Patents Assigned to LITEF GmbH
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Patent number: 7231823Abstract: In a method for electronic tuning of the frequency of the read oscillation to the frequency of the stimulation oscillation in a Coriolis gyro, the resonator of the Coriolis gyro has a disturbance force applied to it such that the stimulation oscillation remains essentially uninfluenced. The read oscillation is changed so that a read signal that represents the read oscillation contains a corresponding disturbance component. The frequency of the read oscillation is controlled so that the phase shift between the disturbance signal and the disturbance component contained in the read signal is a minimum.Type: GrantFiled: October 8, 2003Date of Patent: June 19, 2007Assignee: LITEF GmbHInventor: Werner Schroeder
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Patent number: 7216525Abstract: A method for compensation of the zero error of a Coriolis gyro. The frequency of the read oscillation is modulated. The output signal from a rotation rate control loop or quadrature control loop for the Coriolis gyro is demodulated in synchronism with the modulation of the frequency of the read oscillation to obtain an auxiliary signal. The auxiliary signal is a measure of the zero error. A compensation signal is produced and passed to the input of the rotation rate control loop or quadrature control loop, with the compensation signal being controlled such that the magnitude of the auxiliary signal is as small as possible.Type: GrantFiled: March 26, 2004Date of Patent: May 15, 2007Assignee: LITEF GmbHInventor: Werner Schroeder
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Patent number: 7190463Abstract: The method according to the invention for preventing bias errors as a result of synchronous interference in fiber-optic gyroscopes (FOGs) provides for an additional signal ?E, which is periodical at the sampling clock rate and corresponds, for example, to a synchronous interference signal input to be added in the form of additional modulation to the modulation signal for a phase modulator within an MIOC. The demodulated detector signal from the FOG is preferably then correlated with the additional modulation, that is to say which is multiplied by the additional modulation and is added to it. The added-up signal, which is dependent on the error matching, controls a VCO (12) which readjusts the operating frequency of the FOG until the correlation tends to zero. The method can be used not only for phase ramp modulation but also for FOGs which operates using a random phase modulation method.Type: GrantFiled: June 20, 2002Date of Patent: March 13, 2007Assignee: LITEF GmbHInventor: Guenter Spahlinger
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Patent number: 7173712Abstract: A method for increasing the long-term operational reliability of a fiber optic interferometer. Noise in a detector output signal is set to a desired value by correcting the detector light power. Detector light power is corrected by varying a light source current of a light source of the interferometer. A change in the light source power results. It is thereby possible to increase both the reliability and useful life of the interferometer.Type: GrantFiled: July 26, 2002Date of Patent: February 6, 2007Assignee: LITEF GmbHInventor: Manfred Keller
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Patent number: 7130744Abstract: In a GPS-supported inertial attitude and heading reference system equipped with a Kalman correction filter and a multiple axis fiber optic gyroscope, the invention provides for only that scale factor error which is determined for the measurement axis (e.g. the vertical axis) with relatively fast motion dynamics to be used as the Kalman filter correction value for the scale factor error correction for all the measurement axes of the FOG to determine and compensate for the scale factor error caused by changes in the wavelength of a common light source. The scale factor error correction is used only with a long time constant.Type: GrantFiled: July 18, 2003Date of Patent: October 31, 2006Assignee: LITEF GmbHInventor: Manfred Krings
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Patent number: 7119324Abstract: A highly stable broadband light source includes a semiconductor light source having a specific emission spectrum, an optical filter having a specific bandpass filtering function and a predetermined bandwidth and a coupling element, to which the light emissions of the semiconductor light source and of the optical filter are fed. The light emission of the broadband light source occurs at the output of the coupling element. The spectrum of the light emission of the broadband light source is composed of the emission spectrum of the semiconductor light source and the bandpass filtering function of the optical filter. The wavelength of the optical filter is temperature-stabilized so that the spectrum of light emission of the broadband light source is essentially determined solely by the filtering function of the optical filter.Type: GrantFiled: February 19, 2004Date of Patent: October 10, 2006Assignee: LITEF GmbHInventor: Sven Voigt
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Patent number: 7102757Abstract: A device for current measurement based on a fiber-optic in-line Sagnac interferometer includes a birefringence phase modulator for non-reciprocal phase modulation of two orthogonal polarization modes of a light beam passing through the interferometer. The phase modulator is a digital phase modulator that is directly digitally drivable to permit simplification of the corresponding signal processing or driving electronics unit.Type: GrantFiled: March 15, 2002Date of Patent: September 5, 2006Assignee: LITEF GmbHInventors: Gunter Spahlinger, Sven Voigt
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Patent number: 6863832Abstract: A method for producing a silicon torsion spring capable, for example, of reading the rotation rate in a microstructured torsion spring/mass system. The system that is produced achieves a low torsional stiffness compared to a relatively high transverse stiffness in the lateral and vertical directions. The method proceeds from a wafer or wafer composite and, upon suitable mask coverage, a spring with a V-shaped cross section is formed by anisotropic wet-chemical etching which preferably extends over the entire wafer thickness and is laterally delimited only by [111] planes. Two of the wafers or wafer composites prepared in this way are rotated through 180° and joined to one another oriented mirrorsymmetrically with respect to one another, so that overall the desired X-shaped cross section is formed.Type: GrantFiled: July 20, 2000Date of Patent: March 8, 2005Assignee: LITEF GmbHInventors: Maik Wiemer, Karla Hiller, Detlef Billep, Uwe Breng, Bruno Rvrko, Eberhard Handrich
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Patent number: 6760111Abstract: Apparatus and a method for compensating production or operationally-induced inaccuracies in the binary-weighted electrodes of a high-resolution digital phase modulator of, for example, a fiber optic gyroscope. Programmable correction values are employed to increase the accuracy of each binary-weighted planar electrode. In the invention, a less significant component of the binary drive signal, if appropriate after compensation in a low resolution digital-to-analog converter, is converted into an analog signal that is applied to a specific or a separate additional electrode of the digital phase modulator.Type: GrantFiled: October 4, 2000Date of Patent: July 6, 2004Assignee: Litef GmbHInventors: John G. Mark, Mauricio Ribes, Daniel A. Tazartes
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Patent number: 6707975Abstract: An optical fiber coil for a fiber-optic measuring device and a method for producing it. An opitcal fiber is applied to a winding body in a quadrupole winding pattern in directly successive winding layers such that the turns of the individual winding layers have, at irregular spacings, as large a number of crossover points as possible. The spacings between the individual turns in each winding layer are variable, but, on average, they correspond to approximately half the diameter of the optical fiber. The optical fiber coil is preferably applied to the winding body without the use of fixing and buffer means.Type: GrantFiled: March 11, 2002Date of Patent: March 16, 2004Assignee: LITEF GmbHInventors: Hanns J. Bueschelberger, Hans G. Mueller, Felix Ruh, Claus Voelker, Anja Weiner Ringwald née Weiner
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Patent number: 6691572Abstract: An accelerometer having a micromechanical pendulum, a capacitive pick off and a control loop reset by electrostatic forces and, in a time sequence, applies a resetting voltage between the pendulum and two electrodes spaced apart on opposite sides of the pendulum. The control loop is designed such that, firstly, no charge difference flows via the pendulum and a force of identical magnitude thus acts on both sides of the pendulum. Secondly, when a pendulum deflection occurs in response to a voltage difference, the time durations of the respectively applied voltage pulses are impeded in accordance with the acceleration. The simultaneous control of two components results in the control bias tending essentially to zero. The capability of temporarily switching to detection of the total charge as the control variable also allows control of the scale factor of the accelerometer.Type: GrantFiled: December 27, 2001Date of Patent: February 17, 2004Assignee: Litef GmbHInventor: Eberhard Handrich
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Patent number: 6563587Abstract: In a fibre-optic Sagnac interferometer, in particular for determining rotational speeds (fibre gyro), having an optical directional coupler (3) which is located in the light path from a light source (1) and whose at least one output is connected via a spatial filter (6) and a polarization filter (7) to a beam splitter (8) which, on the one hand, splits the light transmitted by the polarization filter (7) into two component light beams which are irradiated into the two ends of an optical fibre (9), it being the case, on the other hand, that the component light beams returning after traversing the optical fibre (9) are reunited in an interfering fashion and applied to a light-sensitive receiver (5), it is provided for the purpose of reducing the amplitude error, that is to say, the polarization ratio of the light upstream of the polarization filter (7), to produce the spatial filter (6) from monomode fibre.Type: GrantFiled: July 27, 2000Date of Patent: May 13, 2003Assignee: Litef GmbHInventors: Hanns J. Bueschelberger, Manfred Kemmler
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Patent number: 6539799Abstract: A spin rate measurement device for rotating missiles. Preferably, three micromechanical spin rate sensors whose three spatial axes are aligned at right angles to one another, each of which is designed to be excited, read and reset capacitively, are arranged on a single platform that can be rotated by means of a servo loop for rotation decoupling. The spin rate measurement device is distinguished by high bias and scale factor stability that can be checked at any time.Type: GrantFiled: June 29, 2000Date of Patent: April 1, 2003Assignee: LITEF GmbHInventors: Eberhard Handrich, Hermann Hog
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Patent number: 6538746Abstract: A single laser is stabilized sequentially in time with respect to different wavelengths in conjunction with a continuous, preferably linear, wavelength transition for absolute optical interferometric measurement. During the wavelength transition, the number of the traversing interferences is counted in a measuring channel. The length of a measuring section may be measured in absolute terms to give known and stable wavelengths and phase measurements of the two wavelengths. Active integrated optics and residual phase measurement by compensation in the integrated optics make it possible to detect wavelength differences of 10−7 &lgr;.Type: GrantFiled: November 17, 2000Date of Patent: March 25, 2003Assignee: Litef GmbHInventor: Eberhard Handrich
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Patent number: 6490923Abstract: A micromechanical rotation rate sensor based on the Coriolis principle includes two plate-like oscillators arranged one above the other in two planes for excitation to oscillate by means of an electrostatic drive. Three elements in each case form an oscillator structure. The oscillators are in each case suspended on opposite side edges by at least one web between an associated plate-like support and an associated drive plate element. The two supports and the two drive plate elements are, in each case, arranged one above the other in layers. A fixed plate element is located between the two drive plate elements so that, in each case, an identical narrow drive gap is defined between the drive plate elements. The drive gap is considerably smaller than the distance between the plate-like oscillators.Type: GrantFiled: December 14, 2000Date of Patent: December 10, 2002Assignee: LITEF GmbHInventors: Uwe Breng, Martin Hafen, Eberhard Handrich, Bruno Ryrko
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Patent number: 6374671Abstract: For the drive excitation, the method for the capacitive drive excitation of oscillators in sensors for the capacitive measurement of force, acceleration and, in particular, rotation rates according to the Coriolis principle, provides according to the invention for the use of high-frequency constant-amplitude pulse packets with no DC component, the width or phase angle of which can be adjusted in order to keep the oscillator speed constant, for the purpose of resetting or correcting tolerances.Type: GrantFiled: October 26, 1999Date of Patent: April 23, 2002Assignee: Litef GmbHInventors: Bruno Ryrko, Günter Spahlinger, Walter Gutmann
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Patent number: 6373048Abstract: A method and apparatus for stabilizing the scale factor of a fiber optic gyroscope in which a superluminescence diode or broadband multimode laser comprises the light source. The emission bandwidth injected into a fiber end from the light source is limited to a considerably narrower transmission bandwidth within the wavelength band of the intensity characteristic of the light by a narrowband optical filter. The temperature at the filter is measured, and the transmission bandwidth quickly corrected by means of a pre-calibrated look-up table when optical interference filters are employed. The readjusted wavelength value is used for scale factor calculations.Type: GrantFiled: July 20, 2000Date of Patent: April 16, 2002Assignee: Litef GmbHInventor: Wolfgang Tschanun
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Patent number: 6321146Abstract: A sensor is provided on the vehicle of a driverless transport system. The sensor is based on the principle of a computer mouse for ascertaining either a drift angle &Dgr;&agr; or the transverse movement is detected as a path difference &Dgr;q whereby lateral drift due, for example, to roadway covering irregularities and to curves, is detected directly. A considerable improvement in the tracking accuracy of driverless transport vehicles is thereby provided.Type: GrantFiled: August 6, 1998Date of Patent: November 20, 2001Assignee: LITEF GmbHInventor: Jürgen Schnell
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Patent number: 6271789Abstract: A method for checking the reliability of nominal position findings on the basis of propagation time measurements. The method is characterized by the use of inertial systems to increase the measurement redundancy of the available measured values. The dimension of the measurement matrix of the nominal system is advantageously increased for such purpose. The method is primarily suitable for hybrid inertial/satellite navigation systems.Type: GrantFiled: January 5, 2000Date of Patent: August 7, 2001Assignee: Litef GmbHInventor: Jens Rainer Beerhold
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Patent number: 6231245Abstract: A connection between an optical waveguide and an encapsulated optical receiver having a window. An encapsulation-end end element of the waveguide is introduced into a capillary-like collar secured on top of the window which is provided in the encapsulation. The end element is bonded in the collar, which is surrounded by an anti-kink protective sleeve that overlaps the edge of the encapsulation and is preferably composed of one piece of a shrink-fit hose. The sleeve is filled on the inside with a sealing compound in the vicinity of the collar. The resulting connection is particularly resistant and insensitive to changes in temperature, moisture, vibration and shock.Type: GrantFiled: September 28, 1999Date of Patent: May 15, 2001Assignee: Litef GmbHInventors: Hanns J. Büschelberger, Antonio Pla' Ibanez