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How can the casing be so tough to withstand pressure, vibration, and drop impact?

Business-ruggedUnique Technology

Part 3. How can the our mobile PCs case withstand pressure, vibration, and drop impact?
Toughbook Business-rugged are lightweight but tough. Here you can find out how they came to acquire this ruggedness.

Born from user feedback: Casing with 100 kg class ruggedness

jam-packed commuter trains

Rush hour trains in Japan can be so packed that it is impossible to transfer a bag from one hand to the other.

In Japan, ruggedness means having to withstand the crushing pressure and vibration of jam-packed commuter trains.

When we went through the causes of mobile laptop damage, we found numerous instances of the LCD cracking during the journeys on rush hour trains. Consequently, Panasonic set about analyzing the kind of stress that rush hour travel imposes on a laptop being carried in a bag.Our technicians actually rode rush hour trains and monitored the forces with pressure sensors about their bodies.

Pressure sensors

Pressure sensors that were used for the measurements. After these were set in place the technician boarded the train and the distribution of pressure on the laptop inside a bag was measured.

Results clearly showed that the laptops were being subject to forces of up to 980 N (100 kgf).* So, one of the targets for new Toughbook Business-rugged was the ability to withstand, from the top and bottom, a pressure of 100 kgf. However, because it's a mobile PC, this doesn't mean that it can be heavy or the body can be big in order to achieve ruggedness. It is necessary to have a design that combines both lightness and ruggedness.

*1 kgf is the force generated by a body with a mass of 1 kg accelerating at 9.8 m/sec2. The letter f after kg stands for force. Meanwhile, the SI (International System of Units) newton unit (N) refers to the force generated by a body with a mass of 1 kg accelerating at 1 m/sec2. In effect, 1 kgf = 9.8 N.

Magnesium alloy casing for laptop computers

To provide casing that is light but tough, magnesium alloy was selected as the material.
Magnesium alloy has the following characteristics.

Lightness – The specific gravity of pure magnesium is two thirds that of aluminum, one third that of titanium, and less than one quarter that of iron.

Strength – The specific strength* is about the same as aluminum and compares favorably with iron.
(* Specific strength is material strength divided by weight per cubic unit (density). The greater the specific strength, the lighter and stronger is the substance.)

Magnesium materials also have a high work hardening ratio* and are less susceptible than aluminum to physical impact deformation.
(* The work hardening ratio is a measure of material hardness after bending and pounding (plastic deformation) processes.)

These two major advantages have made magnesium alloy the material of choice for cell phones and digital cameras, for use in rigorous applications, such as in aircraft construction, and for other objects for which light weight and strength are priorities.

Other characteristics useful for laptop computers

Good electromagnetic wave characteristics
Magnesium provides insulation against certain electromagnetic wave. So it also serves to protect precise and complex computer parts. At the same time it also, of course, prevents the escape of electromagnetic wave from computers. (Be aware that it cannot absolutely block, or completely protect against, electromagnetic wave.)

Good heat dissipation
Because it heats up and cools down easily, magnesium alloy helps to disperse the heat generated inside a computer.

Only 5% of the energy required to make magnesium alloy is required for recycling scrap materials.

While magnesium alloy possesses these superior properties, when strong force is applied to flat sections, they are prone to bending. This was a drawback.

Inspiration from car design! Make the lid like a car hood.

“How to take advantage of the light weight and strength of magnesium alloy?” One engineer, who had pondered this question long and hard, suddenly saw the answer when he looked at a car stopped on the road. Strength had been added to the gentle curves of its large hood by some pressed lines. These were the answer to the problem.

It's easy to see which is weaker!

Imagine a sheet of paper. If you push down on one end, the sheet will easily bend. If, however, you put folds in the same piece of paper, it will not bend. In the same way, magnesium alloy sheet can be made dramatically stronger simply by putting some small steps in it.

In this way, the Toughbook Business-rugged acquired its distinctive contoured LCD rear cover, or lid, design. The early models had simple lines, but the results of continued analysis enabled, by modifying the pressed lines with subtle curves, even greater strength against pressure.

Annular pipe structure provides strength around the LCD

Contouring is not the only secret behind the strength of the top plate. Comparing mobile laptops, Panasonic top plates have a higher profile than those of other makers. This extra height is one of the secrets of strength.
We have been able to artfully incorporate a pipe-like structure all around the outer edges of the Panasonic laptop top plate. The annular pipe structure braces the top plate against pressure and prevents twisting, thus protecting the LCD from pressure.

Box-like structure designed to brace the outer edge

Meanwhile, the LCD panel is not completely fixed to the lid. Supported by dampers, the panel is supported in a floating design. Even if the lid were to be twisted, the LCD would not break easily.
Furthermore, in the latest CF-W7 and CF-T7 a cradled structure has been adopted for the LCD display. Protrusions at either corner of the LCD display correspond to recesses at the corners of the palm rest. When the display is closed, these engage so that the computer casing cradles the LCD and decreases the danger of damage from impact after falling.

Floating structure to protect the main board if the chassis is distorted

A floating design has also been applied within the casing of the laptop.
When the substrate and LCD are installed, rather than being fixed to the four corners of the casing, they are left floating by partial fixing and are supported by cushioning material. Consequently, even if the casing is put under pressure, the resultant distortion does not so easily affect the interior parts.

In this way, a number of combined design strategies have ensured that Toughbook Business-rugged are both light and tough.

For further information about our products, how to purchase them and more, please visit the website of your region.

Specification and configuration may vary depending on country. Accessories may vary depending on your mobile PC configuration.
Specifications subject to change without notice.
Consult a Panasonic sales office near you for more details and availability of integrated options.

Global Home Business > You are here:PC Top > containsUnique Technology > containsPart 3.