SU1673991A1 - Accelerometer - Google Patents

Abstract

The invention is intended to measure low frequency linear accelerations. The purpose of the invention is to increase the sensitivity of the accelerometer. In the presence of acceleration, the cantilever sensing element 2, made of an electrically conductive material, is disconnected. When the conductive part of the sensing element 2 approaches the interdigital transducer, a partial shorting of the electric field created by the surface-acoustic wave (SAW) occurs. As a result, the frequencies of the SAW generators are changed, and a signal is received from the frequency difference meter, which is proportional to the measured acceleration. 3 il.

Description

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The invention relates to a technique for measuring motion parameters, in particular, to measuring linear acceleration of direct conversion, for surface acoustic waves (SAW).

The purpose of the invention is to increase the sensitivity of the accelerometer.

FIG. 1 and 2, an accelerometer simplified structural diagram is shown; in fig. 3 - its functional block diagram.

The accelerometer has a base 1 on which a cantilever sensing element 2 is fixed, having one degree of freedom relative to the base 1. The upper fixed plate 3 and the lower fixed plate 4 are fixed to the base 1. The plates 3 and 4 are arranged symmetrically with respect to the sensitive element 2, and On their sides, facing the sensitive element 2, are placed delay lines on the interdigital transducers (IDT) 5 and 5.

FIG. 2 using the example of the lower fixed plate 4 shows that the input transducer 6 is located with respect to the output transducer 7 symmetrically with respect to the longitudinal axis of the sensitive element 2 with the wave propagation direction perpendicular to the longitudinal axis of the sensitive element 2. The transducer 6 and 7 4 in a region with a piezoelectric material, such as zinc oxide. IDT 6 and 6 on each of the plates 3 and 4 form a delay line.

On the delay lines on each of the plates 3 and 4, surfactant generators are formed by turning on amplifiers 8 and 81 between the input transducer b and b1 and output transducer 7 and 7 on the corresponding plate (Fig. 3). The outputs of the SAW-generators are connected to the meter 9 frequency difference.

The accelerometer works as follows,

FIG. 2 7

In the absence of acceleration, the frequencies of the SAW generators are equal and the output signal from the frequency difference meter is zero. In the presence of accelerated, perpendicular

of the sensitive element 2 towards one of the fixed plates 3 and 4. When the electrically conductive part of the sensitive element 2 approaches the input and output transducer 6 and 7, the electric field created by the surface acoustic wave partially on the plate 3 or 4 with its effect on the piezoelectric

material in the space between IDT 6 and 7. As a result, the frequencies of SAW-generators change and a signal is output from the output of the frequency difference meter, which is proportional to the measured

Claims (1)

acceleration. The shunting of an electric field in piezoelectric ceramics in the range of movement of the sensitive element can vary within wide limits (it is theoretically possible to change the frequency of the SAW generator from the fundamental frequency to zero). Claims of the invention: Accelerometer, holding a cantilevered sensor element mounted in a housing, delay lines, formed by interdigital transducers, an amplifier connected by inter-output interdigital transducers in each delay line, and a frequency difference meter whose inputs are connected to the outputs of amplifiers, in electrically conductive material, and the delay lines are located on the body on both sides of the console symmetrically about its longitudinal axis with the direction of the acoustic path perpendicular to this axis. Fig.Z