JP2000147350A - Lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the miniaturization of a device, to improve the assemblability and to stabilize the quality by forming a notched hole communicating between the inside and outside of a cylindrical lens barrel where a movable lens part is arranged, and attaching a yoke constituting a magnetic circuit to the lens barrel from the outside so that the yoke may be partly positioned inside the lens barrel and fitting a driving coil to a part of the yoke so that it may be made freely slidable. SOLUTION: As for the lens driving device, the driving coil 14 attached to each movable lens part 4 and 6 of the camera is moved in the optical axis direction X-X by the magnetic circuit 16 constituted of a magnet 18 and the yoke 17. The notched hole 2a communicating between the inside and the outside is formed on the cylindrical lens barrel 2 in which the movable lens part is arranged, then, the yoke constituting the magnetic circuit is attached to the lens barrel from the outside so that the yoke may be partly positioned inside the lens barrel, then, the driving coil is arranged so that it may be freely slidably fitted to a part of the yoke from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel lens driving device. More specifically, the present invention relates to a technology for miniaturizing, improving assemblability, and stabilizing quality in a lens driving device that moves a driving coil provided on a movable lens portion of a camera in a direction of an optical axis by a magnetic circuit including a magnet and a yoke. .

[0002]

2. Description of the Related Art There is a camera lens driving device using a so-called linear actuator which drives a coil linearly by a magnetic circuit composed of a magnet and a yoke.

In the above-described linear actuator, for example, as shown in FIG. 6, a magnetic circuit is constituted by a yoke a having a U-shape and a magnet b fixed thereto, and a part a 'of the yoke a and a magnet b A drive coil c is disposed in a gap between the two, and the drive coil c is fixed to a movable lens portion of a camera (not shown).

When the drive coil c is energized, the drive coil c is driven in the direction in which the yoke a extends, and the movable lens portion to which the drive coil c is fixed is moved in the direction in which the yoke a extends. Will be.

[0005]

In the above-mentioned conventional magnetic circuit, as a procedure for assembling, first, the yoke a and the magnet b are arranged at the back of the lens barrel, so that it is difficult to fix the yoke a and the magnet b. However, there is a problem that it is difficult to fix a metal part, for example, a screw, a metal shaft, or the like.

Further, since a U-shaped yoke a is used,
There was also a problem that its production was difficult.

It is an object of the present invention to reduce the size, improve the assemblability, and stabilize the quality.

[0008]

In order to solve the above-mentioned problems, a lens driving device according to the present invention is provided with a notch hole for communicating the inside and outside with a cylindrical lens barrel in which a movable lens portion is disposed. A yoke constituting the magnetic circuit is externally attached to the lens barrel so that a part of the yoke is located in the lens barrel, and the drive coil is slidably fitted to a part of the yoke. It is arranged in.

Therefore, in the lens driving device of the present invention, the yoke can be easily attached to the lens barrel, so that the assemblability is improved, the size is reduced, and the quality is stabilized.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings.

The lens barrel 1 includes a lens barrel 2 having a long cylindrical shape in the front-rear direction, and required components and members are supported by the lens barrel 2. The lens barrel 2 has a notch hole 2a which is long in the front-rear direction on the outer peripheral wall.

The imaging lens of the lens barrel 1 has a four-group configuration. The first lens group 3 is a fixed lens group fixed to the front end of the lens barrel 2, and the second lens group 4 is the first lens group. A movable lens group that is disposed immediately behind the lens group 3 and is movable in the optical axis direction, that is, the arrow XX direction in the figure, and a fixed lens in which the third lens group 5 is disposed behind the second lens group 4. The lens group and the fourth lens group 6 correspond to the third lens group 5 and the image sensor 7.
The second lens group 4 is a zoom lens that performs zooming, and the fourth lens group 6 is a focus lens that performs focusing. ing. An iris device 8 is provided immediately in front of the third lens group 5.

Each of the movable lens groups 4 and 6 has its constituent lens held by a lens holding frame 9.

The lens holding frame 9 has a substantially ring-shaped frame portion 10 at the center, and the lenses constituting the lens group 4 or 6 are held and fixed to the frame portion 10.

A guided portion 11 protrudes from a part of a side edge of the lens holding frame 9, and the guided portion 11 is formed with a U-shaped notch 11a.

The guided portion 11 of the lens holding frame 9
A guided cylinder 12 whose axial direction extends in the optical axis direction X-X is formed integrally with a portion substantially opposite to the portion where is formed.

Guide shafts 2b and 2c extending in the optical axis direction XX are provided in the lens barrel 2. A notch 11a of the lens holding frame 9 is slidably engaged with the guide shaft 2b.
The guided cylinder 12 of the lens holding frame 9 is slidably fitted on the guide shaft 2c. Thereby, the lens holding frame 9 is guided in the optical axis direction XX.

At the other end of the lens holding frame 9, a flat rectangular tubular bobbin 13 having a cross-sectional shape is integrally formed, and a coil (not shown) is wound around the bobbin 13 to drive the coil. 14 are formed. The bobbin 1
3 also extends in the optical axis direction XX.

A magnetic circuit 16 constituting a linear actuator 15 together with the drive coil 14 is provided in the lens barrel 2.
Is fixed. The magnetic circuit 16 includes a yoke 17 and a magnet 18. The magnetic circuit 16 includes the linear actuators 15 of the second lens group 4 and the fourth lens group 6,
15 are common.

The yoke 17 is an inner yoke 1 made of a magnetic material.
9 and the outer yoke 20. The inner yoke 19 includes a main part 21 that is long in the front-rear direction, that is, the optical axis direction XX, and the mounting piece 2 bent at the rear end of the main part 21.
2 are integrally formed. Rectangular connecting holes 21a, 21a are formed at both front and rear ends of the main portion 21, and a mounting hole 22a and a mounting notch 22b are formed in the mounting piece 22. The inner yoke 19 is a screw 22 that is inserted into the mounting hole 22a and the mounting notch 22b in a direction in which the main part 21 extends along the optical axis direction XX in the lens barrel 2.
It is fixed to the lens barrel 2 by c.

The outer yoke 20 is in the front-rear direction,
The main portion 23, which is long in the optical axis direction XX, and connecting pieces 24, 24 protruding in the same direction from both front and rear ends of the main portion 23 are integrally formed. Joint pieces 24a, 24a are protruded. In addition, mounting pieces 25, 25 are protruded from a portion of the main portion 23 near the front end of one side edge and a portion near the rear end of the other side edge.
25 has mounting holes 25a, 25a.

The magnet 18 is fixed to the inner surface of the main portion 23 of the outer yoke 20, that is, the surface on the side from which the connecting pieces 24 project.

As described above, the drive coils 14 of the second lens group 2 and the drive coils 14 of the fourth lens group 6 are slidably mounted on the main portion 21 of the inner yoke 19 fixed in the lens barrel 2. Be fitted. Then, the connecting pieces 24, 2 of the outer yoke 20
4 is inserted into the lens barrel 2 through the notch hole 2a, and the fitting pieces 24a, 24a thereof are connected to the connection holes 21a, 2a of the inner yoke 19, respectively.
1a in a press-fit manner, and in that state, the mounting pieces 25, 25
Are screwed into the lens barrel 2, whereby the outer yoke 20 is connected to the lens barrel 2.
The yoke 17 is formed by connecting the inner yoke 19 and the outer yoke 20 to the magnetic circuit 1 from outside.
6 are formed, and the linear actuators 15, 1
5 are configured. A flexible printed circuit board 25 is disposed in the lens barrel 2 and the linear actuator 1
Electric current is supplied to the drive coils 14 and 14 of the flexible printed circuit board 25.

When the driving current is supplied to the driving coils 14, 14, the lens holding frames 9, 9 are moved in the optical axis direction XX, and the second lens group 4 or the fourth lens group 6 is moved. Moving in the optical axis direction XX, zooming or focusing is performed.

In the above-described lens driving device, the yoke 17 is assembled to the lens barrel 2 with a part thereof being inserted into the lens barrel 2 through the notch hole 2a.
6 can be easily attached to the lens barrel 2.

The yoke 17 comprises an inner yoke 19 and an outer yoke 20, and each of the yokes 19, 20 has a small bent piece (a mounting piece 22 and connecting pieces 24, 24) at its end.
Therefore, compared to a conventional yoke formed in a deep U-shape, it can be formed easily and the dimensional accuracy can be improved. .

Further, the outer yoke 20 and the inner yoke 19
Since the drive coils 14 and 14 can be slidably fitted to the inner yoke 19 before the yoke 17 is completed by combining the drive coils, the assemblability is improved and the gap can be easily adjusted. The quality can be stabilized in combination with the improvement of the dimensional accuracy.

Further, as described above, the magnetic circuit 1
By making 6 common to the linear actuators 15 and 15 of the two movable lens portions 4 and 6, it contributes to downsizing. It is needless to say that the magnetic circuit may be provided separately for each of the two linear actuators. Alternatively, it may be common to the linear actuators of three or more movable lens units.

FIGS. 4 and 5 show a modification 16A of the magnetic circuit.

The magnetic circuit 16A is provided with two apparent magnetic circuits. Therefore, this magnetic circuit 1
6A, an intermediate yoke 27 is prepared, and the intermediate yoke 27 is bridged between an intermediate portion of the inner yoke 19 and an intermediate portion of the outer yoke 20. The intermediate yoke 27 is formed of a magnetic material and has a plate-like shape with its front surface facing forward and backward, and fitting pieces 27a, 27a protrude from upper and lower ends thereof.
In the middle of the main part 21 of the inner yoke 19, the connecting hole 2 is formed.
1b, and a connection hole 23a is formed at an intermediate portion of the main portion 23 of the outer yoke 20.
7 are press-fitted into the connection holes 21b of the inner yoke 19 and the connection holes 23a of the outer yoke 20, respectively.
And an intermediate portion of the main portion 23 of the outer yoke 20 are connected by an intermediate yoke 27.

In the inner surface of the main portion 23 of the outer yoke 20, magnets are respectively provided on a portion between the intermediate yoke 27 and the front connecting piece 24 and a portion between the intermediate yoke 27 and the rear connecting piece 24. 18A, 18A are fixed.

In the magnetic circuit 16A, two magnetic paths are formed before and after as shown by arrows in FIG. 5, and thus two magnetic circuits are apparently formed.

In the linear actuator, there is a problem that as the length increases, the thickness of the yoke in the magnetic circuit increases. However, as in the magnetic circuit 16A, by forming two magnetic circuits in appearance, Thus, the thickness of the yoke can be kept thin. If there are three or more objects to be driven, two or more intermediate yokes may be provided to form an apparently three or more magnetic circuit.

It should be noted that the shapes and structures of the respective parts shown in the above-described embodiments are merely examples of the specific embodiments to be carried out when carrying out the present invention, and the technical scope of the present invention is not limited thereto. Should not be interpreted restrictively.

[0035]

As is apparent from the above description, in the lens driving apparatus of the present invention, the driving coil provided on the movable lens portion of the camera is moved in the optical axis direction by a magnetic circuit composed of a magnet and a yoke. A lens driving device, wherein a cutout hole is formed for communicating the inside and the outside with a cylindrical lens barrel in which the movable lens portion is disposed, and a yoke constituting the magnetic circuit is partially mirrored. The drive coil is externally attached to the lens barrel so as to be located in the cylinder, and the drive coil is arranged so as to be slidably fitted to a part of the yoke.

Therefore, in the lens driving device of the present invention, the yoke can be easily attached to the lens barrel, so that the assemblability is improved, the size is reduced, and the quality is stabilized.

According to the second aspect of the invention, since two or more movable lens portions are provided and the yoke is provided in common with the two or more movable lens portions, the structure is simplified. And further downsizing can be achieved.

According to the third and fourth aspects of the invention, the yoke is located inside and the inner yoke to which the drive coil is fitted, and the outer yoke is located outside and fixed to the inner yoke. Since the yoke is formed, the yoke can be easily formed and assembled, and the dimensional accuracy can be improved. As a result, the assemblability can be improved and the quality can be stabilized.

According to the fifth aspect of the present invention, the inner yoke and the outer yoke are connected by one or more intermediate yokes to form an area corresponding to two or more movable lenses in the lens driving direction. Since the magnetic circuit is divided and the number of magnetic circuits corresponding to the number of movable lenses is apparently formed, the thickness of the yoke is kept thin while the yoke is provided in common for the two or more movable lens portions. Can be.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the lens driving device of the present invention together with FIGS. 2 and 3, which is a schematic longitudinal sectional view of a lens barrel.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged exploded perspective view of a yoke.

FIG. 4 shows a modification of the magnetic circuit together with FIG. 5, and FIG. 4 is an enlarged exploded perspective view.

FIG. 5 is an enlarged side view.

FIG. 6 is an exploded perspective view showing a conventional magnetic circuit.

[Explanation of symbols]

Reference numeral 2 denotes a lens barrel, 2a denotes a cutout hole, 4 denotes a second lens group (movable lens portion), 6 denotes a fourth lens group (movable lens portion), 14 denotes a drive coil, 16 denotes a magnetic circuit, 17 denotes a yoke, and 18 denotes a lens. Magnet, 19 ... inner yoke, 20 ... outer yoke, 21 ...
Main part (part of yoke), XX: optical axis direction, 16A: magnetic circuit, 18A: magnet, 27: intermediate yoke

Claims (5)

[Claims] 1. A lens driving device for moving a drive coil provided on a movable lens portion of a camera in a direction of an optical axis by a magnetic circuit including a magnet and a yoke, wherein the movable lens portion is disposed inside. Forming a cutout hole for communicating the inside and the outside of the cylindrical lens barrel; attaching a yoke constituting the magnetic circuit to the lens barrel from outside so that a part of the yoke is located in the lens barrel; A lens driving device, wherein the lens driving device is slidably fitted to a part of the yoke. 2. The lens driving device according to claim 1, wherein the lens driving device has two or more movable lens portions, and the yoke is provided in common with the two or more movable lens portions. 3. The yoke according to claim 1, wherein the yoke comprises an inner yoke located inside and to which the drive coil is fitted, and an outer yoke located outside and fixing the inner yoke. Lens driving device. 4. The yoke according to claim 2, wherein the yoke comprises an inner yoke located inside and to which the drive coil is fitted, and an outer yoke located outside and fixing the inner yoke. Lens driving device. 5. An inner yoke and an outer yoke are connected by one or more intermediate yokes to divide the movable yoke into regions corresponding to two or more movable lenses in the lens driving direction. The lens driving device according to claim 4, wherein a corresponding number of magnetic circuits are formed.