Input Device Offset Calibration Using Position Detection

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Solution Overview

Problem

Existing input devices with capacitance and force sensors face issues such as offset drift due to stress changes, temperature variations, and shape changes over time, leading to degraded detection precision and increased power consumption, especially when edges are held with one hand and the input surface is operated with the other.

Innovation Solution

An input device equipped with a position detection sensor and a load detection sensor, where a control unit executes offset calibration using input operation information from the position detection sensor to correct the load detection sensor's output, with the load detection sensor in a standby state until input operation is detected, and sampling rates adjusted for efficient calibration and reduced power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the force sensor continuously operates to detect load, then detection precision is maintained, but power consumption increases

Engineering Contradiction:

Improvedetection precisionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The force sensor operates dynamically by switching between standby mode and active detection mode based on touch panel activity. When the touch panel is inactive, the sensor remains in standby to conserve power. When touch input is detected, the sensor activates to perform offset calibration and load detection, thus adapting its operational state to system needs and resolving the contradiction between continuous precision and power savings.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The force sensor performs periodic offset calibration at specific intervals (when touch panel is inactive) rather than continuously operating. This periodic activation allows the sensor to maintain calibration accuracy while consuming power only during necessary calibration and detection periods, effectively balancing measurement precision with power consumption reduction.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If offset calibration is performed frequently, then detection accuracy is improved, but processing time is increased

Engineering Contradiction:

Improvedetection accuracyVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Offset calibration is performed in advance during periods when the touch panel is inactive, preparing the force sensor for accurate detection before actual use. This preliminary calibration ensures detection accuracy is ready when needed, without delaying subsequent load detection operations, thus resolving the contradiction between frequent calibration and processing time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system performs offset calibration automatically during idle periods without requiring external intervention or user action. The control unit autonomously determines when calibration is needed and executes it, optimizing the balance between maintaining accuracy and minimizing processing time impact on user operations.

Inventive Principle:

Principle #25Self-service

3Stability of the object's composition

If the force sensor operates continuously, then offset drift is reduced, but power consumption increases

Engineering Contradiction:

Improveoffset stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control unit monitors touch panel input status and uses this feedback to determine when to activate the force sensor for calibration. This feedback mechanism ensures calibration occurs at appropriate intervals to maintain offset stability while avoiding unnecessary continuous operation that would increase power consumption, effectively balancing stability and energy use.

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 enables efficient offset calibration and accurate load detection, reducing power consumption and preventing data loss, while ensuring smooth transitions between calibration and load detection phases.

Implementation Method 1

Japanese Unexamined Patent Application Publication No. 2009-87311 discloses an input device that detects a movement position using a capacitance sensor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

Japanese Unexamined Patent Application Publication No. 2009-87311 discloses an input device that detects a movement position using a capacitance sensor and detects an amount of pressing using a distortion sensor

Methodology Applied

Scientific EffectDistortion: Deformation

Data Source

PatentUS9846511B2Input device and control method using input device

Publication Date: 2017.12.19 ALPS ALPINE CO LTD

AI summary

An input device includes a position detection sensor capable of detecting an input operation position of an operation body on an operation surface, a load detection sensor capable of detecting a load in the input operation position, and a control unit capable of executing offset calibration to correct an offset of an output of the load detection sensor based on input operation information resulting from an output of the position detection sensor.