Patents by Inventor Takafumi Oshima
Takafumi Oshima 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: 6770508Abstract: An ohmic electrode for an SiC semiconductor includes a p-type Si layer formed on the surface of a p-type SiC semiconductor, and a metal silicide layer formed on the surface of the Si layer, the metal silicide layer being formed from a metal silicide such as PtSi. The p-type Si layer is preferably formed from p-type Si having a carrier concentration equal to or higher than that of the aforementioned p-type SiC. Preferably, the ohmic electrode is formed as follows: deposition of Si is performed; deposition of a metal silicide is performed by means of laser ablation; laser irradiation is performed to thereby improve ohmic properties and enhance adhesion between the result deposition layer and the p-type SiC semiconductor, and then further deposition of the metal silicide is performed by means of laser ablation.Type: GrantFiled: November 24, 2003Date of Patent: August 3, 2004Assignee: NGK Spark Plug Co., Ltd.Inventors: Kenshiro Nakashima, Yasuo Okuyama, Hitoshi Yokoi, Takafumi Oshima
-
Publication number: 20040132202Abstract: In an ammonia sensor (1), lead portions (7) and (9) are provided on an insulating substrate (5); a pair of comb-shaped electrodes (11) and (13) are connected to the lead portions (7) and (9), respectively; a sensitive layer (15) is provided on the comb-shaped electrodes (11) and (13); and a protective layer (17) is provided on the sensitive layer (15). Particularly, the sensitive layer (15) is formed of a gas-sensitive raw material predominantly containing ZrO2 and containing at least W in an amount of 2 to 40 wt. % as reduced to WO3.Type: ApplicationFiled: September 25, 2003Publication date: July 8, 2004Applicant: NGK SPARK PLUG CO., LTD.Inventors: Hiroyuki Nishiyama, Shiro Kakimoto, Ryuji Inoue, Hitoshi Yokoi, Noboru Ishida, Takafumi Oshima, Satoshi Sugaya, Koichi Imaeda, Tadashi Hattori, Atsushi Satsuma
-
Patent number: 6743352Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected. Finally, the effect of the amount of moisture in the exhaust gas is removed or reduced from the detected value of gas concentration.Type: GrantFiled: February 6, 2002Date of Patent: June 1, 2004Assignee: NGK Spark Plug Co., Ltd.Inventors: Masashi Ando, Noboru Ishida, Satoshi Sugaya, Takafumi Oshima, Norihiko Nadanami, Takaki Otsuka, Yoshikuni Sato, Tatsuo Okumura, Yasuhisa Kuzuya
-
Publication number: 20040099866Abstract: An ohmic electrode for an SiC semiconductor includes a p-type Si layer formed on the surface of a p-type SiC semiconductor, and a metal silicide layer formed on the surface of the Si layer, the metal silicide layer being formed from a metal silicide such as PtSi. The p-type Si layer is preferably formed from p-type Si having a carrier concentration equal to or higher than that of the aforementioned p-type SiC. Preferably, the ohmic electrode is formed as follows: deposition of Si is performed; deposition of a metal silicide is performed by means of laser ablation; laser irradiation is performed to thereby improve ohmic properties and enhance adhesion between the resultant deposition layer and the p-type SiC semiconductor; and then further deposition of the metal silicide is performed by means of laser ablation.Type: ApplicationFiled: November 24, 2003Publication date: May 27, 2004Applicant: NGK SPARK PLUG CO., LTD.Inventors: Kenshiro Nakashima, Yasuo Okuyama, Hitoshi Yokoi, Takafumi Oshima
-
Patent number: 6695964Abstract: Method and sensor for measuring accurate measurement of NOx concentration in an exhaust gas containing O2,H2O, CO2 and NOx and a NOx gas concentration sensor. A first oxygen pump cell sufficiently pumps out oxygen in a measurement gas such as not to decompose NOx. A pair of electrodes is provided on an inner side and an outer side of a second measurement chamber into which the gas is introduced from a first measurement chamber via a diffusion resistance. A voltage is impressed across the paired electrodes for decomposing NOx in the second measurement chamber to dissociate oxygen which causes the current to flow in a second oxygen ion pump cell. The NOx gas concentration is measured for this current. The voltage impressed across the paired electrodes of the second oxygen ion pump cell is set so as not to dissociate H2O and CO2 present in the second measurement chamber.Type: GrantFiled: June 7, 2000Date of Patent: February 24, 2004Assignee: NGK Spark Plug Co., Ltd.Inventors: Masashi Ando, Noboru Ishida, Satoshi Sugaya, Takafumi Oshima, Norihiko Nadanami, Takaki Ootuka, Yoshikuni Sato, Tatsuo Okumura
-
Publication number: 20040026265Abstract: A hydrogen gas sensor capable of accurately measuring hydrogen concentration of a measurement gas atmosphere in the presence of a variety of interfering gasses such as H2O and CO. In the hydrogen gas sensor, the flow sectional area of a diffusion-rate limiting portion 6 is rendered small; the electrode surfaces of first and second electrodes 3 and 4 are rendered large; and/or a solution containing a polymer electrolyte which may be identical to that of a proton-conductive layer 2 is applied onto the surfaces of the first and second electrodes 3 and 4 to thereby form a layer containing the polymer electrolyte. Thus, the rate of conduction of protons from the first electrode 3 to the second electrode 4 becomes greater than the rate at which protons are derived from hydrogen which is introduced onto the first electrode 3 via the diffusion-rate limiting portion 6.Type: ApplicationFiled: July 29, 2003Publication date: February 12, 2004Applicant: NGK SPARK PLUG CO., LTD.Inventors: Norihiko Nadanami, Noboru Ishida, Takafumi Oshima, Ryuji Inoue, Tomonori Kondo
-
Publication number: 20040003664Abstract: A detecting-element assembly (40) is configured such that a piezoelectric element (51) is housed in a casing body portion (43) of a casing (42), and is attached to a housing portion (22) of a flow path formation member (20) via a flange portion (41). Therefore, the path between the piezoelectric element (51) and the position of attachment of the detecting-element assembly (40) is elongated, whereby ultrasonic waves which leak into the interior of the detecting-element assembly (40) from the piezoelectric element (51) become unlikely to reflectively return from a joint. Thus, the influence of, for example, noise stemming from reflected waves is reduced, thereby enhancing the accuracy of detection. An average clearance of 1 millimeter or more is provided along the outer circumferential surface of the casing body portion (43) of the detecting-element assembly (40), whereby a problem of collected foreign matter is unlikely to occur.Type: ApplicationFiled: April 9, 2003Publication date: January 8, 2004Applicant: NGK SPARK PLUG CO., LTD.Inventors: Hideki Ishikawa, Yoshikuni Sato, Keigo Banno, Masashi Sakamoto, Noboru Ishida, Takafumi Oshima
-
Patent number: 6652723Abstract: A hydrogen gas sensor capable of accurately measuring hydrogen concentration of a measurement gas atmosphere in the presence of a variety of interfering gasses such as H2O and CO. In the hydrogen gas sensor, the flow sectional area of a diffusion-rate limiting portion 6 is rendered small; the electrode surfaces of first and second electrodes 3 and 4 are rendered large; and/or a solution containing a polymer electrolyte which may be identical to that of a proton-conductive layer 2 is applied onto the surfaces of the first and second electrodes 3 and 4 to thereby form a layer containing the polymer electrolyte. Thus, the rate of conduction of protons from the first electrode 3 to the second electrode 4 becomes greater than the rate at which protons are derived from hydrogen which is introduced onto the first electrode 3 via the diffusion-rate limiting portion 6.Type: GrantFiled: November 21, 2000Date of Patent: November 25, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Norihiko Nadanami, Norobu Ishida, Takafumi Oshima, Ryuji Inoue, Tomonori Kondo
-
Patent number: 6647776Abstract: A split-flow-type flowmeter includes a detection element 2 disposed to face a flow path thereof and a venturi structure 4 formed within a flow path 1 in the vicinity of the detection element 2 and adapted to throttle a flow directed toward the detection element 2 to thereby reduce disturbance of the flow. The venturi structure 4 is disposed in opposition to the detection element 2 within the flow path 1 and includes a protrusion 5 protruding toward the detection element 2 within the flow path 1 of the split-flow-type flowmeter.Type: GrantFiled: May 7, 2002Date of Patent: November 18, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Yoshihiko Kohmura, Shunsuke Maeda, Takio Kojima, Takafumi Oshima
-
Patent number: 6635162Abstract: A gas sensor having a laminate structure composed of thin sheets of solid electrolyte and including a cavity portion 21 and an oxygen concentration cell 5. The oxygen concentration in the cavity portion 21 is held constant. The oxygen concentration cell 5 includes an active electrode 12 having a relatively high catalytic capability with respect to NOx or combustible gas and an inner common electrode 13/15 (serving as an inactive electrode and an oxygen-concentration-sensing electrode) having a relatively low catalytic capability with respect to NOx or combustible gas. The oxygen concentration cell 5 is disposed in the gas sensor so as to be exposed to the interior of the cavity portion 21. The concentration of NOx or combustible gas is determined based on an electromotive force (of the order of mV) generated between the active electrode 12 and the inner common electrode 13/15 by a concentration cell effect.Type: GrantFiled: September 17, 1999Date of Patent: October 21, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Satoshi Sugaya, Norihiko Nadanami, Noboru Ishida, Takafumi Oshima
-
Patent number: 6627964Abstract: A gas sensor having a pn junction including two discrete electrical conductive-type layers, namely, a first semiconductor layer and a second semiconductor layer, disposed in contact with each other. Ohmic electrodes are formed on the respective surfaces of the semiconductor layers. A catalytic layer containing a metallic catalytic component which dissociates hydrogen atom from a molecule having hydrogen atom is formed on one of the ohmic electrodes. The pn junction diode-type gas sensor has a simple constitution, exhibits a small change in diode characteristics with time in long-term service and is capable of detecting a gas concentration of a molecule having a hydrogen atom, for example, H2, NH3, H2S, a hydrocarbon and the like, contained in a sample gas.Type: GrantFiled: August 9, 2001Date of Patent: September 30, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Kenshiro Nakashima, Yasuo Okuyama, Hitoshi Yokoi, Takafumi Oshima
-
Patent number: 6578414Abstract: A split-flow-type flowmeter in which an end portion of a flow splitter tube 1 is inserted into a main-flow pipe 10 having a diameter D. A flow splitter tube 1 includes a U-shaped split-flow passage 1a. A detection element is disposed at a bottom portion (not shown) of the U-shaped split-flow passage 1a. The split-flow passage 1a assumes a flow path structure symmetrical with respect to a plane passing through the detection element. A flow inlet 2a and a flow outlet 2b of the split-flow passage 1a face in mutually opposite directions along the flow direction of the main-flow pipe 10 and open symmetrically at the same position on the flow cross section of the main-flow pipe 10.Type: GrantFiled: August 10, 2001Date of Patent: June 17, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Yoshihiko Kohmura, Shunsuke Maeda, Takio Kojima, Takafumi Oshima
-
Patent number: 6568281Abstract: An ultrasonic-wave propagation time measuring method which enables determination of accurate propagation time, a gas-pressure measuring method, a gas-flow-rate measuring method, and a gas sensor. A reception wave which has been transmitted and received by an ultrasonic element 5 is shaped and integrated by an integration circuit 67 to obtain an integral value. A peak value of the integral value is held by a peak-hold circuit 39. As to detection of gas concentration, a resistance-voltage-division circuit 41 sets a reference value on the basis of the peak value, and a point in time when the integral value of the reception wave is judged by a comparator 43 to have reached the reference value is regarded as an arrival time. Subsequently, a gas concentration is detected on the basis of a period between the emission time and the arrival time.Type: GrantFiled: August 11, 2000Date of Patent: May 27, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Yoshikuni Sato, Keigo Banno, Hideki Ishikawa, Noboru Ishida, Takafumi Oshima
-
Patent number: 6568240Abstract: The present invention provides a method and apparatus using a gas concentration sensor for accurately controlling an air fuel ratio in an internal combustion engine, featuring in that before the fuel-vaporized gas purged from the canister enters into the intake manifold whereat the sensor detects the gas concentration of the purged gas, the sensor is adjusted so as to adjust a zero point (or zero output level) of the sensor output. In step 100 of FIG. 7, a judgment is made as to whether the flow rate of air reaches a predetermined level. In step 110, processing for zero-point correction of the gas concentration sensor is performed. Specifically, in a state in which the purge valve 17 is closed, concentration of purge gas is measured by use of the gas concentration sensor 4, and a sensor output S1 at that time is obtained. Subsequently, the sensor output S1 is compared with a correct sensor output S0 in order to obtain a difference &Dgr;S therebetween.Type: GrantFiled: January 11, 2000Date of Patent: May 27, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Yoshikuni Sato, Noboru Ishida, Hideki Ishikawa, Takafumi Oshima, Yasushi Sato
-
Patent number: 6554984Abstract: A method of manufacturing a gas sensor, including a substrate electrode layer forming step, and a surface electrode layer forming step. The gas sensor includes first and second processing spaces, an oxygen concentration detection element, an oxygen pumping element, an oxidation catalyst and a combustible gas component concentration detection element.Type: GrantFiled: June 20, 2001Date of Patent: April 29, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Ryuji Inoue, Shoji Kitanoya, Kenji Kato, Tomohiro Fuma, Takafumi Oshima
-
Publication number: 20030070924Abstract: A gas sensor having a laminate structure composed of thin sheets of solid electrolyte and including a cavity portion 21 and an oxygen concentration cell 5. The oxygen concentration in the cavity portion 21 is held constant. The oxygen concentration cell 5 includes an active electrode 12 having a relatively high catalytic capability with respect to NOx or combustible gas and an inner common electrode 13/15 (serving as an inactive electrode and an oxygen-concentration-sensing electrode) having a relatively low catalytic capability with respect to NOx or combustible gas. The oxygen concentration cell 5 is disposed in the gas sensor so as to be exposed to the interior of the cavity portion 21. The concentration of NOx or combustible gas is determined based on an electromotive force (of the order of mV) generated between the active electrode 12 and the inner common electrode 13/15 by a concentration cell effect.Type: ApplicationFiled: September 17, 1999Publication date: April 17, 2003Inventors: SATOSHI SUGAYA, NORIHIKO NADANAMI, NOBORU ISHIDA, TAKAFUMI OSHIMA
-
Publication number: 20030066763Abstract: This invention provides a gas sensor including a proton-conductive polymer electrolyte layer and a method for measuring gas concentration, that are capable of measuring gas concentration at high accuracy nothwithstanding the presence of water vapor.Type: ApplicationFiled: May 15, 2002Publication date: April 10, 2003Applicant: NGK SPARK PLUG CO., LTD.Inventors: Masaya Watanabe, Norihiko Nadanami, Tomonori Kondo, Ryuji Inoue, Takafumi Oshima, Noboru Ishida
-
Publication number: 20030056586Abstract: A mass flow sensor includes a semiconductor substrate 1, an insulating thin film 2, heaters 311 and 312, temperature measurement resistors 321 and 322, and a protective layer 4. The heaters 311 and 312 are formed on the surface of the insulating thin film 2, and are provided adjacently such that the heater 311 is provided upstream the heater 312 and the heater 312 is provided downstream the heater 311. A cavity 5 is formed below the heaters 311 and 312, and the heaters are thermally insulated from the remaining portion of the semiconductor substrate. The temperature measurement resistors 321 and 322 are formed on the top surface of the insulating thin film 2, and are provided at opposite sides of the heaters 311 and 312, such that the resistors are aligned with respect to the flow passage of a fluid. In the mass flow sensor and the mass flowmeter including the sensor, the flow rate and flow direction of a fluid can be detected by means of merely the heaters 311 and 312, which are active elements.Type: ApplicationFiled: September 26, 2001Publication date: March 27, 2003Applicant: NGK SPARK PLUG CO., LTD.Inventors: Masatoshi Ueki, Takio Kojima, Yoshinori Tsujimura, Kouichi Ikawa, Yoshihiko Kohmura, Takafumi Oshima
-
Patent number: 6533911Abstract: A device and method for measuring combustible-gas concentration and a device and method for measuring hydrocarbon-gas concentration, which exhibit low dependence on oxygen concentration variations as well as low temperature dependence. Paste is applied to the inner surface of a closed-bottom cylindrical solid electrolyte element, thereby forming a layer serving as a reference electrode. Plating with platinum is performed, so as to form a layer serving as a first detection electrode, on the outer surface of the solid electrolyte element only at a portion extending from an end portion of the solid electrolyte element to the vicinity of the interface between a heating resistor and a heating-resistor lead portion, which are formed within a heater element contained in the cylindrical solid electrolyte element. Paste which contains gold powder and 10 parts of indium oxide is applied onto the platinum-plating layer so as to form a layer serving as a second detection electrode, followed by firing.Type: GrantFiled: June 9, 2000Date of Patent: March 18, 2003Assignee: NGK Spark Plug Co., Ltd.Inventors: Hiroki Fujita, Shoji Kitanoya, Kenji Kato, Tomohiro Fuma, Ryuji Inoue, Takafumi Oshima
-
Publication number: 20030042151Abstract: A method for detecting the concentration of a specific gas (NOx) in an engine exhaust gas using a gas sensor and a process of correcting the gas sensor. According to the correcting process, the amount of moisture in the exhaust gas is estimated, then a gas concentration detection signal output by the gas sensor on the basis of an estimated amount of moisture is corrected.Type: ApplicationFiled: February 6, 2002Publication date: March 6, 2003Applicant: NGK SPARK PLUG CO., LTD.Inventors: Masashi Ando, Noboru Ishida, Satoshi Sugaya, Takafumi Oshima, Norihiko Nadanami, Takaki Otsuka, Yoshikuni Sato, Tatsuo Okumura, Yasuhisa Kuzuya