JPH076921U - Objective lens drive - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an objective lens driving device capable of obtaining a sufficient vibration damping effect irrespective of the temperature change of the surrounding environment. A sheet body 10 in which a focus drive coil 11 and a tracking drive coil 12 are formed integrally with an objective lens holder 1 on which an objective lens 2 is mounted.
Is provided with a coil holding unit 20. A cut portion 22 is provided near the objective lens holder 1 of the coil holding portions 20 and 20 so as to separate the objective lens holder 1 and the balancer 3. The vibration from the objective lens holder 1 is cut by the cut portion 22 and is not transmitted to the objective lens 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an objective lens driving device used in an optical disc device or the like.

[0002]

[Prior art]

 An optical pickup used in an optical disc device or the like has an object lens driving device for always focusing a light beam emitted from a laser device or the like on a predetermined recording track on the recording surface of the optical disc. The objective lens driving device consists of a focus driving coil and a focusing magnet for driving the objective lens in the optical axis direction, and a tracking direction driving unit for driving the objective lens in a direction orthogonal to the optical axis. It consists of a drive coil and a drive unit in the tracking direction, which is composed of a tracking magnet.

FIG. 9 shows a conventional schematic structure of an optical pickup. 1 is an objective lens holder, 2 is an objective lens placed at a position away from the center O of the objective lens holder 1, and 3 is an objective lens holder. The balancer is attached to the objective lens holder 1 at a position opposite to the center O in order to balance the weight of No. 1. A focus drive unit and a tracking drive unit are provided at predetermined positions around the objective lens holder 1. In an optical pickup having such a structure, particularly when controlling the focus direction, the objective lens 2 is integrated with the objective lens holder 1 by the action of the focus magnet when a drive current is passed through the focus drive coil. Since it is driven in the optical axis direction as indicated by the arrow along O, focus control can be performed.

By the way, in performing such focus control, when the objective lens holder 1 is driven, high-order resonance due to bending vibration occurs at a frequency of several KHz or more, and the objective lens 2 vibrates abnormally. However, it is difficult to drive the objective lens 2 accurately. For this reason, conventionally, improvement measures have been proposed as disclosed in Japanese Patent Laid-Open No. 3-144924. As shown in FIG. 7, one of the means is to attach a balancer 3 to the objective lens holder 1 through an adhesive material 4 such as a double-sided adhesive tape, and the action of the adhesive material 4 causes the higher order resonance. The idea is to absorb the vibration caused by. In this case, the balancer 3 functions as a vibration damping member that reduces resonance. Alternatively, as shown in FIG. 8, a counterweight 5 acting as a vibration damping member is attached to the balancer 3 attached to the objective lens holder 1 via the adhesive material 4, and the action of the adhesive material 4 causes higher resonance. There is also an idea to absorb the vibration caused by.

[0005]

[Problems to be solved by the device]

 However, since the pressure-sensitive adhesive material 4 used to absorb the vibration due to higher-order resonance together with the balancer 3 and the counterweight 5 has a temperature characteristic, its viscosity changes according to the temperature change of the ambient environment. Since it changes, the vibration damping effect varies, and especially at low temperatures, the viscosity becomes smaller (harder), so there is a problem that the vibration damping effect becomes smaller.

The present invention has been made in consideration of the above problems, and an object thereof is to provide an objective lens driving device which can obtain a sufficient vibration damping effect regardless of the temperature change of the surrounding environment. It is a thing.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention attaches a balancer to an objective lens holder on which an objective lens is mounted so that its attachment surface is parallel to the vibration resonance direction due to control drive of the objective lens, and a focus drive coil. In an objective lens driving device integrally provided with a coil holding portion for holding a sheet body on which a tracking drive coil is formed, a cut portion is provided in the coil holding portion of the objective lens holder including the balancer. It is what

Another aspect of the present invention is characterized in that the cut portion separates the objective lens holder and the balancer in the coil holding portion.

Another aspect of the present invention is characterized in that the cut portion is provided in the vicinity of the objective lens holder.

[0010]

[Action]

 According to the configuration of the present invention described in claim 1, since the cut portion is provided in the above-mentioned coil holding portion of the objective lens holder including the balancer, vibration from the objective lens holder can be cut by this cut portion. Therefore, abnormal vibration of the objective lens can be suppressed. Therefore, a sufficient damping effect can be obtained.

According to the configuration of the present invention as set forth in claim 2, by providing the cut portion so as to separate the objective lens holder and the balancer in the coil holding portion, the same operation as in claim 1 can be achieved. it can.

According to the configuration of the present invention as set forth in claim 3, by providing the cut portion near the objective lens holder, the same operation as in claim 1 can be performed.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing an embodiment of an objective lens driving device of the present invention, in which an objective lens holder 1 is rotatable around a fixed shaft and movable along the fixed shaft by inserting a shaft hole 7 into the fixed shaft. Supported as possible. An objective lens 2 is attached to the objective lens holder 1 with its optical axis parallel to the shaft hole 7. A balancer 3 is attached to the objective lens holder 1 on the opposite side of the objective lens 2 around the shaft hole 7 by a fixing means without using an adhesive material 4.

The objective lens holder 1 has coil holding portions 20, 20 which are symmetrical with respect to a line connecting the center of the shaft hole 7 and the center of the objective lens 2 and which are concentric with the shaft hole 7 and which are partially cylindrical. Then, on the outer peripheral surfaces of the coil holding portions 20, 20, a sheet body 10 is attached by adhesion, in which a focus drive coil 11 and a tracking drive coil 12 are juxtaposed on an insulating sheet. In the vicinity of the objective lens holder 1 of the coil holding portions 20, 20, a cut portion 22 is provided so as to separate the objective lens holder 1 and the balancer 3. The sheet body 10 has a length from the one coil holding portion 20 to the other coil holding portion 20 through the back surface portion of the balancer 3, and has a cylindrical shape along the partial cylinder of the coil holding portions 20 and 20. None, the intermediate portion 13 in the longitudinal direction of the sheet body 10 is flat along the back surface portion of the balancer 3. Reference numeral 21 is an adhesive for fixing the sheet body 10 to the coil holding portion 20.

Magnets 6, 6 are fixed by yokes 9, 9 on the outer peripheral side of the arcuate portion of the sheet body 10 along the arcs of the coil holding portions 20, 20. The yokes 9, 9 and the magnets 6, 6 are formed in an arc shape concentric with the arc of the sheet body 10, and the inner peripheral surface of the magnets 6, 6 and the outer peripheral surface of the arc-shaped portion of the sheet body 10 have a predetermined gap. Facing each other. The magnet 6 is integrally formed with, for example, a resin binder. The magnet 6 is divided by a gap 8 into a focusing magnet 6a and a tracking magnet 6b. The focusing magnet 6a is magnetized so that the N pole and the S pole are lined up in the axial direction, while the tracking magnet 6b is magnetized in a direction orthogonal to the magnetization direction of the focus magnet 6a. A north pole and a south pole are formed in the circumferential direction. As described above, the magnets 6a and 6b are integrally molded and arranged on a continuous common surface.

The focusing magnet 6 a of each magnet 6 faces the focusing drive coil 11 of the sheet body 10, and the tracking magnet 6 b faces the tracking drive coil 12 of the sheet body 10. The yokes 5 and 5 are also arranged on the inner peripheral side of the coil holding portions 20 and 20, and the outer peripheries of the respective yokes 5 and 5 are formed in arcs concentric with the arcs of the yokes 20 and 20. The intermediate portion 13 of the sheet body 10 is formed with terminals for connecting the drive coils 11 and 12 to an external circuit.

Next, a specific example of the sheet body 10 having the drive coils 11 and 12 will be described with reference to FIG. The sheet body 10 is composed of two sheet body bodies 10a and 10b. Focus element drive coils 11 and 11 and tracking drive coils 12 and 12 are spirally formed by etching or plating on one side and the other side of each sheet element 10a, 10b with the intermediate portion 13 as a boundary. . The focusing drive coils 11 and 11 on one side and the other side are connected in series by a conductive pattern for connection 11a, and the tracking drive coils 12, 12 on one side and the other side are also connected in series by a conductive pattern for connection 12a. Was there. Further, the sheet bodies 10a and 10b are superposed and adhered to each other to form one sheet body 10, and terminals of a predetermined coil are connected by soldering or the like through the through holes 11b and 12b. The focusing drive coils 11 of the bodies 10a and 10b are connected in series, and similarly the tracking drive coils 12 of the sheet element bodies 10a and 10b are connected in series. These coil connections may be pattern-connected in parallel according to the required specifications of the DC resistance, etc., in order to obtain an appropriate impedance with the drive circuit. In this way, one sheet body 10 formed by stacking and adhering the two sheet body bodies 10a and 10b is fixed to the coil holding portion 20 along its outer shape as shown in FIG.

In this embodiment, when a drive current is passed through the focus drive coil 11 via the terminal 11c, thrust is generated by the drive current and the magnetic flux in the magnetic circuit including the focus magnet 6a. . This thrust is evenly generated in the focusing drive coils 11 and 11 symmetrically arranged in the shaft hole 7, and the shaft hole 7 of the objective lens holder 1 moves along the fixed axis so that the objective lens 2 moves in the optical axis direction. To move to the focusing operation. When a drive current is passed through the tracking drive coil 12 via the terminal 12c, thrust is generated by this drive current and the magnetic flux in the magnetic circuit including the tracking magnet 6b. This thrust is equally generated in the tracking drive coil 12 symmetrically arranged in the shaft hole 7, and the objective lens 2 moves in the direction orthogonal to the optical axis together with the objective lens holder 1 to perform the tracking operation.

In this case, according to this embodiment, particularly when the focus direction is controlled, the objective lens holder 1 and the balancer 3 are separated from each other in the vicinity of the objective lens holder 1 of the coil holding portions 20, 20. Since the cut portion 22 is provided so as to perform the focusing operation by moving the objective lens 2 along with the objective lens holder 1 in the optical axis direction, the cut portion 22 prevents vibration from the objective lens holder 1. It acts so as not to be cut and transmitted to the objective lens 2. That is, since the cut portion 22 and the balancer 3 are like a beam that is fixed at one end, the abnormal vibration that occurs is dynamically absorbed. As a result, abnormal vibration of the objective lens 2 can be suppressed, so that even if the ambient environment changes in temperature, a sufficient damping effect can be obtained regardless of this. FIG. 3 and FIG. 4 show the characteristics obtained in this example, in which the horizontal axis represents frequency and the vertical axis represents gain and phase. On the other hand, FIGS. 5 and 6 show conventional characteristics corresponding to FIGS. 3 and 4, respectively. As is clear from a comparison between FIGS. 3 and 4 and FIGS. 5 and 6, according to this embodiment, the peak of the higher resonance frequency can be particularly lowered, and the abnormal vibration of the objective lens 2 can be prevented. It shows that it can be suppressed. Moreover, since no adhesive material is used, the purpose can be achieved regardless of the temperature change of the surrounding environment. Furthermore, by not using an adhesive material such as double-sided adhesive tape, it will be possible to reduce costs.

[0020]

[Effect of device]

 As described above, according to the present invention, since the cut portion is provided in the coil holding portion of the objective lens holder including the balancer, the abnormal vibration of the objective lens can be suppressed and the surrounding vibration can be suppressed. It is possible to obtain a sufficient damping effect regardless of the temperature change of the environment.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an objective lens driving device of the present invention.

FIG. 2 is a plan view showing a sheet body on which a focus drive coil and a tracking drive coil used in this embodiment are formed.

FIG. 3 is a characteristic diagram showing a relationship between a frequency, a phase, and a gain, which is obtained in this embodiment.

FIG. 4 is a characteristic diagram showing the relationship between frequency, phase, and gain obtained in this example.

FIG. 5 is a characteristic diagram showing the relationship between frequency, phase, and gain obtained by a conventional example.

FIG. 6 is a characteristic diagram showing the relationship between frequency, phase, and gain obtained by a conventional example.

FIG. 7 is a cross-sectional view showing a conventional example.

FIG. 8 is a side view showing another conventional example.

FIG. 9 is a schematic view showing an objective lens holder on which an objective lens is mounted.

[Explanation of symbols]

 1 Objective Lens Holder 2 Objective Lens 3 Balancer (Magnetic Material) 6a Focusing Magnet 6b Tracking Magnet 10 Sheet Body 11 Focusing Drive Coil 12 Tracking Drive Coil 22 Cut Section

Claims (3)

[Scope of utility model registration request] 1. A balancer is attached to an objective lens holder on which an objective lens is mounted so that its attachment surface is parallel to the vibration resonance direction under the control drive of the objective lens.
In an objective lens driving device integrally provided with a coil holding portion for holding a sheet body on which a focus driving coil and a tracking driving coil are formed, a cut portion is provided in the coil holding portion of the objective lens holder including the balancer. An objective lens driving device characterized by: 2. The objective lens driving device according to claim 1, wherein the cut portion separates the objective lens holder and the balancer in the coil holding portion. 3. The objective lens driving device according to claim 1, wherein the cut portion is provided near the objective lens holder.