Speed reducer

A gear mechanism, comprising:

• a first shaft;
• a second shaft disposed at an angle with the first shaft;
• a third shaft having an axis extending in a same direction as the second shaft;
• a first gear group including a plurality of first gears that transmit rotation of the first shaft to the second shaft;
• and
• a second gear group including a plurality of second gears that transmit rotation of the second shaft to the third shaft, a first second gear being situated closest to the second shaft among the plurality of second gears, a last second gear being situated closest to the third shaft among the plurality of second gears, and a straight line that connects a rotation center of the first second gear and a rotation center of the last second gear intersecting with the first shaft when viewed in a direction along the second shaft.

A speed reducer, comprising:

• a first shaft;
• a second shaft disposed at an angle with the first shaft;
• a first gear group including a plurality of first gears that transmit rotation of the first shaft to the second shaft;
• and
• a second gear group including a plurality of second gears that transmit, to an output side, rotation of the second shaft transmitted from the first shaft, a first second gear being situated closest to the second shaft among the plurality of second gears, a last second gear being situated closest to the output side among the plurality of second gears, and a straight line that connects a rotation center of the first second gear and a rotation center of the last second gear form an angle with the first shaft when viewed in a direction along the second shaft;
• a rotary drive source for rotationally driving the first shaft;
• and
• a speed reducing unit serving as the output side that outputs rotation of the last second gear.