Thursday, November 1, 2012

Mounting an LCD or OLED

This is the first in a series of notes on mounting LCDs and OLEDs. This installment will cover the basics; next time we'll walk through the process of using Front Panel Express to design and manufacture a simple LCD/OLED mounting panel.

Our displays end up in applications ranging from scuba rebreathers to mining gear to car-door testers to (not kidding) bedpan washers. This makes it tough to recommend a one-size-fits-all answer to mounting and enclosure issues. But there are a few constants:

Don't go naked. Displays must be mounted behind a protective, transparent window (examples) to prevent damage from curious fingers, electrostatic discharge, dirt, solvents and moisture. You've seen a lot of projects online that leave the display naked and exposed to the world, but chances are the sole user of those devices is the maker. Other users cannot be expected to be as careful of or kind to a display as the person who bought it (and would have to replace it if it gets broken).

Use the mounting holes. And only the mounting holes. We've seen displays ruined by being glued, taped, or even force-fit into panel cutouts. Don't do it. The sturdy-looking metal frame that surrounds the display screen houses a fine-pitch elastomeric connector. It's a miracle of precise assembly that can be wrecked by mechanical or chemical malpractice. On a related note, don't try to save a trip to the hardware store by enlarging the mounting holes to fit the hardware you have on hand.

Give it space. There's a strong temptation to position the screen right up against the panel in which it's mounted. Some displays, typically those with touch screens, are designed for this. But the 'readout'-style displays we sell are extremely allergic to pressure on the screen, and are easily damaged by electrostatic discharge. Further, if the metal frame of the display contacts a metal mounting panel, you can create a ground path that you didn't intend, but sure will have to troubleshoot.

Treat it gently. Protect the display from shock, vibration, excessive heat and cold, and especially condensation.

Bezel? We don't need no stinking bezel. Many users associate display mounting with the B-word, bezel. They're puzzled that they can't find some kind of plastic picture frame to put in front of the display. That is, until they look closely at commercial gear that incorporates small displays; almost all of it uses the overlay technique that covers the screen with a self-adhesive sheet of transparent plastic (usually polycarbonate). Overlays are inexpensive, customizable and very effective.

Avoid the pitfalls--we'll help! We're putting together this series of notes to help you make a neat, professional, reliable and durable mounting arrangement for your display. The plan is to cover both commercial and hobbyist approaches ranging from handtools to CNC services. In researching this material, we've had some pleasant surprises, particularly in the increasing ease and declining cost of computer-controlled machining operations. Next installment, we'll show you a custom-machined mounting panel that we designed using free software and cost us less than $50.

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