KR20100106715A - Multi degree of freedom piezoelectric linear actuator and manipulation method thereof and device for adjusting the focus - Google Patents

Abstract

PURPOSE: A multi degree of freedom piezoelectric linear actuator, a manipulation method thereof, and a device for adjusting focus are provided to obtain a plurality of degree of freedoms by freely linearly driving a plurality of movers. CONSTITUTION: A frame(110) supports one side of a piezoelectric actuator(120). A driving shaft(130) has a long bar of a circular cross-section. The mover unit is comprised of a first mover(141) and a second mover(142). A driver circuit(150) applies a driving voltage having a predetermined waveform to the piezoelectric actuator. A controller(160) controls the driver circuit.

Description

Multi-degree of freedom piezoelectric linear actuator, its driving method and focus control device using the same

The present invention relates to a piezoelectric linear driver, and more particularly, has a plurality of movers, and utilizes the frictional and inertial forces of the mover generated by inflating or contracting the piezoelectric body with a driving voltage having a predetermined waveform. The present invention relates to a piezoelectric linear driver having multiple degrees of freedom that can be driven or driven simultaneously, a driving method thereof, and a focus adjusting device using the same.

Current electronic products are being miniaturized and multifunctional due to the demand of consumers for ease of portability. Miniature drivers are required for the operation of these portable electronics. For example, a small driver is used for the camera's automatic focusing, image stabilization, and vibration functions in mobile phones or game machines.

On the other hand, one of the biggest factors that determine the performance of the robot can be referred to as the drive unit. High-performance compact drivers are required for delicate work that mimics human hand movements or for tasks that require flexible motion, such as catching falling eggs.

A typical representative small driver is a stepping motor. The motor of the electromagnetic system that can be mounted for driving a camera lens has a problem in that volume and weight are increased because a reduction gear and a cam are used to convert the fast rotation into a linear motion. In addition, there is a disadvantage that the backlash occurs during forward rotation or reverse rotation, so that an error occurs easily and power consumption is high due to high heat.

As a solution of the above problems, there is a linear driver using a piezoelectric element (piezoelectric element). Such a piezoelectric linear driver is also called an ultrasonic motor and is a driving source that does not require a magnet or a winding. Piezoelectric linear actuators generate high driving speed at low speed and are not affected by the magnetic field. In addition, a drive transmission element such as a gear is rarely used, so the structure thereof is simple. In addition, it can drive with low noise, there is an advantage that can be precise position control up to nanometers.

1 is a schematic perspective view of a camera lens driving apparatus to which a piezoelectric linear driver according to the prior art is applied. The piezoelectric linear driver 1 according to the related art is composed of a frame 10, a piezoelectric body 20, a drive shaft 30, a mover 40, a drive circuit 50, and a controller 60. The piezoelectric body 20 is configured by stacking plate-shaped piezoelectric elements, and one end of the piezoelectric body 20 is fixed to the frame 100. In addition, the driving shaft 30 is vertically fixed to the other end surface of the piezoelectric body 20. Then, one mover 40 is fitted to the drive shaft 30, and the drive circuit 50 and the controller 60 are electrically connected to the piezoelectric body 20.

The operation principle of the piezoelectric linear driver according to the prior art will be described with reference to FIGS. 1 to 3. The driving circuit 50 connected to the control unit 60 applies a driving voltage having the waveform 70 as shown in FIG. 2 to the piezoelectric body 20. The drive voltage in the form of a pulse has a waveform 70 consisting of a gently inclined rising portion 72 and a sharply inclined falling portion 74.

By the driving voltage, the piezoelectric body 20 is expanded or contracted. When the positive driving voltage indicated by the solid line in FIG. 2 is applied to the piezoelectric body 20, the piezoelectric body 20 is expanded by the rising portion 72 of the driving voltage, and is lowered by the falling portion 74. Return to, ie shrink. Then, when a negative driving voltage indicated by a dotted line is applied to the piezoelectric body 20, the piezoelectric body 20 contracts by the lower portion 72 "of the driving voltage, and is raised by the rising portion 74". Return, ie expand. In this way, the drive shaft 30 is driven by the piezoelectric body 20 that expands or contracts. At this time, the drive displacement of the drive shaft 30 has a shape substantially the same as the waveform 70 of the drive voltage shown in FIG.

On the other hand, the piezoelectric body 20 expands in the direction of the arrow as shown in FIG. At this time, the friction force f is generated in the driving direction of the drive shaft 30 between the mover 40 and the drive shaft 30. In addition, since the drive shaft 30 is accelerated and driven, the mover 40 has the inertia force (ma _E ; m is the mass of the mover, a _E is the acceleration of expansion of the piezoelectric body) in the opposite direction to the friction force f, according to the law of inertia. Is generated. At this time, since the gently rising portion 72 of the driving voltage decreases the acceleration a _E , the friction force f is greater than the inertia force ma _E of the mover 40. Therefore, as shown in FIG. 3B, the mover 40 moves together with the drive shaft 30.

Meanwhile, as shown in FIG. 3B, the piezoelectric body 20 returns to the direction of the arrow, that is, shrinks due to the abruptly inclined lower portion 74 of the driving voltage in FIG. 2. The friction force f is generated between the mover 40 and the drive shaft 30 in the driving direction of the drive shaft 30. At this time, since the descending portion 74 of the driving voltage is inclined sharply, the acceleration a _S (contraction acceleration of the piezoelectric member) increases, so the inertial force ma _S of the mover 40 is greater than the friction force f. Therefore, as shown in FIG. 3C, the mover 40 remains in place and only the drive shaft 30 is returned.

As a result, the mover 40 is advanced by the length of S shown in FIG. 3 by one unit waveform 70. On the other hand, when the driving circuit 50 applies a negative driving voltage to the piezoelectric body 20 by the controller 60, the driving circuit 50 retreats by S length. Therefore, since the above-described operation is repeated by the driving voltage in the form of a pulse, the mover 40 can linearly move.

The conventional piezoelectric linear driver described above is applied to a camera lens driving apparatus 1 or the like as shown in FIG. In the camera lens driving apparatus 1, the microlens 80 is fixed to the mover 40 and linearly moves along the mover 40. Since the camera lens driving device 1 includes only one mover 40, the camera lens driving device 1 has 1 degree of freedom. Therefore, two or more camera lens driving apparatuses 1 are required for focusing, magnification, and the like. That is, the camera lens driving device 1 has a complicated structure in which the camera lens driving device 1 is arranged in series or in parallel. This type of design has a problem that it is difficult to miniaturize the electronics, such as to increase the volume and weight of the driver. In addition, there are problems that many restrictions are followed in designing a product.

The present invention is to solve the above problems, an object of the present invention is to provide a piezoelectric linear driver having a plurality of degrees of freedom that can be driven at the same time, or at the same time freely equipped with a plurality of movers. .

Piezoelectric linear actuator having a multiple degree of freedom according to the present invention to achieve the above object frame; A piezoelectric body having one end fixed to the frame; A driving shaft having one end fixed to the other end surface of the piezoelectric body; A plurality of movers fitted to the drive shaft with different frictional forces with the drive shaft; A driving circuit for applying a driving voltage having a predetermined waveform to the piezoelectric body; And a control unit for controlling the driving circuit, wherein at least one of the plurality of movers is moved according to the waveform of the driving voltage. At this time, the mover has different masses.

On the other hand, the linear actuator having multiple degrees of freedom according to the first embodiment of the present invention is characterized in that the frictional force of the first mover having two movers, the relatively small mass is greater than the frictional force of the second mover having a relatively large mass . The driving circuit applies a driving voltage having a first waveform for moving only the first mover, a second waveform for moving the first and second movers, or a third waveform for moving only the second mover to the piezoelectric body. In this case, the first waveform includes: a first rising part generating an inertial force of the first mover smaller than the friction force of the first mover and an inertial force of the second mover greater than the friction force of the second mover; And a first lowering part generating an inertial force greater than the frictional force of the first and second movers. The second waveform may include: a second rising part generating an inertial force smaller than the frictional force of the first and second movers; And a second lowering part generating an inertial force greater than the frictional force of the first and second movers. The third waveform includes: a third lifter generating an inertial force smaller than the friction force of the first and second movers; And a third lowering portion generating an inertial force of the first mover smaller than the frictional force of the first mover and an inertial force of the second mover greater than the frictional force of the second mover.

On the other hand, the linear actuator having a multiple degree of freedom according to the second embodiment of the present invention is composed of the first, second, and third movers of the mover, the friction force of the first mover having the smallest mass among the three movers It is characterized by the smallest frictional force of the third mover having the largest and largest mass. At this time, the driving circuit applies a driving voltage having a fourth waveform for moving only the first mover, a fifth waveform for moving only the second mover, or a sixth waveform for moving only the third mover, to the piezoelectric body. The fourth waveform may further include: a fourth rising part generating an inertia force of the first mover smaller than the friction force of the first mover and an inertia force of the second and third movers greater than the friction force of the second and third movers; And a fourth lowering portion generating an inertia force greater than the friction force of the first, second and third movers. The fifth waveform may further include: a fifth rising part generating an inertia force of the third mover larger than the friction force of the third mover and an inertia force of the first and second movers smaller than the friction force of the first and second movers; And a fifth lower portion that generates an inertial force of the first mover smaller than the friction force of the first mover and generates an inertial force of the second and third movers larger than the friction force of the second and third movers. The sixth waveform includes: a sixth lift unit generating an inertial force of the first, second, and third movers smaller than the friction force of the first, second, and third movers; And a sixth lower portion generating an inertial force of the third mover larger than the friction force of the third mover and an inertia force of the first and second movers smaller than the friction force of the first and second movers.

A method of driving a piezoelectric linear driver having multiple degrees of freedom according to the present invention includes a frame; A piezoelectric body once fixed to the frame; A drive shaft fixed perpendicular to the other end surface of the piezoelectric body; A plurality of movers fitted to the drive shaft with different frictional forces with the drive shaft; A driving circuit for applying a driving voltage having a predetermined waveform to the piezoelectric body; A driving method of a piezoelectric linear driver having a multiple degree of freedom comprising a control unit for controlling the driving circuit, the method comprising: applying a driving voltage to the piezoelectric body by the driving circuit (S100); Driving the drive shaft as the piezoelectric body is expanded or contracted (S200); Generating an inertial force of the movers (S300); And a step of moving or retracting the mover whose inertia force is smaller than the friction force among the movers (S400). At this time, before the applying step (S100), the control unit further includes the step of controlling the waveform of the driving voltage generated in the opening and closing of the driving circuit and the driving circuit.

A focus control apparatus using a piezoelectric linear driver having a multiple degree of freedom according to the present invention includes a piezoelectric linear driver having a multiple degree of freedom; A lens frame fixed to one side of each of the movers; And a lens fitted to and fixed to each of the lens frames. At this time, it is further provided with an image sensor that is optically aligned with the lenses.

As described above, the piezoelectric linear driver having a multiple degree of freedom according to the present invention, a driving method thereof, and a focus adjusting device using the same have advantages in that a plurality of movers can be linearly driven freely to obtain a plurality of degrees of freedom. . Therefore, there is an advantage that can be reduced in size, thin and light driving unit such as electronic products, robots, optical devices.

In addition, since it is possible to drive efficiently at low power and has a simple structure, there is an advantage of facilitating the design of a product using a piezoelectric linear driver.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to components of each drawing, the same reference numerals are used for the same components as much as possible even if they are shown in different drawings.

First, a piezoelectric linear driver having a multiple degree of freedom according to the present invention will be described.

[First Embodiment]

4 is a schematic perspective view of a piezoelectric linear driver having a multiple degree of freedom according to a first embodiment of the present invention. The piezoelectric linear driver 100 having a multiple degree of freedom according to the first embodiment of the present invention includes a frame 110, a piezoelectric body 120, a drive shaft 130, a mover 141, 142, a drive circuit 150, and a controller 160. It consists of.

The frame 110 has a predetermined shape and supports one side of the piezoelectric body 120.

The piezoelectric body 120 is configured in a form of stacked plate-like piezoelectric elements. The piezoelectric element uses a composite oxide material of lead (Pb), zirconium (Zr), and titanium (Ti) called PZT. The piezoelectric body 120 has a property of expanding or contracting when a driving voltage is applied. One end of the piezoelectric body 20 is fixed to the frame 100.

The drive shaft 130 has a long rod shape having a circular cross section. One end of the driving shaft 130 is fixed perpendicularly to the other end surface of the piezoelectric body 120. Therefore, the drive shaft 130 is driven in the expansion or contraction direction as the piezoelectric body 120 expands or contracts.

According to the first embodiment, the mover is composed of two first movers 141 and two second movers 142. The movers 141 and 142 have a hollow and are fitted to the drive shaft 130. In this case, the first mover 141 and the second mover 142 has a different mass, the mass (m ₁ ) of the first mover 141 is smaller than the mass (m ₂ ) of the second mover 142. To do that. According to FIG. 4, the first mover 141 is fitted to the drive shaft 130 before the second mover 142. The arrangement of the first mover 141 and the second mover 142 may be different. However, according to the first embodiment, the first mover 141 and the second mover 142 should have different frictional forces from the drive shaft 130 generated when the drive shaft 130 is driven. At this time, the friction force f ₁ of the first mover 141 having a small mass is set larger than the friction force f ₂ of the second mover 142.

Meanwhile, the frictional forces f ₁ and f _{2 of} the first mover 141 and the second mover 142 are defined as the product of the friction coefficient μ and the vertical drag N, and thus the first and second movers 141 and 142. ) And the drive shaft 130 is designed to adjust the friction coefficient (μ) and the vertical drag (N).

The driving circuit 150 is electrically connected to the piezoelectric body 120. The driving circuit 150 incorporates a function generator to apply a driving voltage having a predetermined waveform to the piezoelectric body 120. The driving circuit 150 may include a positive driving voltage having the first waveform 200, the second waveform 300, or the third waveform 400 illustrated in FIGS. 5, 7, and 9, respectively. 120 to advance the movers 141 and 142. In this case, the first waveform 200, the second waveform 300, and the third waveform 400 have rising portions 210, 310, and 410 and falling portions 220, 320, and 420 having predetermined slopes. A detailed description thereof will be described later. Then, a negative driving voltage indicated by a dotted line is applied to the piezoelectric body 120 to retract the movers 141 and 142.

The controller 160 is electrically connected to the driving circuit 150 to open and close the driving circuit 150 or control the waveforms 200, 300, and 400 of the driving voltage generated by the driving circuit 150.

Hereinafter, an operation of the piezoelectric linear driver 100 having multiple degrees of freedom according to the first embodiment of the present invention will be described with reference to FIGS. 4 to 10.

First, only the first mover 141 will be described with reference to FIGS. 5 and 6.

The driving voltage having the first waveform 200 is shown in FIG. 5. The piezoelectric body 120 expands in the direction of the arrow shown in FIG. 6A by the rising portion 210 of the first waveform 200, and is illustrated by the falling portion 220 of the first waveform 200. It contracts in the direction of the arrow shown in 6 (b). In this case, since the driving shaft 130 is fixed to the piezoelectric body 120, the driving shaft 130 is driven in the direction in which the piezoelectric body 120 expands or contracts.

As the driving shaft 130 is driven, frictional forces f ₁ and f ₂ between the first and second movers 141 and 142 and the driving shaft 130 are generated in the driving direction of the driving shaft 130. That is, as shown in FIG. 6A, when the piezoelectric body 120 is inflated, frictional forces f ₁ and f ₂ are generated in the expansion direction of the piezoelectric body 120, and when the piezoelectric body 120 shrinks, the piezoelectric body 120 is depressed. Friction forces f ₁ and f ₂ are generated in the contracting direction of. At this time, the mass (m ₁₎ of the above described first mover 141, the frictional force (f _1), the second slider 142, the frictional force can significantly be set higher than (f _1), the first mover 141 of the second It is set smaller than the mass m ₂ of the two movers 142.

As shown in FIG. 5, the first waveform 200 includes a first rising part 210 having a relatively gentle inclination and a first falling part 220 that is inclined sharply. At this time, the inclination of the first rising part 210 and the first lowering part 220 is the acceleration a _E1 that the driving shaft 130 has when the piezoelectric body 120 expands and the driving shaft 130 when the piezoelectric body 120 contracts. ) Determines the magnitude and direction of the acceleration a _S1 . Thus, the mass m ₁ of the first mover 141 is the piezoelectric body 120 is the inertia of the m ₁ a _E1 size is generated during the expansion, the mass m ₂ of the second mover 142 m ₂ a _E1 size Inertia is generated. In addition, when the piezoelectric body 120 contracts, the first mover 141 generates an inertial force of m ₁ a _S1 , and the second mover 142 generates an inertial force of m ₂ a _S1 . In this case, the inertial forces m ₁ a _E1 , m ₂ a _E1 , m ₁ a _S1 , m ₂ a _{S1 of} the first mover 141 and the second mover 142 are respectively the friction forces f ₁ and f ₂ described above. Occurs in the opposite direction of). The mass sizes of the movers 141 and 142 are m ₁ <m ₂ , and the magnitude of the inertial force of the movers 141 and 142 is m ₁ a _E1 <m ₂ a _E1 <m ₁ a _S1 <m ₂ a _S1 .

On the other hand, the horizontal portion 230 having a constant driving voltage between the first rising portion 210 and the first falling portion 220 is not an important part in the first waveform 200 of the present embodiment because the portion does not generate the acceleration force. . Accordingly, the first waveform 200 may have a rectangular shape having a first rising part 210, a first falling part 220, and a horizontal part 230, as shown in FIG. 5, and the first rising part. It is also possible to have a sawtooth wave shape of a triangular shape consisting of 210 and the first lower portion (220). In addition, the figure shows the shape of the waveform having a rough slope, the exact slope value, the frequency value, the amplitude value of the driving voltage, etc. of each waveform may be different, the inertial force of the generated movers (141, 142) is m ₁ a _E1 <m ₂ a _E1 <m ₁ a _S1 <m ₂ a _S1 may be satisfied. The same applies to driving voltages having other waveforms to be described later.

The relatively gentle slope of the riser 210 of the first waveform 200 is smaller than the frictional force f ₁ of the first mover 141 as shown in FIG. 6A. Generates an inertia force (m ₁ a _E1 ) of. Then, the inertial force m ₂ a _E1 of the second mover 142 is greater than the friction force f _{2 of} the second mover 142. Therefore, since the frictional force f ₁ is greater than the inertia force m ₁ a _E1 , the first mover 141 is advanced along the driving shaft 120 by S ₁ length, and the second mover has an inertia force of frictional force f ₂ . Since it is smaller than (m ₂ a _E1 ), it does not move with the drive shaft 120, and remains in place.

In addition, the steep slope of the lower portion 220 of the first waveform 200 has an inertial force greater than the friction force f ₁ of the first mover and the friction force f ₂ of the second mover, as shown in FIG. (m ₁ a _S1 , m ₂ a _S1 ) is generated. Accordingly, the first mover 141 and the second mover 142 do not move in the direction of the arrow shown in FIG. 6B together with the drive shaft 120 and remain in place.

As a result, only the first mover 141 may be advanced by S ₁ length by one unit waveform 200. Therefore, the driving voltage is a pulse form, the operation described above is repeated, it is possible to advance the mover 40 by a desired distance.

On the contrary, as shown in FIG. 5, when the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120, only the first mover 141 may be retracted by the length S ₁ by the same principle as described above. Therefore, the driving voltage having the first waveform 200 can linearly move only the first mover 141.

Next, the first mover 141 and the second mover 142 are simultaneously moved with reference to FIGS. 7 and 8. The operating principle of the first mover 141 and the second mover 142 is the same as described above.

The gentle slope of the raised portion 310 of the second waveform 300 shown in FIG. 7 is less than the frictional force f _{1 of} the first mover 141 as shown in FIG. Generates inertia force m ₁ a _E2 . In addition, the inertial force m ₂ a _{E 2} of the second mover 142 smaller than the friction force f _{2 of} the second mover 142 is generated.

Accordingly, the first mover 141 is advanced along the driving shaft 120 by S ₂ length and the second mover is S ₃ length. In addition, the sharp slope of the lower portion 320 of the second waveform 300 has a frictional force f ₁ of the first mover 141 and a frictional force of the second mover 142 as shown in FIG. Generates an inertia force (m ₁ a _S2 , m ₂ a _S2 ) greater than (f ₂ ). Accordingly, the first mover 141 and the second mover 142 do not move together with the drive shaft 120 and remain in place.

As a result, the first mover 141 is advanced by S ₂ and the second mover 142 is advanced by S ₃ by one unit waveform 300. When the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120, the first mover 141 and the second mover 142 may be simultaneously retracted. Accordingly, the driving voltage having the second waveform 300 may linearly move the first mover 141 and the second mover 142 simultaneously.

Next, only the second mover 142 will be described with reference to FIGS. 9 and 10.

The gentle slope of the raised portion 310 of the third waveform 400 shown in FIG. 9 is smaller than the frictional force f ₁ of the first mover 141 as shown in FIG. The inertial force m ₁ a _E3 of 141 is generated, and the inertial force m ₂ a _E2 of the second mover 142 is smaller than the friction force f _{2 of} the second mover. Accordingly, the first mover 141 and the second mover 142 move forward together with the drive shaft 120.

In addition, a relatively steep slope of the lower portion 420 of the third waveform 400 is smaller than the friction force f ₁ of the first mover 141 as shown in FIG. 10B. The inertial force m ₁ a _{S3 of} ) is generated, and the inertial force m ₂ a _S3 of the second mover 142 is greater than the friction force f _{2 of} the second mover 142. Accordingly, the first mover 141 returns to the initial state as shown in FIG. 10C and the second mover 142 remains in place.

As a result, one unit waveform 400 has the same result as the first mover 141 stops in place, and only the second mover 142 is advanced by S ₄ length. When the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120, only the second mover 142 may be retreated. Therefore, the driving voltage having the third waveform 400 can linearly move only the second mover 142.

The controller 160 opens or closes the driving circuit 150 or selectively changes the first waveform 200, the second waveform 300, or the third waveform 400 of the driving voltage described above. 141 and the second mover 142 can be moved freely. Accordingly, the piezoelectric linear driver 100 having the multiple degree of freedom according to the first embodiment of the present invention may advance or retract the first mover 141 and the second mover 142, respectively, and the first mover 141. And the second mover 142 can be moved forward or backward at the same time.

The piezoelectric linear driver 100 having the multiple degrees of freedom of the first embodiment has two degrees of freedom, and can perform various operations as compared with the conventional piezoelectric linear driver having one degree of freedom, and can drive efficiently with low power. In addition, it is possible to reduce the thickness of the drive unit of the electronic products, robots, optical devices, etc. in which the piezoelectric linear driver 100 is used.

[Second Embodiment]

11 is a schematic perspective view of a piezoelectric linear driver having a multiple degree of freedom according to a second embodiment of the present invention. The piezoelectric linear driver 100 ″ having multiple degrees of freedom according to the second embodiment of the present invention includes waveforms of driving voltages 500, 600, and 700 shown in FIGS. 12, 14, and 16 applied by the movers 143, 144, 145, and the driving circuit 150, respectively. ), And the rest of the configuration is the same as in the first embodiment.

The mover of the piezoelectric linear driver 100 "having the multiple degree of freedom according to the second embodiment of the present invention is composed of three of the first mover 143, the second mover 144 and the third mover 145. The first mover has the smallest mass m ₁ and the largest friction force f ₁ with the drive shaft 130. The third mover 145 has the largest mass m ₃ and the drive shaft. The frictional force f ₃ with 130 is set to be the smallest, and the second mover 144 has a medium size of mass m ₂ and a frictional force f ₂ .

The driving circuit 150 includes a positive driving voltage having the fourth waveform 500, the fifth waveform 600, or the sixth waveform 700 illustrated in FIGS. 12, 14, and 16, respectively. 120 to advance the movers 143, 144, and 145. In this case, the fourth waveform 500, the fifth waveform 600, and the sixth waveform 700 include rising parts 510, 610, 710, and falling parts 520, 620, and 720 having a predetermined slope. A detailed description thereof will be described later. Then, the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120 to retract the movers 143, 144, and 145.

Hereinafter, the operation of the piezoelectric linear driver 100 "having the multiple degree of freedom according to the second embodiment of the present invention will be described. The operation principle of the movers 143, 144 and 145 is the same as that of the first embodiment.

First, only the first mover 143 will be described with reference to FIGS. 12 and 13.

The relatively gentle slope of the fourth wave 500 rising portion 510 shown in FIG. 12 is smaller than the frictional force f ₁ of the first mover 143 as shown in FIG. 13A. The inertia force m ₁ a _E4 of the mover 143 is generated. The second friction force of the mover 144 (f ₂₎ greater than the second generating an inertial force (m ₂ a _E4) of the slider (144) and the friction force of the third mover (145) (f _3), a large third than It generates an inertial force (a ₃ m _E4) of the mover (145). Therefore, only the first mover 143 is advanced along with the drive shaft 120 by S ₅ length.

The abrupt slope of the lower portion 520 of the fourth waveform 500 is a frictional force f ₁ of the first mover 143 and a frictional force of the second mover 144 as illustrated in FIG. 13B. f ₂ ) and the inertia forces m ₁ a _S4 , m ₂ a _S4 , m ₃ a _S4 greater than the frictional force f ₃ of the third mover 145. Accordingly, the first mover 143, the second mover 144, and the third mover 145 do not move together with the drive shaft 120, but remain in place.

As a result, the first mover 143 is advanced by S ₅ length by one unit waveform 500. When the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120, only the first mover 143 may be retreated. Therefore, the driving voltage having the fourth waveform 500 can linearly move only the first mover 143.

Next, referring to FIGS. 14 and 15, only the second mover 144 is moved.

Illustrated in Figure 14, a fifth waveform 600 rises 610 of the small inertial force than the first slider 143, as shown in a relatively gradual slope in FIG. 15 (a) (m ₁ a _E5) and of The inertial force m ₂ a _{E 5} is generated smaller than the frictional forces f ₁ and f ₂ of the second mover 144. Then, the inertial force m ₃ a _{E 5} of the third mover 145 is greater than the friction force f _{3 of} the third mover 145. Therefore, only the first mover 143 and the second mover 144 are advanced.

The relatively steep slope of the fifth waveform 600 and the fifth lower portion 620 generates an inertial force m1a _S5 of the first mover 143 smaller than the friction force f _{1 of} the first mover 143. Then, an inertial force m ₂ a _S5 greater than the friction force f ₂ of the second mover 144 is generated, and an inertia force m of the second mover 144 that is greater than the friction force f ₃ of the third mover 145. ₂ a _S5 ). Accordingly, the first mover 143 returns to the initial state, and the second mover 144 and the third mover 145 do not move together with the drive shaft 120 and remain in place.

As a result, the second mover 144 may be advanced by S ₅ length by one unit waveform 600 as shown in FIG. 14. When the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120, only the second mover 144 may be retreated. Therefore, the driving voltage having the fifth waveform 600 can linearly move only the first mover 143.

Next, referring to FIGS. 16 and 17, only the third mover will be described.

The inclination of the rising portion 710 of the sixth waveform 700 shown in FIG. 16 is very gentle so that the sixth rising portion 710 of the sixth waveform 700 is formed as shown in FIG. Inertia force (m ₁ a _E6 , m ₂ a _E6 , m ₃ a _E6 ) less than the frictional force (f ₁ , f ₂ , f ₃ ) of the first mover 143, the second mover 144, and the third mover 145 Generates. Accordingly, the first mover 143, the second mover 144, and the third mover 145 all move forward.

In addition, a relatively steep slope of the sixth waveform 700 and the sixth lower portion 720 shown in FIG. 16 is greater than the friction force f _{3 of} the third mover 145. ₃ a _S6) generation and, the friction force of the first mover 143 (small inertia than f ₁₎ (m ₁ a _S6) and a second frictional force (f _2), a small force of inertia (m ₂ a _S6 than the mover 144 ). Thus, only the first mover and the second mover return to the initial state, and the third mover remains in place.

As a result, one unit waveform 700 allows the third mover to advance S ₆ length as shown in FIG. 17. When the negative driving voltage indicated by the dotted line is applied to the piezoelectric body 120, only the third mover 145 may be retreated. Accordingly, the driving voltage having the sixth waveform 700 may linearly move only the first mover 143.

The controller 160 opens or closes the driving circuit 150 or selectively changes the first waveform 200, the second waveform 300, or the third waveform 400 of the driving voltage described above. 143), the second mover 144 and the third mover 145 may be driven freely.

Accordingly, the multi-degree of freedom linear driver 100 ″ according to the second embodiment of the present invention may move forward or backward only the first mover 143, the second mover 144, or the third mover 145. In this process, any two movers can be moved forward or backward at the same time, and all movers 143, 144 and 145 can be moved forward or backward at the same time. Consequently, the piezoelectric linear actuator 100 "having the multiple degree of freedom of the second embodiment is free. 3, it is possible to perform a variety of operations compared to the piezoelectric linear driver having a conventional degree of freedom of 1, it is possible to drive efficiently with low power. In addition, it is possible to reduce the thickness of the driving unit such as electronic products, robots, optical devices, etc. in which the piezoelectric linear driver 100 "is used.

Meanwhile, according to the first embodiment or the second embodiment described above, the piezoelectric linear actuators 100 and 100 ″ have 2 or 3 degrees of freedom, but may be designed to have 4 or more degrees of freedom using the same principle.

Hereinafter, a driving method of a piezoelectric linear driver having a multiple degree of freedom according to the present invention will be described with reference to FIG. 18.

A method of driving a piezoelectric linear driver having a multiple degree of freedom according to the present invention is a method for driving a piezoelectric linear driver having a multiple degree of freedom, the step of applying a driving voltage to a piezoelectric material (S100), driving a driving shaft (S200). In this case, the inertia force of the movers is generated (S300), and the inertia force is smaller than the friction force. The controller 160 may further include opening and closing the driving circuit 150 or controlling the waveform of the driving voltage generated by the driving circuit 150 (S500).

In the step S100 of applying the driving voltage to the piezoelectric body 120, the driving circuit 150 applies the driving voltage having the predetermined waveforms 200, 300, 400, 500, 600, and 700 to the piezoelectric body 120. In this case, the predetermined waveforms 200, 300, 400, 500, 600, and 700 have rising portions 210, 310, 410, 510, 610, 710, and falling portions 220, 320, 420, 520, 620, and 720 having a predetermined slope to generate acceleration when the piezoelectric body 120 expands or contracts.

In the driving step S200 of the driving shaft, the driving shaft 130 is driven as the piezoelectric body 120 expands or contracts by the applied driving voltage. At this time, the drive shaft 130 is driven at the acceleration described above.

In the step S300 of generating the inertial force of the movers, an inertial force is generated in the plurality of movers 141, 142, 143, 144, and 145 by the driving of the drive shaft 130. At this time, the mass of the movers (141, 142, 143, 144, 145) and the acceleration of the drive shaft 130 are different, respectively, the movers (141, 142, 143, 144, 145) are generated inertial forces of different sizes.

The step of moving or retracting the mover whose inertia force is smaller than the friction force (S400) is to move forward or retreat when the inertia force of the movers 141, 142, 143, 144 and 145 is less than the friction force generated between the movers 141, 142, 143, 144 and 145 and the drive shaft 130. That is, the frictional forces of the movers 141, 142, 143, 144, and 145 are set to different magnitudes, and the inertia forces of the movers 141, 142, 143, 144, and 145 are adjusted to a driving voltage having a predetermined waveform, thereby driving or simultaneously driving the movers 141, 142, 143, 144, and 145, respectively. .

Meanwhile, before the step S100 of applying the driving voltage to the piezoelectric body 120, the controller 160 opens or closes the driving circuit 150 or controls the waveform of the driving voltage generated by the driving circuit 150. Can be done. In this step, the driving circuit 150 may apply the driving voltage to the piezoelectric body 120 or remove the applied state to turn on / off the driving of the movers 141, 142, 143, 144, and 145. The driving states of the movers 141, 142, 143, 144, and 145 may be controlled by changing the waveforms 200, 300, 400, 500, 600, 700 of the driving voltages generated by the driving circuit 150.

Hereinafter, a focus adjusting apparatus using a piezoelectric linear driver 100 having a multiple degree of freedom according to the present invention will be described with reference to FIG. 19.

As shown in FIG. 19, the focus adjusting apparatus of the present invention includes a piezoelectric linear driver 100 having the multiple degrees of freedom described above, a lens frame 172 and 182 fixed to one side of each of the movers 141 and 142 of the piezoelectric linear driver, And lenses 174 and 184 that are fitted into and fixed to the lens frames 172 and 182.

In other words, as shown in FIG. 19, the first micro lens 170 includes a first lens frame 172 fixed to the first mover and a first lens 174 fitted to the first lens frame 172. It is composed. The second micro lens 180 includes a second lens frame 182 fixed to the second mover, and a second lens 184 fitted to the second lens frame 182. In addition, the image sensor 190 is optically aligned with the second micro lens 180 and the first micro lens 170 to photograph the subject, and converts the image into an electrical image signal.

The focusing apparatus of the present invention drives the first mover 141 and the second mover 142 of the piezoelectric linear driver 100 to free the alignment of the first microlens 170 and the second microlens 180. I can adjust it freely. Therefore, the focusing apparatus of the present invention can be used for magnification adjustment, automatic focusing function, etc. of an optical device such as a camera.

The focus adjusting device of the present invention can simplify the structure of a drive unit of an optical device such as a camera, thereby providing ease of design. It also enables efficient operation at low power.

In the present embodiment, the case where the piezoelectric linear driver 100 having the multiple degree of freedom of the first embodiment is used has been described, but it is also possible to use the piezoelectric linear driver 100 "of the second embodiment.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be readily apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention, and all such changes and modifications are It is obvious that it belongs to the scope of the appended claims.

1 is a schematic perspective view of a lens adjustment apparatus to which a piezoelectric linear driver according to the prior art is applied.

FIG. 2 is a schematic waveform diagram of a driving voltage applied to the piezoelectric linear driver of FIG. 1. FIG.

3 is a conceptual diagram illustrating the principle of moving the mover of FIG.

4 is a schematic perspective view of a piezoelectric linear driver having a multiple degree of freedom according to a first embodiment of the present invention.

5 is a schematic waveform diagram showing a first waveform;

FIG. 6 is a conceptual diagram illustrating moving only a first mover of FIG. 4; FIG.

7 is a schematic waveform diagram showing a second waveform;

FIG. 8 is a conceptual diagram for explaining simultaneously moving a first mover and a second mover of FIG. 4; FIG.

9 is a schematic waveform diagram showing a third waveform;

FIG. 10 is a conceptual view illustrating moving only a second mover of FIG. 4; FIG.

11 is a schematic perspective view of a piezoelectric linear driver having a multiple degree of freedom according to a second embodiment of the present invention.

12 is a schematic waveform diagram showing a fourth waveform;

FIG. 13 is a conceptual view illustrating moving only the first mover of FIG. 11; FIG.

14 is a schematic waveform diagram illustrating a fifth waveform;

FIG. 15 is a conceptual diagram illustrating moving only a second mover of FIG. 11; FIG.

16 is a schematic waveform diagram showing a sixth waveform;

FIG. 17 is a conceptual view illustrating moving only a third mover of FIG. 11; FIG.

18 is a block diagram illustrating a method of driving a piezoelectric linear driver having a multiple degree of freedom according to the present invention.

19 is a schematic perspective view showing a focus control apparatus using a piezoelectric linear driver having a multiple degree of freedom according to the present invention.

* Description of the symbols for the main parts of the drawings *

100: piezoelectric linear driver having multiple degrees of freedom 110: frame

120: piezoelectric 130: drive shaft

141: first mover 142: second mover

143: first mover 144: second mover

145: third mover 150: drive circuit

160: control unit 170: first micro lens

180: second micro lens 190: image sensor

200: first waveform 210: first rising part

220: first lower portion 300: second waveform

310: second rising part 320: second falling part

400: third waveform 410: third rising part

420: third lower portion 500: fourth waveform

510: fourth rising portion 520: fourth falling portion

600: fifth waveform 610: fifth rising part

620: fifth lower portion 700: sixth waveform

710: sixth rising portion 720: sixth falling portion

Claims (16)

frame; A piezoelectric body having one end fixed to the frame; A driving shaft having one end fixed to the other end surface of the piezoelectric body; A plurality of movers fitted to the drive shaft with different frictional forces with the drive shaft; A driving circuit for applying a driving voltage having a predetermined waveform to the piezoelectric body; And A control unit for controlling the driving circuit; And at least one of the plurality of movers in accordance with the waveform of the driving voltage. The method of claim 1, The mover is a piezoelectric linear actuator having a multiple degree of freedom, characterized in that having a different mass. The method of claim 2, And two movers, and a friction force of the first mover having a relatively small mass is greater than that of a second mover having a relatively large mass. The method of claim 3, The driving circuit may be configured to apply a driving voltage to the piezoelectric body having a first waveform for moving only the first mover, a second waveform for moving the first and second movers, or a third waveform for moving only the second mover. A piezoelectric linear driver having multiple degrees of freedom. The method of claim 4, wherein The first waveform may include: a first rising part configured to generate an inertia force of the first mover smaller than the friction force of the first mover and an inertia force of the second mover greater than the friction force of the second mover; And a first lowering part generating an inertia force greater than the friction force of the first and second movers. The method of claim 4, wherein The second waveform may include: a second rising part generating an inertial force less than the frictional force of the first and second movers; And a second lowering part generating an inertia force greater than the friction force of the first and second movers. The method of claim 4, wherein The third waveform may include a third lifter generating an inertial force less than the friction force of the first and second movers; And a third lowering part generating an inertia force of the first mover smaller than the friction force of the first mover and a second inertia force of the second mover greater than the friction force of the second mover. . The method of claim 2, The mover is composed of first, second, and third movers, wherein the frictional force of the first mover having the smallest mass among the three movers is the largest and the frictional force of the third mover having the largest mass is the smallest. Piezoelectric linear actuator with multiple degrees of freedom. The method of claim 8, The driving circuit applies a driving voltage having a fourth waveform for moving only the first mover, a fifth waveform for moving only the second mover, or a sixth waveform for moving only the third mover, to the piezoelectric body. Piezoelectric linear actuator with multiple degrees of freedom. 10. The method of claim 9, The fourth waveform may include: a fourth lifter generating an inertia force of the first mover smaller than the friction force of the first mover and an inertia force of the second and third movers greater than the friction force of the second and third movers; And a fourth lowering part generating an inertia force greater than the friction force of the first, second, and third movers. 10. The method of claim 9, The fifth waveform may include: a fifth lift unit generating an inertia force of the third mover greater than the friction force of the third mover and an inertia force of the first and second movers smaller than the friction force of the first and second movers; And a fifth lower portion which generates an inertial force of the first mover smaller than the friction force of the first mover and generates an inertial force of the second and third movers larger than the friction force of the second and third movers. Piezoelectric linear actuator having a degree of freedom. 10. The method of claim 9, The sixth waveform includes: a sixth lift unit generating an inertial force of the first, second and third movers smaller than the friction force of the first, second and third movers; And a sixth lower portion generating the inertia force of the third mover larger than the friction force of the third mover and the inertia force of the first and second movers smaller than the friction force of the first and second movers. Piezoelectric linear actuator with freedom. frame; A piezoelectric one end of which is fixed to the frame; A driving shaft fixed perpendicular to the other end surface of the piezoelectric body; A plurality of movers fitted to the drive shaft with different frictional forces with the drive shaft; A driving circuit for applying a driving voltage having a predetermined waveform to the piezoelectric body; In the driving method of the piezoelectric linear driver having a multiple degree of freedom comprising a control unit for controlling the drive circuit The driving circuit applying the driving voltage to the piezoelectric body (S100); Driving the driving shaft as the piezoelectric body is expanded or contracted (S200); Generating an inertial force of the movers (S300); And The method of driving a piezoelectric linear actuator having a multiple degree of freedom characterized in that it comprises the step (S400) of the mover, the inertia force is smaller than the friction force of the movers. The method of claim 13, The control method of the piezoelectric linear actuator having a multiple degree of freedom further comprising the step of controlling the opening and closing of the drive circuit and the waveform of the drive voltage generated in the drive circuit before the applying step (S100). A piezoelectric linear driver having a multiple degree of freedom of any one of claims 1 to 12; A lens frame fixed to one side of each of the movers; And And a lens that is inserted into and fixed to each of the lens frames. The method of claim 15, And a piezoelectric linear driver having multiple degrees of freedom, further comprising an image sensor optically aligned with the lenses.

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