JP2011040110A - Optical recording medium initialization method and initialization device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium initialization method and initialization device which achieves reliable focusing operation on a recording medium provided with a recording layer whose reflectance before initialization is low, and properly initializes it. <P>SOLUTION: At the start of initialization, a focal position coarse adjustment light beam is focused on the reference plane of the optical recording medium, to roughly focus the initialization light beam on the recording layer to be initialized to partially initialize the recording layer. The initialization light beam is focused in the partially initialized portion of the recording layer. Accordingly, even the recording layer whose reflectance before initialization is extremely low is reliably focused and initialized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an initialization method and an initialization apparatus for an optical recording medium having a recording layer for recording and reproducing information by irradiation with a laser beam or the like.

  An optical recording medium is attracting attention as a large-capacity and high-density memory, and development of what is called an erasable type that can be rewritten is underway. One of the erasable optical recording media uses a thin film that changes phase between an amorphous state and a crystalline state as a recording layer, and records and erases information by thermal energy by laser light irradiation.

  As a phase change material for the recording layer, an alloy film mainly containing Ge, Sb, Te, In, or the like, for example, a GeSbTe alloy is known. Information is recorded by forming a recording mark by partially amorphizing the recording layer. Information is usually erased by crystallizing the recording mark in many cases. Amorphization is performed by heating the recording layer to the melting point or higher and then cooling it. On the other hand, crystallization is performed by heating the recording layer to a temperature not lower than the crystallization temperature and not higher than the melting point. The recording layer is generally formed by sputtering, but the thin film of the phase change material formed by this sputtering is almost in an amorphous state. Therefore, the recording layer needs to be in a crystalline state in advance before recording information. This process is called initialization.

  In recent years, the amount of information handled has increased with the improvement of the processing capabilities of various information devices. Therefore, a recording medium capable of recording and reproducing at a higher capacity and at a higher speed is demanded. As a means for increasing the capacity and speeding up, the wavelength of the recording / reproducing light beam has been shortened, and a laser beam having a wavelength of about 400 nm has been used. On the other hand, in order to reduce the manufacturing cost, it is required to shorten the time required for initialization. For this purpose, it is necessary to simultaneously initialize a wide area of the recording layer using a light beam of a large beam spot. Therefore, a laser beam having a wavelength of about 810 nm that easily obtains a high output is used as the initialization light beam.

  A conventional initialization apparatus that performs the initialization includes an optical head including a semiconductor laser with an initialization wavelength of 810 nm, a semiconductor laser with a wavelength of 400 nm for focus control, and one objective lens. In some cases, a desired region of the recording layer is initialized by moving the optical head in a predetermined direction while irradiating the recording layer of the recording medium with a light beam (see, for example, Patent Document 1).

FIG. 13 is a configuration diagram showing an outline of an optical head in the conventional initialization apparatus described in Patent Document 1. In FIG. In FIG. 13, a light beam 203 emitted from a semiconductor laser 201 with a wavelength of 400 nm and a light beam 204 emitted from a semiconductor laser 202 with a wavelength of 810 nm are reflected by a beam splitter 205 and irradiated onto a recording medium 207 through an objective lens 206. The Here, in a state where the light beam 203 is focused on the recording layer of the recording medium 207, the light beam 204 is also focused on the recording layer of the recording medium 207. The light beam 203 is reflected by the recording layer of the recording medium 207 and enters the photodetector 208 again through the objective lens 206. At this time, the electrical signal generated by the photodetector 208 is output to the focus servo circuit 209. The focus servo circuit 209 focuses the light beams 203 and 204 on the recording layer of the recording medium 207 by driving the actuator 210 based on the electrical signal and adjusting the position of the objective lens.
Japanese Patent Laid-Open No. 2003-22538

  However, in order to further increase the capacity of the recording medium, in addition to the above-mentioned shortening of the wavelength of the recording / reproducing light beam, a plurality of recording layers are provided, and information is recorded / reproduced on each recording layer from one side. Development of multi-layer recording media capable of recording is underway. FIG. 11 is a cross-sectional view schematically showing an example of this multilayer recording medium. In the recording medium 100, a first recording layer 102, a second recording layer 104, a third recording layer 106, and a fourth recording layer 108 are formed on a transparent separation layer 103 on a substrate 101 made of polycarbonate and having a thickness of 1.1 mm. , 105, 107, and a protective film 109 made of an ultraviolet curable resin is formed thereon, and information is recorded on and reproduced from all the recording layers from the protective film 109 side. In this case, since the light beam applied to the first recording layer 102 attenuates when passing through the second recording layer 104, the third recording layer 106, and the fourth recording layer 108, only one recording is performed. Compared with a recording medium having a layer, the amount of reflected light from the recording layer is significantly reduced. Further, with respect to the other recording layers, a high transmittance is required to suppress the attenuation of the light beam, and accordingly, the reflectance must be lowered. In particular, before initialization, that is, when the phase change material of the recording layer is in an amorphous state, the reflectance is low and less than 1%.

  In the conventional initialization apparatus, when trying to initialize such a multilayer recording medium, a sufficient amount of reflected light cannot be obtained from the recording layer, so that focus servo becomes difficult, and initialization can be performed normally. There was a problem that I could not.

  The present invention solves the above-described conventional problems, and is capable of reliably performing a focusing operation on a recording medium having a recording layer with a low reflectance before initialization so that initialization can be performed normally. An object of the present invention is to provide an initialization method and an initialization apparatus for a recording medium.

  In order to achieve the above object, the initialization method of the present invention is an initialization light beam for initializing a recording layer at the start of initialization of at least one recording layer when initializing an optical recording medium. A reference surface different from the at least one recording layer is irradiated with a different focal position coarse adjustment light beam, and the initialization light beam is generated based on a focus error signal generated based on reflected light from the reference surface. The focus is substantially adjusted to the at least one recording layer, and the at least one recording layer is partially initialized, and then generated based on the reflected light from the at least one recording layer of the initialization light beam. The at least one recording layer is initialized while controlling the focal position of the initialization light beam based on the focus error signal.

  As a result, the focusing operation can be reliably performed on the recording medium having a recording layer with a low reflectance before initialization, and the initialization can be normally performed.

  The initialization apparatus according to the present invention includes an initialization optical head, a focal position coarse adjustment optical head provided on the same surface side with respect to the optical recording medium, and an initialization irradiation irradiated from the initialization optical head. A first focus error detector that generates a focus error signal from light reflected from the optical recording medium of the light beam, and the initialization light based on the focus error signal generated by the first focus error detector A first focus position control circuit for controlling a focal position of the beam; a focus error signal is generated from reflected light from the optical recording medium of the focus position coarse adjustment light beam emitted from the focus position coarse adjustment optical head; 2 focus error detectors, and the initialization optical beam based on the focus error signal generated by the second focus error detector. And a second focus position control circuit for controlling the focus position of the focus position coarse adjustment light beam, a moving system for moving the initialization optical head in a predetermined direction, the first focus position control circuit, and the second focus position control circuit. A controller for switching and operating the focal position control circuit. In the initial state, when the second focus position control circuit is operated, the focus position of the initialization light beam and the focus position of the focus position coarse adjustment light beam are set to be a constant distance in the optical axis direction, The distance can be changed to a desired value by an instruction from the controller.

  With this configuration, it is possible to reliably perform a focusing operation on a recording medium having a recording layer with a low reflectance before initialization, and to perform initialization normally.

  Note that only one focus servo circuit is provided, and the controller selects one of the focus error signals generated by the first focus error detector and the second focus error detector and inputs the focus error signal to the focus servo circuit. It is good also as a structure.

  According to the initialization method and the initialization apparatus of the present invention, it is possible to reliably perform a focusing operation on a recording medium having a recording layer with a low reflectance before initialization, and to perform initialization normally. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of an optical recording medium initialization apparatus according to Embodiment 1 of the present invention, and shows a state in which the recording medium 100 having the four recording layers described in FIG. 11 is installed. In FIG. 11, the transparent separation layers 103, 105, and 107 have thicknesses of about 30 μm, 15 μm, and 20 μm, respectively, and the protective film 109 has a thickness of about 35 μm. On the substrate 101 and the transparent separation layers 103, 105, and 107, a guide groove (tracking the laser beam during recording / reproduction is formed by a groove having a depth of about 20 nm, a width of about 0.2 μm, and a pitch of about 0.32 μm. (Not shown) is provided.

  A more detailed structure of the recording medium 100 is shown in FIG. In FIG. 12, a recording layer 102 is a multilayer thin film including a protective layer 110 made of a dielectric material ZnS-SiO2, a phase change layer 111 made of a GeSbTe thin film, a protective layer 112 made of ZnS-SiO2, and a reflective layer 113 made of an Ag alloy thin film. It consists of The recording layer 104 includes a protective layer 114 made of ZnS—SiO 2, a phase change layer 115 made of GeSbTe thin film, a protective layer 116 made of ZnS—SiO 2, a reflective layer 117 made of Ag alloy thin film, and light made of a dielectric material TiO 2. It is composed of a multilayer thin film of the transmittance adjusting layer 118. Similarly to the recording layer 104, the recording layers 106 and 108 are protective layers 119 and 124 made of ZnS-SiO2, phase change layers 120 and 125 made of GeSbTe thin film, protective layers 121 and 126 made of ZnS-SiO2, and Ag, respectively. It is composed of multilayer thin films of reflective layers 122 and 127 made of alloy thin films and light transmittance adjusting layers 123 and 128 made of dielectric material TiO2.

  Each recording layer has a reflectivity of about 0.2% when the phase change layer is in an amorphous state and a phase change layer in a crystalline state with respect to laser light having a wavelength of 405 nm in a form in which the recording medium 100 is completed. The thickness of each thin film is set so that the reflectance is about 1.5%. The reflectance from the surface of the protective film 109 is about 4%.

  In FIG. 1, an initialization apparatus 1 includes a spindle motor 2, an initialization optical head 3, a focal position coarse adjustment optical head 4, a transfer table 5 on which the optical heads 3 and 4 are installed, and the transfer table at a desired position. It comprises moving means 6 for moving, a first focal position control circuit 7, a second focal position control circuit 8, and a controller 9.

  The structure of the initialization optical head 3 is shown in FIG. An initialization light beam 28 emitted from a light source 21 composed of a semiconductor laser having a wavelength of 810 nm is condensed on a recording medium through a collimator lens 22, a beam splitter 23, a quarter wavelength plate 24, and an objective lens 25. The condensed initialization light beam 28 is focused on the recording layer in the recording medium by adjusting the position of the objective lens 25 by the voice coil 26. The spot shape at the focal position of the initialization light beam 28 is shaped as an oval having a length of 100 μm in the radial direction of the recording medium and 1 μm in the circumferential direction. The initialization light beam reflected from the recording layer passes through the objective lens 25 and the quarter-wave plate 24 again, is reflected by the beam splitter 23, enters the focus error detector 27, and is converted into a focus error signal. The focus error signal is output to the first focal position control circuit 7 in FIG.

  Next, the structure of the focal position coarse adjustment optical head 4 is shown in FIG. A focal position coarse adjustment light beam 38 emitted from a light source 31 formed of a semiconductor laser having a wavelength of 405 nm is condensed on a recording medium through a collimator lens 32, a beam splitter 33, a quarter wavelength plate 34, and an objective lens 35. The focused focal position coarse adjustment light beam 38 is focused on the reference plane in the recording medium by adjusting the position of the objective lens 35 by the voice coil 36. The focal position coarse adjustment light beam reflected from the reference surface passes through the objective lens 35 and the quarter wavelength plate 34 again, is reflected by the beam splitter 33, enters the focus error detector 37, and is converted into a focus error signal. . The focus error signal is output to the second focus position control circuit 8 in FIG.

  The controller 9 drives the spindle motor 2 and the moving means 6 and sets the intensity of the initialization light beam 28 and the focus position coarse adjustment light beam 38, in addition to the first focus position control circuit 7 and the second focus position control circuit. 8 is switched to operate to control the entire initialization operation.

  The first focal position control circuit 7 drives the voice coil 26 in FIG. 2 to control the focal position of the initialization light beam. Further, the second focal position control circuit 8 drives the voice coil 26 in FIG. 2 and the voice coil 36 in FIG. 3 at the same time, and the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38. Control while interlocking.

  In the initial state, the distance in the optical axis direction between the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38 is a predetermined value when the second focal position control circuit 8 is operated. The distance can be changed to a desired value by an instruction from the controller.

  FIG. 4 is a flowchart showing an outline of the initialization method in the present embodiment, which will be described with reference to FIG. First, the recording / reproducing apparatus is activated in S1. Specifically, the recording medium 100 is mounted on the spindle motor 2 and rotated. Thereafter, the first recording layer 102 is initialized at S2, the second recording layer 104 is initialized at S3, the third recording layer 106 is initialized at S4, and the fourth recording layer 108 is initialized at S5. Thereafter, the rotation of the spindle motor 2 is stopped in S6, and a series of initialization steps is completed.

  FIG. 5 is a flowchart showing the contents of the first recording layer initialization step S2 in FIG. 4 and will be described with reference to FIGS. First, initial setting is performed in S201. Specifically, the transfer table 5 is moved to the initialization start position, and the distance in the optical axis direction between the focus position of the initialization light beam 28 and the focus position of the focus position coarse adjustment light beam 38 is the surface of the recording medium 100. The positions of the objective lenses 26 and 36 are adjusted so as to be about 100 μm corresponding to the distance between the first recording layer 102 and the first recording layer 102.

  In step S <b> 202, the focus position coarse adjustment light beam 38 is emitted, and the second focus position control circuit 8 is operated to focus the focus position coarse adjustment light beam 38 on the surface of the recording medium 100. Next, in S203, the initialization light beam 28 is emitted, and the second focal position control circuit 8 causes the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38 in the optical axis direction. The first recording layer 102 is partially initialized by interlocking the objective lens 25 with the objective lens 35 so as to keep the distance of about 100 μm.

  Thereafter, the first focus position control circuit 7 is operated in place of the second focus position control circuit 8 in S204, and the focus of the initialization light beam 28 is initialized in S203 of the first recording layer 102. Fit to the place. Then, in S205, it is detected whether or not the initialization light beam 28 is out of focus. If out of focus occurs, the initialization light beam 28 is extinguished in S208, and the initialization operation is terminated. If there is no defocusing, initialization of the recording layer 102 is continued while moving the transfer table 5 in the radial direction of the recording medium 100 at a feed pitch of 50 μm per rotation of the recording medium in S206. Then, in S207, it is determined whether or not the transfer table has reached the initialization end position. If it has not reached the initialization end position, S205 to S207 are repeated. If it is determined that the initialization end position has been reached, the initialization light beam 28 is extinguished in S208, and the initialization operation is terminated.

  The contents of S3, S4, and S5 are to initialize the distance between the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38 in S201 in the optical axis direction with the surface of the recording medium 100, respectively. Except for setting the distance to the recording layers 104, 106, and 108, it is the same as the content of S2 described in FIG.

  Here, Table 1 shows the reflectance and transmittance for light having a wavelength of 810 nm when each recording layer of the recording medium 100 is measured independently, in the case where the phase change layer is in an amorphous state and in the crystalline state.

  In this embodiment, since the recording layers are initialized in order from the first recording layer, all of the recording layers on the protective film side of the recording layer being initialized are in an amorphous state. In S203, the phase change layer in the portion irradiated with the initialization light beam is in a crystalline state. Therefore, Table 2 shows the reflectivity of each recording layer when the initialization light beam is focused in S204 and the reflectivity in the uninitialized state.

  As can be seen from Table 2, in the second recording layer having the lowest reflectivity in the uninitialized state, the reflectivity when the focus of the initialization light beam in S204 is 6 times or more that in the uninitialized state. Thus, focus pull-in becomes easy. Further, as described above, in the multilayer recording medium used in the present embodiment, the reflectance of each recording layer when the phase change layer is in an amorphous state with respect to laser light having a wavelength of 405 nm used for recording and reproduction is about Since this is 0.2%, the conventional method used in the single-layer recording medium (for example, Patent Document 1) is difficult to bring in the focus even if the focus control light beam is used. In the initialization method according to the embodiment, since the reflectance of the initialization light beam when the focus is pulled in is sufficiently high, the focus pull-in becomes easy. Further, in this embodiment, since the focus position light beam is focused on the surface of the recording medium having a high reflectance of about 4% in S202, the focus can be easily pulled.

  In other words, according to the initialization method and the initialization apparatus of the present embodiment, the initialization position is adjusted so that the focus position coarse adjustment light beam is focused on the surface of the recording medium having a high reflectance at the start of initialization. Uninitialized by partially initializing the recording layer by roughly matching the focal position of the beam to the recording layer to be initialized, and drawing the focus of the initialization light beam at the initialized portion of the recording layer In this state, even if the recording layer has a very low reflectance, it is possible to perform the focusing operation reliably and to perform initialization normally.

  As in the first recording layer in the present embodiment, the partial initialization in S203 is performed for a recording layer having a higher reflectance in the uninitialized state than after the initialization with respect to the initialization light beam. In step S204, focus pull-in may be performed in a state where the initialization light beam is emitted with an intensity that does not crystallize the phase change layer, and the subsequent steps may be performed.

  Further, the success or failure of focus pull-in is detected in S204, and when the focus pull-in cannot be performed, the steps after the partial initialization in S203 may be performed again.

(Embodiment 2)
FIG. 6 is a configuration diagram of the optical recording medium initialization apparatus according to Embodiment 2 of the present invention, and shows a state in which the recording medium 100 having the four recording layers described in FIG. 11 is installed. The initialization apparatus 20 in the present embodiment is provided with a focus error signal selection circuit 10 and a focus position control circuit 11 instead of the first focus position control circuit 7 and the second focus position control circuit 8. The configuration is the same as that of the initialization apparatus according to Embodiment 1 described with reference to FIG. 1, and the same components are denoted by the same reference numerals and description thereof is omitted. In FIG. 6, the focus error signal selection circuit 10 selects either the focus error signal output from the focus position coarse adjustment optical head 4 or the focus error signal output from the initialization optical head 3 according to an instruction from the controller 9. Select and output to the focal position control circuit 11. The focus position control circuit 11 drives the voice coil 26 in FIG. 2 and the voice coil 36 in FIG. 3 based on the input focus error signal, and the focus position of the initialization light beam 28 and the focus position coarse adjustment light beam 38. Control the focal position of the.

  The outline of the initialization method in the present embodiment is the same as that of the first embodiment described in FIG. Therefore, only the initialization process of each recording layer will be described. FIG. 7 is a flowchart showing the contents of the first recording layer initialization step S2 in FIG. 4, and will be described with reference to FIGS. 6, 2, and 3. FIG. First, initial setting is performed in S211. Specifically, the transfer table 5 is moved to the initialization start position, and the distance in the optical axis direction between the focus position of the initialization light beam 28 and the focus position of the focus position coarse adjustment light beam 38 is the surface of the recording medium 100. The positions of the objective lenses 25 and 35 are adjusted so as to be about 100 μm corresponding to the distance between the first recording layer 102 and the first recording layer 102.

  Next, in step S212, the focus position coarse adjustment light beam 38 is emitted, the focus error signal selection circuit 10 selects the focus error signal output from the focus position coarse adjustment optical head 4, and the focus error signal is selected based on the focus error signal. The position control circuit 11 is operated so that the focal position coarse adjustment light beam 38 is focused on the surface of the recording medium 100. Next, in S213, the initialization light beam 28 is emitted, and the focal position control circuit 11 sets the distance between the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38 in the optical axis direction. The first recording layer 102 is partially initialized by interlocking the objective lens 26 with the objective lens 36 so as to be maintained at about 100 μm.

  Thereafter, in S214, the focus error signal output from the initialization optical head 3 is selected by the focus error signal selection circuit 10, the focus position control circuit 11 is operated based on the focus error signal, and the initialization light beam is selected. The focus of 28 is adjusted to the location initialized in S213 of the first recording layer 102. Then, in S215, it is detected whether or not the initialization light beam 28 is out of focus. If out of focus occurs, the initialization light beam 28 is extinguished in S218, and the initialization operation is terminated. If there is no defocusing, the initialization of the recording layer 102 is continued while moving the transfer table 5 in the radial direction of the recording medium 100 at a feed pitch of 50 μm per rotation of the recording medium in S216. In step S217, it is determined whether or not the transfer table has reached the initialization end position. If the transfer stage has not reached the initialization end position, steps S215 to S217 are repeated. If it is determined that the initialization end position has been reached, the initialization light beam 28 is extinguished in S218, and the initialization operation is terminated.

  The contents of S3, S4, and S5 initialize the distance in the optical axis direction between the focal position of the initialization light beam 28 in S211 and the focal position of the focal position coarse adjustment light beam 38 with the surface of the recording medium 100, respectively. Except for setting the distance to the recording layers 104, 106, and 108, it is the same as the content of S2 described in FIG.

  With the above configuration, according to the initialization method and the initialization apparatus of the present embodiment, the focus position coarse adjustment light beam is focused on the surface of the recording medium having a high reflectance at the start of initialization, and the initialization light beam In the uninitialized state, the recording layer is partially initialized by roughly matching the focal position with the recording layer to be initialized, and the focus of the initialization light beam is drawn in the initialized portion of the recording layer. Even in the case of a recording layer having a very low reflectance, it is possible to perform the focusing operation reliably and to perform initialization normally.

  Note that, in the case of a recording layer having a higher reflectivity in the uninitialized state than in the initialization light beam as compared to the initialization light beam as in the first recording layer in the present embodiment, the partial initialization in S213 is performed. In step S214, focus pull-in may be performed in a state where the initialization light beam is emitted with an intensity that does not cause the phase change layer to crystallize, and the subsequent steps may be performed.

  Further, the success or failure of focus pull-in may be detected in S214, and if the focus pull-in cannot be performed, the partial initialization and subsequent steps in S213 may be performed again.

(Embodiment 3)
FIG. 8 is a configuration diagram of the optical recording medium initialization apparatus according to Embodiment 3 of the present invention, and shows a state in which the recording medium 100 having the four recording layers described in FIG. 11 is installed. The initialization apparatus 30 in the present embodiment includes the counter 12 that counts the number of times the focal position of the erasing light beam has been moved in the vertical direction, and is the initial stage in the first embodiment described with reference to FIG. The configuration is the same as that of the conversion apparatus, and the same components are denoted by the same reference numerals and description thereof is omitted.

  The outline of the initialization method in the present embodiment is the same as that of the first embodiment described in FIG. Therefore, only the initialization process of each recording layer will be described. FIG. 9 is a flowchart showing the contents of the first recording layer initialization step S2 in FIG. 4 and will be described with reference to FIGS. 8, 2 and 3. FIG. First, initial setting is performed in S221. Specifically, the transfer table 5 is moved to the initialization start position, and the distance in the optical axis direction between the focus position of the initialization light beam 28 and the focus position of the focus position coarse adjustment light beam 38 is the surface of the recording medium 100. The positions of the objective lenses 25 and 35 are adjusted so as to be about 100 μm corresponding to the distance between the first recording layer 102 and the first recording layer 102.

  Next, in step S222, the focus position rough adjustment light beam 38 is emitted, and the second focus position control circuit 8 is operated to focus the focus position rough adjustment light beam 38 on the surface of the recording medium 100. Next, in S223, the initialization light beam 28 is emitted, and the focus of the initialization light beam 28 is added to the movement linked to the focus of the focus position coarse adjustment light beam 38 by the second focus position control circuit 8. The first recording layer 102 is partially initialized while moving a predetermined distance in the vertical direction, for example, ± 5 μm. At this time, the counter 12 counts the number of times the focus of the initialization light beam 28 moves in the vertical direction. When the counter 12 reaches a predetermined number of times, for example, two times, the counter 12 moves up and down the focus of the initialization light beam 28. The movement ends.

  Thereafter, the first focus position control circuit 7 is operated in place of the second focus position control circuit 8 in S224, and the focus of the initialization light beam 28 is initialized in S223 of the first recording layer 102. Fit to the place. Then, in S225, it is detected whether or not the initialization light beam 28 has been out of focus. If out of focus has occurred, the initialization light beam 28 is extinguished in S228, and the initialization operation is terminated. If there is no defocus, the initialization of the recording layer 102 is continued while moving the transfer table 5 in the radial direction of the recording medium 100 at a feed pitch of 50 μm per rotation of the recording medium in S226. In step S227, it is determined whether or not the transfer table has reached the initialization end position. If the transfer stage has not reached the initialization end position, steps S225 to S227 are repeated. If it is determined that the initialization end position has been reached, the initialization light beam 28 is extinguished in S228, and the initialization operation is terminated.

  The contents of S3, S4, and S5 initialize the distance between the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38 in S221 with the surface of the recording medium 100, respectively. Except for setting the distance to the recording layers 104, 106, and 108, it is the same as the content of S2 described in FIG.

  With the above configuration, according to the initialization method and the initialization apparatus of the present embodiment, the focus position coarse adjustment light beam is focused on the surface of the recording medium having a high reflectance at the start of initialization, and the initialization light beam The recording layer is partially initialized by moving it up and down by a predetermined distance from the state where the focal position is substantially aligned with the recording layer to be initialized, and the initialization light beam is focused on the initialized portion of the recording layer. By pulling in, even in a recording layer that has a very low reflectance in an uninitialized state, it is possible to perform the focusing operation reliably and to initialize normally.

  Further, when performing partial initialization of the recording layer at the start of initialization, the focus of the initialization light beam is moved up and down in the vicinity of the recording layer to be initialized, so that the transparent separation layer and the protective layer Even if the recording medium has variations in thickness, it is possible to reliably initialize the recording layer partially. In order to avoid the risk of accidentally initializing another recording layer, the vertical movement distance of the focal point of the initialization light beam should be ½ or less of the thickness of the adjacent transparent separation layer. preferable. The number of times of the vertical movement is not limited to two, but can be set according to the relative speed between the recording medium and the optical head and the vertical movement speed.

  Further, as shown in FIG. 10, a focus error signal selection circuit 10 and a focus position control circuit 11 may be provided instead of the first focus position control circuit 7 and the second focus position control circuit 8. In this case, the focus error signal selection circuit 10 selects either the focus error signal output from the focal position coarse adjustment optical head 4 or the focus error signal output from the initialization optical head 3 according to an instruction from the controller 9. And output to the focal position control circuit 11. The focus position control circuit 11 drives the voice coil 26 in FIG. 2 and the voice coil 36 in FIG. 3 based on the input focus error signal, and the focus position of the initialization light beam 28 and the focus position coarse adjustment light beam 38. Control the focal position of the.

  Note that, in the case of a recording layer that has a higher reflectivity in the uninitialized state than in the initialized light beam with respect to the initialization light beam as in the first recording layer in the present embodiment, the partial initialization in S223 is performed. In step S224, the focus pull-in may be performed in a state where the initialization light beam is emitted with an intensity that does not cause the phase change layer to crystallize, and the subsequent steps may be performed.

  Further, the success or failure of focus pull-in is detected in S224, and when the focus pull-in cannot be performed, the partial initialization and subsequent steps in S223 may be performed again.

(Embodiment 4)
FIG. 14 is a configuration diagram of an optical recording medium initialization apparatus according to Embodiment 4 of the present invention, and shows a state in which the recording medium 100 having the four recording layers described in FIG. 11 is installed. The initialization apparatus 40 in the present embodiment is the same as that in the third embodiment described with reference to FIG. 8 except that the optical head 13 is provided instead of the focal position coarse adjustment optical head 3 and the initialization optical head 4. The configuration is the same as that of the initialization device, and the same components are denoted by the same reference numerals and description thereof is omitted. The structure of the optical head 13 is shown in FIG. The optical head 13 includes light sources 41 and 42 made of semiconductor lasers having respective wavelengths of 810 nm and 405 nm.

  In FIG. 15, the wavelength selective mirror 49 transmits light having the wavelength of the light source 41 and reflects light having the wavelength of the light source 42. The focal position coarse adjustment light beam 55 emitted from the light source 42 passes through the collimator lens 44, the beam splitter 46, and the quarter wavelength plate 48, is reflected by the wavelength selective mirror 49, and is condensed on the recording medium through the objective lens 50. The The focused focal position coarse adjustment light beam 55 is focused on the reference plane in the recording medium by adjusting the position of the objective lens 50 by the voice coil 51. The focal position coarse adjustment light beam reflected from the reference plane again passes through the objective lens 50, is reflected by the wavelength selective mirror 49, passes through the quarter wavelength plate 48, is reflected by the beam splitter 46, and is reflected by the focus error detector 54. Is converted into a focus error signal. The focus error signal is output to the second focus position control circuit 8 in FIG.

  On the other hand, the initialization light beam 56 emitted from the light source 41 passes through the wavelength selective mirror 49 through the optical path correction means 52 made of a liquid crystal element, the collimator lens 43, the beam splitter 45, and the quarter wavelength plate 47, The light is condensed on the recording medium through the objective lens 50. In addition to adjusting the position of the objective lens 50 by the voice coil 51, the condensed initialization light beam 56 is operated in the recording medium by adjusting the focal position by operating the optical path correction means 52. Focus on the recording layer. The spot shape at the focal position of the initialization light beam 56 is shaped as an oval having a length of 100 μm in the radial direction of the recording medium and 1 μm in the circumferential direction. The initialization light beam reflected from the recording layer again passes through the objective lens 50, passes through the wavelength selective mirror 49, passes through the quarter wavelength plate 47, is reflected by the beam splitter 45, and is sent to the focus error detector 53. Incident light is converted into a focus error signal. The focus error signal is output to the first focus position control circuit 7 in FIG.

  The controller 9 drives the spindle motor 2 and the moving means 6, sets the intensity of the initialization light beam 56 and the focus position coarse adjustment light beam 55, and also includes a first focus position control circuit 7 and a second focus position control circuit. 8 is switched to operate to control the entire initialization operation.

  The first focal position control circuit 7 drives the voice coil 51 and the optical path correction means 52 in FIG. 15 to control the focal position of the initialization light beam. The second focus position control circuit 8 operates the voice coil 51 in FIG. 15 to control the focus position of the initialization light beam 56 and the focus position of the focus position coarse adjustment light beam 55 in conjunction with each other.

  In the initial state, the distance between the focus position of the initialization light beam 56 and the focus position of the focus position coarse adjustment light beam 55 in the optical axis direction is a predetermined value when the second focus position control circuit 8 is operated. The optical path correction means 52 can be adjusted according to instructions from the controller, and the distance can be changed to a desired value.

  The outline of the initialization method in the present embodiment is the same as that of the first embodiment described in FIG. Therefore, only the initialization process of each recording layer will be described. FIG. 16 is a flowchart showing the contents of the first recording layer initialization step S2 in FIG. 4, and will be described with reference to FIGS. First, initial setting is performed in S231. Specifically, the transfer table 5 is moved to the initialization start position, and the distance in the optical axis direction between the focus position of the initialization light beam 56 and the focus position of the focus position coarse adjustment light beam 55 is the surface of the recording medium 100. And the optical path correcting means 52 are adjusted so as to be about 100 μm corresponding to the distance between the first recording layer 102 and the first recording layer 102.

  Next, in step S232, the focus position coarse adjustment light beam 55 is emitted, and the second focus position control circuit 8 is operated to focus the focus position coarse adjustment light beam 55 on the surface of the recording medium 100. Next, in S233, the initialization light beam 56 is emitted, and the focus of the initialization light beam 56 is moved in the vertical direction by the optical path correction means 52 in addition to the movement linked to the focus of the focal position coarse adjustment light beam 55. The first recording layer 102 is partially initialized while moving a predetermined distance, for example, ± 5 μm. At this time, the counter 12 counts the number of times the focus of the initialization light beam 56 moves in the vertical direction. When the counter 12 reaches a predetermined number of times, for example, two times, the counter 12 moves up and down the focus of the initialization light beam 56. The movement ends.

  Thereafter, in step S234, the first focus position control circuit 7 is operated instead of the second focus position control circuit 8, and the initialization light beam 56 is focused on the first recording layer 102. Then, in S235, it is detected whether or not the initialization light beam 56 is out of focus. If out of focus occurs, the initialization light beam 56 is extinguished in S238, and the initialization operation is terminated. If there is no out-of-focus condition, initialization of the recording layer 102 is continued while moving the transfer table 5 in the radial direction of the recording medium 100 at a feed pitch of 50 μm per rotation of the recording medium in S236. Then, in S237, it is determined whether or not the transfer table has reached the initialization end position. If it has not reached the initialization end position, S235 to S237 are repeated. If it is determined that the initialization end position has been reached, the initialization light beam 56 is extinguished in S238, and the initialization operation is terminated.

  The contents of S3, S4, and S5 initialize the distance between the focal position of the initialization light beam 28 and the focal position of the focal position coarse adjustment light beam 38 in S231 with the surface of the recording medium 100, respectively. Except for setting the distance to the recording layers 104, 106, and 108, it is the same as the content of S2 described in FIG.

  With the above configuration, according to the initialization method and the initialization apparatus of the present embodiment, the focus position coarse adjustment light beam is focused on the surface of the recording medium having a high reflectance at the start of initialization, and the initialization light beam In the uninitialized state, the recording layer is partially initialized by roughly matching the focal position with the recording layer to be initialized, and the focus of the initialization light beam is drawn in the initialized portion of the recording layer. Even in the case of a recording layer having a very low reflectance, it is possible to perform the focusing operation reliably and to perform initialization normally.

  In order to avoid the risk of accidentally initializing another recording layer, the vertical movement distance of the focal point of the initialization light beam should be ½ or less of the thickness of the adjacent transparent separation layer. preferable. The number of times of the vertical movement is not limited to two, but can be set according to the relative speed between the recording medium and the optical head and the vertical movement speed.

  In the present embodiment, the recording layer portion at the start of initialization is used to ensure that the recording layer is partially initialized even if the recording medium has a variation in the thickness of the transparent separation layer or the protective layer. When performing the initialization, the focus of the initialization light beam is moved up and down in the vicinity of the recording layer to be initialized, but this operation can be omitted. In this case, it is not necessary to provide the counter 12.

  Further, as shown in FIG. 17, a focus error signal selection circuit 10 and a focus position control circuit 11 may be provided instead of the first focus position control circuit 7 and the second focus position control circuit 8. In this case, the focus error signal selection circuit 10 selects either the focus error signal output from the focus error detector 53 or the focus error signal output from the focus error detector 54 according to an instruction from the controller 9, Output to the position control circuit 11. The focal position control circuit 11 operates at least one of the voice coil 51 and the optical path correcting unit 52 in FIG. 15 based on the input focus error signal, and the focal position of the initialization light beam 56 and the focal position coarse adjustment light beam. 55 focal positions are controlled.

  In the above embodiment, the optical path correction means 52 is a liquid crystal element. However, the optical path correction means 52 may be constituted by a lens having a movable mechanism such as a piezoelectric element, and may be installed between the collimator lens 43 and the beam splitter 45. good. Further, an optical path correcting means 52 is provided on a unique optical path of the light beam emitted from the light source 42, and the operation of adjusting the focal position of the light beam emitted from the light source 41 is adjusted by the voice coil 51. The focus position of the light beam emitted from the light source 42 may be adjusted by operating the optical path correction means in addition to the position adjustment of the objective lens 50. In addition, when a dedicated initialization device is used for each recording layer and the reference layer for focusing the focal position coarse adjustment light beam and the recording layer to be initialized are determined for each initialization device, There is no need to provide the optical path correcting means.

  Further, although semiconductor lasers having different wavelengths are used as the light source, the optical paths of the light beams emitted from the light sources 41 and 42 are set at different angles, and the reflected light from the recording medium forms an image at the focus error detector portion. In the case of using another means for separating the reflected light from the recording medium of the light beams emitted from different light sources, for example, different light sources may be used.

  Further, as in the first recording layer in the present embodiment, the partial initialization in S233 is performed on the recording layer having a higher reflectance in the uninitialized state than after the initialization with respect to the initialization light beam. In step S234, the focus pull-in may be performed in a state where the initialization light beam is emitted with an intensity that does not crystallize the phase change layer, and the subsequent steps may be performed.

  Further, the success or failure of focus pull-in may be detected in S234, and if the focus pull-in cannot be performed, the partial initialization and subsequent steps in S233 may be performed again.

  In the first to fourth embodiments, the wavelengths of the focal position coarse adjustment light beam and the initialization light beam and the numerical aperture of the objective lens are the optical characteristics of the recording layer and the thickness of the substrate in the recording medium to be initialized. It can design suitably according to etc. In addition, the number of recording layers of the recording medium to be initialized is not particularly limited, but it is particularly effective for a recording medium having three or more recording layers in which it is difficult to obtain a sufficient amount of reflected light from each recording layer. Demonstrate. The focus servo can be performed by a general method such as a knife edge method or an astigmatism method.

  Furthermore, in the first to fourth embodiments, the reference surface on which the focal position coarse adjustment light beam is focused is the surface of the recording medium. However, a recording layer or a reproduction-only information layer that can obtain a reflected light amount sufficient for focus control, etc. These layers may be used as the reference plane when a recording medium having the above is initialized. In addition, the initialization light beam was emitted after the focus position coarse adjustment light beam was focused. However, the recording layer was emitted in advance at an intensity that does not initialize, and the focus position coarse adjustment light beam was initially focused after the focus adjustment. It is good also as intensity | strength sufficient for conversion.

  When a dedicated initialization device is used for each recording layer, and a reference surface for focusing the light beam for coarse focus position adjustment and a recording layer to be initialized are determined for each initialization device, the initialization layer is used. The distance in the optical axis direction between the focal position of the light beam and the focal position of the focal position coarse adjustment light beam may be fixed to a predetermined value.

  Regarding the area to be initialized of the recording layer, it is preferable that the initialization area of the recording layer to be initialized first includes an initialization area of the recording layer to be initialized later, and has a wider range. As a result, it is possible to avoid the focus servo from being disturbed by the interference light from the boundary portion between the initialized area and the uninitialized area of the recording layer that has been initialized earlier.

  The initialization method of the present invention does not need to be applied to all the recording layers of the recording medium, and is effective when applied to at least one recording layer as necessary.

  An initialization method and an initialization apparatus according to the present invention, when initializing an optical recording medium having a recording layer for recording and reproducing information by irradiation with a laser beam or the like, at the start of initialization of at least one recording layer Irradiating a reference surface different from the at least one recording layer with a focus position coarse adjustment light beam different from the initialization light beam for initializing the recording layer, and generated based on the reflected light from the reference surface. The initializing light beam is substantially focused on the at least one recording layer based on a focus error signal, and the at least one recording layer is partially initialized. While controlling the focal position of the initialization light beam based on a focus error signal generated based on reflected light from at least one recording layer, the at least one The recording layer is initialized, and has an effect that the focusing operation can be reliably performed on the recording layer having a low reflectance before initialization, and the initialization can be performed normally. It is useful for initialization of a multilayer recording medium having It can also be applied to recording media of other shapes such as a card shape.

The block diagram which shows the initialization apparatus in Embodiment 1 of this invention The block diagram which shows the principal part of the initialization apparatus in Embodiment 1 of this invention The block diagram which shows the principal part of the initialization apparatus in Embodiment 1 of this invention The flowchart which shows the outline of the initialization method in Embodiment 1 of this invention. The flowchart which shows the principal part of the initialization method in Embodiment 1 of this invention. The block diagram which shows the initialization apparatus in Embodiment 2 of this invention The flowchart which shows the principal part of the initialization method in Embodiment 2 of this invention. The block diagram which shows the initialization apparatus in Embodiment 3 of this invention The flowchart which shows the principal part of the initialization method in Embodiment 3 of this invention. The block diagram which shows the 2nd form of the initialization apparatus in Embodiment 3 of this invention. Sectional drawing which shows an example of the optical recording medium used as the implementation object of this invention Sectional drawing which shows the detail of an example of the optical recording medium used as the implementation object of this invention Configuration diagram showing a conventional initialization device The block diagram which shows the initialization apparatus in Embodiment 4 of this invention The block diagram which shows the principal part of the initialization apparatus in Embodiment 4 of this invention The flowchart which shows the principal part of the initialization method in Embodiment 4 of this invention. The block diagram which shows the 2nd form of the initialization apparatus in Embodiment 4 of this invention.

Explanation of symbols

1, 20, 30, 40 Initializing device 2 Spindle motor 3 Initializing optical head 4 Focus position coarse adjustment optical head 5 Transfer base 6 Moving means 7, 8, 11 Focus position control circuit 9 Controller 10 Focus error signal selection circuit 12 Counter 13 Optical head 21, 31, 41, 42 Light source 22, 32, 43, 44 Collimator lens 23, 33, 45, 46 Beam splitter 24, 34, 47, 48 1/4 wavelength plate 25, 35, 50 Objective lens 26 , 36, 51 Voice coil 27, 37, 53, 54 Focus error detector 28, 56 Initializing light beam 38, 55 Focus position coarse adjustment light beam 49 Wavelength selective mirror 52 Optical path correcting means 100 Recording medium 102, 104, 106, 108 Recording layer 111, 115, 120, 125 Phase change film

Claims (34)

When initializing the recording layer of the optical recording medium, the optical beam different from the recording layer has a focal position coarse adjustment light beam different from the initialization light beam for initializing the recording layer at the start of the initialization. Irradiating a reference surface in a recording medium and focusing the initialization light beam on the recording layer based on a focus error signal generated based on reflected light from the reference surface, and recording the recording layer After partially initializing the layer, while controlling the focal position of the initialization light beam based on a focus error signal generated based on the reflected light from the recording layer of the initialization light beam A method for initializing an optical recording medium, comprising initializing the optical recording medium. At the start of initialization of the recording layer, the focus of the initialization light beam is roughly aligned with the recording layer, and then moved relative to the recording layer in the vertical direction so that the recording layer is partially The optical recording medium initialization method according to claim 1, wherein the initialization is performed. In an optical recording medium having a plurality of recording layers, relative to the recording layer to be initialized within a range that does not reach the other recording layer after the focus of the initialization light beam is roughly aligned with the recording layer to be initialized 3. The method of initializing an optical recording medium according to claim 2, wherein the optical recording medium is moved vertically. 2. The optical information recording medium initialization method according to claim 1, wherein the reference surface is a light beam irradiation side surface of the optical recording medium. 2. The optical recording medium having a plurality of recording layers, wherein the reference layer is a recording layer having a reflectance higher than that of an uninitialized state with respect to the focal position coarse adjustment light beam of the recording layer to be initialized. 2. An initialization method for the optical recording medium according to 1. The optical recording medium initialization method according to claim 1, wherein the optical recording medium has three or more recording layers. At the start of initialization, the initialization light beam is initially set to an intensity that is insufficient for initialization, and the intensity of the initialization light beam is sufficient to initialize after being roughly aligned with the recording layer to be initialized. The method for initializing an optical recording medium according to claim 1. 2. The optical recording medium having a plurality of recording layers, wherein the recording layer on the front side is initialized after the recording layer on the back side as viewed from the side irradiated with the initialization light beam is initialized. An optical recording medium initialization method. In the optical recording medium having a plurality of recording layers, the initialization area of the recording layer on the back side is wider than the initialization area of the recording layer on the near side when viewed from the side irradiated with the initialization light beam. Item 2. An initialization method for an optical recording medium according to Item 1. 2. The optical recording medium initialization method according to claim 1, wherein wavelengths of the initialization light beam and the focus position coarse adjustment light beam are different. 11. The optical recording medium initialization method according to claim 10, wherein the focal position coarse adjustment light beam has substantially the same wavelength as the light beam for reproducing information from the optical recording medium. The optical recording medium initialization method according to claim 1, wherein the reflectance of the recording layer in an uninitialized state with respect to the initialization light beam is lower than the reflectance after initialization. An initialization optical head and a focal position coarse adjustment optical head provided on the same surface side with respect to the optical recording medium, and an initialization light beam emitted from the initialization optical head from the optical recording medium A first focus error detector that generates a focus error signal from reflected light, and a first focus error control unit that controls a focus position of the initialization light beam based on the focus error signal generated by the first focus error detector. A focus position control circuit; a second focus error detector that generates a focus error signal from reflected light from the optical recording medium of the focus position coarse adjustment light beam emitted from the focus position coarse adjustment optical head; The initialization light beam and the focus position coarse adjustment light beam based on the focus error signal generated by the focus error detector A second focal position control circuit for controlling the focal position of the first, a moving system for moving the initialization optical head in a predetermined direction, and switching between the first focal position control circuit and the second focal position control circuit. A controller to be operated, and in the initial state, the focus position of the initialization light beam and the focus position of the focus position coarse adjustment light beam are at a constant distance in the optical axis direction when the second focus position control circuit is operated. An optical recording medium initialization apparatus, wherein The optical distance according to claim 13, wherein the distance between the focal position of the initialization light beam and the focal position of the focal position coarse adjustment light beam in the optical axis direction can be changed to a desired value by an instruction from a controller. Type recording medium initialization device. The optical recording medium initialization apparatus according to claim 13, further comprising: a drive system that moves the focus of the initialization light beam up and down; and a counter that counts the number of times the focus of the initialization light beam moves up and down. The optical recording medium initialization apparatus according to claim 13, wherein wavelengths of the initialization light beam and the focal position coarse adjustment light beam are different. 14. The optical recording medium initialization apparatus according to claim 13, wherein the focal position coarse adjustment light beam has substantially the same wavelength as a light beam for reproducing information from the optical information recording medium. An initialization optical head and a focal position coarse adjustment optical head provided on the same surface side with respect to the optical recording medium, and an initialization light beam emitted from the initialization optical head from the optical recording medium A first focus error detector for generating a focus error signal from the reflected light, and generating a focus error signal from the reflected light from the optical recording medium of the focus position coarse adjustment light beam emitted from the focus position coarse adjustment optical head A second focus error detector that selects one of a focus error signal generated by the first focus error detector and a focus error signal generated by the second focus error detector Based on the focus error signal selected by the focus error signal selection circuit A focus position control circuit that controls the focus position of the initialization light beam and the focus position coarse adjustment light beam, a moving system that moves the initialization optical head in a predetermined direction, and a signal selection operation of the focus error signal selection circuit In the initial state, when the second focus position control circuit is operated, the focus position of the initialization light beam and the focus position of the focus position coarse adjustment light beam are set to a constant distance in the optical axis direction. An initialization apparatus for an optical recording medium, wherein the initialization apparatus is set. 19. The optical system according to claim 18, wherein the distance between the focal position of the initialization light beam and the focal position of the focal position coarse adjustment light beam in the optical axis direction can be changed to a desired value by an instruction from a controller. Type recording medium initialization device. 19. The optical recording medium initialization apparatus according to claim 18, further comprising: a drive system that moves the focus of the initialization light beam up and down; and a counter that counts the number of times the focus of the initialization light beam moves up and down. The optical recording medium initialization apparatus according to claim 18, wherein wavelengths of the initialization light beam and the focal position coarse adjustment light beam are different. 19. The optical recording medium initialization apparatus according to claim 18, wherein the focal position coarse adjustment light beam has substantially the same wavelength as a light beam for reproducing information from the optical information recording medium. A first light source that irradiates an initialization light beam, a second light source that irradiates a focus position coarse adjustment light beam, the initialization light beam, and the focus position coarse adjustment light beam are collected on an optical information recording medium. An optical head having an objective lens, and a first focus error detector that generates a focus error signal from reflected light from the optical information recording medium of the initialization light beam, and the first focus error detector A first focus position control circuit for controlling a focus position of the initialization light beam based on the generated focus error signal; a focus error signal from reflected light from the optical information recording medium of the focus position coarse adjustment light beam; A second focus error detector for generating a focus error signal generated by the second focus error detector A second focus position control circuit for controlling a focus position of the initialization light beam and the focus position coarse adjustment light beam, a moving system for moving the optical head in a predetermined direction, and the first focus position control circuit; A controller for switching and operating the second focus position control circuit, and in the initial state, the focus position of the initialization light beam and the focus position of the focus position coarse adjustment light beam during operation of the second focus position control circuit; Is set so as to be a constant distance in the direction of the optical axis. 24. The optical recording medium initialization apparatus according to claim 23, wherein an optical path correction unit is provided on a specific optical path of a light beam emitted from at least one light source. The optical recording medium initialization apparatus according to claim 23, further comprising a counter that counts the number of vertical movements of the focal point of the initialization light beam. 24. The optical recording medium initialization apparatus according to claim 23, wherein wavelengths of the initialization light beam and the focal position coarse adjustment light beam are different. The optical recording medium initialization apparatus according to claim 24, wherein the optical path correction means is a liquid crystal element. The optical recording medium initialization apparatus according to claim 24, wherein the optical path correction means is a lens. A first light source that irradiates an initialization light beam, a second light source that irradiates a focus position coarse adjustment light beam, the initialization light beam, and the focus position coarse adjustment light beam are collected on the optical information recording medium. A first focus error detector for generating a focus error signal from reflected light from the optical information recording medium of the initialization light beam, and a focus position coarse adjustment light beam. A second focus error detector that generates a focus error signal from reflected light from the optical information recording medium, a focus error signal generated by the first focus error detector, and a second focus error detector Focus error signal selection circuit for selecting one of the focused error signals, and the focus error signal selection circuit Accordingly, a focus position control circuit for controlling the focus positions of the initialization light beam and the focus position coarse adjustment light beam based on the selected focus error signal, a moving system for moving the optical head in a predetermined direction, And a controller for switching between the focal position control circuit and the second focal position control circuit, and in the initial state, when the second focal position control circuit is operated, the focal position of the initialization light beam and the focal position coarse adjustment An optical recording medium initialization apparatus, wherein a focal position of a light beam is set to be a constant distance in an optical axis direction. 30. The optical recording medium initialization apparatus according to claim 29, wherein an optical path correction unit is provided on a unique optical path of a light beam emitted from at least one light source. 30. The optical recording medium initialization apparatus according to claim 29, further comprising a counter for counting the number of vertical movements of the focus of the initialization light beam. 30. The optical recording medium initialization apparatus according to claim 29, wherein wavelengths of the initialization light beam and the focal position coarse adjustment light beam are different. The optical recording medium initialization apparatus according to claim 30, wherein the optical path correction means is a liquid crystal element. The optical recording medium initialization apparatus according to claim 30, wherein the optical path correcting means is a lens.

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