1,015,733. Semi-conductor devices. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. March 18, 1964 [March 21, 1963], No. 11408/64. Heading H1K. [Also in Division H3] A microwave detector arrangement (see Division H3), utilizes a crystal diode 4 which is secured to the upper end of a connecting pin 6 held in a cylindrical conductive shielding sleeve 8 by means of an insulating ring 7. Connecting spring 5 is connected to the sleeve 8, the terminals of the detector being sleeve 8 and pin 6. The assembly is located in a conductive stump 2 provided at one corner of waveguide 1; the pin 6 extends into a vertical bore 9 provided in the middle of the side wall 10, while sleeve 8 lies within a circular aperture in stump 2, leaving narrow gap 11 so as to form a high capacitance which is substantially a short-circuit for microwaves. The gap 11 preferably has a height equal to one-quarter wavelength at the operating frequency.

A microsensor system for determining water vapor content of the ambient atmosphere that uses a thin film suspended ceramic diaphragm structure featuring an embedded, patterned thin film heater, temperature sensor and an external film of an hygroscopic salt stabilized in a water-insoluble, crosslinked polymer matrix and contacting a pair of patterned electrodes which are proximate to the heater. The heater controls a selected electrical parameter of the salt to a fixed, predetermined value, as determined by its electrical characteristics. The dew point of the atmosphere is determined based on the dynamic relation with the salt dehydration temperature.

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.

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.

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.

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.

1,064,646. Semi-conductor pressure transducers. SIEMENS & HALSKE A.G. Aug. 4, 1964 [July 23, 1963], No. 30698/64. Heading H1K. [Also in Divisions G1 and H4] A semi-conductor electromechanical transducer consists of a junction transistor having a pressure-transmitting needle bearing on the emitter electrode or emitter zone of the transistor whose design is such that the current density in the vicinity of the needle is greater than that in any adjacent surface region. The embodiment shown in Fig. 3 is an oxide-protected NPN silicon planar transistor having a drop-shaped emitter zone 13 formed by diffusion into the base zone 12. The aluminium emitter electrode 14 is similar in shape to the emitter region and its pointed end faces a similarly shaped base electrode 15 to provide a region of maximum current density between the electrodes. The needle is so placed that its axis intersects the line between the tips of the electrodes. Placing the point of the needle in a region of highcurrent density compensates for the loss of sensitivity arising from the use of a blunted needle to avoid damage to the semi-conductor surface. The needle is preferably made of sapphire, ruby, or boron carbide, but may possibly be made of the softer molybdenum. The pressure sensitivity of the transistor varies with its collector current. A suitable direct current bias may be applied to the unstressed transistor so that the transistor may be operated in an area of high-pressure sensitivity. To avoid the use of pressures sufficient to give non- elastic deformation of the semi-conductor this means that the transistor should be operated with the lowest standing collector current consistent with a reasonable current gain. To assist in operating the transistor in the chosen area a mechanical bias may be applied to the needle. To obtain high sensitivity the junctions should be very close to the surface of the transistor provided that they are not so close as to be damaged by the needle. This is essential only in the region of the needle and localized etching may be used so that the needle may be placed near the junction. Many uses of the transducer are suggested-an aircraft variometer is described. The Specification gives the relationship between the collector current of a conventional planar transistor with a horseshoe-shaped base electrode and the position of a needle applied at constant pressure to points across the emitter, base, and collector of the transistor.

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.