating of the reflection film is unnecessary and the manufacturing cost of parts is reduced.

FIG. 8 shows an example in which the reflecting mirror 15 of FIG. 1 is integrally formed as a part of the objective lens 8 to form an objective lens integrated mirror 32.

In this case, the cost of parts can be further reduced by integrally forming the mirror with the objective lens.

Next, FIG. 9 shows a schematic configuration of an optical disk device according to a third embodiment of the present invention. The same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 9, the functions of the tilt detection light source 16, the convex lenses 17 and 19, and the photodetector 20 of FIG. 1 are summarized, and the tilt detection light source 41, the photodetector 42 and the lens function (the tilt detection light source 41 (Which collimates the light beam from the device) is integrated as an integrated device. Among them, the tilt detection light source 41 is fixed to the light source base 410, and the light source base 410, the photodetector 42, and the element 43 are fixed to the integrated element base 420.

The element 43 having a lens function includes:
A convex lens or a diffraction element may be used.

In FIG. 1, a mirror 44 is provided instead of the mirror 18 and the convex lens 19 for guiding the light beam of the tilt detecting light source 16 reflected by the optical disk 1 to the photodetector 20.

Note that the mirror 44 is an element having a light-condensing function, but it is sufficient that the light beam reflected by the optical disk 1 is condensed on the photodetector 42, and a mirror having a concave surface or a reflective element is used. You may.

If an integrated element is used, the size of the light source and the detection system can be further reduced, and the size of the optical disk device itself can be further reduced.

Next, FIG. 10 shows a schematic configuration of an optical disk device according to a fourth embodiment of the present invention. 1 and 9
The same reference numerals are given to the same elements as those described above, and description thereof will be omitted.

In FIG. 10, as in FIG. 9, the tilt detection light source 51 and the photodetector 55 are integrated as an integrated element. In addition, the diffraction element 53 is an integrated element instead of the element 43 of FIG. Here, the diffractive element 53 uses the returned light beam as a lens
Is an element having an action of leading to Among them, the tilt detection light source 51 and the photodetector 55 are arranged close to each other, and the photodetector 55 and the diffraction element 53 are fixed to the integrated element base 420.

The direction of the light beam from the tilt detection light source 51 is changed by a mirror 52 and collimated by a diffraction element 53. Next, the light is reflected by the reflection mirror 15 of the actuator movable section 14 via the optical path 900, and further reflected by the optical disk 1. After that, the light is reflected not by the actuator movable part 14 but by the mirror 54 provided on the fixed part 501, reflected again by the optical disk 1, reflected by the reflecting mirror 15, and again reflected by the diffraction element 5
Enter 3. This light beam is condensed by the diffractive element 53, and the direction of the light beam is changed by the mirror 52 onto the photodetector 55. The mirror 52 is also fixed to the integrated element base 420.

In the case of the configuration shown in FIG.
The light is reflected twice by the reflection mirror 15 of the actuator movable section 14, and the sensitivity of tilt detection is doubled as compared with the cases of FIGS. 1 and 7 to 9. This is because the number of reflections is doubled.

In place of the diffractive element 53, an element having a light condensing function such as a convex lens may be used. in this case,
It is necessary to arrange the mirror 54 at a position where the light beam from the reflection mirror 15 is deflected to the photodetector 55.

According to the present invention, the tilt amount of the optical disk can be accurately detected by a simpler and more accurate tilt sensor, and the coma generated by the tilt of the optical disk can be reduced. Also, a small light beam can be realized with the objective lens. Therefore, stable recording or reproduction can be performed even in an optical disk device of high density by shortening the wavelength of a high NA objective lens or light source.

In the above-described embodiment, the method of compensating the tilt amount of the optical disk has been described with the method of tilting the objective lens. However, the method of tilt compensation is not necessarily limited to the method of tilting the objective lens. For example, a method of tilting the entire optical head, a method of tilting the optical disk, a method of compensating the phase of a light beam incident on the objective lens using a liquid crystal element, or the like may be used. And in this case,
A device or an element to be driven for tilt compensation in each of the above-described methods may be driven based on a signal obtained by detecting a tilt amount.

[0079]

As described above, according to the optical disk apparatus of the present invention, the effect that the amount of tilt can be detected accurately can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining a tilt detection method according to the present invention.

FIG. 3 is a diagram showing a detector surface of a photodetector according to the present invention.

FIG. 4 is a diagram showing a detector surface of a photodetector according to the present invention.

FIG. 5 is a diagram for explaining tilt control according to the present invention.

FIG. 6 is a diagram for explaining tilt control according to the present invention.

FIG. 7 is a schematic configuration diagram of an optical disc device according to a second embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of an optical disc device showing a modification of the second embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of an optical disc device according to a third embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of an optical disc device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 Optical disk 2 Spindle motor 3 Light source 4, 20, 42, 55 Photodetector 5 Collimating lens 6 Beam splitter 7 Start-up mirror 8 Objective lens 9, 18, 44, 52, 54 Mirror 10 Detection lens 11, 21 Arithmetic circuit 12, 22 Phase compensation circuit 13, 23 Actuator drive circuit 14 Actuator movable part 15 Reflection mirror 16, 41, 51 Tilt detection light source 17, 19 Convex lens 31 Total reflection mirror 32 Objective lens integrated mirror 43 Element 50 Optical head 53 Diffractive element 201 Dividing line 210 Semiconductor position detecting element 211, 212 Electrode 410 Base for light source 420 Integrated element base 501 Fixed part 900 Optical path 1000 Through hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Noriyuki Ishibashi 70, Yanagimachi, Yuki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagicho Plant Co., Ltd. F-term in the factory (reference) 5D118 AA14 BA01 CD04 CG03 CG07 CG26

Claims (11)

[Claims] 1. An optical disc for irradiating a light beam to an optical disc for detecting a tilt of the optical disc in which information is reproduced by condensing and irradiating a light beam from a first light source with an objective lens. A second light source; optical means for irradiating the optical disk with a light beam from the second light source; and light detection for detecting reflected light of the light beam irradiated by the optical means from the optical disk Means for reflecting the beam from the second light source, and irradiating the light on the optical disk near a position where the light beam from the first light source is irradiated, An optical disc apparatus, wherein a light beam from a second light source is detected by the light detecting means after the same number of times of reflection between the optical means and the optical disc. 2. The optical disk device according to claim 1, wherein the number of reflections is plural. 3. A method for detecting a tilt of an optical disc on which information is reproduced by focusing and irradiating a light beam from a first light source with an objective lens of an objective lens holding means for holding an objective lens. A second light source for irradiating the optical disk with a light beam; and reflecting the light beam from the second light source, and irradiating the optical beam with the light beam from the first light source of the optical disk. A light beam reflecting means provided on the objective lens holding means for irradiating the vicinity of the position where the light beam is located; An optical disk device comprising: 4. An incident angle of the light beam from the second light source to the light beam reflecting means and an incident angle of the light beam from the second light source to the optical disk by the light beam reflecting means are equal. The optical disk device according to claim 3, wherein 5. An incident angle from the second light source to the light beam reflecting means, and an incident angle of the light beam from the second light source to the optical disk by the light beam reflecting means is 60 degrees. The optical disk device according to claim 4, wherein: 6. A light beam from the second light source is detected by the light detection means after the same number of times of reflection on the light beam reflection means and the optical disk. Item 5. The optical disk device according to item 4. 7. The optical disk apparatus according to claim 6, wherein the number of times of reflection is equal to the number of times of the light beam reflecting means and the optical disk, and the number of times of reflection is a plurality of times. 8. The apparatus according to claim 3, wherein said objective lens holding means has a hole for irradiating said light detecting means with a light beam from said second light source reflected by said optical disk. An optical disk device according to claim 4. 9. The light beam reflecting means according to claim 3, wherein the light beam from the second light source is totally reflected.
An optical disk device according to claim 4. 10. The optical disk apparatus according to claim 3, wherein said light beam reflecting means is provided integrally with said objective lens holding means. 11. The optical disk device according to claim 3, wherein said second light source and said light detecting means are integrated in one element.