JPH0777037B2 - Optical pickup device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a suspension spring that swingably supports an objective lens in an optical pickup device used in a video disc player, a compact disc player or the like. It is a thing.

[Outline of Invention]

In an optical pickup device, an objective lens is swingably supported by four sets of suspension springs for performing focus control and tracking control, and each suspension spring is arranged in parallel and has a plurality of widths different from each other. The plate-shaped conductors are respectively configured so that the resonance frequencies of the plate-shaped conductors are different from each other to prevent unnecessary resonance generated in the suspension spring.

[Conventional technology]

Conventionally, in an optical pickup device, an objective lens is supported by two suspension springs on each side of the objective lens so as to be swingable, and a focus coil and a tracking coil fixed to the objective lens are driven to drive the objective lens to the optical axis. It is known that the focus control and the tracking control are performed by moving the axis parallel to the axis.

However, in such a device, all suspension springs resonate at a specific frequency, which causes a noise to be mixed in a reproduced signal.

[Problems to be solved by the invention]

An object of the present invention is to improve the above-mentioned drawbacks of the conventional device, and to provide an optical pickup device which eliminates the resonance of the suspension spring and prevents the reproduction signal from being adversely affected.

[Means for solving problems]

In order to achieve the above object, the optical pickup device of the present invention is provided with four sets of suspension springs, each of which is composed of a plurality of plate-shaped conductors arranged in parallel and having mutually different widths. The objective lens is swingably supported by the suspension springs, two pairs of which are arranged in parallel at intervals.

[Action]

By doing so, the resonance frequencies of the plurality of plate-shaped conductors forming each suspension spring are different from each other, so that the suspension spring is unlikely to resonate at a specific frequency, and unnecessary resonance of the suspension spring is prevented from occurring, thereby preventing a reproduction signal. Can be prevented from being adversely affected.

〔Example〕

An optical pickup device 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.
The figure shows a base with the actuator 9 integrated.
FIG. 10 is a plan view (partially sectional view) showing a part where 10 is removed.

The optical pickup device is composed of a laser diode 2, a grating 3, a plate prism 4, a collimator lens 5, a triangular prism 6, a multi-lens 7 and a photodetector 8 incorporated in a body 1, and an actuator 9 incorporated in a base 10. ing.

FIG. 3 is an explanatory view showing the optical path, and the triangular prism 6, the objective lens 9a, and the disk D are twisted by 90 ° about the optical axis in the left-right direction in order to display them on the same plane. It is shown in a closed state.

The laser beam emitted from the laser diode 2 is focused by the objective lens 9a reflected by the plate prism 4 and the triangular prism 6 and focused on the signal recording surface of the disc D located above the optical pickup device. The reflected light modulated by the recording 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 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 and emitted from the laser diode 2. The laser beam is reflected by the 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) passes through the plate prism 4. It is sent to the multi-lens 7.

The reflected light from the signal recording surface of the disc D is reflected by the plate prism 4
Is given astigmatism when transmitted through.

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

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

The direction in which astigmatism generated by combining the astigmatism 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 the disc D 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 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 light beam transmitted through the plate prism 4 is correctly incident on the photodetector 8 (with the photodetector 8 fixed) It is designed to perform axis alignment and focus adjustment.

FIG. 4 shows a support mechanism for the multi-lens 7. The multi-lens 7 is fixed in a lens sleeve 7b having a groove 7a in the circumferential direction, and the lens sleeve 7b has a pair of wings 7c. It is supported inside the provided lens base 7d so as to be slidable in the axial direction and not to rotate.

As shown in FIG. 2, the lens base 7d is sandwiched between the pair of wings 7c by the positioning portion 1a of the body 1 and the elastic base retainer 1b, thereby moving in the plane orthogonal to the optical axis. Supported as possible.

The wing portions 7c of the lens base 7d have their tips facing the windows 1c formed on both sides of the body 1, respectively, and at the time of optical axis alignment, the wing portions 7c can be moved from this window 1c by using a jig. The position is adjusted in the plane sandwiched and orthogonal to the optical axis.

When adjusting the focus, the body 1 and lens base
By inserting the eccentric pin from the hole formed on the back surface of 7d and engaging the eccentric pin with the groove 7a of the lens sleeve 7b and rotating the eccentric pin, the position of the lens sleeve 7b in the optical axis direction can be changed. Adjust.

The surface of the plate prism 4 on which the half mirror 4a is provided is adhered and fixed to the positioning portion 1d of the body 1, and the both ends of the plate prism 4 and the surface on the opposite side of the half mirror 4a are spaced with a minute interval. Four protrusions 11a for preventing movement are arranged.

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.

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

For the laser diode 2, attach the shoulder of its base to the mounting hole 1e.
It is positioned by bringing it into contact with the second stepped portion 1g, and the rear surface thereof is pressed and supported by the LD presser 12.

The LD presser 12 has two elastic legs each having an engaging claw 12a at its tip, and these two engaging claws 12a are formed at two corresponding positions on the outer periphery of the protruding portion of the body 1. Are engaged with the respective engaging portions 1h.

When attaching the G holder 3a and the laser diode 2, the G holder 3a, the washer, the G spring 3b and the laser diode 2 are inserted into the attachment hole 1e in this order, and the LD retainer 12 is attached to the rear surface of the base of the laser diode 12. Are pressed against each other and the engaging claws 12a of the two elastic legs are engaged 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 it is damaged, remove the LD claw 12a from the engaging claw 12a of the LD presser 12 to remove the LD presser 12 easily. The diode 2 can be replaced by itself.

The collimator lens 5 is supported by a collimator holder 5a having two legs 5b and 5c on the back surface thereof, and as shown in FIG. 6, the two legs 5b and 5c are circular holes 1i for positioning the body 1. Are respectively fitted to.

The cross-section of the two legs 5b and 5c is perpendicular to the axis, one leg 5b is circular, and the other leg 5c is elliptical or rhombic long in the optical axis direction and short in the direction orthogonal to the optical axis. The legs 5c can be slightly moved in the round hole 1i in the direction orthogonal to the optical axis, which allows the positioning accuracy in the optical axis direction to be kept high while It is designed to allow a certain dimensional error (between the space of () and the space of the round holes).

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

The actuator 9 is integrally incorporated in the base 10, and when the base 10 is attached to the body 1, the objective lens 9a is located above the triangular prism 6.

The positioning of the base 10 with respect to the body 1 is similar to the positioning of the collimator holder 5a shown in FIG.
The method is carried out by fitting the round pin and the rhomboid pin projecting from the above into the round holes provided in the pickup body.

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

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, whereby the pickup P can be made smaller as shown in FIG. 8 for the purpose of downsizing the CD player.
Arrange so that it moves in the diagonal direction of the CD player,
Also, when the outer peripheral side corner of the pickup P on the magnet side is cut obliquely (so as not to hit the wall of the CD player), even if the flange 9d vibrates greatly to the left and right (for tracking), both tracking The coil 9c (the inner vertical portion of the coil 9c) does not come off from the surface of the magnet 9g.

It should be noted that the shape is not limited to the isosceles trapezoid because it is sufficient if at least the outer peripheral side corners of the magnet 9g are carved, and even an unequal leg trapezoid in which the outer peripheral side is more inclined than the inner peripheral side. It goes without saying that it is good.

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 the focus control and the tracking control, the flange 9d is arranged in parallel on both left and right sides thereof with a vertical interval. It is supported by two sets of suspension springs 9e and 9f.

Totally 4 suspension springs 9e and 9f
As shown in FIG. 9, it has a shape in which mounting terminals 9i are provided at both ends of two elastic long and narrow plate-shaped conductors 9i arranged in parallel, respectively, to support the flange 9d and to focus. It is also used as a lead wire for sending a control signal to the coil 9b and the tracking coil 9c.

The upper and lower suspension springs 9e and 9f on one side are integrally manufactured in a shape in which the terminals 9j on both sides of the suspension springs 9e and 9f are connected by two claw portions 9k through narrow connecting portions, respectively, as shown in the figure. During installation, after fixing the terminals 9j on both sides to the projection 10a and the flange 9d of the base 10 respectively, the two claws 9k are broken to electrically separate the upper and lower suspension springs 9e and 9f. And
As a result, the bonding work is facilitated and the upper and lower suspension springs 9e and 9f can be attached accurately in parallel.

The widths of the two plate-shaped conductors 9i forming the suspension springs 9e and 9f are different from each other (for example, 0.10 mm and
0.12 mm) Due to the different resonance frequencies, the suspension springs 9e and 9f are less likely to resonate at a specific frequency, which makes unnecessary resonance less likely to occur.

However, in that case, it seems that the wider plate conductor 9i is arranged outside (that is, in 9e, on the upper side, and in 9f, on the lower side), respectively. Is.

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

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 a full sheet 13 by etching, with the periphery being connected at several points so that they can be easily separated.

After washing this sheet 13 thoroughly, apply a primer and, as shown in Fig. 11, use a silk screen printing machine.
The dump material 9m is applied using a pattern in which only the portion of the dump material 9m is passed by 14, and finally the dump material 9m is baked by vulcanization at a temperature of 200 ° C for 15 minutes.

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

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

In addition, by mixing scale-like particles 9n (for example, scale-like graphite, mica, etc.) having a size of several μm to several tens of μm into the dump material 9m, the so-called two plate-shaped conductors 9i can be obtained. The action as a book damper becomes stronger, and the "shear braking" effect becomes greater.

Furthermore, by adopting silk screen printing,
As shown in FIG. 12, 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), which further increases the “shear braking” effect. .

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

〔The invention's effect〕

As described above, the optical pickup device of the present invention is provided with four sets of suspension springs each constituted by a plurality of plate-shaped conductors arranged in parallel and having mutually different widths, and vertically spaced on both sides of the objective lens. Since the objective lens is swingably supported by the suspension springs arranged in parallel with each other by two sets,
Since the resonance frequencies of the plurality of plate-shaped conductors constituting each suspension spring are different from each other, it becomes difficult for the suspension spring to resonate at a specific frequency. Therefore, unnecessary resonance can be prevented and adverse effects on the reproduction signal can be prevented. It is possible.

[Brief description of drawings]

FIG. 1 ... Plan view and front view of an embodiment of the present invention FIG. 2 ... Plan view with its cover removed FIG. 3 ... Explanatory drawing showing its optical path FIG. 4 ... Supporting mechanism of its multi-lens FIG. 5: Perspective view of its back cover FIG. 6: Explanatory view showing its collimator lens positioning means FIG. 7: Exploded perspective view of its actuator FIG. 8: Plan view showing its arrangement in a CD player 9 ... Plan view of the suspension spring FIG. 10 ... Plan view of one manufacturing process of the suspension spring FIG. 11 ... Side view showing the silk screen printing FIG. 12 ... Explanatory drawing of dumping agent for the suspension spring 9e , 9f …… Suspension spring 9i …… Plate conductor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Shou 59-63826 (JP, U) Seki 59-66927 (JP, U)

Claims (1)

[Claims] 1. A suspension spring comprising four pairs of parallel-arranged plate-shaped conductors having mutually different widths, and two pairs of suspension springs are arranged on both sides of the objective lens in parallel with each other at intervals vertically. An optical pickup device characterized in that the objective lens is swingably supported by the suspension spring.