For Kazuo Hirai, creating Sony Corp.'s flagship smartphone was too important to be left to the company's mobile phone experts.

Taking aim at a $310 billion market dominated by Samsung Electronics Co.'s Galaxy and Apple Inc.'s iPhone, Sony's chief executive officer sent dozens of his company's camera engineers to its phone division last year to give the Xperia Z handset advanced photography capabilities.

It was a big change for a company whose units haven't been used to collaborating on their thousands of consumer products.