JP2003030883A - Optical pickup and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup of high packaging accuracy, stable quality and a small size. SOLUTION: The optical pickup has a light source unit 110 contg. a laser beam source 112 for emitting an illumination light beam for illuminating a recording medium, a diffraction grating 142 for splitting the reflected light beam reflected by the recording medium to a plurality of light beams by diffraction and separating these beams from the illumination light beam, a plurality of photodetectors 152 and 154 for detecting the light beams split by the diffraction grating 142, and a substrate 132 which is a base for holding the light source unit 110 and the photodetectors 152 and 154. The base 132 has UV transmittability and a holding member body 116 of the light source unit 110 is fixed to the under surface of the substrate 132 by a UV curing adhesive 162. The photodetectors 152 and 154 are fixed atop the substrate 132 by a UV curing adhesive 164.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for recording / reproducing information on / from an optical information recording medium, and more particularly to a small integrated optical pickup and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, a technique for reducing the size and cost of an optical pickup has been emphasized, and an optical pickup in which a plurality of elements are integrated has been developed.

Japanese Unexamined Patent Publication No. 6-5990 discloses one of optical pickups miniaturized by integration. The schematic structure is shown in FIG.

In FIG. 4, a semiconductor laser light source 702
The laser light beam emitted from the laser beam passes through the diffraction grating 704 and is focused on a recording medium (not shown) by a condenser lens (not shown).

The light beam modulated by the information reflected by the recording medium is diffracted by the diffraction grating 704 and split into two. The divided light beams respectively enter the light receiving elements 706 and 708 on the substrate 710, and the output signals thereof are detected as a focus error signal and a tracking error signal.

The substrate 710 on which the light receiving elements 706 and 708 are formed is a support base (block portion) 71 of a metal package.
2 is die-bonded onto the laser light source 702 and the base 7
Die-bonded directly on the side of 12 and cap 7
It is sealed in a small package by welding 14.

Further, Japanese Patent Laid-Open No. 6-76340 discloses an optical pickup which is a further development of the above-mentioned optical pickup. The schematic configuration is shown in FIG.

As shown in FIG. 5, the ceramic base 8
Light receiving element substrate 8 having light receiving elements 808 and 810 in 16
12 is mounted, and a laser diode (hereinafter referred to as L
D) 802 is installed. A cover 818 is provided on the ceramic base 816, and a transparent member having a hologram diffraction element 806 is mounted on the cover 818, whereby the LD 802 and the light receiving elements 808, 81 are provided.
It is a compact integrated pickup with 0 sealed.

A laser light beam emitted from the LD 802 is deflected upward by a 45 ° mirror surface 804 provided on a light receiving element, passes through a hologram diffractive element 806, and is condensed by an information recording medium by a condenser lens (not shown). (Not shown)
Is focused on.

The light beam reflected by the information recording medium is diffracted by the hologram diffraction element 806 and split into two beams, and the light receiving elements 808 and 81 on the light receiving element substrate 812.
It is incident on 0, and its output signal is detected as an error signal such as a focus error signal and a tracking error signal.

[0011]

In the optical pickup of FIG. 4, the LD 702 is die-bonded to the metal base 712. For die bonding, soldering or gold S
Since i-eutectic bonding is generally used, and in particular, the LD requires electrical connection between the mounting surface and the base, these methods are used.

That is, the LD is fixed at 200 ° C to 300 ° C.
It is performed by heating to about ℃ to melt the solder and cooling to solidify it, or after contact between the gold surface of the base and the Si of the LD is heated to about 300 to 350 ℃, if necessary. For example, ultrasonic waves are further applied to form and bond the eutectic alloy.

Therefore, even if the LD is correctly positioned before being fixed, it is difficult to fix the LD to a correct position because the expansion of the member caused by heating at a high temperature causes a displacement during the fixing work. It is also possible to try to detect and position the LD and the light receiving element by image processing during heating. However, since the air between the detection optical system and the member is also heated, and the resulting image fluctuates, it is difficult to perform accurate position detection.

Particularly, as the pickup is further downsized and the recording density of the medium is improved, the required mounting accuracy becomes higher, and especially the relative positional accuracy required between the LD and the light receiving element becomes extremely high. The above methods cannot meet such requirements.

The same applies to the optical pickup shown in FIG.
Since the LD 802 is mounted directly on the light receiving element substrate 812, a large amount of defects will occur if the LD mounting accuracy is low, but there is a limit to the LD mounting accuracy in a high temperature process such as soldering. It is difficult to handle high-density recording / playback.

Further, the LD is mounted on a light receiving element substrate made of Si, which has poor heat dissipation and thermal conductivity. On the other hand, the heat generated by the LD needs to be efficiently dissipated to the ceramic substrate that will be the package. For this reason, it is not suitable to mount the light receiving element substrate on the ceramic substrate with a material having a high thermal resistance such as an adhesive. Usually, the light receiving element substrate is mounted on the ceramic substrate by soldering or gold Si eutectic bonding. As a result, LD
Receives repeated heat stress. Excessive heat stress is L
The quality of D is deteriorated.

As described above, in the conventional integrated optical pickup, it is difficult to fix the LD and the light receiving element substrate with high positional accuracy at the time of manufacturing the optical pickup, so that the optical pickup can be further downsized and the information recording medium can be manufactured. It is difficult to deal with the improvement of recording density. In addition, the LD is likely to be subjected to excessive heat stress at the time of manufacture, and it is difficult to obtain an LD having stable quality.

An object of the present invention is to provide a small-sized optical pickup having high mounting accuracy and stable quality.

[0019]

The present invention is, in part, an optical pickup, which comprises a light source unit including a laser light source for emitting an illumination light beam for illuminating a recording medium, and a reflection reflected by the recording medium. A diffraction grating for dividing the light beam into a plurality of light beams by diffraction and separating the light beam from the illumination light beam, a plurality of light receiving elements for detecting the light beam divided by the diffraction grating, a light source unit and a light receiving element. It has a base for holding, at least the light source unit, the light receiving element and the base are integrated, the plurality of light receiving elements are located on substantially the same plane and near the laser light source, The pedestal is transparent to ultraviolet light, and allows ultraviolet light to pass through and irradiate the contact portion with the light receiving element and the contact portion with the light source unit. Element is fixed to the base by a UV-curing adhesive, the light source unit is fixed to the base by a UV-curing adhesive.

One aspect of the present invention is a method for manufacturing such an optical pickup, which comprises a step of holding a light source unit in contact with a base via an ultraviolet curing adhesive and holding the light receiving element with the ultraviolet curing adhesive. And a step of contacting and holding the base through the base, and a step of irradiating the ultraviolet curable adhesive through the base to cure the ultraviolet curable adhesive.

Another optical pickup of the present invention comprises a light source unit including a laser light source for emitting an illumination light beam for illuminating a recording medium, and a reflection light beam reflected by the recording medium is divided into a plurality of light beams by diffraction. A transparent flat plate on which a diffraction grating for separating the illumination light beam is formed, a light receiving element substrate on which a plurality of light receiving elements for detecting the light beam divided by the diffraction grating are formed, a light source unit and light receiving The light source unit, the light receiving element substrate, and the base are integrated, and the plurality of light receiving elements are located on substantially the same plane and near the laser light source. Further, a transparent flat plate is fixed to the light receiving element substrate, and the base is a substrate holding portion to which the light receiving element substrate is attached and a light source holding portion to which the light source unit is attached. The substrate holding portion has ultraviolet transparency, and it is possible for ultraviolet rays to pass through this and be radiated to the contact portion with the light receiving element substrate. Has a through hole capable of slidably accommodating the light source unit, and the light source holding portion has ultraviolet transparency, and ultraviolet rays pass through this to reach the contact portion with the light source unit. The light receiving element substrate is fixed to the substrate holding portion by an ultraviolet curing adhesive and the light source unit is fixed to the light source holding portion by an ultraviolet curing adhesive.

The present invention is also a method of manufacturing such an optical pickup, in which the step of inserting the light source unit into the through hole of the light source holding portion via the ultraviolet curable adhesive and the position along the optical axis of the light source unit. And the step of irradiating the ultraviolet curable adhesive with ultraviolet rays through the light source holder to cure the ultraviolet curable adhesive, and placing the light receiving element substrate on the substrate holder via the ultraviolet curable adhesive. And the step of positioning, and the step of irradiating the ultraviolet curable adhesive with ultraviolet rays through the substrate holding portion to cure the ultraviolet curable adhesive.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

First Embodiment As shown in FIG. 1, the integrated optical pickup of this embodiment has a light source unit 110 including a laser light source 112 which emits an illumination light beam for illuminating a recording medium, and a reflection on the recording medium. A diffraction grating 142 for dividing the reflected light beam into a plurality of light beams by diffraction and separating it from the illumination light beam, and a plurality of light receiving elements 15 for detecting the light beam divided by the diffraction grating 142.
2, 154, the light source unit 110 and the light receiving element 152,
And a substrate 132 which is a base for holding 154.

The light source unit 110 is a laser light source 11
It has a holding member 114 for holding 2. Holding member 1
Reference numeral 14 denotes a disc-shaped or flange-shaped holding member main body 11
6 and a conductive protrusion 118 protruding therefrom. The laser light source 112 is attached to the convex portion 118, and is mounted by, for example, solder.

The light source unit 110 further has pins 120 and 122 extending through the holding member main body 116, and these pins 120 and 122 are, for example, gold wires 124 and 126, respectively, for the laser light source 1.
12 and the convex portion 118 are electrically connected. In the light source unit 110, more preferably, the holding member 114 may be provided with a light receiving element for monitoring the light amount of the laser light source 112.

At least the light source unit 110, the light receiving elements 152 and 154, and the substrate 132 are integrated. The light receiving elements 152 and 154 are attached to the upper surface of the substrate 132, and the light source unit 110 has the holding member main body 116 of the holding member 114 attached to the lower surface of the substrate 132. In this integrated structure, the two light receiving elements 152 and 154 are located on substantially the same plane and near the laser light source 112.

The substrate 132 is transparent to ultraviolet rays,
Ultraviolet rays are transmitted through the light source unit 110 to contact the holding member body 116 and the light receiving elements 152 and 154.
It is possible to irradiate the contact area with. The holding member main body 116 of the light source unit 110 is fixed to the lower surface of the substrate 132 by the ultraviolet curable adhesive 162, and the light receiving elements 152 and 154 are fixed to the upper surface of the substrate 132 by the ultraviolet curable adhesive 164. Although not shown, the substrate 132 has electrodes and the like for taking out the outputs from the light receiving elements 152 and 154 to the outside.

The substrate 132 is made of an inorganic material having ultraviolet ray transparency. As such an inorganic material,
For example, Al ₂ O ₃ (alumina), SiO ₂ (silica),
Examples thereof include MgO, Ta ₂ O ₃ , ZrO _{2 and the} like, and mixtures thereof (for example, ceramics). Board 132
It is desirable that the dye does not contain a large amount of dyes or pigments that absorb or reflect ultraviolet rays. A suitable substrate 132 is
Ultraviolet transmittance of 1% or more and 10 at a thickness of 1 mm
It has a visible light transmittance of not more than%. For example, the substrate 13
2 is a plate material having a thickness of 1 mm and made of 96% alumina.

Since a material such as a glass flat plate has a too high transmittance of laser light, there is a possibility that light from the outside may enter and become stray light to hinder signal detection.
Not suitable for 32 materials.

The ultraviolet curable adhesives 162 and 164 have ultraviolet curability, but a suitable ultraviolet curable adhesive 1
The adhesives 62 and 164 may be adhesives that not only have ultraviolet curability but also exhibit other curing reactions such as heat curing, anaerobic curing, and moisture curing. For example, an adhesive such as an ultraviolet / anaerobic combined curing type, an ultraviolet / heat combined curing type, an ultraviolet moisture curing type, or a next-generation acrylic curing type (UVSGA) may be applied. For such an adhesive, the irradiation time of ultraviolet rays can be shortened as compared with an adhesive having only ultraviolet curability.

This optical pickup is assembled as follows.

First, the ultraviolet curing adhesive 162 is applied to the upper surface of the flange-shaped holding member main body 116 of the holding member 114, and the upper surface of the holding member main body 116 and the lower surface of the substrate 132 are aligned. That is, the holding member main body 116 is held in contact with the substrate 132 via the ultraviolet curable adhesive 162. Then, ultraviolet rays are applied from above the substrate 132 to the substrate 132.
The UV curable adhesive 162 is irradiated through the UV curable adhesive 162 to cure the UV curable adhesive 162.

Next, an ultraviolet curable adhesive 164 is applied to the upper surface of the substrate 132 to attach the light receiving elements 152 and 154 to the substrate 1.
Place it on the upper surface of 32. That is, the light receiving elements 152, 15
4 is held in contact with the substrate 132 via the ultraviolet curable adhesive 164. Further, the positions of the light receiving elements 152 and 154 with respect to the laser light source 112 are adjusted. At this time, the members and environment are at room temperature, and positioning by image processing or the like is effective. Subsequently, the ultraviolet curable adhesive 164 is irradiated with ultraviolet rays from below the substrate 132 through the substrate 132 to cure the ultraviolet curable adhesive 164.

After that, the light receiving elements 152 and 154 and the substrate 1
The 32 electrodes are electrically connected, and the diffraction grating 142 is attached through a window or a cap with a hole to complete the pickup.

This optical pickup operates simply as follows.

The light beam emitted from the laser light source 112 passes through the diffraction grating 142 and is emitted to the outside of the optical pickup. Although not shown in the figure, the light beam emitted from the optical pickup is converted into a parallel light beam by the collimator lens, is deflected by the deflection mirror, is condensed by the objective lens, and illuminates the information recording medium.

The light beam containing the information reflected by the information recording medium reaches the diffraction grating 142 via the objective lens, the deflection mirror and the collimating lens, and is diffracted by the diffraction grating 142 to generate two light beams, that is, +1. It is divided into a secondary light beam and a −1st order light beam. The + 1st-order light beam and the -1st-order light beam are incident on the light receiving elements 152 and 154, respectively.

The light receiving elements 152 and 154 output an electric signal according to the light quantity of the incident light beam, and the electric signal is processed by an external circuit, and based on this, an information reproduction signal, a focus error signal, and a tracking error signal. Is detected.

In the optical pickup of this embodiment, the light source unit 110 and the light receiving element 1 are made of an ultraviolet curable adhesive.
Since the members 52 and 154 are fixed to the substrate 132, these members are not heated to a high temperature during mounting, and therefore, positional displacement due to thermal expansion does not occur between these members.
Therefore, the light source unit 110 and the light receiving elements 152 and 154
Can be mounted on the substrate 132 with high positional accuracy.

Further, the laser light source 11 which is weak against heat stress
Since 2 is hard to be subjected to heat stress, an optical pickup of stable quality in which the laser light source 112 is hardly damaged during mounting can be obtained.

Further, since the substrate 132 is made of an inorganic material and has little expansion due to heating, the optical pickup of this embodiment can operate stably over a wide temperature range. In particular, the substrate made of alumina has a good thermal conductivity, and thus has an advantage that the heat of the laser light source can be quickly released. The adhesive layer is very thin, and the dimensional change of the adhesive layer due to the temperature change can be sufficiently ignored.

In this embodiment, the substrate 132 is irradiated with ultraviolet rays from the side opposite to the surface coated with the ultraviolet curable adhesive, but it is the same as the surface coated with the ultraviolet curable adhesive. You may irradiate from the side. In this case, it is known that the ultraviolet light diffusely reflected inside the substrate sufficiently cures the ultraviolet curable adhesive.

Second Embodiment As shown in FIG. 2, the integrated optical pickup of the present embodiment has a light source unit 210 including a laser light source 212 which emits an illumination light beam for illuminating a recording medium, and a reflection on the recording medium. A transparent flat plate 244 having a diffraction grating 242 for dividing the reflected light beam into two light beams by diffraction and separating the reflected light beam from the illumination light beam.
And a light receiving element substrate 256 having two light receiving elements 252 and 254 for detecting the light beam divided by the diffraction grating 242, a light source unit 210 and a light receiving element substrate 256.
And a base 230 for holding.

The light source unit 210, the base 230, the transparent flat plate 244, and the light receiving element substrate 256 are integrated, and the light receiving elements 252 and 254 are located on substantially the same plane, both of which are located near the laser light source 112. is doing.

The light source unit 210 includes a laser light source 21.
It has a holding member 214 that holds two. Holding member 2
Reference numeral 14 denotes a disc-shaped or flange-shaped holding member main body 21.
6 and a conductive protrusion 218 protruding therefrom. The convex portion 218 may be a separate member made of a material having good thermal conductivity, or may be integrally formed with the holding member main body 216 by pressing or the like. The laser light source 212 is attached to the convex portion 218, and is mounted by, for example, solder.

The light source unit 210 further has pins 220 and 222 extending through the holding member main body 216, and these pins 220 and 222 are, for example, gold wires 224 and 226, respectively.
12 and the convex portion 218 are electrically connected. In the light source unit 210, more preferably, a light receiving element for monitoring the light amount of the laser light source 212 may be provided on the holding member 214.

The base 230 has a substrate holding portion 232 to which the light receiving element substrate 256 is attached and a light source holding portion 234 to which the light source unit 210 is attached. The substrate holding part 232 and the light source holding part 234 are separate members, and may be fixed by adhesion or integrally molded. The light source holding portion 234 has a through hole that can slidably accommodate the light source unit 210 in the space inside thereof. The substrate holding portion 232 is the convex portion 2 of the light source unit 210.
It has a through hole through which 18 can pass. Further, the light receiving element substrate 256 also has a through hole inside which the laser light source 112 can be arranged.

The substrate holding portion 232 is transparent to ultraviolet rays, and allows ultraviolet rays to pass through and irradiate the contact portion with the light receiving element substrate 256. The light receiving element substrate 256 is fixed to the upper surface of the substrate holding portion 232 with an ultraviolet curing adhesive 264. Substrate holding section 232
(Not shown) has electrodes and the like for taking out the outputs from the light receiving elements 252 and 254 to the outside. Further, the light source holder 234 is transparent to ultraviolet rays, which allows ultraviolet rays to pass through and irradiate the contact portion with the light source unit 210. Light source unit 210
The holding member main body 216 is fixed inside the through hole of the light source holding portion 234 by the ultraviolet curable adhesive 262.

The substrate holder 232 and the light source holder 234 are
It is composed of an inorganic material having ultraviolet transparency. Examples of such an inorganic material include Al ₂ O ₃ (alumina), SiO ₂ (silica), MgO, Ta ₂ O ₃ and ZrO ₂
And mixtures thereof (for example, ceramics). It is desirable that the inorganic material forming the substrate holding part 232 and the light source holding part 234 does not contain a large amount of dyes or pigments that absorb or reflect ultraviolet rays.

Suitable substrate holder 232 and light source holder 23
No. 4 has an ultraviolet transmittance of 1% or more and a visible light transmittance of 10% or less in a thickness of 1 mm. For example, the substrate holding portion 232 is a plate material having a thickness of 1 mm and 96% alumina. The light source holding portion 234 is a plate material having a thickness of 1.5 mm and having a through hole formed by dry pressing and having 96% alumina.

The UV-curing adhesives 262 and 264 have UV-curing properties, but are suitable UV-curing adhesives 2.
The adhesives 62 and 264 may be adhesives that have not only ultraviolet curability but also other curing reactions such as heat curing, anaerobic curing, and moisture curing. For example, an adhesive such as an ultraviolet / anaerobic combined curing type, an ultraviolet / heat combined curing type, an ultraviolet moisture curing type, or a next-generation acrylic curing type (UVSGA) may be applied. For such an adhesive, the irradiation time of ultraviolet rays can be shortened as compared with an adhesive having only ultraviolet curability.

A transparent flat plate such as a glass flat plate 244 is fixed to the upper surface of the light receiving element substrate 256 by adhesion.
The glass flat plate 244 cooperates with the holding member main body 216 of the light source unit 210, and the light source holding portion 234 and the substrate holding portion 2
The space defined by 32 and the through hole of the light receiving element substrate 256 is sealed. That is, the laser light source 212 is sealed. The inside of this sealed space is replaced with an inert gas such as dry nitrogen as necessary.

This optical pickup is assembled as follows.

First, the semiconductor laser chip (LD) 212 which is a laser light source is mounted on the convex portion 218 of the holding member 214 by soldering. The semiconductor laser chip 212 may be mounted directly on the holding member or may be mounted via a submount provided with electrodes.

For example, the substrate holder 232 and the light source holder 23
Reference numeral 4 denotes separate members, which are fixed by adhesion by aligning the positions of the respective through holes. For bonding the substrate holding portion 232 and the light source holding portion 234, it is preferable to use an adhesive having an ultraviolet curability.

Next, the holding member main body 216 is attached to the light source holding portion 2.
UV curable adhesive 262 is formed on the entire inner peripheral surface of the through hole 34.
Is applied and the holding member main body 216 of the light source unit 210 is inserted into the through hole, so that the holding member main body 21
6 through the UV-curable adhesive 262 to hold the light source 23
4 and hold.

The holding member main body 216 can slide in the through hole of the light source holding portion 234. Therefore, when the Z axis is set parallel to the insertion direction of the holding member body 216, the light source unit 21
The position of 0 is adjustable along the Z axis, in other words, the position along the optical axis, and the direction around the Z axis is also adjustable.

The Z-axis position of the holding member 214 is adjusted so that the height of the light emitting end surface of the semiconductor laser chip 212 with respect to the upper surface of the substrate holding portion 232 becomes a suitable value. Further, the orientation of the holding member 214 about the Z axis is adjusted so that the orientation of the semiconductor laser chip 212 about the Z axis is suitable for the outer shape of the substrate of the substrate holding unit 232.

Subsequently, ultraviolet rays are applied to the ultraviolet curable adhesive 264 through the light source holder 234 to cure the ultraviolet curable adhesive 264. The ultraviolet rays are preferably emitted from the side of the light source holding unit 234, but may be emitted from below, or may be emitted from above through the substrate holding unit 232.

Next, the ultraviolet curing adhesive 264 is applied to the upper surface of the substrate holding portion 232, and the light receiving element substrate 256 is placed on the upper surface of the substrate holding portion 232. That is, the light receiving element substrate 256 is held in contact with the substrate holding portion 232 via the ultraviolet curable adhesive 264. At this time, the semiconductor laser chip 212 is arranged inside the through hole of the light receiving element substrate 256. Light receiving elements 252 and 2 on the light receiving element substrate 256
The position of the light receiving element substrate 256 is adjusted so that the relative positional relationship between 54 and the light emitting point of the semiconductor laser chip 212 becomes appropriate.

Subsequently, ultraviolet rays are passed from below the substrate holding portion 232 through the substrate holding portion 232 and the ultraviolet curable adhesive 26.
4 is irradiated to cure the ultraviolet curable adhesive 264.
As a result, the light receiving element substrate 256 is fixed to the substrate holding portion 232.

After that, an ultraviolet curing adhesive is applied to the upper surface of the light receiving element substrate 256, and the glass (or quartz) flat plate 244 having the diffraction grating 242 is placed. Further, the position of the glass flat plate 244 is adjusted so that the diffraction grating 242 is located at a suitable position with respect to the light receiving element substrate 256. It is more preferable that the light receiving element substrate 256 and the glass flat plate 244 are provided with alignment marks in advance.

Subsequently, ultraviolet rays are applied to the ultraviolet curable adhesive through the glass plate 244 to cure it. As a result, the glass flat plate 244 is fixed to the light receiving element substrate 256, and the optical pickup is completed.

This optical pickup operates in the following simple way.

The light beam emitted from the semiconductor laser chip 212 passes through the diffraction grating 242 and is emitted to the outside of the optical pickup. Although not shown in the figure, the light beam emitted from the optical pickup is converted into a parallel light beam by the collimator lens, is deflected by the deflection mirror, is condensed by the objective lens, and illuminates the information recording medium.

The light beam containing the information reflected by the information recording medium reaches the diffraction grating 242 through the objective lens, the deflection mirror and the collimating lens, and is diffracted by the diffraction grating 242, whereby two light beams, that is, +1. It is divided into a secondary light beam and a −1st order light beam. The + 1st-order light beam and the -1st-order light beam are incident on the light receiving elements 252 and 254, respectively.

The light receiving elements 252 and 254 output an electric signal according to the light quantity of the incident light beam, and the electric signal is processed by an external circuit, and based on this, an information reproduction signal, a focus error signal, and a tracking error signal. Is detected.

In the optical pickup according to this embodiment, the light source unit 210 and the base 230 are made of an ultraviolet curable adhesive.
Since the light receiving element substrate 256 and the glass flat plate 244 are fixed to each other, these members are not heated to a high temperature at the time of mounting, and therefore the positional displacement due to thermal expansion does not occur between these members. Therefore, the light source unit 210 and the light receiving element substrate 256 can be mounted with high positional accuracy.

Further, since the semiconductor laser chip 212, which is vulnerable to heat stress, is less likely to be subjected to heat stress, damage to the semiconductor laser chip 212, that is, deterioration in quality is less, and therefore an optical pickup of stable quality can be obtained.

Particularly in this embodiment, the light source unit 210
Since the position of the semiconductor laser chip 212 along the Z-axis can be adjusted during mounting,
The height positional relationship between the light receiving elements 252 and 254 can be positioned with high accuracy. That is, in the first embodiment, the relative heights of the laser light source 112 and the light receiving elements 152 and 154 mainly depend on the thickness of the substrate 132, and the adjustment thereof requires polishing or proper selection of the substrate 132. In Although,
In this embodiment, since the relative heights of the semiconductor laser chip 212 and the light receiving elements 252 and 254 can be adjusted without performing such an operation, the optical pickup can be manufactured at low cost.

As the holding member 214, the one having the same shape as that of a commercially available LD stem can be used as it is. Particularly, since existing equipment can be used for mounting a laser light source, it can be produced at a low cost. It is possible.

Further, the substrate holder 232 and the light source holder 23
Since 4 is made of an inorganic material and has little expansion due to heating,
The optical pickup of this embodiment can operate stably over a wide temperature range. In particular, the alumina substrate holder 232 and the light source holder 234 have high thermal conductivity and can quickly release the heat generated by the semiconductor laser chip 212. When the holding member main body 216 of the light source unit 210 is thin and thus the contact area with the light source holding portion 234 is insufficient and the heat radiation performance of the heat generated from the laser light source 212 is insufficient, the holding member main body 216 and the light source holding portion 234. It is advisable to secure heat dissipation by arranging a heat conductive adhesive on or by adding a metal plate bridging the two.

Third Embodiment The integrated optical pickup of this embodiment is an optical pickup compatible with the magneto-optical recording system, and its basic configuration is similar to that of the second embodiment. The structure of the integrated optical pickup of this embodiment is shown in FIG. In FIG. 3, the members indicated by the same reference numerals in the last two digits as those in FIG. 2 are substantially the same members.

As shown in FIG. 3, the integrated optical pickup of this embodiment includes a light source unit 310 including a laser light source 312 that emits an illumination light beam that illuminates a recording medium.
And a prism 372 including a polarization beam splitter 374 for splitting the reflected light beam reflected by the recording medium.
And a transparent plate 34 having a diffraction grating 342 for splitting the light beam transmitted through the polarization beam splitter 374 into two light beams by diffraction and separating the light beam from the illumination light beam.
4, an anisotropic crystal plate 378 for splitting the light beam reflected by the polarization beam splitter 374 into two beams according to the polarization, and two light receiving for detecting the light beam split by the diffraction grating 342. A light receiving element substrate 382 having a light receiving element group 380 for magneto-optical detection for detecting a light beam divided by the elements 352 and 354 and the anisotropic crystal plate 378, and a substrate holding the light source unit 310 and the light receiving element substrate 382. And a stand 330.

The light source unit 310, the base 330, the transparent flat plate 344, the prism 372, the anisotropic crystal plate 378 and the light receiving element substrate 382 are integrated, and the light receiving elements 352 and 352 are integrated.
354 is located on substantially the same plane, and these are both located near the laser light source 112.

The light source unit 310 includes a laser light source 31.
It has a holding member 314 for holding 2. Holding member 3
Reference numeral 14 denotes a disc-shaped or flange-shaped holding member main body 31.
6 and a conductive protrusion 318 protruding therefrom.

The light source unit 310 further has pins 320 and 322 extending through the holding member body 316, and these pins 320 and 322 are, for example, gold wires 324 and 326, respectively.
12 and the convex portion 318 are electrically connected.

The base 330 has a substrate holding portion 332 to which the light receiving element substrate 382 is attached and a light source holding portion 334 to which the light source unit 310 is attached. The light source holder 334 has a light source unit 31 inside the space inside.
It has a through hole capable of accommodating zero. The substrate holding portion 332 has a through hole through which the convex portion 318 of the light source unit 310 can pass. In addition, the light receiving element substrate 382
Also has a through hole inside which the laser light source 112 can be arranged.

The substrate holding portion 332 is transparent to ultraviolet rays, and allows ultraviolet rays to pass through and irradiate the contact portion with the light receiving element substrate 382. The light receiving element substrate 382 is fixed to the upper surface of the substrate holding portion 332 by an ultraviolet curable adhesive 364. Substrate holding unit 332
Although not shown, has electrodes and the like for taking out the outputs from the light receiving elements 352 and 354 and the photomagnetic detection light receiving element group 380 to the outside. In addition, the light source holder 334
Has a transparency to ultraviolet rays, and allows ultraviolet rays to pass through and irradiate the contact portion with the light source unit 310. Holding member main body 316 of light source unit 310
The light source holder 334 is formed by the ultraviolet curable adhesive 362.
Is fixed inside the through hole.

The substrate holder 332 and the light source holder 334 are
Inorganic material having ultraviolet transparency, for example, Al ₂ O ₃ (alumina), SiO ₂ (silica), MgO, Ta ₂ O ₃ , Z
It is composed of rO ₂ or the like, or a mixture thereof (for example, ceramics). In this embodiment, the substrate holder 3
32 and the light source holder 334 are both made of a white sintered body of 96% alumina.

The ultraviolet curable adhesives 362 and 364 have ultraviolet curability, but a suitable ultraviolet curable adhesive 3
The adhesives 62 and 364 may be adhesives that have not only ultraviolet curability but also other curing reactions such as heat curing, anaerobic curing, and moisture curing.

A transparent flat plate such as a glass flat plate 344 is fixed to the upper surface of the light receiving element substrate 382 by adhesion.
The glass flat plate 344 cooperates with the holding member main body 316 of the light source unit 310, and the light source holding portion 334 and the substrate holding portion 3 are provided.
The space defined by 32 and the through hole of the light receiving element substrate 382 is sealed. That is, the laser light source 312 is sealed. The inside of this sealed space is replaced with an inert gas such as dry nitrogen as necessary.

The prism 372 is, in addition to the polarization beam splitter 374, a mirror for reflecting the light beam reflected by the polarization beam splitter 374 toward the photomagnetic detection light receiving element group 380 formed on the light receiving element substrate 382. It has 376. The prism 372 is fixed to the anisotropic crystal plate 378 by adhesion, and
78 is also fixed to the light receiving element substrate 382 by adhesion.

This optical pickup is assembled as follows.

First, the semiconductor laser chip (LD) 312, which is a laser light source, is mounted on the convex portion 318 of the holding member 314 by soldering. Subsequently, for example, the substrate holding portion 332 and the light source holding portion 334, which are separate members, are fixed by adhesion by aligning the positions of the through holes.

Next, the holding member main body 316 is attached to the light source holding portion 3.
UV curable adhesive 362 on the entire inner peripheral surface of the through hole of 34.
Is applied and the holding member main body 316 of the light source unit 310 is inserted into the through hole, so that the holding member main body 31
6 through the UV curable adhesive 362, the light source holder 33
4 and hold.

The holding member main body 316 has a light source holding portion 334.
Can slide in the through hole of the semiconductor laser chip 3
The position of 12 along the optical axis and the direction around the optical axis can be adjusted. The height of the light emitting end surface of the semiconductor laser chip 312 is adjusted with respect to the upper surface of the substrate holding portion 332, and further the orientation of the semiconductor laser chip 312 around the optical axis is adjusted with respect to the outer shape of the substrate of the substrate holding portion 332.

Subsequently, ultraviolet rays are applied to the ultraviolet curing adhesive 364 through the light source holder 334 to cure the ultraviolet curing adhesive 364. The ultraviolet rays are preferably emitted from the side of the light source holding unit 334, but may be emitted from the lower side or further from the upper side through the substrate holding unit 332.

Next, an ultraviolet curing adhesive 364 is applied to the upper surface of the substrate holding portion 332, and the light receiving element substrate 38 is applied thereon.
2 is placed, and the light receiving element substrate 382 is placed on the substrate holding portion 332 so that the semiconductor laser chip 312 is arranged in the through hole of the light receiving element substrate 382. That is, the light receiving element substrate 382 is held in contact with the substrate holding portion 332 via the ultraviolet curable adhesive 364. The relative positions of the light receiving elements 352 and 354 of the light receiving element substrate 382 and the semiconductor laser chip 312 are adjusted.

Subsequently, ultraviolet rays are passed from below the substrate holding portion 332 through the substrate holding portion 332 and the ultraviolet curable adhesive 36.
4 is irradiated to cure the ultraviolet curable adhesive 364.
As a result, the light receiving element substrate 382 is fixed to the substrate holding portion 332.

After that, an ultraviolet curing adhesive is applied to the upper surface of the light receiving element substrate 382, and the glass flat plate 344 having the diffraction grating 342 is placed. Further, the light receiving element substrate 382
The position of the glass flat plate 344 is adjusted so that the diffraction grating 342 comes to a suitable position.

Subsequently, ultraviolet rays are applied to the ultraviolet ray curable adhesive through the glass plate 344 to cure it. As a result, the glass flat plate 344 is fixed to the light receiving element substrate 382.

Further, an ultraviolet curable adhesive is applied to the upper surface of the anisotropic crystal plate 378, and the prism 372 is fitted to this. Then, the ultraviolet curable adhesive is irradiated with ultraviolet rays to cure it. As a result, the prism 372 and the anisotropic crystal plate 378 are fixed to each other. This prism 37
2 and the anisotropic crystal plate 378 are usually fixed by the prism 37.
2 is placed below.

Subsequently, an ultraviolet curing adhesive is applied to the upper surface of the light receiving element substrate 382, and the anisotropic crystal plate 378 integrated with the prism 372 is placed on the appropriate position. Then, the ultraviolet curable adhesive is irradiated with ultraviolet rays to cure it. As a result, the prism 372 and the anisotropic crystal plate 378 are fixed to the light receiving element substrate 382, and the optical pickup is completed.

To put it simply, this optical pickup operates as follows.

The light beam emitted from the semiconductor laser chip 312, after passing through the diffraction grating 342, passes through the polarization beam splitter 374 except for a part thereof and is emitted to the outside of the optical pickup. Although not shown in the figure,
The light beam emitted from the optical pickup is converted into a parallel light beam by the collimator lens, is deflected by the deflection mirror, is condensed by the objective lens, and illuminates the information recording medium.

A part of the light beam is reflected by the polarization beam splitter 374, and the reflected light is used for the light quantity monitor of the semiconductor laser chip 312.

The light beam containing the information reflected by the information recording medium reaches the polarization beam splitter 374 through the objective lens, the deflection mirror and the collimating lens, and is split into two light beams.

The light beam reflected by the polarization beam splitter 374 is subsequently reflected by the mirror 376 and is incident on the anisotropic crystal plate 378. Inside the anisotropic crystal plate 378, two light beams are emitted according to the polarization component. It is split into light beams. These two light beams are used as a photo-optical detection light-receiving element group 38.
It is incident on 0. The magneto-optical detection light-receiving element group 380 outputs an electric signal according to the light quantity of the incident light beam, and the electric signal is processed by an external circuit to detect the magneto-optical signal.

On the other hand, the light beam transmitted through the polarization beam splitter 374 reaches the diffraction grating 342 and is diffracted by the diffraction grating 342, so that the two light beams, that is, +
It is divided into a primary light beam and a −1st order light beam. The + 1st-order light beam and the -1st-order light beam are received by the light receiving elements 352 and 352, respectively.
354 is incident. The light receiving elements 352 and 354 output an electric signal according to the light quantity of the incident light beam, and the electric signal is processed by an external circuit to detect a focus error signal and a tracking error signal.

In the optical pickup corresponding to the magneto-optical recording / reproducing according to the present embodiment, the light source unit 310, the base 330, the light receiving element substrate 382, the glass flat plate 344, and the anisotropic crystal plate 378 are formed by the ultraviolet curing adhesive. Prism 37
Since the two are fixed to each other, the light source unit 310 and the light receiving element substrate 382 can be mounted with high positional accuracy.

Further, it is possible to obtain a stable quality optical pickup in which the semiconductor laser chip 312 is hardly damaged during mounting.

Particularly in this embodiment, the light source unit 310 is used.
Since the position of the semiconductor laser chip 312 along the optical axis can be adjusted during mounting, a highly accurate adjusted optical pickup can be obtained at low cost.

Although some embodiments have been concretely described with reference to the drawings, the present invention is not limited to the above-mentioned embodiments and is carried out without departing from the scope of the invention. Includes all implementations.

For example, in the optical pickup of the above-described embodiment, even if the optical beam emitted from the optical pickup is applied to a finite optical system that narrows down the beam directly with the objective lens, it is once converted into a parallel light beam by the collimating lens and then the objective beam is obtained. It may be applied to an infinite optical system that narrows down with a lens.

[0107]

According to the present invention, a small-sized optical pickup having high mounting accuracy and stable quality is provided.

[Brief description of drawings]

FIG. 1 shows a configuration of an integrated optical pickup according to a first embodiment of the present invention.

FIG. 2 shows a configuration of an integrated optical pickup according to a second embodiment of the present invention.

FIG. 3 shows a configuration of an integrated optical pickup according to a third embodiment of the present invention.

FIG. 4 shows a configuration of a conventional integrated optical pickup disclosed in Japanese Patent Laid-Open No. 6-5990.

FIG. 5 shows a configuration of a conventional integrated optical pickup disclosed in Japanese Patent Laid-Open No. 6-76340.

[Explanation of symbols]

110 light source unit 112 laser light source 132 substrate 142 diffraction grating 152,154 Light receiving element 162 UV curable adhesive 164 UV curable adhesive

Claims (9)

[Claims] 1. A light source unit including a laser light source which emits an illumination light beam for illuminating a recording medium, and for separating a reflected light beam reflected by the recording medium into a plurality of light beams by diffraction and separating them from the illumination light beam. It is equipped with a diffraction grating, a plurality of light receiving elements for detecting the light beam split by the diffraction grating, and a light source unit and a base holding the light receiving element, and at least the light source unit, the light receiving element, and the base. The multiple light-receiving elements are located on almost the same plane and near the laser light source, and the base is UV-transmissive. It is possible to irradiate the contact part with the element and the contact part with the light source unit, the light receiving element is fixed to the base with an ultraviolet curing adhesive, and the light source unit is It is fixed to the base by a line-curable adhesive, the optical pickup. 2. The base is mainly Al ₂ O ₃ , SiO ₂ and Mg.
The optical pickup according to claim 1, wherein the optical pickup is made of one of O and Ta ₂ O ₃ or a mixture thereof. 3. The optical pickup according to claim 2, wherein the base has a UV transmittance of 1% or more and a visible light transmittance of 10% or less in a thickness of 1 mm. 4. A light source unit including a laser light source that emits an illumination light beam for illuminating a recording medium, and for separating a reflected light beam reflected by the recording medium into a plurality of light beams by diffraction and separating them from the illumination light beam. The transparent flat plate on which the diffraction grating is formed, the light receiving element substrate on which multiple light receiving elements for detecting the light beam split by the diffraction grating are formed, and the base that holds the light source unit and the light receiving element substrate. The light source unit, the light receiving element substrate, and the base are integrated, and the plurality of light receiving elements are located on substantially the same plane and near the laser light source. Is fixed to the light receiving element substrate, and the base is a substrate holding part to which the light receiving element substrate is attached,
It has a light source holding part to which the light source unit is attached, and the substrate holding part has ultraviolet transparency, and enables ultraviolet rays to pass through and irradiate the contact part with the light receiving element substrate. The light source holder has a through hole in which the light source unit can be slidably accommodated in the inner space, and the light source holder has ultraviolet transparency, which allows ultraviolet rays to pass through it. The light receiving element substrate is fixed to the substrate holding part with an ultraviolet curing adhesive, and the light source unit is a light source holding part with an ultraviolet curing adhesive. An optical pickup that is fixed to. 5. The substrate holder and the light source holder are mainly made of Al ₂
The optical pickup according to claim 4, wherein the optical pickup is made of any one of O ₃ , SiO ₂ , MgO, and Ta ₂ O ₃ or a mixture thereof. 6. The optical pickup according to claim 5, wherein the substrate holding part and the light source holding part have an ultraviolet transmittance of 1% or more and a visible light transmittance of 10% or less in a thickness of 1 mm. . 7. The light source unit has a holding member for holding the laser light source, and the holding member has a holding member main body slidably engaged with a through hole of the light source holding portion, and a holding member main body protruding from the holding member main body. The optical pickup according to claim 6, wherein the laser light source is attached to the convex portion. 8. A light source unit including a laser light source that emits an illumination light beam for illuminating a recording medium, and a reflected light beam reflected by the recording medium is divided into a plurality of light beams by diffraction to be separated from the illumination light beam. And a plurality of light receiving elements for detecting the light beam divided by the diffraction grating, a light source unit and a base holding the light receiving element, and at least a light source unit, a light receiving element, and a base. , The multiple light-receiving elements are located on almost the same plane and near the laser light source, and the base is UV-transparent. It is possible to irradiate the contact part with the element and the contact part with the light source unit, the light receiving element is fixed to the base by an ultraviolet curable adhesive, and the light source unit is UV cured. A method of manufacturing an optical pickup, which is fixed to a base with a chemical adhesive, in which the light source unit is held in contact with the base via an ultraviolet curable adhesive, and the light receiving element is cured with the ultraviolet curable adhesive. A method of manufacturing an optical pickup, including a step of contacting and holding a base through an agent and a step of irradiating the ultraviolet curable adhesive with ultraviolet rays through the base to cure the ultraviolet curable adhesive. . 9. A light source unit including a laser light source that emits an illumination light beam for illuminating a recording medium, and a reflected light beam reflected by the recording medium is divided into a plurality of light beams by diffraction to be separated from the illumination light beam. , A transparent flat plate on which the diffraction grating is formed, a light receiving element substrate on which a plurality of light receiving elements for detecting the light beam divided by the diffraction grating are formed, and a base for holding the light source unit and the light receiving element substrate. And a light source unit, a light-receiving element substrate, and a base are integrated, and the plurality of light-receiving elements are located on substantially the same plane and near the laser light source. Is fixed to the light-receiving element substrate, and the base has a substrate holding portion to which the light-receiving element substrate is attached and a light source holding portion to which the light source unit is attached. It is transparent to outside rays and allows ultraviolet rays to pass through and irradiate the contact area with the light receiving element substrate. The light source holder can slide the light source unit inside the space. Has a through hole that can be accommodated in, and the light source holding portion has ultraviolet transparency,
It allows ultraviolet rays to pass through and irradiate the contact part with the light source unit, the light receiving element substrate is fixed to the substrate holding part with the ultraviolet curing adhesive, and the light source unit is the ultraviolet curing adhesive. A method of manufacturing an optical pickup, which is fixed to a light source holding part with an agent, including a step of inserting the light source unit into a through hole of the light source holding part through an ultraviolet curable adhesive, and a step along an optical axis of the light source unit. Adjusting the position, irradiating the UV-curable adhesive with UV light through the light source holder to cure the UV-curable adhesive, and mounting the light-receiving element substrate on the substrate holder via the UV-curable adhesive. The optical pickup manufacturing process includes a step of placing and positioning and a step of irradiating the ultraviolet curable adhesive with ultraviolet rays through the substrate holding part to cure the ultraviolet curable adhesive. Method.