A water redispersible polymer powder may be produced by drying an aqueous mixture of a water insoluble film-forming polymer and a colloidal stabilizer comprising a chelating agent to obtain a water redispersible polymer powder, where the amount of chelating agent is at least 0. The optical axis center of the projection optical system is set to a position different from that of the center of the projection area onto which the pattern is projected. The cameras are configured and arranged to obtain images to be combined to generate a bird’s-eye image to monitor a periphery of the dump truck. A switch circuit is configured to provide a negative voltage to one of the first address decoder and the second address decoder on the basis of block address information that specifies an address included in one of the first memory block and the second memory block. Then, the integrated contacts are collectively inserted into a shell.