Flange Concept for Front Surface Mounting of LCD

Front Surface Mounting of an LCD For Avionics Applications using a Flange*

by Lawrence E. Tannas, Jr.

Orange, California



A liquid crystal display (LCD) is mounted on the front surface of a panel where the LCD may cover the mounting holes and access holes used to attach the instrument on the back of the panel. The LCD would normally be an integral part of the instrument and be mounted to the panel as a single assembly. In this innovation, the LCD is a stand-alone separate assembly mounted on the front surface. The LCD assembly with flange can be low profile including the bezel. The FLANGE* is uniquely designed to facility these features while meeting ARINC 408A Specification.


Normally, a display mounted on an avionics panel is designed to maximize image area while minimizing panel area dedicated to the display and the instrument assembly. The instrument assembly is typically attached to the panel with three or four peripheral screws with a viewing hole near the center. Typically the display cannot protrude forward from the panel more than an inch so as not to interfere with or block the view and operation of other functions of the panel. The LCD must be made small enough to fit in the instrument assembly and is a considerable limitation in the application of LCDs to avionics and cost of a custom designed LCD.


A flange has been invented to attach the LCD to the front surface of the panel. The LCD is mounted via the flange. The electrical connection can be completed through a central, coincident hole in the flange and panel. The flange has a recess to hold the LCD, designed to enable the LCD to overlap one or more of the attachment screws and the panel hole. The LCD has a means to be positioned and attached to the flange. Once the LCD rests in the flange, now attached to the panel front, an additional assembly called the “bezel” is attached to the flang. The bezel is designed to cover the LCD, masking inactive areas around the perimeter while allowing the active image area to be seen through a viewing hole. The bezel may also have other holes for the attachment of switches and control knobs.

Using the flange, the assembly of the LCD, bezel, switches and knobs may be completed in the following sequence.

1. Instrument assembly without display and flange are attached to back and front of the panel typically using four screws at four corners;

2. The LCD is electrically connected to the instrument assembly using an electrical cable through coincident holes in the panel and flange;

3. The LCD is inserted into a recess in the flange designed to accurately position and hold the LCD. Other mechanical and electrical connections may be made at this time, anticipating the attachment of the bezel;

4. The bezel is attached to the flange using screws as attachment means dedicated to attach the bezel so as to secure the LCD in place with the proper orientation and proper viewing port to observe the image area of the LCD; The assembly is disassembled in the reverse order. An exploded view of the complete assembly is shown below. The instrument assembly and interconnecting electrical cable are not shown and mechanical switches and knobs attached via the bezel are not shown. The LCD may be resized to minimize the required size of the flange and optimize the use of the available panel area. The electrical connection to the avionics or electronics must be completed before the display and bezel are attached to the flange covering the access hole through the panel to the instrument assembly.

* Patent Applied For Tannas@ 2014


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