Patent ID: 7362796

Claim:
A signal relay circuit for relaying a digital signal transmitted from a signal generating unit to a signal receiving unit and having a first potential level and a second potential level that is higher than said first potential level, said circuit comprising: a capacitor connected between said signal generating unit and said signal receiving unit for receiving digital signal, eliminating a DC component from said digital signal as received, and outputting the digital signal, from which said DC component is eliminated, to said signal receiving unit as a restored digital signal; a first resistor having one terminal connected to a power supply which pulls up the potential of said restored digital signal as received from said capacitor and the other terminal connected to a relay point between said capacitor and said signal receiving unit, and having a resistance value with which a current flowing through said first resistor is smaller than an output current of said first potential level from said signal generating unit; and a second resistor having one terminal connected to said relay point and the other terminal connected to a ground potential, and having a resistance value with which a current flowing through said second resistor is smaller than an output current from said signal generating unit having said second potential level.