RU2251176C2 - Solid-state electromechanical converter - Google Patents

Abstract

FIELD: optics.

SUBSTANCE: proposed converter designed for operation as actuating device in adaptive optical systems has multilayer stack of plates electrically connected in parallel with double-layer ferroelectric ceramic plate with diffused phase transition. One layer of double-layer plate has slot of depth equal to thickness of this layer. Axes of slots in adjacent double-layer plates are disposed in relatively perpendicular planes.

EFFECT: elongated travel distance of operating element, enhanced time and temperature stability.

1 cl, 2 dwg

Description

The invention relates to optics and is intended for use as an actuator in adaptive optical systems.

Known piezoelectric electromechanical transducer, which is part of the accelerometer [1]. The device contains a multilayer element consisting of piezoceramic plates with metal electrodes connected electrically in parallel. The electrodes have insulating gaps and protrusions for connecting to the patch bus. The monolithic design of the element provides its high rigidity. However, in the case of using an element in the actuator, the presence of insulating gaps causes tensile mechanical stresses at the interface between the electroactive and passive parts of the plate, which significantly reduces the mechanical strength and reliability of the device.

The closest analogue is the sensitive element of the accelerometer [2], in the form of a monolithic multilayer package of piezoelectric plates connected electrically in parallel. In piezoelectric plates from the side of one of the electrode surfaces, metallized grooves are made, the depth of which is 0.3 plate thickness. The grooves are diffusely filled with metal patch bars. The device has a low relative transverse conversion coefficient when operating as part of a piezoelectric accelerometer.

However, when operating as an actuator, the known electromechanical transducer does not have a sufficiently high controllable deformation. Controlled deformation in a piezoelectric electromechanical transducer is proportional to the electric field strength in its constituent plates. The value of the electric field strength in an electromechanical converter made of a ferroelectric with a diffuse phase transition is especially important [3]. The controlled deformation in this material is proportional to the second degree of electric field strength. One way to increase the electric field in a known device is to reduce the thickness of the plate is limited by the mechanical strength of the plate, weakened by the groove. Another way - increasing the control voltage - is often unacceptable due to the complexity of the electronic equipment of the control system and reducing its reliability.

The inventive solid-state electromechanical transducer can significantly increase the displacement of the working body of the optical system by increasing the controlled deformation of the transducer.

The indicated technical effect is achieved in that in a solid-state electromechanical converter, which includes a multilayer package of electrically parallel ferro-ceramic plates with electrodes and metallized grooves, diffusely filled with metal switching buses, and an electrical connector for connecting to the control system, the package consists of two-layer plates made of ferroelectric ceramics with a blurred phase transition, one layer of each two-layer plate contains a groove with a deep bina equal to the thickness of this layer, the two-layer plates are oriented in the package so that the layers with grooves alternate with the layers without a groove, and the axis of the grooves of the adjacent two-layer plates are located in mutually perpendicular planes.

The creation of a solid-state electromechanical converter was made possible thanks to a combination of a new design and a new material of ferroceramic plates making up the package. The two-layer design of the plate allows you to implement the principle of separation of functions between layers. The groove layer effectively and reliably performs a contact function. An electroactive layer without a groove can be brought to a thickness of the order of 100 micrometers without sacrificing mechanical strength, which can significantly increase the electric field strength. The greatest effect of increasing the electric field is achieved in ferroelectric ceramics with a diffuse phase transition [3], with a quadratic dependence of the controlled deformation on the electric field. In addition, this material has a very low temperature coefficient of linear expansion and low aging due to the absence of a domain structure. The absence of a polarization process increases the reliability of the device, since mechanical stresses occurring in a polarized piezoelectric packet are excluded. The symmetrical cross-shaped groove system provides the same bending stiffness of the transducer in two planes, which extends the range of operating frequencies. The combination of all these properties allows you to create a highly sensitive electromechanical transducer with high time and temperature stability for use in adaptive optical systems.

The invention is illustrated by the following description and drawings. Figure 1 shows a General view of a solid-state electromechanical transducer and a diagram of electrical connections. Figure 2 presents a General view of two adjacent two-layer plates that make up the package.

The device comprises a package 1, consisting of two-layer plates 2 made of lead magnon-niobate - ferroelectric ceramics with a diffuse phase transition. Layers 3, 4 of the two-layer plate 2 are equipped with electrodes 5, 6, 7 and are rigidly connected by diffusion welding.

In the first layer 3, a groove 8 is made (8.1 and 8.2 in FIG. 2), the depth of which is equal to the thickness of the layer 3. The groove 8 is metallized. Two-layer plates 2 are rigidly connected to the package 1 by diffusion welding. In this case, the plates 2 are oriented in the package 1 so that the layers 3 with a groove alternate with layers 4 without a groove, and the axes of adjacent grooves 8 are located in mutually perpendicular planes (8.1 and 8.2 in figure 2).

The grooves 8 are diffusely filled with metal switching buses 9, which are connected via conductors 10,11 through an electrical connector 12 to the output amplifier of the control system 13.

The package 1 is rigidly connected to the final ceramic plates 14, 15. The plate 14 performs the function of the base of the electromechanical transducer and is rigidly fixed in the housing of the optical system. The plate 15 through the pusher 16 is connected to the working body 17 - an element of a partitioned mirror or mirrors with a controlled surface shape.

The device operates as follows. The control signal from the output amplifier 13 enters through the connector 12 and conductors 10, 11 to the switching bus 9 of the two-layer plates 2. In this case, an electric field arises in layers 4, the intensity of which is inversely proportional to the thickness of layer 4. Due to the electrostrictive effect, layers 4 of all two-layer plates are deformed 2. The electrostrictive deformation of ferroceramics with a diffuse phase transition is proportional to the second degree of electric field strength. The total deformation of the package 1 is transmitted through the pusher 16 to the working body of the system 17.

The new design of the electromechanical transducer, which allows one to create a high electric field strength in an electroactive material, and the choice of a ferroelectric material that effectively converts a high electric field strength to a deformation that exceeds the controlled deformation of known piezoelectric materials, made it possible to create a highly efficient actuator for adaptive infrared optical systems, in which require significant movement of the worker Gana commensurate with the wavelength of the applied laser radiation. Due to the additional technical effect - high temporal and temperature stability - the new device will find application in laser optical systems for aerospace purposes.

Sources of information

1. A.S. USSR No. 1682938, M.C. G 01 P 15/09, 1991.

2. RF patent No. 2150117, M. Cl. G 01 P 15/09, 1998.

3. Venevtsev Yu.N. and others. Ferroelectric and antiferroelectrics of the barium titanate family. - M.: Chemistry, 1985, p. 165.

Claims (1)

A solid-state electromechanical converter, comprising a multilayer package of electrically parallel ferroceramic plates with electrodes and metallized grooves, diffusely filled with metal switching buses, and an electrical connector for connecting to a control system, characterized in that the package consists of two-layer plates made of ferroelectric ceramic with blurred phase transition, one layer of each two-layer plate contains a groove with a depth equal to the thickness of this layer I, dual-layer plates are oriented in the package such that the groove layers alternate with layers without the groove and the axis of adjacent slots bilayer plates arranged in mutually perpendicular planes.

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