Tsuge:By notebook standards, 13.9 mm is quite thin. But if we left the edges looking crude and boxy, the unit wouldn't look as thin as this measurement tells us it is. It would lack impact. We needed to make the thinness apparent, somehow, but with no leeway in the length and width headquarters expected, we seemed to have no recourse.
At this point, we created two mock-ups for a meeting with management to evaluate the design. One was as compact as possible, with boxy profile. The other was slightly longer and wider to demonstrate what we wanted to try—rigid arc design.
Morisawa:We can make products look thinner with tapering, metallic edges. This is effective, but it's so common that it has become rather stale. Above all, the style would be uninspiring if the surfaces you see most often when opening the lid are all flat.
There's also an opposite approach, which involves carving out the sides, so to speak. Lids designed this way resemble the capital Greek letter sigma (S) when closed. Viewed from an angle, the lids seem to float in space, which can emphasize thinness. It's a good idea, but ultimately we were unsatisfied with the appearance when open. Light reflected from the part carved away, along the edge, even makes the body look thicker.
We needed to find a new approach. After a series of attempts, we found the answer in curved edges. As with S-shaped edges, we "carve out" the sides, but the difference is that these surfaces are not simply beveled but curved. Light reflecting off flat, beveled surfaces looks rectangular, but reflections from curved surfaces look linear. This accentuates the slim body more than regular edge shapes do and subtly updates the style.
We call this new edge shape "rigid arc" design. "Rigid" because this element of design also makes the body tougher. It has higher torsional rigidity than plain, flat edges. When the body is 13.9 mm thin, you do all you can to ensure structural rigidity, because you can't add any reinforcements inside. In this sense, rigid arc design also fulfills a key structural role in this model.
But I must admit, the engineers weren't very happy about this edge shape. Special care is required to prevent the aluminum panel from warping when fabricated this way. It would take time to verify that the design was sound. Which should we prioritize—the development schedule or our ideal design? In the end, Sony management and engineers supported the rigid arc approach, and we were prepared to invest the time required to make it happen.