Abstract:
A rotary motor and a method of making the same include a vibrating motor body which has two orthogonal first bending modes and is substantially enclosed within a housing. A shaft is frictionally coupled to the vibrating motor body and is arranged to rotate in at least one direction about a rotation axis in response to the vibrating motor body. The shaft is frictionally coupled the vibrating motor body by a force substantially perpendicular to the rotation axis. One or more bearings support the shaft, are connected to the housing, and define the axis of rotation of the shaft.

Description:
This application claims the benefit of U.S. Provisional Application No. 61/693,665, filed Aug. 27, 2012 which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The present invention generally relates to rotary motors, and more particularly, to piezoelectric ultrasonic rotary motor systems which may include an attached unbalanced mass that generates an oscillating centripetal force perpendicular to an axis of rotation for use as a haptic actuator and methods thereof. 
     BACKGROUND 
     Haptic actuators are devices that generate vibrations that can be felt by a person. Haptic actuators have become increasingly important in applications in handheld devices, such as cellphones and smartphones. Additional background information about haptic actuators is disclosed in U.S. Patent Application Publication No. 2011/0241851 to Henderson et al., which is herein incorporated by reference in its entirety. 
     However, there are some limitations to the maximum reaction force that prior art haptic actuators can produce in practical applications. In particular, the dynamic force (for a small size motor and/or moderate driven power) may not be sufficient to accelerate the entire mobile phone handset and create vibrations that are perceived by the user. 
     When a motor of small size (e.g., 6 mm in length and up to 2 mm in diameter) is subject to a force of about 20 grams of force (20 gf) at the node points (points on the motor that have the lowest vibration amplitude for a first bending mode vibration), the vibration amplitude of the motor begins to be dampened, and the maximum rotation speed of the shaft begins to decrease. Since the centripetal force is about 0.63 N (over 60 gf) for 200 Hz rotation of a typical rotating (Tungsten) mass of 0.4 grams offset about 1 mm from the centreline of the shaft rotation, and it acts upon antinode points of the motor (both ends or center which have the highest vibration amplitudes for a first bending mode vibration), this centripetal force will dampen the motor vibration even more than the 20 gf preload force at the node points of the motor. Thus, the maximum rotation speed of the shaft is limited (much below 200 Hz) and the resulting centripetal force is not sufficient for many applications. 
     Another potential limitation for the maximum reaction force is due to the way the motor is mounted. In the prior art, the motor is typically compliantly secured to a housing at the node points by an elastomer material, such as silicone. Unfortunately, the compliance of this mounting method will degrade the transmission of the centripetal force from the rotating unbalanced mass through the motor and then to the housing. 
     SUMMARY 
     A rotary motor includes a vibrating motor body which has two orthogonal first bending modes and is substantially enclosed within a housing. A shaft is frictionally coupled to the vibrating motor body and is arranged to rotate in at least one direction about a rotation axis in response to the vibrating motor body. The shaft is frictionally coupled the vibrating motor body by a force substantially perpendicular to the rotation axis. One or more bearings support the shaft, are connected to the housing, and define the axis of rotation of the shaft. 
     A method of making a rotary motor includes providing a vibrating motor body which has two orthogonal first bending modes and is substantially enclosed within a housing. A shaft is frictionally coupled to the vibrating motor body by applying a force substantially perpendicular to the rotation axis. The shaft is arranged to rotate in at least one direction about a rotation axis in response to the vibrating motor body. One or more bearings are provided that support the shaft, are connected to the housing, and define the axis of rotation of the shaft. 
     This exemplary technology provides a number of advantages including providing more effective and efficient piezoelectric ultrasonic rotary motor apparatuses and methods. For example, this technology achieves a significant decrease in the dampening of the motor body and thus high vibration amplitude of the motor body and a high rotation speed of the shaft. Additionally, this technology reduces drag and system volume/length, as well as reducing stress inside the shaft during drop testing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an isometric view of an example of a rotary motor; 
         FIG. 1B  is a side view of the exemplary rotary motor shown in  FIG. 1A ; 
         FIG. 1C  is a partial top view and partial block diagram of exemplary rotary motor shown in  FIG. 1A ; 
         FIG. 1D  is end view of the exemplary rotary motor shown in  FIG. 1A ; 
         FIGS. 1E-1G  are a side sectional view, a top sectional view, and an end sectional view of the exemplary rotary motor shown in  FIG. 1A ; 
         FIGS. 2A and 2B  are the end view and isometric view of a tubular motor body and a wrapped around flexible printed circuit board of the exemplary rotary motor illustrated in  FIGS. 1A-1G ; 
         FIG. 2C  is an exploded view of a tubular motor body and a wrapped around flexible printed circuit board of the exemplary rotary motor as illustrated in  FIGS. 1A-1G ; 
         FIG. 2D  is an end view of a tubular motor body of the exemplary rotary motor as illustrated in  FIGS. 1A-1G ; 
         FIG. 2E  is an isometric view of a tubular motor body of the exemplary rotary motor as illustrated in  FIGS. 1A-1G ; 
         FIGS. 3A and 3B  are the side view and isometric view of an example preload spring in the loaded state used for the rotary motor illustrated in  FIGS. 1A-1G . 
         FIGS. 3C and 3D  are the side view and isometric view of an example preload spring in the relaxed state used for the rotary motor shown in  FIGS. 1A-1G ; 
         FIG. 4A  is side sectional view and isometric view of another example of a rotary motor; 
         FIG. 4B  is a partial isometric view and partial block diagram of the exemplary rotary motor as shown in  FIG. 4A ; 
         FIG. 5A  is a side sectional view of yet another example of a rotary motor; 
         FIG. 5B  is a partial isometric view and partial block diagram of the exemplary rotary motor as illustrated in  FIG. 5A ; 
         FIG. 6A  is a partial isometric view and partial block diagram of still another example of a rotary motor; and 
         FIGS. 6B-6D  are a side view, top view, and end view, respectively, of the exemplary rotary motor as illustrated in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary rotary motor system  100  is illustrated in  FIGS. 1A-2E . The exemplary rotor motor system  100  includes a tubular cage or housing  102 , a mount  104 , a flexible printed circuit board  108 , an integrated driver IC  110 , a DC voltage source  112 , an interface  114 , a tubular vibrating motor body  116  including a main body  116   a  and piezoelectric plates  144   a  and  144   b , a spring  120 , rotating shaft  124 , symmetrical unbalanced masses  132   a  and  132   b , bearings  136   a  and  136   b , washers  140   a ,  140   b ,  142   a  and  142   b , and optional rotational sensor  146 , although the motor system  100  could include other types and numbers of systems, devices, components and other elements in other configurations. The rotation axis of the rotary motor system  100  or the motor axis Z is indicated in  FIG. 1B . This exemplary technology provides a number of advantages including providing more effective and efficient piezoelectric ultrasonic rotary motor apparatuses and methods. 
     Referring to  FIGS. 1A-1G , the tubular cage or housing  102  is secured to the mount  104  by welding, although other types and numbers of mounts can be used. In this example, the mount  104  also has mounting holes  106   a  and  106   b , as illustrated in  FIGS. 1A, 1C, and 1F , which may be used to secure the rotary motor system  100  to a device, such as a mobile phone (not shown), although mount  104  may include other types and numbers of mount supporting elements. 
     Referring again to  FIGS. 1A-1E , the flexible printed circuit board  108  receives and transmits signals to the tubular motor body  116  to ultrasonically vibrate the tubular motor body  116 . A variety of suitable printed circuit boards are disclosed by way of example in U.S. Pat. No. 7,309,943 which is incorporated by reference in its entirety, although the flexible printed circuit board could include other types and numbers of elements configured to execute other types and numbers of functions. In this example, as illustrated in  FIG. 1C , the flexible printed circuit board  108  is coupled to the integrated driver IC  110 , which generates the driving signals to drive the tubular motor body  116 , such as the integrated driver IC described in U.S. Patent Application Publication No. 2011/0241851, which is herein incorporated by reference in its entirety. The integrated driver IC  110  is coupled to a power source  112 , such as a DC voltage source, and an interface device  114 , although other types and numbers of systems, devices, components and elements may be coupled together in other configurations. The interface device  114  may be used to operatively establish a connection and communicate between the rotary motor system  100  and a device, such as a mobile phone (not shown). In one example, the interface device  114  is an I 2 C serial control interface, although other types and numbers of interface devices may be contemplated to provide a wired connection between the rotary motor system  100  and a device. 
     Referring again to  FIGS. 1A-1G , the tubular motor body  116  is located inside the tubular cage or housing  102 , although other types and numbers of motor bodies, such as by way of example only the one disclosed in U.S. Patent Application Publication No. 2011/0241851, which is herein incorporated by reference in its entirety, which are in other locations could be used. 
     Referring now to  FIGS. 2A-2E , an exemplary tubular motor body  116  is illustrated. The tubular motor body  116  includes a main body  116   a  and piezoelectric plates  144   a  and  144   b . The main body  116   a  is constructed of a solid material, such as metals, polymers or ceramics by way of example only, such that the tubular motor body  116  may vibrate with low loss and high mechanical quality factor (Qm) at ultrasonic frequencies up to several hundred Kilohertz, although the main body  116   a  may be constructed of other types and numbers of suitable materials. In this example, the main body  116   a  provides two significantly orthogonal first bending vibration modes which have substantially equal resonant frequencies, although the main body  116   a  could provide other types and numbers of bending modes. 
     The main body  116   a  is bonded to a pair of piezoelectric plates  144   a  and  144   b , although the main body  116   a  may be attached to other numbers and types of piezoelectric elements at different locations. In this example, the piezoelectric plates  144   a  and  144   b  are co-fired multilayer devices, although other piezoelectric plates, such as single layer piezoelectric plates may be used. The piezoelectric plates  144   a  and  144   b  are bonded to the main body  116   a  using high strength adhesive, although other suitable bonding techniques may be used. Further explanation of piezoelectric ceramic materials and how they are used to generate ultrasonic vibrations is contained in U.S. Pat. No. 8,217,553, which is herein incorporated by reference in its entirety. 
     Referring to  FIGS. 2A-2C , in this example, the flexible printed circuit board  108  is wrapped around the tubular motor body  116 , although other configurations may be used. As illustrated in  FIGS. 2A and 2C , the flexible printed circuit board includes electrodes  146   a ,  146   b ,  146   c , and  146   d  which are attached to the piezoelectric plates  144   a  and  144   b  to apply a voltage to the piezoelectric plates  144   a  and  144   b , although other types and numbers of voltage applying elements may be used. 
     Referring to  FIG. 2B , in this example, main body  116   a  of the tubular motor body  116  includes additional cuts  148   a  and  148   b  located at the ends of the main body  116   a  which are used to fine tune the resonant frequencies of the first order bending resonant modes so that they are substantially the same, although the main body  116   a  may have other numbers and types of resonant frequency tuning elements and/or configurations in other locations. 
     The main body  116   a  includes notches  118   a  and  118   b  which are located at node points of the main body  116   a , as illustrated in  FIGS. 2B and 2C  although other types and numbers of node locators could be used. In this example, the notches  118   a  and  118   b  are used to secure the preload spring  120  to the main body  116   a , although other manners for securing a preloaded force can be used. End sections  122   a  and  122   b  of the spring  120  are pressed into the notches  118   a  and  118   b  of the main body  116   a , respectively. The preload spring  120 , illustrated in  FIGS. 3A-3D , is pressed between the main body  116   a  and the top surface of the mount  104  to provide constant preload force between the main body  116   a  and the mount  104 . 
     Referring now to  FIGS. 3A and 3B , spring  120  is illustrated in a loaded state with a targeted preload force. Spring  120  in a relaxed or free state is shown in  FIGS. 3C and 3D . In this example, the spring  120  is made of high strength stainless steel, although other suitable materials, such as elastomers by way of example only, may be used. The spring  120  is engineered to have proper stiffness for easy manufacturing tolerance and to provide rotational stability for the rotary motor system  100 . The configurations of the spring  120  illustrated in  FIGS. 3A-3D  are exemplary and other suitable shapes and configurations may be contemplated. 
     Referring again to  FIGS. 1A-1G , the rotating shaft  124  is located inside and extends throughout the main body  116   a , although the rotating shaft may be in other locations with other lengths. As illustrated in  FIGS. 1E and 1F , the diameter of the shaft  124  is slightly smaller than the inner diameter of the main body  116   a , although other configurations may be used. In this example, the shaft  124  includes an optional necked down section  126  with a decreased diameter, such that the tubular motor body  116  may only drive the shaft  124  at drive sections  128   a  and  128   b , where the corresponding motor vibration amplitude is at a maximum, although other configurations such as, by way of example only, bushing pads may be bonded to the inside of the tube  102  or outside the shaft  124  at drive sections  128   a  and  128   b . The shaft  124  also has end portions  130   a  and  130   b , which extend outside of the tubular motor body  116 , although the shaft  124  could have other positions. 
     In the exemplary embodiment shown in  FIGS. 1A-1G , end portions  130   a  and  130   b  of the shaft  124  are attached to symmetrical unbalanced masses  132   a  and  132   b , respectively, such that rotary motor system  100  is configured to act as a haptic actuator, although the exemplary rotary motor system  100  may or may not be attached to other objects and devices at different locations along the shaft  124  to provide other types and numbers of functions. 
     In this example, the unbalanced masses  132   a  and  132   b  are attached to the shaft  124  through a crimp/press fit, although the masses can be attached in other manners, such as with a high strength adhesive by way of example only. In this example, the unbalanced masses  132   a  and  132   b  include wrap-around or cantilevered portions  134   a  and  134   b , although the unbalanced masses may have other shapes and configurations. The cantilevered portions  134   a  and  134   b  reduce the actuator length along the motor axis and the actuator volume while the mr product is fixed. 
     Bearings  136   a  and  136   b  are pressed into the ends of tubular cage  102  and serve as a guide for the rotating shaft  124 , as shown in  FIGS. 1E and 1F , although other types and numbers of guides for the shaft  124  can be used. The bearings  136   a  and  136   b  may be simple journal bearings, which may be made of various materials, including oilite bearing material (oilite bronze), bronze, or plastics by way of example only, although the bearings  136   a  and  136   b  may be other types of bearings, such as ball bearings by way of example only. The bearings  136   a  and  136   b  provide long lasting low friction and small diametrical play (typically 5 to 15 micrometers) for the shaft  124 , although the bearings may provide other advantages. 
     The configuration of the mount  104 , the tubular cage  102  and the mounting holes  106   a  and  106   b  is designed to solidly connect bearings  136   a  and  136   b  to a target device (not shown), such as a mobile phone by way of example only. In this example, cantilevered portions  134   a  and  134   b  of the unbalanced masses  132   a  and  132   b , respectively, bring the center of gravity for each mass  138   a  and  138   b  inside the bearings  136  and significantly lower the stress inside the shaft  124  during drop testing. It is to be understood that the cantilevered portions  134   a  and  134   b  are optional and that different designs with different functions may be utilized. 
     Washers  140   a  and  140   b  are secured in between the tubular motor body  116  and the bearings  136   a  and  136   b , respectively and washers  142   a  and  142   b  are secured in between the unbalanced masses  132   a  and  132   b  and the bearings  136   a  and  136   b , respectively, although other friction reducing elements may be used. In this example, washers  140   a  and  140   b  and  142   a  and  142   b  are made of relatively soft and low friction material, such as plastics, although the washers may be made of any other suitable material. 
     In one example, the rotary motor system  100  includes an optional rotational speed sensor  150 , as illustrated in  FIG. 1C , to monitor the rotational speed of the unbalanced masses  132   a  and  132   b . The rotational speed sensor  150  detects rotational speed using various physical principles such as capacitive, optical, or magnetic principles, although other methods of measuring the rotational speed may be utilized. In one example, the monitored speed is fed back to the integrated drive  110  so that the rotational speed can be controlled in a controlled loop fashion, although the monitored speed could be provided to other control intefaces. 
     An exemplary operation of the rotary motor system  100  of the present invention will now be described with reference to  FIGS. 1A-2E . The operation of the tubular vibrating motor body  116  of the rotary motor system  100  is the same as described in U.S. Patent Application Publication No. 2011/0241851, which is incorporated herein by reference in its entirety, except as illustrated and described herein. Power source  112  and interface device  114  are connected to the integrated driver IC  110  to create a drive signal. Integrated driver IC  110  generates signals to ultrasonically vibrate the tubular motor body  116 . The drive signals are transmitted through the circuit board  108  to the tubular motor body  116 . In particular, the voltage signals are applied to the electrodes  146   a - 146   d  of piezoelectric plates  144   a  and  144   b.    
     When voltage signals are applied between the electrodes  146   a  and  146   b  of piezoelectric plate  144   a  and electrodes  146   c  and  146   d  of piezoelectric plate  144   b , the length of piezoelectric plates  144   a  and  144   b  changes. The changes in length of the piezoelectric plates  144   a  and  144   b  bends the main body  116   a . When the two ultrasonic signals are driven at the first order bending resonant frequency of the tubular motor body  116  and their phase difference is approximately 90 degrees, the tubular motor body  116  will be excited into a “hula-hoop” vibration in this example, which will further cause the shaft  124  to rotate in at least one direction. The tubular motor body  116  drives the shaft  124  at drive sections  128   a  and  128   b  where the corresponding vibration amplitude of tubular motor body  116  is at a maximum (antinode points). 
     The rotational output of the rotary motor system  100  is through the shaft  124 . The rotary motor system  100  may be coupled to a device at any point, or a combination of points, along the shaft  124 , such as one or both ends of the shaft  124 , or somewhere in the middle of the shaft  124 . The rotational output of the shaft  124  may be used for various purposes. By way of example only, the rotational output of the shaft  124  may be used to rotate a mirror, a prism, a medical device, a lead screw, or unbalanced masses, such as  132   a  and  132   b , although the rotational output may be used for other types and numbers of purposes. 
     In the embodiment shown in  FIGS. 1A-1G , when the shaft  124  and the unbalanced masses  132   a  and  132   b  are driven to the maximum rotation speed, the centripetal force generated by the unbalanced masses  132   a  and  132   b  is transmitted through bearings  136   a  and  136   b  to the tubular cage or housing  102 , the mount  104 , and finally to the targeted device, which generates a haptic feeling in the targeted device. Transmission through the bearings significantly causes less dampening of the tubular motor body  116  and thus high vibration amplitude of the tubular motor body  116  and a high rotation speed for the shaft  124 . The washers  140   a - 140   b  serve to reduce friction and reduce dampening of the tubular motor body  116  from the bearings  136   a - 136   b.    
     During operation, the node points on the tubular motor body  116  have the least amount of motion during vibration. Preloading the spring  120  at notches  118   a  and  118   b , which are located at the node points of the tubular motor body  116  decreases the amount of interference/damping to the vibration of the rotary motor system  100 . The notches  118   a  and  118   b  also prevent the preload spring  120  from moving away from or slipping from the node points during operation of the rotary motor system  100 . 
     Spring  120  is preloaded with a force of approximately 15 to 20 gf, which is approximately equally distributed to drive sections  128   a  and  128   b . The reaction forces at drive sections  128   a  and  128   b  can generate enough starting (frictional) drive force or torque to overcome the eccentric gravity of the unbalanced masses  132   a  and  132   b  and also accelerate it fast enough to meet the spin up time requirement (the rotary motor system  100  is required to reach a certain rotational speed at a specified amount of time). 
     Referring to  FIGS. 4A and 4B , another example of a rotary motor system  400  is shown. Rotary motor system  400  is the same in structure and operation as rotary motor system  100 , except as illustrated and described herein. Elements in rotary motor system  400  which are like those in rotary motor system  100  have like reference numerals. 
     Rotary motor system  400  has a single unbalanced mass  432  attached to the shaft  424 , although other elements in other numbers and configurations may be attached to shaft  424 . In this example, unbalanced mass  432  is attached to the shaft  424  through a crimp/press fit, although the mass can be attached in other manners, such as with a high strength adhesive by way of example only. In this example, the single unbalanced mass  432  is larger than the unbalanced masses shown attached to rotary motor system  100  shown in  FIGS. 1A-1G , although other sizes for the unbalanced mass may be used. 
     Rotary motor system  400  has a shaft stop or snap ring  450  clamped on the end of shaft  424  opposite the single unbalanced mass  432 , although other numbers and types of elements may be clamped on the shaft  424  at different locations along the shaft. 
     Bearings  436   a  and  436   b  serve as guides for the rotating shaft  424 , although other types and numbers of guides for the shaft  424  can be used. The bearings  436   a  and  436   b  may be simple journal bearings, which may be made of various materials, including oilite bearing material (oilite bronze), bronze, or plastics by way of example only, although the bearings  436   a  and  436   b  may be other types of bearings, such as ball bearings by way of example only. In this example, bearing  436   a  has an increased width to support the necessary drop test requirements, while bearing  436   b  is designed slightly narrower due to the decreased load, although bearings  436   a  and  436   b  may have other shapes and configurations. 
     In this example, the unbalanced mass  432  has a cantilevered design so that its center of gravity  438  is inside bearing  436   a , which significantly lowers the stress inside the shaft during drop test (especially in the direction perpendicular to the motor axis Z), although the unbalanced mass may be designed in other configurations. 
     As shown in  FIG. 4B , integrated driver IC  410  is connected to power source  412  and interface device  414  and integrated driver IC  410  generates the signals to ultrasonically vibrate the tubular motor body  416 . The drive signals are transmitted through the cable  408  to the motor body  416  and cause the shaft  424  and unbalanced mass  432  to rotate, although other electronic elements in different configurations may be used to generate the drive signals to operate the rotary motor  400 . 
     In this example, when the shaft  424  and the unbalanced mass  432  are driven to the maximum rotation speed, the centripetal force generated by the unbalanced mass  432  (attached to the rotating shaft  424 , which is supported by bearings  436   a  and  436   b ) is transmitted through bearings  436   a  and  436   b , the cage or housing  404 , the mount  402 , and finally to the targeted device (not shown), and hence a haptic feeling is generated. 
     Another embodiment of a rotary motor system  500  of the present invention is illustrated in  FIGS. 5A and 5B . Rotary motor system  500  is the same in structure and operation as rotary motor system  100 , except as illustrated and described herein. Elements in rotary motor system  500  which are like those in rotary motor system  100  have like reference numerals. 
     Rotary motor system  500  has a singled unbalanced mass  532  located between the two bearings  536   a  and  536   b , although other numbers of unbalanced masses may be used in other locations. In this example, bearing  536   a  is pressed into a frame  552  and bearing  536   b  is pressed into cage or housing  502 , which is joined with frame  552  by methods such as welding, although other methods of joining the cage  502  and frame  552  may be used. The center of gravity  538  of the unbalanced mass  532  is located outside the bearing  536   a  due to length limitations. In this example, bearing  536   a  is made wider to handle the increased load, although bearing  536   a  may have other shapes and configurations. Constrained by frame  552  and cage  502  in the motor axis Z, the bearings  536   a  and  536   b  cannot fall out in a drop test along the motor axis Z. 
     Rotary motor system  500  includes three thin washers  540   a - c , although other numbers and types of friction reducing elements may be used to increase performance. Washer  540   a  separates bearing  536   a  and the unbalanced mass  532  and reduces drag to the rotating mass/shaft during actuator operation. Washer  540   b  separates the unbalanced mass  532  and the motor tube  516  and reduces friction and the dampening to the tubular motor body  516  during actuator operation. Washer  540   c  separates the tubular motor body  516  and bearing  536   b  and it also minimizes the friction and dampening to the tubular motor body  516 . 
     As shown in  FIG. 5B , integrated driver IC  510  is connected to power source  512  and interface device  514  and it generates the signals to ultrasonically vibrate the motor body  516 . The drive signals are transmitted through the cable  508  to the motor body  516  and cause the shaft  524  and unbalanced mass  532  to rotate, although other electronic elements in different configurations may be used to generate the drive signals to operate the rotary motor system  500 . 
     In this example, when the shaft  524  and the unbalanced mass  532  are driven to the maximum rotation speed, the centripetal force generated by the unbalanced mass  532  (attached to the rotating shaft  524 , which is supported by bearings  536   a  and  536   b ) is transmitted through bearings  536   a  and  536   b , the cage  502 , the mount  504 , and finally to the targeted device (not shown), and hence a haptic feeling is generated. 
     Another embodiment of a rotary motor system  600  of the present invention is illustrated in  FIGS. 6A through 6D . Rotary motor system  600  is the same in structure and operation as rotary motor  100 , except as illustrated and described herein. Elements in rotary motor system  600  which are like those in rotary motor system  100  have like reference numerals. 
     Rotary motor system  600  includes two symmetric masses  632   a  and  632   b , which do not include cantilevered or wrapped-around portions, although other numbers of unbalanced masses with different configurations may be used. In this example, the masses  632   a  and  632   b  have smaller diameters (compared with that of masses  232   a  and  232   b  in haptic actuator  200 ) and thus can drastically reduce the height profile of the whole haptic actuator or device. 
     As shown in  FIG. 6A , integrated driver IC  610  is connected to power source  612  and interface device  614  and it generates the signals to ultrasonically vibrate the motor body  616 . The drive signals are transmitted through the cable  608  to the motor body  616  and cause the shaft  624  and unbalanced masses  632   a  and  632   b  to rotate, although other electronic elements in different configurations may be used to generate the drive signals to operate the rotary motor system  600 . 
     Accordingly, as illustrated and described with the examples herein provides more effective and efficient piezoelectric ultrasonic rotary motor apparatuses and methods. With this technology, high rotation speed, larger vibrational force, and longer life for the rotary motor system may be obtained. 
     Having thus described the basic concept of the invention, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the invention. Accordingly, the invention is limited only by the following claims and equivalents thereto.