An electric heater includes at least one heater element which is adapted to emit electromagnetic radiation having a first wavelength. A sliding assembly has one member fixed to the crown’s inside and a second slidably attached to the first as a extension to the brim. For overcurrent protection, a current detect resistor is connected in series with the active switch for providing an uncorrected current detect signal indicative of the current flowing through the active switch. The first sidelight source is disposed at one end of the light-guide plate.