JPS6236750A - Optical pickup device - Google Patents

Abstract

PURPOSE:To attain a compact and light-weight design of a half mirror as well as to simplify the assembling work of the half mirror, by setting a plate prism containing a half mirror on its single side at about 45 deg. against the optical axis and providing the shift preventing projections at both end and on the other side of the prism with microspaces secured among them. CONSTITUTION:A plate prism 4 contains a half mirror 4a of a metallic thin film formed on a single side of a glass plate having planes parallel with each other. Then the prism 4 is set at about 45 deg. against the optical axis and the laser beam radiated from a larser diode 2 is reflected by the mirror 4a toward a triangular prism 6. The prism 4 is adhered fixedly to a positioning part 1d of a body 1 at the side where the mirror 4a is provided. Then four pieces of shift preventing projections 11a are provided at both ends of the prism 4 and on the other side of the mirror 4a with microspaces secured among them. These projections 11a is included in a rear cover 11 and used for the temporary positioning purpose when the prism 4 is attached to the body 1.

Description

[Detailed description of the invention] [Industrial application field 1]. The present invention relates to an optical pickup device used in video disc players, compact disc players, and the like. Summary of the Invention It is fixed with adhesive to the positioning part of the body, and protrusions for preventing movement are arranged at minute intervals on both ends and the other surface of the plate prism, and during assembly, the protrusions for preventing movement are used as temporary It is designed to be used as a positioning member. [Prior art 1] Conventionally, in an optical pickup device, a laser beam emitted from a laser diode is reflected toward a collimator lens, and the reflected light from a disk signal recording surface is transmitted toward a photodetector. A half mirror made of two triangular prisms bonded together is used. However, such a bonded prism has the disadvantage that it is large and heavy, which hinders the reduction in size and weight of the optical pickup device, and that it is difficult to fix to the body and takes time and effort to assemble. [Problems to be Solved by the Invention K] The purpose of the present invention is to improve the drawbacks of the above-mentioned conventional devices. Means for Solving Problem K] In order to achieve the above object, the optical pickup device of the present invention is formed by forming a half mirror on one surface of a glass plate having parallel planes. A plate prism is arranged at an angle of about 45° with respect to the optical axis, the one surface of the plate prism is adhesively fixed to the positioning part of the body, and a minute interval is placed between both ends and the other surface of the plate prism. K effect] By doing this, the half mirror can be made smaller and lighter, and during assembly, the protrusion for preventing movement can be used as a temporary part of the plate prism. It can be used as a positioning member, and the assembly is I!I 111. [Example and a front view, and also a second
The figure is a plan view (partial view) showing the state where the base 10 in which the actuator 9 is integrated is 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.
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 is focused on the disk D located above the optical pickup device. The reflected light that is converged on the signal recording surface and 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 has a half mirror 4a made of metal 7IJyi4 formed on one surface of a glass plate with parallel planes, and is arranged at an angle of about 45'' with respect to the optical axis. The emitted 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) 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). y1 Change the convergence position of the passing 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. lens 9a
The signal is input to the actuator 9 as a drive control signal. 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. The light beam that passed through the plate prism 4 is Fo!・The light enters the detector 8 correctly.) 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 (while keeping the photodetector 8 fixed), the optical axis and focus are adjusted. It is now possible to do this. 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 1d having a pair of four parts 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 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 wing portions 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 portions 7C are inserted through the windows 1C using a jig. The position ei is adjusted 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 1d, and the eccentric pin is engaged with the groove 78 of the lens sleeve 7b and rotated. This changes and adjusts the position of the lens sleeve 7b 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 19 in e, and its rear 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 3a, washer, G spring 3b, and laser diode 2 into the hole 1e in this order, and attach the LD to the rear surface of the base of the laser diode 2. The presser foot 12 is 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 remove the LD presser 12, the laser diode 2 can be easily attached to the
Can be replaced in one piece. The collimator lens 5 is supported by two collimator holders 5a, 1lI5b and 5Ci1', on the back side, and its two wooden legs 5b and 5 are supported as shown in FIG.
C 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 wooden legs 5b and 5C is
One leg 5b has a circular shape, and the other leg 5C has an elliptical or diamond shape that is long in the direction of the optical axis and short in the direction orthogonal to the optical axis, and the leg 5C is shaped like an optical axis within the round hole 11. It can be moved slightly in the orthogonal direction, which allows for a certain degree of 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 is supposed to be done. FIG. 7 shows an exploded perspective view of the actuator 9 which 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 relative to the body 1 is similar to the positioning of the collimator holder 5a shown in FIG. It is done in a way that fits. 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 a projection 10 of a base 10 that connects the flange 9d.
It is composed of two sets of suspension springs 9e and 9t on the left and right, which are swingably supported on the base 10, and a magnet 9g and a yoke 9h fixed to the base 10. The magnet 9g has a trapezoidal shape in which the width of the sword facing the coil is wider than that of the opposite side, so that the pickup P is placed on the diagonal of the CD player as shown in FIG. 8 in order to downsize the CD player. If the outer corner of the magnet side of the pickup P is cut diagonally (to avoid hitting the wall of the CD player), the 7 lunge 9d will move in the direction of (for tracking). ) Even if there is a large vibration left or right, both tracking coils 9
C (inner vertical part) is designed so that it does not come off from the magnet 9g. Note that it is sufficient to have a shape in which at least the corners on the outer circumference side of the magnet 9 are shaved, so the shape is not limited to an isosceles trapezoid, but may be an isosceles trapezoid in which the outer circumference side is more inclined than the inner circumference side. But it goes without saying that 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 9e and 9f on the left and right sides
As shown in FIG. 9, it has a shape in which terminals 9j for attachment are provided at both ends of two elongated wooden plate-like conductors 91 each having elasticity arranged in parallel, and a flange 9.
d and also serves as a lead wire for sending an Ill ill signal 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 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 9r. 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 9r have different widths (for example, 0
．． 10111 and 0.12mm) Due to the resonance frequency being n, the suspension springs 9e and 9r are less likely to resonate at a specific frequency, and this may cause problems. j5 resonance is less likely to occur. In addition, in this case, it seems that placing the wider plate-shaped conductor 91 on the outside (that is, on the upper side in 9C and on the lower side in 9F) will have a more pronounced effect. It is. Furthermore, 9 ml of damping material made of a viscoelastic material such as butyl rubber or silicone rubber is filled between the two plate-shaped conductors 91 of the suspension springs 9e and 9'', thereby damping 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 9f are connected at only a few points around the periphery so that they can be easily separated. In this state, a large number of etches are simultaneously formed on one sheet 13 by etching.This sheet 13 is thoroughly washed and coated with a primer, and as shown in FIG. Apply dump material 9- using a pattern that passes only the 9I11 part, and finally
The dump material 91 is baked by vulcanization at 00° C. for 15 minutes. Dump material 9I is coated with brimer as a pre-treatment.
This is to make it easier for I to adhere. When applying the dump material 9m using the silk screen printer 14, a printing brush is moved in the longitudinal direction of the plate-shaped conductor 91. In addition, if scale-like particles 9n (for example, scaly graphite, porridge, etc.) having a size of several micrometers to several tens of micrometers are mixed into the dump material 9-, the two plate-shaped conductors 91 It acts as a so-called book damper against the paper, increasing the "slip braking" effect.Furthermore, by using silk screen printing,
As shown in FIG. 12, the scale-like particles 9n are arranged in the direction of movement of the printing brush (that is, in the longitudinal direction of the plate-shaped conductor 91).
Since they are aligned facing toward each other, the [slip braking 4 effect] becomes even greater. In addition, in the above embodiment, each suspension spring 9e
Although the number of plate-like conductors 91 constituting ``and 9'' is set to two, it is not limited to this and may be three or more.K Effects of the Invention] As explained above, The optical pickup device of the present invention has a plate prism formed by forming a half mirror on one side of a glass plate with parallel planes, at approximately 45° with respect to the optical axis.
°The plate prism was arranged at an angle, one surface of the plate prism was adhesively fixed to the positioning part of the body, and protrusions for preventing movement were arranged at small intervals on both ends and the other surface of the plate prism. As a result, the half mirror can be made extremely small and lightweight, and the protrusion for preventing movement can be used as a temporary positioning member for the plate prism during assembly, making assembly easy. be.

[Brief explanation of the drawing]

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:
・・Plan view showing its arrangement in a CD player FIG. 9 ・Plan view of the suspension spring FIG. 10 ・・Plan view of one manufacturing process of the suspension spring FIG. 11 ・・Silk screen of the suspension spring TM side view showing printing Figure 12...Explanatory diagram of the damping agent of the suspension spring

Claims (2)

[Claims] (1) A plate prism formed by forming a half mirror on one side of a glass plate with parallel planes at approximately 45 mm with respect to the optical axis.
° The one surface of the plate prism is adhesively fixed to the positioning part of the body, and protrusions for preventing movement are arranged at minute intervals on both ends and the other surface of the plate prism. An optical pickup device featuring: (2) Claim 1, characterized in that the protrusion for preventing movement is provided protrudingly on the back cover that covers the back surface of the body.
The optical pickup device described in Section 1.