Methods and apparatus for the recording of data to an optical media are provided. The pixel electrodes and the counter electrodes are made of a transparent conductive material, thereby increasing a transmittance and an aperture ratio. The chamber has an opening which is sealed either permanently or with a removable seal. When data of a memory cell MC is read at a bit line BL1, a reference electric potential is supplied to a bit line BL2 from the dummy cell DC. If this bump is soldered to the pad on a packaging substrate, solder gets wet in the whole region of the columnar bump upper surface and only a part of the side surface.