JP2005322414A - Optical recording reproducing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly durable optical recording and reproducing apparatus by preventing adhesion of dirt and dust near to a light ejection section of an optical head. <P>SOLUTION: The optical recording and reproducing apparatus comprises a light source, an optical head for recording information by irradiating an information recording medium with light from the light source, and a detecting system for detecting the light returning from the information recording medium, wherein the optical head has a lens for condensing the light to the information recording medium and a substrate having a first surface and second surface parallel with each other and supporting the lens on the first surface. A projecting part or a protective pad is formed on the second surface of the substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical recording / reproducing apparatus for recording information on an optical recording medium using a high NA objective lens.

  In recent years, optical recording media capable of recording a large amount of data with high density and recording and reproducing at high speed have been used in response to the development of multimedia. This optical recording medium includes a read-only medium in which information is pre-recorded as pits on the disk when the disk is formed, such as a compact disk, a write-once medium that can be recorded only once, such as a CD-R, and a magneto-optical medium. There are rewritable media in which data can be rewritten any number of times using a recording method or a phase change recording method.

  Among these optical recording media, magneto-optical recording media are mainly used in fields that require a high transfer rate. When recording and reproducing the magneto-optical recording medium, the laser light is narrowed down to the diffraction limit with a lens and irradiated onto the magneto-optical recording medium. The size of the light spot formed on the magneto-optical recording medium by this laser light irradiation is about λ / NA, where λ is the wavelength of the laser light and NA is the numerical aperture of the lens.

  In order to record or reproduce a higher density, that is, a smaller pattern, a smaller laser beam spot is required. In order to reduce the light spot, it is conceivable to reduce the wavelength (λ) of the laser beam or increase the numerical aperture (NA) of the lens from the above formula. The numerical aperture (NA) of the lens is expressed as NA = sin θ where θ is the half angle of the lens aperture, and is a value smaller than 1. The NA of an objective lens used in an optical recording apparatus currently on the market is about 0.6 at most. The reason why the NA value is limited to about 0.6 is that coma and astigmatism that occur when the optical axis of the objective lens is tilted with respect to the disk surface increase as the NA increases. Because. In order to solve this problem, it is necessary to reduce the thickness of the transparent substrate of the disk through which light passes before reaching the magneto-optical recording layer of the magneto-optical recording medium. However, if the thickness of the substrate is reduced, the surface deflection of the disk increases due to a decrease in the rigidity of the substrate, and the substrate is inclined with respect to the optical axis of the objective lens.

  Thus, when light is irradiated onto the disk, it is considered that the light is incident from the side opposite to the disk substrate, that is, the so-called film surface side. Even if the film surface incidence method is employed in this way, various problems remain when a high NA objective lens is used.

  For example, in a magneto-optical recording apparatus, a magneto-optical head in which an optical system and a magnetic coil are integrated is known. Such a magneto-optical head is effective for recording information on the magneto-optical recording layer using a lens with a high NA. However, since the irradiated light heats the magnetic coil, the recording characteristics are deteriorated particularly when recording is performed by applying a high frequency modulation magnetic field. Japanese Patent Laid-Open No. 11-316986 discloses an optical head provided with a heat conductive film between a coil support member and a coil. Since the thermal conductive film has a thermal conductivity that is at least several times higher than the thermal conductivity of the coil support member, the heat generated in the coil is efficiently propagated to the objective lens through the thermal conductive film to increase the coil temperature. It is disclosed that it can suppress. However, when heat is propagated to the objective lens, there arises a problem that the optical characteristics of the lens deteriorate due to thermal expansion of the lens.

  A magneto-optical head normally uses two types of lenses as an objective lens system. When a high NA lens is used as an objective lens, the wavefront aberration due to the deviation of the optical axis of those lenses is not observed. It tends to occur. Since such wavefront aberrations deteriorate the reproduction signal characteristics, it is necessary to match the optical axes of the two types of lenses of the objective lens system with high accuracy.

  According to the first aspect of the present invention, there is provided an optical recording / reproducing apparatus for recording information on an information recording medium, which records information by irradiating the information recording medium with a light source and light from the light source. An optical head for detecting the light returning from the information recording medium, the optical head includes a lens for condensing light on the information recording medium, a first surface and a first surface parallel to each other. There is provided an optical recording / reproducing apparatus including a substrate having two surfaces and supporting the lens on a first surface, wherein a protrusion is formed on the second surface of the substrate.

  According to the second aspect of the present invention, there is provided an optical recording / reproducing apparatus for recording information on an information recording medium, which records information by irradiating the information recording medium with a light source and light from the light source. An optical head for detecting the light returning from the information recording medium, the optical head includes a lens for condensing light on the information recording medium, a first surface and a first surface parallel to each other. There is provided an optical recording / reproducing apparatus having two surfaces, a substrate for supporting the lens on the first surface, and a protective pad formed on the second surface.

  In the optical recording / reproducing apparatus of the present invention, since the protruding portion or the protective pad is provided on the second surface of the substrate, even if dust adheres to the disk, the optical transmission of the optical head is caused by the protruding portion or the protective pad. The optical recording / reproducing apparatus with high durability can be provided.

  In the optical recording / reproducing apparatus according to the first aspect of the present invention, a protective film may be formed on the surface of the protruding portion. By forming a protective film such as silicon oxide, silicon nitride, zirconia, or diamond-like carbon on the surface of the protruding portion, it is possible to provide an optical recording / reproducing apparatus having further excellent durability.

  In the optical recording / reproducing apparatus according to the second aspect of the present invention, the protective pad can be formed of various resin materials. Specifically, polyethylene, polystyrene, polypropylene, polycarbonate, polyacrylate, polymethacrylate, ABS resin, polyethylene terephthalate, polyacetal, polyarylate, nylon, polyetherimide, polyetheramide, phenolic resin, par Examples thereof include fluororesins such as fluoropolyethylene.

  In the optical recording / reproducing apparatus according to the second aspect of the present invention, the protective pads may be provided at the four corners of the second surface of the substrate. In this case, the protective pad may cover at least four corners of the second surface of the substrate. Further, the protective pad may cover the entire outer peripheral portion of the second surface of the substrate, or may be provided with pads isolated only at the four corners. Further, the protective pad may be attached to the second surface of the substrate or may be fitted into the substrate.

  In the present invention, the substrate may be a glass flat plate. When the light emission surface of the objective lens is flattened by using glass flat plates in which the first surface and the second surface are parallel to each other, the glass substrate is arranged at a right angle to the optical axis of the lens. It becomes easy to adjust the optical path after passing through the glass flat plate.

  In order to obtain a good light beam in the optical head, it is necessary to control the thickness of the adhesive layer to be constant when bonding the lens and the support substrate. By providing a support pad serving as a spacer between the lens and the support substrate, the thickness of the adhesive layer can be controlled to be constant. Thereby, it becomes easy to arrange the support substrate at right angles to the optical axis of the lens, and a good light beam can be obtained on the optical disc. The support pad is preferably made of metal. Further, when the pad is bonded using an adhesive, the adhesive may be filled in a portion (light transmission portion) between the disk substrate surface (second surface) and the lens light emission side end surface. It is desirable to select an agent having a refractive index close to that of the lens and the substrate. In the case where a gap is formed without filling this part with an adhesive, the lens light exit side end surface and the first surface of the substrate are reflected to prevent light from being reflected between the glass and the gap. A protective film can be formed.

  The numerical aperture (NA) of the lens can be 0.7 to 0.95. For ultra high density recording, a solid immersion lens having an NA of 1 or more can be used.

  The optical head can be mounted on a flying slider to form a flying head. In this case, a floating groove can be formed on the surface of the slider.

  As the information recording medium, for example, at least a reflective film, a recording layer, and a transparent dielectric layer are provided on a substrate provided with lands or grooves so that land recording or groove recording with a track pitch of 0.9 μm or less can be performed. Optical recording media stacked in order can be used.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. In this specification, the term “magneto-optical recording apparatus” intends an apparatus having not only recording but also a reproducing function.

  As shown in FIG. 1, a magneto-optical head 100 according to the present invention is used for recording information by applying a magnetic field while irradiating light to a magneto-optical disk 5 disposed therebelow. An objective lens system including the combination lenses 1 and 2, a lens holder 7 b that holds the lens 1, a lens holder 7 a that holds the lens 2, and a coil support substrate 3 having a magnetic coil 4 are included.

  A magnetic coil 4, which will be described in detail later, is embedded in the disk-side surface 3 a of the substrate 3. The lens 2 is disposed on the lens-side surface 3 b of the substrate 3 via a lens support pad 8. The lens 2 is processed such that the lens 2 has a light emitting portion, that is, the surface 2a facing the surface 3b of the substrate 3 is a flat surface, and the opposite side of the surface 2a is a convex spherical surface. The lens 2 is held in an opening formed on the bottom surface of a cylindrical lens holder 7a (holder outer frame).

  The lens 1 is a convex lens having convex spherical surfaces on both sides and a flat portion formed on the outer peripheral portion, and the flat portion of the lens is held by the upper end of a cylindrical lens holder 7b (holder inner frame). The lens holder 7 b has an opening on the bottom surface, and this opening allows light incident on the lens 2 to pass therethrough. The outer diameter of the lens holder 7b is substantially equal to the inner diameter of the lens holder 7a. By fitting the lens holder 7b to the lens holder 7a, the optical axes of the lenses 1 and 2 held by these lens holders are precisely aligned. ing. The NA of the objective lens system composed of these lenses 1 and 2 is 0.85.

  The space between the lens holder 7 a and the substrate 3 is filled with the adhesive 6 except for the light emitting portion 2 a of the lens 2. The adhesive 6 is also filled between the lens 2 and the opening formed at the lower end of the lens holder 7b. Further, the flat portion of the lens 1 is fixed with an adhesive 6 in the vicinity of the upper end of the lens holder 7a.

  The substrate 3 is made of transparent glass, and is polished so that the surfaces 3a and 3b are parallel to each other with high accuracy. The board | substrate 3 has an area larger than the bottom area of the lens 2 so that the light emission part 2a of the lens 2 may be covered completely. Although not shown in this figure, the magneto-optical head 10 is provided with an actuator that simultaneously performs focus servo and tracking servo (see FIG. 22).

  The lens holders 7a and 7b are preferably made of a material having a thermal expansion coefficient equivalent to that of the lens material for the following reason. In the present invention, disposing the heat radiating member on the disk side of the substrate surface suppresses propagation of heat generated in the magnetic coil to the lens by energizing the magnetic coil and light irradiation. Still, the temperatures of the lenses 1 and 2 and the lens holders 7a and 7b rise due to heat generated by light irradiation to the lenses. If the thermal expansion coefficients of the lens holders 7a and 7b and the lenses 1 and 2 are substantially the same, the thermal stress generated in the lenses 1 and 2 can be minimized to prevent deterioration of the optical characteristics of the lenses. When a hard glass such as BK7 having a small coefficient of thermal expansion is used as the material of the lens, copal, 42 alloy, 41 alloy, etc. as shown in Table 1 below are preferable as the material of the lens holders 7a, 7b. On the other hand, when a hard glass having a high coefficient of thermal expansion, such as soda glass, is used for the lenses 1 and 2, 426 alloy, 476 alloy, 50 alloy, etc. as shown in Table 1 are desirable. The components of each material and the coefficient of thermal expansion are shown in the table.

  Next, a bottom surface and a cross section of a substrate on which the magnetic coil 4 is provided (hereinafter also referred to as a magnetic coil substrate 90) will be described with reference to FIGS. As shown in FIG. 3 which is a cross-sectional view taken along line A-A ′ of FIG. 2, the substrate 3 is a glass substrate having a T-shaped cross-sectional shape. A portion 50 protruding from the disk-side surface 3 a of the substrate 3 functions as a light transmission part for the light emitted from the lens 2 to go to the magneto-optical disk 5. A soft magnetic layer 13 a is formed on the surface 3 a on the disk side of the substrate 3 outside the protruding portion 50 (light transmitting portion). The soft magnetic layer 13a is formed in an annular shape so as to surround the protrusion 50 as shown in FIG. The soft magnetic layer 13a can strengthen the magnetic field generated in the coil and control the magnetic anisotropy, and promote the diffusion of the heat generated in the coil 4.

  When the magnetic field generated in the coil becomes a high frequency, an eddy current flows in the soft magnetic layer, and the magnetic field may be reduced. For this reason, although not shown, the soft magnetic layer 13a has a structure in which a soft magnetic layer of about 2 μm is laminated via an insulating layer having a thickness of several nm, and this structure prevents the generation of eddy currents. Can do. In this example, the soft magnetic layer is made of permalloy, and the insulating layer is made of silicon oxide. The soft magnetic layer and the insulating layer can be formed by sputtering.

  Below the soft magnetic layer 13 a, a spiral magnetic coil 15 is formed so as to go around the light transmission part 50 via a resist 14 that functions as an insulating layer. The outer peripheral end 15 a of the magnetic coil 15 penetrates through a through hole 11 formed in the substrate 3 and is connected to a lead terminal 18 provided on the surface 3 b of the substrate. An inner peripheral end 15b of the magnetic coil 15 extends downward, turns and is bent upward toward the outer periphery of the substrate 3 so as to penetrate the through hole 11 formed in the substrate 3 and is provided on the surface 3b of the substrate. It is connected to a lead terminal 18. The maximum power consumption of the magnetic coil is 0.05 W or more. As can be seen from FIG. 4, which is a cross-sectional view taken along line B-B ′ in FIG. 2, a heat sink layer 80 is provided outside the magnetic coil 15 via a thin film of resist 14. The heat sink layer 80 is formed so as to surround the magnetic coil 15 and cover almost the entire surface of the substrate 3. The heat sink layer 80 functions to receive heat generated by the magnetic coil 15 and release it to the outside of the substrate 3, particularly to the space between the disk 5 and the substrate 3. The space between the disk and the coil can also be obtained by measuring the capacitance generated between the heat sink layer 80 and the disk using the heat sink layer 80. The distance between the disk and the coil is used to control the flying height of the magneto-optical head on the disk. The heat sink layer 80 is connected to the lead terminal 18 formed on the upper surface 3b of the substrate 3 through the through hole. A second soft magnetic layer 13 b is formed below the magnetic coil 15 via a resist 14. A protective layer 17 is formed at the lower end of the substrate so as to cover the soft magnetic layer 13b. A support pad 8 for supporting the lens 2 is formed on the surface 3 b of the substrate 3.

  A magnetic field application power source (magnetic field controller) (not shown) for supplying a current to the magnetic coil 15 is connected to the lead terminal 18. During operation of the magneto-optical head, light from a laser light source (not shown) is collected by the lenses 1 and 2, passes through the light irradiation unit 50, and is irradiated onto the magneto-optical disk 5. At the time of light irradiation, a current having a polarity corresponding to the recording signal is passed through the magnetic coil, and a magnetic field having a desired polarity is applied from the magnetic coil to the magneto-optical disk. In this way, information is recorded on the magneto-optical disk by the magnetic field modulation method.

  A manufacturing process of the substrate 3 including the magnetic coil 15 having the structure shown in FIGS. 2 to 4 will be described with reference to FIGS. First, as shown in FIG. 5A, a plurality of square regions 70 a where the magnetic coil substrate 90 is formed are partitioned on a transparent square glass substrate 70. For the glass substrate 70, a material having a uniform refractive index, a small refractive index change due to a temperature change, and a small thermal expansion is desirable, and BK7 which is a quartz glass is used. In each partition region 70a, as shown in the sectional view 5B, four through holes 11 penetrating the glass substrate 70 are formed using an excimer laser. After double-side polishing with an abrasive to make the thickness of the substrate uniform with high accuracy to a thickness of 0.300 mm, four through-holes as shown in FIGS. A Cr (or Ti) mask portion 82 was formed in the central portion of the substrate and serving as the light transmission portion (50). A sectional view of the substrate including the mask portion 82 is shown in FIG. Note that process steps (a) to (h) in FIG. 6 show processing for only one of the partitioned areas 70a for the sake of simplicity. The mask portion 82 can be formed by photolithography using a photomask. Next, as shown in FIG. 6B, 20 μm of the coil portion was removed by etching. For etching, ion etching using a reactive gas was used. Thereafter, the mask portion 82 was removed by ion etching while changing the reactive gas.

  Next, as shown in FIG. 6C, a soft magnetic layer 13a made of permalloy was formed on the etched surface of the glass substrate 3 by sputtering. At this time, the soft magnetic layer 13a was formed by laminating four layers of permalloy 2 μm through a silicon oxide layer (intermediate insulating layer) of 2 nm (not shown). Permalloy was formed by sputtering. Next, 1 μm of resist 14 was applied on the formed soft magnetic layer 13a and cured.

  Next, a resist 14 was further applied, the applied resist 14 was exposed using a mask pattern corresponding to the coil pattern and the heat sink layer, and developed to remove the portion of the resist that becomes the coil 15 and the heat sink layer 80. Then, the portion where the resist was removed was filled with copper to a thickness of 5 μm by plating. Thus, a copper coil 15a (coil upper layer) and a heat sink layer 80 were formed in the resist 14 as shown in FIG. The inner diameter of the coil was 120 μm, the outer diameter was 520 μm, and the number of turns was 20.5 turns.

  Further, as shown in FIG. 7E, a resist 14 serving as an insulating layer was applied so as to cover the coil 15 and smoothed. The thickness of the resist was 1 μm on the coil forming portion. Next, in order to wire the end portion of the coil 15 through the through-hole 11, a coil extension portion 15b (coil lower layer) was produced by the same process as the process shown in FIG. The coil extending portion 15b is formed so as to extend downward from the inner side of the coil 15a and then bend and extend toward the outer peripheral portion of the coil and bend toward the through hole 11 (see FIG. 7 (f)).

  Next, as shown in FIG. 7G, a resist 14 serving as an insulating layer was applied and smoothed. At this time, the resist thickness was 1 μm at the coil forming portion. Next, the second soft magnetic layer 13b is formed. As in the case where the soft magnetic layer 13a was formed on the glass substrate 3, the soft magnetic layer 13b was formed by laminating 2 layers of permalloy in 4 layers with an intermediate insulating layer of 2 nm therebetween. The disk-side soft magnetic layer 13b has an inner circumference larger than that of the coil 15 and the lens-side soft magnetic layer 13a, and the area of the inner diameter portion (opening) is twice the area of the inner diameter portion of the soft magnetic layer 13a. did.

  Next, as shown in FIG. 7H, as the protective film 17, 100 nm of silicon nitride and 20 nm of diamond-like carbon were formed in this order on the surface where the resist 14 and the soft magnetic layer 13b were exposed.

  Next, a lead terminal 18 and a lens support pad 8 are formed on the surface of the substrate on the lens side, and a 3 μm copper layer and a 1 μm gold layer are formed by plating in a predetermined resist pattern, and then the resist film is removed by ashing. (See FIG. 3). The lens support pad 8 is formed in an annular shape as shown in FIG. Finally, the substrate 70 was cut with a dicer for each partition region to obtain a plurality of magnetic coil substrates 90.

  As shown in FIG. 1, the lenses 1 and 2 were attached to the magnetic coil substrate 90 thus obtained in a state of being incorporated in the lens holders 7a and 7b, respectively. At this time, the lens holder 7a was positioned with respect to the substrate 3 while adjusting the optical path with respect to the light transmitting portion 50, and the adhesive 6 was filled between the lens holder 7a and the substrate 3 from the outer peripheral side of the lens holder 7a. As an adhesive, a polyurethane adhesive 3951 manufactured by Loctite was used. Here, the lens bonding pad 8 keeps the gap between the lens and the glass substrate for the coil constant, and prevents the adhesive from flowing into the light emitting portion of the lens 2. An antireflection film may be formed on the light emitting portion 2 a of the lens and the surface 3 b of the substrate 3.

  Example 2 of the magneto-optical head of the present invention will be described with reference to the drawings. In this example, a magnetic coil substrate was formed in the same manner as in Example 1 except that the lens support pad 8 ′ had four separated annular portions as shown in FIG. 9. As shown in FIG. 10, in the magneto-optical head 102, lenses 1 and 2 are assembled on a substrate 3 via lens holders 7a and 7b. Also in this example, the lens 2 is placed on the substrate 3 while controlling the distance between the lens 2 and the substrate 3 through the lens support pad 8 ′. Since the lens support pad 8 ′ is four separated annular portions, when the adhesive 6 is filled between the bottom of the lens holder 7 a and the substrate surface 3 b, the adhesive 6 is located below the light emitting portion 2 a of the lens 2. It flows into space. Here, since the refractive indexes of the lens 2, the substrate 3, and the adhesive 6 are substantially the same, the light is prevented from being refracted when propagating between them. Preferably, the difference in refractive index between the lens 2, the substrate 3, and the adhesive 6 is 10% or less. In this example, the lens and the substrate are made of quartz (BK7: n = 1.512), and the adhesive is a thermosetting adhesive, a two-part epoxy-EMI optical adhesive OPTOCAST 3601 (n = 1). .53) was used.

[Manufacture of magneto-optical disk]
In order to record / reproduce information with the magneto-optical head of the present invention, a magneto-optical disk having the cross-sectional structure shown in FIG. 13 was produced as follows. A land recording / reproducing substrate 21 having a track pitch of 0.6 μm was formed by filling a polycarbonate resin into an injection mold having a stamper in which grooves and pits were previously formed. The substrate size was 130 mm in diameter, 1.8 mm in thickness, and 15 mm in center hole diameter. The land width was 0.4 μm and the groove depth was 60 nm. Using an in-line DC magnetron sputtering apparatus on this substrate, the Au layer as the reflective layer 22 has a thickness of 50 nm, the TbFeCo alloy layer as the recording / reproducing layer 23 has a thickness of 20 nm, and the silicon nitride layer as the transparent dielectric layer 24 has a thickness of 60 nm. Each was formed with a thickness of. Next, an ultraviolet curable resin layer 25 is formed on the silicon nitride layer by spin coating with a thickness of 5 μm, and finally a perfluoropolyether lubricant having hydroxyl groups at both ends is spun at an average film thickness of 1 nm as a lubricant layer. Formed by coating. The film forming conditions for each layer are as follows. The silicon nitride layer was formed by sputtering a silicon target using an Ar—N ₂ mixed gas (mixing ratio 2: 1) at a flow rate of 130 sccm (vacuum degree: 2.0 Pa) and an input power of 2 kW. The Au layer was formed by sputtering an Au target with Ar gas at a flow rate of 80 sccm (vacuum degree: 1.2 Pa) and an input power of 2 kW. The TbFeCo alloy layer was formed by sputtering a Tb ₂₃ Fe ₆₇ Co ₁₀ (atomic%) alloy target using Ar gas at a flow rate of 100 sccm (vacuum degree: 1.5 Pa) and an input power of 500 W.

  This magneto-optical disk was incorporated into a drive equipped with the magneto-optical head manufactured in Example 1 and Example 2, and a predetermined test signal was recorded to measure an error rate. The tracking used the Push-Pull method. The disk rotation speed was 3600 rotations per minute.

  First, in order to measure the magnetic field from the magnetic coil 15 provided in the substrate 3 as shown in FIG. 1, a large coil used in the optical modulation recording system is sandwiched between the magnetic coil 15 and a disk. It installed in the position facing the magnetic coil 15, and the magnetic field which generate | occur | produces from this large sized coil was measured with the gauss meter. This is because it is difficult to directly measure the generated magnetic field because the magnetic coil 15 is very small, and the magnetic field generated by the large coil is applied as a bias magnetic field. Next, the disk was mounted on the drive and rotated, and the test signal was recorded on the disk by adjusting the laser power while applying focus servo and tracking servo. At this time, the bias magnetic field applied by the large coil and the magnetic field generated by the magnetic coil 15 are balanced to obtain a bias magnetic field at which the magneto-optical signal becomes zero, and the magnetic field generated by the coil of the present invention is determined. The current flowing through the coil 15 was adjusted to adjust the magnetic field generated from the magnetic coil of the magneto-optical head to 150 (Oe). The distance between the disk and the coil protective film 17 was 10 μm.

Using this drive, the error rate was measured at the optimum recording power. As a result, it was found that the mark with a mark length of 350 nm was 1 × 10 ⁻⁴ or less, and that the reproduction channel was at a sufficiently operating level. The data modulation method used was 1-7 (PR class 1). It can be seen that if the zone CAV method is used with this mark length, a storage capacity of about 15 Gbits can be achieved on one side of the disk.

  Here, in order to investigate how the area ratio of the openings of the soft magnetic layer 13a formed on the lens side and the soft magnetic layer 13b formed on the disk side affects the magnetic field generated from the magnetic coil 15. The area of the opening of the soft magnetic layer 13b formed on the disk side was changed to various values, and the magnitude of the generated magnetic field was measured. The results are shown in FIG. In the figure, the horizontal axis represents the ratio A / B between the area A of the opening of the soft magnetic layer 13b formed on the disk side and the area B of the opening of the soft magnetic layer 13a formed on the lens side. The vertical axis represents a value obtained by measuring the magnetic field with the same current for the disks having the different area ratios and normalizing the generated magnetic field of each disk with the maximum measured magnetic field (optimal area ratio). It can be seen that a magnetic field of 90% or more of the maximum measured magnetic field (optimal area ratio) is generated in the range of 1.2 ≦ A / B ≦ 3.1. Therefore, it is preferable that A / B is about 1.2 to 3.2.

  The magneto-optical head manufactured in Examples 1 and 2 can be mounted on an air slider 31 as shown in FIG. In this case, the disk and the lens can be brought close to each other stably without using the focus servo system. The air slider is connected to the rotary actuator via an arm (not shown). An optical system for sending laser light to the magneto-optical head can be attached to the tip of the arm. The magneto-optical recording signal and the signal necessary for tracking can be detected by, for example, a detection unit attached to the base of the arm. As the detection system, the same one as a known magneto-optical recording apparatus can be used.

  In this example, a magnetic coil substrate was manufactured in the same manner as in Example 1 except that the protrusions 50 were not left on the magnetic coil substrate 90 shown in FIG. As for a magnetic coil board | substrate 290, the glass material does not exist in the light transmission part 55 located in the center of the coil 15, as shown in FIG. Such a structure can be obtained without first etching the substrate 3, that is, by omitting the process steps (a) and (b) of FIG. Thus, when the protrusion 50 is made space, the coil manufacturing process is simplified, and the productivity is improved by obtaining an extremely smooth surface on the coil forming surface. The magnetic coil substrate 290 obtained in this way can constitute a magneto-optical head by incorporating an objective lens system in the same manner as in the first embodiment.

  In this example, as shown in FIGS. 15 and 16, a magnetic coil substrate 390 is formed in the same manner as in Example 1 except that a frame-like protrusion 70 is formed on the outer peripheral portion of the disk-side surface 3a of the coil support substrate 3. Manufactured. The protrusion 70 was formed to be higher than the protrusion 50 of the light transmission part. This protrusion 70 can be formed as follows, for example. In the process steps shown in FIGS. 6A and 6B, a mask is also provided on the outer portion corresponding to the protruding portion 70 of the substrate 3, and reactive etching is performed. Next, a mask may be formed only on the obtained protrusion 70, only the mask of the protrusion 50 may be removed, and further reactive ion etching may be performed. The protrusion 70 preferably protrudes from the protrusion 50 by about 1 to 2 μm. The protrusion 70 thus obtained protects the magnetic coil 15 and prevents adhesion of dust, dust, etc. in the vicinity of the light transmission part.

  Further, as shown in FIG. 15, the protective film 9 can be formed on the protrusion 70. As a material for the protective film 9, silicon oxide, silicon nitride, zirconia, diamond-like carbon, or the like can be used. The thickness of the protective film is preferably 0.1 to 0.2 μm.

An objective lens system was incorporated in the magnetic coil substrate 390 thus obtained in the same manner as in Example 1 to constitute a magneto-optical head as shown in FIG. The same magneto-optical disk produced in Example 1 was incorporated in a drive equipped with the magneto-optical head produced in this Example, a predetermined test signal was recorded, and the error rate was measured. The tracking used the Push-Pull method. The disk rotation speed was 3600 rotations per minute. The current flowing through the coil 15 was adjusted so that the magnetic field generated from the head coil was 150 (Oe). The distance between the disk and the coil protective film 14 was 10 μm. Using this drive, the error rate was measured at the optimum recording power. As a result, it was found that the mark with a mark length of 350 nm was 1 × 10 ⁻⁴ or less, and that the reproduction channel was at a sufficiently operating level. The data modulation method was 1-7 (PR class 1). It can be seen that if the zone CAV is used with this mark length, a storage capacity of about 15 Gbits can be achieved on one side of the disk.

  A magneto-optical disk recording / reproducing apparatus using the magneto-optical head manufactured in Example 4 as a pickup (fixed type) and a magneto-optical disk recording / reproducing apparatus using the magneto-optical head manufactured in Example 4 as a floating head are used. The magneto-optical disk produced in Example 1 was put into a 5.25 inch size ISO disk cartridge, and the cycle of disk storage and recording / reproducing test was repeated to examine the durability. This experiment was conducted in a normal office environment (temperature of about 25 ° C.). For comparison, silicon oxide, silicon nitride, zirconia, and diamond-like carbon are provided as protective films on the surface of the protrusions 70, no protective film, and protrusions 70 (pads) are not formed for comparison. We experimented.

  The results are shown in Table 2. Durability indicates the number of cycles in which the error rate deteriorates by 30% or more even in a sector of one track when 10 tracks are recorded / reproduced from the innermost circumference to the outermost circumference at several locations.

  In the pickup type head, when the disk enters the recording / reproducing apparatus, the disk is rotated for 5 seconds, and then the rotation is temporarily stopped. Next, the focus servo is operated on the inner periphery of the disk. Thereafter, the disk was rotated again, and then the head was moved from the inner periphery to the outer periphery, and control was performed so that several specific tracks were recorded and reproduced. The reason why the rotation of the disk is stopped once during the focus servo operation and the focus operation is started in the inner peripheral area is to prevent the focus servo from being pulled in due to the surface vibration of the disk. This is also for preventing the focus servo from coming off when the disk is rotated after the focus servo operation.

  The evaluation of the flying head is performed by rotating the disk, loading the head to the outer peripheral position on the disk by the ramp load method, moving it from the outer periphery to the inner periphery, recording and reproducing several specific tracks, and then It was performed by moving the head to the position and controlling it to unload.

  As shown in Table 2, the durability of the drive is improved by forming the protrusion 70 (pad). It can also be seen that durability is further improved by forming silicon oxide, silicon nitride, zirconia, and diamond-like carbon (DLC) as a protective film on the surface of the protrusion 70. In particular, when silicon oxide is formed on the surface of the protrusion 70 and diamond-like carbon (DLC) is formed thereon, the durability is remarkably increased. This is presumably because wear decreases and the friction coefficient decreases.

  The fifth embodiment is a modification of the fourth embodiment and will be described with reference to FIGS. In this example, a magneto-optical head was produced by providing a protective pad 91 as shown in FIG. 17 in place of the protrusion 70 in the magnetic coil substrate produced in Example 4. Such a magnetic coil substrate can be manufactured as follows. In the process steps shown in FIGS. 6A and 6B, reactive etching is performed by providing a mask not only on the protrusion 50 of the substrate 3 but also on the outer periphery corresponding to the protrusion 70. Thereby, the protrusion 70 can be formed at the same height as the protrusion 50. Then, the protective pad 91 may be bonded on the protrusion 70. The protective pad can be formed of a resin described later. As an example of the protective pad, a frame-type pad 91 provided on the entire rectangular outer periphery (edge) of the substrate is used as shown in FIG. As another example, bump-type pads 291 provided only at the four corners are used as shown in FIG. The protective pads 91 and 291 were prepared by molding a polyacetal or polyarylate resin into a predetermined shape using a mold prepared in advance. This pad was formed by sticking to the outer periphery of the substrate with an epoxy adhesive.

  Instead of sticking to the substrate 3 as shown in FIG. 18, the pad 91 may be formed so as to fit into the outer peripheral portion of the substrate 3 as shown in FIG. 19. The height of the pad is preferably about 1/5 to 1/2 of the distance between the magnetic coil and the disk surface. If it is less than 1/5, the protection capability of the coil is insufficient, and if it is more than 1/2, it is difficult to maintain the tilt accuracy when the magnetic field coil chip is attached, and mass productivity is reduced.

  Using the magneto-optical disk recording / reproducing apparatus using the magneto-optical head (pickup) with the pad as described above, the magneto-optical disk is put into a 5.25 inch size ISO disk cartridge, and the disk is stored and recorded / reproduced. The durability was checked by repeating the cycle. This experiment was performed in a normal office environment, and a pad made of polyacetal and a pad made of polyarylate were used as the pad, and a frame type and a bump type were tested as pad shapes. For comparison, an experiment was also conducted in which no pad was formed. The results are shown in Table 3 below. Durability indicates the number of cycles in which the error rate deteriorates by 30% or more even in a sector of one track when 10 tracks are recorded / reproduced from the innermost circumference to the outermost circumference at several locations.

  As can be seen from Table 3, the durability of the drive is improved by forming the coil protection pad with resin. Examples of protective pad materials include polyethylene, polystyrene, polypropylene, polycarbonate, polyacrylate, polymethacrylate, ABS resin, polyethylene terephthalate, polyacetal, polyarylate, nylon, polyetherimide, polyetheramide, phenolic resin, perfluoropolyethylene, etc. A fluororesin or the like can be used.

  FIG. 21 shows a modification of the first embodiment. The magnetic coil substrate shown in FIG. 21 is manufactured in the same manner as in Example 1 except that the thickness of the heat sink layer 800 is thicker than that in Example 1 and the lower end of the heat sink layer 800 is closer to the disk side. Yes. Since the heat sink layer 800 is closer to the disk side, the heat generated from the magnetic coil 15 and propagated to the heat sink layer easily escapes to the space between the disk and the substrate 3. Therefore, the heat dissipation effect of the heat sink layer is improved. Furthermore, the heat sink layer may be extended downward to be in contact with the protective film 17, or the heat sink layer may be exposed to the disk side without providing the protective film 17 partially. By doing so, the heat dissipation effect of the heat sink layer can be further improved.

  In this example, as shown in FIG. 26, a magnetic coil substrate was formed in the same manner as in Example 1 except that the magnetic coil 600 was formed in an elliptical shape, and a magneto-optical head was manufactured using it. The elliptical magnetic coil can be easily formed by exposing the photoresist using an elliptical spiral pattern as a photomask in the step of forming the coil shown in FIG. 6D.

  The reason why the magnetic coil 600 is formed in an elliptical shape is as follows. That is, it is necessary to track the disk when recording or reproducing information on the magneto-optical disk using the magneto-optical head. This tracking is performed by operating a galvano mirror provided in a fixed optical system (see FIG. 25) in which a laser light source and a detector are installed and a rotary actuator that supports a head via an arm. The light reflected by the galvanometer mirror is sent to a moving optical system such as a lens mounted on the head. Here, the high-speed operation in tracking is performed by the movement of the galvanometer mirror, but the light beam is swung in a direction (disk radial direction) perpendicular to the traveling direction of the disk by the movement of the galvanometer mirror. At this time, if the magnetic coil is shaped into an ellipse whose major axis is the radial direction of the disk, even if the light beam swings in the radial direction of the disk during tracking, the disk is irradiated without being blocked by the magnetic coil. be able to.

  In this embodiment, as shown in FIG. 27, a magnetic coil substrate is formed in the same manner as in Embodiment 1 except that a substrate 700 on which a magnetic coil is provided is formed in a rectangular shape. Was made. By making the glass substrate 700 rectangular, the area of the substrate on which one magnetic coil is installed can be reduced, and the manufacturing cost can be reduced. In this embodiment, the substrate 700 is 4.4 mm × 1.5 mm. A protective substrate 800 made of aluminum was installed on both sides of the glass substrate 700.

[Application to other recording media]
The magneto-optical head manufactured in the above embodiment records not only a magneto-optical head but also a phase change recording medium, particularly a film surface incident type phase change recording medium or a recording medium using a dye (for example, a CD-R). It can also be used for playback. A phase change recording medium or a recording medium using a dye does not have to apply a magnetic field for recording and reproduction, and can be used for the purpose of light irradiation without operating a magnetic coil. In this case, the protrusion on the substrate formed in Example 4 and the pad formed in Example 5 are a phase change recording medium, particularly a film surface incident type phase change recording medium or a recording medium using a dye (for example, a CD). The same durability using a phase change recording medium and a dye recording medium in place of the magneto-optical disk used in the durability test conducted in Example 4 is also effective when recording or reproducing -R). Trials revealed.

First, a phase change recording medium was produced by the following method. A land recording / reproducing substrate having a track pitch of 0.6 μm was molded by filling a polycarbonate resin into an injection mold equipped with a stamper in which grooves and pits were previously formed. The substrate size was a diameter of 120 mm, a thickness of 1.1 mm, and a center hole diameter of 15 mm. The land width was 0.4 μm and the groove depth was 60 nm. On top of that, using an in-line magnetron sputtering apparatus, an AgRuAu layer as a reflective layer is 100 nm thick, a ZnS—SiO ₂ layer is 20 nm thick as an intermediate layer, and a GeSnSbTe alloy layer is 20 nm thick as a recording layer. A ZnS—SiO ₂ layer having a thickness of 120 nm was formed as a dielectric layer.

An ultraviolet curable resin layer is formed on the ZnS-SiO ₂ layer by 5 μm spin coating, and finally a lubricant layer is formed by spin coating a perfluoropolyether lubricant having hydroxyl groups at both ends with an average film thickness of 1 nm. did. The film forming conditions for each layer are as follows. The ZnS—SiO ₂ layer was formed by sputtering a (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) target using Ar gas at a flow rate of 130 sccm (vacuum degree: 2.0 Pa) and an input power of 1 kW. The AgRuAu layer was formed by sputtering an Ag ₉₈ Ru ₁ Au ₁ (at%) target using Ar gas at a flow rate of 80 sccm (vacuum degree: 1.2 Pa) and an input power of 2 kW. The GeSnSbTe alloy layer was formed by sputtering a Ge ₁₅ Sn ₁₅ Sb ₁₅ Te ₅₅ (at%) alloy target using Ar gas at a flow rate of 100 sccm (vacuum degree: 1.5 Pa) and an input power of 200 W.

The phase change medium was put in a disk cartridge, and the cycle of disk storage and recording / reproduction test was repeated in the same manner as in Example 4 to examine the durability. As a result, almost the same result as in Table 2 was obtained. In addition, in the case of a dye recording medium using a dye layer using an azo dye and an Ag ₉₈ Ru ₁ Au ₁ (at%) reflective layer on a substrate, the same results as in Table 2 were obtained.

  From the above, not only the magneto-optical medium but also the film surface incident type phase change recording medium and the dye recording medium, the drive durability is improved by the formation of the protrusion 70, and the surface of the pad portion is made of silicon oxide or the like. It has been found that the durability is further improved by forming silicon nitride, zirconia, and diamond-like carbon as a protective film. When silicon oxide is formed on the surface of the protrusion 70 and diamond-like carbon is formed thereon, the durability is particularly increased in the same manner as in the magneto-optical case.

  In the above experiment, the magneto-optical head manufactured in the example was used. However, in the case of a phase change medium, an external magnetic field is not required for recording, and a magnetic coil without a magnetic coil can be used. That is, it is only necessary to omit steps (d) and (f) for forming the magnetic coil 15 in the process of forming the magnetic coil substrate shown in FIG. With such a process, a magnetic coil substrate without the magnetic coil 15 in FIG. 15 can be easily manufactured. With this substrate, heads can be constructed as shown in FIGS. 1, 12, and 17, such heads can operate as dedicated heads for recording and / or reproducing phase change media or dye recording media. .

  That is, in the present invention, an optical head used for recording information on an information recording medium, the lens for condensing light on the information recording medium; a first surface and a second surface parallel to each other; And an optical head comprising: a substrate that supports the lens on a first surface; and a protrusion or a protective pad provided on the second surface of the substrate. The protective pad can be made of a resin material as described above.

  As a result of various experiments and studies, in the case of the land / groove recording format in the magneto-optical recording medium and the phase change medium, the recording characteristics of the land and the groove are easily aligned. From the viewpoint of crosstalk with adjacent tracks, it was found that λ / (7n) to λ / (5n) is desirable. In addition, in the case of on-groove recording (recording on a convex portion when viewed from light incidence), since the recording power margin is wide and the tracking signal is sufficiently obtained, the polarization direction of the incident laser is parallel to the groove. desirable. If the groove depth is deeper than λ / (8n), the signal intensity decreases. If the groove depth is shallower than λ / (16n), a sufficient tracking signal cannot be obtained. Therefore, λ / (8n) to λ / (16n) Is desirable. Here, λ is the wavelength of the laser for reproduction, and n is the refractive index of the protective film, that is, the ultraviolet curable resin.

  The structure of the pickup unit 1000 in this embodiment will be described with reference to FIG. As shown in FIG. 22, the pickup unit 1000 is composed of a pickup body 101 and a pickup support 103 surrounding the pickup body 101.

  The pickup main body 101 mainly includes a first lens 110 for condensing light from an external optical system, which will be described later, and a second lens for further miniaturizing the spot diameter of the light collected by the first lens 110. A lens 112, a lens holder 114 for fixing the first lens 110, a lens holder 116 for fixing the second lens 112, a piezoelectric actuator 118 for adjusting the optical axes of the first lens 110 and the second lens 112, A magnetic coil 120 used for magneto-optical recording on a magneto-optical disk and a coil support substrate 122 for supporting the magnetic coil 120 on the magneto-optical disk side are constituted.

  As illustrated in FIG. 22, the second lens 112 is disposed on the coil support substrate 122, and the first lens 110 is disposed directly above the second lens 112. The first lens 110 is a convex lens having a flat surface on the outer peripheral portion and both surfaces form a convex spherical surface. The second lens 112 has a flat surface for fixing the holder on the outer peripheral portion, and the upper surface is a convex spherical surface. In addition, the lens is formed so that the lower surface is a flat surface. In the first lens 110, the light from the external optical system is condensed on the second lens 112, and the condensed light is further condensed on the magneto-optical disk by the second lens 112 so as to have a desired spot diameter. To do. The lens holder 114 has a cylindrical shape having a bottom surface, and fixes the first lens 110 on the upper frame of the lens holder 114. In addition, an opening for light incidence on the second lens 112 is provided at the center of the bottom surface of the lens holder 114. The lens holder 116 has a cylindrical shape having a bottom surface, and an opening having the same diameter as that of the second lens 112 for fixing the second lens 112 is provided at the center of the bottom surface.

  The lens holder 114 to which the first lens 110 is fixed is disposed inside the lens holder 116 so as to have a gap of about 100 μm. A piezoelectric actuator 118 is embedded in the outer peripheral portion of the bottom surface of the lens holder 114. Three piezoelectric actuators 118 are installed at intervals of 120 ° in the circumferential direction (FIG. 23). The piezoelectric actuators 118 are respectively grounded on the inner wall of the bottom surface of the lens holder 116 and support the lens holder 114 so as to be movable horizontally on the lens holder 116. By displacing the lens holder 114 in the horizontal direction with respect to the lens holder 116 and aligning the optical axis of the first lens 110 with the optical axis AX of the second lens 112, the optical axes of the first lens 110 and the second lens 112 are adjusted. Misalignment can be corrected. Thereby, it becomes possible to minimize the wavefront aberration generated by the deviation of the optical axes of the two lenses. In this embodiment, a piezoelectric actuator is used as the piezoelectric actuator 118. Wiring for the piezoelectric actuator 118 was performed by passing a twisted pair wire through a hole processed in the side wall or bottom surface of the lens holder 116 and fixing it to each piezoelectric actuator 118 by soldering.

  The pickup support unit 103 includes a pickup support unit main body 150, a focusing actuator 152, and an elastic member 158 for supporting the pickup main body unit 101 movably on the pickup support unit 103. The focusing actuator 152 is provided above the pickup support body 150 and between the pickup body 101. In this embodiment, the focusing actuator 152 includes an actuator coil 154 attached above the outer peripheral wall of the lens holder 116 of the pickup body 101 and an actuator permanent magnet 156. Since the pickup main body 101 is supported by the pickup support main body 150 via an elastic member 158 such as a leaf spring, it can be displaced in the vertical direction by the focusing actuator 152. Thereby, the pickup main body 101 can finely adjust the displacement in the vertical direction within the pickup unit 1000. Therefore, it is possible to finely adjust the focus on the magneto-optical disk.

  Hereinafter, a method for correcting the optical axis of the pickup unit 1000 used in this embodiment will be described with reference to FIG. This optical axis deviation correction is performed by adjusting the focusing actuator 152 and the piezoelectric actuator 118 using the magneto-optical disk 400. The magneto-optical disk 400 can be tracked from the diameter of the laser spot size determined by the lens NA and the wavelength of the laser used on the upper surface to an elliptical pit having a diameter of about 10 times (linear direction). Is formed. The magneto-optical disk 400 is rotated at a predetermined number of revolutions, and the pickup unit body 101 is displaced in the vertical direction (arrow ZD in the figure) using the focusing actuator 152, and the laser beam LS is magneto-optically picked up by the pickup unit 1000. The light is condensed on the disk 400. The light reflected from the pit passes through the second lens 112 and the first lens 110 and is reproduced by a magneto-optical signal detector of an external optical system described later. At this time, the best focus position is obtained from the displaced position of the pickup unit body 101 and the reproduction signal intensity.

  Next, among the playback signals obtained from pits of various sizes, the output from the small pit (minimum pit) is particularly large and the resolution (= playback signal from the minimum pit / playback signal from the maximum pit) The lens holder 114 is displaced in the horizontal direction (the arrow ZD in the figure) with respect to the lens holder 116 by applying a driving voltage to the piezoelectric actuator 118 so that it becomes larger. It is considered that the optical axis of the first lens 110 substantially coincides with the optical axis AX of the second lens 112 when both the signal from the minimum pit and the resolution are almost maximized. Here, in order to remove the magneto-optical disk 400 and fix the relative position of the first lens 110 and the second lens 112, the twisted pair wire that supplies the drive voltage to the piezoelectric actuator 118 is removed and the twisted pair wire is passed. The lens holders 114 and 116 are fixed by injecting an epoxy adhesive from the hole 134. It is also possible to perform the above adjustment when the magneto-optical disk 400 is loaded in the drive. In this case, a pit area for correcting the optical axis deviation is formed on the disk in advance, and the optical axis is adjusted by using a reproduction signal in this area.

  A specific example of the entire optical system of the magneto-optical recording apparatus incorporating the pickup unit 1000 according to the present invention is shown in FIG. As shown in FIG. 25, the embodiment of the present invention includes a movable optical system 200 including a pickup unit 1000, a fixed optical system 300, a magneto-optical disk 400, and a magnetic field control unit 500. In FIG. 25, as the fixed optical system 300, an optical system similar to a drive for recording or reproducing an ordinary magneto-optical disk can be used. That is, laser light emitted from a laser light source 302 such as a semiconductor laser passes through the lens 304, the prisms 306 and 308, and the beam splitter 310, is reflected by the mirrors 202 and 204, and then the first lens of the pickup unit 1000. 110, and is condensed by the second lens 112 and focused on the recording layer of the magneto-optical disk 400. At this time, the magnetic coil 120 in the pickup unit 1000 is supplied with a current corresponding to the recording signal from the magnetic field control unit 500, thereby generating a recording magnetic field from the magnetic coil 120. Thus, a recording mark corresponding to the recording signal is formed on the recording layer by the magnetic field modulation method. Here, the recording method is not limited to the magnetic field modulation method, and recording can also be performed by an optical modulation method or an optical pulse magnetic field modulation method.

  At the time of reproduction, the reflected light from the magneto-optical disk 400 is reflected by the mirrors 204 and 202, then reflected by the beam splitter 310, and split by the beam splitter 312 into light directed to the two beam splitters 314 and 326. The reflected light that has entered the beam splitter 314 is further split there, and enters the focusing detection detector 320 and the tracking signal detection detector 316, respectively. Further, the reflected light that has passed through the half-wave plate 322 and the lens 324 and entered the beam splitter 326 is incident on the photodetectors 328 and 330 that detect light components of mutually orthogonal polarization components, and depends on the Kerr rotation angle. The playback signal is detected.

  The magneto-optical head and magneto-optical recording apparatus according to the present invention have been described in detail with reference to the embodiments. However, the present invention is not limited to these embodiments, and those skilled in the art can claim the claims of the present invention. Various modifications and improvements that can be conceived from the above can be included. For example, various lenses can be used for the objective lens system mounted on the magneto-optical head, and a solid immersion lens that enables near-field recording may be used as a disk-side lens. Various shapes, dimensions, and materials may be adopted for the magnetic coil and the substrate. In the second embodiment, the adhesive is filled between the light emitting surface 2a of the lens 2 and the upper surface 3b of the substrate. However, the refraction at the interface between the lens 2 and the adhesive or the refraction at the interface between the adhesive and the substrate 3 is performed. In order to prevent further, oil for refractive index matching may be filled between the light exit surface 2a of the lens 2 and the upper surface 3b of the substrate. The oil may have a refractive index substantially the same as that of the material constituting the lens and the substrate.

  In the first to eighth embodiments, the through hole 11 is formed by the excimer laser. However, the through hole 11 may be formed by sand blasting using a mask instead of the excimer laser. Further, from the viewpoint of cost and mass productivity, the wiring pattern may be formed on the side surface of the substrate after forming the coil without forming the through hole 11 and forming the coil to the end of the coil.

  According to the magneto-optical head of the present invention, since the heat radiating member is provided on the surface on which the magnetic coil is provided on the magnetic coil substrate, that is, the side facing the magneto-optical disk, the heat generated by the magnetic coil is effectively used. In addition, heat can be radiated to the space between the magneto-optical disk and the magnetic coil. In particular, the magnetic coil can be effectively cooled using the airflow generated by the rotational movement of the magneto-optical disk. In particular, even when a high frequency signal is recorded, the magnetic characteristics of the magnetic coil are not disturbed, and good tracking is performed. Therefore, the magneto-optical head of the present invention and the magneto-optical recording apparatus equipped with it are extremely useful for high-density recording. In addition, the magneto-optical head of the present invention and the magneto-optical recording apparatus equipped with the magneto-optical head have a simple manufacturing process and can be manufactured at low cost.

  In the magneto-optical head of the present invention, since the actuator for moving the first lens holder relative to the second lens holder in the direction orthogonal to the optical axis of the lens is provided, the optical axes of the first lens and the second lens are accurately set. Can be combined. For this reason, even if a high NA lens is used for the second lens, the occurrence of wavefront aberration can be prevented. Therefore, the magneto-optical head of the present invention and the magneto-optical recording apparatus equipped with the magneto-optical head are extremely useful for high-density recording.

FIG. 1 is a schematic explanatory view showing the structure of the magneto-optical head manufactured in Example 1. FIG. FIG. 2 is a schematic transparent rear view of the magnetic coil substrate of the magneto-optical head of FIG. FIG. 3 is a schematic cross-sectional view of the magnetic coil substrate cut along the A-A ′ plane in FIG. 2. FIG. 4 is a schematic cross-sectional view of the magnetic coil substrate cut along the B-B ′ plane of FIG. 2. FIG. 5 is a diagram showing a processing process of the glass substrate used for manufacturing the magneto-optical head of Example 1, (a) is a plan view of the substrate on which through holes are formed, and (b) is ( It is sectional drawing of a), (c) is a top view which provided the mask part. FIG. 6 is a diagram showing process steps (a) to (d) for manufacturing the magnetic coil substrate of the magneto-optical head according to the first embodiment. FIG. 7 is a diagram showing process steps (e) to (h) for manufacturing the magnetic coil substrate of the magneto-optical head according to the first embodiment. FIG. 8 is a conceptual diagram showing the arrangement of lead terminals and lens support pads on the substrate in the magneto-optical head manufactured in Example 1. FIG. FIG. 9 is a conceptual diagram showing the arrangement of lead terminals and lens support pads on the substrate in the magneto-optical head manufactured in Example 2. FIG. FIG. 10 is a diagram showing a schematic structure of the magneto-optical head manufactured in the second embodiment. FIG. 11 is a schematic cross-sectional view of the magnetic coil substrate of the magneto-optical head manufactured in Example 3. FIG. 12 is a diagram illustrating the magneto-optical head of Example 2 mounted on an air slider. FIG. 13 is a schematic cross-sectional view of the magneto-optical disk manufactured in Example 1. FIG. 14 is a graph showing the change in the magnetic field generated from the magnetic coil 15 with respect to the area ratio A / B of the openings of the soft magnetic layer formed on the lens side and the soft magnetic layer formed on the disk side. FIG. 15 is a schematic cross-sectional view of a magnetic coil substrate formed in Example 4 and having a protruding portion 70 formed thereon. FIG. 16 is a schematic view showing the structure of a magneto-optical head incorporating the magnetic coil substrate shown in FIG. FIG. 17 is a view showing a schematic structure of a magneto-optical head having a magnetic coil substrate provided with a pad manufactured in Example 5. FIG. FIG. 18 is a diagram showing the shape of the pad 91 provided on the substrate of the magneto-optical head manufactured in the fifth embodiment. FIG. 19 is a view showing a mounting form (fitting type) different from FIG. 17 of the pads provided on the substrate of the magneto-optical head manufactured in Example 5. FIG. 20 is a view showing a bump-type pad 291 provided on the substrate of the magneto-optical head manufactured in the fifth embodiment. FIG. 21 is a schematic cross-sectional view of the magnetic coil substrate manufactured in Example 6. FIG. 22 is a diagram showing a schematic structure of the magneto-optical head (pickup unit) in the ninth embodiment. FIG. 23 is a cross-sectional view of the magneto-optical head of FIG. 22 cut along a plane orthogonal to the optical axis AX, and is a view for explaining the arrangement of piezoelectric actuators. FIG. 24 is a diagram conceptually illustrating the adjustment of the optical axis correction of the pickup in the ninth embodiment. FIG. 25 is a schematic diagram of an optical system of a magneto-optical recording apparatus using the pickup of the ninth embodiment. FIG. 26 is a schematic perspective rear view of a magnetic coil substrate having an elliptical magnetic coil pattern manufactured in Example 7. FIG. FIG. 27 is a schematic perspective rear view of a magnetic coil substrate having a rectangular substrate manufactured in Example 8. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Lens 3 Magnetic coil board | substrate 4,15 Magnetic coil 5,400 Magneto-optical disk 6 Adhesive 7a, 7b Lens holder 8 Lens support pad 11 Through hole 13a, 13b Soft magnetic layer 14 Resist 17 Protective film 21 Disk substrate 22 Reflection Layer 23 Recording layer 24 Transparent dielectric layer 31 Floating slider 32 Mirror 80 Heat sink layer 1000 Pickup part 101 Pickup body part 102 Pickup support part 110 First lens 112 Second lens 114, 116 Lens holder 118 Piezoelectric actuator 120 Magnetic coil 122 Coil support Substrate 130 Adhesive 132 Lens bonding pad 134 Hole 150 for the electron supply line of the piezoelectric element Pickup support body 152 Focusing actuator 154 Actuator coil 156 Actuator Permanent magnet 158 Elastic member 200 Movable optical system 300 Fixed optical system 302 Laser light source 304 Collimator lens 306, 308 Prism 310, 312, 314, 326 Beam splitter 316 Tracking signal detector 318, 324 Lens 320 Focus signal detector 322 1 / 2 wavelength plates 328, 330 Magneto-optical signal detector 500 Magnetic field controller

Claims (5)

An optical recording / reproducing apparatus for recording information on an information recording medium,
A light source;
An optical head for recording information by irradiating the information recording medium with light from the light source;
A detection system for detecting light returning from the information recording medium,
The optical head includes a lens for condensing light on the information recording medium, and a substrate having a first surface and a second surface parallel to each other and supporting the lens on the first surface, An optical recording / reproducing apparatus in which a protrusion is formed on a second surface of a substrate. The optical recording / reproducing apparatus according to claim 1, wherein a protective film is formed on a surface of the protruding portion. An optical recording / reproducing apparatus for recording information on an information recording medium,
A light source;
An optical head for recording information by irradiating the information recording medium with light from the light source;
A detection system for detecting light returning from the information recording medium,
The optical head includes a lens for condensing light on the information recording medium, and a substrate having a first surface and a second surface parallel to each other and supporting the lens on the first surface, An optical recording / reproducing apparatus in which protective pads are formed on two surfaces. The optical recording / reproducing apparatus according to claim 3, wherein the protective pad is made of resin. The optical recording / reproducing apparatus according to claim 3, wherein the protective pads are provided at four corners of the second surface of the substrate.

Images