Touch Sensor Panel Phase-Line Layout for Lower Static Capacitance

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Solution Overview

Problem

Touch sensor panels face challenges with increased static capacitance, which affects accuracy and power consumption, particularly when overlaying displays, leading to added weight, thickness, and decreased brightness.

Innovation Solution

Incorporating negative phase voltage lines that cross-under sense regions, allowing for the reduction of static capacitance by counteracting the positive phase voltage lines, thereby improving accuracy and reducing power usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a touch sensor panel is overlaid on a display, then touch sensitivity is achieved, but weight and thickness increase

Engineering Contradiction:
Improvetouch sensitivityVSAvoidpanel weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines the touch sensor panel and display into a single integrated structure where the front surface of the display serves as the touch-sensitive surface. This merging eliminates the need for a separate overlay panel, thereby reducing weight and thickness while maintaining touch sensitivity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The display structure is designed to serve multiple functions: it acts as both the visual display medium and the touch sensor panel. The front surface of the display performs dual roles as both the viewing surface and the touch-sensitive surface, reducing the need for additional components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a touch sensor panel is overlaid on a display, then touch sensitivity is achieved, but thickness increases

Engineering Contradiction:
Improvetouch sensitivityVSAvoidpanel thickness
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The touch sensor panel and display are merged into a single integrated structure. The front surface of the display serves as the touch-sensitive surface, eliminating the need for a separate overlay layer and thereby reducing overall thickness.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The display structure performs multiple functions simultaneously. The front surface serves as both the display viewing surface and the touch-sensitive surface, eliminating the need for additional layers and reducing thickness.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Power

If static capacitance in sense regions is increased, then signal strength is improved, but measurement accuracy deteriorates

Engineering Contradiction:
Improvesignal strengthVSAvoidtouch detection accuracy
Core Design Contradiction:
PowerVSMeasurement precision

Solution Approach 1:

The patent applies preliminary anti-action by driving voltage lines with negative phase signals to preemptively counteract the positive phase voltage lines. This creates a compensatory effect that reduces static capacitance in sense regions, thereby improving measurement accuracy while maintaining signal strength through controlled capacitance management.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The patent changes the electrical parameters by introducing negative phase voltage lines that modify the capacitance characteristics of the sense regions. This parameter change allows for reduced static capacitance, improving the signal-to-noise ratio and measurement accuracy.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If more voltage lines are added to reduce static capacitance, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvetouch detection accuracyVSAvoidvoltage line configuration
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the functions of additional voltage lines with existing display circuitry. The negative phase voltage lines are integrated into the existing display structure, sharing conductors and circuit elements, which reduces the overall complexity compared to implementing them as separate dedicated components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The voltage lines in the display structure serve multiple functions: they act as both display drive lines and touch sensor voltage lines. This multi-functionality reduces the need for separate dedicated voltage lines, thereby reducing device complexity while still achieving the goal of reducing static capacitance for improved accuracy.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 enhances the accuracy of touch sensor panels while minimizing power consumption and maintaining display brightness, resulting in thinner and more efficient touch-enabled devices.

Implementation Method 1

the second voltage lines configured for reducing the static capacitance in the sense region

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2391994B1Touch sensor panels with reduced static capacitance
Publication Date: 2022.03.30 APPLE INC
  • EP2391994B1 patent drawingFigure 1
  • EP2391994B1 patent drawingFigure 2
  • EP2391994B1 patent drawingFigure 3

AI summary

Capacitive touch panels may include a plurality of positive voltage lines that are driven at a first phase. These positive voltage lines may be used to provide the drive capacitance signal sensed by one or more sense regions. The touch panels may also include a plurality of negative phase voltage lines that are driven at a phase that is different than the first phase. Both the positive and negative voltage lines may cross-under one or more sense regions. The negative phase voltage lines are able to counter act and reduce the static capacitance in the sense regions.