Patents by Inventor Junichi Saeki

Junichi Saeki 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).

  • Publication number: 20020135051
    Abstract: A semiconductor device which can improve the connection reliability of solder bumps and productivity in manufacturing. Insulating tape having wiring patterns on its surface is bonded to a lead frame. Semiconductor elements are loaded and circuit formed surfaces and sides of the semiconductor elements are sealed with sealing resin. After arrangements of individual semiconductor devices are formed, the lead frame is separated into individual metal plates to form individual semiconductor devices. Such simultaneous production of a plurality of semiconductor devices enhances productivity, and improves flatness of the insulating tape, whereby the connection reliability of solder bumps is improved.
    Type: Application
    Filed: May 2, 2002
    Publication date: September 26, 2002
    Inventors: Asao Nishimura, Junichi Saeki
  • Patent number: 6326681
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the “Lead-On-Chip” or “Chip-On-Lead” structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: January 13, 2000
    Date of Patent: December 4, 2001
    Assignee: Hitachi, LTD
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6303982
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the “Lead-On-Chip” or “Chip-On-Lead” structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: January 30, 2001
    Date of Patent: October 16, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6291880
    Abstract: A semiconductor device includes a main circuit part having a semiconductor device formed on an electrode plate of a lead frame and a control circuit part having protective functions, which is integrally molded by a resin mold part into an integral mold structure.
    Type: Grant
    Filed: February 10, 1999
    Date of Patent: September 18, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Toshio Ogawa, Masaaki Takahashi, Masahiro Gouda, Noritaka Kamimura, Kazuhiro Suzuki, Junichi Saeki, Kazuji Yamada, Makoto Ishii, Akihiro Tamba
  • Publication number: 20010008302
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the “Lead-On-Chip” or “Chip-On-Lead” structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Application
    Filed: January 30, 2001
    Publication date: July 19, 2001
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto
  • Patent number: 6204552
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the “Lead-On-Chip” or “Chip-On-Lead” structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: January 12, 2000
    Date of Patent: March 20, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6130114
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: April 13, 1999
    Date of Patent: October 10, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjoh, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto
  • Patent number: 6124629
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: October 8, 1998
    Date of Patent: September 26, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6114192
    Abstract: A semiconductor plastic package, more particularly a preferred package structure and method for making a BGA package. A resin sealed BGA package where a supporting frame which fixedly supports semiconductor parts; i.e., an IC chip, a circuit board, or a circuit film, is sealed with resin, using a mold which is composed of an upper mold half and a lower mold half with the lower mold half having a plurality of projections, one at a position corresponding to each of the external terminals. The mold has a divisional structure which has an air vent between the divisional elements thereof.
    Type: Grant
    Filed: July 14, 1998
    Date of Patent: September 5, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Shigeharu Tsunoda, Junichi Saeki, Isamu Yoshida, Kazuya Ooji, Michiharu Honda, Makoto Kitano, Nae Yoneda, Shuji Eguchi, Kunihiko Nishi, Ichiro Anjoh, Kenichi Otsuka
  • Patent number: 6100580
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: October 7, 1998
    Date of Patent: August 8, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6100115
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: October 5, 1998
    Date of Patent: August 8, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6081023
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: April 9, 1999
    Date of Patent: June 27, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjoh, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto
  • Patent number: 6072231
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: April 28, 1998
    Date of Patent: June 6, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjoh, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto
  • Patent number: 6069029
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: April 15, 1998
    Date of Patent: May 30, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 6018191
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: March 5, 1998
    Date of Patent: January 25, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjoh, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto
  • Patent number: 5981315
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: October 6, 1998
    Date of Patent: November 9, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjoh, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto
  • Patent number: 5914530
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: April 1, 1998
    Date of Patent: June 22, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjoh, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 5914531
    Abstract: A semiconductor plastic package, more particularly a preferred package structure and method for making a BGA package. A resin sealed BGA package where a supporting frame which fixedly supports semiconductor parts; i.e., an IC chip, a circuit board, or a circuit film, is sealed with resin, using a mold which is composed of an upper mold half and a lower mold half with the lower mold half having a plurality of projections, one at a position corresponding to each of the external terminals. The mold has a divisional structure which has an air vent between the divisional elements thereof.
    Type: Grant
    Filed: February 25, 1997
    Date of Patent: June 22, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Shigeharu Tsunoda, Junichi Saeki, Isamu Yoshida, Kazuya Ooji, Michiharu Honda, Makoto Kitano, Nae Yoneda, Shuji Eguchi, Kunihiko Nishi, Ichiro Anjoh, Kenichi Otsuka
  • Patent number: 5863817
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: March 24, 1998
    Date of Patent: January 26, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsuro Matsumoto
  • Patent number: 5821606
    Abstract: As the semiconductor chip is large-sized, highly integrated and speeded up, it becomes difficult to pack the semiconductor chip together with leads in a package. In view of this difficulty, there has been adopted the package structure called the "Lead-On-Chip" or "Chip-On-Lead" structure in which the semiconductor and the leads are stacked and packed. In the package of this structure, according to the present invention, the gap between the leading end portions of the inner leads and the semiconductor chip is made wider than that between the inner lead portions except the leading end portions and the semiconductor chip thereby to reduce the stray capacity, to improve the signal transmission rate and to reduce the electrical noises.
    Type: Grant
    Filed: January 29, 1997
    Date of Patent: October 13, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Gen Murakami, Kunihiro Tsubosaki, Masahiro Ichitani, Kunihiko Nishi, Ichiro Anjo, Asao Nishimura, Makoto Kitano, Akihiro Yaguchi, Sueo Kawai, Masatsugu Ogata, Syuuji Eguchi, Hiroyoshi Kokaku, Masanori Segawa, Hiroshi Hozoji, Takashi Yokoyama, Noriyuki Kinjo, Aizo Kaneda, Junichi Saeki, Shozo Nakamura, Akio Hasebe, Hiroshi Kikuchi, Isamu Yoshida, Takashi Yamazaki, Kazuyoshi Oshima, Tetsurou Matsumoto