Capacitive Pointer Reading With Matrix Electrodes for Higher Resolution
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Solution Overview
Problem
Existing pointer instruments require manual reading and lack efficient, low-energy, wireless, and cost-effective solutions for remote, automatic digital data transmission, and capacitive devices face limitations in measuring resolution due to limited electrode connections.
Innovation Solution
A capacitive reading device with a support having alternating radial electrodes and counter electrodes connected via an n×k connection matrix to a 1-of-k multiplexer, allowing a non-repeating connection pattern for unambiguous pointer position detection using a capacitance digital converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a small number of electrodes (e.g., 8 or 16) are connected to measuring electronics via conventional multiplexers, then the device complexity is reduced, but the measurement precision deteriorates because the measuring resolution is directly dependent on the number of electrodes
Solution Approach 1:
The electrode array is divided into multiple groups, with each group connected to a separate multiplexer channel. This segmentation allows more electrodes to be effectively utilized without requiring a single large multiplexer, thereby improving measurement resolution while keeping individual multiplexer units manageable in size and complexity.
Solution Approach 2:
The patent transitions from a one-dimensional linear arrangement of electrodes to a two-dimensional grid arrangement (rows and columns). This dimensional change enables more electrodes to be connected through a matrix of multiplexers, significantly increasing the number of measurable positions without proportionally increasing the complexity of a single multiplexer unit.
2Measurement precision
If large multiplexers or solutions comprising cascaded multiplexers are used to connect more electrodes, then the measurement precision improves, but the device complexity and cost increase making the solution resource-intensive and expensive
Solution Approach 1:
Instead of using a single large multiplexer or cascaded multiplexers, the patent segments the electrode connections into multiple smaller multiplexer units arranged in a matrix. Each unit handles a subset of electrodes, and the combined system achieves high resolution without the complexity and cost of a single large multiplexer.
Solution Approach 2:
The patent introduces a two-dimensional connection matrix where electrodes are arranged in rows and columns, each connected to separate multiplexer channels. This dimensional approach allows efficient scaling of electrode count without linearly increasing multiplexer complexity, as the connection structure distributes the routing load across multiple dimensions.
3Measurement precision
If optical reading devices use active illumination to overcome sensitivity to interference from extraneous light, then the measurement precision improves, but the use of energy increases
Solution Approach 1:
The patent replaces optical reading methods with a capacitive sensing system that uses electrical fields instead of light. This substitution eliminates the need for active illumination and associated energy consumption, while providing inherent immunity to optical interference from extraneous light sources.
Solution Approach 2:
The patent changes the sensing parameter from optical properties to electrical capacitance. By measuring capacitive coupling between electrodes and the pointer, the system achieves precise measurement without requiring light sources, thereby reducing energy consumption while maintaining or improving measurement precision.
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
Enables high-resolution, unambiguous detection of pointer positions with reduced energy consumption and cost, suitable for wireless transmission without requiring active illumination.
Implementation Method 1
By detecting a capacitive influence of a plurality of channels, the position of the pointer can be determined via the non-repeating pattern
Data Source
AI summary
A capacitive reading device for a pointer instrument, wherein n radial electrodes alternating with radial counter electrodes are arranged opposite the pointer instrument in an arc to capacitively detect the position of a rotating pointer of the pointer instrument, where the counter electrodes are electrically connected to one another and connected to a first measurement connection of a capacitance digital converter, the n electrodes are connected to a second measurement connection of the capacitance digital converter via an n×k connection matrix and a downstream 1-of-k multiplexer, the n×k connection matrix connects each of the n electrodes to in each case one of k channels of the 1-of-k multiplexer, the connection pattern varies along the arc with n variations of b from k, and where n>k≥b>1.