In-Cell Touch Display Pressure Detection via Capacitance Analysis

Solution Overview

Problem

Existing in-cell touch displays require an additional pressure sensing circuit to detect force touch, which increases cost, product size, and weight, hindering cost savings and thinness.

Innovation Solution

A pressure detection method that utilizes the existing touch sensing electrodes by setting specific areas to exclude capacitance values affected by the touch, using capacitance changes to determine pressure without additional Z-axis sensing elements, and accounting for deformation errors over time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an additional pressure sensing circuit is added to detect force touch, then pressure detection capability is improved, but device complexity, cost, and weight increase

Engineering Contradiction:

Improvepressure detection capabilityVSAvoidnumber of sensing circuits

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The touch sensing electrodes are designed to serve dual functions: traditional touch detection and pressure detection. By analyzing capacitance changes in specific areas around the touched portion, the same sensing electrodes can determine both touch location and applied pressure, eliminating the need for separate pressure sensing circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing touch sensing system automatically provides pressure detection functionality through software processing of capacitance data. The controller identifies touched portions and analyzes capacitance values in surrounding areas to determine pressure, allowing the system to self-service the pressure detection function without additional hardware.

Inventive Principle:

Principle #25Self-service

2Adaptability or versatility

If an additional pressure sensing circuit is added to detect force touch, then pressure detection capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvepressure detection capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The touch sensing electrodes are designed to serve dual functions: traditional touch detection and pressure detection. By analyzing capacitance changes in specific areas around the touched portion, the same sensing electrodes can determine both touch location and applied pressure, eliminating the need for separate pressure sensing circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing touch sensing system automatically provides pressure detection functionality through software processing of capacitance data. The controller identifies touched portions and analyzes capacitance values in surrounding areas to determine pressure, allowing the system to self-service the pressure detection function without additional hardware.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If an additional pressure sensing circuit is added to detect force touch, then pressure detection capability is improved, but product size and weight increase

Engineering Contradiction:

Improvepressure detection capabilityVSAvoidproduct weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

The touch sensing electrodes are designed to serve dual functions: traditional touch detection and pressure detection. By analyzing capacitance changes in specific areas around the touched portion, the same sensing electrodes can determine both touch location and applied pressure, eliminating the need for separate pressure sensing circuits.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The existing touch sensing system automatically provides pressure detection functionality through software processing of capacitance data. The controller identifies touched portions and analyzes capacitance values in surrounding areas to determine pressure, allowing the system to self-service the pressure detection function without additional hardware.

Inventive Principle:

Principle #25Self-service

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

Enables pressure detection on in-cell touch displays without additional hardware, reducing costs and maintaining product thinness and lightness while achieving 3D touch functionality.

Implementation Method 1

detecting capacitance values of the touch sensing electrodes

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9983752B2Pressure detection method for in-cell touch display and mobile device using the same

Publication Date: 2018.05.29 FOCALTECH ELECTRONICS LTD

AI summary

A pressure detection method for an in-cell touch display and a mobile device using the same are provided. The pressure detection method comprises the steps of: providing a common voltage plane corresponding to touch sensing electrodes in the in-cell touch display; detecting capacitance values of the touch sensing electrodes; setting a first area and a second area according to a center of a touched portion when the in-cell touch display is determined as being touched, wherein the second area includes the first area; and excluding the capacitance values of the touch sensing electrodes in the first area, and using the capacitance values of the touch sensing electrodes in the second area to serve as a pressure detection value to determine a pressure exerted on the in-cell touch display.