Drive transmission device and image forming apparatus

A drive transmission device that transmits driving force of a motor to a roller via a plurality of drive trains, the drive transmission device comprising:

• a controller;
• a first drive train including a one-way clutch;
• and
• a second drive train that is different from the first drive train and includes an electromagnetic clutch, wherein
• the first drive train receives the driving force from the motor and transmits the driving force to the second drive train,
• the second drive train transmits the driving force from the first drive train to the roller,
• the controller switches a rotational speed of the roller by switching on/off the electromagnetic clutch,
• the first drive train includes a first gear, a second gear, and a rotary shaft to which the first gear and the second gear are connected via the one-way clutch,
• the first gear and the second gear each have teeth on an outer circumferential surface thereof,
• the number of the teeth of the first gear is a first teeth number and the number of the teeth of the second gear is a second teeth number that is different from the first teeth number,
• the second drive train includes a third gear, a fourth gear, and a rotary shaft to which the third gear and the fourth gear are connected via the electromagnetic clutch,
• the third gear engages the first gear,
• the third gear and the fourth gear each have teeth on an outer circumferential surface thereof, and
• the number of the teeth of the third gear is a third teeth number and the number of the teeth of the fourth gear is a fourth teeth number that is different from the third teeth number.