KR100220506B1 - An optical head system using a dual focus method - Google Patents
An optical head system using a dual focus method Download PDFInfo
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- KR100220506B1 KR100220506B1 KR1019950017781A KR19950017781A KR100220506B1 KR 100220506 B1 KR100220506 B1 KR 100220506B1 KR 1019950017781 A KR1019950017781 A KR 1019950017781A KR 19950017781 A KR19950017781 A KR 19950017781A KR 100220506 B1 KR100220506 B1 KR 100220506B1
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- light
- lens
- disk
- grating
- laser diode
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1374—Objective lenses
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0925—Electromechanical actuators for lens positioning
- G11B7/0927—Electromechanical actuators for lens positioning for focusing only
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1353—Diffractive elements, e.g. holograms or gratings
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1372—Lenses
- G11B7/1376—Collimator lenses
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1395—Beam splitters or combiners
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Abstract
본 발명은 듀얼 포커스법에 사용되는 광학헤드장치에 관한 것으로, 레이저광을 방사시키는 레이저 다이오드와, 이 레이저 다이오드로부터 방사된 빛을 그 표면에 형성된 회절격자에 의해 쓰리빔으로 분리하는 그레이팅과, 이 그레이팅을 통해 분리된 쓰리빔을 90로 방향을 바꾸어 반사시키고 디스크로부터 반사되어 되돌아오는 빛은 그대로 투과시키는 빔스플리터와, 이 빔스플리터에 의해 90방향이 바뀐 빛을 평행광으로 변환시키는 콜리메이트렌즈와, 이 콜리메이트렌즈를 통해 입사된 빛을 촛점거리가 서로 다르게 촛점을 형성시키는 이중결합 대물렌즈로 이루어져, 촛점거리가 서로 다른 복수개의 렌즈를 접합시키거나 좌, 우의 촛점거리가 서로 다른 하나의 사출물 대물렌즈를 구성하고 이 구성된 대물렌즈에 의해 디스크 피트에 정확한 촛점을 맞추도록 하므로써, 1.2, 0.6인 2종류의 디스크를 재생하는데 용이하게 실행하게 되므로 이에 따라 시스템의 기능성을 증가시키도록 됨은 물론 디스크 두께에 따른 정확한 촛점거리를 대물렌즈의 이중결합구조에 의해 맞추어지게 되므로 별도의 홀로그램소자가 필요없게 되어 구조가 간단하게 되므로 이에 따라 제조비용도 상당히 감소시킬 수 있다.The present invention relates to an optical head device used in the dual focus method, comprising: a laser diode that emits laser light, a grating for separating the light emitted from the laser diode into a three beam by a diffraction grating formed on the surface thereof; Three beams separated by grating The beam splitter which changes the direction of the furnace and reflects it, and transmits the light reflected back from the disk as it is. It consists of a collimated lens that converts the changed light into parallel light and a double-coupled objective lens that focuses the light incident through the collimated lens with different focal lengths. By combining or constructing one injection objective with different focal lengths at the left and right and allowing the target to be precisely focused on the disc pit, 1.2 , 0.6 This makes it easy to play two types of discs, thereby increasing the functionality of the system. The exact focus distance according to the disc thickness is set by the double coupling structure of the objective lens, eliminating the need for a separate hologram element. As a result, the structure can be simplified, so that the manufacturing cost can be significantly reduced.
Description
제1도는 종래 광학헤드장치를 설명하는 설명도이고,1 is an explanatory diagram for explaining a conventional optical head device,
제2도는 본 발명 광학헤드장치를 설명하는 설명도이다.2 is an explanatory diagram for explaining the optical head device of the present invention.
* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings
1 : 레이저 다이오드 2 : 그레이팅1: laser diode 2: grating
3 : 빔스플리터 4 : 콜리메이트렌즈3: beam splitter 4: collimated lens
5 : 이중결합 대물렌즈 6 : 포토다이오드5: double-coupled objective lens 6: photodiode
7 : 1.2디스크 7 : 제1렌즈부7: 1.2 Disc 7: first lens unit
9 : 0.6디스크 10 : 제2렌즈부9: 0.6 Disc 10: second lens unit
11 : 회절격자11: diffraction grating
본 발명은 듀얼 포커스법에 사용되는 광학헤드장치에 관한 것으로, 특히 촛점거리에 서로 다른 복수개의 렌즈를 형성시킨 이중결합 구조의 대물렌즈를 구성하고, 이 구성된 대물렌즈에 의해 1.2, 0.6인 2종류의 디스크를 호환 재생이 가능하여 제조비용도 상당히 감소시킬 수 있는 듀얼 포커스법에 사용되는 광학헤드장치에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used in a dual focusing method, and in particular, to construct an objective lens having a double coupling structure in which a plurality of lenses having different focal lengths are formed. , 0.6 The present invention relates to an optical head device used in the dual focus method capable of compatible playback of two kinds of disks, which can significantly reduce manufacturing costs.
일반적으로 듀얼 포커스법에 사용되는 광학헤드장치는 제1도에 도시된 바와 같이 레이저광을 방사시키는 레이저 다이오드(70)와, 이 레이저 다이오드(70)로부터 방사된 빛을 90로 방향을 바꾸어 반사시키고 디스크로부터 반사되는 빛은 그대로 투과시키는 빔스플리터(71)와, 이 빔스플리터(71)에 의해 90로 방향이 바뀐 레이저 다이오드(70)의 방사된 빛을 평행광으로 변환시키는 콜리메이트 렌즈(72)와, 이 콜리메이트 렌즈(72)의 평행광을 회절시키는 홀로그램소자(73)와, 이 홀로그램소자(73)로부터 입사되는 빛을 디스크상에 촛점을 맺히게 하는 대물렌즈(74)로 이루어져 있다.In general, the optical head device used in the dual focus method includes a laser diode 70 that emits laser light as shown in FIG. 1, and the light emitted from the laser diode 70. The beam splitter 71 which changes the direction of the furnace and reflects the light reflected from the disk and transmits the light as it is, and the beam splitter 71 A collimating lens 72 for converting the emitted light of the laser diode 70 whose direction is changed into parallel light, a hologram element 73 for diffracting parallel light of the collimating lens 72, and the hologram element It consists of an objective lens 74 for focusing light incident from 73 on the disk.
또한, 상기 홀로그램소자(73)는 그 몸체 평면 중심부분에 홀로그램격자(75)가 형성되어 있다.In the hologram element 73, a hologram grid 75 is formed at the central portion of the body plane.
한편, 상기와 같이 구성된 종래 광학헤드장치의 작용을 살펴보면, 먼저, 듀얼 포커스법으로 동작되는 데크에 디스크가 장착되면, 예컨대, 1.2() 디스크(76)가 장착되어 재생될 경우 레이저 다이오드(70)에서 레이저광이 빔스플리터(71)로 방사되게 된다. 그러면, 이 방사된 레이저광은 빔스플리터(71)에 의해 90로 방향이 바뀌어져 콜리메이트 렌즈(72)로 입사되게 되고 그 입사된 빛은 콜리메이트 렌즈(72)에 의해 평행광으로 변환되어 홀로그램소자(73)를 통과하고 이 통과된 빛은 대물렌즈(74)에 의해 1.2()의 디스크(76)의 피트에 촛점이 맺혀지게 된다.On the other hand, looking at the operation of the conventional optical head device configured as described above, first, when the disk is mounted on the deck operated by the dual focus method, for example, When the disk 76 is mounted and reproduced, the laser light is emitted from the laser diode 70 to the beam splitter 71. Then, this emitted laser light is transmitted by the beam splitter 71 to 90 degrees. Direction is changed to enter the collimating lens 72, and the incident light is converted into parallel light by the collimating lens 72 and passes through the hologram element 73, and the light passed through the objective lens 74 1.2 by Is focused on the pit of the disk 76.
이때, 상기 대물렌즈(74)로 입사되는 홀로그램소자(73)의 빛중 홀로그램격자(75)에 의해 회절된 1차 회절빛(The 1st order diffracted light)만이 유효하게 ±1.2() 디스크(76)의 피트에 정확히 촛점이 맺히게 된다. 또한 이 디스크(76)에 의해 반사된 빛은 입사되는 역순으로 반사되어 빔스플리터(71)로 입사되게 된다. 그러면, 이 빔스플리터(71)로 입사된 빛은 이 빔스플리터(71)로 투과하여 포토다이오드(77)로 수광되게 되어 정보재생 그리고 포커스 및 트래킹 제어기능을 수행하게 된다.At this time, only the first order diffracted light diffracted by the hologram lattice 75 of the hologram element 73 incident on the objective lens 74 is effectively ± 1.2 ( The focus is precisely on the pit of the disk 76. In addition, the light reflected by the disk 76 is reflected in the reverse order of incidence and enters the beam splitter 71. Then, the light incident on the beam splitter 71 passes through the beam splitter 71 and is received by the photodiode 77 to perform information reproduction and focus and tracking control functions.
그런데, 만약 상기 과정 중에 상기 데크에 0.6()의 디스크(78)가 장착되었다면 상기 홀로그램소자(73)를 통과하는 빛 중 홀로그램격자(75) 형성 부분을 제외한 나머지 부분을 통과하는 0차 회절빛(The 0's order diffracted light)만이 유효하게 되어 대물렌즈(74)를 통해 0.6() 디스크(78)의 피트에 정확히 촛점이 맺히게 된다. 따라서, 상기 1.2() 디스크(76)의 재생동작에서와 같이 동작되어 통상의 정보재생 기능을 수행하게 된다.However, if the deck is in the process of 0.6 ( If the disk 78 is mounted, only the 0's order diffracted light passing through the remaining portion except for the hologram grid 75 forming portion of the light passing through the hologram element 73 becomes effective. 0.6 through lens 74 The focus is precisely on the pit of the disk 78. Therefore, above 1.2 ( The same operation as in the reproducing operation of the disk 76 is performed to perform a normal information reproducing function.
그러나, 상기와 같이 종래 듀얼 포커스법에 사용되는 광학헤드장치는 2중 포커스를 형성하는 홀로그램소자(73)의 제작이 매우 어렵기 때문에 그로 인해 제조비용이 상당히 증가되는 결점이 있었다.However, as described above, the optical head device used in the conventional dual focus method has a drawback in that the manufacturing cost is significantly increased because the manufacturing of the hologram element 73 forming the double focus is very difficult.
이에 본 발명은 상기와 같은 제반결점을 해결하기 위해 안출된 것으로, 촛점거리가 서로 다른 복수개의 렌즈를 접합시켜 이중결합구조의 대물렌즈를 구성하고, 이 구성된 대물렌즈에 의해 디스크 두께에 관계없이 정보재생 동작을 용이하게 실행하게 되므로 이에 따라 시스템의 기능성을 증가시키도록 됨은 물론 디스크 두께에 따른 정확한 촛점거리를 대물렌즈의 이중결합구조에 의해 맞추어지게 되므로 별도의 홀로그램소자가 필요없게 되어 구조가 간단하게 되므로 이에 따라 제조비용도 상당히 감소시킬 수 있는 듀얼 포커스법에 사용되는 광학헤드장치를 제공함에 그 목적이 있다.Accordingly, the present invention has been made to solve the above-mentioned shortcomings, and a plurality of lenses having different focal lengths are joined to form an objective lens having a double coupling structure, and the objective lens is configured to provide information regardless of the thickness of the disk. As the reproducing operation is easily performed, the system functionality is increased accordingly, and the exact focal length according to the disk thickness is adjusted by the double coupling structure of the objective lens, thus eliminating the need for a separate hologram element. Therefore, it is an object of the present invention to provide an optical head device used in the dual focus method that can significantly reduce the manufacturing cost accordingly.
상기와 같은 목적을 달성하기 위한 본 발명은, 레이저광을 방사시키는 레이저 다이오드와, 이 레이저 다이오드로부터 방사된 빛을 그 표면에 형성된 회절격자에 의해 쓰리빔으로 분리하는 그레이팅과, 이 그레이팅을 통해 분리된 쓰리빔을 90로 방향을 바꾸어 반사시키고 디스크로부터 반사되어 되돌아오는 빛은 그대로 투과시키는 빔스플리터와, 이 빔스플리터에 의해 90방향이 바뀐 빛을 평행광으로 변환시키는 콜리메이트렌즈와, 이 콜리메이트렌즈를 통해 입사된 빛을 상이한 두께의 디스크상에 각각 촛점을 형성시키도록 렌즈의 곡률이 상이한 제1렌즈부와 제2렌즈부가 양측에서 성형된 이중결합 대물렌즈를 포함하여 이루어진 듀얼 포커스법에 사용되는 광학헤드장치를 제공한다.The present invention for achieving the above object, a laser diode for emitting a laser light, grating for separating the light emitted from the laser diode into a three beam by a diffraction grating formed on its surface, and separating through this grating Three Beams 90 The beam splitter which changes the direction of the furnace and reflects it, and transmits the light reflected back from the disk as it is. A collimating lens for converting the changed light into parallel light, and a first lens unit and a second lens having different curvatures so as to focus the light incident through the collimating lens on discs having different thicknesses; Provided are an optical head device for use in a dual focus method including a double-bond objective lens molded at both sides.
이하, 본 발명을 첨부된 예시 도면에 의거 상세히 설명한다.Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
본 발명 장치는 제2도에 도시된 바와 같이 레이저광을 방사시키는 레이저 다이오드(1)와, 이 레이저 다이오드(1)로부터 방사된 빛을 제1도에 도시된 바와 같은 파형의 쓰리빔으로 분리하는 그레이팅(2)과, 이 그레이팅(2)을 통해 분리된 쓰리빔 즉, O차광(The O's order diffraction light)과 ±1차광(The 1st order diffraction light)을 90로 방향을 바꾸어 반사시키고 디스크로부터 반사되는 빛은 그대로 투과시키는 빔스플리터(3)와, 이 빔스플리터(3)에 의해 90로 방향이 바뀐 빛을 평행광으로 변환시키는 콜리메이트렌즈(4)와, 이 콜리메이트렌즈(4)를 통해 입사된 빛이 이중렌즈 결합구조에 의해 서로 다른 촛점을 형성시키는 이중결합 대물렌즈(5) 및, 이 이중결합 대물렌즈(5)와 빔스플리터(3)를 거쳐 디스크에서 반사되어 되돌아오는 광정보를 전류로 변환하는 포토다이오드(6)로 이루어진다.The apparatus of the present invention separates a laser diode 1 that emits laser light as shown in FIG. 2 and a three beam of wave form as shown in FIG. 1 from the light emitted from the laser diode 1. Grating (2), and the three beams separated by the grating (2), i.e., the O's order diffraction light and the 1st order diffraction light. The beam splitter 3 which changes the direction of the furnace and reflects the light reflected from the disk and transmits the light as it is, and the beam splitter 3 A collimated lens 4 for converting the light converted into a parallel light into parallel light, and a double-coupled objective lens in which light incident through the collimated lens 4 forms a different focus by a double lens coupling structure (5). And a photodiode 6 for converting the optical information reflected from the disk through the double-coupled objective lens 5 and the beam splitter 3 into an electric current.
여기서, 상기 이중결합 대물렌즈(5)는 촛점거리가 서로 다르게 하기 위하여 같은 재질 즉, 동일한 재질로 된 단일 렌즈에서 그 곡률이 상이하도록 성형된 제1 및 제2렌즈부(8,10)를 형성하므로 개구수가 상이하게 되는 렌즈를 하나의 사출물로 성형하여 대물렌즈를 구성하게 된다.In this case, the double-coupled objective lens 5 forms the first and second lens portions 8 and 10 formed to have different curvatures in a single lens made of the same material, that is, the same material, so that the focal length is different from each other. Therefore, the objective lens is formed by molding a lens having a different numerical aperture into one injection molded product.
한편, 본 실시예에서는 이와 같이 양측의 곡률이 상이한 렌즈가 채택된 실시예를 제2도에 도시하였고, 이에 따라 상기와 같은 구성된 본 발명의 작용·효과를 설명한다.On the other hand, in the present embodiment, an embodiment in which lenses having different curvatures on both sides are adopted is shown in FIG. 2, and thus the operation and effect of the present invention configured as described above will be described.
먼저, 디스크가 장착되고 재생기능이 설정되게 되면 레이저 다이오드(1)에서 레이저광이 그레이팅(2)으로 방사되게 된다. 그러면 이 방사된 레이저광이 그레이팅 표면에 형성된 회절격자(11)를 통과하여 빔스플리터(3)로 입사되게 되는데, 이때, 이 통과되는 빛은 0차, ±1차광의 쓰리빔으로 분리되어 입사되게 된다.First, when the disc is loaded and the regeneration function is set, the laser light is emitted from the laser diode 1 to the grating 2. Then, the emitted laser light passes through the diffraction grating 11 formed on the grating surface and is incident on the beam splitter 3, wherein the light passing through the beam is split into three beams of 0 order and ± 1 order light. do.
그리고, 이 빔스플리터(3)에서 상기 쓰리빔을 90로 방향을 바꾸어 콜리메이트렌즈(4)로 입사시키게 되고 그 입사된 빛은 콜리메이트렌즈(4)에 의해 평행광으로 변환되어 이중결합 대물렌즈(5)로 입사되게 된다. 그리고 이 입사된 빛은 이중결합 대물렌즈(5)에 의해 디스크(7,9)의 피트에 촛점이 맺혀지게 되는데, 이때, 이 빛은 제1렌즈부(8)와 제2렌즈부(10)로 입사되게 된다.The beam splitter 3 then uses the three beams 90 The direction of the furnace is changed to enter the collimated lens 4, and the incident light is converted into parallel light by the collimated lens 4 to be incident on the double coupled objective 5. The incident light is focused on the pit of the disks 7 and 9 by the double-coupled objective lens 5, wherein the light is focused on the first lens unit 8 and the second lens unit 10. To be incident.
그러면, 각각의 렌즈부(8,10)가 그 곡률의 상이함으로 인하여 제1렌즈부(8)로 입사되는 빛은 비교적 긴 촛점거리를 가지게 되고 이에비해 제2렌즈부(10)로 입사되는 빛은 비교적 짧은 촛점거리를 가지게 된다.Then, the light incident on the first lens unit 8 has a relatively long focal length due to the difference in curvature of the respective lens units 8 and 10, whereas the light incident on the second lens unit 10 is compared. Has a relatively short focal length.
따라서, 데크에 장착되는 디스크의 종류에 관계없이 정보재생동작을 실행하게 되는데, 예를 들어 데크에 1.2크기의 디스크(7)가 장착되면 제1렌즈부(8)에 의해 이 디스크(7)의 피트에 촛점이 맺혀지게 되고, 만약 0.6크기의 디스크(9)라면 제2렌즈부(10)에 의해 촛점이 맺혀지게 된다.Therefore, the information reproducing operation is executed regardless of the type of the disc mounted on the deck. When a disc 7 of size is mounted, the first lens unit 8 focuses on the pit of the disc 7, and if 0.6 If the disk 9 is the size, the focus is formed by the second lens unit 10.
한편, 상기와 같이 디스크(7,9)들에 입사된 빔은 이 디스크(7,9)로부터 반사되어 광정보를 포함한 채 대물렌즈(5)와 빔스플리터(3)를 거쳐 포토다이오드(6)로 수광되는데, 이때, 쓰리빔 중 0차광은 디스크(7,9)의 촛점을 형성하는데 대부분 사용되고 나머지 ±1차광은 포토다이오드(6)의 F나 E셀로 수광되게 된다. 그리고, 이 포토다이오드(6)는 이 입사된 광정보를 전류로 변환하여 정보재생기능과, 포커스기능 및 트래킹 기능을 수행하게 된다.On the other hand, the beams incident on the disks 7 and 9 are reflected from the disks 7 and 9 as described above, and the photodiode 6 passes through the objective lens 5 and the beam splitter 3 while including the optical information. In this case, the 0th order light among the three beams is mostly used to form the focus of the disks 7 and 9, and the remaining ± 1st order light is received by the F or E cells of the photodiode 6. The photodiode 6 converts the incident optical information into a current to perform an information reproducing function, a focusing function and a tracking function.
이상 설명에서와 같이 본 발명은 촛점거리가 서로 다른 복수개의 렌즈를 형성하여 이중결합구조의 대물렌즈를 구성하고 이 구성된 대물렌즈에 의해 디스크 피트에 정확한 촛점을 맞추도록 하므로써, 1.2, 0.6인 2종류의 디스크를 재생하는데 용이하게 실행하게 되므로 상이한 디스크 두께에 따라 대물렌즈의 이중결합구조에 의해 정확한 촛점이 맞추어지게 되므로 별도의 홀로그램소자가 필요없게 되어 구조가 간단하게 되므로 이에 따라 제조비용도 상당히 감소시킬 수 있는 효과가 있다.As described above, the present invention forms a plurality of lenses having different focal lengths to form an objective lens having a double coupling structure, and by using the configured objective lens to precisely focus on the disc pit, 1.2 , 0.6 Since two types of discs can be easily reproduced, precise focusing is achieved by the double coupling structure of the objective lens according to different disc thicknesses. Therefore, a separate hologram element is not required, so the structure is simplified, thus the manufacturing cost is also increased. There is an effect that can be significantly reduced.
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Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019950017781A KR100220506B1 (en) | 1995-06-28 | 1995-06-28 | An optical head system using a dual focus method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019950017781A KR100220506B1 (en) | 1995-06-28 | 1995-06-28 | An optical head system using a dual focus method |
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| Publication Number | Publication Date |
|---|---|
| KR970002953A KR970002953A (en) | 1997-01-28 |
| KR100220506B1 true KR100220506B1 (en) | 1999-09-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| KR1019950017781A KR100220506B1 (en) | 1995-06-28 | 1995-06-28 | An optical head system using a dual focus method |
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| KR (1) | KR100220506B1 (en) |
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1995
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| KR970002953A (en) | 1997-01-28 |
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