Patents Assigned to EMI Limited
  • Image forming apparatus
    Patent number: 4255658
    Abstract: The imager comprises an array 4 of detectors, and an array 6 of LEDs each detector being connected to a corresponding LED by a respective signal processing channel 5a. Common to all the channels is a ramp generator 12. Each channel has a comparator 9 which compares the ramp with the signal from its detector to produce a pulse width modulated signal for its LED. Thus the LED is always driven at the same point on its characteristic, variation of brightness being achieved by variation of pulse width. Use of a common ramp generator makes for simple change of ramp shape, temperature window, offset and .gamma. law by simply changing only the ramp generator.
    Type: Grant
    Filed: February 5, 1979
    Date of Patent: March 10, 1981
    Assignee: EMI Limited
    Inventor: Ivan R. Hurst
  • Medical radiographic apparatus and method
    Patent number: 4250387
    Abstract: Computerized tomographic X-ray apparatuses direct X-rays, usually in a fan-shaped distribution, through the body of a patient. In some examples the fan distribution may subtend angles of 50.degree. or more at the source. It has been found that such tubes, particularly of the rotating anode type, tend to have X-ray emission from regions surrounding the focal spot and it is not convenient to use anode shields to eliminate it. This off-focus radiation can present problems, especially when attenuators are used to equalize absorbing paths through the patient, since the off-focus radiation can sometimes be less attenuated than the main beam. It is proposed to correct the signals produced by the X-ray detectors, for off-focus radiation. A profile of off-focus or halo radiation is produced and the attenuation imposed on it is estimated.
    Type: Grant
    Filed: October 12, 1979
    Date of Patent: February 10, 1981
    Assignee: EMI Limited
    Inventors: Godfrey N. Hounsfield, Richard M. Waltham, Daniel J. Pisano, Jr., Erlvada A. Olson
  • Mercury-metal halide discharge lamp
    Patent number: 4247798
    Abstract: Metal halide discharge lamps based on sodium and scandium iodides show improved color rendering without important loss of efficacy by the inclusion of lithium iodide, especially in the molar proportion of 10-50% LiI based on the total of Li, Na and Sc iodides. The ratio of alkali metal of SC iodides should be between 5.4:1 and 57.5:1. Especially preferred are lamps with less than 10 molar % ScI and the lamps may additionally contain caesium iodide to broaden the emission spectrum.
    Type: Grant
    Filed: April 3, 1979
    Date of Patent: January 27, 1981
    Assignee: Thorn Emi Limited
    Inventors: Stephen H. Howe, Barry Preston, Robert B. Page
  • Medical radiographic apparatus
    Patent number: 4246484
    Abstract: In a computer-assisted tomography (CAT) apparatus, in which a fan-shaped X-ray distribution is rotated about the patients body, it is possible to use a ring of stationary detectors disposed to receive the radiation after passage through the body. In this arrangement the ring of detectors is of smaller radius than the locus of motion of the radiation source. It would appear that this would cause the detectors to obscure the body from the radiation. An arrangement disclosed moves out of the radiation beam those detectors which would present an obstruction so that only those required to collect radiation lie in the beam.
    Type: Grant
    Filed: January 8, 1979
    Date of Patent: January 20, 1981
    Assignee: EMI Limited
    Inventor: Richard W. Fetter
  • Radiography
    Patent number: 4233662
    Abstract: A medical diagnostic X-ray machine (CT scanner) is disclosed using a technique of filtered or compensated back-projection or layergram to form a picture of a patient slice. In examining a body by means of X-rays or other penetrating radiation, signals are derived representing the logarithm of the absorption of individual beams in sets of parallel beams which are passed through the body in a single plane at many different angles. Corresponding to each such signal there is derived a summation signal produced by a process of convolution using a convolution function of a special form which is such that the convolution can be effected in a recirculatory circuit. An image of the plane section is reconstructed by selectively superimposing the summation signals producing the effect of what may be termed a compensated layergram.
    Type: Grant
    Filed: February 13, 1978
    Date of Patent: November 11, 1980
    Assignee: EMI Limited
    Inventor: Christopher A. G. LeMay
  • Ultrasonic transducers
    Patent number: 4228687
    Abstract: In a rotating probe ultrasonic system the effective PRF may not be sufficiently high for certain purposes, such as examination of the foetal heart. The invention combines fixed transducers looking at a limited region with a rotating probe scanning over a larger region to give a higher effective PRF in the limited region. The two displays are preferably separate although the display of the larger region may conveniently indicate the location of the limited region.
    Type: Grant
    Filed: March 23, 1979
    Date of Patent: October 21, 1980
    Assignee: EMI Limited
    Inventor: Brian W. Fraser
  • Radiography
    Patent number: 4223384
    Abstract: In a computerised tomographic (CAT) X-ray apparatus passage of the radiation through high absorption (bone) regions can change a characteristic of the radiation, such as its frequency spectrum. This can introduce error into the final representation. Correction is provided by computing a first representation, identifying areas of bone and then determining corrections for those areas which can be used to provide a subsequent move accurate representation. Errors caused by scattering can also be compensated in this way.
    Type: Grant
    Filed: June 29, 1977
    Date of Patent: September 16, 1980
    Assignee: EMI Limited
    Inventors: Godfrey N. Hounsfield, MacArthur J. Gollifer
  • Rotary drive systems
    Patent number: 4197755
    Abstract: In radiographic apparatus of the kind known as computerized tomographic (CT) apparatus, a source of radiation is moved around a patient to irradiate the patients body from a plurality of directions. In certain types of CT apparatus the motion includes a stepped rotation. During each rotational step reaction forces are transferred to the fixed part of the apparatus and for rapid movements the reaction forces can become excessive. To reduce the reaction forces a compensating means is provided to oppose the reaction forces. This may be a resilient member such as a spring and may react against a member, such as a cam, which is shaped to adjust the compensating force to a suitable value.
    Type: Grant
    Filed: December 1, 1977
    Date of Patent: April 15, 1980
    Assignee: EMI Limited
    Inventor: Anthony M. Williams
  • Magnetic recording
    Patent number: 4197989
    Abstract: Magnetic recording media including permanent structures of aligned acicular particles have been proposed as a means of identifying and authenticating a medium. A structure which has an improved remanence difference signal is described. A method of making and examining such a structure is described. Arrangements of such media and record/read-out apparatus by which information can be recorded and read-out without interference from the structural remanence differences are described. The use of the media for security documents such as credit cards is described.
    Type: Grant
    Filed: June 26, 1978
    Date of Patent: April 15, 1980
    Assignee: EMI Limited
    Inventor: Ralph R. Pearce
  • Apparatus for examining a body by radiation such as X or gamma radiation
    Patent number: 4188541
    Abstract: A medical diagnostic X-ray machine is described in which X-ray measurements are taken of the attenuation suffered by X-radiation when projected across a cross-sectional slice of a patient's body along each of many substantially linear beam paths and are subjected to compensated back-projective processing to produce an X-ray picture representing the variation of attenuation of the radiation with position over the slice. Neighboring beam paths are arranged to overlap each other.
    Type: Grant
    Filed: December 8, 1977
    Date of Patent: February 12, 1980
    Assignee: EMI Limited
    Inventor: Godfrey N. Hounsfield
  • Security document
    Patent number: 4186944
    Abstract: A method of printing wherein magnetic particles dispersed in an ink are selectively orientated prior to printing onto a document where the particles are aligned on a carrier while the ink is in a low viscous state and the printing is effected when the ink is in a high viscous state. The method by which the viscosity is changed is the selective application of heat.
    Type: Grant
    Filed: April 28, 1978
    Date of Patent: February 5, 1980
    Assignee: EMI Limited
    Inventor: Ralph R. Pearce
  • Electrical power supplies
    Patent number: 4186329
    Abstract: An electrical power supply for an X-ray tube has a source capable of providing constant current at a desired potential to a capacitor means which supplies pulses of current in excess of the source current to the X-ray tube. As each pulse is supplied, the potential at the output of the supply tends to drop. One side of the capacitor means is connected to the output. A compensator is connected to the other side of the capacitor means and responds to a drop in the output potential to apply to the other side of the capacitor means a voltage which maintains the output voltage constant.
    Type: Grant
    Filed: April 27, 1978
    Date of Patent: January 29, 1980
    Assignee: EMI Limited
    Inventor: Ian A. Fairbairn
  • Construction of collimators and/or detectors for penetrating radiation
    Patent number: 4185195
    Abstract: A method of constructing arrays of collimators and/or detectors for penetrating radiation is described. A tape or foil is wound alternatively over and under rods provided in upper and lower sets to define a plurality of substantially parallel or slightly inclined channels for the radiation. The channels can be filled with suitable plastics material.
    Type: Grant
    Filed: December 30, 1977
    Date of Patent: January 22, 1980
    Assignee: EMI Limited
    Inventor: John F. Moore
  • Arrangements for detectors of radiation
    Patent number: 4181856
    Abstract: An ionizing radiation detector arrangement includes scintillator crystals and respective photodiodes of elongate form and mountings to assemble these in sub-arrays of, for example, four, units. The mountings are shaped to permit assembly around a ring with radially extending cards bearing circuit components. Assembly is made accurately by including skewed lugs in the mountings.
    Type: Grant
    Filed: February 27, 1978
    Date of Patent: January 1, 1980
    Assignee: EMI Limited
    Inventor: Phillip R. Bone
  • Data transmission in radiographic apparatus
    Patent number: 4181850
    Abstract: In radiographic apparatus in which a source of radiation and detectors receiving the radiation are orbited about a position for locating a patient, the examination can be carried out using a rotation through 360.degree. or more. This arrangement uses slip rings for carrying data, including the output of the detectors and provides a slip ring arrangement suitable for high speed use. The slip rings can have capacitative coupling to avoid data loss if the brushes are allowed to bounce and for use therewith the data should be encoded in a D.C.-component-removing digital code.
    Type: Grant
    Filed: September 14, 1978
    Date of Patent: January 1, 1980
    Assignee: EMI Limited
    Inventor: Ian A. Fairbairn
  • Adjustable compensating device for radiographic apparatus
    Patent number: 4181858
    Abstract: In computerized tomography (CT) apparatus it is usual to rotate a source of radiation about a body which, with associated support, is approximately circular in cross-section. Compensation, for unequal radiation paths through such a circular cross-section body, can be compensated by suitably shaped attenuating masses. This invention provides such masses which are relatively movable, in response to an optical detector system, to adjust for different body sizes. Each mass extends right across the radiation spread so that no discontinuities a rise for particular relative positions of the two masses.
    Type: Grant
    Filed: December 30, 1977
    Date of Patent: January 1, 1980
    Assignee: EMI Limited
    Inventor: John F. Moore
  • Radiography
    Patent number: 4172978
    Abstract: In a computerized tomographic apparatus, different detectors are caused to receive radiation along substantially the same beam path through the body in order to permit the evaluation of differences in performance of the detectors. This evaluation is average with other evaluations made in respect of the same detector for other beam paths so as to reduce the risk that erroneous performance differences may be evaluated in the event that any of the relevant beam paths lies adjacent a bone edge in a patient's body. Also disclosed are techniques for electronically deflecting the radiation so that part at least of the radiation is taken clear of the body and can be detected to provide reference signals.
    Type: Grant
    Filed: August 11, 1977
    Date of Patent: October 30, 1979
    Assignee: EMI Limited
    Inventors: Godfrey N. Hounsfield, Colin C. Oliver, Stephen R. Bates, Brian H. Lill
  • Radiography
    Patent number: 4171476
    Abstract: In a computerized tomographic apparatus in which the source and detectors are moved angularly around the body, the angular movement of the source is, in effect, periodically arrested so that the detectors, which are of greater angular extent than the distribution of radiation produced by the source, slide through the distribution. In this way successive detectors can be made to view the same beam in the distribution.
    Type: Grant
    Filed: February 21, 1978
    Date of Patent: October 16, 1979
    Assignee: EMI Limited
    Inventor: Richard M. Waltham
  • Correlation techniques
    Patent number: 4164728
    Abstract: In a correlation system, such as may be used in an autolock follow arrangement, the correlation is effected on the basis of line integrals of data relating to pictures of substantially the same scene obtained at different times. The formation of line integrals allows a straightforward, linear processing technique to be used for the correlation.
    Type: Grant
    Filed: December 9, 1977
    Date of Patent: August 14, 1979
    Assignee: EMI Limited
    Inventor: Robin G. Marsh
  • Cable storage assembly for scanning apparatus
    Patent number: 4163526
    Abstract: In computerized tomographic apparatus, in which a radiation source orbits through several revolutions about a patient, handling of cables can present a problem. This invention provides an arrangement for cable handling in which two cable stores have relative rotation. The cable is transferred, during rotation, from one to the other by a transfer means which also moves around the rotation axis.
    Type: Grant
    Filed: August 23, 1977
    Date of Patent: August 7, 1979
    Assignee: EMI Limited
    Inventor: Anthony M. Williams