JPH0470703B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a structure of a suspension spring that swingably supports an objective lens in an optical pickup device used for a video disc player, a compact disc player, etc. It is related to.

〓Summary of the Invention〓 In an optical pickup device, an objective lens is swingably supported by suspension springs in order to perform focus control and tracking control, and each suspension spring is connected to a plurality of parallelly arranged They each consist of a plate-shaped conductor and a damping material made of a viscoelastic material filled with scale-like particles that is filled between these plate-shaped conductors, and the suspension is achieved by damping the resonance of each plate-shaped conductor with the damping material. This is designed to suppress unnecessary resonance that occurs in the spring.

〓Conventional technology〓 Conventionally, in an optical pickup device, an objective lens is swingably supported by two sets of suspension springs on each side, and a focus coil and a tracking coil are fixed to the objective lens. It is known to drive the objective lens to move parallel to the optical axis to perform focus control and tracking control.

However, such a device has the disadvantage that all the suspension springs resonate at a specific frequency, which causes noise to be mixed into the reproduced signal.

〓Problems to be Solved by the Invention〓 The purpose of the present invention is to improve the above-mentioned drawbacks of the conventional device, and to provide an optical pickup that suppresses the resonance of the suspension spring and prevents an adverse effect on the reproduced signal. The purpose is to provide equipment.

〓Means for Solving the Problems〓 In order to achieve the above object, the optical pickup device of the present invention includes a plurality of plate-like conductors arranged in parallel and a scale-like conductor filled between these plate-like conductors. and a damping material made of a viscoelastic material mixed with particles, the suspension springs are arranged in parallel on both sides of the objective lens at vertical intervals, and the objective lens is oscillated by the suspension springs. I try to support it as much as possible.

〓Effect〓 By doing this, the damping material made of a viscoelastic material mixed with scale-like particles, which is filled between the plurality of plate-shaped conductors constituting each suspension spring, can Since the resonance is attenuated, unnecessary resonance is less likely to occur in the suspension spring, and an adverse effect on the reproduced signal can be prevented.

Embodiment An optical pickup device which is 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 the state where the base 10 in which the actuator 9 is integrated is removed.

The optical pick-up device includes a laser diode 2, a grating 3, a plate prism 4, a collimator lens 5, a triangular prism 6, a multi-lens 7, a photodetector 8, and an actuator 9 incorporated in a base 10. has been done.

FIG. 3 is an explanatory diagram showing the optical path. In order to display the optical path on the same plane, the triangular prism 6, objective lens 9a, and disk D are twisted 90 degrees around the optical axis in the left-right direction in the figure. Shown in ivy state.

The laser beam emitted from the laser diode 2 is reflected by the plate prism 4 and the triangular prism 6, focused by the objective lens 9a, and focused on the signal recording surface of the disk D located above the optical pickup device, where it is recorded. The reflected light modulated by the signal 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.

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

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

The multi-lens 7 is a combination of a concave lens and a cylinder lens, and provides astigmatism (in a direction different from that of the plate prism 4) to transmitted light, as well as (by moving its position in the optical axis direction). Change the convergence position of transmitted light.

The photodetector 8 is composed of a focus detector consisting of four photodetecting elements divided by two orthogonal straight lines, and a pair of tracking detectors placed on both sides of the focus detector, and the detection signals of these detectors are sent to the objective lens. The signal 9a is input to the actuator 9 as a drive control signal.

The direction in which astigmatism, which is the combination of the astigmatism given by the plate prism 4 and the multi-lens 7, is generated is set so that it faces the direction in which the sensitivity of the focus detector of the photodetector 8 is maximized. In order to eliminate the influence of the shadow of the recording track on focus detection, the direction of the recording track is set to match the direction of one dividing line of the focus detector.

By adjusting the position of the multi-lens 7 in the optical axis direction and the position in the plane perpendicular to the optical axis so that the light beam transmitted through the plate prism 4 enters the photodetector 8 correctly (while keeping the photodetector 8 fixed) It is designed for alignment and focus adjustment.

FIG. 4 shows the support mechanism of the multi-lens 7. The multi-lens 7 has grooves 7 in the circumferential direction.
This lens sleeve 7b is supported within a lens base 7d having a pair of wings 7c so as to be slidable in its axial direction but not rotated.

As shown in FIG. 2, the lens base 7d has its pair of wing parts 7c held between the positioning part 1a of the body 1 and the elastic base presser 1b, and is thereby moved in a plane perpendicular to the optical axis. Possibly supported.

The tips of the wing portions 7c of the lens base 7d face the windows 1c formed on both sides of the body 1, and when aligning the optical axis, the wing portions 7c are inserted through the windows 1c using a jig. Position adjustment is performed within a plane perpendicular to the clamping optical axis.

Further, when adjusting the focus, an eccentric pin is inserted through a hole formed on 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 and rotated. Adjustment is made by changing the position of the lens sleeve 7b in the optical axis direction.

The plate prism 4 is adhesively fixed to the positioning part 1d of the body 1 on the side on which the half mirror 4a is provided, and is also fixed at a small interval on both ends of the plate prism 4 and on the surface opposite to the half mirror 4a. Four protrusions 11a are arranged to prevent movement.

As shown in FIG. 5, these four protrusions 11a are provided to protrude from the back cover 11 and are used for temporary positioning when attaching the plate prism 4 to the body 1.

As shown in FIG. 2, a G holder 3a that supports the grating 3 and a laser diode 2 are installed in an attachment hole 1e formed in a protrusion 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 1f in the mounting hole 1e, and is pushed forward by the G spring 3b provided between its rear surface and the base of the laser diode 2. It is supported so that it can be rotated and adjusted around the optical axis.

The laser diode 2 is positioned by bringing the shoulder of its base 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 foot 12 has an engaging claw 12a at its tip.
The two engaging claws 12a are respectively engaged with two engaging parts 1h formed at corresponding positions on the outer periphery of the protruding part of the body 1. .

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

The laser diode 2 is very susceptible to static electricity and easily damaged, but if it is damaged, the laser diode 2 can be easily removed by removing the engaging claw 12a of the LD presser 12 from the engaging portion 1h of the body 1 and removing the LD presser 12. Diode 2 can be replaced individually.

The collimator lens 5 is supported by a collimator holder 5a having two legs 5b and 5c on the back surface, and as shown in FIG.
and 5c are fitted into positioning round holes 1i of the body 1, respectively.

The shape of the cross section perpendicular to the axis of the two legs 5b and 5c is such that one leg 5b has a circular shape, and the other leg 5c has an elliptical or diamond shape that is long in the optical axis direction and short in the direction perpendicular to the optical axis. The legs 5c can move slightly in the direction perpendicular to the optical axis within the round hole 1i, thereby maintaining high positioning accuracy in the optical axis direction. A certain degree of dimensional error (between the distance between the round holes and the distance between the round holes) is allowed.

FIG. 7 is an exploded perspective view of the actuator 9 that swingably supports the objective lens 9a and performs focus control and tracking control.

The actuator 9 is integrated into the base 10, and the objective lens 9a is positioned 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 performed by fitting the round pin and the diamond pin protruding from the base 10 into the round holes provided in the pick-up body, respectively, in the same manner as the positioning of the collimator holder 5a shown in FIG. It is carried out in

The actuator 9 includes a flange 9d to which an objective lens 9a, a focus coil 9b, and two tracking coils 9c are fixed, and two sets of suspension springs each on the left and right that swingably support the flange 9d on a protrusion 10a of a base 10. 9e and 9f and magnet 9g fixed to base 10
and a yoke 9h.

Magnet 9g has a trapezoidal shape, with the side facing the coil wider than the opposite side.
For the purpose of downsizing the CD player, as shown in FIG.
Even if the flange 9d vibrates from side to side (for tracking), both tracking coils 9c are (inner vertical part of) is magnet 9
It is designed so that it does not fall out of the g plane.

Note that it is sufficient that the magnet 9g has a shape in which at least the corners on the outer circumferential side are shaved, so the shape is not limited to an isosceles trapezoid, but may also be an isosceles trapezoid in which the outer circumferential side is more inclined than the inner circumferential side. Needless to say, it's a good thing.

When driving the objective lens 9a to perform focus control and tracking control, the objective lens 9a
In order to maintain the orientation parallel to the optical axis, the flange 9d
are two sets of suspension springs 9e arranged in parallel on both the left and right sides at intervals vertically.
and 9f.

As shown in FIG. 9, a total of four pairs of left and right suspension springs 9e and 9f have terminals 9j for attachment at both ends of two elongated elastic plate-shaped conductors 9i arranged in parallel. The lead wire supports the flange 9d and also serves as a lead wire for sending control signals to the focus coil 9b and tracking coil 9c.

Upper and lower suspension springs 9e and 9 on one side
As shown in FIG. base 1
After fixing with adhesive to the projection 10a and flange 9d of 0, the two claws 9k are broken off to electrically separate the upper and lower suspension springs 9e and 9f, thereby making the gluing work easier. Upper and lower suspension springs 9
e and 9f can be attached accurately in parallel.

The two plate-shaped conductors 9i constituting each suspension spring 9e and 9f have different widths (for example, 0.10 mm and 0.12 mm) and have different resonance frequencies.
f is less likely to resonate at a specific frequency, thereby making it less likely that unnecessary resonance will occur.

In addition, in this case, the wider plate-shaped conductor 9i is placed on the outside (that is, on the upper side in 9e, and on the upper side in 9f).
It seems that arranging them separately (at the bottom) has a more pronounced effect.

Furthermore, a damping material 9m made of a viscoelastic material such as butyl rubber or silicone rubber is filled between the two plate-shaped conductors 9i of the suspension springs 9e and 9f, thereby damping the resonance generated in the plate-shaped conductor 9i. I'm starting to let them do it.

The manufacturing process of the suspension spring will be explained 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, with the suspension springs 9e and 9f connected at only a few points around the periphery so that they can be easily separated.

After thoroughly washing this sheet 13, a primer is applied, and as shown in FIG. Vulcanize at 200℃ for 15 minutes and bake 9m of dump material.

The reason why a primer is applied as a pre-treatment is to make it easier for the dump material 9m to adhere.

Dump material 9 by silk screen printing machine 14
When applying m, use a printing brush to touch the plate conductor 9.
This is done by moving it in the longitudinal direction of i.

In addition, 9n of scaly particles (e.g. scaly graphite, scaly graphite,
If mica, etc.) is mixed in, this will strengthen the action as a so-called book damper on the two plate-shaped conductors 9i, increasing the "shear damping" effect.

Furthermore, by employing silk screen printing, the scale-like particles 9n are aligned in the direction of movement of the printing brush (that is, the longitudinal direction of the plate-shaped conductor 9i), as shown in FIG. This further increases the "shear braking" effect.

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

〓Effects of the Invention〓 As explained above, the optical pickup device of the present invention is made of plate-like conductors arranged in parallel and a viscoelastic body filled with scale-like particles mixed between the plate-like conductors. The objective lens is swingably supported by the suspension springs arranged in parallel with each other at vertical intervals on both sides of the objective lens. Since the damping material made of a viscoelastic material mixed with scale-like particles and filled between a plurality of plate-shaped conductors damps the resonance of the plate-shaped conductors, unnecessary resonance of the suspension spring can be suppressed. This makes it possible to prevent adverse effects on the reproduced signal.

Furthermore, if the scale-like particles mixed in the viscoelastic body are aligned in the longitudinal direction of the plate-shaped conductor, the resonance of the plate-shaped conductor can be more effectively damped.

[Brief explanation of drawings]

Fig. 1... A plan view and a front view of an embodiment of the present invention, Fig. 2... A plan view with the cover removed,
Figure 3: An explanatory diagram showing the optical path, Figure 4: A perspective view showing the multi-lens support mechanism, Figure 5: A perspective view of the back cover, Figure 6: An explanatory diagram showing the collimator lens positioning means. , Fig. 7...An exploded perspective view of the actuator, Fig. 8...A plan view showing its arrangement in a CD player, Fig. 9...A plan view of the suspension spring, Fig. 10...One of the suspension springs. Plan view of manufacturing process, 11th
Figure...Side view showing the silk screen printing, Figure 12...Explanatory diagram of the damping agent of the suspension spring 9e, 9f...Suspension spring, 9i...
Plate conductor, 9m...dump material, 9n...scaly particles.

Claims (1)

[Scope of Claims] 1. An objective lens comprising a suspension spring each composed of a plurality of plate-shaped conductors and a damping material made of a viscoelastic material filled between the plate-shaped conductors and mixed with scale-shaped particles. An optical pickup device characterized in that the objective lens is swingably supported by the suspension springs arranged in parallel with each other at a vertical interval on both sides of the lens. 2. The optical pickup device according to claim 1, wherein the scale-like particles mixed in the viscoelastic body are aligned so as to face the longitudinal direction of the plate-like conductor.