Wheel train mechanism, gear box, driving device, and electronic apparatus
In a wheel train mechanism, a first speed reduction gear, a second speed reduction gear, a third speed reduction gear, a fourth speed reduction gear and an output gear are all made of a resin material. The third speed reduction gear and the fourth speed reduction gear are disposed at a rear stage of the second speed reduction gear and made of a material having rigidity higher than that of the first speed reduction gear and the second speed reduction gear. The output gear is disposed at a rear stage of the fourth speed reduction gear and is made of a material having rigidity higher than that of the fourth speed reduction gear.
1. A wheel train mechanism comprising:
a plurality of gears that is configured to transmit a power of an actuator to an output device,
wherein the plurality of gears are all made of a resin material, and
wherein the plurality of gears includes
a first gear,
a second gear which is disposed on a rear stage of the first gear and made of a material having rigidity higher than that of the first gear, and
a third gear which is disposed on a rear stage of the second gear and made of a material having rigidity higher than that of the second gear,
wherein the third gear constitutes a final stage gear among the plurality of gears,
wherein the final stage gear has an output shaft which is provided with a fourth gear, and
wherein the fourth gear is connected to the output device, and has a module larger than that of the final stage gear.
2. The wheel train mechanism according to claim 1 ,
wherein the second gear constitutes a front stage gear which is connected to a front stage of the final stage gear among the plurality of gears.
3. The wheel train mechanism according to claim 1 ,
wherein the fourth gear is made of a material having rigidity lower than that of the third gear.
4. The wheel train mechanism according to claim 1 ,
wherein, in gears adjacent to each other among the plurality of gears, a face width of a rear gear, which is positioned more toward a rear stage side than a front gear which is positioned toward the actuator side, is smaller than a face width of the front gear, and
wherein, when the power is transmitted, in a plane direction orthogonal to a direction of supporting shafts rotatably supporting the plurality of gears, the face width of the rear gear always overlaps the face width of the front gear.
5. A gear box comprising:
the wheel train mechanism according to claim 1 ; and
a casing that accommodates the wheel train mechanism.
6. The gear box according to claim 5 ,
wherein a supporting shaft rotatably supporting the third gear is provided in the casing, and
wherein the supporting shaft is made of a metal material.
7. A driving device comprising:
the gear box according to claim 5 ; and
the actuator that is connected to the wheel train mechanism.
8. The driving device according to claim 7 ,
wherein the actuator has an input gear which meshes with a foremost stage gear among the plurality of gears, and
wherein the foremost stage gear is made of a material having rigidity higher than that of the input gear.
9. An electronic apparatus comprising:
the driving device according to claim 8 ; and
the output device that is connected to the driving device and driven by the driving device.