Patent ID: 9282208
Filing Date: 2016-03-08
CPC Classification: H04N

Claim Text:
1. An option unit electrically connected to a communication system that is controlled by a control part, the option unit comprising: an upper side signal line connecting with one of the control part and an upper option unit that is positioned closer to the control part than the option unit and electrically connected with the communication system; a lower side signal line connecting with an lower option unit that is positioned more apart from the control part than the option unit and electrically connected with the communication system; and a control circuit, the control circuit being configured to set a potential of the upper side signal line in an initial state as a first potential, and set the potential of the upper side signal line in a normal state as a second potential which is different from the first potential, and configured to control the potential of the upper side signal line to change from the second potential in response to a potential change from the second potential of the lower side signal line.