Light emitting roller for roller skates

A light emitting roller for roller skates, comprising:

• a roller body having a center axle hole for mounting on a wheel axle, an annular groove around said center axle hole at an outer side, a battery chamber and two opposite through holes at said annular groove;
• an annular circuit board mounted within said annular groove on said roller, said annular circuit board comprising a plurality of light emitting elements controlled to emit light through the through holes on said roller body, an automatic switch, an opening, two contact metal plates at two opposite sides of said opening, and a battery cell connected between said contact metal plates and mounted within said battery chamber on said roller to provide electric power supply to said light emitting elements through said automatic switch;
• and
• an annular cap mounted within said annular groove on said roller to hold down said annular circuit board.