Patents by Inventor Yuji Yokoyama

Yuji Yokoyama has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5932901
    Abstract: A semiconductor memory device comprising: a first insulating film covering the upper and side surfaces of a gate electrode; a second insulating film formed on the substrate covering the first insulating film; a pair of contact holes formed through the second insulating film and reaching the impurity diffusion regions; a conductive plug embedded in one of the contact holes; a third insulating film formed on the second insulating film covering the conductive plug, and having a first aperture on the other contact hole; a bit line formed on the third insulating film and connected to the other impurity diffusion region through the first aperture and the other contact hole; a fourth insulating film covering the upper and side surfaces of the bit line; a second aperture formed through the third insulating film in alignment with the fourth insulating film covering the side surface of the bit line; a storage electrode formed to extend over the bit line, insulated from the bit line by the third and fourth insulating fi
    Type: Grant
    Filed: July 10, 1997
    Date of Patent: August 3, 1999
    Assignee: Fujitsu Limited
    Inventors: Kazuo Itabashi, Osamu Tsuboi, Yuji Yokoyama, Kenichi Inoue, Koichi Hashimoto, Wataru Futo
  • Patent number: 5787043
    Abstract: A semiconductor device is provided which comprises a memory mat formed by dividing a memory into a plurality of blocks and a circuit arrangement disposed at every memory mat block for generating access suppression signals at least for defective memory cells within that block. Using this arrangement, the access speed to a redundant memory cell array for relieving the defects is increased so that a semiconductor memory device capable of a high speed operation is obtained.
    Type: Grant
    Filed: February 27, 1995
    Date of Patent: July 28, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Akioka, Yuji Yokoyama, Atsushi Hiraishi, Masahiro Iwamura, Yutaka Kobayashi, Tatsumi Yamauchi, Shigeru Takahashi, Koichi Motohashi
  • Patent number: 5777952
    Abstract: A bias magnet unit has a permanent magnet that applies a bias magnetic field to an optical spot on a magneto-optical disk. A driving coil rotates the magnet in order to change a polarity of the bias magnetic field. A sensor detects the intensity and polarity of the bias magnetic field to confirm the rotational position of the magnet after it has been rotated. A linkage structure that is connected between a magnet holder of the magnet unit and the housing has arms that drive the magnet unit between two positions, one in which the magneto-optical disk cartridge can be inserted into the device and another in which the disk is loaded onto the spindle motor for recording/playback. Overall, the components of the device cooperate structurally to provide a relatively thin device structure having low power consumption.
    Type: Grant
    Filed: July 11, 1996
    Date of Patent: July 7, 1998
    Assignees: Hitahi, Ltd., Hitachi Computer Peripherals Co., Ltd.
    Inventors: Hajime Nishimura, Atsushi Ichikawa, Akio Yabe, Yuji Yokoyama
  • Patent number: 5680066
    Abstract: A semiconductor device which includes at least one of (1) an input buffer circuit formed of an input level converter and a non-inverting buffer circuit and an inverting buffer circuit each including BiCMOS circuitry which effects high-speed operation; (2) a decoder circuit formed of plural logic gates each of which is composed of the combination of MOS and bipolar circuitry; (3) a sense amplifier circuit including a multiemitter transistor; (4) a signal or address transition detector circuit which includes input circuits each receiving, for example, an address signal of a voltage amplitude and outputting a current amplitude signal in response to a change in level of the address signal, and a detector circuit connected thereto which has a cascode amplifier arranged such that it receives current amplitude signals at an input thereof and in which the cascode amplifier input is maintained at a substantially constant voltage, in which the detection circuit detects a transition of one or more of the current amplitu
    Type: Grant
    Filed: January 13, 1994
    Date of Patent: October 21, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Akioka, Masahiro Iwamura, Atsushi Hiraishi, Yuji Yokoyama, Nozomu Matsuzaki, Tatsumi Yamauchi, Yutaka Kobayashi, Nobuyuki Gotou, Akira Ide, Masahiro Yamamura, Hideaki Uchida
  • Patent number: 5675548
    Abstract: An arrangement which is particularly effective for decoders in semiconductor memory circuits which use, for example, common NMOS to receive one input for a plurality of logic decoder gates is provided includes a plurality of logic gates each having a first input terminal for respectively receiving first input signals and each being coupled to a common node. In one embodiment, first and second switching elements are also coupled to the common node. The first and second switching elements are both coupled to a second input terminal for receiving a second input signal which is common to the plurality of logic gates, and both operate complementary to one another in response to the second input signal. An improved read/write arrangement is also provided for such semiconductor memory circuit which includes circuitry to prevent connection of a common read line to the data lines during the writing operation. This enhances the writing speed by removing the load of the common read line during writing.
    Type: Grant
    Filed: February 29, 1996
    Date of Patent: October 7, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Yuji Yokoyama, Takashi Akioka, Masahiro Iwamura, Atsushi Hiraishi, Yutaka Kobayashi, Tatsumi Yamauchi, Shigeru Takahashi, Nobuyuki Gotou, Akira Ide
  • Patent number: 5619151
    Abstract: A semiconductor memory device which includes at least one of (1) an input buffer circuit which generates internal address signals in response to an incoming address; (2) a decoder circuit formed of plural logic gates each of which is composed of the combination of MOS and bipolar circuitry; (3) a sense amplifier circuit including a multiemitter transistor; (4) a signal or address transition detector circuit which includes input circuits each receiving, for example, an address signal of a voltage amplitude and outputting a current amplitude signal in response to a change in level of the address signal, and a detector circuit connected thereto which has a cascode amplifier arranged such that it receives current amplitude signals at an input thereof and in which the cascode amplifier input is maintained at a substantially constant voltage, in which the detection circuit detects a transition of one or more of the current amplitude signals and, in response thereto, generates an ATD signal of a voltage amplitude; a
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: April 8, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Akioka, Masahiro Iwamura, Atsushi Hiraishi, Yuji Yokoyama, Nozomu Matsuzaki, Tatsumi Yamauchi, Yutaka Kobayashi, Nobuyuki Gotou, Akira ide, Masahiro Yamamura, Hideaki Uchida
  • Patent number: 5619455
    Abstract: A pipeline-operating type memory system is arranged to have a first input unit for receiving a selector address signal for selecting data; a second input unit for receiving at least an address strobe signal, an X address signal and a Y address signal for selecting data; a first unit for receiving the X address signal and the Y address signal, latching these signals utilizing a first clock signal, and continuously outputting at least either of the X and the Y address signals until these address signals are unlatched; and a second unit for latching a selector address data signal output from the first input unit utilizing the first clock signal, and continuously and selectively outputting at least either of the address signal until the signal is unlatched. The memory system operates to transfer data in a manner to suit the pipeline operating cycle at a normal operating mode and at a fast page mode.
    Type: Grant
    Filed: March 23, 1993
    Date of Patent: April 8, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Noboru Akiyama, Yuji Yokoyama, Tatsuyuki Ohta, Kunihiko Suzuki, Yutaka Kobayashi
  • Patent number: 5602782
    Abstract: A pipeline-operating type memory system is arranged to have a first input unit for receiving a selector address signal for selecting data, a second input unit for receiving at least an address strobe signal, an X address signal and a Y address signal for selecting data; a first unit for receiving the X address signal and the Y address signal, latching these signals utilizing a first clock signal, and continuously outputting at least either of the X and the Y address signals until these address signals are unlatched; and a second unit for latching a selector address data signal output from the first input unit utilizing the first clock signal, and continuously and selectively outputting at least either of the address signal until the signal is unlatched. The memory system operates to transfer data in a manner to suit the pipeline operating cycle at a normal operating mode and at a fast page mode.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: February 11, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Noboru Akiyama, Yuji Yokoyama, Tatsuyuki Ohta, Kunihiko Suzuki, Yutaka Kobayashi
  • Patent number: 5544125
    Abstract: An arrangement which is particularly effective for decoders in semiconductor memory circuits which use, for example, common NMOS to receive one input for a plurality of logic decoder gates is provided includes a plurality of logic gates each having a first input terminal for respectively receiving first input signals, and each being coupled to a common node. In one embodiment, first and second switching elements are also coupled to the common node. The first and second switching elements are both coupled to a second input terminal for receiving a second input signal which is common to the plurality of logic gates, and both operate complementary to one another in response to the second input signal. An improved read/write arrangement is also provided for such semiconductor memory circuits which includes circuitry to prevent connection of a common read line to the data lines during the writing operation. This enhances the writing speed by removing the load of the common read line during writing.
    Type: Grant
    Filed: February 6, 1995
    Date of Patent: August 6, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Yuji Yokoyama, Takashi Akioka, Masahiro Iwamura, Atsushi Hiraishi, Yutaka Kobayashi, Tatsumi Yamauchi, Shigeru Takahashi, Nobuyuki Gotou, Akira Ide
  • Patent number: 5502820
    Abstract: An improved buffer circuit arrangement is provided which is particularly useful for semiconductor integrated circuit semiconductor memories and microprocessors. The buffer circuit is capable of switching large loads in various types of LSIs, and features a low noise and high speed circuit operation. This is accomplished by a parallel connection of output transistors in an output buffer circuit, and by differentiating the starting time of operation between the output transistors connected in parallel without using a delay circuit. For example, differentiating the starting times can be achieved by either providing the transistors with different characteristics from one another or the driving circuits with different characteristics from one another. Another aspect of the circuit is the provision of a two-level preset arrangement which presets the output node of the circuit to predetermined values before the input signals are applied.
    Type: Grant
    Filed: February 8, 1995
    Date of Patent: March 26, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Hiraishi, Takashi Akioka, Yutaka Kobayashi, Yuji Yokoyama, Masahiro Iwamura, Tatsumi Yamauchi, Shigeru Takahashi, Hideaki Uchida, Akira Ide
  • Patent number: 5398318
    Abstract: An improved buffer circuit arrangement is provided which is particularly useful for semiconductor integrated circuit semiconductor memories and microprocessors. The buffer circuit is capable of switching large loads in various types of LSIs, and features a low noise and high speed circuit operation. This is accomplished by a parallel connection of output transistors in an output buffer circuit, and by differentiating the starting time of operation between the output transistors connected in parallel without using a delay circuit. For example, differentiating the starting times can be achieved by either providing the transistors with different characteristics from one another or the driving circuits with different characteristics from one another. Another aspect of the circuit is the provision of a two-level preset arrangement which presets the output node of the circuit to predetermined values before the input signals are applied.
    Type: Grant
    Filed: November 2, 1990
    Date of Patent: March 14, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Atsushi Hiraishi, Takashi Akioka, Yutaka Kobayashi, Yuji Yokoyama, Masahiro Iwamura, Tatsumi Yamauchi, Shigeru Takahashi, Hideaki Uchida, Akira Ide
  • Patent number: 5387827
    Abstract: A semiconductor integrated logic circuit is provided which includes a plurality of logic gates each having a first input terminal for respectively receiving first input signals, wherein each of the logic gates is coupled to a common node. In one embodiment, first and second switching elements are also coupled to the common node. The first and second switching elements are both coupled to a second input terminal for receiving a second input signal which is common to the plurality of logic gates, and both operate complementary to one another in response to the second input signal. This arrangement is particularly effective for decoders in semiconductor memory circuits which use a common NMOS to receive one input for a plurality of logic decoder gates. An improved read/write arrangement is also provided for semiconductor memory circuits which includes circuitry to prevent connection of a common read line to the data lines during the writing operation.
    Type: Grant
    Filed: January 22, 1991
    Date of Patent: February 7, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Yuji Yokoyama, Takashi Akioka, Masahiro Iwamura, Atsushi Hiraishi, Yutaka Kobayashi, Tatsumi Yamauchi, Shigeru Takahashi, Nobuyuki Gotou, Akira Ide
  • Patent number: 5304868
    Abstract: A non-inverting buffer circuit device suited for an input buffer circuit of a semiconductor memory is provided so that the number of logic gate stages can be reduced to realize a high speed operation. The circuit is designed in such a way that an MOS transistor at an input stage drives a bipolar transistor at an output stage to produce an output. An n-channel MOS transistor and a p-channel MOS transistor connected in parallel between the base and the collector of the bipolar transistor are on/off controlled by an inverted signal of the input digital signal and a non-inverted signal thereof, respectively. In another aspect, the input buffer circuit includes an inverted signal outputting circuit, and a non-inverted signal outputting circuit in the set mode the input signal in the non-inverted state and outputting in the reset mode the signal at the prescribed potential.
    Type: Grant
    Filed: October 29, 1991
    Date of Patent: April 19, 1994
    Assignees: Hitachi, Ltd., Hitachi VLSI Engineering Corp.
    Inventors: Yuji Yokoyama, Kazuyuki Miyazawa, Hitoshi Miwa, Shoji Wada
  • Patent number: 5091883
    Abstract: An input buffer for processing an external signal is provided in one of passways, which is the most closest to a line for equally dividing the whole of a plurality of memory cell blocks longitudinally or laterally into two sections, the passway interposing between the adjacent memory cell blocks of the plurality of memory cell blocks to which a processed signal of the input buffer is transmitted, whereby the length of the signal pass from the input buffer to each memory cell of the memory cell blocks can be shortened. Therefore, since the memory cell or a logic element existing between the input buffer and the memory cell is operated by a pulse of little distortion without delay of time, a access time can be reduced and a processing speed of a microprocessor can be increased. Further, a degree of freedom in designing a system of a memory or the microprocessor is further improved.
    Type: Grant
    Filed: July 13, 1990
    Date of Patent: February 25, 1992
    Assignee: Hitachi, Ltd.
    Inventors: Nozomu Matsuzaki, Takashi Akioka, Masahiro Iwamura, Atushi Hiraishi, Tatsumi Yamauchi, Yuji Yokoyama, Yutaka Kobayashi, Hideaki Uchida
  • Patent number: 4285872
    Abstract: Glycidyl methacrylate or glycidyl acrylate is produced by reacting methyl methacrylate or methyl acrylate with glycide in the presence of a metal salt of a fatty acid.
    Type: Grant
    Filed: August 1, 1979
    Date of Patent: August 25, 1981
    Assignee: Nippon Oil and Fats Company, Ltd.
    Inventors: Rippei Tanabe, Yuji Yokoyama, Jiro Hirano