JPH0480452B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an objective lens driving device for an optical disk player that projects a light spot onto a disk-shaped recording medium to optically read information.

Conventional configurations and their problems In general, in order to accurately read information in this type of optical disc player, focus control is required to control the distance between the objective lens and the information track position to prevent warping and wobbling of the disc. It is necessary to perform tracking control to control the objective lens to follow the eccentricity of the information track, and for this purpose, an objective lens drive device in the focus direction and the tracking direction is required.

In addition, the objective lens is usually held by a spring, but in the past it was held horizontally without any load being applied, so during actual use, the objective lens and its holder were used in a downward position due to their own weight. Ru. Therefore, there is a drawback that torsional resonance is likely to occur. Another method has been considered in which a predetermined bias current is passed through the drive coil in advance and the objective lens is lifted by the action of the bias current, but this method consumes excess power and tends to generate heat. It was hot.

OBJECTS OF THE INVENTION The present invention solves these conventional problems and aims to provide an objective lens driving device for an optical disc player that is less likely to cause torsional resonance and consumes less power and generates less heat.

Structure of the Invention The present invention includes an objective lens, a holder for holding the objective lens, a tracking direction drive coil and a focus direction drive coil fixed to the holder, a base, and a drive coil fixed to the base. a magnet arranged to face each of the drive coils, and one end fixed to the holder;
A spring member whose other end is fixed to the base constitutes an objective lens drive device, and the center of each of the drive coils is positioned at the center of the magnet when no current is applied to each of the drive coils. The spring material is configured to apply a bias equal to its own weight.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 shows details of its driving section.

Objective lens 1 is glued to holder 2,
A focusing direction driving coil 3 is wound around the holder 2, and two pairs of tracking direction driving coils 4 are bonded to both sides of the holder 2.

One end of the four metal wires 6 covered by the rubber tube 5 is fitted into a hole in the holder 2 and soldered to a printed circuit board 7 affixed to the holder 2, and the other end is soldered to a printed circuit board 8. has been done. This printed circuit board 8 is fixed to a base 10 via screws 9. The base 10 is made of a magnetic material, and two magnets 11, 11 are bonded so as to face each drive coil 3, 4, forming a magnetic circuit.

Both ends of the drive coil 3 in the focus direction and both ends of the drive coil 4 in the tracking direction are soldered to the printed circuit board 7, and each of the drive coils 3 and 4 is connected to four metal wires via the copper foil of the printed circuit board 7. The wires 6 are electrically coupled to each other.

Lead wires 12 are soldered to the printed circuit board 8 and electrically connected to the four metal wires 6, respectively.

In the above configuration, when a current is supplied to the lead wire 12, the current flows through the metal wire 6 to the drive coil 3 in the focus direction or the drive coil 4 in the tracking direction, and the holder 2 is moved by the electromagnetic action between each current and the magnet 11. They move in the focusing direction and the tracking direction, respectively, and the objective lens 1 is driven in each direction.

FIG. 3 is an explanatory diagram of the state when the metal wire 6 is soldered.

If the holder 2 is soldered horizontally, the holder 2 will drop under its own weight as shown by the broken line in FIG. Therefore, in this embodiment, as shown in FIG. 3b, the objective lens 1 and the holder 2 are
The holder 2 is soldered with the holder 2 raised in advance by the amount that it will lower due to its own weight. In this way, each drive coil 3, 4 connects to the magnet 1.
1 and will not cause torsional resonance.

FIG. 4 is a diagram in which a current is applied to the drive coil 4 in the tracking direction and the movement of the objective lens 1 is measured, where a shows the conventional characteristic and b shows the characteristic of the embodiment of the present invention. As is clear from Figure 4a, in the conventional device, there is a peak in the gain characteristic due to torsional resonance.
A dip occurs and the phase is delayed. Therefore, when control is applied, the transient characteristics deteriorate at this frequency.
In contrast, according to an embodiment of the present invention, FIG.
As shown in Figure 2, there are almost no peaks or dips caused by torsional resonance.

In addition, although the metal wire 6 was used as the spring material in the above embodiment, it does not necessarily have to be a wire.
It may be in the form of a thin plate. Further, in the above embodiment, the current is passed through the spring material, but the present invention is also effective even if the spring material is used only for mechanical holding.

Effects of the Invention According to the present invention, the drive coil in the tracking direction and the magnet directly face each other without applying a bias current, so that torsional resonance can be prevented while saving power and generating less heat.

Therefore, it is possible to realize an objective lens driving device for an optical disk player that has excellent transient characteristics when the control is applied and is completely free from instability such as occurs when there is torsional resonance.

Moreover, since soldering is performed with the holder raised in advance by the amount that the objective lens and holder sag due to their own weight, there is no need to make any adjustments after assembling the objective lens drive device, resulting in a very simple objective lens drive device. can be provided.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an embodiment of the present invention, Fig. 2 is an exploded perspective view of its main parts, Fig. 3 is a side view for explaining the state when metal wire is soldered, and Fig. 4 is a conventional It is a figure which compares and shows the characteristic of the example and the Example of this invention. 1... Objective lens, 2... Holder, 3... Drive coil in focus direction, 4... Drive coil in tracking direction, 5... Rubber tube, 6...
Metal wire, 7... Printed circuit board, 8... Printed circuit board, 9... Screw, 10... Base, 11... Magnet, 12... Lead wire.

Claims (1)

[Claims] 1. An objective lens, a holder that holds the objective lens, a tracking direction drive coil and a focus direction drive coil fixed to this holder, a base, and each of the above drive coils fixed to this base. It is composed of a magnet arranged to face each other and a plurality of metal springs, one end of which is soldered to the holder and the other end to a printed circuit board fixed to the base. The driving coils and the printed circuit board are electrically connected to each other through the metallic spring material, and the holder is movably supported, and the objective lens and the holder are attached to each other so as to sag due to their own weight. Perform the above soldering with the holder raised in advance, and make sure that the center of each coil is located at the center of the magnet with no current flowing through each of the drive coils.
An objective lens driving device for an optical disk player, characterized in that the metallic spring member is horizontal.