TFT LCD Image Retention (Ghosting)

Causes, Risk Scenarios, and Selection Considerations

---

1. Phenomenon Overview (Engineering Perspective)

Image retention, commonly referred to as ghosting, describes a condition where faint traces of previously displayed content remain visible after the image has changed.

In industrial TFT LCD applications, ghosting is typically not a product defect, but a display behavior resulting from the combined effect of panel characteristics, driving method, operating environment, and application usage pattern.
Understanding this distinction is critical when evaluating display suitability for long-term or mission-critical deployments.

---

2. Ghosting Is Not a Single Issue

From an engineering standpoint, image retention observed in TFT LCDs can originate from different mechanisms. Identifying the type helps determine whether the risk can be reduced through selection or integration decisions.

Common Types of Image Retention in TFT LCDs

Temporary Image Retention

• Often related to liquid crystal response characteristics
• Influenced by temperature and image transition behavior
• Typically reversible when operating conditions change

Driving or Bias-Related Retention

• Associated with mismatched driving voltages, Vcom settings, or timing parameters
• Frequently observed when the LCD panel and driver board are not electrically optimized as a pair
• May persist until electrical conditions are corrected

Long-Term Degradation Related Retention

• Caused by prolonged exposure to static, high-contrast images over extended service life
• Accelerated by elevated operating temperatures
• Usually irreversible and considered a lifecycle-related phenomenon

---

3. Engineering Factors Influencing Ghosting Risk

Not all contributing factors are equally controllable. From a system design perspective, it is important to distinguish between design-controllable parameters そして application-driven constraints.

Factor	Engineering Control	Notes
LCD response time	高い	Evaluated during panel selection
Driver board matching	高い	Electrical compatibility is critical
Static UI ratio	ミディアム	Strongly tied to application design
Operating temperature	ミディアム	System-level thermal management
Panel aging	低い	Inherent lifecycle behavior

Ghosting risk is rarely attributable to a single parameter; it is usually the result of multiple marginal conditions stacking together.

---

4. Application Risk Scenarios

Ghosting likelihood varies significantly depending on how the display is used in the field.

Higher-Risk Application Scenarios

• 24/7 operation with minimal content variation
• Static UI layouts with fixed icons or indicators
• High-contrast graphics displayed for long durations
• Elevated ambient or enclosure temperatures
• No scheduled display sleep or refresh behavior

Lower-Risk Application Scenarios

• Periodically changing or dynamic content
• Video or animated graphical interfaces
• Systems with scheduled sleep, dimming, or refresh cycles
• Well-controlled thermal environments

Understanding where an application falls within this spectrum is often more important than focusing on panel specifications alone.

---

5. Design & Selection Considerations to Reduce Risk

Rather than relying on post-deployment mitigation, ghosting risk should be evaluated during the selection and integration phase.

主な考慮事項は以下の通り：

• Confirming panel suitability for long-duration static display use
• Ensuring electrical and timing compatibility between LCD panel and driver board
• Reviewing operating temperature margins against real enclosure conditions
• Considering UI refresh strategies at the system or software level
• Accounting for long-term aging effects in lifecycle planning

No TFT LCD can guarantee zero image retention under all conditions; the goal is risk control, not absolute elimination.

---

6. Engineering Insight from Field Deployments

In industrial projects, image retention is most often observed when application behavior, electrical driving, and thermal conditions are evaluated independently rather than as a system.

During display selection and integration reviews, these factors are typically assessed together to determine long-term suitability and operational risk—especially for 24/7 HMI, kiosk, and unattended systems.

---

7. When to Review Your Display Configuration

A technical review is recommended if your application involves:

• Long-term static or semi-static UI elements
• Continuous operation without display rest periods
• Elevated operating temperatures
• Non-standard driver boards or customized driving conditions

---

エンジニアリング・レビューのエントリー・ポイント

Not sure if your application is suitable for long-term static display operation?
Share your operating conditions, UI behavior, and environment details with our engineering team for a feasibility and risk review.

---

This content is intended as an engineering reference for display behavior evaluation and should be considered in the context of complete system design.