COMPENSATING ACCELEROMETER WITH OPTICAL ANGLE SENSING

Abstract

A compensating accelerometer includes a housing, and a sensing element mounted in the housing. The sensing element includes a pendulum flexibly mounted on a base. The sensing element includes a coil mounted on a movable plate, a curtain having a slit, and a load mass affixed to the curtain. An angle sensor within the housing includes the curtain, a fork, a light source and a differential light detector. A momentum sensor within the housing includes a permanent magnet, an inner magnetic conductor, an outer magnetic conductor and the coil. The permanent magnet is magnetized in a direction of an axis of the pendulum. A stopper is used to adjust position of the fork. A spring is on opposite side of the fork, for taking up slack in the fork. A fixator has an eccentric, for adjusting a gap between the curtain and the light detector.

Description

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 illustrates a cross-sectional view of the accelerometer of one embodiment of the invention, with the view shown along the sensitivity axis SA and pendulum axis PA.

FIG. 2 shows the view in the direction of arrow A in FIG. 1, with element 21 removed.

FIG. 3 shows the view in the direction of arrow B in FIG. 1, with element 21 removed.

FIGS. 4A and 4B illustrate the sensing element.

FIG. 5 illustrates a functional electrical circuit diagram of the accelerometer.

FIGS. 6A and 6B illustrates the principle of operation of the sensing element of the exemplary accelerometer of FIG. 1.

FIG. 7 illustrates the differences between the described accelerometer and conventional accelerometers.

Claims

1. A compensating accelerometer comprising: a housing;a pendulum within the housing flexibly coupled to a base,wherein the pendulum includes a coil mounted on a movable plate and a curtain having an opening;a light source and a differential light detector generating a signal proportional to angular displacement of the pendulum;a magnet magnetized in a direction of an axis of the pendulum;a magnetic conductor that, together with the coil and the magnet, is used to return the pendulum to a neutral position;a feedback circuit generating an output proportional to acceleration experienced by the compensating accelerometer based on the angular displacement of the pendulum.

2. The accelerometer of claim 1, wherein the fork, the curtain, the light source and the differential light detector form an angle sensor of angular displacement of the pendulum.

3. The accelerometer of claim 2, further comprising a stopper that adjusts position of the fork.

4. The accelerometer of claim 3, further comprising springs on opposite sides of the fork, for taking up slack in the fork.

5. The accelerometer of claim 3, further comprising a fixator that has an eccentric, for adjusting a gap between the curtain and the light detector.

6. The accelerometer of claim 2, wherein the fork is movable along a measurement axis of the accelerometer using guides, and is fixed in place using screws.

7. The accelerometer of claim 6, further comprising a stopper whose position can be adjusted in a threaded opening and which contacts the fork for fixing the fork in place.

8. The accelerometer of claim 7, further comprising a spring for taking up slack in a position of the fork, the spring positioned between the fork and a flange.

9. The accelerometer of claim 7, wherein the accelerometer is tuned mechanically by adjusting the stopper's position.

10. The accelerometer of claim 1, wherein the magnet is a permanent magnet.

11. The accelerometer of claim 1, wherein the opening is shaped as a slit.

12. The accelerometer of claim 1, further comprising a load mass affixed to the curtain.

13. The accelerometer of claim 1, wherein the movable plate has a thin portion to enable deflection of the plate.

14. The accelerometer of claim 1, wherein the magnetic conductor includes an inner magnetic conductor and an outer magnetic conductor.

15. The accelerometer of claim 1, wherein a differential light detector and a light source are fixed relative to the housing.

16. The accelerometer of claim 1, wherein the magnet, the magnetic conductor and the coil form a momentum sensor.

17. The accelerometer of claim 1, wherein an axis of suspension of the pendulum substantially coincides with a neutral plane of the magnet.

18. The accelerometer of claim 1, wherein the feedback in the angle sensor circuit compensates for temperature effects.