JP2005174517A - Method and device for recording/reproducing information - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for recording/reproducing information, capable of executing stable power learning without causing the DC fluctuation of a reproducing signal. <P>SOLUTION: When a test signal recorded on a magneto-optical recording medium 101 is reproduced to execute power learning, a reproducing magnetic field is applied to the magneto-optical recording medium 101. When the test signal is recorded on the magneto-optical recording medium 101 is recorded, and the signal is reproduced to execute power learning, test recording is carried out in a state where a pit for executing servo control of the magneto-optical recording medium during the recording of the test signal or a pit area having a pit formed to indicate address information is magnetized in a fixed direction. Thus, the fluctuation of the reproducing signal is prevented, and highly accurate power learning is executed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information recording / reproducing method and apparatus for recording information on a magneto-optical recording medium or reproducing recorded information, and more particularly to a power learning technique for determining optimum recording power or optimum reproducing power.

  In recent years, there has been an increasing demand for higher recording density of magneto-optical recording media, and in order to meet this demand, a technology for reproducing very fine recording marks exceeding the optical resolution has been developed. For example, a magnetic super-resolution reproduction method is known as a method for achieving this by devising a recording medium. In this method, in the magnetic multilayer film, the recording mark is transferred only to the detection area narrower than the spot diameter of the reproducing laser, and in other areas, the signal detection area is substantially masked. Therefore, reproduction exceeding the resolution of the optical system becomes possible. However, in order to improve the reproduction resolution in the magnetic super-resolution reproduction method, it is necessary to narrow a signal detection area that can be effectively used, and thus there is a drawback that the reproduction signal amplitude itself is lowered.

  Therefore, as a method for solving the above problems, for example, a method of enlarging and reproducing a recording mark is proposed instead of narrowing the signal detection area as described in Japanese Patent Laid-Open No. 6-290495. (See Patent Document 1). In the method of this publication, a magneto-optical medium composed of a plurality of magnetic layers is irradiated with a light spot, magnetic domains recorded as perpendicular magnetization are transferred to the reproducing layer, and the domain walls of the magnetic domains transferred to the reproducing layer are moved. Thus, reproduction is performed with a size larger than the magnetic domain of the recording layer.

Next, this domain wall motion detection method will be described. FIG. 6 is a schematic diagram for explaining the operation of the domain wall motion detection type magneto-optical recording medium and the reproducing method thereof. FIG. 6A shows an example of a domain wall motion type magneto-optical recording medium. Recording medium and the first magnetic layer 11 having a small magnetic wall coercivity, a second magnetic layer 12 having a relatively low Curie temperature T _S, and a third magnetic layer 13 having a large wall coercivity exchange It is composed of a combined three-layer film. Arrows 14 in each layer indicate the direction of atomic spin. A domain wall 15 is formed at the boundary between regions where spin directions are opposite to each other.

  When the recording film surface is locally heated using the reproducing laser beam 16, a temperature distribution as shown in FIG. 6B is formed, and the domain wall energy density distribution is shown in FIG. 6C. As shown in FIG. Since the domain wall energy density generally decreases as the temperature rises, the distribution is such that the domain wall energy density is the lowest at the peak temperature position. As a result, a domain wall driving force F is generated which attempts to move the domain wall of the first magnetic layer 11 present at the position X to the high temperature side where the energy density is low.

The medium temperature is lower place than the Curie temperature T _S of the second magnetic layer 12, for each of the magnetic layers are exchange-coupled, even acts wall driving force due to the temperature gradient of the foregoing, the third magnetic layer The domain wall movement does not occur due to the thirteen large domain wall coercive forces. However, in high places than the medium temperature T _S by domain wall temperature gradient exchange for coupling is disconnected, a small movement layer of wall coercivity between the first magnetic layer 11 and the third magnetic layer 13 The domain wall can be moved by the domain wall driving force. Therefore, domain walls domain wall motion occurs to the high temperature side in the moving layer instantaneously upon entering the bond cleavage region beyond the position of the temperature T _S in accordance with the scanning of the recording medium.

Domain walls are formed at intervals corresponding to the signal in the recording film, the magnetic domain wall displacement is generated at the mobile layer every time passing through the position of the temperature T _S in accordance with the scanning of the medium. When the medium is scanned at a constant speed, this domain wall movement occurs at a time interval corresponding to the spatial interval of the recorded domain walls. Therefore, the recording signal can be reproduced by detecting the occurrence of the domain wall motion. The occurrence of the domain wall motion can be detected by using the rotation (Kerr effect) of the polarization plane corresponding to the magnetization direction of the domain wall motion region by the reproducing laser beam.

The signal amplitude is determined by the domain wall moving distance, and does not depend on the recorded distance between domain walls, that is, the domain length. Further, instead of the reproduction spot, since isotherm temperature T _S is to continue to discriminate recording pattern, it can be reproduced independently of the signal from the resolution of the optical system.
Japanese Patent Application Laid-Open No. 6-290496

  Incidentally, in the magneto-optical recording medium of the domain wall motion detection method described in Patent Document 1, the voltage level of the MO signal is determined by the domain wall motion from the front of the reproducing beam spot and the magnetization direction behind the spot. In order to detect the reproduction signal with high accuracy, it is desirable that the magnetization direction behind the spot is stable in a certain direction. However, in reality, a pit for servo control or a pit indicating address information is formed. In some cases, the magnetization direction is reversed by using the generated pit region.

  FIG. 7 shows such a state. FIG. 7A shows a state before reverse magnetization reversal, and FIG. 7B shows a state after reversal. When the backward magnetization is reversed as shown in FIGS. 7 (a) to 7 (b), the envelope 31 of the reproduction signal has a backward magnetization direction shown in FIG. 7 (a) as shown in FIG. 7 (c). On the lower side, in the case of FIG. 7B, the level fluctuates in a DC manner on the upper side.

  If such a DC fluctuation of the playback signal occurs during power learning, the playback signal will vary due to duty shift or jitter deterioration, and the optimum recording power or playback power will be calculated for signal detection. Difficult to do. FIG. 8 shows the recording power dependency when the DC fluctuation of the reproduction signal occurs. As is apparent from FIG. 8, the jitter of the reproduction signal with respect to the recording power is unstable in the region where the DC fluctuation occurs, and it is difficult to accurately calculate the optimum recording power.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an information recording / reproducing method and apparatus capable of performing stable power learning without causing DC fluctuation of a reproduced signal. It is in.

  In order to achieve the above object, the present invention provides a third magnetic layer having a domain wall movable at least on a substrate and a recording magnetic domain, and having a domain wall coercive force larger than that of the first magnetic layer. A magnetic layer and a second magnetic layer disposed between the first magnetic layer and the third magnetic layer and having a Curie temperature lower than that of the first magnetic layer and the third magnetic layer are laminated. In the information recording / reproducing method for recording information using the domain wall motion type magneto-optical recording medium or reproducing the recorded information, when performing power learning by reproducing the test signal recorded on the magneto-optical recording medium, A reproducing magnetic field is applied to the magneto-optical recording medium.

  According to the present invention, there is provided at least a first magnetic layer capable of moving a domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, A domain wall motion magneto-optical recording medium disposed between a first magnetic layer and a third magnetic layer, wherein the first magnetic layer and a second magnetic layer having a Curie temperature lower than that of the third magnetic layer are laminated. In the information recording / reproducing method for recording information using or reproducing the recorded information, when a test signal is recorded on the magneto-optical recording medium and the signal is reproduced to perform power learning, the test signal Test recording is performed in a state in which pits for performing servo control of the magneto-optical recording medium or pits indicating address information are formed at the time of recording in a state of being magnetized in a certain direction.

  According to the present invention, there is provided at least a first magnetic layer capable of moving a domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, A domain wall motion type light in which a first magnetic layer and a second magnetic layer having a Curie temperature lower than that of the first magnetic layer and the third magnetic layer are laminated between the first magnetic layer and the third magnetic layer. In an information recording / reproducing apparatus that records information using a magnetic recording medium or reproduces recorded information, when performing power learning by reproducing a test signal recorded on the magneto-optical recording medium, the magneto-optical recording medium And a means for applying a reproducing magnetic field.

  According to the present invention, there is provided at least a first magnetic layer capable of moving a domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, A domain wall motion magneto-optical recording medium disposed between a first magnetic layer and a third magnetic layer, wherein the first magnetic layer and a second magnetic layer having a Curie temperature lower than that of the third magnetic layer are laminated. In an information recording / reproducing apparatus for recording information using or reproducing recorded information, when a test signal is recorded on the magneto-optical recording medium and the signal is reproduced to perform power learning, the test signal It is characterized in that it has means for performing test recording in a state in which pits for performing servo control of the magneto-optical recording medium or pits indicating address information are formed in a fixed direction during recording.

  According to the present invention, power learning is performed while a reproducing magnetic field is applied during reproduction, or power learning is performed in a state where the pit area is magnetized in a certain direction, so that the reproduction signal does not fluctuate and stable. Power learning can be performed.

  Next, the best mode for carrying out the invention will be described with reference to the drawings. First, the basic principle of the present invention will be described. As described above, when the backward magnetization direction is reversed, the reproduction signal causes DC fluctuation. Therefore, in the case where there is a pit area in which a pit for performing servo control or a pit for performing servo control is present, it is required for stable power learning to stabilize the backward magnetization direction in a certain direction. It is done. As a result of earnest research, the inventors of the present application have found that the following two methods are effective in stabilizing the backward magnetization direction in a certain direction.

  The first method is to apply a reproducing magnetic field, and Japanese Patent Application Laid-Open No. 11-86372 proposes a method of suppressing the movement of the domain wall from the rear end by applying the reproducing magnetic field. By using this method, it is possible to prevent DC fluctuation of the reproduction signal by suppressing the movement of the domain wall from the rear end.

  The second method is to magnetize the pit area in a certain direction. As a result of an experiment using a substrate on which a pit area for forming servo control pits or pits indicating address information is present, if the reproduction signal causes a DC fluctuation, the pit area triggers the DC fluctuation. I found out that Thus, when the pit region is magnetized in a certain direction so that no domain wall exists in the pit region, it has been found that the DC fluctuation of the reproduction signal can be suppressed.

  The present invention can prevent the DC fluctuation of the reproduction signal by applying the reproduction magnetic field or magnetizing the pit area in a certain direction, and performs power learning using these methods. Thus, it is possible to obtain a reproduction signal with higher accuracy as compared with the conventional power learning. Therefore, an embodiment of the present invention will be described. The first method described above will be described as a first embodiment, and the second method will be described as a second embodiment.

(First embodiment)
FIG. 1 is a block diagram showing a first embodiment of a magneto-optical recording / reproducing apparatus according to the present invention. In the first embodiment, power learning is performed while applying a reproducing magnetic field to a recording medium. In the figure, reference numeral 101 denotes a domain wall motion type magneto-optical recording medium, and 102 denotes a spindle motor that rotationally drives the optical recording medium 101. Reference numeral 103 denotes a magnetic field applying device that applies a magnetic field to the magneto-optical recording medium 101, and applies a reproducing magnetic field during power learning in addition to applying a recording magnetic field during information recording.

  Reference numeral 104 denotes a pickup that records or reproduces information by irradiating the magneto-optical recording medium 101 with a recording light beam or a reproducing light beam. A reproduction signal 105 detects a difference between a reproduction signal reproduced from the pickup 104 and a predetermined threshold level 106 as described later, and further determines a reproduction signal level by comparing the obtained difference with the 0 level. It is a level determination circuit.

  A reproduction magnetic field adjustment circuit 107 adjusts the reproduction magnetic field strength based on the determination result of the reproduction signal level determination circuit 105, and a magnetic field application device drive circuit that drives the magnetic field application device 103 according to the output of the reproduction magnetic field adjustment circuit 107. is there. Reference numeral 109 denotes a reproduction magnetic field strength determination circuit that determines the reproduction magnetic field strength based on the output of the reproduction signal level determination circuit 105.

  FIG. 2 is a schematic cross-sectional view showing an example of the layer structure of the domain wall motion type magneto-optical recording medium 101 used in this embodiment. As shown in FIG. 1, at least a dielectric layer 25, a first magnetic layer 21 (reproduction layer), a second magnetic layer 22 (adjustment layer), a third magnetic layer 23 (recording layer), a dielectric layer are formed on a substrate 26. The body layer 24 is sequentially laminated.

In the magneto-optical recording medium 101, when the Curie temperature of the first magnetic layer 21 is T _C1 , the Curie temperature of the second magnetic layer 22 is T _C2 , and the Curie temperature of the third magnetic layer 23 is T _C3. The relationship between the Curie temperatures of the magnetic layers satisfies the conditions of T _C1 > T _C2 and T _C3 > T _C2 . In this embodiment, power learning is performed using this magneto-optical recording medium 101.

  Next, the operation of this embodiment will be described. First, a method for determining the reproducing magnetic field strength will be described. First, a predetermined test recording is performed on the magneto-optical recording medium 101 by applying a modulation recording magnetic field to the magneto-optical recording medium 101 by the magnetic field applying device 103 and irradiating a recording light beam from the pickup 104. Next, a reproduction light beam is irradiated from the pickup 104 to the test recording area, and the reflected light is detected by a photodetector (not shown) in the pickup 104 to reproduce the test recording signal.

  A difference between the obtained reproduction signal and the threshold level 106 is always detected in the reproduction signal level determination circuit 105 (difference from the reproduction signal upper peak level), and it is determined whether the difference is> 0. In this case, when the difference is determined to be> 0, the reproducing magnetic field strength adjusting circuit 107 controls the magnetic field applying device driving circuit 108 to adjust the reproducing magnetic field strength applied from the magnetic field applying device 103. After several adjustments of the reproduction magnetic field strength, if the difference from the constant threshold level 106 is determined to be <0, the magnetic field strength at that time is determined as the reproduction magnetic field strength by the reproduction magnetic field strength determination circuit 109, and power learning is performed. I do.

  FIG. 3 is a diagram for explaining a method for adjusting the reproducing magnetic field intensity. First, as shown in FIG. 3A, when the reproducing magnetic field is not applied, the envelope 61 of the reproducing signal causes DC fluctuation in the medium circumferential direction. When the peak level on the upper side of the envelope 61 of the reproduction signal becomes equal to or higher than the threshold level 106, the difference 63 of the reproduction signal level determination circuit 105 is> 0 as shown in FIG. Here, the threshold level 106 serving as a determination reference is a reference value in the case of detecting a reproducing magnetic field that does not cause DC fluctuation of the reproduction signal as described above. For example, the reproduction signal level at the time of erasure (FIG. 3A). The signal amplitude value (indicated by B in FIG. 3A) is greater than or equal to the value obtained by adding A to

  When the difference 63 of the reproduction signal level determination circuit 105 is determined to be> 0, the reproduction magnetic field intensity adjustment circuit 107 increases the reproduction magnetic field intensity 64 by a certain value ΔHr65 as shown in FIG. Then, when the difference 63 of the reproduction signal level determination circuit 105 becomes> 0 again, the reproduction magnetic field strength 64 is further increased by ΔHr65 as shown in FIG.

  FIG. 4A shows the envelope 61 of the reproduction signal when such an operation is repeated and the difference 63 of the reproduction signal level determination circuit 105 is always determined to be <0. 4B shows the difference 63 of the reproduction signal level determination circuit 105 in that case, and FIG. 4C shows the reproduction magnetic field strength 64 (66Hr = N × ΔHr) in that case.

  As shown in FIG. 4A, the envelope 61 of the reproduction signal is stable without causing DC fluctuation, and the reproduction magnetic field strength 64 at this time is used at the time of power learning. Here, the magnitude Hr66 of the reproducing magnetic field strength 64 is N × ΔHr (N: the number of times the difference 63 of the reproduction signal level determination circuit 105 is> 0), and the smallest reproduction without causing DC fluctuation. The magnetic field strength is set. By applying the reproducing magnetic field strength determined using such a method at the time of reproduction, it becomes possible to perform power learning stably.

  Next, an operation when power learning is performed will be described. First, when determining the optimum recording power, a modulated recording magnetic field is applied from the magnetic field applying device 103 to the magneto-optical recording medium 101, and the predetermined pattern signal is changed while changing the recording power of the recording light beam from the pickup 104 within a certain range. Make a test record. This test recording is performed in a predetermined test area of the magneto-optical recording medium 101.

When the test recording is completed, a reproducing light beam having a certain reproducing power is scanned from the pickup 104 to the test area in a state where the reproducing magnetic field obtained previously is applied from the magnetic field applying device 103 to the magneto-optical recording medium 101. The signal is reproduced and the bER (error rate) of the reproduced signal is measured for each recording power. When the measurement is finished, an error rate threshold value (for example, 5 × 10 ⁻⁴ ) is determined, and a lower limit and an upper limit of recording power satisfying an error rate equal to or lower than this threshold value are obtained. .

  Next, when determining the optimum reproduction power, signal recording of a predetermined pattern is performed on the test area of the magneto-optical recording medium 101 using the obtained optimum recording power. Next, the reproduction signal is reproduced while changing the reproduction power within a certain range while applying the reproduction magnetic field, and the error rate of the reproduction signal is measured for each reproduction power. When the measurement is finished, the error rate threshold is similarly determined, and the lower and upper limits of the reproduction power satisfying the threshold or less are obtained, and the power between them is determined as the optimum reproduction power.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In this embodiment, power learning is performed by magnetizing the pit area in a certain direction. FIG. 5 is a diagram for explaining a method of magnetizing the pit area in a certain direction. Here, as shown in FIG. 5, the magneto-optical recording medium 101 includes a recording area and a pit area in which pits (servo pits, address pits, etc.) are formed in the mirror portion. In FIG. 5, the track adjacent to the recording track has been annealed as a specific example, but it is not particularly limited to the presence or absence of the annealing treatment or the groove shape, and all magneto-optical recording media having pit areas Can be applied to.

  Here, a case where recording is performed by a magnetic field modulation method will be described. The recording magnetic field signal is applied in a DC manner in the pit area as shown in FIG. 5, and the pit area of the magneto-optical recording medium 101 is driven by driving the magnetic field applying device 103 of FIG. Can be magnetized in a certain direction. As a result, there is no domain wall in the pit area, so that the playback signal does not fluctuate in DC triggered by the pit area, and power learning can be performed stably. Here, the recording method is not limited to the recording method as long as the pit region is magnetized in a certain direction. Note that the strength of the magnetic field applied to the pit region is preferably set according to the magnetization characteristics of the recording layer of the magneto-optical recording medium.

  Next, when determining the optimum recording power, a modulated recording magnetic field is applied from the magnetic field applying device 103 to the magneto-optical recording medium 101 as in the first embodiment, and a recording light beam is recorded from the pickup 104. Test recording of a predetermined pattern signal is performed while changing the power within a certain range. However, in this embodiment, the pit area of the magneto-optical recording medium 101 is magnetized in a certain direction as shown in FIG. This test recording is performed in a predetermined test area of the magneto-optical recording medium 101.

When the test recording is completed, a reproduction light beam having a certain reproduction power is scanned from the pickup 104 to the test area to reproduce the signal, and the bER (error rate) of the reproduction signal is measured for each recording power. When the measurement is finished, an error rate threshold value (for example, 5 × 10 ⁻⁴ ) is determined, and a lower limit and an upper limit of recording power satisfying an error rate equal to or lower than this threshold value are obtained. . In the case of signal reproduction, since the pit area is magnetized in a certain direction, it need not be magnetized.

  Next, when determining the optimum reproduction power, signal recording of a predetermined pattern is performed on the test area of the magneto-optical recording medium 101 using the obtained optimum recording power. Next, the recorded signal is reproduced while changing the reproduction power within a certain range, and the error rate of the reproduction signal is measured for each reproduction power. When the measurement is finished, the error rate threshold is similarly determined, and the lower and upper limits of the reproduction power satisfying the threshold or less are obtained, and the power between them is determined as the optimum reproduction power. Also in the case of this signal reproduction, the pit area is magnetized in a certain direction, so it is not necessary to magnetize it.

It is a block diagram which shows the 1st Embodiment of this invention. FIG. 2 is a schematic cross-sectional view showing an example of a layer configuration of a magneto-optical recording medium used in the embodiment of FIG. It is a figure which shows the signal of each part in the case of adjusting the reproduction | regeneration magnetic field of 1st Embodiment. It is a figure which shows the signal of each part after the reproduction | regeneration magnetic field determination of 1st Embodiment. It is a figure explaining the 2nd Embodiment of this invention. It is a schematic diagram explaining a domain wall movement reproduction | regeneration system. It is a figure which shows a mode that the envelope of the reproduction | regeneration signal at the time of reverse magnetization reversal changes DC. It is a figure which shows the recording power dependence of the jitter when a reproduction signal produces DC fluctuation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 21 1st magnetic layer 12, 22 2nd magnetic layer 13, 23 3rd magnetic layer 14 Direction of electron spin 15 Domain wall 16 Beam spot for reproduction | regeneration 17 Direction of movement of domain wall 18 Medium movement direction 24 Dielectric layer DESCRIPTION OF SYMBOLS 25 Dielectric layer 26 Substrate 101 Magneto-optical recording medium 102 Spindle motor 103 Magnetic field application device 104 Pickup 105 Reproduction signal level judgment circuit 106 Threshold level 107 Reproduction magnetic field strength adjustment circuit 108 Magnetic field application device drive circuit 109 Reproduction magnetic field strength determination circuit

Claims (5)

At least a first magnetic layer having a movable domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, and the first magnetic layer Using a domain wall motion magneto-optical recording medium disposed between a third magnetic layer and laminated with the first magnetic layer and a second magnetic layer having a Curie temperature lower than that of the third magnetic layer In an information recording / reproducing method for recording information or reproducing recorded information, when reproducing a test signal recorded on the magneto-optical recording medium and performing power learning, a reproducing magnetic field is applied to the magneto-optical recording medium An information recording / reproducing method. The strength of the reproduction magnetic field is determined by adjusting the difference based on the difference between the reproduction signal level of the signal recorded on the magneto-optical recording medium and a predetermined threshold level, and detecting the magnetic field strength without DC fluctuation of the reproduction signal. The information recording / reproducing method according to claim 1, wherein: At least a first magnetic layer having a movable domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, and the first magnetic layer Information is recorded using a domain wall motion magneto-optical recording medium disposed between the third magnetic layers and laminated with the first magnetic layer and the second magnetic layer having a Curie temperature lower than that of the third magnetic layer. Alternatively, in the information recording / reproducing method for reproducing recorded information, when a test signal is recorded on the magneto-optical recording medium and the signal is reproduced to perform power learning, the magneto-optical recording is performed when the test signal is recorded. An information recording / reproducing method, wherein test recording is performed in a state in which a pit for performing servo control of a medium or a pit area on which address information is formed is magnetized in a certain direction. At least a first magnetic layer having a movable domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, and the first magnetic layer Using a domain wall motion magneto-optical recording medium disposed between a third magnetic layer and laminated with the first magnetic layer and a second magnetic layer having a Curie temperature lower than that of the third magnetic layer In an information recording / reproducing apparatus for recording information or reproducing recorded information, when reproducing a test signal recorded on the magneto-optical recording medium and performing power learning, a reproducing magnetic field is applied to the magneto-optical recording medium An information recording / reproducing apparatus comprising: means. At least a first magnetic layer having a movable domain wall on a substrate, a third magnetic layer holding a recording magnetic domain and having a domain wall coercive force larger than that of the first magnetic layer, and the first magnetic layer Information is recorded using a domain wall motion magneto-optical recording medium disposed between the third magnetic layers and laminated with the first magnetic layer and the second magnetic layer having a Curie temperature lower than that of the third magnetic layer. Alternatively, in the information recording / reproducing apparatus for reproducing recorded information, when a test signal is recorded on the magneto-optical recording medium and the signal is reproduced to perform power learning, the magneto-optical recording is performed when the test signal is recorded. An information recording / reproducing apparatus comprising means for performing test recording in a state in which a pit for performing servo control of a medium or a pit area where address information is formed is magnetized in a certain direction.