Electrostatic Input Sensor Noise Discrimination via Segmented Detection

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Solution Overview

Problem

Conventional input devices with electrostatic sensors often malfunction due to noise sources like high-frequency power supplies or broadcasting waves, leading to incorrect determination of input operations when a human body approaches or contacts the sensor.

Innovation Solution

An input device is designed with a noise detection electrostatic sensor that detects changes in capacitance caused by noise sources separately from human body interactions, using a larger detection surface and a high-frequency clock signal to improve noise detection, and a protective cover to prevent human body contact, allowing the control means to accurately distinguish between noise and human input signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional electrostatic sensor is used to detect human body approach or contact, then the input device can detect user input operations, but the sensor also detects noise signals from high-frequency power supplies or broadcasting waves causing malfunction

Engineering Contradiction:

Improvedetection accuracy of human body inputVSAvoidoperational reliability against noise interference

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent divides the detection function into two separate sensors: an input electrostatic sensor for detecting human body approach/contact and a noise detection electrostatic sensor for detecting noise signals. This segmentation allows each sensor to be optimized for its specific function and enables the control means to distinguish between valid input and noise by comparing signals from both sensors

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The control means acts as an intermediary that receives and compares signals from both the input electrostatic sensor and the noise detection electrostatic sensor. By processing both signals together, the control means can determine whether a signal from the input sensor represents a valid human input or noise interference, thereby resolving the contradiction between detection sensitivity and noise immunity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the electrostatic sensor has high sensitivity to detect subtle human body interactions, then input detection accuracy improves, but the sensor becomes more susceptible to noise signals

Engineering Contradiction:

Improvesensitivity to human body capacitance changeVSAvoidsusceptibility to electromagnetic noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The detection system is segmented into two specialized sensors: the input electrostatic sensor optimized for high sensitivity to human body capacitance changes, and the noise detection electrostatic sensor optimized for detecting electromagnetic noise. This allows the input sensor to maintain high sensitivity without being compromised by noise susceptibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent converts the harmful effect of noise into a useful signal by using the noise detection electrostatic sensor to detect noise signals. The detected noise information is then used by the control means to filter out corresponding interference from the input sensor signals, thereby transforming noise from a harmful factor into a basis for noise cancellation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly reduces malfunctions caused by noise, enabling precise determination of input operations by physically and accurately detecting only noise components and controlling the input operation accordingly, ensuring the sensitivity of the input electrostatic sensor remains uniform even with continuous noise inclusion.

Implementation Method 1

an electrostatic sensor that outputs an electrical signal by approach or contact of a part of a human body, such as a hand or a finger

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

When a hand or a finger of an operator of the electronic apparatus approaches or makes contact with the input surface of the input key facing the electrode, the capacitance of the electrode is changed

Methodology Applied

Scientific EffectElectrostatic induction: Electrostatic Induction

Implementation Method 3

the delay means 105 is a delay circuit including an electrode 102 and a resistor R formed on a dielectric substrate

Methodology Applied

Scientific EffectRC time constant:

Data Source

PatentUS7279904B2Input device

Publication Date: 2007.10.09 ALPS ALPINE CO LTD

AI summary

An input device is provided. The input device includes an input electrostatic sensor having an input electrode. A noise detection electrostatic sensor has a noise detection electrode disposed on a periphery of the input electrostatic sensor. A control unit is operable to receive an output signal from the input electrostatic sensor and a noise output signal from the noise detection electrostatic sensor and is operable to compare the output signal with the noise output signal to detect a noise component. The control unit is operable to discriminate the output signal and the noise output signal and is operable to control an input operation based on the output signal.