Patents by Inventor Takao Tohda

Takao Tohda 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: 6350999
    Abstract: In an electron-emitting device, an electron supplying layer for supplying electrons is composed of an n-GaN layer. An electron transferring layer for moving electrons toward the surface is composed of non-doped (intrinsic) AlxGa1−xN (0≦x≦1) having a graded composition for the Al concentration x. A surface layer is composed of non-doped AlN having a negative electron affinity (NEA). The electron transferring layer composed of AlxGa1−xN has a band gap which is enlarged nearly continuously from the electron supplying layer to the surface layer and a negative electron affinity or a positive electron affinity close to zero. If such a voltage V as to render the surface electrode side positive is applied, the band of AlxGa1−xN is bent, whereby a current derived mainly from a diffused current flows from the electron supplying layer to the surface layer through the electron transferring layer. Thereby excellent electron emitting characteristic is obtained.
    Type: Grant
    Filed: November 29, 1999
    Date of Patent: February 26, 2002
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takeshi Uenoyama, Takao Tohda, Masahiro Deguchi, Makoto Kitabatake, Kentaro Setsune
  • Patent number: 6101164
    Abstract: An information recording and reproducing device includes an inorganic recording medium having at least one material selected from the group consisting of a phase change material, a shape changing material and a magnetic material. A conductive probe, which is proximate to or contacting a recording surface of the recording medium, is movable relative to the recording medium. Information is recorded by heating the recording medium in the area where the conductive probe is proximate or contacting to change a physical state therein. The area of the recording medium where the conductive probe is proximate or contacting is heated by applying voltage between the conductive probe and the recording medium.
    Type: Grant
    Filed: December 4, 1996
    Date of Patent: August 8, 2000
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroyuki Kado, Takao Tohda, Osamu Kusumoto, Kazuo Yokoyama
  • Patent number: 6008156
    Abstract: A thermal-sensitive color developing material containing metal particles and a matrix substance where the size of the metal particles irreversibly increase at room temperature due to cohesion, and a thermal-sensitive element using the thermal-sensitive color developing material are disclosed. The thermal-sensitive color developing material irreversibly develops a color at a temperature of room temperature or higher.
    Type: Grant
    Filed: December 5, 1997
    Date of Patent: December 28, 1999
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Ichiro Tanahashi, Takao Tohda, Hiroshi Kanno
  • Patent number: 5731598
    Abstract: The single electron tunnel device of this invention includes: a multiple tunnel junction layer including multiple tunnel junctions; and first and second electrodes for applying a voltage to the multiple tunnel junction layer, wherein the multiple tunnel junction layer includes an electrically insulating thin film and metal particles and/or semiconductor particles dispersed in the electrically insulating thin film.
    Type: Grant
    Filed: June 19, 1996
    Date of Patent: March 24, 1998
    Assignee: Matsushita Electric Industrial Co. Ltd.
    Inventors: Hiroyuki Kado, Takao Tohda, Ichiro Tanahashi, Yoshio Manabe
  • Patent number: 5700591
    Abstract: A phosphor thin film of a compound of zinc, cadmium, manganese or alkaline earth metals and an element of group VI is sandwiched by barrier layers having a larger energy gap than that of the phosphor thin film, and a plurality of the sandwich structures are accumulated thicknesswise to constitute a light-emitting device. The phosphor thin film ensures the confinement of injected electrons and holes within the phosphor thin film. The light-emitting device has a high brightness and a high efficiency.
    Type: Grant
    Filed: March 23, 1994
    Date of Patent: December 23, 1997
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Michio Okajima, Takao Tohda
  • Patent number: 5679888
    Abstract: The dynamic quantity sensor includes an electrically insulating substance layer and at least one pair of electrodes contacting the electrically insulating substance layer, wherein a plurality of conductive particles are dispersed in the electrically insulating substance layer so that a tunnel current flows when a voltage is applied between the at least one pair of electrodes, and a dynamic quantity relating to a distance between the conductive particles is detected based on the tunnel current.
    Type: Grant
    Filed: October 3, 1995
    Date of Patent: October 21, 1997
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takao Tohda, Hiroyuki Kado, Ichiro Tanahashi, Yoshio Manabe, Masaru Yoshida
  • Patent number: 5497656
    Abstract: An atomic force microscope is preferably used to observe a sample surface and measure a surface profile of a sample by making use of interatomic forces existing between a probing tip and the sample surface. The atomic force microscope includes a cantilever having a probing tip, a laser diode for emitting a laser beam, a lens for focusing the laser beam emitted from the laser diode on the cantilever, and a photodiode for detecting a light beam reflected from the cantilever to thereby detect the amount of deflection of the cantilever. The atomic force microscope further includes a mechanism for finely moving one of a sample and the cantilever in three different directions, and a controller or computer for controlling the mechanism and for imaging the sample surface based on the amount of deflection of the cantilever at a plurality of locations of the sample surface.
    Type: Grant
    Filed: February 23, 1995
    Date of Patent: March 12, 1996
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroyuki Kado, Takao Tohda
  • Patent number: 5473396
    Abstract: A novel type projection TV has a large size fluorescent screen bearing three kinds of dots or stripes of fluorescent material which emits visible lights of red, green and blue at excitation by UV-rays, which are emitted from UV-emitting CRTs' for red, green and blue pixel of image, respectively; and a mask having UV-light passing apertures or a lens array is disposed on light paths of the UV-rays to improve color purity,
    Type: Grant
    Filed: September 8, 1993
    Date of Patent: December 5, 1995
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Michio Okajima, Takao Tohda
  • Patent number: 5468959
    Abstract: A microscope comprises a cantilever having a distal end equipped with an electrically conductive probe allowing current to flow and having a fine tip whose voltage is controllable, a position control mechanism for controlling position of a sample with respect to a base end of the cantilever, a small displacement measuring mechanism for measuring a deflection amount of the cantilever, and a deflection control mechanism for controlling deflection of the cantilever so as to adjust a distance between the fine tip of the probe and the sample.
    Type: Grant
    Filed: March 18, 1994
    Date of Patent: November 21, 1995
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takao Tohda, Hiroyuki Kado, Shinichi Yamamoto
  • Patent number: 5381753
    Abstract: A fabrication method provides fine structures which have few carrier trap centers and light absorption levels and find applications in quantum wires and quantum boxes having arbitrary configurations at least within a two-dimensional plane. The fabrication method comprises the steps of having a sharp tip held in close proximity to the surface of a substrate 1 and having a metal constituting the tip evaporated from the top. Alternatively, a metal contained in ambient vapor or a solution decomposed by a tunnel current or the like is provided. The metal is deposited locally on the substrate surface. A finely structured crystal is grown on the locally deposited region by a vapor phase-liquid phase-solid phase reaction.
    Type: Grant
    Filed: April 30, 1993
    Date of Patent: January 17, 1995
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Michio Okajima, Osamu Kusumoto, Takao Tohda, Kazuo Yokoyama, Motoshi Shibata
  • Patent number: 5357787
    Abstract: A cantilever for an atomic force microscope, has a probe formed by a structure at least partially including a linear needle crystal. A method of manufacturing the cantilever comprises the steps of applying adhesive to a distal end portion of a cantilever body and placing on the adhesive, in a state where the cantilever body is held substantially horizontally, a structure having the shape of at least four needle crystals combined with one another so as to bond the structure to the distal end portion of the cantilever body.
    Type: Grant
    Filed: February 24, 1994
    Date of Patent: October 25, 1994
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroyuki Kado, Takao Tohda
  • Patent number: 5336369
    Abstract: A method of making a cantilever stylus for an atomic force microscope comprises forming a film on a surface of a substrate, the film comprising a stylus material that is different from the material of the substrate. A resist thin film of a material different from the stylus material is formed on the surface of the stylus material so as to have a tip. The stylus material is then etched with an isotropic etching technique to a depth of etching greater than the radius of curvature of the tip of the resist film so that the stylus material, having two opposite principal surfaces, has a tip formed on one of the principal surfaces with a radius of curvature less than 0.1 .mu.m which protrudes beyond a tip of the other principal surface. At least the resist thin film and the substrate at the tips of the principal surfaces of the stylus material are then removed.
    Type: Grant
    Filed: May 27, 1993
    Date of Patent: August 9, 1994
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroyuki Kado, Takao Tohda
  • Patent number: 5239863
    Abstract: An atomic force microscope for observing a sample surface (7) is internally provided with a cantilever stylus (1, 14, 23) and makes use of atomic forces acting between the cantilever stylus (1, 14, 23) and the sample surface. The cantilever stylus (1, 14, 23) includes a cantilever (2, 15, 22) having a fixed end and a free end and having two principal surfaces. The cantilever stylus (1, 14, 23) further includes two tip portions formed in the principal surfaces of the free end, respectively. One of the two tip portions has a radius of curvature less than 0.1 .mu.m and protrudes beyond the other tip portion so that the former may be used to observe the sample surface (7).
    Type: Grant
    Filed: May 14, 1991
    Date of Patent: August 31, 1993
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroyuki Kado, Takao Tohda
  • Patent number: 5186789
    Abstract: A cantilever stylus suited for use in an atomic force microscope is made in the following processes: forming a first film on a substrate; forming a second film of metallic material on an external surface of the first film; forming a photoresist film on an external surface of the second film by making use of a photolithography technique; performing etching with respect to the second film with only a portion thereof covered with the photoresist film left on the first film; and further performing etching with respect to the first film with the second film being used as a resist film so that the first film may be configured into a cantilever stylus.
    Type: Grant
    Filed: November 29, 1991
    Date of Patent: February 16, 1993
    Assignees: Agency of Industrial Science and Technology, Matsushita Electric Industrial Co., Ltd.
    Inventors: Nobuhiro Tsuda, Hirofumi Yamada, Hiroyuki Kado, Takao Tohda
  • Patent number: 4888246
    Abstract: A dielectric thin film element comprising a dielectric substrate and a dielectric thin film formed on the substrate. The thin film is made of a perovskite type oxide and formed by sputtering in an atmosphere containing nitrogen, by which the dielectric constant and the breakdown electric field strength are greatly improved. Thin film devices using the film and a method for making the thin film are also described.
    Type: Grant
    Filed: May 23, 1986
    Date of Patent: December 19, 1989
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Jun Kuwata, Yosuke Fujita, Takao Tohda, Atsushi Abe, Tomizo Matsuoka
  • Patent number: 4869973
    Abstract: In a thin film EL display device wherein a transparent electrode, a first dielectric layer, an EL emission layer, a second dielectric layer and a back electrode are laminated in order on a transluscent substrate, a 10 nm-200 nm thickness of thin film made of calcium sulfide or a mixture containing calcium sulfide which is formed by an electron beam vapor deposition method provided between the first dielectric layer and the EL emission layer and between the EL emission layer and the second dielectric layer, thereby obtaining a thin film EL display device which maintains a stable operation for a long period even when it is driven by A.C. pulses which are a symmetric with respect to the time relationship of the driving pulses (e.g.
    Type: Grant
    Filed: September 4, 1987
    Date of Patent: September 26, 1989
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Masahiro Nishikawa, Takao Tohda, Jun Kuwata, Yosuke Fujita, Tomizo Matsuoka, Atsushi Abe
  • Patent number: 4847609
    Abstract: An electroluminescent display panel formed of phosphor and dielectric layers sandwiched between opposing mutually intersecting arrays of drive electrodes, has the thickness of the phosphor layer set to a value which provides minimum power consumption, for a given level of display brightness. This is achieved by determining a value of capacitance per unit area of the panel which results in a maximum allowable value of time being required to charge each display element, then determining a value of phosphor layer thickness providing minimum power consumption, using the latter value of capacitance and the known value of light emission efficiency of the display.
    Type: Grant
    Filed: September 24, 1987
    Date of Patent: July 11, 1989
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Jun Kuwata, Yosuke Fujita, Takao Tohda, Masahiro Nishikawa, Tomizo Matsuoka, Atsushi Abe
  • Patent number: 4814668
    Abstract: An electroluminescent display device comprising an electroluminescent emitting layer including zinc oxide containing a luminescent active material, an insulating layer formed on one surface of the electroluminescent emitting layer and a pair of energizing means for applying signal voltages corresponding to an information to be displayed to a multilayer assembly including the said two layers, characterized in that a plurality of semiconductor layers each containing at least one chemical compound selected from the group consisting of chemical compounds of the II-VI groups and tin oxide are arranged as one of the energizing means arranged on the side of the electroluminescent emitting layer or between the energizing means arranged on the side of the electroluminescent emitting layer and the electroluminescent emitting layer. This device features that it requires only a reduced drive voltage for image displaying purposes and ensures an increased luminescent brightness.
    Type: Grant
    Filed: December 23, 1987
    Date of Patent: March 21, 1989
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Takao Tohda, Tomizo Matsuoka, Yosuke Fujita, Atsushi Abe, Tsuneharu Nitta
  • Patent number: 4733128
    Abstract: An electroluminescense display device having a emission layer comprising zinc sulfide characterized in that at least one member selected from the group consisting of rare earth elements, manganese, copper, silver, magnesium, aluminum and their halides is contained as an activator, as well as at least one member selected from the group consisting of nitrogen, phosphorus, arsenic and antimony is contained as a coactivator. Said emission layer is formed by sputtering by using, as a target, zinc sulfide containing said activator and coactivator. Said sputtering is conducted in an atmosphere comprising a rare gas or rare gas containing a sulfide gas. The electroluminescence display device of the present invention has a higher brightness than conventional device with a good repeatability.
    Type: Grant
    Filed: October 5, 1984
    Date of Patent: March 22, 1988
    Assignee: Matsushita Electric Industrial Co. Ltd.
    Inventors: Takao Tohda, Yosuke Fujita, Masahiro Nishikawa, Tomizo Matsuoka, Atsushi Abe, Tsuneharu Nitta
  • Patent number: 4634934
    Abstract: Electroluminescent display device suitable for ac and unipolar pulse voltage operation, and ensuring an increased luminescent brightness and a low driving voltage, comprises a transparent electrically insulating substrate; an electroluminescent layer comprised of zinc sulfide (ZnS) and at least one luminescingly active material; an electrically insulating layer formed on one surface of said electroluminescent layer; and first and second energizing means for applying signal voltages across said electroluminescent layer and said insulating layer corresponding to information to be displayed, wherein said first energizing means is interposed between said transparent substrate and said electroluminescent layer, and includes at least one semiconductive electrode which contacts said electroluminescent layer and is comprised of a semiconductive material containing at least one chemical compound selected from the group consisting of the chemical compounds of Groups II-VI, and wherein said second energizing means is ar
    Type: Grant
    Filed: January 18, 1984
    Date of Patent: January 6, 1987
    Assignee: Matsushita Electric Industrial Co. Ltd.
    Inventors: Takao Tohda, Tomizo Matsuoka, Yosuke Fujita, Atsushi Abe, Tsuneharu Nitta