Abstract: A required visual signal for direct observation is produced from a first source of light in the presence of a second source of light, such as ambient light. Light is transmitted from the first source to a defined surface or defined region distant from the first source. A means for modulating light is operated between at least a first mode and a second mode. This operation is synchronized with a varying of the intensity of at least one of the sources of light at or above a given frequency equal to or greater than the critical fusion frequency for the size and luminance of the required visual signal. When the modulating means is in the first mode, this allows the required visual signal to be directly observed on the defined surface or in the defined region. When the modulating means is in the second mode, this allows the effect produced by any light from the second source incident on the defined surface or in the defined region to be reduced.

Abstract: A scanned 2- or 3-D modulated light pattern originating from a light source and represented by a matrix of pixels is projected onto a defined surface or into a defined region distant from the light source. A plurality of means for modulating light one operated between at least a first mode and a second mode. This operation is synchronized with the scanning of the matrix of pixels so that:(a) respective modulating means is in the first mode when its associated plurality of pixels are being scanned; and (b) a respective plurality of pixels are not being scanned when its associated modulating means is in the second mode. When a modulating means is in the first mode, it allows light to be distributed from the defined surface or the defined region. When a modulating means is in the second mode, it allows the effect produced by any light incident on the desired surface or in the defined region to be reduced.

Abstract: In a discharge arc lamp, an arc tube comprises an arc tube body and a main electrode at each end inside of the arc tube body, between which in the operating condition of the lamp a discharge takes place. At each end of the arc tube is an end closure comprising an end plug joined to respective each end and a cap member, the end plug and the cap member having facing surfaces. A seal provided by sealing means to seal the cap member to the end plug includes an annular seal portion between the facing surfaces of the end plug and the cap member. One or both of the facing surfaces is so shaped that the annular seal portion has a predetermined and uniform thickness t.

Abstract: A heating unit includes a heatable surface. At least a region of the heatable surface is coated or otherwise provided with a layer incorporating a thermochromic material in sufficient quantity to influence the perceived color of the layer. The thermochromic material exhibits an absorption edge wavelength which changes reversibly with temperature in the range of from 20.degree. C. to at least 400.degree. C. The absorption edge wavelength is at least 540 nm at 20.degree. C. and progressively increases to at most 700 nm at 400.degree. C. Such a heating unit is able to provide a visual indication of whether or not the heatable surface is still hot once the power has been switched off. Useful thermochromic materials include Cd(S.sub.1-x Se.sub.x) and (Zn.sub.1-y Mn.sub.y)O.

Abstract: Langmuir Blodgett films are provided having second order molecular hyperpolarizability of at least 30.10.sup.-50 C.sup.3 m.sup.3 J.sup.-2. combined with chemical stability and a melting point of over 70.degree..They also have desirable pyroelectric properties shown by a static pyroelectric coefficient of at least 0.0039 nCcm.sup.2 k.sup.-1. The films comprise compounds of the following formula: ##STR1## wherein M is ruthenium, iron or cobalt; R.sup.1 is cyclopentadienyl, methylcyclopentadienyl, pentamethylcyclopentadienyl or indenyl;A.sup.1 is (R.sup.2).sub.3 Z or carbonyl;Q.sup.2 is (R.sup.2).sub.3 Z or carbonyl;Z is phosphorus or arsenic;R.sup.2 is an aryl of alkyl radical;A is ##STR2## Y is a straight chain alkyl or alkoxy radical comprising from 3 to 17 carbon atoms, or, when A is ##STR3## N(R.sup.3).sub.2 ; R.sup.3 is a lower alkyl radical comprising up to 5 carbon atoms; andX is PF.sub.6 or BF.sub.4.

Abstract: An electroluminescent device comprises a film containing a phosphor. Means for causing movement of electrons in the film comprising a first layer on one side of the film and a second layer on the other side of the film are provided. The film includes a first material which is also present in the first layer. It has been noted that such a device has enhanced luminescence as compared to a conventional electroluminescent device.

Abstract: An optical image rotator assembly has both a rotational axis and an optical axis. Provision is made for adjusting the alignment of the optical axis, both angularly and translationally, in relation to the rotational axis.

Abstract: An electrical connector for making a connection to a thick film track comprises a plurality of conductive fibres braided together, each of the fibres having a diameter so as to provide sufficient stiffness to the connector and to permit adhesion of the connector to a thick film track.

Abstract: A liquid crystal display cell comprises first and second substrates located in a substantially parallel relative arrangement to define an active display region therebetween when filled with liquid crystal material. The cell further includes means to effect filling of the active display region with liquid crystal material from at least a part of an edge of the active display rgion.

Abstract: An adapter for mounting a lamp fitting on a lighting track comprises a hollow body member, a head which can be slid along the track and a pair of resilient contact strips. An electrically insulating separator maintains the contact strips in spaced apart relationship in the body member and respective pairs of grooves formed in the head hold the contact strips so that bowed sections of the contact strips press against supply rails which extend along the side walls of the track.

Abstract: A method is provided for manufacturing a cold cathode field emission device. The method comprises the steps of:providing a layer of anodised alumina having a plurality of elongate pores which are substantially orthogonal to major surfaces of the layer;filling said pores completely with an electron emission material, and then removing at least a part of said layer to form a defined surface of said layer and to produce a plurality of electron emissive spikes extruding from and at an angle to said defined surface wherein a plurality of electron emissive structures are produced, each structure comprising a plurality of electron emissive spikes inclined to one another.

Abstract: A display device includes equipment for projecting light onto a surface. The equipment includes a beam-splitter for effecting partial reflection and partial transmittance of an incident beam. On one side of the beam-splitter are a light source for directing light onto the beam-splitter and a mirror for directing back towards the beam-splitter light reflected therefrom. On the other side of the beam-splitter is a louvre for permitting passage therethrough of light of incident angle relative to a normal to the beam-splitter with in a predetermined restricted range.

Abstract: A microengineered pressure actuated switch includes a domed diaphragm having a snap-action response between defined states (d.sub.1, d.sub.5) of the diaphragm. This response is to an applied pressure differential across the diaphragm. The diaphragm is supported on a substrate of semiconductor material. In a method of making such a switch, a layer of inorganic material is provided on one side of a substrate of semiconductor material. Semiconductor material is removed from the substrate such that a defined region of the layer is not in contact with the semiconductor material, this defined region forming the diaphragm. The layer of inorganic material is so stressed that after semiconductor material is removed, the layer assumes a domed configuration and incorporates a pre-bias in the direction of doming.

Abstract: A tag for use with an electromagnetic identification system includes a magnetic control component 1, having alternating regions 10, 20 of, respectively, high and medium coercivity material, and an element 30 of magnetically soft material. The element 30 may be polarized so as to deactivate the tag by, for example, selectively demagnetizing the regions 20 of medium coercivity, such as by exposing the tag to an alternating magnetic field having an initial field strength which is intermediate between the coercivity of the regions 10, 20, which may be formed as a striped coating or from a number of discrete magnetic components.

Abstract: An optical rotator such as a Pechan rotator is arranged to rotate an image about a given axis. Light entering an input surface of the rotator is subjected to a number (e.g. five) of reflections, alternate reflections being total internal reflections and the intervening ones being mirror reflections. At least one of the surfaces, preferably one at which total internal reflection occurs, bears a layered polarizing material arranged to impart a defined polarization effect as between light entering and exiting the rotator.

Abstract: A pyroelectric film has a pattern of inter-connected electrodes formed on one major surface, and a pattern of discrete electrodes formed on the other major surface. Each discrete electrode has an aperature in which is formed a respective electrically conductive pad. The film is supported by pillars connected to the pads, the pillars also providing a path for electrical signals between the pads and a signal processing means. Each discrete electrode is connected to a respective pad by a respective strip of electrically conductive material.

Abstract: The holographic manufacture of Compact Discs has three stages namely mastering, production of the sub-master holograms and replication. In the production stage, a holographic plate, spacer and master transparency are positioned against a prism, and then illuminated with split beams from a laser in order to record a hologram, at the plate, of the master transparency. The resultant hologram of the plate is then mass replicated on polycarbonate or photochromic discs to produce compact Discs compatible to conventional Compact Disc players.

Abstract: A tag 2 for use in an electronic article surveillance system comprises a magnetically structured component 4 in close proximity to a striplike element 6 of magnetically soft material. The component 4 includes magnetic particles 8 orientated into particular directions in regions 10, 12, preferably at .+-.45.degree. relative to the longitudinal axis of the tag.The tag 2 can be deactivated by longitudinal wiping with a deactivator providing a magnetic field corresponding to the angle of orientation of the particles 8. Deactivation is, therefore, straightforward for a check out operator but not for a potential thief.The orientated particles 8 can be used to define an interpretable code enabling product inventory with deactivation.

Abstract: A gas sensitive device, for example a gas sensitive MISFET (FIGS. 1 to 3) has a gas-sensitive electrode (15) comprising a catalytically active metal (e.g. Pt or Pd) and a non-metallic material (e.g. SiO.sub.2) mixed with, or deposited at an exposed surface of, the metal to modify the catalytic activity of the metal. The electrode has an enhanced sensitivity to, and selectivity of, certain gases. The composite material is applicable to other gas-sensitive devices, e.g. an optical fibre gas sensor.