Scissors Gear Device

Provided is a scissors gear device having a structure which is simplified so as to reduce its overall size and thereby expand the range of application and simplify its assembly process. A scissors gear device 100 includes a main gear 101 and a sub-gear 104. The main gear 101 has three curved-surface protrusions 102 formed at a peripheral edge of one side surface thereof. The curved-surface protrusions 102 are arranged in the circumferential direction and each have an arcuate shape. The sub-gear 104 has three sloped surfaces 105 formed at a peripheral edge of its side surface facing the main gear 101. The sloped surfaces 105 are arranged in the circumferential direction. The sloped surfaces 105 are provided at positions corresponding to the curved-surface protrusions 102 formed on the side surface of the main gear 101. Each sloped surface 105 is a flat surface which extends in the circumferential direction and slopes toward the interior of the sub-gear 104 at a predetermined angle . The sub-gear 104 is pressed against the main gear 101 by a spring 107. As a result, the sub-gear 104 rotates in the circumferential direction with respect to the main gear 101, whereby a phase difference is produced between the gears.