KR101068889B1 - Moving method of camera lens-holder - Google Patents

Abstract

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

In the method for driving a small camera lens holder of the present invention, the lens holder for driving a lens holder for a small camera lens in the vertical direction using a drive body equipped with a piezoelectric element, the driving body is A movable part is formed in contact with a lens holder and drives the lens holder in an up and down direction by performing an elliptic trajectory motion by the expansion and contraction movement of the piezoelectric element. The movable part has a first specific frequency applied to the piezoelectric element. It has a curved form only once in one of the up and down directions by the voltage, and repeatedly vibrates in the up and down direction as time passes, and in each of the left and right directions by the voltage of the second specific frequency applied to the piezoelectric element. Repeatedly vibrating in the left and right directions over time while having a curved shape, the piezoelectric element having the first feature Is applied to the optimum voltage at a specific frequency between the frequency and the second specific frequency, characterized in that that the movement trajectory of the movable part elliptical shape.

Compact camera lens holder, driving method, piezoelectric element

Description

Driving method of small camera lens holder {Moving method of camera lens-holder}

The present invention relates to a method of driving a small camera lens holder, and more particularly, to a method of driving a small camera lens holder to drive the lens holder in the vertical direction by using a 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. It consists of a sensor 800, a 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 control unit, the coil 720 moves in the optical axis direction under the influence of the magnetic flux emitted 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 works well even if the weight of the lens holder is heavy, is more robust than the VCM method, and the moving distance of the lens holder is long, the object of the present invention is to provide a method for driving a small camera lens holder that can be used in a camera equipped with a high-pixel sensor. have.

In order to achieve the above object, a method of driving a small camera lens holder of the present invention is a method of driving a lens holder for a small camera lens holder for driving a lens holder incorporating a lens in a vertical direction using a driving body equipped with a piezoelectric element. And a movable part in contact with the lens holder and driving the lens holder in an up-down direction by performing an elliptic trajectory motion by the elastic movement of the piezoelectric element, wherein the movable part is applied to the piezoelectric element. Due to the voltage of the first specific frequency to be bent only one time in any one of the up and down direction and repeatedly vibrating in the up and down direction over time, by the voltage of the second specific frequency applied to the piezoelectric element Once in each of the left and right direction has a curved form and vibrates repeatedly in the left and right direction over time, Group piezoelectric elements is characterized in that to the first specific frequency and a second voltage is applied to a particular frequency of the optimum between certain frequency, it locus motion of the movable portion an oval shape.

The optimum specific frequency is a frequency having a value 1/2 of the sum of the first specific frequency and the second specific frequency.

The difference between the first specific frequency and the second specific frequency is preferably 3 kHz or less.

The piezoelectric element includes a first (+) terminal and a second (+) terminal, and a voltage having a phase difference of 90 degrees is applied to the first (+) terminal and the second (+) terminal.

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

3 is a perspective view of a small camera driving apparatus according to an embodiment of the present invention, Figure 4 is a plan view of a small camera driving apparatus according to an embodiment of the present invention, Figure 5 is a small camera driving apparatus according to an embodiment of the present invention 6 is a perspective view of a driving body according to an exemplary embodiment of the present invention, and FIG. 7 is a state diagram illustrating a state in which the other end of the resonator vibrates in an up and down direction according to an exemplary embodiment of the present invention. 9 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 a process diagram of a state in which the other end of the resonator vibrates in an elliptic shape according to an embodiment of the present invention. 10 is a plan view of a driving body having various structures according to an embodiment of the present invention.

3 to 5, the compact camera driving apparatus includes a base member 10, a lens holder 20, a driving body 30, a leaf spring 40, and a movement guide member 50. ), A flexible circuit board 45, and a control unit.

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

The base member 10 is formed with a side portion 11 and a fixed shaft 12 parallel to the moving direction of the lens holder 20.

The lens holder 20 includes a lens (not shown) therein and is driven by moving in the optical axis direction, that is, the vertical direction.

On the outer circumferential surface of the lens holder 20, a friction part 21 for contacting the driving body 30 is formed in the vertical direction.

In addition, the movement guide member 50 is disposed between the side portion 11 of the base member 10 and the lens holder 20 so as to smoothly move the lens holder 20 up and down. .

The movement guide member 50 includes a retainer 51 disposed between the side portion 11 and the lens holder 20 and a ball member 52 rotatably inserted into the retainer 51.

The retainer 51 is not in contact with the side portion 11 and the lens holder 20, and the ball member 52 is in contact with the side portion 11 and the lens holder 20.

To this end, the diameter of the ball member 52 is larger than the thickness of the retainer 51.

In addition, the side grooves 11 and the lens holder 20 has rail grooves 13 and 23 formed on the ball members 52 to move in the vertical direction.

When the lens holder 20 moves, the retainer 51 moves only about half of the moving distance of the lens holder 20.

In addition, one of the base member 10 or the lens holder 20 has a guide protrusion 14 formed in the moving direction of the lens holder 20, and the guide protrusion 14 is inserted into the other one. Guide grooves 22 are formed, the lens holder 20 is rotated in the horizontal direction to prevent the flow.

In the present embodiment, the guide protrusions 14 are formed in the base member 10 in the vertical direction, and the guide grooves 22 are formed in the lens holder 20 in the vertical direction.

The driving member 30 serves to push or pull the lens holder 20 in the optical axis direction, that is, in the vertical direction.

As shown in FIGS. 5 and 6, the driver 30 includes a resonator 31 and a piezoelectric element 39.

One end of the resonator part 31 is coupled to the base member 10, in detail, the fixed shaft 12, and the other end of the resonator part 31 is in contact with the frictional part 21 in detail on the outer circumferential surface of the lens holder 20. .

The resonator part 31 includes a piezoelectric element coupling part 32, a movable part 33, a coupling protrusion 34, and a friction member 35.

The piezoelectric element coupling part 32 has a flat plate shape, and the piezoelectric element 39 is mounted on one surface thereof.

The movable part 33 protrudes from the other end of the piezoelectric element coupling part 32 to perform an elliptical displacement motion by the piezoelectric element 39.

One end of the movable part 33 is connected to the piezoelectric element coupling part 32, the other end of the movable part 33 is free, and the other end of the movable member 33 is coupled to the friction member 35.

The width of the movable part 33 is smaller than the width of the piezoelectric element coupling part 32.

In addition, the movable portion 33 is formed with a hole-shaped adjusting hole 37 for adjusting the displacement movement trajectory of the movable portion 33.

As shown in FIG. 10, the adjustment hole 37 may be formed at various positions in the movable part 33, which will be described in detail later.

The coupling protrusion 34 is formed in plural and protrudes from one end of the piezoelectric element coupling part 32 so as to be spaced apart from each other, and serves to couple the resonance part 31 to the fixed shaft 12. .

In order to allow the fixed shaft 12 to be inserted between the plurality of coupling protrusions 34, the distance between the ends of the coupling protrusions 34 is smaller than the diameter of the fixed shaft 12.

That is, when the coupling protrusion 34 is fitted to the fixed shaft 12, the ends of the coupling protrusion 34 extend in a direction away from each other while contacting the fixed shaft 12, and then contract again. One end of the resonator 31 is coupled to the fixed shaft 12 while surrounding the shaft 12.

The friction member 35 is coupled to the other end of the movable part 33 and in contact with the frictional part 21 mounted to the lens holder 20 during the movement of the movable part 33 to the lens holder 20. Transfer the force to move up and down.

The piezoelectric element 39 is mounted on the resonator unit 31 in detail, and the piezoelectric element coupling unit 32 receives the current from the flexible circuit board 45 and deforms it to operate the resonator unit 31. It plays a role, and comprises a first (+) terminal 39a and a second (+) terminal 39b.

In the piezoelectric element 39, the first (+) terminal 39a and the second (+) terminal 39b are disposed on one surface, and one (-) terminal 39c is disposed on the other surface.

The first (+) terminal 39a and the second (+) terminal 39b are mounted in parallel with each other along the longitudinal direction of the resonator unit 31.

The piezoelectric element 39 is applied with a voltage having a phase difference of 90 degrees to the first (+) terminal 39a and the second (+) terminal 39b, so that the piezoelectric element 39 causes the resonance unit. Stretched in the longitudinal direction of the (31) to drive the resonator (31).

As described above, in this embodiment, one piezoelectric element 39 having two (+) terminals and one (-) terminal 39c is used. However, unlike the present embodiment, each of the one (+) terminals Two piezoelectric elements 39 having one negative terminal 39c may be used.

The leaf spring 40 serves to press the driving body 30 in the direction of the outer circumferential surface of the lens holder 20.

To this end, the leaf spring 40 is coupled to the side portion 11 of the base member 10 in a hook manner while surrounding the outside of the drive body 30.

The flexible circuit board 45 is disposed between the driving member 30 and the leaf spring 40 to supply current to the piezoelectric element 39.

One surface of the flexible circuit board 45 is in contact with the piezoelectric element 39, and the other surface of the flexible circuit board 45 is in contact with the plate spring 40.

In addition, the flexible circuit board 45 is coupled to the sponge 46 in the direction of the plate spring 40 so that the plate spring 40 and the flexible circuit board 45 is always in contact with each other.

As a result, the leaf spring 40, the flexible circuit board 45, and the driving body 30 may be always in contact with each other, so that the pressing force of the leaf spring 40 is always transmitted to the driving body 30. Can be.

The controller controls the driving body 30, and in detail, controls the voltage applied to the piezoelectric element 39 so that the driving body 30 is driven to move the lens holder 20. It plays a role.

The control unit has a voltage having a phase difference of 90 degrees between the first (+) terminal 39a and the second (+) terminal 39b, respectively, and having a frequency corresponding to the resonance frequency of the driver 30. It is applied to the piezoelectric element 39 so that the movable part 33 located at the other end of the resonator 31 drives the lens holder 20 in the optical axis direction while performing an elliptical displacement motion.

FIG. 7 illustrates the movement of the movable portion 33 as viewed in the Y-axis direction shown in FIG. 5, and FIG. 8 illustrates the movement of the movable portion 33 as viewed in the Z-axis direction shown in FIG. 5, and FIG. 9. FIG. 5 illustrates the movement of the movable part 33 as viewed in the X-axis direction shown in FIG. 5.

As shown in FIG. 7, the movable part 33 has a bent shape only once in one of the up and down directions by the voltage of the first specific frequency applied to the piezoelectric element 39. It vibrates repeatedly in the vertical direction.

As shown in FIG. 8, the movable part 33 has a curved shape once in each of the left and right directions by a voltage of the second specific frequency applied to the piezoelectric element 39. It vibrates repeatedly from side to side.

That is, the first specific frequency is curved in an arc shape, and the second specific frequency is curved in a wavy sinusoidal shape.

The controller is configured to apply a voltage of an optimum specific frequency between the first specific frequency and the second specific frequency to the piezoelectric element 39, so that the movable portion 33 moves in an elliptic shape as shown in FIG. Do it.

The optimum specific frequency is a frequency having a value 1/2 of the sum of the first specific frequency and the second specific frequency, and the difference between the first specific frequency and the second specific frequency is preferably 3 kHz or less.

As described above, by applying a voltage having a phase difference of 90 degrees to the piezoelectric element 39 and having the optimum specific frequency, the movable part 33 is moved up and down by a first specific frequency (Fig. 7), The left and right movements by two specific frequencies (Fig. 8) are combined to make an elliptic movement (Fig. 9).

10 shows various shapes of the drive body 30 of the present invention.

As shown in FIGS. 10 (b) and 10 (c), when the adjusting hole 37 is formed in a closed curve shape, that is, inside the movable part 33, the adjusting hole 37 is formed of the movable part 33. It should be formed in the center of the width.

That is, the symmetry in both directions of the width of the movable portion 33 with respect to the adjusting hole (37).

And, as shown in Figure 10 (a), (d), (e), when the adjustment hole 37 is formed to open the shape of the curved line, that is, the outer surface of the movable portion 33, the adjustment hole 37 is formed to be symmetrical on both sides of the movable portion 33 in the width direction.

As shown in FIG. 10A, when the adjusting hole 37 is formed in the shape of an open curve contacting the piezoelectric element coupling portion 32 at one end of the movable portion 33, the movable portion 33 is formed. When the displacement motion in the width direction it can be made to be more bent the movable portion 33.

As shown in FIG. 10B, when the adjusting hole 37 is formed in a closed curve shape, the adjusting hole 37 is formed at the center of the width of the movable part 33, so that the movable part 33 is formed. If you exercise vertically or horizontally, you can exercise in a balanced manner without eccentricity.

As shown in FIG. 10 (c), when the extension part 38 is widened at one end of the movable part 33 and connected to the piezoelectric element coupling part 32, the piezoelectric element 39 is formed. The force generated at may be better transmitted to the movable portion 33 through the expansion portion 38.

As shown in FIG. 10 (d), the adjustment hole 37 is formed symmetrically on both sides of the width direction of the movable part 33 in an open curve shape between one end and the other end of the movable part 33. It may be.

As shown in FIG. 10E, the adjustment hole 37 may be formed between one end and the other end of the movable part 33 and at one end of the movable part 33.

In this case, the size of the adjusting hole 37 is smaller than the size of the adjusting hole 37 shown in FIGS. 10 (a) and 10 (d).

In addition, as shown in FIG. 10 (f), the adjustment hole 37 may not be formed in the movable part 33.

10 (a) to 10 (e), when the adjusting hole 37 is formed, the first specific frequency and the second specific frequency are adjacent to each other, as shown in FIG. 10 (f). When the adjustment hole 37 is not formed, the distance between the first specific frequency and the second specific frequency is farther than that when the adjustment hole 37 is formed.

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 39a and the second (+) terminal 39b of the piezoelectric element 39.

That is, the phase of the voltage applied to the first (+) terminal 39a and the second (+) terminal 39b has a difference of 90 degrees.

In this case, the frequency of the applied voltage is a frequency corresponding to the resonant frequency of the driver 30.

When a voltage having a phase difference of 90 degrees is applied to the first (+) terminal 39a and the second (+) terminal 39b of the piezoelectric element 39, the piezoelectric element 39 performs contraction and expansion movement. Thus, the resonator 31 to which the piezoelectric element 39 is coupled also flows.

In this case, since the frequency of the applied voltage coincides with the resonant frequency of the driving unit, the resonating unit 31 may be largely flown in detail with the driving unit with a small force.

In more detail, as shown in FIG. 7, the movable part 33 formed at the other end of the resonator part 31 is moved up and down by a first specific frequency.

At this time, the movable part 33 repeatedly vibrates in the vertical direction over time while having a curved form only once in one of the vertical directions.

As shown in FIG. 8, the movable part 33 moves in the left and right directions by the second specific frequency.

At this time, the movable part 33 has a curved form once each in both the left and right directions (up and down direction in Fig. 8) of the lens holder 20, and repeatedly vibrates in the left and right directions over time.

When the first specific frequency for oscillating the movable part 33 in a vertical direction is bent 311 kHz and the second specific frequency for oscillating the movable part 33 in a left and right direction is 313 kHz, in the control unit, An optimal specific frequency of 312 kHz, which is an average value of the sum of the first specific frequency and the second specific frequency, is applied to the piezoelectric element 39.

Then, as shown in FIG. 9, the movable part 33 is an elliptic motion by combining the first bent vibration mode in the vertical direction and the two bent vibration modes in the left and right directions.

When the above voltage is applied, as shown in FIG. 9, the friction member 35 to which the other end of the movable part 33 is coupled has an elliptic motion.

On the other hand, when the difference between the first specific frequency and the second specific frequency is large, the difference between the optimum specific frequency, the first specific frequency and the second specific frequency is turned on to provide a voltage having the optimum specific frequency to the movable unit 33. Even if it is applied, the movable part 33 does not perform an elliptic motion.

In this case, by using the adjusting hole 37, the movable part 33 is oscillated to be bent once in the vertical direction and the movable part 33 is oscillated to be bent twice in the left and right directions. The second specific frequency so as to have a value adjacent to each other.

As the movable part 33 performs an elliptical displacement movement, the friction member 35 coupled to the movable part 33 comes into contact with the frictional part 21 mounted to the lens holder 20 while the lens is in contact with the lens. The holder 20 is pushed up or pushed down to allow the lens holder 20 to move in the optical axis direction.

In addition, since the leaf spring 40 pushes the driving member 30 in the direction of the lens holder 20, the movable part 33 having the friction member 35 is provided with the frictional part 21. It may be in close contact with the lens holder 20.

As a result, the movable part 33 is always in contact with the outer circumferential surface of the lens holder 20 to move the lens holder 20 in the vertical direction.

The method of driving the compact camera lens holder of the present invention is not limited to the above-described embodiment, and may be modified and implemented in various ways within the scope of the technical idea of the present invention.

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

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

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

6 is a perspective view of a driving body according to an 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 a state in which the other end of the resonator in accordance with an embodiment of the present invention performs an elliptic trajectory motion;

10 is a plan view of a driving body having a variety of structures according to an embodiment of the present invention,

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

10: base member, 11: side part, 12: fixed shaft, 13: rail groove, 14: guide protrusion, 20: lens holder, 21: frictional part, 22: guide groove, 23: rail groove, 30: driving body, 31: resonator portion, 32: piezoelectric element coupling portion, 33: movable portion, 34: coupling protrusion, 35: friction member, 37: adjusting hole, 38: extension portion, 39: piezoelectric element, 39a: first (+) terminal, 39b: 2nd (+) terminal, 39c: (-) terminal, 40: leaf spring, 45: flexible circuit board, 46: sponge, 50: moving guide member, 51: retainer, 52: ball member,

Claims (4)

In a driving method of a lens holder for a small camera for driving a lens holder incorporating a lens in a vertical direction by using a driving body equipped with a piezoelectric element, The driving body is provided with a movable part which is in contact with the lens holder and drives the lens holder in an up and down direction by performing an elliptic trajectory movement by the stretching movement of the piezoelectric element. The movable part, It vibrates repeatedly in the vertical direction as time goes by having a curved form only once in one of the vertical directions by the voltage of the first specific frequency applied to the piezoelectric element, While oscillating repeatedly in the left and right direction as time passes by the voltage of the second specific frequency applied to the piezoelectric element, each having a curved form once in each of the left and right directions, The piezoelectric element is applied with a voltage of an optimum specific frequency between the first specific frequency and the second specific frequency so that the movable portion performs an elliptic locus motion, The optimal specific frequency is a frequency having a value 1/2 of the sum of the first specific frequency and the second specific frequency, The difference between the first specific frequency and the second specific frequency is less than 3Khz, The piezoelectric element includes a first (+) terminal and a second (+) terminal, And a voltage having a phase difference of 90 degrees between the first (+) terminal and the second (+) terminal. delete delete delete

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