JPH0765391A - Objective lens driving device - Google Patents

Abstract

PURPOSE:To obtain an objective lens driving device in which a supporting mechanism part is prevented from being bent or twisted at the time of driving and an objective lens does not cause rolling or pitching. CONSTITUTION:This supporting mechanism part is molded as two blocks made of resin, and two blocks are connected through a leaf spring. Then, the center of gravity of a movable part is aligned with the center of a driving point acting on a displacing point in a tracking direction and a displacing point in a focusing direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device in an optical head for optically recording / reproducing information on / from an optical disk, and more particularly to a structure of a lens holder supporting / driving portion thereof.

[0002]

2. Description of the Related Art As is well known, an objective lens driving device used in an optical disk device drives an objective lens in a focusing direction with respect to surface wobbling of an optical disk,
The objective lens is driven in the tracking direction with respect to the eccentricity of the optical disc, and light is made to follow the signal surface of the optical disc surface.

FIG. 4 is a perspective view showing the structure of a conventional objective lens driving device, in which 1 is an objective lens and 2 is an objective lens.
Is a lens holder to which the objective lens 1 is attached, and 3 is a lens holder support drive unit (hereinafter, referred to as a lens holder support driving unit that supports the lens holder 2 in a state capable of being driven in a focusing direction (indicated by arrow Fo) and a tracking direction (indicated by arrow Tr).
It is simply called a support drive unit.

Further, FIG. 5A is a plan view showing the structure of the support drive unit 3 shown in FIG. 4, and FIG. 5B is a side view thereof. The support driving unit 3 is fitted with the lens holder 2 and is fixedly adhered thereto by adhesion, the parallel link unit 3b, and a pin hole 32 for fixing the support pin 9 to the actuator base.
A hinged rotary spring 30 having a hinge shaft in the vertical direction formed by thinning only that portion between the fitting portion 3a and the parallel link portion 3b.
Are provided at both ends of the parallel link portion 3b, and hinge portions 31 having a hinge shaft in the horizontal direction, which are formed by thinning only that portion, are provided respectively, and are integrally molded using a resin material. In such a structure, the lens holder 2 can be driven in the tracking direction by the hinge-type rotation spring 30, and can be driven in the focusing direction by the parallel link portion 3b having the hinge portion 31.

Further, the lens holder 2 has a coil attachment portion 4 extending in a wing shape to the left and right positions of the parallel link portion 3b, and a focus coil 5 and a track coil 6 are attached to the coil attachment portion 4, The drive magnet 7 and the yoke 8 are fixed on the actuator base 10 corresponding to the coils 5 and 6.

The conventional objective lens driving device is constructed as described above, and includes the focus coil 5 and the track coil 6.
The weight balance is adjusted so that the driving point by the lens holder 2, the fitting portion 3a, the hinge-type rotation spring 30, the parallel link 3b, and the centers of gravity of the coils 5 and 6 coincide with the movable portion. The rolling phenomenon in which the optical axis 1 tilts left and right and the pitching phenomenon in which the objective lens vibrates in the focusing direction are suppressed.

[0007]

Although the conventional objective lens driving device is constructed as described above, there is a problem that both the pitching phenomenon and the rolling phenomenon cannot be sufficiently suppressed.

That is, the conventional objective lens driving device is
Although the driving point of the coil is made to coincide with the position of the center of gravity of the movable portion, vibration causes a thin uniform plate-like parallel link portion 3b to generate a twist and a twist, which causes the objective lens to roll, and The vibration causes a pitching phenomenon in which the lens holder is tilted in the vertical direction about the hinged rotation spring 30, which deteriorates the performance. Also,
The hinge-type rotation spring 30, which is the actual movable position in the tracking direction, is not located at the center of gravity of the movable portion, so that the driving efficiency is poor, and it is easy for vibrations to occur, such as screwing and twisting. Further, since the hinge type rotation spring 30 is located at a position apart from the parallel link portion 3b, it is difficult to reduce the size of the device due to a problem in component structure.

In addition, it is assumed that the movable position, that is, FIGS.
Speaking of the device shown in FIG. 1, even if the hinge type rotating spring 30 is arranged so that the position thereof coincides with the driving point of the coil, the conventional device is integrally molded with resin up to the hinge part, and therefore the rigidity of the hinge part is increased. Becomes weaker, resonates at a low frequency during driving, and pitching and rolling phenomena easily occur.

FIG. 6A is a side view showing a vibration analysis simulation showing a rolling state in a structure of an objective lens driving device in which a hinge portion 60 serving as a driving point in a tracking direction is matched with a driving point of a coil. FIG. 7B is a perspective view of the same, and FIG. 7 is a side view showing a vibration analysis simulation showing the state of pitching vibration. From these figures, the rolling and pitching states of the conventional device can be seen.

[0011]

An objective lens driving device according to the present invention has at least one first displacement point for driving an objective lens made of a resin material and formed of a notch hinge in a focusing direction. A first frame having the same, a second frame having at least one first displacement point made of a resin material and formed by a notch hinge, and between the first frame and the second frame. It is characterized in that a supporting drive unit is configured with a leaf spring provided, and the leaf spring is used as a second displacement point for driving the objective lens in the tracking direction.

Further, the first frame has four axes of up, down, left, and right substantially parallel to the actuator base, and each axis is provided with the first displacement point, and the end portion has two left and right upper axes and a lower side. The left and right two axes are integrated, and the second frame has four axes, that is, upper, lower, left, and right substantially parallel to the actuator base, and the first displacement point is provided on each axis, and the end portion is on the upper side. The left and right two shafts and the lower left and right two shafts are integrated respectively, and the leaf spring is provided between the upper end of the first frame and the upper end of the second frame. A so-called biaxial support drive unit in which the leaf spring is provided between the lower end of the first frame and the lower end of the second frame is also configured. On the upper side and the lower side, the diagonal of each of the four first displacement points The leaf spring being the second displacement point to the intersection of the above is characterized in that a support mechanism located.

Further, a balancer is attached to the lens holder, and the position of the leaf spring and the position of the center of gravity of the entire movable portion centered on the lens holder are made to coincide with each other.

[0014]

In the objective lens driving device of the present invention, with the above-mentioned structure, the supporting mechanism can be formed without using a wide leaf spring or a hinge, and the driving center in the focusing direction and the driving center in the tracking direction can be formed. And the position of the center of gravity of the movable portion can be made to coincide with each other, and it is possible to prevent the occurrence of a twist or twist of the support mechanism portion during driving. As a prior art related to the invention of the present application, Japanese Patent Application Laid-Open No. 2-3, in which the support mechanism section is made of an elastic material to prevent the inclination of the optical axis.
No. 7534 “Objective lens drive mechanism”, which has a structure in which the center of gravity of the movable portion and the drive center are made to coincide with each other.
No. 740 “Objective Lens Actuator”.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of an objective lens driving device of the present invention, in which 1 is an objective lens and 2 is an objective lens.
Is a lens holder to which the objective lens 1 is attached, and 20 is a support drive unit in the present embodiment. Further, the lens holder 2 has a coil attachment portion 4 extending in a wing shape to the left and right side surfaces of the support drive portion 20, and a focus coil 5 and a track coil 6 are attached to the coil attachment portion 4, and these coils 5, 6 are provided. Accordingly, the drive magnet 7 and the yoke 8 are fixed on the actuator base 10. Further, the lens holder 2 has a structure provided with a balancer 11 for adjusting the center of gravity of the movable portion.

2A and 2B are views for explaining the structure of the supporting and driving section 20 shown in FIG. 1. FIG. 2A is a side view and FIG. 2B is a sectional view taken along the line HH 'in FIG. FIG. 6C is a diagram showing a positional relationship between a focusing hinge and a tracking leaf spring of Section 4 described later. As shown in FIG. 2, the support driving unit 20 of the present embodiment has four shafts extending vertically and horizontally from the fitting unit 201 that is fitted and fixed to the lens holder 2, and each of the shafts is used for focusing. The one-side cutout hinge portion 31 is provided, and a resin-made first frame 21 in which the upper two shafts and the lower two shafts are integrated at the tip end portion, and the first frame 21 Four shafts are vertically and horizontally extended from a base end portion 202 fixed to the actuator base 10 by the support pins 9 so as to face each other, and one-side cutout hinge portions 31 are provided on the shafts, respectively. A second frame 22 made of resin in which a single shaft and two lower shafts are integrated; a top and bottom end portion of the first frame 21 and a top and bottom end portion of the second frame 22, respectively. 2 leaf springs 23 for tracking to connect It is configured. Therefore, the support shaft is composed of the two leaf springs 23, and the support movable portion 20 of the present invention is a so-called biaxial support movable portion.

Further, as shown in FIG. 2C, for example, the tracking leaf spring 2 is located at an intersection point on a diagonal line of the focusing hinge 31 of the upper section 4 (the same is true of the lower section).
3 is positioned so that the drive center in the focusing direction and the drive center in the tracking direction coincide with each other when viewed from the whole of the support drive section 20. The balancer 11 is provided so that the above-described drive center is located at the center of gravity of the entire movable portion (actuator).

That is, in the present invention, first of all, the supporting and driving section 20 is composed of two resin frames of the upper and lower two-stage structure (first
Frame, second frame), and by connecting these two frames with a leaf spring 23 made of a different material such as a metal leaf spring, vibration is prevented from occurring and rolling phenomenon and pitching phenomenon are less likely to occur. With the structure. Also,
The leaf springs 23 are located at the diagonal intersections of the four focus hinges 31 provided on the two frames. This improves the driving efficiency of focusing and tracking, and prevents the screwing and twisting during driving. However, it has a structure that suppresses the occurrence of vibration. Further, the balancer 11 is attached to the lens holder 2 to adjust the weight balance, so that the position of the center of gravity of the entire movable portion coincides with the intersection, thereby preventing the screwing and twisting at the time of driving and preventing the occurrence of vibration. The rolling structure and the pitching phenomenon are less likely to occur.

FIG. 3A is a plan view showing a vibration analysis simulation when the objective lens driving device in this embodiment is driven in the tracking direction, and FIG. 3B is a vibration analysis when driven in the focusing direction. FIG. 8 is a side view showing a simulation, as is clear from comparison with FIGS. 6 and 7 in the case where the leaf spring 23 portion has a resin hinge structure, it is possible to prevent twisting and twisting,
It can be seen that neither the pitching phenomenon has occurred.

[0020]

As described above, the objective lens driving device of the present invention has a structure in which the resin supporting and driving portion is divided into two parts, and the space between them is connected by the tracking leaf spring.
It is possible to prevent the phenomenon of twisting and twisting that have occurred in the conventional wide leaf spring and wide hinge, and to prevent the rolling phenomenon and the pitching phenomenon of the objective lens. In particular, it is possible to remarkably prevent the pitching phenomenon that occurs due to the resonance at low frequency due to the weak rigidity of the hinge portion in the conventional device.

Further, the objective lens driving device of the present invention has four
Since the leaf springs for tracking are provided at the intersections on the diagonals of the focusing hinges of the nodes, it is possible to perform focusing drive, which is the drive in the focusing direction against the surface deflection of the optical disc in the optical disc device, and driving in the tracking direction with respect to the eccentricity of the optical disc. It is possible to eliminate unnecessary driving during a certain tracking driving and to drive efficiently.

Further, the objective lens driving device of the present invention is
By using a resin-made integrally molded biaxial hinge, the number of parts can be reduced, and the man-hours required for assembling the device can be reduced.
There is an effect that the device can be downsized and the like.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining an embodiment of the structure of the support drive unit of the present invention.

FIG. 3 is a diagram showing a vibration analysis simulation in the present embodiment.

FIG. 4 is a perspective view showing a configuration of a conventional objective lens driving device.

FIG. 5 is a diagram for explaining an example of a support drive unit in a conventional device.

FIG. 6 is a diagram showing a vibration analysis simulation for explaining a problem of the conventional device.

FIG. 7 is a diagram showing a vibration analysis simulation for explaining a problem of the conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Lens holder 4 Coil mounting part 5 Focus coil 6 Track coil 7 Magnet 8 Yoke 9 Support pin 10 Actuator base 11 Balancer 20 Support drive part 21 First frame 22 Second frame 23 Leaf spring 31 Hinge part

Claims (3)

[Claims] 1. A first device, which is provided between a lens holder having an objective lens mounted thereon and an actuator base, supports the lens holder in the air above the actuator base, and drives the objective lens in a focusing direction.
An objective lens driving device having a supporting and driving unit having a displacement point of 1 and a second displacement point for driving the objective lens in the tracking direction, the first lens being formed of a resin material and formed by a notch hinge. A first frame having at least one or more displacement points, a second frame formed of a resin material and having at least one or more first displacement points formed by a notch hinge, and the first frame And an leaf spring provided between the second frame, and a support driving unit having the leaf spring as the second displacement point. 2. The first frame has four axes of up, down, left, and right substantially parallel to the actuator base, and each axis is provided with the first displacement point formed by the notch hinge, and an end portion is The upper left and right two shafts and the lower left and right two shafts are integrated respectively, and the second frame has four shafts vertically and horizontally substantially parallel to the actuator base, and each shaft is formed by the cutout hinge. The first displacement point is provided at each end, and the upper left and right two axes and the lower left and right two axes are integrated, and the upper end of the first frame and the upper end of the second frame are integrated. The leaf spring is provided between the lower end of the first frame and the lower end of the second frame, which is a so-called leaf spring. Forming a biaxial support drive section, and above the biaxial support drive section And a support mechanism section in which the leaf springs, which are the second displacement points, are located at diagonal intersections of the four first displacement points, respectively. Item 7. The objective lens driving device described in the item. 3. A balancer is attached to the lens holder so that the position of the leaf spring and the position of the center of gravity of the entire movable portion centered on the lens holder are aligned with each other. Item 7. The objective lens driving device described in the item.