A differential amplifier circuit includes a first differential transistor pair, a second differential transistor pair, an adder section and an amplifying unit. When this method is used, a data signal side driving circuit and a gate signal side driving circuit are formed with TFTs that use a silicon film having a peculiar crystal structure and exhibit an extremely high operation speed. The knockout plug is detachably coupled to the tapered-threaded knockout, with the seal providing an environmental barrier between interior and exterior portions of the electrical enclosure. The shutter member closes another part of the first opening in the restricted state so as to close the first opening in concert with the disc tray, and in the disc access state the shutter member is caused to slide by the disc tray so as to be capable of opening the other part of the first opening. The subcarriers can be further pre-equalized by dividing the subcarrier signal respectively by the sum of the squared magnitude of the frequency channel characteristics of all subcarrier signals or a frequency characteristic of the selected antenna element.