Touch Sensing Integrator Reset Reduction for Rate and Noise

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Solution Overview

Problem

Conventional capacitive touch sensing arrays face limitations in sensing rate due to the time-consuming process of resetting the charge integrator circuit, which also generates noise from charge injection effects.

Innovation Solution

A sensing method that involves selecting a receiving electrode, resetting the integrator, and measuring output signals by providing different voltages to transmitting electrodes, allowing for the calculation of cross-capacitance or self-capacitance values without repeated integrator resets, thereby increasing sensing rate and reducing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the charge integrator circuit is reset at the beginning of each measurement, then the measurement accuracy is maintained, but the sensing rate is limited and noise is generated

Engineering Contradiction:

Improvecapacitance measurement accuracyVSAvoidsensing rate

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-charging the sensing electrode to a first voltage before measurement, and then switching to a second voltage for actual measurement without resetting the integrator. This preliminary preparation enables subsequent measurements to proceed without repeated integrator resets, thereby maintaining measurement accuracy while improving sensing rate.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements periodic action by using alternating voltage sequences (first voltage and second voltage) applied to transmitting electrodes in a systematic pattern. This periodic voltage switching enables differential measurement techniques that maintain precision while reducing the frequency of integrator resets, thus improving sensing rate.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If the charge integrator circuit is reset frequently, then measurement accuracy is maintained, but charge injection noise is generated

Engineering Contradiction:

Improvecapacitance measurement accuracyVSAvoidcharge injection noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potentially harmful effect of voltage transitions into a beneficial measurement technique by using differential voltage sequences. Instead of simply resetting the integrator (which causes noise), the patent uses controlled voltage switching with pre-charging steps that transform the voltage transition effects into useful differential measurements, thereby maintaining accuracy while reducing noise.

Inventive Principle:

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

Solution Approach 2:

The patent introduces an intermediary pre-charging voltage step between the integrator reset and the actual measurement. This intermediate pre-charge phase prepares the sensing electrode in a controlled manner, allowing the subsequent measurement voltage transition to be noise-free or low-noise, thus maintaining measurement accuracy without generating charge injection noise.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If multiple transmitting electrodes are measured sequentially, then cross-capacitance values are obtained, but measurement time increases

Engineering Contradiction:

Improvecross-capacitance measurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements continuity of useful action by maintaining the integrator in a continuous measurement state without repeated resets. The voltage switching between transmitting electrodes occurs while the integrator continues to integrate, enabling seamless sequential measurement of multiple electrodes. This continuous operation eliminates idle reset times and reduces total measurement time while maintaining cross-capacitance measurement accuracy.

Inventive Principle:

Principle #20Continuity of useful action

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 method enhances the sensing rate of touch sensing arrays by minimizing integrator resets and reducing noise from charge injection, allowing for more efficient detection of conductive objects on the sensing array.

Implementation Method 1

a sensing circuit connected to the sensing electrodes can detect the location of the object by measuring changes in capacitances associated with the electrodes and the object

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the process of resetting the charge integrator circuit also generates noise due to charge injection effects

Methodology Applied

Scientific EffectCharge injection effects:

Data Source

PatentUS9218096B2Sensing methods for touch sensing devices

Publication Date: 2015.12.22 INNOLUX CORP

AI summary

A sensing method for a touch sensing device is provided. In one embodiment, for one set of interlaced receiving electrode and transmitting electrodes of the touch sensing device, an integrator coupled to the receiving electrode is reset only one time. In another embodiment, for each group of sensing electrodes, an integrator coupled to the sensing electrodes is reset only one time. Accordingly, the rate at which the touch sensing array is sensed may be increased. Noise reduced by the process of resetting the integrator due to charge injection effects may be decreased.