Micromechanical Sensor Spring Structure Quadrature Compensation
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Solution Overview
Problem
Micromechanical sensors experience wobbling motion and quadrature errors due to inclined etching flanks, leading to faulty deflection and increased complexity in compensation measures.
Innovation Solution
The implementation of two spring elements with compensation elements that are shaped and positioned to mimic a straight etched spring, even with non-vanishing trench angles, effectively preventing wobbling motion by coupling sections of the spring elements and adapting their width and shape to the trench angle, thereby reducing quadrature errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching processes are used to create silicon structures, then manufacturing is simplified, but inclined etching flanks cause wobbling motion and quadrature errors
Solution Approach 1:
The spring element is divided into multiple sections (first section, second section, third section) with different width characteristics. The first and third sections have greater widths than the middle section, creating a segmented structure that compensates for inclined flanks. This segmentation allows the spring to maintain vertical alignment despite etching angle variations, resolving the contradiction between manufacturing simplicity and alignment precision.
Solution Approach 2:
The spring element's width parameter is deliberately varied along its length rather than maintaining a uniform width. By making the first and third sections wider than the middle section, the parameter change compensates for the inclined flank geometry. This parameter modification enables the spring to behave mechanically as if it were vertically etched, even when manufactured with standard inclined etching processes.
2Measurement precision
If additional compensation measures are implemented to reduce quadrature signals, then measurement precision improves, but device complexity increases
Solution Approach 1:
The quadrature compensation function is extracted from separate electronic compensation circuits and integrated directly into the mechanical spring structure itself. By embedding the compensation geometry within the spring element's physical form (through the varying width sections), the need for additional complex electronic compensation measures is eliminated, reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The spring element performs dual functions: it provides the necessary mechanical suspension for the mass element and simultaneously performs quadrature compensation through its geometric design. The segmented width structure enables the spring to self-correct alignment errors caused by inclined etching, making the system self-compensating without requiring external compensation mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in a compact, cost-effective micromechanical sensor with reduced quadrature signals, simplified manufacturing, and lower fault proneness, allowing for efficient mechanical quadrature compensation without increasing sensor height.
Implementation Method 1
a first and a second spring element (21, 22) which extend essentially in parallel to each other in sections and in particular are coupled to each other in sections
Implementation Method 2
a deflection movement of the two masses out of the drive plane being capacitively detected in order to determine a rotation rate of the micromechanical sensor
Data Source
AI summary
A micromechanical sensor is provided as including a substrate having a main extension plane and a mass element movable relative to the substrate, the movable mass element being coupled to the substrate via a spring structure, the spring structure including a first and a second spring element, the first and second spring elements extending essentially in parallel to each other in sections and being coupled to each other in sections, the spring structure including a first and a second compensation element for quadrature compensation, the first compensation element being connected to the first spring element, the second compensation element being connected to the second spring element, the first spring element having a first spring structure width extending along a transverse direction, the second spring element having a second spring structure width extending along the transverse direction, the first compensation element in a first subarea extending in parallel to the transverse direction along a first width, the first spring structure width and the first width being different, the second compensation element in a second subarea extending in parallel to the transverse direction along a second width, the second spring structure width and the second width being different.