| 摘要 |
PROBLEM TO BE SOLVED: To stably communicate without requiring a complicated circuit even when a nonstandard cable is used. SOLUTION: A signal attenuation determination unit determines a signal attenuation of a signal in accordance with types of a cable and a personal computer that a user inputs, and when the attenuation is equal to or larger than reference attenuation, a power supply IC lowers a voltage to be applied to a control IC. Even if the signal is subjected to a limit line 31 or 32 which is at an original level since the attenuation is equal to or larger than the reference attenuation, the limit lines 31 and 32 decrease in level as the power supply voltage of the control IC drops, so that the signal is not subjected to the limit lines 31 and 32, and normal communication is performed even if the signal attenuation is equal to or larger the reference attenuation. COPYRIGHT: (C)2011,JPO&INPIT
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