KR970060087A

KR970060087A - An optical pickup device using a liquid crystal plate

Info

Publication number: KR970060087A
Application number: KR1019960000928A
Authority: KR
Inventors: 오평희; 이명숙
Original assignee: 오평희
Priority date: 1996-01-09
Filing date: 1996-01-09
Publication date: 1997-08-12

Abstract

본 발명은 액정판(6)을 써서 광속의 크기(Beam Size)를 조절하는 광픽업(Optical Pick Up)장치에 관한 것이다. 종래의 액정판(6)을 쓴 광학계에서는 편광판을 써서 레이저다이오드(1)에서 나온 빛을 투과 또는 흡수시키는 액정표시형을 썼기 때문에 두께가 균일한 결정형 관광판을 써야 하므로 비용이 매우 크다. 그래서 액정층(32)에 이방성 염료를 넣어 빛을 흡수하고 투과하는 GH형(Gust Host Mode)을 써서 편광판(9)을 쓰지 않는 방법이 제기되었지만, 빛의 투과율과 명암대비율이 낮아서 빛의 세기가 큰 광원을 써야 되고 검출기에서 나온 신호의 해석이 어려워 실용화가 되지 않았다. 또한 액정배열을 이용한 액정홀로그램방식으로 편광판(9)을 대신 하는 방식도 나왔지만 선폭이 0.5㎛ 이하이기 때문에 생산성이 떨어졌다. 본 발명에서는 레이저다이오드(1)에서 나온 빛이 편광광속분할기(3)를 지나, 반사형 액정판(6)에서 반사되어 편광광속분할기(3)에 되돌아가게하고, 반사형 액정판(6)에서 액정분자배열을 변화시켜 편광상태가 달라진 부분만이 편광속분할기(3)에서 반사되어 광기억소자(8)쪽으로 조사되게하여 광속의 크기를 조절하여 유전체 박막을 10층정도 입히는 비용만으로 광속의 크기를 조절할 수 있게 하였다. 또한 편광광속분할기(3)와 사반파장판을 써서 레이저다이오드(1)의 출력을 종래에 비하여 1/4만 되어도 광검출을 할 수 있는 광검출장치를 발명하였다.The present invention relates to an optical pick-up apparatus for adjusting a beam size by using a liquid crystal plate (6). In the optical system using the conventional liquid crystal plate 6, since a liquid crystal display type which transmits or absorbs the light emitted from the laser diode 1 by using a polarizing plate is used, the cost is very high because a crystalline type tourist plate having a uniform thickness is used. Thus, a method of not using the polarizing plate 9 by using a GH type (Gust Host Mode) in which anisotropic dye is put in the liquid crystal layer 32 to absorb and transmit light is proposed. However, since the transmittance of light and the contrast ratio are low, A large light source has to be used and it is difficult to interpret the signal from the detector and it has not been practically used. In addition, although a method of replacing the polarizing plate 9 with a liquid crystal hologram system using a liquid crystal array has been proposed, the productivity is lowered because the line width is 0.5 탆 or less. The light emitted from the laser diode 1 passes through the polarized beam splitter 3 and is reflected by the reflection type liquid crystal plate 6 to be returned to the polarized beam splitter 3 and reflected from the reflection type liquid crystal plate 6 Only the portion where the polarization state is changed by changing the arrangement of the liquid crystal molecules is reflected by the polarization beam splitter 3 to be irradiated toward the optical storage element 8 to adjust the size of the light flux so that the size of the light flux . In addition, a photodetector capable of detecting light even if the output of the laser diode 1 is 1/4 of that of the conventional one by using the polarized light beam splitter 3 and the quadrupole wave plate.

본 발명의 액정판(6)을 쓴 광픽업장치는 CD를 읽을 수 있는 DVD(Digital Viedo Disk)의 광픽업장치등에 쓰일 수 있다.The optical pickup device using the liquid crystal plate 6 of the present invention can be used for an optical pickup device of a DVD (Digital Viedo Disk) that can read CDs.

Description

An optical pickup device using a liquid crystal plate

본 내용은 요부공개 건이므로 전문내용을 수록하지 않았음Since this is a trivial issue, I did not include the contents of the text.

제1도는 액정판을 쓴 종래의 광픽업장치.Fig. 1 shows a conventional optical pickup apparatus using a liquid crystal plate.

제2도는 액정판을 쓴 본 발명의 광픽업장치의 한 예.FIG. 2 is an example of an optical pickup device of the present invention using a liquid crystal plate.

제3도는 액정판을 쓴 본 발명의 광픽업장치의 한 예.3 is an example of an optical pickup device of the present invention using a liquid crystal plate.

Claims

The light emitted from the laser diode 1 passes through the polarized light beam splitter 3 and is reflected by the reflection type liquid crystal plate 6 to be returned to the polarized light beam splitter 3, So that only the portion where the polarization state is changed is reflected by the flat beam divider 3 to be irradiated toward the optical storage element 8 to adjust the size of the light flux.

The liquid crystal display device according to claim 1, wherein the electrode of the lower substrate (31) of the reflection type liquid crystal plate (6) is a reflective electrode of aluminum or silver or chromium film, Polarized light is modulated only in an electrode portion for applying a voltage to the optical pickup device.

The liquid crystal display device according to claim 1, wherein the display type of the liquid crystal is an ECB type having a parallel orientation and the product of the refractive index anisotropy (? N) of the liquid crystal and the thickness (d) of the liquid crystal layer (32) / 4.

The light emitted from the laser diode 1 passes through the polarized light beam splitter 3 and is reflected by the reflecting plate through the half wave plate to be returned to the polarized light beam splitter 3 and reflected by the polarized light beam splitter 3, ) To read the information recorded in the optical storage element (8).

※ Note: It is disclosed by the contents of the first application.