Having Heterojunction Or Graded Gap (epo) Patents (Class 257/E33.048)
  • Publication number: 20110057167
    Abstract: In the nitride based semiconductor optical device LE1, the strained well layers 21 extend along a reference plane SR1 tilting at a tilt angle ? from the plane that is orthogonal to a reference axis extending in the direction of the c-axis. The tilt angle ? is in the range of greater than 59 degrees to less than 80 degrees or greater than 150 degrees to less than 180 degrees. A gallium nitride based semiconductor layer P is adjacent to a light-emitting layer SP? with a negative piezoelectric field and has a band gap larger than that of a barrier layer. The direction of the piezoelectric field in the well layer W3 is directed in a direction from the n-type layer to the p-type layer, and the piezoelectric field in the gallium nitride based semiconductor layer P is directed in a direction from the p-type layer to the n-type layer. Consequently, the valence band, not the conduction band, has a dip at the interface between the light-emitting layer SP? and the gallium nitride based semiconductor layer P.
    Type: Application
    Filed: November 16, 2010
    Publication date: March 10, 2011
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Masaki UENO, Yohei ENYA, Takashi KYONO, Katsushi AKITA, Yusuke YOSHIZUMI, Takamichi SUMITOMO, Takao NAKAMURA
  • Publication number: 20100314606
    Abstract: A light-emitting device is disclosed, including a light-emitting element and a surface plasmon coupling element, having an intermediary layer connected to the light-emitting element and a metal structure on the intermediary layer, wherein the intermediary layer is conductive under low-frequency injection current and has the characteristics as dielectric material in a wavelength range 100 nm˜20000 nm.
    Type: Application
    Filed: August 19, 2009
    Publication date: December 16, 2010
    Applicant: NATIONAL TAIWAN UNIVERSITY
    Inventors: Chih-Chung Yang, Yen-Cheng Lu, Kun-Ching Shen, Fu-Ji Tsai, Jyh-Yang Wang, Cheng-Hung Lin, Chih-Feng Lu, Cheng-Yen Chen, Yean-Woei Kiang
  • Publication number: 20100231487
    Abstract: This light-emitting device includes a first electrode, a second electrode disposed opposite to the first electrode and a phosphor layer which is sandwiched between the first electrode and the second electrode and constituted by dispersing n-type semiconductor particles in a p-type semiconductor medium. A light-emitting device in another embodiment includes a first electrode, a second electrode disposed opposite to the first electrode and a phosphor layer which is sandwiched between the first electrode and the second electrode wherein a p-type semiconductor is segregated among the n-type semiconductor particles.
    Type: Application
    Filed: August 15, 2007
    Publication date: September 16, 2010
    Inventors: Eiichi Satoh, Shogo Nasu, Reiko Taniguchi, Toshiyuki Aoyama, Masayuki Ono, Kenji Hasegawa, Masaru Odagiri
  • Publication number: 20100202484
    Abstract: A semiconductor light emitting device, including: a heterojunction bipolar light-emitting transistor having a base region between emitter and collector regions; emitter, base, and collector electrodes for coupling electrical signals with the emitter, base, and collector regions, respectively; and a quantum size region in the base region; the base region including a first base sub-region on the emitter side of the quantum size region, and a second base sub-region on the collector side of the quantum size region; and the first and second base sub-regions having asymmetrical band structures.
    Type: Application
    Filed: January 7, 2010
    Publication date: August 12, 2010
    Inventors: Nick Holonyak, JR., Milton Feng, Gabriel Walter
  • Publication number: 20100193769
    Abstract: In accordance with the invention, a light source for display and/or illumination is provided, the light source comprising a heterostructure including semiconductor layers, the heterostructure forming a waveguide between a first end and a second end, the heterostructure comprising a plurality of layers and comprising an optically active zone formed by the plurality of layers, the optically active zone capable of emitting light guided by said waveguide, at least two different radiative transitions being excitable in the optically active an electrical current between a p-side electrode and an n-side electrode, transition energies of said at least two different radiative transitions corresponding to wavelengths in the visible part of the optical spectrum, the light source further comprising means for preventing reflections of light from the waveguide by at least one of said first and second end back into the waveguide, thereby causing the light source to comprise a superluminescent light emitting diode.
    Type: Application
    Filed: November 2, 2009
    Publication date: August 5, 2010
    Applicant: EXALOS AG
    Inventors: Lorenzo Occhi, Valerio Laino, Christian Velez
  • Publication number: 20100176420
    Abstract: A two-terminal mesa phototransistor and a method for making it are disclosed. The photo transistor has a mesa structure having a substantially planar semiconductor surface. In the mesa structure is a first semiconductor region of a first doping type, and a second semiconductor region of a second doping type opposite to that of the first semiconductor region, forming a first semiconductor junction with the first region. In addition, a third semiconductor region of the first doping type forms a second semiconductor junction with the second region. The structure also includes a dielectric layer. The second semiconductor region, first semiconductor junction, and second semiconductor junction each has an intersection with the substantially planar semiconductor surface. The dielectric covers, and is in physical contact with, all of the intersections.
    Type: Application
    Filed: January 14, 2010
    Publication date: July 15, 2010
    Inventor: Jie Yao
  • Publication number: 20100155752
    Abstract: A semiconductor light emitting device that includes a first conductive type semiconductor layer, a first electrode, a insulating layer, and an electrode layer. The first electrode has at least one branch on the first conductive type semiconductor layer. The insulating layer is disposed on the first electrode. The electrode layer is disposed on the insulating layer.
    Type: Application
    Filed: December 23, 2009
    Publication date: June 24, 2010
    Inventors: Woo Sik LIM, Sung Ho CHOO
  • Publication number: 20100139759
    Abstract: The present invention relates to an optical device and to a method of fabricating the same. In embodiments, the invention relates to a photovoltaic device or solar cell. The optical device comprises a first electrode and a second electrode and an active element disposed between the first and second electrodes. The active element comprising a plurality of semiconducting structures extending in a lengthwise direction from the first electrode and being in contact with the first and second electrodes; the active element comprises an np-junction. For the semiconducting structures, at least a part of the structures is of a general plate or flake shape. In embodiments, the semiconducting structures have at least one characteristic dimension in the nanometer range.
    Type: Application
    Filed: November 23, 2007
    Publication date: June 10, 2010
    Applicant: KOBENHAVNS UNIVERSITET
    Inventor: Martin Aagesen
  • Publication number: 20100110157
    Abstract: A method includes arranging a first bonding layer on a first functional region on a first substrate, or a region on a second substrate, bonding the first functional region to the second substrate through the first bonding layer, subjecting a first release layer to a first process to separate the first substrate from the first functional region at the first release layer, arranging a second bonding layer on a second functional region on the first substrate, or a region on a third substrate, bonding the second functional region to the second or third substrate through the second bonding layer, and subjecting a second release layer to a second process to separate the first substrate from the second functional region at the second release layer.
    Type: Application
    Filed: November 3, 2009
    Publication date: May 6, 2010
    Applicant: CANON KABUSHIKI KAISHA
    Inventors: Takao Yonehara, Yasuyoshi Takai
  • Publication number: 20100078623
    Abstract: A method for enhancing operation of a bipolar light-emitting transistor includes the following steps: providing a bipolar light-emitting transistor having emitter, base, and collector regions; providing electrodes for coupling electrical signals with the emitter, base, and collector regions; and adapting the base region to promote carrier transport from the emitter region toward the collector region by providing, in the base region, several spaced apart quantum size regions of different thicknesses, with the thicknesses of the quantum size regions being graded from thickest near the collector to thinnest near the emitter.
    Type: Application
    Filed: July 31, 2006
    Publication date: April 1, 2010
    Inventors: Milton Feng, Nick Holonyak, JR.
  • Patent number: 7683396
    Abstract: A high power light emitting device assembly with electro-static-discharge (ESD) protection ability and the method of manufacturing the same, the assembly comprising: at least two sub-mounts, respectively being electrically connected to an anode electrode and a cathode electrode, each being made of a metal of high electric conductivity and high thermal conductivity; a light emitting device, arranged on the sub-mounts; and an ESD protection die, sandwiched and glued between the sub-mounts, for enabling the high-power operating light emitting device to have good heat dissipating path while preventing the same to be damaged by transient power overload of static surge.
    Type: Grant
    Filed: October 18, 2006
    Date of Patent: March 23, 2010
    Assignee: Industrial Technology Research Institute
    Inventors: Ming-Chieh Chou, Wen-Shan Lin, Hung-Hsin Tsai
  • Patent number: 7675076
    Abstract: A light-emitting device has a main semiconductor region formed via an n-type AlInGaN buffer region on a p-type silicon substrate, the latter being sufficiently electroconductive to provide part of the current path through the device. Constituting the primary working part of the LED, the main semiconductor region comprises an n-type GaN layer, an active layer, and a p-type GaN layer, which are successively epitaxially grown in that order on the buffer region. A heterojunction is created between p-type substrate and n-type buffer region. Carrier transportation from substrate to buffer region is expedited by the interface levels of the heterojunction, with a consequent reduction of the drive voltage requirement of the LED.
    Type: Grant
    Filed: March 15, 2006
    Date of Patent: March 9, 2010
    Assignee: Sanken Electric Co., Ltd.
    Inventors: Koji Otsuka, Tetsuji Moku, Junji Sato, Yoshiki Tada, Takashi Yoshida
  • Patent number: 7671375
    Abstract: A light-emitting diode is built on a silicon substrate which has been doped with a p-type impurity to possess sufficient conductivity to provide part of the current path through the LED. The p-type silicon substrate has epitaxially grown thereon a buffer region of n-type AlInGaN. Further grown epitaxially on the buffer region is the main semiconductor region of the LED which comprises a lower confining layer of n-type GaN, an active layer for generating light, and an upper confining layer of p-type GaN. In the course of the growth of the buffer region and main semiconductor region there occurs a thermal diffusion of gallium and other Group III elements from the buffer region into the p-type silicon substrate, with the consequent creation of a p-type low-resistance region in the substrate. Interface levels are created across the heterojunction between p-type silicon substrate and n-type buffer region.
    Type: Grant
    Filed: March 17, 2006
    Date of Patent: March 2, 2010
    Assignee: Sanken Electric Co., Ltd.
    Inventors: Koji Otsuka, Tetsuji Moku, Junji Sato, Yoshiki Tada, Takashi Yoshida
  • Publication number: 20090272972
    Abstract: A ZnO based semiconductor light emitting device includes: a first semiconductor layer containing ZnO1-x1Sx1; a second semiconductor layer formed above the first semiconductor layer and containing ZnO1-x2Sx2; and a third semiconductor layer formed above the second semiconductor layer and containing ZnO1-x3Sx3, wherein an S composition x1 of the first semiconductor layer, an S composition x2 of the second semiconductor layer and an S composition x3 of the third semiconductor layer are so selected that an energy of the second semiconductor layer at the lower end of a conduction band becomes lower than both energies of the first and third semiconductor layers at the lower end of the conduction bands, and that an energy of the second semiconductor layer at the upper end of a valence band becomes higher than both energies of the first and third semiconductor layers at the upper end of the valence bands.
    Type: Application
    Filed: July 13, 2009
    Publication date: November 5, 2009
    Applicant: STANLEY ELECTRIC CO., LTD.
    Inventors: Akio Ogawa, Michihiro Sano, Hiroyuki Kato, Hiroshi Kotani, Tomofumi Yamamuro
  • Patent number: 7601985
    Abstract: A semiconductor light-emitting device includes: a substrate; a first conductivity type layer formed on the substrate and including a plurality of group III-V nitride semiconductor layers of a first conductivity type; an active layer formed on the first conductivity type layer; and a second conductivity type layer formed on the active layer and including a group III-V nitride semiconductor layer of a second conductivity type. The first conductivity type layer includes an intermediate layer made of AlxGa1?x?yInyN (wherein 0.001?x<0.1, 0<y<1 and x+y<1).
    Type: Grant
    Filed: September 15, 2006
    Date of Patent: October 13, 2009
    Assignee: Panasonic Corporation
    Inventors: Yoshitaka Kinoshita, Hidenori Kamei
  • Publication number: 20090242904
    Abstract: A semiconductor light emitting apparatus is supplied capable of providing a high performance that can optimize simultaneously both an electrical characteristic and a light emitting characteristic.
    Type: Application
    Filed: December 31, 2008
    Publication date: October 1, 2009
    Applicant: Oki Data Corporation
    Inventors: Yusuke NAKAI, Hironori FURUTA, Hiroyuki FUJIWARA, Mitsuhiko OGIHARA
  • Patent number: 7592632
    Abstract: A small-sized and high-efficiency light emitting device capable of easily emitting green light includes a resonator including a photonic crystal having a refractive-index periodic structure and a point defect member formed in the photonic crystal to disturb the refractive-index periodic structure, and an active member provided inside the resonator and formed by an In containing nitride semiconductor, wherein a wavelength determined by a band gap energy of the active member is included in a photonic band gap range of the photonic crystal, and is set to be shorter than a peak wavelength at a shortest-wavelength side of a resonance mode of the resonator in the photonic band gap range.
    Type: Grant
    Filed: September 25, 2007
    Date of Patent: September 22, 2009
    Assignee: Canon Kabushiki Kaisha
    Inventor: Akinari Takagi
  • Patent number: 7589347
    Abstract: A lateral junction semiconductor device and method for fabricating the same comprising the steps of taking a semiconductor structure having a stack formed by a plurality of layers of semiconductor material arranged in a series of substantially parallel planes, the semiconductor material within a first layer having an excess of charge carriers of a first polarity at a first concentration, and selectively removing semiconductor material from the first layer to a depth which varies along a first direction substantially parallel with the planes of the layers within the structure, so as to provide a gradation of the concentration of charge carriers of first polarity within an active layer along the first direction. A photon source comprising said lateral junction semiconductor device.
    Type: Grant
    Filed: August 2, 2005
    Date of Patent: September 15, 2009
    Assignee: Qinetiq Limited
    Inventors: Geoffrey Richard Nash, John Henry Jefferson, Keith James Nash
  • Publication number: 20090159907
    Abstract: A high fill factor textured light emitting diode structure comprises: a first textured cladding and contact layer (2) comprising a doped III-V or II-VI group compound semiconductor or alloys of such semiconductors deposited by epitaxial lateral overgrowth (ELOG) onto a patterned substrate (1); a textured undoped or doped active layer (3) comprising a III-V or II-VI group semiconductor or alloys of such semiconductors and where radiative recombination of electrons aid holes occurs or intersubband transition occurs; and a second textured cladding and contact layer (4) comprising a doped III-V or II-VI group semiconductor or alloys of such semiconductors.
    Type: Application
    Filed: September 27, 2005
    Publication date: June 25, 2009
    Inventor: Wang Nang Wang
  • Patent number: 7531440
    Abstract: A semiconductor laser device includes an n-type cladding layer 103 made of n?type (Al0.3Ga0.7)0.5In0.5P, an undoped active layer 104 and a first p-type cladding layer 105 made of p?type (Al0.3Ga0.7)0.5In0.5P. These layers are successively stacked in bottom-to-top order. The active layer 104 has a multi-quantum well structure composed of a first optical guide layer of undoped Al0.4Ga0.6As, a layered structure in which well layers of undoped GaAs and barrier layers of undoped Al0.4Ga0.6As are alternately formed, and a second optical guide layer of undoped Al0.4Ga0.6As. The first optical guide layer, the layered structure and the second optical guide layer are successively stacked in bottom-to-top order.
    Type: Grant
    Filed: July 18, 2007
    Date of Patent: May 12, 2009
    Assignee: Panasonic Corporation
    Inventor: Tsutomu Ukai
  • Publication number: 20090040418
    Abstract: A LED device of the present invention includes a substrate comprising a Cu and/or Al; a diamond-like carbon layer disposed on the substrate; an electric circuit formed on the diamond-like carbon layer; and a LED chip electrically connected to the electric circuit. The LED can be used as a light source of back light of liquid crystal display.
    Type: Application
    Filed: August 10, 2007
    Publication date: February 12, 2009
    Applicant: E. I. DUPONT DE NEMOURS AND COMPANY
    Inventors: Shin-Ming Kao, Yu-Cheng Lin, Jaw-Shin Cheng
  • Publication number: 20090014712
    Abstract: A tunnel junction light emitting device according to the present invention is provided with an active layer and an electron tunneling region supplying the active layer with carriers. The electron tunneling region has a first p-type semiconductor layer, a second p-type semiconductor layer and an n-type semiconductor layer. The second p-type semiconductor layer is sandwiched between the first p-type semiconductor layer and the n-type semiconductor layer, and the first p-type semiconductor layer, the second p-type semiconductor layer and the n-type semiconductor layer form a tunnel junction to which a reverse bias is applied. An energy level at a valence band edge of the second p-type semiconductor layer is equal to or lower than an energy level at a valence band edge of the first p-type semiconductor layer.
    Type: Application
    Filed: March 15, 2006
    Publication date: January 15, 2009
    Applicant: NEC CORPORATION
    Inventor: Naofumi Suzuki
  • Publication number: 20080308823
    Abstract: A light-generating semiconductor region is grown by epitaxy on a silicon substrate. The light-generating semiconductor region is a lamination of layers of semiconducting nitrides containing a Group III element or elements. The silicon substrate has a p-type impurity-diffused layer formed therein by thermal diffusion of the Group III element or elements from the light-generating semiconductor region as a secondary product of the epitaxial growth of this region on the substrate. The p-type impurity-diffused layer is utilized as a part of overvoltage protector diodes which are serially interconnected with each other and in parallel with the LED section of the device between a pair of electrodes.
    Type: Application
    Filed: July 28, 2008
    Publication date: December 18, 2008
    Applicant: Sanken Electric Co., Ltd.
    Inventors: Yasuhiro Kamii, Arei Niwa, Junji Sato, Mikio Tazima
  • Publication number: 20080283852
    Abstract: A light-emitting device and a method to from the device are is described. The device described herein may realize the transversely single mode operation by the buried mesa configuration even when the active layer contains aluminum. The method provides a step to form the mesa on a semiconductor substrate with an average dislocation density of 500 to 5000 cm?2, a step to form a protection layer, which prevents the active layer from oxidizing, at least on a side of the active layer, and a step to from a blocking layer so as to cover the protection layer and to bury the mesa.
    Type: Application
    Filed: May 13, 2008
    Publication date: November 20, 2008
    Inventors: Yukihiro TSUJI, Kenji Hiratsuka, Mitsuo Takahashi
  • Publication number: 20080179605
    Abstract: A nitride semiconductor light emitting device includes: a dielectric layered film over a substrate, the dielectric layered film being formed by stacking a plurality of dielectric films having different compositions; a semiconductor thin film formed of a single crystal over the dielectric layered film; and a pn junction diode structure over the semiconductor thin film, the pn junction diode structure being formed of a nitride semiconductor.
    Type: Application
    Filed: November 8, 2007
    Publication date: July 31, 2008
    Inventors: Yuji TAKASE, Tetsuzo Ueda, Tsuyoshi Tanaka, Daisuke Ueda
  • Publication number: 20080179606
    Abstract: A nitride semiconductor light emitting device includes a substrate formed of silicon, an insulating film formed on the substrate and a single crystal thin film formed on the insulating film. On the single crystal film, a semiconductor laminated body including a light emitting layer of nitride semiconductor is formed.
    Type: Application
    Filed: January 9, 2008
    Publication date: July 31, 2008
    Inventors: Manabu USUDA, Tetsuzo Ueda, Kenji Orita
  • Publication number: 20080121906
    Abstract: A method for producing a semiconductor light-emitting device includes stacking at least a first conductive type semiconductor layer (2), an active layer (3) and a second conductive type semiconductor layer (4) on a substrate (1) to form a wafer, then forming on a side of growth surfaces of the semiconductor layers first trenches (40) exposing the first conductive type semiconductor layer, further forming second trenches (50) reaching the substrate from above the first trenches by using a laser beam, subsequently forming third trenches (60) from the substrate at the positions corresponding to the second trenches, and finally cutting the wafer into chips. The produced semiconductor chips provide an enhanced efficiency of extracting emitted light even when the end faces thereof are smooth surfaces and they allow the semiconductor layer to be cut without distorting the end faces of the chips.
    Type: Application
    Filed: August 17, 2005
    Publication date: May 29, 2008
    Inventor: Kenji Yakushiji
  • Publication number: 20080087876
    Abstract: A lateral junction semiconductor device and method for fabricating the same comprising the steps of taking a semiconductor structure having a stack formed by a plurality of layers of semiconductor material arranged in a series of substantially parallel planes, the semiconductor material within a first layer having an excess of charge carriers of a first polarity at a first concentration, and selectively removing semiconductor material from the first layer to a depth which varies along a first direction substantially parallel with the planes of the layers within the structure, so as to provide a gradation of the concentration of charge carriers of first polarity within an active layer along the first direction. A photon source comprising said lateral junction semiconductor device.
    Type: Application
    Filed: August 2, 2005
    Publication date: April 17, 2008
    Inventors: Geoffrey Nash, John Henry Jefferson, keith Nash
  • Patent number: 7348602
    Abstract: The present invention provides a nitride semiconductor light emitting device with an active layer of the multiple quantum well structure, in which the device has an improved luminous intensity and a good electrostatic withstanding voltage, thereby allowing the expanded application to various products. The active layer 7 is formed of a multiple quantum well structure containing InaGa1?aN (0?a<1). The p-cladding layer 8 is formed on said active layer containing the p-type impurity. The p-cladding layer 8 is mode of a multi-film layer including a first nitride semiconductor film containing Al and a second nitride semiconductor film having a composition different from that of said first nitride semiconductor film. Alternatively, the p-cladding layer 8 is made of single-layered layer made of AlbGa1?bN (0?b?1). A low-doped layer 9 is grown on the p-cladding layer 8 having a p-type impurity concentration lower than that of the p-cladding layer 8.
    Type: Grant
    Filed: October 18, 2004
    Date of Patent: March 25, 2008
    Assignee: Nichia Corporation
    Inventor: Koji Tanizawa
  • Publication number: 20080054249
    Abstract: A device having an optically active region includes a silicon substrate and a SiGe cladding layer epitaxially grown on the silicon substrate. The SiGe cladding layer includes a plurality of arrays of quantum dots separated by at least one SiGe spacing layer, the quantum dots being formed from a compound semiconductor material.
    Type: Application
    Filed: November 1, 2007
    Publication date: March 6, 2008
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventor: Ya-Hong Xie
  • Publication number: 20080014672
    Abstract: A semiconductor laser device comprises an n-type cladding layer 103 made of n? type (Al0.3Ga0.7)0.5In0.5P, an undoped active layer 104 and a first p-type cladding layer 105 made of p? type (Al0.3Ga0.7)0.5In0.5P. These layers are successively stacked in bottom-to-top order. The active layer 104 has a multi-quantum well structure composed of a first optical guide layer of undoped Al0.4Ga0.6As, a layered structure in which well layers of undoped GaAs and barrier layers of undoped Al0.4Ga0.6As are alternately formed, and a second optical guide layer of undoped Al0.4Ga0.6As. The first optical guide layer, the layered structure and the second optical guide layer are successively stacked in bottom-to-top order.
    Type: Application
    Filed: July 18, 2007
    Publication date: January 17, 2008
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
    Inventor: Tsutomu Ukai
  • Publication number: 20070057248
    Abstract: A nanodevice (1) for a desired function includes a substrate (11), a one-dimensional nanostructure (12), a functional layer (20) having a desired function, a conductive thin film electrode (30), and an insulating layer (40). The one-dimensional nanostructure is operatively extends from the substrate. The functional layer is surrounds at least a portion of the one-dimensional nanostructure. The conducting thin film electrode is surrounds/encompasses the functional layer. The insulating layer is positioned between the substrate and the conductive thin film electrode, thereby electrically insulating the one from the other. Further, the nanodevice can incorporate one or more functional units 50, each unit including a one-dimensional nanostructure and a respective functional layer. The units may or may not share the same conductive thin film electrode and/or insulating layer.
    Type: Application
    Filed: April 21, 2006
    Publication date: March 15, 2007
    Applicants: Tsinghua University, HON HAI Precision Industry CO., LTD.
    Inventors: Yuan Yao, Wei-Guo Chu, Shou-Shan Fan
  • Patent number: 7148518
    Abstract: A group-III nitride semiconductor stack comprises a single-crystal substrate, a first group-III nitride layer formed on a principal surface of the single-crystal substrate, a graded low-temperature deposited layer formed on the group-III nitride layer and made of nitride in which group-III element composition is continuously changed, and a second group-III nitride layer formed on the graded low-temperature deposited layer.
    Type: Grant
    Filed: March 23, 2004
    Date of Patent: December 12, 2006
    Inventors: Hideto Sugawara, Tsunenori Hiratsuka