Some people get revelations in the shower. Others solve puzzles in their dreams. Yousuke Yamada, a lead engineer for the Japanese office-equipment and camera maker Ricoh Co. Ltd., gets his best ideas on Tokyo commuter trains. "I cannot create an idea at my desk," he says. "I like to walk around a crowded train, where nobody disturbs me."
Over the past three years, while his fellow commuters jostled for space or scanned the morning paper, Yamada, 55, devoted his four-hour daily commute to a higher cause--dreaming up the next great consumer gadget. In 1997 Ricoh president Masamitsu Sakurai commissioned Yamada to...