CN1140300A

CN1140300A - Optic pick-up

Info

Publication number: CN1140300A
Application number: CN96106129A
Authority: CN
Inventors: 长冈由起; 中村裕行; 村田道子
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1995-04-17
Filing date: 1996-04-17
Publication date: 1997-01-15
Anticipated expiration: 2016-04-17
Also published as: CN1087859C; KR100297527B1; SG71677A1; TW311221B; KR960038783A; JP3163939B2; JPH08287509A

Abstract

Disclosed is an optical pick-up device, comprising a hololaser unit which can generate divided beams, with the diffraction direction of the diffraction grating consistent with the direction of the outer short edge of the hololaser unit, a pedestal assembled with respect to the hololaser unit in a manner which enables the pedestal to rotate with the optic axis as the center, a reflector which is fixed on the pedestal and vertically reflects the beams from the hololaser unit to the face of a disk, and a field lens arranged between the reflector and the disk. The hololaser unit and the reflector are arranged between the pedestal, with the hololaser unit directing towards the beams from the reflector, so that the angle between the tangent of the projection of the optic axis to the face of the disk and tangent of the projection of the main beam on the face of the disk is at the estimated value.

Description

Optical take-up apparatus

The present invention relates to be used for the optical take-up apparatus of optical disc recording/reproduction device.

Small-sized along with optical disc apparatus in recent years, cost degradation carry out integratedly to the optics of optical take-up apparatus, and use the hologram laser unit that is made of semiconductor laser, light activated element and optical element one.

The optical take-up apparatus of one routine prior art is described with reference to the accompanying drawings.

Fig. 4 represents that the optics of prior art optical take-up apparatus constitutes.Among this figure, 21 for having the hologram laser unit of diffractive grating member 22, and diffractive grating member 22 constitutes by producing the diffraction grating of tracking detection with divided beams; 23 is lens; 24 is object lens; 25 is CD; 26 is the session on the CD; 27 is main beam; 27a, 27b use divided beams for following the tracks of to detect.For the optical take-up apparatus slimming, the profile of hologram laser unit 21 makes rectangle, and the limit with circular arc 28a, the 28b that can do local rotation adjustment is long limit, and all the other are minor face.

Be parallel to the catoptron 23 of light beam B (its optical axis is A) that cd side penetrates vertically to CD reflection by hologram laser unit 21 through having 45 with respect to cd side, and by object lens 24 optically focused to CD.

Fig. 5 is the planimetric map of Fig. 4, and is in Fig. 5, consistent with the tangential direction 29 of the session in main beam incident point from the direction of hologram laser unit 21 toward mirror 23 beam optical axis A.And the angle theta of the line 27c (straight line) of divided beams 27a, 27b and session tangent line 29, when the divided beams spacing is L, when track pitch was P, this angle θ was:

θ＝arcsin(P/2L)

Usually, can optical axis A be that hologram laser unit 21 is adjusted in the center rotation, make to follow the tracks of the detection sensitivity maximum.

Yet, as shown in Figure 6, in using hologram laser unit 21 under the diffraction direction 30 of the diffractive grating member 22 the sort of hologram laser unit situation parallel with the direction of unit 21 profile minor faces 31, in order to make divided beams direction 27c and the above-mentioned θ of session tangential direction 29 inclinations angle, as shown in Figure 7, will make hologram laser unit 21 opposing parallel adjust a α angle, thereby the thickness of optical take-up apparatus 33 increase the section H that hologram laser unit 21 stretches out with respect to optical substrate 32 in the face rotation of CD 25.

In order to alleviate the problems referred to above, as shown in Figure 8, can adopt and make diffractive grating member 22 with respect to tilt the in advance means of predetermined angular of the shell of hologram laser unit 21, but the numerical value that above-mentioned L numerical value is the θ angle is different because of user side object lens multiplying power parameter, so strictly speaking, hologram laser unit 21 can stretch out.

The present invention is characterized in that providing a kind of slim optical take-up apparatus in view of the problem that above-mentioned prior art exists.

Have in order to the optical take-up apparatus of the present invention that solves above-mentioned problem: be used to produce the diffraction direction hologram laser unit consistent that tracking detects the diffraction grating of using divided beams with the shell short side direction; It can be the pedestal of center rotation with its optical axis that this hologram laser unit is mounted to.Be installed on the said base and with above-mentioned hologram laser unit emitted light beams and vertical catoptron to the cd side reflection; Be configured in the object lens between this catoptron and the cd side.Above-mentioned hologram laser unit and above-mentioned catoptron are installed on the described pedestal, make that the angle of the session tangential direction at place, main beam incident point has predetermined value on the direction of optical axis direction cd side projection of light beam of the above-mentioned catoptron of above-mentioned hologram laser unit directive and the CD.

Optical take-up apparatus of the present invention, its above-mentioned hologram laser unit and above-mentioned catoptron are installed on the said base in the following manner, make that the divided beams spacing is L, when track pitch was P, optical axis angle theta of session tangential direction to the projection of cd side and the CD of pointing to the light beam of above-mentioned catoptron from hologram laser unit was:

θ＝arcsin(P/2L)

The present invention disposes hologram laser unit to such an extent that make its optical axis be parallel to cd side by above-mentioned formation, if to its trace adjust just can make and corresponding two divided beams of CD session between straight line by predetermined angle incline, thereby the slimming of realization optical take-up apparatus.

Describe embodiments of the invention with reference to the accompanying drawings in detail.

Fig. 1 is the oblique view of the optical system of optical take-up apparatus of the present invention.

Fig. 2 is the planimetric map of above-mentioned optical system.

Fig. 3 is the outboard profile of this optical take-up apparatus;

Fig. 4 is the oblique view of the optical system of prior art example optical take-up apparatus;

Fig. 5 is the planimetric map of Fig. 4 optical system;

Fig. 6 is the front elevation that is used for the hologram laser unit of existing example;

Fig. 7 is the side view of optical take-up apparatus in the existing example;

Fig. 8 is the front elevation of hologram laser unit in the existing example.

Describe optical take-up apparatus embodiment of the present invention in detail below with reference to Fig. 1-Fig. 3.

Fig. 1 is the three-dimensional view of the optical system of optical take-up apparatus in the embodiment of the invention, and Fig. 2 is the top view of Fig. 1, and Fig. 3 is the side view of optical take-up apparatus.

Among Fig. 1,1 for having the hologram laser unit of diffractive grating member 2, and this diffractive grating member 2 forms to produce follows the tracks of the diffraction grating that detects with divided beams.Hologram laser unit 1 inside has light-emitting component and photo detector (photosensitive device).3 is the catoptron with light beam B (its optical axis 10) the vertical direction reflection of above-mentioned hologram laser unit 1.4 is the object lens to this light beam B optically focused.5 is the CD of the light beam irradiates behind the optically focused.6 is the session on this CD 5.7 main beams that are above-mentioned light beam B optically focused to the CD 5,7a, 7b are for following the tracks of the divided beams that detects usefulness, and 7c is for connecting the straight line of divided beams 7a, 7b.11 is the tangential direction of above-mentioned session 6.In order to make the optical take-up apparatus slimming, it is the rectangle of minor face 8 for long limit opposite side that the shell shape of hologram laser unit 1 makes a side, and the diffraction direction of above-mentioned hologram laser unit 1 is parallel to the direction (vertical direction) of minor face 8.Hologram laser unit 1 has circular arc 9a, the 9b of this hologram laser unit 1 of rotatable adjustment in the direction of minor face 8, when this unit installs on the pedestal 12 that constitutes optical take-up apparatus 13, as adjusting targeting part.

Here, hologram laser unit 1 is installed like that according to making its optical axis 10 directions be parallel to 5 of CDs.Then, as shown in Figure 2, in the plane that is parallel to CD 5, when the angle of the tangential direction 11 of projection 10a from the optical axis 10 of hologram laser unit 1 directional mirror 3 to cd side and session 6 is θ, divided beams 7a, 7b spacing are L, when track pitch (not shown) is P, above-mentioned hologram laser unit 1 and catoptron 3 are installed on the pedestal 12 of optical take-up apparatus according to following relational expression:

θ=arcsin (P/2L) and, θ can be expressed as the parallel lines 11a of session 6 tangent lines and the angle between the optical axis 10 among Fig. 1, it equates with θ angle among above-mentioned Fig. 2.

The following describes the effect of the optical take-up apparatus that as above constitutes.Among Fig. 1, Fig. 2, the light that is parallel to CD 5 surface emitting from hologram laser unit 1, is concentrated on the CD 5 by object lens 4 to the reflection of CD 5 vertical direction by the catoptron 3 that CD 5 surfaces is 45 behind diffraction grating unit 2 diffraction.At this moment, the diffraction direction on CD 5, i.e. the line 7c of divided beams 7a, 7b, consistent with the optical axis 10 of the light beam of hologram laser unit 1 directional mirror 3 to the projection 10a of 5 of CDs.That is, connect the tangential direction 11 formation angle θs of the straight line 7c of divided beams 7a, 7b with respect to session 6, this state can make follows the tracks of the detection sensitivity maximum.

According to above-mentioned present embodiment, because in fact each parts exists error, so need on circular arc 9a, 9b, the shell of hologram laser unit 1 to be done rotation adjustment slightly, but compared with the prior art, can keep hologram laser unit 1 to be parallel to 5 of CDs basically, therefore, in Fig. 3, do not exist from pedestal 12 stretching out outward.

Claims

1. optical take-up apparatus, it is characterized in that, have the diffraction direction hologram laser unit consistent that produces the diffraction grating that divided beams uses with the shell short side direction, it can be the pedestal of center rotation with its optical axis that above-mentioned hologram laser unit is mounted to, be fixed in said base and with above-mentioned hologram laser unit emitted light beams vertically to the catoptron of cd side reflection, and be configured in object lens between this catoptron and the cd side;

Above-mentioned hologram laser unit and above-mentioned catoptron are installed on said base, make the light beam that points to above-mentioned catoptron from above-mentioned hologram laser unit, the angle of its optical axis session tangential direction at main beam subpoint place to the projection of cd side and the cd side has predetermined value.

2. optical take-up apparatus as claimed in claim 1, it is characterized in that, above-mentioned hologram laser unit and above-mentioned catoptron are installed on above-mentioned optical substrate, make that the divided beams spacing is L, point to the light beam of above-mentioned catoptron when track pitch is P from hologram laser unit, the angle of its optical axis session tangential direction at main beam subpoint place to the projection of cd side and the CD satisfies following formula:

θ＝arcsin(P/2L)。