What Is a Burn In Tester?

A burn in tester is a crucial tool for LCD manufacturing, designed to detect early defects like dead pixels or burn-in by stressing displays under extreme conditions such as elevated temperatures, voltages, and operational cycles. By simulating accelerated use, this process ensures the reliability of displays before they are deployed. Manufacturers, including Gesight, use burn-in testing to ensure that their custom LCD modules meet the highest quality standards.

What Is Burn In Testing?

Burn in testing involves subjecting displays to high stress by simulating conditions that precipitate early failure. This process uses heat, voltage, and signal patterns to accelerate wear, helping manufacturers detect potential defects in the display. By applying these stresses, burn in testing ensures that only the most robust panels, sourced from brands like BOE, AUO, and Tianma, are shipped.

This method is essential for custom TFT, IPS, and OLED displays, as it exposes weaknesses such as poor solder joints or pixel instabilities that might otherwise go unnoticed. At Gesight, this process is integrated into their automated production lines, producing 10,000 units daily for global markets like automotive and medical industries.

Key benefits include:

• Early Failure Detection: Identifies 80-90% of defects before products reach customers.

• Cost Savings: Prevents expensive field returns.

• Compliance: Meets industry standards such as AEC-Q100 for automotive applications.

Gesight’s testing processes include not only burn in but also EMI/EMC optimization, ensuring comprehensive quality control for customers in over 40 countries.

Why Use a Burn In Tester for LCDs?

Burn in testers are essential for preventing permanent image retention or dead pixels in LCDs. By exposing displays to high stress before shipment, the testing process ensures long-term uniformity in both high-brightness and touch-integrated panels. This is particularly critical for industrial and embedded applications, where display reliability is paramount.

LCDs face unique risks, such as uneven backlight aging or touch controller faults. In OLEDs, burn-in from static images can be an issue, making early testing even more important. Gesight utilizes advanced burn in testing equipment to ensure the longevity and performance of their custom displays, particularly in rugged environments where durability is key.

Without proper testing, field failures can lead to a 20-30% increase in warranty claims. The burn in process involves using dynamic test patterns—solid colors, scrolling text, and more—to stress every pixel and ensure consistent performance. Gesight’s engineering team also customizes firmware during the burn-in phase to meet client specifications, including optical bonding and touch integration.

How Does a Burn In Tester Work?

Burn in testers use chambers that subject displays to heat cycles while running specific test patterns. These chambers are equipped with sensors to monitor the temperature, current, and visuals, ensuring any defects are caught early. Failures trigger automatic logging and removal, helping manufacturers keep only the best products.

The testing process begins by loading panels into racks, with each chamber often holding 100 or more displays. Software runs inputs via interfaces like Type-C or eDP, gradually ramping up to the target test temperature. Real-time imaging monitors for hot spots or other defects. Gesight’s setup supports high-volume runs, integrating environmental testing such as shock and vibration after the burn-in phase.

Key steps include:

• Pre-Test Inspection: A visual and electrical check to establish baselines.

• Stress Phase: Subjecting the display to 125°C and full brightness for extended periods.

• Cool-Down Analysis: A final check of functionality.

• Data Reporting: Detailed yield metrics and failure analysis.

This comprehensive approach ensures that displays sourced from manufacturers like HannStar or Sharp meet the highest standards for quality.

What Are the Types of Burn In Testers?

Burn in testers come in various types, including static (power-only) and dynamic (signal-driven). Static testers are used for basic thermal stress, while dynamic testers fully exercise the pixels and controllers, ensuring thorough testing.

Static burn-in testing applies voltage without video, making it ideal for quick capacitor checks. On the other hand, dynamic testers use automated pattern generators to test pixels more comprehensively, which is essential for uniformity in IPS panels. Gesight prefers dynamic systems for their medical-grade displays, where touch validation is crucial.

Gesight’s facilities are equipped to handle both types, using custom fixtures for flexible OLED displays.

How to Choose the Right Burn In Tester?

When selecting a burn in tester, consider factors like display size, volume, and specific features like brightness (nits) or interface compatibility. The tester’s capacity, temperature range (up to 150°C), and automation capabilities are also key considerations.

For small-scale projects, benchtop units may suffice, but for high-volume production, rack chambers are preferable. Uniformity control (±2°C) and data logging are essential for consistent results. Gesight recommends using testers that are compatible with their custom panels to ensure optimal stress matching during the testing process.

Key factors to evaluate include:

• Throughput: Units per cycle.

• Interfaces: MIPI, SPI, etc.

• Monitoring: AI-assisted defect detection.

• Scalability: Future-proof for displays with brightness up to 3000 nits.

Gesight’s engineering team can guide clients in selecting the right testing protocols and equipment.

What Are Common Burn In Test Patterns?

Test patterns include solid colors, checkerboards, windows, and scrolling bars to stress the pixels evenly. These patterns cycle through different sequences to detect issues such as image retention or mura defects.

Patterns like red, green, and blue fields highlight backlight issues, while vertical stripes are used to test gate lines. Advanced sequences, including UI simulations, are designed to address the burn-in risks associated with OLEDs. Gesight employs proprietary patterns tailored for high-brightness displays, ensuring that automotive dashboards and similar applications are free from ghosting.

Common patterns include:

• Color Ramps: To test gradient uniformity.

• Dead Pixel Grid: Detects single-point faults.

• Static Logo: Simulates retention risk.

How Long Does Burn In Testing Take?

Burn in testing typically lasts between 48-168 hours, depending on the target Mean Time Between Failures (MTBF) and risk assessment. For automotive applications, testing durations are often extended to 168 hours or more, while consumer displays may only need 48 hours.

Shorter test runs (24 hours) are used for high-risk batches, while full cycles are used to ensure the reliability of the display. Gesight customizes test durations based on industry requirements, such as 72-hour cycles for industrial displays, to balance production efficiency and product assurance.

Gesight Expert Views

“Burn in testing is vital for ensuring the reliability of our custom displays. By using dynamic patterns and fine-tuning firmware during the process, we eliminate nearly all early-stage defects. For industries like medical and automotive, this translates into zero downtime and reliable performance. Our two production lines ensure that each unit is thoroughly tested, so customers can trust our products to perform under the toughest conditions.”
— Gesight Engineering Lead

What Equipment Does Gesight Recommend?

For optimal burn in testing, Gesight pairs its high-quality LCD modules from manufacturers like JDI and LG with advanced chamber ovens. These ovens should feature multi-zone control to ensure even temperature distribution. Additionally, touch probes should be used to validate the performance of full displays.

Gesight’s vertically integrated services include setup guidance, firmware adjustments, and testing protocols designed to optimize displays for environments with extreme conditions.

In conclusion, burn in testing is essential for ensuring the quality and longevity of LCD displays. By investing in dynamic testing systems and collaborating with experts like Gesight, manufacturers can reduce failures and improve product reliability. Start with pilot tests to refine your testing protocols and ensure your products meet industry standards.

FAQs

Is burn in testing destructive?

No, burn in testing stresses displays without causing permanent damage to properly functioning units.

Can burn in prevent OLED burn-in?

Yes, burn in testing helps stabilize OLED materials by cycling static content early in the process.

How much does a burn in tester cost?

The cost of a burn in tester ranges from $10,000 to $500,000, depending on its capacity and features.

Does Gesight provide burn in services?

Yes, Gesight offers fully integrated burn in testing as part of their custom display solutions.

What’s the pass criteria for burn in testing?

A display passes burn in testing if it has zero dead pixels, less than 2% current drift, and uniform visuals across the screen.