JPS60140546A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To stabilize an oscillation characteristic by constituting a lens driving plate positioning damper with a silicone and burying lead wires of a tracking coil and a focusing coil in this silicone. CONSTITUTION:A lead wire 81 is buried in a lens driving plate positioning damper 8 and has one end soldered to a solder connecting part 92 of a substrate 9 for terminal and has the other connected to a substrate for fixed wiring, and a coil current is supplied there. Since a deforming part of the lead wire 81 is buried completely in the damper in this manner, an individual difference of oscillation characteristics due to influences of the lead wire 81 is eliminated. Further, since the damper 8 consists of a silicone rubber, change and degradation of the rigidity of the rubber due to heating of the lead wire 81 are prevented.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to an objective lens driving device.

[Conventional technology and its problems]

Recently, in the field of audio equipment, a digital recording and reproducing system using PCM (Pulse Coat Modulation) technology has emerged and is becoming popular in order to achieve as high fidelity as possible. In other words, this is called digital audio, and the principle is to make the audio characteristics far superior to conventional analog systems without depending on the characteristics of the recording medium. This is because it has been established. In this case, a system that uses a disk as a recording medium is called a DAD system, and optical, electrostatic, and mechanical playback systems are known. Regardless of which of these playback methods is adopted, the playback device that embodies it must be capable of satisfying various advanced functions and performances not found in conventional playback methods. Ru.

For example, in an optical disc record playback device that uses the CD (compact disc) method among optical playback methods, digital (PCM) is used for transparent resin discs.
12cIn in diameter and 1 in thickness, coated with a metal thin film that forms pits (irregularities with different reflectances) corresponding to the conversion data.
．． A 2 μm optical disk is driven by a CLV (constant linear velocity) method at a variable rotational speed of about 200 to 500 rpm. In this case, this disc requires various advanced functions and performance because the track pitch is 1.6 μm and it stores a huge amount of information that can be played in stereo for about an hour on one side. It is easy to understand that.

The next requirement for the above-mentioned optical disc record playback device is that each mechanical part can operate reliably with an organic and simple configuration with no waste, and that it can also be miniaturized while reducing consumption. The aim is to further improve the system by taking power-saving measures to reduce power consumption.

By the way, one of the specific targets of such a request is an objective lens driving device. In an optical disc playback device, the objective lens (so that the group or pit where the signal is recorded is always in focus and the track does not deviate from the track where the signal is recorded) is used.
It is necessary to apply focusing and tracking servo to follow the movement. There is a shaft sliding type objective lens drive mechanism for this purpose. As shown in FIG. 1, the shaft-sliding type lens drive device has an objective lens 4 attached to a lens drive plate 3 having a bearing 2 that can freely rotate and slide around an axis 1. The lens drive plate 3 is the axis 1
The lens driving plate 3 moves in the tracking direction (arrow N in the figure) by rotating around the axis 1, and moves in the focusing direction (arrow B in the figure) by sliding the lens drive plate 3 with respect to the axis 1. The neutral position of the lens driving plate in the tracking direction is determined by a damper 5 joined to the lens driving plate, and a focusing coil 6 applies a force t- in the focusing direction.

A tracking coil 7 applies force in the tracking direction. The tracking coil and focusing coil were soldered to a terminal board provided on the lens drive plate, and then connected to the fixed wiring board using a lead wire made by twisting together several thin enameled wires. Even if a lead wire with as low bending rigidity as possible is used, the rigidity of the lead wire is so large that it cannot be ignored compared to the rigidity of the damper, so the vibration characteristics of the lens drive plate are greatly influenced by the lead wire. On the other hand, since it is difficult to control the shape of this lead wire, its rigidity varies depending on the lead wire. As a result, the vibration characteristics of the lens drive plate vary depending on the individual device, and may not be compatible with the electric circuit for applying the servo.

[Purpose of the invention]

This invention improves the drawbacks of the conventional device mentioned above.
It is an object of the present invention to provide an objective lens drive device with little individual difference in vibration characteristics.

[Summary of the invention]

At the center of the lens drive plate to which the lens is attached, there is a bearing that allows rotation around an axis perpendicular to the lens drive plate and sliding in the axial direction, and a coil bobbin is arranged concentrically with the bearing. . A focusing coil is wound around the bobbin, and a tracking coil is attached to the outside of the focusing coil. (The inside and outside of the focusing coil and tracking coil may be swapped.)
A lens drive plate neutral positioning damper is attached to the lens drive plate to determine the neutral position of the lens drive plate.

The evening damper is made of silicone rubber, and the lead wires of the tracking coil and focusing coil are embedded therein. The lead wire is a bundle of metal wires, and the surface of the metal wires is coated with grease.

〔Effect of the invention〕

Since the lead wire is embedded in the damper, the shape of the lead wire is constant9, and there are no individual differences in vibration characteristics due to variations in lead wire rigidity, and the vibration characteristics do not match the servo circuit.

By using multiple metal wires for the lead wires embedded in the damper, friction occurs between the metal wires and a damping effect can be created. Since the Q value of the resonance point becomes small, stable servo can be obtained.

By applying grease to the surface of the metal wire.

The difference between the static friction and dynamic friction of the wire is reduced, resulting in a stable friction force, resulting in more stable vibration characteristics and a stable system.

[Embodiments of the invention]

Figure 2 is a partially sectional perspective view showing one embodiment of the present invention;
Figure (a) is a perspective view of the lens drive plate positioning damper.
Figure (b) is a partially sectional perspective view thereof.

An objective lens 4 is attached to a lens driving plate 3 having a bearing 2 which can freely rotate around an axis 10 and can move freely.The objective lens 4 is tracked by rotating the lens driving plate 3 around the axis 1. The lens drive plate 3 slides in the focusing direction (arrow B in the figure) by sliding in the direction (arrow B in the figure). The neutral position of the lens drive plate is determined by the lens drive plate positioning damper 8. A focusing coil 6 that provides a driving force in the focusing direction and a tracking coil 7 that provides a driving force in the tracking direction are soldered to a solder connection portion 91 of a terminal board 9 provided on the lens driving plate 3. A lead wire 81 is embedded in the lens driving plate positioning damper 8, and one end of the lead wire 81 is soldered to the solder connection portion 92 of the terminal board 9.
The other end is connected to the fixed wiring board, and current is supplied to the coil. In this way, since the deformable portion of the lead wire is completely embedded in the damper, individual differences in vibration characteristics due to the influence of the lead wire are eliminated, and the vibration characteristics do not match the servo circuit.

Since the Kokote lens drive plate positioning damper is made of silicone rubber, the heat generated by the lead wire is generated. There is no need to worry about changes in rubber rigidity or deterioration.

[Other embodiments of the invention]

If a plurality of metal wires are used as the lead wires 81 in the above embodiment, friction will occur between the metal wires when the damper is deformed, and a damping effect can be provided. Since the Q value of the primary resonance point of the vibration system becomes small, stable servo can be obtained. Furthermore, by applying grease to the surfaces of the plurality of metal wires, the friction between the metal wires becomes stable and a more stable system can be obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a partial cross-sectional perspective view illustrating a conventional objective lens driving device, FIG. 2 is a partial cross-sectional perspective view showing an embodiment of the present invention, and FIG. 3 (a) is a lens A perspective view showing the drive plate positioning damper, FIG. 3(b) is a partially sectional perspective view thereof. 1... Axis. 2...Bearing, 3...Lens I 4...Lens, 5.8...Lens drive plate positioning damper, 6...Focusing coil, 7...Tracking coil. 9... Terminal board, 81... Lead wire. 91.92...Solder connection part.

Claims (3)

[Claims] (1) The lens is moved in the focus direction by a lens drive plate that has a slide bearing that allows sliding in one direction and rotational movement around the axis and restricts other degrees of freedom, and a coil bobbin that is arranged concentrically with the bearing. and a lens drive plate positioning damper, wherein the damper is made of silicone, and lead wires of a tracking coil and a focusing coil are embedded in the damper. Lens drive device. (2) The objective lens drive device according to claim 1, wherein a plurality of metal wires are used as lead wires embedded in the damper. (3) The objective lens drive device according to claim 2, wherein grease is attached to the surfaces of the plurality of metal wires.