Patents by Inventor Hendrik J. de Wit

Hendrik J. de Wit has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5932819
    Abstract: The invention relates to a deflection ring of sintered MgZn-ferrite material. In accordance with the invention, this deflection ring is characterized in that the majority of the grains of the sintered material have a monodomain structure. By virtue thereof, a relatively small heat dissipation occurs in the ring when it is used in a cathode ray tube. The average grain size of the sintered MgZn-ferrite material is preferably 2.8 micrometers or less. MgZn-ferrite materials whose composition corresponds to the formula Mg.sub.1-z Zn.sub.z Fe.sub.2-y O.sub.4, wherein 0.1<z<0.4 and 0.01<y<0.3, have the additional advantage that they have a relatively high saturation magnetization and a relatively high electrical resistance. The invention also relates to a cathode ray tube comprising the above-mentioned deflection ring and to a mo1lding made from the above-mentioned MgZn-ferrite material.
    Type: Grant
    Filed: March 4, 1998
    Date of Patent: August 3, 1999
    Assignee: U.S. Philips Corporation
    Inventors: Pieter J. Van Der Zaag, Pieter J. Van Der Valk, Hendrik J. De Wit
  • Patent number: 5912529
    Abstract: A display device comprising a display tube having a display screen with a pattern of phosphor elements. To reduce mislandings of electron beams, the display tube is accommodated within an external magnetic shield which is formed by one or more individual frames composed of bars of a magnetizable material and one or more excitable coils. The coils may be arranged, for example, alongside the frames.
    Type: Grant
    Filed: April 9, 1997
    Date of Patent: June 15, 1999
    Assignee: U.S. Philips Corporation
    Inventors: Hendrik J. De Wit, deceased, Henricus J. Kunnen, legal representative
  • Patent number: 5841225
    Abstract: Deflection ring of sintered MgZn-ferrite material, cathode ray tube comprising such a ring and moulding made from this material.The invention relates to a deflection ring of sintered MgZn-ferrite material. In accordance with the invention, this deflection ring is characterized in that the majority of the grains of the sintered material have a monodomain structure. By virtue thereof, a relatively small heat dissipation occurs in the ring when it is used in a cathode ray tube. The average grain size of the sintered MgZn-ferrite material is preferably 2.8 micrometers or less. MgZn-ferrite materials whose composition corresponds to the formula Mg.sub.1-z Zn.sub.z Fe.sub.2-y O.sub.4, wherein 0.1<z<0.4 and 0.01<y<0.3, have the additional advantage that they have a relatively high saturation magnetization and a relatively high electrical resistance.
    Type: Grant
    Filed: November 7, 1995
    Date of Patent: November 24, 1998
    Assignee: U.S. Philips Corporation
    Inventors: Pieter J. Van Der Zaag, Pieter J. Van Der Valk, Hendrik J. De Wit
  • Patent number: 5644191
    Abstract: Color display tube having a display screen with a pattern of phosphor elements. To reduce mislanding errors of the electron beams, particularly in the y-direction, the color display tube is arranged within an external magnetic shield which is constituted by an open arrangement (frame) of bars of a soft-magnetic material. The bars jointly constitute, for example the ribs of a block.
    Type: Grant
    Filed: October 28, 1994
    Date of Patent: July 1, 1997
    Assignee: U.S. Philips Corporation
    Inventors: Hendrik J. De Wit, Willem Schouten
  • Patent number: 5559401
    Abstract: Color display tube with a shadow mask, a shield of a ferromagnetic material and a demagnetizing device having a set of demagnetizing coils. The demagnetizing device is provided with means for energizing the demagnetizing coils in two steps which are shifted in time with respect to each other, while the location of the turns of the demagnetizing coils is such that upon the passage of current through only the one coil, the magnetic field generated by the coil is capable of demagnetizing those parts of color selection electrode and screen which are not demagnetized upon the passage of current through only the other coil, and conversely.
    Type: Grant
    Filed: October 4, 1995
    Date of Patent: September 24, 1996
    Assignee: U.S. Philips Corporation
    Inventor: Hendrik J. De Wit
  • Patent number: 5434470
    Abstract: A color display tube is presented having an elongated display screen with a pattern of phosphor dots. In order to render mislanding errors of the electron beams as small as possible, particularly in the y direction, the color display tube has an internal shield which is provided proximate to its gun-sided open end with a structure for deflecting the field lines of the axial component of the earth's magnetic field more to the short sides than to the long sides of the shield. This structure is particularly constituted in that the short sides are provided with edges extending toward the gun, or in that a border strip has been removed from the long sides.
    Type: Grant
    Filed: October 19, 1994
    Date of Patent: July 18, 1995
    Assignee: U.S. Philips Corporation
    Inventors: Hendrik J. De Wit, Willem Schouten
  • Patent number: 5234775
    Abstract: The invention relates to a soft magnetic multilayer film which comprises a number of crystalline main layers and a number of amorphous secondary layers, the main layer substantially exclusively comprising iron as the magnetic constituent, and the secondary layer comprising mainly iron as the magnetic constituent. Such multilayer films exhibit a relatively low magnetostriction constant which is almost not influenced by temperature treatments. Such films are very suitable for use in magnetic heads.
    Type: Grant
    Filed: December 4, 1992
    Date of Patent: August 10, 1993
    Assignee: U.S. Philips Corporation
    Inventors: Franciscus W. A. Dirne, Hendrik J. De Wit, Cornelis H. M. Witmer, Johannes A. M. Tolboom, Peter Lasinski
  • Patent number: 4685012
    Abstract: A magnetic head having a core of a magnetizable material around a part of which a coil is provided. A transducing gap is formed between two core parts of a magnetically anisotropic, amorphous ferromagnetic metal. The core parts of a magnetically anisotropic, amorphous ferromagnetic material have a magnetic anisotropy direction induced by a thermal treatment in a magnetic field which is in the plane of the core parts and encloses an angle .alpha. with the direction in which magnetic flux traverses the core parts during operation. .alpha. preferably is equial to 90.degree.. By these means an increased permeability in the MHz range is reached in combination with a minimum loss component.
    Type: Grant
    Filed: October 30, 1985
    Date of Patent: August 4, 1987
    Assignee: U.S. Philips Corporation
    Inventors: Hendrik J. De Wit, Marcel Brouha, Ulrich E. Enz, Kornelis Jager, Albertus J. C. Van Der Borst, Gijsbertus W. Turk
  • Patent number: 4497699
    Abstract: A method of treating foil for use in electrolytic capacitors in which the foil moves in one direction through a treatment liquid and in which the capacitance is measured continuously by means of at least one current-carrying electrode from which alternating current is conveyed and at least one voltage electrode at a small distance from the foil. The foil capacitance is measured by means of a phase-sensitive voltmeter. The measured capacitance is used to control the treatment method, etching or forming. In a preferred embodiment two current-carrying electrodes are present on either side of the foil and two voltage electrodes are present between the current-carrying electrodes and the foil on either side thereof. This avoids contacting of the foil.
    Type: Grant
    Filed: March 28, 1983
    Date of Patent: February 5, 1985
    Assignee: U.S. Philips Corporation
    Inventors: Hendrik J. de Wit, Albertus W. M. Van Berlo, Cornelis Crevecoeur