1,088,794. Microphones. STANDARD TELEPHONES & CABLES Ltd. Dec. 17, 1965 [Dec. 23, 1964], No. 10172/67. Divided out of 1,088,793. Heading H4J. A microphone or other transducer such as described in Specification 1,088,793, comprising a semi-conductor body having at least two fixed electrodes connected thereto so that an electric current can be caused to flow in the body in a path between the electrodes, has a movable electrode spaced from the body adjacent the current path and capable of establishing a current controlling electrostatic field in the body. Vibration of the movable electrode causes a field effect modulation of the electric current.

1,213,157. Semi-conductor devices. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 28 Jan., 1969 [31 Jan., 1968], No. 4581/69. Heading H1K. A transducer measures mechanical or physical parameters by their effect on the electrical resistance of a whisker of silicon carbide which forms the transducer element. This whisker is grown by recrystallization and/or condensation in a space bounded by silicon carbide in a protective gas atmosphere in the presence of lanthanum, or by the vapour-liquid-solid mechanism with iron in the liquid phase. The whisker is doped with aluminium or boron, and is provided with ohmic contacts of tungsten, or a gold alloy containing tantalum or tantalum and aluminium. Various embodiments of the transducer are described for measuring gas pressure, tensile stress, gas flow rate, temperature, electromagnetic radiation or liquid level in a container.

379,648. Hydraulic accumulators. CAUMONT, H., 14, Rue George Sand, La Varenne-St-Hilaire, Seine, France. April 11, 1932, No. 10307. Convention date, April 13, 1931. [Class 69 (ii).] In hydraulic accumulator apparatus loaded by compressed air, the distribution of liquid is governed by the weight of liquid in the accumulator. The accumulator 1, Figs. 1 and 2, is pivotally mounted at 2, and its other end is connected to a weight 5, which during its upward motion is adapted to pick up weights 7, 8 in succession. The gas space of the accumulator is connected by a conduit 9 to a reservoir 10, and the liquid space by a conduit 11 to conduits 11a, 11b. A valve 16 determines whether a pump 17 is byepassed or delivers to the accumulator, and a valve 14 controls the connection between the accumulator, and the apparatus supplied thereby, said valves being operated from members 19, 20. When the accumulator is in the position shown in Fig. 1, the conduit 11 is closed by a ball 23, Fig. 7, rolling between knife-edged guides 24. A thin film of oil may cover the liquid in the accumulator. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the use of springs instead of counterweights. This subjectmatter does not appear in the Specification as accepted.

938,441. Measuring fill height of containers. INDUSTRIAL NUCLEONICS CORPORATION. July 6, 1961, No. 24563/6 Class 40 (3). In apparatus for determining the fill height of material in containers 18, Fig. 3, by means of a source of penetrative ionizing radiation 30 located on one side of the container and detecting means 32 for said radiation located on the other side of the containers, the detecting means comprise a plurality of elongated detector tubes 33-35 mounted substantially in a plane which also passes through the location of the source and through the level of the desired fill height of the material. In accordance with a first feature of the invention, Fig. 2, the radiation source 30 is located at a distance or close to the path taken by the containers 18, whilst the detecting means 32 is located at a distance b (limited only by the need to maintain a useful signal-to-noise ratio in the detector output), whereby a given change in the fill height of the container extends over a relatively large portion of the radiation flux angle (determined by dimension of the detector aperture c) and the system acquires good resolution. According to a second feature of the invention, Fig. 3, the path between the source 30 and detecting means 32 is inclined at such an angle to the path of the containers that the containers despite being spaced continuously interrupt the radiation. By this means a pulse output is not produced by the detecting means in response to the passage of succession containers and output variations are due only to fill height variations. The detector may comprise three Geiger-Muller tubes 33-35, successively displaced as shown and connected with the outputs in parallel. The source 30 may comprise a radio-active isotope of cobalt arranged as a cylinder or fine wire disposed end on to the desired radiation path, or a thin film of a radioactive isotope of caesium. Reference is made to a system in which the radiation path is perpendicular to the path of containers 18. The detector output may be used to control the apparatus dispensing the material to the containers, reference being made in this respect to Specification 938,442.

883,096. Semi-conductor devices. SIEMENSSCHUCKERTWERKE A. G. July 24, 1958. No. 23902/58. Class 37. The magnetic effect on the wafer produced by the control current in a Hall generator is eliminated either by an additional compensating winding or by a split feed arrangement. Fig. 2 shows a Hall modulator having control current electrodes 5 and 6 and Hall electrodes 7 and 8. A compensating loop 9 is connected via a potentiometer 10 to the control current supply whereby the magnetic field on wafer 4 due to the control current path may be compensated. In Fig. 3 the control current is fed to electrode 5 by two leads 15 in parallel, and potentiometer 13 provides for adjustment so that the magnetic effects of the two leads compensate each other.

1,151,435. Strain gauges. G.V. PLANER Ltd. Dec.5, 1967 [Sept.6, 1966], No.39714/66. Heading G1N. [Also in Division H1] A resistance strain gauge comprises a deformable support carrying a thin film resistor composed of at least one ingredient from each of the following groups: a) chromium, chromium oxide, manganese, manganese oxide b) silicon, silicon oxide. Preferably the atomic ratio of the constituent elements is chromium and/or manganese 1, silicon 0À4 to 7, oxygen 0 to 5, various examples being given together with their resistance characteristics. The support may consist of glass, vitreous silica, ceramic or metal coated with insulating material, the thin film resistor being applied by vacuum or flash evaporation. The resistor may be of meandering form, and terminal areas may be provided by vacuum deposition of chromium and gold. The gauge may be used in pressure and displacement transducers, proximity gauges and accelerometers. Reference has been directed by the Comptroller to Specification 1,069,435.

1,028,747. Transistor detector circuits. ROSEMOUNT ENGINEERING CO. Ltd. Sept. 1, 1964 [Sept. 10, 1963], No. 35740/63. Heading H3T. [Also in Divisions G1 G4 and H2] To obtain a semi-conductor rectifier with low reverse leakage and low charge storage for a measuring. instrument (see Division G1) a low leakage diode and a low charge storage diode are connected in series. Reverse leakage is reduced by cooling a semiconductor diode 4 with a Peltier element.

1,106,402. Engraving. STANDARD TELEPHONES & CABLES Ltd. 24 Feb., 1966, No. 8163/66. Heading B6J. A machine for engraving a semi-conductor slice comprises a ferro-magnetic base-plate 1 supporting a work-table 2 and movable in two directions at right-angles, with respect to a head 5 carrying an engraving stylus 4, by means of two rams each driven by a stepping motor under the control of a tape. The slice is contacted by two probes 10 to detect the electrical parameters of the slice, which are altered by the engraving, until a desired state is attained and sensed, stopping the engraving-machine. Each probe is first located with respect to the slice by moving the base-plate as desired, moving the probe base 11 on a member 9 into contact with the base-plate, releasing the base 11 from the member 9 to which it was held electro-magnetically, and electro-magnetically securing the base 11 to the base-plate. The members 9 are raised and lowered by solenoids 7, 8.