KR20040027753A - small piezoelectric or electrostrictive linear motor - Google Patents

Abstract

PURPOSE: A small-sized piezoelectric/electrostrictive ultrasonic linear motor is provided to perform a linear motion and control accurately a position according to a period of an applied voltage by applying a pulse type voltage of an ultrasonic range. CONSTITUTION: A small-sized piezoelectric/electrostrictive ultrasonic linear motor includes a piezoelectric/electrostrictive substrate(10), an elastic substrate(20), a moving shaft(30), and a moving body(40). Electrodes are formed on both sides of the piezoelectric/electrostrictive substrate(10). The piezoelectric/electrostrictive substrate(10) is adhered on one side or both sides of the elastic substrate(20). The moving shaft(30) is fixed on the elastic substrate or the piezoelectric/electrostrictive substrate adhered on one side or both sides of the elastic substrate(20). The moving shaft is vertical to the elastic substrate. The moving body(40) is movable on the moving shaft.

Description

Small piezoelectric or electrostrictive linear motor

In case of small stepping motor that can be mounted for camera lens driving of mobile phone or PDA, reduction gear and cam should be used to convert fast rotation to linear movement and backlash in forward or reverse rotation. Error occurs and power consumption is limited, so it is restricted. In addition, such an electromagnetic drive motor has disadvantages such as high current and heat generation.

In general, a linear motor using piezoelectric / electric warp substrates repeats vertical and horizontal vibrations by combining a method of driving with a traveling wave generated by a flexural wave and a longitudinal vibration and a transversal vibration actuator. And a standing waveform method for generating a driving device for driving the mover is known. Standing wave type The basic type of linear motor uses plural vibrations generated by combining vibrators with different modes of operation, and mechanical displacement on piezoelectric / electric distortion actuators that vibrate in the vertical and horizontal directions. Consists of a contact for transmitting. The longitudinal vibration of the piezoelectric vibrator is transmitted to the vibrating portion (contacting portion) in contact with the mover, and the moving body is driven by friction between the mover and the contacting portion. Various methods have been proposed for such vibration transmission, but there are many problems in practical use because it is difficult to secure a constant vibration amplitude due to wear during continuous driving.

An object of the present invention is proposed to solve the above problems, and relates to a small piezoelectric / electric distortion ultrasonic linear motor that can be mounted for driving a camera lens of a mobile phone or PDA, etc. by applying a pulse voltage in the ultrasonic region. The present invention provides a compact piezoelectric / electric distortion ultrasonic linear motor capable of precise position adjustment, easy manufacturing process, and simple structure according to a linear or reverse linear motion and a period of applied voltage.

Fig. 1. Bending deformation principle of the piezoelectric or electro-distortion substrate 10 and the elastic body 20 used in the present invention

2. Principle of a compact piezoelectric / electric distortion ultrasonic linear motor applied to the present invention.

3. A saw tooth pulse wave for driving a small piezoelectric / electric distortion ultrasonic linear motor of the present invention.

Figure 4 (a). Structure of the first embodiment of the small piezoelectric / electric distortion ultrasonic linear motor of the present invention.

4 (b). Structure of the second embodiment of the small piezoelectric / electric distortion ultrasonic linear motor of the present invention.

Figure 4 (c). Front and side view structures of a third embodiment of the small piezoelectric / electric distortion ultrasonic linear motor of the present invention.

5 (a) and 5 (b) The structure of the movable body 40 of the small piezoelectric / electric distortion ultrasonic linear motor of the present invention

6. The principle showing the movement of the moving body 40 and the stator of the small piezoelectric / electric distortion ultrasonic linear motor of the present invention.

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

10, 12: piezoelectric / electric distortion substrate 20: elastomer substrate,

25: fixed end, 30: moving shaft,

35: moving shaft fixed end, 40: moving body,

42: friction material, 44: heavy material,

46: spring,

First, before explaining in detail through the preferred embodiment of the present invention will be described the piezoelectric effect and the vibration theory according to the basic theory applied to the present invention in order to help the understanding of the present invention.

The piezoelectric effect refers to mechanical deformation when a crystal is pressurized to generate charge in the crystal or, conversely, to apply an electric field to the crystal. The piezoelectric plate 10 exhibiting such a piezoelectric effect is characterized by having mechanical displacement of contraction and expansion according to the polarization direction and the direction of the electric field.

1 shows a deformation of the piezoelectric plate 10 according to the electric field and the polarization direction.

1 (1) shows a displacement pattern when an electric field is applied to the piezoelectric plate 10 polarized in one direction. When the polarization direction of the piezoelectric plate 10 is the same as the direction of the electric field, expansion occurs in the z direction of the piezoelectric plate 10, and contraction occurs in the x moving axis direction due to a posson ratio. When the direction is reversed, expansion occurs in the x-axis direction while shrinkage occurs in the z direction of the piezoelectric substrate 10.

FIG. 1 (b) shows the displacement shape when the piezoelectric plate 10 and the elastic body 20 are coupled. The piezoelectric plate 10 exhibits a displacement form as shown in FIG. 1 (a), and the elastic body 20 attached to the piezoelectric plate 10 causes bending displacement as the piezoelectric plate 10 contracts and expands.

The part shown by the dotted line of FIG. 1 (b) shows the bending shape of the elastic body 20 when the piezoelectric plate 10 expands in the z direction. This curved displacement is due to the expansion of the piezoelectric plate 10 and the behavior of the elastic body 20 due to the fixed end 25 of the elastic body 20 being fixed.

FIG. 1 (c) shows a state in which the elastic deformation of the elastic body 20 occurs in the z direction as the piezoelectric plate 10 is expanded in the x direction. In the displaced state as shown in FIG. 1 (b), when the direction of the electric field is changed instantaneously, the displacement form of the piezoelectric plate 10 is changed, and the elastic body 20 is z due to the instantaneous acceleration force and expansion in the x direction. The bending displacement appears in the direction.

Although the theory of bending displacement when an electric field is applied to the piezoelectric plate has been described, the same bending displacement phenomenon occurs even when a piezoelectric plate is used instead of the piezoelectric plate. The warping phenomenon refers to a phenomenon in which mechanical deformation, that is, distortion occurs when an electric field is applied to the warping material. In the case of using an electrodistortion substrate instead of the piezoelectric substrate in FIG.

Therefore, the present invention will be described with respect to the development of a linear motor for generating a bending displacement by using the piezoelectric substrate and the electrostrictive substrate to convert it to a linear displacement.

The piezoelectric substrate or the electrostrictive substrate 10 of the present invention may be used as the piezoelectric substrate or the electrostrictive substrate 10 of the material such as single crystal, polycrystalline ceramics, polymer, or the like in the thickness direction of the substrate. The elastic body 20 may use an elastic body having a predetermined thickness, and used a phosphor bronze material in the present invention. When the moving shaft is installed in the elastic body 20 may be used to produce a hole (hole) in which the moving shaft 30 can be inserted in the center.

As shown in FIG. 1, when an electric field is applied in a state in which the piezoelectric plate or electro-distortion board 10 and the elastic body 20 are attached, the bending vibration of the piezoelectric plate or electro-distortion board 10 and the elastic body 20 is applied to the moving shaft. The moving object 40 performs the linear motion. At this time, the displacement principle of the movable body 40 uses a general physical phenomenon as the law of inertia.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention may be easily implemented by those skilled in the art with reference to the accompanying drawings.

2 illustrates a mechanism in which the moving body 40 is mounted and driven on the moving shaft 30. FIG. 3 illustrates an input pulse applied to the piezoelectric substrate or the electrostrictive substrate 10, and the repeated saw tooth pulse is used as the driving pulse.

Although not shown in FIG. 2, it is assumed that a piezoelectric plate or electro-distortion board 10 and an elastic body 20 are installed on the left side of the illustrated moving shaft 30 as described with reference to FIG. 1. When a pulse wave is input as a driving wave, let's look at the movement of the moving body 40 according to the movement of the moving shaft 30.

2 (a) and 3 (a): It is a starting step. The moving body 40 is located at the point of Sa from the moving shaft 30 of the left end.

2 (b) and 3: ab: in the inclined portion of the sawtooth wave in which the voltage in the 1 step section of the sawtooth pulse wave in FIG. 3 is increased, that is, the section in which b is input in the pulse wave a, together with the moving shaft 30 The moving body 40 moves linearly by the size A (Sa = Sb) in the x-axis direction.

2 (c) and 3 (b) -c: The voltage applied to the piezoelectric substrate or electrodistortion substrate becomes zero at the moment when the voltage of the sawtooth pulse wave of FIG. 3 changes from b to c and becomes zero. At this time, the moving shaft 30 of Figure 2 (c) is moved to the left by a distance 2A instantaneously by the restoration of the elastic body. Since the moving shaft 30 moves to the left at a moment, the moving body 40 having the weight is stopped at the position of Sc by the law of inertia, and only the moving shaft 30 moves to the left. (Sc> Sb)

2D and 3C-D: the moving shaft 30 is again moved along with the moving body 40 by a distance of 2A linearly in the x-axis direction. (Sc = Sd)

2 (e) and 3, d-e: b-c have the same type of motion. (Se> Sd)

2 (f) and 3, e-f: c-d have the same type of motion. (Sf = Se)

As described above, the movable body is moved by the law of inertia as well as the elastic action of the elastic body by driving the sawtooth pulse wave input to the piezoelectric substrate or the electrostrictive substrate. This displacement is generated by the piezoelectric or electro-distortion board 10 so that a bending motion occurs in a uni- or bi-morph, ie single- or double-substrate structure, and is transmitted to the moving shaft 30. Displacement occurs continuously. Using this principle, the movable body 40 is moved from the end of the left axis to the end of the right axis.

Using this principle, if the displacement is transmitted to the moving shaft 30 by changing the direction of the saw tooth pulse of FIG. 3, the direction of the moving body 40 is changed to move the moving body 40 to the moving shaft 30. It is possible to control the direction of the moving body 40 to move from the left end of the right end. The invention of the motor is provided on the principle of the law of inertia as specified above.

The basic structure of the present invention for achieving the above object is characterized by consisting of a piezoelectric substrate or electrostrictive substrate 10, the moving body 40, the moving shaft 30, the elastic body (20). In addition, by applying such a basic configuration, the present invention has developed various types of small piezoelectric / electric distortion ultrasonic linear motors, such as three structures presented in the embodiments of the present invention.

4 (a), 4 (b) and 4 (c) show an embodiment of a small piezoelectric / electric distortion linear motor having three types of structures using the basic configuration.

FIG. 4 (a) shows a first embodiment of the present invention, which includes a piezoelectric plate or electrostrictive substrate 10, an elastic body 20, and a moving body 40. The piezoelectric plate or electro-distortion board 10 and the elastic body 20 are unimorphs having a disk shape, and the elastic body 20 is directly without loss of vibration transmitted from the piezoelectric plate or electro-distortion board 10. It is possible if the metal material is excellent in elastic properties having a constant thickness that can be transmitted and operated, in the embodiment of the present invention was manufactured using phosphor bronze. When the moving shaft 30 is directly attached to the elastic body, a protrusion 35 for supporting the moving shaft may be provided. When the piezoelectric / electric warp substrate is a single layer unimorph, as shown in FIG. 3 (a), the piezoelectric or electro-distortion substrate and the moving shaft may be installed on the opposite side of the elastic body, or the moving shaft may be installed on the same side as the piezoelectric substrate or the electro-distortion substrate. will be. The moving shaft may be installed at the center of the piezoelectric substrate or the electrostrictive substrate and the elastic body to obtain the largest displacement, so that the efficiency will be high.

As shown in FIG. 4 (a), the moving shaft may be attached to an elastic body on the opposite side of the attaching surface of the piezoelectric / electric warp substrate, and as shown in FIG. When directly attached to the elastic body, the piezoelectric substrate or the electrostrictive substrate may be attached to an area except for the region to which the moving shaft is attached.

Here, the piezoelectric plate 10 may be used by polarizing in the thickness direction, and vibrates from the outer diameter to the inner diameter or from the inner diameter to the outer diameter of the disk-shaped piezoelectric plate or electrostrictive substrate 10 according to the input tooth pulse wave. This happens, resulting in a unimorph flexion.

In the first embodiment of FIG. 4 (a), a piezoelectric plate or an electrostrictive substrate 10 is attached to one side of the elastic body 20, and a hole is formed in the center of the other side of the elastic body 20. The shaft 30 was attached, and the outer diameter of the elastic body was made larger than that of the piezoelectric substrate or the electrostrictive substrate 10 so that the elastic body could be fixed. The fixed end 25 is installed on the outer side of the elastic body 20, and the fixed end is manufactured to perform a function in which the motor is fixed and installed, and to the vibration of the piezoelectric plate or the electro-distortion board 10. It plays a role to fix the motor itself.

The moving shaft 30 should be about several times lighter than the weight of the bimorph, which is a double structure in which the elastic body 20 and the piezoelectric substrate or electrostrictive substrate 10 are fastened, and the vibration generated from the piezoelectric substrate and the electrostrictive substrate is reduced. It is configured to propagate efficiently and is also manufactured so that the movable body provided on the moving shaft can move on the moving shaft. In the present invention, the hollow shaft was manufactured using the hollow shaft. A saw tooth voltage source U is connected to both electrodes of the piezoelectric substrate or the electrostrictive substrate 10 to input a driving wave.

4 (b) is a second embodiment of the present invention, the motor shown here can improve the life of the motor in a form that can lower the voltage value as a bimorph (bimorph) using two piezoelectric plates or electrostrictive substrates It was made to be. Here, the piezoelectric plate used may be polarized in the thickness direction, and is installed so as to maximize the vibration generated by appropriately adjusting the polarization direction of the piezoelectric plate attached to the upper and lower portions. In addition, the saw tooth pulse (saw tooth pulse) is applied to the upper and lower electrodes of the piezoelectric substrate or the electrostrictive substrate 10 and connected to the elastic body 20 to drive. Even in this case, the piezoelectric plate or electro-distortion board attached to the same side as the moving shaft 30 is manufactured to be attached to an area except for the attachment surface when the moving shaft is attached to the elastic body, and the moving shaft is attached to the piezoelectric plate or electro-distortion board. It may be attached to the top of the substrate to be manufactured.

4 (c) shows a third embodiment of the present invention, in which the motor and the piezoelectric plate or the electro-distortion board are manufactured in the shape of a rectangle rather than a disk. It can be applied to a structure constrained by the size of one direction. The motor is operated by a unimorph (unimorph) having a size of a rectangular shape a x b composed of the elastic body 20 and the piezoelectric substrate or the electrostrictive substrate 10. Even in this case, the bimorph may be manufactured as shown in FIG. 4 (b) and the structure thereof may be manufactured in the same manner as described with reference to FIG. 4 (c).

As such, the shape of the piezoelectric substrate or the electrostrictive substrate and the elastic body may be adjusted to be suitable for the apparatus to which the piezoelectric / electric distortion ultrasonic linear motor is applied, and the present invention may be manufactured in various forms in addition to the circular type or the rectangular type proposed in the present invention. Do.

5 illustrates an embodiment of the movable body 40 mounted on the moving shaft 30. When the movable body 40 is coupled to the elastic body by the waveform applied to the piezoelectric substrate or the electrostrictive substrate to generate a vibration, the vibration is transmitted to the moving shaft, and the movable body moves on the moving shaft so that the piezoelectric substrate or the electrostrictive substrate is moved. This function converts the displacement generated by the vibration into linear movement of the moving object.

The structure of the movable body shown in FIG. 5 is only one embodiment of the present invention, and if the structure can maintain a constant frictional force with the movable shaft on the movable shaft 30 and can be applied to the law of inertia of the present invention with a constant mass ( 40).

Therefore, a metal body having a certain weight or a material having a weight may be used as a moving body made of a single body manufactured to have a constant frictional force in close contact with the moving shaft and in close contact with the moving shaft.

The moving body is configured to surround at least a part of the surface of the moving shaft in close contact with the surface of the moving shaft to maintain the frictional force, and preferably may be manufactured to have a structure to be inserted into the moving shaft. In addition, the movable body 40 has a frictional force and should be manufactured to have a certain weight so that it can be moved by the law of inertia.

As shown in FIG. 5, a metal material including a friction material 42 in direct contact with the moving shaft to maintain a constant friction force, and is formed to surround a portion of the friction material outside the friction material 42, and has a constant mass. The weight member 44 may be formed. A spring 46 may be installed on the outer side of the heavy material to tighten the heavy material by using an elastic spring made to surround the heavy material for firm coupling between the heavy material 44 and the friction material.

As shown in FIG. 5, the moving body may be reconstructed into two semi-cylindrical forms including a friction material at a portion closely contacting the moving shaft and a metal body having a mass formed to surround the outside of the friction material. When installed, it is tightened by the spring.

When the moving body 40 is mounted on the moving shaft 30, it must have an optimized compressive force to indicate the motion of the motor having excellent performance. The spring 46 having a compressive force is installed to impart an optimized compressive force between the mover and the moving shaft 30.

The friction material was reworked using a non-metallic brake material, and the weight material was manufactured using a heavy metal material.

6 shows the operation of the movable body 40 mounted on the moving shaft 30 of the motor and the unimorph or bimorph. The movement of the movement shaft 30 and the movement of the movable body 40 according to the bending motion of the uni-morph or bi-morph (uni-, bi-morph) fixed to both ends is shown. It can be seen that the moving body 40 is moved by the displacement of the uni-morph or bi-morph (uni-, bi-morph).

The compact piezoelectric plate linear motor according to the present invention configured as described above uses a flex motion of a uni or bi-morph including the elastic body 20 and the piezoelectric plate or electro-distortion board 10 as a driving source. In addition, the moving body 40 mounted on the moving shaft 30 is related to the movement of the manufacturing process is simple and easy to apply according to the basic principle, it can provide a small piezoelectric / electrostrictive linear motor with excellent characteristics. The present invention relates to a small piezoelectric / electrical distortion linear motor having excellent thrust compared to the motor size actually applied, and having a high operating speed and stable driving.

Claims (6)

Piezoelectric or electrostrictive substrates with electrodes formed on both sides, An elastic substrate to which the piezoelectric substrate or the electrostrictive substrate is attached to one side or both sides thereof, A moving shaft fixed to a portion of the elastic substrate or the piezoelectric substrate or the electrostrictive substrate attached to the elastic substrate, and formed in a vertical direction of the elastic substrate, and Piezoelectric / electrostrictive ultrasonic linear motor, characterized in that it comprises a movable body made to be movable on the moving shaft. The method of claim 1, The piezoelectric plate is polarized, the piezoelectric / electrostrictive ultrasonic linear motor. The method of claim 2, The moving body is in close contact with the piezoelectric / electrostrictive ultrasonic linear motor, characterized in that formed to surround at least a portion of the moving shaft. The method of claim 3, The moving shaft is a piezoelectric or electrostrictive ultrasonic linear motor, characterized in that for transmitting the vibration of the piezoelectric or electrostrictive substrate with a high efficiency in the shape of a thin circular or square rod. The method according to any one of claims 1 to 4, When the moving shaft is attached to the elastic body, the piezoelectric or electrostrictive ultrasonic linear motor, characterized in that the piezoelectric substrate or the electrostrictive substrate is attached to the region except the place where the moving shaft is attached to the elastic body. The method according to any one of claims 1 to 4, The movable body includes a friction material in close contact with the moving shaft and a heavy material on the outside of the friction material, and includes a spring installed on the outer side of the heavy material in order to compress the friction material and the heavy material on the moving shaft, and the movable body is moved. A piezoelectric / electric distortion ultrasonic linear motor, characterized in that it is made to be inserted into the shaft.