The troubled life of Patent No. 6,456,841

Tracing the tortured legal trail of a simple smartphone patent. Takeshi Tomimori, an engineer at Mitsubishi Electric Corp., in Tokyo, had an idea. What if you could alert a cellphone user of incoming messages by displaying an icon on the screen? He worked out the details for what Mitsubishi's lawyers called, in their 1999 filing, a "Mobile Communication Apparatus Notifying User of Reproduction Waiting Information Effectively." Three years and three months later, the U.S. Patent and Trademark Office awarded Tomimori and his employer Patent No. 6,456,841. Let's call it Icon, for short.