JP4324368B2 - Lens drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens driving device that is used in a portable small camera and zooms an object.
[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. 5, the lens driving device 100 transmits the shaft of the rotating 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 the feed screw 103. Therefore, the linear position 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, the above-described technique requires complicated transmission mechanisms such as the stepping motor 101, the gear 102, the feed screw 103, and the nut 104, so that the apparatus becomes large and the accuracy of the position of the lens 105 is poor. There is.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a lens driving device that is small and light and has good positional accuracy even when the lens is linearly moved.
[0005]
[Means for Solving the Problems]
The invention according to claim 1 is attached to the front lens, the front lens frame that supports the front lens, the front support that supports the front lens frame, the front coil that is attached to the front support, and the front support. A front spring, a rear lens, a rear support for supporting the rear lens, a rear coil attached to the rear support, a rear spring attached to the rear support, a magnet, a magnet support, an inner wall and an outer wall; The magnet support is provided between the inner wall and the outer wall of the yoke, and a magnet is arranged with a gap between each wall. , magnet Yes magnetized in the radial direction, the forward coil, arranged wound around the outer gap in the circumferential direction between the magnet and the yoke outer wall, the rear coil, magnet and yaw Wound inside the gap in the circumferential direction between the inner wall and disposed to impart longitudinal direction of the driving force to the front lens by applying a current to the forward coil, position balance the front lens and the elastic force of the front spring A lens driving device that applies a current to the rear coil to apply a driving force in the front-rear direction to the rear lens, and moves the rear lens to a position that balances the elastic force of the rear spring. And the rear spring each have a substantially semicircular inner peripheral side portion and an outer peripheral side portion, and the inner peripheral side portion and the outer peripheral side portion are connected at one end in the circumferential direction, and the circumferential direction of the inner peripheral side portion Two leaf springs having an inner end that is the other end and an outer end that is the other end in the circumferential direction of the outer peripheral side are combined into a substantially ring shape, and each leaf spring is flat before assembly. Yes, and stretched to create a step between the inner and outer ends when assembled and elastically deformed The front end of the front spring is fixed to the front end of the front support, the inner end is fixed to the front end of the magnet support, and the rear end of the rear spring is the rear end of the magnet support. And the outer end portion is fixed to the rear end of the rear support.
[0006]
In the first aspect of the present invention, magnets magnetized in the radial direction with a gap therebetween are arranged between the inner wall and the outer wall of the yoke, and the front coil and the rear coil corresponding to each gap are arranged in the circumferential direction of the yoke. Since it is wound around and arranged in the yoke, the structure of the apparatus can be made small. Furthermore, since moving the elastic force and are balanced position in the longitudinal direction of the driving force and the two spring of each lens produced depending on the current applied to the front coil and the rear coil, only the amount of current flowing through the respective coils, The amount of movement can be determined. As a result, the structure of the apparatus can be further reduced. Compared with the prior art shown in FIG. 5, since the motor 101, the gear 102, and the feed screw 103 are not used, the apparatus is small and light, and the positional accuracy is good because the gears and screws are not loose.
Since the front spring and the rear spring are structured to be extended and assembled, initial strain of the spring constant can be avoided.
[0007]
The invention according to claim 2 is characterized in that, in the invention according to claim 1, the front spring is used as a power supply path to the front coil, and the rear spring is used as a power supply path to the rear coil.
[0008]
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 is a cross-sectional view showing a lens driving device according to the present invention, FIG. 2 is a cross-sectional view showing a cross section of the lens driving device of FIG. 1 at 60 degrees, and FIG. 3 is an exploded view of the lens driving device of FIG. 4 is a perspective view, and FIG. 4 is a cross-sectional view showing the operation of the lens driving device of FIG.
[0010]
The lens driving device 1 includes a front lens 2, a front lens frame 31, a front support 3, a front coil 4, a front spring 5, a rear lens 6, a rear support 7, a rear coil 8, and a rear spring. 9, a magnet 10, a magnet support 21, and a yoke 11, the front coil 4 is wound around the outer gap between the magnet 10 and the yoke 11 in the circumferential direction, and the rear coil 8 is a magnet 10. and arranged wound inside the gap in the circumferential direction between the yoke 11, by applying a direct current to the front coil 4, to move by applying a forward driving force to the front lens 2, the DC current to the rear coil 8 by applying, it has become as to move the rear lens 6 by applying a forward driving force. In the present specification, the terms “front” and “rear” are used as appropriate. This indicates the positional relationship between the front and the rear relative to the subject from the camera.
[0011]
The ring-shaped D front support 3 is a molded product (electrical insulator) such as a synthetic resin, supports the front lens frame 31 at the top, includes the front coil 4 at the outer periphery rear, The outer end 5a of the front spring 5 is fixed, and projections 22 are provided at four positions every 90 degrees on the rear part of the inner periphery to act as a retaining member, and a rib 23 which is a small projection at the rear end. And sliding with the outer peripheral portion of the magnet support 21. The lead wire of the front coil 4 is soldered to the outer end portion 5a of the front spring 5 in the vicinity of the protrusion on the frontmost portion through the groove on the outer peripheral portion of the front support 3. The front lens frame 31 supports the front lens 2 at the inner peripheral portion.
[0012]
Similarly, the ring-shaped rear support 7 is a molded product (electrical insulator) such as a synthetic resin, supports the rear lens 6 at the center, and the rear coil 8 between the inner periphery and the arm 7a. The inner end portion 9b of the rear spring 9 is fixed to the protrusion on the bottom surface of the rear portion.
[0013]
The ring-shaped yoke 11 is a magnetic material such as soft iron and has a shape including an outer wall 11a, an inner wall 11b, and a bottom surface 11c. The outer wall 11a has a wall height larger than the inner wall 11b, and is spaced by 90 degrees from the inner wall 11b. The four cutouts 11d are provided, and the arm portion 7a of the rear support frame 7 passes through the cutout 11d.
[0014]
The magnet support 21 is a molded product (electrical insulator) made of synthetic resin, etc., and the upper and lower rings have a bowl shape supported by the four columns, and the four magnets 10 are fitted between the four columns. Is supported. For mass production, it is convenient to manufacture by integral molding. The magnet 10 is composed of four identical rectangular arc-shaped pieces, and is magnetized in the radial direction, and the bowl shape of the magnet support 21 ensures the rigidity of the structure that can counter the repulsive force of the magnet 10. .
[0015]
The magnet support 21 is fitted and fixed to the bottom portion 11c of the yoke 11 at the bottom, and the inner end portion 5b of the front spring 5 is fixed to the projection at the foremost portion, and the vertical groove 21a is formed at the inner peripheral portion near the projection. It has. A metal front terminal 32 is inserted into the vertical groove 21a, and is soldered to the inner end 5b of the front spring 5 at the foremost part, and the front / rear part penetrates the bottom surface 11c of the yoke 11. It acts as a power supply terminal to the front coil 4. A protrusion 21c is provided on the outer peripheral upper end of the peripheral portion, and acts as a retaining stopper that abuts against the protrusion 22 of the front support 3, and the side surface of the protrusion 21c is against the front spring 5 from a radial impact. It has a structure that mechanically suppresses the applied displacement. Elongated ribs are provided in the inner peripheral part (four places) of the peripheral part to facilitate sliding with the outer peripheral part of the rear support 7.
[0016]
The lead wire of the rear coil 8 penetrates the notch 11d along the side surface of the arm portion 7a and is soldered to the inner end portion 9b of the rear spring 9. The outer end portion 9a of the rear spring 9 is fixed to the protrusion at the bottom of the rearmost portion of the magnet support 21 and acts as a power supply terminal together with the spring retainer.
[0017]
The front coil 4 is disposed between the outer gap formed by the magnet 10 and the outer wall 11a. Similarly, the rear coil 8 is disposed between the inner gap formed by the magnet 10 and the inner wall 11b. A magnetic path returning to the magnet 10 via the bottom surface 11c and the inner wall 11b is formed.
[0018]
The front spring 5 and the rear spring 9 are metallic leaf springs such as phosphor bronze, have a spring property, and also act as a power feeding path to the front coil 4 and the rear coil 8. The outer end 5a of the front spring 5 is screwed into the protrusion of the front support 3 and pressed and fixed (heat caulking) with the spring retainer 5aa, and the inner end 5b is screwed into the protrusion of the magnet support 21 and springed. It is pressed and fixed with the presser 5bb. When the front support 3 is inserted into the yoke 11, the flange portion 3a of the front support 3 abuts against the upper surface portion of the outer wall 11a of the yoke 11, so that a step is generated between the outer end 5a and the inner end 5b. The front spring 5 is extended and assembled. The spring retainer 5bb has a shape protruding in the inner peripheral direction, and also plays a role of preventing the rear support 7 from coming off.
Each of the front spring 5 and the rear spring 9 has a substantially semicircular inner peripheral side portion and an outer peripheral side portion, and the inner peripheral side portion and the outer peripheral side portion are connected at one end in the circumferential direction. Two leaf springs having an inner end portion which is the other end in the circumferential direction of the portion and an outer end portion which is the other end in the circumferential direction of the outer peripheral side portion are combined into a substantially ring shape.
[0019]
The outer end 9a of the rear spring 9 is inserted into the protrusion of the magnet support 21 and is fixed by pressing with the spring retainer 9aa, and the inner end 9b is inserted into the protrusion of the rear support 7 with the spring retainer 9bb. Hold down and fix. When the rear support 7 is inserted into the yoke 11, the protrusions 7b (four locations) of the rear support 7 abut against the bottom surface 11c of the yoke 11, thereby creating a step between the outer end 9a and the inner end 9b. The rear spring 9 is also extended and assembled. Thus, since the front spring 5 and the rear spring 9 are stretched and assembled even when they are housed in the rearmost direction, it is possible to avoid initial distortion of the spring constant inherent to the leaf spring.
[0020]
Next, the operation of the present embodiment will be described based on the configuration described above. To assemble the lens driving device 1, first, the front coil 4 is assembled into the front support 3, the rear lens 6 and the rear coil 8 are assembled into the rear support 7, and each is fixed. The lead wire of the front coil 4 is fixed in advance along two outer peripheral recesses of the front support 3 and pulled out in advance. Further, the magnet 10 is incorporated in the magnet support 21.
[0021]
Next, the rear support 7 is assembled into the magnet support 21, the rear spring 9 and the spring retainers 9aa and 9bb are attached, and then the front support 3 and the front terminal 32 are assembled into the magnet support 21, the front spring 5 and the spring. The pressers 5aa and 5bb are attached. The lead wire of the rear coil 8 and the lead wire of the front coil 4 are connected by soldering to the inner end portion 9b and the outer end portion 5a, respectively, and the front terminal 32 is also connected by soldering.
[0022]
Subsequently, the yoke 11 is assembled into the magnet support 21 and fixed (press-fit) at the bottom surface 11c. The front lens 2 is incorporated in the front lens frame 31 in advance, and the front lens frame 31 is fixed to the forefront portion of the magnet support 21.
[0023]
As a result of the assembly connection described above, two external inputs to the front coil 4 are obtained as two front terminals 32 in the through-hole portion of the bottom surface 11c of the yoke 11, and the two external inputs to the rear coil 8 are It is obtained as two outer end portions 9 a of the rear spring 9.
[0024]
FIG. 4 shows a cross-sectional view when a DC current is applied to the front coil 4 and the rear coil 8 to operate the lens driving device 1 in the zoom state.
[0025]
When a current is applied to the front coil 4, an electromagnetic force forward (upward in FIG. 4) acts on the front lens 2, but the elastic force of the front spring 5 is rearward (downward in FIG. 4) in proportion to the displacement. ) Work. Therefore, the position of the front lens 2, that is, the moving distance forward is a point where the electromagnetic force and the elastic force are balanced.
[0026]
Thereby, the amount of movement of the front lens 2 can be determined by the amount of current applied to the front coil 4. Similarly, the amount of movement of the rear lens 6 can be determined by the amount of current applied to the rear coil 8.
[0027]
That is, the amount of movement of each of the front lens 2 and the rear lens 6 can be determined by the respective current amounts applied to the front coil 4 and the rear coil 8, so that the rear lens 6 is further rearward (downward in FIG. 4). In addition to the action of a fixed lens located inside the camera, the subject image can be zoomed and focused on an image plane such as a CCD.
[0028]
The rear support 7 is provided with a rear coil 8 between the inner peripheral portion and the arm portion 7a, and two lead wires of the rear coil 8 pass through the notch 11d along the side surface of the arm portion 7a. Since the structure is connected to the inner end 9bb of the rear spring 9, the rear support 7 can be disposed inside the magnet, and a small structure is realized.
[0029]
The front support 3 includes ribs 23 that are extremely small protrusions at four positions at 90 ° intervals at the rearmost portion of the protrusions 22 and slides on the outer periphery of the magnet support 21. Since the four ribs 23 are opposed to each other, they can be molded with high precision and have a small sliding area, so that the front lens 2 can be moved smoothly and with less blur.
[0030]
The magnet support 21 is provided with a protrusion 21c at the outer peripheral upper end, and acts as a retaining stopper that abuts against the protrusion 22 of the front support frame 3 to prevent the front support 3 from falling off. The spring 5 has a structure that mechanically suppresses the displacement applied from the radial impact.
[0031]
Further, since the magnet support 21 has a hook shape in which the upper and lower rings are supported by the four support columns, a firm structure is realized against the repulsive force of the magnet 10.
[0032]
Furthermore, since the front spring 5 and the rear spring 9 are extended and assembled even when they are housed in the rearmost position, initial strain of the spring constant can be avoided.
[0033]
【The invention's effect】
In the first aspect of the invention, the rear lens can be disposed inside the magnet, and the amount of movement of each of the front lens and the rear lens can be controlled by controlling the amount of current applied. The structure can be made small and inexpensive, and the strength can be improved.
[0034]
According to the second aspect of the invention, the same effects as those of the first aspect of the invention can be achieved, and the distortion of the spring constant can be suppressed to improve the accuracy of the positions of the front lens and the rear lens.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a lens driving device according to the present invention.
FIG. 2 is a cross-sectional view showing a cross section of the lens driving device of FIG.
3 is an exploded perspective view of the lens driving device of FIG. 1. FIG.
4 is a cross-sectional view showing the operation of the lens driving device of FIG. 1. FIG.
FIG. 5 is a perspective view showing a conventional lens driving device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lens drive device 2 Front lens 3 Front support body 4 Front coil 5 Front spring 6 Rear lens 7 Back support body 8 Back coil 9 Back spring 10 Magnet 11 Yoke 21 Magnet support body 31 Front lens frame

Claims (2)

A front lens, a front lens frame that supports the front lens, a front support that supports the front lens frame, a front coil that is attached to the front support, a front spring that is attached to the front support, a rear lens, and a rear A rear wall that supports the lens, a rear coil that is attached to the rear support, a rear spring that is attached to the rear support, a magnet, a magnet support, an inner wall, and an outer wall are formed in a cylindrical shape to form a bottom wall The magnet support is provided between the inner wall and the outer wall of the yoke, and the magnet is arranged with a gap between each wall, and the magnet is magnetized in the radial direction. There, the front coil is arranged by winding the outer gap in the circumferential direction between the magnet and the yoke outer wall, the rear coil, the inner gap between the magnet and the yoke inner wall Circumferentially winding arranged to impart longitudinal direction of the driving force to the front lens by applying a current to the forward coil, it is moved to a position where balance the front lens and the elastic force of the front spring, the rear coil A lens driving device that applies a driving force in the front-rear direction to the rear lens by applying an electric current, and moves the rear lens to a position that balances the elastic force of the rear spring,
Each of the front spring and the rear spring has a substantially semicircular inner peripheral side portion and an outer peripheral side portion, and the inner peripheral side portion and the outer peripheral side portion are connected at one end in the circumferential direction. Two leaf springs having an inner end portion which is the other end in the circumferential direction and an outer end portion which is the other end in the circumferential direction on the outer peripheral side portion are combined into a substantially ring shape. It is flat and assembled in a state where it is stretched and elastically deformed to create a step between the inner end and the outer end during assembly. The outer end of the front spring is fixed to the front end of the front support. The lens is characterized in that the portion is fixed to the front end of the magnet support, the rear spring has an inner end fixed to the rear end of the magnet support, and an outer end fixed to the rear end of the rear support. Drive device.   2. The lens driving device according to claim 1, wherein the front spring is used as a power supply path to the front coil, and the rear spring is used as a power supply path to the rear coil.

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