A horizontal scanning period is divided into n parts, so that horizontal scanning can be performed times in one frame period. It is an object of the present invention to suppress the effect of the change in current value of a light emitting element due to the changes of environment temperature and changes with time. These pivoting movements of the aligning members enable the work piece to be aligned during rotary operations. In this manner, when the client sends a request for any of these related beans, they can be supplied from the cache rather than making another call to the database.