摘要：

1,101,581. Measuring linear dimensions electrically. STEEL CO. OF WALES Ltd. Aug. 24, 1964 [June 1, 1963], No.17205/63. Heading G1N. The position or a dimension, of an object such as the width C 1 C 2 of a steel strip passing over a roller 2, Fig. 3, is measured by traversing a jet of fluid Y 1 from a probe F 1 across the object, passing a current I 1 from the probe to the object through the fluid, and sensing the break in this current when the jet reaches the edge of the object. The current flows in a circuit comprising a battery 40, an electrical connection to the fluid at a, the jet Y 1 , the object with its roller and supporting frame Z, and a detector 42, the frame being earthed and the fluid supply pipes 20, 21, forming an impedance to earth, represented by R2 (equivalent circuit given in Fig. 4, not shown). The probe itself is heat resistant, and electrically insulated from the fluid supply pipes except via the fluid itself, Fig. 2 (not shown). The probe is driven across the object under test by a motor (7), Fig. 1 (not shown), which also rotates a slotted disc (14) between a lamp (16) and a photo-electric cell (17) to indicate in pulse form the extent of travel of the probe, the width of the object C 1 C 2 being indicated by the number of pulses counted between the start and stopping of current flow in the fluid jet, Fig. 7 (not shown). Errors due to the current being cut off by impurities on the surface of the object are avoided by provision of a second jet which scours the surface, and also by including in the measuring circuits a delay device which prevents the pulse count being stopped by a short duration break in the current. Further arrangements referred to for measuring dimensions such as width or thickness include: a plurality of fixed jets arranged to be sequentially operated to effect a scanning motion; a localized scan with respect to only the edges of the object being measured; and a servoscanning arrangement in which a probe follows each edge either closely, or with a hunting motion across the edge.

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