AUTOMATIC MEASUREMENT-RANGE CHANGEOVER DEVICE FOR SURFACE AREA MEASUREMENT APPARATUS.

摘要

The automatic measurement-range changeover device for the surface area measurement apparatus has an output value discriminating circuit to operate in such manner that fed gas quantity detecting signals output from a fed gas quantity measurer detect a gas quantity fed to the sample cell. Discharged gas quantity detecting signals output from discharged gas quantity detector to detect a gas quantity discharged from the sample cell are inputted into the device. When differential signals outputted from an amplifier to amplify a difference between fed gas quantity detecting signals and discharged gas quantity detecting signals reach a gain of the amplifier. Changeover signals are output for setting a gain of the amplifier at a low level during the period of desorption whereas, when the differential signals outputted from the amplifier is lower than the set value for the gain of the amplifier. Changeover signals are output so that the gain of the amplifier is changed over to a high level during the given period. @(16pp Dwg.No.1/6)@.