KR20110097551A - Lens driving device - Google Patents

Abstract

To move the lens holder only in the optical axis direction without sliding the lens holder relative to the other member.
The coil shaped shape memory alloy spring 24 disposed between the lens holder 18 and the housing at the bottom of the lens holder 18 has an outer circumferential diameter of a size substantially the same as the outer circumferential diameter of the lens holder 18. The elastic member 20 disposed between the lens holder 18 and the housing supports the lens holder 18 so as to be displaceable only in the optical axis O direction with the lens holder 18 positioned in the radial direction.

Description

Lens drive device {LENS DRIVING DEVICE}

The present invention relates to a lens driving apparatus, and more particularly to a lens driving apparatus using a shape memory alloy in an actuator.

Background Art [0002] A linear actuator using a shape memory alloy (SMA) is known as an autofocus actuator or a zoom actuator of a camera.

For example, Japanese Unexamined Patent Application Publication No. 2005-275270 (Patent Document 1) discloses a lens barrel that can move only a part of lenses for focusing, and is relatively simple in construction and small in size. The lens barrel disclosed in Patent Literature 1 includes a cylindrical body, a fixed lens provided at an upper end of the cylindrical body, a movable lens portion provided to be movable in the optical axis direction (sliding motion) at the inner peripheral portion of the lower part of the cylindrical body, and the movable lens portion in the optical axis direction. It has a moving means for moving to. The movable lens portion is configured by holding the lens in the frame body (lens holder). The movable lens part is arrange | positioned so that the outer peripheral surface of a frame body (lens holder) can slide the inner peripheral surface of a cylinder. The moving means has a shape memory alloy spring provided below the frame (lens holder) as a deformation part. In addition, the lens barrel has a bias spring which holds the movable lens portion at a predetermined position on an upper side of the frame body (lens holder) as the holding means.

In addition, Japanese Patent Laid-Open No. 2006-98829 (Patent Document 2) discloses a lens driving apparatus that can be moved quickly and smoothly, and is miniaturized to be mounted on a portable information terminal. The lens driving device disclosed in Patent Document 2 includes a lens frame (lens holder) for holding a lens, a fixed frame having a cylindrical support portion for supporting the lens frame (lens holder) to be movable only in the optical axis direction, and the optical axis direction It is provided with a coil spring that can be stretched and contracted. The coil spring is disposed concentrically and exposed to the outside of the cylindrical support portion, and further includes a shape memory alloy spring formed by a shape memory alloy which expands and contracts in the optical axis direction due to a temperature change caused by energization / non-energization. The cylindrical outer circumferential surface of the lens frame (lens holder) is freely fitted with a sliding motion on the inner circumferential surface of the cylindrical support of the fixed frame.

As an embodiment disclosed in Patent Document 2, the coil spring includes a front coil spring and a rear coil spring arranged concentrically around the optical axis on the outer side of the cylindrical support part. The front coil spring and the rear coil spring press the lens frame from the front side and the rear side in the optical axis direction. At least one of the front coil spring and the rear coil spring is formed of a shape memory alloy.

In Patent Document 2, one of the front coil springs and the rear coil springs is formed of a shape memory alloy extending at the time of energization, and the other is formed of a shape memory alloy contracting at the time of energization, so that these front coil springs and the rear coils are formed. Embodiments using both springs as a coil spring for driving are disclosed.

Japanese Patent Laid-Open No. 2005-275270 (paragraphs 0014 to 0029, Fig. 1) Japanese Patent Laid-Open No. 2006-98829 (paragraphs 0009 to 0020, 0030, Figs. 1 to 5)

In the lens barrel disclosed in Patent Document 1 described above and the lens driving apparatus disclosed in Patent Document 2, there are problems as described below.

In patent document 1, the frame body (lens holder) of a movable lens part is arrange | positioned so that sliding movement is possible in the inner peripheral part of a cylinder. That is, the cylinder functions as a guide means for guiding the movable lens portion only in the optical axis direction. Therefore, a frictional force acts between the frame body (lens holder) of the movable lens part and the inner peripheral part of the cylinder. In such a guide means, the shape memory alloy spring needs to move the movable lens part only in the optical axis direction in order to resist this frictional force. As a result, one having a large pressing force (driving force) must be used as the shape memory alloy spring. In other words, the shape memory alloy spring becomes expensive.

Moreover, in the lens drive device disclosed in Patent Document 2, the shape memory alloy spring is disposed by exposing to the outside of the cylindrical support portion. As a result, the size of the lens drive increases. On the contrary, when the size of the lens drive device is reduced in size, the diameter of the lens held in the lens frame (lens holder) is also reduced.

Moreover, similarly to the said patent document 1, also in patent document 2, the sliding motion is arrange | positioned freely in the inner peripheral surface of the cylindrical support part of a fixed frame. That is, the cylindrical support of the fixed frame acts as a guide means for guiding the lens frame (lens holder) only in the optical axis direction. Therefore, a frictional force acts between the cylindrical outer peripheral surface of the lens frame (lens holder) and the inner peripheral surface of the cylindrical support of the fixed frame. Therefore, the shape memory alloy spring needs to move the lens frame (lens holder) only in the optical axis direction in order to resist this frictional force. As a result, one having a large pressing force (driving force) must be used as the shape memory alloy spring. In other words, the shape memory alloy spring becomes expensive.

Accordingly, an object of the present invention is to provide a lens driving apparatus capable of moving the lens holder only in the optical axis direction without sliding the lens holder holding the lens with respect to the other member.

Another object of the present invention is to provide a lens driving apparatus capable of reducing the size in width and width without reducing the lens diameter.

Other objects of the present invention will become clear as the description proceeds.

According to the present invention, the lens holder 18 holding the lens barrel 11, the housing 12 supporting the lens holder so as to be movable only in the optical axis O direction, and the lens holder 18 are supported by the optical axis O. In the lens driving apparatus (10; 10A; 10B) having a moving means for moving in the direction of < RTI ID = 0.0 >) < / RTI > and a guide means for guiding the lens holder 18 to be movable only in the optical axis O direction, the moving means is a lens holder. At the bottom of 18, a coil-shaped shape memory alloy spring 24 is disposed between the lens holder 18 and the housing 12, the shape memory alloy spring 24 of the lens holder 18 Having an outer circumferential diameter of a size substantially the same as the outer circumferential diameter, the guiding means includes an elastic member 20; 20A disposed between the lens holder 18 and the housing 12, the elastic member having the lens holder 18 To be displaceable only in the optical axis O direction with the The lens driving apparatus as ranging can be obtained.

In the lens driving device (10; 10A; 10B) according to the present invention, the elastic member (20; 20A) is positioned near the center of gravity (Cg) position of the lens movable portion including the lens barrel (11) and the lens holder (18). It is preferable that it is comprised by the leaf springs 21, 21A; 22, 22A which pass and extend in the plane orthogonal to the optical axis O direction. The housing 12 should just be comprised of the actuator base 14 arrange | positioned at the lower side of the lens holder 18, and the upper cover 16 which covers the lens holder 18 from the upper side. In this case, the leaf spring is composed of first and second leaf springs 21, 21A; 22, 22A, one end of each of the first and second leaf springs is fixed to the lens holder 18, and the other end is It is sufficient to be fixed to the actuator base 14. The spring constants of the first and second leaf springs 21A, 22A are preferably set to correct the inclination of the lens holder 18 during operation with respect to the optical axis O direction. The lens drive device 10A may further have a coil spring 28 disposed between the lens holder 18 and the upper cover 16.

In addition, the code | symbol in the said parentheses is attached in order to make understanding easy, It is a matter of course that it is only an example and is not limited to these.

In the present invention, the coil-shaped shape memory alloy spring, which is a moving means, is disposed between the lens holder and the housing at the bottom of the lens holder, and has an outer circumferential diameter of a size substantially the same as the outer circumferential diameter of the lens holder, thereby reducing the lens diameter. The size can be reduced vertically and horizontally. In addition, the elastic member serving as the guide means is disposed between the lens holder and the housing so that the lens holder can be displaced only in the optical axis direction while the lens holder is positioned in the radial direction, so that the lens holder is not slidably moved relative to the other member. Can be moved only in the optical axis direction.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view which looked at the external appearance of the lens drive apparatus which concerns on 1st Embodiment of this invention at an oblique front upward.
FIG. 2 is a perspective view of the lens driving apparatus shown in FIG. 1 omitted from the front and obliquely seen from above.
FIG. 3 is a perspective view of the lens driving apparatus shown in FIG. 2, with the upper cover omitted, and viewed obliquely from above.
4 is an exploded perspective view of the lens driving device shown in FIG. 2 as viewed obliquely from above.
5 is a perspective view illustrating a state in which the first and second leaf springs used in the lens driving apparatus shown in FIG. 1 are attached to the lens holder.
FIG. 6 is a partial cross-sectional perspective view of a portion of the lens driving apparatus illustrated in FIG. 3;
FIG. 7 is an enlarged cross-sectional view illustrating an enlarged main part of FIG. 6.
8 is a perspective view showing a lens movable portion and a lens driving portion used in the lens driving apparatus according to the second embodiment of the present invention.
9 is a perspective view showing a lens driving unit used in the lens driving apparatus according to the third embodiment of the present invention.
10 is a perspective view showing a lens movable portion and a lens driving portion used in the lens driving apparatus according to the fourth embodiment of the present invention.
FIG. 11 is a perspective view showing a lens driving unit used in the lens driving apparatus according to the fourth embodiment of the present invention. FIG.
It is explanatory drawing which shows typically and exaggerated the inclination of the wire rod which comprises the coil of the shape memory alloy for pressure and the shape memory alloy spring which concerns on 4th Embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

With reference to FIGS. 1-4, the lens drive apparatus 10 by 1st Embodiment of this invention is demonstrated. 1 is a perspective view of the lens driving apparatus 10 viewed obliquely from above. 2 is a perspective view of the lens driving device 10 viewed obliquely from above in a state where the lens barrel 11 is omitted. 3 is a perspective view of the lens driving device 10 viewed obliquely from above in a state where the lens barrel 11 and the upper cover 16 are omitted. 4 is an exploded perspective view of the lens driving device 10 viewed obliquely from above in a state where the lens barrel 11 is omitted.

Here, as shown in Figs. 1 to 4, rectangular coordinate systems (X, Y, Z) are used. 1 to 4, in the Cartesian coordinate system (X, Y, Z), the X axis direction is the front-rear direction (depth direction), the Y axis direction is the left-right direction (width direction), and the Z axis The direction is the vertical direction (height direction). In the example shown in FIGS. 1-4, the up-down direction Z is an optical axis O direction of a lens.

In an actual use situation, however, the optical axis O direction, that is, the Z axis direction, becomes the front-rear direction. In other words, the upper direction of the Z axis is the forward direction, and the lower direction of the Z axis is the rear direction.

The illustrated lens driving device 10 is provided in, for example, a mobile phone with an autofocusable camera. The lens driving apparatus 10 includes a lens barrel (lens assembly) 11 in which an autofocus lens AFL, which is a movable lens, is incorporated. The lens driving device 10 is for moving the lens barrel 11 only in the optical axis O direction.

As shown in FIG. 1, the lens driving device 10 includes an approximately rectangular parallelepiped body (housing) 12 covering the lens barrel 11. In other words, the lens barrel 11 is arranged in the housing (housing) 12. The housing (housing) 12 includes an actuator base 14 and an upper cover 16.

In addition, although not shown in figure, the imaging element arrange | positioned at the board | substrate is mounted in the center part of the actuator base 14. This imaging element picks up an image of an object formed by the movable lens AFL and converts it into an electrical signal. The imaging device is configured by, for example, a charge coupled device (CCD) type image sensor, a complementary metal oxide semiconductor (CMOS) type image sensor, or the like.

The lens driving device 10 includes a lens holder 18 holding the lens barrel 11. In other words, the lens barrel 11 is held and fixed in the lens holder 18. In detail, the lens holder 18 has a substantially cylindrical shape. The lens holder 18 includes a large diameter cylindrical portion 182 on the upper side (the subject side) of the optical axis O direction, and a small diameter cylindrical portion 184 on the lower side (imaging element side) of the optical axis O direction. . The outer diameter of the small diameter cylindrical portion 184 is smaller than the outer diameter of the large diameter cylindrical portion 182 and larger than the inner diameter of the large diameter cylindrical portion 182. The inner diameter of the small diameter cylindrical portion 184 is smaller than the inner diameter of the large diameter cylindrical portion 182. The large diameter cylindrical portion 182 and the small diameter cylindrical portion 184 are coupled to each other with a step 185.

A female screw (not shown) is formed on the inner circumferential wall of the large diameter cylindrical portion 182 of the lens holder 18. On the other hand, the outer circumferential wall of the lens barrel 11 is formed with a male screw (not shown) that is screwed to the female screw. Therefore, in order to mount the lens barrel 11 to the lens holder 18, the lens barrel 11 is rotated about the optical axis O with respect to the lens holder 18 and screwed along the optical axis O direction, thereby The barrel 11 is accommodated in the lens holder 18 and bonded together by an adhesive agent or the like.

The lens holder 18 is supported in the housing 12 so as to be movable only in the optical axis O direction as described later. The lens movable parts 11 and 18 are formed by the combination of the lens barrel 11 and the lens holder 18.

Four engaging members 186 are provided on the outer circumferential wall of the large diameter cylindrical portion 182 of the lens holder 18. These four engaging members 186 are for hanging the first and second leaf springs 21 and 22 which will be described later. The four engaging members 186 each have four engaging projections 186a which protrude downward from the large diameter cylindrical portion 182 of the lens holder 18.

The first and second leaf springs 21 and 22 function as the elastic member 20 disposed between the lens holder 18 and the housing 12. Each of the first and second leaf springs 21 and 22 is made of beryllium copper, phosphor bronze, and the like.

In addition to FIGS. 1 to 4, the attachment state of the first and second leaf springs 21 and 22 will be described with reference to FIGS. 5 to 7. 5 is a perspective view illustrating a state in which the first and second leaf springs 21 and 22 are attached to the lens holder 18. FIG. 6 is a partial cross-sectional perspective view of a portion of the lens driving apparatus illustrated in FIG. 3; FIG. 7 is an enlarged cross-sectional view illustrating an enlarged main part of FIG. 6.

In detail, the actuator base 14 has four protrusion parts 142 which protrude upward in the up-down direction Z at four corners. The four protrusions 142 each have four protrusions 142a that protrude upward.

The 1st leaf spring 21 is arrange | positioned in front of the front-back direction X, and the 2nd leaf spring 22 is arrange | positioned at the back of the front-back direction X. As shown in FIG.

The first leaf spring 21 has a first arc portion 211 extending in an arc shape from the front to the left and right directions (Y) and a first end portion protruding forward from both left and right ends of the first arc portion 211. Has (212). The first both ends 212 have a pair of holes 212a into which two protrusions 142a provided in front of the four protrusions 142a are fitted. The first arc portion 211 is disposed at the step 185 of the lens holder 18. The first circular arc portion 211 has a pair of engaging grooves 211a engaged with two engaging projections 186a provided in front of the four engaging projections 186a. The first leaf spring 21 has one end (first arc portion 211) fixed to the lens holder 18 in front of the lens holder 18, and the other end (first both ends 212) is provided with an actuator base ( 14).

Similarly, the second leaf spring 22 includes a second circular arc portion 221 extending in an arc shape from the rear to the left and right directions Y, and a second protrusion spring protruding rearward from both left and right ends of the second circular arc portion 221. It has two ends 222. The second both ends 222 have a pair of holes 222a into which two protrusions 142a installed at the rear of the four protrusions 142a are fitted. The second arc portion 221 is disposed at the step 185 of the lens holder 18. The second circular arc portion 221 has a pair of engaging grooves 221a which are fitted with two engaging projections 186a installed at the rear of the four engaging projections 186a. As for the 2nd leaf spring 22, the one end (2nd circular arc part 221) is fixed to the lens holder 18 at the back of the lens holder 18, and the other end (2nd both ends 222) is an actuator base ( 14).

Therefore, the elastic member 20 which consists of the combination of the 1st and 2nd leaf springs 21 and 22 supports so that displacement is possible only in the optical axis O direction in the state which positioned the lens holder 18 in the radial direction. In other words, the elastic member 20 functions as guide means for guiding the lens holder 18 to be movable only in the optical axis O direction.

5 and 6, the elastic member 20 passes near the center of gravity Cg position of the lens movable parts 11 and 18 and extends in a plane perpendicular to the optical axis O direction. It is.

By such a configuration, the lens movable parts 11 and 18 are movable only in the optical axis O direction with respect to the housing (housing) 12.

The lens drive device 10 includes a coil-shaped shape memory alloy spring 24 disposed between the lens holder 18 and the housing 12 at the bottom of the lens holder 18.

In detail, as shown in FIG. 6 and FIG. 7, the actuator base 14 has a diameter substantially the same as the diameter (outer diameter and inner diameter) of the small diameter cylindrical portion 184 of the lens holder 18. The branch has a cylindrical portion 144. The actuator base 14 has an annular groove 146 formed along the outer circumferential wall of the cylindrical portion 144. The shape memory alloy spring 24 is formed between the annular groove 146 and the step 185 of the lens holder 18 and the cylindrical portion of the small diameter cylindrical portion 184 of the lens holder and the actuator base 14 ( It is arrange | positioned around the outer peripheral wall of 144. The shape memory alloy spring 24 has an outer circumference diameter of a size substantially the same as the outer circumference diameter of the lens holder 18.

As is well known, the "shape memory alloy" is a metal having a property in which a given strain distortion becomes zero in a specific temperature range and is restored to its original shape. The shape memory alloy is made of, for example, a TiNi alloy.

The elastic member 20 acts to press the lens holder 18 downward along the optical axis O direction. On the other hand, the shape memory alloy spring 24 is extended when it is energized from a drive circuit (not shown). As a result, the lens holder 18 moves upward along the optical axis O direction against the pressing force in the downward direction of the elastic member 20.

On the other hand, when power supply to the shape memory alloy spring 24 is stopped, the shape memory alloy spring 24 is naturally cooled. As a result, the shape memory alloy spring 24 is contracted by the downward force of the elastic member 20. As a result, the lens holder 18 moves downward along the optical axis O direction.

That is, the shape memory alloy spring 24 is stretched and contracted in the optical axis O direction by the temperature change caused by the energization / non-energization, and functions as a moving means for moving the lens holder 18 in the optical axis O direction.

The combination of the elastic member 20 and the shape memory alloy spring 24 supports the lens movable portions 11 and 18 so as to be movable in the optical axis O direction, while driving the lens movable portions 11 and 18. , 24).

Both ends 24a of the shape memory alloy spring 24 are electrically connected to the pair of electrodes 26. This pair of electrodes 26 is for flowing a current through the shape memory alloy spring 24.

The lens drive units 20 and 24 and the lens movable units 11 and 18 are arranged side by side with respect to the optical axis O, as shown in FIG. 6. Therefore, the lens drive device 10 can be reduced in size.

The lens driving apparatus 10 according to the first embodiment described above has the following effects.

Since the elastic member 20 disposed between the lens holder 18 and the housing 12 is used as the guide means, the lens holder 18 is moved to the optical axis without sliding the lens holder 18 with respect to the other members. Can only move in the direction of O).

Since the shape memory alloy spring 24 is disposed at the bottom of the lens holder 18, the size of the lens drive device 10 is reduced in size without reducing the lens diameter of the autofocus lens AFL, which is a movable lens. You can. As a result, a large diameter of the lens diameter of the autofocus lens AFL can be reduced, and a high resolution camera can be coped with.

Moreover, since the shape memory alloy spring 24 of the size equivalent to the outer peripheral diameter of the lens movable parts 11 and 18 is used, torque (force) is equally given to a focus direction (optical axis O direction), and an autofocus lens ( Operation defects such as the inclination of the AFL) can be suppressed.

In addition, since the elastic member 20 is disposed so as to pass near the center of gravity Cg position of the lens movable parts 11 and 18 and extend in a plane perpendicular to the optical axis O direction, autofocus at the time of focusing is performed. The inclination of the lens AFL can be suppressed.

Moreover, since the shape memory alloy spring 24 is arrange | positioned in the coil shape wound by multiple layers, even when thrust of the shape memory alloy itself is small, thrust loss can be suppressed by making it into several layer shape (coil shape).

With reference to FIG. 8, the lens drive apparatus 10A which concerns on 2nd Embodiment of this invention is demonstrated. 8 is a perspective view showing the lens movable portion and the lens driving portion of the lens driving apparatus 10A.

The illustrated lens drive device 10A operates with the same configuration as the lens drive device 10 shown in Figs. 1 to 4, except that the configuration of the lens drive part is different as will be described later. The same reference numerals are given to the same components as those of the lens driving apparatus 10, and their description is omitted, and only the differences will be described below.

In the lens drive device 10 shown in Figs. 1 to 4, the lens drive part is composed of a combination of the elastic member 20 and the shape memory alloy spring 24. On the other hand, in the lens drive apparatus 10A shown in FIG. 8, the lens drive part is further comprised by the coil spring 28 in addition to the elastic member 20 and the shape memory alloy spring 24. As shown in FIG. The coil spring 28 is made of stainless steel (SUS).

The coil spring 28 is disposed above the large diameter cylindrical portion 182 of the lens holder 18. That is, the coil spring 28 is arrange | positioned between the large diameter cylindrical part 182 of the lens holder 18, and the upper cover 16 (refer FIG. 1, FIG. 2, FIG. 4). The coil spring 28 has an outer diameter of a size substantially the same as the outer diameter of the lens holder 18. The coil spring 28 functions as a pressing spring which presses the lens movable parts 11 and 18 downward along the optical axis O direction.

As described above, in the lens driving apparatus 10 shown in FIGS. 1 to 4, the pressing means is constituted only by the elastic member 20. In the lens driving apparatus 10A shown in FIG. 8, the pressing means is used. It consists of the combination of the elastic member 20 and the coil spring 28. As shown in FIG. Thereby, it becomes possible to adjust the pressing force which presses the lens movable parts 11 and 18 downward along the optical axis O direction.

With reference to FIG. 9, the lens drive apparatus 10B which concerns on 3rd Embodiment of this invention is demonstrated. 9 is a perspective view showing the lens driver of the lens driver 10B. The lens driving device 10B shown in FIG. 1 operates with the same configuration as the lens driving device 10 shown in FIGS. 1 to 4 except that the structure of the elastic member is different, as will be described later. Therefore, the reference numeral 20A is attached to the elastic member. The same reference numerals are given to the same components as those of the lens driving apparatus 10, and only the differences will be described below.

Since the shape memory alloy spring 24 has a coil shape, when the lens holder 18 is moved by the expansion and contraction of the shape memory alloy spring 24 in the optical axis O direction, as shown by arrow A in FIG. 9. Likewise, the lens holder 18 may be driven in a slightly tilted state with respect to the optical axis O direction. In detail, the one (the left side of FIG. 9; the front side of the front-back direction X) which the number of windings (the number of layers) of the shape memory alloy spring 24 has the smaller the number (the number of floors) which the winding | winding (the right of FIG. 9; Since the driving force (thrust force) is large compared with the back side of the front-back direction X, the lens holder 18 is driven in the slightly tilted state as shown by the arrow A of FIG.

Thus, the elastic member 20A shown in FIG. 9 is provided with correction means for correcting a slight inclination of the lens holder 18 as described above.

More specifically, the elastic member 20A has a first leaf spring 21A and a second leaf spring 22A having different spring constants from each other. In the example shown in FIG. 9, the 2nd of the 2nd leaf spring 21A arrange | positioned by the 1st spring constant of the 1st leaf spring 21A arrange | positioned in the front-back direction X front side behind the front-back direction X is shown. It is set to be larger than the spring constant. This makes the shape memory alloy spring 24 more difficult to move than the one where the number of times of winding (the number of floors) is smaller. As a result, the inclination of the lens holder 18 can be eliminated, and the lens holder 18 can be moved up and down along the optical axis O direction.

In addition, various methods are conceivable for the method of changing the first and second spring constants of the first and second leaf springs 21A and 22A. For example, there is a method of changing at least one of the material, shape, and thickness of the leaf spring.

With reference to FIG. 10, the lens drive apparatus 10C which concerns on 4th Embodiment of this invention is demonstrated. 10 is a perspective view showing a lens movable portion and a lens driving portion of the lens driving apparatus 10C.

The illustrated lens drive device 10C operates with the same configuration as the lens drive device 10 shown in Figs. 1 to 4, except that the configuration of the lens drive part is different as will be described later. The same reference numerals are given to the same components as those of the lens driving apparatus 10, and their description is omitted, and only the differences will be described below.

In the lens drive device 10 shown in Figs. 1 to 4, the lens drive part is composed of a combination of an elastic member 20 and a shape memory alloy spring 24 for driving. On the other hand, in the lens drive device 10C shown in FIG. 10, the lens drive part is further provided with a coil-shaped pressurized shape memory alloy 30 in addition to the elastic member 20 and the shape memory alloy spring 24. Consists of.

The shape memory alloy 30 for press is formed in substantially the same aspect as the shape memory alloy spring 24 for a drive. That is, the pressurized shape memory alloy 30 has the coil shape wound in multiple layers similarly to the shape memory alloy spring 24, and is formed of the same shape memory alloy as the shape memory alloy spring 24. As shown in FIG. However, the big difference between the pressurized shape memory alloy 30 and the shape memory alloy spring 24 is that the shape memory alloy spring 24 has both ends 24a electrically connected to the pair of electrodes 26. On the other hand, the shape memory alloy 30 for pressurization is not connected to such an electrode, and is not energized.

These shape memory alloy springs 24 and the shape memory alloy 30 for pressurization increase and expand in a high temperature environment, and shrink in a low temperature environment in a normal temperature environment. The term " high temperature environment " used herein means an environment having an external temperature of about 70 ° C or higher when a TiNi alloy is employed as the shape memory alloy. In addition, "normal temperature environment" means the environment whose external temperature is about 70 degrees C or less, for example, when TiNi alloy is employ | adopted as a shape memory alloy.

The shape memory alloy 30 for press is arrange | positioned above the large diameter cylindrical part 182 of the lens holder 18. As shown in FIG. That is, the shape memory alloy 30 for press is arrange | positioned between the large diameter cylindrical part 182 of the lens holder 18, and the upper cover 16 (refer FIG. 1, FIG. 2, FIG. 4). The pressing shape memory alloy 30 has an outer circumferential diameter of a size substantially the same as the outer circumferential diameter of the lens holder 18, and has an outer circumferential diameter that is the same size as the outer circumferential diameter of the shape memory alloy spring 24.

The number of windings (number of layers) of the shape memory alloy 30 for pressurization (the left side of FIG. 11; the front-back direction X front side) and the number of windings (number of layers) of the shape memory alloy spring 24 (FIG. 11) The left side of 11; the front and rear directions X and the shape memory alloy 30 and the shape memory alloy spring 24 for pressure are arranged so as to face each other in the optical axis O direction.

In other words, the smaller the number of windings (number of layers) of the shape memory alloy 30 for press (right side in FIG. 11; the rear side of the front and rear direction X) and the number of windings (number of layers) of the shape memory alloy spring 24 The pressing shape memory alloy 30 and the shape memory alloy spring 24 are arranged so that the smaller one (right side in FIG. 11; rear side in the front and rear directions X) faces each other in the optical axis O direction.

In detail, since the pressurized shape memory alloy 30 and the shape memory alloy spring 24 have a coil shape, the pressurized shape memory alloy 30 and the shape memory alloy spring 24 expand | extend under high temperature environment. In this case, there is a difference in thrust between the one with the smallest number of turns (layers) and the one with the large number of turns (layers). For example, the number of windings (number of layers) of the pressurized shape memory alloy 30 and the number of windings (number of layers) of the shape memory alloy spring 24 face each other in the optical axis O direction. In the case where the same arrangement relationship is employed, the lens holder 18 may be inclined with respect to the optical axis O direction. So, in this embodiment, in order to prevent generation | occurrence | production of the inclination of the lens holder 18 in such a high temperature environment, between the above-mentioned press shape memory alloy 30 and the shape memory alloy spring 24, Arrangement relationship is adopted.

Moreover, it is designed so that the winding direction of the coil of the pressurized shape memory alloy 30 and the winding direction of the coil of the shape memory alloy spring 24 may be reversed.

In detail, since the wire which comprises each coil of the pressurized shape memory alloy 30 and the shape memory alloy spring 24 draws a spiral as shown in FIG. 12, it is inclined a little with respect to a horizontal plane. Therefore, when the winding direction of the coil of the shape memory alloy 30 for presses matches the winding direction of the coil of the shape memory alloy spring 24, for example, in the high temperature environment, the shape memory alloy 30 and the shape for pressure presses are formed. When the memory alloy spring 24 is extended, due to the inclination of the wire rod constituting the coil described above, the lens holder 18 may be inclined with respect to the optical axis O direction. So, in this embodiment, in order to prevent the inclination of the lens holder 18 in such a high temperature environment, as mentioned above, the winding direction of the coil of the shape memory alloy 30 for press, and shape The winding direction of the coil of the memory alloy spring 24 is designed to be reversed.

Next, the operation of the lens driving unit in the room temperature environment, the high temperature environment, and the energization of the shape memory alloy spring 24 will be described below.

First, under normal temperature environment, since the pressing shape memory alloy 30 does not extend as described above, it functions as a pressing spring for pressing the lens movable parts 11 and 18 downward along the optical axis O direction. As a result, the pressing force which presses the lens movable parts 11 and 18 downward along the optical axis O direction can be adjusted.

Next, in the high temperature environment, the shape memory alloy spring 24 is extended as its temperature rises as described above. At this time, the pressurized shape memory alloy 30 also increases in temperature and elongates, so that the thrust of the shape memory alloy spring 24 acting on the lens movable portions 11 and 18 toward the optical axis O direction upwards. The thrust of the pressurized shape memory alloy 30 acting on the lens movable portions 11 and 18 toward the lower side in the optical axis O direction becomes equal to the displacement of the lens movable portions 11 and 18 in the optical axis O direction. Can be prevented.

Thus, the shape memory alloy 30 for pressurization functions as a thrust adjustment means which adjusts the thrust acting on the lens movable parts 11 and 18. As shown in FIG.

Next, when the shape memory alloy spring 24 is energized, the shape memory alloy spring 24 rises in temperature and extends in the optical axis O direction. At this time, since the pressurized shape memory alloy 30 is not energized as described above, it functions only as a pressurizing spring pressurized downward. As a result, the lens holder 18 resists the pressing force in the downward direction of the shape memory alloy 30 for pressing, and moves upward along the optical axis O direction. On the other hand, when power supply to the shape memory alloy spring 24 is stopped, the shape memory alloy spring 24 is naturally cooled. As a result, the shape memory alloy spring 24 is contracted by the downward pressing force of the shape memory alloy 30 for pressurization. The lens holder 18 moves downward along the optical axis O direction.

As described above, in the fourth embodiment of the present invention, the pressurized shape memory alloy 30 is provided as the lens driving portion, thereby moving the lens movable portions 11 and 18 downward along the optical axis O in the normal temperature environment. It is not only possible to adjust the pressing force to press, but also to prevent displacement of the lens movable parts 11 and 18 in the optical axis O direction in a high temperature environment.

As mentioned above, although this invention was demonstrated according to the preferable embodiment, it is clear that various changes are possible for those skilled in the art within the range which does not deviate from the mind of this invention. For example, in the above-mentioned embodiment, although the elastic member is comprised by two leaf springs, it may consist of only one leaf spring and may consist of three or more sheets of leaf springs.

10, 10A, 10B, 10C... Lens driving device 11. Lens Barrel (Lens Assembly)
12... Housing 14. Actuator Base
16... Upper cover 18... Lens holder
20, 20A... Elastic members 21, 21A... 1st leaf spring
22, 22A... Second leaf spring 24... Shape memory alloy spring
26... Electrode 28.. Coil Spring (Pressure Spring)
30... Pressurized shape memory alloy O. Optical axis of the lens
Cg… Center of gravity of lens moving part AFL. Auto focus lens

Claims (5)

A lens holder for holding the lens barrel, a housing for supporting the lens holder movably only in the optical axis direction, moving means for moving the lens holder in the optical axis direction, and the lens holder in the optical axis direction only In the lens driving device having a guide means for guiding the guide,
The moving means includes a coil-shaped shape memory alloy spring disposed between the lens holder and the housing at the bottom of the lens holder, the shape memory alloy spring having a size substantially the same as the outer diameter of the lens holder. Has a circumferential diameter,
The guide means includes an elastic member disposed between the lens holder and the housing, wherein the elastic member supports the lens holder so as to be displaceable only in the optical axis direction while the lens holder is positioned in the radial direction. Drive system. 2. The elastic member according to claim 1, wherein the elastic member comprises a leaf spring passing near the center of gravity position of the lens movable portion formed of the lens barrel and the lens holder and extending in a plane perpendicular to the optical axis direction. Lens drive. The said housing has an actuator base arrange | positioned at the lower side of the said lens holder, and the upper cover which covers the said lens holder from the upper side,
The leaf spring is composed of the first and second leaf spring,
Each of the first and second leaf springs has one end fixed to the lens holder and the other end fixed to the actuator base. 4. The lens drive device according to claim 3, wherein the spring constants of the first and second leaf springs are set to correct the inclination of the lens holder during operation with respect to the optical axis direction. 5. The lens driving apparatus according to claim 3 or 4, further comprising a coil spring disposed between the lens holder and the upper cover.

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