Patent ID: 7274360

Claim:
A multiple control system for controlling a display unit provided in a composite electronic apparatus having a plurality of electronic devices incorporated therein, the multiple control system comprising: a display driver adapted to drive the display unit; a first controller adapted to control one of the electronic devices and having a output selection terminal and a three-state output terminal connected to the display driver via a serial communication line; and a second controller adapted to control another electronic device and having a output selection terminal connected to the output selection terminal of the first controller and a three-state output terminal connected to the display driver via a serial communication line in parallel with the first controller, wherein when the first controller controls the display driver, the first controller outputs a first control signal to the second controller, and the second controller puts the three-state output terminal thereof in a high impedance state when the first control signal is received, and wherein when the first controller does not control the display driver, the first controller outputs a second control signal to the second controller and puts the three-state output terminal thereof in a high impedance state, and the second controller controls the display driver when the second control signal is received.