JPS60242525A - Driving device for objective lens - Google Patents

Abstract

PURPOSE:To perform accurate follow-up control over the objective lens by pressing, inserting and molding, or inserting and adhering a metallic tube in a resin- molded holding member for the objective lens. CONSTITUTION:Both-side terminals of a focus coil 7 and a tracking coil 8 are connected electrically to a substrate 5 through four supporting materials 3a-3d. Those four supporting materials 3a-3d form parallel springs, so the objective lens 1 is supported movably in two dimensions, i.e. vertically and perpendicularly to the supporting materials. Magnets 9a and 9b and a magnetic material yoke 10 form two magnetic gaps, into which the tracking coil 8 and focus coil 7 are inserted partially; and electricity is supplied to the coils to move the objective lens 1 and holding member 2 vertically and horizontally. Further, metallic tubes 11a and 11b pressed and adhered in the holding member 2 are tubular, so the rigidity of te holding member 2 is increased without any increase in the weight of a movable part including the holding member 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an objective lens driving device in a reproducing apparatus that optically reads information by sporadic projection of light onto a disk.

Conventional Structure and Problems The conventional objective lens driving device will be described below. FIG. 1 is an exploded perspective view of a conventional objective lens driving device.

1 is an objective lens, 2 is a resin-molded holding member for holding the objective lens, and 3 is a supporting member for movably supporting the holding member 2, which is made by inserting a metal wire into a rubber tube. 4 is a holder for holding the support material 3, 6 is a substrate for soldering the metal wire of the support material 3, 7 is a focus coil, 8 is a tracking coil, 9 is a magnet%, 10 is a magnetic material yoke%, 6 is a Holder 4 and board 5
This is a screw for fixing the magnetic material yoke 10 to the magnetic material yoke 10.

The operation of the conventional objective lens drive device configured as described above will be described below.

Both ends of the focus coil end and tracking coil 8 are
It is electrically connected to the substrate 6 by four supporting members 3. Furthermore, since the four supporting members 3 are all formed with parallel springs, they support the objective lens 1 so as to be movable vertically and two-dimensionally in a direction perpendicular to the supporting members. Two magnetic gaps are formed by the magnet 9 and the magnetic material yoke 1o. A tracking coil 8 and 11 parts of a focus coil 7 are inserted into this magnetic gap, and by passing current through these coils, the objective lens 1 and the holding member 2 can be moved upwardly and downwardly.
Move to the left and right in the vertical direction with the support.

By the way, in order to accurately control the objective lens to follow the information track on the disk, the objective lens driving device, especially the objective lens holding member, must be free from unnecessary resonance, or the frequency of the resonance must be reduced as much as possible. It is necessary to push it to the high range. In this conventional objective lens drive device,
As shown by the solid lines in FIGS. 2 and 3, there are resonance peaks of 10 klk in the tracking direction (horizontal direction) and 16 kHz in the focus direction (vertical direction), respectively. If such a peak exists, the gain of the tracking control and focus system cannot be set high, so the tracking control is likely to be lost due to abnormal grip or eccentricity of the disc, or due to external vibration. The objective lens cannot stably follow the information track on the disk. Figure 4 shows
FIG. 7 is a diagram showing the holding member of the objective lens viewed from above, and showing the deformation of the holding member when driven in the tracking direction. When a person is not resonating, B is in a resonant state.

At B, a single driving force is applied to the tracking coil, and the holding member is deflected due to the force mα due to the inertial mass m of the objective lens, and resonates at a frequency determined by the mass m of the objective lens and the rigidity of the holding member in the tracking direction. Also,
FIG. 5 is a side view of the objective lens holding member, showing the deformation of the holding member when driven in the focus direction.

Similarly to FIG. 3, B indicates a resonant state, which resonates at a frequency determined by the rigidity of the holding member in the focusing direction and the mass m of the objective lens.

Purpose of the Invention The present invention solves the above-mentioned conventional problems.By press-fitting, insert-molding, or inserting and gluing a non-magnetic metal tube into a resin-molded holding member, the resonance frequency of the holding member is increased and tracking is achieved. It is an object of the present invention to provide an objective lens drive device that can obtain a high control gain and stably reproduce information on a disk.

Structure of the Invention The present invention includes a holding member made of resin molding and movably arranged opposite to an information track on a disk.

This objective lens driving device includes an objective lens attached to the holding member and a non-magnetic metal tube, and by press-fitting, insert molding, or inserting and gluing the metal tube into the holding member, the holding member is Increasing the rigidity and raising the resonant frequency allows for a higher gain for follow-up control.

It is capable of reproducing information on a disc in a stable manner.

DESCRIPTION OF EMBODIMENTS FIG. 6 shows an exploded perspective view of an objective lens driving device in an embodiment of the present invention. In FIG. 6, reference numeral 1 denotes an objective lens, 24 a resin-molded holding member for holding the objective lens 1, and 3 a supporting member for movably supporting the holding member 2, in which a metal wire is inserted into a rubber tube. 4 is a holder for holding the support material 3, 6 is a substrate for soldering the metal wire of the support material 3, 7 is a focus coil, 8 is a tracking coil, 9 is a magnet, 10 (d magnetic material yoke, 6 are screws 11 (d thickness 0) for fixing the holder 4 and the substrate 5 to the magnetic material yoke 10;
．． It is a 6 mm extruded aluminum metal tube, and is press-fitted into the square hole of the holding member 2.

The operation of the objective lens driving device of this embodiment configured as described above will be described below. Both ends of the focus coil 7 and the tracking coil 8 are electrically connected to the substrate 6 by four supporting members 3. Also 4
Since each support member 3 forms a parallel spring, it supports the objective lens 1 so as to be movable vertically and two-dimensionally in a direction perpendicular to the support member. Two magnetic gaps are formed by the magnet 9 and the magnetic material yoke 1o. Parts of the tracking coil 8 and focus coil 7 are inserted into this magnetic gap, and by passing a current through these coils, the objective lens 1 and the holding member 2 are moved up and down and left and right in a direction perpendicular to the support member. .

In addition, since the metal tube 11 press-fitted and bonded to the holding member 2 is in the form of a tube, the rigidity of the holding member 2 is greatly increased without increasing the weight of movable objects including the holding member.
As shown by the broken lines in FIGS. 2 and 3, the total high-frequency resonance frequency is set to 1.6 times or more. Further, since the metal tube is made of extruded aluminum, eddy currents are generated in the aluminum by cutting the magnetic field of the magnetic gap, thereby dampening the vibrations of the movable object including the holding member.

As described above, according to this embodiment, by press-fitting and bonding the metal tube to the holding member, the rigidity of this holding member is greatly increased, preventing the holding member from deflecting during driving in the focus and tracking directions, and causing resonance. frequency 1.5
Since it is more than doubled to reach the tracking resonance peak f515 and the focus resonance peak Q20,
The objective lens can be stably tracked with respect to the information trunk on the disk. Also, since the metal tube is extruded aluminum, it can be manufactured at low cost.

In addition, since the holding member is tubular, the weight of the holding member increases little even though the holding member has high rigidity, and the loss of driving force can be minimized. Furthermore, the resonance peaks are 15i or more for both tracking and focusing.

Since the frequency is 20 kHz or more, which is near the limit of the audible range, it is difficult to hear unpleasant resonance sounds, and the quality of the playback device equipped with this objective lens drive device is not degraded.

In addition, the vibrations of movable objects including the holding member are damped by the eddy currents generated in the aluminum, and the information tracks on the disk are reduced in size.

In tri-rough plays such as 1o track jump and forced feed using all external power of the objective lens drive device, more stable operation can be achieved due to vibration damping.

In this example, an extruded aluminum material is used for the metal tube, but a molded material may also be used.

Other non-magnetic metals may also be used.

Effects of the Invention The present invention significantly increases the resonant frequency of the holding member by press-fitting, insert-molding, or inserting and gluing a metal tube into the resin-molded holding member of the objective lens.
Tracking control of objective lens to information track on disk 1
1i0 stably and accurately, and furthermore, since the resonant frequency is greatly increased, harsh sounds become less audible and the quality of the disc playback device can be improved. Also, due to the damping effect caused by eddy currents, the vibration level is better and more stable. Furthermore, by making the metal tube from an extruded aluminum material, it is possible to realize an excellent objective lens driving device that is inexpensive and does not require high costs.

[Brief explanation of drawings]

Figure 1 is an exploded perspective view of a conventional objective lens drive device;
3 and 3 are tracking transfer characteristic and focus transfer characteristic diagrams, respectively. FIGS. 4 and 5 are diagrams showing the deformation of the holding member at the time of trackinder resonance and focus resonance of a conventional objective lens drive device, respectively. The figure is an exploded perspective view of an objective lens driving device in one embodiment of the present invention. 1... Objective lens, 2... Holding member,
3...Support material, 4...Holder, 6.
...and... board, 6... screws. A... Focus coil, 8... Tracking coil% 9... Magnet, 10.
...Magnetic material yoke, 11...Metal tube. Name of agent: Patent attorney Toshio Nakao (1st person)
Fig. 1 Fig. 2/Fig. Shoulder narrow A - Fig. 3 Suzu I Wave diaphragm (Hz) Fig. 4 Fig. 5 A B Fig. 6

Claims (2)

[Claims] (1) A holding member made of resin molding and movably arranged opposite to the information track on the disk, an objective lens attached to this holding member, and a non-magnetic metal tube, An objective lens driving device characterized by having a metal tube press-fitted, insert-molded, or inserted and bonded. (2) The objective lens driving device according to claim 1, wherein the metal tube is an aluminum molded material.