Rugged Tablet Computers - Lessons Learned And Design Responses

Since the days of the ancient Egyptians, paper has been the medium of choice for capturing data. Today, paper – in the form of notebooks, maps and photographs, to name a few – is being rapidly supplanted by digital technology. The computer has moved from the office into the field. While rugged mobile computers were once used primarily by military personnel and focused applications in the commercial and industrial markets, today’s rugged computer is for people who perform normal job functions in demanding environments.

High and Low Temperatures

Mobile devices are subjected to a much broader range of temperatures, ranging from winter nights in Minnesota to summer days in Arizona. These extremes are quite different from the office. Sound thermal design practices not only address electronic components, but also the liquid crystal display (LCD), battery, and spinning storage media. In addition, overall thermal design establishes a “cold boot” lower limit and maximum hot operation. The ability of a computer to operate at high and low temperatures also depends in part on the selection of materials and how they relate to other materials in environments that can cause differential expansion and contraction.

Shock and Vibration

Mobile devices are subjected to a broad range of intentional and non-intentional usage environments not present with office equipment. Non-intentional shock includes dropping and sliding off surfaces, while intentional shocks occur through operations such as a vehicle backing up to a loading dock, a rail car engaging, or a tow truck winch operating. Vibration, on the other hand, is specific to the vehicle or stationary equipment on which the device is mounted. While most applications are typified by random vibration, in some cases, such as onboard a ship, there is an overlay of a strong periodic vibrating component induced by engines.