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 SIGMA 4.5mm f2.8 EX DC HSM Circular Fisheye for Canon US $587.25 
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 Sigma AF 10-20mm f/4-5.6 EX DC HSM -77mm- f/Canon US $479.00
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 Sigma 18-200mm f3.5-6.3 DC OS Digital Lens f/Canon US $399.00
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 Sigma 18-250mm F3.5-6.3 DC OS HSM Zoom Lenses f/Canon US $479.00
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 SIGMA 18-50mm 2.8 -4.5 DC OS F Canon XS XSI XT XTI TI US $239.99
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 Sigma 17-50mm f2.8 EX DC OS HSM - Canon Fit US $932.36
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 Sigma 10-20mm F3.5 EX DC HSM Lens - Canon fit US $790.13
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 Sigma EX 10 mm - 20 mm F/4.0-5.6 AF HSM DC Lens For Canon w/ box US $399.00
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 Sigma 18-200mm f/3.5-6.3 DC OS HSM Lens for Canon US $479.00
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 Sigma AF 18-50mm 1:3.5-5.6 DC Camera Lens for Canon US $149.99
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 Sigma EX 10 mm - 20 mm F/3.5 HSM DC Lens For Canon-Brand New in Box! US $649.00
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 Sigma 18 mm - 250 mm F/3.5-6.3 HSM Aspherical OS AF IF DC Lens Canon with Filter US $301.00
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 SIGMA 18-50mm F2.8 -4.5 DC OS F Canon 450D 500D 350D US $239.00
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 SIGMA 18-50mm F2.8 -4.5 DC OS F Canon XS XSI XT XTI TI US $259.00
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 Sigma EX 30 mm f/1.4 HSM DC Lens For Canon good condition for photo or video US $263.11
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 Sigma 17-50mm F2.8 EX DC OS HSM Wide Angle Lens f/Canon US $669.00
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 Sigma 10-20mm 4-5.6 EX DC HSM AF Lens f/ Canon+ KIT NEW US $499.97
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 Sigma 10-20mm f/3.5 EX DC HSM AF Lens f/ Canon+ KIT NEW US $655.97
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 Sigma 10-20mm f/3.5 EX DC HSM AF Zoom Lens f/ Canon NEW US $649.00
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 Sigma 10mm 2.8 EX DC HSM Fisheye Lens f/Canon+ KIT NEW US $649.00
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 Sigma 17-50mm F2.8 EX DC OS HSM Lens for Canon +Kit NEW US $669.00
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 Sigma 17-50mm F2.8 EX DC OS HSM Zoom Lens for Canon NEW US $669.00
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 Sigma 17-70mm f/2.8-4 DC Macro OS HSM Lens f/Canon NEW US $544.00
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 Sigma 17-70mm f/2.8-4 DC OS HSM Lens f/Canon + Kit NEW US $559.97
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 Sigma 18-200mm f/3.5-6.3 II DC OS HSM Telephoto Lens for Canon + Kit NEW US $427.97
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 Sigma 18-200mm f/3.5-6.3 II DC OS HSM Telephoto Lens for Canon NEW US $399.00
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 Sigma 4.5mm f/2.8 EX DC HSM Fisheye Lens for Canon NEW US $899.00
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 Sigma 4.5mm f/2.8 EX DC HSM Fisheye Lens- Canon+KIT NEW US $899.00
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 Sigma 8-16 mm f/4.5-5.6 DC HSM Lens for Canon + KIT NEW US $699.00
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 Sigma 8-16mm f/4.5-5.6 DC HSM Lens for Canon 203101 NEW US $699.00
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 Sigma AF 30mm f/1.4 EX DC HSM Lens for Canon + KIT NEW US $489.00
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 Sigma AF DC 10 mm f/2.8 EX HSM Fisheye Lens f/Canon NEW US $649.00
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 Sigma AF DC 10 mm-20 mm f/4-5.6 EX Lens for Canon NEW US $479.00
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 Sigma AF DC 30mm f/1.4 EX Wide Angle Lens for Canon NEW US $489.00
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 Brand New Sigma 10-20mm f/3.5 EX DC HSM for Canon (UPC: 0085126202545) US $649.40
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 Sigma 10-20mm F/4-5.6 EX DC HSM Zoom Lens for Canon US $365.00
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 Sigma 8-16mm F4.5-5.6 DC HSM for CANON US $600.00
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 Sigma EX 10 mm - 20 mm F/4.0-5.6 AF HSM DC Lens For Canon US $360.00
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 SIGMA 17-70mm OS DC Lens 17-70 for CANON T2i T3 40d 50d 60d 7d - 3 YEAR WARRANTY US $469.00
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 SIGMA 17-70mm OS DC Lens for CANON EOS and REBEL Cameras -3 YEAR USA WARRANTY US $469.00
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 Sigma 18 mm - 50 mm F/2.8-4.5 OS HSM DC Lens For Canon US $108.51
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 Sigma DC 55-200mm 35-80mm 70-210mm 28-70mm Canon Eos Rebel S Pentax A3000 Bundle US $89.00
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 Sigma 30mm f/1.4 EX DC AF HSM Lens for Canon EOS SLR US $489.00
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 Sigma 8-16mm f/4.5-5.6 DC HSM Lens for Canon EOS 8-16 US $699.00
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 Sigma 4.5mm f/2.8 EX DC HSM Fisheye Lens for Canon EOS US $899.00
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 Sigma 18-250mm f/3.5-6.3 DC OS for Canon EOS 880-101 US $479.00
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 Sigma 18-125mm f/3.8-5.6 DC OS HSM Lens for Canon EOS US $339.00
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 Sigma 10mm f/2.8 EX DC HSM Fisheye Lens for Canon EOS US $649.00
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 Sigma 10-20mm f/4-5.6 EX DC HSM Lens for Canon EOS SLR US $479.00
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 Sigma 10-20mm f/3.5 EX DC HSM Lens for Canon EOS 10-20 US $649.00
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 Sigma EX 10 mm-20 mm F/4.0-5.6 HSM DC AF Lens For Canon.Hood,caps and case. US $380.00
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 Sigma 17 mm - 70 mm F/2.8-4 DC OS HSM Lens For Canon Filter protected since day1 US $550.00
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 Sigma 8-16mm F4.5-5.6 DC wide angle lens for Canon US $300.00
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 SIGMA 17-70mm OS DC Lens for CANON XS XSi XTi T3i T2i - 3 YEAR USA WARRANTY US $469.00
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 SIGMA 17-50mm f/2.8 EX DC OS Lens for CANON + 4 YEAR WARRANTY T2i T3i 60d US $669.00
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 SIGMA 30mm f/1.4 EX DC HSM Wide-Angle Lens for Canon EOS - 300101 US $489.00
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 Sigma 50-200mm F4-5.6 DC OS HSM Zoom Lens f/Canon US $159.00
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 Sigma 10mm F2.8 EX DC Fisheye HSM Lens f/Canon US $649.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Lens Kit for Canon 60D 50D 40D Cameras US $478.90
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 SIGMA 18-250mm f/ 3.5-6.3 DC OS HSM Lens Kit for Canon EOS Rebel 550D 600D 1100D US $519.00
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 SIGMA 17-70mm f/ 2.8-4.0 DC MACRO OS HSM Lens Kit for Canon EOS Rebel Cameras US $509.00
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 SIGMA 10-20mm 10-20 f/3.5 EX DC Camera Lens for Canon EOS XT XTi XS XSi Cameras US $649.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Lens for Canon EOS Rebel 7D XS XSi T3 US $467.95
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 SIGMA 18-250mm f/ 3.5-6.3 DC OS HSM Camera Lens Kit for Canon EOS Rebel Cameras US $519.00
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 Brand New Sigma 10-20mm f/4-5.6 EX DC HSM for Canon (UPC: 0085126201272) US $525.33
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 Sigma 18-200mm f/3.5-6.3 DC OS for Canon EOS SLR US $389.00
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![Sigma 18-250mm F3.5-6.3 DC OS HSM Zoom Lenses [For Canon]](http://www.chelsyshore.com/images/plus/extra12Z915692430_0143.jpg) Sigma 18-250mm F3.5-6.3 DC OS HSM Zoom Lenses [For Canon] US $469.99
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 Sigma 18 mm - 200 mm F/3.5-6.3 HSM SLD OS Aspherical DC Lens For Canon EOS US $250.00
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 Sigma 10mm f/2.8 EX DC HSM Fisheye Lens 3 Piece Kit For Canon Cameras 10 mm USA US $649.00
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 Sigma EX 30 mm F/1.4 HSM DC Lens For Canon US $325.00
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 Sigma 50mm - 150mm F2.8 APO EX DC Lens for Canon -- Complete in Original Packagi US $102.50
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 SIGMA 10-20mm f/4-5.6 EX DC HSM AF Camera Lens for Canon EOS Rebal T3 T3i T2i US $479.00
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 SIGMA 17-70mm f/2.8-4 DC OS HSM Camera Lens for Canon EOS Rebel 550D 600D - NEW US $469.00
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 SIGMA 17-70mm f/ 2.8-4.0 DC MACRO OS HSM Lens Kit for Canon EOS 60D 50D 7D - NEW US $509.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Lens Kit for Canon 1Ds Mark I II 60D NEW US $509.00
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 SIGMA 17-70mm f/ 2.8-4.0 DC MACRO OS HSM Lens for Canon EOS Rebel T3 T3i T2i T1i US $509.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Lens for Canon 1Ds Mark I II 60D 7D NEW US $469.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Lens for Canon EOS Rebel Cameras - NEW US $469.00
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 SIGMA 10-20mm F 3.5 EX DC Camera Lens for Canon EOS Rebel 50D 40D 30D 7D Cameras US $649.00
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 SIGMA 18-250mm f/3.5-6.3 DC OS HSM Lens for Canon EOS Rebel DSLR Cameras - NEW US $479.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Camera Lens for Canon EOS Rebel T3i T2i US $469.00
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 SIGMA 18-200MM F3.5-6.3 DC CANON MOUNT ZOOM BRUSH NEW AUTHENTIC REPAIR PART OEM US $12.00
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 SIGMA 18-200MM F3.5-6.3 DC CANON MOUNT SCREW 0524055 NEW AUTHENTIC PART OEM US $5.00
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 SIGMA 18-200MM F3.5-6.3 DC CANON MOUNT SCREW PART # 0272050 NEW REPAIR PART OEM US $5.00
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 SIGMA 18-200MM F3.5-6.3 DC LENS CANON MOUNT SCREW PART # 0227040 NEW PART OEM US $5.00
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 SIGMA 18-200MM F3.5-6.3 DC SWITCH FLEX FPC CABLE BOARD CANON MOUNT NEW PART OEM US $18.00
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 SIGMA 18-50mm F2.8 -4.5 DC OS F Canon 50D 40D 30D 20D US $239.99
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 SIGMA 18-50mm F2.8 -4.5 DC OS IS F Canon T2I T1I XSI XS US $239.00
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 Sigma 18-200mm f/3.5-6.3 OS Aspherical AF DC Lens For Canon US $299.00
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 Brand New Sigma 8-16mm f/4.5-5.6 DC HSM for Canon (UPC: 085126203542) US $733.78
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 Sigma 10mm - 20mm f/4-5.6 EX DC HSM Lens for Canon DSLRs #201101 US $479.00
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 Sigma 17mm-70mm f2.8-4 DC OS HSM Macro Lens f/Canon EOS #668101 US $469.00
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 Sigma 18 mm - 200 mm F/3.5-6.3 Aspherical IF DC Lens For Canon US $122.50
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 Sigma EX 17 mm - 50 mm F/2.8 EX OS DC Lens for CANON CANON CANON CANON US $400.00
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 SIGMA 10-20mm f/ 4-5.6 EX DC HSM Camera Lens Accessory Kit for Canon 60D 50D 40D US $524.00
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 SIGMA 17-70mm f/2.8-4.0 DC MACRO OS HSM Lens for Canon EOS Rebel T3i T2i T1i NEW US $469.00
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Sigma Dc Canon
SIGMA 18-250mm DC OS and CANON Rebel T1i
Ultrasonic Motor
Mechanism
Dry friction is often used in contact, and the ultrasonic vibration induced in the stator is used both to impart motion to the rotor and to modulate the frictional forces present at the interface. The friction modulation allows bulk motion of the rotor (i.e., for farther than one vibration cycle); without this modulation, ultrasonic motors would fail to operate.
Two different ways are generally available to control the friction along the stator-rotor contact interface, traveling-wave vibration and standing-wave vibration. Some of the earliest versions of practical motors in the 1970s, by Sashida, for example, used standing-wave vibration in combination with fins placed at an angle to the contact surface to form a motor, albeit one that rotated in a single direction. Later designs by Sashida and researchers at Matsushita, ALPS, and Canon made use of traveling-wave vibration to obtain bi-directional motion, and found that this arrangement offered better efficiency and less contact interface wear. An exceptionally high-torque 'hybrid transducer' ultrasonic motor uses circumferentially-poled and axially-poled piezoelectric elements together to combine axial and torsional vibration along the contact interface, representing a driving technique that lies somewhere between the standing and traveling-wave driving methods.
A key observation in the study of ultrasonic motors is that the peak vibration that may be induced in structures occurs at a relatively constant vibration velocity regardless of frequency. The vibration velocity is simply the time derivative of the vibration displacement in a structure, and is not (directly) related to the speed of the wave propagation within a structure. Many engineering materials suitable for vibration permit a peak vibration velocity of around 1 m/s. At low frequencies 50 Hz, say a vibration velocity of 1 m/s in a woofer would give displacements of about 10 mm, which is visible to the eye. As the frequency is increased, the displacement decreases, and the acceleration increases. As the vibration becomes inaudible at 20 kHz or so, the vibration displacements are in the tens of micrometers, and motors have been built that operate using 50 MHz surface acoustic wave (SAW) that have vibrations of only a few nanometers in magnitude. Such devices require care in construction to meet the necessary precision to make use of these motions within the stator.
More generally, there are two types of motors, contact and non-contact, the latter of which is rare and requires a working fluid to transmit the ultrasonic vibrations of the stator toward the rotor. Most versions use air, such as some of the earliest versions by Dr. Hu Junhui. Research in this area continues, particularly in near-field acoustic levitation for this sort of application. (This is different from far-field acoustic levitation, which suspends the object at half to several wavelengths away from the vibrating object.)
Applications
Canon was one of the pioneers of the ultrasonic motor, and made the "USM" famous in the late 1980s by incorporating it into its autofocus lenses for the Canon EF lens mount. Numerous patents on ultrasonic motors have been filed by Canon, its chief lensmaking rival Nikon, and other industrial concerns since the early 1980s. The ultrasonic motor is now used in many consumer and office electronics requiring precision rotations over long periods of time.
The technology has been applied to photographic lenses by a variety of companies under different names:
Canon USM, UltraSonic Motor
Minolta, Sony SSM, SuperSonic Motor
Nikon SWM, Silent Wave Motor
Olympus SWD, Supersonic Wave Drive
Panasonic XSM, Extra Silent Motor
Pentax SDM, Supersonic Drive Motor
Sigma HSM, Hyper Sonic Motor
References
^ Ueha, S.; Tomikawa, Y.; Kurosawa, M.; Nakamura, N. (December 1993), Ultrasonic Motors: Theory and Applications, Clarendon Press, ISBN 0-1985-9376-7
^ Shigematsu, T.; Kurosawa, M.K.; Asai, K. (April 2003), "Nanometer stepping drives of surface acoustic wave motor", IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 50, IEEE, pp. 376385
^ Hu, Junhui; Li, Guorong; Lai Wah Chan, Helen; Loong Choy, Chung (May 2003), "A standing wave-type noncontact linear ultrasonic motor", IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 48, issue 3, IEEE, pp. 699708
^ Hu, Junhui; Nakamura, Kentaro; Ueha, Sadauki (May 1997), "An analysis of a noncontact ultrasonic motor with an ultrasonically levitated rotor", Ultrasonics, 35, Elsevier, pp. 459467
^ Koyama, D.; Takeshi, Ide; Friend, J.R.; Nakamura, K.; Ueha, S. (September 2005), "An ultrasonically levitated non-contact sliding table with the traveling vibrations on fine-ceramic beams", 2005 IEEE Ultrasonics Symposium, 3, IEEE, pp. 15381541
External links
Ultrasonic Actuators, Motors and Sensors page, from NASA JPL
Micro/Nano Physics Research Laboratory, with research on ultrasonic piezoelectric actuators by Dr James Friend
Institute of Piezomechanics, Kaunas University of Technology, Lithuania
Disassembly of a Canon EF lens, revealing an ultrasonic motor
v d e
Electric motors
Broad Motor Categories
Synchronous motor AC motor DC motor
Conventional
Electric Motors
Induction Brushed DC Brushless DC Stepper Linear Unipolar Reluctance
Novel Electric Motors
Ball bearing Homopolar Piezoelectric Ultrasonic Electrostatic Switched Reluctance
Motor
Controllers
Adjustable-speed drive Amplidyne Direct torque control Direct on line starter Electronic speed control Metadyne Motor controller Variable-frequency drive Vector control Ward Leonard control Thyristor drive
See also
Barlow's Wheel Nanomotor Traction motor Lynch motor Mendocino motor Repulsion motor Inchworm motor Booster (electric power) Brush (electric) Electrical generator Alternator
Categories: Electric motorsHidden categories: Wikipedia articles needing clarification from October 2009 | All Wikipedia articles needing clarification
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