JPH09326128A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance rigidity of a lens holder without increasing a thickness size of a device and to heighten its high order resonance frequency in an axial slide type optical pickup device. SOLUTION: In the optical pickup device 1 provided with the lens holder 5, a circular lens hold part 107 projecting from the upper surface 55 of the lens holder 5 and an objective lens 7 held by the lens hold part 107, the lens holder 5 is provided with a projecting surface 56 entirely projecting the periphery of the circular lens hold part 107 until the upper surface of the lens hold part 107, and then, the device is constituted so that a thickness part 57 of the periphery of a luminous flux passing opening hole 52 is increased. The thickness part 57 is formed on the lens holder 5 by using a gap caused on the periphery of the circular lens hold part 107. Then, the rigidity of the device is enhanced without increasing the thickness of the device. Thus, the high order resonance frequency of the lens holder is heightened, and an excellent servo control characteristics is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for reproducing or reproducing and writing an optical disk, a magneto-optical disk or the like, and more particularly to improving the rigidity of a lens holder holding an objective lens. Is.

[0002]

2. Description of the Related Art As an optical pickup device, there is known an optical pickup device provided with a shaft sliding type objective lens driving mechanism. As shown in FIG. 4, this type of optical pickup device 100
Is a lens holder 102 that holds the objective lens 101.
Are supported so as to be movable with respect to the support shaft 103 in the axial direction (focusing direction) and the direction around the axial line (tracking direction). Then, the lens holder driving mechanism including a magnetic driving circuit including the driving coil 104 and the magnet 105 is used to drive the lens holder 102 in the axial direction and around the axial direction to adjust the focusing of the objective lens 101 held therein. And tracking adjustment.

The lens holder 102 supported by the support shaft 103 is a cup-shaped device case 1 having an upper opening.
It is stored in 10. The upper opening of the device case 110 is covered with a device cover 120.

In the lens holder 102, a light flux passage opening 106 is formed in a portion on one side of the support shaft 103. A reflection mirror 111 including a prism for directing laser light to the objective lens 101 is disposed below the hole 106. An upper end portion of the opening 106 serves as a lens holding portion 107 that annularly projects from the upper surface of the lens holder 102. This lens holder 10
The objective lens 101 is attached to the lens 7. Since the lens holding portion 107 thus projects upward, the device cover 120 includes the objective lens 101 and its annular holding portion 107 so that this portion does not interfere with the device cover 120. An opening 121 having a size is formed.

Here, during reproduction of the optical disk, the lens holder holding the objective lens is constantly moved minutely by the magnetic drive circuit. Therefore, if the lens holder resonates during driving, it becomes impossible to properly perform servo control for its positioning.
Therefore, it is desirable to set the high-order resonance frequency of the lens holder to a high value so that resonance does not occur in the lens holder in a practical frequency range.

In order to increase the higher resonance frequency of the lens holder, it is necessary to increase the mechanical rigidity of the lens holder. An effective means for this is to make the lens holder thick.

[0007]

When the lens holder 102 is simply thickened, the device thickness (FIG.
The dimension H) indicated by is also large. This violates the demand for thinner optical pickup devices, and is not a practical solution.

Further, as shown in FIG. 4, the portion of the lens holder 102 on the side where the light flux passage opening 106 is formed is in a state of a large cross section loss due to the opening 106. In order to increase the rigidity of this portion, the opening 1
It is conceivable that the wall portion 109 around 06 is extended downward to a position covering the periphery of the reflection mirror 111. However, depending on the shape of the lens holder, such a hanging wall portion may not be formed in some cases.

[0009] The object of the present invention is to solve the above problems.
An object of the present invention is to propose an optical pickup device capable of increasing the rigidity of a lens holder without inhibiting the thinning of the device.

[0010]

In order to solve the above problems, the present invention provides a lens holder, an annular lens holding portion projecting from the upper surface of the lens holder, and a lens holding portion. In an optical pickup device having an objective lens, the lens holder includes a thick portion formed by projecting at least a part of a circumference of the annular lens holding portion to an upper surface of the lens holding portion. Has become.

In the optical pickup device of the present invention, the thick portion is formed in the lens holder by utilizing the gap formed by removing the covering of the peripheral portion of the annular lens holding portion which is conventionally covered by the device cover. ing. Therefore, the rigidity of the lens holder can be increased without increasing the thickness of the device. As a result, the high-order resonance frequency of the lens holder can be increased, and an optical pickup having good servo control characteristics can be manufactured.

It is desirable that such a thick portion be formed in a state of surrounding the annular lens holding portion.

Here, since the upper surface of the lens holder is projected in this way, the shape and size of the opening formed in the device cover covering the upper surface of the lens holder are the same in the tracking direction of the lens holder and in the tracking direction. It is desirable to set so as to include the movement loci of the lens holder and the thick portion in accordance with the movement in the focusing direction.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A shaft sliding type optical pickup device to which the present invention is applied will be described below with reference to the drawings.

FIG. 1A shows the appearance of the optical pickup device. The optical pickup device 1 has a cup-shaped device case 2 having an upper opening, and a device cover 3 covering the upper opening. On the side surface of the device case 2, an introduction hole 2 for the laser light supplied from the side of an optical device (not shown) in which the optical pickup device 1 is incorporated.
a is formed. Further, the device cover 3 has a structure shown in FIG.
As shown in (B), an opening 3a is formed which also serves as a path for the laser light emitted from the optical pickup device 1 toward the optical disc.

FIG. 2A shows a lens holder incorporated in the optical pickup device 1. Further, FIG. 2B shows a device cross-sectional structure of a portion cut along line 2B-2B in FIG.

Explaining with reference to these figures, the optical pickup device 1 has a structure similar to that of the conventional shaft sliding type shown in FIG. 4 as a whole. That is, the lens holder 5 supported by the support shaft 4 provided upright from the bottom wall of the device case 2 is provided. The lens holder 5 is
The support shaft 4 is supported so as to be movable in the axial direction (focusing direction) and the direction around the axis (tracking direction).

A pair of focusing drive coils 6a and 6b are attached to the outer peripheral surface of the lens holder 5. A focusing magnet (not shown) is attached to the inner peripheral side surface of the device case 2 facing the drive coils 6a and 6b. A magnetic drive mechanism including the drive coil and the magnet constitutes a drive mechanism for driving the objective lens 7 held by the lens holder 5 in the focusing direction. Similarly, a pair of tracking drive coils 8a and 8b mounted on the outer peripheral surface of the lens holder 5, and tracking magnets 9a and 9b mounted on the inner peripheral side surfaces of the device case 2 facing each other.
A drive mechanism for driving the objective lens 7 held by the lens holder 5 in the tracking direction is constituted by the magnetic drive mechanism including the.

As can be seen from FIG. 2A, the lens holder 5 has a flat thickness as a whole and a substantially octagonal outline shape. At the center of this lens holder 5, the support shaft 4
Is formed with a shaft hole 51. This shaft hole 5
In the portion of the lens holder 5 on one side of No. 1, a light flux passage opening 52 is formed which penetrates vertically and extends.
Below the opening 52, the reflection mirror 11 mounted on the bottom surface of the device case 2 is located.

A lens holding portion 53 including a stepped inner peripheral surface 53a into which the outer peripheral portion 7a of the objective lens 7 is just fitted is formed at the upper end portion of the light flux passage opening 52, and the objective lens is provided here. 7 is attached and fixed.

Here, on the upper surface 55 of the lens holder 5, a peripheral portion of the lens holding portion 53 projects upward to form a protruding surface 56. In FIG. 2A, in order to show the range of the projecting surface 56, the part of the projecting surface 56 is shown by using diagonal lines. By forming the protruding surface 56 in this manner, the 2B-2B cross section shown in FIG.
In FIG. 2B, the lens holder 5 at this portion forms a thick portion 57.

In other words, the lens holder 5, like the conventional lens holder shown in FIG.
Not only the annular projection 107 as the lens holding portion is projected, but also the surrounding portion is also projected as a whole to form the protruding surface 56. In FIG. 2B, the portion of the annular protrusion 107 is shown by a broken line.
In this way, by forming the protruding surface 56 around the portion of the lens holder 5 where the light flux passage opening 52 is formed, this portion becomes the thick portion 57 as a whole. FIG.
Other than the cross section shown in (B), the lower portion of the protruding surface 56 is also a thick portion 57.

In the lens holder 5 of the present embodiment, the projecting surface 56 on the upper surface thereof is projected to a height that exactly matches the upper surface 3b of the apparatus cover 3. And this protruding surface 5
The surface of the objective lens 7 held by the lens holding portion 53 formed in 6 is in a state of protruding slightly upward from the protruding surface 56.

In this way, since the objective lens 7 held by the lens holder 5 and the protruding surface 56 around it are projected upward (that is, on the side where the optical disc is arranged),
An opening 3a having a size including these is formed in the device cover 3. To be precise, since the lens holder 5 moves in the focusing direction and the tracking direction,
The aperture 3a is set so as to have a size and a shape that include the movement trajectories of the objective lens 7 and the protruding surface 56 during the focusing operation and the tracking operation.

In the optical pickup device 1 of this example,
By forming the upper surface of the lens holder 5 on the side of the lens holding portion 53 as the protruding surface 56, this portion of the lens holder is formed as the thick portion 57. That is, as shown in FIG. 4, a light flux passage opening in the lens holder 5 is utilized by utilizing a peripheral portion (a portion indicated by an arrow A) of the annular lens holding portion 107, which has conventionally remained as a dead space. The cross-sectional rigidity of the side where 52 is formed is increased. As a result, the higher resonance frequency of the lens holder 5 can be increased, and the possibility of an unstable control state during the servo operation can be reduced.

Further, since the wall thickness of the lens holder is increased by utilizing the portion which has been left as a dead space in the prior art, the thickness of the device is not increased.

(Other Embodiments) FIG. 3 shows a main part of a modified example of the optical pickup device 1 described above. In the optical pickup device 1A shown in this figure, the projecting surface 56 formed on the lens holder 5 is projected more than the device cover 3. The lens holding portion is formed so that the objective lens 7 can be housed so that the distance between the objective lens and the disk is the same as in the first embodiment. Therefore, when the objective lens 7 is mounted on the inner peripheral surface 53a, the upper surface of the objective lens 7 is located completely below the protruding surface 56.

In this case, the amount of protrusion of the protrusion surface 56 can be set within a range in which this portion does not interfere with the optical disc D facing it.

The optical pickup device 1 thus constructed
Also in A, it is possible to obtain the same effects as those of the optical pickup device 1 shown in FIGS. Especially, in the case of this example, the thick portion can be made thicker,
The rigidity of the lens holder 5 can be further increased.

[0030]

As described above, in the optical pickup device of the present invention, the peripheral portion of the lens holder on the side of the annularly projecting lens holding portion is also projected upward, whereby the light flux passing through the lens holder is passed. The configuration is such that the thick portion around the portion where the use opening is formed is increased. Therefore, according to the present invention, it is possible to make the lens holder thicker by utilizing the peripheral portion of the annular projection that is conventionally formed as the lens holding portion. Therefore, the rigidity of the lens holder and the higher resonance frequency thereof can be increased without increasing the thickness of the device. As a result, according to the present invention, an optical pickup device having stable servo control characteristics can be realized.

[Brief description of drawings]

FIG. 1A is an external perspective view of an optical pickup device to which the present invention is applied, and FIG. 1B is a perspective view showing a device cover thereof.

2A is an external perspective view of a lens holder incorporated in the apparatus of FIG. 1, and FIG. 2B is a schematic cross-sectional view showing a portion cut along line 2B-2B of FIG.

FIG. 3 is a schematic partial cross-sectional view showing a modified example of the apparatus of FIG.

FIG. 4 is a schematic sectional view of a conventional optical pickup device.

[Explanation of symbols]

 1 Optical Pickup Device 2 Device Case 3 Device Cover 3a Opening Hole 4 Support Shaft 5 Lens Holder 52 Light Beam Passing Opening Hole 53 Lens Holding Section 53a Stepped Inner Surface for Lens Holding 55 Top Surface of Lens Holder 56 Top Surface of Lens Holder Protruded surface formed 57 Thick part of lens holder 7 Objective lens 11 Reflection mirror 107 Lens holding part consisting of annular protrusion

Claims (3)

[Claims] 1. An optical pickup device having a lens holder, an annular lens holding portion protruding from an upper surface of the lens holder, and an objective lens held by the lens holding portion. An optical pickup device comprising a thick portion formed by projecting at least a part of a peripheral lens holder upper surface portion to an upper surface of the lens holding portion. 2. The optical pickup device according to claim 1, wherein the thick portion is formed so as to surround the circumference of the annular lens holding portion. 3. The device cover according to claim 1, further comprising a device cover that covers an upper surface of the lens holder, and the device cover has an opening in a portion facing the upper surfaces of the lens holder and the thick portion. The light is characterized in that the opening is set in a shape and a size including a movement locus of the lens holder and the thick portion in accordance with the movement of the lens holder in the tracking direction and the focusing direction. Pickup device.