JP3536496B2 - Optical pickup - 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 pickup for recording or reproducing information on an optical element, an optical disc, etc., an optical pickup for a phase change type optical disc, and a manufacturing method thereof.

[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.

The structure of a conventional optical pickup will be described below with reference to the drawings. FIG. 11 is a sectional view of a conventional optical pickup. In FIG. 11, reference numeral 501 denotes a light source that emits light for irradiating a medium to read and write signals, and the light source 501 is mounted on the ceramic package 518 via the submount 502 and the block 3.
The heat generated by the light source 1 is conducted through the submount 502 and the block 503 and is radiated to the outside from the ceramic package 518. A light guide member 505 is provided on a side surface of the block 503, and a light receiving element 513 is provided on a bottom portion of the light guide member 505. Further, the cap 22 is attached to the upper end surface 518a of the ceramic package 518 via a ring 523. And cap 5
A cover member 516 that seals the opening 522 a provided in 22 is attached to the cap 522.

The light emitted from the light source 501 enters the light guide member 505. The light guide member 505 is the block 5
It is attached to the side surface of No. 03, the inside is provided with a plurality of slopes, and the slope is provided with a plurality of optical elements. The light incident from the light source 501 is guided by the light guide member 50.
The light is emitted toward the recording medium via the optical element provided at 5. Then, the light reflected by the recording medium and returned is split into a plurality of light beams through a plurality of optical elements provided in the light guide member 505, and is divided into a light receiving element 513 provided at the bottom of the light guide member. Be guided. Then, a predetermined signal is formed from the light guided by the light receiving element 513.

[0005]

However, in the conventional optical pickup, the ceramic package 51 is used.
No. 8 was used, the bondability with the cap 522 was not good, so it was necessary to insert the ring 523 having good bondability with both the ceramic package 518 and the cap 522. The manufacturing process is
A complicated process of joining the ring 523 on the ceramic package 518, and then aligning the cap 522 on the ring 523, and then joining must be performed, which increases the number of parts and the number of manufacturing steps. There was a problem that it would lead to an increase in cost.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides an optical pickup which is easy to manufacture and can reduce the number of parts, an optical pickup for a phase change type optical disk, and a manufacturing method thereof. Has an aim.

[0007]

In order to achieve this object, the lid member and the base forming the storage member are made of a metal material. Furthermore, it has the structure of joining them by a predetermined method.

[0008]

According to a first aspect of the present invention, there is provided a light source and a plurality of inclined surfaces which are inclined with respect to an incident direction of light emitted from the light source. A light guide member that guides light from the medium to a predetermined position via the plurality of slopes while guiding the light to the medium via the slope.
The light receiving means for receiving light and converting the received light signal into an electric signal, and the light source, the light guide member, and the light receiving means are contained, and a housing member made of a metal material is provided. In the pickup,
The resistance to external noise such as electromagnetic waves can be extremely increased.

According to the second aspect of the invention, the housing member is provided with the terminal connected to at least one of the light source and the light receiving means, so that the electric power is supplied to the light source while the inside of the optical pickup is sealed. It becomes possible to take out a signal from the light receiving means.

According to the structure of claim 3, the storage member is
Since it is made of a material containing at least one of e, FeNi alloy, and FeNiCo alloy, it is possible to particularly improve the blocking property against external noise.

According to the structure of claim 4, the light source, the light 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 the received light signal. To an electric signal, and a storage member that stores the light source, the light guide member, and the light receiving unit. The storage member includes at least a base and a lid member, and the base. Since both the lid member and the lid member are made of a metal material, the optical pickup can have extremely high resistance to external noise such as electromagnetic waves and can be easily placed inside the member such as the light source. It can be carried out and can be easily assembled.

According to the sixth aspect of the invention, since the projection is provided on at least one of the base and the lid member, the bondability between the base and the lid member can be improved, and the current value to be flown at the time of joining can be improved. Can also be smaller.

According to the structure of claim 7, the base is made of Fe, F.
Since it is made of a material containing at least one of an eNi alloy and a FeNiCo alloy, heat generated by the light source can be efficiently radiated to the outside.

According to the structure of claim 8, since the cap is made of a material containing at least one of FeNiCo alloy and FeNi alloy, the bondability with the base can be improved, and the high frequency superposition circuit can be realized. It is possible to efficiently block noise such as electromagnetic waves from the above.

According to the structure of claim 9, at least the light source, the light guide member and the light receiving means are housed between the base and the lid member, and at least one of N ₂ gas, inert gas and dry air is contained. With a predetermined current being applied between the base and the lid member in a state where the base is filled, a predetermined current is applied to weld the base and the lid member, so that the base and the lid can be more easily The members can be joined and the number of parts can be reduced.

The packaging of the 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 the 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 × 10 ^-6
/ C, a substance having a thermal conductivity of 100 W / mK or more, for example, AlN, SiC, T-cBN, Cu / W, Cu / M
It is preferable to use o, Si, etc., especially diamond, etc., when the thermal conductivity must be extremely high 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 the present embodiment, AlN, which is very excellent in both of these two characteristics, was used. Further, in order to improve the bondability with the light source 1, it is preferable to form a thin film in the order of Ti, Pt, and Au from the submount 2 toward the light source 1 on the upper surface of the submount 2.

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, FeNiCo alloy, FeNi 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 with the case of the submount 2 and the light source 1, Au-Sn, Sn-Pb, Sn-Pb-I are also used.
It is preferable to press-bond a foil such as n (thickness several μm to several tens μm) at high temperature.

The submount 2 and the block 3 are used 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.

Further, it is desirable that the block 3 is larger than the submount 2 to have a large contact area with the substrate 4.

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 attach the submount 2, the block 3 and the substrate 4 in the same manner.

The substrate 4 has a function of radiating the heat generated by the light source 1 and transmitted through the submount 2 and the block 3 by conduction or the like to the outside, and various members forming an optical pickup are mounted on the substrate 4. And is the basis of packaging. As the material of the substrate 4, it is preferable to use a metal material having high thermal conductivity such as Cu, Al, or Fe, or an alloy material such as FeNi alloy or FeNiCo alloy. This is because welding, which will be described later, is easy to perform and also has an effect as an electromagnetic shield that shields noise such as electromagnetic waves from the high frequency superposition circuit. Among these, especially Fe, FeNi alloys, FeNi
Since the Co alloy has low thermal resistance, good heat dissipation, and low cost, the heat generated in the light source 1 can be efficiently radiated to the outside, and the characteristics of the light from the light source 1 are excellent. It becomes possible to provide a good optical pickup at a low price.

The board 4 is provided with a hole 4a, which is used for inserting a jig for adjusting the position of each member. This makes it possible to easily align the positions of the respective members inside the optical pickup that require delicate alignment.

The members mounted on the substrate 4 will be described below. First, attachment of the block 3 and the substrate 4 will be described. The block 3 is fixed to the upper surface of the substrate 4 by a method such as brazing or solder foil with the submount 2 and the light source 1 fixed in advance.

Further, the substrate 4 is provided with terminals 14. The terminal 14 supplies power to the light source 1 and outputs a detected signal to the outside. Then, the plurality of holes 4b provided in the substrate 4 while being prevented from making electrical contact with the substrate 4 made of the metal material described above.
Has been inserted into. The material of this terminal 14 is FeN
It is preferable to use iCo alloy, FeNi, FeCr or the like. As a means for cutting off the electrical contact, it is preferable that an insulating film or the like is provided on a portion of the hole 4b which is in contact with the terminal 14 and the substrate 4, and the portion is hermetically sealed so that outside air does not enter from this portion. You need to do it. As such a member, it is preferable to use a hermetic seal or the like that can simultaneously perform both insulation and sealing. Here, it is particularly preferable to use a matching sealing type or a compression sealing type hermetic seal. This is because both insulation and sealing can be performed very easily, and the cost is extremely low, so that the process of attaching the terminal 14 to the substrate 4 can be simplified and the manufacturing cost of the optical pickup can be reduced. .

FIG. 10 shows a hermetic seal of matching sealing type.
As shown in FIG. 2, an outer ring metal 20 composed of FeNiCo alloy or the like is filled with an insulator 21, and the terminal 1 is provided at the center thereof.
It has a structure in which the lead 22 which becomes 4 is provided.
In particular, in consideration of the temperature rise due to heat from the light source 1, the lead 22 is made of a FeNiCo alloy having substantially the same expansion coefficient as glass as the insulator 21 up to about 500 ° C.
It is preferable to use it as the material.

By using this matching sealing type hermetic seal as the terminal 14, high airtightness and insulation can be maintained over a wide temperature range, and the terminal shape can be deformed relatively freely. The reliability of the optical pickup can be increased and the degree of freedom in design can be increased.

The light guide member 5 has a rectangular parallelepiped shape,
It has a plurality of slopes and various films formed on these slopes inside, and has the function of emitting the light emitted from the light source and guiding the returned light to a predetermined position. There is. Further, the light guide member 5 has a block 3 on its side surface.
Is joined to the end face portion 3b of the protruding portion 3a. 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 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 by using a position adjusting means such as an air brush inserted through the hole 4a provided in the substrate 4. Light receiving element 13
When the optical guide member 5 and the optical guide member 5 are attached to each other, large adhesive strength, workability that can be fixed at any moment, change in volume before and after curing, and change in volume due to temperature / humidity are small, that is, low shrinkage ratio, etc. Are required, and by satisfying these requirements, workability and stability of the joint surface are improved. Further, the light receiving element 13 has a plurality of light receiving portions that receive the optical signal emitted from the light source 1, reflected by the light guide member 5, the recording medium, or the like and returned. 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. Further, it is preferable that the response of the output voltage to the incident frequency of light is good. Further, a plurality of electrodes 13a made of a thin film of Al or the like for extracting the received information as a signal are provided on the surface of the light receiving element 13, and are connected to the terminals 14 by a method such as wire bonding.

Reference numeral 15 denotes a cap, which is joined to the substrate 4 so as to cover the light source 1, the light guide member 5, the light receiving element 13, etc., and the light source 1, the light guide member 5, the light receiving element 13, etc. are directly exposed to the outside air. It has a function of preventing the light from coming into contact with water and moisture, and also preventing the light mixed from the outside from entering the inside of the light guide member 5 and becoming noise.
In many cases, the cap 15 has a dome shape or a top hat shape, and a hole 15a is provided in a portion through which light passes, so that the passing light is not adversely affected. It is composed. And cap 1
The material of 5 is preferably a predetermined metal material or the like, which can be easily bonded to the substrate 4 and has a stable shape. Especially when the cap 15 is made of metal, the light source 1
It is possible to suppress unnecessary radiation from a power supply circuit that supplies electric power to the power supply and noise from other high frequency superposition circuits. Therefore, since noises resulting from these are not superimposed on various electric signals output from the optical pickup, it is possible to provide a high-performance optical pickup having a low noise level. Further, among the metal materials used for the cap 15, FeNiCo alloy, FeNi alloy and the like are preferable because they facilitate the formation of the cap 15, have a high ability to suppress unnecessary radiation, and have good bondability with the substrate 4. It is a material.

Reference numeral 16 is a cover member, which prevents dust and dirt from adhering to the light guide member 5, the light receiving element 13 and the like, and improves the light transmission efficiency. It is attached to the hole 15a with an adhesive glass or an epoxy-based bonding material. In particular, the adhesive glass is FeNiCo used as a material for the cap 15.
It is a preferable material because it has almost the same thermal expansion coefficient over a wide temperature range as the alloy, the FeNi alloy, and the glass as the material of the cover member 16. In addition, the cover member 16
The material, and crystalline glass PbO · B ₂ O ₃ · ZnO system, BK-7, it is preferably used an optical glass such as 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. By forming the antireflection film 16a, reflection and refraction of light in the cover member 16 can be suppressed, so that the light utilization efficiency can be improved. It is preferable that the antireflection film 16a is made of a material such as MgF ₂ because the antireflection can be efficiently performed.

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 1 existing between the substrate 4 and the light receiving element 13
7 needs to be filled with 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 or solder. Thereby, the airtightness inside can be improved.

By using the configuration shown above,
Since the thermal resistance of the substrate 4 and the cap 15 can be made smaller than in the conventional case, the heat generated in the light source 1 can be easily emitted to the outside as compared with the conventional case. Further cap 1
Since the clearance required for joining with the substrate 4 in 5 is very small, the substrate 4 and the cap 15 can be miniaturized, and therefore a compact optical pickup that meets the needs of the market can be provided. Further, since the substrate 4 and the cap 15 are made of a metal material, the entire package is at the ground level except for the cover member 16, so that it has a strong shielding effect against electromagnetic waves from the high frequency superposition circuit or the like. Therefore, the optical pickup is highly reliable and has a large resistance to noise such as electromagnetic waves.

By mounting the substrate 4 and the cap 15 in an atmosphere filled with at least one of N ₂ gas, inert gas and dry air, it is possible to easily apply a predetermined gas inside the package at a predetermined pressure. Can be enclosed,
As a result, it is possible to prevent the light source 1 and the light receiving element 13 from being deteriorated and to prevent the optical characteristics from being greatly deteriorated due to the dew condensation on the light guide member 5 and the like.

Next, a method of attaching the substrate 4 and the cap 15 in the optical pickup of this embodiment will be described.
The substrate 4 and the cap 15 have at least the light source 1,
The block 3, the light guide member 5, and the terminal 14 are attached so as to be included therein. The mounting is performed in an atmosphere filled with N ₂ gas, an inert gas, or dry air at a predetermined pressure because the predetermined gas can be easily sealed at a predetermined pressure inside the package. preferable. Then, the substrate 4 and the cap 15 are arranged in a predetermined positional relationship, set in a resistance welding machine, and the clearance portion 15b between the substrate 4 and the cap 15 is sandwiched by the electrodes of the welding machine to apply a predetermined current to the substrate 4 and the cap 15. The substrate 4 and the cap 15 are welded to each other by flowing the clearance portion 15b of the substrate 15. At this time, when the substrate 4 and the cap 15 are welded, it is preferable to apply a pressure of about several hundred g / cm ² to several kg / cm ² because the bondability between the substrate 4 and the cap 15 is improved. A condenser resistance welding machine was used as the welding equipment.

Further, in order to improve the weldability of both, it is preferable to provide a projection (projection portion having a triangular cross section) on at least one of the substrate 4 and the cap 15. As a result, the electric current concentrates on the top portion of the projection, so that portion can be easily melted. Therefore, the weldability between the substrate 4 and the cap 15 can be improved, and the value of the electric current flowing during welding can be reduced, and the welding time can be shortened, so that the manufacturing cost can be reduced. become.

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

In FIG. 3 and FIG. 4, the laser light emitted horizontally from the light source 1 mounted horizontally on the substrate 4 via the submount 2 and the block 3 has a plurality of parallel inclined surfaces. From the surface 5f of the light guide member 5
Of the reflection type having a function of converting the diffusion angle of the light which is incident on the second inclined surface 5b of the light guide member 5 and which is converted to the diffusion angle of the incident light (hereinafter referred to as NA conversion). Reach the diffusion angle conversion hologram 7. 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 has a transmittance of almost 100% with respect to light having an oscillating component parallel to the incident surface (hereinafter simply referred to as P-polarized component), and has a vertical oscillating component (hereinafter simply referred to as S (Referred to as the polarization component) has a constant reflectance. Of the light incident on the first beam splitter film 9, the light passing through the first beam splitter film 9 is the light source 1
It is used as the monitor light for the light emitted from. The main beam and the side beam linearly polarized to the S-polarized component reflected by the first beam splitter film 9 pass through the surface 5e of the light guide member 5 and the cover member 16 and enter the objective lens 26, and the objective lens An image is formed on the recording medium surface 27 a of the recording medium 27 by the condensing action of 26. At this time,
On the recording medium surface 27a, the beam spots 29a and 29c of the two side beams are imaged at positions substantially symmetrical with respect to the beam spot 29b of the main beam. Information recording or reproduction signals, tracking, and focusing, so-called servo signals are read from the recording medium surface 27a by beam spots 29b, 29a, and 29c of main beams and side beams.

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 a light receiving portion arrangement and signal processing of an optical pickup according to one embodiment of the present invention. The polarization plane conversion substrate 31 is the first other inclined surface 31.
a (hereinafter simply referred to as the first other slope) and the first other slope 31
The second other inclined surface 31b substantially parallel to a (hereinafter simply referred to as the second
(Referred to as another slope), and the reflection film 1 is provided on the first other slope 31a.
26, the polarization separation film 12 is formed on the second other inclined surface 31b. The transmitted light 117 enters the polarization separation film 12 formed on the second other inclined surface 31b. Second other slope 31b
Is formed such 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 117p and the S-polarized component 117s of the transmitted light 117 have an intensity ratio of about 1: 1. The P polarization component 117p having a polarization component parallel to the incidence plane 128 is transmitted by the polarization separation film 12 by almost 100%, while the S polarization component 117s having a polarization component perpendicular to the incidence plane 128 is on the second other slope 31b. Approximately 100% is reflected by the polarization separation film 12 and the first other slope 31
The light enters the a-plane, is reflected by the reflection film 126, and is guided to the light receiving element 13. The P-polarized component 117p guided to the light-receiving element 13 is sent to the light-receiving unit 170, and the S-polarized component 117s
Reaches the light receiving unit 171, and creates 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. Figure 7
FIG. 1 is a configuration diagram of a phase-change type optical disc compatible optical pickup according to an 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, the beam splitter film 35 is different from the case of the first embodiment in S
The reflectance of the polarized light component is 95% or more, and the reflectance of the P polarized light component is about 1%. Of the light that enters the beam splitter film 35, the light that passes through the beam splitter film 35 (a few percent of the total amount of light in the P-polarized component) is used as the monitor light of the light emitted from the light source 1. The light emitted from the surface 41 e of the light guide member 41 passes through the λ / 4 plate 33 provided on the cover member 16. FIG. 8 is a schematic view of a λ / 4 plate according to the embodiment of the present invention. The λ / 4 plate 33 is provided with respect to the plane of polarization of the incident light from the light guide member 41.
The extraordinary optical axis is installed in the direction of π / 4 · (2m−1); (where m is a natural number: the same below), and the phase difference between the extraordinary light component and the ordinary light component of the incident light is π / 2 · ( 2m-1) only. 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. In uniaxial crystal, extraordinary optical axis 616 and ordinary optical axis 61
7 and has different refractive indices called extraordinary index n _e and ordinary index n _o for each optical axis. Since the optical distances of extraordinary light and ordinary light are different, λ / 4
When the substrate thickness of the plate 33 is QD and the incident light wavelength is λ, a phase difference Δ determined by the following relational expression occurs. Thickness Q of λ / 4 plate 33
D is determined so that this phase difference Δ is π / 2 · (2m−1).

Δ = 2π · (n _e −n _o ) · QD / λ In the present embodiment, wavelength λ = 790 nm, extraordinary light refractive index n _e = 1.5477, and ordinary light refractive index n _o = 1.5388 ( However, the refractive index differs depending on the cutting angle of the substrate. Here, the substrate is cut in parallel with a plane including both the extraordinary optical axis and the ordinary optical axis.), And 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. 7 will be described. FIG. 9 is a layout diagram of a light receiving portion of an optical pickup for a phase-change optical disk according to an embodiment of the present invention. Reflected light 123
Enters the astigmatism generation hologram 10 formed of a reflection hologram on the second slope 41b. Reflected light 12
Reference numeral 3 shows astigmatism generated by the astigmatism generation hologram 10, and is further reflected by the reflection film 124 and the reflection film 125, and the return light of the main beam returns to the light receiving portion 38 on the light receiving element 36 and the side beam returns. The 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 36.

[0055]

According to the present invention, since the housing member of the integrated optical pickup is made of a metal material, it has a strong shielding effect against noise such as electromagnetic waves from the high frequency superposition circuit. Therefore, since noises resulting from these are not superimposed on various electric signals input and output from the optical pickup, it is possible to provide a high-performance optical pickup with a low noise level and an optical pickup for a phase-change optical disk. Becomes

Further, at least the light source, the light guide member and the light receiving means are housed between the base and the lid member, and at least one of N ₂ gas, inert gas and dry air is filled therein. By applying a predetermined current while applying a predetermined pressure between the base and the lid member and welding the base and the lid member, the base and the lid member can be more easily joined. Moreover, since the number of parts and the number of manufacturing steps can be reduced, the manufacturing cost of the optical pickup can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a packaging configuration 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 the optical pickup according to the 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 configuration diagram of an optical pickup for a phase-change optical disc according to an embodiment of the present invention.

FIG. 8 is a schematic view of a λ / 4 plate according to an embodiment of the present invention.

FIG. 9 is a layout view of a light receiving portion of an optical pickup for a phase change optical disc according to an embodiment of the present invention.

FIG. 10 is a sectional view of a hermetic seal according to an embodiment of the present invention.

FIG. 11 is a sectional view of a conventional optical pickup.

[Explanation of symbols]

1 Light Source 2 Submount 2a Electrode Surface 3 Block 3a Projection 3b End Face 4 Substrate 4a Hole 4b 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 Terminal 15 Cap 16 Cover member 16a Antireflection film 17 Gap 20 Outer ring metal 21 Insulator 22 Lead 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 section 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 Surfaces 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-6-251411 (JP, A) JP-A-61-243964 (JP, A) JP-A-6-203420 (JP, A) JP-A-6- 334269 (JP, A) JP-A-6-152067 (JP, A) JP-A-4-298830 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B ^7/ 12-7 / 22 G11B 11/10-11/105

Claims (3)

(57) [Claims] 1. A light source and a plurality of inclined surfaces that are inclined with respect to an incident direction of light emitted from the light source, and guide the light from the light source to the medium through the plurality of inclined surfaces and from the medium. Light guide member for guiding the light of the above to a predetermined position through the plurality of slopes, light receiving means for receiving the light and converting the received optical signal into an electric signal, Cu, Al, Fe metal materials, and FeNi Alloy, F
eNiCo made form <br/> at least any one material of the alloy, and the substrate for mounting the said light source the light guide member and the light receiving means, FeNiCo alloy, at least any one of FeNi Alloy An accommodating member formed of a metal material, having a light passage hole, and accommodating the light source, the light guide member, and the light receiving means, PbO.B2O3.ZnO-based crystalline glass, BK-7,
A cover member formed of any one of optical glass materials of Kovar glass and having an antireflection film formed on both surfaces thereof and joined to the light passage hole, and containing N2 gas or Ar, Ne, He An optical pickup characterized in that at least one kind of active gas is filled and the substrate and the cover member are joined together. Wherein by inserting a plurality of terminals connected to at least one of the light source or the light receiving means to the substrate
The optical pickup according to claim 1 , wherein the optical pickup is hermetically sealed . 3. A projection is provided on at least one of the substrate and the storage member to store the substrate and the storage member.
The optical pickup according to claim 1 or 2, wherein the member is welded .