JP2002092906A - Optical recording and/or reproducing device and optical recording and/or reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the collision of an objective lens with a defective projecting part on an optical recording medium when making the objective lens having a high numerical aperture approach a medium surface to record an information signal in high density. SOLUTION: A laser element 4 emits a laser beam for recording the information signal on a glass master disk 16. The aspherical lens in an optical head 15 condenses the laser beam from the laser element 4 onto the glass master disk 16. A SIL(Solid Immersion Lens) in the optical head 15 realizes a larger numerical aperture than the numerical aperture of the aspherical lens. A laser element 21 emits a laser beam for disturbance detection onto the glass master disk 16. A focus controller 33 holds the distance between the end surface 45 of the SIL 44 and the glass master disk 16 constant. The optical head protecting device 35 protects the SIL 44 and the glass master disk 16 on the basis of a light beam returning from the glass master disk 16 originating from the laser beam emitted from the laser element 21 and condensed on a position preceding a position on which the SIL 44 condenses the laser beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording and / or reproducing apparatus and an optical recording and / or reproducing method capable of recording and / or reproducing information by irradiating an optical recording medium with light, and more particularly to an optical recording and / or reproducing method. The present invention relates to an optical recording and / or reproducing apparatus and an optical recording and / or reproducing method for recording and / or reproducing information signals at a high density by bringing an objective lens having a high numerical aperture close to a medium surface.

[0002]

2. Description of the Related Art In order to perform recording and / or reproduction using near-field light, a solid immersion lens (solid immersion lens, SIL) and a condensing lens for injecting a laser beam into the SIL are required. , A total of two lenses (hereinafter,
Two groups) are used in combination. This was conceived to further reduce the spot diameter in response to the need for higher density optical disks. This is because a numerical aperture larger than the numerical aperture of the condenser lens itself can be realized by interposing the SIL between the condenser lens and the optical disk. The SIL is a high-refractive-index lens having a shape obtained by cutting off a part of a spherical lens.
It is arranged with its opposite surface facing the optical recording medium.

In order to perform optical information recording and optical information reproduction using the near-field signal by the SIL, a recording laser is focused on the end surface of the SIL, and the near-field light is generated at a distance between the SIL end surface and the optical recording medium. Distance (less than half of light wavelength,
(Typically about 200 nm or less), and focus control is required to keep the distance constant and to keep the converging spot on the optical recording medium constant.

However, when the distance between the SIL end face and the optical recording medium is reduced to a distance at which near-field light is generated, if dust (projection defect) having a height higher than the above-mentioned distance is present on the optical recording medium, the SIL end face will be lost. Collide with the convex portion, and the focus control itself becomes impossible. Also, if there is dust (convex defect) having a height equal to or less than the above-described distance on the optical recording medium, or if there is a scratch or dent (concave defect) on the surface of the optical recording medium, it becomes a factor of disturbance to the focus servo and causes a focus. The servo becomes unstable, and there is a risk that the SIL end face collides with the optical recording medium. Further, it is very difficult to completely remove a convex defect or a concave defect on the optical recording medium from the optical recording medium.

[0005] Therefore, in order to perform optical information recording and / or reproduction using the near-field signal by the SIL, the SIL end face and the optical recording medium must be connected to each other due to a convex defect or a concave defect on the optical recording medium. It is necessary to provide a means for avoiding collision.

In a typical technology of this type of optical recording and / or reproducing apparatus, before performing optical information recording and / or reproduction using the near-field signal by the above-mentioned SIL, the distance between the SIL end face and the optical recording medium is changed. There is a method in which a convex defect having a height equal to or larger than the gap control distance is shaved in advance. This is performed by scanning the entire optical recording medium with a hard head fixed to the distance or less. The above method is called burnishing, and is used as a means for avoiding collision between a magnetic head and an optical recording medium in magnetic recording. With this method,
It is possible to deal with a convex defect on the optical recording medium.

As a method for keeping the distance between the SIL end face and the optical recording medium constant, there is a method using an air bearing slider. In this method, a two-group lens is mounted on a slider,
By rotating the optical recording medium, an air film is generated between the optical recording medium and the second group lens provided on the slider, and the second group lens is floated by the pressure of the air film, so that the SIL end face and the optical recording medium can be recorded. It keeps the distance to the medium constant and does not require a servo. By not performing the servo, the SIL caused by the servo responding to a convex and concave defect (hereinafter, referred to as a defect) on the optical recording medium is caused.
Collision with the optical recording medium can be avoided. Therefore, even if there is a defect in the optical recording medium, the disturbance due to the defect makes the servo unstable and the SIL end face does not collide with the optical recording medium.

Further, a solid or liquid lubricant is applied to the outermost surface of the optical recording medium on which light is incident, and a lubricating layer is provided to increase the depth of focus. In comparison, it is possible to increase the distance between the SIL end face and the optical recording medium while maintaining the same focused spot,
There is also a method in which dirt, scratches and dust on the optical recording medium are included in the lubricating layer. Thus, even when a defect exists in the optical recording medium, it is possible to avoid the danger that the SIL end face collides with the optical recording medium.

[0009]

However, these prior arts have the following problems. First, the method using burnishing is based on the premise that the medium to be burnished is hard and dry,
Discs coated with a resist film used in the manufacture of discs, such as DVDs and DVDs, are unsuitable because their surfaces are soft and sticky. That is, when there is a convex defect having a height equal to or larger than the gap control distance between the SIL end face and the optical recording medium on the disk, the convex defect collides with a hard fixed head used for burnishing, and the convex defect is formed. At the time of grinding, the resist adheres to the fixed head, and normal burnishing becomes impossible. Also, even if you can remove it,
There is a danger that the stripped resist rolls on the disk surface, damaging the disk surface and causing a new defect.

Second, the method using the air bearing slider is based on the premise that the optical recording medium is rotated, and the SIL end surface is in contact with the optical recording medium before the rotation of the optical recording medium. Therefore, in a disk coated with a resist film used in manufacturing a disk such as a CD or a DVD, the SIL end surface comes into contact with the disk, and the disk is damaged. Further, the distance between the SIL end face and the optical recording medium is equal to or less than the desired value until the distance between the SIL end face and the optical recording medium reaches a desired value. Risk of wear or damage to the surface of the

In the third method, the lubricant is applied to the outermost surface of the optical recording medium on the side where light is incident. Even if the depth of focus is increased, if there is a defect equal to or greater than the depth of focus, the SIL end face is also required. There is a danger that the optical recording medium will collide with and cause wear or damage to the end surface of the SIL or the surface of the optical recording medium. Further, this method is based on the premise that a lubricating layer is provided on the outermost surface of the optical recording medium on the side where light is incident. Therefore, this method is applied to a disk coated with a resist film used in manufacturing disks such as CDs and DVDs. Is inappropriate.

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and when an information lens is recorded and / or reproduced at a high density by bringing an objective lens having a high numerical aperture close to a medium surface.
An optical recording and / or reproducing apparatus capable of preventing the objective lens from colliding with a defect or the like on the optical recording medium and protecting the objective lens and the optical recording medium from wear or damage;
And an optical recording and / or reproducing method.

[0013]

SUMMARY OF THE INVENTION An optical recording and / or reproducing apparatus according to the present invention provides a recording / reproducing light for recording / reproducing an information signal on / from an optical recording medium in order to solve the above-mentioned problems. A first light source that emits light, and a first light source that condenses recording / reproducing light from the first light source to irradiate the optical recording medium.
Optical means, a second optical means interposed between the first optical means and the optical recording medium to realize a numerical aperture larger than the numerical aperture of the first optical means, A second light source for emitting light different from the recording / reproducing light to the recording medium, and control means for maintaining a constant distance in the near-field region between the end face of the second optical means and the optical recording medium And the second optical means performs the recording /
The second optical means, based on the return light of the optical recording medium, of the light from the second light source focused on a position preceding the position on the optical recording medium on which the reproduction light is focused, Protection means for protecting the optical recording medium.

In order to solve the above problems, the optical recording and / or reproducing method according to the present invention provides a recording / reproducing method for recording / reproducing an information signal on / from an optical recording medium from a first light source.
In order to realize a numerical aperture larger than the numerical aperture of the first optical means for converging the reproduction light to irradiate the optical recording medium, a first optical means interposed between the first optical means and the optical recording medium is realized. A control step of maintaining a constant distance in the near field area between the optical recording medium and the end face of the optical recording medium, and the light from the second light source that emits light different from the recording / reproducing light is emitted from the second light source. And a protection step of protecting the second optical unit and the optical recording medium from disturbance information obtained by irradiating a disturbance generated on the optical recording medium.

In the optical recording and / or reproducing apparatus and method, the protection control signal output from the protection means and the protection step and the focus control signal output from the control means and the control step are converted to the second control signal. Switching or concurrent use is performed based on the amount of light returned from the optical means. Specifically, by providing the control voltage output means and the control voltage output step, the protection control output by the protection means and the protection step based on the amount of the recording / reproducing light returned from the second optical means. The signal is combined with the focus control signal output by the control means and the control step and output, or is output alone.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, the optical recording and / or
Alternatively, a specific example of the optical recording device in the reproducing device will be described. In this specific example, the optical recording method of the optical recording and / or reproducing method of the present invention can be applied.

A specific example of this optical recording apparatus is a cutting machine shown in FIG. 1, which is called a cutting machine that cuts and records information by irradiating a laser beam modulated in accordance with information on the surface of a glass master coated with a resist. It is a recording device.

First, the configuration of the main part of the optical recording apparatus will be described. This optical recording apparatus has a laser element 4 (laser element 4) for emitting a recording laser beam for recording an information signal on a glass master 16 coated with a resist.
1) and an optical head 15 for condensing the recording laser light from the laser element 4 so as to irradiate the glass master 16.
An aspheric lens 43 shown in FIG. 2 described below and an optical head 15 interposed between the aspheric lens 43 and the glass master 16 in order to realize a numerical aperture larger than the numerical aperture of the aspheric lens 43 A solid immersion lens (SIL) 44 shown in FIG. 2 to be described later, and a laser element (laser 2) for emitting a disturbance detection laser beam different from the recording laser beam to the glass master 16 21, the end face 45 of the SIL 44 and the glass master 1
A focus control device 33 for maintaining a constant distance in the near-field region between 6 and the laser light from the laser element 21 focused at a position preceding the position at which the SIL 44 focuses the laser light for recording. An SIL 44 and an optical head protection device 35 for protecting the glass master 16 based on the return light from the glass master 16 are provided as main parts.

The optical recording apparatus further includes an optical head protection control voltage 36 for the optical head protection device 35, which will be described later, based on the amount of the returning laser light from the SIL 44.
A control voltage synthesizing unit 37 that synthesizes and outputs a later-described focus control voltage 34 of the focus control device 33 or outputs the synthesized voltage alone is also provided as a main part.

Next, the overall configuration of the optical recording apparatus shown in FIG. 1 will be described while clarifying the relationship between the main part and its peripheral parts. The recording laser beam LB1 emitted from the laser element 4 (laser 1) is converted into an electro-optical conversion element (EO).
M) 5, the light enters the acousto-optic element (AOM) 3 via the analyzer 6 as a polarizing plate and the beam splitter (BS) 7, and is then modulated in the AOM 3. AOM
The information from the information source 1 is also digitized by the recording signal generator 2 and input to the information source 3, and modulates the recording laser beam LB1 according to the recording information.

The laser beam LB2 modulated and output by the AOM 3 is reflected by the mirror 10a, passes through the condenser lens 55, is converted into a parallel beam by the collimator lens 11, and passes through the polarizing beam splitter (PBS) 12. Then, the light enters the λ / 4 plate 13.

The modulated light LB3 that has passed through the λ / 4 plate 13 is
The light becomes circularly polarized light and is input to the dichroic mirror 14.
The dichroic mirror 14 has a wavelength of LB3.
It has the property of transmitting light.

The modulated light LB4 transmitted through the dichroic mirror 14 is reflected by the mirror 10b, and then reflected by the optical head 15
Is incident on. The optical head 15 irradiates the circularly polarized laser light onto the glass master 16 coated with the resist in a spot shape. At this time, the focus of the optical head 15 on the glass master 16 is controlled by the focus control device 3.
3 and the gap with the glass master 16 is kept constant.

The laser beam LB4 incident on the optical head 15
Is a glass master 1 on which a light spot is coated with a resist while the size is controlled to be constant by the focus control device 33.
6 is formed. The resist applied to the glass master 16 is cut by the light spot according to the recorded information.

A part LB8 of the recording laser beam from the laser element 4 passes through the EOM 5 and the analyzer 6 and passes through the BS
7, and is detected by the photodetector (PD1) 8. The laser beam LB8 incident on the PD (1) 8 is converted into an electric signal, input to an automatic power controller (APC) 9, and the value is fed back to the EOM 5, whereby the power of the laser element 4 is controlled to be constant. Therefore, AP
The light amount after C is a constant amount, and becomes the maximum light amount 19.

On the other hand, the return light from the optical head 15 for the laser light LB4 transmitted through the dichroic mirror 14 is:
After passing through the dichroic mirror 14 again and being converted into linearly polarized light through the λ / 4 plate 13, the PBS 12 and the mirror 1
The light is reflected at 0 c and input to the condenser lens 17. The return light LB5 that has passed through the condenser lens 17 is input to a photodetector (PD2) 18 and detected as a return light amount 20.

The focus controller 33 receives a constant maximum light amount 19 and a return light amount 20 from the optical head 15. The focus control device 33 generates a reference signal based on the maximum light amount 19 that is a fixed amount, and
The focus control voltage signal 34 is output using the return light amount 20 from the control unit as the controlled amount. Then, the focus control device 33 controls the focus of the optical head 15 using the focus control voltage signal 34 so that the gap between the optical head 15 and the glass master 16 is constant. The details of the focus control operation by the focus control device 33 are disclosed in Japanese Patent Application No. 11-253296 filed by the present applicant. Details of the focus control operation will be described later.

Although the focus controller 33 uses the maximum light amount 19, which is the constant light amount, as the signal source for generating the reference signal, a signal generated by a constant voltage source may be used.

On the other hand, a laser element (laser 2) 21
Unlike the laser element (laser 1) 4 for the recording laser, the laser is used to detect disturbance due to a convex defect on the glass master 16 and has a wavelength at which the resist applied on the glass master 16 is not exposed. Generates laser light.

The laser light emitted from the laser element (laser 2) 21 is converted into an electric-optical conversion element (EOM) 22
Then, the light passes through an analyzer 23 which is a polarizing plate, is reflected by a beam splitter (BS) 24 to become a laser beam LB6, is bent by a mirror 10d, and then enters a condenser lens 54. The condensing lens 54 condenses the laser beam LB6 and then enters the collimator lens 27.

The collimator lens 27 converts the laser beam LB6 into a parallel beam, and forms a parallel beam splitter (PB).
S) passes through 28 and is input to the λ / 4 plate 39. The light after passing through the λ / 4 plate 39 becomes circularly polarized light, and the laser light LB7
Then, the light is reflected by the mirror 10 e and enters the dichroic mirror 14.

The dichroic mirror 14 has a laser beam LB
The laser beam LB7 is reflected by the mirror 7 and is also reflected by the mirror 10 to become a laser beam LB11. The laser beam LB7 is applied to the glass master 16 via the optical head 15. Laser beam LB11
Of the laser beam LB4 is different from the irradiation position of the laser beam LB4. The actual irradiation position will be described later.

A part LB10 of the laser beam emitted from the laser element 21 for detecting a disturbance is
Then, the light passes through the analyzer 23, passes through the BS 24, and is detected by the photodetector (PD 4) 25. PD (4)
The laser beam LB10 incident on 25 is converted into an electric signal, input to an automatic power controller (APC) 26, the value of which is fed back to the EOM 22, and the power of the laser element (laser 2) 21 is controlled to be constant. Therefore, the amount of laser light after APC is constant.

On the other hand, the return light from the optical head 15 for the laser light LB11 is reflected at a right angle by the mirror 10, then reflected by the dichroic mirror 14, and reflected by the mirror 10
e, after being converted to linearly polarized light through the λ / 4 plate 39,
After being reflected vertically by S28 and reflected again by the mirror 10f, it is input to the condenser lens 29. The laser beam LB9 passing through the condenser lens 29 is converted into a photodetector (PD)
3) input to 30 and as the preceding beam return light quantity 31
It is input to the optical head protection device 35.

In addition to the preceding beam return light amount 31, a rotation-synchronized FG signal 32, which is a fixed number of pulse trains per rotation, is input to the optical head protection device 35. By the FG signal 32, the glass master 1 having the preceding beam returning light amount 31
The detection position on 6 is specified, and the disturbance detection result based on the preceding beam return light amount 31 and its position signal are stored in the memory in the optical head protection device 35 prior to recording.

The control voltage synthesizing section 37 reads out the disturbance detection result stored in the memory in the optical head protection device 35 prior to the recording position, and focuses so as to eliminate the influence of the disturbance based on the read value. The control voltage 34 is corrected, and the final focus control voltage 38 is output. The optical head 15 receiving the final focus control voltage 38
According to the method, even if there is a convex defect on the glass master 16, the resist can be stably cut for a long time without colliding with the glass master 16 due to disturbance. Details of this operation will be described later.

FIG. 2 is an enlarged view of the optical head 15 used in this embodiment. The optical head 15 is composed of two parts (two-group lens): an aspheric lens 43 as first optical means and a solid immersion lens (SIL) 44 as second optical means. This two-group lens is attached to the piezo element 42. A condenser lens 40 is provided above the second lens group.
And a collimation lens 41 are provided.

The SIL 44 is a high-refractive-index lens having a shape in which a part of the lens is cut out. The SIL 44 is arranged with the spherical surface 44a facing the aspherical lens 43 and the opposite surface 44b facing the glass master disk 16. . A central portion of the surface 44b is a convex portion, and a flat end surface 45 is formed on the convex portion. This end face 45 comes closest to the glass master 16.
By interposing the SIL 44 between the aspheric lens 43 and the glass master 16, a numerical aperture larger than the numerical aperture of the aspheric lens 43 itself can be realized. Thereby, the spot diameter can be further miniaturized corresponding to the need for high density.

The light LB4 incident on the second group lens is condensed by the aspheric lens 43 and enters the SIL 44. SIL
Of the laser light LB4 incident on the light 44, the light incident at an angle equal to or greater than the angle at which total reflection occurs is totally reflected within the SIL 44, and does not exit outside the SIL 44. However, the distance at which near-field light is generated (generally, a distance of about half or less of the wavelength of light) is S
When the end surface 45 of the IL 44 approaches the glass master 16, evanescent coupling occurs, and a part of the light that has been totally reflected becomes
As a near-field light, it oozes out into the glass master 16 and becomes SIL 44
The light enters the glass master 16 from inside. Part of the near-field light that has entered the glass master 16 is reflected on the surface of the glass master 16 and returns to the SIL 44 again. The reflected light from the SIL 44 is used as a controlled amount and the focus control device 33
The gap between the end face 45 of the SIL 44 and the glass master 16 is controlled to be constant. The glass master 1 is used as near-field light.
The information is recorded on the glass master 16 by the laser beam LB 4 leached into the glass master 6. A control method for controlling the gap between the end surface 45 of the SIL 44 and the glass master 16 to be constant is disclosed in Japanese Patent Application No. 11-253296 as described above.

On the other hand, unlike the recording laser beam LB4, the laser beam LB11 incident on the second group lens for detecting a disturbance is different in the incident direction and the emission direction. First, the incident light LB11-1 is incident on the aspherical lens 43 in a condensing tendency by the condensing lens 40 having a low NA (for example, NA = 0.1) installed above the second lens group, and is refracted. , SIL41. After being further refracted by the SIL 44, it is condensed on the glass master 16. This focal point is a position different from the focal point of the recording laser beam LB4. A part of the light condensed on the glass master 16 is reflected on the surface of the glass master 16 and SIL4
The light passes through the fourth lens 4 and the aspherical lens 43 and returns through a different path from the incident light. The return light is converted into a parallel beam LB11-2 by the collimation lens 41, and then the dichroic mirror 14, the λ / 4 plate 39, the PBS 28,
And a photodetector (PD) via the condenser lens 29
3) Lead to 30 and detect.

The laser beam LB11 is a laser beam for detecting disturbance due to a convex defect on the glass master 16 prior to recording, and has a longer wavelength than the laser beam LB4 for recording information. The resist applied on the substrate 16 is not exposed. In addition, since the laser beam LB11 is condensed on the glass master 16 by the condensing lens 40 having a low NA, the depth of focus is large and no focus control is required. Further, even if the optical head 15 itself moves by the optical head protection operation, it is possible to stably detect the disturbance due to the defect on the glass master 16.

Next, the focus control operation by the focus control device 33 will be described in detail. This focus control operation is clarified as described below in Japanese Patent Application No. 11-253296 filed by the present applicant.

FIG. 3 shows the return light LB11 from the SIL 44.
-2 when the PD (2) 18 detects the light intensity (return light amount)
(V) 20) and an example showing the relationship between the SIL 44 and the distance between the glass master 16. In this example, SIL44
When the glass plate 16 is 200 nm or more, the near-field light is not generated and is totally reflected, so that the return light LB11−
The strength of No. 2 is constant. However, at a wavelength of 200 nm or less, a part of the light incident on the SIL 44 is transmitted as near-field light to the glass master 16, so that the intensity of the return light from the SIL 44 decreases. When the SIL 44 comes into contact with the glass master 16, all the light incident on the SIL 44 passes through the glass master 16, and the intensity of the return light from the SIL 44 becomes zero (0.0).

FIG. 3 shows that the SIL 44 and the glass master 16
It can be seen that there is a one-to-one relationship between the distance between the SIL and the SIL return light amount. In this relationship, if the linear region is used, the distance can be easily controlled to the control target value.

As described above, in the present invention, the light quantity (V) 20 of the return light of the SIL 44 is used as a control amount for controlling the distance between the SIL 44 and the glass master 16 to be constant. As a driving means for changing the distance between the SIL 44 and the glass master 16, a piezo element 42 capable of converting an electric signal into a positional displacement on the nano order is used. As shown in FIG. Aspherical lens 43 and S
The focus control voltage 38 is applied to the piezo element 42 so that the distance between the SIL end face 45 and the glass master 16 is constant by moving the second group lens according to the return light amount 20. In this embodiment, 1
The SIL 44 is made to approach the glass master 16 by applying a voltage to the piezo element 42 using the piezo element 42 which is displaced by 12 nm at 50 V.

Next, the positions of the condensed spots of the recording laser beam LB4 and the laser beam LB11 for detecting disturbance on the glass master 16 will be described.
FIG. 4 shows a position where a condensed spot 46 (hereinafter referred to as a recording spot) formed by a recording laser beam LB4 and a condensed spot 47 (hereinafter referred to as a preceding beam spot) formed by a laser beam LB11 for detecting disturbance. FIG. 5 is a diagram showing a position where the optical head 15 is positioned, and is a diagram when the optical head 15 is viewed from above. The recording spot 46 is focused on the center of the SIL end face 45. One preceding beam spot 47 is formed ahead of the traveling direction of the recording spot 46 (recording direction (tangential direction) 48).

The preceding beam spot 47 of the laser beam LB11 precedes the recording spot 46 and detects in advance the disturbance due to the convex defect at the recording location, and the convex defect is directly directed to the SIL end face 45 which is a part of the optical head. It is used for the purpose of preventing the SIL end face 45 from colliding with the disk due to collision or unstable focus control due to disturbance due to a convex defect.

In the case of near-field optical recording, the distance between the recording spot 46 on the glass master 16 and the SIL end face 45 is SIL
It is constant over the entire end face 45. Therefore, even on the glass master 16 other than the recording spot 46, the SIL end face 45
If there is a convex defect in the portion covered by the defect, the convex defect may directly collide with the SIL end face 45, or the focus control may become unstable due to disturbance due to the convex defect, and the SIL end face 45 may collide with the disk.

Therefore, at least the SIL is located in front of the recording direction (tangential direction) 48 and in the recording direction (radial direction) 49.
It is necessary to detect a disturbance due to a convex defect on the glass master 16 based on the diameter width of the end face 45. For this purpose, the preceding beam spot 47 is at least SI
At least one point needs to be arranged at a distance in front of the L end face 45 by a radius or more (on the right side of the boundary 50 of the preceding beam spot arrangement).

Alternatively, apart from the preceding beam spot forming method, as shown in FIG. 5, a plurality of condensed spots by the laser beam LB11 are arranged in the recording direction (radial direction) 49 and the main beam train is recorded. A convergent spot array (hereinafter, referred to as a preceding beam spot array) 52 by the laser beam LB11 may be formed by being disposed ahead of the traveling direction (recording direction (tangential direction) 48) from the position where the spot 46 is formed.

In the case of this method, the preceding beam spot train 5
2 can be formed as shown in FIG. That is, the grating 51 is arranged at a focal position between the condenser lens 54 and the collimator lens 27 through which the light LB6 emitted from the laser element (laser 2) 21 passes, and LB6 is divided into a plurality of beam arrays. And the collimator lens 2
7 pass through the PBS 28 and the λ / 4 plate 39 and become circularly polarized light.
4 and is incident on the optical head 15 and is formed on the glass master 16 as the preceding beam spot row 52 shown in FIG.

In this case, the preceding beam spot row 52 is at least SI
It is necessary that at least one point is disposed at a distance in front of the L end face 45 by a radius or more (above the boundary line 53 of the preceding beam spot row arrangement).

As described above, the preceding spot 47 or the preceding beam spot row 52 is arranged as shown in FIG. 4 or FIG.
It is possible to detect a disturbance due to a convex defect that may collide with the SIL end surface 45 before recording information on the SIL.
Then, based on the detected disturbance information, the SIL end face 45 is
Can be prevented from colliding with the glass master 16.

Hereinafter, taking the case where the preceding beam spot 47 is formed as shown in FIG. 4 as an example, the prevention of the collision of the SIL end face 45 with the glass master 16, that is, the protection operation of the SIL end face 45 and the glass master 16 will be described in detail. explain.

FIG. 7 shows the optical head protection device 3 shown in FIG.
FIG. 5 is a diagram showing an internal structure of a fifth embodiment. This optical head protection device 3
Reference numeral 5 denotes a signal calibrating unit 55 for calibrating the preceding beam returning light amount 31, a low-pass filter (LPF) 57 for passing a low band component of the preceding beam returning light amount 31 calibrated by the signal calibrating unit 55, and the preceding beam A disturbance determination unit A56 that determines the presence or absence of a disturbance from the return light amount 31;
A disturbance determining unit B58 for determining the type of disturbance from the filtering output of the above, a disturbance determining unit A56 and a disturbance determining unit B58
A disturbance determination data generation unit 59 for generating disturbance determination data from the determination output of the above, a memory 63 for storing the disturbance determination data generated by the disturbance determination data generation unit 59, and a write timing of the disturbance determination data to the memory 63 Write timing control unit 60 for controlling
A memory read timing control unit 61 for controlling the timing of reading the disturbance determination data from the memory 63
And an optical head protection controller 62 for adjusting the gain of the disturbance determination data read from the memory 63. The optical head protection device 35 performs an optical head protection operation using the preceding beam return light amount 31 and the FG signal 32 as input signals. The preceding beam returning light amount 31 is the returning light amount by the spot 47 by the laser beam LB11 shown in FIG. 4 or the spot train 52 (hereinafter, the preceding beam) by the LB11 shown in FIG. The FG signal 32 is a fixed number of pulse trains per rotation synchronized with the rotation.

The preceding beam return light 31 calibrated by the signal calibrator 55 is input to the disturbance determiner A56, and is also filtered by the LPF 57 and then input to the disturbance determiner B58. The disturbance determination data generator 59 generates disturbance data based on the results of the disturbance determiner A56 and the disturbance determiner B58.

The generated disturbance determination data is the FG signal 3
2 together with the position data (address data) generated according to the timing control by the memory write timing control unit 60. The stored disturbance determination data is stored in the memory 63 before the recording position.
From the memory according to the timing control by the memory read timing controller 61, and the optical head protection controller 62
After the gain has been adjusted in step (1), the signal is output as an optical head protection voltage 36.

FIG. 8 shows the control voltage synthesizer 37 shown in FIG.
FIG. 3 is a diagram showing an internal structure of the device. The control voltage synthesis unit 37 includes:
The optical head protection voltage 36 and the focus control voltage 3
4 and an hold unit 67 for holding the focus control voltage 34 based on the total reflection return light amount 20. As described above, in the control voltage synthesizing unit 37, the optical head protection control voltage 36,
The focus control voltage 34 is input and the final focus control voltage 38 is output. At this time, the total reflection return light amount 2
0, it is determined whether or not the focus control voltage 34 is to be held, and the result and the optical head protection control voltage 36 are determined.
Is added by the adder 66 to become the final focus control voltage 38, which is applied to the optical head 15.

Hereinafter, the operation of protecting the SIL head in the optical recording apparatus shown in FIG. 1 will be described with reference to FIGS. First, a procedure for generating disturbance data inside the optical head protection device 35 will be described with reference to FIG. First,
In step S11, the preceding beam return light amount (hereinafter, referred to as
The disturbance detection signal) 31 is measured by the PD (3) 30. Next, in step S12, the disturbance detection signal 31 is standardized by the signal calibrating unit 55, and the standardized disturbance detection signal 64 is standardized.
Get. Here, as shown in FIG.
1 is a disturbance detection signal 64 calibrated to be 1 Vpp when no disturbance exists.

The next step S13 corresponds to the operation of the disturbance determination section A56 in FIG. 7, and compares the standardized disturbance detection signal 64 with a preset threshold T1. This threshold T1 is used to determine the presence or absence of a disturbance. If there is a convex defect such as dust on the glass master 16, the spot 47 of the preceding beam applied to the convex defect is scattered, and the disturbance detection signal 31 becomes smaller as compared with a case where there is no convex defect. . In the specific example shown in FIG. 10, the threshold value T1 is set to 0.3V.

If the disturbance detection signal 64 is larger than the threshold value T1, the disturbance determination unit A56 determines that "no disturbance exists" (step S14). If the disturbance detection signal 64 is smaller than the threshold value T1, the disturbance determination unit B58 determines that "there is a disturbance" (step S15).

If the disturbance judging section A56 judges "no disturbance" in step S14, no disturbance due to the convex defect is caused by the preceding beam, or even if the convex defect is present, the height of the disturbance is equal to that of the optical head 15. This is sufficiently lower than the gap with the glass master 16 and indicates that the disturbance is not a disturbance that makes the focus servo unstable. That is, this indicates that there is no possibility that the optical head 15 collides with the glass master 16. In this case, the optical head protection device 35 does not perform the optical head protection operation and performs only the focus control by the focus control device 33. Therefore, the disturbance determination data generation unit 59 does not perform the optical head protection operation as the disturbance determination data. Is generated (step S16).

On the other hand, when the disturbance determination unit A56 determines in step S15 that "disturbance exists", it is next determined whether or not the disturbance to the focus servo error due to the convex defect is within or outside the focus servo band ( Step S17)
Thereafter, the process proceeds to Steps S18 and S20 to determine the size (type) of the convex defect. The processes in steps S17, S18, and S20 are processes performed by the system of the LPF 57, the disturbance determination unit B58, and the disturbance determination data generation unit 59 in FIG. 7 as described below.

First, at step S17, the disturbance detection signal 64
Through the LPF 57 to remove frequency components outside the servo band. For this reason, the cutoff frequency of the LPF 57 is set to be substantially the same as the servo band. Then step 18
And 20, the disturbance detection signal 65 after passing through the LPF 57
Is compared with the threshold values T2 and T3 shown in FIG. FIG.
In the specific example shown in FIG. 1, T2 is set to 0.3 and T3 is set to 0.1, so that T3 <T2. Further, the threshold T2 and the threshold T3 can be set independently of the threshold T1.

If the disturbance detection signal 65 is larger than the dark value T2 in step S18, it is determined that the disturbance detection signal 65 is within the band of the LPF 57, that is, within the band of the focus servo. In this case, even if the disturbance determination unit A56 determines that there is "disturbance" (step S15), control is performed by the focus control device 33 so as to reduce the influence of the disturbance, since the optical head 15 is within the focus servo band. There is no possibility of collision with the glass master 16. In this case, the optical head protection device 3
5 does not perform the optical head protection operation, but performs only the focus control by the focus control device 33. Then, the disturbance determination data generator 59 generates disturbance determination data “00” indicating that the optical head protection operation is not performed (Step S19).

In step S18, the disturbance determination section B sets the LPF
If the subsequent disturbance detection signal 65 is determined to be equal to or smaller than the threshold value T2, the detected disturbance is determined to be outside the focus servo band. In this case, it is determined that the focus control device 33 cannot cope with the disturbance because the projection defect exists and is outside the focus servo band. In this state, the optical head 15 collides with the convex defect or the focus control becomes unstable due to disturbance due to the convex defect.
May collide with the glass master 16, damaging the optical head 15 and making recording impossible. Therefore, in this case, in order to prevent and protect the optical head 15 from being damaged, an optical head protecting operation by the optical head protecting device 35 is performed. As the optical head protection operation, for example, the optical head is caused to perform a jump operation at a convex defective portion, thereby preventing and protecting the optical head 15 from being damaged. Step S is performed to separate the jump operation, which is the optical head protection operation, according to the type of disturbance.
Perform 20.

That is, in step S20, the size (type) of the convex defect determined to be outside the focus servo band is further classified by the disturbance determining unit B58. In order to switch the jump operation as the optical head protection operation after the disturbance determination data generation unit 59 according to the classification result,
The magnitude of the protection control voltage of the optical head 15 is determined. FIG.
In the first embodiment, the disturbance determination unit B58 outputs the disturbance detection signal 65
By comparing the threshold value T3 with the threshold value T3, the size of the convex defect is classified into two types. When the disturbance detection signal 65 is larger than the threshold value T3, the convex defect itself is smaller than when the disturbance detection signal 65 is equal to or smaller than the threshold value T3. Therefore, the protection operation A in which the magnitude of the jump operation is shortened is performed. The generation unit 59 generates “10” indicating that the protection operation A is performed as the disturbance determination data (step S21).

On the other hand, if the disturbance detection signal 65 is smaller than the threshold T3, it is determined that the projection defect is larger than the projection defect when the disturbance detection signal 65 is larger than the threshold T3.
It is assumed that the protection operation B in which the size of the jump operation is lengthened is performed. In this case, the disturbance determination data generation unit 59
“0” indicating that the protection operation B is performed as the disturbance determination data
1 "is generated (step S22).

As described above, the disturbance determination data generation section 59 generates disturbance determination data for switching the protection operation according to the presence or absence of a convex defect and the size (type) of the convex defect. The position on the circumference where the disturbance is detected is determined by the FG signal 32 with a fixed number of pulses per rotation. Further, by counting the FG signal 32, the position in the radial direction is also specified.

The disturbance detection position information specified as described above and the generated disturbance determination data are synchronized by the memory write timing control unit 60 and stored in the memory 63.

FIG. 12 shows a recording start operation procedure. The disturbance determination data stored in the memory 63 is read by the memory read timing control unit 61 that operates independently of the write timing of the disturbance determination data.
In step S25, the disturbance determination data of at least the length section of the SIL diameter width is read into the read data cell prior to the recording location.

FIG. 13 shows a specific example of the position on the glass master 16 where the disturbance determination data is read and the read data cells. 13, a recording spot 46 is formed on the glass master 16 by the focus control device 33 shown in FIG.
Is formed. This condensing spot 46 is located on the SIL end face 4
5 is formed at the center position. The disturbance determination data includes a position (preceding read position) 67 preceding the recording spot position.
, At least the length section of the SIL diameter width is read. To read the disturbance determination data, the FG signal 32
And using a separate counter that operates independently of the write operation. The read disturbance determination data is temporarily stored in a read data cell. This read data cell can be realized by, for example, a D-flip flop. In the specific example shown in FIG. 13, n read cells are prepared.

Returning to FIG. 12, in step S26, it is checked whether or not all the n read data cells are disturbance determination data. At the preceding beam spot 47 in FIG. 4, disturbance detection is performed at one point. Therefore, when reading the detected disturbance determination data, it takes time until the disturbance determination data is reflected on all of the n read data cells. n
If the focus control is performed and the recording is started before the disturbance determination data is not reflected on all of the read data cells, the SIL end face 45 and the glass are caused by an unexpected disturbance due to insufficient reading of the disturbance determination data at the recording location. Master 1
There is a danger that 6 will collide.

In order to avoid this danger, if all of the n read data cells are not the disturbance determination data in step S26, the process returns to step S25, and focus control is not started. Only collect. At this time, the preceding beam spot 4
7 is realized by the low NA condenser lens 40,
It is possible to hold the optical head at a distance such that the optical head does not collide with the convex defect on the glass master 16 and collect disturbance data independently of the focus control.

On the other hand, if it is determined in step S26 that all of the n read data cells are disturbance determination data, focus control is started in step S27. Thereafter, the disturbance detection and the focus control by the preceding beam sbot 47 are performed in parallel.

The preceding beam spot array 5 shown in FIG.
In the disturbance detection by No. 2, prior to the recording spot 46,
N disturbance determination data is obtained in real time. Therefore, in this method, it is not necessary to store the disturbance determination data in the memory 63, and the recording start processing shown in FIG. In the disturbance detection methods shown in FIGS. 4 and 5, at least the SIL at the position preceding the recording spot 46 is used.
It is only necessary to obtain the disturbance data of the length section of the diameter width, and the disturbance determination data of the entire glass master 16 is unnecessary.

FIG. 14 shows a protection operation process based on disturbance determination data. The disturbance determination data stored in the read data cell indicates the disturbance determination data in a section of the SIL diameter width or more that covers the glass master 16 by recording. The optical head protection processing by the optical head protection device 35 is determined based on the disturbance determination data stored in the read data cell.

In step S30 of FIG. 14, all of the n pieces of disturbance determination data stored in the read data cell are set to "0".
It is checked whether it is "0". If all are “00”, the foreign matter having a convex shape is formed in the section exceeding the width of the SIL that covers the glass master 16 by recording.
This indicates that there is no possibility that the focus control becomes unstable due to a collision with the end face or a disturbance and the SIL collides.
In this case, the optical head protection device 35 does not perform the optical head protection process (step S31), and the optical head protection control voltage 36 is set to zero output.

If it is determined in step S30 that the n pieces of disturbance determination data stored in the read data cell are not all "00", then in step S32, the n pieces of disturbance determination data stored in the read data cell are determined. It is checked whether "01" is included in the data. If "01"
Is included, a disturbance having a size that requires the protection operation B exists in at least one section in a section that is equal to or larger than the SIL diameter width that covers the glass master 16 by recording. Therefore, in this case, the optical head protection device 35 needs to perform the protection operation B as the optical head protection processing.
Is output (step S33). In the above case, even when the disturbance determination data stored in the read data cell includes “10”, that is, when there is a disturbance for which the protection operation A needs to be performed, the protection operation B can cope with the disturbance. Therefore, it is possible to protect the optical head without any problem.

If it is determined in step S 31 that “01” is not included in the n pieces of disturbance determination data stored in the read data cell, all of the detected disturbances can be dealt with by the protection operation A. It is a disturbance of magnitude. Therefore, in this case, the optical head protection device 35 performs the protection operation A as the optical head protection processing, and the optical head protection control voltage 3
As 6, the voltage for performing the protection operation A is output (step S34).

Next, the operation of the control voltage synthesizer 37 in FIG. 1 will be described with reference to FIGS. FIG. 15 is a flowchart illustrating a processing procedure of the control voltage synthesis unit 37. FIG. 16 is a time change characteristic diagram of the total reflection return light amount 20 after calibration controlled by the focus control device 33. Note that, in addition to the defect such as the above-described convex defect, a defect such as a concave defect such as a scratch is also considered.

In step S40, the total reflection returning light amount 20 is compared with a threshold value T4 shown in FIG. In the specific example of FIG. 16, the focus control target value 69 is 0.6,
4 is set to 0.8. Note that the threshold value T4 is the same as that in FIG.
The threshold value T1 shown in FIG. 11 and the threshold value T2 shown in FIG.
And T3 are set independently.

The focus controlled voltage 68 is constant at 0.6 by the focus control target value 69 by the focus control device 33. However, when there is a concave defect such as a scratch on the glass master 16 or when the optical head protection operation described above functions, the focus controlled voltage 68 fluctuates above 0.6. In this case, if the total reflection return light amount 20 becomes larger than the threshold value T4, only the focus control voltage 34 by the focus control device 33 is held in step S41 of FIG. 15 when the total reflection return light amount 20 exceeds the threshold value T4. It is held by the processing unit 67.

Next, in step S42, the focus control voltage 34 and the optical head protection control voltage 36 are added to each other by the adder 66 to obtain a final focus control voltage 38. The final focus control voltage 38 is fed back to the optical head 15. As described above, even when there is a defect on the glass master 16 and disturbance occurs, by always operating the focus servo loop by the focus control device 33, the focus pull-in characteristic when disturbance is applied due to the defect becomes faster. In addition, it is possible to avoid the risk that the SIL end face 45 and the glass master 16 collide with each other due to the focus control excessively following disturbance caused by a concave defect such as a scratch.

With the above operation, even when disturbance due to a defect due to a convex defect such as dust or a concave defect such as a scratch is applied to the surface of the glass master 16 to the focus servo, the focus servo does not follow the light. Head 15
Collision due to the concave defect of the above and the damage of the glass master 16 with resist caused thereby can be avoided, and cutting for a long time can be stably performed.

The optical recording apparatus shown in FIG. 1 has been described above. Next, a specific example of the optical reproducing apparatus of the optical recording and / or reproducing apparatus of the present invention will be described.
In this specific example, the optical reproducing method among the optical recording and / or reproducing methods of the present invention can be applied.

A specific example of the optical reproducing apparatus is shown in FIG. 1 for reproducing information recorded on an optical disk by irradiating a laser beam.
7 is an optical reproducing apparatus shown in FIG.

The configuration of the main part of the optical reproducing apparatus will be described. This optical reproducing apparatus includes a laser element 4 (laser 1) for emitting a reproducing laser beam for reproducing an information signal from an optical disk 70, and a laser beam for reproducing from the laser element 4 for irradiating the optical disk 70 with the reproducing laser beam. The aspheric lens 43 inside the optical head 15 for condensing light, and the inside of the optical head 15 interposed between the aspheric lens 43 and the optical disc 70 in order to realize a numerical aperture larger than the numerical aperture of the aspheric lens 43. A laser element (laser 2) 21 for emitting a laser beam for disturbance detection different from the reproduction laser beam to the optical disk 70, and a near-field area between the end surface 45 of the SIL 44 and the optical disk 70. And the SIL 44 for focusing the laser beam for reproduction by the focus control device 33 for maintaining the distance at An optical head protection device 35 that protects the SIL 44 and the glass master 16 based on the return light from the optical disk 70 by the laser light from the laser element 21 focused on the position preceding the position is provided as a main part.

Further, this optical reproducing apparatus sets the optical head protection control voltage 36 of the optical head protection device 35 and the focus control voltage 34 of the focus control device 33 on the basis of the amount of the laser beam for reproduction returned from the SIL 44. A control voltage synthesizing unit 37 for synthesizing the output or outputting it alone is also provided as a main part.

Next, the overall configuration of the optical reproducing apparatus shown in FIG. 17 will be described while clarifying the relationship between the main part and its peripheral parts. The reproduction laser beam LB1 emitted from the laser element 4 (laser 1) is converted into an electro-optical conversion element (EO).
M) 5, after being reflected by the mirror 10 via the analyzer 6 as a polarizing plate and the beam splitter (BS) 7,
After passing through the condenser lens 55, the beam is converted into a parallel beam by the collimator lens 11, and the polarized beam splitter (PB)
S) passes through 12 and is incident on the λ / 4 plate 13.

The modulated light LB3 that has passed through the λ / 4 plate 13 is
The light becomes circularly polarized light and is input to the dichroic mirror 14.
The dichroic mirror 14 has a wavelength of LB3.
It has the property of transmitting light.

The laser beam LB 4 transmitted through the dichroic mirror 14 is reflected by the mirror 10 and then reflected by the optical head 1.
5 is incident. This optical head 15 is
Irradiate the circularly polarized laser light in the form of a spot. At this time, the focus of the optical head 15 on the optical disk 70 is controlled by the focus control device 33,
The gap with the glass master 16 is kept constant.

The laser beam LB4 incident on the optical head 15
The light spot is formed on the optical disk 70 with the size being controlled to be constant by the focus control device 33. An information signal is read from the optical disk 70 by the light spot and reproduced.

A part LB8 of the reproducing laser beam from the laser element 4 passes through the EOM 5 and the analyzer 6 and passes through the BS
7, and is detected by the photodetector (PD1) 8. The laser beam LB8 incident on the PD (1) 8 is converted into an electric signal, input to an automatic power controller (APC) 9, and the value is fed back to the EOM 5, whereby the power of the laser element 4 is controlled to be constant. Therefore, AP
The light amount after C is a constant amount, and becomes the maximum light amount 19.

On the other hand, the return light from the optical head 15 for the laser light LB4 transmitted through the dichroic mirror 14 is:
After passing through the dichroic mirror 14 again and being converted into linearly polarized light through the λ / 4 plate 13, it is reflected by the PBS 12,
Further, a part is a beam splitter (BS) 71, a mirror 1
After being reflected at 0 g, the light is condensed by a condenser lens 72 and input to a photodetector (PD5) 73. The detection signal detected by the photodetector (PD5) 73 is supplied to a reproducing unit 74, where the signal is subjected to reproduction signal processing, and an output terminal 75
A reproduction signal can be obtained from.

Further, the light is transmitted through the BS 71 and
Return light LB5 collected by the photo detector (PD)
2) Input to 18 and detected as return light quantity 20.

The disturbance detecting laser light emitted from the laser element (laser 2) 21 passes through the same path as that of the optical recording system, is reflected by the beam splitter (BS) 24, and becomes a laser light LB6. After being bent by the mirror 10d, the light enters the condenser lens 54. Condensing lens 5
4 focuses the laser beam LB6 and then enters the collimator lens 27.

Since the laser beam LB6, which has been converted into parallel light by the collimator lens 27, becomes a laser beam LB11 and is irradiated onto the optical disk 70 via the optical head 15, the operation is substantially the same as the operation of the above-described optical recording apparatus. Then, the description is omitted. Of course, the irradiation position on the optical disk 70 by the laser beam LB11 is the same as the laser beam L
It is different from the irradiation position by B4.

The return light from the optical head 15 to the laser light LB11 is also input to the photodetector (PD3) 30 along the same path as that of the above-described optical recording apparatus, and is set as the leading beam return light amount 31 to protect the optical head. Input to the device 35.

As in the case of the above-described optical recording apparatus, the optical head protection device 35 includes, in addition to the preceding beam return light amount 31,
A rotation-synchronized FG signal 32, which is a fixed number of pulse trains per rotation, is input. The FG signal 32 specifies the detection position of the preceding beam return light amount 31 on the glass master 16. The disturbance detection result based on the preceding beam return light amount 31 and its position signal are stored in the optical head protection device 35 prior to recording. Stored in memory.

The control voltage synthesizing section 37 reads out the disturbance detection result stored in the memory in the optical head protection device 35 prior to the recording position, and focuses on the basis of the read value so as to eliminate the influence of the disturbance. The control voltage 34 is corrected, and the final focus control voltage 38 is output. The optical head 15 receiving the final focus control voltage 38
Means that even if there is a defect on the optical disc 70,
Reproduction can be performed stably for a long time without colliding with the optical disk 70 due to disturbance.

Hereinafter, the detailed structure of the optical head 15 will be described first.
The operation and processing of each unit are the same as those of the above-described optical recording apparatus, and thus the description is omitted.

In this optical reproducing apparatus, the optical disk 7
The focus servo does not follow even if disturbance due to a defect due to a convex defect such as dust or a concave defect such as a scratch is applied to the surface of the optical head 15, and the collision due to the concave defect of the optical head 15. The accompanying damage of the optical disk 70 can be avoided, and stable long-time reproduction can be performed.

[0104]

According to the present invention, there is provided an optical recording and / or reproducing apparatus for recording and / or reproducing information signals at a high density by bringing an objective lens having a high numerical aperture close to an optical recording medium surface.
By making it possible to prevent the objective lens from colliding with a defect or the like on the optical recording medium, it becomes possible to record and / or reproduce information without wearing or damaging the objective lens and the optical recording medium.

Further, in a cutting machine used for manufacturing CDs and DVDs, information can be recorded stably for a long time using near-field light, and a high-density optical disk can be manufactured.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical recording apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an optical head constituting the optical recording apparatus.

FIG. 3 is a characteristic diagram illustrating a relationship between a distance between an optical recording medium and an SIL end surface and a return light amount.

FIG. 4 is a diagram showing a position of a preceding beam in an optical recording medium in the optical head.

FIG. 5 is a diagram showing a position of a preceding beam spot train in the optical head on an optical recording medium.

FIG. 6 is a diagram showing an optical system for realizing the preceding beam spot array shown in FIG. 5;

FIG. 7 is a block diagram showing a configuration of an optical head protection device using the preceding beam shown in FIG. 5;

FIG. 8 is a block diagram of a control voltage synthesis unit that synthesizes a control voltage and a focus control voltage by the optical head protection device.

FIG. 9 is a flowchart showing a procedure for generating disturbance data in the optical head protection device.

FIG. 10 is a diagram showing a disturbance detection signal after calibration when a convex defect exists in a glass master.

FIG. 11 is a diagram showing a disturbance detection signal after a low-pass filter when a convex defect exists in a glass master.

FIG. 12 is a flowchart showing a recording start process in the optical head protection device.

FIG. 13 is a diagram showing a position where disturbance data is read in the optical head protection operation processing.

FIG. 14 is a flowchart showing a procedure of an optical head protection operation process in the optical head protection device.

FIG. 15 is a flowchart showing a procedure for synthesizing a control voltage and a focus control voltage by the head protection device.

FIG. 16 is a diagram illustrating a state of total reflection returning light amount when a convex defect exists in a glass master.

FIG. 17 is a block diagram of an optical reproducing apparatus according to another embodiment of the present invention.

[Explanation of symbols]

4 laser element, 15 optical head, 16 glass master, 19 maximum recording light quantity, 20 total reflection return light quantity, 33
Focus control device, 32 FG signal, 34 focus control voltage, 35 optical head protection device, 36 optical head protection control voltage, 37 control voltage synthesizer, 38 final focus control voltage, 42 piezo element, 43 aspheric lens, 44 solid immersion Lens, 56 disturbance determination unit A, 58
Disturbance judgment unit B, 59 disturbance judgment data generation unit, 60 memory write timing control unit, 61 memory read timing unit, 63 memory

Claims (37)

[Claims] A first light source for emitting recording / reproducing light for recording / reproducing an information signal on / from an optical recording medium; and a recording / reproducing light from the first light source being transmitted to the optical recording medium. First optical means for converging light for irradiation, and a second optical means interposed between the first optical means and the optical recording medium for realizing a numerical aperture larger than the numerical aperture of the first optical means. A second light source that emits light different from the recording / reproducing light to the optical recording medium; and a near-field area between the end face of the second optical means and the optical recording medium. Control means for keeping the distance constant; and light from the second light source focused on a position preceding the position on the optical recording medium on which the second optical means condenses the recording / reproducing light. Based on the return light of the optical recording medium, The optical recording and / or reproducing apparatus, characterized in that it comprises a protection means for protecting the climate recording medium. 2. The optical recording and / or reproducing apparatus according to claim 1, wherein a protection control signal output by said protection means and a focus control signal output by said control means are switched or used together. 3. A protection control signal output by the protection means is synthesized with a focus control signal output by the control means based on a return light amount of the recording / reproducing light from the second optical means and output. 3. The optical recording and / or reproducing apparatus according to claim 2, further comprising control voltage output means for outputting the output signal independently or by itself. 4. The method according to claim 1, wherein the protection unit compares a return light amount of the preceding light condensed on the optical recording medium with a first predetermined threshold value to determine whether there is a disturbance on the optical recording medium. 1 determination means, and second determination means for determining the type of disturbance by comparing the amount of return light of the preceding light in the focus control band with at least a second predetermined threshold value, based on both determination results. 2. The optical recording and / or reproducing apparatus according to claim 1, wherein the second optical means and the optical recording medium are protected from disturbance according to the judgment data. 5. The method according to claim 1, wherein the second determining unit is configured to set a return light amount of the preceding light in the focus control band to a second predetermined threshold value and a third predetermined threshold value set to be smaller than the second predetermined threshold value. 5. The optical recording and / or reproducing apparatus according to claim 4, wherein the type of the disturbance is determined by comparing with a threshold value. 6. The control voltage output means controls the protection control signal based on a result of comparing a return light amount of the recording / reproducing light from the second optical means with a fourth predetermined threshold value. 4. The optical recording and / or reproducing apparatus according to claim 3, wherein it is determined whether to combine with the signal or to output the signal alone. 7. The control voltage output means, when the return light amount of the recording / reproducing light from the second optical means becomes larger than the fourth predetermined threshold while the control means is operating. 7. The optical recording and / or reproducing apparatus according to claim 6, wherein the focus control signal of the control unit is held, and only the protection control signal of the protection unit is output. 8. The focus control signal, wherein the first optical means and the second optical means are integrated, and the control means outputs the position of the integrated optical means in the focus direction on the optical recording medium. The optical recording and / or reproducing apparatus according to claim 1, wherein the optical recording and / or reproducing apparatus is controlled by switching or using a protection control signal output from the protection means. 9. A protection control signal output by the protection means is synthesized with a focus control signal output by the control means based on a return light amount of the recording / reproducing light from the second optical means and output. 9. The optical recording and / or reproducing apparatus according to claim 8, further comprising control voltage output means for outputting the voltage information independently or independently. 10. The optical recording and / or reproducing apparatus according to claim 9, wherein said integrated optical means jumps over a disturbance generating section on said optical recording medium based on an output of said control voltage output means. . 11. The preceding light from the second light source,
The light having a wavelength that does not record an information signal on the optical recording medium,
11. The optical recording and / or reproducing apparatus according to claim 10, wherein the light is condensed on the optical recording medium even when the integrated optical means jumps over a disturbance generating portion on the optical recording medium. . 12. The first determination means and the second determination means of the protection means compare the return light amount of the preceding light with the first predetermined threshold value and the second predetermined threshold value. Is an unrecorded portion in front of a location on the optical recording medium to which the second optical means is irradiating the recording / reproducing light, and at least the second optical means is the recording / reproducing light. 5. The optical recording and / or reproducing apparatus according to claim 4, wherein a section having a width having a width of said second optical means with a center of a light condensing point as a center. 13. The position at which the information signal is recorded / reproduced on / from the optical recording medium, and the presence / absence and type of the disturbance are determined by the protection means using the first determination means and the second determination means. The optical recording and / or reproducing apparatus according to claim 4, wherein the determination positions are separated. 14. The recording apparatus according to claim 1, wherein before recording / reproducing the information signal on / from the recording medium, the protection means determines in advance whether or not there is disturbance on the recording medium. Optical recording and / or reproducing apparatus. 15. Before recording / reproducing an information signal on / from the recording medium, information on the disturbance determined in advance by the protection means is stored in a storage element in advance, and the information is stored in the optical recording medium. At the time of recording / reproducing an information signal by reading out the disturbance information from the storage element, the protection means protecting the end face of the second optical means and the optical recording medium based on the read disturbance information. The optical recording and / or reproducing apparatus according to claim 14, wherein: 16. In an initial state in which an information signal is recorded / reproduced on / from the optical recording medium, the second optical means is used until the center of the second optical means reaches a recording / reproduction start radius. 2. The optical recording and / or reproducing apparatus according to claim 1, wherein the distance between the end face of the optical recording medium and the optical recording medium is not kept constant in the near field area. 17. An apparatus according to claim 17, wherein in an initial state of recording / reproducing an information signal on / from said optical recording medium, focus control by said control means is not performed until said disturbance information is accumulated in said storage element. 16. The optical recording and / or reproducing apparatus according to 15. 18. The method according to claim 18, wherein before the information signal is recorded / reproduced on / from the recording medium, the protection means detects the disturbance information on the optical recording medium in advance. 2. The optical recording apparatus according to claim 1, wherein in an initial state in which recording is started, the recording is performed until the center of the second optical unit reaches a recording / reproduction start radius and thereafter, the recording is stopped. And / or a playback device. 19. An information signal is recorded / recorded on an optical recording medium.
The first optical means for realizing a numerical aperture larger than the numerical aperture of the first optical means for converging the recording / reproducing light from the first light source for reproduction onto the optical recording medium so as to irradiate the optical recording medium. An end face of a second optical means interposed between the optical recording medium and the optical recording medium; a control step of maintaining a constant distance in the near field area between the optical recording media; and a light different from the recording / reproducing light. And a protection step of protecting the second optical unit and the optical recording medium from disturbance information obtained by irradiating a disturbance generator on the optical recording medium with light from a second light source that emits light. An optical recording and / or reproducing method characterized by the above-mentioned. 20. The light from the second light source, wherein the light from the second light source is
20. The optical recording and / or reproducing method according to claim 19, wherein the optical means is focused at a position preceding the position at which the recording / reproducing light is focused. 21. The optical recording and / or reproducing method according to claim 19, wherein a protection control signal output by the protection step and a focus control signal output by the control step are switched or used in combination. 22. A protection control signal output by the protection step is synthesized with a focus control signal output by the control step based on a return light amount of the recording / reproduction light from the second optical means, and output. 22. The optical recording and / or reproducing method according to claim 21, further comprising a control voltage output step of outputting the control voltage independently or by itself. 23. The protection step, wherein the amount of return light of the preceding light condensed on the optical recording medium from the optical recording medium is compared with a first predetermined threshold value, and disturbance on the optical recording medium is performed. A first determination step of determining the presence / absence of, and a second determination step of comparing the amount of return light of the preceding light in the focus control band with at least a second predetermined threshold to determine the type of the disturbance, 20. The optical recording and / or reproducing method according to claim 19, wherein the second optical means and the optical recording medium are protected from disturbance according to judgment data based on both judgment results. 24. The method according to claim 24, further comprising the step of: setting a return light amount of the preceding light in the focus control band to a second predetermined threshold value and a third predetermined threshold value set to be smaller than the second predetermined threshold value. 24. The optical recording and / or reproducing method according to claim 23, wherein the type of the disturbance is determined by comparing with a threshold value. 25. The control voltage outputting step, wherein the recording /
Determining whether to synthesize the protection control signal with the focus control signal or to output the protection control signal alone based on a result of comparing a return light amount of the reproduction light from the second optical unit with a fourth predetermined threshold value. The optical recording and / or reproducing method according to claim 22, characterized in that: 26. The recording / recording apparatus according to claim 17, wherein the control step is in operation.
The amount of reproduction light returned from the second optical means is equal to the fourth light amount.
26. The control voltage output step holds the focus control signal of the control step and outputs only the protection control signal of the protection step when the threshold voltage becomes larger than a predetermined threshold value. Optical recording and / or reproducing method. 27. The focus control signal, wherein the first optical means and the second optical means are integrated, and the control step outputs the position of the integrated optical means in the focus direction on the optical recording medium. 20. The optical recording and / or reproducing method according to claim 19, wherein the control is performed by switching or using a protection control signal output from the protection step. 28. A protection control signal output by the protection step is synthesized with a focus control signal output by the control step based on a return light amount of the recording / reproducing light from the second optical means, and output. 28. The optical recording and / or reproducing method according to claim 27, further comprising a control voltage output step of outputting the control voltage independently or by itself. 29. The optical recording and / or reproducing method according to claim 28, wherein the integrated optical means jumps over a disturbance generating portion on the optical recording medium based on the output of the control voltage output step. . 30. The preceding light from the second light source,
The light having a wavelength that does not record an information signal on the optical recording medium,
30. The optical recording and / or reproducing method according to claim 29, wherein light is condensed on the optical recording medium even when the integrated optical means jumps over a disturbance generating portion on the optical recording medium. . 31. The first determination step and the second determination step of the protection step, wherein the returning light amount of the preceding light is compared with the first predetermined threshold value and the second predetermined threshold value. Is an unrecorded portion in front of a location on the optical recording medium to which the second optical means is irradiating the recording / reproducing light, and at least the second optical means is the recording / reproducing light. 24. The optical recording and / or reproducing method according to claim 23, wherein the optical recording and / or reproducing method is a section having a length having a width of the second optical means centering on a portion where light is converged. 32. A position at which the information signal is recorded / reproduced on / from the optical recording medium, and the presence / absence and type of the disturbance are determined by the protection step using the first determination step and the second determination step. The optical recording and / or reproducing method according to claim 23, wherein the determination positions are separated. 33. The recording medium according to claim 19, wherein before recording / reproducing the information signal on / from the recording medium, the protection step first determines the presence / absence and type of disturbance on the recording medium. Optical recording and / or reproducing method. 34. Before recording / reproducing an information signal on / from the recording medium, information on the disturbance determined in advance in the protection step is stored in a storage element in advance, and the information is stored in the optical recording medium. At the time of recording / reproducing an information signal by reading the disturbance information from the storage element, and the protection step protects the end face of the second optical means and the optical recording medium based on the read disturbance information. 34. The optical recording and / or reproducing method according to claim 33, wherein: 35. In an initial state in which an information signal is recorded / reproduced on / from the optical recording medium, the second optical means is used until the center of the second optical means reaches a recording / reproduction start radius. 20. The optical recording and / or reproducing method according to claim 19, wherein the distance between the end face of the optical recording medium and the optical recording medium is not kept constant in the near field area. 36. In an initial state in which an information signal is recorded / reproduced on / from the optical recording medium, focus control by the control step is not performed until the disturbance information is accumulated in the storage element. 35. The optical recording and / or reproducing method according to claim 34. 37. Before recording / reproducing an information signal on / from the recording medium, the protection step detects the information of disturbance on the optical recording medium in advance by detecting the information signal on the optical recording medium. 20. The optical recording according to claim 19, wherein in an initial state in which recording is started, the recording is performed until the center of the second optical means reaches a recording / reproduction start radius and thereafter, the recording is stopped. And / or playback method.