ADVANCED LINK PHOTONICS
A Leading Rugged Display Innovator
WE INNOVATE IN DISPLAY INTEGRATION
Innovative and patented LCD integration technologies
Air-gap integration, CS glass, NVIS Filters
miniLED, EMI shielding, heater
Founder of Advanced Link Photonics, Dr. Raymond Wang, has extensive academic and R&D experience in the field of optics. Based on his background and vision, he leads our team in developing and advancing display integration technologies for outdoor applications. As a result, our company excels in rugged display integration solutions for aerospace, military, defense, and industrial applications.
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Through collaboration with our customers, our engineering team has learned, developed, and implemented numerous technologies across various aspects of Display Head Assembly (DHA) integration. Over years of addressing complex customer challenges, we have come to understand that “the problems are in the details,” and have consistently demonstrated our ability to deliver effective solutions in a timely manner.
Below are examples of our innovative technologies that have been implemented to support reliable, rugged, sunlight readable DHAs solutions, including night vision, rugged touch panel, EMI, and heater, that you are using now in your systems.
Whether you need a partner for full subsystem development or additional support for your engineering team, we invite you to connect with us to innovate and solve your most challenging display requirements together.
including NVIS, rugged touch panels, EMI shielding, and heaters, currently used in your systems.
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Low Reflection Air-Gap Bonding for Sunlight Readable Feature
Thin-film transistor liquid crystal displays (TFT LCDs) became popular over cathode-ray tube (CRT) displays in the 1990s and early 2000s, following multiple technological breakthroughs contributed by various research groups in the field. The lightweight design and ease of use of TFT LCDs enabled broader adoption in outdoor applications.
However, a conventional LCD typically has a surface reflectivity of approximately 4%. Assuming incident sunlight of ~30,000 nits, the reflected luminance from the display surface can reach approximately 1,200 nits. This level of reflected brightness significantly reduces visibility, making standard LCDs difficult to use in outdoor environments.
​Achieving sunlight readability under strong outdoor illumination remains a key challenge for display integrators in this market segment. Increasing backlight brightness of and applying anti-reflection treatments to LCD surfaces are two traditional approaches to improving sunlight readability. s a result, multiple reflective interfaces are introduced within the Display Head Assembly (DHA), and total system reflectivity can easily exceed 20%, rendering the display difficult to read under strong incident sunlight. Advanced Link Photonics has innovated and introduced several patented technologies to the outdoor display market to address these challenges.
One such innovation is the passive conversion of a standard transmissive LCD into a transflective-type display (TrioLCD™), which utilizes incident sunlight as part of the effective luminance seen by the viewer. This approach significantly improves contrast under strong ambient light and enables true sunlight readability.
Another key innovation is the control of light polarization exiting the LCD to achieve total reflection control, for which ALP has been awarded a series of patents. When integrating highly reflective components—such as resistive touch panels, EMI shielding windows, and heater into a Display Head Assembly (DHA),
achieving a contrast ratio greater than 4:1 under strong incident sunlight is extremely challenging, making sunlight readability difficult to attain.
By precisely controlling the polarization of the optical path, unwanted reflections introduced by multiple functional layers within the
DHA stack can be significantly reduced, resulting in improved contrast and reliable sunlight readability.
The red curve represents the measured surface reflectance of a resistive touch panel–integrated TrioLCD (RT-TrioLCD™), which is the lowest among the configurations compared.
The same TrioLCD screen was overlaid with a standard resistive touch panel and a treated resistive touch panel using our integration approach without optical bonding-i.e., an air-gap integration. All three areas have comparable readabilities indoors. However, the readabilities under the sunlight are very different. It is worth pointing out that integration of resistive touch panels using an air-gap integration gives a superior optical performance under the sun in contrast with the traditional integration of polarized resistive touch panels, where the display area is not sunlight-readable.
Our patents also describe how this integration approach improves the viewing performance of LCDs with polarized surfaces, particularly for users wearing polarized sunglasses, which are commonly used to reduce glare from reflected sunlight.
When the polarization axis of the sunglasses is misaligned with the emitted light from the LCD (especially at off-axis viewing angles), dark or invisible zones may appear on the display. This issue can be mitigated by applying our integration approach, as illustrated in the figure to the right.
As a result, displays that would otherwise exhibit dark zones can be transformed into displays or Display Head Assemblies (or DHA) with with uniform visibility and no dark zones.
. Display with dark zones
. Display with no dark zones
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Chem. Strengthened 0.2 and 0.3 mm Glass: Rugged Touch Panel
Comparison of commercially available AR film vs our AR coating on polarizer revealed our AR coating sustains the UV exposure better.
Although our polarizer provides a harder surface for film-to-glass (FG) resistive touch panels, a plastic surface alone is insufficient for demanding field environments. Applications requiring greater durability drive the need for more scratch-resistant solutions, leading to the development of glass–glass (GG) and glass–film–glass (GFG) resistive touch panels.
ALP has further advanced GFG designs by incorporating a self-developed, chemically strengthened glass surface (0.2 mm or 0.3 mm), offering enhanced scratch and impact resistance. In internal ball-drop testing (2 oz steel ball dropped from 100 cm), our 0.3 mm chemically strengthened glass demonstrated performance comparable to Gorilla Glass and outperformed several other strengthened glass samples—only Gorilla Glass and our 0.3 mm glass survived the test.
In addition, ITO-coated glass can be further reinforced to withstand demanding military-style impact tests, such as ball-drop and boot-kick testing, enabling highly rugged touch panel solutions for harsh operating environments.
The impact resistance of an ALP rugged touch panel - constructed with strengthened 1.1 mm ITO glass and overlaid with chemically strengthened 0.3 mm glass—was compared with that of a standard glass-surface touch panel, made with commercially strengthened 1.1 mm ITO glass and a regular 0.3 mm glass overlay, using a ball-drop test.
The results are shown in the photo to the right: the touch panel on the left is ALP’s rugged design with a 0.3 mm chemically strengthened (CS) glass surface, while the panel on the right uses a standard 0.3 mm glass surface.
The results indicate that the ALP rugged touch panel withstood nearly all five drop points from a height of 100 cm, with only a minor surface dent observed at point 1 from a 90 cm drop. In contrast, the standard glass-surface touch panel exhibited breakage in both the surface glass and the ITO layer at all test points, with failure occurring at drop heights between 20 and 60 cm.
The assembly can be further reinforced by laminating a backing glass sheet to the rear of the touch panel. This enhanced structure provides high impact resistance and can withstand boot-kick testing.
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NVIS Filter for Night Vision Compatible Display
ALP has developed advanced coating processes to produce various classes of IR cut-off and NVIS filters suitable for night vision–compatible applications. We also offer filters with customized IR cut-off specifications. These filters are designed for color displays with LED backlights and provide transmission greater than 90%.
The filters can meet the NVIS radiance requirements of MIL-STD-3009 with minimal impact on color saturation and display luminance. With our coating technology, the IR cut-off band is narrow—typically less than 20 nm—ensuring high effectiveness. A representative IR cut-off filter curve is shown in the accompanying figure.
In addition to NVIS-compatible filters for display integrators, ALP also provides a range of semi-integrated NVIS-compatible LCD components. Please contact us for more details.
ALP has also recently integrated mini-LED local dimming brightness enhancement technology into our Display Head Assembly (DHA) designs. Furthermore, we have successfully developed processes to combine our NVIS technology with mini-LED local dimming backlight systems.
NVIS Parameter Measurements
Display Color T(%) u’ v’ NVIS Radiance
Color white 90 0.17 0.47 1.4E-9
Color max 92 - - 1.4E-9
Local Dimming mini-LED: Brightness Enhancement > 5,000 nits
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mini-LED Zoning
Illumination and brightness are critical factors in achieving high-quality LCD image performance. One of the most significant advancements in LCD backlighting is the introduction of mini-LED technology. The extremely small light-emitting diodes enable zoned backlighting, allowing precise control of brightness across different areas of the display.
While zoned mini-LED backlighting may appear to be a modest change, it delivers substantial improvements in image quality. In addition to color and contrast, brightness plays a crucial role in display performance. By dividing the backlight into multiple zones, local dimming becomes possible, where LEDs are dynamically controlled according to the image content. This approach enhances brightness while reducing power consumption. Depending on the dimming architecture, brightness levels of up to 10,000 nits can be achieved.
Each mini-LED backlight board can be partitioned into zones in increments up to an (1–8) × (1–8) configuration. The number of LEDs per zone determines the achievable brightness and the effectiveness of local dimming. For larger displays, up to four mini-LED boards can be connected in series to provide uniform illumination.
ALP has also developed dual-mode NVIS-compatible backlighting. In addition, local dimming reduces continuous LED operation, lowering heat generation and extending system lifespan. Contrast ratio is significantly improved, as black image regions can be rendered with minimal or no backlight illumination.
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High Efficient EMI Shilding
The development of iMesh originated from addressing a customer issue involving a polarized touch panel integrated with an etched micro-mesh, which resulted in significant optical interference. It became clear that the integration approach was not properly optimized for the application.
To resolve this interference issue, ALP developed a unique micro-mesh EMI shielding integration technology. This solution not only meets military requirements (i.e., >50 dB shielding effectiveness over 1–1,000 MHz), but also delivers superior optical performance compared to etched micro-mesh, as shown in the comparative image above.
ALP’s iMesh™ is a substrate-free, non-woven micro-mesh composed of blackened nickel (or blackened copper), designed to minimize reflectance by eliminating additional supporting layers. The mesh conductors are precisely arranged in a 90-degree orthogonal structure, which is difficult to achieve using conventional processes such as etched micro-mesh fabrication.
The key advantage of this substrate-free micro-mesh is its flexibility of integration, allowing it to be incorporated at various positions within a Display Head Assembly (DHA) without introducing unwanted optical interference.
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Speed Warming Heater
The warm-up speed of a heater is also critical in field applications. ALP’s partner has developed high-temperature soldering processes for heater wiring, enabling reliable attachment of heater leads to bus bars that withstand stringent pull-out testing.
The heater is typically terminated on opposite sides with silver or copper bus bars. A lead wire is securely soldered to the bus bar, providing a stable connection to the power supply.
The properties and heating efficiency of ALP’s LCD heater–bonded 10.4" touch screen were evaluated as an example. The test unit was placed in an environmental chamber, which was maintained at –40°C throughout the test. A thermal probe was positioned at the center of the touch panel, and temperature readings were recorded every 30 seconds.
It is often assumed that efficient heating requires a heater to be optically bonded to the LCD glass. To evaluate this, a comparative test was conducted using two 10.4" Display Head Assemblies (DHAs). In one unit, the heater was integrated using optical bonding, while in the other unit, the heater was attached to the rear of the LCD glass using tape bonding.
Both units were placed in an environmental chamber maintained at –40°C throughout the test. Chamber ventilation remained active, and a thermal sensor was positioned on the top surface of each unit.
The results indicated that there was no significant difference in warm-up speed between the bonded and non-bonded configurations. In fact, the non-bonded configuration showed comparable or slightly improved efficiency, potentially due to reduced thermal energy absorption by the bonding adhesive layer.
