Patent ID: 8031571

Claim:
A signal drive apparatus comprising: a first buffer circuit that receives an amplified electrical signal from a first light signal from a first input terminal; a second buffer circuit that receives an amplified electrical signal from a second light signal from a second input terminal; a control circuit for causing one of said first and second buffer circuits to be in an operating state and causing an output stage of the other buffer circuit to be in an idle state of a high impedance, so as to output a changeover control signal which picks up either said first or said second light signal; a voltage changeover circuit for causing any one of the output stages of said first and the second buffer circuits to be in the idle state and supplying a transistor constituting said output stage with a bias voltage equal to or less than a withstand voltage of said transistor; and a flexible substrate that receives said electrical signal from said first buffer circuit when the control circuit causes said first buffer circuit to be in an operating state or receives said electrical signal from said second buffer circuit when the control circuit causes said second buffer circuit to be in an operating state, wherein the first input terminal is connected to a non-inverting input terminal of the first buffer circuit, and wherein an output of the first buffer circuit is connectively fed back to an inverting input terminal located on the first buffer circuit, directly connected to an output terminal, and directly connected to an output of the second buffer circuit, and wherein the second input terminal is connected to a non-inverting input terminal of the second buffer circuit, and wherein the output of the second buffer circuit is connectively fed back to an inverting input terminal located on the second buffer circuit, directly connected to the output terminal, and directly connected to the output of the first buffer circuit.