Accelerometer with folded beams
First Claim
Patent Images
1. An accelerometer, comprising:
- a measurement mass for detecting acceleration, including;
a housing having a cavity;
one or more spring mass assemblies positioned within the cavity, each spring mass assembly including;
a support structure;
one or more resilient folded beams coupled to the support structure; and
a mass coupled to the resilient folded beams; and
one or more electrode patterns coupled to the spring mass assembly;
a top cap wafer coupled to the measurement mass, including a top capacitor electrode; and
a bottom cap wafer coupled to the measurement mass, including a bottom capacitor electrode.
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Accused Products
Abstract
Disclosed is an accelerometer for measuring seismic data. The accelerometer includes a proof mass that is resiliently coupled to a support structure by folded beams, S-shaped balanced beams, straight beams, and/or folded beams with resonance damping. The support structure further includes travel stops for limiting transverse motion of the proof mass.
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Citations
46 Claims
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1. An accelerometer, comprising:
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a measurement mass for detecting acceleration, including;
a housing having a cavity;
one or more spring mass assemblies positioned within the cavity, each spring mass assembly including;
a support structure;
one or more resilient folded beams coupled to the support structure; and
a mass coupled to the resilient folded beams; and
one or more electrode patterns coupled to the spring mass assembly;
a top cap wafer coupled to the measurement mass, including a top capacitor electrode; and
a bottom cap wafer coupled to the measurement mass, including a bottom capacitor electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
one or more range-of-motion stops coupled to the support structure for limiting the movement of the mass in the direction of the stops.
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3. The accelerometer of claim 2, wherein one or more of the range-of-motion stops include one or more perforations for minimizing fluid damping.
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4. The accelerometer of claim 2, wherein one or more of the range-of-motion stops are coupled to the side walls of the support structure.
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5. The accelerometer of claim 2, wherein one or more of the range-of-motion stops are coupled to the interior corners of the support structure.
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6. The accelerometer of claim 1, wherein one or more of the resilient folded beams include:
one or more range-of-motion limit stops for limiting movement of the mass in the direction of the stops.
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7. The accelerometer of claim 1, wherein one or more of the folded beams further include:
a mass for dampening out resonances of the resilient folded beam.
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8. The accelerometer of claim 1, wherein one or more of the spring mass assemblies further include:
one or more soft range-of-motion limit stops for compliantly limiting movement of the mass in the direction of the stops.
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9. The accelerometer of claim 1, wherein one or more of the spring assemblies further include:
corner tethers for coupling the corners of the mass to the opposing interior corners of the support structure.
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10. The accelerometer of claim 1, wherein one or more of the resilient folded beams further include one or more cutouts for minimizing stress concentrations.
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11. The accelerometer of claim 1, wherein one or more of the resilient folded beams further include one or more cutouts for minimizing webbing formation during the manufacture of the folded beams.
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12. The accelerometer of claim 1, wherein one or more of the resilient folded beams further include a webbing artifact having a hole for preventing the propagation of cracks into the resilient folded beams.
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13. An accelerometer, comprising:
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a measurement mass for detecting acceleration, including;
a housing having a cavity;
one or more spring mass assemblies positioned within the cavity, each spring mass assembly including;
a support structure;
one or more resilient S-shaped beams coupled to the support structure; and
a mass coupled to the resilient S-shaped beams; and
one or more electrode patterns coupled to the spring mass assembly;
a top cap wafer coupled to the measurement mass, including a top capacitor electrode; and
a bottom cap wafer coupled to the measurement mass, including a bottom capacitor electrode. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
one or more range-of-motion stops coupled to the support structure for limiting the movement of the mass in the direction of the stops.
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15. The accelerometer of claim 14, wherein one or more of the range-of-motion stops include one or more perforations for minimizing fluid damping.
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16. The accelerometer of claim 14, wherein one or more of the range-of-motion stops are coupled to the side walls of the support structure.
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17. The accelerometer of claim 14, wherein one or more of the range-of-motion stops are coupled to the interior corners of the support structure.
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18. The accelerometer of claim 13, wherein one or more of the S-shaped beams include:
one or more range-of-motion limit stops for limiting movement of the mass in the direction of the stops.
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19. The accelerometer of claim 13, wherein one or more of the S-shaped beams further include:
a mass for dampening out resonances of the resilient folded beam.
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20. The accelerometer of claim 13, wherein one or more of the spring mass assemblies further include:
one or more soft range-of-motion limit stops for compliantly limiting movement of the mass in the direction of the stops.
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21. The accelerometer of claim 13, wherein one or more of the spring assemblies further include:
corner tethers for coupling the corners of the mass to the opposing interior corners of the support structure.
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22. The accelerometer of claim 13, wherein one or more of the S-shaped beams further include one or more cutouts for minimizing stress concentrations.
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23. The accelerometer of claim 13, wherein one or more of the S-shaped beams further include one or more cutouts for minimizing webbing formation during the manufacture of the S-shaped beams.
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24. The accelerometer of claim 13, wherein one or more of the S-shaped beams further include a webbing artifact having a hole for preventing the propagation of cracks into the S-shaped beams.
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25. An accelerometer, comprising:
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a measurement mass for detecting acceleration, including;
a housing having a cavity;
one or more spring mass assemblies positioned within the cavity, each spring mass assembly including;
a support structure;
one or more resilient straight beams coupled to the support structure; and
a mass coupled to the resilient straight beams; and
one or more electrode patterns coupled to the spring mass assembly;
a top cap wafer coupled to the measurement mass, including a top capacitor electrode; and
a bottom cap wafer coupled to the measurement mass, including a bottom capacitor electrode. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
one or more range-of-motion stops coupled to the support structure for limiting the movement of the mass in the direction of the stops.
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27. The accelerometer of claim 26, wherein one or more of the range-of-motion stops include one or more perforations for minimizing fluid damping.
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28. The accelerometer of claim 26, wherein one or more of the range-of-motion stops are coupled to the side walls of the support structure.
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29. The accelerometer of claim 26, wherein one or more of the range-of-motion stops are coupled to the interior corners of the support structure.
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30. The accelerometer of claim 25, wherein one or more of the straight beams include:
a range-of-motion limit stop for limiting movement of the mass in the direction of the stop.
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31. The accelerometer of claim 25, wherein one or more of the straight beams further include:
a mass for dampening out resonances of the straight beam.
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32. The accelerometer of claim 25, wherein one or more of the spring mass assemblies further include:
one or more soft range-of-motion limit stops for compliantly limiting movement of the mass in the direction of the stops.
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33. The accelerometer of claim 25, wherein one or more of the spring assemblies further include:
corner tethers for coupling the corners of the mass to the opposing interior corners of the support structure.
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34. The accelerometer of claim 25, wherein one or more of the resilient straight beams further include one or more cutouts for minimizing stress concentrations.
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35. The accelerometer of claim 25, wherein one or more of the resilient straight beams further include one or more cutouts for minimizing webbing formation during the manufacture of the resilient folded beams.
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36. The accelerometer of claim 25, wherein one or more of the straight beams further include a webbing artifact having a hole for preventing the propagation of cracks.
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37. An accelerometer, comprising:
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a measurement mass for detecting acceleration, including;
a housing having a cavity;
one or more spring mass assemblies positioned within the cavity, each spring mass assembly including;
a support structure;
one or more resilient beams coupled to the support structure; and
a mass coupled to the resilient beams; and
one or more electrode patterns coupled to the spring mass assembly;
a top cap wafer coupled to the measurement mass, including a top capacitor electrode; and
a bottom cap wafer coupled to the measurement mass, including a bottom capacitor electrode;
wherein the resilient beams are selected from the group consisting of folded resilient beams, S-shaped beams, and straight beams.
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38. A sensor package, comprising:
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(a) a sensor having a mass suspended by a plurality of springs which induce mechanical vibrational modes in the sensor, the sensor providing an output signal indicative of acceleration detected by the mass;
(b) a controller coupled to the sensor in a closed-loop configuration, the controller in response to the output signal of the sensor providing a digital output proportional to the acceleration detected by the sensor, the controller in the closed-loop operation having at least one predefined frequency band for stable operation relative to the frequency of mechanical vibrational modes induced in sensor; and
wherein the plurality of springs are tuned so that the frequency of the induced mechanical vibrational modes remains substantially within at least one predetermined frequency band.- View Dependent Claims (39, 40, 41, 42)
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43. A sensor package, comprising:
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(a) a sensor having a mass suspended from a structure by a plurality of springs which induce mechanical vibrational modes in at least one direction of movement of the mass, the amplitude of the induced mechanical vibrational modes being a function of the mass of the springs;
(b) a controller coupled to the sensor in a closed loop operation for providing a digital output proportional to the acceleration detected by the sensor, the controller having a predetermined amplitude threshold level for detecting any mechanical vibrational modes of the sensor; and
wherein the mass of the springs is selected so that the amplitude of the mechanical vibrational modes induced in the sensor remains below the predetermined amplitude threshold level of the controller. - View Dependent Claims (44, 45, 46)
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Specification