Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/125—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by capacitive pick-up
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
  • G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
  • G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
  • G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
  • G01P15/0802—Details

Definitions

• the invention is based on an acceleration sensor with a substrate, at least one web and a seismic mass, wherein the web and the seismic mass are arranged above a plane of the substrate.
• the seismic mass is arranged at least on two sides of the web, and suspended resiliently on the web.
• the web is anchored to the substrate by means of at least one anchoring.
• the substrate is made of a different material than the at least one web, mechanical stresses between the substrate and the
• Gluing or capping are caused. Since the web and the seismic mass are the much weaker compared to the substrate elements, these stresses are reduced by the fact that deform the web and the seismic mass. This alters the placement of the seismic mass relative to the substrate and other solid elements attached to the substrate. For example, in capacitively operating acceleration sensors as a result of a change in the distance of mobile electrodes to fixed electrodes, a zero error for the measured capacitance results.
• the patent DE 196 39 946 shows a micromechanical acceleration sensor having a surface micromechanical structure with two closely spaced suspension points between which a movable seismic mass extends, which is suspended at the two suspension points by means of suspension springs.
• the patent application DE 19523895 A1 shows a micromechanical rotation rate sensor with a surface micromechanical structure with a central suspension (a central suspension point) with a seismic mass arranged around it, which by means of suspension springs on the
• FIGS. 5 and 6 show in FIGS. 5 and 6 a micromechanical sensor with a central suspension and two seismic masses arranged opposite one another, which are connected to one another by means of connecting webs and suspended from the central suspension.
• European Patent Application EP 1083144 A1 shows a micromechanical device with a central suspension and two seismic masses arranged opposite one another, which are connected to one another by means of connecting webs and suspended from the central suspension by means of a connecting beam.
• the central suspension is located at the center (at the center axis of the area or center of mass) of the entire movable structure.
• EP 1626283 A shows a micromechanical device with a central suspension and two oppositely disposed seismic masses, which are interconnected by means of connecting webs and at the central suspension by means of a
• the central suspension is located in the center (on the central axis) of the entire movable structure. Furthermore, a plurality of movable electrodes and, in addition, a plurality of fixed electrodes are disclosed on the movable structure. The plurality of fixed electrodes has a common suspension, which in the vicinity the central suspension is arranged.
• the non-prepublished patent application DE 10 2006 033 636 shows a similar subject.
• the present invention has for its object to provide an acceleration sensor which is designed so that a zero error for the measured capacitance is avoided.
• the invention is based on an acceleration sensor with a substrate, at least one web and a seismic mass, wherein the web and the seismic mass are arranged above a plane of the substrate.
• the seismic mass is arranged at least on two sides of the web, and suspended resiliently on the web.
• the web is anchored to the substrate by means of at least one anchoring.
• the essence of the invention is that the at least one anchorage is located outside the center of gravity of the seismic mass.
• the at least one anchorage is in the immediate vicinity of the center of gravity, so that bending of the substrate and / or the seismic mass may affect the relative orientation of the web and the seismic mass to the substrate as little as possible.
• such acceleration sensors can be designed to save space on the substrate.
• An advantageous embodiment of the invention provides that at least two anchors are provided.
• the at least two anchors are in close proximity to one another, so that bending of the substrate can hardly influence the relative orientation of the web to the substrate.
• a particularly advantageous embodiment of the invention provides that the center of mass between the two anchors is arranged.
• the seismic mass is arranged annularly around the web.
• An advantageous embodiment of the invention provides that at least two webs are provided, on which the seismic mass is suspended resiliently.
• anchoring the seismic mass in one point or in a relatively small area is advantageous. This point need not be in the center of gravity of the seismic mass. Due to the load distribution, however, it has advantages if the point is close to the center of mass. If several anchors are provided, it is advantageous to have these anchors within a small area, i. in relation to the extent of the structure to be anchored relatively close to each other to arrange. For the load distribution, it is advantageous if the center of gravity is arranged between the anchors. At a capacitive
• Acceleration sensor are provided movable electrodes on the seismic mass and opposite stationary electrodes on the substrate. If a common anchoring of the stationary electrodes is provided, it is advantageous for achieving the lowest possible zero error to provide this joint anchoring in the vicinity of the anchoring of the seismic mass.
• Figure 1 shows an acceleration sensor with central suspension in the prior art.
• FIG. 2 shows a first embodiment of a device according to the invention
• FIG. 3 shows a second embodiment of a device according to the invention
• FIG. 4 shows a third embodiment of a device according to the invention
• FIG. 1 shows an acceleration sensor in the prior art as described in the non-prepublished patent application DE 10 2006 033 636.
• FIG. 1 shows an acceleration sensor made, for example, by depositing a polysilicon layer on an oxide layer, which in turn is provided on a silicon substrate. In the oxide layer recesses are formed so that in these recesses connections of the polysilicon layer are formed to the silicon substrate. The structures shown in FIG. 1 are then defined and the oxide layer removed in an etching process. The polysilicon layer remains connected to the silicon substrate.
• the acceleration sensor comprises a central web 1, a right web 2 and a left web 3, while the right web 2 and the left web 3 extend parallel to the central web 1 on the right or left side thereof.
• the central web 1, the right web 2 and the left web 3 are arranged above a substrate which runs in the plane of the paper and connected to the substrate in each case at a central anchoring area 4, a right anchoring area 5 and a left anchoring area 6.
• the anchors 4, 5, 6 with the substrate are located under the webs 1, 2, 3 and are not actually visible from this perspective and therefore shown in phantom.
• Each of the anchors 4, 5, 6 is centrally located, i. the anchors 4, 5, 6 are as close as possible or even just below the centers of gravity of the respective webs
• the anchors 4, 5, 6 are also located as close to each other as possible. They are therefore on a line that crosses the central web 1, the right web 2 and the left web 3 transversely.
• tines 7 of a right-hand electrode On the right side of the right web 2, which faces away from the central web 1, tines 7 of a right-hand electrode are formed. The tines 7 of the right-hand electrode engage in the tines 8 of a right seismic electrode. On the left side of the left web 3, which faces away from the central web 1, tines 7 of a left-hand electrode are formed. The tines 7 of the left stem electrode engage in the tines 8 of a left seismic
• the tines 8 of the left seismic electrode and the right seismic electrode are attached to a closed frame 9.
• the frame 9 and the tines 8 of the seismic electrodes are perforated, ie have a regular arrangement of through holes.
• the perforation allows an etching medium to penetrate to an underlying layer during the etching process so that the frame 9 and prongs 8 can be safely separated from the substrate.
• the tines 7 and the webs 1, 2, 3 may be perforated.
• the frame 9 is suspended on springs 10 at opposite ends of the central web 1.
• Each spring 10 consists of a plurality of elongated thin rods which are arranged parallel to each other. Two adjoining bars are spaced apart either at their ends or at their center.
• the springs 10 can therefore be easily deformed perpendicular to the parallel bars, but not parallel to it.
• the springs 10 are also arranged so that the frame, in particular along the three parallel webs 1, 2, 3 is displaceable. At the two ends of the web 1 in each case a transverse strut 11 is formed, which protects the fine prongs 7, 8 of the seismic electrodes against an action by the deformed springs 10.
• the pair of the left and left seismic electrodes and the pair of right and left seismic electrodes together form a differential capacitor.
• a left side capacitance between the left stator electrode and the left seismic electrode is subtracted from a right side capacitance between the right stator electrode and the right seismic electrode. Without an acceleration this difference is zero because of the distance from neighboring ones
• Tine pairs 7, 8 on both sides of the central web 1 is the same. If, due to an acceleration, a prong 7 of the left-hand stalk electrode moves away from an adjacent prong 8 of the left seismic electrode, a prong 7 of the right-hand stub of an adjacent prong 8 of the right seismic electrode feeds simultaneously. This takes the left-sided
• FIG. 2 shows a first embodiment of an acceleration sensor according to the invention with a center-near suspension.
• the middle web 1 is anchored to the underlying substrate by means of two anchors 41 and 42.
• the center of gravity 10 also often referred to as the centroid or the central axis
• the two anchors 41 and 42 are anchored to the underlying substrate by means of two anchors 41 and 42.
• the center of gravity 10 also often referred to as the centroid or the central axis
• FIG. 3 shows a second embodiment of an acceleration sensor according to the invention with a suspension close to the center.
• the central web 1 is divided into two parts, such that two webs 12 and 13 are provided, which are anchored with one anchorage 41 and 42 to the substrate.
• the center of mass 10 of the seismic mass 9 in this case passes through none of the webs 12, 13.
• the anchors 41 and 42 are not arranged at the center of gravity 10, but at a small distance next to it.
• the center of gravity 10 is also between the anchors 41 and 42nd
• FIG. 4 shows a third embodiment of an acceleration sensor according to the invention with a center-near suspension.
• the webs 2 and 3 of the left and right stem electrode are also anchored to the substrate with a plurality of anchors 51 and 52 or 61 and 62.
• the left and right hand electrode do not each have a common web 2, 3, but that the tines 7 are anchored individually or in small groups on the substrate.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Pressure Sensors (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=40418107

Family Applications (1)

Country Status (6)

Families Citing this family (19)

Family Cites Families (19)

• 2007
  • 2007-10-05 DE DE102007047592.8A patent/DE102007047592B4/de active Active
• 2008
  • 2008-09-24 US US12/680,715 patent/US8516890B2/en active Active
  • 2008-09-24 WO PCT/EP2008/062765 patent/WO2009047120A2/de active Application Filing
  • 2008-09-24 EP EP08804670A patent/EP2195664A2/de not_active Withdrawn
  • 2008-09-24 CN CN2008801102240A patent/CN101903778B/zh active Active
  • 2008-10-03 TW TW097138029A patent/TWI438431B/zh active

Non-Patent Citations (1)

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