An optical pick-up actuator includes a lens holder, a magnetic circuit, a wire spring, a wire holder, and a damper material receptacle. The lens holder includes an objective lens. The magnetic circuit moves the lens holder. The wire spring is coupled at one end thereof to a side of the lens holder, and supports the lens holder. The wire holder fixes the other end of the wire spring. The damper material receptacle defines an insert hole and a through-hole, through which the other end of the wire spring is inserted and passes. The damper material receptacle holds a predetermined damper material that absorbs vibrations imparted on the wire spring. The damper material defines an injecting hole, through which the damper material is injected, separately from the insert hole and the through-hole.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical pick-up actuator.

2. Description of the Related Art

In general, an optical pick-up actuator is an apparatus that uniformly maintains the position of an objective lens with respect to an optical recording medium, such as a CD or DVD, by driving a lens holder containing the objective lens in focusing, tracking, and tilting directions, in order to follow the tracks in the optical writing medium.

FIG. 1is a perspective view of an optical pick-up actuator according to the related art.

Referring toFIG. 1, an optical pick-up actuator according to the related art includes a lens holder2having an objective lens1installed therein. A focusing coil3and a tracking coil4are respectively wrapped around the lens holder2.

Four wire springs5are fixed on the lens holder2. The wire springs5electrically connect the focusing and tracking coils3and4.

The lens holder2is supported by magnets6provided on a base7of the actuator. The magnets6are fixedly installed on a yoke8to face the focusing and tracking coils3and4. The yoke8may be integrally formed with the base7, or separately attached to the base7.

A wire holder9for fixing the opposite ends of the wire springs5is formed at one side of the base. A circuit board10is installed on the rear surface of the wire holder9.

FIG. 2is a perspective view showing wire springs coupled to a lens holder in an optical pick-up actuator according to the related art.

Referring toFIG. 2, a fixing protrusion11is formed on either side at the top and bottom of the lens holder2. The fixing protrusion11has a through-hole12through which the wire spring5passes.

A connecting protrusion13is formed facing each of the fixing protrusions11on either side surface of the lens holder2. A stepped receiving portion11ais formed on the outer surface of the fixing protrusion11. The wire springs5electrically connect the focusing coil3to the tracking coil4at the connecting protrusion13.

In order to couple the wire springs5to the lens holder2, the wire springs5pass through the through-holes12, and an adhesive epoxy is applied to the receiving portion11ato adhere the wire springs5to the lens holder2.

However, the receiving portion11ais only stepped, and there is no structure provided to prevent the applied epoxy from flowing to the adjacent structures. Thus, during the process of applying adhesive, the adhesive may drip from the receiving portion11aand the fixing protrusion11, causing a loose attachment between the wire spring5and the lens holder2.

Also, in the process of applying adhesive to the outer surface of the fixing protrusion11, if the adhesive should drip elsewhere, more adhesive needs to be used in lieu of the dripped adhesive, thereby wasting adhesive.

Additionally, when an excessive amount of adhesive is applied, the weight of the lens holder2increases, thereby deteriorating the driving characteristics (such as focusing and tracking) of the lens holder, which focuses light onto a disk.

Referring toFIG. 3, the wire holder9is either coupled to the base7or integrally formed with the base7. There are four filling holes14formed in the wire holder9. The filling holes14extend a predetermined depth into the wire holder9from its front surface. The filling holes14may alternately be opened at the front and the sides.

Through-holes15having almost the same diameter as the wire springs5are formed through the wire holder9, so that the opposite ends of the wires5are inserted through the filling holes14and the through-holes15, reaching the rear surface of the wire holder9.

A damper material16made of an ultraviolet ray hardenable viscoelastic material that has undergone gelation is filled to enclose the wire spring5inside the filling hole14. Here, the liquid damper material16that is injected into the filling hole14is formed using ultraviolet ray exposure for quick hardening, resulting in a viscoelastic material.

Also, the other ends of the wire springs5are soldered to a land of the circuit board10at the rear surface of the wire holder9, to induce the flow of current through the focusing and tracking coils3and4.

During operation, the magnets6emit magnetic fluxes transversely to the direction of current flowing through the focusing and tracking coils3and4.

A vertical force is generated from the current flowing through the focusing coil3, so that the lens holder2moves the objective lens1in a focusing direction.

Likewise, a horizontal force is generated from the current flowing through the tracking coil4, so that the lens holder2moves the objective lens1in a tracking direction.

Here, due to the movement of the driving portion formed of the objective lens1and the lens holder2, the wire springs impart elasticity on the lens holder2, so that the driving portion generates fine vibrations.

The vibration distortions thus generated are absorbed by the viscoelastic material16, so that the vibrations from the driving portion are reduced or eliminated.

However, the assembly process of radiating ultraviolet rays onto the damper material16to obtain a predetermined viscoelasticity thereof, following the filling of the liquid damper material16in the filling hole14, requires much equipment and manpower. In addition, the assembly process suffers from the problems of having to quickly inject the filling hole14with damper material16, and non-uniformity in performance of the damper material16.

For example, because damper material16for filling into four separate filling holes14in the wire holder9is contained in a single syringe (which must fill the holes one by one), the quantity of damper material16filling each of the filling holes14may be excessive or insufficient, and bubbles may be formed inside the filling holes14, so that the hardness may vary, causing the damping characteristics of the damper material16in each hole to be non-uniform.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an optical pick-up actuator that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an optical pick-up actuator with a lens holder and wire springs that are solidly coupled, by applying a uniform amount of adhesive for coupling each of the wire springs to the lens holder.

Another object of the present invention is to provide an optical pick-up actuator with damper material that has uniform performance characteristics for reducing or eliminating vibration distortion in the wire springs, and that can quickly be injected into a wire holder.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided an optical pick-up actuator including: a lens holder including an objective lens; a magnetic circuit for moving the lens holder; a wire spring coupled at one end thereof to a side of the lens holder, the wire spring for supporting the lens holder; a wire holder fixing the other end of the wire spring; and a damper material receptacle defining an insert hole and a through-hole through which the other end of the wire spring is inserted and passes, the damper material receptacle for holding a predetermined damper material that absorbs vibrations imparted on the wire spring, wherein the damper material defines an injecting hole, through which the damper material is injected, separately from the insert hole and the through-hole.

In another aspect of the present invention, there is provided an optical pick-up actuator including: a lens holder including an objective lens, a focusing coil and a tracking coil that are respectively wound with wire, and a fixing protrusion; magnets installed to respectively face the focusing coil and the tracking coil; a wire spring coupled at one end thereof to the fixing protrusion, the wire spring for connecting the focusing coil and the tracking coil; a wire holder including a damper material receptacle through which the other end of the wire spring passes, the damper material receptacle for holding a predetermined damper material for enclosing a predetermined portion of the wire spring that is passed therethrough; and a circuit board formed on a rear surface of the wire holder, for connecting to the other end of the wire spring that passes through the damper material receptacle, wherein an injecting hole for injecting damper material is formed in a top surface of the damper material receptacle.

In a further embodiment of the present invention, there is provided an optical pick-up actuator including: a base; a wire holder provided at a side of the base; a lens holder installed at an upper portion of the base, including an objective lens, and having a fixing protrusion forming an adhesive chamber provided on either end thereof; a magnetic circuit for allowing the lens holder to move; a wire spring with one end thereof passing through the adhesive chamber of the fixing protrusion and coupled to the lens holder with an adhesive, and the other end thereof fixed to the wire holder; and a damper material receptacle through which the other end of the wire spring passes, for holding a predetermined damper material that absorbs vibrations generated by the movement of the lens holder.

The above-structured optical pick-up actuator allows adhesive for coupling a lens holder to wire springs to be injected accurately into predetermined locations without dripping elsewhere, so that a firmer coupling of the lens holder and the wire springs can be realized, and a fixed amount of adhesive is used, preventing waste of adhesive.

Also, the damper material that eliminates vibration distortion on the wire springs can be injected quickly and evenly into the filling portions of the wire holder, so that the damping effectiveness of the driving portion has a uniform range of movement, and the assembly process of the optical pick-up actuator becomes simpler.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 4is a perspective view of an optical pick-up actuator according to an embodiment of the present invention.

Referring toFIG. 4, an optical pick-up actuator according to the present invention includes a base100, a driving portion installed to be supported by the base100, and a magnetic circuit for prompting the driving portion to be driven in focusing and tracking directions.

The driving portion is formed of a lens holder110with an objective lens101. The magnetic circuit includes wire-wound focusing and tracking coils102and103to one side of the lens holder110, and magnets104installed oppositely to the focusing and tracking coils102and103.

When a current is applied to the focusing coil102or the tracking coil103, a Lorentz force is generated between the magnet104and the focusing or tracking coil102or103, so that the driving portion moves in a focusing direction or a tracking direction.

The optical pick-up actuator includes a wire spring150(of which an end is coupled to one side of the lens holder110), a wire holder120(to which the other end of the wire spring150is fixed), and a circuit board130formed on the rear surface of the wire holder120.

The wire spring150is made of a rigid metal material that conducts electricity, with one end thereof coupled to a fixing protrusion113formed on one side of the lens holder110and the other end thereof connected to the circuit board130.

A substrate111is respectively installed on either side surface of the lens holder110, and the wire spring150is soldered to the substrate111, thereby electrically connecting the focusing coil102and the tracking coil103.

The wire spring150conducts a current from the circuit board130to the focusing and tracking coils102and103, thereby enabling the driving portion to move in focusing and tracking directions.

Although the wire spring150according to embodiments of the present invention is installed in quadruplicate (with two on each side of the lens holder110connecting the focusing coils102and the tracking coils103), the wire spring150may be singular or provided in triplicate on either side of the lens holder110.

A tilting coil for driving the lens holder110in a tilting direction may also be provided, in which case the number of wire springs150may be altered.

Specifically, the present invention is not limited in its number of installed wire springs150, which function to conduct current respectively to the focusing and tracking coils102and103when the current is applied to the wire springs150.

Also, an insert hole121and a through-hole122are formed in the wire holder120, through which the wire springs150pass and are connected to the circuit board130. The insert hole121and the through-hole122may be formed in different ways, depending on the number of wire springs150installed. That is, a plurality of wire springs150may be made to pass through one insert hole121and one through-hole122.

The opposite end of the wire spring150passes through a damper material receptacle124between the insert hole121and the through-hole122. The damper material receptacle124defines an injecting hole123thereabove for injecting a predetermined damper material140. The damper material receptacle124may be formed as a single hole that has a plurality of wires disposed within the damper material receptacle.

After the opposite end of the wire spring150passes through the insert hole121and the damper material receptacle124, it is passed through the through-hole122and is connected to the circuit board130.

The damper material140may be an ultraviolet hardened viscoelastic material, which is injected through the injecting hole123into the damper material receptacle124in liquid form, and then hardened through ultraviolet ray emission.

Because the injecting hole123of the damper material receptacle124is formed in an upward direction, the damper material140may be quickly and uniformly filled into the damper material receptacle124.

The damper material receptacle124may be formed of a material that transmits ultraviolet radiation. In this case, after the filling of the liquid damper material140into the damper material receptacle124, when ultraviolet rays are emitted, they will be transmitted through the walls of the damper material receptacle124to the damper material140, to more easily harden the damper material140.

Because the wire spring150is enclosed by damper material140in the damper material receptacle124(which the wire spring150is passed through), the damper material140can absorb vibration distortions incurred on the wire spring150.

That is, when the wire spring supports the driving portion, and the driving portion moves in a focusing or tracking direction, imparting vibration distortions on the wire spring150, these vibration distortions can be absorbed and cancelled by the damper material140.

Because the wire spring150is enclosed by the hardened damper material140in the damper material receptacle124that it has passed through, the wire spring150may be firmly fixed to the wire holder120.

FIG. 5is a perspective view of a wire holder of an optical pick-up actuator according to an embodiment of the present invention.

A detailed description of the wire holder120and the damper material receptacle124will be given, with reference toFIG. 5.

Referring toFIG. 5, the wire holder120is provided on one side of the base100. Here, the wire holder120may be integrally formed with the base100, or may be separately formed and fixed to one side of the base100.

The base100forms a mounting receptacle105for receiving the driving portion in a suspended state, and a first supporting portion106for installing one of a pair of magnets104.

The wire holder120forms a second supporting portion125for supporting the other of the pair of magnets104. A damper material receptacle124is formed on either side of the second supporting portion125.

While the damper material receptacle124is formed integrally with the wire holder120in the present embodiment, in other embodiments, the damper material receptacle124may be formed separately and then installed at either side of the wire holder120.

A yoke107is installed between the first and second supporting portions106and125and the magnets104, for inducing a magnetic flux generated by the magnets104.

The damper material receptacle124is formed in a region through which the opposite end of the wire spring150passes and is connected to the circuit board130, and includes an injecting hole123formed in an upward direction to create a filling hole for damper material140to pass therethrough.

An insert hole121, for inserting the wire spring150through, is formed at the front surface of the damper material receptacle124. A through-hole122(for the wire spring150to pass through and be connected to the circuit board130) is formed in-line with the insert hole121on the rear surface of the damper material receptacle124.

When a liquid damper material140is injected through the injecting hole123into the damper material receptacle124, the damper material140can be quickly and uniformly injected because it is filled from the bottom of the damper material receptacle124to the top thereof.

The damper material140may be evenly filled in the insert hole121and the through-hole122, which are respectively disposed at predetermined heights.

When the liquid damper material140is filled in the insert hole121and through-hole122at the front and rear surfaces of the damper material receptacle124, the damper material140does not flow out from the insert hole121and the through-hole122due to the surface tension of the liquid, and maintains equilibrium in a filled state.

When ultraviolet rays are emitted onto the damper material receptacle124with the liquid damper material140filled therein, the emitted ultraviolet rays pass through the walls of the damper material receptacle124to the damper material140, so that the damper material140can be easily hardened.

FIG. 6will be referred to in the description of the operation of the optical pick-up actuator according to the present invention.

The circuit board130provided on the rear surface of the wire holder120supplies a current to the wire spring150, and as a result, the driving portion moves in a focusing or tracking direction.

That is, when a current is supplied from the circuit board130through the wire spring150to the focusing coil102, the driving portion moves in a focusing direction by means of a Lorentz force generated between the focusing coil102and the pair of magnets104.

Also, when a current is supplied from the circuit board130through the wire spring150to the tracking coil103, the driving portion moves in a tracking direction by means of a Lorentz force generated between the tracking coil103and the pair of magnets104.

Because the above-described moving of the driving portion in focusing and tracking directions occurs up to several hundred times within a very short duration, torsion and other vibration-induced distortions are incurred on the wire spring150that supports the driving portion.

The vibration distortion on the wire spring150is transferred along the wire spring150to the wire holder120.

Thus, the vibration distortion that is transferred to the wire holder120is absorbed by the damper material140that has been injected into the damper material receptacle124and hardened, and which encloses a portion of the wire spring150.

Accordingly, the vibration distortion that is generated by the focusing and tracking movement of the driving portion and transferred to the wire spring150is absorbed by the damper material140, so that the movement of the driving portion in a focusing direction and a tracking direction is not affected by the vibration distortion. Thus, the driving portion can operate normally.

In an optical pick-up actuator according to the present invention, the movement of the driving portion in a focusing direction and a tracking direction is not affected by vibration-induced torsion or distortion, and performs in a normal manner.

Also, the process of filling the damper material140in the optical pick-up actuator according to the present invention can be quickly executed due to the injecting hole123being formed from the top down. Thus, the damper material receptacle124, the insert hole121, and the through-hole122can quickly be filled.

Additionally, the process of filling the damper material140in the optical pick-up actuator according to the present invention can evenly fill the damper material receptacle124, the insert hole121, and the through-hole122, so that an even damping of the driving portion can be obtained.

FIG. 7is a perspective view of an enlarged section of an optical pick-up actuator according to an embodiment of the present invention showing the coupling of wire springs to the lens holder without having any adhesive applied thereto.

Referring toFIG. 7, a substrate111is respectively installed on the upper end at either side of the lens holder110. The substrates111are fixed to the tops of the wire springs150with solder112that electrically connects and fixes the wire springs150to the substrates111.

Two fixing protrusions113are provided on each end of the lens holder110. The fixing protrusions113fix the wire springs150to the lens holder110.

Furthermore, the fixing protrusion113forms an adhesive chamber114that is opened at the top. The adhesive chamber114is a portion in which an adhesive for fixing ends of the wire spring150to the lens holder110is applied, and is formed through the fixing protrusion113.

A wire through-hole115, through which one end of the wire spring150passes, extends through the fixing protrusion113. The wire through-hole115passes through the fixing protrusion113so that it communicates with the adhesive chamber114.

In further detail, the wire through-hole115is formed with a diameter through which one end of the wire spring150may pass—that is, the diameter of the wire through-hole115is the same as or slightly larger than the diameter of the wire spring150.

Of course, the design must be made so that adhesive filled in the adhesive chamber114does not flow out from the gaps between the wire through-holes115and the wire springs150. To properly design the size of the gaps, the viscosity of the adhesive must be taken into account.

Excluding the upper surface and the surface in which the wire through-hole115is formed, the remaining surfaces of the fixing protrusion may be sealed.

A detailed description of the coupling of the lens holder110and the wire spring150in the optical pick-up actuator according to embodiments of the present invention will be provided below.

First, one end of the wire spring150is passed through the wire through-hole115of the fixing protrusion113, to pass through the fixing protrusion113itself. Then, the one end of the wire spring150that has passed through the fixing protrusion113is soldered to the substrate111and electrically connected thereto.

The end of the wire spring150that has passed through the fixing protrusion113also passes through the adhesive chamber114inside the fixing protrusion113. This is explicitly shown inFIG. 7. In this state, adhesive is applied within the adhesive chamber114.

When adhesive is applied within the adhesive chamber114, it fills the adhesive chamber114. The wire through-hole115communicating with the adhesive chamber114is designed to prevent adhesive from leaking through the gap between it and the wire spring150, and a predetermined amount of adhesive may fill the adhesive chamber114.

If adhesive is filled to a predetermined level in the adhesive chamber114, for example, to the edge of the entrance of the adhesive chamber114, a predetermined quantity of adhesive can be uniformly used for each adhesive chamber114.

When adhesive is applied within the adhesive chamber114and hardened, the one end of the wire spring150that passes through the wire through-hole115and the adhesive chamber114is coupled to the fixing protrusion113, or the lens holder110through the adhesive.

When the lens holder110is coupled to one end of the wire spring150, the lens holder110is supported indirectly by the wire holder120through the wire springs150, and the lens holder110is elevated from the top of the base100.

In the optical pick-up actuator according to the present invention, when adhesive is applied to couple the one end of the wire spring150to one side of the lens holder110, the adhesive may be applied into the adhesive chamber114opened at the top of the fixing protrusion113.

Because the fixing protrusion113is sealed on all sides with the exception of the side with the wire through-hole115formed and the open side of the adhesive chamber114, the adhesive that is applied to the adhesive chamber114does not leak out, so that the end of the wire spring150is more firmly fixed to the fixing protrusion113.

Also, by applying adhesive to the adhesive chamber114in order to couple the one end of the wire spring150to the lens holder110, a uniform amount of adhesive is used in each adhesive chamber114, preventing waste of adhesive.

FIG. 8is a perspective view of an optical pick-up actuator according to a modification of an embodiment of the present invention.

Compared to the above embodiments, there is only one change, that being the addition of a cover, so that the descriptions of the other elements in previous embodiments may be revisited by referring to the same reference numbers of the corresponding elements.

Referring toFIG. 8, in the optical pick-up actuator according to the present embodiment, after liquid damper material is applied to the damper material receptacle124, a cover160for sealing the injecting hole123is added.

The cover160has the shape of a plate for covering the injecting hole123, the driving portion, and a portion of the base100, and may be snap fitted or fixed to the supporting portions106and125and the wire holder120using bolts or other fastening members.

Accordingly, before the liquid damper material that is injected into the damper material receptacle124is hardened by ultraviolet ray emissions, it is prevented from leaking to the outside of the damper material receptacle124. Also, the entry of foreign substances into the damper material receptacle124can be prevented.

The cover160may have an adhesive applied to a portion thereof that contacts the injecting hole123in order to completely seal the injecting hole123. In this case, the liquid damper material that is injected into the damper material receptacle124is completely sealed and prevented from leaking to the outside.

Thus, the liquid damper material is injected into the damper material receptacle124, and the cover160having adhesive applied to portions thereof that contact the injecting hole123, completely seals the injecting hole123when it is installed. Afterward, ultraviolet rays for hardening the liquid damper material are emitted.

The ultraviolet rays are transmitted through the wire holder120to harden not only the liquid damper material injected into the damper material receptacle124, but also the adhesive applied to regions of the cover160contacting the injecting holes123.