A light-emitting module includes: (a) a liquid-crystal module containing a pair of transparent substrates and a liquid-crystal layer disposed between the pair of transparent substrates; (b) a first light-emitting diode (LED) component disposed on a first side of the liquid-crystal module; (c) a first transparent cover plate over the first LED component such that the first LED component is sandwiched between the liquid-crystal module and the first transparent cover plate; and (d) a control circuit configured to control an on/off frequency of the liquid-crystal module and a light-emitting frequency of the first LED component in such a manner that the light emitted from the first LED component is synchronously shielded by the liquid-crystal module, wherein the light is emitted from a side opposite to the liquid-crystal module.