The Selection of the base AMLCD is not a trivial matter. The AMLCD must not only meet the mechanical mounting requirements of the application, be of such construction to support the Ruggedization process, as well as possessing the necessary inherent design attributes that are not subject to modification. The pixel matrix of display must be appropriate for the application in terms of spatial resolution both for moving images and graphics. Optimization matching of platform sensor characteristics to the pixel matrix and host interface compatibility are important especially in legacy applications. The AMLCD cell structure must have sufficient response time to minimize motion artifacts and provide adequate contrast in all ambient conditions within a defined viewing cone. Knowledge of supply issues and trends in AMLCD manufacture is used to minimize obsolesence problems.

The typical AMLCD will require some level of ruggedization for use in defense of aerospace applications.
This will range from the bonding of optically processed contrast enhancement cover glass and rear heating elements to the removal and attachment of flex bond drivers and polarization layers. Each application will have its specific level of ruggedization and methods used as required. The ruggedization process must accommodate temperature extremes both operating and storage over repeated cycles, extreme vibration and shock levels and high altitude. The optical processes must minimize front surface and inner structure reflections while optimizing contrast and color rendition. ADT has perfected methods, procedures and materials in the ruggedization process in applications from fixed and rotary wing to tracked vehicles.

Part of the ruggedization process typically will include the design of a replacement backlight system capable of providing at least a 3:1 contrast ratio in 10,000 fc diffuse plus 2000 fL spectral ambient illumination with a dynamic range capable of dimming to 0.01 fL with a spectral response compatible with use of a NVIS equipment. Such a system must be reliable through redundancy, power efficient, sustainable, and capable of meeting the environmental temperature, vibration and altitude requirements.

ADT has developed several designs capable of providing the above characteristics both for monochrome NVIS Green A and B, and NVIS color applications. The typical design relies upon the use of multiple cold cathode fluorescent lamps and inverters in an edge lighting arrangement. This design avoids the all or nothing failure mode. Full color presentation is always available and lamp time is minimized. The design compensates for lamp aging and performance over temperature. A display is, of course, an optical system from backlight through AMLCD to the optical cover glass. It must be looked as an interactive optical system in order to optimize performance while minimizing power usage, size, weight, and heat generation.

Since an AMLCD is a progressively scan, fixed pixel matrix and fixed pixel size device, the video input must be either compatible with the selected AMLCD pixel or processed accordingly. Further, since a typical display or military application may interface to multiple video sources, having various signal types, the display must be capable of processing all video sources as required with regards to the AMLCD matrix. The input video may require scaling either up or down, aspect ratio conversion, selectable horizontal or vertical scaling, frame rate conversion, gamma correction, color space conversion and de-interlacing.

ADT has developed several designs capable of providing the above processes including the de-interlacing of input video without loss of spatial resolution of the generation of temporal artifacts. The resultant progressively scanned image retains the individual field timing and spatial relationships as the input source video. Targets can still be tracked and distinguished to the distance the operator was capable of using a CRT without the generation of ghost images. This capability is of particular importance when incorporating AMLCD technology into legacy RS-170 and RS-343 video systems.

Certain Applications are best served through the use of commercially available board level products. ADT has, when appropriate, successfully used COTS devices after being processed by ADT to meet the application requirements. This approach can save development costs and time to deployment. ADT has used extensively PC104 based products in its display systems mated with ADT custom board level products as required. VME is another board level format when space permits for either ruggedization or the integration of military grade VME products into the display system.

The use of COTS board level products is particularly desirable when software tools, application products and systems are already available. These COTS software products generally will require the integration of a PC based for windows family compatible subsystem within the display. ADT has successfully fielded these systems on all platform types.

When COTS board level products are used, an appropriate operating system must be selected that supports the application software and the board level driver requirements. ADT has successfully integrated windows NT embedded OS into selected display systems. For an application configured with dual 1553 interfaces, dual video camera capture capability, quad RS-422, 20 on-board relays and digital control I/Os, P5 CPU, dual drive 2D/3D accelerator, PCMCIA, and SSD, the target OS is on the order of 20 MB. For every high reliability application the use of memory protected OS is recommended such as the Greehills Integrity product combined with the Seaweed Systems OpenGL product.

ADT designs and manufactures illuminated front panel assemblies and bezel key assemblies. Individual key cap and rockers are also designed and manufactured by ADT. These assemblies typically will integrate NVIS compatible transilluminated key caps, dead front legends LED message arrays, rotary and rocker controls, access doors, timers and clocks. Typical construction is of Aluminum for ruggedness and prevention of light leaks through abrasion. Bezel key arrays can electrically interface directly with the display or with the host system as an independent interface, such as RS-232, 422, or PS/2. Certain front panel or bezel designs may integrate the AMLCD or cover glass assembly and system mounting plate as the particular application requires for space, mounting methods, shock and vibration.