Micromechanical roatational rate sensor

Abstract

The present invention creates a micromechanical rotational rate sensor having a first Coriolis mass element ( 2 a ) and a second Coriolis mass element ( 2 b ) which are situated over a surface of a substrate ( 100 ); having an activating device by which the first Coriolis mass element ( 2 a ) and the second Coriolis mass element ( 2 b ) are able to have vibrations activated along a first axis (x); and having a detection device by which deflections of the first Coriolis mass elements ( 2 a ) and of the second Coriolis element ( 2 b ) are able to be detected along a second axis (y), which is perpendicular to the first axis (x), on the basis of a correspondingly acting Coriolis force; the first axis (x) and second axis (y) running parallel to the surface of the substrate ( 100 ); the detecting device has a first detection mass device ( 3 a, 3 a ′) and a second detection mass device ( 3 b, 3 b ′); and the centers of gravity of the first Coriolis mass element ( 2 a ), the second Coriolis mass element ( 2 b ), the first detection mass device ( 3 a, 3 a ′) and the second detection mass device ( 3 b, 3 b ′) coincide at a common mass center of gravity (SP) when they are at rest.

What is claimed is:  
     
         1 . A micromechanical rotational rate sensor having: 
 a first Coriolis mass element ( 2   a ) and a second Coriolis mass element ( 2   b ) which are situated over a surface of a substrate ( 100 );    an activating device by which the first Coriolis mass element ( 2   a ) and the second Coriolis mass element ( 2   b ) is able to have vibrations activated along a first axis (x); and    a detecting device by which deflections of the first Coriolis mass elements ( 2   a ) and of the second Coriolis element ( 2   b ) are able to be detected along a second axis (y), which is perpendicular to the first axis (x), on the basis of a correspondingly acting Coriolis force;    the first axis (x) and second axis (y) running parallel to the surface of the substrate ( 100 );    the detecting device having a first detection mass device ( 3   a ,  3   a ′) and a second detection mass device ( 3   b ,  3   b ′); and    the centers of gravity of the first Coriolis mass element ( 2   a ), the second Coriolis mass element ( 2   b ), the first detection mass device ( 3   a ,  3   a ′) and the second detection mass device ( 3   b ,  3   b ′) coinciding at a common mass center of gravity (SP) when they are at rest.    
     
     
         2 . The micromechanical rotational rate sensor as recited in  claim 1 , 
 wherein the first detection mass device ( 3   a ,  3   a ′) is connected to the first Coriolis mass element ( 2   a ) via first springs ( 7   a ,  7   a ′) which are designed to be flexible along the first axis (x) and stiff along the second axis (y), and is connected to the substrate ( 100 ) via second springs ( 6   a ,  6   a ′), which are designed to be stiff along the first axis (x) and flexible along the second axis (y); and    the second detection mass device ( 3   b ,  3   b ′) is connected to the second Coriolis mass element ( 2   b ) via third springs ( 7   b ,  7   b ′) which are designed to be flexible along the first axis (x) and stiff along the second axis (y), and is connected to the substrate ( 100 ) via fourth springs ( 6   b ,  6   b ′), which are designed to be stiff along the first axis (x) and flexible along the second axis (y).    
     
     
         3 . The micromechanical rotational rate sensor as recited in  claim 1  or  2 , 
 wherein the activating device has a first activating mass device ( 1   a ,  1   a ′) and a second activating mass device ( 1   b ,  1   b ′) and the centers of gravity of the first activating mass device ( 1   a ,  1   a ′) and the second activating mass device ( 1   b ,  1   b ′) also coincide at the common mass center of gravity (SP) when they are at rest.  
 
     
     
         4 . The micromechanical rotational rate sensor as recited in  claim 3 , p 1  wherein the first activating mass device ( 1   a ,  1   a ′) has a first activating mass element ( 1   a ) and a second activating mass element ( 1   a ′), and the second activating mass device ( 1   b ,  1   b ′) has a third activating mass element ( 1   b ) and a fourth activating mass element ( 1   b ′), which are able to be individually activated via a respective comb actuator ( 12   a ,  12   b ,  13   a ,  13   b ,  12   a ′,  12   b ′,  13   a ′,  13   b ′).  
     
     
         5 . The micromechanical rotational rate sensor as recited in  claim 4 , 
 wherein the first and the second activating mass device ( 1   a ,  1   a ′) are connected to the first Coriolis mass element ( 2   a ) via the fifth springs ( 8   a ,  8   a ′) which are designed to be stiff along the first axis (x) and flexible along the second axis (y), and are connected to the substrate ( 100 ) via the sixth springs ( 5   a ,  5   a ′), which are designed to be flexible along the first axis (x) and stiff along the second axis (y); and the third and the fourth activating mass element ( 1   b ,  1   b ′) are connected to the second Coriolis mass element ( 2   b ) via the seventh springs ( 8   b ,  8   b ′) which are designed to be stiff along the first axis (x) and flexible along the second axis (y), and are connected to the substrate ( 100 ) via the eighth springs ( 5   b ,  5   b ′), which are designed to be flexible along the first axis (x) and stiff along the second axis (y).    
     
     
         6 . The rotational rate sensor as recited in one of the foregoing claims, 
 wherein the first Coriolis mass element ( 2   a ) has the shape of a closed polygonal frame, preferably of an essentially square frame.    
     
     
         7 . The rotational rate sensor as recited in  claim 6 , 
 wherein the second Coriolis mass element ( 2   b ) is situated within the first Coriolis mass element ( 2   a ), and has a polygonal shape, preferably an essentially square shape.    
     
     
         8 . The rotational rate sensor as recited in  claim 2 , 
 wherein the first Coriolis mass element ( 2   a ) and the second Coriolis mass element ( 2   b ) are able to have vibrations that are in phase opposition activated along a first axis (x) by the activating device; and the first detection mass device ( 3   a ,  3   a ′) and the second detection mass device ( 3   b ,  3   b ′) are able to be deflected in various directions along the second axis y, based on the acting Coriolis force.    
     
     
         9 . The rotational rate sensor as recited in one of the foregoing claims, 
 wherein the first detection mass device ( 3   a ,  3   a ′) has a first detection mass element ( 3   a ) and a second detection mass element ( 3   a ′), and the second detection mass device ( 3   b ,  3   b ′) has a third detection mass element ( 3   b ) and a fourth detection mass element ( 3   b ′), which each have a plurality of fingers (F), which are situated along the second axis (y); and at the fingers (F), movable electrodes ( 16   a ,  16   b ,  16   a ′,  16   b ′) are provided, which cooperate with the electrodes ( 14 ,  14 ′), that are firmly anchored to the substrate ( 100 ), to detect the deflections.    
     
     
         10 . The rotational rate sensor as recited in one of the preceding claims  4  through  9 , 
 wherein the first activating mass element ( 1   a ) and the third activating mass element ( 1   b ), as well as the second activating mass element ( 1   a ′) and the fourth activating mass element ( 1   b ′) are coupled to one another pairwise by a connecting spring ( 9 ,  9 ′) in each case, which is designed to be flexible along the first axis (x) and preferably stiff along the second axis (y).  
 
     
     
         11 . The rotational rate sensor as recited in one of the preceding claims  9  or  10 , 
 wherein the first detection mass element ( 3   a ) and the third detection mass element ( 3   b ), as well as the second detection mass element ( 3   a ′) and the fourth detection mass element ( 3   b ′) are coupled pairwise to one another by a respective connecting spring ( 10 ,  10 ′) in each case, which is preferably designed to be stiff along the first axis (x) and flexible along the second axis (y).  
 
     
     
         12 . The rotational rate sensor as recited in one of the foregoing claims, 
 wherein a mechanical coupling is provided along the x axis and along the y axis by a coupling spring device between the Coriolis mass elements ( 2   a ,  2   b ), the coupling spring device being designed to be flexible along the x axis and along the y axis.