To inspect ampules automatically by the previously explained method, this machine is required to have considerably high sensitivity because foreign particles are in minute size. However, this sensitivity is restricted by the noise in the detecting part, i.e., by the shot noise of the photomultiplier output current. This noise accompanies the photomultiplier output d.c. current and masks the output signals of foreign particles by forming the background noise. For this reason, lowering of the photomultiplier output d.c. levels, in other words, reduction of intensity of the light reflected from the surface of ampule is of importance, but it is extremely difficult to do so in every ampule owing to uneven optical characteristics of each ampule. From the above fact, it becomes apparent that a detection error will occur with this machine when the noise level is considerably high. Besides this error, nother error will occur by another reason or saturation of the photomultiplier output current. Both errors can be successfully avoided by discriminating non-inspectable ampules when their d.c. levels exceed the predetermined d.c. level. Given in this paper are the results of measurement of the output noise and saturation characteristics of photomultiplier, and their relations with the predetermined level for discrimination of non-inspectable ampules.

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A new method has been developed for detecting the height of liquid level in a bottle. Based on the fact that bottled liquid column converges light as a cylindrical lens, while the space and bubbles avove the liquid surface do not, the method utilizes the difference between the refractive indices of the media above and below the liquid surface, which is picked up by a double beam oytical system. This method, free from the existence of floating bubbles, can obtain the level height more conveniently than by the conventional method based on light transmission factor.
With the results of basic experiments, calculations and experiences of plant tests, an inspection apparatus using the phototube which makes the convergence of light correspond to the electric pulse existence was made for brewing industry. Optimum sizes of optical systems, special phototubes which have been developed for this apprratus and electronic circuits which consist of pulse shaping circuit, differentiating circuit, bottle transmission compensating circuit and anticoincidence circuit, serve to eliminate the inevitable error actions of the apparatus. In addition to the report on this apparatus, examples of experimental data are given in this paper.

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When a magnetic field is applied vertically to the direction of the current running through a crystal of semiconductor, a gradient of potential appears at a right angle both to the field and the current as shown in Fig. 2. This phenomenon is called a Hall effect. The electric displacement transducer, as shown in Fig. 1, uses the Hall effect of germanium pellet which is inserted into an ununiform magnetic field. If the pellet moves in right or left direction, the Hall voltage changes by the increase or decrease of magnetic flux which is interlinked to the pellet. The relation of displacement and Hall voltage, as shown in Fig. 8, depends on the shape of Hall pellet and the distribution of magnetic flux. The Hall pellet is sealed with metal capsule so that it is not exposed to the open air and the temperature distribution of the pellet is maintained uniformly. When tests are conducted, the temperature characteristics of the Hall voltage are constant within the range from -40°C to +95°C for 0.3Ω-cm N-type germanium. This transducer is being used as the detector of Yokogawa's new Electronic Control System for flow, pressure, liquid, etc. The characteristics of standard displacement transducer are as follows.
Output: 10mV D.C. for 2mm displacement
Nonlinearity: less than 0.3%
Temperature error: less than 0.5% for -40°C to +95°C
Hysteresis: negligibly small
Figs. 17 to 19 show the differential pressure transmitters applying this displacement transducer which have attained excellent performances.

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