| 摘要 |
PURPOSE:To make it possible to accurately measure the quality of water by such an arrangement wherein the results of calibration of zero and span are fed back to an arithmetic operation circuit every time when a calibration is made, and the constants of an arithmetic operation formula are renewed and compensated. CONSTITUTION:Every time a period of time set by a timer has elapsed, change-over switches 32a, 32b are changed over to the side of calibration C respectively, and a control circut 35 gives a calibration start command to a calibration device, and zero calibration liquid is supplied from a zero point calibration liquid tank to a density detector which makes a measurement. The output of the detector is converted into linear signals by a signal conversion circuit 31 and converted signals pass through the contact point (c) of the change-over switch 32a and enter an output circuit 33 where they are converted into a density value. At the same time, these signals are memorized in memories 38, 40. Upon completion of a zero point calibration, the control circuit 35 is changed- over to span calibration, and similarly signals at that time are memorized in memories 39, 41. Upon completion of calibration operations, an arithmetic operation circuit 36 reads out these memorized values, caliculates values of density and renews and compensates the constants of an arithmetic operation formula. |
