A US judge on Thursday fined Taiwan\'s AU Optronics 500 million dollars and sentenced two former executives to prison for rigging prices of displays for smartphones, computers and other gadgets. \"This was a documented and far-reaching conspiracy; there is no doubt about that,\" US District Court Judge Susan Illston said while sentencing Taiwan\'s largest LCD maker and Hsuan Ben Chen and Hui Hsiung. She ordered one-time AU Optronics president Chen and former executive vice president Hsiung to each serve three years in federal prison and pay $200,000 in fines. A jury trial in San Francisco ended in March with a jury convicting AU Optronics and the men of taking part in a scheme to rig prices of thin film transistor liquid crystal (TFT-LCD) display panels from late 2001 to December in 2006. Prosecutors went on record in court calling it the \"most serious price-fixing\" case in US history and urged Illston to slam AUO with an unprecedented billion-dollar fine and imprison both men for a decade. \"We believe a $500 million fine is unable to deter the kind of conduct we see here,\" Department of Justice antitrust division trial attorney Heather Tewksbury argued during the sentencing hearing. Defense attorneys countered that the prosecution\'s recommendation was \"excessive.\" Officials said the $500 million fine matches the largest fine imposed against a company for violating the US antitrust laws.