JPH10124922A - Optical pickup device and disk player device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the optical pickup device as a small-sized and high performance optical pickup device using a light emitting and receiving element (laser coupler) capable of performing good recording and reproducing operation on a magneto-optical recording medium. SOLUTION: Prisms to be disposed on photodetectors 11, 12 and 13 are formed of a birefringent crystal material, and the photodetector 13 for receiving an extraordinary beam is formed in a position shifted in the lateral direction to be corresponding to the so-called walk-off of the extraordinary beam. A tracking error signal TRK is detected by an intensity distribution of spots formed by reflecting beams on light receiving surfaces of the individual photodetectors 11, 12 and 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for writing and reading information signals to and from a magneto-optical recording medium such as an optical disk and a magneto-optical disk, and to an optical disk and a magneto-optical disk provided with the optical pickup device. On the other hand, it belongs to the technical field related to a disc player device for recording and reproducing information signals.

[0002]

2. Description of the Related Art Hitherto, optical recording media such as optical disks (so-called pit disks, phase-change disks, rewritable disks, etc.) and magneto-optical disks have been proposed. Such an optical recording medium has a transparent substrate and a signal recording layer formed on the substrate. In optical disks and magneto-optical disks, the substrate is formed as a disk-shaped disk substrate. Also, in this optical disk and magneto-optical disk, in the signal recording layer,
The information signal is recorded along a substantially concentric spirally formed recording track.

As shown in FIG. 11, there has been proposed an optical pickup device for writing and reading information signals to and from a magneto-optical disk 101 as such an optical recording medium. This optical pickup device has a semiconductor laser 201 as a light source, and a light beam emitted from the semiconductor laser 201 is focused on a signal recording surface of the magneto-optical disk 101, that is, a surface portion of the signal recording layer 102 by an objective lens 205. It is configured to irradiate. The luminous flux emitted from the semiconductor laser 201 is divided into a grating (diffraction grating) 202 and a beam splitter 2.
The light is guided to an objective lens 205 via the collimator lens 03 and the collimator lens 204. The grating 202 enables detection of a tracking error signal described later.

In this optical pickup device, reflected light of the light beam irradiated on the signal recording surface by the signal recording surface is detected by a photodetector (PD: photodiode) 2.
09 to the magneto-optical disk 10
The reading of the information signal recorded on the one signal recording layer 102 and the detection of an error signal for maintaining the light flux on the signal recording surface, that is, a focus error signal and a tracking error signal are performed.

[0005] The reflected light returns to the beam splitter 203 via the objective lens 205 and the collimator lens 204. This reflected light is reflected by the beam splitter 203 and enters the photodetector 209 via the Wollaston prism 207 and the multi-lens 208. The Wollaston prism 207 is a prism that splits an incident light beam according to the polarization component of the light beam. The multi-lens 208 is a lens whose entrance surface is a cylindrical (cylindrical) surface and whose exit surface is a concave surface. The multi-lens 208 generates astigmatism for detecting a focus error signal in the incident light beam, and generates the incident light beam. Is a lens that moves the light-condensing point to the rear side.

The focus error signal is a signal indicating the distance between the focal point of the light beam and the signal recording surface in the optical axis direction of the objective lens 205. In the optical pickup device, the focus error signal is set to 0 so that FIG.
As shown by the middle arrow F, the operation of moving the objective lens 205 in the optical axis direction of the objective lens 205, that is, the focus servo operation is performed.

[0007] The tracking error signal is a signal indicating the distance in the direction orthogonal to the tangent of the recording track to the recording track and the optical axis of the objective lens 205, that is, in the radial direction of the magnetic optical disk 101. is there. In the optical pickup device, as shown by an arrow T in FIG. 11, the operation of moving the objective lens 205 in a direction perpendicular to the optical axis of the objective lens 205, ie, the tracking servo, so that the tracking error signal becomes zero. The operation is performed.

Conventionally, a read-only optical disk,
For example, as an optical pickup device used for reproducing a pit disk such as a so-called “CD” (Compact Disc), an optical pickup device using an integrated light emitting / receiving element as shown in FIG. 12 is employed.

The optical pickup device 210 includes an objective lens 211, optical path bending mirrors 212 and 213, and a light receiving / emitting element 214. The light beam emitted from the light receiving / emitting element 214 is used to convert the light flux from the light path bending mirror 212, 213 and the objective lens 211, the optical disk (CD) 10
Focus and focus on the signal recording surface of No. 3.

As shown in FIG. 13, the light receiving / emitting element 214 is constituted by integrating a light emitting element and a light receiving element as an integrated optical block. The light emitting / receiving element 214 has a configuration in which a second semiconductor substrate 216 is mounted on a first semiconductor substrate 215, and a semiconductor laser chip 217 as a light emitting element is mounted on the second semiconductor substrate 216. I have.

On a first semiconductor substrate 215 in front of the semiconductor laser chip 217, a trapezoidal prism 2 having an inclined surface (an optical path branching surface) on the semiconductor laser chip 217 side is provided.
A non-polarizing semi-transmissive film 218a as a beam splitter is formed on the optical path branching surface. The prism 218 has a total reflection film 218b formed on its top surface, and a non-polarized semi-transmissive antinode 218c formed on its bottom surface.

Thus, the prism 218 reflects the light beam emitted from the semiconductor laser chip 217 on the optical path branch surface and emits the light beam to the outside of the light receiving / emitting element 214. The luminous flux emitted from the light receiving / emitting element 214 is shown in FIG.
As shown in FIG. 2, the light enters the objective lens 211 via the mirrors 213 and 212 for bending the optical path.
1 focuses and focuses on the signal recording surface of the optical disk 103.

The reflected light beam reflected by the signal recording surface of the optical disk 101 passes through the objective lens 211 and the optical path bending mirrors 212 and 213 from the inclined surface of the prism 218 of the light receiving / emitting element 214 into the prism 218. The incident light is sequentially reflected on the bottom surface portion and the top surface portion of the prism 218, and is emitted to the lower side of the prism 218 at two places on the bottom surface portion of the prism 218.

The first and second photodetectors 219a and 219a are located on the top surface of the first semiconductor substrate 215 at positions where light emitted from two places on the bottom surface of the prism 218 is received.
219b are formed.

As shown in FIG. 14, the photodetectors 219a and 219b are divided into three light receiving sections (a, b, c, d), ( e, f, g, h). As a result, the photodetectors 219a and 219b detect the signal RF read from the optical disc 101. The light detection output signal from each divided light receiving unit is Sa,
Assuming that Sb, Sc, Sd, Se, Sf, Sg, and Sh, RF = Sa + Sb + Sc + Sd + Se + Sf + Sg + S
h In the photodetectors 219a and 219b, a so-called push-pull (Push-pull) among the four divided sensor elements is used.
-Pull) method to obtain the tracking error signal T by taking the difference between the detection signals from the two divided light receiving sections on both sides.
RK is detected.

TRK = (Sa + Se)-(Sd + Sh) Further, in the photodetectors 219a and 219b, based on the detection signals from the central sensor element and the two sensor elements on both sides by the so-called differential three division method. The focus error signal FCS is detected.

FCS = ｛(Sa + Sd)-(Sb + S
c) {-{(Se + Sh)-(Sf + Sg)} For the tracking error signal TRK, the DC offset caused by the movement (field movement) of the objective lens 211 in the direction orthogonal to the optical axis due to the tracking servo operation is cancelled. To do so, the so-called TPP (Top
hold Push-Pull) method has been proposed.

That is, in the push-pull system,
As shown in FIG. 15, the tracking error signal TRK is obtained by comparing the intensity distributions of both side portions β ₁ and β ₂ of the light spot α formed on the light receiving surface of the photodetector 219 by the light beam reflected from the optical disk 103. I have. When the light beam emitted from the objective lens 211 is irradiated on the recording track of the optical disc 103, the intensities of both side portions β ₁ and β ₂ are equal. When the irradiation position of the light beam emitted from the objective lens 211 deviates from the recording track, FIG.
As shown in FIG. 6, the intensities of both side edge portions β ₁ and β ₂ are different from each other. However, if the objective lens 211 is moved to move the field of view, the light spot α itself on the light receiving surface of the photodetector 219 moves, and a DC offset occurs in the tracking error signal TRK.

FIG. 1 shows the detection output E from the divided light receiving section E that has received the area β ₁ on one side of the light spot α.
As shown in FIG. 7, the peak of the RF envelope waveform of the detection signal E changes in a range indicated by an arrow a in FIG. What is used for tracking error detection in the push-pull method is the A signal obtained by passing the RF envelope of the detection output E through a low-pass filter (LPF). The offset of the A signal changes in a range indicated by an arrow b in FIG. 17 according to the visual field movement. Therefore, the DC offset can be canceled by subtracting the offset change b from the A signal. Where b =
When a constant K (<1) serving as Ka is determined, the signal from which the offset has been canceled is represented by (A signal-Ka). The divided light receiving portion F that has received the area β ₂ on the other side of the light spot α
The same can be said for the detected output F. The TPP method obtains the tracking error signal TRK based on the offset-cancelled signal in this manner.

That is, in this TPP method, as shown in FIG. 18, the top hold of the detection output E from the divided light receiving section E which has received the area β ₁ on one side of the light spot α is obtained, and the coefficient K is calculated. The TPP (E) signal is obtained by subtracting the detection output E from this signal. On the other hand, a top hold of the detection output F from the divided light receiving portion F that has received the area β ₂ on the other side of the light spot α is obtained, multiplied by a coefficient K, and the detection output F is subtracted from this signal to obtain TPP (F). Find the signal. Then, TPP (F) is obtained from the signal TPP (E).
Is subtracted to obtain a TPP signal (TPP = TPP
(E) -TPP (F)).

As a method for eliminating the offset of the tracking error signal in the above-mentioned groove disk having the wobble which is the magneto-optical disk 101, it is proposed to use a change in the wobble component.

[0022]

In the above-described optical pickup apparatus for a magneto-optical recording medium, a large number of optical devices such as a semiconductor laser 201, a photodetector 209, a beam splitter 203, etc. Must be individually mounted and assembled within
The steps of manufacturing, assembling, and adjusting each optical device are complicated, and it is difficult to reduce the size, improve the performance, and increase the durability.

The optical pickup device constituted by using the light receiving and emitting elements as described above can easily perform an assembling process and an adjusting process, and can achieve miniaturization, high performance, and high durability. It uses a so-called non-polarizing optical system, and cannot be used to write and read information signals to and from a magneto-optical recording medium.

Therefore, in order to apply the present invention to an optical pickup device for recording / reproducing a magneto-optical disk, for example, FIG.
As shown in FIG. 2, a parallel plate-shaped half-wave plate 18d is provided between the prism 18 and the first semiconductor substrate 15 on the first semiconductor substrate 15, and a non-polarization semi-transmissive film as a beam splitter is provided. Instead of the 218c, it is necessary to use a P beam splitter (polarized beam splitter) 18e having an analyzer function.

However, as described above, a P-beam splitter 18 is simply used as a beam splitter in a conventional light receiving / emitting element.
When e is used, the central value of the incident angle of the light beam incident on the part to be the P beam splitter becomes a small angle of about 21 °, so that a beam splitter made of a multilayer film cannot be used, and the prism 18 cannot be used. However, there is a problem that the number of parts increases, the manufacturing process becomes complicated, and the manufacturing cost and the assembly cost increase.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and aims at simplifying the assembling process and the adjusting process, and attaining a reduction in size, performance, and durability. It is an object of the present invention to solve the problem of providing an optical pickup device that can write and read information signals to and from a magneto-optical recording medium.

Another object of the present invention is to solve the problem of providing a disk player device having good recording / reproducing characteristics for a magneto-optical recording medium by providing the above-described optical pickup device.

[0028]

In order to solve the above-mentioned problems, an optical pickup device according to the present invention comprises a light source provided on a semiconductor substrate, a first signal-reading photodetector,
A second signal-reading photodetector and a third signal-reading photodetector; a bottom surface and a top surface formed of a birefringent material and parallel to each other; The optical axis in the case where the birefringent material is a uniaxial crystal, or the difference from the intermediate refractive index among three refractive index orientations in the case where the birefringent material is a biaxial crystal. The direction corresponding to the larger refractive index is set in a plane perpendicular to the normal line of the top surface and the bottom, the bottom is positioned on each signal reading photodetector, and the inclined surface faces the light source. And a prism bonded to the upper surface of the semiconductor substrate. The prism emits a light beam emitted from a light source, reflected by an inclined surface, and irradiated on a recording track on a signal recording surface of a magneto-optical recording medium. Reflected on the surface The reflected light flux, which is a light flux, is returned to the inclined surface portion, and the reflected light flux enters the prism through the inclined surface portion to be branched into two groups of light beams, and a part of these reflected light beams passes through the bottom portion. Of the reflected light beams reflected by the bottom surface portion, reflected by the top surface portion, and then transmitted through the bottom surface portion to output the second and third signals. The light-receiving surface of the first signal-reading photodetector is divided into at least two divided light-receiving sections, and the differential light output signals from these divided light-receiving sections are output. Thus, a tracking error signal corresponding to the distance between the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium and the recording track is detected.

The optical pickup device according to the present invention comprises a light source, a first signal reading photodetector, a second signal reading photodetector, and a third signal reading photodetector disposed on a semiconductor substrate.
A signal reading photodetector, and a bottom surface portion and a top surface portion which are formed of a birefringent material and which are parallel to each other, and one end portion is formed as a light beam splitting surface and an inclined surface portion inclined with respect to the bottom surface portion. Is the optical axis in the case where is a uniaxial crystal, or the direction corresponding to the refractive index of the one having a larger difference from the intermediate refractive index among the three refractive index directions in the case where the birefringent material is a biaxial crystal. A prism set in a plane perpendicular to the normal line of the top surface portion and the bottom surface portion, the bottom surface portion is positioned on each signal readout photodetector, and the inclined surface portion is bonded to the upper surface portion of the semiconductor substrate with the inclined surface portion facing the light source. The prism is a light beam emitted from a light source, reflected by an inclined surface portion, and irradiated on a recording track on a signal recording surface of a magneto-optical recording medium, the reflected light beam being a light beam reflected on the signal recording surface. On the slope Then, the reflected light flux enters the prism through the inclined surface portion and is branched into two groups of light beams, and a part of these reflected light beams is transmitted to the first signal reading photodetector through the bottom surface portion. After reflecting the light beam reflected by the bottom surface portion of the reflected light beams by the top surface portion, the light beam is guided to the second and third signal reading photodetectors through the bottom surface portion, The light-receiving surface of the second and / or third signal-reading photodetector is divided into at least two divided light-receiving portions, and a magneto-optical recording medium is obtained by a differential light output signal from these divided light-receiving portions. The tracking error signal corresponding to the distance between the irradiation position of the light beam on the signal recording surface and the recording track is detected.

According to the present invention, in the optical pickup device, the light receiving surface of the first signal readout photodetector is:
Divided into at least two divided light receiving sections, the divided light receiving section of the first signal reading photodetector, the divided light receiving section of the second signal reading photodetector, and / or the third signal reading photodetector. The tracking error signal is detected by the differential of the optical output signal from the divided light receiving section of the photodetector.

The disk player device according to the present invention comprises a medium holding mechanism for holding a magneto-optical recording medium, a light source provided on a semiconductor substrate, a first signal reading photodetector, and a second signal reading device. An optical axis in the case where the reading photodetector and the third signal reading photodetector are formed of a birefringent material, have a parallel bottom surface portion and a top surface portion, and the birefringent material is a uniaxial crystal, or In the case where the birefringent material is a biaxial crystal, the direction corresponding to the refractive index having a larger difference from the intermediate refractive index among the three refractive index directions is perpendicular to the normal line of the top surface portion and the bottom surface portion. One end part is set in the plane, and one end part is formed as an inclined surface part inclined with respect to the bottom surface part as a light beam splitting surface, the bottom surface part is positioned on each of the signal reading photodetectors, and the inclined surface part is directed toward the light source. Bonded to the top surface of the semiconductor substrate A light beam emitted from a light source, reflected by the inclined surface portion, and condensed on the signal recording surface of the magneto-optical recording medium by the light condensing means is reflected by the light condensing means via the light condensing means. The reflected light flux is returned to the inclined surface portion, enters the prism through the inclined surface portion, is branched into two groups of light beams, and a part of these reflected light beams is transmitted through the bottom surface portion to generate the first signal. The second and third signal readout light detectors are guided to the readout light detector, and the light flux reflected by the bottom surface portion of the reflected light beams is reflected by the top surface portion and then transmitted through the bottom surface portion. And a calculation circuit for performing a calculation based on the light detection output output from each signal reading light detector, wherein the light receiving surface of the first signal reading light detector has at least two divided light receiving surfaces. It is divided into a light receiving section and an arithmetic circuit , A differential of the optical output signal from these light receiving section is obtained by a detecting a tracking error signal corresponding to the distance between the recording track irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium.

Further, the disk player device according to the present invention has a medium holding mechanism for holding a magneto-optical recording medium, a light source disposed on a semiconductor substrate, a first signal reading photodetector, and a second signal reading device. An optical axis in the case where the reading photodetector and the third signal reading photodetector are formed of a birefringent material, have a parallel bottom surface portion and a top surface portion, and the birefringent material is a uniaxial crystal, or In the case where the birefringent material is a biaxial crystal, the direction corresponding to the refractive index having a larger difference from the intermediate refractive index among the three refractive index directions is perpendicular to the normal line of the top surface portion and the bottom surface portion. One end part is set in the plane, and one end part is formed as an inclined surface part inclined with respect to the bottom surface part as a light beam splitting surface, the bottom surface part is positioned on each of the signal reading photodetectors, and the inclined surface part is directed toward the light source. Bonded to the top surface of the semiconductor substrate A light beam emitted from a light source, reflected by the inclined surface portion, and condensed on the signal recording surface of the magneto-optical recording medium by the light condensing means is reflected by the light condensing means via the light condensing means. The reflected light flux is returned to the inclined surface portion, enters the prism through the inclined surface portion, is branched into two groups of light beams, and a part of these reflected light beams is transmitted through the bottom surface portion to generate the first signal. The second and third signal readout light detectors are guided to the readout light detector, and the light flux reflected by the bottom surface portion of the reflected light beams is reflected by the top surface portion and then transmitted through the bottom surface portion. And a calculation circuit for performing a calculation based on the light detection output output from each of the signal readout photodetectors, and the light receiving surface of the second and / or third signal readout photodetector is provided. Divided into at least two light-receiving parts Ri, arithmetic circuit, a differential of the optical output signal from the divided light receiving portions,
This is to detect a tracking error signal corresponding to the distance between the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium and the recording track.

[0033]

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

In this embodiment, as shown in FIG. 1, an optical pickup device according to the present invention is configured as a device for writing and reading information signals using a magneto-optical disk 101 as a magneto-optical recording medium. Things.
The magneto-optical disk 101 is made of polycarbonate (Polycarbonate).
carbonate) and polymethyl methacrylate (Polymethylm
It has a disk-shaped disk substrate made of a transparent material such as ethacrylate) and a signal recording layer 102 formed on the disk substrate. This signal recording layer 1
Numeral 02 is formed from a magnetic material film. The surface portion of the signal recording layer 102 bonded to the disk substrate is a signal recording surface.

The optical pickup device according to the present invention includes a light emitting / receiving element 1 as shown in FIG. A laser beam is emitted from the light emitting / receiving element 1. The laser beam emitted from the light emitting / receiving element 1 is passed through the bending mirrors 3 and 4 and is focused by an objective lens 5 which is a condensing means constituting a disc player device described later.
The light is focused on the signal recording surface of the magneto-optical disk 101 through the disk substrate.

As shown in FIG. 2, the light receiving and emitting elements include a semiconductor laser chip 8 serving as a light source, first to third signal reading photodetectors 11 (PD1), 12 (PD2) and 13
(PD3) is provided with the first semiconductor substrate 6 disposed and formed on the upper surface portion.

The semiconductor laser chip 8 is provided on the upper surface of a second semiconductor substrate (heat sink) 7 provided on the upper surface of the first semiconductor substrate 6. The signal reading photodetectors 11, 12 and 13 are formed on the surface of the first semiconductor substrate 6.

The semiconductor laser chip 8 emits a light beam parallel to the upper surface of the first semiconductor substrate 6 toward the side where the signal reading photodetectors 11, 12, 13 are provided. The luminous flux emitted from the semiconductor laser chip 8 is
The cross-sectional shape is a divergent light beam having an elliptical shape, and the parallel divergence angle θ // in the direction parallel to the bonding surface is larger than the vertical divergence angle θL in the direction perpendicular to the bonding surface of the semiconductor layer in the semiconductor laser chip 8. narrow. The semiconductor laser chip 8
Is a so-called self-sustained pulsation type semiconductor laser, and when the light output of the emitted light beam is increased,
The parallel divergence angle θ // becomes narrow. This semiconductor laser chip 8
Are arranged such that the direction of the parallel divergence angle θ // is parallel to the surface of the first semiconductor substrate 6.

This optical pickup device has a top surface portion 2b and a bottom surface portion 2c which are parallel to each other, and a prism having one end portion formed as an inclined surface portion 2a inclined with respect to the bottom surface portion 2c which becomes a light beam splitting surface. Two. The prism 2 has a plurality of signal reading photodetectors 11, 12, and 13.
It is located on the first semiconductor substrate 6 with the bottom surface portion 2c joined to the upper surface portion of the first semiconductor substrate 6. The inclined surface 2a has an inclination angle of 4 with respect to the bottom surface.
5 °. A polarizing beam splitter (PBS) made of, for example, a dielectric multilayer film is provided on the inclined surface 2a.
A film 9 is formed.

The prism 2 is formed of a uniaxial crystal or a biaxial crystal which is a birefringent material. As the uniaxial crystal, for example, LN (LiNbO ₃ ) can be used. Further, as a biaxial crystal, for example,
KTP (KTiOPO ₄ ) can be used. Further, as the uniaxial crystal, for example, YVO ₄ can be used.

The uniaxial crystal has a refractive index in the three-dimensional direction, that is, a refractive index in each of the three refractive index directions.
_Assuming that _x , _ny , and _nz , _nx = _ny < _nz or _nx < _ny = _nz is a crystal, and a biaxial crystal is _nx < _ny < The crystal is _nz .

When the crystal material forming the prism 2 is a uniaxial crystal, the optical axis (crystal axis) is perpendicular to the normal of the reflection surface (ie, the top surface and the bottom surface) in the prism 2. It is set in the plane. And this prism 2
Is a biaxial crystal, the direction corresponding to the refractive index having the larger difference from the intermediate refractive index among the refractive index directions of the crystal is determined by the reflection surface in the prism 2 (that is, the reflection surface). , The top surface and the bottom surface).

In the prism 2, a light beam emitted from the semiconductor laser chip 8 is incident on the inclined surface 2a. The luminous flux from the semiconductor laser chip 8 is applied to the inclined surface 2a.
It is incident in the S-polarized state. That is, the polarizing beam splitter film 9 on the inclined surface 2a is configured to reflect most of the light beam from the semiconductor laser chip 8 and transmit most of the light beam reflected from the magneto-optical disk 101. The light beam reflected by the polarizing beam splitter film 9 is deflected in a direction perpendicular to the surface of the first semiconductor substrate 6, and is emitted from the light emitting / receiving element.

The light beam emitted from the light receiving / emitting element 1 is incident on the objective lens 5 as described above. As shown in FIG. 10, the objective lens 5 is supported by an objective lens driving mechanism 19 described later (in FIG. 10, the light beam before being incident on the objective lens 5 is transmitted to the collimator lens 16). To form a parallel light beam).
The objective lens driving mechanism 19 causes the objective lens 5 to face the signal recording surface of the magneto-optical disk 101. The objective lens 5 focuses the incident light beam on the signal recording surface of the magneto-optical disk 101.

The reflected light beam, which is a light beam reflected by the signal recording surface of the magneto-optical disk 101, includes a magneto-optical signal component whose polarization plane has been rotated by the so-called Kerr effect. The reflected light flux passes through the polarizing beam splitter film 9 via the objective lens 5, enters the prism 2 from the inclined surface 2 a of the prism 2, and reaches the bottom 2 c of the prism 2.

If the transmittance Tp for P-polarized light is selected to be larger than the transmittance Ts for S-polarized light, the polarizing beam splitter film 9 will have a so-called enhancement function of a magneto-optical signal, and The S / N ratio is improved, and more accurate detection of a magneto-optical signal can be performed.

As shown in FIG. 4, a semi-transmissive film 10 is selectively applied to the region of the bottom surface 2c of the prism 2 where the reflected light beam enters (the second and third signal reading photodetectors 1 and 2).
As shown in FIG. 2, a first signal-reading photodetector is formed on the upper surface of the first semiconductor substrate 6 corresponding to a region below this region. 11 are formed. A light spot α is formed on the light receiving surface of the first signal reading photodetector 11 by the reflected light beam.

As shown in FIG. 4, the reflected light flux reflected by the semi-transmissive film 10 and further reflected by the top surface 2b of the prism 2 reaches the bottom surface 2c of the prism 2 again, as shown in FIG. As described later, an anti-reflection film or a dielectric multilayer film 14 is formed in order to promote the transmittance of the light beam, and an upper surface portion of the first semiconductor substrate 6 corresponding to a region below this region is provided with: Second and third signal reading photodetectors 12, 13 are formed. A light spot I is formed on the light receiving surface of the second signal readout photodetector 12 by a reflected light beam. A light spot J is formed on the light receiving surface of the third signal readout photodetector 13 by the reflected light beam.

Here, each signal readout photodetector 11,
In detail, as shown in FIG. 3, positions 12 and 13 are conjugate with the semiconductor laser chip 8 which is substantially a light emitting point (that is, the position reflected by the top surface 2 b of the prism 2 in the illustrated case, (A focal point of the reflected light beam).

In this case, since the prism 2 is made of a birefringent material, when a reflected light beam enters the prism 2, the reflected light beam becomes an ordinary light (o-ray) or an “ordinary extraordinary light. "And the extraordinary light (e-ray). The two reflected light beams reflected by the top surface 2b of the prism 2 reach the bottom surface 2c of the prism 2 while being separated. Therefore, the second and third signal-reading photodetectors 12, 13 are provided so as to receive these two reflected light beams, respectively.

Here, "ordinary extraordinary light" will be described. The biaxial crystals such as KTP, the refractive indices n _x of the three refractive index direction, n _y, in n _z, often are two back of the refractive index is close values. Therefore, for example, in KTP, than _{n x ≒ n y <n z} , n x ≒ n y
= N _o, it is considered that n _z = n _e, can be handled in the same manner as uniaxial crystal. In this case, since n _x ≠ n _y, components corresponding to the ordinary ray uniaxial crystal, slightly walk-off (Wa
Although the phenomenon of lk-Off) occurs, it is called "ordinary extraordinary light" because it is close to ordinary light.

The first signal reading photodetector 11
Since the first signal reading photodetector 11 is close to the inclined surface portion 2a, the reflected light beam incident on the light beam can be substantially processed as a single light beam because it is slightly separated into two groups of light beams. The first signal readout photodetector 11 receives both light beams of the two groups.

Here, the light beam reflected by the semi-transmissive film 10 is applied to the prism 2 on the top surface 2 b of the prism 2.
Is reflected on the basis of the difference between the refractive index of the birefringent material and the refractive index of the air outside. That is, if the birefringent material forming the prism 2 is made of a material having a high refractive index, the top surface 2a of the prism 2 can act as a total reflection. Therefore, when a material having a high refractive index is used as the birefringent material forming the prism 2, it is not necessary to provide a total reflection film on the upper surface of the prism 2 as in the related art. In the case of using the above material, as shown in FIG. 4, the high reflection layer 1 is formed on the upper surface of the prism 2 in order to prevent the light amount of the light beam from decreasing.
5 may be provided. The high reflection layer 15 is composed of, for example, a dielectric high reflection film having a reflectance of about 98%.
It may be composed of a metal film or a metal plate such as l or Ag.

Here, the prism 2 has the bottom surface 2c fixed to the first semiconductor substrate 6 by an adhesive. Generally, the refractive index of the adhesive is about 1.5 in the near infrared region of, for example, 780 nm. Therefore, when the refractive index difference between the birefringent material forming the prism 2 and the adhesive is large, it is desirable to provide the antireflection film 14 between the prism 2 and the layer of the adhesive.

Further, in the prism 2, the angle distribution of the characteristics of the polarizing beam splitter film 9, the semi-transmissive film 10, and the like, the distribution of the birefringent material constituting the prism 2 in the light beam in the intrinsic polarization direction of the crystal, and the like. In some cases, a light amount distribution occurs in the light beam of the incident reflected light beam. Such a light amount distribution may adversely affect not only a magneto-optical reproduction signal but also a servo signal in some cases. Therefore, in order to correct the light amount distribution described above, P
A dielectric multilayer film 14 having a difference in optical characteristics with respect to polarized light and S-polarized light may be provided on the bottom surface 2 c of the prism 2.

Regarding the reflected light beam traveling inside the prism 2, since the prism 2 is formed of a birefringent crystalline material, the extraordinary light component
A phenomenon called “walk-off” occurs. This walk-off is a phenomenon in which the wavefront normal direction (wavefront normal vector k) according to Snell's law does not match the light beam direction (light beam vector S) in which light energy travels. By this walk-off, prism 2
Is formed of LN (LiNbO ₃ ) which is a uniaxial crystal, spots α, I formed on the light receiving surfaces of the first and second signal reading photodetectors 11, 12 due to extraordinary light. Is formed at a position shifted in the same direction along the C-axis setting direction of the uniaxial crystal with respect to a position determined according to Snell's law. The spot α formed on the first signal readout photodetector is a spot where two groups of light beams overlap. It is the extraordinary light component of the spot α that moves by walk-off.
Walk-off does not occur for ordinary light, and the spot J formed on the light receiving surface of the third signal readout photodetector 13 by ordinary light and the ordinary light component of the spot α are obtained according to Snell's law. Formed in position. Therefore, the first and second signal reading photodetectors 11,
Reference numeral 12 is formed at a position where the center of the light receiving surface coincides with the center of each of the spots α and I.

The prism 2 is made of a biaxial crystal K
When formed of TP (KTiOPO ₄ ), this KTP has characteristics close to a positive uniaxial crystal.
First and third signal reading photodetectors 1 due to extraordinary light
The spots α and J formed on the light receiving surfaces 1 and 13 are formed at positions shifted in the same direction along the Nc axis setting direction of the biaxial crystal with respect to the position obtained according to Snell's law. You. For the spot α, only the component of the extraordinary light moves. The walk-off hardly occurs for the “ordinary extraordinary light”, and the spot I formed on the light receiving surface of the second signal reading photodetector 12 due to the “ordinary extraordinary light” and the spot α The “ordinary extraordinary light” component is formed at a position determined substantially according to Snell's law. Therefore, the first and third signal-reading photodetectors 11 and 13 respectively output the spots α and J
Is formed at a position where the center of the light receiving surface coincides with the center of.

Further, the prism 2 is made of a uniaxial crystal Y
In the case of VO ₄ , spots α and J formed on the light receiving surfaces of the first and third signal reading photodetectors 11 and 13 due to extraordinary light are located at positions determined according to Snell's law. Is formed at a position shifted in the same direction along the C-axis setting direction of the uniaxial crystal. For the spot α, only the component of the extraordinary light moves. Walk-off does not occur for ordinary light, and the spot I formed on the light receiving surface of the second signal readout photodetector 12 by ordinary light and the ordinary light component of the spot α are obtained according to Snell's law. Formed in position. Therefore,
The first and third signal-reading photodetectors 11, 13 are:
The light receiving surface is formed at a position where the center of the light receiving surface coincides with the center of each of the spots α and J.

In FIG. 2, the prism 2 has an inclined surface 2a extending from the bottom 2b to the bottom 2c. Therefore, as shown in FIG. 5, a part of the light beam from the semiconductor laser chip 8 is
In some cases, the light may pass through the polarization beam splitter film 9 formed as described above, and directly enter the first signal reading photodetector 11 as stray light. In this case, the detection signal of the first signal readout photodetector 11 changes due to the stray light. For this reason, as shown in FIG. 6, when the reflected light beam from the magneto-optical disk 101 is incident on the inclined surface portion 2a of the prism 2, an unnecessary lower portion 9b is chamfered, so that the aforementioned stray light The incidence on the signal readout photodetector 11 is eliminated.

Further, on the first semiconductor substrate 6, a light receiving portion serving as an optical output detector (not shown) is formed, which is located on the rear side of the prism 2 when viewed from the semiconductor laser chip 8. This optical output detector receives a light beam emitted from the semiconductor laser chip 8 and transmitted through the prism 2 and detects the light emission output of the semiconductor laser chip 8. The emission output of the semiconductor laser chip 8 is controlled to a constant output according to the detection output output from the optical output detector (so-called front auto power control (FAPC)).

Each of the signal readout photodetectors 11 described above,
Reference numerals 12 and 13 are divided in the radial direction of the magneto-optical disk 101, respectively. That is, as shown in FIGS. 7 and 8, the first signal reading photodetector 11
A pair of divided light receiving portions b, which form a central portion of the first signal-reading photodetector 11 via three parallel dividing lines,
c and four divided light receiving portions a, b, c, d of a pair of divided light receiving portions a, d located on both sides of the divided light receiving portions b, c.

The second signal reading photodetector 12
Via a pair of parallel dividing lines, a pair of divided light receiving portions y ₁ and y ₂ forming a central portion of the second signal reading photodetector 12, and these divided light receiving portions y ₁ and y ₂ four-division light receiving portion x ₁ of the pair of light receiving portions x _1, x ₂ located on both sides of,
It is divided into y ₁ , y ₂ and x ₂ .

Further, the third signal readout photodetector 1
Reference numeral 3 denotes a pair of divided light receiving portions z ₁ and z ₂ forming a central portion of the third signal readout photodetector 13 via three parallel dividing lines, and these divided light receiving portions z ₁ and z. _It is divided into four divided light receiving portions w ₁ , z ₁ , z ₂ , w ₂ of a pair of divided light receiving portions w ₁ , w ₂ located on both sides of ₂ .

Then, each of the divided light receiving sections a, b, c, d and x
₁ , y ₁ , y ₂ , x ₂ , w ₁ , z ₁ , z ₂ , w ₂ , detection signals Sa, Sb, Sc, Sd and Sx ₁ , Sx ₂ , Sy ₁ , S
Each of y ₂ , Sw ₁ , Sw ₂ , Sz ₁ , and Sz ₂ is subjected to current-voltage conversion by an amplifier (not shown), and then, for example, an arithmetic circuit (not shown) formed on the first semiconductor substrate 6 of the light emitting / receiving element 1. Alternatively, each of the divided light receiving sections a, b, c, d, x
The _{1, y 1, y 2,} x 2, w 1, z 1, z 2, w 2 and connected receiving-emitting device 1 of the external operation circuit, as follows, a magneto-optical reproduction signal MO · RF, pit reproduction signal (read signal when reproducing a so-called pit disk) P
IT / RF, focus error signal FCS and tracking error signal TRK are calculated.

Then, the first signal reading photodetector 1
Since the separation of the two groups of light beams in the reflected light beam incident on 1 is slight, it can be treated as one light beam. That is, as shown in FIG. 9, the light spot α formed by the reflected light beam on the light receiving surface of the first signal readout photodetector 11 is a light spot formed by ordinary light or “ordinary extraordinary light”. alpha ₁ and the light spot alpha ₂ formed by the extraordinary light are those formed by overlapping slightly offset. Both side portions of these light spots α ₁ , α _{2 have} regions β ₁ , β ₂ , β having strong intensity distribution due to the influence of diffraction generated on the recording track of the magneto-optical disk 101.
₃ and β ₄ (the tracking error signal, which will be described later, can be detected by the intensity balance of these regions β ₁ , β ₂ , β ₃ , and β ₄ ).

The magneto-optical reproduction signal MO · RF is given by: MO · RF = (Sx ₁ + Sx ₂ + Sy ₁ + Sy ₂ ) − (Sw
₁ + Sw ₂ + Sz ₁ + Sz ₂ ), and the pit reproduction signal PIT · RF is: PIT · RF = (Sa + Sb + Sc + Sd) + (Sx ₁
+ Sx ₂ + Sy ₁ + Sy ₂ ) + (Sw ₁ + Sw ₂ + Sz ₁ + S
z ₂ ).

The pit reproduction signal PIT / RF is
(Sa + Sb + Sc + Sd), (Sx ₁ + Sx ₂ + Sy ₁
+ Sy ₂ ) and (Sw ₁ + Sw ₂ + Sz ₁ + Sz ₂ ).

Then, the focus error signal FCS is
Detection signal from the signal readout photodetector 11,12,13 (Sa, Sb, Sc, Sd), (Sx 1, Sx 2, S
y _1, Sy ₂₎ and _{(Sw 1, Sw 2, Sz} 1, Sz 2) of the can be obtained based on at least one of the detection signal. The tracking error signal TRK includes detection signals (Sa, Sb, Sc, Sd), (Sx ₁ , Sx ₂ , Sy
₁ , Sy ₂ ) and (Sw ₁ , Sw ₂ , Sz ₁ , Sz ₂ ) can be obtained by calculating any one set of detection signals.

Regarding the detection of the tracking error signal TRK, the magneto-optical reproduction signal MO · R is detected due to the low light receiving sensitivity of the signal reading photodetectors 11, 12, and 13.
In a system in which it is difficult to maintain a CNR (Carrier-to-Noise-Ratio: so-called CN ratio) in the detection of F, only the light spot α received by the first signal readout photodetector 11 detects the tracking error signal TRK. , The CNR of the magneto-optical reproduction signal MO / RF can be secured. That is, TRK = (Sa + Sb)-(Sc + Sd)

In this case, the optical recording medium may be a magneto-optical disk or a so-called pit disk. If the magneto-optical disk 101 is a groove disk having wobbles, the wobble components Sa _w ,
Using Sd _w , (Sa−Sd) _w and coefficient K _w , TRK = [{(Sa + Sb) − (Sc + Sd)} / (S
a + Sb + Sc + Sd)] _{- K w (Sa w -Sd w} ) /
(Sa−Sd) By setting _w , the D of the tracking error signal TRK
C offset can be removed.

In a system in which there is a strict requirement for the remaining tracking error, the light spot I received by the second signal reading light detector 12 or the third signal reading light detector 13 receives light. Light spots J or these light spots I and J
Are used for detecting the tracking error signal TRK, good tracking control can be performed for both the groove disk and the pit disk. _{That, TRK = (Sx 2 + Sy} 2) - (Sx 1 + Sy 1) TRK = (Sw 1 + Sz 1) - (Sw 2 + Sz 2) TRK = {(Sx 2 + Sy 2) + (Sw 1 + Sz 1)} -
{(Sx ₁ + Sy ₁ ) + (Sw ₂ + Sz ₂ )}

As described above, one of the spots I and J is moved along the optical path under the influence of the walk-off. Therefore, by using the one of the spots I and J, which has a smaller influence of the walk-off, for detecting the tracking error signal TRK, it is possible to suppress the asymmetry with respect to the movement of the field of view of the objective lens 5 due to the influence of the walk-off. The visual field movement of the objective lens 5 is caused by a tracking servo operation described later).

Further, by using both the spots I and J for detecting the tracking error signal TRK, it is possible to reduce the influence on the tracking error signal TRK due to a change in the polarization component (a change in the light amount ratio of the two groups of light beams).

Further, in a system in which the defocus is large and is easily affected by the light spot diameter on the signal recording surface, the light spot α, I, the light spot α, J, or the light spot α, I , J are used for detecting the tracking error signal TRK, it is possible to reduce the influence of the change in the light spot diameter on the signal recording surface on the tracking error signal TRK. That is, TRK = {(Sa + Sb) + K1 (Sx ₂ + Sy ₂ )} −
{(Sc + Sd) + K1 (Sx 1 + Sy 1)} TRK = {(Sa + Sb) + K2 (Sw 1 + Sz 1)} -
{(Sc + Sd) + K2 (Sw 2 + Sz 2)} TRK = {(Sa + Sb) + K1 (Sx 2 + Sy 2) + K
2 (Sw ₁ + Sz ₁ )｝ − ｛(Sc + Sd) + K1 (Sx
_{1 + Sy 1) + K2 (} Sw 2 + Sz 2)}

Here, the constants K1 and K2 are determined by the semi-permeable membrane 10
Is determined based on the light amount ratio distributed by That is, the constants K1 and K2 are the intensity (Pα) of the reflected light beam received by the first signal-reading photodetector 11 and the second,
Alternatively, the ratio (P) to the intensity (PI, PJ) of the reflected light beam received by the third signal readout photodetectors 12, 13
α / PI) or (Pα / PJ). That is, K1 = Pα / PI = (Sb + Sc + Sa + Sd) / (S
_{y 1 + Sy 2 + Sx 1} + Sx 2) K2 = Pα / PJ = (Sb + Sc + Sa + Sd) / (S
z ₁ + Sz ₂ + Sw ₁ + Sw ₂ )

Further, in the detection of the tracking error signal TRK, only the light spot α, only the light spot I,
Only light spot J, light spots I and J, light spot α,
I, light spot α, J, or light spot α, I,
In any case where J is used,
(Top hold Push-Pull) method may be adopted. For example, TRK = ｛K · (Sa + Sb) _{Top hold−} (Sa + S
b)｝-｛K · (Sc + Sd) _{Top hold} − (Sc + S
d)｝

The focus error signal FCS is
Since the reflected light beam reflected twice in the prism 2 is separated into two groups of light beams, it can be obtained by the same calculation as in the case of the light receiving / emitting element 214 for “CD” shown in FIGS. I can't. Therefore, the focus error signal FC
S is calculated as follows.

Each signal reading photodetector 11, 12, 1
The shape of the spot formed by the reflected light beam on 3 changes depending on the shift between the focal position of the objective lens 5 and the signal recording surface of the magneto-optical disk 111. As described above, the separation of the reflected light beam incident on the first signal readout photodetector 11 into two groups of light beams is slight as shown in FIG. 9 and can be treated as one light beam. It is. Therefore, as shown in FIG. 8, each of the divided light receiving portions a, b, c, and d of the first signal readout photodetector 11 divided into four.
, And the detection signals Sx, from each of the divided light receiving portions x, y, w, z of one of the second and third signal reading photodetectors 12, 13. S
y, Sw, and Sz, the focus error signal F
CS is the following equation, where G is a positive constant: FCS = G ｛{(Sb + Sc) − (Sa + Sd)} −
{(Sy ₁ + Sy ₂ ) − (Sx ₁ + Sx ₂ )} or FCS = G · {(Sb + Sc) − (Sa + Sd)} −
{(Sz ₁ + Sz ₂ ) − (Sw ₁ + Sw ₂ )}.

Here, the constant G is determined based on the light amount ratio distributed by the semi-transmissive film 10. That is, the constant G is the intensity (Pα) of the reflected light beam received by the first signal readout photodetector 11 and the second or third signal readout photodetectors 12 and 13 receive light. The ratio (PI / Pα) to the intensity (PI, PJ) of the reflected light beam or (PJ / Pα). That is, G = PI / Pα = (Sy ₁ + Sy ₂ + Sx ₁ + Sx ₂ ) /
(Sb + Sc + Sa + Sd) or G = PJ / Pα = (Sz ₁ + Sz ₂ + Sw ₁ + Sw ₂ ) /
(Sb + Sc + Sa + Sd)

The focus error signal FCS is a signal indicating the distance between the focal point of the light beam emitted from the objective lens 5 and the signal recording surface in the optical axis direction of the objective lens 5. In the disc player device, the operation of moving the objective lens 5 in the direction of the optical axis of the objective lens 5, that is, the focus servo operation is performed as shown by an arrow F in FIG. 1 so that the focus error signal FCS becomes 0. Done. Further, the tracking error signal TRK is a signal representing the difference between the focal point of the light beam emitted from the objective lens 5 and the recording track.
This signal indicates a distance in a direction perpendicular to the tangent to the recording track and the optical axis of the objective lens 5, that is, in the radial direction of the magneto-optical disk 101. In the disc player device, as shown by an arrow T in FIG. 1, the objective lens 5 is moved in a direction tangential to the recording track and in a direction perpendicular to the optical axis of the objective lens 5 so that the tracking error signal TRK becomes zero. A moving operation, that is, a tracking servo operation is performed.

The disk player device according to the present invention includes a rotation operating mechanism for holding and rotating the magneto-optical disk 101, the above-described optical pickup device according to the present invention, the objective lens 5, and the objective lens 5. And an objective lens driving mechanism for supporting the lens and a control unit.

The rotary operation mechanism includes a spindle motor and a disk table attached to a drive shaft of the spindle motor. This disk table is configured to hold a central portion of the magneto-optical disk 101. The spindle motor rotates the magneto-optical disk 101 held by the disk table together with the disk table. In this disc player device, the optical pickup device is a magneto-optical disc 10 held on a disc table.
It is supported so as to face the first signal recording surface via the objective lens 5. The optical pickup device can be moved in the direction of approaching and separating from the spindle motor over the inner and outer circumferences of the magneto-optical disk 101.

The control means controls the light emission output of the semiconductor laser chip 8 based on the light detection output output from the light output detector of the optical pickup device. That is, in this disk player device, the light emission output of the semiconductor laser chip 8 is controlled based on the light detection output output from the light output detector, so that the signal is irradiated onto the signal recording surface of the magneto-optical disk 101. The amount of light flux is precisely controlled.

In this disc player apparatus, the focus servo operation and the tracking servo operation are performed by an objective lens driving mechanism (biaxial actuator) for supporting the objective lens 5 so as to be movable, as shown in FIG.
19 is performed. This objective lens driving mechanism 19
Has an actuator base 20. The actuator base 20 is formed in a substantially flat plate shape, and is disposed above the light emitting / receiving element 1. A support wall 21 is provided at one end of the actuator base 20. The support wall 21 has elastic support members 2
2 is fixed at its proximal end. This elastic support member 22
Is a member such as a leaf spring made of a metal material or a synthetic resin material, and is movable on the distal end side by elastic displacement. A lens holder 23 is attached to the distal end side of the elastic support member 22.

The lens holder 23 can be moved by the displacement of the elastic support member 22. The objective lens 5 is attached to the lens holder 23 with both surfaces facing outward. In a portion of the actuator base 20 facing the objective lens 5, a through hole 31 through which a light beam incident on the objective lens 5 passes is provided.

[0086] A focus coil 28 and a tracking coil 29 are mounted on the lens holder 23. On the actuator base 20, a pair of yokes 24, 25 to which magnets 26, 27 are attached are provided upright facing the focus coil 28 and the tracking coil 29. These magnets 2
6, 27 and yokes 24, 25
Are located in the generated magnetic field.

In the objective lens driving mechanism 19,
When a focus drive current is supplied to the focus coil 28, the focus coil 28
7, the lens holder 23 is moved in the optical axis direction of the objective lens 5, that is, in the focus direction, as indicated by an arrow F in FIG. The focus servo operation is performed by supplying the focus drive current based on the focus error signal FCS.
In the objective lens drive mechanism 19, when a tracking drive current is supplied to the tracking coil 29, the tracking coil 29
7, the lens holder 23 is moved in the direction perpendicular to the optical axis of the objective lens 5, that is, in the tracking direction, as indicated by an arrow T in FIG.
The tracking drive current is equal to the tracking error signal TRK.
, The tracking servo operation is performed. The tracking direction is set to the direction of the parallel divergence angle θ // in the semiconductor laser chip 8 in order to reduce the diameter of the beam spot formed by focusing the light beam on the magneto-optical disk 101 along the recording track. ing.

In the disk player apparatus according to the present invention, a hologram lens may be used as the light focusing means instead of the above-mentioned objective lens. In this case, the hologram lens can be manufactured so as to also have the functions of a beam splitter and a Wollaston prism, so that the prism 2 can be substituted by the hologram lens.

[0089]

As described above, in the optical pickup device according to the present invention, the light source, the first signal readout photodetector, the second signal readout photodetector, and the third signal readout are provided on the semiconductor substrate. A readout photodetector is provided, and a prism formed of a birefringent material is provided on the semiconductor substrate.

The prism emits a light beam reflected by the inclined surface portion of the prism and radiated onto the signal recording surface of the magneto-optical recording medium, the reflected light beam being a light beam reflected by the signal recording surface. The reflected light flux is returned to the surface portion, enters the prism through the inclined surface portion, is branched into two groups of light beams, and a part of these reflected light beams is transmitted through the bottom portion to the first signal reading light. The light flux reflected by the bottom surface portion of the reflected light beams is reflected by the top surface portion, and then guided to the second and third signal readout light detectors through the bottom surface portion.

In this optical pickup device, the light-receiving surface of the first signal-reading photodetector and / or the second and / or third signal-reading photodetector is divided into at least two parts. It is divided into light receiving sections, and a tracking error signal corresponding to the distance between the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium and the recording track is detected by the differential of the optical output signals from these divided light receiving sections. You.

That is, according to the present invention, the assembling process and the adjusting process can be facilitated, the size, the performance, and the durability can be reduced. It is possible to provide an optical pickup device capable of performing the following.

Further, according to the present invention, by providing the above-described optical pickup device, it is possible to provide a disk player device having good recording / reproducing characteristics for a magneto-optical recording medium.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of an optical pickup device according to the present invention, with a part thereof cut away.

FIG. 2 is a side view and a plan view of a light emitting and receiving element of the optical pickup device.

FIG. 3 is a side view showing a conjugate relationship between a light emitting point and a photodetector in the light receiving and emitting element.

FIG. 4 is a side view showing a configuration of a prism in the light receiving and emitting element.

FIG. 5 is a side view showing stray light in a prism in the light emitting and receiving element.

FIG. 6 is a side view showing stray light in a modification of the prism in the light emitting and receiving element.

FIG. 7 is a side view illustrating a configuration of the light emitting and receiving element.

FIG. 8 is a plan view showing a configuration of a photodetector of the light receiving and emitting element.

FIG. 9 is a plan view showing a shape of a light spot formed on a first signal reading photodetector in the light emitting and receiving element.

FIG. 10 is a longitudinal sectional view showing a configuration of an objective lens driving mechanism that supports an objective lens of the disc player device according to the present invention.

FIG. 11 is a side view showing a configuration of an optical system of a conventional optical pickup device.

FIG. 12 is a side view showing a configuration of a conventional optical pickup device using a light receiving / emitting element, with a part thereof cut away.

FIG. 13 is a side view showing a configuration of a light receiving / emitting element of the conventional optical pickup device.

FIG. 14 is a plan view showing a configuration of a light emitting / receiving element of the conventional optical pickup device.

FIG. 15 is a plan view showing the shape of a spot of a reflected light beam formed in the light receiving / emitting element of the conventional optical pickup device.

FIG. 16 is a plan view showing a shape of a spot of a reflected light beam formed when a visual field movement occurs in the light receiving / emitting element of the conventional optical pickup device.

FIG. 17 is a waveform chart for explaining a TPP method executed in the conventional optical pickup device.

FIG. 18 is a cross-sectional view of the conventional optical pickup device.
FIG. 3 is a block circuit diagram illustrating a configuration of an arithmetic circuit that executes a PP method.

FIG. 19 is an enlarged vertical sectional view showing a modification of the light emitting and receiving element shown in FIG.

[Explanation of symbols]

Reference Signs List 2 prism, 2a inclined surface portion, 2b top surface portion, 5 objective lens, 6 first semiconductor substrate, 8 semiconductor laser chip, 11 first signal reading photodetector, 12 second signal reading photodetector, 13 third signal reading photodetector, a, b, c, d , w 1, w 2, x 1, x 2,
y ₁ , y ₂ , z ₁ , z ₂ divided light receiving unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Sasaki 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Kenji Araki 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Kazuhiko Okamatsu 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (5)

[Claims] 1. A light source disposed on a semiconductor substrate, a first signal reading light detector, a second signal reading light detector, and a third signal reading light detector, and a birefringent material. Having a bottom surface portion and a top surface portion parallel to each other, one end portion is formed as an inclined surface portion inclined with respect to the bottom surface portion as a light beam branching surface, an optical axis when the birefringent material is a uniaxial crystal, Alternatively, among the three refractive index directions in the case where the birefringent material is a biaxial crystal, the direction corresponding to the refractive index having the larger difference from the intermediate refractive index is perpendicular to the normal line of the top surface and the bottom surface. Is set within a certain plane,
A prism bonded to an upper surface of the semiconductor substrate with the bottom surface positioned on each of the signal readout photodetectors and the inclined surface facing the light source, wherein the prism is emitted from the light source, and The light beam reflected by the inclined surface portion and applied to the recording track on the signal recording surface of the magneto-optical recording medium returns the reflected light beam, which is the light beam reflected on the signal recording surface, to the inclined surface portion. The light enters the prism through the inclined surface portion and is split into two groups of light beams. A part of the reflected light beams is guided to the first signal reading photodetector through the bottom surface portion, and the reflected light beams are reflected. The light beam reflected by the bottom surface portion of the light beam is reflected by the top surface portion, and then guided to the second and third signal readout photodetectors through the bottom surface portion. For reading 1 signal The light-receiving surface of the detector is divided into at least two divided light-receiving parts, and the difference between the light output signals from these divided light-receiving parts is used to determine the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium. An optical pickup device wherein a tracking error signal corresponding to the distance from the recording track is detected. 2. A light source disposed on a semiconductor substrate, a first signal reading light detector, a second signal reading light detector, and a third signal reading light detector, and a birefringent material. Having a bottom surface portion and a top surface portion parallel to each other, one end portion is formed as an inclined surface portion inclined with respect to the bottom surface portion as a light beam branching surface, an optical axis when the birefringent material is a uniaxial crystal, Alternatively, among the three refractive index directions in the case where the birefringent material is a biaxial crystal, the direction corresponding to the refractive index having the larger difference from the intermediate refractive index is perpendicular to the normal line of the top surface and the bottom surface. Is set within a certain plane,
A prism bonded to an upper surface of the semiconductor substrate with the bottom surface positioned on each of the signal readout photodetectors and the inclined surface facing the light source, wherein the prism is emitted from the light source, and The light beam reflected by the inclined surface portion and applied to the recording track on the signal recording surface of the magneto-optical recording medium returns the reflected light beam, which is the light beam reflected on the signal recording surface, to the inclined surface portion. The light enters the prism through the inclined surface portion and is split into two groups of light beams. A part of the reflected light beams is guided to the first signal reading photodetector through the bottom surface portion, and the reflected light beams are reflected. The light beam reflected by the bottom surface portion of the light beam is reflected by the top surface portion, and then guided to the second and third signal readout photodetectors through the bottom surface portion. 2 and / or third Receiving surface of the No. reading optical detector is divided into at least two light receiving portions, a differential of the optical output signal from the divided light receiving portions,
An optical pickup device wherein a tracking error signal corresponding to a distance between the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium and the recording track is detected. 3. The light-receiving surface of the first signal-reading photodetector is divided into at least two divided light-receiving portions, and the divided signal-receiving portion of the first signal-reading photodetector and the second light-receiving portion. 3. A tracking error signal is detected by a differential of an optical output signal from a divided light receiving portion of the signal reading photodetector and / or a divided light receiving portion of the third signal reading photodetector. An optical pickup device as described in the above. 4. A medium holding mechanism for holding a magneto-optical recording medium, a light source disposed on a semiconductor substrate, a first signal reading light detector, a second signal reading light detector, and a third signal reading light detector. A signal detection photodetector, an optical axis formed when the birefringent material is a uniaxial crystal having a bottom surface portion and a top surface portion which are formed of a birefringent material and which are parallel to each other, or the birefringent material is a biaxial crystal Of the three refractive index directions, the direction corresponding to the refractive index having a larger difference from the intermediate refractive index is set in a plane perpendicular to the normal line of the top and bottom surfaces, and one end is a light beam. An inclined surface portion inclined with respect to the bottom surface portion as a branch surface, the bottom surface portion is positioned on each of the signal readout photodetectors, and the inclined surface portion is bonded to the upper surface portion of the semiconductor substrate toward the light source; The light emitted from the light source is The light beam reflected and condensed on the signal recording surface of the magneto-optical recording medium by the light condensing means is returned to the inclined surface portion via the light condensing means, and the reflected light beam is a light beam reflected on the signal recording surface, This reflected light flux enters the prism through the inclined surface portion and is split into two groups of light beams, and a part of these reflected light beams is transmitted through the bottom surface portion to the first signal reading photodetector. A prism for guiding the light beam reflected by the bottom surface portion of the reflected light beams by the top surface portion, and then guiding the light beam to the second and third signal reading photodetectors through the bottom surface portion. An arithmetic circuit for performing an arithmetic operation based on a light detection output output from each of the signal readout photodetectors, wherein a light receiving surface of the first signal readout photodetector is provided in at least two divided light receiving portions. The operation circuit is divided Due to the differential of the optical output signal from these split photodetectors,
A disk player device for detecting a tracking error signal corresponding to a distance between the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium and the recording track. 5. A medium holding mechanism for holding a magneto-optical recording medium, a light source disposed on a semiconductor substrate, a first signal reading light detector, a second signal reading light detector, and a third signal reading light detector. A signal detection photodetector, an optical axis formed when the birefringent material is a uniaxial crystal having a bottom surface portion and a top surface portion which are formed of a birefringent material and which are parallel to each other, or the birefringent material is a biaxial crystal Of the three refractive index directions, the direction corresponding to the refractive index having a larger difference from the intermediate refractive index is set in a plane perpendicular to the normal line of the top and bottom surfaces, and one end is a light beam. An inclined surface portion inclined with respect to the bottom surface portion as a branch surface, the bottom surface portion is positioned on each of the signal readout photodetectors, and the inclined surface portion is bonded to the upper surface portion of the semiconductor substrate toward the light source; The light emitted from the light source is The light beam reflected and condensed on the signal recording surface of the magneto-optical recording medium by the light condensing means is returned to the inclined surface portion via the light condensing means, and the reflected light beam is a light beam reflected on the signal recording surface. This reflected light flux enters the prism through the inclined surface portion and is split into two groups of light beams, and a part of these reflected light beams is transmitted through the bottom surface portion to the first signal reading photodetector. A prism for guiding the light beam reflected by the bottom surface portion of the reflected light beams by the top surface portion, and then guiding the light beam to the second and third signal reading photodetectors through the bottom surface portion. An arithmetic circuit for performing an arithmetic operation based on a light detection output output from each of the signal readout photodetectors, wherein at least two light receiving surfaces of the second and / or third signal readout photodetectors are provided. Is divided into
The arithmetic circuit detects a tracking error signal corresponding to a distance between the irradiation position of the light beam on the signal recording surface of the magneto-optical recording medium and the recording track based on a difference between the optical output signals from the divided light receiving units. Disc player device.