Combined gear, lens adjustment mechanism, and electronic device

1. A combined gear comprising a pair of gears having a same tooth profile and rotatably combined in a state wherein rotation centers of the gears are coincident,

wherein one of said pair of gears comprises an elastic displacement portion that is biased in a direction of rotating an other gear with respect to said one gear,

wherein said other gear comprises a positioning portion that positions said other gear with respect to said one gear, and said elastic displacement portion contacts said positioning portion,

wherein said elastic displacement includes an arm arcuately extending circumferentially of said one gear,

wherein said positioning portion includes a contact surface against which said arm of said elastic displacement portion makes contact, and said contact surface is formed to incline in a direction in which a normal line of a reference pitch circle of said other gear extends,

wherein the arm comprises a cylindrical contact pin at an end of the arm,

wherein said contact surface comprises a flat surface, and

wherein the cylindrical contact pin makes contact with said contact surface in a state of point contact.

2. The combined gear according to claim 1 , wherein a shaft portion that contacts said contact surface extends from said arm in parallel with an axial direction of said one gear, and

said contact surface is formed in parallel with an axial direction of said other gear.

3. The combined gear according to claim 2 , wherein contact points between said shaft portion of said arm and said contact surface are provided with a center of rotation of said gears therebetween, and said contact points are positioned on a line passing through said center of rotation.

4. A lens adjustment mechanism, comprising:

a combined gear according to claim 3 ; and

a rotation detection element that detects an amount of a rotation of said combined gear rotated with a movement of a lens in an optical axis direction.

5. A lens adjustment mechanism, comprising:

a combined gear according to claim 2 ; and

a rotation detection element that detects an amount of a rotation of said combined gear rotated with a movement of a lens in an optical axis direction.

6. A lens adjustment mechanism, comprising:

a combined gear according to claim 1 ; and

a rotation detection element that detects an amount of a rotation of said combined gear rotated with a movement of a lens in an optical axis direction.

7. An electronic apparatus comprising a lens adjustment mechanism according to claim 6 .

8. A lens adjustment mechanism, comprising:

a combined gear according to claim 1 ; and

a rotation detection element that detects an amount of a rotation of said combined gear rotated with a movement of a lens in an optical axis direction.

9. The combined gear according to claim 1 , further comprising another elastic displacement portion that is biased in the direction of rotating the other gear with respect to said one gear, said another elastic displacement portion being positioned opposite to the elastic displacement portion with respect to the rotation centers of gears.

10. The combined gear according to claim 9 , further comprising another positioning portion that positions said other gear with respect to said one gear, said another elastic displacement portion contacting said another positioning portion, and said another positioning portion being positioned opposite to the positioning portion with respect to the rotation centers of gears.

11. The combined gear according to claim 1 , wherein said cylindrical contact pin as a shaft portion is integrally formed at the end of the arm.

12. The combined gear according to claim 11 , wherein said cylindrical contact pin extends in parallel with an axial direction of said one gear and contacts said other gear.

13. The combined gear according to claim 11 , wherein the positioning portion comprises an opening portion in which said cylindrical contact pin on the arm of the elastic displacement portion is inserted, and

wherein said cylindrical contact pin makes contact with said contact surface.