A projection apparatus comprises a projection control unit, power supply device and fan. Instead, embodiments of the invention can advantageously utilize existing display circuitry to provide multi-touch functionality while adding relatively little circuitry that is specific to the multi-touch functionality. The oxidized region is formed by forming a non-oxidized layer made of AlAs or the like and then oxidizing part of the non-oxidized layer at a temperature from 240\xb0 C. The etching mask has at least two openings, and areas of the two openings are different from each other. The holographic data recording apparatus do not require the replacement of the conventional conical mirrors while recording a plurality of data on a holographic medium, thereby increasing the recording speed and reducing the manufacturing cost thereof. The color converting layers and the transparent layer sandwich the transparent electrode layer with the light-emitting layer.