JP4425485B2 - Optical pickup head and information recording / reproducing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup head and an information recording / reproducing apparatus.
[0002]
[Prior art]
Optical memory technology using an optical disk having a pit-like pattern as a high-density and large-capacity storage medium has been put into practical use. This optical memory technology is used as a digital audio disk, a video disk, and a data file disk. In recent years, a digital versatile disc (DVD) that has begun to spread is a high-density optical disc using a semiconductor laser having a wavelength of 650 nm as a light source. In the DVD, various media such as a read-only DVD-ROM, a DVD-R that can be recorded only once, and a DVD-RAM that can be recorded many times are standardized.
[0003]
Various types of optical pickup heads for recording and / or reproducing information on such optical discs have been reported. As an example of a conventional optical pickup head, a configuration of an integrated optical pickup head 100 disclosed in Japanese Patent No. 26759777 is schematically shown in FIG. 8 (hatching is omitted).
[0004]
With reference to FIG. 8, the optical pickup head 100 includes a semiconductor substrate 101 and a laser diode 102. A photodiode 103 is formed on the semiconductor substrate 101.
[0005]
The semiconductor substrate 101 is n-type and has a recess. The laser diode 102 is a single mode oscillation laser. The laser diode 102 is mounted in the recess of the semiconductor substrate 101 via the insulating layer 104. The photodiode 103 is formed on the side surface of the recess and outputs a current depending on the output of the laser diode 102. The current from the photodiode 103 is converted into a voltage signal by the resistor 105, and the voltage signal is output from the terminal 106. This voltage signal is input from the terminal 106 to the power control circuit. The power control circuit controls the operating current flowing through the laser diode 102 so that the output of the laser diode 102 becomes a desired value. A voltage of +5 V is applied from the terminal 107 to the semiconductor substrate 101 in order to apply a reverse bias voltage to the photodiode 103. A terminal 108 is connected to the side of the laser diode 102 in contact with the insulating layer 104, and a terminal 109 is connected to the opposite side. A high-frequency signal of several hundred MHz is applied to the terminal 109 from the npn transistor 110 in order to modulate the output of the laser diode 102. In the optical pickup head 100, by modulating the output of the laser diode 102, the laser beam reflected by the optical storage medium is prevented from entering the laser diode 102 and changing the output of the laser diode 102.
[0006]
The optical pickup head 100 includes a light receiving element that detects a laser beam reflected by the optical storage medium. By forming such a light receiving element on the semiconductor substrate 101, the optical pickup head can be reduced in size and can be easily manufactured.
[0007]
[Problems to be solved by the invention]
However, when the light receiving element is formed on the semiconductor substrate 101, there is a problem in that the light receiving element is affected by a high frequency signal and an offset occurs in the focus error signal and the tracking error signal. This is because the high frequency signal applied to the laser diode 102 is also applied to the semiconductor substrate 101 via the insulating layer 104.
[0008]
In order to solve the above problems, the present invention provides an optical pickup head that applies a high-frequency signal to a semiconductor laser, an optical pickup head in which an offset is hardly generated in a focus error signal and a tracking error signal, and an information recording / reproducing apparatus using the same. The purpose is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an optical pickup head of the present invention includes a semiconductor substrate and the semiconductor substrate. Through the insulating layer A mounted semiconductor laser; a light receiving element that receives a laser beam emitted from the semiconductor laser and reflected by an optical storage medium; and outputs a current signal corresponding to the amount of the received laser beam; and And a current-voltage conversion circuit that converts the signal, In the semiconductor laser, when the surface close to the insulating layer is the first surface, The semiconductor laser includes the laser beam reflected by the optical storage medium. Is incident on the semiconductor laser By Of the semiconductor laser A high-frequency signal to prevent the output from fluctuating From the first surface The light receiving element and the current-voltage conversion circuit are input on the semiconductor substrate. Monolithically Is formed. In the above optical pickup head, since the light receiving element that receives the laser beam reflected by the optical storage medium is formed on the semiconductor substrate on which the semiconductor laser is mounted, an optical pickup head with little change in characteristics over time can be obtained. It is done. In the optical pickup head, since the high frequency is applied to the semiconductor laser, the output of the semiconductor laser is stable. In the optical pickup head, since the light receiving element and the current-voltage conversion circuit are formed on the semiconductor substrate on which the semiconductor laser is mounted, the optical pickup head is hardly affected by a high-frequency signal input to the semiconductor laser. For this reason, an optical pickup head in which an offset hardly occurs in the focus error signal and the tracking error signal can be obtained.
[0010]
In the optical pickup head, the semiconductor substrate may be p-type. According to the above configuration, since the semiconductor substrate can be grounded, the potential of the semiconductor substrate can be stabilized and the influence of the high frequency signal can be particularly reduced.
[0011]
In the optical pickup head, the semiconductor laser includes a substrate and an active layer formed above the substrate, and the active layer is closer to the semiconductor substrate than the substrate. May be implemented. According to the above configuration, since heat generated by the semiconductor laser is quickly radiated to the semiconductor substrate, an optical pickup with particularly high reliability can be obtained.
[0012]
In the optical pickup head, the frequency f1 at which the gain of the current-voltage conversion circuit is −3 dB and the frequency f2 of the high-frequency signal may satisfy a relationship of f2 / f1 ≦ 5. According to the above configuration, it is possible to obtain an optical pickup head that can reproduce information at a high speed and has little unnecessary radiation.
[0013]
An information recording / reproducing apparatus of the present invention is an information recording / reproducing apparatus for reproducing information at least with respect to an optical storage medium, the optical pickup head of the present invention, the optical storage medium, and the optical pickup head. And a signal processing circuit for obtaining information recorded on the optical storage medium using a signal output from the optical pickup head. In the information recording / reproducing apparatus, since the optical pickup head of the present invention is used, an offset does not occur in the signal output from the current-voltage conversion circuit, so that a highly reliable information recording / reproducing apparatus can be realized.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings (hatching is omitted). The following embodiment is an example of the present invention, and the present invention is not limited to the following embodiment.
[0015]
(Embodiment 1)
In the first embodiment, an example of the optical pickup of the present invention will be described. The configuration of the optical pickup head 10 of Embodiment 1 is schematically shown in FIG. A top view of the semiconductor substrate 11 is schematically shown in FIG.
[0016]
The optical pickup head 10 includes a semiconductor substrate 11, a semiconductor laser 12 mounted on the semiconductor substrate 11, a first light receiving element 13, a second light receiving element 14 and a current-voltage conversion circuit 15 formed on the semiconductor substrate 11. And an optical system 16. The optical system 16 includes a hologram element 17, a collimating lens 18, an objective lens 19, and an aperture 20. Furthermore, the optical pickup head 10 includes actuators 21a and 21b for driving the objective lens 19 (hereinafter, both may be collectively referred to as actuator 21).
[0017]
The semiconductor substrate 11 is a p-type silicon substrate. The semiconductor substrate 11 is disposed in the package 22. A recess 11 a is formed in the semiconductor substrate 11. FIG. 3 shows an enlarged view of the recess 11a. The side surface of the recess 11a is an inclined surface that extends toward the opening. A reflection surface 11b for reflecting the laser beam is formed on a part of the side surface of the recess 11a. The reflective surface 11b can be formed by anisotropic etching. A second light receiving element 14 is formed on the side surface facing the reflecting surface 11b.
[0018]
The semiconductor laser 12 is a single-mode oscillation semiconductor laser. Specifically, a laser using an active layer made of GaInP and a clad layer made of p-type AlGaInP can be used. As shown in FIG. 3, the semiconductor laser 12 includes an n-type GaAs substrate 12a and a semiconductor layer 12b formed on the GaAs substrate 12a. The semiconductor layer 12b includes an active layer. An insulating layer 32 is formed on the recess 11 a of the semiconductor substrate 11. The semiconductor laser 12 is mounted on the electrode 33 formed on the insulating layer 32. At this time, the semiconductor laser 12 is mounted on the semiconductor substrate 11 via the insulating layer 32 so that the anode (the surface of the semiconductor layer 12b) is on the semiconductor substrate 11 side. That is, the semiconductor laser 12 is mounted on the semiconductor substrate 11 such that the active layer is closer to the semiconductor substrate 11 than the GaAs substrate 12a. Thus, by mounting the semiconductor laser 12 so that the surface close to the active layer of the semiconductor laser 12 is on the semiconductor substrate 11 side, the heat conduction between the active layer and the semiconductor substrate 11 can be improved. As shown in FIG. 6, the cathode (GaAs substrate 12a) of the semiconductor laser 12 is grounded.
[0019]
A high frequency signal HF (high frequency current) is superimposed and applied to the semiconductor laser 12 together with a driving signal (current). The high frequency signal HF is applied to prevent the laser beam reflected by the optical storage medium 40 from returning to the semiconductor laser 12 and changing the output of the semiconductor laser 12.
[0020]
As shown in FIG. 3, the semiconductor laser 12 emits linearly polarized divergent laser beams 30 and 31. The wavelengths of the laser beams 30 and 31 are, for example, 650 nm. The laser beam 30 is reflected by the reflecting surface 11b. The laser beam 31 is incident on the second light receiving element 14 formed on the slope of the recess 11a.
[0021]
As shown in FIG. 2, the first light receiving element 13 includes four light receiving elements 13a to 13d. The light receiving elements 13 a to 13 d and the second light receiving element 14 are photodiodes, each including a pn junction formed by implanting impurities into the semiconductor substrate 11. The first light receiving element 13 receives the laser beam 30 (diffracted lights 30a to 30c) reflected by the optical storage medium 40 and branched by the hologram element 17, and the light quantity of the received laser beam 30 (diffracted lights 30a to 30c). A current signal according to the output is output. The second light receiving element 14 directly receives the laser beam 31 emitted from the semiconductor laser 12 and outputs a current signal corresponding to the light amount of the laser beam 31.
[0022]
As shown in FIG. 2, the current-voltage conversion circuit 15 includes four current-voltage conversion circuits 15 a to 15 d formed monolithically on the semiconductor substrate 11. Each of the current-voltage conversion circuits 15a to 15d is connected to the light receiving elements 13a to 13d by a wiring 23, respectively. The wiring 23 is made of aluminum, for example. The current-voltage conversion circuits 15a to 15d output voltage signals corresponding to the current signals output from the light receiving elements 13a to 13d. As the current-voltage conversion circuits 15a to 15d, a general circuit such as a circuit disclosed in JP-A-8-45098 can be used. An example of the current-voltage conversion circuit 15a is shown in FIG. The current-voltage conversion circuit 15a in FIG. 5 can also be applied to the current-voltage conversion circuits 15b to 15d. The current-voltage conversion circuit 15 a in FIG. 5 includes an operational amplifier 51, a resistor 52, and a capacitor 53. Such a current-voltage circuit can be manufactured by a normal semiconductor process.
[0023]
The hologram element 17 transmits the laser beam 30 emitted from the semiconductor laser 12. Further, the hologram element 17 branches the laser beam 30 reflected by the optical storage medium 40. Instead of the hologram element 17, other branching means (branch element) may be used for the laser beam 30. As the collimating lens 18, for example, a lens having a focal length of 20 mm can be used. As the objective lens 19, for example, a lens having a focal length of 3 mm can be used. The aperture of the objective lens 19 is limited by the aperture 20, and its numerical aperture NA is, for example, 0.6.
[0024]
The laser beam 30 emitted from the semiconductor laser 12 is reflected by the reflecting surface 11 b and transmitted through the hologram element 17, and then converted into parallel light by the collimating lens 18. The laser beam 30 converted into parallel light is condensed by the objective lens 19, passes through the transparent substrate 40 a of the optical storage medium 40, and is condensed on the information recording surface 40 b. The thickness of the transparent substrate 40a is, for example, 0.6 mm.
[0025]
The laser beam 30 reflected by the information recording surface 40b passes through the objective lens 19 and the collimating lens 18, and then is branched into diffracted lights 30a to 30c by the hologram element 17. As shown in FIG. 4, the hologram element 17 has three regions 17a to 17c (shown by hatching), receives the beam 30, and receives the diffracted light 30a from the region 17a, the diffracted light 30b from the region 17b, and the region 17c. Diffracted light 30c is generated from The axis 17d is parallel to the boundary line between the region 17b and the region 17c, and the hologram element 17 is arranged so that the axis 17d is parallel to the mapping of the information recording surface 40b in the laser beam 30.
[0026]
The diffracted lights 30a to 30c are received by the light receiving elements 13a to 13d. Specifically, the light receiving elements 13a and 13b receive the diffracted light 30a, the light receiving element 13c receives the diffracted light 30b, and the light receiving element 13d receives the diffracted light 30c. And the light receiving elements 13a-13d output the current signal according to the received light quantity.
[0027]
The current signals output from the light receiving elements 13a to 13d are input to the current / voltage conversion circuits 15a to 15d via the wiring 23, respectively. The current-voltage conversion circuits 15a to 15d output a voltage signal corresponding to the input current signal to the outside.
[0028]
The focus error signal of the laser beam 30 is obtained by a well-known Foucault method. That is, the focus error signal is obtained by calculating the signals output from the light receiving elements 13a and 13b. The tracking error signal is obtained by the phase difference method when the medium is a DVD-ROM, and is obtained by the push-pull method when the medium is a DVD-RAM. Specifically, the tracking error signal is obtained by calculating signals output from the light receiving elements 13c and 13d. Although only half of the far-field laser beam 30, that is, the diffracted beams 30 b and 30 c are used to detect the tracking error signal, the tracking error signal can be obtained in the same manner as when the far-field pattern is used on the entire surface. .
[0029]
FIG. 6 shows the relationship between the high-frequency signal HF superimposed on the semiconductor laser 12 and the semiconductor substrate 11.
[0030]
The current signal output from the second light receiving element 14 is input to the output control circuit 61 that controls the output of the semiconductor laser 12. The drive signal output from the output control circuit 61 is input to the base of the laser driving transistor 62, whereby the operating current of the semiconductor laser 12 is controlled. A voltage of +5 V is applied to the terminal 63. A resistor 64 for protecting against overcurrent is connected between the transistor 62 and the terminal 63. The inductor 65 connected to the transistor 62 is a filter for preventing electromagnetic interference caused by the high frequency signal HF. Although only the inductor 65 is shown in FIG. 6, a low-pass filter using both an inductor and a capacitor may be used.
[0031]
The high frequency signal HF is AC-coupled from the oscillator 66 via the coupling capacitor 67 and supplied to the semiconductor laser 12. The frequency of the signal output from the oscillator 66 is, for example, in the range of 300 MHz to 600 MHz, for example, 500 MHz. The high frequency signal HF is applied to the semiconductor laser 12 through the electrode 33. Here, the electrode 33 and the semiconductor substrate 11 are opposed to each other with the insulating layer 32 interposed therebetween, and the electrode 33 and the semiconductor substrate 11 are usually coupled with a capacitance of several pF to several tens of pF. Therefore, the high-frequency signal HF is input not only to the semiconductor laser 12 but also to the first light receiving element 13, the wiring 23, and the current-voltage conversion circuit 15 through the semiconductor substrate 11.
[0032]
The first light receiving element 13 and the second light receiving element 14 are each composed of a pn junction including a p-type semiconductor substrate 11 and an n-type region formed in the semiconductor substrate 11. Since the semiconductor substrate 11 is p-type, the semiconductor substrate 11 is grounded as in a general integrated circuit. A voltage of +5 V (reference is the ground potential) is applied from the terminal 68 to the current-voltage conversion circuit 15, and a voltage of +2.5 V (reference is the ground potential) is applied from the terminal 69 as the reference voltage.
[0033]
In the optical pickup head 10, the high-frequency signal HF input to the semiconductor laser 12 passes from the electrode 33 to the current-voltage conversion circuit 15 via the insulating layer 32 and the semiconductor substrate 11 through the first light receiving element 13 and the wiring 23. Entered. However, in the optical pickup head 10, the same voltage is also applied to the grounded side 15 g of the current-voltage conversion circuit 15, so that the high-frequency signal HF is canceled in the current-voltage conversion circuit 15. Therefore, an offset is hardly generated in the signal output from the current-voltage conversion circuit 15, and an information recording / reproducing apparatus with high reliability can be realized. In particular, the offset can be reduced as the distance between the first light receiving element 13 and the current-voltage conversion circuit 15 is shorter. This distance is preferably 10 mm or less. On the other hand, when the current-voltage conversion circuit 15 is not formed on the semiconductor substrate 11, the mixing level of the high-frequency signal HF differs between the first light receiving element 13 and the current-voltage conversion circuit 15, and the signal offset is large. turn into.
[0034]
By using the optical pickup head 10, unlike the inventions disclosed in Japanese Patent Laid-Open Nos. 8-45098 and 7-287857, it is necessary to provide band limiting means between the light receiving element and the current-voltage conversion circuit. There is no. Further, unlike the invention disclosed in Japanese Patent Laid-Open No. 6-290475, it is possible to prevent the focus error signal and the tracking error signal from being offset without providing a shielding means for high frequency signals. Further, since the output of the semiconductor laser 12 is stabilized by using the optical pickup head 10, the information recording / reproducing apparatus using the optical pickup head 10 can faithfully read information recorded on the optical storage medium.
[0035]
In the optical pickup head 10, a semiconductor laser 12 having a semiconductor layer 12b formed on an n-type GaAs substrate 12a is used, and the cathode side is grounded. Since such a method of use is general, a widely used laser drive circuit or high-frequency oscillation circuit can be used, and the optical pickup head 10 can be manufactured at low cost. Even when a switching power supply is used to generate + 5V, the cathode of the semiconductor laser 12 is grounded, and since the transistor 62 is interposed between the + 5V terminal 63 and the anode of the semiconductor laser 12, the switching power supply Therefore, the laser output can be stabilized. In addition, the breakdown voltage of the semiconductor laser 12 against a sudden surge mixed from the + 5V terminal 63 increases.
[0036]
Since the semiconductor laser 12 has a specific cutoff frequency, and the problem of unnecessary radiation increases as the frequency f2 of the high-frequency signal HF is increased, the frequency of the high-frequency signal HF is generally set to 300 to 600 MHz. Is done. At that time, when the DVD-ROM is read at 16 × speed, it is necessary to increase the frequency f1 at which the gain of the current-voltage conversion circuit 15 becomes −3 dB to about 150 MHz. In the optical pickup head of the present invention, even if the band of the current-voltage conversion circuit is widened, it is extremely difficult to be influenced by high-frequency signals, so that an information recording / reproducing apparatus capable of reading information at high speed can be obtained.
[0037]
In the case of a conventional information recording / reproducing apparatus, the ratio of the frequency of the high-frequency signal HF and the frequency of the current-voltage conversion circuit needs to be increased to about 10 times or more, so the frequency band of the current-voltage conversion circuit will be expanded to 150 MHz. Then, the frequency of the high frequency signal had to be 1 GHz or more. As a result, in the conventional apparatus, the unnecessary radiation of the high-frequency signal becomes large and it becomes difficult to take countermeasures, or the frequency of the high-frequency signal becomes higher than the cutoff frequency of the laser and the laser is not modulated. was there. On the other hand, by using the optical pickup of the present invention, it becomes possible to satisfy the relationship of f2 / f1 ≦ 5, so that such a problem can be avoided.
[0038]
In the optical pickup head 10, only the insulating layer 32 exists between the electrode 33 connecting the semiconductor laser 12 and the semiconductor substrate 11. However, in the optical pickup head of the present invention, the semiconductor laser 12 mounted on the submount may be mounted on the insulating layer 32. As a result, since the resistance of the submount exists between the electrode 33 and the semiconductor substrate 11, the leakage of the high frequency signal HF to the first light receiving element 13 and the current-voltage conversion circuit 15 is reduced, and the high frequency signal HF is reduced. The effect of is further reduced. In this case, the specific resistance of the submount is preferably as large as possible.
[0039]
In the optical pickup of the present invention, a feedback type differential amplifier may be used for the current-voltage conversion circuit 15. In this case, the current signal from the first light receiving element 13 is input to the negative input of the differential amplifier, the reference voltage is input to the positive input of the differential amplifier, and a few pF or more is provided between the positive input and GND. It is preferable to provide a capacitor. With this configuration, mixing of the high-frequency signal HF into the current-voltage conversion circuit 15 via the semiconductor substrate 11 is input as an in-phase signal to the differential amplifier, and the influence of the high-frequency signal is further reduced. As the feedback type differential amplifier, for example, a configuration disclosed in FIG. 1 of Japanese Patent Laid-Open No. 8-45098 can be applied.
[0040]
In the first embodiment, the light receiving element has a simple pn structure. However, the light receiving element may have any structure. For example, a light receiving element having a pin structure formed by epitaxial growth may be used. It may be used.
[0041]
In the first embodiment, the case where the current signal output from the first light receiving element 13 is input to the output control circuit 61 has been described. However, when the output is controlled at high speed, the first light receiving element 13 is used. A current-voltage conversion circuit that converts a current signal output from the signal into a voltage signal may be formed on the semiconductor substrate 11. According to this configuration, since the output of the semiconductor laser 12 is stable, it is possible to realize an optical pickup head that is not easily affected by the high-frequency signal HF.
[0042]
In the first embodiment, the focus error signal is calculated using the Foucault method. However, various modifications can be made without departing from the spirit of the present invention.
[0043]
In the first embodiment, the optical pickup head based on the case where the semiconductor substrate 11 is p-type is shown, but the semiconductor substrate 11 may be n-type. The semiconductor substrate 11 may be formed of any semiconductor. There are no particular restrictions on the structure or wavelength of the semiconductor laser.
[0044]
The power supply voltage +5 V and the reference voltage +2.5 V are merely examples, and can be designed to have desired voltages.
[0045]
(Embodiment 2)
In the second embodiment, an example of the information recording / reproducing apparatus of the present invention will be described. In addition, about the part demonstrated in Embodiment 1, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.
[0046]
The configuration of the information recording / reproducing apparatus of Embodiment 2 is schematically shown in FIG. The information recording / reproducing apparatus according to the second embodiment is an apparatus that reproduces at least information from an optical storage medium, and may further record information.
[0047]
Referring to FIG. 7, the information recording / reproducing apparatus of Embodiment 2 includes optical pickup head 10 described in Embodiment 1, driving means 71, electric circuit 72, and power supply unit 73.
[0048]
The driving unit 71 changes the relative position between the optical storage medium 40 and the optical pickup head 10. The driving unit 71 includes a motor 71a and a driving unit 71b. The motor 71a rotates the optical storage medium 40. The drive unit 71b moves the optical pickup head 10. Specifically, a traverse mechanism using a linear motor, a rack opinion, or the like can be used as the drive unit 71b.
[0049]
The electric circuit 72 includes a signal processing circuit for obtaining information recorded on the optical storage medium 40 using a signal output from the optical pickup head 10. That is, the electric circuit 72 demodulates information recorded on the optical storage medium 40. In addition, a signal related to the position of the optical storage medium 40 is input from the optical pickup head 10 to the electric circuit 72. The electric circuit 72 amplifies or calculates this signal and moves the optical pickup head 10 or the objective lens 19 in the optical pickup head 10. The objective lens 19 is driven by an actuator 21. As the electric circuit 72, a circuit generally used in an information recording / reproducing apparatus can be used. The information recording / reproducing apparatus according to the second embodiment performs focus servo and tracking servo on the optical storage medium 40 by using the signal and the drive unit 71b or the actuator 21, and reads or writes information from or on the optical storage medium 40. Erase.
[0050]
The power supply unit 73 is a connection part to a power supply or an external power supply. Electricity is supplied from the power supply unit 73 to the driving means 71, the electric circuit 72, and the actuator 21. Note that a connection terminal for a power supply or an external power supply may be provided in each drive circuit.
[0051]
Although the embodiments of the present invention have been described above by way of examples, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating an exemplary configuration of an optical pickup head according to the present invention.
2 is a top view of a semiconductor substrate of the optical pickup head shown in FIG. 1. FIG.
3 is an enlarged view schematically showing a part of a semiconductor substrate of the optical pickup head shown in FIG. 1. FIG.
4 is a diagram schematically showing a hologram element of the optical pickup head shown in FIG. 1. FIG.
FIG. 5 is a diagram showing an example of a current-voltage conversion circuit that can be used in the optical pickup head shown in FIG.
FIG. 6 is a diagram schematically showing the function of the optical pickup head of the present invention.
FIG. 7 is a diagram schematically showing an example of the information recording / reproducing apparatus of the present invention.
FIG. 8 is a diagram illustrating an example of a semiconductor substrate of a conventional optical pickup head.
[Explanation of symbols]
10 Optical pickup head
11 Semiconductor substrate
11a recess
11b Reflective surface
12 Semiconductor laser
12a GaAs substrate
12b Semiconductor layer
13 First light receiving element
13a, 13b, 13c, 13d
14 Second light receiving element
15, 15a, 15b, 15c, 15d, 51 Current-voltage conversion circuit
16 Optical system
17 Hologram element
17a, 17b, 17c region
17d axis
18 Collimating lens
19 Objective lens
20 aperture
21a, 21b Actuator
22 packages
23 Wiring
30, 31 Laser beam
30a, 30b, 30c Diffracted light
32 Insulating layer
33 electrodes
40a transparent substrate
40b Information recording surface
51 operational amplifier
52 resistance
53 capacitors
61 Output control circuit
62 Transistor
63, 68, 69 terminals
64 resistance
65 inductor
66 Oscillator
67 Coupling capacitor
71 Driving means
71a motor
71b Drive unit
72 Electric circuit
73 Power supply

Claims (5)

A semiconductor substrate;
A semiconductor laser mounted on the semiconductor substrate via an insulating layer ;
A light receiving element that receives a laser beam emitted from the semiconductor laser and reflected by an optical storage medium, and outputs a current signal corresponding to the amount of the received laser beam;
A current-voltage conversion circuit that converts the current signal into a voltage signal;
In the semiconductor laser, when the surface close to the insulating layer is the first surface,
The semiconductor laser receives a high-frequency signal from the first surface for preventing the output of the semiconductor laser from fluctuating due to the laser beam reflected by the optical storage medium entering the semiconductor laser. An optical pickup head in which the light receiving element and the current-voltage conversion circuit are monolithically formed on the semiconductor substrate.   The optical pickup head according to claim 1, wherein the semiconductor substrate is p-type.   The semiconductor laser includes a substrate and an active layer formed above the substrate, and is mounted on the semiconductor substrate such that the active layer is closer to the semiconductor substrate than the substrate. The optical pickup head according to 1 or 2.   4. The optical pickup head according to claim 1, wherein a frequency f1 at which a gain of the current-voltage conversion circuit is −3 dB and a frequency f2 of the high-frequency signal satisfy a relationship of f2 / f1 ≦ 5. An information recording / reproducing apparatus that reproduces at least information from an optical storage medium,
An optical pickup head according to any one of claims 1 to 4,
Driving means for changing a relative position between the optical storage medium and the optical pickup head;
An information recording / reproducing apparatus comprising: a signal processing circuit that obtains information recorded on the optical storage medium using a signal output from the optical pickup head.

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