Reference Voltage Modulator for Capacitive Sensing

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Solution Overview

Problem

Existing input devices face challenges in accurately detecting input objects due to grounding conditions, which affect the reliability of capacitive sensing, especially in low ground mass scenarios, and require efficient power management to perform capacitive sensing without interfering with other components.

Innovation Solution

The implementation of a processing system with a reference voltage modulator that modulates reference voltage rails to mitigate grounding effects and acquire signals simultaneously from sensor electrodes, allowing for effective capacitive sensing while maintaining power efficiency and component compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitive sensing is performed using existing input devices, then input object detection is enabled, but grounding conditions reduce detection accuracy and reliability

Engineering Contradiction:

Improveinput object detection accuracyVSAvoidsensing reliability under grounding conditions

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A reference voltage modulator is introduced as an intermediary component that modulates the reference voltage supplied to sensor electrodes. This modulator acts as a mediator between the power supply and the sensing circuitry, enabling the system to differentiate between grounding effects and actual input object signals by modulating at a specific frequency and detecting the modulated component of the resulting signal.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The reference voltage is dynamically modulated in terms of its electrical parameters (frequency, amplitude) to create a time-varying signal. By changing the reference voltage parameters periodically, the system can distinguish the capacitive coupling signal from static grounding effects, as the modulated signal contains frequency information that grounding conditions do not possess.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If capacitive sensing is performed actively, then input detection capability is improved, but power consumption increases

Engineering Contradiction:

Improveinput detection capabilityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The reference voltage modulator operates periodically, modulating the reference voltage at specific intervals rather than continuously. This periodic modulation enables capacitive sensing to be performed in discrete measurement cycles, allowing the device to enter low-power states between measurements and significantly reducing overall power consumption while maintaining detection capability.

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If reference voltage is modulated to mitigate grounding effects, then signal normalization is achieved, but system complexity increases

Engineering Contradiction:

Improvesignal normalizationVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The reference voltage modulator is designed to perform multiple functions: it modulates the reference voltage to mitigate grounding effects, provides power to the sensor electrodes, and enables frequency-based signal differentiation. By consolidating these functions into a single component, the system achieves signal normalization without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If modulated reference voltage is used for capacitive sensing, then grounding condition effects are reduced, but interference with other components may occur

Engineering Contradiction:

Improvegrounding effect mitigationVSAvoidinterference with other components

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system incorporates signal processing that analyzes the resulting signals from sensor electrodes and identifies the modulated frequency component. By using feedback mechanisms to detect and extract only the modulated frequency components, the system can mitigate grounding effects while filtering out or ignoring interference from other components operating at different frequencies.

Inventive Principle:

Principle #23Feedback

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 enhances the accuracy of input detection by normalizing signal effects from grounding conditions and reduces power consumption by enabling capacitive sensing in low power states without disrupting other device components.

Implementation Method 1

capacitive sensing

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS10191597B2Modulating a reference voltage to preform capacitive sensing

Publication Date: 2019.01.29 SYNAPTICS INC

AI summary

This disclosure generally provides an input device modulates a reference voltage used to provide power to a plurality of power supplies and acquires, while modulating the reference voltage, first resulting signals from a plurality of sensor electrodes simultaneously at a central receiver. In input device also acquires second resulting signals from the sensor electrodes at a plurality of local receivers and mitigates an effect a grounding condition has on the second resulting signal using the first resulting signals.