Patents Assigned to Nohken Inc.
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Patent number: 7479921Abstract: A transmission unit emits an electromagnetic wave having the same frequency f as an output signal from a sending unit in a direction of a measurement axis. A detecting unit performs synchronous detection on a reflected wave detected by a directional coupler by an in-phase signal and a quadrature signal of the transmission signal, and by extracting DC component from the detection signal, detects the in-phase component and quadrature component of the reflected wave. An analysis signal generating unit mixes the in-phase component and quadrature component of the reflected wave and signals having periodicity corresponding to a prescribed distance, and using only one of the resulting side bands, generates an analysis signal. Fourier transform unit finds distance to the object of measurement from a profile obtained by Fourier transform of the analysis signal.Type: GrantFiled: July 14, 2006Date of Patent: January 20, 2009Assignees: The University of Tokushima, Nohken Inc.Inventors: Tadamitsu Iritani, Kazuhiro Wakabayashi
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Patent number: 6922065Abstract: A triangular wave generating circuit (21) generates a sweep voltage of a triangular wave, a VCO (22) generates a sweep of a frequency according to the sweep voltage, and a driving coil (4) is driven by the sweep voltage. From the current flowing through the driving coil (4), an interference component is extracted and rectified by a rectifier circuit (27). A peak hold circuit (28) holds a peak value of an interference voltage within a period corresponding to one sweep. The peak value thus held is compared by a comparator circuit (29) with a predetermined value and accordingly, a relay circuit (30) outputs a signal indicative of whether an object is present or not.Type: GrantFiled: May 2, 2002Date of Patent: July 26, 2005Assignee: Nohken Inc.Inventor: Hiroshi Kawakatsu
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Patent number: 6769804Abstract: A magnet is provided to a vibrating plate within a detection pipe unit and an electromagnet is placed opposite to the magnet with a slight gap therebetween. A drive circuit applies, to a coil at every predetermined measurement cycle, an alternating current at a frequency which is swept over a predetermined range centered at a resonance frequency of the vibrating plate. When the alternating current is applied, a phase comparison circuit detects a change in phase that is caused according to whether or not an object contacts the vibrating plate. A microcomputer determines presence/absence of the object based on the detected change in phase, measures the temperature based on the detected change in phase in a former half cycle of the predetermined measurement cycle and changes the swept frequency based on the result of measurement of the temperature in a latter half cycle of the predetermined cycle.Type: GrantFiled: June 16, 2003Date of Patent: August 3, 2004Assignee: Nohken Inc.Inventor: Hiroshi Kawakatsu
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Publication number: 20030235233Abstract: A magnet is provided to a vibrating plate within a detection pipe unit and an electromagnet is placed opposite to the magnet with a slight gap therebetween. A drive circuit applies, to a coil at every predetermined measurement cycle, an alternating current at a frequency which is swept over a predetermined range centered at a resonance frequency of the vibrating plate. When the alternating current is applied, a phase comparison circuit detects a change in phase that is caused according to whether or not an object contacts the vibrating plate. A microcomputer determines presence/absence of the object based on the detected change in phase, measures the temperature based on the detected change in phase in a former half cycle of the predetermined measurement cycle and changes the swept frequency based on the result of measurement of the temperature in a latter half cycle of the predetermined cycle.Type: ApplicationFiled: June 16, 2003Publication date: December 25, 2003Applicant: NOHKEN INC.Inventor: Hiroshi Kawakatsu
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Patent number: 6292104Abstract: From the time of power on, an output of a variable frequency generating circuit is kept matching with the resonance frequency of a resonance circuit. When an object of detection comes into contact or to the vicinity of a detection electrode and the resonance frequency of resonance circuit changes, a phase deviation is generated from the output of the variable frequency generating circuit. The deviation is detected by a phase comparing circuit, and a control circuit changes a control voltage so that the oscillation frequency of variable frequency generating circuit is changed to attain phase matching. This change is detected by a detection circuit, and presence/absence of the object is detected.Type: GrantFiled: July 14, 2000Date of Patent: September 18, 2001Assignee: Nohken Inc.Inventor: Kazuhiro Wakabayashi
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Patent number: 6105425Abstract: A base of a detection pipe is fixed. A vibration piece has its one end fixed to a closing portion and the other end provided with a permanent magnet. An electromagnet is closely attached inside the detection pipe such that it is arranged in a direction of axis of the permanent magnet, thereby forming a folded cantilever. Vibration is detected by a distortion detecting element, and the output therefrom is amplified by an amplification circuit for driving the electromagnet. Thus, the detection pipe, closing portion and vibration piece are repeatedly vibrated.Type: GrantFiled: February 16, 1999Date of Patent: August 22, 2000Assignee: Nohken Inc.Inventor: Hiroshi Kawakatsu
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Patent number: 6101873Abstract: Switching member SW20 which receives detection signals for detecting capacitance outputted from a control part 35, controls each of switches so as to measure capacitance between electrodes positioned adjacently (an electrode TE1 and an electrode TE2, and so on) before measuring capacitance of measuring object. Capacitance initially measured between the adjacent electrodes are stored in a storing circuit 30. The initial capacitance are averaged to calculate an averaged initial value. Upon calculating the averaged initial value, correction values which represent difference between the averaged initial value and the initial capacitance are calculated. Actual measured values are corrected using the correction values when level of measuring object is measured. It is therefore possible to measure level of measuring object without influence of floating items or the like with stability, because level measurement is conducted by utilizing capacitance measured between adjacent electrodes.Type: GrantFiled: May 17, 1996Date of Patent: August 15, 2000Assignee: Nohken Inc.Inventors: Hiroshi Kawakatsu, Kouichi Tanaka, Hiroshi Uematsu
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Patent number: 5247832Abstract: In a vibrator-type level sensor, a detection pipe (14) is provided projecting from a base unit (1) to be mounted to a wall of a container (8) containing a substance (100) to be detected. The detection pipe (14) has an internal vibration plate (12) attached with a vibrating piezo-electric device (16) thereon and the internal vibration plate (12) is mechanically connected through an end cap (13) to the free end of the detection pipe (14, 140) to form a folded cantilever unit (30) which responds when the end cap (13) or pipe (14) are contacted by the material being sensed in the container.Type: GrantFiled: February 14, 1992Date of Patent: September 28, 1993Assignee: Nohken Inc.Inventors: Takayuki Umezawa, Takao Kawakita
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Patent number: 4740726Abstract: A vibrator-type level sensor having a detecting pipe (20) in which an inner vibration member (22) with piezo-electric devices (8a) (8b) (8c) is mounted, the detecting pipe (20) and the inner vibration member (22) constituting a folded cantilever.Type: GrantFiled: July 21, 1986Date of Patent: April 26, 1988Assignee: Nohken Inc.Inventor: Takayuki Umezawa