Field sequential color display technology uses the temporal properties of the human visual system in order to build a full colored frame by time sequential additive synthesis of a given number of sub-frames, e.g. the standard red, green, and blue primaries, or up to six primaries such as in the latest improvement made with color wheels. Because field sequential color display can exhibit a disturbing visual artifact called the rainbow effect or color breakup effect, we set up a psychophysical experiment to evaluate in an easy way the visual comfort of the standard observer according to the technology of color wheel used versus several significant parameters that must be taken into account when considering this effect. The study is an attempt to better understand the perception of the rainbow effect and the way to reduce it. It also provides data, results and discussion about color wheels, and their latest improvements.