ARTICLE – Enclosures for Flat Panel Display/Computers

(Thanks to Mr. Peter Kaszycki, from Pro-Tech, for his contribution with this article. Enjoy.)  

Enclosure designs have remained virtually unchanged for a number of years. Standard NEMA ratings have been maintained depending on the environment; NEMA 12 for environments with air-borne particulants, NEMA 4 for areas subject to washdown and NEMA 4X for areas subject to washdown and corrosive agents. The style of enclosure has also remained constant, a rectangular configuration. These enclosures serve to house and protect a number of industrial devices such as PLC’s, I/O racks, controls, and CRT based computer systems.

A change however is taking place relative to enclosures for "Flat Panel" devices.

These devices included flat panel displays / computers and flat panel terminals / OITs. The change is driven by the fact that customers are demanding more from the enclosure than what is currently available. They are placing these flat panel products in areas where they would not normally put a "standard" enclosure. This means the enclosure must be small, light weight and easy to mount. They are also requiring these products to be versatile; allowing a number of operators to use them by adjusting the viewing angle, lowering the entire display or pushing it out of the way when not needed.

As a result of how customers are now using Flat Panel Products the designer of enclosures for these products must take into consideration the following factors.

The "specific’ factors / considerations include:

1. Size – these devices are being mounted in very tight areas where floor space may not be available and equipment can cause physical interference. The goal is to make the enclosure as physically small as possible to accommodate this requirement.
2. Weight – Since these units will most likely be hung from or mounted to the existing equipment or infrastructure the overall weight becomes a major factor. The lighter the unit, the easier the unit is to install in difficult locations and the simpler the mounting bracket can be.
3. Mounting – These enclosures must not only able to accept the flat panel products but must also have provisions for attaching a mounting arm or bracket. Normally, these units are not floor mounted therefore the mounting attachment must be considered and designed to support the weight.
4. Movement – Flat Panel displays / computers / terminals are used by Operators as a means of interfacing with the process they are controlling or monitoring. These Operators are typically moving around a given "work module" and there may be multiple operators that need to interface with a single flat panel product. These operators come in different heights therefore a provision to tilt and / or raise / lower the display is required. The ability to swivel the display to face the operator as they move around the work module is also a consideration. They do not always stand in the same place therefore the display should be able to follow them.
5. Ergonomics – Many "high-tech" products are now designed with an ergonomic twist. Form and function is important however "style" is now coming into play. Enclosures with rounded edges, curved tops, attractive angles, unique esthetics are becoming very popular. Customers feel if they are buying the top of the line Flat Panel Product then the enclosure should enhance the look; not take away from it. Basic rectangular boxes will not do the trick. A well engineered, ergonomic (yet functional) design will.
6. Cooling – Many enclosure manufacturers / integrators offer cooling for their enclosures. These cooling devices are typically air to air heat exchangers or conventional air conditioners. Although these cooling options provide the cooling needed they are prohibitive in size and weight. Adding one of these options to a Flat Panel Enclosure would add significantly to the overall size and could double or triple the weight. Designers must therefore consider "compact" coolers such as solid state Peltier based coolers or integrated heat sinks with internal fans / blowers for air circulation. The enclosure designer should be able to run a thermal analysis based on the internal heat load, the external maximum temperature and maximum operating temperature of the flat panel device. This will indicate what level of cooling, if any, is required.
7. Input Options – With most Flat Panel products there is also a need for an integrated keyboard or pointing device. The flat panel enclosure must have provisions for these add on attachments.
8. Cable Runs – Many Flat Panel products are designed to interface to a remote computer, PLC or network. Consideration must be given to provide usable cable entry points with proper sealing to meet the NEMA requirements. These cable connections must address the movement of the unit to prevent problems when the unit is tilted or swiveled.
9. Servicing – As with all "new" technology there may be a need for field servicing of these flat panel devices as well as "fine-tuning" from time to time. Accordingly, the enclosure design must accommodate this requirement with access doors / panels and internal sub-panels.