JP2000057608A - Optical pickup, information reproducing device and information recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup capable of detecting a tilt between a recording medium and an optical axis of a light beam with a simple constitution and exactly detecting the tilt of even an unrecorded recording medium in the optical pickup optically recording/reproducing information. SOLUTION: This device is provided with a laser diode 8 emitting the light beam B, an objective lens 2 separating the light beam B to a recording/ reproducing light beam B1 for recording/reproducing information and a detection light beam B2 for detecting the tilt of an optical disk 1, a detector 7 generating a light receiving signal Sp based on a recording/reproducing reflection beam PD from the information recording surface 1a of the recording/reproducing light beam B1 and a signal processing part generating a radial error signal Sre, etc., showing the tilt based on a detection reflective beam from the information recording surface 1a of the detection light beam B2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an optical pickup for optically recording and reproducing information on a recording medium, and an information reproducing apparatus and an information recording apparatus including the optical pickup. An optical pickup that detects an inclination between an information recording surface of the recording medium and an optical axis of a light beam used for recording and reproducing information, and performs recording and reproduction of information while compensating for the inclination, and information reproduction including the optical pickup. It belongs to the technical field of devices and information recording devices.

[0002]

2. Description of the Related Art Conventionally, for example, when information is optically recorded / reproduced on a disk-shaped recording medium such as a CD (Compact Disk), a light beam is applied to an information recording surface of the disk-shaped recording medium. In general, information is recorded and reproduced by condensing light.

[0003] Here, the angle between the optical axis of the light beam and the information recording surface should be a right angle in any direction (ie, the radial direction or the tangential direction in the disk-shaped recording medium). However, in actuality, for example, due to bending or the like due to aging of the disk-shaped recording medium,
The angle may deviate from a right angle in the radial direction or the tangential direction, that is, the information recording surface may be inclined with respect to the optical axis of the light beam (hereinafter, this inclination is simply referred to as tilt).

When this tilt occurs,
In the case where wavefront aberration such as so-called coma aberration occurs in the irradiation range of the light beam on the information recording surface, and the shape of the irradiation range is deformed from the original substantially circular shape, the information cannot be accurately recorded and reproduced. Come up.

Therefore, in the conventional optical pickup, the tilt is detected, and based on the detected tilt, a phase difference is given to the light beam in advance by, for example, a liquid crystal panel or the like disposed on the optical path of the light beam, and then the information is obtained. Measures are taken such as irradiating the recording surface to cancel the wavefront aberration due to the tilt.

Heretofore, conventionally, as a method of detecting the tilt, for example, a light beam different from a light beam for recording and reproducing information is applied to the information recording surface, and the reflected light is applied to the disk-shaped recording medium. A method in which light is received by two detectors divided in the radial direction, respectively, and a difference signal between the received light signals is used as a signal indicating a tilt in the radial direction, or crosstalk between adjacent tracks on a disk-shaped recording medium is canceled. A method of detecting tilt by comparing crosstalk detected by a crosstalk erasing device between three adjacent tracks is generally used.

[0007]

However, when a light beam dedicated to the above-mentioned tilt detection is used, an additional light source is required in addition to a light source for emitting a light beam for recording and reproduction. There is also a problem that a detector dedicated for detection is required, and the configuration of the optical pickup is complicated.

In the method using a signal output from the crosstalk erasing device, a crosstalk signal itself cannot be obtained from a recording medium on which no information is recorded. There was also a problem that detection was not possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an optical pickup for optically recording and reproducing information, with a simple configuration of an information recording surface and a light beam. An optical pickup capable of detecting the inclination with respect to the optical axis and accurately detecting the inclination even in an unrecorded recording medium, and an information recording apparatus including the optical pickup; An object of the present invention is to provide an information reproducing apparatus.

[0010]

According to the first aspect of the present invention, there is provided an information recording apparatus, comprising: irradiating a light beam such as a laser beam onto an information recording surface of a recording medium such as an optical disk to record information. In an optical pickup for reproducing, an emitting means such as a laser diode for emitting the light beam, a recording / reproducing light beam for recording / reproducing the information, the information recording surface, and the recording / reproducing light. Separation means such as an objective lens for separating the light beam from the optical axis of the beam into a detection light beam for detecting the inclination thereof, and a recording / reproducing reflected light which is a reflected light from the information recording surface of the recording / reproducing light beam A light receiving unit such as a detector that generates a light receiving signal based on the detected light beam, and a tilt error signal indicating the tilt is generated based on detected reflected light that is reflected light of the detected light beam from the information recording surface. And a generation means such as a No. processor.

Accordingly, the emitted light beam is separated to obtain a detection light beam, and the inclination of the recording medium is detected by using the detection light beam. Therefore, it is not necessary to use another light beam light source dedicated to the inclination detection. Tilt can be detected.

Further, since the recording / reproducing light beam and the detection light beam are separately used, loss of reflected light of the recording / reproducing light beam caused by detecting inclination using a part of the recording / reproducing light beam can be prevented. it can.

Furthermore, even when no information is recorded on the recording medium, the detected reflected light can be obtained, so that the inclination of the unrecorded recording medium can be accurately detected.

According to a second aspect of the present invention, there is provided an optical pickup according to the first aspect, wherein the separating means records the central portion of the cross section of the emitted light beam in the recording area. It is configured to be a condensing unit such as an objective lens that condenses the light beam on the information recording surface as a reproduction light beam and transmits the light beam in an annular area other than the central portion in the cross section as the detection light beam. .

Therefore, since the recording / reproducing light beam and the detection light beam are separated by the condensing means for condensing the recording / reproducing light beam on the information recording surface, the inclination of the recording medium can be simplified while simplifying the structure of the optical pickup. Can be detected.

According to a third aspect of the present invention, there is provided an optical pickup according to the second aspect, wherein the generating means includes a polarization hologram element or the like for converging the annular detection reflected light. Detecting reflected light condensing means, detecting light receiving means such as a partial detector for receiving the collected annular detected reflected light and generating a detected light receiving signal, and the tilt based on the generated detected light receiving signal Error signal generating means such as a signal processing unit for generating an error signal.

[0017] Therefore, since the annular detection reflected light is received as it is and an inclination error signal is generated, the inclination of the recording medium in any direction can be detected.

According to a fourth aspect of the present invention, there is provided an optical pickup according to the third aspect, wherein the detecting light receiving means is provided on the substrate on which the light receiving means is formed. The detection light receiving means is formed in an annular area surrounding the means, and the inner detection means such as a partial detector formed in an area inside the annular area corresponding to the width of the annular detection reflected light. Light receiving means;
Outer detection light receiving means such as a partial detector formed in an area other than the area in which the inner detection light receiving means in the annular area is formed, and the inner detection light receiving means has A plurality of first partial detection light receiving means such as partial detectors radially divided around the center position of the light receiving means by one or more division lines having a direction corresponding to the direction, and further comprising the outer detection light receiving means. The means is constituted by a plurality of second partial detection light receiving means such as partial detectors radially divided around the center position by the division line.

Therefore, since the detection light receiving means is detected on the substrate on which the light receiving means is formed, the light receiving means for information recording and reproduction and the detection light receiving means for tilt detection are integrated on one substrate. be able to.

The detecting light receiving means is divided into an inner detecting light receiving means and an outer detecting light receiving means, and the inner detecting light receiving means is constituted by a plurality of first partial detecting light receiving means. , The inclination can be reliably detected in accordance with the direction of the inclination to be detected.

According to a fifth aspect of the present invention, there is provided an optical pickup according to the fourth aspect, wherein the recording medium is a disk-shaped recording medium, and the inclination is the disk-shaped recording medium. Including a radial inclination in the medium and a tangential inclination in the disc-shaped recording medium, the inner detection light receiving means and the outer detection light receiving means are radial dividing lines which are the dividing lines parallel to the radial direction. And the tangential direction dividing line, which is the dividing line parallel to the tangential direction, is divided into four first partial detection light receiving means and second partial detection light receiving means, respectively.
Further, the error signal generating means includes the detected light receiving signal output from the radial second partial detection light receiving means, which is the two second partial detection light receiving means adjacent via the radial dividing line, and the radial direction The two first partial detection light receiving means, which are two first partial detection light receiving means adjacent to each other via a division line and on the opposite side of the tangential division line from the second radius detection light receiving means, respectively output A sum signal of the detected light reception signal and the detected light reception signals respectively output from the two second partial detection light reception means of the second partial detection light reception means other than the radius second partial detection light reception means. The first partial light receiving detecting means,
A difference signal between the detected light reception signal and a sum signal output from the two first partial light reception detection means other than the partial detection light reception means is output as the inclination error signal indicating the inclination in the radial direction. It is configured.

Therefore, the sum signal of the detected light receiving signals respectively outputted from the second radius detecting light receiving means and the detected light receiving signals respectively outputted from the first radial detecting light receiving means, and Detection light reception signals respectively output from the second partial detection light receiving means other than the second radius partial detection light receiving means and output from the first partial light reception detection means other than the first partial light detection detection means among the first partial light reception detection means, respectively. Since a difference signal between the detected light reception signal and the sum signal is output as a tilt error signal indicating a tilt in the radial direction, a tilt error signal in the radial direction can be accurately generated.

According to a sixth aspect of the present invention, there is provided an optical pickup according to the fifth aspect, wherein the error signal generating means comprises two adjacent signals via the tangential direction dividing line. The tangential second part is adjacent to the detected light receiving signal output from the tangential second part detecting light receiving means, which is the second part detecting light receiving means, via the tangential dividing line and the radial tangential dividing line. A sum signal of the detected light receiving signal output from each of the tangential first partial detecting light receiving means, which is the two first partial detecting light receiving means on the opposite side to the detecting light receiving means, and the second partial detecting light receiving means The detected light receiving signal output from each of the two second partial detecting light receiving means other than the tangential second partial detecting light receiving means and the tangential first partial detecting light receiving means out of the first partial light receiving detecting means. Consists of two of said first portion receiving and detecting means a difference signal between a sum signal of the detection light reception signals respectively outputted to output as the inclined error signal indicating the inclination of the tangential direction.

Therefore, the sum signal of the detected light receiving signals respectively outputted from the tangential second part detecting light receiving means and the detected light receiving signals respectively outputted from the tangential first part detecting light receiving means, and the second partial detecting light receiving means Detected light receiving signals respectively output from the second partial detection light receiving means other than the tangential second partial detection light receiving means and output from the first partial light receiving detecting means other than the tangential first partial detection light receiving means among the first partial light receiving detecting means, respectively. Since a difference signal between the detected light reception signal and the sum signal is output as a tilt error signal indicating a tangential tilt, a tangential tilt error signal can be accurately generated.

Further, both the tilt error signal indicating the tilt in the radial direction and the tilt error signal indicating the tilt in the tangential direction can be simultaneously generated by the same detecting and receiving means.

According to a seventh aspect of the present invention, there is provided an optical pickup according to any one of the third to sixth aspects, wherein the detection reflected light condensing means is a polarization hologram element. Is formed.

Therefore, the detected reflected light focusing means can be configured with a simple configuration.

In order to solve the above-mentioned problem, the invention according to claim 8 is directed to the optical pickup according to any one of claims 1 to 7, wherein the optical pickup according to any one of claims 1 to 7 transmits the recording / reproducing light beam based on the received light signal. The apparatus further includes a focus error signal generation unit such as a signal processing unit that generates a focus error signal indicating a shift between a focal position and a position of the information recording surface in a direction perpendicular to the information recording surface.

Therefore, a focus error signal can be generated together with the tilt error signal indicating the tilt of the recording medium.

According to a ninth aspect of the present invention, there is provided an optical pickup according to any one of the first to eighth aspects, wherein information to be reproduced is recorded on the recording medium. And a detection signal generating means such as a reproducing unit for generating a detection signal corresponding to the information based on the light receiving signal.

Therefore, it is possible to generate a detection signal together with the tilt error signal indicating the tilt of the recording medium.

In order to solve the above-mentioned problems, the present invention is directed to claim 10.
The optical pickup according to claim 9 includes:
A focus servo unit such as a driver that controls the focus position based on the focus error signal; a compensation unit such as a tilt driver that compensates the tilt based on the tilt error signal; and the information based on the detection signal. A reproducing unit such as a reproducing unit.

Therefore, the inclination of the recording medium can be accurately detected and compensated for, and the information can be reproduced accurately.

[0034] In order to solve the above-mentioned problems, the present invention is directed to claim 11.
The optical pickup according to claim 9 includes:
A focus servo unit such as a driver that controls the focus position based on the focus error signal; a compensation unit such as a tilt driver that compensates the tilt based on the tilt error signal; and the information based on the detection signal. A reproducing unit such as a reproducing unit that reproduces and outputs a reproduction signal; and controls the light beam based on the output reproduction signal and recording information to be recorded on the recording medium, and records the recording information on the information recording surface. Recording means such as an encoder for recording the data.

Therefore, the inclination of the recording medium can be accurately detected and compensated for, and information can be accurately recorded.

[0036]

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

(I) Principle of the Invention First, before describing the embodiments in detail, the principle of the present invention will be described.

In the above-described conventional optical pickup, not all of the light beam emitted from the light source is applied to the recording medium, but a part of the light beam (usually, a central portion in a cross section of the light beam) is formed. The light is condensed and irradiated on the recording medium, and the remaining light beam (circular annular portion in the cross section of the light beam) is reflected on an aperture limiting member provided in the objective lens to be irradiated on the recording medium. In general, it has been practiced to prevent the light from being dispersed or refracted light by the aperture limiting member to scatter the light in a region other than the recording medium.

Therefore, the present invention utilizes a light beam (a beam having a circular cross section) in the peripheral portion, which has not been conventionally used, to provide a space between an information recording surface of an optical disk as a recording medium and the optical axis of the light beam. In the radial direction (hereinafter, simply referred to as a radial direction) (i.e., a deviation from the right angle of the angle between the information recording surface and the optical axis; hereinafter, simply referred to as a radial tilt) and the direction thereof. The amount and direction of tilt (hereinafter, simply referred to as tangential tilt) in the tangential direction (hereinafter, simply referred to as tangential direction) of the optical disk are detected.

Next, the principle of the present invention will be described more specifically with reference to FIGS.

FIG. 1 is a block diagram showing a schematic configuration of an optical system showing the principle of the present invention, FIG. 2 is a diagram showing the principle of the present invention, and FIG. 3 is a plan view showing a divided shape of the detector. FIG. 4 is a diagram showing the tilt in each direction and the light receiving state of detection reflected light described later.

First, the configuration of an optical system used for explaining the principle will be described with reference to FIG.

As shown in FIG. 1, an optical system S for explaining the principle includes a laser diode 8 as an emitting means for emitting a light beam B for recording and reproduction, and a deflection beam for reflecting the emitted light beam B. A splitter 4, a collimator lens 3 for converting the reflected light beam B into parallel light, and rotating a plane of polarization of the parallel light beam B, and a reflection light of the light beam B from the optical disc 1 described later. A λ / 4 plate 6 for converting to linearly polarized light, and a recording / reproducing beam B1, which is a light beam at the center of the cross section of the light beam B whose polarization plane is rotating, are focused on an information recording surface 1a in the optical disc 1 and An objective lens 2 as a condensing means and a separating means for transmitting a detection light beam B2, which is a peripheral light beam in a cross section of the light beam B, and a light beam as a recording medium having an information recording surface 1a. The disk 1 transmits the recording / reproducing reflected light PD, which is the reflected light of the recording / reproducing light beam B1 reflected by the information recording surface 1a, and transmits the detection reflected light RD, which is also the reflected light of the detected light beam B2. A polarization hologram element 9 serving as a condensing means for detecting and reflecting light, which is condensed on a detector 7 described later, and an objective lens 2, a collimator lens 3, and a deflecting beam splitter which are rotated by a deflecting surface reflected by the information recording surface 1a. A condensing lens 5 for condensing the recording / reproducing reflected light PD and the detection reflected light RD transmitted through 4 on a detector 7, and a detector 7 as a light receiving means for receiving the recording / reproducing reflected light PD and the detected reflected light RD.
, And is constituted.

At this time, the objective lens 2 is formed at the central portion of the objective lens 2, and separates the recording / reproducing light beam B1 from the original light beam B and separates it from the information recording surface 1.
and a converging section 2b for converging light on the optical lens 1 and a detection light beam B2 formed in an annular shape around the condensing section 2b of the objective lens 2 to separate the detection light beam B2 from the original light beam B and leave it on the optical disk 1. And a transmission section 2a for irradiating the polarization hologram element 9 while irradiating and irradiating the detection reflected light RD.

The polarization hologram element 9 transmits the collimated light beam B before collimation by the collimator lens 3 and the recording / reproducing reflected light PD without any action. The detection reflected light RD is converged annularly on the detector 7.

In the above configuration, the light beam B
Is emitted from a laser diode 8, passes through a deflection beam splitter 4, a collimator lens 3, a polarization hologram element 9, a λ / 4 plate 6, and an objective lens 2 to generate a recording / reproducing light beam B1 and a detection light beam B2. To the information recording surface 1a.

The recording / reproducing light beam B1 applied to the information recording surface 1a is reflected by the information recording surface 1a, and the objective lens 2, the λ / 4 plate 6, the polarization hologram element 9, the collimator lens 3, The central portion of the detector 7 is irradiated as the recording / reproducing reflected light PD via the beam splitter 4 and the condenser lens 5.

On the other hand, the detection light beam B2 applied to the information recording surface 1a is reflected by the information recording surface 1a,
The light is applied to the polarization hologram element 9 via the objective lens 2 and the λ / 4 plate 6, is refracted by the polarization hologram element 9 so as to be converged annularly on the detector 7, and is further collimated by the collimator lens 3, the deflection beam splitter 4, An annular area surrounding the irradiation area of the recording / reproducing reflected light PD of the detector 7 is irradiated as the detected reflected light RD via the condenser lens 5.

Next, in the optical system S having such a configuration, when the optical disc 1 is tilted from its original position (ie, the position where the information recording surface 1a and the optical axis of the recording / reproducing light beam B1 are perpendicular). How the irradiation range of the recording / reproducing reflected light PD and the irradiation range of the detected reflected light RD on the detector 7 change when the radial tilt or the tangential tilt occurs will be described with reference to FIG. I do.

FIGS. 2A to 2C respectively show only the optical path of the recording / reproducing reflected light PD and the optical path of the detected reflected light RD.

First, as shown in FIG. 2A, when neither the radial tilt nor the tangential tilt occurs on the optical disc 1, as shown in the left of FIG. Since the optical axis coincides with the central axis of the detected reflected light RD (the central axis of the annular detected reflected light RD), the recording / reproducing reflected light PD is irradiated onto the detector 7 as shown in FIG. The range and the irradiation range of the detection reflected light RD on the detector 7 are mutually concentric.

However, as shown in FIG.
If, for example, a radial tilt occurs in the optical disc 1, the optical axis of the recording / reproducing reflected light PD and the detected reflected light RD
2A, the irradiation range of the recording / reproducing reflected light PD on the detector 7 is the same as that in FIG. 2A, but the irradiation range of the detected reflected light RD on the detector 7 is not It will be shifted in the direction corresponding to the direction of the generated radial tilt. Then, as shown in FIG.
(B) As shown on the right, the irradiation range of the recording / reproducing reflected light PD and the irradiation range of the detected reflected light RD are not concentric.

Here, the shift amount of the irradiation range of the detection reflected light RD is proportional to the amount of the generated radial tilt.

On the other hand, as shown on the left side of FIG. 2C, for example, when the objective lens 2 itself is displaced in a direction parallel to the information recording surface 1a due to so-called tracking servo control, etc. The width of the region of the polarization hologram element 9 through which the detection reflected light RD is transmitted (more specifically, the width of the annular region) is determined by the width of the cross section of the detection reflection light RD (more specifically, By making the width sufficiently smaller than the width of the annular detection reflected light RD), the optical axis of the recording / reproducing reflected light PD and the optical axis of the detected reflected light RD can be kept to be parallel to each other. As a result, Even when the objective lens 2 itself is displaced in a direction parallel to the information recording surface 1a, as shown in the right of FIG. 2C, the irradiation range of the recording / reproducing reflected light PD on the detector 7 and the detected reflected light R
The irradiation range on the detector 7 of D is mutually concentric as in the case of FIG.

As described above, when a radial tilt or a tangential tilt occurs, the detection reflected light RD
In view of the fact that the irradiation range moves by the direction and the amount corresponding to the tilt direction and the amount of the generated tilt, in the present invention, the recording / reproducing reflected light PD and the detected reflected light RD are both shown in FIG. And 13 partial detectors 7a to 7
The light is received using the detector 7 divided into n.

At this time, the partial detectors 7a, 7e, 7
Region including j, 7m, 7h and 7d and partial detector 7
The linear division line LR that divides the region including b, 7f, 7k, 7l, 7g, and 7c is formed so as to be parallel to the radial direction of the optical disc 1, while the partial detectors 7a, 7b, 7e, and 7f are formed. , 7j, and 7k and a linear dividing line LT that divides a region including the partial detectors 7d, 7c, 7h, 7g, 7m, and 7l into a tangential direction on the optical disk 1.

Further, the area of the circular area including the partial detectors 7j, 7k, 7l, and 7m is wider than the area of the irradiation area of the recording / reproducing reflected light PD, and is smaller than the area of the detection reflected light RD in the annular irradiation area. It is formed so as to be narrower than a region surrounded by the peripheral boundary line (a region on the center side of the detector 7).

Further, an annular area including partial detectors 7a, 7b, 7c and 7d as outer detection light receiving means and partial detectors 7e, 7f and 7g as inner detection light receiving means.
And 7h, the circular division line RL of the detected reflected light RD on the detector 7 when neither the radial tilt nor the tangential is generated on the optical disc 1. Coincides with the center line of the annular irradiation range (see the right of FIG. 2 (a)) (a circular center line that continuously connects the midpoint between the inner boundary line and the outer boundary line in the annular irradiation region) It is formed so that.

In the present invention, a radial error signal Sre indicating a radial tilt and a tangential error signal S
Generate te. That is,

Sre = (“7a” + “7b” + “7g” + “7h”) − (“7e” + “7f” + “7c” + “7d”) (1) Ste = (“7a” + "7d" + "7f" + "7g")-("7b" + "7c" + "7e" + "7h") (2) In the formula (1) or (2), "7a""Indicates the output value of the output signal from the partial detector 7a," 7b "indicates the output value of the output signal from the partial detector 7b, and" 7c "
Represents the output value of the output signal from the partial detector 7c,
d "is the output value of the output signal from the partial detector 7d,
“7e” indicates the output value of the output signal from the partial detector 7e, “7f” indicates the output value of the output signal from the partial detector 7f, “7g” indicates the output value of the output signal from the partial detector 7g, and “7h” Indicates the output value of the output signal from the partial detector 7h.

Then, if the radial error signal Sre is generated as in the equation (1), when there is no radial tilt, that is, as shown in FIG. 4A or FIG. When the light is irradiated on the detector 7, the first term on the right side and the second term on the right side of Expression (1) become equal, and as a result, the output value of the radial error signal Sre becomes “0”.

However, when there is a radial tilt, that is, when the detection reflected light RD is applied to the detector 7 as shown in FIG. 4B or FIG. The first term is not equal to the second term on the right side (in the case shown in FIG. 4B or FIG. 4D, the first term on the right side is larger than the second term on the right side), and as a result, the radial error The output value of the signal Sre is no longer “0” (it becomes positive in the case shown in FIG. 4B or FIG. 4D). At this time, each partial detector outputs an output value in proportion to the irradiation amount of the detected reflected light RD to each partial detector, and as a result, the first term on the right side and the second term on the right side of Expression (1) The absolute value of the difference indicates the amount of radial tilt, and the sign of the difference indicates the polarity of the radial tilt.

On the other hand, if the tangential error signal Ste is generated as in the equation (2), when there is no tangential tilt, that is, FIG. 4A or FIG.
When the detection reflected light RD is irradiated on the detector 7 as shown in the following expression, the first term on the right side and the second term on the right side of the equation (2) become equal. As a result, the output value of the tangential error signal Ste becomes It becomes "0".

However, when there is a tangential tilt, that is, when the detection reflected light RD is applied to the detector 7 as shown in FIG. 4C or 4D, the right side of the equation (2) The first term is not equal to the second term on the right side (in the case shown in FIG. 4C or FIG. 4D,
The first term on the right side is larger than the second term on the right side. As a result, the output value of the tangential error signal Ste is no longer "0" (it becomes positive in the case shown in FIG. 4C or 4D). At this time, as in the case of the radial tilt, an output value proportional to the irradiation amount of the detected reflected light RD to each of the partial detectors is output from each of the partial detectors. As a result, the first value on the right side of Expression (2) is obtained. The absolute value of the difference between the term and the second term on the right side indicates the amount of tangential tilt, and the sign of the difference indicates the polarity of tangential tilt.

According to the principle described above, according to the present invention,
Since the radial error signal Sre and the tangential error signal Ste indicating the amounts and polarities of the radial tilt and the tangential tilt, respectively, are obtained from the output signal from the detector 7, the radial tilt and the tangential tilt can be obtained without providing a light source dedicated to tilt detection. It becomes possible to detect an initial tilt.

(II) Embodiment Next, an embodiment of the present invention will be specifically described with reference to FIGS.

In the embodiment described below, the present invention detects a tilt in each direction of the optical disk 1 to compensate for a wavefront aberration caused by the tilt, and performs focus servo control by an astigmatism method. This is an embodiment in which the present invention is applied to an information reproducing apparatus that reproduces information recorded above.

FIG. 5 is a block diagram showing an outline of an information reproducing apparatus according to the embodiment. FIG. 6 shows a method of generating a radial error signal Sre and a tangential error signal Ste while simultaneously generating a focus error signal by an astigmatism method. FIG. 9 is a block diagram illustrating a schematic configuration of a signal processing unit described later that also generates a signal.

Further, it is assumed that information to be reproduced is recorded on the optical disc 1 in the embodiment in advance.

As shown in FIG. 5, in addition to the configuration of the optical system S for explaining the principle shown in FIG. 1, the information reproducing apparatus P of the embodiment has a liquid crystal panel 40 for canceling the wavefront aberration, and a recording / reproducing reflection. A cylindrical lens 10 for giving astigmatism to the optical PD, an actuator 11 for focus servo control, a signal processing unit 12 as an error signal generation unit, a focus error signal generation unit, and a detection signal generation unit; It comprises a reproducing unit 13 as means, amplifiers 14, 16 and 18, drivers 15 and 17, a driver 19 as focus servo means, and a tilt driver 45 as compensation means.

Here, the liquid crystal panel 40 is a transmission type liquid crystal panel that gives a phase difference to the light beam B by using a known technique to cancel the generated wavefront aberration.

More specifically, the liquid crystal panel 40 has a structure in which a liquid crystal layer 40c is sandwiched between transparent electrodes 40a and 40b, and the transparent electrode 40a records on the information recording surface 1a due to radial tilt. It is composed of a plurality of partial electrodes having a shape similar to the distribution of the wavefront aberration generated in the irradiation range of the reproduction light beam B1, and the transparent electrode 40a is formed by a drive signal Sdr described later from the driver 15.
The liquid crystal layer 40c corresponding to each of the partial electrodes is driven independently of each other. As a result, a phase difference that cancels the wavefront aberration caused by the radial tilt is generated in the recording / reproducing light beam B1, and the wavefront aberration is canceled.

On the other hand, the transparent electrode 40b is constituted by a plurality of partial electrodes having a shape similar to the distribution of the wavefront aberration generated in the irradiation range of the recording / reproducing light beam B1 on the information recording surface 1a due to the tangential tilt. The liquid crystal layers 40c corresponding to the respective partial electrodes are driven independently of each other by a drive signal Sdt described later from the driver 17. As a result, a phase difference that cancels out the wavefront aberration caused by the tangential tilt is generated in the recording / reproducing light beam B.
1 to cancel the wavefront aberration.

On the other hand, based on the principle described above, the detector 7 includes partial detectors 7a to 7a as shown in FIG.
n.

At this time, as described above, the area of the circular area including the partial detectors 7j, 7k, 7l, and 7m is wider than the area of the irradiation range of the recording / reproducing reflected light PD, and
The detection reflected light RD is formed so as to be narrower than a region surrounded by an inner peripheral boundary line in an annular irradiation range.

An annular region including the partial detectors 7a, 7b, 7c and 7d and the partial detectors 7e, 7f, 7
g and 7h a circular dividing line RL separating the annular region
Is an annular irradiation range of the detection reflected light RD on the detector 7 when neither the radial tilt nor the tangential is generated on the optical disc 1 (see the right of FIG. 2A).
Is formed so as to coincide with the center line.

Further, of the above-described configuration, the optical pickup S of the present invention is formed by the optical system S, the cylindrical lens 10, the liquid crystal panel 40, the actuator 11, and the signal processing unit 12.

Although FIG. 5 shows only the portion according to the present invention, the actual information reproducing apparatus S additionally performs a so-called tracking servo control on the irradiation position of the light beam B. It includes a servo control unit, a CPU for controlling the entire operation of the information reproducing apparatus S, and an input operation unit for inputting necessary information.

Next, the operation of the information reproducing apparatus P will be described.

The light receiving signals Sp outputted from the respective partial detectors included in the detector 7 by the operation of the optical system S shown in FIG. 1 (in FIG. 5, actually 12 light receiving signals Sp are collected. The light receiving signal Sp is input to the signal processing unit 12.

The signal processing section 12 generates the radial error signal Sre and the tangential error signal Ste by the processing described below based on the above-described principle, and outputs them to the amplifier 14 or 16 and the tilt driver 45, An RF signal Srf corresponding to the information to be reproduced recorded on 1 is generated by a process described later and output to the reproducing unit 13, and a focus error signal Sfe based on the astigmatism method is generated by a process described later. And outputs it to the amplifier 18.

As a result, the reproducing section 13 outputs the RF signal Srf
, A reproduction signal Spu corresponding to the information recorded on the optical disc 1 is generated and output to an external speaker or display (not shown).

The amplifier 18 amplifies the input focus error signal Sfe at a predetermined amplification factor, generates an amplified error signal Saf, and outputs it to the driver 19.

The driver 19 generates a drive signal Sdf for driving the actuator 11 to perform focus servo control based on the amplified error signal Saf, and outputs the drive signal Sdf to the actuator 11.

As a result, the actuator 11 drives the objective lens 2 in a direction parallel to the optical axis of the recording / reproducing light beam B1 (indicated by a dashed line in FIG. 5) based on the driving signal Sdf, and outputs a focus error signal. Focus servo control is performed so that Sfe becomes zero level.

On the other hand, the amplifier 14 amplifies the input radial error signal Sre at a predetermined amplification rate, generates an amplified error signal Sar, and outputs the amplified error signal Sar to the driver 15.

Then, based on the amplified error signal Sar, the driver 15 drives the transparent electrode 40a to cancel the wavefront aberration caused by the radial tilt having the amount and polarity indicated by the radial error signal Sre. Sdr is generated and output to the transparent electrode 40a.

The amplifier 16 amplifies the input tangential error signal Ste at a predetermined amplification rate, generates an amplified error signal Sat, and outputs it to the driver 17.

The driver 17 drives the transparent electrode 40b based on the amplified error signal Sat to cancel the wavefront aberration caused by the tangential tilt having the amount and polarity indicated by the tangential error signal Ste. A drive signal Sdt is generated, and the transparent electrode 40 is generated.
b.

As a result, the liquid crystal layer 40c outputs the drive signal S
The drive voltage applied by the transparent electrode 40a to which dr is applied and the drive voltage applied by the transparent electrode 40b to which the drive signal Sdt is applied, respectively, causes a radial error signal Sre and a tangential error signal Ste for the passing light beam B. A phase difference for canceling the wavefront aberration generated due to the indicated tilt is provided.

At this time, in the liquid crystal panel 40, the driving voltage is applied to the liquid crystal layer 40c by the transparent electrodes 40a and 40b.
, Thereby changing the orientation of the liquid crystal layer 40c to change the refractive index, thereby giving a necessary phase difference to the light beam B.

Further, based on the generated radial error signal Sre and tangential error signal Ste, the tilt driver 45 controls the optical pickup so that each of the radial error signal Sre and the tangential error signal Ste becomes zero level. The entire PU is tilted in a direction to cancel the tilt that has occurred, thereby removing the tilt itself.

Next, the detailed configuration and operation of the signal processing section 12 will be described with reference to FIG.

As shown in FIG. 6, the signal processing section 12 includes adders 20 to 34 and subtracters 35 to 37.

At this time, the light receiving signal Sp from the partial detector 7j and the partial detector 71 are supplied to the adder 20.
The partial detector 7j and the partial detector 7l are connected to the adder 20 so that the light receiving signal Sp from the first detector is input.

The partial detector 7k and the partial detector 7m are supplied to the adder 21 so that the light receiving signal Sp from the partial detector 7k and the light receiving signal Sp from the partial detector 7m are input. It is connected to the.

Further, the partial detector 7e and the partial detector 7f are supplied to the adder 22 such that the light receiving signal Sp from the partial detector 7e and the light receiving signal Sp from the partial detector 7f are input. It is connected to the.

Next, the partial detector 7g and the partial detector 7h are added to the adder 23 so that the light receiving signal Sp from the partial detector 7g and the light receiving signal Sp from the partial detector 7h are input. 23.

Further, for the adder 24, the light receiving signal Sp from the partial detector 7a and the partial detector 7b
The partial detector 7a and the partial detector 7b are connected to the adder 24 so that the light receiving signal Sp from the first detector is input.

The partial detector 7c and the partial detector 7d are supplied to the adder 25 so that the light receiving signal Sp from the partial detector 7c and the light receiving signal Sp from the partial detector 7d are input. It is connected to the.

Next, for the adder 26, the adder 20
The adders 20 and 21 are connected to the adder 26 so that the output signal of the adder 21 and the output signal of the adder 21 are input. Accordingly, the adder 26 outputs a signal obtained by adding all the light receiving signals Sp from the respective partial detectors 7j, 7k, 7l, and 7m, that is, information recorded on the optical disc 1 corresponding to the recording / reproducing reflected light PD. RF corresponding to
The signal Srf will be output.

On the other hand, for the subtractor 35, the adder 20
The adders 20 and 21 are connected to the subtractor 35 such that the output signal of the adder 21 is input to the positive terminal and the output signal of the adder 21 is input to the negative terminal. Thus, the subtractor 35 outputs the partial detectors 7k and 7m from the sum signal of the light receiving signals Sp from the partial detectors 7j and 7l.
Signal obtained by subtracting the sum signal of the respective light receiving signals Sp from the light source, ie, the focus error signal S using a known astigmatism method.
fe will be output. After that, focus servo control is performed by the operations of the amplifier 18, the driver 19, and the actuator 11 so that the focus error signal Sfe becomes zero level.

Next, for the adder 27, the adder 22
The adders 22 and 25 are connected to an adder 27 so that the output signal of the adder 25 and the output signal of the adder 25 are input.

Further, the adder 28 is
The adders 23 and 24 are connected to the adder 28 so that the output signal of the adder 24 and the output signal of the adder 24 are input.

Then, the adder 2 is supplied to the subtractor 36.
8 so that the output signal of the adder 8 is input to the positive terminal and the output signal of the adder 27 is input to the negative terminal.
And 27 are connected to a subtractor 36. This allows
From the subtractor 36, a signal obtained by subtracting the sum signal of the respective light receiving signals Sp from the partial detectors 7c, 7d, 7e and 7f from the sum signal of the respective light receiving signals Sp from the partial detectors 7a, 7b, 7g and 7h, The radial error signal Sre based on the above equation (1) is output.

Next, the partial detector 7e and the partial detector 7h are added to the adder 29 so that the light receiving signal Sp from the partial detector 7e and the light receiving signal Sp from the partial detector 7h are input. 29.

Next, the partial detector 7f and the partial detector 7g are added to the adder 30 so that the light receiving signal Sp from the partial detector 7f and the light receiving signal Sp from the partial detector 7g are input. 30.

Further, for the adder 31, the light receiving signal Sp from the partial detector 7c and the partial detector 7b
The partial detector 7c and the partial detector 7b are connected to the adder 31 so that the light receiving signal Sp from the first detector is input.

Further, the partial detector 7a and the partial detector 7d are supplied to the adder 32 such that the light receiving signal Sp from the partial detector 7a and the light receiving signal Sp from the partial detector 7d are input. It is connected to the.

Next, for the adder 33, the adder 29
The adders 29 and 31 are connected to the adder 33 so that the output signal of the adder 31 and the output signal of the adder 31 are input.

The adder 34 is connected to the adder 30.
The adders 30 and 32 are connected to the adder 34 so that the output signal of the adder 32 and the output signal of the adder 32 are input.

Then, for the subtractor 37, the adder 3
4 so that the output signal of the adder 33 is input to the positive terminal and the output signal of the adder 33 is input to the negative terminal.
And 34 are connected to a subtractor 37. This allows
From the subtracter 37, a signal obtained by subtracting the sum signal of the respective light receiving signals Sp from the partial detectors 7c, 7b, 7e and 7h from the sum signal of the respective light receiving signals Sp from the partial detectors 7a, 7d, 7f and 7g, The tangential error signal Ste based on the above equation (2) is output.

Thereafter, based on the radial error signal Sre and the tangential error signal Ste output respectively, the above-mentioned transparent electrodes 40a and 40b are driven to compensate for the wavefront aberration caused by the tilt in each direction, and ,
The tilt itself generated by the tilt driver 45 is removed.

As described above, according to the tilt detection operation in the information reproducing apparatus S of the embodiment, the light beam emitted from the optical pickup PU that records and reproduces information on the optical disc 1 using the light beam B B is separated to obtain a detection light beam B2, and the tilt of the optical disc 1 is detected using the detection light beam B2. Therefore, the tilt can be detected without using another light beam light source dedicated to the tilt detection. .

Further, since the recording / reproducing light beam B1 and the detection light beam B2 are used separately, the reflected light of the recording / reproducing light beam B1 caused by detecting a tilt using a part of the recording / reproducing light beam B1. Loss can be prevented.

Further, even when no information is recorded on the optical disc 1, the detected reflected light RD can be obtained, so that the tilt can be accurately detected even on an unrecorded recording optical disc.

Further, since the recording / reproducing light beam B1 and the detection light beam B2 are separated by using the objective lens 2 for condensing the recording / reproducing light beam B1 on the information recording surface 1a, the configuration of the optical pickup PU is simplified. In addition, the tilt of the optical disc 1 can be detected.

Furthermore, since the annular detection reflected light RD is received as it is and the radial error signal Sre or the tangential error signal Ste is generated, the tilt of the optical disc 1 in all directions can be detected with a simple configuration. .

Further, since the recording / reproducing reflected light PD and the detected reflected light RD are received by the detector 7, the information recording / reproducing partial detectors 7j, 7k, 7l are provided on one substrate.
And 7 m and partial detectors 7 a to 7 h for tilt detection
Can be integrated, and these can be miniaturized.

The detector 7 is divided into partial detectors 7e to 7h and 7a by a dividing line parallel to the radial direction and a dividing line parallel to the tangential direction.
7 to 7d, the tilt can be reliably detected corresponding to the direction of the tilt to be detected.

Further, a difference signal between the sum signal of the light receiving signals Sp output from the partial detectors 7a, 7b, 7g and 7h and the sum signal of the light receiving signals Sp output from the partial detectors 7e, 7f, 7c and 7d respectively. Is output as the radial error signal Sre indicating the tilt in the radial direction, so that the radial error signal Sre can be accurately generated.

The difference signal between the sum signal of the received light signals Sp output from the partial detectors 7a, 7d, 7f and 7g and the sum signal of the received light signals Sp output from the partial detectors 7b, 7c, 7e and 7h respectively. Is output as the tangential error signal Ste indicating the tilt in the tangential direction, so that the tangential error signal Ste can be accurately generated.

Further, since both the radial error signal Sre and the tangential error signal Ste can be simultaneously generated by the same detector 7, it is possible to generate the radial error signal Sre and the tangential error signal Ste with a simple configuration. it can.

Further, since the element for collecting the detection reflected light RD is constituted by the polarization hologram element 9, the detection reflection light RD can be collected with a simple configuration.

Further, the focus error signal Sfe and the reproduction signal Spu together with the error signal indicating the tilt of the optical disc 1 are provided.
Can also be generated.

Furthermore, the tilt of the optical disc 1 can be accurately detected and compensated for, and the information can be reproduced accurately.

(III) Modified Embodiment Next, a modified embodiment of the present invention will be described with reference to FIG.

In FIG. 7, the same components as those in FIG. 5 are denoted by the same reference numerals, and detailed description is omitted.

Although the above embodiment has been described in connection with the case where the present invention is applied to the information reproducing apparatus S, the present invention is also applicable to the case where address information or the like recorded in advance on the optical disc 1 is used. The present invention can also be applied to an information recording device for detecting recording control information and recording information on the optical disc 1 based on the detected recording control information.

That is, as shown in FIG. 7, the optical system S shown in FIG. 1, the cylindrical lens 10, the signal processing unit 12, the reproducing unit 13, the amplifiers 14, 16 and 1 shown in FIG.
8, drivers 15, 17 and 19, tilt driver 4
5. In addition to the liquid crystal panel 40 and the actuator 11, recording control is performed based on a reproduction signal Spu output from the reproduction section 13 (this reproduction signal Spu includes the above-described recording control information). CP as recording means
A modulation signal Srr for modulating an externally input recording signal Sr to be recorded based on U42 and a control signal Sc from the CPU 42, and setting the output value of the laser diode 8 to a value corresponding to the recording signal Sr. Recording device R comprising: an encoder 41 as recording means for generating the
The present invention can also be applied to

In this case, the output value of the laser diode 8 (ie, the intensity of the light beam B) is intensity-modulated based on the modulation signal Srr, and the intensity-modulated light beam B is included in the recording control information. By irradiating a position corresponding to the address information of the optical disk 1, an information pit having a shape corresponding to the modulation signal Srr is formed at the irradiated position, and the recording signal Sr is recorded on the optical disk 1.

According to the operation of the information recording apparatus R, the wavefront aberration caused by the tilt of the optical disc 1 in each direction is accurately compensated, and the light receiving signal Sp including the recording control information is obtained.
Is accurately reproduced, so that information to be recorded accurately can be recorded on the optical disc 1.

Further, in the above-described embodiment and each modified example, the case where the liquid crystal panel 40 is used as a method of compensating the wavefront aberration has been described. In addition, for example, the generated radial error signal Sre and the tangential Even in a method of mechanically tilting the entire optical pickup PU using the error signal Ste and compensating for the tilt in each direction only by using the error signal Ste, the radial error signal Sre and the tangential error signal Ste obtained by the present invention are used. By using this, wavefront aberration can be easily and reliably compensated.

[0133]

As described above, according to the first aspect of the present invention, in an optical pickup for recording and reproducing information on a recording medium using a light beam, the emitted light beam is separated. Since the detection light beam is obtained and the inclination of the recording medium is detected using the detection light beam, the inclination can be detected without using another light beam light source dedicated to the inclination detection.

Therefore, the inclination between the information recording surface and the optical axis of the light beam can be detected with a simple configuration.

Further, since the recording / reproducing light beam and the detection light beam are used separately, loss of the reflected light of the recording / reproducing light beam caused by detecting inclination using a part of the recording / reproducing light beam can be prevented. it can.

Accordingly, it is possible to increase the output level of the light receiving signal generated based on the reflected light of the recording / reproducing light beam.

Further, even when no information is recorded on the recording medium, the detected reflected light can be obtained, so that the inclination of the unrecorded recording medium can be accurately detected.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the effects of the invention described in (1), since the recording / reproducing light beam and the detection light beam are separated by using a condensing means for condensing the recording / reproducing light beam on the information recording surface, the configuration of the optical pickup is simplified. In addition, the inclination of the recording medium can be detected.

According to the invention set forth in claim 3, claim 2 is provided.
In addition to the effects of the invention described in (1), an inclination error signal is generated by receiving the annular detection reflected light as it is, so that inclination in any direction on the recording medium can be detected with a simple configuration.

According to the invention set forth in claim 4, according to claim 3,
In addition to the effects of the invention described in (1), since the detecting light receiving means is detected on the substrate on which the light receiving means is formed, the light receiving means for information recording / reproducing and the detecting light receiving for tilt detection are provided on one substrate. Means can be integrated, and these can be miniaturized.

The detecting light receiving means is divided into an inner detecting light receiving means and an outer detecting light receiving means, and the inner detecting light receiving means is constituted by a plurality of first partial detecting light receiving means.
Since the outside detection light receiving means is constituted by the plurality of second partial detection light receiving means, the inclination can be reliably detected corresponding to the direction of the inclination to be detected.

According to the invention set forth in claim 5, according to claim 4,
In addition to the effects of the invention described in the above, the sum signal of the detected light receiving signal output from the radius second partial detection light receiving means and the detected light receiving signal output from the radius first partial detection light receiving means in the detection light receiving means, respectively, A detection light receiving signal output from each of the second partial detection light receiving means other than the radius second partial detection light receiving means among the second partial detection light receiving means in the detection light receiving means, and a radius first partial detection among the first partial light receiving detection means Since the difference signal between the sum signal and the detected light receiving signal output from the first partial light receiving detecting means other than the light receiving means is output as a tilt error signal indicating the tilt in the radial direction, the tilt error signal in the radial direction can be accurately calculated. Can be generated.

According to the invention set forth in claim 6, according to claim 5,
In addition to the effects of the invention described in the above, the sum signal of the detected light receiving signal output from the tangential second part detecting light receiving means and the detected light receiving signal respectively output from the tangential first part detecting light receiving means in the detecting light receiving means. A detection light receiving signal output from each of the second partial detection light receiving means other than the tangential second partial detection light receiving means among the second partial detection light receiving means in the detection light receiving means, and a tangential first partial detection among the first partial light receiving detection means The difference signal between the detected light reception signal and the sum signal output from the first partial light reception detection means other than the light reception means is output as the inclination error signal indicating the inclination in the tangential direction. Can be generated.

In addition, since the same detection light receiving means can simultaneously generate both a tilt error signal indicating a tilt in the radial direction and a tilt error signal indicating a tilt in the tangential direction, the tilt in the radial direction can be reduced with a simple configuration. A tilt error signal indicating a tangential tilt and a tilt error signal indicating a tangential tilt can be generated.

According to the seventh aspect of the present invention, the third aspect is provided.
In addition to the effects of the invention described in any one of the above-described items, the detected reflected light condensing means can be configured with a simple configuration.

According to the invention described in claim 8, claim 1 is provided.
In addition to the effects of the invention described in any one of the first to seventh aspects, a focus error signal can be generated together with the tilt error signal indicating the tilt of the recording medium.

Therefore, the tilt error signal and the focus error signal can be generated with a simple configuration.

According to the ninth aspect, in the first aspect,
In addition to the effects of the invention described in any one of the above, the detection signal can be generated together with the tilt error signal indicating the tilt of the recording medium.

Accordingly, the tilt error signal and the detection signal can be generated with a simple configuration.

According to the tenth aspect, in addition to the effect of the ninth aspect, it is possible to accurately detect the inclination of the recording medium, compensate for the inclination, and reproduce the information accurately. it can.

According to the eleventh aspect of the present invention. In addition to the effects of the ninth aspect, it is possible to accurately detect the inclination of the recording medium, compensate for the inclination, and record information accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an optical system illustrating the principle of the present invention.

2A and 2B are diagrams showing the principle of the present invention, wherein FIG. 2A is a diagram showing a case where there is no tilt, FIG. 2B is a diagram showing a case where there is a tilt in one direction, and FIG. FIG. 4 is a diagram illustrating a case where a lens is shifted.

FIG. 3 is a plan view showing a divided shape of a detector.

4A and 4B are diagrams illustrating a tilt in each direction and a light receiving state of the detected reflected light. FIG. 4A is a diagram illustrating a light receiving state when there is no tilt, and FIG. 4B is a diagram illustrating only a radial tilt. FIG. 7C is a diagram showing a light receiving state in the case where (c) is a diagram showing a light receiving state when only a tangential tilt exists, and (d) is a diagram showing a case where both a radial tilt and a tangential tilt exist; FIG. 5 is a diagram showing a light receiving state of FIG.

FIG. 5 is a block diagram illustrating a schematic configuration of the information reproducing apparatus according to the embodiment.

FIG. 6 is a block diagram illustrating a detailed configuration of a signal processing unit.

FIG. 7 is a block diagram illustrating a schematic configuration of an information recording apparatus according to a modified embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk 1a ... Information recording surface 2 ... Objective lens 2a ... Transmission part 2b ... Condensing part 3 ... Collimator lens 4 ... Deflection beam splitter 5 ... Condensing lens 6 ... λ / 4 plate 7 ... Detectors 7a, 7b, 7c 7d, 7e, 7f, 7g, 7h, 7
j, 7k, 7l, 7m, 7n Partial detector 8 Laser diode 9 Polarization hologram element 10 Cylindrical lens 11 Actuator 12 Signal processing unit 13 Reproduction unit 14, 16, 18 ... Amplifier 15, 17, 19 ... Driver 20, 21, 22, 23, 24, 25, 26, 27, 2
8, 29, 30, 31, 32, 33, 34 adder 35, 36, 37 subtractor 40 liquid crystal panel 40a, 40b transparent electrode 40c liquid crystal layer 41 encoder 42 CPU 45 tilt driver Sdf Sdr, Sdt: drive signal Saf, Sar, Sat: amplification error signal Sp: light reception signal Sfe: focus error signal Sre: radial error signal Ste: tangential error signal Srf: RF signal Spu: reproduction signal Sc: control signal Sr: recording Signal Srr: Modulated signal S: Optical system R: Information recording device P: Information reproducing device PU: Optical pickup PD: Recording / reproducing reflected light RD: Detection reflected light B1: Recording / reproducing light beam B2: Detection light beam LR, LT: Straight line Division line RL: Circular division line

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) KA21 KA22

Claims (11)

[Claims] 1. An optical pickup for recording and reproducing information by irradiating an information recording surface of a recording medium with a light beam, comprising: an emitting unit for emitting the light beam; Separation means for separating a recording / reproducing light beam into a detection light beam for detecting an inclination between the information recording surface and an optical axis of the recording / reproducing light beam, and the information of the recording / reproducing light beam. A light receiving unit that generates a light receiving signal based on recording / reproducing reflected light that is reflected light from a recording surface; and indicating the inclination based on detected reflected light that is reflected light of the detection light beam from the information recording surface. An optical pickup comprising: a generation unit configured to generate an inclination error signal. 2. The optical pickup according to claim 1, wherein the separating means focuses a central portion of the cross section of the emitted light beam on the information recording surface as the recording / reproducing light beam, and the cross section. An optical pickup for transmitting the light beam in an annular region other than the central portion as the detection light beam in the optical pickup. 3. The optical pickup according to claim 2, wherein the generation unit includes: a detection reflection light collection unit that collects the annular detection reflection light; and a light reception unit that receives the collected annular detection reflection light. An optical pickup comprising: a detection light receiving unit that generates a detection light reception signal; and an error signal generation unit that generates the tilt error signal based on the generated detection light reception signal. 4. The optical pickup according to claim 3, wherein the detection light receiving means is formed in an annular area surrounding the light receiving means on a substrate on which the light receiving means is formed. The means includes: an inner detection light receiving means formed in an inner area in the annular area corresponding to a width of the annular detection reflected light; and an area in the annular area in which the inner detection light receiving means is formed. Outside detection light-receiving means formed in a region other than the above, wherein the inner detection light-receiving means, the center position of the light-receiving means by one or more dividing lines having a direction corresponding to the direction of the inclination And a plurality of first partial detection light receiving means radially divided around the center, and the outer detection light receiving means is radially divided about the center position by the dividing line. Optical pickup, characterized in that it is composed of a plurality of second partial detection light receiving means is. 5. The optical pickup according to claim 4, wherein the recording medium is a disk-shaped recording medium, and the inclination is a radial inclination of the disk-shaped recording medium and a tangential direction of the disk-shaped recording medium. And a tangential direction dividing line that is the dividing line parallel to the tangential direction and a radial dividing line that is the dividing line parallel to the radial direction. And the first and second partial detection light-receiving means are respectively divided into four first and second partial detection light-receiving means. Further, the error signal generation means is connected to the two second and second partial detection light-receiving means via the radial division line. The detection light receiving signal output from the radius second partial detection light receiving means, which is a partial detection light receiving means, is adjacent to the detection light reception signal via the radial division line and the tangential direction. A sum signal of the detected light reception signals respectively output from the radius first partial detection light receiving means being the two first partial detection light receiving means on the opposite side of the radius second partial detection light receiving means with respect to the secant line; The detected light reception signals respectively output from the two second partial detection light receiving means other than the radius second partial detection light receiving means of the second partial detection light receiving means and the radius 1
Outputting a difference signal between the detected light reception signal and a sum signal output from each of the two first partial light reception detection means other than the partial detection light reception means as the inclination error signal indicating the inclination in the radial direction. An optical pickup that features. 6. The optical pickup according to claim 5, wherein the error signal generating unit is two second partial detection light receiving units adjacent to each other via the tangential direction dividing line. The two first partial detection light receiving units are adjacent to each other via the tangential dividing line and are opposite to the tangential second partial detecting light receiving unit with respect to the radial dividing line. Sum signals of the detected light reception signals respectively output from the tangent first part detection light receiving means, and two second second detection light reception means other than the tangent second part detection light reception means.
The detection light reception signal respectively output from the partial detection light receiving means and the detection light reception respectively output from two first partial light reception detection means of the first partial light reception detection means other than the tangential first partial detection light reception means An optical pickup, wherein a difference signal between the signal and a sum signal is output as the tilt error signal indicating the tilt in the tangential direction. 7. The optical pickup according to claim 3, wherein the detection reflected light condensing means is formed by a polarization hologram element. 8. The optical pickup according to claim 1, wherein a focal position of the recording / reproducing light beam and a position of the information recording surface are determined based on the light receiving signal. An optical pickup further comprising a focus error signal generating means for generating a focus error signal indicating a shift in a direction perpendicular to the optical pickup. 9. The optical pickup according to claim 1, wherein information to be reproduced is recorded on the recording medium, and detection corresponding to the information is performed based on the light receiving signal. An optical pickup further comprising a detection signal generating means for generating a signal. 10. The optical pickup according to claim 9, a focus servo unit that controls the focus position based on the focus error signal, a compensating unit that compensates for the tilt based on the tilt error signal, An information reproducing apparatus, comprising: reproducing means for reproducing the information based on a detection signal. 11. The optical pickup according to claim 9, a focus servo unit that controls the focus position based on the focus error signal, a compensating unit that compensates for the tilt based on the tilt error signal, Reproducing means for reproducing the information based on a detection signal and outputting a reproduced signal; controlling the light beam based on the output reproduced signal and recording information to be recorded on the recording medium; Recording means for recording the recording information in the information recording apparatus.