A rear projection display device includes an image generator, a reflector, a screen and a light shield disposed between the reflector and the screen. The lever includes two pads for engaging with the foot pedals. The percentage of nitrogen partial flow in the mixture of gases is adjusted so as to result in a layer of tantalum nitride with a nitrogen content of at least 30%. In operation, the interface creates and exports to the data store structured data representations, which correspond to versions of the local file system, as well as the actual file system data that these structured data representations represent. As it is quite rare that the total signal intensity becomes zero, occurrence of an operation error due to division by the value of zero can be restrained.