JPS6236742A - Optical pickup device - Google Patents

Abstract

PURPOSE:To cut the corners at the outer circumferential sides of an actuator without sacrificing the function of a magnetic circuit of the actuator and to minimize the size of a disk layer to the limit, by providing a trapezoidal magnet having the larger width at the side opposite to a coil than the width at the opposite side to the actuator which performs both the focus control and the tracking control. CONSTITUTION:An actuator 9 contains an objective lens 9a, a focus coil 9b, a flange 9d, two pairs of suspension springs 9e and 9f set at the right and left sides respectively and a magnet 9g and a yoke 9h fixed to a base 10. The magnet 9g has a trapezoidal form where the width at the side opposite to the coil 9b is larger than the width at the opposite side. Then a pickup P is set so that it can be shifted toward the diagonal line of a CD player. Thus both tracking coils 9c (inside vertical part) never get out of the surface of the magnet 9g even though the flange 9d has large right-left vibrations in case the corners of the pickup P are cut at the outer circumferential side of the magnet side.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an optical pickup device used in video disc players, compact disc players, and the like.

Summary of the Invention 1 An optical pickup device is disposed so as to move in a diagonal direction of a disc player, and the shape of a magnet of an actuator that drives a coil fixed to an objective lens to perform focus control and tracking control is adjusted to the coil. The width of the opposing side is wider than the width of the opposite side, and the outer circumferential corner of the body on the magnet side is cut obliquely, thereby making it possible to miniaturize the disc player to the utmost. [Prior Art] When an optical pickup device is moved parallel to one side of a disc player, when the pickup moves to the outermost position of the disc, the portion outside the objective lens is moved from the outer periphery of the disc. Because it protrudes, the length of one side of the disc player must be made that much larger than the diameter of the disc. Therefore, the disc player can be further downsized by arranging the optical pickup device so that it moves in the diagonal direction of the disc player and cutting both corners on the outer periphery, but the magnet is large in the corner on the actuator side. There is a limit to how much you can save. If the magnet is made smaller in order to further reduce the corner on the actuator side, the effective range in which the tracking coil can be driven will decrease, and the magnetic flux acting on the focus coil when it moves significantly in the tracking direction will be at the center of the coil width. There is a drawback that when the objective lens holder is distorted, a torsional force is applied to the objective lens holding frame and the objective lens holding frame begins to roll. [Problems to be Solved by the Invention] The purpose of the present invention is to improve the above-mentioned drawbacks of the conventional device. An object of the present invention is to provide an optical pickup device that allows a player to be miniaturized to the utmost. Means for Solving Problem K] In order to achieve the above object, the optical pickup device of the present invention is arranged to move in the diagonal direction of the disc player and drives a coil fixed to the objective lens. The actuator that performs focus control and tracking control is equipped with a trapezoidal magnet whose width on the side facing the coil is wider than the width on the opposite side, and the outer circumferential corner of the body on the magnet side is shaved obliquely. doing.

[Effect]

By doing this, the width of the side of the magnet facing the coil can sufficiently cover the movement width of the tracking coil, and since the outer corner of the body is cut diagonally, it is possible to The size can be minimized. K 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.
The figure is a plan view (partially a partial view) showing the base 10 with the actuator 9 integrated therein removed. The optical pickup device includes a laser diode 2, a grating 3, and a plate prism 4 built into a body 1.
, a collimator lens 5, a triangular prism 6, a multi-lens 7, a photodetector 8, and an actuator 9 built into a base 10. FIG. 3 is an explanatory diagram showing the optical path. In order to display on the same plane, the triangular prism 6, objective lens 9a, and disk D are arranged at 90 degrees centering on the optical axis in the left and right direction in the figure.
It is shown in a twisted 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 has a half mirror 4a made of a thin metal film formed on one surface of a glass plate with parallel planes.
The laser beam emitted from the laser diode 2, which is arranged at an angle of about 45 degrees with respect to the optical axis, is reflected by this half mirror 4a toward the triangular prism 6, and conversely, it is sent from the triangular prism 6 to the disc. The reflected light (modulated by the signal recording surface of D) passes through the plate prism 4 and is sent to the multi-lens 7. The reflected light from the signal recording surface of the disk D passes through the plate prism 4.
Astigmatism is applied when passing through the light. 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 arranged on both sides of the focus detector, and the detection signals of these detectors are detected by the object. lens 9a
It is input to the actuator 9 as a signal for driving f111w. The direction in which astigmatism, which is the combination of astigmatism given by the plate prism 4 and the multi-lens 7, occurs is set so that it faces the direction in which the sensitivity of the focus detector of the photodetector 8 is maximum, and To eliminate the influence of recording track shadows 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 in the plane orthogonal to the optical axis so that the light beam transmitted through the plate prism 4 enters the photodetector 8 correctly (with the photodetector 8 fixed), the light is 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 within a lens sleeve 7b having a groove 7a in the circumferential direction.
is supported in a lens base 7d having a pair of wing portions 7c so as to be able to vibrate in its axial direction but not rotate. As shown in FIG. 2, the lens base 7d has its pair of wing ICs 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 wings 7C of the lens base 7d face windows 1C formed on both sides of the body 1, and when aligning the optical axis, the wing IC is held between the windows 1c using a jig. Then, the position is adjusted within a plane perpendicular to the optical axis. Further, when focusing am, an eccentric bottle is inserted through a hole formed on the back surface of the body 1 and the lens base 7d, and the eccentric bottle is engaged with the groove 78 of the lens sleeve 7b and rotated. Adjustment is made by changing the position of the lens three 77b in the optical axis direction. The plate prism 4 is adhesively fixed to the positioning portion 1d of the body 1 on the surface 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.
Used for temporary positioning when installing. As shown in FIG. 2, a G holder 38 that supports the grating 3 and the laser diode 2 are mounted in a 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 the G holder 3a is positioned between the rear surface and the base of the laser diode 2.
It is pressed forward by a spring 3b and supported so as to be rotatable and adjustable around the optical axis. Laser diode 2 is mounted on the shoulder of its base through hole 1.
It is positioned by coming into contact with the second step 1g in e, and its eroded surface is pressed and supported by the LD presser 12. The LD presser 12 has two elastic legs each having an engaging claw 12a at the tip thereof. are engaged with the engaging portions 1h, respectively. When installing the G holder 3a and the laser diode 2, insert the G holder 3a1 washer, G spring 3b, and laser diode 2 into the hole 1e in this order, and attach the LD holder to the back of the base of the laser diode 2. 12 are brought into contact and pressed, and the engaging claws 1 of the two elastic legs are pressed.
2a 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 engaging claw 1 of the LD presser 12
2a from the engaging portion 1h of the body 1 and removing the LD presser 12, the radar diode 2 can be easily replaced as a single unit. The collimator lens 5 has two wooden legs 5b and 5C on the back side.
As shown in FIG. 6, the two collimator holders 1115b and 5C are fitted into positioning round holes 11 of the body 1, respectively. The shape of the cross section perpendicular to the axis of the two legs 5b and 5C is
One of the legs 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 orthogonal to the optical axis, and the leg 5G has an optical axis inside the round hole 11. It can be moved slightly in the orthogonal direction, allowing for some dimensional error (between the leg spacing and the round hole spacing) in the direction orthogonal to the optical axis while maintaining high positioning accuracy in the optical axis direction. It looks like this. FIG. 7 shows 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 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 performed by fitting the round bottles and diamond bottles protruding from the base 10 into round holes provided in the pickup body, 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 9a1, a focus coil 9b, and two tracking coils 9G are fixed, and a flange 9d attached to a protrusion 10 of a base 10.
It is comprised of two sets of suspension springs 9e and 9f on each of the left and right sides that are swingably supported on the base 10, a magnet 9g fixed to the base 10, and a yoke 9h. The magnet 99 has a trapezoidal shape in which the width on the side facing the coil is wider than that on the opposite side.Thereby, in order to make the CD player smaller, as shown in FIG. If the outer corner of the pickup P on the magnet side is cut diagonally (to avoid hitting the wall of the CD player), the flange 9d will move in the direction of (for tracking). Both tracking coils 9 even if they vibrate left and right.
C (inner vertical portion) does not come off the surface of the magnet 99. Note that it is sufficient that the magnet 90 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. In order to keep the attitude of the objective lens 9a parallel to the optical axis when driving the objective lens 9a to perform focus control and tracking control, the flanges 9d are arranged in parallel with each other at intervals vertically on both the left and right sides of the flanges 9d. It is supported by two sets of suspension springs 9e and 9f. A total of 4 sets of suspension springs 9C and 9F on the left and right sides
As shown in FIG. 9, the flange 9 has a shape in which terminals 9j for attachment are provided at both ends of two elongated elastic plate-shaped conductors 91 arranged in parallel.
d and also serves as a lead wire for transmitting control signals to the focus coil 9b and the tracking coil 9C. As shown in the figure, 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 thereof are connected by two claw portions 9k through narrow connection portions. When installing, after adhesively fixing the terminals 9j on both sides to the protrusion 10a and flange 9d of the base 10, the two claws 9k are broken off to electrically separate the upper and lower suspension springs 9e and 9f. This facilitates the bonding work and allows the upper and lower suspension springs 9e and 9f to be attached accurately in parallel. The two plate-shaped conductors 91 constituting each suspension spring 9e and 9f have different widths (for example, 0
．． 10a+m and 0.12mm), the suspension springs 9e and 9f are less likely to resonate at a specific frequency, which makes unnecessary resonance less likely to occur. It seems that placing the wider plate-shaped conductor 91 on the outside (that is, on the upper side in 9e and on the lower side in 9f) has a more pronounced effect. A damping material 91Il made of a viscoelastic material such as butyl rubber or silicone rubber is filled between the two plate-shaped conductors 91 9e and 9f, so as to attenuate the resonance generated in the plate-shaped conductor 91. The manufacturing process of suspension springs will be explained with reference to Figures 10 and 11. Suspension springs 9e and 9'' are connected at only a few points around the periphery so that they can be easily separated. , a large number of sheets are simultaneously formed on a single sheet 13 by etching. This sheet 13 is thoroughly washed (afterwards) a brimer is applied, and as shown in FIG. Apply 9m of dump material using a pattern that only passes through the parts, and finally vulcanize at a temperature of 200℃ for 15 minutes to bake the 9m of dump material.Brimer is applied as a pretreatment to dump material 91.
This is to make it easier to adhere. When applying the dump material 91 using the silk screen printer 14, a printing brush is moved in the longitudinal direction of the plate-shaped conductor 91. In addition, if 9n of scale-shaped particles (for example, scaly graphite, mica, etc.) with a size of several micrometers to several tens of micrometers are mixed into the dump material 9, two plate-shaped conductors can be formed. 91
The effect of the so-called book damper becomes stronger, and the "shear damping" effect becomes larger. Furthermore, by using silk screen printing,
As shown in FIG. 12, the scale-like particles 9n are distributed in the moving direction of the printing brush (that is, in the longitudinal direction of the plate-shaped conductor 91).
Since they are aligned facing the same direction, the "shear damping" effect becomes even greater.・In addition, in the above embodiment, each suspension spring 9e
Although the number of plate-shaped conductors 91 constituting ``and 9'' is two, it is not limited to this, and the number may be three or more.

【Effect of the invention】

As explained above, the optical pickup device of the present invention is arranged to move in the diagonal direction of the disc player, and drives the coil fixed to the objective lens to perform focus control and tracking. Equipped with a trapezoidal magnet whose width on the side facing the coil is wider than the width on the opposite side, and the outer corner of the body on the magnet side is shaved off diagonally to improve the function of the actuator's magnetic circuit. The outer corner can be cut without sacrificing the size of the disc player, and the size of the disc player can be reduced to almost the disc size.

[Brief explanation of drawings]

Fig. 1: A plan view and front view of an embodiment of the invention Fig. 2: A plan view with the cover removed Fig. 3:
...An explanatory diagram showing the optical path.FIG. 4.A perspective view showing the multi-lens support mechanism.FIG. 5.A perspective view of the back cover.FIG. 6.An explanation showing the collimator lens positioning means. Figure 7: Exploded perspective view of the actuator Figure 8:
...A plan view showing the arrangement of the CD player in Figure 9.A plan view of the suspension spring in Figure 10.A plan view of one manufacturing process of the suspension spring.Fig. 11. Side view showing silk screen printing FIG. 12...Explanatory diagram of the damping agent of the suspension spring 9...Actuator 9a...Objective lens 9b
...Focusing coil 9C...Tracking coil 9d...Flange 99...Magnet 9
h...Yoke

Claims (1)

[Claims] (a) An actuator arranged to move in a diagonal direction of the disc player, and (b) an actuator that drives a coil fixed to an objective lens to perform focus control and tracking control, and is arranged to face the coil. An optical pickup device comprising a trapezoidal magnet whose width on one side is wider than the width on the opposite side, and (c) the outer corner of the body on the magnet side has a shape cut diagonally.