JPH11242801A - Magneto-optical disk device, magnetic field generating device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use a generated magnetic field by providing a coil of a conductive pattern formed around the vicinity of a hole on a surface of a substrate and forming the thermal conductivity of this substrate so as to be larger than glass and the substrate so as to round off the corners. SOLUTION: A magnetic head 15 consists of a circular substrate 21 provided with a through hole 21a for an optical path on its center and a coil 22 made by the conductive pattern revolving the vicinity of this through hole 21a and formed on the surface. The substrate 21 is provided with a projection part of a front ball lens 13a in the through hole 21a, and is composed of the material with the thermal conductivity and heat radiation larger than the glass. Further, the substrate 21 is provided with a through hole 21b vertically penetrating through the outer end vicinity of the coil 22 and connection patterns 23, 24 prolonging from the insides of the through hole 21a and the through hole 21b to the outer peripheral edge. When a head drive voltage is applied to external electrodes 13c, 13d, a drive current flows through the coil 22 through the connection patterns 23, 24, and a signal is recorded on an optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magneto-optical disk device for recording signals of a magneto-optical disk, a magnetic field generator used for the same, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, recording and reproduction of information signals on an optical disk such as a magneto-optical disk (MO) are performed by an optical disk device. This optical disk device irradiates a rotating drive means such as a spindle motor for rotating the optical disk with light from a light source through an optical system including an objective lens to the rotating optical disk, and returns light from a signal recording surface of the optical disk. An optical pickup that detects an object lens with a photodetector via an objective lens, a biaxial actuator that supports the objective lens movably in a biaxial direction, that is, a focusing direction and a tracking direction, and a signal that is to be recorded on an optical disc based on a signal. And a magnetic field generator for generating a magnetic field.

[0003] Thus, in the case of reproduction, a light beam emitted from a light source of an optical pickup is focused on a signal recording surface of an optical disk via an optical system. The return light beam from the optical disk is separated from the light beam emitted from the light source by the optical system and guided to the photodetector. Thus, the information signal recorded on the optical disc is reproduced based on the detection signal from the photodetector. At this time, the light beam emitted from the light source follows the displacement of the optical disk in a direction orthogonal to the surface direction of the optical disk generated due to the warpage of the optical disk or the like, and is focused on the signal recording surface of the optical disk. Thus, the position of the objective lens in the optical axis direction is adjusted. At the same time, the position of the spot on the optical disc of the light beam emitted from the light source follows the eccentricity of the optical disc and the meandering of the track formed on the optical disc,
The position of the objective lens in the direction orthogonal to the optical axis is adjusted.

In the case of recording, a light beam emitted from a light source is condensed on a signal recording surface of an optical disk by an objective lens via an optical system. In this case, the light beam from the light source is set to high output, generates heat above the Curie temperature, and based on the magnetic field generated by the magnetic field generator,
Thermomagnetic recording of an information signal is performed on a signal recording surface of an optical disk.

[0005]

In the optical disk device having such a configuration, generally, the magnetic field generating device includes:
The optical disk is disposed on the opposite side of the optical pickup from the optical pickup, and is constituted by a coil formed by a conductive pattern on a substrate. By the way, due to the increase in the density of an optical disc, the distance between the objective lens and the optical disc, the so-called WD (Working Diode)
stance: working distance) becomes less than 100μm, for example.
The necessity of disposing the magnetic field generating device on the optical pickup side with respect to the optical disk becomes higher.

However, in order to dispose the magnetic field generator on the optical pickup side, the magnetic field generator must be disposed in a narrow space between the optical pickup and the optical disk, and the center of the coil is located at the center of the optical pickup. Since the optical path passes, it becomes difficult to increase the magnetic field generation efficiency of the coil, and it becomes necessary to supply a large current to the coil, and a hole making step for the substrate is required. Also, if a large current is applied to the coil, heat dissipation of the coil becomes a problem, and it is impossible to use a material having poor heat dissipation characteristics such as a polyimide film or glass epoxy as the substrate. On the other hand, when an attempt is made to use a substrate material having excellent heat dissipation properties, such a material is generally hard, and it is difficult to process the outer shape, and a dicing step is required. Since this dicing step is a step different from the above-described hole making step, there is a problem that the number of steps is increased.

Further, in the dicing step, if the substrate on which the coil is formed is made smaller, it is difficult to process the substrate. As a result, the yield at the time of dicing is reduced. If the generator is placed close to the optical disc, the corners of the substrate may come into contact with the optical disc, causing serious damage to the optical disc. Therefore, since the magnetic field generator is disposed apart from the optical disk, there is a problem that the magnetic field generated by the magnetic field generator cannot be used effectively.

[0008] In view of the above, the present invention provides a magnetic field generating device that is disposed close to an optical disk and effectively uses a magnetic field even when the magnetic field generating device is disposed on the optical pickup side. It is an object of the present invention to provide a magnetic field generator and a magneto-optical disk device using the same.

[0009]

According to the first aspect of the present invention, there is provided a circular substrate having a hole at the center, and a coil formed by a conductive pattern formed around the hole on the surface of the substrate. This is achieved by a magnetic field generator, wherein the substrate has a higher thermal conductivity than glass and has no corners.

Further, according to the second aspect of the present invention, a conductive pattern forming an annular coil is formed on the surface of a flat substrate material, and a protective film covering the conductive pattern is formed. And a second step of opening a through hole at the center of each coil, and a third step of cutting the periphery of each coil into a circle,
This is achieved by a method for manufacturing a magnetic field generator.

According to the first aspect of the present invention, since the outer shape of the substrate constituting the magnetic field generating device is formed in a circular shape without corners, the magnetic field generating device is disposed close to the optical disk. In this case, even if the substrate comes in contact with the optical disk, the outer shape of the substrate is circular and there are no corners, so that the optical disk is not seriously damaged.
Further, since the thermal conductivity of the substrate is high, the substrate has excellent heat dissipation characteristics, and can appropriately dissipate heat even when a large current is applied to the coil to increase the magnetic field generation efficiency. Therefore, the magnetic field generator is arranged close to the optical disk, and the utilization efficiency of the magnetic field generated by the magnetic field generator is improved.

According to the second aspect of the present invention, when the processing of the outer shape of the substrate (the third step) is performed by powder beam etching using a photomask, the substrate has a heat radiation property. Even if a high material is used, processing can be performed easily, and especially when this etching is performed from the surface on the coil side, the edge that may come into contact with the optical disk has an obtuse angle. Damage is further reduced. Furthermore, since the separation of each substrate is not performed by dicing, the degree of freedom of the arrangement of each substrate on the substrate material is increased, the utilization efficiency of the substrate material is increased, and more substrate materials of the same area are used. Will be manufactured.

According to the third aspect of the present invention, in the processing of the outer shape of the substrate (third step), a release sheet covering the entire front surface or the rear surface of the substrate is attached to the side opposite to the side to be etched. In this case, even if each circular substrate is cut off after etching, each circular substrate is in a state of being stuck to a release sheet, and does not fall apart and is easy to handle.

According to the fifth aspect of the present invention, when the processing of the outer shape of the substrate (third step) and the hole making in the center (second step) are performed simultaneously, the number of steps is reduced. As a result, the manufacturing cost is further reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
Since the embodiments described below are preferred specific examples of the present invention, various technically preferred limitations are added.
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows the configuration of an optical disk device incorporating one embodiment of a magnetic field generator according to the present invention. In FIG. 1, an optical disk device 10 includes a spindle motor 12 as a driving unit for rotatingly driving an optical disk 11 which is a magneto-optical disk, and an optical pickup 13.
And a feed motor 14 as a driving means thereof, and a recording magnetic head 15 as a magnetic field generator for recording information on the optical disk 11. Here, the drive of the spindle motor 12 is controlled by the system controller 16 and the servo control circuit 18 and is rotated at a predetermined rotation speed. The optical disc 11 can select and reproduce a plurality of types of optical discs. Therefore, for example, not only a magneto-optical disc but also a read-only optical disc such as a compact disc (CD) can be reproduced as an optical disc.

The optical pickup 13 irradiates a signal recording surface of the rotating optical disk 11 with light through an objective lens (not shown), based on a signal from a signal demodulator and an error correction circuit 17. And the recording magnetic head 1
5 together with the signal recording, and also detects the return light from the signal recording surface, and outputs a signal demodulator and an error correction circuit 17.
And outputs a reproduction signal based on the return light. As a result, the recording signal demodulated by the signal demodulator and the signal demodulation unit of the error correction circuit 17 is error-corrected through the error correction unit, and when the optical disk device 10 is used for data storage of a computer, The data is transmitted to an external computer or the like via the terminal 19. Thus, an external computer or the like can receive a signal recorded on the optical disk 11 as a reproduction signal. When the optical disk device 10 is for audio, the error-corrected recording signal is subjected to digital / analog conversion by the D / A converter of the D / A, A / D converter 20, as indicated by the dotted line. And output as an audio signal.

A feed motor 14 for moving the optical pickup 13 to a predetermined recording track on the optical disk 11, for example, is connected to the optical pickup 13. The servo control circuit 18 controls the spindle motor 12 and the feed motor 14, and controls the focusing direction and the tracking direction of the biaxial actuator for holding the objective lens of the optical pickup 13.

FIG. 2 shows an embodiment of a recording magnetic head as a magnetic field generator according to the present invention. In FIG. 2, the recording magnetic head 15 includes a front lens 13a and a front lens 13b that hold a front lens 13a that is biaxially driven and controlled by the biaxial actuator of the optical pickup 13. It is attached to the opposite side, that is, the end face on the optical disk side. still,
In the figure, the front lens 13a of the lens holder 13b
Below this, an objective lens (not shown) is arranged, and is driven and controlled by the biaxial actuator together with the lens holder 13b. Here, the front lens 13a is, as shown in the figure,
The lower side, that is, the light source side is formed in a convex shape, and the upper side, that is, the optical disk side, is formed as a plane having a small convex portion 13e provided in the center.

The recording magnetic head 15 has a circular substrate 21 having a through hole 21a for an optical path at the center, and a conductive pattern formed on the surface so as to circulate around the through hole 21a of the substrate 21. , And a coil 22. As a result, the substrate 21 has its through hole 21a
The projection of the front lens 13a is received therein. The substrate 21 is made of a material having higher thermal conductivity and higher heat dissipation than glass, such as AlN (aluminum nitride) and sapphire glass (Al ₂ O ₃ : aluminum oxide). A through hole 21b vertically penetrating is provided near the outer end.
Connection patterns 23 and 24 extending from inside 1b to the outer peripheral edge are provided.

On the other hand, the lens holder 13b
The recording magnetic head 15 is provided on the end surface on the optical disk side.
Are attached to the positions corresponding to the outer ends of the connection patterns 23, 24.
Are provided with external electrodes 13c and 13d which are in contact with the outer ends of the. Therefore, when a head drive voltage is applied to the external electrodes 13c, 13d, the external electrodes 13c, 13d
A drive current flows through the coil 23 via the connection pattern 23 and the connection patterns 23 and 24, and signal recording on the optical disk 11 is performed.

FIG. 3 shows a first embodiment of a method for manufacturing a recording magnetic head 15 as a magnetic field generator according to the present invention. First, in FIG. 3A, individual recording magnetic heads are formed on the surface of a large substrate material 30 in a wafer state (only a portion corresponding to one recording magnetic head 15 is shown in the drawing). A resist pattern 31 corresponding to the spiral conductive pattern which should constitute the fifteen coils 22 is formed using, for example, a photomask. In this case, since the mask 31 has no holes formed on the substrate material 30, a fine pattern can be formed. Next, in FIG. 3B, a conductive pattern 32 constituting the coil 22 is formed on the resist pattern 31 by plating with copper or the like. In this case, for example, a conductive pattern having a low electric resistance value is formed by using both electroless plating and electrolytic plating. Subsequently, in FIG. 3C, after the resist pattern 31 is removed, a surface protection film 33 is formed so as to cover the conductive pattern 32. In this case, since there is no need to provide a through hole for connection on the surface side of the substrate material 30, the selection range of the material of the surface protective film 33 is wide, and for example, a fluorine-based material having excellent lubricating properties, abrasion resistance, or the like. A material with poor workability such as SiN having excellent workability can be selected, and the surface protection characteristics are improved.

Thereafter, as shown in FIG. 3D, a release sheet 34 is attached to the entire surface of the substrate material 30 from above the surface protection film 33. Here, as the release sheet,
For example, a foam release sheet or an ultraviolet release sheet is used. That is, this foamed release sheet loses its adhesiveness when heated, and for example, “Riba Alpha” manufactured by Nitto Denko Corporation is suitable. The UV release sheet is a sheet that loses its adhesiveness by being irradiated with ultraviolet rays, and is preferably, for example, a “dicing sheet D-series” manufactured by Lintec Corporation. Are the recording magnetic heads 15
Through hole 21a, through hole 21b and individual substrate 2
A resist pattern 35 having a shape for forming the outer shape 1 is formed using a photomask or the like. In this case, as the resist pattern 35, an appropriate resist is selected according to a subsequent etching process, and for example, a powder beam resist is used.

Next, referring to FIG.
The through-hole 36 is processed by powder beam etching by blowing a powder beam from the back surface of the through hole 36. That is, with respect to the substrate material 30, the through holes 3
6a, a through hole 36b and an outer shape separating groove 36c are formed. Here, when the substrate material 30 is formed of, for example, aluminum nitride among the aforementioned materials and the coil 22 is formed of copper, the selectivity of aluminum nitride to copper in powder beam etching is 20 or more. That is, the processing speed (processing rate) of aluminum nitride is 20 times or more the processing rate of copper. Therefore, a through hole is formed in the substrate material 30 without particles penetrating the coil 22 during processing. As the powder, SiC of about # 600 is used. Thus, since hard particles are used, the deterioration of the particles is slow, and the processing rate is hardly reduced, so that stable powder beam etching is performed. Here, the outer portion is cut off by the outer shape separating groove 36c so that the inner portion thereof
Even if the inner portion is separated from the release sheet 34,
Is held without being separated.

Finally, in FIG. 3F, using a pattern mask (not shown), the back surface of the substrate material 30 and the inside of the through holes 36a and the through holes 36b are plated to form a conductive material as the connection pattern. The pattern 37 is formed, and the pattern mask is removed. In this case, the taper angle of the through hole 36a and the through hole 36b is 60 to 7
By setting the angle to about 0 degree, the degree of adhesion can be increased since the plating pattern is formed on the inclined wall portion as compared with the case of vertical. As a result, a thick plating pattern can be formed, and the electrical resistance is reduced accordingly. Therefore, the plating thickness can be reduced as long as the electrical resistance is the same as that formed in the vertical hole. Thereafter, the release sheet 34 is peeled off, whereby the individual recording magnetic heads 15 are completed.

The optical disk device 10 according to the present embodiment
When the recording magnetic head 15 is assembled, the front lens 13a of the optical pickup 13 is constructed as described above.
The substrate 21 is placed and fixedly held such that the lower surface of the substrate 21 is in contact with the end surface of the lens holder 13b on the optical disk side. Therefore, the outer ends of the connection patterns 23 and 24 exposed on the lower surface of the substrate 21 come into contact with the external electrodes 13c and 13d provided on the lens holder 13b to be electrically connected. Therefore, the lens holder 13
By being directly attached to the optical pickup b, it is disposed between the optical pickup 13 and the optical disk 11.

According to the optical disk apparatus 10 assembled in this manner, in FIG. 2, light from a light source (not shown) is transmitted from below to the optical disk 1 via the front lens 13a.
The signal to be recorded is input to the external electrodes 13c and 13d of the recording magnetic head 15 based on the signals from the signal demodulator and the error correction circuit 17 while being imaged on the signal recording surface of the recording medium. As a result, a drive current flows from the external electrodes 13c and 13d to the coil 22 via the connection patterns 23 and 24, and signal recording on the optical disk 11 is performed.

In this case, since the outer shape of the substrate 21 is formed without dicing and has a circular shape without corners, the recording magnetic head 15 which is a magnetic field generator is used.
When the recording magnetic head 15 is disposed close to the optical disk 11, the outer edge of the substrate 21 of the recording magnetic head 15 does not significantly damage the optical disk 11 even if the recording magnetic head 15 contacts the optical disk 11. Also,
When a large current is applied to the coil 22 of the recording magnetic head 15, a substrate material having excellent heat dissipation is used,
The effect of the heat generated by the coil 22 is reduced, and the substrate material is easily separated in a circular outline by etching, for example, powder beam etching, instead of the dicing process. Further, since the through hole 21a at the center of the substrate 21 and the outer edge are processed at the same time, the number of steps can be reduced,
Costs will be reduced.

The substrate 21 of the recording magnetic head 15
The wafer-like substrate material 30 is cut off by powder beam etching. For this reason, since each substrate 21 is arranged in a zigzag pattern on the substrate material 30 as shown in FIG. 4 (A), the substrate 21 is cut in the vertical and horizontal directions by a dicing process to form a grid. The arrangement is performed at a higher density than the arrangement (see FIG. 4B). Therefore, a larger number of substrates 21 and recording magnetic heads 15 are manufactured from the same area of the substrate material 30.

FIG. 5 shows a second embodiment of the method for manufacturing a recording magnetic head as a magnetic field generator according to the present invention. First, in FIG. 5A, a spiral spiral to constitute the coil 22 of each recording magnetic head 15 is formed on the surface of the large substrate material 40 in the wafer state in the same manner as in FIG. 3A. A resist pattern 41 corresponding to the conductive pattern is formed using, for example, a photomask. Next, in FIG. 5B, a conductive pattern 42 constituting the coil 22 is formed from above the resist pattern 41 by plating with copper or the like in the same manner as in the case of FIG. 3B. Subsequently, in FIG. 5C, after the resist pattern 41 is removed, a surface protection film 43 is formed so as to cover the conductive pattern 42 in the same manner as in the case of FIG. 3B.

Thereafter, as shown in FIG.
A resist pattern 45 having a shape corresponding to the through hole 21a and the through hole 21b of each recording magnetic head 15 is formed on the back surface of the recording magnetic head 15 using a photomask or the like.

Next, referring to FIG.
The through-hole 46 is processed by powder beam etching by blowing a powder beam from the back surface of the substrate. That is, with respect to the substrate material 40, the through holes 4
6a and a through hole 46b are formed.

Then, in FIG. 5F, using a pattern mask (not shown), the back surface of the substrate material 40 and the inside of the through holes 46a and the through holes 46b are plated with a conductive pattern as the connection pattern. 47 are formed, and the pattern mask is removed.

Finally, in FIG. 5 (G), the substrate material 4
A release sheet 44 is attached to the entire back surface of the “0”. Further, on the surface of the substrate material 40, each recording magnetic head 15
Resist pattern 4 that forms the outer shape of substrate 21
8 is formed by a photomask or the like, and a powder beam is blown from the surface of the substrate material 40 to form a through hole by powder beam etching, that is, an outer shape separating groove 49. In this case, even if the inner portion is separated from the substrate material 40 by the outer shape separating groove 49, the inner portion is held without being separated by being held by the release sheet 34. Thereafter, the release sheet 44 is peeled off, whereby the individual recording magnetic heads 15 are completed.

According to the manufacturing method having such a configuration, the first
The following effects are exhibited in addition to the same effects as those of the embodiment. That is, the outer edge formed by the separation groove 49 of the substrate 21 has an obtuse angle of 90 degrees or more (for example, about 120 to 130 degrees) on the optical disk side. Is prevented, and even if the recording magnetic head 15 comes into contact with the optical disk 11, damage to the optical disk is further reduced.

In the embodiment described above, the coil 22 of the recording magnetic head 15 is formed in one layer on the substrate 21, but is not limited to this, and may be two or more layers. As a result, a stronger magnetic field is generated. Further, when the coil 22 is an even layer, the coil 2
The two connections from both ends to the outside are both coils 22
Can be provided on the outer peripheral portion of the device, and connection to the outside can be performed more easily and with low resistance. Further, in the above-described embodiment, the recording magnetic head 15 uses the through hole 21a at the center of the substrate 21 as an optical path of the front lens 13a and receives the convex portion of the front lens 13a. However, it is clear that the present invention can be applied even when the front lens 13a has no convex portion. Furthermore, the recording method of the magnetic field generating device and the magneto-optical disk device of the present invention is based on magnetic field modulation,
The method can be applied to either of the methods based on light modulation.

[0037]

As described above, according to the present invention, even when the magnetic field generator is provided on the optical pickup side, the magnetic field generator is provided close to the optical disk and the magnetic field is effectively generated. A magnetic field generator and a magneto-optical disk device using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing the configuration of an optical disk device incorporating one embodiment of a recording magnetic head as a magnetic field generator according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a configuration of a recording magnetic head in the optical disk device of FIG.

FIG. 3 is a schematic view sequentially showing the steps of the first embodiment of the manufacturing steps of the recording magnetic head of FIG. 2;

FIG. 4 is a schematic plan view showing (A) the arrangement of individual substrates and (B) the arrangement of substrates separated by conventional dicing with respect to the substrate material in the manufacturing method of FIG.

FIG. 5 is a schematic view sequentially showing steps of a manufacturing process of the recording magnetic head of FIG. 2 according to a second embodiment.

[Explanation of symbols]

10 optical disk device, 11 optical disk, 1
2 ... Spindle motor, 13 ... Optical pickup, 14 ... Feed motor, 15 ... Recording magnetic head (magnetic field generator), 16 ... System controller,
17: signal modulator / demodulator and ECC, 18: servo control circuit, 19: interface, 20: D /
A, A / D converter, 21: substrate, 21a: through hole, 21b: through hole, 30, 40: substrate material, 31, 41: resist pattern, 32, 42
... conductive patterns (coils), 33, 43 ... surface protective films, 34, 44 ... release sheets, 35, 45 ...
.Resist pattern, 36, 46 ... through-hole, 36c
··············································································

Claims (6)

[Claims] 1. A circular substrate having a hole at the center thereof, and a coil formed of a conductive pattern formed around the hole on the surface of the substrate, wherein the substrate has a thermal conductivity larger than that of glass. A magnetic field generator characterized by being formed without corners. 2. A first step of forming a conductive pattern constituting an annular coil on the surface of a flat substrate material, forming a protective film covering the conductive pattern, and forming a through hole at the center of each coil. A method for manufacturing a magnetic field generator, comprising: a second step; and a third step of cutting the periphery of each coil into a circle. 3. The method according to claim 2, wherein the third step is performed by powder beam etching using a photomask. 4. The method according to claim 3, wherein, prior to the third step, a release sheet covering the entire front surface or the rear surface of the substrate is attached to the side opposite to the side on which the etching is performed.
3. The method for manufacturing a magnetic field generator according to claim 1. 5. The method according to claim 2, wherein the third step is performed simultaneously with the second step. 6. A rotation driving means for driving the optical disk to rotate, irradiating the optical disk with light through an objective lens, and detecting a return light from a signal recording surface of the optical disk by a photodetector through the objective lens. An optical pickup; a biaxial actuator that supports the objective lens so as to be movable in biaxial directions, that is, a focusing direction and a tracking direction; a signal processing circuit that generates a reproduction signal based on a detection signal from a photodetector; A magneto-optical device comprising: a servo circuit for moving an objective lens of an optical pickup in two axial directions based on a detection signal from the optical disc; and a magnetic field generator for generating a magnetic field for performing thermomagnetic recording on an optical disk. A disk device, wherein the magnetic field generator circulates around a hole on a surface of a circular substrate having a hole in the center. And a coil due to formed conductive pattern as the substrate is larger thermal conductivity than glass, yet the magneto-optical disk device characterized by being formed so as not square.