| 摘要 |
744,311. Electric tests. INDUSTRIAL MACHINERY CO., Ltd. Jan. 29, 1954 [Feb. 18, 1953], No. 4525/53. Class 37. [Also in Group XL (b)] In apparatus for measuring weight density or mass per unit area of a material the moisture content of which varies, the output of a radioactive gauge which is relatively slow in its response and which is independent of moisture content, is combined with that of a further gauge, for example a dielectric gauge in such a way as to alter the datum of the further gauge to eliminate the effect of moisture while maintaining the speed of operation of the dielectric gauge. As shown the output of a Beta-ray gauge 4 is averaged by condenser 14 and resistance 13 and fed through a cathode follower valve VI and stored in one of a number of condensers 20 mounted on a rotating assembly. The output of the dielectric gauge 2 which is spaced from the Beta-ray gauge in the direction of movement of the material is also connected to an averaging circuit 15, 16 and applied to the grid of a triode V3. Condenser assembly 20 rotates in synchronism with the movement of the material under test so that when the condenser representing the density of a particular part of the material under test reaches fixed contact 24 the material which produced the change is being examined by the dielectric gauge. This charge is applied to the grid of triode V2 and between the cathode of this valve and V3 is the coil 31 of a polarized relay which if the outputs of the two meters differ due to moisture in the material causes A.C. motor 35 to run in one direction or the other to reposition a potentiometer slider 38 this altering the datum of the dielectric gauge so that an output on line 40 gives the true density of the specimen. In a modification (Fig. 5) the averaged output of the dielectric gauge 41 is fed through a condenser 44 to the grid of a triode 45 while the output of the Beta gauge 42 is fed through a resistance 48 to the same grid, the condenser and resistance having a common connection to the grid. The dielectric gauge produces an output including both direct and alternating components the direct components being eliminated by condenser 44. Condenser 44 and resistance 48 smooth the output of the Beta gauge thus determining the direct potential of grid 45. The values of condenser 44 and resistor 48 may be so chosen that the output across the cathode resistor is effectively the Beta gauge output. Specification 558,491 is referred to. |
