JPH0512706A - Optical integrated circuit, optical integrated circuit for signal reproduction, optical integrated type pickup device, and optical disk device - Google Patents

Abstract

PURPOSE:To realize the optical integrated circuit or optical integrated circuit for signal reproduction which is small in size and lightweight, superior in mass- productivity, and low in price and has improved reliability and to realize the new type optical integrated type pickup device and optical disk device which are applied with those optical integrated circuits. CONSTITUTION:A transparent substrate 10 is molded out of transparent resin in a rectangular parallelepiped shape, and electronic components such as a laser element 11 and a multiple divisional photodiode 17 and optical components such as a hologram beam splitter 13, a hologram collimator lens 14, and an aspherical objective 15 are mounted integrally on both the top and reverse surfaces 10a and 10b of the transparent substrate or a slanting surface 20 formed on one end surface. The laser beam projected from the laser element 11 is reflected by said optical components to travel zigzag in the transparent substrate 10 and is converged on an optical disk 19 and its return light which is reflected by the optical disk 19 travels along the reverse path and is detected by the multiple divisional photodiode 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical integrated pickup used for reading information by, for example, focusing a laser beam on a fine spot light and irradiating it onto a disk or the like and detecting the reflected light. The present invention relates to an apparatus, in particular, an optical integrated pickup suitable for an optical pickup apparatus for reproducing a compact disc, an optical integrated circuit constituting the optical integrated pickup, an optical integrated circuit for reproducing a signal, and the optical integrated pickup. The present invention relates to an applied optical disk device.

[0002]

2. Description of the Related Art An optical pickup for reading signal information recorded on an optical disc such as a compact disc (CD) has a servo function for focusing and tracking. This is because the servo function causes the optical pickup to accurately follow mechanical fluctuations such as surface wobbling and eccentricity that accompany rotation of the optical disk.

FIG. 9 shows the structure of a conventional optical pickup. A semiconductor laser (LD) 3 as a light source is provided in a laser package 32 which is arranged below the optical disc 30 so as to face it.
1 is implemented. The light beam emitted from the semiconductor laser 31 is a diffraction grating 33 for generating three beams, a beam splitter 34, a collimator lens 35, and an objective lens 3.
It is condensed on the optical disk 30 via 6. Optical disc 3
The light beam reflected by 0 is deflected by 90 ° in the optical path by the beam splitter 34, and thereafter passes through the concave lens 37 and the focus detection cylindrical lens 38, and is detected by the multi-division light receiving element (PD) 39. A reproduction signal, a focus error signal, and a tracking error signal are obtained from this detection signal. Detection of these error signals is performed using the astigmatism method.

The objective lens 36 is an actuator A.
And is moved at a high speed in the optical axis direction and in the direction perpendicular to the track according to the error signal. These are called focus servo and tracking servo, respectively.

However, the conventional optical pickup shown in FIG. 9 has a large number of optical components of 8 points,
In addition, since each of them is an individual component, it is necessary to precisely adjust the optical axis and fix them on a robust substrate made of zinc die casting or the like. Therefore, a large number of man-hours are required for manufacturing, and there is a limit in downsizing and cost reduction.

Another conventional example of the optical pickup is a hologram type optical pickup in which a beam splitter uses a diffraction grating in order to reduce the number of components. FIG. 10 shows the configuration of this hologram type optical pickup.
A semiconductor laser 42 and a multi-divided light receiving element 43 are mounted on the same surface in a laser package 41, and a light beam emitted from the semiconductor laser 42 passes through a transparent glass 44, a collimator lens 45 and a projection lens 46, and an optical disc. Focused on 40. The light beam reflected by the optical disc 40 is guided to the multi-division light receiving element 43 through the transparent glass 44 and detected.

A diffraction grating 44a for generating three beams is formed on the surface of the transparent glass 44 located on the laser package 41 side. A diffraction grating 44 for a beam splitter that bends the return light from the optical disc 40 by diffraction on the surface located on the optical disc 40 side and guides it to the multi-split light receiving element 43.
b is formed.

According to this hologram type optical pickup, the number of parts can be halved as compared with the above optical pickup.
The number of adjustment points during manufacturing can be reduced. Therefore, there is an advantage that the number of manufacturing steps can be reduced and the manufacturing efficiency can be improved.

However, as shown in FIG. 10, this hologram pickup has a diffraction grating 44a for generating three beams and a diffraction grating 44 for a beam splitter on both sides.
Since it is necessary to form b, transparent glass (optical component block) having a large thickness dimension must be mounted on the laser package 41. For this reason, this portion becomes large, and there is a limit in reducing the size and thickness of the entire optical pickup.

[0010]

By the way, the above-mentioned 2
An optical pickup shown in FIG. 11 has been developed as an optical pickup that solves the drawbacks of the types of optical pickups. This optical pickup is called an optical waveguide type pickup, and focuses a light beam emitted from the semiconductor laser 51 on an optical disk 53 through an optical waveguide formed inside a transparent substrate 52 having a plate shape. Take a schematic configuration.

However, since the optical waveguide of this optical pickup is as thin as 1 μm or less, it is difficult to efficiently introduce the light beam from the semiconductor laser 51 into the optical waveguide. Therefore, at present, there is a limit in using it for an optical pickup.

The present invention solves the above-mentioned drawbacks of the prior art and provides a novel optical integrated pickup device which can be made compact and thin and which is suitable for optical disc pickups, particularly for compact disc optical pickups. The purpose is to do.

Another object of the present invention is to provide an optical integrated circuit and an optical integrated circuit for signal reproduction which can be expected to be used in an optical integrated pickup device.

Another object of the present invention is to provide an optical disc device using an optical integrated pickup device.

[0015]

The optical integrated circuit of the present invention comprises:
At least one optical element and at least one electronic element are mounted on the surface of a transparent substrate having a polyhedral structure so that light propagates inside the transparent substrate, thereby achieving the above object.

The signal reproducing optical integrated circuit of the present invention comprises:
A light beam propagates inside a transparent substrate having a polyhedral structure having at least a pair of parallel planes, and on the pair of parallel planes,
Optical components such as a beam splitter, collimator lens, focusing diffraction grating type and aspherical lens, and electronic components such as a semiconductor laser and a multi-divided light receiving element are integrally mounted, thereby achieving the above object. To be done.

An optical integrated pickup device can be realized by using the above optical integrated circuit or the signal reproducing optical integrated circuit.
Furthermore, an optical disc device using the optical integrated pickup device can be realized.

[0018]

As described above, on a pair of parallel surfaces of a transparent substrate having a polyhedral structure, optical components such as a beam splitter, a collimator lens, a focusing diffraction grating type and an aspherical lens, a semiconductor laser and a multi-divided light receiving element. When integrated with an electronic component such as an element, an optical integrated optical system in which a light beam emitted from a semiconductor laser is modulated by an optical diffraction grating inside a transparent substrate and propagates in a zigzag pattern is realized.

[0019]

EXAMPLES Examples of the present invention will be described below.

1 to 4 show an embodiment of an optical integrated circuit (optical integrated circuit for signal reproduction) of the present invention. This optical integrated circuit 1
The optical components and electronic components described later are integrally mounted on the upper and lower surfaces of the transparent substrate 10 having a rectangular parallelepiped shape. The transparent substrate 10 is formed by molding a transparent resin (PMMA) having a thickness of 2 mm into a rectangular parallelepiped shape.

Two kinds of hologram beam splitters (HBS) 13 having different pitches are formed on the upper surface 10a of the transparent substrate 10 at an intermediate portion in the longitudinal direction. An aspherical objective lens (OL) 15 is formed on the side of the hologram beam splitter 13, that is, at one end of the upper surface 10a.
Further, an inclined surface 20 is formed on the end surface of the transparent substrate 10 opposite to the position where the aspherical objective lens 15 is formed.

On the other hand, as shown in FIG. 4, a hologram collimating lens (HC) is provided on a portion of the lower surface 10b of the transparent substrate 10 which is below the aspherical objective lens 15.
L) 14 is formed. At positions separated from the hologram collimator lens 14 by an appropriate length in the longitudinal direction, 0th order, ± 1
Diffraction grating (3B) for forming three beams to generate the next diffracted light
H) 12 and the mirror 16 are provided opposite to each other.

The above-mentioned optical components are integrally molded at the same time as the transparent substrate 10 is molded. Alternatively, the upper and lower surfaces 10a, 10
It is also possible to use a female grating stamper for b. The positional relationship of the optical components formed on the upper and lower surfaces 10a and 10b of the transparent substrate 10 is as shown in FIG. Since this positional relationship is uniquely determined by the accuracy of the mold or the female grating stamper, it is possible to perform accurate positioning simply by managing the accuracy. Therefore, the complicated optical axis adjustment required in the above-mentioned conventional example becomes unnecessary. Therefore, it is convenient for improving mass productivity. Further, a large number of transparent resin plates are molded into a large piece at a time, and then a predetermined size (4 mm
If it is separated into (× 10 mm), a plurality of transparent substrates 10 including such optical components can be manufactured at the same time, which is more convenient for mass production. In addition, the transparent substrate 1
Since the material of No. 0 is resin, there is an advantage that the weight can be reduced.

On the other hand, a laser element (LD) 11 made of a semiconductor laser or the like is mounted on the inclined surface 20 of the transparent substrate 10. The laser element 11 is specifically the laser element 1
1 is mounted on the inclined surface 20 via a submount 18 made of a silicon substrate on which a circuit (not shown) for driving 1 is integrated. In addition, a multi-division photodiode (PD) 17 incorporating a signal processing integrated circuit (not shown) is mounted on the lateral side of the laser element 11. Laser element 1
If the 1- and multi-segment photodiodes 17 are arranged on the inclined surface 20 in such a state, the electrical connection mode can be simplified. Therefore, the number of electronic circuit terminals can be reduced and reliability can be improved.

The optical integrated pickup of the present invention is realized by the above-mentioned structure. The operation principle will be described below.
The laser beam emitted from the laser element 11 toward the inside of the transparent substrate 10 is divided into three diffracted lights of 0th order and ± 1st order by the diffraction grating 12 for forming three beams. These diffracted lights are reflected by the hologram beam splitter 13 and the hologram collimator lens 14, and then pass through the aspherical objective lens 15 and are condensed on the optical disk 19 located above the transparent substrate 10.

The light emitted from the hologram collimator lens 14 is collimated and emitted to the aspherical objective lens 15. The laser beam converged by the aspherical objective lens 15 is condensed on the optical disc 19 as spot light having a diameter of 1.6 μm.

The laser beam reflected by the optical disk 19 is guided to the multi-divided photodiode 17 along the path opposite to the above, and is photoelectrically converted by the multi-divided photodiode 17.

Of the electric signals photoelectrically converted, the electric signal corresponding to the 0th order light is used for signal detection of the optical disk 19, that is, for reading the information written on the optical disk 19. Further, the ± 1st order lights located on both sides of the 0th order light are used as a focus error signal and a tracking error signal. The 0th-order light and the ± 1st-order lights are reflected by the hologram beam splitter 13 having two kinds of pitches when returning as reflected beams, and the respective light beams 2
2, 22 ', that is, separated, and then reflected by the mirror 16 and detected by the multi-segment photodiode 17.

Instead of the mirror 16, it is also possible to form a reflection mirror with a deep diffraction grating. In this way, since the reflection mirror has a function as an analyzer, it is possible to detect the plane of polarization associated with the Kerr effect of a medium such as a magneto-optical disk.

FIG. 5 shows another embodiment of the optical integrated circuit of the present invention. In this embodiment, the transparent substrate is provided on the outer surface of the transparent substrate 10 except the positions where the optical components and electronic components are arranged. The stray light prevention layer 60 is formed by coating or resin coating an absorber or an antireflection film having an absorption band with respect to the light wavelength of the laser beam propagating inside 10.

The formation of the stray light prevention layer 60 can prevent stray light in the transparent substrate 10 and has the following advantages.
That is, in the above-described transparent substrate 10, the laser beam propagating in the transparent substrate 10 is much affected by the high-order diffracted light of 0th order, ± 1st order, ± 2nd order ... Stray light is generated. Then, the stray light is detected as a noise component by the multi-division photodiode 17, resulting in erroneous detection. Therefore, if the stray light preventing layer 60 is formed as described above and stray light is absorbed thereby to prevent the occurrence thereof, there is no risk of erroneous detection, and accurate information reading with a good S / N ratio can be performed. You can do it.

The stray light prevention layer 60 is specifically formed as follows. That is, when the optical disc 19 is a compact disc, since the laser element 11 having a light wavelength of 780 nm is mounted, it is formed by coating a coating film mixed with carbon fine powder, silicon fine powder, GaAs fine powder and the like. It Instead of coating, it may be formed by using a vapor deposition method. Instead of absorbing stray light, a non-reflective coating film may be formed on the outer surface of the transparent substrate 10 to allow stray light to escape to the outside. Also with this method, it is possible to read information with a good S / N ratio and high accuracy.

FIG. 6 shows another embodiment of the optical integrated circuit of the present invention different from that of FIG. In this embodiment, the focusing coil 70 having the tracking coil 71 attached is fixedly adhered to the optical integrated circuit 1 having the above-described configuration, whereby the optical integrated circuit 1 and the actuator coil are integrated. With such a configuration, it is possible to realize an optical integrated pickup that is small in size, lightweight, and excellent in mass productivity.

The optical integrated circuit 1 in each of the above embodiments
Is a so-called signal reproduction optical integrated circuit that detects the return light from the optical disc 19, but can also be used as a write-only optical integrated circuit for writing information to the optical disc, and can also be written and read. It can be expected to be used as an optical integrated circuit.

FIG. 7 and FIG. 8 show a concrete embodiment when the optical integrated circuit 1 of the present invention is applied to an optical integrated pickup. The optical integrated pickup 2 includes a sub-mount 18 and a multi-divided photodiode 17 on which optical components such as a hologram beam splitter 13 and an aspherical objective lens 15 and a laser element (laser chip) 11 similar to those described above are mounted.
The following actuator is integrated with the transparent substrate 10 provided with.

This actuator is provided with a focusing coil 70 to which a tracking coil 71 is attached. The focusing coil 70 is provided with thin and lightweight glass epoxy substrates 72 and 72 for reinforcement, which are shaded in the figure. It is integrated with the transparent substrate 10 shown. A strong permanent magnet 73 containing a rare earth element is arranged in the air-core portion of the focusing coil 70. A similar permanent magnet 73 is also arranged outside the side of the focusing coil 70 to which the tracking coil 71 is attached.

The permanent magnets 73, 73 are fixed by the yokes 74, 74. The yokes 74, 74 are made of a material having high magnetic permeability. As an example, in this embodiment, the lower substrate 75 on which the transparent substrate 10 and the like are mounted is also formed of iron. The fixing of the permanent magnets 73, 73 is specifically performed as follows. Cut and raise a part of the lower substrate 75,
Next, the cut-and-raised portion is bent into a U shape as shown in FIG. 8 to form yokes 74, 74, and the permanent magnets 73, 73 are fixed to the yokes 74, 74 with an adhesive or the like. According to such a fixing structure, the magnetic flux leaking from the permanent magnets 73, 73 to the outside can be suppressed by the yokes 74, 74, that is, the magnetic shield can be performed.

Here, the tracking coil 71
Is arranged so that its coil center coincides with the edges of the permanent magnets 73, 73. In addition, the transparent substrate 1
0 and the focusing coil 70 are integrated with each other. Glass epoxy substrates 72 and 72 are soldered to columns 77 and 77 erected on the lower substrate 75 via wires 76 and 76 made of thin and spring-like piano wire or the like. Be fixed using.
A total of four wires 76 are used, two each at the top and bottom.

These wires 76 are used not only for mechanically holding the transparent substrate 10 but also for supplying a current to the focusing coil 70 and the tracking coil 71. Therefore, one end of the wire 76 is connected to the flexible substrate 78 via the support column 77 formed of an insulating material. The flexible substrate 78 is also connected to the laser element 11 and the multi-segment photodiode 17. Further, the flexible substrate 78 is connected to an insulating substrate 79 arranged at one end of the lower substrate 75. It is preferable that the flexible substrate 78 has a spring property as weak as possible, and it is necessary to allow a certain amount of margin for its deformation.

According to the optical integrated pickup 2 having the above-mentioned structure, it is possible to realize a completely new type of optical pickup which is small in size, light in weight and excellent in mass productivity, which has never been obtained. Further, by applying this optical integrated pickup, an optical disk device having the same advantages as described above can be realized.

[0041]

The optical integrated circuit of the present invention as described above has a structure in which an optical component and an electronic component are integrally mounted on the surface of a resin-molded transparent substrate. It is possible to realize a new type of optical integrated circuit that can be improved in price and reliability. Further, an optical integrated circuit for reproducing an optical signal having a similar effect can be realized by mounting an optical component such as a light receiving element on the optical integrated circuit in the same manner.

By applying the optical integrated circuit or the signal reproducing optical integrated circuit, it is possible to realize a new type of optical integrated pickup device having the same effect as described above.
Furthermore, if the optical integrated pickup device is applied, a new type optical disc device having the same effect can be realized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an optical integrated circuit of the present invention.

FIG. 2 is a side view of the optical integrated circuit of the present invention.

FIG. 3 is a plan view of the optical integrated circuit of the present invention.

FIG. 4 is a bottom view of the optical integrated circuit of the present invention.

FIG. 5 is a perspective view showing another embodiment of the optical integrated circuit of the present invention.

FIG. 6 is a view showing another embodiment of the optical integrated circuit of the present invention.

FIG. 7 is a plan sectional view showing an optical integrated pickup of the present invention.

FIG. 8 is a side sectional view showing an optical integrated pickup of the present invention.

FIG. 9 is a side view showing a conventional example of an optical pickup.

FIG. 10 is a side view showing another conventional example of the optical pickup.

FIG. 11 is a perspective view showing another conventional example of an optical pickup.

[Explanation of symbols]

1 Optical integrated circuit 2 Optical integrated pickup 10 Transparent substrate 10a upper surface of transparent substrate 10b Transparent substrate bottom surface 11 Laser device 12 Diffraction grating for three beams 13 Hologram beam splitter 14 Hologram collimating lens 15 Aspherical objective lens 16 mirror 17 Multi-segment photodiode 19 optical disc 20 slope 60 stray light layer 70 Focusing coil 71 Tracking coil 72 Glass epoxy substrate 73, 73 Permanent magnet 75 Lower substrate

Continued front page    (72) Inventor Shochika Kato             22-22 Nagaikecho, Abeno-ku, Osaka-shi             Within the corporation (72) Inventor ▲ Yoshi ▼ Tomohiko Ta             22-22 Nagaikecho, Abeno-ku, Osaka-shi             Within the corporation (72) Inventor Toshimasa Hamada             22-22 Nagaikecho, Abeno-ku, Osaka-shi             Within the corporation (72) Inventor Matsui             22-22 Nagaikecho, Abeno-ku, Osaka-shi             Within the corporation

Claims (17)

[Claims] 1. An optical integrated circuit in which at least one optical element and an electronic element are mounted on the surface of a transparent substrate having a polyhedral structure, and light is propagated inside the transparent substrate. 2. The optical integrated circuit according to claim 1, wherein the transparent substrate is made of a thermoplastic resin or glass having a high light transmittance. 3. An absorption layer for absorbing stray light trapped inside the transparent substrate or a transmissive layer for escaping the stray light to the outside is provided on a portion of the transparent substrate excluding the positions where the optical element and the electronic element are disposed. The optical integrated circuit according to claim 1 or 2. 4. A light beam propagates inside a transparent substrate having a polyhedral structure having at least a pair of parallel surfaces, and a beam splitter, a collimator lens, a diffraction grating type for focusing and an aspherical surface on the pair of parallel surfaces. An optical integrated circuit for signal reproduction in which optical components such as a lens and electronic components such as a semiconductor laser and a multi-divided light receiving element are integrally mounted. 5. An optical integrated circuit for signal reproduction according to claim 4, wherein the transparent substrate is made of a thermoplastic resin or glass having a high light transmittance. 6. Optical components such as the beam splitter, collimating lens, focusing diffraction grating type and aspherical lens are integrally formed on both the front and back surfaces of the transparent substrate by using a molding technique including a marking technique. An optical integrated circuit for signal reproduction according to claim 4. 7. An optical integrated circuit for signal reproduction according to claim 4, wherein said transparent substrate has an inclined surface on its end face, and a laser element and a light receiving element are disposed on said inclined surface. 8. An optical integrated circuit for signal reproduction according to claim 7, wherein a driving integrated circuit for driving the laser element and a signal processing integrated circuit for processing a detection signal of the light receiving element are mounted on the transparent substrate. 9. An absorption layer for absorbing stray light trapped inside the transparent substrate or a transmissive layer for escaping the stray light to the outside is provided on a portion of the transparent substrate other than the positions where the optical component and the electronic component are disposed. An optical integrated circuit for signal reproduction according to claim 4, claim 5, claim 6, claim 7 or claim 8. 10. An optical integrated pickup device in which a magnetic circuit for servo is provided in parallel with the optical integrated circuit according to claim 1. 11. An integrated optical pickup device according to claim 10, further comprising a driving integrated circuit for driving the servo magnetic circuit. 12. An optical integrated pickup device comprising the signal reproducing optical integrated circuit according to claim 4 and a servo magnetic circuit provided in parallel. 13. The optical integrated pickup device according to claim 12, further comprising a driving integrated circuit for driving the servo magnetic circuit. 14. An optical integrated pickup device in which the optical integrated circuit according to claim 1 is mounted on a biaxial actuator having a focus servo function and a tracking servo function. 15. An optical integrated pickup device in which the optical integrated circuit according to claim 4 is mounted on a biaxial actuator having a focus servo function and a tracking servo function. 16. An optical disk device comprising the optical integrated pickup device according to claim 14. 17. An optical disc device comprising the optical integrated pickup device according to claim 15.