JPH05166219A - Optical head and assembly method therefor and information processor - Google Patents

Abstract

PURPOSE:To miniaturize the device by providing an actuator for driving an objective lens part on a base body and providing a light emitting part with a pedestal part provided on the base body and a semiconductor laser chip. CONSTITUTION:The heat generated in the semiconductor laser chip 20 is transmitted through the semiconductor pedestal 24 and metallic pedestal 23 to a housing 15 and is radiated by the housing 15. Then, the housing 15 functions as a heat sink and, therefore, there is no need for separately providing a heat sink and the reduction of the thickness of the optical head is possible. The two-dimensional actuator 100 is constituted to drive only the objective lens 50 and can, therefore, execute tracking control and focus control with a small driving force. Since the semiconductor pedestal 24 is used as the pedestal in contact with the semiconductor laser chip 20, the semiconductor laser is kept free from the stress by a difference in the coefft. of thermal expansion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head for irradiating an optical disk with laser light and detecting reflected light.

[0002]

2. Description of the Related Art As the information-oriented society has advanced, optical disks, which are large-capacity memories, have become widespread. Optical discs are classified into a read-only type, a write-once type, and a rewritable type. The read-only type optical disc, as typified by a compact disc and a video disc, has recorded information recorded on a substrate in a concavo-convex shape by a stamper or the like, and is supplied inexpensively and in a large amount. On the other hand, the write-once type and rewritable type optical disks record information by heating the recording material thin film by irradiation with laser light to cause pit formation, phase change, or magnetization reversal, and are used for recording information such as document files and image files. The demand for large-capacity memory media for offices and individuals is increasing.

An example of such an optical disk is shown on pages 189 to 213 of Nikkei Electronics, 1983.11.21. An optical system for a compact disc is known, for example, by Shigeo Kubota, “Small size, light weight, and simplification of optical disc pickup”, Vol. 16, No. 8 (1987), and the like.

On the other hand, a small and thin personal information processing apparatus represented by a laptop type or notebook type personal computer and a workstation has been developed. These are space
Because of its excellent efficiency and portability, it is becoming the mainstream of information processing devices in place of conventional desktop type devices. Some of these information processing devices have an A4 size and a thickness of 30 m.
Some of them are thinner than m, and it is the momentum for further downsizing. At the same time, there is a remarkable increase in the performance of information processing devices, and the amount of information handled has dramatically increased from character information to voice and images, and some of the basic system software alone exceeds 100 MB. is there.

An optical disc having a large capacity and a low bit cost is suitable as a memory device for these small and thin personal information processing devices. In this case, a write-once or rewritable optical disk is desirable. However,
The thickness of conventional write-once and rewritable optical disk devices is 4
It has a size of 0 mm to 50 mm or more, and has a larger package than the conventional floppy disk, hard disk, and IC card, and is suitable for the above-mentioned small and thin information processing apparatus and other portable information apparatus. Could not be loaded into memory.

This is because the optical system of the conventional optical disk has the same basic structure from an optical disk having a diameter of 300 mm to an optical disk having a diameter of 90 mm, and all the optical disk substrates are standardized to have a thickness of 1.2 mm. is there. That is, in order to focus a laser beam through an optical disc substrate having a thickness of 1.2 mm, it is necessary to use an objective lens having a diameter of about 3.5 mm or more, which is a main factor limiting the thinning of the optical head. It was. According to the conventional standard, although there is an advantage that optical components can be shared between different devices, it is not possible to reduce the thickness and it is impossible to mount the optical disc device on a small and thin information processing device.

Therefore, by breaking the conventional standard,
An apparatus for thinning an optical head is currently being developed by using an objective lens having a small diameter for converging a laser beam on an optical disc thinner than 1.2 mm.

As a small read-only type optical head, in Japanese Patent Laid-Open No. 2-273238, a semiconductor laser, a light receiving element, an objective lens, and a light reflecting portion are mounted on a movable body by a common holding member. An optical head has been proposed in which the movable body is held at the drive position and is driven by a drive mechanism to perform tracking control. With such a read-only optical head,
A semiconductor laser with an output of about 5 mW may be mounted. However, in a write-once or rewritable type optical disk head, in order to record and erase information on the optical disk, it is necessary to
It is necessary to mount a high output semiconductor laser of 0 mW to 50 mW as a light source. In addition, in the write-once or rewritable type optical disk head, compared to the read-only type,
Since the degree of modulation of the reproduced signal is generally small, a high frequency oscillator is often added to the semiconductor laser in order to reduce the noise of the semiconductor laser and obtain a sufficient S / N. Because of these, the semiconductor laser and the element to be added generate a large amount of heat. The characteristics of the semiconductor laser, such as the oscillation wavelength, the oscillation threshold current, and the service life, change according to the temperature change. A heat sink with sufficient heat capacity is needed.

[0009]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2-27323
The optical head described in Japanese Patent No. 8 has a structure in which a semiconductor laser chip is held on a movable body via a holding member to achieve miniaturization, and tracking control is performed by driving the entire movable body. For this reason, if the heat capacity of the movable body is increased, the weight also increases and the tracking performance of tracking control deteriorates, causing a data reproduction error.

An object of the present invention is to solve the above problems, provide a thin optical head having a sufficient heat capacity, and reduce the size of write-once and rewritable optical disk devices.

[0011]

In order to achieve the above object, according to the present invention, a light emitting section for emitting a laser beam, an objective lens section for condensing the laser beam, and the laser are provided on a substrate. An optical head comprising: an optical element for guiding light to the objective lens; and a photodetector section for detecting the laser light, wherein the optical lens focuses the laser light on an optical disc and detects reflected light. There is provided an optical head, further comprising an actuator for driving the unit, wherein the light emitting unit has a pedestal portion provided on the base and a semiconductor laser chip fixed on the pedestal portion. ..

[0012]

According to the optical head of the present invention, a light emitting section for emitting a laser beam, an objective lens section for condensing the laser beam, an optical element for guiding the laser beam to the objective lens are provided on a substrate. And a photodetector for detecting laser light. An actuator that drives the objective lens unit is also provided on the base. The light emitting unit is configured by providing a pedestal on the base and fixing a semiconductor laser chip on the pedestal. The substrate includes a light emitting section, an optical element, an objective lens section,
It serves as a reference for the optical path of the laser beam formed by the photodetector. Further, the base body serves as a substrate that supports an actuator that drives the objective lens.

The pedestal conducts heat generated during the operation of the semiconductor laser to the base. The substrate receives the heat generated by the semiconductor laser chip and radiates the heat to the surroundings. In this way, the substrate
By providing the function of the heat sink that radiates the heat generated by the semiconductor laser chip, the heat sink that has been used conventionally becomes unnecessary. Therefore, the size of the heat sink is not limited, and the optical head can be thinned.

Further, in the present invention, an actuator for driving the objective lens section and performing tracking control is provided on the base. The actuator performs tracking control by driving only the objective lens unit. Since the objective lens unit has a very small weight, the actuator only needs to have a small driving ability.

It is important to reduce the heat transfer resistance between the semiconductor laser chip and the substrate and prevent the change over time. In the structure of the conventional optical head, the semiconductor laser module and the base body of the optical head are fixed to the base body, which is a base, by screws or adhesives. In the present invention, a pedestal is formed on the base body and the semiconductor laser chip is bonded onto the pedestal. The base and the base, and the base and the semiconductor laser chip are bonded to the base by a method having high thermal conductivity. For example, the pedestal and the base are integrally formed, or a separate pedestal is bonded with solder, silver solder, adhesive or the like having high thermal conductivity. The pedestal and the semiconductor chip are also joined with a material having high thermal conductivity. As a result, the heat generated by the semiconductor laser chip can be directly transferred to the substrate, which enables thermal stabilization and miniaturization of the optical head.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

First, a rewritable optical head according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a pedestal 22 is fixed on the housing 15 which is a base, and a semiconductor laser chip 20 is fixed on the pedestal 22.
The pedestal 22 and the semiconductor laser chip 20 form a light emitting unit that emits laser light. An objective lens 50 that collects laser light is mounted on the housing 15 so as to be drivable via a two-dimensional actuator. Further, on the housing 15, a collimator lens 80 and a composite prism 35 are fixed as optical elements for guiding the laser light emitted from the semiconductor laser chip 20 to the objective lens. Further, on the housing 15, a photodetector 70 and a detection lens 60 are further fixed as a photodetector for detecting laser light.

Next, the structure of the pedestal 22, the method of joining the pedestal 22 and the semiconductor laser chip 20, and the method of joining the housing 15 and the pedestal 22 will be described with reference to FIG. The pedestal 22 is composed of a metal pedestal 23 made of copper having excellent electric conductivity and thermal conductivity, and a silicon semiconductor pedestal 24 formed on the metal pedestal 23. The pedestal 22 has a height that positions the light emitting portion of the semiconductor laser chip 20 at the height of the optical path of the optical head. The housing 22 is made of copper and is integrally formed with the metal pedestal 23 by cutting or die casting.

The semiconductor laser chip 20 uses a compound semiconductor such as gallium arsenide. In this embodiment, the semiconductor laser chip 20 is bonded to the metal pedestal 23 via the semiconductor pedestal 24 formed of silicon having a thermal expansion coefficient close to that of gallium arsenide. By doing so, the semiconductor laser chip generates heat when emitting light, and the semiconductor laser chip 2
The stress of the joint portion caused by the difference in thermal expansion between 0 and the pedestal 22 was relaxed, and the mechanical jointability was improved. Further, as the mechanical bondability is improved, peeling does not occur between the chip 20 and the pedestal 22, so that the electrical bondability is also improved.

The semiconductor laser chip 20 and the semiconductor pedestal 2
3, and the semiconductor pedestal 23 and the metal pedestal 24 were electrically, thermally, and mechanically joined by soldering. At this time, the order of joining may be either first, but the solder having a high melting point is selected as the solder used for the side to be joined first. In this embodiment, the metal pedestal 23 and the semiconductor pedestal 24 are first joined and the solder having the melting point T ₁ is used.
The melting point T ₂ of the solder used to join the semiconductor laser chip 20 with the semiconductor laser chip 20 is T ₂ <T ₁ . Further, the semiconductor pedestal 24 and the semiconductor laser chip 20 were joined with a solder having a temperature T such that T ₂ <T <T ₁ . By doing so, the metal pedestal 23 and the semiconductor pedestal 24, which have been previously joined, are not separated from each other, so that accurate alignment can be achieved. Then, in order to pass an electric current through the semiconductor laser chip 20, the conductor wire 25 was soldered on the upper surface of the semiconductor laser chip and the conductor wire 26 was soldered on the metal pedestal 23. As an example of the above-mentioned solder material, I
n, PbSn, AuSn, AuSi, etc. can be used. From these, an appropriate one is selected according to the melting point.

Next, the optical path of the optical head shown in FIG. 1 will be described. The linearly polarized laser beam 21 having an elliptical distribution emitted from the semiconductor laser chip 20 becomes a parallel beam by the collimator lens 80, and enters the compound prism 35. The composite prism 35 combines the functions of a shaping prism, a polarization beam splitter, and a quarter-wave plate. The laser beam 21 passes through the compound prism 35 and is shaped into a circle, and becomes circularly polarized by the action of the quarter-wave plate, and the objective lens 50 causes the laser beam 21 to be recorded on the recording film of the optical disc 300 installed on the optical head. Collected.

The beam reflected by the recording film again passes through the objective lens 50 and enters the compound prism 35, and becomes a linearly polarized light having a polarization direction different from that of the incident beam by 90 ° by the action of the quarter wavelength plate, and the polarized beam splitter It is guided to the detection lens 60 by a function and forms an image on the photodetector 70. For the photodetector 70, a photodiode of 4 divisions or 6 divisions is used.

The two-dimensional actuator 100 moves the objective lens 50 in the optical axis direction and the radial direction of the optical disc 300 to perform focus and tracking control. In such an optical system, a focus error detection includes an astigmatism method, a knife edge method, and the like, and a tracking error detection includes a three-beam method, a push-pull method, and a sample servo wobbling pit method.

This optical system is called an infinite optical system because the beam is parallel between the collimator lens 80 and the objective lens 50 and an infinite image forming system is used as the objective lens. The characteristic of the optical head of the infinite optical system is the optical disk 30.
The energy utilization efficiency of the beam irradiating to 0 is high, and an efficiency of 40% or more is generally obtained. For example, 30
When an mW semiconductor chip is used, it is possible to record or rewrite information by irradiating the recording film with a laser beam having a power of 12 mW or more. Therefore,
The optical head of this embodiment shown in FIG. 1 can be applied to a hole-type write-once type optical disc medium and a phase change type rewritable type optical disc medium.

Next, a method for assembling the optical head shown in FIG. 1 will be described. First, the pedestal 22 is formed on the housing 15 as described above, and the semiconductor laser chip 20 is soldered on the pedestal 22 as described above. After that, the copper wires 25 and 26 are soldered, the semiconductor laser 20 is oscillated, and laser light is emitted. At this time, the output of the semiconductor laser is checked to select defective products. For the non-defective semiconductor laser 20, the emitted laser light is used to cause the collimator lens 80, the compound prism 35, the objective lens 50, and the two-dimensional actuator, and the objective lens 50 causes the laser light to be the information recording surface of the optical disc medium. Fix so that it will be in focus.
Further, the detection lens 60 and the photodetector 70 are fixed so that the reflected laser light can be detected on the optical path where the laser light reflected by the optical disk medium is changed by the compound prism 35.

As described above, in the optical head of this embodiment, the semiconductor laser chip 20 generates heat by the semiconductor pedestal 24.
And, it is conducted through the metal pedestal 23, is transmitted to the housing 15, and is radiated by the housing 15. Therefore, since the housing 15 functions as a heat sink, it is not necessary to separately provide a heat sink, and the optical head can be made thin.
Further, since the two-dimensional actuator 100 has a structure that drives only the objective lens, it is possible to perform tracking control and focus control with a small driving force. Also,
Since the semiconductor pedestal 24 is used as the pedestal in contact with the semiconductor laser chip 20, no stress is applied to the semiconductor laser due to the difference in thermal expansion coefficient. Silicon semiconductor pedestal 2
No. 4 has a higher thermal conductivity than gallium arsenide, which is the material of the semiconductor laser 20, so that the semiconductor laser chip 20
The thermal conductivity between the metal base 23 and the metal base 23 is very good.

Further, in the above-described embodiment, it is easy to improve the bonding property by subjecting the bonding surface between the semiconductor pedestal 24 and the metal pedestal 23 to a treatment such as metallizing. As the semiconductor pedestal 24, SiC, diamond, BeO, CuW, AlN or the like may be used instead of silicon.

In this embodiment, the semiconductor laser chip 20 is bonded to the metal pedestal 23 via the semiconductor pedestal 24, but the semiconductor laser chip 20 may be directly bonded to the metal pedestal by soldering. In that case, the chip 20 and the metal pedestal 23
The difference in the coefficient of thermal expansion between
It is desirable to use a soft material such as. The housing 15 can also be made of an alloy such as aluminum or zinc. The metallic pedestal 23 may be made of a metal such as aluminum or zinc having excellent electric conductivity and thermal conductivity. The housing 15 and the metal pedestal 23 may be made of different materials and soldered.

Furthermore, although soldering is used to bond the semiconductor laser chip 20 onto the housing 15 in this embodiment, other electrical bonding methods such as silver brazing may be used. In addition to the laser chip 20, a photodetector for monitoring the output of the housing 15 and a drive circuit therefor, or a high-frequency current as a drive current for stabilizing the oscillation of the semiconductor laser are provided on the housing 15. It is also possible to form an oscillator or the like.

When a magneto-optical disc is used as the rewritable optical disc, the present invention can be applied to the light emitting portion, although the optical head of this embodiment has a different signal detection system.

Next, FIG. 16 shows an embodiment of an optical head having a structure having a hermetically sealing portion for hermetically sealing a semiconductor laser chip. The configuration of the optical system is the same as that of the embodiment shown in FIG. As the housing 15, one having a shape having a rising portion 15a was used. Semiconductor laser chip 20 with a light source output of 30 mW
Is soldered to a semiconductor pedestal 24 formed of silicon, and the semiconductor pedestal 24 is joined to a metal pedestal 23 formed on the housing 15. Semiconductor laser chip 20
The laser beam from is converted into parallel light by the collimator lens 80 fixed at a predetermined position by the collimator lens holder 81 and transmitted through the compound prism 35, the window glass 45 for encapsulation, and the objective lens 100 through the recording surface of the optical disc. Focused on top. The reflected light from the optical disk is the objective lens 50, the window glass 45, the composite prism 35.
After being transmitted, the light is guided to a photodetector by the same optical system as in FIG. 1 and detected.

Among these optical components, the semiconductor laser chip 20, the collimator lens 80, the composite prism 35, the detection lens, and the photodetector were fixed to the housing 15 made of aluminum. Furthermore, the rising portion 15a of the housing has a thickness of 0.3.
The window was covered with a mm window glass 45 and sealed. The window glass 45 was welded to the housing 15a by the low melting point glass 46. Dry nitrogen gas was enclosed in the sealed package. Thus, the rising portion 15a of the housing and the housing 1
A part of the bottom surface of the window 5 and the window glass 45 form a hermetically sealed portion.

A part of the window glass serves as a window portion through which the laser light passes. When the laser beam reflected by the window glass 45 returns to the semiconductor laser chip 20, noise is generated in the emission intensity. Therefore, an antireflection coating is applied to the portion of the window glass 45 through which the laser beam passes, and the reflectance is 0.5%. I made it small. The two-dimensional actuator 100 that supports and moves the objective lens 50 is fixed on the same housing 15. In this example, an objective lens having an effective diameter of 2 mm was used and the thickness of the optical head was 6 mm. Since an optical disk device needs to focus the laser beam to the diffraction limit, it is necessary for the window glass to pass through the laser beam without giving any aberration, and it is optically transparent to the laser light such as glass and sapphire. , A material with good flatness and no hygroscopicity is used.

FIG. 17 shows another embodiment of an optical head having a structure in which a semiconductor laser chip is sealed. The configuration of the optical system is the same as that of the embodiment shown in FIG. Semiconductor laser chip 2 of light source
0 is soldered to a semiconductor pedestal 24 formed of silicon, and the semiconductor pedestal 24 is joined to a metal pedestal 23 formed on the housing 15. The laser beam from the semiconductor laser chip 20 becomes parallel light by the collimator lens 80 and passes through the compound prism 35, and the objective lens 100
Are focused on the recording surface of the optical disc. The reflected light from the optical disk passes through the objective lens 50 and the compound prism 35, and then is guided to the photodetector by the same optical system as in FIG. 1 and detected. Moves while supporting the objective lens 50 2
The dimensional actuator 100 is fixed on the same housing 15.

The semiconductor laser chip 20 is enclosed by a hermetically sealed portion formed by a collimator lens 80 made of glass, a collimator lens holder 81 made of aluminum, and a part of the bottom surface of the housing 15. When assembling,
The collimator lens 80 is previously fixed to the collimator lens holder 81 with the low melting point glass 46, and the collimator lens holder 81 is moved and adjusted so that the collimator lens comes to a predetermined position with respect to the semiconductor laser chip 20.
The collimator lens holder was fixed to the housing 15 by laser welding, and the semiconductor laser chip 20 was sealed. The sealed package was filled with dry nitrogen gas.

By sealing the semiconductor laser in the hermetically sealed portion as shown in FIGS. 16 and 17, the semiconductor laser 20 can be protected from humidity and dust and the emission intensity can be stabilized.

FIG. 3 is an embodiment showing an optical head of a finite optical system constructed according to the present invention. The light emitting portion of the optical head shown in FIG. 3 is the same as that of the embodiment of FIG. 1, but the optical element for guiding the laser light emitted from the light emitting portion to the optical disk is different. A finite optical system widely used for a compact disc, which is a typical example of a read-only type optical disc, does not require a collimating lens, and thus has a simple optical head configuration. The semiconductor laser chip 20 is electrically bonded onto a pedestal 22 formed on the housing 15 of the optical head. Laser beam 21 emitted from semiconductor laser chip 20
Are divided into three by the diffraction grating 33. The beams at both ends are used for tracking signal detection.

The beam reflected by the half mirror 30 is guided to the objective lens 50 by the rising mirror 40 and focused on the optical disc 300. Optical disk 30
The beam reflected by 0 is reflected again by the objective lens 50 and the rising mirror 40, passes through the half mirror 30, and is guided to the detector 70 by the detection lens 60. The reproduction of recorded information and the focus and tracking error signals are detected. To be done. In such an optical system, the astigmatism method is used for focus error detection, and the three-beam method is used for tracking error detection. The focus and tracking control mechanism uses a two-dimensional actuator. Compared with the optical system of the optical head of the infinite optical system shown in FIG. 1, the number of parts is small and the feature is that it is possible to reduce the size and weight.

The optical head of the present invention is not limited to the read-only type, but can be used for a recordable optical disk by using a high-power semiconductor laser chip.

FIG. 4 shows an embodiment in which the present invention is applied to a magneto-optical head. The semiconductor laser chip 20, which is a light source for recording and reproducing, is fixed to a pedestal 22 formed on the housing 15 of the optical head so as to emit light, as shown in FIG. The linearly polarized laser beam 21 having an elliptical distribution emitted from the semiconductor laser chip 20 is
The collimator lens 80 forms a parallel beam, and the shaping prism 31 shapes it into a circular shape.
2. Transmitting through the polarization beam splitter 33, the objective lens 5
It is focused on the recording film on the optical disc 300 by 0.

Of the beam reflected by the recording film, the light containing the recorded information is reflected by the polarization beam splitter 33 because the plane of polarization is rotated by the Kerr effect, and the phase compensator 9 is used.
The light is transmitted through the 1/1/2 wave plate 90 and divided into two by the polarization beam splitter 34, and guided to the photodetectors 71 and 72 by the detection lenses 61 and 62, respectively, depending on the output difference between the two photodetectors. The information is played. Of the reflected light from the optical disk medium 300, the light that has passed through the polarization beam splitter 33 and is reflected by the half mirror 32 is guided to the photodetector 70 by the detection lens 60 and detected as a focus and tracking error signal.

In such an optical system, there are astigmatism method, knife edge method, etc. for focus error detection, and three beam method, push-pull method, wobbling pit method of sample servo, etc. are used for tracking error detection. A two-dimensional actuator 100 is used for focus and tracking control.

In the optical head shown in FIG. 4, information is rewritten on the optical disk medium by irradiating a laser beam to reverse the magnetization of the recording material. There are methods of modulating the optical output and methods of modulating the magnetic field as the method, but the description thereof will be omitted here because it departs from the contents of the present invention.

FIG. 5 shows the relationship between the beam diameter of the objective lens and the working distance. The conventional optical disk medium has a diameter of about 300 mm to 130 mm, and the substrate has a thickness of 1.2 mm. If the diameter of the optical disk is large, the surface contact becomes large. Therefore, if a working distance of 1 mm or more is secured in order to allow a surface runout of ± 0.5 mm, it is difficult to use an objective lens having a beam diameter of 4 mm or less.

By mounting an objective lens having a small beam diameter, the optical head can be miniaturized and thinned, and an optical disk device using the optical head can be miniaturized and thinned. In the present invention, the beam diameter can be reduced to 3.5 mm or less by thinning the optical disk substrate and reducing the amount of surface wobbling. That is, by setting the optical disk substrate to 1 mm or less, for example, 0.6 mm, the beam diameter can be 2 mm even when the working distance remains 1 mm. Further, by using an optical disc medium having a diameter of 90 mm or less, the amount of surface wobbling can be reduced substantially in proportion to the diameter of the optical disc medium.

Further, when the optical disc medium is enclosed in a transparent protective case and an optical system for injecting a laser beam through the transparent protective case is used, it is possible to prevent the objective lens from directly colliding with the rotating optical disc medium. Even if the working distance is further reduced, the reliability of the objective lens and the optical disk medium is maintained. For example, if the thickness of the substrate of the optical disk medium is 0.5 mm and the thickness of the transparent protective case is 0.3 mm, the optical system is the same as the case where the thickness of the optical disk substrate is 0.8 mm, so the beam diameter is 2 mm and the working distance is A 0.4 mm optical head can be realized. The thickness of the recordable optical head assembled with this configuration was 6 mm in the infinite optical system and 5 mm in the finite optical system, which was less than half that of the conventional optical head.

FIG. 6 is an embodiment showing the structure of a two-dimensional actuator suitable for use in the optical head of the present invention.
The movable part includes the objective lens 50, the counter weights 190, and 2.
It is composed of one focus coil 140 and four tracking coils 130. The movable portion is held by using two sets of leaf springs 110 from above and below, and is supported by the support portion 180. The magnetic circuit includes a magnet 150 and a yoke 160, and the magnetic flux generated by the magnetic circuit is the focus coil 140.
And the tracking coil 130 is penetrated.

The counterweight 190 has almost the same weight as the objective lens, and the center of gravity of the movable part, the center of rotation, and the center of support of the spring 110 are arranged coaxially. The propulsive force of this two-dimensional actuator is an electromagnetic force generated by passing a current through the focus coil and the tracking coil. The movable part moves independently by two propulsive forces.

That is, the focus control can be performed by the movement in the direction perpendicular to the paper surface, and the tracking control can be performed by the rotation movement around the support center point. Even if a small flexible actuator such as a flexible cable is used for power supply in a small two-dimensional actuator such as this actuator, the effect of its rigidity and weight on the movement of the two-dimensional actuator cannot be ignored and smooth movement is hindered. It is easy to damage the performance.
In the structure of the present invention, since the springs are conductors, two four springs can be used to feed each coil. This two-dimensional actuator is an optical head chassis 15
Attach it to and use it.

Here, the objective lens 50 has an effective beam diameter of 2
When the mm aspherical glass objective lens is used, its weight is about 70 mg, and the total weight of the movable portion is about 0.64 g. When a phosphor bronze having a plate thickness of 60 μm, a width of 90 μm, and a length of 10 mm from the support portion 180 to the support center point is used as the spring 110, the resonance frequency in the focus direction of the two-dimensional actuator is 23 Hz, and the resonance frequency in the tracking direction is 45 Hz. .. 80 μm diameter as wire for coil
The resistance when the number of turns of the focus coil is 90 and the number of turns of the tracking coil is 50 are connected in series using the polyurethane coated wire of No. 10 is 10Ω and 8Ω, respectively.

At this time, the thickness of the two-dimensional actuator is 5 m.
The thickness can be reduced to m, and the thickness can be reduced to about half that of the conventional one. The acceleration sensitivity of the two-dimensional actuator having such a configuration is 40 in both the focusing direction and the tracking direction.
G / A (G is gravitational acceleration) or more is obtained, and the maximum acceleration is 7 G or more. With an optical head equipped with this actuator, an optical disc with a diameter of 130 mm can be used for 3600 r
It was confirmed that focus and tracking control were possible at a high speed of pm or higher, and that it had performance equivalent to or better than conventional products. Further, the power supply voltage for driving the present two-dimensional actuator may be about 2 V, and since the movable part is lightweight, the power consumption is small, so that it can be sufficiently driven by a dry battery and is suitable for use in a portable optical disk device. ..

Examples of the optical disk medium suitable for the present invention are shown below.

FIG. 7 shows an embodiment showing the structure of an optical disk medium having a diameter of 65 mm using a thin substrate. In this optical disc medium, the optical disc 300 is built in a protective case 310, and the laser beam is slidable by a slidable protective cover 330 attached to the protective case 310 to open an optical path. Is irradiated. A magnetic chuck for attaching to the motor is attached to the optical disc 300. For the optical disc substrate, glass having a thickness of 0.6 mm, polycarbonate, and PMMA were used. By setting the diameter of the disk substrate to be 65 mm, the amount of surface wobbling was reduced to 1/2 compared with the conventional disk having a diameter of 130 mm even at the same surface wobbling angle. A PMMA plate was used for the case. The distance between the substrate and the case was 0.4 mm above and below. With this configuration, the surface wobbling amount of the optical disc 300 can be suppressed to ± 0.3 mm at the maximum.

In the present invention, the diameter of the optical disk is 65 mm, but the size can be changed as required. The smaller the diameter of the optical disc, the more suitable it is to apply the optical system of the present invention. For example, it could be applied to a disc of 50 mm or 25 mm. In addition, even for large-diameter discs, diameter 9
It has been found that the present invention is applicable to discs up to 0 mm.

As a recording material of the recording film 400, Proc.Soc.P
hoto-Opt.Inst.Eng. (SPIE), Vol. 1078, pp.
11-pp. 26, (1989).
A -Sb-Te based rewritable phase change recording material was used. Here, the power required for recording on the In-Sb-Te recording film was 10 mW on the recording surface. Other rewritable optical recording materials include Ge-Sb-Te system, In
-Se-Tl-based, In-Sb-Te-based, Sb-Te-based crystal-amorphous phase change recording materials, or Tb
A magneto-optical recording material such as a —Fe—Co type or a Gd—Fe—Co type can be used.

As the write-once type optical recording medium, an inorganic material based on Te or the like or an organic material such as cyanine or naphthalocyanine can be used. That is, any medium that can be reproduced or recorded and erased by laser light can be used as the medium of the present invention. As the read-only optical disc, it is also possible to use an optical disc substrate such as a compact disc or a video disc on which information is recorded in the form of concavities and convexities, and a reflective material such as Al or Au is formed on the surface thereof.

FIG. 8 shows an optical disk medium (hereinafter referred to as an optical disk i) incorporated in a transparent protection case of a credit card size.
(referred to as n-card). Optical disc 300
Is rotatably incorporated in the protective case 310. The outer shape of the protective case 310 is a credit card size for easy handling, and has a length of 84 mm, a width of 54 mm, and a thickness of 1.5 mm. The optical disk substrate 305 has a diameter of 49 mm and a thickness of 0.5.
mm glass substrate, PC substrate and PMMA substrate were used.
A PMMA plate was used for the case. The thickness of the light incident portion of the protective case 310 was 0.3 mm. Therefore, the sum of the thicknesses of the optical disc substrate 305 and the transparent protective case 310 is 0.8 mm, and an optical disc 300 having a corresponding diameter of 2 mm and a working distance of 0.4 mm is used.
It was confirmed that information can be recorded and reproduced in the range of 600 rpm to 3600 rpm. At this time, the surface wobbling amount of the optical disc 300 was ± 0.15 mm at the maximum.
In this embodiment, 320 is a magnet chuck for bonding the optical disc 300 to the motor.

As the format of the optical disc 300, two types of sample servo formats of 4-15 modulation and 8-9 modulation are used, and the number of sectors per track is 1.
6, the data area was in the range of 30 mm to 48 mm in diameter, and the storage capacity was 40 MB on one side. In this optical recording medium, the rotation speed was 3600 rpm, and the effective data transfer rate after error correction was 3.9 Mb / s. In addition to this, a continuous servo format of 2-7 modulation or the like can be used as the format.

Further, if the transparent protective case 310 is transparent only in the optical path of the laser beam, there is no practical problem even if it is opaque. The entire case may be made of a light transmissive material, or only the portion corresponding to the optical head may be made light transmissive, and the other case may be made of a material having no light transmissivity.

FIG. 9 shows an embodiment of an optical disk in-card capable of recording on both sides. In the credit card size transparent protective case, the first recording film 401 is formed.
The optical disk substrate 305 and the second optical disk substrate 306 on which the second recording film 402 is formed are rotatably built in so that the recording films are inside each other. Here, UV is used as the adhesive layer 405.
A resin and an epoxy resin were used. The capacity of this optical recording medium is 8 on both sides using the same format as in the embodiment of FIG.
It was set to 0 MB. The thickness of the optical disk in card was 2 mm.

FIG. 10 is an embodiment showing the structure of an optical disk device in which an optical disk medium and an optical head are combined.
The optical head 10 is attached to the course actuator 700 and is movable in parallel with the optical disc medium 350. These are built into the optical disk device chassis 800.
In this embodiment, a stepping motor having a thickness of 6 mm was used as the course actuator. The propulsive force of the course actuator was about 1N against the target of 2N.

The optical head 10 has a thickness of 6 mm and a weight of 25.
g, the average access time was about 100 ms. The thickness of the optical disk medium that can be recorded on one side as shown in FIG. 8 is 1.5 m.
m was used. The thickness of the optical disk device excluding the circuit is 10 mm, and the thickness of the optical disk device is 15 mm when the circuit is added, and it can be mounted on a laptop type or notebook type personal computer or a workstation. The thickness of this optical disk device can be reduced to 12 mm by advancing the circuit to LSI. Further, in this embodiment, an optical system having a beam diameter of 2 mm is used, but by changing this to an optical system having a beam diameter of 1.5 mm, the thickness of the optical head is 4.5 mm and the thickness of the optical disk device is increased. It turned out that it can be made 10 mm.

Also in this configuration, by increasing the thickness of the device by 0.5 mm, the double-sided recordable optical disk medium shown in FIG. 9 can be easily used. In this case, in order to record information on the back surface of the optical disc medium, the optical disc medium may be once taken out of the device, turned inside out, and inserted into the device.

With the configuration of the present optical disc device, recording / reproducing of the optical disc medium shown in FIG. 7 can be easily supported.

FIG. 11 shows an embodiment in which the embodiment of FIG. 10 is changed to a device capable of simultaneously recording and reproducing on both sides. As the optical disc medium 350, the one shown in FIG. 9 is used. The feature of this embodiment is that the first optical head 11 and the second optical head 12 shown in FIG. 17 are opposed to each other with the optical disk medium 350 interposed therebetween. It is attached to actuators 701 and 702. With this configuration, it is possible to record information on both sides without having to turn over the optical disc medium. In addition, since the first and second optical heads 11 and 12 can be driven independently, two types of information can be recorded / reproduced at the same time.

Further, the first and second optical heads 11 and 12
It is also possible to effectively double the data transfer rate by synchronously driving. A system for driving a plurality of recording / reproducing heads is already known as a floppy disk or a fixed magnetic disk system, and the same method can be applied to this apparatus. By using the same parts as the optical disk device of FIG. 10 in this configuration, the thickness of the device can be set to 20 mm, and it can be mounted on a laptop type or notebook type personal computer or a workstation. It was

This optical disk device can easily cope with recording / reproduction of the optical disk medium shown in FIG.

FIG. 12 is an embodiment showing a concrete structure of a recording / reproducing apparatus for an optical disk in-card. The optical disk in-card device 640 uses the optical disk in-card 350 as an optical memory medium containing the optical disk 300. Information is recorded / reproduced on / from the optical disc in-card 350 by rotating the optical disc 300 by the spindle motor 800 and irradiating a laser beam from the optical head 10. A course actuator 700 is used to access the optical head 10 to a predetermined information recording track. This optical disk in-card device has a thickness of 15 mm, a width of 65 mm and a length of 110 mm, and a storage capacity of 100 MB. This device is small in size, has a large capacity as compared with a magnetic hard disk device of the same size, and is capable of exchanging a memory medium.

FIG. 13 is a system configuration showing up to the data processing section of the optical disk device shown in FIG. In the figure, the medium and the drive unit are optical disc media 350,
It comprises an optical head 10, a spindle motor 800, and a course actuator 700. The drive microcomputer 600 controls the drive unit and performs signal processing. The drive microcomputer 600 includes a spindle servo 611, a focus servo 612, a tracking servo 613, and a co-operator as a mechanical system.
Each control of the actuator servo 614 is performed.

Further, the drive microcomputer 600 controls the laser drive unit 615 of the optical head to drive the preamplifier 61.
The servo error signal and the recorded information on the optical disk medium are reproduced via 6. The control microcomputer 605 sends an operation command to the drive microcomputer 600, and performs error correction on the recording signal to the optical disk medium or the reproduction signal from the optical disk medium. Further, the control microcomputer 605 also controls the interface when connecting to another system. The spindle motor support
The bob 611 controls the rotation speed of the spindle motor 800, and the CAV (Constant Angular Vel) is used for this rotation speed control.
ocity) control, CLV (Constant Linear Velocity) control, and MCLV (Modulated Constant Linear Veloci)
ty) control, etc., and can be appropriately selected according to the system.

Since the optical disk device of the present invention is small, lightweight, thin, and easy to handle, it can be installed in a stationary or laptop personal computer, a workstation, a word processor, a fax machine, Copy machine, television game machine, telephone, electronic still camera, video camera, portable music player, electronic system notebook, calculator, measuring instrument,
It is suitable for a system used as a common memory medium such as a visual presentation device. An example of such an optical memory system is shown in FIG. Each device can share an optical disk medium by using a compatible optical disk device.

FIG. 14 shows an embodiment in which the present invention is applied to a note type computer. The data processing unit of the notebook computer comprises a processor unit 601 and a semiconductor main memory 602, and a keyboard 610 and a display 620 are provided via a system bus 603.
However, a feature of the present invention is that a drive device 640 for an optical disk medium is further connected via an interface 630 of an optical disk in card. The optical disk medium 350 has a large capacity of about 100 MB despite its small outer shape of about 50 mm, and as a result, it is a note-type computer and a large-scale calculation process similar to that of a minicomputer. Is possible. Further, the optical disk medium 350 is removable from the drive device 640, which makes the system convenient to carry.

In FIG. 15, the optical disk medium 350 is connected to the notebook computer 670 and the terminal 673 of the large-scale computer 671.
It shows an example of using it as an interface. In FIG. 15, a large-scale computer 671 usually has a large-capacity memory 672 such as a fixed magnetic disk, and the network 67
It is connected to many terminals 673 through 5 and used.
Conventionally, such a system has a problem that it cannot be used without a terminal. By using the present invention, the optical disk medium 3 can be added to the notebook computer 670.
It is possible to use the same optical disc medium 350 as the memory of the terminal 673 of the large-scale computer while using 50. In this way, by sharing the optical disk medium 350 as the memory of the laptop computer 670 and the terminal 673 of the large-scale computer, it is possible to proceed with program creation and debugging even in a home without a terminal or a moving train. You can

[0074]

As described above, according to the present invention, it is possible to provide a thin optical head having a sufficient heat capacity and capable of coping with the heat generation of a large-capacity semiconductor laser, and an assembling method thereof. It is also possible to provide a thin and small write-once and rewritable information processing apparatus using such a thin optical head.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of an optical head of the present invention.

FIG. 2 is a perspective view showing a configuration of a light emitting unit of the optical head shown in FIG.

FIG. 3 is a perspective view showing the configuration of another embodiment of the optical head of the present invention.

FIG. 4 is an optical path diagram showing a configuration when the present invention is applied to a magneto-optical type optical head.

FIG. 5 is a diagram showing a relationship between a beam diameter of an objective lens and a working distance.

6A and 6B are a cross-sectional view and a top view showing a configuration of a two-dimensional actuator that can be used for the present invention.

FIG. 7A is a sectional view and FIG. 7B is a top view of an optical disk medium suitable for the present invention.

FIG. 8 (a) of an optical disk in card suitable for the present invention
Sectional drawing and (b) top view.

FIG. 9 is a double-sided recordable optical disc suitable for the present invention.
The (a) sectional view and the (b) top view of a card.

FIG. 10 is a block diagram of an example of an optical disk drive device of the present invention.

FIG. 11 is a block diagram of an example of an optical disk drive of the present invention.

FIG. 12 is a block diagram of an example of an optical disk drive of the present invention.

FIG. 13 is a block diagram showing a configuration of a control unit of the optical disk drive device of the present invention.

FIG. 14 is a device configuration diagram when the optical disk drive device of the present invention is mounted on a note type computer.

FIG. 15 is a device configuration diagram when the optical disk drive device and the optical disk medium of the present invention are used as a terminal of a large-scale computer and an interface memory of a note type computer.

16 is a configuration diagram of an example in which a hermetically sealing portion is provided in the optical head shown in FIG.

FIG. 17 is a configuration diagram of another example in which the optical head shown in FIG. 1 is provided with a hermetically sealed portion.

[Explanation of symbols]

10 ... Optical head, 15 ... Housing, 20 ... Semiconductor laser chip, 21 ... Laser beam, 22 ... Pedestal, 23 ... Metal pedestal, 24 ... Semiconductor pedestal, 25, 26 ... Conductive wire, 30 ... Half mirror, 33 ... Diffraction grating, 35 ... Compound prism, 40 ...
Startup Mira, 45 ... Window glass, 46 ... Low melting glass,
50 ... Objective lens, 60 ... Detection lens, 70 ... Photodetector, 80 ... Collimating lens, 81 ... Collimating lens holder, 100 ... Two-dimensional actuator, 300 ... Optical disc, 350 ... Optical disc in card, 613 ... Tracking servo, 612 ... Focus servo, 640 ...
Optical disk in card drive, 670 ... Notebook type computer, 700 ... Coarse actuator, 800 ... Optical disk device chassis.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Nobuyoshi Tsuboi 4026, Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture, Hitachi Research Institute, Ltd. (72) Inventor Saburo Yasukawa 4026, Kuji Town, Hitachi City, Ibaraki, Hitachi Corporation Hitachi Research Laboratory (72) Inventor Tetsuya Fushimi 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd.

Claims (16)

[Claims] 1. A light emitting section for emitting a laser beam on a substrate,
An objective lens unit that condenses the laser light, an optical element that guides the laser light to the objective lens, and a photodetector that detects the laser light are provided, and the laser light is condensed on the optical disc and reflected light. In the optical head for detecting the above, further comprising an actuator for driving the objective lens section on the base, the light emitting section is a pedestal section provided on the base, and a semiconductor laser chip fixed on the pedestal section. An optical head having: 2. The optical head according to claim 1, wherein the pedestal portion is a heat transfer member. 3. The optical head according to claim 2, wherein the pedestal portion and the base body are integrated. 4. The optical head according to claim 2, wherein the pedestal portion and the base body are separate bodies, and the pedestal portion is soldered to the base body. 5. The optical head according to claim 1, wherein the pedestal portion has a height that positions the semiconductor laser on the optical axis of the optical element. 6. The optical head according to claim 5, wherein the pedestal portion is made of metal. 7. The optical head according to claim 5, wherein the pedestal portion is made of semiconductor. 8. The pedestal portion according to claim 5, wherein the pedestal portion includes a first pedestal made of metal provided on the base body and a second pedestal made of semiconductor provided on the first pedestal. An optical head having the semiconductor chip fixed on the second pedestal. 9. The optical head according to claim 1, wherein the actuator drives the objective lens section at least in a direction perpendicular to an optical axis of the objective lens section. 10. The optical head according to claim 1, further comprising a hermetically sealing portion for hermetically sealing at least the semiconductor laser chip. 11. The optical head according to claim 10, wherein the hermetically sealing portion has a window portion transparent to the laser light. 12. The optical head according to claim 11, wherein the hermetically sealing portion uses a part of the optical element as the window portion. 13. The optical disc according to claim 1,
An optical head comprising: a transparent substrate having a thickness of 1 mm or less; and a recording medium on the transparent substrate, and focusing the laser light on the recording medium through the transparent substrate. 14. The optical head according to claim 1, wherein the effective diameter of the objective lens is 3.5 mm or less. 15. A light emitting section having a semiconductor laser chip and a pedestal section for holding the semiconductor laser chip on a base,
An objective lens unit that collects the laser light emitted from the light emitting unit, a photodetection unit that detects the laser light, and an actuator that drives the objective lens unit are provided. A method of assembling an optical head for detecting the following: first, the pedestal is provided on the base; then, the semiconductor laser chip is bonded onto the pedestal; and the objective lens unit is provided on the base. And a method of assembling an optical head, characterized in that an actuator is fixed, and the photodetector is fixed on the base. 16. An optical head according to any one of claims 1 to 9, a moving means for moving the optical head in a radial direction of the optical disc, a rotating means for rotating the optical disc, and a drive for an actuator of the optical head. An information processing apparatus comprising: an amount, a movement amount of the moving unit, and a control unit that controls a rotation speed of the rotating unit.