Piezomotor Uppsala Ab

Nokia Corporation

Piezomotor Uppsala Aktiebolag

Anders Jansson

Stefan Johansson

Christer Mattsson

Mats Bexell

Jonas Eriksson

Olov Johansson

Karl H&aring;kansson

A digital camera is constructed with multiple lenses mounted in a pair of tubular elements which are nested together for relative axial movement. Movement is provided by piezoelectric actuators mounted externally to a support tube on flexible printed circuit board elements. Each lens tube is provided with a drive rail which extends at least partially over the length of the lens tube and projects radially outward from the periphery of each of the tubes. The rails are accessible to the engagement pads of the piezoelectric actuators to allow the transmission of drive forces to each of the tubes.

Digital camera system with piezoelectric actuators

The present invention combines bending mode mechanical (f) and electrical (f) resonances, whereby a relatively good efficiency can be achieved within a relatively broad frequency range (&#x394;f). An electrical resonance (f) or mechanical resonance is designed to be situated in the same order of magnitude as another mechanical resonance (f), but separated therefrom. Preferably, the separation (&#x394;f) is smaller than 2f/Q, where fis the resonance frequency for the resonance having lowest quality value, and Qis the corresponding quality value of the mechanical resonance. An electromechanical motor comprising a driving element and electrical resonance circuit according to the above ideas may comprise a double bimorph driving element having one single actuating point influencing a body to be moved. The double bimorph driving element is excited in bending vibrations perpendicular to a main displacement direction, whereby both tangential and perpendicular motions are created by bending mode vibrations.

Near-resonance wide-range operating electromechanical motor

An electromechanical actuatoris disclosed, having drive elements () movable in two dimensions and connected to an actuator backing (). The actuator backing () is made of a material being ferromechanically inactive. Furthermore, the joint between the drive element () and the actuator backing () is stiff and highly stable. This is achieved by use of an irreversible joint made e.g. by thermoset plastic glues, diffusion bonding or co-sintering. Co-sintering is to prefer. The actuator backing () material is selected to be stiff, preferably having a stiffness above 70 GPa and more preferably above 100 GPa, and having a high heat conductivity, preferably above 5 W/mK and more preferably above 10 W/mK, Electrodes () are preferably integrated in the actuator backing to increase stiffness as well as improving the heat conductivity. The drive elements () are preferably covered (), at least at the driving surface, by heat-conducting material.

Wide frequency range electromechanical actuator

According to the present invention, electromechanical motors are driven in such a way that contact portions of driving elements ( ) are moved along smooth trajectories. The velocity is varied, the average velocity being lower during the time when the element ( ) is in contact with a moving object ( ) than during the contact free time. Preferably, the main displacement velocity component is non-negligible when switching between sets of elements ( ). When stopping the motor, the actuating sets of elements ( ) are brought into a voltage-free condition, one set at a time. The contact portions of the elements ( ) are lapped with such an accuracy, that the normal force applied between the moving object and the stator ( ) is large enough to cause elastic deformations of the stator ( ) that are in the same order of magnitude or larger than the accuracy of the lapping.

Fine control of electromechanical motors

An electromechanical motor according to the present invention has a stator with a drive element consisting of two serially connected bending sections and a central drive pad, for actuating on a body to be moved. The drive element extends parallel to the body. The drive pad and/or the body is elastic. Preferably, the drive pad has a lower stiffness than the body. The elasticity of the drive pad allows an assimilation of a part of the travelling wave energy applied to the drive element. The backbone of the stator is arranged to restrict the drive element from being removed from the body, but at the same time allow the drive element to be translated towards the body and even leave the mechanical contact with the backbone for shorter periods of time. Support means are preferably designed with convex surfaces in order to allow self-centering of the different parts of the motor.

Near-resonance electromechanical motor

In a method according to the present invention, charging and discharging of motor phases ( A, B) in an electromechanical motor is performed with a small voltage difference between the voltage source and the capacitive load of the motor phase ( A, B). This is accomplished by connecting a series of voltage sources ( ), one at a time. Energy from the discharging operation is stored to be used in subsequent charging operations. In a device according to the present invention, the voltage sources ( ) are preferably provided by means of capacitive or induction voltage step-up or step-down circuits. Preferably, switches ( ) control the charging and discharging. In a preferred embodiment, the capacitance of one motor phase ( A) is used for storing charge resulting from the discharge from another motor phase ( B).

Growing community of inventors

Uppsala, Sweden

Anders Jansson