JPH04178520A - Optical fiber gyro - Google Patents

Abstract

PURPOSE:To maintain high detecting precision with high resolution even during input of a low angular velocity by feeding light from a single light source to a coil for precise detection and a coil for coarse detection and providing a wide dynamic range. CONSTITUTION:A photo switch 10 and a signal processing circuit 13 are switched by means of a selection signal 14a from a system selecting circuit part 14, and a detecting system employing a sensing coil 6A and a detecting system employing a sensing coil 6 can be selected. The coil 6A is for high sensitivity precise detection of a plurality of the numbers of turns and the coil 6 is for low sensitivity coarse detection of the number of turns lower than that of the 6A. Thus, the switch 10 is switched by means of the selection signal 14a, even both systems of the sensing coils 6 and 6A can be detected by a detector 7 and both of a high angular velocity and a low angular velocity can be detected with high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention relates to an optical fiber gyro, and particularly to the use of a first sensing coil for precise detection and a second sensing coil for rough detection. This invention relates to novel improvements for widening dynamic range and achieving low power consumption.

b. Prior Art There are various types of optical fiber gyros that have been used in the past, but the most typical one is the generally adopted configuration shown in Figures 2 and 3. can be mentioned.

That is, what is indicated by the reference numeral 1 in FIG. 2 is a light source consisting of a laser beam, and the light 1 from this laser beam 1 is
a represents the first coupler 2, polarizer 3, and second coupler 4;
After passing through the modulator 5 and being modulated, the light enters the sensing coil 6.

The light 1a that has entered the sensing coil 6 is again
It is configured so that the light is received by the detector 7 via the second coupler 4, the polarizer 3, and the first coupler 2, and the interference phase difference of light when the angular velocity is input (well-known Sagnac phase difference)
is detected by the signal processing circuit section 8.

C9 Problems to be Solved by the Invention Since the conventional optical fiber gyro was configured as described above, the following problems existed.

That is, in the case of the detection method based on the optical interference phase difference of the phase modulation method described above, as shown by the relationship between the input angular velocity and the optical system detection range shown in FIG. 3, the Sagnac phase difference is +7 to -7 By design, the Sagnac phase difference corresponds one-to-one in proportion to the input angular velocity, so the dynamic range is limited, and in the case of a configuration using one sensing coil, the In the case of angular velocity, the resolution was limited by noise and other factors.

The present invention has been made to solve the above-mentioned problems, and in particular, by using a first sensing coil for precise detection and a second sensing coil for coarse detection, the dynamic range is widened, Another object of the present invention is to obtain an optical fiber gyro that achieves low power consumption.

d Means for Solving the Problems The optical fiber gyro according to the present invention guides a light source to a sensing coil made of an optical fiber, and converts the optical interference phase difference at the time of angular velocity input into a signal processing circuit. In the optical fiber gyro, the sensing coil is used as a first section for precise detection.
It is composed of a sink coil and a second sensing coil for rough detection, and supplies light from one of the light sources via an optical switch, and supplies light from each of the sensing coils to one of the sensing coils via the optical switch. This configuration allows selective input to the detector.

e. Function In the optical fiber gyro according to the present invention, the light emitted from one light source is connected to the first one for precise detection by the coupler.
Since the power is supplied to the sensing coil and the second sensing coil for rough detection, the first sensing coil with a plurality of turns performs highly sensitive and precise detection, and the second sensing coil with a smaller number of turns than the first sensing coil performs fine detection. Since the sensing coil performs rough detection of low 5 degrees, a wide dynamic range can be obtained by switching each sensing coil even for high-speed and low-speed input angular velocities. In addition, by controlling the entry and exit of light into and out of each sensing coil using an optical switch, selective detection can be performed using one detector.

f. Embodiments Hereinafter, preferred embodiments of the optical fiber gyro according to the present invention will be described in detail with reference to the drawings. In addition, the same as the conventional example
Or equivalent parts will be explained using the same reference numerals.

FIG. 1 is a block diagram showing an optical fiber gyro according to the present invention.

What is indicated by the reference numeral 1 in the figure is a light source made of laser light, and the light 1a from this light source 1 is transmitted to the first coupler 2.
, polarizer 3, optical switch 10 and second coupler 11
from the first sensing coil 6A via the first modulator 5A.
is supplied to.

A second sensing coil 6 is connected to the optical switch 10 via a third coupler 12 and a second modulator 5, and the return light from each sensing coil 6.6A is again connected to the single light beam. It is configured to return to switch 10.

The first coupler 2 is provided with one detector 7, and this detector 7 includes a signal processing circuit section 13 for detecting angular velocity using the well-known optical interference phase difference. It is connected.

A system selection circuit section 14 is connected to the optical switch 10 and the signal processing circuit section 13, and the optical switch 10 and the signal processing circuit section 13 are switched by a selection signal 14a from the system selection circuit section 14. It is configured such that either a detection system using the first sensing coil 6A or a detection system using the second sensing coil 6 can be selectively used.

The first sensing coil 6A has a plurality of turns and is configured for high-sensitivity precision detection, and the second sensing coil 6 has a low-sensitivity coarse detection with a smaller number of turns than the first sensing coil 6A. Configured for detection.

Therefore, in the above-described configuration, by switching the optical switch 10 using the selection signal 14a of the system selection circuit section 14, the detector 7 can detect any system of the first sensing coil 6A and the second sensing coil 6. ,
Both high and low angular velocities can be detected with high resolution.

g Effects of the Invention Since the optical fiber gyro according to the present invention is configured as described above, the following effects can be obtained.

In other words, the light from one light source is supplied to the first sensing coil for precise detection and the second sensing coil for coarse detection to obtain a wide dynamic range, allowing detection with high resolution even when inputting low angular velocity. and maintain high accuracy.

Furthermore, since light from one light source is supplied to two systems of sensing coils, a configuration with low power consumption can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical fiber gyro according to the present invention, FIG. 2 is a block diagram of a conventional optical fiber gyro, and FIG. 3 is a characteristic diagram showing an optical system detection range. 1 is a light source, 1a is a light, 2 is a first coupler, 6A is a first sensing coil, 6 is a second sensing coil, 13 is a signal processing circuit section, and 10 is an optical switch. Figure 1 (13) shows the output characteristics after A-phase modulation of the word processing circuit.

Claims (1)

[Claims] Light (1a) from a light source (1) is guided to a sensing coil (6, 6A) made of an optical fiber, and a signal processing circuit (13) detects the interference phase difference of the light when angular velocity is input. In the optical fiber gyro, the sensing coil (6, 6A) is composed of a first sensing coil (6A) for precise detection and a second sensing coil (6) for rough detection, Light (1a) from one of the light sources (1) is supplied via an optical switch (10), and one light from each of the sensing coils (6, 6A) is supplied via the optical switch (10). An optical fiber gyro characterized in that input is selectively input to a detector (7).