Abstract: A spark plug assembly has a spark plug with an inner conductor, an outer conductor and an intervening insulator. A quick-change adapter is receivable in the spark plug hole of an internal combustion engine, and the spark plug is removably received in the adapter. Gas seal rings may be provided about the spark plug outer surface. Indexing marks may be provided on the adapter and the spark plug to angularly align the spark plug conductor gap to a desired angular position. The spark plug may be formed with an extension.

Abstract: A light control device comprises a liquid crystal cell 12, and a pulse control unit 62 or 64 wherein when a transmittance of light transmitted from said liquid crystal element is changed from an actual light transmittance to an intended light transmittance, the pulse control unit is able to insert beforehand a drive pulse for control corresponding to a minimum light transmittance or a maximum light transmittance, at least, prior to application of a drive pulse corresponding to the intended light transmittance. A method of driving the light control device is also described wherein the light control device is driven by use of the drive pulse for control, along with a pickup device wherein the light control device is arranged in a light path of a pickup system.