JP2685840B2 - Objective lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention controls a track shift and a focus shift of a light spot focused on an information recording surface of an objective lens driving device, particularly an optical disc. The present invention relates to an objective lens driving device of a reproducing device or a recording device.

[Prior Art] FIGS. 7 and 8 are views showing a conventional objective lens driving device, FIG. 7 is a plan view, and FIG. 8 is a sectional view taken along line V1-V1 in FIG.

In FIG. 7 and FIG. 8, 1 is a fixed base, and a spindle 2 is erected on the fixed base 1 and a light window 3 is provided. Laser light is transmitted through the light window 3. It is supposed to pass. Reference numeral 4 denotes a lens holder which has a movable bearing 5 fitted to the support shaft 2 and is rotatably provided on the support shaft 2 and is movable in the longitudinal direction of the support shaft 2. An objective lens 6 having an optical axis parallel to the support shaft 2 is attached to a portion corresponding to the optical window 3 of the fixed base 1, and a counterweight 7 is attached to the opposite side via a movable bearing 5. There is. Reference numeral 8 denotes a supporting rubber that elastically holds the lens holder 4 and supports the objective lens 6 at a neutral position. The supporting rubbers 8 are opposed to each other via the lens holder 4 and extend in parallel to the horizontal direction for supporting. The portions 8a and 8b functioning as a frame and the portions 8c and 8b facing each other through the lens holder 4 and having both ends given a predetermined flexure attached to the support frame and functioning as elastic members are integrally formed. ing. The portions 8a and 8b functioning as the support frame have
Fixing pieces 9a, 9b, 9 provided on the upper end side of a holding body which is erected on the fixing base 1 so as to face each other via the lens holder 4.
The first mounting holes 10a, 10b, 10c, 10d into which c, 9d are fitted are formed, and the portions 8c, 8d functioning as the elastic material are
Second mounting holes 11a, 11b into which the inserters 4a, 4b provided so as to extend in the horizontal direction are inserted are formed on the lens holder 4 side.

On the other hand, 12 is a focus control permanent magnet provided on the fixed base 1 side, 13a and 13b are also track control permanent magnets, 14 is a yoke that also serves as a holder for the spindle 2 and the focus control permanent magnet 12, Denoted at 15a and 15b are yokes which also function as holding bodies for the supporting rubber 8 and the track control permanent magnets 13a and 13b.
Fixing pieces 9a to 9d fitted in the first mounting holes 10a to 10d of the support rubber 8 are provided on the upper ends of the 5a and 15b. Further, 16 is a focus control coil provided on the lens holder 4 side corresponding to the focus control permanent magnet 12, and 17a and 17b are also track control provided corresponding to the track control permanent magnets 13a and 13b. A coil, and the permanent magnet, the yoke, and the coil constitute a drive mechanism that drives the lens holder 4.

In the objective lens driving device configured as described above, since the cylindrical movable bearing 5 is fitted to the support shaft 2, the lens holder 4 is moved in the longitudinal direction of the support shaft 2, that is, the arrow A in FIG.
Is movably supported in the direction shown by arrow B in FIG.
It is held rotatably about the support shaft 2 in the direction.

Here, by passing a desired current through the focus control coil 16, the objective lens 6 fixed to the lens holder 4 can be moved in the direction of arrow A to perform focus control.
Further, since the objective lens 6 is fixed to the lens holder 4 at a position apart from the support shaft 2 by a predetermined distance, the objective lens 6 is moved in the direction of arrow B by applying a desired current to the track control coils 17a and 17b. Track control can be performed by rotating the track. Further, since the support rubber 8 has a function of holding the neutral position in the direction of the arrow B, the track control coil 17
The objective lens 6 is returned to the neutral position when the energization of a and 17b is released.

[Problems to be Solved by the Invention] The conventional objective lens driving device is configured as described above, and the first mounting holes 10a to 10d of the support rubber 8 are fixed pieces 9a to 9d provided on the fixed base 1 side. Is attached to the second mounting hole 11a, 11b of the support rubber 8 and the inserter 4 of the lens holder 4
a and 4b are installed. At this time, it is desirable that the objective lens 6 is supported with the center of the collimated light 18 as a neutral point as shown in FIG. 9, but the support rubber 8 is made of a material having high elasticity such as silicon rubber. Therefore, it is difficult to control the dimensional accuracy and the mounting accuracy, and the objective lens 6 may be supported as a neutral point at a position deviated from the center of the collimated light 18, as shown in FIG. Thus, when the objective lens 6 is supported with the position deviated from the center of the collimated light 18 as the neutral point, the effective diameter of the objective lens 6 protrudes from the collimated light 18, which deteriorates the light collecting performance.
There is a problem that the amplitude of the recording / reproducing signal is lowered, or the jitter when the objective lens 6 follows the rotation direction, the sensitivity of the focus control sensor, and the sensitivity of the track control sensor are asymmetrical with respect to the neutral point. It was

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an objective lens driving device that can correctly set the neutral position of the objective lens.

[Means for Solving the Problem] The objective lens driving device according to the present invention is provided with support frames 8a and 8b.
Alternatively, the first and second mounting holes 10a to 10d provided in the elastic members 8c and 8d,
At least one of 11a and 11b is formed from a plurality of holes arranged along the rotation direction of the movable holder 4.

[Operation] In the present invention, the first and second mounting holes 10a to 10d, 11a, 1
Select one hole from a plurality of holes formed in at least one of 1b, and attach the corresponding fixing piece 9a, 9b, 9c, 9d on the fixed base 1 side or the inserter 4a, 4b on the lens holder 4 side. Thereby, each movable holder 4 can be quantitatively displaced in the rotation direction, and the neutral position of the objective lens 6 can be accurately adjusted.

EXAMPLES Examples of the objective lens driving device according to the present invention will be described below with reference to FIGS. 1 and 2. 1 and 2 are exploded perspective views showing a first embodiment and a second embodiment, respectively, which are the same as or equivalent to those of the conventional example shown in FIGS. 7 and 8. The reference numerals are used and the description thereof is omitted.

FIG. 1 shows four first mounting holes 10a, 10b, 10 provided in portions 8a, 8b of the support rubber 8 which function as a support frame.
Of c and 10d, one 1st mounting hole 10c has 3 holes 101c and 102
This is an example formed from c and 103c, and the above three holes 101c to 103c.
Are arranged close to each other along the rotation direction of the lens holder 4, and one of these three holes 101c to 103c is selected and attached to the corresponding fixing piece 9c on the side of the fixing base 1 to obtain the objective lens. 6 is supported at a fixed position displaced in the direction of arrow B.

In this way, by selecting the first mounting hole for the fixing piece on the side of the fixing base 1 from the plurality of holes, the neutral position of the objective lens 6 is quantitatively set near the center of the collimated light emitted from the optical window 3. It becomes possible to adjust.

FIG. 2 shows that one of the two second mounting holes 11a and 11b provided in the portions 8c and 8d functioning as elastic members of the support rubber 8 has three second holes 111a and 112a. 113a
The three holes 111a to 113a are arranged close to each other along the rotation direction of the lens holder 4, and one of the three holes 111a to 113a is selected to make the lens holder 4 The objective lens 6 is supported at a fixed position displaced in the direction of arrow B by being attached to the corresponding inserter 4a on the side.

By selecting the second mounting hole for the insertion member on the lens holder 4 side from the plurality of holes in this way, the neutral position of the objective lens 6 can be adjusted by the collimated light emitted from the light window 3 as in the above embodiment. It becomes possible to adjust quantitatively near the center.

In addition, the number of the first mounting holes 10c shown in FIG.
The arrangement direction, or the number and pitch of the second mounting holes 11a shown in FIG. 2 are optimal from the required adjustment range required from the parts accuracy, assembly accuracy, etc. and the adjustment accuracy required from the specifications of the recording / playback signal. Is set to any value.

FIG. 3 shows a support rubber 8 similar to that described in FIG.
It is another embodiment in which the neutral position of the objective lens 6 is adjusted by displacing the first mounting hole. In FIG. 3, the first mounting hole 10
Three holes 101c, 102c, 103c forming c are arranged in a line. Further, as shown in the figure, by connecting the holes 101c to 103c with a thin groove, adjustment can be performed without removing the holes from the fixing piece 9c, and the workability is improved.

4 and 5 show another embodiment in which the neutral position of the objective lens 6 is adjusted by displacing the second mounting hole of the support rubber 8 similarly to that described with reference to FIG. FIG. 4 is a cross-sectional view of the inserter 4a provided on the lens holder 4 side on the plane P shown in FIG. 2, and FIG. 5 shows the shape of the second mounting hole 11a of the supporting rubber 8 corresponding thereto. As shown, three holes 111a, 112a, 113a having the same shape as the cross-sectional shape (diamond) of the inserter 4a are formed by being connected to each other. With this shape, the adjustment can be performed without removing the hole from the inserter 4a, and the workability is improved, as in the above-described embodiment.

FIG. 6 shows an example in which two second mounting holes 11a and 11b of the support rubber 8 are formed from three holes 111a to 113a and 111b to 113b, respectively. By selecting one hole,
The objective lens 6 is supported at a fixed position displaced in the direction of arrow B. As described above, it is obvious that the displacement may be generated in the plurality of mounting holes according to the required adjustment range and adjustment accuracy.

EFFECTS OF THE INVENTION As described above, according to the present invention, at least one of the first and second mounting holes is formed by a plurality of holes arranged along the rotation direction of the movable holder, so that the objective The neutral position of the lens can be adjusted so as to be located near the center of the collimated light, which has the effect of preventing various problems that occur when the lens is deviated from the center of the collimated light.

[Brief description of the drawings]

1 and 2 are exploded perspective views showing first and second embodiments of the present invention, FIG. 3 is an exploded perspective view showing a modified example of the above-mentioned FIG. 1, and FIGS. 4 and 5 are FIG. 6 is an exploded perspective view of an essential part showing another embodiment, and FIG. 7 and FIG. 8 are examples of conventional objective lens driving devices. And FIG. 9 and FIG. 10 are plan views for explaining the operating state of the conventional device. 1 is a fixed base, 2 is a support shaft, 4 is a lens holder (movable holder), 4a and 4b are inserters, 6 is an objective lens, 8 is support rubber, 8a and 8b are support frames, 8c and 8d are elastic materials, 9a to 9d are fixed pieces, 1
0a to 10d are first mounting holes, 101c to 103c are holes, and 11a and 11b are second.
Mounting holes, 111a to 113a, 111b to 113b are holes, 12 is a focus control permanent magnet, 13a and 13b are track control permanent magnets, 14 is a yoke, 15a and 15b are yokes (holding bodies), 16 is a focus control Coils, 17a and 17b are track control coils.

Claims (1)

(57) [Claims] 1. A movable holder, which is rotatably provided on a support shaft erected on a fixed base and is movable in the longitudinal direction of the support shaft, and which is attached to the movable holder and supports the support. An objective lens having an optical axis parallel to the axis, a fixing piece provided on the upper end side of a holding body which is erected on the fixing base so as to face each other through the movable holder, and extends in the horizontal direction,
A support frame having a first mounting hole into which the fixing piece fits, and a support frame facing each other through the movable holder, and both ends of the support frame mounted on the support frame and extending horizontally toward the movable holder. In an objective lens driving device provided with an elastic member having a second mounting hole into which the provided inserter is inserted, at least one of the first and second mounting holes is provided along the rotation direction of the movable holder. An objective lens driving device, characterized in that it is formed from a plurality of arranged holes.