UV LED Backlight Heating for Avionics LCDs

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Solution Overview

Problem

Current LCDs in avionics environments require heating to function below -40°C, but existing solutions like indium-tin-oxide (ITO) heaters are expensive, reduce display transmission, and have supply chain bottlenecks, while infrared sources are inefficient and interfere with night vision goggles.

Innovation Solution

Incorporating ultraviolet (UV) light-emitting diodes (LEDs) into the backlight structure of LCDs, which operate outside the visible spectrum to heat the display without interfering with user vision, and using a temperature sensor to maintain the LCD within an operational temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If ITO heaters are used to heat LCDs, then the LCD can operate at low temperatures, but the cost increases and display transmission is reduced

Engineering Contradiction:

ImproveLCD operating temperatureVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent replaces expensive ITO heaters with inexpensive UV LED modules. The UV LEDs are mounted on standard PCBs and can be easily replaced if needed, embodying the principle of using cheap, easily replaceable components instead of expensive, difficult-to-manufacture solutions.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the heating mechanism from resistive heating (ITO) to photonic heating (UV LEDs). This parameter change in the heating method allows for cost reduction while maintaining the temperature control function, as UV LEDs are more cost-effective than ITO deposition processes.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If ITO heaters are used to heat LCDs, then the LCD can operate at low temperatures, but the supply chain becomes constrained

Engineering Contradiction:

ImproveLCD operating temperatureVSAvoidsupply chain availability

Core Design Contradiction:

TemperatureVSAdaptability or versatility

Solution Approach 1:

UV LEDs are commercially available components with established supply chains, unlike ITO which requires specialized deposition equipment and materials. This substitution improves supply chain availability and reduces manufacturing constraints.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Temperature

If IR sources are used to heat LCDs, then heating can be provided, but night vision goggles are interfered with and heat absorption is inefficient

Engineering Contradiction:

ImproveLCD heatingVSAvoidinterference with night vision

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent uses UV LEDs with specific wavelength characteristics that are absorbed locally by the LCD layers without affecting the visible spectrum. This localized spectral quality ensures heating efficiency while avoiding interference with night vision devices that operate in the infrared/visible range.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the heating wavelength from infrared to ultraviolet. This parameter change in the electromagnetic spectrum allows for efficient heat generation through LCD layer absorption while avoiding the harmful side effects of IR sources, such as night vision interference.

Inventive Principle:

Principle #35Parameter changes

4Temperature

If ITO heaters are used to heat LCDs, then the LCD can operate at low temperatures, but the device complexity increases

Engineering Contradiction:

ImproveLCD operating temperatureVSAvoidelectrical connection complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

UV LEDs mounted on standard PCBs with conventional electrical connections replace the complex ITO heater integration process. The modular UV LED assembly simplifies electrical connections and reduces device complexity compared to bonding transparent conductor heaters to the LCD stack.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 UV LED system provides efficient heating with minimal visual interference and higher efficiency compared to IR LEDs, ensuring the LCD operates effectively while reducing costs and supply chain issues.

Implementation Method 1

Ultraviolet (UV) light-emitting diodes (LEDs) are incorporated into a backlight structure

Methodology Applied

Scientific EffectLight-emitting diode (LED): Light Emitting Diode

Implementation Method 2

over 99% of the UV energy is absorbed by the LCD

Methodology Applied

Scientific EffectAbsorption of UV radiation: Absorption (EM radiation)

Data Source

PatentUS11181765B2System and method to heat LCDs using UV LEDs

Publication Date: 2021.11.23 ROCKWELL COLLINS INC

AI summary

An inexpensive system for maintaining an LCD display above an operative temperature includes ultraviolet (UV) light-emitting diodes (LEDs) incorporated into a backlight structure. The UV LEDs operate in a frequency range sufficiently removed from the visible band to not interfere with the user. A temperature sensor continuously or periodically monitors the temperature of the LCD and activates the UV LEDs to maintain the LCD in a predetermined temperature range for a desired response time.