Patent ID: 7523241

Claim:
A hot-plug signal detecting apparatus, comprising: a control section having an AD input terminal to which a hot plug signal compliant with an HDMI standard or a DVI standard from an external device is inputted, and a hot-plug output terminal for outputting a hot plug signal in response to the inputted hot plug signal; and a transmission processing section that is connected to the hot-plug output terminal, has a hot-plug input terminal to which the hot plug signal from the hot-plug output terminal is inputted, and detects a high level or low level of the hot plug signal inputted to the hot-plug input terminal, wherein the control section comprises: a level detecting section for converting the hot plug signal inputted to the AD input terminal to a digital value, and detecting the levels of the inputted hot plug signal by comparing the digital value with a predetermined threshold value; a determination section for determining whether or not a period of one of the levels of the inputted hot plug signal is a predetermined period or more; and a hot-plug signal output section for outputting the hot plug signal of the one of the levels without changing the period of the one of the levels if the period of the one of the levels of the inputted hot plug signal is the predetermined period or more, and changing the period of the one of the levels to the predetermined period and outputting the hot plug signal of the one of the levels if the period of the one of the levels of the inputted hot plug signal is less than the predetermined period.