Capacitive Touch Panel Phase Delay Compensation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Capacitive touch panels face limitations in scanning frequency due to phase delays when transmit electrodes are driven from both sides, leading to increased noise susceptibility and reduced options for avoiding common-mode interference.

Innovation Solution

A system with a controller that dynamically configures transmit and receive electrodes to compensate for phase delays by driving a first group of transmit electrodes from one side and a second group from the opposite side, allowing for increased scanning frequency by synchronizing receive electrodes with transmit electrodes sequentially or simultaneously through dynamically configured pathways.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If transmit electrodes are driven from both sides of the touch panel, then the scanning coverage is improved, but phase delays are introduced that limit scanning frequency

Engineering Contradiction:

Improvescanning coverageVSAvoidscanning frequency

Core Design Contradiction:

Area of stationary objectVSSpeed

Solution Approach 1:

The touch panel is divided into two distinct scanning groups: a first group of transmit electrodes driven from a first side and a second group of transmit electrodes driven from a second side. This segmentation allows each group to be scanned independently with optimized timing, resolving the phase delay issue while maintaining comprehensive coverage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The controller implements periodic scanning by alternating between the first group and second group of transmit electrodes in sequential phases. This periodic action allows the system to complete full scans at higher frequencies by breaking the continuous scan into manageable periodic cycles, overcoming the phase delay limitation.

Inventive Principle:

Principle #19Periodic action

2Productivity

If transmit electrodes are driven from both sides, then noise susceptibility increases, but driving from one side limits scanning frequency options

Engineering Contradiction:

Improvescanning frequencyVSAvoidnoise susceptibility

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

By segmenting the transmit electrodes into two groups driven from opposite sides with staggered timing, the system can complete scans faster (reducing noise exposure duration) while the sequential activation reduces common-mode interference affecting both sides simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The controller preliminarily configures the scanning sequence by first scanning the first group of transmit electrodes, then sequentially scanning the second group. This preliminary ordering allows optimization of each group's scanning parameters independently, enabling higher frequencies while managing noise exposure.

Inventive Principle:

Principle #10Preliminary action

3Speed

If phase delay compensation is implemented, then scanning frequency can be increased, but system complexity increases

Engineering Contradiction:

Improvescanning frequencyVSAvoidcontrol complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The control complexity is managed by segmenting the electrode groups and assigning each group to dedicated transmit electrode drivers. This modular approach simplifies the overall control architecture while enabling high-frequency scanning through coordinated operation of the segmented groups.

Inventive Principle:

Principle #1Segmentation

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 configuration enables higher scanning frequencies, such as up to 400 kHz, reducing noise exposure and improving interference handling, enabling more efficient and accurate touch panel operations.

Implementation Method 1

The controller is operable to dynamically configure the transmit electrodes and the receive electrodes to compensate for phase delays introduced by driving the transmit electrodes from different sides of the capacitive touch panel

Methodology Applied

Scientific EffectPhase delay compensation:

Implementation Method 2

A capacitive touch panel generally includes an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide (ITO). As the human body is also an electrical conductor, touching the surface of the panel results in a distortion of the panel's electric field, measurable as change in capacitance.

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9552117B2Capacitive touch panel with increased scan frequency using dynamic phase compensation

Publication Date: 2017.01.24 QUALCOMM INC

AI summary

A system includes a first group of transmit electrodes configured to be driven from a first side of a capacitive touch panel and a second group of transmit electrodes configured to be driven from a second side of the panel. The system also includes receive electrodes and a controller operatively coupled with the transmit electrodes and the receive electrodes. The controller is operable to dynamically configure the transmit electrodes and the receive electrodes to compensate for phase delays introduced by driving the transmit electrodes from different sides of the panel. A method includes driving a first group of transmit electrodes from a first side of a capacitive touch panel, driving a second group of transmit electrodes from a second side of the panel, and dynamically configuring the transmit electrodes and receive electrodes to compensate for phase delays introduced by driving the transmit electrodes from different sides of the panel.