Patents Assigned to Thorn Electrical Industries Limited
  • Patent number: 4366411
    Abstract: A quartz iodine studio lamp has a tungsten filament (32) formed of several sections (34) arranged in a plane between two quartz bridges (16,18) which are in turn supported by support wires (20,22). One end of the filament assembly (14) is supported in a seal (28) forming one end of the envelope (12). To stabilize the filament assembly, so as to stop it hitting the envelope wall, two spring coils (40) are carried by the bridge (16) remote from the seal (28) and extend transversely of the envelope to its inner surface.
    Type: Grant
    Filed: June 3, 1980
    Date of Patent: December 28, 1982
    Assignee: Thorn Electrical Industries Limited
    Inventor: Kenneth B. Robinson
  • Patent number: 4316936
    Abstract: The invention provides a particulate sealing material for use in preparing hermetic seals between ceramic and cermet members, which material comprises at least 70 wt. % refractory oxide and minor quantities of non-vitreous additive comprising SiO.sub.2, MgO and B.sub.2 O.sub.3. This particulate sealing material is conveniently pressed into the form of a coherent element shaped to suit the particular sealing operation concerned, e.g. the sealing of an open end of a ceramic arc tube to a cermet closure therefor. The invention also provides a method of sealing a ceramic component to a cermet member by interposing said sealing material between the opposed faces of the component and member and applying heat and pressure to sinter the sealing material and achieve a seal between the component and member.
    Type: Grant
    Filed: September 4, 1979
    Date of Patent: February 23, 1982
    Assignee: Thorn Electrical Industries Limited
    Inventor: Peter Hing
  • Patent number: 4305637
    Abstract: In a lamp such as a GLS incandescent filament lamp the cap comprises a metal shell and an electrically insulating base, the base being formed in two parts preferably moulded of synthetic resin and formed to interfit with one another, of which the first part has passages for the lead-in wires from the lamp envelope such that the free ends of the wires lie between the first and second parts and the second part carries one or more electrical contact members to engage the lead-in wires and form the terminal(s) of the lamp.
    Type: Grant
    Filed: May 17, 1979
    Date of Patent: December 15, 1981
    Assignee: Thorn Electrical Industries Limited
    Inventors: Ben Grewcock, Arthur S. Vause, Frank Woodward
  • Patent number: 4278908
    Abstract: In a method of dosing a gas discharge lamp by opening a dosing capsule by the heating action of an electromagnetic field on a metallic support, the support is in the form of a sheet metal clip embracing the capsule and having an opening through which the softened glass of the capsule is forced by the internal pressure. Breakage of the capsule is eliminated and the glass forced through the opening ensures retention of the capsule by the clip. The clip is preferably of ferromagnetic material.
    Type: Grant
    Filed: March 21, 1979
    Date of Patent: July 14, 1981
    Assignee: Thorn Electrical Industries Limited
    Inventor: Basil Antonis
  • Patent number: 4204137
    Abstract: The invention relates to electrode mount assemblies for electric discharge and fluorescent lamps. In accordance with the first aspect of the invention the portions of the electrode support wires which are exposed to electron bombardment within the body of the lamp have at least their surface formed of refractory material. The exposed portions may be coated with a refractory material such as boron nitride or made wholly of a refractory metal such as molybdenum. According to a second aspect of the invention relatively cheap soda-lime silicate glass can be used for the end flares of the lamp tubes, because the provision of refractory surfaces on the vulnerable portions of the support wires enables a metal to be chosen for the portions of the wires passing through the glass seal which closely matches the glass in thermal expansion coefficient.
    Type: Grant
    Filed: July 18, 1977
    Date of Patent: May 20, 1980
    Assignee: Thorn Electrical Industries Limited
    Inventor: Ashutosh Roy
  • Patent number: 4185922
    Abstract: The invention relates to the manufacture of electric lamps containing fluorine in their gas fill. Fluorine can be accurately and conveniently introduced into an electric lamp envelope in the form of a fluorocarbon polymer. If a soluble fluorocarbon polymer, such as a degraded PTFE, is dissolved in a suitable solvent, for example a fluorine-substituted hydrocarbon or halocarbon solvent, the resulting solution can be metered with great accuracy into the lamp envelope and the solvent subsequently evaporated. The invention avoids the difficulties otherwise inherent in dispensing accurate quantities of an extremely reactive gaseous material.
    Type: Grant
    Filed: February 23, 1978
    Date of Patent: January 29, 1980
    Assignees: Thorn Electrical Industries Limited, Imperial Chemical Industries Limited
    Inventors: John M. Rees, Christopher A. Horler, Anthony P. Downing
  • Patent number: 4165475
    Abstract: A starter circuit for a hot cathode discharge lamp which has a switching element which is connected across the lamp to permit a cathode heating current to flow and then opens to permit the lamp to strike. The starter circuit has a thyristor as the switch element, and a control circuit for rendering the thyristor conductive at a desired point during each cycle of the applied voltage. The control circuit includes means for increasing the instantaneous applied voltage which is required to trigger the thyristor with successive cycles of the applied voltage after switch-on of the circuit. This means preferably includes a capacitor which is progressively charged to provide an increasing bias which must be overcome by the applied voltage. If the lamp fails to strike, the required voltage for triggering goes on increasing until it is too high for the thyristor to trigger at all. No damage can then occur to the starter circuit or the lamp ballast.
    Type: Grant
    Filed: April 17, 1978
    Date of Patent: August 21, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventors: John C. Pegg, Clive R. Walker
  • Patent number: 4156889
    Abstract: An improved electric mirror lamp comprising a concave mirror on the focus of which a light source, for example an incandescent filament is fixed, and the lamp also includes locating means by which its position in a lamp holder is determined and support means holding the mirror at a fixed position relative to the locating means. A support mirror is an integral moulded body having portions adapted to position the locating of the mirror. The locating means may be constituted by a locating ring secured to an end cap and the support means may include indentations which engage and retain the end cap. The electric light source or bulb may be replaceable and the mirror may be formed directly on an appropriate concave surface of the support means.
    Type: Grant
    Filed: September 13, 1977
    Date of Patent: May 29, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventors: Alex L. Halberstadt, John C. Maddocks
  • Patent number: 4155757
    Abstract: Conducting cermets with volume fractions of nickel down to 0.045 are produced by coating relatively coarse refractory oxide granules with fine metal powder particles are compacting and sintering the coated granules. Using oxide granules in the size range 400 to 800 microns it is possible to make conducting cermets having the same volume fraction of metal and thus the same thermal expansion coefficients as insulating cermets prepared from finer granules of the same oxide. The cermets can be used to fabricate tubes and components for electric lamps and may include integrally formed conducting and insulating regions.
    Type: Grant
    Filed: December 8, 1976
    Date of Patent: May 22, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventor: Peter Hing
  • Patent number: 4155758
    Abstract: Conducting cermets with volume fractions of nickel down to 0.045 are produced by coating relatively coarse refractory oxide granules with fine metal powder particles and compacting and sintering the coated granules. Using oxide granules in the size range 400 to 800 microns it is possible to make conducting cermets having the same volume fraction of metal and thus the same thermal expansion coefficients as insulating cermets prepared from finer granules of the same oxide. The cermets can be used to fabricate tubes and components for electric lamps and may include integrally formed conducting and insulating regions.
    Type: Grant
    Filed: December 8, 1976
    Date of Patent: May 22, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventors: David T. Evans, Peter Hing, Raymond Marshall
  • Patent number: 4155061
    Abstract: An inductor such as a fluorescent lamp choke comprises a bobbin carrying a winding, a laminated core, and a sheet metal casing consisting of two parts which have interengaging flanges and grooves along four parallel edges which are slid together and subsequently bent over and pressed against end faces of the core to secure the parts of the casing together so that they exert pressure on the core from all sides.
    Type: Grant
    Filed: November 23, 1977
    Date of Patent: May 15, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventors: Tony C. Cook, Robert H. Rhodes
  • Patent number: 4145332
    Abstract: A lamp capping cement for electric lamps comprises a resin component consisting essentially of a condensation product of an aralkyl ether and a phenol mixed with a cross-linkable polymer or resin, a heat-resistant filler component, and a liquid diluent. The preferred cross-linkable polymer is a carboxylated acrylic polymer which may constitute 1 to 15% of the cement. This cement is capable of withstanding higher operating temperatures in incandescent filament lamps without breakdown.
    Type: Grant
    Filed: September 20, 1976
    Date of Patent: March 20, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventor: George E. Coxon
  • Patent number: 4135110
    Abstract: Electrical discharge lamps containing mixed halides of superior performance are provided by the inclusion in the lamp of a volatile complex halide compound of tin and sodium. The halide may be added as a mixture of tin and sodium halide but the complex is formed in operation of the lamp and has a much higher volatility than the constituent halides. The preferred lamps contain 5 to 100 micromoles tin and 1 to 250 micromoles sodium halide per cubic centimeter, in a gas fill containing more than 50 micromoles per c.c. mercury.
    Type: Grant
    Filed: September 8, 1977
    Date of Patent: January 16, 1979
    Assignee: Thorn Electrical Industries Limited
    Inventors: Alan G. Chalmers, Frank L. Whittaker, David O. Wharmby
  • Patent number: 4105931
    Abstract: An inductor structure for use in a discharge lamp circuit has wound around at least part of its magnetic core first and second conducting foils. The first conducting foil is insulated from the magnetic core. The second conducting foil is interwound with but separated and insulated from the first conducting foil by a first dielectric foil and a second dielectric foil interwound with the conducting foils. The conducting foils have different numbers of turns. The conducting foil with the greater number of turns has all its turns except its excess turns wound oppositely to the turns of the other conducting foil. The structure provides a lower level of harmonic content above main frequency in the lamp and mains current waveforms.
    Type: Grant
    Filed: September 27, 1976
    Date of Patent: August 8, 1978
    Assignee: Thorn Electrical Industries Limited
    Inventors: Eric H. Pritchard, Thomas R. Passmore
  • Patent number: 4100594
    Abstract: In a beam-projecting lamp such as a vehicle headlamp or theatre spotlight which has a mask to delimit the edge of the beam, color fringing due to the mask is reduced by the use of a mask having separate front and rear edges or by splitting the projection lens into upper and lower halves, the arrangement in each case producing both a virtual erect mask image from one half of the projection lens and a real inverted mask image from the other half.
    Type: Grant
    Filed: August 23, 1976
    Date of Patent: July 11, 1978
    Assignee: Thorn Electrical Industries Limited
    Inventor: Allan Victor Stewart Gould
  • Patent number: 4099081
    Abstract: The invention relates to the production of metal halide discharge lamps. Residual water vapor within the envelope of metal halide discharge lamps is gettered by the inclusion of a small quantity of phosphorus. By this means it is possible to dispense with complexities in the conventional manufacture of such discharge lamps arising from the hygroscopic nature of many metal halides.
    Type: Grant
    Filed: February 24, 1977
    Date of Patent: July 4, 1978
    Assignee: Thorn Electrical Industries Limited
    Inventor: Thomas Somner Ainsworth
  • Patent number: 4096088
    Abstract: Phosphors having useful flourescent emission properties comprise aluminates of magnesium, zinc and/or lithium having an hexagonal or so-called ".beta.-alumina" crystal structure and activated by cerium and terbium. In preferred phosphors the ratio of Mg:Al is from 0.01 to 0.5:1, Ce:Al from 0.001 to 0.1:1 and Tb:Al from 0.005:1 to 0.25:1. Where zinc or lithium wholly or partially replace the magnesium, chemically equivalent amounts may be used. A particuarly useful phosphor conforms substantially to the approximate formula (Ce,Tb).sub.1 Mg.sub.1-2 Al.sub.22 O.sub.x, where x is the number of atoms of oxygen required to satisfy the valencies of the metals. The invention also provides a valuable process for the preparation of such aluminate phosphors, giving a product of fine grain which may not require milling or other severe grinding (which is expensive and tends to harm emission properties) to bring it into the preferred particle size range for lamp manufacture.
    Type: Grant
    Filed: February 7, 1977
    Date of Patent: June 20, 1978
    Assignee: Thorn Electrical Industries Limited
    Inventors: Peter Whitten Ranby, Doreen Yvonne Hobbs
  • Patent number: 4090101
    Abstract: The invention relates to the manufacture of electric lamps containing fluorine in their gas fill. Fluorine can be accurately and conveniently introduced into an electric lamp envelope in the form of a fluorocarbon polymer. If a soluble fluorocarbon polymer, such as a degraded PTFE, is dissolved in a suitable solvent, for example a fluorine-substituted hydrocarbon or halocarbon solvent, the resulting solution can be metered with great accuracy into the lamp envelope and the solvent subsequently evaporated. The invention avoids the difficulties otherwise inherent in dispensing accurate quantities of an extremely reactive gaseous material.
    Type: Grant
    Filed: January 17, 1977
    Date of Patent: May 16, 1978
    Assignees: Thorn Electrical Industries Limited, Imperial Chemical Industries Limited
    Inventors: John Michael Rees, Christopher Arthur Horler, Anthony Peter Downing
  • Patent number: 4026816
    Abstract: Phosphors having useful fluorescent emission properties comprise aluminates of magnesium, zinc and/or lithium having an hexagonal or so-called ".beta.-alumina" crystal structure and activated by cerium and terbium. In preferred phosphors the ratio of Mg:Al is from 0.01 to 0.5:1, Ce:Al from 0.001 to 0.1:1 and Tb:Al from 0.005:1 to 0.25:1. Where zinc or lithium wholly or partially replace the magnesium, chemically equivalent amounts may be used. A particularly useful phosphor conforms substantially to the approximate formula (Ce,Tb).sub.1 Mg.sub.1.sub.-2 Al.sub.22 O.sub.x, where x is the number of atoms of oxygen required to satisfy the valencies of the metals. The invention also provides a valuable process for the preparation of such aluminate phosphors, giving a product of fine grain which may not require milling or other severe grinding (which is expensive and tends to harm emission properties) to bring it into the preferred particle size range for lamp manufacture.
    Type: Grant
    Filed: January 17, 1975
    Date of Patent: May 31, 1977
    Assignee: Thorn Electrical Industries Limited
    Inventors: Peter Whitten Ranby, Doreen Yvonne Hobbs
  • Patent number: 4027189
    Abstract: A linear tungsten halogen lamp which can be burnt at any desired angle is made by selecting the gas filling and the halogen or halogen-containing compound to satisfy certain conditions which can be mathematically expressed. If these conditions are satisfied, the separation of halogen which occurs in conventional linear tungsten halogen lamps when burnt at angles inclined to the horizontal is reduced to an acceptable level. It is found that the maximum degree of separation of the halogen, herein denoted by .gamma. max, can be calculated from lamp parameters as a function of the thermal diffusion coefficient of the halogen in the filling, the tube length, the temperature difference between the filament and the tube wall, the average gas temperature, the radius of the coiled filament and the inside radius of the tube.
    Type: Grant
    Filed: September 3, 1975
    Date of Patent: May 31, 1977
    Assignee: Thorn Electrical Industries Limited
    Inventor: James Richard Coaton