JP2000057616A - Optical pickup, information reproducing device and information recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup precisely and instantly grasping a spherical aberration amount and polarity, compensating them and precisely recording/ reproducing information even when the spherical aberration occurring in a reflection beam is changes as a characteristic of a protection layer is changed. SOLUTION: Relating to the optical pickup recording/reproducing the information by irradiating an optical disk 1 having at least the protection layer 1a transparent for the light beam B with a light beam B transmitting through the protection layer 1a, a laser diode 8 emitting the light beam B, a signal processing part 11 generating a spherical error signal Ske showing the spherical aberration occurring in the reflection beam due to the characteristic of the protection layer 1a based on the reflection beam from the optical disk 1 of the light beam B and having the polarity and a liquid crystal panel 9 compensating the spherical aberration based on the generated spherical error signal Ske are provided for it.

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. The invention belongs to the technical field of an optical pickup for recording and reproducing information while compensating for spherical aberration caused by a change in the thickness of a protective layer in the recording medium, and an information reproducing apparatus and an information recording apparatus including the optical pickup.

[0002]

2. Description of the Related Art In recent years, so-called DVDs (conventional CDs (Co
Research and development on an optical information recording medium with an increased recording capacity, as typified by an optical disk having an increased recording capacity about seven times as much as an mpact disk), have been actively conducted.

Here, when information is optically recorded / reproduced on / from the information recording medium having a high recording density, the recording / reproducing light beam is extremely finely focused on the information recording surface of the information recording medium. For this purpose, it is necessary to perform the focusing by using an objective lens having a high NA (aperture ratio).

On the other hand, when a light beam is focused on the information recording surface using such an objective lens, it is necessary to transmit the light beam through a transparent protective layer of the information recording medium. As a result, spherical aberration occurs in the reflected light of the light beam from the information recording surface.

Here, for example, in a conventional CD or the like,
Since the information recording density was not so high and the information pits to be read were not so small, the generated spherical aberration could be neglected. However, in the information recording medium having a high information recording density as described above, the objective lens described above was used. High N
In the case where the thickness of the protective layer is different from the time of the A-formation, the amount of spherical aberration generated when the light beam passes through the protective layer is also not negligible.

Therefore, as a method for compensating for the spherical aberration, for example, a phase difference for compensating the generated spherical aberration by a liquid crystal panel with respect to a light beam before irradiating the information recording medium is given. A method of canceling the spherical aberration by giving in advance or a method of compensating for the spherical aberration generated by controlling the gap between the two lenses by configuring the objective lens using two independent lenses and the like. Was used.

As a method for detecting the spherical aberration, an RF generated based on the reflected light of the light beam is used.
By monitoring the amplitude of the (Radio Frequency) signal, the point where the amplitude becomes maximum is detected as the point where the spherical aberration is compensated, and the voltage applied to the liquid crystal panel or the gap between the lenses is determined. The spherical aberration is compensated by controlling the amplitude to be maximum.

[0008]

However, according to the above-described method of obtaining the maximum value of the amplitude of the RF signal and compensating for the spherical aberration, the RF signal is monitored at every predetermined interval, and the maximum value of the amplitude is monitored. Therefore, there is a problem that the compensation operation cannot be sped up.

The problem is that, for example, when the thickness of the protective layer is different for each portion in one information recording medium due to a manufacturing error, the operation of compensating for the spherical aberration is caused by the movement of the information recording medium. Therefore, there is a case where the speed of the change of the spherical aberration cannot be followed.

[0010] On the other hand, the thickness of the protective layer in one information recording medium is constant in the information recording medium. This leads to a problem that the spherical aberration cannot be compensated quickly.

In the above-described method of detecting spherical aberration from the maximum value of the amplitude of the RF signal, since the signal indicating the spherical aberration has no polarity, the polarity of the spherical aberration correction (for example, in the case of compensation by a liquid crystal panel). Cannot be determined as to whether the voltage value applied to the liquid crystal panel should be increased or decreased in order to compensate for the currently occurring spherical aberration). There is also a problem that quick and accurate compensation control cannot be performed by forming a so-called closed loop such as focus servo control using a focus error signal having a mold curve.

Therefore, the present invention has been made in view of the above-mentioned problems, and the problem is that the characteristics of the protective layer typified by the thickness of the protective layer are limited to those in one information recording medium or Even if the spherical aberration generated in the reflected light changes due to a change between a plurality of information recording media, the amount and polarity of the spherical aberration can be accurately and instantly grasped and compensated, and the recording medium can be accurately corrected. Another object of the present invention is to provide an optical pickup capable of recording and reproducing information on an optical pickup, and an information reproducing apparatus and an information recording apparatus including the optical pickup.

[0013]

In order to solve the above-mentioned problems, the present invention is directed to a recording medium such as an optical disk having at least a protective layer transparent to a light beam such as a laser beam. In an optical pickup that transmits the light beam by passing through the protection layer, an emission unit such as a laser diode that emits the light beam and the protection layer based on reflected light of the light beam from the recording medium. Generating means such as a signal processing unit for generating a spherical error signal having a polarity while exhibiting the spherical aberration occurring in the reflected light due to the characteristic, and the spherical aberration based on the generated spherical error signal. Compensation means such as a liquid crystal panel for compensation.

Therefore, since a spherical error signal indicating the spherical aberration and having the polarity is generated, the amount and the polarity of the spherical aberration generated in the reflected light can be accurately and immediately grasped and compensated. .

According to a second aspect of the present invention, there is provided an optical pickup according to the first aspect, wherein the generating means includes a cylindrical lens or the like for generating astigmatism in the reflected light. An astigmatism generating unit, a light receiving unit such as a detector that receives the reflected light having the astigmatism and generates a light receiving signal, and an error such as a subtractor that generates the spherical error signal based on the light receiving signal. Signal generation means.

Therefore, since the spherical error signal is generated by receiving the reflected light given astigmatism, the amount and polarity of the spherical aberration generated in the reflected light can be accurately and immediately grasped and compensated. can do.

According to a third aspect of the present invention, there is provided an optical pickup according to the second aspect, wherein the light receiving means includes a first detector such as a partial detector occupying a central portion of the light receiving means. The light receiving device is divided into a sub-light receiving device and a second sub-light receiving device such as a partial detector occupying a peripheral portion of the first sub-light receiving device. The irradiation intensity distribution on the light receiving means is configured to have a width corresponding to a change caused by the characteristics of the protective layer.

Therefore, since the first sub-light receiving means has a width corresponding to the change of the illuminance intensity distribution on the light receiving means of the reflected light due to the characteristic of the protective layer, each light receiving signal output from each sub-light receiving means. Are changed in response to changes in spherical aberration associated with changes in the characteristics of the protective layer, and accurately detect the amount and polarity of spherical aberration contained in reflected light based on each of the received light signals. be able to.

According to a fourth aspect of the present invention, there is provided an optical pickup according to the third aspect, wherein the first sub-light receiving means passes through centers of the first sub-light receiving means. And a plurality of first detectors such as partial detectors formed by a plurality of dividing lines having directions corresponding to the irradiation intensity distribution.
It is divided into partial light receiving means, and the second sub light receiving means is divided into a plurality of second partial light receiving means such as partial detectors by each of the dividing lines.

Therefore, the first sub-light receiving means and the second sub-light receiving means are respectively divided into a plurality of first partial light receiving means and a plurality of second partial light receiving means by a dividing line having a shape corresponding to the irradiation intensity distribution. Therefore, each of the light receiving signals output from each of the partial light receiving means changes in accordance with the change in the spherical aberration accompanying the change in the characteristics of the protective layer, and is included in the reflected light based on each of the light receiving signals. It is possible to accurately detect the amount and polarity of the spherical aberration.

According to a fifth aspect of the present invention, there is provided an optical pickup according to the fourth aspect, wherein the error signal generating means includes the light intensity of the first partial light receiving means. The light receiving signals respectively output from the first distribution direction light receiving means, which are the plurality of first partial light receiving means, opposing to the irradiation intensity distribution direction which is the direction corresponding to the distribution, and the irradiation among the second partial light receiving means. A sum signal of the light receiving signals respectively output from the second distribution direction light receiving means, which is a plurality of the second partial light receiving means facing in a direction perpendicular to the intensity distribution direction; The light receiving signals respectively output from the plurality of first partial light receiving units other than the first distribution direction light receiving unit and the plurality of second partial light receiving units other than the second distribution direction light receiving unit among the second partial light receiving units. And outputs a difference signal between the sum signal of a plurality of light receiving signals respectively output from the stage as the spherical error signal.

Therefore, the sum signal of the light receiving signal output from each of the first distribution direction light receiving means and the light receiving signal output from each of the second distribution direction light receiving means, and the first signal of the first partial light receiving means A light receiving signal output from each of the plurality of first partial light receiving means other than the distribution direction light receiving means and a plurality of light receiving signals output from a plurality of second partial light receiving means other than the second distribution direction light receiving means among the respective second partial light receiving means. Since the difference signal from the sum signal of the received light signal and the sum signal is output as a spherical error signal, a spherical error signal that accurately indicates the amount and polarity of the spherical aberration generated in the reflected light can be generated.

According to a sixth aspect of the present invention, in the optical pickup according to any one of the second to fifth aspects, the error signal generating means includes:
A focus error signal based on the astigmatism method is further output based on the light receiving signal.

Therefore, the astigmatism generating means can be used both for generating the spherical error signal and for generating the focus error signal.

According to a seventh aspect of the present invention, there is provided an optical pickup according to the sixth aspect, wherein the error signal generating means is output from each of the first distribution direction light receiving means. Sum signal of the light receiving signal and the light receiving signals respectively output from the plurality of second partial light receiving means other than the second distribution direction light receiving means of the second partial light receiving means; Sum signal of the light receiving signals respectively output from the plurality of first partial light receiving means other than the first distribution direction light receiving means among the light receiving means and the light receiving signals respectively output from the second distribution direction light receiving means. Is output as the focus error signal.

Therefore, the focus error signal can be generated by the light receiving means for generating the spherical error signal.

[0027] In order to solve the above-mentioned problem, an invention according to claim 8 is the optical pickup according to any one of claims 4 to 7, wherein information to be reproduced is recorded on the recording medium. And the error signal generating means is a sum of a sum signal of the light receiving signals respectively output from the first partial light receiving means and a sum signal of the light receiving signals respectively output from the second partial light receiving means. The signal is further output as a detection signal corresponding to the information.

Therefore, a detection signal corresponding to the information recorded by the light receiving means for generating the spherical error signal can also be generated.

According to a ninth aspect of the present invention, in the optical pickup according to any one of the third to eighth aspects, the shape of the first sub-light receiving means is circular. It is configured as follows.

Therefore, the amount and polarity of the spherical aberration can be detected more accurately in accordance with the beam shape of the light beam and the irradiation intensity distribution.

[0031] In order to solve the above-mentioned problems, a tenth aspect is provided.
According to the invention described in (1), in the optical pickup according to any one of (3) to (8), the shape of the first sub-light receiving unit is rectangular.

Therefore, the first sub-light receiving means and the second sub-light receiving means can be easily formed.

[0033] In order to solve the above-mentioned problems, the present invention is directed to claim 11.
In the invention described in (1), in the optical pickup according to any one of claims 3 to 8, the shape of the first sub-light receiving means is configured to be octagonal.

Accordingly, the spherical aberration can be accurately detected in accordance with the beam shape of the light beam and the irradiation intensity distribution thereof, and the first sub-light receiving means and the second sub-light receiving means can be simply formed. .

In order to solve the above-mentioned problems, a twelfth aspect of the present invention is described.
An optical pickup according to claim 8,
A focus servo unit such as a driver that controls a focal position of the light beam based on the focus error signal; and a reproducing unit such as a reproducing unit that reproduces the information based on the detection signal.

Accordingly, it is possible to accurately compensate for the spherical aberration occurring in the reflected light due to the characteristics of the protective layer and to reproduce the information accurately.

In order to solve the above-mentioned problems, the present invention is directed to claim 13.
An optical pickup according to claim 8,
A focus servo unit such as a driver that controls a focal position of the light beam based on the focus error signal; a reproducing unit such as a reproducing unit that reproduces the information based on the detection signal and outputs a reproduced signal; Recording means such as an encoder for controlling the light beam based on the output reproduction signal and recording information to be recorded on the recording medium and recording the recording information on the information recording surface.

Therefore, it is possible to accurately compensate for the spherical aberration generated in the reflected light due to the characteristics of the protective layer and to record information accurately.

[0039]

Next, a preferred embodiment of the present invention will be described.

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

The thickness or refractive index of a protective layer (a protective layer that is transparent to a light beam for protecting an information recording surface of an optical disk) considered when designing an optical pickup has an actual optical disk. When the light beam for recording and reproducing information passes through the actual protective layer when the thickness or the refractive index of the protective layer is different from the above, so-called spherical aberration occurs in the light beam. When astigmatism is given to the reflected light, which is reflected from the optical disk as the recording medium and passes through the actual protective layer before and after the reflection and has the spherical aberration, after the reflection, the reflected light is reflected. The shape of the irradiation intensity distribution on the light detector changes the thickness or refractive index of the protective layer (ie,
(The amount and polarity of the spherical aberration generated in the light beam as the light passes through the protective layer).

In the present invention, utilizing this, a spherical error signal indicating the amount and polarity of the spherical aberration is generated, and the generated spherical error signal is used to compensate for the spherical aberration.

Next, the principle of the present invention will be described more specifically.

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 comprises a laser diode 8 as an emitting means for emitting a recording / reproducing light beam B, 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 a polarization plane of the parallel light beam B and a reflection plane of the light beam B reflected from the optical disk 1, respectively. Λ / 4
A plate 45, an objective lens 2 for condensing the light beam B on an information recording surface in the optical disc 1, an optical disc 1 as a recording medium having a protective layer 1a transparent to the light beam B, and light reflected by the optical disc 1. The converging lens 5 condenses the light beam B transmitted through the objective lens 2, the collimator lens 3 and the deflecting beam splitter 4 on the detector 7 by rotating the deflecting surface. A cylindrical lens 6 as generating means and astigmatism generating means for generating astigmatism, and a detector 7 as a light receiving means for receiving the light beam B given astigmatism.

In this configuration, when the light beam B is emitted from the laser diode 8, the deflection beam splitter 4, the collimator lens 3, the λ / 4 plate 45, and the objective lens 2
Is irradiated on the optical disc 1 through the optical disc 1. Then, the irradiated light beam B passes through the protective layer 1a of the optical disk 1, and is reflected again by the information recording surface 1b thereof, and then is again irradiated with the protective layer 1a.
After that, the light is irradiated onto the detector 7 via the objective lens 2, the λ / 4 plate 45, the collimator lens 3, the deflection beam splitter 4, the condenser lens 5, and the cylindrical lens 6.

Next, in the optical system S having such a configuration, when the thickness t of the protective layer 1a is changed (that is, the spherical aberration generated in the light beam B by passing through the protective layer 1a). FIG. 2 shows how the irradiation intensity distribution of the light beam B on the detector 7 changes when the light beam B is in a focused state on the information recording surface 1b when the amount and polarity are changed). Will be explained.

Each of FIGS. 2A to 2E shows that the irradiation intensity distribution of the light beam B on the detector 7 having a square length of 0.16 mm on each side is equal to the thickness of the protective layer 1a. This schematically shows how the thickness t (unit: mm) changes when the thickness of the protective layer 1a is changed from 0.7 mm to 0.5 mm. Here, in each of the figures, it is shown that the closer the black spots are, the higher the irradiation intensity is.

In FIG. 2, parameters other than the thickness t of the protective layer 1a are constant. Further, the thickness t
Is set to 0.6 mm, which is a value used in a general optical disc or the like. When the spherical aberration generated by the optical disc 1 having the ideal value of the thickness t compensates for the spherical aberration. (Ie, the shape of the objective lens 2, the position of the collimator lens 3 (the distance between the objective lens 2 and the collimator lens 3), and the like are set so that the spherical aberration having the reference value can be optimally compensated. ).

As is clear from FIGS. 2A to 2E, when the thickness of the protective layer 1a is changed, the irradiation intensity distribution of the reflected light of the light beam B on the detector 7 has a certain law. Change.

That is, as the thickness t becomes larger than the ideal value (ie, as the amount of spherical aberration generated by the protective layer 1a increases from the reference value), the entire irradiation intensity distribution becomes the upper left direction in FIG. A region in which the irradiation intensity is large extends symmetrically in the lower right direction and extends in the lower left direction and the upper right direction in FIG. 2 near the center of the detector 7 (FIG. 2A).
And (b)).

On the other hand, as the thickness t becomes smaller than the ideal value (that is, as the amount of spherical aberration generated by the protective layer 1a becomes smaller than the reference value), the entire irradiation intensity distribution becomes the upper right direction in FIG. A region having a high irradiation intensity appears in the vicinity of the center of the detector 7 while extending symmetrically in the lower left direction and extending in the lower right direction and the upper left direction in FIG. 2 (see FIGS. 2D and 2E).

When the thickness t is an ideal value, the above-mentioned spread of the irradiation intensity distribution is not seen, and a substantially circular irradiation intensity distribution is obtained (see FIG. 2C). In the present invention, attention is paid to the change in the irradiation intensity distribution, and it is made to correspond to the change in the shape of each irradiation intensity distribution (particularly, the width of the region where the irradiation intensity is increased in the central portion and the direction of the change in the irradiation intensity distribution). , The detector 7 is divided into partial detectors 7a to 7h as shown in FIG. 3, and a spherical error signal indicating a spherical aberration and having a positive or negative polarity is obtained based on an output signal from each of the partial detectors. The spherical aberration is compensated by a servo system including a closed loop based on the error signal.

At this time, the width of the region including the partial detectors 7e to 7h is set so as to be substantially equal to the width of the region where the irradiation intensity at the central portion in the irradiation intensity distribution is high.

More specifically, in the case of the principle of the present invention, in the case shown in FIGS. 2A and 2B, in the detector 7 shown in FIG. 3, the output signal levels of the partial detectors 7e and 7g are changed to the partial detector 7f. And 7h, and the partial detectors 7d and 7b
Is higher than the output signal levels of the partial detectors 7a and 7c.

On the other hand, in the case shown in FIGS. 2D and 2E, in the detector 7 shown in FIG. 3, the output signal levels of the partial detectors 7e and 7g are changed to the partial detector 7f.
And 7h, and the output signal levels of the partial detectors 7d and 7b are lower than the output signal levels of the partial detectors 7a and 7c.

Further, in the case shown in FIG. 2C, the output signals of the partial detectors 7a to 7d become substantially zero, and the output signals of the partial detectors 7e to 7h have substantially the same value.

In the present invention, a spherical error signal Ske (hereinafter, referred to as a spherical error signal) indicating the amount and polarity of spherical aberration is given by the following equation.
It is simply referred to as a spherical error signal Ske. ). That is,

Ske = (“7a” + “7c” + “7f” + “7h”) − (“7b” + “7d” + “7e” + “7g”) (1) Equation (1) ), “7a” is the partial detector 7
"7b" is the output value of the output signal from the partial detector 7c, "7c" is the output value of the output signal from the partial detector 7c, and "7d" 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, and "7e" indicates the output value of the output signal
f "is 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.

If the spherical error signal Ske is generated in this manner, the equation (1) can be obtained in the case shown in FIG. 2A or 2B.
The second term on the right side is larger than the first term on the right side, and as a result, a negative spherical error signal Ske is generated. On the other hand, in the case shown in FIG. 2D or 2E, the first term on the right side is larger than the second term on the right side of equation (1), and as a result, a positive spherical error signal Ske is generated. .

Further, in the case of FIG. 2C, the second term on the right side and the first term on the right side of equation (1) become equal, and as a result, a spherical error signal Ske of zero level is generated.

Accordingly, when the thickness t of the protective layer 1a is larger than its ideal value (0.6 mm), a spherical error signal Ske having a negative value is generated, and when the thickness t is smaller than the ideal value. A spherical error signal Ske having a positive value is generated. When the spherical error signal Ske is equal to the ideal value, a spherical error signal Ske at a zero level is generated. Can be determined.

As apparent from FIGS. 2 and 3, the amount of compensation is the same as that in FIG.
Comparing the absolute value of the spherical error signal Ske in the case of FIG. 2B, the difference in the density of each region in the irradiation hardness distribution is smaller in the case of FIG. In the case of (1), the absolute value of the spherical error signal Ske becomes smaller. Furthermore,
When comparing the absolute value of the spherical error signal Ske between the case of FIG. 2D and the case of FIG. 2E, the case of FIG. 2D shows the difference in density of each region in the irradiation hardness distribution. 2D, the absolute value of the spherical error signal Ske is smaller in the case of FIG. 2D.

That is, the absolute value of the spherical error signal Ske is
Since the larger the difference between the actual thickness t of the protective layer 1a and its ideal value is, the larger the difference, the larger the absolute value of the spherical error signal Ske, the larger the necessary compensation amount can be determined.

According to the principle described above, according to the present invention,
The spherical error signal Ske indicating the amount and polarity of the spherical aberration is represented by S like the focus error signal by the so-called astigmatism method.
Since a spherical curve is formed, the use of the spherical error signal Ske makes it possible to quickly and accurately compensate for spherical aberration by a servo control system having a so-called closed loop.

The irradiation intensity distribution of the reflected light of the light beam B given astigmatism on the detector 7 is determined by the protective layer 1a.
The reason for the change as shown in FIG. 2 due to the change in the thickness t of the light beam B is that, in the present invention, the spherical aberration generated in the light beam B by passing through the protective layer 1a (this spherical aberration is caused by the light beam B Has an axially symmetric distribution shape with the axis as the axis of symmetry,
The amount of aberration differs depending on the thickness t. 2), the astigmatism is superimposed by the cylindrical lens 6. If the polarity and the amount of the spherical aberration change due to the change of the thickness t of the protective layer 1a due to this, FIG. A change in the shape of the irradiation intensity distribution corresponding to the thickness t as shown appears.

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

The embodiment described below relates to an information reproducing apparatus for reproducing information recorded on the optical disk 1 while compensating for spherical aberration and performing focus servo control by the astigmatism method according to the present invention. It is an embodiment to which the present invention is applied.

FIG. 4 is a block diagram showing an outline of an information reproducing apparatus according to the embodiment, FIG. 5 is a plan view showing a shape of the detector of the embodiment, and FIG. 6 shows a case where a spherical error signal Ske is generated. FIG. 7 is a block diagram illustrating a schematic configuration of a signal processing unit that also generates a focus error signal and the like by the astigmatism method. FIG. 7 is a diagram illustrating an example of a waveform of the spherical error signal Ske.

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. 4, the information reproducing apparatus P of the embodiment has a liquid crystal panel 9 as a compensating means for spherical aberration compensation in addition to the configuration of the optical system S for explaining the principle shown in FIG. An actuator 10 as a focus servo unit for focus servo control, a signal processing unit 11 as a generation unit and an error signal generation unit, a reproduction unit 12 as a reproduction unit, an amplifier 13, and a driver 14 as a compensation unit. , An amplifier 15 and a driver 16 as focus servo means.

Here, the liquid crystal panel 9 is a transmission type liquid crystal panel that gives a phase difference for compensating spherical aberration to the light beam B by a known technique.

Further, based on the principle described above, the detector 7 includes, as shown in FIG. 5, partial detectors 7a, 7b, 7c and 7d as second sub-light receiving means and second partial light-receiving means, and a first sub-detector. It is divided into partial detectors 7e, 7f, 7g and 7h as light receiving means and first partial light receiving means.

At this time, as described above, the width of the region including the partial detectors 7e to 7h is substantially equal to the width of the region where the irradiation intensity at the center in the irradiation intensity distribution shown in FIG. Is set.

Further, the optical pickup PU of the present invention is formed by the optical system S, the liquid crystal panel 9 and the actuator 10 in the above configuration.

Although FIG. 4 shows only the part according to the present invention, the actual information reproducing apparatus S additionally has a so-called tracking servo control for performing the 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. 4, eight light receiving signals Sp are actually collected. The light receiving signal Sp is input to the signal processing unit 11.

Then, the signal processing unit 11 performs the above-described processing based on the above-described principle to perform the above-described spherical error signal Ske.
Is output to the amplifier 13 and the optical disk 1
An RF signal Srf corresponding to the information to be reproduced recorded above is generated by a process described later and output to the reproducing unit 12, and further, a focus error signal Sfe based on the astigmatism method is generated.
Is generated by a process described later and output to the amplifier 15.

As a result, the reproducing unit 12 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 15 amplifies the input focus error signal Sfe at a predetermined amplification factor, generates an amplified error signal Saf, and outputs it to the driver 16.

The driver 16 generates a drive signal Sdf for driving the actuator 10 to perform focus servo control based on the amplified error signal Saf, and outputs the drive signal Sdf to the actuator 10.

Thus, the actuator 10 drives the objective lens 2 in a direction parallel to the optical axis of the light beam B (indicated by a dashed line in FIG. 4) based on the drive signal Sdf, and the focus error signal Sfe is generated. Focus servo control is performed so that the level becomes zero.

On the other hand, the amplifier 13 amplifies the input spherical error signal Ske at a predetermined amplification factor, and
ak is generated and output to the driver 14.

Then, based on the amplified error signal Sak, the driver 14 generates a drive signal Sdk for driving the liquid crystal panel 9 to compensate for spherical aberration having the amount and polarity indicated by the spherical error signal Ske, Output to the liquid crystal panel 9.

Thus, the liquid crystal panel 9 outputs the drive signal S
Based on dk, a phase difference is given to the passing light beam B so that the spherical error signal Ske becomes zero level, and the generated spherical aberration is compensated.

At this time, the liquid crystal panel 9 outputs the drive signal Sdk.
Is applied to the liquid crystal layer in the liquid crystal panel 9 to change the orientation of the liquid crystal layer and thereby change the refractive index, thereby giving a necessary phase difference to the light beam B. Become.

Next, the detailed configuration and operation of the signal processing section 11 will be described with reference to FIGS.

As shown in FIG. 6, the signal processing section 11 includes adders 20 to 28 and subtracters 29 and 30.

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

The partial detector 7d and the partial detector 7b are added to the adder 21 so that the light receiving signal Sp from the partial detector 7d and the light receiving signal Sp from the partial detector 7b are input. It is connected to the.

Further, the partial detector 7e and the partial detector 7g 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 7g are input. It is connected to the.

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

Further, for the adder 24, the adder 20
The adders 20 and 23 are connected to the adder 24 so that the output signal of the adder 23 and the output signal of the adder 23 are input.

Further, for the adder 25, the adder 21
The adders 21 and 22 are connected to the adder 25 so that the output signal of the adder 22 and the output signal of the adder 22 are input.

Further, the adders 20 and 22 are connected to the adder 26 so that the output signal of the adder 20 and the output signal of the adder 22 are input to the adder 26. .

Further, for the adder 27, the adder 21
The adders 21 and 23 are connected to the adder 27 so that the output signal of the adder 23 and the output signal of the adder 23 are input.

Then, for the adder 28, the adder 2
The adders 24 and 25 are connected to the adder 28 so that the output signal of the adder 4 and the output signal of the adder 25 are input. Thus, the adder 28 outputs a signal obtained by adding all the light receiving signals Sp from the respective partial detectors 7a to 7h, that is, an RF signal Srf corresponding to the information recorded on the optical disc 1.

On the other hand, for the subtractor 29, the adder 24
The adders 24 and 25 are connected to a subtractor 29 so that the output signal of the adder 25 is input to the positive terminal and the output signal of the adder 25 is input to the negative terminal. As a result, a signal obtained by subtracting the sum signal of the respective light receiving signals Sp from the partial detectors 7b, 7d, 7e, and 7g from the subtractor 29 from the sum signal of the respective light receiving signals Sp from the partial detectors 7a, 7c, 7h, and 7f. That is, the spherical error signal Ske based on the above equation (1) is output.

The waveform of the spherical error signal Ske at this time will be described with reference to FIG. 7. As described in the above principle, the thickness t of the protective layer 1a on the optical disc 1
(Change centered on the ideal value of 0.6 mm), a substantially S-shaped spherical error signal Ske is generated. By using the S-shaped spherical error signal Ske, it is possible to quickly and accurately compensate for the spherical aberration by the servo control system having a so-called closed loop as described above.

Incidentally, the spherical error signal Ske shown in FIG.
When the thickness t of the protective layer 1a is different for each portion in one optical disc 1, the entire spherical error signal Ske shown in FIG. Thickness t of protective layer 1a in one optical disc 1
Is constant in the optical disc 1, but when the thickness t itself deviates from the original ideal value, the spherical error signal Ske shown in FIG. Only the signal Ske is always output.

Next, for the subtracter 30, the adder 26
The adders 26 and 27 are connected to the subtractor 30 so that the output signal of the adder 27 is input to the positive terminal and the output signal of the adder 27 is input to the negative terminal. As a result, a signal obtained by subtracting the sum signal of the respective light receiving signals Sp from the partial detectors 7b, 7d, 7h and 7f from the subtractor 30 from the sum signal of the respective light receiving signals Sp from the partial detectors 7a, 7c, 7e and 7g. That is, the focus error signal Sfe using the known astigmatism method is output.
Thereafter, the driver 16 and the actuator 1 described above are used.
By the operation of 0, focus servo control is performed so that the focus error signal Sfe becomes zero level.

As described above, according to the operation of the information reproducing apparatus S of the embodiment, the spherical error signal indicating the spherical aberration contained in the reflected light of the light beam B and having either one of the positive and negative polarities is obtained. Since Ske is generated, the amount and polarity of the spherical aberration can be accurately and immediately grasped and compensated.

The area including the partial detectors 7e, 7f, 7g and 7h is the area where the reflected light of the light beam B is detected.
The illumination intensity distribution above has a width corresponding to a change caused by a change in the thickness t of the protective layer 1a (that is, a width including a portion where the irradiation intensity is high in the central portion in the irradiation range). Further, since each of the partial detectors has a shape corresponding to the change in the irradiation intensity distribution, each of the eight light receiving signals Sp output from each of the partial detectors is applied to the protective layer 1a.
And the amount and polarity of the spherical aberration contained in the reflected light of the light beam B are accurately detected based on the eight received light signals Sp. be able to.

Further, since the spherical error signal Ske is generated by the signal processing section 11 having the above-described configuration, it is possible to generate the spherical error signal Ske which accurately indicates the amount and polarity of the spherical aberration generated in the reflected light. .

Further, the spherical error signal Ske indicating the spherical aberration
Can also generate the focus error signal Sfe and the RF signal Srf.

Further, since the shape of the region formed by the partial detectors 7e to 7h is rectangular, the detector 7 can be easily formed.

Also, the optical disk 1 can accurately compensate for the spherical aberration generated in the reflected light due to the characteristics of the protective layer 1a.
The above information can be accurately reproduced.

The spherical error signal Ske described above includes the inclination of the information recording surface of the optical disk 1 with respect to the optical axis of the light beam B, the intensity of the light beam B in the aperture on the pupil plane of the objective lens 2 and the intensity of the objective lens 2. It has been experimentally confirmed that it is not affected by the deviation in the direction parallel to the information recording surface, but a deviation occurs between the position of the optical axis of the light beam B and the center position of the detector 7. It has been experimentally confirmed that the level of the entire spherical error signal Ske decreases and the zero-cross point also shifts.

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

In FIG. 9, the same components as those in FIG. 4 are denoted by the same reference numerals, and the detailed description is omitted.

First, the divided shape of the detector 7 will be described.
As shown as a detector 7 ′ in FIG. 8A, the shape of the region formed by the partial detectors 7 e ′ to 7 h ′ may be circular.

Also in this case, the region including the partial detectors 7e 'to 7h' corresponds to the change in the illuminance intensity distribution of the reflected light of the light beam B on the detector 7 due to the change in the thickness t of the protective layer 1a. Area (that is, the area including the part where the irradiation intensity is strong at the center in the irradiation range)
It is said.

In this case, the same effects as those of the above-described embodiment can be obtained, and the partial detectors 7e 'to 7e'
Since the shape of the region including h 'is circular, the amount and polarity of spherical aberration can be detected more accurately in accordance with the beam shape of the light beam B and the irradiation intensity distribution.

Further, regarding the divided shape of the detector 7,
As shown in FIG. 8B as a detector 7 ″, the shape of the region formed by the partial detectors 7 e ″ to 7 h ″ may be an octagon.

In this case as well, as in the case of FIG. 8A, the area including the partial detectors 7e ″ to 7h ″ is the thickness of the protective layer 1a of the illuminance intensity distribution on the detector 7 of the reflected light of the light beam B. The width corresponds to a change caused by a change in the height t.

In this case, the same effects as those of the above-described embodiment can be obtained, and the partial detectors 7e ″ to 7e ″ can be obtained.
Since the area including h ″ is octagonal, the light beam B
, The amount and polarity of spherical aberration can be detected more accurately in accordance with the beam shape and the irradiation intensity distribution thereof, and the detector 7 ″ can be easily formed.

Although the above-described embodiment and each of the modifications have been described with reference to the case where the present invention is applied to the information reproducing apparatus S, other than this,
The present invention is applied to an information recording apparatus for detecting recording control information such as address information recorded in advance on an optical disc 1 and recording information on the optical disc 1 based on the detected recording control information. You can also.

That is, as shown in FIG. 9, the optical system S shown in FIG. 1 and the signal processing unit 11, the reproducing unit 12 shown in FIG.
In addition to the amplifiers 13 and 15, the drivers 14 and 16, the liquid crystal panel 9, and the actuator 10, a reproduction signal Spu output from the reproduction unit 12 (this reproduction signal Spu includes the above-described recording control information. CPU 41 as recording means for performing recording control based on
Based on the control signal Sc from 41, a recording signal Sr to be recorded which is input from the outside is modulated, and a modulation signal Srr for generating an output value of the laser diode 8 to a value corresponding to the recording signal Sr is generated. The present invention is also applicable to an information recording device R including an encoder 40 as recording means.

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 device R, the light receiving signal Sp including the recording control information is accurately reproduced by accurately compensating for the spherical aberration. Can be recorded.

Further, in the above-described embodiment and each modified example, the case where the liquid crystal panel 9 is used as a method of compensating for the spherical aberration has been described. In addition to this, for example, two independent lenses may be used as the objective lenses. A method of compensating for the spherical aberration generated by controlling the gap between the two lenses, or by moving the collimator lens 3 in a direction parallel to the optical axis of the light beam B. By applying closed-loop servo control using the spherical error signal Ske obtained by the present invention to the method of compensating for spherical aberration, spherical aberration can be quickly and reliably compensated.

Further, in the above-described embodiments and modified examples, the case where the spherical aberration generated due to the change in the thickness t of the protective layer 1a is detected and compensated is described. When detecting and compensating for spherical aberration caused by variation in the refractive index of the protective layer 1a (variation within one optical disc 1 or variation among a plurality of optical discs 1), variation in the refractive index is detected. The irradiation intensity distribution of the reflected light of the light beam B on the detector 7 at a certain time varies according to the amount and the polarity of the variation according to the case shown in FIG. 2, so that the present invention is applied also in this case. It is possible to detect and compensate for the spherical aberration.

[0123]

As described above, according to the first aspect of the present invention, since a spherical error signal indicating a spherical aberration and having a polarity is generated, the amount of the spherical aberration generated in the reflected light is obtained. And the polarity can be accurately and immediately grasped and compensated for.

Therefore, even if the spherical aberration generated in the reflected light changes due to a change in the characteristics of the protective layer, the amount and polarity of the spherical aberration can be accurately and immediately grasped and compensated, and the recording medium can be used. On the other hand, information can be accurately recorded and reproduced.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in (1), since the reflected light given astigmatism is received and a spherical error signal is generated, the amount and polarity of the spherical aberration generated in the reflected light can be accurately and immediately grasped. This can be compensated for.

According to the invention described in claim 3, according to claim 2
In addition to the effects of the invention described in (1), since the first sub-light receiving means has a width corresponding to the change of the illuminance intensity distribution on the light receiving means of the reflected light caused by the characteristic of the protective layer, the output from each sub-light receiving means Each of the received light signals is changed in accordance with the change in the spherical aberration accompanying the change in the characteristics of the protective layer, and the amount and polarity of the spherical aberration included in the reflected light based on the received light signals Can be accurately detected.

According to the invention set forth in claim 4, according to claim 3,
In addition to the effects of the invention described in the above, the first sub-light receiving means and the second
Since the sub-light receiving means is divided into a plurality of first partial light receiving means and a plurality of second partial light receiving means, respectively, by a dividing line having a shape corresponding to the irradiation intensity distribution, each light received from each partial light receiving means is divided. Each of the signals changes in accordance with the change in the spherical aberration associated with the change in the characteristics of the protective layer, and the amount and polarity of the spherical aberration contained in the reflected light can be accurately detected based on each of the received light signals. can do.

According to the invention set forth in claim 5, according to claim 4
In addition to the effect of the invention described in the above, the sum signal of the light receiving signal output from each of the first distribution direction light receiving means and the light receiving signal output from each of the second distribution direction light receiving means, and the first partial light receiving A plurality of first means other than the first distribution direction light receiving means;
The light receiving signals respectively output from the partial light receiving means and a plurality of second light receiving means other than the second distribution direction light receiving means among the second partial light receiving means.
Since the difference signal between the sum signal of the plurality of light receiving signals output from the partial light receiving means and the sum signal is output as a spherical error signal, a spherical error signal that accurately indicates the amount and polarity of the spherical aberration generated in the reflected light is generated. can do.

According to the invention described in claim 6, according to claim 2
In addition to the effects of the invention described in any one of the above items 5, the astigmatism generating means can be used for both generation of the spherical error signal and generation of the focus error signal, so that the optical pickup itself can be reduced in size and the spherical shape. An error signal and a focus error signal can be generated.

According to the invention of claim 7, according to claim 6,
In addition to the effects of the invention described in the above, the light receiving signal output from each first distribution direction light receiving means and the plurality of second partial light receiving means other than the second distribution direction light receiving means among the second partial light receiving means respectively. A sum signal of the output light receiving signal and a plurality of first partial light receiving means other than the first distribution direction light receiving means among the first partial light receiving means.
Since the difference signal between the sum signal of the light receiving signal output from each of the partial light receiving means and the light receiving signal output from each of the second distribution direction light receiving means is output as a focus error signal,
The focus error signal can also be generated by the light receiving means for generating the spherical error signal.

According to the invention as set forth in claim 8, according to claim 4,
8. In addition to the effects of the invention described in any one of the above items 7, the sum signal of the light receiving signals respectively output from the first partial light receiving means and the sum signal of the light receiving signals respectively output from the second partial light receiving means Is further output as a detection signal, so that a detection signal corresponding to the information recorded by the light receiving means for generating the spherical error signal can also be generated.

According to the ninth aspect, the third aspect is provided.
In addition to the effects of the invention described in any one of the above items 8, the first sub-light receiving means is circular, so that the spherical aberration of the light beam can be more accurately adjusted in accordance with the beam shape and the irradiation intensity distribution thereof. The quantity and polarity can be detected.

According to the tenth aspect of the present invention, in addition to the effects of the third aspect of the present invention,
Since the shape of the first sub light receiving means is rectangular, the first sub light receiving means and the second sub light receiving means can be easily formed.

According to the eleventh aspect of the present invention, in addition to the effects of the invention of any one of the third to eighth aspects,
Since the shape of the first sub-light receiving unit is octagonal, it is possible to accurately detect spherical aberration in accordance with the beam shape of the light beam and its irradiation intensity distribution, and to use the first sub-light receiving unit and the second sub-light receiving unit. The means can be easily formed.

According to the twelfth aspect of the present invention, in addition to the effects of the eighth aspect of the present invention, the spherical aberration generated in the reflected light due to the characteristics of the protective layer is accurately compensated. Information can be accurately reproduced.

According to the thirteenth aspect, in addition to the effects of the eighth aspect, the spherical aberration generated in the reflected light due to the characteristics of the protective layer is accurately compensated. Information can be accurately recorded.

[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.

FIGS. 2A and 2B are diagrams illustrating the principle of the present invention, wherein FIG. 2A is a schematic diagram illustrating an irradiation intensity distribution of a light beam on a detector when the thickness of a protective layer is 0.7 mm, and FIG. FIG. 4 is a schematic diagram showing an irradiation intensity distribution of a light beam on the detector when the thickness of the protective layer is 0.65 mm, and FIG. 4C is a schematic diagram showing a light beam on the detector when the thickness of the protective layer is 0.6 mm. FIG. 3D is a schematic diagram showing the irradiation intensity distribution of the light beam, and FIG. 4D is a schematic diagram showing the irradiation intensity distribution of the light beam on the detector when the thickness of the protective layer is 0.55 mm;
FIG. 4 is a schematic diagram showing an irradiation intensity distribution of a light beam on a detector when the thickness of a protective layer is 0.5 mm.

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

FIG. 4 is a block diagram illustrating a schematic configuration of the information reproducing apparatus according to the embodiment.

FIG. 5 is a plan view showing the shape of the detector of the embodiment.

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

FIG. 7 is a diagram illustrating a waveform example of a spherical error signal indicating a spherical aberration.

FIG. 8 is a plan view showing a modified form of the divided shape of the detector, where (a) is a plan view showing a first modified form,
(B) is a plan view showing a second modification.

FIG. 9 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 ... Protective layer 1b ... Information recording surface 2 ... Objective lens 3 ... Collimator lens 4 ... Deflection beam splitter 5 ... Condensing lens 6 ... Cylindrical lens 7, 7 ', 7 "... Detector 7a, 7b, 7c, 7d , 7e, 7f, 7g, 7h, 7
a ', 7b', 7c ', 7d', 7e ', 7f', 7
g ′, 7h ′, 7a ″, 7b ″, 7c ″, 7d ″, 7
e ", 7f", 7g ", 7h" ... Partial detector 8 ... Laser diode 9 ... Liquid crystal panel 10 ... Actuator 11 ... Signal processing unit 12 ... Reproduction unit 13, 15 ... Amplifier 14, 16 ... Driver 20, 21, 22, 23, 24, 25, 26, 27, 2
8 Adder 29, 30 Subtractor 40 Encoder 41 CPU 45 λ / 4 plate Sdf, Sdk Drive signal Saf, Sak Amplification error signal Sp Light receiving signal Sfe Focus error signal Ske Spherical error signal Srf ... RF signal Spu ... Reproduction signal Sc ... Control signal Sr ... Recording signal Srr ... Modulation signal S ... Optical system R ... Information recording device P ... Information reproduction device PU ... Optical pickup

Claims (13)

[Claims] 1. An optical pickup for irradiating a light beam with a recording medium having at least a protective layer transparent to a light beam and transmitting the light beam through the protective layer, an emitting unit for emitting the light beam, Based on the reflected light of the beam from the recording medium,
Generating means for generating a spherical error signal having a polarity and exhibiting a spherical aberration occurring in the reflected light due to the characteristics of the protective layer; and compensating the spherical aberration based on the generated spherical error signal. An optical pickup, comprising: 2. The optical pickup according to claim 1, wherein the generating unit includes: an astigmatism generating unit configured to generate astigmatism in the reflected light; and receiving the reflected light having the astigmatism; An optical pickup, comprising: light receiving means for generating a light receiving signal; and error signal generating means for generating the spherical error signal based on the light receiving signal. 3. The optical pickup according to claim 2, wherein said light receiving means is a first sub light receiving means occupying a central part of said light receiving means and a second sub light receiving means occupying a peripheral part of said first sub light receiving means. And the first sub-light receiving unit has a width corresponding to a change in the irradiation intensity distribution of the reflected light having the astigmatism on the light receiving unit due to the characteristic of the protective layer. An optical pickup comprising: 4. The optical pickup according to claim 3, wherein the first sub-light receiving means includes a plurality of division lines each passing through the center of the first sub-light receiving means and having a direction corresponding to the irradiation intensity distribution. Divided into a plurality of first partial light receiving means, wherein the second sub light receiving means is provided with a plurality of second
An optical pickup characterized by being divided into partial light receiving means. 5. The optical pickup according to claim 4, wherein the error signal generating unit includes a plurality of the first partial light receiving units that oppose an irradiation intensity distribution direction that is a direction corresponding to the irradiation intensity distribution. The light receiving signal output from the first distribution direction light receiving means, which is the first partial light receiving means, and the plurality of second parts of each of the second partial light receiving means opposing each other in a direction perpendicular to the irradiation intensity distribution direction. Sum signals of the light receiving signals respectively output from the second distribution direction light receiving means as the light receiving means, and a plurality of the first partial light receiving means other than the first distribution direction light receiving means among the first partial light receiving means Sum signal of the light receiving signals respectively output from the plurality of second partial light receiving means other than the second distribution direction light receiving means among the second partial light receiving means. Optical pickup and outputs the difference signal as the spherical error signal. 6. The optical pickup according to claim 2, wherein the error signal generating unit further outputs a focus error signal based on an astigmatism method based on the light receiving signal. An optical pickup that features. 7. The optical pickup according to claim 6, wherein the error signal generating unit is configured to output the light receiving signal output from each of the first distribution direction light receiving units and the second light receiving unit among the second partial light receiving units. A sum signal of the light receiving signals output from the plurality of second partial light receiving units other than the two distribution direction light receiving units, and a plurality of the first partial light receiving units other than the first distribution direction light receiving unit. Outputting, as the focus error signal, a difference signal between the light receiving signal output from each of the first partial light receiving means and the sum signal of the light receiving signal output from each of the second distribution direction light receiving means. Optical pickup. 8. The optical pickup according to claim 4, wherein information to be reproduced is recorded on the recording medium, and the error signal generating unit is configured to receive each of the first partial light beams. Means for outputting a sum signal of the sum signal of the light receiving signals output from the respective means and the sum signal of the light receiving signals output from the respective second partial light receiving means as a detection signal corresponding to the information. An optical pickup that features. 9. The optical pickup according to claim 3, wherein the shape of the first sub-light receiving unit is circular. 10. The optical pickup according to claim 3, wherein the shape of the first sub-light receiving unit is rectangular. 11. The optical pickup according to claim 3, wherein the shape of the first sub-light receiving unit is an octagon. 12. An optical pickup according to claim 8, a focus servo means for controlling a focal position of the light beam based on the focus error signal, and a reproducing means for reproducing the information based on the detection signal. An information reproducing apparatus, comprising: 13. An optical pickup according to claim 8, a focus servo means for controlling a focal position of the light beam based on the focus error signal, and a reproduction signal for reproducing the information based on the detection signal. A recording unit that 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. An information recording device, characterized in that: