Electrostatic Charge Variation Sensor for Foldable Display State Detection

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Solution Overview

Problem

Existing screen state detection methods for foldable and rollable devices are complex, consume high power, and suffer from noise in the environment, making them inefficient for accurately determining the open or closed state of the device.

Innovation Solution

A device and method utilizing an electrostatic charge variation sensor, a stimulus electrode, and a receiving electrode to detect whether a bendable display is in an open or closed state by decoding the sequence of measured electrostatic charge variations, providing a low-cost and low-power solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If capacitive sensing or magnetic and optical solutions are used for screen state detection, then detection capability is achieved, but power consumption increases and noise interference occurs

Engineering Contradiction:
Improvescreen state detection accuracyVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces complex magnetic and optical detection systems with a simpler electrostatic charge variation sensing mechanism. By using electrostatic fields instead of magnetic or optical fields, the system achieves screen state detection with lower power consumption and reduced noise sensitivity, directly resolving the contradiction between detection reliability and energy usage

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and isolates the essential detection function to a dedicated electrostatic charge variation sensor, separating it from other device functions. This extraction allows the sensor to operate independently with minimal power consumption while providing reliable screen state detection, addressing both the reliability and power consumption concerns

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If complex algorithms are used for screen state detection, then detection accuracy may improve, but device complexity increases

Engineering Contradiction:
Improvescreen state detection accuracyVSAvoidalgorithm complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent substitutes complex signal processing algorithms with a straightforward electrostatic charge variation measurement approach. By directly measuring charge variations that naturally occur during screen folding/unfolding, the system achieves accurate detection without requiring complex computational algorithms, thereby reducing device complexity while maintaining reliability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The electrostatic charge variation sensor automatically detects screen state changes through natural electrostatic field variations caused by screen movement. The detection process is self-regulating and requires minimal external control or complex algorithmic intervention, simplifying the overall system while maintaining high detection accuracy

Inventive Principle:
Principle #25Self-service

3Reliability

If traditional sensors are used for screen state detection, then detection function is provided, but noise from surrounding environment interferes with measurement

Engineering Contradiction:
Improvedetection functionVSAvoidenvironmental noise
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces magnetic and optical sensing systems that are susceptible to environmental noise with electrostatic charge variation sensing. Electrostatic fields are less affected by common environmental interferers such as electromagnetic radiation and optical disturbances, thereby improving reliability while reducing sensitivity to harmful environmental factors

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an electrostatic field as an intermediary between the screen structure and the detection mechanism. This intermediary field is generated by the screen's own movement and provides a clean signal that is isolated from external environmental noise, enabling reliable detection without interference from surrounding electromagnetic or optical environments

Inventive Principle:
Principle #24Intermediary (Mediator)

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 proposed solution effectively determines the screen state with high accuracy, reducing power consumption and noise interference, thus enhancing the operational efficiency of foldable and rollable devices.

Implementation Method 1

an electrostatic charge variation sensor that measures the variation of electrostatic charge received by the receiving electrode

Methodology Applied
Scientific EffectElectrostatic charge variation: Electrostatics

Data Source

PatentEP4213471B1Screen state detection using an electrostatic charge variation sensor
Publication Date: 2025.06.04 STMICROELECTRONICS SRL
  • EP4213471B1 patent drawingFigure 1
  • EP4213471B1 patent drawingFigure 2
  • EP4213471B1 patent drawingFigure 3A~3B

AI summary

The device and method for screen state detection may be used in conjunction with any device with a bendable display. The device (10) comprises a bendable display (12); a first stimulus electrode (18) configured to transmit a first key signal; a first receiving electrode (20) configured to receive an electrostatic charge variation in a surrounding environment; an electrostatic charge variation sensor (16) configured to measure the electrostatic charge variation, and generate electrostatic charge variation data based on the measured electrostatic charge variation; and a processor (14) configured to determine whether the bendable display is in an open state or a closed state based on the electrostatic charge variation data and the first key signal.