| 摘要 |
1,119,213. Measuring pressure electrically. TOYOTA CHUO KENKYUSHO, K. K. Sept. 29, 1965 [Sept. 29, 1964; Oct.29, 1964], No.41313/65. Heading G1N. [Also in Division H1] A piezo-resistive transducer has two resilient diaphragms mounted parallel to one another and, with a side wall, forming a capsule within which the semi-conductive transducing elements are mounted. At least one element is attached to each diaphragm. The capsule is placed in a medium the pressure of which is to be measured. By the use of diaphragms of unequal thickness in association with a bridge circuit to provide an output representing the difference between the signal of the indentical transducers on the two diaphragms, the effect on the output of the variation of semi-conductor resistivity with temperature is eliminated. The transducers of Figs. 5-7 (not shown) and of Figs. 15-17 (not shown) and 18 have two rimmed diaphragms 21,24. Typically, one diaphragm may be three times the thickness of the other. They may be of carbon-steel and carry monocrystalline N-type germanium elements 27a-d bonded to the diaphragm with an insulating adhesive such as an epoxy resin. The leads 28 are brought from the capsule through the side wall and sealed thereto with epoxy resins. A tube 30 which also emerges may be open to the atmosphere or may be fed from a source of reference pressure; alternatively a spring-device may be placed between the diaphragms to tend to separate them, its strength being chosen to suit the pressure range to be measured. Figs. 11 and 12 (not shown) illustrated methods of fixing the rimmed diaphragms together. Figs. 13 and 14 (not shown) show constructions in which plane diaphragms are attached to a separate annular wall. In the embodiments of Figs. 5-7 and 11-14 the diaphragms are effectively edge clamped and for maximum output the transducing elements should not lie across a circle of neutral stress in the diaphragm. Constructions in which the diaphragm is effectively freely supported and so have no circle of neutral stress allow the use of longer transducing elements, in that of Figs. 15 to 17 (not shown) and 18 the rims of the two diaphragms are grooved to prevent effective peripheral clamping of the diaphragms. |
