A safety device limits the pressure in an axial-piston compressor with variable piston displacement. According to an exemplary embodiment, the configuration secures a semiconductor device such that a die of the device is exposed to an electrically charged environment and electrically conductive terminals of the device are isolated from the electrically charged environment. First, the nozzle row is moved to positions \u201ca\u201d and \u201cb\u201d by main scanning in the X direction to enhance wettability of the surface of the areas and then main scanning is executed at each of the positions while successively moving the nozzle row to positions \u201cc\u201d through \u201ck\u201d by sub-scanning, thereby repeatedly discharging ink in the same portion of the areas. In addition to permitting direct comparison of qualitative and quantitative protein content of tumor cells and normal cells from the same tissue sample, the methods also allow for investigation of protein characteristics of tumor cells, such as binding ability and amino acid sequence, and differential expression of proteins in particular cell populations in response to drug treatment. Users are provided with an opportunity to view channel information before setting channels as favorites.