JP2007151373A - Ultrasonic linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylindrical actuator which generates powerful torque at a low voltage of several volts and whose diameter and length are several millimeters. <P>SOLUTION: Torque transmission circular rings of a rotor 200 are pressure-welded to both end faces of a cylindrical revolver 100, whose axial length is shorter than the diameter. When the rotor 200 is supported by flotation, a working fulcrum of the pressurized force rotates with the rotor, and friction loss can be avoided. This mechanism may be expressed as an active bearing generating torque, and thus attains non-eccentric rotation, super-precision and low loss. By using this means, an active mirror cylinder which automatically extends and contracts is obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  Electromagnetic motors have greatly contributed to the world as rotating machines for a century. Technically, it features electromagnetic power as a power source, non-contact high-speed rotation, easy input of powerful energy, power with good controllability, and extremely high input / output efficiency. As a representative of high-power rotating machines, it has supported industries that have made great strides in the 20th century. However, at the beginning of the 21st century, the technological development goals were switched from intelligent work to more intelligent, and from larger to smaller and higher-definition routes, and began to aim at nanotechnology. If the electromagnetic motor is made thinner, the torque will be extremely small and the torque will be extremely small. In addition, the winding structure will be damaged and the efficiency will suddenly deteriorate below 1 watt. It is becoming unsuitable for the development route.

  This technical goal is that our living environment relies on more electronic information, and as the amount of information increases, high-speed processing is required and eventually online processing is required. Taking a camera as an example, optical technology mainly consisting of lenses was developed over a long period of time, requiring high definition, high image quality, artisticity, and realism, even though it was large and heavy. The emphasis was on recording rather than the passage of time that required development and printing for video reproduction. Even if a video appeared, the same time as imaging was required for video playback, so the needs remained the same. The situation changed completely with the appearance of digital cameras. Reproduction / recording has become online, artisticity has been neglected, and functions as portable information terminals have begun to be emphasized. This trend is becoming stronger and more powerful, and at the same time, in addition to lightweight compactness and ease of use, not only high-definition and high-quality images, but also online capabilities such as simultaneous transfer are increasingly required. ing.

  In the process of progressing such light, thin, small, and high functionality, the development of an actuator that meets the needs has become one technology bottleneck. The mainstream of the actuator is an electromagnetic motor. However, if the size is reduced, the output per weight, that is, the power density is reduced to several tens of watts / kg or less, the rotation speed is higher than necessary, the torque is reduced to less than necessary, and there is no positioning holding force. The generation of electromagnetic noise is an obstacle. Therefore, the hurdles for developing actuators that meet future needs have increased, and difficulties have been anticipated, so alternative actuator technologies have been craved.

  An ultrasonic motor can be cited as the most promising candidate to replace an electromagnetic motor for developing a new actuator. First of all, let us describe the principle of ultrasonic motors as background technology according to the history of development. The present inventor causes a piezoelectric deformation of a piezoelectric element having a circular shape, such as a piezoelectric disc, ring, cylinder or tube, to be asymmetrically arranged with respect to the central axis, asymmetrically with respect to the central axis. An electrostrictive trochanter characterized by the above, for example, an ultrasonic rotating vibrator (Japanese Patent No. 2529233), a quadrupole rotating ultrasonic vibrator (Japanese Patent Application No. 6211375), a cylindrical ultrasonic quadrupole rotating vibrator (Japanese Patent Application No. Akira). 62-71594), a pipe-shaped electrostrictive revolution rotator and a motor (Japanese Patent Application No. 1-114249) have been proposed. These circular piezoelectric elements are configured such that regions divided into two or four by a diameter passing through the central axis of the circle can be excited independently in the thickness direction, and the induced polarization of each region is relative to the central axis. When excited at the frequency of the natural vibration of the asymmetric mode, it was found that a powerful revolution torque was resonantly amplified, and the above patent was filed as an electrostrictive revolution rotator.

  In the original electrostrictive revolving rotator, attention was paid to the phenomenon that the revolving torque was generated in the plane perpendicular to the central axis of the circle, and the mode perpendicular to the diameter could not be used. After that, when the cylindrical electrostrictive revolution element is asymmetrically excited, a mode rotation resonance state in which all radial, circumferential, and axial vibration modes are combined is obtained, and three-dimensional revolution torque is generated on all surfaces of the cylinder. As a result, a patent application (Japanese Patent Application No. 9-114126) was filed under the names of the ultrasonic 3D torque resonator and the actuator.

  The electrostrictive rotator is shaped like a disc or cylinder, polarization configuration such as symmetric polarization or asymmetric polarization, electrode configuration such as non-divided, 2-divided, 4-divided or common electrode, single phase or multi-phase excitation It has been developed so that the most suitable revolution torque can be obtained for various applications by selecting the combination of the type of power source and the excitation mode such as series excitation or parallel excitation. Conventionally, a one-dimensional linear vibration is generated in a uniform piezoelectric vibrator, and the torque cannot be resonantly amplified by the piezoelectric vibrator. To generate torque, the vibration of the elliptical trajectory is supported through auxiliary means such as changing the standing wave vibration of the bending vibrator into a traveling wave by electrically shifting the phase, or combining a mode coupler with bending vibration. I had to change it. In an electrostrictive revolving rotator, the revolution torque associated with mode rotation essentially resonates. As a result, not only can direct torque be excited even with a single-phase voltage, but the vibration Q is high and the resonance admittance is large. It has the feature that it can generate powerful torque with voltage.

  As described above, the ultrasonic motor has an output density that is two orders of magnitude greater than that of the electromagnetic type, can output an extremely strong torque with an efficiency exceeding 30%, and operates repeatedly in sub-micron steps at maximum. It is suitable for miniaturization and high definition, and its high holding power is a candidate that can be greatly evaluated as a high precision positioning actuator rather than a motor. In conventional electromagnetic motors, rotational torque generated in the rotor is extracted by coupling the rotating shaft of the load to the rotating shaft of the rotor, and the shaft vibration that occurs parasitically with the rotation of the rotor causes eccentric rotation. It is ineligible for use in the technical field aiming for. On the other hand, since the electrostrictive revolution element does not rotate during the operation of generating revolution torque, the rotor can be supported in a fixed state, and since the rotor is always pressed against the electrostrictive revolution element, If the holding force is strong and the way of viewing is changed, it can be seen as a bearing that generates torque on the peripheral surface, that is, an active bearing, and the load can be driven in ultra fine state with no eccentricity.

  In order to use the powerful revolution torque generated on the end face of the cylindrical electrostrictive revolution rotor, the rotor may be pressed against the end face. As a simple means, it is only necessary to hold the disc / annular rotor coaxially with the electrostrictive revolution rotor so as to freely rotate and press-contact with the end face, but in this case the fulcrum of the pressing force is the holding portion of the rotor, That is, since it becomes a fixed part, there is a disadvantage that friction occurs when the rotor rotates. It has been found that this disadvantage can be solved by adopting a structure in which a common rotator is sandwiched between two annular rotors. That is, the strong 3D torque generated on both end faces of the revolution rotator cylinder has components in the same direction in both end faces along the circumference along the circumference, and both end faces repel each other in the axial direction. Since it has a component of the reverse phase to be sucked, it has been found that when a rotor is pressure-bonded to each end face, both the levitation force repelling from the end face and a strong torque rotating in the same direction are both received. By passing the two annular rotors and the shaft passing through the inner diameter of the revolving rotator and pressing the two rotators against the end face of the revolving rotator, the applied pressure is balanced with the levitation force due to the revolving torque, and the fulcrum of action The structure that puts on the shaft was invented. In this structure, since the rotor and the shaft rotate integrally, the rotation of the shaft is supported by the electrostrictive revolution rotor, and the fulcrum of the pressure contact force can be separated from the fixed portion, and the friction accompanying the rotation of the rotor is reduced. This is a mechanism that can be avoided and can also be called an active bearing, and the fact that the bearing can naturally be expected to be eccentrically rotated means that the present invention has innovated the motor technology.

  It is an object of the present invention to pioneer a means for accurately moving a load to a desired position. For example, a precise movement positioning actuator that adjusts the focus of an image by moving a lens of an optical barrel. Is to realize. In addition, in the case of an optical lens barrel, an object to be pioneered is an active lens barrel that can be automatically expanded and contracted rather than operated by an external driver. In other words, the realization of an actuator that combines compactness, simplicity, and precision of operation. In this case, the lens barrel must be a stator of the actuator, and the lens must be a mover.

  In order to solve this problem, there is a demand for a linear actuator that is smaller, lighter, driven at lower voltage, lower power, higher precision, higher performance, and lower cost. As described above, when the electromagnetic motor is downsized, the torque and efficiency become extremely low, and the vibration of the shaft accompanying high-speed rotation causes eccentric rotation. The lack of holding force and the like are not suitable for the above-mentioned actuator development candidates that are small and require an ultra-precision positioning function. However, the stepping motor is a means that does not change the precision positioning, but it is extremely difficult to realize the fine steps required by the problem.

  On the other hand, ultrasonic actuators have high output density, so they are suitable for miniaturization and weight reduction. However, traveling wave motors composed of composite vibrators have a large output torque, but have a high drive voltage. . In addition, the electrostrictive rotator type motor with asymmetrical excitation of a long and narrow cylinder is a so-called counter-rotation mode in which the bending mode and bending mode of the long and narrow cylinder are combined. It is difficult to adopt to solve the problem. In order to increase the rotational torque, there is a composite resonator using a metal cylinder as a vibrator. However, the composite vibrator has a drawback that the Q is low and the drive voltage is high. In order to avoid this drawback, the piezoelectric element has been developed as a thin motor by reducing the thickness of the piezoelectric element and reducing the diameter of the vibrator to about 1 mm. Although this motor will be applied to some applications, it cannot be used for the active lens barrel.

  As can be seen from the above description, the first issue is the development of a cylindrical actuator with a low voltage of several volts and a diameter and length of several millimeters that generates a powerful torque. The second problem is the development of a means for converting into linear motion because the actuator of the first problem can be developed and the output cannot be used to drive the telescopic operation of the lens barrel when the output is rotational torque. The third problem is high precision and thinning of the actuator.

  Here, the matter that needs to be confirmed is that rotation and linear torque are generated on the inner peripheral surface of the 3D torque resonator. Exercise is possible. This movement is a jumping toward the vibration node, and it moves as if supported by a stretched spring set at the position of the node. It is not suitable for the actuator.

  First, an actuator for solving the first problem must have a cylindrical shape capable of incorporating a lens. The electrostrictive revolution rotor that generates the 3D revolution torque introduced in [Background Art] is a perfect means to satisfy this condition. In particular, when the shaft length is shorter than the diameter, the 3D revolution is generated on both end faces of the cylinder. The rotor supported by the revolving torque gives powerful rotation torque and no eccentricity and high-definition step rotation, and the rotor is supported without rotational friction. Yes, satisfy all the third issue. What remains is a means for converting the second rotational torque into linear motion. Constituent elements of the means for satisfying this problem are: (1) a driving force generating element for generating a revolving torque on the end face, inner peripheral surface or both of the cylindrical electrostrictive revolving element, and (2) a pressure contact with the end face of the driving force generating element. In order to transmit the rotational force to the moving element while rotating together with the circular ring that receives the revolution torque, the cylindrical rotor that can interpolate the moving element, (3) coaxial with the rotor (4) A moving element having a cylindrical or columnar shape provided with a screw male screw on at least a part of its outer circumference, and (4) transmitting the rotational force and simultaneously moving the moving element linearly in parallel with the axis. Slide key for assisting or preventing linear movement in the axial direction by preventing the rotation of the moving element, and (5) Supporting and supporting the reaction of the rotating torque of the rotor, and simultaneously supplying power Terminal Consists of a housing that is fixedly supported.

  The means for solving the problem 2 depends on the technical content of the problem, that is, whether the movement mode of the moving element (2) is selected from linear motion with rotation or linear motion without rotation. Different types of combinations. When rotation is involved, the slide key (4) is set between the (2) mover and the (3) rotor so that the rotation of both does not deviate and the shaft rotates while the mover rotates. It is used to perform the function of linear motion in parallel. In the case of linear movement only, the slide key (4) is set between the slider (2) and the housing (5) or an external fixed part to prevent the movement of the slider. Then, a linear motion function is given to the moving element. Note that the means for solving the problem is that the stator is sandwich-welded with the above-mentioned annular ring and the annular part of the rotor as a pair, so that the fulcrum of the pressing force is separated from the fixed object, placed on the rotor itself, and driven. The solution of the present invention is different in that the configuration of the solution means is different depending on whether it is configured to use the torque on both ends of the force generating element at the same time or only the torque on one end surface with a single annular transducer. Since the description of the means is complicated, details will be described in (embodiment) according to the structure of the means.

  As for the cylindrical piezoelectric resonator which is an essential condition of the actuator of the present invention, as a result of repeating an enormous number of experiments using various samples having different combinations of outer diameter, cylindrical thickness, and axial length ratio, attention is paid. I found a fact that should be. In a normal piezoelectric resonator, a sharp resonance characteristic with the highest resonance amplification factor is obtained from a so-called fundamental resonance frequency having the lowest natural vibration frequency. This is also the case with long-axis cylinders having a longer axial length than the circumferential length. On the other hand, in the short axis cylindrical piezoelectric resonator used in the present invention, the axial mode with a considerably higher frequency is sharper with a much higher resonance amplification factor than the fundamental resonance mode related to the vibration in the circumferential direction. It was found that the resonance characteristic was obtained and the resonance admittance became an incredibly large value. A large admittance means that a large power can be input, which is an essential condition as a power source.

  Even in a 3D resonator subject to asymmetric excitation, the strongest torque can be obtained in the axial resonance mode, which is the second resonance frequency. A powerful 3D torque is generated. This 3D torque has a component in the same direction in both end surfaces with respect to the rotation axis along the circumference in the end face, and in the axial direction, the opposite end components repel or attract each other in the axial direction. At the same time, the rotor can be supported friction-free by the levitation force in the axial direction, and friction caused by the rotation of the rotor can be avoided. This means that the present invention encouraged innovation in motor technology.

  By adopting a structure that transmits the powerful rotational torque generated on the end face of the cylindrical electrostrictive revolution element to the mover and converts it to linear torque via the screw screw of the mover, a cylindrical shaft or cylindrical shape, etc. The actuator that moves the slider in a straight line, powerfully and with high precision could be realized. As a result, for example, when the movable element is an optical lens barrel, it is possible to realize a lens barrel that is compact enough to be named as an active lens barrel, and that has the simplest structure that operates automatically with high precision, giving it to the application field. The technical and industrial effects will be immeasurable.

  (First embodiment)

  As an embodiment of the ultrasonic linear actuator according to the present invention, means for giving a linear motion to the moving element 4 using the rotational torque generated on one end face of the cylindrical electrostrictive revolution element 1 shown in FIG. The first means for moving the child in the axial direction at the same time as the rotation and the second means for making the linear movement without the rotation of the moving member will be described. The components of the first means and the second means are the same, and are shown in FIGS. 2 (a) and 2 (b). The cylindrical electrostrictive revolution rotator 1 has drive electrodes 11, 12, 13, 14 divided into four equal parts along the outer peripheral surface and a common electrode 15 applied to the entire inner peripheral surface. The moving element 4 to which the screw screw 45 is applied is incorporated. In the present embodiment, the optical barrel 4 in which lenses 41 and 42 are housed in the moving element is used.

  A screw screw 45 is provided on the outer peripheral surface of the cylinder of the movable element 4. Grooves 461 and 462 that cross the screw are formed at two locations obtained by dividing the peripheral surface of the screw into two equal parts. As shown in FIG. 2 (a), an electrostrictive revolving rotator 1 having a built-in moving element 4 is inserted from the inlet of the housing 5, pressed against the wave ring spring 31 at the back, and the rotor 2 or 3, bearing from the inlet side. When the housing lid (stator) 6 is lightly press-fitted and fitted to the specified position with the balls 56 being stacked, the ring spring 31 presses the rotor 2 or 3 against the electrostrictive revolution rotator 1 with the optimum pressure. . Since the rotor is supported by the stator 6 through bearings, the electrostrictive revolution rotator 1 is excited by the voltage applied to the terminals 51, 52, 53, 54 through the lead wires 71, 72, 73, 74, and the end face When a revolution torque is generated, the rotation occurs.

  Here, in the first means, a ring-shaped rotor 2 and a stator 6 are used. The inner diameter of the rotor 2 is slightly larger than the screw screw 45 of the moving element 4 and does not come into contact with the screw. However, protrusions 261 and 262 extending inwardly to the diameter are provided at two places divided by the diameter, and the screw It is set in the grooves 461 and 462 of the screw. A female screw 65 that meshes with a male screw 45 on the outer peripheral surface of the moving element is applied to the inner peripheral surface of the lid (stator) 6 of the housing, and is engaged with the male screw 45. The protrusion 261 is a so-called key, and transmits the rotation of the rotor 2 to the moving element 4. When the moving element 4 rotates, the screw screw 45 is engaged with the female screw 65 of the stator 6. In this way, a linear motion is made to move forward or return in the axial direction while rotating.

    In the first means, the moving element performs linear motion with rotation. Here, the second means in which the moving element performs linear motion without rotation will be described with reference to FIG. As in the first means, the electrostrictive revolution rotator 1 with the built-in moving element 4 is inserted from the inlet of the housing 5 and pressed against the wave ring spring 31 at the back, and the rotor 3 and the bearing ball 56 are overlapped from the inlet side. In this state, when the lid, that is, the stator 6 is lightly press-fitted and fitted to the specified position, the ring spring 31 presses the rotor 3 against the electrostrictive revolving element 1 with the optimum pressure. Since the rotor 3 is supported by the stator 6 through bearings, the electrostrictive revolving rotor 1 is excited by the voltage applied to the terminals 51, 52, 53, and 54 via the lead wires 71, 72, 73, and 74. When revolving torque is generated on the end face, it rotates.

Here, a female screw 25 is provided on the inner peripheral surface of the ring-shaped rotor 3, and is engaged with a male screw 45 of the moving element 4. The key grooves 461 and 462 of the moving element 4 are respectively applied to the stator 6. When the projected protrusions 61 and 62 are set, the movable element 4 cannot rotate but can slide freely. Since the male screw 45 of the moving element 4 meshes with the female screw 25 of the rotor 3, a revolving torque is excited on the end face of the electrostrictive revolving rotor 1, and when the rotor 3 rotates clockwise, the male screw 25 is rotated by the rotation of the female screw 25. When the moving element 4 is pushed out through 45 and rotates counterclockwise, it moves linearly so as to be drawn inside the revolving element. As described above, the first means is rotated and the second means is not rotated, but both of them can linearly drive the lens barrel 4 as a moving element in the axial direction.
(Second Embodiment)

  The rotor mechanism, which is the second subject of the present invention, is composed of two rings fitted on both ends of a pipe inserted and penetrated into a cylindrical electrostrictive revolution rotor generating rotational torque on both end faces. Two notable advantages were obtained by using a sandwich pressure weld configuration. First, as in the first embodiment, the torque generated on both end faces of the rotator is not used on one side, but both are used simultaneously, so that a stronger torque can be obtained. The second advantage is that, in the first embodiment, since the fulcrum of the force for pressing the rotor 2 against the revolving element 1 is placed on the stator 6, contrary to the fact that friction avoiding means such as a ball bearing 56 is required, 2 By adopting a configuration in which the revolving rotator is sandwiched between the annular parts, it is possible to apply a crimping force between the annular parts that rotate integrally with the rotor, and the speed between the point of application of the crimping force and the fulcrum. The generation of friction due to the difference could be avoided. The two advantages described above are extremely important technologies in terms of actuator configuration. Hereinafter, the embodiment will be described in detail with reference to FIG.

  In the present embodiment as well, as in the first embodiment, the moving means using the lens barrel rotates in the axial direction and the second means moves in the axial direction without rotating. There is a means. In both cases, the basic mechanism for torque generation is a structure in which two rings fitted on both ends of a pipe inserted into and penetrated into a cylindrical electrostrictive revolving rotator that generates rotational torque on both end faces and sandwiched by the reciprocating element is sandwiched. is there. In the first means, a slider inserted in the rotor is engaged with the rotor with a key so that both of them can slide in the axial direction while rotating integrally, and a screw provided on the outer peripheral surface of the slider. By fitting the screw into the female screw of the stator set coaxially with the revolving element, linear movement with rotation in which the moving element rotates linearly is possible. On the other hand, in the second means, the inner surface of the rotor is provided with a female screw and engaged with a mover having an outer peripheral surface provided with a male screw. When the mover is prevented from rotating, it performs linear motion without rotation. The operation principle of both the first means and the second means is the same as that of the first embodiment, and overlaps. Therefore, the structure of the second means will be described specifically by taking the second means as an example.

Here, an embodiment of an elongated linear actuator will be described.
As shown in FIG. 3, a rotor 20 having a cylindrical portion that can be completely inserted is set on the electrostrictive revolution rotator 10 in which torque is generated at both end faces. Since one end surface of the rotor 20 has a flange 201, when the coil spring 30 is first passed through and then the free ring 202 and then the electrostrictive revolving element 10 are pressed to the flange, the other end of the rotor 20 faces the face. Therefore, the fixing ring 203 is press-fitted into the tip until it becomes flush. In this state, the coil spring 30 presses the free ring 202 against the end face of the revolving rotator, so that the optimum pressure is applied to the revolving rotator in a state where the revolving rotator 10 is sandwiched between the fixing ring 203 and the free ring 202 as a fulcrum. The dimensions of each part of the rotor are designed to work. Therefore, when the revolving element is excited in this state, a strong revolving torque is generated, and the rotor 20 rotates powerfully.

  At this stage, since the basic function of the electrostrictive revolution rotator actuator is completed, the lens barrel as a load is mounted as the mover 40. The mover 40 is provided with a screw screw 405 on the outer periphery, and the remaining portion 402 is a cylinder that is one step thinner than the inner diameter of the rotor 20. The surface is smoothly finished, and the vicinity of the tip of the mover 40 from the vicinity that contacts one end of the screw screw 405. Until then, the keyway 406 is carved in the direction parallel to the axis. When the screw screw 405 of the moving element 40 is inserted along the screw screw 205 of the rotor 20 and set, the moving element 40 is inserted smoothly and smoothly into the inner periphery of the cylinder 20 of the rotor. The mover 40 is smoothly inserted along the screw screw while being inserted in the cylinder 20 of the rotor. When the rotor is rotating, if the rotor is prevented from rotating, the mover moves in the axial direction. Performs linear motion smoothly. The rotor into which the moving element is inserted is placed in the hollow hole 507 of the prismatic housing 50 shown in FIG. 4, and the screw screw 405 of the moving element is fitted into the screw screw 505 at the back end, so Are fixed and supported by the four power terminals 501, 502, 503, and 504, and the lid 60 through which the end of the movable cylinder 402 is passed through the center hole is fixed to the wing by the set screws 65, 66, 67, and 68. Finally, the pin-shaped key 506 attached to the housing 50 is set in the key groove 406 of the moving element 40, and the ultrasonic linear actuator 80 that fully utilizes the torque at both ends of the revolving element is completed.

  Four channels of the four-phase switching voltage obtained by sequentially switching the DC voltage at the second natural vibration of the electrostrictive revolving element 10, that is, four times the axial resonating resonance frequency are power terminals 501 and 502 of the ultrasonic linear actuator 80. , 503, and 504, the resonating resonance state of the electrostrictive rotator 10 is excited. When the rotor 20 is rotated by receiving the revolving torque generated at both end faces of the electrostrictive revolving element 10, the moving element 40 whose rotation is blocked by the pin-like key 506 is caused by the action of the screw screw 405, and FIG. A smooth linear motion in the axial direction reciprocating between the positions indicated by the dotted line and the solid line in FIG.

Although the moving distance of the moving element is proportional to the time during which the voltage is applied, the maximum circumferential speed n of the rotor shows a saturation value of about 0.5 m / s. ₀ is
n ₀ = 0.5 / πD rps (1)
The linear velocity v depends on the pitch p of the screw screw 405,
v = pn (2)
It becomes. When the diameter D of the slider is 3.5 mm and the pitch p is 0.3 mm, the linear velocity v is
v = 0.5p / πD
Therefore, the maximum value is 13.6 mm / s. Here, if the electrostrictive revolution element has an outer diameter of 55 mm, an inner diameter of 3.5 mm, and a height of 3.5 mm, the revolution resonance frequency is about 460 kHz, and the linear velocity v of the slider is a calculated value of 30 nm per cycle of the excitation frequency. Indicates. This value is an ultra-fine value that is absorbed by the male screw and the female screw in a normal screw, and the ultrasonic linear actuator 80 can control the amount of movement with an applied voltage in an ultra-high manner. It can be said that it is a fine linear actuator.
(Third embodiment)

  In the first embodiment, the configuration and operation principle of the rotation / linear moving element using the torque of one end face and the linear moving element not rotating are exemplified among the torques generated on both end faces of the electrostrictive revolution element. In the second embodiment, based on the configuration and operation principle of the rotation / linear movement element exemplified in the first embodiment and the linear movement element that does not involve rotation, the torque generated at both end faces of the electrostrictive revolution rotator is determined. A more advanced means of using both simultaneously is illustrated. In the second embodiment, since the coil spring is used as the pressurizing spring and the movement distance of the lens barrel is further increased, the axial length is significantly longer than that of the mechanism exemplified in the first embodiment. . In recent practical use, there is a craving for a compact structure with a shorter axial length and an active lens barrel (automatic lens barrel) consisting of a linear actuator that only moves linearly without rotation. This form is disclosed in FIG.

  The rotor 200 having a cylindrical portion that can be inserted into the electrostrictive revolution rotator 100 in which torque is generated on the same end faces as described above is set. One end surface of the rotor 200 is provided with a flange 201, and a screw female screw 205 is provided on the inner peripheral surface. First, when the wave ring spring 31 is passed through the rotor 200 and then pressed to the flange 201 through the electrostrictive revolving rotator 100 next to the free ring 202, the other end of the rotor 200 comes out, so that a fixed ring is attached to the tip of the ring. Press-fit 203 until it is flush. In this state, the wave ring spring 31 presses the free ring 202 against the end face of the revolving rotator, so that the optimum pressure is applied to the revolving rotator in a state where the revolving rotator 100 is sandwiched between the fixed ring 203 and the free ring 202. The dimensions of each part of the rotor are designed to work. Therefore, when the revolving element is excited in this state, a strong revolving torque is generated, and the rotor rotates powerfully together with the pressurizing spring 31. Here, the applied pressure is supported by the rotor, and the rotor rotates while being supported by the strong buoyancy of the end face torque of the electrostrictive revolution rotor that is fixedly supported. It is the greatest advantage of the present invention that there is no friction force generated in the motor and that the rotation loss is extremely low.

The embodiment of the drive unit of the ultrasonic linear actuator has been illustrated above.
Next, the lens barrel 40 having a screw male screw 405 aligned with the screw female screw 205 of the rotor on the outer peripheral surface is set in the optical axis direction. This whole is inserted until it hits the step of the electrostrictive revolution rotator receiving portion at the back of the hole of the hole 500 in the shape of the perforated die, and the power terminals 501 and 502 applied to the four parallels to the optical axis of the housing. , 503, 504 are fixedly supported. Next, after setting the key pins 601, 602, 603, 604 of the stator 600 corresponding to the lid of the housing in the key grooves 461, 462, 463, 464 of the lens barrel, the four screws 66, 67 are set. , 68, 69, the ultrasonic linear actuator according to the third embodiment of the present invention is completed. When excitation power is connected to the four lead wires 701, 702, 703, and 704, the lens barrel quickly expands and contracts according to the control signal, the lens focus moves to a predetermined position, and the focus of the image is increased. It can be finely matched.

An active lens barrel using an ultrasonic linear actuator constructed in this way can be used for autofocus and autozoom of the optical system, simplifying the mechanism, enabling high-definition, high-speed, control, and a firm stop position. Therefore, it is urgently adopted for mobile phone cameras and the like.
(Fourth embodiment)

  Although the aforementioned actuators have been urgently adopted for mobile phone cameras, etc., the devices used in this field are coexisting with high performance and light and thin, and the above actuators are naturally However, further thinning is desired. In this case, the thinning means to reduce the optical axis length of the active lens barrel, but the axial length of the electrostrictive revolution rotator needs to have a predetermined dimension, and the wrinkle is directed to the pressurizing spring. In the embodiment, a wave ring spring is adopted as the thinnest spring. To make it thinner, the spring thickness would have to be zero. Here we propose a countermeasure.

  In other words, by using a coil spring inscribed in the revolution cylinder or an elastic pipe having a spring action equivalent to this and a screw screw function, the series arrangement with the revolution element is switched to a parallel arrangement, thereby achieving a reduction in thickness. . For example, if the coil spring is inscribed in the revolution rotator cylinder, the ring is inserted from both ends, and the revolution rotator is sandwiched and tightened, the coil spring can be rotated strongly. When a cylindrical slider with a screw screw on the outer periphery is screwed into a screw screw on the inner periphery of the coil spring, if the rotation is prevented without hindering the movement of the slider in the axial direction, the slider is rotated. Unaccompanied linear motion occurs. However, in a normal coil spring, the spring is stretched and the pitch is slightly deviated from the screw of the moving member due to the reaction caused by pressurizing the ring and applying pressure, so that it does not move smoothly. Here, an embodiment that solves this point will be described.

  A rotor 2000 having a cylindrical portion that can be inserted into the electrostrictive revolution rotator 1000 in which torque is generated on the same end faces as described above is set. One end face of the rotor 2000 is provided with a flange 2001, and the cylinder of the main body is made up of three portions 2001, 2008, and 2004. First of all, a screw female screw 2005 is applied to the inner peripheral surface of the flange 2001, and the inner diameter of the subsequent cylindrical central part is increased. A screw-shaped slit 2008 is applied to the thin cylindrical part, and a strong extension spring is formed. It has become. The end 2004 is a uniform cylinder without a slit, and the outer peripheral surface is precisely machined to a predetermined diameter. The end 2004 is inserted into the electrostrictive revolution rotator 1000 and protrudes from the other end. Press-fit 2003 until it is flush. In this state, the slit portion 2008 functions as a spring having a predetermined strength so that the electrostrictive revolution trochanter 1000 is sandwiched between the fixing ring and the flange 2001 so that the optimum pressure is applied to the revolution rotator. The dimensions of each part of the rotor are designed. Therefore, when the revolving element is excited in this state, a strong revolving torque is generated, and the rotor rotates powerfully.

Here, since the applied pressure is supported by the rotor and the rotor rotates while being supported by the strong end face torque of the electrostrictive revolution rotor fixedly supported, the rotational friction loss does not exist as in the previous example. In addition, in the present embodiment, the size of the pressurizing spring can be excluded from the thickness component of the actuator and the thickness can be reduced. Needless to say, even if the slit portion of the rotor extends and functions as a spring, the female screw 2005 portion without the slit is not affected at all, and the screw meshes smoothly so that an accurate linear motion can be realized. It was. This is because the housing is the same as in the third embodiment and the manner of operation is the same. The description is omitted to avoid duplication.
(Fifth embodiment)

  The actuators mentioned above have been urgently adopted for mobile phone cameras, etc., and thinning is desired, so a solution to give the rotor a spring function has been presented, but the mechanism becomes complicated and the cost increases. The fear of connecting came out. In search of a way to simplify the components and reduce costs, we developed an actuator that directly drives the lens barrel, eliminating the rotor. In this method, the lens barrel is directly driven by the torque generated on the surface of the revolution rotator cylinder. In order to use the torque generated in the revolving rotator, the rotor ring portions 22, 202, 23, and 203 must be brought into pressure contact with the torque generating surface as described above, but this pressurizing mechanism is complicated. This was also a factor in the cost increase.

  Here, as a solution, first, screw screws were applied to the inner peripheral surface of the reciprocator, and the lens barrel with the screw screws matching the outer periphery was directly driven to confirm the possibility of linear motion with rotation. . The problem is that the work of threading the inner peripheral surface of the ceramic cylinder is grinding by tapping, which takes time. Therefore, the problem was solved by joining a thin cylinder with a screw thread on the inner peripheral surface to the rotator. If a lens barrel having a screw screw on its outer peripheral surface can be rotated, it can be introduced into the female screw of the stator and changed to a linear motion with rotation. Although this method has the disadvantage that linear motion without rotation is not possible, it is notable for its simple and compact structure. Since the mechanism for converting to linear motion has been described in the above-described embodiment, it will be omitted, and the mechanism of the rotation drive unit will be described in detail below.

  As shown in FIG. 7A, a thin cylinder 2010 having a thickness capable of being inserted into the electrostrictive revolution trochanter 1000 and having a screw screw 2005 on the inner peripheral surface was bonded to the common electrode of the revolution rotator. Thus, the torque generating element is completed, and when the lens barrel 400 of (c) is introduced and set in the housing, an actuator that linearly moves along the optical axis while the barrel rotates is completed. In this structure, a composite resonator with a thin cylinder is formed, and the Q is lowered. Therefore, if a high voltage can be applied, a strong torque can be output.

  Although it is possible to increase the screw screw distance by sticking to the common electrode, the end face torque is stronger in any case, so in (b), thin cylinders 2011 and 2012 are attached to both the inner and outer peripheral surfaces. Although both applied torques were utilized, the thin cylinder was divided into two parts, 2011 and 2012, in order to prevent the resonator from being restrained and the Q from being lowered. Since both the figures (a) and (b) use a long thin-walled cylinder, the distance between the screw screws can be increased, and in the case of a short lens barrel, the moving stroke can be increased.

  In order to drive at a low voltage by using a strong end face torque, a ring with a female thread was attached to only one end face as shown in FIGS. 7 (c) and 7 (d) to avoid lowering Q. . Since the ring is thin, the number of screw threads is small, but when the lens barrel is long as shown in (c) 400 and (f) 401 and there are many threads, the stroke can be made sufficiently long. A zoom mechanism could be configured in combination with a lens barrel that can be inserted and fixed to the revolving trochanter as in 605 of (f).

  As described above, the ultrasonic linear actuator according to the present invention uses a unique cylindrical element that generates a three-dimensional revolution torque by asymmetric excitation among electrostrictive revolution elements capable of exciting a reversible rotational torque even with a single-phase AC voltage. In the case of a revolving element that is a drive element, and in particular the axial length of the cylinder is shorter than the outer diameter length, a strong torque is generated on both end faces of the cylinder. We found that it is like a sandwich with a heel through a pipe with both ends, and when it is crimped to the revolving torque, both heels simultaneously receive the rotational torque in the same direction, so that they are integrated with the pipe and rotate strongly. The fulcrum of the pressure applied to press the heel against the torque generating surface is placed on the rotor, the speed difference between the heel and the fulcrum disappears, and the rotor is a revolving rotator that generates torque, in other words an active bearing that supports friction free it can. This effect is the same in the case of the torque generating element in which the revolution element and the female screw are integrated. Thus, first, an eccentric, high-definition, high-precision, low-voltage drive, and low-power rotation mechanism was realized. Since this rotation mechanism can be configured as a hollow cylinder, an internal thread is provided on the inner peripheral surface, and a movable element, for example, an optical lens barrel, provided with an external thread aligned therewith is inserted and moved freely along the axis, but does not rotate. If supported in this way, the lens barrel, that is, the moving element can move linearly as the rotor rotates, so that a linear actuator can be provided with a simple structure, ultra-precision, and low drive loss. did it. This ultrasonic linear actuator is based not only on mobile phone cameras, but also on small cameras such as digital cameras and video cameras, small cameras for crime prevention, surveillance and in-vehicle use, telescopes, optical devices such as microscopes, medical endoscopes, etc. Since it can be used for mirrors and catheters, it can be expected to contribute to a wide range of fields without limitation.

These are explanatory drawings of the rotation / linear conversion mechanism of the actuator according to the present invention. FIG. 2 is a diagram illustrating the principle mechanism of a rotary / linear mover (a) and a linear mover (b) that does not rotate. Is a configuration diagram of an elongated linear actuator. FIG. 3 is an explanatory view of the structure and operation of a non-rotating and telescopic active lens barrel using an elongated linear actuator. The actuator structure figure (a) of a thin automatic lens-barrel and housing accommodation explanatory drawing. Fig. 4 is a structural explanatory view of a linear actuator which is made thinner by giving the rotor a spring property. FIG. 3 is a configuration explanatory view of a torque generating element in which a ring or thin cylinder provided with a screw female screw is fixed and integrated on an end surface or an inner peripheral surface of an electrostrictive revolution rotator.

Explanation of symbols

1, 10, 100, 1000: Cylindrical electrostrictive trochanter (torque generating element)
11, 12, 13, 14: drive electrode, 15: common electrode 2, 3, 20, 200, 2000: rotor 21, 201, 2001: rotor buttock, 22, 202: free rotor ring,
23, 203, 2003: fixing ring of the rotor, 2004: fixing ring set part 25, 205, 2005: screw screw (female screw) of the rotor cylinder,
261, 262: Rotor protrusion (key)
2008: Slit for imparting a telescopic spring mechanism to the rotor cylinder 30: Coil spring, 31: Ring-shaped wave spring 4, 40: Mover (or lens barrel), 41, 42, 43: Lens 402: Mover Cylindrical part of
45, 405: Screw screw (male screw) of the mover,
46, 406, 461, 462, 463, 464: mover keyway 5, 50, 500: housing, 506: pin pin key of housing,
507: Housing hollow holes 51, 52, 53, 54, 501, 502, 503, 504: Power terminals (set screws with springs)
55, 505: Housing screw screw (female screw)
56: Ball bearing 6, 60, 600: Housing lid (stator)
61, 62, 63, 64, 601, 602, 603, 604: projection of housing cover (key)
65: Screw screw for housing lid 66, 67, 68, 69: Set screw for housing lid 71, 72, 73, 74, 701, 702, 703, 704: Lead wire 8, 80, 800: Ultrasonic linear actuator

Claims (4)

  When a short cylindrical 3D electrostrictive revolution element having a cylindrical axial length (or height) shorter than the outer diameter length is excited at a second resonant frequency along the axial length, which is higher than the fundamental resonant frequency along the circumference, In an actuator that uses a powerful rotational torque generated on both end faces as a power source, a rotor configured to be pressed against at least one end face of both ends of the electrostrictive revolution rotator cylinder and receive the generated torque and fixed It consists of a child and a cylindrical or columnar moving member having a screw screw on at least a part of its outer peripheral surface. As a first means, the moving member rotates together with the rotor, but lightly slides in the axial direction. As described above, by engaging the rotor and further engaging the screw screw portion of the moving element with the matching stator female screw, the moving element rotates linearly or the second means. As the mover's The rotor is rotated by engaging the threaded portion with the female screw of the rotor with a matching screw screw and engaging the stator so that the slider slides but does not rotate. According to the first means, such as means for performing no linear movement, the moving element performs linear movement while rotating, and according to the second means, the moving element performs linear movement without rotation. Ultrasonic linear actuator   In the actuator using the rotational torque generated on both end faces of the short cylindrical 3D electrostrictive revolving element described in item 1 as a power source, the rotor mechanism is a thin-walled or fixed ring at one end. The other end of the cylinder or column passes through the revolving rotator, and the revolving rotator is sandwiched between a circular ring fixed or fitted to the tip of the circular rotator, and compression is performed between at least one of the circular rings at both ends and the revolving rotator. By inserting a spring and applying a pressure that presses both rings against the revolving rotator, and placing the fulcrum on the rotor itself, at the same time, using both the powerful rotational torques generated at both ends, The rotor is supported by the torque itself, and friction loss associated with supporting by a fixed object such as a bearing is eliminated. As a first means, the rotor rotates together with the rotor, but the axial direction In order to slide lightly, By engaging the screw screw part of the moving element with the corresponding stator female screw, the moving element rotates linearly or as a second means, By engaging the threaded portion with the internal thread of the rotor with a matching screw screw, and further engaging the stator so that the slider slides but does not rotate, the slider is rotated. According to the first means, such as a means for performing no linear motion, the ultrasonic wave is configured such that the movable element performs linear motion while rotating, and according to the second means, the movable element performs linear motion without rotation. Linear actuator.   A ring is pressed against each of both end faces of the electrostrictive revolution element described in Item 2 and the fulcrum of the applied pressure is placed on the rotor itself, and at the same time, the powerful rotational torque generated on both end faces is utilized. Thus, the rotor is supported by the torque itself, and the rotor has a structure that eliminates friction loss associated with support by a fixed object such as a bearing, and the rotor has a coil spring or an equivalent extension spring function. The rotor comprises a rotor and a stator, and a cylindrical or columnar moving element having a screw screw applied to at least a part of the outer peripheral surface thereof. Rotate with the rotor, but engage with the rotor so that it slides lightly in the axial direction, and then move by moving the screw screw part of the mover to the matching stator female screw. Child times As a means for linear movement or as a second means, the threaded portion of the slider is engaged with the internal thread of the rotor to which the screw screw is matched, and the slider is further slid but the rotation is not performed. According to the first means, such as a means for the moving element to perform a linear motion without rotation by engaging with the stator, the moving element moves linearly while rotating, and the second means For example, an ultrasonic linear actuator constructed so that the mover performs linear motion without rotation.   When a short cylindrical 3D electrostrictive revolution element having a cylindrical axial length (or height) shorter than the outer diameter length is excited at a second resonant frequency along the axial length, which is higher than the fundamental resonant frequency along the circumference, In an actuator that uses strong rotational torque generated on both end faces as a power source, either an internal screw surface of the electrostrictive rotator cylinder is directly screwed, or a ring or thin cylinder with an internal screw thread is electrostricted. By engaging the male screw of the mover, which is fixed and integrated with the end face or inner peripheral surface of the revolving rotator, and has a screw male screw aligned with the female screw on the outer peripheral surface, with the screw female screw, linear torque or An ultrasonic linear actuator characterized in that a rotating linear torque is applied and a rotor is omitted.

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