Patents by Inventor Yukio Yokoyama

Yukio Yokoyama 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: 5866577
    Abstract: An anticoagulant agent which comprises, as an active ingredient, an aromatic amidine derivative represented by the following general formula (1) or a salt thereof: ##STR1## wherein the group represented by ##STR2## is a group selected from indolyl, benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, naphthyl, tetrahydronaphthyl and indanyl; X is a single bond, an oxygen atom, a sulfur atom or a carbonyl group; and Y is a saturated or unsaturated 5- or 6-membered heterocyclic moiety or cyclic hydrocarbon moiety optionally having a substituent group, an amino group optionally having a substituent group or an aminoalkyl group optionally having a substituent group.The inventive compound has a high anticoagulant capacity based on its excellent FXa inhibition activity.
    Type: Grant
    Filed: September 5, 1997
    Date of Patent: February 2, 1999
    Assignee: Daiichi Pharmaceutical Co., Ltd.
    Inventors: Takayasu Nagahara, Naoaki Kanaya, Kazue Inamura, Yukio Yokoyama
  • Patent number: 5620991
    Abstract: An anticoagulant agent which comprises, as an active ingredient, an aromatic amidine derivative represented by the following general formula (1) or a salt thereof: ##STR1## wherein the group represented by ##STR2## is a group selected from indolyl, benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, naphthyl, tetrahydronaphthyl and indanyl; X is a single bond, an oxygen atom, a sulfur atom or a carbonyl group; and Y is a saturated or unsaturated 5- or 6-membered heterocyclic moiety or cyclic hydrocarbon moiety optionally having a substituent group, an amino group optionally having a substituent group or an aminoalkyl group optionally having a substituent group.The inventive compound has a high anticoagulant capacity based on its excellent FXa inhibition activity.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: April 15, 1997
    Assignee: Daiichi Pharmaceutical Co., Ltd.
    Inventors: Takayasu Nagahara, Naoaki Kanaya, Kazue Inamura, Yukio Yokoyama
  • Patent number: 5576343
    Abstract: An anticoagulant agent which comprises, as an active ingredient, an aromatic amidine derivative represented by the following general formula (1) or a salt thereof: ##STR1## wherein the group represented by ##STR2## is a group selected from indolyl, benzofuranyl, benzothienyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, naphthyl, tetrahydronaphthyl and indanyl; X is a single bond, an oxygen atom, a sulfur atom or a carbonyl group; and Y is a saturated or unsaturated 5- or 6-membered heterocyclic moiety or cyclic hydrocarbon moiety optionally having a substituent group, an amino group optionally having a substituent group or an aminoalkyl group optionally having a substituent group.The inventive compound has a high anticoagulant capacity based on its excellent FXa inhibition activity.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: November 19, 1996
    Assignee: Daiichi Pharmaceutical Co., Ltd.
    Inventors: Takayasu Nagahara, Naoaki Kanaya, Kazue Inamura, Yukio Yokoyama
  • Patent number: 5493311
    Abstract: In order to achieve two-way communications at two different frequencies, an impedance matching circuit is coupled to an antenna. The circuit includes a first inductor which is directly coupled to the antenna. The first inductor induces antenna input impedance to be capacitive at a first resonant frequency and induces the antenna input impedance to be inductive at a second resonant frequency. The first resonant frequency is lower than the second resonant frequency. Further, a first capacitor is coupled to the first inductor. By providing the first capacitor, a reactance component at the first resonant frequency is rendered substantially equal to a reactance component at the second resonant frequency. Further, the circuit includes a second inductor and a second capacitor which are coupled between the second means and a feeder.
    Type: Grant
    Filed: February 28, 1994
    Date of Patent: February 20, 1996
    Assignee: NEC Corporation
    Inventors: Ryoh Itoh, Yukio Yokoyama, Takao Ono
  • Patent number: 5455595
    Abstract: An antenna mounted on and retractable into a casing of a portable radio communication apparatus. When the antenna is pulled out of the casing, it plays the role of a .lambda./2 whip antenna. Even when the antenna is retracted into the casing, it has substantially the same gain as when pulled out from the casing.
    Type: Grant
    Filed: January 26, 1994
    Date of Patent: October 3, 1995
    Assignee: NEC Corporation
    Inventors: Yukio Yokoyama, Kazuo Sekiya, Kenji Takamoro
  • Patent number: 5438339
    Abstract: A miniature and high performance antenna applicable to a radio communication apparatus and made up of a straight antenna rod and an antenna coil or coil element. A first whip antenna has a first portion retractable into the casing of the apparatus and a second portion constantly positioned externally of the casing. A second whip antenna has a coil element in the form of a loading coil having a predetermined number of turns. The second whip antenna is coaxially provided on the upper end of the first whip antenna and slidable relative to and in the axial direction of the first whip antenna. The second portion of the first whip antenna is movable between a position where one end of the coil element is disengaged from one end of the second portion and a position where the former is engaged with the latter. The antenna exhibits a desirable electric characteristic when pulled out of the casing of the apparatus and, in addition, promotes the efficient use of the limited space available in the casing.
    Type: Grant
    Filed: February 24, 1994
    Date of Patent: August 1, 1995
    Assignee: NEC Corporation
    Inventors: Ryoh Itoh, Yukio Yokoyama, Takao Ono
  • Patent number: 5394160
    Abstract: In a portable radio communication apparatus comprising an insulating case having an inner surface and a printed board housed in the insulating case, an antenna conductive film is coated on a predetermined region of the inner surface of the insulating case. A conductive ground film is coated on the remaining region of the inner surface of the insulating case with a constant gap from the outer periphery of the antenna. A first conductive member connects the antenna film with the conductive ground film. A plurality of second conductive members connect the conductive ground film with a ground pattern of a radio communication circuit on the printed board. A feeding member connects the antenna with an antenna terminal pad of the radio communication circuit. The second conductive members and feeding member are conductive rods.
    Type: Grant
    Filed: September 4, 1992
    Date of Patent: February 28, 1995
    Assignee: NEC Corporation
    Inventors: Hiroyuki Iwasaki, Yukio Yokoyama
  • Patent number: 5375256
    Abstract: A radio transceiver having improved impedance matching characteristics between a rod-like antenna and transmitting and receiving portions. An impedance matching circuit is provided between the antenna and a duplexer to impedance-match therebetween at a frequency within a desired signal frequency band. A transmitting signal and a receiving signal may have substantially different frequencies in which case the impedance matching circuit operates advantageously in a range between these signals, respectively. The impedance matching circuit includes a first inductor inserted between the antenna and the duplexer, a first capacitor inserted between the antenna and ground potential, and a parallel resonance circuit composed of a parallel circuit of a second capacitor and a second inductor inserted between the duplexer and ground potential.
    Type: Grant
    Filed: September 3, 1992
    Date of Patent: December 20, 1994
    Assignee: NEC Corporation
    Inventors: Yukio Yokoyama, Hiroyuki Iwasaki
  • Patent number: 5148181
    Abstract: A mobile radio communication apparatus with an improved antenna for promoting easy manual operations, insuring desirable acoustic characteristics, and preventing the antenna gain from being lowered by user's head or hand during communication. An antenna is mounted on the upper surface of a casing and made up of a rectangular first conductive plate parallel to and spaced apart from the upper surface by a predetermined distance and having a length L.sub.1, a rectangular second conductive plate extending perpendicularly from the first conductive plate and having a height H.sub.2, and a rectangular third conductive plate extending perpendicularly from the second conductive plate and in parallel to the first conductive plate. A short-circuiting plate extending perpendicularly from one side of the first conductive plate by a height H.sub.1 and has a length M as measured in a direction parallel to the length L.sub.1.
    Type: Grant
    Filed: December 10, 1990
    Date of Patent: September 15, 1992
    Assignee: NEC Corporation
    Inventors: Yukio Yokoyama, Takao Ono
  • Patent number: 5053943
    Abstract: In a system having plural CPUs, at least one of which is continuously operating and at least another of which is intermittently operating, autonomous counters monitor counter reset signal indicating normal operation of respective CPUs, each counter producing a CPU reset signal when it fails to receive a counter reset signal within a predetermined time period. To prevent erroneous indication of a malfunction and thus erroneous resetting of the CPUs when the intermittently operating CPU does not produce a counter reset signal within the predetermined time period while it is in its normal, non-operating state, a control circuit is provided to supply the autonomous counter monitoring the intermittently operating CPU with the counter reset signals produced by a continuously operating CPU while the intermittently operating CPU is in its non-operating state.
    Type: Grant
    Filed: November 28, 1989
    Date of Patent: October 1, 1991
    Assignee: NEC Corporation
    Inventor: Yukio Yokoyama
  • Patent number: 5042031
    Abstract: A configuration control method for a double loop communications system capable of handling simultaneously two different traffic modes for packet data and circuit-switched data, which includes a selector for connecting a token passing control circuit to either a hybrid multiplexer or a transmission line interface circuit to fully utilize the resources of the double loop transmission lines to increase the system throughput and handle both packet data and circuit-switched data in the event of fault occurrence without increasing the overhead for the fault recovery action.
    Type: Grant
    Filed: April 5, 1990
    Date of Patent: August 20, 1991
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Yukio Yokoyama, Tatsuki Ichihashi
  • Patent number: 4887476
    Abstract: A small engine provided with a self starter motor is suitable for use as a driving mechanism for hand-held or back-carried machines such as cleavers. As the engine is provided with a reduction drive gear loosely inserted over a cylindrical support concentrically provided with a crankshaft, and is so constructed that the rotation of the shelf starter motor is transmitted to the crankshaft via the reduction drive gear and an engagement/disengagement mechanism using centrifugal force, it is possible to improve the durability thereof and to simplify assembly operation.
    Type: Grant
    Filed: September 13, 1988
    Date of Patent: December 19, 1989
    Assignee: Tanaka Kogyo Co., Ltd.
    Inventor: Yukio Yokoyama
  • Patent number: 4791423
    Abstract: A low and broadband shorted microstrip antenna is disclosed which is mainly applicable to a mobile body in a mobile communication system. A first grounding conductive sheet which faces a radiating conductive sheet is provided at both ends thereof with a second and a third grounding conductive sheets which are perpendicular to the first grounding conductive sheet, whereby a beam tilt characteristic of the antenna is improved. The passive element and a conductive stub are disposed atop the grounding conductive sheet. The passive element and the conductive stub face the radiating conductive element and serve to improve the impedance matching parameter of the microstrip antenna.
    Type: Grant
    Filed: December 3, 1986
    Date of Patent: December 13, 1988
    Assignees: NEC Corporation, Nippon Telegraph & Telephone Corp.
    Inventors: Yukio Yokoyama, Yoshio Ebine, Toshio Ito
  • Patent number: 4680553
    Abstract: An intermediate frequency amplifier stage is disclosed, in which linearity of a signal strength detection output is improved. The intermediate frequency amplifier stage includes a plurality of intermediate frequency amplifiers, a plurality of double-wave rectifiers each coupled to the associated intermediate frequency amplifier and making full-wave rectification of the signal supplied from the associated intermediate frequency amplifier, and an adder circuit adding the rectification outputs of the respective double-wave rectifiers.
    Type: Grant
    Filed: November 22, 1985
    Date of Patent: July 14, 1987
    Assignee: NEC Corporation
    Inventors: Katsuji Kimura, Yoshihiko Kasai, Yukio Yokoyama, Koji Yamasaki, Toshifumi Sato
  • Patent number: 4644361
    Abstract: Unidirectivity is achieved in an antenna including a microstrip portion and a unipole portion. The microstrip portion includes a ground plane conductor, a radiation plane conductor dielectrically spaced from the ground plane conductor, and a conductive member connecting the radiation plane conductor to the ground plane conductor., The unipole portion of the antenna comprises a unipole coupled to the radiation plane conductor. The radiation fields of the microstrip and unipole portions intensify each other in a single direction to achieve unidirectivity.
    Type: Grant
    Filed: May 16, 1985
    Date of Patent: February 17, 1987
    Assignee: NEC Corporation
    Inventor: Yukio Yokoyama
  • Patent number: 4641366
    Abstract: In a portable radio communication apparatus comprising a handset (20) having a side surface (23) and a recessed surface (24), first and second antennae (51 and 52) of different resonance frequencies are fixed to the recessed surface by first and second conductive plates (55 and 56), respectively. First and second conductive lines (61 and 62) connect a common conductive line (63) to the first and the second antennae, respectively. The common conductive line is connected to an electro-audio and audio-electro converting device (30) to feed a transmitting electric signal to the first and the second antennae and to receive the received electric signal from the first and second antennae. The first and the second antennae have first and second antenna widths (W.sub.1 and W.sub.2), respectively. The first and the second conductive plates have first and second plate widths, respectively, and first and second axes centrally of the first and the second plate widths, respectively.
    Type: Grant
    Filed: October 3, 1985
    Date of Patent: February 3, 1987
    Assignees: NEC Corporation, Naohisa Goto
    Inventors: Yukio Yokoyama, Katsuji Kimura, Naohisa Goto