Method for eliminating strong ambient light in aircraft cockpits

#The present invention relates to display devices, and in particular to the use of two polarizers to ensure visibility of the display in strong ambient light.

#Display devices, such as liquid crystal displays (LCDs) and cathode ray tubes (CRTs) are used to display data to users. Bright environments, such as cockpits of aircraft often contain such display devices. In some environments, the visibility of information is critical. In aircraft, good visibility of the information on display devices can be critical to safe operation of the aircraft.

#Prior solutions for minimizing the effect of cockpit ambient light include application of various films or coatings only to display surfaces. Coatings such as AR, AG, and linear or circular polarizers work under low or moderate ambient light conditions, but fail at higher levels of illuminance, such as 10K foot candles.

#FIG. 1 is a block representation of a pair of polarizing sheets in a cockpit having a display device.

#FIG. 2 is a block representation of an alternative embodiment of a cockpit having a display device.

#In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following description is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.

#FIG. 1 is a block diagram of a cockpit having a light source 110, such as a window, and a display device 120, which receives ambient light from light source 110. In prior systems, the ambient light would overwhelm the visibility of information viewable on the display device. In the present invention, a first sheet of polarizing material 130, represented by an arrow is attached to the window 110. The arrow on material 130 also approximately represents the pass axis orientation of the polarizing material. A second sheet of polarizing material 140, represented by an arrow is attached to the display screen 120. The arrow on material 140 represents the pass axis orientation of the polarizing material, and is projected substantially perpendicular or orthogonal to projected light from the pass axis of material 130. The actual angle of the pass axis of each polarizing material is dependent on the geometry of the cockpit.

#Each side window proximate an environment containing a display is provided with a sheet of polarizing material having a pass axis orientation projected approximately perpendicular to that of the polarization on the display. The polarizer in one embodiment is a high-transmittance, high-efficiency polarizer and is available from several manufacturers, such as Polaroid and Nitto. The polarizer also contains a pressure sensitive adhesive to enable easy attachment to the surface. In further embodiments, an electro optical device provides the proper polarization, such as a switchable polarizing window.