1,116,418. Component testing. MICRO TECH MFG. Inc. April 20, 1966 [April 21, 1965], No. 17231/66. Heading G1U. A device for successively testing a number of dice formed on a semi-conductor wafer comprises a means for moving the wafer beneath a test probe so that the probe successively tests each die (e.g. for open and short circuit) and a record card which is moved beneath a punch in synchronism with the movement of the wafer. Detection of a faulty element on the wafer results in the generation of a signal which actuates the punch to record a fault in a position on the record card corresponding to the position of the element on the wafer.

981,447. Electron microscopes; electrostatic holding devices. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. Aug. 26, 1963 [Aug. 29, 1962], No. 33693/63. Headings H1D and H1P. An electron microscope is provided with an object stage in the form of a heat apertured disc 6 within an opening in which the object 8 is arranged and by means of which the object is movable in any lateral direction, together with at least one body 19 of semi-conductor material connected to the object stage 6 and arranged to contact a stationary part 11 of the microscope, the arrangement being such that, when a voltage is set up between the stationary part 11 and a conductive layer 22 on that surface of the body 19 remote from the part 11, electrostatic forces between the body 19 and the part 11 clamp the object stage 6 in such a manner as to prevent axial movement thereof. Suitable semi-conductor materials are slate, marble, agate and certain ceramic synthetic materials having a resistivity of approximately 1010 ohm-cm. In the embodiment shown an annular block 19 of agate provided with a vapour-deposited layer 22 of silver is rigidly connected in an annular groove 20 of the disc 6 with the interposition of a coating 21 of insulating material. A battery 27 and switch 28 are connected between the conductive layer 22 and the stationary part 11 by way of a lead 23 and the wall 13 of the microscope housing. Specification 824,903 is referred to.

978,143. Electric meters; electric bridge circuits; liquid level measuring apparatus; indicating apparatus. BENDIX CORPORATION. March 14, 1963 [March 26, 1962], No. 10212/63. Headings G1J, G1N, G1Q and G1U. [Also in Divisions G4 and H3] The output voltage of a capacitive liquid level measuring bridge uses a circuit comprising a number of transistors of opposite conductivity type are arranged in cascade such that as the D.C. input signal rises the output voltage first rises and then falls. Fig. 1 comprises two such cascades in succession so that the final output voltage rises and falls twice. It is explained mathematically that so long as the signal voltage is below the level at which the respective output transistors 59 and 72 saturate the gain of each circuits is 2 but when they saturate the output voltage (e.g. E2) is related to the input voltage (e.g. E 1 ) by the relation E 2 = V - 2E 1 where V is the supply voltage. The circuit is used to measure the voltage from a liquid level indicator Fig. 3. The liquid level measuring capacitance 81 is connected in a capacitive bridge fed with alternating current from source 84 and having its output amplified at 85 rectified at 86 and 90 and then applied across a potential variable capacitor 83 in the form of a semi-conductor diode so as to balance the bridge, isolating chokes being provided to separate the A.C. path from the D.C. path. Rectified output from the amplifier is fed to a first meter 93 calibrated in metres and through a folding circuit similar to Fig. 1 to a meter 95 calibrated in decimetres. As the level of the liquid rises from 0 to 1 metre the pointer of meter 93 moves clockwise from 0 to 1 and the pointer of 95 moves in clockwise direction from 0 to 10. A further rise of 1 to 2 metres increases the reading on 93 from 1 to 2 but, as the output of the folding-circuit is now falling, causes the pointer of meter 95 to rotate in an anticlockwise direction towards its initial position, readings being taken from the inner scale. Further rise from 2 to 3 metres causes the pointer of metre 95 to move clockwise again while the rise from 3 to 4 metres causes pointer of metre 95 to return in an anticlockwise direction.

The position and/or speed detector includes a data carrier (2) with at least one track (S) containing track information segments (Ai). A sensor with signal processing circuitry senses the information on the track. The track segments are made of electrically conductive, non- magnetic material and are separated by zones (Zi) of reduced electrical conductivity. The sensor arrangement inductively detects the magnetic fields (M) associated with the eddy currents generated in the track segment. The sensor includes a thin film magnetometer or gradiometer.

1,005,343. Wave guide switches. ALBISWERK ZURICH A.G. Feb. 15, 1963 [Feb. 16, 1962], No. 6153/63. Heading H1W. [Also in Division H4] A single antenna is coupled to both a transmitter and a receiver via impedance transforming networks which contain semi-conductor diodes acting to give the desired high or low impedance. In Fig. 1 the lines A, S, E lead to the antenna, transmitter and receiver respectively. The impedance transforming network across the transmitter comprises lines 9, 10, which are of a length (2n+ 1)#/4 equal to an odd number of quarter wavelengths of the transmitting frequency connected at their ends by diodes 11, 12 inanti-parallel. The line 8 between this network and line A is also of length (2n+ 1)#/4, similarly the network leading to the receiver comprises lines 2, 3 of length (2n+ 1)#/4 and diodes 5, 6. When the trans- mitter S produces an R.F. pulse the diodes 5, 6, 11, 12 conduct in the appropriate half cycles presenting low resistance at the ends of the lines. This means that the input impedance of the branches are high and little energy is lost. On receipt of a pulse by the antenna the diodes are non-conductive because the lower energy of the received pulse is below their threshold voltage. The diodes therefore present high resistance at the end of the lines. The input impedance for lines 2, 3 is low while that for lines 8, 9, 10 is high and so the received energy passes to the receiver. Single diodes in each branch may be adequate in some cases. In order to receive higher signal energies the diodes may be back biased during reception and forward biased during transmission. An alternative embodiment is shown in Figs. 2A and 2B in which oscillatory circuits with zero impedance at the transmitter frequency are used. In the receiver line coupling (2A) the diodes 21 are so connected that they short circuit the input of the receiver for transmitted signals but open the input for reception. In the transmitter line coupling (2B), however, the diodes 25 and 28 provide a signal path during transmission but break the path during reception.

1,188,933. Dosimeter. SCIENCE RESEARCH COUNCIL. 22 Nov., 1967 [22 Aug., 1966], No. 37438/66. Heading H5R. A dosimeter comprises a container having a substantially constant volume under the conditions of measurement employed, a solid material within the container, which material when irradiated by the radiation to be measured, evolves a gas in a quantity related to the radiation dose and means to indicate the pressure within the container. The material exemplified is polyethylene in the form of a powder or as a thin film, e.g. 0À003 inch in thickness, the film being inserted in the container as a roll. The pressure indicating means may be a Bourdon gauge communicating with the interior of the chamber, or the container may be closed and the pressure be indicated by a strain gauge associated with the wall of the container. As a variant on this alternative, one wall of the chamber may be constituted by a diaphragm and movement of this diaphragm may be used to indicate the pressure in the container.

1,269,634. Semi-conductor devices. NATIONAL RESEARCH DEVELOPMENT CORP. 10 June, 1969 [12 June, 1968], No. 28027/68. Heading H1K. A radiation detector comprises a slab of semi-conductor material having a PIN structure and having slots dividing opposite major faces into parallel ribs, the ribs on one face extending transverse to those on the other face, each slot extending to such a depth that it intersects the junction between the respective P- or N- type region and the I-type region. As shown, Fig. 1, a wafer 1 of P-type Ge doped with Ga has a series of parallel slots 5 sawn in one face to form ribs 3 and is etched and ultrasonically cleaned to remove damaged material. A lithium-in-oil suspension is applied to the unslotted face of the wafer which is then heated to diffuse-in the lithium to form an N- type region with an N+ -type surface layer. The PN junction formed is reverse biased to cause the lithium ions to drift-in to form an I- type region 6 between the P- and N-type regions. Slots 4 extending at right angles to the slots 5 are then sawn in the upper face of the wafer to form ribs 2. The wafer is then etched and quenched in an aqueous solution of CaCl 2 , these steps being performed in such a manner that both sides of the wafer are exposed to the fluids. This may be achieved by using a stoppered funnel, Fig. 3 (not shown), or by supporting and rotating the wafer in the etch by means of a nylon clamp engaging the edges of the wafer. The wafer is then given a known clean-up drift. The ribs 2 and 3 are contacted by applying an In-Ga eutectic to the surfaces and pressing on to each face a flexible insulating base, e.g. of fibreglass or plastics material, carrying goldplated contact strips tinned with indium. The In-Ga euteetic alloys to the P-type ribs 3 to provide a low-resistance P-type surface layer. The process steps are controlled so that the sets of grooves 4, 5 intersect the NI and PI junctions respectively, to form an array of PIN diodes with co-ordinate connections. A gamma-ray camera. Fig. 2 (not shown), comprises a PIN diode array mounted with its lower face ribs (3) in thermal contact with a. plate (13) cooled by liquid nitrogen. A bias supply is connected via resistors. (8, 9) to the ribs (2, 3) so that the diodes are reverse biased. A gamma-ray source is viewed through a parallel hole collimator (7) the holes of which are aligned with the diodes of the array. Incidence of a gamma ray on a diode produces pulses at those electrodes. connected to the two ribs the intersection of which defines the diode. These output pulses are amplified and applied to a logic circuit which provides an output indicating the position of the point of the array on which the gamma ray impinged.

1,045,846. Semi-conductor devices. SIEMENS & HALSKE A.G. Sept. 28, 1965 [Sept. 29, 1964], No. 41103/65. Heading H1K. [Also in Divisions G1 and H4] An overload protection device is provided for a transducer suitable for use in a microphone and which is of the type having a pressure-transmitting stylus bearing on a semiconductor member such as a PN junctioncontaining piezo-resistive body. This body is mounted on an electrode plate which in the non-loaded transducer is held against an adjustable limit stop by a spring opposing pressure applied by the stylus. When the load on the stylus exceeds the rest pressure in the spring the latter yields to reduce the stress on the semi-conductor. The region of contact between the stylus and semi-conductor may be surrounded by a viscous medium to lessen the rebound impact if the stylus should lift momentarily from the semi-conductor. The mass of the semi-conductor and electrodes is made small so that the inertia forces on acceleration are preferably less than 10% of the rest force in the spring.