Reducer

1. A reducer comprising:

a casing;

an input shaft; and

a planetary gear speed reduction mechanism having an internal gear, an external gear which internally meshes with the internal gear, and a swing body which makes one of the internal gear and the external gear rotate on its axis with an oscillating movement in accordance with a rotation of the input shaft, the casing containing the input shaft and the planetary gear speed reduction mechanism, the one of the gears serving as an output shaft or a member integrated with the one of the gears serving as the output shaft, wherein the output shaft carries both a component of the oscillating movement and rotational movement, and wherein the output shaft rotates on its axis to take out a rotation component with the oscillating movement to outside the casing.

2. The reducer according to claim 1 , wherein

the output shaft is not supported by any bearing that is configured to coaxially align the center of the output shaft.

3. The reducer according to claim 1 , wherein

the one of the gears is the external gear, and a through hole is formed along a plane of the casing, the plane being orthogonal to the center of the input shaft.

4. The reducer according to claim 3 , wherein

the internal gear has teeth, a part of the teeth of the internal gear is omitted, and the through hole is formed in the omitted portion.

5. A reducer comprising:

a casing;

a first shaft;

a planetary gear speed reduction mechanism having an internal gear, an external gear which internally meshes with the internal gear, and a swing body which makes one of the internal gear and the external gear rotate on its axis with an oscillating movement in accordance with a rotation of the first shaft, the casing containing the first shaft and the planetary gear speed reduction mechanism;

a second shaft disposed outside of the casing in parallel with the first shaft; and

a transmission disposed between the one of the gears and the second shaft, which transmits a rotating movement of the one of the gears to a side of the second shaft and absorbs the oscillating movement of the one of the gears.

6. A reducer comprising:

a casing;

a first shaft;

a planetary gear speed reduction mechanism having an internal gear, an external gear which internally meshes with the internal gear, and a swing body which makes one of the internal gear and the external gear rotate on its axis with an oscillating movement in accordance with a rotation of the first shaft;

a second shaft disposed in parallel with the first shaft; and

a transmission disposed between the one of the gears and the second shaft, which transmits a rotating movement of the one of the gears to the second shaft and absorbs the oscillating movement of the one of the gears, the casing containing the first shaft, the planetary gear speed reduction mechanism, the second shaft, and the transmission.

7. The reducer according to any one of claims 1 to 6 , wherein

a part or the whole of the casing serves as a structure of a host machine, in which the reducer is installed.

8. The reducer according to claim 5 or 6 , wherein the transmission comprises:

a driving section rotating integrally with the one of the gears;

a driven section formed in the second shaft; and

a strip-shaped transmission member wound between the driving section and the driven section.

9. The reducer according to claim 8 , wherein

a driving groove section is formed in the one of the gears as the driving section, and the driving groove section rotates integrally with the one of the gears.

10. The reducer according to claim 5 or 6 , wherein the transmission comprises:

a driving gear rotating integrally with the one of the gears; and

a driven gear disposed in the second shaft, and engaged with the driving gear in such a manner as to enable to absorb the oscillating movement of the one of the gears.

11. A reducer for driving a slidable member moving in a predetermined direction, the reducer comprising:

a first shaft; and

a planetary gear speed reduction mechanism having an internal gear, an external gear which internally meshes with the internal gear, and a swing body which makes one of the internal gear and the external gear rotate on its axis with an oscillating movement in accordance with a rotation of the first shaft;

a second shaft disposed in parallel with the first shaft; and

a transmission disposed between the one of the gears and the second shaft, which transmits a rotating movement of the one of the gears to a side of the second shaft and absorbs the oscillating movement of the one of the gears, wherein the slidable member is driven in conjunction with a movement of the transmission or a rotation of the second shaft.

12. The reducer according to claim 11 , wherein

the slidable member being a target to be driven serves as the transmission.

13. A reducer for driving a joint of an industrial robot, said reducer comprising:

a casing:

a first shaft;

a planetary gear speed reduction mechanism having an internal gear, an external gear which internally meshes with the internal gear, and a swing body which makes one of the internal gear and the external gear rotate on its axis with an oscillating movement in accordance with a rotation of the first shaft;

a second shaft disposed in parallel with the first shaft;

a transmission disposed between the one of the gears and the second shaft, which transmits a rotating movement of the one of the gears to the second shaft and absorbs the oscillating movement of the one of the gears, wherein

the joint is driven in conjunction with a movement of the transmission or a rotation of said second shaft.