Abstract: A thermal detector arrangement includes a number of channels, each including a collimator for collimating incident radiation to a respective optical filter. Each optical filter has a respective radiation passband characteristic with one having a passband spanning the passbands of all of the other optical filters. The radiation passed by each optical filter is passed to a thermal detector, which preferably is in the form of a thermally isolating membrane acting as a radiation absorbent cavity and supported by a semiconductor substrate. The output signals from the thermal detectors are multiplexed, amplified by an amplifier having voltage offset compensation and digitally processed to provide an indication of a fire to be sensed.

Abstract: A tungsten halogen lamp producing infra red radiation, for example for cooking or heating, has an envelope of high silica content material sealed at each end by a pinch seal. A gas fill is at a room temperature pressure of 250-750 mm Hg. A portion of the envelope at each end is clear and the rest contains an opacifier which reduces transmission of visible light. A suitable opacifier is red, being produced by the reduction of copper oxide dispersed in the high silica content material. The envelope is produced by butt joining clear end sections and a tube of material containing opacifier.

Abstract: A luminaire is disclosed comprising a fluorescent plastics outer sleeve having a configuration such that a high proportion of the fluorescent light generated within the sleeve is emitted as visible light. The sleeve includes a fluorescent dye, which dye is excited by a blue phosphor discharge.

Abstract: A ballast circuit includes a load circuit. A reservoir capacitor is effective to supply charge to the load circuit. A capacitive charge pump circuit is effective to transfer charge from a charge pump capacitive circuit to the load circuit and to the reservoir capacitor. The load circuit includes the primary winding of a transformer. A secondary winding of this transformer is for connection across a discharge lamp. In operation of the ballast circuit, the primary winding of the transformer drives the capacitive charge pump circuit.

Abstract: A method of operating a display comprising a lattice of pixel elements, includes the step of time-multiplex addressing collections of pixel elements. This addressing step includes using a first shift register means to designate operation of a second shift register means to select a function to be performed. If the second shift register means is in bypass mode, then the first shift register means is effective as a mask to specify which of the stages in the second register means should be bypassed, and allows non-sequential group addressing of the pixel elements. Such an arrangement of first and second shift register means is suitable for use in controlling the addressing of collections or rows of pixel elements; the function to be selected by the second shift register means is the strobing of the collections or rows.

Abstract: A thermal imaging device is described including an array of pyroelectric sensor elements. Each element is at least partially supported by a respective pillar of an intrinsic polymer material. The pillars provide an electrical path between the elements and a signal processing means.

Abstract: A method of addressing a display device comprising a matrix of separately operable pixels is provided. The method comprises the step of applying across a given pixel a voltage waveform comprising a latching pulse and an auxiliary pulse of amplitude smaller than the latching pulse. The amplitude of the auxiliary pulse is modulated to determine the latching effect of the latching pulse.

Abstract: In a liquid crystal display, each pixel is formed of four separately energizable areas which have relative light outputs in the ratio 1:2:4:8 respectively, thereby allowing a range of 16 grey levels to be achieved by appropriate selection of areas. Each of the areas has a number of segments, which are spaced-apart but concentrically arranged, in order to have the same average position, so that different bit patterns cause the pixel to change brightness only, without any apparent positional change.

Abstract: A display device is formed by a matrix of surface-stabilized bi-stable ferroelectric liquid crystal elements each being separately settable by a matrix driver. To provide brightness control or color in the display, all the elements of the matrix are set in accordance with a portion of a signal for display and the amount of light passing through the matrix for that setting is controlled in accordance with the binary significance of the respective portion of the signal. This control is produced by varying one of the activation duration or intensity of a light source, such as sets of fluorescent tubes in accordance with the binary significance of the brightness information in the input signal. Half of the frame time (T) is used for the numerous setting operations on the matrix of elements and half is used for the backlighting operations of the various settings.

Abstract: A mounting arrangement is provided for mounting a lamp fitting on a planar support, it comprises: a plurality of carrier means secured to the lamp fitting, each carrier means having at least one linear series of parallel tooth members; and a plurality of support members, each support member including means for locating the support member on a respective carrier means and at least one engagement surface for engagement with a chosen tooth member such that in use of the mounting arrangement, the engagement surface is maintained in engagement with the tooth member by the weight of the fitting acting on the engagement surface.

Abstract: A ballast circuit for the operation of a discharge lamp includes a bridge rectifier. A capacitive energy storage device and a load circuit are connected in series across the bridge rectifier. A charge circuit provides charge to the capacitive energy storage from the load circuit in a potential so as to add to the potential from the outlet of the bridge rectifier.

Abstract: A method of manufacturing a color filter for a liquid crystal cell comprises forming a plurality of patterns, each of a respective dye intermediate material, on a carrier element. The patterns of dye intermediate materials are then brought into contact with a substrate layer, supported on a glass substrate, under the application of heat and pressure. The substrate layer, such as a polyacrylonitrile layer, contains free acid groups which interact with the dye intermediate materials to form the colors of the color filter in the substrate layer. The method permits the actual formation of the colors on the substrate to be effected in a single alignment step, minimizing wastage of the relatively expensive glass substrates. Furthermore, as the dyes providing the colors of the filter are chemically part of the substrate layer, they are very resistant to leaching by the liquid crystal materials.

Abstract: A signal identification system, suitable for producing an identification code on a sound track recording is described. The system includes an encoder 209 effective to eliminate a variable sequence of frequency bands from an audio signal and insert a sequence of code signals into the frequency bands. As the sequence of frequency bands varies throughout the sound track recording, the presence of the code is difficult to detect.

Abstract: A ferroelectric liquid crystal device has a first state (T.sub.X1) of maximum transmission, a second state (T.sub.X2) of minimum transmission and a value of voltage pulse width (t.sub.S) and voltage pulse height (V.sub.S) sufficient for a switching pulse to switch the cell from the first state (T.sub.X1) to the second state (T.sub.X2) or vice versa. A method of controlling the transmission of electromagnetic radiation through the ferroelectric liquid crystal device comprises the step of applying, for a time period greater than said value of pulse width (t.sub.S), a plurality of consecutive controlling pulses of one polarity. Each controlling pulse is itself of insufficient pulse height and pulse width to switch the cell from the first state (T.sub.X1) to the second state (T.sub.X2) or vice versa.

Abstract: An electrodeless discharge tube containing an ionizable fill, the tube having a first portion for insertion in a launcher and a further portion separated from the first portion by a partition wall. Hence a discharge can be excited in the further portion because a surface wave can propagate through the wall separating the first and further portions.

Abstract: A drive circuit comprises a first waveform generator and a second waveform generator. Each waveform generator is capable of generating at least two voltage states and the instantaneous voltage of the first waveform is never less than that of the second waveform by more than a defined amount. The circuit further comprises a plurality of means to produce respectively a plurality of output waveforms by selectively switching to either the first waveform or the second waveform and a gate array to control the selective switching. The arrangement is such that each of the plurality of means to produce respectively a plurality of output waveforms is capable of producing an output waveform having at least four voltage states. The drive circuit produces a plurality of outputs suitable for driving a matrix-addressed display.

Abstract: A sealing composition is provided for joining crystalline ceramic or cermet parts, e.g. in an arc tube for a discharge lamp. The sealing composition comprises, as starting materials, a mixture of alumina (Al.sub.2,O.sub.3), silica (SiO.sub.2) and magnesia (MgO), the mixture comprising in the ranges of from 22% to 24.5% by weight of Al.sub.2 O.sub.3, from 45.5% to 49.5% by weight of SiO.sub.2, and from 26.0% to 32.5% by weight of MgO. The sealing composition contains less than 40% by weight, of the mixture, of the crystalline phase .alpha.-Cordierite when subjected to the following test procedure.(i) sintering the mixture at 1200.degree. C. for 10 hours to produce a friable lump which is crunched and heated at 1550.degree. C. for 2 hours while the glass is in a molten condition;(ii) pouring the resulting material into water to form a brittle frit and, after drying at 160.degree. C., grinding the glass to a powder particle less than 180 .mu.

Abstract: A single channel optical recording system is described, which system does not require a second rotating optical element. The system uses focus error correction components located outside the rotating drum. Light transmitted to and from the drum is at all times axially symmetric, thus circumventing the problem of image rotation. Lateral error correction takes place entirely within the drum, requiring only the transmission of d.c. electrical power across the rotating interface. Preferably the physical distribution of optical components within the drum is symmetric to ensure mechanical balance. A dual beam tracking system to write data in compact form in a single-channel optical tape recorder is also described. The tracking is achieved in the drum and without any additional optical elements. Passive or active alignment of the two beams before entering the drum is achieved using an extended anamorphic prism pair and without introducing additional optical surfaces into the beam path.

Abstract: A display device has a lattice of pixel elements each selectably settable. A method of operating the display device comprises the steps of receiving a signal representing a picture for display during a display period and illuminating the lattice to produce, during a first interval within the display period, a first light output from the lattice having a first predetermined color characteristic and to produce at least one additional light output from the lattice. Each said additional light output has a different predetermined color characteristic and a respective interval within the display period separate from the first interval. The method further comprises the step of time-multiplex addressing blocks of pixel elements a plurality of address times during each interval.