Microelectromechanical sensor and operating method for a microelectromechanical sensor

• US 8,424,382 B2
• Filed: 08/08/2007
• Issued: 04/23/2013
• Est. Priority Date: 09/15/2006
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Litef Gmbh (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Litef Gmbh (Northrop Grumman Corporation)
• Inventors: Spahlinger, Guenter
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/310,572
• Publication Number:
  US 20100186503A1
• Time in Patent Office: 2,085 Days
• Field of Search: 735/041.2, 735/041.4, 735/041.6
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5726 Signal processing
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Abstract

A microelectromechanical sensor and operating method therefor. The sensor has at least one movable electrode. An electrode arrangement is spaced apart from the movable electrode with a plurality of electrodes that can be driven separately and to which corresponding electrode signals can be applied that can be used to electrostatically set/change the application of force, the spring constant and the read-out factor of the movable electrode. An electrode signal generation unit is connected to the electrode arrangement and can be supplied with a force application signal, a spring constant signal and a read-out factor signal, which define the settings/changes to be brought about with regard to the application of force, spring constant and read-out factor of the movable electrode. The electrode signal generation unit generates each electrode signal in a manner dependent on the force application signal, the spring constant signal and the read-out factor signal and matches the electrode signals to one another so that the application of force, the spring constant and the read-out factor of the movable electrode can be set/changed to specific desired values independently of one another.

Claims

1. A microelectromechanical sensor, comprising:

at least one movable electrode,

an electrode arrangement spaced apart from the movable electrode and having a plurality of electrodes which can be driven separately and to which corresponding electrode signals can be applied, wherein the electrode signals can be used to electrostatically set/change the application of force to the movable electrode, a spring constant of an electrostatically generated spring force and a read-out factor of the resonator,

an electrode signal generation unit, which is connected to the electrode arrangement and can be supplied with a force application signal, a spring constant signal and a read-out factor signal, which define the settings/changes to be brought about with regard to the application of force, spring constant and read-out factor of the movable electrode, wherein the read-out factor is a gain factor for reading out the movement of the movable electrode, and wherein the force application signal generates a force that is independent of a deflection of the movable electrode,

wherein the electrode signal generation unit generates each electrode signal in a manner dependent on the force application signal, the spring constant signal and the read-out factor signal and matches the electrode signals to one another in such a way that the application of force, the spring constant and the read-out factor of a movable electrode can be set/changed to specific desired values independently of one another.

2. The microelectromechanical sensor as claimed in claim 1, characterized by

a charge transfer unit, which detects charge transfers occurring on the movable electrode, and

an evaluation unit, which determines the instantaneous movement of the movable electrode on the basis of the detected charge transfer.

3. The microelectromechanical sensor as claimed in claim 2, characterized

in that the electrode signal generation unit generates each electrode signal in a manner dependent on the force application signal, the spring constant signal and the read-out factor signal in such a way that the charge transfer only contains charge transfer components which originate from the movement of the movable electrode and from the value of the read-out factor.

4. The microelectromechanical sensor as claimed in claim 1, characterized

in that the electrode arrangement contains four electrodes.

5. The microelectromechanical sensor as claimed in claim 4, characterized

in that the four electrodes are grouped into two electrode pairs, wherein the electrodes are configured axially symmetrically with respect to a first axis, which separates the two electrode pairs, from one another, and axially symmetrically with respect to a second axis, which separates the electrodes of the respective electrode pairs among one another.

6. The microelectromechanical sensor as claimed in claim 5, characterized

in that the movable electrode is configured centrosymmetrically with respect to the point of intersection of the two axes of symmetry.

7. The microelectromechanical sensor as claimed in claim 5, characterized

in that the electrode signals are given by the following equations:

u_o1=√

{square root over (Δ

ω

−

m²+f)}+m

u_o2=−

√

{square root over (Δ

ω

−

m²+f)}+m

u_u1=√

{square root over (Δ

ω

−

m²−

f)}−

m

u_u2=−

√

{square root over (Δ

ω

−

m²f)}−

m

where

(Δ

ω

) represents the value of the spring constant signal,

(m) represents the value of the read-out factor signal,

and (f) represents the value of the force application signal, (u_o1, u_o2) represent the values of the electrode signals lying above the second axis, and (u_u1, u_u2) represent the values of the electrode signals lying below the second axis.

8. The microelectromechanical sensor as claimed in claim 7, characterized in that the following relation holds true:

|f|<

Δ

ω

−

m²

9. The microelectromechanical sensor as claimed in claim 1, characterized in that the movable electrode is embodied as part of a resonator.

10. The microelectromechanical sensor as claimed in claim 1, characterized by a second movable electrode, which is electrically connected to the at least one movable electrode,

a second electrode arrangement spaced apart from the second movable electrode and having a further plurality of electrodes which can be driven separately and to which corresponding electrode signals can be applied, wherein the electrode signals can be used to electrostatically set/change the application of force to the second movable electrode, a spring constant of an electrostatically generated spring force and a read-out factor of the second movable electrode, wherein the read-out factor is a gain factor for reading out the movement of the second movable electrode, and wherein the force application signal generates a force that is independent of a deflection of the second movable electrode,

a second electrode signal generation unit, which is connected to the second electrode arrangement and can be supplied with a second force application signal, a second spring constant signal and a second read-out factor signal, which define the settings/changes to be brought about with regard to the application of force, spring constant and read-out factor of the second movable electrode,

wherein the second electrode signal generation unit generates each electrode signal in a manner dependent on the second force application signal, the second spring constant signal and the second read-out factor signal and matches the electrode signals to one another in such a way that the second application of force, the second spring constant and the second read-out factor of the second movable electrode can be set/changed to specific desired values independently of one another and independently of the application of force, the spring constant and the read-out factor of the at least one movable electrode.

11. An operating method for a microelectromechanical sensor having at least one movable electrode and an electrode arrangement spaced apart from the movable electrode and having a plurality of electrodes which can be driven separately and to which corresponding electrode signals can be applied, comprising the following steps:

generation of the electrode signals in a manner dependent on a force application signal, a spring constant signal and a read-out factor signal, which define the settings/changes to be effected with regard to the application of force to the movable electrode, spring constant of an electrostatically generated spring force and read-out factor of the movable electrode, wherein the read-out factor is a gain factor for reading out the movement of the movable electrode, and wherein the force application signal generates a force that is independent of a deflection of the movable electrode,

application of the electrode signals to the corresponding electrodes in order to electrostatically set/change the application of force, the spring constant and the read-out factor of the movable electrode,

wherein each electrode signal is generated in a manner dependent on the force application signal, the spring constant signal and the read-out factor signal and the electrode signals are matched to one another in such a way that the application of force, the spring constant and the read-out factor of the movable electrode are set/changed to specific desired values independently of one another.