JPH0417128A - Tilt adjusting mechanism for objective lens driving device - Google Patents

Abstract

PURPOSE:To facilitate pressing adjustment and to improve the workability by pressing an tilt supporting member supporting a movable part holding an objective lens and driving it into a prescribed direction onto a fixed supporting base and providing a pressing adjusting means adjusting the depression from a direction different from the optical axis of the objective lens. CONSTITUTION:The tilt supporting member 25 consists of fixed parts 25a, 25b fixing leaf springs 13, 13 and a supporting body 25c supported freely tiltedly onto a fixed supporting base 27. A supporting part 27a supporting a tilt supporting member 25 is erected at one side ridge of the fixed supporting base 27 and screw holes 27c, 27d for adjusting screws 29, 29 with an eccentric pin as the pressing adjusting means are provided on both side faces of the supporting part 27a. Since the adjusting screws 29, 29 with an eccentric pin are provided on both side faces of the supporting part 27a, the adjusting screws 29, 29 with an eccentric pin are easily adjusted without being hindered by the optical axis adjusting photometric system such as a microscopic objective lens or the like at the adjustment of the optical axis of the objective lens 5. Thus, the job performance is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an objective lens drive device used in an optical information recording/reproducing device such as a magneto-optical disk device. This invention relates to a tilt adjustment mechanism.

[Conventional technology]

Optical information recording and reproducing devices using magneto-optical recording media have been developed in recent years and are being considered for application in various fields. An optical information recording/reproducing device records, reproduces, and erases information by irradiating a recording medium with a laser beam.

A magneto-optical disk device will be described as an example of this type of optical information recording/reproducing device with reference to FIG.

The magneto-optical disk device is equipped with a laser light source 1. ] An objective lens 5 is provided which focuses the laser beam, which has been deflected by the deflection mirror 2, onto the recording layer 4a of the magneto-optical disc 4, which is rotationally driven by the motor 3. Objective lens 5
is driven by an objective lens driving device 6 so as to focus the laser beam onto a target track of the recording layer 4a. The objective lens 5 is moved by an objective lens drive device 6, a laser light source 1 provided in a housing 8, and a deflection mirror 2 by a feeding mechanism 7 equipped with a drive means such as a linear motor.
At the same time, it is provided so as to be movable in the radial direction of the magneto-optical disk 4, so that a target track on the magneto-optical disk 4 can be accessed at high speed.

Further, the magneto-optical disk device is equipped with an electromagnetic coil 9, and when this electromagnetic coil 9 applies a constant magnetic field to the magneto-optical disk 4, information can be recorded or erased.

In such a magneto-optical disk device, the objective lens 5
If the laser beam is mounted at an angle with respect to the optical axis of the laser beam, aberrations will occur in the laser beam focused on the magneto-optical disk 4 by the objective lens 5, so that information on adjacent tracks will be read and crosstalk will likely occur. Therefore, in order to solve the above-mentioned problems, the following configurations have been proposed in the past.

As shown in FIG. 5, in the objective lens driving device 6,
The movable part 10 including the objective lens 5 includes plate springs 11...
It is supported by fixing members 15, 15 erected on the base 14 via the intermediate support 12 and plate springs 13, 13. A magnetic circuit 16.1 that drives the objective lens 5
6 and 17 are fixed on the base 14.

On the other hand, the housing 8 is provided with a deflection mirror 2 inside to guide laser light from the outside to the objective lens 5. Further, a holding hole 8a is provided at a corner of the upper end surface of the housing 8, and a steel ball 18 serving as a support body is inserted and fixed into this holding hole 8a. The steel ball 18 is held within the holding hole 8a so that a portion thereof protrudes from the upper end surface of the housing 8.

Further, while the upper end of the steel ball 18 is in contact with the lower end surface of the base 14, the tip 19a of the press fitting 19 is in contact with a point on the upper end surface of the base 14 opposite to this contact point.

In the objective lens driving device 6, this press fitting 19 has a screw 20.
By being tightened and pressed downward, the base 14 can freely tilt around the point of contact with the steel ball 18 as a fulcrum.

Further, the movement of the base 14 is restricted by adjustment screws 21, 21 so that it can move only in the vertical direction, but a spring is installed between the housing 8 and the base 14 around the adjustment screws 21, 21. 22, 22 are provided, and a pressing force is applied upward to the base 14. When the adjusting screws 21, 21 are rotated by a predetermined amount in this state, the adjusting screws 21, 21 move up and down according to the amount of rotation, and the inclination of the base 14 is adjusted.

In this way, according to the above configuration, even after the objective lens 5 is attached to the magneto-optical disk device main body, the objective lens 5
The inclination of the objective lens driving device 6 can be adjusted.

[Problem to be solved by the invention]

Incidentally, the tilt adjustment is performed while observing the laser beam focused into a spot by the objective lens 5 using an observation optical system including a microscope objective lens arranged opposite to the objective lens 5.

However, the conventional configuration described above has the problem that the microscope objective lens of the observation optical system gets in the way, making it difficult to turn the adjustment screws 21 and 21, resulting in poor workability.

[Means to solve the problem]

In order to solve the above problems, the tilt adjustment mechanism of the objective lens driving device according to the present invention includes a movable part that holds the objective lens and is driven in a predetermined direction, a tilt support member that supports the movable part, and a tilt support member that supports the movable part. A biasing means for supporting the member on the fixed support base, and a pressure adjustment means for pressing the tilting support member onto the fixed support base and adjusting this pressure from a direction different from the optical axis of the objective lens. It is characterized by the presence of

[For production]

According to the above configuration, the inclination of the tilting support member with respect to the fixed support base is determined by the balance between the urging force and the pressing force, and the pressing force is adjusted by adjusting the pressing force from a direction different from the optical axis of the objective lens. Since the means is provided, when adjusting the inclination of the objective lens, even if an observation optical system consisting of a microscope objective lens or the like is placed opposite the objective lens, pressure adjustment can be easily performed.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 3. Incidentally, the same numbers are added to the members having the same functions as those of the conventional example shown in FIG. 5.

As shown in FIG. 1, in the objective lens driving device 6,
The movable part 10 that holds the objective lens 5 includes focus coils 23 that generate electromagnetic force to drive the movable part 10 in the focusing direction, and generate electromagnetic force to drive the movable part 10 in the tracking direction. Tracking coils 24 are attached.

” 2, the focus coils 23, 23 and 1-
Movable part 1 with racking coils 24 and 24 attached
0 is supported by an intermediate support 12 via plate springs 11, and is movable in the focus direction using a fixed end of the intermediate support 12 as a fulcrum. Intermediate support 1
2 is supported by a tilting support member 25 via leaf springs 13, 13, and is movable in the tracking direction using a fixed end of the tilting support member 25 as a fulcrum.

The tilt support member 25 includes fixing parts 25a and 25b that fix the leaf springs 13 and 13, and a support body 25c that is tiltably supported on a fixed support base 27. A plate member 26 made of iron or the like is fixed as a magnetic piece to the lower end surface of the bent part on the side of the fixed part 25a of the support body 25c.

On the other hand, a magnetic circuit 1 for driving the objective lens 5 in the focus direction is mounted on a fixed support base 27 provided in a fixed state.
6 and 16, and a magnetic circuit 17 for driving the objective lens 5 in the tracking direction are fixed. A deflection mirror 2 is provided between the magnetic circuits 16 on the fixed support base 27 to guide laser light emitted from a laser light source (not shown) to the objective lens 5.

A tilting support member 25 is attached to one side edge of the fixed support base 27.
A support portion 27a is provided upright to support the. Support part 27
A is provided with a holding hole 27b at a position facing the plate member 26 with the tilting support member 25 attached to the support portion 27a. An annular permanent magnet 2 is placed in the holding hole 27b.
8 is fitted and fixed, and furthermore, a steel ball 18 serving as a support is inserted and fixed inside the permanent magnet 28. A portion of the steel ball 18 is attached to the permanent magnet 28 in order to provide an appropriate distance between the plate member 26 and the permanent magnet 28.
It is made to stand out more.

Further, on both sides of the support portion 27a, there are screw holes 27 into which adjustment screws 29 with eccentric pins as pressure adjustment means are screwed.
c.27d is provided. Here, the adjustment screw 29 with an eccentric pin is a screw having a protrusion, that is, an eccentric pin 29a, attached to the tip end surface at a position eccentric from the center of the screw, as shown in the figure.

Further, springs 22 and 22 as biasing means are compressed and sandwiched between the tilting support member 25 and the support part 27a, respectively, and adjustment screws 29 and 29 with eccentric pins are screwed into the holes 27c and 27d. By doing so, the eccentric pin 2
9a moves up and down while rotating, thereby restricting the movement of the tilting support member 25 in the up and down direction, as shown in FIG. The upper part of the steel ball 18 is in contact with the slope of the recess 26a provided in the plate member 26, so that the tilting support member 25 is stably supported by the steel ball 18 at a certain position. ing.

In the above configuration, since the magnetic force of the permanent magnet 28 acts as an attractive force on the plate member 26, the plate member 26 receives a downward force and is pressed against the steel ball 18, thereby causing the tilting support member 25 to can be tilted using the recessed portion 26a as a fulcrum.

The tilting support member 25 is always urged upward by the springs 22, but the eccentric pin-equipped adjustment screw 2
9 and 29, the height at which the eccentric pin 29a holds the tilting support member 25 can be changed by tightening or loosening the eccentric pin adjustment screws 29 and 29 as needed. It will be done. by this,
The tilt support member 25 tilts about the recessed portion 26a of the plate member 26, and the objective lens 5 (FIG. 1) similarly tilts. At this time, the focus coils 23, 23 and tracking coils 24, 24 of the movable part 10 are connected to the magnetic circuit 1, respectively.
The movable part 10 moves within the magnetic gaps 6, 16, and 17, but since the amount of inclination of the movable part 10 is about ±2° with respect to the adjusted inclination, the inclination adjustment has little effect on focus control and tracking control. It is safe to assume that there is no such thing.

In addition, as the adjustment screw 29 with an eccentric pin, specifically, for example, an eccentric pin 29a of φ1 mm is set 0.5 m from the center of the screw.
A 42mm screw installed in position m is used. Therefore, in this case, the vertical movement range of the eccentric pin 29a is 1 mm.

To adjust the optical axis of the objective lens 5, an observation optical system consisting of a microscope objective lens 31 (FIG. 2) with an outer diameter of 20 mm with almost no aberrations corrected, a TV camera (not shown), a TV monitor, etc. is used. That is, the microscope objective lens 3
1 at a position opposite to the objective lens 5, and the objective lens 5
The laser beam focused into a spot is expanded with a TV camera, and its image is displayed on the TV monitor. While observing this, the objective lens is adjusted so that the laser spot image becomes almost a perfect circle. 5 is the adjustment screw with eccentric pin 2
Adjusted by 9/29.

In the present invention, as described above, the adjustment screw 29 with eccentric pin
29 are provided on both sides of the support portion 27a, when adjusting the optical axis of the objective lens 5, the adjustment screws 29 and 29 with eccentric pins can be adjusted without being disturbed by the observation optical system for adjusting the optical axis such as the microscope objective lens 31. can be adjusted. This greatly improves workability.

Moreover, as described above, the plate member 26 is connected to the tilting support member 2.
5, it does not occupy a dedicated space in the tilting support member 25. Moreover, since the permanent magnet 28 is fixed within the holding hole 27b, the area occupied by the support portion 27a of the fixed support base 27 is small.

Furthermore, in this embodiment, the plate member 26 and the permanent magnet 28
This allows the tilting support member 25 to be attached to the steel ball 18 in a small space.
can be pressed. In addition, in order to effectively utilize the space on the fixed support base 27, the magnetic circuit 16
Since the magnetic circuits 16, 17 are provided on the fixed support base 27, the magnetic circuits 16, 16, and
There is no need to provide the base 14 that supports the movable portion 17 and the movable portion 10, and the objective lens driving device 6 can be made thinner.

In the above embodiment, the adjustment screw 29 with an eccentric pin is used as the pressure adjustment means, but the invention is not limited thereto. Any device may be used as long as it can be adjusted from a direction different from the axis. For example, as shown in FIG. 3, an adjustment screw 30 with a tapered pin, the tip of which has a tapered bottle shape, may be used as the pressure adjustment means. May be used.

The tilting support member 25 is always urged upward by the spring 22, but is pressed downward by a portion of the taper of the adjustment screw 30 with a taper pin, so that the adjustment screw 30 with a taper pin is only pressed by the required amount. By tightening or loosening, the height at which the tapered portion holds the tilting support member 25 can be changed. Note that members having the same functions as those shown in the drawings described above will be designated by the same reference numerals, and their descriptions will be omitted.

By the way, in the case of the eccentric pin adjustment screw 29 (Fig. 2),
When force is applied to the eccentric pin 29a from the side, the eccentric pin 29a
Depending on the position of the screw, the screw may loosen, but the adjustment screw 30 with a taper pin is superior in that the screw does not easily loosen even if force is applied from the side to a portion of the taper.

In addition, as the adjustment screw 30 with a taper pin, specifically, for example, a screw having a diameter of 42 mm and whose tip has a taper angle of 30 degrees is used. Therefore, in this case, the vertical movement range of part of the taper is 1 mm.

In the above embodiment, the tilting support member 25 (FIGS. 2 and 3)
The upper end of the tilting support member 25 (see figure) is pressed downward by the eccentric pin adjustment screw 29 or the tapered pin adjustment screw 30. The objective lens driving device can be further made thinner by providing a portion of the lens and pressing this portion downward with the eccentric pin adjustment screw 29 or the tapered pin adjustment screw 30.

Further, although the steel ball 18 is used as the support, the support is not limited to this, and may be a shaft with a rounded tip or a needle-like support. Further, instead of the spring 22, an elastic body such as a wave washer may be used.

Furthermore, even if the arrangement of the plate member 26 and the permanent magnets 28 is reversed to that of the present embodiment, the tilting support member 25 can be supported by the steel balls 18 as in the present embodiment.

〔Effect of the invention〕

As described above, the tilt adjustment mechanism of the objective lens drive device according to the present invention is capable of adjusting the pressing force, although the tilt of the tilting support member with respect to the fixed support base is determined by the balance between the urging force and the pressing force. Since we have provided a pressure adjustment means that performs pressure adjustment from a direction different from the optical axis of the objective lens, when adjusting the tilt of the objective lens, even if an observation optical system consisting of a microscope objective lens is placed opposite the objective lens, the pressure adjustment can be easily performed. This has the effect of significantly improving the workability of adjusting the tilt of the objective lens.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention. FIG. 1 is an exploded perspective view showing the configuration of an objective lens driving device. FIG. 2 is a longitudinal sectional view of the objective lens driving device showing the support structure of the tilting support member. FIG. 3 shows a modification of FIG. 2, and is a longitudinal sectional view of the objective lens drive device showing the support structure of the tilting support member. FIG. 4 is a schematic explanatory diagram showing the configuration of a magneto-optical disk device equipped with an objective lens drive device. FIG. 5 is an exploded perspective view showing the configuration of a conventional objective lens driving device. 5 is an objective lens, 6 is an objective lens drive device, 10 is a movable part, 16 and 17 are magnetic circuits, 18 is a steel ball, 22 is a spring (biasing means), 25 is a tilting support member, 26 is a plate member, 27 28 is a fixed support base, 28 is a permanent magnet, 29 is an adjustment screw with an eccentric pin (pressure adjustment means), and 30 is an adjustment screw with a taper pin (pressure adjustment means).

Claims (1)

[Claims] 1. A movable part that holds an objective lens and is driven in a predetermined direction, a tilting support member that supports the movable part, an urging means that supports the tilting support member on a fixed support base, and a fixed support for the tilting support member. 1. A tilt adjustment mechanism for an objective lens drive device, characterized in that a pressure adjustment means is provided for pressing the table and adjusting the pressure from a direction different from the optical axis of the objective lens.