JPH0991710A - Optical disk device and objective lens actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve the problem incapable of converging light flux on a signal surface of an optical disk because of this signal surface which recedes from a focal length of an objective lens mounted on a lens holder when mold cover is adopted as a deck cover. SOLUTION: In the optical disk where a base 20 is mounted with an optical pickup 30 for recording and reproducing the signal of an optical disk D and driving system parts of the optical disk D, and these driving system parts are covered around with the deck cover 64, this deck cover 64 is formed by molding the mold cover having a leg part with a snap fit. Then, the objective lens 34 constituting the optical pickup 30 is projecting out to the side of the optical disk D, thereby dissolving the problem.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for recording / reproducing information signals of an optical disk and an objective lens actuator used for the same.

[0002]

2. Description of the Related Art Conventionally, an optical pickup provided in this type of optical disk device is constructed as shown in FIG. 7, for example. In FIG. 7, a light beam L emitted from a light emitting element 4 such as a semiconductor laser passes through a diffraction grating 5 and a semi-transmissive reflective film 7, and is focused by an objective lens 2 on a signal surface of an optical disk D which is also called an optical disk.

The return light reflected by the signal surface of the optical disc D is again focused from the objective lens 2 through the semi-transmissive reflection film 7 to the photodetector 6, and the signal of the optical disc D is detected by the photodetector 6. It is supposed to be done. This optical disc D rotates in the rotation direction R, and the optical pickup moves in the direction of arrow T.
By moving in the tracking direction of R, the optical pickup creates a signal train of the optical disc D.

As shown in FIG. 8, the objective lens 2 is
Lens holder 8 that constitutes the objective lens actuator 3
It is attached to the recessed portion 9 formed by gluing or the like. On the bottom surface of the concave portion 9, a hole 10 through which the light flux emitted from the light emitting element 4 or the return light from the recording surface of the optical disc D passes is formed.

A coil bobbin 11 is attached to the opening formed in the lens holder 8. That is, the objective lens actuator 3 includes a lens holder 8 including the objective lens 2 and the coil bobbin 11, and an elastic support body (not shown) having one end fixed to the lens holder 8 and the other end fixed to a fixing portion. ing. The objective lens actuator 3 includes a uniaxial actuator that moves the objective lens 2 in the focusing direction, and a biaxial actuator that moves the objective lens supported by an elastic support in two directions of the focusing direction and the tracking direction. There is.

Further, as shown in FIG. 9, the periphery of the objective lens actuator 3 is covered with a cover 12 having an opening 12a for exposing the objective lens 2, and the objective lens 2, the diffraction grating 5 and the semi-transmissive reflection film. Foreign matter is prevented from entering the optical components such as 7 or the external light is prevented from affecting the optical components.

Further, the optical pickup is mounted on a base plate 13 made of sheet metal. Since a drive system component (not shown) of the optical disk D is also provided on this base plate 13, foreign matter enters the drive system component. In order to prevent this, the upper part thereof is covered with a deck cover 14 having an opening 14a for exposing the objective lens 2. As shown in FIG. 10, the deck cover 14 is formed by press-molding a sheet metal and coating it. A screw 16 is screwed into a resin-made mounting boss 15 formed on the base plate 13. It is installed.

[0008]

However, in the conventional optical disc apparatus, the optical pickup mounted on the base plate 13 and the drive system components of the optical disc D are covered by the deck cover 14 made of sheet metal, so that the base plate made of sheet metal is used. The resin-made mounting boss 15 must be outsert-molded on the resin 13, and the manufacturing cost is increased.
Since the screws 16 are screwed into the mounting bosses 15 to mount the deck cover 14, the number of assembling steps is increased.

As a remedy for this, it is conceivable to mold the deck cover so as to have legs with snap fits. If such a mold cover is adopted, it is only necessary to open fit holes in the base plate. ,
The manufacturing cost can be reduced. Further, since the mold cover can be attached by a touch operation that simply fits a snap fit into the fit hole, the number of assembling steps can be reduced.

However, while the wall thickness t of the deck cover 14 made of sheet metal is about 0.3 mm, the wall thickness of the mold cover must be molded to about 1.0 mm in order to have strength. . Therefore, the optical disc D and the objective lens 2
If a thick mold cover is provided between the optical disc D and the optical disc D, the signal surface of the optical disc D becomes farther than the focal length S of the objective lens 2 mounted on the lens holder 8, and the light flux L cannot be focused on the signal surface. There was a problem. In this case, the assembly clearance may be absorbed by adjusting the assembly height of the base plate 13 or the like, but it is absorbed by the assembly clearance in view of the assembling space due to compactness. It was impossible to do.

In view of the above points, the present invention adopts the mold cover as the deck cover to reduce the manufacturing cost and the number of assembling steps, and even when the mold cover is adopted, the light flux transmitted through the objective lens is transmitted to the signal of the optical disc. An object of the present invention is to provide an optical disk device and an objective lens actuator that can be focused on a surface.

[0012]

According to the present invention, the above object is to mount an optical pickup for recording / reproducing signals of an optical disc and a drive system component of the optical disc on a base, and surround the periphery of the drive system component with a deck cover. In the optical disc device, the deck cover is molded by the mold cover having the legs with snap fit, and the objective lens forming the optical pickup is projected toward the optical disc side.

An objective lens actuator including a lens holder including an objective lens and a coil bobbin, and an elastic support member having one end fixed to the lens holder and the other end fixed to a fixing portion is used as an optical disk drive system component. This is achieved by an objective lens actuator in which the objective lens is mounted on the lens holder so as to project toward the optical disc, when a mold cover having legs with snap fit is adopted as the deck cover for covering the.

The optical disk device and actuator according to the present invention are applied when a mold cover having legs with snap fit is adopted as a deck cover for covering drive system parts of the optical disk. Since such a mold cover is used only by opening the fitting hole in the base plate, the manufacturing cost is reduced as compared with the conventional structure in which the resin mounting boss is outsert-molded on the base plate. Because you can. Also, since the mold cover can be attached by a touch operation just by inserting a snap fit into the fit hole, the number of assembling steps can be reduced as compared with the conventional structure in which a screw is screwed into each mounting boss. Because you can.

However, since the mold cover is thicker than the conventional sheet metal cover in order to have strength, if the mold cover is provided between the optical disc and the objective lens, the optical disc is longer than the focal length of the objective lens. The signal surface of is moved away, and the light flux is not focused on the signal surface.

Therefore, in the optical disk device and the actuator according to the present invention, by mounting the objective lens on the lens holder so that the objective lens projects toward the optical disk, the increase in the thickness of the mold cover is absorbed by the projection of the objective lens. Then, the light flux passing through this objective lens is focused on the signal surface of the optical disc.

The protrusion of the objective lens toward the optical disc side can be easily secured by locally increasing at least the height of the lens mounting portion of the lens holder.

[0018]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiments described below are preferred examples of the present invention, and therefore, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 5 shows an embodiment of the optical disk device according to the present invention. In FIG. 5, the optical disk device is used for reproducing information or signals recorded on the optical disk D, or for recording and reproducing signals or information on the optical disk D, for example.

The optical disc D can be detachably set in the mounting portion 31 of the spindle motor 29.
The spindle motor 29 is fixed to the base plate 20. The optical pickup 3 is mounted on the base plate 20.
0 and the drive system 33 are set. This drive system 33
Includes a feed motor 22 and gears 24, 26, 28 and the like.

By driving the feed motor 22, the output of the feed motor 22 is transmitted to the rack 52 of the optical pickup 30 via the gears 24, 26 and 28. As a result, the optical pickup 30
Drives the feed motor 22 to guide the guide bar 5
Tracking is possible along arrow 4 in the direction of arrow TR.

Next, referring to FIG. In FIG.
This optical pickup 30 is shown more specifically in an enlarged manner. As described above, the optical pickup 30 can perform the tracking operation along the guide bar 54 in the tracking direction TR.

The optical pickup 30 has a main body 50 and a cover 32. The main body 50 has the guide bar 5
4 is provided, and a rack 52 is formed. In addition, the main body 50 has an optical system 6
4 are provided.

The optical system 64 includes the following optical elements. The light flux L emitted from the light emitting element 38 such as a semiconductor laser is reflected by the semi-transmissive reflection film 44 through the diffraction grating 40, passes through the objective lens 34, and is focused on the signal surface of the optical disc D shown in FIG. It has become so.

The return light flux L reflected on the signal surface of the optical disc D is transmitted from the objective lens 34 to the semi-transmissive reflection film 44.
Then, the light is focused on the photodetector 42. As a result, the signal on the signal surface of the optical disc D in FIG. 5 can be reproduced, for example.

A part of the light emitting element 38 which is each optical component of the optical system 64, the diffraction grating 40, the photodetector 42,
The semi-transmissive reflective film 44 is housed in the housing portion 68 of the main body 50.

The focus position of the light beam L emitted from the light emitting element 38 on the optical disc D and the spot position on the recording surface of the optical disc D are adjusted in the optical axis direction of the objective lens 34 and in the direction orthogonal to the optical axis. The position is adjusted by finely adjusting the objective lens 34.
The objective lens actuator 60 according to the present invention, which is schematically illustrated in FIG. 1, is used to adjust the position of the objective lens 34.

The objective lens actuator 60 is of an electromagnetic drive type and includes a lens holder 61 to which the objective lens 34 is attached, a plurality of elastic supports (not shown), and a drive section for generating a drive force. There is. The lens holder 61 is
A plurality of elastic supports are provided for the fixed portion so that the position of the objective lens 34 in the optical axis direction, that is, the focus position and the position in the direction orthogonal to the optical axis of the objective lens 34, that is, the tracking position are adjustable. There is. The objective lens actuator 60 includes a biaxial actuator that moves the objective lens 34 supported by the elastic support member in two directions of the focusing direction and the tracking direction, and a uniaxial actuator that moves the objective lens 34 in the focusing direction. Both forms can be employed in the present invention.

The lens holder 61 includes a coil bobbin 62.
Is formed, and a lens mounting portion 61a for fixing the objective lens 34 is formed.
FIG. 3 shows a first objective lens actuator according to the present invention.
It is a schematic diagram showing an embodiment. In FIG. 3, a hole 63 through which the light flux L emitted from the light emitting element 38 or the return light from the recording surface of the optical disc D passes is formed on the bottom surface of the lens mounting portion 61a. This lens mounting part 61
A concave portion (indicated by 9 in FIG. 8) for mounting an objective lens as in the prior art is not formed in a, and the objective lens 34 is attached to the lens mounting portion 61a of the lens holder 61 by adhesion or the like. It is attached. Therefore, the objective lens 34
Is an optical disc D that does not have a concave portion unlike the conventional one.
It is attached to the lens holder 61 by projecting to the side. Further, in the present embodiment, if the overall thickness of the lens holder 61 is increased, the objective lens 34 will protrude toward the optical disc D side by that amount. Will be.

FIG. 4 is a schematic view showing a second embodiment of the objective lens actuator according to the present invention.
In FIG. 4, in the second embodiment, the lens mounting portion 61a of the lens holder 61 is formed by locally increasing the height of the lens mounting portion 61a as compared with the other upper surface portion, and locally protrudes toward the optical disc D side. 61a to the objective lens 34 by adhesion or the like
Is attached. On the bottom surface of the lens mounting portion 61a, the hole 63 through which the light flux L emitted from the light emitting element 38 or the return light from the recording surface of the optical disc D passes is formed as described above. In the second embodiment, not only the conventional concave portion (indicated by 9 in FIG. 8) is not formed, but also the lens mounting portion 61a in which the height is locally increased on the optical disc D side. Since the objective lens 34 is attached on the upper side, the corresponding portion is projected toward the optical disc D side.

Although not shown, the coil bobbin 62 has an opening for inserting the magnetic circuit of the base, and in the case of a biaxial actuator,
A focus coil and a plurality of tracking coils are attached. In this case, the focus coil is wound around the bobbin 62 along an axis parallel to the optical axis of the objective lens 34. The tracking coil is formed by winding the coil in an elliptical or rectangular shape, and is attached to one side surface of the focus coil.

The elastic support body is a suspension formed of an elastic body such as a leaf spring, and is attached between the lens holder 61 and the fixed portion by a method such as adhesion or soldering so as to be parallel to each other. A pair of yoke portions and the like (not shown) forming a magnetic circuit are formed on the base, and a magnet is attached to the yoke to form a magnetic circuit.

In the objective lens actuator 60 thus constructed, the focus servo signal and the current based on the tracking servo signal are supplied to the focus coil and the tracking coil, respectively. As a result, the lens holder 61, that is, the objective lens 34 is driven in the focus direction and the tracking direction by the DC magnetic field of the magnetic circuit and the magnetic fields generated from the focus coil and the tracking coil.

Further, as shown in FIGS. 1 and 6, the periphery of the objective lens actuator 60 is covered with a cover 32 having an opening 32a exposing the objective lens 34, and the objective lens 34, the diffraction grating 40, and the half. Prevent foreign matter from entering the optical components such as the transflective film 44,
Alternatively, it prevents external light from affecting the optical components.

Further, the optical pickup 30 is mounted on a base plate 20 made of sheet metal.
Spindle motor 29, feed motor 22 and gear 2
Since drive system components such as 4, 26 and 28 are also provided, in order to prevent foreign matter from entering the drive system components, the upper part thereof is covered with a deck cover 64 having an opening 64a exposing the objective lens 34. It is being appreciated.

As shown in FIG. 2, this deck cover 64
Is formed into a substantially rectangular shape by resin molding, and leg portions 64b are integrally formed at appropriate positions on the peripheral edge portion. A wedge-shaped snap fit 64c is formed at the lower end of each leg 64b. The opening 64a is formed as a long hole along the direction to always expose the objective lens 34 in order to move the objective lens 34 in the tracking direction.

On the other hand, the base plate 20 on which the mold cover 64 is mounted is formed by pressing a sheet metal into a substantially rectangular shape, and an opening 20a for supporting the optical pickup 30 is formed in the center thereof. Are formed. In addition, at four corners of the base plate 20, notches 20b for fixing the base plate 20 to a casing (not shown) with screws.
Are formed. Further, fit holes 20c for fitting snap fits 64c formed at the lower ends thereof are opened at respective positions corresponding to the leg portions 64b of the mold cover 64 in the peripheral portion of the base plate 20.

As described above, if the mold cover is adopted as the deck cover 64, it is only necessary to open the fitting hole 20c in the base plate 20, and the conventional structure for outsert-molding the resin mounting boss on the base plate. The manufacturing cost can be reduced as compared with (see FIG. 10). Further, the mold cover 64 is mounted by fitting the leg portion 6 of the mold cover 64 into the fitting hole 20c opened in the base plate 20.
Since it can be performed by a touch operation just by inserting the snap fit 64c formed on the 4b, compared with the conventional structure in which a screw is screwed to each mounting boss (see FIG. 10),
The number of assembly steps can also be reduced.

As described above, this mold cover 64
Has a larger wall thickness T than the conventional sheet metal cover. For example, the wall thickness t of the conventional sheet metal cover is about 0.3 mm (see FIG. 9), while the wall thickness T of the mold cover 64 is
In terms of strength, it should be molded to about 1.0 mm. Therefore, when the mold cover 64 is provided between the optical disc D and the objective lens 34, the signal surface of the optical disc D becomes farther than the focal length S of the objective lens 34, and the light flux is not focused on the signal surface.

However, as shown in FIGS. 3 and 4, the optical disk device and the objective lens actuator according to the present invention are mounted on the lens holder 61 so that the objective lens 34 projects toward the optical disk D side. Therefore, by absorbing the increase (T−t) in the thickness of the mold cover 64 by the protrusion H of the objective lens 34, the light flux L passing through the objective lens 34 is reliably focused on the signal surface of the optical disc D. be able to. Therefore, the protrusion H of the objective lens 34 is set to 0.7 mm, for example.

In this case, as shown in FIG. 4, the protrusion H of the objective lens 34 toward the optical disc D side can be obtained by locally increasing at least the height of the lens mounting portion 61a of the lens holder 61, as shown in FIG. It can be easily secured.

In the above embodiment, an optical pickup for a mini disk is used as an example for explanation.
Not limited to this, it is obvious that an optical pickup for other optical disks or the like can be applied to the present invention.

[0043]

As described above, according to the optical disk device and the objective lens actuator of the present invention, the mold cover is adopted as the deck cover to reduce the manufacturing cost and the number of assembling steps, and the mold cover is adopted. It is also possible to provide an optical disk device and an objective lens actuator that can focus the light flux that has passed through the objective lens on the signal surface of the optical disk.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main part of an optical disc device according to the present invention.

FIG. 2 is a perspective view showing a base plate and a deck cover adopted in the optical disk device according to the present invention.

FIG. 3 is a first objective lens actuator according to the present invention.
It is a schematic diagram showing an embodiment.

FIG. 4 is a second objective lens actuator according to the present invention.
It is a schematic diagram showing an embodiment.

FIG. 5 is a perspective view showing an embodiment of an optical disc device according to the present invention.

6 is an enlarged perspective view showing the optical pickup of FIG.

FIG. 7 is a perspective view showing an example of a conventional optical pickup.

FIG. 8 is a schematic view showing a main part of a conventional objective lens actuator.

FIG. 9 is a schematic diagram showing a main part of a conventional optical disc device.

FIG. 10 is a perspective view showing a base plate and a deck cover used in a conventional optical disc device.

[Explanation of symbols]

 20 Base Plate 20a Opening 20b Notch 20c Fit Hole 30 Optical Pickup 32 Cover 34 Objective Lens 60 An objective lens actuator is used. 61 lens holder 61a lens mounting part 62 coil bobbin 63 hole through which light passes 64 deck cover 64a opening 64b leg 64c snap fit D optical disc D

Claims (4)

[Claims] 1. An optical pickup for recording / reproducing signals of an optical disc, and an optical disc device in which a drive system component of the optical disc is mounted on a base, and the periphery of the drive system component is covered with a deck cover. An optical disk device characterized in that the objective lens forming the optical pickup is projected to the optical disk side while being molded by a mold cover having the above. 2. The optical disk apparatus according to claim 1, wherein the objective lens is projected toward the optical disk by locally increasing the height of the lens mounting portion of the lens holder. 3. An objective lens actuator comprising: a lens holder including an objective lens and a coil bobbin; and an elastic support member having one end fixed to the lens holder and the other end fixed to a fixing portion, which is a drive system component of an optical disk. When a mold cover having a plurality of snap-fitted legs is used as a deck cover for covering the objective lens actuator, the objective lens actuator is mounted on the lens holder so as to project toward the optical disc. 4. The objective lens actuator according to claim 3, wherein the objective lens projects toward the optical disc by locally increasing the height of the lens mounting portion of the lens holder.