Foldable Display Digitizer Loop Coil Design for Hovering Detection

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Solution Overview

Problem

Existing foldable display devices face challenges in accurately detecting the position and height of input units, such as styluses, in the folding area due to changes in the magnetic field, which can lead to malfunction and reduced event detection performance.

Innovation Solution

A foldable display device incorporating a digitizer with loop coils of varying widths and thicknesses in the folding and non-folding areas, where the digitizer increases the alternating current signal applied to loop coils in the folding area to enhance detection accuracy by minimizing line cracks and resistance, and includes a method to extend the folding area for precise hovering event detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the digitizer uses loop coils with uniform width and thickness across the folding and non-folding areas, then the manufacturing process is simple, but the detection accuracy of input unit position and height in the folding area deteriorates due to magnetic field changes

Engineering Contradiction:

Improvedetection accuracy of input unit position and heightVSAvoidloop coil structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by configuring loop coils with different widths and thicknesses in different areas. Specifically, loop coils in the folding area have a first width and first thickness, while loop coils in the non-folding area have a second width and second thickness. This local differentiation compensates for magnetic field changes in the folding area, thereby maintaining detection accuracy without requiring complex uniform structures across the entire device.

Inventive Principle:

Principle #3Local quality

2Reliability

If the digitizer increases the AC signal applied to loop coils in the folding area to compensate for magnetic field changes, then the detection performance in the folding area is improved, but the energy consumption increases

Engineering Contradiction:

Improveevent detection performance in folding areaVSAvoidenergy consumption of digitizer

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by selectively increasing the AC signal only to loop coils located in the folding area where magnetic field changes occur, rather than increasing the signal to all loop coils uniformly. The controller identifies which loop coils are in the folding area and applies enhanced signals only to those specific coils, thereby improving detection reliability in the folding area while minimizing overall energy consumption.

Inventive Principle:

Principle #16Partial or excessive action

3Measurement precision

If the loop coils in the folding area are made with greater width and lesser thickness, then the resistance is reduced and detection accuracy is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvehovering height detection accuracyVSAvoidloop coil width and thickness control

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by optimizing the physical dimensions of loop coils in the folding area - specifically setting them with greater width and lesser thickness compared to loop coils in the non-folding area. These parameter modifications reduce the resistance of loop coils in the folding area, thereby improving hovering height detection accuracy. The patent specifies that the first width is greater than the second width, and the first thickness is less than the second thickness, creating optimal electrical characteristics for the folding area.

Inventive Principle:

Principle #35Parameter changes

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

The solution enables accurate detection of input unit position and height in the folding area, reducing the likelihood of malfunction and improving event detection performance by optimizing loop coil design and signal boosting in the extended folding area.

Implementation Method 1

calculates a hovering height of the input unit based on a change in a magnetic field between the input unit and loop coils of the plurality of loop coils

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

calculates a hovering height of the input unit based on a change in a magnetic field between the input unit and loop coils

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS11455006B2Display device

Publication Date: 2022.09.27 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a folding area and a non-folding area, a display panel including a plurality of pixels, and a digitizer arranged at one side of the display panel and including a plurality of loop coils, where, when a hovering event of an input unit is detected in the folding area, the digitizer increases an alternating current signal applied to at least one loop coil of the plurality of loop coils arranged in the folding area, and calculates a hovering height of the input unit based on a change in a magnetic field between the input unit and loop coils of the plurality of loop coils, the loop coils including a loop coil overlapping the input unit and adjacent loop coils around the input unit.