KR101005774B1 - Camera Actuator using the piezoelectric element - Google Patents

Abstract

The present invention relates to a small camera driving apparatus using a piezoelectric element, and more particularly, to a small camera driving apparatus using a piezoelectric element to transfer the lens by driving the lens holder in the vertical direction using the piezoelectric element.

Small camera driving apparatus using the piezoelectric element of the present invention, the base; A lens holder disposed above the base and mounted with a lens and driven in an optical axis direction; A driving unit for driving the lens holder in the optical axis direction; A control part for controlling the driving part, wherein the driving part comprises: a resonator part having one end coupled to the base and the other end contacting an outer circumferential surface of the lens holder; A piezoelectric element mounted on the resonator unit, the piezoelectric element having a first (+) terminal and a second (+) terminal, wherein the control unit has a phase difference of 90 degrees between the first (+) terminal and the second (+) terminal. By applying a voltage having a frequency equal to the resonant frequency of the drive unit, the other end is characterized in that for driving the lens holder in the optical axis direction while the elliptical displacement movement.

Compact camera, drive device, piezoelectric element, resonant frequency

Description

Camera Actuator using the piezoelectric element}

The present invention relates to a small camera driving apparatus using a piezoelectric element, and more particularly, to a small camera driving apparatus using a piezoelectric element to transfer the lens by driving the lens holder in the vertical direction using the piezoelectric element.

A small communication device such as a mobile phone is equipped with a small camera device.

1 is a cross-sectional structural view of a conventional small camera device of the VCM method, Figure 2 is a cross-sectional structural view of the use state of the small camera device shown in FIG.

1 and 2, the small camera apparatus shown in FIGS. 1 and 2 includes a lens group 500 including a plurality of lenses for changing the magnification of a subject or adjusting a focus of a subject, and driving the lens group 500 in an optical axis direction. Supported by the lens holder 550, the fixing part 600, and the fixing part 600 to raise the lens holder 550 to be movable in the optical axis direction, and the lens holder 550 is driven exactly in the optical axis direction. A leaf spring 650 for guiding the guide, an actuator supported by the lens holder 550 to drive the fixing unit 600 in the optical axis direction, and an image for capturing an image of a subject passing through the lens group 500. The sensor 800 and the control unit for controlling the actuator and the image sensor 800.

The leaf spring 650 has a shape in which the width of the leaf spring 650 is narrowed between the portion fixed to the fixing part 600 and the portion fixed to the lens holder 550 to facilitate deformation in the optical axis direction.

Therefore, the leaf spring 650 elastically supports the lens holder 550 to flow in the optical axis direction.

In addition, the leaf spring 650 is fixed to at least four locations of the lens holder 550, and serves as a guide for preventing the lens holder 560 from flowing in a direction orthogonal to the optical axis direction.

On the other hand, the actuator, the magnet 710 is fixed to the fixing part 600, and the lens holder 550 is fixed to the lens holder 550 receives the magnetic flux from the magnet 710 when the power is supplied from the control unit in the optical axis direction It consists of a coil 720 for generating a driving force.

The structure of such an actuator is called a VCM method.

One pair of magnets 710 and one coil 720 are provided at symmetrical portions.

The actuator also has a yoke 730 for circulating the magnetic flux of the magnet 710 efficiently.

In the small camera device having such a configuration, as shown in FIG. 2, when electricity is applied to the coil 720 of the actuator from the controller, the coil 720 moves in the optical axis direction under the influence of the magnetic flux from the magnet 710. To generate an electromagnetic force.

Therefore, the fixing part 600 to which the coil 720 is fixed moves in the optical axis direction.

In this way, the controller raises or lowers the lens group 500 in the optical axis direction so that the image captured by the image sensor 800 becomes clear.

The above-mentioned VCM method works well when the size of the lens holder is small or light in weight, but when the size of the lens holder is large or heavy, there is a problem in that the operation force is not good due to weak moving force.

In addition, the VCM method is not robust, so when a drop test is performed a lot of defective products, the moving distance of the lens holder is short, there is a problem that is difficult to use in the case of a camera using a high pixel sensor.

The present invention provides a compact camera driving apparatus using a piezoelectric element that can be used for a camera equipped with a high pixel sensor because the lens holder works well, is more robust than the VCM method, and has a longer moving distance of the lens holder. There is this.

Small camera driving apparatus using the piezoelectric element of the present invention to achieve the above object, the base; A lens holder disposed above the base and mounted with a lens and driven in an optical axis direction; A driving unit for driving the lens holder in the optical axis direction; A control part for controlling the driving part, wherein the driving part comprises: a resonator part having one end coupled to the base and the other end contacting an outer circumferential surface of the lens holder; A piezoelectric element mounted on the resonator unit, the piezoelectric element having a first (+) terminal and a second (+) terminal, wherein the control unit has a phase difference of 90 degrees between the first (+) terminal and the second (+) terminal. By applying a voltage having a frequency corresponding to the resonant frequency of the drive unit, the other end of the resonator is characterized in that to drive the lens holder in the optical axis direction while the elliptical displacement movement.

The frequency of the voltage applied to the piezoelectric element by the controller is a value between a first resonant frequency at which the other end of the resonator moves up and down and a second resonant frequency at which the other end of the resonator moves left and right.

A fixed shaft protruding from the base in parallel with a moving direction of the lens holder, the driving unit comprising: a resonator unit having one end rotatably coupled to the fixed shaft and the other end contacting an outer circumferential surface of the lens holder; A spring having one end coupled to the resonator unit and the other end coupled to the base to add an elastic force such that the other end of the resonator unit is pressed toward the outer circumferential surface of the lens holder; It includes the piezoelectric element mounted to the resonator.

The spring is made of a torsion spring, and the resonator comprises: a piezoelectric element coupling part on which the piezoelectric element is mounted; A rotary coupling portion formed at one end of the piezoelectric element coupling portion and surrounding the fixed shaft; One end of the piezoelectric element coupling portion is formed separated from the rotary coupling portion, and comprises a spring support portion is coupled to one end of the spring.

The resonator includes: a movable part formed at the other end of the piezoelectric element coupling part to contact an outer circumferential surface of the lens holder; A first connection part connecting an upper portion of the other end of the piezoelectric element coupling part to the movable part; And a second connection part connecting the lower part of the other end of the piezoelectric element coupling part to the movable part, wherein the first connection part and the second connection part are formed to be inclined toward the movable part, and the first connection part and the second connection part are connected to each other. An elastic deformation hole is formed between the piezoelectric element coupling parts.

According to the small camera driving apparatus using the piezoelectric element of the present invention as described above, even if the weight of the lens holder is heavy, it works well, is more robust than the VCM method, and the moving distance of the lens holder is long in the camera equipped with a high pixel sensor Can be used.

Figure 3 is a one-way perspective view of a small camera driving apparatus according to an embodiment of the present invention, Figure 4 is a perspective view of the other direction of the small camera driving apparatus according to an embodiment of the present invention, Figure 5 is a small size according to an embodiment of the present invention One direction exploded perspective view of the camera driving device, Figure 6 is an exploded perspective view of the other direction of the small camera driving device according to an embodiment of the present invention, Figure 7 is a state in which the other end of the resonator vibrating in the vertical direction 8 is a state diagram illustrating a state in which the other end of the resonator vibrates in left and right directions, and FIG. 9 is an elliptic movement of the other end of the resonator in accordance with an embodiment of the present invention. It is a process diagram of the state.

3 to 6, the compact camera driving apparatus of the present invention includes a base 10, a lens holder 20, a driving unit, a control unit, and the like.

The lens holder 20 is disposed above the base 10, and an image sensor (not shown) is disposed below.

A fixed shaft 12 protrudes from the base 10 in parallel with the moving direction of the lens holder 20.

In addition, the upper portion of the base 10, the bearing ball 16 is mounted to the guide portion 14 to facilitate the movement of the lens holder 20 is formed protruding.

The guide portion 14 is formed with a first guide rail groove 15 in which a plurality of bearing balls 16 can slide in the vertical direction.

The lens holder 20 has a lens embedded therein and is driven in the optical axis direction.

At this time, the second peripheral rail groove 25 on which the bearing ball 16 is seated is formed long on the outer circumferential surface of the lens holder 20 in the vertical direction, and the lens holder 20 is the bearing ball 16. It is connected to the guide portion 14 through).

Therefore, when the lens holder 20 is moved in the vertical direction, the lens holder 20 by the bearing ball 16 disposed between the first guide rail groove 15 and the second guide rail groove 25. ) Can be moved in the vertical direction more smoothly.

In addition, a friction part 27 is formed on the outer circumferential surface of the lens holder 20 to contact the driving part.

The driving unit serves to drive the lens holder 20 by pushing or pulling in the optical axis direction.

The drive unit includes a resonator unit 30, a piezoelectric element 40, and a spring 50.

One end of the resonator 30 is rotatably coupled to the fixed shaft 12 in detail, and the other end of the resonator 30 contacts the friction part 27 in detail on the outer circumferential surface of the lens holder 20. .

The resonator part 30 includes a piezoelectric element coupling part 31, a rotation coupling part 32, a spring support part 33, a movable part 34, a first connection part 35, and a second connection part. 36, elastic deformation holes 37, and the like.

The piezoelectric element coupling portion 31 has a flat plate shape, and the piezoelectric element 40 is mounted on one surface thereof.

The rotary coupling part 32 and the spring support part 33 are separated from one end of the piezoelectric element coupling part 31 in the vertical direction.

The rotary coupling portion 32 is formed to surround the fixed shaft 12 on one end of the piezoelectric element coupling portion 31, to couple the resonator portion 30 to the fixed shaft 12, When the resonator unit 30 rotates, the resonator unit 30 forms the center of rotation of the resonator unit 30 together with the fixed shaft 12.

The spring support part 33 is formed to be separated from the rotary coupling part 32 at one lower end of the piezoelectric element coupling part 31, and one end of the spring 50 is coupled thereto.

The movable part 34 is formed at the other end of the piezoelectric element coupling part 31 to contact the friction part 27 in detail on the outer circumferential surface of the lens holder 20.

The width of the movable part 34 is smaller than the width of the piezoelectric element coupling part 31.

As described later, when the resonator 30 flows due to the voltage applied by the controller, the width of the movable part 34 is reduced, so that a force is concentrated on the movable part 34 so that the displacement motion is greater. This is to make it work well.

The first connecting portion 35 connects the upper portion of the other end of the piezoelectric element coupling portion 31 and the movable portion 34, and the second connecting portion 36 is connected to the lower end of the other end of the piezoelectric element coupling portion 31. The movable part 34 is connected.

At this time, the first connecting portion 35 and the second connecting portion 36 are formed to be inclined toward the movable portion 34, respectively.

The elastic deformation hole 37 is formed between the first connection part 35, the second connection part 36, and the piezoelectric element coupling part 31.

That is, the first connection part 35 and the second connection part 36 are formed to be inclined toward the movable part 34, and the elastic deformation hole 37 is formed in a substantially triangular or trapezoidal shape.

As described above, the first connecting portion 35 and the second connecting portion 36 may flow better when the resonator portion 30 flows by the elastic deformation hole 37, so that the first connecting portion 35 ) And the movable part 34 connected to the second connection part 36 can be better flow.

The piezoelectric element 40 is deformed by applying a voltage, and serves to cause the resonator unit 30 to be initially vibrated, and thus the resonator unit 30 is mounted on the piezoelectric element coupling unit 31 in detail. And a first (+) terminal 41 and a second (+) terminal 42.

That is, the first (+) terminal 41 and the second (+) terminal 42 are disposed on one surface of the piezoelectric element 40, and the first (+) terminal 41 and the first surface on the other surface thereof. One (-) terminal 43 in contact with the 2 (+) terminal 42 is disposed.

As described above, in the present embodiment, one piezoelectric element 40 having two (+) terminals and one (-) terminal 43 is used. However, unlike the present embodiment, one (+) terminal and one each is used. Two piezoelectric elements 40 having four (-) terminals 43 may be used.

The spring 50 has one end coupled to the resonator 30 in detail, the spring support 33, and the other end coupled to the base 10, and the other end of the resonator 30 is the lens holder ( An elastic force is added to press in the direction of the outer circumferential surface of 20).

To this end, the spring 50 is preferably made of a torsion spring.

In this embodiment, the spring 50 is mounted in an expanded state to apply a force to the spring support 33.

The control unit controls the driving unit, and in detail, controls the voltage applied to the piezoelectric element 40 so that the driving unit is driven to move the lens holder 20.

The control unit applies a voltage having a phase difference of 90 degrees to the first (+) terminal 41 and the second (+) terminal 42 and having a frequency corresponding to the resonance frequency of the driving unit, thereby resonating the resonance. The movable part 34 located at the other end of the part 30 drives the lens holder 20 in the optical axis direction while performing an elliptical displacement motion.

In this case, the frequency of the voltage applied to the piezoelectric element 40 by the control unit is between the first resonant frequency of the other end of the resonator 30 moving up and down, and the second resonant frequency of the other end of the resonator moving left and right Value.

By setting the frequency of the voltage applied to the piezoelectric element 40 as the value between the first resonant frequency and the second resonator as described above, the other end of the resonator 30 combines the vertical motion and the left and right motion to perform an elliptic motion. .

Hereinafter, an operation process of the present invention having the above-described configuration will be described.

The controller applies a voltage having a phase difference of 90 degrees to the first (+) terminal 41 and the second (+) terminal 42 of the piezoelectric element 40.

That is, the phases of the voltages applied to the first (+) terminal 41 and the second (+) terminal 42 have a difference of 90 degrees.

In this case, the frequency of the applied voltage is a frequency corresponding to the resonance frequency of the drive unit.

When a voltage having a phase difference of 90 degrees is applied to the first (+) terminal 41 and the second (+) terminal 42 of the piezoelectric element 40, the piezoelectric element 40 is contracted and expanded. Thus, the resonator 30 to which the piezoelectric element 40 is coupled also flows.

At this time, since the frequency of the applied voltage coincides with the resonant frequency of the driving unit, the driving unit can be largely flown in detail with the driving force with a small force.

In more detail, as shown in FIG. 7, the other end of the resonator unit 30 moves in the vertical direction by the first resonant frequency.

As shown in FIG. 8, the other end of the resonator unit 30 moves in the left and right directions by the second resonant frequency.

When the first resonant frequency for vibrating the other end of the resonator 30 in the vertical direction is 53 kHz, and the second resonant frequency for vibrating the other end of the resonator 30 in the left and right direction is 55 kHz, the control unit uses the piezoelectric element. A resonant frequency of 54 kHz, which is a value between the first resonant frequency and the second resonant frequency, is applied to the element 40.

Then, as shown in FIG. 9, the other end of the resonator 30 is combined with the vibration mode in the vertical direction and the vibration mode in the left and right directions to perform an elliptic motion.

When the above voltage is applied, as shown in FIG. 9, the movable part 34 is elliptical.

At this time, by forming the elastic deformation hole 37 between the first connection portion 35 and the second connection portion 36, the flow amount of the first connection portion 35 and the second connection portion 36 can be increased. In addition, the movable part 34 connected to the first connection part 35 and the second connection part 36 may be made to flow larger.

As the movable part 34 performs an elliptical displacement movement, the movable part 34 pushes the lens holder 20 upward or downward to move the lens holder 20 in the optical axis direction. Make sure

As the movable part 34 performs an elliptic motion, the resonator part 30 rotates about the fixed shaft 12 and the rotary coupling part 32.

In addition, the spring 50 is connected to the spring support 33 formed at one end of the resonator 30 so as to push the spring support 33, the other end of the resonator 30 by the lever principle The movable portion 34 formed in the may be in close contact with the lens holder 20.

As a result, the movable part 34 is always in contact with the outer circumferential surface of the lens holder 20 to move the lens holder 20 in the vertical direction.

At this time, the spring 50 is mounted in a compressed or inflated state, and the movable part 34 formed at the other end of the other end of the resonator 30 by adding an elastic force to the spring support 33 is the lens holder ( 20) to be strongly pressed toward the outer circumferential surface thereof.

The compact camera driving apparatus using the piezoelectric element of the present invention is not limited to the above-described embodiment, and may be variously modified and implemented within the range in which the technical idea of the present invention is permitted.

1 is a cross-sectional structure diagram of a conventional small camera device of the VCM method,

2 is a cross-sectional structural view of the state of use of the small camera device shown in FIG.

3 is a one-way perspective view of a compact camera driving apparatus according to an embodiment of the present invention;

4 is another perspective view of a compact camera driving apparatus according to an embodiment of the present invention;

5 is an exploded perspective view in one direction of a small camera driving apparatus according to an embodiment of the present invention;

6 is an exploded perspective view of another direction of the compact camera driving apparatus according to the embodiment of the present invention;

7 is a state diagram showing a state in which the other end of the resonator vibrates in the vertical direction according to an embodiment of the present invention;

8 is a state diagram illustrating a state in which the other end of the resonator vibrates in left and right directions according to an embodiment of the present invention;

9 is a process diagram of the other end of the resonator according to an embodiment of the present invention to perform an elliptic motion,

<Description of the symbols for the main parts of the drawings>

10: base, 12: fixed shaft, 14: guide portion, 15: first guide rail groove, 16: bearing ball, 20: lens holder, 25: second guide rail groove, 27: friction portion, 30: resonator portion, 31: piezoelectric element coupling portion, 32: rotary coupling portion, 33: spring support portion, 34: movable portion, 35: first connection portion, 36: second connection portion, 37: elastic deformation hole, 40: piezoelectric element, 41: first ( +) Terminal, 42: second (+) terminal, 43: (-) terminal, 50: spring,

Claims (5)

A base; A lens holder disposed above the base and mounted with a lens and driven in an optical axis direction; A driving unit for driving the lens holder in the optical axis direction; Consists of a control unit for controlling the drive unit, The driving unit includes: A resonator unit having one end coupled to the base and the other end contacting an outer circumferential surface of the lens holder; A piezoelectric element mounted on the resonator and having a first (+) terminal and a second (+) terminal, The control unit, A voltage having a phase difference of 90 degrees to the first (+) terminal and the second (+) terminal and having a frequency corresponding to the resonance frequency of the driving unit is applied, so that the other end of the resonance unit is elliptical displacement by the piezoelectric element. While driving the lens holder in the optical axis direction by the friction caused by the contact with the outer peripheral surface of the lens holder while vibrating, The frequency of the voltage applied to the piezoelectric element by the controller is a value between a first resonant frequency of moving the other end of the resonator part up and down, and a second resonant frequency of moving the other end of the resonator part left and right, The base has a fixed shaft protruding in parallel with the movement direction of the lens holder, The driving unit includes: One end of which is rotatably coupled to the fixed shaft, and the other end of which is in contact with an outer circumferential surface of the lens holder; A spring having one end coupled to the resonator unit and the other end coupled to the base to add an elastic force such that the other end of the resonator unit is pressed toward the outer circumferential surface of the lens holder; Including the piezoelectric element mounted to the resonator, The spring is made of a torsion spring, The resonator unit, A piezoelectric element coupling part on which the piezoelectric element is mounted; A rotary coupling portion formed at one end of the piezoelectric element coupling portion and surrounding the fixed shaft; Small piezoelectric element driving device using a piezoelectric element, characterized in that the piezoelectric element is separated from the rotary coupling portion at one end, and comprises a spring support to which one end of the spring is coupled. delete The method of claim 1, The upper portion of the base is a bearing ball is mounted is formed to protrude the guide portion to facilitate the movement of the lens holder, The guide portion is formed with a first guide rail groove that can slide a plurality of bearing balls in the vertical direction, The second guide rail groove in which the bearing ball is seated is formed long on the outer circumferential surface of the lens holder, and the lens holder is connected to the guide part through the bearing ball. Camera drive. delete The method according to claim 1 or 3, The resonator unit, A movable part formed at the other end of the piezoelectric element coupling part to contact an outer circumferential surface of the lens holder; A first connection part connecting an upper portion of the other end of the piezoelectric element coupling part to the movable part; Further comprising a second connecting portion for connecting the lower portion of the other end and the movable portion of the piezoelectric element coupling portion, The first connection portion and the second connection portion is formed to be inclined toward the movable portion, Small camera driving apparatus using a piezoelectric element, characterized in that the elastic deformation hole is formed between the first connection portion, the second connection portion and the piezoelectric element coupling portion.

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