A light-emitting warning device of a safety helmet, including a helmet main body, a light guide element and a light source control mechanism. Inversion of received control codewords indicates polarity inversion somewhere along the link, enabling automatic polarity correction to be applied. The valve can be a passive bi-directional valve, such as a dome valve, or a passive unidirectional valve. Also, by obtaining the data of the amount of torsion of a cantilever with the shape data of the pattern, a profile error of the side wall portion by the adhesion is corrected by the obtained data of the amount of torsion.