Gradation is improved in image formation by image-forming apparatus employing a light emitting elements such as organic light-emitting element, and image quality. The capacitor component includes at least two capacitors formed on a common dielectric substrate plate. Each Service Definition includes an input specification which identifies the address of a resource as well as the nature of the input data to be supplied to the resource with the request, and further includes an output specification which describes the nature of the output information which is supplied by the resource in response to the request. The duty cycle control circuit is configured to compare a voltage reference and a supply voltage. A tracking error signal appropriate to the optical disc to be reproduced is selected from three tracking error signals detected according to the detection signals from the photodetectors, and a tracking servo is driven according to the selected tracking error signal. The U-Bolt is tightened where the break in the exhaust pipe exists.