JP2529393Y2 - Optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention relates to an optical pickup device used for an optical disk player such as a compact disk.

[Prior Art] As an optical pickup device used in a conventional optical disk player such as a compact disk, there is an optical pickup device having a configuration shown in FIG. FIG. 4 is a top view of the optical pickup device.

The optical pickup device 1 shown in FIG. 1 includes a lens holder 8 on which an objective lens 2 for transmitting and receiving light to and from a compact disc (not shown) is mounted on an upper surface, and magnets 3, 3 mounted on one surface of the lens holder 8. When,
A support mechanism 4 for supporting the magnets 3, 3 in a displaceable manner.
And a yoke which is arranged opposite to the magnets 3 and respectively, and is wound with two windings 5 and 6 for tracking correction and focus correction, respectively, which intersect each other at the opposing surfaces.
7,7 are provided.

The support mechanism 4 includes a mold spring 4a attached to one end of the lens holder 8 and the other end attached to a fixed portion in a disc player.

With the optical pickup device 1 having the above configuration,
The objective lens 2 can be displaced by the magnetic force generated by the energization of the windings 5 and 6, thereby performing focusing control and tracking control.

[Problem to be Solved by the Invention] In the above structure, a magnetic attractive force acts between the magnet 3 and the yoke 7 so as to maintain a neutral position between the two. In this state, when the tracking correction winding 6 is energized, the magnet 3 is displaced in the direction of arrow A by the electromagnetic force generated by the energization.

However, a magnetic repulsive force (a force for moving the magnet 3 further away from the neutral position (a)) exists between the opposing magnet 3 and the yoke 7, thereby affecting the spring constant of the mold spring 4a. Problems have been identified.

Here, the negative spring constant (spring constant in the direction of moving the magnet away) due to the repulsive force is K ₁ , and the positive spring constant of the molded spring 4a (spring constant in the direction of returning the magnet to the neutral position) is K ₁ . Assuming that K ₂ and the appropriate spring constant of the entire elastic support system are K ₀ , K ₀ = K ₁ + K ₂ . Thus in consideration of the spring constant of the magnetic repulsion, to set the entire system for proper spring constant, the spring constant of the mold spring 4a is, satisfies _{K 2 = K 0 -K 1 (} K 1 <0) It is necessary to set as follows.

However, the mold spring 4a is used at a temperature between about 20 ° C. and the upper limit is usually about 70 ° C. When comparing the Young's modulus at room temperature with the Young's modulus near the upper limit, the Young's modulus near the upper limit is The value is about half of that at room temperature. On the other hand, a negative spring constant K ₁ by the magnetic repulsive force is constant regardless of the temperature difference.

Therefore, the mold spring 4a at a certain temperature
Even if the spring constant K _{0 of the} entire system is appropriately set based on the spring constant K _{2 of the above} , since the spring constant K ₂ changes depending on the temperature, the influence of the spring constant K ₁ of the magnetic repulsion on the whole system is affected. There has been an unsolved problem that the number has increased extremely and it is extremely difficult to accurately perform focusing control and tracking control. Such a problem is not limited to the above-described mold spring 4a, but is also a problem common to all spring members of this type.

Accordingly, the present invention provides an optical pickup device in which the magnetic repulsive force is canceled by the component force of the elastic force of the elastic support member, thereby eliminating the influence of the spring constant due to the repulsive force, so that focusing control and tracking control can be accurately performed. Aim.

[Means for Solving the Problems] According to a configuration of the present invention for achieving the above object, a lens holder for holding an objective lens facing an optical disk is movably supported by an elastic support member extending from a fixed portion, and a lens is provided. A winding for correction driving is provided on one side and a magnet is provided on the other side between the facing portion facing the holder from the side opposite to the side supported by the elastic support material and the lens holder, and the magnet provides a lens. An optical pickup device in which the holder is magnetically attracted in the direction of the facing portion, wherein the magnetic attraction force is F, and the displacement amount when the center of the lens holder is displaced from the center of the facing portion is a; Sometimes, the magnetic repulsive force f, which attempts to displace the lens holder in a direction perpendicular to the magnetic attraction F and further away from the center by the magnetic force of the magnet, f, The elongated support of the serial elastic support member when as L, in which the relational expression f / a = F / L is characterized in that each value to stand at least approximate value to be set.

[Operation] In the above-described means, an attractive force is generated between the magnet on the lens holder side and a magnetic body such as a yoke on the opposing portion, or between the magnet on the rear side and the magnetic body such as a winding on the lens holder side. In the working structure, the magnetic repulsive force for moving the lens holder away from the neutral position in a direction perpendicular to the attractive force can be canceled by the magnetic attractive force. In other words, the support structure is such that the component force of the magnetic attraction force returns the lens holder to the neutral position when the lens holder is displaced, and the spring constant due to this component force and the spring constant due to the magnetic repulsion are cancelled. This condition is expressed as f / a = F where F is the magnetic attraction force, a is the displacement amount of the lens holder, f is the magnetic repulsion force generated between them, and L is the length of the elastic support member. That is, each value is set so that the relational expression of / L is at least approximately satisfied.

[Embodiment] Hereinafter, the present invention will be described with reference to the drawings.

1 (A) is a plan view of an optical pickup device as one embodiment, FIG. 1 (B) is an explanatory diagram schematically showing a supporting state and the action of force, and FIG. 2 is a diagram of the optical pickup device shown in FIG. It is an external appearance perspective view.

The optical pickup device 9 shown in FIG. 2 has a lens holder 11 on which an objective lens 10 for transmitting and receiving light to and from an optical disk D arranged on the upper surface is mounted, and is mounted on one side surface of the lens holder 11. A rectangular magnet 12 and four elastic support members 13a made of a spring member
, A yoke 14 disposed at an opposing portion facing the magnet 12, and two windings 15 and 16 wound around the yoke 14 in directions intersecting with each other. Reference numeral 15 is for focus correction drive, and reference numeral 16 is for tracking correction drive.

The supporting member 13a constituting the supporting mechanism 13 has side surfaces 11c, 11c orthogonal to the mounting surface 11a of the magnet 12 shown in FIG.
One end is attached to each of the four protrusions 11b formed so as to protrude therefrom, and the other end is fixedly attached to the optical disc player 20. As a result, the lens holder 11 moves the magnetic field H generated between the magnet 12 and the yoke 14.
Is supported so as to be freely displaceable in a plane substantially perpendicular to the plane of the drawing including the direction (direction of arrow A) intersecting with the plane.

Note that one end of the support member 13a may be attached not only to the protrusion 11c, but also to a surface 11d of the lens holder 11 opposite to the attachment surface 11a of the magnet 12, so that the side surface 11c itself is not interposed via the protrusion 11b. It may be directly attached to.

The yoke 14 arranged on the facing part of the lens holder 11 is a plate-like member made of a magnetic material. The yoke 14 is provided so that the magnetic flux from the magnet 12 passes through the windings 15 and 16 efficiently. Therefore, the two windings 15, 1
An electromagnetic force acts on the lens holder 11 by the current 6 and the magnetic field H crossing the current, and the lens holder 11 is driven in the focus correction direction or the tracking correction direction. On the other hand, since the yoke 14 and the magnet 12 are arranged close to each other, magnetic attraction acts between them.

Here, as shown in FIG. 1B, the magnetic attraction force for attracting the magnet 12 and the lens holder 11 to the yoke 14 is F, and the magnet 12 and the yoke 14 when the lens holder 11 is displaced in the tracking correction direction A, for example. Where a is the displacement amount from the neutral position 0, f is the magnetic repulsive force generated between the two at a time perpendicular to the magnetic attraction force F, and L is the support length of the support member 13a. Each value is set so that the relational expression of f / a = F / L is satisfied at least approximately.

Here magnetic attraction force F is extra spring constant for returning the lens holder to the neutral position and K _3. The magnetic attraction acting on the four support members 13a is F / 4. When the displacement angle of the support member 13a when the displacement amount of the lens holder is a is θ, at this time, each support member
The component force F in the direction of returning the magnetic attraction force to the neutral position at 13a
_1/4 is represented by F _1/4 = (1/4) · F · sin θ · cos θ.

Therefore, the value of the spring constant K ₃ by the magnetic attractive force F,
In each elastic support member 13a, K ₃ = F _1/4 / a = (1/4) · F · sin θ · cos θ / L · sin θ = (F / 4L) · cos θ ≒ F / 4L spring constant K ₃ of a total member 13a becomes = F / L.

On the other hand, if the spring constant due to the magnetic repulsion f is K ₄ ,
This K ₄ is represented by K ₄ = f / a. Here, the spring constant K ₄ =
From the condition that the K _3, the relational expression of the f / a = F / L is derived.

The operation and effect of the present invention having the above configuration will be described with reference to FIGS. 3 (a) and 3 (b).

6A and 6B, the tracking correction winding 16 is used.
Is energized, the lens holder 11 will be described on the assumption that is displaced to A ₁ along the paper surface, in a direction perpendicular been energized coil 15 for focus correction lens holder 11 and the paper The same applies to the case of displacement, and the description is omitted here.

As shown in FIG. 3A, when the winding 16 is not energized, the magnet 12 and the yoke 14 are in the neutral position.

When energized winding 16 in this state, the electromagnetic force generated due to the energization, the magnet 16 is displaced in the arrow A ₁ direction, as shown in example FIG. (B). The displacement at this time is defined as a. The lens holder 11 by magnetic repulsion f perpendicular to the magnetic attractive force F is in the displacement state tries displaced further in the arrow A ₁ direction.

However, in this embodiment, since the respective values are set so that the relational expression of f / a = F / L is satisfied at least in an approximate value, the value of the magnetic attraction force acting in the opposite direction to the magnetic repulsion force is calculated. A force is generated, which acts to pull the magnet 12 back to the neutral position (a), that is, the center axis O. Thereby, the canceling magnetic repulsion is almost canceled by the magnetic attraction.

With the invention described in detail above, the magnet 12 and the yoke 14
This effect can be eliminated even if a magnetic repulsion corresponding to the amount of relative displacement occurs between the two. Therefore, it is not necessary to set the spring constant of the support member 13a to an unnecessarily large value, and even if there is a temperature change, the effect can be reduced. Therefore, the response of the control can be improved.

The present invention is not limited to the above embodiment,
Various modifications can be made within the scope of the gist.

In the above-described embodiment, an example in which a magnet is attached to the lens holder is illustrated. However, a winding made of a magnetic material may be attached to the lens holder, and the magnet may be fixed to the facing portion. In this case, magnetic attraction and magnetic repulsion act between the magnet and the winding.

Even in the case of such a configuration, the same operation and effect as in the above embodiment can be obtained.

[Effects of the Invention] According to the present invention described in detail above, it is possible to provide an optical pickup device used in an optical disk player that can appropriately perform focusing control and tracking control properly even when the ambient temperature changes.

[Brief description of the drawings]

1 (A) is a plan view of an optical pickup device as one embodiment, FIG. 1 (B) is an explanatory diagram showing the relationship between displacement and force, and FIG. 2 is an external perspective view of the optical pickup device shown in FIG. Figure,
3 (a) and 3 (b) are explanatory diagrams showing an operation state, and FIG. 4 is an explanatory diagram of a conventional optical pickup device. 10: Objective lens, 11: Lens holder, 12: Magnet, 13a: Support member, 14: Yoke, 15, 16 ... Winding.

Claims (1)

(57) [Scope of request for utility model registration] A lens holder for holding an objective lens facing an optical disk is movably supported by an elastic support member extending from a fixed portion, and faces the lens holder from a side opposite to a side supported by the elastic support member. An optical pickup device in which a winding for correction driving is provided on one side and a magnet is provided on the other side between the facing portion and the lens holder, and the lens holder is magnetically attracted to the facing portion by the magnet. The magnetic attraction force is F, the displacement amount when the center of the lens holder is displaced from the center of the facing portion is a, and at this time, the lens holder is orthogonal to the magnetic attraction force F by the magnetic force of the magnet and When the magnetic repulsive force to be displaced in the direction away from the center is f and the supporting length of the elastic supporting member is L, the relational expression of f / a = F / L is at least. An optical pickup device characterized in that each value is set so as to establish an approximate value.