Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
  • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
  • G01C19/5705—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis
  • G01C19/5712—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using masses driven in reciprocating rotary motion about an axis the devices involving a micromechanical structure

Definitions

• the present invention relates to a micromechanical rotation rate sensor with a substrate which has an anchoring device provided on the substrate, and with an annular flywheel which is connected via a spiral spring device to the anchoring device in such a way that the connection area with the anchoring device lies essentially in the ring center, so is that the annular flywheel mass a lying parallel to the substrate surface rotation axis Elage about an axis perpendicular to the sub stratoberflacne lying axis of rotation and at least elastically out of their R ⁇ deflectable.
• 100 denotes a substrate in the form of a silicon wafer.
• 10 Dezeicnnet an annular flywheel; 15, 15 ⁇ bending beam; 25 a bridge; 18, 18 ⁇ a respective beautiful spiral spring and 20, 20 ⁇ a base.
• the latter parts are made of polysilicon over a silicon oxide layer, the silicon oxide layer being removed later in the process by under-etching in order to make the parts deflectable relative to the substrate 100. Only the two bases 20, 20 'are anchored to the substrate 100 via the silicon oxide layer and form fixed points of the sensor structure.
• the function of the rotation rate sensor constructed in this way is based on the principle of the conservation of angular momentum of a rotating system.
• M is the moment of deviation
• J is the moment of inertia
• d ⁇ / dt is the angular velocity of the torsional vibration
• ⁇ is the desired rate of rotation
• the ring-shaped flywheel mass 10 rotating about the z-axis is moved by its y- Axis rotated, this evades by rotating around the x-axis.
• This penetration around the x-axis, which is determined by the above M is caused, at a constant angular velocity around the z-axis, is directly proportional to the selected rotation rate ⁇ .
• the problem underlying the present invention generally consists in the fact that the first ⁇ rei natural frequencies corresponding to the x-, y- and z-axes, which are indicated in the figure, do not have an optimal position or one that can be easily optimized in terms of process technology.
• the anchoring device has two opposite bases which are firmly connected to the substrate and are connected to one another by a bridge.
• a V-shaped spiral spring of the spiral spring device is attached in such a way that the apex is located on the bridge and the legs are spread out towards the flywheel at an opening angle.
• the first natural frequency about the z-axis can be set in accordance with the working frequency in the forced mode of the sensor.
• the detection resonance frequency of the sensor can thus be adjusted around the x and y axis from the substrate plane.
• the ratio of the natural frequencies to each other largely determines the sensor properties, such as sensitivity, interference immunity and temperature stability.
• micromechanical rotation rate sensor according to the invention with the features of claim 1 therefore has the particular advantage over the known approaches that the natural frequencies can be tuned easily and precisely and independently of one another via the opening angle or the width and length of the V-shaped spiral springs.
• the opening angle for both V-shaped spiral springs of the spiral spring device is the same. This means that only one angle has to be optimized for the natural frequencies.
• V-shaped spiral springs of the spiral spring device are such attached to the bridge so that they form an X-shape. This creates a symmetrical spiral spring shape.
• the opening angle is selected such that the natural frequency around the axis of rotation lying perpendicular to the substrate surface is lower than each natural frequency around an axis of rotation lying parallel to the substrate surface. This enables extraordinarily positive detection behavior to be achieved.
• the bases are wedge-shaped on the opposite sides.
• the bridge connects the two wedge tips. This gives the sensor good deflection around the z-axis.
• the bridge is suspended from the bases in a free-floating manner above the substrate.
• FIG. 1 shows a schematic top view of an embodiment of the micromechanical device according to the invention
• Fig. 2 is a schematic plan view of a known micromechanical rotation rate sensor.
• FIG. 1 shows a schematic top view of an embodiment of the micromechanical rotation rate sensor according to the invention.
• 30-33 bending spring legs of two V-shaped bending springs, 25 ' denote a bridge, 21, 21' base and 150 an electrical supply line.
• the ring-shaped flywheel 10 is connected to the anchoring device 21, 21 ', 25 via a spiral spring device consisting of the two V-shaped spiral springs in such a way that the anchoring device 20 lies essentially in the ring center, so that the ring-shaped flywheel mass 10 can be deflected elastically out of its rest position about the z-axis lying perpendicular to the substrate surface and the x-axis and y-axis lying parallel to the substrate surface.
• the anchoring device 21, 21 ', 25' has two opposing pedestals 21, 21 'which are fixedly connected to the substrate 100 and are wedge-shaped on the opposite sides, the bridge 25' connecting the two wedge tips to one another.
• the bridge 25 ' is suspended in a free-floating manner above the substrate 100 on the bases 21, 21'.
• the opening angle is the same for both V-shaped bending springs of the bending spring device, and the V-shaped bending
• the bending spring means are attached to the bridge 25 'in such a way that they add up to a symmetrical X-shape.
• the first natural frequency can be set around the z-axis.
• the natural frequency for the rotation from the substrate plane about the x or y axis can be set.
• the ratio of the natural frequencies to one another is determined in such a way that the sensor properties, e.g. Sensitivity, interference resistance and temperature stability, adopt an application-specific optimized value.
• the opening angle is selected such that the natural frequency around the z-axis perpendicular to the substrate surface is lower than each natural frequency around an axis of rotation lying parallel to the substrate surface, i.e. the x or y axis.
• the micromechanical rotation rate sensor according to this embodiment is preferably produced by silicon surface micromechanics.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Gyroscopes (AREA)
• Micromachines (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7923206

Family Applications (1)

Country Status (5)

Cited By (2)

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Citations (2)

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• 1999
  • 1999-09-24 DE DE19945859A patent/DE19945859A1/de not_active Withdrawn
• 2000
  • 2000-08-26 DE DE50008537T patent/DE50008537D1/de not_active Expired - Lifetime
  • 2000-08-26 EP EP00971236A patent/EP1218693B1/de not_active Expired - Lifetime
  • 2000-08-26 JP JP2001527175A patent/JP4605736B2/ja not_active Expired - Lifetime
  • 2000-08-26 WO PCT/DE2000/002931 patent/WO2001023837A1/de not_active Ceased
  • 2000-08-26 US US10/089,018 patent/US6776041B1/en not_active Expired - Lifetime

Patent Citations (2)

Non-Patent Citations (1)

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