JPH0470701B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a pickup device in an optical recording/reproducing device.

BACKGROUND ART Disks such as video disks and digital audio disks, which are information recording media, are
The information signal is recorded by forming minute pits (indentations) corresponding to the information signal as spiral tracks on its surface. When reading an information signal recorded in this manner, a fine spot light is irradiated onto the track, and changes in reflected light depending on the presence or absence of pits are converted into electrical signals and reproduced as the original information signals.

Various pick-up devices for reading information signals have already been developed, and specifically, they include a light emitting element such as a laser diode, an objective lens that focuses the irradiation light emitted by the light emitting element on the disk surface as a spot light, and a light emitting element such as a laser diode. a light-receiving element that ultimately receives the reflected light from the disk recording surface and emits the electric signal; and a light-receiving element that transmits the irradiated light from the light-emitting element, bends the reflected light with respect to the irradiated light, and guides it to the light-receiving element. A beam splitter, a wavelength plate that changes the polarization direction of the light by 1/4 wavelength in order to separate the irradiated light and reflected light by the beam splitter, and a wavelength plate that changes the polarization direction of the light by 1/4 wavelength to separate the irradiated light and reflected light, and a wavelength plate that uses the irradiated light for RF signal and focus servo and a cylindrical lens that cooperates with the light receiving element to obtain a signal for focus servo. Note that the focus servo is a position control of the objective lens in the optical axis direction, which is performed to focus the irradiated light as a spot light on the disk recording surface. Tracking servo refers to position control of the irradiated light in the disk radial direction, which is performed to cause the spot light to accurately track the recording track.

In recent years, disk players have been becoming smaller in size so that they can be easily carried around for enjoying outdoor performances, or to be installed in automobiles, etc., and there has been a desire for smaller pickup devices.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and its object is to provide a pick-up device that is easy to downsize and has good assemblability.

A pickup device according to the present invention includes a fixed optical system including a plurality of optical elements including a wavelength plate, a base member supporting the wavelength plate, a holding member holding each optical element and the base member, an objective lens and It has a movable optical system that includes a drive mechanism that servo drives the objective lens and is coupled to the fixed optical system, and the base member is held between the holding member and the drive mechanism. .

Embodiments Hereinafter, a pickup device as an embodiment of the present invention will be described with reference to the accompanying drawings.

As shown in FIGS. 1 to 6, the pick-up device has a pick-up body 1 which is a holding member. The pick-up body 1 is made of aluminum, its alloy, or synthetic resin, and has a through hole 1a as shown in FIG. A laser diode 3 as a light emitting element, a grating (diffraction grating) 4, a beam splitter 5, and a collimator lens 6 are coaxially arranged in the through hole 1a. The grating 4 is for splitting the irradiation light emitted from the laser diode 3 into light for focus servo for reproduction RF signal requirements and light for tracking servo. It transmits the irradiated light and bends the reflected light from the recording surface of the disk, which will be described later, with respect to the irradiated light, and guides it to a light receiving element, which will be described later. Further, the collimator lens 6 is for converting the irradiated light into parallel light.

Among the optical elements mentioned above, the laser diode 3, the grating 4, and the beam splinter 5
are supported on cylindrical holders 7, 8, and 9 such that the optical axes of these three optical elements coincide with the central axis of each holder, and each holder has a through hole 1a as a holder insertion hole. They are stacked and inserted inside. The through hole 1a has a circular cross section perpendicular to its central axis, and therefore each holder 7, 8, and 9 is movable along the central axis of each holder and rotated about the central axis. It is now possible to move. However, the holder 7 is fixed to the pick-up body 1 with screws. As is particularly clear from FIG. 7, a wave-shaped washer 11 or a coil spring 12, which is an elastic member, is interposed between each holder 7, 8, and 9, respectively.

The two holders 7 and 9 located at both ends of the stacked holders 7, 8, and 9 have their respective outer peripheries engaged with the receiving surfaces 1b and 1c provided on the pick-up body 1, so that the through holes are formed. It is positioned in the insertion direction into 1a. A cylindrical sleeve 14 is tightly fitted onto a holder 8 which is located intermediately between the holders 7 and 9. One axial end of the sleeve 14 engages with a receiving surface 7a provided on the holder 7, thereby restricting movement of the sleeve 14 in the direction toward the holder 7. A wall portion 14b in which a light passage hole 14a is formed is provided at the other end of the sleeve 14 in the axial direction, and when the wall portion comes into contact with the axial end of the holder 8, the insertion direction of the holder is (into the through hole 1a). That is, the sleeve 14 acts as a positioning member for the holder 8 located in the middle.

Here, the characteristics each of the holders 7, 8, and 9 and the sleeve 14 have will be explained.

First, there is a holder 7 that supports a laser diode 3 as a light emitting element, and the holder supports the laser diode 3 by press-fitting the laser diode 3 into the inner circumferential surface 7b of one end in the axial direction. . A wall portion 7d in which a pupil 7c is formed is integrally formed at the other end of the holder 7 in the axial direction. In this way, by forming the pupil 7c integrally with the holder 7, the positional accuracy of the pupil with respect to the laser diode 3, which is press-fitted into the holder with high precision, is improved, especially in the plane perpendicular to the irradiation optical axis. The positional accuracy of the laser diode 3 is improved, and the irradiation light emitted from the laser diode 3 can be cut in a state extremely close to a perfect circle centered on its optical axis.

Next, the holder 8 carrying the grating 4 and the sleeve 14 fitted into the holder will be explained. The grating 4 is bonded to the axial end of the holder 8. The inner diameter of the light passing hole 14a formed in the sleeve 14 is larger than the outer diameter of the grating 4, so that the laser diode 3, holder 7, holder 8, wave-like washer 11, and sleeve 14 can be connected to each other. It becomes possible to adhere the grating 4 after small assembly. Therefore, the adhesiveness of the grating 4 becomes stable.
Further, the outer surface 4a of the grating 4 supported by the holder 8 is located inside the outer surface 14c of the wall portion 14a of the sleeve 14. Therefore, when gluing and fixing the grating 4 after the above-mentioned holder 7 etc. have been assembled,
Since external objects are prevented from coming into contact with the grating 4 after adhesion, the grating will not be damaged, and the adhesion of the grating 4 will be more stable, allowing for high precision. .

A centering guide portion 9a that fits into the center hole of the corrugated washer 12 is formed in the holder 9, which is positioned to sandwich the holder 8 together with the holder 7.
By providing this centering guide portion 9a, the wavy washer 12 is accurately positioned with respect to the respective central axes of the holder 9 and the sleeve 14, and due to the pressing force of the wavy washer, the rotation of the holder 9 is prevented. The resistance force generated against the holder becomes uniform around the central axis of the holder, and the holder rotates smoothly. In addition, a holder 8 carrying a grating 4 is also provided.
Similarly to the holder 9, the holder 9 will rotate if a rotational force that exceeds the resistance force caused by the pressing force of the wavy washer 11 is applied. Note that since a sleeve 14 fixed to the pick-up body 1 via the holder 7 is interposed between the holders 8 and 9, when one of the two holders is rotated, the rotational force is It has no effect on the other.

FIGS. 8a to 8f are diagrams for clarifying the overall shape of the pick-up body 1. As shown in FIGS. For example, four adjustment jig insertion holes 1d, 1e, 1f, and 1g are provided for this purpose. Two adjustment jig insertion holes 1d and 1e are provided corresponding to the holder 9 that supports the beam splitter 5. As shown in FIG. 7, the beam splitter 5 has two optical axes 5a and 5b, and one adjustment jig insertion hole 1d has its central axis aligned with a plane that includes these two optical axes. It is formed to be vertical. Further, the other adjustment jig insertion hole 1e is formed parallel to the plane. The remaining two adjustment jig insertion holes 1f and 1g are formed parallel to the adjustment jig insertion hole 1d, and the adjustment jig insertion hole 1f corresponds to the holder 8 holding the grating 4.
Further, an adjustment jig insertion hole 1g provided near the end of the pick-up body 1 is positioned to accommodate a cylindrical holder carrying a multi-lens, which will be described later.

A predetermined adjustment jig (not shown) is inserted into each of these adjustment jig insertion holes 1d to 1g, and the tip of the adjustment jig is engaged with each holder 8, 9, etc. The holders, and thus the optical elements respectively supported by the holders, are rotated and their positions are adjusted. In addition, each adjustment jig insertion hole 1d to 1g is
Their inner diameters are different from each other.

As is clear from FIG. 1, the collimator lens 6 disposed above the beam splitter 5 is directly attached to the pick-up body 1, and furthermore, the outer refractive surface of the collimator lens is lower than the surface of the pick-up body 1. It is also located on the inside. The collimator lens 6 is bonded to the pick-up body 1 with an adhesive. As shown in FIGS. 8a, b, and d, the pick-up body 1 is provided with an adhesive reservoir 1h outside the adhesive surface of the collimator lens. Due to the action of this adhesive reservoir 1h and the capillary phenomenon between the bonding surfaces, the adhesive can be stably supplied to the bonded portion in just the right amount and in excess, and stable adhesiveness can be obtained.

As shown in FIGS. 1 and 8b, a guide hole 1i is formed in the pick-up body 1 on the side of the beam splitter 5, extending perpendicularly to the through hole 1a and communicating with the through hole. ing. A plate-shaped light receiving element 16 is attached to the open end of the guide hole 1i. As is particularly clear from FIG. 3, the light-receiving element 16 is supported on a plate-shaped base member 17, and the base member includes an L-shaped pressing spring 18 and a screw 1 screwed into the pick-up body 1.
It is attached to the pickup body 1 by means 9a and 19b. A pair of screws 19b located at both ends of the L-shaped pressure spring 18 are attached to the base member 17.
The base member 17, and therefore the light receiving element 16, can be positioned in a plane perpendicular to its optical axis by loosening the screw 19b. It's becoming like that. As shown in FIG. 1, a recess 17b is provided in the main surface of the plate-shaped base member 17, and the light receiving element 16 is bonded within the recess. In this case, the shape of the recess 17b is rectangular, and this shape enables positioning of the light receiving element 16 in a plane perpendicular to its optical axis. This allows extremely accurate positioning of the light receiving element 16. Further, the area of the recess 17b is larger than the main surface area of the light receiving element 16, and this surplus area also serves as an adhesive reservoir.
With this configuration, the adhesive can be stably supplied to the adhesive portion without excess or deficiency, and stable adhesiveness can be obtained.

Guide hole 1i provided in pick-up body 1
A cylindrical holder 21 holding a multi-lens 20 such that the optical axis of the multi-lens coincides with its central axis is fitted inside. The diameter of the holder 21 is formed to be slightly smaller than the inner diameter of the guide hole 1i, so that the holder 21 can freely slide in the direction of the central axis of the holder, that is, along the optical axis of the multi-lens 20. It is rotatable around the optical axis. Note that the multi-lens 20 has a combined effect of a so-called cylindrical lens and a normal convex lens.

As shown in FIGS. 6 and 8c and f, the pick-up body 1 is provided with a counterbore portion 1k extending perpendicularly to the guide hole 1i, and the bottom surface of the counterbore portion is provided with a guide hole. A long hole 1l communicating with 1i is formed. The long axis of the long hole 1l is the guide hole 1.
It is formed to be parallel to i. As is particularly clear from FIG. 9, a screw 23 is inserted into the counterbore portion 1k together with a washer 23a and a wavy washer 23b which is an elastic member, and the threaded portion of the screw is inserted into a neck sleeve 23c and has a long length. It is screwed into the holder 21 through the hole 1l. Further, the head of the screw is in contact with the edge of the elongated hole 1l via a washer 23a and a wavy washer 23b. That is, the holder 21 is movable relative to the pick-up body within the range in which the neck sleeve 23c circumscribing the screw 23 can move within the elongated hole 1l.
In addition, these elongated holes 1l, screws 23 and wave-like washers 2
3b, neck sleeve 23c, etc., constitute a fixing mechanism for fixing the holder 21 to the pick-up body 1.

An annular groove 21a is formed on the outer periphery of the holder 21, and the adjustment jig insertion hole 1g provided near the end of the pick-up body 1 corresponds to this annular groove 21a. This adjustment jig insertion hole 1g and long hole 1
1 are spaced from each other at a predetermined angle, approximately 180° in this case, with respect to the central axis of the holder 21. The mutual separation angle of the adjustment jig insertion hole 1g and the elongated hole 1l about the central axis of the holder 21 is approximately 0.
In this case, it becomes necessary to shift the adjustment jig insertion hole and the long hole from each other along the central axis of the holder 21,
In this configuration, the holder 21 becomes large, leading to an increase in the size and cost of the entire pickup device. This problem has been resolved.

As shown in FIG.
A wave plate 25 formed into a rectangular plate shape is disposed above the wave plate 25 , and is supported by a plate-shaped base member main body 27 via a holder 26 . However, the holder 26 constitutes the entire base member together with the base member main body 27. Further, the base member main body 27 is held by the pick-up body 1. Note that the wavelength plate 25 is the laser diode 3 described above.
This is for changing the polarization direction of the light in order to use the beam splitter 5 to separate the irradiation light emitted from the disc recording surface and the reflected light from the disk recording surface.

Here, the holder 26 and the base member main body 27 will be explained based on FIGS. 10 and 11.

First, the holder 26 is formed into a disk shape as a whole, as shown in FIGS. 10a to 10c. A counterbore portion 26a into which the wavelength plate 25 is inserted is provided on the main surface of the holder 26, and the wavelength plate is bonded to the bottom surface of the counterbore portion with an adhesive. This counterbore portion 26a has an arcuate portion 26b.
is formed so that not only a rectangular wave plate 25 but also a circular wave plate can be inserted. Further, in the case of the rectangular wave plate 25, in the case of a wave plate in which the arcuate portion 26b is formed in a circular shape, the four corners of the counterbore portion 26a serve as adhesive reservoirs.

As shown in FIGS. 11a to 11d, the base member main body 27 has two protrusions 26d protruding from the outer periphery of the holder 26 in opposite directions, which fit into each other to support the holder. Two support protrusions 27a are recessed. The holder 26 is slidable relative to the base member main body 27 and within a plane perpendicular to the optical axis of the wave plate 25. As is clear from FIGS. 11a and 11c, the center hole 27b of the base member main body slidably contacts the outer periphery 26e of the holder 26, so that when the holder slides and rotates, the holder It is prevented from shifting in the direction.

On the other hand, an arm portion 26f is provided on the outer peripheral portion of the holder 26 and projects in the radial direction of the holder, and the tip portion of the arm portion is bent at a right angle. As shown in FIG.
6g is exposed to the outside through an opening 1m formed in the pickup body 1. That is, by operating this bent portion 26g with your fingers,
The angular position of the holder 26 and therefore the wave plate can be adjusted.

The above-mentioned pick-up body 1, laser diode 3, grating 4, beam splitter 5, collimator lens 6, cylindrical holders 7, 8 and 9, corrugated washers 11 and 12, and cylindrical sleeve 14, The light receiving element 16, the plate-shaped base member 17, the multi-lens 20, the cylindrical holder 21, the above-mentioned fixing mechanism including the wave-shaped washer 23b, the screw 23, etc., the wavelength plate 25, the holder 26, and the plate-shaped base member The main body 27 and peripheral small members related thereto constitute a fixed optical system.

As shown in FIG. 1, an objective lens 30 is arranged above the wavelength plate 25 to focus the irradiation light emitted from the laser diode 3 onto the recording surface of the disk 29 as a spot light.
A cylindrical lens pad 30a is fitted around the outer periphery of the objective lens 30. The objective lens 30 is fitted into the upper end of a lens holder 31, which is a first holding member formed into a substantially cylindrical shape, so that its optical axis coincides with the central axis of the lens holder. As shown in FIGS. 12 and 13, the lens holder 3
A focusing coil 3 is installed on the outer periphery of the lens 1 so that the center axis of the coil coincides with the optical axis direction of the objective lens 30.
2 is wrapped. Note that a counterweight 30b is attached to the lower end of the lens holder 31. The lens holder 31 has a total of four overhangs, each pair of which protrude in a direction perpendicular to the optical axis direction of the objective lens 30 and in opposite directions about the central axis of the lens holder, on both ends of the lens holder 31 in the central axis direction. 31a and 31b are provided. One of each pair of protruding parts 31a and 31b is opposed to each other in the direction of the central axis of the lens holder 31. A bobbin 34 having a rectangular cross section is attached between the two opposing overhangs 31a and 31b. A tracking coil 35 is wound around the outer periphery of the bobbin 34 so that the center axis of the coil coincides with a direction perpendicular to the optical axis direction of the objective lens 30. This tracking coil 35 is called a second coil, whereas the focusing coil 32 is called a first coil. Further, the lens holder 31 and the bobbin 34 are respectively referred to as a first holding member and a second holding member.

Two overhangs 31 with bobbins 34 attached
The other two projecting portions 31a and 31b protruding in the opposite direction to the projecting portions 31a and 31b include a pair of flexible projecting portions that are spaced apart and parallel to each other in the optical axis direction of the objective lens 30 and are flexible in that direction. One end of each leaf spring 36, which is a flexible member, is connected. The other end of each leaf spring is connected to a relay member 37. That is,
Each leaf spring 36 is attached to the relay member 37 in the form of a cantilever. Connected to the relay member 37 are respective one ends of a pair of leaf springs 38, which are a pair of flexible members arranged parallel to and apart from each other in a direction perpendicular to the optical axis direction of the objective lens 30 and flexible in the direction. ing. The other ends of the pair of leaf springs 38 are connected to a base member 39. That is, each leaf spring 38 is attached to the base member 39 in a cantilevered manner.

These lens holder 31, bobbin 34, leaf spring 36, relay member 37, leaf spring 38, base member 39, and peripheral small members related to these allow the objective lens 30 to be A support mechanism is configured to support the objective lens so that it is movable in the optical axis direction and in a direction perpendicular to the optical axis direction, and so that the optical axis of the objective lens is perpendicular to the recording surface of the disk 29.

Here, the relay member 37 and each leaf spring 36 and 38
The state of connection with is explained in detail.

The leaf springs 36 and 38 and the relay member 37 are bonded to each other with an adhesive. The relay member 37 has a protrusion 37a that protrudes from the adhesive surface with each leaf spring.
is formed. Further, as is particularly clear from FIG. 12, the relay member 37 has an escape groove 37 for the adhesive between the adhesive surface with the leaf spring 36 and the protrusion 37a.
b is formed. When bonding each leaf spring 36 and 38 to the relay member 37, the protrusion 37a is held by a predetermined jig (not shown), and an escape groove 37b for the adhesive is provided. This prevents the adhesive from flowing into the jig, etc., and prevents the relay member 37 and the jig, etc. from being glued together.

Next, the state in which the base member 39 is fixed to the pickup body 1 will be described in detail.

As shown in FIGS. 4, 12, and 13, the base member 39 is elongated (and bent into a substantially L-shape), and has screws 39a,
It is fixed to the pickup body 1 by 39b. In particular, the screw 39b is attached to the proximal end of the pair of leaf springs 36 and 38 mentioned above.
It is located near the fixed end of, in this case, between a pair of leaf springs 38. The lower surface of the base member 39 is attached to the upper surface of the pick-up body 1 by engaging with the edge of a rectangular recess 1n (see FIG. 8d) formed on the upper surface of the pick-up body 1. A positioning protrusion 39c for positioning 39 is formed. As a result, the positional accuracy of the base member 39 with respect to the pickup body 1 is extremely improved.

As shown in FIGS. 4 and 12, the same poles are arranged to face each other in a direction perpendicular to the optical axis direction of the objective lens 30 and a direction perpendicular thereto, and the focus is set between the opposing poles. A pair of magnets 41 are arranged to sandwich the single coil 32 and tracking coil 35. These pair of magnets 41 are magnetically coupled by a yoke 42 that is generally U-shaped as a whole. The magnet 41 and yoke 42 constitute a magnetic circuit that generates magnetic flux that interlinks with the focusing coil 32 and tracking coil 35.

A protrusion 42a is formed in a portion of the yoke 42 that is not in contact with the magnet 41 so that its tip is located near the tracking coil 35. By providing this protrusion 42a, the magnetic flux interlinking with the tracking coil 35 is increased, and therefore the objective lens driving force in the tracking coil direction: T is increased. Also, yoke 4
2 is provided with a sub-yoke 42b which is provided in a portion not in contact with the magnet 41 and whose tip reaches the vicinity of the focusing coil 32. However, this sub-yoke 42b may be a protrusion integrally molded with the yoke 42, similar to the above-described protrusion 42a. By providing this sub-yoke 42b, the magnetic flux interlinking with the focusing coil 32 increases, so that the focusing direction: F
The driving force of the objective lens is increasing.

As is particularly clear from FIG. 12, each opposing surface of the pair of magnets 41 has a concave portion 4 having an arcuate cross-section perpendicular to the optical axis direction of the objective lens 30.
1a, and the focusing coil 32 is fitted between these two recesses 41a. The dimensions of this recess 41a are such that the movable range of the focusing coil 32 in the direction of the coil center axis of the tracking coil 35 is limited to the size of the pair of magnets 4.
The movable range in the opposite direction is larger than that in the opposite direction. That is, both concave portions 41a are formed on both sides of, for example, an ellipse or a long hole whose long axis coincides with the coil center axis direction of the tracking coil 35.

For example, as shown in FIGS. 12 and 13, a flexible printed circuit board 43 is provided for supplying current to the focusing coil 32 and the tracking coil 35, and the printed circuit board is connected to the leaf spring 36. , 38, and a relay member 37 and base member 3 as fixing parts for each of the leaf springs.
9 is continuously glued. Further, although not particularly shown, the printed circuit board 43 is bonded to each elastic surface of each leaf spring and the fixed portion with a vibration-absorbing adhesive. When the leaf springs 36 and 38 are bent to drive the objective lens 30, resonance of the leaf springs is prevented by the vibration absorbing action caused by the deformation of the printed circuit board 43. By using a material that has vibration absorption properties, the vibration absorption effect is further increased.

Note that, as shown in FIG. 12, a projecting portion 31a protruding from the lens holder 31 that supports the objective lens has cutout portions 31c formed on both sides in the projecting direction of the projecting portion. The coils are drawn out from the focusing coil 32 and the tracking coil 35 to the printed circuit board 43 through the notch. As is clear from the foregoing, the focusing coil 32 and the tracking coil 35 are housed in a magnetic circuit including a pair of magnets 41, but the coils can be pulled out through the cutout 31c. By doing so, the problems associated with each magnet can be narrowed down, making it easier to downsize the magnetic circuit and, by extension, the pickup device as a whole.

A drive for driving the objective lens 30 by the above-described focusing coil 32, tracking coil 35, magnetic circuit including the magnet 41 and yoke 42, the printed circuit board 43, and peripheral small members related thereto. The means are configured. Furthermore, the drive mechanism and the support mechanism including the aforementioned plate springs 36, 38, etc. constitute a drive mechanism that servo drives the objective lens 30. Furthermore,
The drive mechanism and objective lens 30 constitute a movable optical system. The above-described fixed optical system and the movable optical system are coupled with a common optical axis.

Here, the wavelength position 25 will be explained again.

For example, as shown in FIG. 12, a magnetic circuit consisting of a magnet 41, a yoke 42, etc. is fixed to the pickup body 1 by a pair of screws 45, so as is clear from FIG. The plate-shaped base member main body 27 supporting the magnetic circuit is held and fixed by the magnetic circuit and the pick-up body 1. Therefore, a special fixing member for fixing the base body 27 is not required. Further, the wavelength plate 25 is attached to the surface of the base member consisting of the base member main body 27 and the holder 26 on the opposite side to the objective lens 30.

Restore description.

For example, as shown in FIG. 1, a cover member 47 is provided to cover the objective lens 30 and the drive mechanism for servo driving the objective lens. This cover member 47 is supported by the base member 39 and the yoke 42 among the constituent members of the drive mechanism. For details, see Figure 14 a, b, d and e.
As shown in , a flexible engagement claw 47a is formed at one end of the cover member 47.
As shown in FIG. 1, the engaging pawl engages with the lower edge of the end of the yoke 42. As shown in FIG. That is, the edge of the lower surface of the end of the yoke 42 serves as a locking portion for the engaging claw 47a. In addition, the cover member 47
A protrusion 47b is formed at the other end, and the protrusion engages with a recess 39d, which is a locking part, formed on the outer edge of the upper surface of the base member 39. In addition, as is clear from FIGS. 1 and 12, the yoke 4
2 is provided with a tapered portion 42d that engages with and deflects the engaging claw 47a when the cover member 47 is placed over the drive mechanism.
Further, as shown in FIG. 14c, a pair of flexible engagement claws 47c are also formed on both sides of the cover member 47, and the engagement claws are connected to the locking portion 1 formed on the pick-up body 1. ₀ (see Figure 8 a, c, d and f).

As is clear from FIGS. 1 and 14b and 14c, a portion of each portion of the cover member 47 that faces the disk recording surface forms an inclined portion 47d. Further, as is clear from FIG. 1, for example, the cover member 47 is formed along the leaf spring 36, which is a component of the drive mechanism described above, and the inclined portion 47d corresponds to the leaf spring 36. . Since the leaf spring 36 has a cantilever shape, it bends in an inclined manner around the relay member 37, which is a fixed part.
By accommodating the above, the dead space inside the cover member 47 can be minimized.

The cover member 47 is also formed with a plurality of substantially hemispherical protrusions 47e in a portion facing the disk recording surface. By operating a tilt servo mechanism, which will be described later, the entire pickup device is tilted so that the cover member 47 approaches the disk recording surface, but the amount of deformation of the disk recording surface due to so-called warping is extremely large. It is conceivable that the recording surface may come into contact with the portion of the cover member 47 that faces the disk recording surface at the time of abnormal tilt servo operation. Even if such contact occurs, the hemispherical protrusion 47e will come into contact with the recording surface of the disk, and the contact will be smooth and the surface of the disk will not be damaged.

Also on the cover member 47 is a hemispherical projection 47e.
Instead, a pad made of felt or the like may be attached, and this pad also performs the same function as the hemispherical protrusion 47e.

As shown in FIGS. 2 to 6, the pick-up device has a support body 50 made of resin and extending from the side of the pick-up body 1. As shown in FIGS. The support body 50 is connected to the pick-up body 1 by screws or the like. The support body 50 constitutes the main body of the pickup device together with the pickup body 1, and also constitutes a holding mechanism for holding other components such as the plurality of optical elements described above. Note that this holding mechanism is movable along the recording surface of the disk 29.

15a to 15f are diagrams for clarifying the overall shape of the support body 50. FIG. As shown in FIGS. 15a and 15c, the support body 50 has openings 50a and 5 corresponding to the adjustment jig insertion holes 1d, 1f and 1g formed in the pick-up body 1.
0b and 50c are provided. Adjustment jigs are inserted through each of these openings. A longitudinal sensor stay 50d is integrally formed on one end of the support body 50 near the movable optical system (described above) including the objective lens 30. For details, please refer to Sensor Stay 5
0d is connected to the main body of the support body 50 at one end, and is swingable about the one end. However, the sensor stay 50d swings in a plane perpendicular to the disk recording surface. As shown in FIGS. 2, 4, and 5, a screw 51 that rotatably fits into the main body of the support 50 is screwed into the main body of the support 50, and by rotating this screw 51, The swing angle position of the sensor stay 50d is configured to move.

As shown in FIG. 3, the sensor stay 50
A sensor board 52 is fixed on the sensor board 52 with screws 52a (shown in the fourth figure), and a light emitting diode 5 is mounted on the sensor board as shown in FIG.
3 and a pair of photodiodes 54 are fixed. As mentioned above, the pick-up device has
A tilt servo mechanism is provided to ensure that the optical axis of the spot light irradiated onto the disk recording surface always intersects the recording surface at right angles. Although not shown,
For example, a predetermined rotational support shaft is inserted into the round hole 1p of the pick-up body 1 shown in FIG. It forces you. The light emitting diode 53 and photodiode 54 described above act as a sensor for detecting the relative inclination angle between the optical axis of the spot light and the disk recording surface.

On the other hand, a plurality of flexible engagement claws 50e are integrally formed at the other end of the support body 50, that is, the end opposite to the end where the sensor stay 50d is formed. A control circuit board 55 is supported by.

In the pickup device with the above configuration,
The irradiated light emitted from the laser diode 3 sequentially passes through the grating 4, the beam splitter 5, the collimator lens 6, the wavelength plate 25, and the objective lens 30, and is focused on the recording surface of the disk 29 as a fine spot light. Further, the reflected light from the recording surface of the disk 29 travels backward through the objective lens 30, the wavelength plate 25, and the collimator lens 6, enters the beam splitter 5, and then reaches the light receiving element 16 via the multi-lens 20.

As shown in FIG. 16, the light receiving surface of the light receiving element 16 is provided with a photodiode 57 for focus servo for reproduction RF signals and a pair of photodiodes 58 for tracking servo. The light receiving surface of the photodiode 57 is 57a, 5
It is divided into four parts 7b, 57c and 57d. Although it will not be described in detail because it is well known, each divided portion 57a to 57d is formed by utilizing the property that when light having convergence is transmitted through a so-called cylindrical lens, it is converged as two focal lines perpendicular to each other. The amount of light irradiated on the disk is detected and measured, the mutual positional relationship between the disk recording surface and the objective lens 30 is determined, and the objective lens 30 is adjusted accordingly.
is used to perform focus servo. In addition to the function of the cylindrical lens described above, the multi-lens 20 functions as a convex lens that provides convergence to the light reflected from the disk recording surface. Further, a signal for tracking servo is obtained from the difference in the amount of light received by the pair of photodiodes 58, respectively.

As shown in FIG. 17, the objective lens 30 is located at a first position approaching the recording surface of the disk 29 (indicated by a two-dot chain line) and at a second position away from the recording surface (indicated by a one-dot chain line). The stopping position (indicated by a solid line) of the objective lens 30 when the power of the driving means (described above) for driving the objective lens is turned off is between the first position and the second position. It is set closer to the second position than the center of the position. That is, if the movement stroke of the objective lens 30 is S, then the dimension indicated by L in FIG. It is also getting smaller.

Effects of the Invention As detailed above, in the pickup device of the optical information recording/reproducing apparatus according to the present invention, the plate-shaped base member supporting the wavelength plate is connected to the holding member which is a part of the fixed optical system and the movable optical system. It is fixed in a sandwiched manner by a drive mechanism included therein. That is, when the holding member and the drive mechanism are connected to assemble the pickup device, the base member is simply inserted between them and the holding member is fixed.

Therefore, there is no need for a special fixing mechanism for fixing the base member, and the number of parts is reduced.
Furthermore, since the outer base member is also formed into a plate shape, it is easy to make the device smaller, especially in the direction of the optical axis of the irradiated light. Furthermore, as is clear from the above description of the pickup device assembly, there is virtually no need for work to fix the base member, resulting in improved assembly efficiency.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a pick-up device as an embodiment of the invention, and FIGS. 2 to 5 are respectively a view in the direction of the arrows, a view in the direction of the arrows, a view in the direction of the arrows, and a view in the direction of the arrows. 6 is a view in the direction of the − arrow with respect to FIG. 3, FIG. 7 is a partially detailed view of the pick-up device, and FIGS. 8 a to 8 are a front view, a left sectional view, and a right sectional view, each including a half section of the pick-up body. Figure 9 is a partially detailed view of the pick-up device; Figures 10a and 10b are
are respectively a plan view and a front view of a holder carrying a wave plate, and FIG. 10c is a c-o-c with respect to FIG. 10a.
11a, b, and c are respectively a plan view, a right side view, and a rear view of the base member main body holding the holder; FIG. 11d is d-d with respect to FIG. 11a;
12 and 13 are exploded perspective views and perspective views showing the objective lens and its drive mechanism, respectively, and FIGS. 14 a to 14 e are plan views of the cover member, respectively. Left sectional view, right sectional view, front view and rear view, 1st
Figures 5a to 5f show a front view, a left side view, a right side view, a top view, a bottom view, a rear view, and a first view of the support, respectively.
FIG. 6 is a detailed view of the light-receiving surface of the light-receiving element, and FIG. 17 is a diagram for explaining the relationship between the movement stroke and the stop position of the objective lens. Explanation of symbols of main parts, 1...Pickup body, 1a...Through hole, 1a, 1c, 7a...Receiving surface, 1a, 1e, 1f, 1g...Adjustment jig insertion hole, 1h...Adhesive reservoir , 1i...guide hole, 1k
...Spot facing part, 1l...Long hole, 1m, 17a, 5
0a, 50b, 50c...Opening part, 1n, 17
b, 41a... recess, 1p... round hole, 3... laser diode, 4... grating, 4a...
Outer surface, 5... Beam splitter, 5a, 5b...
...Optical axis, 6...Collimator lens, 7, 8, 9,
21...Cylindrical holder, 7b...Inner peripheral surface, 7c...
...pupil, 7d...wall part, 9a...centering guide part, 11, 12, 23b...wavy washer, 1
4...Cylindrical sleeve, 14a...Light passing hole, 1
4b... Wall portion, 14c... Outer surface, 16... Light receiving element, 17... Plate base member, 18... Pressing spring, 19a, 19b, 23, 39a, 39b, 4
5, 51, 52a...Screw, 20...Multi lens, 21a...Annular groove, 23a...Washer, 2
3c... Neck sleeve, 25... Wave plate, 26...
...Holder, 26a... Spot facing portion, 26b... Arc-shaped portion, 26d, 47b... Protrusion, 26e... Outer periphery, 26f... Arm portion, 26g... Bent portion, 2
7...Base member main body, 27a...Support protrusion, 2
7b...center hole, 29...disk, 30...objective lens, 30a...lens pad, 30b...
Counterweight, 31...Rin's holder, 31
a, 31b...projection, 31c...notch, 32
... Focusing coil, 34 ... Bobbin, 3
5... Tracking coil, 36, 38... Leaf spring, 37... Relay member, 37a... Projection, 37
b... Adhesive relief groove, 39... Base member, 3
9c...Positioning protrusion, 39d...Recess, 41...
...Magnet, 42...Yoke, 42a...Protrusion, 42b...Sub yoke, 42d...Tapered part, 43...Printed circuit board, 47...Cover member, 47a, 50e...Flexible engagement claw, 47d …
...Slanted portion, 47e...Semispherical projection, 50...Resin support, 50d...Sensor stay, 52...Sensor board, 53...Light emitting diode, 54,5
7, 58...Photodiode, 55...Control circuit board.

Claims (1)

[Scope of Claims] 1. A fixed optical system including a plurality of optical elements including a wavelength plate, a plate-shaped base member supporting the wavelength plate, a holding member holding each of the optical elements and the base member, and a recording device. a movable optical system that includes an objective lens for irradiating a recording surface of a medium with a spot light and a drive mechanism that servo drives the objective lens, and is connected to the fixed optical system by a common optical axis; 1. A pickup device for an optical information recording/reproducing device, characterized in that the member is held between the holding member and the drive mechanism. 2. A patent characterized in that the wavelength plate is attached to the main body of the base member via a holder that is slidable and rotatable in a plane perpendicular to the optical axis with respect to the main body of the base member. A pickup device in an optical information recording/reproducing apparatus according to claim 1.