A method and apparatus for reducing the processing rate when performing chip-level equalization in a code division multiple access receiver which includes an equalizer filter. In one embodiment, a sender transfers an encrypted version of a file to someone who wishes to receive it. The phosphor thin film comprises a matrix material containing as a main component at least one compound selected from an alkaline earth thioaluminate, an alkaline earth thiogallate and an alkaline earth thioindate, and an rare earth element as a luminescent center, and the dielectric thin film comprises an alkaline earth oxide.