Capacitive Touch Lock Panel for Human vs Water Detection

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Solution Overview

Problem

Conventional touch-sensitive electronic locks are prone to accidental triggering due to water contact, leading to increased power consumption and incorrect operations, as their capacitive touch panels respond similarly to human and water interactions.

Innovation Solution

The electronic lock incorporates a shielding circuit around the touch switches to differentiate between human and water contact by using a scan control unit that scans touch switches with a scan signal and a driving signal, determining if the electric changes match pre-established touch conditions, thereby preventing accidental activation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a capacitive touch panel with earth wires around touch contacts is used to reduce noise interference, then the touch sensitivity is improved, but the panel becomes accidentally triggered by water contact

Engineering Contradiction:

Improvetouch sensitivityVSAvoidfalse trigger rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent divides the touch detection function into two separate circuits: a self-capacitance detection circuit for detecting touch contact and a mutual-capacitance detection circuit for detecting water contact. This segmentation allows each circuit to be optimized for its specific detection purpose, enabling the system to distinguish between genuine touch operations and water-induced false triggers while maintaining high touch sensitivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a control circuit as an intermediary that processes signals from both self-capacitance and mutual-capacitance detection circuits. This control circuit analyzes the combined signal patterns to differentiate between human touch (which affects both circuits) and water contact (which primarily affects the mutual-capacitance circuit), thereby preventing false triggers while preserving touch sensitivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the capacitive touch panel responds to water contact similarly to human contact, then the touch detection coverage is improved, but power consumption increases due to accidental activation

Engineering Contradiction:

Improvedetection coverageVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements a dynamic response mechanism where the lock control unit adjusts its behavior based on the type of contact detected. When water contact is detected through the mutual-capacitance circuit, the system dynamically changes its state to ignore or differently process the signal, preventing unnecessary activation sequences and reducing power consumption associated with accidental operations.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback mechanisms where the control circuit continuously monitors signals from both detection circuits and adjusts its interpretation of touch events accordingly. By analyzing the pattern and magnitude of capacitance changes in real-time, the system can distinguish between intentional user input and environmental interference, enabling adaptive power management that reduces consumption during false trigger conditions while maintaining full detection coverage.

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 design effectively distinguishes between human and water contact, preventing false triggers and allowing the lock to function accurately in humid environments, reducing power consumption and ensuring correct operation.

Implementation Method 1

detects, with respect to each of the touch contacts, the change in coupling capacitance between the touch contact and a reference ground of the circuit board

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

Since most of the human body is water, which has a relatively great dielectric constant, contact of a human body with the touch contact will cause a significant change in the coupling capacitance

Methodology Applied

Scientific EffectDielectric constant: Dielectric

Implementation Method 3

produce relatively strong capacitive coupling with the corresponding one of the earth wires. This strong capacitive coupling will increase the coupling capacitance between the touch contact and the reference ground

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS11145149B2Electronic lock

Publication Date: 2021.10.12 TONG LUNG METAL IND CO LTD

AI summary

An electronic lock includes an electric locking unit, a touch panel, and a control module. The control module stores a plurality of touch condition sets which are related to human contact. The control module executes an input scan operation on each touch switch of the touch panel, charges a self capacitor with a scan signal, and charges a mutual capacitor with a driving signal. The control module determines whether an electric change conforms with any one of the touch conditions. Through a structural design of the touch panel and a scan function design of the control module, the electronic lock can more accurately determine whether the touch panel is operated by human touch and can also normally operate in a humid environment.