Micro-LED Failure Detection and Resistor Shunting for Display Uniformity
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Solution Overview
Problem
Micro-LEDs in electronic displays can fail, causing current to be drawn away from functioning LEDs, resulting in perceivable visual image artifacts such as darker columns due to reduced luminance.
Innovation Solution
A sensing scheme identifies failed micro-LEDs using forward bias and a compensation scheme adjusts current flow or image data to mitigate the effects of failed LEDs, including shunting current around the failed LED with a defined resistor and applying gain masks or setting image data to gray level 0 to reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a micro-LED fails and continues to draw current, then the failed micro-LED remains electrically active, but the luminance of other micro-LEDs on the same anode decreases causing visual artifacts
Solution Approach 1:
The patent applies preliminary action by performing sensing operations during manufacturing or field operation to identify failed micro-LEDs before they cause significant display artifacts. The system proactively detects failed micro-LEDs by applying forward bias and measuring current, then pre-configures compensation measures such as adjusting drive signals or isolating the failed component, thereby preventing luminance degradation before it becomes visually perceptible.
2Device complexity
If sensing circuitry is integrated with touch sensors, then device complexity is reduced, but the sensing precision for detecting failed micro-LEDs may be compromised
Solution Approach 1:
The patent applies segmentation by separating the sensing operation into distinct phases: a sensing phase where forward bias is applied to detect failed micro-LEDs, and a display phase where normal operation occurs. The sensing circuitry uses different operational modes - applying a forward bias voltage during sensing and a different voltage during display - allowing the same hardware to perform both functions while maintaining detection precision through specialized sensing protocols.
3Reliability
If compensation schemes adjust current flow to mitigate failed micro-LEDs, then visual artifacts are reduced, but the overall current management complexity increases
Solution Approach 1:
The patent applies feedback by implementing a closed-loop system where sensing circuitry continuously monitors micro-LED status by measuring current flow under forward bias conditions. When a failed micro-LED is detected, the system provides feedback to adjust drive signals in real-time, compensating for the failed component's current draw. This feedback mechanism maintains display uniformity by dynamically adapting current distribution based on actual micro-LED performance.
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 reduces or eliminates perceivable visual image artifacts by compensating for failed micro-LEDs, maintaining desired luminance levels and reducing further degradation.
Implementation Method 1
The sensing circuitry may cause a first switch to open to stop current flow from the micro-driver and cause a second switch to close to provide a bias voltage to drive a respective micro-LED for testing. If the micro-LED is partially short-circuited, then the sensing circuitry may determine that the micro-LED may be malfunctioning.
Implementation Method 2
A shunt switch with a defined resistor may be coupled to the micro-LEDs. The shunt switch may include a defined resistor having a defined value that therefore draws a defined short circuit current. If one of the micro-LEDs may be identified as a failed micro-LED, the respective shunt switch may close to cause the current to be shunted around the failed micro-LED.
Data Source
AI summary
A display system may include a plurality of light emitting diodes to emit light, where each of the light emitting diodes are connected in parallel and a plurality of first switches respectively coupled to the plurality of light emitting diodes. A first switch of the plurality of first switches is coupled in parallel to a first light emitting diode. The first switch may short the first light emitting diode of the plurality of light emitting diodes through a defined resistor having a defined value that therefore draws a defined short circuit current.