Safety helmet with alarm means for calling for help

A safety helmet comprising an outer shell, and inner shell mounted inside said outer shell, said inner shell having a plurality of air vents, a fan mounted on said outer shell for causing currents of air for ventilation, an alarm device mounted on said outer shell at a rear side thereof, and battery power supply which provides electric energy to said fan and said alarm device, said alarm device comprising a buzzer, first switch means, second switch means, an alarm control circuit controlled by said second switch means to produce an audio alarm signal through said buzzer, and at least one signal lamp controlled by said first switch means to produce a visual signal, said at least one signal lamp and said alarm control circuit being connected in parallel to said first switch means, said alarm control circuit being connected in series to said first switch means through said second switch means, said first switch means being switched on and said second switch means being switched off when the user puts the safety helmet on the head, said second switch means being automatically switched on when tilted with the safety helmet over a predetermined angle, or automatically switched off when maintained with the safety helmet in horizontal.