| 摘要 |
PCT No. PCT/JP90/01112 Sec. 371 Date Jul. 13, 1992 Sec. 102(e) Date Jul. 13, 1992 PCT Filed Aug. 31, 1990 PCT Pub. No. WO91/03724 PCT Pub. Date Mar. 21, 1991.The present invention is directed to a system for automatically shifting a measuring range equipped in a surface area measuring device. The system for automatically shifting the measuring range is provided with an output value determining circuit receives a signal for detecting a flow rate of supply gases to be outputted from means for measuring a flow rate of supply gases for detecting an amount of the supply gases to be supplied to a sample cell and a signal for detecting a flow rate of discharge gases of the discharge gases to be outputted from means for measuring a flow rate of the discharge gases for detecting an amount of the discharge gases to be discharged from the sample cell, generates a signal for shifting the gain of an amplifier to a low level during a period for desorption of the gases when a differential signal to be outputted from the amplifier for amplifying the difference between the signal for detecting the flow rate of the supply gases and the signal for detecting the flow rate of the discharge gases, and generates a shift signal for shifting the gain of the amplifier to a high level during a period for desorption when the differential signal to be outputted from the amplifier is smaller than a value set for the gain of the amplifier.
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