Sumitomo Electric Industries, Limited

Akihiro Ooka

Yozo Nishiura

Takaki Iwashita

Yutaka Wada

Yasuhiko Nishi

Kazuo Hirano

Koji Satoh

Hayato Hasegawa

Noritaka Kuroda

Kenji Kawamura

Katsuaki Itoh

Conventional fiber-optic gyroscopes were provided with an independent photodetector for detecting interfering beams. The existence of the independent photodetector required two beam dividing-and-combining devices for equalizing the experiences of the clockwise-spreading beams and the counterclockwise-spreading beams. Curtailment of an expensive beam dividing-and-combining device is desirable for reducing the cost of gyroscopes. This invention dispenses with the independent photodetector. Instead of the independent photodetector, the light source itself or the monitoring photodiode detects the interfering beams by the change of driving current, applied voltage or photocurrent. Elimination of the independent photodetector saves one beam dividing-and-combining device by equalizing the path of the progressing beams to the path of the regressing beams. Optimum light sources, interposition of polarizer, position of depolarizer and use of birefringent material as polarizer are explained.

Fiber-optic gyroscope obtaining a signal from a perturbed light source

An optical fiber type polarizer comprises a first optical fiber constituted by a birefringent optical fiber wound at a predetermined winding radius and having winding start and end fixed to each other by an adhesive, the first optical fiber having short extra portions respectively extending from the winding start and end, and the length of each of the short extra porions being at least as small as the predetermined winding radius. The optical fiber type polarizer further comprises a second optical fiber spliced to one of the short extra portions of the first optical fiber, and a third optical fiber spliced to the other of the short extra portions of the first optical fiber.

Optical fiber type polarizer

In a locator for location and direction detections of moving bodies which employs, in the direction detection, a magnetic direction sensor for outputting direction data and a gyro for outputting angular speed data, the locator for location and direction detections of moving bodies comprising a normal judgement function for the magnetic direction sensor which compares a direction variation quantity within an assigned time which is obtained from the difference of the direction data of the magnetic direction sensor, and an angle variation quantity within the assigned time which is obtained from an integral value of the angular speed data of the gyro, and in the case that the difference between the compared quantities is over a first predetermined value, judges that an error has occurred in the direction data of the magnetic direction sensor. After judgement of an occurrence of the error and when the difference between the direction variation quantity and the angle variation quantity is below a second predetermined value, it is judged that the direction data of the magnetic direction sensor has returned to normalcy.

Locator for a moving body

A method of correcting a zero point of a gyro, comprises the steps of detecting a speed of a moving body and outputting a speed signal corresponding to the speed; determining with the speed signal whether the moving body is at a stopping condition; computing an average value of output values of the gyro within a constant time in which the moving body is at the stopping condition, and setting the average value to a new zero point of the gyro; and correcting an output value of the gyro with the new zero point. An apparatus for correcting a zero point of a gyro, comprises a speed sensor for detecting a speed of a moving body and outputting a speed pulse signal corresponding to the speed; a flip-flop circuit which is set by the speed pulse signal of the speed sensor; and a zero-point correcting circuit wherein it is determined with a level of an output of the flip-flop circuit and with an output of a timer whether the moving body is at a stopping condition and wherein a zero point of the gyro is corrected with an average value of outputs of the gyro at the same time the moving body is at the stopping condition, the zero point correcting circuit outputting a clear signal to the flip-flop circuit, the flip-flop circuit being cleared by the clear signal and then set by the speed pulse signal.

Method of correcting zero point of gyro and apparatus therefor

An apparatus for recognizing a character (including an alpha-numeric character, mark or other character) written using a stylus applied to a tablet which stylus and tablet include an arrangement for providing an indication of position of the stylus with respect to a surface of the tablet. The character recognition apparatus determines the length and gradient (slope) of line segments of strokes drawn by a user which strokes combine to form characters. After determining length and gradient of a line segment, there is assigned to the line segment a distinctive code. A particular character is determined by examining the order of codes which define particular combinations of strokes. Recognition of characters is carried out in substantially real time.

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Osaka, Japan

Akihiro Ooka