JPH11175994A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device having a very small biaxial actuator wherein secondary resonance vibration generated in a holder made of a plastic material is prevented from being transmitted to an objective lens. SOLUTION: In an optical pickup device having a biaxial actuator wherein a holder 2 made of a plastic material serves also as the bobbin of a driving coil and an objective lens 8 is mounted on the center part of the holder 2, a slit hole 14 is formed to pass through a holder part between both side face parts 2a of the holder 2 and the objective lens 8 so as to approach the node 2b of secondary resonance vibration, and vibration by secondary resonance generated in both side face parts 2a of the holder 2 is cut off by the slit hole 14 to be prevented from being transmitted to the objective lens 8 side.

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 having a miniaturized two-axis actuator for recording / reproducing a recording information medium such as an optical disk, and more particularly, to an optical pickup device equipped with an objective lens and a driving coil. By forming a slit hole in the holder of the biaxial actuator, the vibration caused by the secondary resonance of the holder is not transmitted to the objective lens.

[0002]

2. Description of the Related Art FIG. 3 is a plan view of a suspension type biaxial actuator. The holder is indicated by reference numeral 31. The holder 31 also serves as a bobbin of the drive coil, and a focus coil (not shown) is wound around the holder 31. Further, tracking coils 32 and 33 are provided in a state of being separated and wound on the front and rear surfaces of the holder 31 in two parts, and respective coil ends of the focus coil and the tracking coil are provided on side portions of the holder 31. A pair of upper and lower coil terminals 34, 34 (the lower coil terminals are not shown) are drawn out. An objective lens 35 is mounted at the center of the holder 31.

[0003] The holder 31 has a pair of upper and lower suspensions 36, 36 each consisting of four wires. The distal ends of the suspensions 36, 36 are fixed to fixing portions 37, 37 (both lower suspensions and fixing portions are not shown). The base end is fixed to a fixing block 38. Therefore, the holder 31 is held in a state of being horizontally suspended by the four suspensions.

In the two-axis actuator thus configured, yokes 39 and 40 erected from a pickup main body (not shown) are arranged in two front and rear spaces of a holder 31 and front surfaces of tracking coils 32 and 33, respectively. Yoke 4 with magnets 41 and 42 attached to its side
3, 44 are arranged.

In the above-described two-axis actuator, when the focus servo signal and the tracking servo signal are supplied to the focus coil and the tracking coil, the objective lens 35 and the holder 31 are driven in focus and tracking together with the holder 31 by electromagnetic action. Is reflected by pits on a disc (not shown), and the reflected light is converted into an electric signal to perform a recording / reproducing operation on the disc.

[0006]

However, since the two-axis actuator is driven at a high speed, vibrations are generated in the holder by secondary resonance. The mechanism of this secondary resonance vibration will be described with reference to the plan view of the holder shown in FIG.
The next resonance occurs most on both side surfaces 31a, 31a of the holder 31, and the both side surfaces 31a, 31a become resonance vibrations a that largely wave inward and outward as indicated by the dotted lines. The vibration “a” is transmitted from the side surfaces 31 a of the holder 31 to the objective lens 3.
5 is transmitted as vibration b, which has an undesirable effect on the servo operation of the objective lens 35.

As a method for solving this problem, a method has been adopted in which the structure of the holder is strengthened and the resonance frequency of the holder is designed to be higher than, for example, 30 kHz. However, this method is technically difficult, and the structure of the holder is difficult. If the strength is increased, including the selection of the plastic material to be used, the weight of the two-axis actuator increases, and conversely, there is a problem that the sensitivity decreases. Therefore, it is conceivable that the holder is made of a light metal material other than the plastic material. However, in the case of a lightweight two-axis actuator, it is technically very difficult to design the secondary resonance of the holder to 30 kHz or more. Difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has an ultra-compact size in which a holder is made of a plastic material so that vibration of secondary resonance generated in the holder is not transmitted to an objective lens. It is an object of the present invention to obtain an optical pickup device having the above two-axis actuator.

[0009]

In order to achieve the above-mentioned object, an optical pickup device according to the present invention is provided with a slit hole penetrating a holder portion between both side surfaces of the holder and the objective lens.

[0010] With this configuration, vibration occurs due to antinodes of secondary resonance on both side surfaces of the holder.
This vibration is blocked by the slit hole, and transmission of the vibration to the holder on the objective lens side can be prevented. In addition, since almost no vibration occurs on both side surfaces of the holder, the vibration due to resonance is transmitted to the objective lens side by connecting this node and the holder part on which the objective lens is mounted. There is no.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a biaxial actuator of an optical pickup device according to the present invention will be described with reference to a microminiature two-axis actuator.
This will be described with reference to the drawings, taking a shaft actuator as an example.

FIG. 1 is a perspective view showing an assembled state of a suspension type biaxial actuator in an optical pickup device according to this embodiment, and FIG. 2 shows a mechanism of secondary resonance of a holder.

In FIG. 1, reference numeral 1 denotes the whole of a two-axis actuator. The holder 2 also serves as a bobbin of the drive coil, and the holder is formed of a lightweight and impact-resistant plastic material. A focus coil 3 is wound around the holder 2, and tracking coils 5, 5 are provided in a state of being separately wound around cores 4, 4 on the front and rear surfaces of the holder 2. I have. The respective coil ends of the focus coil 3 and the tracking coils 5, 5 are led out to a pair of four coil terminals 6, 6, 7, and 7 provided on the side of the holder 2. And
An objective lens 8 is mounted at the center of the holder 2.

The holder 2 has suspensions 9, 9, and 10, 10 each composed of a pair of upper and lower wires, and each end of the suspension is fixed to a fixed arm 11, 11, and each end of the suspension is connected to a coil terminal 6, 6 and 7, 7 are electrically conductively connected. The base end of the suspension passes through damper members 13, 13 provided on the fixed block 12, and the suspensions 9, 9 and 10, 10 are conductively connected to power supply terminals (not shown) provided on the back side of the fixed block 12. . Thus, the holder 2 is held in a state of being horizontally suspended by the four suspensions.

The above-described two-axis actuator has the same configuration as the two-axis actuator shown in FIG. 3 described in the conventional example, but the present invention is different from the conventional example in that the two-axis actuator shown in FIG. Slit holes 14 penetrating between 2a, 2a and a holder portion on which the objective lens 8 is mounted;
14 is formed. That is, the side surfaces 2a, 2a of the holder 2 become so-called resonance antinodes a in which vibrations due to the secondary resonance undulate inward and outward, and slit holes are formed so as to correspond to the resonance antinodes a. .

Further, vibrations due to secondary resonance hardly occur on both side surfaces 2a of the holder 2, so-called nodes 2b, 2b.
2b, and a slit 14 is formed in a portion approaching the nodes 2b, 2b. Also, this section 2b, 2b
Are connected portions between the side portions 2a, 2a of the holder 2 and the holder portion on which the objective lens 8 is mounted.

That is, according to the present invention, even if the vibration a occurs due to the antinodes of the secondary resonance on both side surfaces 2a of the holder 2, the vibration a is blocked by the slit hole 14, and the vibration a is transmitted to the objective lens 8 side. Vibration transmission can be effectively reduced. Moreover, since the nodes 2b, 2b of the secondary resonance are portions where almost no vibration occurs, the nodes 2b, 2b
Vibration is hardly transmitted from b to the objective lens 8 side. As a result, only a very small vibration component occurs in the objective lens 8, and this vibration component is recorded / recorded by the objective lens.
It has no effect on the playback operation.

The present invention is not limited to the embodiment described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention.

If the width d of the slit hole 14 is too large, the strength of the side surfaces 2a of the holder 2 is reduced, so that the width d is adjusted in the design stage so as to be as narrow as possible.

It is preferable that the length e of the slit hole 14 is as close as possible to the nodes 2b, 2b of the secondary resonance. In this case, too close, the side surfaces 2a, 2a and the objective lens 8 are mounted. Since the connecting part with the holder part becomes too thin and the strength is reduced, it may be adjusted at the stage of designing the holder.

[0021]

As described above, according to the optical pickup device of the present invention, a slit is formed in the holder between the both sides of the holder of the biaxial actuator and the objective lens, so that the holder is formed in the holder. Vibration due to the generated secondary resonance can be prevented from being transmitted to the objective lens. Thereby, the vibration of the objective lens can be effectively suppressed without increasing the weight of the holder,
The sensitivity and performance of the two-axis actuator can be improved, and, for example, it is extremely suitable to be applied to a microminiature two-axis actuator such as a CD-ROM.

Further, according to the second aspect, the slit hole has a diameter of 2 mm.
By having a hole length close to the node of the secondary resonance vibration, since this node is a portion which is not affected by the secondary resonance vibration, two holes generated on both side surfaces of the holder are formed.
It is possible to adopt a configuration in which the vibration of the next resonance is not transmitted to the holder on which the objective lens is mounted, and the vibration of the objective lens can be effectively and reliably suppressed.

Further, in claim 3, the slit hole is formed by two holes.
By forming so as to correspond to the center of the antinode of the vibration of the next resonance, the vibration due to the secondary resonance of both side surfaces of the holder can be efficiently blocked by the slit holes.

[Brief description of the drawings]

FIG. 1 is a perspective view of an assembled state of a biaxial actuator in an optical pickup device of the present invention.

FIG. 2 shows a state of receiving a holder when a slit hole is formed.
This is the mechanism of vibration due to secondary resonance.

FIG. 3 is a perspective view of a conventional two-axis actuator in an assembled state.

FIG. 4 shows a mechanism of vibration due to secondary resonance received by a holder having no slit hole.

[Description of Signs] 1 Two-axis actuator, 2 holder, 2a Both side surfaces of holder, 2b Secondary resonance node, a Secondary resonance antinode, 3
Focus coil, 5 tracking coil, 8 objective lens, 9, 10 suspension, 12 fixing block, 14 slit hole

Claims (3)

[Claims] 1. A holder made of a plastic material on which an objective lens is mounted also serves as a bobbin of a drive coil. The objective lens is provided at a central portion of the holder. The holder is supported by a suspension and is movable in two axial directions. An optical pickup device having a biaxial actuator, wherein a slit hole is formed in a holder portion between both side surfaces of the holder and the objective lens, and a vibration due to secondary resonance generated in both side surfaces of the holder is formed as described above. An optical pickup device, wherein the optical pickup device is blocked by a slit hole so as not to be transmitted to the objective lens side. 2. The optical pickup device according to claim 1, wherein both side surfaces of the holder and a holder portion on which the objective lens is mounted are connected at a node portion which is not affected by vibration of a secondary resonance, and the slit is provided. An optical pickup device, wherein the hole has a length close to the node. 3. The optical pickup device according to claim 1, wherein the slit hole corresponds to the center of the antinode of the vibration of the secondary resonance.