KR20060072378A - Integration optical unit and optical pick-up apparatus - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pick-up apparatus, and more particularly, to an integrated optical unit having three light emitting units and corresponding light receiving units for integration of an optical device, a prism for changing an optical path, and an optical pickup apparatus using the same.

An integrated optical unit according to an embodiment of the present invention includes a reflector having three inclined surfaces, three laser diodes facing each of the inclined surfaces, and a photo detector opposed between the inclined surfaces, thereby reducing the relative distance between the three laser diodes. In addition, the height of the optical pickup can be lowered through integration.

Optical pickup, 3 wavelength, prism

Description

INTEGRATION OPTICAL UNIT AND OPTICAL PICK-UP APPARATUS}

1 is a block diagram showing a conventional optical pickup device.

2 is a view showing a conventional three-wavelength diode.

3 is another configuration diagram of a conventional three-wavelength diode.

4 is a perspective view illustrating an integrated optical unit according to an exemplary embodiment of the present invention.

5 is a plan view of FIG.

6 is a schematic structural diagram showing an integrated optical unit and a hologram element according to the present invention;

7 is a side view showing an integrated optical unit and a hologram element according to the present invention.

8 is a block diagram showing a light emitting and receiving path of the integrated optical unit according to the present invention.

9 is a detailed configuration diagram of a hologram element according to the present invention.

10 is a block diagram showing a light detection example of the photodetector according to the present invention.

11 is a block diagram of an optical pickup device using an integrated optical unit according to the present invention.

12 shows a comparison of the relative distance between laser diodes of an integrated optical unit according to the invention.

13 illustrates aberration characteristics according to relative distances between laser diodes according to the present invention;

<Description of the symbols for the main parts of the drawings>

100 ... Integrated Optical Units 101,102,103 ... Laser Diodes

104 ... Stem 110 ... Reflective

111,112,113 ... inclined surface 130 ... light detector

140 Hologram element 151 Collimator lens

152 ... reflective mirror 153 ... objective lens

154 disc

SUMMARY OF THE INVENTION The present invention relates to an integrated optical system, in which an optical pickup device is integrally provided with at least two laser diodes and corresponding photo diodes for the integration of an optical device, and a reflector for changing an optical path therebetween. A unit and an optical pickup apparatus using the same.

As moving picture information such as movies is compressed, optical discs such as compact discs (CDs) and digital versatile discs (DVDs) are also required to store digital video signals for about two hours. However, the DVD having the largest recording capacity among optical disks can record only up to 4.7 GBytes, which is not suitable for recording two hours of moving picture information.

Recently, recording and playback devices for BD (Blu-ray Disc) have been developed, which has emerged as a superb concern as high-definition digital broadcasting has spread worldwide. The blue laser diode (BD) class optical recording / reproducing apparatus uses laser light having a high numerical aperture (for example, NA = 0.85) and a short wavelength (for example, 405 nm).

As a double word, a disc recording and reproducing apparatus uses various media such as DVD, CD, and BD (Blue-ray Disc), and therefore, since a single laser cannot reproduce all the discs, an optical signal corresponding to two or three wavelengths is required. A recording and reproducing apparatus is necessary.

1 is a block diagram showing a conventional three-wavelength optical pickup apparatus.

Referring to FIG. 1, laser beams are generated from the first to third laser diodes 11, 12 and 13 and the first to third laser diodes 11, 12 and 13 to generate beams having different wavelengths. Beam splitters 21, 22 and 23 for transmitting or reflecting light beams according to the incident direction, collimator lens 24 for converting beams reflected by the beam splitters 21, 22 and 23 into parallel beams, and the parallel beams A reflection mirror 25 for switching the path in the direction of the objective lens, an objective lens 26 for irradiating the disk 27 with the beam reflected by the reflection mirror 25, and reflection from the disk 27. It is the structure containing the photodetector 30 which receives the reflected light beam.

Here, the first laser diode 11 is for CD, the second laser diode 12 is for DVD, and the third laser diode 13 is used for BD as a blue laser diode.

Accordingly, the laser beams generated from the first, second, and third laser diodes 11, 12, and 13 installed separately are reflected through the respective beam splitters 21, 22, and 23 to match the paths of the light beams. . That is, the beam 780 nm generated from the first laser diode 11 is reflected by the first beam splitter 21, passes through the third beam splitter 23, and enters the collimator lens 24. The beam 680 nm generated from the diode 12 is reflected by the second beam splitter 22, passes through the first and third beam splitters 21 and 23 and enters the collimator lens 24, and the third laser diode ( The beam 405 nm generated from 13 is reflected by the third beam splitter 23 and is incident on the collimator lens 24. This reflection or transmission operation may vary depending on the installation position of the laser diode.

The collimator lens 24 is converted into a parallel beam by the incident beam, the path is switched in the direction of the disk by the reflecting mirror 25 and then irradiated to the disk 27 by the objective lens 26. The light irradiated onto the disk 27 is reflected and transmitted through the beam splitters 23, 21, and 22 through the reverse path, that is, the objective lens 26, the reflecting mirror 25, and the collimator lens 24, and the photodetector ( 30) is detected as an electrical signal, used as a server signal and RF signal.

Thus, when constituting a three-wavelength-compatible optical system using the laser diodes (11, 12, 13) separately disposed as described above, a lot of optical components are required, so a two-wavelength laser diode has been developed.

2 is a conventional three-wavelength laser diode package, which forms two laser diodes in one light emitting element 41 to generate a laser beam for a CD and a laser beam for a DVD. The two light emitting elements 42 are stacked to generate a BD laser beam. Accordingly, the optical parts corresponding to the two beam splitters may be removed from FIG. 1 and the space may be utilized.

3 shows another example of a conventional three-wavelength laser diode, and generates a laser beam for a CD, a DVD, and a BD through three light emitting elements 43, 44, and 45 arranged horizontally.

However, conventionally, even when using a three-wavelength laser diode package, there is a limit to reduce the distance (100um) because the two adjacent laser diodes are placed on a straight line, there is a problem that degradation of the temperature characteristics and deterioration characteristics of the LD.

The first object of the present invention is to integrate three laser diodes and a photo detector for receiving light into one unit for three wavelengths.

The second object of the present invention is to reduce the relative distance between the laser diodes by including a reflector having an inclined plane at an angle, three laser diodes at each inclined plane, and an integrated optical unit for integrally mounting a light detector between the conformal planes. To reduce the number of optical components.

A third object of the present invention is to provide a hologram element on the integrated optical unit, thereby guiding the light in a desired direction so that the reflected light beam can be received by the light detector.

Integrated optical unit according to the present invention for achieving the above object,

A reflector in which three inclined surfaces are formed at a conformal angle;

Three laser diodes facing each of the inclined surfaces;

A photo detector disposed between the two inclined surfaces and between two laser diodes;

And a stem for supporting the laser diode and the photo detector.

In detail, the inclined surfaces of the reflectors may be inclined at 45 degrees with respect to the step bottom reference or the emission optical axis, respectively.

Specifically, the reflector is characterized in that formed in a pyramid shape.

Specifically, the inclined surfaces of the reflector is characterized in that formed at intervals of 120 degrees to each other.

Specifically, the upper portion of the reflector is characterized in that it further comprises a hologram element for transmitting the light beams reflected through each inclined surface on the optical path, and the reflected light beam reflected from the disk to the light detector.

Specifically, the reflector is characterized in that the reflective prism or reflective mirror.

An optical pickup apparatus using an integrated optical unit according to another embodiment of the present invention,

First to third laser diodes for generating light beams having different wavelengths according to the type of optical disk, an optical detector disposed between two laser diodes, for receiving a reflected light beam and detecting the detected electrical signal, and the three laser diodes An integrated optical unit comprising a reflector reflecting a beam by opposing each inclined surface;

A hologram element disposed above the integrated optical unit to transmit and diffract along the polarization direction of the beam;

Means for converting the light beam emitted from the integrated optical unit into a parallel beam;

Optical path switching means for switching the parallel beam in the direction of the disc;

And an objective lens for condensing the light beam converted by the optical path switching means on the disk.

Specifically, the hologram device is characterized in that a small diffraction region and a dense diffraction region are formed to transmit and diffract the beam.

The present invention provides three laser diodes and a photo detector for placing a reflector such as a prism or mirror having three inclined surfaces at the center of a circular stem, and generating a light beam having a different wavelength around the reflector so as to face the inclined surfaces of the reflector. By installing in a package, it is possible to generate three light beams in one unit and to receive the reflected light beam, thereby simplifying the configuration of the optical pickup device and minimizing the volume.

Hereinafter, with reference to the accompanying drawings as follows.

4 and 5 are a perspective view and a plan view of the integrated optical unit of the present invention.

4 and 5, an integrated optical unit (or module) 100 includes a stem 104 in the form of a circular or donas shape and first to third spaced apart at 120 degree intervals on the stem 104. Disposed between the two laser diodes and a reflector 110 having a laser diode (101, 102, 103), an inclined surface (111, 112, 113) disposed at an equiangular position at the center of the stem (104) to face the first to third laser diodes (101, 102, 103). It includes a photo detector 130.

Here, the reflector 110 is formed of a mirror, a prism, a structure having a reflective film attached to an inclined surface, or the like.

4 and 5, the integrated optical unit 100 may have first to third laser diodes LD1, LD2, and LD3 at an isometric angle (120 degrees) on a circular or donas-shaped stem 104. 101, 102 and 103 are disposed, and the photo detector 130 is disposed between the two laser diodes 101 and 103, respectively.

Here, the stem 104 may be separated into three, and the first, second, and third laser diodes 101, 102, and 103 may be mounted and then assembled. That is, the three-wavelength laser diode and the light detection unit may be manufactured by fabricating stems on which one laser diode (101, 102, 103) is mounted, and then attaching them in a circular structure around the reflector 110 and installing a light detector.

The first to third laser diodes 101, 102, and 103 are disposed at equal intervals in three equal portions to face the inclined surfaces 111, 112, and 113 of the reflector 110, respectively. The inclined surfaces 111, 112, and 113 of the reflector 110 are formed to be inclined at a predetermined angle with respect to the bottom of the stem 104 or the optical axis, for example, may be manufactured to be inclined at 45 degrees. In this case, the inclined surfaces 111, 112, and 113 may have a narrower or wider angle of inclination. This may adjust the spacing between beams generated from the different laser diodes 101, 102, 103 by the inclined plane angle.

Each of the inclined surfaces 111, 112, and 113 may be spaced apart from each other by 120 degrees, and the reflector 110 may have a pyramid shape. The photo detector 130 is installed between the inclined surfaces of the reflector 110, that is, the position opposite to the corners.

Light beams having different wavelengths generated by the first to third laser diodes 101, 102 and 103 are reflected on the first to third inclined surfaces 111, 112 and 113 of the reflector 110 in a direction perpendicular to the surface of the stem 104. Will proceed. The laser beams of different wavelengths thus proceeded can be used for recording or playing back heterogeneous disks.

Here, the first light source used in the first laser diode (LD1) 101 is, for example, a laser diode for irradiating light of 780 nm wavelength, and is used as a CD disk. The second light source generated by the second laser diode (LD2) 102 is, for example, a laser diode for CD for irradiating light of 680 nm wavelength, and is used as a disk for DVD. The third light source used in the third laser diode 103 may be, for example, a blue laser diode that emits light having a wavelength of 405 nm.

In addition, the reflected light beam reflected from the disk is concentrated by the hologram element to the photodetector 130 disposed between the first and third laser diodes 101 and 103, thereby detecting the electrical signal in the photodetector 130 as a server signal. And RF signals.

6 to 8 are provided with a hologram element 140 on the integrated optical unit 100.

First, referring to FIGS. 6 and 7, a hologram element 140 for transmitting a beam to a desired position is coupled to the integrated optical unit 100.

As shown in FIG. 8, the laser beams B1, B2, and B3 generated from the first to third laser diodes 101, 102, and 103 are reflected at right angles to the first to third inclined planes 111, 112, and 113 of the reflector 110, respectively. 140 passes through and exits the light path. The emitted light beam passes through the optical path to access heterogeneous disks. The reflected light beam reflected by the disk is transmitted through the hologram element 140 in the reverse path. At this time, the reflected light beam is focused on the photodetector 130 directly through the hologram element 140.

That is, since the hologram element 140 transmits the reflected light beam reflected from the disk and incident in the reverse path directly to the photo detector 130 without passing through the inclined plane, the optical pickup may be implemented in a stable state without requiring additional adjustment. .

For this purpose, the hologram element 140 is composed of a small diffraction region 142 and a dense diffraction region 141, as shown in FIG. That is, the hologram element 140 has a diffraction region in which the diffraction grating is engraved in the horizontal direction and the diagonal direction, and the diffraction region is divided into a dense region 141 and a small region 142 and transmits a beam according to the polarization direction. And diffraction.

10 is a configuration diagram illustrating a hologram element 140 and a photo detector 130 according to the present invention.

Referring to FIG. 10, the reflected light beam transmitted through the hologram element 140 is received by the cells C1, C2, C3, and C4 having a four-division structure included in the photodetector 130. The photo detector 130 receives the reflected light beam transmitted through the hologram element 140. The photo detector 130 receives the main light and the sub light through the cells C1, C2, C3, and C4 having a four-division structure, and converts the light into electrical signals. By detecting, the server signal and the RF signal are detected.

11 is a block diagram showing an optical pickup device using an integrated optical unit of the present invention.

Referring to FIG. 11, an integrated optical unit 100 that emits laser beams B1, B2, and B3 having different wavelengths and receives a reflected light beam, and a beam generated from the integrated optical unit 100 as a parallel beam. A collimator lens 151 for switching, a reflection mirror 152 as an optical path switching means for changing the optical path of the parallel beam in the disc direction, and an objective lens 153 for irradiating the disk 154 with the reflected laser beam ) Is a configuration that includes.

The optical pickup device using the integrated optical unit is first converted into parallel beams by the collimator lens 151 when beams B1, B2, and B3 having different wavelengths are respectively generated from the integrated optical unit 100. The optical path is changed in the disc direction by the reflective mirror 152 and then irradiated onto the disc 154 through the objective lens 153. In addition, the reflected light beam reflected from the disk 154 is received by the optical detector 130 of the integrated optical unit through the reverse path, that is, the objective lens 153, the reflection mirror 152, and the collimator lens 151.

12 is a view comparing the distance between the laser diode (LD1, LD3) according to the present invention. The first and second light beams B1 'and B3' generated by the existing first and second laser diodes LD1 and LD3 are spaced apart from each other by a predetermined distance d3 (about 100um).

In contrast, in the present invention, the distance between the first light beam B1 generated by the first laser diode LD1 101 and the third light beam B3 generated by the third laser diode LD3 103 is conventional. It can maintain a smaller interval (d2, about 50um). In addition, when the inclination angle of the inclined surface of the reflector 110 is made smaller, it may be narrowed up to a distance d3 (about 30 um) between the relative beams B1 and B3 ″ by the virtual point. Alternatively, the position of the laser diode may be relatively The distance between the beams may be narrowed by placing at a position higher than the reflector 110.

In addition, according to the present invention, the relative distance between the three laser diodes disposed at equal angles to each other may be constantly adjusted by adjusting the angle of each inclined surface of the reflector 110.

13 is a graph showing the relationship between elevation and aberration (RMS) according to the distance between laser diodes according to the present invention. Here, the image is a distance between the first laser diode LD1 and the second laser diode LD2. In the present invention, the distances A and B between beams and the distance C between conventional beams are compared. As shown, the distances between the beams of the first laser diode LD1 and the second laser diode LD2 represent 30um, 50um and the conventional 100um, and the magnitude of each of the relative aberration differences is A> B> C. appear.

Here, the larger the aberration difference, the more problems occur in the pickup, the first relative inclination occurs, causing problems with tilt adjustment and residual skew unconditionally. The use of a second photodetector produces a relative difference in the beam received. The present invention solves this problem.

So far, the present invention has been described with reference to the preferred embodiments, and those skilled in the art to which the present invention pertains to the detailed description of the present invention and other forms of embodiments within the essential technical scope of the present invention. Could be implemented. Here, the essential technical scope of the present invention is shown in the claims, and all differences within the equivalent range will be construed as being included in the present invention.

As described above, according to the integrated optical unit and the optical pickup device using the same in the optical pickup device according to the present invention, a reflector having an inclined surface arranged at an angle, three laser diodes and an optical detector facing each other are integrated into one package. By configuring the optical unit, there is an effect that can be implemented in a stable state that does not require additional adjustment according to the mounting of the photo detector.

In addition, by integrating three laser diodes, the number of optical components can be reduced and the cost can be reduced.

In addition, by improving the relative distance between the laser diode, there is an effect that can remove the aberration due to the bent axis caused by the relative distance as in the conventional.

It also has the effect of lowering the overall height of the pickup.

Claims (8)

A reflector in which three inclined surfaces are formed at a conformal angle; Three laser diodes facing each of the inclined surfaces; A photo detector disposed between the two inclined surfaces and between two laser diodes; And a stem for supporting the laser diode and the photo detector. The method of claim 1, And an inclined surface of the reflector is inclined at 45 degrees with respect to the step bottom reference or the light emitting optical axis, respectively. The method of claim 1, The reflector is an integrated optical unit, characterized in that formed in a pyramid shape. The method of claim 1, And the inclined surfaces of the reflectors are formed at 120 degree intervals from each other. The method of claim 1, And a hologram element disposed above the reflector to transmit the light beams reflected through the inclined surfaces on the optical path, and to collect the reflected light beams reflected from the disc to the light detector. The method of claim 1, And said reflector is a reflecting prism or a reflecting mirror. First to third laser diodes for generating light beams having different wavelengths according to the type of optical disk, an optical detector disposed between two laser diodes, for receiving a reflected light beam and detecting the detected electrical signal, and the three laser diodes An integrated optical unit comprising a reflector reflecting a beam by opposing each inclined surface; A hologram element disposed above the integrated optical unit to transmit and diffract along the polarization direction of the beam; Means for converting the light beam emitted from the integrated optical unit into a parallel beam; Optical path switching means for switching the parallel beam in the direction of the disc; And an objective lens for condensing the light beam converted by the optical path switching means onto a disk. The method of claim 7, wherein The hologram device is an optical pickup device using an integrated optical unit, characterized in that a small diffraction region and a dense diffraction region are formed to transmit and diffract the beam.

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