JP2004280031A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an accurate lens driving device which is made small in size and light in weight, and whose errors made when a lens is linearly moved are reduced. <P>SOLUTION: In the lens driving device 1 equipped with a U-shaped cylindrical yoke 2, a magnet 4 mounted on the inner surface of the external wall 2b of the yoke 2, a carrier 5 equipped with a lens 3 at a center position, a coil 6 attached to the carrier 5, a base 7 to which the yoke 2 is attached, a frame 8 supporting the base 7 and two springs 9a and 9b supporting the carrier 5, the two same springs 9a and 9b are arranged to support the carrier 5 while holding it from above and below, and made to function as a feed path to the coil 6 respectively, then the moving amount of the lens 3 attached to the carrier 5 is controlled by the balance of a current value applied to the coil 6 with the restoring force of the two springs 9a and 9b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an autofocus lens driving device used for a portable small camera.
[0002]
[Prior art]
As this type of lens driving device, a device using a combination of a stepping motor and a feed screw transmission mechanism is known, and this lens driving device is shown in FIG.
As shown in FIG. 4, the lens driving device 100 transmits the rotating shaft of the stepping motor 101 to the feed screw 103 via the gear 102 to convert the rotational motion into a linear motion. A lens 105 is fixed on a nut 104 guided and driven on a feed screw 103. Therefore, the linear movement amount of the lens 105 is determined according to the rotation angle of the stepping motor 101.
[0003]
[Problems to be solved by the invention]
However, in the above-described technology, since a complicated transmission mechanism such as the stepping motor 101, the gear 102, the feed screw 103, and the nut 104 is required, the device becomes large, and an error occurs in the movement amount of the lens 105. There are issues.
[0004]
Accordingly, it is an object of the present invention to provide a lens driving device which is small and lightweight, has a small error when the lens is linearly moved, and has high accuracy.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, a U-shaped cylindrical yoke, a magnet mounted on the inner surface of an outer wall of the yoke, a carrier having a lens at a central position, a coil mounted on the carrier, and a yoke are mounted. In a lens driving device including a base, a frame supporting the base, and two springs supporting the carrier, the two springs are arranged such that the same product supports the carrier from above and below, and Function as a power supply path to the coil,
The amount of movement of the lens mounted on the carrier is controlled by balancing the current value applied to the coil and the restoring force of the two springs.
[0006]
According to the first aspect of the present invention, since the same two springs are arranged so as to support the carrier vertically, the axial displacement of the lens can be suppressed small, and the lens can be accurately moved. Can be.
[0007]
According to a second aspect of the present invention, in the first aspect of the present invention, the coil is subjected to pressure forming after winding.
[0008]
According to the second aspect of the present invention, the same operation and effect as those of the first aspect of the invention can be obtained, and the coil is formed by pressing after winding, so that the uniformity and the assembling property of the coil can be improved. it can.
[0009]
According to a third aspect of the present invention, in the first or second aspect of the present invention, the carrier strikes the base at the lowest position and strikes the inner yoke at the highest position.
[0010]
According to the third aspect of the invention, the same operation and effect as those of the first or second aspect of the invention can be obtained, and the carrier can be prevented from coming off because the carrier has a vertical abutting mechanism.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a lens driving device according to the present invention, FIG. 2 is an exploded perspective view of the lens driving device of FIG. 1, and FIG. 3 is a cross-section showing the operation of the lens driving device of FIG. FIG.
[0012]
The lens driving device 1 includes the Y-shaped cylindrical yoke 2, a magnet 4 attached to an outer wall of the yoke 2, a carrier 5 having a lens 3 at a central position, a coil 6 mounted on the carrier 5, and the yoke 2. The vehicle includes a base 7 to be mounted, a frame 8 supporting the base 7, two springs 9a and 9b for vertically supporting the carrier 5, and two caps 10a and 10b for covering these up and down. The two springs 9a and 9b are the same product, support the carrier 5 from above and below in the same positional relationship, and function as a power supply path to the coil 6. By applying a current to the coil 6, the carrier 5 moves upward. In this specification, the terms above and below are used as appropriate, but refer to the upper and lower parts in FIG. 1, and the upper part indicates the positional relationship from the camera to the subject.
[0013]
The yoke 2 is a magnetic material such as soft iron, has a U-shaped cylindrical shape with a closed upper surface, and has a cylindrical inner wall 2a and an outer wall 2b. A ring-shaped magnet 4 is attached (adhered) to the inner surface of the U-shaped outer wall 2b.
[0014]
The carrier 5 is a molded product made of a synthetic resin or the like having a cylindrical structure having a bottom portion, supports a lens at a central position, and has a coil 6 formed in advance adhered and mounted on the outside of the bottom surface. The yoke 2 is fitted into the inner peripheral portion of the base 7 of the resin molded product on the rectangular shape, and the yoke 2 is fitted therein.
[0015]
The lower spring 9b is fixed between the bottom of the carrier 5 and the base 7, and the upper spring 9a is fixed between the uppermost part of the carrier 5 and the frame 8. Each of the springs 9a and 9b has its outermost peripheral portion fixed by being sandwiched between the frame 8 and the base 7, and the notch groove portion at every 120 ° of the inner peripheral portion fits into the carrier 5 and is fixed by heat caulking or the like. .
The spring 9b and the base 7 and the spring 9a and the frame 8 are fixed by bonding and heat caulking, etc. Further, the cap 10b is mounted on the bottom of the base 7, and the cap 10a is mounted on the upper part of the frame 8, and the spring 9b is mounted on the base. Between the frame 7 and the cap 10b, a spring 9a is sandwiched and fixed between the frame 8 and the cap 10a.
[0016]
One lead wire of the coil 6 extends upward through a groove provided in the inner peripheral surface of the carrier 5 and is soldered to the spring 9a. The other lead wire extends downward through a groove provided in the bottom surface of the carrier 5 and is soldered to the spring 9b.
[0017]
The springs 9a and 9b are leaf springs made of metal such as phosphor bronze, and have a spring property and also function as a power supply path to the coil 6. One of the outer peripheral portions of the springs 9a and 9b is projected outward to function as a power supply terminal.
[0018]
The cylindrical magnet 4 is magnetized in the radial (radial) direction, forms a magnetic path through the inner wall 2a, the upper surface, and the outer wall 2b of the U-shaped yoke 2, and forms a gap between the magnet 4 and the inner wall 2a. , A coil 6 is arranged.
[0019]
Since the springs 9a and 9b have the same shape and are mounted in the same positional relationship as shown in FIGS. 1 and 2, the displacement of the shaft when the carrier 5 moves upward can be suppressed. Since the coil 6 is manufactured by pressure molding after winding, the accuracy of the finished outer diameter is improved, and the coil 6 can be easily arranged in a predetermined narrow gap. The carrier 5 hits the base 7 at the lowest position and hits the yoke 2 at the highest position. Therefore, the carrier 5 is provided with a hitting mechanism in the vertical direction, and is prevented from falling off.
[0020]
FIG. 3 is a cross-sectional view when a current is applied to the coil 6 to move the carrier 5 having the lens 3 for autofocus upward. When power is applied to the power supply terminals of the springs 9a and 9b, current flows through the coil 6 and an upward electromagnetic force acts on the carrier 5. On the other hand, the restoring force of the two connected springs 9a and 9b acts on the carrier 5 downward. Therefore, the upward moving distance of the carrier 5 is a position where the electromagnetic force and the restoring force are balanced. Thus, the amount of movement of the carrier 5 can be determined by the amount of current applied to the coil 6.
[0021]
Since the upper spring 9a supports the upper surface of the carrier 5 and the lower spring 9b supports the lower surface of the carrier 5, the restoring force acts uniformly downward on the upper and lower surfaces of the carrier 5, and the axis of the lens 3 Deviation can be kept small.
[0022]
Therefore, when the carrier 5 is moved upward, a guide by a rib or the like is not required and is not used. Since there is no sliding friction due to the guide, the moving amount of the carrier 5 is purely governed by the balance between the electromagnetic force and the restoring force, and the smooth and accurate movement of the lens 3 is realized. This achieves autofocus with less lens blur.
[0023]
Although the magnet 4 has been described as having a cylindrical shape, the present invention is not limited to this. The magnet 4 may be divided into three or four parts and magnetized in the radial direction, and the magnet may be adhered to the inner surface of the outer wall 2 b of the yoke 2.
[0024]
【The invention's effect】
According to the first aspect of the present invention, since two identical springs support the carrier vertically, the lens can be moved with less axial displacement.
[0025]
According to the second aspect of the invention, the same effects as those of the first aspect of the invention can be obtained, and a small and uniform coil can be mass-produced.
[0026]
According to the third aspect of the invention, the same effects as those of the first and second aspects of the invention can be obtained, and the carrier can be prevented from falling off.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a lens driving device according to the present invention.
FIG. 2 is an exploded perspective view of the lens driving device of FIG.
FIG. 3 is a sectional view showing an operation of the lens driving device of FIG. 1;
FIG. 4 is a perspective view showing a conventional lens driving device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Yoke 3 Lens 4 Magnet 5 Carrier 6 Coil 7 Base 8 Frame 9a Upper spring 9b Lower spring 10a, 10b Cap

Claims (3)

A U-shaped cylindrical yoke, a magnet attached to the inner surface of the outer wall of the yoke, a carrier having a lens at a central position, a coil mounted on the carrier, a base on which the yoke is mounted, and a frame supporting the base, A lens drive device comprising two springs supporting a carrier,
The two springs are arranged so that the same product sandwiches and supports the carrier from above and below, and each functions as a power supply path to the coil,
A lens driving device for controlling a moving amount of a lens mounted on a carrier by balancing a current value applied to a coil and a restoring force of two springs. The lens drive device according to claim 1, wherein the coil is formed by pressure after winding. The lens driving device according to claim 1, wherein the carrier abuts on the base at a lowermost position, and abuts on an inner yoke at an uppermost position.

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