Pixel Driver Redundancy for Display Manufacturing Yield

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Solution Overview

Problem

Conventional display technologies face challenges in manufacturing yield due to defects in pixel driver chips, which are difficult to test at the wafer scale, leading to integration of defective chips into display panels and resulting in reduced yield and increased costs.

Innovation Solution

Implementing redundancy schemes in pixel driver chip configurations, including driver terminal switches and redundant pixel driver circuits, to selectively operate primary and redundant strings of LEDs, allowing for increased manufacturing yield and reduced silicon or chip count, while maintaining acceptable defect rates and expanding LED matrix size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If pixel driver chips are integrated into display panels without wafer-scale testing, then manufacturing cost is reduced and integration is simplified, but manufacturing yield decreases due to defective chips

Engineering Contradiction:

Improveintegration simplicityVSAvoidmanufacturing yield

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent implements preliminary testing and selection of pixel driver chips at the wafer scale before integration into display panels. This preliminary action identifies and isolates defective chips early in the manufacturing process, preventing them from reducing overall display panel yield while maintaining simple integration procedures for subsequent steps.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If redundant pixel driver circuits are added to increase manufacturing yield, then defect mitigation is improved, but device complexity and silicon area increase

Engineering Contradiction:

Improvedefect mitigationVSAvoidchip configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the pixel driver chip into multiple independent driver circuits, each capable of driving specific regions of the LED matrix. This segmentation allows individual defective drivers to be isolated and deactivated while maintaining functionality of remaining segments, providing redundancy without requiring complete duplicate circuits across the entire chip.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements local redundancy where specific driver circuits or regions are duplicated only where needed based on defect patterns. Rather than uniformly adding redundancy across the entire chip, the system provides targeted redundancy in affected areas while maintaining minimal complexity in defect-free regions.

Inventive Principle:

Principle #3Local quality

3Productivity

If redundant pixel driver circuits are implemented to increase manufacturing yield, then yield is improved, but the number of silicon or pixel driver chips required increases

Engineering Contradiction:

Improvemanufacturing yieldVSAvoidsilicon or chip count

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent merges multiple driver circuits within a single pixel driver chip, allowing one chip to contain both primary and redundant driver capabilities. This consolidation provides the benefits of redundancy while reducing the total number of separate chips required, as each chip serves multiple functional roles including backup capacity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12183285B2Pixel driver redundancy schemes

Publication Date: 2024.12.31 APPLE INC

AI summary

Display panel redundancy schemes and redundancy building blocks are described. In an embodiment, pixel driver chips are connected to both primary and redundant strings of LEDs within a local passive matrix, and driver terminal switches within the pixel driver chip are used to select either the primary or redundant strings of LEDs.