A working machine is provided with a revolving upperstructure, working equipment, an engine compartment, a counterweight, a muffler, and an exhaust path for releasing exhaust gas, which has been discharged from the muffler, to an outer side of the revolving upperstructure. The back light module includes a reflector, at least two light sources and at least one partition. Besides this the time dependence of the electric driving signals can be optionally modified so that with every change of the polarity of the electric driving signals, the potentials on both driving electrodes get the same value for a time, which is significantly shorter than the switching time of the LCD electrooptic switching element.