Resistive Touch Panel Calibration Sequence and Parameter Stability

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Solution Overview

Problem

Conventional resistive film touch panel calibration methods often result in deteriorated accuracy of input coordinates due to the order of calibration, where parameters used in one-point touch calibration are rewritten during two-point touch calibration, leading to shifted input coordinates in one-point touch after two-point touch calibration.

Innovation Solution

A control apparatus and calibration method where the calibration in two-point touch is performed first, followed by one-point touch, using a microcomputer with a first calibrator for two-point touch and a second calibrator for one-point touch, setting parameters based on the two-point touch calibration to maintain accurate calibration for both touch types.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If calibration in one-point touch is performed prior to calibration in two-point touch, then initial calibration accuracy for one-point touch is improved, but input coordinates in one-point touch are shifted after two-point touch calibration

Engineering Contradiction:

Improveinput coordinates accuracyVSAvoidcalibration parameter stability

Core Design Contradiction:

Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent performs two-point touch calibration first to establish stable baseline parameters, then uses these parameters as fixed references during subsequent one-point touch calibration. This preliminary action ensures that the foundation parameters remain stable and prevent coordinate shifts in one-point touch operations.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If calibration in two-point touch is performed after calibration in one-point touch, then comprehensive calibration coverage is achieved, but parameters from one-point touch calibration are rewritten causing coordinate shifts

Engineering Contradiction:

Improvecalibration coverageVSAvoidinput coordinates accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent inverts the conventional calibration sequence by performing two-point touch calibration before one-point touch calibration. This inversion prevents the rewriting of stable parameters and eliminates coordinate shifts, while still achieving comprehensive calibration coverage for both touch types.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If calibration parameters are rewritten during two-point touch calibration, then updated calibration data is obtained, but input coordinates in one-point touch are shifted

Engineering Contradiction:

Improvecalibration completionVSAvoidinput coordinates accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies different calibration strategies to different touch types: two-point touch calibration establishes global baseline parameters that remain fixed, while one-point touch calibration uses these fixed parameters as references. This local quality approach ensures that parameter updates in one area do not negatively impact coordinate accuracy in another area.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11188174B2Control apparatus

Publication Date: 2021.11.30 DENSO TEN LTD

AI summary

A control apparatus according to an embodiment includes a microcomputer configured to function as a first calibrator and a second calibrator. The first calibrator performs a calibration in a two-point touch in which a number of touch points is two on a resistive film touch panel. The second calibrator performs the calibration in a one-point touch in which the number of the touch points is one based on a set value set by the first calibrator.