In September 2007, during a lawsuit with patent holding company Burst.com, Apple drew attention to a patent for a similar device that was developed in 1979. Kane Kramer applied for a UK patent for his design of a "plastic music box" in 1981, which he called the IXI. He was unable to secure funding to renew the US$120,000 worldwide patent, so it lapsed and Kramer never profited from his idea.
In what year did Kane Kramer apply for his patent?
{'text': '1981', 'answer_start': 236}