Drive transmission device

A drive transmission device comprising:

• a rotatable driving member to which a driving force is transmitted from a driving source;
• a first gear configured to be rotated by receiving the driving force from said rotatable driving member;
• and
• a second gear configured to rotate a driven member by being rotated by rotation of said first gear,
• wherein said first gear includes a driving portion consisting of a plurality of first teeth and configured to drive said second gear, a convex portion having an arcuate shape concentric with a rotation center of said first gear and an engaging portion located at a position shifted from said convex portion with respect to a rotational axis direction of said first gear,
• wherein said second gear includes a driven portion consisting of a plurality of second teeth engageable with associated first teeth and configured to be driven by said driving portion, a contact portion configured to contact said convex portion, and a portion-to-be-engaged engageable with said engaging portion and located at a position shifted from said contact portion with respect to a rotational axis direction of said second gear,
• wherein a distance between said portion-to-be-engaged and an adjacent upstream second tooth of said driven portion with respect to a rotational direction of said second gear is larger than a distance between adjacent second teeth of said driven portion, and
• wherein in a state in which said convex portion slides on said contact portion so as not to rotate said second gear when said first gear rotates, said engaging portion engages with said portion-to-be-engaged such that said contact portion separates from said convex portion, and said driving portion engages with said driven portion so as to transmit the driving force from said first gear to said second gear.