| 摘要 |
1,120,413. Measuring displacement of movable members. ING. C. OLIVETTI & C. S.p.A. 8 Oct., 1965 [8 Oct., 1964], No. 42721/65. Heading G4H. Apparatus for measuring the displacement of a movable member B (Fig. 1) with respect to a fixed member 1 comprises a counter 10 the contents of which are converted into analogue form and continuously compared with the analogue position of the movable, member to supply an error signal to control the counter. The counter may operate with different counting speeds depending upon the speed of displacement of the movable member. In the form shown the movable member is fixed to the secondary winding 5 of a position measuring transformer T. The number in the counter 10 is fed in binary coded decimal form to a digital to analogue converter 9 receiving A.C. clock pulses from an oscillator 12 so that on output leads 7, 8 sinusoidal signals having maximum amplitudes proportional to the sine and cosine of the angle represented by the count in the counter 10 are obtained. These signals induce on output terminal 13 of the transformer T a sinusoidal signal having a maximum amplitude proportional to the difference between the position of the movable part and the position represented by the digital information in the counter. This analogue error signal is applied to a threshold circuit 23 (which determines the error sensitivity level for the apparatus) to trigger a bi-stable element 32 if an error signal higher than the threshold level is revealed. The signal is also applied to a separator circuit 22 which supplies the positive and negative half waves of the error signal on its output terminals 22S and 22N respectively to gates 26, 27 controlled by clock pulses to energize or deenergize respectively a bi-stable element 31 to give an output on lead 33 or 34 respectively If the error signal is higher than the sensitivity level of threshold circuit 23 gates 36, 37 are enabled to pass a signal from bi-stable element 31 on either lead A or lead I to indicate a forward or backward count in the counter 10. The error signal on lead 13 is also fed to a further threshold device 21 which is triggered if the difference between the position represented in the counter and the actual position of the movable member is greater than 0À1 mm. to give an output on either lead 21S or 21N to indicate whether the counter should count in units or tens. The counter 10 may comprise more than two decades, a corresponding increase in the number of threshold circuits 21 being then necessary. A further counter 42 is incremented by the pulses applied to counter 10. |
