Patents by Inventor Fumio Nakajima

Fumio Nakajima 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: 4179671
    Abstract: A piezo-electric oscillator composed of a quartz crystal, an inverting amplifier connected across the quartz crystal, an output capacitor connected to an output side of the quartz crystal, and a plurality of input capacitors. The input capacitors are selectively coupled to the input side of the quartz crystal by means of an electronic switching means by which an output frequency of the quartz crystal is adjusted to a prescribed value.
    Type: Grant
    Filed: January 3, 1978
    Date of Patent: December 18, 1979
    Assignee: Citizen Watch Company Limited
    Inventors: Hirohiko Yoshida, Fumio Nakajima
  • Patent number: 4158287
    Abstract: An electro-mechanical transducer driver circuit for an electronic timepiece characterized in that the pulse width of a driving pulse which drives an electro-mechanical transducer is controlled in a step-wise manner by the induced voltage of a driving coil.
    Type: Grant
    Filed: August 3, 1977
    Date of Patent: June 19, 1979
    Assignee: Citizen Watch Company Limited
    Inventors: Fumio Nakajima, Takayasu Machida, Kenji Yamada
  • Patent number: 4150536
    Abstract: An electronic timepiece includes a reversible stepping motor to drive rotatable hands to provide a time display. In a first preferred embodiment, the electronic timepiece includes a circuit means to generate alternating current pulses having an increased pulse width or an increased amplitude to drive the stepping motor with an increased driving current during high speed time correction when a manually operable external control member is actuated during time correction.
    Type: Grant
    Filed: January 21, 1977
    Date of Patent: April 24, 1979
    Assignee: Citizen Watch Company Limited
    Inventors: Fumio Nakajima, Kenji Yamada, Takayasu Machida, Yasushi Nomura, Minoru Watanabe
  • Patent number: 4144467
    Abstract: A pulse motor for clockworks and the like in which the rotor comprises two spaced-apart permanent magnetic disks mounted upon a common shaft and rotatable with respect to a stator. The stator comprises a respective pair of magnetic poles in the plane of each disk, the poles of the pair being interconnected by a shank and a coil wound upon the respective shanks, the coils lying on opposite sides of the rotor. The coils can be excited independently to cause the respective pair of poles to magnetically cooperate with the respective disk and rotate the motor in the forward or the reverse sense.
    Type: Grant
    Filed: July 31, 1975
    Date of Patent: March 13, 1979
    Assignee: Citizen Watch Co., Ltd.
    Inventors: Fumio Nakajima, Akira Nikaido, Mitsuo Onda, Takayasu Machida, Takashi Toida
  • Patent number: 4129981
    Abstract: An electronic timepiece having a reversible stepping motor to actuate time-indicating hands to provide a time display, which comprises a driver circuit to produce driving current pulses composed of compound pulses appearing each time unit. A rotor of the stepping motor rotates a plurality of steps during each time unit to cause one of the time-indicating hands to advance through unequal intervals to provide a modulated display.
    Type: Grant
    Filed: February 2, 1977
    Date of Patent: December 19, 1978
    Assignee: Citizen Watch Company Limited
    Inventors: Yasushi Nomura, Fumio Nakajima, Kenji Yamada, Takayasu Machida
  • Patent number: 4066947
    Abstract: A stepping motor for use in an electronic timepiece in which a rotor is stable on an axis of static equilibrium at an angle from 0.degree. to 30.degree. with respect to a center line of the air gaps between stator pole pieces. The relationship between the stator pole pieces and the rotor is such that the phase difference between driving torque and attraction force applied to the rotor ranges from 60.degree. to 90.degree. by an electrical angle in a normal rotation of the rotor and ranges from 90.degree. to 120.degree. in a reverse rotation of the rotor.
    Type: Grant
    Filed: January 7, 1976
    Date of Patent: January 3, 1978
    Assignee: Citizen Watch Company Limited
    Inventors: Fumio Nakajima, Takayasu Machida, Kenji Yamada
  • Patent number: 4055785
    Abstract: A stepping motor for an electronic timepiece comprises a permanent magnet rotor, a stator and a driving coil, having at least one static equilibrium point for the rotor. The driving coil is arranged to be energized by a current smaller than a driving current so that the stator is energized to required polarities of low flux intensity, whereby the static equilibrium point for the rotor is electromagnetically shifted to an arbitrary position to permit rotation of the rotor in any desired direction.
    Type: Grant
    Filed: June 18, 1976
    Date of Patent: October 25, 1977
    Inventors: Fumio Nakajima, Takayasu Machida, Kenji Yamada
  • Patent number: 4048548
    Abstract: A stepping motor for use in an electronic timepiece which has a permanent magnet rotor and a stator provided with a driving coil. The stator is comprised of stator pole pieces each having assymetric portions which provide primary and secondary magnetic paths, respectively, whereby two static equilibrium positions are provided. The rotor may be stable at either one of these static equilibrium positions by controlling the supply of two-phase pulses to the driving coil so that the rotor may be rotated in normal or reverse direction. SuThis invention relates in general to stepping motors and, more particularly, to a reversible stepping motor for use in an electronic timepiece.As is well known, stepping motors, also called pulse motors, are becoming increasing employed in industrial applications due to the introduction of digital pulse techniques. Typical one of these applications involves electronic timepieces having electro-mechanical timekeeping movements which are driven by the stepping motors.
    Type: Grant
    Filed: December 24, 1975
    Date of Patent: September 13, 1977
    Assignee: Citizen Watch Company Limited
    Inventors: Fumio Nakajima, Takayasu Machida, Kenji Yamada
  • Patent number: 3958167
    Abstract: A reversible pulse-motor driving circuit comprising a steady driving circuit composed of an oscillator circuit, a frequency divider circuit, a waveform conversion circuit, and a driving circuit, and a fast correction driving-circuit composed of a fast correction set-circuit, a first gate circuit, a detector circuit, a normal and reverse discrimination circuit, a conversion change-over circuit, a pulse selector circuit, a first memory circuit, a second gate circuit and a second memory circuit, whereby a user can hear a time signal delivered from a calculation circuit and only push a pushbutton to rotate the pulse motor in a reverse direction when the second hand is ahead of the correct time, and rotate the pulse motor in a forward direction when the second hand is lagging with respect to the correct time, and the use of a frequency higher than the steady driving frequency permits a fast setting of the second, minute or hour hand to the correct time.
    Type: Grant
    Filed: November 30, 1973
    Date of Patent: May 18, 1976
    Assignee: Citizen Watch Co., Ltd.
    Inventors: Fumio Nakajima, Akira Nikaido, Mitsuo Onda, Takayasu Machida, Takashi Toida