Patent ID: 7631623

Claim:
A valve timing controller for an internal combustion engine, the valve timing controller adjusting a valve timing of at least one of an intake valve and an exhaust valve by driving an electric motor in a normal rotation direction or a reverse rotation direction, comprising: a driving circuit for driving the electric motor by applying electricity to the electric motor according to an inputted control signal and for generating a rotation-direction signal indicating a rotation direction of the electric motor while receiving a power source voltage; a control circuit for outputting the control signal which is generated according to the rotation-direction signal; and a signal line for transmitting the rotation-direction signal from the driving circuit to the control circuit, wherein the driving circuit outputs a high-level-voltage signal as the rotation-direction signal indicating the normal rotation direction and a low-level-voltage signal as the rotation-direction signal indicating the reverse rotation direction, and when the power source voltage falls lower than or equal to a permissible value, a voltage level of the signal line is maintained at high level; the control circuit includes a pull-up resistor for pulling-up the signal line, the driving circuit includes a signal generating part which generates a driving signal from the power source voltage, the signal generating part sets the voltage level of the driving signal at low-level when the power source voltage is higher than the permissible value and the rotation direction is the normal rotation direction, the signal generating part sets the voltage level of the driving signal at high-level when the power source voltage is higher than the permissible value and the rotation direction is the reverse rotation direction, the signal generating part sets the voltage level of the driving signal at low-level regardless of the rotation direction when the power source voltage is lower than or equal to the permissible value, and the driving circuit includes a switching device which turns off based on the driving signal of low-level such that the signal line is brought to a non-active condition, and turns on based on the driving signal of high-level such that the signal line is brought to an active condition.