Partial Touch Sensor Reads for Lower Power Detection

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Solution Overview

Problem

Existing touch sensor technologies face challenges in balancing interface circuitry complexity, performance, and power consumption, particularly in determining touch inputs on capacitive touch surfaces, which require full scanning of all sensing lines and excitation frequencies.

Innovation Solution

A method and apparatus for performing partial reads of touch sensors by identifying specific regions on the touch surface and exciting only the involved sensing lines with selected excitation frequencies, using transform-based reading to detect touch inputs in the frequency domain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full scanning of all sensing lines is performed to detect touch inputs, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The touch sensor surface is divided into multiple regions, and only the sensing lines within the identified region of interest are excited and scanned, while other sensing lines remain inactive. This segmentation allows the system to maintain touch detection accuracy within the relevant region while significantly reducing overall power consumption by excluding unrelated sensing lines from the scanning process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of performing complete scanning of all sensing lines across the entire touch surface, the system performs partial scanning only of the sensing lines that correspond to the identified region of interest. This partial action is sufficient to detect touch inputs where needed, while avoiding the excessive energy consumption of scanning the entire surface when only a portion requires attention.

Inventive Principle:

Principle #16Partial or excessive action

2Measurement precision

If full scanning of all sensing lines is performed to detect touch inputs, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidinterface circuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The reading circuitry is configured to selectively excite and read only specific sensing lines corresponding to the identified region, rather than requiring complex circuitry to manage and process signals from all sensing lines simultaneously. This segmentation simplifies the interface circuitry by reducing the number of active scanning channels while maintaining detection accuracy in the region of interest.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If full scanning of all sensing lines is performed to detect touch inputs, then measurement precision is improved, but time consumption increases

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidreading time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs partial scanning of only the sensing lines within the identified region of interest, significantly reducing the time required to complete a touch sensor read operation. This partial scanning approach maintains detection accuracy for touches within the relevant region while eliminating the time waste associated with scanning sensing lines that are not needed for the current touch interaction.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system can dynamically update the region of interest based on touch control information from software applications, performing targeted scans only when and where needed. This periodic updating of scan regions allows the system to adapt to changing touch requirements, maintaining high detection accuracy while minimizing overall scanning time across the entire touch surface.

Inventive Principle:

Principle #19Periodic action

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 reduces power consumption and simplifies frequency-domain processing while improving touch responsiveness and detection efficiency, allowing for simultaneous or sequential partial and aggregated touch region readings.

Implementation Method 1

A touch input to the touch surface alters the capacitance of the underlying or proximate capacitors, which alters the voltage of an analog excitation signal applied to the affected columns/rows.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS12449932B2Method and apparatus for performing partial reads of a touch sensor

Publication Date: 2025.10.21 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A technique for performing partial reads of a touch sensor (10) provides several advantages, including scalability to touch sensors with high sensing-line counts, and reductions in operating power. The technique involves identifying a region (46) of the touch surface (12) of the touch sensor (10) to be read and performing a partial read directed to the identified region. Rather than exciting all sensing lines of the touch surface (12), the partial read excites one or more of the sensing lines (18, 28) that are involved with the identified region (46), without exciting one or more of the uninvolved sensing lines (18, 28). Identifying the region or regions (46) to be read involves, for example, obtaining touch-control information from a software application (74) running on a host device (72) that includes the touch sensor (10).