JP3520621B2 - Optical pickup and optical pickup for phase change optical disk - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element, an optical pickup for recording or reproducing information on an optical disc, and an optical pickup for a phase change type optical disc.

[0002]

2. Description of the Related Art Conventionally, there has been a demand for miniaturization of an optical disc device which records and reproduces information by using a laser beam, and attempts have been made to miniaturize and reduce the weight of an optical pickup by reducing the number of optical components. It is being appreciated. Compact optical pickup
The reduction in weight is advantageous not only for downsizing the entire apparatus but also for improving performance such as shortening access time. In recent years, the use of hologram optical pickups has been mentioned as a means for reducing the size and weight of optical pickups, and some of them have been put to practical use.

[0003]

However, in the conventional optical pickup, since the bonding material used for assembling the optical pickup is not strictly defined, the thickness of the bonding material after curing is too thin and the ringing occurs. Caused
There is a problem that it is difficult to align each member, conversely, the thickness of the bonding material is too thick and the bonding strength of the bonding part is not insufficient, and the bonding part between each member is dissociated. I had a problem.

The present invention solves the above-mentioned problems of the prior art. By controlling the thickness of the bonding material to be in the optimum range, the workability in the assembly process of the optical pickup is improved and the optical pickup is made. It is an object of the present invention to provide an optical pickup for greatly improving the reliability of the optical pickup and an optical pickup for a phase change type optical disc.

[0005]

In order to achieve this object, in an optical pickup in which members are joined together by a joining material, the thickness (t) of the joining material after curing is 1≤t≤30.
0 (μm), preferably 1 ≦ t ≦ 30 (μm), and more preferably 3 ≦ t ≦ 7 (μm).

[0006]

With this structure, it is possible to suppress the occurrence of ringing between the respective members and to ensure sufficient bonding strength.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The packaging of an optical pickup according to the first embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are sectional views showing the packaging structure of an optical pickup according to the first embodiment of the present invention.

Reference numeral 1 denotes a light source. As the light source 1, various lasers such as a semiconductor laser and a gas laser such as He-Ne can be considered. Here, it is preferable to use a semiconductor laser which is the smallest in size among them and can be downsized as a whole, and which has a low output of several mW to several tens of mW. The material of the semiconductor laser is AlGaAs, InGaAsP, I
nGaAlP, ZnSe, GaN, etc. are considered, and the most commonly used and cheap AlGaAs is used here. When performing high-density recording, the spot diameter on the recording medium can be made smaller.
It is preferable to use a semiconductor laser such as InGaAlP or ZnSe having a wavelength shorter than s.

Reference numeral 2 denotes a submount, and the submount 2 has a rectangular parallelepiped shape or a plate shape, and the light source 1 is attached to the upper surface thereof. This submount 2 is a light source 1
And has a function of releasing heat generated by the light source 1. Considering heat conduction and the like in joining the submount 2 and the light source 1, Au is previously formed on the upper surface of the submount 2.
-Sn or other solder is plated and soldered at high temperature, or Au-Sn, Sn-Pb, Sn-Pb-In or other foil (thickness of several μm to several tens of μm) is pressure-bonded at high temperature Is preferably used. Also, if the light source 1 and the submount 2 are not mounted substantially horizontally, they will cause aberrations in the optical system and decrease in coupling efficiency. Therefore, at the time of joining, it is preferable that the light source 1 is mounted on the submount 2 at a predetermined position and at a predetermined height substantially horizontally. Further, an electrode surface 2a is provided on the upper surface of the submount 2 so as to make electrical contact with the lower surface of the light source 1. The electrode surface 2a is for supplying power to the light source 1, and as the metal film forming the electrode surface 2a, it is preferable to use a thin film of Au in consideration of conductivity and corrosion resistance. Further, the submount 2 has a high thermal conductivity and a coefficient of linear expansion of that of the light source 1 (about 6.5 × 10 ⁻⁶ / ° C.) due to heat generated by the light source 1 and mounting problems with the light source 1. A material close to () is preferable. Specifically, the coefficient of linear expansion is 3 to 10 × 1.
A substance having a thermal conductivity of 100 W / mK or more at 0 ^-6 / ° C, such as AlN, SiC, T-cBN, Cu / W, C
It is preferable to use u / Mo, Si or the like, particularly diamond or the like when the thermal conductivity must be extremely high, especially when a high-power laser is used. When the linear expansion coefficients of the light source 1 and the submount 2 are set to be the same or close to each other, it is possible to suppress the occurrence of distortion between the light source 1 and the submount 2, so that It is possible to prevent inconveniences such as detachment of the mounting portion and cracking of the light source 1. However, if it is out of this range, a large distortion may occur between the light source 1 and the submount 2, and the mounting portion between the light source 1 and the submount 2 may come off, or the light source 1 may be cracked or the like. Get higher Further, by taking the thermal conductivity of the submount 2 as large as possible, the heat generated in the light source 1 can be efficiently released to the outside. However, when the thermal conductivity is less than or equal to this limit, the heat generated in the light source 1 becomes difficult to escape to the outside, so that the temperature of the light source 1 rises, the output of the light source 1 decreases, and the life of the light source 1 shortens. In some cases, inconveniences such as destruction of the light source 1 in the worst case may occur. In this example, AlN was used because it is relatively inexpensive and has excellent properties for both of these two characteristics. Furthermore, in order to improve the bondability with the light source 1 on the upper surface of the submount 2, Ti, Pt,
It is preferable to form a thin film in the order of Au.

Reference numeral 3 is a block, and the block 3 is basically rectangular parallelepiped and has a large protrusion 3a on its side surface, and the submount 2 is attached to the upper surface thereof. Similar to the submount 2, this block 3 also has a high thermal conductivity and a linear expansion coefficient close to that of the submount 2 due to problems such as heat generated in the light source 1 and attachment to the submount 2, for example, It is preferable to use Mo, Cu, Fe, Kovar, 42 alloy, or the like other than those shown in the material examples of the submount 2. However, since the requirements for these characteristic values are not so strict as compared with the submount 2, it is preferable to select them in consideration of cost. Here, the block 3 is formed of a material such as Cu or Mo which is much cheaper than AlN and is relatively excellent in these characteristics. In consideration of heat conduction and the like for joining the block 3 and the submount 2, as in the case of the submount 2 and the light source 1, the foil (thickness such as Au-Sn, Sn-Pb, Sn-Pb-In (thickness) is also used. It is preferable that the pressure of several μm to several tens of μm) is applied at high temperature.

A heat radiating plate 4 serves to radiate the heat generated by the light source 1 and transmitted through the submount 2 and the block 3 by conduction to the outside.
Various members forming an optical pickup are placed and serve as a packaging substrate. Further, the heat dissipation plate 4 is provided with a hole 4a for adjustment. The block 3 is previously brazed and fixed to the upper surface of the heat dissipation plate 4 by solder foil or the like.
As the material of the heat dissipation plate 4, Cu, Al, which has high thermal conductivity,
Fe or the like is considered.

The submount 2 and the block 3 are shown here.
Although they are formed separately, when the output of the light source 1 is high and high thermal conductivity is required for these members, these members are integrally formed to improve the thermal conductivity. It is preferable. In this case, it is preferable to use a material having a very high thermal conductivity such as AlN.

It is desirable that the block 3 is larger than the submount 2 so that the contact area with the heat sink 4 is large.

Since the light source 1 is required to have high accuracy with respect to the optical axis, the upper surface of the submount 2 is preferably horizontal with high accuracy. Therefore, it is preferable to pay close attention to the attachment of the submount 2, the block 3 and the heat sink 4.

Reference numeral 5 denotes a light guide member, which has a rectangular parallelepiped shape, has a plurality of slopes and various films formed on these slopes, and is emitted from a light source. It has a function of emitting the emitted light and guiding the returned light to a predetermined position. The side surface of the light guide member 5 is joined to the end surface portion 3b of the protrusion 3a of the block 3. As the bonding material used here, it is preferable to use a photo-curable adhesive that is cured by irradiation with light having a predetermined wavelength. Among them, it is particularly preferable to use light in the infrared region, the ultraviolet region, and the visible light region where light emission is particularly easy. Good workability can be easily obtained by using such a bonding material, and further shortening of the bonding time can be easily achieved by controlling the amount and energy of the irradiation light to be optimum. Become. A moisture-curing type instant adhesive may be used. Also in this case, good workability can be easily obtained.

The joint strength of the joint portion is proportional to the contact area and inversely proportional to the thickness of the joint layer. Therefore, by making the contact area as wide as possible or making the joint material layer as thin as possible, Since the bonding strength can be increased, the reliability of the optical pickup can be improved as a result, which is preferable. However, if the thickness of the bonding material layer is too thin, ringing occurs between the block 3 and the light guide member 5, and it becomes very difficult to perform alignment when bonding the two. Therefore, it is necessary to give the bonding material layer a certain thickness.

On the contrary, if the thickness of the layer of the bonding material is too thick, the bonding strength between the block 3 and the light guide member 5 decreases, and in the worst case, the light guide member 5 is dissociated from the block 3. There is a possibility that it will end up. Therefore, in this embodiment, it is preferable that the thickness (t ₁ ) of the bonding material layer after curing when the bonding area (S) is S ≧ 1 mm ² is 1 ≦ t ₁ ≦ 100 (μm). By controlling the thickness of the bonding material so as to be in such a range, it is possible to suppress the occurrence of ringing and to secure a sufficient bonding strength between the block 3 and the light guide member 5. Therefore, the workability in the assembly process of the optical pickup can be improved,
Moreover, the reliability of the optical pickup can be greatly enhanced.

In particular, the thickness (t ₁ ) of the bonding layer after curing is 1 ≦.
Even when t ₁ ≦ 100 (μm), when the bonding strength between the block 3 and the light guide member 5 is required (for example, when the optical pickup is mounted on a vehicle or is portable). Is the thickness of the bonding material after curing (t ₂ ).
Is preferably 1 ≦ t ₂ ≦ 10 (μm). By controlling the thickness of the bonding material within such a range, it is possible to further increase the bonding strength between the block 3 and the light guide member 5 while suppressing the occurrence of ringing. It is possible to provide an extremely reliable optical pickup in which the joint portion between the two does not dissociate even when vibration is applied.

Further, the thickness (t ₂ ) of the bonding layer after curing is 1 ≦.
Even if t ₂ ≦ 10 (μm), the light guide member 5
And very high accuracy is required for the alignment of the block 3 (that is, the alignment between the light guide member 5 and the light source 1),
In addition, when a strong bonding strength is required, the thickness (t ₃ ) of the bonding material after curing is preferably 3 ≦ t ₃ ≦ 7 (μm).

The thickness (t ₃ ) of the bonding material after curing is t ₃ <3.
In the case of (μm), it is not possible to completely suppress the occurrence of ringing, so that it becomes difficult to finely adjust the position with extremely high accuracy, and the yield is reduced. Also t ₃ ＞
In the case of 7, the volume of the cured bonding layer increases or decreases relatively easily if there is a relatively large temperature change after curing of the bonding material, that is, the expansion or contraction of the bonding layer causes the bonding layer to expand. Since the thickness also changes, the positional relationship between the two may be misaligned even after highly accurate positioning.

By controlling the thickness of the bonding material so that t ₃ is within the range of 3 ≦ t ₃ ≦ 7 (μm), the ringing can be almost eliminated and the block 3 and the optical guide can be eliminated. Since it is possible to minimize the amount of misalignment that is thought to occur due to the expansion of the bonding layer with the member 5 due to the temperature change, the workability in the assembly process of the optical pickup can be optimized. ,And,
The reliability of the optical pickup can be greatly enhanced.

Reference numeral 13 denotes a light receiving element, and the light receiving element 13 is composed of various electric circuits formed on a plate-shaped semiconductor wafer, and is attached to the bottom surface of the light guide member 5. At the time of attachment, the position is adjusted using the hole 4a provided in the heat dissipation plate 4. Regarding the attachment of the light receiving element 13 and the light guide member 5, there is great adhesive strength, workability that can be fixed at an arbitrary moment, change in volume before and after curing, temperature,
Conditions such as a low shrinkage ratio that requires a small volume change due to humidity are required. By satisfying these conditions, workability and the stability of the joint surface are improved. As such a bonding material, it is preferable to use a photo-curing type adhesive which is cured by irradiating with light having a predetermined wavelength. Among them, it is particularly preferable to use light in the infrared region, the ultraviolet region, and the visible light region where light emission is particularly easy. Good workability can be easily obtained by using such a bonding material, and further shortening of the bonding time can be easily achieved by controlling the amount and energy of the irradiation light to be optimum. Become. A moisture absorption hardening type instant adhesive may be used as another bonding material. Also in this case, good workability can be easily obtained.

The joint strength of the joint portion is proportional to the contact area and inversely proportional to the thickness of the joint layer. Therefore, by making the contact area as wide as possible or making the joint material layer as thin as possible, Increase the bonding strength,
As a result, the reliability of the optical pickup can be improved, which is preferable. However, if it is made too thin, ringing will occur between the light guide member 5 and the light receiving element 13, and it will be very difficult to perform alignment when joining the two. Therefore, it is necessary to give the bonding material layer a certain thickness. On the contrary, if the thickness of the layer of the bonding material is too thick, the bonding strength between the light guide member 5 and the light receiving element 13 will be reduced. Unlike the case, since the light-receiving element 13 to be bonded is extremely lightweight, the necessary bonding strength can be obtained without strict regulation of the thickness of the bonding material layer and the area of the bonding surface. Therefore, in this embodiment, the bonding area (S) is S ≧ 1 m.
When the thickness (t ₁ ) of the bonding material layer when m ² is 1 ≦ t
It is preferable that ₁ ≦ 300 (μm). By controlling the thickness of the bonding material to be in such a range,
Since the occurrence of ringing can be suppressed and the bonding strength between the light receiving element 13 and the light guide member 5 can be sufficiently secured, the workability in the assembly process of the optical pickup can be improved. In addition, the reliability of the optical pickup can be greatly improved.

In particular, the thickness (t ₁ ) of the bonding layer after curing is 1 ≦.
When the bonding strength between the block 3 and the light guide member 5 is required even in the range of t ₁ ≦ 300 (μm) (for example, when the optical pickup is mounted on a vehicle or carried around) Is the thickness of the bonding material after curing (t ₂ ).
Is preferably 1 ≦ t ₂ ≦ 30 (μm). By controlling the thickness of the bonding material so as to fall within such a range, it is possible to further increase the bonding strength between the light receiving element 13 and the light guide member 5 while suppressing the occurrence of ringing. It is possible to obtain an extremely reliable optical pickup in which the joint portion of the both does not dissociate even when the vibration of (1) is applied.

Further, the thickness (t ₂ ) of the bonding material after curing is 1 ≦.
Even if t ₂ ≦ 30 (μm), the light guide member 5
When very high accuracy is required for the alignment between the light receiving element 13 and the light receiving element 13 and a strong joining strength is required, the thickness (t ₃ ) of the joining material after curing is 3 ≦ t ₃ ≦ 7. (Μm) is preferable.

The thickness (t ₃ ) of the bonding material after curing is t ₃ <3.
In the case of (μm), it is not possible to completely suppress the occurrence of ringing, so that it becomes difficult to finely adjust the position with extremely high accuracy, and the yield is reduced. Also t ₃ ＞
In the case of 7, the volume of the cured bonding layer increases or decreases relatively easily if there is a relatively large temperature change after curing of the bonding material, that is, the expansion or contraction of the bonding layer causes the bonding layer to expand. Since the thickness also changes, the positional relationship between the two may be misaligned even after highly accurate positioning.

By controlling the thickness of the bonding material so that t3 is in the range of 3≤t3≤7, ringing can be almost eliminated and the light receiving element 13 and the light guide member 5 can be formed. Since it is possible to minimize the amount of misalignment that is thought to occur due to the expansion of the bonding layer between them due to temperature changes, the workability in the assembly process of the optical pickup can be optimized, and The reliability of the pickup can be greatly increased.

When the light guide member 5 and the block 3 are bonded and the light guide member 5 and the light receiving element 13 are bonded to each other by using a photo-curable adhesive as a bonding material, A photocurable adhesive used for joining the light guide member 5 and the light receiving element 13 with a wavelength of light required for curing the photocurable adhesive used for joining the guide member 5 and the block 3 together. It is preferably longer than the wavelength of light required to cure. In this way, in a state of also applying a bonding material to the bonding site of either advance, it is possible to perform the bonding of the respective joint portions by changing the wavelength of the irradiated light. Therefore, unlike the conventional case, it is not necessary to apply the bonding material to the next place every time the joining of one place is completed, which leads to the reduction of the manufacturing process and the manufacturing time, which is a very preferable configuration.

Further, the light receiving element 13 is emitted from the light source 1,
It has a plurality of light receiving portions for receiving the optical signals reflected and returned by the light guide member 5 and the recording medium. The optical signal detected by the light receiving unit is converted into an electric signal according to the amount of light. This electric signal has a magnitude of a current value at the beginning of conversion. However, this current has a demerit that it is extremely weak and noise is easily picked up. Therefore, it is preferable to use the light receiving element 13 in which an IV amplifier having a function of converting a current value into a correlated voltage value and amplifying it is formed. However, it is required that the output voltage has a good response to the incident frequency of light. Further, the surface of the light receiving element 13 is provided with a plurality of electrodes 13a made of a thin film of Al or the like for taking out the received information as a signal.

14 is a package, and the package 14 is
On the upper surface of the heat dissipation plate 4, the above-mentioned block 3 and the light guide member 5,
It is provided so as to surround the light receiving element 13 and the like, and inside thereof, a lead frame 14a used for taking out an electric signal from the light receiving element 13 and supplying power to the light source 1 is molded. The package 14 has a rectangular parallelepiped shape with a hollowed central portion.
The step 14 is formed on the inner surface of the package 14 on the side where 4a is molded so as to expose the foot 14b of the lead frame.
c is provided. The shape of the package 14 may be cylindrical or the like. The lead frame foot 14b exposed on the step 14c provided on the package 14 for taking out an electric signal from the light receiving element 13
And a plurality of electrodes 13 provided on the surface of the light receiving element 13.
A is connected to a by wire bonding with a wire 14d made of Au, Al, or the like. Further, in order to supply power to the light source 1, the upper surface of the light source 1 and the foot 14b of the lead frame exposed on the step 14c provided on the package 14 are bonded with a wire 14d, and the submount 2
The electrode surface 2a, which is provided on the upper surface of the above so as to make electrical contact with the lower surface of the light source 1, and the foot 14b of the lead frame exposed at the step 14c provided on the package 14 are wire-bonded by the wire 14d as well. By connecting. The material of the package 14 is required to be excellent in low water absorption, low outgassing, etc. Here, a thermosetting resin such as an epoxy resin, which is the most common as an IC mold, is used. As the material of the lead frame 14a, a metal such as Cu, 42 alloy or Fe plated with Ag or Au is often used. Here, Cu was plated with Ni, and then Au was plated thereon. Further, for attachment between the package 14 and the heat dissipation plate 4, a bonding material having properties such as high adhesive strength, low water absorption, high airtightness (low leak characteristic), etc. is used. As a result, the stability of the bonding surface and the bonding position can be improved, and impurities can be prevented from entering the inside of the packaging of the optical pickup. Here, an inexpensive epoxy adhesive excellent in these characteristics was used.

Reference numeral 15 denotes a shell, and the shell 15 also has an outer shape like a rectangular parallelepiped hollowed out like the package 14, and its horizontal cross section is substantially the same as that of the package 14. . In addition, the material is required to have characteristics such as low water absorption and low outgassing in order to prevent impurities from entering the inside of the packaging. Here, polybutylene terephthalate (hereinafter referred to as PBT) having excellent properties was used. However, especially when properties such as strength and dimensional accuracy are required, an LCP that is more expensive than PBT but is excellent in these properties may be used. And the adhesion between the shell 15 and the package 14 is
An epoxy adhesive was used for the same reason as the mounting of the package 14 and the heat dissipation plate 4 described above. This shell 1
Instead of using 5, the height of the side wall portion of the package 14 may be made higher than that of the light guide member 5 for substitution.

Reference numeral 16 is a cover member, and the cover member 16 prevents dust and the like from adhering to the light guide member 5, the light receiving element 13 and the like, and is attached to the upper surface of the shell 15 by an epoxy adhesive. ing. Further, as the material of the cover member 16, it is preferable to use a glass positioning disk portion 4c such as BK-7 or Kovar glass. Further, it is preferable to form an antireflection film 16a on the upper and lower surfaces of the cover member 16 to prevent reflection. This antireflection film 16a is preferably formed of a material such as MgF ₂ .

As for the positional relationship between the cover member 16 and the light guide member 5, it is considered that the cover member 16 and the light guide member 5 are in contact with each other and a space is provided between them. When the two are brought into contact with each other, the light guide member 5 is attached to the bottom of the cover member 16 with an epoxy adhesive, a UV adhesive, or the like. At this time, the thickness (t1) of the cover member 16 is 0.3 ≦ t1 ≦ 3.0 (m
m) is preferable. The reason for this is that if the lower limit is made thinner than this, the cover member 16 may not be able to withstand the weight of the attached light guide member 5 or the tension when the adhesive hardens, and may be damaged. Regarding the upper limit, since the cover member 16 has a larger refractive index than air, a converging action is generated on the light and the light does not spread. As a result, the cover member 16 and the collimator lens (in the case of an infinite optical system) or the objective lens This is because there is no choice but to increase the distance from (in the case of a finite optical system), which is disadvantageous for downsizing the pickup unit.
By using such a configuration, the height of the optical pickup can be further reduced, and the pickup unit can be downsized while maintaining sufficient mounting strength.

On the other hand, when a space is provided between the two, the thickness (t2) of the cover member 16 is set to 0.1≤t2≤.
It is preferable that the distance (d) between the cover member 16 and the light guide member 5 is 3.0 (mm) and 0.1 ≦ d ≦ 3.0 (mm). The reason for this is that the lower limit of t2 is different from the previous example in that the light guide member 5 is not attached, and it is only necessary to withstand external factors such as vibration. Regarding d, the smaller the better, the better it is, but the accuracy error during assembly may not be less than 0.1 mm. In this case, the cover member 16 comes into contact with the light guide member 5 during assembly and is damaged. There is a risk that By using such a configuration, the mounting relative positional accuracy between the light guide member 5, the light source 1, the submount 2 and the block 3 is improved, and the block 3 or the submount 2 is brought into thermal contact with another member. Therefore, the heat generated by the light source 1 can be easily released to the outside.

Inside the optical pickup, the light source 1 and the light receiving element 13 are prevented from being oxidized and the light guide member 5 and the cover member 1 are provided.
From the standpoint of preventing dew condensation at 6, etc., gas such as N ₂ or Ar, N
It is preferable to fill an inert gas such as e and He. In that case, the gap 17 existing between the heat sink 4 and the light receiving element 13 has a bonding material having characteristics such as a small shrinkage rate, low water absorption, and high airtightness (excellent leak characteristics), for example, an epoxy potting agent. It is necessary to fill it with solder or solder. Thereby, the airtightness inside can be improved.

By using the configuration shown above,
The heat generated by the light source 1 can be easily radiated to the outside, and by providing a total of two openings on both end faces of the packaging, the antioxidant gas can be easily enclosed. Further, in the optical system, since the relative positional relationship between the light source 1, the light guide member 5 and the light receiving element 13 can be correctly and firmly held, malfunctions due to the displacement of these positions, extra optical aberration, etc. occur. do not do.

The thermal resistance of the entire packaging of this optical pickup is preferably 35 ° C./W or less because heat can be more efficiently released to the outside of the package.

Next, the operation of the optical pickup according to the first embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a conceptual diagram of the operation of the optical pickup in one embodiment of the present invention, and FIG. 4 is a perspective view of the light guide member in the first embodiment of the present invention.

3 and 4, the laser light emitted horizontally from the light source 1 mounted horizontally on the heat sink 4 via the submount 2 and the block 3 has a plurality of parallel inclined surfaces. 5 is incident on the light guide member 5 from the surface 5f and is formed on the second slope 5b of the light guide member 5 and converts the diffusion angle of the emitted light with respect to the diffusion angle of the incident light (hereinafter NA is converted. Then, the reflection type diffusion angle conversion hologram 7 having a function is reached. The light whose NA is converted and reflected by the diffusion angle conversion hologram 7 is reflected by the reflection type diffraction grating 6 formed on the first slope 5a, and the 0th order diffracted light (hereinafter referred to as the main beam) and the ± 1st order diffracted light (hereinafter referred to as the side beam). Called)). The main beam and side beams generated by the diffraction grating 6 are incident on the first polarization-selective beam splitter film 9 (hereinafter simply referred to as the first beam splitter film). The first beam splitter film 9 is light having an oscillating component parallel to the incident surface (hereinafter simply referred to as P-polarized component).
, And has a constant reflectance for a vertical vibration component (hereinafter simply referred to as an S-polarized component). Of the light that enters the first beam splitter film 9, the light that passes through the first beam splitter film 9 is used as the monitor light of the light emitted from the light source 1. In addition, the main beam and the side beam linearly polarized to the S-polarized component reflected by the first beam splitter film 9 are:
The light passes through the surface 5e of the light guide member 5 and the cover member 16, enters the objective lens 26, and is focused on the recording medium surface 27a of the recording medium 27 by the condensing action of the objective lens 26. At this time, the beam spots 29a and 29c of the two side beams are imaged on the recording medium surface 27a at positions substantially symmetrical with respect to the beam spot 29b of the main beam. Beam spots 29b, 29a, and 29c of the main beam and side beams with respect to the recording medium surface 27a
By this, information recording or reproduction signals, tracking, and focusing, so-called servo signals are read out.

The diffusion angle conversion hologram 7 has a diffusion angle conversion hologram 7 with respect to a diffusion angle of a light beam of the light emitted from the light source 1 that can enter the diffusion angle conversion hologram 7.
Converts the diffusion angle of reflected light from. Also, the diffusion angle conversion hologram 7 can convert parallel light having no diffusion angle. Also, the same diffusion angle conversion hologram 7
Thus, as shown in FIG. 3, the light flux emitted from the light guide member 5 becomes an ideal spherical wave 30 from which the wavefront aberration accumulated in the midway path is removed. Therefore, the incident light on the objective lens 26 becomes an ideal spherical wave 30, and the beam spot on the recording medium 27 by the objective lens 26 is narrowed down to the diffraction limit to an ideal size, and information recording or reproduction is easily performed. You can

The return light of the main beam and the side beam reflected by the information recording surface 27a of the recording medium 27 passes through the objective lens 26 and the surface 5e of the light guide member 5 again,
The light enters the first beam splitter film 9 formed on the second inclined surface 5b of the light guide member.

Of the return light from the recording medium 27, the light transmitted from the first beam splitter film 9 is the light guide member 5.
Second polarization-selective beam splitter film 11 formed on a third slope 5c parallel to the first slope 5a of
(Hereinafter, simply referred to as a second beam splitter film). The second beam splitter film 11 is similar to the first beam splitter film 9 in that the P beam component is almost 10
It has a transmittance of 0% and has a constant reflectance for the S-polarized component.

Here, the transmitted light 117 of the light flux incident on the second beam splitter film 11 will be described. The transmitted light 117 enters the polarization plane conversion substrate 31 laminated on the third slope 5c.

FIG. 5 is a perspective view of a polarization plane conversion substrate according to one embodiment of the present invention, and FIG. 6 is a diagram showing the arrangement of light receiving portions and signal processing of an optical pickup according to one embodiment of the present invention.
The polarization plane conversion substrate 31 includes a first other slope 31a (hereinafter simply referred to as a first other slope) and a second other slope 31b (hereinafter simply referred to as a second other slope) substantially parallel to the first other slope 31a. ), The reflection film 126 is provided on the first other slope 31a,
The polarization separation film 12 is formed on each of the second other inclined surfaces 31b. The transmitted light 117 enters the polarization separation film 12 formed on the second other inclined surface 31b. The second other inclined surface 31b is formed so that the angle formed by the polarization plane 117a of the transmitted light 117 and the incident surface 128 is approximately 45 × (2n + 1) °: (n is an integer). As a result, the P-polarized component 117 of the transmitted light 117
The p and S polarization components 117s have an intensity ratio of approximately 1: 1. The P polarization component 117p having a polarization component parallel to the incident surface 128 is almost 100% due to the polarization separation film 12.
On the other hand, the S-polarized component 117s having a polarization component perpendicular to the incident surface 128 is reflected by the polarization separation film 12 on the second other inclined surface 31b by about 100% and is incident on the first other inclined surface 31a surface to form a reflection film. It is reflected by 126 and guided to the light receiving element 13. P polarization component 117p guided to the light receiving element 13
To the light receiving section 170, and similarly the S-polarized component 117s reaches the light receiving section 171 to create an RF signal.

Next, the reflected light 123 of the light beam incident on the second beam splitter film 11 shown in FIG. 3 will be described. The reflected light 123 enters the astigmatism generation hologram 10 formed by the reflection type hologram on the second slope 5b. The reflected light 123 generates astigmatism by the astigmatism generation hologram 10 and is further reflected by the reflecting films 124 and 125, and the return light of the main beam is transmitted to the light receiving section 172 on the light receiving element 13 to the side beam. The returning light of the above reaches the light receiving portions 176 and 177 on the light receiving element 13.

Next, in the first embodiment of the present invention, the structure of the optical pickup particularly adapted to the phase change type optical disk will be described with reference to the drawings. A phase-change optical disc records information by changing the crystal structure in the recording medium by irradiating light, and thus requires a larger amount of light than the conventional optical recording / reproducing device to change the crystal structure. Therefore, a more efficient optical system is required. FIG. 23 is a configuration diagram of an optical pickup for a phase change type optical disc in one embodiment of the present invention. The members having the same numbers as those shown in FIGS. 1, 2 and 3 have the same functions and configurations, and thus the description thereof will be omitted.

The laser light emitted from the light source 1 enters the light guide member 41 from the surface 41f of the light guide member 41 having a plurality of parallel inclined surfaces, and the diffusion angle conversion hologram 7, the diffraction grating 6 and the polarization selective light. A certain beam splitter film 3
After passing through 5 (hereinafter referred to as a beam splitter film), the light is emitted from the surface 41e of the light guide member 41. Here, unlike the case of the first embodiment, the beam splitter film 35 has an S-polarized component reflectance of 95% or more and a P-polarized component reflectance of about 1%. Of the light that enters the beam splitter film 35, the light that passes through the beam splitter film 35 (P
The polarized light component (about several percent of the total light amount) is used as the monitor light of the light emitted from the light source 1. Light guide member 4
The light emitted from the first surface 41 e passes through the λ / 4 plate 33 provided on the cover member 16. FIG. 24 is a schematic view of a λ / 4 plate in one embodiment of the present invention. The λ / 4 plate 33 has an extraordinary optical axis of π / 4 · (2m−1) with respect to the plane of polarization of the incident light from the light guide member 41 (where m is a natural number:
The same applies hereinafter) and has a function of generating a phase difference of π / 2 · (2m−1) between the extraordinary light component and the ordinary light component of the incident light. A uniaxial crystal material is generally used as a material forming the λ / 4 plate 33. Among them, it is preferable to use a crystal that is low in cost and excellent in light transmittance. The uniaxial crystal has an extraordinary optical axis 616 and an ordinary optical axis 617, and has different refractive indexes called extraordinary light refractive index n _e and ordinary light refractive index n _o with respect to each optical axis. Since the optical distances of the extraordinary light and the ordinary light are different, a phase difference Δ determined by the following relational expression occurs when the substrate thickness of the λ / 4 plate 33 is QD and the incident light wavelength is λ. The thickness QD of the λ / 4 plate 33 is determined so that the phase difference Δ is π / 2 · (2m−1).

Δ = 2π · (n _e −n _o ) · QD / λ In the present embodiment, the wavelength λ = 790 nm and the extraordinary light refractive index ne.
= 1.5477, and ordinary refractive index no = 1.5388 (however, the refractive index differs depending on the cutting angle of the substrate. Here, the refractive index is cut parallel to a plane including both the extraordinary optical axis and the ordinary optical axis). On the other hand, the substrate thickness of the λ / 4 plate 33 is 2
It becomes 1.9 · (2m−1) μm. By setting such conditions, it is possible to convert linearly polarized light having an incident angle of 0 degree into circularly polarized light. That is, the linearly polarized light including only the S-polarized component emitted from the light source 1 can be converted into circularly polarized light. In addition, here, a crystal of 21.9 μm was provided on the cover member 16 as the λ / 4 plate 33,
It may be provided on the surface 41e of the light guide member 41 or the objective lens 26.

The circularly polarized light transmitted through the λ / 4 plate 33 enters the objective lens 26 and is focused on the recording medium surface 27a of the recording medium 27 by the condensing action of the objective lens 26.
Is reflected. The rotation direction of the circularly polarized light reflected by the recording medium surface 27a is reversed, so that when the return light passes through the objective lens 26 and again through the λ / 4 plate 33, P
It is converted into linearly polarized light containing only the polarized component. The return light converted in this way again passes through the surface 41e of the light guide member 41 and again enters the beam splitter film 35 formed on the second inclined surface 41b of the light guide member 41. As described above, the beam splitter film 35 has a transmittance of about 100% for the P-polarized component and a reflectance of about 100% for the S-polarized component. Therefore, the return light having only the P-polarized component almost passes through the beam splitter film 35.

The return light then enters the half mirror 34 formed on the third slope 41c parallel to the first slope 41a of the light guide member 41. The half mirror 34 has a function of reflecting a predetermined amount of incident light and transmitting the rest.

Of the luminous flux that has entered the half mirror 34, the transmitted light 117 is guided to the light receiving portion 37 provided on the light receiving element 36.

Next, the reflected light 123 of the light beam incident on the half mirror 34 shown in FIG. 3 will be described. Figure 25
FIG. 4 is a layout view of a light receiving portion provided in a light receiving element of an optical pickup for a phase change type optical disc in an embodiment of the present invention. The reflected light 123 enters the astigmatism generation hologram 10 formed by the reflection type hologram on the second inclined surface 41b. The reflected light 123 generates astigmatism by the astigmatism generation hologram 10 and is further reflected by the reflecting films 124 and 125, and the return light of the main beam is transmitted to the light receiving portion 38 on the light receiving element 36 and the side beam. Of the return light reaches the light receiving portions 39 and 40 on the light receiving element 36.

In the optical pickup having the above-mentioned structure, the λ / 4 plate 33 is provided between the beam splitter film 35 and the recording medium 27, and the outgoing light, which is the linearly polarized light of the S-polarized component, is converted into circularly polarized light. The light reflected by the recording medium 27 is converted, and then the circularly polarized light, which is reflected by the recording medium 27 and whose rotation direction is reversed, is converted into linearly polarized light having only a P-polarized component and made incident on the beam splitter film 35. Of the S-polarized light component of the beam splitter film 35 can be significantly increased, and thus the amount of light with which the recording medium 27 is irradiated can be increased. . That is, the recording medium 27 can be efficiently irradiated with the limited output of the light source 1, and
The reflected light from the recording medium 27 can be efficiently guided to the light receiving element 37.

Next, a method of manufacturing the packaging of the optical pickup having the above-described structure will be described.

7 to 11 are views showing the manufacturing procedure of the packaging of the optical pickup in the first embodiment of the present invention. First, the light source 1, the submount 2 and the block 3 (hereinafter referred to as an LD block) are assembled. Before assembling, especially the end face portion 3b of the protrusion 3a of the block 3
Must be properly machined so that is perpendicular to the heat sink 4. The submount 2 and the block 3 are manufactured by punching out a pre-plated AlN plate or cutting it out using a dicing saw or the like. At that time, if surface roughness, flatness, and verticality are not sufficient, lapping may be performed. The light source 1 is attached to a predetermined position of the submount 2. Installation is Au-S in advance
A method of mounting the light source 1 at a high temperature on the upper surface of the submount 2 plated with solder such as n, Au-Sn, Sn-
This is carried out by a method such as using a foil of Pb, Sn-Pb-In or the like having a thickness of several [mu] m to several tens [mu] m and press-bonding it at a high temperature.
The submount 2 and the block 3 are attached by the method using the solder foil. However, when mounting the light source 1 and the submount 2 and the mounting of the submount 2 and the block 3 by different methods, it is necessary to mount them in order from the one having the highest operating temperature. It is preferable that a Ti or Pt film is formed on the bonding surface of these members, an Au film is further formed on the film, and bonding is performed there.
In particular, it is very preferable to use this method for mounting between the light source 1 and the submount 2 because it leads to improvement in reliability of the light source 1. Further, when assembling these members, in particular, the light source 1 is used so that the aberration of light does not become large.
It is necessary to pay attention so that the light emitting surface and the end surface portion 3b of the protrusion 3a of the block 3 are substantially parallel to each other and the distance error between both surfaces is 10 μm or less. By setting the error value in this way, it is possible to suppress the variation in the spread of the light incident on the diffusion angle conversion hologram 7, and thus the variation in the product characteristics.

Before the light source 1 and the submount 2 are attached to the block 3, the block 3 and the heat sink 4 are joined together by
It is brazed with g wax or the like. Therefore, it is preferable that the lower surface of the block 3 be plated with Ti—Pt—Au or Ti—Ni—Au on the heat dissipation plate 4 with Ni—Au.

As another assembly method, the assembled L
A method of mounting the D block (an assembly of the light source 1, the submount 2, and the block 3) at a predetermined position of the heat dissipation plate 4 in a predetermined state is also conceivable. In this case, a method such as soldering is used for attachment. At this time, it is necessary to take care so that the joining material used for assembling the LD block does not melt and the assembling accuracy does not deteriorate. It is possible to maintain the assembly accuracy only by preventing the melting, and it is possible to produce the optical pickup unit without malfunction. At this time as well, it is preferable that a Ti film is formed on the joint surface, a Ni or Pt film is formed thereon, and an Au film is further formed thereon, and then the joint is carried out there.

Next, the heat sink 4 with the LD block incorporated therein
Attach the package 14 in place on top. An epoxy adhesive is used for attachment. And light receiving element 1
3 is installed in the package 14, and each signal extraction electrode of the light receiving element 13 and the leg 14b of the corresponding lead frame are wire-bonded with the wire 14d. At this time, it is preferable to make the length of the wire used for wire bonding a little longer because the position of the light receiving element 13 is finely adjusted later. At the same time, the light source 1
For the power source, the electrode surface 2a of the submount 2 that is in contact with the bottom surface of the light source 1 through the upper surface and the Au surface of the light source 1 and the foot 14b of the lead frame are wire-bonded using the wire 14d. deep. At this time, the light receiving element 13 is only wire-bonded and is not fixed to the heat sink 4 or the light guide member 5.

Next, the light guide member 5 is attached to the end surface portion 3b of the block 3. Since this mounting requires extremely high precision, the method will be described in detail here with reference to the drawings. FIG. 12 is a conceptual diagram showing the inconsistency between the 0th order light and the 1st order light observed by the CCD in one embodiment of the present invention, and FIG. 13 is the 0th order light and the 1st order light observed by the CCD in one embodiment of the present invention. FIG. 14 is a conceptual diagram showing coincidence with light, and FIG. 14 is a conceptual diagram of an observation experiment in one embodiment of the present invention. First, the light guide member 5 held by air tweezers or the like is moved along the side surface of the block 3 to roughly align the position. At this time, the bonding agent is applied to at least one of the side surface portion of the light guide member 5 and the end surface portion 3b of the block 3. Here, as the bonding material, it is preferable to use a photo-curable adhesive that is cured by irradiation with light having a predetermined wavelength. Among them, it is particularly preferable to use light in the infrared region, the ultraviolet region, and the visible light region where the light source is generally easy to obtain. Good workability can be easily obtained by using such a bonding material, and further shortening of the bonding time can be easily achieved by controlling the amount and energy of the irradiation light to be optimum. Become. A moisture absorption hardening type instant adhesive may be used as another bonding material.

At this time, the bonding material has a bonding area (S) after the light guide member 5 and the block 3 are bonded and then cured.
Is S ≧ 1 mm ² , and the thickness (t ₁ ) of the bonding layer after curing is preferably 1 ≦ t ₁ ≦ 100 (μm), more preferably 1 ≦ t ₁ ≦ 100 (μm). Even if the thickness (t ₂ ) of the bonding layer is 1 ≦ t ₂ ≦ 10 (μm), the most preferable range is 1 ≦ t ₂ ≦ 10 (μm) even after the bonding layer is cured. It is preferable that the coating is performed so that the thickness (t ₃ ) is 3 ≦ t ₃ ≦ 7. By applying the bonding material in this way, ringing and the like are almost eliminated, and the alignment between the light guide member 5 and the block 3 is achieved by moving the light guide member 5 along the side surface of the block 3. This can be performed easily and surely, and sufficient bonding strength between the light guide member 5 and the block 3 can be ensured.

The film thickness is preferably controlled by the amount of adhesive applied, the viscosity, and the pressing force. Then, power is supplied to the light source 1 to cause it to emit light, and the light is introduced into the light guide member 5. The light introduced into the light guide member 5 is separated by the diffusion angle conversion hologram 7 into 0th-order diffracted light and 1st-order diffracted light, and thereafter emitted from the surface 5e of the light guide member 5 to the outside. The emitted light passes through a collimator lens (not shown) and the objective lens 26 to form an image at a position where the recording medium 27 should be. At this time, if the relative positions of the light source 1 and the light guide member 5 are correct, the 0th-order diffracted light and the 1st-order diffracted light converted by the diffusion angle conversion hologram 7 only have different depths of focus and focus at the same point. On the recording medium 27, it looks like concentric circles, as shown in FIG. If the relative position between the light source 1 and the light guide member 5 is not correct, the 0th-order diffracted light and the 1st-order diffracted light converted by the diffusion angle conversion hologram 7 have different depths of focus and focus points, and therefore the recording medium 2
On 7, the two circles are different as shown in FIG. Utilizing this fact, the charge-coupled device camera 3 is located at the recording medium position.
2 (hereinafter referred to as CCD) is set, the deviation between the 0th-order diffracted light and the 1st-order diffracted light is measured, the deviation width and the deviation direction are fed back, and the light guide member 5 is viewed by the CCD 32 according to the amount. The images of the two components are moved so that they form concentric circles. Thereby, the light source 1 of the light guide member 5
The position with respect to can be determined very accurately. After positioning the light guide member 5 in this manner, ultraviolet rays are irradiated to solidify the UV adhesive.

As a positioning method, a method of measuring the optical aberration of the first-order diffracted light by using a wavefront aberration measuring device or the like and positioning so that the aberration is minimized may be considered. However, when the three-beam method is used as the tracking signal detection method, the side beam also enters the wavefront aberration measuring device, and therefore three different lights are simultaneously measured, which makes it difficult to use this method. .

Next, the light receiving element 13 is attached to the light guide member 5 at a predetermined position. In this case also, since the light reflected by the recording medium 27 must be correctly guided to each light receiving portion of the light receiving element 13, precise relative alignment between the light receiving element 13 and the light guide member 5 is required. is there. Before describing this alignment method, the focus error signal detection by the astigmatism method in the light receiving element 13 and the state of astigmatism in this embodiment will be described with reference to the drawings.

FIGS. 15 to 17 show astigmatism light fluxes when the recording medium 27 is at the in-focus position, when the recording medium 27 is closer to the in-focus position, and when the recording medium 27 is far from the in-focus position. It is an external view. 18 to 20 show the astigmatism generation hologram 10 in the cases of FIGS. 15 to 17, respectively.
FIG. 3 is a diagram showing spot shapes of light generated by the light receiving elements 172a, 172b, 172c, and 172d provided on the light receiving element 13.

The astigmatism generation hologram 10 is used as the recording medium 2
7 is at the in-focus position, the first focus 178 is located upstream of the light receiving section 172 and the second focus 1 is located downstream of the light receiving section 172.
When 79 is generated and the X-axis direction and the Y-axis direction are taken as shown in FIGS. 18 to 20, a line image in the Y-axis direction is formed at the position of the first focus 178 and an X-axis is formed at the position of the second focus 179. Will connect the line image of. Further, when the recording medium 27 is at the in-focus position, the astigmatism generation hologram 10 is designed at a position where the spot diameters in the X-axis and Y-axis directions generated by astigmatism become equal and a circular spot shape is formed.

The focus error signal is received by the light receiving section 172a,
Photocurrent from 172b, 172c, 172d (or I-
The voltage converted by the V amplifier) is I172
a, I172b, I172c, and I172d are shown in FIG.
As can be seen from the circuit diagram of, it can be expressed by the following equation.

F. E. = (I172a + I172c)-
(I172b + I172d) When the recording medium 27 is at the in-focus position, the spot diameters in the X-axis and Y-axis directions become equal and a substantially circular spot shape is obtained, as can be seen from FIGS. 15 and 172a.
Since the total amount of light received at and 172c and the total amount of light received at 172b and 172d are equal, the focus error signal is given by the following equation.

F. E. = 0 When the recording medium 27 comes closer than the in-focus position, the first focus 178 and the second focus 179 generated in the astigmatism generation hologram 10 move away from the focus error detection element as shown in FIG. 172b, 172c, 172
The spot shape on d is an elliptical light flux having a major axis in the Y-axis direction, as shown in FIG. 19, and light receiving portions 172a and 172c.
The amount of light received by is larger than the amount of light received by the light receiving sections 172b and 172d, and the focus error signal is given by the following equation.

F. E> 0 When the recording medium 27 is separated from the in-focus position, the first focus 178 and the second focus 179 generated in the astigmatism generation hologram 10 are astigmatism generation hologram 10 as shown in FIG.
To approach the light receiving portions 172a, 172b, 172c, 1
The spot shape on 72d becomes an elliptical light flux having a long axis in the X-axis direction as shown in FIG.
The light receiving amount of 2d is larger than the light receiving amounts of the light receiving portions 172a and 172c, and the focus error signal is given by the following equation.

F. E <0 The focus error signal detection method as described above is known as the astigmatism method.

Therefore, in this embodiment, the light receiving element 13 is positioned using this principle. The light-receiving element 13 is held by using air tweezers that adsorb the back surface of the light-receiving element 13 from the hole 4a provided in the heat sink 4.
Is moved along the light guide member to enable fine adjustment of the installation position, and a reflection plate (not shown) is installed at the position of the recording medium 27. At this time, a predetermined bonding material is applied in advance to the bottom surface of the light guide member 5 or the top surface of the light receiving element 13. Here, as the bonding material, it is preferable to use a photo-curable adhesive that is cured by irradiation with light having a predetermined wavelength. Among them, it is particularly preferable to use light in the infrared region, the ultraviolet region, and the visible light region where the light source can be easily obtained. Good workability can be easily obtained by using such a bonding material, and further shortening of the bonding time can be easily achieved by controlling the amount and energy of the irradiation light to be optimum. Become. A moisture absorption hardening type instant adhesive may be used as another bonding material.

At this time, the bonding material has a bonding area (S) after curing after bonding the light guide member 5 and the light receiving element 13 to S ≧ 1 mm ² , and the thickness of the bonding layer after curing (t ₁ )
Is preferably 1 ≦ t ₁ ≦ 100 (μm),
More preferably, even if 1 ≦ t ₁ ≦ 100 (μm), the cured layer thickness (t ₂ ) is 1 ≦ t ₂ ≦ 10 (μm), and most preferably 1 ≦ t ₂ Even if it is in the range of ≦ 10 (μm), the thickness (t ₃ ) of the bonding layer after curing is 3 ≦ t ₃
It is preferable that the coating is performed so that ≦ 7. By applying the bonding material in this manner, the occurrence of ringing or the like is almost eliminated, and the position between the light guide member 5 and the light receiving element 13 is obtained by moving the light guide member 5 along the side surface portion of the light receiving element 13. The alignment can be performed easily and surely, and the bonding strength between the light guide member 5 and the light receiving element 13 can be sufficiently ensured.

The film thickness is preferably controlled by the amount of adhesive applied, the viscosity and the pressing force. Then, first, the intensity of the light reflected by the reflecting plate and returned is determined by the light receiving unit 17 of the light receiving element 13.
Monitor at 0, 171 etc. to determine the rough optimum position. Then, each of the light receiving portions 172a, 172b, 172c, 172 of the light receiving portion 172 which is divided into four parts next.
While monitoring the current or voltage (proportional to the amount of received light) from d, the reflector is intentionally oscillated parallel to the optical axis using a piezo element or the like. As a result, the reflection plate moves closer to or farther from the light receiving element 13. At this time, the light receiving portions 172a, 172b, 172c, 1
If the light receiving element 13 is moved so that the light amounts of 72d are substantially equal to each other, the light receiving element 13 can be precisely positioned with respect to the light guide member 5. The state of signals from the light receiving units 172a and 172b at this time is shown in FIGS.
Shown in 2. After positioning the light receiving element 13 in this manner, for example, when an ultraviolet curable adhesive (hereinafter referred to as a UV adhesive) is used as the bonding material, the UV adhesive is solidified by irradiating ultraviolet rays. After that, the gap 17 is closed with an epoxy potting agent or solder in order to seal the hole 4a for the air tweezers.

When a photo-curable adhesive is used for both the joint between the block 3 and the light guide member 5 and the joint between the light guide member 5 and the light receiving element 13, the light of the curing light is used. Between the light guide member 5 and the block 3, an adhesive having a different wavelength (that is, energy), for example, a UV adhesive that is cured between the light guide member 5 and the light receiving element 13 by irradiating with light having an energy of ultraviolet rays or less is used. A visible light adhesive which is cured by irradiating with light having an energy higher than visible light is applied in advance, and after positioning between the block 3 (that is, the light source 1) and the light guide member 5 is completed,
Visible light is radiated to cure the joint, and after positioning between the light guide member 5 and the light receiving element 13 is completed, ultraviolet rays are radiated to cause U between the light guide member 5 and the light receiving element 13.
It is preferred to cure the V adhesive.

[0076] Thus, in a state of also applying a bonding material to the bonding site of either advance, it is possible to perform the bonding of the respective joint portions by changing the wavelength of the irradiated light. Therefore, it is not necessary to apply the bonding material to the next place every time the joining of one place is completed unlike the conventional case, which leads to the reduction of the manufacturing process and the manufacturing time, which leads to the reduction of the cost, which is very preferable. It becomes a manufacturing method.

It should be noted that the recording medium 2 was actually used without installing a reflector.
7 may be arranged, the recording medium 27 may be rotated to generate surface wobbling, and the position may be adjusted accordingly. Further, here, the method of positioning the light source 1 and the light guide member 5 and the method of positioning between the light guide member 5 and the light receiving element 13 by causing the light source 1 to emit light has been described, but as another method, each component It is also conceivable to perform image recognition of the image using a CCD or the like, recognize positions of those parts and the reference, and position the parts so that the relative position dimension becomes a predetermined dimension.

Finally, in a separate step, a cover member 16 is previously attached to the upper surface of the shell 15 using an epoxy adhesive, and the bottom surface of this integrated member is attached to the package 14.
To the top of the. Epoxy adhesive is mainly used for attachment. Furthermore, this work is performed with N ₂ , He, Ne, Ar.
By performing in a dry antioxidant gas atmosphere such as
The inside of the packaging of the optical pickup can be purged.

By the manufacturing method as described above,
The packaging of the optical pickup is completed. By using such a manufacturing method, the packaging of the optical pickup having the light guide member 5 having such a shape can be performed more easily and precisely, and the yield can be improved.

By the manufacturing method as described above,
The packaging of the optical pickup is completed. By using such a manufacturing method, the packaging of the optical pickup having the light guide member 5 having such a shape can be performed more easily and precisely, and the yield can be improved.

[0081]

INDUSTRIAL APPLICABILITY According to the present invention, in an optical pickup in which members are joined with a joining material, the thickness (t) of the joining material after curing is 1 ≦ t ≦ 300 (μm), preferably 1 ≦ t ≦.
By setting 30 (μm), and more preferably 3 ≦ t ≦ 7 (μm), it is possible to suppress the occurrence of ringing between the respective members and sufficiently secure the bonding strength. The workability in the assembly process can be improved, and the reliability of the optical pickup can be greatly improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a packaging structure of an optical pickup according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a packaging structure of an optical pickup according to an embodiment of the present invention.

FIG. 3 is a conceptual diagram of the operation of the optical pickup according to the embodiment of the present invention.

FIG. 4 is a perspective view of a light guide member according to an embodiment of the present invention.

FIG. 5 is a perspective view of a polarization plane conversion substrate of an optical pickup according to an embodiment of the present invention.

FIG. 6 is a diagram showing a light receiving unit arrangement and signal processing of an optical pickup according to an embodiment of the present invention.

FIG. 7 is a diagram showing a manufacturing procedure of packaging of an optical pickup according to an embodiment of the present invention.

FIG. 8 is a diagram showing a manufacturing procedure of packaging of an optical pickup according to an embodiment of the present invention.

FIG. 9 is a diagram showing a manufacturing procedure of packaging of an optical pickup according to an embodiment of the present invention.

FIG. 10 is a diagram showing a manufacturing procedure of packaging of an optical pickup according to an embodiment of the present invention.

FIG. 11 is a diagram showing a manufacturing procedure of packaging of the optical pickup according to the embodiment of the present invention.

FIG. 12 is a conceptual diagram showing inconsistency between 0th-order light and 1st-order light observed by a CCD in one embodiment of the present invention.

FIG. 13 is a conceptual diagram showing coincidence between 0th-order light and 1st-order light observed by a CCD according to an embodiment of the present invention.

FIG. 14 is a conceptual diagram of an observation experiment in one example of the present invention.

FIG. 15 is an external view of an astigmatic light beam according to an embodiment of the present invention.

FIG. 16 is an external view of an astigmatic light beam according to an embodiment of the present invention.

FIG. 17 is an external view of an astigmatic light beam according to an embodiment of the present invention.

FIG. 18 is a diagram showing a spot shape of a beam on a light receiving portion in an embodiment of the present invention.

FIG. 19 is a diagram showing a spot shape of a beam on a light receiving portion in an embodiment of the present invention.

FIG. 20 is a diagram showing a beam spot shape on a light receiving portion in an embodiment of the present invention.

FIG. 21 is a diagram showing a sensor light amount on a light receiving portion in an embodiment of the present invention.

FIG. 22 is a diagram showing a sensor light amount on a light receiving portion in an embodiment of the present invention.

FIG. 23 is a configuration diagram of an optical pickup for a phase-change optical disk according to an embodiment of the present invention.

FIG. 24 is a schematic view of a λ / 4 plate according to an embodiment of the present invention.

FIG. 25 is a layout view of a light receiving portion provided in a light receiving element of an optical pickup for a phase change optical disc according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 light source 2 submount 2a electrode surface 3 block 3a protrusion 3b end surface 4 heat sink 4a hole 5 light guide member 5a first slope 5b second slope 5c third slope 5e surface 5f surface 6 diffraction grating 7 diffusion angle Conversion hologram 9 First beam splitter film 10 Astigmatism generation hologram 11 Second beam splitter film 12 Polarization separation film 13 Light receiving element 13a Electrode 14 Package 14a Lead frame 14b Lead frame foot 14c Step 14d Wire 15 Shell 16 Cover member 16a Antireflection film 17 Gap 26 Objective lens 27 Recording medium 27a Recording medium surface 29a, 29b, 29c Beam spot 30 Ideal spherical wave 31 Polarization plane conversion substrate 31a First other slope 31b Second other slope 32 CCD 33 λ / 4 plate 34 Half mirror 35 Beam splitter film 36 Light receiving element 37, 38, 39, 40 Light receiving part 41 Light guide member 41a First slope 41b Second slope 41c Third slope 41e Surface 41f Surface 117 Transmitted light 117a Polarization surface 117s S polarization component 117p P polarization component 123 Reflected light 124 Reflective film 125 Reflective film 126 Reflective film 128 Incident surface 170, 171, 172, 172a, 172b, 172
c, 172d, 176, 177 Light receiving part 616 Extraordinary optical axis 617 Ordinary optical axis

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-203420 (JP, A) JP-A-6-340849 (JP, A) JP-A-6-302044 (JP, A) JP-A-6- 80825 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 7/135 G02B 5/00 G11B 7/12

Claims (7)

(57) [Claims] 1. A light source and a holding member for holding the light source,
And a light receiving means for converting the light guide member having a plurality of inclined surfaces inclined relative to the direction of light emitted from the light source, a light signal received with receiving the light into an electrical signal, the holding The member is constructed separately from the light receiving means.
It is, by using the applied bonding material to at least one of the light guide member and the holding member, an optical pickup for bonding the light guide member and the holding member directly, after curing of the bonding material Thickness (t) of 1 ≦ t ≦ 10
An optical pickup characterized by being set to 0 (μm). 2. A light source, an optical guide member having a plurality of inclined surfaces inclined with respect to the incident direction of the light emitted from the light source, the light receiving member, and converting the received optical signal into an electric signal. A light receiving means, and using the first bonding material applied to at least one of the light source and the light guide member, bonds the light source and the light guide member in a predetermined positional relationship and receives the light. An optical pickup for joining the light receiving means and the light guide member by using a second joining material applied to at least one of the means and the light guide member, wherein the first joining material is cured. The subsequent thickness (t ₁ ) is 1 ≦ t ₁ ≦ 100 (μm), and the cured thickness (t ₂ ) of the second bonding material is 1 ≦ t ₂ ≦ 300.
(Μm), and when a photo-curing adhesive is used as the bonding material, the second bonding material is cured by irradiation with light having a longer wavelength than that of the first bonding material. Optical pickup to do. 3. A light source, a light guide member having a plurality of inclined surfaces that are inclined with respect to the incident direction of the light emitted from the light source, the light receiving member, and converting the received optical signal into an electrical signal. A light receiving means, and using the first bonding material applied to at least one of the light source and the light guide member, the light source and the light guide member are directly bonded and the light receiving means and the light are used. Using the second bonding material applied to at least one of the guide members,
An optical pickup for joining the light receiving means and the light guide member, wherein a thickness (t) of the first joining material after curing is set.
₁ ) is set to 1 ≦ t ₁ ≦ 100 (μm), the thickness (t ₂ ) of the second bonding material after curing is set to 1 ≦ t ₂ ≦ 300 (μm), and a photo-curing adhesive is used as the bonding material. When the agent is used, the second bonding material is cured by irradiation with light having a longer wavelength than that of the first bonding material, which is an optical pickup. 4. A light source and a holding member for holding the light source,
And a light guide member having a plurality of inclined surfaces that are inclined with respect to the incident direction of the light emitted from the light source; and a light receiving unit that receives the light and converts the received optical signal into an electrical signal. A first bonding material applied to at least one of the light guide member and the member, and a second bonding material applied to at least one of the light receiving means and the light guide member. An optical pickup for joining the light receiving means and the light guide member, wherein the thickness (t ₁ ) of the first joining material after curing is 1 ≦ t ₁ ≦ 100 (μm), The thickness (t ₂ ) of the second bonding material after curing is 1 ≦ t ₂ ≦ 300 (μm)
In the case of using a photo-curable adhesive as the bonding material, the second bonding material is cured by irradiating with light having a longer wavelength than that of the first bonding material. . 5. The optical pickup according to claim 1, wherein a photocurable adhesive is used as the bonding material. 6. The optical pickup according to claim 1, wherein a moisture absorption curing type adhesive is used as the bonding material. 7. An optical pickup for a phase change type optical disk corresponding to the phase change type optical disk, wherein the optical pickup according to any one of claims 1 to 6 is used. Optical pickup.