International Journal of Computer Applications (0975 – 8887) Volume 122 – No.3, July 2015 13 Analysis of Displays Attributes for use in Avionics Head up Displays Pooja Verma Vinod Karar Vandana Niranjan Surender Singh Saini Department of ECE Department of ODS Department of ECE Department of ODS IGDTUW, Delhi CSIR-CSIO, Chandigarh IGDTUW, Delhi CSIR-CSIO, Chandigarh ABSTRACT Modern avionics provide a comprehensive human-machine interaction. The modern electronic displays are the key components of any glass cockpit based aircraft employing the state of art avionics and are being increasingly used due to two main reasons: firstly, the continuous advancements and improvements in the electronic display technologies, and second being the progressive changes in the onboard data distributing and processing methods in both military and civil aircraft. In this article we have discussed several electronic display devices and relevant technologies for avionics display use especially with reference to the head-up displays. These display technologies have been analysed with reference to the avionics display requirements and vital parameters like size, resolution, brightness, flicker, shades of grey, contrast, color, power consumption, etc. General Terms Display Technologies, Avionics Display, Head Up Display Keywords Cathode Ray Tube, Display Attributes, Head Up Display, Display Writing Methods, Display Technologies. 1. INTRODUCTION Avionics is the heart of modern aircraft, and many function of avionics play an important role in both civil as well as military aircraft. A variety of cockpit displays based on various display technologies along with Mission Computers (MC) and Display Processors (DP) provide a great human- machine interaction. While the MC or DP process the sensors data and provide two types of information to the pilot: One, the data on the demands of aircraft such as pressure, temperature, airspeed, fuel state etc., and second, the data due to the relative situation of aircraft to the outside world such as attitude, navigational position of the aircraft, etc. Keeping these basic functions of the cockpit display functions in mind, variety of cockpit display employed in the modern aircraft such as Multi Functional Displays (MFD), See-through Displays like Head Up Display (HUD) and Helmet Mounted Display (HMD), Moving Map Displays (MMD), Electronic Flight Instrument System (EFIS), etc. have been conceptualized and then custom built as per the application, requirements of the pilot and the aircraft platform [1]-[2]. 2. DISCUSSION ON DISPLAY TECHNOLOGIES SUITABLE FOR AIRCRAFT COCKPIT DISPLAYS The light emitting diodes (LEDs) are semiconductor based devices comprising of p-n junction diode made from III-V group element. These may include gallium, indium, arsenic, aluminum, phosphorous, or antimony. When the junction is forward bias it emits light due to electron-hole recombination. These devices are used for backlighting the LCD panels and also used in the LED based navigational, landing and taxi lighting system of aircrafts. However, they are not suitable for direct application as a display device in a cockpit display [1], [3]. The liquid crystal display (LCD) is a non-emissive display technology based on the principle of dynamic scattering of light. Mostly used structure of LCD is twisted nematic. They can result in high contrast ratio coupled with lesser operational voltage requirement and reduced power consumption. However, this technology suffers from the disadvantage such as poor intrinsic viewing angle, backlighting requirements, temperature and sunlight dependent performance, etc. [3]-[5]. The electroluminescent display (ELD) emits light when the electric field is applied across polycrystalline phosphorous surface. This technology can be built to be rugged with large intrinsic viewing angle, higher operational speed, better brightness and contrast. However, it has inherent highly non- linear voltage-current characteristics, higher operational voltages and low efficiency hence not preferred for avionics use except for aircraft internal lighting purpose but not as a direct display element [3], [6]. The plasma displays are manufactured by sandwiching many cells between two glass plates. By applying electric current to each cell the gas (plasma) is excited which leads to emission of UV rays. This technology is realized in large display sizes which are greater than 32 inches, with high resolution and brightness, excellent contrast and color gamut, large angle of view and higher operational speed. However, its limited operational life and availability in higher sizes only makes it unfit for use in aircraft [3], [7]. The organic light emitting diode (OLED) is a type of LED composed of a film of organic compounds and uses the principle of electroluminance. It overcomes many limitations of LCD like availability in range of sizes including smaller sizes, relatively large viewing angle, high resolution and speed, good color gamut, etc.; however it has got life cycle issues [1] ,[3]. The cathode ray tubes (CRT) were excessively used during the Second World War in the military aircrafts for radar displays to generate alphanumeric characters and symbols. After 1967 many display technologies have been developed with the intention to replace CRT due to its bulky size and higher power consumption, however, for avionic HUD use no technology could fulfill the aircraft requirement like high brightness, contrast ratio and sun-readability, large viewing angle, etc. Hence various types of CRT based on display surface - flat or curved, based on size - range of sizes, based on color - monochrome or color, based on types of phosphor, etc. have been developed over the years [2].