Capacitive acceleration sensor
View Patent ↗The invention relates to measuring devices used for the measuring of acceleration, and specifically to capacitive acceleration sensors. The capacitive acceleration sensor according to the present invention comprises a pair of electrodes composed of a movable electrode ( 4 ) and a stationary electrode ( 5 ), and, related to the pair of electrodes, an isolator protrusion having a special coating. The invention provides an improved, more durable sensor structure, which withstands wear caused by overload situations better than earlier structures.
1. A capacitive acceleration sensor comprising at least one pair of electrodes, such that the pair of electrodes comprises a movable electrode responsive to the acceleration, at least one stationary electrode, and at least one isolator protrusion, wherein the isolator protrusion being coated with a diamond-like DLC coating, comprises a two-layer composite structure with a base layer that consists of oxide and the base layer is coated with a top layer of the diamond-like DLC coating.
2. The capacitive acceleration sensor of claim 1 , wherein the diamond-like DLC coating of the top layer extends also onto the sides of the isolator protrusion.
3. The capacitive acceleration sensor of claim 2 , wherein the diamond-like DLC coating of the top layer also extends beyond the edges of the isolator protrusion onto the area of the stationary electrode.
4. The capacitive acceleration sensor of claim 1 , wherein the base layer is essentially thicker than the top layer.
5. The capacitive acceleration sensor of claim 1 , wherein the pair of electrodes of the acceleration sensor comprises several isolator protrusions.
6. The capacitive acceleration sensor of claim 1 , wherein the isolator protrusions are positioned on both sides of the movable electrode.
7. The capacitive acceleration sensor of claim 1 , wherein the isolator protrusions are positioned on the stationary electrode.
8. The capacitive acceleration sensor of claim 1 , wherein the isolator protrusions are positioned on the movable electrode.
9. The capacitive acceleration sensor of claim 1 , wherein the diamond-like DLC coating of the isolator protrusion is grown by ion beam deposition.
10. The capacitive acceleration sensor of claim 1 , wherein the diamond-like DLC coating of the isolator protrusion is grown by plasma enhanced chemical vapour deposition.
11. The capacitive acceleration sensor of claim 1 , wherein the diamond-like DLC coating of the isolator protrusion is grown by arc discharge deposition.
12. A capacitive acceleration sensor comprising at least one pair of electrodes, such that the pair of electrodes comprises a movable electrode responsive to the acceleration, at least one stationary electrode, and at least one isolator protrusion, wherein the isolator protrusion being coated with a diamond-like DLC coating,
wherein the quality of the diamond-like DLC coating film of the isolator protrusion has been improved by increasing the proportion of bonds sp 3 /sp 2 .
13. A capacitive acceleration sensor comprising at least one pair of electrodes, such that the pair of electrodes comprises a movable electrode responsive to the acceleration, at least one stationary electrode, and at least one isolator protrusion, wherein the isolator protrusion being coated with a diamond-like DLC coating,
wherein the quality of the diamond-like DLC coating film of the isolator protrusion has been improved by reducing the hydrogen content of the diamond-like DLC coating film.