Leaf spring, camera module drive mechanism, electronic terminal, and method for producing leaf spring
There is provided a leaf spring which can prevent a reduction in the spring strength and can also prevent a reduction in the electrical conductivity when the thickness of the leaf spring is decreased. The leaf spring includes an outer frame portion an inner frame portion 5 b, 11 b disposed inside the outer frame portion 5 a, 11 a , and spring portions provided between the inner frame portion and the outer frame portion The leaf spring is made of a Cu-based alloy, and has an electrical conductivity of not less than 8% IACS and a 0.2% proof stress of not less than 900 MPa.
1. A leaf spring for use in a camera module drive mechanism, comprising:
an outer frame portion;
an inner frame portion disposed inside the outer frame portion; and
a spring portion connected between the inner frame portion and the outer frame portion, wherein the spring portion has a cross-sectional shape in a cross section perpendicular to an extending direction of the spring portion, wherein the cross-sectional shape has an upper side facing upwardly and a lower side facing downwardly which are of the same length and parallel to each other, and the other two sides being curved inward.
2. The leaf spring according to claim 1 , wherein the leaf spring is produced by using a copper alloy leaf-spring material, and the leaf-spring material has a stress at 0.2% strain of not less than 1150 MPa and a stress at 0.025% strain of not less than 1000 MPa.
3. A camera module drive mechanism comprising:
a chassis;
a lens unit that constitutes an optical system;
a holder disposed in the chassis and housing the lens unit and which is movable in the direction of the optical axis of the lens unit;
a coil provided on the holder;
a yoke and a magnet piece, which are provided on the chassis and which provide a magnetic field to the coil; and
the leaf spring according to claim 1 interposed between the chassis and the holder.
4. A leaf spring for use in a camera module drive mechanism, comprising:
an outer frame portion;
an inner frame portion disposed inside the outer frame portion; and
a spring portion connected between the inner frame portion and the outer frame portion, wherein the spring portion has a cross-sectional shape in a cross section perpendicular to an extending direction of the spring portion, wherein the cross-sectional shape has an upper side facing upwardly and a lower side facing downwardly which are of different lengths and parallel to each other, and the other two sides being curved inward.
5. A camera module drive mechanism comprising:
a chassis;
a lens unit that constitutes an optical system;
a holder disposed in the chassis and housing the lens unit and which is movable in the direction of the optical axis of the lens unit;
a coil provided on the holder;
a yoke and a magnet piece, which are provided on the chassis and which provide a magnetic field to the coil; and
the leaf spring according to claim 4 interposed between the chassis and the holder.
6. The leaf spring according to claim 4 , wherein the leaf spring is produced by using a copper alloy leaf-spring material, and the leaf-spring material has a stress at 0.2% strain of not less than 1150 MPa and a stress at 0.025% strain of not less than 1000 MPa.
7. A leaf spring for use in a camera module drive mechanism and which is produced by using a copper alloy leaf-spring material, comprising:
an outer frame portion;
an inner frame portion disposed inside the outer frame portion; and
a spring portion connected between the inner frame portion and the outer frame portion, wherein the spring portion has a cross-sectional shape in a cross section perpendicular to an extending direction of the spring portion, wherein the cross-sectional shape has an upper side facing upwardly and a lower side facing downwardly which are of the same length or different lengths and parallel to each other, and the other two sides being curved inward, and
wherein the leaf-spring material has an electrical conductivity of not less than 8% IACS and a 0.2% proof stress of not less than 900 MPa.
8. The leaf spring according to claim 7 , wherein the leaf-spring material has a Vickers hardness of not less than 290 HV.
9. The leaf spring according to claim 7 , wherein the leaf-spring material does not contain beryllium as a component thereof.
10. The leaf spring according to claim 7 , wherein the upper side and the lower side are of the same length.
11. The leaf spring according to claim 7 , wherein the upper side and the lower side are of different lengths.
12. A camera module drive mechanism comprising:
a chassis;
a lens unit that constitutes an optical system;
a holder disposed in the chassis and housing the lens unit and which is movable in the direction of the optical axis of the lens unit;
a coil provided on the holder;
a yoke and a magnet piece, which are provided on the chassis and which provide a magnetic field to the coil; and
the leaf spring according to claim 7 interposed between the chassis and the holder.
13. The camera module drive mechanism according to claim 12 , wherein the leaf-spring material has a Vickers hardness of not less than 290 HV.
14. The camera module drive mechanism according to claim 12 , wherein the leaf-spring material does not contain beryllium as a component thereof.
15. The camera module drive mechanism according to claim 12 , wherein the upper side and the lower side are of the same length.
16. The camera module drive mechanism according to claim 12 , wherein the upper side and the lower side are of different lengths.
17. The leaf spring according to claim 7 , wherein the leaf-spring material comprises titanium-copper.