Current Limiting Circuit for Display Devices

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Solution Overview

Problem

Existing display devices face challenges in efficiently limiting current to prevent overcurrent flow during transitions in video data, leading to increased element ratings, size, and cost, especially when using methods like frame memory which complicate the device configuration.

Innovation Solution

A current limiting circuit that detects supply current and reduces application voltage when it exceeds a threshold, using a diode for current detection and a bipolar transistor for control, with a simplified configuration that does not require frame memory.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a frame memory is provided to store video data and calculate total value before displaying images, then overcurrent flow can be prevented, but device complexity and cost increase

Engineering Contradiction:

Improvecurrent limiting reliabilityVSAvoiddevice configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the current limiting function from the video data processing sequence. Instead of storing video data in frame memory and calculating total values beforehand, the system directly monitors the actual current consumed by the display panel and limits it in real-time, eliminating the need for frame memory and complex pre-calculations

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements a feedback mechanism where the current limiting circuit continuously monitors the actual current consumed by the display panel and adjusts the application voltage accordingly. This closed-loop control ensures reliable current limiting without requiring predictive calculations or frame memory storage

Inventive Principle:

Principle #23Feedback

2Use of energy by stationary object

If luminance is limited based on calculated total value of video data, then power consumption is reduced, but image display may occur before calculation completes causing overcurrent

Engineering Contradiction:

Improvepower consumptionVSAvoidcurrent limiting reliability

Core Design Contradiction:

Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent applies preliminary action by having the current limiting circuit ready to immediately respond when overcurrent conditions are detected. The circuit is pre-configured with threshold values and control logic that activate before any potential damage can occur, ensuring both power reduction and reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses real-time feedback from current sensing to dynamically adjust application voltage. This ensures that power consumption is reduced through luminance limiting while simultaneously preventing overcurrent by immediately responding to actual current conditions, eliminating the delay inherent in pre-calculating video data totals

Inventive Principle:

Principle #23Feedback

3Reliability

If rated values of circuit elements are set according to overcurrent, then circuit reliability is ensured, but element size, mounting area, and cost increase

Engineering Contradiction:

Improvecircuit reliabilityVSAvoidmounting area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent applies preliminary protective action through the current limiting circuit that prevents overcurrent from reaching the display panel in the first place. By proactively limiting current to safe levels before they can cause damage, the circuit elements can be designed with lower rated values, reducing mounting area and cost while maintaining reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The current limiting circuit acts as an intermediary between the power source and the display panel. It mediates the current flow by actively regulating and limiting it to safe levels, thereby protecting downstream circuit elements from overcurrent damage without requiring them to be designed for higher current ratings

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

This solution effectively limits current supply to the display panel, reducing power consumption and maintaining image brightness while simplifying the device configuration and reducing costs by avoiding the need for complex frame memory systems.

Implementation Method 1

using a diode for current detection

Methodology Applied

Scientific EffectDiode: Diode

Implementation Method 2

using a bipolar transistor for control

Methodology Applied

Scientific EffectBipolar transistor:

Data Source

PatentUS10553155B2Current limiting circuit, display device, and current limiting method

Publication Date: 2020.02.04 MAGNOLIA BLUE CORP

AI summary

A current limiting circuit is used in a display device which includes a display panel having pixels each of which includes a light emitting element and a panel power source which supplies an application voltage to be applied to each of the light emitting elements included in the pixels. The current limiting circuit detects a supply current supplied from the panel power source to the display panel, and reduces the application voltage when a value of the supply current detected is greater than a threshold.