JP2002184014A - Optical device for information recording/reproducing, information-recording medium and information recording /reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent scratching or damaging on a light transmission part of a convex spherical lens or the surface of an information recording medium, even if the information-recording medium collides with the convex spherical lens, arranged adjacent to the information recording medium of an optical pickup device. SOLUTION: The surface at the side of the information-recording medium 1 of the convex spherical lens of the optical pickup device 6, converging to the information recording medium 1 though an objective lens 15 and the convex spherical lens 16 is formed with the curved surface. The convex spherical lens 16 is arranged, by keeping the minute space, with respect to the information recording medium 1, and then the omission of a part of or the whole convex spherical lens 16, or the scratch on the surface of the convex spherical lens 16 and the surface of the information recording medium 1 is prevented, even when the information recording medium 1 is brought into contact with the convex spherical lens 16, when the information is being recorded or reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to an information recording / reproducing optical device, an information recording medium, and an information recording / reproducing device for writing information on an optical recording medium and reading information from the optical recording medium on which information is recorded.

[0002]

2. Description of the Related Art An optical pickup device used for recording and reproducing information on and from an information recording medium such as an optical disk has a light diffraction limit determined by the numerical aperture of an objective lens and the wavelength of light.
The spot size for recording and reproducing is limited to about the wavelength of light. In order to realize a high numerical aperture of this objective lens, for example, JP-A-5-189796 and JP-A-10-12
As disclosed in JP-A-3410 and JP-A-11-3534, a convex spherical lens is inserted between an objective lens and an information recording medium in the same manner as in the liquid immersion method of a microscope, and the convex spherical lens is brought close to the information recording medium. Thus, the effective numerical aperture is increased by an amount corresponding to the refractive index of the convex spherical lens. And JP 10-12
As disclosed in Japanese Patent No. 3410, the distance between the convex spherical lens and the information recording medium is several tens μm or more, which is a value larger than the wavelength of light, due to problems such as dust and dust and the problem of the removable property of the information recording medium. And

[0003]

When information is recorded on or reproduced from an information recording medium by the optical pickup device, focus control is performed between the convex spherical lens and the information recording medium. However, the information recording medium itself may be tilted with respect to the surface of the convex spherical lens due to mechanical characteristics of the information recording medium or deviation of a shaft rotating the information recording medium. Also, when the effective numerical aperture is increased by using a convex spherical lens to make the distance between the convex spherical lens and the information recording medium extremely narrow, if the information recording medium is tilted, the information recording medium becomes convex during rotation. May collide with spherical lenses. In addition, when the information recording medium is not rotating, the convex spherical lens may collide with the information recording medium due to an external impact or the like. When the information recording medium collides with the convex spherical lens in this way, the surface of the convex spherical lens or the information recording medium is scratched, a part of the convex spherical lens is chipped, and in the worst case, the convex spherical lens is broken. Sometimes.

The present invention has been made to solve the above-mentioned disadvantages, and prevents a collision between a convex spherical lens provided in close proximity to an information recording medium and an information recording medium. An object of the present invention is to provide an information recording / reproducing optical device, an information recording medium, and an information recording / reproducing device that prevent a portion of a lens through which light passes or a surface of an information recording medium from being scratched or damaged.

[0005]

The information recording / reproducing optical device according to the present invention is an information recording / reproducing optical device for condensing a light beam emitted from a light source onto an information recording medium through an objective lens and a convex spherical lens. The surface of the convex spherical lens on the side of the information recording medium is formed as a curved surface, and the convex spherical lens is arranged at a minute interval from the information recording medium.

A second information recording / reproducing optical device according to the present invention is an information recording / reproducing optical device for condensing a light beam emitted from a light source onto an information recording medium through an objective lens and a convex spherical lens. Having an optical element in which a convex spherical lens is integrally disposed on a transparent substrate, forming a surface of the optical element on the information recording medium side having the convex spherical lens with a curved surface,
The surface of the optical element on the side of the convex spherical lens is arranged at a small distance from the information recording medium.

A third information recording / reproducing optical device according to the present invention is an information recording / reproducing optical device for condensing a light beam emitted from a light source on an information recording medium through an objective lens and a convex spherical lens. The optical element has a convex spherical lens integrally disposed on a transparent substrate. The optical element has a curved surface around the information recording medium side having the convex spherical lens, and the optical element has a convex spherical lens side surface. Are arranged at a minute interval with respect to the information recording medium.
It is preferable that the radius of curvature of the curved surface at the peripheral portion of the optical element be asymmetrically different from the optical axes of the objective lens and the convex spherical lens.

A fourth information recording / reproducing optical device according to the present invention is an information recording / reproducing optical device for condensing a light beam emitted from a light source on an information recording medium through an objective lens and a convex spherical lens. An optical element having a convex spherical lens integrally disposed on a transparent substrate; a buffer having a fixed height provided in a region other than the convex spherical lens on the information recording medium side having the convex spherical lens of the optical element; Is characterized in that the surface on the side of the convex spherical lens is disposed at a minute interval from the information recording medium. Also, it is desirable to provide a protruding microstructure on the surface of the buffer.

An information recording medium according to the present invention is characterized in that a light-transmitting lubricant layer is formed on the surface of the information recording / reproducing optical device side.

[0010] An information recording / reproducing apparatus according to the present invention includes the above-mentioned information recording / reproducing optical device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disc apparatus for recording information on an information recording medium such as an optical disc and reading information recorded on the information recording medium according to the present invention is an optical pickup device mounted on an information recording medium mounted on a turntable. The information is recorded by irradiating a laser beam from the device, or the information recorded on the information recording medium is read.

The optical pickup device has a semiconductor laser element (hereinafter, referred to as an LD), a collimator lens, a polarizing beam splitter, a quarter-wave plate, an objective lens, a convex spherical lens, a condenser lens, and a light receiving element. The convex spherical lens is disposed between the objective lens and the information recording medium, and the convex spherical lens is disposed at a small distance from the information recording medium. In this convex spherical lens, the objective lens side is formed of a spherical surface having a small radius of curvature, and the information recording medium side is formed of a spherical surface having a large radius of curvature.

In this optical pickup device, the laser light emitted from the LD is converted into parallel light by a collimator lens, and changes from linearly polarized light to circularly polarized light through an optical isolator composed of a polarizing beam splitter and a quarter-wave plate. The light is condensed through the objective lens and the convex spherical lens and is incident on the information recording medium. The laser beam incident on the information recording medium is reflected by the information recording medium, passes through a convex spherical lens, an objective lens, and a quarter-wave plate, is reflected by a polarizing beam splitter, and is condensed on a light receiving element by a condensing lens. The information on the recording medium is reproduced. When recording or reproducing information with this optical pickup device, even if the information recording medium comes into contact with the information recording medium due to surface runout or the like, the information recording medium side of the convex spherical lens may be loose. Since it is formed with a spherical surface, it has little effect when it comes into contact with the information recording medium, and it can prevent part or all of the convex spherical lens from being chipped or scratching the surface of the convex spherical lens or the surface of the information recording medium. prevent.

[0014]

[Embodiment 1] FIG. 1 is a configuration diagram of an embodiment of the present invention. As shown in the figure, an optical disk device that records information on an information recording medium 1 such as an optical disk or reads information recorded on the information recording medium 1 includes a recognition information conversion unit 2 such as a personal computer, a control unit 3, Turntable 4,
It has a rotation motor 5 for rotating the turntable 4, an optical pickup device 6, and a feed motor 7 for moving the optical pickup device 6. The control unit 3 controls the driving of the rotation motor 5 and the feed motor 7 in accordance with the recognition information output from the recognition information conversion unit 2, and the laser beam from the optical pickup device 6 to the information recording medium 1 placed on the turntable 4. To record information or read information recorded on the information recording medium 1.

The information recording medium 1 has a protective layer / dielectric layer / recording layer / dielectric layer / reflective layer / substrate from the laser beam 19 incident side. However, the layer configuration of the information recording medium 1 is not limited to this. As the recording layer, a phase change material or a magneto-optical material is used. If the information recording medium 1 is read-only, there is a layer in which information is recorded in advance, and a guide groove for recording and reproducing information is provided.

The optical pickup device 6 has a semiconductor laser device (hereinafter referred to as LD) 1 as shown in the configuration diagram of FIG.
1, a collimator lens 12, and a polarizing beam splitter 13
, Quarter-wave plate 14, objective lens 15, and convex spherical lens 1
6 and a condenser lens 17 and a light receiving element 18. The convex spherical lens 16 is disposed between the objective lens 15 and the information recording medium 1, and the convex spherical lens 16 is positioned between the objective lens 15 and the information recording medium 1.
They are arranged at intervals of about 1 mm. As shown in FIG. 3, the convex spherical lens 16 has a spherical surface with a small radius of curvature on the objective lens 15 side, and a spherical surface with a large radius of curvature instead of a flat surface on the information recording medium 1 side. An anti-reflection film may be formed on the surface of the objective lens 15 or the surface of the convex spherical lens 16.

In the optical pickup device 6, the LD
Laser light 19 emitted from 11 is converted into collimated light by a collimator lens 12, passes through an optical isolator composed of a polarizing beam splitter 13 and a quarter-wave plate 14, and changes from linearly polarized light to circularly polarized light. The light is condensed through the convex spherical lens 16 and enters the information recording medium 1. The laser light 19 incident on the information recording medium 1 is reflected by the information recording medium 1. When the light is reflected, the turning direction of the circularly polarized light changes, passes through the convex spherical lens 16 and the objective lens 15, enters the quarter-wave plate 14, and when passing through the quarter-wave plate 14, is perpendicular to the paper surface. Light which is reflected by the polarization beam splitter 13 and condensed by the condensing lens 17.
And the information on the information recording medium 1 is reproduced. As described above, when the information on the information recording medium 1 is reproduced or recorded by the optical pickup device 6, the spot focused by the objective lens 15 and the convex spherical lens 16 is formed on the information recording medium 1 in the best condition. As described above, the optical pickup device 6 is mounted on the actuator and moves up and down so as to always keep a constant distance from the information recording medium 1.

When information is recorded or reproduced by the optical pickup device 6, the information recording medium 1
During this rotation, surface runout, eccentricity, warpage, etc. occur due to the mechanical characteristics of the substrate of the information recording medium 1. If the amount of the surface runout or warpage is large and the acceleration exceeding the movable range of the actuator or changing rapidly cannot follow, the convex spherical lens 16 and the information recording medium 1 come into contact. In addition, even when there is an external impact, the convex spherical lens 16 and the information recording medium 1 come into contact. Even if the convex spherical lens 16 and the information recording medium 1 come into contact in this manner, the influence of the convex spherical lens 16 on the information recording medium 1 being in contact with the information recording medium 1 is small because the information recording medium 1 side is formed with a gentle spherical surface. It is possible to avoid that a part or all of the convex spherical lens 16 is chipped or that the surface of the convex spherical lens 16 or the surface of the information recording medium 1 is damaged.

[Embodiment 2] In the above embodiment, the case where the objective lens 15 and the convex spherical lens 16 are provided separately has been described. However, as shown in FIG.
Has a refractive index n ₁ greater than the refractive index n ₀ of the substrate 20.
And a convex spherical lens 16 having a refractive index n ₂ greater than the refractive index n ₀ of the substrate 20 is embedded in the other surface of the transparent substrate 20.
The surface on the side of the 0 convex spherical lens 16 may be a gentle curved surface. Further, as shown in FIG. 4B, the objective lens is composed of two objective lenses 15a and 15b,
a, the objective lens 15a and the convex spherical lens 16 may be arranged on the transparent substrate 15b.
The substrate 20 on which the objective lens 15 and the convex spherical lens 16 are disposed, the substrate 20a on which the objective lens 15a is disposed, and the substrate 20 on which the objective lens 15b and the convex spherical lens 16 are disposed
b can be easily manufactured by using a microlens manufacturing technique using a photolithography technique and a dry etching technique. The distance between the substrate 20a and the information recording medium 1 is set such that the information recording medium 1 can be easily inserted into and removed from the optical disk device.

Also in this case, since the surface of the substrate 20 or the substrate 20b on the side of the information recording medium 1 on which the convex spherical lens 16 is arranged is formed with a gentle curved surface, the influence when the substrate 20 or the substrate 20b comes into contact with the information recording medium 1 is small. In addition, it is possible to avoid that part or all of the convex spherical lens 16 is missing or that the surface of the convex spherical lens 16 or the surface of the information recording medium 1 is damaged.

[Embodiment 3] In Embodiment 2, the case where the surface of the substrate 20 or the substrate 20b on the side of the information recording medium 1 on which the convex spherical lens 16 is arranged is formed as a gentle curved surface is shown in FIG. As described above, the portion of the convex spherical lens 16 on the side of the information recording medium 1 provided with the convex spherical lens 16 of the transparent substrate 20c on which the objective lens 15 and the convex spherical lens 16 are arranged is a plane, and the corner is a curved surface. Is also good. Also in the case of the third embodiment, even if the substrate 20c contacts the information recording medium 1, the corner of the surface of the substrate 20c on the information recording medium 1 side is formed as a curved surface, so that a part or all of the substrate 20c is formed. It can be avoided that the surface of the convex spherical lens 16 or the surface of the information recording medium 1 is damaged.

As shown in FIG. 6, the radius of curvature of the corner formed by the curved surface of the substrate 20c is asymmetric with respect to the optical axes of the objective lens 15 and the convex spherical lens.
May be increased, and the radius of curvature of the other corner 21b may be reduced. In this case, the information recording medium 1 is arranged such that a corner 21a having a large radius of curvature is located at a portion where the deflection is large, and a corner 21b having a small radius of curvature is located at a portion where the deflection of the information recording medium 1 is small. Deploy. That is, the corner 21a having a large radius of curvature with respect to the radial direction of the information recording medium 1 is arranged on the rotation axis side of the turntable 4 to which the information recording medium 1 is fixed, and the corner 21a having a large radius of curvature is arranged.
a is arranged on the outer peripheral side of the information recording medium 1. As described above, the corners 21a having a large radius of curvature are arranged so that the corners 21a having a large radius of curvature come to the portion where the deviation of the information recording medium 1 is large. By arranging, the substrate 20c is
Even when the substrate 20c contacts the information recording medium 1, the corner of the surface of the information recording medium 1 side is formed as a curved surface, so that part or all of the substrate 20c is chipped, the surface of the convex spherical lens 16 or the information recording medium 1 Can be prevented from being scratched. Further, by providing a surface protective layer such as a diamond-like carbon thin film on the surface of the substrate 20c on the side of the information recording medium 1, even if the substrate 20c contacts the information recording medium 1, a part or all of the substrate 20c can be formed. Chipping or damage to the surface of the convex spherical lens 16 or the surface of the information recording medium 1 can be more reliably avoided.

Embodiment 4 As shown in FIG. 7, a transparent substrate 20 on which an objective lens 15 and a convex spherical lens 16 are arranged
On the surface formed on the plane on the side of the information recording medium 1 on which the convex spherical lens 16 of d is provided, there is provided a buffer portion 22 projecting, for example, about several μm from the convex spherical lens 16. This buffer 2
2 is made of an elastic material such as hard rubber or the same material as the substrate 20d and is formed in a truncated cone, a semi-cylindrical surface, or a spherical surface.
Of the substrate 20d, or at four corners of the substrate 20d, or two at one end of the substrate 20d and one at the center of the other end.

As described above, the transparent substrate 20d on which the objective lens 15 and the convex spherical lens 16 are disposed protrudes by a predetermined height from the surface formed by the plane on the information recording medium 1 side on which the convex spherical lens 16 is provided. By providing the buffer portion 22, even if the convex spherical lens 16 side and the information recording medium 1 come into contact with each other due to mechanical characteristics of the information recording medium 1 itself or an external impact, it is possible to avoid direct contact with the convex spherical lens 16. Yes, substrate 2
0d is partially or entirely missing, or the convex spherical lens 16
Of the information recording medium 1 can be prevented from being scratched. Further, by forming the buffer portion 22 with an elastic body, it is possible to reliably prevent the surface of the information recording medium 1 from being damaged when the substrate 20d comes into contact with the information recording medium 1.

As shown in FIG. 8, for example, a spherical or saw-toothed fine structure portion 23 is formed on the surface of the buffer portion 22 formed of a truncated cone by using an inorganic material such as an organic material or glass, a hard rubber or the like. Or the same material as the substrate 20d. As described above, the fine structure portion 2 is formed on the surface of the buffer portion 22.
By providing 3, even if it comes into contact with the information recording medium 1,
Part or all of the substrate 20d can be reliably prevented from being chipped or the surface of the convex spherical lens 16 or the surface of the information recording medium 1 from being damaged.

Further, as shown in FIG. 9, the protective film on the surface of the information recording medium 1 on which the laser beam 19 is incident is coated with a solid lubricant such as diamond-like carbon or a polyfluoroether which transmits the laser beam 19. The lubricant layer 24 having a thickness of about several nm to several hundred nm may be formed using such a liquid lubricant or a surfactant. By forming the lubricant layer 24 on the recording / reproducing side surface of the information recording medium 1 as described above, when the microstructure portion 23 of the substrate 20 d comes into contact with the information recording medium 1, an impact is applied by the lubricant layer 24. The surface of the convex spherical lens 16 or the surface of the information recording medium 1 can be reliably prevented from being damaged.

In each of the above embodiments, the case where a high numerical aperture is obtained by using the objective lens 15 and the convex spherical lens 16 has been described. However, an aspheric lens may be used instead of the convex spherical lens 16. . Further, in each of the above embodiments, the case where the optical pickup device 6 irradiates the information recording medium 1 with light from the upper surface has been described. Light may be emitted from the lower surface of the recording medium 1.

[0028]

As described above, according to the present invention, the surface on the information recording medium side of the convex spherical lens of the information recording / reproducing optical device for condensing the information on the information recording medium through the objective lens and the convex spherical lens is formed as a curved surface. In addition, since the convex spherical lens is arranged at a very small distance from the information recording medium, even if the convex spherical lens and the information recording medium come into contact with each other while recording and reproducing information, one of the convex spherical lenses may be in contact with the information recording medium. Part or all is missing,
The surface of the convex spherical lens and the surface of the information recording medium can be prevented from being damaged.

Further, by forming an optical element by integrally disposing an objective lens and a convex spherical lens on a transparent substrate, and forming the surface of the optical element on the side of the information recording medium having the convex spherical lens with a curved surface, Even when the convex spherical lens and the information recording medium come into contact with each other during recording and reproduction of data, the convex spherical lens comes into contact with the curved surface of the optical element. And the surface of the information recording medium can be prevented from being damaged.

Further, by forming the peripheral portion of the surface on the information recording medium side having the convex spherical lens of the optical element in which the objective lens and the convex spherical lens are integrally disposed on a transparent substrate, the convex spherical lens and the information are formed. Even when the recording medium is in contact with the recording medium, it is possible to prevent the peripheral portion of the convex spherical lens from being chipped or the surface of the information recording medium from being damaged.

Further, by making the radius of curvature of the curved surface of the peripheral portion of the optical element asymmetrically different from the optical axes of the objective lens and the convex spherical lens, the mechanical characteristics when the information recording medium rotates in the radial direction are changed. An optical element can be arranged corresponding to the difference, and a margin for contact between the convex spherical lens and the information recording medium can be increased.

Further, by providing a buffer portion having a fixed height in a region other than the convex spherical lens on the surface of the optical element having the convex spherical lens on the side of the information recording medium, the mechanical characteristics of the information recording medium itself and the impact from the outside can be improved. Even if the convex spherical lens side and the information recording medium are in contact with each other, it is possible to avoid contact with the convex spherical lens, and it is possible to prevent the peripheral portion of the convex spherical lens from being chipped or the surface of the information recording medium from being scratched. it can.

Further, by providing the protruding fine structure portion on the surface of the buffer portion, even when the convex spherical lens side and the information recording medium come into contact with each other due to the mechanical characteristics of the information recording medium itself or an external impact, the convex spherical surface is formed. It is possible to avoid direct contact with the lens, and it is possible to prevent the peripheral portion of the convex spherical lens from being chipped or the surface of the information recording medium from being damaged.

Further, by forming a lubricant layer that transmits light on the surface of the information recording medium for recording and reproducing information on the side of the information recording / reproducing optical device, mechanical properties of the information recording medium itself and impact from the outside can be improved. Even if the convex spherical lens side contacts the information recording medium, the impact can be reduced by the lubricant layer, and the surface of the convex spherical lens and the information recording medium can be prevented from being scratched or damaged. .

Further, by using the information recording / reproducing optical device in the information recording / reproducing apparatus, it is possible to record and reproduce information stably.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of an optical pickup device.

FIG. 3 is an arrangement diagram of an objective lens and a convex spherical lens of the above embodiment.

FIG. 4 is a configuration diagram of a second embodiment.

FIG. 5 is a configuration diagram of a third embodiment.

FIG. 6 is another configuration diagram of the third embodiment.

FIG. 7 is a configuration diagram of a fourth embodiment.

FIG. 8 is another configuration diagram of the fourth embodiment.

FIG. 9 is a configuration diagram of an embodiment having a lubricant layer on the surface of an information recording medium.

[Explanation of symbols]

1; information recording medium; 3; control unit; 4; turntable;
5; rotary motor, 6; optical pickup device, 11; L
D, 12; collimator lens, 13; polarizing beam splitter, 14; quarter-wave plate, 15; objective lens, 16;
Convex spherical lens, 17; condenser lens, 18; light receiving element.

Claims (8)

[Claims] 1. An information recording / reproducing optical device for condensing a light beam emitted from a light source onto an information recording medium through an objective lens and a convex spherical lens, wherein a surface of the convex spherical lens on the information recording medium side is formed as a curved surface, An information recording / reproducing optical device, wherein a convex spherical lens is arranged at a small interval from an information recording medium. 2. An information recording / reproducing optical device for condensing a light beam emitted from a light source onto an information recording medium through an objective lens and a convex spherical lens, wherein the objective lens and the convex spherical lens are integrally disposed on a transparent substrate. Element, the surface of the optical element on the side of the information recording medium having the convex spherical lens is formed as a curved surface, and the surface of the optical element on the side of the convex spherical lens is arranged at a small distance from the information recording medium. Characteristic optical device for recording and reproducing information. 3. An information recording / reproducing optical device for condensing a light beam emitted from a light source onto an information recording medium through an objective lens and a convex spherical lens, wherein the objective lens and the convex spherical lens are integrally disposed on a transparent substrate. The surface of the optical element on the side of the information recording medium having the convex spherical lens is formed of a curved surface, and the surface of the optical element on the side of the convex spherical lens is arranged at a small distance from the information recording medium. An information recording / reproducing optical device, comprising: 4. The information recording / reproducing optical device according to claim 3, wherein a radius of curvature of a curved surface of a peripheral portion of the optical element is asymmetrically different from an optical axis of the objective lens and the convex spherical lens. 5. An information recording / reproducing optical device for condensing a light beam emitted from a light source onto an information recording medium through an objective lens and a convex spherical lens, wherein the objective lens and the convex spherical lens are disposed integrally on a transparent substrate. A buffer having a certain height is provided in a region other than the convex spherical lens on the surface of the information recording medium having the convex spherical lens of the optical element having the element, and the convex spherical lens side surface of the optical element is disposed on the information recording medium. An optical device for recording and reproducing information, wherein the optical device is arranged at a very small interval. 6. The information recording / reproducing optical device according to claim 5, further comprising a fine structure protruding from the surface of the buffer. 7. A lubricant layer for transmitting light to a surface of an information recording medium on which information is recorded and reproduced by the information recording and reproducing optical device according to claim 1. An information recording medium, characterized by having formed thereon. 8. An information recording / reproducing device comprising the information recording / reproducing optical device according to claim 1. Description: