HK1158304B - Vibrating micro-mechanical sensor of angular velocity - Google Patents

Description

Vibrating micromechanical sensor of angular velocity

Technical Field

The present invention relates to a measuring device for measuring angular velocity, and more particularly to a vibrating-type micromechanical sensor of angular velocity. It is an object of the present invention to provide an improved sensor structure which enables reliable measurements with two or three degrees of freedom and with good performance, in particular in small vibrating micromechanical sensor solutions of angular velocity.

Background

The measurement technique based on a vibration-type sensor of angular velocity has proved to be a very reliable method of measuring angular velocity with a simple concept. The most commonly used working principle of vibrating sensors of angular velocity is the so-called tuning fork principle.

In a vibration-type sensor of angular velocity, some known primary motion is generated and is continued in the sensor. Subsequently, the movement to be measured by the sensor is detected as a deviation of the above-mentioned primary movement. In the tuning fork principle, the primary motion is the vibration of two linear resonators vibrating in anti-phase.

The external angular velocity affecting the sensor in a direction perpendicular to the direction of motion of the resonator produces a Coriolis force affecting the mass in the opposite direction. The coriolis force proportional to the angular velocity may be detected directly from the respective blocks, or may be detected by associating the respective blocks on the same rotational axis, and therefore the detected motion is an angular vibration in the direction of the angular velocity axis.

The main characteristics required of the angular velocity sensor are shock resistance and impact resistance. These requirements are extremely stringent, especially in high demand applications such as drive control systems in the automotive industry. Even a violent impact, such as an external impact by a stone or the like, or a shock by a car stereo system, should not affect the output of the angular velocity sensor.

The prior art is described below, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 shows a functional block diagram of a prior art vibrating micromechanical Z-axis sensor of angular velocity;

FIG. 2 shows a diagram of an exemplary capacitive embodiment of a vibrating micromechanical Z-axis sensor of angular velocity according to the prior art;

fig. 3 shows a functional block diagram of a prior art vibrating micromechanical X/Y-axis sensor of angular velocity.

Fig. 1 shows a functional block diagram of a vibrating micromechanical Z-axis sensor of angular velocity according to the prior art. The vibrating micromechanical Z-axis sensor of angular velocity described in the prior art comprises a mass 1, which mass 1 is supported in the X-axis direction by an excitation frame 2 via springs 4 and 5. The excitation frame 2 is further supported by the support structure 3 in the Y-axis direction by means of springs 6 and 7.

In the vibrating micromechanical Z-axis sensor of the prior art, the mass 1 and the excitation frame 2 surrounding the mass 1 are brought into a primary motion in the Y-axis direction by exciting the centrally located mass 1 and the excitation frame 2 by means of springs 6 and 7 supported by the support structure 3. The detection axis in the X-axis direction formed by the suspension springs 4 and 5 for supporting the block 1 in the excitation frame 2 is perpendicular to the above-described main motion.

When the above-described structure vibrating under this primary motion is rotated with respect to the Z-axis perpendicular to the surface plane, the mass 1 moving under this primary motion receives coriolis force in the X-axis direction perpendicular to the direction of motion thereof. Subsequently, further, the detection springs 4 and 5 determine the vibration amplitude and the vibration phase of the generated movement to be detected in addition to the damping.

Fig. 2 shows a diagram of an exemplary capacitive embodiment of a vibrating micromechanical Z-axis sensor of angular velocity according to the prior art. In the described Z-axis sensor of angular velocity, the common primary motion of mass 1 and excitation frame 2 is electrostatically excited by excitation comb structure 8 and detected by detection comb structure 9. On the other hand, the secondary motion (secondary motion) caused by the coriolis force is differentially detected by the capacitive comb structures 10 and 11. Such sensors usually differ by the fact that the two members are coupled to each other as described above, so that a structure is obtained which is extremely less sensitive to external mechanical disturbances. One such prior art sensor solution is described in US patent No. US 6,752,017.

Fig. 3 shows a functional block diagram of a prior art vibrating micromechanical X/Y-axis sensor of angular velocity. The principle of this sensor solution in the prior art is described in US patent No. US 5,377,544. The vibrating micromechanical X/Y-axis sensor of angular velocity described in the prior art comprises a rotating mass 12, which rotating mass 12 is supported centrally by a support structure 13 through suspension springs 14 and 15. The vibrating micromechanical X/Y-axis sensor of angular velocity according to the prior art further comprises capacitive electrodes 18 arranged above or below the rotating mass 12.

In the above-described vibrating type micro-mechanical X/Y axis angular velocity sensor of the related art, the centrally located rotating block 12 is excited into a primary motion, which is a motion rotating around the z axis in the surface plane, by the electrostatic excitation comb structure 16 and the primary motion detection comb structure 17. The detection axis in the direction in the X/Y plane formed by the support structure 13 and the suspension springs 14 and 15 is perpendicular to the rotation axis of the primary motion.

When the vibrating micromechanical X/Y-axis angular velocity sensor described in the prior art rotates with respect to the X-axis, coriolis force in phase with its velocity is generated in the rotating mass 12, and the torque with respect to the Y-axis generated by the spring 14 causes torsional vibration of the rotating mass 12. Accordingly, when the X/Y axis angular velocity sensor rotates with respect to the Y axis, coriolis force in phase with its velocity is generated in the rotating block 12, and the torque with respect to the X axis generated by the spring 15 causes torsional vibration of the rotating block 12. The generated vibration can be capacitively detected by the capacitive electrode 18.

For a large number of applications in consumer electronics, there is a need for angular velocity sensors having extremely small size and cost effectiveness. Measurement techniques in several degrees of freedom present challenges to angular velocity sensors, as excitation and detection in more than one degree of freedom are often required. In particular, it has proven to be a challenge to achieve cost-effectiveness when measuring angular velocities in one component relative to an axis in a surface plane and relative to an axis perpendicular to the surface plane.

The anti-phase in-plane angular vibration of two similar masses is described and disclosed in international patent application publication No. WO 2006070059a 1.

The cost effectiveness of an angular velocity sensor depends on the complexity of the electronic components required for the element, in addition to the surface area. The excitation motion occurring in several degrees of freedom in non-coaxial measuring resonators is perhaps the largest factor in increasing the surface area and complexity of the electronic components.

It is therefore an object of the present invention to obtain a structure suitable for a vibration-type angular velocity sensor of small size, with which the angular velocity can be measured in two degrees of freedom or three degrees of freedom by jointly exciting motion.

Disclosure of Invention

The object of the present invention is to provide such an improved vibrating sensor of angular velocity: which enables reliable measurement in two or three degrees of freedom and with good performance, especially in the solution of small vibrating sensors of angular velocity, which is significantly cost-effective compared to the solutions of the prior art, while it can be designed to be insensitive to coupling of external mechanical disturbances.

The invention provides a vibrating micromechanical sensor of angular velocity, comprising: at least two seismic masses suspended by a support structure and/or a spring structure; and a spring member for coupling the vibration blocks to each other. Wherein the sensor of angular velocity is adapted to measure the angular velocity with respect to two or three axes by means of electrodes of the vibrating mass and/or by means of a detecting comb structure incorporated in a manner associated with the vibrating mass, and the at least two vibrating masses of the sensor of angular velocity are adapted to be excited into primary motion vibration by means of a common mode.

Preferably, the at least two oscillating masses comprise at least one rotating mass. More preferably, the at least two vibrating masses comprise at least one linear mass. Preferably, the sensor of angular velocity further comprises at least one excitation frame structure. Further, preferably, the at least two vibration masses are supported by the excitation frame structure through springs. Further, preferably, the sensor of angular velocity further comprises an excitation comb structure adapted to excite the at least two vibrating masses into a primary motion by a common mode signal.

Preferably, the comb-like structure for detection is adapted to detect the above-mentioned primary motion differentially. Furthermore, preferably, the rotary mass is adapted to be vibrated in the primary motion in a surface plane around the z-axis synchronously with the excitation frame structure. Further, preferably, the rotary blocks are adapted to couple the motions of the respective excitation frame structures to each other in antiphase. Furthermore, it is preferred that inside the linear block there are spring structures connected to the support structure, which prevent the detecting comb structure for detecting the z-direction angular velocity from moving in a primary mode.

Preferably, the electrodes are adapted to measure vibrations generated by rotating the sensor of angular velocity relative to the x-axis. Preferably, the electrodes are adapted to measure vibrations generated by rotating the sensor of angular velocity with respect to the y-axis. Preferably, the comb-like structure for detection is adapted to measure vibrations generated by rotating the angular velocity sensor with respect to the z-axis. Preferably, the angular velocity sensor is implemented using a silicon-on-insulator (SOI) type wafer material. Preferably, the structure of the sensor of angular velocity is supported at the support area by a substrate and/or a cover. Preferably, the frame of the angular velocity sensor element is connected to the substrate and to a gas space sealing cover located above the structure of the angular velocity sensor.

Drawings

The invention and its preferred embodiments are described in detail below, with exemplary reference to the following drawings, in which:

FIG. 1 shows a functional block diagram of a prior art vibrating micromechanical Z-axis sensor of angular velocity;

FIG. 2 shows a diagram of an exemplary capacitive embodiment of a vibrating micromechanical Z-axis sensor of angular velocity according to the prior art;

FIG. 3 shows a functional block diagram of a prior art vibrating micromechanical X/Y-axis sensor of angular velocity;

figure 4 shows a functional block diagram of a vibrating micromechanical sensor of angular velocity according to the present invention, with three axes;

figure 5 shows a functional block diagram of a first alternative vibrating micromechanical sensor of angular velocity according to the present invention, with three axes;

figure 6 shows a functional block diagram of a second alternative vibrating micromechanical sensor of angular velocity according to the present invention, with three axes;

figure 7 shows a functional block diagram of a third alternative vibrating micromechanical sensor of angular velocity according to the present invention, with three axes; and

fig. 8 shows a functional block diagram of a vibrating micromechanical sensor of angular velocity according to the present invention, with two axes.

Fig. 1 to 3 have been described hereinbefore. The present invention and its preferred embodiments are explained below with reference to fig. 4 to 8.

Detailed Description

Fig. 4 shows a functional block diagram of a vibrating micromechanical sensor of angular velocity according to the present invention, with three axes. The vibrating micromechanical sensor of angular velocity with three axes described in the present invention comprises a rotating mass 34, which rotating mass 34 is supported centrally by a support structure 19 via springs 28 and 29 and in the X-direction by excitation frame structures 32, 33 via springs 30, 31. The rotating mass 34 further includes electrodes 37-40. In addition, the vibrating-type micro-mechanical sensor of angular velocity with three axes of the present invention further comprises linear masses 35 and 36 supported by the excitation frame structures 32, 33 in the X-axis direction by springs 45, 46. The excitation frame structures 32, 33 are supported in the Y-axis direction by the frame 23 around the sensor by bending springs 24-27. In addition, the vibrating-type micro-mechanical sensor of angular velocity according to the present invention, which has three axes, comprises: capacitive comb structures 47, 48 supported by the frame structures 32, 33 and energized by springs 41, 42; an excitation comb structure 43 connected to the excitation frame structures 32, 33; a comb-like structure for detection 44; a support spring 49 connected to the housing; and support structures 20-22.

The vibrating micro-mechanical sensor of angular velocity with three axes of the present invention is particularly suitable for implementation using Silicon On Insulator (SOI) type wafer materials. In the SOI wafer, support regions 19 to 22 can be provided on a substrate layer with an insulating film such as an oxide interposed therebetween, and the movable member can be separated from the substrate by selectively etching away the oxide in these support regions.

The structure of a vibrating micro-mechanical sensor of angular velocity with three axes of the invention is supported at support areas 19-22 by the substrate layer of the wafer and/or the wafer of a cover for sealing the gas space above the structure, and in addition, a frame structure 23 surrounding the above-mentioned members is also adhered to the substrate layer and to the cover.

In the vibrating micro-mechanical sensor of angular velocity with three axes of the present invention, the main motion of the structure obtained by the bonding is determined by the following components: bending springs 24-27 of the linearly moving excitation frame structure 32, 33; springs 28, 29 of the rotary block 34; and springs 30, 31 for coupling the blocks to each other.

In the vibrating-type micromechanical sensor of angular velocity with three axes of the present invention, spring structures 41, 42 and supporting springs 49 may also be present inside the linear masses 35, 36. The above-described spring structures 41, 42 are connected to the comb-like structures for detection 47, 48, and these spring structures prevent the comb-like structures for detection 47, 48 for detecting the angular velocity in the Z direction from moving in the primary mode. In addition, a support spring 49 is connected to the housing, which support spring in turn provides a degree of freedom to the comb-like structure 47, 48 for detection in the direction of the secondary movement to be detected. Thus, the springs 41, 42 also participate in the primary motion. However, in the solution of the invention, the comb-like structure 47, 48 for detection, which is fixed in the z-direction in the drawing, is not necessary.

In the vibrating-type micro-mechanical sensor of angular velocity with three axes of the present invention, the main motion is electrostatically excited by a common mode signal with the comb structures 43 for excitation placed opposite to each other, and is differentially detected by the comb structures 44 for detection. The central rotating mass 34 is synchronously vibrated in the surface plane about the z-axis by the excitation frame structures 32, 33, while the motions of the excitation frame structures 32, 33 are coupled in anti-phase with each other.

When the vibrator constituted by the three masses 34 to 36 that vibrate in the surface plane of the micro-mechanical angular velocity sensor having three axes obtained by the above-described coupling rotates with respect to the x-axis, the coriolis force that acts on the masses 34 to 36 generates a torque with respect to the y-axis that is in phase with the velocity thereof in the central rotating mass 34, and this torque causes torsional vibration of the rotating mass 34. The amplitude and phase of the vibrations that the rotating mass 34 undergoes depends in part on the springs 28, 30 and 31 that provide the degrees of freedom of detection, which are dimensioned with a compliance suitable for this mode so that the resonance of this mode is at a suitable frequency, typically slightly higher than the frequency of the common primary motion of the masses 34-36. The resulting vibration can be capacitively and differentially detected by rotating the electrodes 39 and 40 at the top of the mass 34. These electrodes 37-40 can be deposited, for example, as a thin metal film on the inner surface of the cover wafer.

When the vibrator constituted by the three masses 34 to 36 vibrating in the surface plane of the micro-mechanical angular velocity sensor having three axes of the present invention obtained by the above-described coupling rotates with respect to the y-axis, the rotating mass 34 receives a moment with respect to the x-axis in the same phase as its speed in its rotation, and the moment generates a secondary vibration with respect to the same x-axis. In this movement, the springs 29-31 are in turn twisted in a torsional mode, determining the amplitude and phase of the vibration, respectively. The resulting vibrations can be capacitively and differentially detected by electrodes 37 and 38 located on top of the rotating mass 34.

When the vibrator constituted by the three masses 34 to 36 vibrating in the main motion in the micromechanical sensor of angular velocity having three axes of the present invention obtained by the above-described coupling is rotated with respect to the z-axis perpendicular to the surface plane, the linear masses 35 and 36 moving in opposite directions receive coriolis forces in opposite directions in the x-axis direction. In this movement, the z-direction detection springs 45, 46, and 49 determine the amplitude and phase of the generated vibration, respectively. The z-direction vibration to be detected is differentially detected by capacitive comb structures 47 and 48 located inside the respective masses.

In the micromechanical sensor of angular velocity with three axes according to the present invention, the double differential detection in the z-direction is particularly insensitive to mechanical disturbances, since the linear and angular accelerations due to shocks and vibrations are cancelled out in the differential detection.

Fig. 5 shows a functional block diagram of a first alternative vibrating micromechanical sensor of angular velocity according to the present invention, with three axes. The first alternative vibrating micromechanical sensor of angular velocity with three axes of the invention described herein comprises a rotating mass 34 supported centrally by a support structure 19 through springs 28 and 29 and by excitation frame structures 50 and 51 in the X-axis direction through springs 30 and 31. The first alternative vibrating micromechanical sensor of angular velocity with three axes according to the present invention further comprises linear masses 52, 53 supported by the excitation frame structures 50, 51 in the direction of the X axis by means of springs. The excitation frame structures 50, 51 are supported in the Y-axis direction by a frame 23 surrounding the sensor by bending springs 24-27. The first alternative vibrating micromechanical sensor of angular velocity with three axes according to the present invention further comprises: comb-like structures 54 and 55 for z-direction capacitance detection supported by the support member 21; each excitation comb structure connected to an excitation frame structure 50, 51; and a comb structure for detection.

The first alternative vibrating micromechanical sensor of angular velocity with three axes of the present invention is particularly suitable to be implemented using silicon-on-insulator (SOI) type wafer materials. The structure of the first alternative vibrating micromechanical sensor of angular velocity according to the present invention with three axes is supported at support areas 19 and 21 by the substrate layer and/or the cover wafer of the wafer, and in addition a frame structure 23 surrounding the above mentioned components is connected to the substrate layer and to the cover wafer for sealing the gas space located above the above mentioned structure.

In a first alternative vibrating micromechanical sensor of angular velocity according to the present invention, having three axes, the main motion of the structure obtained by the bonding is determined by: bending springs 24-27 of the linearly moving excitation frame structure 50, 51; springs 28, 29 of the rotary block 34; and springs 30, 31 for coupling the blocks to each other. The central rotating mass 34 is synchronously vibrated in the surface plane about the z-axis by the excitation frame structures 50, 51, while the motions of the excitation frame structures 50, 51 are coupled in anti-phase with each other.

When the vibrator constituted by the three masses 34, 52, and 53 vibrating in the surface plane of the first alternative vibration type micro mechanical angular velocity sensor having three axes of the present invention obtained by the above-described coupling rotates with respect to the x-axis, the coriolis force that affects the masses 34, 52, and 53 generates a torque with respect to the y-axis in the central rotating mass 34 in phase with the velocity thereof, and this torque causes torsional vibration of the rotating mass 34. The amplitude and phase of the vibrations that the rotating mass 34 makes depends on the springs 28, 30 and 31, respectively, that provide the detection degrees of freedom, these springs being dimensioned with a softness suitable for the mode so that the resonance of this mode is at a suitable frequency, typically slightly higher than the main movement of the mass 34. The resulting vibration can be capacitively and differentially detected by rotating the electrodes of the mass 34.

When the vibrator constituted by the three masses 34, 52 and 53 vibrating in the surface plane of the first alternative vibration type micro-mechanical angular velocity sensor having three axes of the present invention obtained by the above-described coupling is rotated with respect to the y-axis, the rotating mass 34 receives in its rotation a moment with respect to the x-axis in phase with the velocity, which produces a sub-vibration with respect to the same x-axis. In this movement, the springs 29-31 are sequentially twisted in a torsional mode, thereby determining the amplitude and phase of the vibration, respectively. The resulting vibration can be capacitively and differentially detected by rotating the electrodes of the mass 34.

When the vibrator constituted by the three masses 34, 52, and 53 vibrating in the primary motion in the first alternative vibrating type micromachined angular velocity sensor having three axes of the present invention obtained by the above combination is rotated with respect to the z-axis perpendicular to the surface plane, the linear masses 52 and 53 moving in opposite directions receive coriolis forces in opposite directions in the x-axis direction.

In the first alternative vibration type micro-mechanical sensor of angular velocity having three axes of the present invention, the comb-like structures 54, 55 for capacitance detection in the z direction inside the respective masses described above can move together with the respective masses described above in the main movement direction. In the first alternative vibration-type micro-mechanical sensor of angular velocity having three axes, the vibration to be detected generated in the z direction can be differentially detected by the comb-like structures for capacitance detection 54, 55. The quadrature signal (quadrature signal) generated from the main motion of the detection comb is canceled in the differential sensing. The first alternative structure occupies less space and a stronger signal can be obtained at the same structure size.

Fig. 6 shows a functional block diagram of a second alternative vibrating micromechanical sensor of angular velocity according to the present invention, with three axes. The second alternative vibrating micromechanical sensor of angular velocity with three axes of the invention described herein comprises a central mass 71 supported centrally by the support member 56 through the springs 65, 66 and supported in the X-axis direction by the excitation frame structures 69 and 70 through the springs 67 and 68. The central mass 71 also includes electrodes 76 and 77. In addition, the sensor of angular velocity with three axes described here also comprises lateral blocks 72 and 73, which are supported by the excitation frame structures 69, 70 by means of springs. The side blocks 72, 73 also include electrodes 78, 79, respectively. The second alternative vibrating micromechanical sensor of angular velocity with three axes according to the present invention further comprises linear masses 74, 75 supported by the excitation frame structures 69, 70 in the X-direction by springs 84, 85. The excitation frame structures 69, 70 are supported by the frame structure 60 in the Y-axis direction by bending springs 61-64. Furthermore, a second alternative vibrating micromechanical sensor of angular velocity according to the present invention, having three axes, comprises: capacitive comb structures 86, 87 supported by the frame structures 69, 70 and energized by springs 80 and 81; an excitation comb structure 82 connected to the excitation frame structures 69, 70; a comb-like structure for detection 83; a support spring; and support members 57 to 59.

The second alternative vibrating micromechanical sensor of angular velocity with three axes of the present invention is particularly suitable to be implemented using silicon-on-insulator (SOI) type wafer materials. The structure of a second alternative vibrating micromechanical sensor of angular velocity according to the present invention having three axes is supported at support areas 56-59 by the substrate layer and/or the cover wafer of the wafer, and a frame structure 60 surrounding the above-mentioned members is also connected to the substrate layer and to the cover wafer for sealing the gas space above the above-mentioned structure.

In a second alternative vibrating micromechanical sensor of angular velocity according to the present invention, having three axes, the main motion of the structure obtained by the coupling is determined by: bending springs 61-64 of the linearly moving excitation frame structure 69, 70; springs 65, 66 of central block 71; and springs 67, 68 that couple the respective blocks to each other.

In the second alternative vibrating-type micro-mechanical sensor of angular velocity with three axes of the present invention, there may also be spring structures 80 and 81 connected to the support member 58 inside the linear blocks 74, 75, which spring structures prevent the detecting comb-like structures 86, 87 for detecting the angular velocity in the z direction from moving in the primary mode. Thus, the springs 80 and 81 also participate in the primary motion. However, in the solution of the invention, the comb-like structure for detection 86, 87 fixed in the z-direction in the drawing is not necessary.

In the second alternative vibrating-type micro-mechanical sensor of angular velocity with three axes of the present invention, the primary motion is electrostatically excited by the common mode signal through the oppositely placed comb-like structure for excitation 82 and differentially detected through the comb-like structure for detection 83. The central mass 71 of the sensor of angular velocity is synchronously vibrated in the surface plane about the z-axis by the excitation frame structures 69, 70, while the motions of the excitation frame structures 69, 70 are combined in anti-phase with each other.

When a vibrator constituted by five coupled masses 71 to 75 vibrating in the surface plane of a second alternative vibration type micro mechanical angular velocity sensor having three axes of the present invention rotates with respect to the y-axis, coriolis force acting on the masses 71 to 75 generates a torque with respect to the x-axis in the central mass 71 in phase with the velocity thereof, and the torque causes torsional vibration of the central mass 71. The amplitude and phase of the vibrations of the central mass 71 depend on the springs 66, 67, 68 providing the detection degrees of freedom, which are dimensioned with a softness suitable for the mode so that the resonance of the mode is at a suitable frequency, typically slightly higher than the primary motion. The resulting vibration can be capacitively and differentially detected by electrodes 76 and 77 located on top of the rotating mass 71. These electrodes 76 and 77 are typically deposited on the lower surface of the cap wafer.

When a vibrator constituted by five coupled masses 71 to 75 vibrating in the surface plane of a second alternative vibration type micro-mechanical angular velocity sensor having three axes of the present invention rotates with respect to the x-axis, the side masses 72, 73 suspended on the torsion spring are sequentially subjected to coriolis forces in phase with their velocities in the z-axis direction, which forces generate opposite-phase torsional vibrations with respect to the y-axis among them. The resulting vibrations can be capacitively and differentially detected by electrodes 78, 79 located on top of the side masses 72, 73.

When a vibrator constituted by five coupled masses 71 to 75 vibrating in a surface plane of a second alternative vibrating type micro-mechanical angular velocity sensor having three axes of the present invention is rotated with respect to a z-axis perpendicular to the surface plane, linear masses 74, 75 moving in opposite directions receive coriolis forces in opposite directions in the x-axis direction. In this movement, the z-direction detection springs 84, 85 alternately determine the amplitude and phase of the generated vibration, respectively. The vibration to be detected in the z direction is differentially detected by the capacitive comb structures 86, 87 inside the respective blocks. In the second alternative vibrating micro-mechanical sensor of angular velocity with three axes of the present invention, the double differential detection in the z-direction is particularly insensitive to mechanical disturbances, since the linear and angular accelerations due to shocks and vibrations are cancelled out in the differential detection. The second alternative described has the advantage of allowing a more efficient use of space and a better separation of the modes of the blocks.

Fig. 7 shows a functional block diagram of a third alternative vibrating micromechanical sensor of angular velocity according to the present invention, with three axes. A third alternative vibrating micromechanical sensor of angular velocity with three axes of the invention described herein comprises a rotating mass 34 supported centrally by a support structure 19 through springs 28, 29 and by an excitation frame structure 32 in the X-axis direction through springs 30. The rotating mass 34 further includes electrodes 37-40. The vibrating micro-mechanical sensor of angular velocity with three axes of the present invention further comprises a linear mass 35 supported by the excitation frame structure 32 in the X-direction by means of springs 45, 46. The excitation frame structure 32 is supported in the Y-axis direction by a frame 23 for forming the sensor periphery by bending springs 24, 25. Furthermore, the vibrating-type micro-mechanical sensor of angular velocity according to the present invention, having three axes, further comprises: capacitive comb structures 47, 48 supported by the actuating frame structure 32 by springs 41, 42; an excitation comb structure 43 connected to the excitation frame structure 32; a comb-like structure for detection 44; a support spring 49 connected to the housing; and support members 20 to 22.

The third alternative vibrating micromechanical sensor of angular velocity according to the present invention with three axes is particularly suitable to be implemented with silicon-on-insulator (SOI) type wafer materials. In an SOI wafer, the support regions 19-22 can be provided on a substrate layer with an insulating layer such as oxide interposed therebetween, and the movable member can be separated from the substrate by selectively etching away the oxide in these support regions.

The structure of a third alternative vibrating micro-mechanical sensor of angular velocity according to the present invention having three axes is supported at support areas 19 to 22 by a substrate layer of a wafer and/or a wafer of a cover for sealing a gas space located above the structure, and further, a frame structure 23 surrounding the respective members is connected to the substrate layer and to the cover.

In a third alternative vibrating micromechanical sensor of angular velocity according to the present invention, having three axes, the main motion of the structure obtained by the coupling is determined by: the bending springs 24, 25 of the linearly moving excitation frame structure 32; springs 28, 29 of the rotary block 34; and a spring 30 coupling the blocks to each other.

In the third alternative vibration-type micro-mechanical sensor of angular velocity with three axes of the present invention, there may also be spring structures 41, 42 and a support spring 49 inside the linear block 35, the spring structures 41, 42 being connected to the comb-like structures for detection 47, 48, the spring structures preventing the comb-like structures for detection 47, 48 for detecting angular velocity in the z-direction from moving in the primary mode, and in addition, the support spring 49 being connected to the housing, the support spring providing a degree of freedom in turn to the comb-like structures for detection 47, 48 in the direction of the secondary motion to be detected. Thus, the springs 41, 42 also participate in the primary motion. However, in the solution of the invention, the comb-like structure 47, 48 for detection, which is fixed in the z-direction in the drawing, is not necessary.

In the third alternative vibrating-type micro-mechanical sensor of angular velocity with three axes of the present invention, the primary motion is electrostatically excited by the comb-like structure for excitation 43 and is detected by the comb-like structure for detection 44. The rotating mass 34 is synchronously vibrated in the surface plane about the z-axis by the excitation frame structure 32.

When the vibrator constituted by the two masses 34, 35 vibrating in the surface plane of the third alternative vibration type micro mechanical angular velocity sensor having three axes of the present invention obtained by the above-described coupling rotates with respect to the x-axis, the coriolis force acting on the masses 34, 35 generates a torque with respect to the y-axis in phase with the velocity thereof in the rotating mass 34, and this torque makes the rotating mass 34 generate torsional vibration. The amplitude and phase of the vibrations of the rotating mass 34 depend on the springs 28, 30, which in turn provide the degrees of freedom of detection, and which are dimensioned with a softness suitable for the mode so that the resonance of the mode is at a suitable frequency, typically slightly higher than the common primary motion of the masses 34, 35. The resulting vibration can be capacitively and differentially detected by rotating the electrodes 39, 40 at the top of the mass 34. These electrodes 37-40 can be deposited, for example, as a thin metal film on the inner surface of the cover wafer.

When the vibrator constituted by the two masses 34, 35 vibrating in the surface plane of the third alternative vibration type micro-mechanical angular velocity sensor having three axes of the present invention obtained by the above-described coupling rotates with respect to the y-axis, the above-described rotating mass 34 receives a moment with respect to the x-axis in phase with its speed, and this moment generates a sub-vibration with respect to the same x-axis. In this movement, the springs 29 and 30 are in turn twisted in a torsional mode, determining the amplitude and phase of the vibrations, respectively. The resulting vibrations can be capacitively and differentially detected by electrodes 37 and 38 located on top of the rotating mass 34.

When the vibrator constituted by the two masses 34, 35 vibrating in the main motion in the third alternative vibrating type micro-mechanical angular velocity sensor having three axes of the present invention obtained by the above-described coupling is rotated with respect to the z-axis perpendicular to the surface plane, the linearly moving mass 35 receives the coriolis force vibrating in the x-axis direction in phase with the velocity thereof. In the generated motion, the amplitude and phase of the generated vibration are respectively determined by the z-direction detection springs 45, 46, and 49. The z-direction vibration to be detected is differentially detected by capacitive comb structures 47, 48 located inside the above mentioned blocks.

In the third alternative vibrating micro-mechanical sensor of angular velocity with three axes of the present invention, single-ended detection in the z-direction is particularly sensitive to mechanical disturbances, since even linear accelerations due to shocks and vibrations displace the mass 35. The greatest advantage of this embodiment is the extremely small size and the simple, easy to implement structure.

The angular velocity sensor having three axes of the present invention can be variously modified within the scope of the present invention, in addition to the respective exemplary configurations described above.

Fig. 8 shows a functional block diagram of a vibrating micromechanical sensor of angular velocity according to the present invention, with two axes. The vibrating micromechanical sensor of angular velocity with two axes of the invention described here comprises a rotating mass 71 supported centrally by a support structure 19 by means of springs 28 and 29 and supported in X-direction by an excitation frame structure 32 by means of springs 30. The rotating mass 71 also includes electrodes 76 and 77. Furthermore, the vibrating micromechanical sensor of angular velocity with two axes according to the present invention described herein also comprises a linear mass 35 supported by the excitation frame structure 32 in the direction of the X axis by means of springs 45 and 46. The excitation frame structure 32 is supported in the Y-axis direction by a frame 23 for forming the sensor periphery by bending springs 24, 25. In addition, the vibrating micromechanical sensor of angular velocity with two axes of the invention described herein further comprises: capacitive comb structures 47, 48 supported by the actuating frame structure 32 by springs 41, 42; an excitation comb structure 43 connected to the excitation frame structure 32; a comb-like structure for detection 44; a support spring 49 connected to the housing; and support structures 20-22.

The vibrating micromechanical sensor of angular velocity with two axes of the present invention is particularly suitable to be implemented using silicon-on-insulator (SOI) type wafer materials. In the SOI wafer, the support regions 19 to 22 can be provided on a substrate layer with an insulating layer such as oxide interposed therebetween, and the movable member can be separated from the substrate by selectively etching away the oxide in these support regions.

The structure of a vibrating micromechanical sensor of angular velocity according to the invention with two axes is supported in support areas 19-22 by a substrate layer of the wafer and/or a wafer of a cover for sealing the gas space located above the structure, and a frame structure 23 surrounding the components is also connected to the substrate layer and to the cover.

In the vibrating micromechanical sensor of angular velocity with two axes according to the present invention, the main motion of the structure obtained by the coupling is determined by the following components: the bending springs 24, 25 of the linearly moving excitation frame structure 32; springs 28, 29 of the turning block 71; and a spring 30 coupling the blocks to each other.

In the vibrating-type micromechanical sensor of angular velocity with two axes according to the present invention, spring structures 41, 42 and supporting springs 49 may also be present inside the linear mass 35. The spring structures 41, 42 are connected to the comb-like structures for detection 47, 48, which prevent the comb-like structures for detection 47, 48 for detecting the angular velocity in the z direction from moving in the primary mode. In addition, support springs 49 are connected to the housing, which support springs provide degrees of freedom to the comb-like structures 47, 48 for detection, respectively, in the direction of the secondary motion to be detected. Thus, the springs 41, 42 also participate in the primary motion. However, in the solution of the invention, the comb-like structure 47, 48 for detection, which is fixed in the z-direction in the drawing, is not necessary.

In the vibrating-type micro-mechanical sensor of angular velocity with two axes of the present invention, the primary motion is electrostatically excited by the comb-like structure for excitation 43 and detected by the comb-like structure for detection 44. The rotating mass 71 is synchronously vibrated in the surface plane about the z-axis by the excitation frame structure 32.

When the vibrator constituted by the two masses 35 and 71 vibrating in the surface plane of the micromechanical sensor of angular velocity having two axes according to the present invention obtained by the above-described coupling rotates with respect to the y-axis, the coriolis force that affects the masses 35 and 71 generates a torque with respect to the x-axis that is in phase with the velocity thereof in the rotating mass 71, and this torque causes torsional vibration of the rotating mass 71. The amplitude and phase of the vibrations of the rotating mass 71 depend on the springs 29, 30, respectively, which provide the detection freedom, and which are dimensioned with a softness suitable for the mode so that the resonance of the mode is at a suitable frequency, typically slightly higher than the common primary movement of the masses 35, 71. The resulting vibration can be capacitively and differentially detected by rotating the electrodes 76, 77 at the top of the mass 71. These electrodes can be deposited, for example, as a thin metal film on the inner surface of the cover wafer.

When the vibrator constituted by the two masses 35 and 71 vibrating in the primary motion in the micromechanical angular velocity sensor having two axes according to the present invention obtained by the above-described coupling is rotated with respect to the z-axis perpendicular to the surface plane, the linearly moving mass 35 receives the coriolis force vibrating in the x-axis direction in phase with the velocity thereof. In the generated motion, the detection springs 45, 46 and 49 determine the amplitude and phase of the generated vibration, respectively. The vibration to be detected in the z-direction is differentially detected by capacitive comb structures 47 and 48 located inside the above-mentioned mass.

In the micromechanical sensor of angular velocity with two axes according to the present invention, single-ended detection in the z-direction is particularly sensitive to mechanical disturbances, since even linear accelerations due to shocks and vibrations displace the mass 35. Therefore, the present embodiment is most advantageous in an extremely small size and a simple structure which is easy to implement.

The angular velocity sensor having two axes of the present invention can be variously modified within the scope of the present invention, in addition to the respective exemplary configurations described above.

Compared with the sensor structure in the prior art, the vibrating micro-mechanical angular velocity sensor has the most remarkable advantages that: since the combined blocks perform a primary motion with several degrees of freedom, a structure with significant cost-effectiveness can be obtained. At the same time, the sensor can be designed to be insensitive to coupling of external mechanical disturbances due to the differential detection.

The vibrating micromechanical sensor of angular velocity according to the present invention may also enable extremely large signal levels, since the direction of motion is taken into account accurately. For example, the large size and moment of inertia of the rotating mass can be effectively utilized by large electrodes placed below or on top of the mass.

Claims (15)

1. A vibrating-type micromechanical sensor of angular velocity, comprising:

at least two vibration masses (34-36, 52-53, 71-75) suspended by support structures (19-23, 56-60) and/or spring structures (24-29, 49, 61-66); and

spring members (30-31, 67-68) for mutually coupling the vibration blocks (34-36, 52-53, 71-75),

characterized in that the sensor of angular velocity is adapted to measure the angular velocity with respect to two or three axes by means of electrodes (37-40, 76-79) of the vibrating mass (34-36, 52-53, 71-75) and/or by means of a comb-like structure (44, 47-48, 54-55, 83, 86-87) for detection arranged in a manner correlated with the vibrating mass (34-36, 52-53, 71-75), and in that

The at least two vibrating masses (34-36, 52-53, 71-75) of the sensor of angular velocity are adapted to be excited into primary motion vibration by a common mode and are adapted to be excited into primary motion vibration

The at least two vibration blocks (34-36, 52-53, 71-75) comprise at least one linear block (35-36, 52-53, 72-75).

2. The sensor of angular velocity according to claim 1, characterized in that the at least two vibrating masses (34-36, 52-53, 71-75) comprise at least one rotating mass (34, 71).

3. The sensor of angular velocity according to claim 2, characterized in that, the sensor of angular velocity further comprises at least one excitation frame structure (32-33, 50-51, 69-70).

4. An angular velocity sensor according to claim 3, wherein the at least two vibrating masses (34-36, 52-53, 71-75) are supported by the excitation frame structure (32-33, 50-51, 69-70) by means of springs (30-31, 45-46, 67-68, 84-85).

5. Sensor of angular velocity according to claim 4, characterized in that it further comprises an exciting comb structure (43, 82), said exciting comb structure (43, 82) being adapted to excite said at least two vibrating masses (34-36, 52-53, 71-75) into a primary motion by a common mode signal.

6. Sensor of angular velocity according to any of the previous claims 1, 2, 4 and 5, characterized in that the detecting comb structure (44, 47-48, 54-55, 83, 86-87) is adapted for differential detection of the primary motion.

7. Sensor of angular velocity according to any of the preceding claims 4 and 5, characterized in, that the rotating mass (34, 71) is adapted to be vibrated in the surface plane around the z-axis with the primary motion synchronized by the excitation frame structure (32-33, 50-51, 69-70).

8. Sensor of angular velocity according to any of the preceding claims 4 and 5, characterized in that the turning blocks (34, 71) are adapted to couple the motion of each of the excitation frame structures (32-33, 50-51, 69-70) to each other in anti-phase.

9. Sensor of angular velocity according to any of the preceding claims 4 and 5, characterized in that inside the linear blocks (35-36, 52-53, 72-75) there are spring structures (41-42, 80-81) connected to the support structure (23, 60), these spring structures (41-42, 80-81) preventing the detection comb structures (47-48, 86-87) for detecting angular velocity in z-direction from moving in primary mode.

10. The sensor of angular velocity according to any of the preceding claims 1, 2, 4 and 5, characterized in that the electrodes (37-40, 76-79) are adapted to measure vibrations generated by rotating the sensor of angular velocity with respect to the x-axis.

11. The sensor of angular velocity according to any of the preceding claims 1, 2, 4 and 5, characterized in that the electrodes (37-40, 76-79) are adapted to measure vibrations generated by rotating the sensor of angular velocity with respect to the y-axis.

12. An angular velocity sensor according to any of the preceding claims 1, 2, 4 and 5, characterized in that the detecting comb structures (47-48, 54-55, 86-87) are adapted to measure vibrations generated by rotating the angular velocity sensor with respect to the z-axis.

13. An angular velocity sensor according to any of the preceding claims 1, 2, 4 and 5, characterized in that the angular velocity sensor is realized by a wafer material of the SOI type, i.e. of the silicon-on-insulator type.

14. The sensor of angular velocity according to any one of the preceding claims 1, 2, 4 and 5, characterized in that the structure of the sensor of angular velocity is supported by a substrate and/or a cover at a support area (19-22, 56-59).

15. Sensor of angular velocity according to the preceding claim 14, characterized in that the frame (23, 60) of the sensor element of angular velocity is connected to the substrate and to a covering for gas space sealing located above the structure of the sensor of angular velocity.