Play yards and methods of operating the same are disclosed. It exhibits upright and uniform growth with abundant flowers. Thus, a balanced electric current is induced. The sorption compartment has a sorption unit with the sorption drying material. A first end of the latching member is mounted in the casing. The gate widths of the first and second access nMOS transistors and those of the first and second driver nMOS transistors are equalized with each other.