Camera device and drive mechanism
A drive mechanism ( 1 ) of a camera apparatus includes a worm gear ( 4 ) to which a rotational driving force of a drive motor ( 2 ) is transmitted, a worm wheel ( 6 ) around which a helical gear ( 5 ) is formed to engage with the worm gear ( 4 ), and a support frame ( 7 ) which supports the worm wheel ( 6 ) rotatably and movably along a rotation axis. A rotational driving force of the worm gear ( 4 ) is transmitted to the worm wheel ( 6 ) with reduced gear ratio. An externally threaded portion ( 10 ) of a shaft portion ( 8 ) of the worm wheel ( 6 ) is engaged with an internally threaded portion in a supporting hole ( 14 ) of the support frame ( 7 ), so that the shaft portion ( 8 ) moves along the rotation axis when the worm wheel ( 6 ) rotates. Consequently, the rotational driving force transmitted to the worm wheel ( 6 ) is converted into a linear thrust force along the rotation axis. This makes it possible to provide a camera apparatus which can develop a larger thrust force and adjust an amount of travel more finely.
1. A camera apparatus comprising a drive mechanism which converts a rotational driving force of a drive source into a linear thrust force, wherein the camera apparatus comprises:
an image pick up element provided on an ABF frame of the camera apparatus;
a drive gear to which the rotational driving force of the drive source is transmitted;
a driven member around which a helical gear is formed to engage with the drive gear and to which a rotational driving force of the drive gear is transmitted with reduced gear ratio;
a support unit which supports the driven member rotatably around a rotation axis of the driven member and movably along the rotation axis; and
a conversion unit which converts the rotational driving force transmitted to the driven member into a linear thrust force along the rotation axis so that the driven member moves along the rotation axis as the driven member rotates,
wherein the conversion unit comprises:
a first threaded portion which is provided with the driven member; and
a second threaded portion which is provided with the support unit and is engaged with the first threaded portion,
wherein the first threaded portion is provided on one end of the driven member and a shaft member is provided on the other end of the driven member, wherein the shaft member is abutted to the ABF frame, and
the ABF frame tilts as the driven member moves along the rotation axis.
2. The camera apparatus according to claim 1 , wherein a thread direction of the first threaded portion with respect to the second threaded portion is set such that a direction of an auxiliary thrust force along the rotation axis matches a direction of the linear thrust force along the rotation axis, the auxiliary thrust force being received by the driven member from the drive gear via the helical gear when the rotational driving force is transmitted to the driven member from the drive gear, and the linear thrust force resulting from the conversion performed by the conversion unit when the driven member rotates.
3. The camera apparatus according to claim 1 , wherein the helical gear of the driven member has a gear width corresponding to an amount of travel of the driven member along the rotation axis, and a shaft portion which is a supported unit of the driven member has a shaft length corresponding to the amount of travel of the driven member along the rotation axis.
4. The camera apparatus according to claim 1 , wherein the shaft member pushes the ABF frame away from the support unit by the linear thrust force along the rotation axis, and the image pickup element moves forward.
5. The camera apparatus according to claim 1 , further comprises a spring member attached between the support unit and the ABF frame.
6. The camera apparatus according to claim 5 , wherein the spring member pulls the ABF frame toward the support unit by a restoring force, and the image pickup element moves backward.
7. The camera apparatus according to claim 6 , wherein the drive source rotates the drive gear only to one direction to push the ABF frame away from the support unit.
8. The camera apparatus according to claim 7 , wherein the restoring force of the spring member is smaller than the linear thrust force.
9. A drive mechanism which is mounted on a camera apparatus and converts a rotational driving force of a drive source into a linear thrust force, wherein the drive mechanism comprises:
a drive gear to which the rotational driving force of the drive source is transmitted;
a driven member around which a helical gear is formed to engage with the drive gear and to which a rotational driving force of the drive gear is transmitted with reduced gear ratio;
a support unit which supports the driven member rotatably around a rotation axis of the driven member and movably along the rotation axis;
a conversion unit which converts the rotational driving force transmitted to the driven member into a linear thrust force along the rotation axis so that the driven member moves along the rotation axis as the driven member rotates; and
a spring member attached between the support unit and an object to be moved,
wherein the conversion unit comprises:
a first threaded portion which is provided with the driven member; and
a second threaded portion which is provided with the support unit and is engaged with the first threaded portion.
10. The drive mechanism according to claim 9 , wherein the spring member pulls the object to be moved toward the support unit by a restoring force.
11. The drive mechanism according to claim 10 , wherein the drive source rotates the drive gear only to one direction to push the object to be moved away from the support unit.
12. The drive mechanism according to claim 10 , wherein the restoring force of the spring member is smaller than the linear thrust force.
13. The drive mechanism according to claim 9 , wherein the support unit is substantially U-shaped monolithic member comprising two vertical plates and one horizontal plate provided between the two vertical plates, and the second threaded portion is directly engraved in one of the two vertical plates.
14. The drive mechanism according to claim 9 , wherein the first threaded portion is provided on one end of the driven member and a shaft member is provided on the other end of the driven member, the shaft member is abutted to the object to be moved.
15. The drive mechanism according to claim 14 , wherein the shaft member pushes the object to be moved away from the support unit by the linear thrust force along the rotation axis.