Abstract: An electrodeless discharge tube containing a fill which comprises a metal carbonyl complex. Such a complex will be sufficiently volatile to produce a vapor pressure in a discharge tube in which a discharge can be generated. The discharge so generated emits a mixture of visible and infra-red radiation.

Abstract: An apparatus for monitoring the marking of a recorded signal includes a data store containing marking information and a code selector for selecting any one of three orthogonal codes for marking the recorded signal and a demodulator for demodulating the marked signal and comparing this with the orthogonal codes. The demodulated marked signals are then fed to matched filters and accumulators wherein the marking process may be repeated dependent upon the value of the accumulation.

Abstract: Coating apparatus for a thin plastics web comprises a coating deposition station for applying a coating to the web by vapor deposition and a support for supporting the web at the coating deposition station. The apparatus includes a device for urging gas into the region where the thin plastics web converges with the support to improve the thermal coupling between the web and the support and also to reduce the coefficient of friction between the web and support. The gas enables the coating to be applied by vapor deposition at coating speeds of up to 90 meters per minute without deformation of the thin plastics web.

Abstract: A thermal imaging device includes an array of pyroelectric detector elements, supported by an array of pillars, the pillars also being effective to enable the passage of electrical signals between the detector elements and an electrical signal processing means. Each pillar is separated from a respective detector electrode by an elongate electrically conductive strip. The device includes areas of infra-red absorbant material effective to conduct heat from non-electroded parts of the device into adjacent pyroelectric detector elements.

Abstract: A discharge tube arrangement comprises an excitation device and a discharge tube made of a light-transmissive dielectric material and containing a fill. The excitation device is suitable, when energized with radio frequency (r.f.) power, for exciting surface waves in the discharge tube. The excitation device includes a launcher and a plurality of electrical components associated with the supply of r.f. power to the launcher and constituting at least one of an impedance matching network and a part at least of means to generate r.f. power. This plurality of electrical components is positioned in the launcher between its inner and outer tubes.

Abstract: A discharge tube arrangement includes a discharge tube containing a fill and means for generating a discharge in the fill from a source of radio frequency (r.f.) power. An electrically conductive structure surrounds the discharge tube. The electrically conductive structure is formed of a plurality of waveguides which extend outwardly from the discharge tube. One or more waveguides has a cross-sectional area that increases with separation from the discharge tube. Each waveguide is dimensioned to support the propagation of electromagnetic radiation above a cut-off frequency.

Abstract: A disposable cartridge for use in a clinical sensing arrangement interfaces electrically with a host instrument capable of responding to electrical signals generated by detector devices incorporated in the cartridge upon exposure to calibrant fluids and/or clinical fluids under examination. The cartridge includes a passage linking a reservoir of calibrant fluid to the detector devices and further linking the device to a closed container for fluid which has been conveyed past the devices. A fluid under test can be introducted into the cartridge through the passage wall at a location disposed between the reservoir and the detector devices.

Abstract: A discharge tube arrangement for use as a light source includes a discharge tube made of a light-transmissive dielectric material and containing a fill. An excitation device for exciting surface waves in the discharge tube comprises an r.f. power generator and a launcher. The launcher is formed as an inner tube, an outer tube coaxial with the inner tube and first and second end walls, at least one of the first and second end walls having an aperture for receiving the discharge tube. A launcher gap extends axially from a first end of the inner tube and there is also a further gap. The outer tube and the first and second end walls form an unbroken electrically conductive path to provide an r.f. screening structure around the inner tube.

Abstract: A discharge tube arrangement comprises a launcher and a discharge tube positioned in part within the launcher. When the launcher is energized with radio frequency (r.f.) power, surface waves are excited in the discharge tube which contains a fill. An electrically conductive structure extends along the discharge tube and is connected to an earth when in use. The structure is separated from the discharge tube by a radial distance such that, in use, the discharge tube produces an increase in total light output over the total light output of a discharge tube not having this structure. The structure comprises an insufficient quantity of material to obscure this increase in total light output.

Abstract: A radio frequency transmission and reception system, for use as an active decoy, includes a receiver 10, a transmitter 12 and a signal generator 20 for providing wideband noise signals for transmission during the interpulse period of pulsed signals transmitted by the transmitter 12. A feedback circuit 21, including an adaptive transversal filter 23 combines signals for transmission with output signals from the receiver to adaptively modify the wideband signals in the signals for transmission so as to render the receiver 10 substantially insensitive to received signals which are derived from the transmitter.

Abstract: A recording drum assembly comprises a cylindrical drive shaft 1, a drum 2, and an annular disc 4 of resilient material, such as spring steel, located between the drive shaft 1 and drum 2 and substantially coaxial with the drum 2. The disc 4, by elastic deformation when engaged by the drive shaft 1, provides axial alignment of the drum 2 and drive shaft 1. A portion of reduced diameter may be provided on the drive shaft 1 to facilitate removal of the drum 2 from the drive shaft. Furthermore, the annular disc 4 may be used to support the drum 2 during machining of the drum outer surface to ensure coaxial alignment.

Abstract: An infra red radiation modulator comprises a p type silicon substrate 1 having spaced n type and p type doped regions 2, 3 having respective doping concentrations of approximately 10.sup.20 and 10.sup.16 /cm.sup.3. A signal source 11 provides a bias voltage between the doped regions 2,3 via electrodes 4 for modifying the concentration of free carriers in the substrate between the doped regions and therefore the response of the modulator to incident infra red radiation. By appropriate control of the bias voltage the modulator can be caused to modulate, chop, filter or spectrally scan the incident radiation.

Abstract: A liquid crystal device comprises backlighting means to provide illumination from the rear for a liquid crystal panel. The backlighting means has a layer of light-transmitting material formed with a prismatic region at one edge and a plurality of light sources of differing chromatic output, located adjacent the prismatic region.

Abstract: An electromagnetic article, such as a responder tag for detection by an electronic article surveillance (EAS) system, is fabricated by forming a deposit of a relatively low coercivity high permeability magnetic material on a substrate 22 under the influence of an applied magnetic field so as to provide the deposit with easy and hard axes of magnetization. During deposition the substrate is subjected to a mechanical tension 32 so as to provide the deposit with an inherent benign strain substantially aligned with one of the axes of magnetization. The inherent benign strain is arranged to dominate any detrimental strain to which the responder tag may be subjected during use, enabling detection by the EAS system to be maintained.

Abstract: A fluorescent lamp for use in aquaria, the luminescent layer in said lamp comprising a mixture of red, green and blue phosphors, the red phosphor emitting predominantly in the spectral region of from 610 nm to 620 nm, the green phosphor emitting predominantly in the spectral region of from 540 nm to 545 nm and the blue phosphor having a peak emission wavelength between 430 nm and 480 nm with the half peak width not exceeding 80 nm, said red, green and blue phosphors being blended to form said mixture in such proportions that the color co-ordinates of the lamp employing said mixture on the CIE chromaticity diagram differ from the point x equals 0.300 and y equals 0.232 in any direction by no more than 10 standard deviations of color matching (SDCM). Aquaria employing such lamps are also disclosed and claimed.

Abstract: A discharge tube arrangement includes a discharge tube of a light-transmissive dielectric material and containing a fill. An excitation device for exciting surface waves in the discharge tube comprises an r.f. power generator and a launcher. The launcher is formed as an inner tube, an outer tube coaxial with the inner tube, and first and second end walls, at least one of the first and second end walls having an aperture for receiving the discharge tube. Means are provided inside the launcher for coupling r.f. power to the inner tube. A body of dielectric material extends from the inner tube to the outer tube, thereby to hold the tubes in fixed relative positions, the body encasing the coupling means.

Abstract: An apparatus for measuring the frequency of an input signal is described. The apparatus uses a quadrature sampling system to obtain values of the instantaneous phase of the signals at a succession of time intervals, the values being converted into cumulative phase values. An estimate of the frequency is obtained by determining the gradient of the straight line which would best pass through a plot of the values of cumulative phase against time.

Abstract: A starter circuit for a discharge lamp includes a current control circuit which initially has a low impedance so as to produce an initial cathode heating current for the lamp. The current control circuit is switched into a high impedance condition by means of a control voltage applied to its gate thereby causing a high voltage striking pulse to be applied across the lamp. A field effect transistor is effective to modify the control voltage to the gate such that the starting circuit is effective to produce a succession of starting pulses across the lamp during each half cycle of a rectified AC supply.

Abstract: A method is provided for addressing a matrix-array type liquid crystal cell with a ferroelectric liquid crystal layer having a plurality of pixels defined by areas of overlap between members of a first set of electrodes on one side of the liquid crystal layer and members of a second set of electrodes on the other side of the liquid crystal layer, each of the pixels having a first and a second optically distinguishable state and a response time for switching between the two states which depends on the potential difference across the liquid crystal layer. The method includes the step of applying a switching pixel waveform to a selected pixel to switch it between the two states. The switching pixel waveform is charge-balanced and comprises a first pulse having a sufficient pulse width and pulse height magnitude to switch the selected pixel and a second pulse contributing to charge-balancing.

Abstract: An electrically resistive track suitable for use as a heating element consists of a thick film including a base metal constituent and a glass constituent. The thick film has in the temperature range of from 20.degree. C. to 600.degree. C. a temperature coefficient of resistance (TCR) less than 0.0050 per degree C. Suitable metal constituents include tungsten, molybdenum, a mixture of nickel and tungsten and a mixture of nickel and chromium.