Crown gear deceleration mechanism

A crown gear deceleration mechanism comprising:

• a stator comprising a crown gear;
• a rotor comprising another crown gear that is located so as to be inclined to the crown gear;
• and
• an output shaft coupled to the rotor,
• wherein the stator comprises a stator tooth row in which N1s stator teeth are circularly arranged,
• wherein the rotor comprises:
• a first rotor tooth row in which N1 first rotor teeth are circularly arranged;
• and
• a second rotor tooth row in which N2 second rotor teeth are circularly arranged,
• wherein the output shaft comprises an output tooth row in which N2s output teeth are circularly arranged, and
• wherein the rotor is configured to perform a precession while engaging the first rotor tooth row with the stator tooth row at places existing at both sides between which a devotion central line of the rotor intervenes,
• the rotor being configured to transmit rotation to the output shaft while engaging the second rotor tooth row with the output tooth row at the places existing at both sides between which the devotion central line intervenes,
• wherein the devotion central line is a line sea lent extending from a point at which the rotor is pressed to the stator most deeply to a point at which the rotor rises so as to be farthest from the stator,
• wherein the first rotor teeth project from the rotor in a direction opposite to a direction in which the second rotor teeth project from the rotor,
• wherein a combination of (N1−N1s, N2−N2s) is any one of (1, 1), (0, −1), (−1, 0), and (−1, −1), and
• wherein a center of the rotor is held by engagement of the first rotor tooth row with the stator tooth row and engagement of the second rotor tooth row with the output tooth row.