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76 cm free fall testing

Business-ruggedUnique Technology

Part 1. The secret behind a design that's tough enough to pass 76 cm free fall testing*1
Recently, the new line-up of TOUGHBOOK Business-rugged computers was announced. Here, you can read the first installment in an informative series of articles dealing with separate aspects of the superior technology that Panasonic has incorporated in these latest models.

What better computer to use in the Bullet Train? TOUGHBOOK Business-rugged laptops come out on top for light weight, battery powerduration, and toughness.

You can slip it in your bag. You can carry it with ease. Then, on the move, a laptop lets you do the same work as in the office. For success, one tool is indispensable to business professionals in Japan. Everyone needs a mobile computer that is lightweight, has lasting battery power and, on top of that, is tough. For people who are determined to succeed, TOUGHBOOK Business-rugged laptops are a popular choice. This is shown in the No. 1 ranking in the “Nikkei Personal Computing*2 007 Overall Computer Customer Satisfaction Survey.” Besides that, you frequently see people with TOUGHBOOK Business-rugged laptops on the Bullet Train and, they say, at academic conferences, too.

* A respected computer journal in Japan.

The reasons why so many users rate TOUGHBOOK Business-rugged (known as “Let’snote” in Japan) laptops so highly are light weight, ranging from about 1.3 kg to 1.6 kg, computing performance on a par with desktop machines, and battery power duration. Then there is ‘toughness.’ Even though your laptop may be light and have lasting battery power, if it isn’t robust, it may not work after getting knocked or rattled, or break when you drop it on your way somewhere, or cause you to lose important data if water gets spilled on it at the office. You can’t call it a mobile computer, if it’s not ‘tough.’

Anticipating actual conditions of use Survival of 76 cm drop is standard for all models. Reasons for Mobile Computers Malfunctions graph (Source) IDC Whitepaper, Ruggedised PCs Today's Mobile Computing World. Sponsored by Panasonic. Includes content from IDC Notebook Study 2005.

Through over ten years experience in producing light mobile computers, the Panasonic personal computer development team became strongly aware of the importance of 'toughness.' That's why they introduced know-how from TOUGHBOOK Fully-rugged laptops, which are designed with 'toughness' as the top priority. They succeeded in developing a "light but strong" body. The high level of customer satisfaction and large share of the Japanese market is a measure of their success.

Now, in the new, recently launched 7 series, all models in the range have received “76 cm free fall testing”*1, as well as “Spill resistance keyboard”.*2 Now, in the following explanation of “76 cm free fall testing,” you can discover the secret of more-advanced tough design.

*1 Carried out in Panasonic technical research lab. Dropped on to bottom (in operation-mode).
*2 Spill resistance applies to all of the keyboard. It does not apply to the side panel, battery section, speakers, and DVD drive when it is open (Y7 and W7). The spill-resistant performance of the product does not guarantee that it will be free from damage or malfunction. If water is spilled onto it, be sure to have it repaired. (Note that a fee will be charged for this repair service.)

First, an explanation of how we dealt with fall impact issues

These days, many makers publish figures for toughness. But the values are meaningless if they do not reflect conditions typically encountered in the real world.

As you can see in the graph on the right, fall during carriage is the most common and fall during operation is the third most common reason for laptop computer malfunction. The word ‘fall,’ however, may refer to significantly different things: depending on the fall height and conditions of impact, the force of impact on the body will be different. So at Panasonic we envisaged falls from different heights and set numerical targets for survivability from different drop heights. As you can see in the table below, we carry out free fall tests from three heights.

Height (cm) Real-life conditions
10–15 The drop height when you somewhat carelessly toss an object onto desktop or other surface.
30 A drop from this height causes about the same force of impact as a computer receives inside a bag that is chucked on to a desktop.
70–76 This is typically the height that the computer falls if knocked off a desktop or dropped while being carried.

Long-standing expertise with ruggedization used in designing hard drive impact resistance

Shock-absorbing pads protect HDD from impact

Previous TOUGHBOOK Business-rugged models (CF-W5, T5, Y5) were designed and tested to survive drops, when not operating, from 30 cm on to 26 surfaces or edges, and from 10 cm (onto the bottom side only) while operating. In the new 7 series models, the free fall test height for operating computers has jumped to 76 cm (on to bottom side only).

This achievement was enabled both by strengthening the body and by improving dampening technology to protect the hard disk.

Shock wave at 76cm Drop
Degree of Shock when dropped on the bottom surface

Business-rugged TOUGHBOOK laptops have the same kind of dampening cushions that is used to protect the hard drives of fully ruggedized Fully-rugged models. After trying out different cushioning materials and optimizing their form, it was possible to achieve designs that could withstand falls from 76 cm.

A mass of dampening know-how

To achieve high impact resistance, it is not good enough to merely wrap cushioning materials around the hard drive. During dampening design, parameters have to be worked out for hardness of the materials, thickness, and surface area. It is particularly important to be aware that when the surface area of impact is smaller, the applied energy gets focused. In other words, the smaller the area, the more it concentrates the force of impact.
No matter how soft the cushioning material is, if the area is too extensive, it has no dampening effect. More compact areas absorb impact more effectively. If the force of impact is not localized, the coefficient of restitution rises. When this happens, rather than the initial impact, the larger ensuing secondary (rebound) wave causes damage.
Moreover, rather than affecting just the hard drive, the force of impact is received by the whole product. Consequently, depending on the shape and size of the product, the way the vibration wave impacts on the hard drive changes. So, if pads of the same type and size of cushioning material are located in the same places in different models, it is not always possible to rely on their effectiveness.
The type and size of cushioning material and where it’s placed, and various other factors, such as the general rigidity of the whole body, how the impact is transmitted and the drop height and body’s angle of impact, have to be taken into consideration when designing the cushioning material. In the new models, when you see the cushioning material that has been placed under the hard disk, it may look like it has simply been stuck there. It is visible. But the size, shape, and resiliency all result from experience with TOUGHBOOK Fully-rugged laptops. In other words, what you are seeing is a collection of know-how.

Why vibration sensors are not used

As a means of protecting the hard drive, vibration sensors have appeared in some mobile computers. When the sensor detects vibration, the magnetic head of the hard disk is withdrawn. At Panasonic, we also looked at the feasibility of this method but rejected it.
One reason was the rate of erroneous detection.
You have to be able to use your mobile computer. You need to be able to use it comfortably even during travel in a vehicle. If vibration sensors are used, they are prone to erroneous detection even from innocuous vibrations in a train. The hard drive will periodically stop while you are working. Although you brought your laptop to work on the move, your efficiency suffers from the stuttering operation. This is not the way to go. Nor does reducing the sensor sensitivity work. When the sensor is needed, because it can no longer respond quickly enough, the magnetic head cannot be withdrawn in time. Accidental knocks and drops happen before you know it.
The biggest issue is dealing with 30 cm drops. In fact, sensors cannot effectively detect falls up to about 30 cm. That’s why we use only cushioning to absorb impact. After looking at the pros and cons, rather than depending on sensors, we came to the conclusion that dampening was more effective at physically protecting the hard disk from impact.
As a result, we chose a low-tech solution. Dampening proved to be the more effective way of protecting your data.

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.

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