Novel 1-aryl-4-thiotriazines I . The mask circuit supplies a video signal to each of the pixels in a partial display area selected based on a display area selection signal, and prevents the supply of the video signal to each of the pixels in a background display area. The limited number of usable channel candidates are then used to perform intermittent signal reception, thereby shortening the searching time cycle of such intermittent reception within a standby period, thus lessening the startup time from the standby state between the wireless video transmission and reception devices and also reducing standby power thereof. The bottom portion includes a front support portion that supports a front end portion of the shock absorber. The flat stop surface is adapted to engage with the alignment portion to limit the rotational movement of the ball valve.