| 摘要 |
1373922 Electro-physical measurements MANUFACTURE BELGE DE LAMPES ET DE MATERIEL ELECTRONIQUE S A 15 Oct 1971 [15 Oct 1970] 48194/71 Heading G1N A capacitive measuring head used to measure the local weight of a yarn, roving, textile strip or tape 5 which passes between the measuring capacitor is comprised of spaced electrodes 1, 2 the latter being positioned between reference electrodes 3', 3" and guard electrodes 4', 4". Electrodes 2, 3', 3", 4', 4" are made by printed circuit techniques on one face of a circuit board on the opposite face of which is disposed further guard electrodes 8 connected to electrodes 4', 4". A further circuit board is disposed in spaced relation and opposing the first board and includes electrode 1 facing the electrode 2 and further guard electrodes 8 on its opposite face. In operation after balancing the bridge circuit, including electrode 1, measuring electrode 2, reference electrodes 3', 3" and windings n 1 of transformer T, in the absence of the yarn 5 the yarn 5 is passed through the measuring capacitor 1, 2. The resulting bridge unbalance signals across resistor R, having an amplitude proportional to the linear weight of the yarn, is attenuated, detected and passed to a synchronous detector to obtain the capacitive component of the signal. The head may be used to alter the frequency of an oscillator circuit instead of used with a bridge circuit. |
