JPH08273179A - Actuator for optical pickup device - Google Patents

Abstract

PURPOSE: To provide an actuator for an optical pickup device capable of protect ing a coil and a magnetic circuit and further easily assembling a part to be driven. CONSTITUTION: This actuator is provided with an annular flange 9d provided successively to an objective lens 9a and to which a focus coil 9b and tracking coils are fixed, and the magnetic circuit consisting of a magnet 9g and a yoke 9h fixed onto a base and driving the focus coil and tracking coils. These flanges are arranged so as to surround the magnetic circuit.

Description

Detailed Description of the Invention

[0001]

[0001]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator of an optical pickup device used for a video disc player, a compact disc player and the like.

[0003]

[0002]

[0004]

2. Description of the Related Art An actuator of an optical pickup device moves a driven part having an objective lens, a focus coil and a tracking coil fixed thereto by a magnetic circuit fixed to a base of the actuator, while keeping the posture of the objective lens parallel. By doing so, focus control and tracking control are performed, but since the coil, which is the heart of information reading, and the magnetic circuit are exposed, there is a risk of accidental touching. At the time of assembling, the lens surface was sometimes touched by touching the objective lens.

[0005]

[0003]

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to remedy the drawbacks of the above-mentioned conventional device, to protect the coil and the magnetic circuit, and to assemble the driven part easily. The purpose is to provide an actuator for the device.

[0007]

[0004]

[0008]

In order to solve the above-mentioned problems, an actuator of an optical pickup device of the present invention comprises an annular flange connected to an objective lens and having a focus coil and a tracking coil fixed thereto, and the flange. A suspension spring that supports the actuator base so as to be swingable in the focus direction and the tracking direction, and a magnetic circuit that is fixed to the actuator base and that drives the focus coil and the tracking coil and that includes a yoke are provided. It is characterized in that it is arranged so as to surround the circuit.

[0009]

[0005]

[0010]

By doing so, the flange of the actuator surrounds and protects the focus coil, tracking coil, magnet and the like, and the flange portion can be gripped during assembly, so that the lens surface is easy to handle. The risk of soiling is reduced.

[0011]

[0006]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical pickup device incorporating an actuator incorporating an actuator according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view and a front view thereof, and FIG. 2 is a plan view (partially sectional view) showing a state where a base 10 in which an actuator 9 is integrally incorporated is removed.

The optical pickup device includes a laser diode 2, a grating 3, a plate prism 4, a collimator lens 5, a triangular prism 6, a multilens 7 and a photodetector 8 which are incorporated in a body 1, and an actuator 9 which is incorporated in a base 10. It is composed by.

[0015]

FIG. 3 is an explanatory view showing the optical path,
In order to display on the same plane, the triangular prism 6, the objective lens 9a and the disk D are shown in the same figure as being twisted by 90 ° about the optical axis in the left-right direction. The laser beam emitted from the laser diode 2 is reflected by the plate prism 4 and the triangular prism 6, is focused by the objective lens 9a, and is converged on the disc D signal recording surface located above the optical pickup device. The reflected light modulated by is reflected again by the triangular prism 6, passes through the plate prism 4 and the multi-lens 7, is given astigmatism, and is guided to the photodetector 8.

[0016]

The plate prism 4 is formed by forming a metal thin film half mirror 4a on one surface of a glass plate having parallel planes, and is arranged at an angle of about 45 ° with respect to the optical axis. The laser beam emitted from is reflected by the half mirror 4a toward the triangular prism 6,
On the contrary, the reflected light sent from the triangular prism 6 (modulated by the signal recording surface of the disk D) passes through the plate prism 4 and is sent to the multi-lens 7.

[0017]

The reflected light from the signal recording surface of the disk D is
Astigmatism is imparted when passing through the plate prism 4.

The multi-lens 7 is a combination of a concave lens and a cylinder lens, gives astigmatism (in a direction different from that of the plate prism 4) to transmitted light (moves its position in the optical axis direction). (By changing) the converging position of the transmitted light.

[0019]

The photodetector 8 is composed of a focus detector composed of four photodetecting elements divided by two orthogonal straight lines and a pair of tracking detectors arranged on both sides of the focus detector. Is input to the actuator 9 as a signal for controlling the drive of the objective lens 9a.

[0020]

The astigmatism generated by combining the astigmatisms given by the plate prism 4 and the multi-lens 7 is set so as to face the direction in which the sensitivity of the focus detector of the photodetector 8 is maximized, and Disk D
In order to eliminate the influence of the shadow of the recording track on the focus detection, the direction of the recording track is set to coincide with the direction of one of the dividing lines of the focus detector.

By adjusting the position of the multi-lens 7 in the optical axis direction and the position in the plane orthogonal to the optical axis so that the speed of light transmitted through the plate prism 4 is correctly incident on the photodetector 8 (the photodetector 8 remains fixed). so)
The optical axis is adjusted and the focus is adjusted.

[0022]

FIG. 4 shows a supporting mechanism for the multi-lens 7. The multi-lens 7 has a lens sleeve 7b having a groove 7a in the circumferential direction so that the lens sleeve 7b is slidable in the axial direction and does not rotate. Supported by.

As shown in FIG. 2, the lens base 7d has its pair of wings 7c sandwiched between the positioning portion 1a of the body 1 and the elastic base retainer 1b, thereby forming a plane orthogonal to the optical axis. It is movably supported within.

The wings 7c of the lens base 7d have their tips facing the windows 1c formed on both sides of the body 1, respectively.
When aligning the optical axis, use the 1c jig from this window to
The position is adjusted in a plane that is sandwiched by and is orthogonal to the optical axis.

[0025]

When adjusting the focus, an eccentric pin is inserted through a hole formed in the back surface of the body 1 and the lens base 7d, and the eccentric pin is engaged with the groove 7a of the lens sleeve 7b to rotate. By moving, the position of the lens sleeve 7b in the optical axis direction is changed and adjusted.

[0026]

The plate prism 4 has its surface on the side where the half mirror 4a is provided adhered and fixed to the positioning portion 1d of the body 1,
Further, projections 11a for preventing movement are arranged at minute intervals on both end sides of the plate prism 4 and on the surface opposite to the half mirror 4a.

As shown in FIG. 5, the four projections 11a are provided on the back cover 11 and are used for temporary positioning when the plate prism 4 is attached to the body 1.

[0028]

As shown in FIG. 2, a G holder 3a for supporting the grating 3 and a laser diode 2 are mounted in a mounting hole 1e formed in a protruding portion on the side surface of the body 1.

The G holder 3a is positioned by bringing its front surface into contact with the first step portion 1f in the mounting hole 1e,
It is pressed forward by a G spring 3b provided between the rear surface and the base of the laser diode 2 and is supported so as to be rotationally adjustable about the optical axis.

[0030]

The laser diode 2 is positioned by bringing its shoulder into contact with the second step 1g in the mounting hole 1e, and its rear surface is pressed and supported by the LD presser 12.

The LD presser 12 has an engaging claw 12a at the tip thereof.
And two engaging claws 12a are formed at corresponding positions on the outer periphery of the protruding portion of the body 1.
The individual engaging portions 1h are engaged with each other.

[0032]

When attaching the G holder 3a and the laser diode 2, the G holder 3a, the washer, and the G spring are attached.
3b and the laser diode 2 are inserted in this order into the mounting hole 1e, and the LD is pressed onto the rear surface of the base of the laser diode 2.
12 are brought into contact and pressed to engage the engaging claws 12a of the two elastic legs with the engaging portions 1h of the body 1 by the elasticity of the elastic legs.

The laser diode 2 is very vulnerable to static electricity and is easily damaged. If the laser diode 2 is damaged, the engaging claw 12a of the LD retainer 12 is removed from the engaging portion 1h of the body 1 and the LD retainer 12 is pressed.
The laser diode 2 can be easily replaced by removing it.

[0034]

The collimator lens 5 has two legs 5b on the back surface.
Is supported by a collimator holder 5a having
As shown in the drawing, the two legs 5b and 5c are fitted into the positioning circular holes 1i of the body 1, respectively.

The shape of the cross section orthogonal to the axes of the two legs 5b and 5c is such that one leg 5b is circular and the other leg 5c is an ellipse that is long in the optical axis direction and short in the direction orthogonal to the optical axis. Shaped or rhombus, the legs 5c can move a little in the round hole 1i in the direction orthogonal to the optical axis, which makes it possible to keep the positioning accuracy in the optical axis direction high and the direction orthogonal to the optical axis. It is designed to allow a certain degree of dimensional error (distance between the leg and the hole).

[0036]

FIG. 7 is an exploded perspective view of an actuator for swingably supporting the objective lens 9a and performing focus control and tracking control.

The actuator 9 is integrated into the base 10 so that the objective lens 9a is located above the triangular prism 6 when the base 10 is attached to the body 1.

..

The positioning of the base 10 with respect to the body 1 is carried out similarly to the positioning of the collimator holder 5a shown in FIG. 6, by fitting the round pins and diamond pins projecting from the base 10 into the round holes provided in the pickup body. It is done in a way that fits together.

The actuator 9 includes an annular flange 9d to which the objective lens 9a, the focus coil 9b and the two tracking coils 9c are fixed, and the flange 9d to the projection of the base 10.
The suspension springs 9e and 9f are two pairs of right and left suspensions which are swingably supported by 10a, and magnets 9g and yokes 9h fixed to the base 10.

The annular flange 9d includes a focus coil 9b,
The tracking coil 9c, the magnet 9g, and the yoke 9h are arranged so as to surround them and protect them, and the weight of that portion acts to bring the center of gravity of the entire driven portion closer to the portions of the coils 9b and 9c that are the drive center. ing. Further, a counterweight for adjusting the position of the center of gravity may be attached to the flange 9d.

[0041]

The magnet 9g has a trapezoidal shape in which the width on the side facing the coil is wider than the width on the opposite side. As a result, for the purpose of downsizing the CD player, as shown in FIG.
When the pickup P is arranged so as to move in the diagonal direction of the CD player, and when the corner of the pickup P on the outer peripheral side on the magnet side is cut obliquely (so as not to hit the wall of the CD player), a flange is formed. Even if 9d vibrates greatly to the left and right (because of tracking), both tracking coils 9c (inner vertical portion) will not come off from the surface of the magnet 9g.

[0042]

It is sufficient that at least the corners of the magnet 9g on the outer peripheral side are carved, so that the shape is not limited to the isosceles trapezoid, and the outer peripheral side is more inclined than the inner peripheral side. It goes without saying that a trapezoidal shape may be used.

[0043]

In order to keep the posture of the objective lens 9a parallel to the optical axis when the objective lens 9a is driven to perform focus control and tracking control, the flange 9d is arranged in parallel with left and right sides thereof vertically spaced apart. It is supported by two sets of suspension springs 9e and 9f, respectively.

[0044]

Left and right total 4 sets of suspension springs 9e
As shown in FIG. 9, and 9f have a shape in which mounting terminals 9j are provided on both sides of two elastic plate-like conductors 9i arranged in parallel, and a flange 9d It is also used as a lead wire that supports and sends a control signal to the focus coil 9b and the tracking coil 9c.

[0045]

Upper and lower suspension springs 9e on one side and
As shown in the figure, 9f is integrally manufactured into a shape in which the terminals 9j on both sides thereof are connected by two claw portions 9k via narrow connecting portions, respectively. After the adhesive is fixed to the protrusion 10a and the flange 9d of the base 10 respectively, the two claws 9k are broken off to electrically separate the upper and lower suspension springs 9e and 9f. And the upper and lower suspension springs 9e and 9f can be attached accurately in parallel.

[0046]

The two plate-shaped conductors 9i forming the suspension springs 9e and 9f have different widths (for example, 0.10 mm and 0.12 mm) and different resonance frequencies, so that the suspension springs 9e and 9f are specified. It is difficult to resonate at the frequency of, and thus unnecessary resonance is unlikely to occur.

At this time, the more remarkable effect is obtained by arranging the wider plate-shaped conductor 9i on the outer side (that is, on the upper side in 9e and on the lower side in 9f). There seems to be

[0048]

Further, between the two plate-shaped conductors 9i of the suspension springs 9e and 9f, a dump material 9m made of a viscoelastic material such as butyl rubber or silicon rubber is filled, and thereby the resonance generated in the plate-shaped conductor 9i. Is designed to be attenuated.

[0049]

The manufacturing process of the suspension spring will be described with reference to FIGS. 10 and 11.

A large number of suspension springs 9e and 9f are simultaneously formed on one sheet 13 by etching in a state where the suspension springs 9e and 9f are connected to each other at several places so that they can be easily separated.

[0051]

After the sheet 13 is thoroughly washed, a primer is applied, and as shown in FIG. 11, the silk screen printer 14 is used to apply the dump material 9m using a pattern in which only the dump material 9m is passed. Temperature of 200 ℃
Then, the dump material of 9 m is baked for 15 minutes.

The primer is applied as a pretreatment.
This is because the dump material 9m can be easily attached.

[0053]

When the dump material 9m is applied by the silk screen printing machine 14, the printing brush is moved in the longitudinal direction of the plate-shaped conductor 9i.

In addition, the dump material 9m contains several μm to several tens of μm.
m-sized flaky particles 9n (for example, flaky graphite,
If mica or the like is mixed in, the action as a so-called book damper for the two plate-shaped conductors 9i becomes strong, and the "shear braking" effect becomes large.

Furthermore, by adopting silk screen printing, as shown in FIG. 12, flaky particles are formed.
This further enhances the "shear braking" effect, since the 9n are aligned in the direction of movement of the printing brush (ie the longitudinal direction of the plate conductor 9i).

[0056]

In the above embodiment, the number of plate-shaped conductors 9i constituting each suspension spring 9e and 9f is two, but the number is not limited to this and may be three or more. Is.

[0057]

[0032]

[0058]

As described above, in the actuator of the optical pickup device of the present invention, since the annular flange is arranged so as to surround the focus coil, the tracking coil, the magnet, the yoke, etc., these should be protected. In addition, since the flange portion can be gripped when the driven portion is incorporated in the magnetic circuit, it is easy to handle, and there is little risk that the lens surface will be contaminated by touching the objective lens.

[Brief description of drawings]

FIG. 1 is a plan view and a front view of an optical pickup device incorporating an actuator according to an embodiment of the present invention.

FIG. 2 is a plan view with the cover removed.

FIG. 3 is an explanatory diagram showing the optical path.

FIG. 4 is a perspective view showing a supporting mechanism of the Matsuri lens.

FIG. 5 is a perspective view of the back cover.

FIG. 6 is an explanatory view showing the collimator lens positioning means.

FIG. 7 is an exploded perspective view of the actuator.

FIG. 8 is a plan view showing the arrangement of the CD player.

FIG. 9 is a plan view of a suspension spring.

FIG. 10 is a plan view of a manufacturing process of the suspension spring.

FIG. 11 is a side view showing the silk screen printing.

FIG. 12 is an explanatory diagram of a dumping agent for the suspension spring.

[Explanation of symbols]

 9 ... Actuator 9a ... Objective lens 9b ... Focus coil 9c ... Tracking coil 9d ... Flange 9g ... Magnet 9h ... Yoke

Claims (1)

[Claims] 1. An annular flange connected to an objective lens and having a focus coil and a tracking coil fixed thereto, a suspension spring for supporting the flange on an actuator base so as to be swingable in the focus direction and the tracking direction, and an actuator base. A magnetic circuit that is fixed to a magnet and that drives a focus coil and a tracking coil, and a yoke,
An actuator for an optical pickup device, wherein the flange is arranged so as to surround the magnetic circuit.