KR20090132978A - Optical pick up - Google Patents

Abstract

PURPOSE: An optical pickup is provided to install a first object lens and a first optical detector in the same axis and install a first light source in an axis perpendicular to the installation axis of the first object lens and the first optical detector, thereby obtaining a free light incident structure at an angle of 0 to 180 degrees. CONSTITUTION: A DVD/CD(Digital Versatile Disc/Compact Disc) optical system(10) reproduces an optical disc(D1) for DVD/CD. A BD(Blu-ray Disc) optical system(50) reproduces an optical disc(D2) for BD. The DVD/CD optical system comprises a first light source(12), a first object lens(20), a first detector(22), a first beam splitter(16), and a first collimating lens(18). The first optical detector detects reflection light to change the reflection light into an electric signal. The first object lens changes light reflected to the optical disc for DVD/CD into collimated light. The first beam splitter transmits light irradiated from the first light source or reflects the light to a first object lens side. The first collimating lens changes beam reflected to the first beam splitter into collimated light.

Description

Optical pickup {OPTICAL PICK UP}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup. In particular, the objective lens and the photodetector are installed on the same axis so as to have a free incidence structure of 0 ° to 180 ° and the number of optical components installed on the optical path between the photodetector and the objective lens. It relates to an optical pickup that can reduce the volume and manufacturing cost of the optical pickup by reducing.

In general, an optical disc refers to a storage medium for recording / reproducing data such as voice, image, document, etc. by drilling a lot of pits on the surface thereof and changing the reflection of the laser light. Disc) and DVD (Digital Versatile Disc).

Recently, researches on high-density recording media with higher recording capacity than CDs or DVDs as next-generation optical discs are being actively conducted. Such high-density recording media include BD (Blu-ray Disc) and HD-DVD (High Definition Digital Versatile Disc). have.

On the other hand, the optical pickup refers to a device for reproducing the information stored in the optical disk by a non-contact method using a semiconductor laser, for this purpose, an optical system for reproducing the signal recorded on the optical disk or recording information is embedded in the optical pickup.

In this case, the optical system generally includes optical devices such as a light source LD, a diffraction grating GT, a collimating lens CL, a light splitter (or beam splitter, PBS), an objective lens OL, and a photodetector PD. Equipped.

Such optical pickup is currently required to be compatible with a widely used recording medium (CD or DVD) due to the development of a new recording medium (BD or HD-DVD).

As a result, in recent years, research on compatible optical pickups capable of reproducing information stored in both existing recording media (CD or DVD) and next-generation recording media (BD or HD-DVD) has been carried out in keeping with the development of new recording media. ought.

1 is a view showing the optical system configuration of the optical pickup according to the prior art, Figure 2 is a three-dimensional view showing the optical system configuration of the optical pickup shown in FIG.

1 and 2, the optical pickup according to the prior art is a DVD / CD optical system 100 for playing a DVD / CD optical disk (D1) and a BD optical system 200 for playing a BD optical disk (D2) It is composed of

The DVD / CD optical system 100 includes a first light source 102, a first grating element (GT) 104, a first beam splitter 106, a first collimating lens 108, a first mirror 110, A first objective lens 112, a first astigmatism lens (ASL) 114, and a first photodetector 116 are formed.

In the DVD / CD optical system 100, the first light source 102 and the first photodetector 116 are installed to be perpendicular to the same plane, and the first objective lens 112 is formed of the first light source 102 and the first light source. 1 The photodetector 116 is installed on an axis perpendicular to the axis on which it is installed.

In other words, as shown in FIG. 2, the first light source 102 is installed on the X axis of the three-dimensional space including the X axis, the Y axis, and the Z axis, and the first photodetector 116 is installed on the Z axis. The first objective lens 112 is provided on the Y axis.

At this time, when the first light source 102 is installed on the Z axis, the first photodetector 116 is installed on the X axis.

The DVD / CD optical system 100 emits light having a wavelength suitable for reproducing the optical disc D1 for the DVD / CD, when the first light source 102 emits light of the first light source 102 and the first beam splitter 106. The first grating element 104 disposed between the first and second grating elements 104 divides the light emitted from the first light source 102 to form a three-beam for detecting the tracking signal.

In this case, the divided beam is transmitted to the first beam splitter 106, which transmits or reflects toward the first mirror 110 according to the polarization component of the light split by the first grating element 104. Let's do it.

The beam reflected by the first beam splitter 106 is converted into parallel light by the first collimating lens 108, and the parallel light is perpendicular to the first objective lens 112 by the first mirror 110. (90 °) is reflected.

Accordingly, the first objective lens 112 focuses the light transmitted through the first mirror 110 to form a spot on the optical disc D1 for the DVD / CD.

That is, the first objective lens 112 focuses the light emitted from the first light source 102 to the optical disc D1 for DVD / CD at one point.

The reflected light reflected from the optical disc D1 for DVD / CD is provided with the first objective lens 112, the first mirror 110, the first collimating lens 108, the first beam splitter 106, and the first ratio. The light is focused on the first photodetector 116 through the score difference lens 114, and the first photodetector 116 collects the light reflected from the optical disk D1 for the DVD / CD and converts the light into an electrical signal.

In this case, the first astigmatism lens 114 is installed between the first photodetector 116 and the first beam splitter 106 so that the light reflected from the optical disk D1 for DVD / CD is reflected by the first photodetector 116. Make sure the spots are formed correctly.

The BD optical system 200 includes a second light source 202, a second grating element 204, a second beam splitter 206, a second collimating lens 208, a second mirror 210, and a mask. ) 218, a second objective lens 212, a second astigmatism lens 214, and a second photodetector 216.

In the BD optical system 200, the second light source 202 and the second photodetector 216 are installed to be perpendicular to the same plane, and the second objective lens 212 is provided with the second light source 202 and the second light. The detector 216 is installed on an axis perpendicular to the installed axis.

In other words, the second light source 202 is installed in the X-axis, the second photodetector 216 is installed in the Z-axis, and the second objective lens 212 in the three-dimensional space consisting of the X-axis, the Y-axis, and the Z-axis. ) Is installed on the Y axis.

At this time, when the second light source 202 is installed on the Z axis, the second photodetector 216 is installed on the X axis.

The BD optical system 200 is installed between the second light source 202 and the second beam splitter 206 when the second light source 202 emits light having a wavelength suitable for reproducing the optical disc D2 for BD. The second grating element 204 divides the light emitted from the second light source 202 to diffract to form a three-beam for tracking signal detection.

At this time, the divided beam is transmitted to the second beam splitter 206, which transmits or reflects toward the second mirror 210 according to the polarization component of the light split by the second grating element 204. Let's do it.

The beam reflected by the second beam splitter 206 is converted into parallel light by the second collimating lens 208, and the parallel light is perpendicular to the second objective lens 212 by the second mirror 210. (90 °) is reflected.

Parallel light reflected by the second mirror 210 toward the second objective lens 212 is transmitted to the second objective lens 212 through the mask 218, and the second objective lens 212 is the mask 218. A spot is formed on the optical disc D2 for BD by condensing the light transmitted through the < RTI ID = 0.0 >

That is, the second objective lens 212 condenses the light emitted from the second light source 202 to the BD optical disk D2 at one point.

The reflected light reflected by the optical disc D2 for BD includes the second objective lens 212, the mask 218, the second mirror 210, the second collimating lens 208, the second beam splitter 206, and the like. The light is collected by the second photodetector 216 through the second astigmatism lens 214, and the second photodetector 216 condenses the light reflected by the optical disc D2 for BD and converts the light into an electrical signal.

At this time, the second astigmatism lens 214 is installed between the second photodetector 216 and the second beam splitter 206 so that the light reflected from the BD optical disk D2 is spotted on the second photodetector 216. Make sure this is correct.

In the optical pickup according to the related art, since the photodetectors 116 and 216 and the objective lenses 112 and 212 for detecting the light reflected from the optical disk D1 for the DVD / CD are installed on different axes, the optical pickup reflects the optical disk. A large number of optical components for reproduction of DVD / CD and BD are used, such as mirrors 110 and 210 for transferring the collected light to the photodetectors 116 and 216.

As described above, the optical pickup according to the prior art has a problem that the incident structure is not free due to the use of a large number of optical components, the volume of the optical pickup is increased, and the manufacturing cost of the optical pickup is increased.

Accordingly, the present invention is to solve the above-described problems, by installing the objective lens and the photodetector on the same axis to have a free incidence structure of 0 ° ~ 180 ° and on the optical path between the photo detector and the objective lens It is an object of the present invention to provide an optical pickup that can reduce the volume and manufacturing cost of the optical pickup by reducing the number of optical components installed.

Optical pickup according to an embodiment of the present invention is a DVD / CD optical system for playing an optical disc for DVD / CD; And a BD optical system for reproducing an optical disc for BD, wherein the DVD / CD optical system includes: a first light source for emitting light necessary for reproducing the optical disc for DVD / CD; A first photodetector installed on an axis perpendicular to the axis on which the first light source is installed to detect reflected light reflected from the optical disc for DVD / CD and convert the reflected light into an electrical signal; Installed on the same axis as the first photodetector to condense the light emitted from the first light source so that the light emitted from the first light source forms a spot on the optical disc for DVD / CD, and in the optical disc for DVD / CD A first objective lens for converting the reflected light into parallel light; A first beam splitter disposed between the first photodetector and the first objective lens and configured to transmit or reflect light emitted from the first light source toward the first objective lens; And condensed between the first beam splitter and the first objective lens to focus the parallel light to form a spot on the first photodetector, and convert the reflected beam reflected by the first beam splitter into parallel light. It characterized in that it comprises a first collimating lens.

The optical pickup according to the embodiment of the present invention further includes a first grating device disposed between the first light source and the first beam splitter and diffracting and dividing the light emitted from the first light source.

In the optical pickup according to an embodiment of the present invention, the first light source is installed on any one of an X axis and a Z axis in a three-dimensional space including an X axis, a Y axis, and a Z axis, and the first objective lens and the first object. One photodetector is mounted on the Y axis.

In the optical pickup according to an embodiment of the present invention, the BD optical system includes: a second light source for emitting light necessary for reproducing the optical disc for BD; A second photodetector for detecting reflected light reflected from the BD optical disk and converting an optical signal into an electrical signal; A second objective lens for condensing the light emitted from the second light source such that the light emitted from the second light source forms a spot on the optical disc for BD; A mirror that vertically reflects the light emitted from the second light source and transmits the light to the second objective lens; A second grating element provided on the output side of the second light source to diffract and split light emitted from the second light source; A second beam splitter disposed between the mirror and the second photodetector to transmit or reflect toward the mirror according to the polarization component of the light split by the second grating element; A second collimating lens installed between the second beam splitter and the mirror to convert the beam reflected by the second beam splitter into parallel light; And an astigmatism lens disposed between the second photodetector and the second beam splitter to allow spots reflected from the optical disc for BD to form spots on the second photodetector.

In the present invention, since the first objective lens and the first photodetector of the DVD / CD optical system are installed on the same axis, and the first light source is installed on the axis perpendicular to the axis on which the first objective lens and the first photodetector are installed, 0 ° In addition to having a free incidence structure of ˜180 °, the first objective lens and the first photodetector are installed on the same axis, so that the DVD / CD optical system of the conventional optical pickup is installed on the optical path between the objective lens and the photodetector. Astigmatism lenses and mirrors can be removed to reduce the volume of optical pickup and the manufacturing cost of optical pickup.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view showing the optical system configuration of the optical pickup according to an embodiment of the present invention, Figure 4 is a three-dimensional view showing the optical system configuration of the optical pickup shown in FIG.

3 and 4, an optical pickup according to an embodiment of the present invention is a BD for reproducing a DVD / CD optical system 10 for reproducing an optical disc D1 for a DVD / CD and an optical disc D2 for a BD. It consists of an optical system 50.

The DVD / CD optical system 10 includes a first light source 12, a first grating element 14, a first beam splitter 16, a first collimating lens 18, a first objective lens 20, and a first object. It consists of the photodetector 22.

At this time, the first photodetector 22 is a PDIC (Photo Diod Intergrated Circuit) capable of receiving all the light reflected from the optical disc D1 for DVD / CD and returning it to detect an information signal and an error signal. .

In addition, the first objective lens 20 focuses the light emitted from the first light source 12 to be collected at one point (ie, to form a spot) on the optical disc D1 for the DVD / CD, and also to the DVD / CD. The light reflected by the optical disk D1 is converted into parallel light.

In the DVD / CD optical system 10, the first objective lens 20, the first collimating lens 18, and the first photodetector 22 are installed on the same axis as shown in FIG. The light source 12 is installed on an axis perpendicular to the axis on which the first objective lens 20 and the first photodetector 22 are installed.

In other words, when the first light source 12 is installed on the X-axis or the Z-axis in a three-dimensional space consisting of the X-axis, the Y-axis, and the Z-axis, the first objective lens 20 and the first photodetector 22 are Y It is installed on the shaft.

In the DVD / CD optical system 10, the first light source 12 emits light suitable for reproducing the optical disc D1 for DVD / CD, and the first objective lens 20 emits light in the first light source 12. The emitted light is focused to form spots on the optical disc D1 for DVD / CD, and the light reflected by the optical disc D1 for DVD / CD is converted into parallel light.

In addition, the first photodetector 22 is installed on the same axis as the first objective lens 20, detects the light reflected from the optical disc D1 for DVD / CD, converts the optical signal into an electrical signal, and first gratings. The element 14 is installed on the emission side of the first light source 12 (ie, between the first light source 12 and the first beam splitter 16) to diffract the light emitted from the first light source 12 to track Split to form a 3-beam for king signal detection.

In addition, the first beam splitter 16 includes an incident optical path through which light emitted from the first light source 12 is transmitted to the optical disk D1 for DVD / CD, and light reflected by the optical disk D1 for DVD / CD. The first grating element 14 is disposed between the first grating element 14, the first objective lens 20, and the first photodetector 22 where the output light paths transmitted to the photodetector 22 cross each other. The beam split by is transmitted or reflected toward the first objective lens 20 according to the polarization component.

In addition, the first collimating lens 18 is installed between the first objective lens 20 and the first beam splitter 16 to convert the beam reflected by the first beam splitter 16 into parallel light, and the DVD. Reflected light reflected from the optical disk D1 for CD is condensed so as to form a spot in the first photodetector 22 coaxial with the first objective lens 20.

Accordingly, when the first light source 12 emits light having a wavelength suitable for reproducing the optical disc D1 for a DVD / CD, the DVD / CD optical system 10 receives the first light source 12 and the first beam splitter ( The first grating element 14 interposed between the 16 and the second grating element 14 is diffracted so as to diffract the light emitted from the first light source 12 to form a three-beam for tracking signal detection.

In this case, the split beam is transmitted to the first beam splitter 16, which transmits the beam according to the polarization component of the light split by the first grating element 14 or toward the first objective lens 20. Reflect.

The reflected beam reflected toward the first objective lens 20 is converted into parallel light by the first collimating lens 18, and the first objective lens 20 is parallel transmitted from the first collimating lens 18. Light is condensed at one point on the optical disc D1 for DVD / CD.

That is, the first objective lens 20 collects the light emitted from the first light source 12 to form a spot on the optical disc D1 for DVD / CD.

Subsequently, when light is reflected from the optical disc D1 for DVD / CD, the reflected light reflected from the optical disc D1 for DVD / CD by the first objective lens 20 is converted into parallel light, and the first collimating lens 16 ), The parallel light is focused so that a spot is formed in the first photodetector 22 which is coaxial with the first objective lens 20.

Accordingly, the first photodetector 22 converts the optical signal of the collected light into an electrical signal.

The BD optical system 50 includes a second light source 52, a second grating element 54, a second beam splitter 56, a second collimating lens 58, a mirror 60, a mask 62, The second objective lens 64, the astigmatism lens 66, and the second photodetector 68 are comprised.

In the BD optical system 50, the second light source 52 and the second photodetector 68 are installed to be perpendicular to the same plane, and the second objective lens 64 is the second light source 52 and the second light. The detector 68 is installed on an axis perpendicular to the installed axis.

In other words, in the three-dimensional space consisting of the X-axis, the Y-axis, and the Z-axis, the second light source 52 is installed on the X-axis, the second photodetector 68 is installed on the Z-axis, and the second objective lens 64 ) Is installed on the Y axis.

At this time, when the second light source 52 is installed on the Z axis, the second photodetector 68 is installed on the X axis.

The BD optical system 50 emits light having a wavelength suitable for reproducing the optical disc D2 for a BD, that is, the emission side of the second light source 52 (that is, the second light source 52). ) And a second grating element 54 installed between the second beam splitter 56) are diffracted to diffract the light emitted from the second light source 52 to form a three-beam for tracking signal detection.

In this case, the divided beam is transmitted to the second beam splitter 56, which transmits or reflects toward the mirror 60 according to the polarization component of the light split by the second grating element 54.

To this end, the second beam splitter 56 includes an incident optical path through which light emitted from the second light source 52 is transmitted to the optical disc D2 for BD, and the light reflected from the optical disc D2 for BD is transmitted to the second photodetector ( It is provided where the output light path transmitted to 68 intersects, that is, between the second grating element 54, the second collimating lens 58 and the astigmatism lens 66.

The beam reflected by the second beam splitter 56 is converted into parallel light by a second collimating lens 58 provided between the mirror 60 and the second beam splitter 56, and the parallel light is converted into a mirror ( 60 is reflected vertically (90 °) toward the second objective lens 64.

The parallel light reflected by the mirror 60 in the direction of the second objective lens 64 is transmitted to the second objective lens 64 through the mask 62, and the second objective lens 64 moves the mask 62. The light transmitted through this is focused to form spots on the optical disc D2 for BD.

That is, the second objective lens 64 condenses the light emitted from the second light source 52 in one place of the BD optical disk D2.

The reflected light reflected by the optical disc D2 for BD includes the second objective lens 64, the mask 62, the mirror 60, the second collimating lens 58, the second beam splitter 56, and astigmatism. The light is collected by the second photodetector 68 through the lens 66, and the second photodetector 68 condenses the light reflected by the optical disc D2 for BD and converts the light into an electrical signal.

At this time, the astigmatism lens 66 is installed between the second photodetector 68 and the second beam splitter 56 so that the light reflected from the BD optical disk D2 is accurately spotted on the second photodetector 68. Make a decision.

As described above, in the optical pickup according to the exemplary embodiment of the present invention, the first objective lens 20 and the first photodetector 22 of the DVD / CD optical system 10 are disposed on the same axis, and the first light source 12 is made of the optical pickup. Since the first objective lens 20 and the first photodetector 22 are installed on an axis perpendicular to the axis in which the first objective lens 20 and the first photodetector 22 are installed, the first objective lens 20 and the first objective lens 20 and the first objective lens 20 can be freely provided. Since the photodetector 22 is installed on the same axis, the astigmatism lens and the mirror installed on the optical path between the objective lens and the photodetector can be removed in the DVD / CD optical system of the conventional optical pickup. The manufacturing cost can be reduced.

1 is a view showing an optical system configuration of an optical pickup according to the prior art.

FIG. 2 is a stereoscopic view showing the optical system configuration of the optical pickup shown in FIG. 1 in three dimensions.

3 is a diagram illustrating an optical system configuration of an optical pickup according to an exemplary embodiment of the present invention.

FIG. 4 is a stereoscopic view showing the optical system configuration of the optical pickup shown in FIG. 3 in three dimensions.

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

10, 100: DVD / CD optical system 12, 52, 102, 202: light source

14, 54, 104, 204: grating elements 16, 56, 106, 206: beam splitter

18, 58, 108, 208: collimating lens 20, 64, 112, 212: objective lens

22, 68, 116, 216: photodetectors 50, 200: BD optical system

60, 110, 210: Mirror 62, 212: Mask

66, 114, 214: astigmatism lens

Claims (4)

A DVD / CD optical system for playing an optical disc for a DVD / CD; And A BD optical system for playing an optical disc for BD, The DVD / CD optical system, A first light source which emits light for reproduction of the DVD / CD optical disc; A first photodetector installed on an axis perpendicular to the axis on which the first light source is installed to detect reflected light reflected from the optical disc for DVD / CD and convert the reflected light into an electrical signal; Installed on the same axis as the first photodetector to condense the light emitted from the first light source so that the light emitted from the first light source forms a spot on the optical disc for DVD / CD, and in the optical disc for DVD / CD A first objective lens for converting the reflected light into parallel light; A first beam splitter disposed between the first photodetector and the first objective lens and configured to transmit or reflect light emitted from the first light source toward the first objective lens; And A first light splitter disposed between the first beam splitter and the first objective lens to focus the parallel light to form a spot on the first photodetector, and to convert the reflected beam reflected by the first beam splitter into parallel light Optical pickup comprising a collimating lens. The method of claim 1, And a first grating device disposed between the first light source and the first beam splitter to diffract and split light emitted from the first light source. The method of claim 1, The first light source is installed on any one of the X and Z axes in a three-dimensional space consisting of X, Y and Z axes, and the first objective lens and the first photodetector are installed on the Y axis. Optical pickup, characterized in that. The method of claim 2, The BD optical system, A second light source which emits light for reproduction of the BD optical disc; A second photodetector for detecting reflected light reflected from the BD optical disk and converting an optical signal into an electrical signal; A second objective lens for condensing the light emitted from the second light source such that the light emitted from the second light source forms a spot on the optical disc for BD; A mirror that vertically reflects the light emitted from the second light source and transmits the light to the second objective lens; A second grating element installed at an emission side of the second light source and dividing and dividing the light emitted from the second light source; A second beam splitter disposed between the mirror and the second photodetector to transmit or reflect toward the mirror according to the polarization component of the light split by the second grating element; A second collimating lens installed between the second beam splitter and the mirror to convert the beam reflected by the second beam splitter into parallel light; And And an astigmatism lens disposed between the second photodetector and the second beam splitter such that the light reflected from the optical disc for BD forms a spot on the second photodetector.

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