JP2001256659A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup, capable of stably performing recording/ reproducing to/from an optical information recording medium having high density. SOLUTION: A focus deviation amount of a light spot projected on the optical information recording medium D is detected, based on a light receiving amount in respective light-receiving areas of a light receiving element 9, an auxiliary optical system 12 is moved in the optical axis direction A within a fine range by a drive means 14 according to the detected focus deviation amount, and the focus deviation of the optical spot projected on the optical information medium D is corrected. Thus, the focus deviation of the light spot, projected on the optical information recording medium D, is corrected while holding a fine distance between the optical information recording medium D and a spot-forming lens 11 and in the state that a relative position between the spot- forming lens 11 and an objective lens 10 is maintained with high precision, the size of a spot diameter of the light spot projected on the optical information recording medium D is stabilized in a fine state, and whereby recording/ reproducing to/from the optical information recording medium D having high density is performed stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical pickup device for recording / reproducing information on / from an optical information recording medium.

[0002]

2. Description of the Related Art In recent years, the density of an optical information recording medium such as an optical disk has been increasing. In order to perform recording and reproduction on such a high-density optical disk, it is necessary to reduce the size w (w∝λ / sin θ) of the spot diameter of the laser beam on the recording surface of the optical disk.
Here, θ is the emission angle of the objective lens, and λ is the wavelength of the laser light. The numerical aperture (NA) of the objective lens and the emission angle θ of the objective lens have a relationship of NA = sin θ.

In order to reduce the size w of the spot diameter of the laser beam on the recording surface of the optical disk, a high NA lens group is used, or a solid immersion lens (Solid Immers lens) is provided between the objective lens and the optical disk.
ion lens), and irradiating the recording surface of the optical disc through a solid immersion lens, thereby effectively increasing the NA and reducing the spot diameter size w. A system has been proposed (see, for example, JP-A-8-212579, JP-A-11-144293, and JP-A-11-149661).

By the way, in an optical pickup optical system having such a solid immersion lens, due to its characteristics, it is necessary to bring the solid immersion lens close to the recording surface of the optical disk to a distance less than the wavelength of the laser light. The diameter w cannot be reduced.

Accordingly, Japanese Patent Application Laid-Open No. 8-212579 and Japanese Patent Application Laid-Open
In the optical pickup device described in -149661,
An actuator for driving the solid immersion lens is provided independently of the actuator for driving the objective lens, and the actuator adjusts the distance between the solid immersion lens and the optical disk by slightly moving the solid immersion lens.

FIG. 8 is a sectional view showing an example of a conventional optical pickup device 100 using a solid immersion lens 101. As shown in FIG. 101 is a solid immersion lens, 102 is an objective lens, 103 is a support shaft, 104
Is a solid immersion lens holder, 105 is an electromagnetic drive unit, and 106 is an objective lens holder. Note that 107
Is an optical disk. According to the optical pickup device 100, the solid immersion lens holder 104 can be driven by the electromagnetic drive unit 105, so that the solid immersion lens 101 is driven independently of the objective lens 102, and thus the solid immersion lens 101 is The distance from the optical disk 107 can be adjusted.

In the optical pickup device described in Japanese Patent Application Laid-Open No. 11-144293, a solid immersion lens is mounted on a slider, and the slider is floated on the optical disk by the principle of an air bearing, so that the solid immersion lens and the optical disk are separated. The distance is secured.

FIG. 9 is a sectional view showing an example of a conventional optical pickup device 200 in which a solid immersion lens 201 is mounted on a slider. 201 is a solid immersion lens, 202 is an objective lens, 203 is a slider, 204 is a suspension, and 205 is a micro prism. Reference numeral 206 denotes an optical disk. According to the optical pickup device 200, the optical disk 206
By mounting the solid immersion lens 201 on the slider 203 that floats by the rotation of the optical disk 206, the solid immersion lens 201 can be positioned very close to the optical disk 206.

[0009]

It is known that the relative positional relationship between the solid immersion lens and the objective lens greatly affects the spot diameter size w on the optical disk. However, JP-A-8-2125
In the case where the solid immersion lens and the objective lens are independently driven as in the optical pickup device described in No. 79 or JP-A-11-149661, while maintaining a small distance between the optical disk and the solid immersion lens, In addition, maintaining the relative position between the solid immersion lens and the objective lens with high precision is very complicated and difficult in terms of method and mechanism.

On the other hand, when a solid immersion lens and an objective lens are mounted on a slider as in the optical pickup device described in JP-A-11-144293, the relative positions of the solid immersion lens and the objective lens are fixed. The distance between the optical disk and the solid immersion lens is maintained by the flying of the slider, so the thickness of the protective layer formed on the surface of the optical disk causes unevenness in the thickness of the solid immersion lens and the recording layer. Distance may fluctuate. Also, since the flying height of the slider changes depending on the linear velocity of the optical disk, the flying height of the slider fluctuates due to fluctuations in the rotation speed of the optical disk rotation mechanism and the difference in the linear velocity between the inner and outer circumferences of the optical disk. There is a problem that the size w of the spot diameter of the laser light changes. Further, there are manufacturing tolerances in the solid immersion lens and the objective lens constituting the optical pickup optical system of the optical pickup device, and to correct these, complicated adjustments must be made when fixing to the slider.

An object of the present invention is to make it possible to stabilize the size of a spot diameter of a light spot irradiated on an optical information recording medium in a minute state, and to stably perform recording / reproducing of a high-density optical information recording medium. An object of the present invention is to provide an optical pickup device that can perform the above operation.

[0012]

According to the first aspect of the present invention,
An optical pickup device for recording / reproducing information on / from an optical information recording medium, comprising: a light source for emitting light; an objective lens for converging light emitted from the light source; and a fixed distance from the objective lens. And provided with a small distance to the optical information recording medium,
A spot forming lens for irradiating the light converged by the objective lens on the optical information recording medium as a light spot, and at least one or more optical components, and the spot forming lens forms a spot on the optical information recording medium. An auxiliary optical system that corrects the defocus of the irradiated light spot; a driving unit that moves at least one or more of the optical components constituting the auxiliary optical system in a minute range; and a light receiving area divided into at least two or more. A light receiving element for receiving reflected light from the optical information recording medium, and a defocus amount of a light spot irradiated on the optical information recording medium based on a light receiving amount of light in each light receiving area of the light receiving element. A defocus detecting means for detecting the defocus, and a driving signal corresponding to the defocus amount detected by the defocus detecting means, to the driving means, Defocus correcting means for moving at least one or more of the optical components constituting the auxiliary optical system in a minute range in the optical axis direction to correct the defocus of a light spot irradiated on the optical information recording medium. .

Therefore, the amount of defocus of the light spot irradiated on the optical information recording medium is detected based on the amount of light received in each of the light receiving areas divided into at least two or more of the light receiving elements. Then, at least one or more optical components constituting the auxiliary optical system are moved in a minute range in the optical axis direction by the driving means according to the detected defocus amount, and the light spot irradiated on the optical information recording medium is irradiated. Is defocused. Thus, while maintaining the minute distance between the optical information recording medium and the spot forming lens and maintaining the relative position between the spot forming lens and the objective lens with high accuracy, the light is irradiated onto the optical information recording medium. It is possible to correct the defocus of the light spot.

According to a second aspect of the present invention, in the optical pickup device according to the first aspect, the objective lens and the spot forming lens are integrally held by a holding member with their optical axes aligned.

Therefore, since the objective lens and the spot forming lens are integrally held by the holding member in a state where the optical axes are aligned, the alignment of the optical axes of the lenses becomes unnecessary, and the objective lens and the spot are formed. It is possible to always maintain the relative position with respect to the forming lens with high accuracy.

According to a third aspect of the present invention, in the optical pickup device of the second aspect, the holding member is a slider which floats on the optical information recording medium by rotation of the optical information recording medium.

Therefore, the objective lens and the spot forming lens are integrally held by the slider,
The alignment of the optical axes of the lenses becomes unnecessary, and the relative position between the objective lens and the spot forming lens can always be maintained with high accuracy. Also, the flying height of the slider from the optical information recording medium due to the thickness unevenness of the protective layer of the optical information recording medium, the unevenness of the rotation speed of the rotating mechanism, and the difference in the linear velocity between the inner circumference and the outer circumference of the optical information recording medium. Even when a focus shift occurs due to the fluctuation of the optical information recording medium, while maintaining a small distance between the optical information recording medium and the spot forming lens,
In addition, defocus is corrected while maintaining the relative position between the spot forming lens and the objective lens with high accuracy. Further, the manufacturing tolerance of the spot forming lens and the objective lens can be corrected.

The invention according to claim 4 is the invention according to claim 2 or 3.
3. The optical pickup device according to claim 1, wherein the optical axis shift detection is provided on the holding member and around the objective lens, and has at least two or more divided light receiving regions for detecting the optical axis shift of the objective lens. A light receiving element for detecting an optical axis shift of the objective lens based on an amount of light received in each light receiving region of the light receiving element for detecting an optical axis shift, and an optical axis shift detecting means for detecting the optical axis shift. A drive signal corresponding to the determined optical axis shift amount is output to the drive unit, and at least one or more of the optical components constituting the auxiliary optical system are moved in a minute range in a direction orthogonal to the optical axis direction. And an optical axis shift correcting means for correcting the optical axis shift of the objective lens.

Therefore, the optical axis shift of the objective lens is detected based on the amount of light received in each of the light receiving areas divided into at least two or more of the optical axis shift detecting light receiving elements.
Then, at least one or more optical components constituting the auxiliary optical system are moved by a driving means in a minute range in a direction orthogonal to the optical axis direction according to the detected optical axis shift amount, and the light of the objective lens is The axis deviation is corrected. As a result, the optical axis deviation of the objective lens is corrected while maintaining the minute distance between the optical information recording medium and the spot forming lens and maintaining the relative position between the spot forming lens and the objective lens with high accuracy. It becomes possible to do.

[0020]

FIG. 1 shows a first embodiment of the present invention.
It will be described based on. The optical pickup device of the present embodiment is applied to an optical pickup device that performs recording and reproduction of an ultra-high-density optical disk, which is an optical information recording medium having a very high recording density.

Here, FIG. 1 is a configuration diagram schematically showing the optical pickup device 1. As shown in FIG. As shown in FIG. 1, an optical pickup device 1 according to the present embodiment includes a semiconductor laser 2 that emits laser light as a light source, a collimator lens 3, a polarizing beam splitter 4, a quarter-wave plate 5, An optical system 6 located on a high-density optical disc D;
And a four-division photodiode (hereinafter, referred to as a four-division PD) 9 which is a light receiving element and has a four-division PIN diode.
The optical system 6 includes an objective lens 10 and a solid immersion lens 11 which is a spot forming lens. The solid immersion lens 11 has a hemispherical shape in which the incident surface side of the laser beam from the semiconductor laser 2 is spherical and the other is flat, and is formed of a material having a high refractive index. Here, the solid immersion lens 1
The distance between the optical disk D and the recording surface of the optical disk D is
The interval is equal to or less than the wavelength of the laser light emitted from the laser beam.

A biconvex lens 12 functioning as an auxiliary optical system is provided between the quarter-wave plate 5 and the optical system 6 of the optical pickup device 1. In the present embodiment, the biconvex lens 12 is used as an optical component constituting the auxiliary optical system, but a plano-convex lens, a concave lens, or other optical components as long as they do not depart from the gist of the present invention. Alternatively, a combination of a plurality of lenses and optical components may be used.

The biconvex lens 12 has a lens holder 13
An electromagnetic drive mechanism 14 is provided on the outer periphery of the lens holder 13 and functions as a drive unit for moving the biconvex lens 12 in a minute range. The electromagnetic drive mechanism 14 includes a moving coil, a permanent magnet,
The voice coil motor is composed of a yoke.
In the present embodiment, the electromagnetic drive mechanism 14 constituted by a voice coil motor is used as the drive means. However, another electromagnetic drive mechanism may be used, or a drive mechanism other than electromagnetic drive such as piezoelectric ceramics may be used. good.

Next, a normal reproducing operation of the optical disk D in the optical pickup device 1 will be described. When reproducing an ultra-high-density optical disc D, the laser beam emitted from the semiconductor laser 2 is converted into substantially parallel light by the collimator lens 3 and then passes through the polarization beam splitter 4. After that, the laser light converted into circularly polarized light by the quarter-wave plate 5 is condensed by the biconvex lens 12 and the objective lens 10 and then largely refracted by being incident on the solid immersion lens 11 having a high refractive index. Then, the light converges on the bottom surface of the solid immersion lens 11 as a minute light spot. Here, since the solid immersion lens 11 and the recording surface of the ultra-high-density optical disk D have an interval equal to or smaller than the wavelength of the laser beam, the spot size of the light spot formed on the bottom surface of the solid immersion lens 11 is substantially the same. A light spot having a minute spot size converges on the recording surface of the optical disk D, and irradiates a mark recorded on the recording surface of the optical disk D. Thereafter, the reflected light from the recording surface of the optical disc D follows the reverse path, passes through the solid immersion lens 11, the objective lens 10, and the biconvex lens 12, and changes the polarization direction to 9 by the quarter-wave plate 5.
The light is converted into linearly polarized light rotated by 0 °, and is reflected by the polarization beam splitter 4 toward the detection lens 7. The light reflected by the polarization beam splitter 4 is condensed by the detection lens 7 and the cylindrical lens 8 and is divided into four PDs.
9 is incident. The four-segment PD 9 can reproduce the optical disc D by detecting the amount of reflected laser light received that changes according to the difference in reflected light that occurs depending on whether or not there is a mark on the recording surface of the optical disc D.

A control unit 15 having a microcomputer having a CPU (Central Processing Unit) and the like is connected to the four-division PD 9 of the optical pickup device 1. The control unit 15 adjusts the focal point on the recording surface of the optical disc D based on a signal output according to the amount of light received from each of the four divided PIN diodes of the quadrant PD 9 by a known method such as an astigmatism method. It has a first function of detecting a shift (focus shift detecting means). further,
The control unit 15 is connected to the electromagnetic driving mechanism 14 and outputs a driving signal to the electromagnetic driving mechanism 14 when detecting a defocus, and moves the biconvex lens 12 in the optical axis direction (arrow direction A). It has a second function of moving in a minute range (defocus correction means). The output of the drive signal from the control unit 15 to the electromagnetic drive mechanism 14 is continued until the focusing state is achieved.

Here, each of the four divided PDs of the four-divided PD 9 is
Detecting the defocus amount of the light spot irradiated on the optical disc D based on the amount of light received by the IN diode;
The biconvex lens 12 is moved in the optical axis direction (arrow direction A) in a minute range by the electromagnetic drive mechanism 14 according to the detected defocus amount, and the defocus of the light spot irradiated on the optical disk D is corrected. Thus, the light was irradiated onto the optical information recording medium while maintaining a small distance between the optical disc D and the solid immersion lens 11 and maintaining the relative position between the solid immersion lens 11 and the objective lens 10 with high accuracy. Since the defocus of the light spot can be corrected and the spot diameter of the light spot irradiated on the optical disc D can be stabilized in a minute state, the recording / reproducing of the high density optical disc D can be stabilized. Can be done.

Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 2 is a schematic diagram showing the optical pickup device 20. As shown in FIG. 2, the optical pickup device 20 of the present embodiment is different from the optical pickup device 1 of the first embodiment in that the PI
A two-division photodiode having an N diode (hereinafter, referred to as a photodiode)
It is called a two-part PD. ) 21 is provided in place of the quadrant PD 9 and the knife edge 22 is provided in place of the cylindrical lens 8. here,
A collimator lens 3, a polarizing beam splitter 4,
/ 4 wavelength plate 5, objective lens 10, solid immersion lens 11, detection lens 7, knife edge 22
Thus, an optical pickup optical system is configured.

Since the technique of detecting the focus shift using the two-part PD 21 and the knife edge 22 (knife edge method) is well known, the description thereof will be omitted. Each PI divided into two
A focus shift on the recording surface of the optical disc D is detected based on a signal output according to the amount of light received from the N diode, and a drive signal is output to the electromagnetic drive mechanism 14 according to the detected focus shift. Then, the biconvex lens 12 is moved in a minute range in the optical axis direction (arrow direction A) until the focusing state is achieved.

Here, the amount of defocus of the light spot irradiated on the optical disk D is detected based on the amount of light received by each of the four divided PIN diodes of the two-divided PD 21, and the detected defocus amount is calculated. Depending on the biconvex lens 12
Is moved in the optical axis direction (arrow direction A) in a minute range by the electromagnetic drive mechanism 14 to correct the defocus of the light spot irradiated on the optical disk D. Thereby, the optical disk D
Defocus of the light spot irradiated on the optical information recording medium while maintaining a small distance between the solid immersion lens 11 and the solid immersion lens 11 and maintaining the relative position between the solid immersion lens 11 and the objective lens 10 with high accuracy. Can be corrected and the size of the spot diameter of the light spot irradiated on the optical disc D can be stabilized in a minute state, so that the recording / reproducing of the high-density optical disc D can be performed stably. .

Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first and second embodiments described above are denoted by the same reference numerals, and the description is omitted.

Here, FIG. 3 is a configuration diagram schematically showing the vicinity of the optical element 30. As shown in FIG. 3, the present embodiment is an optical pickup device 1 according to the first embodiment described above.
The difference is that the optical system 6 (the objective lens 10 and the solid immersion lens 11) used in the optical pickup device 20 of the second embodiment is replaced with an optical element 30 only.

The optical element 30 integrally holds an objective lens 31 provided on the biconvex lens 12 side and a solid immersion lens 32 provided on the optical disk D side by a glass substrate 33 functioning as a holding member. It is constituted by. This solid immersion lens 32
Is made of a material having a hemispherical shape and a high refractive index. The objective lens 31 and the solid immersion lens 32 are held with their optical axes aligned. Further, the distance between the solid immersion lens 11 of the optical element 30 and the recording surface of the optical disk D is set to be equal to or less than the wavelength of the laser light emitted from the semiconductor laser 2.

Therefore, according to the optical element 30, since the objective lens 31 and the solid immersion lens 32 are integrally held by the glass substrate 33, the alignment of the optical axes of the lenses becomes unnecessary, and the objective lens 31 and the solid immersion lens 32 are not required. The relative position with respect to the solid immersion lens 32 can always be maintained with high accuracy.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same parts as those in the first and second embodiments described above are denoted by the same reference numerals, and the description is omitted.

FIG. 4 is a structural view schematically showing the vicinity of the optical element 40. As shown in FIG. As shown in FIG. 4, this embodiment is an optical pickup device 1 according to the first embodiment described above.
The only difference is that a floating type optical element 40 is provided instead of the optical system 6 (the objective lens 10 and the solid immersion lens 11) used in the optical pickup device 20 of the second embodiment.

The optical element 40 is a floating type optical element supported on the optical disk D by a suspension arm 41, and an objective lens 42 disposed on the biconvex lens 12 side and an objective lens 42 disposed on the optical disk D side. The solid immersion lens 43 is integrally fixed inside a slider 44 formed of a glass substrate or the like. This solid immersion lens 43 is formed of a material having a hemispherical shape and a high refractive index.
Further, the objective lens 42 and the solid immersion lens 4
3 is fixed so that the optical axes coincide with each other. A groove (not shown) for floating the optical element 40 by rotation of the optical disk D is formed on the bottom surface of the optical element 40, and the distance between the floating optical element 40 and the recording surface of the optical disk D is determined by a semiconductor. The interval is set to be equal to or less than the wavelength of the laser light from the laser 2.

Therefore, according to the optical element 40, the objective lens 42 and the solid immersion lens 43 are integrally fixed inside the slider 44, so that the alignment of the optical axes of the lenses becomes unnecessary and the objective lens 42 And the solid immersion lens 43 can always maintain the relative position with high accuracy.

The flying height of the optical element 40 from the optical disk D due to the thickness unevenness of the protective layer of the optical disk D, the unevenness of the rotation speed of the rotating mechanism, and the difference in the linear velocity between the inner circumference and the outer circumference of the optical disk D. When the focus shifts due to the fluctuation, as described above, a drive signal is output to the electromagnetic drive mechanism 14 in accordance with the detected focus shift, and the biconvex lens 12 is moved along the optical axis until the focus state is achieved. By moving in a small range in the direction (arrow direction A), defocus can be corrected easily and easily. Further, it is possible to correct the manufacturing tolerance of the solid immersion lens 43 and the objective lens 42.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. Note that the same parts as those in the third embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

Here, FIG. 5 is a configuration diagram schematically showing the vicinity of the optical element 50, and FIG. 6 is a plan view of the optical element 50 as viewed from above. As shown in FIG. 5, the present embodiment is different from the third embodiment in that an optical element 50 is provided instead of the optical element 30 used in the third embodiment.

As shown in FIGS. 5 and 6, the optical element 50 is a light receiving element for detecting an optical axis shift on the glass substrate 33 of the optical element 30 and around the objective lens 31.
Photodiodes 51 (51a, 51b, 51c,
51d). Therefore, these photodiodes 51 (51a, 51b, 51c, 51
d), when the optical element 50 has a lateral shift of the optical axis (see FIG. 7A) or a tilt of the optical axis (see FIG. 7B), the opposite side of the lateral shift direction or the tilt direction. The light transmitted through the biconvex lens 12 is incident on the photodiode 51 located on the opposite side.

The control unit 15 is also connected to the photodiodes 51. The control unit 15 controls the optical axis of the optical element 50 based on a signal output according to the amount of light received from each photodiode 51. And a third function (optical axis deviation detecting means) for detecting deviation (lateral deviation, inclination) of the optical axis. Then, the control unit 15 determines the lateral shift of the optical axis of the optical element 50 (see FIG. 7A) and the inclination of the optical axis of the optical element 50 (see FIG. 7B). When the detection is performed based on the signal output according to the above, a drive signal is output to the electromagnetic drive mechanism 14, and the biconvex lens 12 is moved in a minute range in a direction orthogonal to the optical axis direction (arrow direction B). And a fourth function (optical axis deviation correcting means). Such a control unit 15
The output of the drive signal to the electromagnetic drive mechanism 14 is continued until the lateral displacement and the inclination of the optical axis are corrected.

Here, four photodiodes 51 (5
1a, 51b, 51c, 51d), the optical axis deviation of the objective lens 31 is detected based on the amount of light received, and the biconvex lens 12 is moved by the electromagnetic drive mechanism 14 according to the detected optical axis deviation. It moves in a minute range in a direction perpendicular to the direction (arrow direction B) to correct the optical axis shift of the objective lens 31. Thereby, the optical axis deviation of the objective lens 31 is corrected while maintaining the minute distance between the optical disc D and the solid immersion lens 32 and maintaining the relative position between the solid immersion lens 32 and the objective lens 31 with high accuracy. Since the size of the spot diameter of the light spot irradiated on the optical disc D can be stabilized in a minute state, recording / reproducing of the high-density optical disc D can be performed stably.

[0045]

According to the first aspect of the present invention, there is provided an optical pickup device for recording / reproducing information on / from an optical information recording medium, comprising: a light source for emitting light; and a light source for converging light emitted from the light source. An objective lens, which is provided at a fixed distance from the objective lens, and is provided at a small distance to the optical information recording medium, and records the light converged by the objective lens on the optical information recording medium. A spot forming lens for irradiating the medium as a light spot,
An auxiliary optical system configured of at least one or more optical components and configured to correct a defocus of a light spot irradiated on the optical information recording medium by the spot forming lens; and at least one or more of the auxiliary optical system configuring the auxiliary optical system Driving means for moving the optical component in a minute range, a light receiving element having at least two or more divided light receiving areas, receiving light reflected from the optical information recording medium, and irradiating the optical information recording medium A defocus detecting means for detecting the defocus amount of the light spot detected based on the amount of light received in each light receiving area of the light receiving element; and a driving signal corresponding to the defocus amount detected by the defocus detecting means. The information is output to the driving means, and at least one or more of the optical components constituting the auxiliary optical system are moved in a minute range in the optical axis direction to illuminate the optical information recording medium. Defocus correction means for correcting the defocus of the selected light spot, the light radiated onto the optical information recording medium based on the amount of light received in each light receiving area divided into at least two or more light receiving elements. The defocus amount of the spot is detected, and at least one or more optical components constituting the auxiliary optical system are moved in a minute range in the optical axis direction by the driving means in accordance with the detected defocus amount, and are moved on the optical information recording medium. By correcting the defocus of the light spot irradiated on the lens, the relative distance between the spot forming lens and the objective lens is maintained with high accuracy while maintaining the minute distance between the optical information recording medium and the spot forming lens. In this state, the defocus of the light spot irradiated on the optical information recording medium can be corrected, and the size of the spot diameter of the light spot irradiated on the optical information recording medium can be reduced. Can be stabilized in the state, the recording / reproducing of the high density optical information recording medium can be performed stably.

According to the second aspect of the present invention, in the optical pickup device according to the first aspect, the objective lens and the spot forming lens are integrally held by the holding member with the optical axes aligned. This makes it unnecessary to align the optical axes of the lenses, and can always maintain the relative position between the objective lens and the spot forming lens with high accuracy.

According to the third aspect of the present invention, in the optical pickup device according to the second aspect, the holding member is a slider that floats on the optical information recording medium by rotation of the optical information recording medium. , The alignment of the optical axes of the lenses can be eliminated,
The relative position between the objective lens and the spot forming lens can always be maintained with high accuracy. Also, the flying height of the slider from the optical information recording medium due to the thickness unevenness of the protective layer of the optical information recording medium, the unevenness of the rotation speed of the rotating mechanism, and the difference in the linear velocity between the inner circumference and the outer circumference of the optical information recording medium. Even if the focus shift occurs due to the fluctuation of the distance, the relative position between the spot forming lens and the objective lens can be adjusted with high accuracy while maintaining the minute distance between the optical information recording medium and the spot forming lens. It is possible to correct the defocus while maintaining it. Further, it is possible to correct the manufacturing tolerance of the spot forming lens and the objective lens.

According to a fourth aspect of the present invention, in the optical pickup device according to the second or third aspect, the optical pickup device is provided on the holding member and around the objective lens, and detects an optical axis shift of the objective lens. An optical axis shift detecting light receiving element having at least two divided light receiving areas for detecting the optical axis shift, and an optical axis shift of the objective lens based on an amount of light received in each light receiving area of the optical axis shift detecting light receiving element. An optical axis deviation detecting means for detecting the optical axis deviation, and outputting a drive signal corresponding to the optical axis deviation amount detected by the optical axis deviation detecting means to the driving means, and forming at least one or more of the auxiliary optical system An optical axis shift correcting means for correcting the optical axis shift of the objective lens by moving the optical component in a minute range in a direction orthogonal to the optical axis direction, and at least a light receiving element for optical axis shift detection. An optical axis shift amount of the objective lens is detected based on an amount of light received in each of the light receiving areas divided into two or more, and at least one or more optics constituting an auxiliary optical system according to the detected optical axis shift amount. The component is moved by a driving means in a minute range in a direction orthogonal to the optical axis direction,
By correcting the deviation of the optical axis of the objective lens, it is possible to maintain the minute distance between the optical information recording medium and the spot forming lens, and maintain the relative position between the spot forming lens and the objective lens with high accuracy. In addition, the optical axis deviation of the objective lens can be corrected, and the size of the spot diameter of the light spot irradiated on the optical information recording medium can be stabilized in a very small state. Recording / reproduction can be performed stably.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram schematically showing an optical pickup device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram schematically showing the vicinity of an optical element according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram schematically showing the vicinity of an optical element according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram schematically showing the vicinity of an optical element according to a fifth embodiment of the present invention.

FIG. 6 is a plan view of the optical element as viewed from above.

FIGS. 7A and 7B are explanatory diagrams illustrating a state in which the optical element has a lateral shift in the optical axis and a state in which the optical element has a tilt in the optical axis.

FIG. 8 is a configuration diagram schematically showing an example of a conventional optical pickup device.

FIG. 9 is a configuration diagram schematically showing another example of a conventional optical pickup device.

[Explanation of symbols]

 1,20 Optical pickup device 2 Light source 9,21 Light receiving element 10,31,42 Objective lens 11,32,43 Spot forming lens 12 Auxiliary optical system 14 Driving means 33 Holding member 44 Slider 51 Optical axis deviation detecting light receiving element D Optical information recording medium

Claims (4)

[Claims] 1. An optical pickup device for recording / reproducing information on / from an optical information recording medium, comprising: a light source for emitting light; an objective lens for converging the light emitted from the light source; Spot formation that is provided at a fixed distance from the optical information recording medium and is provided at a minute distance from the optical information recording medium, and irradiates the light converged by the objective lens as a light spot on the optical information recording medium. An auxiliary optical system, which comprises at least one or more optical components, and corrects a defocus of a light spot irradiated onto the optical information recording medium by the spot forming lens; and A drive unit for moving at least one or more of the optical components in a minute range; and a light receiving area divided into at least two or more sections. A light receiving element for receiving light reflected from a body, and a defocus detecting means for detecting a defocus amount of a light spot irradiated on the optical information recording medium based on an amount of light received in each light receiving region of the light receiving element. And outputting a drive signal corresponding to the amount of defocus detected by the defocus detecting means to the driving means, so that at least one or more of the optical components constituting the auxiliary optical system are within a small range in the optical axis direction. A focus shift correcting means for correcting a focus shift of a light spot irradiated on the optical information recording medium by moving the optical spot on the optical information recording medium. 2. The optical pickup device according to claim 1, wherein the objective lens and the spot forming lens are integrally held by a holding member with their optical axes aligned. 3. The optical pickup device according to claim 2, wherein the holding member is a slider that floats on the optical information recording medium by rotating the optical information recording medium. 4. A light receiving device for detecting an optical axis shift which is provided on the holding member and around the objective lens and has at least two or more divided light receiving areas for detecting an optical axis shift of the objective lens. An element, an optical axis shift detecting means for detecting an optical axis shift of the objective lens based on an amount of light received in each light receiving area of the optical axis shift detecting light receiving element, and an optical axis shift detecting means for detecting the optical axis shift. A drive signal corresponding to the optical axis shift amount is output to the drive unit, and at least one or more of the optical components constituting the auxiliary optical system are moved in a minute range in a direction orthogonal to the optical axis direction. 4. The optical pickup device according to claim 2, further comprising: an optical axis shift correcting unit that corrects an optical axis shift of the objective lens.