Zero Row Sum CDM Drive Matrix for Input Sensing
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Solution Overview
Problem
Existing input sensing technologies face challenges in accurately detecting user inputs while minimizing noise and radiated emissions, particularly in touch sensor devices and fingerprint sensors, which can lead to reduced signal quality and non-compliance with electromagnetic radiation emission standards.
Innovation Solution
The implementation of a zero row sum code division multiplexing (CDM) drive matrix that deconvolves raw measurements to recover original signals, reducing radiated emissions and noise by driving transmitter electrodes in a manner that cancels out emissions, and using overlapping CDM blocks to reduce free parameters and improve image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional CDM drive matrices are used for input sensing, then signal detection capability is improved, but radiated emissions increase and noise is not effectively reduced
Solution Approach 1:
The patent applies preliminary anti-action by using a zero row sum CDM drive matrix that pre-configures the driving signals to cancel out radiated emissions. The drive matrix is specifically designed so that the sum of each row is zero, which causes the transmitter electrodes to generate equal and opposite signals that cancel each other's radiated emissions before they can propagate. This allows the system to maintain signal detection capability while preventing harmful radiated emissions.
2Measurement precision
If all transmitter electrodes are driven simultaneously with high power, then signal-to-noise ratio is improved, but radiated emissions and self-heating increase
Solution Approach 1:
The zero row sum CDM drive matrix pre-configures the driving signals to cancel out radiated emissions and reduce self-heating. By ensuring the sum of each row is zero, the system generates equal and opposite signals that cancel each other's harmful effects before they manifest. This allows high power driving for improved signal-to-noise ratio while preventing excessive self-heating and radiated emissions.
3Manufacturing precision
If overlapping CDM blocks are used, then free parameters are reduced and image reconstruction is improved, but measurement iterations are increased
Solution Approach 1:
The patent merges overlapping CDM blocks to reduce the number of free parameters and improve image reconstruction quality. By having CDM blocks overlap and share common transmitter electrodes, the system reduces redundancy and the number of independent parameters that need to be solved. This merging approach improves manufacturing precision and image reconstruction while the increased measurement iterations are managed through efficient iterative algorithms.
Data Source
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AI summary
Sensing systems and methods that utilize zero row sum code division multiplexing (CDM) drive matrices to reduce or eliminate radiative emissions. Measurements corresponding to an input received at a sensing region of the input device are obtained by driving a first subset of transmitters of the input device according to a first portion of a CDM drive matrix, wherein the CDM matrix is a zero row sum matrix, and obtaining first measurement signals with the plurality of receivers, and driving a second subset of the transmitters according to a second portion of the CDM drive matrix, wherein the first and second subsets of transmitters include at least one transmitter in common, and obtaining second measurement signals with the plurality of receivers. An image of the input may be generated based on the obtained measurements.