JPH0439743B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an objective lens for reading information optically recorded on a recording medium, which drives the objective lens in the direction of the optical axis and in the direction perpendicular to the optical axis. The present invention relates to a lens driving device.

[Conventional technology]

In optical reproducing devices that use laser light, signals are detected by focusing the laser light onto a minute spot using a lens, but in order to detect signals correctly, it is necessary to Focusing control for focusing the light spot on the information recording carrier and tracking control for making the light spot always follow the correct signal track are required. In order to perform these controls, an error detection device that detects each error and an actuator that moves the optical system to cancel the errors are required.

Conventionally, for this purpose, a special method has been used in which an optical system using an objective lens with a narrow angle of view is supported by an elastic support member such as a leaf spring, and vibrated in the direction of the optical axis and in the direction perpendicular to the optical axis using a corresponding electric signal. 1977-
It has been proposed in No. 138903, etc. In such a device that drives the objective lens two-dimensionally, possible methods for driving the objective lens include a method using an electromagnet, a voice coil method, and a method using a piezoelectric element, but the response performance of focusing and tracking is In order to keep it in good condition, it needs to be small and lightweight.

[Problem that the invention seeks to solve]

By the way, when assembling the objective lens drive device, the optical axis of the objective lens provided on the driven object and the optical axis of the optical system (e.g., laser diode, collimator lens, etc.) provided below the objective lens drive device must be It is important to match the For example, when playing a digital audio disk, a tilt accuracy of ±0.1° is required with respect to the assembly reference plane of the driven object, including the objective lens. The accuracy must be kept within a few micrometers, and the disadvantage is that the parts become extremely expensive.

[Means for solving problems]

a first portion including a magnetic circuit member that generates a magnetic field; a driven body including an objective lens, a tracking coil, and a focusing coil; and a driven body and the objective lens movable in a focusing direction and a tracking direction. In the objective lens driving device, the second part includes an elastic support member that is elastically supported and a support frame provided at a fixed end of the elastic support member. The frame is fixed with one set screw whose tightening direction is perpendicular to the optical axis of the objective lens.

[Effect]

The second part is rotatable about the axis of a single set screw in contrast to the first part to which the optical system is attached to the lower side, and the optical axis of the objective lens provided on the driven body can be easily aligned. Ru. Furthermore, the first part and the second part can be easily repaired or replaced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, on the upper surface of a base 2 made of die-cast material with an opening 1 in the center, magnets 4a and 4b are arranged in the form of a rectangular parallelepiped and magnetized in the thickness direction.
Magnetic circuit members 17a and 17b consisting of yoke plates 3a and 3b are fixed by screws 5a and 5b, etc., with the same polarities facing each other, as shown in FIG. Magnetic circuit members 17a, 17b
The directions of the magnetic poles and lines of magnetic force are as shown in FIG. 3, and magnetic fluxes are generated in the directions of the arrows in the magnetic fields 6a and 6b, respectively. The above is the first part shown in FIG. 6b.

Further, as shown in FIG. 2, objective lenses 20a to
The lens barrel 10 containing the lens 20c is bonded and fixed to the lens frames 11a and 11b, which are fixed to each other with an adhesive. A square focusing coil 12 is fixed to the outer surface of the square lens frame 11b with adhesive. Tracking coils 13a to 13d are placed in the squares of this focusing coil 12.
is glued. And lens frames 11a, 11
Support holders 18a and 18b are fixed to b with the focusing coil 12 in between, and the free ends a to d of the vertical parts of the support springs 8a to 8d are adhered to the support holders 18a and 18b with adhesive. There is. As shown in FIG. 2, the support springs 8a to 8d are composed of a plate spring part that is flexible in the optical axis direction and a plate spring part that is flexible in the direction perpendicular to the optical axis.
Its both ends are fixed to the moving frame 9 and the support frame 7 as shown in FIG. A terminal plate 14 is provided on the side surface of the support frame 7 opposite to the direction in which the support springs extend. The above is the second part shown in FIG. 6a.

Here, the electrical connections will be described. The four tracking coils 13a to 13d are connected in series, and both ends of the tracking coils 13a to 13d are soldered to free ends a and b of each vertical portion of the support springs 8a and 8b. Also,
Both ends of the focusing coil 12 are connected to support springs 8.
The free ends c and d of the vertical portions c and 8d are soldered. One end of each support spring 8a, 8b, 8c, 8d on the support frame side is electrically connected to the terminal 14a, 14b, 14c, 14d via the copper foil surface of the terminal board 14, respectively.

The above-mentioned first part and second part are formed by crimping the support frame 7 and yoke plate 3a of each part with one set screw 19, and as shown in FIG. is the magnetic air of the magnetic circuit members 17a, 17b 6a, 6
It is assembled to be held within b. Here, the insertion hole for the single set screw 19 has a direction in which the single set screw 19 is tightened.
It is configured to be perpendicular to the optical axis of c.
With such a simple configuration, when aligning the optical axes of the optical system located below the base 2 and the objective lenses 20a to 20c, the second portion can be rotated around the axis of the single set screw 19. By doing so, the optical axes of the objective lenses 20a to 20c can be adjusted very easily. Furthermore, if either the first part or the second part is damaged, it can be easily repaired or replaced by removing one set screw 19. Further, the terminal plate is also fixed by one set screw 19 as shown in FIG. 1, and since the terminals 14a to 14b are gathered at one end, wiring is easy.

Next, a method of driving the objective lens driving device of the embodiment will be described. First, tracking and focusing drive currents are supplied to the terminals 14a, 14b and 14c, 14d, respectively, and the springs 8a,
Tracking coils 13a, 13d and focusing coil 12 are energized via 8b, 8c, and 8d. Each of the coils is connected to the magnetic air 6a of the magnetic circuit members 17a and 17b as described above.
6b, and the magnetic circuit members 17a,
Due to the electromagnetic action of the magnetic field generated by 17b and the current flowing through each of the coils,
A to 13d receive a driving force in a direction perpendicular to the optical axis, and the focusing coil 12 receives a driving force in the direction of the optical axis. Each of the coils is connected to a lens frame 11 that holds a lens barrel 10 that accommodates objective lenses 20a to 20c.
a, 11b, the objective lens 2
0a to 20c are also driven in the direction perpendicular to the optical axis and in the direction of the optical axis, and tracking control and focusing control are performed.

〔Effect of the invention〕

As described above, according to the present invention, the optical axis adjustment of the objective lens can be performed extremely easily with an inexpensive and simple configuration. Further, it is easy to connect the terminal board to the terminal.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a two-dimensional objective lens driving device according to an embodiment of the present invention, FIG. 2 is an exploded view thereof, and FIG.
The figure is a perspective view of the magnetic circuit member, FIG. 4 is a plan view of FIG. 1, FIG. 5 is a front view of FIG. 1, and FIG. 6 is a sectional view before assembly. 2... Base, 3a, 3b ...Yoke plate,
4a, 4b...Magnet, 5a, 5b...Screw, 7...Support frame, 8a-8d...Support spring, 9
...Moving frame, 10... Lens barrel housing the objective lens, 11a, 11b... Lens frame, 12... Focusing coil, 13a to 13d... Tracking coil, 14... Terminal board, 17a, 17b …
...Magnetic circuit member, 19...Single set screw, 20
a to 20c...objective lens.

Claims (1)

[Scope of Claims] 1. A first portion including a magnetic circuit member that generates a magnetic field, a driven body including an objective lens, a tracking coil, and a focusing single coil, and a driven body that is moved in the focusing direction of the objective lens. and a second portion including an elastic support member elastically supported to be movable in the tracking direction, and a support frame provided at a fixed end of the elastic support member, wherein the first portion includes: An objective lens driving device characterized in that the support frame of the second portion is fixed with a set screw whose tightening direction is perpendicular to the optical axis of the objective lens. 2. In the objective lens driving device according to claim 1, the first part is provided with a terminal plate for energizing the two coils together with the second part, by means of the one set screw. An objective lens driving device characterized by being fixed.