A choke valve is fixed to a predetermined position even after manual release, whereby an improved start and a subsequent stable operation are obtained. The conductive member is capacitively coupled to the thermal unit but free of direct electrical connection thereto. If the subject item has been previously requested, it may or may not be cached based on a comparison of durations, namely the duration of time between the current request and the previous request for the subject item and for each other item in the cache, the duration of time between the current request and the previous request for the other item. Each set of 2D images for eyeglasses includes a pair of 2D lens images, a frontal frame image, and at least one side frame image.