JPH0610251Y2 - Rotation angle detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of Invention] (Industrial field of application) The present invention relates to a rotation angle detector used for, for example, a dither rotation vibration detection monitor of a dither bias type ring laser gyro.

(Prior Art) Generally, a ring laser gyro has a dead zone in a low rotation speed region called a lock-in region. In order to reduce the lock-in area, there are a method of applying a constant angular velocity as a bias, a method of applying a bias to both-direction light by using a Faraday element, and the like. There is a dither bias method as a method for reducing the area. A ring laser gyro by this dither bias method is shown in FIG.

In FIG. 4, the ring laser block 11 is an optical closed circuit 12
And a plurality of mirrors 13. In this configuration, the ring laser block 11 and the light closing circuit 12 are slightly rotationally vibrated (dithered) around the central axis 15 perpendicular to the surface of the light closing circuit 12 to shorten the lock-in area passage time and reduce the influence. Is the dither bias method. At this time,
As shown in the figure, it is considered that the ring-shaped leaf spring 14 is placed at the center of the ring laser block 11 and driven by a piezoelectric element or the like to cause the ring laser block 11 to resonate. That is, since the dither vibration is detected as an output angular velocity pulse from the ring laser gyro, if the frequency and level of the vibration are known, the dither vibration component can be erased by a filter or the like in an electric circuit, and the true input angular velocity can be known. it can.

However, a filter generally has a long processing speed and is not suitable for practical use. Further, in a resonance system including the leaf spring 14, the ring laser block 11 and the like, there are problems that the resonance characteristics of the assembled ones generally vary, and further the resonance characteristics change depending on time and environment. Therefore, it is necessary to accurately monitor the vibration characteristics, peaks, frequencies, waveforms, phases, etc., so that the dither bias does not affect the accuracy of angular velocity detection of the ring laser gyro.

(Problems to be Solved by the Invention) As described above, in the ring laser gyro by the dither bias method, it is necessary to accurately monitor the dither vibration.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a rotation angle detector capable of monitoring an accurate waveform of dither vibration without adversely affecting an optical closed circuit.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a ring laser block in which an optical closed circuit is arranged in a small area around a vertical central axis in the optical closed circuit plane. A rotation angle detector that is used in a ring laser gyro that rotationally oscillates to shorten the lock-in area transit time, and that electrically detects the angle change of the optical closed circuit due to the rotational vibration. A permanent magnet fixed apart from the central axis, a winding coil fixed to a stationary portion so as to face the permanent magnet, and a magnetic flux of the permanent magnet does not affect the laser light in the ring laser block. Thus, the shield means for shielding the magnetic flux is provided, and the induced electromotive force generated in the winding coil is used as the detection signal.

(Operation) In the rotation angle detector having the above configuration, the permanent magnet is arranged on the side portion of the ring laser block while being separated from the rotation center axis.
An electromagnetic coil type sensor is configured by arranging the winding coil facing this, and the induced electromotive force generated in the winding coil by minute vibration is taken out as a detection signal.
Further, the magnetic flux of the permanent magnet is shielded to reduce the magneto-optical effect on the laser light.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the configuration when the present invention is applied to the gyro shown in FIG.
A rod-shaped permanent magnet 18 is attached to a side portion of the through a support 17. The permanent magnet 18 is loosely fitted in a cylindrical winding coil 19. The winding coil 19 is fixed to a non-moving part (for example, a gyro case) 21 through a support tool 20.

That is, the permanent magnet 18 fixed to the ring laser block 11 by the support 17 vibrates dither together with the ring laser block 11. Although this dither vibration is rotational vibration, its amplitude is usually as small as 1 to 5 minutes, and the error in the portion apart from the central axis 15 is so small that it can be ignored even if it is approximated to linear vibration. Therefore, the permanent magnet 18 is connected to the winding coil 19
Vibrate in. Then, the magnetic field near the winding coil 19 changes, and an induced electromotive force is generated in the coil 19. This induced electromotive force is essentially proportional to the vibration linear velocity of the permanent magnet 18, that is, the vibration angular velocity of dither vibration. Therefore, the output voltage 90 ° phase-shifted represents the dither vibration rotation angle of the ring laser block 11.

Since such an electromagnetic coil type sensor has no response delay, no hysteresis, and no electric bias, it is possible to monitor the characteristics of dither vibration with extremely high accuracy. Also, the output processing circuit is simple and the change in accuracy is small. Since the permanent magnet 18 is attached to the vibrating side, it is structurally more rigid than vibrating the winding coil 19,
Wiring is also easy. The permanent magnet 18 may be a permanent magnet alone, or may be a combination of a permanent magnet and a magnetic material.

FIG. 2 shows a further improvement of the device shown in FIG. 1, in which a magnet case 23 is fixed to the ring laser block 11 by a support 22. This magnet case
23 is made of a magnetic material, and is a permanent magnet 18 protruding inside.
It has a shielding effect that does not leak the magnetic flux from the outside of the magnet case 23. As a result, the magneto-optical effect on the laser light in the ring laser block 11 can be reduced.

FIG. 3 shows an improved version of the apparatus of FIG. 1 on the winding coil 19 side, in which a support base 24 fixed to the immovable portion 21 and a support 25 fixing the winding coil 19 are slid on each other. It is designed to be flexible and can be fixed in an appropriate position and easily removed. This facilitates the position adjustment of the permanent magnet 18 and the winding coil 19 and the attachment / detachment at the time of repair.

[Effect of the Invention] As described above, according to the present invention, it is possible to provide the rotation angle detector capable of monitoring the accurate waveform of the dither vibration without adversely affecting the optical closed circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a rotation angle detector according to the present invention, FIGS. 2 and 3 are configuration diagrams in which the apparatus of FIG. 1 is improved, and FIG. 4 is a conventional rotation angle detection device. It is a block diagram which shows the structure of a container. 11 …… Ring laser block, 12 …… Optical closed circuit, 13 ……
Mirror, 14 …… Leaf spring, 15 …… Center axis, 17,2
0,22,25 …… Supporting tool, 18 …… Permanent magnet, 19 …… Winding coil, 21 …… Fixed part, 23 …… Magnet case, 24 …… Supporting base.

Claims (1)

[Scope of utility model registration request] 1. A ring laser gyro for shortening a lock-in area transit time by vibrating a ring laser block provided with an optical closed circuit by a minute rotational oscillation around a vertical central axis in the surface of the optical closed circuit. In a rotation angle detector that electrically detects an angle change of an optical closed circuit due to rotation vibration, a permanent magnet fixed to a side portion of the ring laser block away from the central axis, and a permanent magnet facing the permanent magnet. A winding coil fixed to an immovable portion, and a shield means for shielding the magnetic flux of the permanent magnet so that the magnetic flux of the permanent magnet does not affect the laser light in the ring laser block. A rotation angle detector that uses induced electromotive force as a detection signal.