Interference Detection Circuit for Proximity Sensors

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Solution Overview

Problem

Proximity sensor devices face interference issues that can lead to incorrect determination of input object position and fingerprint matching errors due to large interference signals, which existing technologies fail to effectively mitigate.

Innovation Solution

The implementation of a circuit comprising a sensor electrode, current conveyor, mixer circuit, interference detection circuit, and auxiliary component that generates a differential current and interference alert signal to detect and mitigate interference signals, ensuring accurate input object detection and fingerprint sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a proximity sensor device is used to detect input objects, then the device can determine the presence and location of input objects, but large interference signals can cause incorrect determination of input object position and fingerprint sensing errors

Engineering Contradiction:

Improveinput object position determination accuracyVSAvoidinterference signal impact

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent segments the signal processing into multiple independent paths: a main signal path for normal operation and a separate interference detection path. The interference detection circuit (IDC) creates a replica of the resulting signal and processes it independently to detect interference signals, allowing the main path to focus on accurate position determination without being affected by interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an interference detection circuit (IDC) as an intermediary component that acts as a mediator between the sensor electrode and the final processing stage. The IDC generates a replica signal and uses it to detect interference signals, then provides interference alert signals to mitigate the harmful effects of interference on the main signal path, thereby protecting the measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If existing proximity sensor device architecture is used, then the device can operate with simple structure, but it cannot effectively detect and mitigate interference signals

Engineering Contradiction:

Improveinterference signal detection capabilityVSAvoidsensor device architecture complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the interference detection functionality with the existing sensor device architecture by integrating the interference detection circuit (IDC) into the signal processing path. The IDC is coupled to receive the resulting signal and works in conjunction with existing components like the current conveyor and mixer circuit, combining interference detection with normal signal processing in a unified architecture.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The interference detection circuit (IDC) serves multiple functions: it generates a replica of the resulting signal, detects interference signals in the replica, generates interference alert signals, and enables interference mitigation. This multi-functional component enhances reliability without requiring completely separate dedicated interference mitigation systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution effectively reduces the likelihood of incorrect input object position determination and fingerprint matching errors by detecting and mitigating interference signals, enhancing the usability and accuracy of proximity sensor devices.

Implementation Method 1

a mixer circuit configured to generate a differential current by demodulating the first replica of the resulting signal

Methodology Applied

Scientific EffectDemodulation:

Implementation Method 2

a current conveyor configured to generate a first replica of the resulting signal

Methodology Applied

Scientific EffectCurrent conveyor:

Data Source

PatentUS10394386B1Interference detection

Publication Date: 2019.08.27 SYNAPTICS INC

AI summary

An input device associated with a sensing region is disclosed. The input device includes: a sensor electrode configured to receive a resulting signal associated with the sensing region; a current conveyor configured to generate a first replica of the resulting signal; a mixer circuit configured to generate a differential current by demodulating the first replica of the resulting signal; an interference detection circuit (IDC) configured to: generate a second replica of the resulting signal based on the first replica; determine the second replica includes an interference signal based on a reference current; and generate an interference alert signal in response to determining the second replica includes the interference signal; and an auxiliary component configured to generate an output based on the differential current and the interference alert signal.