Patent attributes
A lamp overload detection/modulation circuit including a microcontroller unit for detecting rectangular wave signal reflective of the power used by the lamp load and pulse width signal of AC power. The positive bandwidths of the two signals are compared with a predetermined full-load value. In the case that the positive bandwidths of the two signals are both larger than the full-load value, it is indicated that the lamp load is under an overload condition. Under such circumstance, the microcontroller unit controls a lamp load driving unit to change driving manner and lower the power used by the lamp load to a value within a nominal range. Then the lamp load automatically restores to the full-load state. Accordingly, the lamp is protected from long-term overload condition.
