JPS6246442A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To drive directly an objective lens in three axial directions and to reduce the titled device in size, weight and price by supporting the objective lens with wire-like springs and spiral springs so as to move the lens in three axial directions and arranging three kinds of driving coils. CONSTITUTION:An objective lens holding member 16 is coupled with an intermediate holding member 28 through four wire-like springs 26a-26d and the intermediate member 28 is coupled with a base board 29 through two spiral plate springs 27a, 27b. Thereby, the objective lens 15 can be supported so as to be optionally moved in the three axial directions. Three kinds of coils consisting of a focus driving coil 21, tracking driving coils 22a, 22b and time base driving coils 23a, 23b are arranged. When a prescribed control current is made to flow into the driving coils under said constitution, the objective lens 15 is directly driven in the three axial directions. Thus, the optical system can be simplified and the titled device can be reduced in size, weight and price.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides an objective lens in a recording and reproducing apparatus that optically records and reads information by irradiating a light spot onto a disk-shaped recording medium in three orthogonal axes directions. The present invention relates to an objective lens and a driving device that are driven by the objective lens.

(Prior Art) FIG. 5 is an explanatory diagram showing an example of a conventional optical disc reproducing device. In the figure, a light beam emitted from a laser device 1 passes through a beam splitter 2, is polarized in the tangential direction and radial direction by a tangential mirror (time base mirror) 3 and a tracking mirror 4, and is polarized by an objective lens 5 into a disk 6. The signal is focused on the recording surface of n. disk 6
The reflected light beam modulated by 0 bit 7 and reflected by the reflective film follows the optical path in the opposite direction and is reflected by the beam splitter 2,
The input signal is converted into an electrical signal by an optical converter 8. In this signal reproduction, following the signal recorded bit 7 is carried out by a focusing unit 9 that focuses, a tracking mirror 4 that swings a light beam in a radial direction to track the track number,
This is performed by a tangential mirror (time pace mirror) 3 that swings the light beam in the tangential direction in order to remove time axis fluctuations of the reproduced signal.

FIG. 6 is a sectional view showing an example of the structure of the focusing unit 9 shown in FIG.

In the figure, a drive coil 1 provided on an objective lens 5
0 is placed in the magnetic gap of the magnetic path consisting of the permanent magnet 11 and the plates 12 and 13, and due to the interaction between the current sent to the drive coil 10 as a control signal and the gap magnetic flux,
The objective lens 5 is driven in two directions.

(Problems to be Solved by the Invention) In the conventional example, since the light flux is deflected by a mirror, the objective lens must have a wide viewing angle in order to always be able to receive and accept the deflected light flux. In addition to the high lens price, the use of mirrors made mounting, assembly, and adjustment complicated, and the equipment also had the disadvantage of increasing in size.

The purpose of the present invention is to eliminate the drawbacks of the conventional technology and to make it possible to directly drive the objective lens □ in three axial directions without the need for deflecting the light beam with a mirror, thereby reducing the size, weight, and cost of the device. The object of the present invention is to provide a principal-dimensional lens drive device that can realize the following.

(Means for solving the problem) The objective lens driving device of the present invention includes an objective lens,
1 objective lens holding member and one end of the objective lens holding member.
□Four wire-like springs, the other end of which is fixed to the intermediate holding member, support the objective lens movably in the tracking direction and the time base direction, which are substantially parallel to the disk surface; two upper and lower spiral-wound plate springs, the other end of which is fixed to the base of the objective lens driving device, on the holding member and support the objective lens in a movable state in a focusing direction substantially perpendicular to the disk surface; A focus drive coil wound around the objective lens holding member, a tracking drive coil consisting of four flat coils fixed to the objective lens holding member, and four flat coils also fixed to the objective lens holding member. The three types of drive coils are located in the gap between a time base drive coil consisting of a coil, and a magnetic circuit consisting of a U-shaped magnetic yoke and a permanent magnet fixed to the magnetic yoke. The structure is such that thrust is generated in the coil for use.

(Function) The present invention moves the objective lens in parallel in the tracking direction and the time pace direction by connecting and supporting the objective lens holding member with the intermediate holding member using four wire springs in a direction perpendicular to the disk surface. In addition, by arranging two upper and lower spiral-wound leaf springs parallel to each other horizontally with respect to the disk surface, and by connecting and supporting the intermediate holding member and the base, the objective lens can be moved in the focus direction. It is possible to move parallel to .

According to the present invention, the objective lens can be directly driven in three axial directions without the need to use a mirror to shake the light beam as in the past, and the apparatus can be made smaller and lighter.

Therefore, it can be used commonly for optical video discs and optical discs, and does not require the use of expensive wide-viewing-angle lenses or complicated optical axis adjustment.

(Example) An example of the present invention is based on FIGS. 1 to 4:
I will explain.

FIG. 1 is a schematic diagram showing the support system of the objective lens driving device of the present invention.

In the same figure, reference numeral 15 denotes an objective lens that focuses the radar light onto the disk, and an objective lens holding member 16 that holds the objective lens 15 is provided with an intermediate holding member 17 and a lens 4 that is provided with the same length in the direction perpendicular to the disk surface. Book wire spring 18
Between the intermediate holding member 17 and the base 19 of the objective lens driving device, two spiral leaf springs 20, upper and lower, are arranged parallel to each other in a direction horizontal to the disk surface and are connected and supported to each other. There is.

Therefore, the four wire springs 18 have weak spring force in the Can be translated in parallel (Y direction). - Since the crab spiral leaf springs 20 are arranged in parallel, the intermediate holding member 17 can be translated in parallel only in the focus direction (two directions).

FIG. 2(a) is a sectional view showing the drive system of the objective lens driving device of the present invention, and FIG. 2(b) is a plan view thereof.

In the figure, a focus drive coil 21 is wound around the outer periphery of the holding member 16, and tracking drive coils 22a and 22b, each consisting of a set of four flat coils, are fixed to the outer periphery. Further, time pace drive coils 23a and 23b, which are also made up of a set of four flat coils, are fixed to a surface perpendicular to that surface. The permanent magnet 24 is magnetized in the thickness direction, and has a U-shaped magnetic yoke 25.
The four wire springs 18 are attached to the objective lens holding member 16 and the intermediate holding member 17 so that the three types of driving coils are arranged in each of the four magnetic gaps. There is.

Now, when current is passed through the three types of drive coils, due to the interaction with the magnetic flux in the air gap, the focus drive coil 21 of the objective lens 15 moves in the Z direction, and the tracking drive coil 22 (22a, 22b) moves the time in the X direction. They are each driven in the Y direction by the pace drive coils 23 (23a, 23b).

FIG. 3 shows a cross-sectional view of the entire combination of the support system and drive system of the objective lens drive device of the present invention.

Here, the four wire springs 18 shown in FIG. 1 are specifically illustrated, and are designated as 26a and 26b, respectively. Moreover, the upper and lower two spirally wound leaf springs 20 are each 27a.
, 27b.

Further, the intermediate holding member 17 is also shown as 28, and the base 19 of the objective lens driving device is also shown as 29.

FIG. 4 is a perspective view showing the objective lens driving device of the present invention in an exploded manner for easy viewing. In the same figure, 30
is a connecting cylinder for connecting and fixing the inner circumferences of the two upper and lower spiral leaf springs 27a and 27b, into which the intermediate holding member 28 is inserted and fixed. A spacer cylinder 31 fixes the inner circumferences of the two upper and lower spiral leaf springs 27a and 27b to determine the position between the leaf springs. 32a.

32b is an outer circumference fixing ring for fixing the outer circumference of a general-purpose leaf spring, and 33 is an inner circumference fixing ring for fixing the inner circumference of the leaf spring.

Although not shown in the figure, there are four wire springs 26 (26a, 26b, 26c, 26d) and two spiral leaf springs 27 (27a).

27b) is laminated with a viscoelastic material 9 to optimize secondary resonance and damping characteristics.

(Effects of the Invention) According to the present invention, it becomes possible to directly drive the objective lens in three directions, and a function that combines the conventional focusing unit, tracking mirror, and tangential mirror into one is obtained. This eliminates the need for expensive objective lenses or complicated optical axis adjustment, reducing cost.

Furthermore, the small and lightweight structure allows the use of optical video discs and compact discs, which has a great practical effect.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing a support system of an objective lens drive device in an embodiment of the present invention, Fig. 2 (a) is a sectional view showing the drive system, and Fig. The figure is a cross-sectional view of the entire support system and drive system combined, FIG. 4 is an exploded perspective view of the objective lens drive device, FIG. 5 is a perspective view of essential parts of a conventional optical disc playback device, and FIG. 6 is the same sectional view. 1...Laser device, 2...Beam splitter, 3.
...Tangential mirror, 4...Tracking mirror, 5.15...Objective lens, 6...Disc, 7
Bit, 8 Optical converter, 9 Focusing unit, 10 Drive coil, 11 Permanent magnet, 12.13 Grate, 16 Objective holding member, 17.28...Intermediate holding member, 18.26a
, 26b, 26c. 26d... wire spring, 19.29... base, 2
0゜27a, 27b... spiral leaf spring, 21...
・Focus drive coil, 22m, 22b...Pack tracking drive coil, 23a * 23b...
Time base drive coil, 24...Permanent magnet, 25
...Magnetic material yoke, 30...Connection cylinder, 31...
Spacer cylinder, 32m, 32b... outer periphery fixing ring,
33... Inner circumference fixing ring. Figure 1 □゛・1′. Figure 2 (b)

Claims (1)

[Claims] an objective lens; an objective lens holding member; one end is fixed to the objective lens holding member and the other end is fixed to an intermediate holding member, and the objective lens is supported movably in a tracking direction substantially parallel to a disk surface and in a time base direction. four wire-shaped springs, one end of which is fixed to the intermediate holding member and the other end of which is fixed to the base of the objective lens driving device, and the objective lens can be moved in a focusing direction substantially perpendicular to the disk surface. two spiral leaf springs, upper and lower, that support the
A focus drive coil wound around the objective lens holding member, a tracking drive coil consisting of four flattened coils fixed to the objective lens holding member, and a tracking drive coil consisting of four flat coils also fixed to the objective lens holding member. The three types of drive coils are located in the gap between a time base drive coil consisting of three flat coils, a magnetic yoke with a U-shaped cross section, and a permanent magnet fixed to the magnetic yoke. A three-dimensional objective lens drive device, characterized in that it is configured such that each drive coil generates a thrust force.