High - resolution piezoelectric angular positioning device

The invention relates to the field of devices, in particular to high-resolution angular positioning and measuring systems, including optical element positioning devices.

A positioning device is known in which the rotary motion is formed by a piezoceramic plate with electrodes fixed in the housing and, by means of a friction-resistant element, in contact with a driving ring-shaped link mounted in the bearing supports. One piezo-ceramic plate electrode is divided into two symmetrical portions and the other is continuous. The electrodes are connected to a high-frequency power supply (see U.S. Patent No. 6,765,335 B2, H01L 41/08; July 20, 2004).

The specified device employs a bearing structure which does not guarantee the accuracy of the positioning of the driving link with respect to its axis of rotation and perpendicular to its axis of rotation.

A rotary actuator is known, consisting of a housing incorporating a piezo-ceramic ring with electrodes on which a ring-shaped element interacting with a rotor of similar shape is mounted on a flat surface. The rotor is connected to a shaft located in the bearing supports. Piezo-ceramic ring electrodes are connected to a high-frequency power supply (see U.S. Patent No. 4,562,374, H01L41 / 08; 1985-12-31).

In the above prototype, positioning is accomplished by the oscillatory wave oscillations of a rotating shaft, which are electrically excited by an elliptical trajectory of a piezoceramic ring having all points on a flat surface. Micro vibrations are transmitted to the ring member and the rotor and shaft. Technologically sophisticated overall drive design with bearing supports causes errors in rotor and shaft rotational axis and plane perpendicular to their axis of rotation, which prevents the required positioning accuracy.

The object of the invention is to increase the accuracy of positioning.

The object of the present invention is achieved by the fact that a high resolution piezoelectric angular positioning device consisting of a housing, a rotary motion piezo actuator embedded therein, consisting of a rectangular profile piezo-ceramic element with electrodes connected to a high frequency power source, is securely attached to the base 120 ° at an angle to the central axis of the positioner (in the Z direction). The piezo-ceramic element has a rigidly fixed, highly machined L-ring contact ring made of ferromagnetic material which centers the annular rotor on its axis of rotation with three radial supports, two of which are rigid and made of abrasion resistant material, and one, elasticated and made of a low-friction material (eg, a phoroplast), which creates an elastic clamp between the rotor and the contact ring. The inner side surface of the rotor is also rigidly mounted with three supports made of permanent magnets covered with a thin layer of low-friction material (such as a phoroplast), which rests on the flat surface of the contact ring and is accurately located relative to its axis of rotation. All six supports mounted to the rotor are positioned at an angle of 120 ° to its axis of rotation, which coincides with the center axis of the device. As a result, the abovementioned supports uniformly distribute both radial and axial loads and ensure the positioning accuracy of the device relative to its axis of rotation. The frictional force produced at the points of contact between the magnetic supports and the contact ring, which inhibits rotational movement of the rotor, is significantly reduced by the vibration of the contact ring itself transmitted from an electrically excited piezo-ceramic element. The device does not use a bearing support for rotor positioning, which greatly simplifies the overall system design and eliminates possible positioning accuracy errors.

The invention is explained in the drawing.

the device consists of a fixed base 1 on which a ring-shaped piezo-ceramic member 3 with a contact ring 4 is mounted on three planar elements 2 with two abrasion-resistant supports 5 and a small friction support 6 with a compression spring 7 and three thin supports 8 low friction material contact with rotor 9. The supports 5 on the piezo-ceramic element 3 with the contact ring 4 are arranged at an angle of 120 ° with respect to the center.

The device works as follows.

By connecting a high frequency electrical signal with a phase difference to the electrodes of the piezo-ceramic ring member 3, the excited wave vibrations excited therein are transmitted to the two abrasion-resistant supports 5 of the rotor 9 and the low friction support 6 which is pressed by the spring 7. to rotor 9 and provides a continuous radial bushing. The rotational motion is formed by the frictional force between the friction-resistant radial supports 5 and the oscillating excited contact ring 4, whose lateral annular surface moves all points on elliptic trajectories caused by the effect of a traveling wave. The resilient clamp of the support 6 ensures an even distribution of forces in the radial direction between the support 5 and the lateral annular surface of the contact ring 4, which results in an even rotation of the rotor 9. In this way, the rotor 9 begins to rotate. The magnetic supports 8, coated with a thin layer of low-friction material (phoroplast), continuously pull the rotor 9 against a precisely machined flat surface of the contact ring 4, which ensures positioning accuracy in a plane perpendicular to the axis of rotation of the rotor 9. All this ensures the positioning of the positioning object (not shown) moving with the rotor. When a high frequency signal is applied to the electrodes of the piezo-ceramic element 3, the rotor 9 is rotated in a direction XY. In order to change the direction of rotation of the rotor 9 (propagation direction of the wave traveling in the piezoceramic element 3), opposite phases electrical signals are applied to the electrodes of the piezoceramic element 3

Compared to the prototype, the new set of structural elements is due to the fact that the ring-shaped piezo-ceramic element with contact ring and supports transmits rotational motion and centers the annular rotor with respect to its axis of rotation and perpendicular to its axis of rotation. This eliminates slack and at the same time increases the accuracy of positioning.