基本信息
摘要：940,730. Piezo-resistive accelerometers. WESTERN ELECTRIC CO. Inc. Feb. 17,1960 [Feb. 18, 1959], No. 5639/60. Heading G1N. In an accelerometer a single unitary indicating element comprises a central mass with one or more pairs of collinear legs cut from a single crystal of a piezo-resistive substance, which legs are so orientated with respect to the crystallographic axes that the electrical resistances between the respective legs of a pair and an ohmic contact on the central mass vary oppositely when one leg is put under compression and the other under tension. Construction of transducer; Fig. 6 shows an element cut from a single silicon crystal and comprising a spherical central mass 60 and three mutually perpendicular pairs of collinear projecting legs 61, 62; 63, 64; and 65, 66, which are as thin as is compatible with strength and which are attached at their outer ends by enlarged feet to a rigid framework 70, 72. Modifications with two pairs and one pair of legs are described; and the legs may be secured directly to a vehicle instead of to a frame. Details are given as to the proper orientation of the legs in relation to the crystallographic axes in accordance with the material of the semi-conductor. The mass of the central sphere may be increased by loading it with lead, resin &c. Circuit arrangements; Fig.7. The resistances between the respective legs of a pair form adjacent arms, e.g. 161,162 of an A. C. bridge circuit, with an indicator such as 40 showing the component of acceleration in the direction concerned. To compensate for the fact that in practice an acceleration in the direction of one pair of legs may cause resistance variations in the circuits associated with the others, each bridge output diagonal has an adjustable coupling with the output diagonals of each of the other bridges. To remove ambiguity as to the sense of the acceleration, when using a simple circuit with an element having only one pair of legs, an additional meter 208, Fig. 9, sensitive to phase sense may be associated with each input diagonal. Alternatively D.C. bridges may be used. Modifications. Combinations of the single pair of legs elements, suitably orientated, or the double pair of legs form may also be used to obtain response to coplanar multidirectional accelerations. Specifications 881, 832 and 881, 834 are referred to.
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