JP3360324B2 - Optical head device and optical disk device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device suitable for use in an optical head of a magneto-optical disk device and an optical disk device provided with the optical head device.

[0002]

2. Description of the Related Art FIG. 6 shows an example of the configuration of a conventional magnetic field modulation type magneto-optical disk drive. As shown in FIG.
The light beam emitted from the semiconductor laser 60 is converted into parallel light by the collimator lens 65, and the light beam transmitted through the polarizing beam splitter 61 is reflected by the rising mirror 62 and is condensed on the magneto-optical disk 70 by the objective lens 63. Is done. Light emitted from the semiconductor laser 60 and reflected by the polarization beam splitter 61 is incident on a monitor 67 as a photodetector in order to detect the amount of light emitted from the semiconductor laser 60.

When information is recorded on the magneto-optical disk 70, a light beam is focused on the magneto-optical disk 70, and the information is recorded on the magneto-optical disk 70 in accordance with the information to be recorded (signal 0 or 1). Information is recorded by changing the polarity of the facing magnet 71. This is called a Curie point recording method, and is magnetized in a direction perpendicular to the magneto-optical disk 70.

When reproducing information recorded on the magneto-optical disk 70, the magneto-optical disk 7
When the light beam condensed at 0 is reflected, its polarization plane, that is, the vibration direction of the light is rotated right or left by θk in accordance with the magnetization direction of the magneto-optical disk 70. The recorded information is reproduced by detecting a change in the rotation angle of the polarization plane of the reflected light. That is, the reflected light from the magneto-optical disk 70 passes through the objective lens 63,
Reflected by the polarization beam splitter 61, the λ / 2 wavelength plate 6
4 , the polarization is rotated by 45 degrees, and the polarization beam prism 68 separates the polarization plane into the S-polarized light and the P-polarized light that include the rotation θk of the polarization plane generated by the Kerr effect as an inverse component. The separated S-polarized light and P-polarized light are incident on photodetectors 69a and 69b, and output signals from the photodetectors 69a and 69b are extracted to obtain an RF signal (MO signal). Focus error signals are respectively obtained by the concentric circle method.

[0005]

By the way, in such an apparatus, the optical components such as the semiconductor laser 60 and the collimator lens 65 must be individually arranged as is apparent from the drawing, and the objective lens 63 It is necessary to additionally provide the rising mirror 62 for following the above, and it is difficult to reduce the size.

When arranging each component, it is necessary to adjust the position of each component with high precision, so that there is a problem that assembling is not easy and time is required for manufacturing. In addition, each of the assembled components may change or its position may be shifted due to external factors such as temperature, humidity, and external vibration, so that the optical characteristics at the time of initial setting are easily affected by these external factors. And there was a problem with the reliability of the device.

Accordingly, an object of the present invention is to reduce the size of an optical head device to facilitate its manufacture and to improve the reliability.

[0008]

SUMMARY OF THE INVENTION The above object is achieved, according to the present invention, fixed to the substrate, a light emitting means for emitting light is irradiated to the reflection to a recording medium the light from said light emitting means, said an optical path branching means for transmitting the reflected light from the recording medium, the light
A surface on which the light from the road branching means is incident, and
At least a surface that reflects and transmits light, and is fixed to the substrate.
And the light path branching surface is incident on the light incident surface.
Means are joined, a polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S-polarized light, provided on the substrate
Is, reflection of the first and second comprises a light receiving means, the bonding surfaces before Symbol polarizing means and said optical path splitting means of the polarization means respectively receiving the reflected and the transmitted light by the polarization means
And the intersection line between the transmission surfaces, and a straight line connecting the spot center of the reflecting surface of the optical path splitting means by the light emitting point and the light emitting means of said light emitting means and characterized by having a predetermined inclination Is solved by an optical head device. According to the present invention, there is provided a light emitting unit fixed to a substrate and emitting light, and a surface reflecting and transmitting light from the light emitting unit.
Irradiating the recording medium with light reflected by the reflection and transmission surface, an optical path branching unit that transmits the reflected light from the recording medium, and a surface on which the light from the optical path branching unit is incident.
At least a surface that reflects and transmits incident light.
And is fixed to the substrate and receives the light.
Is joined to the optical path splitting means to the surface, and polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S polarized light,
First and second light receiving means for receiving reflected and the transmitted light respectively by the polarizing means is provided on the substrate,
A first reflecting means provided on the optical path branching means for reflecting light transmitted through the reflecting and transmitting surface of the light emitted from the light emitting means; and the first reflecting means provided on the substrate. And a third light receiving means for receiving the light reflected by the optical head device. According to the present invention, the above object is provided.
Fixed to the substrate, a light emitting means for emitting light is irradiated to the reflection to a recording medium the light from said light emitting means, an optical path branching means for transmitting the reflected light from the recording medium, the optical path branching
A surface on which light from the means is incident, and a surface for reflecting the incident light.
And at least a transmitting surface, and is fixed to the substrate.
The Rutotomo, said optical path splitting means to the surface to be incident the light
Are joined, and polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S-polarized light, it is provided on the substrate,
Comprising a first and second light receiving means for receiving reflected and the transmitted light respectively by the polarizing means, the reflection of the joint surface and the front Symbol polarizing means and said optical path splitting means of said polarizing means and magnetic <br/> and intersection line between the over-surfaces, and the line connecting the centers of the spots on the reflecting surface of the optical path splitting means by the light emitting point and the light emitting means of said light emitting means is characterized by comprising a predetermined slope Solved by the optical disk device.

[0009]

As shown in FIG. 1 and FIG.
Reflects the laser light from the light emitting means 4 to irradiate the recording medium 70 and transmits the reflected light from the recording medium 70. When the transmitted light enters the polarizing means 3, the polarizing means 3
The intersection (hereinafter referred to as the axis of the polarizing means) between the surface of the polarizing means 3 and the reflecting or transmitting surface of the polarizing means 3;
Since the light emitting point of the light emitting means 4 and the straight line connecting the center of the spot on the reflection surface of the light path branching means 2 by the light emitting means 4 have an inclination of about 45 degrees, the light reflected by the light path branching means 2 The polarization direction has an inclination of about 45 degrees with the axis of the polarization means. That is, the polarization direction of the light is incident on the polarization means 3 at an angle of about 45 degrees. In particular, when the recording medium is a magneto-optical disk, as shown in FIG. 3, since the polarization plane rotation .theta.k caused by the Kerr effect can be separated into P-polarized light and S-polarized light including the inverse components, the first light receiving means By taking the difference between the S-polarized light and the P-polarized light received by the second light receiving means 8 and the second light receiving means 7, the recorded magnetism can be suitably reproduced.

[0010] The laser beam from the light emitting means 4 is split into an optical path branching means.
2 , the light is reflected by the first reflecting means 109, and is received by the third light receiving means 10, so that the amount of light emitted from the laser light can be detected. In particular, it is possible to monitor the amount of emitted light when writing to a magneto-optical disk.

The first light receiving means 8 can be formed on the substrate 1 by reflecting the light reflected by the polarizing means 3 by the second reflecting means 110.

Since the optical path branching means 2 and the polarizing means 3 each have an inclination of about 45 degrees with respect to the substrate 1, P-polarized light and S-polarized light can be suitably separated, and the optical path of each reflected light can be adjusted. It can be controlled parallel or perpendicular to the substrate 1.

Further, according to the present invention, the differential amplifier 27 for processing the outputs of the first light receiving means 8 and the second light receiving means 7 is provided.
29 and 36 to 38, a focus error signal,
A tracking error signal or a reproduction signal from a magneto-optical disk can be detected.

[0014]

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

FIG. 1 is a perspective view showing the configuration of a magneto-optical disk drive according to an embodiment of the present invention. FIG. 2 is a diagram of FIG. 1 as viewed from each direction of A, B, and C. In particular, FIG.
2B is a diagram viewed from the A direction, FIG. 2B is a diagram viewed from the B direction, and FIG.

As shown in FIGS. 1 and 2, a semiconductor laser 4 is mounted on a semiconductor substrate 1, and a beam splitter 3 composed of a right-angled isosceles triangular prism and a parallelogram prism bonded at a surface 106 is provided. The semiconductor laser 4 is adhered on the semiconductor substrate 1 at an angle of 45 degrees with the mounting direction E. A beam splitter 2 composed of two right-angled isosceles triangular prisms bonded at a surface 105 is fixed on the beam splitter 3 in parallel with the mounting direction E of the semiconductor laser 4.

The surface 106 of the beam splitter 3 is a polarization separation film, and has a P-polarized light transmittance Tp = 100%, a P-polarized light reflectance Rp = 0%, an S-polarized light transmittance Ts = 0%, and an S-polarized light reflectance R
s = 100%, surface 1 of beam splitter 2
Reference numeral 05 denotes a polarization separation semi-transmissive film, Ts = 30%, Rs =
It is designed to have characteristics of 70%, Tp = 100%, and Rp = 0%. The surface 110 parallel to the surface 106 of the beam splitter 3 and the surface 109 of the beam splitter 2 are each coated with a reflection film. Semiconductor substrate 1
Inside, photodetectors 7a to 7c and 8 each of which is divided into three photodetectors 7 and 8 for reading a recording signal.
a to 8 c and the photodetector 10 are arranged at right angles to the mounting direction E of the semiconductor laser 4.

As shown in FIGS. 1 and 2, an S-polarized light beam emitted from the semiconductor laser 4 and having a polarization direction perpendicular to the mounting direction E is reflected by the light splitting polarization separation film 105, and The light is focused on the magneto-optical disk 70 by 15 and reflected by the Kerr effect of the magnetic domain recorded on the magneto-optical disk 70 while rotating the polarization plane by θk. Through the polarization splitting film 105.

As shown in FIG. 2A, the incident polarization direction of the light beam transmitted through the light splitting polarization splitting film 105 is parallel to E, and the beam splitter and the beam splitter 2
Since the light is inclined at an angle of 5 degrees, the light is incident on the surface 106 of the beam splitter 3 in a polarization direction inclined at 45 degrees. The P-polarized light component of the light beam incident on the polarization splitting film 106 is transmitted and received by the photodetector 7, and the S-polarized light component is reflected.
After being reflected by the reflection film 109, the light is received by the photodetector 8.

As shown in FIG. 3, the P-polarized light component and the S-polarized light component received by the photodetectors 7 and 8 respectively include the rotation θk of the polarization plane caused by the Kerr effect as an inverse component. By taking the differential outputs of (8) and (8), the magnetic domains recorded on the magneto-optical disk 70 can be detected.

In detecting the amount of the emitted light beam at the time of recording, a part of the light beam emitted from the semiconductor laser 4 is transmitted through the light splitting polarization separating film 105 and reflected by the reflecting film 109, and the trapezoidal beam splitter 3 This is made possible by detecting the amount of light transmitted and incident on the photodetector 10. At this time, face 1
By using a polarization separating film 09, it is also possible to remove a light amount detection error caused by a change in the polarization ratio (not completely S-polarized light) due to a temperature change.

FIG. 4 shows an RF signal (MO) according to the first embodiment.
FIG. 3 is a circuit configuration diagram for obtaining a focus error signal and a tracking error signal.

As shown in FIG. 4, the photodetectors 7 and 8 are divided into three photodetectors 7a, 7b, 7 respectively.
c, 8a, 8b, 8c, and the signals A, B, C, A ', B', C 'are output from the photodetectors 7a, 7b, 7c, 8a, 8b, 8c, respectively, and each terminal of these photodetectors is output. Are input to the adders 21 to 26.

First, since the RF signal is generated by the Kerr effect and includes the rotation of the plane of polarization as an inverse component, the RF signal can be obtained by taking the difference between the amounts of light detected by the photodetectors 7 and 8. That is, the photodetectors 7a, 7a of the photodetector 7
The sum of the light amounts of b and 7c is obtained by an adder 24, the sum of the light amounts of the photodetectors 8a, 8b and 8c of the photodetector 8 is obtained by an adder 23, and the outputs from the adders 23 and 24 are obtained. To the differential amplifier 28,
By taking the differential, the RF signal ((A + B + C)-
(A '+ B' + C ')) is obtained.

Further, in this embodiment, when the converging point of the converged light beam is located on the magneto-optical disk 70, the conjugate point of this converging point is located in the middle between the polarization separating film 106 and the reflecting film 109. It is arranged to be. Accordingly, the P-polarized spot on the photodetector 7 or the S-polarized spot on the photodetector 8 is equal to each other when the focal point is located on the magneto-optical disk 70, and when the focal point is not located on the magneto-optical disk 70. Becomes larger.
Therefore, the sum of the light amounts of the photodetectors 7a, 7c and 8b is calculated by the adder 21, and the sum of the light amounts of the photodetectors 8a, 8c and 7b is calculated by the adder 22 and supplied to the differential amplifier 27 to obtain the difference. Focus error signal ((A + CB)-(A '+ C'-B'))
Is obtained.

The tracking error signal is obtained by taking the sum of the difference between the light amounts of the photodetectors 7a and 7c sandwiching the photodetector 7b and the photodetector 8b in the track direction and the difference between the light amounts of the photodetectors 8a and 8c. Obtained by the pull method. That is, the photodetectors 7a,
The sum of the light amounts with the photodetectors 8a and 7c is obtained by an adder 25, and the sum of the light amounts with the photodetectors 8a and 7c is supplied to a differential amplifier 29. -C) + (C'-A ')).

Although the present embodiment is applied to the case of a magneto-optical disk device, the present invention can also be applied to a compact disk, and the phase pit detection signal (reproduction signal) on the compact disk is a photodetector 7a,
7b, 7c, 8a, 8b, 8c ((A +
B + C) + (A '+ B' + C ')).

FIG. 5 is a circuit diagram for obtaining an RF signal (MO signal), a focus error signal, and a tracking error signal according to a second embodiment of the present invention.

As shown in FIG. 5, photodetectors 7 and 8 are separated by photodetectors 7d to 7g and 8d to 8g.
Has been split. The photodetectors 7d to 7g and 8d to 8d are D, E, F, G and D ', E',
Signals of F 'and G' are output. The terminals of the photo detectors 7d to 7g and 8d to 8g are adders 30 to 35.
, And adders 30 to 35 are provided with differential amplifiers 36 to 38.
It is connected to the. The RF difference signal is ((D + E + F + G)-
(D ′ + E ′ + F ′ + G ′)), and the tracking error signal is obtained by the push-pull method ｛((D + E) − (F +
G)) + ((F ′ + G ′)) − (D ′ + E ′))}, and the focus error signal is obtained by the differential concentric circle method {((D +
G)-(E + F)) + ((D '+ G'))-((E '+
F '))｝.

[0030]

As described above, according to the present invention, since the semiconductor laser, the two beam splitters, and the photodetector can be integrally formed on the substrate, the size of the apparatus can be reduced. Since the displacement between the components is reduced, the reliability of the optical head device can be improved. In addition, the number of steps for adjusting each component can be reduced. Further, the signal processing circuit can be integrated on the substrate.

[Brief description of the drawings]

FIG. 1 is a perspective view of a magneto-optical disk device according to an embodiment.

FIG. 2 is a diagram viewed from each of A, B, and C directions in FIG. 1;

FIG. 3 is a diagram for explaining an MO reproduction signal.

FIG. 4 is a circuit configuration diagram for obtaining an MO signal, a focus error signal, and a tracking error signal according to the first embodiment.

FIG. 5 is a circuit configuration diagram for obtaining an MO signal, a focus error signal, and a tracking error signal according to a second embodiment.

FIG. 6 is a configuration diagram of a magneto-optical disk device according to a conventional example.

[Explanation of symbols]

 Reference Signs List 1 semiconductor substrate (substrate) 2 beam splitter 3 beam splitter 4 semiconductor laser (light emitting means) 7 photodetector (second light receiving means) 8 photodetector (first light receiving means) 10 photodetector (third light receiving means) 15 Objective lenses 7a to 7g, 8a to 8g Photodetectors 21 to 26, 30 to 35 Adders 27 to 29, 36 to 38 Differential amplifiers 60 Semiconductor lasers 61 Polarization beam splitters 62 Start-up mirrors 63 Objective lenses 64 λ / 2 wavelength plates 67 Monitor (PD) 68 Polarized beam prism 69a, 69b Photodetector 70 Magneto-optical disk 71 Magnet

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 11/105 G11B ^7/ 12-7/22

Claims (20)

(57) [Claims] 1. A fixed to the substrate, a light emitting means for emitting light, an optical path branching means for reflecting the light irradiating the recording medium, transmits the reflected light from the recording medium from said light emitting means, A surface on which light from the optical path branching means is incident, and
At least a surface that reflects and transmits the reflected light.
The light is fixed to a plate and the light
Road branching means is joined, and polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S-polarized light, is provided on the substrate, was umbrella reflected and magnetic <br/> by the polarization means comprising a first and second light receiving means for receiving light, respectively, and the line of intersection of the reflection and transmission surfaces of the joint surface and the front Symbol polarizing means and said optical path splitting means of said polarizing means, light emission of the light emitting means An optical head device, wherein a point and a straight line connecting the center of a spot on the reflection surface of the optical path branching means by the light emitting means have a predetermined inclination. Wherein the intersection line between reflection and transmission surfaces of the joint surface and the front Symbol polarizing means and said optical path splitting means of the polarization means,
The light emitting point of the light emitting means and the light path branching by the light emitting means
2. The optical head device according to claim 1, wherein a straight line connecting the centers of the spots on the reflecting surface of the means has an inclination of about 45 degrees. 3. The light path branching means includes a surface for reflecting and transmitting light from the light emitting means ,
Of the light emitted from the means,
The apparatus according to claim 1 , further comprising a first reflection unit configured to reflect the transmitted light, and a third light reception unit configured to receive the light reflected by the first reflection unit on the substrate. 2. The optical head device according to 1. 4. The polarizing means transmits and reflects the light.
Claim comprising a second reflecting means for reflecting the light reflected by the surface, the light reflected by said second reflecting means wherein the first light receiving means, characterized by comprising adapted to receive 1 Or the optical head device according to 2 or 3. 5. The optical head device according to claim 1, wherein the surfaces of the optical path branching means and the polarizing means, which reflect and transmit, have an inclination of about 45 degrees with respect to the substrate surface . 6. The first reflection means and the second reflection means,
5. The optical head device according to claim 3, wherein the optical head device has an inclination of about 45 degrees with the substrate surface . 7. The apparatus according to claim 1, further comprising signal processing means formed on said substrate, for processing the output of said first or second light receiving means.
7. The optical head device according to 4, 5, or 6. 8. The apparatus according to claim 1, wherein the signal processing unit outputs a focus error signal from an output of the first and / or second light receiving unit.
The optical head device according to claim 7, wherein a tracking error signal or a reproduction signal from the recording medium is detected. 9. A light emitting means fixed to a substrate and emitting light, and a surface for reflecting and transmitting light from the light emitting means.
Irradiating the recording medium with light reflected by the reflection and transmission surface, an optical path branching unit that transmits reflected light from the recording medium, a surface on which light from the optical path branching unit is incident, and
At least a surface that reflects and transmits the reflected light.
The light is fixed to a plate and the light
Road branching means are joined, the receiving and polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S-polarized light, reflected by said polarizing means is provided on the substrate and the transmitted light respectively and first and second light receiving means, disposed in said optical path splitting means, the first reflecting means for reflecting light transmitted through the reflection and transmission surfaces among the light emitted from the light emitting means, said substrate And a third light receiving means for receiving light reflected by the first reflecting means. 10. A line of intersection between the joint surface and the reflection and transmission surfaces before Symbol polarizing means and said optical path splitting means of said polarizing means, said optical path branching means by the light emission point and the light emitting means of said light emitting means 10. The optical head device according to claim 9, wherein a straight line connecting the centers of the spots on the reflecting surface has an inclination of about 45 degrees. 11. The polarizing means includes means for reflecting and transmitting light .
A second reflecting means for reflecting the light reflected by the first surface, wherein the first light receiving means receives the light reflected by the second reflecting means. 10. The optical head device according to 9. 12. The optical head device according to claim 9, wherein the reflection and transmission surfaces of the optical path branching unit and the polarizing unit have an inclination of about 45 degrees with respect to the substrate surface . 13. The optical head device according to claim 11, wherein the first reflection means and the second reflection means have an inclination of about 45 degrees with respect to the substrate surface . 14. The optical head according to claim 9, further comprising a signal processing unit formed on the substrate, the signal processing unit performing signal processing on an output of the first, second, or third light receiving unit. apparatus. 15. A focus error signal, a tracking error signal, or a reproduction signal from the recording medium is detected from an output of the first and / or second light receiving means, and the light emission means emits light from the third light receiving means. 10. The optical head device according to claim 9, wherein a light amount is detected. 16. is fixed to the substrate, a light emitting means for emitting light is irradiated to the reflection to a recording medium the light from said light emitting means, an optical path branching means for transmitting the reflected light from the recording medium, wherein A surface on which light from the optical path branching means is incident;
At least a surface that reflects and transmits the reflected light.
The light is fixed to a plate and the light
Road branching means is joined, and polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S-polarized light, is provided on the substrate, was umbrella reflected and magnetic <br/> by the polarization means comprising a first and second light receiving means for receiving light, respectively, and the line of intersection of the reflection and transmission surfaces of the joint surface and the front Symbol polarizing means and said optical path splitting means of said polarizing means, light emission of the light emitting means An optical disc device, characterized in that a point and a straight line connecting the center of a spot on the reflection surface of the light path branching means by the light emitting means have a predetermined inclination. 17. A line of intersection between the joint surface and the reflection and transmission surfaces before Symbol polarizing means and said optical path splitting means of said polarizing means, said optical path branching means by the light emission point and the light emitting means of said light emitting means 17. The optical disk device according to claim 16, wherein a straight line connecting the centers of the spots on the reflecting surface has an inclination of about 45 degrees. 18. A light-emitting device fixed to a substrate, the light-emitting device emitting light, and a surface for reflecting and transmitting light from the light-emitting device.
The recording medium is illuminated with light reflected by the reflective and transmissive surface, an optical path branching unit that transmits the reflected light from the recording medium, and a surface on which the light from the optical path branching unit is incident, and
At least a surface that reflects and transmits the reflected light.
The light is fixed to a plate and the light
Road branching means are joined, the receiving and polarizing means for optical path branching the light transmitted through the optical path splitting means to the P polarized light and S-polarized light, reflected by said polarizing means is provided on the substrate and the transmitted light respectively and first and second light receiving means, disposed in said optical path splitting means, the first reflecting means for reflecting light transmitted through the reflection and transmission surfaces among the light emitted from the light emitting means, said substrate An optical disk device, comprising: a third light receiving unit provided on the upper surface for receiving light reflected by the first reflecting unit. 19. A line of intersection between the joint surface and the reflection and transmission surfaces before Symbol polarizing means and said optical path splitting means of said polarizing means, said optical path branching means by the light emission point and the light emitting means of said light emitting means 19. The optical disk apparatus according to claim 18, wherein a straight line connecting the centers of the spots on the reflecting surface has an inclination of about 45 degrees. 20. A focus error signal, a tracking error signal, or a reproduction signal from the recording medium is detected from the output of the first and / or second light receiving means, and the light emitted from the light emitting means is emitted from the third light receiving means. 19. The optical disk device according to claim 18, wherein the light amount is detected.