JP2006065908A - Optical pickup apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup apparatus in which the power loss of a laser beam is not caused when a part of outgoing light is detected and power monitoring of the laser beam is performed, and high position accuracy is not required for assembling a reflection mirror. <P>SOLUTION: In the optical pickup apparatus 1 recording or reproducing data by irradiating a recording plane of an optical disk with the laser beam, the apparatus is provided with a reflection plane 11 reflecting light of an outside part of the laser beam emitted from a laser output means 21, an optical sensor 15 for power monitoring receiving the light converged by this reflection plane and detecting emission intensity of the laser output means 21, and an opt-base 10 to which the laser output means 21 and each optical parts 22 to 27 are attached, the reflection plane 11 is integrally formed at the opt-base 10 as a part of the opt-base 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup device that records or reproduces data by irradiating an optical disc with laser light, and relates to a technique for monitoring the output power of laser light.

  In the past, control of keeping the output intensity of laser light constant has been performed by monitoring and feeding back the output power of laser light in an optical pickup. A low-power semiconductor laser has a part of the laser beam leaking to the opposite side of the laser emission direction. Since the semiconductor laser is configured to emit almost 100% of the laser light in the emission direction, it is necessary to monitor a part of the emitted laser light and use it for feedback control.

  Conventionally, as a method for monitoring a part of the laser light in this way, there has been adopted a method in which, for example, light outside the effective diameter of the collimating lens is reflected by a reflecting mirror and guided to a monitoring optical sensor. Here, the reflecting mirror is bonded and fixed to the base body of the optical pickup.

In addition, there is one that uses a prism or the like to guide a part of light to a monitoring optical sensor (for example, Patent Document 1). In addition, although it is a technique different from the laser power monitor, there has been a proposal in which a reflection mirror that reflects laser light toward the objective lens is integrally formed with the base of the objective lens actuator (for example, Patent Document 2).
JP 2001-148137 A JP 2002-184000 A

  In order to monitor the power of the laser beam, it is not preferable that a part of the laser beam is branched and detected by a prism or the like as in Patent Document 1, because the power loss of the laser beam is generated accordingly.

  In addition, in a configuration in which a reflecting mirror is bonded and fixed to detect laser light outside the effective diameter for monitoring, the reflecting mirror does not enter the inside of the effective diameter of the laser light and hits a small part outside the effective diameter. There is a problem in that high accuracy is required for the mounting position of the reflecting mirror, for example, the amount of light to be reflected is reduced if the arrangement is shifted even a little, thereby leading to an increase in cost during assembly.

  The object of the present invention is to detect a part of the emitted light and monitor the power of the laser light without incurring a power loss of the laser light and when a high positional accuracy is required for assembling the reflecting mirror. Needless to say, an object of the present invention is to provide an optical pickup device that does not increase the cost of assembly.

  In order to achieve the above object, the present invention provides an optical pickup apparatus for recording or reproducing data by irradiating a recording surface of an optical disc with a laser beam, from a laser output means for outputting the laser beam, and a recording surface of the optical disc. A first optical sensor that receives the reflected light reflected; an optical system that guides the laser light emitted from the laser output means to a recording surface of the optical disk and guides the reflected light from the optical disk to the first optical sensor; A reflection surface that reflects light of an outer portion of the laser light emitted from the laser output means; a second optical sensor that receives the light collected by the reflection surface and detects the emission intensity of the laser output means; A base body to which the laser output means, the first optical sensor, the second optical sensor, and the optical system are attached, and the reflecting surface is a part of the base body. It has a configuration which is integrally formed on the base body.

  According to such means, since the reflection surface for reflecting a part of the laser beam for power monitoring is formed integrally with the base body, the optical pickup is compared with the case where the reflection surface is bonded and fixed to the base body. As a result, the accuracy of the position and angle of the reflecting surface can be greatly increased.

  Desirably, the reflecting surface may be formed by mirror-processing a part of the base body. With this configuration, it is possible to increase the reflectance from the reflecting surface to the second sensor and increase the detection amount of the laser light for power monitoring. Thereby, the feedback control of the laser output intensity can be performed stably.

  Specifically, the base body is preferably made of aluminum, and the reflecting surface is preferably polished to be a mirror surface. With such a configuration, it is possible to form a base body having a reflecting surface composed of a mirror surface at low cost.

  More preferably, the reflecting surface is formed in a curved surface shape for collecting the reflected light. Thereby, the detection amount of the laser beam for power monitoring can be increased.

  Desirably, the focal position of the reflected light by the reflecting surface is set to a position displaced in a direction away from the reflecting surface from the mounting surface of the second photosensor of the base body. By shifting the focal position in this manner, the reflected light can be condensed on the detection surface of the optical sensor in an optimum state by fine adjustment of the mounting position of the second optical sensor.

  According to the present invention, the power of the outer portion of the laser beam is condensed on the second optical sensor by the reflecting surface and the power monitoring is performed. Therefore, the power loss of the laser beam irradiated on the optical disk is not caused, and this reflection is not caused. Since the surface is integrally formed with the base body of the optical pickup device, the positional accuracy can be very high, and the assembly process can be reduced by one compared with the case where the reflective surface is bonded and fixed. There is an effect that the cost of time can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view of a part of a longitudinal section of an optical pickup device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part thereof. FIG. 3 is a top view (a) and a side view (b) showing an optical system configuration provided in the optical pickup device.

  The optical pickup device 1 of this embodiment records and reproduces data on an optical disk such as a writable DVD (digital versatile disk), for example, as shown in FIG. Various optical components and an objective lens actuator 30 are assembled to an opt base (base body) 10 formed by integrally molding aluminum.

  Here, as an optical component, a semiconductor laser (laser output means) 21 that outputs a laser, a diffraction grating 22 that forms a beam, a polarization beam splitter 23 that separates a laser beam traveling to a disk and reflected light, and a polarization beam In order to split the reflected light efficiently by the splitter 23, a quarter-wave plate 24 that rotates the phase of the reflected wave by 90 degrees with respect to the traveling wave, a rising prism mirror 25, a collimating lens 26 that converts the laser light into parallel light, An objective lens 27 for focusing the laser beam on the recording surface of the optical disk, an optical sensor 15 for power monitoring of the semiconductor laser 21, and a cylindrical lens 28 for giving astigmatism to the separated reflected light (not shown in FIG. 1). (FIG. 3A), an optical sensor 29 that receives reflected light (FIG. 3A), and the like. The objective lens actuator 30 minutely moves the objective lens 27 in the focus direction, tracking direction, and tilt angle direction by electromagnetic force.

  The power monitoring optical sensor 15 receives light reflected between the diffraction grating 22 and the polarization beam splitter 23 and monitors the output power of the semiconductor laser 21.

  FIG. 4 is a diagram illustrating the outline of the emitted light of the semiconductor laser, the effective diameter of the collimating lens, and the reflection range by the reflecting surface.

  A curved reflecting surface 11 is formed in the upper part of the space between the diffraction grating 22 and the polarizing beam splitter 23 as shown in detail in FIG. As shown in FIGS. 1 and 2, the reflecting surface 11 is a part of an aluminum opto-base 10. For example, a rotating paraboloid is used to focus the laser beam incident on this part on a predetermined position. It is formed in a curved surface such as a surface, and is mirror-finished by a polishing process or the like.

  The laser light incident on the reflecting surface 11 is reflected and travels toward the light receiving surface of the monitoring optical sensor 15. As shown in FIG. 4, the emitted light F of the semiconductor laser 21 has an elliptical outline, and both end portions of the major axis are outside the effective diameter R0 corresponding to the numerical apertures of the collimating lens 26 and the objective lens. Come off. The light irradiated and reflected on the reflecting surface 11 is light of the long-axis one-side portion F2 deviating from the effective diameter R0.

  Further, the focal position P of the reflected light focused by the reflecting surface 11 is set to be farther from the mounting surface of the optical sensor 15. The optical sensor 15 is formed with a photodiode in a small area S at the center, and the reflected light from the reflecting surface 11 is applied to a certain range in the area S to detect the light quantity. .

  FIG. 5 shows an exploded perspective view of the optical pickup device 1.

  In the figure, reference numeral 30 denotes the above-described objective lens actuator, and an objective lens holder to which the objective lens 27 is fixed by generating an electromagnetic force by the coils 33a to 33c and the magnets 34 and 34 by flowing current from the wires 35. 32 is slightly driven with respect to the actuator base 31. Reference numeral 40 denotes an FPC (Flexible Printed Circuit: wiring film) on which wirings connected to the semiconductor laser 21 and the optical sensors 15 and 29 are formed. Reference numeral 41 denotes a connection part of the semiconductor laser 21 and reference numeral 42 denotes a connection part of the optical sensor 29. , 43 is a connection part of the optical sensor 15 for power monitoring, and 45 is a connector connected to an external wiring.

  FIG. 6 shows a bottom view of the optical pickup device 1 with the wiring film 40 and the power sensor 15 removed, and FIG. 7 shows a bottom view of the wiring film 40 and the optical sensor 15 attached. .

  As shown in FIG. 5, a collimator lens 26 and an objective lens actuator 30 are attached to the opt base 10 from the upper surface side, while the semiconductor laser 21, the diffraction grating 22, the optical sensor 29, and the cylindrical lens 28 are attached from the side surface. The remaining optical system (polarizing beam splitter 23, quarter wavelength plate 24, rising prism mirror 25) and power monitor optical sensor 15 are attached from the lower surface side of the opt base 10.

  As shown in FIG. 6, the optical path of the laser beam is provided on the lower surface side of the opt base 10 so that optical components (polarizing beam splitter 23, quarter wavelength plate 24, rising prism mirror 25) can be introduced to the mounting location. Opened in an exposed state. Accordingly, the reflecting surface 11 that reflects light outside the effective diameter of the semiconductor laser 21 is also exposed, and the reflected light from the reflecting surface 11 can be guided to the outside from the opening.

  As shown in FIG. 7, the power sensor 15 for power monitoring is attached to the lower surface side of the opt base 10 via a fixing frame 12 (see FIGS. 1 and 2) and is attached to the connection portion 43 of the wiring film 40. The wiring power is connected so that the output power of the semiconductor laser 21 can be monitored. By finely adjusting the mounting position of the optical sensor 15 via the fixing frame 12, the amount of reflected light received can be maximized.

  As described above, according to the optical pickup device 1 of this embodiment, the reflecting surface 11 that reflects and collects light outside the effective diameter of the laser beam on the optical sensor 15 for power monitoring is integrated with the opt base 10. As a result, the number of assembling steps of the optical pickup device can be reduced by one and the accuracy of the position and angle of the reflecting surface 11 can be reduced as compared with the case where such a reflecting surface is bonded and fixed to the opto-base 10. Can be very high.

  Moreover, since the reflecting surface 11 is mirror-finished and is formed in a curved surface shape for condensing the reflected light, the reflectance of the reflecting surface 11 and the condensing rate to the optical sensor 15 are increased, and the laser output is increased. Feedback control can be performed stably.

  Moreover, since the mirror surface processing of the reflecting surface 11 is realized by polishing an opto-base made of aluminum, it can correspond to low cost.

  In addition, since the focal position of the reflected light by the reflecting surface 11 is set at a position away from the mounting surface of the optical sensor 15, an optimum state for the detecting surface of the optical sensor 15 by fine adjustment of the arrangement of the optical sensor 15. The reflected light can be collected with.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the position where the light outside the laser beam is reflected is an intermediate position between the diffraction grating 22 and the beam splitter 23. For example, the position immediately after the emission of the semiconductor laser, the position after the beam splitter, etc. It is not limited. In addition, the material of the opt base 10 and the method of mirror-finishing the reflecting surface 11 may be various materials and methods, such as a method of applying silver ink to the reflecting surface 11 using an opto base made of zinc alloy. I can do it.

  In addition, the details specifically shown in the embodiment such as the configuration of the optical system of the optical pickup and the type of recording medium for recording and reproduction can be changed as appropriate without departing from the spirit of the invention.

It is a longitudinal cross-sectional view of the optical pick-up apparatus of embodiment of this invention. It is a principal part enlarged view of FIG. FIGS. 1A and 1B show an optical system of the optical pickup device of FIG. 1, and FIG. It is a figure explaining the reflection range by the outline of the emitted light of a semiconductor laser, the effective diameter of a collimator lens, and a reflective surface. It is a disassembled perspective view of the optical pick-up apparatus of FIG. It is a bottom view of the state which removed the wiring film from the optical pick-up apparatus of FIG. FIG. 2 is a bottom view of the optical pickup device of FIG. 1.

Explanation of symbols

1 Optical pickup device 10 Opt base (base body)
DESCRIPTION OF SYMBOLS 11 Reflective surface 15 Optical sensor for power monitoring 21 Semiconductor laser 22 Diffraction grating 23 Polarizing beam splitter 24 1/4 wavelength plate 25 Rising prism mirror 26 Collimator lens 27 Objective lens 28 Cylindrical lens 29 Optical sensor 30 Objective lens actuator 40 Wiring film

Claims (6)

In an optical pickup device that records or reproduces data by irradiating a recording surface of an optical disc with a laser beam,
Laser output means for outputting the laser beam;
A first optical sensor for receiving reflected light reflected from the recording surface of the optical disc;
An optical system for guiding the laser beam emitted from the laser output means to the recording surface of the optical disc and guiding the reflected light from the optical disc to the first optical sensor;
A reflecting surface formed in a curved shape for reflecting and condensing the light of the outer portion of the laser light emitted from the laser output means;
A second optical sensor that receives the light collected by the reflecting surface and detects the emission intensity of the laser output means;
A base body to which the laser output means, the first optical sensor, the second optical sensor, and the optical system are made of aluminum;
The reflective surface is configured to be mirror-finished by polishing a part of the base body, and a focal position of reflected light by the reflective surface is determined from the mounting surface of the second photosensor on the base body. An optical pickup device, wherein the optical pickup device is set at a position displaced in a direction away from the reflecting surface. In an optical pickup device that records or reproduces data by irradiating a recording surface of an optical disc with a laser beam,
Laser output means for outputting the laser beam;
A first optical sensor for receiving reflected light reflected from the recording surface of the optical disc;
An optical system for guiding the laser beam emitted from the laser output means to the recording surface of the optical disc and guiding the reflected light from the optical disc to the first optical sensor;
A reflecting surface for reflecting the light of the outer portion of the laser light emitted from the laser output means;
A second optical sensor that receives the light collected by the reflecting surface and detects the emission intensity of the laser output means;
A base body to which the laser output means, the first optical sensor, the second optical sensor, and the optical system are attached;
The reflection surface is formed integrally with the base body as a part of the base body.   3. The optical pickup device according to claim 2, wherein the reflecting surface is formed by mirror-finishing a part of the base body.   4. The optical pickup device according to claim 3, wherein the base body is made of aluminum, and the reflection surface is polished to be a mirror surface.   The optical pickup device according to claim 2, wherein the reflection surface is formed in a curved surface shape for collecting the reflected light.   6. The light according to claim 5, wherein the focal position of the reflected light by the reflecting surface is set to a position displaced in a direction away from the reflecting surface from the mounting surface of the second photosensor of the base body. Pickup device.

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