JPH0462133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical pickup in a reproducing apparatus that projects a light spot onto a disk-shaped recording medium to optically read information.

Conventional configuration and its problems In general, in this type of playback device, in order to read information accurately, it is necessary to maximize the performance of the objective lens and narrow down the light spot as small as possible. The optical axis of the objective lens and the disk surface must be perpendicular.

The conventional optical pickup will be explained below. Figure 1 shows the conventional optical pickup, in which 1 is an objective lens, 2 is an objective lens drive device,
3 is an optical block; 4a, 4b, 4c, and 4d are coil springs that are inserted between the objective lens drive device 2 and the optical block 3 and hold the objective lens drive device 1; and 5a, 5b, 5c, and 5d are the coil springs that are inserted between the objective lens drive device 2 and the optical block 3; A screw hole 6 provided at the bottom of the lens drive device 2
a, 6b, 6c, 6d are screw holes 5a, 5b, 5
c, 5d, and coil springs 4a, 4b,
These are screws that compress 4c and 4d.

FIG. 2 is a schematic cross-sectional view to show the drawbacks of the conventional optical pickup, in which 7a and 7b are the centers of the objective lenses, 8a and 8b are the respective optical axes, and 9
a and 9b are respective light spots.

In this conventional configuration, when the tilt of the objective lens 1 is adjusted by turning two of the four screws in FIG. 1, the center 7a of the objective lens moves to 7b as shown in FIG. At the same time, the optical axis moves from 8a to 8b, and the position of the light spot also changes from 8a to 8b.
There is a drawback that the distance between the disk and the objective lens 1 changes as the lens moves from a to 9b. In order to correct this, the change in the distance between the disk and the objective lens 1 is adjusted using the four screws 4a, 4b, 4c, 4
Readjust by turning all d by the same amount,
Further, it was necessary to readjust the change in the position of the light spot by moving and adjusting the entire optical pickup. For this reason, there was a problem in that extra effort was required to adjust the inclination of the objective lens.

Purpose of the Invention The present invention solves the above-mentioned conventional problems. It is possible to easily and quickly adjust the inclination of the optical axis of the objective lens, to narrow down the light spot on the disk, and to An object of the present invention is to provide an optical pickup capable of reproducing a recorded signal with a good S/N ratio.

Structure of the Invention The present invention provides an optical pickup in which an objective lens drive device including an objective lens and an optical block are substantially separable, in which at least one surface of the surfaces where the objective lens drive device and the optical block are in contact with each other is provided. , a spherical surface having a center on the optical axis of the objective lens and near the center of the objective lens is formed, and the optical axis of the objective lens is moved by sliding on both surfaces of the objective lens driving device and the optical block that are in contact with each other. By making the tilt adjustable,
Even if the objective lens is tilted, the inclination of the optical axis of the objective lens can be adjusted while keeping the position of the light spot and the distance between the disk and the objective lens constant, eliminating the need for extra readjustment as in the conventional case. Since the optical axis of the objective lens can be adjusted quickly, the optical spot on the disk can be narrowed down, making it possible to reproduce signals recorded on the disk with a good S/N ratio.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. This figure 3 and 4
In the figure, the same numbers are attached to the same components as in FIGS. 1 and 2. FIG. 3 shows an optical pickup in one embodiment of the present invention.
In FIG. 3, 1 is an objective lens, 2 is an objective lens drive device, 10 is a convex spherical surface formed or fixed to the bottom of the base of the objective lens drive device, 3 is an optical block, and 11 is the top surface of the optical block. concave spherical surface formed or fixed to 4a, 4b, 12
a, 12b are coil springs, 5a, 5b, 5c, 5
d is a screw hole, and 6a, 6b, 6c, and 6d are screws. A convex spherical surface 10 is fitted into a concave spherical surface 11, and the objective lens driving device 2 is attached to the optical block 3 so as to be rotatable about the center of the spheres 10,11. The coil springs 12a and 12b are compressed by screws 6c and 6d screwed into the screw holes 5c and 5d, and the objective lens driving device 2 is compressed with a constant force.
is pulled toward the optical block 3 side. The coil springs 4a and 4b are applied to the objective lens drive device 2 at a constant pressure.
is pushed up to prevent the spherical surfaces 10 and 11 from being gouged. The screws 6a and 6b are screws for adjusting the tilt of the objective lens, and by turning these two screws, the tilt of the objective lens 1 integrated with the objective lens driving device 2 is adjusted. As shown in FIG. 4, the spherical surfaces 10 and 11 have their centers at the center 7 of the objective lens 1, so even if the objective lens is tilted in any direction, the position of the light spot 9 does not change, as in the conventional example. Because the distance between the objective lens and the disk does not change or the position of the light spot shifts,
No need for extra readjustment. Therefore, the inclination of the objective lens can be adjusted to zero quickly, so that the assembly and adjustment time is significantly reduced compared to the conventional method. Furthermore, the adjustment is very simple as it only requires turning the two screws 6a and 6b in sequence. Further, since the convex spherical surface 10 is received by the concave spherical surface 11, the position and height of the objective lens driving device 2 are determined, and no jig for determining the position and height is required during assembly. In actual implementation, it is only necessary to change the shapes of the bottom of the base of the objective lens driving device 2 and the top of the optical block 3, and since the spherical surface can be formed at the same time during molding, the cost does not increase.

In this embodiment, spherical sliding is used, but a cylindrical convexity may be formed at the bottom of the objective lens driving device 2, or a circular hole may be formed at the top of the optical block 3. That is, the spherical surface may be located either at the bottom of the objective lens drive device or at the top of the optical block.

Furthermore, since the same effect can be obtained no matter how small the area of the spherical surface is, one spherical surface may be composed of three or more points.

Although this embodiment has a spherical surface between the objective lens driving device and the optical block, a mechanism for adjusting the inclination of the entire optical pickup by providing a spherical surface between the optical pickup and the block to which the optical pickup is attached is also available. Needless to say, it can also be applied to

Effects of the Invention In the optical pickup of the present invention, a spherical surface having a center on the optical axis of the objective lens and near the center of the objective lens is formed on at least one of the surfaces where the objective lens driving device and the optical block are in contact with each other. By making it possible to adjust the inclination of the optical axis of the objective lens by sliding the objective lens drive device and the optical block on both surfaces that contact each other, the position of the light spot and the distance between the disk and the objective lens can be adjusted even if the objective lens is tilted. The tilt of the optical axis of the objective lens can be adjusted while keeping it constant, eliminating the need for extra readjustment to compensate for changes in the light spot and changes in the distance between the disk and the objective lens. Adjustments can be made easily and quickly.

In addition, since the optical axis of the objective lens can be adjusted so that the optical axis of the objective lens and the disk surface are perpendicular, coma aberration caused by the tilt of the optical axes of the disk and objective lens can be suppressed, and the light spot on the disk can be narrowed down to a small size. As a result, the effect of improving the S/N of reproduction of signals recorded on the disk can be obtained. Furthermore, since the concave spherical surface receives other components, the height and position of the objective lens drive device are determined.
It has the advantage of not requiring any installation jig. As a result, the workability of adjusting the inclination of the objective lens is greatly improved, the number of assembly and adjustment steps can be significantly reduced, and production costs can be reduced.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view of a conventional optical pickup.
FIG. 2 is a schematic sectional view showing the drawbacks of a conventional optical pickup, FIG. 3 is an exploded perspective view showing an embodiment of the present invention, and FIG. 4 is a schematic sectional view showing the effects of the present invention. be. DESCRIPTION OF SYMBOLS 1... Objective lens, 2... Objective lens drive device, 3... Optical block, 4... Coil spring, 5
... screw hole, 6 ... screw, 7 ... center of objective lens, 8 ... optical axis, 9 ... light spot, 10 ... convex spherical surface, 12 ... coil spring.

Claims (1)

[Claims] 1. In an optical pickup in which an objective lens drive device including an objective lens and an optical block are substantially separable, at least one surface of the surfaces where the objective lens drive device and the optical block are in contact with each other is provided with the light of the objective lens. A spherical surface is formed on the axis and centered near the center of the objective lens, and the inclination of the optical axis of the objective lens can be adjusted by sliding on both surfaces of the objective lens driving device and the optical block that are in contact with each other. A light pick-up characterized by: